Science.gov

Sample records for air current speed

  1. Effects of air current speed on gas exchange in plant leaves and plant canopies

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Tsuruyama, J.; Shibuya, T.; Yoshida, M.; Kiyota, M.

    To obtain basic data on adequate air circulation to enhance plant growth in a closed plant culture system in a controlled ecological life support system (CELSS), an investigation was made of the effects of the air current speed ranging from 0.01 to 1.0 m s-1 on photosynthesis and transpiration in sweetpotato leaves and photosynthesis in tomato seedlings canopies. The gas exchange rates in leaves and canopies were determined by using a chamber method with an infrared gas analyzer. The net photosynthetic rate and the transpiration rate increased significantly as the air current speeds increased from 0.01 to 0.2 m s-1. The transpiration rate increased gradually at air current speeds ranging from 0.2 to 1.0 m s-1 while the net photosynthetic rate was almost constant at air current speeds ranging from 0.5 to 1.0 m s-1. The increase in the net photosynthetic and transpiration rates were strongly dependent on decreased boundary-layer resistances against gas diffusion. The net photosynthetic rate of the plant canopy was doubled by an increased air current speed from 0.1 to 1.0 m s-1 above the plant canopy. The results demonstrate the importance of air movement around plants for enhancing the gas exchange in the leaf, especially in plant canopies in the CELSS.

  2. Effects of saline-water flow rate and air speed on leakage current in RTV coatings

    SciTech Connect

    Kim, S.H.; Hackam, R.

    1995-10-01

    Room temperature vulcanizing (RTV) silicone rubber is increasingly being used to coat porcelain and glass insulators in order to improve their electrical performance in the presence of pollution and moisture. A study of the dependence of leakage current, pulse current count and total charge flowing across the surface of RTV on the flow rate of the saline water and on the compressed air pressure used to create the salt-fog is reported. The fog was directed at the insulating rods either from one or two sides. The RTV was fabricated from polydimethylsiloxane polymer, a filler of alumina trihydrate (ATH), a polymerization catalyst and fumed silica reinforcer, all dispersed in 1,1,1-trichloroethane solvent. The saline water flow rate was varied in the range 0.4 to 2.0 l/min. The compressed air pressure at the input of the fog nozzles was varied from 0.20 to 0.63 MPa. The air speed at the surface of the insulating rods was found to depend linearly on the air pressure measured at the inlet to the nozzles and varied in the range 3 to 14 km/hr. The leakage current increased with increasing flow rate and increasing air speed. This is attributed to the increased loss of hydrophobicity with a larger quantity of saline fog and a larger impact velocities of fog droplets interacting with the surface of the RTV coating.

  3. Alternating-Current Equipment for the Measurement of Fluctuations of Air Speed in Turbulent Flow

    NASA Technical Reports Server (NTRS)

    Mock, W C , Jr

    1937-01-01

    Recent electrical and mechanical improvements have been made in the equipment developed at the National Bureau of Standards for measurement of fluctuations of air speed in turbulent flow. Data useful in the design of similar equipment are presented. The design of rectified alternating-current power supplies for such apparatus is treated briefly, and the effect of the power supplies on the performance of the equipment is discussed.

  4. Effects of air current speed, light intensity and co2 concentration on photosynthesis and transpiration of plant leaves

    NASA Astrophysics Data System (ADS)

    Kitaya, Y.; Tsuruyama, J.; Shibuya, T.; Kiyota, M.

    To obtain basic data for adequate air circulation to promote gas exchange and growth of plants in closed plant culture modules in bioregenerative life support systems in space, the effects of air current speeds less than 0.8 m s-1 on transpiration (Tr) and net photosynthetic rates (Pn) of sweetpotato and barley leaves were determined using a leaf chamber method under different photosynthetic photon flux densities (PPFDs) and CO_2 concentrations. The air current speed inside the leaf chamber was controlled by controlling the input voltages for an air circulation fan. The leaf surface boundary layer resistance was determined by the evaporation rate of wet paper and the water vapor pressure difference between the paper and surrounding air in the leaf chamber. The Tr and Pn of leaves rapidly increased as the air current speed increased from 0.01 to 0.1 m s-1 and gradually increased from 0.1 to 0.8 m s-1. These changes are correspondent to the change of the leaf surface boundary layer resistance. The depression of Tr by low air current speeds was greater than that of Pn. Tr and Pn decreased by 0.5 and 0.7 times, respectively, as the air current speed decreased from 0.8 to 0.01 m s-1. The depressions of Tr and Pn by low air current speeds were most notable at PPFDs of 500 and 250 μmol m-2 s-1, respectively. The air current speeds affected Tr and Pn at a CO_2 concentration of 700 μmol mol-1 as well as at 400 μmol mol-1. The results confirmed the importance of controlling air movement for enhancing Tr and Pn under the relatively high PPFD and elevated CO_2 levels likely in plant culture systems in space.

  5. Influence of current velocity and wind speed on air-water gas exchange in a mangrove estuary

    NASA Astrophysics Data System (ADS)

    Ho, David T.; Coffineau, Nathalie; Hickman, Benjamin; Chow, Nicholas; Koffman, Tobias; Schlosser, Peter

    2016-04-01

    Knowledge of air-water gas transfer velocities and water residence times is necessary to study the fate of mangrove derived carbon exported into surrounding estuaries and ultimately to determine carbon balances in mangrove ecosystems. For the first time, the 3He/SF6 dual tracer technique, which has been proven to be a powerful tool to determine gas transfer velocities in the ocean, is applied to Shark River, an estuary situated in the largest contiguous mangrove forest in North America. The mean gas transfer velocity was 3.3 ± 0.2 cm h-1 during the experiment, with a water residence time of 16.5 ± 2.0 days. We propose a gas exchange parameterization that takes into account the major sources of turbulence in the estuary (i.e., bottom generated shear and wind stress).

  6. Differing current and optical return stroke speeds in lightning

    NASA Astrophysics Data System (ADS)

    Liang, C.; Carlson, B.; Lehtinen, N.; Cohen, M.; Marshall, R. A.; Inan, U.

    2014-04-01

    During the return stroke in downward negative cloud-to-ground lightning, a current wave propagates upward from the ground along the lightning channel. The current wave causes rapid heating of the channel and induces intense optical radiation. The optical radiation wave propagation speed along the channel has been measured to be between 1/5 and 2/3 of the speed of light. The current wave speed is commonly assumed to be the same but cannot be directly measured. Past modeling efforts treat either the thermodynamics or electrodynamics. We present the first model that simultaneously treats the coupled current and thermodynamic physics in the return stroke channel. We utilize numerical simulations using realistic high-temperature air plasma properties that self-consistently solve Maxwell's equations coupled with equations of air plasma thermodynamics. The predicted optical radiation wave speed, rise time, and attenuation agree well with observations. The model predicts significantly higher current return stroke speed.

  7. Development of Air Speed Nozzles

    NASA Technical Reports Server (NTRS)

    Zahm, A F

    1920-01-01

    Report describes the development of a suitable speed nozzle for the first few thousand airplanes made by the United States during the recent war in Europe, and to furnish a basis for more mature instruments in the future. Requirements for the project were to provide a suitable pressure collector for aircraft speed meters and to develop a speed nozzle which would be waterproof, powerful, unaffected by slight pitch and yaw, rugged and easy to manufacture, and uniform in structure and reading, so as not to require individual calibration.

  8. The Altitude Effect on Air Speed Indicators

    NASA Technical Reports Server (NTRS)

    Hersey, M D; Hunt, F L; Eaton, H N

    1921-01-01

    The object of this report is to present the results of a theoretical and experimental study of the effect, on the performance of air speed indicators, of the different atmospheric conditions experienced at various altitudes.

  9. Speed control with end cushion for high speed air cylinder

    DOEpatents

    Stevens, Wayne W.; Solbrig, Charles W.

    1991-01-01

    A high speed air cylinder in which the longitudinal movement of the piston within the air cylinder tube is controlled by pressurizing the air cylinder tube on the accelerating side of the piston and releasing pressure at a controlled rate on the decelerating side of the piston. The invention also includes a method for determining the pressure required on both the accelerating and decelerating sides of the piston to move the piston with a given load through a predetermined distance at the desired velocity, bringing the piston to rest safely without piston bounce at the end of its complete stroke.

  10. 26. "AIR INSTALLATIONS; EDWARDS AIR FORCE BASE, CALIFORNIA; HIGH SPEED ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. "AIR INSTALLATIONS; EDWARDS AIR FORCE BASE, CALIFORNIA; HIGH SPEED TEST TRACK." Drawing No. 10-259. One inch to 400 feet plan of original 10,000-foot sled track. No date. No D.O. series number. No headings as above. - Edwards Air Force Base, South Base Sled Track, Edwards Air Force Base, North of Avenue B, between 100th & 140th Streets East, Lancaster, Los Angeles County, CA

  11. Ozone - Current Air Quality Index

    MedlinePlus

    ... reducing exposure to extremely high levels of particle pollution is available here . Fires: Current Conditions Click to ... Air Quality Basics Air Quality Index | Ozone | Particle Pollution | Smoke from fires | What You Can Do Health ...

  12. Variable current speed controller for eddy current motors

    DOEpatents

    Gerth, H.L.; Bailey, J.M.; Casstevens, J.M.; Dixon, J.H.; Griffith, B.O.; Igou, R.E.

    1982-03-12

    A speed control system for eddy current motors is provided in which the current to the motor from a constant frequency power source is varied by comparing the actual motor speed signal with a setpoint speed signal to control the motor speed according to the selected setpoint speed. A three-phase variable voltage autotransformer is provided for controlling the voltage from a three-phase power supply. A corresponding plurality of current control resistors is provided in series with each phase of the autotransformer output connected to inputs of a three-phase motor. Each resistor is connected in parallel with a set of normally closed contacts of plurality of relays which are operated by control logic. A logic circuit compares the selected speed with the actual motor speed obtained from a digital tachometer monitoring the motor spindle speed and operated the relays to add or substract resistance equally in each phase of the motor input to vary the motor current to control the motor at the selected speed.

  13. 14 CFR 25.1517 - Rough air speed, VRA.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Rough air speed, VRA. 25.1517 Section 25... Limitations § 25.1517 Rough air speed, VRA. A rough air speed, VRA, for use as the recommended turbulence... specified in § 25.335(d); and (3) Is sufficiently less than VMO to ensure that likely speed variation...

  14. 14 CFR 25.1517 - Rough air speed, VRA.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Rough air speed, VRA. 25.1517 Section 25... Limitations § 25.1517 Rough air speed, VRA. A rough air speed, VRA, for use as the recommended turbulence... specified in § 25.335(d); and (3) Is sufficiently less than VMO to ensure that likely speed variation...

  15. 14 CFR 25.1517 - Rough air speed, VRA.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Rough air speed, VRA. 25.1517 Section 25... Limitations § 25.1517 Rough air speed, VRA. A rough air speed, VRA, for use as the recommended turbulence... specified in § 25.335(d); and (3) Is sufficiently less than VMO to ensure that likely speed variation...

  16. 14 CFR 25.1517 - Rough air speed, VRA.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Rough air speed, VRA. 25.1517 Section 25... Limitations § 25.1517 Rough air speed, VRA. A rough air speed, VRA, for use as the recommended turbulence... specified in § 25.335(d); and (3) Is sufficiently less than VMO to ensure that likely speed variation...

  17. 14 CFR 25.1517 - Rough air speed, VRA.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Rough air speed, VRA. 25.1517 Section 25... Limitations § 25.1517 Rough air speed, VRA. A rough air speed, VRA, for use as the recommended turbulence... specified in § 25.335(d); and (3) Is sufficiently less than VMO to ensure that likely speed variation...

  18. Ring current development during high speed streams

    NASA Astrophysics Data System (ADS)

    Jordanova, V. K.; Matsui, H.; Puhl-Quinn, P. A.; Thomsen, M. F.; Mursula, K.; Holappa, L.

    2009-07-01

    Episodes of southward (Bz<0) interplanetary magnetic field (IMF) which lead to disturbed geomagnetic conditions are associated either with coronal mass ejections (CMEs) and possess long and continuous negative IMF Bz excursions, or with high speed solar wind streams (HSS) whose geoeffectiveness is due to IMF Bz profiles fluctuating about zero with various amplitudes and duration. We simulate ring current evolution during a HSS-driven storm that occurred during 24-26 October 2002 and compare its dynamics with a CME-driven storm of similar strength during 22-23 April 2001. We use our kinetic ring current-atmosphere interactions model (RAM), and investigate the mechanisms responsible for trapping particles and for causing their loss. Ring current evolution depends on the interplay of time-dependent inflow of plasma from the magnetotail, particle acceleration and loss (mainly due to charge exchange) along adiabatic drift paths, and outflow of plasma from the dayside magnetopause; all of these processes are incorporated in our model. We compare results from simulations using a newly developed, Cluster data based, University of New Hampshire inner magnetospheric electric field (UNH-IMEF) convection model with simulations using a Volland-Stern (V-S) type convection model. We find that, first, periods of increased magnetospheric convection coinciding with enhancements of plasma sheet density are needed for strong ring current buildup. Second, during the HSS-driven storm the convection potential from UNH-IMEF model is highly variable and causes sporadic shallow injections resulting in a weak ring current. The long period of enhanced convection during the CME-driven storm causes a continuous ion injection penetrating to lower L shells and stronger ring current buildup. V-S model predicts larger ring current injection during both storms. Third, the RAM driven by either convection model underestimates the total ring current energy during the recovery phase of the HSS storm

  19. NACA Flight-Path Angle and Air-Speed Recorder

    NASA Technical Reports Server (NTRS)

    Coleman, Donald G

    1926-01-01

    A new trailing bomb-type instrument for photographically recording the flight-path angle and air speed of aircraft in unaccelerated flight is described. The instrument consists essentially of an inclinometer, air-speed meter and a film-drum case. The inclinometer carries an oil-damped pendulum which records optically the flight-path angle upon a rotating motor-driven film drum. The air-speed meter consists of a taut metal diaphragm of high natural frequency which is acted upon by the pressure difference of a Prandtl type Pitot-static tube. The inclinometer record and air-speed record are made optically on the same sensitive film. Two records taken by this instrument are shown.

  20. Pressure of air on coming to rest from various speeds

    NASA Technical Reports Server (NTRS)

    Zahm, A F

    1927-01-01

    The text gives theoretical formulas from which is computed a table for the pressure of air on coming to rest from various speeds, such as those of aircraft and propeller blades. Pressure graphs are given for speeds from 1 cm. Sec. up to those of swift projectiles.

  1. N.A.C.A. Recording Air Speed Meter

    NASA Technical Reports Server (NTRS)

    Norton, F H

    1921-01-01

    A new type of air speed meter is described which was designed by the technical staff of the National Advisory Committee for Aeronautics. The instrument consists essentially of a tight metal diaphragm of high natural period which is acted upon by the pressure difference of a pitot-static head. The resulting deflection of this diaphragm is recorded optically on a moving film.

  2. The Altitude Effect on Air Speed Indicators II

    NASA Technical Reports Server (NTRS)

    Eaton, H N; Macnair, W A

    1923-01-01

    In an investigation described in NACA Technical Report 110, it was shown that under certain conditions, particularly for the relatively low-speed flight of airships, the data obtained were not sufficiently accurate. This report describes an investigation in which the data obtained were sufficiently accurate and complete to enable the viscosity correction to be deduced quantitatively for a number of the air-speed pressure nozzles in common use. The report opens with a discussion of the theory of the performance of air-speed nozzles and of the calibration of the indicators, from which the theory of the altitude correction is developed. Then follows the determination of the performance characteristics of the nozzles and calibration constants used for the indicators. In the latter half of the report, the viscosity correction is computed for the Zahm Pitot-venturi nozzles.

  3. The influence of air friction in speed skating.

    PubMed

    van Ingen Schenau, G J

    1982-01-01

    With the use of a wind tunnel the air friction force Fw on six speed skaters of different body builds was measured. The dependence of the drag coefficient CD on air velocity v and the influence of different skating postures on drag were investigated. At an air velocity of v = 12 m/sec, an angle between upper and lower leg of 110 degrees and a horizontal trunk position, the measured air friction constant kn(=Fw/V2) of all subjects was calculated from their height l and weight m according to the formula 0.0205 l3 square root m (standard error 2%). CD and as a consequence k appeared to be strongly dependent on air velocity. Expressions to correct k for other velocities and postures were derived and substituted into a power balance by which the influence of posture, ice condition, wind and altitude on performance was predicted.

  4. Adjustments of wingbeat frequency and air speed to air density in free-flying migratory birds.

    PubMed

    Schmaljohann, H; Liechti, F

    2009-11-01

    Birds adjust their flight behaviour to the physical properties of the air. Lift and drag, the two major properties in aerodynamics, are highly dependent on air density. With decreasing air density drag is reduced and lift per wingbeat decreases. According to flight mechanical theory, wingbeat frequency and air speed should increase with decreasing air density, i.e. increasing flight altitude. Although wind tunnel experiments have shed light on many aspects of avian flight, the effect of air density remained ambiguous, because air density could not be adjusted in wind tunnels, until now. By means of radar we recorded tracks of several thousand free-flying individual birds during nocturnal migration. From these tracks we derived wingbeat frequencies and air speeds covering air densities from 0.84 kg m(-3) to 1.13 kg m(-3), corresponding to an altitudinal range of about 3000 m. We demonstrate here with this sample of nocturnal migrants that: (1) wingbeat frequency decreases with air density (which corresponds to an increase in flap-gliding flyers by 0.4 Hz km(-1) and in bounding flyers by 1.1 Hz km(-1)), (2) reducing wingbeat frequency to equivalent sea level values did not abolish the dependency on air density, as expected by flight mechanical theory, and (3) bounding flyers show a higher response in their flight behavioural adjustments to changes in air density than flap-gliding flyers. With respect to air speed flap-gliding flyers increase their air speed by 1.0 m s(-1) km(-1) and bounding flyers by 1.4 m s(-1) km(-1).

  5. Current Densities in speed analyzer with different symmetries

    SciTech Connect

    Valdeblanquez, E.

    2006-12-04

    A comparative analysis of the currents in speed analyzer of speeds is made with different symmetries. Three kinds of symmetries are considered; plane, cylindrical and spherical. The analyzers considered are formed by threes electrodes, the selector grid, the discriminator and the collector. The selector grid has a negative potential and for the coulombian effect the space charge is formed with the ionic thermal bath. Using kinetic theory a strongly non linear differential equation is obtained which is solved by numerical calculation.

  6. Open tube guideway for high speed air cushioned vehicles

    NASA Technical Reports Server (NTRS)

    Goering, R. S. (Inventor)

    1974-01-01

    This invention is a tubular shaped guideway for high-speed air-cushioned supported vehicles. The tubular guideway is split and separated such that the sides of the guideway are open. The upper portion of the tubular guideway is supported above the lower portion by truss-like structural members. The lower portion of the tubular guideway may be supported by the terrain over which the vehicle travels, on pedestals or some similar structure.

  7. The mass and speed dependence of meteor air plasma temperatures.

    PubMed

    Jenniskens, Peter; Laux, Christophe O; Wilson, Michael A; Schaller, Emily L

    2004-01-01

    The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

  8. The mass and speed dependence of meteor air plasma temperatures

    NASA Technical Reports Server (NTRS)

    Jenniskens, Peter; Laux, Christophe O.; Wilson, Michael A.; Schaller, Emily L.

    2004-01-01

    The speed and mass dependence of meteor air plasma temperatures is perhaps the most important data needed to understand how small meteoroids chemically change the ambient atmosphere in their path and enrich the ablated meteoric organic matter with oxygen. Such chemistry can play an important role in creating prebiotic compounds. The excitation conditions in various air plasma emissions were measured from high-resolution optical spectra of Leonid storm meteors during NASA's Leonid Multi-Instrument Aircraft Campaign. This was the first time a sufficient number and range of temperature measurements were obtained to search for meteoroid mass and speed dependencies. We found slight increases in temperature with decreasing altitude, but otherwise nearly constant values for meteoroids with speeds between 35 and 72 km/s and masses between 10(-5) g and 1 g. We conclude that faster and more massive meteoroids produce a larger emission volume, but not a higher air plasma temperature. We speculate that the meteoric plasma may be in multiphase equilibrium with the ambient atmosphere, which could mean lower plasma temperatures in a CO(2)-rich early Earth atmosphere.

  9. Effect of Initial Mixture Temperature on Flame Speed of Methane-Air, Propane-Air, and Ethylene-Air Mixtures

    NASA Technical Reports Server (NTRS)

    Dugger, Gordon L

    1952-01-01

    Flame speeds based on the outer edge of the shadow cast by the laminar Bunsen cone were determined as functions of composition for methane-air mixtures at initial mixture temperatures ranging from -132 degrees to 342 degrees c and for propane-air and ethylene-air mixtures at initial mixture temperatures ranging from -73 degrees to 344 degrees c. The data showed that maximum flame speed increased with temperature at an increasing rate. The percentage change in flame speed with change in initial temperature for the three fuels followed the decreasing order, methane, propane, and ethylene. Empirical equations were determined for maximum flame speed as a function of initial temperature over the temperature range covered for each fuel. The observed effect of temperature on flame speed for each of the fuels was reasonably well predicted by either the thermal theory as presented by Semenov or the square-root law of Tanford and Pease.

  10. An air bearing system for small high speed gas turbines

    NASA Astrophysics Data System (ADS)

    Turner, A. B.; Davies, S. J.; Nimir, Y. L.

    1994-03-01

    This paper describes the second phase of an experimental program concerning the application of air bearings to small turbomachinery test rigs and small gas turbines. The first phase examined externally pressurized (EP) journal bearings, with a novel EP thrust bearing, for application to 'warm air' test rigs, and was entirely successful at rotational speeds in excess of 100,000 rpm. This second phase examined several designs of tilting pad-spiring journal bearings, one with a novel form of externally pressurized pad, but all using the original EP thrust bearing. The designs tested are described, including some oscillogram traces, for tests up to a maximum of 70,000 rpm; the most successful using a carbon pad-titanium beam spring arrangement. The thrust bearing which gave trouble-free operation throughout, is also described. The results of an original experiment to measure the 'runway speed' of a radial inflow turbine are also presented, which show that overspeeds of 58 percent above the design speed can result from free-power turbine coupling failure.

  11. Low pressure high speed Stirling air engine. Final technical report

    SciTech Connect

    Ross, M.A.

    1980-06-16

    The purpose of this project was to design, construct and test a simple, appropriate technology low pressure, high speed, wood-fired Stirling air engine of 100 W output. The final design was a concentric piston/displacer engine of 454 in. bore and 1 in. stroke with a rhombic drive mechanism. The project engine was ultimately completed and tested, using a propane burner for all tests as a matter of convenience. The 100 W aim was exceeded, at atmospheric pressure, over a wide range of engine speed with the maximum power being 112 W at 1150 rpm. A pressure can was constructed to permit pressurization; however the grant funds were running out, and the only pressurized power test attempted was unsuccessful due to seal difficulties. This was a disappointment because numerous tests on the 4 cubic inch engine suggested power would be more than doubled with pressurization at 25 psig. A manifold was designed and constructed to permit operation of the engine over a standard No. 40 pot bellied stove. The engine was run successfully, but at reduced speed and power, over this stove. The project engine started out being rather noisy in operation, but modifications ultimately resulted in a very quiet engine. Various other difficulties and their solutions also are discussed. (LCL)

  12. Quantification and control of the spatiotemporal gradients of air speed and air temperature in an incubator.

    PubMed

    Van Brecht, A; Aerts, J M; Degraeve, P; Berckmans, D

    2003-11-01

    Around the optimal incubator air temperature only small spatiotemporal deviations are allowed. However, air speed and air temperature are not uniformly distributed in the total volume of the incubator due to obstruction of the eggs and egg trays. The objectives of this research were (1) to quantify the spatiotemporal gradients in temperature and velocity and (2) to develop and validate a control algorithm to increase the uniformity in temperature during the entire incubation process. To improve the uniformity of air temperature, the airflow pattern and the air quality need to be controlled more optimally. These data show that the air temperature between the eggs at a certain position in a large incubator is the result of (1) the mean air temperature of the incubator; (2) the exchange of heat between the egg and its micro-environment, which is affected by the air speed at that certain position; (3) the time-variable heat production of the embryo; and (4) the heat influx or efflux as a result from the movement of hot or cold air in the incubator toward that position, which is affected by the airflow pattern. This implies that the airflow pattern needs to be controlled in a more optimal way. To maximize the uniformity of air temperature, an active and adaptive control of the three-dimensional (3-D) airflow pattern has been developed and tested. It was found to improve the spatiotemporal temperature distribution. The chance of having a temperature reading in the interval from 37.5 to 38.1 degrees C increased by 3% compared to normal operating conditions.

  13. High-Speed Civil Transport Will Revolutionize Air Travel

    NASA Technical Reports Server (NTRS)

    1998-01-01

    NASA is developing advanced technologies that will allow industry to build a high-speed civil transport that will revolutionize overseas air travel. The technology challenges include developing low-cost materials and structural concepts as well as supersonic engines that can meet stringent noise and emissions standards. NASA's goal is to provide enabling technologies that will reduce the travel time to the Far East by 50 percent within 25 years, and do so at today's subsonic ticket prices. This research is part of NASA's Aeronautics and Space Transportation Technology (ASTT) Enterprise's strategy to sustain U.S. leadership in aeronautics and space. The Enterprise has set bold goals that are grouped into Three Pillars: Global Civil Aviation, Revolutionary Technology Leaps and Access to Space.

  14. Precision electronic speed controller for an alternating-current motor

    DOEpatents

    Bolie, V.W.

    A high precision controller for an alternating-current multi-phase electrical motor that is subject to a large inertial load. The controller was developed for controlling, in a neutron chopper system, a heavy spinning rotor that must be rotated in phase-locked synchronism with a reference pulse train that is representative of an ac power supply signal having a meandering line frequency. The controller includes a shaft revolution sensor which provides a feedback pulse train representative of the actual speed of the motor. An internal digital timing signal generator provides a reference signal which is compared with the feedback signal in a computing unit to provide a motor control signal. The motor control signal is a weighted linear sum of a speed error voltage, a phase error voltage, and a drift error voltage, each of which is computed anew with each revolution of the motor shaft. The speed error signal is generated by a novel vernier-logic circuit which is drift-free and highly sensitive to small speed changes. The phase error is also computed by digital logic, with adjustable sensitivity around a 0 mid-scale value. The drift error signal, generated by long-term counting of the phase error, is used to compensate for any slow changes in the average friction drag on the motor. An auxillary drift-byte status sensor prevents any disruptive overflow or underflow of the drift-error counter. An adjustable clocked-delay unit is inserted between the controller and the source of the reference pulse train to permit phase alignment of the rotor to any desired offset angle. The stator windings of the motor are driven by two amplifiers which are provided with input signals having the proper quadrature relationship by an exciter unit consisting of a voltage controlled oscillator, a binary counter, a pair of read-only memories, and a pair of digital-to-analog converters.

  15. 6. FAN HOUSE OF 8FOOT HIGH SPEED TUNNEL. AIR INTAKES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. FAN HOUSE OF 8-FOOT HIGH SPEED TUNNEL. AIR INTAKES AND FILTERS ARE ENCLOSED IN THE UPPER LEVEL STRUCTURE. - NASA Langley Research Center, 8-Foot High Speed Wind Tunnel, 641 Thornell Avenue, Hampton, Hampton, VA

  16. The development of the dental high-speed air turbine handpiece. Part 1.

    PubMed

    Dyson, J E; Darvell, B W

    1993-02-01

    The high-speed air turbine handpiece is currently used for most dental cutting procedures and has been in widespread use for more than thirty years. Although reports of its historical background have been previously published these have not dealt with all relevant developments and some inconsistencies exist. The history of the development of turbines and their application in dental cutting systems from the late 19th century to the present day is now reviewed. An historical account of the recognition of benefits that may accrue from rotary cutting at increased speeds is given and the various attempts that have been made to design equipment capable of high speeds are discussed. Consideration is given to the development of non-rotary cutting devices, as is the failure of these adequately to replace the air turbine handpiece for routine work. It is concluded that the air turbine handpiece will continue to hold a leading position in the field for some years to come but that future improvements would be facilitated by the development of an understanding of the theoretical aspects of its behaviour. PMID:8447772

  17. Transduction in Drosophila olfactory receptor neurons is invariant to air speed

    PubMed Central

    Zhou, Yi

    2012-01-01

    In the vertebrate nose, increasing air speed tends to increase the magnitude of odor-evoked activity in olfactory receptor neurons (ORNs), given constant odor concentration and duration. It is often assumed that the same is true of insect olfactory organs, but this has not been directly tested. In this study, we examined the effect of air speed on ORN responses in Drosophila melanogaster. We constructed an odor delivery device that allowed us to independently vary concentration and air speed, and we used a fast photoionization detector to precisely measure the actual odor concentration at the antenna while simultaneously recording spikes from ORNs in vivo. Our results demonstrate that Drosophila ORN odor responses are invariant to air speed, as long as odor concentration is kept constant. This finding was true across a >100-fold range of air speeds. Because odor hydrophobicity has been proposed to affect the air speed dependence of olfactory transduction, we tested a >1,000-fold range of hydrophobicity values and found that ORN responses are invariant to air speed across this full range. These results have implications for the mechanisms of odor delivery to Drosophila ORNs. Our findings are also significant because flies have a limited ability to control air flow across their antennae, unlike terrestrial vertebrates, which can control air flow within their nasal cavity. Thus, for the fly, invariance to air speed may be adaptive because it confers robustness to changing wind conditions. PMID:22815404

  18. Precision electronic speed controller for an alternating-current

    DOEpatents

    Bolie, Victor W.

    1988-01-01

    A high precision controller for an alternating-current multi-phase electrical motor that is subject to a large inertial load. The controller was developed for and is particularly suitable for controlling, in a neutron chopper system, a heavy spinning rotor that must be rotated in phase-locked synchronism with a reference pulse train that is representative of an ac power supply signal having a meandering line frequency. The controller includes a shaft revolution sensor which provides a feedback pulse train representative of the actual speed of the motor. An internal digital timing signal generator provides a reference signal which is compared with the feedback signal in a computing unit to provide a motor control signal. In the preferred embodiment, the motor control signal is a weighted linear sum of a speed error voltage, a phase error voltage, and a drift error voltage, each of which is computed anew with each revolution of the motor shaft. The stator windings of the motor are driven by two amplifiers which are provided with input signals having the proper quadrature relationship by an exciter unit consisting of a voltage controlled oscillator, a binary counter, a pair of readonly memories, and a pair of digital-to-analog converters.

  19. Comparison of rotational speeds and torque properties between air-bearing and ball-bearing air-turbine handpieces.

    PubMed

    Taira, M; Wakasa, K; Yamaki, M; Matsui, A

    1989-06-01

    We examined the effects of air pressure on the free-running speed of air-bearing and torque-type ball-bearing air-turbine handpieces. The air pressure for the former should be kept at a certain high level to maintain the stable super-thin air-bearing film and to provide the quasi-constant speed of around 420,000 to 480,000 rpm. On the other hand, the air pressure for the latter could be adjusted to provide some varieties of speeds, ranging from about 150,000 to 320,000 rpm. Subsequently, to compare torque properties and cutting effectiveness between these two handpieces, weight-load cutting tests were conducted, using a glass-ceramic workpiece and a commercial diamond point. It was confirmed that the air-bearing handpiece had the lower torque power but exhibited better cutting effectiveness, compared with its counterpart.

  20. High-speed low-current-density 850 nm VCSELs

    NASA Astrophysics Data System (ADS)

    Larsson, Anders; Westbergh, Petter; Gustavsson, Johan; Haglund, Åsa

    2010-02-01

    The design of an oxide confined 850 nm VCSEL has been engineered for high speed operation at low current density. Strained InGaAs/AlGaAs QWs, with a careful choice of In and Al concentrations based on rigorous band structure and gain calculations, were used to increase differential gain and reduce threshold carrier density. Various measures, including multiple oxide layers and a binary compound in the lower distributed Bragg reflector, were implemented for reducing capacitance and thermal impedance. Modulation bandwidths > 20 GHz at 25°C and > 15 GHz at 85°C were obtained. At room temperature, the bandwidth was found to be limited primarily by the still relatively large oxide capacitance, while at 85°C the bandwidth was also limited by the thermal saturation of the resonance frequency. Transmission up to 32 Gb/s (on-off keying) over multimode fiber was successfully demonstrated with the VCSEL biased at a current density of only 11 kA/cm2. In addition, using a more spectrally efficient modulation format (16 QAM subcarrier multiplexing), transmission at 40 Gb/s over 200 m multimode fiber was demonstrated.

  1. Arctic sea ice circulation and drift speed: Decadal trends and ocean currents

    NASA Astrophysics Data System (ADS)

    Kwok, R.; Spreen, G.; Pang, S.

    2013-05-01

    We examine the basinwide trends in sea ice circulation and drift speed and highlight the changes between 1982 and 2009 in connection to regional winds, multiyear sea ice coverage, ice export, and the thinning of the ice cover. The polarity of the Arctic Oscillation (AO) is used as a backdrop for summarizing the variance and shifts in decadal drift patterns. The 28-year circulation fields show a net strengthening of the Beaufort Gyre and the Transpolar Drift, especially during the last decade. The imprint of the arctic dipole anomaly on the mean summer circulation is evident (2001-2009) and enhances summer ice area export at the Fram Strait. Between 2001 and 2009, the large spatially averaged trends in drift speeds (winter: +23.6%/decade, summer: +17.7%/decade) are not explained by the much smaller trends in wind speeds (winter: 1.46%/decade, summer: -3.42%/decade). Notably, positive trends in drift speed are found in regions with reduced multiyear sea ice coverage. Over 90% of the Arctic Ocean has positive trends in drift speed and negative trends in multiyear sea ice coverage. The increased responsiveness of ice drift to geostrophic wind is consistent with a thinner and weaker seasonal ice cover and suggests large-scale changes in the air-ice-ocean momentum balance. The retrieved mean ocean current field from decadal-scale average ice motion captures a steady drift from Siberia to the Fram Strait, an inflow north of the Bering Strait, and a westward drift along coastal Alaska. This mean current is comparable to geostrophic currents from satellite-derived dynamic topography.

  2. Air gun wounding and current UK laws controlling air weapons.

    PubMed

    Bruce-Chwatt, Robert Michael

    2010-04-01

    Air weapons whether rifles or pistols are, potentially, lethal weapons. The UK legislation is complex and yet little known to the public. Hunting with air weapons and the laws controlling those animals that are permitted to be shot with air weapons is even more labyrinthine due to the legal power limitations on the possession of air weapons. Still relatively freely available by mail order or on the Internet, an increasing number of deaths have been reported from the misuse of air weapons or accidental discharges. Ammunition for air weapons has become increasingly sophisticated, effective and therefore increasingly dangerous if misused, though freely available being a mere projectile without a concomitant cartridge containing a propellant and an initiator.

  3. HIGH-SPEED GC/MS FOR AIR ANALYSIS

    EPA Science Inventory

    High speed or fast gas chromatography (FGC) consists of narrow bandwidth injection into a high-speed carrier gas stream passing through a short column leading to a fast detector. Many attempts have been made to demonstrate FGC, but until recently no practical method for routin...

  4. Effect of car speed on amount of air supplied by ventilation system to the space of car cabin

    NASA Astrophysics Data System (ADS)

    Fišer, Jan; Pokorný, Jan

    2014-03-01

    The amount of air supplied by ventilation system (HVAC system) of a car into a cabin is one of the main parameters for the correct simulation and prediction of a car cabin heat load. This amount is not based only on the current setting of the HVAC system, but also on the actual operating conditions and speed of the car. The authors therefore carried out experiments in the cabin of a passenger car in real traffic, while observing the amount of air on the speed of the car and setting of flap in mixing chamber. In a subsequent analysis the authors defined dependence of the airflow rate supplied by HVAC system on the speed of the car. Obtained empirical formulas were then used as a part of the code which calculates the data for the HVAC boundary conditions in the simulation of the car cabin environment.

  5. Design criteria for light high speed desert air cushion vehicles

    NASA Astrophysics Data System (ADS)

    Abulnaga, B. E.

    An evaluation is made of the applicability and prospective performance of ACVs in trans-Saharan cargo transport, in view of the unique characteristics of the dry sand environment. The lightweight/high-speed ACV concept envisioned is essentially ground effect aircraftlike, with conventional wheels as a low-speed backup suspension system. A propeller is used in ground effect cruise. Attention is given to the effects on vehicle stability and performance of sandy surface irregularities of the desert topography and of cross-winds from various directions relative to vehicle movement.

  6. An Inexpensive and Versatile Version of Kundt's Tube for Measuring the Speed of Sound in Air

    ERIC Educational Resources Information Center

    Papacosta, Pangratios; Linscheid, Nathan

    2016-01-01

    Experiments that measure the speed of sound in air are common in high schools and colleges. In the Kundt's tube experiment, a horizontal air column is adjusted until a resonance mode is achieved for a specific frequency of sound. When this happens, the cork dust in the tube is disturbed at the displacement antinode regions. The location of the…

  7. An Inexpensive and Versatile Version of Kundt's Tube for Measuring the Speed of Sound in Air

    NASA Astrophysics Data System (ADS)

    Papacosta, Pangratios; Linscheid, Nathan

    2016-01-01

    Experiments that measure the speed of sound in air are common in high schools and colleges. In the Kundt's tube experiment, a horizontal air column is adjusted until a resonance mode is achieved for a specific frequency of sound. When this happens, the cork dust in the tube is disturbed at the displacement antinode regions. The location of the displacement antinodes enables the measurement of the wavelength of the sound that is being used. This paper describes a design that uses a speaker instead of the traditional aluminum rod as the sound source. This allows the use of multiple sound frequencies that yield a much more accurate speed of sound in air.

  8. Sustained diffusive alternating current gliding arc discharge in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Zhu, Jiajian; Gao, Jinlong; Li, Zhongshan; Ehn, Andreas; Aldén, Marcus; Larsson, Anders; Kusano, Yukihiro

    2014-12-01

    Rapid transition from glow discharge to thermal arc has been a common problem in generating stable high-power non-thermal plasmas especially at ambient conditions. A sustained diffusive gliding arc discharge was generated in a large volume in atmospheric pressure air, driven by an alternating current (AC) power source. The plasma column extended beyond the water-cooled stainless steel electrodes and was stabilized by matching the flow speed of the turbulent air jet with the rated output power. Comprehensive investigations were performed using high-speed movies measured over the plasma column, synchronized with simultaneously recorded current and voltage waveforms. Dynamic details of the novel non-equilibrium discharge are revealed, which is characterized by a sinusoidal current waveform with amplitude stabilized at around 200 mA intermediate between thermal arc and glow discharge, shedding light to the governing mechanism of the sustained spark-suppressed AC gliding arc discharge.

  9. Tables for pressure of air on coming to rest from various speeds

    NASA Technical Reports Server (NTRS)

    Zahm, A F; Louden, F A

    1930-01-01

    In Technical Report no. 247 of the National Advisory Committee for Aeronautics theoretical formulas are given from which was computed a table for the pressure of air on coming to rest from various speeds, such as those of aircraft and propeller blades. In that report, the table gave incompressible and adiabatic stop pressures of air for even-speed intervals in miles per hour and for some even-speed intervals in knots per hour. Table II of the present report extends the above-mentioned table by including the stop pressures of air for even-speed intervals in miles per hour, feet per-second, knots per hour, kilometers per hour, and meters per second. The pressure values in table II are also more exact than values given in the previous table. To furnish the aeronautical engineer with ready numerical formulas for finding the pressure of air on coming to rest, table I has been derived for the standard values specified below it. This table first presents the theoretical pressure-speed formulas and their working forms in C. G. S. Units as given in NACA Technical Report No. 247, then furnishes additional working formulas for several special units of speed. (author)

  10. Increased Speed: 3D Silicon Sensors. Fast Current Amplifiers

    SciTech Connect

    Parker, Sherwood; Kok, Angela; Kenney, Christopher; Jarron, Pierre; Hasi, Jasmine; Despeisse, Matthieu; Da Via, Cinzia; Anelli, Giovanni; /CERN

    2012-05-07

    The authors describe techniques to make fast, sub-nanosecond time resolution solid-state detector systems using sensors with 3D electrodes, current amplifiers, constant-fraction comparators or fast wave-form recorders, and some of the next steps to reach still faster results.

  11. A miniaturized piezoelectric turbine with self-regulation for increased air speed range

    SciTech Connect

    Fu, Hailing Yeatman, Eric M.

    2015-12-14

    This paper presents the design and demonstration of a piezoelectric turbine with self-regulation for increased air speed range. The turbine's transduction is achieved by magnetic “plucking” of a piezoelectric beam by the passing rotor. The increased speed range is achieved by the self-regulating mechanism which can dynamically adjust the magnetic coupling between the magnets on the turbine rotor and the piezoelectric beam using a micro-spring. The spring is controlled passively by the centrifugal force of the magnet on the rotor. This mechanism automatically changes the relative position of the magnets at different rotational speeds, making the coupling weak at low airflow speeds and strong at high speeds. Hence, the device can start up with a low airflow speed, and the output power can be ensured when the airflow speed is high. A theoretical model was established to analyse the turbine's performance, advantages, and to optimize its design parameters. A prototype was fabricated and tested in a wind tunnel. The start-up airflow speed was 2.34 m/s, showing a 30% improvement against a harvester without the mechanism.

  12. A miniaturized piezoelectric turbine with self-regulation for increased air speed range

    NASA Astrophysics Data System (ADS)

    Fu, Hailing; Yeatman, Eric M.

    2015-12-01

    This paper presents the design and demonstration of a piezoelectric turbine with self-regulation for increased air speed range. The turbine's transduction is achieved by magnetic "plucking" of a piezoelectric beam by the passing rotor. The increased speed range is achieved by the self-regulating mechanism which can dynamically adjust the magnetic coupling between the magnets on the turbine rotor and the piezoelectric beam using a micro-spring. The spring is controlled passively by the centrifugal force of the magnet on the rotor. This mechanism automatically changes the relative position of the magnets at different rotational speeds, making the coupling weak at low airflow speeds and strong at high speeds. Hence, the device can start up with a low airflow speed, and the output power can be ensured when the airflow speed is high. A theoretical model was established to analyse the turbine's performance, advantages, and to optimize its design parameters. A prototype was fabricated and tested in a wind tunnel. The start-up airflow speed was 2.34 m/s, showing a 30% improvement against a harvester without the mechanism.

  13. An Undergraduate Experiment for the Measurement of the Speed of Sound in Air: Phenomena and Discussion

    ERIC Educational Resources Information Center

    Yang, Hujiang; Zhao, Xiaohong; Wang, Xin; Xiao, Jinghua

    2012-01-01

    In this paper, we present and discuss some phenomena in an undergraduate experiment for the measurement of the speed of sound in air. A square wave distorts when connected to a piezoelectric transducer. Moreover, the amplitude of the receiving signal varies with the driving frequency. Comparing with the Gibbs phenomenon, these phenomena can be…

  14. Dispersal and air entrainment in unconfined dilute pyroclastic density currents

    NASA Astrophysics Data System (ADS)

    Andrews, Benjamin J.

    2014-09-01

    Unconfined scaled laboratory experiments show that 3D structures control the behavior of dilute pyroclastic density currents (PDCs) during and after liftoff. Experiments comprise heated and ambient temperature 20 μm talc powder turbulently suspended in air to form density currents within an unobstructed 8.5 × 6 × 2.6-m chamber. Comparisons of Richardson, thermal Richardson, Froude, Stokes, and settling numbers and buoyant thermal to kinetic energy densities show good agreement between experimental currents and dilute PDCs. The experimental Reynolds numbers are lower than those of PDCs, but the experiments are fully turbulent; thus, the large-scale dynamics are similar between the two systems. High-frequency, simultaneous observation in three orthogonal planes shows that the currents behave very differently than previous 2D (i.e., confined) currents. Specifically, whereas ambient temperature currents show radial dispersal patterns, buoyancy reversal, and liftoff of heated currents focuses dispersal along narrow axes beneath the rising plumes. The aspect ratios, defined as the current length divided by a characteristic width, are typically 2.5-3.5 in heated currents and 1.5-2.5 in ambient temperature currents, reflecting differences in dispersal between the two types of currents. Mechanisms of air entrainment differ greatly between the two currents: entrainment occurs primarily behind the heads and through the upper margins of ambient temperature currents, but heated currents entrain air through their lateral margins. That lateral entrainment is much more efficient than the vertical entrainment, >0.5 compared to ˜0.1, where entrainment is defined as the ratio of cross-stream to streamwise velocity. These experiments suggest that generation of coignimbrite plumes should focus PDCs along narrow transport axes, resulting in elongate rather than radial deposits.

  15. An experimental investigation of the aeroacoustic properties of high-speed, helium/air mixture axisymmetric jets

    NASA Astrophysics Data System (ADS)

    Doty, Michael Justin

    The acoustic and aerodynamic properties of high-speed axisymmetric jets are investigated experimentally in a recently refurbished high-speed jet noise facility. Mach numbers from 0.5 to 1.5 are tested with an emphasis on Mach 0.9 and 1.5 jets. Reynolds numbers for the current study range from approximately 200,000 to 600,000. The properties of heated jets which are important in aeroacoustic studies, namely low density and high velocity, are simulated in the current study by adding helium to the jet flow. In addition, an optical deflectometry system is used to provide unique two-point space-time correlation measurements within the jet shear layer. A combination of acoustic, mean flow, and optical deflectometry measurements are made for both pure air and helium/air mixture jets at various helium concentrations. Far-field acoustic measurements indicate very reasonable agreement between previously measured heated jet directivity patterns and those at simulated temperature ratios using helium/air mixture jets. The addition of helium also shows strong similarities to the addition of heat in the mean velocity profile measurements. A shortening of the potential core and a slight decrease in jet spreading rate are observed with helium addition---the same trends observed for heated jets. Optical deflectometry measurements near the end of the potential core along the jet lip line exhibit distinct cross-correlation curves for the pure air jet cases. However, helium/air mixture jets display much lower levels of correlation and little evidence of large-scale structure in the measured spectra. It is believed the strong visual density gradients throughout the shear layer effectively mask the large-scale structure, thus reflecting a limitation of the optical deflectometer. Finally, a decrease in normalized convection velocity with simulated heating (helium addition) is observed.

  16. Dynamic simulation and safety evaluation of high-speed trains meeting in open air

    NASA Astrophysics Data System (ADS)

    Li, Songyan; Zheng, Zhijun; Yu, Jilin; Qian, Chunqiang

    2016-04-01

    Dynamic responses of a carriage under excitation with the German high-speed low-interference track spectrum together with the air pressure pulse generated as high-speed trains passing each other are investigated with a multi-body dynamics method. The variations of degrees of freedom (DOFs: horizontal movement, roll angle, and yaw angle), the lateral wheel-rail force, the derailment coefficient, and the rate of wheel load reduction with time when two carriages meet in open air are obtained and compared with the results of a single train travelling at specified speeds. Results show that the rate of wheel load reduction increases with the increase of train speed and meets some safety standard at a certain speed, but exceeding the value of the rate of wheel load reduction does not necessarily mean derailment. The evaluation standard of the rate of wheel load reduction is somewhat conservative and may be loosened. The pressure pulse has significant effects on the train DOFs, and the evaluations of these safety indexes are strongly suggested in practice. The pressure pulse has a limited effect on the derailment coefficient and the lateral wheel-rail force, and, thus, their further evaluations may be not necessary.

  17. Time of flight measurement of speed of sound in air with a computer sound card

    NASA Astrophysics Data System (ADS)

    Aljalal, Abdulaziz

    2014-11-01

    A computer sound card and freely available audio editing software are used to measure accurately the speed of sound in air using the time-of-flight method. In addition to speed of sound measurement, inversion behaviour upon reflection from an open and closed end of a pipe is demonstrated. Also, it is demonstrated that the reflection at an open end of a pipe occurs slightly outside the pipe. The equipment needed is readily available to any student with access to a microphone, loudspeaker and computer.

  18. Air speeds of migrating birds observed by ornithodolite and compared with predictions from flight theory.

    PubMed

    Pennycuick, C J; Åkesson, Susanne; Hedenström, Anders

    2013-09-01

    We measured the air speeds of 31 bird species, for which we had body mass and wing measurements, migrating along the east coast of Sweden in autumn, using a Vectronix Vector 21 ornithodolite and a Gill WindSonic anemometer. We expected each species' average air speed to exceed its calculated minimum-power speed (Vmp), and to fall below its maximum-range speed (Vmr), but found some exceptions to both limits. To resolve these discrepancies, we first reduced the assumed induced power factor for all species from 1.2 to 0.9, attributing this to splayed and up-turned primary feathers, and then assigned body drag coefficients for different species down to 0.060 for small waders, and up to 0.12 for the mute swan, in the Reynolds number range 25 000-250 000. These results will be used to amend the default values in existing software that estimates fuel consumption in migration, energy heights on arrival and other aspects of flight performance, using classical aeronautical theory. The body drag coefficients are central to range calculations. Although they cannot be measured on dead bird bodies, they could be checked against wind tunnel measurements on living birds, using existing methods.

  19. Air speeds of migrating birds observed by ornithodolite and compared with predictions from flight theory.

    PubMed

    Pennycuick, C J; Åkesson, Susanne; Hedenström, Anders

    2013-09-01

    We measured the air speeds of 31 bird species, for which we had body mass and wing measurements, migrating along the east coast of Sweden in autumn, using a Vectronix Vector 21 ornithodolite and a Gill WindSonic anemometer. We expected each species' average air speed to exceed its calculated minimum-power speed (Vmp), and to fall below its maximum-range speed (Vmr), but found some exceptions to both limits. To resolve these discrepancies, we first reduced the assumed induced power factor for all species from 1.2 to 0.9, attributing this to splayed and up-turned primary feathers, and then assigned body drag coefficients for different species down to 0.060 for small waders, and up to 0.12 for the mute swan, in the Reynolds number range 25 000-250 000. These results will be used to amend the default values in existing software that estimates fuel consumption in migration, energy heights on arrival and other aspects of flight performance, using classical aeronautical theory. The body drag coefficients are central to range calculations. Although they cannot be measured on dead bird bodies, they could be checked against wind tunnel measurements on living birds, using existing methods. PMID:23804440

  20. Air speeds of migrating birds observed by ornithodolite and compared with predictions from flight theory

    PubMed Central

    Pennycuick, C. J.; Åkesson, Susanne; Hedenström, Anders

    2013-01-01

    We measured the air speeds of 31 bird species, for which we had body mass and wing measurements, migrating along the east coast of Sweden in autumn, using a Vectronix Vector 21 ornithodolite and a Gill WindSonic anemometer. We expected each species’ average air speed to exceed its calculated minimum-power speed (Vmp), and to fall below its maximum-range speed (Vmr), but found some exceptions to both limits. To resolve these discrepancies, we first reduced the assumed induced power factor for all species from 1.2 to 0.9, attributing this to splayed and up-turned primary feathers, and then assigned body drag coefficients for different species down to 0.060 for small waders, and up to 0.12 for the mute swan, in the Reynolds number range 25 000–250 000. These results will be used to amend the default values in existing software that estimates fuel consumption in migration, energy heights on arrival and other aspects of flight performance, using classical aeronautical theory. The body drag coefficients are central to range calculations. Although they cannot be measured on dead bird bodies, they could be checked against wind tunnel measurements on living birds, using existing methods. PMID:23804440

  1. Irrigation system equipped on a high-speed air drill--technical note.

    PubMed

    Tsuzuki, T; Yanai, H; Kukita, C; Samejima, H; Shinyama, Y

    1998-03-01

    An irrigation system which can easily be applied to the conventional high-speed air drill was developed to allow simultaneous irrigation during micro-drilling. The irrigation system is constructed with a tube of 0.8 mm outer diameter and supporting rings. Irrigation is entirely coordinated with drilling by a single foot switch. The tube of the system ejects normal saline intermittently toward the cutter bar tip. Use of this system in skull base surgery showed that effective irrigation and a clean operative field was achieved even in a narrow space under the operating microscope, saline is ejected exactly on the point of drilling and over-heating does not occur so that heat-related damage to the local nerves and blood vessels is avoided. The system can easily be applied to any type of high-speed air drill by using supporting rings of the correct size. This irrigation system is particularly useful in microneurosurgery using the high-speed air drill. PMID:9597862

  2. Development of High Speed Inverter Rotary Compressor for the Air-conditioning System

    NASA Astrophysics Data System (ADS)

    Kang, Seoung-Min; Yang, Eun-soo; Shin, Jin-Ung; Park, Joon-Hong; Lee, Se-Dong; Ha, Jong-Hun; Son, Young-Boo; Lee, Byeong-Chul

    2015-08-01

    In order to meet the various operating loads of an air-conditioning system, an inverter compressor with a wide operational range is necessary. One of the ways to achieve a wide operation range is to drive a small capacity compressor at high speed. Moreover, it is possible to maximize the efficiency in part-load operation condition close to actual operating conditions and to reduce the cost by compact design of a small capacity compressor. In addition, the shortage of maximum capacity, due to the small rated capacity, is covered through high speed operation. However, in general, if the compressor operates at high speed, problems occurs such as reduced efficiency due to friction, increased noise, increased amount of oil discharge and decreased durability of the main components. In order to solve these problems the following have been investigated: optimized dimension parameters of the compression chamber, enhanced shaft design and the structure for the reduction of oil discharge and noise at high speed operation. Finally the high speed inverter rotary compressor with high efficiency and more compact size has been developed as compared with the conventional rotary compressor.

  3. Incorporation Of Air Into The Campanian Ignimbrite Pyroclastic Density Current

    NASA Astrophysics Data System (ADS)

    Ort, M. H.; Giordano, G.; Zanella, E.; Isaia, R.

    2015-12-01

    Knowing the temperature of emplacement of an ignimbrite can tell us how much cooling air it incorporated during eruption and transport. Currents that incorporate cool matter (air, water, cold clasts) cool more than those that do not. Lithic fragments record the maximum temperature they reached, up to their maximum unblocking temperature. Studies of large ignimbrites (e.g. Cerro Galan Ignimbrite) emplaced by dense currents show they do not cool very much, with emplacement temperatures often above 580 oC. Smaller currents, such as those from Vesuvius and Colima, lose significant heat in the eruption column, and then lose some, but less, heat as they travel laterally. The amount of atmosphere incorporated by large dilute currents is not known. The ~40 ka Campanian Ignimbrite (CI) erupted from the Campi Flegrei caldera near Naples, Italy, and extends to ~75 km from the caldera. The CI was emplaced from a density-stratified current with a dilute transport system and a denser depositional system that overtopped 1600-m-high ridges, with the depositional system re-forming on the far side. Modeling of dilute currents shows that they can pass over obstacles ~1.5 times their thickness without losing momentum, which implies the CI current was >1 km thick. Much of that dilute current was gas, but how much was atmospheric? Partial thermal demagnetization of lithic clasts allows the identification of the temperature of emplacement. We sampled lithic fragments from the CI in 13 locations from proximal to distal along several azimuths. The current passed over 30-35 km of sea to get to two sites. Partial thermal demagnetization of 10 specimens from each site show that they were heated and deposited above 580 oC, the unblocking temperature of magnetite, implying the temperature of emplacement was at or above this temperature. The CI is poor in lithic clasts (<1% in most places) and evidence of non-magmatic water in the outflow sheet is absent. We suggest the CI current was a large

  4. Theoretical Analysis and Optimum Design of High Speed Air Film Thrust Bearings

    NASA Astrophysics Data System (ADS)

    Hashimoto, Hiromu; Ochiai, Masayuki; Nanba, Tadashi

    Hydrodynamic air film thrust bearings are widely used for very high speed, lightly loaded rotating machinery such as gas expander, compressor, gyroscope and business machines, etc. In the design of hydrodynamic air film thrust bearings, it is of cardinal importance to enhance the friction and stability capacities of air films for keeping the minimum friction loss within a particular level and for minimizing the vibration due to external excitations. Among various types of hydrodynamic air film thrust bearings, spiral and herring bone types of grooved bearings have an advantage of high stability and load carrying capacity, but the characteristics of the bearings depend on many design parameters. Therefore, when these parameters are designed suitably, it is expected to improve considerably the friction and stability characteristics of the bearings. In this paper, the optimum design methodology is presented to minimize the friction torque and also to maximize the stiffness of air film for spiral and herring bone types of grooved air film thrust bearings, and the applicability of the methodology is verified experimentally.

  5. Computer modeling of the sensitivity of a laser water vapor sensor to variations in temperature and air speed

    NASA Technical Reports Server (NTRS)

    Tucker, George F.

    1994-01-01

    Currently, there is disagreement among existing methods of determining atmospheric water vapor concentration at dew-points below -40 C. A major source of error is wall effects which result from the necessity of bringing samples into the instruments. All of these instruments also have response times on the order of seconds. NASA Langley is developing a water vapor sensor which utilizes the absorption of the infrared radiation produced by a diode laser to estimate water vapor concentration. The laser beam is directed through an aircraft window to a retroreflector located on an engine. The reflected beam is detected by an infrared detector located near the laser. To maximize signal to noise, derivative signals are analyzed. By measuring the 2f/DC signal and correcting for ambient temperature, atmospheric pressure and air speed (which results in a Doppler shifting of the laser beam), the water vapor concentration can be retrieved. Since this is an in situ measurement there are no wall effects and measurements can be made at a rate of more than 20 per second. This allows small spatial variations of water vapor to be studied. In order to study the sensitivity of the instrument to variations in temperature and air speed, a computer program which generated the 2f, 3f, 4f, DC and 2f/DC signals of the instrument as a function of temperature, pressure and air speed was written. This model was used to determine the effect of errors in measurement of the temperature and air speed on the measured water vapor concentration. Future studies will quantify the effect of pressure measurement errors, which are expected to be very small. As a result of these studied, a retrieval algorithm has been formulated, and will be applied to data taken during the PEM-West atmospheric science field mission. Spectroscopic studies of the water vapor line used by the instrument will be used to refine this algorithm. To prepare for these studies, several lasers have been studied to determine their

  6. Efficient Computation of Separation-Compliant Speed Advisories for Air Traffic Arriving in Terminal Airspace

    NASA Technical Reports Server (NTRS)

    Sadovsky, Alexander V.; Davis, Damek; Isaacson, Douglas R.

    2012-01-01

    A class of problems in air traffic management asks for a scheduling algorithm that supplies the air traffic services authority not only with a schedule of arrivals and departures, but also with speed advisories. Since advisories must be finite, a scheduling algorithm must ultimately produce a finite data set, hence must either start with a purely discrete model or involve a discretization of a continuous one. The former choice, often preferred for intuitive clarity, naturally leads to mixed-integer programs, hindering proofs of correctness and computational cost bounds (crucial for real-time operations). In this paper, a hybrid control system is used to model air traffic scheduling, capturing both the discrete and continuous aspects. This framework is applied to a class of problems, called the Fully Routed Nominal Problem. We prove a number of geometric results on feasible schedules and use these results to formulate an algorithm that attempts to compute a collective speed advisory, effectively finite, and has computational cost polynomial in the number of aircraft. This work is a first step toward optimization and models refined with more realistic detail.

  7. Development of the High Speed Air Drop Container (HISAC): Status report

    SciTech Connect

    Cyrus, J.D.; Thibault, G.W.

    1989-01-01

    This paper discusses the development of the High Speed Air Drop Container (HISAC). The HISAC is an aerodynamically configured cargo container which will be transported and delivered as an external store by high performance tactical aircraft. It will be used to resupply ground forces with up to 500 pounds of equipment and supplies at release speeds up to Mach 0.95 and at altitudes as low as 300 feet above ground level (AGL). The HISAC design requirements are presented and the development approach is discussed. The store design is presented in detail and results of numerous tests are discussed. The parachute system design and testing is covered but not in detail, as this is the subject of another technical paper. Finally, the present status of the development program is discussed along with the future direction of the program. 5 refs., 10 figs., 3 tabs.

  8. High-speed impact test of an air-transportable plutonium nitrate shipping container

    SciTech Connect

    Yoshimura, H.R.; Pope, R.B.; Leisher, W.B.; Joseph, B.J.

    1980-04-01

    To obtain information on package response for comparison with other test environments, a high-speed impact test was performed on a modified Federal Republic of Germany 18B plutonium nitrate air-transportable container. The container, modified with reinforcing rings for improved crush resistance around the inner tube assembly, was impacted at a velocity of 137 m/s onto an unyielding surface. Substantial crushing of the foam overpack and extensive deformation of the container cavity occurred, causing release of the liquid surrogate contents from the titanium shipping container. The container damage resulting from the high-speed pulldown test was more severe than that from a 185-m free fall onto a semirigid surface by a similar container or the crush environment produced by a 9-m drop of a 2-Mg block onto the container resting on an unyielding surface.

  9. The 90 deg Acoustic Spectrum of a High Speed Air Jet

    NASA Technical Reports Server (NTRS)

    Goldstein, Marvin E.

    2004-01-01

    Tam and Auriault successfully predicted the acoustic spectrum at 90deg to the axis of a high speed air jet by using an acoustic equation derived from ad hoc kinetic theory-type arguments. The present paper shows that similar predictions can be obtained by using a rigorous acoustic analogy approach together with actual measurements of the relevant acoustic source correlations. This puts the result on a firmer basis and enables its extension to new situations and to the prediction of sound at other observation angles.

  10. On the Resistance of the Air at High Speeds and on the Automatic Rotation of Projectiles

    NASA Technical Reports Server (NTRS)

    Riabouchinski, D

    1921-01-01

    Here, the laws governing the flow of a compressible fluid through an opening in a thin wall are applied to the resistance of the air at high speeds, especially as applied to the automatic rotation of projectiles. The instability which we observe in projectiles shot into the air without being given a moment of rotation about their axis of symmetry, or without stabilizing planes, is a phenomenon of automatic rotation. It is noted that we can prevent this phenomenon of automatic rotation by bringing the center of gravity sufficiently near one end, or by fitting the projectile with stabilizing planes or a tail. The automatic rotation of projectiles is due to the suction produced by the systematic formation of vortices behind the extremity of the projectile moving with the wind.

  11. Qualitative evaluation of a flush air data system at transonic speeds and high angles of attack

    NASA Technical Reports Server (NTRS)

    Larson, Terry J.; Whitmore, Stephen A.; Ehernberger, L. J.; Johnson, J. Blair; Siemers, Paul M., III

    1987-01-01

    Flight tests were performed on an F-14 aircraft to evaluate the use of flush pressure orifices on the nose section for obtaining air data at transonic speeds over a large range of flow angles. This program was part of a flight test and wind tunnel program to assess the accuracies of such systems for general use on aircraft. It also provided data to validate algorithms developed for the shuttle entry air data system designed at NASA Langley. Data were obtained for Mach numbers between 0.60 and 1.60, for angles of attack up to 26.0 deg, and for sideslip angles up to 11.0 deg. With careful calibration, a flush air data system with all flush orifices can provide accurate air data information over a large range of flow angles. Several orificies on the nose cap were found to be suitable for determination of stagnation pressure. Other orifices on the nose section aft of the nose cap were shown to be suitable for determination of static pressure. Pairs of orifices on the nose cap provided the most sensitive measurements for determining angles of attack and sideslip, although orifices located farther aft on the nose section could also be used.

  12. Purification of rutin and nicotiflorin from the flowers of Edgeworthia chrysantha Lindl. by high-speed counter-current chromatography.

    PubMed

    Tong, Shengqiang; Yan, Jizhong; Chen, Gang; Lou, Jianzhong

    2009-01-01

    An ethanol extract of air-dried flowers of Edgeworthia chrysantha Lindl. was partitioned between water and petroleum, ethyl acetate, and n-butanol. The n-butanol extraction was initially purified by silica gel column chromatography to give a partially purified sample. The bioactive compound rutin, along with nicotiflorin, were successfully separated from the partially purified sample by high-speed counter-current chromatography. The two compounds were isolated from the plant of Edgeworthia genus for the first time. The two-phase solvent system used was composed of ethyl acetate-n-butanol-water at an optimized ratio of 4:1:5 (v/v/v). High-speed counter-current chromatography yielded, from 108 mg of the partially purified extract, 53 mg rutin and 32 mg nicotiflorin with 92.5% and 92.2% recovery, with each at over 96.5% purity by high-performance liquid chromatography analysis. Their structures were identified by 1H NMR and 13C NMR. PMID:19476699

  13. Towards increased speed computations in 3D moving eddy current finite element modelling

    SciTech Connect

    Allen, N.; Rodger, D.; Coles, P.C.; Street, S.; Leonard, P.J.

    1995-11-01

    Attractive and drag forces on such devices as magnetically levitated (MAGLEV) vehicles and magnetic bearings are crucially dependent on induced eddy currents. Here, a finite element scheme used to model eddy current problems with motional velocity is described here. The formulation is a variation on the A {minus} {psi} method. An additional Minkowski-transformation term is required to take into account the velocity. However, computational instability arises when the velocity increases to the point that the first order velocity terms severely dominate the second order diffusion terms. The method presented here uses upwinding to help regain stability. An additional degree of stability is inserted at higher speeds by using a lower speed result as an initial vector. This leads to a reduced permeability in saturated regions which counter-balances to some extent the increase in velocity. The method is validated by experimental measurement.

  14. RECORDING FLAME SPEED DATA OF FUEL AND AIR RATIO MIXTURES - THE HORIZONTAL GLASS TUBE IS FILLED WITH

    NASA Technical Reports Server (NTRS)

    1949-01-01

    RECORDING FLAME SPEED DATA OF FUEL AND AIR RATIO MIXTURES - THE HORIZONTAL GLASS TUBE IS FILLED WITH A HOMOGENOUS MIXTURE OF FUEL AND AIR - THE RATE OF FLAME TRAVEL IS PICKED UP BY PHOTO CELLS SHOWN ABOVE THE TUBE AND RECORDED ON THE ELECTRONIC TIME

  15. A Comparative Study of Sound Speed in Air at Room Temperature between a Pressure Sensor and a Sound Sensor

    ERIC Educational Resources Information Center

    Amrani, D.

    2013-01-01

    This paper deals with the comparison of sound speed measurements in air using two types of sensor that are widely employed in physics and engineering education, namely a pressure sensor and a sound sensor. A computer-based laboratory with pressure and sound sensors was used to carry out measurements of air through a 60 ml syringe. The fast Fourier…

  16. Characterization of near-bed sediment transport in air and water by high-speed video

    NASA Astrophysics Data System (ADS)

    Martin, C. S.; Hamm, N. T.; Cushman-Roisin, B.; Dade, W. B.

    2010-12-01

    Near-bed sediment transport comprises a large fraction of the total mass flux of environmental flows, yet is difficult to characterize at fine scales without disturbing the flow. Particle-tracking velocimetry by means of high-speed video has proven to be an effective technique for quantifying particle behavior under this constraint. We present here results of experiments examining: i) the vertical structure of mass and momentum and ii) initial properties of particle trajectories within a layer of sediment transport immediately above a bed of loose grains in channel flows. Observations were conducted in both air and water of test particles with the density of quartz and with median diameters that ranged from 30 µm to 600 µm. Analysis of such a wide range of sediment transport conditions by the same method permits an evaluation of the fundamental structure of the near-bed sediment transport layer, including particle concentration and particle velocity. With appropriate normalization, self-consistent structure is identified for all particles in air, medium sand in water, and fine sand and silt in water. The integral values by which the data were normalized are found to be consistent with the relevant physical properties of the sediment transporting flow. This study advances the use of high-speed videography as a method by which to investigate the detailed mechanics of particle motion in a near-bed boundary layer, which in turn, can provide boundary conditions used for modeling sediment transport in a variety of applications.

  17. Speed-dependent emission of air pollutants from gasoline-powered passenger cars.

    PubMed

    Jung, Sungwoon; Lee, Meehye; Kim, Jongchoon; Lyu, Youngsook; Park, Junhong

    2011-01-01

    In Korea emissions from motor vehicles are a major source of air pollution in metropolitan cities, and in Seoul a large proportion of the vehicle fleet is made up of gasoline-powered passenger cars. The carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NOx) and carbon dioxide (CO2) contained in the exhaust emissions from 76 gasoline-powered passenger cars equipped with three-way catalysts has been assessed by vehicle speed, vehicle mileage and model year. The results show that CO, HC, NOx and CO2 emissions remained almost unchanged at higher speeds but decreased rapidly at lower speeds. While a reduction in CO, HC and NOx emissions was noticeable in vehicles of recent manufacture and lower mileage, CO2 emissions were found to be insensitive to vehicle mileage, but strongly dependent on gross vehicle weight. Lower emissions from more recent gasoline-powered vehicles arose mainly from improvements in three-way catalytic converter technology following strengthened emission regulations. The correlation between CO2 emission and fuel consumption has been investigated with a view to establishing national CO2 emission standards for Korea.

  18. Speed-dependent emission of air pollutants from gasoline-powered passenger cars.

    PubMed

    Jung, Sungwoon; Lee, Meehye; Kim, Jongchoon; Lyu, Youngsook; Park, Junhong

    2011-01-01

    In Korea emissions from motor vehicles are a major source of air pollution in metropolitan cities, and in Seoul a large proportion of the vehicle fleet is made up of gasoline-powered passenger cars. The carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen (NOx) and carbon dioxide (CO2) contained in the exhaust emissions from 76 gasoline-powered passenger cars equipped with three-way catalysts has been assessed by vehicle speed, vehicle mileage and model year. The results show that CO, HC, NOx and CO2 emissions remained almost unchanged at higher speeds but decreased rapidly at lower speeds. While a reduction in CO, HC and NOx emissions was noticeable in vehicles of recent manufacture and lower mileage, CO2 emissions were found to be insensitive to vehicle mileage, but strongly dependent on gross vehicle weight. Lower emissions from more recent gasoline-powered vehicles arose mainly from improvements in three-way catalytic converter technology following strengthened emission regulations. The correlation between CO2 emission and fuel consumption has been investigated with a view to establishing national CO2 emission standards for Korea. PMID:21970159

  19. Filtering and Control of High Speed Motor Current in a Flywheel Energy Storage System

    NASA Technical Reports Server (NTRS)

    Kenny, Barbara H.; Santiago, Walter

    2004-01-01

    The NASA Glenn Research Center has been developing technology to enable the use of high speed flywheel energy storage units in future spacecraft for the last several years. An integral part of the flywheel unit is the three phase motor/generator that is used to accelerate and decelerate the flywheel. The motor/generator voltage is supplied from a pulse width modulated (PWM) inverter operating from a fixed DC voltage supply. The motor current is regulated through a closed loop current control that commands the necessary voltage from the inverter to achieve the desired current. The current regulation loop is the innermost control loop of the overall flywheel system and, as a result, must be fast and accurate over the entire operating speed range (20,000 to 60,000 rpm) of the flywheel. The voltage applied to the motor is a high frequency PWM version of the DC bus voltage that results in the commanded fundamental value plus higher order harmonics. Most of the harmonic content is at the switching frequency and above. The higher order harmonics cause a rapid change in voltage to be applied to the motor that can result in large voltage stresses across the motor windings. In addition, the high frequency content in the motor causes sensor noise in the magnetic bearings that leads to disturbances for the bearing control. To alleviate these problems, a filter is used to present a more sinusoidal voltage to the motor/generator. However, the filter adds additional dynamics and phase lag to the motor system that can interfere with the performance of the current regulator. This paper will discuss the tuning methodology and results for the motor/generator current regulator and the impact of the filter on the control. Results at speeds up to 50,000 rpm are presented.

  20. Gestational Diabetes and Preeclampsia in Association with Air Pollution at Levels below Current Air Quality Guidelines

    PubMed Central

    Jakobsson, Kristina; Tinnerberg, Håkan; Rignell-Hydbom, Anna; Rylander, Lars

    2013-01-01

    Background: Several studies have estimated associations between air pollution and birth outcomes, but few have evaluated potential effects on pregnancy complications. Objective: We investigated whether low-level exposure to air pollution is associated with gestational diabetes and preeclampsia. Methods: High-quality registry information on 81,110 singleton pregnancy outcomes in southern Sweden during 1999–2005 was linked to individual-level exposure estimates with high spatial resolution. Modeled exposure to nitrogen oxides (NOx), expressed as mean concentrations per trimester, and proximity to roads of different traffic densities were used as proxy indicators of exposure to combustion-related air pollution. The data were analyzed by logistic regression, with and without adjusting for potential confounders. Results: The prevalence of gestational diabetes increased with each NOx quartile, with an adjusted odds ratio (OR) of 1.69 (95% CI: 1.41, 2.03) for the highest (> 22.7 µg/m3) compared with the lowest quartile (2.5–8.9 µg/m3) of exposure during the second trimester. The adjusted OR for acquiring preeclampsia after exposure during the third trimester was 1.51 (1.32, 1.73) in the highest quartile of NOx compared with the lowest. Both outcomes were associated with high traffic density, but ORs were significant for gestational diabetes only. Conclusion: NOx exposure during pregnancy was associated with gestational diabetes and preeclampsia in an area with air pollution levels below current air quality guidelines. PMID:23563048

  1. A single/two-phase, regenerative, variable speed, induction motor drive with sinusoidal input current

    SciTech Connect

    Rahman, M.F.; Zhong, L.

    1995-12-31

    The single phase induction motor with two windings, main and auxiliary, is probably the most widely used motor in the world. The mains operated single-phase motor usually operates at low power factor, low efficiency and at fixed speed. At most, two or three fixed speeds are provided when required, through manual intervention. Such fixed speed operation hinders product designers from incorporating many interesting and useful features in their products. The present concern on harmonic pollution of the supply and low power factor operation, as embodied in the recent IEC555-2 standard, also calls for power factor correction measures to be included in applications where a single phase motor is used. This paper presents a variable speed single-phase motor (with two windings) drive that utilizes just six switches as found in the emerging intelligent power modules (IPM). Just one integrated module with six switches serves to implement the input rectifier with sinusoidal input current, and the two-phase VSI or CSI inverter to drive the two phases of the motor with balanced ampere-turns. The input rectifier is also reversible, so that the motor can be braked with energy return to the mains, thus operating with high efficiency at all times.

  2. Theoretical speed and current density limits for different types of electrical brushes

    NASA Astrophysics Data System (ADS)

    Kuhlmann-Wilsdorf, D.

    1984-03-01

    Theoretical performance limits based on the criterion of flash temperature are investigated for monolithic Ag-C brushes, Cu-on-Cu brushes with elastic contact spots, and 'QM' brushes (Quantum Mechanical brushes with ultrathin metal fibers), in which ordinary current conduction is significantly supplemented by electron tunneling peripherally about the contact spots. Equations are developed for the contact spot radii and heat input rates for frictional and electrical heating at the contact spots. Typical data for the flash temperatures are calculated for the high-speed approximation for plastic and elastic contact spots. The low-speed approximation is used for QM brushes. It is concluded that metal fiber and/or QM brushes may represent the best solution to the brush problem for electromagnetic launching.

  3. High-resolution daily gridded datasets of air temperature and wind speed for Europe

    NASA Astrophysics Data System (ADS)

    Brinckmann, S.; Krähenmann, S.; Bissolli, P.

    2015-08-01

    New high-resolution datasets for near surface daily air temperature (minimum, maximum and mean) and daily mean wind speed for Europe (the CORDEX domain) are provided for the period 2001-2010 for the purpose of regional model validation in the framework of DecReg, a sub-project of the German MiKlip project, which aims to develop decadal climate predictions. The main input data sources are hourly SYNOP observations, partly supplemented by station data from the ECA&D dataset (http://www.ecad.eu). These data are quality tested to eliminate erroneous data and various kinds of inhomogeneities. Grids in a resolution of 0.044° (5 km) are derived by spatial interpolation of these station data into the CORDEX area. For temperature interpolation a modified version of a regression kriging method developed by Krähenmann et al. (2011) is used. At first, predictor fields of altitude, continentality and zonal mean temperature are chosen for a regression applied to monthly station data. The residuals of the monthly regression and the deviations of the daily data from the monthly averages are interpolated using simple kriging in a second and third step. For wind speed a new method based on the concept used for temperature was developed, involving predictor fields of exposure, roughness length, coastal distance and ERA Interim reanalysis wind speed at 850 hPa. Interpolation uncertainty is estimated by means of the kriging variance and regression uncertainties. Furthermore, to assess the quality of the final daily grid data, cross validation is performed. Explained variance ranges from 70 to 90 % for monthly temperature and from 50 to 60 % for monthly wind speed. The resulting RMSE for the final daily grid data amounts to 1-2 °C and 1-1.5 m s-1 (depending on season and parameter) for daily temperature parameters and daily mean wind speed, respectively. The datasets presented in this article are published at http://dx.doi.org/10.5676/DWD_CDC/DECREG0110v1.

  4. High-resolution daily gridded data sets of air temperature and wind speed for Europe

    NASA Astrophysics Data System (ADS)

    Brinckmann, Sven; Krähenmann, Stefan; Bissolli, Peter

    2016-10-01

    New high-resolution data sets for near-surface daily air temperature (minimum, maximum and mean) and daily mean wind speed for Europe (the CORDEX domain) are provided for the period 2001-2010 for the purpose of regional model validation in the framework of DecReg, a sub-project of the German MiKlip project, which aims to develop decadal climate predictions. The main input data sources are SYNOP observations, partly supplemented by station data from the ECA&D data set (http://www.ecad.eu). These data are quality tested to eliminate erroneous data. By spatial interpolation of these station observations, grid data in a resolution of 0.044° (≈ 5km) on a rotated grid with virtual North Pole at 39.25° N, 162° W are derived. For temperature interpolation a modified version of a regression kriging method developed by Krähenmann et al.(2011) is used. At first, predictor fields of altitude, continentality and zonal mean temperature are used for a regression applied to monthly station data. The residuals of the monthly regression and the deviations of the daily data from the monthly averages are interpolated using simple kriging in a second and third step. For wind speed a new method based on the concept used for temperature was developed, involving predictor fields of exposure, roughness length, coastal distance and ERA-Interim reanalysis wind speed at 850 hPa. Interpolation uncertainty is estimated by means of the kriging variance and regression uncertainties. Furthermore, to assess the quality of the final daily grid data, cross validation is performed. Variance explained by the regression ranges from 70 to 90 % for monthly temperature and from 50 to 60 % for monthly wind speed. The resulting RMSE for the final daily grid data amounts to 1-2 K and 1-1.5 ms-1 (depending on season and parameter) for daily temperature parameters

  5. Air Quality Study Using Satellites - Current Capability and Future Plans

    NASA Technical Reports Server (NTRS)

    Bhartia, Pawan K.; Joiner, Joanna; Gleason, James; Liu, Xiong; Torres, Omar; Krotkov, Nickolay; Ziemke, Jerry; Chandra, Sushil

    2008-01-01

    Satellite instruments have had great success in monitoring the stratospheric ozone and in understanding the processes that control its daily to decadal scale variations. This field is now reaching its zenith with a number of satellite instruments from the US, Europe and Canada capping several decades of active research in this field. The primary public policy imperative of this research was to make reliable prediction of increases in biologically active surface UV radiation due to human activity. By contrast retrieval from satellite data of atmospheric constituents and photo-chemically active radiation that affect air quality is a new and growing field that is presenting us with unique challenges in measurement and data interpretation. A key distinction compared to stratospheric sensors is the greatly enhanced role of clouds, aerosols, and surfaces (CAS) in determining the quality and quantity of useful data that is available for air quality research. In our presentation we will use data from several sensors that are currently flying on the A-train satellite constellation, including OMI, MODIS, CLOUDSAT, and CALIPSO, to highlight that CAS can have both positive and negative effects on the information content of satellite measurements. This is in sharp contrast to other fields of remote sensing where CAS are usually considered an interference except in those cases when they are the primary subject of study. Our analysis has revealed that in the reflected wavelengths one often sees much further down into the atmosphere, through most cirrus, than one does in the emitted wavelengths. The lower level clouds provide a nice background against which one can track long-range transport of trace gases and aerosols. In addition, differences in trace gas columns estimated over cloudy and adjacent clear pixels can be used to measure boundary layer trace gases. However, in order to take full advantage of these features it will be necessary to greatly advance our understanding of

  6. AGARD WG13 aerodynamics of high speed air intakes: Assessment of CFD results

    NASA Technical Reports Server (NTRS)

    Bissinger, N. C.; Benson, T. J.; Bradley, R. G., Jr.

    1992-01-01

    A brief review of the work accomplished by the numerical subgroup of AGARD Working Group 13 on the aerodynamics of high speed air intakes is presented. This work comprised the selection of test cases for which experimental data were available. The test cases were chosen to range in complexity from normal-shock/boundary-layer interaction to full forebody-inlet combinations. Computations for these test cases were solicited from a large number of organizations and individual researchers within the NATO countries. The computation methods reached from Euler solvers (with and without boundary layer corrections) to full Reynolds averaged Navier-Stokes codes. The group compared these results with the test data available for each test case. A short overview of the CFD methods employed, a description of the test cases selected, and some of the comparisons between CFD solutions and test data are presented. The conclusions and recommendations drawn from this assessment are given.

  7. High-Speed Current dq PI Controller for Vector Controlled PMSM Drive

    PubMed Central

    Reaz, Mamun Bin Ibne; Rahman, Labonnah Farzana; Chang, Tae Gyu

    2014-01-01

    High-speed current controller for vector controlled permanent magnet synchronous motor (PMSM) is presented. The controller is developed based on modular design for faster calculation and uses fixed-point proportional-integral (PI) method for improved accuracy. Current dq controller is usually implemented in digital signal processor (DSP) based computer. However, DSP based solutions are reaching their physical limits, which are few microseconds. Besides, digital solutions suffer from high implementation cost. In this research, the overall controller is realizing in field programmable gate array (FPGA). FPGA implementation of the overall controlling algorithm will certainly trim down the execution time significantly to guarantee the steadiness of the motor. Agilent 16821A Logic Analyzer is employed to validate the result of the implemented design in FPGA. Experimental results indicate that the proposed current dq PI controller needs only 50 ns of execution time in 40 MHz clock, which is the lowest computational cycle for the era. PMID:24574913

  8. High-Speed Rainbow Schlieren Deflectometry Analysis of Helium Jets Flowing into Air for Microgravity Applications

    NASA Technical Reports Server (NTRS)

    Leptuch, Peter A.

    2002-01-01

    The flow phenomena of buoyant jets have been analyzed by many researchers in recent years. Few, however have studied jets in microgravity conditions, and the exact nature of the flow under these conditions has until recently been unknown. This study seeks to extend the work done by researchers at the university of Oklahoma in examining and documenting the behavior of helium jets in micro-gravity conditions. Quantitative rainbow schlieren deflectometry data have been obtained for helium jets discharging vertically into quiescent ambient air from tubes of several diameters at various flow rates using a high-speed digital camera. These data have obtained before, during and after the onset of microgravity conditions. High-speed rainbow schlieren deflectometry has been developed for this study with the installation and use of a high-speed digital camera and modifications to the optical setup. Higher temporal resolution of the transitional phase between terrestrial and micro-gravity conditions has been obtained which has reduced the averaging effect of longer exposure times used in all previous schlieren studies. Results include color schlieren images, color time-space images (temporal evolution images), frequency analyses, contour plots of hue and contour plots of helium mole fraction. The results, which focus primarily on the periods before and during the onset of microgravity conditions, show that the pulsation of the jets normally found in terrestrial gravity ("earth"-gravity) conditions cease, and the gradients in helium diminish to produce a widening of the jet in micro-gravity conditions. In addition, the results show that the disturbance propagate upstream from a downstream source.

  9. High-current quasi-square-wave millisecond light source for high-speed photography

    NASA Astrophysics Data System (ADS)

    Lin, Wenzheng; Jiang, Aibao; Zhuo, Meizhen

    1993-01-01

    A novel powerful strobe for high-speed photography is described which can replace the high power cw light source, to save energy and synchroflash with the camera. In this strobe, three- phase transformerless direct rectifier, high current SCR switch and pre-ionization technique are used so that the energy consumption goes down greatly, and its total weight is less than 25 Kg. Its principal parameters are as follows: average power, 50 KW; light emitting pulse width, 1 - 100 ms; pulse rise time, less than 0.05 ms; pulse fall time, less than 0.1 ms.

  10. Use of nose cap and fuselage pressure orifices for determination of air data for space shuttle orbiter below supersonic speeds

    NASA Technical Reports Server (NTRS)

    Larson, T. J.; Siemers, P. M., III

    1980-01-01

    Wind tunnel pressure measurements were acquired from orifices on a 0.1 scale forebody model of the space shuttle orbiter that were arranged in a preliminary configuration of the shuttle entry air data system (SEADS). Pressures from those and auxiliary orifices were evaluated for their ability to provide air data at subsonic and transonic speeds. The orifices were on the vehicle's nose cap and on the sides of the forebody forward of the cabin. The investigation covered a Mach number range of 0.25 to 1.40 and an angle of attack range from 4 deg. to 18 deg. An air data system consisting of nose cap and forebody fuselage orifices constitutes a complete and accurate air data system at subsonic and transonic speeds. For Mach numbers less than 0.80 orifices confined to the nose cap can be used as a complete and accurate air data system. Air data systems that use only flush pressure orifices can be used to determine basic air data on other aircraft at subsonic and transonic speeds.

  11. Experimental Study and CFD modeling of high speed water jets in air

    NASA Astrophysics Data System (ADS)

    Guha, Anirban; Barron, R. M.; Balachandar, R.

    2007-11-01

    High speed turbulent water jets are extensively used in industrial cleaning applications. They interact vigorously with the surrounding air and loose mass in the form of water droplets which moves along with the entrained air stream. The transfer of momentum to the surroundings reduces the jet velocity and thus the pressure at the impinging surface is significantly lower than the supply pressure. Laser Doppler Anemometer (LDA) measurements of velocity field and pressure measurements at different axial and radial locations were performed. The potential core of the jet was found to extend to around 100 nozzle diameters. The dynamic pressure along the centerline was found to decay linearly, which can be used to estimate the decay of water volume fraction along the centerline. An empirical formulation of mass transfer (in the form of droplets) from water phase to the surroundings has been developed and incorporated into the commercial CFD code FLUENT. The flow was simulated using the RNG k-ɛ turbulence model and Eulerian-Eulerian multiphase model. The predicted pressure distribution at the impinging surface was found to match closely with the experimental findings.

  12. High Speed High Resolution Current Comparator and its Application to Analog to Digital Converter

    NASA Astrophysics Data System (ADS)

    Sridhar, Ranjana; Pandey, Neeta; Bhattacharyya, Asok; Bhatia, Veepsa

    2016-06-01

    This paper introduces a high speed high resolution current comparator which includes the current differencing stage and employs non linear feedback in the gain stage. The usefulness of the proposed comparator is demonstrated by implementing a 3-bit current mode flash analog-to-digital converter (ADC). Simulation program with integrated circuit emphasis (SPICE) simulations have been carried out to verify theoretical proposition and performance parameters of both comparator and ADC are obtained using TSMC 0.18 µm CMOS technology parameters. The current comparator shows a resolution of ±5 nA and a delay of 0.86 ns for current difference of ±1 µA. The impact of process variation on proposed comparator propagation delay has been studied through Monte Carlo simulation and it is found that percentage change in propagation delay in best case is 1.3 % only and in worst case is 9 % only. The ADC exhibits an offset, gain error, differential nonlinearity (DNL) and integral nonlinearity (INL) of 0.102 µA, 0.99, -0.34 LSB and 0.0267 LSB, respectively. The impact of process variation on ADC has also been studied at different process corners.

  13. A High-Speed Adaptively-Biased Current-to-Current Front-End for SSPM Arrays

    NASA Astrophysics Data System (ADS)

    Zheng, Bob; Walder, Jean-Pierre; Lippe, Henrik vonder; Moses, William; Janecek, Martin

    Solid-state photomultiplier (SSPM) arrays are an interesting technology for use in PET detector modules due to their low cost, high compactness, insensitivity to magnetic fields, and sub-nanosecond timing resolution. However, the large intrinsic capacitance of SSPM arrays results in RC time constants that can severely degrade the response time, which leads to a trade-off between array size and speed. Instead, we propose a front-end that utilizes an adaptively biased current-to-current converter that minimizes the resistance seen by the SSPM array, thus preserving the timing resolution for both large and small arrays. This enables the use of large SSPM arrays with resistive networks, which creates position information and minimizes the number of outputs for compatibility with general PET multiplexing schemes. By tuning the bias of the feedback amplifier, the chip allows for precise control of the close-loop gain, ensuring stability and fast operation from loads as small as 50pF to loads as large as 1nF. The chip has 16 input channels, and 4 outputs capable of driving 100 n loads. The power consumption is 12mW per channel and 360mW for the entire chip. The chip has been designed and fabricated in an AMS 0.35um high-voltage technology, and demonstrates a fast rise-time response and low noise performances.

  14. 46 CFR 35.35-45 - Auxiliary steam, air, or electric current-B/ALL.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 1 2013-10-01 2013-10-01 false Auxiliary steam, air, or electric current-B/ALL. 35.35... Cargo Handling § 35.35-45 Auxiliary steam, air, or electric current—B/ALL. When discharging cargo from one or more barges, the towing vessel may furnish steam, air, or electric current for pumps on...

  15. 46 CFR 35.35-45 - Auxiliary steam, air, or electric current-B/ALL.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 1 2012-10-01 2012-10-01 false Auxiliary steam, air, or electric current-B/ALL. 35.35... Cargo Handling § 35.35-45 Auxiliary steam, air, or electric current—B/ALL. When discharging cargo from one or more barges, the towing vessel may furnish steam, air, or electric current for pumps on...

  16. 46 CFR 35.35-45 - Auxiliary steam, air, or electric current-B/ALL.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 1 2011-10-01 2011-10-01 false Auxiliary steam, air, or electric current-B/ALL. 35.35... Cargo Handling § 35.35-45 Auxiliary steam, air, or electric current—B/ALL. When discharging cargo from one or more barges, the towing vessel may furnish steam, air, or electric current for pumps on...

  17. 46 CFR 35.35-45 - Auxiliary steam, air, or electric current-B/ALL.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 1 2014-10-01 2014-10-01 false Auxiliary steam, air, or electric current-B/ALL. 35.35... Cargo Handling § 35.35-45 Auxiliary steam, air, or electric current—B/ALL. When discharging cargo from one or more barges, the towing vessel may furnish steam, air, or electric current for pumps on...

  18. 46 CFR 35.35-45 - Auxiliary steam, air, or electric current-B/ALL.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Auxiliary steam, air, or electric current-B/ALL. 35.35... Cargo Handling § 35.35-45 Auxiliary steam, air, or electric current—B/ALL. When discharging cargo from one or more barges, the towing vessel may furnish steam, air, or electric current for pumps on...

  19. Statistical Short-Range Guidance for Peak Wind Speed Forecasts at Edwards Air Force Base, CA

    NASA Technical Reports Server (NTRS)

    Dreher, Joseph; Crawford, Winifred; Lafosse, Richard; Hoeth, Brian; Burns, Kerry

    2008-01-01

    The peak winds near the surface are an important forecast element for Space Shuttle landings. As defined in the Shuttle Flight Rules (FRs), there are peak wind thresholds that cannot be exceeded in order to ensure the safety of the shuttle during landing operations. The National Weather Service Spaceflight Meteorology Group (SMG) is responsible for weather forecasts for all shuttle landings. They indicate peak winds are a challenging parameter to forecast. To alleviate the difficulty in making such wind forecasts, the Applied Meteorology Unit (AMTJ) developed a personal computer based graphical user interface (GUI) for displaying peak wind climatology and probabilities of exceeding peak-wind thresholds for the Shuttle Landing Facility (SLF) at Kennedy Space Center. However, the shuttle must land at Edwards Air Force Base (EAFB) in southern California when weather conditions at Kennedy Space Center in Florida are not acceptable, so SMG forecasters requested that a similar tool be developed for EAFB. Marshall Space Flight Center (MSFC) personnel archived and performed quality control of 2-minute average and 10-minute peak wind speeds at each tower adjacent to the main runway at EAFB from 1997- 2004. They calculated wind climatologies and probabilities of average peak wind occurrence based on the average speed. The climatologies were calculated for each tower and month, and were stratified by hour, direction, and direction/hour. For the probabilities of peak wind occurrence, MSFC calculated empirical and modeled probabilities of meeting or exceeding specific 10-minute peak wind speeds using probability density functions. The AMU obtained and reformatted the data into Microsoft Excel PivotTables, which allows users to display different values with point-click-drag techniques. The GUT was then created from the PivotTables using Visual Basic for Applications code. The GUI is run through a macro within Microsoft Excel and allows forecasters to quickly display and

  20. Influence of travel speed on spray deposition uniformity from an air-assisted variable-rate sprayer

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A newly developed LiDAR-guided air-assisted variable-rate sprayer for nursery and orchard applications was tested at various travel speeds to compare its spray deposition and coverage uniformity with constant-rate applications. Spray samplers, including nylon screens and water-sensitive papers (WSP)...

  1. In situ measurements of wind and current speed and relationship between output power and turbulence

    NASA Astrophysics Data System (ADS)

    Duran Medina, Olmo; Schmitt, François G.; Sentchev, Alexei; Calif, Rudy

    2015-04-01

    In a context of energy transition, wind and tidal energy are sources of clean energy with the potential of partially satisfying the growing demand. The main problem of this type of energy, and other types of renewable energy remains the discontinuity of the electric power produced in different scales, inducing large fluctuations also called intermittency. This intermittency of wind and tidal energy is inherent to the turbulent nature of wind and marine currents. We consider this intermittent power production in strong relation with the turbulent intermittency of the resource. The turbulence theory is multifractal energy cascades models, a classic in physics of turbulence. From earlier studies in atmospheric sciences, we learn that wind speed and the aggregate power output are intermittent and multifractal over a wide range of scales [Calif and Schmitt 2014]. We want to extend this study to a marine current turbine and compare the scaling properties for those renewable energy sources. We consider here coupling between simultaneous velocity time series and output power from a wind turbine and a marine current turbine. Wind turbine data were obtained from Denmark and marine current data from Western Scheldt, Belgium where a prototype of a vertical and horizontal marine current turbines are tested. After an estimation of their Fourier density power spectra, we study their scaling properties in Kolmogorov's theory and the framework of fully developed turbulence. Hence, we employ a Hilbert-based methodology, namely arbitrary-order Hilbert spectral analysis [Calif et al. 2013a, 2013b] to characterize the intermittent property of the wind and marine current velocity in order to characterize the intermittent nature of the fluid. This method is used in order to obtain the spectrum and the corresponding power law for non-linear and non-stationary time series. The goal is to study the non-linear transfer characteristics in a multi-scale and multi-intensity framework.

  2. Preparative separation of grape skin polyphenols by high-speed counter-current chromatography.

    PubMed

    Luo, Lanxin; Cui, Yan; Zhang, Shuting; Li, Lingxi; Li, Yuanyuan; Zhou, Peiyu; Sun, Baoshan

    2016-12-01

    To develop an efficient method for large preparation of various individual polyphenols from white grape skins (Fernão Pires; Vitis vinifera) by preparative high-speed counter-current chromatography (HSCCC) and preparative-HPLC, an optimized preparative HSCCC condition with two-phase solvent system composed of Hex-EtOAc-H2O (1:50:50, v/v) was used to separate grape skin polyphenols into various fractions. Both the tail-head and head-tail elution modes were used with a flow rate of 3.0ml/min and a rotary speed of 950rpm. Afterwards, a preparative-HPLC separation was applied to isolate individual polyphenols in each of the fractions from HSCCC. Total of 7 fractions (Fraction A to G) were obtained from grape skin extract by HSCCC. After preparative-HPLC isolation, fifteen individual compounds were obtained, most of which presented high yields and purity (all over 90%). The HSCCC method followed with preparative-HPLC appeared to be convenient and economical, constituting an efficient strategy for the isolation of grape skin polyphenols.

  3. Preparative separation of grape skin polyphenols by high-speed counter-current chromatography.

    PubMed

    Luo, Lanxin; Cui, Yan; Zhang, Shuting; Li, Lingxi; Li, Yuanyuan; Zhou, Peiyu; Sun, Baoshan

    2016-12-01

    To develop an efficient method for large preparation of various individual polyphenols from white grape skins (Fernão Pires; Vitis vinifera) by preparative high-speed counter-current chromatography (HSCCC) and preparative-HPLC, an optimized preparative HSCCC condition with two-phase solvent system composed of Hex-EtOAc-H2O (1:50:50, v/v) was used to separate grape skin polyphenols into various fractions. Both the tail-head and head-tail elution modes were used with a flow rate of 3.0ml/min and a rotary speed of 950rpm. Afterwards, a preparative-HPLC separation was applied to isolate individual polyphenols in each of the fractions from HSCCC. Total of 7 fractions (Fraction A to G) were obtained from grape skin extract by HSCCC. After preparative-HPLC isolation, fifteen individual compounds were obtained, most of which presented high yields and purity (all over 90%). The HSCCC method followed with preparative-HPLC appeared to be convenient and economical, constituting an efficient strategy for the isolation of grape skin polyphenols. PMID:27374588

  4. Velocity and pressure distribution behind bodies in an air current

    NASA Technical Reports Server (NTRS)

    Betz, A

    1924-01-01

    The following experiments on the air flow behind bodies were made for the purpose of assisting in the explanation of the phenomena connected with air resistance. The first two series of experiments dealt with the phenomena behind a cylinder. The third series of experiments was carried out behind a streamlined strut.

  5. Separation of two major chalcones from Angelica keiskei by high-speed counter-current chromatography.

    PubMed

    Kil, Yun-Seo; Nam, Joo-Won; Lee, Jun; Seo, Eun Kyoung

    2015-08-01

    Angelica keiskei (Shin-sun cho) is an edible higher plant with the beneficial preventive effects on cancer, hypertension, and coronary heart disease. Two bioactive chalcones of Shin-sun cho, xanthoangelol (1) and 4-hydroxyderricin (2), were separated simultaneously by using high-speed counter-current chromatography with a two-phase solvent system composed of n-hexane-EtOAc-MeOH-H2O (9:5:9:4). Only nonconsuming processes, solvent fractionations and Sephadex LH-20 column chromatography, were conducted as presteps. Xanthoangelol (1, 35.9 mg, 99.9 % purity at 254 and 365 nm) and 4-hydroxyderricin (2, 4.4 mg, 98.7 % purity at 254 nm and 98.8 % purity at 365 nm) were successfully purified from 70 mg of the processed extract from A. keiskei. The structures of two compounds were confirmed by (1)H- and (13)C-NMR analysis.

  6. Development of a Variable-Speed Residential Air-Source Integrated Heat Pump

    SciTech Connect

    Rice, C Keith; Shen, Bo; Munk, Jeffrey D; Ally, Moonis Raza; Baxter, Van D

    2014-01-01

    A residential air-source integrated heat pump (AS-IHP) is under development in partnership with a U.S. manufacturer. A nominal 10.6 kW (3-ton) cooling capacity variable-speed unit, the system provides both space conditioning and water heating. This multi-functional unit can provide domestic water heating (DWH) in either full condensing (FC) (dedicated water heating or simultaneous space cooling and water heating) or desuperheating (DS) operation modes. Laboratory test data were used to calibrate a vapor-compression simulation model for each mode of operation. The model was used to optimize the internal control options for efficiency while maintaining acceptable comfort conditions and refrigerant-side pressures and temperatures within allowable operating envelopes. Annual simulations were performed with the AS-IHP installed in a well-insulated house in five U.S. climate zones. The AS-IHP is predicted to use 45 to 60% less energy than a DOE minimum efficiency baseline system while meeting total annual space conditioning and water heating loads. Water heating energy use is lowered by 60 to 75% in cold to warmer climates, respectively. Plans are to field test the unit in Knoxville, TN.

  7. Statistical Short-Range Guidance for Peak Wind Speed Forecasts at Edwards Air Force Base, CA

    NASA Technical Reports Server (NTRS)

    Dreher, Joseph G.; Crawford, Winifred; Lafosse, Richard; Hoeth, Brian; Burns, Kerry

    2009-01-01

    The peak winds near the surface are an important forecast element for space shuttle landings. As defined in the Flight Rules (FR), there are peak wind thresholds that cannot be exceeded in order to ensure the safety of the shuttle during landing operations. The National Weather Service Spaceflight Meteorology Group (SMG) is responsible for weather forecasts for all shuttle landings, and is required to issue surface average and 10-minute peak wind speed forecasts. They indicate peak winds are a challenging parameter to forecast. To alleviate the difficulty in making such wind forecasts, the Applied Meteorology Unit (AMU) developed a PC-based graphical user interface (GUI) for displaying peak wind climatology and probabilities of exceeding peak wind thresholds for the Shuttle Landing Facility (SLF) at Kennedy Space Center (KSC; Lambert 2003). However, the shuttle occasionally may land at Edwards Air Force Base (EAFB) in southern California when weather conditions at KSC in Florida are not acceptable, so SMG forecasters requested a similar tool be developed for EAFB.

  8. A uniform laminar air plasma plume with large volume excited by an alternating current voltage

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Bao, Wenting; Chu, Jingdi; Zhang, Panpan; Jia, Pengying

    2015-12-01

    Using a plasma jet composed of two needle electrodes, a laminar plasma plume with large volume is generated in air through an alternating current voltage excitation. Based on high-speed photography, a train of filaments is observed to propagate periodically away from their birth place along the gas flow. The laminar plume is in fact a temporal superposition of the arched filament train. The filament consists of a negative glow near the real time cathode, a positive column near the real time anode, and a Faraday dark space between them. It has been found that the propagation velocity of the filament increases with increasing the gas flow rate. Furthermore, the filament lifetime tends to follow a normal distribution (Gaussian distribution). The most probable lifetime decreases with increasing the gas flow rate or decreasing the averaged peak voltage. Results also indicate that the real time peak current decreases and the real time peak voltage increases with the propagation of the filament along the gas flow. The voltage-current curve indicates that, in every discharge cycle, the filament evolves from a Townsend discharge to a glow one and then the discharge quenches. Characteristic regions including a negative glow, a Faraday dark space, and a positive column can be discerned from the discharge filament. Furthermore, the plasma parameters such as the electron density, the vibrational temperature and the gas temperature are investigated based on the optical spectrum emitted from the laminar plume.

  9. Current LTA technology developments. [Lighter-Than-Air aircraft

    NASA Technical Reports Server (NTRS)

    Mayer, N. J.

    1981-01-01

    Lighter-than-air aircraft (LTA) developments and research in the United States and other countries are reviewed. The emphasis in the U.S. is on VTOL airships capable of heavy lift, and on long endurance types for coastal maritime patrol. Design concepts include hybrids which combine heavier-than-air and LTA components and characteristics. Research programs are concentrated on aerodynamics, flight dynamics, and control of hybrid types.

  10. Current developments lighter than air systems. [heavy lift airships

    NASA Technical Reports Server (NTRS)

    Mayer, N. J.

    1981-01-01

    Lighter than air aircraft (LTA) developments and research in the United States and other countries are reviewed. The emphasis in the U.S. is on VTOL airships capable of heavy lift, and on long endurance types for coastal maritime patrol. Design concepts include hybrids which combine heavier than air and LTA components and characteristics. Research programs are concentrated on aerodynamics, flight dynamics, and control of hybrid types.

  11. The influence of current speed and vegetation density on flow structure in two macrotidal eelgrass canopies

    USGS Publications Warehouse

    Lacy, Jessica R.; Wyllie-Echeverria, Sandy

    2011-01-01

    The influence of eelgrass (Zostera marina) on near-bed currents, turbulence, and drag was investigated at three sites in two eelgrass canopies of differing density and at one unvegetated site in the San Juan archipelago of Puget Sound, Washington, USA. Eelgrass blade length exceeded 1 m. Velocity profiles up to 1.5 m above the sea floor were collected over a spring-neap tidal cycle with a downward-looking pulse-coherent acoustic Doppler profiler above the canopies and two acoustic Doppler velocimeters within the canopies. The eelgrass attenuated currents by a minimum of 40%, and by more than 70% at the most densely vegetated site. Attenuation decreased with increasing current speed. The data were compared to the shear-layer model of vegetated flows and the displaced logarithmic model. Velocity profiles outside the meadows were logarithmic. Within the canopies, most profiles were consistent with the shear-layer model, with a logarithmic layer above the canopy. However, at the less-dense sites, when currents were strong, shear at the sea floor and above the canopy was significant relative to shear at the top of the canopy, and the velocity profiles more closely resembled those in a rough-wall boundary layer. Turbulence was strong at the canopy top and decreased with height. Friction velocity at the canopy top was 1.5–2 times greater than at the unvegetated, sandy site. The coefficient of drag CD on the overlying flow derived from the logarithmic velocity profile above the canopy, was 3–8 times greater than at the unvegetated site (0.01–0.023 vs. 2.9 × 10−3).

  12. Chiral High-Speed Counter-Current Chromatography: Future Strategies for Chiral Selector Development.

    PubMed

    Ma, Ying; Ito, Yoichiro

    2014-01-01

    In conventional high-performance liquid chromatography, chiral separations are performed by chiral column with a chiral selector (CS) chemically boned to the solid support. In contrast, high-speed counter-current chromatography (HSCCC) performs chiral separations by dissolving CS in the liquid stationary phase. During the past two decades, several CSs were developed to successfully carry out chiral HSCCC which include N-dodecanoyl-L-proline-3,5-dimethylanilide, β-cyclodextrin derivatives, vancomycin, cinchona alkaloid derivatives, cellulose and amylose derivatives, tartaric acid derivatives, etc. Compared to HPLC which uses over hundred different kinds of CSs, the number of CSs effectively used in HSCCC is limited to several compounds. This may be due to the violent molecular movement of CS dissolved in the liquid stationary phase which reduces chiral selectivity based on steric affinity. Future development strategy of CS for HSCC proposed here is to suppress the molecular movement of the CS in the liquid stationary phase by the following three ways: 1) using viscous stationary phase such as aqueous-aqueous polymer phase system; 2) attaching a long hydrophobic chain to the asymmetric carbon, or 3) chemically bonding CS onto hydrophobic small particles such as carbon nanotubes, gold colloidal particles, and submicron silica particles.

  13. Chiral High-Speed Counter-Current Chromatography: Future Strategies for Chiral Selector Development

    PubMed Central

    Ma, Ying; Ito, Yoichiro

    2014-01-01

    In conventional high-performance liquid chromatography, chiral separations are performed by chiral column with a chiral selector (CS) chemically boned to the solid support. In contrast, high-speed counter-current chromatography (HSCCC) performs chiral separations by dissolving CS in the liquid stationary phase. During the past two decades, several CSs were developed to successfully carry out chiral HSCCC which include N-dodecanoyl-L-proline-3,5-dimethylanilide, β-cyclodextrin derivatives, vancomycin, cinchona alkaloid derivatives, cellulose and amylose derivatives, tartaric acid derivatives, etc. Compared to HPLC which uses over hundred different kinds of CSs, the number of CSs effectively used in HSCCC is limited to several compounds. This may be due to the violent molecular movement of CS dissolved in the liquid stationary phase which reduces chiral selectivity based on steric affinity. Future development strategy of CS for HSCC proposed here is to suppress the molecular movement of the CS in the liquid stationary phase by the following three ways: 1) using viscous stationary phase such as aqueous-aqueous polymer phase system; 2) attaching a long hydrophobic chain to the asymmetric carbon, or 3) chemically bonding CS onto hydrophobic small particles such as carbon nanotubes, gold colloidal particles, and submicron silica particles. PMID:24611132

  14. Optical Measurement of the Speed of Sound in Air Over the Temperature Range 300-650 K

    NASA Technical Reports Server (NTRS)

    Hart, Roger C.; Balla, R. Jeffrey; Herring, G. C.

    2000-01-01

    Using laser-induced thermal acoustics (LITA), the speed of sound in room air (1 atm) is measured over the temperature range 300-650 K. Since the LITA apparatus maintains a fixed sound wavelength as temperature is varied, this temperature range simultaneously corresponds to a sound frequency range of 10-15 MHz. The data are compared to a published model and typically agree within 0.1%-0.4% at each of 21 temperatures.

  15. Air pollution impacts of speed limitation measures in large cities: The need for improving traffic data in a metropolitan area

    NASA Astrophysics Data System (ADS)

    Baldasano, José M.; Gonçalves, María; Soret, Albert; Jiménez-Guerrero, Pedro

    2010-08-01

    Assessing the effects of air quality management strategies in urban areas is a major concern worldwide because of the large impacts on health caused by the exposure to air pollution. In this sense, this work analyses the changes in urban air quality due to the introduction of a maximum speed limit to 80 km h -1 on motorways in a large city by using a novel methodology combining traffic assimilation data and modelling systems implemented in a supercomputing facility. Albeit the methodology has been non-specifically developed and can be extrapolated to any large city or megacity, the case study of Barcelona is presented here. Hourly simulations take into account the entire year 2008 (when the 80 km h -1 limit has been introduced) vs. the traffic conditions for the year 2007. The data has been assimilated in an emission model, which considers hourly variable speeds and hourly traffic intensity in the affected area, taken from long-term measurement campaigns for the aforementioned years; it also permits to take into account the traffic congestion effect. Overall, the emissions are reduced up to 4%; however the local effects of this reduction achieve an important impact for the adjacent area to the roadways, reaching 11%. In this sense, the speed limitation effects assessed represent enhancements in air quality levels (5-7%) of primary pollutants over the area, directly improving the welfare of 1.35 million inhabitants (over 41% of the population of the Metropolitan Area) and affecting 3.29 million dwellers who are potentially benefited from this strategy for air quality management (reducing 0.6% the mortality rates in the area).

  16. High wind speed measurements of dimethylsulfide air/sea gas transfer by eddy correlation in the North Atlantic

    NASA Astrophysics Data System (ADS)

    Bell, T. G.; De Bruyn, W. J.; Miller, S. D.; Saltzman, E. S.; Slawksy, L.; Stacy, B.; Callaghan, A. H.

    2012-12-01

    Air/sea dimethylsulphide (DMS) fluxes and gas transfer coefficients (kDMS) were measured by eddy correlation over the western North Atlantic Ocean during June/July 2011 aboard the R/V Knorr. Atmospheric and seawater DMS were measured using atmospheric pressure chemical ionization mass spectrometry (API-CIMS). Seawater DMS was measured continuously from the ship's underway system using a porous membrane equilibrator and API-CIMS. The cruise included regions of high biological productivity, wind speeds from 0-18 m/sec and whitecap areas of 0-5%. Four stations were occupied during the cruise for periods of 24-36 hours. In general, the stations exhibited a linear relationship between kDMS and wind speed, although there were significant variations in the slope of this relationship. One of the stations showed kDMS increasing with wind speed to 10 m/sec and then levelling off at higher wind speeds. The data from this cruise suggest that gas transfer can vary substantially due to parameters other than wind speed, most likely sea state and surfactants.

  17. Simulation of effects of direction and air flow speed on temperature distribution in the room covered by various roof materials

    NASA Astrophysics Data System (ADS)

    Sukanto, H.; Budiana, E. P.; Putra, B. H. H.

    2016-03-01

    The objective of this research is to get a comparison of the distribution of the room temperature by using three materials, namely plastic-rubber composite, clay, and asbestos. The simulation used Ansys Fluent to get the temperature distribution. There were two conditions in this simulations, first the air passing beside the room and second the air passing in front of the room. Each condition will be varied with the air speed of 1 m/s, 2 m/s, 3 m/s, 4 m/s, 5 m/s for each material used. There are three heat transfers in this simulation, namely radiation, convection, and conduction. Based on the ANSI/ ASHRAE Standard 55-2004, the results of the simulation showed that the best temperature distribution was the roof of plastic-rubber composites.

  18. Measurement of direct current electric fields and plasma flow speeds in Jupiter's magnetosphere

    NASA Technical Reports Server (NTRS)

    Kellogg, Paul J.; Goetz, K.; Howard, R. L.; Monson, S. J.; Balogh, A.; Forsyth, R. J.

    1993-01-01

    During the encounter of Ulysses with Jupiter, we have measured two components of the dc electric field and deduced from them the flow speed in the Io toms, as well as the presence of a polar cap region end what we interpret as a cleft region. Within the toms the flow speed is approximately equal to the speed of a plasma corotating with Jupiter but has significant deviations. The dominant deviations have an apparent period of the order of Jupiter's rotation period, but this might be a latitudinal effect. Other important periods are about 40 min and less than 25 min.

  19. Cargo Logistics Airlift Systems Study (CLASS). Volume 1: Analysis of current air cargo system

    NASA Technical Reports Server (NTRS)

    Burby, R. J.; Kuhlman, W. H.

    1978-01-01

    The material presented in this volume is classified into the following sections; (1) analysis of current routes; (2) air eligibility criteria; (3) current direct support infrastructure; (4) comparative mode analysis; (5) political and economic factors; and (6) future potential market areas. An effort was made to keep the observations and findings relating to the current systems as objective as possible in order not to bias the analysis of future air cargo operations reported in Volume 3 of the CLASS final report.

  20. Apparatus and method for generating large mass flow of high temperature air at hypersonic speeds

    NASA Technical Reports Server (NTRS)

    Sabol, A. P.; Stewart, R. B. (Inventor)

    1973-01-01

    High temperature, high mass air flow and a high Reynolds number test air flow in the Mach number 8-10 regime of adequate test flow duration is attained by pressurizing a ceramic-lined storage tank with air to a pressure of about 100 to 200 atmospheres. The air is heated to temperatures of 7,000 to 8,000 R prior to introduction into the tank by passing the air over an electric arc heater means. The air cools to 5,500 to 6,000 R while in the tank. A decomposable gas such as nitrous oxide or a combustible gas such as propane is injected into the tank after pressurization and the heated pressurized air in the tank is rapidly released through a Mach number 8-10 nozzle. The injected gas medium upon contact with the heated pressurized air effects an exothermic reaction which maintains the pressure and temperature of the pressurized air during the rapid release.

  1. Influence of channel base current and varying return stroke speed on the calculated fields of three important return stroke models

    NASA Technical Reports Server (NTRS)

    Thottappillil, Rajeev; Uman, Martin A.; Diendorfer, Gerhard

    1991-01-01

    Compared here are the calculated fields of the Traveling Current Source (TCS), Modified Transmission Line (MTL), and the Diendorfer-Uman (DU) models with a channel base current assumed in Nucci et al. on the one hand and with the channel base current assumed in Diendorfer and Uman on the other hand. The characteristics of the field wave shapes are shown to be very sensitive to the channel base current, especially the field zero crossing at 100 km for the TCS and DU models, and the magnetic hump after the initial peak at close range for the TCS models. Also, the DU model is theoretically extended to include any arbitrarily varying return stroke speed with height. A brief discussion is presented on the effects of an exponentially decreasing speed with height on the calculated fields for the TCS, MTL, and DU models.

  2. Unmanned air vehicle flow separation control using dielectric barrier discharge plasma at high wind speed

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Huang, Yong; Wang, WanBo; Wang, XunNian; Li, HuaXing

    2014-06-01

    The present paper described an experimental investigation of separation control of an Unmanned Aerial Vehicle (UAV) at high wind speeds. The plasma actuator was based on Dielectric Barrier Discharge (DBD) and operated in a steady manner. The flow over a wing of UAV was performed with smoke flow visualization in the ϕ0.75 m low speed wind tunnel to reveal the flow structure over the wing so that the locations of plasma actuators could be optimized. A full model of the UAV was experimentally investigated in the ϕ3.2 m low speed wind tunnel using a six-component internal strain gauge balance. The effects of the key parameters, including the locations of the plasma actuators, the applied voltage amplitude and the operating frequency, were obtained. The whole test model was made of aluminium and acted as a cathode of the actuator. The results showed that the plasma acting on the surface of UAV could obviously suppress the boundary layer separation and reduce the model vibration at the high wind speeds. It was found that the maximum lift coefficient of the UAV was increased by 2.5% and the lift/drag ratio was increased by about 80% at the wind speed of 100 m/s. The control mechanism of the plasma actuator at the test configuration was also analyzed.

  3. California current eddy formation: ship, air, and satellite results.

    PubMed

    Bernstein, R L; Breaker, L; Whritner, R

    1977-01-28

    Until recently, quantitative measurements of the circulation of the California Current were limited to hydrographic determinations [See figure in the PDF file] of temperature and salinity. This information is now being augmented by satellite data. Clouds permitting, satellite scanner systems can locate major ocean frontal boundaries if they are associated with even quite weak horizontal sea-surface temperature gradients. The satellite data are most usefully interpreted in a region such as that encompassing the California Current, where the surface and main thermocline temperature distributions bear some relation to each other. In such a region, it is possible to make interpretations of circulation based on satellite-derived sea-surface temperature patterns. The correctness of these interpretations depends heavily on the availability of historical and present-day subsurface data, collected by conventional methods from ships and aircraft. Satellite infrared scanners, in addition to providing information on circulation with vastly increased spatial resolution, have the potential (with cooperative weather) for providing increased time resolution. These improvements in resolution have permitted us to see that much of the spatial variation in the California Current takes place along welldefined fronts and to observe the evolution of one particular meander.

  4. Assessment of corneal dynamics with high-speed swept source Optical Coherence Tomography combined with an air puff system

    NASA Astrophysics Data System (ADS)

    Alonso-Caneiro, David; Karnowski, Karol; Kaluzny, Bartlomiej J.; Kowalczyk, Andrzej; Wojtkowski, Maciej

    2011-07-01

    We present a novel method and instrument for in vivo imaging and measurement of the human corneal dynamics during an air puff. The instrument is based on high-speed swept source optical coherence tomography (ssOCT) combined with a custom adapted air puff chamber from a non-contact tonometer, which uses an air stream to deform the cornea in a non-invasive manner. During the short period of time that the deformation takes place, the ssOCT acquires multiple A-scans in time (M-scan) at the center of the air puff, allowing observation of the dynamics of the anterior and posterior corneal surfaces as well as the anterior lens surface. The dynamics of the measurement are driven by the biomechanical properties of the human eye as well as its intraocular pressure. Thus, the analysis of the M-scan may provide useful information about the biomechanical behavior of the anterior segment during the applanation caused by the air puff. An initial set of controlled clinical experiments are shown to comprehend the performance of the instrument and its potential applicability to further understand the eye biomechanics and intraocular pressure measurements. Limitations and possibilities of the new apparatus are discussed.

  5. Assessment of corneal dynamics with high-speed swept source optical coherence tomography combined with an air puff system.

    PubMed

    Alonso-Caneiro, David; Karnowski, Karol; Kaluzny, Bartlomiej J; Kowalczyk, Andrzej; Wojtkowski, Maciej

    2011-07-18

    We present a novel method and instrument for in vivo imaging and measurement of the human corneal dynamics during an air puff. The instrument is based on high-speed swept source optical coherence tomography (ssOCT) combined with a custom adapted air puff chamber from a non-contact tonometer, which uses an air stream to deform the cornea in a non-invasive manner. During the short period of time that the deformation takes place, the ssOCT acquires multiple A-scans in time (M-scan) at the center of the air puff, allowing observation of the dynamics of the anterior and posterior corneal surfaces as well as the anterior lens surface. The dynamics of the measurement are driven by the biomechanical properties of the human eye as well as its intraocular pressure. Thus, the analysis of the M-scan may provide useful information about the biomechanical behavior of the anterior segment during the applanation caused by the air puff. An initial set of controlled clinical experiments are shown to comprehend the performance of the instrument and its potential applicability to further understand the eye biomechanics and intraocular pressure measurements. Limitations and possibilities of the new apparatus are discussed.

  6. Determination, correlation, and mechanistic interpretation of effects of hydrogen addition on laminar flame speeds of hydrocarbon–air mixtures

    SciTech Connect

    Tang, C. L.; Huang, Z. H.; Law, C. K.

    2010-08-30

    The stretch-affected propagation speeds of expanding spherical flames of n-butane–air mixtures with hydrogen addition were measured at atmospheric pressure and subsequently processed through a nonlinear regression analysis to yield the stretch-free laminar flame speeds. Based on a hydrogen addition parameter (RH) and an effective fuel equivalence ratio (ΦF), these laminar flame speeds were found to increase almost linearly with RH, for ΦF between 0.6 and 1.4 and RHRH from 0 to 0.5, with the slope of the variation assuming a minimum around stoichiometry. These experimental results also agree well with computed values using a detailed reaction mechanism. Furthermore, a mechanistic investigation aided by sensitivity analysis identified that kinetic effects through the global activation energy, followed by thermal effects through the adiabatic flame temperature, have the most influence on the increase in the flame speeds and the associated linear variation with RH due to hydrogen addition. Nonequidiffusion effects due to the high mobility of hydrogen, through the global Lewis number, have the least influence. Further calculations for methane, ethene, and propane as the fuel showed similar behavior, leading to possible generalization of the phenomena and correlation.

  7. BOUNDARY-LAYER SIMILAR SOLUTIONS FOR EQUILIBRIUM DISSOCIATED AIR AND APPLICATION TO THE CALCULATION OF LAMINAR HEATTRANSFER DISTRIBUTION ON BLUNT BODIES IN HIGH-SPEED FLOW

    NASA Technical Reports Server (NTRS)

    Beckwith, I. E.; Cohen, N. B.

    1963-01-01

    Flat plate and stagnation flow heat transfer coefficients, similarity solutions of the laminar boundary layer for air in dissociation equilibrium and calculation of laminar heat-transfer distribution on blunt three-dimensional bodies in high speed flow

  8. Exploring Faraday's Law of Electrolysis Using Zinc-Air Batteries with Current Regulative Diodes

    ERIC Educational Resources Information Center

    Kamata, Masahiro; Paku, Miei

    2007-01-01

    Current regulative diodes (CRDs) are applied to develop new educational experiments on Faraday's law by using a zinc-air battery (PR2330) and a resistor to discharge it. The results concluded that the combination of zinc-air batteries and the CRD array is simpler, less expensive, and quantitative and gives accurate data.

  9. The Relation Between Wind Speed and Air-Sea Temperature Difference in the Marine Atmospheric Boundary Layer off Northwest Europe

    NASA Astrophysics Data System (ADS)

    Kettle, A. J.

    2014-12-01

    Wind speed and atmospheric stability have an important role in determining the turbulence in the marine atmospheric boundary layer (MABL) as well as the surface wave field. The understanding of MABL dynamics in northwest Europe is complicated by fetch effects, the proximity of coastlines, shallow topography, and larger scale circulation patterns (e.g., cold air outbreaks). Numerical models have difficulty simulating the marine atmospheric boundary layer in coastal areas and partially enclosed seas, and this is partly due to spatial resolution problems at coastlines. In these offshore environments, the boundary layer processes are often best understood directly from time series measurements from fixed platforms or buoys, in spite of potential difficulties from platform flow distortion as well as the spatial sparseness of the data sets. This contribution presents the results of time series measurements from offshore platforms in the North Sea and Norwegian Sea in terms of a summary diagnostic - wind speed versus air-sea temperature difference (U-ΔT) - with important implications for understanding atmospheric boundary layer processes. The U-ΔT diagram was introduced in earlier surveys of data from coastal (Sletringen; O.J. Andersen and J. Løvseth, J. Wind Eng. Ind. Aerodyn., 57, 97-109, 1995) and offshore (Statfjord A; K.J. Eidsvik, Boundary-Layer Meteorol., 32, 103-132, 1985) sites in northwest Europe to summarize boundary layer conditions at a given location. Additional information from a series of measurement purpose-built offshore measurement and oil/gas production platforms from the southern North Sea to the Norwegian Sea illustrates how the wind characteristics vary spatially over large distances, highlighting the influence of cold air outbreaks, in particular. The results are important for the offshore wind industry because of the way that wind turbines accrue fatigue damage in different conditions of atmospheric stability and wind speed.

  10. AIR QUALITY MODELING OF HAZARDOUS POLLUTANTS: CURRENT STATUS AND FUTURE DIRECTIONS

    EPA Science Inventory

    The paper presents a review of current air toxics modeling applications and discusses possible advanced approaches. Many applications require the ability to predict hot spots from industrial sources or large roadways that are needed for community health and Environmental Justice...

  11. Thermal analysis and temperature characteristics of a braking resistor for high-speed trains for changes in the braking current

    NASA Astrophysics Data System (ADS)

    Lee, Dae-Dong; Kang, Hyun-Il; Shim, Jae-Myung

    2015-09-01

    Electric brake systems are used in high-speed trains to brake trains by converting the kinetic energy of a railway vehicle to electric energy. The electric brake system consists of a regenerative braking system and a dynamic braking system. When the electric energy generated during the dynamic braking process is changed to heat through the braking resistor, the braking resistor can overheat; thus, failures can occur to the motor block. In this paper, a braking resistor for a high-speed train was used to perform thermal analyses and tests, and the results were analyzed. The analyzed data were used to estimate the dependence of the brake currents and the temperature rises on speed changes up to 300 km/h, at which a test could not be performed.

  12. Experimental and numerical study of the accuracy of flame-speed measurements for methane/air combustion in a slot burner

    SciTech Connect

    Selle, L.; Ferret, B.; Poinsot, T.

    2011-01-15

    Measuring the velocities of premixed laminar flames with precision remains a controversial issue in the combustion community. This paper studies the accuracy of such measurements in two-dimensional slot burners and shows that while methane/air flame speeds can be measured with reasonable accuracy, the method may lack precision for other mixtures such as hydrogen/air. Curvature at the flame tip, strain on the flame sides and local quenching at the flame base can modify local flame speeds and require corrections which are studied using two-dimensional DNS. Numerical simulations also provide stretch, displacement and consumption flame speeds along the flame front. For methane/air flames, DNS show that the local stretch remains small so that the local consumption speed is very close to the unstretched premixed flame speed. The only correction needed to correctly predict flame speeds in this case is due to the finite aspect ratio of the slot used to inject the premixed gases which induces a flow acceleration in the measurement region (this correction can be evaluated from velocity measurement in the slot section or from an analytical solution). The method is applied to methane/air flames with and without water addition and results are compared to experimental data found in the literature. The paper then discusses the limitations of the slot-burner method to measure flame speeds for other mixtures and shows that it is not well adapted to mixtures with a Lewis number far from unity, such as hydrogen/air flames. (author)

  13. [Air contamination in the Autonomous City of Buenos Aires: the current risk or future climate change, a false option].

    PubMed

    Abrutzky, Rosana; Dawidowski, Laura; Murgida, Ana; Natenzon, Claudia Eleonor

    2014-09-01

    Based on the theoretical framework of environmental risk, this article discusses the management of air quality in the Autonomous City of Buenos Aires in relation to current and potential impacts of toxic gases and global climate change on the health of the population. Information on historical and current management of the air was linked to the results of the South American Emissions, Megacities and Climate research project to assess danger, exposure, vulnerability and uncertainty as the dimensions of risk. By contextualizing public policies developed in recent decades on this subject, it was possible to identify emerging configurations of risk and uncertainties as accelerators of social vulnerability. On the one hand, the fact that there is a positive correlation between mortality, changes in temperature and air pollution was confirmed. On the other hand, it became clear that there is a disconnect between air quality management and health care management, while limitations were found in the proposed mitigation measures relating to emissions of greenhouse gases produced by fuel, revealing uncertainties regarding their efficacy.

  14. Cost characteristics of tilt-rotor, conventional air and high speed rail short-haul intercity passenger service

    NASA Technical Reports Server (NTRS)

    Schoendorfer, David L.; Morlok, Edward K.

    1985-01-01

    The cost analysis done to support an assessment of the potential for a small tilt-rotor aircraft to operate in short-haul intercity passenger service is described in detail. Anticipated costs of tilt-rotor air service were compared to the costs of two alternatives: conventional air and high speed rail (HSR). Costs were developed for corridor service, varying key market characteristics including distance, passenger volumes, and minimum frequency standards. The resulting cost vs output information can then be used to compare modal costs for essentially identical service quality and passenger volume or for different service levels and volumes for each mode, as appropriate. Extensive sensitivity analyses are performed. The cost-output features of these technologies are compared. Tilt-rotor is very attractive compared to HSR in terms of costs over the entire range of volume. It also has costs not dramatically different from conventional air, but tilt-rotor costs are generally higher. Thus some of its other advantages, such as the VTOL capability, must offset the cost disadvantage for it to be a preferred or competitive mode in any given market. These issues are addressed in the companion report which considers strategies for tilt-rotor development in commercial air service.

  15. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames

    DOE PAGES

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall onmore » the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.« less

  16. Response of flame thickness and propagation speed under intense turbulence in spatially developing lean premixed methane–air jet flames

    SciTech Connect

    Sankaran, Ramanan; Hawkes, Evatt R.; Yoo, Chun Sang; Chen, Jacqueline H.

    2015-06-22

    Direct numerical simulations of three-dimensional spatially-developing turbulent Bunsen flames were performed at three different turbulence intensities. We performed these simulations using a reduced methane–air chemical mechanism which was specifically tailored for the lean premixed conditions simulated here. A planar-jet turbulent Bunsen flame configuration was used in which turbulent preheated methane–air mixture at 0.7 equivalence ratio issued through a central jet and was surrounded by a hot laminar coflow of burned products. The turbulence characteristics at the jet inflow were selected such that combustion occured in the thin reaction zones (TRZ) regime. At the lowest turbulence intensity, the conditions fall on the boundary between the TRZ regime and the corrugated flamelet regime, and progressively moved further into the TRZ regime by increasing the turbulent intensity. The data from the three simulations was analyzed to understand the effect of turbulent stirring on the flame structure and thickness. Furthermore, statistical analysis of the data showed that the thermal preheat layer of the flame was thickened due to the action of turbulence, but the reaction zone was not significantly affected. A global and local analysis of the burning velocity of the flame was performed to compare the different flames. Detailed statistical averages of the flame speed were also obtained to study the spatial dependence of displacement speed and its correlation to strain rate and curvature.

  17. Walkie-Talkie Measurements for the Speed of Radio Waves in Air

    ERIC Educational Resources Information Center

    Dombi, Andra; Tunyagi, Arthur; Neda, Zoltan

    2013-01-01

    A handheld emitter-receiver device suitable for the direct estimation of the velocity of radio waves in air is presented. The velocity of radio waves is measured using the direct time-of-flight method, without the need for any tedious and precise settings. The results for two measurement series are reported. Both sets of results give an estimate…

  18. Pneumomediastinum secondary to use of a high speed air turbine drill during a dental extraction.

    PubMed Central

    Torres-Melero, J.; Arias-Diaz, J.; Balibrea, J. L.

    1996-01-01

    Pneumomediastinum and subcutaneous emphysema of the neck and thorax can occur exceptionally following a dental procedure. A case is described of acute subcutaneous emphysema of the lateral region of the neck and thorax associated with pneumomediastinum during a dental extraction with an air and water cooled turbine burn drill. PMID:8779147

  19. High-speed OH-PLIF imaging of deflagration-to-detonation transition in H2-air mixtures

    NASA Astrophysics Data System (ADS)

    Boeck, Lorenz R.; Mével, Rémy; Fiala, Thomas; Hasslberger, Josef; Sattelmayer, Thomas

    2016-06-01

    Planar laser-induced fluorescence (PLIF) is considered a standard experimental technique in combustion diagnostics. However, it has only been occasionally applied to explosion experiments with fast combustion regimes. It has been shown that single-shot OH-PLIF with high pulse energies yields clear fluorescence images of fast deflagrations and also detonations. This paper presents the first application of high-speed OH-PLIF at 20 kHz repetition rate to a deflagration-to-detonation transition experiment. Hydrogen-air mixtures at initial atmospheric pressure and ambient temperature are investigated. Satisfactory results are obtained for flame speeds up to about 500 m/s. Flame instabilities and turbulence-flame interactions are observed. Two factors limit the applicability of HS OH-PLIF toward higher flame speeds: excessive flame luminescence masking the HS OH-PLIF signal and strong absorption of laser light by the flame. The variation in OH-PLIF signal-to-background ratio across a DDT process is studied using a 1D laminar premixed flame simulation extended by spectroscopic models.

  20. Maglev vehicles and superconductor technology: Integration of high-speed ground transportation into the air travel system

    SciTech Connect

    Johnson, L.R.; Rote, D.M.; Hull, J.R.; Coffey, H.T.; Daley, J.G.; Giese, R.F.

    1989-04-01

    This study was undertaken to (1) evaluate the potential contribution of high-temperature superconductors (HTSCs) to the technical and economic feasibility of magnetically levitated (maglev) vehicles, (2) determine the status of maglev transportation research in the United States and abroad, (3) identify the likelihood of a significant transportation market for high-speed maglev vehicles, and (4) provide a preliminary assessment of the potential energy and economic benefits of maglev systems. HTSCs should be considered as an enhancing, rather than an enabling, development for maglev transportation because they should improve reliability and reduce energy and maintenance costs. Superconducting maglev transportation technologies were developed in the United States in the late 1960s and early 1970s. Federal support was withdrawn in 1975, but major maglev transportation programs were continued in Japan and West Germany, where full-scale prototypes now carry passengers at speeds of 250 mi/h in demonstration runs. Maglev systems are generally viewed as very-high-speed train systems, but this study shows that the potential market for maglev technology as a train system, e.g., from one downtown to another, is limited. Rather, aircraft and maglev vehicles should be seen as complementing rather than competing transportation systems. If maglev systems were integrated into major hub airport operations, they could become economical in many relatively high-density US corridors. Air traffic congestion and associated noise and pollutant emissions around airports would also be reduced. 68 refs., 26 figs., 16 tabs.

  1. Break-up and atomization of a round water jet by a high-speed annular air jet

    NASA Astrophysics Data System (ADS)

    Lasheras, J. C.; Villermaux, E.; Hopfinger, E. J.

    1998-02-01

    The near- and far-field break-up and atomization of a water jet by a high-speed annular air jet are examined by means of high-speed flow visualizations and phase Doppler particle sizing techniques. Visualization of the jet's near field and measurements of the frequencies associated with the gas liquid interfacial instabilities are used to study the underlying physical mechanisms involved in the primary break-up of the water jet. This process is shown to consist of the stripping of water sheets, or ligaments, which subsequently break into smaller lumps or drops. An entrainment model of the near-field stripping of the liquid is proposed, and shown to describe the measured liquid shedding frequencies. This simplified model explains qualitatively the dependence of the shedding frequency on the air/water momentum ratio in both initially laminar and turbulent water jets. The role of the secondary liquid break-up in the far-field atomization of the water jet is also investigated, and an attempt is made to apply the classical concepts of local isotropy to explain qualitatively the measurement of the far-field droplet size distribution and its dependence on the water to air mass and momentum ratios. Models accounting for the effect of the local turbulent dissipation rate in the gas on both the break-up and coalescence of the droplets are developed and compared with the measurements of the variation of the droplet size along the jet's centreline. The total flux of kinetic energy supplied by the gas per unit total mass of the spray jet was found to be the primary parameter determining the secondary break-up and coalescence of the droplets in the far field.

  2. The selection of convertible engines with current gas generator technology for high speed rotorcraft

    NASA Technical Reports Server (NTRS)

    Eisenberg, Joseph D.

    1990-01-01

    NASA-Lewis has sponsored two studies to determine the most promising convertible engine concepts for high speed rotorcraft. These studies projected year 2000 convertible technology limited to present gas generator technology. Propulsion systems for utilization on aircraft needing thrust only during cruise and those aircraft needing both power and thrust at cruise were investigated. Mission calculations for the two contractors involved were based upon the fold tilt rotor concept. Analysis and comparison of the General Electric concepts (geared UDF, clutched fan, and VIGV fan), and the Allison Gas Turbine concepts (clutched fan, VIGV fan, variable pitch fan, single rotation tractor propfan, and counter rotation tractor propfan) are presented.

  3. The selection of convertible engines with current gas generator technology for high speed rotorcraft

    NASA Technical Reports Server (NTRS)

    Eisenberg, Joseph D.

    1990-01-01

    NASA-Lewis sponsored two studies to determine the most promising convertible engine concepts for high speed rotorcraft. These studies projected year 2000 convertible technology limited to present gas generator technology. Propulsion systems for utilization on aircraft needing thrust only during cruise and those aircraft needing both power and thrust at cruise were investigated. Mission calculations for the two contractors involved were based upon the fold tilt rotor concept. Analysis and comparison of the General Electric concepts (geared UDF, clutched fan, and Variable Inlet Guide Vane (VIGV) fan), and the Allison Gas Turbine concepts (clutched fan, VIGV fan, variable pitch fan, single rotation tractor propfan, and counter rotation tractor propfan) are presented.

  4. The Measurement of Fluctuations of Air Speed by the Hot-Wire Anemometer

    NASA Technical Reports Server (NTRS)

    Dryden, H L; Kuethe, A M

    1930-01-01

    The hot-wire anemometer suggests itself as a promising method for measuring the fluctuating air velocities found in turbulent flow. The only obstacle is the presence of a lag due to the limited energy input which makes even a fairly small wire incapable of following rapid fluctuations with accuracy. This paper gives the theory of the lag and describes an experimental arrangement for compensating for the lag for frequencies up to 100 or more per second when the amplitude of the fluctuation is not too great. An experimental test of the accuracy of compensation and some results obtained with the apparatus in a wind-tunnel air stream are described. While the apparatus is very bulky in its present form, it is believed possible to develop a more portable arrangement. (author)

  5. Fiber optic sensors for measuring angular position and rotational speed. [air breathing engines

    NASA Technical Reports Server (NTRS)

    Baumbick, R. J.

    1980-01-01

    Two optical sensors, a 360 deg rotary encoder and a tachometer, were built for operation with the light source and detectors located remotely from the sensors. The source and detectors were coupled to the passive sensing heads through 3.65 meter fiber optic cables. The rotary encoder and tachometer were subjected to limited environmental testing. They were installed on an air breathing engine during recent altitude tests. Over 100 hours of engine operation were accumulated without any failure of either device.

  6. Displacement current induced by spin resonance in air-treated conjugated polymer diodes

    NASA Astrophysics Data System (ADS)

    Kanemoto, Katsuichi; Matsuoka, Hidenobu; Ueda, Yujiro; Takemoto, Keisuke; Kimura, Keiji; Hashimoto, Hideki

    2012-09-01

    We demonstrate that air-treated conjugated polymer diodes under photoexcitation give rise to a transient current exceeding a steady-state photocurrent by electron-spin resonance (ESR). The current induced by ESR is shown to exhibit a spiked time response for modulation of the resonance condition. The nature of the spike current is demonstrated to be a displacement current, which suggests that the spin transitions can change the film permittivity. This system has applications as devices enabling direct control of diode current by spin manipulation.

  7. Sleep Transistor Sizing According to Circuit Speed, Silicon Area and Leakage Current in High-Performance Digital Circuit Modules

    NASA Astrophysics Data System (ADS)

    Kucukkomurler, Ahmet; Garverick, Steven L.

    It is proposed that the power supply of key circuit modules could be gated to achieve significant reductions of leakage current, with minimal costs to circuit speed and die area in 0.25, 0.18 and 0.07 µm technologies. This study describes an extension to power supply gating using body overdrive and gate underdrive, analysis techniques to predict leakage current and performance parameters, a procedure for optimization of the sleep transistor size and simulation results that demonstrate the accuracy of the analysis and advantages of the approach. A leakage current estimation technique has been studied using the Berkeley Predictive Technology Model Parameters. An estimation technique has been verified using ISCAS85 combinational Benchmark test circuits. Finally the optimization algorithm has been verified using these same benchmark test circuits.

  8. High-speed measurement of an air transect's temperature shift heated by laser beam

    NASA Astrophysics Data System (ADS)

    Li, WenYu; Jiang, ZongFu; Xi, Fengjie; Li, Qiang; Xie, Wenke

    2005-02-01

    Laser beam heat the air on the optic path, Beam-deflection optical tomography is a non-intrusive method to measure the 2-dimension temperature distribution in the transect. By means of linear Hartmann Sensor at the rate of 27kHz, the optic path was heated by a 2.7μm HF laser, continuous and high time resolution gradients of optic phase were obtained. the result of analysing and calculation showed the temperament shift in the heated beam path was not higher than 50K when the HF laser power was 9W. The experiment showed that it is a practical non-intrusive temperature shift measurement method for a small area aero-optical medium.

  9. Transport, deposition, and liftoff in laboratory density currents composed of hot particles in air

    NASA Astrophysics Data System (ADS)

    Andrews, B. J.; Manga, M.

    2010-12-01

    Understanding the dynamics of transport, deposition, and air entrainment in pyroclastic density currents (PDCs) is required for accurate predictions of future current behaviors and interpretations of ancient deposits, but directly observing the interiors of natural PDCs is effectively impossible. We model PDCs with scaled, hot, particle-laden density currents generated in a 6 m long, 0.6 m wide, 1.8 m tall air-filled tank. Comparison of relevant scaling between our experiments and natural PDCs indicates that we are accurately capturing much of the dynamics of dilute PDCs: * Reynolds numbers of our experiments are lower than natural currents, 10^3 compared to 10^6, but still fully turbulent; * Densimetric and Thermal Richardson numbers are of O(1) in both natural and modeled currents; * Stokes and settling numbers for particles in the experiments fall within the expected range for natural PDCs. Conditions within the tank are monitored with temperature and humidity probes. Experiments are illuminated with sheet lighting, and recorded with high-definition video cameras. In general, currents have average velocities of 10-20 cm/s, initial thicknesses of 10-20 cm (although thickness greatly increases as currents entrain and expand air), and run out or lift off distances of 3-5 m. Large Kelvin-Helmholtz type eddies usually form along the top of the current immediately behind the head; these vortices are similar in size to the total current thickness. In currents that lift off, the distal current end typically retreats with time. Preliminary results suggest that lift off distance decreases with increasing thermal Richardson number. Analysis of turbulent structures indicates that the current heads are dominated by large coherent structures with length scales, L, comparable to the current thickness. Within 5-10 L of the current fronts, sequences of similar large eddies often occur. At greater distances behind the current fronts, turbulent structures become smaller and less

  10. Isolation and purification of ginkgo flavonol glycosides from Ginkgo biloba leaves by high-speed counter-current chromatography.

    PubMed

    Zhang, Qiang; Chen, Li-Juan; Ye, Hao-Yu; Gao, Lei; Hou, Wenli; Tang, Minghai; Yang, Guangli; Zhong, Zhenhua; Yuan, Yuan; Peng, Aihua

    2007-08-01

    A high-speed counter-current chromatography method was developed for the separation and purification of bioactive flavonol glycosides from a crude ethanol extract of Ginkgo biloba leaves. The separation was performed with a two-phase solvent system composed of n-hexane-butanol-ethyl acetate-methanol-0.5% acetic acid (1:0.5:3.5:1:4, v/v) and three pure compounds were eluted in high purities in a one-step separation. Their purities were determined by HPLC and identified by MS,(1)H-NMR, and(13)C-NMR.

  11. Advanced variable speed air source integrated heat pump (AS-IHP) development - CRADA final report

    SciTech Connect

    Baxter, Van D.; Rice, C. Keith; Munk, Jeffrey D.; Ally, Moonis Raza; Shen, Bo

    2015-09-30

    Between August 2011 and September 2015, Oak Ridge National Laboratory (ORNL) and Nordyne, LLC (now Nortek Global HVAC LLC, NGHVAC) engaged in a Cooperative Research and Development Agreement (CRADA) to develop an air-source integrated heat pump (AS-IHP) system for the US residential market. Two generations of laboratory prototype systems were designed, fabricated, and lab-tested during 2011-2013. Performance maps for the system were developed using the latest research version of the DOE/ORNL Heat Pump Design Model, or HPDM, (Rice 1991; Rice and Jackson 2005; Shen et al 2012) as calibrated against the lab test data. These maps were the input to the TRNSYS (SOLAR Energy Laboratory, et al, 2010) system to predict annual performance relative to a baseline suite of equipment meeting minimum efficiency standards in effect in 2006 (combination of 13 SEER air-source heat pump (ASHP) and resistance water heater with Energy Factor (EF) of 0.9). Predicted total annual energy savings, while providing space conditioning and water heating for a tight, well insulated 2600 ft2 (242 m2) house at 5 U.S. locations, ranged from 46 to 61%, averaging 52%, relative to the baseline system (lowest savings at the cold-climate Chicago location). Predicted energy use for water heating was reduced 62 to 76% relative to resistance WH. Based on these lab prototype test and analyses results a field test prototype was designed and fabricated by NGHVAC. The unit was installed in a 2400 ft2 (223 m2) research house in Knoxville, TN and field tested from May 2014 to April 2015. Based on the demonstrated field performance of the AS-IHP prototype and estimated performance of a baseline system operating under the same loads and weather conditions, it was estimated that the prototype would achieve ~40% energy savings relative to the minimum efficiency suite. The estimated WH savings were >60% and SC mode savings were >50%. But estimated SH savings were only about 20%. It is believed that had the test

  12. Review of current research and long-term research needs in air pollution

    SciTech Connect

    Stern, A.C.

    1985-01-01

    Current research and long-term research needs of air pollution are reviewed and assessed in the following areas: pollution definition and characterization; atmospheric chemistry; measurement and monitoring of ambient air and sources; effects of human health and welfare, vegetation, animals, aquatic life, materials and structures; air pollution meteorology and modeling; engineering control; and regulatory control. The work spans NSF program categories including atmospheric sciences, chemical and process engineering, chemistry, biotic systems, materials research, mechanical engineering, physics, physiology, research instrumentation, and economic sciences. An attempt is made to analyze these research areas to determine how the research could be made more useful and effective by merging and crossing disciplinary lines with interdisciplinary approaches. An appendix provides a detailed listing of air pollution research projects in progress during 1985.

  13. Review of current research and long-term research needs in air pollution

    SciTech Connect

    Stern, A.C.

    1985-01-01

    Current research and long-term research needs of air pollution are reviewed and assessed in the following areas: pollution definition and characterization; atmospheric chemistry; measurement and monitoring of ambient air and sources; effects of human health and welfare, vegetation, animals, aquatic life, materials and structures; air pollution meteorology and modeling; engineering control; and regulatory control. The work spans NSF program categories including atmospheric sciences, chemical and process engineering, chemistry, biotic systems, materials research, mechanical engineering, physics, physiology, research instrumentation, and economic sciences. An attempt is made to analyze these research areas to determine how the research could be made more useful and effective by merging and crossing disciplinary lines with inderdisciplinary approaches. An appendix provides a detailed listing of air pollution research projects in progress during 1985.

  14. Time-Resolved Optical Measurements of Fuel-Air Mixedness in Windowless High Speed Research Combustors

    NASA Technical Reports Server (NTRS)

    Nguyen, Quang-Viet

    1998-01-01

    Fuel distribution measurements in gas turbine combustors are needed from both pollution and fuel-efficiency standpoints. In addition to providing valuable data for performance testing and engine development, measurements of fuel distributions uniquely complement predictive numerical simulations. Although equally important as spatial distribution, the temporal distribution of the fuel is an often overlooked aspect of combustor design and development. This is due partly to the difficulties in applying time-resolved diagnostic techniques to the high-pressure, high-temperature environments inside gas turbine engines. Time-resolved measurements of the fuel-to-air ratio (F/A) can give researchers critical insights into combustor dynamics and acoustics. Beginning in early 1998, a windowless technique that uses fiber-optic, line-of-sight, infrared laser light absorption to measure the time-resolved fluctuations of the F/A (refs. 1 and 2) will be used within the premixer section of a lean-premixed, prevaporized (LPP) combustor in NASA Lewis Research Center's CE-5 facility. The fiber-optic F/A sensor will permit optical access while eliminating the need for film-cooled windows, which perturb the flow. More importantly, the real-time data from the fiber-optic F/A sensor will provide unique information for the active feedback control of combustor dynamics. This will be a prototype for an airborne sensor control system.

  15. The dynamics of the HSCT environment. [air pollution from High Speed Civil Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Douglass, Anne R.; Rood, Richard B.

    1991-01-01

    Assessments of the impact of aircraft engine exhausts on stratospheric ozone levels are currently limited to 2D zonally-averaged models which, while completely representing chemistry, involve high parameterization of transport processes. Prospective 3D models under development by NASA-Goddard will use winds from a data-assimilation procedure; the upper troposphere/lower stratosphere behavior of one such model has been verified by direct comparison of model simulations with satellite, balloon, and sonde measurements. Attention is presently given to the stratosphere/troposphere exchange and nonzonal distribution of aircraft engine exhaust.

  16. Are Current Law Enforcement Strategies Associated with a Lower Risk of Repeat Speeding Citations and Crash Involvement? A Longitudinal Study of Speeding Maryland Drivers

    PubMed Central

    Amr, Sania; Braver, Elisa R.; Langenberg, Patricia; Zhan, Min; Smith, Gordon S.; Dischinger, Patricia C.

    2013-01-01

    PURPOSE To determine whether traffic court appearances and different court verdicts were associated with risk of subsequent speeding citations and crashes. METHODS A cohort of 29,754 Maryland drivers ticketed for speeding who either went to court or paid fines by mail in May/June 2003 was followed for 3 years. Drivers appearing in court were categorized by verdicts: 1) not guilty, 2) suspension of prosecution/no prosecution (STET/NP), 3) case dismissed, 4) probation before judgment and fines (PBJ), or 5) fines and demerit points. Cox proportional hazard models were used to estimate adjusted hazard ratios (AHR). RESULTS Court appearances were associated with lower risk of subsequent speeding citations (AHR = 0.92; 95% CI: 0.88-0.96), but higher risk of crashes (AHR=1.25; 95% CI: 1.16-1.35). PBJ was associated with significantly lower repeat speeding tickets (AHR = 0.83; 95% CI = 0.75-0.91) and a non-significant decrease in crashes (AHR = 0.87; 95% CI 0.75-1.02). Both repeat speeding tickets and subsequent crashes were significantly lower in the STET/NP group. CONCLUSIONS PBJ and STET/NP may reduce speeding and crashes, but neither verdict eliminated excess crash risk among drivers who choose court appearances. Randomized controlled evaluations of speeding countermeasures are needed to inform traffic safety policies. PMID:21684176

  17. Preparative isolation and purification of xanthohumol from hops (Humulus lupulus L.) by high-speed counter-current chromatography.

    PubMed

    Chen, Qi-He; Fu, Ming-Liang; Chen, Miao-Miao; Liu, Jing; Liu, Xiao-Jie; He, Guo-Qing; Pu, Shou-Cheng

    2012-05-01

    Xanthohumol (XN) and related prenylflavonoids are the main bioactive components of hops (Humulus lupulus L.). The current work is to investigate the use of high-speed counter-current chromatography (HSCCC) in search for high isolation of xanthohumol from hops. A solvent system consisted of n-hexane-ethyl acetate-methanol-water at a volume ratio of 5:5:4:3 was employed. The results demonstrated that the constructed method could be well applied for the isolation of xanthohumol from hops extract. After HSCCC isolation procedure, the purity of xanthohumol was over 95% assayed by HPLC and the yield of extraction was 93.60%. The chemical structure identification of xanthohumol was carried out by UV, (1)H NMR and (13)C NMR. The present results demonstrated that xanthohumol could be efficiently obtained using a single HSCCC step from H. lupulus L. extract.

  18. Isolation and purification of arctigenin from Fructus Arctii by enzymatic hydrolysis combined with high-speed counter-current chromatography.

    PubMed

    Liu, Feng; Xi, Xingjun; Wang, Mei; Fan, Li; Geng, Yanling; Wang, Xiao

    2014-02-01

    Enzymatic hydrolysis pretreatment combined with high-speed counter-current chromatography for the transformation and isolation of arctigenin from Fructus Arctii was successfully developed. In the first step, the extract solution of Fructus Arctii was enzymatic hydrolyzed by β-glucosidase. The optimal hydrolysis conditions were 40°C, pH 5.0, 24 h of hydrolysis time, and 1.25 mg/mL β-glucosidase concentration. Under these conditions, the content of arctigenin was transformed from 2.60 to 12.59 mg/g. In the second step, arctigenin in the hydrolysis products was separated and purified by high-speed counter-current chromatography with a two-phase solvent system composed of petroleum ether/ethyl acetate/methanol/water (10:25:15:20, v/v), and the fraction was analyzed by HPLC, ESI-MS, and (1)H NMR spectroscopy. Finally, 102 mg of arctigenin with a purity of 98.9% was obtained in a one-step separation from 200 mg of hydrolyzed sample.

  19. Effects of water-current speed on hematological, biochemical and immune parameters in juvenile tinfoil barb, Barbonymus schwanenfeldii (Bleeker, 1854)

    NASA Astrophysics Data System (ADS)

    Zhu, Zhiming; Song, Bolan; Lin, Xiaotao; Xu, Zhongneng

    2016-01-01

    This study examines the effect of water-current speed on hematological, biochemical and immune parameters in juvenile tinfoil barb ( Barbonymus schwanenfeldii). Blood samples were taken on days 1, 23 and 45 from control fish and from two training groups maintained at current speeds of 0.06 bl/s (body length per second), 0.66 bl/s, and 1.92 bl/s, respectively. Significantly increased red-blood-cell counts and hematocrit were observed in the post-training groups on days 23 and 45. Significantly increased hemoglobin concentrations were also observed in the 1.92 bl/s group on days 23 and 45. In contrast, values of mean corpuscular volume were significantly lower in the 1.92 bl/s group than in the other groups on day 45. Nitroblue-tetrazolium-positive cells and lysozyme and superoxidase dismutase activities in the plasma increased significantly with increasing training intensity on days 23 and 45. Antibacterial activities were significantly increased in the trained groups compared with the control group on day 23; significantly elevated alkaline phosphatase activity was observed in the 1.92 bl/s groups on day 45. Therefore, training intensities of 0.66 and 1.92 bl/s enhanced the blood oxygen-carrying capability and plasma immune parameters of juvenile tinfoil barbs.

  20. Isolation and purification of arctigenin from Fructus Arctii by enzymatic hydrolysis combined with high-speed counter-current chromatography.

    PubMed

    Liu, Feng; Xi, Xingjun; Wang, Mei; Fan, Li; Geng, Yanling; Wang, Xiao

    2014-02-01

    Enzymatic hydrolysis pretreatment combined with high-speed counter-current chromatography for the transformation and isolation of arctigenin from Fructus Arctii was successfully developed. In the first step, the extract solution of Fructus Arctii was enzymatic hydrolyzed by β-glucosidase. The optimal hydrolysis conditions were 40°C, pH 5.0, 24 h of hydrolysis time, and 1.25 mg/mL β-glucosidase concentration. Under these conditions, the content of arctigenin was transformed from 2.60 to 12.59 mg/g. In the second step, arctigenin in the hydrolysis products was separated and purified by high-speed counter-current chromatography with a two-phase solvent system composed of petroleum ether/ethyl acetate/methanol/water (10:25:15:20, v/v), and the fraction was analyzed by HPLC, ESI-MS, and (1)H NMR spectroscopy. Finally, 102 mg of arctigenin with a purity of 98.9% was obtained in a one-step separation from 200 mg of hydrolyzed sample. PMID:24311558

  1. Preparative isolation and purification of antioxidative diarylheptanoid derivatives from Alnus japonica by high-speed counter-current chromatography.

    PubMed

    Lim, Soon Sung; Lee, Min Young; Ahn, Hong Ryul; Choi, Soon Jung; Lee, Jae-Yong; Jung, Sang Hoon

    2011-12-01

    This study employed the online HPLC-2,2'-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS)(+) bioassay to rapidly determine the antioxidant compounds occurring in the crude extract of Alnus japonica. The negative peaks of the ABTS(+) radical scavenging detection system, which indicated the presence of antioxidant activity, were monitored by measuring the decrease in absorbance at 734 nm. The ABTS(+)-based antioxidant activity profile showed that three negative peaks exhibited antioxidant activity. High-speed counter-current chromatography (HSCCC) was used for preparative scale separation of the three active peaks from the extract. The purity of the isolated compounds was analyzed by HPLC and their structures were identified by (1)H- and (13)C-nuclear magnetic resonance spectrometry (NMR), heteronuclear multiple bond correlation (HMBC), and heteronuclear single quantum correlation (HSQC). Two solvent systems composed of n-hexane/ethylacetate/methanol/water (4:6:4:6, v/v) and of ethyl acetate/methanol/water (1:0.1:1, v/v) were performed in high-speed counter-current chromatography. Consequently, a total of 527 mg of hirsutanonol 5-O-β-D-glucopyranoside, 80.04 mg of 3-deoxohirsutenonol 5-O-β-D-glucopyranoside, and 91.0 mg of hirsutenone were obtained with purity of 94.7, 90.5, and 98.6%, respectively.

  2. Air

    MedlinePlus

    ... do to protect yourself from dirty air . Indoor air pollution and outdoor air pollution Air can be polluted indoors and it can ... this chart to see what things cause indoor air pollution and what things cause outdoor air pollution! Indoor ...

  3. Aircraft Speed Instruments

    NASA Technical Reports Server (NTRS)

    Beij, K Hilding

    1933-01-01

    This report presents a concise survey of the measurement of air speed and ground speed on board aircraft. Special attention is paid to the pitot-static air-speed meter which is the standard in the United States for airplanes. Air-speed meters of the rotating vane type are also discussed in considerable detail on account of their value as flight test instruments and as service instruments for airships. Methods of ground-speed measurement are treated briefly, with reference to the more important instruments. A bibliography on air-speed measurement concludes the report.

  4. Regulation of stroke pattern and swim speed across a range of current velocities: diving by common eiders wintering in polynyas in the Canadian Arctic.

    PubMed

    Heath, Joel P; Gilchrist, H Grant; Ydenberg, Ronald C

    2006-10-01

    Swim speed during diving has important energetic consequences. Not only do costs increase as drag rises non-linearly with increasing speed, but speed also affects travel time to foraging patches and therefore time and energy budgets over the entire dive cycle. However, diving behaviour has rarely been considered in relation to current velocity. Strong tidal currents around the Belcher Islands, Nunavut, Canada, produce polynyas, persistent areas of open water in the sea ice which are important habitats for wildlife wintering in Hudson Bay. Some populations of common eiders Somateria mollissima sedentaria remain in polynyas through the winter where they dive to forage on benthic invertebrates. Strong tidal currents keep polynyas from freezing, but current velocity can exceed 1.5 m s(-1) and could influence time and energy costs of diving and foraging. Polynyas therefore provide naturally occurring flume tanks allowing investigation of diving strategies of free ranging birds in relation to current velocity. We used a custom designed sub-sea ice camera to non-invasively investigate over 150 dives to a depth of 11.3 m by a population of approximately 100 common eiders at Ulutsatuq polynya during February and March of 2002 and 2003. Current speed during recorded dives ranged from 0 to 1 m s(-1). As currents increased, vertical descent speed of eiders decreased, while descent duration and the number of wing strokes and foot strokes during descent to the bottom increased. However, nearly simultaneous strokes of wings and feet, and swim speed relative to the moving water, were maintained within a narrow range (2.28+/-0.23 Hz; 1.25+/-0.14 m s(-1), respectively). This close regulation of swim speed over a range in current speed of 1.0 m s(-1) might correspond to efficient muscle contraction rates, and probably reduces work rates by avoiding rapidly increasing drag at greater speeds; however, it also increases travel time to benthic foraging patches. Despite regulation of

  5. Current-voltage characteristics of dc corona discharges in air between coaxial cylinders

    SciTech Connect

    Zheng, Yuesheng; Zhang, Bo He, Jinliang

    2015-02-15

    This paper presents the experimental measurement and numerical analysis of the current-voltage characteristics of dc corona discharges in air between coaxial cylinders. The current-voltage characteristics for both positive and negative corona discharges were measured within a specially designed corona cage. Then the measured results were fitted by different empirical formulae and analyzed by the fluid model. The current-voltage characteristics between coaxial cylinders can be expressed as I = C(U − U{sub 0}){sup m}, where m is within the range 1.5–2.0, which is similar to the point-plane electrode system. The ionization region has no significant effect on the current-voltage characteristic under a low corona current, while it will affect the distribution for the negative corona under a high corona current. The surface onset fields and ion mobilities were emphatically discussed.

  6. High speed on-chip current measurement using a low-Q tunable LC resonator

    NASA Astrophysics Data System (ADS)

    Campbell, Brooks; Chen, Z.; Chiaro, B.; Dunsworth, A.; Neill, C.; O'Malley, P. J. J.; Quintana, C.; Vainsencher, A.; Wenner, J.; Barends, R.; Chen, Y.; Fowler, A.; Jeffrey, E.; Kelly, J.; Lucero, E.; Megrant, A.; Mutus, J.; Neeley, M.; Roushan, P.; Sank, D.; White, T. C.; Martinis, John M.

    Superconducting quantum computing technology requires precise high frequency analog waveforms to perform single and multi-qubit gates. Due to signal path irregularities, gates are tuned-up by perturbing the drive signal until qubit state populations indicate the desired gate function. A more direct approach is to measure the effect of circuit imperfections by sampling control waveforms directly, as seen by the qubits. We proceed by measuring the resonant frequency shift of a capacitively shunted SQUID and converting the control waveform to DC flux applied to the SQUID. By measuring the reflected phase of a CW tone applied to this resonant circuit while applying the resonance-shifting flux pulse, we are able to reconstruct the current waveform of the input pulse at the SQUID loop. This device's geometry is the same as the z-control lines used in qubit experiments to control the qubit frequency. I will present this method of on-chip waveform sampling for superconducting circuits in addition to proof of concept data. This technique opens the door for improved gate bring up and a deeper understanding of qubit control as well as the circuit parasitics that deform these waveforms.

  7. Monopolar electromyographic signals recorded by a current amplifier in air and under water without insulation.

    PubMed

    Whitting, John W; von Tscharner, Vinzenz

    2014-12-01

    It was recently proposed that one could use signal current instead of voltage to collect surface electromyography (EMG). With EMG-current, the electrodes remain at the ground potential, thereby eliminating lateral currents. The purpose of this study was to determine whether EMG-currents can be recorded in Tap and Salt water, as well as in air, without electrically shielding the electrodes. It was hypothesized that signals would display consistent information between experimental conditions regarding muscle responses to changes in contraction effort. EMG-currents were recorded from the flexor digitorum muscles as participant's squeezed a pre-inflated blood pressure cuff bladder in each experimental condition at standardized efforts. EMG-current measurements performed underwater showed no loss of signal amplitude when compared to measurements made in air, although some differences in amplitude and spectral components were observed between conditions. However, signal amplitudes and frequencies displayed consistent behavior across contraction effort levels, irrespective of the experimental condition. This new method demonstrates that information regarding muscle activity is comparable between wet and dry conditions when using EMG-current. Considering the difficulties imposed by the need to waterproof traditional bipolar EMG electrodes when underwater, this new methodology is tremendously promising for assessments of muscular function in aquatic environments.

  8. Monopolar electromyographic signals recorded by a current amplifier in air and under water without insulation.

    PubMed

    Whitting, John W; von Tscharner, Vinzenz

    2014-12-01

    It was recently proposed that one could use signal current instead of voltage to collect surface electromyography (EMG). With EMG-current, the electrodes remain at the ground potential, thereby eliminating lateral currents. The purpose of this study was to determine whether EMG-currents can be recorded in Tap and Salt water, as well as in air, without electrically shielding the electrodes. It was hypothesized that signals would display consistent information between experimental conditions regarding muscle responses to changes in contraction effort. EMG-currents were recorded from the flexor digitorum muscles as participant's squeezed a pre-inflated blood pressure cuff bladder in each experimental condition at standardized efforts. EMG-current measurements performed underwater showed no loss of signal amplitude when compared to measurements made in air, although some differences in amplitude and spectral components were observed between conditions. However, signal amplitudes and frequencies displayed consistent behavior across contraction effort levels, irrespective of the experimental condition. This new method demonstrates that information regarding muscle activity is comparable between wet and dry conditions when using EMG-current. Considering the difficulties imposed by the need to waterproof traditional bipolar EMG electrodes when underwater, this new methodology is tremendously promising for assessments of muscular function in aquatic environments. PMID:25241214

  9. [Isolation and preparation of gallic acid from Terminalia chebula Retz. with high-speed counter-current chromatography].

    PubMed

    Li, Zhongqin; Li, Qiuyun; Jiang, Xinglong; Zhang, Kun; Guan, Ruizhang

    2014-12-01

    A separation method based on high-speed counter-current chromatography (HSCCC) has been established for the isolation and preparation of gallic acid from the ethanol extract of Terminalia chebula Retz. After comparing five kinds of solvent protocols of HSCCC, the two-phase system of n-hexane-ethyl acetate-methanol-water (1:5:1:5, v/v/v/v) was finally chosen as the operating solvent of HSCCC for the separation of gallic acid, in which the lower phase was used as the mobile phase and the upper phase as stationary phase. The detection in the experiments was performed with an ultraviolet detector at 254 nm. Under the conditions of rotation speed of 850 r/min, lower phase flow rate of 2 mL/min, four peaks (I/II/III/IV) were displayed on HSCCC chromatogram. Among them, only peak III contained a large amount of gallic acid (about 96. 40%), which was confirmed by electrospray ionization mass spectrometry (ESI-MS) and high performance liquid chromatographic (HPLC) analysis. As much as 8. 6 mg of gallic acid was obtained from 100 mg of the ethanol extract of Terminalia chebula Retz., indicating the method is simple, robust and efficient for the preparation of gallic acid.

  10. Isolation of cyanidin 3-glucoside from blue honeysuckle fruits by high-speed counter-current chromatography.

    PubMed

    Chen, Liang; Xin, Xiulan; Lan, Rong; Yuan, Qipeng; Wang, Xiaojie; Li, Ye

    2014-01-01

    Blue honeysuckle fruits are rich in anthocyanins with many beneficial effects such as reduction of the risk of cardiovascular diseases, diabetes and cancers. High-speed counter-current chromatography (HSCCC) was used for the separation of anthocyanin on a preparative scale from blue honeysuckle fruit crude extract with a biphasic solvent system composed of tert-butyl methyl ether/n-butanol/acetonitrile/water/trifluoroacetic acid (2:2:1:5:0.01, v/v) for the first time in this paper. Each injection of 100 mg crude extract yielded 22.8 mg of cyanidin 3-glucoside (C3G) at 98.1% purity. The compound was identified by means of electro-spray ionisation mass (ESI/MS) and (1)H and (13)C nuclear magnetic resonance (NMR) spectra.

  11. ISOLATION OF GLYCOSIDES FROM THE BARKS OF ILEX ROTUNDA BY HIGH-SPEED COUNTER-CURRENT CHROMATOGRAPHY

    PubMed Central

    Wang, Chun; Chao, Zhimao; Sun, Wen; Wu, Xiaoyi; Ito, Yoichiro

    2013-01-01

    Semi-preparative and preparative high-speed counter-current chromatography (HSCCC) were successfully used for isolation of glycosides from 50% ethanol extract of the dried barks of Ilex rotunda Thunb. (Aquifoliaceae) by using a two-phase solvent system composed of ethyl acetate-n-butanol-water (1:6:7, v/v/v). From 1.0 g of the extract, syringaresinol 4',4"-di-o-β-d-glucopyranoside (I, 20.2 mg),, syringin (II, 56.8 mg), sinapaldehyde glucoside (III, 26.2 mg),, syringaresinol 4'-o-β-d-glucopyranoside (IV, 20.4 mg), and pedunculoside (V, 45.1 mg) were obtained by one run of TBE-1000A HSCCC instrument with 1000 mL of column volume. Their structures were identified by IR, MS, and 1H and 13C NMR studies. Glycoside I was isolated from this plant for the first time. PMID:25132792

  12. ISOLATION OF GLYCOSIDES FROM THE BARKS OF ILEX ROTUNDA BY HIGH-SPEED COUNTER-CURRENT CHROMATOGRAPHY.

    PubMed

    Wang, Chun; Chao, Zhimao; Sun, Wen; Wu, Xiaoyi; Ito, Yoichiro

    2014-04-01

    Semi-preparative and preparative high-speed counter-current chromatography (HSCCC) were successfully used for isolation of glycosides from 50% ethanol extract of the dried barks of Ilex rotunda Thunb. (Aquifoliaceae) by using a two-phase solvent system composed of ethyl acetate-n-butanol-water (1:6:7, v/v/v). From 1.0 g of the extract, syringaresinol 4',4"-di-o-β-d-glucopyranoside (I, 20.2 mg),, syringin (II, 56.8 mg), sinapaldehyde glucoside (III, 26.2 mg),, syringaresinol 4'-o-β-d-glucopyranoside (IV, 20.4 mg), and pedunculoside (V, 45.1 mg) were obtained by one run of TBE-1000A HSCCC instrument with 1000 mL of column volume. Their structures were identified by IR, MS, and (1)H and (13)C NMR studies. Glycoside I was isolated from this plant for the first time.

  13. Enantioseparation of racemic trans-δ-viniferin using high speed counter-current chromatography based on induced circular dichroism technology.

    PubMed

    Han, Chao; Xu, Jinfang; Wang, Xiaobing; Xu, Xiaoming; Luo, Jianguang; Kong, Lingyi

    2014-01-10

    A preparative chiral high speed counter-current chromatography (HSCCC) method based on induced circular dichroism (ICD) spectrum was developed to separate trans-δ-viniferin (TVN) enantiomers successfully. The important parameters for the chiral HSCCC separation process, including the type of chiral selector (CS), the concentration of chiral selector and the equilibrium temperature, were optimized using induced circular dichroism spectrum. The final separation procedure was established with a biphasic solvent system composed of n-hexane-ethyl acetate-25 mmol L(-1) hydroxypropyl-β-cyclodextrin aqueous solution (5:5:10, v/v/v) in the head-to-tail elution mode at 5 °C. Under optimum chiral HSCCC separation conditions, 8.2mg of (7S, 8S)-TVN (1) and 9.4 mg of (7R, 8R)-TVN (2) were successfully separated from 20mg TVN enantiomers with the purity of 99.51% and 99.36%, respectively.

  14. Isolation and purification of oridonin from the whole plant of Isodon rubescens by high-speed counter-current chromatography.

    PubMed

    He, Fa; Bai, Yuhua; Wang, Jing; Wei, Jing; Yu, Chunyue; Li, Sen; Yang, Weili; Han, Chenghua

    2011-09-14

    Semi-preparative high-speed counter-current chromatography (HSCCC) was successfully used for isolation and purification of oridonin from Isodon rubescens by using a two-phase-solvent system composed of n-hexane-ethyl acetate-methanol-water (2.8:5:2.8:5, v/v/v/v). The targeted compound isolated, collected and purified by HSCCC was analyzed by high performance liquid chromatography (HPLC). A total of 40.6 mg of oridonin with the purity of 73.5% was obtained in less than 100 min from 100 mg of crude Isodon rubescens extract. The chemical structure of the compound was identified by IR, 1H-NMR and 13C-NMR.

  15. Isolation and purification of orientin and vitexin from Trollius chinensis Bunge by high-speed counter-current chromatography.

    PubMed

    Yu, Xiao-Xue; Huang, Jie-Yun; Xu, Dan; Xie, Zhi-Yong; Xie, Zhi-Sheng; Xu, Xin-Jun

    2014-01-01

    Orientin and vitexin are the two main bioactive compounds in Trollius chinensis Bunge. In this study, a rapid method was established for the isolation and purification of orientin and vitexin from T. chinensis Bunge using high-speed counter-current chromatography in one step, with a solvent system of ethyl acetate-ethanol-water (4:1:5, v/v/v). A total of 9.8 mg orientin and 2.1 mg vitexin were obtained from 100 mg of the ethyl acetate extract, with purities of 99.2% and 96.0%, respectively. Their structures were identified by UV, MS and NMR. The method was efficient and convenient, which could be used for the preparative separation of orientin and vitexin from T. chinensis Bunge.

  16. Preparative isolation and purification of three sesquiterpenoid lactones from Eupatorium lindleyanum DC. by high-speed counter-current chromatography.

    PubMed

    Yan, Guilong; Ji, Lilian; Luo, Yuming; Hu, Yonghong

    2012-07-27

    A high-speed counter-current chromatography (HSCCC) method was established for the preparative separation of three sesquiterpenoid lactones from Eupatorium lindleyanum DC. The two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:4:2:3, v/v/v/v) was selected. From 540 mg of the n-butanol fraction of Eupatorium lindleyanum DC., 10.8 mg of 3β-hydroxy-8β-[4'-hydroxytigloyloxy]-costunolide, 17.9 mg of eupalinolide A and 19.3 mg of eupalinolide B were obtained in a one-step HSCCC separation, with purities of 91.8%, 97.9% and 97.1%, respectively, as determined by HPLC. Their structures were further identified by ESI-MS and ¹H-NMR.

  17. Separation and purification of astaxanthin from Phaffia rhodozyma by preparative high-speed counter-current chromatography.

    PubMed

    Du, Xiping; Dong, Congcong; Wang, Kai; Jiang, Zedong; Chen, Yanhong; Yang, Yuanfan; Chen, Feng; Ni, Hui

    2016-09-01

    An effective high-speed counter-current chromatography (HSCCC) method was established for the preparative isolation and purification of astaxanthin from Phaffia rhodozyma. With a two-phase solvent system composed of n-hexane-acetone-ethanol-water (1:1:1:1, v/v/v/v), 100mg crude extract of P. rhodozyma was separated to yield 20.6mg of astaxanthin at 92.0% purity. By further one step silica gel column chromatography, the purity reached 99.0%. The chemical structure of astaxanthin was confirmed by thin layer chromatography (TLC), UV spectroscopy scanning, high performance liquid chromatography with a ZORBAX SB-C18 column and a Waters Nova-pak C18 column, and ESI/MS/MS. PMID:27433984

  18. Preparative separation and purification of gingerols from ginger (Zingiber officinale Roscoe) by high-speed counter-current chromatography.

    PubMed

    Zhan, Kunyou; Xu, Kun; Yin, Hongzong

    2011-06-15

    A novel method for purifying gingerols from ginger was developed using a high-speed counter-current chromatography (HSCCC). The two-phase solvent system such as light petroleum (bp 60-90°C)-ethyl acetate-methanol-water (5:5:6.5:3.5, v/v/v/v) was applied to the separation and purification of 6-, 8- and 10-gingerol from a crude extract of ginger. The experiment yielded 30.2mg of 6-gingerol, 40.5mg of 8-gingerol, 50.5mg of 10-gingerol from 200mg of crude extract in one-step separation. And the purity of these compounds was 99.9%, 99.9% and 99.2%, respectively, as determined by high-performance liquid chromatography (HPLC). Their structures were identified by gas chromatography-mass spectrometry (GC/MS) and (1)H, (13)C nuclear magnetic resonance (NMR). PMID:25213983

  19. Isolation and purification of canthaxanthin from the microalga Chlorella zofingiensis by high-speed counter-current chromatography.

    PubMed

    Hua-Bin, Li; Fan, King-Wai; Chen, Feng

    2006-03-01

    Certain microalgae are considered to be a potential source of canthaxanthin, which possesses strong antioxidant and anticancer activities. A high-speed counter-current chromatography (HSCCC) method was developed for the separation and purification of canthaxanthin from the microalga Chlorella zofingiensis. The crude canthaxanthin was obtained by extraction with organic solvents after the microalgal sample had been saponified. Preparative HSCCC, with a two-phase solvent system composed of n-hexane-ethanol-water (10:9:1 v/v), was successfully performed yielding canthaxanthin at 98.7% purity from 150 mg of the crude extract (2.1% canthaxanthin) in a one-step separation. The recovery of canthaxanthin was 92.3%. This was the first report that canthaxanthin was successfully separated and purified from microalgae.

  20. Sensitivity of Global Sea-Air CO2 Flux to Gas Transfer Algorithms, Climatological Wind Speeds, and Variability of Sea Surface Temperature and Salinity

    NASA Technical Reports Server (NTRS)

    McClain, Charles R.; Signorini, Sergio

    2002-01-01

    Sensitivity analyses of sea-air CO2 flux to gas transfer algorithms, climatological wind speeds, sea surface temperatures (SST) and salinity (SSS) were conducted for the global oceans and selected regional domains. Large uncertainties in the global sea-air flux estimates are identified due to different gas transfer algorithms, global climatological wind speeds, and seasonal SST and SSS data. The global sea-air flux ranges from -0.57 to -2.27 Gt/yr, depending on the combination of gas transfer algorithms and global climatological wind speeds used. Different combinations of SST and SSS global fields resulted in changes as large as 35% on the oceans global sea-air flux. An error as small as plus or minus 0.2 in SSS translates into a plus or minus 43% deviation on the mean global CO2 flux. This result emphasizes the need for highly accurate satellite SSS observations for the development of remote sensing sea-air flux algorithms.

  1. A fully-coupled implicit method for thermo-chemical nonequilibrium air at sub-orbital flight speeds

    NASA Technical Reports Server (NTRS)

    Park, Chul; Yoon, Seokkwan

    1989-01-01

    A CFD technique is described in which the finite-rate chemistry in thermal and chemical nonequilibrium air is fully and implicitly coupled with the fluid motion. Developed for use in the suborbital hypersonic flight speed range, the method accounts for nonequilibrium vibrational and electronic excitation and dissociation, but not ionization. The steady-state solution to the resulting system of equations is obtained by using a lower-upper factorization and symmetric Gauss-Seidel sweeping technique through Newton iteration. Inversion of the left-hand-side matrices is replaced by scalar multiplications through the use of the diagonal dominance algorithm. The code, named CENS2H (Compressible-Euler-Navier-Stokes Two-Dimensional Hypersonic), is fully vectorized and requires about 8.8 x 10 to the -5th sec per node point per iteration using a Cray X-MP computer. Converged solutions are obtained after about 2400 iterations. Sample calculations are made for a circular cylinder and a 10 percent airfoil at 5 deg angle of attack. The calculated cylinder flow field agrees with that obtained experimentally. The code predicts a 10 percent change in lift, drag, and pitching moment for the airfoil due to the thermochemical phenomena.

  2. High speed, intermediate resolution, large area laser beam induced current imaging and laser scribing system for photovoltaic devices and modules

    NASA Astrophysics Data System (ADS)

    Phillips, Adam B.; Song, Zhaoning; DeWitt, Jonathan L.; Stone, Jon M.; Krantz, Patrick W.; Royston, John M.; Zeller, Ryan M.; Mapes, Meghan R.; Roland, Paul J.; Dorogi, Mark D.; Zafar, Syed; Faykosh, Gary T.; Ellingson, Randy J.; Heben, Michael J.

    2016-09-01

    We have developed a laser beam induced current imaging tool for photovoltaic devices and modules that utilizes diode pumped Q-switched lasers. Power densities on the order of one sun (100 mW/cm2) can be produced in a ˜40 μm spot size by operating the lasers at low diode current and high repetition rate. Using galvanostatically controlled mirrors in an overhead configuration and high speed data acquisition, large areas can be scanned in short times. As the beam is rastered, focus is maintained on a flat plane with an electronically controlled lens that is positioned in a coordinated fashion with the movements of the mirrors. The system can also be used in a scribing mode by increasing the diode current and decreasing the repetition rate. In either mode, the instrument can accommodate samples ranging in size from laboratory scale (few cm2) to full modules (1 m2). Customized LabVIEW programs were developed to control the components and acquire, display, and manipulate the data in imaging mode.

  3. Air Entrainment and Thermal Evolution of Pyroclastic Density Currents at Tungurahua, Ecuador

    NASA Astrophysics Data System (ADS)

    Benage, M. C.; Dufek, J.; Mothes, P. A.

    2015-12-01

    The entrainment of air into pyroclastic density currents (PDCs) impacts the thermal profile and evolution of the current. However, the associated hazards and opaqueness of PDCs make it difficult to discern internal dynamics and entrainment through direct observations. In this work, we use a three-dimensional multiphase Eulerian-Eulerian-Lagrangian (EEL) model, deposit descriptions, and pyroclast field data, such as paleomagnetic and rind thickness, to study the entrainment efficiency and thus the thermal history of PDCs down the Juive Grande quebrada during the August 16-17th 2006 eruption of Tungurahua volcano. We conclude that 1) the efficient entrainment of ambient air cools the nose and upper portion of the PDCs by 30-60% of the original temperature, 2) PDCs with an initial temperature of 727 °C are on average more efficient at entraining ambient air than PDCs with an initial temperature of 327 °C, 3) the channelized PDCs develop a particle concentration gradient with a concentrated bed load region and suspended load region that leads to a large vertical temperature gradient, and 4) observations and pyroclast temperatures and textures suggest that the PDCs had temperatures greater than 327 °C in the bed load region while the upper, exterior portion of the currents cooled down to temperatures less than 100 °C. By combining field data and numerical models, the structure and dynamics of a PDC can be deduced for these relatively common small volume PDCs.

  4. Bird flight and airplane flight. [instruments to measure air currents and flight characteristics

    NASA Technical Reports Server (NTRS)

    Magnan, A.

    1980-01-01

    Research was based on a series of mechanical, electrical, and cinematographic instruments developed to measure various features of air current behavior as well as bird and airplane flight. Investigation of rising obstruction and thermal currents led to a theory of bird flight, especially of the gliding and soaring types. It was shown how a knowledge of bird flight can be applied to glider and ultimately motorized aircraft construction. The instruments and methods used in studying stress in airplanes and in comparing the lift to drag ratios of airplanes and birds are described.

  5. Significance of High-Speed Air Temperature Measurements in the Sampling Cell of a Closed-Path Gas Analyzer with a Short Tube

    NASA Astrophysics Data System (ADS)

    Kathilankal, James; Fratini, Gerardo; Burba, George

    2015-04-01

    Eddy covariance gas analyzers measure gas content in a known volume, thus essentially measuring gas density. The fundamental flux equation, however, is based on the dry mole fraction. The relationship between dry mole fraction and density is regulated by the ideal gas law describing the processes of temperature- and pressure-related expansions and contractions, and by the law of partial pressures, describing the process of dilution. As a result, this relationship depends on water vapor content, temperature and pressure of the air sample. If the instrument is able to output precise high-speed dry mole fraction, the flux processing is significantly simplified and WPL density terms accounting for the air density fluctuations are no longer required. This should also lead to the reduction in uncertainties associated with the density terms resulting from the eddy covariance measurements of sensible and latent heat fluxes used in these terms. In this framework, three main measurement approaches may be considered: Open-path approach Outputting correct high-speed dry mole fraction from the open-path instrument is difficult because of complexities with maintaining reliable fast temperature measurements integrated over the entire measuring path, and also because of extraordinary challenges with accurate measurements of fast pressure in the open air flow. Classical long-tube closed-path approach For instruments utilizing traditional long-tube closed-path design, with tube length 1000 or more times the tube diameter, the fast dry mole fraction can be used successfully when instantaneous fluctuations in the air temperature of the sampled air are effectively dampened to negligible levels, instantaneous pressure fluctuations are regulated or negligible, and water vapor is measured simultaneously with gas or the air sample is dried. Short-tube closed-path approach, the enclosed design For instruments with a short-tube enclosed design, most - but not all - of the temperature

  6. Understanding exposure from natural gas drilling puts current air standards to the test.

    PubMed

    Brown, David; Weinberger, Beth; Lewis, Celia; Bonaparte, Heather

    2014-01-01

    Case study descriptions of acute onset of respiratory, neurologic, dermal, vascular, abdominal, and gastrointestinal sequelae near natural gas facilities contrast with a subset of emissions research, which suggests that there is limited risk posed by unconventional natural gas development (UNGD). An inspection of the pathophysiological effects of acute toxic actions reveals that current environmental monitoring protocols are incompatible with the goal of protecting the health of those living and working near UNGD activities. The intensity, frequency, and duration of exposures to toxic materials in air and water determine the health risks to individuals within a population. Currently, human health risks near UNGD sites are derived from average population risks without adequate attention to the processes of toxicity to the body. The objective of this paper is to illustrate that current methods of collecting emissions data, as well as the analyses of these data, are not sufficient for accurately assessing risks to individuals or protecting the health of those near UNGD sites. Focusing on air pollution impacts, we examined data from public sources and from the published literature. We compared the methods commonly used to evaluate health safety near UNGD sites with the information that would be reasonably needed to determine plausible outcomes of actual exposures. Such outcomes must be based on the pathophysiological effects of the agents present and the susceptibility of residents near these sites. Our study has several findings. First, current protocols used for assessing compliance with ambient air standards do not adequately determine the intensity, frequency or durations of the actual human exposures to the mixtures of toxic materials released regularly at UNGD sites. Second, the typically used periodic 24-h average measures can underestimate actual exposures by an order of magnitude. Third, reference standards are set in a form that inaccurately determines health

  7. Change of 180 degrees in the direction of a uniform current of air

    NASA Technical Reports Server (NTRS)

    Witoszynski, C

    1926-01-01

    In the construction of aerodynamic tunnels, it is a very important matter to obtain a uniform current of air in the sections where measurements are to be made. The straight type ordinarily used for attaining a uniform current and generally recommended for use, has great defects. If we desire to avoid these defects, it is well to give the canals of the tunnel such a form that the current, after the change of direction of its asymptotes, approximates a uniform and rectilinear movement. But for this, the condition must be met that at no place does the flow exceed the maximum velocity assumed, equal to the velocity in the straight parts of the canal.

  8. Impacts of current and projected oil palm plantation expansion on air quality over Southeast Asia

    NASA Astrophysics Data System (ADS)

    Silva, Sam J.; Heald, Colette L.; Geddes, Jeffrey A.; Austin, Kemen G.; Kasibhatla, Prasad S.; Marlier, Miriam E.

    2016-08-01

    Over recent decades oil palm plantations have rapidly expanded across Southeast Asia (SEA). According to the United Nations, oil palm production in SEA increased by a factor of 3 from 1995 to 2010. We investigate the impacts of current (2010) and near-term future (2020) projected oil palm expansion in SEA on surface-atmosphere exchange and the resulting air quality in the region. For this purpose, we use satellite data, high-resolution land maps, and the chemical transport model GEOS-Chem. Relative to a no oil palm plantation scenario (˜ 1990), overall simulated isoprene emissions in the region increased by 13 % due to oil palm plantations in 2010 and a further 11 % in the near-term future. In addition, the expansion of palm plantations leads to local increases in ozone deposition velocities of up to 20 %. The net result of these changes is that oil palm expansion in SEA increases surface O3 by up to 3.5 ppbv over dense urban regions, and in the near-term future could rise more than 4.5 ppbv above baseline levels. Biogenic secondary organic aerosol loadings also increase by up to 1 µg m-3 due to oil palm expansion, and could increase by a further 2.5 µg m-3 in the near-term future. Our analysis indicates that while the impact of recent oil palm expansion on air quality in the region has been significant, the retrieval error and sensitivity of the current constellation of satellite measurements limit our ability to observe these impacts from space. Oil palm expansion is likely to continue to degrade air quality in the region in the coming decade and hinder efforts to achieve air quality regulations in major urban areas such as Kuala Lumpur and Singapore.

  9. Isolation and purification of prenylated phenolics from Amorpha fruticosa by high-speed counter-current chromatography.

    PubMed

    Chen, Chu; Wu, Yan; Chen, Yang; Du, Leilei

    2015-08-01

    Prenylated phenolics such as amorfrutins are recently identified potent anti-inflammatory and antidiabetic natural products. In this work, high-speed counter-current chromatography was investigated for the isolation and purification of prenylated phenolics from the fruits of Amorpha fruticosa by using a two-phase solvent system composed of n-hexane/ethanol/water (5:4:1, v/v). As a result, 14.2 mg of 5,7-dihydroxy-8-geranylflavanone, 10.7 mg of amorfrutin A and 17.4 mg of amorfrutin B were obtained from 200 mg of n-hexane-soluble crude extract in one step within 250 min. The purities of 5,7-dihydroxy-8-geranylflavanone, amorfrutins A and B were 95.2, 96.7 and 97.1%, respectively, as determined by ultra high performance liquid chromatography. The structural identification was performed by mass spectrometry and (1) H and (13) C NMR spectroscopy. The results indicated that the established method is an efficient and convenient way to purified prenylated phenolics from A. fruticosa extract.

  10. [Preparative isolation and purification of the active components from Viticis Fructus by high-speed counter-current chromatography].

    PubMed

    Guan, Renjun; Wang, Daijie; Yu, Zongyuan; Wang, Xiao; Lan, Tianfeng

    2010-11-01

    Vitex trifolia L. var. simplicifolia Cham. is widely distributed in Asia, and its fruits are used as a folk medicine for headaches, colds, migraine, eyepain, etc. In order to effectively separate high-purity active components from the seeds of Vitex trifolia L. var. simplicifolia Cham., a high-speed counter-current chromatography (HSCCC) procedure was performed to separate four components from the crude extract of the fruits. A two-phase solvent system composed of light petroleum-ethyl acetate-methanol-water (3:6: 3.6: 3, v/v/v/ v) was used. Within 230 min, 23 mg of 4-hydroxybenzoic acid, 15 mg of 3,6,7-trimethylquercetagetin, 24 mg of casticin and 5 mg of artemetin were obtained from 250 mg of the crude extract of Viticis Fructus in one-step elution under the conditions of a flow rate of 1.5 mL/min, 800 r/min and the detection wavelength of 254 nm. The purities of the four fractions were 93.1%, 97.3%, 98.7% and 98.5%, respectively. The obtained fractions were analyzed by high performance liquid chromatography (HPLC), and identified by electrospray ionization mass spectrometry (ESI-MS), 1H-nuclear magnetic resonance (NMR) and 13C-NMR. The results indicate that HSCCC is a powerful technique for the purification of active components from Viticis Fructus.

  11. Application of preparative high-speed counter-current chromatography for separation and purification of arctiin from Fructus Arctii.

    PubMed

    Wang, Xiao; Li, Fuwei; Sun, Qinglei; Yuan, Jingpeng; Jiang, Ting; Zheng, Chengchao

    2005-01-21

    Following an initial clean-up step on the AB-8 resin (polystyrene resin, 0.3-1.25 mm: NanKai Chemical Factory, Tianjin, China), high-speed counter-current chromatography (HSCCC) was used to purify an arctiin from an extract of the fruits of the Arctium lappa L. Arctiin is a major lignan compound in the traditional Chinese medicinal herb A. lappa L. The two-phase solvent system used was composed of ethyl acetate-n-butanol-ethanol-water at an optimized volume ratio of 5:0.5:1:5 (v/v/v/v). The upper phase was used as the mobile phase in the head to tail elution mode. A total amount of 159 mg of arctiin at 98% purity was obtained from 350 mg of the crude extract (containing 49% arctiin) with 91% recovery. The preparative isolation and purification of arctiin by HSCCC was completed in 5 h in a separation. Identification of the target compound was performed by LC-electrospray ionization MS and 13C-NMR. The structure of the product was further confirmed by comparison with authentic sample (National Institute of the Control of Pharmaceutical and Biological Products, Beijing, China).

  12. Preparative Purification of Anti-Proliferative Diarylheptanoids from Betula platyphylla by High-Speed Counter-Current Chromatography.

    PubMed

    Cho, Namki; Kim, Hyun Woo; Kim, Tae Bum; Ransom, Tanya T; Beutler, John A; Sung, Sang Hyun

    2016-01-01

    A simple and rapid method using high-speed counter-current chromatography (HSCCC), along with bioassay-guided fractionation based on the anti-proliferative activity against renal and colon cancer cells, has been developed for the preparative separation of aceroside VIII (1) and platyphylloside (2) from Betula platyphylla. A solvent system composed of ethyl acetate/acetonitrile/water (1:0.1:1, v/v/v) was optimized for the separation. The upper phase was used as the stationary phase, and the lower phase was used as the mobile phase. Among these isolated diarylheptanoids, platyphylloside (2) showed anti-proliferative activity in the COLO205 and KM12 colon cells and renal cancer cell lines A498, U031, as well as in MG63 and MG 63.3 osteosarcoma cells. In addition, it showed dose dependent inhibitory effects in the NCI 60 cell line assay. These results suggest that the diarylheptanoids isolated from B. platyphylla with an efficient HSCCC method could be potential multi-targeted therapeutic agents for cancer.

  13. Separation of phenolic acids and flavonoids from Trollius chinensis Bunge by high speed counter-current chromatography.

    PubMed

    Qin, Yanhua; Liang, Yizeng; Ren, Dabing; Qiu, Ximin; Li, Xi

    2015-09-15

    In this work, eleven compounds were successfully separated from Trollius chinensis Bunge by using a two-step high-speed counter-current chromatography (HSCCC) method. NRTL-SAC (nonrandom two-liquid segment activity coefficient) method, a newly developed solvent system selection strategy, was applied to screening the suitable biphasic liquid systems. Hexane/ethyl acetate/ethanol/water (3:7:3:7, v/v) solvent system was used in the first step, while the hexane/ethyl acetate/methanol/water (1:2:1:2, 1:4:1:4, 1:9:1:9, v/v) systems were employed in the second step. The chemical structures of the separated compounds were identified by UV, high resolution ESI-MS and MS/MS data. The separated compounds are 3,4-dihydroxyphenylethanol (1), vanillic acid (2), orientin (3), vitexin (4), veratric acid (5), 2″-O-(3‴, 4‴-dimethoxybenzoyl) orientin (6), 2″-O-feruloylorientin (7), 2″-O-feruloylvitexin (8), 2″-O-(2‴-methylbutyryl) vitexin (9), 2″-O-(2‴-methylbutyryl) isoswertiajaponin (10), 2″-O-(2‴-methylbutyryl) isoswertisin (11). The results demonstrate that HSCCC is a powerful tool for the separation of compounds from extremely complex samples.

  14. Purification of two triterpenoids from Schisandra chinensis by macroporous resin combined with high-speed counter-current chromatography.

    PubMed

    Zhu, Lijie; Li, Bin; Liu, Xiuying; Meng, Xianjun

    2014-10-01

    A method for preparative purification of corosolic acid and nigranoic acid from Schisandra chinensis (SC) was established using a combination of macroporous absorption resin column separation and high-speed counter-current chromatography (HSCCC). The crude extracts obtained from SC using 70% ethanol were separated on a macroporous resin column and then eluted with a graded ethanol series. The 70% ethanol fraction was used as the sample for separation of the two triterpenoids by HSCCC. The two-phase solvent system used for HSCCC separation was chloroform-n-butanol-methanol-water (10:0.5:7:4, v/v/v/v). The upper phase was used as the stationary phase of HSCCC. Corosolic acid (16.4 mg) of 96.3% purity and nigranoic acid (9.5 mg) of 98.9% purity were obtained in a one-step HSCCC separation from 100 mg of the sample. The structures of corosolic acid and nigranoic acid were identified by (1)H-nuclear magnetic resonance (NMR) and (13)C-NMR.

  15. Preparative purification of five bioactive components from Agrimonia pilosa Ledeb by high-speed counter-current chromatography.

    PubMed

    Wang, Yan; Liu, Mozhen; Zheng, Lingli; Yin, Lianhong; Xu, Lina; Qi, Yan; Ma, Xiaochi; Liu, Kexin; Peng, Jinyong

    2012-08-01

    High-speed counter-current chromatography (HSCCC) coupled with ultraviolet (UV) detection or evaporative light-scattering detection was successfully applied for preparative separation of five bioactive compounds from Agrimonia pilosa Ledeb. In preliminary process, D101 macroporous resin was used to separate the crude extract of the plant and four fractions (20, 40, 50, and 60% aqueous ethanol elutions) were produced. Then, these fractions were directly subjected to HSCCC purification. Five chemicals including taxifolin-3-glucoside (6.4 mg), quercetin-3-rhamnoside (13.0 mg), tiliroside (14.7 mg), agrimonolide (21.4 mg), and tormentic acid (29.8 mg) with the purities of 94.24, 95.37, 97.42, 95.29, and 96.34% were separated from each 200 mg prepared fraction. The purities were analyzed by high-performance liquid chromatography, and the chemical structures of the products were identified by UV detection, mass spectrometry, nuclear magnetic resonance, and the standards. This paper used a simple method to separate five bioactive compounds from A. pilosa Ledeb, and it could provide a new idea for the purification of bioactive compounds from other medicinal plants.

  16. Purification of two triterpenoids from Schisandra chinensis by macroporous resin combined with high-speed counter-current chromatography.

    PubMed

    Zhu, Lijie; Li, Bin; Liu, Xiuying; Meng, Xianjun

    2014-10-01

    A method for preparative purification of corosolic acid and nigranoic acid from Schisandra chinensis (SC) was established using a combination of macroporous absorption resin column separation and high-speed counter-current chromatography (HSCCC). The crude extracts obtained from SC using 70% ethanol were separated on a macroporous resin column and then eluted with a graded ethanol series. The 70% ethanol fraction was used as the sample for separation of the two triterpenoids by HSCCC. The two-phase solvent system used for HSCCC separation was chloroform-n-butanol-methanol-water (10:0.5:7:4, v/v/v/v). The upper phase was used as the stationary phase of HSCCC. Corosolic acid (16.4 mg) of 96.3% purity and nigranoic acid (9.5 mg) of 98.9% purity were obtained in a one-step HSCCC separation from 100 mg of the sample. The structures of corosolic acid and nigranoic acid were identified by (1)H-nuclear magnetic resonance (NMR) and (13)C-NMR. PMID:24220992

  17. Preparative separation of polyphenols from the flowers of Paeonia lactiflora Pall. by high-speed counter-current chromatography.

    PubMed

    Shu, Xikai; Duan, Wenjuan; Liu, Feng; Shi, Xingang; Geng, Yanling; Wang, Xiao; Yang, Bingtian

    2014-02-01

    High-speed counter-current chromatography was used to separate and purify polyphenols for the first time from the flowers of Paeonia lactiflora Pall. with two solvent systems as follows: petroleum ether-ethyl acetate-H2O (1:9:10, v/v/v/v) and petroleum ether-ethyl acetate-butanol-H2O (1:9:0.5:10, v/v/v/v). Eight compounds were separated successfully in single run which were identified as quercetin-3-O-(6″-O-galloyl)-glucoside (I, 41.5 mg), 1,2,3,4,6-trigalloyl-β-D-glucose (II, 106.2mg), quercetin-3-O-β-D-glucoside (III, 42.3 mg), kaempferol-3-O-(6″-O-galloyl)-glucoside (IV, 23.5 mg), isohamnetin-3-O-β-D-glucoside (V, 34.1 mg), kaempferol (VI, 14.8 mg), kaempferol-3-O-β-D-glucoside (VII, 32.6 mg), kaempferol-7-O-β-D-glucoside (VIII, 23.8 mg) by electrospray ionization-mass spectrometry (ESI-MS) and nuclear magnetic resonance (NMR). The purities of compounds I-VIII were all over 97.0% as determined by HPLC. PMID:24406305

  18. Learning Styles of Pilots Currently Qualified in United States Air Force Aircraft

    NASA Technical Reports Server (NTRS)

    Kanske, Craig A.

    2001-01-01

    Kolb's Learning Style Inventory was used to identify the predominant learning styles of pilots currently qualified in United States Air Force aircraft. The results indicate that these pilots show a significant preference for facts and things over people and feelings. By understanding the preferred learning styles of the target population, course material can be developed that take advantage of the strengths of these learning styles. This information can be especially useful in the future design of cockpit resource management training. The training program can be developed to demonstrate both that there are different learning styles and that it is possible to take advantage of the relative strengths of each of these learning styles.

  19. Current state and prospects of researches on the control of turbulent boundary layer by air blowing

    NASA Astrophysics Data System (ADS)

    Kornilov, V. I.

    2015-07-01

    The paper presents the analytical review of the current state of the investigations and development trends on the problem of turbulent friction and aerodynamic drag reduction in simple model configurations, which is among key ones in modern aeromechanics. Under consideration is the modern fast progressing method of the turbulent flow control by air- and other gases (micro)blowing through a permeable surface, which is utilized in incompressible and compressible turbulent boundary layers. Several computational results to understand the essential flow physics are also included. The problem of simulation of the flow over a perforated wall where some ambiguities, in particular, at the permeable/impermeable boundary being still remained is discussed. Special attention is paid to the analysis of most important experimental and numerical results obtained with the air blowing through a finely-perforated surface, analysis of the physical peculiarities and regularities of the flow with the blowing, probability to describe the properties of such a flow within simple approach frameworks, evaluation of the efficiency of this control method, as well as the trends and opportunities of this method progress in view of state-of-the-art achievements. Although this technology has a penalty for developing the effective turbulent-flow control method, some modifications of the air blowing are an attractive alternative for real applications.

  20. Open-air direct current plasma jet: Scaling up, uniformity, and cellular control

    NASA Astrophysics Data System (ADS)

    Wu, S.; Wang, Z.; Huang, Q.; Lu, X.; Ostrikov, K.

    2012-10-01

    Atmospheric-pressure plasma jets are commonly used in many fields from medicine to nanotechnology, yet the issue of scaling the discharges up to larger areas without compromising the plasma uniformity remains a major challenge. In this paper, we demonstrate a homogenous cold air plasma glow with a large cross-section generated by a direct current power supply. There is no risk of glow-to-arc transitions, and the plasma glow appears uniform regardless of the gap between the nozzle and the surface being processed. Detailed studies show that both the position of the quartz tube and the gas flow rate can be used to control the plasma properties. Further investigation indicates that the residual charges trapped on the inner surface of the quartz tube may be responsible for the generation of the air plasma plume with a large cross-section. The spatially resolved optical emission spectroscopy reveals that the air plasma plume is uniform as it propagates out of the nozzle. The remarkable improvement of the plasma uniformity is used to improve the bio-compatibility of a glass coverslip over a reasonably large area. This improvement is demonstrated by a much more uniform and effective attachment and proliferation of human embryonic kidney 293 (HEK 293) cells on the plasma-treated surface.

  1. Material Properties Governing Co-Current Flame Spread: The Effect of Air Entrainment

    NASA Technical Reports Server (NTRS)

    Coutin, Mickael; Rangwala, Ali S.; Torero, Jose L.; Buckley, Steven G.

    2003-01-01

    A study on the effects of lateral air entrainment on an upward spreading flame has been conducted. The fuel is a flat PMMA plate of constant length and thickness but variable width. Video images and surface temperatures have allowed establishing the progression of the pyrolyis front and on the flame stand-off distance. These measurements have been incorporated into a theoretical formulation to establish characteristic mass transfer numbers ("B" numbers). The mass transfer number is deemed as a material related parameter that could be used to assess the potential of a material to sustain co-current flame spread. The experimental results show that the theoretical formulation fails to describe heat exchange between the flame and the surface. The discrepancies seem to be associated to lateral air entrainment that lifts the flame off the surface and leads to an over estimation of the local mass transfer number. Particle Image Velocimetry (PIV) measurements are in the process of being acquired. These measurements are intended to provide insight on the effect of air entrainment on the flame stand-off distance. A brief description of the methodology to be followed is presented here.

  2. Open-air direct current plasma jet: Scaling up, uniformity, and cellular control

    SciTech Connect

    Wu, S.; Wang, Z.; Huang, Q.; Lu, X.; Ostrikov, K.

    2012-10-15

    Atmospheric-pressure plasma jets are commonly used in many fields from medicine to nanotechnology, yet the issue of scaling the discharges up to larger areas without compromising the plasma uniformity remains a major challenge. In this paper, we demonstrate a homogenous cold air plasma glow with a large cross-section generated by a direct current power supply. There is no risk of glow-to-arc transitions, and the plasma glow appears uniform regardless of the gap between the nozzle and the surface being processed. Detailed studies show that both the position of the quartz tube and the gas flow rate can be used to control the plasma properties. Further investigation indicates that the residual charges trapped on the inner surface of the quartz tube may be responsible for the generation of the air plasma plume with a large cross-section. The spatially resolved optical emission spectroscopy reveals that the air plasma plume is uniform as it propagates out of the nozzle. The remarkable improvement of the plasma uniformity is used to improve the bio-compatibility of a glass coverslip over a reasonably large area. This improvement is demonstrated by a much more uniform and effective attachment and proliferation of human embryonic kidney 293 (HEK 293) cells on the plasma-treated surface.

  3. High-speed counter-current chromatography in separation of betacyanins from flowers of red Gomphrena globosa L. cultivars.

    PubMed

    Spórna-Kucab, Aneta; Hołda, Ewelina; Wybraniec, Sławomir

    2016-10-15

    Antioxidant and possible chemopreventive properties of betacyanins, natural plant pigments, contribute to a growing interest in their chemistry and separation. Mixtures of betacyanins from fresh red Gomphrena globosa L. cultivar flowers were separated in three highly polar solvent systems by high-speed counter-current chromatography (HSCCC) for a direct comparison of their separation effectiveness. Three samples of crude extract (600mg) were run on semi-preparative scale in solvent system (NH4)2SO4soln - EtOH (2.0:1.0, v/v) (system I) and the modified systems: EtOH - ACN - 1-PrOH - (NH4)2SO4satd.soln - H2O (0.5:0.5:0.5:1.2:1.0, v/v/v/v/v) (system II) and EtOH - ACN - (NH4)2SO4satd.soln - H2O (1.0:0.5:1.2:1.0, v/v/v/v) (system III). The systems were used in the head-to-tail (system I) or tail-to-head (systems II and III) mode. The flow rate of the mobile phase was 2.0ml/min and the column rotation speed was 860rpm. The retention of the stationary phase was 52.0% (system I), 80.2% (systems II) and 82.0% (system III). The betacyanins in the crude extract as well as HSCCC fractions were analyzed by LC-MS/MS. System I was applied for the first time in HSCCC for the separation of betacyanins and was quite effective in separation of amaranthine and 17-decarboxy-amaranthine (αI=1.19) and very effective for 17-decarboxy-amaranthine and betanin (αI=2.20). Modification of system I with acetonitrile (system III) as well as acetonitrile and propanol (system II) increased their separation effectiveness. Systems II-III enable complete separation of 17-decarboxy-amaranthine (KD(II)=2.94,KD(III)=2.42) and betanin (KD(II)=2.46,KD(III)=1.10) as well as betanin and gomphrenin I (KD(II)=1.62, KD(III)=0.74). In addition, separation of amaranthine and 17-decarboxy-amaranthine is the most effective in system II, therefore, this system proved to be the most suitable for the separation of all polar betacyanins. PMID:27649502

  4. High-speed counter-current chromatography in separation of betacyanins from flowers of red Gomphrena globosa L. cultivars.

    PubMed

    Spórna-Kucab, Aneta; Hołda, Ewelina; Wybraniec, Sławomir

    2016-10-15

    Antioxidant and possible chemopreventive properties of betacyanins, natural plant pigments, contribute to a growing interest in their chemistry and separation. Mixtures of betacyanins from fresh red Gomphrena globosa L. cultivar flowers were separated in three highly polar solvent systems by high-speed counter-current chromatography (HSCCC) for a direct comparison of their separation effectiveness. Three samples of crude extract (600mg) were run on semi-preparative scale in solvent system (NH4)2SO4soln - EtOH (2.0:1.0, v/v) (system I) and the modified systems: EtOH - ACN - 1-PrOH - (NH4)2SO4satd.soln - H2O (0.5:0.5:0.5:1.2:1.0, v/v/v/v/v) (system II) and EtOH - ACN - (NH4)2SO4satd.soln - H2O (1.0:0.5:1.2:1.0, v/v/v/v) (system III). The systems were used in the head-to-tail (system I) or tail-to-head (systems II and III) mode. The flow rate of the mobile phase was 2.0ml/min and the column rotation speed was 860rpm. The retention of the stationary phase was 52.0% (system I), 80.2% (systems II) and 82.0% (system III). The betacyanins in the crude extract as well as HSCCC fractions were analyzed by LC-MS/MS. System I was applied for the first time in HSCCC for the separation of betacyanins and was quite effective in separation of amaranthine and 17-decarboxy-amaranthine (αI=1.19) and very effective for 17-decarboxy-amaranthine and betanin (αI=2.20). Modification of system I with acetonitrile (system III) as well as acetonitrile and propanol (system II) increased their separation effectiveness. Systems II-III enable complete separation of 17-decarboxy-amaranthine (KD(II)=2.94,KD(III)=2.42) and betanin (KD(II)=2.46,KD(III)=1.10) as well as betanin and gomphrenin I (KD(II)=1.62, KD(III)=0.74). In addition, separation of amaranthine and 17-decarboxy-amaranthine is the most effective in system II, therefore, this system proved to be the most suitable for the separation of all polar betacyanins.

  5. Air pollution toxicology--a brief review of the role of the science in shaping the current understanding of air pollution health risks.

    PubMed

    Stanek, Lindsay Wichers; Brown, James S; Stanek, John; Gift, Jeff; Costa, Daniel L

    2011-03-01

    Human and animal toxicology has had a profound impact on our historical and current understanding of air pollution health effects. Early animal toxicological studies of air pollution had distinctively military or workplace themes. With the discovery that ambient air pollution episodes led to excess illness and death, there became an emergence of toxicological studies that focused on industrial air pollution encountered by the general public. Not only did the pollutants investigated evolve from ambient mixtures to individual pollutants but also the endpoints and outcomes evaluated became more sophisticated, resulting in our present state of the science. Currently, a large toxicological database exists for the effects of particulate matter and ozone, and we provide a focused review of some of the major contributions to the biological understanding for these two "criteria" air pollutants. A limited discussion of the toxicological advancements in the scientific knowledge of two hazardous air pollutants, formaldehyde and phosgene, is also included. Moving forward, the future challenge of air pollution toxicology lies in the health assessment of complex mixtures and their interactions, given the projected impacts of climate change and altered emissions on ambient conditions. In the coming years, the toxicologist will need to be flexible and forward thinking in order to dissect the complexity of the biological system itself, as well as that of air pollution in all its varied forms.

  6. Analysis of the Magneto-Hydrodynamic (MHD) Energy Bypass Engine for High-Speed Air-Breathing Propulsion

    NASA Technical Reports Server (NTRS)

    Riggins, David W.

    2002-01-01

    The performance of the MHD energy bypass air-breathing engine for high-speed propulsion is analyzed in this investigation. This engine is a specific type of the general class of inverse cycle engines. In this paper, the general relationship between engine performance (specific impulse and specific thrust) and the overall total pressure ratio through an engine (from inlet plane to exit plane) is first developed and illustrated. Engines with large total pressure decreases, regardless of cause or source, are seen to have exponentially decreasing performance. The ideal inverse cycle engine (of which the MHD engine is a sub-set) is then demonstrated to have a significant total pressure decrease across the engine; this total pressure decrease is cycle-driven, degrades rapidly with energy bypass ratio, and is independent of any irreversibility. The ideal MHD engine (inverse cycle engine with no irreversibility other than that inherent in the MHD work interaction processes) is next examined and is seen to have an additional large total pressure decrease due to MHD-generated irreversibility in the decelerator and the accelerator. This irreversibility mainly occurs in the deceleration process. Both inherent total pressure losses (inverse cycle and MHD irreversibility) result in a significant narrowing of the performance capability of the MHD bypass engine. The fundamental characteristics of MHD flow acceleration and flow deceleration from the standpoint of irreversibility and second-law constraints are next examined in order to clarify issues regarding flow losses and parameter selection in the MM modules. Severe constraints are seen to exist in the decelerator in terms of allowable deceleration Mach numbers and volumetric (length) required for meaningful energy bypass (work interaction). Considerable difficulties are also encountered and discussed due to thermal/work choking phenomena associated with the deceleration process. Lastly, full engine simulations utilizing inlet

  7. Low temperature, atmospheric pressure, direct current microplasma jet operated in air, nitrogen and oxygen

    NASA Astrophysics Data System (ADS)

    Mohamed, A.-A. H.; Kolb, J. F.; Schoenbach, K. H.

    2010-12-01

    Micro-plasma jets in atmospheric pressure molecular gases (nitrogen, oxygen, air) were generated by blowing these gases through direct current microhollow cathode discharges (MHCDs). The tapered discharge channel, drilled through two 100 to 200 μm thick molybdenum electrodes separated by a 200 μm thick alumina layer, is 150 to 450 μm in diameter in the cathode and has an opening of 100 to 300 μm in diameter in the anode. Sustaining voltages are 400 to 600 V, the maximum current is 25 mA. The gas temperature of the microplasma inside the microhollow cathode varies between ~2000 K and ~1000 K depending on current, gas, and flow rate. Outside the discharge channel the temperature in the jet can be reduced by manipulating the discharge current and the gas flow to achieve values close to room temperature. This cold microplasma jet can be used for surface treatment of heat sensitive substances, and for sterilization of contaminated areas.

  8. Preparative Separation of Main Ustilaginoidins from Rice False Smut Balls by High-Speed Counter-Current Chromatography

    PubMed Central

    Sun, Weibo; Dong, Xuejiao; Xu, Dan; Meng, Jiajia; Fu, Xiaoxiang; Wang, Xiaohan; Lai, Daowan; Zhou, Ligang; Liu, Yang

    2016-01-01

    Ustilaginoidins are bis-naphtho-γ-pyrone mycotoxins isolated from the rice false smut balls (FSBs) infected by the pathogen Villosiclava virens in rice spikelets on panicles. In order to obtain large amounts of pure ustilaginoidins to further evaluate their biological activities and functions, phytotoxicity on rice, security to human and animals as well as to accelerate their applications as pharmaceuticals, preparative high-speed counter-current chromatography (HSCCC) was successfully applied to the isolation and purification of seven bis-naphtho-γ-pyrone mycotoxins, namely ustilaginoidins A (1), G (2), B (3), H (4), I (5), C (6), and J (7) from the ethyl acetate crude extract of rice FSBs. Both 1 and 2 were prepared by HSCCC from the low-polarity fraction of the crude extract using the two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water at the volume ratio of 6.5:3.5:5.0:5.0. Similarly, 3, 4 and 5 were prepared from the medium-polarity fraction using the system at the volume ratio of 4.0:5.0:5.0:6.0, and 6 and 7 were prepared from the higher-polarity fraction using the system at volume ratio of 3.0:5.0:4.0:6.7. A total of 6.2 mg of 1, 5.1 mg of 2, 3.9 mg of 3, 1.2 mg of 4, 5.7 mg of 5, 3.5 mg of 6, and 6.1 mg of 7 with purities of 88%, 82%, 91%, 80%, 92%, 81% and 83%, respectively, were yielded from total 62 mg fraction samples in three independent HSCCC runs. The structures of the purified ustilaginoidins were characterized by means of physicochemical and spectrometric analysis. PMID:26771638

  9. Separation of betalains from berries of Phytolacca americana by ion-pair high-speed counter-current chromatography.

    PubMed

    Jerz, Gerold; Skotzki, Tanja; Fiege, Kathrin; Winterhalter, Peter; Wybraniec, Sławomir

    2008-05-01

    The first preparative fractionation of betalain pigments by means of ion-pair high-speed counter-current chromatography (IP-HSCCC) from berry extracts of Phytolacca americana (Phytolaccaceae) is presented. A novel HSCCC solvent system consisting of 1-butanol-acetonitrile-water (5:1:6, v/v/v) was applied using ion-pair forming trifluoroacetic acid at low concentration (0.7%, v/v). Affinity of polar betacyanins and betaxanthins to the organic stationary phase of the biphasic HSCCC solvent mixture was considerably improved. Partitioning coefficient values and influence of increasing trifluoroacetic acid additions to the biphasic solvent mixture were measured for all identified betacyanins and betaxanthins. Gentle separation by IP-HSCCC of the injected pigment extract (900 mg) yielded sufficient amounts of the principal pigments 15S-betanin/15R-isobetanin. The pure epimers separated by C18-HPLC were immediately studied by one- and two-dimensional NMR. In the recovered fractions, minor concentrated betacyanins and betaxanthins were significantly enriched by IP-HSCCC and were detected for the first time in the extracts of P. americana. IP-HSCCC and C18-HPLC were shown to be complementary techniques in the isolation procedure of recovering minor concentrated, highly polar and chemically instable betacyanins and betaxanthin from complex plant matrices. Altogether, identification of 17 betalains was achieved by HPLC-diode array detection-electrospray ionization MS/MS in the HSCCC fractions with their respective isomers, also resulting in the tentative elucidation of betacyanins with novel salicylic acid substitution pattern in the berry extracts of P. americana.

  10. Preparative Separation of Main Ustilaginoidins from Rice False Smut Balls by High-Speed Counter-Current Chromatography.

    PubMed

    Sun, Weibo; Dong, Xuejiao; Xu, Dan; Meng, Jiajia; Fu, Xiaoxiang; Wang, Xiaohan; Lai, Daowan; Zhou, Ligang; Liu, Yang

    2016-01-12

    Ustilaginoidins are bis-naphtho-γ-pyrone mycotoxins isolated from the rice false smut balls (FSBs) infected by the pathogen Villosiclava virens in rice spikelets on panicles. In order to obtain large amounts of pure ustilaginoidins to further evaluate their biological activities and functions, phytotoxicity on rice, security to human and animals as well as to accelerate their applications as pharmaceuticals, preparative high-speed counter-current chromatography (HSCCC) was successfully applied to the isolation and purification of seven bis-naphtho-γ-pyrone mycotoxins, namely ustilaginoidins A (1), G (2), B (3), H (4), I (5), C (6), and J (7) from the ethyl acetate crude extract of rice FSBs. Both 1 and 2 were prepared by HSCCC from the low-polarity fraction of the crude extract using the two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water at the volume ratio of 6.5:3.5:5.0:5.0. Similarly, 3, 4 and 5 were prepared from the medium-polarity fraction using the system at the volume ratio of 4.0:5.0:5.0:6.0, and 6 and 7 were prepared from the higher-polarity fraction using the system at volume ratio of 3.0:5.0:4.0:6.7. A total of 6.2 mg of 1, 5.1 mg of 2, 3.9 mg of 3, 1.2 mg of 4, 5.7 mg of 5, 3.5 mg of 6, and 6.1 mg of 7 with purities of 88%, 82%, 91%, 80%, 92%, 81% and 83%, respectively, were yielded from total 62 mg fraction samples in three independent HSCCC runs. The structures of the purified ustilaginoidins were characterized by means of physicochemical and spectrometric analysis.

  11. Preparative isolation and purification of two benzoxazinoid glucosides from Acanthus ilicifolius L. by high-speed counter-current chromatography.

    PubMed

    Yin, Hao; Zhang, Si; Luo, Xiongming; Liu, Yonghong

    2008-09-26

    The first preparative separation of two benzoxazinoids, (2R)-2-O-beta-d-glucopyranosyl-2H-1,4-benzoxazin-3(4H)-one (HBOA-Glc) and (2R)-2-O-beta-d-glucopyranosyl-4-hydroxy-2H-1,4-benzoxazin-3(4H)-one (DIBOA-Glc), by means of high-speed counter-current chromatography (HSCCC) from the n-butanol extract of Acanthus ilicifolius L. is presented. The two-phase solvent system containing ethyl acetate-n-butanol-0.5%NH(4)OH (2:3:5, v/v/v, system B) was selected for the one-step HSCCC separation of HBOA-Glc and DIBOA-Glc according to the partition coefficient values (K) for target compounds and the separation factor (alpha) between the two target compounds. In the one-step HSCCC separation using solvent B, from 100mg n-butanol extract of A. ilicifolius, 6.3 mg HBOA-Glc and 6.8 mg DIBOA-Glc were isolated with purities of 90.3% and 80.2%, respectively. In order to obtain the two target compounds with higher purity, a second separation process was developed comprising two steps. In the two-step separation, the sample was first pre-purified by HSCCC using ethyl acetate-n-butanol-water (2:3:5, v/v/v, system A) solvent system and then purified using solvent system B. A 100-mg amount of the n-butanol extracts of A. ilicifolius was separated to yield 5.8 mg of HBOA-Glc and 4.8 mg of DIBOA-Glc with purities of 97.1% and 94.8%, respectively, which were directly used for NMR analyses.

  12. A Brief Study of the Speed Reduction of Overtaking Airplanes by Means of Air Brakes, Special Report

    NASA Technical Reports Server (NTRS)

    Pearson, H. A.; Amderspm. R. F.

    1942-01-01

    As an aid to airplane designers interested in providing pursuit airplanes with decelerating devices intended to increase the firing time when overtaking another airplane, formulas are given relating the pertinent distances and speeds in horizontal flight to the drag increase required. Charts are given for a representative parasite-drag coefficient from which the drag increase, the time gained, and the closing distance may be found. The charts are made up for three values of the ratio of the final speed of the pursuing airplane to the speed of the pursued airplane and for several values of the ratio of the speed of the pursued airplane to the initial speed of the pursuing airplane. Charts are also given indicating the drag increases obtainable with double split flaps and with conventional propellers. The use of the charts is illustrated by an example in which it is indicated that either double split flaps or, under certain ideal conditions, reversible propellers should provide the speed reductions required.

  13. Separation and purification of hydrolyzable tannin from Geranium wilfordii Maxim by reversed-phase and normal-phase high-speed counter-current chromatography.

    PubMed

    Liu, Dan; Su, Zhiguo; Wang, Changhai; Gu, Ming; Xing, Siliang

    2010-08-01

    Three hydrolyzable tannins, geraniin, corilagin and gallic acid, main active components of Geranium wilfordii Maxim, have been separated and purified in one-step by both reversed-phase and normal-phase high-speed counter-current chromatography. Gallic acid, corilagin and geraniin were purified from 70% aqueous acetone extract of G. wilfordii Maxim with solvent system n-hexane-ethyl acetate-methanol-acetic acid-water (1:10:0.2:0.2:20) by reversed-phase high-speed counter-current chromatography at purities of 94.2, 91.0 and 91.3%, at yields of 89.3, 82.9 and 91.7%, respectively. Gallic acid, corilagin and geraniin were purified with solvent system n-hexane-ethyl acetate-methanol-acetic acid-water (0.2:10:2:1:5) by normal-phase high-speed counter-current chromatography at purities of 85.9, 92.2 and 87.6%, at yields of 87.4, 94.6 and 94.3%, respectively. It was successful for both reversed-phase and normal-phase high-speed counter-current chromatography to separate high-polarity of low-molecular-weight substances.

  14. Simultaneous particle image velocimetry and chemiluminescence visualization of millisecond-pulsed current-voltage-induced perturbations of a premixed propane/air flame

    NASA Astrophysics Data System (ADS)

    Schmidt, Jacob; Kostka, Stanislav; Lynch, Amy; Ganguly, Biswa

    2011-09-01

    The effects of millisecond-wide, pulsed current-voltage-induced behavior in premixed laminar flames have been investigated through the simultaneous collection of particle image velocimetry (PIV) and chemiluminescence data with particular attention paid to the onset mechanisms. Disturbances caused by applied voltages of 2 kV over a 30-mm gap to a downward propagating, atmospheric pressure, premixed propane/air flame with a flow speed near 2 m/s and an equivalence ratio of 1.06 are investigated. The combined PIV and chemiluminescence-based experimental data show the observed disturbance originates only in or near the cathode fall region very close to the burner base. The data also suggest that the coupling mechanism responsible for the flame disturbance behavior is fluidic in nature, developing from the radial positive chemi-ion distribution and an ion-drift current-induced net body force that acts along the annular space discharge distribution in the reaction zone in or near the cathode fall. This net body force causes a reduction in flow speed above these near cathodic regions causing the base of the flame to laterally spread. Also, this effect seems to produce a velocity gradient leading to the transition of a laminar flame to turbulent combustion for higher applied current-voltage conditions as shown in previous work (Marcum and Ganguly in Combust Flame 143:27-36, 2005; Schmidt and Ganguly in 48th AIAA aerospace sciences meeting. Orlando, 2010).

  15. Impact of cercal air currents on singing motor pattern generation in the cricket (Gryllus bimaculatus DeGeer).

    PubMed

    Jacob, Pedro F; Hedwig, Berthold

    2015-11-01

    The cercal system of crickets detects low-frequency air currents produced by approaching predators and self-generated air currents during singing, which may provide sensory feedback to the singing motor network. We analyzed the effect of cercal stimulation on singing motor pattern generation to reveal the response of a singing interneuron to predator-like signals and to elucidate the possible role of self-generated air currents during singing. In fictive singing males, we recorded an interneuron of the singing network while applying air currents to the cerci; additionally, we analyzed the effect of abolishing the cercal system in freely singing males. In fictively singing crickets, the effect of short air stimuli is either to terminate prematurely or to lengthen the interchirp interval, depending on their phase in the chirp cycle. Within our stimulation paradigm, air stimuli of different velocities and durations always elicited an inhibitory postsynaptic potential in the singing interneuron. Current injection in the singing interneuron elicited singing motor activity, even during the air current-evoked inhibitory input from the cercal pathway. The disruptive effects of air stimuli on the fictive singing pattern and the inhibitory response of the singing interneuron point toward the cercal system being involved in initiating avoidance responses in singing crickets, according to the established role of cerci in a predator escape pathway. After abolishing the activity of the cercal system, the timing of natural singing activity was not significantly altered. Our study provides no evidence that self-generated cercal sensory activity has a feedback function for singing motor pattern generation.

  16. Improvement of oxygen transfer coefficient during Penicillium canescens culture. Influence of turbine design, agitation speed, and air flow rate on xylanase production.

    PubMed

    Gaspar, A; Strodiot, L; Thonart, P

    1998-01-01

    To improve xylanase productivity from Penicillium canescens 10-10c culture, an optimization of oxygen supply is required. Because the strain is sensitive to shear forces, leading to lower xylanase productivity as to morphological alteration, vigorous mixing is not desired. The influence of turbine design, agitation speed, and air flow rate on K1a (global mass transfer coefficient, h(-1)) and enzyme production is discussed. K1a values increased with agitation speed and air flow rate, whatever the impeller, in our assay conditions. Agitation had more influence on K1a values than air flow, when a disk-mounted blade's impeller (DT) is used; an opposite result was obtained with a hub-mounted pitched blade's impeller (PBT). Xylanase production appeared as a function of specific power (W/m3), and an optimum was found in 20 and 100 L STRs fitted with DT impellers. On the other hand, the use of a hub-mounted pitched blade impeller (PBT8), instead of a disk-mounted blade impeller (DT4), reduced the lag time of hemicellulase production and increased xylanase productivity 1.3-fold. PMID:18576019

  17. Isolation and purification of the bioactive carotenoid zeaxanthin from the microalga Microcystis aeruginosa by high-speed counter-current chromatography.

    PubMed

    Chen, Feng; Li, Hua-Bin; Wong, Ricky Ngok-Shun; Ji, Bo; Jiang, Yue

    2005-02-01

    High-speed counter-current chromatography was successfully applied for the first time to the isolation and purification of the bioactive carotenoid zeaxanthin from the cyanobacterium Microcystis aeruginosa. The crude zeaxanthin was obtained by extraction with organic solvents after the microalgal sample had been saponified. Preparative high-speed counter-current chromatography with a two-phase solvent system composed of n-hexane-ethyl acetate-ethanol-water (8:2:7:3, v/v/v/v) was successfully performed yielding zeaxanthin at 96.2% purity from 150 mg of the crude extract in a one-step separation. The recovery of zeaxanthin was 91.4%. This was also the first report that zeaxanthin was successfully separated and purified from microalgae.

  18. Comparative histopathological analysis of human pulps after class I cavity preparation with a high-speed air-turbine handpiece or Er:YAG laser

    NASA Astrophysics Data System (ADS)

    Kina, J. F.; Benitez, P. C.; Lizarelli, R. F. Z.; Bagnato, V. S.; Martinez, T. C.; Oliveira, C. F.; Hebling, J.; Costa, C. A. S.

    2008-12-01

    The purpose of this study was to comparatively evaluate the response of human pulps after cavity preparation with different devices. Deep class I cavities were prepared in sound mandibular premolars using either a high-speed air-turbine handpiece (Group 1) or an Er:YAG laser (Group 2). Following total acid etching and the application of an adhesive system, all cavities were restored with composite resin. Fifteen days after the clinical procedure, the teeth were extracted and processed for analysis under optical microscopy. In Group 1 in which the average for the remaining dentin thickness (RDT) between the cavity floor and the coronal pulp was 909.5 μm, a discrete inflammatory response occurred in only one specimen with an RDT of 214 μm. However, tissue disorganization occurred in most specimens. In Group 2 (average RDT = 935.2 μm), the discrete inflammatory pulp response was observed in only one specimen (average RDT = 413 μm). It may be concluded that the high-speed air-turbine handpiece caused greater structural alterations in the pulp, although without inducing inflammatory processes.

  19. Isolation of the new minor constituents dihydropyranochromone and furanocoumarin from fruits of Peucedanum alsaticum L. by high-speed counter-current chromatography.

    PubMed

    Skalicka-Woźniak, Krystyna; Mroczek, Tomasz; Garrard, Ian; Głowniak, Kazimierz

    2009-07-24

    A preparative high-speed counter-current chromatography (HSCCC) method was successfully used for isolation of two new minor compounds--alsaticol and alsaticocoumarin A. A two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:1:1:1) was developed. Compounds were obtained from the dichloromethane extract of Peucedanum alsaticum fruits and their identification was performed with NMR and MS methods. Optimized HSCCC offers a rapid method of obtaining new natural compounds.

  20. Particle size distributions of currently used pesticides in ambient air of an agricultural Mediterranean area

    NASA Astrophysics Data System (ADS)

    Coscollà, Clara; Muñoz, Amalia; Borrás, Esther; Vera, Teresa; Ródenas, Milagros; Yusà, Vicent

    2014-10-01

    This work presents first data on the particle size distribution of 16 pesticides currently used in Mediterranean agriculture in the atmosphere. Particulate matter air samples were collected using a cascade impactor distributed into four size fractions in a rural site of Valencia Region, during July to September in 2012 and from May to July in 2013. A total of 16 pesticides were detected, including six fungicides, seven insecticides and three herbicides. The total concentrations in the particulate phase (TSP: Total Suspended Particulate) ranged from 3.5 to 383.1 pg m-3. Most of the pesticides (such as carbendazim, tebuconazole, chlorpyrifos-ethyl and chlorpyrifos-methyl) were accumulated in the ultrafine-fine (<1 μm) and coarse (2.5-10 μm) particle size fractions. Others like omethoate, dimethoate and malathion were presented only in the ultrafine-fine size fraction (<1 μm). Finally, diuron, diphenylamine and terbuthylazine-desethyl-2-OH also show a bimodal distribution but mainly in the coarse size fractions.

  1. Occurrence of currently used pesticides in ambient air of Centre Region (France)

    NASA Astrophysics Data System (ADS)

    Coscollà, Clara; Colin, Patrice; Yahyaoui, Abderrazak; Petrique, Olivier; Yusà, Vicent; Mellouki, Abdelwahid; Pastor, Agustin

    2010-10-01

    Ambient air samples were collected, from 2006 to 2008 at three rural and two urban sites in Centre Region (France) and analyzed for 56 currently used pesticides (CUPs), of which 41 were detected. The four CUPs most frequently detected were the herbicides trifluralin, acetochlor and pendimethalin and the fungicide chlorothalonil, which were found with frequencies ranging between 52 and 78%, and with average concentrations of 1.93, 1.32, 1.84 and 12.15 ng m -3, respectively. Among the detected pesticides, concentrations of eight fungicides (spiroxamine, fenpropimorph, cyprodinil, tolyfluanid, epoxiconazole, vinchlozolin, fluazinam, fludioxinil), two insecticides (propargite, ethoprophos), and one herbicide (oxyfluorfen) are, to our knowledge, reported for the first time in the literature. The majority of the CUPs showed a seasonal trend, with most of the detections and the highest concentrations occurring during the spring and early summer. The most important pesticides detected were related to arable crops and fruit orchards, the main cultures in this region, highlighting the fact that the main sources come from local applications. Minor differences were found in the profiles of pesticides within rural areas and between rural and urban areas.

  2. Trends and abrupt changes in 104 years of ice cover and water temperature in a dimictic lake in response to air temperature, wind speed, and water clarity drivers

    NASA Astrophysics Data System (ADS)

    Magee, Madeline R.; Wu, Chin H.; Robertson, Dale M.; Lathrop, Richard C.; Hamilton, David P.

    2016-05-01

    The one-dimensional hydrodynamic ice model, DYRESM-WQ-I, was modified to simulate ice cover and thermal structure of dimictic Lake Mendota, Wisconsin, USA, over a continuous 104-year period (1911-2014). The model results were then used to examine the drivers of changes in ice cover and water temperature, focusing on the responses to shifts in air temperature, wind speed, and water clarity at multiyear timescales. Observations of the drivers include a change in the trend of warming air temperatures from 0.081 °C per decade before 1981 to 0.334 °C per decade thereafter, as well as a shift in mean wind speed from 4.44 m s-1 before 1994 to 3.74 m s-1 thereafter. Observations show that Lake Mendota has experienced significant changes in ice cover: later ice-on date(9.0 days later per century), earlier ice-off date (12.3 days per century), decreasing ice cover duration (21.3 days per century), while model simulations indicate a change in maximum ice thickness (12.7 cm decrease per century). Model simulations also show changes in the lake thermal regime of earlier stratification onset (12.3 days per century), later fall turnover (14.6 days per century), longer stratification duration (26.8 days per century), and decreasing summer hypolimnetic temperatures (-1.4 °C per century). Correlation analysis of lake variables and driving variables revealed ice cover variables, stratification onset, epilimnetic temperature, and hypolimnetic temperature were most closely correlated with air temperature, whereas freeze-over water temperature, hypolimnetic heating, and fall turnover date were more closely correlated with wind speed. Each lake variable (i.e., ice-on and ice-off dates, ice cover duration, maximum ice thickness, freeze-over water temperature, stratification onset, fall turnover date, stratification duration, epilimnion temperature, hypolimnion temperature, and hypolimnetic heating) was averaged for the three periods (1911-1980, 1981-1993, and 1994-2014) delineated by

  3. Combinative application of pH-zone-refining and conventional high-speed counter-current chromatography for preparative separation of caged polyprenylated xanthones from gamboge.

    PubMed

    Xu, Min; Fu, Wenwei; Zhang, Baojun; Tan, Hongsheng; Xiu, Yanfeng; Xu, Hongxi

    2016-02-01

    An efficient method for the preparative separation of four structurally similar caged xanthones from the crude extracts of gamboge was established, which involves the combination of pH-zone-refining counter-current chromatography and conventional high-speed counter-current chromatography for the first time. pH-zone-refining counter-current chromatography was performed with the solvent system composed of n-hexane/ethyl acetate/methanol/water (7:3:8:2, v/v/v/v), where 0.1% trifluoroacetic acid was added to the upper organic stationary phase as a retainer and 0.03% triethylamine was added to the aqueous mobile phase as an eluter. From 3.157 g of the crude extract, 1.134 g of gambogic acid, 180.5 mg of gambogenic acid and 572.9 mg of a mixture of two other caged polyprenylated xanthones were obtained. The mixture was further separated by conventional high-speed counter-current chromatography with a solvent system composed of n-hexane/ethyl acetate/methanol/water (5:5:10:5, v/v/v/v) and n-hexane/methyl tert-butyl ether/acetonitrile/water (8:2:6:4,v/v/v/v), yielding 11.6 mg of isogambogenic acid and 10.4 mg of β-morellic acid from 218.0 mg of the mixture, respectively. The purities of all four of the compounds were over 95%, as determined by high-performance liquid chromatography, and the chemical structures of the four compounds were confirmed by electrospray ionization mass spectrometry and NMR spectroscopy. The combinative application of pH-zone-refining counter-current chromatography and conventional high-speed counter-current chromatography shows great advantages in isolating and enriching the caged polyprenylated xanthones.

  4. Air quality assessment and management: Local and regional issues. Current issue paper number 23

    SciTech Connect

    Yeager, L.

    1998-12-31

    This paper provides and overview of the assessment and management of air quality in Ontario, with an emphasis on local and regional air quality rather than continental or global concerns such as acid rain and long-range transport of contaminants. It outlines some of the ways in which air quality is monitored in the province and describes some policy issues identified by experts and stakeholders. Sections of the paper cover the following: Ambient air quality monitoring; control of vehicle emissions; regulation and monitoring of industrial emissions; and the incorporation of local airshed management units in provincial regulations.

  5. Growth and characterization of high current density, high-speed InAs/AlSb resonant tunneling diodes

    NASA Technical Reports Server (NTRS)

    Soderstrom, J. R.; Brown, E. R.; Parker, C. D.; Mahoney, L. J.; Yao, J. Y.

    1991-01-01

    InAs/AlSb double-barrier resonant tunneling diodes with peak current densities up to 370,000 A/sq cm and high peak-to-valley current ratios of 3.2 at room temperature have been fabricated. The peak current density is well-explained by a stationary-state transport model with the two-band envelope function approximation. The valley current density predicted by this model is less than the experimental value by a factor that is typical of the discrepancy found in other double-barrier structures. It is concluded that threading dislocations are largely inactive in the resonant tunneling process.

  6. Indoor air quality: Carbon monoxide, molds and beyond. Current issue paper number 198

    SciTech Connect

    Yeager, L.

    1999-09-01

    This paper provides an overview of several of the major indoor air pollutants and some of the ways in which indoor air quality is addressed by governments in the United States and Canada. The emphasis is on non-industrial settings. Pollutants discussed include carbon dioxide, tobacco smoke, radon, carbon monoxide, nitrogen dioxide, wood smoke and particles, volatile organic compounds, and molds.

  7. Current State of the Evidence: Air Pollution Impacts on Human Health

    EPA Science Inventory

    Epidemiologic studies have demonstrated a consistent association between ambient levels of air pollution and adverse human health effects, including mortality and morbidity. Many of these studies have relied on the US Air Quality System (AQS) for exposure assessment. The AQS is a...

  8. Impacts of Particulate Air Pollution on Asthma: Current Understanding and Future Perspectives.

    PubMed

    Takizawa, Hajime

    2015-01-01

    The impacts of air pollution on human health and disease have been attracting attention, especially in industrialized countries and areas with heavy traffic burdens. Fine particulate matters (PMs) are considered as an important air pollutant, since it was reported that there was a significant relationship between PM2.5 levels and mortality by cohort studies in 1990s. Epidemiological and toxicological studies have strongly suggested a causative relationship between fine particulate air pollution and increased incidence as well as exacerbations of asthma, and other respiratory disorders. Recent advances in research have elucidated that PMs primarily and secondarily induce oxidative stresses which result both in pro- and antiinflammatory activities. It has been demonstrated that gene polymorphisms of antioxidant enzymes might change responses to particulate air pollution exposures. To prevent health hazardous effects of particles, it is crucial to screen susceptible subpopulations and establish chemoprevention strategies in the world. Novel techniques and modalities are patented for future progress on better control of air pollution.

  9. Variable Speed Wind Power Generation System Using Direct Torque Control Suited for Maximum Power Control within Voltage and Current Limitations of Converter

    NASA Astrophysics Data System (ADS)

    Inoue, Yukinori; Morimoto, Shigeo; Sanada, Masayuki

    This paper proposes a variable speed wind generation system using a direct torque controlled interior permanent magnet synchronous generator. The proposed system has no wind speed and generator position sensors, and thus, it is considered that the proposed system has cost and reliability advantages. The proposed direct torque control (DTC) system in wind power generation has several advantages over conventional current control. First, DTC is well suited for the maximum power point tracking (MPPT) control that is implemented by controlling the generator torque. Second, the method of flux-weakening to maintain the terminal voltage at the limiting value of the converter is simple. Finally, a novel method is proposed for torque limiting, which makes it easy to maintain the armature current at the limiting value. The proposed method accomplishes current limiting using the reactive torque, which is calculated as the inner product of the flux and current. This does not require generator parameters such as magnet flux and inductances. Experimental results demonstrate the effectiveness of the proposed system using a wind turbine emulator instead of the actual wind turbine.

  10. Occurrence and persistence of air stagnation events in current and future forcing regimes

    NASA Astrophysics Data System (ADS)

    Horton, D. E.; Diffenbaugh, N. S.

    2013-12-01

    Efforts to improve air quality often focus on reducing anthropogenic emissions of particulate matter, ozone, and/or the precursors of ozone. While such efforts are of primary importance, an additional, yet less frequently considered factor integral to air quality improvement, is the role that changing climate will play on the meteorological conditions associated with hazardous air quality and how such changes may modify the benefits of emission reductions. Here, we focus on the meteorological conditions that result in air stagnation, i.e., the atmospheric conditions that allow ozone and particulate matter to accumulate and persist in the near-surface environment. We examine the occurrence and persistence of air stagnation events using a suite of late-20th and early-21st century reanalysis datasets as well as an ensemble of bias-corrected historic and future global climate projections. To quantify air stagnation events, we apply a National Climatic Data Center (NCDC) metric that tracks the co-occurrence of days with light upper level winds, light lower level winds, and no precipitation; termed the Air Stagnation Index (ASI). Daily-scale air stagnation occurrence and persistence in the reanalysis data sets are compared to an ensemble of bias-corrected Coupled Model Intercomparison Project (CMIP5) historic and future realizations. Preliminary examinations suggest that bias corrected historic CMIP5 simulations capture both the occurrence frequency and persistence of reanalysis-observed air stagnation, while future increases in the frequency of stagnation day occurrence are highest in eastern China, Mediterranean Europe, and the southeastern United States. We discuss the different NCDC ASI parameter dependencies in these regions and examine the role of global warming on their meteorological shifts.

  11. High speed domain wall motion in MgO-based magnetic tunnel junctions driven by perpendicular current injection

    NASA Astrophysics Data System (ADS)

    Metaxas, P. J.; Chanthbouala, A.; Matsumoto, R.; Cros, V.; Anane, A.; Grollier, J.; Fert, A.; Zvezdin, K. A.; Fukushima, A.; Yuasa, S.

    2012-02-01

    The ability to efficiently drive fast domain wall (DW) motion will pave the way for revolutionary new electronic devices ranging from DW-MRAMs to spintronic memristors. The majority of domain wall devices use a lateral, current-in-plane configuration in which critical current densities for domain wall motion remain quite high, typically being on the order of 100 MA/cm^2 with velocities generally limited to about 100 m/s. In this contribution we show that critical current densities can be decreased by up to two orders of magnitude using the current-perpendicular-to-plane geometry. Indeed, we demonstrate that a DW can be propagated back and forth along the free layer of a MgO-based magnetic tunnel junction (MTJ) in the absence of an external magnetic field using current densities that are on the order of 5 MA/cm^2. More notably however, we obtain high domain wall velocities for these low current densities: the MTJ's large resistance variations allow us to carry out time-resolved measurements of the wall motion from which we evidence DW velocities exceeding 500m/s.

  12. Effects of atmospheric air plasma treatment of graphite and carbon felt electrodes on the anodic current from Shewanella attached cells.

    PubMed

    Epifanio, Monica; Inguva, Saikumar; Kitching, Michael; Mosnier, Jean-Paul; Marsili, Enrico

    2015-12-01

    The attachment of electrochemically active microorganisms (EAM) on an electrode is determined by both the chemistry and topography of the electrode surface. Pre-treatment of the electrode surface by atmospheric air plasma introduces hydrophilic functional groups, thereby increasing cell attachment and electroactivity in short-term experiments. In this study, we use graphite and carbon felt electrodes to grow the model EAM Shewanella loihica PV-4 at oxidative potential (0.2 V vs. Ag/AgCl). Cell attachment and electroactivity are measured through electrodynamic methods. Atmospheric air plasma pre-treatment increases cell attachment and current output at graphite electrodes by 25%, while it improves the electroactivity of the carbon felt electrodes by 450%. Air plasma pre-treatment decreased the coulombic efficiency on both carbon felt and graphite electrodes by 60% and 80%, respectively. Microbially produced flavins adsorb preferentially at the graphite electrode, and air plasma pre-treatment results in lower flavin adsorption at both graphite and carbon felt electrodes. Results show that air plasma pre-treatment is a feasible option to increase current output in bioelectrochemical systems.

  13. Low-noise and high-speed photodetection system using optical feedback with a current amplification function.

    PubMed

    Akiba, M

    2015-09-01

    A photodetection system with an optical-feedback circuit accompanied by current amplification was fabricated to minimize the drawbacks associated with a transimpedance amplifier (TIA) with a very high resistance feedback resistor. Current amplification was implemented by extracting an output light from the same light source that emitted the feedback light. The current gain corresponds to the ratio of the photocurrent created by the output light to that created by the feedback light because the feedback current value is identical to the input photocurrent value generated by an input light to be measured. The current gain has no theoretical limit. The output light was detected by a photodiode with a TIA having a small feedback resistance. The expression for the input-referred noise current of the optical-feedback photodetection system was derived, and the trade-off between sensitivity and response, which is a characteristic of TIA, was found to considerably improve. An optical-feedback photodetection system with an InGaAs pin photodiode was fabricated. The measured noise equivalent power of the system was 1.7 fW/Hz(1/2) at 10 Hz and 1.3 μm, which is consistent with the derived expression. The time response of the system was found to deteriorate with decreasing photocurrent. The 50% rise time for a light pulse input increased from 3.1 μs at a photocurrent of 10 nA to 15 μs at photocurrents below 10 pA. The bandwidth of the input-referred noise current was 7 kHz, which is consistent with rise times below 10 pA. PMID:26429465

  14. Exposure information in environmental health research: Current opportunities and future directions for particulate matter, ozone, and toxic air pollutants

    SciTech Connect

    McKone, Thomas E.; Ryan, P. Barry; Ozkaynak, Haluk

    2007-02-01

    Understanding and quantifying outdoor and indoor sources of human exposure are essential but often not adequately addressed in health-effects studies for air pollution. Air pollution epidemiology, risk assessment, health tracking and accountability assessments are examples of health-effects studies that require but often lack adequate exposure information. Recent advances in exposure modeling along with better information on time-activity and exposure factors data provide us with unique opportunities to improve the assignment of exposures for both future and ongoing studies linking air pollution to health impacts. In September 2006, scientists from the US Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention (CDC) along with scientists from the academic community and state health departments convened a symposium on air pollution exposure and health in order to identify, evaluate, and improve current approaches for linking air pollution exposures to disease. This manuscript presents the key issues, challenges and recommendations identified by the exposure working group, who used cases studies of particulate matter, ozone, and toxic air pollutant exposure to evaluate health-effects for air pollution. One of the over-arching lessons of this workshop is that obtaining better exposure information for these different health-effects studies requires both goal-setting for what is needed and mapping out the transition pathway from current capabilities to meeting these goals. Meeting our long-term goals requires definition of incremental steps that provide useful information for the interim and move us toward our long-term goals. Another over-arching theme among the three different pollutants and the different health study approaches is the need for integration among alternate exposure assessment approaches. For example, different groups may advocate exposure indicators, biomonitoring, mapping methods (GIS), modeling, environmental media

  15. Integrating Sensor Monitoring Technology into the Current Air Pollution Regulatory Support Paradigm: Practical Considerations

    EPA Science Inventory

    The US Environmental Protection Agency (EPA) along with state, local, and tribal governments operate Federal Reference Method (FRM) and Federal Equivalent Method (FEM) instruments to assess compliance with US air pollution standards designed to protect human and ecosystem health....

  16. An improved design of spiral tube assembly for separation of proteins by high-speed counter-current chromatography.

    PubMed

    Dasarathy, Dhweeja; Ito, Yoichiro

    2015-10-30

    A new spiral tube assembly was designed to improve the column capacity and partition efficiency for protein separation. This spiral tube assembly has greater column capacity than the original tubing because of an increase in radial grooves from 4 to 12 to accommodate more spiral layers and 12 narrow spots instead of 4 in each circular loop to interrupt the laminar flow that causes sample band broadening. Standard PTFE tubing (1.6mm ID) and the modified flat-twisted tubing were used as the separation column. The performances of both assemblies were compared for separating three stable test proteins including cytochrome c, myoglobin, and lysozyme using a two phase aqueous-aqueous solvent system composed of polyethylene glycol 1000 (12.5% w/w) and dibasic potassium phosphate (12.5% w/w). All samples were run at 1, 2, 3, and 5mL/min at both 800rpm and 1000rpm. The separation of these three protein samples produced high stationary phase retentions at 1, 2, and 3mL/min, yet separated efficiently at 5mL/min in 40min. After comparing the separation efficiency in terms of the peak resolutions, theoretical plate numbers, and separation times, it was determined that the flat-twisted tubing was more effective in separating these protein samples. In order to validate the efficacy of this novel assembly, a mixture of five protein samples (cytochrome c, myoglobin, ovalbumin, lysozyme, and hemoglobin) were separated, under the optimal conditions established with these three protein samples, at 1mL/min with a revolution speed of 1000rpm. There were high stationary phase retentions of around 60%, with effective separations, demonstrating the efficiency of the flat-twisted spiral tube assembly. The separation time of 6h was a limitation but can potentially be shortened by improving the strength of the column that will permit an increase in revolution speed and flow rate. This novel spiral separation column will allow rapid and efficient separation of mixtures with high yield of the

  17. The relationship between the microwave radar cross section and both wind speed and stress: Model function studies using Frontal Air-Sea Interaction Experiment data

    NASA Technical Reports Server (NTRS)

    Weissman, David E.; Davidson, Kenneth L.; Brown, Robert A.; Friehe, Carl A.; Li, Fuk

    1994-01-01

    The Frontal Air-Sea Interaction Experiment (FASINEX) provided a unique data set with coincident airborne scatterometer measurements of the ocean surface radar cross section (RCS)(at Ku band) and near-surface wind and wind stress. These data have been analyzed to study new model functions which relate wind speed and surface friction velocity (square root of the kinematic wind stress) to the radar cross section and to better understand the processes in the boundary layer that have a strong influence on the radar backscatter. Studies of data from FASINEX indicate that the RCS has a different relation to the friction velocity than to the wind speed. The difference between the RCS models using these two variables depends on the polarization and the incidence angle. The radar data have been acquired from the Jet Propulsion Laboratory airborne scatterometer. These data span 10 different flight days. Stress measurements were inferred from shipboard instruments and from aircraft flying at low altitudes, closely following the scatterometer. Wide ranges of radar incidence angles and environmental conditions needed to fully develop algorithms are available from this experiment.

  18. Rapid preparative separation of six bioactive compounds from Gentiana crassicaulis Duthie ex Burk. using microwave-assisted extraction coupled with high-speed counter-current chromatography

    PubMed Central

    Liang, Jinru; Ito, Yoichiro; Zhang, Xinxin; He, Jiao; Sun, Wenji

    2014-01-01

    A rapid method combining microwave-assisted extraction and high-speed counter-current chromatography was applied for preparative separation of six bioactive compounds including loganic acid (I), isoorientin-4'-O-glucoside (II), 6'-O-β-d-glucopyranosyl gentiopicroside (III), swertiamarin (IV), gentiopicroside (V), sweroside (VI) from traditional Tibetan medicine Gentiana crassicaulis Duthie ex Burk. Microwave-assisted extraction parameters were predicted by central composite design-response surface methodology. That is, 5.0 g dried roots of G. Crassicaulis was extracted with 50 mL 57.5% aqueous ethanol under 630 W for 3.39 min. The extract (gentian total glycosides) was separated by high-speed counter-current chromatography with n-butanol/ethyl acetate/methanol/1% acetic acid water (7.5:0.5:0.5:3.5, v/v/v/v) using upper phase mobile in tail-to-head elution mode. 16.3 mg, 8.8 mg, 12.8 mg, 25.1 mg, 40.7 mg and 21.8 mg of compounds I–VI were obtained with high purities in one run from 500 mg of original sample. The purities and identities of separated components were confirmed using HPCL with photo diode array detection and quadrupole time-of-flight MS and NMR spectroscopy. The study reveals that response surface methodology is convenient and highly predictive for optimizing extraction process, microwave-assisted extraction coupled with high-speed counter-current chromatography could be an expeditious method for extraction and separation of phytochemicals from ethnomedicine. PMID:24151213

  19. Isolation of chavibetol from essential oil of Pimenta pseudocaryophyllus leaf by high-speed counter-current chromatography.

    PubMed

    dos Santos, Bruna C B; da Silva, Júlio César T; Guerrero, Palimécio G; Leitão, Gilda G; Barata, Lauro E S

    2009-05-01

    Counter-current chromatography (CCC) was used to isolate chavibetol from the essential oil of leaves of Pimenta pseudocaryophyllus (Gomes) Landrum. Chavibetol was obtained in high purity (98%) and mass recovery (94.4%). Methyleugenol was also isolated. The CCC biphasic solvent system used was composed of hexane:n-butanol:methanol:water (12:4:4:3, v/v/v/v).

  20. Large-scale isolation and purification of geniposide from the fruit of Gardenia jasminoides Ellis by high-speed counter-current chromatography.

    PubMed

    Zhou, Tingting; Fan, Guorong; Hong, Zhanying; Chai, Yifeng; Wu, Yutian

    2005-12-23

    High-speed counter-current chromatography (HSCCC) was applied to the isolation and purification of geniposide from Gardenia jasminoides Ellis. Analytical HSCCC was used for the preliminary selection of a suitable solvent system composed of ethyl acetate-n-butanol-water (2:1:3, v/v/v). According to the above solvent system, preparative HSCCC was successfully performed with the optimal solvent system composed of ethyl acetate-n-butanol-water (2:1.5:3, v/v/v) yielding 389 mg of geniposide at over 98% purity from 1g of the partially purified extract with 38.9% recovery in a one-step separation.

  1. Review of current and anticipated regulations on air protection in the Czech Republic

    SciTech Connect

    Jilek, P.; Novotny, V.

    1995-12-01

    Environmental issues, especially the solution of the air pollution problem, have taken on great significance in the Czech Republic (which was a part of the Czech and Slovak Federal Republic until the end of 1992) since the 1989 {open_quotes}Velvet{close_quotes} Revolution. The former CSFR Federal Committee for the Environment and both the Republic Ministries started immediately with creating new environmental legislation, which is the main governmental tool for protecting the environment in the newly developing democracy state system with a market oriented economy. The inspiration for that activity was found in legislation of developed countries - member states of the European Union, and in German environmental law in particular. This paper surveys the major laws and regulations that gradually came into force in the Czech Republic since 1990. The provisions of the primary significance are the Act No.309/1991 S.B., dated July 9, 1991, on the protection of the air against pollutants - The Clean Air Act, the Act No.218/1992 S.B., dated April 27, 1992, which changes and supplements the Act No.309 - The Clean Air Act, the Measure of the Federal Committee for the Environment of October 1, 1991 to the Clean Air Act, and its amended wordings of June 23, 1992, 84/1991 S.B., and 84/1992 S.B., the Act No.389/1991 S.B., dated September 10, 1991 on the state administration of air protection and charges for the pollution of air, and several regulations based on the Act No.389/1991 S.B., issued in the period 1992 -1993.

  2. Separation of nine compounds from Salvia plebeia R.Br. using two-step high-speed counter-current chromatography with different elution modes.

    PubMed

    Ren, Da-Bing; Qin, Yan-Hua; Yun, Yong-Huan; Lu, Hong-Mei; Chen, Xiao-Qing; Liang, Yi-Zeng

    2014-08-01

    Nine compounds were successfully separated from Salvia plebeia R.Br. using two-step high-speed counter-current chromatography with three elution modes. Elution-extrusion counter-current chromatography was applied in the first step, while classical counter-current chromatography and recycling counter-current chromatography were used in the second step. Three solvent systems, n-hexane/ethyl acetate/ethanol/water (4:6.5:3:7, v/v), methyl tert-butyl ether/ethyl acetate/n-butanol/methanol/water (6:4:1:2:8, v/v) and n-hexane/ethyl acetate/methanol/water (5:5.5:5:5, v/v) were screened and optimized for the two-step separation. The separation yielded nine compounds, including caffeic acid (1), 6-hydroxyluteuolin-7-glucoside (2), 5,7,3',4'-tetrahydroxy-6-methoxyflavanone-7-glucoside (3), nepitrin (4), rosmarinic acid (5), homoplantaginin (6), nepetin (7), hispidulin (8), and 5,6,7,4'-tertrahydroxyflavone (9). To the best of our knowledge, 5,7,3',4'-tetrahydroxy-6-methoxyflavanone-7-glucoside and 5,6,7,4'-tertrahydroxyflavone have been separated from Salvia plebeia R.Br. for the first time. The purities and structures of these compounds were identified by high-performance liquid chromatography, electrospray ionization mass spectrometry, (1)H and (13)C NMR spectroscopy. This study demonstrates that high-speed counter-current chromatography is a useful and flexible tool for the separation of components from a complex sample.

  3. Current status of the development of the refuelable aluminum-air battery

    SciTech Connect

    Cooper, J.F.; Kraftick, K.K.; McKinley, B.J.

    1983-08-01

    This report reviews the technical status of a refuelable aluminum-air battery using flowing caustic-aluminate electrolyte at 50-70/sup 0/C. Four distinct designs for rapidly-refuelable cells were evaluated in single or multicell modules on an engineering scale (167-1000 cm/sup 2//cell). Consideration is given to cells of the wedge configuration, which allow partial recharge, high anode utilization, and rapid refueling. Kinetic models developed for aluminum trihydroxide precipitation are used to predict the behavior of integrated cell/crystallizer systems. Drive-cycle life and polarization data are reviewed for air-electrodes under simulated vehicle operating conditions. Problems in the development of cost-effective anode alloys are described. These results are interpreted from the perspective of the potential of an aluminum-air battery to provide an electric vehicle with the range, acceleration and rapid-refueling capabilities of common automobiles.

  4. Current status of the development of the refuelable aluminum-air battery

    SciTech Connect

    Cooper, J.F.; Kraftick, K.A.; McKinley, B.J.

    1983-05-10

    This report reviews the technical status of a refuelable aluminum-air battery using flowing caustic-aluminate electrolyte at 50 to 70/sup 0/C. Four distinct designs for rapidly-refuelable cells were evaluated in single or multicell modules on an engineering scale (167 to 1000 cm/sup 2//cell). Consideration is given to cells of the wedge configuration, which allow partial recharge, high anode utilization, and rapid refueling. Kinetic models developed for aluminum trihydroxide precipitation are used to predict the behavior of integrated cell/crystallizer systems. Drive-cycle life and polarization data are reviewed for air-electrodes under simulated vehicle operating conditions. Problems in the development of cost-effective anode alloys are described. These results are interpreted from the perspective of the potential of an aluminum-air battery to provide an elecric vehicle with the range, acceleration and rapid-refueling capabilities of common automobiles.

  5. Aseptic necrosis in compressed air tunnel workers using current OSHA decompression schedules.

    PubMed

    Kindwall, E P; Nellen, J R; Spiegelhoff, D R

    1982-10-01

    Aseptic necrosis (dysbaric osteonecrosis) was discovered in two compressed air tunnel workers who had used the present Occupational Health and Safety Administration (OSHA) decompression tables for compressed air tunneling at pressures greater than 36 pounds per square inch gauge (psig). A roentgenographic study was made of 21 men who had worked at pressures up to 43 psig using the OSHA schedules. Bone scanning was also included. Seven of the men (33%) were found to have aseptic necrosis involving the shoulders, hips or distal femoral shafts and proximal tibia. It became evident that the present OSHA schedules caused not only an unacceptable incidence of decompression sickness but also aseptic necrosis at pressures over 36 psig. New interim tables that are more conservative and that use either air or oxygen as a breathing gas during decompression are undergoing laboratory and worksite evaluation.

  6. Enrichment and separation of antitumor triterpene acids from the epidermis of Poria cocos by pH-zone-refining counter-current chromatography and conventional high-speed counter-current chromatography.

    PubMed

    Dong, Hongjing; Wu, Panpan; Yan, Renyi; Xu, Qihua; Li, Hua; Zhang, Fangbo; Li, Jianrong; Yang, Bin

    2015-06-01

    Triterpene acids were extracted from the epidermis of Poria cocos (Schw.) Wolf. These acids were found to inhibit the growth of lung cancer cells in vitro and in vivo. An efficient method for the preparative separation of antitumor triterpene acids was established that involves the combination of pH-zone-refining counter-current chromatography and conventional high-speed counter-current chromatography. We used pH-zone-refining counter-current chromatography to concentrate the triterpene acids using a two-phase solvent system composed of petroleum ether/ethyl acetate/methanol/water (3:7:5:5, v/v/v/v), trifluoroacetic acid (10 mM) was added to the upper phase as a retainer, and ammonia (10 mM) was added to the lower phase as an eluter. As a result, 200 mg concentrate of triterpene acids was obtained from 1.0 g of crude extract. The concentrate was further separated by conventional high-speed counter-current chromatography using a solvent system composed of petroleum ether/ethyl acetate/methanol/water (0.8:1.2:1.2:0.9, v/v), yielding 50 mg of poricoic acid A and 5 mg of poricoic acid B from 120 mg concentrate, respectively. The inhibitory activity of the major compound on lung A549 cells was examined and poricoic acid A was found to significantly inhibit the growth of A 549 cells.

  7. Enrichment and separation of antitumor triterpene acids from the epidermis of Poria cocos by pH-zone-refining counter-current chromatography and conventional high-speed counter-current chromatography.

    PubMed

    Dong, Hongjing; Wu, Panpan; Yan, Renyi; Xu, Qihua; Li, Hua; Zhang, Fangbo; Li, Jianrong; Yang, Bin

    2015-06-01

    Triterpene acids were extracted from the epidermis of Poria cocos (Schw.) Wolf. These acids were found to inhibit the growth of lung cancer cells in vitro and in vivo. An efficient method for the preparative separation of antitumor triterpene acids was established that involves the combination of pH-zone-refining counter-current chromatography and conventional high-speed counter-current chromatography. We used pH-zone-refining counter-current chromatography to concentrate the triterpene acids using a two-phase solvent system composed of petroleum ether/ethyl acetate/methanol/water (3:7:5:5, v/v/v/v), trifluoroacetic acid (10 mM) was added to the upper phase as a retainer, and ammonia (10 mM) was added to the lower phase as an eluter. As a result, 200 mg concentrate of triterpene acids was obtained from 1.0 g of crude extract. The concentrate was further separated by conventional high-speed counter-current chromatography using a solvent system composed of petroleum ether/ethyl acetate/methanol/water (0.8:1.2:1.2:0.9, v/v), yielding 50 mg of poricoic acid A and 5 mg of poricoic acid B from 120 mg concentrate, respectively. The inhibitory activity of the major compound on lung A549 cells was examined and poricoic acid A was found to significantly inhibit the growth of A 549 cells. PMID:25821060

  8. High-speed analysis of complex indoor VOC mixtures by vacuum-outlet GC with air carrier gas and programmable retention.

    PubMed

    Grall, A J; Zellers, E T; Sacks, R D

    2001-01-01

    A pressure-tunable, series-coupled column ensemble was used with atmospheric pressure air as carrier gas for the vacuum-outlet GC analysis of 42 volatile and semivolatile organic compounds commonly encountered as indoor air pollutants. Separation strategies applicable to a field-portable instrument that will employ a dual-stage preconcentrator and a microsensor array as the detector were developed, where coelution of certain analytes can be tolerated. The capillary column ensemble consists of a 4.5-m segment of nonpolar dimethyl polysiloxane followed by a 7.5-m segment of polar trifluoropropylmethyl polysiloxane. Good long-term thermal stability of the column ensemble was observed for continuous operation in air at temperatures up to 210 degrees C. A computer-driven pressure controller at the column junction point is used to adjust vapor retention for specified sets of target compounds. The compounds were divided into two groups according to retention order, and high-speed analysis conditions were determined for the two groups individually as well as for the entire mixture. The earlier eluting group of 21 compounds was analyzed isothermally at 30 degrees C in about 160 s using a single, on-the-fly junction-point pressure change during the separation. The later eluting group of 21 compounds was analyzed in about 200 s with temperature programming and a constant (tuned) junction-point pressure. The entire mixture was analyzed in about 400 s using a two-step temperature program and a three-step pressure program, with minimal overlap in eluting peaks. Separations are adequate for analysis by a sensor array capable of discriminating among small groups of coeluting vapors on the basis of their response patterns.

  9. Electrical performance characterisation of single-shot switches in high speed, high voltage and high current applications

    NASA Astrophysics Data System (ADS)

    Podlesak, Michael

    1994-08-01

    The electrical performance characteristics of single-shot closing switches for slapper detonator applications were measured via the discharge of a low impedance transmission line. The switch performance, characterized by its time-dependent resistance behavior, could not be assessed via the more conventional methods of measurement because of high bandwidth requirements at comparatively high levels of voltage and current. Hence, an alternative technique based on a transmission line discharge was devised in which the time-dependent resistance of the switch can be determined from the measured current waveform of the switch, the initial open circuit voltage and the transmission line parameters only. Under certain conditions a simple lossless transmission line formula is sufficient for the calculation of the switch resistance waveform. However, if the transmission line losses cannot be neglected, a correction can be readily implemented through numerical signal processing. The bandwidth of this technique is limited to the bandwidth of the switch current measurement only, which proved to be particularly useful for the measurement of switches for slapper detonator applications where inductive pick-up noise in the switch voltage waveform is large and where high voltage probes of sufficiently high bandwidth are not readily available. In this report, both numerically simulated and experimental examples are given, together with the method of calculation of switch resistance which takes into account practical transmission line losses. It was found that best results are obtained if the magnitude of the switch resistance is of a similar order as the characteristic impedance of the transmission line, or higher.

  10. Stack optimization of oxide-based RRAM for fast write speed (<1 μs) at low operating current (<10 μA)

    NASA Astrophysics Data System (ADS)

    Chen, C. Y.; Goux, L.; Fantini, A.; Degraeve, R.; Redolfi, A.; Groeseneken, G.; Jurczak, M.

    2016-11-01

    In this paper we engineer a TiN ⧹ Al2O3 ⧹ (Hf,Al)O2 ⧹ Ta2O5 ⧹ Hf Oxide Resistive Random Access Memory (OxRRAM) device for fast switching at low operation current without sacrificing the retention and endurance properties. The integrated 40 nm × 40 nm cell switches at 10 μA using write pulses shorter than 100 ns (resp. 1 μs) for Reset (resp. Set) and with amplitude <2 V. Using these conditions in a specially developed verify algorithm, a resistive window of 10× is reliably obtained, decreasing the write speed by more than 1 decade compared to state-of-the-art OxRRAM stacks at same current level.

  11. Three-phase solvent systems for the comprehensive separation of a wide variety of compounds from Dicranostigma leptopodum by high-speed counter-current chromatography.

    PubMed

    Liu, Yanjuan; Chen, Xiaofen; Liu, JunXi; Di, Duolong

    2015-06-01

    A three-phase solvent system was efficiently applied for high-speed counter-current chromatography to separate secondary metabolites with a wide range of hydrophobicity in Dicranostigma leptopodum. The three-phase solvent system of n-hexane/methyl tert-butyl ether/acetonitrile/0.5% triethylamine (2:2:3:2, v/v/v/v) was selected for high-speed counter-current chromatography separation. The separation was initiated by filling the column with a mixture of intermediate phase and lower phase as a stationary phase followed by elution with upper phase to separate the hydrophobic compounds. Then the mobile phase was switched to the intermediate phase to elute the moderately hydrophobic compounds, and finally the polar compounds still retained in the column were fractionated by eluting the column with the lower phase. In this research, 12 peaks were eluted out in one-step operation within 110 min, among them, eight compounds with acceptable purity were obtained and identified. The purities of β-sitosterol, protopine, allocryptopine, isocorydione, isocorydine, coptisine, berberrubine, and berberine were 94.7, 96.5, 97.9, 86.6, 98.9, 97.6, 95.7, and 92.8%, respectively.

  12. Preparative separation of bioactive compounds from essential oil of Flaveria bidentis (L.) Kuntze using steam distillation extraction and one step high-speed counter-current chromatography.

    PubMed

    Wei, Yun; Du, Jilin; Lu, Yuanyuan

    2012-10-01

    In order to utilize and control the invasive weed, bioactive compounds from essential oil of Flaveria bidentis (L.) Kuntze were studied. Steam distillation extraction and one step high-speed counter-current chromatography were applied to separate and purify the caryophyllene oxide, 7,11-dimethyl-3-methylene-1,6,10-dodecatriene, and caryophyllene from essential oil of Flaveria bidentis (L.) Kuntze. The two-phase solvent system containing n-hexane/acetonitrile/ethanol (5:4:3, v/v/v) was selected for the one step separation mode according to the partition coefficient values (K) of the target compounds and the separation factor (α). The purity of each isolated fraction after a single high-speed counter-current chromatography run was determined by high performance liquid chromatography. A 3.2 mg of caryophyllene oxide at a purity of 92.6%, 10.4 mg of 7,11-dimethyl-3-methylene-1,6,10-dodecatriene at a purity of 99.1% and 5.7 mg of caryophyllene at a purity of 98.8% were obtained from 200 mg essential oil of Flaveria bidentis (L.) Kuntze. The chemical structures of these components were identified by GC-MS, (1) H-NMR, and (13) C-NMR.

  13. The Importance of Exposure in Addressing Current and Emerging Air Quality Issues

    EPA Science Inventory

    The air quality issues that we face today and will face in the future are becoming increasingly more complex and require an improved understanding of human exposure to be effectively addressed. The objectives of this paper are (1) to discuss how concepts of human exposure and ex...

  14. [Current status of the control of the levels of harmful substances in the air of the work area during welding].

    PubMed

    Gorban', L N

    1991-01-01

    The article reveals the current issues pertaining to the improvement of control after hazardous substances contents in the welding working zone air. The welding aerosols are multicomponent and constitute a group of complex gas-aerosol mixtures,--the feature which requires a separate detection of the individual concentrations of the most hazardous components, both hard and gaseous. Data on the specific excretion of hazardous substances should be included in respective technical documentation relating to welding processes and materials. PMID:2055543

  15. Selected current-use and historic-use pesticides in air and seawater of the Bohai and Yellow Seas, China

    NASA Astrophysics Data System (ADS)

    Zhong, Guangcai; Tang, Jianhui; Xie, Zhiyong; Möller, Axel; Zhao, Zhen; Sturm, Renate; Chen, Yingjun; Tian, Chongguo; Pan, Xiaohui; Qin, Wei; Zhang, Gan; Ebinghaus, Ralf

    2014-01-01

    Consumption of pesticides in China has increased rapidly in recent years; however, occurrence and fate of current-use pesticides (CUPs) in China coastal waters are poorly understood. Globally banned pesticides, so-called historic-use pesticides (HUPs), are still commonly observed in the environment. In this work, air and surface seawater samples taken from the Bohai and Yellow Seas in May 2012 were analyzed for CUPs including trifluralin, quintozene, chlorothalonil, dicofol, chlorpyrifos, and dacthal, as well as HUPs (hexachlorobenzene (HCB), hexachlorocyclohexanes (HCHs), and endosulfan). CUP profile in both air and seawater samples generally reflected their consumption patterns in China. HUPs in the air and seawater samples were in comparable levels as those of CUPs with high concentrations. α-Endosulfan, dicofol, and chlorothalonil showed strong net deposition likely resulting from their intensive use in recent years, while CUPs with low consumption amount (quintozene and dacthal) were close to equilibrium at most samplings sites. Another CUP with high usage amout (i.e., chlorpyrifos) underwent volatilization possibly due to its longer half-life in seawater than that in air. α-HCH and γ-HCH were close to equilibrium in the Bohai Sea, but mainly underwent net deposition in the Yellow Sea. The net deposition of α-HCH could be attributed to polluted air pulses from the East China identified by air mass back trajectories. β-HCH showed net volatilization in the Bohai Sea, which was driven by its relative enrichment in seawater. HCB either slightly favored net volatilization or was close to equilibrium in the Bohai and Yellow Seas.

  16. Inactivation of Staphylococcus aureus and Enterococcus faecalis by a direct-current, cold atmospheric-pressure air plasma microjet☆

    PubMed Central

    Tian, Ye; Sun, Peng; Wu, Haiyan; Bai, Na; Wang, Ruixue; Zhu, Weidong; Zhang, Jue; Liu, Fuxiang

    2010-01-01

    Objective A direct-current, cold atmospheric-pressure air plasma microjet (PMJ) was performed to inactivate Staphylococcus aureus (S. aureus) and Enterococcus faecalis (E. faecalis) in air. The process of sterilization and morphology of bacteria was observed. We wish to know the possible inactivation mechanisms of PMJ and explore a potential application in dental and other temperature sensitive treatment. Methods In this study, we employed a direct current, atmospheric pressure, cold air PMJ to inactivate bacterias. Scanning electron microscopy was employed to evaluate the morphology of S. aureus and showed rupture of cell walls after the plasma treatment and Optical emission spectrum (OES) were used to understand the possible inactivation mechanisms of PMJ. Results The inactivation rates could reach 100% in 5 min. When the distance between the exit nozzle of the PMJ device and Petri dish was extended from 1 cm to 3 cm, effective inactivation was also observed with a similar inactivation curve. Conclusion The inactivation of bacteria is attributed to the abundant reactive oxygen and nitrogen species, as well as ultroviolet radiation in the plasma. Different life spans and defensibilities of these killing agents may hold the key to understanding the different inactivation curves at different treatment distances. PMID:23554639

  17. Effect of electrical current on the tribological behavior of the Cu-WS2-G composites in air and vacuum

    NASA Astrophysics Data System (ADS)

    Qian, Gang; Feng, Yi; Li, Bin; Huang, Shiyin; Liu, Hongjuan; Ding, Kewang

    2013-03-01

    As the traditional graphite-based composites cannot meet the requirement of rapid developing modern industry, novel sliding electrical contact materials with high self-lubricating performance in multiple environments are eagerly required. Herein a copper-based composite with WS2 and graphite as solid lubricant are fabricated by powder metallurgy hot-pressed method. The friction and wear behaviors of the composites with and without current are investigated under the condition with sliding velocity of 10 m/s and normal load of 2.5 N/cm2 in both air and vacuum. Morphologies of the worn surfaces are observed by optical microscope and compositions of the lubricating films are analyzed by XPS. Surface profile curves and roughness of the worn surfaces are obtained by 2205 surface profiler. The results of wear tests show that the friction coefficient and wear volume loss of the composites with current are greater than that without current in both air and vacuum due to the adverse effects of electrical current which damaged the lubricating film partially and roughed the worn surfaces. XPS results demonstrate that the lubricating film formed in air is composed of oxides of Cu, WS2, elemental S and graphite, while the lubricating film formed in vacuum is composed of Cu, WS2 and graphite. Because of the synergetic lubricating action of oxides of Cu, WS2 and graphite, the composites show low friction coefficient and wear volume loss in air condition. Owing to the fact that graphite loses its lubricity which makes WS2 become the only lubricant, severe adhesive and abrasive wear occur and result in a high value of wear rate in vacuum condition. The formation of the lubricating film on the contact interface between the brush and ring is one of the factors which can greatly affect the wear performance of the brushes. The low contact voltage drop of the composites in vacuum condition is attributed to the high content of Cu in the surface film. This study fabricated a kind of new

  18. Current Progresses of Midass: Microbial Detection in Air System for Space

    NASA Astrophysics Data System (ADS)

    Abaibou, Hafid; Lasseur, Christophe; Mabilat, Claude; Storrs-Mabilat, Michele; Guy, Michel; Raffestin, Stephanie; Sole Bosquet, Jaume

    For the long term manned missions, microbial contamination is a major risk for crew members and hardware. This risk has first been documented by Russian scientists then by other organizations as a consequence of the contamination of metabolic consumables (water, air), and also the hardware degradation. Rapid molecular biology techniques offer an attractive alternative to traditional culture-based methods. They allow fast time to results for contamination detection and quick implementation of appropriate corrective action when required. However, to date, there are no such available system due to the technical challenges required to meet the sensitivity and specificity needs of the test and the requirement for full automation, from sampling to results interpretation. In response to this, over the last decade, the European Space Agency (ESA) and bioMérieux initiated a co-development of MIDASS, the world’s first fully automated system for the monitoring of the environmental microbial load in confined spaces, including clean rooms and hospital wards. The system is based on molecular technologies (sample preparation/amplification/detection) and enables rapid and simple determination of the microbiological contamination level in less than 3 hours. It relies on NASBA-amplification for the detection of selected micro-organisms (indicators or pathogens) at determined risk-levels (200 and 1 CFU /m3 air, respectively). Successful progresses were recently made for the space-application workpackage of this project: a lab-on-a-card design for air-testing in a first scope was endorsed by a successful ESA Preliminary Design Review, paving the way to spatialization steps (phases C and D). Data will be presented with regards to system design and biological performances.

  19. Characteristics of a Direct Current-driven plasma jet operated in open air

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Di, Cong; Jia, Pengying; Bao, Wenting

    2013-09-01

    A DC-driven plasma jet has been developed to generate a diffuse plasma plume by blowing argon into the ambient air. The plasma plume, showing a cup shape with a diameter of several centimeters at a higher voltage, is a pulsed discharge despite a DC voltage is applied. The pulse frequency is investigated as a function of the voltage under different gap widths and gas flow rates. Results show that plasma bullets propagate from the hollow needle to the plate electrode by spatially resolved measurement. A supposition about non-electroneutral trail of the streamer is proposed to interpret these experimental phenomena.

  20. Characteristics of a Direct Current-driven plasma jet operated in open air

    SciTech Connect

    Li, Xuechen; Bao, Wenting; Di, Cong; Jia, Pengying

    2013-09-30

    A DC-driven plasma jet has been developed to generate a diffuse plasma plume by blowing argon into the ambient air. The plasma plume, showing a cup shape with a diameter of several centimeters at a higher voltage, is a pulsed discharge despite a DC voltage is applied. The pulse frequency is investigated as a function of the voltage under different gap widths and gas flow rates. Results show that plasma bullets propagate from the hollow needle to the plate electrode by spatially resolved measurement. A supposition about non-electroneutral trail of the streamer is proposed to interpret these experimental phenomena.

  1. Purification of six lignans from the stems of Schisandra chinensis by using high-speed counter-current chromatography combined with preparative high-performance liquid chromatography.

    PubMed

    Zhu, Lijie; Li, Bin; Liu, Xiuying; Huang, Guohui; Meng, Xianjun

    2015-11-01

    A method for the preparative purification of lignans from Schisandra chinensis was established using a combination of high-speed counter-current chromatography (HSCCC) and preparative high-performance liquid chromatography (HPLC). The crude extracts obtained from S. chinensis by using 70% ethanol were separated on a macroporous resin column and then eluted with a graded ethanol series. A two-phase solvent system consisting of n-hexane-ethyl acetate-methanol-water (1:1:1:1, v/v) was used for HSCCC, and a mobile phase of acetonitrile-water (50:50, v/v) was used for preparative HPLC. The results obtained using HSCCC were compared with those obtained using preparative HPLC, and their advantages were further integrated to improve the separation efficiency. Six known lignans were identified by electrospray ionisation mass spectrometry and (1)H nuclear magnetic resonance (NMR) and (13)C NMR analyses; the purities of all the compounds were more than 91%.

  2. Preparative Separation of N-Feruloyl Serotonin and N-(p-Coumaroyl) Serotonin from Safflower Seed Meal Using High-Speed Counter-Current Chromatography.

    PubMed

    Zhang, Qiulong; Hu, Na; Li, Wencong; Ding, Chenxi; Ma, Tao; Bai, Bo; Wang, Honglun; Suo, Yourui; Wang, Xiaoyan; Ding, Chenxu

    2015-09-01

    High-speed counter-current chromatography (HSCCC) was successfully applied for the preparative separation and purification of N-feruloyl serotonin (NF) and N-(p-coumaroyl) serotonin (NP) from safflower seed meal. After the measurement of partition coefficient of the two target compounds in the two-phase solvent systems, the HSCCC was performed well with a two-phase solvent system composed of CHCl3-methanol-0.1 M HCl at a volume ratio of 1 : 1 : 1, v/v. The upper phase was used as stationary phase and the lower phase was used as mobile phase. Under the optimized condition, 7.5 mg NF and 6.9 mg NP were separated from 40 mg crude sample with the purity of 98.8 and 97.3%, respectively. The structures of the isolated compounds were identified by (1)H NMR and (13)C NMR.

  3. Isolation and purification of three flavonoid glycosides from the leaves of Nelumbo nucifera (Lotus) by high-speed counter-current chromatography.

    PubMed

    Deng, Shengguo; Deng, Zeyuan; Fan, Yawei; Peng, You; Li, Jing; Xiong, Dongmei; Liu, Rong

    2009-08-15

    Semi-preparative high-speed counter-current chromatography (HSCCC) was successfully used for isolation and purification of flavonoid glycosides from the leaves of Nelumbo nucifera (Lotus) by using a two-phase-solvent system composed of n-hexane-ethyl acetate-methanol-water (1:5:1:5, v/v/v/v). The targeted compounds isolated, collected and purified by HSCCC were analyzed by high performance liquid chromatography (HPLC). A total of 4.6 mg of isoquercitrin, 9.1 mg of hyperoside and 3.0 mg of astragalin with the purity of 95.8%, 97.5% and 98.3%, respectively, were obtained in one-step separation and less than 6 h from 80 mg of crude extract from the leaves of N. nucifera. The chemical structures of all the three compounds were identified by MS, (1)H NMR, (13)C NMR. Astragalin was obtained from N. nucifera for the first time.

  4. Preparative isolation and purification of macrolactin antibiotics from marine bacterium Bacillus amyloliquefaciens using high-speed counter-current chromatography in stepwise elution mode.

    PubMed

    He, Shan; Wang, Hongqiang; Yan, Xiaojun; Zhu, Peng; Chen, Juanjuan; Yang, Rui

    2013-01-11

    Preparative high-speed counter-current chromatography (HSCCC) was successfully applied to the isolation and purification of two macrolactin antibiotics from marine bacterium Bacillus amyloliquefaciens for the first time using stepwise elution with a pair of two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water at (1:4:1:4, v/v) and (3:4:3:4, v/v). The preparative HSCCC separation was performed on 300 mg of crude sample yielding macrolactin B (22.7 mg) and macrolactin A (40.4 mg) in a one-step separation, with purities over 95% as determined by HPLC. The structures of these compounds were identified by MS, (1)H NMR and (13)C NMR. Our results demonstrated that HSCCC was an efficient technique to separate marine antibiotics, which provide an approach to solve the problem of their sample availability for drug development.

  5. Preparative isolation and purification of harpagoside and angroside C from the root of Scrophularia ningpoensis Hemsley by high-speed counter-current chromatography.

    PubMed

    Tian, Jinfeng; Ye, Xiaoli; Shang, Yuanhong; Deng, Yafei; He, Kai; Li, Xuegang

    2012-10-01

    In this study, the bioactive component harpagoside and angroside C in the root of Scrophularia ningpoensis Hemsley was simultaneously separated by high-speed counter-current chromatography (HSCCC). A two-phase solvent system containing chloroform/n-butanol/methanol/water (4:1:3:2, v/v/v/v) was selected following consideration of the partition coefficient of the target compound. The crude extract (200 mg) was loaded onto a 280-mL HSCCC column and yielded 22 mg harpagoside and 31 mg angroside C with the purity of higher than 98 and 98.5%, respectively. It is feasible to isolate active compounds harpagoside and angroside C from S. ningpoensis using HSCCC.

  6. Separation of five flavonoids from tartary buckwheat (Fagopyrum tataricum (L.) Gaertn) grains via off-line two dimensional high-speed counter-current chromatography.

    PubMed

    Jiang, Shujing; Liu, Qi; Xie, Yixi; Zeng, Hualiang; Zhang, Li; Jiang, Xinyu; Chen, Xiaoqing

    2015-11-01

    An off-line two dimensional (2D) high-speed counter-current chromatography (HSCCC) strategy was successfully used for preparative separation of five flavonoids from tartary buckwheat (Fagopyrum tataricum (L.) Gaertn) grains with different solvent systems for the first time in this paper. n-Hexane-ethyl acetate-methanol-water 3:5:3:5 (v/v) was selected as the first dimension solvent system to purify quercetin (4) and kaempferol (5). The second dimension solvent system, ethyl acetate-n-butanol-water 7:3:10 (v/v), was used to isolate quercetin 3-O-rutinoside-3'-O-β-glucopyranoside (1), rutin (2) and kaempferol 3-rutinoside (3). The purities of these compounds were all above 96.0% and their structures were identified through UV, MS and (1)H NMR. The results indicated that the off-line 2D HSCCC is an efficient technique to isolate flavonoids compounds from grains.

  7. Liquid-liquid/solid three-phase high-speed counter-current chromatography, a new technique for separation of polyphenols from Geranium wilfordii Maxim.

    PubMed

    Liu, Dan; Ma, Yan; Gu, Ming; Janson, Jan-Christer; Wang, Changhai; Xiao, Hongbin

    2012-08-01

    High-speed counter-current chromatography using a new liquid-liquid/solid three-phase system was used for the separation of the polyphenols corilagin and geraniin from a crude extract of Geranium wilfordii Maxim in one step. The optimized three-phase system was composed of n-hexane/ethyl acetate/methanol/acetic acid/water and to which was added 10-μm average diameter microspheres of cross-linked 12% agarose at the ratio of 0.2:10:2:1:5 and 0.1 g/mL, respectively. The purities of geraniin and corilagin were 82 and 90%, which were determined by HPLC at 280 nm. A 14.5 and 7 mg of geraniin and corilagin were purified from 160 mg crude extract with the yields of 70 and 78%, respectively.

  8. Comprehensive separation of secondary metabolites in natural products by high-speed counter-current chromatography using a three-phase solvent system.

    PubMed

    Yanagida, Akio; Yamakawa, Yutaka; Noji, Ryoko; Oda, Ako; Shindo, Heisaburo; Ito, Yoichiro; Shibusawa, Yoichi

    2007-06-01

    High-speed counter-current chromatography (HSCCC) using the three-phase solvent system n-hexane-methyl acetate-acetonitrile-water at a volume ratio of 4:4:3:4 was applied to the comprehensive separation of secondary metabolites in several natural product extracts. A wide variety of secondary metabolites in each natural product was effectively extracted with the three-phase solvent system, and the filtered extract was directly submitted to the HSCCC separation using the same three-phase system. In the HSCCC profiles of crude natural drugs listed in the Japanese Pharmacopoeia, several physiologically active compounds were clearly separated from other components in the extracts. The HSCCC profiles of several tea products, each manufactured by a different process, clearly showed their compositional difference in main compounds such as catechins, caffeine, and pigments. These HSCCC profiles also provide useful information about hydrophobic diversity of whole components present in each natural product.

  9. Application of the ultrasonic technique and high-speed filming for the study of the structure of air-water bubbly flows

    SciTech Connect

    Carvalho, R.D.M.; Venturini, O.J.; Tanahashi, E.I.; Neves, F. Jr.; Franca, F.A.

    2009-10-15

    Multiphase flows are very common in industry, oftentimes involving very harsh environments and fluids. Accordingly, there is a need to determine the dispersed phase holdup using noninvasive fast responding techniques; besides, knowledge of the flow structure is essential for the assessment of the transport processes involved. The ultrasonic technique fulfills these requirements and could have the capability to provide the information required. In this paper, the potential of the ultrasonic technique for application to two-phase flows was investigated by checking acoustic attenuation data against experimental data on the void fraction and flow topology of vertical, upward, air-water bubbly flows in the zero to 15% void fraction range. The ultrasonic apparatus consisted of one emitter/receiver transducer and three other receivers at different positions along the pipe circumference; simultaneous high-speed motion pictures of the flow patterns were made at 250 and 1000 fps. The attenuation data for all sensors exhibited a systematic interrelated behavior with void fraction, thereby testifying to the capability of the ultrasonic technique to measure the dispersed phase holdup. From the motion pictures, basic gas phase structures and different flows patterns were identified that corroborated several features of the acoustic attenuation data. Finally, the acoustic wave transit time was also investigated as a function of void fraction. (author)

  10. Air temperature, wind speed, and wind direction in the National Petroleum Reserve—Alaska and the Arctic National Wildlife Refuge, 1998–2011

    USGS Publications Warehouse

    Urban, Frank E.; Clow, Gary D.

    2013-01-01

    This report provides air temperature, wind speed, and wind direction data collected on Federal lands in Arctic Alaska over the period August 1998 to July 2011 by the U.S. Department of the Interior's climate monitoring array, part of the Global Terrestrial Network for Permafrost. In addition to presenting data, this report also describes monitoring, data collection, and quality control methodology. This array of 16 monitoring stations spans 68.5°N to 70.5°N and 142.5°W to 161°W, an area of roughly 150,000 square kilometers. Climate summaries are presented along with provisional quality-controlled data. Data collection is ongoing and includes several additional climate variables to be released in subsequent reports, including ground temperature and soil moisture, snow depth, rainfall, up- and downwelling shortwave radiation, and atmospheric pressure. These data were collected by the U.S. Geological Survey in close collaboration with the Bureau of Land Management and the U.S. Fish and Wildlife Service.

  11. Influence of air pressure, humidity, solar radiation, temperature, and wind speed on ambulatory visits due to chronic obstructive pulmonary disease in Bavaria, Germany

    NASA Astrophysics Data System (ADS)

    Ferrari, Uta; Exner, Teresa; Wanka, Eva R.; Bergemann, Christoph; Meyer-Arnek, Julian; Hildenbrand, Beate; Tufman, Amanda; Heumann, Christian; Huber, Rudolf M.; Bittner, Michael; Fischer, Rainald

    2012-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the most important causes of morbidity and mortality in the world. The disease is often aggravated by periods of increased symptoms requiring medical attention. Among the possible triggers for these exacerbations, meteorological factors are under consideration. The objective of this study was to assess the influence of various meteorological factors on the health status of patients with COPD. For this purpose, the daily number of ambulatory care visits due to COPD was analysed in Bavaria, Germany, for the years 2006 and 2007. The meteorological factors were provided by the model at the European Centre for Medium Range Weather Forecast (ECMWF). For the multivariate analysis, a generalised linear model was used. In Bavaria, an increase of 1% of daily consultations (about 103 visits per day) was found to be associated with a change of 0.72 K temperature, 209.55 of log air surface pressure in Pa, and a decrease of 1% of daily consultations with 1,453,763 Ws m2 of solar radiation. There also seem to be regional differences between north and south Bavaria; for instance, the effect of wind speed and specific humidity with a lag of 1 day were only significant in the north. This study could contribute to a tool for the prevention of exacerbations. It also serves as a model for the further evaluation of the impact of meteorological factors on health, and could easily be applied to other diseases or other regions.

  12. Influence of air pressure, humidity, solar radiation, temperature, and wind speed on ambulatory visits due to chronic obstructive pulmonary disease in Bavaria, Germany.

    PubMed

    Ferrari, Uta; Exner, Teresa; Wanka, Eva R; Bergemann, Christoph; Meyer-Arnek, Julian; Hildenbrand, Beate; Tufman, Amanda; Heumann, Christian; Huber, Rudolf M; Bittner, Michael; Fischer, Rainald

    2012-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the most important causes of morbidity and mortality in the world. The disease is often aggravated by periods of increased symptoms requiring medical attention. Among the possible triggers for these exacerbations, meteorological factors are under consideration. The objective of this study was to assess the influence of various meteorological factors on the health status of patients with COPD. For this purpose, the daily number of ambulatory care visits due to COPD was analysed in Bavaria, Germany, for the years 2006 and 2007. The meteorological factors were provided by the model at the European Centre for Medium Range Weather Forecast (ECMWF). For the multivariate analysis, a generalised linear model was used. In Bavaria, an increase of 1% of daily consultations (about 103 visits per day) was found to be associated with a change of 0.72 K temperature, 209.55 of log air surface pressure in Pa, and a decrease of 1% of daily consultations with 1,453,763 Ws m(2) of solar radiation. There also seem to be regional differences between north and south Bavaria; for instance, the effect of wind speed and specific humidity with a lag of 1 day were only significant in the north. This study could contribute to a tool for the prevention of exacerbations. It also serves as a model for the further evaluation of the impact of meteorological factors on health, and could easily be applied to other diseases or other regions.

  13. Continued investigations in the NAAL low speed wind tunnel into the effects of the air breathing propulsion system on orbiter subsonic stability and control characteristics (OA62A)

    NASA Technical Reports Server (NTRS)

    Mennell, R.

    1974-01-01

    Experimental aerodynamic investigations were conducted on a stingmounted 0.0405-scale representation (model 43-0) of the 140A/B Space Shuttle Orbiter in a Low Speed Wind Tunnel. The NASA designation for this test was 0A62A. The primary test objective was to continue studies, initiated on tests 0A16 and 0A71A and 0A71C, in optimizing the air breathing propulsion system (ABPS) and investigating the aerodynamic effects of various nacelle number/location configurations on the orbiter stability and control characteristics. Orbiter stability and control characteristics, both with and without ABPS, were investigated at elevon deflections of 0, + or -5, + or -19, + or -5, and -20 deg; aileron deflections of 0 and 10 deg (about 0 deg elevon); and rudder deflections of 0, -7.5, and -15 deg. Aerodynamic force and moment data was measured in the body axis system by a 2.5-inch task type internal balance. The model was sting supported through the base region with a nominal angle of attack range of -4 to 30 deg. Yaw polars were recorded over the beta range of -10 to 10 deg at fixed angles of attack of 0, 5, 10, and 15 deg.

  14. Chemical Transport and Reduced-Form Models for Assessing Air Quality Impacts of Current and Future Energy Scenarios

    NASA Astrophysics Data System (ADS)

    Adams, P. J.

    2015-12-01

    Though essential for informed decision-making, it is challenging to estimate the air quality and public health impacts associated with current and future energy generation scenarios because the analysis must address the complicated atmospheric processes that air pollutants undergo: emissions, dispersion, chemistry, and removal. Employing a chemical transport model (CTM) is the most rigorous way to address these atmospheric processes. However, CTMs are expensive from a computational standpoint and, therefore, beyond the reach of policy analysis for many types of problems. On the other hand, previously available reduced-form models used for policy analysis fall short of the rigor of CTMs and may lead to biased results. To address this gap, we developed the Estimating Air pollution Social Impacts Using Regression (EASIUR) method, which builds parameterizations that predict per-tonne social costs and intake fractions for pollutants emitted from any location in the United States. Derived from a large database of tagged CTM simulations, the EASIUR method predicts social costs almost indistinguishable from a full CTM but with negligible computational requirements. We found that the average mortality-related social costs from inorganic PM2.5 and its precursors in the United States are 150,000-180,000/t EC, 21,000-34,000/t SO2, 4,200-15,000/t NOx, and 29,000-85,000/t NH3. This talk will demonstrate examples of using both CTMs and reduced-form models for assessing air quality impacts associated with current energy production activities as well as a future deployment of carbon capture and sequestration.

  15. Low dark current and high speed ZnO metal–semiconductor–metal photodetector on SiO{sub 2}/Si substrate

    SciTech Connect

    Çalışkan, Deniz; Bütün, Bayram; Çakır, M. Cihan; Özcan, Şadan; Özbay, Ekmel

    2014-10-20

    ZnO thin films are deposited by radio-frequency magnetron sputtering on thermally grown SiO{sub 2} on Si substrates. Pt/Au contacts are fabricated by standard photolithography and lift-off in order to form a metal-semiconductor-metal (MSM) photodetector. The dark current of the photodetector is measured as 1 pA at 100 V bias, corresponding to 100 pA/cm{sup 2} current density. Spectral photoresponse measurement showed the usual spectral behavior and 0.35 A/W responsivity at a 100 V bias. The rise and fall times for the photocurrent are measured as 22 ps and 8 ns, respectively, which are the lowest values to date. Scanning electron microscope image shows high aspect ratio and dense grains indicating high surface area. Low dark current density and high speed response are attributed to high number of recombination centers due to film morphology, deducing from photoluminescence measurements. These results show that as deposited ZnO thin film MSM photodetectors can be used for the applications needed for low light level detection and fast operation.

  16. Distribution and air-sea exchange of current-use pesticides (CUPs) from East Asia to the high Arctic Ocean.

    PubMed

    Zhong, Guangcai; Xie, Zhiyong; Cai, Minghong; Möller, Axel; Sturm, Renate; Tang, Jianhui; Zhang, Gan; He, Jianfeng; Ebinghaus, Ralf

    2012-01-01

    Surface seawater and marine boundary layer air samples were collected on the ice-breaker R/V Xuelong (Snow Dragon) from the East China Sea to the high Arctic (33.23-84.5° N) in July to September 2010 and have been analyzed for six current-use pesticides (CUPs): trifluralin, endosulfan, chlorothalonil, chlorpyrifos, dacthal, and dicofol. In all oceanic air samples, the six CUPs were detected, showing highest level (>100 pg/m(3)) in the Sea of Japan. Gaseous CUPs basically decreased from East Asia (between 36.6 and 45.1° N) toward Bering and Chukchi Seas. The dissolved CUPs in ocean water ranged widely from air. Trifluralin in seawater was relatively high in the Sea of Japan (35.2° N) and evenly distributed between 36.9 and 72.5° N, but it remained below the detection limit at the highest northern latitudes in Chukchi Sea. In contrast with other CUPs, concentrations of chlorothalonil and dacthal were more abundant in Chukchi Sea and in East Asia. The air-sea gas exchange of CUPs was generally dominated by net deposition. Latitudinal trends of fugacity ratios of α-endosulfan, chlorothalonil, and dacthal showed stronger deposition of these compounds in East Asia than in Chukchi Sea, while trifluralin showed stronger deposition in Chukchi Sea (-455 ± 245 pg/m(2)/day) than in the North Pacific (-241 ± 158 pg/m(2)/day). Air-sea gas exchange of chlorpyrifos varied from net volatilizaiton in East Asia (<40° N) to equilibrium or net deposition in the North Pacific and the Arctic.

  17. Characteristics of Arc Voltage of High-Current Air Arc in Sealed Chamber

    NASA Astrophysics Data System (ADS)

    Watanabe, Shinya; Kokura, Kentaro; Minoda, Kyohei; Sato, Shinji

    Effect of arc voltage on different factor of design and control was investigated for high current in order to develop design guide of circuit breaker. In this study, dependences on these factors which are current, arc length, surface area on electrode and internal pressure of arc voltage were evaluated quantitatively. As a result of the evaluations, it was estimated that arc voltage near electrode surface rise linearly with arc current and the area on the surface to the power -0.8, and the voltage in arc column rise pressure increase to the power 0.3. We confirmed the validity of the characteristics of the estimated voltage by comparison with the generated voltage in an actual arc extinguishing chamber. The characteristics of the estimated voltage would be provided as effective guidelines to design arc extinguishing chambers.

  18. A new method for infrared imaging of air currents in and around critical hazard fume hoods

    SciTech Connect

    Mulac, W.A.; McCreary, J.R. ); Schmalz, H. Thermal Surveys, Inc., Rockford, IL )

    1992-01-01

    A real time method of measuring and recording the efficacy of vapor containment in and around critical hazard fume hoods is being developed. An infrared camera whose response is restricted to a spectral range that overlaps a strong absorption band in a non-toxic gas is used to render real-time video images of the presence and flow of the gas. The gas, nitrous oxide, is ejected in a continuous stream in and around fume hoods that are to be certified capable of containing hazardous fumes. The principle advantage is that various scenarios of air flow displacement in and outside the hood can be easily investigated; the principle limitation is the necessity of high tracer gas concentration to obtain strong visualizations. We hope that this technique can be found to be an effective and safe method to test hoods in locations that were built before present regulations were promulgated.

  19. A new method for infrared imaging of air currents in and around critical hazard fume hoods

    SciTech Connect

    Mulac, W.A.; McCreary, J.R.; Schmalz, H. |

    1992-11-01

    A real time method of measuring and recording the efficacy of vapor containment in and around critical hazard fume hoods is being developed. An infrared camera whose response is restricted to a spectral range that overlaps a strong absorption band in a non-toxic gas is used to render real-time video images of the presence and flow of the gas. The gas, nitrous oxide, is ejected in a continuous stream in and around fume hoods that are to be certified capable of containing hazardous fumes. The principle advantage is that various scenarios of air flow displacement in and outside the hood can be easily investigated; the principle limitation is the necessity of high tracer gas concentration to obtain strong visualizations. We hope that this technique can be found to be an effective and safe method to test hoods in locations that were built before present regulations were promulgated.

  20. Note: Measurement of extreme-short current pulse duration of runaway electron beam in atmospheric pressure air

    SciTech Connect

    Tarasenko, V. F.; Rybka, D. V.; Burachenko, A. G.; Lomaev, M. I.; Balzovsky, E. V.

    2012-08-15

    This note reports the time-amplitude characteristic of the supershort avalanche electron beam with up to 20 ps time resolution. For the first time it is shown that the electron beam downstream of small-diameter diaphragms in atmospheric pressure air has a complex structure which depends on the interelectrode gap width and cathode design. With a spherical cathode and collimator the minimum duration at half maximum of the supershort avalanche electron beam current pulse was shown to be {approx}25 ps. The minimum duration at half maximum of one peak in the pulses with two peaks can reach {approx}25 ps too.

  1. Air pollution control residues from waste incineration: current UK situation and assessment of alternative technologies.

    PubMed

    Rani, D Amutha; Boccaccini, A R; Deegan, D; Cheeseman, C R

    2008-11-01

    Current disposal options for APC residues in the UK and alternative treatment technologies developed world-wide have been reviewed. APC residues are currently landfilled in the UK where they undergo in situ solidification, although the future acceptability of this option is uncertain because the EU waste acceptance criteria (WAC) introduce strict limits on leaching that are difficult to achieve. Other APC residue treatment processes have been developed which are reported to reduce leaching to below relevant regulatory limits. The Ferrox process, the VKI process, the WES-PHix process, stabilisation/solidification using cementitious binders and a range of thermal treatment processes are reviewed. Thermal treatment technologies convert APC residues combined with other wastes into inert glass or glass-ceramics that encapsulate heavy metals. The waste management industry will inevitably use the cheapest available option for treating APC residues and strict interpretation and enforcement of waste legislation is required if new, potentially more sustainable technologies are to become commercially viable.

  2. The current status of the GRAPES-3 extensive air shower experiment

    NASA Astrophysics Data System (ADS)

    Gupta, S. K.; Antia, H. M.; Dugad, S. R.; Goswami, U. D.; Hayashi, Y.; Iyer, A.; Ito, N.; Jagadeesan, P.; Jain, A.; Karthikeyan, S.; Kawakami, S.; Minamino, M.; Mohanty, P. K.; Morris, S. D.; Nayak, P. K.; Nonaka, T.; Oshima, A.; Rao, B. S.; Ravindran, K. C.; Tanaka, H.; Tonwar, S. C.; Grapes-3 Collaboration

    2009-12-01

    The GRAPES-3 is a dense extensive air shower array operating with ˜400 scintillator detectors and it also contains a 560 m 2 tracking muon detector ( E>1 GeV), at Ooty in India. 25% of scintillator detectors are instrumented with two fast photomultiplier tubes (PMTs) for extending the dynamic range to ˜5×10 particles m -2 . The scintillators, signal processing electronics and data recording systems were fabricated in-house to cut costs and optimize performance. The muon multiplicity distribution of the EAS is used to probe the composition of primary cosmic rays below the 'knee', with an overlap with direct measurements. Search for multi-TeV γ-rays from point sources is done with the aid of the muon detector. A good angular resolution of 0.7° at 30 TeV, is measured from the shadow of the Moon on the isotropic flux of cosmic rays. A sensitive limit on the diffuse flux of 100 TeV γ-rays is placed by using muon detector to filter the charged cosmic ray background. A tracking muon detector allows sensitive measurements on coronal mass ejections and solar flares through Forbush decrease events. We have major expansion plans to enhance the sensitivity of the GRAPES-3 experiment in the areas listed above.

  3. The current practice of health risk assessment: Potential impact on standards for toxic air contaminants

    SciTech Connect

    Paustenbach, D.J.; Jernigan, J.D.; Finley, B.L.; Ripple, S.R.; Keenan, R.E. )

    1990-12-01

    Since the Bhopal incident, the public has placed pressure on regulatory agencies to set community exposure limits for the dozens of chemicals that may be released by manufacturing facilities. More or less objective limits can be established for the vast majority of these chemicals through the use of risk assessment. However, each step of the risk assessment process (i.e., hazard identification, dose-response assessment, exposure assessment, and risk characterization) contains a number of pitfalls that scientists need to avoid to ensure that valid limits are established. For example, in the hazard identification step there has been little discrimination among animal carcinogens with respect to mechanism of action or the epidemiology experience. In the dose-response portion, rarely is the range of plausible estimated risks presented. Physiologically based pharmacokinetic (PB-PK) models should be used to understand the difference between the tissue doses and the administered dose, as well as the difference in target tissue concentrations of the toxicant between rodents and humans. Biologically-based models like the Moolgavkar-Knudson-Venzon (MKV) should be developed and used, when appropriate. The exposure assessment step can be significantly improved by using more sensitive and specific sampling and analytical methods, more accurate exposure parameters, and computer models that can account for complex environmental factors. Whenever possible, model predictions of exposure and uptake should be validated by biological monitoring of exposed persons (urine, blood, adipose) or by field measurements of plants, soil, fish, air, or water. In each portion of an assessment, the weight of evidence approach should be used to identify the most defensible value. 129 refs.

  4. Effects of ambient air temperature, humidity, and wind speed on seminal traits in Braford and Nellore bulls at the Brazilian Pantanal

    NASA Astrophysics Data System (ADS)

    Menegassi, Silvio Renato Oliveira; Pereira, Gabriel Ribas; Bremm, Carolina; Koetz, Celso; Lopes, Flávio Guiselli; Fiorentini, Eduardo Custódio; McManus, Concepta; Dias, Eduardo Antunes; da Rocha, Marcela Kuczynski; Lopes, Rubia Branco; Barcellos, Júlio Otávio Jardim

    2016-04-01

    The aim of this study was to evaluate the bioclimatic thermal stress assessed by Equivalent Temperature Index (ETI) and Temperature Humidity Index (THI) on Braford and Nellore bulls sperm quality during the reproductive seasons at the tropical region in the Brazilian Pantanal. We used 20 bulls aged approximately 24 months at the beginning of the study. Five ejaculates per animal were collected using an electroejaculator. Temperature, air humidity, and wind speed data were collected every hour from the automatic weather station at the National Institute of Meteorology. Infrared thermography images data were collected to assess the testicular temperature gradient in each animal. Data were analyzed with ANOVA using MIXED procedure of SAS and means were compared using Tukey's HSD test. The THI and ETI at 12 days (epididymal transit) were higher in January (89.7 and 28.5, respectively) and February (90.0 and 29.0, respectively) compared to other months (P < 0.01). Total seminal defects differ only in Bradford bulls between the months of November and February. Nellore bulls had lower major defects (MaD) and total defects (TD) compared to Braford. Nellore bulls showed correlation between minor defects (MiD) and THI for 30 days (0.90) and 18 days (0.88; P < 0.05). Braford bulls showed correlation for MaD (0.89) in ETI for 12 days (P < 0.05). Infrared thermography showed no difference between animals. Reproductive response to environmental changes is a consequence of Nellore and Braford adaptation to climate stress conditions. Both THI and ETI environmental indexes can be used to evaluate the morphological changes in the seminal parameters in Nellore or Braford bulls; however, more experiments should be performed focusing on larger sample numbers and also in reproductive assessment during the consecutive years to assess fertility potential.

  5. On the physical processes ruling an atmospheric pressure air glow discharge operating in an intermediate current regime

    NASA Astrophysics Data System (ADS)

    Prevosto, L.; Kelly, H.; Mancinelli, B.; Chamorro, J. C.; Cejas, E.

    2015-02-01

    Low-frequency (100 Hz), intermediate-current (50 to 200 mA) glow discharges were experimentally investigated in atmospheric pressure air between blunt copper electrodes. Voltage-current characteristics and images of the discharge for different inter-electrode distances are reported. A cathode-fall voltage close to 360 V and a current density at the cathode surface of about 11 A/cm2, both independent of the discharge current, were found. The visible emissive structure of the discharge resembles to that of a typical low-pressure glow, thus suggesting a glow-like electric field distribution in the discharge. A kinetic model for the discharge ionization processes is also presented with the aim of identifying the main physical processes ruling the discharge behavior. The numerical results indicate the presence of a non-equilibrium plasma with rather high gas temperature (above 4000 K) leading to the production of components such as NO, O, and N which are usually absent in low-current glows. Hence, the ionization by electron-impact is replaced by associative ionization, which is independent of the reduced electric field. This leads to a negative current-voltage characteristic curve, in spite of the glow-like features of the discharge. On the other hand, several estimations show that the discharge seems to be stabilized by heat conduction; being thermally stable due to its reduced size. All the quoted results indicate that although this discharge regime might be considered to be close to an arc, it is still a glow discharge as demonstrated by its overall properties, supported also by the presence of thermal non-equilibrium.

  6. On the physical processes ruling an atmospheric pressure air glow discharge operating in an intermediate current regime

    SciTech Connect

    Prevosto, L. Mancinelli, B.; Chamorro, J. C.; Cejas, E.; Kelly, H.

    2015-02-15

    Low-frequency (100 Hz), intermediate-current (50 to 200 mA) glow discharges were experimentally investigated in atmospheric pressure air between blunt copper electrodes. Voltage–current characteristics and images of the discharge for different inter-electrode distances are reported. A cathode-fall voltage close to 360 V and a current density at the cathode surface of about 11 A/cm{sup 2}, both independent of the discharge current, were found. The visible emissive structure of the discharge resembles to that of a typical low-pressure glow, thus suggesting a glow-like electric field distribution in the discharge. A kinetic model for the discharge ionization processes is also presented with the aim of identifying the main physical processes ruling the discharge behavior. The numerical results indicate the presence of a non-equilibrium plasma with rather high gas temperature (above 4000 K) leading to the production of components such as NO, O, and N which are usually absent in low-current glows. Hence, the ionization by electron-impact is replaced by associative ionization, which is independent of the reduced electric field. This leads to a negative current-voltage characteristic curve, in spite of the glow-like features of the discharge. On the other hand, several estimations show that the discharge seems to be stabilized by heat conduction; being thermally stable due to its reduced size. All the quoted results indicate that although this discharge regime might be considered to be close to an arc, it is still a glow discharge as demonstrated by its overall properties, supported also by the presence of thermal non-equilibrium.

  7. Unrealistically pristine air in the Arctic produced by current global scale models

    PubMed Central

    Sato, Yousuke; Miura, Hiroaki; Yashiro, Hisashi; Goto, Daisuke; Takemura, Toshihiko; Tomita, Hirofumi; Nakajima, Teruyuki

    2016-01-01

    Black carbon aerosol (BCA) in the Arctic has profound impacts on the global climate system through radiation processes. Despite its enormous impacts, current global scale models, powerful tools for estimating overall impact, tend to underestimate the levels of BCA in the Arctic over several seasons. Using a global aerosol transport simulation with a horizontal grid resolution of 3.5 km, we determined that a higher resolution significantly reduced the underestimation of BCA levels in the Arctic, mainly due to an enhancement of the representation of low-pressure and frontal systems. The BCA mass loading in the Arctic simulated with 3.5-km grid resolution was 4.2-times larger than that simulated with coarse (56-km) grid resolution. Our results also indicated that grid convergence had not occurred on both the contrast between the cloud/cloud free areas and the poleward BCA mass flux, despite the use of the 3.5-km grid resolution. These results suggest that a global aerosol transport simulation using kilometre-order or finer grid resolution is required for more accurate estimation of the distribution of pollutants in the Arctic. PMID:27222352

  8. Application of high-speed counter-current chromatography for isolation of triterpenes from Schisandra Chinensis (Turcz.) Baill and induction apoptosis mechanism of HSC-T6.

    PubMed

    Li, Bin; Meng, Xianjun; Zhu, Lijie; Jiao, Xinyao; Zhang, Jiachen

    2014-01-01

    Triterpenes have shown many beneficial activities in researches, but their separation and preparation usually require multiple methods. Following an initial cleaning-up step on the AB-8 macroporous resin, a preparative high-speed counter-current chromatography (HSCCC) with a two-phase solvent system comprising chloroform-n-butyl alcohol-methanol-water (10:1:7:4, v/v/v/v) was used to isolate and separate triterpenes from caculis of Schisandra Chinensis (Turcz.) baill. A total of 89 mg corosolic acid with purities of 98.5% were obtained from 400 mg crude extract in one-step elution and less than 4 h, and the structure identification was performed by UV, IR, MS, 1H NMR and 13C NMR. The inhibition on liver fibrosis activities of the triterpenes against HSC-T6 in vitro were studied by cell culture methods. The results showed that the corosolic acid have better inhibitory effects on HSC-T6 cells with the IC50 value of 5~25 μg/mL and the study also indicated that corosolic acid might be a potential Chinese medical component to inhibit liver fibrosis.

  9. Efficient preparative isolation and identification of walnut bioactive components using high-speed counter-current chromatography and LC-ESI-IT-TOF-MS.

    PubMed

    Grace, Mary H; Warlick, Charles W; Neff, Scott A; Lila, Mary Ann

    2014-09-01

    Preparative isolation of complex mixtures of compounds from walnut polar extracts was established by a combination of high-speed counter-current chromatography (HSCCC) and electrospray ionization-ion trap-time of flight mass spectrometry (ESI-IT-TOF-MS). Compounds were isolated after a solvent optimisation selection based on solute distribution in a biphasic solvent system. Isolation was achieved through one or two successive HSCCC runs, and final purification on Sephadex LH-20. Isolated compounds included ellagitannins (1-11), gallic acid (12), dicarboxylic acid glucosides (13-15), hydrojuglone glucoside (16), catechin (17), procyanidin B2 (18), and megasterone glucosides (19-20). Praecoxin D (4) was isolated for the first time from walnut, while praecoxin A methyl ester (5) and glansreginin A n-butyl ester (14) are newly identified compounds. The purity and identity of isolated compounds were confirmed by NMR and HPLC-ESI-MS/MS. These results provided a foundation for in depth characterisation of walnut compounds and offered an efficient strategy for isolation of potentially health-relevant phytochemicals from walnuts.

  10. Separation and identification of polyphenols in apple pomace by high-speed counter-current chromatography and high-performance liquid chromatography coupled with mass spectrometry.

    PubMed

    Cao, Xueli; Wang, Cong; Pei, Hairun; Sun, Baoguo

    2009-05-01

    Apple pomace, a by-product in the processing of apple juice, was investigated as a potential source of polyphenols. Two methods of separation and purification of polyphenols from apple pomace extract were established by combination of gel chromatography with high-speed counter-current chromatography (HSCCC) and solvent extraction with HSCCC, respectively. The optimal separation was performed on a Sephadex LH-20 column using gradient aqueous ethanol as eluting solvent from 0% to 100% in increments of 10%. HPLC analysis indicated that main polyphenols existed in fractions eluted between 40% and 50% aqueous ethanol. The fractions of interest from column were separated by HSCCC with the solvent system hexane-ethyl acetate-1% aqueous acetic acid (0.5:9.5:10, v/v/v). Ethyl acetate fractionation of the apple pomace extract followed by direct HSCCC separation by the same solvent system in the volume ratio of 1:9:10 also produced a good separation of the main polyphenols of interest. Six high-purity polyphenols were achieved tentatively and identified by HPLC/MS: chlorogenic acid (1, m/z 354), quercetin-3-glucoside/quercetin-3-glacaside (2, m/z 464), quercetin-3-xyloside (3, m/z 434), phloridzin (4, m/z 436), quercetin-3-arabinoside (5, m/z 434), and quercetin-3-rhamnoside (6, m/z 448). These results provided a preliminary foundation for further development and exploration of apple pomace.

  11. Separation of polyphenols from leaves of Malus hupehensis (Pamp.) Rehder by off-line two-dimensional High Speed Counter-Current Chromatography combined with recycling elution mode.

    PubMed

    Liu, Qi; Zeng, Hualiang; Jiang, Shujing; Zhang, Li; Yang, Fuzhu; Chen, Xiaoqing; Yang, Hua

    2015-11-01

    In this study, off-line two-dimensional High Speed Counter-Current Chromatography (2D HSCCC) strategy combined with recycling elution mode was developed to isolate compounds from the ethyl acetate extract of a common green tea--leaves of Malus hupehensis (Pamp.) Rehder. In the orthogonal separation system, a conventional HSCCC was employed for the first dimension and two recycling HSCCCs were used for the second in parallel. Using a solvent system consisting of n-hexane-ethyl acetate-methanol-water (1:4:0.6:4.4, v/v) in the first and second dimension, four compounds including 3-hydroxy-phlorizin (1), phloretin (2), avicularin (3) and kaempferol 3-O-β-D-glucoside (4) were obtained. The purities of these four compounds were all over 95.0% as determined by HPLC. And their structures were all identified through UV, MS and (1)H NMR. It has been demonstrated that the combination of off-line 2D HSCCC with recycling elution mode is an efficient technique to isolate compounds with similar polarities in natural products.

  12. Isolation of two new prenylated flavonoids from Sinopodophyllum emodi fruit by silica gel column and high-speed counter-current chromatography.

    PubMed

    Sun, Yanjun; Sun, Yinshi; Chen, Hui; Hao, Zhiyou; Wang, Junmin; Guan, Yanbin; Zhang, Yanli; Feng, Weisheng; Zheng, Xiaoke

    2014-10-15

    Two new prenylated flavonoids, sinoflavonoids A-B, were isolated from the dried fruits of Sinopodophyllum emodi by silica gel column chromatography (SGCC) and high-speed counter-current chromatography (HSCCC). The 95% ethanol extract was partitioned with petroleum ether, dichloromethane, ethyl acetate, and n-butanol in water, respectively. The ethyl acetate fraction was pre-separated by SGCC with a petroleum ether-acetone gradient. The eluates containing target compounds were further separated by HSCCC with n-hexane-ethyl acetate-methanol-water (4:6:4:4, v/v). Finally, 17.3mg of sinoflavonoid A and 25.9mg of sinoflavonoid B were obtained from 100mg of the pretreated concentrate. The purities of sinoflavonoid A and sinoflavonoid B were 98.47% and 99.38%, respectively, as determined by HPLC. Their structures were elucidated on the basis of spectroscopic evidences (HR-ESI-MS, (1)H-NMR, (13)C-NMR, HSQC, HMBC). The separation procedures proved to be efficient, especially for trace prenylated flavonoids.

  13. Preparative separation and purification of four cis-trans isomers of coumaroylspermidine analogs from safflower by high-speed counter-current chromatography.

    PubMed

    Li, Wen-Cong; Wang, Xiao-Yan; Lin, Peng-Cheng; Hu, Na; Zhang, Qiu-Long; Suo, You-Rui; Ding, Chen-Xu

    2013-11-01

    High-speed counter-current chromatography (HSCCC) was successfully applied for the first time to isolate and purify four cis-trans isomers of coumaroylspermidine analogs from Safflower. HSCCC separation was achieved with a two-phase solvent system composed of chloroform-methanol-water (1:1:1, v/v/v) with the upper phase as the mobile phase. In a single run, a total of 1.3mg of N(1), N(5), N(10)-(E)-tri-p-coumaroylspermidine (EEE), 4.4mg of N(1)(E)-N(5)-(Z)-N(10)-(E)-tri-p-coumaroylspermidine (EZE), 7.2mg of N(1)(Z)-N(5)-(Z)-N(10)-(E)-tri-p-coumaroylspermidine (ZZE), and 11.5mg of N(1),N(5),N(10)-(Z)-tri-p-coumaroylspermidine (ZZZ) were obtained from 100mg of crude sample. High Performance Liquid Chromatography (HPLC) analysis showed that the purities of these four components are 95.5%, 98.1%, 97.5% and 96.2%, respectively. The chemical structures were identified by ESI-MS, (1)H NMR and (13)C NMR.

  14. Preparative Separation of Sulfur-Containing Diketopiperazines from Marine Fungus Cladosporium sp. Using High-Speed Counter-Current Chromatography in Stepwise Elution Mode

    PubMed Central

    Gu, Binbin; Zhang, Yanying; Ding, Lijian; He, Shan; Wu, Bin; Dong, Junde; Zhu, Peng; Chen, Juanjuan; Zhang, Jinrong; Yan, Xiaojun

    2015-01-01

    High-speed counter-current chromatography (HSCCC) was successively applied to the separation of three sulfur-containing diketopiperazines (DKPs) (including two new compounds cladosporin A (1) and cladosporin B (3), and a known compound haematocin (2)) from a marine fungus Cladosporium sp. The two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water at (1:1:1:1, v/v) and (2:1:2:1, v/v), in stepwise elution mode, was used for HSCCC. The preparative HSCCC separation was performed on 300 mg of crude sample yielding 26.7 mg of compound 3 at a purity of over 95%, 53.6 mg of a mixture of compounds 1 and 2, which was further separated by preparative-HPLC yielding 14.3 mg of compound 1 and 25.4 mg of compound 2 each at a purity of over 95%. Their structures were established by spectroscopic methods. The sulfur-containing DKPs suppressed the proliferation of hepatocellular carcinoma cell line HepG2. The present work represents the first application of HSCCC in the efficient preparation of marine fungal natural products. PMID:25584683

  15. Rapid preparative separation of six bioactive compounds from Gentiana crassicaulis Duthie ex Burk. using microwave-assisted extraction coupled with high-speed counter-current chromatography.

    PubMed

    Liang, Jinru; Ito, Yoichiro; Zhang, Xinxin; He, Jiao; Sun, Wenji

    2013-12-01

    A rapid method combining microwave-assisted extraction (MAE) and high-speed counter-current chromatography (HSCCC) was applied for preparative separation of six bioactive compounds including loganic acid (I), isoorientin-4'-O-glucoside (II), 6'-O-β-d-glucopyranosyl gentiopicroside (III), swertiamarin (IV), gentiopicroside (V), sweroside (VI) from traditional Tibetan medicine Gentiana crassicaulis Duthie ex Burk. MAE parameters were predicted by central composite design response surface methodology. That is, 5.0 g dried roots of G. crassicaulis were extracted with 50 mL 57.5% aqueous ethanol under 630 W for 3.39 min. The extract (gentian total glycosides) was separated by HSCCC with n-butanol/ethyl acetate/methanol/1% acetic acid water (7.5:0.5:0.5:3.5, v/v/v/v) using upper phase mobile in tail-to-head elution mode. 16.3, 8.8, 12., 25.1, 40.7, and 21.8 mg of compounds I-VI were obtained with high purities in one run from 500 mg of original sample. The purities and identities of separated components were confirmed using HPLC with photo diode array detection and quadrupole TOF-MS and NMR spectroscopy. The study reveals that response surface methodology is convenient and highly predictive for optimizing extraction process, MAE coupled with HSCCC could be an expeditious method for extraction and separation of phytochemicals from ethnomedicine.

  16. Isolation of α-Amylase Inhibitors from Kadsura longipedunculata Using a High-Speed Counter-Current Chromatography Target Guided by Centrifugal Ultrafiltration with LC-MS.

    PubMed

    Cen, Yin; Xiao, Aiping; Chen, Xiaoqing; Liu, Liangliang

    2016-01-01

    In this study, a high-speed counter-current chromatography (HSCCC) separation method target guided by centrifugal ultrafiltration with high-performance liquid chromatography-mass spectrometry (CU-LC-MS) was proposed. This method was used to analyze α-amylase inhibitors from Kadsura longipedunculata extract. According to previous screening with CU-LC-MS, two screened potential α-amylase inhibitors was successfully isolated from Kadsura longipedunculata extract using HSCCC under the optimized experimental conditions. The isolated two target compounds (with purities of 92.3% and 94.6%) were, respectively, identified as quercetin-3-O-rhamnoside (1) and protocatechuic acid (2) based on the MS, UV, and ¹H-NMR spectrometry data. To verify the inhibition of screened compounds, the inhibitory activities of quercetin-3-O-rhamnoside (1) and protocatechuic acid (2) on α-amylase were tested, and it demonstrated that the experimental IC50 values of quercetin-3-O-rhamnoside (1) and protocatechuic acid (2) were 28.8 and 12.5 μmol/L. These results proved that the hyphenated technique using CU-LC-MS and HSCCC was a rapid, competent, and reproductive method to screen and separate potential active compounds, like enzyme inhibitors from the extract of herbal medicines.

  17. Separation and purification of four oligostilbenes from Iris lactea Pall. var. chinensis (Fisch.) Koidz by high-speed counter-current chromatography.

    PubMed

    Lv, Huanhuan; Wang, Honglun; He, Yanfeng; Ding, Chenxu; Wang, Xiaoyan; Suo, Yourui

    2015-04-15

    A method of using high-speed counter-current chromatography (HSCCC) for preparative isolation and purification of oligostilbenes from the ethanol extracts of seed kernel of Iris lactea Pall. var. chinensis (Fisch.) Koidz was established in this study. Four oligostilbenes were successfully separated and purified by HSCCC with two sets of two-phase solvent system, n-hexane-ethyl acetate-methanol-water (3:6:4.2:5.5, v/v/v/v) in the head-to-tail elution mode for the first separation to mainly isolate vitisin A (58 mg), ɛ-viniferin (76 mg) and peak II (43 mg) from 300 mg of the crude ethanol extracts, and then light petroleum-ethyl acetate-methanol-water (5:5:3:6, v/v/v/v) in the tail-to-head elution mode for the second separation to isolate vitisin B (52 mg) and vitisin C (11 mg) from 100mg of peak II. The purities of the isolated four oligostilbenes were all over 95.0% as determined by HPLC. Vitisin A, vitisin B and vitisin C, resveratrol tetramers, were isolated from Iris lactea for the first time. The preparation of crude sample was simple and the HSCCC method for the isolation and purification of four oligostilbenes was rapid, efficient and economical.

  18. Efficient Preparation of Streptochlorin from Marine Streptomyces sp. SYYLWHS-1-4 by Combination of Response Surface Methodology and High-Speed Counter-Current Chromatography.

    PubMed

    Li, Lin; He, Shan; Ding, Lijian; Yuan, Ye; Zhu, Peng; Epstein, Slava; Fan, Jianzhong; Wu, Xiaokai; Yan, Xiaojun

    2016-01-01

    Since first isolated from the lipophilic extract of Streptomyces sp. SF2583, streptochlorin, has attracted a lot of attention because of its various pharmacological properties, such as antibiotic, antiallergic, antitumor, and anti-inflammatory activities. For the efficient preparation of streptochlorin from a producing strain Streptomyces sp. SYYLWHS-1-4, we developed a combinative method by using response surface methodology (RSM) and high-speed counter-current chromatography (HSCCC). In the fermentation process, we used RSM to optimize the condition for the efficient accumulation of streptochlorin, and the optimal parameters were: yeast extract 1.889 g/L, soluble starch 8.636 g/L, K₂HPO₄ 0.359 g/L, CaCl₂ 2.5 g/L, MgSO₄ 0.625 g/L, marine salt 25 g/L, medium volume 50%, initial pH value 7.0, temperature 27.5 °C, which enhanced streptochlorin yield by 17.7-fold. During the purification process, the preparative HSCCC separation was performed using a petroleum ether-ethyl acetate-methanol-water (9:0.8:5:5, v/v/v/v) biphasic solvent system, where 300 mg of crude sample yielded 16.5 mg streptochlorin with over 95% purity as determined by UPLC. Consequently, the combination method provided a feasible strategy for highly effective preparation of streptochlorin, which ensured the supply of large amounts of streptochlorin for in vivo pharmacological assessments or other requirements.

  19. Bioassay-guided preparative separation of angiotensin-converting enzyme inhibitory C-flavone glycosides from Desmodium styracifolium by recycling complexation high-speed counter-current chromatography.

    PubMed

    Zhang, Ying-Qi; Luo, Jian-Guang; Han, Chao; Xu, Jin-Fang; Kong, Ling-Yi

    2015-01-01

    A new strategy of the convergence of high-speed counter-current chromatography (HSCCC) and bioactive assay technique was developed for rapidly screening and separating the angiotensin-converting enzyme (ACE) inhibitors from the aerial parts of Desmodium styracifolium. Bioactivity-guided fractionation of the crude extract was first established to target the bioactive fractions based on HSCCC coupled with in vitro ACE inhibitory assay. Subsequently, the bioactive fractions were further separated by the recycling complexation HSCCC respectively, using 0.10 mol/L copper sulfate in the lower phase of two-phase solvent system composed of n-butanol/water (1:1, v/v). Five C-glycosylflavones, vicenin 2 (1), carlinoside (2), vicenin 1 (3), schaftoside (4) and vicenin 3 (5), were successfully obtained. Their chemical structures were identified using ESI-MS and NMR. All the isolates showed in vitro ACE inhibitory activity with the IC50 values between 33.62 and 58.37 μM. The results demonstrated that the established method was proposed as an excellent strategy to systematically screen and purify active compounds from traditional Chinese medicines.

  20. One-step separation of nine structural analogues from Poria cocos (Schw.) Wolf. via tandem high-speed counter-current chromatography.

    PubMed

    Zeng, Hualiang; Liu, Qi; Yu, Jingang; Jiang, Xinyu; Wu, Zhiliang; Wang, Meiling; Chen, Miao; Chen, Xiaoqing

    2015-11-01

    A novel one-step separation strategy-tandem high-speed counter-current chromatography (HSCCC) was developed with a six-port valve serving as the switch interface. Nine structural analogues including three isomers were successfully isolated from Poria cocos (Schw.) Wolf. by one step. Compared with conventional HSCCC, peak resolution of target compounds was effectively improved in tandem one. Purities of isolated compounds were all over 90% as determined by HPLC. Their structures were then identified via UV, MS and (1)H NMR, and eventually assigned as poricoic acid B (1), poricoic acid A (2), 3β,16α-dihydroxylanosta-7, 9(11), 24-trien-21-oic acid (3), dehydrotumulosic acid (4), polyporenic acid C (5), 3-epi-dehydrotumulosic acid (6), 3-o-acetyl-16α-hydroxydehydrotrametenolic acid (7), dehydropachymic acid (8) and dehydrotrametenolic acid (9) respectively. The results indicated that tandem HSCCC can effectively improve peak resolution of target compounds, and can be a good candidate for HSCCC separation of structural analogues.

  1. Separation and purification of five phenylpropanoid glycosides from Lamiophlomis rotata (Benth.) Kudo by a macroporous resin column combined with high-speed counter-current chromatography.

    PubMed

    Yue, Hui-Lan; Zhao, Xiao-Hui; Mei, Li-Juan; Shao, Yun

    2013-09-01

    Five phenylethanoid glycosides (PhGs), forsythoside B, verbascoside, alyssonoside, isoverbascoside, and leucosceptoside B, were isolated and purified from Lamiophlomis rotata (Benth.) Kudo by high-speed counter-current chromatography (HSCCC) combined with macroporous resin (MR) column separation. In the present study, the two-phase solvent system composed of ethyl acetate/n-butanol/water (13:3:10, v/v/v) was used for HSCCC separation. A total of 27 mg of forsythoside B, 41 mg of verbascoside, 29 mg of alyssonoside, 23 mg of isoverbascoside, and 13 mg of leucosceptoside B with purities of 97.7, 99.2, 99.5, 99.3, and 97.3%, respectively, were obtained in a one-step separation within 4 h from 150 mg of crude extract. The recoveries of the five PhGs after MR-HSCCC separation were 74.5, 76.5, 72.5, 76.4, and 77.0%, respectively. The chemical structures of all five compounds were identified by (1) H and (13) C NMR spectroscopy.

  2. Preparative isolation and purification of urolithins from the intestinal metabolites of pomegranate ellagitannins by high-speed counter-current chromatography.

    PubMed

    Zhao, Wenhua; Wang, Yuji; Hao, Weijia; Yang, Hua; Song, Xueying; Zhao, Ming; Peng, Shiqi

    2015-05-15

    Urolithins were separated from the intestinal metabolites of pomegranate ellagitannins by high-speed counter current chromatography in two steps using two solvent systems composed of n-hexane-ethyl acetate-methanol-acetic acid-water (2.5:2:0.25:5, v/v/v/v/v) and n-hexane-ethyl acetate-methanol-acetic acid-water (2.5:0. 8:0.25:5, v/v/v/v/v) for the first time. Each injection of 100mg extract yielded 21mg of pure urolithin A and 10mg of pure urolithin B. High-performance liquid chromatography analyses revealed that the purity of urolithin A and urolihtin B was over 98.5%. The structures of urolithin A and urolitihn B were identified by high resolution-MS, NMR and single crystal x-ray analysis. Urolithins reduced the oxidative stress status in colon cancer by decreasing the intracellular ROS and malondialdehyde levels, and increasing SOD activity in H2O2 treated Caco-2 cells.

  3. Efficient Preparation of Streptochlorin from Marine Streptomyces sp. SYYLWHS-1-4 by Combination of Response Surface Methodology and High-Speed Counter-Current Chromatography.

    PubMed

    Li, Lin; He, Shan; Ding, Lijian; Yuan, Ye; Zhu, Peng; Epstein, Slava; Fan, Jianzhong; Wu, Xiaokai; Yan, Xiaojun

    2016-01-01

    Since first isolated from the lipophilic extract of Streptomyces sp. SF2583, streptochlorin, has attracted a lot of attention because of its various pharmacological properties, such as antibiotic, antiallergic, antitumor, and anti-inflammatory activities. For the efficient preparation of streptochlorin from a producing strain Streptomyces sp. SYYLWHS-1-4, we developed a combinative method by using response surface methodology (RSM) and high-speed counter-current chromatography (HSCCC). In the fermentation process, we used RSM to optimize the condition for the efficient accumulation of streptochlorin, and the optimal parameters were: yeast extract 1.889 g/L, soluble starch 8.636 g/L, K₂HPO₄ 0.359 g/L, CaCl₂ 2.5 g/L, MgSO₄ 0.625 g/L, marine salt 25 g/L, medium volume 50%, initial pH value 7.0, temperature 27.5 °C, which enhanced streptochlorin yield by 17.7-fold. During the purification process, the preparative HSCCC separation was performed using a petroleum ether-ethyl acetate-methanol-water (9:0.8:5:5, v/v/v/v) biphasic solvent system, where 300 mg of crude sample yielded 16.5 mg streptochlorin with over 95% purity as determined by UPLC. Consequently, the combination method provided a feasible strategy for highly effective preparation of streptochlorin, which ensured the supply of large amounts of streptochlorin for in vivo pharmacological assessments or other requirements. PMID:27240330

  4. Preparative isolation and purification of lignans from Justicia procumbens using high-speed counter-current chromatography in stepwise elution mode.

    PubMed

    Zhou, Peijuan; Luo, Qijun; Ding, Lijian; Fang, Fang; Yuan, Ye; Chen, Juanjuan; Zhang, Jinrong; Jin, Haixiao; He, Shan

    2015-04-20

    Lignans, which are recognized as main constituents in Justicia procumbens, have attracted considerable attention due to their pharmacological activities, including antitumor, anti-hepatitic, cytotoxic, anti-microbial, and anti-virus properties. Preparative high-speed counter-current chromatography (HSCCC) was successfully applied to the isolation and purification of four lignans (justicidin B (1), justicidin A (2), 6'-hydroxyjusticidin C (3) and lignan J1 (4)) from J. procumbens using stepwise elution with a pair of two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water at (1.3:1:1.3:1, v/v) and (2.5:1:2.5:1, v/v). The preparative HSCCC separation was performed on 300 mg of crude sample yielding compounds 1 (19.7 mg), 2 (9.86 mg), 3 (11.26 mg), and 4 (2.54 mg) in a one-step separation, with purities over 95% as determined by HPLC. The structures of these compounds were identified by MS, 1H-NMR and 13C-NMR. This is the first report on the application of HSCCC to the efficient separation of lignans from J. procumbens.

  5. Isolation and purification of salvianolic acid A and salvianolic acid B from Salvia miltiorrhiza by high-speed counter-current chromatography and comparison of their antioxidant activity.

    PubMed

    Sun, Yinshi; Zhu, Haifang; Wang, Jianhua; Liu, Zhengbo; Bi, Jianjie

    2009-03-15

    Water-soluble salvianolic acid A (Sal A) and salvianolic acid B (Sal B) were successfully isolated and purified from the crude extract of Salvia miltiorrhiza by high-speed counter-current chromatography (HSCCC). The solvent system was n-hexane-ethyl acetate-methanol-water (3:6:6:10, v/v/v/v). 4.27 mg of Sal A and 32.09 mg of Sal B were obtained from 260 mg of the crude sample. The purities of Sal A and Sal B were 96.67% and 97.43%, respectively. Their structures were identified by (1)H NMR and (13)C NMR. Antioxidant activities of Sal A and Sal B were also evaluated and compared by the methods of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS(+)) radical cation decolourisation assay. Both Sal A and Sal B showed high radical scavenging activities with their EC(50) values being 1.43+/-0.09 and 1.81+/-0.01 microg/ml in DPPH radical method. The ABTS results showed that Sal A and Sal B exhibited high total antioxidant activities, their EC(50) values were 1.35+/-0.00 and 1.43+/-0.01 microg/ml, respectively.

  6. Preparative Isolation of Two Prenylated Biflavonoids from the Roots and Rhizomes of Sinopodophyllum emodi by Sephadex LH-20 Column and High-Speed Counter-Current Chromatography.

    PubMed

    Sun, Yan-Jun; Pei, Li-Xin; Wang, Kai-Bo; Sun, Yin-Shi; Wang, Jun-Min; Zhang, Yan-Li; Gao, Mei-Ling; Ji, Bao-Yu

    2015-12-23

    Two prenylated biflavonoids, podoverines B-C, were isolated from the dried roots and rhizomes of Sinopodophyllum emodi using a Sephadex LH-20 column (SLHC) and high-speed counter-current chromatography (HSCCC). The 95% ethanol extract was partitioned with ethyl acetate in water. Target compounds from the ethyl acetate fraction were further enriched and purified by the combined application of SLHC and HSCCC. n-Hexane-ethyl acetate-methanol-water (3.5:5:3.5:5, v/v) was chosen as the two phase solvent system. The flow rate of mobile phase was optimized at 2.0 mL·min(-1). Finally, under optimized conditions, 13.8 mg of podoverine B and 16.2 mg of podoverine C were obtained from 200 mg of the enriched sample. The purities of podoverines B and C were 98.62% and 99.05%, respectively, as determined by HPLC. For the first time, podoverins B and C were found in the genus Sinopodophyllum. Their structures were determined by spectroscopic methods (HR-ESI-MS, ¹H-NMR, (13)C-NMR, HSQC, HMBC). Their absolute configurations were elucidated by comparison of their experimental and calculated ECD spectra. The cytotoxic activities were evaluated against MCF-7 and HepG2 cell lines. The separation procedures proved to be practical and economical, especially for trace prenylated biflavonoids from traditional Chinese medicine.

  7. Isolation of C-glycosylflavonoids with α-glucosidase inhibitory activity from Passiflora bogotensis Benth by gradient high-speed counter-current chromatography.

    PubMed

    Costa, Geison Modesti; Cárdenas, Paola Andrea; Gazola, Andressa Córneo; Aragón, Diana Marcela; Castellanos, Leonardo; Reginatto, Flávio Henrique; Ramos, Freddy Alejandro; Schenkel, Eloir Paulo

    2015-05-15

    In this study, we applied a gradient High-Speed Counter-Current Chromatography (HSCCC) method that allowed, by direct injection of an aqueous crude extract of the leaves of Passiflora bogotensis, the successful isolation of six flavonoids in a single run, with purity of each compound higher than 81%. This separation enabled the isolation of two new flavonoid glycosides, apigenin-6-C-α-l-rhamnopyranosyl-(1→2)-(6″-O-acetyl)-β-d-glucopyranoside (2) and luteolin-6-C-α-l-rhamnopyranosyl-(1→2)-(6″-O-acetyl)-β-d-glucopyranoside (4), and four known ones, isovitexin (1), isoorientin (3), isovitexin-2″-O-rhamnoside (5) and isoorientin-2″-O-rhamnoside (6). The structures of the isolated compounds were identified by HPLC-DAD, LC-MS, (1)H and (13)C NMR and comparison with literature data. The inhibitory activities of all of these compounds were evaluated in vitro on α-glucosidase from S. cerevisiae, and the IC50 was determinate. This is the first study concerning the chemical composition and biological activity of Passiflora bogotensis. PMID:25864011

  8. Combined microwave-assisted extraction and high-speed counter-current chromatography for separation and purification of xanthones from Garcinia mangostana.

    PubMed

    Fang, Lei; Liu, Yuqin; Zhuang, Huiyong; Liu, Wei; Wang, Xiao; Huang, Luqi

    2011-10-15

    A microwave-assisted extraction (MAE) method is presented for the extraction of xanthones, α-mangostin and γ-mangostin from Garcinia mangostana. The MAE conditions including extraction temperature, liquid/solid ratio, extraction time and concentration of ethanol were optimized with an orthogonal test, and 5 g sample was extracted with the optimized conditions. The crude extraction of MAE was successfully isolated and purified by high-speed counter-current chromatography (HSCCC) with a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-water (0.8:0.8:1:0.6, v/v) in one-step separation. The separation yielded 75 mg of α-mangostin at 98.5% purity, and 16 mg of γ-mangostin at 98.1% purity from 360 mg crude extract of G. mangostana in less than 7h. The purity of the two xanthones was determined by HPLC. Their structures were further identified by ESI-MS, (1)H NMR and (13)C NMR.

  9. Preparative separation and purification of four cis-trans isomers of coumaroylspermidine analogs from safflower by high-speed counter-current chromatography.

    PubMed

    Li, Wen-Cong; Wang, Xiao-Yan; Lin, Peng-Cheng; Hu, Na; Zhang, Qiu-Long; Suo, You-Rui; Ding, Chen-Xu

    2013-11-01

    High-speed counter-current chromatography (HSCCC) was successfully applied for the first time to isolate and purify four cis-trans isomers of coumaroylspermidine analogs from Safflower. HSCCC separation was achieved with a two-phase solvent system composed of chloroform-methanol-water (1:1:1, v/v/v) with the upper phase as the mobile phase. In a single run, a total of 1.3mg of N(1), N(5), N(10)-(E)-tri-p-coumaroylspermidine (EEE), 4.4mg of N(1)(E)-N(5)-(Z)-N(10)-(E)-tri-p-coumaroylspermidine (EZE), 7.2mg of N(1)(Z)-N(5)-(Z)-N(10)-(E)-tri-p-coumaroylspermidine (ZZE), and 11.5mg of N(1),N(5),N(10)-(Z)-tri-p-coumaroylspermidine (ZZZ) were obtained from 100mg of crude sample. High Performance Liquid Chromatography (HPLC) analysis showed that the purities of these four components are 95.5%, 98.1%, 97.5% and 96.2%, respectively. The chemical structures were identified by ESI-MS, (1)H NMR and (13)C NMR. PMID:24055753

  10. [Isolation and preparation of an imidazole alkaloid from radix radix of Aconitum pendulum Busch by semi-preparative high-speed counter-current chromatography].

    PubMed

    Liu, Yongling; Chen, Tao; Chen, Chen; Zou, Denglang; Li, Yulin

    2014-05-01

    Aconitum pendulum Busch is rich C19 diterpenoid alkaloids, but there is no report of imidazole alkaloid in Aconitum pendulum Busch. In this study, an imidazole alkaloid named 1H-imidazole-2-carboxylic acid, butyl ester (ICABE) was successfully separated from Aconitum pendulum Busch with semi-preparative high-speed counter-current chromatography (HSCCC). The partition coefficient was measured by HPLC to select the solvent systems for ICABE separation by HSCCC. The separation was performed with a two-phase solvent system composed of n-hexane-chloroform-ethanol-water (10:1 : 13:2, v/v/v/v). The upper phase was used as the stationary phase and the lower phase as the mobile phase. It was operated at a flow rate of 1.8 mL/min. The apparatus was rotated at 850 r/min, and the detection wavelength was set at 230 nm. Under the selected conditions, a high efficiency separation of HSCCC was achieved, and 7.5 mg of ICABE was obtained from 100 mg of the crude sample of Aconitum pendulum in one-step separation within 350 min. The HPLC analysis showed that the purity of the compound was over 98%. The chemical structure was confirmed by UV, 1H-NMR and 13C-NMR. The established method is simple, highly efficient and suitable for large scale separation of ICABE from radix of Aconitum pendulum Busch.

  11. An efficient new method for extraction, separation and purification of psoralen and isopsoralen from Fructus Psoraleae by supercritical fluid extraction and high-speed counter-current chromatography.

    PubMed

    Wang, Xiao; Wang, Yuqiang; Yuan, Jinpeng; Sun, Qinglei; Liu, Jianhua; Zheng, Chengchao

    2004-11-01

    Psoralen and isopsoralen were extracted from Fructus Psoraleae (Psoralea corylitolia L.) by supercritical CO2. The effect of various parameters, i.e., pressure, temperature and sample particle size on yield was investigated with an analytical-scale supercritical fluid extraction (SFE) system to find the optimal conditions. The process was then scaled up by 50 times with a preparative SFE system under the optimized conditions of pressure (26 MPa), temperature (60 degrees C) and a sample particle size of 40-60 mesh. The yield of the preparative SFE was 9.1% and the combined yield of psoralen and isopsoralen was 2.5 mg/g of dry seeds. Psoralen and isopsoralen in the extract were separated and purified by high-speed counter-current chromatography with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (1:0.7:1:0.8, v/v), and the fractions were analyzed by HPLC, MS, 1HNMR and 13C NMR. The structures of the products were further confirmed by comparison with authentic samples (National Institute of the Control of Pharmaceutical and Biological Products, Beijing, China). PMID:15560489

  12. Isolation of α-Amylase Inhibitors from Kadsura longipedunculata Using a High-Speed Counter-Current Chromatography Target Guided by Centrifugal Ultrafiltration with LC-MS.

    PubMed

    Cen, Yin; Xiao, Aiping; Chen, Xiaoqing; Liu, Liangliang

    2016-01-01

    In this study, a high-speed counter-current chromatography (HSCCC) separation method target guided by centrifugal ultrafiltration with high-performance liquid chromatography-mass spectrometry (CU-LC-MS) was proposed. This method was used to analyze α-amylase inhibitors from Kadsura longipedunculata extract. According to previous screening with CU-LC-MS, two screened potential α-amylase inhibitors was successfully isolated from Kadsura longipedunculata extract using HSCCC under the optimized experimental conditions. The isolated two target compounds (with purities of 92.3% and 94.6%) were, respectively, identified as quercetin-3-O-rhamnoside (1) and protocatechuic acid (2) based on the MS, UV, and ¹H-NMR spectrometry data. To verify the inhibition of screened compounds, the inhibitory activities of quercetin-3-O-rhamnoside (1) and protocatechuic acid (2) on α-amylase were tested, and it demonstrated that the experimental IC50 values of quercetin-3-O-rhamnoside (1) and protocatechuic acid (2) were 28.8 and 12.5 μmol/L. These results proved that the hyphenated technique using CU-LC-MS and HSCCC was a rapid, competent, and reproductive method to screen and separate potential active compounds, like enzyme inhibitors from the extract of herbal medicines. PMID:27617987

  13. Preparative separation of sulfur-containing diketopiperazines from marine fungus Cladosporium sp. using high-speed counter-current chromatography in stepwise elution mode.

    PubMed

    Gu, Binbin; Zhang, Yanying; Ding, Lijian; He, Shan; Wu, Bin; Dong, Junde; Zhu, Peng; Chen, Juanjuan; Zhang, Jinrong; Yan, Xiaojun

    2015-01-09

    High-speed counter-current chromatography (HSCCC) was successively applied to the separation of three sulfur-containing diketopiperazines (DKPs) (including two new compounds cladosporin A (1) and cladosporin B (3), and a known compound haematocin (2)) from a marine fungus Cladosporium sp. The two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water at (1:1:1:1, v/v) and (2:1:2:1, v/v), in stepwise elution mode, was used for HSCCC. The preparative HSCCC separation was performed on 300 mg of crude sample yielding 26.7 mg of compound 3 at a purity of over 95%, 53.6 mg of a mixture of compounds 1 and 2, which was further separated by preparative-HPLC yielding 14.3 mg of compound 1 and 25.4 mg of compound 2 each at a purity of over 95%. Their structures were established by spectroscopic methods. The sulfur-containing DKPs suppressed the proliferation of hepatocellular carcinoma cell line HepG2. The present work represents the first application of HSCCC in the efficient preparation of marine fungal natural products.

  14. Fractionation of Gallotannins from mango (Mangifera indica L.) kernels by high-speed counter-current chromatography and determination of their antibacterial activity.

    PubMed

    Engels, Christina; Gänzle, Michael G; Schieber, Andreas

    2010-01-27

    High-speed counter-current chromatography was applied to the separation of gallotannins from mango (Mangifera indica L.) kernels. The kernels were defatted and subsequently extracted with aqueous acetone [80% (v/v)]. The crude extract was purified by being partitioned against ethyl acetate. A hexane/ethyl acetate/methanol/water solvent system [0.5:5:1:5 (v/v/v/v)] was used in the head-to-tail mode to elute tannins according to their degree of galloylation (tetra-O-galloylglucose to deca-O-galloylglucose). The compounds were characterized using liquid chromatography and mass spectrometry in the negative ionization mode. Purities ranged from 72% (tetra-O-galloylglucose) to 100% (octa-O-galloylglucose). The iron binding capacity of gallotannins was dependent on the number of galloyl groups in the molecule, with a larger capacity at lower degrees of galloylation. The minimum inhibitory concentration against Bacillus subtilis did not change among the different gallotannins tested and was in the range of 0.05-0.1 g/L in Luria-Bertani broth but up to 20 times higher in media containing more iron and divalent cations.

  15. Numerical study of turbulence-influence mechanism on arc characteristics in an air direct current circuit breaker

    NASA Astrophysics Data System (ADS)

    Wu, Mingliang; Yang, Fei; Rong, Mingzhe; Wu, Yi; Qi, Yang; Cui, Yufei; Liu, Zirui; Guo, Anxiang

    2016-04-01

    This paper focuses on the numerical investigation of arc characteristics in an air direct current circuit breaker (air DCCB). Using magneto-hydrodynamics (MHD) theory, 3D laminar model and turbulence model are constructed and calculated. The standard k-epsilon model is utilized to consider the turbulence effect in the arc chamber of the DCCB. Several important phenomena are found: the arc column in the turbulence-model case is more extensive, moves much more slowly than the counterpart in the laminar-model case, and shows stagnation at the entrance of the chamber, unlike in the laminar-model case. Moreover, the arc voltage in the turbulence-model case is much lower than in the laminar-model case. However, the results in the turbulence-model case show a much better agreement with the results of the breaking experiments under DC condition than in the laminar-model case, which is contradictory to the previous conclusions from the arc researches of both the low-voltage circuit breaker and the sulfur hexafluoride (SF6) nozzle. First, in the previous air-arc research of the low-voltage circuit breaker, it is assumed that the air plasma inside the chamber is in the state of laminar, and the laminar-model application gives quite satisfactory results compared with the experiments, while in this paper, the laminar-model application works badly. Second, the turbulence-model application in the arc research of the SF6-nozzle performs much better and gives higher arc voltage than the laminar-model application does, whereas in this paper, the turbulence-model application predicts lower arc voltage than the laminar-model application does. Based on the analysis of simulation results in detail, the mechanism of the above phenomena is revealed. The transport coefficients are strongly changed by turbulence, which will enhance the arc diffusion and make the arc volume much larger. Consequently, the arc appearance and the distribution of Lorentz force in the turbulence-model case

  16. The perfect ash-storm: large-scale Pyroclastic Density Current experiments reveal highly mobile, self-fluidising and air-cushioned flow transport regime

    NASA Astrophysics Data System (ADS)

    Lube, G.; Cronin, S. J.; Breard, E.; Valentine, G.; Bursik, M. I.; Hort, M. K.; Freundt, A.

    2013-12-01

    We report on the first systematic series of large-scale Pyroclastic Density Current (PDC) experiments using the New Zealand PDC Generator, a novel international research facility in Physical Volcanology recently commissioned at Massey University. Repeatable highly energetic and hot PDCs are synthesized by the controlled ';eruption column-collapse' of up to 3500 kg of homogenously aerated Taupo ignimbrite material from a 15 m-elevated hopper onto an instrumented inclined flume. At discharge rates between 250-1300 kg/s and low- to moderate gas injection rates (yielding initial solids concentration of 15-70 vol%) channelized gas-particle mixture flows life-scaled to dense PDCs can be generated. The flow fronts of the currents reach velocities of up to 9.5 m/s over their first 12 m of travel and rapidly develop strong vertical density stratification. The PDCs typically form a highly mobile, <60 cm-thick dense and channel-confined underflow, with an overriding dilute and turbulent ash cloud surge that also laterally escapes the flume boundaries. Depending on the PDC starting conditions underflows with 1-45 vol% solids concentration are formed, while the upper surge contains <<1 vol.% solids. A characteristic feature of the underflow is the occurrence of 'ignitive' front breakouts, producing jetted lobes that accelerate outward from the flow front, initially forming a lobe-cleft structure, followed by segregation downslope into multiple flow pulses. Depending on initial solids concentration and discharge rate, stratified, dune-bedded and inversely graded bedforms are created whose thicknesses are remarkably uniform along the medial to distal runout path characterising highly mobile flow runout. Along with high-speed video footage we present time-series data of basal arrays of load- and gas-pore pressure transducers to characterise the mobile dense underflows. Data shows that the PDCs are comprised of a turbulent coarse-grained and air-ingesting front with particle

  17. Ozone generation by negative direct current corona discharges in dry air fed coaxial wire-cylinder reactors

    SciTech Connect

    Yehia, Ashraf; Mizuno, Akira

    2013-05-14

    An analytical study was made in this paper for calculating the ozone generation by negative dc corona discharges. The corona discharges were formed in a coaxial wire-cylinder reactor. The reactor was fed by dry air flowing with constant rates at atmospheric pressure and room temperature, and stressed by a negative dc voltage. The current-voltage characteristics of the negative dc corona discharges formed inside the reactor were measured in parallel with concentration of the generated ozone under different operating conditions. An empirical equation was derived from the experimental results for calculating the ozone concentration generated inside the reactor. The results, that have been recalculated by using the derived equation, have agreed with the experimental results over the whole range of the investigated parameters, except in the saturation range for the ozone concentration. Therefore, the derived equation represents a suitable criterion for expecting the ozone concentration generated by negative dc corona discharges in dry air fed coaxial wire-cylinder reactors under any operating conditions in range of the investigated parameters.

  18. Optimisation of air cooled, open-cathode fuel cells: Current of lowest resistance and electro-thermal performance mapping

    NASA Astrophysics Data System (ADS)

    Meyer, Quentin; Ronaszegi, Krisztian; Pei-June, Gan; Curnick, Oliver; Ashton, Sean; Reisch, Tobias; Adcock, Paul; Shearing, Paul R.; Brett, Daniel J. L.

    2015-09-01

    Selecting the ideal operating point for a fuel cell depends on the application and consequent trade-off between efficiency, power density and various operating considerations. A systematic methodology for determining the optimal operating point for fuel cells is lacking; there is also the need for a single-value metric to describe and compare fuel cell performance. This work shows how the 'current of lowest resistance' can be accurately measured using electrochemical impedance spectroscopy and used as a useful metric of fuel cell performance. This, along with other measures, is then used to generate an 'electro-thermal performance map' of fuel cell operation. A commercial air-cooled open-cathode fuel cell is used to demonstrate how the approach can be used; in this case leading to the identification of the optimum operating temperature of ∼45 °C.

  19. Dynamics of the microstructure of current channels and the generation of high-energy electrons in nanosecond discharges in air

    SciTech Connect

    Karelin, V. I.; Trenkin, A. A. Fedoseev, I. G.

    2015-12-15

    The results of the three-dimensional numerical simulation of the dynamics of the microstructure of high-voltage nanosecond discharges in air at atmospheric pressure are presented. It is established that the fast (at a time of ≈10 ns) broadening and significant decrease in the gas concentration in the microchannels occur as a result of the ohmic heating of microchannels with the diameter of 1–30 μm. It was shown that the broadening of microchannels in a nanosecond diffusive discharge provides an increase in the ratio of the electric field strength to the gas concentration in microchannels to values sufficient for the generation highenergy electron beams and X-ray bremsstrahlung in them. Features of the dynamics of the system of microchannels and its effect on the efficiency of the generation of high-energy electrons in discharges developing in the microstructuring regime of the current channels are considered.

  20. A Review of the Current Geographic Distribution of and Debate Surrounding Electronic Cigarette Clean Air Regulations in the United States

    PubMed Central

    Kadowaki, Joy; Vuolo, Mike; Kelly, Brian C.

    2014-01-01

    In this article, we present the results of a systematic review of state, county, and municipal restrictions on the use of electronic cigarettes (e-cigarettes) in public spaces within the United States, alongside an overview of the current legal landscape. The lack of federal guidance leaves lower-level jurisdictions to debate the merits of restrictions on use in public spaces without sufficient scientific research. As we show through a geographic assessment of restrictions, this has resulted in an inconsistent patchwork of e-cigarette use bans across the United States of varying degrees of coverage. Bans have emerged over time in a manner that suggests a “bottom up” diffusion of e-cigarette clean air policies. Ultimately, the lack of clinical and scientific knowledge on the risks and potential harm reduction benefits has led to precautionary policymaking, which often lacks grounding in empirical evidence and results in spatially uneven diffusion of policy. PMID:25463920

  1. Combined current and temperature mapping in an air-cooled, open-cathode polymer electrolyte fuel cell under steady-state and dynamic conditions

    NASA Astrophysics Data System (ADS)

    Meyer, Q.; Ronaszegi, K.; Robinson, J. B.; Noorkami, M.; Curnick, O.; Ashton, S.; Danelyan, A.; Reisch, T.; Adcock, P.; Kraume, R.; Shearing, P. R.; Brett, D. J. L.

    2015-11-01

    In situ diagnostic techniques provide a means of understanding the internal workings of fuel cells so that improved designs and operating regimes can be identified. Here, for the first time, a combined current density and temperature distributed measurement system is used to generate an electro-thermal performance map of an air-cooled, air-breathing polymer electrolyte fuel cell stack operating in an air/hydrogen cross-flow configuration. Analysis is performed in low- and high-current regimes and a complex relationship between localised current density, temperature and reactant supply is identified that describes the way in which the system enters limiting performance conditions. Spatiotemporal analysis was carried out to characterise transient operations in dead-ended anode/purge mode which revealed extensive current density and temperature gradients.

  2. Isolation of antioxidants from Psoralea corylifolia fruits using high-speed counter-current chromatography guided by thin layer chromatography-antioxidant autographic assay.

    PubMed

    Xiao, Guodong; Li, Guowen; Chen, Liang; Zhang, Zijia; Yin, Jun-Jie; Wu, Tao; Cheng, Zhihong; Wei, Xiaohui; Wang, Zhengtao

    2010-08-20

    A combinative method using high-speed counter-current chromatography (HSCCC) and thin layer chromatography (TLC) as an antioxidant autographic assay was developed to separate antioxidant components from the fruits of Psoralea corylifolia. Under the guidance of TLC bioautography, eight compounds including five flavonoids and three coumarins were successfully separated from the fruits of P. corylifolia by HSCCC with an optimized two-phase solvent system, n-hexane-ethyl acetate-methanol-water (1:1.1:1.3:1, v/v/v/v). The separation produced 5.91mg psoralen, 6.26mg isopsoralen, 3.19mg psoralidin, 0.92mg corylifol A, and 2.43mg bavachinin with corresponding purities of 99.5, 99.8, 99.4, 96.4, and 99.0%, as well as three sub-fractions, in a single run from 250mg ethyl acetate fraction of P. corylifolia extract. Following an additional clean-up step by preparative TLC, 0.4mg 8-prenyldaidzein (purity 91.7%), 4.18mg neobavaisoflavone (purity 97.4%) and 4.36mg isobavachalcone (purity 96.8%) were separated from the three individual sub-fractions. The structures of the isolated compounds were identified by (1)H NMR and (13)C NMR. The results of antioxidant activity estimation by electron spin resonance (ESR) method showed that psoralidin was the most active antioxidant with an IC50 value of 44.7microM. This is the first report on simultaneous separation of eight compounds from P. corylifolia by HSCCC.

  3. [Preparative isolation and purification of five non-volatile compounds from Fructus caryophylli and Flos caryophylli by high-speed counter-current chromatography].

    PubMed

    Gao, Lu; Yu, Bo; Yang, Hong

    2011-11-01

    A high-speed counter-current chromatographic (HSCCC) method was successfully developed for the isolation of three non-volatile compounds from Fructus Caryophylli and two chromone compounds from Flos Caryophylli. The optimum separation solution systems included system A (n-hexane-ethyl acetate-methanol-water (5:8:6: 13, v/v/v/v) and system B (n-hexane-ethyl acetate-methanol-water (5: 8: 9: 10, v/v/v/v). The upper phase of the system A was used as the stationary phase, and the lower phases of the systems A and B as the mobile phases were operated at a flow of 1.2 mL/min, while the apparatus rotated at 880 r/min. The 12.3 mg of ellagic acid, 9.6 mg of rhamnetin, 17.2 mg of quercetin were successfully purified from 70 mg of the crude extract of Fructus Caryophylli by a two-step separation. In the same way, 10.2 mg of 5,7-dimethoxy-2-methylchromone, 8.6 mg of 5,7-dimethoxy-2,6-dimethyl-chromone were purified from 50 mg of the crude extract of Flos Caryophylli. The purities of the compounds were all over 96% as determined by high performance liquid chromatography (HPLC). The five compounds were indentified by mass spectrometry (MS), 1H-nuclear magnetic resonance (NMR) and 13C-NMR. The results indicate that HSCCC is a powerful technique for the purification of non-volatile compounds from different parts of Eugenia caryophylla Thunb.

  4. Purification of patulin from Penicillium expansum culture: high-speed counter-current chromatography (HSCCC) versus preparative high-performance liquid chromatography (prep-HPLC).

    PubMed

    He, J; Tsao, R; Yang, R; Zhou, T

    2009-01-01

    Patulin is a mycotoxin produced by species of Penicillium and Aspergillus and is toxic to a wide range of organisms, including humans and livestock. To produce large amount of pure patulin for research purposes, high-speed counter-current chromatography (HSCCC) and preparative high-performance liquid chromatography (prep-HPLC) were applied to the purification of patulin. Apple juice was inoculated with P. expansum and containing 0.5 mg patulin per ml was used as a starting material for separation. For HSCCC, a biphasic solvent system consisted of ethyl acetate-hexane-pH 4 acetic acid (7.5:2.5:10, v/v/v) was used. For prep-HPLC, the separation was carried out in a C18 reversed-phase preparative column with a mobile phase containing acetonitrile-pH 4 acetic acid (5:95, v/v). Fractions containing patulin were collected and analysed by analytical HPLC and identified by congruent retention time and ultraviolet/visible (UV-VIS) spectrum of the standard. The structure of the purified patulin was confirmed by mass spectrometry and nuclear magnetic resonance. HSCCC produced 21.9 mg of patulin from 50 ml apple juice culture whereas the prep-HPLC yielded 18.1 mg. HSCCC also produced purer patulin than the prep-HPLC (98.6 versus 96.3%) and higher recovery (86.2 versus 71.3%). In addition, the HSCCC method is advantageous for its lower cost and a simpler procedure compared with the prep-HPLC. This one-step HSCCC method can potentially provide a simple, effective and environmentally friendly tool for obtaining gram-level pure patulin for toxicology, detoxification and many other patulin-related studies.

  5. Preparative isolation and purification of flavone compounds from sophora japonica L. by high-speed counter-current chromatography combined with macroporous resin column separation.

    PubMed

    Sun, Ailing; Sun, Qinghua; Liu, Renmin

    2007-05-01

    High-speed counter-current chromatography combined with macroporous resin column separation was applied to the isolation and purification of genistein-7,4'-di-O-beta-D-glucoside (I), genistein-7-O-beta-D-glucopyranoside-4'-O-[(alpha-L-rhamnopyransoyl)-(1-2)-beta-D-glucopyranoside] (II), kaempferol-3-O-beta-D-sophoroside(III), quercetin-3-O-beta-L-ramnopyranosyl-(1 - 6)-beta-D-glucopyranoside (IV), genistein-4'-beta-L-rhamnopyransoyl-(1 - 2)-alpha-D-glucopyranoside (V), and kaempferol-3-O-beta-L-ramnopyranosyl-(1 - 6)-beta-D-glucopyranoside (VI) from the Chinese medicinal herb Sophora japonica L. The crude extracts from the pericarps of Sophora japonica L. were pre-separated on a D-101 macroporous resin column and divided into two parts as sample 1 and sample 2. An 80-mg portion of sample 1 was separated by using n-butanol-acetic acid (1%) (5:5, v/v) as the two-phase solvent system and yielded 30.1 mg of compound I, 23.3 mg of compound II. A 120 mg portion of sample 2 was separated by using ethyl acetate-n-butanol-acetic acid (1%) (5:0.8:5, v/v) as the two-phase solvent system and yielded 5.5 mg of compound III, 31.7 mg of compound IV, 37.4 mg of compound V, and 6.2 mg of compound VI. The purities of compounds I, II, III, IV, V, and VI were 98.7, 98.2, 97.8, 98.5, 99.3, and 98.9%, respectively, as determined by HPLC. The chemical structures of these components were identified by 1H-NMR and 13C-NMR. PMID:17566335

  6. Lutein in selected Canadian crops and agri-food processing by-products and purification by high-speed counter-current chromatography.

    PubMed

    Tsao, Rong; Yang, Raymond

    2006-04-21

    This study mainly focused on lutein content in several selected crops grown in southern Ontario, Canada. Marigold flower, a good rotation crop for the control of nematodes in tobacco fields was found to contain 0.77% lutein (after saponification, on dry basis). A high-speed counter-current chromatography (HSCCC) method using a two-phase solvent system consisting of hexane-ethanol-water (6:4.5:1.5, v/v/v) was developed for the purification of lutein from the saponification mixture of marigold flower extract. The purity of lutein prepared using this HSCCC method was 97%. Free lutein was found to be the predominant form in three squash varieties, and it was mostly found in the peel rather than the commonly consumed flesh. Sweet Mamma, Buttercup and Pepper squash varieties contained 25.4, 18.4 and 30.1mg/100g fresh weigh (FW) of lutein in the peels, respectively. These concentrations were significantly higher than that in spinach and kale (3.7 and 12.3 mg/100 g FW). beta-Carotene was found most in the peel of Sweet Mamma squash at 13.6 mg/100g FW, whereas it was below 2mg/100g FW in all other samples. Cooking increased extractable free lutein by 22-65% in squash peels. Lutein in Yukon Gold potato was at ca. 0.4 mg/100 g FW. Certain Yukon Gold was also found to contain violaxanthin (0.35 mg/100 g FW). Structures of lutein, beta-carotene and violaxanthin were identified by LC-atmospheric pressure chemical ionization MS in positive ion mode, and by comparing the retention time and UV-vis spectral data with standards. Results from this study suggest the selected crops and agri-food industrial processing by-products of these can be a good source of free lutein.

  7. Statistical Short-Range Guidance for Peak Wind Speed Forecasts on Kennedy Space Center/Cape Canaveral Air Force Station: Phase I Results

    NASA Technical Reports Server (NTRS)

    Lambert, Winifred C.; Merceret, Francis J. (Technical Monitor)

    2002-01-01

    This report describes the results of the ANU's (Applied Meteorology Unit) Short-Range Statistical Forecasting task for peak winds. The peak wind speeds are an important forecast element for the Space Shuttle and Expendable Launch Vehicle programs. The Keith Weather Squadron and the Spaceflight Meteorology Group indicate that peak winds are challenging to forecast. The Applied Meteorology Unit was tasked to develop tools that aid in short-range forecasts of peak winds at tower sites of operational interest. A 7 year record of wind tower data was used in the analysis. Hourly and directional climatologies by tower and month were developed to determine the seasonal behavior of the average and peak winds. In all climatologies, the average and peak wind speeds were highly variable in time. This indicated that the development of a peak wind forecasting tool would be difficult. Probability density functions (PDF) of peak wind speed were calculated to determine the distribution of peak speed with average speed. These provide forecasters with a means of determining the probability of meeting or exceeding a certain peak wind given an observed or forecast average speed. The climatologies and PDFs provide tools with which to make peak wind forecasts that are critical to safe operations.

  8. Optical receiver for high-speed communication

    NASA Astrophysics Data System (ADS)

    Mitchell, Paul A.; Grib, Valerie J.

    2010-04-01

    For through-the-air optical communication applications, we present a high speed detector module with high bandwidth and large active area. The detector has achieved a rise time of 220 pS with a full-width-half-max of 420 pS. Data rates are expected to approach 2 GHz. The active area of the input window is 12 mm, giving a large collection surface for through-the-air applications. The detector module includes an integrated power supply having low power consumption. In comparison with other detector technologies, this new detector exceeds the speed of conventional photomultiplier designs by 3 to 5 times. In comparison with microchannel plate detectors, the speed is comparable, but the throughput of the new detector is much higher - tens of microamperes of signal current can be obtained indefinitely. Optical communication applications can be served by two different designs. In the first case, the module utilizes gain based on ordinary secondary emission materials to achieve current gains of 1500. This design is suitable for applications at the limit of the detector's bandwidth where light power is relatively high. In another design, the secondary emission material was changed to diamond film which allows five times higher gain. While the current design uses an ordinary, blue sensitive input light conversion material, higher efficiency materials are in development for signals at longer wavelength.

  9. Investigation of unsaponifiable matter of plant oils and isolation of eight phytosterols by means of high-speed counter-current chromatography.

    PubMed

    Schröder, Markus; Vetter, Walter

    2012-05-11

    Phytosterols are minor components of plant oils. Due to their beneficial effect on human serum cholesterol level, new products supplemented with phytosterols have been marketed. Commercial phytosterol standards are frequently of insufficient purity, very expensive, only available in (semi-) synthetic form or not available at all. For this reason we aimed to explore the unsaponifiable matter of three plant oils (rapeseed oil, linseed oil and olive oil) in order to study their compositions and to purify several phytosterols. We fractionated ∼ 100 mg of the unsaponifiable matter of the plant oils with high-speed counter-current chromatography (HSCCC) by the combination of an enrichment step and a purification step. In the first part (enrichment step) composition of phytosterols, alkanes, fatty alcohols from 14:0 to 30:0 including isomers, 15-nonacosanone and other ketones as well as further minor compounds in the different fractions was studied by GC/MS. By means of the solvent system n-hexane/methanol/aqueous silver nitrate solution (34/24/1, v/v/v) in normal phase mode (tail-to-head) β-sitosterol could be isolated (6.4 mg, purity ≥ 99%) and several phytosterols (e.g. citrostadienol, cycloeucalenol and erythrodiol) could be enriched. Moreover, the fast eluting hydrocarbons squalene and nonacosane as well as the later eluting phytol (pure, 7 mg) and geranyl geraniol could also be efficiently enriched. Suited HSCCC fractions from the three plant oils were merged and re-injected into the HSCCC system (purification step). The HSCCC purification step provided 6.9 mg campesterol (≥ 99%), 2.9 mg brassicasterol (≥ 99%), 0.3mg Δ5-avenasterol (≥ 90%), 9.5mg cycloartenol (≥ 90%), 3.7 mg 24-methylene-cycloartanol (≥ 99%), and ∼ 1mg of an unknown compound (∼ 80%) isolated from rapeseed and linseed oil. Furthermore, the combined HSCCC enrichment and purification of a hydrogenated sterol standard provided two pure phytostanols (campestanol ≥ 99% and sitostanol

  10. Preparative Separation of Phenolic Compounds from Chimonanthus praecox Flowers by High-Speed Counter-Current Chromatography Using a Stepwise Elution Mode.

    PubMed

    Li, Huaizhi; Zhang, Yongqing; Liu, Qian; Sun, Changlei; Li, Jia; Yang, Peng; Wang, Xiao

    2016-01-01

    High-speed counter-current chromatography (HSCCC) has been successfully used for the separation of eight compounds from Chimonanthus praecox flowers. Firstly, the crude extract of Chimonanthus praecox flowers was dissolved in a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-H₂O (5:5:3:7, v/v) and divided into two parts: the upper phase (part I) and the lower phase (part II). Then, HSCCC was applied to separate the phenolic acids from part I and part II, respectively. Considering the broad polarity range of target compounds in part I, a stepwise elution mode was established. Two optimal solvent systems of petroleum ether-ethyl acetate-methanol-H₂O-formic acid (FA) (5:5:3:7:0.02, 5:5:4.3:5.7:0.02, v/v) were employed in this separation. Five phenylpropanoids and two flavonoids were successfully separated from 280 mg of part I, including 8.7 mg of 3,4-dihydroxy benzoic acid (a, 95.3% purity), 10.9 mg of protocatechualdehyde (b, 96.8% purity), 11.3 mg of p-coumaric acid (c, 98.9% purity), 12.2 mg of p-hydroxybenzaldehyde (d, 95.9% purity), 24.7 mg of quercetin (e, 97.3% purity), 33.8 mg of kaempferol (f, 96.8% purity), and 24.6 mg of 4-hydroxylcinnamic aldehyde (g, 98.0% purity). From 300 mg of part II, 65.7 mg of rutin (h, 98.2% purity), 7.5 mg of 3,4-dihydroxy benzoic acid (a, 77.4% purity), and 4.7 mg of protocatechualdehyde (b, 81.6% purity) were obtained using the solvent system EtOAc-n-butanol (n-BuOH)-FA-H₂O (4:1:0.5:5, v/v). The structures of the eight pure compounds were confirmed by electrospray ionization-mass spectrometry (ESI-MS), ¹H-NMR and (13)C-NMR. To the best of our knowledge, compounds a-d and f were the first separated and reported from the Chimonanthus praecox flower extract.

  11. Preparative separation of two subsidiary colors of FD&C Yellow No. 5 (Tartrazine) using spiral high-speed counter-current chromatography◊

    PubMed Central

    Roque, Jose A.; Mazzola, Eugene P.; Ito, Yoichiro

    2014-01-01

    Specifications in the U.S. Code of Federal Regulations for the color additive FD&C Yellow No. 5 (Colour Index No. 19140) limit the level of the tetrasodium salt of 4-[(4',5-disulfo[1,1'-biphenyl]-2-yl)hydrazono]-4,5-dihydro-5-oxo-1-(4-sulfophenyl)-1H-pyrazole-3-carboxylic acid and that of the trisodium salt of 4,4'-[4,5-dihydro-5-oxo-4-[(4-sulfophenyl)hydrazono]-1H-pyrazol-1,3-diyl]bis[benzenesulfonic acid], which are subsidiary colors abbreviated as Pk5 and Pk7, respectively. Small amounts of Pk5 and Pk7 are needed by the U.S. Food and Drug Administration for confirmatory analyses and for development of analytical methods. The present study describes the use of spiral high-speed counter-current chromatography (HSCCC) with the recently introduced highly polar organic/high-ionic strength aqueous solvent systems to separate Pk5 and Pk7 from a sample of FD&C Yellow No. 5 containing ~3.5% Pk5 and ~0.7% Pk7. Multiple ~1.0 g portions of FD&C Yellow No. 5 (totaling 6.4 g dye) were separated, using the upper phase of the solvent system 1-BuOH/EtOHabs/saturated ammonium sulfate/water, 1.7:0.3:1:1, v/v/v/v, as the mobile phase. After applying a specially developed method for removing the ammonium sulfate from the HSCCC-collected fractions, these separations resulted in an enriched mixture (~160 mg) of Pk5 and Pk7 (~46% and ~21%, respectively). Separation of the enriched mixture, this time using the lower phase of that solvent system as the mobile phase, resulted in ~ 61 mg of Pk5 collected in fractions whose purity ranged from 88.0% to 92.7% (by HPLC at 254 nm). Pk7 (20.7 mg, ~83% purity) was recovered from the upper phase of the column content. Application of this procedure also resulted in purifying the major component of FD&C Yellow No. 5 to >99% purity. The separated compounds were characterized by high-resolution mass spectrometry and several 1H and 13C nuclear magnetic resonance spectroscopic techniques (COSY, NOESY, HSQC, and HMBC). PMID:24755184

  12. Preparative Separation of Phenolic Compounds from Chimonanthus praecox Flowers by High-Speed Counter-Current Chromatography Using a Stepwise Elution Mode.

    PubMed

    Li, Huaizhi; Zhang, Yongqing; Liu, Qian; Sun, Changlei; Li, Jia; Yang, Peng; Wang, Xiao

    2016-01-01

    High-speed counter-current chromatography (HSCCC) has been successfully used for the separation of eight compounds from Chimonanthus praecox flowers. Firstly, the crude extract of Chimonanthus praecox flowers was dissolved in a two-phase solvent system composed of petroleum ether-ethyl acetate-methanol-H₂O (5:5:3:7, v/v) and divided into two parts: the upper phase (part I) and the lower phase (part II). Then, HSCCC was applied to separate the phenolic acids from part I and part II, respectively. Considering the broad polarity range of target compounds in part I, a stepwise elution mode was established. Two optimal solvent systems of petroleum ether-ethyl acetate-methanol-H₂O-formic acid (FA) (5:5:3:7:0.02, 5:5:4.3:5.7:0.02, v/v) were employed in this separation. Five phenylpropanoids and two flavonoids were successfully separated from 280 mg of part I, including 8.7 mg of 3,4-dihydroxy benzoic acid (a, 95.3% purity), 10.9 mg of protocatechualdehyde (b, 96.8% purity), 11.3 mg of p-coumaric acid (c, 98.9% purity), 12.2 mg of p-hydroxybenzaldehyde (d, 95.9% purity), 24.7 mg of quercetin (e, 97.3% purity), 33.8 mg of kaempferol (f, 96.8% purity), and 24.6 mg of 4-hydroxylcinnamic aldehyde (g, 98.0% purity). From 300 mg of part II, 65.7 mg of rutin (h, 98.2% purity), 7.5 mg of 3,4-dihydroxy benzoic acid (a, 77.4% purity), and 4.7 mg of protocatechualdehyde (b, 81.6% purity) were obtained using the solvent system EtOAc-n-butanol (n-BuOH)-FA-H₂O (4:1:0.5:5, v/v). The structures of the eight pure compounds were confirmed by electrospray ionization-mass spectrometry (ESI-MS), ¹H-NMR and (13)C-NMR. To the best of our knowledge, compounds a-d and f were the first separated and reported from the Chimonanthus praecox flower extract. PMID:27527132

  13. Preparative separation of two subsidiary colors of FD&C Yellow No. 5 (Tartrazine) using spiral high-speed counter-current chromatography.

    PubMed

    Weisz, Adrian; Ridge, Clark D; Roque, Jose A; Mazzola, Eugene P; Ito, Yoichiro

    2014-05-23

    Specifications in the U.S. Code of Federal Regulations for the color additive FD&C Yellow No. 5 (Color Index No. 19140) limit the level of the tetrasodium salt of 4-[(4',5-disulfo[1,1'-biphenyl]-2-yl)hydrazono]-4,5-dihydro-5-oxo-1-(4-sulfophenyl)-1H-pyrazole-3-carboxylic acid and that of the trisodium salt of 4,4'-[4,5-dihydro-5-oxo-4-[(4-sulfophenyl)hydrazono]-1H-pyrazol-1,3-diyl]bis[benzenesulfonic acid], which are subsidiary colors abbreviated as Pk5 and Pk7, respectively. Small amounts of Pk5 and Pk7 are needed by the U.S. Food and Drug Administration for confirmatory analyses and for development of analytical methods. The present study describes the use of spiral high-speed counter-current chromatography (HSCCC) to separate the closely related minor components Pk5 and Pk7 from a sample of FD&C Yellow No. 5 containing ∼3.5% Pk5 and ∼0.7% Pk7. The separations were performed with highly polar organic/high-ionic strength aqueous two-phase solvent systems that were chosen by applying the recently introduced method known as graphic optimization of partition coefficients (Zeng et al., 2013). Multiple ∼1.0g portions of FD&C Yellow No. 5 (totaling 6.4g dye) were separated, using the upper phase of the solvent system 1-butanol/abs. ethanol/saturated ammonium sulfate/water, 1.7:0.3:1:1, v/v/v/v, as the mobile phase. After removing the ammonium sulfate from the HSCCC-collected fractions, these separations resulted in an enriched dye mixture (∼160mg) of which Pk5 represented ∼46% and Pk7, ∼21%. Separation of the enriched mixture, this time using the lower phase of that solvent system as the mobile phase, resulted in ∼61mg of Pk5 collected in fractions whose purity ranged from 88.0% to 92.7%. Pk7 (20.7mg, ∼83% purity) was recovered from the upper phase of the column contents. Application of this procedure also resulted in purifying the major component of FD&C Yellow No. 5 to >99% purity. The separated compounds were characterized by high-resolution mass

  14. The separation of flavonoids from Pongamia pinnata using combination columns in high-speed counter-current chromatography with a three-phase solvent system.

    PubMed

    Yin, Hao; Zhang, Si; Long, Lijuan; Yin, Hang; Tian, Xinpeng; Luo, Xiongming; Nan, Haihan; He, Sha

    2013-11-01

    The mangrove plant Pongamia pinnata (Leguminosae) is well known as a plant pesticide. Previous studies have indicated that the flavonoids are responsible of the biological activities of the plant. A new high-speed counter-current chromatography (HSCCC) method for the separation of three flavonoids, karanjin (1), pinnatin (2), and pongaflavone (3), from P. pinnata was developed in the present study. The lower and intermediate phase (LP and IP) of a new three-phase solvent system, n-hexane-acetonitrile-dichloromethane-water, at a volume ratio of 5:5:1:5, were used as the stationary phases, while the upper phase (UP) was used as the mobile phase, and the volume ratio between the stationary phases in the CCC column could be tuned by varying the initial pumped volume ratio of the stationary phases. The CCC columns containing all three phases of the solvent system were considered combination columns. According to the theories of combination column, it is possible to optimize the retention time of the target compounds by varying the volume ratio of the stationary phases in the HSCCC combination columns, as well as the suitable volume ratios of the stationary phases for the separation of the target compounds were predicted from the partition coefficients of the compounds in the three-phase solvent system. Then, three HSCCC separations using the combination columns with initial pumped LP:IP volume ratios of 1:0, 0.9:0.1, and 0.7:0.3 were performed separately based on the prediction. Three target compounds were prepared with high purity when the initial pumped volume ratio of the stationary phases was 0.9:0.1. The baseline separation of compounds 2 and 3 was achieved on the combination column with an initial pumped volume ratio of 0.7:0.3. Furthermore, the three experiments clearly demonstrated that the retentions and resolutions of the target compounds increased with an increasing volume ratio of IP, which is consistent with the prediction for the retention times for the

  15. The separation of flavonoids from Pongamia pinnata using combination columns in high-speed counter-current chromatography with a three-phase solvent system.

    PubMed

    Yin, Hao; Zhang, Si; Long, Lijuan; Yin, Hang; Tian, Xinpeng; Luo, Xiongming; Nan, Haihan; He, Sha

    2013-11-01

    The mangrove plant Pongamia pinnata (Leguminosae) is well known as a plant pesticide. Previous studies have indicated that the flavonoids are responsible of the biological activities of the plant. A new high-speed counter-current chromatography (HSCCC) method for the separation of three flavonoids, karanjin (1), pinnatin (2), and pongaflavone (3), from P. pinnata was developed in the present study. The lower and intermediate phase (LP and IP) of a new three-phase solvent system, n-hexane-acetonitrile-dichloromethane-water, at a volume ratio of 5:5:1:5, were used as the stationary phases, while the upper phase (UP) was used as the mobile phase, and the volume ratio between the stationary phases in the CCC column could be tuned by varying the initial pumped volume ratio of the stationary phases. The CCC columns containing all three phases of the solvent system were considered combination columns. According to the theories of combination column, it is possible to optimize the retention time of the target compounds by varying the volume ratio of the stationary phases in the HSCCC combination columns, as well as the suitable volume ratios of the stationary phases for the separation of the target compounds were predicted from the partition coefficients of the compounds in the three-phase solvent system. Then, three HSCCC separations using the combination columns with initial pumped LP:IP volume ratios of 1:0, 0.9:0.1, and 0.7:0.3 were performed separately based on the prediction. Three target compounds were prepared with high purity when the initial pumped volume ratio of the stationary phases was 0.9:0.1. The baseline separation of compounds 2 and 3 was achieved on the combination column with an initial pumped volume ratio of 0.7:0.3. Furthermore, the three experiments clearly demonstrated that the retentions and resolutions of the target compounds increased with an increasing volume ratio of IP, which is consistent with the prediction for the retention times for the

  16. Non-Chemical Stressors and Cumulative Risk Assessment: An Overview of Current Initiatives and Potential Air Pollutant Interactions

    PubMed Central

    Lewis, Ari S.; Sax, Sonja N.; Wason, Susan C.; Campleman, Sharan L.

    2011-01-01

    Regulatory agencies are under increased pressure to consider broader public health concerns that extend to multiple pollutant exposures, multiple exposure pathways, and vulnerable populations. Specifically, cumulative risk assessment initiatives have stressed the importance of considering both chemical and non-chemical stressors, such as socioeconomic status (SES) and related psychosocial stress, in evaluating health risks. The integration of non-chemical stressors into a cumulative risk assessment framework has been largely driven by evidence of health disparities across different segments of society that may also bear a disproportionate risk from chemical exposures. This review will discuss current efforts to advance the field of cumulative risk assessment, highlighting some of the major challenges, discussed within the construct of the traditional risk assessment paradigm. Additionally, we present a summary of studies of potential interactions between social stressors and air pollutants on health as an example of current research that supports the incorporation of non-chemical stressors into risk assessment. The results from these studies, while suggestive of possible interactions, are mixed and hindered by inconsistent application of social stress indicators. Overall, while there have been significant advances, further developments across all of the risk assessment stages (i.e., hazard identification, exposure assessment, dose-response, and risk characterization) are necessary to provide a scientific basis for regulatory actions and effective community interventions, particularly when considering non-chemical stressors. A better understanding of the biological underpinnings of social stress on disease and implications for chemical-based dose-response relationships is needed. Furthermore, when considering non-chemical stressors, an appropriate metric, or series of metrics, for risk characterization is also needed. Cumulative risk assessment research will benefit

  17. Aircraft modifications: Assessing the current state of Air Force aircraft modifications and the implications for future military capability

    NASA Astrophysics Data System (ADS)

    Hill, Owen Jacob

    How prepared is the U.S. Air Force to modify its aircraft fleet in upcoming years? Aircraft modernization is a complex interaction of new and legacy aircraft, organizational structure, and planning policy. This research will take one component of modernization: aircraft modification, and apply a new method of analysis in order to help formulate policy to promote modernization. Departing from previous small-sample studies dependent upon weight as a chief explanatory variable, this dissertation incorporates a comprehensive dataset that was constructed for this research of all aircraft modifications from 1996 through 2005. With over 700 modification programs, this dataset is used to examine changes to the current modification policy using policy-response regression models. These changes include separating a codependent procurement and installation schedule, reducing the documentation requirements for safety modifications, and budgeting for aging aircraft modifications. The research then concludes with predictive models for the F-15 and F-16 along with their replacements: the F-22 and F-35 Joint Strike Fighter.

  18. Comparison of atmospheric air plasmas excited by high-voltage nanosecond pulsed discharge and sinusoidal alternating current discharge

    NASA Astrophysics Data System (ADS)

    Zhang, Shuai; Wang, Wen-chun; Jiang, Peng-chao; Yang, De-zheng; Jia, Li; Wang, Sen

    2013-10-01

    In this paper, atmospheric pressure air discharge plasma in quartz tube is excited by 15 ns high-voltage nanosecond pulsed discharge (HVNPD) and sinusoidal alternating current discharge (SACD), respectively, and a comparison study of these two kinds of discharges is made through visual imaging, electrical characterization, optical detection of active species, and plasma gas temperature. The peak voltage of the power supplies is kept at 16 kV while the pulse repetition rate of nanosecond pulse power supply is 100 Hz, and the frequency of sinusoidal power supply is 10 kHz. Results show that the HVNPD is uniform while the SACD presents filamentary mode. For exciting the same cycles of discharge, the average energy consumption in HVNPD is about 1/13 of the SACD. However, the chemical active species generated by the HVNPD is about 2-9 times than that excited by the SACD. Meanwhile, the rotational and vibrational temperatures have been obtained via fitting the simulated spectrum of N2 (C3Πu → B3Πg, 0-2) with the measured one, and the results show that the plasma gas temperature in the HVNPD remains close to room temperature whereas the plasma gas temperature in the SACD is about 200 K higher than that in HVNPD in the initial phase and continually increases as discharge exposure time goes on.

  19. Characterization of argon direct-current glow discharge with a longitudinal electric field applied at ambient air

    PubMed Central

    Jiang, Weiman; Tang, Jie; Wang, Yishan; Zhao, Wei; Duan, Yixiang

    2014-01-01

    A direct-current-driven plasma jet is developed by applying a longitudinal electric field on the flowing argon at ambient air. This plasma shows a torch shape with its cross-section increased from the anode to the cathode. Comparison with its counterparts indicates that the gas flow plays a key role in variation of the plasma structure and contributes much to enlarging the plasma volume. It is also found that the circular hollow metal base promotes generation of plasma with a high-power volume density in a limited space. The optical emission spectroscopy (OES) diagnosis indicates that the plasma comprises many reactive species, such as OH, O, excited N2, and Ar metastables. Examination of the rotational and vibrational temperature indicates that the plasma is under nonequilibrium condition and the excited species OH(A 2Σ+), O(5P), and N2(C 3Πu) are partly generated by energy transfer from argon metastables. The spatially resolved OES of plasma reveals that the negative glow, Faraday dark space, and positive column are distributed across the gas gap. The absence of the anode glow is attributed to the fact that many electrons in the vicinity of the anode follow ions into the positive column due to the ambipolar diffusion in the flowing gas. PMID:25205176

  20. Air Pollution Exposure and Physical Activity in China: Current Knowledge, Public Health Implications, and Future Research Needs

    PubMed Central

    Lü, Jiaojiao; Liang, Leichao; Feng, Yi; Li, Rena; Liu, Yu

    2015-01-01

    Deteriorating air quality in China has created global public health concerns in regard to health and health-related behaviors. Although emerging environmental regulations address ambient air pollution in China, the level of enforcement and long-term impact of these measures remain unknown. Exposure to air pollution has been shown to lead to multiple adverse health outcomes, including increased rates of heart disease and mortality. However, a lesser-known but increasingly significant concern is the relationship between air pollution and its effects on outdoor exercise. This is especially important in China, which has a culturally rooted lifestyle that encourages participation in outdoor physical activity. This article evaluates the intersection of air pollution and outdoor exercise and provides a discussion of issues related to its public health impact in China, where efforts to promote a healthy lifestyle may be adversely affected by the ambient air pollution that has accompanied rapid economic development and urbanization. PMID:26610539

  1. Air Pollution Exposure and Physical Activity in China: Current Knowledge, Public Health Implications, and Future Research Needs.

    PubMed

    Lü, Jiaojiao; Liang, Leichao; Feng, Yi; Li, Rena; Liu, Yu

    2015-11-20

    Deteriorating air quality in China has created global public health concerns in regard to health and health-related behaviors. Although emerging environmental regulations address ambient air pollution in China, the level of enforcement and long-term impact of these measures remain unknown. Exposure to air pollution has been shown to lead to multiple adverse health outcomes, including increased rates of heart disease and mortality. However, a lesser-known but increasingly significant concern is the relationship between air pollution and its effects on outdoor exercise. This is especially important in China, which has a culturally rooted lifestyle that encourages participation in outdoor physical activity. This article evaluates the intersection of air pollution and outdoor exercise and provides a discussion of issues related to its public health impact in China, where efforts to promote a healthy lifestyle may be adversely affected by the ambient air pollution that has accompanied rapid economic development and urbanization.

  2. Air-sea Energy Transfer at Mesoscale in a Coupled High-resolution Model: Impact of Resolution and Current Feedback

    NASA Astrophysics Data System (ADS)

    Jullien, S.; Colas, F.; Masson, S. G.; Oerder, V.; Echevin, V.; Samson, G.; Crétat, J.; Berthet, S.; Hourdin, C.

    2015-12-01

    Winds are usually considered to force the ocean but recent studies suggested that oceanic mesoscale activity, characterized by eddies, filaments and fronts, could also affect the wind field. These structures feature abrupt changes in sea surface temperature (SST), surface pressure and surface currents that could impact the atmosphere by enhancing/reducing air-sea fluxes, accelerating/decelerating winds, modifying the wind-pressure balance… At this time, the detailed processes associated to such coupling, its intensity and significance remain a matter of research. Here, a state-of-the-art WRF-OASIS-NEMO coupled model is set up over a wide tropical channel (45°S-45°N) at various resolutions: 3/4°, 1/4° and 1/12° in both the ocean and the atmosphere. Several experiments are conducted in forced, partially or fully coupled modes, to highlight the effect of resolution and the role of SST vs. current feedback to energy injection into the ocean and the atmosphere. In strong mesoscale activity regions, a negative wind power input from the atmosphere to the ocean is seen at scales ranging from 100km to more than 1000km. Nonexistent at 3/4°, this negative forcing, acting against oceanic mesoscale activity, is almost twice more important at 1/12° than at 1/4°. In addition, partially coupled simulations, i.e. without current feedback, show that the impact of thermal coupling on this process is very limited. Energy injection to the marine atmospheric boundary layer also features imprints from oceanic mesoscale. Energy injection by scales shorter than 300km represents up to 20% of the total. Finally we show that increasing oceanic resolution, and therefore mesoscale activity, is necessary to resolve the full wind stress spectrum and has an upscaling effect by enhancing atmospheric mesoscale, which is larger scale than in the ocean. Using 1/4°oceanic resolution instead of 1/12° leads to a 50% loss of energy in the atmospheric mesoscale.

  3. Isokinetic air sampler

    DOEpatents

    Sehmel, George A.

    1979-01-01

    An isokinetic air sampler includes a filter, a holder for the filter, an air pump for drawing air through the filter at a fixed, predetermined rate, an inlet assembly for the sampler having an inlet opening therein of a size such that isokinetic air sampling is obtained at a particular wind speed, a closure for the inlet opening and means for simultaneously opening the closure and turning on the air pump when the wind speed is such that isokinetic air sampling is obtained. A system incorporating a plurality of such samplers provided with air pumps set to draw air through the filter at the same fixed, predetermined rate and having different inlet opening sizes for use at different wind speeds is included within the ambit of the present invention as is a method of sampling air to measure airborne concentrations of particulate pollutants as a function of wind speed.

  4. Assessing levels and seasonal variations of current-use pesticides (CUPs) in the Tuscan atmosphere, Italy, using polyurethane foam disks (PUF) passive air samplers.

    PubMed

    Estellano, Victor H; Pozo, Karla; Efstathiou, Christos; Pozo, Katerine; Corsolini, Simonetta; Focardi, Silvano

    2015-10-01

    Polyurethane foam disks (PUF) passive air samplers (PAS) were deployed over 4 sampling periods of 3-5-months (≥ 1 year) at ten urban and rural locations throughout the Tuscany Region. The purpose was to assess the occurrence and seasonal variations of ten current-use pesticides (CUPs). PUF disk extracts were analyzed using GC-MS. The organophosphates insecticides; chlorpyrifos (3-580 pg m(-3)) and chlorpyrifos-methyl (below detection limit - to 570 pg m(-3)) presented the highest levels in air, and showed seasonal fluctuation coinciding with the growing seasons. The relative proportion urban/(urban + rural) ranged from 0.4 to 0.7 showing no differences between urban and rural concentrations. Air back trajectories analysis showed air masses passing over agricultural fields and potentially enhancing the drift of pesticides into the urban sites. This study represents the first information regarding CUPs in the atmosphere of Tuscany region using PAS-PUF disk.

  5. A clean air continuous flow propulsion facility

    NASA Technical Reports Server (NTRS)

    Krauss, R. H.; Mcdaniel, J. C., Jr.

    1992-01-01

    Consideration is given to a contaminant-free, high enthalpy, continuous flow facility designed to obtain detailed code validation measurements of high speed combustion. The facility encompasses uncontaminated air temperature control to within 5 K, fuel temperature control to 2 K, a ceramic flow straightener, drying of inlet air, and steady state continuous operation. The air heating method provides potential for independent control of contaminant level by injection, mixing, and heating upstream. Particular attention is given to extension of current capability of 1250 K total air temperature, which simulates Scramjet enthalpy at Mach 5.

  6. Current Applications of OMI Tropospheric NO2 Data for Air Quality and a Look to the Future

    NASA Technical Reports Server (NTRS)

    Pickering, Kenneth E.; Bucsela, E.; Allen, D.; Prados, A.; Gleason, J.; Kondragunta, S.

    2010-01-01

    Ozone Monitoring Instrument (OMI) Tropospheric NO2 products are being used to enhance the ability to monitor changes in NO2 air quality, update emission inventories, and evaluate regional air quality models. Trends in tropospheric column NO2 have been examined over the eastern United States in relation to emissions changes mandated by regulatory actions. Decreases of 20 to 40 percent over the period 2005 to 2008 were noted, largely in response to major emission reductions at power plants. The OMI data have been used to identify regions in which the opposite trend has been found. We have also used OMI NO2 in efforts to improve emission inventories for NOx emissions from soil. Lightning NOx emissions have been added to CMAQ, the US Environmental Protection Agency's regional air quality model. Evaluation of the resulting NO2 columns in the model is being conducted using the OMI NO2 observations. Community Multiscale Air Quality (CMAQ) together with the OMI NO2 data comprise a valuable tool for monitoring and predicting air quality. Looking to the future, we expect that the combination of Global Ozone Monitoring Experiment-2 (GOME-2) (morning) and OMI (afternoon) data sets obtained through use of the same retrieval algorithms will substantially increase the possibility of successful integration of satellite information into regional air quality forecast models. Farther down the road, we anticipate the Geostationary Coastal and Air Pollution Events (GEO-CAPE) platform to supply data possibly on an hourly basis, allowing much more comprehensive analysis of air quality from space.

  7. Automated high-speed analysis of selected organic compounds in urban air by on-line isotopic dilution cryofocusing gas chromatography/mass spectrometry.

    PubMed

    Davoli, E; Cappellini, L; Maggi, M; Fanelli, R

    1994-11-01

    An automated environmental air monitor has been developed to measure selected organic compounds in urban air. The instrument is based on a cryofocusing-thermal desorption gas chromatographic mass spectrometry technique where the mass spectrometer is a slightly modified residual gas analyzer (RGA). The RGA was chosen as a detector because the whole system must be robust for long periods, with 24-h continuous air monitoring. RCA are extremely simple and seemed the most reliable mass spectrometers for this purpose. Moreover, because they have no physically limited ion source, contamination is considerably reduced, so maintenance intervals are longer.The gas chromatograph is equipped with a computer-controlled six-way sampling valve, with a 100-mL sampling loop and thermal desorption cold trap injector. Environmental air is enriched with an isotopically labeled internal standard in the sampling line. This internal standard is added with a validated, custom-made, permeation tube device. The "on-line" internal standard provides for high quality quantitative data because all variations in instrument sensitivity in cryofocusing or in thermal desorption efficiency are taken into account. High repetition rates (down to 5 min for a full analytical cycle) are obtained with the use of an isothermal gas chromatography program, microbore capillary column, and environmental air sampling during the gas chromatography run.

  8. The impact of shipping emissions on air pollution in the greater North Sea region - Part 1: Current emissions and concentrations

    NASA Astrophysics Data System (ADS)

    Aulinger, A.; Matthias, V.; Zeretzke, M.; Bieser, J.; Quante, M.; Backes, A.

    2016-01-01

    The North Sea is one of the areas with the highest ship traffic densities worldwide. At any time, about 3000 ships are sailing its waterways. Previous scientific publications have shown that ships contribute significantly to atmospheric concentrations of NOx, particulate matter and ozone. Especially in the case of particulate matter and ozone, this influence can even be seen in regions far away from the main shipping routes. In order to quantify the effects of North Sea shipping on air quality in its bordering states, it is essential to determine the emissions from shipping as accurately as possible. Within Interreg IVb project Clean North Sea Shipping (CNSS), a bottom-up approach was developed and used to thoroughly compile such an emission inventory for 2011 that served as the base year for the current emission situation. The innovative aspect of this approach was to use load-dependent functions to calculate emissions from the ships' current activities instead of averaged emission factors for the entire range of the engine loads. These functions were applied to ship activities that were derived from hourly records of Automatic Identification System signals together with a database containing the engine characteristics of the vessels that traveled the North Sea in 2011. The emission model yielded ship emissions among others of NOx and SO2 at high temporal and spatial resolution that were subsequently used in a chemistry transport model in order to simulate the impact of the emissions on pollutant concentration levels. The total emissions of nitrogen reached 540 Gg and those of sulfur oxides 123 Gg within the North Sea - including the adjacent western part of the Baltic Sea until 5° W. This was about twice as much of those of a medium-sized industrialized European state like the Netherlands. The relative contribution of ships to, for example, NO2 concentration levels ashore close to the sea can reach up to 25 % in summer and 15 % in winter. Some hundred kilometers

  9. The impact of shipping emissions on air pollution in the Greater North Sea region - Part 1: Current emissions and concentrations

    NASA Astrophysics Data System (ADS)

    Aulinger, A.; Matthias, V.; Zeretzke, M.; Bieser, J.; Quante, M.; Backes, A.

    2015-04-01

    The North Sea is one of the areas with the highest ship traffic densities worldwide. At any time, about 3000 ships are sailing its waterways. Previous scientific publications have shown that ships contribute significantly to atmospheric concentrations of NOx, particulate matter and ozone. Especially in the case of particulate matter and ozone this influence can even be seen in regions far away from the main shipping routes. In order to quantify the effects of North Sea shipping on air quality in its bordering states, it is essential to determine the emissions from shipping as accurately as possible. Within the Interreg IVb project Clean North Sea Shipping (CNSS) a bottom-up approach was developed and used to thoroughly compile such an emission inventory for 2011 that served as the base year for the current emission situation. The innovative aspect of this approach was to use load dependent functions to calculate emissions from the ships' current activities instead of averaged emission factors for the entire range of the engine loads. These functions were applied to ship activities that were derived from hourly records of Automatic Identification System signals together with a data base containing the engine characteristics of the vessels that traveled the North Sea in 2011. The emission model yielded ship emissions among others of NOx and SO2 in high temporal and spatial resolution that were subsequently used in a chemistry transport model in order to simulate the impact of the emissions on pollutant concentration levels. The total emissions of nitrogen reached 540 Gg and of sulfur oxides 123 Gg within the North Sea, which was about twice as much of those of a medium-sized industrialized European state like the Netherlands. The relative contribution of ships to, for example, NO2 concentration levels ashore close to the sea can reach up to 25% in summer and 15% in winter. Some hundred kilometers away from the sea the contribution was about 6% in summer and 4% in

  10. High-speed Air Temperature Measurements in a Closed-path Cell and Quality of CO2 and H2O Fluxes from a Short-tube Gas Analyzer.

    NASA Astrophysics Data System (ADS)

    Burba, G. G.; Kathilankal, J. C.; Fratini, G.

    2015-12-01

    Gas analyzers traditionally used for eddy covariance method measure gas density. When fluxes are calculated, corrections are applied to account for the changes in gas density due to changing temperature and pressure (Ideal Gas Law) and changing water vapor density (Dalton's Law). The new generation of gas analyzers with fast air temperature and pressure measurements in the sampling cell enables on-the-fly calculation of fast dry mole fraction. This significantly simplifies the flux processing because the WPL density terms are no longer required, and leads to the reduction in uncertainties associated with latent and sensible heat flux inputs into the density terms. Traditional closed-path instruments with long intake tubes often can effectively dampen the fast temperature fluctuations in the tube before reaching the measurement cell, thus reducing or eliminating the need for temperature correction for density-based fluxes. But in instruments with a short-tube design, most - but not all - of the temperature fluctuations are attenuated, so calculating unbiased fluxes using fast dry mole fraction requires high-speed precise temperature measurements of the air stream inside the cell. Fast pressure and water vapor content of the sampled air should also be measured in the cell and carefully aligned in time with gas density and sample temperature measurements.In this study we examine the impact of fast-response air temperature measurements in the cell on the calculations of carbon dioxide and water vapor fluxes at different time scales from three different ecosystems. The fast cell air temperature data is filtered mathematically to obtain slower response cell temperature time series, which is used in the calculation of fluxes. This exercise is intended to simulate the use of thicker slower response thermocouples instead of fast response fine wire thermocouples for estimating cell temperature. The directly measured block temperature is also utilized to illustrate the

  11. Determination of naval medium speed diesel engine air exhaust emissions and validation of a proposed estimation model. Master`s thesis

    SciTech Connect

    Mayeaux, A.M.

    1995-05-01

    Steady state marine diesel engine exhaust emissions are being reviewed by the Environmental Protection Agency for possible regulation. In anticipation of future regulation, the United States Navy is developing appropriate emissions models for naval vessels. A procedure for collecting this data from an U. S. Navy ship with medium speed main propulsion diesels is presented. It is based on similar testing conducted by the U.S. Coast Guard for measuring patrol boat diesel engine emissions and International Standards Organization methodology. The primary challenge of the experiment design was to minimize interference with the engineering plant as the assigned ship was concurrently tasked for other operations. Data gathered allowed calculation of engine rpm, engine load, exhaust gas flow rate, and determination of pollutant amounts. The tests were conducted at a series of predetermined speeds to reflect an 11-Mode duty cycle developed previously for the LSD 41 Class propulsion diesel engines.

  12. Application of an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum.

    PubMed

    Chen, Tao; Liu, Yongling; Zou, Denglang; Chen, Chen; You, Jinmao; Zhou, Guoying; Sun, Jing; Li, Yulin

    2014-01-01

    This study presents an efficient strategy based on liquid-liquid extraction, high-speed counter-current chromatography, and preparative HPLC for the rapid enrichment, separation, and purification of four anthraquinones from Rheum tanguticum. A new solvent system composed of petroleum ether/ethyl acetate/water (4:2:1, v/v/v) was developed for the liquid-liquid extraction of the crude extract from R. tanguticum. As a result, emodin, aloe-emodin, physcion, and chrysophanol were greatly enriched in the organic layer. In addition, an efficient method was successfully established to separate and purify the above anthraquinones by high-speed counter-current chromatography and preparative HPLC. This study supplies a new alternative method for the rapid enrichment, separation, and purification of emodin, aloe-emodin, physcione, and chrysophanol.

  13. Separation of three phenolic high-molecular-weight compounds from the crude extract of Terminalia Chebula Retz. by ultrasound-assisted extraction and high-speed counter-current chromatography.

    PubMed

    Zou, Deng-lang; Chen, Tao; Li, Hong-mei; Chen, Chen; Zhao, Jing-yang; Li, Yu-lin

    2016-04-01

    This study presents an efficient strategy for separation of three phenolic compounds with high molecular weight from the crude extract of Terminalia chebula Retz. by ultrasound-assisted extraction and high-speed counter-current chromatography. The ultrasound-assisted extraction conditions were optimized by response surface methodology and the results showed the target compounds could be well enriched under the optimized extraction conditions. Then the crude extract was directly separated by high-speed counter-current chromatography without any pretreatment using n-hexane/ethyl acetate/methanol/water (1:7:0.5:3, v/v/v/v) as the solvent system. In 180 min, 13 mg of A, 18 mg of B, and 9 mg of C were obtained from 200 mg of crude sample. Their structures were identified as Chebulagic acid (A, 954 Da), Chebulinic acid (B, 956 Da), and Ellagic acid (C) by (1) H NMR spectroscopy. PMID:26864462

  14. Photosynthesis, transpiration and water use efficiencies of a plant canopy and plant leaves under restricted air current conditions

    NASA Astrophysics Data System (ADS)

    Kitaya, Yoshiaki; Shibuya, Toshio; Tsuruyama, Joshin

    A fundamental study was conducted to obtain the knowledge for culturing plants and exchanging gases with plants under restricted air circulation conditions in space agriculture. The effects of air velocities less than 1.3 m s-1 on net photosynthetic rates (Pn), transpiration rates (Tr) and Pn/Tr, water use efficiencies (WUE), of a canopy of cucumber seedlings and of single leaves of cucumber, sweet potato and barley were assessed with assimilation chamber methods in ground based experiments. The cucumber seedling canopy, which had a LAI of 1.4 and height of 0.1 m, was set in a wind tunnel installed in a plant canopy assimilation chamber. Each of the attached single leaves was set in a leaf assimilation chamber. The Pn and Tr of the plant canopy increased to 1.2 and 2.8 times, respectively, and WUE decreased to 0.4 times with increasing the air velocity from 0.02 to 1.3 m s-1. The Pn and Tr of the single leaves of all the species increased by 1.3-1.7 and 1.9-2.2 times, respectively, and WUE decreased to 0.6-0.8 times as the air velocity increased from 0.05 to 0.8 m s-1. The effect of air velocity was more significant on Tr than on Pn and thus WUE decreased with increasing air velocity in both the plant canopy and the individual leaves. The leaf boundary layer resistance was approximately proportional to the minus 1/3 power of the air velocity. Stomatal resistance was almost constant during the experiment. The CO2 concentrations in the sub-stomatal cavity in leaves of cucumber, sweet potato and barley, respectively, were 43, 31 and 58 mmol mol-1 lower at the air velocity of 0.05 m s-1 than at the air velocity of 0.8 m s-1, while the water vapor pressure in the sub-stomatal cavity was constant. We concluded that the change in the CO2 concentration in the sub-stomatal cavity was a cause of the different effect of the air velocity on Pn and Tr, and thus on WUE. The phenomenon will be more remarkable under restricted air convection conditions at lower gravity in space.

  15. Comparison of Predictive Modeling Methods of Aircraft Landing Speed

    NASA Technical Reports Server (NTRS)

    Diallo, Ousmane H.

    2012-01-01

    Expected increases in air traffic demand have stimulated the development of air traffic control tools intended to assist the air traffic controller in accurately and precisely spacing aircraft landing at congested airports. Such tools will require an accurate landing-speed prediction to increase throughput while decreasing necessary controller interventions for avoiding separation violations. There are many practical challenges to developing an accurate landing-speed model that has acceptable prediction errors. This paper discusses the development of a near-term implementation, using readily available information, to estimate/model final approach speed from the top of the descent phase of flight to the landing runway. As a first approach, all variables found to contribute directly to the landing-speed prediction model are used to build a multi-regression technique of the response surface equation (RSE). Data obtained from operations of a major airlines for a passenger transport aircraft type to the Dallas/Fort Worth International Airport are used to predict the landing speed. The approach was promising because it decreased the standard deviation of the landing-speed error prediction by at least 18% from the standard deviation of the baseline error, depending on the gust condition at the airport. However, when the number of variables is reduced to the most likely obtainable at other major airports, the RSE model shows little improvement over the existing methods. Consequently, a neural network that relies on a nonlinear regression technique is utilized as an alternative modeling approach. For the reduced number of variables cases, the standard deviation of the neural network models errors represent over 5% reduction compared to the RSE model errors, and at least 10% reduction over the baseline predicted landing-speed error standard deviation. Overall, the constructed models predict the landing-speed more accurately and precisely than the current state-of-the-art.

  16. Indoor climate and air quality . Review of current and future topics in the field of ISB study group 10

    NASA Astrophysics Data System (ADS)

    Höppe, P.; Martinac, Ivo

    In industrialized countries about 90% of the time is spent indoors. The ambient parameters affecting indoor thermal comfort are air temperature and humidity, air velocity, and radiant heat exchange within an enclosure. In assessing the thermal environment, one needs to consider all ambient parameters, the insulating properties of the occupants' clothing, and the activity level of the occupants by means of heat balance models of the human body. Apart from thermal parameters, air quality (measured and perceived) is also of importance for well-being and health in indoor environments. Pollutant levels are influenced by both outdoor concentrations and by indoor emissions. Indoor levels can thus be lower (e.g. in the case of ozone and SO2) or higher (e.g. for CO2 and formaldehyde) than outdoor levels. Emissions from cooking play an important role, especially in developing countries. The humidity of the ambient air has a wide range of effects on the energy and water balance of the body as well as on elasticity, air quality perception, build-up of electrostatic charge and the formation or mould. However, its effect on the indoor climate is often overestimated. While air-handling systems are commonly used for achieving comfortable indoor climates, their use has also been linked to a variety of problems, some of which have received attention within the context of ''sick building syndrome''.

  17. Indoor climate and air quality. Review of current and future topics in the field of ISB study group 10.

    PubMed

    Höppe, P; Martinac, I

    1998-08-01

    In industrialized countries about 90% of the time is spent indoors. The ambient parameters affecting indoor thermal comfort are air temperature and humidity, air velocity, and radiant heat exchange within an enclosure. In assessing the thermal environment, one needs to consider all ambient parameters, the insulating properties of the occupants' clothing, and the activity level of the occupants by means of heat balance models of the human body. Apart from thermal parameters, air quality (measured and perceived) is also of importance for well-being and health in indoor environments. Pollutant levels are influenced by both outdoor concentrations and by indoor emissions. Indoor levels can thus be lower (e.g. in the case of ozone and SO2) or higher (e.g. for CO2 and formaldehyde) than outdoor levels. Emissions from cooking play an important role, especially in developing countries. The humidity of the ambient air has a wide range of effects on the energy and water balance of the body as well as on elasticity, air quality perception, build-up of electrostatic charge and the formation or mould. However, its effect on the indoor climate is often overestimated. While air-handling systems are commonly used for achieving comfortable indoor climates, their use has also been linked to a variety of problems, some of which have received attention within the context of "sick building syndrome". PMID:9780844

  18. Indoor climate and air quality. Review of current and future topics in the field of ISB study group 10.

    PubMed

    Höppe, P; Martinac, I

    1998-08-01

    In industrialized countries about 90% of the time is spent indoors. The ambient parameters affecting indoor thermal comfort are air temperature and humidity, air velocity, and radiant heat exchange within an enclosure. In assessing the thermal environment, one needs to consider all ambient parameters, the insulating properties of the occupants' clothing, and the activity level of the occupants by means of heat balance models of the human body. Apart from thermal parameters, air quality (measured and perceived) is also of importance for well-being and health in indoor environments. Pollutant levels are influenced by both outdoor concentrations and by indoor emissions. Indoor levels can thus be lower (e.g. in the case of ozone and SO2) or higher (e.g. for CO2 and formaldehyde) than outdoor levels. Emissions from cooking play an important role, especially in developing countries. The humidity of the ambient air has a wide range of effects on the energy and water balance of the body as well as on elasticity, air quality perception, build-up of electrostatic charge and the formation or mould. However, its effect on the indoor climate is often overestimated. While air-handling systems are commonly used for achieving comfortable indoor climates, their use has also been linked to a variety of problems, some of which have received attention within the context of "sick building syndrome".

  19. Ground-Based Experiment of Current Collection to Bare Tether in High-Speed and High-Density Plasma Generated by Hall Thrusters

    SciTech Connect

    Kohori, Tatsuya; Ikeda, Tomoyuki; Shimizu, Masaharu; Takagi, Hiroki; Yamada, Minetsugu; Tahara, Hirokazu

    2008-12-31

    Bare-tether systems are one of the greatest-efficiency electrodynamic tethered systems. The system with an uninsulated portion of the metallic tether itself to collect electrons from the space plasma is operated as a thruster or a power generator on a satellite. Ground-based experiments were carried out to understand phenomena of electron collection by a bare tether in space. Metallic tether samples were exposed to a simulating Low-Earth-Orbit plasma flow as varying tether sample diameter and length, and plasma velocity. A magnetic field was also applied. The normalized collection current increased with normalized tether sample potential. The tether sample diameter did not influence the normalized collection current characteristics although an increase in tether sample length decreased the normalized collection current in this experiment. The collection current characteristics were independent of plasma velocity under meso-thermal conditions. The existence of magnetic field raised the collection current because of the three-dimensional current collection effect at the edge of a tether sample under the magnetic field. Although the existence of magnetic field may raise the collection current, the effect will be small with a long tether. Accordingly, the dependence of tether diameter and length, plasma velocity and magnetic field on collection current characteristics of a bare tether in space might be small. The collection current may not exceed the OML current.

  20. Method and device for optimizing the air-fuel mixture burn rate of internal combustion engines during low speed, light and heavy load operating conditions

    SciTech Connect

    Burandt, C.O.

    1990-10-09

    This patent describes a method for optimizing low speed light load and low speed heavy load operating conditions in an internal combustion engine. The engine has a camshaft, a crankshaft, at least one intake valve and at least one piston, and is capable of providing for small valve events, and the engine providing for earlier than normal intake valve closings the method comprises: sensing the load demand on the engine, regulating the phasing of the operation of the camshaft of the engine with the operation of the crankshaft of the engine in response to the sensed load demand by advancing the operation of camshaft relative to the operation of the crankshaft when a heavy load demand is sensed and by retarding the operation of the camshaft relative to the operation of the crankshaft when alight load demand is sensed, and sensing detonation in the engine and regulating the phasing operation of the camshaft relative to the operation of the crankshaft by advancing the operation of the camshaft relative to the crankshaft when detonation is sensed.

  1. Pulse Detonation Engines for High Speed Flight

    NASA Technical Reports Server (NTRS)

    Povinelli, Louis A.

    2002-01-01

    Revolutionary concepts in propulsion are required in order to achieve high-speed cruise capability in the atmosphere and for low cost reliable systems for earth to orbit missions. One of the advanced concepts under study is the air-breathing pulse detonation engine. Additional work remains in order to establish the role and performance of a PDE in flight applications, either as a stand-alone device or as part of a combined cycle system. In this paper, we shall offer a few remarks on some of these remaining issues, i.e., combined cycle systems, nozzles and exhaust systems and thrust per unit frontal area limitations. Currently, an intensive experimental and numerical effort is underway in order to quantify the propulsion performance characteristics of this device. In this paper, we shall highlight our recent efforts to elucidate the propulsion potential of pulse detonation engines and their possible application to high-speed or hypersonic systems.

  2. The effects of engine speed and injection characteristics on the flow field and fuel/air mixing in motored two-stroke diesel engines

    NASA Technical Reports Server (NTRS)

    Nguyen, H. L.; Carpenter, M. H.; Ramos, J. I.

    1987-01-01

    A numerical analysis is presented on the effects of the engine speed, injection angle, droplet distribution function, and spray cone angle on the flow field, spray penetration and vaporization, and turbulence in a turbocharged motored two-stroke diesel engine. The results indicate that the spray penetration and vaporization, velocity, and turbulence kinetic energy increase with the intake swirl angle. Good spray penetration, vaporization, and mixing can be achieved by injecting droplets of diameters between 50 and 100 microns along a 120-deg cone at about 315 deg before top-dead-center for an intake swirl angle of 30 deg. The spray penetration and vaporization were found to be insensitive to the turbulence levels within the cylinder. The results have also indicated that squish is necessary in order to increase the fuel vaporization rate and mixing.

  3. Direct measurement of the characteristic three-body electron attachment time in the atmospheric air in direct current electric field

    SciTech Connect

    Shutov, A. V.; Smetanin, I. V.; Ionin, A. A.; Levchenko, A. O.; Seleznev, L. V.; Sinitsyn, D. V.; Ustinovskii, N. N.; Zvorykin, V. D.

    2013-07-15

    We report the results of theoretical and experimental study of the characteristic time for three-body attachment of electrons produced by 100 fs UV laser pulse in the atmosphere air in the external DC electric field ranged from 0.2 to 10 kV/cm.

  4. 77 FR 11145 - Intent to Request Renewal From OMB of One Current Public Collection of Information: Air Cargo...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-24

    ... number 1652-0053. While aviation security requirements have greatly reduced the vulnerability of the air..., and compliance. The forms used in this collection of information include the Aviation Security Known... KSMS or IACMS, the regulated entity must conduct a physical visit of the shipper using the...

  5. Exposure Information in Environmental Health Research: Current Opportunities and Future Directions for Particulate Matter, Ozone, and Toxic Air Pollutants

    EPA Science Inventory

    In September 2006, scientists from the US Environmental Protection Agency (EPA) and the Centers for Disease Control and Prevention (CDC) along with scientists from the academic community and state health departments convened a symposium on air pollution exposure and health in ord...

  6. Current research in NRMRL on the mitigation of near-road air pollution by vegetative and structural barriers

    EPA Science Inventory

    Numerous research studies published in scientific literature have shown that people living, working, and going to school near large roads experience increased adverse health effects. In addition, studies show that air pollution is worse in close proximity to major roadways (e.g....

  7. Molecular optical air data system (MOADS)

    NASA Astrophysics Data System (ADS)

    Tchoryk, Peter, Jr.; Watkins, Christopher B.; Lindemann, Scott K.; Hays, Paul B.; Nardell, Carl A.

    2001-09-01

    The Molecular Optical Air Data System (MOADS) is a compact optical instrument that can directly measure wind speed and direction, density, and temperature of the air surrounding an aircraft. From these measurements, a complete set of air data products can be determined. Single-axis wind tunnel testing of wind speed and density has just been completed for the current prototype. These wind tunnel measurements have shown that the current prototype meets wind speed accuracy predictions and initial results from density testing indicate a high level of correlation with absolute pressure transducer measurements. A preliminary design for the next generation instrument, the Joint Optical Air Data System (JOADS), has been completed and is intended to meet Joint Striker Fighter (JSF) requirements. Work is also underway to evaluate the application of MOADS to Unmanned Air Vehicles (UAVs), Reusable Launch Vehicles (RLVs), helicopters and weapon systems. Extensions of MOADS technology to wind shear, gust alleviation, and clear air turbulence detection for commercial aircraft are also being pursued. The basic instrument operation, preliminary ground testing (wind tunnel) results, comparison of these results to simulations, next generation instrument capabilities, and plans for a flight demonstration are discussed.

  8. Impact of aviation emissions on UTLS and air quality in current and future climate - GEM-AC model simulations

    NASA Astrophysics Data System (ADS)

    Kaminski, J. W.

    2015-12-01

    The objective of this study is to investigate the potential impacts of aviation emissions on the upper troposphere and lower stratosphere (UTLS) and surface air quality. The tool that was used in our study is the GEM-AC (Global Environmental Multiscale with Atmospheric Chemistry) chemical weather model where air quality, free tropospheric and stratospheric chemistry processes are on-line and interactive in a weather forecast model of Environment Canada. In vertical, the model domain is defined on 70 hybrid levels from the surface to ~60km. The gas-phase chemistry includes a comprehensive set of reactions for Ox, NOx, HOx, CO, CH4, NMVOCs, halocarbons, ClOx and BrO. Also, the model can address aerosol microphysics and gas-aerosol partitioning. Aircraft emissions are provided by the AEDT 2006 database developed by the Federal Aviation Administration. Results from model simulations on a global variable grid with 1 degree uniform resolution in the northern hemisphere will be presented.

  9. Implementation of Temperature Sequential Controller on Variable Speed Drive

    NASA Astrophysics Data System (ADS)

    Cheong, Z. X.; Barsoum, N. N.

    2008-10-01

    There are many pump and motor installations with quite extensive speed variation, such as Sago conveyor, heating, ventilation and air conditioning (HVAC) and water pumping system. A common solution for these applications is to run several fixed speed motors in parallel, with flow control accomplish by turning the motors on and off. This type of control method causes high in-rush current, and adds a risk of damage caused by pressure transients. This paper explains the design and implementation of a temperature speed control system for use in industrial and commercial sectors. Advanced temperature speed control can be achieved by using ABB ACS800 variable speed drive-direct torque sequential control macro, programmable logic controller and temperature transmitter. The principle of direct torque sequential control macro (DTC-SC) is based on the control of torque and flux utilizing the stator flux field orientation over seven preset constant speed. As a result of continuous comparison of ambient temperature to the references temperatures; electromagnetic torque response is particularly fast to the motor state and it is able maintain constant speeds. Experimental tests have been carried out by using ABB ACS800-U1-0003-2, to validate the effectiveness and dynamic respond of ABB ACS800 against temperature variation, loads, and mechanical shocks.

  10. Tannase-mediated biotransformation assisted separation and purification of theaflavin and epigallocatechin by high speed counter current chromatography and preparative high performance liquid chromatography: A comparative study.

    PubMed

    Xia, Guobin; Lin, Chunfang; Liu, Songbai

    2016-09-01

    A large scale isolation and purification of theaflavin (TF) and epigallocatechin (EGC) has been successfully developed by tannase-mediated biotransformation combining high-speed countercurrent chromatography. After tannase hydrolysis of a commercially available theaflavins extract (TE), the content of TF and EGC in tannase-mediated biotransformation product (TBP) achieved approximately 3 times enrichment. SEM studies revealed smooth tannase biotransformation and the possibility of recovery of the tannase. A single 1.5 hours' HSCCC separation for TF and EGC employing a two-phase solvent system could simultaneously produce 180.8 mg of 97.3% purity TF and 87.5 mg of 97.3% purity EGC. However, a preparative HPLC separation of maximum injection volume containing 120 mg TBP prepared 11.2 mg TF of 94.9% purity and 7.7 mg EGC of 89.9% purity. HSCCC separation demonstrated significant advantages over Prep HPLC in terms of sample loading size, separation time, environmental friendly solvent systems, and the production. PMID:27389804

  11. Analysis and determination of oestrogen-active compounds in fructus amomi by the combination of high-speed counter-current chromatography and high performance liquid chromatography.

    PubMed

    Ying, Hao; Liu, Jinpeng; Du, Qizhen

    2014-05-01

    Amomum longiligulare or Amomum villosum showed oestrogenic activity. In the present study, oestrogen-active components in fructus amomi, the seeds of A. longiligulare were separated by high-speed countercurrent chromatography (HSCCC) using stepwise elution of eight mobile phases with gradient polarity and advanced separation by high performance liquid chromatography (HPLC). The results yielded 17 compounds with the amount of 8-138mg and a purity of 94.3-99.8% from a 3g ethanolic extract of fructus amomi. The chemical structures of the compounds were identified by ESI-MS and NMR spectra, in which eight diarylheptanoids were demonstrated as the main oestrogen-active compounds in the fructus amomi. Determination of the diarylheptanoids in fructus amomi from various origins showed that fructus amomi contains more than 0.5% total diarylheptanoids. The results showed that fructus amomi is a diarylheptanoids-rich food resource possessing oestrogen-activity. The combination method of HSCCC and HPLC can be applied for the analysis of bioactive compounds by detecting the corresponding bioactivity in the HSCCC fractions and separating the target compounds with HPLC.

  12. Tannase-mediated biotransformation assisted separation and purification of theaflavin and epigallocatechin by high speed counter current chromatography and preparative high performance liquid chromatography: A comparative study.

    PubMed

    Xia, Guobin; Lin, Chunfang; Liu, Songbai

    2016-09-01

    A large scale isolation and purification of theaflavin (TF) and epigallocatechin (EGC) has been successfully developed by tannase-mediated biotransformation combining high-speed countercurrent chromatography. After tannase hydrolysis of a commercially available theaflavins extract (TE), the content of TF and EGC in tannase-mediated biotransformation product (TBP) achieved approximately 3 times enrichment. SEM studies revealed smooth tannase biotransformation and the possibility of recovery of the tannase. A single 1.5 hours' HSCCC separation for TF and EGC employing a two-phase solvent system could simultaneously produce 180.8 mg of 97.3% purity TF and 87.5 mg of 97.3% purity EGC. However, a preparative HPLC separation of maximum injection volume containing 120 mg TBP prepared 11.2 mg TF of 94.9% purity and 7.7 mg EGC of 89.9% purity. HSCCC separation demonstrated significant advantages over Prep HPLC in terms of sample loading size, separation time, environmental friendly solvent systems, and the production.

  13. Rapid doubling of the critical current of Yba{sub 2}Cu{sub 3}O{sub 7-{delta}} coated conductor for viable high-speed industrial processing.

    SciTech Connect

    Leroux, M.; Kihlstrom, K. J.; Holleis, S.; Rupich, M. W.; Sathyamurthy, S.; Fleshler, S.; Sheng, H. P.; Miller, D. J.; Eley, S.; Civale, L.; Kayani, A.; Niraula, P. M.; Welp, U.; Kwok, W. -K.

    2015-11-09

    We demonstrate that 3.5-MeV oxygen irradiation can markedly enhance the in-field critical current of commercial 2nd generation superconducting tapes with an exposure time of just one second per 0.8 cm2. The speed demonstrated here is now at the level required for an industrial reel-to-reel post-processing. The irradiation is made on production line samples through the protective silver coating and does not require any modification of the growth process. From TEM imaging, we identify small clusters as the main source of increased vortex pinning.

  14. Rapid doubling of the critical current of YBa{sub 2}Cu{sub 3}O{sub 7−δ} coated conductors for viable high-speed industrial processing

    SciTech Connect

    Leroux, M.; Welp, U.; Kwok, W.-K.; Kihlstrom, K. J.; Holleis, S.; Rupich, M. W.; Sathyamurthy, S.; Fleshler, S.; Sheng, H. P.; Miller, D. J.; Eley, S.; Civale, L.; Kayani, A.; Niraula, P. M.

    2015-11-09

    We demonstrate that 3.5-MeV oxygen irradiation can markedly enhance the in-field critical current of commercial second generation superconducting tapes with an exposure time of just 1 s per 0.8 cm{sup 2}. The speed demonstrated here is now at the level required for an industrial reel-to-reel post-processing. The irradiation is made on production line samples through the protective silver coating and does not require any modification of the growth process. From TEM imaging, we identify small clusters as the main source of increased vortex pinning.

  15. Injection, atomization, ignition and combustion of liquid fuels in high-speed air streams. Annual scientific report 1 December 81-31 December 82

    SciTech Connect

    Schetz, J.A.

    1983-01-01

    A simulation approach to studying hot flow subsonic cross-stream fuel injection problems in a less complex and costly cold flow facility was developed. A typical ramjet combustion chamber fuel injection problem was posed where ambient temperature fuel (Kerosene) is injected into a hot airstream. This case was transformed through two new similarity parameters involving injection and freestream properties to a simulated case where a chilled injectant is injected into an ambient temperature airstream. Experiments for the simulated case using chilled Freon-12 injected into the Va. Tech 23 x 23 cm. blow-down wind tunnel at a freestream Mach number of 0.44 were run. The freestream stagnation pressure and temperature were held at 2.5 atm. and 300 degrees K respectively. Results showed a clear picture of the mechanisms of jet decomposition in the presence of rapid vaporization. Immediately after injection a vapor cloud was formed in the jet plume, which dissipated downstream leaving droplets on the order of 8 to 10 microns in diameter for the conditions examined. This represents a substantial reduction compared to baseline tests run at the same conditions with water which had little vaporization. The desirability of using slurry fuels for aerospace application has long been recognized, but the problems of slurry combustion have delayed their use. The present work is an experimental and numerical investigation into the break-up and droplet formation of laminar slurry jets issuing into quiescent air.

  16. Direct AFM force measurements between air bubbles in aqueous polydisperse sodium poly(styrene sulfonate) solutions: effect of collision speed, polyelectrolyte concentration and molar mass.

    PubMed

    Browne, Christine; Tabor, Rico F; Grieser, Franz; Dagastine, Raymond R

    2015-07-01

    Interactions between colliding air bubbles in aqueous solutions of polydisperse sodium poly(styrene sulfonate) (NaPSS) using direct force measurements were studied. The forces measured with deformable interfaces were shown to be more sensitive to the presence of the polyelectrolytes when compared to similar measurements using rigid interfaces. The experimental factors that were examined were NaPSS concentration, bubble collision velocity and polyelectrolyte molar mass. These measurements were then compared with an analytical model based on polyelectrolyte scaling theory in order to explain the effects of concentration and bubble deformation on the interaction between bubbles. Typically structural forces from the presence of monodisperse polyelectrolyte between interacting surfaces may be expected, however, it was found that the polydispersity in molar mass resulted in the structural forces to be smoothed and only a depletion interaction was able to be measured between interacting bubbles. It was found that an increase in number density of NaPSS molecules resulted in an increase in the magnitude of the depletion interaction. Conversely this interaction was overwhelmed by an increase in the fluid flow in the system at higher bubble collision velocities. Polymer molar mass dispersity plays a significant role in the interactions present between the bubbles and has implications that also affect the polyelectrolyte overlap concentration of the solution. Further understanding of these implications can be expected to play a role in the improvement in operations in such fields as water treatment and mineral processing where polyelectrolytes are used extensively.

  17. The Arteries of Global Trade: Industrial Restructuring and Technological Change in the Transatlantic Air Cargo Industry

    ERIC Educational Resources Information Center

    Schwarz, Guido

    2010-01-01

    Air cargo enjoys a special importance: together with maritime transport it is the backbone of global trade and is indispensable for contemporary globalization. Air transport is the only mode that combines worldwide reach with high speed. Nonetheless there is a dearth of geographic research that analyzes the current restructuring affecting the air…

  18. Design Optimization and the Limits of Steady-State Heating Efficiency for Conventional Single-Speed Air-Source Heat Pumps

    SciTech Connect

    Rice, C.K.

    2001-06-06

    The ORNL Heat Pump Model and an optimizing program were used to explore the limits of steady-state heating efficiency for conventional air-source heat pumps. The method used allows for the simultaneous optimization of ten selected design variables, taking proper account of their interactions, while constraining other parameters to chosen limits or fixed values. Designs were optimized for a fixed heating capacity, but the results may be scaled to other capacities. Substantial performance improvement is predicted compared to today's state of the art heat pump. With increased component efficiencies that are expected in the near future and with modest increases in heat exchanger area, a 28% increase in heating efficiency is predicted; for long-term improvements with considerably larger heat exchangers, a 56% increase is possible. The improved efficiencies are accompanied by substantial reductions in the requirements for compressor and motor size. The predicted performance improvements are attributed not only to improved components and larger heat exchangers but also to the use of an optimizing design procedure. Deviations from the optimized design may be necessary to make use of available component sizes and to maintain good cooling-mode performance while improving the heating efficiency. Sensitivity plots (i.e., COP as a function of one or more design parameters) were developed to explore design flexibilities and to evaluate their consequences. The performance of the optimized designs was compared to that of modified ideal cycles to assess the factors that limit further improvement. It is hoped that the design methods developed will be useful to designers in the heat pump industry.

  19. High-Speed Schlieren Movies of Decelerators at Supersonic Speeds

    NASA Technical Reports Server (NTRS)

    1960-01-01

    High-Speed Schlieren Movies of Decelerators at Supersonic Speeds. Tests were conducted on several types of porous parachutes, a paraglider, and a simulated retrorocket. Mach numbers ranged from 1.8-3.0, porosity from 20-80 percent, and camera speeds from 1680-3000 feet per second (fps) in trials with porous parachutes. Trials of reefed parachutes were conducted at Mach number 2.0 and reefing of 12-33 percent at camera speeds of 600 fps. A flexible parachute with an inflatable ring in the periphery of the canopy was tested at Reynolds number 750,000 per foot, Mach number 2.85, porosity of 28 percent, and camera speed of 36oo fps. A vortex-ring parachute was tested at Mach number 2.2 and camera speed of 3000 fps. The paraglider, with a sweepback of 45 degrees at an angle of attack of 45 degrees was tested at Mach number 2.65, drag coefficient of 0.200, and lift coefficient of 0.278 at a camera speed of 600 fps. A cold air jet exhausting upstream from the center of a bluff body was used to simulate a retrorocket. The free-stream Mach number was 2.0, free-stream dynamic pressure was 620 lb/sq ft, jet-exit static pressure ratio was 10.9, and camera speed was 600 fps. [Entire movie available on DVD from CASI as Doc ID 20070030973. Contact help@sti.nasa.gov

  20. Fishing and knockout of bioactive compounds using a combination of high-speed counter-current chromatography (HSCCC) and preparative HPLC for evaluating the holistic efficacy and interaction of the components of Herba Epimedii.

    PubMed

    Jin, Jing; Li, Yubo; Kipletting Tanui, Emmanuel; Han, Liwen; Jia, Yuan; Zhang, Lu; Wang, Yuming; Zhang, Xiuxiu; Zhang, Yanjun

    2013-05-20

    Due to the complex chemical compositions and pharmacological effects of traditional Chinese medicines, we developed a strategy based on fishing and knockout of bioactive compounds using a combination of high-speed counter-current chromatography (HSCCC) and preparative HPLC for evaluating the holistic activity and interaction of the components of Herba Epimedii. First, osteoblast target cell extraction was used for preliminary screening of the potential bioactive compounds of Herba Epimedii. Second, the bioactive compounds identified (epimedin A, epimedin B, epimedin C and icariin) were fished and knocked out using high-speed counter-current chromatography and preparative HPLC. Third, the bioactivity of resulting fractions was assessed by determining their influence on cell proliferation and differentiation, thereby allowing for an evaluation of their interaction.The pharmacodynamic contribution ratio of each bioactive compound to the efficacy of the herbal medicine could then be comprehensively and intuitively determined based on the spectra-activity correlations (VIP values) of the tested compositions using partial least-squares regression (PLS-R), through which the reliability of the screening and isolation of bioactive compounds by the target cell extraction technique were verified. The proposed strategy is a useful approach with potential application in other traditional Chinese medicines.

  1. Development of a numerical model for the electric current in burner-stabilised methane-air flames

    NASA Astrophysics Data System (ADS)

    Speelman, N.; de Goey, L. P. H.; van Oijen, J. A.

    2015-03-01

    This study presents a new model to simulate the electric behaviour of one-dimensional ionised flames and to predict the electric currents in these flames. The model utilises Poisson's equation to compute the electric potential. A multi-component diffusion model, including the influence of an electric field, is used to model the diffusion of neutral and charged species. The model is incorporated into the existing CHEM1D flame simulation software. A comparison between the computed electric currents and experimental values from the literature shows good qualitative agreement for the voltage-current characteristic. Physical phenomena, such as saturation and the diodic effect, are captured by the model. The dependence of the saturation current on the equivalence ratio is also captured well for equivalence ratios between 0.6 and 1.2. Simulations show a clear relation between the saturation current and the total number of charged particles created. The model shows that the potential at which the electric field saturates is strongly dependent on the recombination rate and the diffusivity of the charged particles. The onset of saturation occurs because most created charged particles are withdrawn from the flame and because the electric field effects start dominating over mass based diffusion. It is shown that this knowledge can be used to optimise ionisation chemistry mechanisms. It is shown numerically that the so-called diodic effect is caused primarily by the distance the heavier cations have to travel to the cathode.

  2. Time domain algorithm for accelerated determination of the first order moment of photo current fluctuations in high speed laser Doppler perfusion imaging.

    PubMed

    Draijer, Matthijs; Hondebrink, Erwin; van Leeuwen, Ton; Steenbergen, Wiendelt

    2009-10-01

    Advances in optical array sensor technology allow for the real time acquisition of dynamic laser speckle patterns generated by tissue perfusion, which, in principle,allows for real time laser Doppler perfusion imaging(LDPI). Exploitation of these developments is enhanced with the introduction of faster algorithms to transform photo currents into perfusion estimates using the first moment of the power spectrum. A time domain (TD)algorithm is presented for determining the first-order spectral moment. Experiments are performed to compare this algorithm with the widely used Fast Fourier Transform(FFT). This study shows that the TD-algorithm is twice as fast as the FFT-algorithm without loss of accuracy.Compared to FFT, the TD-algorithm is efficient in terms of processor time, memory usage and data transport. PMID:19820976

  3. PMSM sensorless control with separate control strategies and smooth switch from low speed to high speed.

    PubMed

    Chen, SiYi; Luo, Ying; Pi, YouGuo

    2015-09-01

    This paper proposes a smooth switching scheme with separate control strategies on low speed mode and high speed mode for permanent magnet synchronous motor (PMSM) sensorless control to improve the overall performance in full speed range. Constant voltage/frequency tuning method is used on low speed mode because the rotor position can hardly be estimated precisely at low speed. Along with the increasing speed, the control strategy can be switched to high speed mode smoothly when current and speed meet the given requirements. In this high speed mode, the current tracking with a sliding mode observer (SMO) and speed tracking with a sliding mode controller (SMC) are handled, respectively. Experimental demonstration is presented to show the desired performance in full speed range of the PMSM sensorless control using the proposed control scheme in this paper.

  4. Improved high-speed counter-current chromatograph with three multilayer coils connected in series. I. Design of the apparatus and performance of semipreparative columns in 2,4-dinitrophenyl amino acid separation.

    PubMed

    Ito, Y; Oka, H; Slemp, J L

    1989-07-28

    A compact desktop model of a high-speed counter-current chromatograph holds three identical multilayer coils in the symmetrical positions around the rotary frame to maintain perfect balance of the centrifuge system without the use of a counterweight. These multilayer coils are connected in series to make up a total capacity of 400 ml while the unique gear arrangement on the rotary frame establishes a twist-free mechanism of the flow tubes so that continuous elution can be performed without the use of rotary seal. The high performance of the present system was successfully demonstrated in separations of 10-250 mg of 2,4-dinitrophenyl amino acid mixtures in a two-phase solvent system composed of chloroform-acetic acid-0.1 M hydrochloric acid (2:2:1, v/v/v). PMID:2777957

  5. AMBIENT AIR MONITORING STRATEGY

    EPA Science Inventory

    The Clean Air Act requires EPA to establish national ambient air quality standards and to regulate as necessary, hazardous air pollutants. EPA uses ambient air monitoring to determine current air quality conditions, and to assess progress toward meeting these standards and relat...

  6. Systems and methods for vehicle speed management

    DOEpatents

    Sujan, Vivek Anand; Vajapeyazula, Phani; Follen, Kenneth; Wu, An; Forst, Howard Robert

    2016-03-01

    Controlling a speed of a vehicle based on at least a portion of a route grade and a route distance divided into a plurality of route sections, each including at least one of a section grade and section length. Controlling the speed of the vehicle is further based on determining a cruise control speed mode for the vehicle for each of the plurality of route sections and determining a speed reference command of the vehicle based on at least one of the cruise control speed mode, the section length, the section grade, and a current speed.

  7. High-Speed Schlieren Movies of Decelerators at Supersonic Speeds

    NASA Technical Reports Server (NTRS)

    1960-01-01

    Tests were conducted on several types of porous parachutes, a paraglider, and a simulated retrorocket. Mach numbers ranged from 1.8-3.0, porosity from 20-80 percent, and camera speeds from 1680-3000 feet per second (fps) in trials with porous parachutes. Trials of reefed parachutes were conducted at Mach number 2.0 and reefing of 12-33 percent at camera speeds of 600 fps. A flexible parachute with an inflatable ring in the periphery of the canopy was tested at Reynolds number 750,000 per foot, Mach number 2.85, porosity of 28 percent, and camera speed of 36oo fps. A vortex-ring parachute was tested at Mach number 2.2 and camera speed of 3000 fps. The paraglider, with a sweepback of 45 degrees at an angle of attack of 45 degrees was tested at Mach number 2.65, drag coefficient of 0.200, and lift coefficient of 0.278 at a camera speed of 600 fps. A cold air jet exhausting upstream from the center of a bluff body was used to simulate a retrorocket. The free-stream Mach number was 2.0, free-stream dynamic pressure was 620 lb/sq ft, jet-exit static pressure ratio was 10.9, and camera speed was 600 fps.

  8. Aeronautic Instruments. Section III : Aircraft Speed Instruments

    NASA Technical Reports Server (NTRS)

    Hunt, Franklin L; Stearns, H O

    1923-01-01

    Part 1 contains a discussion and description of the various types of air speed measuring instruments. The authors then give general specifications and performance requirements with the results of tests on air speed indicators at the Bureau of Standards. Part 2 reports methods and laboratory apparatus used at the Bureau of Standards to make static tests. Methods are also given of combining wind tunnel tests with static tests. Consideration is also given to free flight tests. Part 3 discusses the problem of finding suitable methods for the purpose of measuring the speed of aircraft relative to the ground.

  9. Study of the effects of environmental parameters on the gas/particle partitioning of current-use pesticides in urban air

    NASA Astrophysics Data System (ADS)

    Sauret, Nathalie; Wortham, Henri; Putaud, Jean-Philippe; Mirabel, Philippe

    A filter-XAD-2 resin plug high-volume air sampler was used to collect particulate (P) and gaseous (G) phases of seven pesticides (atrazine, terbuthylazine, alachlor, metolachlor, cymoxanil, diflufenicanil, and fenoxaprop- p-ethyl) and two metabolites (de-ethylatrazine (DEA) and de-ethylterbuthylazine (DET)) in downtown Strasbourg (France). Most of the molecules listed above were found to be associated only with particulate aerosols and only four of them were detected regularly in both atmospheric phases (particulate and gaseous). The results presented in this work showed that models developed previously to describe the gas/particle (G/P) partitioning did not work for currently used pesticides. A new partition equation ( Korg, m 3 ng -1) was defined for the pesticides under study using environmental parameters such as temperature, relative humidity, and organic carbon content of atmospheric aerosols.

  10. Superplane! High Speed Civil Transport

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The High Speed Civil Transport (HSCT). This light-hearted promotional piece explains what the HSCT 'Superplane' is and what advantages it will have over current aircraft. As envisioned, the HSCT is a next-generation supersonic (faster than the speed of sound) passenger jet that would fly 300 passengers at more than 1,500 miles per hour -- more than twice the speed of sound. It will cross the Pacific or Atlantic in less than half the time of modern subsonic jets, and at a ticket price less than 20 percent above comparable, slower flights

  11. ISOTHERMAL AIR INGRESS VALIDATION EXPERIMENTS

    SciTech Connect

    Chang H Oh; Eung S Kim

    2011-09-01

    Idaho National Laboratory carried out air ingress experiments as part of validating computational fluid dynamics (CFD) calculations. An isothermal test loop was designed and set to understand the stratified-flow phenomenon, which is important as the initial air flow into the lower plenum of the very high temperature gas cooled reactor (VHTR) when a large break loss-of-coolant accident occurs. The unique flow characteristics were focused on the VHTR air-ingress accident, in particular, the flow visualization of the stratified flow in the inlet pipe to the vessel lower plenum of the General Atomic’s Gas Turbine-Modular Helium Reactor (GT-MHR). Brine and sucrose were used as heavy fluids, and water was used to represent a light fluid, which mimics a counter current flow due to the density difference between the stimulant fluids. The density ratios were changed between 0.87 and 0.98. This experiment clearly showed that a stratified flow between simulant fluids was established even for very small density differences. The CFD calculations were compared with experimental data. A grid sensitivity study on CFD models was also performed using the Richardson extrapolation and the grid convergence index method for the numerical accuracy of CFD calculations . As a result, the calculated current speed showed very good agreement with the experimental data, indicating that the current CFD methods are suitable for predicting density gradient stratified flow phenomena in the air-ingress accident.

  12. Speed-Dependent Broadening and Line-Mixing in CH_4 Perturbed by Air Near 1.64 μm for the French/german Climate Mission MERLIN

    NASA Astrophysics Data System (ADS)

    Delahaye, Thibault; Tran, Thi Ngoc Ha; Reed, Zachary; Maxwell, Stephen E.; Hodges, Joseph

    2015-06-01

    Climate change is one of the greatest challenges presently facing mankind, and methane is one of the most powerful anthropogenic greenhouse gases. For a better understanding of future climate trends, a satellite dedicated to the measurements of atmospheric methane is under joint development by the French and German space research centers (CNES and DLR). The so-called MERLIN mission (Methane Remote Sensing Lidar Mission, 2019) aims at providing global information on atmospheric methane concentration with a relative uncertainty less than 2% and with a spatial resolution of 50 km Such spectroscopic monitoring of gases in the atmosphere of the Earth, requires a precise description of absorption lines shapes that goes beyond the usual Voigt profile (VP). In the case of methane, the differences between the measured profiles and those given by the VP can be very important, making the VP completely incompatible with the reliable detection of sources and sinks from space. In this work, we present the first results on the modeling of methane lines broadened by air in the 1.64 μm region and the associated spectroscopic parameters, taking into account various collisional effects between molecules that are neglected by the VP: collisional interference between the lines (line-mixing), collision-induced velocity changes (Dicke narrowing effect) and speed dependence of the collisional broadening and shifting. These results were obtained by simultaneously fitting the model parameters to high sensitivity and high-resolution cavity ring-down spectroscopy (CRDS) spectra recorded at the National Institute of Standards and Technology (NIST) over a wide pressure range (5 to 100 kPa). These spectroscopic data and the associated model to calculate the spectrum absorption coefficient will be then used to analyze ground-based atmospheric spectra at the TCCON facility in Park Falls, Wisconsin. C. Kiemle, M. Quatrevalet, G. Ehret et al., Atmos. Meas. Tech. 4 (2011) H. Tran, J.-M. Hartmann, G

  13. The need for speed

    PubMed Central

    Suhalim, Jeffrey L.; Boik, John C.; Tromberg, Bruce J.; Potma, Eric O.

    2012-01-01

    One of the key enabling features of coherent Raman scattering (CRS) techniques is the dramatically improved imaging speed over conventional vibrational imaging methods. It is this enhanced imaging acquisition rate that has guided the field of vibrational microscopy into the territory of real-time imaging of live tissues. In this feature article, we review several aspects of fast vibrational imaging and discuss new applications made possible by the improved CRS imaging capabilities. In addition, we reflect on the current limitations of CRS microscopy and look ahead at several new developments towards real-time, hyperspectral vibrational imaging of biological tissues. PMID:22344721

  14. Experiments on high speed ejectors

    NASA Technical Reports Server (NTRS)

    Wu, J. J.

    1986-01-01

    Experimental studies were conducted to investigate the flow and the performance of thrust augmenting ejectors for flight Mach numbers in the range of 0.5 to 0.8, primary air stagnation pressures up to 107 psig (738 kPa), and primary air stagnation temperatures up to 1250 F (677 C). The experiment verified the existence of the second solution ejector flow, where the flow after complete mixing is supersonic. Thrust augmentation in excess of 1.2 was demonstrated for both hot and cold primary jets. The experimental ejector performed better than the corresponding theoretical optimal first solution ejector, where the mixed flow is subsonic. Further studies are required to realize the full potential of the second solution ejector. The research program was started by the Flight Dynamics Research Corporation (FDRC) to investigate the characteristic of a high speed ejector which augments thrust of a jet at high flight speeds.

  15. Metal-Air Batteries

    SciTech Connect

    Zhang, Jiguang; Bruce, Peter G.; Zhang, Gregory

    2011-08-01

    Metal-air batteries have much higher specific energies than most currently available primary and rechargeable batteries. Recent advances in electrode materials and electrolytes, as well as new designs on metal-air batteries, have attracted intensive effort in recent years, especially in the development of lithium-air batteries. The general principle in metal-air batteries will be reviewed in this chapter. The materials, preparation methods, and performances of metal-air batteries will be discussed. Two main metal-air batteries, Zn-air and Li-air batteries will be discussed in detail. Other type of metal-air batteries will also be described.

  16. Reactive uptake coefficients for N2O5 determined from aircraft measurements during the Second Texas Air Quality Study: Comparison to current model parameterizations

    NASA Astrophysics Data System (ADS)

    Brown, Steven S.; Dubé, William P.; Fuchs, Hendrik; Ryerson, Thomas B.; Wollny, Adam G.; Brock, Charles A.; Bahreini, Roya; Middlebrook, Ann M.; Neuman, J. Andrew; Atlas, Elliot; Roberts, James M.; Osthoff, Hans D.; Trainer, Michael; Fehsenfeld, Frederick C.; Ravishankara, A. R.

    2009-04-01

    This paper presents determinations of reactive uptake coefficients for N2O5, γ(N2O5), on aerosols from nighttime aircraft measurements of ozone, nitrogen oxides, and aerosol surface area on the NOAA P-3 during Second Texas Air Quality Study (TexAQS II). Determinations based on both the steady state approximation for NO3 and N2O5 and a plume modeling approach yielded γ(N2O5) substantially smaller than current parameterizations used for atmospheric modeling and generally in the range 0.5-6 × 10-3. Dependence of γ(N2O5) on variables such as relative humidity and aerosol composition was not apparent in the determinations, although there was considerable scatter in the data. Determinations were also inconsistent with current parameterizations of the rate coefficient for homogenous hydrolysis of N2O5 by water vapor, which may be as much as a factor of 10 too large. Nocturnal halogen activation via conversion of N2O5 to ClNO2 on chloride aerosol was not determinable from these data, although limits based on laboratory parameterizations and maximum nonrefractory aerosol chloride content showed that this chemistry could have been comparable to direct production of HNO3 in some cases.

  17. Engine with speed responsive multi-ratio turbocharger drive

    SciTech Connect

    McCreary, Ch.H.

    1984-05-01

    An internal combustion engine, especially of the two stroke cycle diesel type, has a turbocharger with a supplemental mechanical drive for maintaining a minimum speed ratio relative to engine speed, when exhaust energy is insufficient to provide a higher speed, so as to maintain adequate charging air for engine operation throughout the engine speed range. In order to provide more efficient operation during engine operation at idle and in a lower portion of the operating range where a reduced amount of charging air is adequate, a secondary lower speed ratio is provided by the mechanical drive system. A speed responsive clutch is included to disconnect the higher speed primary drive during engine operation in the lower speed range and permit operation at the more efficient secondary speed ratio.

  18. Review of Test Procedure for Determining HSPFs of Residential Variable-Speed Heat Pumps

    SciTech Connect

    Rice, C. Keith; Munk, Jeffrey D.; Shrestha, Som S.

    2015-08-01

    This report reviews the suitability of the existing Heating Seasonal Performance Factor (HSPF) ratings and testing requirements for the current generation of variable-speed (VS) air-source heat pumps. Recent field test results indicate larger discrepancies between rated HSPF and field-observed HSPF for VS models than for single-speed models in the same houses. These findings suggest that the heating season test and ratings procedure should be revisited for VS heat pumps. The ratings and testing procedures are described in ANSI/AHRI 210/240 (2008) for single-speed, two-capacity, and variable-speed units. Analysis of manufacturer and independent test performance data on VS units reveals why the current VS testing/ratings procedure results in overly optimistic HSPF ratings for some VS units relative to other types of heat pumps. This is due to a combination of extrapolation of low speed test data beyond the originally anticipated ambient temperature operating range and the constraints of unit controls, which prevent low speed operation over the range of ambient temperatures assumed in the procedure for low speed. As a result, the HSPFs of such units are being overpredicted relative to those for single- and two-capacity designs. This overprediction has been found to be significantly reduced by use in the HSPF ratings procedure of an alternative higher-load heating load line, described in a companion report (Rice et al., 2015).

  19. Harnessing the damping properties of materials for high-speed atomic force microscopy.

    PubMed

    Adams, Jonathan D; Erickson, Blake W; Grossenbacher, Jonas; Brugger, Juergen; Nievergelt, Adrian; Fantner, Georg E

    2016-02-01

    The success of high-speed atomic force microscopy in imaging molecular motors, enzymes and microbes in liquid environments suggests that the technique could be of significant value in a variety of areas of nanotechnology. However, the majority of atomic force microscopy experiments are performed in air, and the tapping-mode detection speed of current high-speed cantilevers is an order of magnitude lower in air than in liquids. Traditional approaches to increasing the imaging rate of atomic force microscopy have involved reducing the size of the cantilever, but further reductions in size will require a fundamental change in the detection method of the microscope. Here, we show that high-speed imaging in air can instead be achieved by changing the cantilever material. We use cantilevers fabricated from polymers, which can mimic the high damping environment of liquids. With this approach, SU-8 polymer cantilevers are developed that have an imaging-in-air detection bandwidth that is 19 times faster than those of conventional cantilevers of similar size, resonance frequency and spring constant.

  20. Harnessing the damping properties of materials for high-speed atomic force microscopy.

    PubMed

    Adams, Jonathan D; Erickson, Blake W; Grossenbacher, Jonas; Brugger, Juergen; Nievergelt, Adrian; Fantner, Georg E

    2016-02-01

    The success of high-speed atomic force microscopy in imaging molecular motors, enzymes and microbes in liquid environments suggests that the technique could be of significant value in a variety of areas of nanotechnology. However, the majority of atomic force microscopy experiments are performed in air, and the tapping-mode detection speed of current high-speed cantilevers is an order of magnitude lower in air than in liquids. Traditional approaches to increasing the imaging rate of atomic force microscopy have involved reducing the size of the cantilever, but further reductions in size will require a fundamental change in the detection method of the microscope. Here, we show that high-speed imaging in air can instead be achieved by changing the cantilever material. We use cantilevers fabricated from polymers, which can mimic the high damping environment of liquids. With this approach, SU-8 polymer cantilevers are developed that have an imaging-in-air detection bandwidth that is 19 times faster than those of conventional cantilevers of similar size, resonance frequency and spring constant. PMID:26595334

  1. Harnessing the damping properties of materials for high-speed atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Adams, Jonathan D.; Erickson, Blake W.; Grossenbacher, Jonas; Brugger, Juergen; Nievergelt, Adrian; Fantner, Georg E.

    2016-02-01

    The success of high-speed atomic force microscopy in imaging molecular motors, enzymes and microbes in liquid environments suggests that the technique could be of significant value in a variety of areas of nanotechnology. However, the majority of atomic force microscopy experiments are performed in air, and the tapping-mode detection speed of current high-speed cantilevers is an order of magnitude lower in air than in liquids. Traditional approaches to increasing the imaging rate of atomic force microscopy have involved reducing the size of the cantilever, but further reductions in size will require a fundamental change in the detection method of the microscope. Here, we show that high-speed imaging in air can instead be achieved by changing the cantilever material. We use cantilevers fabricated from polymers, which can mimic the high damping environment of liquids. With this approach, SU-8 polymer cantilevers are developed that have an imaging-in-air detection bandwidth that is 19 times faster than those of conventional cantilevers of similar size, resonance frequency and spring constant.

  2. Extraction and Separation of Vitisin D, Ampelopsin B and cis-Vitisin A from Iris lactea Pall. var. chinensis (Fisch.) Koidz by Alkaline Extraction-Acid Precipitation and High-Speed Counter-Current Chromatography.

    PubMed

    Lv, Huanhuan; Zhou, Wenna; Wang, Xiaoyan; Wang, Zhenhua; Suo, Yourui; Wang, Honglun

    2016-01-01

    Naturally occurring oligostilbenes are receiving more attention because they exhibit several beneficial effects for health, including hepatoprotective, antitumor, anti-adipogenic, antioxidant, antiaging, anti-inflammatory, anti-microbial, antiviral, immunosuppressive and neuroprotective activities. Thus, they could be of some potentially therapeutic values for several diseases. In this study, we adopted the alkaline extraction-acid precipitation (AEAP) method for extraction of oligostilbenes from the seed kernel of Iris lactea Then, the high-speed counter-current chromatography (HSCCC) was used for preparative isolation and purification of oligostilbenes from the AEAP extracts. Finally, three oligostilbenes, namely vitisin D (73 mg), ampelopsin B (25 mg) and cis-vitisin A (16 mg), were successfully fractionated by HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (2:5:3:6, v/v/v/v) from 300 mg of the AEAP extracts in ∼ 190 min. The purities of the three isolated oligostilbenes were all over 95.0% as analyzed by high performance liquid chromatography. They all were isolated from I. lacteal for the first time.The method of AEAP for the preparation of the oligostilbene-enriched crude sample was simple, and the HSCCC technique for the isolation and purification of oligostilbenes was efficient.

  3. Application of high-speed counter-current chromatography combined with macroporous resin for rapid enrichment and separation of three anthraquinone glycosides and one stilbene glycoside from Rheum tanguticum.

    PubMed

    Chen, Tao; Liu, Yong-Ling; Chen, Chen; Zou, Deng-Lang; You, Jin-Mao; Sun, Jing; Li, Yu-Lin

    2014-04-15

    In this paper, an efficient method was successfully established by the combination of macroporous resin (MR) and high-speed counter-current chromatography (HSCCC) for rapid enrichment and separation of aloe-emodin 8-O-β-D-glucoside, emodin 1-O-β-D-glucoside, emodin 8-O-β-D-glucoside and piceatannol 4'-O-β-D-(6″-O-gallate)-glucoside. Six kinds of macroporous resins were investigated in the first step and X-5 macroporous resin was selected for the enrichment of the target compounds. The recoveries of the target compounds reached 89.0, 85.9, 82.3 and 84.9% respectively after 40% ethanol elution. In the second step, the target compounds were separated by HSCCC with a two-phase solvent system composed of chloroform/ethyl acetate/methanol/water (8:1:6:5, v/v). The established method will be helpful for further characterization and utilization of Rheum tanguticum. The results demonstrate that MR coupled with HSCCC is a powerful technique for separation of bioactive compounds from natural products.

  4. On-line purity monitoring in high-speed counter-current chromatography: application of HSCCC-HPLC-DAD for the preparation of 5-HMF, neomangiferin and mangiferin from Anemarrhena asphodeloides Bunge.

    PubMed

    Zhou, Tingting; Zhu, Zhenyu; Wang, Chen; Fan, Guorong; Peng, Jinyong; Chai, Yifeng; Wu, Yutian

    2007-05-01

    An efficient on-line purity monitoring strategy based on on-line coupling of high-speed counter-current chromatography (HSCCC) with high-performance liquid chromatography-diode array detection (HPLC-DAD) was successfully applied for the first time to the isolation and purification of 5-hydroxymethyl-furancarboxaldehyde (5-HMF), mangiferin and neomangiferin from the Chinese medicinal plant Anemarrhena asphodeloides Bunge, a plant used in the traditional Chinese medicine. The introduction of on-line purity monitoring in HSCCC has greatly improved the efficiency of this technique by overcoming the drawbacks of post-purification sample handling in HSCCC isolation. The effluent from the outlet of HSCCC was split into two parts, and one was collected, while the other was introduced directly through a switch valve into a HPLC-DAD system for purity monitoring. Using this method the desired fractions with high purities could be collected. From 600 mg partially purified extract, 165.6 mg neomangiferin and 292.8 mg mangiferin with purities of 98.9 and 99.5%, respectively, were obtained with a two-phase solvent system composed of n-butanol-water (1:1, v/v) by increasing the flow-rate of the mobile phase stepwise from 1.0 to 2.2 ml min(-1) after 210 min. A 17.1mg 5-HMF with purity of 96.6% was also isolated for the first time.

  5. Preparative isolation and purification of cuminaldehyde and p-menta-1,4-dien-7-al from the essential oil of Cuminum cyminum L. by high-speed counter-current chromatography.

    PubMed

    Chen, Qinqin; Hu, Xuefang; Li, Jingming; Liu, Ping; Yang, Yang; Ni, Yuanying

    2011-03-01

    High-speed counter-current chromatography (HSCCC) technique in semi-preparative scale was successfully used in isolation and purification of cuminaldehyde and p-menta-1,4-dien-7-al from the essential oil of Cuminum cyminum L. by using a two-phase solvent system composed of n-hexane-methanol-water (5:4:1, v/v/v). The targeted compounds were isolated, collected, purified by HSCCC in the head-tail mode, and then analyzed by gas chromatography (GC). A total of 12.72 ± 0.22 mg of cuminaldehyde and 10.61 ± 0.27 mg of p-menta-1,4-dien-7-al were obtained from 50 mg of the essential oil of C. cyminum L. in less than 6 h, with purities of 95.42% and 97.21%, respectively. In addition to GC-EI/MS, the identity of the cuminaldehyde was further confirmed with the retention time using the method of standard addition, while, the structural identification of p-menta-1,4-dien-7-al was performed with GC-EI/MS, (1)H NMR and (1)H-(1)H COSY.

  6. Separation and preparation of 6-gingerol from molecular distillation residue of Yunnan ginger rhizomes by high-speed counter-current chromatography and the antioxidant activity of ginger oils in vitro.

    PubMed

    Gan, Zhilin; Liang, Zheng; Chen, Xiaosong; Wen, Xin; Wang, Yuxiao; Li, Mo; Ni, Yuanying

    2016-02-01

    Molecular distillation residue (MD-R) from ginger had the most total phenol content of 247.6mg gallic acid equivalents per gram (GAE/g) among the ginger oils. High-speed counter-current chromatography (HSCCC) technique in semi-preparative scale was successfully performed in separation and purification of 6-gingerol from MD-R by using a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (10:2:5:7, v/v/v/v). The target compound was isolated, collected, purified by HSCCC in the head-tail mode, and then analyzed by HPLC. A total of 90.38±0.53mg 6-gingerol was obtained from 600mg MD-R, with purity of 99.6%. In addition, the structural identification of 6-gingerol was performed by EI/MS, (1)H NMR and (13)C NMR. Moreover, the orders of antioxidant activity were vitamin E (VE)>supercritical fluid extraction oleoresin (SFE-O)=MD-R=6-gingerol>molecular distillation essential oil (MD-EO) and butylated hydroxytoluene (BHT)=VE>6-gingerol>MD-R=SFE-O>MD-EO, respectively in 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging and β-Carotene bleaching.

  7. Extraction and Separation of Vitisin D, Ampelopsin B and cis-Vitisin A from Iris lactea Pall. var. chinensis (Fisch.) Koidz by Alkaline Extraction-Acid Precipitation and High-Speed Counter-Current Chromatography.

    PubMed

    Lv, Huanhuan; Zhou, Wenna; Wang, Xiaoyan; Wang, Zhenhua; Suo, Yourui; Wang, Honglun

    2016-01-01

    Naturally occurring oligostilbenes are receiving more attention because they exhibit several beneficial effects for health, including hepatoprotective, antitumor, anti-adipogenic, antioxidant, antiaging, anti-inflammatory, anti-microbial, antiviral, immunosuppressive and neuroprotective activities. Thus, they could be of some potentially therapeutic values for several diseases. In this study, we adopted the alkaline extraction-acid precipitation (AEAP) method for extraction of oligostilbenes from the seed kernel of Iris lactea Then, the high-speed counter-current chromatography (HSCCC) was used for preparative isolation and purification of oligostilbenes from the AEAP extracts. Finally, three oligostilbenes, namely vitisin D (73 mg), ampelopsin B (25 mg) and cis-vitisin A (16 mg), were successfully fractionated by HSCCC with a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (2:5:3:6, v/v/v/v) from 300 mg of the AEAP extracts in ∼ 190 min. The purities of the three isolated oligostilbenes were all over 95.0% as analyzed by high performance liquid chromatography. They all were isolated from I. lacteal for the first time.The method of AEAP for the preparation of the oligostilbene-enriched crude sample was simple, and the HSCCC technique for the isolation and purification of oligostilbenes was efficient. PMID:26847919

  8. Preparative isolation of four ginsenosides from Korean red ginseng (steam-treated Panax ginseng C. A. Meyer), by high-speed counter-current chromatography coupled with evaporative light scattering detection.

    PubMed

    Ha, Young Wan; Lim, Soon Sung; Ha, In Jin; Na, Yun-Cheol; Seo, Jung-Ju; Shin, Heungsop; Son, Sung Ho; Kim, Yeong Shik

    2007-06-01

    Ginseng (Panax ginseng C. A. Meyer) has been well known to have a variety of ginsenosides that show diverse biological activities. Especially, the components of ginsenosides are quite different depending on the processing method. Recently, there have been several reports showing that less polar ginsenosides from Korean red ginseng (steam-treated Panax ginseng) have potent biological activities such as radical scavenging, vasodilating and anti-tumor activities. In this study, we have isolated four known ginsenosides Rg3, Rk1, Rg5 and F4 from Korean red ginseng by high-speed counter-current chromatography (HSCCC) coupled with evaporative light scattering detection (ELSD). The enriched saponin fraction (350 mg) was separated by using methylene chloride-methanol-water-isopropanol (6:6:4:1, v/v) as the two-phase solvent system and yielded 28.6 mg of Rg5, 26.6 mg of Rk1, 32.2 mg of Rg3 and 8.1 mg of F4. The purity of these ginsenosides was assessed by HPLC-ELSD to be over 95%, and their structures were characterized by electrospray ionization mass spectrometry (ESI-MS), (1)H NMR and (13)C NMR.

  9. Separation and preparation of 6-gingerol from molecular distillation residue of Yunnan ginger rhizomes by high-speed counter-current chromatography and the antioxidant activity of ginger oils in vitro.

    PubMed

    Gan, Zhilin; Liang, Zheng; Chen, Xiaosong; Wen, Xin; Wang, Yuxiao; Li, Mo; Ni, Yuanying

    2016-02-01

    Molecular distillation residue (MD-R) from ginger had the most total phenol content of 247.6mg gallic acid equivalents per gram (GAE/g) among the ginger oils. High-speed counter-current chromatography (HSCCC) technique in semi-preparative scale was successfully performed in separation and purification of 6-gingerol from MD-R by using a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (10:2:5:7, v/v/v/v). The target compound was isolated, collected, purified by HSCCC in the head-tail mode, and then analyzed by HPLC. A total of 90.38±0.53mg 6-gingerol was obtained from 600mg MD-R, with purity of 99.6%. In addition, the structural identification of 6-gingerol was performed by EI/MS, (1)H NMR and (13)C NMR. Moreover, the orders of antioxidant activity were vitamin E (VE)>supercritical fluid extraction oleoresin (SFE-O)=MD-R=6-gingerol>molecular distillation essential oil (MD-EO) and butylated hydroxytoluene (BHT)=VE>6-gingerol>MD-R=SFE-O>MD-EO, respectively in 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) scavenging and β-Carotene bleaching. PMID:26773887

  10. Application of high-speed counter-current chromatography combined with macroporous resin for rapid enrichment and separation of three anthraquinone glycosides and one stilbene glycoside from Rheum tanguticum.

    PubMed

    Chen, Tao; Liu, Yong-Ling; Chen, Chen; Zou, Deng-Lang; You, Jin-Mao; Sun, Jing; Li, Yu-Lin

    2014-04-15

    In this paper, an efficient method was successfully established by the combination of macroporous resin (MR) and high-speed counter-current chromatography (HSCCC) for rapid enrichment and separation of aloe-emodin 8-O-β-D-glucoside, emodin 1-O-β-D-glucoside, emodin 8-O-β-D-glucoside and piceatannol 4'-O-β-D-(6″-O-gallate)-glucoside. Six kinds of macroporous resins were investigated in the first step and X-5 macroporous resin was selected for the enrichment of the target compounds. The recoveries of the target compounds reached 89.0, 85.9, 82.3 and 84.9% respectively after 40% ethanol elution. In the second step, the target compounds were separated by HSCCC with a two-phase solvent system composed of chloroform/ethyl acetate/methanol/water (8:1:6:5, v/v). The established method will be helpful for further characterization and utilization of Rheum tanguticum. The results demonstrate that MR coupled with HSCCC is a powerful technique for separation of bioactive compounds from natural products. PMID:24662143

  11. Development of an efficient method for the preparative isolation and purification of chlorophyll a from a marine dinoflagellate Amphidinium carterae by high-speed counter-current chromatography coupled with reversed-phase high-performance liquid chromatography.

    PubMed

    Long, Lijuan; Song, Yang; Wu, Jun; Lei, Li; Huang, Kai; Long, Benwen

    2006-12-01

    In our research into chlorophylls of marine dinoflagellates, chlorophyll a was separated rapidly from the hexane extract of Amphidinium carterae in three steps. The first step was silica gel column chromatography, where elution was performed with 0-50% ethyl acetate in n-hexane. The second was high-speed counter-current chromatography using a two-phase solvent system consisting of n-hexane-ethyl acetate-methanol-water (5:5:5:1, v/v), and the third step was preparative reversed-phase high-performance liquid chromatography using a solvent system of acetone-water (89:11, v/v). HPLC analysis showed that the purity of chlorophyll a from the second step was over 83%, and after the third it was over 99%. Thirty milligrams of chlorophyll a was isolated from a crude sample of 250 mg of chlorophylls, and its structure was identified by analyzing its MS, 1H NMR and 13C NMR spectra.

  12. Partition efficiencies of newly fabricated universal high-speed counter-current chromatograph for separation of two different types of sugar derivatives with organic-aqueous two-phase solvent systems

    PubMed Central

    Shinomiya, Kazufusa; Sato, Kazuki; Yoshida, Kazunori; Tokura, Koji; Maruyama, Hiroshi; Yanagidaira, Kazuhiro; Ito, Yoichiro

    2013-01-01

    Universal high-speed counter-current chromatograph (HSCCC) was newly designed and fabricated in our laboratory. It holds a set of four column holders symmetrically around the rotary frame at a distance of 11.2 cm from the central axis. By engaging the stationary gear on the central axis of the centrifuge to the planetary gears on the column holder shaft through a set of idle gears, two pairs of diagonally located column holders simultaneously rotate about their own axes in the opposite directions: one forward (type-J planetary motion) and the other backward (type-I planetary motion) each synchronously with the revolution. Using the eccentric coil assembly, partition efficiencies produced by these two planetary motions were compared on the separation of two different types of sugar derivatives (4-methylumbelliferyl and 5-bromo-4-chloro-3-indoxyl sugar derivatives) using organic-aqueous two-phase solvent systems composed of n-hexane/ethyl acetate/1-butanol/methanol/water and aqueous 0.1 M sodium tetraborate, respectively. With lower phase mobile, better peak resolution was obtained by the type-J forward rotation for both samples probably due to higher retention of the stationary phase. With upper phase mobile, however, similar peak resolutions were obtained between these two planetary motions for both sugar derivatives. The overall results indicate that the present universal HSCCC is useful for counter-current chromatographic separation since each planetary motion has its specific applications: e.g., vortex CCC by the type-I planetary motion and HSCCC by the type-J planetary motion both for separation of various natural and synthetic products. PMID:24267319

  13. Partition efficiencies of newly fabricated universal high-speed counter-current chromatograph for separation of two different types of sugar derivatives with organic-aqueous two-phase solvent systems.

    PubMed

    Shinomiya, Kazufusa; Sato, Kazuki; Yoshida, Kazunori; Tokura, Koji; Maruyama, Hiroshi; Yanagidaira, Kazuhiro; Ito, Yoichiro

    2013-12-27

    A new design of universal high-speed counter-current chromatograph (HSCCC) was fabricated in our laboratory. It holds a set of four column holders symmetrically around the rotary frame at a distance of 11.2cm from the central axis. By engaging the stationary gear on the central axis of the centrifuge to the planetary gears on the column holder shaft through a set of idle gears, two pairs of diagonally located column holders simultaneously rotate about their own axes in the opposite directions: one forward (type-J planetary motion) and the other backward (type-I planetary motion) each synchronously with the revolution. Using the eccentric coil assembly, partition efficiencies produced by these two planetary motions were compared on the separation of two different types of sugar derivatives (4-methylumbelliferyl and 5-bromo-4-chloro-3-indoxyl sugar derivatives) using organic-aqueous two-phase solvent systems composed of n-hexane/ethyl acetate/1-butanol/methanol/water and aqueous 0.1M sodium tetraborate, respectively. With lower phase mobile, better peak resolution was obtained by the type-J forward rotation for both samples probably due to higher retention of the stationary phase. With upper phase mobile, however, similar peak resolutions were obtained between these two planetary motions for both sugar derivatives. The overall results indicate that the present universal HSCCC is useful for counter-current chromatographic separation since each planetary motion has its specific applications: e.g., vortex CCC by the type-I planetary motion and HSCCC by the type-J planetary motion both for separation of various natural and synthetic products.

  14. Modeling Compressibility Effects in High-Speed Turbulent Flows

    NASA Technical Reports Server (NTRS)

    Sarkar, S.

    2004-01-01

    Man has strived to make objects fly faster, first from subsonic to supersonic and then to hypersonic speeds. Spacecraft and high-speed missiles routinely fly at hypersonic Mach numbers, M greater than 5. In defense applications, aircraft reach hypersonic speeds at high altitude and so may civilian aircraft in the future. Hypersonic flight, while presenting opportunities, has formidable challenges that have spurred vigorous research and development, mainly by NASA and the Air Force in the USA. Although NASP, the premier hypersonic concept of the eighties and early nineties, did not lead to flight demonstration, much basic research and technology development was possible. There is renewed interest in supersonic and hypersonic flight with the HyTech program of the Air Force and the Hyper-X program at NASA being examples of current thrusts in the field. At high-subsonic to supersonic speeds, fluid compressibility becomes increasingly important in the turbulent boundary layers and shear layers associated with the flow around aerospace vehicles. Changes in thermodynamic variables: density, temperature and pressure, interact strongly with the underlying vortical, turbulent flow. The ensuing changes to the flow may be qualitative such as shocks which have no incompressible counterpart, or quantitative such as the reduction of skin friction with Mach number, large heat transfer rates due to viscous heating, and the dramatic reduction of fuel/oxidant mixing at high convective Mach number. The peculiarities of compressible turbulence, so-called compressibility effects, have been reviewed by Fernholz and Finley. Predictions of aerodynamic performance in high-speed applications require accurate computational modeling of these "compressibility effects" on turbulence. During the course of the project we have made fundamental advances in modeling the pressure-strain correlation and developed a code to evaluate alternate turbulence models in the compressible shear layer.

  15. Aerodynamic Characteristics of Airfoils at High Speeds

    NASA Technical Reports Server (NTRS)

    Briggs, L J; Hull, G F; Dryden, H L

    1925-01-01

    This report deals with an experimental investigation of the aerodynamical characteristics of airfoils at high speeds. Lift, drag, and center of pressure measurements were made on six airfoils of the type used by the air service in propeller design, at speeds ranging from 550 to 1,000 feet per second. The results show a definite limit to the speed at which airfoils may efficiently be used to produce lift, the lift coefficient decreasing and the drag coefficient increasing as the speed approaches the speed of sound. The change in lift coefficient is large for thick airfoil sections (camber ratio 0.14 to 0.20) and for high angles of attack. The change is not marked for thin sections (camber ratio 0.10) at low angles of attack, for the speed range employed. At high speeds the center of pressure moves back toward the trailing edge of the airfoil as the speed increases. The results indicate that the use of tip speeds approaching the speed of sound for propellers of customary design involves a serious loss in efficiency.

  16. Period-speed analysis of a pendulum

    NASA Astrophysics Data System (ADS)

    Kostov, Yavor; Morshed, Ragib; Höling, Barbara; Chen, Ray; Siegel, P. B.

    2008-10-01

    We analyze a simple pendulum by measuring the period and the maximum speed of the bob. Both quantities are measured to high precision using a laser diode and an infrared photodetector located at the bottom of the pendulum. Expressing the period in terms of the maximum speed enables students to examine the large angle dependence of the period, and provides a method to calibrate the speed and do a detailed analysis of the effect of air friction on a sphere. We find that the force due to air friction is well described by a linear and quadratic term in the speed. We investigate the dependence of each term on the sphere's diameter for Reynolds numbers from 250 to 104.

  17. Speed Control of General Purpose Engine with Electronic Governor

    NASA Astrophysics Data System (ADS)

    Sawut, Umerujan; Tohti, Gheyret; Takigawa, Buso; Tsuji, Teruo

    This paper presents a general purpose engine speed control system with an electronic governor in order to improve the current system with a mechanical governor which shows unstable characteristics by change of mecanical friction or A/F ratio (Air/Fuel ratio). For the control system above, there are problems that the feedback signal is only a crank angle because of cost and the controlled object is a general purpose engine which is strongly nonlinear. In order to overcome these problems, the system model is shown for the dynamic estimation of the amount of air flow and the robust controller is designed. That is, the proposed system includes the robust sliding-mode controller by the feedback signal of only a crank angle where Genetic Algorithm is applied for the controller design. The simulation and the experiments by MATLAB/Simulink are performed to show the effectiveness of our proposal.

  18. Efficient preparation of pseudoalteromone A from marine Pseudoalteromonas rubra QD1-2 by combination of response surface methodology and high-speed counter-current chromatography: a comparison with high-performance liquid chromatography.

    PubMed

    Ding, Lijian; He, Shan; Yan, Xiaojun

    2014-05-01

    Pseudoalteromone A (PA) is a cytotoxic and anti-inflammatory ubiquinone discovered recently from a marine bacterium Pseudoalteromonas sp. CGH2XX. In order to meet its sample supply for further in vivo pharmacological investigation, an efficient method was developed for the preparation of PA by combination of response surface methodology (RSM) and high-speed counter-current chromatography (HSCCC) from marine bacterium P. rubra QD1-2. First, optimization of culture conditions was studied by the RSM to enhance PA production. The results indicated that the optimal cultivation condition was peptone (2.21 g/l), yeast extract (3.125 g/l), glucose (0.125 g/l), KBr (0.02 g/l), inoculum size (6.5 %), medium volume (595 ml), initial pH value (7.0), temperature (28 °C). Under the optimized fermentation condition, PA production was 1.04 mg/l with 14.8-fold increase comparing to 0.07 mg/l under original standard fermentation condition. The PA production was further investigated using a 14-l jar fermenter. Compared to the flask culture, P. rubra QD1-2 offered 45 % increase of PA production at 1.51 mg/l. Then, a rapid and efficient method for the separation and purification of PA from crude culture extract was developed using HSCCC. The two-phase solvent system used for HSCCC separation was composed of n-hexane-ethyl acetate-methanol-water (5:5:9:5, v/v/v/v). The isolation was accomplished within 100 min, and the purity of PA was over 95 %. The recovery of the process was 93 %.

  19. High-speed counter-current chromatography coupled online to high performance liquid chromatography-diode array detector-mass spectrometry for purification, analysis and identification of target compounds from natural products.

    PubMed

    Liang, Xuejuan; Zhang, Yuping; Chen, Wei; Cai, Ping; Zhang, Shuihan; Chen, Xiaoqin; Shi, Shuyun

    2015-03-13

    A challenge in coupling high-speed counter-current chromatography (HSCCC) online with high performance liquid chromatography (HPLC) for purity analysis was their time incompatibility. Consequently, HSCCC-HPLC was conducted by either controlling HPLC analysis time and HSCCC flow rate or using stop-and-go scheme. For natural products containing compounds with a wide range of polarities, the former would optimize experimental conditions, while the latter required more time. Here, a novel HSCCC-HPLC-diode array detector-mass spectrometry (HSCCC-HPLC-DAD-MS) was developed for undisrupted purification, analysis and identification of multi-compounds from natural products. Two six-port injection valves and a six-port switching valve were used as interface for collecting key HSCCC effluents alternatively for HPLC-DAD-MS analysis and identification. The ethyl acetate extract of Malus doumeri was performed on the hyphenated system to verify its efficacy. Five main flavonoids, 3-hydroxyphloridzin (1), phloridzin (2), 4',6'-dihydroxyhydrochalcone-2'-O-β-D-glucopyranoside (3, first found in M. doumeri), phloretin (4), and chrysin (5), were purified with purities over 99% by extrusion elution and/or stepwise elution mode in two-step HSCCC, and 25mM ammonium acetate solution was selected instead of water to depress emulsification in the first HSCCC. The online system shortened manipulation time largely compared with off-line analysis procedure and stop-and-go scheme. The results indicated that the present method could serve as a simple, rapid and effective way to achieve target compounds with high purity from natural products.

  20. Preparative isolation and purification of five steroid saponins from Dioscorea zingiberensis C.H.Wright by high-speed counter-current chromatography coupled with evaporative light scattering detector

    PubMed Central

    Zhang, Xinxin; Liang, Jinru; Ito, Yoichiro; Zhang, Yongmin; Liu, Jianli; Sun, Wenji

    2013-01-01

    A high-speed counter current chromatography (HSCCC) method was successfully applied to separate and purify steroid saponins from the traditional Chinese medicine Dioscorea zingiberensis C.H.Wright for the first time. Ethyl cetate-n-butanol-methanol-water (4:1:2:4, v/v) was used as the two-phase solvent system, and evaporative light scattering detector (ELSD) was used as the detector in this method. The method separated in a single run the following five steroid saponins: 26-O-β-D-glucopyranosyl-(25R)-furost- 5-en-3β,22ζ,26-triol-3- O-[β-D-glucopyranosyl-(1→3)-β-D-glucopyranol- (1→4)-α-L-rhamnopyranosyl-(1→2)]-β-D-glucopyranoside (Compound A); 26-O-β-D-glucopyranosyl-(25R)-furost-5-en-3β,22ζ,26- triol-3-O-[β-D-glucopyranosyl (1→3)-α-L-rhamnopyranosyl(1→2)]-β-D-glucopyranoside (Compound B); 26-O-β-D-glucopyranosyl-(25R)-furost-5-en-3β, 22ζ, 26-triol- 3-O- [α-L-rhamnopyranosyl (1→4)]-β-D-glucopyranoside (Compound C); 26- O-β-D- glucopyranosyl- (25R)- furost-5, 20(22)-diene-3β, 26-diol-3-O-{α-L-rhamnopyranosyl- (1→4)-[β-D-glucopyranosyl-(1→3)-β-D-glucopyranosyl-(1→2)]}-β-D-glucopyranoside (Compound D); and 26-O-β-D-glucopyranosyl-(25R)-furost-5, 20(22)-diene-3β, 26-diol-3 -O-[β-D-glucopyranosyl- (1→4)-α-L-rhamnopyranosyl(1→2)]-β-D-glucopyranoside (Compound E). Their structural identification of the five steroid saponins was performed by means of ESI-MS, and 13C NMR. PMID:23831486

  1. Separation and purification of bovine serum albumin binders from Fructus polygoni orientalis using off-line two-dimensional complexation high-speed counter-current chromatography target-guided by ligand fishing.

    PubMed

    Liu, Qi; Shi, Shuyun; Liu, Liangliang; Yang, Hua; Su, Wen; Chen, Xiaoqing

    2013-08-23

    In this study, off-line two-dimensional (2D) complexation high speed counter-current chromatography (HSCCC) was developed for the separation of bovine serum albumin (BSA) binders from the ethyl acetate extract of Fructus polygoni orientalis. Target-guided strategy of BSA functionalized iron oxide magnetic nanoparticles coupled with high performance liquid chromatography-tandem mass spectrometry ((BSA-Fe3O4 MNPs)-HPLC-MS/MS) experiment was proposed. In the orthogonal separation system, a Normal-Phase HSCCC with 0.01mol/L copper ion as complexation agent in the aqueous phase was employed for the first dimension and Recycling HSCCC, Reverse-Phase HSCCC with 0.1mol/L copper ion were used for the second dimension in parallel. Including two pairs of cis-trans isomers, seven BSA binders including 3,5,7-Trihydroxychromone (1), taxifolin (2), N-cis-paprazine (3), N-cis-feruloyltyramine (4), N-trans-paprazine (5), N-trans-feruloyltyramine (6) and an unidentified compound (7) were obtained. The purities of these seven compounds were all over 95.0% as determined by HPLC. The complexation HSCCC behaviors of seven compounds were also investigated by studying their relationship with copper ion. Results showed that the combinative method using (BSA-Fe3O4 MNPs)-HPLC and HSCCC is a quick, efficient, and reproductive technique to isolate potentially bioactive compounds from the complex mixture system of natural products. And the usage of off-line 2D-HSCCC and introduction of chelating metal ion into solvent system are effective ways to implement HSCCC separations in complex samples.

  2. Profiling the fatty acids from a strain of the microalgae Alexandrium tamarense by means of high-speed counter-current chromatography and gas chromatography coupled with mass spectrometry.

    PubMed

    Hammann, Simon; Tillmann, Urban; Schröder, Markus; Vetter, Walter

    2013-10-18

    Fatty acids of microalgae have been studied as potential chemotaxonomic markers, to reveal plausible lipid phycotoxins or in the context of mass production of algal biofuels. The planctonic microalgae Alexandrium tamarense (Dinophyceae) is a common harmful algal bloom species that often proliferates in eutrophic costal waters. Alexandrium blooms are the proximal source of toxins associated with paralytic shellfish poisoning (PSP), a neurological affliction that has caused human illness for centuries via consumption of contaminated shellfish. However, data on the fatty acid composition of A. tamarense is currently limited. For this reason, we cultivated a well-defined strain of A. tamarense (Alex2, group I, North American clade) in order to study both its major and minor fatty acids. The harvested microalgae were transesterified and the fatty acid methyl esters were fractionated by means of high-speed counter-current chromatography (HSCCC). The resulting 31 HSCCC fractions were analyzed by gas chromatography with mass spectrometry (GC/MS). Unknown substances were identified by transferring assorted HSCCC fractions into picolinyl or pyrrolidide derivatives. Twenty fatty acids (range 0.2-22.9% contribution to total fatty acids) were identified in the unfractionated sample with 14:0, 16:0, 18:1n-9, 18:4n-3, 18:5n-3 and 22:6n-3 representing>80% of the total fatty acids. HSCCC fractionation enabled the identification of further 22 trace fatty acids contributing between ∼0.01 and 0.2% to total fatty acids. The fatty acids included several branched-chain fatty acids as well as scarcely reported fatty acids like 11-methyl-18:1n-6tr or 18:2Δ4,9. In order to enable a better comparability and repeatability of HSCCC fractionations, we calculated for each HSCCC fraction the total volume of mobile phase, which had passed the HSCCC. From this volume we subtracted the volume of extruded stationary phase and divided the corrected volume by the total coil volume. These elution

  3. High speed handpieces.

    PubMed

    Bhandary, Nayan; Desai, Asavari; Shetty, Y Bharath

    2014-02-01

    High speed instruments are versatile instruments used by clinicians of all specialties of dentistry. It is important for clinicians to understand the types of high speed handpieces available and the mechanism of working. The centers for disease control and prevention have issued guidelines time and again for disinfection and sterilization of high speed handpieces. This article presents the recent developments in the design of the high speed handpieces. With a view to prevent hospital associated infections significant importance has been given to disinfection, sterilization & maintenance of high speed handpieces. How to cite the article: Bhandary N, Desai A, Shetty YB. High speed handpieces. J Int Oral Health 2014;6(1):130-2.

  4. Subsurface evaluation of the west parking lot and landfill 3 areas of Air Force Plant 4, Fort Worth, Texas, using two-dimensional direct-current resistivity profiling

    USGS Publications Warehouse

    Braun, Christopher L.; Jones, Sonya A.

    2002-01-01

    During September 1999, the U.S. Geological Survey made 10 two-dimensional direct-current resistivity profile surveys in the west parking lot and landfill 3 areas of Air Force Plant 4, Fort Worth, Texas, to identify subsurface areas of anomalously high or low resistivity that could indicate potential contamination, contaminant pathways, or anthropogenic structures. Six of the 10 surveys (transects) were in the west parking lot. Each of the inverted sections of these transects had anomalously high resistivities in the terrace alluvium/fill (the surficial subsurface layer) that probably were caused by highly resistive fill material. In addition, each of these transects had anomalously low resistivities in the Walnut Formation (a bedrock layer immediately beneath the alluvium/fill) that could have been caused by saturation of fractures within the Walnut Formation. A high-resistivity anomaly in the central part of the study area probably is associated with pea gravel fill used in construction of a French drain. Another high resistivity anomaly in the west parking lot, slightly southeast of the French drain, could be caused by dense nonaqueous-phase liquid in the Walnut Formation. The inverted sections of the four transects in the landfill 3 area tended to have slightly higher resistivities in both the alluvium/fill and the Walnut Formation than the transects in the west parking lot. The higher resistivities in the alluvium/fill could have been caused by drier conditions in grassy areas relative to conditions in the west parking lot. Higher resistivities in parts of the Walnut Formation also could be a function of drier conditions or variations in the lithology of the Walnut Formation. In addition to the 10 vertical sections, four horizontal sections at 2-meteraltitude intervals show generally increasing resistivity with decreasing altitude that most likely results from the increased influence of the Walnut Formation, which has a higher resistivity than the terrace

  5. Vehicle speed control device

    SciTech Connect

    Thornton-Trump, W.E.

    1987-03-10

    An apparatus is described for automatically limiting the speed of a vehicle powered by an internal combustion engine having a spark ignition system with an ignition coil, comprising: sensor means for generating a speed signal directly representative of the speed of the vehicle comprising a series of speed signal pulses having a pulse repetition frequency proportional to the speed of the vehicle; control means for converting speed signal pulses into a DC voltage proportional to the vehicle speed; means for comparing the DC voltage to a predetermined DC voltage having substantially zero AC components representative of a predetermined maximum speed and for generating a difference signal in response thereto; and means for generating a pulse-width modulated control signal responsive to the difference signal; power means responsive to the control signal for intermittently interrupting the ignition system.

  6. Rotary Speed Sensor for Antilocking Brakes

    NASA Technical Reports Server (NTRS)

    Berdahl, C. M.

    1986-01-01

    Sensor based on fluidic principles produces negative pressure approximately proportional to rotational speed. Sensor developed as part of antilocking brake system for motorcycles. Uses inlet pressure rather than outlet pressure as braking-control signal, eliminating pressure pulsations caused by pump vanes and ensuring low-noise signal. Sensor is centrifugal air pump turned by one of motorcycle wheels. Air enters pump through orifice plates, and suction taken off through port in pump inlet plenum.

  7. Separation and purification of α-glucosidase inhibitors from Polygonatum odoratum by stepwise high-speed counter-current chromatography combined with Sephadex LH-20 chromatography target-guided by ultrafiltration-HPLC screening.

    PubMed

    Zhou, Xiaoling; Liang, Junsheng; Zhang, Yi; Zhao, Huading; Guo, Ying; Shi, Shuyun

    2015-03-15

    Although Polygonatum odoratum has been widely used as medicinal plant and food supplement for treating diabetes, little is known regarding its bioactive components. In this study, ultrafiltration-HPLC based ligand screening was developed to screen α-glucosidase inhibitors from P. odoratum for the first time. Then bioactive components were target-guided separated by combining stepwise high-speed counter-current chromatography (HSCCC) using petroleum ether-ethyl acetate-methanol-water (1:4:0.8:4.2, v/v/v/v), (1:4:1.8:3.2, v/v/v/v) and (1:4:2.3:2.7, v/v/v/v) as solvent systems with Sephadex LH-20 chromatography eluted by MeCN-MeOH (1:1, v/v). Five phenethyl cinnamides, N-cis-feruloyloctopamine (1); N-trans-p-coumaroyloctopamine (2), N-trans-feruloyloctopamine (3), N-trans-p-coumaroyltyramine (4) and N-trans-feruloyltyramine (5), and four homoisoflavanones, (3R)-5,7-dihydroxyl-3-(2',4'-dihydroxylbenzyl)-chroman-4-one (6), (3R)-5,7-dihydroxyl-6-methyl-3-(4'-hydroxylbenzyl)-chroman-4-one (7), (3R)-5,7-dihydroxyl-6-methyl-8-methoxyl-3-(4'-hydroxylbenzyl)-chroman-4-one (8); and (3R)-5,7-dihydroxyl-6,8-dimethyl-3-(4'-hydroxylbenzyl)-chroman-4-one) (9), with purity over 98.5% were purified, and their structures were identified by UV, MS, and (1)H NMR. Notably, compounds 2 and 4 were first reported in genus Polygonatum, while compound 1 was first obtained from family Liliaceae. In addition, α-glucosidase inhibitory activities of compounds 1-9 were evaluated, and compounds 2 and 4 exhibited stronger α-glucosidase inhibitory activity with IC50 values of 2.3 and 2.7μM. The results suggested the potential medicinal use of P. odoratum, and the technology could be widely applied for rapid screening and preparative separation of a group of bioactive compounds from complex matrix.

  8. Optimization of the Ultrasonic-Assisted Extraction of Bioactive Flavonoids from Ampelopsis grossedentata and Subsequent Separation and Purification of Two Flavonoid Aglycones by High-Speed Counter-Current Chromatography.

    PubMed

    Zhang, Hongbing; Xie, Guoyong; Tian, Mei; Pu, Qian; Qin, Minjian

    2016-01-01

    The fermented leaf of Ampelopsis grossedentata has been used as a beverage and folk medicine called "vine tea" in the southern region of China. In this paper, the optimum extraction conditions for the maximum recovery amounts of total flavonoids (TF), dihydromyricetin (DMY), myricitrin (MYG) and myricetin (MY) from natural Ampelopsis grossedentata leaves subjected to ultrasonic-assisted extraction (UAE) were determined and optimized by using response surface methodology. The method was employed by the Box-Behnken design (BBD) and Derringer's desirability function using methanol concentration, extraction time, liquid/solid ratio as factors and the contents of TF, DMY, MYG and MY as responses. The obtained optimum UAE conditions were as follows: a solvent of 80.87% methanol, an extraction time of 31.98 min and a liquid/solid ratio of 41.64:1 mL/g. Through analysis of the response surface, it implied that methanol concentration and the liquid/solid ratio had significant effects on TF, DMY, MYG and MY yields, whereas extraction time had relatively little effects. The established extraction and analytical methods were successfully applied to determine the contents of the total flavonoids and three individual flavonoids in 10 batches of the leaf samples of A. grossedentata from three counties in Fujian Province, China. The results suggested the variability in the quality of A. grossedentata leaves from different origins. In addition, high purities of dihydromyricetin and myricetin were simultaneously separated and purified from the extract subjected to optimized UAE, by high-speed counter-current chromatography using a solvent system of N-hexane-ethyl acetate-methanol-water (1:3:2:4; v/v/v/v). In a single operation, 200 mg of the extract were separated to yield 86.46 mg of dihydromyricetin and 3.61 mg of myricetin with the purity of 95.03% and 99.21%, respectively. The results would be beneficial for further exploiting the herbal products and controlling the quality of

  9. Preparative separation and identification of novel subsidiary colors of the color additive D&C Red No. 33 (Acid Red 33) using spiral high-speed counter-current chromatography☆

    PubMed Central

    Weisz, Adrian; Ridge, Clark D.; Mazzola, Eugene P.; Ito, Yoichiro

    2015-01-01

    Three low-level subsidiary color impurities (A, B, and C) often present in batches of the color additive D&C Red No. 33 (R33, Acid Red 33, Colour Index No. 17200) were separated from a portion of R33 by spiral high-speed counter-current chromatography (HSCCC). The separation involved use of a very polar solvent system, 1-BuOH/5 mM aq. (NH4)2SO4. Addition of ammonium sulfate to the lower phase forced partition of the components into the upper phase, thereby eliminating the need to add a hydrophobic counterion as was previously required for separations of components from sulfonated dyes. The very polar solvent system used would not have been retained in a conventional multi-layer coil HSCCC instrument, but the spiral configuration enabled retention of the stationary phase, and thus, the separation was possible. A 1 g portion of R33 enriched in A, B, and C was separated using the upper phase of the solvent system as the mobile phase. The retention of the stationary phase was 38.1%, and the separation resulted in 4.8 mg of A of >90% purity, 18.3 mg of B of >85% purity, and 91 mg of C of 65–72% purity. A second separation of a portion of the C mixture resulted in 7 mg of C of >94% purity. The separated impurities were identified by high-resolution mass spectrometry and NMR spectroscopic techniques as follows: 5-amino-3-biphenyl-3-ylazo-4-hydroxy-naphthalene-2,7-disulfonic acid, A; 5-amino-4-hydroxy-6-phenyl-3-phenylazo-naphthalene-2,7-disulfonic acid, B; and 5-amino-4-hydroxy-3,6-bis-phenylazo-naphthalene-2,7-disulfonic acid, C. The isomers A and B are compounds reported for the first time. Application of the spiral HSCCC method resulted in the additional benefit of yielding 930 mg of the main component of R33, 5-amino-4-hydroxy-3-phenylazo-naphthalene-2,7-disulfonic acid, of >97% purity. PMID:25591404

  10. Preparative separation and identification of novel subsidiary colors of the color additive D&C Red No. 33 (Acid Red 33) using spiral high-speed counter-current chromatography.

    PubMed

    Weisz, Adrian; Ridge, Clark D; Mazzola, Eugene P; Ito, Yoichiro

    2015-02-01

    Three low-level subsidiary color impurities (A, B, and C) often present in batches of the color additive D&C Red No. 33 (R33, Acid Red 33, Colour Index No. 17200) were separated from a portion of R33 by spiral high-speed counter-current chromatography (HSCCC). The separation involved use of a very polar solvent system, 1-BuOH/5mM aq. (NH4)2SO4. Addition of ammonium sulfate to the lower phase forced partition of the components into the upper phase, thereby eliminating the need to add a hydrophobic counterion as was previously required for separations of components from sulfonated dyes. The very polar solvent system used would not have been retained in a conventional multi-layer coil HSCCC instrument, but the spiral configuration enabled retention of the stationary phase, and thus, the separation was possible. A 1g portion of R33 enriched in A, B, and C was separated using the upper phase of the solvent system as the mobile phase. The retention of the stationary phase was 38.1%, and the separation resulted in 4.8 mg of A of >90% purity, 18.3mg of B of >85% purity, and 91 mg of C of 65-72% purity. A second separation of a portion of the C mixture resulted in 7 mg of C of >94% purity. The separated impurities were identified by high-resolution mass spectrometry and NMR spectroscopic techniques as follows: 5-amino-3-biphenyl-3-ylazo-4-hydroxy-naphthalene-2,7-disulfonic acid, A; 5-amino-4-hydroxy-6-phenyl-3-phenylazo-naphthalene-2,7-disulfonic acid, B; and 5-amino-4-hydroxy-3,6-bis-phenylazo-naphthalene-2,7-disulfonic acid, C. The isomers A and B are compounds reported for the first time. Application of the spiral HSCCC method resulted in the additional benefit of yielding 930 mg of the main component of R33, 5-amino-4-hydroxy-3-phenylazo-naphthalene-2,7-disulfonic acid, of >97% purity.

  11. High speed civil transport

    NASA Technical Reports Server (NTRS)

    1991-01-01

    This report discusses the design and marketability of a next generation supersonic transport. Apogee Aeronautics Corporation has designated its High Speed Civil Transport (HSCT): Supercruiser HS-8. Since the beginning of the Concorde era, the general consensus has been that the proper time for the introduction of a next generation Supersonic Transport (SST) would depend upon the technical advances made in the areas of propulsion (reduction in emissions) and material composites (stronger, lighter materials). It is believed by many in the aerospace industry that these beforementioned technical advances lie on the horizon. With this being the case, this is the proper time to begin the design phase for the next generation HSCT. The design objective for a HSCT was to develop an aircraft that would be capable of transporting at least 250 passengers with baggage at a distance of 5500 nmi. The supersonic Mach number is currently unspecified. In addition, the design had to be marketable, cost effective, and certifiable. To achieve this goal, technical advances in the current SST's must be made, especially in the areas of aerodynamics and propulsion. As a result of these required aerodynamic advances, several different supersonic design concepts were reviewed.

  12. The evolution of the high-speed civil transport

    NASA Technical Reports Server (NTRS)

    Spearman, M. Leroy

    1994-01-01

    Current research directed toward the technology requirements for a high-speed civil transport (HSCT) airplane is an outgrowth of many years of activity related to air transportation. The purpose was to review some of the events that provided the background upon which current research programs are built. The review will include the subsonic era of transport aircraft and some events of the supersonic era that are related to the development of commercial supersonic transport aircraft. These events include the early NASA in-house studies and industry evaluations, the U.S. Supersonic Transport (SST) Program, the follow-on NASA supersonic cruise research programs, and the issuance of the National Aeronautical Research and Development (R&D) goals. Observations are made concerning some of the factors, both technical and nontechnical, that have had an impact on HSCT studies.

  13. The Speed of Light in Different Media.

    ERIC Educational Resources Information Center

    Feldman, Allan

    1991-01-01

    A procedure for measuring the speed of light using the assumption that the frequency of light remains unchanged as it moves from one medium to another is presented. A laser with a known wavelength and frequency in air was used as a light source. (KR)

  14. Air surveillance

    SciTech Connect

    Patton, G.W.

    1995-06-01

    This section of the 1994 Hanford Site Environmental Report summarizes the air surveillance and monitoring programs currently in operation at that Hanford Site. Atmospheric releases of pollutants from Hanford to the surrounding region are a potential source of human exposure. For that reason, both radioactive and nonradioactive materials in air are monitored at a number of locations. The influence of Hanford emissions on local radionuclide concentrations was evaluated by comparing concentrations measured at distant locations within the region to concentrations measured at the Site perimeter. This section discusses sample collection, analytical methods, and the results of the Hanford air surveillance program. A complete listing of all analytical results summarized in this section is reported separately by Bisping (1995).

  15. High speed handpieces

    PubMed Central

    Bhandary, Nayan; Desai, Asavari; Shetty, Y Bharath

    2014-01-01

    High speed instruments are versatile instruments used by clinicians of all specialties of dentistry. It is important for clinicians to understand the types of high speed handpieces available and the mechanism of working. The centers for disease control and prevention have issued guidelines time and again for disinfection and sterilization of high speed handpieces. This article presents the recent developments in the design of the high speed handpieces. With a view to prevent hospital associated infections significant importance has been given to disinfection, sterilization & maintenance of high speed handpieces. How to cite the article: Bhandary N, Desai A, Shetty YB. High speed handpieces. J Int Oral Health 2014;6(1):130-2. PMID:24653618

  16. Vehicle speed control system

    SciTech Connect

    Yoshida, D.; Tanno, T.; Fukunaga, T.

    1987-06-16

    This patent describes a vehicle speed control system for performing vehicle speed control by controlling the displacement of at least one of a hydraulic pump and a hydraulic motor of a hydraulic transmission through an electric servo device, comprising: vehicle speed setting means for generating a voltage signal corresponding to a vehicle speed to be set; compensating means interposed between the vehicle speed setting means and the electric servo device, the compensating means comprising a first delay element; and second delay element having a response characteristic slower than that of the first delay element. A selecting means for judging as to whether a voltage signal changed by the operation of the vehicle speed setting means represents an acceleration command or a deceleration command and for selecting the first delay element when the voltage signal represents an acceleration command and for selecting the second delay element when the voltage signal represents a deceleration command.

  17. 'What price speed', revisited

    NASA Astrophysics Data System (ADS)

    Teitler, S.; Proodian, R. E.

    1980-02-01

    An attempt is made to examine fuel transport effectiveness as a function of vehicle cruise velocity, when studying limits in speed beyond which a particular form of locomotion becomes inefficient and economically unattractive. Attention is given to the Dix-Riddell relationship and to the specific fuel energy expenditure ratio. It is concluded that for each value of speed at which useful work is carried out, there is an experiential maximum that sets the standard for fuel transport effectiveness at that speed.

  18. 46 CFR 154.1864 - Vessel speed within speed reduction.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Vessel speed within speed reduction. 154.1864 Section... Vessel speed within speed reduction. The master shall ensure that the speed of the vessel is not greater than the posted speed reduction....

  19. 46 CFR 154.1864 - Vessel speed within speed reduction.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Vessel speed within speed reduction. 154.1864 Section... Vessel speed within speed reduction. The master shall ensure that the speed of the vessel is not greater than the posted speed reduction....

  20. 46 CFR 154.1864 - Vessel speed within speed reduction.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Vessel speed within speed reduction. 154.1864 Section... Vessel speed within speed reduction. The master shall ensure that the speed of the vessel is not greater than the posted speed reduction....

  1. 46 CFR 154.1864 - Vessel speed within speed reduction.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Vessel speed within speed reduction. 154.1864 Section... Vessel speed within speed reduction. The master shall ensure that the speed of the vessel is not greater than the posted speed reduction....

  2. 46 CFR 154.1864 - Vessel speed within speed reduction.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Vessel speed within speed reduction. 154.1864 Section... Vessel speed within speed reduction. The master shall ensure that the speed of the vessel is not greater than the posted speed reduction....

  3. SU-E-P-15: Technique Factor Modulation and Reference Plane Air Kerma Rates in Response to Simulated Patient Thickness Variations for a Sample of Current Generation Fluoroscopes

    SciTech Connect

    Wunderle, K; Rakowski, J; Dong, F

    2015-06-15

    Purpose: To evaluate and compare approaches to technique factor modulation and air kerma rates in response to simulated patient thickness variations for four state-of-the-art and one previous-generation interventional fluoroscopes. Methods: A polymethyl methacrylate (PMMA) phantom was used as a tissue surrogate for the purposes of determining fluoroscopic reference plane air kerma rates, kVp, mA, and spectral filtration over a wide range of simulated tissue thicknesses. Data were acquired for each fluoroscopic and acquisition dose curve within a default abdomen or body imaging protocol. Results: The data obtained indicated vendor- and model-specific variations in the approach to technique factor modulation and reference plane air kerma rates across a range of tissue thicknesses. Some vendors have made hardware advances increasing the radiation output capabilities of their fluoroscopes; this was evident in the acquisition air kerma rates. However, in the imaging protocol evaluated, all of the state-of-the-art systems had relatively low air kerma rates in the fluoroscopic low-dose imaging mode as compared to the previous-generation unit. Each of the newest-generation systems also employ copper filtration in the selected protocol in the acquisition mode of imaging; this is a substantial benefit, reducing the skin entrance dose to the patient in the highest dose-rate mode of fluoroscope operation. Conclusion: Understanding how fluoroscopic technique factors are modulated provides insight into the vendor-specific image acquisition approach and provides opportunities to optimize the imaging protocols for clinical practice. The enhanced radiation output capabilities of some of the fluoroscopes may, under specific conditions, may be beneficial; however, these higher output capabilities also have the potential to lead to unnecessarily high dose rates. Therefore, all parties involved in imaging, including the clinical team, medical physicists, and imaging vendors, must work

  4. Nonintrusive shaft speed sensor

    NASA Technical Reports Server (NTRS)

    Barkhoudarian, S.; Wyett, L.; Maram, J.

    1985-01-01

    Reusable rocket engines such as the Space Shuttle Main Engines (SSME), the Orbital Transfer Vehicles (OTV), etc., have throttling capabilities that require real-time, closed-loop control systems of engine propellant flows, combustion temperatures and pressures, and turbopump rotary speeds. In the case of the SSME, there are four turbopumps that require real-time measurement and control of their rotary speeds. Variable-reluctance magnetic speed sensors were designed, fabricated, and tested for all four turbopumps, resulting in the successful implementation and operation of three of these speed sensors during each of the 12 Shuttle flights.

  5. Multiple current peaks in room-temperature atmospheric pressure homogenous dielectric barrier discharge plasma excited by high-voltage tunable nanosecond pulse in air

    SciTech Connect

    Yang, De-Zheng; Wang, Wen-Chun; Zhang, Shuai; Tang, Kai; Liu, Zhi-jie; Wang, Sen

    2013-05-13

    Room temperature homogenous dielectric barrier discharge plasma with high instantaneous energy efficiency is acquired by using nanosecond pulse voltage with 20-200 ns tunable pulse width. Increasing the voltage pulse width can lead to the generation of regular and stable multiple current peaks in each discharge sequence. When the voltage pulse width is 200 ns, more than 5 organized current peaks can be observed under 26 kV peak voltage. Investigation also shows that the organized multiple current peaks only appear in homogenous discharge mode. When the discharge is filament mode, organized multiple current peaks are replaced by chaotic filament current peaks.

  6. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Generation of currents and propagation of plasma fronts in the case of two-pulse interaction with a target in air

    NASA Astrophysics Data System (ADS)

    Barkhudarov, É. M.; Gelashvili, G. V.; Gumberidze, G. G.; Taktakishvili, M. I.

    1990-06-01

    An investigation was made of the enhancement in the efficiency of generation of currents when a target in air was subjected to two consecutive CO2 laser radiation pulses. Preliminary interaction with a low-energy (1.5-5 J) pulse increased by more than one order of magnitude the currents generated by the second pulse and this was true in a wide range of energies of the latter pulse. The energy conversion efficiency was practically unaffected. The results were in qualitative agreement with the proposed pattern of plasma formation and propagation of shock waves near a target.

  7. Dynamic simulation of dual-speed wind turbine generation

    SciTech Connect

    Muljadi, E; Butterfield, C P

    1996-10-01

    Induction generators have been used since the early development of utility-scale wind turbine generation. An induction generator is the generator of choice because of its ruggedness, and low cost. With an induction generator, the operating speed of the wind turbine is limited to a narrow range (almost constant speed). Dual- speed operation can be accomplished by using an induction generator with two different sets of winding configurations or by using two induction generators with two different rated speeds. With single- speed operation, the wind turbine operates at different power coefficients (Cp) as the wind speed varies. The operation at maximum Cp can occur only at a single wind speed. However, if the wind speed varies across a wider range, the operating Cp will vary significantly. Dual-speed operation has the advantage of enabling the wind turbine to operate at near maximum Cp over a wider range of wind-speeds. Thus, annual energy production can be increased. The dual-speed mode may generate less energy than a variable-speed mode; nevertheless, it offers an alternative to capture more energy than single-speed operation. In this paper, dual-speed operation of a wind turbine will be investigated. One type of control algorithm for dual- speed operation is proposed. Results from a dynamic simulation will be presented to show how the control algorithm works and how power, current and torque of the system vary as the wind turbine is exposed to varying wind speeds.

  8. Can anti-speeding messages based on protection motivation theory influence reported speeding intentions?

    PubMed

    Glendon, A Ian; Walker, Britta L

    2013-08-01

    The study investigated the effects of anti-speeding messages based on protection motivation theory (PMT) components: severity, vulnerability, rewards, self-efficacy, response efficacy, and response cost, on reported speeding intentions. Eighty-three participants aged 18-25 years holding a current Australian driver's license completed a questionnaire measuring their reported typical and recent speeding behaviors. Comparisons were made between 18 anti-speeding messages used on Australian roads and 18 new anti-speeding messages developed from the PMT model. Participants reported their reactions to the 36 messages on the perceived effectiveness of the message for themselves and for the general population of drivers, and also the likelihood of themselves and other drivers driving within the speed limit after viewing each message. Overall the PMT model-derived anti-speeding messages were better than jurisdiction-use anti-speeding messages in influencing participants' reported intention to drive within the speed limit. Severity and vulnerability were the most effective PMT components for developing anti-speeding messages. Male participants reported significantly lower intention to drive within the speed limit than did female participants. However, males reported significantly higher intention to drive within the speed limit for PMT-derived messages compared with jurisdiction-based messages. Third-person effects were that males reported anti-speeding messages to be more effective for the general driving population than for themselves. Females reported the opposite effect - that all messages would be more effective for themselves than for the general driving population. Findings provided support for using a sound conceptual basis as an effective foundation for anti-speeding message development as well as for evaluating proposed anti-speeding messages on the target driver population.

  9. Can anti-speeding messages based on protection motivation theory influence reported speeding intentions?

    PubMed

    Glendon, A Ian; Walker, Britta L

    2013-08-01

    The study investigated the effects of anti-speeding messages based on protection motivation theory (PMT) components: severity, vulnerability, rewards, self-efficacy, response efficacy, and response cost, on reported speeding intentions. Eighty-three participants aged 18-25 years holding a current Australian driver's license completed a questionnaire measuring their reported typical and recent speeding behaviors. Comparisons were made between 18 anti-speeding messages used on Australian roads and 18 new anti-speeding messages developed from the PMT model. Participants reported their reactions to the 36 messages on the perceived effectiveness of the message for themselves and for the general population of drivers, and also the likelihood of themselves and other drivers driving within the speed limit after viewing each message. Overall the PMT model-derived anti-speeding messages were better than jurisdiction-use anti-speeding messages in influencing participants' reported intention to drive within the speed limit. Severity and vulnerability were the most effective PMT components for developing anti-speeding messages. Male participants reported significantly lower intention to drive within the speed limit than did female participants. However, males reported significantly higher intention to drive within the speed limit for PMT-derived messages compared with jurisdiction-based messages. Third-person effects were that males reported anti-speeding messages to be more effective for the general driving population than for themselves. Females reported the opposite effect - that all messages would be more effective for themselves than for the general driving population. Findings provided support for using a sound conceptual basis as an effective foundation for anti-speeding message development as well as for evaluating proposed anti-speeding messages on the target driver population. PMID:23643708

  10. Current challenges in modelling far-range air pollution induced by the 2014-2015 Bárðarbunga fissure eruption (Iceland)

    NASA Astrophysics Data System (ADS)

    Boichu, Marie; Chiapello, Isabelle; Brogniez, Colette; Péré, Jean-Christophe; Thieuleux, Francois; Torres, Benjamin; Blarel, Luc; Mortier, Augustin; Podvin, Thierry; Goloub, Philippe; Söhne, Nathalie; Clarisse, Lieven; Bauduin, Sophie; Hendrick, François; Theys, Nicolas; Van Roozendael, Michel; Tanré, Didier

    2016-08-01

    The 2014-2015 Holuhraun lava-flood eruption of Bárðarbunga volcano (Iceland) emitted prodigious amounts of sulfur dioxide into the atmosphere. This eruption caused a large-scale episode of air pollution throughout Western Europe in September 2014, the first event of this magnitude recorded in the modern era. We gathered chemistry-transport simulations and a wealth of complementary observations from satellite sensors (OMI, IASI), ground-based remote sensing (lidar, sunphotometry, differential optical absorption spectroscopy) and ground-level air quality monitoring networks to characterize both the spatial-temporal distributions of volcanic SO2 and sulfate aerosols as well as the dynamics of the planetary boundary layer. Time variations of dynamical and microphysical properties of sulfate aerosols in the aged low-tropospheric volcanic cloud, including loading, vertical distribution, size distribution and single scattering albedo, are provided. Retrospective chemistry-transport simulations at low horizontal resolution (25 km × 25 km) capture the correct temporal dynamics of this far-range air pollution event but fail to reproduce the correct magnitude of SO2 concentration at ground-level. Simulations at higher spatial resolution, relying on two nested domains with finest resolution of 7.3 km × 7.3 km, improve substantially the far-range vertical distribution of the volcanic cloud and subsequently the description of ground-level SO2 concentrations. However, remaining discrepancies between model and observations are shown to result from an inaccurate representation of the planetary boundary layer (PBL) dynamics. Comparison with lidar observations points out a systematic under-estimation of the PBL height by the model, whichever the PBL parameterization scheme. Such a shortcoming impedes the capture of the overlying Bárðarbunga cloud into the PBL at the right time and in sufficient quantities. This study therefore demonstrates the key role played by the PBL

  11. Atari: Speed Reading.

    ERIC Educational Resources Information Center

    Oliver, Steve

    1983-01-01

    Reviews "Atari Speed Reading" course materials (which include eight units on four cassettes, 200-page workbook, and cassette with pacer/timer program). Indicates that the course is successful in meeting its goal to help average readers double their reading speed and comprehension. (JN)

  12. Speed Listening and Reading.

    ERIC Educational Resources Information Center

    Bradtmueller, Weldon G.

    Compressed speech (speed listening), in which audiotapes are speeded up, is examined in this paper along with its relationship to the reading process. Among the topics discussed first are the close relationship between reading and listening, the rationale behind compressed speech, and the use of compressed speech in business communication, special…

  13. Magnetically Coupled Adjustable Speed Motor Drives - Motor Tip Sheet #13

    SciTech Connect

    2008-07-01

    Alternating current electric motors rotate at a nearly constant speed that is determined by motor design and line frequency. Energy savings of 50% or more may be available when fixed speed systems are modified to allow the motor speed to match variable load requirements of a centrifugal fan or pump.

  14. 77 FR 1513 - Air Show and Air Races; Public Hearing

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-10

    ... From the Federal Register Online via the Government Publishing Office NATIONAL TRANSPORTATION SAFETY BOARD Air Show and Air Races; Public Hearing TIME AND DATE: 9 a.m., Tuesday, January 10, 2012... hearing is to examine current regulations and oversight practices for air shows and air races,...

  15. The magnitude and spatial range of current-use urban PCB and PBDE emissions estimated using a coupled multimedia and air transport model.

    PubMed

    Csiszar, Susan A; Diamond, Miriam L; Daggupaty, Sreerama M

    2014-01-21

    SO-MUM, a coupled atmospheric transport and multimedia urban model, was used to estimate spatially resolved (5 × 5 km(2)) air emissions and chemical fate based on measured air concentrations and chemical mass inventories within Toronto, Canada. Approximately 95% and 70% of Σ5PCBs (CB-28, -52, -101, -153, and -180) and Σ5PBDEs (BDE-28, -47, -100, -154, and -183) emissions of 17 (2-36) and 18 (3-42) kg y(-1), respectively, undergo atmospheric transport from the city, which is partly over Lake Ontario. The urban air plume was found to reach about 50 km for PCBs and PBDEs, in the direction of prevailing winds which is almost twice the distance of the wind-independent plume. The distance traveled by the plume is a function of prevailing wind velocity, the geographic distribution of the chemical inventory, and gas-particle partitioning. Soil wash-off of historically accumulated Σ5PCBs to surface water contributed ∼ 0.4 kg y(-1) (of mainly higher congeners) to near-shore Lake Ontario compared with volatilization of ∼ 6 kg y(-1) of mainly lighter congeners. Atmospheric emissions from primary sources followed by deposition to surface films and subsequent wash-off to surface water contributed ∼ 1 kg y(-1) and was the main route of Σ5PBDE loadings to near-shore Lake Ontario which acts as a net PBDE sink. Secondary emissions of PCBs and PBDEs from at least a ∼ 900,000 km(2) rural land area would be needed to produce the equivalent primary emissions as Toronto (∼ 640 km(2)). These results provide clear support for reducing inventories of these POPs.

  16. How well do stomatal conductance models perform on closing plant carbon budgets? A test using seedlings grown under current and elevated air temperatures

    NASA Astrophysics Data System (ADS)

    Way, Danielle A.; Oren, Ram; Kim, Hyun-Seok; Katul, Gabriel G.

    2011-12-01

    Future carbon and water fluxes within terrestrial ecosystems will be determined by how stomatal conductance (gs) responds to rising atmospheric CO2and air temperatures. While both short- and long-term CO2 effects on gs have been repeatedly studied, there are few studies on how gs acclimates to higher air temperatures. Six gs models were parameterized using leaf gas exchange data from black spruce (Picea mariana) seedlings grown from seed at ambient (22/16°C day/night) or elevated (30/24°C) air temperatures. Model performance was independently assessed by how well carbon gain from each model reproduced estimated carbon costs to close the seedlings' seasonal carbon budgets, a `long-term' indicator of success. A model holding a constant intercellular to ambient CO2ratio and the Ball-Berry model (based on stomatal responses to relative humidity) could not close the carbon balance for either treatment, while the Jarvis-Oren model (based on stomatal responses to vapor pressure deficit,D) and a model assuming a constant gs each closed the carbon balance for one treatment. Two models, both based on gs responses to D, performed best overall, estimating carbon uptake within 10% of carbon costs for both treatments: the Leuning model and a linear optimization model that maximizes carbon gain per unit water loss. Since gsresponses in the optimization model are not a priori assumed, this approach can be used in modeling land-atmosphere exchange of CO2 and water in future climates.

  17. Procedure for Determining Speed and Climbing Performance of Airships

    NASA Technical Reports Server (NTRS)

    Thompson, F L

    1936-01-01

    The procedure for obtaining air-speed and rate-of-climb measurements in performance tests of airships is described. Two methods of obtaining speed measurements, one by means of instruments in the airship and the other by flight over a measured ground course, are explained. Instruments, their calibrations, necessary correction factors, observations, and calculations are detailed for each method, and also for the rate-of-climb tests. A method of correction for the effect on density of moist air and a description of other methods of speed course testing are appended.

  18. Optical air data systems and methods

    NASA Technical Reports Server (NTRS)

    Caldwell, Loren M. (Inventor); Tang, Shoou-yu (Inventor); O'Brien, Martin (Inventor)

    2010-01-01

    Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip.

  19. Optical air data systems and methods

    NASA Technical Reports Server (NTRS)

    Caldwell, Loren M. (Inventor); O'Brien, Martin J. (Inventor); Weimer, Carl S. (Inventor); Nelson, Loren D. (Inventor)

    2005-01-01

    Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip.

  20. Optical air data systems and methods

    NASA Technical Reports Server (NTRS)

    Caldwell, Loren M. (Inventor); O'Brien, Martin J. (Inventor); Weimer, Carl S. (Inventor); Nelson, Loren D. (Inventor)

    2008-01-01

    Systems and methods for sensing air outside a moving aircraft are presented. In one embodiment, a system includes a laser for generating laser energy. The system also includes one or more transceivers for projecting the laser energy as laser radiation to the air. Subsequently, each transceiver receives laser energy as it is backscattered from the air. A computer processes signals from the transceivers to distinguish molecular scattered laser radiation from aerosol scattered laser radiation and determines one or more air parameters based on the scattered laser radiation. Such air parameters may include air speed, air pressure, air temperature and aircraft orientation angle, such as yaw, angle of attack and sideslip.

  1. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, ... Ozone, a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  2. Experimenting with End-Correction and the Speed of Sound

    ERIC Educational Resources Information Center

    LoPresto, Michael C.

    2011-01-01

    What follows is an alternative to the standard tuning fork and quarter-wave tube speed of sound experiment. Rather than adjusting the water level in a glass or plastic tube to vary the length of an air column, a set of resonance tubes of different lengths is used. The experiment still demonstrates the principles of standing waves in air columns…

  3. Superplane!High Speed Civil Transport

    NASA Technical Reports Server (NTRS)

    1998-01-01

    The High Speed Civil Transport (HSCT). This light-hearted promotional piece explains what the HSCT 'Superplane' is and what advantages it will have over current aircraft. As envisioned, the HSCT is a next-generation supersonic (faster than the speed of sound) passenger jet that would fly 300 passengers at more than 1,500 miles per hour -- more than twice the speed of sound. It will cross the Pacific or Atlantic in less than half the time of modern subsonic jets, and at a ticket price less than 20 percent above comparable, slower flights

  4. Current status of persistent organic pesticides residues in air, water, and soil, and their possible effect on neighboring countries: a comprehensive review of India.

    PubMed

    Yadav, Ishwar Chandra; Devi, Ningombam Linthoingambi; Syed, Jabir Hussain; Cheng, Zhineng; Li, Jun; Zhang, Gan; Jones, Kevin C

    2015-04-01

    Though the use of pesticides has offered significant economic benefits by enhancing the production and yield of food and fibers and the prevention of vector-borne diseases, evidence suggests that their use has adversely affected the health of human populations and the environment. Pesticides have been widely distributed and their traces can be detected in all areas of the environment (air, water and soil). Despite the ban of DDT and HCH in India, they are still in use, both in domestic and agricultural settings. In this comprehensive review, we discuss the production and consumption of persistent organic pesticides, their maximum residual limit (MRL) and the presence of persistent organic pesticides in multicomponent environmental samples (air, water and soil) from India. In order to highlight the global distribution of persistent organic pesticides and their impact on neighboring countries and regions, the role of persistent organic pesticides in Indian region is reviewed. Based on a review of research papers and modeling simulations, it can be concluded that India is one of the major contributors of global persistent organic pesticide distribution. This review also considers the health impacts of persistent organic pesticides, the regulatory measures for persistent organic pesticides, and the status of India's commitment towards the elimination of persistent organic pesticides.

  5. Air cushion craft development, first revision

    NASA Astrophysics Data System (ADS)

    Mantle, P. J.

    1980-01-01

    The development of air cushion craft from their inception to the present day is described. Both aerostatic craft known as air cushion vehicles and surface effect ships as well as aerodynamic craft such as wing-in-ground effect vehicles are covered. The various available theories, empirical laws, and experimental data were brought together and expressed in unified form. Emphasis is given to reducing the data and analysis to their simplest forms for easy understanding and isolation of fundamental parameters. Currently operational craft, those still in their construction jigs, or in some cases those still on the drawing board are assessed and compared to the basic theories to give a measure of the state-of-the-art. Such topics as performance, propulsion, ride quality, and high speed aerodynamic craft are included.

  6. High-Speed Photography

    SciTech Connect

    Paisley, D.L.; Schelev, M.Y.

    1998-08-01

    The applications of high-speed photography to a diverse set of subjects including inertial confinement fusion, laser surgical procedures, communications, automotive airbags, lightning etc. are briefly discussed. (AIP) {copyright} {ital 1998 Society of Photo-Optical Instrumentation Engineers.}

  7. SPEEDES benchmarking analysis

    NASA Astrophysics Data System (ADS)

    Capella, Sebastian J.; Steinman, Jeffrey S.; McGraw, Robert M.

    2002-07-01

    SPEEDES, the Synchronous Parallel Environment for Emulation and Discrete Event Simulation, is a software framework that supports simulation applications across parallel and distributed architectures. SPEEDES is used as a simulation engine in support of numerous defense projects including the Joint Simulation System (JSIMS), the Joint Modeling And Simulation System (JMASS), the High Performance Computing and Modernization Program's (HPCMP) development of a High Performance Computing (HPC) Run-time Infrastructure, and the Defense Modeling and Simulation Office's (DMSO) development of a Human Behavioral Representation (HBR) Testbed. This work documents some of the performance metrics obtained from benchmarking the SPEEDES Simulation Framework with respect to the functionality found in the summer of 2001. Specifically this papers the scalability of SPEEDES with respect to its time management algorithms and simulation object event queues with respect to the number of objects simulated and events processed.

  8. High Speed Research Program

    NASA Technical Reports Server (NTRS)

    Anderson, Robert E.; Corsiglia, Victor R.; Schmitz, Frederic H. (Technical Monitor)

    1994-01-01

    An overview of the NASA High Speed Research Program will be presented from a NASA Headquarters perspective. The presentation will include the objectives of the program and an outline of major programmatic issues.

  9. High Speed Ice Friction

    NASA Astrophysics Data System (ADS)

    Seymour-Pierce, Alexandra; Sammonds, Peter; Lishman, Ben

    2014-05-01

    Many different tribological experiments have been run to determine the frictional behaviour of ice at high speeds, ostensibly with the intention of applying results to everyday fields such as winter tyres and sports. However, experiments have only been conducted up to linear speeds of several metres a second, with few additional subject specific studies reaching speeds comparable to these applications. Experiments were conducted in the cold rooms of the Rock and Ice Physics Laboratory, UCL, on a custom built rotational tribometer based on previous literature designs. Preliminary results from experiments run at 2m/s for ice temperatures of 271 and 263K indicate that colder ice has a higher coefficient of friction, in accordance with the literature. These results will be presented, along with data from further experiments conducted at temperatures between 259-273K (in order to cover a wide range of the temperature dependent behaviour of ice) and speeds of 2-15m/s to produce a temperature-velocity-friction map for ice. The effect of temperature, speed and slider geometry on the deformation of ice will also be investigated. These speeds are approaching those exhibited by sports such as the luge (where athletes slide downhill on an icy track), placing the tribological work in context.

  10. Method and system for controlling a rotational speed of a rotor of a turbogenerator

    SciTech Connect

    Stahlhut, Ronnie Dean; Vuk, Carl Thomas

    2008-12-30

    A system and method controls a rotational speed of a rotor or shaft of a turbogenerator in accordance with a present voltage level on a direct current bus. A lower threshold and a higher threshold are established for a speed of a rotor or shaft of a turbogenerator. A speed sensor determines speed data or a speed signal for the rotor or shaft associated with a turbogenerator. A voltage regulator adjusts a voltage level associated with a direct current bus within a target voltage range if the speed data or speed signal indicates that the speed is above the higher threshold or below the lower threshold.

  11. How well do stomatal conductance models perform on closing plant carbon budgets? A test using seedlings grown under current and elevated air temperatures

    NASA Astrophysics Data System (ADS)

    Way, D.; Oren, R.; Kim, H.; Katul, G. G.

    2011-12-01

    Future carbon and water fluxes within terrestrial ecosystems will be determined by how stomatal conductance (gs) responds to rising atmospheric CO2 and air temperatures. While both short- and long-term CO2 effects on gs have been repeatedly studied, there are few studies on how gs acclimates to higher air temperatures. Six gs models were parameterized using leaf gas exchange data from black spruce (Picea mariana) seedlings grown from seed at ambient (22/16 °C day/night) or elevated (30/24 °C) temperatures. Model performance was independently assessed by how well carbon gain from each model reproduced estimated carbon costs to close the seedlings' seasonal carbon budgets, an indicator of the model success at time scales commensurate with biomass changes. A model holding a constant intercellular to ambient CO2 concentration ratio and the Ball-Berry model (based on stomatal responses to relative humidity) could not close the carbon balance for either treatment, while a so-called Jarvis-Oren model (based on stomatal responses to vapor pressure deficit, D) and a model assuming a constant gs each closed the carbon balance for one temperature treatment. Two models, both based on gs responses to D, performed best overall, estimating carbon uptake within 10% of carbon costs for both treatments: the Leuning model (a semi-empirical model that links gs to photosynthetic rates) and a linear optimization model that maximizes carbon gain per unit water loss. Since gs responses in the linear optimization model are not a priori assumed, this approach may be advantageous in modeling gs responses to temperature, especially in future climates.

  12. Changing speed-VMT distributions: the effects on emissions inventories and conformity.

    PubMed

    Nanzetta, K; Niemeier, D; Utts, J M

    2000-03-01

    The emissions factor modeling component of the motor vehicle emissions inventory (MVEI) modeling suite is currently being revised by the California Air Resources Board (CARB). One of the proposed changes in modeling philosophy is a shift from using link-based travel activity data to trip-based travel data for preparing mobile emissions inventories. Also as part of the revisions, new speed correction factors (SCFs) will be developed by CARB for the revised model. The new SCFs will be derived from vehicle emissions on 15 new driving cycles, each constructed to represent a typical trip at a specific average speed. This paper discusses how the new SCFs will affect transportation conformity and emissions inventory development, and evaluates the differences in total emissions produced by trip-based and link-based distributions of speed and vehicle miles of travel (VMT). We simulated both link-based and trip-based speed-VMT distributions using travel data from the Sacramento and San Diego travel demand models. On the basis of the simulation results, there is reason to expect that mobile emissions inventories constructed using the proposed trip-based philosophy will differ markedly from those constructed in the current manner. Noting that results may vary by region, increases are expected in the CO and HC inventory levels, with concomitant decreases in the NOx mobile emissions inventories.

  13. Quiet High-Speed Fan

    NASA Technical Reports Server (NTRS)

    Lieber, Lysbeth; Repp, Russ; Weir, Donald S.

    1996-01-01

    A calibration of the acoustic and aerodynamic prediction methods was performed and a baseline fan definition was established and evaluated to support the quiet high speed fan program. A computational fluid dynamic analysis of the NASA QF-12 Fan rotor, using the DAWES flow simulation program was performed to demonstrate and verify the causes of the relatively poor aerodynamic performance observed during the fan test. In addition, the rotor flowfield characteristics were qualitatively compared to the acoustic measurements to identify the key acoustic characteristics of the flow. The V072 turbofan source noise prediction code was used to generate noise predictions for the TFE731-60 fan at three operating conditions and compared to experimental data. V072 results were also used in the Acoustic Radiation Code to generate far field noise for the TFE731-60 nacelle at three speed points for the blade passage tone. A full 3-D viscous flow simulation of the current production TFE731-60 fan rotor was performed with the DAWES flow analysis program. The DAWES analysis was used to estimate the onset of multiple pure tone noise, based on predictions of inlet shock position as a function of the rotor tip speed. Finally, the TFE731-60 fan rotor wake structure predicted by the DAWES program was used to define a redesigned stator with the leading edge configured to minimize the acoustic effects of rotor wake / stator interaction, without appreciably degrading performance.

  14. Multi-year air monitoring of legacy and current-use brominated flame retardants in an urban center in northeastern China.

    PubMed

    Li, Wen-Long; Huo, Chun-Yan; Liu, Li-Yan; Song, Wei-Wei; Zhang, Zi-Feng; Ma, Wan-Li; Qiao, Li-Na; Li, Yi-Fan

    2016-11-15

    The occurrence and temporal trends of polybrominated diphenyl ethers (PBDEs) and non-PBDE brominated flame retardants (NBFRs) were investigated in an urban atmosphere of Northeast China in consecutive six years (2008-2013). Among all chemicals, BDE-209, l,2,5,6,9,10-hexabromocyclododecane (HBCD), and decabromodiphenylethane (DBDPE) were the three most dominant compounds. During the period, the levels of pentabromodiphenyl ethers in the gas-phase and octabromodiphenyl ethers in the particle-phase significantly decreased, while the levels of BDE-209 and NBFRs increased in either the gas-phase or particle-phase. Ambient temperature was the most significant variable that influenced the gas-phase and particle-phase concentrations of BFRs, followed by wind speed and relative humidity. A stronger temperature dependence of the atmospheric concentrations was found for lower mass BFRs. Gas-particle partitioning studies suggested PBDEs in the urban atmosphere of Northeast China were at steady-state. Steady-state equation can also well describe the partitioning behavior for NBFRs, suggesting that the atmospheric partitioning behaviors of NBFRs were similar to those of PBDEs.

  15. Multi-year air monitoring of legacy and current-use brominated flame retardants in an urban center in northeastern China.

    PubMed

    Li, Wen-Long; Huo, Chun-Yan; Liu, Li-Yan; Song, Wei-Wei; Zhang, Zi-Feng; Ma, Wan-Li; Qiao, Li-Na; Li, Yi-Fan

    2016-11-15

    The occurrence and temporal trends of polybrominated diphenyl ethers (PBDEs) and non-PBDE brominated flame retardants (NBFRs) were investigated in an urban atmosphere of Northeast China in consecutive six years (2008-2013). Among all chemicals, BDE-209, l,2,5,6,9,10-hexabromocyclododecane (HBCD), and decabromodiphenylethane (DBDPE) were the three most dominant compounds. During the period, the levels of pentabromodiphenyl ethers in the gas-phase and octabromodiphenyl ethers in the particle-phase significantly decreased, while the levels of BDE-209 and NBFRs increased in either the gas-phase or particle-phase. Ambient temperature was the most significant variable that influenced the gas-phase and particle-phase concentrations of BFRs, followed by wind speed and relative humidity. A stronger temperature dependence of the atmospheric concentrations was found for lower mass BFRs. Gas-particle partitioning studies suggested PBDEs in the urban atmosphere of Northeast China were at steady-state. Steady-state equation can also well describe the partitioning behavior for NBFRs, suggesting that the atmospheric partitioning behaviors of NBFRs were similar to those of PBDEs. PMID:27401280

  16. On The Vertical Speeds Of Airways Traffic

    NASA Astrophysics Data System (ADS)

    Magill, S. A. N.

    Knowledge of the statistics of aircraft vertical speeds is important both for the construction of realistic traffic simulators and for the development of trajectory prediction tools for use in future air traffic control (ATC) systems. This paper reports on the analysis of radar data recordings for nearly 10000 civil flights on airways. Results are presented for the means and spreads of vertical speeds as functions of altitude. Evidence is presented that roughly half of the observed spreads arise from fluctuations within each aircraft's trajectory, as opposed to variation from one aircraft to another. A simple procedure is proposed for simulating vertical speed data which has statistics similar to those obtained from the radar recordings. Some consequences of the results for the development of trajectory prediction tools for use in future ATC systems are discussed. The results suggest that the provision of accurate trajectory prediction tools is not as straightforward as it might at first appear to be.

  17. 40 CFR 86.161-00 - Air conditioning environmental test facility ambient requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... impractical, air flow of 2 mph or less will be allowed at 0 mph vehicle speed. (3) The fan air flow velocity vector perpendicular to the axial flow velocity vector shall be less than 10 percent of the mean velocity measured at fan speeds corresponding to vehicle speeds of 20 and 40 mph. (4)(i) Fan axial air flow...

  18. Speed Reading Scores in Perspective

    ERIC Educational Resources Information Center

    Smith, Brenda Golembesky

    1975-01-01

    Cites the factors that influence reading rates and comprehension scores on timed speed reading tests, concluding that the reading speed achieved for any particular test or timed reading is the speed for that situation only. (RB)

  19. Speed Reading: Remember the Tortoise

    ERIC Educational Resources Information Center

    Graf, Richard G.

    1973-01-01

    After speed-reading partisans questioned the criticisms in a Psychology Today article, another psychologist conducted a controlled study of speed readers. As we said before, "Speed Readers Don't Read; They Skim". (Editor)

  20. Everyone Deserves a Speeding Ticket.

    ERIC Educational Resources Information Center

    Burris, Harold

    1993-01-01

    Presents a first day physics activity having students determine the fine for a speeding ticket if the speeds considered include the earth's rotation and revolution speed, and the movement through the galaxy. (MDH)

  1. Advanced Air Data Systems for Commercial Aircraft

    NASA Technical Reports Server (NTRS)

    2006-01-01

    It is possible to get a crude estimate of wind speed and direction while driving a car at night in the rain, with the motion of the raindrop reflections in the headlights providing clues about the wind. The clues are difficult to interpret, though, because of the relative motions of ground, car, air, and raindrops. More subtle interpretation is possible if the rain is replaced by fog, because the tiny droplets would follow the swirling currents of air around an illuminated object, like, for example, a walking pedestrian. Microscopic particles in the air (aerosols) are better for helping make assessments of the wind, and reflective air molecules are best of all, providing the most refined measurements. It takes a bright light to penetrate fog, so it is easy to understand how other factors, like replacing the headlights with the intensity of a searchlight, can be advantageous. This is the basic principle behind a lidar system. While a radar system transmits a pulse of radiofrequency energy and interprets the received reflections, a lidar system works in a similar fashion, substituting a near-optical laser pulse. The technique allows the measurement of relative positions and velocities between the transmitter and the air, which allows measurements of relative wind and of air temperature (because temperature is associated with high-frequency random motions on a molecular level). NASA, as well as the National Oceanic and Atmospheric Administration (NOAA), have interests in this advanced lidar technology, as much of their explorative research requires the ability to measure winds and turbulent regions within the atmosphere. Lidar also shows promise for providing warning of turbulent regions within the National Airspace System to allow commercial aircraft to avoid encounters with turbulence and thereby increase the safety of the traveling public. Both agencies currently employ lidar and optical sensing for a variety of weather-related research projects, such as analyzing

  2. Released air during vapor and air cavitation

    NASA Astrophysics Data System (ADS)

    Jablonská, Jana; Kozubková, Milada

    2016-06-01

    Cavitation today is a very important problem that is solved by means of experimental and mathematical methods. The article deals with the generation of cavitation in convergent divergent nozzle of rectangular cross section. Measurement of pressure, flow rate, temperature, amount of dissolved air in the liquid and visualization of cavitation area using high-speed camera was performed for different flow rates. The measurement results were generalized by dimensionless analysis, which allows easy detection of cavitation in the nozzle. For numerical simulation the multiphase mathematical model of cavitation consisting of water and vapor was created. During verification the disagreement with the measurements for higher flow rates was proved, therefore the model was extended to multiphase mathematical model (water, vapor and air), due to release of dissolved air. For the mathematical modeling the multiphase turbulence RNG k-ɛ model for low Reynolds number flow with vapor and air cavitation was used. Subsequently the sizes of the cavitation area were verified. In article the inlet pressure and loss coefficient depending on the amount of air added to the mathematical model are evaluated. On the basis of the approach it may be create a methodology to estimate the amount of released air added at the inlet to the modeled area.

  3. Propagation or failure of detonation across an air gap in an LX-17 column: continuous time-dependent detonation or shock speed using the Embedded Fiber Optic (EFO) technique

    SciTech Connect

    Hare, D E; Chandler, J B; Compton, S M; Garza, R G; Grimsley, D A; Hernandez, A; Villafana, R J; Wade, J T; Weber, S R; Wong, B M; Souers, P C

    2008-01-16

    The detailed history of the shock/detonation wave propagation after crossing a room-temperature-room-pressure (RTP) air gap between a 25.4 mm diameter LX-17 donor column and a 25.4 mm diameter by 25.4 mm long LX-17 acceptor pellet is investigated for three different gap widths (3.07, 2.08, and 0.00 mm) using the Embedded Fiber Optic (EFO) technique. The 2.08 mm gap propagated and the 3.07 mm gap failed and this can be seen clearly and unambiguously in the EFO data even though the 25.4 mm-long acceptor pellet would be considered quite short for a determination by more traditional means such as pins.

  4. Actual and 'optimum' flight speeds: field data reassessed

    PubMed

    Pennycuick

    1997-01-01

    Previously published field observations of the air speeds of 36 species of birds, all observed by the same method (ornithodolite), were compared with estimates of the corresponding minimum power speeds, calculated with a default body drag coefficient of 0.1. This value, which was derived from recent wind tunnel studies, represents a downward revision from default values previously used and leads, in turn, to an upward revision of estimated minimum power speeds. The mean observed air speeds are now distributed around the minimum power speed, rather than in between the speeds for minimum power and maximum range, as they were before. Although the field data do not represent migration, examination of the marginal effects of small changes of speed, on power and lift:drag ratio, indicates that flying at the maximum range speed on migration may not represent an 'optimal' or even a practical strategy and that cruising speeds may be limited by the muscle power available or by aerobic capacity. Caution in constructing 'optimisation' theories is indicated.

  5. Apparatus and method for controlling the rotary airlocks in a coal processing system by reversing the motor current rotating the air lock

    DOEpatents

    Groombridge, Clifton E.

    1996-01-01

    An improvement to a coal processing system where hard materials found in the coal may cause jamming of either inflow or outflow rotary airlocks, each driven by a reversible motor. The instantaneous current used by the motor is continually monitored and compared to a predetermined value. If an overcurrent condition occurs, indicating a jamming of the airlock, a controller means starts a "soft" reverse rotation of the motor thereby clearing the jamming. Three patterns of the motor reversal are provided.

  6. Multiple Running Speed Signals in Medial Entorhinal Cortex.

    PubMed

    Hinman, James R; Brandon, Mark P; Climer, Jason R; Chapman, G William; Hasselmo, Michael E

    2016-08-01

    Grid cells in medial entorhinal cortex (MEC) can be modeled using oscillatory interference or attractor dynamic mechanisms that perform path integration, a computation requiring information about running direction and speed. The two classes of computational models often use either an oscillatory frequency or a firing rate that increases as a function of running speed. Yet it is currently not known whether these are two manifestations of the same speed signal or dissociable signals with potentially different anatomical substrates. We examined coding of running speed in MEC and identified these two speed signals to be independent of each other within individual neurons. The medial septum (MS) is strongly linked to locomotor behavior, and removal of MS input resulted in strengthening of the firing rate speed signal, while decreasing the strength of the oscillatory speed signal. Thus, two speed signals are present in MEC that are differentially affected by disrupted MS input. PMID:27427460

  7. Air Entraining Flows

    NASA Astrophysics Data System (ADS)

    Prosperetti, Andrea

    2001-11-01

    Air entraining flows are frequently encountered in Nature (e.g. breaking waves, waterfalls, rain over water bodies) and in technological applications (gas-liquid chemical reactors, water treatment, aquaculture, and others). Superficially, one may distinguish between transient events, such as a breaking wave, and steady situations, e.g. a falling jet. However, when viscosity is not important, the process of air entrainment turns out to be the consequence of local transient events even in steady flows. For example, surface disturbances convected by a nominally steady jet impact the receiving liquid, create a deep depression, which collapses entraining an air pocket. (In practice this basic mechanism is complicated by the presence of waves, vortical flows, and other factors.) This talk will describe several examples of air-entraining flows illustrating the fluid mechanic principles involved with high-speed movies and numerical computations.

  8. Air Pollution and Industry.

    ERIC Educational Resources Information Center

    Ross, R. D., Ed.

    This book is an authoritative reference and practical guide designed to help the plant engineer identify and solve industrial air pollution problems in order to be able to meet current air pollution regulations. Prepared under the editorial supervision of an experienced chemical engineer, with each chapter contributed by an expert in his field,…

  9. Portable oven air circulator

    DOEpatents

    Jorgensen, Jorgen A.; Nygren, Donald W.

    1983-01-01

    A portable air circulating apparatus for use in cooking ovens which is used to create air currents in the oven which transfer heat to cooking foodstuffs to promote more rapid and more uniform cooking or baking, the apparatus including a motor, fan blade and housing of metallic materials selected from a class of heat resistant materials.

  10. Embodied linearity of speed control in Drosophila melanogaster

    PubMed Central

    Medici, V.; Fry, S. N.

    2012-01-01

    Fruitflies regulate flight speed by adjusting their body angle. To understand how low-level posture control serves an overall linear visual speed control strategy, we visually induced free-flight acceleration responses in a wind tunnel and measured the body kinematics using high-speed videography. Subsequently, we reverse engineered the transfer function mapping body pitch angle onto flight speed. A linear model is able to reproduce the behavioural data with good accuracy. Our results show that linearity in speed control is realized already at the level of body posture-mediated speed control and is therefore embodied at the level of the complex aerodynamic mechanisms of body and wings. Together with previous results, this study reveals the existence of a linear hierarchical control strategy, which can provide relevant control principles for biomimetic implementations, such as autonomous flying micro air vehicles. PMID:22933185

  11. Embodied linearity of speed control in Drosophila melanogaster.

    PubMed

    Medici, V; Fry, S N

    2012-12-01

    Fruitflies regulate flight speed by adjusting their body angle. To understand how low-level posture control serves an overall linear visual speed control strategy, we visually induced free-flight acceleration responses in a wind tunnel and measured the body kinematics using high-speed videography. Subsequently, we reverse engineered the transfer function mapping body pitch angle onto flight speed. A linear model is able to reproduce the behavioural data with good accuracy. Our results show that linearity in speed control is realized already at the level of body posture-mediated speed control and is therefore embodied at the level of the complex aerodynamic mechanisms of body and wings. Together with previous results, this study reveals the existence of a linear hierarchical control strategy, which can provide relevant control principles for biomimetic implementations, such as autonomous flying micro air vehicles. PMID:22933185

  12. Embodied linearity of speed control in Drosophila melanogaster.

    PubMed

    Medici, V; Fry, S N

    2012-12-01

    Fruitflies regulate flight speed by adjusting their body angle. To understand how low-level posture control serves an overall linear visual speed control strategy, we visually induced free-flight acceleration responses in a wind tunnel and measured the body kinematics using high-speed videography. Subsequently, we reverse engineered the transfer function mapping body pitch angle onto flight speed. A linear model is able to reproduce the behavioural data with good accuracy. Our results show that linearity in speed control is realized already at the level of body posture-mediated speed control and is therefore embodied at the level of the complex aerodynamic mechanisms of body and wings. Together with previous results, this study reveals the existence of a linear hierarchical control strategy, which can provide relevant control principles for biomimetic implementations, such as autonomous flying micro air vehicles.

  13. Apparatus and method for controlling the rotary airlocks in a coal processing system by reversing the motor current rotating the air lock

    SciTech Connect

    Groombridge, C.E.

    1996-11-19

    An improvement is described to a coal processing system where hard materials found in the coal may cause jamming of either inflow or outflow rotary airlocks, each driven by a reversible motor. The instantaneous current used by the motor is continually monitored and compared to a predetermined value. If an overcurrent condition occurs, indicating a jamming of the airlock, a controller means starts a ``soft`` reverse rotation of the motor thereby clearing the jamming. Three patterns of the motor reversal are provided. 10 figs.

  14. Present and Future of Semiconductor Pulsed Power Generator ˜Role of Power Semiconductor Devices in Plasma Research˜ 6.High-Speed, Large-Current Power Semiconductors for Pulse Power Generation

    NASA Astrophysics Data System (ADS)

    Takata, Ikunori

    This paper describes the operation principles and limits of power semiconductors. In addition, operation mechanisms of the new pulse power devices, SOS (Semiconductor Opening Switch) and dynistors, are explained qualitatively. The fastest operating power device is the series connection of comparatively low-voltage devices. For large-current operation, a uniformly operating pin-diode structure device is essential. An SOS is constructed from dozens of medium voltage (about 3kV) special hard-recovery diodes. This can shut off 2kA current at 10kV with in 10ns. The dynistor has n+pnp+ four layers and two electrodes. Serial-connected dynistors have the potential to replace thyratrons. These new devices can endure over 10 kA/cm2 at much higher voltage than their static breakdown values in the repetitive use more than 1011 times.

  15. Generalized Charts for Determination of Pressure Drop of a High-speed Compressible Fluid in Heat-exchanger Passages I : Air Heated in Smooth Passages of Constant Area with Constant Wall Temperature

    NASA Technical Reports Server (NTRS)

    Valerino, Michael F

    1948-01-01

    In the present paper an analysis is made of the compressible-flow variations occurring in heat-exchanger passages. The results of the analysis describe the flow and heating characteristics for which specific flow passages can be treated as segments of generalized flow systems. The graphical representation of the flow variations in the generalized flow systems can then be utilized as working charts to determine directly the pressure changes occurring in any specific flow passage. On the basis of these results, working charts are constructed to handle the case of air heated at constant wall temperature under turbulent-flow conditions. A method is given of incorporating the effect on the heat-exchanger flow process of high temperature differential between passage wall and fluid as based on recent NACA experimental data. Good agreement is obtained between the experimental and the chart pressure-drop values for passage-wall average temperatures as high as 1752 degrees R (experimental limit) and for flow Mach numbers ranging from 0.32 to 1.00 (choke) at the passage exit.

  16. Air Abrasion

    MedlinePlus

    ... delivered directly to your desktop! more... What Is Air Abrasion? Article Chapters What Is Air Abrasion? What Happens? The Pros and Cons Will I Feel Anything? Is Air Abrasion for Everyone? print full article print this ...

  17. Space Derived Air Monitor

    NASA Technical Reports Server (NTRS)

    1983-01-01

    COPAMS, Commonwealth of Pennsylvania Air Monitoring System, derives from technology involved in building unmanned spacecraft. The Nimbus spacecraft carried experimental sensors to measure temperature, pressure, ozone, and water vapor, and instruments for studying solar radiation and telemetry. The process which relayed these findings to Earth formed the basis for COPAMS. The COPAMS system consists of data acquisition units which measure and record pollution level, and sense wind speed and direction, etc. The findings are relayed to a central station where the information is computerized. The system is automatic and supplemented by PAQSS, PA Air Quality Surveillance System.

  18. Air bearing vacuum seal assembly

    DOEpatents

    Booth, Rex

    1978-01-01

    An air bearing vacuum seal assembly capable of rotating at the speed of several thousand revolutions per minute using an air cushion to prevent the rotating and stationary parts from touching, and a two stage differential pumping arrangement to maintain the pressure gradient between the air cushion and the vacuum so that the leak rate into the vacuum is, for example, less than 1 .times. 10.sup.-4 Pa m.sup.3 /s. The air bearing vacuum seal has particular application for mounting rotating targets to an evacuated accelerator beam tube for bombardment of the targets with high-power charged particle beams in vacuum.

  19. High speed door assembly

    DOEpatents

    Shapiro, Carolyn

    1993-01-01

    A high speed door assembly, comprising an actuator cylinder and piston rods, a pressure supply cylinder and fittings, an electrically detonated explosive bolt, a honeycomb structured door, a honeycomb structured decelerator, and a structural steel frame encasing the assembly to close over a 3 foot diameter opening within 50 milliseconds of actuation, to contain hazardous materials and vapors within a test fixture.

  20. High speed door assembly

    DOEpatents

    Shapiro, C.

    1993-04-27

    A high speed door assembly is described, comprising an actuator cylinder and piston rods, a pressure supply cylinder and fittings, an electrically detonated explosive bolt, a honeycomb structured door, a honeycomb structured decelerator, and a structural steel frame encasing the assembly to close over a 3 foot diameter opening within 50 milliseconds of actuation, to contain hazardous materials and vapors within a test fixture.