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Sample records for air layer sal

  1. An Experiment to Study Sporadic Atom Layers in the Earth's Mesosphere and Lower Thermosphere (SAL)

    NASA Technical Reports Server (NTRS)

    Kelley, Michael C.

    1999-01-01

    The Sudden Atom Layer (SAL) Rocket was successfully launched in February 1998. All instruments worked well except those supplied by NASA Goddard Space Flight Center. (A dummy weight was launched for the neutral mass spectrometer and the ion version died shortly after lift-off.) A paper has already been published in GRL concerning the dust layer detected by an on board instrument and compared to ground-based observations made at the Arecibo Observatory by Cornell graduate student S. Collins (lidar) and Q. Zhou (radar). Collins presented a comparison of the sodium lidar data and onboard observations with a theoretical model by Plane and Cox at the Fan AGU Meeting. In addition Gelinas and Kelley presented a review paper dealing with the entire SAL instrument complement at the same meeting. An unexpected new explanation for the outer scale of E region plasma irregularities has come out of the data set. We anticipate at least a total of four papers will be published within a year of launch.

  2. LASE Observations of Saharan Air Layer and African Easterly Waves During NAMMA

    NASA Astrophysics Data System (ADS)

    Ismail, S.; Ferrare, R. A.; Browell, E. V.; Kooi, S.; Dunion, J.; Heymsfield, G. M.; Notari, A.; Butler, C. F.; Burton, S. P.; Fenn, M. A.; Krishnamurti, T. N.; Biswas, M.; Chen, G.; Anderson, B.

    2009-12-01

    The Lidar Atmospheric Sensing Experiment (LASE) on the NASA DC-8 aircraft provided the first simultaneous measurements of water vapor and aerosol distributions to study the thermodynamic characteristics of the Saharan Air Layer (SAL) and its impact on African Easterly Waves (AEWs) during the NASA African Monsoon Multidisciplinary Analyses (NAMMA) campaign. LASE data were used to derive profiles of aerosol scattering ratios, aerosol extinction coefficients, aerosol optical thickness, water vapor mixing ratios, and relative humidity (RH). LASE measurements and temperature profiles from the GPS dropsondes were used to characterize the SAL, convection, and clear air regions. Three case studies were selected for detailed analysis: 1) a vertically stratified SAL, with high-resolution layering (unlike a vertically well-mixed SAL), 2) a SAL with high RH, and 3) a SAL surrounded by dry air intrusions. The average extinction-to-backscatter ratios derived from LASE measurements over the dust layers varied from 35±5 to 45±5, which are well within the range of values determined by other lidar systems. LASE aerosol extinction and water vapor profiles were validated by comparison with onboard in situ aerosol measurements and dropsonde water vapor soundings, respectively. An analysis of LASE data suggests that the SAL suppresses low-altitude convection. A summary of latitudinal and longitudinal distributions of aerosol and water vapor distribution in SAL and non-SAL events is also presented.

  3. Re-Evaluating the Role of the Saharan Air Layer in Atlantic Tropical Cyclogenesis and Evolution

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.

    2010-01-01

    The existence of the Saharan air layer (SAL), a layer of warm, dry, dusty air frequently present over the tropical Atlantic Ocean, has long been appreciated. The nature of its impact on hurricanes remains unclear, however, with some researchers arguing that the SAL amplifies hurricane development and with others arguing that it inhibits it. Most research in recent years has emphasized the potential negative impacts of the SAL, but is this emphasis justified? The potential negative impacts of the SAL include 1) vertical wind shear associated with the African easterly jet; 2) warm air aloft, which increases thermodynamic stability at the base of the SAL; and 3) dry air, which produces cold downdrafts. Multiple NASA satellite data sets and NCEP global analyses are used to characterize the SAL's properties and evolution in relation to tropical cyclones and to evaluate these potential negative influences. The results suggest that the negative influences of the SAL have been significantly over-emphasized, in part because of several false assumptions about the structure and role of the SAL.

  4. Improving Our Understanding of Atlantic Hurricanes Through Knowledge of the Saharan Air Layer: Hope Or Hype?

    NASA Technical Reports Server (NTRS)

    Braun, Scott

    2009-01-01

    The existence of the Saharan air layer (SAL), a layer of warm, dry, dusty air frequently present over the tropical Atlantic Ocean, has long been appreciated. The nature of its impact on hurricanes remains unclear, with some researchers arguing that the SAL amplifies hurricane development and with others arguing that it inhibits it. The potential negative impacts of the SAL include 1) low-level vertical wind shear associated with the African easterly jet; 2) warm air aloft, which increases thermodynamic stability; and 3) dry air, which produces cold downdrafts. Some investigators have assumed the validity of these proposed negative influences and have frequently used them to explain the failure of individual storms to intensify or to explain the relative inactivity of recent hurricane seasons. Multiple NASA satellite data sets and National Centers for Environmental Prediction global analyses are used to characterize the SAL's properties and evolution in relation to developing hurricanes. The results will shows that neither jet--induced vertical wind shear nor warm SAL air (high stability) produce significant negative impacts on Atlantic storms. Dry air appears to be a key mechanism for SAL influence, but the presence of dry SAL air is not always a good indicator of whether a storm will weaken since many examples of intensifying storms surrounded by such dry air can be found. Idealized simulations will be used to evaluate the role of dry air. Finally, two case studies of supposedly "prime examples" of SAL influence will show that the negative influences of the SAL are perhaps too readily ascribed to individual storms that fail to reach their maximum potential intensity.

  5. The Impact of Saharan Air Layer Dust on the Intensity and Intensity Change of Hurricane Earl

    NASA Astrophysics Data System (ADS)

    Bucher, G.; Boybeyi, Z.

    2012-12-01

    The study of tropical cyclone (TC) intensity and intensity change has become an increasingly important research topic, as the storms pose a significant threat to the lives and property along coastal regions, and maritime interests. The Saharan Air Layer (SAL) is an elevated layer of warm, dry, and dusty air that is formed by intense heating and strong winds over the Sahara desert. This dust, and hot and dry air moves across the Atlantic over the maritime layer. An emerging area of research is the role that the SAL has on the development and intensity of TCs in the North Atlantic tropical basin. In 2010, Hurricane Earl gave us a unique opportunity to study the effects of the SAL during the formative stages of the storm. Using the Weather and Forecasting Model with chemistry (WRF-Chem), this study investigated what the effect of SAL characteristics (thermodynamic and aerosol) had on Earl's intensity and intensity change. We concentrated on the direct and indirect radiative effects of the SAL aerosols, by utilizing the dust-only module in WRF-Chem and comparing results to observations, reanalysis, and a dust-free run. The results show that Earl did not appreciably intensify until it moved out from beneath the influence of the SAL, after which it evolved into a CAT 4 hurricane. This was due mainly to the shear associated with the SAL, but the dust radiative effects also contributed to the slow growth.

  6. LASE Observations of Interactions Between African Easterly Waves and the Saharan Air Layer

    NASA Technical Reports Server (NTRS)

    Ismail, Syed; Ferrare, Richard; Browell, Edward; Kooi, Susan; Biswas, Mrinal; Krishnamurti, T. N.; Notari, Anthony; Heymsfield, Andrew; Butler, Carolyn; Burton, Sharon; Fenn, Marta; Dunion, Jason

    2010-01-01

    The Lidar Atmospheric Sensing Experiment (LASE) participated in the NASA African Monsoon Multidisciplinary Analyses (NAMMA) field experiment in 2006 that was conducted from Sal, Cape Verde to study the Saharan Air Layer (SAL) and its influence on the African Easterly Waves (AEWs) and Tropical Cyclones (TCs). During NAMMA, LASE collected simultaneous water vapor and aerosol lidar measurements from 14 flights onboard the NASA DC- 8. In this paper we present three examples of the interaction of the SAL and AEWs regarding: moistening of the SAL and transfer of latent heat; injection of dust in an updraft; and influence of dry air intrusion on an AEW. A brief discussion is also given on activities related to the refurbishment of LASE to enhance its operational performance and plans to participate in the next NASA hurricane field experiment in the summer of 2010.

  7. Influence of the Saharan Air Layer on Atlantic tropical cyclone formation during the period 1-12 September 2003

    NASA Astrophysics Data System (ADS)

    Pan, Weiyu; Wu, Liguang; Shie, Chung-Lin

    2011-01-01

    Atmospheric Infrared Sounder (AIRS) data show that the Saharan air layer (SAL) is a dry, warm, and well-mixed layer between 950 and 500 hPa over the tropical Atlantic, extending westward from the African coast to the Caribbean Sea. The formations of both Hurricane Isabel and Tropical Depression 14 (TD14) were accompanied with outbreaks of SAL air during the period 1-12 September 2003, although TD14 failed to develop into a named tropical cyclone. The influence of the SAL on their formations is investigated by examining data from satellite observations and numerical simulations, in which AIRS data are incorporated into the MM5 model through the nudging technique. Analyses of the AIRS and simulation data suggest that the SAL may have played two roles in the formation of tropical cyclones during the period 1-12 September 2003. First, the outbreaks of SAL air on 3 and 8 September enhanced the transverse-vertical circulation with the rising motion along the southern edge of the SAL and the sinking motion inside the SAL, triggering the development of two tropical disturbances associated with Hurricane Isabel and TD14. Second, in addition to the reduced environmental humidity and enhanced static stability in the lower troposphere, the SAL dry air intruded into the inner region of these tropical disturbances as their cyclonic flows became strong. This effect may have slowed down the formation of Isabel and inhibited TD14 becoming a named tropical cyclone, while the enhanced vertical shear contributed little to tropical cyclone formation during this period. The 48-h trajectory calculations confirm that the parcels from the SAL can be transported into the inner region of an incipient tropical cyclone.

  8. Reevaluating the Role of Saharan Air Layer in Atlantic Tropical Cyclogenesis and Evolution

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.

    2010-01-01

    The existence of the Saharan air layer (SAL), a layer of warm, dry, dusty air that frequently moves westward off of the Saharan desert of Africa and over the tropical Atlantic Ocean, has long been appreciated. As air moves over the desert, it is strongly heated from below, producing a very hot air mass at low levels. Because there is no moisture source over the Sahara, the rise in temperature causes a sharp drop in relative humidity, thus drying the air. In addition, the warm air produces a very strong jet of easterly flow in the middle troposphere called the African easterly jet that is thought to play a critical role in hurricane formation. In recent years, there has been an increased focus on the impact that the SAL has on the formation and evolution of hurricanes in the Atlantic. However, the nature of its impact remains unclear, with some researchers arguing that the SAL amplifies hurricane development and with others arguing that it inhibits it. The argument for positively influencing hurricane development is based upon the fact that the African easterly jet provides an energy source for the waves that eventually form hurricanes and that it leads to rising motion south of the jet that favors the development of deep thunderstorm clouds. The potential negative impacts of the SAL include 1) low-level vertical wind shear associated with the African easterly jet; 2) warm SAL air aloft, which increases thermodynamic stability and suppresses cloud development; and 3) dry air, which produces cold downdrafts in precipitating regions, thereby removing energy needed for storm development. As part of this recent focus on the SAL and hurricanes (which motivated a 2006 NASA field experiment), there has been little emphasis on the SAL s potential positive influences and almost complete emphasis on its possible negative influences, almost to the point of claims that the SAL is the major suppressing influence on hurricanes in the Atlantic. In this study, multiple NASA

  9. LASE Measurements of Water Vapor, Aerosol, and Cloud Distributions in Saharan Air Layers and Tropical Disturbances

    NASA Technical Reports Server (NTRS)

    Ismail, Syed; Ferrare, Richard A.; Browell, Edward V.; Kooi, Susan A.; Dunion, Jason P.; Heymsfield, Gerry; Notari, Anthony; Butler, Carolyn F.; Burton, Sharon; Fenn, Marta; Krishnamurti, T. N.; Chen, Gao; Anderson, Bruce

    2010-01-01

    LASE (Lidar Atmospheric Sensing Experiment) on-board the NASA DC-8 measured high resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern North Atlantic during the NAMMA (NASA African Monsoon Multidisciplinary Analyses) field experiment. These measurements were used to study African easterly waves (AEWs), tropical cyclones (TCs), and the Saharan Air Layer(s) (SAL). Interactions between the SAL and tropical air were observed during the early stages of the TC development. These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its impact on AEWs and TCs. Examples of profile measurements of aerosol scattering ratios, aerosol extinction coefficients, aerosol optical thickness, water vapor mixing ratios, RH, and temperature are presented to illustrate their characteristics in SAL, convection, and clear air regions. LASE data suggest that the SAL suppresses low-altitude convection at the convection-SAL interface region. Mid-level convection associated with the AEW and transport are likely responsible for high water vapor content observed in the southern regions of the SAL on August 20, 2008. This interaction is responsible for the transfer of about 7 x 10(exp 15) J latent heat energy within a day to the SAL. Measurements of lidar extinction-to-backscatter ratios in the range 36+/-5 to 45+/-5 are within the range of measurements from other lidar measurements of dust. LASE aerosol extinction and water vapor profiles are validated by comparison with onboard in situ aerosol measurements and GPS dropsonde water vapor soundings, respectively.

  10. The seasonal vertical distribution of the Saharan Air Layer and its modulation by the wind

    NASA Astrophysics Data System (ADS)

    Tsamalis, C.; Chédin, A.; Pelon, J.; Capelle, V.

    2013-11-01

    The Saharan Air Layer (SAL) influences large-scale environment from western Africa to eastern tropical Americas, by carrying large amounts of dust aerosols. However, the vertical distribution of the SAL is not well established due to a lack of systematic measurements away from the continents. This can be overcome by using the observations of the spaceborne lidar CALIOP onboard the satellite CALIPSO. By taking advantage of CALIOP's capability to distinguish dust aerosols from other types of aerosols through depolarization, the seasonal vertical distribution of the SAL is analyzed at 1° horizontal resolution over a period of 5 yr (June 2006-May 2011). This study shows that SAL can be identified all year round displaying a clear seasonal cycle. It occurs higher in altitude and more northern in latitude during summer than during winter, but with similar latitudinal extent near Africa for the four seasons. The south border of the SAL is determined by the Intertropical Convergence Zone (ITCZ), which either prohibits dust layers from penetrating it or reduces significantly the number of dust layers seen within or south of it, as over the eastern tropical Atlantic. Spatially, near Africa, it is found between 5° S and 15° N in winter and 5-30° N in summer. Towards the Americas (50° W), SAL is observed between 5° S and 10° N in winter and 10-25° N in summer. During spring and fall, SAL is found between the position of winter and summer not only spatially but also vertically. In winter, SAL occurs in the altitude range 0-3 km off western Africa, decreasing to 0-2 km close to South America. During summer, SAL is found to be thicker and higher near Africa at 1-5 km, reducing to 0-2 km in the Gulf of Mexico, farther west than during the other seasons. SAL is confined to one layer, of which the mean altitude decreases with westward transport by 13 m deg-1 during winter and 28 m deg-1, after 30° W, during summer. Its mean geometrical thickness decreases by 25 m deg-1 in

  11. Vertical distribution of the Saharan Air Layer from 5 years of CALIPSO observations

    NASA Astrophysics Data System (ADS)

    Tsamalis, C.; Chédin, A.

    2012-04-01

    The Saharan Air Layer (SAL) forms as dry and hot air moves across the Sahara desert. SAL, containing substantial amounts of mineral dust, is a dominant feature that influences the large scale environment from West Africa to eastern tropical America, inhibiting tropical cyclogenesis and Atlantic hurricane formation. Furthermore, SAL dust aerosols have a strong impact on the energy budget through the so-called direct and indirect effects. The SAL has been studied with dedicated campaigns at the two sides of the Atlantic or using space observations due to lack of systematic in situ measurements away from the continents. However the campaigns are restricted in time, while satellite observations of thermodynamic variables are affected by the presence of dust. Moreover, satellite measurements of aerosols, particularly in the visible, mostly provide column integrated properties like the optical depth, without information about the vertical distribution. On the other hand, new generation infrared sounders now bring reliable information on the dust layer mean altitude, but their new established results need further validation. However, the two-wavelength lidar CALIOP, launched on board CALIPSO in April 2006, permits an accurate determination of the aerosol vertical distribution, on a global scale. Thanks to depolarisation at 532 nm, CALIOP is able to discriminate between dust and other types of aerosols, which generally do not depolarize light. Here, the L2 5 km aerosol layer product (version 3.01) is used to calculate the vertical distribution of the dust aerosols above the Atlantic during the last 5 years (June 2006 - May 2011) with a horizontal resolution of 1 degree for the four seasons. More specifically, two classes of aerosols are used from the L2 product: dust and polluted dust, in order to take into account the change of dust aerosols optical properties with transport. Results show the latitudinal displacement of the SAL between winter [-5, 15]°N and summer [10

  12. Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Rodríguez, S.; Alastuey, A.; Alonso-Pérez, S.; Querol, X.; Cuevas, E.; Abreu-Afonso, J.; Viana, M.; Pérez, N.; Pandolfi, M.; de La Rosa, J.

    2011-07-01

    An analysis of chemical composition data of particulate matter samples (TSP, PM10 and PM2.5) collected from 2002 to 2008 in the North Atlantic free troposphere at the Izaña Global Atmospheric Watch (GAW) observatory (Tenerife, Canary Islands) shows that desert dust is very frequently mixed with particulate pollutants in the Saharan Air Layer (SAL). The study of this data set with Median Concentrations At Receptor (MCAR) plots allowed the identification of the potential source regions of the dust and particulate pollutants. Areas located at the south of the southern slope of the Atlas mountains emerge as the most frequent source of the soil desert dust advected to the northern edge of the SAL in summer. Industrial emissions occurring in Northern Algeria, Eastern Algeria, Tunisia and the Atlantic coast of Morocco appear as the most important source of the nitrate, ammonium and a fraction of sulphate (at least 60 % of the sulphate <10 μm transported from some regions) observed in the SAL. These emissions are mostly linked to crude oil refineries, phosphate-based fertilizer industry and power plants. Although desert dust emissions appear as the most frequent source of the phosphorous observed in the SAL, high P concentrations are observed when the SAL is affected by emissions from open mines of phosphate and phosphate based fertilizer industry. The results also show that a significant fraction of the sulphate (up to 90 % of sulphate <10 μm transported from some regions) observed in the SAL may be influenced by soil emissions of evaporite minerals in well defined regions where dry saline lakes (chotts) are present. These interpretations of the MCAR plots are consistent with the results obtained with the Positive Matrix Factorization (PMF2) receptor modelling. The results of this study show that North African industrial pollutants may be mixed with desert dust and exported to the North Atlantic in the Saharan Air Layer.

  13. Transport of desert dust mixed with North African industrial pollutants in the subtropical Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Rodríguez, S.; Alastuey, A.; Alonso-Pérez, S.; Querol, X.; Cuevas, E.; Abreu-Afonso, J.; Viana, M.; Pandolfi, M.; de La Rosa, J.

    2011-03-01

    The chemical composition of particulate matter samples (TSP, PM10 and PM2.5) collected from 2002 to 2008 in the North Atlantic free troposphere at Izaña Global Atmospheric Watch (GAW) observatory (Tenerife, The Canary Islands) was studied. The analysis of the samples collected in the Saharan Air Layer (SAL) shows that soil desert dust is very frequently mixed with particulate pollutants. An analysis of this data set with Median Concentrations At Receptor (MCAR) plots allowed to identify the potential source regions of the dust and particulate pollutants. Areas located at the south of the Southern slope of Atlas emerge as the most frequent source of the soil desert dust advected to the northern edge of the SAL in summer. Industrial emissions occurring along the Atlantic coast of Morocco, Northern Algeria, Eastern Algeria and Tunisia appear as the most important source of the nitrate, ammonium and a fraction of sulphate (at least a 60% of the sulphate <10 μm transported from some regions) observed in the SAL. These emissions are mostly linked to crude oil refineries, phosphate-based fertilizer industry and power plants. Although desert dust emissions appear as the most frequent source of the phosphorous observed in the SAL, high P concentrations are observed when the SAL is affected by emissions from open mines of phosphate and phosphate based fertilizer industry. The results also show that a significant fraction of the sulphate (up to 90% of sulphate <10 μm transported from some regions) observed in the SAL is linked to soil emissions of evaporite minerals in well defined regions where dry saline lakes (chotts) are present. These interpretations of the MCAR plots are consistent with the results obtained with the Positive Matrix Factorization receptor modelling. The results of this study show that North African industrial pollutants may be mixed with desert dust and exported to the North Atlantic in the Saharan Air Layer.

  14. LASE Measurements of Water Vapor, Aerosol, and Cloud Distributions in Saharan Air Layers and Tropical Disturbances

    NASA Technical Reports Server (NTRS)

    Ismail, Syed; Ferrare, Richard; Browell, Edward; Kooi, Susan; Notari, Anthony; Butler, Carolyn; Burton, Sharon; Fenn, Marta; Krishnamurti, T. N.; Dunion, Jason; Heymsfield, Gerry; Anderson, Bruce

    2008-01-01

    LASE (Lidar Atmospheric Sensing Experiment) onboard the NASA DC-8 was used to measure high resolution profiles of water vapor and aerosols, and cloud distributions in 14 flights over the eastern Atlantic region during the NAMMA (NASA African Monsoon Multidisciplinary Analyses) field experiment, which was conducted from August 15 to September 12, 2006. These measurements were made in conjunction with flights designed to study African Easterly Waves (AEW), Tropical Disturbances (TD), and Saharan Aerosol Layers (SALs) as well as flights performed in clear air and convective regions. As a consequence of their unique radiative properties and dynamics, SAL layers have a significant influence in the development of organized convection associated with TD. Interactions of the SAL with tropical air during early stages of the development of TD were observed. These LASE measurements represent the first simultaneous water vapor and aerosol lidar measurements to study the SAL and its impact on TDs and hurricanes. Seven AEWs were studied and four of these evolved into tropical storms and three did not. Three out of the four tropical storms evolved into hurricanes.

  15. Improving our Understanding of Atlantic Tropical Cyclones through Knowledge of the Saharan Air Layer: Hope or Hype?

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.; Shie, Chung-Lin

    2008-01-01

    The existence of the Saharan air layer (SAL), a layer of warm, dry, dusty air that frequently moves westward off of the Saharan desert of Africa and over the tropical Atlantic Ocean, has long been appreciated. As air moves over the desert, it is strongly heated from below, producing a very hot air mass at low levels. Because there is no moisture source over the Sahara, the rise in temperature causes a sharp drop in relative humidity, thus drying the air. In addition, the warm air produces a very strong jet of easterly flow in the middle troposphere called the African easterly jet that is thought to play a critical role in hurricane formation. In recent years, there has been an increased focus on the impact that the SAL has on the formation and evolution of hurricanes in the Atlantic. However, the nature of its impact remains unclear, with some researchers arguing that the SAL amplifies hurricane development and with others arguing that it inhibits it. The argument for positively influencing hurricane development is based upon the fact that the African easterly jet produces the waves that eventually form hurricanes and that it leads to rising motion south of the jet that favors the development of deep thunderstorm clouds. The potential negative impacts of the SAL include 1) low-level vertical wind shear associated with the African easterly jet; 2) warm SAL air aloft, which increases thermodynamic stability and suppresses cloud development; and 3) dry air, which produces cold downdrafts in precipitating regions, thereby removing energy needed for storm development. As part of this recent focus on the SAL and hurricanes (which motivated a 2006 NASA field experiment), there has been little emphasis on the SAL s potential positive influences and almost complete emphasis on its possible negative influences, almost to the point of claims that the SAL is the major suppressing influence on hurricanes in the Atlantic. Multiple NASA satellite data sets (TRMM, MODIS, and AIRS

  16. Ice nucleating particles in the Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Boose, Yvonne; Sierau, Berko; García, M. Isabel; Rodríguez, Sergio; Alastuey, Andrés; Linke, Claudia; Schnaiter, Martin; Kupiszewski, Piotr; Kanji, Zamin A.; Lohmann, Ulrike

    2016-07-01

    This study aims at quantifying the ice nucleation properties of desert dust in the Saharan Air Layer (SAL), the warm, dry and dust-laden layer that expands from North Africa to the Americas. By measuring close to the dust's emission source, before aging processes during the transatlantic advection potentially modify the dust properties, the study fills a gap between in situ measurements of dust ice nucleating particles (INPs) far away from the Sahara and laboratory studies of ground-collected soil. Two months of online INP concentration measurements are presented, which were part of the two CALIMA campaigns at the Izaña observatory in Tenerife, Spain (2373 m a.s.l.), in the summers of 2013 and 2014. INP concentrations were measured in the deposition and condensation mode at temperatures between 233 and 253 K with the Portable Ice Nucleation Chamber (PINC). Additional aerosol information such as bulk chemical composition, concentration of fluorescent biological particles as well as the particle size distribution was used to investigate observed variations in the INP concentration. The concentration of INPs was found to range between 0.2 std L-1 in the deposition mode and up to 2500 std L-1 in the condensation mode at 240 K. It correlates well with the abundance of aluminum, iron, magnesium and manganese (R: 0.43-0.67) and less with that of calcium, sodium or carbonate. These observations are consistent with earlier results from laboratory studies which showed a higher ice nucleation efficiency of certain feldspar and clay minerals compared to other types of mineral dust. We find that an increase of ammonium sulfate, linked to anthropogenic emissions in upwind distant anthropogenic sources, mixed with the desert dust has a small positive effect on the condensation mode INP per dust mass ratio but no effect on the deposition mode INP. Furthermore, the relative abundance of biological particles was found to be significantly higher in INPs compared to the ambient

  17. The Evolution and Role of the Saharan Air Layer During Hurricane Helene (2006)

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.; Sippel, Jason A.; Shie, Chung-Lin; Boller, Ryan A.

    2013-01-01

    The Saharan air layer (SAL) has received considerable attention in recent years as a potential negative influence on the formation and development of Atlantic tropical cyclones. Observations of substantial Saharan dust in the near environment of Hurricane Helene (2006) during the National Aeronautics and Space Administration (NASA) African Monsoon Multidisciplinary Activities (AMMA) Experiment (NAMMA) field campaign led to suggestions about the suppressing influence of the SAL in this case. In this study, a suite of satellite remote sensing data, global meteorological analyses, and airborne data are used to characterize the evolution of the SAL in the environment of Helene and assess its possible impact on the intensity of the storm. The influence of the SAL on Helene appears to be limited to the earliest stages of development, although the magnitude of that impact is difficult to determine observationally. Saharan dust was observed on the periphery of the storm during the first two days of development after genesis when intensification was slow. Much of the dust was observed to move well westward of the storm thereafter, with little SAL air present during the remainder of the storm's lifetime and with the storm gradually becoming a category-3 strength storm four days later. Dry air observed to wrap around the periphery of Helene was diagnosed to be primarily non-Saharan in origin (the result of subsidence) and appeared to have little impact on storm intensity. The eventual weakening of the storm is suggested to result from an eyewall replacement cycle and substantial reduction of the sea surface temperatures beneath the hurricane as its forward motion decreased.

  18. Principle Component Analysis of the Evolution of the Saharan Air Layer and Dust Transport: Comparisons between a Model Simulation and MODIS Retrievals

    NASA Technical Reports Server (NTRS)

    Wong, S.; Colarco, P. R.; Dessler, A.

    2006-01-01

    The onset and evolution of Saharan Air Layer (SAL) episodes during June-September 2002 are diagnosed by applying principal component analysis to the NCEP reanalysis temperature anomalies at 850 hPa, where the largest SAL-induced temperature anomalies are located. The first principal component (PC) represents the onset of SAL episodes, which are associated with large warm anomalies located at the west coast of Africa. The second PC represents two opposite phases of the evolution of the SAL. The positive phase of the second PC corresponds to the southwestward extension of the warm anomalies into the tropical-subtropical North Atlantic Ocean, and the negative phase corresponds to the northwestward extension into the subtropical to mid-latitude North Atlantic Ocean and the southwest Europe. A dust transport model (CARMA) and the MODIS retrievals are used to study the associated effects on dust distribution and deposition. The positive (negative) phase of the second PC corresponds to a strengthening (weakening) of the offshore flows in the lower troposphere around 10deg - 20degN, causing more (less) dust being transported along the tropical to subtropical North Atlantic Ocean. The variation of the offshore flow indicates that the subseasonal variation of African Easterly Jet is associated with the evolution of the SAL. Significant correlation is found between the second PC time series and the daily West African monsoon index, implying a dynamical linkage between West African monsoon and the evolution of the SAL and Saharan dust transport.

  19. Soluble iron dust export in the high altitude Saharan Air Layer

    NASA Astrophysics Data System (ADS)

    Ravelo-Pérez, L. M.; Rodríguez, S.; Galindo, L.; García, M. I.; Alastuey, A.; López-Solano, J.

    2016-05-01

    Every summer huge amounts of desert dust particles are exported from the hyperarid subtropical Sahara to the North Atlantic the so-called Saharan Air Layer (SAL), a dry, warm and dust-laden corridor that expands from the North African coast (1-5 km.a.s.l.) to the Americas above the marine boundary layer. Because of the potential impact of the dust deposited on the ocean on marine biogeochemistry and climate, we studied the Fe solubility (in seawater) of atmospheric aerosols samples directly collected in the SAL off the North African coast, i.e. the fresh aerosols recently exported from the Sahara in the SAL. The aerosol sampling was performed at ∼2400 m.a.s.l. in Izaña observatory in Tenerife island. In the total aerosols, we found low Fe concentrations and high fractional Fe solubility (FFS ∼2%) in the North Atlantic free troposphere airflows and high Fe concentrations and low FFS (∼0.7%) within the SAL; the resulting FFS versus total dust (or total Fe) plot shows a hyperbolic trend attributed to the conservative mixing of 'fine combustion aerosols' and 'lithogenic mineral dust'. We then focused on the soluble Fe in the SAL. Our results indicate that ∼70% of soluble Fe is associated with the dissolution of submicron dust particles, probably involving Fe-bearing clays. We found a FFS of submicron dust (∼6%) higher than that typically observed in submicron particles of soil dust samples (<1%). The correlation between FFS and the ammonium-sulphate/dust ratio and the low variability in the Fe/Al ratio in the dust samples, suggests that the increase in the FFS of submicron dust aerosols (with respect to soil dust particles) may be related to the presence of acid pollutants mixed with dust. Previous studies had focused on dust processing and changes of Fe solubility during the trans-Atlantic transport of dust in the SAL. We found that submicron dust exported off the coast of North Africa may have already experienced acid processing over the Sahara, i

  20. An Overview of SAL

    NASA Technical Reports Server (NTRS)

    Bensalem, Saddek; Ganesh, Vijay; Lakhnech, Yassine; Munoz, Cesar; Owre, Sam; Ruess, Harald; Rushby, John; Rusu, Vlad; Saiedi, Hassen; Shankar, N.

    2000-01-01

    To become practical for assurance, automated formal methods must be made more scalable, automatic, and cost-effective. Such an increase in scope, scale, automation, and utility can be derived from an emphasis on a systematic separation of concerns during verification. SAL (Symbolic Analysis Laboratory) attempts to address these issues. It is a framework for combining different tools to calculate properties of concurrent systems. The heart of SAL is a language, developed in collaboration with Stanford, Berkeley, and Verimag for specifying concurrent systems in a compositional way. Our instantiation of the SAL framework augments PVS with tools for abstraction, invariant generation, program analysis (such as slicing), theorem proving, and model checking to separate concerns as well as calculate properties (i.e., perform, symbolic analysis) of concurrent systems. We. describe the motivation, the language, the tools, their integration in SAL/PAS, and some preliminary experience of their use.

  1. Modification of Saharan air layer and environmental shear over the eastern Atlantic Ocean by dust-radiation effects

    NASA Astrophysics Data System (ADS)

    Chen, Shu-Hua; Wang, Sheng-Hsiang; Waylonis, Mark

    2010-11-01

    This study investigates the influence of dust-radiation effects on the modification of the Saharan air layer (SAL) and environmental shear. A tracer model based on the Weather Research and Forecast model was developed to examine the influence using a dust outbreak event. Two numerical experiments were conducted with (ON) and without (OFF) the dust-radiation effects. Both simulations reasonably reproduced SAL's features. However, the 700 hPa maximum temperature within SAL was slightly underestimated and shifted northwestward from OFF. These were improved from ON, but the maximum temperature became slightly overestimated, which might be due to inaccurate optical properties. The dust-radiation interactions mainly warmed the dusty air between 750 and 550 hPa because dust shortwave absorption dominated dust longwave cooling. Another major warming area was found near the surface over the ocean due to longwave radiative heating by dust aloft. The modification of temperature resulted in an adjustment of the vertical wind shear. To the south of SAL, where easterly wave disturbances and tropical storms usually occur, the vertical zonal wind shear increased by about 1˜2.5 m s-1 km-1 from 750 to 550 hPa, resulting in a maximum wind change of 3˜5 m s-1, a 30˜40% increase, around the top of this layer. The enhancement of the vertical shear in this layer could potentially have an impact on TC genesis and development. The dust-radiation effects also modified the moisture and dust distribution, which can have a feedback (i.e., a secondary effect) on the heating profile and the vertical shear.

  2. Boundary Layers of Air Adjacent to Cylinders

    PubMed Central

    Nobel, Park S.

    1974-01-01

    Using existing heat transfer data, a relatively simple expression was developed for estimating the effective thickness of the boundary layer of air surrounding cylinders. For wind velocities from 10 to 1000 cm/second, the calculated boundary-layer thickness agreed with that determined for water vapor diffusion from a moistened cylindrical surface 2 cm in diameter. It correctly predicted the resistance for water vapor movement across the boundary layers adjacent to the (cylindrical) inflorescence stems of Xanthorrhoea australis R. Br. and Scirpus validus Vahl and the leaves of Allium cepa L. The boundary-layer thickness decreased as the turbulence intensity increased. For a turbulence intensity representative of field conditions (0.5) and for νwindd between 200 and 30,000 cm2/second (where νwind is the mean wind velocity and d is the cylinder diameter), the effective boundary-layer thickness in centimeters was equal to [Formula: see text]. PMID:16658855

  3. A comparative study of the role of the Saharan air layer in the evolution of two disparate Atlantic tropical cyclones using WRF model simulations and energetics calculations

    NASA Astrophysics Data System (ADS)

    Ross, Robert S.; Krishnamurti, T. N.; Chaney, Kirsten M.

    2016-02-01

    The Weather Research and Forecasting (WRF) Model 5-day simulations of Major Hurricane Julia (2010) and Tropical Storm Florence (2012), both of which developed from African easterly waves, are used to conduct a complete energetics study to explain why one storm became a major hurricane while the other weakened to a wave. The disparate intensity outcomes are caused by significant differences in the energetics of the two systems that emerge in their storm stages due to differences in the impact of the Saharan air layer (SAL). In their wave stages both waves exhibit a convectively driven energy production cycle, in which the regions of positive barotropic and baroclinic energy conversion and of diabatic heating and rainfall are all superimposed. Convection induces barotropic instability which then enhances the baroclinic overturning through a resonance of the two instabilities, which together produce the eddy kinetic energy. Diabatic heating in the convection generates eddy available potential energy which, along with the eddy kinetic energy, defines the total eddy energy of the system. Florence loses the convectively driven energy production cycle in the storm stage and begins to weaken, while Julia maintains this cycle and becomes a major hurricane. The disruption of the convection in Florence is due to the drying, stabilizing, and vertical shearing effects of an expansive SAL to the north of the storm, effects not present in the Julia case. Consideration is given to the different effects of the SAL on 6-10 day waves (Florence wave) versus 3-5 day waves (Julia wave).

  4. Leaping shampoo glides on a lubricating air layer

    NASA Astrophysics Data System (ADS)

    Lee, S.; Li, E. Q.; Marston, J. O.; Bonito, A.; Thoroddsen, S. T.

    2013-06-01

    When a stream of shampoo is fed onto a pool in one's hand, a jet can leap sideways or rebound from the liquid surface in an intriguing phenomenon known as the Kaye effect. Earlier studies have debated whether non-Newtonian effects are the underlying cause of this phenomenon, making the jet glide on top of a shear-thinning liquid layer, or whether an entrained air layer is responsible. Herein we show unambiguously that the jet slides on a lubricating air layer. We identify this layer by looking through the pool liquid and observing its rupture into fine bubbles. The resulting microbubble sizes suggest this air layer is of submicron thickness. This thickness estimate is also supported by the tangential deceleration of the jet during the rebounding.

  5. R2 AIRS/AFS PERMITS GIS LAYER

    EPA Science Inventory

    The Region 2 AIRS/AFS Permits Regulated Facility GIS layer contains identification (name, address, ID), and location (latitude, longitude, and locational metadata), attributes of stationary source(s) of air pollution associated with facilities that are regulated by the U. S. EPA....

  6. Evaporation of stationary alcohol layer in minichannel under air flow

    NASA Astrophysics Data System (ADS)

    Afanasyev, Ilya; Orlova, Evgenija; Feoktistov, Dmitriy

    2015-01-01

    This paper presents experimental investigation of effect of the gas flow rate moving parallel to the stationary liquid layer on the evaporation rate under the conditions of formation of a stable plane "liquid-gas" interface. The average evaporation flow rate of liquid layer (ethanol) by the gas flow (air) has been calculated using two independent methods. Obtained results have been compared with previously published data.

  7. Air-mass origin in the tropical lower stratosphere: The influence of Asian boundary layer air

    NASA Astrophysics Data System (ADS)

    Orbe, Clara; Waugh, Darryn W.; Newman, Paul A.

    2015-05-01

    A climatology of air-mass origin in the tropical lower stratosphere is presented for the Goddard Earth Observing System Chemistry Climate Model. During late boreal summer and fall, air-mass fractions reveal that as much as 20% of the air in the tropical lower stratosphere last contacted the planetary boundary layer (PBL) over Asia; by comparison, the air-mass fractions corresponding to last PBL contact over North America and over Europe are negligible. Asian air reaches the extratropical tropopause within a few days of leaving the boundary layer and is quasi-horizontally transported into the tropical lower stratosphere, where it persists until January. The rapid injection of Asian air into the lower stratosphere—and its persistence in the deep tropics through late (boreal) winter—is important as industrial emissions over East Asia continue to increase. Hence, the Asian monsoon may play an increasingly important role in shaping stratospheric composition.

  8. The footprints of Saharan air layer and lightning on the formation of tropical depressions over the eastern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Centeno Delgado, Diana C.; Chiao, Sen

    2014-09-01

    The roles of the Saharan Air Layer (SAL) and lightning during genesis of Tropical Depression (TD) 8 (2006) and TD 12 (2010) were investigated in relation to the interaction of the dust outbreaks with each system and their surrounding environment. This study applied data collected from the 2006 NASA African Monsoon Multidisciplinary Analysis and 2010 Genesis and Rapid Intensification Processes projects. Satellite observations from METEOSAT and Moderate Resolution Imaging Spectroradiometer (MODIS)—Aerosol Optical Depth (AOD) were also employed for the study of the dust content. Lightning activity data from the Met Office Arrival Time Difference (ATD) system were used as another parameter to correlate moist convective overturning and a sign of cyclone formation. The AOD and lightning analysis for TD 8 demonstrated the time-lag connection through their positive contribution to TC-genesis. TD 12 developed without strong dust outbreak, but with lower wind shear (2 m s-1) and an organized Mesoscale Convective System (MCS). Overall, the results from the combination of various data analyses in this study support the fact that both systems developed under either strong or weak dust conditions. From these two cases, the location (i.e., the target area) of strong versus weak dust outbreaks, in association with lightning, were essential interactions that impacted TC-genesis. While our dust footprints hypothesis applied under strong dust conditions (i.e., TD 8), other factors (e.g., vertical wind shear, pre-existing vortex and trough location, thermodynamics) need to be evaluated as well. The results from this study suggest that the SAL is not a determining factor that affects the formation of tropical cyclones (i.e., TD 8 and TD 12).

  9. The footprints of Saharan air layer and lightning on the formation of tropical depressions over the eastern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Centeno Delgado, Diana C.; Chiao, Sen

    2015-02-01

    The roles of the Saharan Air Layer (SAL) and lightning during genesis of Tropical Depression (TD) 8 (2006) and TD 12 (2010) were investigated in relation to the interaction of the dust outbreaks with each system and their surrounding environment. This study applied data collected from the 2006 NASA African Monsoon Multidisciplinary Analysis and 2010 Genesis and Rapid Intensification Processes projects. Satellite observations from METEOSAT and Moderate Resolution Imaging Spectroradiometer (MODIS)—Aerosol Optical Depth (AOD) were also employed for the study of the dust content. Lightning activity data from the Met Office Arrival Time Difference (ATD) system were used as another parameter to correlate moist convective overturning and a sign of cyclone formation. The AOD and lightning analysis for TD 8 demonstrated the time-lag connection through their positive contribution to TC-genesis. TD 12 developed without strong dust outbreak, but with lower wind shear (2 m s-1) and an organized Mesoscale Convective System (MCS). Overall, the results from the combination of various data analyses in this study support the fact that both systems developed under either strong or weak dust conditions. From these two cases, the location (i.e., the target area) of strong versus weak dust outbreaks, in association with lightning, were essential interactions that impacted TC-genesis. While our dust footprints hypothesis applied under strong dust conditions (i.e., TD 8), other factors (e.g., vertical wind shear, pre-existing vortex and trough location, thermodynamics) need to be evaluated as well. The results from this study suggest that the SAL is not a determining factor that affects the formation of tropical cyclones (i.e., TD 8 and TD 12).

  10. Infrared propagation in the air-sea boundary layer

    NASA Astrophysics Data System (ADS)

    Larsen, R.; Preedy, K. A.; Drake, G.

    1990-03-01

    Over the oceans and other large bodies of water the structure of the lowest layers of the atmosphere is often strongly modified by evaporation of water vapor from the water surface. At radio wavelengths this layer will usually be strongly refracting or ducting, and the layer is commonly known as the evaporation duct. However, the refractive index of air at infrared wavelengths differs from that at radio wavelengths, and the effects of the marine boundary layer on the propagation of infrared radiation are examined. Meteorological models of the air-sea boundary layer are used to compute vertical profiles of temperature and water-vapor pressure. From these are derived profiles of atmospheric refractive index at radio wavelengths and at infrared wavelengths in the window regions of low absorption. For duct propagation to occur it is necessary that the refractivity of air decreases rapidly with increasing height above the surface. At radio wavelengths this usually occurs when there is a strong lapse of water vapor pressure with increasing height. By contrast, at infrared wavelengths the refractive index is almost independent of water vapor pressure, and it is found that an infrared duct is formed only when there is a temperature inversion.

  11. Air Flow in a Separating Laminar Boundary Layer

    NASA Technical Reports Server (NTRS)

    Schubauer, G B

    1936-01-01

    The speed distribution in a laminar boundary layer on the surface of an elliptic cylinder, of major and minor axes 11.78 and 3.98 inches, respectively, has been determined by means of a hot-wire anemometer. The direction of the impinging air stream was parallel to the major axis. Special attention was given to the region of separation and to the exact location of the point of separation. An approximate method, developed by K. Pohlhausen for computing the speed distribution, the thickness of the layer, and the point of separation, is described in detail; and speed-distribution curves calculated by this method are presented for comparison with experiment.

  12. The footprints of Saharan Air Layer and lightning on the formation of tropical depressions over the eastern Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Centeno Delgado, Diana C.

    In this study, the results of an observational analysis and a numerical analysis on the role of the Saharan Air Layer during tropical cyclogenesis (TC-genesis) are described. The observational analysis investigates the interaction of dust particles and lightning during the genesis stage of two developed cases (Hurricanes Helene 2006 and Julia 2010). The Weather Research and Forecasting (WRF) and WRF-Chemistry models were used to include and monitor the aerosols and chemical processes that affect TC-genesis. The numerical modeling involved two developed cases (Hurricanes Helene 2006 and Julia 2010) and two non-developed cases (Non-Developed 2011 and Non-Developed 2012). The Aerosol Optical Depth (AOD) and lightning analysis for Hurricane Helene 2006 demonstrated the time-lag connection through their positive contribution to TC-genesis. The observational analyses supported the fact that both systems developed under either strong or weak dust conditions. From the two cases, the location of strong versus weak dust outbreaks in association with lightning was essential interactions that impacted TC-genesis. Furthermore, including dust particles, chemical processes, and aerosol feedback in the simulations with WRF-CHEM provides results closer to observations than regular WRF. The model advantageously shows the location of the dust particles inside of the tropical system. Overall, the results from this study suggest that the SAL is not a determining factor that affects the formation of tropical cyclones.

  13. Air motion determination by tracking humidity patterns in isentropic layers

    NASA Technical Reports Server (NTRS)

    Mancuso, R. L.; Hall, D. J.

    1975-01-01

    Determining air motions by tracking humidity patterns in isentropic layers was investigated. Upper-air rawinsonde data from the NSSL network and from the AVE-II pilot experiment were used to simulate temperature and humidity profile data that will eventually be available from geosynchronous satellites. Polynomial surfaces that move with time were fitted to the mixing-ratio values of the different isentropic layers. The velocity components of the polynomial surfaces are part of the coefficients that are determined in order to give an optimum fitting of the data. In the mid-troposphere, the derived humidity motions were in good agreement with the winds measured by rawinsondes so long as there were few or no clouds and the lapse rate was relatively stable. In the lower troposphere, the humidity motions were unreliable primarily because of nonadiabatic processes and unstable lapse rates. In the upper troposphere, the humidity amounts were too low to be measured with sufficient accuracy to give reliable results. However, it appears that humidity motions could be used to provide mid-tropospheric wind data over large regions of the globe.

  14. Direct Numerical Simulation of Air Layer Drag Reduction over a Backward-facing Step

    NASA Astrophysics Data System (ADS)

    Kim, Dokyun; Moin, Parviz

    2010-11-01

    Direct Numerical Simulation (DNS) of two-phase flow is performed to investigate the air layer drag reduction (ALDR) phenomenon in turbulent flow over a backward-facing step. In their experimental study, Elbing et al. (JFM, 2008) have observed a stable air layer on an entire flat plate if air is injected beyond the critical air-flow rate. In the present study, air is injected at the step on the wall into turbulent water flow for ALDR. The Reynolds and Weber numbers based on the water properties and step height are 22,800 and 560, respectively. An inlet section length before the step is 3h and the post expansion length is 30h, where h is the step height. The total number of grid points is about 271 million for DNS. The level set method is used to track the phase interface and the structured-mesh finite volume solver is used with an efficient algorithm for two-phase DNS. Two cases with different air-flow rates are performed to investigate the mechanism and stability of air layer. For high air-flow rate, the stable air layer is formed on the plate and more than 90% drag reduction is obtained. In the case of low air-flow rate, the air layer breaks up and ALDR is not achieved. The parameters governing the stability of air layer from the numerical simulations is also consistent with the results of stability analysis.

  15. Experimental investigation of frictional resistance reduction with air layer on the hull bottom of a ship

    NASA Astrophysics Data System (ADS)

    Jang, Jinho; Choi, Soon Ho; Ahn, Sung-Mok; Kim, Booki; Seo, Jong Soo

    2014-06-01

    In an effort to cope with recent high oil price and global warming, developments of air lubricated ships have been pursued to reduce greenhouse gas emissions and to save fuel costs by reducing the frictional resistance. In this study, reduction in the frictional resistance by air lubrication with air layers generated on the lower surface of a flat plate was investigated experimentally in the large water tunnel of SSMB. The generated air layers were observed, and changes in the local frictional drag were measured at various flow rates of injected air. The results indicated that air lubrication with air layers might be useful in reducing the frictional resistance at specific conditions of air injection. Accordingly, resistance and self-propulsion tests for a 66K DWT bulk carrier were carried out in the towing tank of SSMB to estimate the expected net power savings.

  16. Formation of elevated refractive layers in the oceanic boundary layer by modification of land air flowing offshore

    NASA Astrophysics Data System (ADS)

    Gossard, Earl E.

    1982-03-01

    The usual picture of the development of temperature and humidity boundary layers in a land air mass that moves offshore is shown to be very wrong under one type of Foehn condition in southern California, and it is probable that similar conditions can prevail in widespread areas around the globe, notably the Mediterranean Sea and the monsoonal regions of the Near East and Southeast Asia. A formalism is developed for analyzing the modification that seems to represent the observations satisfactorily, and graphical solutions for radio and optical ducting are given. It is shown that offshore modification can lead to elevated layers rather than to surface based layers, and the height of the layer base is theoretically predicted. Values of evaporation and heat flux into such an air mass are calculated, and the distance offshore at which dew point depression becomes zero is predicted. A method for measuring the downward heat flux in elevated inversion layers is described and results are given.

  17. Modeling and Analysis of Asynchronous Systems Using SAL and Hybrid SAL

    NASA Technical Reports Server (NTRS)

    Tiwari, Ashish; Dutertre, Bruno

    2013-01-01

    We present formal models and results of formal analysis of two different asynchronous systems. We first examine a mid-value select module that merges the signals coming from three different sensors that are each asynchronously sampling the same input signal. We then consider the phase locking protocol proposed by Daly, Hopkins, and McKenna. This protocol is designed to keep a set of non-faulty (asynchronous) clocks phase locked even in the presence of Byzantine-faulty clocks on the network. All models and verifications have been developed using the SAL model checking tools and the Hybrid SAL abstractor.

  18. Measuring air layer volumes retained by submerged floating-ferns Salvinia and biomimetic superhydrophobic surfaces.

    PubMed

    Mayser, Matthias J; Bohn, Holger F; Reker, Meike; Barthlott, Wilhelm

    2014-01-01

    Some plants and animals feature superhydrophobic surfaces capable of retaining a layer of air when submerged under water. Long-term air retaining surfaces (Salvinia-effect) are of high interest for biomimetic applications like drag reduction in ship coatings of up to 30%. Here we present a novel method for measuring air volumes and air loss under water. We recorded the buoyancy force of the air layer on leaf surfaces of four different Salvinia species and on one biomimetic surface using a highly sensitive custom made strain gauge force transducer setup. The volume of air held by a surface was quantified by comparing the buoyancy force of the specimen with and then without an air layer. Air volumes retained by the Salvinia-surfaces ranged between 0.15 and 1 L/m(2) depending on differences in surface architecture. We verified the precision of the method by comparing the measured air volumes with theoretical volume calculations and could find a good agreement between both values. In this context we present techniques to calculate air volumes on surfaces with complex microstructures. The introduced method also allows to measure decrease or increase of air layers with high accuracy in real-time to understand dynamic processes. PMID:24991518

  19. Multi-layered, chemically bonded lithium-ion and lithium/air batteries

    SciTech Connect

    Narula, Chaitanya Kumar; Nanda, Jagjit; Bischoff, Brian L; Bhave, Ramesh R

    2014-05-13

    Disclosed are multilayer, porous, thin-layered lithium-ion batteries that include an inorganic separator as a thin layer that is chemically bonded to surfaces of positive and negative electrode layers. Thus, in such disclosed lithium-ion batteries, the electrodes and separator are made to form non-discrete (i.e., integral) thin layers. Also disclosed are methods of fabricating integrally connected, thin, multilayer lithium batteries including lithium-ion and lithium/air batteries.

  20. Bandgap Restructuring of the Layered Semiconductor Gallium Telluride in Air.

    PubMed

    Fonseca, Jose J; Tongay, Sefaattin; Topsakal, Mehmet; Chew, Annabel R; Lin, Alan J; Ko, Changhyun; Luce, Alexander V; Salleo, Alberto; Wu, Junqiao; Dubon, Oscar D

    2016-08-01

    A giant bandgap reduction in layered GaTe is demonstrated. Chemisorption of oxygen to the Te-terminated surfaces produces significant restructuring of the conduction band resulting in a bandgap below 0.8 eV, compared to 1.65 eV for pristine GaTe. Localized partial recovery of the pristine gap is achieved by thermal annealing, demonstrating that reversible band engineering in layered semiconductors is accessible through their surfaces. PMID:27171481

  1. Turbulent Boundary Layer in High Rayleigh Number Convection in Air

    NASA Astrophysics Data System (ADS)

    du Puits, Ronald; Li, Ling; Resagk, Christian; Thess, André; Willert, Christian

    2014-03-01

    Flow visualizations and particle image velocimetry measurements in the boundary layer of a Rayleigh-Bénard experiment are presented for the Rayleigh number Ra =1.4×1010. Our visualizations indicate that the appearance of the flow structures is similar to ordinary (isothermal) turbulent boundary layers. Our particle image velocimetry measurements show that vorticity with both positive and negative sign is generated and that the smallest flow structures are 1 order of magnitude smaller than the boundary layer thickness. Additional local measurements using laser Doppler velocimetry yield turbulence intensities up to I=0.4 as in turbulent atmospheric boundary layers. From our observations, we conclude that the convective boundary layer becomes turbulent locally and temporarily although its Reynolds number Re ≈200 is considerably smaller than the value 420 underlying existing phenomenological theories. We think that, in turbulent Rayleigh-Bénard convection, the transition of the boundary layer towards turbulence depends on subtle details of the flow field and is therefore not universal.

  2. Boundary layer flow of air over water on a flat plate

    NASA Technical Reports Server (NTRS)

    Nelson, John; Alving, Amy E.; Joseph, Daniel D.

    1993-01-01

    A non-similar boundary layer theory for air blowing over a water layer on a flat plate is formulated and studied as a two-fluid problem in which the position of the interface is unknown. The problem is considered at large Reynolds number (based on x), away from the leading edge. A simple non-similar analytic solution of the problem is derived for which the interface height is proportional to x(sub 1/4) and the water and air flow satisfy the Blasius boundary layer equations, with a linear profile in the water and a Blasius profile in the air. Numerical studies of the initial value problem suggests that this asymptotic, non-similar air-water boundary layer solution is a global attractor for all initial conditions.

  3. Atmospheric Boundary Layer Modeling for Combined Meteorology and Air Quality Systems

    EPA Science Inventory

    Atmospheric Eulerian grid models for mesoscale and larger applications require sub-grid models for turbulent vertical exchange processes, particularly within the Planetary Boundary Layer (PSL). In combined meteorology and air quality modeling systems consistent PSL modeling of wi...

  4. Detailed cloud resolving model simulations of the impacts of Saharan air layer dust on tropical deep convection - Part 1: Dust acts as ice nuclei

    NASA Astrophysics Data System (ADS)

    Gong, W.; Min, Q.; Li, R.; Teller, A.; Joseph, E.; Morris, V.

    2010-05-01

    Observational studies suggest that the Saharan Air Layer (SAL), an elevated layer (850-500 hPa) of Saharan air and mineral dust, has strong impacts on the microphysical as well as dynamical properties of tropical deep convective cloud systems along its track. In this case study, numerical simulations using a two-dimensional Detailed Cloud Resolving Model (DCRM) were carried out to investigate the dust-cloud interactions in the tropical deep convection, focusing on the dust role as Ice Nuclei (IN). The simulations showed that mineral dust considerably enhanced heterogeneous nucleation and freezing at temperatures warmer than -40 °C, resulting in more ice hydrometeors number concentration and reduced precipitating size of ice particles. Because of the lower in the saturation over ice as well as more droplet freezing, total latent heating increased, and consequently the updraft velocity was stronger. On the other hand, the increased ice deposition consumed more water vapor at middle troposphere, which induces a competition for water vapor between heterogeneous and homogeneous freezing and nucleation. As a result, dust suppressed the homogeneous droplet freezing and nucleation due to the heterogeneous droplet freezing and the weakened transport of water vapor at lower stratosphere, respectively. These effects led to decreased number concentration of ice cloud particles in the upper troposphere, and consequently lowered the cloud top height during the stratus precipitating stage. Acting as IN, mineral dust also influenced precipitation in deep convection. It initiated earlier the collection because dust-related heterogeneous nucleation and freezing at middle troposphere occur earlier than homogeneous nucleation at higher altitudes. Nevertheless, the convective precipitation was suppressed by reduced collection of large graupel particles and insufficient fallout related to decreased sizes of precipitating ice hydrometeors. On the contrary, dust increased the

  5. The Impact of Dry Saharan Air on Tropical Cyclone Intensification

    NASA Technical Reports Server (NTRS)

    Braun, Scott A.

    2012-01-01

    The controversial role of the dry Saharan Air Layer (SAL) on tropical storm intensification in the Atlantic will be addressed. The SAL has been argued in previous studies to have potential positive influences on storm development, but most recent studies have argued for a strong suppressing influence on storm intensification as a result of dry air, high stability, increased vertical wind shear, and microphysical impacts of dust. Here, we focus on observations of Hurricane Helene (2006), which occurred during the NASA African Monsoon Multidisciplinary Activities (NAMMA) experiment. Satellite and airborne observations, combined with global meteorological analyses depict the initial environment of Helene as being dominated by the SAL, although with minimal evidence that the SAL air actually penetrated to the core of the disturbance. Over the next several days, the SAL air quickly moved westward and was gradually replaced by a very dry, dust-free layer associated with subsidence. Despite the wrapping of this very dry air around the storm, Helene intensified steadily to a Category 3 hurricane suggesting that the dry air was unable to significantly slow storm intensification. Several uncertainties remain about the role of the SAL in Helene (and in tropical cyclones in general). To better address these uncertainties, NASA will be conducting a three year airborne campaign called the Hurricane and Severe Storm Sentinel (HS3). The HS3 objectives are: To obtain critical measurements in the hurricane environment in order to identify the role of key factors such as large-scale wind systems (troughs, jet streams), Saharan air masses, African Easterly Waves and their embedded critical layers (that help to isolate tropical disturbances from hostile environments). To observe and understand the three-dimensional mesoscale and convective-scale internal structures of tropical disturbances and cyclones and their role in intensity change. The mission objectives will be achieved using

  6. Intra- and Interspecies Signaling between Streptococcus salivarius and Streptococcus pyogenes Mediated by SalA and SalA1 Lantibiotic Peptides

    PubMed Central

    Upton, M.; Tagg, J. R.; Wescombe, P.; Jenkinson, H. F.

    2001-01-01

    Streptococcus salivarius 20P3 produces a 22-amino-acid residue lantibiotic, designated salivaricin A (SalA), that inhibits the growth of a range of streptococci, including all strains of Streptococcus pyogenes. Lantibiotic production is associated with the sal genetic locus comprising salA, the lantibiotic structural gene; salBCTX genes encoding peptide modification and export machinery proteins; and salYKR genes encoding a putative immunity protein and two-component sensor-regulator system. Insertional inactivation of salB in S. salivarius 20P3 resulted in abrogation of SalA peptide production, of immunity to SalA, and of salA transcription. Addition of exogenous SalA peptide to salB mutant cultures induced dose-dependent expression of salA mRNA (0.2 kb), demonstrating that SalA production was normally autoregulated. Inactivation of salR encoding the response regulator of the SalKR two-component system led to reduced production of, and immunity to, SalA. The sal genetic locus was also present in S. pyogenes SF370 (M type 1), but because of a deletion across the salBCT genes, the corresponding lantibiotic peptide, designated SalA1, was not produced. However, in S. pyogenes T11 (M type 4) the sal locus gene complement was apparently complete, and active SalA1 peptide was synthesized. Exogenously added SalA1 peptide from S. pyogenes T11 induced salA1 transcription in S. pyogenes SF370 and in an isogenic S. pyogenes T11 salB mutant and salA transcription in S. salivarius 20P3 salB. Thus, SalA and SalA1 are examples of streptococcal lantibiotics whose production is autoregulated. These peptides act as intra- and interspecies signaling molecules, modulating lantibiotic production and possibly influencing streptococcal population ecology in the oral cavity. PMID:11395456

  7. Performance improvement of a cross-flow hydro turbine by air layer effect

    NASA Astrophysics Data System (ADS)

    Choi, Y. D.; Yoon, H. Y.; Inagaki, M.; Ooike, S.; Kim, Y. J.; Lee, Y. H.

    2010-08-01

    The purpose of this study is not only to investigate the effects of air layer in the turbine chamber on the performance and internal flow of the cross-flow turbine, but also to suggest a newly developed air supply method. Field test is performed in order to measure the output power of the turbine by a new air supply method. CFD analysis on the performance and internal flow of the turbine is conducted by an unsteady state calculation using a two-phase flow model in order to embody the air layer effect on the turbine performance effectively.The result shows that air layer effect on the performance of the turbine is considerable. The air layer located in the turbine runner passage plays the role of preventing a shock loss at the runner axis and suppressing a recirculation flow in the runner. The location of air suction hole on the chamber wall is very important factor for the performance improvement. Moreover, the ratio between air from suction pipe and water from turbine inlet is also significant factor of the turbine performance.

  8. R2 AIRS/AFS FACILITY GIS LAYER

    EPA Science Inventory

    The AFS subsystem contains emissions, compliance, and permit data for stationary sources regulated by the U.S. EPA and state and local air pollution agencies. This information is used by states in preparation of State Implementation Plans (SIPs), to track the compliance status ...

  9. Dynamic of Air Invasion in an Immersed Granular Layer

    NASA Astrophysics Data System (ADS)

    Varas, G.; Ramos, G.; Géminard, J. C.; Vidal, V.

    2014-12-01

    Displacement processes (typically, grains displaced by a fluid) are the driving mechanism which control the dynamics of many geological processes (e.g. oil extraction, air sparging, piercement structures). They also play an important role in a wide range of industrial applications, from ground water hydrology and soil mechanics to agricultural engineering. The interaction between one or more moving fluids (e.g. rising gas immersed in a granular medium) and grains control the dynamics of these phenomena. Due to their economic and ecological importance, it is essential to understand the variety and potentiality of these phenomena. When an ascending air passes trough an immersed granular bed its fluidized producing the grains to start to move. When this process is repeated, its created a fluidized zone that evolves over time. Here, we investigate the morphology and dynamics of the region invaded by air as a function of a dimensionless parameter χ which accounts for the relative effects of the gravity and the capillarity. We propose new experimental observations on the air invasion regimes and on the morphology of the fluidized zone, in particular its growth dynamics.

  10. Mixing layer growth and background air-quality measurements over the Colorado oil-shale area

    SciTech Connect

    Laulainen, N.S.; Whiteman, C.D.; Davis, W.E.; Thorp, J.M.

    1981-06-01

    The daily growth of convective boundary layers over the complex terrain of the oil shale areas of Colorado is a prominent feature of the meteorology of the region. The development of these layers was investigated using airsondes, rawinsondes, and aircraft. The deep growth of the layers in August, to heights in excess of 5500-m MSL on clear or partly cloudy days, is expected to have important implications for the dispersal of pollutants released in the region as the oil shale resource undergoes future development. Aircraft observations show that the present background air quality is good over the region and that pollutants, when present, become well mixed throughout the depth of the convective boundary layer. The layer therefore represents an important natural means of dilution for pollutants introduced into the atmosphere. Work is proceeding to incorporate the time-dependent convective boundary layer growth into air pollution models for the region.

  11. Uncertainty Analysis of Air Radiation for Lunar Return Shock Layers

    NASA Technical Reports Server (NTRS)

    Kleb, Bil; Johnston, Christopher O.

    2008-01-01

    By leveraging a new uncertainty markup technique, two risk analysis methods are used to compute the uncertainty of lunar-return shock layer radiation predicted by the High temperature Aerothermodynamic Radiation Algorithm (HARA). The effects of epistemic uncertainty, or uncertainty due to a lack of knowledge, is considered for the following modeling parameters: atomic line oscillator strengths, atomic line Stark broadening widths, atomic photoionization cross sections, negative ion photodetachment cross sections, molecular bands oscillator strengths, and electron impact excitation rates. First, a simplified shock layer problem consisting of two constant-property equilibrium layers is considered. The results of this simplified problem show that the atomic nitrogen oscillator strengths and Stark broadening widths in both the vacuum ultraviolet and infrared spectral regions, along with the negative ion continuum, are the dominant uncertainty contributors. Next, three variable property stagnation-line shock layer cases are analyzed: a typical lunar return case and two Fire II cases. For the near-equilibrium lunar return and Fire 1643-second cases, the resulting uncertainties are very similar to the simplified case. Conversely, the relatively nonequilibrium 1636-second case shows significantly larger influence from electron impact excitation rates of both atoms and molecules. For all cases, the total uncertainty in radiative heat flux to the wall due to epistemic uncertainty in modeling parameters is 30% as opposed to the erroneously-small uncertainty levels (plus or minus 6%) found when treating model parameter uncertainties as aleatory (due to chance) instead of epistemic (due to lack of knowledge).

  12. The relationship between air layers and evaporative resistance of male Chinese ethnic clothing.

    PubMed

    Wang, Faming; Peng, Hui; Shi, Wen

    2016-09-01

    In this study, the air layer distribution and evaporative resistances of 39 sets of male Chinese ethnic clothing were investigated using a sweating thermal manikin and the three-dimensional (3D) body scanning technique. Relationships between the evaporative resistance and air layers (i.e., air gap thickness and air volume) were explored. The results demonstrated that the clothing total evaporative resistance increases with the increasing air gap size/air volume, but the rate of increase gradually decreases as the mean air gap size or the total air volume becomes larger. The clothing total evaporative resistance reaches its maximum when the average air gap size and the total air volume are 41.6 mm and 69.9 dm(3), respectively. Similar general trends were also found between local mean air gap size and clothing local evaporative resistance at different body parts. However, different body parts show varied rates of increase and decrease in the local evaporative resistance. The research findings provide a comprehensive database for predicting overall and local human thermal comfort while wearing male Chinese ethnic clothing. PMID:27184328

  13. Simulating SAL formation and aerosol size distribution during SAMUM-I

    NASA Astrophysics Data System (ADS)

    Khan, Basit; Stenchikov, Georgiy; Weinzierl, Bernadett; Kalenderski, Stoitchko; Osipov, Sergey

    2015-04-01

    To understand the formation mechanisms of Saharan Air Layer (SAL), we combine model simulations and dust observations collected during the first stage of the Saharan Mineral Dust Experiment (SAMUM-I), which sampled dust events that extended from Morocco to Portugal, and investigated the spatial distribution and the microphysical, optical, chemical, and radiative properties of Saharan mineral dust. We employed the Weather Research Forecast model coupled with the Chemistry/Aerosol module (WRF-Chem) to reproduce the meteorological environment and spatial and size distributions of dust. The experimental domain covers northwest Africa including the southern Sahara, Morocco and part of the Atlantic Ocean with 5 km horizontal grid spacing and 51 vertical layers. The experiments were run from 20 May to 9 June 2006, covering the period of most intensive dust outbreaks. Comparisons of model results with available airborne and ground-based observations show that WRF-Chem reproduces observed meteorological fields as well as aerosol spatial distribution across the entire region and along the airplane's tracks. We evaluated several aerosol uplift processes and found that orographic lifting, aerosol transport through the land/sea interface with steep gradients of meteorological characteristics, and interaction of sea breezes with the continental outflow are key mechanisms that form a surface-detached aerosol plume over the ocean. Comparisons of simulated dust size distributions with airplane and ground-based observations are generally good, but suggest that more detailed treatment of microphysics in the model is required to capture the full-scale effect of large aerosol particles.

  14. Bonding of copper surface in ambient air using propylene carbonate as passivation layer

    NASA Astrophysics Data System (ADS)

    Zhu, Zhiyuan; Yu, Min; Phillips, Oluwadamilola; Liu, Lisha; Jin, Yufeng

    2015-07-01

    Bonding of a copper surface in a nonvacuum environment has been studied for the purpose of reducing manufacturing costs. Cu-Cu bonding in ambient air is demonstrated by using propylene carbonate (PPC) as a passivation layer. The decomposition of the PPC passivation layer during bonding would protect the copper surface from oxidation by providing a shielding gas atmosphere between the copper surface and the air. Further, the PPC passivation layer would also overcome the degradation of copper surface during storage in the atmosphere.

  15. Leaping shampoo glides on a 500-nm-thick lubricating air layer

    NASA Astrophysics Data System (ADS)

    Li, Erqiang; Lee, Sanghyun; Marston, Jeremy; Bonito, Andrea; Thoroddsen, Sigurdur

    2013-11-01

    When a stream of shampoo is fed onto a pool in one's hand, a jet can leap sideways or rebound from the liquid surface in an intriguing phenomenon known as the Kaye effect. Earlier studies have debated whether non-Newtonian effects are the underlying cause of this phenomenon, making the jet glide on top of a shear-thinning liquid layer, or whether an entrained air layer is responsible. Herein we show unambiguously that the jet slides on a lubricating air layer [Lee et al., Phys. Rev. E 87, 061001 (2013)]. We identify this layer by looking through the pool liquid and observing its rupture into fine micro-bubbles. The resulting micro-bubble sizes suggest that the thickness of this air layer is around 500 nm. This thickness estimate is also supported by the tangential deceleration of the jet during the rebounding, with the shear stress within the thin air layer sufficient for the observed deceleration. Particle tracking within the jet shows uniform velocity, with no pronounced shear, which would be required for shear-thinning effects. The role of the surfactant may primarily be to stabilize the air film.

  16. Formation and Evaluation of Protective Layer over Magnesium Melt Under CO2/Air Mixtures

    NASA Astrophysics Data System (ADS)

    Emami, Samar; Sohn, Hong Yong

    2015-02-01

    Molten magnesium oxidizes rapidly when exposed to air causing melt loss and handling difficulties. The use of certain additive gases to form a protective MgO layer over a magnesium melt has been proposed. The oxidation behavior of molten magnesium in air that contains various concentrations of CO2 was investigated, including the kinetics of the oxide layer growth. Experiments were performed using a thermogravimetric analysis unit in the temperature range of 943 K to 1043 K (670 °C to 770 °C). Results showed that a thin, coherent, and protective MgO-C layer was formed under the test conditions. The thicknesses of this layer formed under CO2/air ranged from 500 nm to 12 μm. Rate parameters were calculated and a model for the process was developed. The morphology and composition of the surface films were studied using SEM and EDS.

  17. Factors influencing the marine boundary layer during a cold-air outbreak

    NASA Technical Reports Server (NTRS)

    Stage, S. A.

    1983-01-01

    The model for the cloud-topped marine boundary layer during a cold air outbreak developed by Stage and Businger (1981a) is used in conjunction with a test profile based on a fall outbreak episode over Lake Ontario to study factors influencing marine boundary-layer evolution. Sensitivity tests are done which show changes in layer evolution resulting from variation of wind speed, radiative sky temperature, water surface temperature, humidity of the shoreline sounding and divergence. The behavior of the layer in the presence of a region of cold-water upwelling near the shore is also investigated. It is found that the main effect of the upwelling region is to delay modification of the boundary-layer air.

  18. Impact of Bay-Breeze Circulations on Surface Air Quality and Boundary Layer Export

    NASA Technical Reports Server (NTRS)

    Loughner, Christopher P.; Tzortziou, Maria; Follette-Cook, Melanie; Pickering, Kenneth E.; Goldberg, Daniel; Satam, Chinmay; Weinheimer, Andrew; Crawford, James H.; Knapp, David J.; Montzka, Denise D.; Diskin, Glenn S.; Dickerson, Russell R.

    2014-01-01

    Meteorological and air-quality model simulations are analyzed alongside observations to investigate the role of the Chesapeake Bay breeze on surface air quality, pollutant transport, and boundary layer venting. A case study was conducted to understand why a particular day was the only one during an 11-day ship-based field campaign on which surface ozone was not elevated in concentration over the Chesapeake Bay relative to the closest upwind site and why high ozone concentrations were observed aloft by in situ aircraft observations. Results show that southerly winds during the overnight and early-morning hours prevented the advection of air pollutants from the Washington, D.C., and Baltimore, Maryland, metropolitan areas over the surface waters of the bay. A strong and prolonged bay breeze developed during the late morning and early afternoon along the western coastline of the bay. The strength and duration of the bay breeze allowed pollutants to converge, resulting in high concentrations locally near the bay-breeze front within the Baltimore metropolitan area, where they were then lofted to the top of the planetary boundary layer (PBL). Near the top of the PBL, these pollutants were horizontally advected to a region with lower PBL heights, resulting in pollution transport out of the boundary layer and into the free troposphere. This elevated layer of air pollution aloft was transported downwind into New England by early the following morning where it likely mixed down to the surface, affecting air quality as the boundary layer grew.

  19. Application of high intensity air-borne ultrasound for debubbling liquid coating layers.

    PubMed

    González, I; Rodríguez, J; Garmendia, I; Gallego-Juárez, J A

    2006-12-22

    In the coating processes, the formation of bubbles and microbubbles is relatively frequent inside the coating layer. Such bubbles, which are formed as a consequence of air retention, are difficult to remove and specifically in high-speed (quick-drying) industrial application where they cause permanent imperfections in the homogeneity of the layer. High-intensity air-borne ultrasound may represent a clean means to improve homogenization by quickly breaking the bubbles just when they are formed inside the coating film. This paper deals with the direct application of air-borne high-intensity ultrasonic radiation at a frequency of about 21 kHz over coating layers just immediately they have been deposited over wood substrates. Such novel process has been implemented and experimentally studied at laboratory and semi-industrial stages. PMID:16797638

  20. Morphology of air invasion in an immersed granular layer.

    PubMed

    Varas, Germán; Vidal, Valérie; Géminard, Jean-Christophe

    2011-06-01

    We report a study of the paths formed by a finite volume of air gently injected at the base of an immersed granular material. A two-dimensional model, based on experimental observations, shows that the typical height and width of the region explored by the branched path depends not only on the injected volume V, but also on a dimensionless parameter χ which accounts for the relative effects of the gravity and capillarity. For a given injected volume V, larger gravity effects lead to taller and narrower structures; for a given χ, the typical height and width of the structure scale like V(1/2) and V(1/4), respectively, while the typical gaseous fraction in the corresponding region increases accordingly like V(1/4). Such results can be of practical importance: For instance, gas can be trapped on purpose in an underground natural container below a granular slurry. Our results can help in predicting if the gas is likely to reach the free surface and escape the system if the container presents a defect (hole or fracture). PMID:21797353

  1. Effects of boundary layer and liquid viscosity and compressible air on sloshing characteristics

    NASA Astrophysics Data System (ADS)

    Zou, Chang-Fang; Wang, De-Yu; Cai, Zhong-Hua

    2015-07-01

    In this paper, numerical investigations for tank sloshing, based on commercial CFD package FLUENT, are performed to study effects of boundary layer grid, liquid viscosity and compressible air on sloshing pressure, wave height and rising time of impact pressure. Also, sloshing experiments for liquids of different viscosity are carried out to validate the numerical results. Through comparison of numerical and experimental results, a computational model including boundary layer grid can predict the sloshing pressure more accurately. Energy dissipation due to viscous friction leads to reduction of sloshing pressure and wave elevation. Sloshing pressure is also reduced because of cushion effect of compressible air. Due to high viscosity damping effect and compressible air effect, the rising time of impact pressure becomes longer. It is also found that liquid viscosity and compressible air influence distribution of dynamic pressure along the vertical tank wall.

  2. Dynamical Simulation of Cloudy Boundary Layer Flow during Cold Air Outbreaks.

    NASA Astrophysics Data System (ADS)

    Yuen, Chiu-Wai

    A two-dimensional primitive equation planetary boundary layer model has been constructed and applied to simulate downwind evolution of coupled dynamical, thermodynamical and cloud properties in the planetary boundary layer (PBL) developed during cold air outbreaks over warm ocean. A layered parametric approach is adopted to model the inversion -capped convective boundary layer filled with shallow cumuli, or topped by stratocumulus or cloud free air. Turbulent and convective cloud fluxes are determined from modifications and generalizations of recent published parameterization schemes. A one-dimensional version of the model is first applied to a local simulation of trade wind flow. Vertical distributions of momentum flux and wind in the cumulus -filled baroclinic PBL are realistically simulated compared to observations, confirming the validity of the momentum flux parameterization scheme assembled in this research. A steady-state linear analysis for a cloud-free mixed layer flowing from land over a warm ocean clarifies the basic dynamical and thermodynamical adjustments to differential friction and heating. Downwind warming and deepening of PBL produces counteracting pressure gradient forces, while heating-induced subsidence occurs only in places where boundary layer baroclinity is strong. Comparative numerical experiments for moderate intensity air-sea interaction illustrate the importance of nonprecipitating cumulus convection and large scale environmental conditions. Such factors as baroclinity, static stability, moisture content, upwind inversion strength and height exert strong controls on the downwind evolution of PBL and clouds. Boundary layer flow is influenced by the basic geostrophic wind distribution and the PBL depth is also sensitive to large scale vertical velocity. The response of an advective boundary layer to stronger wind is different from that of a horizontally homogeneous boundary layer. In a simulation of an intense air mass transformation

  3. Air-Impregnated Nanoporous Anodic Aluminum Oxide Layers for Enhancing the Corrosion Resistance of Aluminum.

    PubMed

    Jeong, Chanyoung; Lee, Junghoon; Sheppard, Keith; Choi, Chang-Hwan

    2015-10-13

    Nanoporous anodic aluminum oxide layers were fabricated on aluminum substrates with systematically varied pore diameters (20-80 nm) and oxide thicknesses (150-500 nm) by controlling the anodizing voltage and time and subsequent pore-widening process conditions. The porous nanostructures were then coated with a thin (only a couple of nanometers thick) Teflon film to make the surface hydrophobic and trap air in the pores. The corrosion resistance of the aluminum substrate was evaluated by a potentiodynamic polarization measurement in 3.5 wt % NaCl solution (saltwater). Results showed that the hydrophobic nanoporous anodic aluminum oxide layer significantly enhanced the corrosion resistance of the aluminum substrate compared to a hydrophilic oxide layer of the same nanostructures, to bare (nonanodized) aluminum with only a natural oxide layer on top, and to the latter coated with a thin Teflon film. The hydrophobic nanoporous anodic aluminum oxide layer with the largest pore diameter and the thickest oxide layer (i.e., the maximized air fraction) resulted in the best corrosion resistance with a corrosion inhibition efficiency of up to 99% for up to 7 days. The results demonstrate that the air impregnating the hydrophobic nanopores can effectively inhibit the penetration of corrosive media into the pores, leading to a significant improvement in corrosion resistance. PMID:26393523

  4. Influence of the air Layer Between the Conductor and the Layer Ofinsulating Material in Cable Products

    NASA Astrophysics Data System (ADS)

    Ivanova, Evgenia V.; Yashutina, Olga S.; Shidlovskiy, Stanisla V.

    2016-02-01

    There are developed mathematical model of physical and chemical processes of polymerization adhesive coating stranded cable. There are shown difference in the temperature distribution along the radius of the finished product in the presence of an air gap between the conductor and the rubber sheath. Also, due to the need to change process parameters with possible loose contacts inside the cable. Such as the temperature of the heating surface, feeding speed and dwell time in the oven.

  5. Experimental study on flat plate air solar collector using a thin sand layer

    NASA Astrophysics Data System (ADS)

    Lati, Moukhtar; Boughali, Slimane; Bouguettaia, Hamza; Mennouche, Djamel; Bechki, Djamel

    2016-07-01

    A flat plate air solar collector was constructed in the laboratory of New and Renewable Energy in Arid Zones LENREZA, Ouargla University-South East Algeria. The absorber of the flat plate air solar collector was laminated with a thin layer of local sand. This acted as a thermal storage system (packed bed) with a collecting area of 2.15 m2 (0.86 m × 2.5 m). It was noticed that the solar heater integrated with the thermal storage material delivered comparatively higher temperatures; thus, giving a better efficiency than the air heater without the thermal storage system.

  6. A laser Doppler system for the remote sensing of boundary layer winds in clear air conditions

    NASA Technical Reports Server (NTRS)

    Lawrence, T. R.; Krause, M. C.; Craven, C. E.; Morrison, L. K.; Thomson, J. A. L.; Cliff, W. C.; Huffaker, R. M.

    1975-01-01

    The system discussed uses a laser Doppler radar in combination with a velocity azimuth display mode of scanning to determine the three-dimensional wind field in the atmospheric boundary layer. An attractive feature of this CW monostatic system is that the ambient aerosol provides a 'sufficient' scattering target to permit operation under clear air conditions. Spatial resolution is achieved by focusing.

  7. Steam and air co-injection in removing residual TCE in unsaturated layered sandy porous media

    NASA Astrophysics Data System (ADS)

    Peng, Sheng; Wang, Ning; Chen, Jiajun

    2013-10-01

    Steam and air co-injection is a promising technique for volatile and semi-volatile organic contaminant remediation in heterogeneous porous media. In this study, removal of trichloroethene (TCE) with steam-air co-injection was investigated through a series of 2D sandbox experiments with different layered sand structures, and through numerical simulations. The results show that a layered structure with coarse sand, in which steam and air convection are relatively rapid, resulted in a higher removal rate and a larger removal ratio than those observed in an experiment using finer sand; however, the difference was not significant, and the removal ratios from three experiments ranged from 85% to 94%. Slight downward movement of TCE was observed for Experiment 1 (TCE initially in a fine sand zone encased in a coarse sand), while no such movement was observed for Experiment 2 (TCE initially in two fine sand layers encased in a coarse sand) or 3 (TCE initially in a silty sand zone encased in a coarse sand). Simulations show accumulation of TCE at the interface of the layered sands, which indicates a capillary barrier effect in restraining the downward movement of TCE. This effect is illustrated further by a numerical experiment with homogeneous coarse sand, in which continuous downward TCE movement to the bottom of the sandbox was simulated. Another numerical experiment with higher water saturation was also conducted. The results illustrate a complicated influence of water saturation on TCE removal in a layered sand structure.

  8. Steam and air co-injection in removing residual TCE in unsaturated layered sandy porous media.

    PubMed

    Peng, Sheng; Wang, Ning; Chen, Jiajun

    2013-10-01

    Steam and air co-injection is a promising technique for volatile and semi-volatile organic contaminant remediation in heterogeneous porous media. In this study, removal of trichloroethene (TCE) with steam-air co-injection was investigated through a series of 2D sandbox experiments with different layered sand structures, and through numerical simulations. The results show that a layered structure with coarse sand, in which steam and air convection are relatively rapid, resulted in a higher removal rate and a larger removal ratio than those observed in an experiment using finer sand; however, the difference was not significant, and the removal ratios from three experiments ranged from 85% to 94%. Slight downward movement of TCE was observed for Experiment 1 (TCE initially in a fine sand zone encased in a coarse sand), while no such movement was observed for Experiment 2 (TCE initially in two fine sand layers encased in a coarse sand) or 3 (TCE initially in a silty sand zone encased in a coarse sand). Simulations show accumulation of TCE at the interface of the layered sands, which indicates a capillary barrier effect in restraining the downward movement of TCE. This effect is illustrated further by a numerical experiment with homogeneous coarse sand, in which continuous downward TCE movement to the bottom of the sandbox was simulated. Another numerical experiment with higher water saturation was also conducted. The results illustrate a complicated influence of water saturation on TCE removal in a layered sand structure. PMID:23962760

  9. The measurement of water vapour transfer rate through clothing system with air gap between layers

    NASA Astrophysics Data System (ADS)

    Oh, Ae-Gyeong

    2008-02-01

    The experiments described in this paper are designed to test the water vapour transfer rates through outdoor clothing system with air gap between layers under conditions more closely actual wear. It was adopted distance of 5 mm to ensure no disturbance of the air gap thickness between layers throughout the measurement period with all fabrics. The results have indicated that the water vapour transfer rates of clothing system decrease very slightly with time, it is shown that they approached nearly equilibrium state throughout the experiment. It is revealed that the water vapour transfer rates of the clothing system were ordered into groups determined by the type of waterproof breathable fabric as a shell layer being ordered.

  10. Numerical model of boundary-layer control using air-jet generated vortices

    NASA Astrophysics Data System (ADS)

    Henry, F. S.; Pearcey, H. H.

    1994-12-01

    Numerical calculations of the three-dimensional flowfield generated by pitched and skewed air jets issuing into an otherwise undisturbed turbulent boundary layer are presented. It is demonstrated that each such jet produces a single strong longitudinal vortex. The strength of the vortex, as inferred from its effect on the development of skin friction, is shown to be influenced by pitch and skew angles, exit velocity, and downstream distance in ways which accord with published experimental results. The calculated beneficial effect that the longitudinal vortices have on the development of skin friction in an adverse pressure gradient demonstrates the mechanism by which vortex generators delay boundary-layer separation. It follows that the numerical model could be used to optimize arrays of air-jet vortex generators. Furthermore, the facility to quantify the interaction between the vortex and the boundary layer should also be valuable in the application of vane vortex generators, and possible even more generally.

  11. Influence of the characteristics of atmospheric boundary layer on the vertical distribution of air pollutant in China's Yangtze River Delta

    NASA Astrophysics Data System (ADS)

    Wang, Chenggang; Cao, Le

    2016-04-01

    Air pollution occurring in the atmospheric boundary layer is a kind of weather phenomenon which decreases the visibility of the atmosphere and results in poor air quality. Recently, the occurrence of the heavy air pollution events has become more frequent all over Asia, especially in Mid-Eastern China. In December 2015, the most severe air pollution in recorded history of China occurred in the regions of Yangtze River Delta and Beijing-Tianjin-Hebei. More than 10 days of severe air pollution (Air Quality Index, AQI>200) appeared in many large cities of China such as Beijing, Tianjin, Shijiazhuang and Baoding. Thus, the research and the management of the air pollution has attracted most attentions in China. In order to investigate the formation, development and dissipation of the air pollutions in China, a field campaign has been conducted between January 1, 2015 and January 28, 2015 in Yangtze River Delta of China, aiming at a intensive observation of the vertical structure of the air pollutants in the atmospheric boundary layer during the time period with heavy pollution. In this study, the observation data obtained in the field campaign mentioned above is analyzed. The characteristics of the atmospheric boundary layer and the vertical distribution of air pollutants in the city Dongshan located in the center of Lake Taihu are shown and discussed in great detail. It is indicated that the stability of the boundary layer is the strongest during the nighttime and the early morning of Dongshan. Meanwhile, the major air pollutants, PM2.5 and PM10 in the boundary layer, reach their maximum values, 177.1μg m-3 and 285μg m-3 respectively. The convective boundary layer height in the observations ranges from approximately 700m to 1100m. It is found that the major air pollutants tend to be confined in a relatively shallow boundary layer, which represents that the boundary layer height is the dominant factor for controlling the vertical distribution of the air pollutants. In

  12. Cloud layer thicknesses from a combination of surface and upper-air observations

    NASA Technical Reports Server (NTRS)

    Poore, Kirk D.; Wang, Junhong; Rossow, William B.

    1995-01-01

    Cloud layer thicknesses are derived from base and top altitudes by combining 14 years (1975-1988) of surface and upper-air observations at 63 sites in the Northern Hemisphere. Rawinsonde observations are employed to determine the locations of cloud-layer top and base by testing for dewpoint temperature depressions below some threshold value. Surface observations serve as quality checks on the rawinsonde-determined cloud properties and provide cloud amount and cloud-type information. The dataset provides layer-cloud amount, cloud type, high, middle, or low height classes, cloud-top heights, base heights and layer thicknesses, covering a range of latitudes from 0 deg to 80 deg N. All data comes from land sites: 34 are located in continental interiors, 14 are near coasts, and 15 are on islands. The uncertainties in the derived cloud properties are discussed. For clouds classified by low-, mid-, and high-top altitudes, there are strong latitudinal and seasonal variations in the layer thickness only for high clouds. High-cloud layer thickness increases with latitude and exhibits different seasonal variations in different latitude zones: in summer, high-cloud layer thickness is a maximum in the Tropics but a minimum at high latitudes. For clouds classified into three types by base altitude or into six standard morphological types, latitudinal and seasonal variations in layer thickness are very small. The thickness of the clear surface layer decreases with latitude and reaches a summer minimum in the Tropics and summer maximum at higher latitudes over land, but does not vary much over the ocean. Tropical clouds occur in three base-altitude groups and the layer thickness of each group increases linearly with top altitude. Extratropical clouds exhibit two groups, one with layer thickness proportional to their cloud-top altitude and one with small (less than or equal to 1000 m) layer thickness independent of cloud-top altitude.

  13. Dust Long-Range Transport and the Dust-Radiation Effects on the Modification of the SAL Environment

    NASA Astrophysics Data System (ADS)

    Chen, S.; Wang, S.; Waylonis, M.; Sc

    2010-12-01

    A tracer model based on the Weather Research and Forecast model was developed to simulate dust long-range transport for a dust outbreak event that occurred during July 18-20, 2005. Two numerical experiments were conducted with (ON) and without (OFF) the dust-radiation effects. Simulations were compared with the Aerosol Optical Depth (AOD) from the Moderate Resolution Imaging Spectrometer (MODIS) and results were very reasonable. The influence of dust-radiation effects on the modification of Saharan Air Layer (SAL), which can have a substantial influence on Tropical Cyclone (TC) activities over the eastern Atlantic Ocean, was also investigated. Suspended dust was able to reduce the net downward shortwave radiation by more than 300 W m-2 on the surface. The modification of temperature profiles due to dust-radiation effects resulted in the adjustment of the vertical shear. The dust-radiation effects also modified the dust distribution, which can have a feedback to the heating profile and the vertical shear.

  14. Template-directed fabrication of porous gas diffusion layer for magnesium air batteries

    NASA Astrophysics Data System (ADS)

    Xue, Yejian; Miao, He; Sun, Shanshan; Wang, Qin; Li, Shihua; Liu, Zhaoping

    2015-11-01

    The uniform micropore distribution in the gas diffusion layers (GDLs) of the air-breathing cathode is very important for the metal air batteries. In this work, the super-hydrophobic GDL with the interconnected regular pores is prepared by a facile silica template method, and then the electrochemical properties of the Mg air batteries containing these GDLs are investigated. The results indicate that the interconnected and uniform pore structure, the available water-breakout pressure and the high gas permeability coefficient of the GDL can be obtained by the application of 30% silica template. The maximum power density of the Mg air battery containing the GDL with 30% regular pores reaches 88.9 mW cm-2 which is about 1.2 times that containing the pristine GDL. Furthermore, the GDL with 30% regular pores exhibits the improved the long term hydrophobic stability.

  15. The Impact of the Saharan Air Layer on Tropical Cyclones and Tropical Climate

    NASA Astrophysics Data System (ADS)

    Dunion, J.

    2012-12-01

    Infrared and microwave satellite imagery has steadily improved our ability to detect low to mid-level dry air at tropical latitudes and in the environments of tropical disturbances. However, understanding how this dry air affects the tropical atmosphere and tropical systems remains a difficult challenge. This presentation will discuss the impacts of intraseasonal low to mid-level dry air sources (e.g. the Saharan Air Layer and mid-latitude dry air intrusions) on the mean atmospheric state of the tropical North Atlantic and present new mean soundings for this region of the world. Discussion will also include recent research that is examining how the tropical cyclone diurnal cycle and associated diurnal pulses might provide a means for helping environmental dry air influence the storm environment. Special infrared GOES imagery reveals that the timing of these diurnal pulses in the TC environment are remarkably predictable in both time and space and suggests that these features steadily propagate away from the storm each day. As these diurnal pulses reach peripheral TC radii where low to mid-level dry air is place, substantial arc clouds (100s of km in length and lasting for several hours) have been observed forming along the leading edge of the pulse. It is hypothesized that the processes leading to the formation of arc cloud events can significantly impact an AEW or TC (particularly smaller, less developed systems). Specifically, the cool, dry air associated with the convectively-driven downdrafts that form arc clouds can help stabilize the middle to lower troposphere and may even act to stabilize the boundary layer. The arc clouds themselves may also act to disrupt the storm. As they race away from the convective core region, they create low-level outflow in the quadrant/semicircle of the AEW or TC in which they form. This outflow pattern counters the typical low-level inflow that is vital for TC formation and maintenance.

  16. Air-Coupled Piezoelectric Transducers with Active Polypropylene Foam Matching Layers

    PubMed Central

    Gómez Álvarez-Arenas, Tomás E.

    2013-01-01

    This work presents the design, construction and characterization of air-coupled piezoelectric transducers using 1–3 connectivity piezocomposite disks with a stack of matching layers being the outer one an active quarter wavelength layer made of polypropylene foam ferroelectret film. This kind of material has shown a stable piezoelectric response together with a very low acoustic impedance (<0.1 MRayl). These features make them a suitable candidate for the dual use or function proposed here: impedance matching layer and active material for air-coupled transduction. The transducer centre frequency is determined by the λ/4 resonance of the polypropylene foam ferroelectret film (0.35 MHz), then, the rest of the transducer components (piezocomposite disk and passive intermediate matching layers) are all tuned to this frequency. The transducer has been tested in several working modes including pulse-echo and pitch-catch as well as wide and narrow band excitation. The performance of the proposed novel transducer is compared with that of a conventional air-coupled transducers operating in a similar frequency range. PMID:23666129

  17. Effects of air pollution on thermal structure and dispersion in an urban planetary boundary layer

    NASA Technical Reports Server (NTRS)

    Viskanta, R.; Johnson, R. O.; Bergstrom, R. W.

    1977-01-01

    The short-term effects of urbanization and air pollution on the transport processes in the urban planetary boundary layer (PBL) are studied. The investigation makes use of an unsteady two-dimensional transport model which has been developed by Viskanta et al., (1976). The model predicts pollutant concentrations and temperature in the PBL. The potential effects of urbanization and air pollution on the thermal structure in the urban PBL are considered, taking into account the results of numerical simulations modeling the St. Louis, Missouri metropolitan area.

  18. Layered perovskite oxide: a reversible air electrode for oxygen evolution/reduction in rechargeable metal-air batteries.

    PubMed

    Takeguchi, Tatsuya; Yamanaka, Toshiro; Takahashi, Hiroki; Watanabe, Hiroshi; Kuroki, Tomohiro; Nakanishi, Haruyuki; Orikasa, Yuki; Uchimoto, Yoshiharu; Takano, Hiroshi; Ohguri, Nobuaki; Matsuda, Motofumi; Murota, Tadatoshi; Uosaki, Kohei; Ueda, Wataru

    2013-07-31

    For the development of a rechargeable metal-air battery, which is expected to become one of the most widely used batteries in the future, slow kinetics of discharging and charging reactions at the air electrode, i.e., oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), respectively, are the most critical problems. Here we report that Ruddlesden-Popper-type layered perovskite, RP-LaSr3Fe3O10 (n = 3), functions as a reversible air electrode catalyst for both ORR and OER at an equilibrium potential of 1.23 V with almost no overpotentials. The function of RP-LaSr3Fe3O10 as an ORR catalyst was confirmed by using an alkaline fuel cell composed of Pd/LaSr3Fe3O10-2x(OH)2x·H2O/RP-LaSr3Fe3O10 as an open circuit voltage (OCV) of 1.23 V was obtained. RP-LaSr3Fe3O10 also catalyzed OER at an equilibrium potential of 1.23 V with almost no overpotentials. Reversible ORR and OER are achieved because of the easily removable oxygen present in RP-LaSr3Fe3O10. Thus, RP-LaSr3Fe3O10 minimizes efficiency losses caused by reactions during charging and discharging at the air electrode and can be considered to be the ORR/OER electrocatalyst for rechargeable metal-air batteries. PMID:23802735

  19. Modification of the surface layers of copper by a diffuse discharge in atmospheric pressure air

    NASA Astrophysics Data System (ADS)

    Shulepov, Mikhail A.; Erofeev, Mikhail V.; Oskomov, Konstantin V.; Tarasenko, Victor F.

    2015-12-01

    The paper presents the results of examination of copper samples exposed to a diffuse discharge initiated by a runaway electron beam in air under normal pressure. The changes in the chemical composition of the surface layers of copper caused by the action of the discharge were investigated. It has been found that the oxygen and carbon concentrations in the surface layers depend on the number of discharge pulses. The study was aimed at finding possible ways of using this type of discharge in research and industry.

  20. Airborne measurements of surface layer turbulence over the ocean during cold air outbreaks

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Shien; Yeh, Eueng-Nan

    1987-01-01

    The spectral characteristics of surface layer turbulence for the near-shore cloud street regions over the Atlantic Ocean were examined using 50-m level data of airborne measurements of atmospheric turbulence spectra above the western Atlantic Ocean during cold air outbreaks. The present study, performed for the Mesoscale Air-Sea Exchange (MASEX) experiment, extends and completes the preliminary analyses of Chou and Yeh (1987). In the inertial subrange, a near 4/3 ratio was observed between velocity spectra normal to and those along the aircraft heading. A comparison of the turbulent kinetic energy budgets with those of Wyngaard and Cote (1971) and Caughey and Wyngaard (1979) data indicates that the turbulent kinetic energy in the surface layer is dissipated less in the MASEX data than in data obtained by the previous groups.

  1. Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers

    NASA Astrophysics Data System (ADS)

    You, Jingbi; Meng, Lei; Song, Tze-Bin; Guo, Tzung-Fang; Yang, Yang (Michael); Chang, Wei-Hsuan; Hong, Ziruo; Chen, Huajun; Zhou, Huanping; Chen, Qi; Liu, Yongsheng; De Marco, Nicholas; Yang, Yang

    2016-01-01

    Lead halide perovskite solar cells have recently attracted tremendous attention because of their excellent photovoltaic efficiencies. However, the poor stability of both the perovskite material and the charge transport layers has so far prevented the fabrication of devices that can withstand sustained operation under normal conditions. Here, we report a solution-processed lead halide perovskite solar cell that has p-type NiOx and n-type ZnO nanoparticles as hole and electron transport layers, respectively, and shows improved stability against water and oxygen degradation when compared with devices with organic charge transport layers. Our cells have a p-i-n structure (glass/indium tin oxide/NiOx/perovskite/ZnO/Al), in which the ZnO layer isolates the perovskite and Al layers, thus preventing degradation. After 60 days storage in air at room temperature, our all-metal-oxide devices retain about 90% of their original efficiency, unlike control devices made with organic transport layers, which undergo a complete degradation after just 5 days. The initial power conversion efficiency of our devices is 14.6 ± 1.5%, with an uncertified maximum value of 16.1%.

  2. Improved air stability of perovskite solar cells via solution-processed metal oxide transport layers.

    PubMed

    You, Jingbi; Meng, Lei; Song, Tze-Bin; Guo, Tzung-Fang; Yang, Yang Michael; Chang, Wei-Hsuan; Hong, Ziruo; Chen, Huajun; Zhou, Huanping; Chen, Qi; Liu, Yongsheng; De Marco, Nicholas; Yang, Yang

    2016-01-01

    Lead halide perovskite solar cells have recently attracted tremendous attention because of their excellent photovoltaic efficiencies. However, the poor stability of both the perovskite material and the charge transport layers has so far prevented the fabrication of devices that can withstand sustained operation under normal conditions. Here, we report a solution-processed lead halide perovskite solar cell that has p-type NiO(x) and n-type ZnO nanoparticles as hole and electron transport layers, respectively, and shows improved stability against water and oxygen degradation when compared with devices with organic charge transport layers. Our cells have a p-i-n structure (glass/indium tin oxide/NiO(x)/perovskite/ZnO/Al), in which the ZnO layer isolates the perovskite and Al layers, thus preventing degradation. After 60 days storage in air at room temperature, our all-metal-oxide devices retain about 90% of their original efficiency, unlike control devices made with organic transport layers, which undergo a complete degradation after just 5 days. The initial power conversion efficiency of our devices is 14.6 ± 1.5%, with an uncertified maximum value of 16.1%. PMID:26457966

  3. Linear and nonlinear microrheology of lysozyme layers forming at the air-water interface.

    PubMed

    Allan, Daniel B; Firester, Daniel M; Allard, Victor P; Reich, Daniel H; Stebe, Kathleen J; Leheny, Robert L

    2014-09-28

    We report experiments studying the mechanical evolution of layers of the protein lysozyme adsorbing at the air-water interface using passive and active microrheology techniques to investigate the linear and nonlinear rheological response, respectively. Following formation of a new interface, the linear shear rheology, which we interrogate through the Brownian motion of spherical colloids at the interface, becomes viscoelastic with a complex modulus that has approximately power-law frequency dependence. The power-law exponent characterizing this frequency dependence decreases steadily with increasing layer age. Meanwhile, the nonlinear microrheology, probed via the rotational motion of magnetic nanowires at the interface, reveals a layer response characteristic of a shear-thinning power-law fluid with a flow index that decreases with age. We discuss two possible frameworks for understanding this mechanical evolution: gelation and the formation of a soft glass phase. PMID:24969505

  4. Algal layer ratios as indicators of air pollutant effects in Permelia sulcata

    USGS Publications Warehouse

    Bennett, J.P.

    2002-01-01

    Parmelia sulcata Taylor is generally believed to be fairly pollution tolerant, and consequently it is sometimes collected in urban and/or polluted localities. The condition of these specimens, however, is not always luxuriant and healthy. This study tested the hypothesis that total thallus and algal layer thickness, and the algal layer ratio would be thinner in polluted areas, thus allowing these characters to be used a indicators of air pollutant effects. Herbarium specimens were studied from 16 different localities varying in pollution level. The thallus and algal layers and ratio were not affected by year or locality of sampling, but decreased 11, 31 and 21% respectively between low and high pollution level localities. These results agreed with earlier studies using other species, but further work is needed to clarify the effects of geography and substrate on these phenomena.

  5. Magnetic septa for the Saskatchewan Accelerator Laboratory (SAL)

    SciTech Connect

    Figley, C.B. )

    1990-12-01

    A design was investigated for two magnets now in permanent use at the Saskatchewan Accelerator Laboratory (SAL). The compact septa incorporated a novel cooling technique for the thin aluminum sheets forming the coils. These magnets have operated successfully for several years. Concepts for improving the duty factor and peak field of the septa by using power modulators are considered.

  6. The role of boundary layer schemes in meteorological and air quality simulations of the Taiwan area

    NASA Astrophysics Data System (ADS)

    Cheng, Fang-Yi; Chin, Shan-Chieh; Liu, Tsun-Hsien

    2012-07-01

    Adequate air quality modeling is reliant on accurate meteorological simulations especially in the planetary boundary layer (PBL). To understand how the boundary layer processes affect the mixing and transport of air pollutants, the sensitivity of Weather Research Forecasting (WRF) model with different PBL schemes (YSU and MYJ) is utilized. Community Multiscale Air Quality (CMAQ) modeling system is performed subsequently to study the effects of the PBL physical processes on the meteorological and air quality simulations. A comparison is made of two distinct atmospheric conditions. Case 1 considers the influence of the Asian continental outflow where air pollutants carried by long-range transport (LRT) to Taiwan. The variation in ozone (O3) concentration between the two sensitivity runs is mainly caused by the PBL height difference with WRF-MYJ predicts much deeper PBL height near the frontal low-pressure region than does the WRF-YSU. Case 2 is associated with the land-sea breeze flow. In this situation O3 is locally produced from the western side of the country where major metropolitan cities and highways are located. Distinctions in O3 are caused by difference in the strength of the land-sea breeze flow between the two runs. At night the WRF-YSU predicts a weaker offshore land breeze than does the WRF-MYJ near the western coastline. During the day, the WRF-YSU predicts a stronger sea breeze near the offshore area than does the WRF-MYJ, while over the landside, the WRF-YSU predicts a lower wind speed than does the WRF-MYJ.

  7. Modelling the effects of microgravity on the permeability of air interface respiratory epithelial cell layers

    NASA Astrophysics Data System (ADS)

    dos Santos, Marlise A.; Bosquillon, Cynthia; Russomano, Thais; Sundaresan, Alamelu; Falcão, Felipe; Marriott, Christopher; Forbes, Ben

    2010-09-01

    Although it has been suggested that microgravity might affect drug absorption in vivo, drug permeability across epithelial barriers has not yet been investigated in vitro during modelled microgravity. Therefore, a cell culture/diffusion chamber was designed specifically to accommodate epithelial cell layers in a 3D-clinostat and allow epithelial permeability to be measured under microgravity conditions in vitro with minimum alteration to established cell culture techniques. Human respiratory epithelial Calu-3 cell layers were used to model the airway epithelium. Cells grown at an air interface in the diffusion chamber from day 1 or day 5 after seeding on 24-well polyester Transwell cell culture inserts developed a similar transepithelial electrical resistance (TER) to cells cultured in conventional cell culture plates. Confluent Calu-3 layers exposed to modelled microgravity in the 3D-clinostat for up to 48 h maintained their high TER. The permeability of the paracellular marker 14C-mannitol was unaffected after a 24 h rotation of the cell layers in the 3D-clinostat, but was increased 2-fold after 48 h of modelled microgravity. It was demonstrated that the culture/diffusion chamber developed is suitable for culturing epithelial cell layers and, when subjected to rotation in the 3D-clinostat, will be a valuable in vitro system in which to study the influence of microgravity on epithelial permeability and drug transport.

  8. The evolution of the boundary layer in turbulent Rayleigh-Bénard convection in air

    NASA Astrophysics Data System (ADS)

    du Puits, R.; Willert, C.

    2016-04-01

    We report measurements of the near-wall flow field in turbulent Rayleigh-Bénard convection in air (Pr = 0.7) using particle image velocimetry. The measurements were performed in a thin, rectangular sample at fixed Rayleigh number Ra = 1.45 × 1010. In particular, we focus on the evolution of the boundary layer that a single convection roll generates along its path at the lower horizontal plate. We identify three specific flow regions along this path: (i) a region of wall-normal impingement of the down flow close to one corner of the sample, (ii) a region where a shear layer with almost constant thickness evolves, and (iii) a region in which this boundary layer grows and eventually detaches from the plate surface at the opposite corner of the sample. Our measurements with a spatial resolution better than 1/500 of the total thickness of the boundary layer show that the typical velocity field as well as its statistics qualitatively varies between the three flow regions. In particular, it could be verified that the shear layer region covering about 75% of the total area of the plate is in transition to turbulence at the Rayleigh number as low as investigated in the present work.

  9. Numerical study of shock-wave/boundary layer interactions in premixed hydrogen-air hypersonic flows

    NASA Technical Reports Server (NTRS)

    Yungster, Shaye

    1990-01-01

    A computational study of shock wave/boundary layer interactions involving premixed combustible gases, and the resulting combustion processes is presented. The analysis is carried out using a new fully implicit, total variation diminishing (TVD) code developed for solving the fully coupled Reynolds-averaged Navier-Stokes equations and species continuity equations in an efficient manner. To accelerate the convergence of the basic iterative procedure, this code is combined with vector extrapolation methods. The chemical nonequilibrium processes are simulated by means of a finite-rate chemistry model for hydrogen-air combustion. Several validation test cases are presented and the results compared with experimental data or with other computational results. The code is then applied to study shock wave/boundary layer interactions in a ram accelerator configuration. Results indicate a new combustion mechanism in which a shock wave induces combustion in the boundary layer, which then propagates outwards and downstream. At higher Mach numbers, spontaneous ignition in part of the boundary layer is observed, which eventually extends along the entire boundary layer at still higher values of the Mach number.

  10. Air-sea boundary layer dynamics in the presence of mesoscale surface currents

    NASA Astrophysics Data System (ADS)

    Rooth, Claes; Xie, Lian

    1992-09-01

    In the presence of surface currents, a shear stress at the air-sea interface is induced by the surface currents. In the case of a unidirectional current, a quadratic stress law leads to a stress curl proportional to and opposing the surface current vorticity even with a uniform wind. This causes a spindown effect on the surface vorticity field at a rate proportional to the wind speed. In the steady state, or in slowly varying processes which can be treated as parametrically developing quasi-steady states, the surface-layer potential vorticity modulation causes upwelling and downwelling patterns associated with the surface-current vorticity. These effects are analyzed for an idealized jet current, and for a physical situation characteristic of a Gulf Stream boundary ring along the Florida Keys, where the induced transport patterns may be important for onshore transport of fish and spiny lobster larvae, as well as for onshore transport to the Florida Keys of general flotsam transported past them by the Gulf Stream. The spindown time scale (t*) for a 1.5-layer system is H/( ρ'cdVa) for a surface jet on the deformation radius scale (where H is the thickness of the surface layer, Va the surface wind speed, ρ' the air to water density ratio and cd the surface drag coefficient) and increases for large horizontal scales in proportion to the current width squared. For a typical wind speed of 5 m/s and a density normalized drag coefficient ρ'cd= 2 × 10-6, t* is on the order of 1 month for a 30-m surface layer. In the more general case of a stratified interior water column, the vorticity spindown directly affects only the potential vorticity of the surface layer and generally leads to subsurface velocity and vorticity maxima for mesoscale eddies and jets.

  11. Air emission into a water shear layer through porous media. Part 2: Cavitation induced pressure attenuation

    SciTech Connect

    Myer, E.C.; Marboe, R.C.

    1994-12-31

    Cavitation near the casing of a hydroturbine can lead to damage through both cavitation erosion and mechanical vibration of the casing and the associated piping. Cavitation erosion results from the collapse of cavitation bubbles on or near a surface such as the casing wall. Mechanical vibrations transmitted to the casing directly through the collapse of bubbles on the casing wall indirectly through a coupling of the acoustic pressure pulse due to a nearby collapse on the turbine blade. Air emission along the casing can reduce the intensity of the tip vortex and the gap cavitation through ventilation of the cavity. Reduction in the machinery vibration is obtained by reduction of the intensity of cavitation bubble collapse and attenuation and scattering of the radiated acoustic pressure. This requires a bubble layer which may be introduced in the vicinity of the turbine blade tips. This layer remains for some distance downstream of the blades and is effective for attenuation of tip vortex induced noise and blade surface cavitation noise. For the purpose of characterizing this bubble layer within a water pipe, the authors spanned a pipe with a two dimensional hydrofoil and emitted air through porous media (20 and 100 micron porosity sintered stainless steel) into the shear flow over the hydrofoil. This paper is limited to an investigation of the attenuation of acoustic pressure propagating to the casing rather than the reduction in acoustic source level due to collapse cushioning effects.

  12. Enhanced air pollution via aerosol-boundary layer feedback in China

    NASA Astrophysics Data System (ADS)

    Petäjä, T.; Järvi, L.; Kerminen, V.-M.; Ding, A. J.; Sun, J. N.; Nie, W.; Kujansuu, J.; Virkkula, A.; Yang, X.; Fu, C. B.; Zilitinkevich, S.; Kulmala, M.

    2016-01-01

    Severe air pollution episodes have been frequent in China during the recent years. While high emissions are the primary reason for increasing pollutant concentrations, the ultimate cause for the most severe pollution episodes has remained unclear. Here we show that a high concentration of particulate matter (PM) will enhance the stability of an urban boundary layer, which in turn decreases the boundary layer height and consequently cause further increases in PM concentrations. We estimate the strength of this positive feedback mechanism by combining a new theoretical framework with ambient observations. We show that the feedback remains moderate at fine PM concentrations lower than about 200 μg m-3, but that it becomes increasingly effective at higher PM loadings resulting from the combined effect of high surface PM emissions and massive secondary PM production within the boundary layer. Our analysis explains why air pollution episodes are particularly serious and severe in megacities and during the days when synoptic weather conditions stay constant.

  13. Enhanced air pollution via aerosol-boundary layer feedback in China

    PubMed Central

    Petäjä, T.; Järvi, L.; Kerminen, V.-M.; Ding, A.J.; Sun, J.N.; Nie, W.; Kujansuu, J.; Virkkula, A.; Yang, X.; Fu, C.B.; Zilitinkevich, S.; Kulmala, M.

    2016-01-01

    Severe air pollution episodes have been frequent in China during the recent years. While high emissions are the primary reason for increasing pollutant concentrations, the ultimate cause for the most severe pollution episodes has remained unclear. Here we show that a high concentration of particulate matter (PM) will enhance the stability of an urban boundary layer, which in turn decreases the boundary layer height and consequently cause further increases in PM concentrations. We estimate the strength of this positive feedback mechanism by combining a new theoretical framework with ambient observations. We show that the feedback remains moderate at fine PM concentrations lower than about 200 μg m−3, but that it becomes increasingly effective at higher PM loadings resulting from the combined effect of high surface PM emissions and massive secondary PM production within the boundary layer. Our analysis explains why air pollution episodes are particularly serious and severe in megacities and during the days when synoptic weather conditions stay constant. PMID:26753788

  14. Effects of an air-layer-subdivision technique on the sound transmission through a single plate.

    PubMed

    Toyoda, Masahiro; Kugo, Hajime; Shimizu, Takafumi; Takahashi, Daiji

    2008-02-01

    Many studies on the sound transmission through a single plate have been carried out theoretically and experimentally. The transmission-loss characteristics, in general, follow mass law. Therefore, increasing mass of a plate is a fundamental measure to improve the insulation performance. This method, however, has limitations and might not be a reasonable alternative in current standards. Furthermore, the transmission loss at the critical frequency of coincidence is deteriorated significantly even if the mass is rather large. In this paper, the effect of the air-layer-subdivision technique is studied in detail from the viewpoint of the sound transmission problem of a single plate. An analytical model of an infinite single plate with a subdivided layer is considered and the improvement of the transmission loss is estimated. The limitations of the technique are clarified with some parametric studies. In order to validate the predictions, an experiment was carried out. The transmission loss of a glass board with the air layer subdivided by acryl partitions was measured in the experiment. They were in good agreement with the theoretical ones near and above the coincidence. PMID:18247887

  15. Design of an air ejector for boundary-layer bleed of an acoustically treated turbofan engine inlet during ground testing

    NASA Technical Reports Server (NTRS)

    Stakolich, E. G.

    1978-01-01

    An air ejector was designed and built to remove the boundary-layer air from the inlet a turbofan engine during an acoustic ground test program. This report describes; (1) how the ejector was sized; (2) how the ejector performed; and (3) the performance of a scale model ejector built and tested to verify the design. With proper acoustic insulation, the ejector was effective in reducing boundary layer thickness in the inlet of the turbofan engine while obtaining the desired acoustic test conditions.

  16. Mixing layer height and its implications for air pollution over Beijing, China

    NASA Astrophysics Data System (ADS)

    Tang, Guiqian; Zhang, Jinqiang; Zhu, Xiaowan; Song, Tao; Münkel, Christoph; Hu, Bo; Schäfer, Klaus; Liu, Zirui; Zhang, Junke; Wang, Lili; Xin, Jinyuan; Suppan, Peter; Wang, Yuesi

    2016-03-01

    The mixing layer is an important meteorological factor that affects air pollution. In this study, the atmospheric mixing layer height (MLH) was observed in Beijing from July 2009 to December 2012 using a ceilometer. By comparison with radiosonde data, we found that the ceilometer underestimates the MLH under conditions of neutral stratification caused by strong winds, whereas it overestimates the MLH when sand-dust is crossing. Using meteorological, PM2.5, and PM10 observational data, we screened the observed MLH automatically; the ceilometer observations were fairly consistent with the radiosondes, with a correlation coefficient greater than 0.9. Further analysis indicated that the MLH is low in autumn and winter and high in spring and summer in Beijing. There is a significant correlation between the sensible heat flux and MLH, and the diurnal cycle of the MLH in summer is also affected by the circulation of mountainous plain winds. Using visibility as an index to classify the degree of air pollution, we found that the variation in the sensible heat and buoyancy term in turbulent kinetic energy (TKE) is insignificant when visibility decreases from 10 to 5 km, but the reduction of shear term in TKE is near 70 %. When visibility decreases from 5 to 1 km, the variation of the shear term in TKE is insignificant, but the decrease in the sensible heat and buoyancy term in TKE is approximately 60 %. Although the correlation between the daily variation of the MLH and visibility is very poor, the correlation between them is significantly enhanced when the relative humidity increases beyond 80 %. This indicates that humidity-related physicochemical processes is the primary source of atmospheric particles under heavy pollution and that the dissipation of atmospheric particles mainly depends on the MLH. The presented results of the atmospheric mixing layer provide useful empirical information for improving meteorological and atmospheric chemistry models and the forecasting

  17. Mathematical modelling of thin layer hot air drying of carrot pomace.

    PubMed

    Kumar, Navneet; Sarkar, B C; Sharma, H K

    2012-02-01

    Thin layer carrot pomace drying characteristics were evaluated in a laboratory scale hot air forced convective dryer. The drying experiments were carried out at 60, 65, 70 & 75 °C and at an air velocity of 0.7 m/s. Mathematical models were tested to fit drying data of carrot pomace. The whole drying process of carrot pomace took place in a falling rate period except a very short accelerating period at the beginning. The average values of effective diffusivity ranged from 2.74 × 10(-9) to 4.64 × 10(-9) m(2)/s for drying carrot pomace. The activation energy value was 23.05 kJ/mol for the whole falling rate period. PMID:23572823

  18. Atmospheric Boundary Layer Height Evolution with Lidar in Buenos Aires from 2008 to 2011

    NASA Astrophysics Data System (ADS)

    Pawelko, Ezequiel Eduardo; Salvador, Jacobo Omar; Ristori, Pablo Roberto; Pallotta, Juan Vicente; Otero, Lidia Ana; Quel, Eduardo Jaime

    2016-06-01

    The analysis of the atmospheric boundary layer top height evolution is obtained from 2008 to 2011 in Buenos Aires using the multiwavelength lidar located at CEILAP (CITEDEF-CONICET) (34°33' S; 58°30' W; 17 m asl). Algorithms recognition based on covariance wavelet transform are applied to obtain seasonal statistics. This method is being evaluated for use in the Lidar Network in Argentina and it is being deployed in Patagonia region currently. The technique operates in real time in both low and high aerosol loads and with almost no human supervision.

  19. Heat transport in the marine atmospheric boundary layer during an intense cold air outbreak

    NASA Technical Reports Server (NTRS)

    Chou, Shu-Hsien; Zimmerman, Jeffrey

    1988-01-01

    The generation of the virtual heat flux in the convective MABL associated with the January 28, 1986 intense cold air airbreak offshore of the Carolinas is studied. A technique based on the joint frequency distribution of the virtual potential temperature and vertical motion (Mahrt and Paumier, 1984) is used. The results suggest that, if buoyancy is mainly driven by the temperature flux, the physical processes for generating buoyancy flux are about the same for boundary layers over land and ocean, even with different convective regimes.

  20. Radiative and turbulent heating rates in the clear-air boundary layer

    NASA Astrophysics Data System (ADS)

    Savijärvi, Hannu

    2006-01-01

    The diurnal evolution of a clear-sky midlatitude summertime boundary layer (BL) was studied using a column model over smooth and homogeneous land, subject to weak, moderate, and strong winds. The high-resolution BL model (lowest point at 30 cm) was equipped with an adequate turbulence scheme and a narrow-band long-wave (LW) radiation scheme, the latter validated using data from the International Comparison of Radiation Codes in Climate Models (ICRCCM).In off-line ICRCCM experiments, ground emissivity ɛ < 1 led to extra LW cooling of air near the surface compared to ɛ = 1. However, much stronger LW cooling at heights of 1 3 m, and warming below 1 m, was obtained by setting the ground colder than air at screen height, a typical condition during clear nights. Conversely, a warm surface anomaly typical of sunny days leads to strong LW warming at 1 3 m, with LW cooling just above the ground. These ground temperature anomalies dominated the LW heating/cooling patterns at heights of up to 3 4 m, perhaps explaining controversies in the observed LW flux divergences close to the ground.Interactive model results indicate that the middle part of a windy clear-air nocturnal BL (NBL) is dominated by turbulent cooling, while the upper and lower NBL is dominated by LW cooling. Below about 1 m, a fourth layer is formed with LW warming and turbulent cooling, in agreement with the off-line experiments. When the surface winds fall below about 1 1.5 m s -1 LW cooling dominates in the whole NBL, except very near the surface. In these light wind conditions the Monin Obukhov theory should be revised to include radiative effects.In clear-air daytime conditions strong convective BL heating dominates over weak LW cooling except at 1 3 m heights where the cooler air absorbs the thermal emission of the hot ground. The subsequent LW warming of the superadiabatic surface layer appears to be strong enough to induce local turbulent cooling (despite the hot surface) in an 'hour glass' pattern

  1. Cold-air outbreak during GALE - Lidar observations and modeling of boundary layer dynamics

    NASA Technical Reports Server (NTRS)

    Boers, Reinout; Melfi, S. H.; Palm, Stephen P.

    1991-01-01

    Two cold-air outbreaks were studied during the Genesis of Atlantic Lows Experiment. A lidar system was operated to observe the boundary layer evolution and the development of clouds. On the first day (January 30, 1986) boundary layer rise was less than 50 percent of the value for the second day (March 2, 1986). On the first day only a thin broken cloud cover formed, while on the second day a thick solid cloud deck formed - although the average moisture content was 60 percent of that on the first day. A trajectory slab model was employed to simulate the evolution of the layer over the ocean near the east Atlantic shore. The model allows for vertical gradients in conservative variables under neutrally buoyant conditions. The primary effect of these assumptions, which are based on observed thermodynamic profiles, is to reduce cloudiness to be more in line with observations. Boundary-layer depth was reasonably well predicted as was sensible and latent heat flux.

  2. Low-speed Investigation of a Semisubmerged Air Scoop with and Without Boundary-layer Suction

    NASA Technical Reports Server (NTRS)

    Pierpont, P Kenneth; Howell, Robert R

    1951-01-01

    A preliminary low-speed investigation has been made of an air scoop submerged one-half the inlet height in a depression on the surface of a simulated fuselage. Boundary-layer suction was used on the steep approach ramp to improve the internal flow. A 6-degree-included-angle diffuser with an area ratio of 1.9:1 was located behind the inlet in the model. Most of the tests were conducted with an initial turbulent boundary layer believed to approximate that which would occur on the forward part of a fuselage. A few tests were made with a boundary layer about 2.5 times the thickness of the original boundary layer to determine the effect of moving the inlet further rearward on the fuselage. The effects of suction-slot location and slot width were determined and a few tests with area suction were made. The maximum quantity of suction flow was about 15 percent of the inlet flow at an inlet-velocity ratio of 0.6.

  3. Investigation of wintertime cold-air pools and aerosol layers in the Salt Lake Valley using a lidar ceilometer

    NASA Astrophysics Data System (ADS)

    Young, Joseph Swyler

    This thesis investigates the utility of lidar ceilometers, a type of aerosol lidar, in improving the understanding of meteorology and air quality in persistent wintertime stable boundary layers, or cold-air pools, that form in urbanized valley and basin topography. This thesis reviews the scientific literature to survey the present knowledge of persistent cold-air pools, the operating principles of lidar ceilometers, and their demonstrated utility in meteorological investigations. Lidar ceilometer data from the Persistent Cold-Air Pool Study (PCAPS) are then used with meteorological and air quality data from other in situ and remote sensing equipment to investigate cold-air pools that formed in Utah's Salt Lake Valley during the winter of 2010-2011. The lidar ceilometer is shown to accurately measure aerosol layer depth and aerosol loading, when compared to visual observations. A linear relationship is found between low-level lidar backscatter and surface particulate measurements. Convective boundary layer lidar analysis techniques applied to cold-air pool ceilometer profiles can detect useful layer characteristics. Fine-scale waves are observed and analyzed within the aerosol layer, with emphasis on Kelvin-Helmholz waves. Ceilometer aerosol backscatter profiles are analyzed to quantify and describe mixing processes in persistent cold-air pools. Overlays of other remote and in-situ observations are combined with ceilometer particle backscatter to describe specific events during PCAPS. This analysis describes the relationship between the aerosol layer and the valley inversion as well as interactions with large-scale meteorology. The ceilometer observations of hydrometers are used to quantify cloudiness and precipitation during the project, observing that 50% of hours when a PCAP was present had clouds or precipitation below 5 km above ground level (AGL). Then, combining an objective technique for determining hourly aerosol layer depths and correcting this

  4. Sal-Site: research resources for the Mexican axolotl.

    PubMed

    Baddar, Nour W Al Haj; Woodcock, M Ryan; Khatri, Shivam; Kump, D Kevin; Voss, S Randal

    2015-01-01

    Sal-Site serves axolotl research efforts by providing Web access to genomic data and information, and living stocks that are reared and made available by the Ambystoma Genetic Stock Center (AGSC). In this chapter, we detail how investigators can search for genes of interest among Sal-Site resources to identify orthologous nucleotide and protein-coding sequences, determine genome positions within the Ambystoma meiotic map, and obtain estimates of gene expression. In the near future, additional genomic resources will be made available for the axolotl, including a listing of genes that are partially or wholly contained within Bacterial Artificial Chromosome (BAC) vectors, a prioritized collection of deeply sequenced BAC clones, chromosome-specific assemblies of genomic DNA, and transgenic axolotls that are engineered using TALENs and CRISPRs. Also, services provided by the AGSC will be expanded to include microinjection of user constructs into single cell embryos and distribution of axolotl tissues, DNA, and RNA. In conclusion, Sal-Site is a useful resource that generates, shares, and evolves Ambystoma associated information and databases to serve research and education. PMID:25740497

  5. Silver-Copper Nanoalloy Catalyst Layer for Bifunctional Air Electrodes in Alkaline Media.

    PubMed

    Wu, Xiaoqiang; Chen, Fuyi; Jin, Yachao; Zhang, Nan; Johnston, Roy L

    2015-08-19

    A carbon-free and binder-free catalyst layer composed of a Ag-Cu nanoalloy on Ni foam was used as the air cathode in a zinc-air battery for the first time. The Ag-Cu catalyst was prepared using pulsed laser deposition. The structures of the catalysts were found to consist of crystalline Ag-Cu nanoalloy particles with an average size of 2.58 nm embedded in amorphous Cu films. As observed in the X-ray photoelectron spectra, the Ag 3d core levels shifted to higher binding energies, whereas the Cu 2p core levels shifted to lower binding energies, indicating alloying of the silver and copper. Rotating disk electrode measurements indicated that the oxygen reduction reaction (ORR) proceeded through a four-electron pathway on the Ag50Cu50 and Ag90Cu10 nanoalloy catalysts in alkaline solution. Moreover, the catalytic activity of Ag50Cu50 in the ORR is more efficient than that of Ag90Cu10. By performing charge and discharge cycling measurements, the Ag50Cu50 catalyst layer was confirmed to have a maximum power density of approximately 86.3 mW cm(-2) and an acceptable cell voltage at 0.863 V for current densities up to 100 mA cm(-2) in primary zinc-air batteries. In addition, a round-trip efficiency of approximately 50% at a current density of 20 mA cm(-2) was also obtained in the test. PMID:26200807

  6. Effect of air velocity on kinetics of thin layer carrot pomace drying.

    PubMed

    Kumar, N; Sarkar, B C; Sharma, H K

    2011-10-01

    Carrot pomace is a by-product obtained during carrot juice processing. Thin layer carrot pomace drying was performed in a laboratory scale hot air forced convective dryer. The drying experiments were carried out at the air velocity of 0.5, 0.7 and 1.0 m/s at air temperatures from 60 to 75 °C. It was observed that whole drying process of carrot pomace took place in a falling rate period except a very short accelerating period at the beginning. Mathematical models were tested to fit drying data of carrot pomace. The best fit model was observed on the basis of R², Chi-square and RMSE values. R² values for all the selected models were above 0.9783. The average values of effective diffusivity ranged from 2.61 × 10(-9) to 3.64 × 10(-9) m²/s. PMID:21954311

  7. 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.

  8. Mixing layer height measurements determines influence of meteorology on air pollutant concentrations in urban area

    NASA Astrophysics Data System (ADS)

    Schäfer, Klaus; Blumenstock, Thomas; Bonn, Boris; Gerwig, Holger; Hase, Frank; Münkel, Christoph; Nothard, Rainer; von Schneidemesser, Erika

    2015-10-01

    Mixing layer height (MLH) is a key parameter to determine the influence of meteorological parameters upon air pollutants such as trace gas species and particulate concentrations near the surface. Meteorology, and MLH as a key parameter, affect the budget of emission source strengths, deposition, and accumulation. However, greater possibilities for the application of MLH data have been identified in recent years. Here, the results of measurements in Berlin in 2014 are shown and discussed. The concentrations of NO, NO2, O3, CO, PM1, PM2.5, PM10 and about 70 volatile organic compounds (anthropogenic and biogenic of origin) as well as particle size distributions and contributions of SOA and soot species to PM were measured at the urban background station of the Berlin air quality network (BLUME) in Nansenstr./Framstr., Berlin-Neukölln. A Vaisala ceilometer CL51, which is a commercial mini-lidar system, was applied at that site to detect the layers of the lower atmosphere in real time. Special software for these ceilometers with MATLAB provided routine retrievals of MLH from vertical profiles of laser backscatter data. Five portable Bruker EM27/SUN FTIR spectrometers were set up around Berlin to detect column averaged abundances of CO2 and CH4 by solar absorption spectrometry. Correlation analyses were used to show the coupling of temporal variations of trace gas compounds and PM with MLH. Significant influences of MLH upon NO, NO2, PM10, PM2.5, PM1 and toluene (marker for traffic emissions) concentrations as well as particle number concentrations in the size modes 70 - 100 nm, 100 - 200 nm and 200 - 500 nm on the basis of averaged diurnal courses were found. Further, MLH was taken as important auxiliary information about the development of the boundary layer during each day of observations, which was required for the proper estimation of CO2 and CH4 source strengths from Berlin on the basis of atmospheric column density measurements.

  9. Effect on a shock wave boundary layer interaction of air jet vortex generators

    NASA Astrophysics Data System (ADS)

    Souverein, L. J.; Debiève, J.-F.

    2012-01-01

    The effect of upstream injection by means of continuous Air Jet Vortex Generators (AJVGs) on a shock wave turbulent boundary layer interaction is experimentally investigated. The baseline interaction is of the impinging type, with a flow deflection angle of 9.5° , a Mach number Me = 2.3, and a momentum thickness based Reynolds number of 5,000. Considered are the effects of the AJVGs on the upstream boundary layer flow topology and on the spatial and dynamical characteristics of the interaction. To this aim, Stereoscopic Particle Image Velocimetry has been employed, in addition to hot-wire anemometry (HWA) for the investigation of the dynamical characteristics of the reflected shock. It is shown that the AJVGs significantly modify the three-dimensionality of the upstream boundary layer. Overall, the AJVGs cause a reduction of the separation bubble length and height. In addition, the energetic frequency range of the reflected shock is increased by approximately 50%, which is in qualitative agreement with the smaller separation bubble size.

  10. Vehicle cabin cooling system for capturing and exhausting heated boundary layer air from inner surfaces of solar heated windows

    DOEpatents

    Farrington, Robert B.; Anderson, Ren

    2001-01-01

    The cabin cooling system includes a cooling duct positioned proximate and above upper edges of one or more windows of a vehicle to exhaust hot air as the air is heated by inner surfaces of the windows and forms thin boundary layers of heated air adjacent the heated windows. The cabin cooling system includes at least one fan to draw the hot air into the cooling duct at a flow rate that captures the hot air in the boundary layer without capturing a significant portion of the cooler cabin interior air and to discharge the hot air at a point outside the vehicle cabin, such as the vehicle trunk. In a preferred embodiment, the cooling duct has a cross-sectional area that gradually increases from a distal point to a proximal point to the fan inlet to develop a substantially uniform pressure drop along the length of the cooling duct. Correspondingly, this cross-sectional configuration develops a uniform suction pressure and uniform flow rate at the upper edge of the window to capture the hot air in the boundary layer adjacent each window.

  11. Air, aqueous and thermal stabilities of Ce3+ ions in cerium oxide nanoparticle layers with substrates.

    PubMed

    Naganuma, Tamaki; Traversa, Enrico

    2014-06-21

    Abundant oxygen vacancies coexisting with Ce(3+) ions in fluorite cerium oxide nanoparticles (CNPs) have the potential to enhance catalytic ability, but the ratio of unstable Ce(3+) ions in CNPs is typically low. Our recent work, however, demonstrated that the abundant Ce(3+) ions created in cerium oxide nanoparticle layers (CNPLs) by Ar ion irradiation were stable in air at room temperature. Ce valence states in CNPs correlate with the catalytic ability that involves redox reactions between Ce(3+) and Ce(4+) ions in given application environments (e.g. high temperature in carbon monoxide gas conversion and immersion conditions in biomedical applications). To better understand the mechanism by which Ce(3+) ions achieve stability in CNPLs, we examined (i) extra-long air-stability, (ii) thermal stability up to 500 °C, and (iii) aqueous stability of Ce(3+) ions in water, buffer solution and cell culture medium. It is noteworthy that air-stability of Ce(3+) ions in CNPLs persisted for more than 1 year. Thermal stability results showed that oxidation of Ce(3+) to Ce(4+) occurred at 350 °C in air. Highly concentrated Ce(3+) ions in ultra-thin CNPLs slowly oxidized in water within 1 day, but stability was improved in the cell culture medium. Ce(3+) stability of CNPLs immersed in the medium was associated with phosphorus adsorption on the Ce(3+) sites. This study also illuminates the potential interaction mechanisms of stable Ce(3+) ions in CNPLs. These findings could be utilized to understand catalytic mechanisms of CNPs with abundant oxygen vacancies in their application environments. PMID:24812662

  12. Doped lanthanum nickelates with a layered perovskite structure as bifunctional cathode catalysts for rechargeable metal-air batteries.

    PubMed

    Jung, Kyu-Nam; Jung, Jong-Hyuk; Im, Won Bin; Yoon, Sukeun; Shin, Kyung-Hee; Lee, Jong-Won

    2013-10-23

    Rechargeable metal-air batteries have attracted a great interest in recent years because of their high energy density. The critical challenges facing these technologies include the sluggish kinetics of the oxygen reduction-evolution reactions on a cathode (air electrode). Here, we report doped lanthanum nickelates (La2NiO4) with a layered perovskite structure that serve as efficient bifunctional electrocatalysts for oxygen reduction and evolution in an aqueous alkaline electrolyte. Rechargeable lithium-air and zinc-air batteries assembled with these catalysts exhibit remarkably reduced discharge-charge voltage gaps (improved round-trip efficiency) as well as high stability during cycling. PMID:24053465

  13. Organization and sequence of the SalI restriction-modification system.

    PubMed

    Rodicio, M R; Quinton-Jager, T; Moran, L S; Slatko, B E; Wilson, G G

    1994-12-30

    The organization and nucleotide (nt) sequences were determined for the genes encoding the SalI restriction and modification (R-M) system (recognition sequence 5'-GTCGAC-3') from Streptomyces albus G. The system comprises two genes, salIR, coding for the restriction endonuclease (ENase, R.SalI; probably 315 amino acids (aa), a predicted M(r) of 35,305; product, G'TCGAC) and salIM, coding for the methyltransferase (MTase, M.SalI; probably 587 aa, a predicted M(r) of 64,943; product, GTCGm6AC). The genes are adjacent, they have the same orientation, and they occur in the order salIR then salIM. R.SalI contains a putative magnesium-binding motif similar to those at the active sites of R.EcoRI and R.EcoRV, but otherwise it bears little aa sequence similarity to other ENases. M.SalI is a member of the m6A gamma class of MTases. In aa sequence it resembles M.AccI, another m6A gamma-MTase whose recognition sequence includes the SalI recognition sequence as a subset. PMID:7828868

  14. 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 ...

  15. The evolution of the clear air convective layer revealed by surface-based remote sensors

    NASA Technical Reports Server (NTRS)

    Noonkester, V. R.

    1976-01-01

    Results are reported for simultaneous observations of the growth and decay of the clear-air convective mixing layer near a coastline, which were made with an FM-CW radar, a high-power narrow-beam S-band radar, and an acoustic echo sounder. The main purpose of this study was to determine the relationship between the rise rate of the convective depth and the lapse rate of temperature, particularly in the morning hours. The results indicate that the three remote sensors can provide excellent mutually supporting data on the convective depth. It is found that this depth is well behaved during the day and that its rise rate varies roughly linearly with the inverse square root of the temperature lapse rate during the morning. The data suggest that some models concerning the rise rate require modification, since these models imply that the surface heat flux would have to be unreasonably large to produce the observed relationship.

  16. Numerical simulation of air-blast atomization of a liquid layer

    NASA Astrophysics Data System (ADS)

    Agbaglah, G. Gilou; McCaslin, Jeremy; Desjardins, Olivier

    2015-11-01

    Numerical simulations of a planar co-flowing air/water airblast atomization is performed using an in-house multiphase Navier-Stokes solver based on a semi-lagrangian geometric Volume of Fluid (VOF) method to track the position of the interface. This solver conserves mass and momentum exactly within each phase. Excellent agreement with recent experiments is obtained when comparing physical quantities, such as the liquid cone length, the maximum wave frequency and the spatial growth rate of the primary instability. A full three dimensional simulation is used to analyze the turbulence in the gas phase. The gas layer is laminar close to the injector and becomes turbulent at downstream positions. The transition to the turbulence is shown to increase first as an exponential function of the downstream positions and then reach a statistically stable regime where the liquid wave crests expand in a thin sheet which breaks into secondary droplets.

  17. Sensing and signaling of oxidative stress in chloroplasts by inactivation of the SAL1 phosphoadenosine phosphatase.

    PubMed

    Chan, Kai Xun; Mabbitt, Peter D; Phua, Su Yin; Mueller, Jonathan W; Nisar, Nazia; Gigolashvili, Tamara; Stroeher, Elke; Grassl, Julia; Arlt, Wiebke; Estavillo, Gonzalo M; Jackson, Colin J; Pogson, Barry J

    2016-08-01

    Intracellular signaling during oxidative stress is complex, with organelle-to-nucleus retrograde communication pathways ill-defined or incomplete. Here we identify the 3'-phosphoadenosine 5'-phosphate (PAP) phosphatase SAL1 as a previously unidentified and conserved oxidative stress sensor in plant chloroplasts. Arabidopsis thaliana SAL1 (AtSAL1) senses changes in photosynthetic redox poise, hydrogen peroxide, and superoxide concentrations in chloroplasts via redox regulatory mechanisms. AtSAL1 phosphatase activity is suppressed by dimerization, intramolecular disulfide formation, and glutathionylation, allowing accumulation of its substrate, PAP, a chloroplast stress retrograde signal that regulates expression of plastid redox associated nuclear genes (PRANGs). This redox regulation of SAL1 for activation of chloroplast signaling is conserved in the plant kingdom, and the plant protein has evolved enhanced redox sensitivity compared with its yeast ortholog. Our results indicate that in addition to sulfur metabolism, SAL1 orthologs have evolved secondary functions in oxidative stress sensing in the plant kingdom. PMID:27432987

  18. Transport of polluted boundary layer air from the Po Valley to high-alpine sites

    NASA Astrophysics Data System (ADS)

    Seibert, Petra; Kromp-kolb, Helga; Kasper, Anne; Kalina, Michael; Puxbaum, Hans; Jost, Dieter T.; Schwikowski, Margit; Baltensperger, Urs

    Within the EUROTRAC subproject ALPTRAC the occurrence of reactive trace species at high-alpine sites was investigated. As a part of these studies, the transport of boundary layer air from the Po Valley, which is one potential major source region for air pollution in the Alps, to the high-mountain sites Sonnblick (3106 m) in Austria and Jungfraujoch (3579 m) in Switzerland was studied. A case study based on isentropic trajectories derived from a fine-mesh analysis showed the potential of such transports to cause substantial peaks in the aerosol concentration at Sonnblick. However, on a climatological basis the Po Valley does not seem to cause higher-than-average concentrations of species such as SO 2, SO 2-4, NH +4 and NO -3. Its contribution was estimated to be about 15% in summer and much less in winter. Indications of orographically induced, subgrid vertical transports were found which are important for the interpretation of data from pollution monitoring programmes at high-alpine sites.

  19. Mathematical modelling of thin layer hot air drying of apricot with combined heat and power dryer.

    PubMed

    Faal, Saeed; Tavakoli, Teymor; Ghobadian, Barat

    2015-05-01

    In this study thermal energy of an engine was used to dry apricot. For this purpose, experiments were conducted on thin layer drying apricot with combined heat and power dryer, in a laboratory dryer. The drying experiments were carried out for four levels of engine output power (25 %, 50 %, 75 % and full load), producing temperatures of 50, 60, 70, and 80 ° C in drying chamber respectively. The air velocity in drying chamber was about 0.5 ± 0.05 m/s. Different mathematical models were evaluated to predict the behavior of apricot drying in a combined heat and power dryer. Conventional statistical equations namely modeling efficiency (EF), Root mean square error (RMSE) and chi-square (χ2) were also used to determine the most suitable model. Assessments indicated that the Logarithmic model considering the values of EF = 0.998746, χ 2 = 0.000120 and RMSE = 0.004772, shows the best treatment of drying apricot with combined heat and power dryer among eleven models were used in this study. The average values of effective diffusivity ranged 1.6260 × 10(-9) to 4.3612 × 10(-9) m2/s for drying apricot at air temperatures between 50 and 80 °C and at the air flow rate of 0.5 ± 0.05 m/s; the values of Deff increased with the increase of drying temperature the effective diffusivities in the second falling rate period were about eight times greater than that in the first falling rate period. PMID:25892795

  20. Turbulent Boundary Layer on a Finely Perforated Surface Under Conditions of Air Injection at the Expense of External Flow Resources

    NASA Astrophysics Data System (ADS)

    Kornilov, V. I.; Boiko, A. V.; Kavun, I. N.

    2015-11-01

    The characteristics of an incompressible turbulent boundary layer on a flat plate with air blown in though a finely perforated surface from an external confined flow through an input device, located on the "idle" side of the plate, have been investigated experimentally and numerically. A stable decrease in the local values of the coefficient of surface friction along the plate length that attains 85% at the end of the perforated portion is shown. The experimental and calculated data obtained point to the possibility of modeling, under earth conditions, the process of controlling a turbulent boundary layer with air injection by using the resources of an external confined flow.

  1. Weather-type stratified verification of quantitative precipitation forecasts with the feature based technique SAL

    NASA Astrophysics Data System (ADS)

    Zimmer, M.; Wernli, H.

    2009-09-01

    Recently, a new generation of NWP models has been developed with a horizontal grid spacing that allows the explicit simulation of deep convection. In this study, we investigate whether this new category of models produces better precipitation forecasts than the previous model generation with parameterized deep convection - and in particular, we like to investigate whether the differences are more pronounced during certain weather types. Quantitative precipitation forecasts (QPF) from 20 deterministic forecast models from the MAP D-PHASE experiment are analysed with the feature-based verification technique SAL during the DOP (Demonstration Observation Period; June till November 2007). SAL contains three independent components that consider aspects of the structure (S), amplitude (A) and location (L) of the precipitation field in a pre-defined domain, in this study the German part of the COPS area. The weather type classification is based upon an objective front analysis tool recently developed at the ETH Zurich. This tool identifies fronts as regions with intense horizontal gradients in the equivalent potential temperature field at 850 hPa. It allows to distinguish between quasi-stationary fronts and propagating warm and cold fronts. We will use the objectively identified fronts to classify precipitation events either as pre-frontal, frontal or post-frontal, and in the absence of any significant frontal structures and for warm surface conditions as air-mass convection. The observational data set used for the verification has an hourly time resolution and is based upon a disaggregation technique, which combines the high temporal resolution of radar data with the fairly high accuracy of the amount of precipitation obtained from rain gauge measurements. All precipitation data sets have been transformed onto the same grid with a horizontal grid space of 7 km. Evaluations of daily accumulated QPFs show that most of the very high resolution models (i.e. those without

  2. Improved light output power of LEDs with embedded air voids structure and SiO2 current blocking layer

    NASA Astrophysics Data System (ADS)

    Zhou, Shengjun; Yuan, Shu; Liu, Sheng; Ding, Han

    2014-06-01

    GaN-based light-emitting diodes (LEDs) with an embedded air voids structure and a SiO2 current blocking layer (CBL) was fabricated and investigated. The air voids structure was formed between cone-shaped patterned sapphire substrate and GaN epitaxial layer by combining laser scribing with H3PO4-based hot chemical etching. The air voids embedded high power LED showed 8.9% higher light output power due to a strong light reflection and redirection at the interface between GaN and air voids, which could increase the top light extraction of the high power LED. Compared to the air voids embedded high power LED, the light output power of the high power LED by integrating air voids structure with SiO2 CBL was 9.1% higher than that of the air voids embedded LED without SiO2 CBL. It was also found that the simulation results agree well with the experimental results.

  3. Gravity-base SALS (single anchor leg system) at Tazerka

    SciTech Connect

    Not Available

    1983-10-01

    A gravity-base single anchor leg system (SALS) delivers crude oil from subsea wells to a converted tanker for Shell Tunirex, as operator of a joint venture. The SALS features a manifold chamber and high-pressure swivels which permit varied operations to be performed remotely and in complete safety. The system is designed to accommodate up to 8 wells; inject water into a maximum of 3 wells and produce from the remaining 5; provide gas lift, if needed; shut in the system at the wellhead, at the manifold, or on the tanker; permit switching from any one of 6 high-pressure swivels to another in case of seal failure; permit quick replacement of entire swivel assembly if overhaul needed; withstand 100-yr environmental conditions; use its built-in restoration mechanics to return the riser to a vertical position if environmental forces cause tanker movement; be self-installable with only light support craft; and be recoverable, for further use elsewhere after field depletion.

  4. Stereographic Visualization of the Influence of Stratospheric Air on Ozone Layers Encountered During TRACE-P

    NASA Astrophysics Data System (ADS)

    Holdzkom, J.; Avery, M.; Hoell, J.; Newell, R.; Fuelberg, H.; Hu, Y.; Browell, E.

    2002-12-01

    The NASA TRAnsport and Chemical Evolution over the Pacific (TRACE-P) aircraft-based measurement campaign was conducted over the northwestern Pacific Basin during March-April, 2001. The broad objectives of determining the chemical composition and evolution of Asian outflow over the western Pacific during the spring time period, and understanding the ensemble of processes that control this evolution. A defining characteristic of the TRACE-P mission was the integration of aircraft, satellite, and ground-based studies, with a particularly strong coupling between the experimental investigations and modeling studies. While the resulting suite of observational data and model results provide a rich source for unraveling the various processes impacting the composition of Asian outflow, it also presents a challenge for efficient visualization of results from the various data sets. A promising approach for visual analysis of such multi-parametered data sets is through software called the Virtual Global Explorer and Observatory (vGeo). The vGeo software facilitates the merging of data objects into a single realistic 3-D stereographic environment in which the user can view, navigate, and interact with the data. Several outflow events encountered during TRACE-P will be presented in a 3-D stereographic world using vGeo. The 3-D visualization merges TRACE-P chemical measurements, meteorological fields, and air mass trajectories into a virtual world that provides a more intuitive synthesis of the combined chemical and dynamical fields. This presentation will focus on upper tropospheric layers of elevated ozone measured during TRACE-P flights in the vicinity of the Japan Jet. Representations of potential temperature, potential vorticity and vertical velocity from the European Center for Medium-Range Weather Forecasting (ECMWF) analysis, combined with coupled air mass trajectories suggest regions of enhanced ozone encountered by the aircraft that were significantly influenced by the

  5. On Modeling Air/Space-Borne Radar Returns in the Melting Layer

    NASA Technical Reports Server (NTRS)

    Liao, Liang; Meneghini, Robert

    2005-01-01

    The bright band is the enhanced radar echo associated with the melting of hydrometeors in stratiform rain where the melting process usually occurs below 0 C isotherm over a distance of about 500m. To simulate this radar signature, a scattering model of melting snow is proposed in which the fractional water content is prescribed as a function of the radius of a spherical mixed- phase particle consisting of air, ice and water. The model is based on the observation that melting starts at the surface of the particle and then gradually develops towards the center. To compute the scattering parameters of a non-uniform melting particle, the particle is modeled as a sphere represented by a collection of 64(exp 3) cubic cells of identical size where the probability of water at any cell is prescribed as a function of the radius. The internal field of the particle, used for deriving the effective dielectric constant, is computed by the Conjugate Gradient and Fast Fourier Transform (CGFFT) numerical methods. To make computations of the scattering parameters more efficient, a multi-layer stratified-sphere scattering model is introduced after demonstrating that the scattering parameters of the non-uniformly melting particle can be accurately reproduced by the stratified sphere. In conjunction with a melting layer model that describes the melting fractions and fall velocities of hydrometeors as a function of the distance from the 0 C isotherm, the stratified-sphere model is used to simulate the radar bright band profiles. These simulated profiles are shown to compare well with measurements from the Precipitation Radar (PR) aboard the Tropical Rainfall Measuring Mission (TRMM) satellite and a dual-wavelength airborne radar. The results suggest that the proposed model of a melting snow particle may be useful in studying the characteristics of the bright-band in particular and mixed- phase hydrometeors in general.

  6. Development of carbon free diffusion layer for activated carbon air cathode of microbial fuel cells.

    PubMed

    Yang, Wulin; Kim, Kyoung-Yeol; Logan, Bruce E

    2015-12-01

    The fabrication of activated carbon air cathodes for larger-scale microbial fuel cells requires a diffusion layer (DL) that is highly resistant to water leakage, oxygen permeable, and made using inexpensive materials. A hydrophobic polyvinylidene fluoride (PVDF) membrane synthesized using a simple phase inversion process was examined as a low cost ($0.9/m(2)), carbon-free DL that prevented water leakage at high pressure heads compared to a polytetrafluoroethylene/carbon black DL ($11/m(2)). The power density produced with a PVDF (20%, w/v) DL membrane of 1400±7mW/m(2) was similar to that obtained using a wipe DL [cloth coated with poly(dimethylsiloxane)]. Water head tolerance reached 1.9m (∼19kPa) with no mesh supporter, and 2.1m (∼21kPa, maximum testing pressure) with a mesh supporter, compared to 0.2±0.05m for the wipe DL. The elimination of carbon black from the DL greatly simplified the fabrication procedure and further reduced overall cathode costs. PMID:26342345

  7. Analysis of sterol and other components present in unsaponifiable matters of mahua, sal and mango kernel oil.

    PubMed

    Dhara, Rupali; Bhattacharyya, Dipak K; Ghosh, Mahua

    2010-01-01

    The amount and characterization of phytosterol and other minor components present in three Indian minor seed oils, mahua (Madhuca latifolia), sal (Shorea robusta) and mango kernel (Mangifera indica), have been done. Theses oils have shown commercial importance as cocoa-butter substitutes because of their high symmetrical triglycerides content. The conventional thin layer chromatography (TLC), gas chromatography (GC) & gas chromatography-mass spectroscopy (GC-MS) techniques were used to characterize the components and the high performance thin layer chromatography (HPTLC) technique was used to quantify the each group of components. The experimental data showed that the all the three oils are rich in sterol content and among all the sterols, beta-sitosterol occupies the highest amount. Sal oil contains appreciable amount of cardenolides, gitoxigenin. Tocopherol is present only in mahua oil and oleyl alcohol is present in mango kernel oil. Hydrocarbon, squalene, is present in all the three oils. The characterization of these minor components will help to detect the presence of the particular oil in specific formulations and to assess its stability as well as nutritional quality of the specific oil. PMID:20299763

  8. Morphological affinities of the Sal'a 1 frontal bone.

    PubMed

    Sládek, Vladimír; Trinkaus, Erik; Sefcáková, Alena; Halouzka, Rudolf

    2002-12-01

    The human frontal bone from Sal'a, Slovak Republic, has previously entered into discussions of the morphological patterns of Central European Neandertals and the origins of early modern humans in that region. A morphological reassessment of its supraorbital region and a morphometric analysis of its overall proportions indicate that it falls well within expected ranges of variation of Late Pleistocene Neandertals and is separate from European earlier Upper Paleolithic early modern human crania. It is similar to the Qafzeh-Skhul sample in some metrical and supraorbital robusticity measures, but it contrasts with them in mid-sagittal curvature and supraorbital torus morphology. In the context of its probable oxygen isotope stage 5 age based on inferred biostratigraphic associations, it should not be employed directly for arguments relating to the emergence of modern humans in Central Europe. PMID:12473484

  9. SalSA: A Teraton UHE Neutrino Detector

    SciTech Connect

    Reil, Kevin; /SLAC

    2006-04-19

    The observed spectrum of ultra-high energy cosmic rays virtually guarantees the presence of ultra-high energy neutrinos due to their interaction with the cosmic microwave background. Unlike cosmic rays, each of these neutrinos will point back directly to its source and will arrive at the Earth unattenuated, from sources perhaps as distant as z = 20. The neutrino telescopes currently under construction, should discover a handful of these events, probably too few for detailed study. This paper describes how an array of VHF and UHF antennas embedded in a large salt dome, SalSA (Salt dome Shower Array) promises to yield a teraton detector (> 500 km{sup 3 sr}) for contained neutrino events with energies above 10{sup 17} eV. Our simulations show that such a detector may observe several hundreds of these neutrinos over its lifetime with excellent angular resolution providing source locations.

  10. A novel method for air drying aloe leaf slices by covering with filter papers as a shrink-proof layer.

    PubMed

    Kim, S A; Baek, J H; Lee, S J; Choi, S Y; Hur, W; Lee, S Y

    2009-01-01

    To prevent the shrinkage of aloe vera slices during air drying, a method utilizing a shrink-proof layer was developed. The sample was configured of whole leaf aloe slices, where 1 side or both sides were covered with filter papers as shrink-proof layers. After air drying by varying the air temperature and the slice thickness, the drying characteristics, as well as several quality factors of the dried aloe vera leaf slices, were analyzed. In the simulation of the drying curves, the modified Page model showed the best fitness, representing a diffusion-controlled drying mechanism. Nonetheless, there was a trace of a constant-rate drying period in the samples dried by the method. Shrinkage was greatly reduced, and the rehydration ratios increased by approximately 50%. Scanning electron microscopic analysis revealed that the surface structure of original fibrous form was well sustained. FT-IR characteristics showed that the dried samples could sustain aloe polysaccharide acetylation. Furthermore, the functional properties of the dried slices including water holding capacity, swelling, and fat absorption capability were improved, and polysaccharide retention levels increased by 20% to 30%. Therefore, we concluded that application of shrink-proof layers on aloe slices provides a novel way to overcome the shrinkage problems commonly found in air drying, thereby improving their functional properties with less cost. Practical Application: This research article demonstrates a novel air drying method using shrink-proof layers to prevent the shrinkage of aloe slices. We analyzed extensively the characteristics of shrinkage mechanism and physical properties of aloe flesh gels in this drying system. We concluded that this method can be a beneficial means to retain the functional properties of dried aloe, and a potential alternative to freeze drying, which is still costly. PMID:20492108

  11. Ozone in the Boundary Layer air over the Arctic Ocean: Measurements During the TARA Expedition.

    NASA Astrophysics Data System (ADS)

    Bottenheim, J. W.; Netcheva, S.; Morin, S.; Gascard, J.; Weber, M.; de Marliave, C.; Trouble, R.

    2007-12-01

    It is now well established that after sunrise in polar regions, the atmospheric boundary layer experiences episodes where dramatic loss of ozone can be observed. Virtually all measurements in this respect have been made at coastal observatories on land, but there is strong evidence to surmise that such episodes originate over the frozen ocean. Satellite measurements (GOME, SCIAMACHY, OMI) invariably indicate large areas over the ocean with increased concentrations of BrO which can be interpreted as a smoking gun for ozone depletion processes, but no systematic in-situ measurements of ozone do exist to corroborate the satellite data. The TARA expedition (www.taraexpeditions.org) (IPY project # 238) has enabled us for the first time to make long term ozone measurements in the surface air over the Arctic Ocean, and we report here the first results. As expected ozone was found to be stable at approx. 35 ± 5 nmol~mol-1 during the winter, but shortly after local sunrise in mid March, large depletions of ozone were observed which lasted until well into June. A particularly long episode (> 15 days) of virtually no ozone (mole fraction below or near 1 nmol~mol-1) was experienced during late April. 10-day back trajectories were calculated in an attempt to obtain more insight into the potential origin of the depletion episodes. To place the TARA ozone data into context we will compare the data with land based and satellite observations in 2007 when they become available, as well as the limited record of previous observations made from ice islands. Taking all evidence together it is plausible to speculate that large areas over the Arctic Ocean are devoid of ozone in the atmospheric boundary layer in the first months after polar sunrise, and that if anything, this will increase in the coming years. We speculate what the implications might be. This work is a contribution to IPY project #038 (OASIS, Ocean Atmosphere Sea-Ice and Snow interactions in polar regions), sponsored by

  12. Microwave and Electro-optical Transmission Experiments in the air-sea Boundary Layer

    NASA Astrophysics Data System (ADS)

    Anderson, K. D.

    2002-12-01

    Microwave and electro-optical signal propagation over a wind-roughened sea is strongly dependent on signal interaction with the sea surface, the mean profiles of pressure (P), humidity (Q), temperature (T), wind (U) and their turbulent fluctuations (p, q, t, u). Yet, within the marine surface layer, these mechanisms are not sufficiently understood nor has satisfactory data been taken to validate propagation models, especially under conditions of high seas, high winds, and large surface gradients of Q and T. To address this deficiency, the Rough Evaporation Duct (RED) experiment was designed to provide first data for validation of meteorological, microwave, and electro-optical models in the marine surface layer for rough surface conditions including the effects of surface waves. The RED experiment was conducted offshore of the Hawaiian Island of Oahu in late summer, mid-August to mid-September, of 2001. R/P FLIP, moored about 10 km off of the NE coast of Oahu, hosted the primary meteorological sensor suites and served as a terminus for the propagation links. There were eleven scientists and engineers aboard R/P FLIP who installed instruments measuring mean and turbulent meteorological quantities, sea wave heights, directions, and kinematics, upward and downward radiance, near surface bubble generation, atmospheric particle size distributions, laser probing of the atmosphere, and sources for both microwave and electro-optic signals. In addition to R/P FLIP, two land sites were instrumented with microwave and electro-optic receivers and meteorological sensors, two buoys were deployed, a small boat was instrumented, and two aircraft flew various tracks to sense both sea and atmospheric conditions. In all, more than 25 people from four countries, six universities, and four government agencies were directly involved with the RED experiment. While the overall outcome of the RED experiment is positive, we had a number of major and minor problems with the outfitting

  13. Boundary-Layer Development and Low-level Baroclinicity during High-Latitude Cold-Air Outbreaks: A Simple Model

    NASA Astrophysics Data System (ADS)

    Chechin, Dmitry G.; Lüpkes, Christof

    2016-08-01

    A new quasi-analytical mixed-layer model is formulated describing the evolution of the convective atmospheric boundary layer (ABL) during cold-air outbreaks (CAO) over polar oceans downstream of the marginal sea-ice zones. The new model is superior to previous ones since it predicts not only temperature and mixed-layer height but also the height-averaged horizontal wind components. Results of the mixed-layer model are compared with dropsonde and aircraft observations carried out during several CAOs over the Fram Strait and also with results of a 3D non-hydrostatic (NH3D) model. It is shown that the mixed-layer model reproduces well the observed ABL height, temperature, low-level baroclinicity and its influence on the ABL wind speed. The mixed-layer model underestimates the observed ABL temperature only by about 10 %, most likely due to the neglect of condensation and subsidence. The comparison of the mixed-layer and NH3D model results shows good agreement with respect to wind speed including the formation of wind-speed maxima close to the ice edge. It is concluded that baroclinicity within the ABL governs the structure of the wind field while the baroclinicity above the ABL is important in reproducing the wind speed. It is shown that the baroclinicity in the ABL is strongest close to the ice edge and slowly decays further downwind. Analytical solutions demonstrate that the e -folding distance of this decay is the same as for the decay of the difference between the surface temperature of open water and of the mixed-layer temperature. This distance characterizing cold-air mass transformation ranges from 450 to 850 km for high-latitude CAOs.

  14. A novel Whole Air Sample Profiler (WASP) for the quantification of volatile organic compounds in the boundary layer

    SciTech Connect

    Mak, J. E.; Su, L.; Guenther, Alex B.; Karl, Thomas G.

    2013-10-16

    The emission and fate of reactive VOCs is of inherent interest to those studying chemical biosphere-atmosphere interactions. In-canopy VOC observations are obtainable using tower-based samplers, but the lack of suitable sampling systems for the full boundary 5 layer has limited the data characterizing the vertical structure of such gases above the canopy height and still in the boundary layer. This is the important region where many reactive VOCs are oxidized or otherwise removed. Here we describe an airborne sampling system designed to collect a vertical profile of air into a 3/800 OD tube 150m in length. The inlet ram air pressure is used to flow sampled air through the 10 tube, which results in a varying flow rate based on aircraft speed and altitude. Since aircraft velocity decreases during ascent, it is necessary to account for the variable flow rate into the tube. This is accomplished using a reference gas that is pulsed into the air stream so that the precise altitude of the collected air can be reconstructed post-collection. The pulsed injections are also used to determine any significant effect 15 from diffusion/mixing within the sampling tube, either during collection or subsequent extraction for gas analysis. This system has been successfully deployed, and we show some measured vertical profiles of isoprene and its oxidation products methacrolein and methyl vinyl ketone from a mixed canopy near Columbia, Missouri.

  15. Ice Nucleating Particle Properties in the Saharan Air Layer Close to the Dust Source

    NASA Astrophysics Data System (ADS)

    Boose, Y.; Garcia, I. M.; Rodríguez, S.; Linke, C.; Schnaiter, M.; Nickovic, S.; Lohmann, U.; Kanji, Z. A.; Sierau, B.

    2015-12-01

    In August 2013 and 2014 measurements of ice nucleating particle (INP) concentrations, aerosol particle size distributions, chemistry and fluorescence were conducted at the Izaña Atmospheric Observatory located at 2373 m asl on Tenerife, west off the African shore. During summer, the observatory is frequently within the Saharan Air Layer and thus often exposed to dust. Absolute INP concentrations and activated fractions at T=-40 to -15°C and RHi=100-150 % were measured. In this study, we discuss the in-situ measured INP properties with respect to changes in the chemical composition, the biological content, the source regions as well as transport pathways and thus aging processes of the dust aerosol. For the first time, ice crystal residues were also analyzed with regard to biological content by means of their autofluorescence signal close to a major dust source region. Airborne dust samples were collected with a cyclone for additional offline analysis in the laboratory under similar conditions as in the field. Both, in-situ and offline dust samples were chemically characterized using single-particle mass spectrometry. The DREAM8 dust model extended with dust mineral fractions was run to simulate meteorological and dust aerosol conditions for ice nucleation. Results show that the background aerosol at Izaña was dominated by carbonaceous particles, which were hardly ice-active under the investigated conditions. When Saharan dust was present, INP concentrations increased by up to two orders of magnitude even at water subsaturated conditions at T≤-25°C. Differences in the ice-activated fraction were found between different dust periods which seem to be linked to variations in the aerosol chemical composition (dust mixed with changing fractions of sea salt and differences in the dust aerosol itself). Furthermore, two biomass burning events in 2014 were identified which led to very low INP concentrations under the investigated temperature and relative humidity

  16. Interactions between Oceanic Saharan Air Layer and African Easterly Jet- African Easterly Waves System

    NASA Astrophysics Data System (ADS)

    Hosseinpour, F.; Wilcox, E. M.

    2013-12-01

    Aerosols have robust influences on multi-scale climatic systems and variability. Non-linear aerosol-cloud-climate interactions depend on many parameters such as aerosol features, regional atmospheric dynamics and variability. Although there are remarkable modeling studies indicating that aerosols induce robust modifications in cloud properties, circulations and the hydrological cycle, many of the physical and dynamical processes involving in these complex interactions between aerosols and Earth's system are still poorly understood. Better understanding the contribution of aerosols with atmospheric phenomena and their transient changes are crucial for efforts to evaluate climate predictions by next generation climate models. This study provides strong evidence of mechanistic relationships between perturbations of the oceanic Saharan air layer (OSAL) and anomalies of atmospheric circulations over the eastern tropical Atlantic/Africa. These relationships are characterized using an ensemble of daily datasets including the Modern-Era Retrospective Analysis for Research and Applications (MERRA), the Moderate Resolution Imaging Spectro-radiometer (MODIS), and the Sea-viewing Wide Field-of-View Sensor (SeaWIFS) for the boreal summer season. The study is motivated by previous results suggesting that oceanic dust-induced large-scale to meso-scale climatic adjustments. Our hypothesis is that perturbations in OSAL significantly interact with regional climate variability through African Easterly Jet- African Easterly Waves (AEJ-AEW) system. Passive/ active phases of AEWs in the northern and southern-track wave packets are associated with dipole patterns of thermal/dynamical anomalies correlated with perturbations of aerosol optical depth (AOD) in OSAL. Enhanced (suppressed) dust AOD in OSAL are significantly correlated with convective re-circulation within subsidence region of Hadley cell as well as robust mid-level dipole vorticity disturbances downstream of the AEJ core

  17. Vertical structure of boundary layer convection during cold-air outbreaks at Barrow, Alaska

    NASA Astrophysics Data System (ADS)

    Wang, Yonggang; Geerts, Bart; Chen, Yaosheng

    2016-01-01

    Boundary layer convection (BLC) is common over high-latitude oceans and adjacent coastal regions when a cold airmass becomes exposed to a sufficient fetch of open water. The vertical structure of mixed-phase BLC clouds and precipitation is examined using the Atmospheric Radiation Measurement Program data set collected at the North Slope of Alaska (NSA) site at Barrow, Alaska. BLC may occur at this location in autumn, when cold air masses originating at higher latitudes advect southward over the still ice-free coastal waters north of Alaska. This study identifies such BLC and documents its occurrence and characteristics. Instruments used for this study include profiling Ka band radars, a depolarization backscatter profiling lidar, a scanning X band radar, a microwave radiometer, a ceilometer, surface meteorological probes, and radiosondes. Six criteria are applied to objectively identify the BLC events, using data collected between 2004 and 2013. BLC episodes are relatively common at the NSA site, but almost exclusively in the month of October, and most episodes are relatively short, less than 10 h in duration. Liquid water is commonly found in these mixed-phase BLC clouds, with a typical liquid water path of 150 g/m2, and snowfall rates average ~3 mm h-1 (water equivalent), in some cases over 10 mm h-1, notwithstanding the low cloud echo tops (~1.0-1.5 km). In one rather weak but persistent episode fall speed estimates derived from the profiling Ka band radar indicates the presence of rimed particles, confirming the convective nature of this precipitation.

  18. The marine boundary layer - new findings from the Östergarnsholm air-sea interaction site

    NASA Astrophysics Data System (ADS)

    Smedman, A.; Högström, U.

    2003-04-01

    From studies at the air-sea interaction site Östergarnsholm, a coherent picture of how waves interact with the atmosphere is now beginning to emerge. It is clear that the surface of the ocean behaves similar to that of a solid surface with regard to the turbulence structure in the surface layer only for conditions of pure wind sea, i.e. during the phase when waves are in the process of being built up by increasing wind. At that stage of wave development, the dominant waves are short and move slowly relative to the wind. Then the drag coefficient CDN is a function only of the wave age, expressed as u*/c_p (where u* is friction velocity and c_p is the phase velocity of the dominant waves). The relation obtained by us is identical to the corresponding expression obtained from several recent ocean experiments, Drennan et al. (2000). As soon as the wave field develops behind the "pure wind sea" stage towards conditions where relatively long waves start to gain importance, inter-actions caused by these longer waves are felt in the atmosphere at our lowest turbulence measuring height, 10 m. For example it is demonstrated that the logarithmic wind law is not valid in near-neutral conditions except when pure wind sea conditions prevail and, further that for mixed seas and swell conditions, CDN is a function not only of the wave age parameter u*/c_p but also of a second wave parameter E_1/E_2, which is a measure of the proportion of energy of relatively long waves to short waves. The neutral Stanton Number, CHN, is found to follow predictions from surface-renewal theory quite well for unstable conditions up to a wind speed of about 10 ms-1. For higher wind speed CHN increases with increasing wind speed and the interpretation is made that spray is the cause of the increase.

  19. On the '-1' scaling of air temperature spectra in atmospheric surface layer flows

    NASA Astrophysics Data System (ADS)

    Li, D.; Katul, G. G.; Gentine, P.

    2015-12-01

    The spectral properties of scalar turbulence at high wavenumbers have been extensively studied in turbulent flows, and existing theories explaining the k-5/3 scaling within the inertial subrange appear satisfactory at high Reynolds numbers. Equivalent theories for the low wavenumber range have been comparatively lacking because boundary conditions prohibit attainment of such universal behavior. A number of atmospheric surface layer (ASL) experiments reported a k-1 scaling in air temperature spectra ETT(k) at low wavenumbers but other experiments did not. Here, the occurrence of a k-1 scaling in ETT(k) in an idealized ASL flow across a wide range of atmospheric stability regimes is investigated theoretically and experimentally. Experiments reveal a k-1 scaling persisted across different atmospheric stability parameter values (ζ) ranging from mildly unstable to mildly stable conditions (-0.1< ζ < 0.2). As instability increases, the k-1 scaling vanishes. Based on a combined spectral and co-spectral budget models and upon using a Heisenberg eddy viscosity as a closure to the spectral flux transfer term, conditions promoting a k-1 scaling are identified. Existence of a k-1 scaling is shown to be primarily linked to an imbalance between the production and dissipation rates of half the temperature variance. The role of the imbalance between the production and dissipation rates of half the temperature variance in controlling the existence of a '-1' scaling suggests that the '-1' scaling in ETT(k) does not necessarily concur with the '-1' scaling in the spectra of longitudinal velocity Euu(k). This finding explains why some ASL experiments reported k-1 in Euu(k) but not ETT(k). It also differs from prior arguments derived from directional-dimensional analysis that lead to simultaneous k-1 scaling in Euu(k) and ETT(k) at low wavenumbers in a neutral ASL.

  20. 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.

  1. A forecasting system using the parabolic equation: Application to surface-to-air propagation in the presence of elevated layers

    NASA Astrophysics Data System (ADS)

    Craig, K. H.; Levy, M. F.

    1989-09-01

    The parabolic equation approach to clear-air propagation modeling overcomes many of the difficulties associated with ray and mode theory methods. A parabolic equation model was implemented on a PC based system using a transputer to carry out the computationally intensive numerical integrations. The model was used from VHF to millimetric frequencies and applied to evaporation duct and elevated duct problems. The latter are important for surface-to-air propagation and were difficult to solve because of the complicated structure of the layers. A case study of an elevated duct caused by anticyclonic subsidence shows the importance of up-to-date meteorological data from a wide geographical area. A full-wave calculation of the wideband properties of the propagation channel illustrates the possibilities opened up by the new model. The frequency selective effects can be large, and are sensitive to the small-scale structure of the ducting layers.

  2. Reference dosimetry at the Australian Synchrotron's imaging and medical beamline using free-air ionization chamber measurements and theoretical predictions of air kerma rate and half value layer

    SciTech Connect

    Crosbie, Jeffrey C.; Rogers, Peter A. W.; Stevenson, Andrew W.; Hall, Christopher J.; Lye, Jessica E.; Nordstroem, Terese; Midgley, Stewart M.; Lewis, Robert A.

    2013-06-15

    Purpose: Novel, preclinical radiotherapy modalities are being developed at synchrotrons around the world, most notably stereotactic synchrotron radiation therapy and microbeam radiotherapy at the European Synchrotron Radiation Facility in Grenoble, France. The imaging and medical beamline (IMBL) at the Australian Synchrotron has recently become available for preclinical radiotherapy and imaging research with clinical trials, a distinct possibility in the coming years. The aim of this present study was to accurately characterize the synchrotron-generated x-ray beam for the purposes of air kerma-based absolute dosimetry. Methods: The authors used a theoretical model of the energy spectrum from the wiggler source and validated this model by comparing the transmission through copper absorbers (0.1-3.0 mm) against real measurements conducted at the beamline. The authors used a low energy free air ionization chamber (LEFAC) from the Australian Radiation Protection and Nuclear Safety Agency and a commercially available free air chamber (ADC-105) for the measurements. The dimensions of these two chambers are different from one another requiring careful consideration of correction factors. Results: Measured and calculated half value layer (HVL) and air kerma rates differed by less than 3% for the LEFAC when the ion chamber readings were corrected for electron energy loss and ion recombination. The agreement between measured and predicted air kerma rates was less satisfactory for the ADC-105 chamber, however. The LEFAC and ADC measurements produced a first half value layer of 0.405 {+-} 0.015 and 0.412 {+-} 0.016 mm Cu, respectively, compared to the theoretical prediction of 0.427 {+-} 0.012 mm Cu. The theoretical model based upon a spectrum calculator derived a mean beam energy of 61.4 keV with a first half value layer of approximately 30 mm in water. Conclusions: The authors showed in this study their ability to verify the predicted air kerma rate and x-ray attenuation

  3. Thin layer convective air drying of wild edible plant (Allium roseum) leaves: experimental kinetics, modeling and quality.

    PubMed

    Ben Haj Said, Leila; Najjaa, Hanen; Farhat, Abdelhamid; Neffati, Mohamed; Bellagha, Sihem

    2015-06-01

    The present study deals with the valorization of an edible spontaneous plant of the Tunisian arid areas: Allium roseum. This plant is traditionally used for therapeutic and culinary uses. Thin-layer drying behavior of Allium roseum leaves was investigated at 40, 50 and 60 °C drying air temperatures and 1 and l.5 m/s air velocity, in a convective dryer. The increase in air temperature significantly affected the moisture loss and reduced the drying time while air velocity was an insignificant factor during drying of Allium roseum leaves. Five models selected from the literature were found to satisfactorily describe drying kinetics of Allium roseum leaves for all tested drying conditions. Drying data were analyzed to obtain moisture diffusivity values. During the falling rate-drying period, moisture transfer from Allium roseum leaves was described by applying the Fick's diffusion model. Moisture diffusivity varied from 2.55 × 10(-12) to 8.83 × 10(-12) m(2)/s and increased with air temperature. Activation energy during convective drying was calculated using an exponential expression based on Arrhenius equation and ranged between 46.80 and 52.68 kJ/mol. All sulfur compounds detected in the fresh leaves were detected in the dried leaves. Convective air drying preserved the sulfur compounds potential formation. PMID:26028758

  4. High-Reynolds-number turbulent-boundary-layer wall pressure fluctuations with skin-friction reduction by air injection.

    PubMed

    Winkel, Eric S; Elbing, Brian R; Ceccio, Steven L; Perlin, Marc; Dowling, David R

    2008-05-01

    The hydrodynamic pressure fluctuations that occur on the solid surface beneath a turbulent boundary layer are a common source of flow noise. This paper reports multipoint surface pressure fluctuation measurements in water beneath a high-Reynolds-number turbulent boundary layer with wall injection of air to reduce skin-friction drag. The experiments were conducted in the U.S. Navy's Large Cavitation Channel on a 12.9-m-long, 3.05-m-wide hydrodynamically smooth flat plate at freestream speeds up to 20 ms and downstream-distance-based Reynolds numbers exceeding 200 x 10(6). Air was injected from one of two spanwise slots through flush-mounted porous stainless steel frits (approximately 40 microm mean pore diameter) at volume flow rates from 17.8 to 142.5 l/s per meter span. The two injectors were located 1.32 and 9.78 m from the model's leading edge and spanned the center 87% of the test model. Surface pressure measurements were made with 16 flush-mounted transducers in an "L-shaped" array located 10.7 m from the plate's leading edge. When compared to no-injection conditions, the observed wall-pressure variance was reduced by as much as 87% with air injection. In addition, air injection altered the inferred convection speed of pressure fluctuation sources and the streamwise coherence of pressure fluctuations. PMID:18529171

  5. cycloSal-PMEA and cycloAmb-PMEA: potentially new phosphonate prodrugs based on the cycloSal-pronucleotide approach.

    PubMed

    Meier, Chris; Görbig, Ulf; Müller, Christian; Balzarini, Jan

    2005-12-15

    Two new classes of lipophilic prodrugs of the antiviral active phosphonate 9-[2-phosphonomethoxyethyl]adenine (PMEA 1) have been prepared and were studied with regard to their hydrolysis properties and biological activity. A first series of compounds was prepared on the basis of the cycloSal nucleotide approach. Because of the surprisingly low hydrolysis stability of these cycloSal-PMEA derivatives, more stable derivatives have to be developed. Instead of using salicyl alcohol, in cycloAmb-PMEA derivatives 2-aminobenzyl alcohols were attached to PMEA 1. The latter compounds showed a considerably higher stability compared to the cycloSal counterparts. Stability studies revealed that all lipophilic prodrugs delivered PMEA selectively by chemical means. All compounds proved to be noninhibiting to acetyl- and butyrylcholinesterase, and some of the phosphonate diesters were found to be more active against HIV compared to the parent PMEA. PMID:16335932

  6. Cay Sal Bank, Bahamas: a partially drowned carbonate platform

    SciTech Connect

    Hine, A.C.; Steinmetz, J.C.

    1983-03-01

    Recent high resolution seismic profiling, sediment sampling, scuba observations, and Landsat imagery show that Cay Sal Bank (CSB) has very limited reef development, no active sand shoals (ooid or otherwise), few islands, a thin to nonexistent sedimentary cover, and a relatively deep margin (20 to 30 m (66 to 100 ft)) and shelf lagoon system (10 to 20 m (33 to 66 ft)). Windward margins (facing north and east) along CSB are generally deep, rocky, sediment barren terraces supporting limited, low relief, relict(.) reefs. Seismic and grab sample data from the deep (200 to 500 m (600 to 1650 ft)) slopes seaward of the leeward margins show a thin, discontinuous unit of periplatform, shallow-water derived Halimeda, molluscan, nonskeletal sands. The apparent immature development of normal bank-top processes and facies and the absence of key modern depositional environments on CSB may be related to the rate at which this platform was submerged. The relatively rapid flooding of CSB provided little time for the shallow depositional environments to start up. The continued rapid rate of rise after drowning, plus offbank sediment transport and the export of chilled waters (formed during winter), prevented the resulting facies from catching up. Consequently, CSB appears to be partially drowned, particularly when compared to the other, healthier, rimmed Bahamian platforms. Other investigators have pointed out that drowned carbonate banks are very common in the ancient and that these features potentially provide excellent stratigraphic traps for hydrocarbons.

  7. Mitigating methane emissions and air intrusion in heterogeneous landfills with a high permeability layer.

    PubMed

    Jung, Yoojin; Imhoff, Paul T; Augenstein, Don; Yazdani, Ramin

    2011-05-01

    Spatially variable refuse gas permeability and landfill gas (LFG) generation rate, cracking of the soil cover, and reduced refuse gas permeability because of liquid addition can all affect CH(4) collection efficiency when intermediate landfill covers are installed. A new gas collection system that includes a near-surface high permeability layer beneath the landfill cover was evaluated for enhancing capture of LFG and mitigating CH(4) emissions. Simulations of gas transport in two-dimensional domains demonstrated that the permeable layer reduces CH(4) emissions up to a factor of 2 for particular spatially variable gas permeability fields. When individual macrocracks formed in the cover soil and the permeable layer was absent, CH(4) emissions increased to as much as 24% of the total CH(4) generated, double the emissions when the permeable layer was installed. CH(4) oxidation in the cover soil was also much more uniform when the permeable layer was present: local percentages of CH(4) oxidized varied between 94% and 100% across the soil cover with the permeable layer, but ranged from 10% to 100% without this layer for some test cases. However, the permeable layer had a minor effect on CH(4) emissions and CH(4) oxidation in the cover soil when the ratio of the gas permeability of the cover soil to the mean refuse gas permeability ≤ 0.05. The modeling approach employed in this study may be used to assess the utility of other LFG collection systems and management practices. PMID:20880688

  8. EEG characterization of audiogenic seizures in the hamster strain GASH:Sal.

    PubMed

    Carballosa-Gonzalez, Melissa M; Muñoz, Luis J; López-Alburquerque, Tomás; Pardal-Fernández, José Manuel; Nava, Eduardo; de Cabo, Carlos; Sancho, Consuelo; López, Dolores E

    2013-10-01

    The study was performed to characterize GASH:SAL audiogenic seizures as true epileptic activity based on electroencephalographic markers acquired with a wireless implanted radiotelemetry system. We analyzed cortical EEG patterns synchronized with video recordings of convulsive behavior of the GASH:Sal hamster following an acoustic stimulus. All GASH:Sal presented archetypal motor symptoms comparable to current animal models of generalized tonic-clonic epilepsy. Seizures consisted of an initial bout of wild running, followed by opisthotonus, tonic-clonic convulsions, tonic limb extension, and terminated in postictal depression. EEG patterns correlated with behavior and displayed phase appropriate spike-wave complexes, low-amplitude desynchronized activity, and high frequency large-amplitude peaks. Our results confirm that electroencephalographic profiles of the audiogenic seizures of the hamster GASH:Sal are parallel to EEG patterns of other animal models of generalized tonic-clonic seizures. Therefore, this animal may serve as an appropriate model for epilepsy research. PMID:23916142

  9. Comparison of the Antibacterial Properties of Phage Endolysins SAL-1 and LysK▿

    PubMed Central

    Jun, Soo Youn; Jung, Gi Mo; Son, Jee-Soo; Yoon, Seong Jun; Choi, Yun-Jaie; Kang, Sang Hyeon

    2011-01-01

    In spite of the high degree of amino acid sequence similarity between the newly discovered phage endolysin SAL-1 and the phage endolysin LysK, SAL-1 has an approximately 2-fold-lower MIC against several Staphylococcus aureus strains and higher bacterial cell-wall-hydrolyzing activity than LysK. The amino acid residue change contributing the most to this enhanced enzymatic activity is a change from glutamic acid to glutamine at the 114th residue. PMID:21263051

  10. Theoretical and numerical study of air layer drag reduction in two-phase Couette-Poiseuille flow

    NASA Astrophysics Data System (ADS)

    Kim, Dokyun; Moin, Parviz

    2008-11-01

    The objective of the present study is to predict and understand the air layer drag reduction (ALDR) phenomenon. Recent experiments (Elbing et al. 2008) have shown net drag reductions if air is injected beyond a critical rate next to the wall. The analysis is performed on a two-phase Couette-Poiseuille flow configuration, which mimics the far downstream region of boundary layer flow on a flat plate. Both theoretical and numerical approaches are employed to investigate the stability and mechanisms of ALDR. The linear stability of air-liquid interface is investigated by solving the Orr-Sommerfeld equations. From the stability analysis, the stability of the interface is reduced as the liquid free-stream velocity, Froude number and velocity gradients at the interface are increased, while the stability is enhanced as the gas flow rate and surface tension are increased. The Critical gas flow rates from stability theory are compared with experimental results, showing good agreement. Direct numerical simulations with a Refiend Level Set Grid technique has been performed to investigate the evolution of the interface, the turbulence interaction and nonlinear mechanisms of ALDR. It is observed that the Weber number has significant impact on the characteristics of the interface development.

  11. Photoswitching the mechanical properties in Langmuir layers of semifluorinated alkyl-azobenzenes at the air-water interface.

    PubMed

    Theodoratou, Antigoni; Jonas, Ulrich; Loppinet, Benoit; Geue, Thomas; Stangenberg, René; Li, Dan; Berger, Rüdiger; Vlassopoulos, Dimitris

    2015-11-21

    Semifluorinated alkyl-azobenzene derivatives (SFAB) can form stable Langmuir layers at the air-water interface. These systems combine the amphiphobic character of semifluorinated alkyl units as structure-directing motifs with photochromic behavior based on the well-known reversible cis-trans isomerization upon irradiation with UV and visible light. Herein, we report our investigations of the structural and dynamic tunability of these SFAB layers at the air-water interface in response to an external light stimulus. The monolayer structures and properties of [4-(heptadecafluorooctyl)phenyl](4-octylphenyl)diazene (F8-azo-H8) and bis(4-octylphenyl)diazene (H8-azo-H8) were studied by neutron reflectivity, surface pressure-area isotherms with compression-expansion cycles, and interfacial rheology. We find that UV irradiation reversibly influences the packing behavior of the azobenzene molecules and interpret this as a transition from organized layer structures with the main axis of the molecule vertically oriented in the trans form to random packing of the cis isomer. Interestingly, this trans-cis isomerization leads to an increase in surface pressure, which is accompanied by a decrease in viscoelastic moduli. These results suggest ways of tailoring the properties of responsive fluid interfaces. PMID:26451399

  12. Sum-Frequency Generation Spectroscopy for Studying Organic Layers at Water-Air Interfaces: Microlayer Monitoring and Surface Reactivity

    NASA Astrophysics Data System (ADS)

    Laß, Kristian; Kleber, Joscha; Bange, Hermann; Friedrichs, Gernot

    2015-04-01

    The sea surface microlayer, according to commonly accepted terminology, comprises the topmost millimetre of the oceanic water column. It is often enriched with organic matter and is directly influenced by sunlight exposure and gas exchange with the atmosphere, hence making it a place for active biochemistry and photochemistry as well as for heterogeneous reactions. In addition, surface active material either is formed or accumulates directly at the air-water interface and gives rise to very thin layers, sometimes down to monomolecular thickness. This "sea surface nanolayer" determines the viscoelastic properties of the seawater surface and thus may impact the turbulent air-sea gas exchange rates. To this effect, this small scale layer presumably plays an important role for large scale changes of atmospheric trace gas concentrations (e.g., by modulating the ocean carbon sink characteristics) with possible implications for coupled climate models. To date, detailed knowledge about the composition, structure, and reactivity of the sea surface nanolayer is still scarce. Due to its small vertical dimension and the small amount of material, this surfactant layer is very difficult to separate and analyse. A way out is the application of second-order nonlinear optical methods, which make a direct surface-specific and background-free detection of this interfacial layer possible. In recent years, we have introduced the use of vibrational sum frequency generation (VSFG) spectroscopy to gain insight into natural and artificial organic monolayers at the air-water interface. In this contribution, the application of VSFG spectroscopy for the analysis of the sea surface nanolayer will be illustrated. Resulting spectra are interpreted in terms of layer composition and surfactant classes, in particular with respect to carbohydrate-containing molecules such as glycolipids. The partitioning of the detected surfactants into soluble and non-soluble ("wet" and "dry") surfactants will be

  13. Characterisation of SalRAB a Salicylic Acid Inducible Positively Regulated Efflux System of Rhizobium leguminosarum bv viciae 3841

    PubMed Central

    Tett, Adrian J.; Karunakaran, Ramakrishnan; Poole, Philip S.

    2014-01-01

    Salicylic acid is an important signalling molecule in plant-microbe defence and symbiosis. We analysed the transcriptional responses of the nitrogen fixing plant symbiont, Rhizobium leguminosarum bv viciae 3841 to salicylic acid. Two MFS-type multicomponent efflux systems were induced in response to salicylic acid, rmrAB and the hitherto undescribed system salRAB. Based on sequence similarity salA and salB encode a membrane fusion and inner membrane protein respectively. salAB are positively regulated by the LysR regulator SalR. Disruption of salA significantly increased the sensitivity of the mutant to salicylic acid, while disruption of rmrA did not. A salA/rmrA double mutation did not have increased sensitivity relative to the salA mutant. Pea plants nodulated by salA or rmrA strains did not have altered nodule number or nitrogen fixation rates, consistent with weak expression of salA in the rhizosphere and in nodule bacteria. However, BLAST analysis revealed seventeen putative efflux systems in Rlv3841 and several of these were highly differentially expressed during rhizosphere colonisation, host infection and bacteroid differentiation. This suggests they have an integral role in symbiosis with host plants. PMID:25133394

  14. SalB inactivation modulates culture supernatant exoproteins and affects autolysis and viability in Enterococcus faecalis OG1RF.

    PubMed

    Shankar, Jayendra; Walker, Rachel G; Wilkinson, Mark C; Ward, Deborah; Horsburgh, Malcolm J

    2012-07-01

    The culture supernatant fraction of an Enterococcus faecalis gelE mutant of strain OG1RF contained elevated levels of the secreted antigen SalB. Using differential fluorescence gel electrophoresis (DIGE) the salB mutant was shown to possess a unique complement of exoproteins. Differentially abundant exoproteins were identified using matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) mass spectrometry. Stress-related proteins including DnaK, Dps family protein, SOD, and NADH peroxidase were present in greater quantity in the OG1RF salB mutant culture supernatant. Moreover, several proteins involved in cell wall synthesis and cell division, including d-Ala-d-Lac ligase and EzrA, were present in reduced quantity in OG1RF salB relative to the parent strain. The salB mutant displayed reduced viability and anomalous cell division, and these phenotypes were exacerbated in a gelE salB double mutant. An epistatic relationship between gelE and salB was not identified with respect to increased autolysis and cell morphological changes observed in the salB mutant. SalB was purified as a six-histidine-tagged protein to investigate peptidoglycan hydrolytic activity; however, activity was not evident. High-pressure liquid chromatography (HPLC) analysis of reduced muropeptides from peptidoglycan digested with mutanolysin revealed that the salB mutant and OG1RF were indistinguishable. PMID:22563054

  15. Computational Study of Surface Tension and Wall Adhesion Effects on an Oil Film Flow Underneath an Air Boundary Layer

    NASA Technical Reports Server (NTRS)

    Celic, Alan; Zilliac, Gregory G.

    1998-01-01

    The fringe-imaging skin friction (FISF) technique, which was originally developed by D. J. Monson and G. G. Mateer at Ames Research Center and recently extended to 3-D flows, is the most accurate skin friction measurement technique currently available. The principle of this technique is that the skin friction at a point on an aerodynamic surface can be determined by measuring the time-rate-of-change of the thickness of an oil drop placed on the surface under the influence of the external air boundary layer. Lubrication theory is used to relate the oil-patch thickness variation to shear stress. The uncertainty of FISF measurements is estimated to be as low as 4 percent, yet little is known about the effects of surface tension and wall adhesion forces on the measured results. A modified version of the free-surface Navier-Stokes solver RIPPLE, developed at Los Alamos National Laboratories, was used to compute the time development of an oil drop on a surface under a simulated air boundary layer. RIPPLE uses the volume of fluid method to track the surface and the continuum surface force approach to model surface tension and wall adhesion effects. The development of an oil drop, over a time period of approximately 4 seconds, was studied. Under the influence of shear imposed by an air boundary layer, the computed profile of the drop rapidly changes from its initial circular-arc shape to a wedge-like shape. Comparison of the time-varying oil-thickness distributions computed using RIPPLE and also computed using a greatly simplified numerical model of an oil drop equation which does not include surface tension and wall adhesion effects) was used to evaluate the effects of surface tension on FISF measurement results. The effects of surface tension were found to be small but not necessarily negligible in some cases.

  16. Electroburning of few-layer graphene flakes, epitaxial graphene, and turbostratic graphene discs in air and under vacuum

    PubMed Central

    Richter, Nils; Convertino, Domenica; Coletti, Camilla; Balestro, Franck; Wernsdorfer, Wolfgang; Kläui, Mathias; Affronte, Marco

    2015-01-01

    Summary Graphene-based electrodes are very promising for molecular electronics and spintronics. Here we report a systematic characterization of the electroburning (EB) process, leading to the formation of nanometer-spaced gaps, on different types of few-layer graphene (namely mechanically exfoliated graphene on SiO2, graphene epitaxially grown on the C-face of SiC and turbostratic graphene discs deposited on SiO2) under air and vacuum conditions. The EB process is found to depend on both the graphene type and on the ambient conditions. For the mechanically exfoliated graphene, performing EB under vacuum leads to a higher yield of nanometer-gap formation than working in air. Conversely, for graphene on SiC the EB process is not successful under vacuum. Finally, the EB is possible with turbostratic graphene discs only after the creation of a constriction in the sample using lithographic patterning. PMID:25821711

  17. Photo-degradation in air of the active layer components in a thiophene-quinoxaline copolymer:fullerene solar cell.

    PubMed

    Hansson, Rickard; Lindqvist, Camilla; Ericsson, Leif K E; Opitz, Andreas; Wang, Ergang; Moons, Ellen

    2016-04-28

    We have studied the photo-degradation in air of a blend of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and poly[2,3-bis-(3-octyloxyphenyl)quinoxaline-5,8-diyl-alt-thiophene-2,5-diyl] (TQ1), and how the photo-degradation affects the solar cell performance. Using near-edge X-ray absorption fine structure (NEXAFS) spectroscopy, changes to the electronic structure of TQ1 and PCBM caused by illumination in ambient air are investigated and compared between the pristine materials and the blend. The NEXAFS spectra show that the unoccupied molecular orbitals of TQ1 are not significantly changed by the exposure of pristine TQ1 to light in air, whereas those of PCBM are severely affected as a result of photo-induced degradation of PCBM. Furthermore, the photo-degradation of PCBM is accelerated by blending it with TQ1. While the NEXAFS spectrum of TQ1 remains unchanged upon illumination in air, its valence band spectrum shows that the occupied molecular orbitals are weakly affected. Yet, UV-Vis absorption spectra demonstrate photo-bleaching of TQ1, which is attenuated in the presence of PCBM in blend films. Illumination of the active layer of TQ1:PCBM solar cells prior to cathode deposition causes severe losses in electrical performance. PMID:27051887

  18. Inhibition of microbial growth on air cathodes of single chamber microbial fuel cells by incorporating enrofloxacin into the catalyst layer.

    PubMed

    Liu, Weifeng; Cheng, Shaoan; Sun, Dan; Huang, Haobin; Chen, Jie; Cen, Kefa

    2015-10-15

    The inevitable growth of aerobic bacteria on the surface of air cathodes is an important factor reducing the performance stability of air cathode single-chamber membrane-free microbial fuel cells (MFCs). Thus searching for effective methods to inhibit the cathodic microbial growth is critical for the practical application of MFCs. In this study, enrofloxacin (ENR), a broad spectrum fluoroquinolone antibiotic, was incorporated into the catalyst layer of activated carbon air cathodes (ACACs) to inhibit the cathodic microbial growth. The biomass content on ACACs was substantially reduced by 60.2% with ENR treatment after 91 days of MFCs operation. As a result of the inhibited microbial growth, the oxygen reduction catalytic performance of the ENR treated ACACs was much stable compared to the fast performance decline of the untreated control. Consequently, a quite stable electricity production was obtained for the MFCs with the ENR treated ACACs, in contrast with a 22.5% decrease in maximum power density of the MFCs with the untreated cathode. ENR treatment of ACACs showed minimal effects on the anode performance. These results indicate that incorporating antibiotics into ACACs should be a simple and effective strategy to inhibit the microbial growth and improve the long-term stability of the performance of air cathode and the electricity production of MFCs. PMID:25957076

  19. Investigations of the boundary-layer control on a full scale swept wing with air bled off from the turbojet

    NASA Technical Reports Server (NTRS)

    Rebuffet, Pierre; Poisson-Quinton, PH

    1952-01-01

    The following account reviews the various stages of a research program relative to the high-lift devices on a swept wing by combined suction and blowing (jet action), with ejectors fed by air bled off (extracted) from the turbojet. After reviewing the essential principles of the boundary-layer control obtained by comparison with theory, the electric analogies and the wind-tunnel tests as well as the essential elements of ejector operations, the writers describe the tests made in the large tunnel at Chalais-Meudon on a full-scale model of the SO 6020 wing.

  20. A theoretical remark about waves on a static water surface beneath a layer of moving air

    NASA Astrophysics Data System (ADS)

    Kida, T.; Hayashi, R.; Yasutomi, Z.

    1990-12-01

    Grundy and Tuck (1987) treat the problem of large-amplitude waves on an air-water interface where the air is a steady nonuniform flow and the water is stationary. Both periodic nonlinear Stokes-like waves far downstream and a configuration of the water surface from the edge region of a hovercraft were computed. However, there is no work that treats the existence of such Stokes-like waves theoretically. The present work aims to prove the existence of such solutions in the case where the cushion pressure is low, that is, the depression at the upstream stagnation point from the mean water level is small.

  1. Air-Ice-Ocean Interaction: Turbulent Ocean Boundary Layer Exchange Processes

    NASA Astrophysics Data System (ADS)

    Weller, Robert

    2010-01-01

    This is a well-written book about the upper boundary layer of the ice-covered ocean. It combines a presentation of the physics and associated equations governing the structure of and mixing within the ice-ocean boundary layer (IOBL) with illustrative examples from fieldwork carried out during the author's career. The examples and good graphics do much to solidify the understanding the reader develops about these matters. Together with short summary glossaries of key quantities and parameters at the end of many chapters, the author's approach of weaving theory and observations together has resulted in an excellent text.

  2. Air-stable ink for scalable, high-throughput layer deposition

    DOEpatents

    Weil, Benjamin D; Connor, Stephen T; Cui, Yi

    2014-02-11

    A method for producing and depositing air-stable, easily decomposable, vulcanized ink on any of a wide range of substrates is disclosed. The ink enables high-volume production of optoelectronic and/or electronic devices using scalable production methods, such as roll-to-roll transfer, fast rolling processes, and the like.

  3. The evolution of the boundary layer and its effect on air chemistry in the Phoenix area.

    SciTech Connect

    Fast, J. D.; Doran, J. C.; Shaw, W. J.; Coulter, R. L.; Martin, T. J.; Environmental Research; PNNL

    2000-09-27

    During a 4-week period in May and June of 1998, meteorological and chemical measurements were made as part of a field campaign carried out in the Phoenix area. Data from the field campaign provide the first detailed measurements of the properties of the convective boundary layer in this area and of the effects of these properties on ozone levels. The meteorological and chemical measurements have been combined with results from a set of meteorological, particle, and chemistry models to study ozone production, transport, and mixing in the vicinity of Phoenix. Good agreement between the simulations and observations was obtained, and the results have been used to illustrate several important factors affecting ozone patterns in the region. Heating of the higher terrain north and east of Phoenix regularly produced thermally driven circulations from the south and southwest through most of the boundary layer during the afternoon, carrying the urban ozone plume to the northeast. The combination of deep mixed layers and moderate winds aloft provided good ventilation of the Phoenix area on most days so that multiday buildups of locally produced ozone did not appear to contribute significantly to ozone levels during the study period. Sensitivity simulations determined that 20 to 40% of the afternoon surface ozone mixing ratios (corresponding to 15 to 35 ppb) were due to vertical mixing processes that entrained reservoirs of ozone into the growing convective boundary layer. The model results also indicated that ozone production in the region is volatile organic compound limited.

  4. Air-coupled ultrasonic investigation of multi-layered composite materials.

    PubMed

    Kazys, R; Demcenko, A; Zukauskas, E; Mazeika, L

    2006-12-22

    Air-coupled ultrasonics is fine alternative for the immersion testing technique. Usually a through transmission and a pitch-catch arrangement of ultrasonic transducers are used. The pitch-catch arrangement is very attractive for non-destructive testing and evaluation of materials, because it allows one-side access to the object. However, this technique has several disadvantages. It is sensitive to specularly reflected and edge waves. A spatial resolution depends on a distance between the transducers. A new method for detection and visualisation of inhomogeneities in composite materials using one-side access air-coupled ultrasonic measurement technique is described. Numerical predictions of Lamb wave interaction with a defect in a composite material are carried out and the interaction mechanism is explained. Experimental measurements are carried out with different arrangements of the transducers. The proposed method enables detect delamination and impact type defects in honeycomb materials. PMID:16797664

  5. A simple theoretical model of heat and moisture transport in multi-layer garments in cool ambient air.

    PubMed

    Wissler, Eugene H; Havenith, George

    2009-03-01

    Overall resistances for heat and vapor transport in a multilayer garment depend on the properties of individual layers and the thickness of any air space between layers. Under uncomplicated, steady-state conditions, thermal and mass fluxes are uniform within the garment, and the rate of transport is simply computed as the overall temperature or water concentration difference divided by the appropriate resistance. However, that simple computation is not valid under cool ambient conditions when the vapor permeability of the garment is low, and condensation occurs within the garment. Several recent studies have measured heat and vapor transport when condensation occurs within the garment (Richards et al. in Report on Project ThermProject, Contract No. G6RD-CT-2002-00846, 2002; Havenith et al. in J Appl Physiol 104:142-149, 2008). In addition to measuring cooling rates for ensembles when the skin was either wet or dry, both studies employed a flat-plate apparatus to measure resistances of individual layers. Those data provide information required to define the properties of an ensemble in terms of its individual layers. We have extended the work of previous investigators by developing a rather simple technique for analyzing heat and water vapor transport when condensation occurs within a garment. Computed results agree well with experimental results reported by Richards et al. (Report on Project ThermProject, Contract No. G6RD-CT-2002-00846, 2002) and Havenith et al. (J Appl Physiol 104:142-149, 2008). We discuss application of the method to human subjects for whom the rate of sweat secretion, instead of the partial pressure of water on the skin, is specified. Analysis of a more complicated five-layer system studied by Yoo and Kim (Text Res J 78:189-197, 2008) required an iterative computation based on principles defined in this paper. PMID:19125281

  6. Karst evolution in the Cordillera de la Sal (Atacama, Chili)

    NASA Astrophysics Data System (ADS)

    de Waele, J.; Forti, P.; Picotti, V.; Zini, L.; Cucchi, F.; Brook, G.

    2009-04-01

    Rock salt composed of halite is at least three orders of magnitude more soluble than limestone. Because of this very high solubility rock salt rarely crops out extensively at the surface and is readily dissolved leaving insoluble residue (mainly clays and marls). Rock salt can only survive at the surface where climate is extremely arid and normally displays a large set of typical solution morphologies similar to those developed on limestone. Solution of rock salt also leads to the formation of underground caves several km long. Close to the village of San Pedro de Atacama, North of the Salar de Atacama basin, there is an important NNE-SSW trending elongated anticlinal ridge composed of Oligo-Miocene evaporitic rocks known under the name Cordillera de la Sal. The thick salt beds of this ridge, even in this hyperarid climate (mean annual rainfall is below 20 mm/y and there may be no rain for several years), have been karstified by occasional rains and have a well developed surface karst geomorphology with extremely sharp rillenkarren often isolating salt pinnacles of up to 15 m in height. During the past 10 years interesting salt caves have been discovered in these halite beds and a detailed morphological study has been carried out both at the surface and in the most important caves with the aim of understanding the mechanisms responsible for their formation and evolution. Sixteen wood and bone fragments from the ceilings of caves and from diamictons in passages have been AMS radiocarbon dated, allowing us to determine when the cave systems formed and when the major sediment units were emplaced. In fact, cave formation appears to have been very rapid, with development of huge cave passages in salt (more than 10 m wide and 30 m high) in less than 2,000 years. Moreover, detailed surveys of cave morphology (e.g. meanders, erosion benches) and sediments (diamictons) suggest that the caves were formed by short-lived flash floods, probably produced by single extreme

  7. Air-bridged lateral growth of an Al0.98Ga0.02N layer by introduction of porosity in an AlN buffer

    NASA Astrophysics Data System (ADS)

    Wang, T.; Bai, J.; Parbrook, P. J.; Cullis, A. G.

    2005-10-01

    We demonstrated air-bridged lateral growth of an Al0.98Ga0.02N layer with significant dislocation reduction by introduction of a porous AlN buffer underneath via metalorganic chemical vapor deposition. By modifying growth conditions, a porous AlN layer and an atomically flat AlN layer have been obtained for comparison, confirmed by atomic force microscopy. An Al0.98Ga0.02N layer was subsequently grown on both the porous AlN layer and the atomically flat AlN layer under identical conditions. Significant dislocation reduction was achieved for the Al0.98Ga0.02N layer grown on the porous AlN buffer layer, compared to the layer grown on the atomically flat AlN layer, as observed by transmission electron microscopy. Clear bubbles from the layer grown on the porous AlN buffer layer have been observed, while in contrast, there was not any bubble from the layer on the flat AlN buffer, confirming the mechanism of lateral growth for dislocation reduction. Asymmetric x-ray diffraction studies also indicated that the crystal quality was dramatically improved using the porous AlN buffer layer.

  8. CALIPSO inferred most probable heights of global dust and smoke layers

    NASA Astrophysics Data System (ADS)

    Huang, Jingfeng; Guo, Jianping; Wang, Fu; Liu, Zhaoyan; Jeong, Myeong-Jae; Yu, Hongbin; Zhang, Zhibo

    2015-05-01

    The vertical location of aerosol layers is critical for determining predominance of aerosol radiative and microphysical effects in aerosol-cloud-precipitation-climate interaction. The spaceborne lidar system, the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), provides an unprecedented opportunity to observe vertical distributions of global aerosol layers. In this study we examine the most probable height (MPH) of dust and smoke layers, which are calculated either from aerosol occurrence frequency (OF) in vertical feature mask or aerosol extinction profile. The study focuses on six high-aerosol-loading regions where aerosols are of great interest in a range of scientific topics: Saharan Air Layer (SAL) over Tropical Atlantic, West African Monsoon region (WAM), Southeast Atlantic Ocean (SAO), Southeast Asia (SEA) and South China Sea, Amazon (AMZ), and Northwestern Pacific (NWP). The analysis revealed interesting spatial and seasonal variability of different vertical mixture features over these regions: seasonal migration of dust layers over SAL, separation and mixture of dust and smoke layers over WAM and NWP, and smoke layer above clouds over SAO, SEA, and AMZ. Results also indicated that the OF-based MPH tends to be much higher than the aerosol optical depth (AOD)-based MPH, owing to the predominating near-surface sources. Within the same vertical resolution grid of CALIPSO, aerosols are found with higher OF at higher levels but AOD tends to increase toward lower levels, because most aerosol sources are near the surface and the aerosol layers transported to high altitudes are generally much more diluted over larger spatial domain than those near the surface.

  9. Transitions of cloud-topped marine boundary layers characterized by AIRS, MODIS, and a large eddy simulation model

    SciTech Connect

    Yue, Qing; Kahn, Brian; Xiao, Heng; Schreier, Mathias; Fetzer, E. J.; Teixeira, J.; Suselj, Kay

    2013-08-16

    Cloud top entrainment instability (CTEI) is a hypothesized positive feedback between entrainment mixing and evaporative cooling near the cloud top. Previous theoretical and numerical modeling studies have shown that the persistence or breakup of marine boundary layer (MBL) clouds may be sensitive to the CTEI parameter. Collocated thermodynamic profile and cloud observations obtained from the Atmospheric Infrared Sounder (AIRS) and Moderate Resolution Imaging Spectroradiometer (MODIS) instruments are used to quantify the relationship between the CTEI parameter and the cloud-topped MBL transition from stratocumulus to trade cumulus in the northeastern Pacific Ocean. Results derived from AIRS and MODIS are compared with numerical results from the UCLA large eddy simulation (LES) model for both well-mixed and decoupled MBLs. The satellite and model results both demonstrate a clear correlation between the CTEI parameter and MBL cloud fraction. Despite fundamental differences between LES steady state results and the instantaneous snapshot type of observations from satellites, significant correlations for both the instantaneous pixel-scale observations and the long-term averaged spatial patterns between the CTEI parameter and MBL cloud fraction are found from the satellite observations and are consistent with LES results. This suggests the potential of using AIRS and MODIS to quantify global and temporal characteristics of the cloud-topped MBL transition.

  10. Direct calculation of acoustic streaming including the boundary layer phenomena in an ultrasonic air pump

    NASA Astrophysics Data System (ADS)

    Wada, Yuji; Koyama, Daisuke; Nakamura, Kentaro

    2012-05-01

    Direct finite difference fluid simulation of acoustic streaming on the fine-meshed three-dimensiona model by graphics processing unit (GPU)-oriented calculation array is discussed. Airflows due to the acoustic traveling wave are induced when an intense sound field is generated in a gap between a bending transducer and a reflector. Calculation results showed good agreement with the measurements in the pressure distribution. In addition to that, several flow-vortices were observed near the boundary of the reflector and the transducer, which have been often discussed in acoustic tube near the boundary, and have never been observed in the calculation in the ultrasonic air pump of this type.

  11. Mixing layer height and the implications for air pollution over Beijing, China

    NASA Astrophysics Data System (ADS)

    Tang, G.; Zhang, J.; Münkel, C.; Song, T.; Hu, B.; Schäfer, K.; Liu, Z.; Xin, J.; Suppan, P.; Wang, Y.

    2015-10-01

    The mixing layer is an important meteorological factor that affects atmospheric pollution. A study of atmospheric pollution in the Beijing area was performed from July 2009 to December 2012, using a ceilometer, to observe and study the atmospheric mixing layer height (MLH). Based on a comparison and validation of multiple types of data, we evaluated the quality of the MLH data as observed by the ceilometer and found that the ceilometer underestimates MLH during neutral stratification caused by strong winds, whereas it overestimates MLH during dust crossing. By combining conventional meteorological data and PM2.5 and PM10 observational data, we screened the observational results for the MLH, and the ceilometer observations were fairly consistent with the meteorological radiosonde profile results. The correlation coefficient is more than 0.9, and the effective rate of acquired data is near 80 %. Further analysis of the variation in the MLH indicates that the MLH in the Beijing area exhibits the feature of being low in autumn and winter and being high in spring and summer. There is a significant correlation between the variation in the MLH and the sensible heat flux, whereas the diurnal variation in the mixing layer during summer is affected by the circulation of mountainous plain winds. By applying visibility as the index for the classification of atmospheric pollution degree, it is found that in comparison with a clear day, the variation of sensible heat and buoyancy term in turbulent kinetic energy (TKE) of a slight haze day is insignificant, but the reduction of shear term in TKE is near 70 % when visibility decreased from 10 to 5 km; in comparison with the slight haze day, the variation of shear term in TKE of medium and heavy haze days is insignificant, but the declination of sensible heat and buoyancy term in TKE are about 60 % when visibility decreased from 5 to 1 km. Although the correlation between the daily variation of MLH and visibility is very poor, the

  12. Large-scale recrystallization of the S-layer of Bacillus coagulans E38-66 at the air/water interface and on lipid films.

    PubMed Central

    Pum, D; Weinhandl, M; Hödl, C; Sleytr, U B

    1993-01-01

    S-layer protein isolated from Bacillus coagulans E38-66 could be recrystallized into large-scale coherent monolayers at an air/water interface and on phospholipid films spread on a Langmuir-Blodgett trough. Because of the asymmetry in the physiochemical surface properties of the S-layer protein, the subunits were associated with their more hydrophobic outer face with the air/water interface and oriented with their negatively charged inner face to the zwitterionic head groups of the dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylethanolamine (DPPE) monolayer films. The dynamic crystal growth at both types of interfaces was first initiated at several distant nucleation points. The individual monocrystalline areas grew isotropically in all directions until the front edge of neighboring crystals was met. The recrystallized S-layer protein and the S-layer-DPPE layer could be chemically cross-linked from the subphase with glutaraldehyde. Images PMID:8478338

  13. Tritium release from Ti-T layers in air, in aqueous media and in animal experiments.

    PubMed

    Bíró, J; Fehér, I; Máté, L; Varga, L

    1978-01-01

    In connection with Ti-T incorporation hazard to which operators of neutron generators are exposed the release of tritium from Ti-T preparations of different ages was studied in experiments carried out in air, in aqueous media and in living animals. Samples were prepared with activities from 10 to 30 mCi and the effect of storage on the tritium release rate was also observed. In 250 days a fraction of 10(-3) of the tritium activity was absorbed by aqueous liquids. In air the release varied from 10(-6) to 10(-7) per hour. The Ti-T samples of different ages, introduced surgically into the abdominal cavity of rats, showed the tritium release rate to decrease with time. The tritium activity observable in the circulation was 5 to 6 orders of magnitude smaller compared with the introduced value. The observations permit the inference that in the case of Ti-T incorporation only a minor fraction of the tritium burden can be assessed from the activity measured in the urine. PMID:754442

  14. The relationship between ozone formation and air temperature in the atmospheric surface layer

    NASA Astrophysics Data System (ADS)

    Belan, Boris D.; Savkin, Denis; Tolmachev, Gennadii

    2016-04-01

    Studying the formation and dynamics of ozone in the atmosphere is important due to several reasons. First, the contribution of tropospheric ozone to the global greenhouse effect is only slightly less than that of water vapor, carbon dioxide, and methane. Second, tropospheric ozone acts as a strong poison that has negative effects on human health, animals, and vegetation. Third, being a potent oxidizer, ozone destroys almost all materials, including platinum group metals and compounds. Fourthly, ozone is formed in situ from precursors as a result of photochemical processes, but not emitted into the atmosphere by any industrial enterprises directly. In this work, we present some results of the study aimed at the revealing relationship between ozone formation rate and surface air temperature in the background atmosphere. It has been found that this relationship is nonlinear. Analysis of the possible reasons showed that the nonlinear character of this relationship may be due to a nonlinear increase in the reaction constants versus air temperature and a quadratic increase in the concentration of hydrocarbons with increasing temperature. This work was supported by the Ministry of Education and Science contract no.14.613.21.0013 (ID: RFMEFI61314X0013).

  15. A Long-Lived Tracer Perspective on the Origin of Air in the Tropical Tropopause Layer during ATTREX

    NASA Astrophysics Data System (ADS)

    Hintsa, E. J.; Moore, F.; Dutton, G. S.; Hall, B. D.; Nance, J. D.; Elkins, J. W.; Gao, R.; Rollins, D. W.; Thornberry, T. D.; Watts, L.; Fahey, D. W.; Daube, B. C.; Pittman, J. V.; Wofsy, S. C.; Atlas, E. L.; Navarro, M. A.; Dessler, A. E.; Mahoney, M.

    2013-12-01

    The origin of air in the tropical tropopause layer (TTL) and the subsequent transport pathways of these air masses play a critical role in the delivery of trace gases, including ozone depleting substances and water vapor, to the stratosphere. The Airborne Tropical Tropopause Experiment (ATTREX) is designed to study this transport and processing in the TTL over the Pacific Ocean, including how dehydration occurs in this region and how trace gases involved in ozone depletion and climate reach the tropical lower stratosphere. For this mission, the NASA Global Hawk aircraft is carrying a suite of in situ and remote sensing instruments for trace gases, aerosols, radiation, and meteorology. Two deployments have occurred from NASA/Dryden Flight Research Center, with flights to the eastern and central tropical Pacific. Two more deployments, targeting the western equatorial Pacific, are planned for 2014 from Guam and one other location. Over 100 vertical profiles from about 14 to 18 km have now been obtained from the tropics to midlatitudes, as well as long sections at nearly constant altitude. Results are shown here from the UAS Chromatograph for Atmospheric Trace Species (UCATS) instrument and other sensors. UCATS was configured to measure the long-lived tracers N2O, SF6, H2, and CH4, as well as water vapor, CO, and ozone. Results thus far have shown a mix of midlatitude and tropical air in the tropical and subtropical lower stratosphere, particularly for flights in November 2011. Recent results from February 2013 indicate much more homogeneous air masses in the TTL during this period. This homogeneity may be related to fact that these flights occurred in the middle of (northern) winter rather than fall, or to the 'sudden stratospheric warming' in January 2013, with sinking motion in the Arctic polar region and a corresponding rising motion and cooling in the tropics. Data will be presented in the context of trajectory model calculations of the origin and fate of the air

  16. Restriction of a bacteriophage of Streptomyces albus G involving endonuclease SalI.

    PubMed Central

    Chater, K F; Wilde, L C

    1976-01-01

    The bacteriophage Pa16, isolated from soil on Streptomyces albus G, was restricted when transferred from an alternative host back to S. albus G. Extracted unmodified Pa16 deoxyribonucleic acid was cleaved at a single site by a cell-free extract of S. albus G. Fractions cleaving Pal6 deoxyribonucleic acid contained the endonuclease SalI first described by J. Arrand, P. Myers, and R. J. Roberts (unpublished data). A mutant of S. albus G was isolated which was defective in both restriction and modification of Pal6. This mutant lacked SalI activity. It is concluded that SalI is the agent of restriction of Pal6 by S. albus G. Images PMID:977549

  17. Non-Boltzmann Modeling for Air Shock-Layer Radiation at Lunar-Return Conditions

    NASA Technical Reports Server (NTRS)

    Johnston, Christopher O.; Hollis, Brian R.; Sutton, Kenneth

    2008-01-01

    This paper investigates the non-Boltzmann modeling of the radiating atomic and molecular electronic states present in lunar-return shock-layers. The Master Equation is derived for a general atom or molecule while accounting for a variety of excitation and de-excitation mechanisms. A new set of electronic-impact excitation rates is compiled for N, O, and N2+, which are the main radiating species for most lunar-return shock-layers. Based on these new rates, a novel approach of curve-fitting the non-Boltzmann populations of the radiating atomic and molecular states is developed. This new approach provides a simple and accurate method for calculating the atomic and molecular non-Boltzmann populations while avoiding the matrix inversion procedure required for the detailed solution of the Master Equation. The radiative flux values predicted by the present detailed non-Boltzmann model and the approximate curve-fitting approach are shown to agree within 5% for the Fire 1634 s case.

  18. Measured and calculated wall temperatures on air-cooled turbine vanes with boundary layer transition

    NASA Astrophysics Data System (ADS)

    Liebert, C. H.; Gaugler, R. E.; Gladden, H. J.

    1982-11-01

    Convection cooled turbine vane metal wall temperatures experimentally obtained in a hot cascade for one vane design were compared with wall temperatures calculated with TACT1 and STAN5 computer codes which incorporated various models for predicting laminar-to-turbulent boundary layer transition. Favorable comparisons on both vane surface were obtained at high Reynolds number with only one of these transition models. When other models were used, temperature differences between calculated and experimental data obtained at the high Reynolds number were as much as 14 percent in the separation bubble region of the pressure surface. On the suction surface and at lower Reynolds number, predictions and data unsatisfactorily differed by as much as 22 percent. Temperature differences of this magnitude can represent orders of magnitude error in blade life prediction.

  19. Saharan Air and Atlantic Tropical Cyclone Suppression From a Global Modeling Perspective

    NASA Technical Reports Server (NTRS)

    Reale, O.; Lau, W. K. M.; daSilva, A.; Kim, K.-M.

    2007-01-01

    During summer 2006, the NASA African Monsoon Multidisciplinary Analysis (NAMMA) organized a field campaign in Africa called Special Observation Period (SOP-3), in which scientists in the field were involved in a number of surface network and aircraft measurements. One of the scientific goals of the campaign was to understand the nature and causes for tropical cyclogenesis originating out of African Easterly Waves (AEWs, westward propagating atmospheric disturbances sometimes associated with precursors of hurricanes), and the role that the Saharan Air Layer (SAL, a hot and dry air layer advecting large amounts of dust) can play in the formation or suppression of tropical cyclones. During the NAMMA campaign a high-resolution global model, the NASA GEOS-5, was operationally run by the NASA Global Modeling and Assimilation Office (GMAO) in support to the mission. The daily GEOS-5 forecasts were found to be very useful by decision-making scientists in the field as an aid to discriminate between developing and non-developing AEWs and plan the flight tracks. In the post-event analyses which were performed mostly by the Goddard Laboratory for Atmospheres, two events were highlighted: a non-developing AEW which appeared to have been suppressed by Saharan air, compared to a developing AEW which was the precursor of hurricane Helene. Both events were successfully predicted by the GEOS-5 during the real-time forecasts provided in support to the mission. In this work it is found that very steep moisture gradients and a strong thermal dipole, with relatively warm air in the mid-troposphere and cool air below, are associated with SAL in both the GEOS-5 forecasts and the NCEP analyses, even at -great distance- from the Sahara. The presence of these unusual thermodynamic features over the Atlantic Ocean, at several thousands of kilometers from the African coastline, is suggestive that SAL mixing is very minimal and that the model's capability of retaining the different properties

  20. Effect of atmospheric mixing layer depth variations on urban air quality and daily mortality during Saharan dust outbreaks

    PubMed Central

    Pandolfi, M.; Tobias, A.; Alastuey, A.; Sunyer, J.; Schwartz, J.; Lorente, J.; Pey, J.; Querol, X.

    2016-01-01

    Several epidemiological studies have shown that the outbreaks of Saharan dust over southern European countries can cause negative health effects. The reasons for the increased toxicity of airborne particles during dust storms remain to be understood although the presence of biogenic factors carried by dust particles or the interaction between dust and man-made air pollution have been hypothesized as possible causes. Intriguingly, recent findings have also demonstrated that during Saharan dust outbreaks the local man-made particulates can have stronger effects on health than during days without outbreaks. We show that the thinning of the mixing layer (ML) during Saharan dust outbreaks, systematically described here for the first time, can trigger the observed higher toxicity of ambient local air. The mixing layer height (MLH) progressively reduced with increasing intensity of dust outbreaks thus causing a progressive accumulation of anthropogenic pollutants and favouring the formation of new fine particles or specific relevant species likely from condensation of accumulated gaseous precursors on dust particles surface. Overall, statistically significant associations of MLH with all-cause daily mortality were observed. Moreover, as the MLH reduced, the risk of mortality associated with the same concentration of particulate matter increased due to the observed pollutants accumulation. The association of MLH with daily mortality and the effect of ML thinning on particle toxicity exacerbated when Saharan dust outbreaks occurred suggesting a synergic effect of atmospheric pollutants on health which was amplified during dust outbreaks. Moreover, the results may reflect higher toxicity of primary particles which predominate on low MLH days. PMID:25051327

  1. Influence of cathode opening size and wetting properties of diffusion layers on the performance of air-breathing PEMFCs

    NASA Astrophysics Data System (ADS)

    Schmitz, A.; Tranitz, M.; Eccarius, S.; Weil, A.; Hebling, C.

    Air-breathing PEMFCs consist of an open cathodic side to allow an entirely passive supply of oxygen by diffusion. Furthermore, a large fraction of the produced water is removed by evaporation from the open cathode. Gas diffusion layers (GDLs) and the opening size of the cathode have a crucial influence on the performance of an air-breathing PEMFC. In order to assure an unobstructed supply of oxygen the water has to be removed efficiently and condensation in the GDL has to be avoided. On the other hand good humidification of the membrane has to be achieved to obtain high protonic conductivity. In this paper the influence of varying cathodic opening sizes (33%, 50% and 80% opening ratios) and of GDLs with different wetting properties are analysed. GDLs with hydrophobic and hydrophilic properties are prepared by coating of untreated GDLs (Toray ® carbon paper TGP-H-120, thickness of 350 μm). The air-breathing PEMFC test samples are realised using printed circuit board (PCB) technology. The cell samples were characterised over the entire potential range (0-0.95 V) by extensive measurements of the current density, the temperature and the cell impedance at 1 kHz. Additionally, measurements of the water balance were carried out at distinct operation points. The best cell performance was achieved with the largest opening ratio (80%) and an untreated GDL. At the maximum power point, this cell sample achieved a power density of 100 mW cm -2 at a moderate cell temperature of 43 °C. Furthermore, it could be shown that GDLs with hydrophilic or intense hydrophobic properties do not improve the performance of an air-breathing PEMFC. Based on the extensive characterisations, two design rules for air-breathing PEMFCs could be formulated. Firstly, it is crucial to maximise the cathode opening as far as an appropriate compression pressure of the cell assembly and therewith low contact resistance can be assured. Secondly, it is advantageous to use an untreated, slightly hydrophobic

  2. Ozone in the Boundary Layer air over the Arctic Ocean - measurements during the TARA expedition

    NASA Astrophysics Data System (ADS)

    Bottenheim, J. W.; Netcheva, S.; Morin, S.; Nghiem, S. V.

    2009-03-01

    A full year of measurements of surface ozone over the Arctic Ocean far removed from land is presented (81° N - 88° N latitude). The data were obtained during the drift of the French schooner TARA between September 2006 and January 2008, while frozen in the Arctic Ocean. The data confirm that long periods of virtually total absence of ozone occur in the spring (mid March to mid June) after Polar sunrise. At other times of the year ozone concentrations are comparable to other oceanic observations with winter mole fractions of ca. 30-40 nmol mol-1 and summer minima of ca. 20 nmol mol-1. Contrary to earlier observations from ozone sonde data obtained at Arctic coastal observatories, the ambient temperature was well above -20°C during most ODEs (ozone depletion episodes). Backwards trajectory calculations suggest that during these ODEs the air had previously been in contact with the frozen ocean surface for several days and originated largely from the Siberian coast where several large open flaw leads developed in the spring of 2007.

  3. From pores to eddies - linking diffusion-based evaporative fluxes from porous surfaces with a turbulent air boundary layer

    NASA Astrophysics Data System (ADS)

    Haghighi, E.; Or, D.

    2012-04-01

    Evaporation affects hydration and energy balance of terrestrial surfaces. Evaporation rates exhibit complex dynamics reflecting interactions between external conditions and internal transport properties of a the drying porous surface Motivated by recent progress in estimating evaporative fluxes from isolated pores across laminar air sublayer, we seek to expand the description and quantify evaporation across a turbulent boundary layer. We adopt concepts from surface renewal (SR) theory focusing on turbulent exchange with individual eddies and linking eddies surface footprint and their local boundary layer over patches of a drying surface. The model resolves diffusive exchange during limited residence time and integrates fluxes over the entire surface to quantify mean evaporative fluxes from drying surfaces into turbulent airflows accounting for subsurface internal transport processes and diffusive exchanges. Input parameters and model evaluation would be based on data from spatially and temporally resolved Infrared (IR) thermography of drying surfaces under prescribe turbulent regimes conducted in a wind-tunnel experiment. The study provides basic ingredients and building blocks essential for upscaling the results to estimation of evaporative fluxes at the field and landscape scales. Keywords: Evaporation; Turbulent Coupling; Surface Renewal; Infrared Imaging.

  4. Using ammonium bicarbonate as pore former in activated carbon catalyst layer to enhance performance of air cathode microbial fuel cell

    NASA Astrophysics Data System (ADS)

    Li, Da; Qu, Youpeng; Liu, Jia; He, Weihua; Wang, Haiman; Feng, Yujie

    2014-12-01

    The rolling catalyst layers in air cathode microbial fuel cells (MFCs) are prepared by introducing NH4HCO3 as pore former (PF) with four PF/activated carbon mass ratios of 0.1, 0.2, 0.3 and 1.0. The maximum power density of 892 ± 8 mW m-2 is obtained by cathodes with the mass ratio of 0.2, which is 33% higher than that of the control reactor (without PF, 671 ± 22 mW m-2). Pore analysis indicates the porosity increases by 38% and the major pore range concentrates between 0.5 μm-0.8 μm which likely facilitates to enrich the active reaction sites compared to 0.8 μm-3.0 μm in the control and other PF-cathodes. In addition, pore structure endows the cathode improved exchange current density by 2.4 times and decreased charge transfer resistance by 44%, which are the essential reasons to enhance the oxygen reduction. These results show that addition of NH4HCO3 proves an effective way to change the porosity and pore distribution of catalyst layers and then enhance the MFC performance.

  5. Surface potential of methyl isobutyl carbinol adsorption layer at the air/water interface.

    PubMed

    Phan, Chi M; Nakahara, Hiromichi; Shibata, Osamu; Moroi, Yoshikiyo; Le, Thu N; Ang, Ha M

    2012-01-26

    The surface potential (ΔV) and surface tension (γ) of MIBC (methyl isobutyl carbinol) were measured on the subphase of pure water and electrolyte solutions (NaCl at 0.02 and 2 M). In contrast to ionic surfactants, it was found that surface potential gradually increased with MIBC concentration. The ΔV curves were strongly influenced by the presence of NaCl. The available model in literature, in which surface potential is linearly proportional to surface excess, failed to describe the experimental data. Consequently, a new model, employing a partial charge of alcohol adsorption layer, was proposed. The new model predicted the experimental data consistently for MIBC in different NaCl solutions. However, the model required additional information for ionic impurity to predict adsorption in the absence of electrolyte. Such inclusion of impurities is, however, unnecessary for industrial applications. The modeling results successfully quantify the influence of electrolytes on surface potential of MIBC, which is critical for froth stability. PMID:22172075

  6. Explaining a Consistent Morning NOx Maximum in the Clean Air Forest Boundary Layer

    NASA Astrophysics Data System (ADS)

    Shepson, P. B.; Alaghmand, M.; Bertman, S. B.; Carroll, M.; Edburg, S. L.; Jobson, B. T.; Keutsch, F. N.; Lamb, B. K.; Starn, T.; Stevens, P. S.; Wallace, W.; Zhou, X.

    2010-12-01

    Measurements of nitrogen oxides (NOx) at continental surface sites have frequently revealed the presence of an early morning maximum in the NOx concentration. While this observation has most often been interpreted as the result of downward mixing associated with breakup of the nocturnal inversion, the morning NOx peak often occurs earlier than the NBL breakup. Given the importance of NOx to boundary layer photochemistry near forested environments, it is essential that this phenomenon be well understood. Here we examine a variety of measurements, including NOx measurements at various heights, during the 1998, 2001, 2008, and 2009 (CABINEX) summer intensives of the Program for Research on Oxidants: PHotochemistry, Emissions and Transport (PROPHET), at the University of Michigan Biological Station in Northern Michigan. We will discuss the results, in terms of the extent to which the observations support/refute each of the potential drivers of the morning NOx peak: 1) downward mixing, 2) photochemistry on the various surfaces present, 3) soil emissions, and 4) local and long range transport of anthropogenic NOx, and we will report on our conclusions as to the predominant/likely explanation(s) for this phenomenon.

  7. The sal3(+) gene encodes an importin-beta implicated in the nuclear import of Cdc25 in Schizosaccharomyces pombe.

    PubMed Central

    Chua, Gordon; Lingner, Carol; Frazer, Corey; Young, Paul G

    2002-01-01

    In Schizosaccharomyces pombe, the nuclear accumulation of Cdc25 peaks in G2 and is necessary for the proper timing of mitotic entry. Here, we identify the sal3(+) gene product as an importin-beta homolog that participates in the nuclear import of Cdc25. Loss of sal3(+) results in a cell cycle delay, failure to undergo G1 arrest under nitrogen-starvation conditions, and mislocalization of Cdc25 to the cytosol. Fusion of an exogenous classical nuclear localization sequence (cNLS) to Cdc25 restores its nuclear accumulation in a sal3 disruptant and suppresses the sal3 mutant phenotypes. In addition, we show that enhanced nuclear localization of Cdc25 at endogenous levels of expression advances the onset of mitosis. These results demonstrate that the nuclear translocation of Cdc25 is important for the timing of mitotic entry and that Sal3 plays an important role in this process. PMID:12399381

  8. Finite-Difference Solution for Laminar or Turbulent Boundary Layer Flow over Axisymmetric Bodies with Ideal Gas, CF4, or Equilibrium Air Chemistry

    NASA Technical Reports Server (NTRS)

    Hamilton, H. Harris, II; Millman, Daniel R.; Greendyke, Robert B.

    1992-01-01

    A computer code was developed that uses an implicit finite-difference technique to solve nonsimilar, axisymmetric boundary layer equations for both laminar and turbulent flow. The code can treat ideal gases, air in chemical equilibrium, and carbon tetrafluoride (CF4), which is a useful gas for hypersonic blunt-body simulations. This is the only known boundary layer code that can treat CF4. Comparisons with experimental data have demonstrated that accurate solutions are obtained. The method should prove useful as an analysis tool for comparing calculations with wind tunnel experiments and for making calculations about flight vehicles where equilibrium air chemistry assumptions are valid.

  9. Laboratory investigations of the heat and momentum transfer in the stably stratified air turbulent boundary layer above the wavy surface

    NASA Astrophysics Data System (ADS)

    Sergeev, Daniil; Troitskaya, Yuliya; Vdovin, Maxim

    2015-04-01

    Investigation of small scale transfer processes between the ocean and atmosphere in the boundary and its parameterization on the meteorological conditions (wind and surface waves parameters) is very important for weather forecasts modeling [1]. The accuracy of the predictions taking in to account the so named bulk-formulas strongly depends on the quality empirical data. That is why the laboratory modeling sometimes is preferable (see [2]) then in situ measurements for obtaining enough ensembles of the data with a good accuracy in control conditions, first of all in a case of severe conditions (strong winds with intensive wave breaking and sprays generation). In this investigation laboratory modeling was performed on the Thermostratified Wind-Wave Channel of the IAP RAS (see. [3]). Experiments were carried out for the wind speeds up to 18.5 m/s (corresponding the equivalent 10-m wind speed 30 m/s). For the possibility of varying parameters of surface roughness independently on the wind flow a special system basing on the submerged mosquito mesh (cell of 2*2 mm) was used (see [4]). The roughness was controlled by the depth of the mesh installation under the free surface (no waves when the mesh was on the surface and maximum wave amplitude for the maximum depth). So, for each wind speed several cases of the waves parameters were investigated. During experiments a stable stratification of the boundary layer of air flow was obtained. Temperature of the heating air was 33-37 degrees (depending on the reference wind speed), and the water temperature was 14-16 degrees. The Pitote gauge and hotwire were used together for measuring velocity and temperature profiles. Also indirect estimations of the total volume of the phase of sprays were obtained by analyzing hotwire signals errors during droplets hits. Then aerodynamic drag CD and heat transfer Ch coefficients were obtained by profiling method. It was shown that that these parameters are very sensitive to the intensity of

  10. Plastic fats from sal, mango and palm oil by lipase catalyzed interesterification.

    PubMed

    Shankar Shetty, Umesha; Sunki Reddy, Yella Reddy; Khatoon, Sakina

    2014-02-01

    Speciality plastic fats with no trans fatty acids suitable for use in bakery and as vanaspati substitute were prepared by interesterification of blends of palm stearin (PSt) with sal and mango fats using Lipozyme TLIM lipase as catalyst. The blends containing PSt/sal or PSt/mango showed short melting range and hence are not suitable as bakery shortenings. Lipase catalysed interesterification extended the plasticity or melting range of all the blends. The blends containing higher proportion of PSt with sal fat (50/50) were harder having high solids at and above body temperature and hence cannot be used as bakery shortenings. The blends with PSt/sal (30-40/60-70) after interesterification showed melting profiles similar to those of commercial hydrogenated bakery fats. Similarly, the blends containing PSt/mango (30-40/60-70) after interesterification also showed melting profiles similar to those of commercial hydrogenated shortenings. The slip melting point and solidification characteristics also confirm the plastic nature of these samples. The improvement in plasticity after interesterification is due to formation of higher melting as well as lower melting triglycerides during lipase catalysed interesterification. PMID:24493889

  11. Impact of the Loess Plateau on the atmospheric boundary layer structure and air quality in the North China Plain: a case study.

    PubMed

    Hu, Xiao-Ming; Ma, ZhiQiang; Lin, Weili; Zhang, Hongliang; Hu, Jianlin; Wang, Ying; Xu, Xiaobin; Fuentes, Jose D; Xue, Ming

    2014-11-15

    The North China Plain (NCP), to the east of the Loess Plateau, experiences severe regional air pollution. During the daytime in the summer, the Loess Plateau acts as an elevated heat source. The impacts of such a thermal effect on meteorological phenomena (e.g., waves, precipitation) in this region have been discussed. However, its impacts on the atmospheric boundary layer structure and air quality have not been reported. It is hypothesized that the thermal effect of the Plateau likely modulates the boundary layer structure and ambient concentrations of pollutants over the NCP under certain meteorological conditions. Thus, this study investigates such effect and its impacts using measurements and three-dimensional model simulations. It is found that in the presence of daytime westerly wind in the lower troposphere (~1 km above the NCP), warmer air above the Loess Plateau was transported over the NCP and imposed a thermal inversion above the mixed boundary layer, which acted as a lid and suppressed the mixed layer growth. As a result, pollutants accumulated in the shallow mixed layer and ozone was efficiently produced. The downward branch of the thermally-induced Mountain-Plains Solenoid circulation over the NCP contributed to enhancing the capping inversion and exacerbating air pollution. Previous studies have reported that low mixed layer, a factor for elevated pollution in the NCP, may be caused by aerosol scattering and absorption of solar radiation, frontal inversion, and large scale subsidence. The present study revealed a different mechanism (i.e., westerly warm advection) for the suppression of the mixed layer in summer NCP, which caused severe O3 pollution. This study has important implications for understanding the essential meteorological factors for pollution episodes in this region and forecasting these severe events. PMID:25192929

  12. The Coupled Boundary Layers and Air-Sea Transfer (CBLAST) Experiments at the Martha's Vineyard Coastal Observatory

    NASA Astrophysics Data System (ADS)

    Edson, J. B.

    2001-12-01

    The Woods Hole Oceanographic Institution (WHOI) completed the initial phase of the Martha's Vineyard Coastal Observatory (MVCO) in July of 2001. The MVCO is being using to monitor coastal atmospheric and oceanic processes. Specifically, the observatory is expected to: - Provide continuous long-term observations for climate studies. - Provide a reliable system and rugged sensors that allow opportunistic sampling of extreme events. - Provide a local climatology for intensive, short duration field campaigns. - Further facilitate regional studies of coastal processes by providing infrastructure that supports easy access to power and data. This talk provides an example of the last two objectives using the low wind component of the Office of Naval Research's (ONR) Coupled Boundary Layers and Air-Sea Transfer (CBLAST) program. CBLAST-LOW has been designed to investigate air-sea interaction and coupled atmospheric and oceanic boundary layer dynamics at low wind speeds where the dynamic processes are driven and/or strongly modulated by thermal forcing. This effort is being carried out by scientists at WHOI, NPS, NOAA, NRL, Rutgers, UW/APL, JH/APL, OSU, NCAR, and other institutions, and includes observational and modeling components. The MVCO is providing observations and infrastructure in support of several intensive operating periods in the summers of 2001, 2002, and possibly 2003. During these periods, the observational network around the observatory was and will be greatly expanded using traditional oceanographic moorings and bottom mounted instrumentation, innovative 2- and 3-D moored and drifting arrays, survey ships, AUVs, satellite remote sensing, and heavily instrumented aircraft. In addition, the MVCO cabled components will be extended out to the 20-m isobath where we plan to deploy a 35-m tower. The tower will be instrumented from 15-m above the ocean surface to the ocean bottom with instruments capable of directly measuring the momentum, heat, and radiative

  13. The relation between air pollution data and planetary boundary layer quantities in a complex coastal industrial site nearby populated areas.

    NASA Astrophysics Data System (ADS)

    Mammarella, M. C.; Grandoni, G.; Fernando, J.; Cacciani, M.; di Sabatino, S.; Favaron, M.; Fedele, P.

    2010-09-01

    The connection among boundary layer phenomena, atmospheric pollutant dynamics and human health is an established fact, taking many different forms depending on local characteristics, including slope and position of relief and/or coastline, surface roughness, emission patterns. The problem is especially interesting in complex and coastal terrain, where concurrence of slope and sea induced local circulation interact reciprocally, yielding a complex pattern whose interpretation may go beyond pure modeling, and devise specific measurements among which the planetary boundary layer (PBL) height. An occasion for studying this important theme has been offered by Regione Molise and Valle del Biferno Consortium (COSIB), for the specific case of the industrial complex of Valle del Biferno, 3 km inland of Termoli, in Central Italy, on the Adriatic coast. The local government, sensitive to air quality and public health in the industrial area, together with COSIB has co-financed a research project aimed at gaining knowledge about local meteorology, PBL phenomena and atmospheric pollutant dispersion in the area. Expected results include new air quality monitoring and control methodologies in Valle del Biferno for a sustainable development in an environmentally respectful manner, at a site already characterized by a high environmental and landscape value. The research project, developed by ENEA, has began in 2007 and will conclude in December 2010. Project activities involve research group from Europe, the United States of America, and the Russian Federation. Scientific and practical results will be published and presented in occasion of the final workshop to be held on project conclusion. The scientific interest of Valle del Biferno case stems from the specific local characteristics at site. Given the valley orientation respect to mean synoptic circulation, local effects as sea and slope breezes are dominant, and a complex wind regime develops affecting local transport and

  14. Semi-rechargeable Aluminum-Air Battery with a TiO2 Internal Layer with Plain Salt Water as an Electrolyte

    NASA Astrophysics Data System (ADS)

    Mori, Ryohei

    2016-07-01

    To develop a semi-rechargeable aluminum-air battery, we attempted to insert various kinds of ceramic oxides between an aqueous NaCl electrolyte and an aluminum anode. From cyclic voltammetry experiments, we found that some of the ceramic oxide materials underwent an oxidation-reduction reaction, which indicates the occurrence of a faradaic electrochemical reaction. Using a TiO2 film as an internal layer, we successfully prepared an aluminum-air battery with secondary battery behavior. However, cell impedance increased as the charge/discharge reactions proceeded probably because of accumulation of byproducts in the cell components and the air cathode. Results of quantum calculations and x-ray photoelectron spectroscopy suggest the possibility of developing an aluminum rechargeable battery using TiO2 as an internal layer.

  15. Semi-rechargeable Aluminum-Air Battery with a TiO2 Internal Layer with Plain Salt Water as an Electrolyte

    NASA Astrophysics Data System (ADS)

    Mori, Ryohei

    2016-04-01

    To develop a semi-rechargeable aluminum-air battery, we attempted to insert various kinds of ceramic oxides between an aqueous NaCl electrolyte and an aluminum anode. From cyclic voltammetry experiments, we found that some of the ceramic oxide materials underwent an oxidation-reduction reaction, which indicates the occurrence of a faradaic electrochemical reaction. Using a TiO2 film as an internal layer, we successfully prepared an aluminum-air battery with secondary battery behavior. However, cell impedance increased as the charge/discharge reactions proceeded probably because of accumulation of byproducts in the cell components and the air cathode. Results of quantum calculations and x-ray photoelectron spectroscopy suggest the possibility of developing an aluminum rechargeable battery using TiO2 as an internal layer.

  16. Study of an unitised bidirectional vanadium/air redox flow battery comprising a two-layered cathode

    NASA Astrophysics Data System (ADS)

    grosse Austing, Jan; Nunes Kirchner, Carolina; Hammer, Eva-Maria; Komsiyska, Lidiya; Wittstock, Gunther

    2015-01-01

    The performance of a unitised bidirectional vanadium/air redox flow battery (VARFB) is described. It contains a two-layered cathode consisting of a gas diffusion electrode (GDE) with Pt/C catalyst for discharging and of an IrO2 modified graphite felt for charging. A simple routine is shown for the modification of a graphite felt with IrO2. A maximum energy efficiency of 41.7% at a current density of 20 mA cm-2 as well as an average discharge power density of 34.6 mW cm-2 at 40 mA cm-2 were obtained for VARFB operation at room temperature with the novel cathode setup. A dynamic hydrogen electrode was used to monitor half cell potentials during operation allowing to quantify the contribution of the cathode to the overall performance of the VARFB. Four consecutive cycles revealed that crossover of vanadium ions took place and irreversible degradation processes within the reaction unit lead to a performance decrease.

  17. Tensiometry and dilational rheology of mixed β-lactoglobulin/ionic surfactant adsorption layers at water/air and water/hexane interfaces.

    PubMed

    Dan, Abhijit; Gochev, Georgi; Miller, Reinhard

    2015-07-01

    Oscillating drop tensiometry was applied to study adsorbed interfacial layers at water/air and water/hexane interfaces formed from mixed solutions of β-lactoglobulin (BLG, 1 μM in 10 mM buffer, pH 7 - negative net charge) and the anionic surfactant SDS or the cationic DoTAB. The interfacial pressure Π and the dilational viscoelasticity modulus |E| of the mixed layers were measured for mixtures of varying surfactant concentrations. The double capillary technique was employed which enables exchange of the protein solution in the drop bulk by surfactant solution (sequential adsorption) or by pure buffer (washing out). The first protocol allows probing the influence of the surfactant on a pre-adsorbed protein layer thus studying the protein/surfactant interactions at the interface. The second protocol gives access to the residual values of Π and |E| measured after the washing out procedure thus bringing information about the process of protein desorption. The DoTAB/BLG complexes exhibit higher surface activity and higher resistance to desorption in comparison with those for the SDS/BLG complexes due to hydrophobization via electrostatic binding of surfactant molecules. The neutral DoTAB/BLG complexes achieve maximum elastic response of the mixed layer. Mixed BLG/surfactant layers at the water/oil interface are found to reach higher surface pressure and lower maximum dilational elasticity than those at the water/air surface. The sequential adsorption mode experiments and the desorption study reveal that binding of DoTAB to pre-adsorbed BLG globules is somehow restricted at the water/air surface in comparison with the case of complex formation in the solution bulk and subsequently adsorbed at the water/air surface. Maximum elasticity is achieved with washed out layers obtained after simultaneous adsorption, i.e. isolation of the most surface active DoTAB/BLG complex. These specific effects are much less pronounced at the W/H interface. PMID:25666640

  18. Atomic Layer Deposition of TiO2 for a High-Efficiency Hole-Blocking Layer in Hole-Conductor-Free Perovskite Solar Cells Processed in Ambient Air.

    PubMed

    Hu, Hang; Dong, Binghai; Hu, Huating; Chen, Fengxiang; Kong, Mengqin; Zhang, Qiuping; Luo, Tianyue; Zhao, Li; Guo, Zhiguang; Li, Jing; Xu, Zuxun; Wang, Shimin; Eder, Dominik; Wan, Li

    2016-07-20

    In this study we design and construct high-efficiency, low-cost, highly stable, hole-conductor-free, solid-state perovskite solar cells, with TiO2 as the electron transport layer (ETL) and carbon as the hole collection layer, in ambient air. First, uniform, pinhole-free TiO2 films of various thicknesses were deposited on fluorine-doped tin oxide (FTO) electrodes by atomic layer deposition (ALD) technology. Based on these TiO2 films, a series of hole-conductor-free perovskite solar cells (PSCs) with carbon as the counter electrode were fabricated in ambient air, and the effect of thickness of TiO2 compact film on the device performance was investigated in detail. It was found that the performance of PSCs depends on the thickness of the compact layer due to the difference in surface roughness, transmittance, charge transport resistance, electron-hole recombination rate, and the charge lifetime. The best-performance devices based on optimized TiO2 compact film (by 2000 cycles ALD) can achieve power conversion efficiencies (PCEs) of as high as 7.82%. Furthermore, they can maintain over 96% of their initial PCE after 651 h (about 1 month) storage in ambient air, thus exhibiting excellent long-term stability. PMID:27340730

  19. Mixed layers of β-lactoglobulin and SDS at air-water interfaces with tunable intermolecular interactions.

    PubMed

    Engelhardt, Kathrin; Weichsel, Ulrike; Kraft, Elena; Segets, Doris; Peukert, Wolfgang; Braunschweig, Björn

    2014-04-17

    Mixtures of β-lactoglobulin (BLG) and sodium dodecyl sulfate (SDS) were studied at pH 3.8 and 6.7 under equilibrium conditions. At these pH conditions, BLG carries either a positive or a negative net charge, respectively, which enables tunable electrostatic interactions between anionic SDS surfactants and BLG proteins. For pH 3.8, vibrational sum-frequency generation (SFG) and ellipsometry indicate strong BLG-SDS complex formation at air-water interfaces that is caused by attractive electrostatic interactions. The latter complexes are already formed in the bulk solution which was confirmed by a thermodynamic study of BLG-SDS mixtures using isothermal titration calorimetry (ITC). For acidic conditions we determine from our ITC data an exothermal binding enthalpy of -40 kJ mol(-1). Increasing SDS/BLG molar ratios above 10 leads to a surface excess of SDS and thus to a charge reversal from a positive net charge with BLG as the dominating surface adsorbed species to a negatively charged layer with SDS as the dominating surface species. The latter is evidenced by a pronounced minimum in SFG intensities that is also accompanied by a phase change of O-H stretching bands due to a reorientation of H2O within the local electric field. This phase change which occurs at SDS/BLG molar ratio between 1 and 10 causes a polarity change in SFG intensities from BLG aromatic C-H stretching vibrations. Conclusions from SFG spectra are corroborated by ellipsometry which shows a dramatic increase in layer thicknesses at molar ratios where a charge reversal occurs. The formation of interfacial multilayers comprising SDS-BLG complexes is, thus, caused by cancellation of electrostatic interactions which leads to agglomeration at the interface. In contrast to pH 3.8, behavior of BLG-SDS mixtures at pH 6.7 is different due to repulsive electrostatic interactions between SDS and BLG which lead to a significantly reduced binding enthalpy of -17 kJ mol(-1). Finally, it has to be mentioned that

  20. Preliminary investigation of the elemental variation and diagenesis of a tabular uranium deposit, La Sal Mine, San Juan County, Utah

    USGS Publications Warehouse

    Brooks, Robert A.; Campbell, John A.

    1976-01-01

    Ore in the La Sal mine, San Juan County, Utah, occurs as a typical tabular-type uranium deposit of the-Colorado Plateau. Uranium-vanadium occurs in the Salt Wash Member of the Jurassic Morrison Formation. Chemical and petrographic analyses were used to determine elemental variation and diagenetic aspects across the orebody. Vanadium is concentrated in the dark clay matrix, which constitutes visible ore. Uranium content is greater above the vanadium zone. Calcium, carbonate carbon, and lead show greater than fifty-fold increase across the ore zone, whereas copper and organic carbon show only a several-fold increase. Large molybdenum concentrations are present in and above the tabular layer, and large selenium concentrations occur below the uranium zone within the richest vanadium zone. Iron is enriched in the vanadium horizon. Chromium is depleted from above the ore and strongly enriched below. Elements that vary directly with the vanadium content include magnesium, iron, selenium, zirconium, strontium, titanium, lead, boron, yttrium, and scandium. The diagenetic sequence is as follows: (1) formation of secondary quartz overgrowths as cement; (2) infilling and lining of remaining pores with amber opaline material; (3) formation of vanadium-rich clay matrix, which has replaced overgrowths as well as quartz grains; (4) replacement of overgrowths and detrital grains by calcite; (5) infilling of pores with barite and the introduction of pyrite and marcasite.

  1. A modified SUnSAL-TV algorithm for hyperspectral unmixing based on spatial homogeneity analysis

    NASA Astrophysics Data System (ADS)

    Yuqian, Wang; Zhenfeng, Shao; Lei, Zhang; Weixun, Zhou

    2014-03-01

    The sparse regression framework has been introduced by many works to solve the linear spectral unmixing problem due to the knowledge that a pixel is usually mixed by less endmembers compared with the endmembers in spectral libraries or the entire hyperspectral data sets. Traditional sparse unmixing techniques focus on analyzing the spectral properties of hyperspectral imagery without incorporating spatial information. But the integration of spatial information would be beneficial to promote the performance of the linear unmixing process. An algorithm called sparse unmixing via variable splitting augmented Lagrangian and total variation (SUnSAL-TV) adds a total variation spatial regularizer besides the sparsity-inducing regularizer to the final unmixing objective function. The total variation spatial regularization is helpful to promote the fractional abundance smoothness. However, the abundance smoothness varies in the image. In this paper, the spatial smoothness is estimated through homogeneity analysis. Then the spatial regularizer is weighted for each pixel by a homogeneity index. The modified algorithm, called homogeneity analysis based SUnSAL-TV (SUnSAL-TVH), integrates the spatial information with finer modelling of spatial smoothness and is supposed insensitive to the noise and more stable. Experiments on synthetic data sets are taken and indicate the validity of our algorithm.

  2. Sal-Site: Integrating new and existing ambystomatid salamander research and informational resources

    PubMed Central

    Smith, Jeramiah J; Putta, Srikrishna; Walker, John A; Kump, D Kevin; Samuels, Amy K; Monaghan, James R; Weisrock, David W; Staben, Chuck; Voss, S Randal

    2005-01-01

    Salamanders of the genus Ambystoma are a unique model organism system because they enable natural history and biomedical research in the laboratory or field. We developed Sal-Site to integrate new and existing ambystomatid salamander research resources in support of this model system. Sal-Site hosts six important resources: 1) Salamander Genome Project: an information-based web-site describing progress in genome resource development, 2) Ambystoma EST Database: a database of manually edited and analyzed contigs assembled from ESTs that were collected from A. tigrinum tigrinum and A. mexicanum, 3) Ambystoma Gene Collection: a database containing full-length protein-coding sequences, 4) Ambystoma Map and Marker Collection: an image and database resource that shows the location of mapped markers on linkage groups, provides information about markers, and provides integrating links to Ambystoma EST Database and Ambystoma Gene Collection databases, 5) Ambystoma Genetic Stock Center: a website and collection of databases that describe an NSF funded salamander rearing facility that generates and distributes biological materials to researchers and educators throughout the world, and 6) Ambystoma Research Coordination Network: a web-site detailing current research projects and activities involving an international group of researchers. Sal-Site is accessible at . PMID:16359543

  3. Re(V) and Re(III) complexes with sal2phen and triphenylphosphine: rearrangement, oxidation and reduction.

    PubMed

    Lane, Stephanie Renee; Sisay, Nebiat; Carney, Brett; Dannoon, Shorouk; Williams, Stephen; Engelbrecht, Hendrik Petrus; Barnes, Charles Leslie; Jurisson, Silvia Sabine

    2011-01-01

    Reactions of Re(V), tetradentate Schiff base complexes with tertiary phosphines have previously yielded both rearranged Re(V) and reduced Re(III) complexes. To further understand this chemistry, the rigid diiminediphenol (N(2)O(2)) Schiff base ligand sal(2)phen (N,N'-o-phenylenebis(salicylaldimine)) was reacted with (n-Bu(4)N)[ReOCl(4)] to yield trans-[ReOCl(sal(2)phen)] (1). On reaction with triphenylphosphine (PPh(3)), a rearranged Re(V) product cis-[ReO(PPh(3))(sal(2)phen*)]PF(6) (2), in which one of the imines was reduced to an amine during the reaction, and the reduced Re(III) products trans-[ReCl(PPh(3))(sal(2)phen)] (4) and trans-[Re(PPh(3))(2)(sal(2)phen)](+) (5) were isolated. Reaction of sal(2)phen with [ReCl(3)(PPh(3))(2)(CH(3)CN)] resulted in the isolation of [ReCl(2)(PPh(3))(2)(salphen)] (3). The compounds were characterized using standard spectroscopic methods, elemental analyses and single crystal X-ray crystallography. PMID:21079821

  4. Re(V) and Re(III) Complexes with Sal2phen and Triphenylphosphine: Rearrangement, Oxidation and Reduction

    PubMed Central

    Lane, Stephanie Renee; Sisay, Nebiat; Carney, Brett; Dannoon, Shorouk; Williams, Stephen; Engelbrecht, Hendrik Petrus; Barnes, Charles Leslie; Jurisson, Silvia Sabine

    2010-01-01

    Reactions of ReV, tetradentate Schiff base complexes with tertiary phosphines have previously yielded both rearranged ReV and reduced ReIII complexes. To further understand this chemistry, the rigid diiminediphenol (N2O2) Schiff base ligand sal2phen (N,N’-o-phenylenebis(salicylaldimine)) was reacted with (n-Bu4N)[ReOCl4] to yield trans-[ReOCl(sal2phen)] (1). On reaction with triphenylphosphine (PPh3), a rearranged ReV product cis-[ReO(PPh3)(sal2phen*)]PF6 (2), in which one of the imines was reduced to an amine during the reaction, and the reduced ReIII products trans-[ReCl(PPh3)(sal2phen)] (4) and trans- [Re(PPh3)2(sal2phen)]+ (5) were isolated. Reaction of sal2phen with [ReCl3(PPh3)2(CH3CN)] resulted in the isolation of [ReCl2(PPh3)2(salphen)] (3). The compounds were characterized using standard spectroscopic methods, elemental analyses and single crystal X-ray crystallography. PMID:21079821

  5. D-SAL and NAP: Two Peptides Sharing a SIP Domain.

    PubMed

    Gozes, Illana; Sragovich, Shlomo; Schirer, Yulie; Idan-Feldman, Anat

    2016-06-01

    NAPVSIPQ (NAP) and all D-amino acid SALLRSIPA (D-SAL) are neuroprotective peptides derived from activity-dependent neuroprotective protein (ADNP) and activity-dependent neurotrophic factor (ADNF), respectively. Both proteins were shown to protect against cognitive impairment, using different animal models and to increase neuronal survival following exposure to neurotoxins. NAP was extensively tested and found to increase microtubule stability, protect axonal transport, and inhibit apoptosis. Here, we aimed to further evaluate and correlate effects at the behavioral level, in a rat model of diabetes. Diabetes is primarily a metabolic disorder which presents secondary neurological manifestations. Diabetes induces peripheral nervous system damage which is translated into impaired sensory perception and is termed diabetic neuropathy. Diabetes-related central nervous system damage causes cognitive decline. The behavioral study aimed to evaluate the effect of NAP and D-SAL on peripheral neuropathy and cognitive decline. Peripheral neuropathy was tested by measuring the response to a thermal stimulus, and cognitive ability was measured by a social memory test and a spatial memory test using long- and short-term dependent tasks and a reference memory task. Results indicated an immediate sensory neuropathy in the diabetic model, which was prevented by both peptides and a later neuropathic phase, prevented only by NAP treatment. Cognitive tests revealed impaired performance in both social and spatial memory tests in the diabetes model. Each of the peptides improved different aspects of cognitive behavior, with NAP being more potent than D-SAL. Mechanistically, both NAP and SAL contain a SIP (SxIP) domain that has been shown to interact with microtubule end-binding proteins (EBs). Specifically, we have previously shown a direct interaction of NAP with EB1 and EB3; we have further shown an interaction of the NAP-derived 4 amino acid SKIP peptide with EB3, stimulating axonal

  6. A Study of Cold-Air Modification over the Gulf of Mexico Using In Situ Data and Mixed-Layer Modeling.

    NASA Astrophysics Data System (ADS)

    Liu, Qingfu; Lewis, John M.; Schneider, Jeanne M.

    1992-08-01

    The evolution of the mean characteristics of the marine boundary layer during cold-air outbreaks can be described with an integrated or slab model. In order to assess the practical applicability of this-type of model to flows over the Gulf of Mexico, we use the observations collected during the Gulf of Mexico Experiment (GUFMEX) by an instrumented National Oceanic and Atmospheric Administration (NOAA) P-3 aircraft and a Cross-chain Loran Atmospheric Sounding System (CLASS) onboard the U.S. Coast Guard vessel Salvia. The numerical results show that the model successfully reproduced the changes in mean characteristics of momentum, moisture, and temperature under unstable conditions. The largest differences between the predictions and measurements are 0.8°C for the potential temperature, 0.15 g kg1 for the specific humidity, 47 m for the mixed-layer height, and 1.5 m s1 for the horizontal velocity components. A sensitivity analysis shows that the modeled mixed-layer height is slightly sensitive to changes in the specified sea surface temperature, while the other mean characteristics are relatively insensitive to the input parameters. Based upon the results of this single case study, the slab model appears to be a promising approach to account for the moistening and heating processes at the air-sea interface during cold-air outbreaks over the Gulf of Mexico.

  7. Improvement of performance in low temperature solid oxide fuel cells operated on ethanol and air mixtures using Cu-ZnO-Al2O3 catalyst layer

    NASA Astrophysics Data System (ADS)

    Morales, M.; Espiell, F.; Segarra, M.

    2015-10-01

    Anode-supported single-chamber solid oxide fuel cells with and without Cu-ZnO-Al2O3 catalyst layers deposited on the anode support have been operated on ethanol and air mixtures. The cells consist of gadolinia-doped ceria electrolyte, Ni-doped ceria anode, and La0.6Sr0.4CoO3-δ-doped ceria cathode. Catalyst layers with different Cu-ZnO-Al2O3 ratios are deposited and sintered at several temperatures. Since the performance of single-chamber fuel cells strongly depends on catalytic properties of electrodes for partial oxidation of ethanol, the cells are electrochemically characterized as a function of the temperature, ethanol-air molar ratio and gas flow rate. In addition, catalytic activities of supported anode, catalytic layer-supported anode and cathode for partial oxidation of ethanol are analysed. Afterwards, the effect of composition and sintering temperature of catalyst layer on the cell performance are determined. The results indicate that the cell performance can be significantly enhanced using catalyst layers of 30:35:35 and 40:30:30 wt.% Cu-ZnO-Al2O3 sintered at 1100 °C, achieving power densities above 50 mW cm-2 under 0.45 ethanol-air ratio at temperatures as low as 450 °C. After testing for 15 h, all cells present a gradual loss of power density, without carbon deposition, which is mainly attributed to the partial re-oxidation of Ni at the anode.

  8. Observation studies on the influence of atmospheric boundary layer characteristics associate with air quality in dry season over the Pearl River Delta, China

    NASA Astrophysics Data System (ADS)

    Fan, Shaojia; Wu, Meng; Li, Haowen; Liao, Zhiheng; Fan, Qi; Zhu, Wei

    2016-04-01

    The characteristics of atmospheric boundary layer (ABL) is the very important factors influence on air quality in dry season over the Pearl River Delta (PRD), China. Based on the sounding data at six stations (Xinken,Dongguan, Sanshui, Nanhai, Shunde, and Heshan) which obtained from three times ABL experiments carried in dry season over PRD, the influence of wind and temperature vertical structure to the air quality over PRD has been studied with wind and temperature profiles, inversion layer, recirculation factor (RF), atmospheric boundary layer height (ABLH) and ventilation index (VI). It was found that the vertical wind of PRD could be divided in typical three layers according two wind shears appeared in 800 m and 1300 m. The thickness of calm or lower wind speed layer in pollution days was 500-1000m thicker than that of clean days, and its last time also much longer than that of clean days. The frequency of surface inversion in pollution days was about 35%,the mean thickness was about 100 m. With the influence of sea breeze, the frequency and thickness of surface inversion layer at Xinken station was a little lower than that in inland. Influenced by sea-land breezes and urban heat-island circulation, the RF of pollution days in coastal and urban area was quite smaller than that of clean days. During sea-land breezes days, the pollutants would be transported back to inland in nighttime with the influence of sea breeze, and resulted in 72.7% sea-land breezes was pollution days. The evolution of ABL was very typical in PRD during dry season. In pollution days, daily ABLH in PRD was lower than 500 m, daily VI was about 500-1500 m2/s. In clean days, daily VI was much larger than 2500 m2/s. An improved conceptual model of ABL influence on poor air quality and the parameters of the ABL characteristics associate with poor air quality in dry season over PRD had been summarized.

  9. Hourly air temperature driven using multi-layer perceptron and radial basis function networks in arid and semi-arid regions

    NASA Astrophysics Data System (ADS)

    Rezaeian-Zadeh, Mehdi; Zand-Parsa, Shahrookh; Abghari, Hirad; Zolghadr, Masih; Singh, Vijay P.

    2012-08-01

    This study employed two artificial neural network (ANN) models, including multi-layer perceptron (MLP) and radial basis function (RBF), as data-driven methods of hourly air temperature at three meteorological stations in Fars province, Iran. MLP was optimized using the Levenberg-Marquardt (MLP_LM) training algorithm with a tangent sigmoid transfer function. Both time series (TS) and randomized (RZ) data were used for training and testing of ANNs. Daily maximum and minimum air temperatures (MM) and antecedent daily maximum and minimum air temperatures (AMM) constituted the input for ANNs. The ANN models were evaluated using the root mean square error (RMSE), the coefficient of determination ( R 2) and the mean absolute error. The use of AMM led to a more accurate estimation of hourly temperature compared with the use of MM. The MLP-ANN seemed to have a higher estimation efficiency than the RBF ANN. Furthermore, the ANN testing using randomized data showed more accurate estimation. The RMSE values for MLP with RZ data using daily maximum and minimum air temperatures for testing phase were equal to 1.2°C, 1.8°C, and 1.7°C, respectively, at Arsanjan, Bajgah, and Kooshkak stations. The results of this study showed that hourly air temperature driven using ANNs (proposed models) had less error than the empirical equation.

  10. The performance of a two-layer biotrickling filter filled with new mixed packing materials for the removal of H2S from air.

    PubMed

    Chen, Yingwen; Wang, Xiaojun; He, Shuo; Zhu, Shemin; Shen, Shubao

    2016-01-01

    In the work described here, a two-layer biotrickling filter filled with new packing materials was used to remove H2S from air. The upper layer of the filter was packed with activated carbon-loaded polyurethane, whereas the lower layer was filled with modified organism-suspended fillers. The effects of inlet load, empty bed residence time (EBRT) from 79 s to 53 s, pH and contaminant starvation time were investigated. For loads of 15-50 g/(m(3) h), the average removal efficiency (RE) was higher than 96% under a consistent supply of pollutants. The critical elimination capacity was 39.95 g/(m(3) h) for an EBRT of 53 s with an RE of 99.9%. The two-layer BTF was capable of withstanding contaminant starvation periods for 1.5 d and 7 d with only a few hours of recovery time. The biodegradation kinetics was studied using Michaelis-Menten type equations under different EBRTs. At an EBRT of 66 s, the optimal kinetic constants rmax and Km were 333.3 g/(m(3) h) and 0.93 g/m(3), respectively. During the operation, the two-layer BTF performed well under various reasonable conditions. PMID:26397031

  11. Targeting of epidermal growth factor receptor (EGFR)-expressing tumor cells with sterically stabilized affibody liposomes (SAL).

    PubMed

    Beuttler, Julia; Rothdiener, Miriam; Müller, Dafne; Frejd, Fredrik Y; Kontermann, Roland E

    2009-06-01

    Affibody molecules are small and stable antigen-binding molecules derived from the B domain of protein A. We applied a bivalent, high-affinity epidermal growth factor receptor (EGFR)-specific affibody molecule for the generation of targeted PEGylated liposomes. These sterically stabilized affibody liposomes (SAL) were produced by chemical coupling of the cysteine-modified affibody molecule to maleimide-PEG(2000)-DSPE and subsequent insertion into PEGylated liposomes. These SAL showed strong and selective binding to EGFR-expressing tumor cell lines. Binding was dependent on the amount of inserted affibody molecule-lipid conjugates and could be blocked by soluble EGF. Approximately 30% of binding activity was still retained after 6 days of incubation in human plasma at 37 degrees C. Binding of SAL to cells led to efficient internalization of the liposomes. Using mitoxantrone-loaded liposomes, we observed for SAL, compared to untargeted liposomes, an enhanced cytotoxicity toward EGFR-expressing cells. In summary, we show that SAL can be easily prepared from affibody molecules and thus may be suitable for the development of carrier systems for targeted delivery of drugs. PMID:19435362

  12. A diagram of wind speed versus air-sea temperature difference to understand the dynamics of the marine atmospheric boundary layer off northwest Europe

    NASA Astrophysics Data System (ADS)

    Kettle, Anthony

    2015-04-01

    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 land-sea coastline discontinuities. In these offshore environments, the boundary layer processes are often best understood directly from time series measurements from measurement 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 updated results of 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 and offshore 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 North Sea illustrates how the wind characteristics vary spatially over large distances. 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.

  13. pH-induced structural changes in aqueous CTAB/NaSal solutions

    NASA Astrophysics Data System (ADS)

    Umeasiegbu, Chinedu; Krishnamoorti, Ramanan; Balakotaiah, Vemuri

    2015-03-01

    Cationic surfactants in the presence of hydrotropic salts exhibit pH-sensitive changes to rheological properties and can thus be utilized in ensuring effective stimulation of heterogeneous carbonate reservoirs. In this study, we investigate the pH-induced changes in microstructure and viscoelasticity of aqueous solutions of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal), and their dependence on temperature, NaSal-to-CTAB ratio (CS/CD) and CTAB concentration (CD). It was observed that the solutions can be switched between gel-like (viscoelastic) and fluid-like (non-viscoelastic) behavior over a narrow pH range, and that the transition pH and associated change in viscoelasticity were strongly dependent on CS/CD. Dynamic light scattering and small-angle neutron scattering results revealed a hitherto unseen re-entrant transition in which micelles transition from cylindrical to spherical micelles but revert to flexible cylindrical micelles on reduction in pH. Our observations suggest that in addition to the well described electrostatic and hydrophobic interactions in cationic surfactant - hydrotrope mixtures, the pH-induced microstructural changes are governed by complementary cation- π interactions and hydrogen bonding.

  14. An Effective On-line Polymer Characterization Technique by Using SALS Image Processing Software and Wavelet Analysis

    PubMed Central

    Xian, Guang-ming; Qu, Jin-ping; Zeng, Bi-qing

    2008-01-01

    This paper describes an effective on-line polymer characterization technique by using small-angle light-scattering (SALS) image processing software and wavelet analysis. The phenomenon of small-angle light scattering has been applied to give information about transparent structures on morphology. Real-time visualization of various scattered light image and light intensity matrices is performed by the optical image real-time processing software for SALS. The software can measure the signal intensity of light scattering images, draw the frequency-intensity curves and the amplitude-intensity curves to indicate the variation of the intensity of scattered light in different processing conditions, and estimate the parameters. The current study utilizes a one-dimensional wavelet to delete noise from the original SALS signal and estimate the variation trend of maximum intensity area of the scattered light. So, the system brought the qualitative analysis of the structural information of transparent film success. PMID:19229343

  15. Forced Boundary-Layer Transition on X-43 (Hyper-X) in NASA LaRC 31-Inch Mach 10 Air Tunnel

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; DiFulvio, Michael; Kowalkowski, Matthew K.

    2000-01-01

    Aeroheating and boundary layer transition characteristics for the X-43 (Hyper-X) configuration have been experimentally examined in the Langley 31-Inch Mach 10 Air Tunnel. Global surface heat transfer distributions, and surface streamline patterns were measured on a 0.333-scale model of the Hyper-X forebody. Parametric variations include angles-of-attack of 0-deg, 2-deg, 3-deg, and 4-deg; Reynolds numbers based on model length of 1.2 to 5.1 million; and inlet cowl door both open and closed. The effects of discrete roughness elements on the forebody boundary layer, which included variations in trip configuration and height, were investigated. This document is intended to serve as a release of preliminary data to the Hyper-X program; analysis is limited to observations of the experimental trends in order to expedite dissemination.

  16. Forced Boundary-Layer Transition on X-43 (Hyper-X) in NASA LaRC 20-Inch Mach 6 Air Tunnel

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; DiFulvio, Michael; Kowalkowski, Matthew K.

    2000-01-01

    Aeroheating and boundary layer transition characteristics for the X-43 (Hyper-X) configuration have been experimentally examined in the Langley 20-Inch Mach 6 Air Tunnel. Global surface heat transfer distributions, and surface streamline patterns were measured on a 0.333-scale model of the Hyper-X forebody. Parametric variations include angles-of-attack of 0-deg, 2-deg, and 4-deg; Reynolds numbers based on model length of 1.2 to 15.4 million; and inlet cowl door both open and closed. The effects of discrete roughness elements on the forebody boundary layer, which included variations in trip configuration and height, were investigated. This document is intended to serve as a release of preliminary data to the Hyper-X program; analysis is limited to observations of the experimental trends in order to expedite dissemination.

  17. A Numerical Study of Tropical Sea-Air Interactions Using a Cloud Resolving Model Coupled with an Ocean Mixed-Layer Model

    NASA Technical Reports Server (NTRS)

    Shie, Chung-Lin; Tao, Wei-Kuo; Johnson, Dan; Simpson, Joanne; Li, Xiaofan; Sui, Chung-Hsiung; Einaudi, Franco (Technical Monitor)

    2001-01-01

    Coupling a cloud resolving model (CRM) with an ocean mixed layer (OML) model can provide a powerful tool for better understanding impacts of atmospheric precipitation on sea surface temperature (SST) and salinity. The objective of this study is twofold. First, by using the three dimensional (3-D) CRM-simulated (the Goddard Cumulus Ensemble model, GCE) diabatic source terms, radiation (longwave and shortwave), surface fluxes (sensible and latent heat, and wind stress), and precipitation as input for the OML model, the respective impact of individual component on upper ocean heat and salt budgets are investigated. Secondly, a two-way air-sea interaction between tropical atmospheric climates (involving atmospheric radiative-convective processes) and upper ocean boundary layer is also examined using a coupled two dimensional (2-D) GCE and OML model. Results presented here, however, only involve the first aspect. Complete results will be presented at the conference.

  18. Heat and mass transfer in a dissociated laminar boundary layer of air with consideration of the finite rate of chemical reaction

    NASA Technical Reports Server (NTRS)

    Oyegbesan, A. O.; Algermissen, J.

    1986-01-01

    A numerical investigation of heat and mass transfer in a dissociated laminar boundary layer of air on an isothermal flat plate is carried out for different degrees of cooling of the wall. A finite-difference chemical model is used to study elementary reactions involving NO2 and N2O. The analysis is based on equations of continuity, momentum, energy, conservation and state for the two-dimensional viscous flow of a reacting multicomponent mixtures. Attention is given to the effects of both catalyticity and noncatalyticity of the wall.

  19. Efficient, air-stable colloidal quantum dot solar cells encapsulated using atomic layer deposition of a nanolaminate barrier

    SciTech Connect

    Ip, Alexander H.; Labelle, André J.; Sargent, Edward H.

    2013-12-23

    Atomic layer deposition was used to encapsulate colloidal quantum dot solar cells. A nanolaminate layer consisting of alternating alumina and zirconia films provided a robust gas permeation barrier which prevented device performance degradation over a period of multiple weeks. Unencapsulated cells stored in ambient and nitrogen environments demonstrated significant performance losses over the same period. The encapsulated cell also exhibited stable performance under constant simulated solar illumination without filtration of harsh ultraviolet photons. This monolithically integrated thin film encapsulation method is promising for roll-to-roll processed high efficiency nanocrystal solar cells.

  20. Aerosol-cloud-precipitation interactions in the trade wind boundary layer

    NASA Astrophysics Data System (ADS)

    Jung, Eunsil

    This dissertation includes an overview of aerosol, cloud, and precipitation properties associated with shallow marine cumulus clouds observed during the Barbados Aerosol Cloud Experiment (BACEX, March-April 2010) and a discussion of their interactions. The principal observing platform for the experiment was the Cooperative Institute for Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter (TO) research aircraft that was equipped with aerosol, cloud, and precipitation probes, standard meteorological instruments, and a up-looking cloud radar. The temporal variations and vertical distributions of aerosols observed on the 15 flights show a wide range of aerosol conditions that include the most intense African dust event observed at the Barbados surface site during all of 2010. An average CCN varied from 50 cm-3 to 800 cm -3 at super-saturation of 0.6 %, for example. The 10-day backward trajectories show that three distinctive air masses (originality of air mass as well as the vertical structure) dominate over the Eastern Caribbean (e.g., typical maritime air mass, Saharan Air Layer (SAL), Middle latitude dry air) with characteristic aerosol vertical structures. Many clouds in various phases of growth during BACEX are sampled. The maximum cloud depth observed is about less than 3 km and in most of the clouds is less than 1 km. Two types of precipitation features were observed for the shallow marine cumulus clouds with different impacts on boundary layer. In one, precipitation shafts are observed to emanate from the cloud base with evaporation in the sub-cloud layer (stabilize the sub-cloud layer). In the other, precipitation shafts emanate mainly near the cloud top on the downshear side of the cloud and evaporate in the cloud layer, leading to destabilizing the cloud layer and providing moisture to the layer. Only 42-44 % of clouds sampled were purely non-precipitating throughout the clouds; the remainder of the clouds showed precipitation somewhere in the cloud

  1. A SAL1 Loss-of-Function Arabidopsis Mutant Exhibits Enhanced Cadmium Tolerance in Association with Alleviation of Endoplasmic Reticulum Stress.

    PubMed

    Xi, Hongmei; Xu, Hua; Xu, Wenxiu; He, Zhenyan; Xu, Wenzhong; Ma, Mi

    2016-06-01

    SAL1, as a negative regulator of stress response signaling, has been studied extensively for its role in plant response to environmental stresses. However, the role of SAL1 in cadmium (Cd) stress response and the underlying mechanism is still unclear. Using an Arabidopsis thaliana loss-of-function mutant of SAL1, we assessed Cd resistance and further explored the Cd toxicity mechanism through analysis of the endoplasmic reticulum (ER) stress response. The loss of SAL1 function greatly improved Cd tolerance and significantly attenuated ER stress in Arabidopsis. Exposure to Cd induced an ER stress response in Arabidopsis as evidenced by unconventional splicing of AtbZIP60 and up-regulation of ER stress-responsive genes. Damage caused by Cd was markedly reduced in the ER stress response double mutant bzip28 bzip60 or by application of the ER stress-alleviating chemical agents, tauroursodeoxycholic acid (TUDCA) and 4-phenyl butyric acid (4-PBA), in wild-type plants. The Cd-induced ER stress in Arabidopsis was also alleviated by loss of function of SAL1. These results identified SAL1 as a new component mediating Cd toxicity and established the role of the ER stress response in Cd toxicity. Additionally, the attenuated ER stress in the sal1 mutant might also shed new light on the mechanism of diverse abiotic stress resistance in the SAL1 loss-of-function mutants. PMID:27044671

  2. The China Clipper - Fast advective transport of radon-rich air from the Asian boundary layer to the upper troposphere near California

    NASA Technical Reports Server (NTRS)

    Kritz, Mark A.; Le Roulley, Jean-Claude; Danielsen, Edwin F.

    1990-01-01

    A series of upper tropospheric radon concentration measurements made over the eastern Pacific and west coast of the U.S. during the summers of 1983 and 1984 has revealed the occurrence of unexpectedly high radon concentrations for 9 of the 61 measurements. A frequency distribution plot of the set of 61 observations shows a distinct bimodal distribution, with approximately 2/5 of the observations falling close to 1 pCi/SCM, and 3/5 falling in a high concentration mode centered at about 11 pCi/SCM. Trajectory and synoptic analyses for two of the flights on which such high radon concentrations were observed indicate that this radon-rich air originated in the Asian boundary layer, ascended in cumulus updrafts, and was carried eastward in the fast moving air on the anticyclonic side of the upper tropospheric jet. The results suggest that the combination of rapid vertical transport from the surface boundary layer to the upper troposphere, followed by rapid horizontal transport eastward represents an efficient mode of long-transport for other, chemically reactive atmospheric trace constituents.

  3. A morphology, porosity and surface conductive layer optimized MnCo2O4 microsphere for compatible superior Li(+) ion/air rechargeable battery electrode materials.

    PubMed

    Yun, Young Jun; Kim, Jin Kyu; Ju, Ji Young; Unithrattil, Sanjith; Lee, Sun Sook; Kang, Yongku; Jung, Ha-Kyun; Park, Jin-Seong; Im, Won Bin; Choi, Sungho

    2016-03-15

    Uniform surface conductive layers with porous morphology-conserved MnCo2O4 microspheres are successfully synthesized, and their electrochemical performances are thoroughly investigated. It is found that the microwave-assisted hydrothermally grown MnCo2O4 using citric acid as the carbon source shows a maximum Li(+) ion lithiation/delithiation capacity of 501 mA h g(-1) at 500 mA g(-1) with stable capacity retention. Besides, the given microsphere compounds are effectively activated as air cathode catalysts in Li-O2 batteries with reduced charge overpotentials and improved cycling performance. We believe that such an affordable enhanced performance results from the appropriate quasi-hollow nature of MnCo2O4 microspheres, which can effectively mitigate the large volume change of electrodes during Li(+) migration and/or enhance the surface transport of the LiOx species in Li-air batteries. Thus, the rationally designed porous media for the improved Li(+) electrochemical reaction highlight the importance of the 3D macropores, the high specific area and uniformly overcoated conductive layer for the promising Li(+) redox reaction platforms. PMID:26877264

  4. Ten Years of OMI Observations: A Unique Contribution to Air Quality, Ozone Layer and Climate Research from Space.

    NASA Astrophysics Data System (ADS)

    Levelt, P.; Veefkind, J. P.; Bhartia, P. K.; Joiner, J.; Tamminen, J.

    2014-12-01

    On July 15, 2004 the Ozone Monitoring Instrument (OMI) was successfully launched on board of NASA's EOS-Aura spacecraft. OMI is the first of a new generation of UV/VIS nadir solar backscatter imaging spectrometers, which provides nearly global coverage in one day with an unprecedented spatial resolution of 13 x 24 km2. OMI measures solar irradiance and Earth radiances in the wavelength range of 270 to 500 nm with a spectral resolution of about 0.5 nm. OMI is designed and built by the Netherlands and Finland, and is also a third party mission of ESA. The major step that was made in the OMI instrument compared to its predecessors is the use of 2-dimensional detector arrays (CCDs) in a highly innovative small optical design. These innovations enable the combination of a high spatial resolution and a good spectral resolution with daily global coverage. OMI measures a range of trace gases (O3, NO2, SO2, HCHO, BrO, OClO, H2O), clouds and aerosols. Albeit OMI is already 5 years over its design lifetime, the instrument is still fully operational. The successor of OMI is TROPOMI (TROPOspheric Monitoring Instrument) on the Copernicus Sentinel-5 precursor mission, planned for launch in 2016. OMI's unique capabilities rely in measuring tropospheric trace gases with a small footprint and daily global coverage. The unprecedented spatial resolution of the instrument revealed for the first time tropospheric pollution maps on a daily basis with urban scale resolution leading to improved air quality forecasts. The OMI measurements also improve our understanding of air quality and the interaction between air quality and climate change by combining measurements of air pollutants and aerosols. In recent years the data are also used for obtaining high-resolution global emission maps using inverse modelling or related techniques, challenging the bottom-up inventories based emission maps. In addition to scientific research, OMI also contributes to several operational services, including

  5. Testing a detailed biophysical parameterization for land-air exchange in a high-resolution boundary-layer model

    NASA Technical Reports Server (NTRS)

    Argentini, S.; Wetzel, P. J.; Karyampudi, V. M.

    1992-01-01

    This study modifies the 1D PBL model of Zhang and Anthes (1982) to account more explicitly for the effects of a vegetation layer. New equations for the latent, sensible, and ground heat fluxes, reformulated in terms of vegetation parameters are substituted into the model. The model produces good agreement with observations over a wide range of conditions: for wet, high-vegetation conditions, and for dry, low-vegetation conditions in both the winter and the summer.

  6. Measurements of Pb-212 and Pb-214 in surface air around Lake Michigan and their implications for atmospheric boundary layer mixing

    NASA Astrophysics Data System (ADS)

    Aquino, Nadja Wackerling

    1997-10-01

    The dynamics of the atmospheric boundary layer are a result of turbulence generated at the Earth's surface. The extent of mixing in the boundary layer is studied by using radionuclides as tracers under different conditions such as: wind direction dependent on passing synoptic systems, upwind and downwind lake shore sites, urban versus rural setting, and urban setting at two different altitudes. Data were collected by high volume air samplers at each site, which filtered air for day and night intervals several days in a row. The filters were placed in a GeLe detector and gamma rays of 212Pb and 214Pb decays were counted. From these measurements, the concentrations of 212Pb and 214Pb in the sampled air were determined. Among the types of radionuclide behavior are diurnal variation in activities, synoptic-scale variation, variation due to different surface roughness characteristics and position with respect to the wind at the lake shore, and limited variation in activity at high altitude at the urban site. A series of one dimensional models were developed to interpret the data. The horizontal advection model predicted the effect on 212Pb and 214Pb activities of advecting air over a 100 km zero source region at constant velocity. 212Pb activities decrease substantially for velocities greater than 1 m/s, whereas 214Pb does not decrease much until velocities reach 100 m/s. The vertical diffusion model predicted 212Pb and 214Pb vertical profiles for different vertical diffusivities, κ z. A one order of magnitude change in κ z produces a /sqrt[10] change in activity in surface air. The results of both models are equivalent for 212Pb activities. Comparing 212Pb and 214Pb, vertical mixing affects both radionuclides similarly, but horizontal advection fractionates the two radionuclides. The diurnal box models predict activities an order of magnitude lower than the steady state models, in close agreement with observations. Furthermore, an order of magnitude increase can

  7. The Turbulent Boundary Layer Near the Air-Water Interface on a Surface-Piercing Flat Plate

    NASA Astrophysics Data System (ADS)

    Washuta, Nathan; Masnadi, Naeem; Duncan, James H.

    2015-11-01

    Turbulent fluctuations in the vicinity of the water free surface along a flat, vertically oriented surface-piercing plate are studied experimentally using a laboratory-scale experiment. In this experiment, a meter-wide stainless steel belt travels horizontally in a loop around two rollers with vertically oriented axes, which are separated by 7.5 meters. This belt device is mounted inside a large water tank with the water level set just below the top edge of the belt. The belt, rollers, and supporting frame are contained within a sheet metal box to keep the device dry except for one 6-meter-long straight test section between rollers. The belt is launched from rest with a 3- g acceleration in order to quickly reach steady state velocity. This creates a temporally evolving boundary layer analogous to the spatially evolving boundary layer created along a flat-sided ship moving at the same velocity, with a length equivalent to the length of belt that has passed the measurement region since the belt motion began. Cinematic Stereo PIV measurements are performed in planes parallel to the free surface by imaging the flow from underneath the tank in order to study the modification of the boundary layer flow field due to the effects of the water free surface. The support of the Office of Naval Research under grant N000141110029 is gratefully acknowledged.

  8. Hepatoprotective Activity of Herbal Composition SAL, a Standardize Blend Comprised of Schisandra chinensis, Artemisia capillaris, and Aloe barbadensis.

    PubMed

    Yimam, Mesfin; Jiao, Ping; Moore, Breanna; Hong, Mei; Cleveland, Sabrina; Chu, Min; Jia, Qi; Lee, Young-Chul; Kim, Hyun-Jin; Nam, Jeong-Bum; Kim, Mi-Ran; Hyun, Eu-Jin; Jung, Gayoung; Do, Seon Gil

    2016-01-01

    Some botanicals have been reported to possess antioxidative activities acting as scavengers of free radicals rendering their usage in herbal medicine. Here we describe the potential use of "SAL," a standardized blend comprised of three extracts from Schisandra chinensis, Artemisia capillaris, and Aloe barbadensis, in mitigating chemically induced acute liver toxicities. Acetaminophen and carbon tetrachloride induced acute liver toxicity models in mice were utilized. Hepatic functional tests from serum collected at T24 and hepatic glutathione and superoxide dismutases from liver homogenates were evaluated. Histopathology analysis and merit of blending 3 standardized extracts were also confirmed. Statistically significant and dose-correlated inhibitions in serum ALT ranging from 52.5% (p = 0.004) to 34.6% (p = 0.05) in the APAP and 46.3% (p < 0.001) to 29.9% (p = 0.02) in the CCl4 models were observed for SAL administered at doses of 400-250 mg/kg. Moreover, SAL resulted in up to 60.6% and 80.2% reductions in serums AST and bile acid, respectively. The composition replenished depleted hepatic glutathione in association with an increase of hepatic superoxide dismutase. Unexpected synergistic protection from liver damage was also observed. Therefore, the composition SAL could be potentially utilized as an effective hepatic-detoxification agent for the protection from liver damage. PMID:27066270

  9. 76 FR 9403 - Finding That the Lebanese Canadian Bank SAL Is a Financial Institution of Primary Money...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-17

    ... countermeasures, see 68 FR 18917 (April 17, 2003) (proposing special measures against Nauru). \\3\\ Section 5318A(a... of Primary Money Laundering Concern AGENCY: Financial Crimes Enforcement Network, Treasury (``FinCEN... for concluding that the Lebanese Canadian Bank SAL (``LCB'') is a financial institution of...

  10. Impact of LbSapSal Vaccine in Canine Immunological and Parasitological Features before and after Leishmania chagasi-Challenge.

    PubMed

    Resende, Lucilene Aparecida; Aguiar-Soares, Rodrigo Dian de Oliveira; Gama-Ker, Henrique; Roatt, Bruno Mendes; Mendonça, Ludmila Zanandreis de; Alves, Marina Luiza Rodrigues; Silveira-Lemos, Denise da; Corrêa-Oliveira, Rodrigo; Martins-Filho, Olindo Assis; Araújo, Márcio Sobreira Silva; Fujiwara, Ricardo Toshio; Gontijo, Nelder Figueiredo; Reis, Alexandre Barbosa; Giunchetti, Rodolfo Cordeiro

    2016-01-01

    Dogs represent the most important domestic reservoir of L. chagasi (syn. L. infantum). A vaccine against canine visceral leishmaniasis (CVL) would be an important tool for decreasing the anxiety related to possible L. chagasi infection and for controlling human visceral leishmaniasis (VL). Because the sand fly salivary proteins are potent immunogens obligatorily co-deposited during transmission of Leishmania parasites, their inclusion in an anti-Leishmania vaccine has been investigated in past decades. We investigated the immunogenicity of the "LbSapSal" vaccine (L. braziliensis antigens, saponin as adjuvant, and Lutzomyia longipalpis salivary gland extract) in dogs at baseline (T0), during the post-vaccination protocol (T3rd) and after early (T90) and late (T885) times following L. chagasi-challenge. Our major data indicated that immunization with "LbSapSal" is able to induce biomarkers characterized by enhanced amounts of type I (tumor necrosis factor [TNF]-α, interleukin [IL]-12, interferon [IFN]-γ) cytokines and reduction in type II cytokines (IL-4 and TGF-β), even after experimental challenge. The establishment of a prominent pro-inflammatory immune response after "LbSapSal" immunization supported the increased levels of nitric oxide production, favoring a reduction in spleen parasitism (78.9%) and indicating long-lasting protection against L. chagasi infection. In conclusion, these results confirmed the hypothesis that the "LbSapSal" vaccination is a potential tool to control the Leishmania chagasi infection. PMID:27556586

  11. Hepatoprotective Activity of Herbal Composition SAL, a Standardize Blend Comprised of Schisandra chinensis, Artemisia capillaris, and Aloe barbadensis

    PubMed Central

    Yimam, Mesfin; Jiao, Ping; Moore, Breanna; Hong, Mei; Cleveland, Sabrina; Chu, Min; Jia, Qi; Lee, Young-Chul; Kim, Hyun-Jin; Nam, Jeong-Bum; Kim, Mi-Ran; Hyun, Eu-Jin; Jung, Gayoung; Do, Seon Gil

    2016-01-01

    Some botanicals have been reported to possess antioxidative activities acting as scavengers of free radicals rendering their usage in herbal medicine. Here we describe the potential use of “SAL,” a standardized blend comprised of three extracts from Schisandra chinensis, Artemisia capillaris, and Aloe barbadensis, in mitigating chemically induced acute liver toxicities. Acetaminophen and carbon tetrachloride induced acute liver toxicity models in mice were utilized. Hepatic functional tests from serum collected at T24 and hepatic glutathione and superoxide dismutases from liver homogenates were evaluated. Histopathology analysis and merit of blending 3 standardized extracts were also confirmed. Statistically significant and dose-correlated inhibitions in serum ALT ranging from 52.5% (p = 0.004) to 34.6% (p = 0.05) in the APAP and 46.3% (p < 0.001) to 29.9% (p = 0.02) in the CCl4 models were observed for SAL administered at doses of 400–250 mg/kg. Moreover, SAL resulted in up to 60.6% and 80.2% reductions in serums AST and bile acid, respectively. The composition replenished depleted hepatic glutathione in association with an increase of hepatic superoxide dismutase. Unexpected synergistic protection from liver damage was also observed. Therefore, the composition SAL could be potentially utilized as an effective hepatic-detoxification agent for the protection from liver damage. PMID:27066270

  12. Thin air-plasma-treated alkali fluoride layers for improved hole extraction in copper phthalocyanine/C70-based solar cells

    SciTech Connect

    Xiao, Teng; Cui, Weipan; Cai, Min; Liu, Rui; Anderegg, James W.; Shinar, Joseph; Shinar, Ruth

    2012-03-12

    Alkali fluorides, mostly LiF and CsF, are well-known to improve electron injection/extraction in organic light-emitting diodes (OLEDs) and organic solar cells (OSCs). They are also utilized, though to a lesser extent, for hole injection in OLEDs. Here we demonstrate a new role for such fluorides in enhancing OSCs’ hole extraction.We show that an ultrathin air-plasmatreated alkali fluoride layer between the indium tin oxide (ITO) anode and the active layer in copper phthalocyanine ðCuPcÞ∕C70-based OSCs increases the short circuit current by up to ∼17% for cells with LiF and ∼7% for cells with NaF or CsF. The effects of the fluoride layer thickness and treatment duration were evaluated, as were OSCs with oxidized and plasma-treated Li and UV-ozone treated LiF. Measurements included current voltage, absorption, external quantum efficiency (EQE), atomic force microscopy, and x-ray photoelectron spectroscopy, which showed the presence of alkali atoms F and O at the treated ITO/fluoride surface. The EQE of optimized devices with LiF increased at wavelengths >560 nm, exceeding the absorption increase. Overall, the results indicate that the improved performance is due largely to enhanced hole extraction, possibly related to improved energy-level alignment at the fluorinated ITO/CuPc interface, reduced OSC series resistance, and in the case of LiF, improved absorption.

  13. Solutal Marangoni instability in a binary liquid layer evaporating into air: the importance of transients in the gas for highly unstable cases

    NASA Astrophysics Data System (ADS)

    Machrafi, Hatim; Rednikov, Alexey; Colinet, Pierre; Dauby, Pierre

    2012-11-01

    This study considers an evaporating horizontal binary-liquid layer (aqueous solution of ethanol; mass fraction 0.1) in contact with air with an imposed transfer distance. Fully transient and horizontally homogeneous solutions for the reference state are first calculated. Then, the linear stability of these solutions is studied using the frozen-time approach. Solutal and thermal Rayleigh-Bénard-Marangoni instabilities are taken into account together with the Soret effect, although the solutal Marangoni mechanism appeared to be the most important one. Considering several gas-to-liquid thickness ratios (H) , we calculate the critical times for the instability onset in a liquid layer of a given thickness. We also uncover the minimum liquid thicknesses under which no instability can ever occur. We subsequently observe that two distinctly different types of minimum thicknesses exist depending on H, examining each one of them. Then a closed-form analysis of the instability at small times has been developed. Finally, it has also been observed that, regardless of the gas-to-liquid thickness ratio, an asymptotic value of the critical time exists as the liquid layer increases, this critical time being approximately 1 μs.

  14. Experimental Study of the Morphology and Dynamics of Gas-Laden Layers Under the Anodes in an Air-Water Model of Aluminum Reduction Cells

    NASA Astrophysics Data System (ADS)

    Vékony, Klára; Kiss, László I.

    2012-10-01

    The bubble layer formed under an anode and the bubble-induced flow play a significant role in the aluminum electrolysis process. The bubbles covering the anode bottom reduce the efficient surface that can carry current. In our experiments, we filmed and studied the bubble layer under the anode in a real-size air-water electrolysis cell model. Three different flow regimes were found depending on the gas generation rate. The covering factor was found to be proportional to the gas generation rate and inversely proportional to the angle of inclination. A correlation between the average height of the entire bubble layer and the position under the anode was determined. From this correlation and the measured contact sizes, the volume of the accumulated gas was calculated. The sweeping effect of large bubbles was observed. Moreover, the small bubbles under the inner edge of the anode were observed to move backward as a result of the escape of huge gas pockets, which means large momentum transport occurs in the bath.

  15. Senstitivity analysis of horizontal heat and vapor transfer coefficients for a cloud-topped marine boundary layer during cold-air outbreaks. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Chang, Y. V.

    1986-01-01

    The effects of external parameters on the surface heat and vapor fluxes into the marine atmospheric boundary layer (MABL) during cold-air outbreaks are investigated using the numerical model of Stage and Businger (1981a). These fluxes are nondimensionalized using the horizontal heat (g1) and vapor (g2) transfer coefficient method first suggested by Chou and Atlas (1982) and further formulated by Stage (1983a). In order to simplify the problem, the boundary layer is assumed to be well mixed and horizontally homogeneous, and to have linear shoreline soundings of equivalent potential temperature and mixing ratio. Modifications of initial surface flux estimates, time step limitation, and termination conditions are made to the MABL model to obtain accurate computations. The dependence of g1 and g2 in the cloud topped boundary layer on the external parameters (wind speed, divergence, sea surface temperature, radiative sky temperature, cloud top radiation cooling, and initial shoreline soundings of temperature, and mixing ratio) is studied by a sensitivity analysis, which shows that the uncertainties of horizontal transfer coefficients caused by changes in the parameters are reasonably small.

  16. Sea level changes during the last and present interglacials in Sal Island (Cape Verde archipelago)

    NASA Astrophysics Data System (ADS)

    Zazo, C.; Goy, J. L.; Hillaire-Marcel, C.; Dabrio, C. J.; González-Delgado, J. A.; Cabero, A.; Bardají, T.; Ghaleb, B.; Soler, V.

    2010-07-01

    Last interglacial and Holocene deposits are particularly well developed in the southern parts of Sal Island (Cape Verde Archipelago). They primarily consist of low-elevation (≤ 2 m above sea level [a.s.l.]) marine deposits made of a basal conglomerate embedded in carbonate mud, passing upwards to calcarenites. All deposits contain an abundant fauna with corals, algae and molluscs with Strombus latus Gmelin and accompanying warm water species of the "Senegalese" fauna. Small scale geomorphological mapping with detailed morphosedimentary analysis revealed lateral facies changes and imbricate (offlapping) structures that suggest small-scale oscillations of paleo-sealevels during high sea stand intervals. U-series measurements (in coral fragments) allowed unequivocal identification of Marine Isotope Substage (MIS) 5.5 units, but were not precise enough to date the sea level oscillations of the interval. However, geomorphological data and sedimentary facies analysis suggest a double sea level highstand during the peak of the last interglacial. MIS 5.5 age deposits occur at Sal and the Canary Islands at low topographic elevations, between 1 and 2 masl. However, these values are lower than the elevations measured for the correlative terraces outcropping at the western tropical Atlantic islands, widely considered to be tectonically stable. Combining the results in this paper with earlier investigations of the "Senegalese" fauna distribution as far north as the Mediterranean basin, it is suggested that the last-interglacial oceanic temperatures in this basin, as well as the temperatures in other islands of the Eastern Atlantic and the coasts of Morocco, were warmer than modern temperatures.

  17. Insights into an Optimization of Plasmodium vivax Sal-1 In Vitro Culture: The Aotus Primate Model

    PubMed Central

    Obaldía, Nicanor; Nuñez, Marlon; Dutary, Sahir; Lim, Caeul; Barnes, Samantha; Kocken, Clemens H. M.; Duraisingh, Manoj T.; Adams, John H.; Pasini, Erica M.

    2016-01-01

    Malaria is one of the most significant tropical diseases, and of the Plasmodium species that cause human malaria, P. vivax is the most geographically widespread. However, P. vivax remains a relatively neglected human parasite since research is typically limited to laboratories with direct access to parasite isolates from endemic field settings or from non-human primate models. This restricted research capacity is in large part due to the lack of a continuous P. vivax in vitro culture system, which has hampered the ability for experimental research needed to gain biological knowledge and develop new therapies. Consequently, efforts to establish a long-term P. vivax culture system are confounded by our poor knowledge of the preferred host cell and essential nutrients needed for in vitro propagation. Reliance on very heterogeneous P. vivax field isolates makes it difficult to benchmark parasite characteristics and further complicates development of a robust and reliable culture method. In an effort to eliminate parasite variability as a complication, we used a well-defined Aotus-adapted P. vivax Sal-1 strain to empirically evaluate different short-term in vitro culture conditions and compare them with previous reported attempts at P. vivax in vitro culture Most importantly, we suggest that reticulocyte enrichment methods affect invasion efficiency and we identify stabilized forms of nutrients that appear beneficial for parasite growth, indicating that P. vivax may be extremely sensitive to waste products. Leuko-depletion methods did not significantly affect parasite development. Formatting changes such as shaking and static cultures did not seem to have a major impact while; in contrast, the starting haematocrit affected both parasite invasion and growth. These results support the continued use of Aotus-adapted Sal-1 for development of P. vivax laboratory methods; however, further experiments are needed to optimize culture conditions to support long-term parasite

  18. Insights into an Optimization of Plasmodium vivax Sal-1 In Vitro Culture: The Aotus Primate Model.

    PubMed

    Shaw-Saliba, Kathryn; Thomson-Luque, Richard; Obaldía, Nicanor; Nuñez, Marlon; Dutary, Sahir; Lim, Caeul; Barnes, Samantha; Kocken, Clemens H M; Duraisingh, Manoj T; Adams, John H; Pasini, Erica M

    2016-07-01

    Malaria is one of the most significant tropical diseases, and of the Plasmodium species that cause human malaria, P. vivax is the most geographically widespread. However, P. vivax remains a relatively neglected human parasite since research is typically limited to laboratories with direct access to parasite isolates from endemic field settings or from non-human primate models. This restricted research capacity is in large part due to the lack of a continuous P. vivax in vitro culture system, which has hampered the ability for experimental research needed to gain biological knowledge and develop new therapies. Consequently, efforts to establish a long-term P. vivax culture system are confounded by our poor knowledge of the preferred host cell and essential nutrients needed for in vitro propagation. Reliance on very heterogeneous P. vivax field isolates makes it difficult to benchmark parasite characteristics and further complicates development of a robust and reliable culture method. In an effort to eliminate parasite variability as a complication, we used a well-defined Aotus-adapted P. vivax Sal-1 strain to empirically evaluate different short-term in vitro culture conditions and compare them with previous reported attempts at P. vivax in vitro culture Most importantly, we suggest that reticulocyte enrichment methods affect invasion efficiency and we identify stabilized forms of nutrients that appear beneficial for parasite growth, indicating that P. vivax may be extremely sensitive to waste products. Leuko-depletion methods did not significantly affect parasite development. Formatting changes such as shaking and static cultures did not seem to have a major impact while; in contrast, the starting haematocrit affected both parasite invasion and growth. These results support the continued use of Aotus-adapted Sal-1 for development of P. vivax laboratory methods; however, further experiments are needed to optimize culture conditions to support long-term parasite

  19. A Three-Dimensional Analytical Solution for the Study of Air Pollutant Dispersion in a Finite Layer

    NASA Astrophysics Data System (ADS)

    Marie, Ema'a. Ema'a. Jean; Hubert, Ben-Bolie Germain; Patrice, Ele Abiama; Zarma, Ali; Pierre, Owono Ateba

    2015-05-01

    We present a closed-form analytical solution for the advection-diffusion equation, where the planetary boundary layer is divided into subdomains, where in each subdomain averaged values of eddy diffusivity and wind speed are assumed. The solution procedure combines an appropriate auxiliary eigenvalue problem with mathematical induction. A transcendental equation giving the eigenvalues for any numbers of subdomains is also developed. Convergence of the solution is numerically verified. The solution is used to evaluate the model against the Copenhagen experiment and computed results are in agreement with experimental ones.

  20. Bidirectional air-sea exchange and accumulation of POPs (PAHs, PCBs, OCPs and PBDEs) in the nocturnal marine boundary layer

    NASA Astrophysics Data System (ADS)

    Lammel, Gerhard; Meixner, Franz X.; Vrana, Branislav; Efstathiou, Christos I.; Kohoutek, Jiři; Kukučka, Petr; Mulder, Marie D.; Přibylová, Petra; Prokeš, Roman; Rusina, Tatsiana P.; Song, Guo-Zheng; Tsapakis, Manolis

    2016-05-01

    As a consequence of long-range transported pollution, air-sea exchange can become a major source of persistent organic pollutants in remote marine environments. The vertical gradients in the air were quantified for 14 species, i.e. four parent polycyclic aromatic hydrocarbons (PAHs), three polychlorinated biphenyls (PCBs), three organochlorine pesticides (OCPs) and two polybrominated diphenylethers (PBDEs) in the gas-phase at a remote coastal site in the southern Aegean Sea in summer. Most vertical gradients were positive (Δc/Δz > 0), indicating downward (net depositional) flux. Significant upward (net volatilisational) fluxes were found for three PAHs, mostly during daytime, and for two OCPs, mostly during night-time, as well as for one PCB and one PBDE during part of the measurements. While phenanthrene was deposited, fluoranthene (FLT) and pyrene (PYR) seem to undergo flux oscillation, hereby not following a day-night cycle. Box modelling confirms that volatilisation from the sea surface has significantly contributed to the night-time maxima of OCPs. Fluxes were quantified based on eddy covariance. Deposition fluxes ranged from -28.5 to +1.8 µg m-2 day-1 for PAHs and -3.4 to +0.9 µg m-2 day-1 for halogenated compounds. Dry particle deposition of FLT and PYR did not contribute significantly to the vertical flux.

  1. Long-term effects of multiply pulsed dielectric barrier discharges in air on thin water layers over tissue: stationary and random streamers

    NASA Astrophysics Data System (ADS)

    Tian, Wei; Kushner, Mark J.

    2015-12-01

    Tissue covered by thin liquid layers treated by atmospheric pressure plasmas for biomedical applications ultimately requires a reproducible protocol for human healthcare. The desired outcomes of wet tissue treatment by dielectric barrier discharges (DBDs) depend on the plasma dose which determines the integral fluence of radicals, ions, electric fields and UV/VUV photons incident onto the tissue. These fluences are controlled by power, frequency and treatment time. To first order, these parameters determine the energy deposition (J cm-2) onto the tissue. However, energy deposition may not be the only parameter that determines the fluences of reactants to the underlying tissue. In this paper, we report on a computational investigation of multipulse DBDs interacting with wet tissue. The DBDs were simulated for 100 pulses at different repetition rates and liquid thicknesses followed by 10 s or more of afterglow. Two schemes were investigated—stationary and random. In the stationary scheme, the DBD plasma streamer continues to strike at the same location on the liquid layer, whereas in the random scheme the plasma streamer strikes at random locations on the liquid layer. These differences in streamer locations strongly affect the spatial distribution of solvated species such as OHaq and H2O2aq (‘aq’ represents an aqueous species), which have high rates of solvation. The spatial distribution of species such as NOaq, which have low rates of solvation, are less affected by the location of the streamer due to the remediating effects of diffusion in the air. The end result is that fluences to the tissue are sensitive to the spatial location of the streamer due to the ensuing reactions in the liquid between species that have low and high rates of solvation. These reactions can be controlled not only through location of the streamer, but also by repetition rate and thickness of the liquid layer.

  2. Quantitative Interpretation of Air Radon Progeny Fluctuations in Terms of Stability Conditions in the Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Salzano, Roberto; Pasini, Antonello; Casasanta, Giampietro; Cacciani, Marco; Perrino, Cinzia

    2016-03-01

    Determining the mixing height using a tracer can improve the information obtained using traditional techniques. Here we provide an improved box model based on radon progeny measurements, which considers the vertical entrainment of residual layers and the variability in the soil radon exhalation rate. The potential issues in using progeny instead of radon have been solved from both a theoretical and experimental perspective; furthermore, the instrumental efficiency and the counting scheme have been included in the model. The applicability range of the box model has been defined by comparing radon-derived estimates with sodar and lidar data. Three intervals have been analyzed ("near-stable", "transition" and "turbulent"), and different processes have been characterized. We describe a preliminary application case performed in Rome, Italy, while case studies will be required to determine the range limits that can be applied in any circumstances.

  3. Some Observational and Modeling Studies of the Atmospheric Boundary Layer at Mississippi Gulf Coast for Air Pollution Dispersion Assessment

    PubMed Central

    Yerramilli, Anjaneyulu; Challa, Venkata Srinivas; Indracanti, Jayakumar; Dasari, Hariprasad; Baham, Julius; Patrick, Chuck; Young, John; Hughes, Robert; White, Lorren D.; Hardy, Mark G.; Swanier, Shelton

    2008-01-01

    Coastal atmospheric conditions widely vary from those over inland due to the land-sea interface, temperature contrast and the consequent development of local circulations. In this study a field meteorological experiment was conducted to measure vertical structure of boundary layer during the period 25–29 June, 2007 at three locations Seabee base, Harrison and Wiggins sites in the Mississippi coast. A GPS Sonde along with slow ascent helium balloon and automated weather stations equipped with slow and fast response sensors were used in the experiment. GPS sonde were launched at three specific times (0700 LT, 1300 LT and 1800 LT) during the experiment days. The observations indicate shallow boundary layer near the coast which gradually develops inland. The weather research and forecasting (WRF) meso-scale atmospheric model and a Lagrangian particle dispersion model (HYSPLIT) are used to simulate the lower atmospheric flow and dispersion in a range of 100 km from the coast for 28–30 June, 2007. The simulated meteorological parameters were compared with the experimental observations. The meso-scale model results show significant temporal and spatial variations in the meteorological fields as a result of development of sea breeze flow, its coupling with the large scale flow field and the ensuing alteration in the mixing depth across the coast. Simulated ground-level concentrations of SO2 from four elevated point sources located along the coast indicate diurnal variation and impact of the local sea-land breeze on the direction of the plume. Model concentration levels were highest during the stable morning condition and during the sea-breeze time in the afternoon. The highest concentrations were found up to 40 km inland during sea breeze time. The study illustrates the application of field meteorological observations for the validation of WRF which is coupled to HYSPLIT for dispersion assessment in the coastal region. PMID:19151446

  4. Oxygen transport resistance at gas diffusion layer - Air channel interface with film flow of water in a proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Koz, Mustafa; Kandlikar, Satish G.

    2016-01-01

    Water present as films on the gas diffusion layer-air channel interface in a proton exchange membrane fuel cell (PEMFC) alters the oxygen transport resistance, which is expressed through Sherwood number (Sh). The effect of multiple films along the flow length on Sh is investigated through 3D and stationary simulations. The effects of air Péclet number, non-dimensional film width, length, and spacing are studied. Using the simulation results, non-dimensional correlations are developed for local Sh within a mean absolute percentage error of 9%. These correlations can be used for simulating PEMFC performance over temperature and relative humidity ranges of 20-80 °C and 0-100%, respectively. Sh on the film side can be up to 31% lower than that for a dry channel, while a film may reduce the interfacial width by up to 39%. The corresponding increase in transport resistance results in lowering the voltage by 5 and 8 mV respectively at a current density of 1.5 A cm-2. However, their combined effect leads to a voltage loss of 20 mV due to this additional mass transport resistance. It is therefore important to incorporate the additional resistance introduced by the films while modeling fuel cell performance.

  5. Ozone in the boundary layer air over the Arctic Ocean: measurements during the TARA transpolar drift 2006-2008

    NASA Astrophysics Data System (ADS)

    Bottenheim, J. W.; Netcheva, S.; Morin, S.; Nghiem, S. V.

    2009-07-01

    A full year of measurements of surface ozone over the Arctic Ocean far removed from land is presented (81° N-88° N latitude). The data were obtained during the drift of the French schooner TARA between September 2006 and January 2008, while frozen in the Arctic Ocean. The data confirm that long periods of virtually total absence of ozone occur in the spring (mid March to mid June) after Polar sunrise. At other times of the year, ozone concentrations are comparable to other oceanic observations with winter mole fractions of ca. 30-40 nmol mol-1 and summer minima of ca. 20 nmol mol-1. Contrary to earlier observations from ozone sonde data obtained at Arctic coastal observatories, the ambient temperature was well above -20°C during most ODEs (ozone depletion episodes). Backwards trajectory calculations suggest that during these ODEs the air had previously been in contact with the frozen ocean surface for several days and originated largely from the Siberian coast where several large open flaw leads and polynyas developed in the spring of 2007.

  6. Electrical Characteristics, Electrode Sheath and Contamination Layer Behavior of a Meso-Scale Premixed Methane-Air Flame Under AC/DC Electric Fields

    NASA Astrophysics Data System (ADS)

    Chen, Qi; Yan, Limin; Zhang, Hao; Li, Guoxiu

    2016-05-01

    Electrical characteristics of a nozzle-attached meso-scale premixed methane-air flame under low-frequency AC (0-4300 V, 0-500 Hz) and DC (0-3300 V) electric fields were studied. I-V curves were measured under different experimental conditions to estimate the magnitude of the total current 100-102 μA, the electron density 1015-1016 m‑3 and further the power dissipation ≤ 0.7 W in the reaction zone. At the same time, the meso-scale premixed flame conductivity 10‑4-10‑3 Ω‑1·m‑1 as a function of voltage and frequency was experimentally obtained and was believed to represent a useful order-of magnitude estimate. Moreover, the influence of the collision sheath relating to Debye length (31–98 μm) and the contamination layer of an active electrode on measurements was discussed, based on the combination of simulation and theoretical analysis. As a result, the electrode sheath dimension was evaluated to less than 0.5 mm, which indicated a complex effect of the collision sheath on the current measurements. The surface contamination effect of an active electrode was further analyzed using the SEM imaging method, which showed elements immigration during the contamination layer formation process. supported by National Natural Science Foundation of China (No. 51376021), and the Fundamental Research Fund for Major Universities (No. 2013JBM079)

  7. Study of suitability of Fricke-gel-layer dosimeters for in-air measurements to characterise epithermal/thermal neutron beams for NCT.

    PubMed

    Gambarini, G; Artuso, E; Giove, D; Felisi, M; Volpe, L; Barcaglioni, L; Agosteo, S; Garlati, L; Pola, A; Klupak, V; Viererbl, L; Vins, M; Marek, M

    2015-12-01

    The reliability of Fricke gel dosimeters in form of layers for measurements aimed at the characterization of epithermal neutron beams has been studied. By means of dosimeters of different isotopic composition (standard, containing (10)B or prepared with heavy water) placed against the collimator exit, the spatial distribution of gamma and fast neutron doses and of thermal neutron fluence are attained. In order to investigate the accuracy of the results obtained with in-air measurements, suitable MC simulations have been developed and experimental measurements have been performed utilizing Fricke gel dosimeters, thermoluminescence detectors and activation foils. The studies were related to the epithermal beam designed for BNCT irradiations at the research reactor LVR-15 (Řež). The results of calculation and measurements have revealed good consistency of gamma dose and fast neutron 2D distributions obtained with gel dosimeters in form of layers. In contrast, noticeable modification of thermal neutron fluence is caused by the neutron moderation produced by the dosimeter material. Fricke gel dosimeters in thin cylinders, with diameter not greater than 3mm, have proved to give good results for thermal neutron profiling. For greater accuracy of all results, a better knowledge of the dependence of gel dosimeter sensitivity on radiation LET is needed. PMID:26249744

  8. Application of active optical sensors to probe the vertical structure of the urban boundary layer and assess anomalies in air quality model PM 2.5 forecasts

    NASA Astrophysics Data System (ADS)

    Gan, Chuen-Meei; Wu, Yonghua; Madhavan, B. L.; Gross, Barry; Moshary, Fred

    2011-12-01

    In this paper, the simulations of the Weather Research and Forecast (WRF) and Community Multiscale Air Quality (CMAQ) Models applied to the New York City (NYC) area are assessed with the aid of vertical profiling and column integrated remote sensing measurements. First, we find that when turbulent mixing processes are dominant, the WRF-derived planetary boundary layer (PBL) height exhibits a strong linear correlation ( R > 0.85) with lidar-derived PBL height. In these comparisons, we estimate the PBL height from the lidar measurements using a Wavelet Covariance Transform (WCT) approach that is modified to better isolate the convective layer from the residual layer (RL). Furthermore, the WRF-Lidar PBL height comparisons are made using different PBL parameterization schemes, including the Asymmetric Convective Model-version2 (ACM2) and the Modified Blackadar (BLK) scheme (which are both runs using hindcast data), as well as the Mellor-Yamada-Janjic (MYJ) scheme run in forecast mode. Our findings show that the correlations for these runs are high (>0.8), but the hindcast runs exhibit smaller overall dispersion (≈0.1) than the forecast runs. We also apply continuous 24-hour/7-day vertical ceilometer measurements to assess WRF-CMAQ model forecasts of surface PM 2.5 (particulate matter has aerodynamic diameter <2.5 μm). Strong overestimations in the surface PM 2.5 mass that are observed in the summer prior to sunrise are particularly shown to be strongly connected to underestimations of the PBL height and less to enhanced emissions. This interpretation is consistent with observations that TEOM (Tapered Element Oscillating MicroBalance) PM 2.5 measurements are better correlated to path-integrated CMAQ PM 2.5 than the near-surface measurements during these periods.

  9. Application of active optical sensors to probe the vertical structure of the urban boundary layer and assess anomalies in air quality model PM2.5forecasts

    NASA Astrophysics Data System (ADS)

    Gan, Chuen-Meei; Wu, Yonghua; Bomidi, L. M.; Gross, Barry; Moshary, Fred

    2011-11-01

    In this paper, the simulations of the Weather Research and Forecast (WRF) and Community Multiscale Air Quality (CMAQ) Models applied to the New York City (NYC) area are assessed with the aid of vertical profiling and column integrated remote sensing measurements. First, we find that when turbulent mixing processes are dominant, the WRFderived planetary boundary layer (PBL) height exhibits a strong linear correlation (R>0.85) with lidar-derived PBL height. In these comparisons, we estimate the PBL height from the lidar measurements using a Wavelet Covariance Transform (WCT) approach that is modified to better isolate the convective layer from the residual layer (RL). Furthermore, the WRF-Lidar PBL height comparisons are made using different PBL parameterization schemes, including the Asymmetric Convective Model-version2 (ACM2) and the Modified Blackadar (BLK) scheme (which are both runs using hindcast data), as well as the Mellor-Yamada-Janjic (MYJ) scheme run in forecast mode. Our findings show that the correlations for these runs are high (>0.8), but the hindcast runs exhibit smaller overall dispersion (~0.1) than the forecast runs. We also apply continuous 24-hour/7-day vertical ceilometer measurements to assess WRFCMAQ model forecasts of surface PM2.5 (particulate matter has aerodynamic diameter <2.5μm). Strong overestimations in the surface PM2.5 mass that are observed in the summer prior to sunrise are particularly shown to be strongly connected to underestimations of the PBL height and less to enhanced emissions. This interpretation is consistent with observations that TEOM (Tapered Element Oscillating MicroBalance) PM2.5 measurements are better correlated to pathintegrated CMAQ PM2.5 than the near-surface measurements during these periods.

  10. Positive impact of the new 5-layer soil-hydrology scheme on seasonal prediction skill of 2-meter air temperatures over Europe

    NASA Astrophysics Data System (ADS)

    Bunzel, Felix; Müller, Wolfgang; Stacke, Tobias; Hagemann, Stefan; Dobrynin, Mikhail; Baehr, Johanna; Fröhlich, Kristina

    2016-04-01

    Recent studies show that the initialization of soil moisture has the potential to improve the skill of seasonal predictions with coupled climate models. Particularly, soil-moisture memory in the root zone is found to affect the predictability of surface state variables. However, in order to simulate the connection between root-zone soil-moisture and the near-surface atmospheric state realistically, the soil-hydrology scheme implemented in a coupled climate model requires a certain level of complexity. In this study, we first compare the quality of soil-moisture simulation in full-field assimilation experiments performed with the Max Planck Institute Earth System Model (MPI-ESM) in two different setups, one using the old bucket-type soil scheme and one using the new 5-layer soil-hydrology scheme. We find soil moisture to be more realistically simulated when MPI-ESM is used with the new 5-layer soil scheme. In a second step, from each of the two assimilation experiments a set of seasonal hindcast simulations is started. Each hindcast set consists of 10-member ensembles initialized on 1 May and 1 November each year within 1981-2012 with a hindcast length of 6 months each. We find the new 5-layer soil-hydrology scheme to improve the hindcast skill of both summer and winter 2-meter air temperatures over Europe compared to the old bucket-type soil scheme. In order to find possible sources for the improvement, land-atmosphere coupling is analyzed in the two hindcast sets, and a potential link to the atmospheric blocking frequency is investigated.

  11. The study of the effect of the surface wave on turbulent stably-stratified boundary layer air-flow by direct numerical simulation

    NASA Astrophysics Data System (ADS)

    Druzhinin, Oleg; Troitskaya, Yliya; Zilitinkevich, Sergej

    2015-04-01

    Detailed knowledge of the interaction of surface water waves with the wind flow is of primary importance for correct parameterization of turbulent momentum and heat fluxes which define the energy and momentum transfer between the atmosphere and hydrosphere. The objective of the present study is to investigate the properties of the stably stratified turbulent boundary-layer (BL) air-flow over waved water surface by direct numerical simulation (DNS) at a bulk Reynolds number varying from 15000 to 80000 and the surface-wave slope up to ka = 0.2. The DNS results show that the BL-flow remains in the statistically stationary, turbulent regime if the Reynolds number (ReL) based on the Obukhov length scale and friction velocity is sufficiently large (ReL > 100). In this case, mean velocity and temperature vertical profiles are well predicted by log-linear asymptotic solutions following from the Monin-Obukhov similarity theory provided the velocity and temperature roughness parameters, z0U and z0T, are appropriately prescribed. Both z0U and z0T increase for larger surface-wave slope. DNS results also show that turbulent momentum and heat fluxes and turbulent velocity and temperature fluctuations are increased for larger wave slope (ka) whereas the mean velocity and temperature derivatives remain practically the same for different ka. Thus, we conclude that the source of turbulence enhancement in BL-flow are perturbations induced by the surface wave, and not the shear instability of the bulk flow. On the other hand, if stratification is sufficiently strong, and the surface-wave slope is sufficiently small, the BL-flow over waved surface relaminarizes in the bulk of the domain. However, if the surface-wave slope exceeds a threshold value, the velocity and temperature fluctuations remain finite in the vicinity of the critical-layer level, where the surface-wave phase velocity coincides with the mean flow velocity. We call this new stably-stratified BL-flow regime observed in

  12. Study of enhanced red emission from Sm(Sal) 3Phen ternary complexes in Poly Vinyl Alcohol film

    NASA Astrophysics Data System (ADS)

    Kaur, Gagandeep; Dwivedi, Y.; Rai, S. B.

    2010-09-01

    In the present work, dinuclear complexes of salicylic acid (Sal) and 1,10-phenanthroline (Phen) were synthesized with different concentrations of Samarium ion (Sm 3+) in Poly Vinyl Alcohol (PVA) polymer films and their structural and spectroscopic properties were investigated. Judd-Ofelt theory has been employed to estimate the several radiative parameters for SmCl 3 and Sm(Sal) 3Phen complex in PVA polymer film which are in fairly agreement between the experimental and the theoretical values supporting the J-O theory. Photoluminescence properties of the complex have been studied on 355 nm and 400 nm excitations in steady state as well as in time domain. On the basis of the UV-Vis absorption, FT-IR absorption, excitation, emission spectra and decay curves, spectroscopic properties of these films were studied and the photophysics involved was explained in terms of energy transfer and the RE encapsulation effect.

  13. Heavy metal contents of paddy fields of Alcácer do Sal, Portugal.

    PubMed

    Fernandes, J C; Henriques, F S

    1990-01-01

    Recent claims of metal contamination in the lower reaches of the Sado River, in the Alcácer do Sal region, Portugal, a major rice-producing area were investigated by carrying out metal surveys in the area. The elements Fe, Mn, Zn, Cu and Pb were measured in the soil and in rice plant parts--roots, shoots and grain--as well as in some weeds growing in the Sado banks, near the paddy fields. Results showed that the metal contents of paddy soils were similar to background concentrations, with the exception of Zn and Cu, which were above those concentrations and reached their highest levels at Vale de Guizo, the monitored station located furthest upstream in the Sado River. At some sites, plant roots accumulated relatively large amounts of Fe, Mn, Zn and Cu, but the shoot levels of these metals were within the normal range for rice plants. It is possible that varying, but significant, amounts of Fe associated with the roots were in the form of ferric hydroxide plaque covering their surfaces. Copper levels in the shoots of rice were below the normal contents cited for this plant in the literature. Metal levels of river sediments collected near Vale de Guizo seem to corroborate the possibility of some metal contamination in the Sado River, most probably derived from pyrites mining activity in the upper zone of the Sado basin. PMID:2305246

  14. RNAPro•SAL: a device for rapid and standardized collection of saliva RNA and proteins.

    PubMed

    Chiang, Samantha H; Thomas, Gerald A; Liao, Wei; Grogan, Tristan; Buck, Robert L; Fuentes, Laurel; Yakob, Maha; Laughlin, Mary J; Schafer, Chris; Nazmul-Hossain, Abu; Wei, Fang; Elashoff, David; Slowey, Paul D; Wong, David T W

    2015-02-01

    The stabilization and processing of salivary transcriptome and proteome biomarkers is a critical challenge due to the ubiquitous nature of nucleases and proteases as well as the inherent instability of these biomarkers. Furthermore, extension of salivary transcriptome and proteome analysis to point-of-care and remote sites requires the availability of self-administered ambient temperature collection and storage tools. To address these challenges, a self-contained whole saliva collection and extraction system, RNAPro•SAL, has been developed that provides rapid ambient temperature collection along with concurrent processing and stabilization of extracellular RNA (exRNA) and proteins. The system was compared to the University of California, Los Angeles (UCLA) standard clinical collection process (standard operating procedure, SOP). Both systems measured total RNA and protein, and exRNA IL-8, glyceraldehyde 3-phosphate dehydrogenase (GAPDH), β-actin and ribosomal protein S9 (RPS9) by qPCR. Proteome analysis was measured by EIA analysis of interleukin-8 (IL-8), and β-actin, as well as total protein. Over 97% of viable cells were removed by both methods. The system compared favorably to the labor-intensive clinical SOP, which requires low-temperature collection and isolation, yielding samples with similar protein and exRNA recovery and stability. PMID:25652029

  15. SalHUD—A Graphical Interface to Public Health Data in Puerto Rico †

    PubMed Central

    Ortiz-Zuazaga, Humberto G.; Arce-Corretjer, Roberto; Solá-Sloan, Juan M.; Conde, José G.

    2015-01-01

    Purpose: This paper describes SalHUD, a prototype web-based application for visualizing health data from Puerto Rico. Our initial focus was to provide interactive maps displaying years of potential life lost (YPLL). Methods: The public-use mortality file for year 2008 was downloaded from the Puerto Rico Institute of Statistics website. Data was processed with R, Python and EpiInfo to calculate years of potential life lost for the leading causes of death on each of the 78 municipalities in the island. Death records were classified according to ICD-10 codes. YPLL for each municipality was integrated into AtlasPR, a D3 Javascript map library. Additional Javascript, HTML and CSS programing was required to display maps as a web-based interface. Results: YPLL for all municipalities are displayed on a map of Puerto Rico for each of the ten leading causes of death and for all causes combined, so users may dynamically explore the impact of premature mortality. Discussion: This work is the first step in providing the general public in Puerto Rico with user-friendly, interactive, visual access to public health data that is usually published in numerical, text-based media. PMID:26703677

  16. Analysis of the Spread Across Liquid-5 (SAL-5) Experiment Failure to Fill Properly During Flight

    NASA Technical Reports Server (NTRS)

    Allen, Jeffrey Stuart

    2004-01-01

    When a pool of flammable liquid is ignited, the flame spread rate can vary widely depending on the initial fuel temperature, pool geometry, ambient atmospheric conditions, and gravitational level. There is substantial decades-old debate in the scientific literature about the role of gravity in these phenomena. The objective of the research was to measure ignition and flame spread across liquid pools in both normal and microgravity with and without forced airflow, and to obtain detailed thermal and velocity field data for comparison to a predictive numerical model that is concurrently being developed. To that end, an experiment known as Spread Across Liquids 5 (SAL 5) was designed to be conducted in a low-gravity environment on a sounding rocket. Unfortunately, during the sounding rocket flight the fuel tray for the experiment failed to fill properly prior to ignition. The primary cause of the failure to fill properly is the geometry of the fuel tray; that is, the presence of the gaps on the side walls and the sharp edge around the thermocouple through-holes. The contamination resulting from the cleaning process is a strong secondary factor which would have prevented proper, timely filling had the primary cause not been present.

  17. Novel acyloxy derivatives of branched mono- and polyol esters of sal fat: multiviscosity grade lubricant base stocks.

    PubMed

    Kamalakar, Kotte; Sai Manoj, Gorantla N V T; Prasad, Rachapudi B N; Karuna, Mallampalli S L

    2014-12-10

    Sal fat, a nontraditional seed oil, was chemically modified to obtain base stocks with a wide range of specifications that can replace mineral oil base stocks. Sal fatty acids were enriched to 72.6% unsaturation using urea adduct method and reacted with branched mono alcohol, 2-ethylhexanol (2-EtH), and polyols namely neopentyl glycol (NPG) and trimethylolpropane (TMP) to obtain corresponding esters. The esters were hydroxylated and then acylated using propionic, butyric, and hexanoic anhydrides to obtain corresponding acylated derivatives. The acylated TMP esters exhibited very high viscosities (427.35-471.93 cSt at 40 °C) similar to those of BS 150 mineral oil base stock range, ISO VG 460, while the acylated NPG esters (268.81-318.84 cSt at 40 °C) and 2-EtH esters viscosities (20.94-24.44 cSt at 40 °C) exhibited viscosities in the range of ISO VG 320 and 22 respectively with good viscosity indices. Acylated NPG esters were found suitable for high temperature and acylated 2-ethylhexyl esters for low viscosity grade industrial applications. It was observed that the thermo-oxidative stabilities of all acylated products were found better compared to other vegetable oil based base stocks. Overall, all the sal fat based lubricant base stocks are promising candidates with a wide range of properties, which can replace most of the mineral oil base stocks with appropriate formulations. PMID:25416127

  18. Engineering topological superconductors using surface atomic-layer/molecule hybrid materials.

    PubMed

    Uchihashi, Takashi

    2015-08-28

    Surface atomic-layer (SAL) superconductors consisting of epitaxially grown metal adatoms on a clean semiconductor surface have been recently established. Compared to conventional metal thin films, they have two important features: (i) space-inversion symmetry-breaking throughout the system and (ii) high sensitivity to surface adsorption of foreign species. These potentially lead to manifestation of the Rashba effect and a Zeeman field exerted by adsorbed magnetic organic molecules. After introduction of the archetypical SAL superconductor Si(111)-(√7 × √3)-In, we describe how these features are utilized to engineer a topological superconductor with Majorana fermions and discuss its promises and expected challenges. PMID:26234824

  19. Engineering topological superconductors using surface atomic-layer/molecule hybrid materials

    NASA Astrophysics Data System (ADS)

    Uchihashi, Takashi

    2015-08-01

    Surface atomic-layer (SAL) superconductors consisting of epitaxially grown metal adatoms on a clean semiconductor surface have been recently established. Compared to conventional metal thin films, they have two important features: (i) space-inversion symmetry-breaking throughout the system and (ii) high sensitivity to surface adsorption of foreign species. These potentially lead to manifestation of the Rashba effect and a Zeeman field exerted by adsorbed magnetic organic molecules. After introduction of the archetypical SAL superconductor Si(111)-(√7 × √3)-In, we describe how these features are utilized to engineer a topological superconductor with Majorana fermions and discuss its promises and expected challenges.

  20. Geo-diversity and geo-materials in the region of Rabat-Salé-Zemmour-Zaer: Characterization and Rationalization of Utilization

    NASA Astrophysics Data System (ADS)

    Belhaj, Siham; Bahi, Lahcen; Akhssas, Ahmed

    2016-04-01

    The Rabat-Salé-Zemmour-Zaer (RSZZ) is distinguished by a rich geology is varied. Outcrops are found in both the Paleozoic basement, especially along the major wadis in the area and a fairly extensive coverage postpaléozoïque and locally very thick. It offers a wide variety of petrographic facies some of which the construction of geomaterials value (GMC), very solicited by the construction sector and public works (BTP). Among the most important GMC furniture and beds of RSZZ: - The sands. They are a fundamental component for the preparation of mortar and hydraulic concrete. They also enter into the composition of adobe and are used for the foundation of shoes. -The Clays. They are mainly used by ceramists (industrial units manufacturing tiles). The red clay of Triassic age are most represented in the Region in deposits whose thickness can reach several tens of meters. -The Calcarenite. : It is the most used local stone in building the cities of Rabat and Salé, where she is well known as the Stone of Salé. The same stone is used in the manufacture of lime through calcination. Geologically, it is a calcareous sandstone, of Pliocene-Quaternary age that is in the form of a dune system that runs parallel to the Atlantic coast. -The Limestones: These massive limestones and more or less metamorphosed dolomitized Devonian. These limestone outcrop along major wadis of the region (Akrech, Ykem, ...) as layers sometimes quite thick and more or less tectonized. According to localities, these limestones show a wide range of colors (white, gray, black pink) and a wide variety of structures (colorful, beaded, veined, textured) - The quartzites. They correspond to Ordovician bars that appear quite often emerged in relation to other surrounding formations because of their high resistance to erosion. The rock is generally brownish gray and shows a very high hardness related to its siliceous. Local and temporary holdings allow blocks extraction for various public works

  1. Pleiotropic effects of the yeast Sal1 and Aac2 carriers on mitochondrial function via an activity distinct from adenine nucleotide transport

    PubMed Central

    Kucejova, Blanka; Li, Li; Wang, Xiaowen; Giannattasio, Sergio; Chen, Xin Jie

    2009-01-01

    In Saccharomyces cerevisiae, SAL1 encodes a Ca2+-binding mitochondrial carrier. Disruption of SAL1 is synthetically lethal with the loss of a specific function associated with the Aac2 isoform of the ATP/ADP translocase. This novel activity of Aac2 is defined as the V function (for Viability of aac2 sal1 double mutant), which is independent of the ATP/ADP exchange activity required for respiratory growth (the R function). We found that co-inactivation of SAL1 and AAC2 leads to defects in mitochondrial translation and mitochondrial DNA (mtDNA) maintenance. Additionally, sal1Δ exacerbates the respiratory deficiency and mtDNA instability of ggc1Δ, shy1Δ and mtg1Δ mutants, which are known to reduce mitochondrial protein synthesis or protein complex assembly. The V function is complemented by the human Short Ca2+-binding Mitochondrial Carrier (SCaMC) protein, SCaMC-2, a putative ATP-Mg/Pi exchangers on the inner membrane. However, mitochondria lacking both Sal1p and Aac2p are not depleted of adenine nucleotides. The Aac2R252I and Aac2R253I variants mutated at the R252-254 triplet critical for nucleotide transport retain the V function. Likewise, Sal1p remains functionally active when the R479I and R481I mutations were introduced into the structurally equivalent R479-T480-R481 motif. Finally, we found that the naturally occurring V-R+ Aac1 isoform of adenine nucleotide translocase partially gains the V function at the expense of the R function by introducing the mutations P89L and A96V. Thus, our data support the view that the V function is independent of adenine nucleotide transport associated with Sal1p and Aac2p and this evolutionarily conserved activity affects multiple processes in mitochondria. PMID:18431598

  2. Seasonal variation of local atmospheric circulations and boundary layer structure in the Beijing-Tianjin-Hebei region and implications for air quality

    NASA Astrophysics Data System (ADS)

    Miao, Yucong; Hu, Xiao-Ming; Liu, Shuhua; Qian, Tingting; Xue, Ming; Zheng, Yijia; Wang, Shu

    2015-12-01

    The Beijing-Tianjin-Hebei (BTH) region experiences frequent heavy haze pollution in fall and winter. Pollution was often exacerbated by unfavorable atmospheric boundary layer (BL) conditions. The topography in this region impacts the BL processes in complex ways. Such impacts and implications on air quality are not yet clearly understood. The BL processes in all four seasons in BTH are thus investigated in this study using idealized simulations with the WRF-Chem model. Results suggest that seasonal variation of thermal conditions and synoptic patterns significantly modulates BL processes. In fall, with a relatively weak northwesterly synoptic forcing, thermal contrast between the mountains and the plain leads to a prominent mountain-plain breeze circulation (MPC). In the afternoon, the downward branch of the MPC, in addition to northwesterly warm advection, suppresses BL development over the western side of BTH. In the eastern coastal area, a sea-breeze circulation develops late in the morning and intensifies during the afternoon. In summer, southeasterly BL winds allow the see-breeze front to penetrate farther inland (˜150 km from the coast), and the MPC is less prominent. In spring and winter, with strong northwesterly synoptic winds, the sea-breeze circulation is confined in the coastal area, and the MPC is suppressed. The BL height is low in winter due to strong near-surface stability, while BL heights are large in spring due to strong mechanical forcing. The relatively low BL height in fall and winter may have exacerbated the air pollution, thus contributing to the frequent severe haze events in the BTH region.

  3. p-i-n/n-i-p type planar hybrid structure of highly efficient perovskite solar cells towards improved air stability: synthetic strategies and the role of p-type hole transport layer (HTL) and n-type electron transport layer (ETL) metal oxides.

    PubMed

    Mali, Sawanta S; Hong, Chang Kook

    2016-05-19

    There has been fast recent progress in perovskite solar cells (PSCs) towards low cost photovoltaic technology. Organometal mixed halide (MAPbX or FAPbX) perovskites are the most promising light absorbing material sandwiched between the electron transport layer (ETL) and hole transport layer (HTL). These two layers play a critical role in boosting the power conversion efficiency (PCE) and maintaining air stability. However, the device stability is a serious issue in regular as well as p-i-n inverted type perovskite solar cells. This mini-review briefly outlines the state-of-art of p-i-n/n-i-p type planar hybrid perovskite solar cells using MAPbX/FAPbX perovskite absorbing layers. Later, we will focus on recent trends, progress and further opportunities in exploring the air stable hybrid planar structure PSCs. PMID:27161123

  4. p-i-n/n-i-p type planar hybrid structure of highly efficient perovskite solar cells towards improved air stability: synthetic strategies and the role of p-type hole transport layer (HTL) and n-type electron transport layer (ETL) metal oxides

    NASA Astrophysics Data System (ADS)

    Mali, Sawanta S.; Hong, Chang Kook

    2016-05-01

    There has been fast recent progress in perovskite solar cells (PSCs) towards low cost photovoltaic technology. Organometal mixed halide (MAPbX or FAPbX) perovskites are the most promising light absorbing material sandwiched between the electron transport layer (ETL) and hole transport layer (HTL). These two layers play a critical role in boosting the power conversion efficiency (PCE) and maintaining air stability. However, the device stability is a serious issue in regular as well as p-i-n inverted type perovskite solar cells. This mini-review briefly outlines the state-of-art of p-i-n/n-i-p type planar hybrid perovskite solar cells using MAPbX/FAPbX perovskite absorbing layers. Later, we will focus on recent trends, progress and further opportunities in exploring the air stable hybrid planar structure PSCs.

  5. Numerical simulation of VAWT stochastic aerodynamic loads produced by atmospheric turbauence: VAWT-SAL code

    SciTech Connect

    Homicz, G.F.

    1991-09-01

    Blade fatigue life is an important element in determining the economic viability of the Vertical-Axis Wind Turbine (VAWT). A principal source of blade fatigue is thought to be the stochastic (i.e., random) aerodynamic loads created by atmospheric turbulence. This report describes the theoretical background of the VAWT Stochastic Aerodynamic Loads (VAWT-SAL) computer code, whose purpose is to numerically simulate these random loads, given the rotor geometry, operating conditions, and assumed turbulence properties. A Double-Multiple-Stream Tube (DMST) analysis is employed to model the rotor's aerodynamic response. The analysis includes the effects of Reynolds number variations, different airfoil sections and chord lengths along the blade span, and an empirical model for dynamic stall effects. The mean ambient wind is assumed to have a shear profile which is described by either a power law or a logarithmic variation with height above ground. Superimposed on this is a full 3-D field of turbulence: i.e., in addition to random fluctuations in time, the turbulence is allowed to vary randomly in planes perpendicular to the mean wind. The influence of flow retardation on the convection of turbulence through the turbine is also modeled. Calculations are presented for the VAWT 34-m Test Bed currently in operation at Bushland, Texas. Predicted time histories of the loads, as well as their Fourier spectra, are presented and discussed. Particular emphasis is placed on the differences between so-called steady-state'' (mean wind only) predictions, and those produced with turbulence present. Somewhat surprisingly, turbulence is found to be capable of either increasing or decreasing the average output power, depending on the turbine's tip-speed ratio. A heuristic explanation for such behavior is postulated, and a simple formula is derived for predicting the magnitude of this effect without the need for a full stochastic simulation. 41 refs., 32 figs., 1 tab.

  6. Sal-like protein 2 upregulates p16 expression through a proximal promoter element

    PubMed Central

    Wu, Zhenghua; Cheng, Kebin; Shi, Lidan; Li, Zheqi; Negi, Hema; Gao, Guangwei; Kamle, Suchitra; Li, Dawei

    2015-01-01

    Sal-like protein 2 (Sall2), a homeotic transcription factor, is a putative tumor suppressor. We have previously shown that Sall2 activates the transcription of tumor suppressor gene p21 and suppresses tumorigenesis through cell cycle inhibition and induction of apoptosis. To investigate additional Sall2-regulated downstream genes, we analyzed the differences in mRNA expression profiles with and without exogenously expressed Sall2. We identified 1616 Sall2-responsive genes through gene expression arrays. Promoter-reporter assays of p16INK4A and several other tumor-related genes indicated that the Sall2 regulation of these promoters was not significantly different between the two major forms of Sall2 with alternative exon 1 or exon 1A. Additional analysis showed that Sall2-induced p16 promoter activation was Sall2 dose-dependent. Deletion and site-directed mutagenesis of the p16 promoter identified a consensus Sall2 binding site (GGGTGGG) proximal to the p16 transcription start site and was critical for p16 promoter activation. Finally, to confirm the significance of Sall2-activated p16 expression in cell cycle regulation, we co-transfected the SKOV3 cells with a Sall2 expression construct and a p16 minigene and also co-transfected the ES-2 cells with a Sall2 expression construct and the siRNA against p16 for flow cytometry analysis. Our results showed that Sall2 enhanced the p16 minigene blocking of cell cycle progression and p16 knockdown with siRNA abolished most of the Sall2 inhibition of cell cycle progression. These findings indicate that Sall2 targets multiple cell cycle regulators, including p16, through their promoters, adding knowledge to the understanding of Sall2 and p16 gene regulation, and how Sall2 deregulation may promote cancer formation. PMID:25580951

  7. Influence of air exposure duration and a-Si capping layer thickness on the performance of p-BaSi2/n-Si heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Takabe, Ryota; Yachi, Suguru; Du, Weijie; Tsukahara, Daichi; Takeuchi, Hiroki; Toko, Kaoru; Suemasu, Takashi

    2016-08-01

    Fabrication of p-BaSi2(20nm)/n-Si heterojunction solar cells was performed with different a-Si capping layer thicknesses (da-Si) and varying air exposure durations (tair) prior to the formation of a 70-nm-thick indium-tin-oxide electrode. The conversion efficiencies (η) reached approximately 4.7% regardless of tair (varying from 12-150 h) for solar cells with da-Si = 5 nm. In contrast, η increased from 5.3 to 6.6% with increasing tair for those with da-Si = 2 nm, in contrast to our prediction. For this sample, the reverse saturation current density (J0) and diode ideality factor decreased with tair, resulting in the enhancement of η. The effects of the variation of da-Si (0.7, 2, 3, and 5 nm) upon the solar cell performance were examined while keeping tair = 150 h. The η reached a maximum of 9.0% when da-Si was 3 nm, wherein the open-circuit voltage and fill factor also reached a maximum. The series resistance, shunt resistance, and J0 exhibited a tendency to decrease as da-Si increased. These results demonstrate that a moderate oxidation of BaSi2 is a very effective means to enhance the η of BaSi2 solar cells.

  8. In Situ Photocatalytically Heterostructured ZnO-Ag Nanoparticle Composites as Effective Cathode-Modifying Layers for Air-Processed Polymer Solar Cells.

    PubMed

    Yuan, Kai; Chen, Lie; Chen, Yiwang

    2015-08-10

    A heterostructured semiconductor-metal ZnO-Ag nanoparticle (NP) composite was constructed through a straightforward photocatalytic strategy by using UV irradiation of ZnO NPs and an aqueous solution of Ag precursor. The ZnO-Ag NP composites serve as an effective cathode-modifying layer in polymer solar cells (PSCs) with increased short-circuit current density owing to the light-trapping effect, and improved optical and electrical conductivity properties compared with pure ZnO NPs. The Ag NPs, which are photodeposited in situ on ZnO NPs, can act as effective antennas for incident light to maximize light harvesting and minimize radiative decay or nonradiative losses, consequently resulting in the enhanced photogeneration of excitons in PSCs. Systematic photoelectron and -physical investigations confirm that heterostructured ZnO-Ag NPs can significantly improve charge separation, transport, and collection, as well as lower charge recombination at the cathode interface, leading to a 14.0 % improvement in air-processed device power conversion efficiency. In addition, this processable, cost-effective, and scalable approach is compatible with roll-to-roll manufacturing of large-scale PSCs. PMID:26135916

  9. Reorientation of the ‘free OH’ group in the top-most layer of air/water interface of sodium fluoride aqueous solution probed with sum-frequency generation vibrational spectroscopy

    SciTech Connect

    Feng, Ran-Ran; Guo, Yuan; Wang, Hongfei

    2014-09-17

    Many experimental and theoretical studies have established the specific anion, as well as cation effects on the hydrogen-bond structures at the air/water interface of electrolyte solutions. However, the ion effects on the top-most layer of the air/water interface, which is signified by the non-hydrogen-bonded so-called ‘free O-H’ group, has not been discussed or studied. In this report, we present the measurement of changes of the orientational angle of the ‘free O-H’ group at the air/water interface of the sodium fluoride (NaF) solutions at different concentrations using the interface selective sum-frequency generation vibrational spectroscopy (SFG-VS) in the ssp and ppp polarizations. The polarization dependent SFG-VS results show that the average tilt angle of the ‘free O-H’ changes from about 35.3 degrees ± 0.5 degrees to 43.4 degrees ± 2.1degrees as the NaF concentration increase from 0 to 0.94M (nearly saturated). Such tilt angle change is around the axis of the other O-H group of the same water molecule at the top-most layer at the air/water interface that is hydrogen-bonded to the water molecules below the top-most layer. These results provide quantitative molecular details of the ion effects of the NaF salt on the structure of the water molecules at the top-most layer of the air/water interfacial, even though both the Na+ cation and the F- anion are believed to be among the most excluded ions from the air/water interface.

  10. Boundary Layer

    NASA Technical Reports Server (NTRS)

    Loitsianskii. L. G.

    1956-01-01

    The fundamental, practically the most important branch of the modern mechanics of a viscous fluid or a gas, is that branch which concerns itself with the study of the boundary layer. The presence of a boundary layer accounts for the origin of the resistance and lift force, the breakdown of the smooth flow about bodies, and other phenomena that are associated with the motion of a body in a real fluid. The concept of boundary layer was clearly formulated by the founder of aerodynamics, N. E. Joukowsky, in his well-known work "On the Form of Ships" published as early as 1890. In his book "Theoretical Foundations of Air Navigation," Joukowsky gave an account of the most important properties of the boundary layer and pointed out the part played by it in the production of the resistance of bodies to motion. The fundamental differential equations of the motion of a fluid in a laminar boundary layer were given by Prandtl in 1904; the first solutions of these equations date from 1907 to 1910. As regards the turbulent boundary layer, there does not exist even to this day any rigorous formulation of this problem because there is no closed system of equations for the turbulent motion of a fluid. Soviet scientists have done much toward developing a general theory of the boundary layer, and in that branch of the theory which is of greatest practical importance at the present time, namely the study of the boundary layer at large velocities of the body in a compressed gas, the efforts of the scientists of our country have borne fruit in the creation of a new theory which leaves far behind all that has been done previously in this direction. We shall herein enumerate the most important results by Soviet scientists in the development of the theory of the boundary layer.

  11. Air oxidation of hydrazine. 1. Reaction kinetics on natural kaolinites, halloysites, and model substituent layers with varying iron and titanium oxide and O- center contents

    NASA Technical Reports Server (NTRS)

    Coyne, L.; Mariner, R.; Rice, A.

    1991-01-01

    Air oxidation of hydrazine was studied by using a group of kaolinites, halloysites, and substituent oxides as models for the tetrahedral and octahedral sheets. The rate was found to be linear with oxygen. The stoichiometry showed that oxygen was the primary oxidant and that dinitrogen was the only important nitrogen-containing product. The rates on kaolinites were strongly inhibited by water. Those on three-dimensional silica and gibbsite appeared not to be. That on a supposedly layered silica formed from a natural kaolinite by acid leaching showed transitional behavior--slowed relative to that expected from a second-order reaction relative to that on the gibbsite and silica but faster than those on the kaolinites. The most striking result of the reaction was the marked increase in the rate of reaction of a constant amount of hydrazine as the amount of clay was increased. The increase was apparent (in spite of the water inhibition at high conversions) over a 2 order of magnitude variation of the clay weight. The weight dependence was taken to indicate that the role of the clay is very important, that the number of reactive centers is very small, or that they may be deactivated over the course of the reaction. In contrast to the strong dependence on overall amount of clay, the variation of amounts of putative oxidizing centers, such as structural Fe(III), admixed TiO2 or Fe2O3, or O- centers, did not result in alteration of the rate commensurate with the degree of variation of the entity in question. Surface iron does play some role, however, as samples that were pretreated with a reducing agent were less active as catalysts than the parent material. These results were taken to indicate either that the various centers interact to such a degree that they cannot be considered independently or that the reaction might proceed by way of surface complexation, rather than single electron transfers.

  12. Concentrations of Semivolatile Organic Compounds Associated with African Dust Air Masses in Mali, Cape Verde, Trinidad and Tobago, and the U.S. Virgin Islands, 2001-2008

    USGS Publications Warehouse

    Garrison, Virginia H.; Foreman, William T.; Genualdi, Susan A.; Majewski, Michael S.; Mohammed, Azad; Simonich, Staci Massey

    2011-01-01

    Every year, billions of tons of fine particles are eroded from the surface of the Sahara Desert and the Sahel of West Africa, lifted into the atmosphere by convective storms, and transported thousands of kilometers downwind. Most of the dust is carried west to the Americas and the Caribbean in the Saharan Air Layer (SAL). Dust air masses predominately impact northern South America during the Northern Hemisphere winter and the Caribbean and Southeastern United States in summer. Dust concentrations vary considerably temporally and spatially. In a dust source region (Mali), concentrations range from background levels of 575 micrograms per cubic meter (mu/u g per m3) to 13,000 mu/u g per m3 when visibility degrades to a few meters (Gillies and others, 1996). In the Caribbean, concentrations of 200 to 600 mu/u g per m3 in the mid-Atlantic and Barbados (Prospero and others, 1981; Talbot and others, 1986), 3 to 20 mu/u g per m3 in the Caribbean (Prospero and Nees, 1986; Perry and others, 1997); and >100 mu/u g per m3 in the Virgin Islands (this dataset) have been reported during African dust conditions. Mean dust particle size decreases as the SAL traverses from West Africa to the Caribbean and Americas as a result of gravitational settling. Mean particle size reaching the Caribbean is <1 micrometer (mu/u m) (Perry and others, 1997), and even finer particles are carried into Central America, the Southeastern United States, and maritime Canada. Particles less than 2.5 mu/u m diameter (termed PM2.5) can be inhaled deeply into human lungs. A large body of literature has shown that increased PM2.5 concentrations are linked to increased cardiovascular/respiratory morbidity and mortality (for example, Dockery and others, 1993; Penn and others, 2005).

  13. Cathodes for lithium-air battery cells with acid electrolytes

    DOEpatents

    Xing, Yangchuan; Huang, Kan; Li, Yunfeng

    2016-07-19

    In various embodiments, the present disclosure provides a layered metal-air cathode for a metal-air battery. Generally, the layered metal-air cathode comprises an active catalyst layer, a transition layer bonded to the active catalyst layer, and a backing layer bonded to the transition layer such that the transition layer is disposed between the active catalyst layer and the backing layer.

  14. Characterization of sal(A), a Novel Gene Responsible for Lincosamide and Streptogramin A Resistance in Staphylococcus sciuri

    PubMed Central

    Hot, Chloé; Berthet, Nicolas

    2014-01-01

    Natural resistance to lincosamides and streptogramins A (LSA), which is a species characteristic of Bacillus subtilis and Enterococcus faecalis, has never been documented in the Staphylococcus genus. We investigate here the molecular basis of the LSA phenotype exhibited by seven reference strains of Staphylococcus sciuri, including the type strains of the three described subspecies. By whole-genome sequencing of strain ATCC 29059, we identified a candidate gene that encodes an ATP-binding cassette protein similar to the Lsa and VmlR resistance determinants. Isolation and reverse transcription-quantitative PCR (qRT-PCR) expression studies confirmed that Sal(A) can confer a moderate resistance to lincosamides (8 times the MIC of lincomycin) and a high-level resistance to streptogramins A (64 times the MIC of pristinamycin II). The chromosomal location of sal(A) between two housekeeping genes of the staphylococcal core genome supports the gene's ancient origins and thus innate resistance to these antimicrobials within S. sciuri subspecies. PMID:24687494

  15. Luminescence properties of Sm, Tb(Sal)3Phen complex in polyvinyl alcohol: an approach for white-light emission

    NASA Astrophysics Data System (ADS)

    Kaur, Gagandeep; Rai, S. B.

    2011-10-01

    Polyvinyl alcohol polymer films doped with Sm,Tb(Sal)3Phen complexes have been synthesized using solution casting technique. An enhancement in absorption intensity is observed revealing the encapsulation of rare earth ions by salicylic acid (Sal)/1,10 phenanthroline (Phen) complex. Photoluminescence spectra of the co-doped samples were examined by varying the concentration of Tb3+ keeping concentration of Sm3+ ions fixed and vice-versa. It is found that the polymer samples emit a combination of blue, green and orange-red wavelengths tunable to white light when excited with 355 nm radiation. The emission spectra also show a self-quenching effect at higher concentration of Sm3+ ions. An efficient energy transfer was observed from Tb3+ : 5D4 → Sm3+ : 4G9/2. The reason for the enhancement in fluorescence intensities of Sm3+ in the co-doped polymer sample is the intermolecular as well as the intramolecular energy transfer.

  16. /Air Atmospheres

    NASA Astrophysics Data System (ADS)

    Emami, Samar; Sohn, Hong Yong; Kim, Hang Goo

    2014-08-01

    Molten magnesium oxidizes rapidly when exposed to air causing melt loss and handling difficulties. The use of certain additive gases such as SF6, SO2, and CO2 to form a protective MgO layer over a magnesium melt has been proposed. The oxidation behavior of molten magnesium in air containing various concentrations of SF6 was investigated. Measurements of the kinetics of the oxide layer growth at various SF6 concentrations in air and temperatures were made. Experiments were performed using a thermogravimetric analysis unit in the temperature range of 943 K to 1043 K (670 °C to 770 °C). Results showed that a thin, coherent, and protective MgF2 layer was formed under SF6/Air mixtures, with a thickness ranging from 300 nm to 3 μm depending on SF6 concentration, temperature, and exposure time. Rate parameters were calculated and a model for the process was developed. The morphology and composition of the surface films were studied using scanning electron microscope and energy-dispersive spectroscope.

  17. High-resolution distributed temperature sensing: a new tool to study the space-time dynamics of transient cold-air pools in the weak-wind stable boundary layer

    NASA Astrophysics Data System (ADS)

    Thomas, C. K.; Selker, J. S.; Zeeman, M. J.

    2011-12-01

    We present a novel approach to observing the two-dimensional thermal structure of atmospheric near-surface turbulent and non-turbulent flows by measuring air temperatures in a vertical plane at a high resolution (0.25 m, every approximately 2 s) using distributed temperature sensing (DTS). Air temperature observations obtained from a fiber optics array of approximate dimensions 8 by 8 m and sonic anemometer data from two levels were collected for a period of 23 days over a short grass field located in the flat bottom of a wide valley with moderate surface heterogeneity. In addition to evaluating the DTS technique to resolve the rapidly changing gradients and small-scale perturbations associated with turbulence in the atmosphere for convective and stable boundary layers, the objective was to analyze the space-time dynamics of transient cold-air pools in the stable boundary layer. The time response and precision of the fiber temperatures were adequate to resolve individual sub-meter sized turbulent and non-turbulent structures of time scales >= 3 s and enabled calculation of meaningful sensible heat fluxes when combined with vertical wind observations. The small turbulence scales associated with strong vertical shear and low measurement heights pose limitations to the technique. The top of the transient cold-air pool was highly non-stationary. The thermal structure of the near-surface air is generally a superposition of various perturbations of different time and length scales, whereas no preferred scales were identified. Vertical length scales for turbulence in the strongly stratified transient cold-air pool directly derived from the DTS data agreed well with buoyancy length scales parameterized using the vertical velocity variance and the Brunt-Vaisala frequency, while scales for weak stratification disagreed. The high-resolution DTS technique opens a new window into spatially sampling geophysical fluid flows including turbulent energy exchange with a broad

  18. A numerical solution of the Navier-Stokes equations for chemically nonequilibrium, merged stagnation shock layers on spheres and two-dimensional cylinders in air

    NASA Technical Reports Server (NTRS)

    Johnston, K. D.; Hendricks, W. L.

    1978-01-01

    Results of solving the Navier-Stokes equations for chemically nonequilibrium, merged stagnation shock layers on spheres and two-dimensional cylinders are presented. The effects of wall catalysis and slip are also examined. The thin shock layer assumption is not made, and the thick viscous shock is allowed to develop within the computational domain. The results show good comparison with existing data. Due to the more pronounced merging of shock layer and boundary layer for the sphere, the heating rates for spheres become higher than those for cylinders as the altitude is increased.

  19. VERIFICATION OF SURFACE LAYER OZONE FORECASTS IN THE NOAA/EPA AIR QUALITY FORECAST SYSTEM IN DIFFERENT REGIONS UNDER DIFFERENT SYNOPTIC SCENARIOS

    EPA Science Inventory

    An air quality forecast (AQF) system has been established at NOAA/NCEP since 2003 as a collaborative effort of NOAA and EPA. The system is based on NCEP's Eta mesoscale meteorological model and EPA's CMAQ air quality model (Davidson et al, 2004). The vision behind this system is ...

  20. Preparing non-volatile resistive switching memories by tuning the content of Au@air@TiO2-h yolk-shell microspheres in a poly(3-hexylthiophene) layer

    NASA Astrophysics Data System (ADS)

    Wang, Peng; Liu, Quan; Zhang, Chun-Yu; Jiang, Jun; Wang, Li-Hua; Chen, Dong-Yun; Xu, Qing-Feng; Lu, Jian-Mei

    2015-11-01

    Crystalline hybrid microspheres, encapsulating a Au nanocore in the hollow cavity of a hairy semiconductor TiO2 shell (Au@air@TiO2-h microspheres) were prepared using template-assisted synthesis methods. The as-prepared microspheres are dispersed into a poly(3-hexylthiophene) (P3HT) matrix and used as a memory active layer. The electrical rewritable memory effects of Al/[Au@air@TiO2-h + P3HT]/ITO sandwich devices can be effectively and exactly controlled by tuning the microsphere content in the electroactive layer. To clarify the switching mechanism, different components in the device, such as P3HT and the microspheres, have been investigated. And it was determined that the switching mechanism can be attributed to the formation and rupture of oxygen vacancy filaments. These results suggest that the Au@air@TiO2-h microspheres are potentially capable of high density data storage. In addition, this finding could provide important guidelines for the reproducibility of nanocomposite-based memory devices and is helpful to demonstrate the switching mechanism of these devices.Crystalline hybrid microspheres, encapsulating a Au nanocore in the hollow cavity of a hairy semiconductor TiO2 shell (Au@air@TiO2-h microspheres) were prepared using template-assisted synthesis methods. The as-prepared microspheres are dispersed into a poly(3-hexylthiophene) (P3HT) matrix and used as a memory active layer. The electrical rewritable memory effects of Al/[Au@air@TiO2-h + P3HT]/ITO sandwich devices can be effectively and exactly controlled by tuning the microsphere content in the electroactive layer. To clarify the switching mechanism, different components in the device, such as P3HT and the microspheres, have been investigated. And it was determined that the switching mechanism can be attributed to the formation and rupture of oxygen vacancy filaments. These results suggest that the Au@air@TiO2-h microspheres are potentially capable of high density data storage. In addition, this

  1. Attributes of carbapenemase encoding conjugative plasmid pNDM-SAL from an extensively drug-resistant Salmonella enterica Serovar Senftenberg

    PubMed Central

    Sarkar, Anirban; Pazhani, Gururaja P.; Chowdhury, Goutam; Ghosh, Amit; Ramamurthy, Thandavarayan

    2015-01-01

    A carbapenem resistant Salmonella enterica serovar Senftenberg isolate BCH 2406 was isolated from a diarrheal child attending an outpatient unit of B.C. Roy Hospital in Kolkata, India. This isolate was positive for the blaNDM-1 in the PCR assay, which was confirmed by amplicon sequencing. Except for tetracycline, this isolate was resistant to all the tested antimicrobials. The blaNDM-1 was found to be located on a 146.13-kb mega plasmid pNDM-SAL, which could be conjugally transferred into Escherichia coli and other enteric pathogens such as Vibrio cholerae O1 Ogawa and Shigella flexneri 2a. However, the expression of β-lactam resistance is not the same in different bacteria. The whole genome sequence of pNDM-SAL was determined and compared with other pNDM plasmids available in public domain. This plasmid is an IncA/C incompatibility type composed of 155 predicted coding sequences and shares homology with plasmids of E. coli pNDM-1_Dok01, Klebsiella pNDM-KN, and Citrobacter pNDM-CIT. In pNDM-SAL, gene cluster containing blaNDM-1 was located between IS26 and IS4321 elements. Between the IS26 element and the blaNDM-1, a truncated ISAba125 insertion sequence was identified. Downstream of the blaNDM-1, other genes, such as bleMBL, trpF, tat, and an ISCR1 element with class 1 integron containing aac(6′)-Ib were detected. Another β-lactacamase gene, blaCMY -4 was found to be inserted in IS1 element within the type IV conjugative transfer loci of the plasmid. This gene cluster had blc and sugE downstream of the blaCMY -4. From our findings, it appears that the strain S. Senftenberg could have acquired the NDM plasmid from the other members of Enterobacteriaceae. Transfer of NDM plasmids poses a danger in the management of infectious diseases. PMID:26441902

  2. Cumulative ventilation air drying potential as an indication of dry mass content in wastewater sludge in a thin-layer solar drying facility

    NASA Astrophysics Data System (ADS)

    Krawczyk, Piotr

    2013-12-01

    Controlling low-temperature drying facilities which utilise nonprepared air is quite difficult, due to very large variability of ventilation air parameters - both in daily and seasonal cycles. The paper defines the concept of cumulative drying potential of ventilation air and presents experimental evidence that there is a relation between this parameter and condition of the dried matter (sewage sludge). Knowledge on current dry mass content in the dried matter (sewage sludge) provides new possibilities for controlling such systems. Experimental data analysed in the paper was collected in early 2012 during operation of a test solar drying facility in a sewage treatment plant in Błonie near Warsaw, Poland.

  3. The Atmospheric Boundary Layer

    ERIC Educational Resources Information Center

    Tennekes, Hendrik

    1974-01-01

    Discusses some important parameters of the boundary layer and effects of turbulence on the circulation and energy dissipation of the atmosphere. Indicates that boundary-layer research plays an important role in long-term forecasting and the study of air-pollution meteorology. (CC)

  4. Human papillomavirus type 16 E6 inhibits p21{sup WAF1} transcription independently of p53 by inactivating p150{sup Sal2}

    SciTech Connect

    Parroche, Peggy; Touka, Majid; Mansour, Mariam; Bouvard, Veronique; Thepot, Amelie; Accardi, Rosita; Carreira, Christine; Roblot, Guillaume G.; Sylla, Bakary S.; Hasan, Uzma; Tommasino, Massimo

    2011-09-01

    HPV16 E6 deregulates G1/S cell cycle progression through p53 degradation preventing transcription of the CDK inhibitor p21{sup WAF1}. However, additional mechanisms independent of p53 inactivation appear to exist. Here, we report that HPV16 E6 targets the cellular factor p150{sup Sal2}, which positively regulates p21{sup WAF1} transcription. HPV16 E6 associates with p150{sup Sal2}, inducing its functional inhibition by preventing its binding to cis elements on the p21{sup WAF1} promoter. A HPV16 E6 mutant, L110Q, which was unable to bind p150{sup Sal2}, did not affect the ability of the cellular protein to bind p21{sup WAF1} promoter, underlining the linkage between these events. These data describe a novel mechanism by which HPV16 E6 induces cell cycle deregulation with a p53-independent pathway. The viral oncoprotein targets p150{sup Sal2}, a positive transcription regulator of p21{sup WAF1} gene, preventing G1/S arrest and allowing cellular proliferation and efficient viral DNA replication.

  5. Preparing non-volatile resistive switching memories by tuning the content of Au@air@TiO2-h yolk-shell microspheres in a poly(3-hexylthiophene) layer.

    PubMed

    Wang, Peng; Liu, Quan; Zhang, Chun-Yu; Jiang, Jun; Wang, Li-Hua; Chen, Dong-Yun; Xu, Qing-Feng; Lu, Jian-Mei

    2015-12-14

    Crystalline hybrid microspheres, encapsulating a Au nanocore in the hollow cavity of a hairy semiconductor TiO2 shell (Au@air@TiO2-h microspheres) were prepared using template-assisted synthesis methods. The as-prepared microspheres are dispersed into a poly(3-hexylthiophene) (P3HT) matrix and used as a memory active layer. The electrical rewritable memory effects of Al/[Au@air@TiO2-h + P3HT]/ITO sandwich devices can be effectively and exactly controlled by tuning the microsphere content in the electroactive layer. To clarify the switching mechanism, different components in the device, such as P3HT and the microspheres, have been investigated. And it was determined that the switching mechanism can be attributed to the formation and rupture of oxygen vacancy filaments. These results suggest that the Au@air@TiO2-h microspheres are potentially capable of high density data storage. In addition, this finding could provide important guidelines for the reproducibility of nanocomposite-based memory devices and is helpful to demonstrate the switching mechanism of these devices. PMID:26541116

  6. The RON1/FRY1/SAL1 gene is required for leaf morphogenesis and venation patterning in Arabidopsis.

    PubMed

    Robles, Pedro; Fleury, Delphine; Candela, Héctor; Cnops, Gerda; Alonso-Peral, María Magdalena; Anami, Sylvester; Falcone, Andrea; Caldana, Camila; Willmitzer, Lothar; Ponce, María Rosa; Van Lijsebettens, Mieke; Micol, José Luis

    2010-03-01

    To identify genes involved in vascular patterning in Arabidopsis (Arabidopsis thaliana), we screened for abnormal venation patterns in a large collection of leaf shape mutants isolated in our laboratory. The rotunda1-1 (ron1-1) mutant, initially isolated because of its rounded leaves, exhibited an open venation pattern, which resulted from an increased number of free-ending veins. We positionally cloned the RON1 gene and found it to be identical to FRY1/SAL1, which encodes an enzyme with inositol polyphosphate 1-phosphatase and 3' (2'),5'-bisphosphate nucleotidase activities and has not, to our knowledge, previously been related to venation patterning. The ron1-1 mutant and mutants affected in auxin homeostasis share perturbations in venation patterning, lateral root formation, root hair length, shoot branching, and apical dominance. These similarities prompted us to monitor the auxin response using a DR5-GUS auxin-responsive reporter transgene, the expression levels of which were increased in roots and reduced in leaves in the ron1-1 background. To gain insight into the function of RON1/FRY1/SAL1 during vascular development, we generated double mutants for genes involved in vein patterning and found that ron1 synergistically interacts with auxin resistant1 and hemivenata-1 but not with cotyledon vascular pattern1 (cvp1) and cvp2. These results suggest a role for inositol metabolism in the regulation of auxin responses. Microarray analysis of gene expression revealed that several hundred genes are misexpressed in ron1-1, which may explain the pleiotropic phenotype of this mutant. Metabolomic profiling of the ron1-1 mutant revealed changes in the levels of 38 metabolites, including myoinositol and indole-3-acetonitrile, a precursor of auxin. PMID:20044451

  7. High-mobility and air-stable single-layer WS2 field-effect transistors sandwiched between chemical vapor deposition-grown hexagonal BN films

    PubMed Central

    Iqbal, M Waqas; Iqbal, M Zahir; Khan, M Farooq; Shehzad, M Arslan; Seo, Yongho; Park, Jong Hyun; Hwang, Chanyong; Eom, Jonghwa

    2015-01-01

    An emerging electronic material as one of transition metal dichalcogenides (TMDCs), tungsten disulfide (WS2) can be exfoliated as an atomically thin layer and can compensate for the drawback of graphene originating from a gapless band structure. A direct bandgap, which is obtainable in single-layer WS2, is an attractive characteristic for developing optoelectronic devices, as well as field-effect transistors. However, its relatively low mobility and electrical characteristics susceptible to environments remain obstacles for the use of device materials. Here, we demonstrate remarkable improvement in the electrical characteristics of single-layer WS2 field-effect transistor (SL-WS2 FET) using chemical vapor deposition (CVD)-grown hexagonal BN (h-BN). SL-WS2 FET sandwiched between CVD-grown h-BN films shows unprecedented high mobility of 214 cm2/Vs at room temperature. The mobility of a SL-WS2 FET has been found to be 486 cm2/Vs at 5 K. The ON/OFF ratio of output current is ~107 at room temperature. Apart from an ideal substrate for WS2 FET, CVD-grown h-BN film also provides a protection layer against unwanted influence by gas environments. The h-BN/SL-WS2/h-BN sandwich structure offers a way to develop high-quality durable single-layer TMDCs electronic devices. PMID:26030008

  8. High-mobility and air-stable single-layer WS2 field-effect transistors sandwiched between chemical vapor deposition-grown hexagonal BN films.

    PubMed

    Iqbal, M Waqas; Iqbal, M Zahir; Khan, M Farooq; Shehzad, M Arslan; Seo, Yongho; Park, Jong Hyun; Hwang, Chanyong; Eom, Jonghwa

    2015-01-01

    An emerging electronic material as one of transition metal dichalcogenides (TMDCs), tungsten disulfide (WS2) can be exfoliated as an atomically thin layer and can compensate for the drawback of graphene originating from a gapless band structure. A direct bandgap, which is obtainable in single-layer WS2, is an attractive characteristic for developing optoelectronic devices, as well as field-effect transistors. However, its relatively low mobility and electrical characteristics susceptible to environments remain obstacles for the use of device materials. Here, we demonstrate remarkable improvement in the electrical characteristics of single-layer WS2 field-effect transistor (SL-WS2 FET) using chemical vapor deposition (CVD)-grown hexagonal BN (h-BN). SL-WS2 FET sandwiched between CVD-grown h-BN films shows unprecedented high mobility of 214 cm(2)/Vs at room temperature. The mobility of a SL-WS2 FET has been found to be 486 cm(2)/Vs at 5 K. The ON/OFF ratio of output current is ~10(7) at room temperature. Apart from an ideal substrate for WS2 FET, CVD-grown h-BN film also provides a protection layer against unwanted influence by gas environments. The h-BN/SL-WS2/h-BN sandwich structure offers a way to develop high-quality durable single-layer TMDCs electronic devices. PMID:26030008

  9. Lifetime-applied stress response in air of a SiC-based Nicalon-fiber-reinforced composite with a carbon interfacial layer: Effects of temperature (300 to 1150 C)

    SciTech Connect

    Becher, P.F.; Lin, Hua-Tay; More, K.L.

    1998-07-01

    The lifetimes in air as a function of applied flexure stress and temperature (300--1,150 C) are described for a Si-O-C based (Nicalon) fiber plain-weave cloth reinforced SiC-matrix composite ({approximately}7% closed porosity) with an {approximately}0.3 {micro}m thick carbon interfacial layer. The measured lifetimes of both samples with and without an external SiC seal coating were similar and decreased with applied flexural stress (for stresses greater than {approximately}90 MPa) and with temperature. At temperatures of {ge}600 C, the external CVD SiC coating had negligible effect on the lifetimes; however, at 425 C, a detectable improvement in the lifetime was observed with an external SiC coating. When the applied stress was decreased below an apparent threshold stress (e.g., {approximately}90 MPa) for tests conducted at temperatures {le}950 C, no failures were observed for times of {ge}1,000 H. Electron microscopy observations show that the interfacial carbon layer is progressively removed during tests at 425 and 600 C. In these cases, failure is associated with fiber failure and pull-out. At 950 and 1,150 C, the carbon interface layer is eliminated and replaced by a thick silica layer due to the oxidation of the Nicalon fiber and the SiC matrix. This results in embrittling the composite.

  10. Internal Performance of Several Auxiliary Air Inlets Immersed in a Turbulent Boundary Layer at Mach Numbers of 1.3, 1.5, and 2.0

    NASA Technical Reports Server (NTRS)

    Huff, Ronald G; Anderson, Arthur R

    1957-01-01

    Internal performance of normal-shock rectangular, circular, and scoop inlets and of external-compression inlets experimentally obtained with varying immersion in a turbulent boundary layer. Recoveries varied from about 95 percent of theoretical in the free stream to 80 percent with complete immersion, while the corresponding mass flows were usually above 95 percent of theoretical. Turning of the flow through 10 degrees caused losses in pressure recovery of 0.03 to 0.07. External compression did not improve pressure recovery in the boundary layer. Average distortion at critical operation for all inlets was 5 percent.

  11. Multiple layer insulation cover

    DOEpatents

    Farrell, James J.; Donohoe, Anthony J.

    1981-11-03

    A multiple layer insulation cover for preventing heat loss in, for example, a greenhouse, is disclosed. The cover is comprised of spaced layers of thin foil covered fabric separated from each other by air spaces. The spacing is accomplished by the inflation of spaced air bladders which are integrally formed in the cover and to which the layers of the cover are secured. The bladders are inflated after the cover has been deployed in its intended use to separate the layers of the foil material. The sizes of the material layers are selected to compensate for sagging across the width of the cover so that the desired spacing is uniformly maintained when the cover has been deployed. The bladders are deflated as the cover is stored thereby expediting the storage process and reducing the amount of storage space required.

  12. Synthesis, crystal structure and magnetic properties of trinuclear chromium(III) basic carboxylate assembly: [Cr3O(salH)7(H2O)2] (salH2=salicylic acid), a new member of [Cr3O] family

    NASA Astrophysics Data System (ADS)

    Dong, Jinlong; Liu, Bin; Yang, Binsheng

    2016-07-01

    Synthesizing a novel trinuclear chromium(III) basic carboxylate complex could give rise to new materials with interesting properties. Complex [Cr3O(salH)7(H2O)2] is formed in a one-pot, self-assembly reaction when the inert reaction mixture is exposed to dioxygen. The structural property of the complex has been acquired by single-crystal X-ray crystallography and further characterized by elemental analysis (EA), infrared (IR), UV-Visible (UV-Vis), fluorescence spectroscopy and thermo gravimetric and differential thermal analysis (TG-DTA). X-ray structural analysis shows a slightly distorted equilateral of the Cr triangle. The most important feature of the title complex is the unusual framework of the [Cr3O] family due to a terminal Ph(OH)CO2- ion of Cr(2) center, which is unique among the structurally characterized (μ3-oxo)-trichromium(III) complexes. Variable-temperature magnetic susceptibility studies indicate that the total spin value of the ground state is 1/2.

  13. The Simultaneous Electrochemical Detection of Catechol and Hydroquinone with [Cu(Sal-β-Ala)(3,5-DMPz)2]/SWCNTs/GCE

    PubMed Central

    Alshahrani, Lina Abdullah; Li, Xi; Luo, Hui; Yang, Linlin; Wang, Mengmeng; Yan, Songling; Liu, Peng; Yang, Yuqin; Li, Quanhua

    2014-01-01

    A glassy carbon electrode was modified with a copper(II) complex [Cu(Sal-β-Ala) (3,5-DMPz)2] (Sal = salicylaldehyde, β-Ala = β-alanine, 3,5-DMPz = 3,5-dimethylpyrazole) and single-walled carbon nanotubes (SWCNTs). The modified electrode was used to detect catechol (CT) and hydroquinone (HQ) and exhibited good electrocatalytic activities toward the oxidation of CT and HQ. The peak currents were linear with the CT and HQ concentrations over the range of 5–215 μmol·L−1 and 5–370 μmol·L−1 with corresponding detection limits of 3.5 μmol·L−1 and 1.46 μmol·L−1 (S/N = 3) respectively. Moreover, the modified electrode exhibited good sensitivity, stability and reproducibility for the determination of CT and HQ, indicating the promising applications of the modified electrode in real sample analysis. PMID:25429411

  14. Recirculating electric air filter

    DOEpatents

    Bergman, Werner

    1986-01-01

    An electric air filter cartridge has a cylindrical inner high voltage eleode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

  15. Recirculating electric air filter

    DOEpatents

    Bergman, W.

    1985-01-09

    An electric air filter cartridge has a cylindrical inner high voltage electrode, a layer of filter material, and an outer ground electrode formed of a plurality of segments moveably connected together. The outer electrode can be easily opened to remove or insert filter material. Air flows through the two electrodes and the filter material and is exhausted from the center of the inner electrode.

  16. Solving the AI Planning Plus Scheduling Problem Using Model Checking via Automatic Translation from the Abstract Plan Preparation Language (APPL) to the Symbolic Analysis Laboratory (SAL)

    NASA Technical Reports Server (NTRS)

    Butler, Ricky W.; Munoz, Cesar A.; Siminiceanu, Radu I.

    2007-01-01

    This paper describes a translator from a new planning language named the Abstract Plan Preparation Language (APPL) to the Symbolic Analysis Laboratory (SAL) model checker. This translator has been developed in support of the Spacecraft Autonomy for Vehicles and Habitats (SAVH) project sponsored by the Exploration Technology Development Program, which is seeking to mature autonomy technology for the vehicles and operations centers of Project Constellation.

  17. Inorganic-Organic Nanohybrid Materials of Layered Zinc Hydroxide Nitrate with Intercalated Salicylate: Preparation, Characterization and UV-Blocking Properties

    NASA Astrophysics Data System (ADS)

    Liu, Jiexiang; Zhang, Yongqing; Zhang, Xiaoguang

    2016-02-01

    Intercalation of salicylate (Sal) into layered zinc hydroxide nitrate (ZHN) nanohybrid materials was successfully synthesized by the coprecipitation method. The effect of pH, crystallization method, temperature and time of hydrothermal treatment on preparation was investigated in detail and compared. The products were confirmed by X-ray powder diffraction (XRPD), Fourier transform infrared spectroscopy (FTIR), thermogravimetry and differential thermal analysis (TG-DTA), and scanning electron microscope (SEM). The results revealed that ZHN-Sal with pure phase and good crystallinity was obtained at pH = 6.0-6.5, 60∘C and 3h of temperature and time of hydrothermal treatment. The TG-DTA data indicated that the intercalated Sal had a high stability compared to the isolated. And the phases and compositions of the sample calcined at increasing temperatures were also identified by XRPD and FTIR techniques. Furthermore, ZHN-Sal exhibited an improved UV-blocking ability, showing it can be used as a potential alternative matrix for the UV blocker.

  18. Columnar modelling of nucleation burst evolution in the convective boundary layer - first results from a feasibility study Part III: Preliminary results on physicochemical model performance using two "clean air mass" reference scenarios

    NASA Astrophysics Data System (ADS)

    Hellmuth, O.

    2006-09-01

    In Paper I of four papers, a revised columnar high-order model to investigate gas-aerosol-turbulence interactions in the convective boundary layer (CBL) was proposed. In Paper II, the model capability to predict first-, second- and third-order moments of meteorological variables in the CBL was demonstrated using available observational data. In the present Paper III, the high-order modelling concept is extended to sulphur and ammonia chemistry as well as to aerosol dynamics. Based on the previous CBL simulation, a feasibility study is performed using two "clean air mass" scenarios with an emission source at the ground but low aerosol background concentration. Such scenarios synoptically correspond to the advection of fresh post-frontal air in an anthropogenically influenced region. The aim is to evaluate the time-height evolution of ultrafine condensation nuclei (UCNs) and to elucidate the interactions between meteorological and physicochemical variables in a CBL column. The scenarios differ in the treatment of new particle formation (NPF), whereas homogeneous nucleation according to the classical nucleation theory (CNT) is considered. The first scenario considers nucleation of a binary system consisting of water vapour and sulphuric acid (H2SO4) vapour, the second one nucleation of a ternary system additionally involving ammonia (NH3). Here, the two synthetic scenarios are discussed in detail, whereas special attention is payed to the role of turbulence in the formation of the typical UCN burst behaviour, that can often be observed in the surface layer. The intercomparison of the two scenarios reveals large differences in the evolution of the UCN number concentration in the surface layer as well as in the time-height cross-sections of first-order moments and double correlation terms. Although in both cases the occurrence of NPF bursts could be simulated, the burst characteristics and genesis of the bursts are completely different. It is demonstrated, that

  19. Mercury in the marine boundary layer and seawater of the South China Sea: Concentrations, sea/air flux, and implication for land outflow

    NASA Astrophysics Data System (ADS)

    Fu, Xuewu; Feng, Xinbin; Zhang, Gan; Xu, Weihai; Li, Xiangdong; Yao, Hen; Liang, Peng; Li, Jun; Sommar, Jonas; Yin, Runsheng; Liu, Na

    2010-03-01

    Using R/V Shiyan 3 as a sampling platform, measurements of gaseous elemental mercury (GEM), surface seawater total mercury (THg), methyl mercury (MeHg), and dissolved gaseous mercury (DGM) were carried out above and in the South China Sea (SCS). Measurements were collected for 2 weeks (10 to 28 August 2007) during an oceanographic expedition, which circumnavigated the northern SCS from Guangzhou (Canton), Hainan Inland, the Philippines, and back to Guangzhou. GEM concentrations over the northern SCS ranged from 1.04 to 6.75 ng m-3 (mean: 2.62 ng m-3, median: 2.24 ng m-3). The spatial distribution of GEM was characterized by elevated concentrations near the coastal sites adjacent to mainland China and lower concentrations at stations in the open sea. Trajectory analysis revealed that high concentrations of GEM were generally related to air masses from south China and the Indochina peninsula, while lower concentrations of GEM were related to air masses from the open sea area, reflecting great Hg emissions from south China and Indochina peninsula. The mean concentrations of THg, MeHg, and DGM in surface seawater were 1.2 ± 0.3 ng L-1, 0.12 ± 0.05 ng L-1, and 36.5 ± 14.9 pg L-1, respectively. In general, THg and MeHg levels in the northern SCS were higher compared to results reported from most other oceans/seas. Elevated THg levels in the study area were likely attributed to significant Hg delivery from surrounding areas of the SCS primarily via atmospheric deposition and riverine input, whereas other sources like in situ production by various biotic and abiotic processes may be important for MeHg. Average sea/air flux of Hg in the study area was estimated using a gas exchange method (4.5 ± 3.4 ng m-2 h-1). This value was comparable to those from other coastal areas and generally higher than those from open sea environments, which may be attributed to the reemission of Hg previously transported to this area.

  20. Boundary layer dynamics and its parameterization over the central Himalayas: A step towards improved weather and air quality forecasting over complex terrain

    NASA Astrophysics Data System (ADS)

    Solanki, R.

    2015-12-01

    This study aims towards understanding the boundary layer (BL) dynamics and its parameterization, with observations carried out at ARIES, Manora Peak (29.4⁰ N, 79.5⁰ E, 1960 amsl) in the central Himalayas. The site is located over a complex mountainous terrain and the measurements made with Radar Wind Profiler (RWP), ultrasonic anemometer at two levels and a micro pulse LiDAR are being incorporated in this study. Measurement of local BL has been conducted using 1290 MHz radar wind profiler (RWP) as a part of major field campaign, GVAX. The RWP provides 24 hour diurnal cycle of the BL dynamical state over the site. The general criterion of peak in SNR profile being considered as mixed layer (ML) height was found to be inadequate. Therefore, a new approach is implemented according to which the region of SNR above 6 dB was taken as ML. The maxima in monthly-mean ML height is observed to vary from 557 ± 200 m in November (late autumn) to 912 ± 318 m during March (early spring). As a continuation of this study we have attempted to understand the micrometeorology of the site with fast-response measurements (25 Hz) of temperature and wind at two levels above ground using ultrasonic anemometer. These observations are used to derive diurnal variations of surface layer micro-meteorological parameters during fair-weather conditions. Turbulence and gust characteristics of wind over the site have also been parameterized to provide input for dispersion modeling and understand aerosol distribution over the Himalayas. These observations are consolidated with observations of aerosol vertical distribution made with LIDAR for 2 years, identifying the influences on aerosol loadings from IGP via BL evolution and convective mixing. A strong seasonality in aerosol vertical profile within lower 4 km is observed. Finally, these measurements are used to evaluate high resolution (5 km x 5 km) simulations from the Weather Research and Forecasting (WRF) model. Model simulated and measured

  1. Analyzing the Effect of Capillary Force on Vibrational Performance of the Cantilever of an Atomic Force Microscope in Tapping Mode with Double Piezoelectric Layers in an Air Environment.

    PubMed

    Nahavandi, Amir; Korayem, Moharam Habibnejad

    2015-10-01

    The aim of this paper is to determine the effects of forces exerted on the cantilever probe tip of an atomic force microscope (AFM). These forces vary according to the separation distance between the probe tip and the surface of the sample being examined. Hence, at a distance away from the surface (farther than d(on)), these forces have an attractive nature and are of Van der Waals type, and when the probe tip is situated in the range of a₀≤ d(ts) ≤ d(on), the capillary force is added to the Van der Waals force. At a distance of d(ts) ≤ a₀, the Van der Waals and capillary forces remain constant at intermolecular distances, and the contact repulsive force repels the probe tip from the surface of sample. The capillary force emerges due to the contact of thin water films with a thickness of h(c) which have accumulated on the sample and probe. Under environmental conditions a layer of water or hydrocarbon often forms between the probe tip and sample. The capillary meniscus can grow until the rate of evaporation equals the rate of condensation. For each of the above forces, different models are presented. The smoothness or roughness of the surfaces and the geometry of the cantilever tip have a significant effect on the modeling of forces applied on the probe tip. Van der Waals and the repulsive forces are considered to be the same in all the simulations, and only the capillary force is altered in order to evaluate the role of this force in the AFM-based modeling. Therefore, in view of the remarkable advantages of the piezoelectric microcantilever and also the extensive applications of the tapping mode, we investigate vibrational motion of the piezoelectric microcantilever in the tapping mode. The cantilever mentioned is entirely covered by two piezoelectric layers that carry out both the actuation of the probe tip and the measuringof its position. PMID:26324257

  2. High-resolution visibility and air quality forecasting using multi-layer urban canopy model for highly urbanized Hong Kong and the Pearl River Delta

    NASA Astrophysics Data System (ADS)

    Piu NG, Chak; HAO, Song; Fat LAM, Yun

    2015-04-01

    Visibility is a universally critical element which affects the public in many aspects, including economic activities, health of local citizens and safety of marine transportation and aviation. The Interagency Monitoring of Protected Visual Environments (IMPROVE) visibility equation, an empirical equation developed by USEPA, has been modified by various studies to fit into the application upon the Asian continent including Hong Kong and China. Often these studies focused on the improvement of the existing IMPROVE equation by modifying its particulate speciation using local observation data. In this study, we developed an Integrated Forecast System (IFS) to predict the next-day air quality and visibility using Weather Research and Forecasting model with Building Energy Parameterization and Building Energy Model (WRF-BEP+BEM) and Community Multi-scale Air Quality Model (CMAQ). Unlike the other studies, the core of this study is to include detailed urbanization impacts with calibrated "IMPROVE equation for PRD" into the modeling system for Hong Kong's environs. The ultra-high resolution land cover information (~1km x 1km) from Google images, was digitized into the Geographic Information System (GIS) for preparing the model-ready input for IFS. The NCEP FNL (Final) Operation Global Analysis (FNL) and the Global Forecasting System (GFS) datasets were tested for both hind-cast and forecast cases, in order to calibrate the input of urban parameters in the WRF-BEP+BEM model. The evaluation of model performance with sensitivity cases was performed on sea surface temperature (SST), surface temperature (T), wind speed/direction with the major pollutants (i.e., PM10, PM2.5, NOx, SO2 and O3) using local observation and will be presented/discussed in this paper. References: 1. Y. L. Lee, R. Sequeira, Visibility degradation across Hong Kong its components and their relative contribution. Atmospheric Environment 2001, 35, 5861-5872. doi:10.1016/S1352-2310(01)00395-8 2. R. Zhang, Q

  3. Effects of dissolved organic matter (DOM) at environmentally relevant carbon concentrations on atrazine degradation by Chelatobacter heintzii SalB.

    PubMed

    Cheyns, Karlien; Calcoen, Jasper; Martin-Laurent, Fabrice; Bru, David; Smolders, Erik; Springael, Dirk

    2012-09-01

    The dissolved organic matter (DOM) is the term used for organic components of natural origin present in the soil solution and is probably the most available C-source that primes microbial activity in subsoils. Contrasting effects of organic C components on pesticide degradation have been reported; however, most studies have used model organic compounds with compositions and concentrations which differ substantially from those found in the environment. Degradation of atrazine (AT) by Chelatobacter heintzii SalB was monitored in liquid batch assays in the absence or presence of well-defined model C compounds (glucose, gluconate and citrate) as model DOM (mDOM) or complex, less-defined, environmental DOM solutions (eDOM: isolated humic substances, soil and plant residue extracts) at environmentally relevant concentrations. Glucose significantly increased AT degradation rate by more than a factor of 8 at and above 2.5 mg C L( - 1). Optical density measurements showed that this stimulation is related to microbial growth. Gluconate and citrate had no effects unless at non-relevant concentrations (1,000 mg DOC L( - 1)) at which stimulations (gluconate) or inhibitions (citrate) were found. The effects of eDOM added at 10 mg DOC L( - 1) on AT degradation were generally small. The AT degradation time was reduced by factors 1.4-1.9 in the presence of humic acids and eDOM from soils amended with plant residues; however, no effects were found for fulvic acids or eDOM from a soil leachate solution or extracted from unamended peat or forest soil. In conclusion, DOM supplied as both mDOM and eDOM did not inhibit AT degradation at environmentally relevant concentrations, and stimulation can be found for selected DOM samples and this is partly related to its effect on growth. PMID:22159734

  4. Burning Graphene Layer-by-Layer

    PubMed Central

    Ermakov, Victor A.; Alaferdov, Andrei V.; Vaz, Alfredo R.; Perim, Eric; Autreto, Pedro A. S.; Paupitz, Ricardo; Galvao, Douglas S.; Moshkalev, Stanislav A.

    2015-01-01

    Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000 K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in “cold-wall” reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material. PMID:26100466

  5. Burning Graphene Layer-by-Layer.

    PubMed

    Ermakov, Victor A; Alaferdov, Andrei V; Vaz, Alfredo R; Perim, Eric; Autreto, Pedro A S; Paupitz, Ricardo; Galvao, Douglas S; Moshkalev, Stanislav A

    2015-01-01

    Graphene, in single layer or multi-layer forms, holds great promise for future electronics and high-temperature applications. Resistance to oxidation, an important property for high-temperature applications, has not yet been extensively investigated. Controlled thinning of multi-layer graphene (MLG), e.g., by plasma or laser processing is another challenge, since the existing methods produce non-uniform thinning or introduce undesirable defects in the basal plane. We report here that heating to extremely high temperatures (exceeding 2000 K) and controllable layer-by-layer burning (thinning) can be achieved by low-power laser processing of suspended high-quality MLG in air in "cold-wall" reactor configuration. In contrast, localized laser heating of supported samples results in non-uniform graphene burning at much higher rates. Fully atomistic molecular dynamics simulations were also performed to reveal details of oxidation mechanisms leading to uniform layer-by-layer graphene gasification. The extraordinary resistance of MLG to oxidation paves the way to novel high-temperature applications as continuum light source or scaffolding material. PMID:26100466

  6. Surface magnetic properties and magnetoimpedance of Co-rich amorphous and nanocrystalline (Co1-xFex)89 Zr7B4 ribbons with oxide layer formed by long-term exposure to air

    NASA Astrophysics Data System (ADS)

    Eggers, Tatiana; Leary, Alex; McHenry, Michael; Skorvanek, Ivan; Srikanth, Hariharan; Phan, Manh-Huong

    The surface magnetic properties and magnetoimpedance (MI) of amorphous and nanocrystalline (Co1-xFex)89 Zr7B4 melt-spun ribbons with x = 0, 0.025, 0.05 & 0.1 was investigated. A 540°C heat treatment for 1 hour under a 2 T transverse field formed a large volume fraction of nanocrystalline phases in the ribbons, in addition to a well-defined transverse anisotropy indicated by x-ray diffraction and magneto-optical Kerr effect microscopy. After the heat treatment, the ribbon samples were exposed to open air for an extended period of time producing a visible oxide layer on the surfaces. High frequency magnetoimpedance measurements in the driving frequency range of 1-1000 MHz were made to characterize the potential impact of the surface oxide layer on the ac magnetization process. Unique field-dependent behavior of the real and imaginary components of the MI was found in nanocrystalline ribbons with higher Co content (x >= 0.05), showing multiple peaks above 50 MHz driving current.

  7. Boundary Layer Control on Airfoils.

    ERIC Educational Resources Information Center

    Gerhab, George; Eastlake, Charles

    1991-01-01

    A phenomena, boundary layer control (BLC), produced when visualizing the fluidlike flow of air is described. The use of BLC in modifying aerodynamic characteristics of airfoils, race cars, and boats is discussed. (KR)

  8. Air cathode structure manufacture

    DOEpatents

    Momyer, William R.; Littauer, Ernest L.

    1985-01-01

    An improved air cathode structure for use in primary batteries and the like. The cathode structure includes a matrix active layer, a current collector grid on one face of the matrix active layer, and a porous, nonelectrically conductive separator on the opposite face of the matrix active layer, the collector grid and separator being permanently bonded to the matrix active layer. The separator has a preselected porosity providing low IR losses and high resistance to air flow through the matrix active layer to maintain high bubble pressure during operation of the battery. In the illustrated embodiment, the separator was formed of porous polypropylene. A thin hydrophobic film is provided, in the preferred embodiment, on the current collecting metal grid.

  9. Air Pollution

    MedlinePlus

    Air pollution is a mixture of solid particles and gases in the air. Car emissions, chemicals from factories, dust, ... a gas, is a major part of air pollution in cities. When ozone forms air pollution, it's ...

  10. 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 ...

  11. Effectiveness of sal deoiled seed cake as an inducer for protease production from Aeromonas sp. S1 for its application in kitchen wastewater treatment.

    PubMed

    Saini, Vandana; Bhattacharya, Amrik; Gupta, Anshu

    2013-08-01

    The present study is an attempt to demonstrate the feasibility of sal (Shorea robusta) deoiled cake--a forest-based industrial by-product--as a cheaper media supplement for augmented protease production from Aeromonas sp. S1 and application of protease in the treatment of kitchen wastewater. Under optimized conditions, protease production could successfully be enhanced to 5.13-fold (527.5 U mL(-1)) on using sal deoiled seed cake extract (SDOCE), as medium additive, compared to an initial production of 102.7 U mL(-1) in its absence. The culture parameters for optimum production of protease were determined to be incubation time (48 h), pH (7.0), SDOCE concentration (3 % (v/v)), inoculum size (0.3-0.6 % (v/v)), and agitation rate (100 rpm). The enzyme was found to have an optimum pH and temperature of 8.0 and 60 °C, respectively. The protease preparation was tested for treatment of organic-laden kitchen wastewater. After 96 h of wastewater treatment under static condition, enzyme preparation was able to reduce 74 % biological oxygen demand, 37 % total suspended solids, and 41 % oil and grease. The higher and improved level of protease obtained using sal deoiled seed cake-based media hence offers a new approach for value addition to this underutilized biomass through industrial enzyme production. The protease produced using this biomass could also be used as pretreatment tool for remediation of organic-rich food wastewater. PMID:23780343

  12. Open-path TDL-Spectrometry for a Tomographic Reconstruction of 2D H2O-Concentration Fields in the Soil-Air-Boundary-Layer of Permafrost

    NASA Astrophysics Data System (ADS)

    Seidel, Anne; Wagner, Steven; Dreizler, Andreas; Ebert, Volker

    2013-04-01

    The melting of permafrost soils in arctic regions is one of the effects of climate change. It is recognized that climatically relevant gases are emitted during the thawing process, and that they may lead to a positive atmospheric feedback [1]. For a better understanding of these developments, a quantification of the gases emitted from the soil would be required. Extractive sensors with local point-wise gas sampling are currently used for this task, but are hampered due to the complex spatial structure of the soil surface, which complicates the situation due to the essential need for finding a representative gas sampling point. For this situation it would be much preferred if a sensor for detecting 2D-concentration fields of e.g. water vapor, (and in the mid-term also for methane or carbon dioxide) directly in the soil-atmosphere-boundary layer of permafrost soils would be available. However, it also has to be kept in mind that field measurements over long time periods in such a harsh environment require very sturdy instrumentation preferably without the need for sensor calibration. Therefore we are currently developing a new, robust TDLAS (tuneable diode laser absorption spectroscopy)-spectrometer based on cheap reflective foils [2]. The spectrometer is easily transportable, requires hardly any alignment and consists of industrially available, very stable components (e.g. diode lasers and glass fibers). Our measurement technique, open path TDLAS, allows for calibration-free measurements of absolute H2O concentrations. The static instrument for sampling open-path H2O concentrations consists of a joint sending and receiving optics at one side of the measurement path and a reflective element at the other side. The latter is very easy to align, since it is a foil usually applied for traffic purposes that retro-reflects the light to its origin even for large angles of misalignment (up to 60°). With this instrument, we achieved normalized detection limits of up to 0

  13. Large-scale carbonate platform development of Cay Sal Bank, Bahamas, and implications for associated reef geomorphology

    NASA Astrophysics Data System (ADS)

    Purkis, Sam; Kerr, Jeremy; Dempsey, Alexandra; Calhoun, Andrew; Metsamaa, Liisa; Riegl, Bernhard; Kourafalou, Villy; Bruckner, Andrew; Renaud, Philip

    2014-10-01

    The Bahama Archipelago consists of an arcuate chain of carbonate platforms. Average water depths on the platform-tops, such as the Great Bahama Bank (GBB), are typically 10 m or less, with coral reef-rimmed margins, thick sediment accumulations, and the frequent occurrence of islands. There are, however, exceptions. For example, Cay Sal Bank (CSB), a little studied detached Bahamian carbonate platform with depths ranging from 30 to 7 m, is only slightly deeper than the GBB, but devoid of islands, lacks platform-margin coral reefs and holds little sediment on the platform-top; the platform is incipiently drowned. CSB is interesting as it is conspicuously larger (6000 sq. km) than other incipiently drowned platforms in the region, such as Serranilla Bank (1100 sq. km) and the Cat Island platform (1500 sq. km). Field and remote sensing data are assembled to provide insight into the sedimentology and geomorphology of the CSB. The influence of ocean climate, regional hydrodynamics, and Holocene flooding history are investigated to understand why platform-margin coral reef growth on CSB has been unable to keep pace with Holocene sea-level rise. A decade of regional sea-surface temperature data for the Bahamas report CSB to be situated in the same ocean climate regime as GBB. Temperature cannot explain the platform's different morphologies. The Florida Current has been evoked as a possible reason for the immature development of platform-top processes on the CSB, but numeric modeling suggests its influence to be restricted to the deep flanks of the bank. Further, sediment distribution on CSB, including infill patterns of karst depressions, suggest trade winds (easterlies) to drive platform-top hydrodynamics. By assembling a satellite-derived bathymetry map, it can be shown that CSB flooded earlier and at relatively higher rates of Holocene sea-level rise than its neighboring platforms. Flooding history is identified as the most feasible explanation for the atypical

  14. Molecular phylogeny of Caribbean dipsadid (Xenodontinae: Alsophiini) snakes, including identification of the first record from the Cay Sal Bank, The Bahamas.

    PubMed

    Krysko, Kenneth L; Steadman, David W; Nuñez, Leroy P; Lee, David S

    2015-01-01

    We document the first specimen of a dipsadid snake from the Anguilla Cays, Cay Sal Bank, The Bahamas. We analyze 3,426 base pairs (bp) of sequence data derived from five mitochondrial loci and one nuclear locus using Maximum Likelihood (ML) and Bayesian Inference (BI) methods. Our molecular data agree with some aspects of morphology (e.g., scale counts, dentition, and color pattern) supporting identification of this specimen as the Cuban Racer, Cubophis cantherigerus cantherigerus (Bibron 1840), a species previously regarded as endemic to Cuba. This discovery provides another example of the strong Cuban affinities of the terrestrial vertebrate fauna of Bahamian islands. PMID:26624321

  15. Use of pulsed-field agarose gel electrophoresis to size genomes of Campylobacter species and to construct a SalI map of Campylobacter jejuni UA580.

    PubMed

    Chang, N; Taylor, D E

    1990-09-01

    To determine the physical length of the chromosome of Campylobacter jejuni, the genome was subjected to digestion by a series of restriction endonucleases to produce a small number of large restriction fragments. These fragments were then separated by pulsed-field gel electrophoresis with the contour-clamped homogeneous electric field system. The DNA of C. jejuni, with its low G+C content, was found to have no restriction sites for enzymes NotI and SfiI, which cut a high-G+C regions. Most of the restriction enzymes that were used resulted in DNA fragments that were either too numerous or too small for genome size determination, with the exception of the enzymes SalI (5' ... G decreases TCGAG ... 3'), SmaI (5' .... CCC decreases GGG .... 3'), and KpnI (5' ... GGTAC decreases C .... 3'). With SalI, six restriction fragments with average values of 48.5, 80, 110, 220, 280, and 980 kilobases (kb) were obtained when calibrated with both a lambda DNA ladder and yeast Saccharomyces cerevisiae chromosome markers. The sum of these fragments yielded an average genome size of 1.718 megabases (Mb). With SmaI, nine restriction fragments with average values ranging from 39 to 371 kb, which yielded an average genome size of 1.726 Mb were obtained. With KpnI, 11 restriction fragments with sizes ranging from 35 to 387.5 kb, which yielded an average genome size of 1.717 Mb were obtained. A SalI restriction map was derived by partial digestion of the C. jejuni DNA. The genome sizes of C. laridis, C. coli, and C. fetus were also determined with the contour-clamped homogeneous electric field system by SalI, SmaI, and KpnI digestion. Average genome sizes were found to be 1.714 Mb for C. coli, 1.267 Mb for C. fetus subsp. fetus, and 1.451 Mb for C. laridis. PMID:2168376

  16. Sal1p, a calcium-dependent carrier protein that suppresses an essential cellular function associated With the Aac2 isoform of ADP/ATP translocase in Saccharomyces cerevisiae.

    PubMed Central

    Chen, Xin Jie

    2004-01-01

    Adenine nucleotide translocase (Ant) catalyzes ADP/ATP exchange between the cytosol and the mitochondrial matrix. It is also proposed to form or regulate the mitochondrial permeability transition pore, a megachannel of high conductancy on the mitochondrial membranes. Eukaryotic genomes generally contain multiple isoforms of Ant. In this study, it is shown that the Ant isoforms are functionally differentiated in Saccharomyces cerevisiae. Although the three yeast Ant proteins can equally support respiration (the R function), Aac2p and Aac3p, but not Aac1p, have an additional physiological function essential for cell viability (the V function). The loss of V function in aac2 mutants leads to a lethal phenotype under both aerobic and anaerobic conditions. The lethality is suppressed by a strain-polymorphic locus, named SAL1 (for Suppressor of aac2 lethality). SAL1 was identified to encode an evolutionarily conserved protein of the mitochondrial carrier family. Notably, the Sal1 protein was shown to bind calcium through two EF-hand motifs located on its amino terminus. Calcium binding is essential for the suppressor activity. Finally, Sal1p is not required for oxidative phosphorylation and its overexpression does not complement the R(-) phenotype of aac2 mutants. On the basis of these observations, it is proposed that Aac2p and Sal1p may define two parallel pathways that transport a nucleotide substrate in an operational mode distinct from ADP/ATP exchange. PMID:15238515

  17. Clean Air Slots Amid Atmospheric Pollution

    NASA Technical Reports Server (NTRS)

    Hobbs, Peter V.

    2002-01-01

    Layering in the Earth's atmosphere is most commonly seen where parts of the atmosphere resist the incursion of air parcels from above and below - for example, when there is an increase in temperature with height over a particular altitude range. Pollutants tend to accumulate underneath the resulting stable layers. which is why visibility often increases markedly above certain altitudes. Here we describe the occurrence of an opposite effect, in which stable layers generate a layer of remarkably clean air (we refer to these layers as clean-air 'slots') sandwiched between layers of polluted air. We have observed clean-air slots in various locations around the world, but they are particularly well defined and prevalent in southern Africa during the dry season August-September). This is because at this time in this region, stable layers are common and pollution from biomass burning is widespread.

  18. Clean Air Slots Amid Atmospheric Pollution

    NASA Technical Reports Server (NTRS)

    Hobbs, Peter V.

    2002-01-01

    This article investigates the mechanism for those layers in the atmosphere that are free of air borne pollution even though the air above and below them carry pollutants. Atmospheric subsidence is posed as a mechanism for this phenomenon.

  19. Integration of air separation membrane and coalescing filter for use on an inlet air system of an engine

    DOEpatents

    Moncelle, Michael E.

    2003-01-01

    An intake air separation system suitable for combustion air of an internal combustion engine. An air separation device of the system includes a plurality of fibers, each fiber having a tube with a permeation barrier layer on the outer surface thereof and a coalescing layer on the inner surface thereof, to restrict fluid droplets from contacting the permeation barrier layer.

  20. 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 ...

  1. Size distributions of boundary-layer clouds

    SciTech Connect

    Stull, R.; Berg, L.; Modzelewski, H.

    1996-04-01

    Scattered fair-weather clouds are triggered by thermals rising from the surface layer. Not all surface layer air is buoyant enough to rise. Also, each thermal has different humidities and temperatures, resulting in interthermal variability of their lifting condensation levels (LCL). For each air parcel in the surface layer, it`s virtual potential temperature and it`s LCL height can be computed.

  2. The RON1/FRY1/SAL1 Gene Is Required for Leaf Morphogenesis and Venation Patterning in Arabidopsis1[W][OA

    PubMed Central

    Robles, Pedro; Fleury, Delphine; Candela, Héctor; Cnops, Gerda; Alonso-Peral, María Magdalena; Anami, Sylvester; Falcone, Andrea; Caldana, Camila; Willmitzer, Lothar; Ponce, María Rosa; Van Lijsebettens, Mieke; Micol, José Luis

    2010-01-01

    To identify genes involved in vascular patterning in Arabidopsis (Arabidopsis thaliana), we screened for abnormal venation patterns in a large collection of leaf shape mutants isolated in our laboratory. The rotunda1-1 (ron1-1) mutant, initially isolated because of its rounded leaves, exhibited an open venation pattern, which resulted from an increased number of free-ending veins. We positionally cloned the RON1 gene and found it to be identical to FRY1/SAL1, which encodes an enzyme with inositol polyphosphate 1-phosphatase and 3′ (2′),5′-bisphosphate nucleotidase activities and has not, to our knowledge, previously been related to venation patterning. The ron1-1 mutant and mutants affected in auxin homeostasis share perturbations in venation patterning, lateral root formation, root hair length, shoot branching, and apical dominance. These similarities prompted us to monitor the auxin response using a DR5-GUS auxin-responsive reporter transgene, the expression levels of which were increased in roots and reduced in leaves in the ron1-1 background. To gain insight into the function of RON1/FRY1/SAL1 during vascular development, we generated double mutants for genes involved in vein patterning and found that ron1 synergistically interacts with auxin resistant1 and hemivenata-1 but not with cotyledon vascular pattern1 (cvp1) and cvp2. These results suggest a role for inositol metabolism in the regulation of auxin responses. Microarray analysis of gene expression revealed that several hundred genes are misexpressed in ron1-1, which may explain the pleiotropic phenotype of this mutant. Metabolomic profiling of the ron1-1 mutant revealed changes in the levels of 38 metabolites, including myoinositol and indole-3-acetonitrile, a precursor of auxin. PMID:20044451

  3. Spallanzani Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    31 March 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a layered, light-toned mesa among other layered materials exposed in a mound that covers much of the floor of Spallanzani Crater.

    Location near: 58.3oS, 273.9oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  4. Air resources

    SciTech Connect

    1995-10-01

    This section describes the ambient (surrounding) air quality of the TVA region, discusses TVA emission contributions to ambient air quality, and identifies air quality impacts to human health and welfare. Volume 2 Technical Document 2, Environmental Consequences, describes how changes in TVA emissions could affect regional air quality, human health, environmental resources, and materials. The primary region of the affected environment is broadly defined as the state of Tennessee, as well as southern Kentucky, western Virginia, southern West Virginia, western North Carolina, and northern Georgia, Alabama, and Mississippi. This area represents the watershed of the Tennessee River and the 201 counties of the greater TVA service area. Emissions from outside the Tennessee Valley region contribute to air quality in the Valley. Also, TVA emissions are transported outside the Valley and have some impact on air quality beyond the primary study area. Although the study area experiences a number of air quality problems, overall air quality is good.

  5. Air Pollution.

    ERIC Educational Resources Information Center

    Gilpin, Alan

    A summary of one of our most pressing environmental problems, air pollution, is offered in this book by the Director of Air Pollution Control for the Queensland (Australia) State Government. Discussion of the subject is not restricted to Queensland or Australian problems and policies, however, but includes analysis of air pollution the world over.…

  6. Boundary-Layer & health

    NASA Astrophysics Data System (ADS)

    Costigliola, V.

    2010-09-01

    It has long been known that specific atmospheric processes, such as weather and longer-term climatic fluctuations, affect human health. The biometeorological literature refers to this relationship as meteorotropism, defined as a change in an organism that is correlated with a change in atmospheric conditions. Plenty of (patho)physiological functions are affected by those conditions - like the respiratory diseases - and currently it is difficult to put any limits for pathologies developed in reply. Nowadays the importance of atmospheric boundary layer and health is increasingly recognised. A number of epidemiologic studies have reported associations between ambient concentrations of air pollution, specifically particulate pollution, and adverse health effects, even at the relatively low concentrations of pollution found. Since 1995 there have been over twenty-one studies from four continents that have explicitly examined the association between ambient air pollutant mixes and daily mortality. Statistically significant and positive associations have been reported in data from various locations around the world, all with varying air pollutant concentrations, weather conditions, population characteristics and public health policies. Particular role has been given to atmospheric boundary layer processes, the impact of which for specific patient-cohort is, however, not well understood till now. Assessing and monitoring air quality are thus fundamental to improve Europe's welfare. One of current projects run by the "European Medical Association" - PASODOBLE will develop and demonstrate user-driven downstream information services for the regional and local air quality sectors by combining space-based and in-situ data with models in 4 thematic service lines: - Health community support for hospitals, pharmacies, doctors and people at risk - Public information for regions, cities, tourist industry and sporting event organizers - Compliance monitoring support on particulate

  7. Fingering in Confined Elastic Layers

    NASA Astrophysics Data System (ADS)

    Biggins, John; Mahadevan, L.; Wei, Z.; Saintyves, Baudouin; Bouchaud, Elizabeth

    2015-03-01

    Fingering has recently been observed in soft highly elastic layers that are confined between and bonded to two rigid bodies. In one case an injected fluid invades the layer in finger-like protrusions at the layer's perimeter, a solid analogue of Saffman-Taylor viscous fingering. In a second case, separation of the rigid bodies (with maintained adhesion to the layer) leads air to the formation of similar fingers at the layer's perimeter. In both cases the finger formation is reversible: if the fluid is removed or the separation reduced, the fingers vanish. In this talk I will discuss a theoretical model for such elastic fingers that shows that the origin of the fingers is large-strain geometric non-linearity in the elasticity of soft solids. Our simplified elastic model unifies the two types of fingering and accurately estimates the thresholds and wavelengths of the fingers.

  8. XPS study on double glow plasma corrosion-resisting surface alloying layer

    NASA Astrophysics Data System (ADS)

    Ai, Jiahe; Xu, Jiang; He, Fei; Xie, Xishan; Xu, Zhong

    2003-02-01

    Double glow plasma corrosion-resisting surface alloying layer (SAL) formed on low carbon steel 1020 was studied by X-ray photoelectron spectroscopy (XPS) and other means. Results show that the passive film of the surface alloying layer after electrochemical test in 3.5% NaCl solution consists of Cr and Fe oxide such as CrO 3, Cr 2O 3, Fe 2O 3 and FeO and metallic Ni and Mo, and it attributes to the fact that a continuous and compact corrosion-resisting surface alloying layer with rich Cr, Ni and Mo was formed on the surface of steel 1020 so as to increase its corrosion resistance greatly. Therefore, double glow plasma technique will be widely used in corrosion-resisting surface science.

  9. Multiple-layer Radiation Absorber

    NASA Astrophysics Data System (ADS)

    Baker, Robert M. L.; Baker, Bonnie Sue

    A structure is discussed for absorbing incident radiation, either electromagnetic (EM) or sound. Such a surface structure is needed, for example, in a highly sensitive high-frequency gravitational wave or HFGW detector such as the Li-Baker. The multi-layer absorber, which is discussed, is constructed with metamaterial [MM] layer or layers on top. This MM is configured for a specific EM or sound radiation frequency band, which absorbs incident EM or sound radiation without reflection. Below these top MM layers is a substrate of conventional EM-radiation absorbing or acoustical absorbing reflective material, such as an array of pyramidal foam absorbers. Incident radiation is partially absorbed by the MM layer or layers, and then it is more absorbed by the lower absorbing and reflecting substrate. The remaining reflected radiation is even further absorbed by the MM layers on its "way out_ so that essentially all of the incident radiation is absorbed _ a nearly perfect black-body absorber. In a HFGW detector a substrate, such as foam absorbers, may outgas into a high vacuum and reduce the capability of the vacuum-producing equipment, however, the layers above this lowest substrate will seal the absorbing and reflecting substrate from any external vacuum. The layers also serve to seal the absorbing material against air or water flow past the surfaces of aircraft, watercraft or submarines. Other applications for such a multiple-level radiation absorber include stealth aircraft, missiles and submarines.

  10. Layered materials

    NASA Astrophysics Data System (ADS)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  11. Air scrubber for organic solvent removal

    SciTech Connect

    Hawes, P.B.

    1992-02-18

    This patent describes an air scrubber. It comprises: a closed air loop; a cabinet within the air loop; a layer of permeable growth medium near the bottom of the cabinet containing aerobic microorganisms and plants; means for maintaining a portion of the growth medium submerged in water; an air space above the growth medium to accommodate the plants; and means for passing air upwardly through at least a portion of the submerged growth medium. An air scrubber as recited in claim 1 comprising a plurality of water outlets at differing elevations for adjusting the depth of water in the cabinet.

  12. Generation of Fibroblasts Lacking the Sal-like 1 Gene by Using Transcription Activator-like Effector Nuclease-mediated Homologous Recombination

    PubMed Central

    Kim, Se Eun; Kim, Ji Woo; Kim, Yeong Ji; Kwon, Deug-Nam; Kim, Jin-Hoi; Kang, Man-Jong

    2016-01-01

    The Sal-like 1 gene (Sall1) is essential for kidney development, and mutations in this gene result in abnormalities in the kidneys. Mice lacking Sall1 show agenesis or severe dysgenesis of the kidneys. In a recent study, blastocyst complementation was used to develop mice and pigs with exogenic organs. In the present study, transcription activator-like effector nuclease (TALEN)-mediated homologous recombination was used to produce Sall1-knockout porcine fibroblasts for developing knockout pigs. The vector targeting the Sall1 locus included a 5.5-kb 5′ arm, 1.8-kb 3′ arm, and a neomycin resistance gene as a positive selection marker. The knockout vector and TALEN were introduced into porcine fibroblasts by electroporation. Antibiotic selection was performed over 11 days by using 300 μg/mL G418. DNA of cells from G418-resistant colonies was amplified using polymerase chain reaction (PCR) to confirm the presence of fragments corresponding to the 3′ and 5′ arms of Sall1. Further, mono- and bi-allelic knockout cells were isolated and analyzed using PCR–restriction fragment length polymorphism. The results of our study indicated that TALEN-mediated homologous recombination induced bi-allelic knockout of the endogenous gene. PMID:26949958

  13. Positive immunostaining of Sal-like protein 4 is associated with poor patient survival outcome in the large and undifferentiated Korean hepatocellular carcinoma

    PubMed Central

    Jung, Yun Kyung; Jang, Kiseok; Paik, Seung Sam; Kwon, Yong Jin; Kim, Han Jun; Lee, Kyeong Geun; Park, Hwon Kyum

    2016-01-01

    Purpose Previous studies have shown the role of Sal-like protein 4 (SALL4) as a biomarker in hepatocellular carcinoma (HCC), and some studies have shown the relationship between SALL4 and prognosis. Given the debates in study groups differences in terms of etiologic causes between Western and Asian HCC and detection methods, we attempted to verify the features of SALL4 immunoreactivity and its clinical correlation in Korean HCC patients. Methods Immunohistochemical staining of SALL4 of tissue microarrays (TMAs) consisting of 213 surgically resected HCC patients' tissue were scored in a semiquantitative scoring system with immunoreactive score and the results analyzed with clinical outcome, in addition to general demographics and clinical characteristics. Results SALL4 immunoreactivity was expressed in 50 cases. Relevance between SALL4 and α-FP correlated significantly (P = 0.002). Also, the SALL4-positive patients had considerably higher tumor grade (P < 0.001). The survival analysis showed negative correlation with SALL4 immunoreactivity in all HCC patient groups, but SALL4 immunoreactivity in T3 and T4 HCC correlated with poor prognosis. Conclusion Here, we found that positive immunostaining of SALL4 is correlated with poor patient survival outcome in large and undifferentiated Korean HCC. SALL4 expression showed close relationship with clinical outcomes of HCCs in Korean patients. PMID:27433461

  14. Microwave emission from an irregular snow layer

    NASA Technical Reports Server (NTRS)

    Eom, H. J.; Lee, K. K.; Fung, A. K.

    1983-01-01

    Emission from an irregular snow layer is modeled by a layer of Mie scatterers using the radiative transfer method. Comparisons are made with measurements showing snow wetness effects and rough air-snow boundary effects. For convenience of reference, theoretical model behavior is also illustrated.

  15. Microgravity Effects on Plant Boundary Layers

    NASA Technical Reports Server (NTRS)

    Stutte, Gary; Monje, Oscar

    2005-01-01

    The goal of these series of experiment was to determine the effects of microgravity conditions on the developmental boundary layers in roots and leaves and to determine the effects of air flow on boundary layer development. It is hypothesized that microgravity induces larger boundary layers around plant organs because of the absence of buoyancy-driven convection. These larger boundary layers may affect normal metabolic function because they may reduce the fluxes of heat and metabolically active gases (e.g., oxygen, water vapor, and carbon dioxide. These experiments are to test whether there is a change in boundary layer associated with microgravity, quantify the change if it exists, and determine influence of air velocity on boundary layer thickness under different gravity conditions.

  16. Polar Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02153 Polar Layers

    This image of the south polar region shows layered material. It is not known if the layers are formed yearly or if they form over the period of 10s to 100s of years or more.

    Image information: VIS instrument. Latitude -80.3N, Longitude 296.2E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  17. Air Dehydration Membranes for Nonaqueous Lithium-Air Batteries

    SciTech Connect

    Zhang, Jian; Xu, Wu; Li, Xiaohong S; Liu, Wei

    2010-06-11

    In this paper, several types of new membranes were innovated and used as an O2-selective and H2O barrier films attached onto the cathode of non-aqueous Li-air batteries for continuous supplying of dry air into the batteries from ambient air. The membranes were prepared by depositing an O2/H2O selective coating layer on the exterior surface of a newly-invented thin porous Ni substrate sheet at thickness of ~50µm. The coatings tried include hydrophobic silicalite type zeolite and Teflon (PTFE) materials. The melted PTFE-membrane on the porous Ni sheet at 360°C enabled the Li-air batteries with Ketjen black carbon air electrodes to operate in ambient air (with 20% RH) for 21 days with a specific capacity of 1022 mAh/g carbon and a specific energy of 2792 Wh/kg carbon. Its performance is much better than the battery assembled with the same battery material but by use of a commercial, porous PTFE diffusion membranes as the moisture barrier layer on the cathode, which only had a discharge time of five and half days corresponding to a specific capacity of 267 mAh/g carbon and a specific energy of 704Wh/kg carbon. The Li-air battery with the present selective membrane barrier layer even showed better performance in ambient air operation (20% RH) than the reference battery tested in the dry air box (< 1% RH).

  18. Air Pollution.

    ERIC Educational Resources Information Center

    Fox, Donald L.

    1989-01-01

    Materials related to air pollution are reviewed for the period January 1987, to October 1988. The topics are pollution monitoring, air pollution, and environmental chemistry. The organization consists of two major analytical divisions: (1) gaseous methods; and (2) aerosol and particulate methods. (MVL)

  19. Air Pollution.

    EPA Science Inventory

    Air quality is affected by many types of pollutants that are emitted from various sources, including stationary and mobile. These sources release both criteria and hazardous air pollutants, which cause health effects, ecological harm, and material damage. They are generally categ...

  20. The atmospheric boundary layer

    SciTech Connect

    Garratt, J.R.

    1992-01-01

    This book is aimed at researchers in the atmospheric and associated sciences who require a moderately advanced text on the Atmospheric Boundary Layer (ABL) in which the many links between turbulence, air-surface transfer, boundary-layer structure and dynamics, and numerical modeling are discussed and elaborated upon. Chapter 1 serves as an introduction, with Chapters 2 and 3 dealing with the development of mean and turbulence equations, and the many scaling laws and theories that are the cornerstone of any serious ABL treatment. Modelling of the ABL is crucially dependent for its realism on the surface boundary conditions, and Chapters 4 and 5 deal with aerodynamic and energy considerations, with attention to both dry and wet land surfaces and the sea. The structure of the clear-sky, thermally stratified ABL is treated in Chapter 6, including the convective and stable cases over homogeneous land, the marine ABL and the internal boundary layer at the coastline. Chapter 7 then extends the discussion to the cloudy ABL. This is seen as particularly relevant since the extensive stratocumulus regions over the sub-tropical oceans and stratus regions over the Arctic are now identified as key players in the climate system. Finally, Chapters 8 and 9 bring much of the book's material together in a discussion of appropriate ABL and surface parameterization schemes for the general circulation models of the atmosphere that are being used for climate simulation.

  1. Layered Slope

    NASA Technical Reports Server (NTRS)

    2005-01-01

    28 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a frost-covered slope in the south polar region of Mars. The layered nature of the terrain in the south polar region is evident in a series of irregular, somewhat stair-stepped bands that run across the image.

    Location near: 84.3oS, 27.2oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  2. Layers in Melas Chasma

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Click on image for larger annotated version

    This scene of layered deposits is from Melas Chasma, part of the Valles Marineris valley network. The area consists of a series of plateaus and cliffs that form a step-like terrain similar to the Grand Staircase-Escalante region of southwest Utah. The upper-right half of the image covers the highest plateau, and lower cliffs and plateaus step down in elevation toward the lower left of the image. Dunes of dark sand commonly cover the flat plateaus and distinct layers of bedrock are exposed in the cliffs. The orientations of these layers may help scientists to understand how the layers formed and the kind of environment that the layers formed in. Black rectangles on the left side of the image are areas where the image data was lost during transmission from Mars Reconnaissance Orbiter to Earth. This subscene [above] shows a series of boulder tracks on the left side of the image. The boulders fell from the cliffs above and left behind a series of small depressions. Each depression was made as the boulder bounced and rolled along the surface. In many cases, the tracks can be followed to the specific boulder that made them. Also visible in this subscene are cross-sections through the layered bedrock. This bedrock likely formed through settling of sand-sized particles out of the air or out of a body of water that has since drained away. These layers are 'cross-bedded', which means that subsequent layers are not parallel to each other but are instead oriented at an angle to other layers. The fact that these layers are cross-bedded indicates that the sand-sized particles were moved horizontally along the surface as they settled, just like sand dunes or ripples at the bottom of a stream. The size and shape of these cross-beds may help scientists to determine if the layers formed underwater or on land.

    Image PSP_001377_1685 was taken by the High Resolution Imaging

  3. Relative sea-level change, climate, and sequence boundaries: insights from the Kimmeridgian to Berriasian platform carbonates of Mount Salève (E France)

    NASA Astrophysics Data System (ADS)

    Bover-Arnal, Telm; Strasser, André

    2013-03-01

    The present study analyses the stratal architecture of the Late Jurassic (Kimmeridgian) to Early Cretaceous (Berriasian) sedimentary succession of Mount Salève (E France), and four Berriasian stratigraphic intervals containing four sequence-boundary zones reflecting lowering trends of the relative sea-level evolution. Massive Kimmeridgian limestones characterized by the presence of colonial corals appear to be stacked in an aggrading pattern. These non-bedded thick deposits, which are interpreted to have formed in balance between relative sea-level rise and carbonate accumulation, suggest a keep-up transgressive system. Above, well-bedded Tithonian-to-Berriasian peritidal carbonates reflect a general loss of accommodation. These strata are interpreted as a highstand normal-regressive unit. During the early phase of this major normal regression, the vertical repetition of upper intertidal/lower supratidal lithofacies indicates an aggrading depositional system. This is in agreement with an early stage of a highstand phase of relative sea level. The Berriasian sequence-boundary zones investigated (up to 4 m thick) developed under different climatic conditions and correspond to higher-frequency, forced- and normal-regressive stages of relative sea-level changes. According to the classical sequence-stratigraphic principles, these sequence-boundary zones comprise more than one candidate surface for a sequence boundary. Three sequence-boundary zones studied in Early Berriasian rocks lack coarse siliciclastic grains, contain a calcrete crust, as well as marly levels with higher abundances of illite with respect to kaolinite, and exhibit fossilized algal-microbial laminites with desiccation polygons. These sedimentary features are consistent with more arid conditions. A sequence-boundary zone interpreted for the Late Berriasian corresponds to a coal horizon. The strata above and below this coal contain abundant quartz and marly intervals with a higher kaolinite content

  4. Uranium and lanthanides in surficial sediments of Laguna Ojo de Liebre and evaporation ponds of Exportadora de Sal, Guerrero Negro, México.

    NASA Astrophysics Data System (ADS)

    Grajeda-Muñoz, M. M.; Choumiline, E.; Zaposhnikov, D.

    2007-05-01

    To assess uranium and lanthanides behavior in hypersaline environments, surficial sediment samples were taken from Laguna Ojo de Liebre as well as from the evaporation ponds of Exportadora de Sal (the largest natural salt producing facility in the continent). A total of 63 surficial sediment samples from the laguna and 30 samples from the ponds were analyzed by inductive coupled plasma-mass spectrometry for uranium (sediments, deposits and solution) and instrumental neutron activation analysis for REEs in sediments and deposits. Results show that the behavior is all but similar between light and heavy REEs with the exception of Eu which shows a very different pattern of surficial distribution in Laguna Ojo de Liebre with a maximum concentrations in the sediments near the head of the lagoon. Data normalized with North American Shale Composite (NASC) show 3 distinct signature patterns on the surficial sediments, all of them enriched regarding the values of NASC. As for U total content in sediments and solid deposits it shows a higher concentration towards the head of the lagoon (3 mg/kg), from where the water is pumped to the sequence of evaporation ponds, with the lowest values being close to 1 mg/kg near the mouth of the lagoon. The interesting phenomenon begins in the evaporation ponds, where uranium is almost constant in sediments and deposits (0.15-1.5 mg/kg) but behaves conservately in the brine solution, increasing proportionally with salt content (U, 5-20 mg/kg; salt content, 40-250 g/kg). Non lithogenic U was calculated with Sc as reference. Most of the measured U was non lithogenic in the sediments of the lagoon and ponds. The distribution coefficient k= U(non-lith)/U(dis) shows a maximum value at ponds I and II (salt content 40-80 g/kg) decreasing with increasing salinity.

  5. SALS-linked WT-SOD1 adopts a highly similar helical conformation as FALS-causing L126Z-SOD1 in a membrane environment.

    PubMed

    Lim, Liangzhong; Song, Jianxing

    2016-09-01

    So far >180 mutations have been identified within the 153-residue human SOD1 to cause familial amyotrophic lateral sclerosis (FALS), while wild-type (WT) SOD1 was intriguingly implicated in sporadic ALS (SALS). SOD1 mutations lead to ALS by a dominant gain of cytotoxicity but its mechanism still remains elusive. Previously functional studies have revealed that SOD1 mutants became unexpectedly associated with organelle membranes. Indeed we decoded that the ALS-causing truncation mutant L126Z-SOD1 with an elevated toxicity completely loses the ability to fold into the native β-barrel structure but acquire a novel capacity to interact with membranes by forming helices over hydrophobic/amphiphilic segments. Very recently, the abnormal insertion of SOD1 mutants into ER membrane has been functionally characterized to trigger ER stress, an initial event of a cascade of cell-specific damages in ALS pathogenesis. Here we attempted to understand the mechanism for gain of cytotoxicity of the WT SOD1. We obtained atomic-resolution evidence that the nascent WT SOD1 without metalation and disulfide bridge is also highly disordered as L126Z. Most importantly, it owns the same capacity in interacting with membranes by forming very similar helices over the first 125 residues identical to L126Z-SOD1, plus an additional hydrophobic helix over Leu144-Ala152. Our study thus implies that the WT and mutant SOD1 indeed converge on a common mechanism for gain of cytotoxicity by abnormally interacting with membranes. Moreover, any genetic/environmental factors which can delay or impair its maturation might act to transform SOD1 into cytotoxic forms with the acquired capacity to abnormally interact with membranes. PMID:27378311

  6. An Experiment to Study Sporadic Sodium Layers in the Earth's Mesosphere and Lower Thermosphere

    NASA Technical Reports Server (NTRS)

    Swenson, Charles M.

    2002-01-01

    The Utah State University / Space Dynamics Lab was funded under a NASA Grant. This investigation has been part of Rockwell Universities Sudden Atom Layer Investigation (SAL). USU/SDL provided an electron density measurement instrument, the plasma frequency probe, which was launched on the vehicle 21.117 from Puerto-Rico in February of 1998. The instrument successfully measured electron density as designed and measurement techniques included in this version of the Plasma Frequency probe provided valuable insight into the electron density structures associated with sudden sodium layers in a collisional plasma. Electron density data was furnished to Rockwell University but no science meetings were held by Rockwell Data from the instrument was presented to the scientific community at the URSI General Session in 1999. A paper is in preparation for publication in Geophysical Research Letters. The following document provides a summary of the experiment and data obtained as a final report on this grant.

  7. Air Pollution

    MedlinePlus

    ... tobacco smoke. How is air pollution linked to climate change? While climate change is a global process, it ... ozone levels are also a concern. Impacts of Climate Change on Human Health in the United States: A ...

  8. Air Apparent.

    ERIC Educational Resources Information Center

    Harbster, David A.

    1988-01-01

    Explains the principle upon which a barometer operates. Describes how to construct two barometric devices for use in the classroom that show air's changing pressure. Cites some conditions for predicting weather. (RT)

  9. Double Layers in Astrophysics

    NASA Technical Reports Server (NTRS)

    Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)

    1987-01-01

    Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

  10. Degradation characteristics of air cathode in zinc air fuel cells

    NASA Astrophysics Data System (ADS)

    Ma, Ze; Pei, Pucheng; Wang, Keliang; Wang, Xizhong; Xu, Huachi; Liu, Yongfeng; peng, Guanlin

    2015-01-01

    The zinc air fuel cell (ZAFC) is a promising candidate for electrical energy storage and electric vehicle propulsion. However, its limited durability has become a major obstacle for its successful commercialization. In this study, 2-cell stacks, 25 cm² cells and three-electrode half-cells are constructed to experimentally investigate the degradation characteristics of the air cathode. The results of electrochemical tests reveal that the peak power density for the 25 cm2 cell with a new air cathode is 454 mW cm-2, which is twice as the value of the used air cathode. The electrochemical impedance analysis shows that both the charge transfer resistance and the mass transfer resistance of the used air cathodes have increased, suggesting that the catalyst surface area and gas diffusion coefficient have decreased significantly. Additionally, the microstructure and morphology of the catalytic layer (CL) and gas diffusion layer (GDL) are characterized by scanning electron microscopes (SEM). SEM results confirm that the micropores in CL and GDL of the used air cathode are seriously clogged, and many catalyst particles are lost. Therefore, the performance degradation is mainly due to the clogging of micropores and loss of catalyst particles. Furthermore, hypotheses of degradation mechanism and mitigation strategies for GDL and CL are discussed briefly.

  11. Ultrasonic classification of thin layers within multi-layered materials

    NASA Astrophysics Data System (ADS)

    Hägglund, F.; Carlson, J. E.; Andersson, T.

    2010-01-01

    Methods for non-destructive inspection of layered materials are becoming more and more popular as a way of assuring product integrity and quality. In this paper, we present a model-based technique using ultrasonic measurements for classification of thin bonding layers within three-layered materials. This could be, for example, an adhesive bond between two thin plates, where the integrity of the bonding layer needs to be evaluated. The method is based on a model of the wave propagation of pulse-echo ultrasound that first reduces the measured data to a few parameters for each measured point. The model parameters are then fed into a statistical classifier that assigns the bonding layer to one of a set of predefined classes. In this paper, two glass plates are bonded together with construction silicone, and the classifiers are trained to determine if the bonding layer is intact or if it contains regions of air or water. Two different classification methods are evaluated: nominal logistic regression and discriminant analysis. The former is slightly more computationally demanding but, as the results show, it performs better when the model parameters cannot be assumed to belong to a multivariate Gaussian distribution. The performance of the classifiers is evaluated using both simulations and real measurements.

  12. Layered Fan

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03692 Layered Fan

    This beautiful fan deposit is located at the end of a mega-gully that empties into the southern trough of Coprates Chasma.

    Image information: VIS instrument. Latitude -14.9N, Longitude 299.8E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  13. 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).

  14. LBSapSal-vaccinated dogs exhibit increased circulating T-lymphocyte subsets (CD4+ and CD8+) as well as a reduction of parasitism after challenge with Leishmania infantum plus salivary gland of Lutzomyia longipalpis

    PubMed Central

    2014-01-01

    Background The development of a protective vaccine against canine visceral leishmaniasis (CVL) is an alternative approach for interrupting the domestic cycle of Leishmania infantum. Given the importance of sand fly salivary proteins as potent immunogens obligatorily co-deposited during transmission of Leishmania parasites, their inclusion in an anti-Leishmania vaccine has been investigated in the last few decades. In this context, we previously immunized dogs with a vaccine composed of L. braziliensis antigens plus saponin as the adjuvant and sand fly salivary gland extract (LBSapSal vaccine). This vaccine elicited an increase in both anti-saliva and anti-Leishmania IgG isotypes, higher counts of specific circulating CD8+ T cells, and high NO production. Methods We investigated the immunogenicity and protective effect of LBSapSal vaccination after intradermal challenge with 1 × 107 late-log-phase L. infantum promastigotes in the presence of sand fly saliva of Lutzomyia longipalpis. The dogs were followed for up to 885 days after challenge. Results The LBSapSal vaccine presents extensive antigenic diversity with persistent humoral and cellular immune responses, indicating resistance against CVL is triggered by high levels of total IgG and its subtypes (IgG1 and IgG2); expansion of circulating CD5+, CD4+, and CD8+ T lymphocytes and is Leishmania-specific; and reduction of splenic parasite load. Conclusions These results encourage further study of vaccine strategies addressing Leishmania antigens in combination with proteins present in the saliva of the vector. PMID:24507702

  15. Characterization of salA, syrF, and syrG Genes and Attendant Regulatory Networks Involved in Plant Pathogenesis by Pseudomonas syringae pv. syringae B728a

    PubMed Central

    Vaughn, Vanessa L.; Gross, Dennis C.

    2016-01-01

    Pseudomonas syringae pv. syringae B728a, causal agent of brown spot on bean, is an economically important plant pathogen that utilizes extracellular signaling to initiate a lifestyle change from an epiphyte to a pathogen. LuxR regulatory proteins play an important role in the transcriptional regulation of a variety of biological processes involving two-component signaling, quorum sensing, and secondary metabolism. Analysis of the B728a genome identified 24 LuxR-like proteins, three of which are encoded by salA, syrF, and syrG located adjacent to the syringomycin gene cluster. The LuxR-like proteins encoded by these three genes exhibit a domain architecture that places them in a subfamily of LuxR-like proteins associated with regulation of secondary metabolism in B728a. Deletion mutants of salA, syrF, and syrG failed to produce syringomycin and displayed reduction of virulence on bean. The transcriptional start sites of salA, syrG, and syrF were located 63, 235, and 498 bp upstream of the start codons, respectively, using primer extension analysis. The predicted -10/-35 promoter regions of syrF and syrG were confirmed using site-directed mutagenesis and GFP reporters that showed conserved promoter sequences around the -35 promoter region. Overexpression analysis and GFP reporters identified SyrG as an upstream transcriptional activator of syrF, where both SyrG and SyrF activate promoters of syringomycin biosynthesis genes. This study shows that syrG and syrF encode important transcriptional regulators of syringomycin biosynthesis genes. PMID:26954255

  16. Sea-ice melt CO2-carbonate chemistry in the western Arctic Ocean: meltwater contributions to air-sea CO2 gas exchange, mixed-layer properties and rates of net community production under sea ice

    NASA Astrophysics Data System (ADS)

    Bates, N. R.; Garley, R.; Frey, K. E.; Shake, K. L.; Mathis, J. T.

    2014-12-01

    The carbon dioxide (CO2)-carbonate chemistry of sea-ice melt and co-located, contemporaneous seawater has rarely been studied in sea-ice-covered oceans. Here, we describe the CO2-carbonate chemistry of sea-ice melt (both above sea-ice as "melt ponds" and below sea-ice as "interface waters") and mixed-layer properties in the western Arctic Ocean in the early summer of 2010 and 2011. At 19 stations, the salinity (∼0.5 to <6.5), dissolved inorganic carbon (DIC; ∼20 to <550 μmol kg-1) and total alkalinity (TA; ∼30 to <500 μmol kg-1) of above-ice melt pond water was low compared to the co-located underlying mixed layer. The partial pressure of CO2 (pCO2) in these melt ponds was highly variable (∼<10 to >1500 μatm) with the majority of melt ponds acting as potentially strong sources of CO2 to the atmosphere. The pH of melt pond waters was also highly variable ranging from mildly acidic (6.1 to 7) to slightly more alkaline than underlying seawater (>8.2 to 10.8). All of the observed melt ponds had very low (<0.1) saturation states (Ω) for calcium carbonate (CaCO3) minerals such as aragonite (Ωaragonite). Our data suggest that sea-ice generated alkaline or acidic type melt pond water. This melt water chemistry dictates whether the ponds are sources of CO2 to the atmosphere or CO2 sinks. Below-ice interface water CO2-carbonate chemistry data also indicated substantial generation of alkalinity, presumably owing to dissolution of CaCO3 in sea-ice. The interface waters generally had lower pCO2 and higher pH/Ωaragonite than the co-located mixed layer beneath. Sea-ice melt thus contributed to the suppression of mixed-layer pCO2, thereby enhancing the surface ocean's capacity to uptake CO2 from the atmosphere. Our observations contribute to growing evidence that sea-ice CO2-carbonate chemistry is highly variable and its contribution to the complex factors that influence the balance of CO2 sinks and sources (and thereby ocean acidification) is difficult to

  17. Air Pollution.

    ERIC Educational Resources Information Center

    Scorer, Richard S.

    The purpose of this book is to describe the basic mechanisms whereby pollution is transported and diffused in the atmosphere. It is designed to give practitioners an understanding of basic mechanics and physics so they may have a correct basis on which to formulate their decisions related to practical air pollution control problems. Since many…

  18. Air Pollution

    PubMed Central

    Clifton, Marjorie

    1964-01-01

    Dr Marjorie Clifton describes the classification of gaseous and nongaseous constituents of air pollution and then outlines the methods of measuring these. The National Survey embraced 150 towns of all sizes throughout England and Wales and provided data on smoke and sulphur dioxide in relation to climate, topography, industrialization, population density, fuel utilization and urban development. Dr W C Turner discusses the relationship between air pollution and mortality from respiratory conditions, and particularly the incidence of chronic bronchitis. He postulates a theory that such respiratory conditions arise as an allergy to the spores of certain moulds, spore formation being encouraged by the air humidity in Greatv Britain and overcrowded and damp living conditions. He describes the results of a twenty-week study undertaken in 1962-3, showing associations between respiratory disease and levels of air pollution. Dr Stuart Carne undertook a survey in general practice to plot the patterns of respiratory illness in London during the winter of 1962-3. There were two peaks of respiratory illnesses coinciding with the fog at the beginning of December and the freeze-up from the end of December until the beginning of March. PMID:14178955

  19. Air Trafficco

    ERIC Educational Resources Information Center

    Kasunic, Kevin

    1970-01-01

    The work of the 14,000 air traffic controllers can be both challenging and nerve-racking. Concentration, steady nerves, and a clear voice are required to remember the routing and identification of the maze of aircraft and to instruct each of them accurately. Controllers must have a high school diploma and three years work experience or a college…

  20. Sea-ice melt CO2-carbonate chemistry in the western Arctic Ocean: meltwater contributions to air-sea CO2 gas exchange, mixed layer properties and rates of net community production under sea ice

    NASA Astrophysics Data System (ADS)

    Bates, N. R.; Garley, R.; Frey, K. E.; Shake, K. L.; Mathis, J. T.

    2014-01-01

    The carbon dioxide (CO2)-carbonate chemistry of sea-ice melt and co-located, contemporaneous seawater has rarely been studied in sea ice covered oceans. Here, we describe the CO2-carbonate chemistry of sea-ice melt (both above sea ice as "melt ponds" and below sea ice as "interface waters") and mixed layer properties in the western Arctic Ocean in the early summer of 2010 and 2011. At nineteen stations, the salinity (~ 0.5 to < 6.5), dissolved inorganic carbon (DIC; ~ 20 to < 550 μmol kg-1) and total alkalinity (TA; ~ 30 to < 500 μmol kg-1) of above-ice melt pond water was low compared to water in the underlying mixed layer. The partial pressure of CO2 (pCO2) in these melt ponds was highly variable (~ < 10 to > 1500 μatm) with the majority of melt ponds acting as potentially strong sources of CO2 to the atmosphere. The pH of melt pond waters was also highly variable ranging from mildly acidic (6.1 to 7) to slightly more alkaline than underlying seawater (8 to 10.7). All of observed melt ponds had very low (< 0.1) saturation states (Ω) for calcium carbonate (CaCO3) minerals such as aragonite (Ωaragonite). Our data suggests that sea ice generated "alkaline" or "acidic" melt pond water. This melt-water chemistry dictates whether the ponds are sources of CO2 to the atmosphere or CO2 sinks. Below-ice interface water CO2-carbonate chemistry data also indicated substantial generation of alkalinity, presumably owing to dissolution of calcium CaCO3 in sea ice. The interface waters generally had lower pCO2 and higher pH/Ωaragonite than the co-located mixed layer beneath. Sea-ice melt thus contributed to the suppression of mixed layer pCO2 enhancing the surface ocean's capacity to uptake CO2 from the atmosphere. Meltwater contributions to changes in mixed-layer DIC were also used to estimate net community production rates (mean of 46.9 ±29.8 g C m-2 for the early-season period) under sea-ice cover. Although sea-ice melt is a transient seasonal feature, above-ice melt

  1. LDV measurements of turbulent baroclinic boundary layers

    SciTech Connect

    Neuwald, P.; Reichenbach, H.; Kuhl, A.L.

    1993-07-01

    Described here are shock tube experiments of nonsteady, turbulent boundary layers with large density variations. A dense-gas layer was created by injecting Freon through the porous floor of the shock tube. As the shock front propagated along the layer, vorticity was created at the air-Freon interface by an inviscid, baroclinic mechanism. Shadow-schlieren photography was used to visualize the turbulent mixing in this baroclinic boundary layer. Laser-Doppler-Velocimetry (LDV) was used to measure the streamwise velocity histories at 14 heights. After transition, the boundary layer profiles may be approximated by a power-law function u {approximately} u{sup {alpha}} where {alpha} {approx_equal} 3/8. This value lies between the clean flat plate value ({alpha} = 1/7) and the dusty boundary layer value ({alpha} {approx_equal} 0.7), and is controlled by the gas density near the wall.

  2. Lidar observation of elevated pollution layers over Los Angeles

    SciTech Connect

    Wakimoto, R.M.; McElroy, J.L.

    1986-11-01

    Elevated pollution layers are observed over Los Angeles with an aircraft equipped with a downward-looking lidar. For the first time, detailed ancillary upper-air kinematic and thermodynamic data were collected simultaneously to aid in the interpretation of these elevated layers. It is concluded that upper-level winds within the inversion, orographic effects, and thermally induced changes in the depth of the mixed layer control the evolution of these layers.

  3. Entrainment region phenomena for a large plane shear layer

    NASA Technical Reports Server (NTRS)

    Ali, S. K.; Klewicki, C. L.; Disimile, P. J.; Lawson, I.; Foss, J. F.

    1985-01-01

    The subatmospheric test section of the present free shear layer facility allows the entrainment air to be introduced with a negligible disturbance level. The very low frequency oscillations, which are prominently observed in the entrainment stream and which are present throughout the shear layer, are attributed to an inherent instability in the transition from a boundary layer to a free shear layer state. The basic features of the disturbance field are documented herein.

  4. Air transparent soundproof window

    SciTech Connect

    Kim, Sang-Hoon; Lee, Seong-Hyun

    2014-11-15

    A soundproof window or wall which is transparent to airflow is presented. The design is based on two wave theories: the theory of diffraction and the theory of acoustic metamaterials. It consists of a three-dimensional array of strong diffraction-type resonators with many holes centered on each individual resonator. The negative effective bulk modulus of the resonators produces evanescent wave, and at the same time the air holes with subwavelength diameter existed on the surfaces of the window for macroscopic air ventilation. The acoustic performance levels of two soundproof windows with air holes of 20mm and 50mm diameters were measured. The sound level was reduced by about 30 - 35dB in the frequency range of 400 - 5,000Hz with the 20mm window, and by about 20 - 35dB in the frequency range of 700 - 2,200Hz with the 50mm window. Multi stop-band was created by the multi-layers of the window. The attenuation length or the thickness of the window was limited by background noise. The effectiveness of the soundproof window with airflow was demonstrated by a real installation.

  5. [Air pollution].

    PubMed

    Bauters, Christophe; Bauters, Gautier

    2016-01-01

    Short-term exposure to particulate matter (PM) air pollution is associated with an increased cardiovascular mortality. Chronic exposure to PM is also associated with cardiovascular risk. Myocardial infarction and heart failure are the most common cardiovascular events associated with PM pollution. The pathophysiological mechanisms related to PM pollution are inflammation, thrombosis, vasomotion abnormalities, progression of atherosclerosis, increased blood pressure, and cardiac remodeling. A decrease in PM exposure may be particularly beneficial in subjects with a high cardiovascular risk. PMID:26547674

  6. Air filtering device

    SciTech Connect

    Backus, A.L.

    1992-07-28

    This patent describes a room air cleaning device. It comprises: a box housing having an air inlet and an air outlet provided therein; a vertical baffle coupled to the box housing opposite the air outlet and spaced form the box housing such that an air egress outlet is formed between the vertical baffle and the box housing; air cleansing means substantially disposed within the box housing and cleansing air passing into the inlet and out of the air egress outlet; a fan disposed within the box housing, the fan providing air movement through the air inlet and the air egress outlet; wherein air exits the room air cleaning device through the air egress outlet as a vertical plane of moving air; and wherein formation of the vertical plane of moving air contributes to the formation of a low pressure area drawing impure air toward the air inlet.

  7. Airborne Sunphotometry of African Dust and Marine Boundary Layer Aerosols in PRIDE

    NASA Technical Reports Server (NTRS)

    Livingston, John M.; Redemann, Jens; Russell, Philip; Schmid, Beat; Reid, Jeff; Pilewskie, Peter; Hipskind, R. Stephen (Technical Monitor)

    2000-01-01

    The Puerto Rico Dust Experiment (PRIDE) was conducted during summer 2000 to study the radiative, microphysical and transport properties of Saharan dust in the Caribbean region. During PRIDE, NASA Ames Research Center's six-channel airborne autotracking sunphotometer (AATS-6) was operated aboard a Piper Navajo airplane based at Roosevelt Roads Naval Station on the northeast coast of Puerto Rico. AATS-6 measurements were taken during 21 science flights off the coast of Puerto Rico in the western Caribbean. Data were acquired within and above the Marine Boundary Layer (MBL) and the Saharan Aerosol Layer (SAL) up to 5.5 km altitude tinder a wide range of dust loadings. Aerosol optical depth (AOD) spectra and columnar water vapor (CWV) values have been calculated from the AATS-6 measurements by using sunphotometer calibration data obtained at Mauna Loa Observatory (3A kin ASL) before (May) and after (October) PRIDE. Mid-visible AOD values measured near the surface during PRIDE ranged from 0.07 on the cleanest day to 0.55 on the most turbid day. Values measured above the MBL were as high as 0.35; values above the SAL were as low as 0.01. The fraction of total column AOD due to Saharan dust cannot be determined precisely from AATS-6 AOD data alone due to the uncertainty in the extent of vertical mixing of the dust down through the MBL. However, analyses of ground-based and airborne in-situ aerosol sampling measurements and ground-based aerosol lidar backscatter data should yield accurate characterization of the vertical mixing that will enable calculation of the Saharan dust AOD component from the sunphotometer data. Examples will be presented showing measured AATS-6 AOD spectra, calculated aerosol extinction and water vapor density vertical profiles, and aerosol size distributions retrieved by inversion of the AOD spectra. Near sea-surface AOD spectra acquired by AATS-6 during horizontal flight legs at 30 m ASL are available for validation of AOD derived from coincident

  8. S-layer-supported lipid membranes.

    PubMed

    Schuster, B; Sleytr, U B

    2000-09-01

    Many prokaryotic organisms (archaea and bacteria) are covered by a regularly ordered surface layer (S-layer) as the outermost cell wall component. S-layers are built up of a single protein or glycoprotein species and represent the simplest biological membrane developed during evolution. Pores in S-layers are of regular size and morphology, and functional groups on the protein lattice are aligned in well-defined positions and orientations. Due to the high degree of structural regularity S-layers represent unique systems for studying the structure, morphogenesis, and function of layered supramolecular assemblies. Isolated S-layer subunits of numerous organisms are able to assemble into monomolecular arrays either in suspension, at air/water interfaces, on planar mono- and bilayer lipid films, on liposomes and on solid supports (e.g. silicon wafers). Detailed studies on composite S-layer/lipid structures have been performed with Langmuir films, freestanding bilayer lipid membranes, solid supported lipid membranes, and liposomes. Lipid molecules in planar films and liposomes interact via their head groups with defined domains on the S-layer lattice. Electrostatic interactions are the most prevalent forces. The hydrophobic chains of the lipid monolayers are almost unaffected by the attachment of the S-layer and no impact on the hydrophobic thickness of the membranes has been observed. Upon crystallization of a coherent S-layer lattice on planar and vesicular lipid membranes, an increase in molecular order is observed, which is reflected in a decrease of the membrane tension and an enhanced mobility of probe molecules within an S-layer-supported bilayer. Thus, the terminology 'semifluid membrane' has been introduced for describing S-layer-supported lipid membranes. The most important feature of composite S-layer/lipid membranes is an enhanced stability in comparison to unsupported membranes. PMID:11143799

  9. A Proposal of Evaluation of Frost Layer Thickness

    NASA Astrophysics Data System (ADS)

    Yotsumoto, Hiroyuki; Ishihara, Isao; Tanio, Kenichi; Matsumoto, Ryosuke

    The frosting is an unsteady phenomenon occurs simultaneously with heat and mass transfer. Both the heat and water vapor in the humid air reach the surface of the frost layer and transfer to the cold surface. The frost surface plays an important role as an interface of heat and mass transfer between air-flow and ice-air composite solid layer. However, since the frost layer surface consists of ice and air, and is rough and unsteady, any specific definition of the frost layer thickness is not found. This paper tried to give the definition. The frost layer thickness was measured by using a micro photo-sensing device combined with a light emitter and receiver traversing normal to the frost surface. During traversing the device, a peak response from the device indicates the vertical position corresponding to the maximum frost area exposed to the emitted light i.e. air around the frost inside the frost layer. This position is defined as the frost layer position and it could give an effective frost layer.

  10. Laminar boundary layer in conditions of natural transition to turbulent flow

    NASA Technical Reports Server (NTRS)

    Polyakov, N. F.

    1986-01-01

    Results of experimental study of regularities of a natural transition of a laminar boundary layer to a turbulent layer at low subsonic air flow velocities are presented, analyzed and compared with theory and model experiments.

  11. Shear layer excitation, experiment versus theory

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.; Stahl, B.

    1984-01-01

    The acoustical excitation of shear layers is investigated. Acoustical excitation causes the so-called orderly structures in shear layers and jets. Also, the deviations in the spreading rate between different shear layer experiments are due to the same excitation mechanism. Measurements in the linear interaction region close to the edge from which the shear layer is shed are examined. Two sets of experiments (Houston 1981 and Berlin 1983/84) are discussed. The measurements were carried out with shear layers in air using hot wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

  12. AIR CLEANING FOR ACCEPTABLE INDOOR AIR QUALITY

    EPA Science Inventory

    The paper discusses air cleaning for acceptable indoor air quality. ir cleaning has performed an important role in heating, ventilation, and air-conditioning systems for many years. raditionally, general ventilation air-filtration equipment has been used to protect cooling coils ...

  13. Lidar observations of mixed layer dynamics - Tests of parameterized entrainment models of mixed layer growth rate

    NASA Technical Reports Server (NTRS)

    Boers, R.; Eloranta, E. W.; Coulter, R. L.

    1984-01-01

    Ground based lidar measurements of the atmospheric mixed layer depth, the entrainment zone depth and the wind speed and wind direction were used to test various parameterized entrainment models of mixed layer growth rate. Six case studies under clear air convective conditions over flat terrain in central Illinois are presented. It is shown that surface heating alone accounts for a major portion of the rise of the mixed layer on all days. A new set of entrainment model constants was determined which optimized height predictions for the dataset. Under convective conditions, the shape of the mixed layer height prediction curves closely resembled the observed shapes. Under conditions when significant wind shear was present, the shape of the height prediction curve departed from the data suggesting deficiencies in the parameterization of shear production. Development of small cumulus clouds on top of the layer is shown to affect mixed layer depths in the afternoon growth phase.

  14. Oxygen inhibition layer of composite resins: effects of layer thickness and surface layer treatment on the interlayer bond strength.

    PubMed

    Bijelic-Donova, Jasmina; Garoushi, Sufyan; Lassila, Lippo V J; Vallittu, Pekka K

    2015-02-01

    An oxygen inhibition layer develops on surfaces exposed to air during polymerization of particulate filling composite. This study assessed the thickness of the oxygen inhibition layer of short-fiber-reinforced composite in comparison with conventional particulate filling composites. The effect of an oxygen inhibition layer on the shear bond strength of incrementally placed particulate filling composite layers was also evaluated. Four different restorative composites were selected: everX Posterior (a short-fiber-reinforced composite), Z250, SupremeXT, and Silorane. All composites were evaluated regarding the thickness of the oxygen inhibition layer and for shear bond strength. An equal amount of each composite was polymerized in air between two glass plates and the thickness of the oxygen inhibition layer was measured using a stereomicroscope. Cylindrical-shaped specimens were prepared for measurement of shear bond strength by placing incrementally two layers of the same composite material. Before applying the second composite layer, the first increment's bonding site was treated as follows: grinding with 1,000-grit silicon-carbide (SiC) abrasive paper, or treatment with ethanol or with water-spray. The inhibition depth was lowest (11.6 μm) for water-sprayed Silorane and greatest (22.9 μm) for the water-sprayed short-fiber-reinforced composite. The shear bond strength ranged from 5.8 MPa (ground Silorane) to 36.4 MPa (water-sprayed SupremeXT). The presence of an oxygen inhibition layer enhanced the interlayer shear bond strength of all investigated materials, but its absence resulted in cohesive and mixed failures only with the short-fiber-reinforced composite. Thus, more durable adhesion with short-fiber-reinforced composite is expected. PMID:25556290

  15. Bioinspired air-retaining nanofur for drag reduction.

    PubMed

    Kavalenka, Maryna N; Vüllers, Felix; Lischker, Simone; Zeiger, Claudia; Hopf, Andreas; Röhrig, Michael; Rapp, Bastian E; Worgull, Matthias; Hölscher, Hendrik

    2015-05-27

    Bioinspired nanofur, covered by a dense layer of randomly distributed high aspect ratio nano- and microhairs, possesses superhydrophobic and air-retaining properties. Nanofur is fabricated using a highly scalable hot pulling method in which softened polymer is elongated with a heated sandblasted plate. Here we investigate the stability of the underwater air layer retained by the irregular nanofur topography by applying hydraulic pressure to the nanofur kept underwater, and evaluate the gradual changes in the air-covered area. Furthermore, the drag reduction resulting from the nanofur air retention is characterized by measuring the pressure drop across channels with and without nanofur. PMID:25945543

  16. Relevance of spontaneous fabT mutations to a streptococcal toxic shock syndrome to non-streptococcal toxic shock syndrome transition in the novel-type Streptococcus pyogenes isolates that lost a salRK.

    PubMed

    Tatsuno, Ichiro; Okada, Ryo; Matsumoto, Masakado; Hata, Nanako; Matsui, Hideyuki; Zhang, Yan; Isaka, Masanori; Hasegawa, Tadao

    2016-05-01

    Streptococcus pyogenes is a causative agent of streptococcal toxic shock syndrome (STSS). Mutations in covR/S or rgg, negative regulators, can reportedly modulate the severity of infection in this pathogen. Recently, we showed that the regions encoding the SalR-SalK, a two-component regulatory system, were deleted in some emm 1-type isolates (named as 'novel-type'). In this study, the two novel 'STSS' isolates 10-85stss and 11-171stss were more virulent than the two novel 'non-STSS' isolates 11O-2non and 11T-3non when examined using a mouse model of invasive infection. Genome-sequencing experiments using the three strains 10-85stss , 11-171stss , and 11O-2non detected only one single nucleotide polymorphism that causes a non-synonymous mutation in fabT encoding a transcriptional regulator in strain 11O-2non . Loss of fabT reduced the high level of virulence observed in the STSS isolates to that in the non-STSS isolates, and introduction of an intact fabT compensated the lower virulence of 11O-2non , suggesting that the mutation in fabT, but not in covR/S or rgg, is involved in the differential virulence among the novel-type clinical isolates. This type of non-synonymous fabT mutation was also identified in 12 non-STSS isolates (including 11O-2non and 11T-3non ), and most of those 12 isolates showed impaired FabT function. PMID:26861052

  17. Reassembly of S-layer proteins

    NASA Astrophysics Data System (ADS)

    Pum, Dietmar; Sleytr, Uwe B.

    2014-08-01

    Crystalline bacterial cell surface layers (S-layers) represent the outermost cell envelope component in a broad range of bacteria and archaea. They are monomolecular arrays composed of a single protein or glycoprotein species and represent the simplest biological membranes developed during evolution. They are highly porous protein mesh works with unit cell sizes in the range of 3 to 30 nm, and pore sizes of 2 to 8 nm. S-layers are usually 5 to 20 nm thick (in archaea, up to 70 nm). S-layer proteins are one of the most abundant biopolymers on earth. One of their key features, and the focus of this review, is the intrinsic capability of isolated native and recombinant S-layer proteins to form self-assembled mono- or double layers in suspension, at solid supports, the air-water interface, planar lipid films, liposomes, nanocapsules, and nanoparticles. The reassembly is entropy-driven and a fascinating example of matrix assembly following a multistage, non-classical pathway in which the process of S-layer protein folding is directly linked with assembly into extended clusters. Moreover, basic research on the structure, synthesis, genetics, assembly, and function of S-layer proteins laid the foundation for their application in novel approaches in biotechnology, biomimetics, synthetic biology, and nanotechnology.

  18. Ozone Layer Protection

    MedlinePlus

    ... menu Learn the Issues Air Chemicals and Toxics Climate Change Emergencies Greener Living Health and Safety Land and Cleanup Pesticides Waste Water Science & Technology Air Climate Change Ecosystems Health Land, Waste and Cleanup Pesticides Substances ...

  19. Acoustic radar investigations of boundary layer phenomena

    NASA Technical Reports Server (NTRS)

    Marks, J. R.

    1974-01-01

    A comparison is made between acoustic radar echoes and conventional meteorological data obtained from the WKY tower, for the purpose of better understanding the relationships between acoustic radar echoes and boundary layer processes. Two thunderstorm outflow cases are presented and compared to both acoustic radar data and Charba's gust front model. The acoustic radar echoes reveal the boundary between warm and cold air and other areas of mixing and strong thermal gradient quite well. The thunderstorm outflow of 27 June 1972 is found to compare with in most respects to Charba's gust front model. The major difference is the complete separation of the head from the main body of cold air, probably caused by erosion of the area behind the head by mixing with the ambient air. Two cases of nocturnal inversions caused by advection of warmer air aloft are presented. It is found that areas of turbulent mixing or strong thermal gradient can be identified quite easily in the acoustic radar record.

  20. 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.

  1. Transport of contaminants in the planetary boundary layer

    NASA Technical Reports Server (NTRS)

    Lee, I. Y.; Swan, P. R.

    1978-01-01

    A planetary boundary layer model is described and used to simulate PBL phenomena including cloud formation and pollution transport in the San Francisco Bay Area. The effect of events in the PBL on air pollution is considered, and governing equations for the average momentum, potential temperature, water vapor mixing ratio, and air contaminants are presented. These equations are derived by integrating the basic equations vertically through the mixed layer. Characteristics of the day selected for simulation are reported, and the results suggest that the diurnally cyclic features of the mesoscale motion, including clouds and air pollution, can be simulated in a readily interpretable way with the model.

  2. 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...

  3. Modelling Layer parallel stylolites

    NASA Astrophysics Data System (ADS)

    Koehn, Daniel; Pataki Rood, Daisy; Beaudoin, Nicolas

    2016-04-01

    We modeled the geometrical roughening of mainly layer-dominated stylolites in order to understand their structural evolution, to present an advanced classification of stylolite shapes and to relate this classification to chemical compaction and stylolite sealing capabilities. Our simulations show that layer-dominated stylolites can grow in three distinct stages, an initial slow nucleation, a fast layer-pinning phase and a final freezing stage if the layer dissolves completely during growth. Dissolution of the pinning layer and thus destruction of the compaction tracking capabilities is a function of the background noise in the rock and the dissolution rate of the layer itself. Low background noise needs a slower dissolving layer for pinning to be successful but produces flatter teeth than higher background noise. We present an advanced classification based on our simulations and separate stylolites into four classes: rectangular layer type, seismogram pinning type, suture/sharp peak type and simple wave-like type.

  4. Air pollution modeling and its application III

    SciTech Connect

    De Wispelaere, C.

    1984-01-01

    This book focuses on the Lagrangian modeling of air pollution. Modeling cooling tower and power plant plumes, modeling the dispersion of heavy gases, remote sensing as a tool for air pollution modeling, dispersion modeling including photochemistry, and the evaluation of model performances in practical applications are discussed. Specific topics considered include dispersion in the convective boundary layer, the application of personal computers to Lagrangian modeling, the dynamic interaction of cooling tower and stack plumes, the diffusion of heavy gases, correlation spectrometry as a tool for mesoscale air pollution modeling, Doppler acoustic sounding, tetroon flights, photochemical air quality simulation modeling, acid deposition of photochemical oxidation products, atmospheric diffusion modeling, applications of an integral plume rise model, and the estimation of diffuse hydrocarbon leakages from petrochemical factories. This volume constitutes the proceedings of the Thirteenth International Technical Meeting on Air Pollution Modeling and Its Application held in France in 1982.

  5. Joint Air Sea Interaction (JASIN) experiment, Northwest coast of Scotland

    NASA Technical Reports Server (NTRS)

    Businger, J. A.

    1981-01-01

    The joint air sea interaction (JASIN) experiment took place off the Northwest coast of Scotland. Sea surface and boundary layer parameters were measured. The JASIN data was used as ground truth for various sensors on the SEASAT satellite.

  6. IET. Stack interior. Masons lay fire brick liner, leaving air ...

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

    IET. Stack interior. Masons lay fire brick liner, leaving air layer between bricks and concrete wall. Date: May 20, 1955. INEEL negative no. 55-1306 - Idaho National Engineering Laboratory, Test Area North, Scoville, Butte County, ID

  7. A FEDERATED PARTNERSHIP FOR URBAN METEOROLOGICAL AND AIR QUALITY MODELING

    EPA Science Inventory

    Recently, applications of urban meteorological and air quality models have been performed at resolutions on the order of km grid sizes. This necessitated development and incorporation of high resolution landcover data and additional boundary layer parameters that serve to descri...

  8. High efficiency air cycle air conditioning system

    SciTech Connect

    Rannenberg, G. C.

    1985-11-19

    An air cycle air conditioning system is provided with regenerative heat exchangers upstream and downstream of an expansion turbine. A closedloop liquid circulatory system serially connects the two regenerative heat exchangers for regeneration without the bulk associated with air-to-air heat exchange. The liquid circulatory system may also provide heat transport to a remote sink heat exchanger and from a remote load as well as heat exchange within the sink heat exchanger and load for enhanced compactness and efficiency.

  9. Layer-by-layer cell membrane assembly

    NASA Astrophysics Data System (ADS)

    Matosevic, Sandro; Paegel, Brian M.

    2013-11-01

    Eukaryotic subcellular membrane systems, such as the nuclear envelope or endoplasmic reticulum, present a rich array of architecturally and compositionally complex supramolecular targets that are as yet inaccessible. Here we describe layer-by-layer phospholipid membrane assembly on microfluidic droplets, a route to structures with defined compositional asymmetry and lamellarity. Starting with phospholipid-stabilized water-in-oil droplets trapped in a static droplet array, lipid monolayer deposition proceeds as oil/water-phase boundaries pass over the droplets. Unilamellar vesicles assembled layer-by-layer support functional insertion both of purified and of in situ expressed membrane proteins. Synthesis and chemical probing of asymmetric unilamellar and double-bilayer vesicles demonstrate the programmability of both membrane lamellarity and lipid-leaflet composition during assembly. The immobilized vesicle arrays are a pragmatic experimental platform for biophysical studies of membranes and their associated proteins, particularly complexes that assemble and function in multilamellar contexts in vivo.

  10. Healthy Air Outdoors

    MedlinePlus

    ... clean up the air are enforced. Learn more Climate Change Climate change threatens the health of millions of people, with ... What Makes Air Unhealthy Fighting for Healthy Air Climate Change Emergencies & Natural Disasters Tobacco Education and Training Ask ...

  11. HEPA air filter (image)

    MedlinePlus

    ... pet dander and other irritating allergens from the air. Along with other methods to reduce allergens, such ... controlling the amount of allergens circulating in the air. HEPA filters can be found in most air ...

  12. Needed: Clean Air.

    ERIC Educational Resources Information Center

    Schneider, Gerald

    1979-01-01

    Provides information on air pollution for young readers. Discusses damage to substances and sickness from air pollution, air quality, and what to do in a pollution alert. Includes questions with answers, illustrations, and activities for the learner. (MA)

  13. Photonic layered media

    DOEpatents

    Fleming, James G.; Lin, Shawn-Yu

    2002-01-01

    A new class of structured dielectric media which exhibit significant photonic bandstructure has been invented. The new structures, called photonic layered media, are easy to fabricate using existing layer-by-layer growth techniques, and offer the ability to significantly extend our practical ability to tailor the properties of such optical materials.

  14. Primary zone air proportioner

    DOEpatents

    Cleary, Edward N. G.

    1982-10-12

    An air proportioner is provided for a liquid hydrocarbon fueled gas turbine of the type which is convertible to oil gas fuel and to coal gas fuel. The turbine includes a shell for enclosing the turbine, an air duct for venting air in said shell to a gasifier, and a fuel injector for injecting gasified fuel into the turbine. The air proportioner comprises a second air duct for venting air from the air duct for mixing with fuel from the gasifier. The air can be directly injected into the gas combustion basket along with the fuel from the injector or premixed with fuel from the gasifier prior to injection by the fuel injector.

  15. The dynamic F2-layer over Arecibo

    NASA Technical Reports Server (NTRS)

    Ganguly, S.; Walker, J. C. G.; Rishbeth, H.

    1980-01-01

    The idealized 'servo' model of the ionospheric F2-layer of Rishbeth et al. (1978) is used to simulate the observed behavior of the daytime Fe-peak at Arecibo at sunspot minimum. The meridional pressure-gradient force associated with the meridional neutral-air wind is determined empirically. The local time variation during the day is found to be consistent with the semidiurnal variation given by the MSIS atmospheric model of Hedin et al. (1977). The values of the F2-layer loss and diffusion coefficients needed to match the data are broadly consistent with the MSIS model.

  16. Scintillator reflective layer coextrusion

    SciTech Connect

    Yun, Jae-Chul; Para, Adam

    2001-01-01

    A polymeric scintillator has a reflective layer adhered to the exterior surface thereof. The reflective layer comprises a reflective pigment and an adhesive binder. The adhesive binder includes polymeric material from which the scintillator is formed. A method of forming the polymeric scintillator having a reflective layer adhered to the exterior surface thereof is also provided. The method includes the steps of (a) extruding an inner core member from a first amount of polymeric scintillator material, and (b) coextruding an outer reflective layer on the exterior surface of the inner core member. The outer reflective layer comprises a reflective pigment and a second amount of the polymeric scintillator material.

  17. CALIPSO Observations of Transatlantic Dust: Vertical Stratification and Effect of Clouds

    NASA Technical Reports Server (NTRS)

    Yang, Weidong; Marshak, Alexander; Varnai, Tamas; Kalashnikova, Olga V.; Kostinski, Alexander B.

    2012-01-01

    CALIOP nighttime measurements of lidar backscatter, color and depolarization ratios during the summer of 2007 are used to study transatlantic dust properties downwind of Saharan sources, and to examine the interaction of clouds and dust. We discuss the following findings: (1) while lidar backscatter doesn't change much with altitude in the Saharan Air Layer (SAL), depolarization and color ratios both increase with altitude in the SAL; (2) lidar backscatter and color ratio increase as dust is transported westward in the SAL; (3) the vertical lapse rate of dust depolarization ratio increases within SAL as plumes move westward; (4) nearby clouds barely affect the backscatter and color ratio of dust volumes within SAL but not so below SAL. Finally, (5) the odds of CALIOP finding dust below SAL next to clouds are about 2/3 of those far away from clouds. This feature, together with an apparent increase in depolarization ratio near clouds, indicates that particles in some dusty volumes lose asphericity in the humid air near clouds, and cannot be identified by CALIPSO as dust.

  18. CALIPSO Observations of Transatlantic Dust: Vertical Stratification and Effect of Clouds

    NASA Technical Reports Server (NTRS)

    Yang, Weidong; Marshak, Alexander; Varnai, Tamas; Kalashnikova, Olga V.; Kostinski, Alexander B.

    2014-01-01

    We use CALIOP nighttime measurements of lidar backscatter, color and depolarization ratios, as well as particulate retrievals during the summer of 2007 to study transatlantic dust properties downwind of Saharan sources, and to examine the influence of nearby clouds on dust. Our analysis suggests that (1) under clear skies, while lidar backscatter and color ratio do not change much with altitude and longitude in the Saharan Air Layer (SAL), depolarization ratio increases with altitude and decreases westward in the SAL (2) the vertical lapse rate of dust depolarization ratio, introduced here, increases within SAL as plumes move westward (3) nearby clouds barely affect the backscatter and color ratio of dust volumes within SAL but not so below SAL. Moreover, the presence of nearby clouds tends to decrease the depolarization of dust volumes within SAL. Finally, (4) the odds of CALIOP finding dust below SAL next to clouds are about of those far away from clouds. This feature, together with an apparent increase in depolarization ratio near clouds, indicates that particles in some dust volumes loose asphericity in the humid air near clouds, and cannot be identified by CALIPSO as dust.

  19. Visual air quality simulation techniques

    NASA Astrophysics Data System (ADS)

    Molenar, John V.; Malm, William C.; Johnson, Christopher E.

    Visual air quality is primarily a human perceptual phenomenon beginning with the transfer of image-forming information through an illuminated, scattering and absorbing atmosphere. Visibility, especially the visual appearance of industrial emissions or the degradation of a scenic view, is the principal atmospheric characteristic through which humans perceive air pollution, and is more sensitive to changing pollution levels than any other air pollution effect. Every attempt to quantify economic costs and benefits of air pollution has indicated that good visibility is a highly valued and desired environmental condition. Measurement programs can at best approximate the state of the ambient atmosphere at a few points in a scenic vista viewed by an observer. To fully understand the visual effect of various changes in the concentration and distribution of optically important atmospheric pollutants requires the use of aerosol and radiative transfer models. Communication of the output of these models to scientists, decision makers and the public is best done by applying modern image-processing systems to generate synthetic images representing the modeled air quality conditions. This combination of modeling techniques has been under development for the past 15 yr. Initially, visual air quality simulations were limited by a lack of computational power to simplified models depicting Gaussian plumes or uniform haze conditions. Recent explosive growth in low cost, high powered computer technology has allowed the development of sophisticated aerosol and radiative transfer models that incorporate realistic terrain, multiple scattering, non-uniform illumination, varying spatial distribution, concentration and optical properties of atmospheric constituents, and relative humidity effects on aerosol scattering properties. This paper discusses these improved models and image-processing techniques in detail. Results addressing uniform and non-uniform layered haze conditions in both

  20. Large Eddy Simulation of Stable Boundary Layer Turbulent Processes in Complex Terrain

    SciTech Connect

    Eric D. Skyllingstad

    2005-01-26

    Research was performed using a turbulence boundary layer model to study the behavior of cold, dense flows in regions of complex terrain. Results show that flows develop a balance between turbulent entrainment of warm ambient air and dense, cold air created by surface cooling. Flow depth and strength is a function of downslope distance, slope angle and angle changes, and the ambient air temperature.

  1. Experimental Investigation of Axisymmetric Transitional Shock Wave Boundary Layer Interactions at Mach 5

    NASA Astrophysics Data System (ADS)

    Erdem, E.; Kontis, K.; Johnstone, E.; Murray, N.; Steelant, J.

    Shock Wave Boundary Layer Interactions (SWBLIs) can induce separation which causes loss of a control surface effectiveness, drop of an air intake efficiency and it may be the origin of large scale fluctuations such as air-intake buzz, buffeting or fluctuating side loads in separated propulsive nozzles. The subsequent reattachment of the separated shear layer on a nearby surface gives rise to local heat transfer rates which can be far in excess of those of an attached boundary layer [1].

  2. Early Results from AIRS/AMSU/HSB

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Barnet, Christopher; Blaisdell, John; Iredell, Lena; Keita, Fricky; Kouvaris, Lou

    2003-01-01

    AIRS was launched on EOS Aqua on May 5, 2002, together with AMSU A and HSB, to form a next generation polar orbiting infiared and microwave atmospheric sounding system. The primary products of AIRS/AMSU/HSB are twice daily global fields of atmospheric temperature-humidity profiles, ozone profiles, sea/land surface skin temperature, and cloud related parameters including OLR. The sounding goals of AIRS are to produce 1 km tropospheric layer mean temperatures with an rms error of lK, and layer precipitable water with an rms error of 20%, in cases with up to 80% effective cloud cover. Pre-launch simulation studies indicated that these results should be achievable. Minor modifications have been made to the pre-launch retrieval algorithm as described in this paper. Sample fields of parameters retrieved from AIRS/AMSU/HSB data are presented and validated as a function of retrieved fractional cloud cover. As in simulation, the degradation of retrieval accuracy with increasing cloud cover is small. Select fields are also compared to those contained in the ECMWF analysis, done without the benefit of AIRS data, to demonstrate information that AIRS can add to that already contained in the ECMWF analysis.

  3. REACH. Air Conditioning Units.

    ERIC Educational Resources Information Center

    Garrison, Joe; And Others

    As a part of the REACH (Refrigeration, Electro-Mechanical, Air-Conditioning, Heating) electromechanical cluster, this student manual contains individualized instructional units in the area of air conditioning. The instructional units focus on air conditioning fundamentals, window air conditioning, system and installation, troubleshooting and…

  4. Building Air Monitoring Networks

    ERIC Educational Resources Information Center

    Environmental Science and Technology, 1977

    1977-01-01

    The different components of air monitoring networks, the status of air monitoring in the United States, and the services and activities of the three major American network builders are detailed. International air monitoring networks and alert systems are identified, with emphasis on the Dutch air monitoring network. (BT)

  5. The Clean Air Game.

    ERIC Educational Resources Information Center

    Avalone-King, Deborah

    2000-01-01

    Introduces the Clean Air game which teaches about air quality and its vital importance for life. Introduces students to air pollutants, health of people and environment, and possible actions individuals can take to prevent air pollution. Includes directions for the game. (YDS)

  6. Coating of porous carbon for use in lithium air batteries

    SciTech Connect

    Amine, Khalil; Lu, Jun; Du, Peng; Lei, Yu; Elam, Jeffrey W

    2015-04-14

    A cathode includes a carbon material having a surface, the surface having a first thin layer of an inert material and a first catalyst overlaying the first thin layer, the first catalyst including metal or metal oxide nanoparticles, wherein the cathode is configured for use as the cathode of a lithium-air battery.

  7. Layer Precipitable Water (LPW) Briefing

    NASA Technical Reports Server (NTRS)

    Forsythe, John; Kidder, Stan; Fuell, Kevin; LeRoy, Anita

    2013-01-01

    Microwave Integrated Retrieval System (MIRS) provides soundings of specific humidity from a variety of instruments and is combined with AIRS infrared soundings to create a Layered Precipitable Water (LPW) composite product. The LPW provides vertical moisture information in the column instead of just upper levels via WV imagery, or a single column value via TPW products. LPW is created every 3 hours using the last 12 hours worth of data and has a delivery latency of 40 minutes. Weaknesses include discontinuities in the composite. Strengths include seeing through clouds, over land usage, and greater spatial coverage of vertical moisture profiles. Applications of LPW include analysis of horizontal and vertical moisture gradients, verification of NWP moisture, and analysis of atmospheric rivers and other moisture advection. Operational testbed is ongoing to determine viability of wider distribution.

  8. The enhancement mechanism of thin plasma layer on antenna radiation

    SciTech Connect

    Wang, Chunsheng Jiang, Binhao; Li, Xueai

    2015-03-09

    A model of plasma-antenna is carried out to study the radiation enhancement mechanism of antenna covered by thin plasma layer. The results show when the radiation intensity achieves maximum, a region of equal electric field is formed due to the reflection of electric field at the interface of plasma and air. The plasma layer acted as an extension of the antenna. Furthermore, the shape of plasma layer is changed to verify the effect of plasma boundary on antenna radiation. The study shows the effect of thin plasma layer on electromagnetic field and provides a type of plasma antenna.

  9. Bifunctional air electrodes containing elemental iron powder charging additive

    DOEpatents

    Liu, Chia-tsun; Demczyk, Brian G.; Gongaware, Paul R.

    1982-01-01

    A bifunctional air electrode for use in electrochemical energy cells is made, comprising a hydrophilic layer and a hydrophobic layer, where the hydrophilic layer essentially comprises a hydrophilic composite which includes: (i) carbon; (ii) elemental iron particles having a particle size of between about 25 microns and about 700 microns diameter; (iii) an oxygen evolution material; (iv) a nonwetting agent; and (v) a catalyst, where at least one current collector is formed into said composite.

  10. Layered plasma polymer composite membranes

    DOEpatents

    Babcock, W.C.

    1994-10-11

    Layered plasma polymer composite fluid separation membranes are disclosed, which comprise alternating selective and permeable layers for a total of at least 2n layers, where n is [>=]2 and is the number of selective layers. 2 figs.

  11. Layers and Erosion and more Layers

    NASA Technical Reports Server (NTRS)

    2003-01-01

    [figure removed for brevity, see original site]

    Released 4 November 2003

    This image is located within a set of eroded layered rocks known as the Medusae Fossae Formation. Careful inspection of this image reveals four separate layers. Starting at the bottom of the image, as well as the bottom of the sequence of layers, is a somewhat hilly, cratered plain. Above that is a mud or lava flow with a lobate edge that is characteristic of fluid flow. Above that is a layer with a spectacular rayed crater. This layer shows linear erosional patterns that are probably caused by persistent wind abrasion, typical of rocks in this area. And finally, a more blocky unit lies on top, mostly eroded away.

    Image information: VIS instrument. Latitude 3.6, Longitude 218.6 East (141.4 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  12. Process for depositing Cr-bearing layer

    DOEpatents

    Ellis, T.W.; Lograsso, T.A.; Eshelman, M.A.

    1995-05-09

    A method of applying a Cr-bearing layer to a substrate, comprises introducing an organometallic compound, in vapor or solid powder form entrained in a carrier gas to a plasma of an inductively coupled plasma torch or device to thermally decompose the organometallic compound and contacting the plasma and the substrate to be coated so as to deposit the Cr-bearing layer on the substrate. A metallic Cr, Cr alloy or Cr compound such as chromium oxide, nitride and carbide can be provided on the substrate. Typically, the organometallic compound is introduced to an inductively coupled plasma torch that is disposed in ambient air so to thermally decompose the organometallic compound in the plasma. The plasma is directed at the substrate to deposit the Cr-bearing layer or coating on the substrate. 7 figs.

  13. Process for depositing Cr-bearing layer

    DOEpatents

    Ellis, Timothy W.; Lograsso, Thomas A.; Eshelman, Mark A.

    1995-05-09

    A method of applying a Cr-bearing layer to a substrate, comprises introducing an organometallic compound, in vapor or solid powder form entrained in a carrier gas to a plasma of an inductively coupled plasma torch or device to thermally decompose the organometallic compound and contacting the plasma and the substrate to be coated so as to deposit the Cr-bearing layer on the substrate. A metallic Cr, Cr alloy or Cr compound such as chromium oxide, nitride and carbide can be provided on the substrate. Typically, the organometallic compound is introduced to an inductively coupled plasma torch that is disposed in ambient air so to thermally decompose the organometallic compound in the plasma. The plasma is directed at the substrate to deposit the Cr-bearing layer or coating on the substrate.

  14. Merging of OMI and AIRS Ozone Data

    NASA Technical Reports Server (NTRS)

    Labow, Gordon J.; Fisher, Bradford; Susskind, Joel

    2014-01-01

    The OMI Instrument measures ozone using the backscattered light in the UV part of the spectrum. In polar night there are no OMI measurements so we hope to incorporate the AIRS ozone data to fill in these missing regions. AIRS is on the Aqua platform and has been operating since May 2002. AIRS is a multi-detector array grating spectrometer containing 2378 IR channels between 650 per centimeter and 2760 per centimeter which measures atmospheric temperature, precipitable water, water vapor, CO, CH4, CO2 and ozone profiles and column amount. It can also measure effective cloud fraction and cloud top pressure for up to two cloud layers and sea-land skin temperature. Since 2008, OMI has had part of its aperture occulted with a piece of the thermal blanket resulting in several scan positions being unusable. We hope to use the AIRS data to fill in the missing ozone values for those missing scan positions.

  15. Limitation of discharge capacity and mechanisms of air-electrode deactivation in silicon-air batteries.

    PubMed

    Jakes, Peter; Cohn, Gil; Ein-Eli, Yair; Scheiba, Frieder; Ehrenberg, Helmut; Eichel, Rüdiger-A

    2012-11-01

    The electrocatalytical process at the air cathode in novel silicon-air batteries using the room-temperature ionic liquid hydrophilic 1-ethyl-3-methylimidazolium oligofluorohydrogenate [EMI⋅2.3 HF⋅F] as electrolyte and highly doped silicon wafers as anodes is investigated by electrochemical means, X-ray photoelectron spectroscopy (XPS), and electron paramagnetic resonance (EPR) spectroscopy. The results obtained by XPS and EPR provide a model to describe the limited discharge capacity by means of a mechanism of air-electrode deactivation. In that respect, upon discharge the silicon-air battery's cathode is not only blocked by silicon oxide reduction products, but also experiences a major modification in the MnO₂ catalyst nature. The proposed modification of the MnO₂ catalyst by means of a MnF₂ surface layer greatly impacts the Si-air performance and describes a mechanism relevant for other metal-air batteries, such as the lithium-air. Moreover, the ability for this deactivation layer to form is greatly impacted by water in the electrolyte. PMID:23033259

  16. Three-dimensional freezing of flowing water in a tube cooled by air flow

    NASA Astrophysics Data System (ADS)

    Sugawara, M.; Komatsu, Y.; Beer, H.

    2015-05-01

    The 3-D freezing of flowing water in a copper tube cooled by air flow is investigated by means of a numerical analysis. The air flows normal to the tube axis. Several parameters as inlet water mean velocity w m , inlet water temperature T iℓ t , air flow temperature T a and air flow velocity u a are selected in the calculations to adapt it to a winter season actually encountered. The numerical results present the development of the ice layer mean thickness and its 3-D morphologies as well as the critical ice layer thickness in the tube choked by the ice layer.

  17. 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.

  18. Multiple density layered insulator

    DOEpatents

    Alger, T.W.

    1994-09-06

    A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.

  19. Multiple density layered insulator

    DOEpatents

    Alger, Terry W.

    1994-01-01

    A multiple density layered insulator for use with a laser is disclosed wh provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation.

  20. Substrate topography-mediated air film collapse below an impacting drop

    NASA Astrophysics Data System (ADS)

    de Ruiter, Jolet; van den Ende, Dirk; Mugele, Frieder

    2012-11-01

    Liquid drops hitting solid surfaces are slowed down by the ambient air layer that needs to be squeezed out before the liquid actually touches the solid. How does substrate topography mediate the collapse of the air film? For moderate velocity impacts (Weber number around unity) we show that a drop gently spreads on an undulated air layer that thins to a minimum of several hundreds of nanometers. Whether or not the air layer collapses (in a single spot nucleation) leading to wetting of the substrate, can be tuned with substrate topography. Introducing micro- and nanoscale defects of various topography, we observe the two different cases, i.e. drop bouncing on the air layer and directed nucleation of liquid-solid contact. Using quantitative dual wavelength reflection interference microscopy we reveal the evolution of the air film, and the influence of substrate defects on localized pressure build-up and film collapse.

  1. Air distribution in the Borden aquifer during in situ air sparging.

    PubMed

    Tomlinson, D W; Thomson, N R; Johnson, R L; Redman, J D

    2003-12-01

    A field experiment was conducted at Canadian Forces Base Borden (CFB Borden) to assess the air distribution from a single in situ air sparging injection point. This aquifer consists of fine to medium sand deposited in horizontal layers. The permeability at the study location varied from 10(-10) to 10(-14) m2 and distinct low permeability horizons were present at approximately 1.2, 2.0, and 2.9 m below the water table. Prior to air injection, a 15x15-m portion of the vadose zone was excavated to the water table (approximately 1 m below ground surface) in order to visually observe air release distribution at the water table. The water table was actively maintained 5 cm above the excavated surface. The sparging system operated for a period of 7 days with an injection flow rate of 200 m3/days (5 scfm). The resulting subsurface air distribution was assessed using a variety of techniques including neutron logging, borehole and surface ground penetrating radar, piezometric head measurements, surface visualization, and hydraulic testing. Through this combination of tests, it was demonstrated that variations in permeability and, hence, capillary pressure at the site were sufficient to cause the injected air to spread laterally, forming stratigraphically trapped air pockets beneath the low permeability horizons. The formation of these air pockets eventually resulted in a buildup of capillary pressure that exceeded the air entry pressure and allowed some air to migrate up through the lower permeability layers. Each of the assessment techniques employed generated information at different spatial scales that prevented a direct comparison of the results from the various techniques; however, the results from all techniques proved to be critical in the interpretation of the experimental data. As a consequence, the different assessment techniques should not be viewed as alternatives, but rather as complimentary techniques. PMID:14607473

  2. EASI - EQUILIBRIUM AIR SHOCK INTERFERENCE

    NASA Technical Reports Server (NTRS)

    Glass, C. E.

    1994-01-01

    New research on hypersonic vehicles, such as the National Aero-Space Plane (NASP), has raised concerns about the effects of shock-wave interference on various structural components of the craft. State-of-the-art aerothermal analysis software is inadequate to predict local flow and heat flux in areas of extremely high heat transfer, such as the surface impingement of an Edney-type supersonic jet. EASI revives and updates older computational methods for calculating inviscid flow field and maximum heating from shock wave interference. The program expands these methods to solve problems involving the six shock-wave interference patterns on a two-dimensional cylindrical leading edge with an equilibrium chemically reacting gas mixture (representing, for example, the scramjet cowl of the NASP). The inclusion of gas chemistry allows for a more accurate prediction of the maximum pressure and heating loads by accounting for the effects of high temperature on the air mixture. Caloric imperfections and specie dissociation of high-temperature air cause shock-wave angles, flow deflection angles, and thermodynamic properties to differ from those calculated by a calorically perfect gas model. EASI contains pressure- and temperature-dependent thermodynamic and transport properties to determine heating rates, and uses either a calorically perfect air model or an 11-specie, 7-reaction reacting air model at equilibrium with temperatures up to 15,000 K for the inviscid flowfield calculations. EASI solves the flow field and the associated maximum surface pressure and heat flux for the six common types of shock wave interference. Depending on the type of interference, the program solves for shock-wave/boundary-layer interaction, expansion-fan/boundary-layer interaction, attaching shear layer or supersonic jet impingement. Heat flux predictions require a knowledge (from experimental data or relevant calculations) of a pertinent length scale of the interaction. Output files contain flow

  3. Effect of particle settling on lidar profiles of long-range transported Saharan aerosols

    NASA Astrophysics Data System (ADS)

    Gasteiger, Josef; Groß, Silke

    2016-04-01

    A large amount of desert aerosol is transported in the Saharan Air Layer (SAL) westwards from Africa over the Atlantic Ocean. Lidar profiles of transported Saharan aerosol may contain some information about the vertically-resolved aerosol microphysics that could be used to characterize processes that affected the measured aerosol during transport. We present modelled lidar profiles of long-range transported Saharan aerosol assuming that initially the SAL is well-mixed and that there is no vertical mixing of air within the SAL as soon as it reaches the Atlantic. We consider Stokes gravitational settling of aerosol particles over the ocean. The lidar profiles are calculated using optical models for irregularly-shaped mineral dust particles assuming settling-induced particle removal as function of distance from the SAL top. Within the SAL we find a decrease of both the backscatter coefficients and the linear depolarization ratios with decreasing distance from the SAL top. For example, the linear depolarization ratio at a wavelength of 532nm decreases from 0.289 at 1000m to 0.256 at 200m and 0.215 at 100m below SAL top. We compare the modelled backscatter coefficients and linear depolarization ratios to ground-based lidar measurements performed during the SALTRACE field campaign in Barbados (Caribbean) and find agreement within the estimated uncertainties. We discuss the uncertainties of our modeling approach in our presentation. Assumed mineral dust particle shapes, assumed particle mixture properties, and assumptions about processes in the SAL over the continent and the ocean are important aspects to be considered. Uncertainties are relevant for the potential of lidar measurements of transported Saharan dust to learn something about processes occuring in the SAL during long-range transport. We also compare our modeling results to modeling results previously published in the literature.

  4. Boosting water oxidation layer-by-layer.

    PubMed

    Hidalgo-Acosta, Jonnathan C; Scanlon, Micheál D; Méndez, Manuel A; Amstutz, Véronique; Vrubel, Heron; Opallo, Marcin; Girault, Hubert H

    2016-04-01

    Electrocatalysis of water oxidation was achieved using fluorinated tin oxide (FTO) electrodes modified with layer-by-layer deposited films consisting of bilayers of negatively charged citrate-stabilized IrO2 NPs and positively charged poly(diallyldimethylammonium chloride) (PDDA) polymer. The IrO2 NP surface coverage can be fine-tuned by controlling the number of bilayers. The IrO2 NP films were amorphous, with the NPs therein being well-dispersed and retaining their as-synthesized shape and sizes. UV/vis spectroscopic and spectro-electrochemical studies confirmed that the total surface coverage and electrochemically addressable surface coverage of IrO2 NPs increased linearly with the number of bilayers up to 10 bilayers. The voltammetry of the modified electrode was that of hydrous iridium oxide films (HIROFs) with an observed super-Nernstian pH response of the Ir(III)/Ir(IV) and Ir(IV)-Ir(IV)/Ir(IV)-Ir(V) redox transitions and Nernstian shift of the oxygen evolution onset potential. The overpotential of the oxygen evolution reaction (OER) was essentially pH independent, varying only from 0.22 V to 0.28 V (at a current density of 0.1 mA cm(-2)), moving from acidic to alkaline conditions. Bulk electrolysis experiments revealed that the IrO2/PDDA films were stable and adherent under acidic and neutral conditions but degraded in alkaline solutions. Oxygen was evolved with Faradaic efficiencies approaching 100% under acidic (pH 1) and neutral (pH 7) conditions, and 88% in alkaline solutions (pH 13). This layer-by-layer approach forms the basis of future large-scale OER electrode development using ink-jet printing technology. PMID:26977761

  5. Desiccant Enhanced Evaporative Air Conditioning: Parametric Analysis and Design; Preprint

    SciTech Connect

    Woods, J.; Kozubal, E.

    2012-10-01

    This paper presents a parametric analysis using a numerical model of a new concept in desiccant and evaporative air conditioning. The concept consists of two stages: a liquid desiccant dehumidifier and a dew-point evaporative cooler. Each stage consists of stacked air channel pairs separated by a plastic sheet. In the first stage, a liquid desiccant film removes moisture from the process (supply-side) air through a membrane. An evaporatively-cooled exhaust airstream on the other side of the plastic sheet cools the desiccant. The second-stage indirect evaporative cooler sensibly cools the dried process air. We analyze the tradeoff between device size and energy efficiency. This tradeoff depends strongly on process air channel thicknesses, the ratio of first-stage to second-stage area, and the second-stage exhaust air flow rate. A sensitivity analysis reiterates the importance of the process air boundary layers and suggests a need for increasing airside heat and mass transfer enhancements.

  6. Air volume measurement of 'Braeburn' apple fruit.

    PubMed

    Drazeta, Lazar; Lang, Alexander; Hall, Alistair J; Volz, Richard K; Jameson, Paula E

    2004-05-01

    The radial disposition of air in the flesh of fruit of Malus domestica Borkh., cv 'Braeburn' was investigated using a gravimetric technique based on Archimedes' principle. Intercellular air volume was measured by weighing a small tissue sample under water before and after vacuum infiltration to remove the air. In a separate procedure, the volume of the same sample was measured by recording the buoyant upthrust experienced by it when fully immersed in water. The method underestimates tissue air volume due to a slight invasion of the intercellular air spaces around the edges of the sample when it is immersed in water. To correct for this error, an adjustment factor was made based upon an analysis of a series of measurements of air volume in samples of different dimensions. In 'Braeburn' there is a gradient of declining air content from just beneath the skin to the centre of the fruit with a sharp discontinuity at the core line. Cell shape and cell packing were observed in the surface layers of freshly excised and stained flesh samples using a dissecting microscope coupled to a video camera and a PC running proprietary software. Tissue organization changed with distance below the skin. It is speculated that reduced internal gas movement, due to the tightly packed tissue of 'Braeburn' and to the potential diffusion barrier at the core line between the cortex and the pith, may increase susceptibility of the flesh to disorders associated with tissue browning and breakdown. PMID:15047764

  7. NewChallengesThreateningtheOzoneLayer

    NASA Astrophysics Data System (ADS)

    Abubakar, B.

    2007-05-01

    Since the beginning of the 1990's when the importation of fairly used Refrigerators, Air-conditioners and propellants that can easily go broken containing chlorofluorocarbon substances that is capable of destroying the Ozone layer started in commercial quantity in Africa, the African refuse mountains began metamorphosing into mountains of dumped broken Refrigerators, Air-conditioners and Propellants which are collectively becoming a threat to the Ozone layer, because of the continuous discharging of the Chlorofluorocarbon gases by the refuse in to the atmosphere in each passing second.. Nobody can actually quantify the numbers of Refrigerators, Air-conditioners and Propellants imported and disposed in Africa over the last fifteen years, but the facts still remains that the numbers of metamorphosing mountains keeps on increasing in both size and numbers in each passing day. They have even become sources of raw materials for the local blacksmiths, children and refrigerators repairers who use parts of the dumped refrigerators, Air-conditioners and Propellants for their constructions, toys and repairs respectively. This explains the reason why despite the global efforts toward protecting the Ozone layer by the United Nations (UN), governments, International Organizations and climatologist among many others, but yet the hole in the Ozone layer keeps on expanding and the global temperature keeps on rising which resulted in the unusual phenomenon like the hurricanes "Katrina" and "Rita" the unusual floods in China, Thailand, Mozambique and to some extent even the Tsunami disaster that claims millions of lives in 2004.The Rapid rising in temperature of the Tropical world countries and increase in the cases of cancer patients among many other unusual happenings over the last eight years. It was in review of the above situation that this research work was conducted and came up with the under listed suggestions/Recommendations: 1. The UN should use its capacity to discourage

  8. Airing It Out.

    ERIC Educational Resources Information Center

    Fitzemeyer, Ted

    2000-01-01

    Discusses how proper maintenance can help schools eliminate sources contributing to poor air quality. Maintaining heating and air conditioning units, investigating bacterial breeding grounds, fixing leaking boilers, and adhering to ventilation codes and standards are discussed. (GR)

  9. Hazardous Air Pollutants

    MedlinePlus

    ... menu Learn the Issues Air Chemicals and Toxics Climate Change Emergencies Greener Living Health and Safety Land and Cleanup Pesticides Waste Water Science & Technology Air Climate Change Ecosystems Health Land, Waste and Cleanup Pesticides Substances ...

  10. Bad Air Day

    MedlinePlus

    ... children living near busy roadways—surrounded by particulate air pollution—are more likely to develop asthma and other ... found that genes may affect your response to air pollution. At least one gene seems to protect against ...

  11. Transforming air quality management

    SciTech Connect

    Janet McCabe

    2005-04-01

    Earlier this year, the Clean Air Act Advisory Committee submitted to EPA 38 recommendations intended to improve air quality management in the United States. This article summarizes the evaluation process leading up to the Committee's recommendations. 3 refs., 2 figs.

  12. Indoor Air Pollution

    MedlinePlus

    We usually think of air pollution as being outdoors, but the air in your house or office could also be polluted. Sources of indoor pollution include Mold and pollen Tobacco smoke Household products ...

  13. Controlling Indoor Air Pollution.

    ERIC Educational Resources Information Center

    Nero, Anthony V, Jr.

    1988-01-01

    Discusses the health risks posed by indoor air pollutants, such as airborne combustion products, toxic chemicals, and radioactivity. Questions as to how indoor air might be regulated. Calls for new approaches to environmental protection. (TW)

  14. Nuclear air cleaning

    SciTech Connect

    Bellamy, R.R.

    1994-12-31

    This report briefly describes the history of the use of high- efficiency particulate air filters for air cleaning at nuclear installations in the United States and discusses future uses of such filters.

  15. Experimental Studies on High Speed Air Intakes

    NASA Astrophysics Data System (ADS)

    Panigrahy, Amit Kumar; Muruganandam, T. M.

    All high speed air breathing engines require an inlet to decelerate air from free stream velocity to a lower velocity conducive to combustion. The inlet is designed to capture and deliver the required mass flow to combustion chamber with minimum pressure loss, along with minimum flow distortion. Inlet buzz can occur due to several reasons, such as large internal area contraction ratio, serious shock-boundary layer interactions, and high back pressure. Inlet buzz is detrimental to thrust and can even cause structural damage. Thus a detailed back pressure and over contraction based study of inlet behavior is needed.

  16. Compliant layer chucking surface

    SciTech Connect

    Blaedel, Kenneth L.; Spence, Paul A.; Thompson, Samuel L.

    2004-12-28

    A method and apparatus are described wherein a thin layer of complaint material is deposited on the surface of a chuck to mitigate the deformation that an entrapped particle might cause in the part, such as a mask or a wafer, that is clamped to the chuck. The harder particle will embed into the softer layer as the clamping pressure is applied. The material composing the thin layer could be a metal or a polymer for vacuum or electrostatic chucks. It may be deposited in various patterns to affect an interrupted surface, such as that of a "pin" chuck, thereby reducing the probability of entrapping a particle.

  17. Multi-layer coatings

    DOEpatents

    Maghsoodi, Sina; Brophy, Brenor L.; Abrams, Ze'ev R.; Gonsalves, Peter R.

    2016-06-28

    Disclosed herein are coating materials and methods for applying a top-layer coating that is durable, abrasion resistant, highly transparent, hydrophobic, low-friction, moisture-sealing, anti-soiling, and self-cleaning to an existing conventional high temperature anti-reflective coating. The top coat imparts superior durability performance and new properties to the under-laying conventional high temperature anti-reflective coating without reducing the anti-reflectiveness of the coating. Methods and data for optimizing the relative thickness of the under-layer high temperature anti-reflective coating and the top-layer thickness for optimizing optical performance are also disclosed.

  18. The Application of Layer Theory to Design: The Control Layer

    ERIC Educational Resources Information Center

    Gibbons, Andrew S.; Langton, Matthew B.

    2016-01-01

    A theory of design layers proposed by Gibbons ("An Architectural Approach to Instructional Design." Routledge, New York, 2014) asserts that each layer of an instructional design is related to a body of theory closely associated with the concerns of that particular layer. This study focuses on one layer, the control layer, examining…

  19. Possible linkages between Saharan dust and tropical cyclone rain band invigoration in the eastern Atlantic during NAMMA-06

    NASA Astrophysics Data System (ADS)

    Jenkins, Gregory S.; Pratt, Aaron S.; Heymsfield, Andrew

    2008-04-01

    The Saharan Air Layer (SAL) is a dominant feature that influences the large-scale environment from West Africa to the western tropical North Atlantic. While the SAL can create hostile thermodynamic and kinematic environmental conditions for tropical cyclogenesis, it also provides an infusion of cloud condensation and ice nuclei which can potentially invigorate convection. Here we show that these mechanisms may have been involved with the development of Tropical Storm (TS) Debby and Tropical Depression (TD) 8 (later Hurricane Helene) in 2006. Satellite imagery and rawinsondes indicate SAL outbreaks just prior to the emergence of these disturbances over the extreme Eastern tropical Atlantic Ocean. Here we examine the invigoration of convective bands associated with TS Debby and TD-8 based on satellite and direct aircraft measurement. In-situ aircraft measurements show enhanced cloud water content, cloud and precipitation sized particles, lightning and a 26 ms-1 updraft just south of the SAL with TD-8.

  20. Indoor Air Quality Manual.

    ERIC Educational Resources Information Center

    Baldwin Union Free School District, NY.

    This manual identifies ways to improve a school's indoor air quality (IAQ) and discusses practical actions that can be carried out by school staff in managing air quality. The manual includes discussions of the many sources contributing to school indoor air pollution and the preventive planning for each including renovation and repair work,…

  1. Into Thin Air.

    ERIC Educational Resources Information Center

    Kennedy, Mike

    2001-01-01

    Shows how schools are working to avoid the types of equipment, supplies, and maintenance practices that harm indoor air quality. Simple steps to maintaining a cleaner indoor air environment are highlighted as are steps to reducing the problem air quality and the occurrence of asthma. (GR)

  2. Indoor Air Pollution

    MedlinePlus

    We usually think of air pollution as being outdoors, but the air in your house or office could also be polluted. Sources of indoor pollution ... is known as sick building syndrome. Usually indoor air quality problems only cause discomfort. Most people feel ...

  3. Air Travel Health Tips

    MedlinePlus

    MENU Return to Web version Air Travel Health Tips Air Travel Health Tips How can I improve plane travel? Most people don't have any problems when ... and dosages of all of your medicines. The air in airplanes is dry, so drink nonalcoholic, decaffeinated ...

  4. Air Sensor Guidebook

    EPA Science Inventory

    This Air Sensor Guidebook has been developed by the U.S. EPA to assist those interested in potentially using lower cost air quality sensor technologies for air quality measurements. Its development was in direct response to a request for such a document following a recent scienti...

  5. Air Pollution Training Programs.

    ERIC Educational Resources Information Center

    Public Health Service (DHEW), Rockville, MD.

    This catalog lists the universities, both supported and not supported by the Division of Air Pollution, which offer graduate programs in the field of air pollution. The catalog briefly describes the programs and their entrance requirements, the requirements, qualifications and terms of special fellowships offered by the Division of Air Pollution.…

  6. Modelling Hot Air Balloons.

    ERIC Educational Resources Information Center

    Brimicombe, M. W.

    1991-01-01

    A macroscopic way of modeling hot air balloons using a Newtonian approach is presented. Misleading examples using a car tire and the concept of hot air rising are discussed. Pressure gradient changes in the atmosphere are used to explain how hot air balloons work. (KR)

  7. Terby's Layered Rocks

    NASA Technical Reports Server (NTRS)

    2004-01-01

    14 March 2004 Layered rock outcrops are common all across Mars, and the Mars rover, Opportunity, has recently investigated some layered rocks in Meridiani Planum. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary rocks in northern Terby Crater, located just north of the giant Hellas Basin near 27.5oS, 285.8oW. Hundreds of layers are exposed in a deposit several kilometers thick within Terby. A history of events that shaped the northern Hellas region is recorded in these rocks, just waiting for a person or robot to investigate. The picture covers an area 3 km (1.9 mi) across. Sunlight illuminates the scene from the left.

  8. Atmospheric Soundings from AIRS/AMSU/HSB

    NASA Technical Reports Server (NTRS)

    Susskind, Joel; Atlas, Robert

    2004-01-01

    AIRS was launched on EOS Aqua on May 4, 2002, together with AMSU A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. The primary products of AIRS/AMSU/HSB are twice daily global fields of atmospheric temperature-humidity profiles, ozone profiles, sea/land surface skin temperature, and cloud related parameters including OLR. The sounding goals of AIRS are to produce 1 km tropospheric layer mean temperatures with an rms error of lK, and 1 km tropospheric layer precipitable water with an rms error of 20%, in cases with up to 80% effective cloud cover. Pre-launch simulation studies indicated that these results should be achievable. Minor modifications have been made to the pre-launch retrieval algorithm as alluded to in this paper. Sample fields of parameters retrieved from AIRS/AMSU/HSB data are presented and temperature profiles are validated as a function of retrieved effective fractional cloud cover. As in simulation, the degradation of retrieval accuracy with increasing cloud cover is small. Select fields are also compared to those contained in the ECMWF analysis, done without the benefit of AIRS data, to demonstrate information that AIRS can add to that already contained in the ECMWF analysis. Assimilation of AIRS temperature soundings in up to 80% cloud cover for the month of January 2003 into the GSFC FVSSI data assimilation system resulted in improved 5 day forecasts globally, both with regard to anomaly correlation coefficients and the prediction of location and intensity of cyclones.

  9. Structure and Growth of the Marine Boundary Layer

    NASA Technical Reports Server (NTRS)

    Mccumber, M.

    1984-01-01

    LANDSAT visible imagery and a one-dimensional Lagrangian boundary layer model were used to hypothesize the nature and the development of the marine boundary layer during a winter episode of strong seaward cold air advection. Over-water heating and moistening of the cold, dry continental air is estimable from linear relations involving horizontal gradients of the near-surface air temperature and humidity. A line of enhanced convection paralleling the Atlantic U.S. coast from south of New York Bay to the vicinity of Virginia Beach, VA was attributed to stronger convergence at low levels. This feature was characterized as a mesoscale front. With the assistance of a three-dimensional mesoscale boundary layer model, initialized with data obtained from the MASEX, the marine boundary layer can be mapped over the entire Atlantic coastal domain and the evolution of the boundary layer can be studied as a function of different characteristics of important surface level forcings. The effects on boundary layer growth due to the magnitude and pattern of sea surface temperature, to the shape of the coastline, and to atmospheric conditions, such as the orientation of the prevailing wind are examined.

  10. Structured luminescence conversion layer

    DOEpatents

    Berben, Dirk; Antoniadis, Homer; Jermann, Frank; Krummacher, Benjamin Claus; Von Malm, Norwin; Zachau, Martin

    2012-12-11

    An apparatus device such as a light source is disclosed which has an OLED device and a structured luminescence conversion layer deposited on the substrate or transparent electrode of said OLED device and on the exterior of said OLED device. The structured luminescence conversion layer contains regions such as color-changing and non-color-changing regions with particular shapes arranged in a particular pattern.

  11. New challenges threatening the ozone layer

    NASA Astrophysics Data System (ADS)

    Abubakar, Babagana

    Since the beginning of the 1990's when the importation of fairly used Refrigerators, Airconditioners and propellants that can easily go broken containing chlorofluorocarbon substances that is capable of destroying the Ozone layer started in commercial quantity in Africa, the African refuse mountains began metamorphosing into mountains of dumped broken Refrigerators, Air-conditioners and Propellants which are collectively becoming a threat to the Ozone layer, because of the continuous discharging of the Chlorofluorocarbon gases by the refuse in to the atmosphere in each passing second.. Nobody can actually quantify the numbers of Refrigerators, Air-conditioners and Propellants imported and disposed in Africa over the last fifteen years, but the facts still remains that the numbers of metamorphosing mountains keeps on increasing in both size and numbers in each passing day. They have even become sources of raw materials for the local blacksmiths, children and refrigerators repairers who use parts of the dumped refrigerators, Air-conditioners and Propellants for their constructions, toys and repairs respectively. This explains the reason why despite the global efforts toward protecting the Ozone layer by the United Nations (UN), governments, International Organizations and climatologist among many others, but yet the hole in the Ozone layer keeps on expanding and the global temperature keeps on rising which resulted in the unusual phenomenon like the hurricanes "Katrina" and "Rita" the unusual floods in China, Thailand, Mozambique and to some extent even the Tsunami disaster that claims millions of lives in 2004.The Rapid rising in temperature of the Tropical world countries and increase in the cases of cancer patients among many other unusual happenings over the last eight years. It was in review of the above situation that this research work was conducted and came up with the under listed suggestions/Recommendations: 1. The UN should use its capacity to discourage

  12. Air Conditioning Does Reduce Air Pollution Indoors

    ERIC Educational Resources Information Center

    Healy, Bud

    1970-01-01

    Report of the winter meeting of the American Society of Heating, Refrigerating and Air-Conditioning Engineers. Subjects covered are--(1) title subject, (2) predictions for the human habitat in 1994, (3) fans, and (4) fire safety in buildings. (JW)

  13. Air Sparging Decision Tool

    1996-06-10

    The Air Sparging Decision Tool is a computer decision aid to help environmental managers and field practitioners in evaluating the applicability of air sparging to a wide range of sites and for refining the operation of air sparging systems. The program provides tools for the practitioner to develop the conceptual design for an air sparging system suitable for the identified site. The Tool provides a model of the decision making process, not a detailed designmore » of air sparging systems. The Tool will quickly and cost effectively assist the practitioner in screening for applicability of the technology at a proposed site.« less

  14. Evaluation of Filters for Removal of Bacteriophages from Air1

    PubMed Central

    Washam, C. J.; Black, C. H.; Sandine, W. E.; Elliker, P. R.

    1966-01-01

    Glass wool, nonabsorbent cotton, fiberglass filter medium, and a commercial absolute filter were tested for effectiveness in removing aerosolized bacterial viruses under low flow rate (1 ft3/min) and high flow rate (10 to 25 ft3/min) air-flow conditions. Special equipment was designed for measurement of filter efficiencies under the two air-flow conditions. Under low air-flow rate test conditions, glass wool was only 98.543 to 99.83% efficient, whereas cotton (five layers), fiberglass medium (three layers), and the commercial absolute filter were at least 99.900, 99.999, and 99.999 efficient, respectively. Glass wool and cotton were not used under higher air-flow conditions because they were difficult to assemble in leak-tight filters. The commercial absolute filter and fiberglass medium (three layers) were at least 99.990 and 99.999% efficient, respectively, under the higher air flow conditions. A stainless-steel filter of simple design and fitted with three layers of fiberglass medium was found to be greater than 99.999% efficient in removing high concentrations (20,000 to 70,000 plaque-forming units per cubic foot) of aerosolized bacteriophages from air moving at a low flow rate (1 ft3/min). Use of this filter on pressure-vacuum tanks in the fermentation industry is suggested. Several other uses of such a filter are proposed. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:5927020

  15. 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.

  16. Hepa room air purifier

    SciTech Connect

    Davis, G.B.

    1986-12-16

    This patent describes a portable air purification apparatus comprising a housing including a base portion and cover means, the base portion including an air deflection means and a plate means mounted in spaced relationship to the air deflection means so as to create a substantially continuous air exhaust opening therebetween. A centrifugal fan means is disposed between the plate means and the air deflection means and is mounted so as to direct air radially outwardly therefrom through the air exhaust opening, at least one opening through the plate means to permit air flow therethrough to the centrifugal fan means. The motor means carried by the base portion and extends upwardly with respect to the opening in the plate means, the motor means having drive shaft means for driving the centrifugal fan means. An air filter means is mounted between the base portion and the cover means so that air is drawn therethrough toward the centrifugal fan means, and a means for secures the cover means relative to the base means to thereby retain the air filter means therebetween.

  17. Air Conditioner/Dehumidifier

    NASA Technical Reports Server (NTRS)

    1986-01-01

    An ordinary air conditioner in a very humid environment must overcool the room air, then reheat it. Mr. Dinh, a former STAC associate, devised a heat pipe based humidifier under a NASA Contract. The system used heat pipes to precool the air; the air conditioner's cooling coil removes heat and humidity, then the heat pipes restore the overcooled air to a comfortable temperature. The heat pipes use no energy, and typical savings are from 15-20%. The Dinh Company also manufactures a "Z" coil, a retrofit cooling coil which may be installed on an existing heater/air conditioner. It will also provide free hot water. The company has also developed a photovoltaic air conditioner and solar powered water pump.

  18. Direct Simulation of Shock Layer Plasmas

    SciTech Connect

    Farbar, E. D.; Boyd, I. D.

    2011-05-20

    Approximate models of the electric field used with the DSMC method all impose quasi-neutrality everywhere in the shock layer plasma. The shortcomings of these models are examined in this study by simulating a weak shock layer plasma with a coupled DSMC-Particle-In-Cell (PIC) method. The stagnation streamline of an axisymmetric shock layer is simulated for entry velocities in air that correspond to both lunar and Mars return trajectories. The atmospheric densities, particle diameters and chemical reaction rates are varied from the actual values to make the computations tractable while retaining the mean free path of air at 85 km altitude. In contrast to DSMC flow field predictions, regions of non-neutrality are predicted by the DSMC-PIC method, and the electrons are predicted to be isothermal. Perhaps the most important result of this study is that the DSMC-PIC results at both reentry energies yield a 14% increase in heat flux to the vehicle surface relative to the DSMC results. Rather unintuitively, this is mostly due to an increase in ion flux to the surface, rather than the potential energy gained by each ion as it traverses the plasma sheath. In this study, an approximate electric field model is presented, with the goal of accounting for this heat flux augmentation without the need for a computationally expensive DSMC-PIC calculation of the entire flow-field. Convective heat flux results obtained with new electric field model are compared to results from the rigorous DSMC-PIC calculations.

  19. LiNiFe-based layered structure oxide and composite for advanced single layer fuel cells

    NASA Astrophysics Data System (ADS)

    Zhu, Bin; Fan, Liangdong; Deng, Hui; He, Yunjune; Afzal, Muhammad; Dong, Wenjing; Yaqub, Azra; Janjua, Naveed K.

    2016-06-01

    A layered structure metal oxide, LiNi0.1Fe0.90O2-δ (LNF), is explored for the advanced single layer fuel cells (SLFCs). The temperature dependent impedance profiles and concentration cells (hydrogen concentration, oxygen concentration, and H2/air atmospheres) tests prove LNF to be an intrinsically electronic conductor in air while mixed electronic and proton conductor in H2/air environment. SLFCs constructed by pure LNF materials show significant short circuiting reflected by a low device OCV and power output (175 mW cm-2 at 500 °C) due to high intrinsic electronic conduction. The power output is improved up to 640 and 760 mW cm-2, respectively at 500 and 550 °C by compositing LNF with ion conducting material, e.g., samarium doped ceria (SDC), to balance the electronic and ionic conductivity; both reached at 0.1 S cm-1 level. Such an SLFC gives super-performance and simplicity over the conventional 3-layer (anode, electrolyte and cathode) FCs, suggesting strong scientific and commercial impacts.

  20. BamI, KpnI, and SalI restriction enzyme maps of the DNAs of herpes simplex virus strains Justin and F: occurrence of heterogeneities in defined regions of the viral DNA.

    PubMed Central

    Locker, H; Frenkel, N

    1979-01-01

    We present the locations of the cleavage sites for the BamI, KpnI, and SalI restriction endonucleases within the DNA molecules of herpes simplex virus type 1 (HSV-1) strains Justin and F. These restriction enzymes cleave the HSV-1 DNA at many sites, producing relatively small fragments which should prove useful in future studies of HSV-1 gene structure and function. The mapping data revealed the occurrence of heterogeneity within three regions of the viral genome including (i) the region spanning map coordinates 0.74--0.76, (ii) the ends of the large (L) DNA component, and (iii) the junction between the large (L) and the small (S) components. The heterogeneity in the ends of L and the S-L junctions of HSV-1 (Justin) and HSV-1 (F) DNAs was grossly similar to that previously reported to occur in the ends of L and the S-L junctions of the HSV-1 (KOS) DNA (M. J. Wagner and W. C. Summers, J. Virol. 27:374--387, 1978). Thus, cleavage of these regions with restriction endonucleases yielded sets of minor fragments differing in size by constant increments. However, the various strains of HSV-1 differed with respect to the numbers, size increments, and relative molarities of the various minor fragments, suggesting that the parameters of the heterogeneity are inherited in the structural makeup of the HSV-1 genome. The strain dependence of the pattern of heterogeneity can be most easily explained in terms of variable sizes of the terminally reiterated a sequence, contained in the DNA molecules of these three strains of HSV-1. Images PMID:228068

  1. Tests on Double Layer Metalization

    NASA Technical Reports Server (NTRS)

    Woo, D. S.

    1983-01-01

    28 page report describes experiments in fabrication of integrated circuits with double-layer metalization. Double-layer metalization requires much less silicon "real estate" and allows more flexibility in placement of circuit elements than does single-layer metalization.

  2. Health Effects of Air Pollution

    MedlinePlus

    ... Health effects of air pollution Health effects of air pollution Breathing air that is not clean can hurt ... important to know about the health effects that air pollution can have on you and others. Once you ...

  3. Modulational Instability in a Layered Kerr Medium: Theory and Experiment

    NASA Astrophysics Data System (ADS)

    Centurion, Martin; Porter, Mason A.; Pu, Ye; Kevrekidis, P. G.; Frantzeskakis, D. J.; Psaltis, Demetri

    2006-12-01

    We present the first experimental investigation of modulational instability in a layered Kerr medium. The particularly interesting and appealing feature of our configuration, consisting of alternating glass-air layers, is the piecewise-constant nature of the material properties, which allows a theoretical linear stability analysis leading to a Kronig-Penney equation whose forbidden bands correspond to the modulationally unstable regimes. We find very good quantitative agreement between theoretical, numerical, and experimental diagnostics of the modulational instability. Because of the periodicity in the evolution variable arising from the layered medium, there are multiple instability regions rather than just one as in a uniform medium.

  4. EDITORIAL: Atomic layer deposition Atomic layer deposition

    NASA Astrophysics Data System (ADS)

    Godlewski, Marek

    2012-07-01

    The growth method of atomic layer deposition (ALD) was introduced in Finland by Suntola under the name of atomic layer epitaxy (ALE). The method was originally used for deposition of thin films of sulphides (ZnS, CaS, SrS) activated with manganese or rare-earth ions. Such films were grown for applications in thin-film electroluminescence (TFEL) displays. The ALE mode of growth was also tested in the case of molecular beam epitaxy. Films grown by ALD are commonly polycrystalline or even amorphous. Thus, the name ALE has been replaced by ALD. In the 80s ALD was developed mostly in Finland and neighboring Baltic countries. Deposition of a range of different materials was demonstrated at that time, including II-VI semiconductors (e.g. CdTe, CdS) and III-V (e.g. GaAs, GaN), with possible applications in e.g. photovoltaics. The number of publications on ALD was slowly increasing, approaching about 100 each year. A real boom in interest came with the development of deposition methods of thin films of high-k dielectrics. This research was motivated by a high leakage current in field-effect transistors with SiO2-based gate dielectrics. In 2007 Intel introduced a new generation of integrated circuits (ICs) with thin films of HfO2 used as gate isolating layers. In these and subsequent ICs, films of HfO2 are deposited by the ALD method. This is due to their unique properties. The introduction of ALD to the electronics industry led to a booming interest in the ALD growth method, with the number of publications increasing rapidly to well above 1000 each year. A number of new applications were proposed, as reflected in this special issue of Semiconductor Science and Technology. The included articles cover a wide range of possible applications—in microelectronics, transparent electronics, optoelectronics, photovoltaics and spintronics. Research papers and reviews on the basics of ALD growth are also included, reflecting a growing interest in precursor chemistry and growth

  5. Biocorrosion behavior of biodegradable nanocomposite fibers coated layer-by-layer on AM50 magnesium implant.

    PubMed

    Abdal-Hay, Abdalla; Hasan, Anwarul; Kim, Yu-Kyoung; Yu-Kyoung; Lee, Min-Ho; Hamdy, Abdel Salam; Khalil, Khalil Abdelrazek

    2016-01-01

    This article demonstrates the use of hybrid nanofibers to improve the biodegradation rate and biocompatibility of AM50 magnesium alloy. Biodegradable hybrid membrane fiber layers containing nano-hydroxyapatite (nHA) particles and poly(lactide)(PLA) nanofibers were coated layer-by-layer (LbL) on AM50 coupons using a facile single-step air jet spinning (AJS) approach. The corrosion performance of coated and uncoated coupon samples was investigated by means of electrochemical measurements. The results showed that the AJS 3D membrane fiber layers, particularly the hybrid membrane layers containing a small amount of nHA (3 wt.%), induce a higher biocorrosion resistance and effectively decrease the initial degradation rate compared with the neat AM50 coupon samples. The adhesion strength improved highly due to the presence of nHA particles in the AJS layer. Furthermore, the long biodegradation rates of AM50 alloy in Hank's balanced salt solution (HBSS) were significantly controlled by the AJS-coatings. The results showed a higher cytocompatibility for AJS-coatings compared to that for neat Mg alloys. The nanostructured nHA embedded hybrid PLA nanofiber coating can therefore be a suitable coating material for Mg alloy as a potential material for biodegradable metallic orthopedic implants. PMID:26478426

  6. A review on air cathodes for zinc-air fuel cells

    NASA Astrophysics Data System (ADS)

    Neburchilov, Vladimir; Wang, Haijiang; Martin, Jonathan J.; Qu, Wei

    This paper reviews the compositions, design and methods of fabrication of air cathodes for alkali zinc-air fuel cells (ZAFCs), one of the few successfully commercialized fuel cells. The more promising compositions for air cathodes are based on individual oxides, or mixtures of such, with a spinel, perovskite, or pyrochlore structure: MnO 2, Ag, Co 3O 4, La 2O 3, LaNiO 3, NiCo 2O 4, LaMnO 3, LaNiO 3, etc. These compositions provide the optimal balance of ORR activity and chemical stability in an alkali electrolyte. The sol-gel and reverse micelle methods supply the most uniform distribution of the catalyst on carbon and the highest catalyst BET surface area. It is shown that the design of the air cathode, including types of carbon black, binding agents, current collectors, Teflon membranes, thermal treatment of the GDL, and catalyst layers, has a strong effect on performance.

  7. Layered electrode for electrochemical cells

    DOEpatents

    Swathirajan, Swathy; Mikhail, Youssef M.

    2001-01-01

    There is provided an electrode structure comprising a current collector sheet and first and second layers of electrode material. Together, the layers improve catalyst utilization and water management.

  8. Global Warming and Air Quality in China

    NASA Astrophysics Data System (ADS)

    Liu, S. C.

    2014-12-01

    The atmospheric lapse rate has been observed to decrease as a result of global warming. Reduced lapse rate is a result of a robust water vapor/lapse rate climate feedback simulated in coupled ocean-atmosphere models. The reduced lapse rate makes the atmosphere more stable, and in turn the more stable atmosphere can affect air quality in many aspects, most of them detrimental to the air quality. The largest effect of an increased vertical stability is an increased trapping of air pollutants in the boundary layer. A more stable atmosphere also makes it less likely to precipitate, especially for light and moderate precipitation that requires an unstable large-scale environment. Thus there is less scavenging of air pollutants by precipitation. Furthermore less precipitation implies less cloud cover or more clear days which can result in more nighttime inversions, again trapping more pollutants in the surface layer. Significant increase in clear days has been observed in China in the last 50 years, this can be a major contributor to more and worse fog/haze events in recent decades.

  9. Marine antifouling from thin air.

    PubMed

    Arnott, Jaimys; Wu, Alex H F; Vucko, Matthew J; Lamb, Robert N

    2014-10-01

    The dynamic relationship between the settlement behaviour of marine biota (cells, spores, larvae) and the longevity of an entrapped air layer (plastron) on submersed superhydrophobic surfaces was systematically investigated. Plastron lifetime decreased with increasing hydrophobic polymer loadings, and was correlated with the settlement rate of a range of fouling species of varying length scale, motility and hydrophobic/hydrophilic surface preference. The results show that the level of fouling on immersed superhydrophobic surfaces was greater when plastron lifetimes were minimal, regardless of the length scale, motility and the surface preference of the organisms. This is the first direct demonstration of the broad-spectrum attachment-inhibiting properties of a plastron on an immersed superhydrophobic surface. PMID:25329518

  10. Ridged Layer Outcrop

    NASA Technical Reports Server (NTRS)

    2004-01-01

    15 August 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a strange ridged pattern developed in an eroding layer of material on the floor of a Labyrinthus Noctis depression in the Valles Marineris system. The ridges bear some resemblance to ripple-like dunes seen elsewhere on Mars, but they are linked to the erosion of a specific layer of material--i.e., something in the rock record of Mars. Similar ridged textures are found in eroded dark-toned mantling layers in regions as far away as northern Sinus Meridiani and Mawrth Vallis. The explanation for these landforms is as elusive as this image is evocative. The image is located near 8.2oS, 93.6oW, and covers an area 3 km (1.9 mi) across. The scene is illuminated by sunlight from the upper left.

  11. South Polar Layers

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-516, 17 October 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows eroded, stair-stepped layers in the south polar region of Mars. These layers have been considered, for the past three decades, to consist of a mixture of dust and ice. The Mars Polar Lander (MPL) mission was designed to test this hypothesis. However, sadly, MPL was lost during descent in December 1999. This exposure of south polar layered material is located near 86.3oS, 187.7oW. The image covers an area 3 km (1.9 mi) wide and is illuminated by sunlight from the upper left.

  12. Layers in Terby Crater

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-407, 30 June 2003

    Whether on Earth or Mars, sedimentary rocks provide a record of past environments. Of course, it is difficult to read that record without being able to visit the site. However, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) has revealed hundreds of locales on Mars at which sedimentary rocks are exposed at the surface. Terby Crater exhibits hundreds of layers of similar thickness and physical properties--some have speculated these may be the record of an ancient lake or sea. This MOC image shows some of the layer outcrops in Terby Crater. Fans of debris have eroded from the steep, layered slopes in some places. This picture covers an area 3 km (1.9 mi) wide near 27.5oS, 285.7oW. The image is illuminated from the upper left and was obtained in June 2003.

  13. Craters and Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    11 March 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows some typical relations between impact craters and light-toned, layered rock on Mars. The larger circular feature at the north (top) end of the image marks the location of a filled, buried crater on intermountain terrain north of Hellas Planitia. The larger crater at the southeast (lower right) corner formed by meteor impact into the layered material in which the buried crater is encased. The layered rock, in this case, has a light tone similar to the sedimentary rocks being explored by the Mars Exploration Rover, Opportunity, thousands of kilometers away in Sinus Meridiani.

    Location near: 24.9oS, 299.3oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  14. East Candor Layers

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-507, 8 October 2003

    The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) experiment was designed to study the geology and geomorphology of Mars by providing images comparable in resolution to the aerial photographs used by terrestrial geologists in conducting their field work. For over six years, the MOC narrow angle camera has been returning pictures that underscore, time and again, the layered nature of the upper martian crust. It is from layered rock that geologists will one day be able to decipher the history of the red planet. This example of layered rock exposures occurs in eastern Candor Chasma, one of the troughs of the Valles Marineris system. The picture is located near 8.0oS, 67.0oW, and covers an area 3 km (1.9 mi) wide. The image is illuminated by sunlight from the lower left.

  15. Boundary layer simulator improvement

    NASA Technical Reports Server (NTRS)

    Praharaj, Sarat C.; Schmitz, Craig P.; Nouri, Joseph A.

    1989-01-01

    Boundary Layer Integral Matrix Procedure (BLIMPJ) has been identified by the propulsion community as the rigorous boundary layer program in connection with the existing JANNAF reference programs. The improvements made to BLIMPJ and described herein have potential applications in the design of the future Orbit Transfer Vehicle engines. The turbulence model is validated to include the effects of wall roughness and a way is devised to treat multiple smooth-rough surfaces. A prediction of relaminarization regions is examined as is the combined effects of wall cooling and surface roughness on relaminarization. A turbulence model to represent the effects of constant condensed phase loading is given. A procedure is described for thrust decrement calculation in thick boundary layers by coupling the T-D Kinetics Program and BLIMPJ and a way is provided for thrust loss optimization. Potential experimental studies in rocket nozzles are identified along with the required instrumentation to provide accurate measurements in support of the presented new analytical models.

  16. Layered Systems Engineering Engines

    NASA Technical Reports Server (NTRS)

    Breidenthal, Julian C.; Overman, Marvin J.

    2009-01-01

    A notation is described for depicting the relationships between multiple, contemporaneous systems engineering efforts undertaken within a multi-layer system-of-systems hierarchy. We combined the concepts of remoteness of activity from the end customer, depiction of activity on a timeline, and data flow to create a new kind of diagram which we call a "Layered Vee Diagram." This notation is an advance over previous notations because it is able to be simultaneously precise about activity, level of granularity, product exchanges, and timing; these advances provide systems engineering managers a significantly improved ability to express and understand the relationships between many systems engineering efforts. Using the new notation, we obtain a key insight into the relationship between project duration and the strategy selected for chaining the systems engineering effort between layers, as well as insights into the costs, opportunities, and risks associated with alternate chaining strategies.

  17. Shock layer radiance effects on endoatmospheric interceptor seeker performance

    NASA Astrophysics Data System (ADS)

    Trolier, J.; Hudson, D.; Carlson, D.; Krawczyk, W.

    1992-05-01

    A method is described in detail to allow prediction of infrared radiance from shock layers surrounding high altitude hypersonic endoatmospheric interceptors. Flowfield properties calculated with the EXTC code for a representative endoatmospheric interceptor forebody are shown, including thermal and chemical nonequilibrium effects for both clean air and atmospheric trace species. The SIRRM-II radiative transport code was used with a modified version of the NORSE infrared radiance database to predict radiance and transmission through the shock layer. A simple sensor model, including spectral target signatures, window thermal emission noise, and shock layer radiance is employed to illustrate the importance of the shock layer radiance effects. Shock layer radiance is found to increase with decreasing altitude, with significant broadening of spectral emission bands at lower altitudes.

  18. Cumulus cloud venting of mixed layer ozone

    NASA Technical Reports Server (NTRS)

    Ching, J. K. S.; Shipley, S. T.; Browell, E. V.; Brewer, D. A.

    1985-01-01

    Observations are presented which substantiate the hypothesis that significant vertical exchange of ozone and aerosols occurs between the mixed layer and the free troposphere during cumulus cloud convective activity. The experiments utilized the airborne Ultra-Violet Differential Absorption Lidar (UV-DIAL) system. This system provides simultaneous range resolved ozone concentration and aerosol backscatter profiles with high spatial resolution. Evening transects were obtained in the downwind area where the air mass had been advected. Space-height analyses for the evening flight show the cloud debris as patterns of ozone typically in excess of the ambient free tropospheric background. This ozone excess was approximately the value of the concentration difference between the mixed layer and free troposphere determined from independent vertical soundings made by another aircraft in the afternoon.

  19. Sedimentary Rock Layers

    NASA Technical Reports Server (NTRS)

    2004-01-01

    27 January 2004 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layers of sedimentary rock in a crater in western Arabia Terra. Layered rock records the history of a place, but an orbiter image alone cannot tell the entire story. These materials record some past episodes of deposition of fine-grained material in an impact crater that is much larger than the image shown here. The picture is located near 3.4oN, 358.7oW, and covers an area 3 km (1.9 mi.) wide. Sunlight illuminates the scene from the lower left.

  20. Layered semiconductor neutron detectors

    DOEpatents

    Mao, Samuel S; Perry, Dale L

    2013-12-10

    Room temperature operating solid state hand held neutron detectors integrate one or more relatively thin layers of a high neutron interaction cross-section element or materials with semiconductor detectors. The high neutron interaction cross-section element (e.g., Gd, B or Li) or materials comprising at least one high neutron interaction cross-section element can be in the form of unstructured layers or micro- or nano-structured arrays. Such architecture provides high efficiency neutron detector devices by capturing substantially more carriers produced from high energy .alpha.-particles or .gamma.-photons generated by neutron interaction.

  1. Hyperspectral air-to-air seeker

    NASA Astrophysics Data System (ADS)

    Gat, Nahum; Barhen, Jacob; Gulati, Sandeep; Steiner, Todd D.

    1994-07-01

    Synthetic hyperspectral signatures representing an airborne target engine radiation, a decoy flare, and the engine plume radiation are used to demonstrate computational techniques for the discrimination between such objects. Excellent discrimination is achieved for a `single look' at SNR of -10 dB. Since the atmospheric transmittance perturbs the signature of all objects in an identical fashion, the transmittance is equivalent to a modulation of the target radiance (in the spectral domain). The proper spectral signal decomposition may, therefore, recover the original unperturbed signature accurately enough to allow discrimination. The algorithms described here, and in two accompanying papers, have been tested over the spectral range that includes the VNIR and MWIR and are most appropriate for an intelligent, autonomous, air-to-air or surface-to-air guided munitions. With additional enhancements, the techniques apply to ground targets and other dual-use applications.

  2. High Lapse Rates in AIRS Retrieved Temperatures in Cold Air Outbreaks

    NASA Technical Reports Server (NTRS)

    Fetzer, Eric J.; Kahn, Brian; Olsen, Edward T.; Fishbein, Evan

    2004-01-01

    The Atmospheric Infrared Sounder (AIRS) experiment, on NASA's Aqua spacecraft, uses a combination of infrared and microwave observations to retrieve cloud and surface properties, plus temperature and water vapor profiles comparable to radiosondes throughout the troposphere, for cloud cover up to 70%. The high spectral resolution of AIRS provides sensitivity to important information about the near-surface atmosphere and underlying surface. A preliminary analysis of AIRS temperature retrievals taken during January 2003 reveals extensive areas of superadiabatic lapse rates in the lowest kilometer of the atmosphere. These areas are found predominantly east of North America over the Gulf Stream, and, off East Asia over the Kuroshio Current. Accompanying the high lapse rates are low air temperatures, large sea-air temperature differences, and low relative humidities. Imagery from a Visible / Near Infrared instrument on the AIRS experiment shows accompanying clouds. These lines of evidence all point to shallow convection in the bottom layer of a cold air mass overlying warm water, with overturning driven by heat flow from ocean to atmosphere. An examination of operational radiosondes at six coastal stations in Japan shows AIRS to be oversensitive to lower tropospheric lapse rates due to systematically warm near-surface air temperatures. The bias in near-surface air temperature is seen to be independent of sea surface temperature, however. AIRS is therefore sensitive to air-sea temperature difference, but with a warm atmospheric bias. A regression fit to radiosondes is used to correct AIRS near-surface retrieved temperatures, and thereby obtain an estimate of the true atmosphere-ocean thermal contrast in five subtropical regions across the north Pacific. Moving eastward, we show a systematic shift in this air-sea temperature differences toward more isothermal conditions. These results, while preliminary, have implications for our understanding of heat flow from ocean to

  3. Hospital air is sick.

    PubMed

    Brownson, K

    2000-11-01

    Indoor air quality has deteriorated so much since the 1970s oil shortage and subsequent energy-efficient construction of buildings that people are becoming seriously ill by just breathing the indoor air. This is a problem with all industrial buildings and hospital staff are at particular risk. There are various things that hospital managers from different departments can do to make the air safe for staff and patients to breathe. PMID:11185833

  4. Ruthenium / aerogel nanocomposits via Atomic Layer Deposition

    SciTech Connect

    Biener, J; Baumann, T F; Wang, Y; Nelson, E J; Kucheyev, S O; Hamza, A V; Kemell, M; Ritala, M; Leskela, M

    2006-08-28

    We present a general approach to prepare metal/aerogel nanocomposites via template directed atomic layer deposition (ALD). In particular, we used a Ru ALD process consisting of alternating exposures to bis(cyclopentadienyl)ruthenium (RuCp{sub 2}) and air at 350 C to deposit metallic Ru nanoparticles on the internal surfaces of carbon and silica aerogels. The process does not affect the morphology of the aerogel template and offers excellent control over metal loading by simply adjusting the number of ALD cycles. We also discuss the limitations of our ALD approach, and suggest ways to overcome these.

  5. Solar Air Sampler

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Nation's first solar-cell-powered air monitoring station was installed at Liberty State Park, New Jersey. Jointly sponsored by state agencies and the Department of Energy, system includes display which describes its operation to park visitors. Unit samples air every sixth day for a period of 24 hours. Air is forced through a glass filter, then is removed each week for examination by the New Jersey Bureau of Air Pollution. During the day, solar cells provide total power for the sampling equipment. Excess energy is stored in a bank of lead-acid batteries for use when needed.

  6. Personal continuous air monitor

    DOEpatents

    Morgan, Ronald G.; Salazar, Samuel A.

    2000-01-01

    A personal continuous air monitor capable of giving immediate warning of the presence of radioactivity has a filter/detector head to be worn in the breathing zone of a user, containing a filter mounted adjacent to radiation detectors, and a preamplifier. The filter/detector head is connected to a belt pack to be worn at the waist or on the back of a user. The belt pack contains a signal processor, batteries, a multichannel analyzer, a logic circuit, and an alarm. An air pump also is provided in the belt pack for pulling air through the filter/detector head by way of an air tube.

  7. Applications Using AIRS Data

    NASA Astrophysics Data System (ADS)

    Ray, S. E.; Pagano, T. S.; Fetzer, E. J.; Lambrigtsen, B.; Olsen, E. T.; Teixeira, J.; Licata, S. J.; Hall, J. R.; Thompson, C. K.

    2015-12-01

    The Atmospheric Infrared Sounder (AIRS) on NASA's Aqua spacecraft has been returning daily global observations of Earth's atmospheric constituents and properties since 2002. With a 12-year data record and daily, global observations in near real-time, AIRS data can play a role in applications that fall under many of the NASA Applied Sciences focus areas. For vector-borne disease, research is underway using AIRS near surface retrievals to assess outbreak risk, mosquito incubation periods and epidemic potential for dengue fever, malaria, and West Nile virus. For drought applications, AIRS temperature and humidity data are being used in the development of new drought indicators and improvement in the understanding of drought development. For volcanic hazards, new algorithms using AIRS data are in development to improve the reporting of sulfur dioxide concentration, the burden and height of volcanic ash and dust, all of which pose a safety threat to aircraft. In addition, anomaly maps of many of AIRS standard products are being produced to help highlight "hot spots" and illustrate trends. To distribute it's applications imagery, AIRS is leveraging existing NASA data frameworks and organizations to facilitate archiving, distribution and participation in the BEDI. This poster will communicate the status of the applications effort for the AIRS Project and provide examples of new maps designed to best communicate the AIRS data.

  8. Planetary Boundary Layer from AERI and MPL

    SciTech Connect

    Sawyer, Virginia

    2014-02-13

    The distribution and transport of aerosol emitted to the lower troposphere is governed by the height of the planetary boundary layer (PBL), which limits the dilution of pollutants and influences boundary-layer convection. Because radiative heating and cooling of the surface strongly affect the PBL top height, it follows diurnal and seasonal cycles and may vary by hundreds of meters over a 24-hour period. The cap the PBL imposes on low-level aerosol transport makes aerosol concentration an effective proxy for PBL height: the top of the PBL is marked by a rapid transition from polluted, well-mixed boundary-layer air to the cleaner, more stratified free troposphere. Micropulse lidar (MPL) can provide much higher temporal resolution than radiosonde and better vertical resolution than infrared spectrometer (AERI), but PBL heights from all three instruments at the ARM SGP site are compared to one another for validation. If there is agreement among them, the higher-resolution remote sensing-derived PBL heights can accurately fill in the gaps left by the low frequency of radiosonde launches, and thus improve model parameterizations and our understanding of boundary-layer processes.

  9. Boundary Layer Control for Hypersonic Airbreathing Vehicles

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Nowak, Robert J.; Horvath, Thomas J.

    2004-01-01

    Active and passive methods for tripping hypersonic boundary layers have been examined in NASA Langley Research Center wind tunnels using a Hyper-X model. This investigation assessed several concepts for forcing transition, including passive discrete roughness elements and active mass addition (or blowing), in the 20-Inch Mach 6 Air and the 31-Inch Mach 10 Air Tunnels. Heat transfer distributions obtained via phosphor thermography, shock system details, and surface streamline patterns were measured on a 0.333-scale model of the Hyper-X forebody. The comparisons between the active and passive methods for boundary layer control were conducted at test conditions that nearly match the Hyper-X nominal Mach 7 flight test-point of an angle-of-attack of 2-deg and length Reynolds number of 5.6 million. For passive roughness, the primary parametric variation was a range of trip heights within the calculated boundary layer thickness for several trip concepts. The passive roughness study resulted in a swept ramp configuration, scaled to be roughly 0.6 of the calculated boundary layer thickness, being selected for the Mach 7 flight vehicle. For the active blowing study, the manifold pressure was systematically varied (while monitoring the mass flow) for each configuration to determine the jet penetration height, with schlieren, and transition movement, with the phosphor system, for comparison to the passive results. All the blowing concepts tested, which included various rows of sonic orifices (holes), two- and three-dimensional slots, and random porosity, provided transition onset near the trip location with manifold stagnation pressures on the order of 40 times the model surface static pressure, which is adequate to ensure sonic jets. The present results indicate that the jet penetration height for blowing was roughly half the height required with passive roughness elements for an equivalent amount of transition movement.

  10. Dense gas boundary layer experiments: Visualization, pressure measurements, concentration evaluation

    SciTech Connect

    Reichenbach, H.; Neuwald, P.; Kuhl, A.L.

    1992-11-01

    This technical report describes methods that were applied to investigate turbulent boundary layers generated by inviscid, baroclinic effects. The Cranz-Schardin 24-sparks camera was used to visualize the interactions of a planar shock wave with a Freon R12-layer. The shock propagates more slowly in the Freon layer than in air because of its smaller sound speed. This causes the shock front to be curved and to be reflected between the wall and the layer interface. As a consequence of the reflection process, a series of compression and expansion waves radiate from the layer. Large fluctuations in the streamwise velocity and in pressure develop for about 1 ms. These waves strongly perturb the interface shear layer, which rapidly transitions to a turbulent boundary flow. Pressure measurements showed that the fluctuations in the Freon layer reach a peak pressure 4 times higher than in the turbulent boundary flow. To characterize the preshock Freon boundary layer, concentration measurements were performed with a differential interferometry technique. The refraction index of Freon R12 is so high that Mach-Zehnder interferometry was not successful in these experiments. The evaluation of the concentration profile is described here in detail. Method and results of corresponding LDV measurements under the same conditions are presented in a different report, EMI Report T 9/92. The authors plan to continue the dense gas layer investigations with the gas combination helium/Freon.

  11. Scanning Tunneling Microscopy of Layered Materials

    NASA Astrophysics Data System (ADS)

    Qin, Xiaorong

    This dissertation describes studies of the surfaces of layered materials, including graphite intercalation compounds, transition-metal-dichalcogenides, and single layers of MoS_2. with scanning tunneling microscopy (STM). In order to understand how tunneling images reflect the atomic nature of sample surfaces, the electronic and structural properties of intercalated graphite surfaces imaged with STM have been investigated theoretically. The corrugation amplitude (CA) and carbon site asymmetry (CSA) are sensitive to the number of graphite layers covering the first intercalate layer, to the amount and distribution of the charge transferred from intercalate to host and to the surface subband structure. The CA and CSA can be used to map the stage domains across a freshly cleaved surface. The STM images of the surfaces of both donor and acceptor graphite intercalation compounds are discussed. The theory successfully explained the available experimental results, and yielded some predictions which have been verified in recent experiments. A STM system for operation in air was assembled. The crystalline surfaces of graphite and three transition-metal -dichalcogenides (2H-MoS_2, WTe _2 and ReSe_2) have been studied with the STM system. Single layers of MoS_2 can be obtained by the exfoliation of lithium-intercalated MoS_2 powder in water and in several alcohols. In the STM observations, the samples were prepared by depositing either an aqueous or butanol suspension of single-layer MoS_2 on graphite substrates to form restacked films with two monolayers of solvent molecules included between the layers of MoS_2 . The real-space images obtained from the films all showed the existence of an approximate 2 x 1 superstructure on the surfaces, although the 2 x 1 pattern can be modulated by the interface interaction between the MoS_2 layer and the solvent molecules. These results, in conjunction with existing x-ray diffraction and Raman results, imply that the single layers of MoS_2

  12. Possibilities for drag reduction by boundary layer control

    NASA Technical Reports Server (NTRS)

    Naiman, I.

    1946-01-01

    The mechanics of laminar boundary layer transition are reviewed. Drag possibilities for boundary layer control are analyzed using assumed conditions of transition Reynolds number, inlet loss, number of slots, blower efficiency, and duct losses. Although the results of such analysis are highly favorable, those obtained by experimental investigations yield conflicting results, showing only small gains, and sometimes losses. Reduction of this data indicates that there is a lower limit to the quantity of air which must be removed at the slot in order to stabilize the laminar flow. The removal of insufficient air permits transition to occur while the removal of excessive amounts of air results in high power costs, with a net drag increases. With the estimated value of flow coefficient and duct losses equal to half the dynamic pressure, drag reductions of 50% may be obtained; with twice this flow coefficient, the drag saving is reduced to 25%.

  13. Layer-Cake Earth

    ERIC Educational Resources Information Center

    Tedford, Rebecca; Warny, Sophie

    2006-01-01

    In this article, the authors offer a safe, fun, effective way to introduce geology concepts to elementary school children of all ages: "coring" layer cakes. This activity introduces the concepts and challenges that geologists face and at the same time strengthens students' inferential, observational, and problem-solving skills. It also addresses…

  14. ACOUSTIC COMPACTION LAYER DETECTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The depth and strength of compacted layers in fields have been determined traditionally using the ASAE standardized cone penetrometer method. However, an on-the-go method would be much faster and much less labor intensive. The soil measurement system described here attempts to locate the compacted...

  15. Double layers without current

    SciTech Connect

    Perkins, F.W.; Sun, Y.C.

    1980-11-01

    The steady-state solution of the nonlinear Vlasov-Poisson equations is reduced to a nonlinear eigenvalue problem for the case of double-layer (potential drop) boundary conditions. Solutions with no relative electron-ion drifts are found. The kinetic stability is discussed. Suggestions for creating these states in experiments and computer simulations are offered.

  16. Martian Meteor Ionization Layers

    NASA Technical Reports Server (NTRS)

    Grebowsky, J. M.; Pesnell, W. D.

    1999-01-01

    Small interplanetary grains bombard Mars, like all the solar system planets, and, like all the planets with atmospheres, meteoric ion and atom layers form in the upper atmosphere. We have developed a comprehensive one-dimensional model of the Martian meteoric ionization layer including a full chemical scheme. A persistent layer of magnesium ions should exist around an altitude of 70 km. Unlike the terrestrial case, where the metallic ions are formed via charge-exchange with the ambient ions, Mg(+) in the Martian atmosphere is produced by photoionization. Nevertheless, the predicted metal layer peak densities for Earth and Mars are similar. Diffusion solutions, such as those presented here, should be a good approximation of the metallic ions in regions where the magnetic field is negligible and may provide a significant contribution to the nightside ionosphere. The low ultraviolet absorption of the Martian atmosphere may make Mars an excellent laboratory in which to study meteoric ablation. Resonance lines not seen in the spectra of terrestrial meteors may be visible to a surface observatory in the Martian highlands.

  17. Teaching the Double Layer.

    ERIC Educational Resources Information Center

    Bockris, J. O'M.

    1983-01-01

    Suggests various methods for teaching the double layer in electrochemistry courses. Topics addressed include measuring change in absolute potential difference (PD) at interphase, conventional electrode potential scale, analyzing absolute PD, metal-metal and overlap electron PDs, accumulation of material at interphase, thermodynamics of electrified…

  18. MITRE sensor layer prototype

    NASA Astrophysics Data System (ADS)

    Duff, Francis; McGarry, Donald; Zasada, David; Foote, Scott

    2009-05-01

    The MITRE Sensor Layer Prototype is an initial design effort to enable every sensor to help create new capabilities through collaborative data sharing. By making both upstream (raw) and downstream (processed) sensor data visible, users can access the specific level, type, and quantities of data needed to create new data products that were never anticipated by the original designers of the individual sensors. The major characteristic that sets sensor data services apart from typical enterprise services is the volume (on the order of multiple terabytes) of raw data that can be generated by most sensors. Traditional tightly coupled processing approaches extract pre-determined information from the incoming raw sensor data, format it, and send it to predetermined users. The community is rapidly reaching the conclusion that tightly coupled sensor processing loses too much potentially critical information.1 Hence upstream (raw and partially processed) data must be extracted, rapidly archived, and advertised to the enterprise for unanticipated uses. The authors believe layered sensing net-centric integration can be achieved through a standardize-encapsulate-syndicateaggregate- manipulate-process paradigm. The Sensor Layer Prototype's technical approach focuses on implementing this proof of concept framework to make sensor data visible, accessible and useful to the enterprise. To achieve this, a "raw" data tap between physical transducers associated with sensor arrays and the embedded sensor signal processing hardware and software has been exploited. Second, we encapsulate and expose both raw and partially processed data to the enterprise within the context of a service-oriented architecture. Third, we advertise the presence of multiple types, and multiple layers of data through geographic-enabled Really Simple Syndication (GeoRSS) services. These GeoRSS feeds are aggregated, manipulated, and filtered by a feed aggregator. After filtering these feeds to bring just the type

  19. Air pollution directional risk assessment for siting a landfill.

    PubMed

    Chen, Wei-Yea; Kao, Jehng-Jung

    2008-12-01

    Air pollution directional risk (APDR) is an essential factor to be assessed when selecting an appropriate landfill site. Because air pollutants generated from a landfill are diffused and transported by wind in different directions and speeds, areas surrounding the landfill will be subject to different associated risks, depending on their relative position from the landfill. This study assesses potential APDRs imposed from a candidate landfill site on its adjacent areas on the basis of the pollutant distribution simulated by a dispersion model, wind directions and speeds from meteorological monitoring data, and population density. A pollutant distribution map layer was created using a geographic information system and layered onto a population density map to obtain an APDR map layer. The risk map layer was then used in this study to evaluate the suitability of a candidate site for placing a landfill. The efficacy of the proposed procedure was demonstrated for a siting problem in central Taiwan, Republic of China. PMID:19189752

  20. Identification and Tracking of Polluted Air Masses in the South-Central Coast Air Basin.

    NASA Astrophysics Data System (ADS)

    Moore, G. E.; Douglas, S. G.; Kessler, R. C.; Killus, J. P.

    1991-05-01

    Canister samples of air taken during the South-Central Coast Cooperative Air Monitoring Program (SCCCAMP) 1985 field study program were analyzed for concentrations of over 50 hydrocarbons as well as chlorofluorocarbons (CFCs), carbon monoxide, hydrogen, and methane. Additional evidence of location and timing of airmass origin was obtained by utilizing long-lived halocarbons such as F-12 as `tracers of opportunity' in conjunction with known source profiles. Wind trajectories were developed from hourly gridded wind fields produced by a diagnostic wind model utilizing observed wind data. These wind trajectories were used to determine how pollutants from major source areas might be transported to sampling sites. Particulate lidar height-distance traverses were made from aircraft that provided a view of pollutant layering. Mixing height and vertical pollutant concentration distributions were obtained in order to determine if observed pollutant concentrations were consistent with the degree of stagnation present and hypothesized transport pathway.Analyses to track specific polluted air masses were conducted for the 13 September, 21 September, 23-24 September, and 2-3 October 1985 intensive study periods. The analyses find that elevated ozone concentrations during these periods are primarily attributed to transport and storage of ozone-enriched air from Los Angeles. During one type of episode (2-3 October) ozone and ozone precursors are stored near the surface over the Santa Barbara Channel overnight and transported into coastal areas on the following day. In another type of episode (23-24 September) ozone is transported into the study domain from the San Fernando Valley and Los Angeles via flow around the Santa Monica Hills. Transport of pollutant-enriched air takes place in a layer 200-500 m aloft, in many places overlaying cleaner marine-layer air. This advected ozone is mixed down to contribute to ground-level ozone concentrations over terrain where the marine layer