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Sample records for no2 columns derived

  1. Top-down NOX Emissions of European Cities Derived from Modelled and Spaceborne Tropospheric NO2 Columns

    Science.gov (United States)

    Verstraeten, W. W.; Boersma, K. F.; Douros, J.; Williams, J. E.; Eskes, H.; Delcloo, A. W.

    2017-12-01

    High nitrogen oxides (NOX = NO + NO2) concentrations near the surface impact humans and ecosystems badly and play a key role in tropospheric chemistry. NO2 is an important precursor of tropospheric ozone (O3) which in turn affects the production of the hydroxyl radical controlling the chemical lifetime of key atmospheric pollutants and reactive greenhouse gases. Combustion from industrial, traffic and household activities in large and densely populated urban areas result in high NOX emissions. Accurate mapping of these emissions is essential but hard to do since reported emissions factors may differ from real-time emissions in order of magnitude. Modelled NO2 levels and lifetimes also have large associated uncertainties and overestimation in the chemical lifetime which may mask missing NOX chemistry in current chemistry transport models (CTM's). The simultaneously estimation of both the NO2 lifetime and as well as the concentrations by applying the Exponentially Modified Gaussian (EMG) method on tropospheric NO2 columns lines densities should improve the surface NOX emission estimates. Here we evaluate if the EMG methodology applied on the tropospheric NO2 columns simulated by the LOTOS-EUROS (Long Term Ozone Simulation-European Ozone Simulation) CTM can reproduce the NOX emissions used as model input. First we process both the modelled tropospheric NO2 columns for the period April-September 2013 for 21 selected European urban areas under windy conditions (averaged vertical wind speeds between surface and 500 m from ECMWF > 2 m s-1) as well as the accompanying OMI (Ozone Monitoring Instrument) data providing us with real-time observation-based estimates of midday NO2 columns. Then we compare the top-down derived surface NOX emissions with the 2011 MACC-III emission inventory, used in the CTM as input to simulate the NO2 columns. For cities where NOX emissions can be assumed as originating from one large source good agreement is found between the top-down derived

  2. Global NOx emission estimates derived from an assimilation of OMI tropospheric NO2 columns

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    K. Sudo

    2012-03-01

    Full Text Available A data assimilation system has been developed to estimate global nitrogen oxides (NOx emissions using OMI tropospheric NO2 columns (DOMINO product and a global chemical transport model (CTM, the Chemical Atmospheric GCM for Study of Atmospheric Environment and Radiative Forcing (CHASER. The data assimilation system, based on an ensemble Kalman filter approach, was applied to optimize daily NOx emissions with a horizontal resolution of 2.8° during the years 2005 and 2006. The background error covariance estimated from the ensemble CTM forecasts explicitly represents non-direct relationships between the emissions and tropospheric columns caused by atmospheric transport and chemical processes. In comparison to the a priori emissions based on bottom-up inventories, the optimized emissions were higher over eastern China, the eastern United States, southern Africa, and central-western Europe, suggesting that the anthropogenic emissions are mostly underestimated in the inventories. In addition, the seasonality of the estimated emissions differed from that of the a priori emission over several biomass burning regions, with a large increase over Southeast Asia in April and over South America in October. The data assimilation results were validated against independent data: SCIAMACHY tropospheric NO2 columns and vertical NO2 profiles obtained from aircraft and lidar measurements. The emission correction greatly improved the agreement between the simulated and observed NO2 fields; this implies that the data assimilation system efficiently derives NOx emissions from concentration observations. We also demonstrated that biases in the satellite retrieval and model settings used in the data assimilation largely affect the magnitude of estimated emissions. These dependences should be carefully considered for better understanding NOx sources from top-down approaches.

  3. Comparison of GOME tropospheric NO2 columns with NO2 profiles deduced from ground-based in situ measurements

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    Schaub, D.; Boersma, K. F.; Kaiser, J. W.; Weiss, A. K.; Folini, D.; Eskes, H. J.; Buchmann, B.

    2006-08-01

    Nitrogen dioxide (NO2) vertical tropospheric column densities (VTCs) retrieved from the Global Ozone Monitoring Experiment (GOME) are compared to coincident ground-based tropospheric NO2 columns. The ground-based columns are deduced from in situ measurements at different altitudes in the Alps for 1997 to June 2003, yielding a unique long-term comparison of GOME NO2 VTC data retrieved by a collaboration of KNMI (Royal Netherlands Meteorological Institute) and BIRA/IASB (Belgian Institute for Space Aeronomy) with independently derived tropospheric NO2 profiles. A first comparison relates the GOME retrieved tropospheric columns to the tropospheric columns obtained by integrating the ground-based NO2 measurements. For a second comparison, the tropospheric profiles constructed from the ground-based measurements are first multiplied with the averaging kernel (AK) of the GOME retrieval. The second approach makes the comparison independent from the a priori NO2 profile used in the GOME retrieval. This allows splitting the total difference between the column data sets into two contributions: one that is due to differences between the a priori and the ground-based NO2 profile shapes, and another that can be attributed to uncertainties in both the remaining retrieval parameters (such as, e.g., surface albedo or aerosol concentration) and the ground-based in situ NO2 profiles. For anticyclonic clear sky conditions the comparison indicates a good agreement between the columns (n=157, R=0.70/0.74 for the first/second comparison approach, respectively). The mean relative difference (with respect to the ground-based columns) is -7% with a standard deviation of 40% and GOME on average slightly underestimating the ground-based columns. Both data sets show a similar seasonal behaviour with a distinct maximum of spring NO2 VTCs. Further analysis indicates small GOME columns being systematically smaller than the ground-based ones. The influence of different shapes in the a priori and

  4. Comparison of GOME tropospheric NO2 columns with NO2 profiles deduced from ground-based in situ measurements

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    D. Schaub

    2006-01-01

    Full Text Available Nitrogen dioxide (NO2 vertical tropospheric column densities (VTCs retrieved from the Global Ozone Monitoring Experiment (GOME are compared to coincident ground-based tropospheric NO2 columns. The ground-based columns are deduced from in situ measurements at different altitudes in the Alps for 1997 to June 2003, yielding a unique long-term comparison of GOME NO2 VTC data retrieved by a collaboration of KNMI (Royal Netherlands Meteorological Institute and BIRA/IASB (Belgian Institute for Space Aeronomy with independently derived tropospheric NO2 profiles. A first comparison relates the GOME retrieved tropospheric columns to the tropospheric columns obtained by integrating the ground-based NO2 measurements. For a second comparison, the tropospheric profiles constructed from the ground-based measurements are first multiplied with the averaging kernel (AK of the GOME retrieval. The second approach makes the comparison independent from the a priori NO2 profile used in the GOME retrieval. This allows splitting the total difference between the column data sets into two contributions: one that is due to differences between the a priori and the ground-based NO2 profile shapes, and another that can be attributed to uncertainties in both the remaining retrieval parameters (such as, e.g., surface albedo or aerosol concentration and the ground-based in situ NO2 profiles. For anticyclonic clear sky conditions the comparison indicates a good agreement between the columns (n=157, R=0.70/0.74 for the first/second comparison approach, respectively. The mean relative difference (with respect to the ground-based columns is −7% with a standard deviation of 40% and GOME on average slightly underestimating the ground-based columns. Both data sets show a similar seasonal behaviour with a distinct maximum of spring NO2 VTCs. Further analysis indicates small GOME columns being systematically smaller than the ground-based ones. The influence of different shapes in the a

  5. NO2 column changes induced by volcanic eruptions

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    Johnston, Paul V.; Keys, J. Gordon; Mckenzie, Richard L.

    1994-01-01

    Nitrogen dioxide slant column amounts measured by ground-based remote sensing from Lauder, New Zealand (45 deg S) and Campbell Island (53 deg S) during the second half of 1991 and early 1992 show anomalously low values that are attributed to the effects of volcanic eruptions. It is believed that the eruptions of Mount Pinatubo in the Philippines in June 1991 and possibly Mount Hudson in Chile in August 1991 are responsible for the stratospheric changes, which first became apparent in July 1991. The effects in the spring of 1991 are manifested as a reduction in the retrieved NO2 column amounts from normal levels by 35 to 45 percent, and an accompanying increase in the overnight decay of NO2. The existence of an accurate long-term record of column NO2 from the Lauder site enables us to quantify departures from the normal seasonal behavior with some confidence. Simultaneous retrievals of column ozone agree well with Dobson measurements, confirming that only part of the NO2 changes can be attributed to a modification of the scattering geometry by volcanic aerosols. Other reasons for the observed behavior are explored, including the effects of stratospheric temperature increases resulting from the aerosol loading and the possible involvement of heterogeneous chemical processes.

  6. Evaluation of OMI operational standard NO2 column retrievals using in situ and surface-based NO2 observations

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    L. N. Lamsal

    2014-11-01

    Full Text Available We assess the standard operational nitrogen dioxide (NO2 data product (OMNO2, version 2.1 retrieved from the Ozone Monitoring Instrument (OMI onboard NASA's Aura satellite using a combination of aircraft and surface in~situ measurements as well as ground-based column measurements at several locations and a bottom-up NOx emission inventory over the continental US. Despite considerable sampling differences, NO2 vertical column densities from OMI are modestly correlated (r = 0.3–0.8 with in situ measurements of tropospheric NO2 from aircraft, ground-based observations of NO2 columns from MAX-DOAS and Pandora instruments, in situ surface NO2 measurements from photolytic converter instruments, and a bottom-up NOx emission inventory. Overall, OMI retrievals tend to be lower in urban regions and higher in remote areas, but generally agree with other measurements to within ± 20%. No consistent seasonal bias is evident. Contrasting results between different data sets reveal complexities behind NO2 validation. Since validation data sets are scarce and are limited in space and time, validation of the global product is still limited in scope by spatial and temporal coverage and retrieval conditions. Monthly mean vertical NO2 profile shapes from the Global Modeling Initiative (GMI chemistry-transport model (CTM used in the OMI retrievals are highly consistent with in situ aircraft measurements, but these measured profiles exhibit considerable day-to-day variation, affecting the retrieved daily NO2 columns by up to 40%. This assessment of OMI tropospheric NO2 columns, together with the comparison of OMI-retrieved and model-simulated NO2 columns, could offer diagnostic evaluation of the model.

  7. Accounting for surface reflectance in the derivation of vertical column densities of NO2 from airborne imaging DOAS

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    Meier, Andreas Carlos; Schönhardt, Anja; Richter, Andreas; Bösch, Tim; Seyler, André; Constantin, Daniel Eduard; Shaiganfar, Reza; Merlaud, Alexis; Ruhtz, Thomas; Wagner, Thomas; van Roozendael, Michel; Burrows, John. P.

    2016-04-01

    Nitrogen oxides, NOx (NOx = NO + NO2) play a key role in tropospheric chemistry. In addition to their directly harmful effects on the respiratory system of living organisms, they influence the levels of tropospheric ozone and contribute to acid rain and eutrophication of ecosystems. As they are produced in combustion processes, they can serve as an indicator for anthropogenic air pollution. In the late summers of 2014 and 2015, two extensive measurement campaigns were conducted in Romania by several European research institutes, with financial support from ESA. The AROMAT / AROMAT-2 campaigns (Airborne ROmanian Measurements of Aerosols and Trace gases) were dedicated to measurements of air quality parameters utilizing newly developed instrumentation at state-of-the-art. The experiences gained will help to calibrate and validate the measurements taken by the upcoming Sentinel-S5p mission scheduled for launch in 2016. The IUP Bremen contributed to these campaigns with its airborne imaging DOAS (Differential Optical Absorption Spectroscopy) instrument AirMAP (Airborne imaging DOAS instrument for Measurements of Atmospheric Pollution). AirMAP allows retrieving spatial distributions of trace gas columns densities in a stripe below the aircraft. The measurements have a high spatial resolution of approximately 30 x 80 m2 (along x across track) at a typical flight altitude of 3000 m. Supported by the instrumental setup and the large swath, gapless maps of trace gas distributions above a large city, like Bucharest or Berlin, can be acquired within a time window of approximately two hours. These properties make AirMAP a valuable tool for the validation of trace gas measurements from space. DOAS retrievals yield the density of absorbers integrated along the light path of the measurement. The light path is altered with a changing surface reflectance, leading to enhanced / reduced slant column densities of NO2 depending on surface properties. This effect must be considered in

  8. MAX-DOAS measurements of NO2 column densities in Vienna

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    Schreier, Stefan; Weihs, Philipp; Peters, Enno; Richter, Andreas; Ostendorf, Mareike; Schönhardt, Anja; Burrows, John P.; Schmalwieser, Alois

    2017-04-01

    In the VINDOBONA (VIenna horizontal aNd vertical Distribution OBservations Of Nitrogen dioxide and Aerosols) project, two Multi AXis Differential Optical Absorption Spectroscopy (MAX-DOAS) systems will be set up at two different locations and altitudes in Vienna, Austria. After comparison measurements in Bremen, Germany, and Cabauw, The Netherlands, the first of the two MAX-DOAS instruments was set up at the University of Veterinary Medicine in the northeastern part of Vienna in December 2016. The instrument performs spectral measurements of visible scattered sunlight at defined horizontal and vertical viewing directions. From these measurements, column densities of NO2 and aerosols are derived by applying the DOAS analysis. First preliminary results are presented. The second MAX-DOAS instrument will be set up in April/May 2017 at the University of Natural Resources and Life Sciences in the northwestern part of Vienna. Once these two instruments are measuring simultaneously, small campaigns including car DOAS zenith-sky and tower DOAS off-axis measurements are planned. The main emphasis of this project will be on the installation and operation of two MAX-DOAS instruments, the improvement of tropospheric NO2 and aerosol retrieval, and the characterization of the horizontal, vertical, and temporal variations of tropospheric NO2 and aerosols in Vienna, Austria.

  9. Satellite derived trends in NO2 over the major global hotspot regions during the past decade and their inter-comparison

    International Nuclear Information System (INIS)

    Ghude, Sachin D.; Van der A, R.J.; Beig, G.; Fadnavis, S.; Polade, S.D.

    2009-01-01

    We assessed satellite derived tropospheric NO 2 distribution on a global scale and identified the major NO 2 hotspot regions. Combined GOME and SCIAMACHY measurements for the period 1996-2006 have been used to compute the trends over these regions. Our analysis shows that tropospheric NO 2 column amounts have increased over the newly and rapidly developing regions like China (11 ± 2.6%/year), south Asia (1.76 ± 1.1%/year), Middle East (2.3 ± 1%/year) and South Africa (2.4 ± 2.2%/year). Tropospheric NO 2 column amounts show some decrease over the eastern US (-2 ± 1.5%/year) and Europe (0.9 ± 2.1%/year). We found that although tropospheric NO 2 column amounts decreased over the major developed regions in the past decade, the present tropospheric NO 2 column amounts over these regions are still significantly higher than those observed over newly and rapidly developing regions (except China). Tropospheric NO 2 column amounts show some decrease over South America and Central Africa, which are major biomass burning regions in the Southern Hemisphere. - Trends in tropospheric column NO 2 over newly developing regions.

  10. Observation of slant column NO2 using the super-zoom mode of AURA-OMI

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    Valin, L.C.; Russell, A.R.; Bucsela, E.J.; Veefkind, J.P.; Cohen, R.C.

    2011-01-01

    We retrieve slant column NO2 from the superzoom mode of the Ozone Monitoring Instrument (OMI) to explore its utility for understanding NOx emissions and variability. Slant column NO2 is operationally retrieved from OMI (Boersma et al., 2007; Bucsela et al., 2006) with a nadir footprint of 13×24 km2,

  11. Intra-pixel variability in satellite tropospheric NO2 column densities derived from simultaneous space-borne and airborne observations over the South African Highveld

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    Broccardo, Stephen; Heue, Klaus-Peter; Walter, David; Meyer, Christian; Kokhanovsky, Alexander; van der A, Ronald; Piketh, Stuart; Langerman, Kristy; Platt, Ulrich

    2018-05-01

    Aircraft measurements of NO2 using an imaging differential optical absorption spectrometer (iDOAS) instrument over the South African Highveld region in August 2007 are presented and compared to satellite measurements from OMI and SCIAMACHY. In situ aerosol and trace-gas vertical profile measurements, along with aerosol optical thickness and single-scattering albedo measurements from the Aerosol Robotic Network (AERONET), are used to devise scenarios for a radiative transfer modelling sensitivity study. Uncertainty in the air-mass factor due to variations in the aerosol and NO2 profile shape is constrained and used to calculate vertical column densities (VCDs), which are compared to co-located satellite measurements. The lower spatial resolution of the satellites cannot resolve the detailed plume structures revealed in the aircraft measurements. The airborne DOAS in general measured steeper horizontal gradients and higher peak NO2 vertical column density. Aircraft measurements close to major sources, spatially averaged to the satellite resolution, indicate NO2 column densities more than twice those measured by the satellite. The agreement between the high-resolution aircraft instrument and the satellite instrument improves with distance from the source, this is attributed to horizontal and vertical dispersion of NO2 in the boundary layer. Despite the low spatial resolution, satellite images reveal point sources and plumes that retain their structure for several hundred kilometres downwind.

  12. On the use of satellite-derived CH4 : CO2 columns in a joint inversion of CH4 and CO2 fluxes

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    Pandey, S.

    2015-01-01

    We present a method for assimilating total column CH4 : CO2 ratio measurements from satellites for inverse modeling of CH4 and CO2 fluxes using the variational approach. Unlike conventional approaches, in which retrieved CH4 : CO2 are multiplied by model-derived total column CO2 and only the

  13. Observation of slant column NO2 using the super-zoom mode of AURA-OMI

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    R. C. Cohen

    2011-09-01

    Full Text Available We retrieve slant column NO2 from the super-zoom mode of the Ozone Monitoring Instrument (OMI to explore its utility for understanding NOx emissions and variability. Slant column NO2 is operationally retrieved from OMI (Boersma et al., 2007; Bucsela et al., 2006 with a nadir footprint of 13 × 24 km2, the result of averaging eight detector elements on board the instrument. For 85 orbits in late 2004, OMI reported observations from individual "super-zoom" detector elements (spaced at 13 × 3 km2 at nadir. We assess the spatial response of these individual detector elements in-flight and determine an upper-bound on spatial resolution of 9 km, in good agreement with on-ground calibration (7 km FWHM. We determine the precision of the super-zoom mode to be 2.1 × 1015 molecules cm−2, approximately a factor of √8 lower than an identical retrieval at operational scale as expected if random noise dominates the uncertainty. We retrieve slant column NO2 over the Satpura power plant in India; Seoul, South Korea; Dubai, United Arab Emirates; and a set of large point sources on the Rihand Reservoir in India using differential optical absorption spectroscopy (DOAS. Over these sources, the super-zoom mode of OMI observes variation in slant column NO2 of up to 30 × the instrumental precision within one operational footprint.

  14. Characterizing boundary layer height using surface and column measurements of NO2 and formaldehyde

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    Valin, L.; Szykman, J.; Long, R.; Whitehill, A.; Williams, D. J.; Knepp, T. N.; Crawford, J. H.; Al-Saadi, J. A.; Judd, L.; Brown, S.; Matichuk, R.; Tonnesen, G.; Appel, W.; Hogrefe, C.; Abuhassan, N.; Cede, A.; Spinei, E.; Herman, J. R.; Swap, R.; Cohen, R. C.; Fried, A.; Weinheimer, A. J.

    2017-12-01

    The rate of vertical mixing near the surface determines the rate of human exposure to emitted pollutants and also influences the rate at which ozone and particulate matter are formed. To characterize the variability of atmospheric composition near the surface and above, the EPA Office of Research and Development has deployed instruments to measure surface and column concentrations of NO2, an emitted species, and formaldehyde (HCHO) during KORUS-AQ (May - June 2016, Seoul, Korea), UWFPS (Jan-Feb 2016, Salt Lake City) and LMOS (May - June, 2017, Lake Michigan). We compare the mixed layer height determined by aerosol backscatter profiles to a value determined by dividing the NO2 and HCHO column density (molecule cm-2) by its surface concentration (molecule cm-3), using linear regression to remove influence of layers aloft (y-intercept), such as subtraction of the stratospheric NO2 column. We evaluate our findings by using aircraft soundings of NO2 and HCHO and discuss the implications with respect to photochemical transport modeling results from CMAQ and space-based satellite retrievals. Finally we discuss an overall strategy to make these measurements part of routine monitoring at Photochemical Assessment Monitoring System locations (PAMS).

  15. Determination of tropospheric vertical columns of NO2 and aerosol optical properties in a rural setting using MAX-DOAS

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    M. O. Wenig

    2011-12-01

    Full Text Available Multi-AXis Differential Optical Absorption Spectroscopy (MAX-DOAS measurements were performed in a rural location of southwestern Ontario during the Border Air Quality and Meteorology Study. Slant column densities (SCDs of NO2 and O4 were determined using the standard DOAS technique. Using a radiative transfer model and the O4 SCDs, aerosol optical depths were determined for clear sky conditions and compared to OMI, MODIS, AERONET, and local PM2.5 measurements. This aerosol information was input to a radiative transfer model to calculate NO2 air mass factors, which were fit to the measured NO2 SCDs to determine tropospheric vertical column densities (VCDs of NO2. The method of determining NO2 VCDs in this way was validated for the first time by comparison to composite VCDs derived from aircraft and ground-based measurements of NO2. The new VCDs were compared to VCDs of NO2 determined via retrievals from the satellite instruments SCIAMACHY and OMI, for overlapping time periods. The satellite-derived VCDs were higher, with a mean bias of +0.5–0.9×1015 molec cm−2. This last finding is different from previous studies whereby MAX-DOAS geometric VCDs were higher than satellite determinations, albeit for urban areas with higher VCDs. An effective boundary layer height, BLHeff, is defined as the ratio of the tropospheric VCD and the ground level concentration of NO2. Variations of BLHeff can be linked to time of day, source region, stability of the atmosphere, and the presence or absence of elevated NOx sources. In particular, a case study is shown where a high VCD and BLHeff were observed when an elevated industrial plume of NOx and SO2 was fumigated to the surface as a lake breeze impacted the measurement site. High BLHeff values (~1.9 km were observed during a regional smog event when high winds from the SW and high convection promoted mixing throughout the boundary layer. During this event, the regional line flux of NO2 through the region was

  16. Validation of GOME (ERS-2) NO2 vertical column data with ground-based measurements at Issyk-Kul (Kyrgyzstan)

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    Ionov, D.; Sinyakov, V.; Semenov, V.

    Starting from 1995 the global monitoring of atmospheric nitrogen dioxide is carried out by the measurements of nadir-viewing GOME spectrometer aboard ERS-2 satellite. Continuous validation of that data by means of comparisons with well-controlled ground-based measurements is important to ensure the quality of GOME data products and improve related retrieval algorithms. At the station of Issyk-Kul (Kyrgyzstan) the ground-based spectroscopic observations of NO2 vertical column have been started since 1983. The station is located on the northern shore of Issyk-Kul lake, 1650 meters above the sea level (42.6 N, 77.0 E). The site is equipped with grating spectrometer for the twilight measurements of zenith-scattered solar radiation in the visible range, and applies the DOAS technique to retrieve NO2 vertical column. It is included in the list of NDSC stations as a complementary one. The present study is focused on validation of GOME NO2 vertical column data, based on 8-year comparison with correlative ground-based measurements at Issyk-Kul station in 1996-2003. Within the investigation, an agreement of both individual and monthly averaged GOME measurements with corresponding twilight ground-based observations is examined. Such agreement is analyzed with respect to different conditions (season, sun elevation), temporal/spatial criteria choice (actual overpass location, correction for diurnal variation) and data processing (GDP version 2.7, 3.0). In addition, NO2 vertical columns were integrated from simultaneous stratospheric profile measurements by NASA HALOE and SAGE-II/III satellite instruments and introduced to explain the differences with ground-based observations. In particular cases, NO2 vertical profiles retrieved from the twilight ground-based measurements at Issuk-Kul were also included into comparison. Overall, summertime GOME NO2 vertical columns were found to be systematicaly lower than ground-based data. This work was supported by International Association

  17. Long-term changes of tropospheric NO2 over megacities derived from multiple satellite instruments

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    A. Hilboll

    2013-04-01

    Full Text Available Tropospheric NO2, a key pollutant in particular in cities, has been measured from space since the mid-1990s by the GOME, SCIAMACHY, OMI, and GOME-2 instruments. These data provide a unique global long-term dataset of tropospheric pollution. However, the observations differ in spatial resolution, local time of measurement, viewing geometry, and other details. All these factors can severely impact the retrieved NO2 columns. In this study, we present three ways to account for instrumental differences in trend analyses of the NO2 columns derived from satellite measurements, while preserving the individual instruments' spatial resolutions. For combining measurements from GOME and SCIAMACHY into one consistent time series, we develop a method to explicitly account for the instruments' difference in ground pixel size (40 × 320 km2 vs. 30 × 60 km2. This is especially important when analysing NO2 changes over small, localised sources like, e.g. megacities. The method is based on spatial averaging of the measured earthshine spectra and extraction of a spatial pattern of the resolution effect. Furthermore, two empirical corrections, which summarise all instrumental differences by including instrument-dependent offsets in a fitted trend function, are developed. These methods are applied to data from GOME and SCIAMACHY separately, to the combined time series, and to an extended dataset comprising also GOME-2 and OMI measurements. All approaches show consistent trends of tropospheric NO2 for a selection of areas on both regional and city scales, for the first time allowing consistent trend analysis of the full time series at high spatial resolution. Compared to previous studies, the longer study period leads to significantly reduced uncertainties. We show that measured tropospheric NO2 columns have been strongly increasing over China, the Middle East, and India, with values over east-central China tripling from 1996 to 2011. All parts of the developed world

  18. Mobile Column Measurements of HCHO, NO2, NH3, and C2H6 in Colorado during FRAPPE

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    Kille, N.; Volkamer, R. M.; Baidar, S.; Ortega, I.; Sinreich, R.; Hannigan, J. W.; Cooper, O. R.; Nussbaumer, E.; Pfister, G.

    2015-12-01

    Gases from anthropogenic sources have the potential to have a profound impact on air quality. Emissions from large cattle feedlots and ONG (Oil and Natural Gas) sites are comprised of NH3 (ammonia) and C2H6 (ethane) as pollutants. C2H6 contributes to photochemical ozone (O3) production and oxidation production of HCHO (formaldehyde). NH3 is a major source for reactive nitrogen to form particulate matter 2.5, which negatively affects human health. NO2 (nitrogen dioxide), emitted during combustion, is considered a large-scale pollutant and contributes to the formation of O3. Deploying an innovative suite of remote sensing instruments in a mobile laboratory, a Multi Axis Differential Optical Absorption Spectrometer (MAX-DOAS), a UV-Vis Spectrometer, and a Fourier Transform Infrared Spectrometer, we obtain mobile column measurements at high spatial and temporal resolution, 2 seconds for the UV-Vis and IR spectrometers and 20 seconds for the MAX-DOAS. Within the scope of the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) we measure total columns of HCHO, NO2, NH3, and C2H6 using the University of Colorado mobile laboratory. Emissions of urban areas, agriculture, and ONG sites were studied. For the measurement of total columns the solar occultation flux method has been applied. We measured significant variability in the columns. The measurement of total columns allows one to determine the emission flux and source strength when driving a closed box around or upwind and downwind of a source with the mobile laboratory. We present results from select research drives.

  19. Characterization of wildfire NOx emissions using MODIS fire radiative power and OMI tropospheric NO2 columns

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    R. C. Cohen

    2011-06-01

    Full Text Available We use observations of fire radiative power (FRP from the Moderate Resolution Imaging Spectroradiometer~(MODIS and tropospheric NO2 column measurements from the Ozone Monitoring Instrument (OMI to derive NO2 wildfire emission coefficients (g MJ−1 for three land types over California and Nevada. Retrieved emission coefficients were 0.279±0.077, 0.342±0.053, and 0.696±0.088 g MJ−1 NO2 for forest, grass and shrub fuels, respectively. These emission coefficients reproduce ratios of emissions with fuel type reported previously using independent methods. However, the magnitude of these coefficients is lower than prior estimates. While it is possible that a negative bias in the OMI NO2 retrieval over regions of active fire emissions is partly responsible, comparison with several other studies of fire emissions using satellite platforms indicates that current emission factors may overestimate the contributions of flaming combustion and underestimate the contributions of smoldering combustion to total fire emissions. Our results indicate that satellite data can provide an extensive characterization of the variability in fire NOx emissions; 67 % of the variability in emissions in this region can be accounted for using an FRP-based parameterization.

  20. Spatial and Temporal Variability of Ground and Satellite Column Measurements of NO2 and O3 over the Atlantic Ocean During the Deposition of Atmospheric Nitrogen to Coastal Ecosystems Experiment

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    Martins, Douglas K.; Najjar, Raymond G.; Tzortziou, Maria; Abuhassan, Nader; Thompson, Anne M.; Kollonige, Debra E.

    2016-01-01

    In situ measurements of O3 and nitrogen oxides (NO + NO2=NOx) and remote sensing measurements of total column NO2 and O3 were collected on a ship in the North Atlantic Ocean as part of the Deposition of Atmospheric Nitrogen to Coastal Ecosystems (DANCE) campaign in July August 2014,100 km east of the mid-Atlantic United States. Relatively clean conditions for both surface in situ mixing ratio and total column O3 and NO2 measurements were observed throughout the campaign. Increased surface and column NO2 and O3 amounts were observed when a terrestrial air mass was advected over the study region. Relative to ship-based total column measurements using a Pandora over the entire study, satellite measurements overestimated total column NO2 under these relatively clean atmospheric conditions over offshore waters by an average of 16. Differences are most likely due to proximity, or lack thereof, to surface emissions; spatial averaging due to the field of view of the satellite instrument; and the lack of sensitivity of satellite measurements to the surface concentrations of pollutants. Total column O3 measurements from the shipboard Pandora showed good correlation with the satellite measurements(r 0.96), but satellite measurements were 3 systematically higher than the ship measurements, in agreement with previous studies. Derived values of boundary layer height using the surface in situ and total column measurements of NO2 are much lower than modeled and satellite-retrieved boundary layer heights, which highlight the differences in the vertical distribution between terrestrial and marine environments.

  1. The Effects of Aerosol on the Retrieval Accuracy of NO2 Slant Column Density

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    Hyunkee Hong

    2017-08-01

    Full Text Available We investigate the effects of aerosol optical depth (AOD, single scattering albedo (SSA, aerosol peak height (APH, measurement geometry (solar zenith angle (SZA and viewing zenith angle (VZA, relative azimuth angle, and surface reflectance on the accuracy of NO2 slant column density using synthetic radiance. High AOD and APH are found to decrease NO2 SCD retrieval accuracy. In moderately polluted (5 × 1015 molecules cm−2 < NO2 vertical column density (VCD < 2 × 1016 molecules cm−2 and clean regions (NO2 VCD < 5 × 1015 molecules cm−2, the correlation coefficient (R between true NO2 SCDs and those retrieved is 0.88 and 0.79, respectively, and AOD and APH are about 0.1 and is 0 km, respectively. However, when AOD and APH are about 1.0 and 4 km, respectively, the R decreases to 0.84 and 0.53 in moderately polluted and clean regions, respectively. On the other hand, in heavily polluted regions (NO2 VCD > 2 × 1016 molecules cm−2, even high AOD and APH values are found to have a negligible effect on NO2 SCD precision. In high AOD and APH conditions in clean NO2 regions, the R between true NO2 SCDs and those retrieved increases from 0.53 to 0.58 via co-adding four pixels spatially, showing the improvement in accuracy of NO2 SCD retrieval. In addition, the high SZA and VZA are also found to decrease the accuracy of the NO2 SCD retrieval.

  2. Estimating 40 years of nitrogen deposition in global biomes using the SCIAMACHY NO2 column

    Science.gov (United States)

    Lu, Xuehe; Zhang, Xiuying; Liu, Jinxun; Jin, Jiaxin

    2016-01-01

    Owing to human activity, global nitrogen (N) cycles have been altered. In the past 100 years, global N deposition has increased. Currently, the monitoring and estimating of N deposition and the evaluation of its effects on global carbon budgets are the focus of many researchers. NO2 columns retrieved by space-borne sensors provide us with a new way of exploring global N cycles and these have the ability to estimate N deposition. However, the time range limitation of NO2 columns makes the estimation of long timescale N deposition difficult. In this study we used ground-based NOx emission data to expand the density of NO2columns, and 40 years of N deposition (1970–2009) was inverted using the multivariate linear model with expanded NO2 columns. The dynamic of N deposition was examined in both global and biome scales. The results show that the average N deposition was 0.34 g N m–2 year–1 in the 2000s, which was an increase of 38.4% compared with the 1970s’. The total N deposition in different biomes is unbalanced. N deposition is only 38.0% of the global total in forest biomes; this is made up of 25.9%, 11.3, and 0.7% in tropical, temperate, and boreal forests, respectively. As N-limited biomes, there was little increase of N deposition in boreal forests. However, N deposition has increased by a total of 59.6% in tropical forests and croplands, which are N-rich biomes. Such characteristics may influence the effects on global carbon budgets.

  3. Impacts of control strategies, the Great Recession and weekday variations on NO2 columns above North American cities

    Science.gov (United States)

    de Foy, Benjamin; Lu, Zifeng; Streets, David G.

    2016-08-01

    The Ozone Monitoring Instrument (OMI) has been estimating NO2 columns from space for over 10 years, and these have been used to estimate emissions and emission trends for point and area sources all over the world. In this study we evaluate the trends in NO2 columns over 54 cities in the USA and Canada to identify the long term trends due to air quality policies, the impact of the Great Recession, and the weekday-weekend effect. A multiple linear regression model is used to fit annual, seasonal and weekly factors for individual swath retrievals along with the impact of temperature, wind speed and pixel size. For most cities, the correlation coefficients of the model fit ranges from 0.47 to 0.76. There have been strong reductions in NO2 columns, with annual decreases of up to 7% per year in most cities. During the years of the Great Recession, NO2 columns were as much as 30% lower than they would have been had they followed the linear annual trend. The analysis yielded insights into the timing of the reductions, with some cities in the northwest and in the east experiencing reductions in 2008 already, and most areas back to where they would have been based on the uniform trend by 2011. The analysis also finds that reductions in columns during the weekend vary significantly from city to city, with a range in reductions of 10%-30% on Saturdays, and 20%-50% on Sundays.

  4. Impacts of control strategies, the Great Recession and weekday variations on NO 2 columns above North American cities

    Energy Technology Data Exchange (ETDEWEB)

    de Foy, Benjamin; Lu, Zifeng; Streets, David G.

    2016-08-01

    The Ozone Monitoring Instrument (OMI) has been estimating NO2 columns from space for over 10 years, and these have been used to estimate emissions and emission trends for point and area sources all over the world. In this study we evaluate the trends in NO2 columns over 54 cities in the USA and Canada to identify the long term trends due to air quality policies, the impact of the Great Recession, and the weekday-weekend effect. A multiple linear regression model is used to fit annual, seasonal and weekly factors for individual swath retrievals along with the impact of temperature, wind speed and pixel size. For most cities, the correlation coefficients of the model fit ranges from 0.47 to 0.76. There have been strong reductions in NO2 columns, with annual decreases of up to 7% per year in most cities. During the years of the Great Recession, NO2 columns were as much as 30% lower than they would have been had they followed the linear annual trend. The analysis yielded insights into the timing of the reductions, with some cities in the northwest and in the east experiencing reductions in 2008 already, and most areas back to where they would have been based on the uniform trend by 2011. The analysis also finds that reductions in columns during the weekend vary significantly from city to city, with a range in reductions of 10%-30% on Saturdays, and 20%-50% on Sundays.

  5. A New ENSO Index Derived from Satellite Measurements of Column Ozone

    Science.gov (United States)

    Ziemke, J. R.; Chandra, S.; Oman, L. D.; Bhartia, P. K.

    2010-01-01

    Column Ozone measured in tropical latitudes from Nimbus 7 total ozone mapping spectrometer (TOMS), Earth Probe TOMS, solar backscatter ultraviolet (SBUV), and Aura ozone monitoring instrument (OMI) are used to derive an El Nino-Southern Oscillation (ENSO) index. This index, which covers a time period from 1979 to the present, is defined as the Ozone ENSO Index (OEI) and is the first developed from atmospheric trace gas measurements. The OEI is constructed by first averaging monthly mean column ozone over two broad regions in the western and eastern Pacific and then taking their difference. This differencing yields a self-calibrating ENSO index which is independent of individual instrument calibration offsets and drifts in measurements over the long record. The combined Aura OMI and MLS ozone data confirm that zonal variability in total column ozone in the tropics caused by ENSO events lies almost entirely in the troposphere. As a result, the OEI can be derived directly from total column ozone instead of tropospheric column ozone. For clear-sky ozone measurements a +1K change in Nino 3.4 index corresponds to +2.9 Dobson Unit (DU) change in the OEI, while a +1 hPa change in SOI coincides with a -1.7DU change in the OEI. For ozone measurements under all cloud conditions these numbers are +2.4DU and -1.4 DU, respectively. As an ENSO index based upon ozone, it is potentially useful in evaluating climate models predicting long term changes in ozone and other trace gases.

  6. Modeling of tropospheric NO2 column over different climatic zones and land use/land cover types in South Asia

    Science.gov (United States)

    ul-Haq, Zia; Rana, Asim Daud; Tariq, Salman; Mahmood, Khalid; Ali, Muhammad; Bashir, Iqra

    2018-03-01

    We have applied regression analyses for the modeling of tropospheric NO2 (tropo-NO2) as the function of anthropogenic nitrogen oxides (NOx) emissions, aerosol optical depth (AOD), and some important meteorological parameters such as temperature (Temp), precipitation (Preci), relative humidity (RH), wind speed (WS), cloud fraction (CLF) and outgoing long-wave radiation (OLR) over different climatic zones and land use/land cover types in South Asia during October 2004-December 2015. Simple linear regression shows that, over South Asia, tropo-NO2 variability is significantly linked to AOD, WS, NOx, Preci and CLF. Also zone-5, consisting of tropical monsoon areas of eastern India and Myanmar, is the only study zone over which all the selected parameters show their influence on tropo-NO2 at statistical significance levels. In stepwise multiple linear modeling, tropo-NO2 column over landmass of South Asia, is significantly predicted by the combination of RH (standardized regression coefficient, β = - 49), AOD (β = 0.42) and NOx (β = 0.25). The leading predictors of tropo-NO2 columns over zones 1-5 are OLR, AOD, Temp, OLR, and RH respectively. Overall, as revealed by the higher correlation coefficients (r), the multiple regressions provide reasonable models for tropo-NO2 over South Asia (r = 0.82), zone-4 (r = 0.90) and zone-5 (r = 0.93). The lowest r (of 0.66) has been found for hot semi-arid region in northwestern Indus-Ganges Basin (zone-2). The highest value of β for urban area AOD (of 0.42) is observed for megacity Lahore, located in warm semi-arid zone-2 with large scale crop-residue burning, indicating strong influence of aerosols on the modeled tropo-NO2 column. A statistical significant correlation (r = 0.22) at the 0.05 level is found between tropo-NO2 and AOD over Lahore. Also NOx emissions appear as the highest contributor (β = 0.59) for modeled tropo-NO2 column over megacity Dhaka.

  7. Global observations of tropospheric BrO columns using GOME-2 satellite data

    Science.gov (United States)

    Theys, N.; van Roozendael, M.; Hendrick, F.; Yang, X.; de Smedt, I.; Richter, A.; Begoin, M.; Errera, Q.; Johnston, P. V.; Kreher, K.; de Mazière, M.

    2011-02-01

    Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O3 and NO2 observations. Comparisons between the GOME-2 results and BrO vertical columns derived from correlative ground-based and SCIAMACHY nadir observations, present a good level of consistency. We show that the adopted technique enables separation of stratospheric and tropospheric fractions of the measured total BrO columns and allows quantitative study of the BrO plumes in polar regions. While some satellite observed plumes of enhanced BrO can be explained by stratospheric descending air, we show that most BrO hotspots are of tropospheric origin, although they are often associated to regions with low tropopause heights as well. Elaborating on simulations using the p-TOMCAT tropospheric chemical transport model, this result is found to be consistent with the mechanism of bromine release through sea salt aerosols production during blowing snow events. No definitive conclusion can be drawn however on the importance of blowing snow sources in comparison to other bromine release mechanisms. Outside polar regions, evidence is provided for a global tropospheric BrO background with column of 1-3 × 1013 molec cm-2, consistent with previous estimates.

  8. Global observations of tropospheric BrO columns using GOME-2 satellite data

    Directory of Open Access Journals (Sweden)

    N. Theys

    2011-02-01

    Full Text Available Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O3 and NO2 observations. Comparisons between the GOME-2 results and BrO vertical columns derived from correlative ground-based and SCIAMACHY nadir observations, present a good level of consistency. We show that the adopted technique enables separation of stratospheric and tropospheric fractions of the measured total BrO columns and allows quantitative study of the BrO plumes in polar regions. While some satellite observed plumes of enhanced BrO can be explained by stratospheric descending air, we show that most BrO hotspots are of tropospheric origin, although they are often associated to regions with low tropopause heights as well. Elaborating on simulations using the p-TOMCAT tropospheric chemical transport model, this result is found to be consistent with the mechanism of bromine release through sea salt aerosols production during blowing snow events. No definitive conclusion can be drawn however on the importance of blowing snow sources in comparison to other bromine release mechanisms. Outside polar regions, evidence is provided for a global tropospheric BrO background with column of 1–3 × 1013 molec cm2, consistent with previous estimates.

  9. Estimating Surface NO2 and SO2 Mixing Ratios from Fast-Response Total Column Observations and Potential Application to Geostationary Missions

    Science.gov (United States)

    Total-column nitrogen dioxide (NO2) data collected by a ground-based sun-tracking spectrometer system 21 (Pandora) and an photolytic-converter-based in-situ instrument collocated at NASA’s Langley Research Center in 22 Hampton, Virginia were analyzed to study the relationship bet...

  10. Estimation of Chinese surface NO2 concentrations combining satellite data and Land Use Regression

    Science.gov (United States)

    Anand, J.; Monks, P.

    2016-12-01

    Monitoring surface-level air quality is often limited by in-situ instrument placement and issues arising from harmonisation over long timescales. Satellite instruments can offer a synoptic view of regional pollution sources, but in many cases only a total or tropospheric column can be measured. In this work a new technique of estimating surface NO2 combining both satellite and in-situ data is presented, in which a Land Use Regression (LUR) model is used to create high resolution pollution maps based on known predictor variables such as population density, road networks, and land cover. By employing a mixed effects approach, it is possible to take advantage of the spatiotemporal variability in the satellite-derived column densities to account for daily and regional variations in surface NO2 caused by factors such as temperature, elevation, and wind advection. In this work, surface NO2 maps are modelled over the North China Plain and Pearl River Delta during high-pollution episodes by combining in-situ measurements and tropospheric columns from the Ozone Monitoring Instrument (OMI). The modelled concentrations show good agreement with in-situ data and surface NO2 concentrations derived from the MACC-II global reanalysis.

  11. Effects of Surface BRDF on the OMI Cloud and NO2 Retrievals: A New Approach Based on Geometry-Dependent Lambertian Equivalent Reflectivity (GLER) Derived from MODIS

    Science.gov (United States)

    Vasilkov, Alexander; Qin, Wenhan; Krotkov, Nickolay; Lamsal, Lok; Spurr, Robert; Haffner, David; Joiner, Joanna; Yang, Eun-Su; Marchenko, Sergey

    2017-01-01

    The Ozone Monitoring Instrument (OMI) cloud and NO2 algorithms use a monthly gridded surface reflectivity climatology that does not depend upon the observation geometry. In reality, reflection of incoming direct and diffuse solar light from land or ocean surfaces is sensitive to the sun sensor geometry. This dependence is described by the bidirectional reflectance distribution function (BRDF). To account for the BRDF, we propose to use a new concept of geometry-dependent Lambertian equivalent reflectivity (GLER). Implementation within the existing OMI cloud and NO2 retrieval infrastructure requires changes only to the input surface reflectivity database. GLER is calculated using a vector radiative transfer model with high spatial resolution BRDF information from MODIS over land and the Cox Munk slope distribution over ocean with a contribution from water-leaving radiance. We compare GLER and climatological LER at 466 nm, which is used in the OMI O2-O2cloud algorithm to derive effective cloud fractions. A detailed comparison of the cloud fractions and pressures derived with climatological and GLERs is carried out. GLER and corresponding retrieved cloud products are then used as input to the OMI NO2 algorithm. We find that replacing the climatological OMI-based LERs with GLERs can increase NO2 vertical columns by up to 50 % in highly polluted areas; the differences include both BRDF effects and biases between the MODIS and OMI-based surface reflectance data sets. Only minor changes to NO2 columns (within 5 %) are found over unpolluted and overcast areas.

  12. Using Satellite Remote Sensing and Modelling for Insights into N02 Air Pollution and NO2 Emissions

    Science.gov (United States)

    Lamsal, L. N.; Martin, R. V.; Krotkov, N. A.; Bucsela, E. J.; Celarier, E. A.; vanDonkelaar, A.; Parrish, D.

    2012-01-01

    Nitrogen oxides (NO(x)) are key actors in air quality and climate change. Satellite remote sensing of tropospheric NO2 has developed rapidly with enhanced spatial and temporal resolution since initial observations in 1995. We have developed an improved algorithm and retrieved tropospheric NO2 columns from Ozone Monitoring Instrument. Column observations of tropospheric NO2 from the nadir-viewing satellite sensors contain large contributions from the boundary layer due to strong enhancement of NO2 in the boundary layer. We infer ground-level NO2 concentrations from the OMI satellite instrument which demonstrate significant agreement with in-situ surface measurements. We examine how NO2 columns measured by satellite, ground-level NO2 derived from satellite, and NO(x) emissions obtained from bottom-up inventories relate to world's urban population. We perform inverse modeling analysis of NO2 measurements from OMI to estimate "top-down" surface NO(x) emissions, which are used to evaluate and improve "bottom-up" emission inventories. We use NO2 column observations from OMI and the relationship between NO2 columns and NO(x) emissions from a GEOS-Chem model simulation to estimate the annual change in bottom-up NO(x) emissions. The emission updates offer an improved estimate of NO(x) that are critical to our understanding of air quality, acid deposition, and climate change.

  13. Impact of NO2 Profile Shape in OMI Tropospheric NO2 Retrievals

    Science.gov (United States)

    Lamsal, Lok; Krotkov, Nickolay A.; Pickering, K.; Schwartz, W. H.; Celarier, E. A.; Bucsela, E. J.; Gleason, J. F.; Philip, S.; Nowlan, C.; Martin, R. V.; hide

    2013-01-01

    Nitrogen oxides (NOx NO + NO2) are key actors in air quality and climate change. Tropospheric NO2 columns from the nadir-viewing satellite sensors have been widely used to understand sources and chemistry of NOx. We have implemented several improvements to the operational algorithm developed at NASA GSFC and retrieved tropospheric NO2 columns. We present tropospheric NO2 validation studies of the new OMI Standard Product version 2.1 using ground-based and in-situ aircraft measurements. We show how vertical profile of scattering weight and a-priori NO2 profile shapes, which are taken from chemistry-transport models, affect air mass factor (AMF) and therefore tropospheric NO2 retrievals. Users can take advantage of scattering weights information that is made available in the operational NO2 product. Improved tropospheric NO2 data retrieved using thoroughly evaluated high spatial resolution NO2 profiles are helpful to test models.

  14. Distillation Column Flooding Predictor

    Energy Technology Data Exchange (ETDEWEB)

    George E. Dzyacky

    2010-11-23

    The Flooding Predictor™ is a patented advanced control technology proven in research at the Separations Research Program, University of Texas at Austin, to increase distillation column throughput by over 6%, while also increasing energy efficiency by 10%. The research was conducted under a U. S. Department of Energy Cooperative Agreement awarded to George Dzyacky of 2ndpoint, LLC. The Flooding Predictor™ works by detecting the incipient flood point and controlling the column closer to its actual hydraulic limit than historical practices have allowed. Further, the technology uses existing column instrumentation, meaning no additional refining infrastructure is required. Refiners often push distillation columns to maximize throughput, improve separation, or simply to achieve day-to-day optimization. Attempting to achieve such operating objectives is a tricky undertaking that can result in flooding. Operators and advanced control strategies alike rely on the conventional use of delta-pressure instrumentation to approximate the column’s approach to flood. But column delta-pressure is more an inference of the column’s approach to flood than it is an actual measurement of it. As a consequence, delta pressure limits are established conservatively in order to operate in a regime where the column is never expected to flood. As a result, there is much “left on the table” when operating in such a regime, i.e. the capacity difference between controlling the column to an upper delta-pressure limit and controlling it to the actual hydraulic limit. The Flooding Predictor™, an innovative pattern recognition technology, controls columns at their actual hydraulic limit, which research shows leads to a throughput increase of over 6%. Controlling closer to the hydraulic limit also permits operation in a sweet spot of increased energy-efficiency. In this region of increased column loading, the Flooding Predictor is able to exploit the benefits of higher liquid

  15. Relationship between synoptic scale weather systems and column averaged atmospheric CO2

    Science.gov (United States)

    Naja, M.; Yaremchuk, A.; Onishi, R.; Maksyutov, S.; Inoue, G.

    2005-12-01

    Analysis of the atmospheric CO2 observations with transport models contributes to the understanding of the geographical distributions of CO2 sources and sinks. Space-borne sensors could be advantageous for CO2 measurements as they can provide wider spatial and temporal coverage. Inversion studies have suggested requirement of better than 1% precision for the space-borne observations. Since sources and sinks are inferred from spatial and temporal gradients in CO2, the space-borne observations must have no significant geographically varying biases. To study the dynamical biases in column CO2 due to possible correlation between clouds and atmospheric CO2 at synoptic scale, we have made simulations of CO2 (1988-2003) using NIES tracer transport model. Model resolution is 2.5o x 2.5o in horizontal and it has 15 vertical sigma-layers. Fluxes for (1) fossil fuels, (2) terrestrial biosphere (CASA NEP), (3) the oceans, and (4) inverse model derived monthly regional fluxes from 11 land and 11 ocean regions are used. SVD truncation is used to filter out noise in the inverse model flux time series. Model reproduces fairly well CO2 global trend and observed time series at monitoring sites around the globe. Lower column CO2 concentration is simulated inside cyclonic systems in summer over North hemispheric continental areas. Surface pressure is used as a proxy for dynamics and it is demonstrated that anomalies in column averaged CO2 has fairly good correlation with the anomalies in surface pressure. Positive correlation, as high as 0.7, has been estimated over parts of Siberia and N. America in summer time. Our explanation is based on that the low-pressure system is associated the upward motion, which leads to lower column CO2 values over these regions due to lifting of CO2-depleted summertime PBL air, and higher column CO2 over source areas. A sensitivity study without inverse model fluxes shows same correlation. The low-pressure systems' induced negative biases are 0

  16. Derivation of basic equations for rigorous dynamic simulation of cryogenic distillation column for hydrogen isotope separation

    International Nuclear Information System (INIS)

    Kinoshita, Masahiro; Naruse, Yuji

    1981-08-01

    The basic equations are derived for rigorous dynamic simulation of cryogenic distillation columns for hydrogen isotope separation. The model accounts for such factors as differences in latent heat of vaporization among the six isotopic species of molecular hydrogen, decay heat of tritium, heat transfer through the column wall and nonideality of the solutions. Provision is also made for simulation of columns with multiple feeds and multiple sidestreams. (author)

  17. Relationship Between Column-Density and Surface Mixing Ratio: Statistical Analysis of O3 and NO2 Data from the July 2011 Maryland DISCOVER-AQ Mission

    Science.gov (United States)

    Flynn, Clare; Pickering, Kenneth E.; Crawford, James H.; Lamsol, Lok; Krotkov, Nickolay; Herman, Jay; Weinheimer, Andrew; Chen, Gao; Liu, Xiong; Szykman, James; hide

    2014-01-01

    To investigate the ability of column (or partial column) information to represent surface air quality, results of linear regression analyses between surface mixing ratio data and column abundances for O3 and NO2 are presented for the July 2011 Maryland deployment of the DISCOVER-AQ mission. Data collected by the P-3B aircraft, ground-based Pandora spectrometers, Aura/OMI satellite instrument, and simulations for July 2011 from the CMAQ air quality model during this deployment provide a large and varied data set, allowing this problem to be approached from multiple perspectives. O3 columns typically exhibited a statistically significant and high degree of correlation with surface data (R(sup 2) > 0.64) in the P- 3B data set, a moderate degree of correlation (0.16 analysis.

  18. Retrieval of tropospheric NO2 using the MAX-DOAS method combined with relative intensity measurements for aerosol correction

    Directory of Open Access Journals (Sweden)

    P. F. Levelt

    2010-10-01

    Full Text Available Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS is a technique to measure trace gas amounts in the lower troposphere from ground-based scattered sunlight observations. MAX-DOAS observations are especially suitable for validation of tropospheric trace gas observations from satellite, since they have a representative range of several kilometers, both in the horizontal and in the vertical dimension. A two-step retrieval scheme is presented here, to derive aerosol corrected tropospheric NO2 columns from MAX-DOAS observations. In a first step, boundary layer aerosols, characterized in terms of aerosol optical thickness (AOT, are estimated from relative intensity observations, which are defined as the ratio of the sky radiance at elevation α and the sky radiance in the zenith. Relative intensity measurements have the advantage of a strong dependence on boundary layer AOT and almost no dependence on boundary layer height. In a second step, tropospheric NO2 columns are derived from differential slant columns, based on AOT-dependent air mass factors. This two-step retrieval scheme was applied to cloud free periods in a twelve month data set of observations in De Bilt, The Netherlands. In a comparison with AERONET (Cabauw site a mean difference in AOT (AERONET minus MAX-DOAS of −0.01±0.08 was found, and a correlation of 0.85. Tropospheric-NO2 columns were compared with OMI-satellite tropospheric NO2. For ground-based observations restricted to uncertainties below 10%, no significant difference was found, and a correlation of 0.88.

  19. Biodegradation of No. 2 diesel fuel in the vadose zone: A soil column study

    International Nuclear Information System (INIS)

    Widrig, D.L.; Manning, J.F. Jr.

    1995-01-01

    Packed soil columns were used to simulate and investigate in situ biological remediation of soil contaminated with diesel fuel. The authors investigated and evaluated several operating strategies, including continuous flooding of the column soil with nutrient solution, and periodic operating cycles consisting of flooding followed by draining and aeration. The objectives were: (a) to determine the extent of diesel fuel degradation in soil columns under four operating conditions (biologically inhibited control; continuous saturation with nitrogen and phosphorus amendments; periodic operation, consisting of flooding with nitrogen and phosphorus, followed by draining and forced aeration; and periodic operation, consisting of flooding with nitrogen phosphorus, and calcium and magnesium amendments, followed by draining and forced aeration); (b) to evaluate CO 2 production and oxygen consumption as indicators of biodegradation; (c) to monitor hydraulic conductivity under different operating strategies; and (d) to examine the system requirements for nitrogen and phosphorus. The results showed that periodic operation promoted higher rates of biodegradation of diesel fuel in soil and minimized the use of water containing nutrient amendments, and consequently the possible need to collect and treat such water. The authors believe that monitoring CO 2 and O 2 levels in situ may provide a means of optimizing the timing of flooding and aeration events to increase degradation rates. Results of this laboratory study will aid in improving the design and operation of field-scale bioremediation systems

  20. Column-to-column packing variation of disposable pre-packed columns for protein chromatography.

    Science.gov (United States)

    Schweiger, Susanne; Hinterberger, Stephan; Jungbauer, Alois

    2017-12-08

    In the biopharmaceutical industry, pre-packed columns are the standard for process development, but they must be qualified before use in experimental studies to confirm the required performance of the packed bed. Column qualification is commonly done by pulse response experiments and depends highly on the experimental testing conditions. Additionally, the peak analysis method, the variation in the 3D packing structure of the bed, and the measurement precision of the workstation influence the outcome of qualification runs. While a full body of literature on these factors is available for HPLC columns, no comparable studies exist for preparative columns for protein chromatography. We quantified the influence of these parameters for commercially available pre-packed and self-packed columns of disposable and non-disposable design. Pulse response experiments were performed on 105 preparative chromatography columns with volumes of 0.2-20ml. The analyte acetone was studied at six different superficial velocities (30, 60, 100, 150, 250 and 500cm/h). The column-to-column packing variation between disposable pre-packed columns of different diameter-length combinations varied by 10-15%, which was acceptable for the intended use. The column-to-column variation cannot be explained by the packing density, but is interpreted as a difference in particle arrangement in the column. Since it was possible to determine differences in the column-to-column performance, we concluded that the columns were well-packed. The measurement precision of the chromatography workstation was independent of the column volume and was in a range of±0.01ml for the first peak moment and±0.007 ml 2 for the second moment. The measurement precision must be considered for small columns in the range of 2ml or less. The efficiency of disposable pre-packed columns was equal or better than that of self-packed columns. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  1. Two generalizations of column-convex polygons

    International Nuclear Information System (INIS)

    Feretic, Svjetlan; Guttmann, Anthony J

    2009-01-01

    Column-convex polygons were first counted by area several decades ago, and the result was found to be a simple, rational, generating function. In this work we generalize that result. Let a p-column polyomino be a polyomino whose columns can have 1, 2, ..., p connected components. Then column-convex polygons are equivalent to 1-convex polyominoes. The area generating function of even the simplest generalization, namely 2-column polyominoes, is unlikely to be solvable. We therefore define two classes of polyominoes which interpolate between column-convex polygons and 2-column polyominoes. We derive the area generating functions of those two classes, using extensions of existing algorithms. The growth constants of both classes are greater than the growth constant of column-convex polyominoes. Rather tight lower bounds on the growth constants complement a comprehensive asymptotic analysis.

  2. OMI Satellite and Ground-Based Pandora Observations and Their Application to Surface NO2 Estimations at Terrestrial and Marine Sites

    Science.gov (United States)

    Kollonige, Debra E.; Thompson, Anne M.; Josipovic, Miroslav; Tzortziou, Maria; Beukes, Johan P.; Burger, Roelof; Martins, Douglas K.; van Zyl, Pieter G.; Vakkari, Ville; Laakso, Lauri

    2018-01-01

    The Pandora spectrometer that uses direct-Sun measurements to derive total column amounts of gases provides an approach for (1) validation of satellite instruments and (2) monitoring of total column (TC) ozone (O3) and nitrogen dioxide (NO2). We use for the first time Pandora and Ozone Monitoring Instrument (OMI) observations to estimate surface NO2 over marine and terrestrial sites downwind of urban pollution and compared with in situ measurements during campaigns in contrasting regions: (1) the South African Highveld (at Welgegund, 26°34'10″S, 26°56'21″E, 1,480 m asl, 120 km southwest of the Johannesburg-Pretoria megacity) and (2) shipboard U.S. mid-Atlantic coast during the 2014 Deposition of Atmospheric Nitrogen to Coastal Ecosystems (DANCE) cruise. In both cases, there were no local NOx sources but intermittent regional pollution influences. For TC NO2, OMI and Pandora difference is 20%, with Pandora higher most times. Surface NO2 values estimated from OMI and Pandora columns are compared to in situ NO2 for both locations. For Welgegund, the planetary boundary layer (PBL) height, used in converting column to surface NO2 value, has been estimated by three methods: co-located Atmospheric Infrared Sounder (AIRS) observations; a model simulation; and radiosonde data from Irene, 150 km northeast of the site. AIRS PBL heights agree within 10% of radiosonde-derived values. Absolute differences between Pandora- and OMI-estimated surface NO2 and the in situ data are better at the terrestrial site ( 0.5 ppbv and 1 ppbv or greater, respectively) than under clean marine air conditions, with differences usually >3 ppbv. Cloud cover and PBL variability influence these estimations.

  3. A high-resolution and observationally constrained OMI NO2 satellite retrieval

    International Nuclear Information System (INIS)

    Goldberg, Daniel L.; Lamsal, Lok N.; Loughner, Christopher P.

    2017-01-01

    Here, this work presents a new high-resolution NO 2 dataset derived from the NASA Ozone Monitoring Instrument (OMI) NO 2 version 3.0 retrieval that can be used to estimate surface-level concentrations. The standard NASA product uses NO 2 vertical profile shape factors from a 1.25° × 1° (~110 km × 110 km) resolution Global Model Initiative (GMI) model simulation to calculate air mass factors, a critical value used to determine observed tropospheric NO 2 vertical columns. To better estimate vertical profile shape factors, we use a high-resolution (1.33 km × 1.33 km) Community Multi-scale Air Quality (CMAQ) model simulation constrained by in situ aircraft observations to recalculate tropospheric air mass factors and tropospheric NO 2 vertical columns during summertime in the eastern US. In this new product, OMI NO 2 tropospheric columns increase by up to 160% in city centers and decrease by 20–50 % in the rural areas outside of urban areas when compared to the operational NASA product. Our new product shows much better agreement with the Pandora NO 2 and Airborne Compact Atmospheric Mapper (ACAM) NO 2 spectrometer measurements acquired during the DISCOVER-AQ Maryland field campaign. Furthermore, the correlation between our satellite product and EPA NO 2 monitors in urban areas has improved dramatically: r 2 = 0.60 in the new product vs. r 2 = 0.39 in the operational product, signifying that this new product is a better indicator of surface concentrations than the operational product. Our work emphasizes the need to use both high-resolution and high-fidelity models in order to recalculate satellite data in areas with large spatial heterogeneities in NO x emissions. Although the current work is focused on the eastern US, the methodology developed in this work can be applied to other world regions to produce high-quality region-specific NO 2 satellite retrievals.

  4. Properties of the Water Column and Bottom Derived from AVIRIS Data

    Science.gov (United States)

    Lee, Zhong-Ping; Carder, Kendall L.; Chen, F. Robert; Peacock, Thomas G.

    2001-01-01

    Using AVIRIS data as an example, we show in this study that the optical properties of the water column and bottom of a large, shallow area can be adequately retrieved using a model-driven optimization technique. The simultaneously derived properties include bottom depth, bottom albedo, and water absorption and backscattering coefficients, which in turn could be used to derive concentrations of chlorophyll, dissolved organic matter, and suspended sediments. The derived bottom depths were compared with a bathymetry chart and a boat survey and were found to agree very well. Also, the derived bottom-albedo image shows clear spatial patterns, with end members consistent with sand and seagrass. The image of absorption and backscattering coefficients indicates that the water is quite horizontally mixed. These results suggest that the model and approach used work very well for the retrieval of sub-surface properties of shallow-water environments even for rather turbid environments like Tampa Bay, Florida.

  5. A stochastic view on column efficiency.

    Science.gov (United States)

    Gritti, Fabrice

    2018-03-09

    A stochastic model of transcolumn eddy dispersion along packed beds was derived. It was based on the calculation of the mean travel time of a single analyte molecule from one radial position to another. The exchange mechanism between two radial positions was governed by the transverse dispersion of the analyte across the column. The radial velocity distribution was obtained by flow simulations in a focused-ion-beam scanning electron microscopy (FIB-SEM) based 3D reconstruction from a 2.1 mm × 50 mm column packed with 2 μm BEH-C 18 particles. Accordingly, the packed bed was divided into three coaxial and uniform zones: (1) a 1.4 particle diameter wide, ordered, and loose packing at the column wall (velocity u w ), (2) an intermediate 130 μm wide, random, and dense packing (velocity u i ), and (3) the bulk packing in the center of the column (velocity u c ). First, the validity of this proposed stochastic model was tested by adjusting the predicted to the observed reduced van Deemter plots of a 2.1 mm × 50 mm column packed with 2 μm BEH-C 18 fully porous particles (FPPs). An excellent agreement was found for u i  = 0.93u c , a result fully consistent with the FIB-SEM observation (u i  = 0.95u c ). Next, the model was used to measure u i  = 0.94u c for 2.1 mm × 100 mm column packed with 1.6 μm Cortecs-C 18 superficially porous particles (SPPs). The relative velocity bias across columns packed with SPPs is then barely smaller than that observed in columns packed with FPPs (+6% versus + 7%). u w =1.8u i is measured for a 75 μm × 1 m capillary column packed with 2 μm BEH-C 18 particles. Despite this large wall-to-center velocity bias (+80%), the presence of the thin and ordered wall packing layer has no negative impact on the kinetic performance of capillary columns. Finally, the stochastic model of long-range eddy dispersion explains why analytical (2.1-4.6 mm i.d.) and capillary (columns can all be

  6. Eleven years of tropospheric NO2 measured by GOME, SCIAMACHY and OMI

    Science.gov (United States)

    Eskes, H.; Boersma, F.; Dirksen, R.; van der A, R.; Veefkind, P.; Levelt, P.; Brinksma, E.; van Roozendael, M.; de Smedt, I.; Gleason, J.

    2006-12-01

    Based on measurements of GOME on ESA ERS-2, SCIAMACHY on ESA-ENVISAT, and Ozone Monitoring Instrument (OMI) on the NASA EOS-Aura satellite there is now a unique 11-year dataset of global tropospheric nitrogen dioxide measurements from space. The retrieval approach consists of two steps. The first step is an application of the DOAS (Differential Optical Absorption Spectroscopy) approach which delivers the total absorption optical thickness along the light path (the slant column). For GOME and SCIAMACHY this is based on the DOAS implementation developed by BIRA/IASB. For OMI the DOAS implementation was developed in a collaboration between KNMI and NASA. The second retrieval step, developed at KNMI, estimates the tropospheric vertical column of NO2 based on the slant column, cloud fraction and cloud top height retrieval, stratospheric column estimates derived from a data assimilation approach and vertical profile estimates from space-time collocated profiles from the TM chemistry-transport model. The second step was applied with only minor modifications to all three instruments to generate a uniform 11-year data set. In our talk we will address the following topics: - A short summary of the retrieval approach and results - Comparisons with other retrievals - Comparisons with global and regional-scale models - OMI-SCIAMACHY and SCIAMACHY-GOME comparisons - Validation with independent measurements - Trend studies of NO2 for the past 11 years

  7. The Next-generation Berkeley High Resolution NO2 (BEHR NO2) Retrieval: Design and Preliminary Emissions Constraints

    Science.gov (United States)

    Laughner, J.; Cohen, R. C.

    2017-12-01

    Recent work has identified a number of assumptions made in NO2 retrievals that lead to biases in the retrieved NO2 column density. These include the treatment of the surface as an isotropic reflector, the absence of lightning NO2 in high resolution a priori profiles, and the use of monthly averaged a priori profiles. We present a new release of the Berkeley High Resolution (BEHR) OMI NO2 retrieval based on the new NASA Standard Product (version 3) that addresses these assumptions by: accounting for surface anisotropy by using a BRDF albedo product, using an updated method of regridding NO2 data, and revised NO2 a priori profiles that better account for lightning NO2 and daily variation in the profile shape. We quantify the effect these changes have on the retrieved NO2 column densities and the resultant impact these updates have on constraints of urban NOx emissions for select cities throughout the United States.

  8. TRACING H2 COLUMN DENSITY WITH ATOMIC CARBON (C I) AND CO ISOTOPOLOGS

    International Nuclear Information System (INIS)

    Lo, N.; Bronfman, L.; Cunningham, M. R.; Jones, P. A.; Lowe, V.; Cortes, P. C.; Simon, R.; Fissel, L.; Novak, G.

    2014-01-01

    We present the first results of neutral carbon ([C I] 3 P 1 - 3 P 0 at 492 GHz) and carbon monoxide ( 13 CO, J = 1-0) mapping in the Vela Molecular Ridge cloud C (VMR-C) and the G333 giant molecular cloud complexes with the NANTEN2 and Mopra telescopes. For the four regions mapped in this work, we find that [C I] has very similar spectral emission profiles to 13 CO, with comparable line widths. We find that [C I] has an opacity of 0.1-1.3 across the mapped region while the [C I]/ 13 CO peak brightness temperature ratio is between 0.2 and 0.8. The [C I] column density is an order of magnitude lower than that of 13 CO. The H 2 column density derived from [C I] is comparable to values obtained from 12 CO. Our maps show that C I is preferentially detected in gas with low temperatures (below 20 K), which possibly explains the comparable H 2 column density calculated from both tracers (both C I and 12 CO underestimate column density), as a significant amount of the C I in the warmer gas is likely in the higher energy state transition ([C I] 3 P 2 - 3 P 1 at 810 GHz), and thus it is likely that observations of both the above [C I] transitions are needed in order to recover the total H 2 column density

  9. Global CO2 fluxes estimated from GOSAT retrievals of total column CO2

    Directory of Open Access Journals (Sweden)

    S. Basu

    2013-09-01

    Full Text Available We present one of the first estimates of the global distribution of CO2 surface fluxes using total column CO2 measurements retrieved by the SRON-KIT RemoTeC algorithm from the Greenhouse gases Observing SATellite (GOSAT. We derive optimized fluxes from June 2009 to December 2010. We estimate fluxes from surface CO2 measurements to use as baselines for comparing GOSAT data-derived fluxes. Assimilating only GOSAT data, we can reproduce the observed CO2 time series at surface and TCCON sites in the tropics and the northern extra-tropics. In contrast, in the southern extra-tropics GOSAT XCO2 leads to enhanced seasonal cycle amplitudes compared to independent measurements, and we identify it as the result of a land–sea bias in our GOSAT XCO2 retrievals. A bias correction in the form of a global offset between GOSAT land and sea pixels in a joint inversion of satellite and surface measurements of CO2 yields plausible global flux estimates which are more tightly constrained than in an inversion using surface CO2 data alone. We show that assimilating the bias-corrected GOSAT data on top of surface CO2 data (a reduces the estimated global land sink of CO2, and (b shifts the terrestrial net uptake of carbon from the tropics to the extra-tropics. It is concluded that while GOSAT total column CO2 provide useful constraints for source–sink inversions, small spatiotemporal biases – beyond what can be detected using current validation techniques – have serious consequences for optimized fluxes, even aggregated over continental scales.

  10. Optimization and simulation of tandem column supercritical fluid chromatography separations using column back pressure as a unique parameter.

    Science.gov (United States)

    Wang, Chunlei; Tymiak, Adrienne A; Zhang, Yingru

    2014-04-15

    Tandem column supercritical fluid chromatography (SFC) has demonstrated to be a useful technique to resolve complex mixtures by serially coupling two columns of different selectivity. The overall selectivity of a tandem column separation is the retention time weighted average of selectivity from each coupled column. Currently, the method development merely relies on extensive screenings and is often a hit-or-miss process. No attention is paid to independently adjust retention and selectivity contributions from individual columns. In this study, we show how tandem column SFC selectivity can be optimized by changing relative dimensions (length or inner diameter) of the coupled columns. Moreover, we apply column back pressure as a unique parameter for SFC optimization. Continuous tuning of tandem column SFC selectivity is illustrated through column back pressure adjustments of the upstream column, for the first time. In addition, we show how and why changing coupling order of the columns can produce dramatically different separations. Using the empirical mathematical equation derived in our previous study, we also demonstrate a simulation of tandem column separations based on a single retention time measurement on each column. The simulation compares well with experimental results and correctly predicts column order and back pressure effects on the separations. Finally, considerations on instrument and column hardware requirements are discussed.

  11. Investigations of temporal and spatial distribution of precursors SO2 and NO2 vertical columns in the North China Plain using mobile DOAS

    Science.gov (United States)

    Wu, Fengcheng; Xie, Pinhua; Li, Ang; Mou, Fusheng; Chen, Hao; Zhu, Yi; Zhu, Tong; Liu, Jianguo; Liu, Wenqing

    2018-02-01

    Recently, Chinese cities have suffered severe events of haze air pollution, particularly in the North China Plain (NCP). Investigating the temporal and spatial distribution of pollutants, emissions, and pollution transport is necessary to better understand the effect of various sources on air quality. We report on mobile differential optical absorption spectroscopy (mobile DOAS) observations of precursors SO2 and NO2 vertical columns in the NCP in the summer of 2013 (from 11 June to 7 July) in this study. The different temporal and spatial distributions of SO2 and NO2 vertical column density (VCD) over this area are characterized under various wind fields. The results show that transport from the southern NCP strongly affects air quality in Beijing, and the transport route, particularly SO2 transport on the route of Shijiazhuang-Baoding-Beijing, is identified. In addition, the major contributors to SO2 along the route of Shijiazhuang-Baoding-Beijing are elevated sources compared to low area sources for the route of Dezhou-Cangzhou-Tianjin-Beijing; this is found using the interrelated analysis between in situ and mobile DOAS observations during the measurement periods. Furthermore, the discussions on hot spots near the city of JiNan show that average observed width of polluted air mass is 11.83 and 17.23 km associated with air mass diffusion, which is approximately 60 km away from emission sources based on geometrical estimation. Finally, a reasonable agreement exists between the Ozone Monitoring Instrument (OMI) and mobile DOAS observations, with a correlation coefficient (R2) of 0.65 for NO2 VCDs. Both datasets also have a similar spatial pattern. The fitted slope of 0.55 is significantly less than unity, which can reflect the contamination of local sources, and OMI observations are needed to improve the sensitivities to the near-surface emission sources through improvements of the retrieval algorithm or the resolution of satellites.

  12. NOx retention in scrubbing column

    International Nuclear Information System (INIS)

    Nakazone, A.K.; Costa, R.E.; Lobao, A.S.T.; Matsuda, H.T.; Araujo, B.F.

    1988-07-01

    During the UO 2 dissolution in nitric acid, some different species of NO x are released. The off gas can either be refluxed to the dissolver or be released and retained on special columns. The final composition of the solution is the main parameter to take in account. A process for nitrous gases retention using scubber columns containing H 2 O or diluted HNO 3 is presented. Chemiluminescence measurement was employed to NO x evalution before and after scrubbing. Gas flow, temperature, residence time are the main parameters considered in this paper. For the dissolution of 100g UO 2 in 8M nitric acid, a 6NL/h O 2 flow was the best condition for the NO/NO 2 oxidation with maximum adsorption in the scrubber columns. (author) [pt

  13. ( Anogeissus leiocarpus ) timber columns

    African Journals Online (AJOL)

    A procedure for designing axially loaded Ayin (Anogeissus leiocarpus) wood column or strut has been investigated. Instead of the usual categorization of columns into short, intermediate and slender according to the value of slenderness ratio, a continuous column formula representing the three categories was derived.

  14. Comparison of Surface and Column Variations of CO2 Over Urban Areas for Future Active Remote CO2 Sensors

    Science.gov (United States)

    Choi, Yonghoon; Yang, Melissa; Kooi, Susan; Browell, Edward

    2015-01-01

    High resolution in-situ CO2 measurements were recorded onboard the NASA P-3B during the DISCOVER-AQ (Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality) Field Campaign, to investigate the ability of space-based observations to accurately assess near surface conditions related to air quality. This campaign includes, Washington DC/Baltimore, MD (July 2011), San Joaquin Valley, CA (January - February 2013), Houston, TX (September 2013), and Denver, CO (July-August 2014). Each of these campaigns consisted of missed approaches and approximately two hundred vertical soundings of CO2 within the lower troposphere (surface to about 5 km). In this study, surface (0 - 1 km) and column-averaged (0 - 3.5 km) CO2 mixing ratio values from the vertical soundings in the four geographically different urban areas are used to investigate the temporal and spatial variability of CO2 within the different urban atmospheric emission environments. Tracers such as CO, CH2O, NOx, and NMHCs are used to identify the source of CO2 variations in the urban sites. Additionally, we apply nominal CO2 column weighting functions for potential future active remote CO2 sensors operating in the 1.57-microns and 2.05-microns measurement regions to convert the in situ CO2 vertical mixing ratio profiles to variations in CO2 column optical depths, which is what the active remote sensors actually measure. Using statistics calculated from the optical depths at each urban site measured during the DISCOVER-AQ field campaign and for each nominal weighting function, we investigate the natural variability of CO2 columns in the lower troposphere; relate the CO2 column variability to the urban surface emissions; and show the measurement requirements for the future ASCENDS (Active Sensing of CO2 Emissions over Nights, Days, and Seasons) in the continental U.S. urban areas.

  15. Atmospheric CO2 Column Measurements with an Airborne Intensity-Modulated Continuous-Wave 1.57-micron Fiber Laser Lidar

    Science.gov (United States)

    Dobler, Jeremy T.; Harrison, F. Wallace; Browell, Edward V.; Lin, Bing; McGregor, Doug; Kooi, Susan; Choi, Yonghoon; Ismail, Syed

    2013-01-01

    The 2007 National Research Council (NRC) Decadal Survey on Earth Science and Applications from Space recommended Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) as a mid-term, Tier II, NASA space mission. ITT Exelis, formerly ITT Corp., and NASA Langley Research Center have been working together since 2004 to develop and demonstrate a prototype Laser Absorption Spectrometer for making high-precision, column CO2 mixing ratio measurements needed for the ASCENDS mission. This instrument, called the Multifunctional Fiber Laser Lidar (MFLL), operates in an intensity-modulated, continuous-wave mode in the 1.57- micron CO2 absorption band. Flight experiments have been conducted with the MFLL on a Lear-25, UC-12, and DC-8 aircraft over a variety of different surfaces and under a wide range of atmospheric conditions. Very high-precision CO2 column measurements resulting from high signal-to-noise (great than 1300) column optical depth measurements for a 10-s (approximately 1 km) averaging interval have been achieved. In situ measurements of atmospheric CO2 profiles were used to derive the expected CO2 column values, and when compared to the MFLL measurements over desert and vegetated surfaces, the MFLL measurements were found to agree with the in situ-derived CO2 columns to within an average of 0.17% or approximately 0.65 ppmv with a standard deviation of 0.44% or approximately 1.7 ppmv. Initial results demonstrating ranging capability using a swept modulation technique are also presented.

  16. 4SM: A Novel Self-Calibrated Algebraic Ratio Method for Satellite-Derived Bathymetry and Water Column Correction

    Directory of Open Access Journals (Sweden)

    Yann G. Morel

    2017-07-01

    Full Text Available All empirical water column correction methods have consistently been reported to require existing depth sounding data for the purpose of calibrating a simple depth retrieval model; they yield poor results over very bright or very dark bottoms. In contrast, we set out to (i use only the relative radiance data in the image along with published data, and several new assumptions; (ii in order to specify and operate the simplified radiative transfer equation (RTE; (iii for the purpose of retrieving both the satellite derived bathymetry (SDB and the water column corrected spectral reflectance over shallow seabeds. Sea truth regressions show that SDB depths retrieved by the method only need tide correction. Therefore it shall be demonstrated that, under such new assumptions, there is no need for (i formal atmospheric correction; (ii conversion of relative radiance into calibrated reflectance; or (iii existing depth sounding data, to specify the simplified RTE and produce both SDB and spectral water column corrected radiance ready for bottom typing. Moreover, the use of the panchromatic band for that purpose is introduced. Altogether, we named this process the Self-Calibrated Supervised Spectral Shallow-sea Modeler (4SM. This approach requires a trained practitioner, though, to produce its results within hours of downloading the raw image. The ideal raw image should be a “near-nadir” view, exhibit homogeneous atmosphere and water column, include some coverage of optically deep waters and bare land, and lend itself to quality removal of haze, atmospheric adjacency effect, and sun/sky glint.

  17. 4SM: A Novel Self-Calibrated Algebraic Ratio Method for Satellite-Derived Bathymetry and Water Column Correction.

    Science.gov (United States)

    Morel, Yann G; Favoretto, Fabio

    2017-07-21

    All empirical water column correction methods have consistently been reported to require existing depth sounding data for the purpose of calibrating a simple depth retrieval model; they yield poor results over very bright or very dark bottoms. In contrast, we set out to (i) use only the relative radiance data in the image along with published data, and several new assumptions; (ii) in order to specify and operate the simplified radiative transfer equation (RTE); (iii) for the purpose of retrieving both the satellite derived bathymetry (SDB) and the water column corrected spectral reflectance over shallow seabeds. Sea truth regressions show that SDB depths retrieved by the method only need tide correction. Therefore it shall be demonstrated that, under such new assumptions, there is no need for (i) formal atmospheric correction; (ii) conversion of relative radiance into calibrated reflectance; or (iii) existing depth sounding data, to specify the simplified RTE and produce both SDB and spectral water column corrected radiance ready for bottom typing. Moreover, the use of the panchromatic band for that purpose is introduced. Altogether, we named this process the Self-Calibrated Supervised Spectral Shallow-sea Modeler (4SM). This approach requires a trained practitioner, though, to produce its results within hours of downloading the raw image. The ideal raw image should be a "near-nadir" view, exhibit homogeneous atmosphere and water column, include some coverage of optically deep waters and bare land, and lend itself to quality removal of haze, atmospheric adjacency effect, and sun/sky glint.

  18. Properties of the water column and bottom derived from Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data

    Science.gov (United States)

    Lee, Zhongping; Carder, Kendall L.; Chen, Robert F.; Peacock, Thomas G.

    2001-06-01

    Using Airborne Visible Infrared Imaging Spectrometer (AVIRIS) data as an example, we show in this study that the properties of the water column and bottom of a large, shallow area can be adequately retrieved using a model-driven optimization technique. The simultaneously derived properties include bottom depth, bottom albedo, and water absorption and backscattering coefficients, which in turn could be used to derive concentrations of chlorophyll, dissolved organic matter, and suspended sediments in the water column. The derived bottom depths were compared with a bathymetry chart and a boat survey and were found to agree very well. Also, the derived bottom albedo image shows clear spatial patterns, with end-members consistent with sand and seagrass. The image of absorption and backscattering coefficients indicates that the water is quite horizontally mixed. Without bottom corrections, chlorophyll a retrievals were ˜50 mg m-3, while the retrievals after bottom corrections were tenfold less, approximating real values. These results suggest that the model and approach used work very well for the retrieval of subsurface properties of shallow-water environments even for rather turbid environments like Tampa Bay, Florida.

  19. Limb-Nadir Matching Using Non-Coincident NO2 Observations: Proof of Concept and the OMI-minus-OSIRIS Prototype Product

    Science.gov (United States)

    Adams, Cristen; Normand, Elise N.; Mclinden, Chris A.; Bourassa, Adam E.; Lloyd, Nicholas D.; Degenstein, Douglas A.; Krotkov, Nickolay A.; Rivas, Maria Belmonte; Boersma, K. Folkert; Eskes, Henk

    2016-01-01

    A variant of the limb-nadir matching technique for deriving tropospheric NO2 columns is presented in which the stratospheric component of the NO2 slant column density (SCD) measured by the Ozone Monitoring Instrument (OMI) is removed using non-coincident profiles from the Optical Spectrograph and InfraRed Imaging System (OSIRIS). In order to correct their mismatch in local time and the diurnal variation of stratospheric NO2, OSIRIS profiles, which were measured just after sunrise, were mapped to the local time of OMI observations using a photochemical boxmodel. Following the profile time adjustment, OSIRIS NO2 stratospheric vertical column densities (VCDs) were calculated. For profiles that did not reach down to the tropopause, VCDs were adjusted using the photochemical model. Using air mass factors from the OMI Standard Product (SP), a new tropospheric NO2 VCD product - referred to as OMI-minus-OSIRIS (OmO) - was generated through limb-nadir matching. To accomplish this, the OMI total SCDs were scaled using correction factors derived from the next-generation SCDs that improve upon the spectral fitting used for the current operational products. One year, 2008, of OmO was generated for 60 deg S to 60 deg N and a cursory evaluation was performed. The OmO product was found to capture the main features of tropospheric NO2, including a background value of about 0.3 x 10(exp 15) molecules per sq cm over the tropical Pacific and values comparable to the OMI operational products over anthropogenic source areas. While additional study is required, these results suggest that a limb-nadir matching approach is feasible for the removal of stratospheric NO2 measured by a polar orbiter from a nadir-viewing instrument in a geostationary orbit such as Tropospheric Emissions: Monitoring of Pollution (TEMPO) or Sentinel-4.

  20. Small Column Ion Exchange

    International Nuclear Information System (INIS)

    Huff, Thomas

    2010-01-01

    Small Column Ion Exchange (SCIX) leverages a suite of technologies developed by DOE across the complex to achieve lifecycle savings. Technologies are applicable to multiple sites. Early testing supported multiple sites. Balance of SRS SCIX testing supports SRS deployment. A forma Systems Engineering Evaluation (SEE) was performed and selected Small Column Ion Exchange columns containing Crystalline Silicotitanate (CST) in a 2-column lead/lag configuration. SEE considered use of Spherical Resorcinol-Formaldehyde (sRF). Advantages of approach at SRS include: (1) no new buildings, (2) low volume of Cs waste in solid form compared to aqueous strip effluent; and availability of downstream processing facilities for immediate processing of spent resin.

  1. Implementation of multidimensional databases in column-oriented NoSQL systems

    OpenAIRE

    Chevalier, Max; El Malki, Mohammed; Kopliku, Arlind; Teste, Olivier; Tournier, Ronan

    2015-01-01

    International audience; NoSQL (Not Only SQL) systems are becoming popular due to known advantages such as horizontal scalability and elasticity. In this paper, we study the implementation of multidimensional data warehouses with columnoriented NoSQL systems. We define mapping rules that transform the conceptual multidimensional data model to logical column-oriented models. We consider three different logical models and we use them to instantiate data warehouses. We focus on data loading, mode...

  2. A new software suite for NO2 vertical profile retrieval from ground-based zenith-sky spectrometers

    International Nuclear Information System (INIS)

    Denis, L.; Roscoe, H.K.; Chipperfield, M.P.; Roozendael, M. van; Goutail, F.

    2005-01-01

    Here we present an operational method to improve accuracy and information content of ground-based measurements of stratospheric NO 2 . The motive is to improve the investigation of trends in NO 2 , and is important because the current trend in NO 2 appears to contradict the trend in its source, suggesting that the stratospheric circulation has changed. To do so, a new software package for retrieving NO 2 vertical profiles from slant columns measured by zenith-sky spectrometers has been created. It uses a Rodgers optimal linear inverse method coupled with a radiative transfer model for calculations of transfer functions between profiles and columns, and a chemical box model for taking into account the NO 2 variations during twilight and during the day. Each model has parameters that vary according to season and location. Forerunners of each model have been previously validated. The scheme maps random errors in the measurements and systematic errors in the models and their parameters on to the retrieved profiles. Initialisation for models is derived from well-established climatologies. The software has been tested by comparing retrieved profiles to simultaneous balloon-borne profiles at mid-latitudes in spring

  3. Recovery of deuterium from H-D gas mixture by thermal diffusion in a multi-concentric-tube column device of fixed total sum of column heights with transverse sampling streams

    International Nuclear Information System (INIS)

    Yeh, H.-M.

    2010-01-01

    The effect of the increment in the number of concentric-tube thermal diffusion columns on the recovery of deuterium from H 2 -HD-D 2 system with fixed total sum of column heights, has been investigated. The equations for predicting the degrees of separation in single-column, double-column and triple-column devices have been derived. Considerable improvement in recovery can be achieved if a multi-column device with larger number of column is employed, instead of a single-column device with column height equal to the same total sum of column heights, especially for the case of higher flow-rate operation and larger total sum of column heights.

  4. A new software suite for NO{sub 2} vertical profile retrieval from ground-based zenith-sky spectrometers

    Energy Technology Data Exchange (ETDEWEB)

    Denis, L. [British Antarctic Survey/NERC, Madingley Road, Cambridge CB3 0ET (United Kingdom); Roscoe, H.K. [British Antarctic Survey/NERC, Madingley Road, Cambridge CB3 0ET (United Kingdom)]. E-mail: h.roscoe@bas.ac.uk; Chipperfield, M.P. [Environment Centre, University of Leeds, Leeds LS2 9JT (United Kingdom); Roozendael, M. van [Belgian Institute for Space Aeronomy (BIRA/IASB), 1180 Brussels (Belgium); Goutail, F. [Service d' Aeronomie du CNRS, BP3, 91271 Verrieres le Buisson (France)

    2005-05-15

    Here we present an operational method to improve accuracy and information content of ground-based measurements of stratospheric NO{sub 2}. The motive is to improve the investigation of trends in NO{sub 2}, and is important because the current trend in NO{sub 2} appears to contradict the trend in its source, suggesting that the stratospheric circulation has changed. To do so, a new software package for retrieving NO{sub 2} vertical profiles from slant columns measured by zenith-sky spectrometers has been created. It uses a Rodgers optimal linear inverse method coupled with a radiative transfer model for calculations of transfer functions between profiles and columns, and a chemical box model for taking into account the NO{sub 2} variations during twilight and during the day. Each model has parameters that vary according to season and location. Forerunners of each model have been previously validated. The scheme maps random errors in the measurements and systematic errors in the models and their parameters on to the retrieved profiles. Initialisation for models is derived from well-established climatologies. The software has been tested by comparing retrieved profiles to simultaneous balloon-borne profiles at mid-latitudes in spring.

  5. Observations of the loss of stratospheric NO2 following volcanic eruptions

    Science.gov (United States)

    Coffey, M. T.; Mankin, William G.

    1993-01-01

    Observations of stratospheric column amounts of nitrogen dioxide (NO2), nitric oxide (NO) and nitric acid (HNO3) have been made following major eruptions of the El Chichon and Mt. Pintatubo volcanoes. Midlatitude abundances of NO2 and NO were reduced by as much as 70% in the months following the appearance of the volcanic aerosols as compared to volcanically quite periods. There are heterogeneous reactions which could occur on the volcanic aerosols to convert NO2 into HNO3 but no commensurate increase in HNO3 column amounts was observed at the times of NO2 decrease.

  6. On the use of harmonized HCHO and NO2 MAXDOAS measurements for the validation of GOME-2 and OMI satellite sensors

    Science.gov (United States)

    Pinardi, Gaia; Hendrick, François; Gielen, Clio; Van Roozendael, Michel; De Smedt, Isabelle; Lambert, Jean-Christopher; Granville, José; Compernolle, Steven; Richter, Andreas; Peters, Enno; Piters, Ankie; Wagner, Thomas; Wang, Yang; Drosoglou, Theano; Bais, Alkis; Wang, Shanshan; Saiz-Lopez, Alfonso

    2017-04-01

    During the last decade, the MAXDOAS technique has been increasingly recognized as a source of Fiducial Reference Measurements (FRM) suitable for the validation of satellite nadir observations of species relevant for climate and air quality like NO2 and HCHO. As part of the EU FP7 QA4ECV (Quality Assurance for Essential Climate Variables; see http://www.qa4ecv.eu/) project, efforts have been recently made to harmonize a network of a dozen of MAXDOAS spectrometers in view of their use to assess the quality of satellite climate data records generated within the same project. Harmonization tasks have addressed both retrieval steps involved in MAXDOAS retrievals, i.e. the DOAS spectral fit providing the differential slant column densities (DSCDs) and the conversion of the retrieved DSCDs into vertical profiles and/or vertical column densities (VCDs). In this work, we illustrate the successive harmonization steps and present the resulting QA4ECV MAXDOAS database v2. The approach adopted for the conversion of slant to vertical columns is based on a simplified look-up-table approach. The strength and limitation of this approach are discussed using reference data retrieved using an optimal estimation scheme. The QA4ECV MAXDOAS database is then used to validate satellite data sets of NO2 and HCHO columns derived from the Aura/OMI and MetOp/GOME-2 sensors. The methodology of comparison, which is also a subject of the QA4ECV project, is reviewed with respect to co-location criteria, impact of vertical and horizontal smoothing and representativeness of validation sites. We conclude by assessing the current strengths and limitations of the existing MAXDOAS datasets for NO2 and HCHO satellite validation.

  7. SO2 columns over China: Temporal and spatial variations using OMI and GOME-2 observations

    International Nuclear Information System (INIS)

    Huanhuan, Yan; Liangfu, Chen; Lin, Su; Jinhua, Tao; Chao, Yu

    2014-01-01

    Enhancements of SO 2 column amounts due to anthropogenic emission sources over China were shown in this paper by using OMI and GOME-2 observations. The temporal and spatial variations of SO 2 columns over China were analyzed for the time period 2005–2010. Beijing and Chongqing showed a high concentration in the SO 2 columns, attributable to the use of coal for power generation in China and the characteristic of terrain and meteorology. The reduction of SO 2 columns over Beijing and surrounding provinces in 2008 was observed by OMI, which confirms the effectiveness of strict controls on pollutant emissions and motor vehicle traffic before and during 2008 Olympic and Paralympic Games. The SO 2 columns over China from GOME-2 (0.2–0.5 DU) were lower than those from OMI (0.6–1 DU), but both showed a decrease in SO 2 columns over northern China since 2008 (except an increase in OMI SO 2 in 2010)

  8. SO2 columns over China: Temporal and spatial variations using OMI and GOME-2 observations

    Science.gov (United States)

    Huanhuan, Yan; Liangfu, Chen; Lin, Su; Jinhua, Tao; Chao, Yu

    2014-03-01

    Enhancements of SO2 column amounts due to anthropogenic emission sources over China were shown in this paper by using OMI and GOME-2 observations. The temporal and spatial variations of SO2 columns over China were analyzed for the time period 2005-2010. Beijing and Chongqing showed a high concentration in the SO2 columns, attributable to the use of coal for power generation in China and the characteristic of terrain and meteorology. The reduction of SO2 columns over Beijing and surrounding provinces in 2008 was observed by OMI, which confirms the effectiveness of strict controls on pollutant emissions and motor vehicle traffic before and during 2008 Olympic and Paralympic Games. The SO2 columns over China from GOME-2 (0.2-0.5 DU) were lower than those from OMI (0.6-1 DU), but both showed a decrease in SO2 columns over northern China since 2008 (except an increase in OMI SO2 in 2010).

  9. Synthesis of novel (-)-epicatechin derivatives as potential endothelial GPER agonists: Evaluation of biological effects.

    Science.gov (United States)

    Sarmiento, Viviana; Ramirez-Sanchez, Israel; Moreno-Ulloa, Aldo; Romero-Perez, Diego; Chávez, Daniel; Ortiz, Miguel; Najera, Nayelli; Correa-Basurto, Jose; Villarreal, Francisco; Ceballos, Guillermo

    2018-02-15

    To potentially identify proteins that interact (i.e. bind) and may contribute to mediate (-)-epicatechin (Epi) responses in endothelial cells we implemented the following strategy: 1) synthesis of novel Epi derivatives amenable to affinity column use, 2) in silico molecular docking studies of the novel derivatives on G protein-coupled estrogen receptor (GPER), 3) biological assessment of the derivatives on NO production, 4) implementation of an immobilized Epi derivative affinity column and, 5) affinity column based isolation of Epi interacting proteins from endothelial cell protein extracts. For these purposes, the Epi phenol and C3 hydroxyl groups were chemically modified with propargyl or mesyl groups. Docking studies of the novel Epi derivatives on GPER conformers at 14 ns and 70 ns demostrated favorable thermodynamic interactions reaching the binding site. Cultures of bovine coronary artery endothelial cells (BCAEC) treated with Epi derivatives stimulated NO production via Ser1179 phosphorylation of eNOS, effects that were attenuated by the use of the GPER blocker, G15. Epi derivative affinity columns yielded multiple proteins from BCAEC. Proteins were electrophoretically separated and inmmunoblotting analysis revealed GPER as an Epi derivative binding protein. Altogether, these results validate the proposed strategy to potentially isolate and identify novel Epi receptors that may account for its biological activity. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. DOAS measurements of NO2 from an ultralight aircraft during the Earth Challenge expedition

    Directory of Open Access Journals (Sweden)

    O. Ronveaux

    2012-08-01

    Full Text Available We report on airborne Differential Optical Absorption Spectroscopy (DOAS measurements of NO2 tropospheric columns above South Asia, the Arabic peninsula, North Africa, and Italy in November and December 2009. The DOAS instrument was installed on an ultralight aircraft involved in the Earth Challenge project, an expedition of seven pilots flying on four ultralight aircraft between Australia and Belgium. The instrument recorded spectra in limb geometry with a large field of view, a set-up which provides a high sensitivity to the boundary layer NO2 while minimizing the uncertainties related to the attitude variations. We compare our measurements with OMI (Ozone Monitoring Instrument and GOME-2 (Global Ozone Monitoring Experiment 2 tropospheric NO2 products when the latter are available. Above Rajasthan and the Po Valley, two areas where the NO2 field is homogeneous, data sets agree very well. Our measurements in these areas are 0.1 ± 0.1 to 3 ± 1 × 1015 molec cm−2 and 2.6 ± 0.8 × 1016 molec cm−2, respectively. Flying downwind of Riyadh, our NO2 measurements show the structure of the megacity's exhaust plume with a higher spatial resolution than OMI. Moreover, our measurements are larger (up to 40% than those seen by satellites. We also derived tropospheric columns when no satellite data were available if it was possible to get information on the visibility from satellite measurements of aerosol optical thickness. This experiment also provides a confirmation for the recent finding of a soil signature above desert.

  11. Expanded Large-Scale Forcing Properties Derived from the Multiscale Data Assimilation System and Its Application to Single-Column Models

    Science.gov (United States)

    Feng, S.; Li, Z.; Liu, Y.; Lin, W.; Toto, T.; Vogelmann, A. M.; Fridlind, A. M.

    2013-12-01

    We present an approach to derive large-scale forcing that is used to drive single-column models (SCMs) and cloud resolving models (CRMs)/large eddy simulation (LES) for evaluating fast physics parameterizations in climate models. The forcing fields are derived by use of a newly developed multi-scale data assimilation (MS-DA) system. This DA system is developed on top of the NCEP Gridpoint Statistical Interpolation (GSI) System and is implemented in the Weather Research and Forecasting (WRF) model at a cloud resolving resolution of 2 km. This approach has been applied to the generation of large scale forcing for a set of Intensive Operation Periods (IOPs) over the Atmospheric Radiation Measurement (ARM) Climate Research Facility's Southern Great Plains (SGP) site. The dense ARM in-situ observations and high-resolution satellite data effectively constrain the WRF model. The evaluation shows that the derived forcing displays accuracies comparable to the existing continuous forcing product and, overall, a better dynamic consistency with observed cloud and precipitation. One important application of this approach is to derive large-scale hydrometeor forcing and multiscale forcing, which is not provided in the existing continuous forcing product. It is shown that the hydrometeor forcing poses an appreciable impact on cloud and precipitation fields in the single-column model simulations. The large-scale forcing exhibits a significant dependency on domain-size that represents SCM grid-sizes. Subgrid processes often contribute a significant component to the large-scale forcing, and this contribution is sensitive to the grid-size and cloud-regime.

  12. Methods for eluting radiocesium from zeolite ion exchange material in a column in the TMI-2 reactor containment building

    International Nuclear Information System (INIS)

    Knauer, J.B.; Campbell, D.O.; Collins, E.D.; King, L.J.

    1982-07-01

    Two alternative procedures were evaluated at Oak Ridge National Laboratory for potential use in eluting the radiocesium from Linde Ionsiv IE-95 zeolite in the pushcart ion exchange column in the TMI-2 containment building. The elution mechanism was iosotopic exchange of the radiocesium with stable cesium. Small zeolite ion exchange columns that had been loaded during ORNL tests of the Submerged Demineralizer System (SDS) flowsheet were eluted during these tests. One column was eluted using 0.25 M CsNO 3 , and a second column was eluted using 0.25 M CsH 2 BO 3 . Both eluent solutions were effective for removing the cesium. The 0.25 CsNO 3 eluent removed approx. 91% of the 137 Cs in 20 bed volumes and approx. 92% in 37.5 bed volumes. The 0.25 M CsH 2 BO 3 eluent removed approx. 82% of the 137 Cs in 20 bed volumes and approx. 85% in 40 bed volumes. In both cases, the radiation levels on the columns were reduced by a factor of approx. 30

  13. Single column and two-column H-D-T distillation experiments at TSTA

    International Nuclear Information System (INIS)

    Yamanishi, T.; Yoshida, H.; Hirata, S.; Naito, T.; Naruse, Y.; Sherman, R.H.; Bartlit, J.R.; Anderson, J.L.

    1988-01-01

    Cryogenic distillation experiments were peformed at TSTA with H-D-T system by using a single column and a two-column cascade. In the single column experiment, fundamental engineering data such as the liquid holdup and the HETP were measured under a variety of operational condtions. The liquid holdup in the packed section was about 10 /approximately/ 15% of its superficial volume. The HETP values were from 4 to 6 cm, and increased slightly with the vapor velocity. The reflux ratio had no effect on the HETP. For the wo-colunn experiemnt, dynamic behavior of the cascade was observed. 8 refs., 7 figs., 2 tabs

  14. Liquid chromatographic determination of aniline and derivatives in environmental waters at nanogram per litre levels using fluorescamine pre-column derivatization

    Energy Technology Data Exchange (ETDEWEB)

    Djozan, D. [Univ. of Tabriz (Iran, Islamic Republic of). Dept. of Analytical Chemistry; Faraj-Zadeh, M.A. [Univ. of Tabriz (Iran, Islamic Republic of). Dept. of Analytical Chemistry

    1995-11-01

    Fluorescamine (fluram) has been used as a fluorogenic compound for pre-column derivatization of aniline and some derivatives. Anilines were derivatized with fluram in citrate buffer media (pH 5.5) to form pyrrolinones. The highly fluorescence pyrrolinones were isolated and pre-concentrated by solid phase extraction. A reversed phase, Spherisorb RP-8 column and tetrahydrofuran: Water:formic acid (42:56:2) mobile phase was used for separation. Detection method was by a sensitive fluorimetric method and quantitation was at 395 and 495 nm. The various parameters such as reaction conditions between anilines and fluram, solid phase extraction and chromatographic separation were optimized. Calibrations were linear over the range considered with excellent correlation coefficients (r>0.999). Relative standard deviations are less than 2.5% and detection limits for aniline, p-toluidine, 4-chloroaniline and 4-bromoaniline were 6, 30, 6 and 8 ng L{sup -1}, respectively. This method has been used successfully for the determination of anilines in environmental waters. (orig.)

  15. Report on a study of the feasibility of use of the COLUMN2 computer program in a probabilistic risk assessment code

    International Nuclear Information System (INIS)

    Hall, R.C.; Liew, S.K.

    1986-10-01

    This report contains the results of a feasibility study carried out on the COLUMN2 computer program to assess its potential for use in time-dependent probabilistic risk assessment code for radiological assessment purposes. COLUMN2 is a program which provides predictions of nuclide transport in a one-dimensional geosphere configuration using a simple Ksub(d) approach for sorption. A moving grid numerical solver is used and the program is therefore potentially capable of handling time-dependent parameters. The reported work covers aspects of code acquisition, loading, theory and structure, necessary code modifications and testing, the last aspect including two documented test cases from the COLUMN2 manual and verification tests derived from international comparison exercises. Recommendations are made as to the required code development of COLUMN2 in order that the code is capable of fulfilling its prime role as defined by the System Design Working Group in a pra code. (author)

  16. Aspartic acid incorporated monolithic columns for affinity glycoprotein purification.

    Science.gov (United States)

    Armutcu, Canan; Bereli, Nilay; Bayram, Engin; Uzun, Lokman; Say, Rıdvan; Denizli, Adil

    2014-02-01

    Novel aspartic acid incorporated monolithic columns were prepared to efficiently affinity purify immunoglobulin G (IgG) from human plasma. The monolithic columns were synthesised in a stainless steel HPLC column (20 cm × 5 mm id) by in situ bulk polymerisation of N-methacryloyl-L-aspartic acid (MAAsp), a polymerisable derivative of L-aspartic acid, and 2-hydroxyethyl methacrylate (HEMA). Monolithic columns [poly(2-hydroxyethyl methacrylate-N-methacryloyl-L-aspartic acid) (PHEMAsp)] were characterised by swelling studies, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The monolithic columns were used for IgG adsorption/desorption from aqueous solutions and human plasma. The IgG adsorption depended on the buffer type, and the maximum IgG adsorption from aqueous solution in phosphate buffer was 0.085 mg/g at pH 6.0. The monolithic columns allowed for one-step IgG purification with a negligible capacity decrease after ten adsorption-desorption cycles. Copyright © 2013 Elsevier B.V. All rights reserved.

  17. Observations of NO2 and O3 during thunderstorm activity using visible spectroscopy

    Science.gov (United States)

    Jadhav, D. B.; Londhe, A. L.; Bose, S.

    1996-08-01

    Simultaneous observations for the total column densities of NO2 , O3 and H2O were carried on using the portable Spectrometer (438-450 nm and 400-450 nm) and the visible Spectrometer (544.4-628 nm) during premonsoon thunderstorms and embedded hail storm activity at Pune (18°32’N & 73°51’E), India. These observations confirm the fact that there is an increase in O3 and NO2 column densities during thunderstorms. The increase in O3 was observed following onset of thunderstorm, while the increase in NO2 was observed only after the thunder flashes occur. This implies that the production mechanisms for O3 and NO2 in thunderstorm are different. The observed column density of NO2 value (1 to 3 × 1017molecules · cm-2) during thunderstorm activity is 10 to 30 times higher than the value (1 × 1016molecules · cm-2) of a normal day total column density. The spectrometric observations and observations of thunder flashes by electric field meter showed that 6.4 × 1025molecules / flash of NO2 are produced. The increased total column density of ozone during thunderstorm period is 1.2 times higher than normal (clear) day ozone concentration. The multiple scattering in the clouds is estimated from H2O and O2 absorption bands in the visible spectral region. Considering this effect the calculated amount of ozone added in the global atmosphere due to thunderstorm activity is 0.26 to 0.52 DU, and the annual production of ozone due to thunderstorm activity is of the order of 4.02 × 1037 molecules / year. The annual NO2 production may be of the order of 2.02 × 1035molecules / year.

  18. Ultra high pressure liquid chromatography. Column permeability and changes of the eluent properties.

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2008-04-11

    The behavior of four similar liquid chromatography columns (2.1mm i.d. x 30, 50, 100, and 150 mm, all packed with fine particles, average d(p) approximately 1.7 microm, of bridged ethylsiloxane/silica hybrid-C(18), named BEH-C(18)) was studied in wide ranges of temperature and pressure. The pressure and the temperature dependencies of the viscosity and the density of the eluent (pure acetonitrile) along the columns were also derived, using the column permeabilities and applying the Kozeny-Carman and the heat balance equations. The heat lost through the external surface area of the chromatographic column was directly derived from the wall temperature of the stainless steel tube measured with a precision of +/-0.2 degrees C in still air and +/-0.1 degrees C in the oven compartment. The variations of the density and viscosity of pure acetonitrile as a function of the temperature and pressure was derived from empirical correlations based on precise experimental data acquired between 298 and 373 K and at pressures up to 1.5 kbar. The measurements were made with the Acquity UPLC chromatograph that can deliver a maximum flow rate of 2 mL/min and apply a maximum column inlet pressure of 1038 bar. The average Kozeny-Carman permeability constant of the columns was 144+/-3.5%. The temperature hence the viscosity and the density profiles of the eluent along the column deviate significantly from linear behavior under high-pressure gradients. For a 1000 bar pressure drop, we measured DeltaT=25-30 K, (Deltaeta/eta) approximately 100%, and (Deltarho/rho) approximately 10%. These results show that the radial temperature profiles are never fully developed within 1% for any of the columns, even under still-air conditions. This represents a practical advantage regarding the apparent column efficiency at high flow rates, since the impact of the differential analyte velocity between the column center and the column wall is not maximum. The interpretation of the peak profiles recorded in

  19. Crystal and molecular structure of the coordination compounds of Er3+ with 1-(methoxydiphenylphosphoryl)-2-diphenylphosphorylbenzene [ErL21(NO3)2]2[Er(NO3)2(H2O)5]0.333(NO3)2.333 · 2.833H2O and its ethyl substituted derivative [ErL22(NO3)2][Er(NO3)5]0.5 · 0.5H2O

    International Nuclear Information System (INIS)

    Polyakova, I. N.; Baulin, V. E.; Ivanova, I. S.; Pyatova, E. N.; Sergienko, V. S.; Tsivadze, A. Yu.

    2015-01-01

    The coordination compounds of Er 3+ with 1-(methoxydiphenylphosphoryl)-2-diphenylphosphorylbenzene [ErL 2 1 (NO 3 ) 2 ] 2 [Er(NO 3 ) 2 (H 2 O) 5 ] 0.333 (NO 3 ) 2.333 · 2.833H 2 O (I) and its ethyl substituted derivative [ErL 2 2 (NO 3 ) 2 ][Er(NO 3 ) 5 ] 0.5 · 0.5H 2 O (II) are synthesized and their crystal structures are studied. I and II contain [ErL 2 (NO 3 ) 2 ] + complex cations of identical composition and close structure. The eight-vertex polyhedron of the Er atom in the shape of a distorted octahedron with two split trans vertices is formed by the O atoms of the phosphoryl groups of L ligands and nitrate anions. L ligands close nine-membered metallocycles. The structures contain spacious channels which are populated differently, namely, by disordered [Er(NO 3 ) 2 (H 2 O) 5 ] + complex cations, NO 3 − anions, and crystallization water molecules in I and disordered [Er(NO 3 ) 5 ] 2− complex anions and crystallization water molecules in II. The IR spectra of I and II are studied

  20. Enrichment of 15N and 18O by chemical exchange reactions between nitrogen oxides (NO, NO2) and aqueous nitric acid

    International Nuclear Information System (INIS)

    Abrudean, M.; Axente, D.; Baldea, A.

    1981-01-01

    The enrichment of 15 N and 18 O by chemical exchange in the NO, NO 2 -H 2 O, HNO 3 system is described. A laboratory experimental plant and a cascade for producing the two isotopes has been used. The production plant consists of two exchange columns for 15 N separation and two 18 O separation columns feeded with nitrogen oxides, depleted of 15 N, from the top of the first 15 N separation column. The by-products nitric acid and sulphuric acid, both depleted of 15 N and 18 O, are of commercial interest. (author)

  1. MINIMUM BRACING STIFFNESS FOR MULTI-COLUMN SYSTEMS: THEORY

    OpenAIRE

    ARISTIZÁBAL-OCHOA, J. DARÍO

    2011-01-01

    A method that determines the minimum bracing stiffness required by a multi-column elastic system to achieve non-sway buckling conditions is proposed. Equations that evaluate the required minimum stiffness of the lateral and torsional bracings and the corresponding “braced" critical buckling load for each column of the story level are derived using the modified stability functions. The following effects are included: 1) the types of end connections (rigid, semirigid, and simple); 2) the bluepr...

  2. Affinity column for purification of the human platelet thromboxane A2/prostaglandin H2 (TXA2/PGH2) receptor

    International Nuclear Information System (INIS)

    Venton, D.L.; Arora, S.K.; Kim, S.O.; Lim, C.T.; Le Breton, G.C.

    1987-01-01

    The TXA 2 /PGH 2 receptor antagonist, 13-azaprostanoic acid (13-APA), was synthesized and used as the immobilized ligand in the affinity column purification of the 13-APA/U46619 binding component in human platelets. Diazo coupling of the ligand to the phenol of this tyr-gly-gly-NH-(CO)-O-Sepharose gave the affinity column material. Isolated platelet membranes were solubilized with detergent, applied directly to the affinity column and the eluate collected as 6 x 70 ml fractions. For each fraction, protein concentration and specific 3 H-13-APA/numberH-U46619 binding were determined. The majority of the applied protein (>98%) eluted in fraction number1. However, the specific 13-APA/U46619 binding per mg of protein was localized in fractions number4 and number5, representing approximately a 500-fold purification of this binding component. These results suggest that the platelet TXA 2 /PGH 2 receptor protein is retarded by this column, and that starting from crude, solubilized platelet membranes, a single pass through the column provides a 500-fold purification of the receptor

  3. Comments on Simplified Calculation Method for Fire Exposed Concrete Columns

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl

    1998-01-01

    The author has developed new simplified calculation methods for fire exposed columns. Methods, which are found In ENV 1992-1-2 chapter 4.3 and in proposal for Danish code of Practise DS411 chapter 9. In the present supporting document the methods are derived and 50 eccentrically loaded fire expos...... columns are calculated and compared to results of full-scale tests. Furthermore 500 columns are calculated in order to present each test result related to a variation of the calculation in time of fire resistance....

  4. Development of West-European PM2.5 and NO2 land use regression models incorporating satellite-derived and chemical transport modelling data

    NARCIS (Netherlands)

    de Hoogh, Kees; Gulliver, John; Donkelaar, Aaron van; Martin, Randall V; Marshall, Julian D; Bechle, Matthew J; Cesaroni, Giulia; Pradas, Marta Cirach; Dedele, Audrius; Eeftens, Marloes|info:eu-repo/dai/nl/315028300; Forsberg, Bertil; Galassi, Claudia; Heinrich, Joachim; Hoffmann, Barbara; Jacquemin, Bénédicte; Katsouyanni, Klea; Korek, Michal; Künzli, Nino; Lindley, Sarah J; Lepeule, Johanna; Meleux, Frederik; de Nazelle, Audrey; Nieuwenhuijsen, Mark; Nystad, Wenche; Raaschou-Nielsen, Ole; Peters, Annette; Peuch, Vincent-Henri; Rouil, Laurence; Udvardy, Orsolya; Slama, Rémy; Stempfelet, Morgane; Stephanou, Euripides G; Tsai, Ming Y; Yli-Tuomi, Tarja; Weinmayr, Gudrun; Brunekreef, Bert|info:eu-repo/dai/nl/067548180; Vienneau, Danielle; Hoek, Gerard|info:eu-repo/dai/nl/069553475

    2016-01-01

    Satellite-derived (SAT) and chemical transport model (CTM) estimates of PM2.5 and NO2 are increasingly used in combination with Land Use Regression (LUR) models. We aimed to compare the contribution of SAT and CTM data to the performance of LUR PM2.5 and NO2 models for Europe. Four sets of models,

  5. Numerical and experimental analysis of time-dependent load transfer in reinforced concrete columns

    Directory of Open Access Journals (Sweden)

    L. T. Kataoka

    Full Text Available A study was conducted to assess the influence of the steel reinforcement ratio in concrete columns on their properties of creep and shrinkage. Experimental tests and three-dimensional finite element-based simulations of the experimental curves from plain concrete cylinders and plain concrete columns derived by curve fitting were performed using the ACI 209 model available in DIANA 9.3. Columns with longitudinal reinforcement ratios of 0%, 1.4% and 2.8%, loaded to 30% and 40% of their 7-day compressive strength, were investigated. The results indicated that numerical simulation does not predict experimental data for a long period. However, simulations fitted with experimental curves derived from plain concrete columns presented values close to those of experimental data for 91 days.

  6. Diurnal, seasonal and long-term variations of global formaldehyde columns inferred from combined OMI and GOME-2 observations

    Science.gov (United States)

    De Smedt, I.; Stavrakou, T.; Hendrick, F.; Danckaert, T.; Vlemmix, T.; Pinardi, G.; Theys, N.; Lerot, C.; Gielen, C.; Vigouroux, C.; Hermans, C.; Fayt, C.; Veefkind, P.; Müller, J.-F.; Van Roozendael, M.

    2015-11-01

    We present the new version (v14) of the BIRA-IASB algorithm for the retrieval of formaldehyde (H2CO) columns from spaceborne UV-visible sensors. Applied to OMI measurements from Aura and to GOME-2 measurements from MetOp-A and MetOp-B, this algorithm is used to produce global distributions of H2CO representative of mid-morning and early afternoon conditions. Its main features include (1) a new iterative DOAS scheme involving three fitting intervals to better account for the O2-O2 absorption, (2) the use of earthshine radiances averaged in the equatorial Pacific as reference spectra, and (3) a destriping correction and background normalisation resolved in the across-swath position. For the air mass factor calculation, a priori vertical profiles calculated by the IMAGES chemistry transport model at 09:30 and 13:30 LT are used. Although the resulting GOME-2 and OMI H2CO vertical columns are found to be highly correlated, some systematic differences are observed. Afternoon columns are generally larger than morning ones, especially in mid-latitude regions. In contrast, over tropical rainforests, morning H2CO columns significantly exceed those observed in the afternoon. These differences are discussed in terms of the H2CO column variation between mid-morning and early afternoon, using ground-based MAX-DOAS measurements available from seven stations in Europe, China and Africa. Validation results confirm the capacity of the combined satellite measurements to resolve diurnal variations in H2CO columns. Furthermore, vertical profiles derived from MAX-DOAS measurements in the Beijing area and in Bujumbura are used for a more detailed validation exercise. In both regions, we find an agreement better than 15 % when MAX-DOAS profiles are used as a priori for the satellite retrievals. Finally, regional trends in H2CO columns are estimated for the 2004-2014 period using SCIAMACHY and GOME-2 data for morning conditions, and OMI for early afternoon conditions. Consistent features

  7. Volumetric Synthetic Aperture Imaging with a Piezoelectric 2-D Row-Column Probe

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Engholm, Mathias; Christiansen, Thomas Lehrmann

    2016-01-01

    The synthetic aperture (SA) technique can be used for achieving real-time volumetric ultrasound imaging using 2-D row-column addressed transducers. This paper investigates SA volumetric imaging performance of an in-house prototyped 3 MHz λ/2-pitch 62+62 element piezoelectric 2-D row-column addres......The synthetic aperture (SA) technique can be used for achieving real-time volumetric ultrasound imaging using 2-D row-column addressed transducers. This paper investigates SA volumetric imaging performance of an in-house prototyped 3 MHz λ/2-pitch 62+62 element piezoelectric 2-D row...

  8. Analysis of amino acid composition in proteins of animal tissues and foods as pre-column o-phthaldialdehyde derivatives by HPLC with fluorescence detection.

    Science.gov (United States)

    Dai, Zhaolai; Wu, Zhenlong; Jia, Sichao; Wu, Guoyao

    2014-08-01

    Studies of protein nutrition and biochemistry require reliable methods for analysis of amino acid (AA) composition in polypeptides of animal tissues and foods. Proteins are hydrolyzed by 6M HCl (110°C for 24h), 4.2M NaOH (105°C for 20 h), or proteases. Analytical techniques that require high-performance liquid chromatography (HPLC) include pre-column derivatization with 4-chloro-7-nitrobenzofurazan, 9-fluorenyl methylchloroformate, phenylisothiocyanate, naphthalene-2,3-dicarboxaldehyde, 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate, and o-phthaldialdehyde (OPA). OPA reacts with primary AA (except cysteine or cystine) in the presence of 2-mercaptoethanol or 3-mercaptopropionic acid to form a highly fluorescent adduct. OPA also reacts with 4-amino-1-butanol and 4-aminobutane-1,3-diol produced from oxidation of proline and 4-hydroxyproline, respectively, in the presence of chloramine-T plus sodium borohydride at 60°C, or with S-carboxymethyl-cysteine formed from cysteine and iodoacetic acid at 25°C. Fluorescence of OPA derivatives is monitored at excitation and emission wavelengths of 340 and 455 nm, respectively. Detection limits are 50 fmol for AA. This technique offers the following advantages: simple procedures for preparation of samples, reagents, and mobile-phase solutions; rapid pre-column formation of OPA-AA derivatives and their efficient separation at room temperature (e.g., 20-25°C); high sensitivity of detection; easy automation on the HPLC apparatus; few interfering side reactions; a stable chromatography baseline for accurate integration of peak areas; and rapid regeneration of guard and analytical columns. Thus, the OPA method provides a useful tool to determine AA composition in proteins of animal tissues (e.g., skeletal muscle, liver, intestine, placenta, brain, and body homogenates) and foods (e.g., milk, corn grain, meat, and soybean meal). Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Precision Column CO2 Measurement from Space Using Broad Band LIDAR

    Science.gov (United States)

    Heaps, William S.

    2009-01-01

    In order to better understand the budget of carbon dioxide in the Earth's atmosphere it is necessary to develop a global high precision understanding of the carbon dioxide column. To uncover the missing sink" that is responsible for the large discrepancies in the budget as we presently understand it, calculation has indicated that measurement accuracy of 1 ppm is necessary. Because typical column average CO2 has now reached 380 ppm this represents a precision on the order of 0.25% for these column measurements. No species has ever been measured from space at such a precision. In recognition of the importance of understanding the CO2 budget to evaluate its impact on global warming the National Research Council in its decadal survey report to NASA recommended planning for a laser based total CO2 mapping mission in the near future. The extreme measurement accuracy requirements on this mission places very strong constraints on the laser system used for the measurement. This work presents an overview of the characteristics necessary in a laser system used to make this measurement. Consideration is given to the temperature dependence, pressure broadening, and pressure shift of the CO2 lines themselves and how these impact the laser system characteristics. We are examining the possibility of making precise measurements of atmospheric carbon dioxide using a broad band source of radiation. This means that many of the difficulties in wavelength control can be treated in the detector portion of the system rather than the laser source. It also greatly reduces the number of individual lasers required to make a measurement. Simplifications such as these are extremely desirable for systems designed to operate from space.

  10. Separation of 15N by isotopic exchange in NO, NO2-HNO3 system under pressure

    International Nuclear Information System (INIS)

    Axente, D.; Baldea, A.; Teaca, C.; Horga, R.; Abrudean, M.

    1998-01-01

    One of the most used method for production of 15 N with 99% at. concentration is the isotopic exchange between gaseous nitrogen oxides and HNO 3 solution 10M: ( 15 NO, 15 NO 2 ) g + H 14 NO 3,l = ( 14 NO, 14 NO 2 ) g + H 15 NO 3,l . The isotopic exchange is characterized by an elemental separation factor α=1.055 at 25 deg. C and atmospheric pressure. Recently, kinetics data pointed to the linear dependence of the exchange rate 15 N/ 14 N(R) on the nitrogen oxide pressure with a rate law R = k[HNO 3 ] 2 · [N 2 O 3 ]. In this work, the influence of the nitrogen oxide pressure on the 15 N separation efficiency was determined by the use of a laboratory equipment with a separation column pack of Helipack type, with dimensions 1.8 mm x 1.8 mm x 0.2 mm. The increase of nitrogen oxide pressure led to a better isotopic transfer between the two counter-flow phases in the column pack. The HETP (Height Equivalent to a Theoretical Plate) determined for a 3.14 ml ·cm -2 · min -1 load is equal to that obtained at atmospheric pressure for a two times lower load. The operation of the equipment for isotopic separation of 15 N at 1.8 atm instead of atmospheric pressure allows doubling the HNO 3 10 M load of the column and consequently, doubling the production rate. A better performance of the separation process at higher pressure is essential for the industrial production of 15 N isotope which is used for the production of uranium nitride in FBR type reactors. (authors)

  11. 19 CFR 191.173 - Imported duty-paid derivatives (no manufacture).

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Imported duty-paid derivatives (no manufacture). 191.173 Section 191.173 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND... § 191.173 Imported duty-paid derivatives (no manufacture). When the basis for drawback under 19 U.S.C...

  12. Simultaneous determination of diastereoisomeric and enantiomeric impurities in SSS-octahydroindole-2-carboxylic acid by chiral high-performance liquid chromatography with pre-column derivatization.

    Science.gov (United States)

    Wang, Jin Zhao; Zeng, Su; Hu, Gong Yun; Wang, Dan Hua

    2009-04-10

    SSS-Octahydroindole-2-carboxylic acid (SSS-Oic) is a key intermediate used in the synthesis of some angiotensin-converting enzyme (ACE) inhibitors. The separation of diastereoisomers and enantiomers of Oic was performed using a pre-column derivatization chiral HPLC method. Phenyl isothiocyanate (PITC) was used as the derivatization reagent. Three PITC derivatives of Oic stereoisomers were separated on an Ultron ES-OVM chiral column (150 mm x 4.6 mm, 5 microm). Derivatization conditions such as reaction temperature, reaction time and derivatization reagent concentration were investigated. The chromatographic conditions for separation of the three PITC-Oic derivatives were optimized. The method was successfully applied in the diastereoisomeric and enantiomeric purity test of SSS-Oic.

  13. Retrieval of tropospheric NO2 vertical column densities and aerosol optical properties form MAXDOAS measurements in Yangtze River Delta, China

    Science.gov (United States)

    Hao, Nan; Van. Roozendael, Michel; Ding, Aijun; Zhou, Bin; Hendrick, François; Shen, Yicheng; Wang, Tin; Valks, Pieter

    2014-05-01

    Air pollution is one of the most important environmental problems in developing Asian countries like China. Due to huge consumption of fossil fuels and rapid increase of traffic emissions in the past decades, many regions in China have been experiencing heavy air pollution. The Yangtze River Delta (YRD) region includes the mega-city Shanghai and the well-industrialized and urbanized areas of Zhejiang Province and Jiangsu Province, with over ten large cities, such as Hangzhou, Suzhou and Nanjing. Covering only 2% land area, this region produces over 20% of China's Gross Domestic Product (GDP) which makes it the most densely populated region and one of the most polluted regions in China. For instance, there more than 60% of a year was haze days with poor visibility in Shanghai over the last few years. In the YRD region, knowledge gaps still exist in the understanding of the source and transport of air pollutants because only few measurement studies have been conducted. MAX-DOAS measurements were performed in Shanghai city center and Wujiang (border of Shanghai and Jiangsu Province) from 2010 to 2012 and in Nanjing (capital of Jiangsu Province) from April 2013. A retrieval algorithm, based on an on-line implementation of the radiative transfer code LIDORT and the optimal estimation technique, has been used to provide information on aerosol extinction vertical profiles. The total aerosol optical depths (AODs) calculated from the retrieved profiles were compared to MODIS, AERONET and local PM measurements. The aerosol information was input to LIDORT to calculate NO2 air mass factors. The retrieved tropospheric NO2 vertical column densities (VCDs) were compared to in-situ and satellite NO2 measurements.

  14. New proposal to measure NO2 formation rate from NO emissions in the atmosphere

    International Nuclear Information System (INIS)

    Frins, Erna; Osorio, MatIas; Casaballe, Nicolas; Wagner, Thomas; Platt, Ulrich

    2011-01-01

    As result from combustion processes, SO 2 , NO, NO 2 and other substances are emitted in the atmosphere. We present a new method to measure the formation rate of a trace gas (e.g., NO 2 ), whose precursor (NO) was emitted in the atmosphere by a source like a stack. In the case under study, the presence of ozone determines the formation of NO 2 . We will demonstrate that measuring the slant column densities across the emitted plume and knowing the flux of another trace gas (e.g. SO 2 ), also emitted by the source but that could be considered stable under the conditions of the observation, it is possible to monitor remotely (from an arbitrary location) the formation rate of NO 2 due to conversion of NO to NO 2 .

  15. Mobile mini-DOAS measurement of the outflow of NO2 and HCHO from Mexico City

    Directory of Open Access Journals (Sweden)

    L. Molina

    2009-08-01

    Full Text Available We here present the results from mobile measurements using two ground-based zenith viewing Differential Optical Absorption Spectroscopy (DOAS instruments. The measurement was performed in a cross-section of the plume from the Mexico City Metropolitan Area (MCMA on 10 March 2006 as part of the MILAGRO field campaign. The two instruments operated in the UV and the visible wavelength region respectively and have been used to derive the differential vertical columns of HCHO and NO2 above the measurement route. This is the first time the mobile mini-DOAS instrument has been able to measure HCHO, one of the chemically most important and interesting gases in the polluted urban atmosphere. Using a mass-averaged wind speed and wind direction from the WRF model the instantaneous flux of HCHO and NO2 has been calculated from the measurements and the results are compared to the CAMx chemical model. The calculated flux through the measured cross-section was 1.9 (1.5–2.2 kg/s of HCHO and 4.4 (4.0–5.0 kg/s of NO2 using the UV instrument and 3.66 (3.63–3.73 kg/s of NO2 using the visible light instrument. The modeled values from CAMx for the outflow of both NO2 and HCHO, 1.1 and 3.6 kg/s, respectively, show a reasonable agreement with the measurement derived fluxes.

  16. Family of columns isospectral to gravity-loaded columns with tip force: A discrete approach

    Science.gov (United States)

    Ramachandran, Nirmal; Ganguli, Ranjan

    2018-06-01

    A discrete model is introduced to analyze transverse vibration of straight, clamped-free (CF) columns of variable cross-sectional geometry under the influence of gravity and a constant axial force at the tip. The discrete model is used to determine critical combinations of loading parameters - a gravity parameter and a tip force parameter - that cause onset of dynamic instability in the CF column. A methodology, based on matrix-factorization, is described to transform the discrete model into a family of models corresponding to weightless and unloaded clamped-free (WUCF) columns, each with a transverse vibration spectrum isospectral to the original model. Characteristics of models in this isospectral family are dependent on three transformation parameters. A procedure is discussed to convert the isospectral discrete model description into geometric description of realistic columns i.e. from the discrete model, we construct isospectral WUCF columns with rectangular cross-sections varying in width and depth. As part of numerical studies to demonstrate efficacy of techniques presented, frequency parameters of a uniform column and three types of tapered CF columns under different combinations of loading parameters are obtained from the discrete model. Critical combinations of these parameters for a typical tapered column are derived. These results match with published results. Example CF columns, under arbitrarily-chosen combinations of loading parameters are considered and for each combination, isospectral WUCF columns are constructed. Role of transformation parameters in determining characteristics of isospectral columns is discussed and optimum values are deduced. Natural frequencies of these WUCF columns computed using Finite Element Method (FEM) match well with those of the given gravity-loaded CF column with tip force, hence confirming isospectrality.

  17. Simultaneous removal of SO2 and NOX with ammonia absorbent in a packed column

    International Nuclear Information System (INIS)

    Jia, Yong; Du, Daqian; Zhang, Xinxi; Ding, Xilou; Zhong, Oin

    2013-01-01

    Catalytic oxidation of NO followed by simultaneous removal of SO 2 and NO X with ammonia is a promising method for control of coal-fired flue gas pollutants. We investigated simultaneous absorption of SO 2 and NO X in a packed column with ammonia, and found that SO 2 and NO X could promote absorption with each other in the process of simultaneous removal SO 2 and NO X . The removal efficiency of SO 2 and NO X was, respectively, about 98% and 70.9% at pH 5.5, temperature 323.15 K, SO 2 concentration 1,800x10 −6 , NO X concentration 400x10 −6 and m NO2 /m NO 1 in our experimental system. The experimental results also show that the formation of sulfite oxidized by reacting with dissolved NO 2 and the molar ratio of sulfite to total sulfur is more than 0.8 in the solution. Accordingly, the energy consumption for sulfite oxidation would be greatly reduced in the process of simultaneous desulfurization and denitrification with ammonia

  18. The version 3 OMI NO2 standard product

    Directory of Open Access Journals (Sweden)

    N. A. Krotkov

    2017-09-01

    Full Text Available We describe the new version 3.0 NASA Ozone Monitoring Instrument (OMI standard nitrogen dioxide (NO2 products (SPv3. The products and documentation are publicly available from the NASA Goddard Earth Sciences Data and Information Services Center (https://disc.gsfc.nasa.gov/datasets/OMNO2_V003/summary/. The major improvements include (1 a new spectral fitting algorithm for NO2 slant column density (SCD retrieval and (2 higher-resolution (1° latitude and 1.25° longitude a priori NO2 and temperature profiles from the Global Modeling Initiative (GMI chemistry–transport model with yearly varying emissions to calculate air mass factors (AMFs required to convert SCDs into vertical column densities (VCDs. The new SCDs are systematically lower (by ∼ 10–40 % than previous, version 2, estimates. Most of this reduction in SCDs is propagated into stratospheric VCDs. Tropospheric NO2 VCDs are also reduced over polluted areas, especially over western Europe, the eastern US, and eastern China. Initial evaluation over unpolluted areas shows that the new SPv3 products agree better with independent satellite- and ground-based Fourier transform infrared (FTIR measurements. However, further evaluation of tropospheric VCDs is needed over polluted areas, where the increased spatial resolution and more refined AMF estimates may lead to better characterization of pollution hot spots.

  19. Next-Generation Aura/OMI NO2 and SO2 Products

    Science.gov (United States)

    Krotkov, Nickolay; Yang, Kai; Bucsela, Eric; Lamsal, Lok; Celarier, Edward; Swartz, William; Carn, Simon; Bhartia, Pawan; Gleason, James; Pickering, Ken; hide

    2011-01-01

    The measurement of both SO2 and NO2 gases are recognized as an essential component of atmospheric composition missions. We describe current capabilities and limitations of the operational Aura/OMI NO2 and SO2 data that have been used by a large number of researchers. Analyses of the data and validation studies have brought to light a number of areas in which these products can be expanded and improved. Major improvements for new NASA standard (SP) NO2 product include more accurate tropospheric and stratospheric column amounts, along with much improved error estimates and diagnostics. Our approach uses a monthly NO2 climatology based on the NASA Global Modeling Initiative (GMI) chemistry-transport model and takes advantage of OMI data from cloudy scenes to find clean areas where the contribution from the trap NO2 column is relatively small. We then use a new filtering, interpolation and smoothing techniques for separating the stratospheric and tropospheric components of NO2, minimizing the influence of a priori information. The new algorithm greatly improves the structure of stratospheric features relative to the original SP. For the next-generation OMI SO2 product we plan to implement operationally the offline iterative spectral fitting (ISF) algorithm and re-process the OMI Level-2 SO2 dataset using a priori SO2 and aerosol profiles, clouds, and surface reflectivity appropriate for observation conditions. This will improve the ability to detect and quantify weak tropospheric SO2 loadings. The new algorithm is validated using aircraft in-situ data during field campaigns in China (2005 and 2008) and in Maryland (Frostburg, 2010 and DISCOVER-AQ in July 2011). The height of the SO2 plumes will also be estimated for high SO2 loading cases (e.g., volcanic eruptions). The same SO2 algorithm will be applied to the data from OMPS sensor to be launched on NPP satellite later this year. The next-generation NO2 and SO2 products will provide critical information (e

  20. Comparison of high-latitude line-of-sight ozone column density with derived ozone fields and the effects of horizontal inhomogeneity

    Directory of Open Access Journals (Sweden)

    W. H. Swartz

    2006-01-01

    Full Text Available Extensive ozone measurements were made during the second SAGE III Ozone Loss and Validation Experiment (SOLVE II. We compare high-latitude line-of-sight (LOS slant column ozone measurements from the NASA DC-8 to ozone simulated by forward integration of measurement-derived ozone fields constructed both with and without the assumption of horizontal homogeneity. The average bias and rms error of the simulations assuming homogeneity are relatively small (−6 and 10%, respectively in comparison to the LOS measurements. The comparison improves significantly (−2% bias; 8% rms error using forward integrations of three-dimensional proxy ozone fields reconstructed from potential vorticity-O3 correlations. The comparisons provide additional verification of the proxy fields and quantify the influence of large-scale ozone inhomogeneity. The spatial inhomogeneity of the atmosphere is a source of error in the retrieval of trace gas vertical profiles and column abundance from LOS measurements, as well as a complicating factor in intercomparisons that include LOS measurements at large solar zenith angles.

  1. Anomalous electrical signals associated with microbial activity: Results from Iron and Nitrate-Reducing Columns

    Science.gov (United States)

    Aaron, R. B.; Zheng, Q.; Flynn, P.; Singha, K.; Brantley, S.

    2008-12-01

    Three flow-through columns outfitted with Ag/AgCl electrodes were constructed to test the effects of different microbial processes on the geophysical measurements of self potential (SP), bulk electrical conductivity (σ b), and induced polarization (IP). The columns were filled with sieved, Fe-bearing subsurface sediment from the Delmarva Peninsula near Oyster, VA, inoculated (9:1 ratio) with a freshly-collected, shallow subsurface sediment from a wetland floodplain (Dorn Creek) near Madison, WI. Each of the columns was fed anoxic and sterile PIPES buffered artificial groundwater (PBAGW) containing different concentrations of acetate and nitrate. The medium fed to Column 1 (nitrate-reducing) was amended with 100 μM acetate and 2 mM nitrate. Column 2 (iron-reducing) was run with PBAGW containing 1.0 mM acetate and 0 mM nitrate. Column 3 (alternating redox state) was operated under conditions designed to alternately stimulate nitrate-reducing and iron-reducing populations to provide conditions, i.e., the presence of both nitrate and microbially-produced Fe(II), that would allow growth of nitrate-dependent Fe(II)-oxidizing populations. We operated Column 3 with a cycling strategy of 14-18 days of high C medium (1 mM acetate and 100 μ M nitrate) followed by 14-18 days of low C medium (100 μ M acetate and 2 mM nitrate). Effluent chemistry (NO3-, NO2-, NH4+, acetate, and Fe2+) was sampled daily for four months so as to be concurrent with the electrical measurements. We observed chemical evidence of iron reduction (dissolved [Fe(II)] = 0.2mM) in the effluent from the iron reduction and alternating redox columns. Chemical depletion of NO3- ([NO3-] ranged from 1 to 0.02mM), the production of NO2-, and possible production of NH4+ (0.2 mM) was observed in the nitrate reducing column as well as the alternating redox column. All three columns displayed loss of acetate as microbial activity progressed. σ b remained constant in the alternating redox column (~0.15 S

  2. Purification of antibody against Ara h 2 by a homemade immunoaffinity chromatography column.

    Science.gov (United States)

    Wu, Zhihua; Li, Kun; Zhan, Shaode; Tong, Ping; Li, Xin; Yang, Anshu; Chen, Hongbing

    2017-09-14

    Antibodies are used extensively in numerous applications both in vivo and in vitro. To purify anti-Ara h 2 polyclonal antibody, a homemade immunoaffinity chromatography (IAC) column method was established. The properties of homemade column were compared with those of the mAb affinity protein G (MPG) agarose high flow, a commercially available column successfully used in capturing polyclonal antibodies. During antibody purification from rabbits' antiserum against Ara h 2, the column capacity, recovery, and purification factor were characterized for IAC and MPG. The homemade IAC could separate the corresponding antibody with higher specificity and lower cost but with lower recovery and column capacity than those of MPG. Thus, the homemade IAC is a specific, inexpensive, and suitable method that can be used for various laboratory purifications.

  3. CO2-laser--produced plasma columns in a solenoidal magnetic field

    International Nuclear Information System (INIS)

    Offenberger, A.A.; Cervenan, M.R.; Smy, P.R.

    1976-01-01

    A 1-GW CO 2 laser pulse has been used to produce extended column breakdown of hydrogen at low pressure in a 20-cm-long solenoid. Magnetic fields of up to 110 kG were used to inhibit radial losses of the plasma column. A differential pumping scheme was devised to prevent formation of an opaque absorption wave travelling out of the solenoid back toward the focusing lens. Target burns give direct evidence for trapped laser beam propagation along the plasma column

  4. Ion chromatography for determination of nitrite and nitrate in seawater using monolithic ODS columns.

    Science.gov (United States)

    Ito, Kazuaki; Takayama, Yohichi; Makabe, Nobuyuki; Mitsui, Ryo; Hirokawa, Takeshi

    2005-08-12

    A fast and highly sensitive ion chromatographic method using monolithic ODS columns was developed for the determination of nitrite (NO2-) and nitrate (NO3-) in seawater. Two monolithic ODS columns (50 mm x 4.6 mm i.d. + 100 mm x 4.6 mm i.d.) connected in series were coated and equilibrated with 5 mM cetyltrimethylammonium chloride (CTAC) aqueous solution. The column efficiency with 0.5 M NaCl as the mobile phase did not decrease in spite of the increase in flow rate of the mobile phase. Thus, good chromatograms were obtained within 3 minutes for NO2- and NO3 in artificial seawater without interferences by coexisting ions. The detection limit (S/N = 3) with UV detection at 225 nm was 0.8 and 1.6 microg/L for NO2- and NO3-, respectively. The characteristics of the monolithic CTA(+)-coated ODS columns were discussed. The present method was successfully applied to the fast and sensitive determination of NO2- and NO3- in real seawater samples.

  5. Derivation of Tropospheric Ozone Climatology and Trends from TOMS Data

    Science.gov (United States)

    Newchurch, Michael J.; McPeters, Rich; Logan, Jennifer; Kim, Jae-Hwan

    2002-01-01

    This research addresses the following three objectives: (1) Derive tropospheric ozone columns from the TOMS instruments by computing the difference between total-ozone columns over cloudy areas and over clear areas in the tropics; (2) Compute secular trends in Nimbus-7 derived tropospheric Ozone column amounts and associated potential trends in the decadal-scale tropical cloud climatology; (3) Explain the occurrence of anomalously high ozone retrievals over high ice clouds.

  6. Airborne 2-Micron Double-Pulsed Integrated Path Differential Absorption Lidar for Column CO2 Measurement

    Science.gov (United States)

    Singh, Upendra N.; Yu, Jirong; Petros, Mulugeta; Refaat, Tamer F.; Remus, Ruben G.; Fay, James J.; Reithmaier, Karl

    2014-01-01

    Double-pulse 2-micron lasers have been demonstrated with energy as high as 600 millijouls and up to 10 Hz repetition rate. The two laser pulses are separated by 200 microseconds and can be tuned and locked separately. Applying double-pulse laser in DIAL system enhances the CO2 measurement capability by increasing the overlap of the sampled volume between the on-line and off-line. To avoid detection complicity, integrated path differential absorption (IPDA) lidar provides higher signal-to-noise ratio measurement compared to conventional range-resolved DIAL. Rather than weak atmospheric scattering returns, IPDA rely on the much stronger hard target returns that is best suited for airborne platforms. In addition, the IPDA technique measures the total integrated column content from the instrument to the hard target but with weighting that can be tuned by the transmitter. Therefore, the transmitter could be tuned to weight the column measurement to the surface for optimum CO2 interaction studies or up to the free troposphere for optimum transport studies. Currently, NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micron IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

  7. A green chemoselective one-pot protocol for expeditious synthesis of symmetric pyranodipyrimidine derivatives using ZrOCl2.8H2O

    Directory of Open Access Journals (Sweden)

    Mehdi Rimaz

    2016-09-01

    Full Text Available A convenient, highly efficient and time economic method has been described for the chemo- and regioselective synthesis of 5-aryloyl-1,3,7,9-tetraalkyl-2,8-dithioxo-2,3,8,9-tetrahydro-1H-pyrano[2,3-d:6,5-dˊ]dipyrimidine-4,6(5H,7H-diones derivatives by one-pot two-component reaction of 1,3-diethyl-2-thiobarbituric acid or 1,3-dimethyl-2-thiobarbituric acid with substituted arylglyoxalmonohydrates using commercially available zirconium (IV oxydichloride octahydrate (ZrOCl2.8H2O as green Lewis acid catalyst. This method is associated with some attractive characteristics such as good selectivity, very short reaction time, high yield of products, cleaner reaction profile, no harmful by-product, cheap and environmental benign catalyst, simple experimental and work-up procedure. This procedure does not require solvent separation and purification steps such as column chromatography.

  8. Intercomparison of ground-based ozone and NO2 measurements during the MANTRA 2004 campaign

    Directory of Open Access Journals (Sweden)

    K. Strong

    2007-11-01

    Full Text Available The MANTRA (Middle Atmosphere Nitrogen TRend Assessment 2004 campaign took place in Vanscoy, Saskatchewan, Canada (52° N, 107° W from 3 August to 15 September, 2004. In support of the main balloon launch, a suite of five zenith-sky and direct-Sun-viewing UV-visible ground-based spectrometers was deployed, primarily measuring ozone and NO2 total columns. Three Fourier transform spectrometers (FTSs that were part of the balloon payload also performed ground-based measurements of several species, including ozone. Ground-based measurements of ozone and NO2 differential slant column densities from the zenith-viewing UV-visible instruments are presented herein. They are found to partially agree within NDACC (Network for the Detection of Atmospheric Composition Change standards for instruments certified for process studies and satellite validation. Vertical column densities of ozone from the zenith-sky UV-visible instruments, the FTSs, a Brewer spectrophotometer, and ozonesondes are compared, and found to agree within the combined error estimates of the instruments (15%. NO2 vertical column densities from two of the UV-visible instruments are compared, and are also found to agree within combined error (15%.

  9. A New Retrieval Algorithm for OMI NO2: Tropospheric Results and Comparisons with Measurements and Models

    Science.gov (United States)

    Swartz, W. H.; Bucesla, E. J.; Lamsal, L. N.; Celarier, E. A.; Krotkov, N. A.; Bhartia, P, K,; Strahan, S. E.; Gleason, J. F.; Herman, J.; Pickering, K.

    2012-01-01

    Nitrogen oxides (NOx =NO+NO2) are important atmospheric trace constituents that impact tropospheric air pollution chemistry and air quality. We have developed a new NASA algorithm for the retrieval of stratospheric and tropospheric NO2 vertical column densities using measurements from the nadir-viewing Ozone Monitoring Instrument (OMI) on NASA's Aura satellite. The new products rely on an improved approach to stratospheric NO2 column estimation and stratosphere-troposphere separation and a new monthly NO2 climatology based on the NASA Global Modeling Initiative chemistry-transport model. The retrieval does not rely on daily model profiles, minimizing the influence of a priori information. We evaluate the retrieved tropospheric NO2 columns using surface in situ (e.g., AQS/EPA), ground-based (e.g., DOAS), and airborne measurements (e.g., DISCOVER-AQ). The new, improved OMI tropospheric NO2 product is available at high spatial resolution for the years 200S-present. We believe that this product is valuable for the evaluation of chemistry-transport models, examining the spatial and temporal patterns of NOx emissions, constraining top-down NOx inventories, and for the estimation of NOx lifetimes.

  10. Estimates of Free-tropospheric NO2 Abundance from the Aura Ozone Monitoring Instrument (OMI) Using Cloud Slicing Technique

    Science.gov (United States)

    Choi, S.; Joiner, J.; Krotkov, N. A.; Choi, Y.; Duncan, B. N.; Celarier, E. A.; Bucsela, E. J.; Vasilkov, A. P.; Strahan, S. E.; Veefkind, J. P.; Cohen, R. C.; Weinheimer, A. J.; Pickering, K. E.

    2013-12-01

    Total column measurements of NO2 from space-based sensors are of interest to the atmospheric chemistry and air quality communities; the relatively short lifetime of near-surface NO2 produces satellite-observed hot-spots near pollution sources including power plants and urban areas. However, estimates of NO2 concentrations in the free-troposphere, where lifetimes are longer and the radiative impact through ozone formation is larger, are severely lacking. Such information is critical to evaluate chemistry-climate and air quality models that are used for prediction of the evolution of tropospheric ozone and its impact of climate and air quality. Here, we retrieve free-tropospheric NO2 volume mixing ratio (VMR) using the cloud slicing technique. We use cloud optical centroid pressures (OCPs) as well as collocated above-cloud vertical NO2 columns (defined as the NO2 column from top of the atmosphere to the cloud OCP) from the Ozone Monitoring Instrument (OMI). The above-cloud NO2 vertical columns used in our study are retrieved independent of a priori NO2 profile information. In the cloud-slicing approach, the slope of the above-cloud NO2 column versus the cloud optical centroid pressure is proportional to the NO2 volume mixing ratio (VMR) for a given pressure (altitude) range. We retrieve NO2 volume mixing ratios and compare the obtained NO2 VMRs with in-situ aircraft profiles measured during the NASA Intercontinental Chemical Transport Experiment Phase B (INTEX-B) campaign in 2006. The agreement is good when proper data screening is applied. In addition, the OMI cloud slicing reports a high NO2 VMR where the aircraft reported lightning NOx during the Deep Convection Clouds and Chemistry (DC3) campaign in 2012. We also provide a global seasonal climatology of free-tropospheric NO2 VMR in cloudy conditions. Enhanced NO2 in free troposphere commonly appears near polluted urban locations where NO2 produced in the boundary layer may be transported vertically out of the

  11. Radiotracer Imaging of Sediment Columns

    Science.gov (United States)

    Moses, W. W.; O'Neil, J. P.; Boutchko, R.; Nico, P. S.; Druhan, J. L.; Vandehey, N. T.

    2010-12-01

    Nuclear medical PET and SPECT cameras routinely image radioactivity concentration of gamma ray emitting isotopes (PET - 511 keV; SPECT - 75-300 keV). We have used nuclear medical imaging technology to study contaminant transport in sediment columns. Specifically, we use Tc-99m (T1/2 = 6 h, Eγ = 140 keV) and a SPECT camera to image the bacteria mediated reduction of pertechnetate, [Tc(VII)O4]- + Fe(II) → Tc(IV)O2 + Fe(III). A 45 mL bolus of Tc-99m (32 mCi) labeled sodium pertechnetate was infused into a column (35cm x 10cm Ø) containing uranium-contaminated subsurface sediment from the Rifle, CO site. A flow rate of 1.25 ml/min of artificial groundwater was maintained in the column. Using a GE Millennium VG camera, we imaged the column for 12 hours, acquiring 44 frames. As the microbes in the sediment were inactive, we expected most of the iron to be Fe(III). The images were consistent with this hypothesis, and the Tc-99m pertechnetate acted like a conservative tracer. Virtually no binding of the Tc-99m was observed, and while the bolus of activity propagated fairly uniformly through the column, some inhomogeneity attributed to sediment packing was observed. We expect that after augmentation by acetate, the bacteria will metabolically reduce Fe(III) to Fe(II), leading to significant Tc-99m binding. Imaging sediment columns using nuclear medicine techniques has many attractive features. Trace quantities of the radiolabeled compounds are used (micro- to nano- molar) and the half-lives of many of these tracers are short (Image of Tc-99m distribution in a column containing Rifle sediment at four times.

  12. Enrichment of heavy water in thermal-diffusion columns connected in series

    International Nuclear Information System (INIS)

    Yeh, Ho-Ming; Chen, Liu Yi

    2009-01-01

    The separation equations for enrichment of heavy water from water isotope mixture by thermal diffusion in multiple columns connected in series, have been derived based on one column design developed in previous work. The improvement in separation is achievable by operating in a double-column device, instead of in a single-column device, with the same total column length. It is also found that further improvement in separation is obtainable if a triple-column device is employed, except for operating under small total column length and low flow rate.

  13. Models for wet scrubbing of SO{sub 2} and NO{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Brogren, C

    1997-02-01

    Combustion of fossil fuels is the main source for emissions of sulfur dioxide and nitrogen oxides. Emission regulations and the growing environmental awareness will make great demands upon cost-effective deSO{sub 2} and deNO{sub x} techniques in the future. To be able to optimize existing techniques it is crucial to increase the understanding of the processes taking place within the scrubber, i.e. chemistry, mass transfer and fluid dynamics. Mathematical modeling is an important tool for increasing the understanding. This research work was divided into two different parts: the first part focused on identifying suitable absorbents for wet NO{sub x} removal and the second part focused on deriving a model for absorption of SO{sub 2} into a limestone slurry, wet flue gas desulfurization. The ability to absorb NO{sub x} were tested in a bubbler for the most common oxidizing agents and EDTA. Further experiments were done with the most promising absorbents, NaClO{sub 2} and KMnO{sub 4}, in a packed column where the chemistry was studied in more detail. The absorption process was modeled and rate constants describing the absorption were estimated. A model based on the penetration theory was derived to calculate the absorption of SO{sub 2} into a limestone slurry droplet. The model includes instantaneous acid-base reactions as well as reactions with finite rates, e.g. limestone dissolution, CO{sub 2} hydrolysis, etc. The model was used to quantify the extent of spatial variations in mass transfer within a spray scrubber and the impact of the reactions with finite rate on SO{sub 2} mass transfer. Due to the significance of limestone dissolution a separate model taking into account the impact of the residence time distribution of a continuous system on the particle size distribution was derived. The model was verified by dissolution experiments in a continuous stirred tank reactor. 81 refs, 34 figs, 10 tabs

  14. Water table fluctuations and soil biogeochemistry: An experimental approach using an automated soil column system

    Science.gov (United States)

    Rezanezhad, F.; Couture, R.-M.; Kovac, R.; O'Connell, D.; Van Cappellen, P.

    2014-02-01

    Water table fluctuations significantly affect the biological and geochemical functioning of soils. Here, we introduce an automated soil column system in which the water table regime is imposed using a computer-controlled, multi-channel pump connected to a hydrostatic equilibrium reservoir and a water storage reservoir. The potential of this new system is illustrated by comparing results from two columns filled with 45 cm of the same homogenized riparian soil. In one soil column the water table remained constant at -20 cm below the soil surface, while in the other the water table oscillated between the soil surface and the bottom of the column, at a rate of 4.8 cm d-1. The experiment ran for 75 days at room temperature (25 ± 2 °C). Micro-sensors installed at -10 and -30 cm below the soil surface in the stable water table column recorded constant redox potentials on the order of 600 and -200 mV, respectively. In the fluctuating water table column, redox potentials at the same depths oscillated between oxidizing (∼700 mV) and reducing (∼-100 mV) conditions. Pore waters collected periodically and solid-phase analyses on core material obtained at the end of the experiment highlighted striking geochemical differences between the two columns, especially in the time series and depth distributions of Fe, Mn, K, P and S. Soil CO2 emissions derived from headspace gas analysis exhibited periodic variations in the fluctuating water table column, with peak values during water table drawdown. Transient redox conditions caused by the water table fluctuations enhanced microbial oxidation of soil organic matter, resulting in a pronounced depletion of particulate organic carbon in the midsection of the fluctuating water table column. Denaturing Gradient Gel Electrophoresis (DGGE) revealed the onset of differentiation of the bacterial communities in the upper (oxidizing) and lower (reducing) soil sections, although no systematic differences in microbial community structure

  15. Annular pulse column development studies

    International Nuclear Information System (INIS)

    Benedict, G.E.

    1980-01-01

    The capacity of critically safe cylindrical pulse columns limits the size of nuclear fuel solvent extraction plants because of the limited cross-sectional area of plutonium, U-235, or U-233 processing columns. Thus, there is a need to increase the cross-sectional area of these columns. This can be accomplished through the use of a column having an annular cross section. The preliminary testing of a pilot-plant-scale annular column has been completed and is reported herein. The column is made from 152.4-mm (6-in.) glass pipe sections with an 89-mm (3.5-in.) o.d. internal tube, giving an annular width of 32-mm (1.25-in.). Louver plates are used to swirl the column contents to prevent channeling of the phases. The data from this testing indicate that this approach can successfully provide larger-cross-section critically safe pulse columns. While the capacity is only 70% of that of a cylindrical column of similar cross section, the efficiency is almost identical to that of a cylindrical column. No evidence was seen of any non-uniform pulsing action from one side of the column to the other

  16. [Analysis of hydrogen isotopes by gas chromatography using a MnCl2 coated γ-Al2O3 capillary packed column].

    Science.gov (United States)

    Chen, Ping; Fu, Xiaolong; Hu, Peng; Xiao, Chengjian; Ren, Xingbi; Xia, Xiulong; Wang, Heyi

    2017-07-08

    The conventional packed column gas chromatographic analysis of hydrogen isotopes has low column efficiency, broad peak and long retention time. In this work, a γ -Al 2 O 3 with MnCl 2 coated capillary packed column was tested at cryogenic temperature. The systematic column efficiency analysis and the hydrogen isotopes analytical technique research had been carried out. The results showed that, the γ -Al 2 O 3 with MnCl 2 coating could greatly improve the surface degree of order, pore structure and adsorption properties. Also the o -H 2 peak and p -H 2 peak were eluted in a single area. The γ -Al 2 O 3 with MnCl 2 coating was packed into a 0.53 mm inner diameter and 1.0 m long fused silica capillary column. It had a good linear relationship used this column with thermal conductivity detector (TCD) to detect the volume concentrations of hydrogen isotopes from 1 to 10 mL/L, and the relative error was less than 5% for low concentration sample testing. For H 2 , HD and D 2 , the retention times can be shortened to 39, 46 and 60 s, respectively. The limits of detection were reduced to 0.046, 0.067 and 0.072 mL/L, respectively. Compared with conventional packed column, capillary packed column had sharper peak form, higher separation degree of adjacent components, shorter retention time and lower detection limits. The above results indicate that the capillary packed column with TCD detector can be used for fast detection of low concentration of hydrogen isotopes and their online analysis.

  17. QSPR models for predicting generator-column-derived octanol/water and octanol/air partition coefficients of polychlorinated biphenyls.

    Science.gov (United States)

    Yuan, Jintao; Yu, Shuling; Zhang, Ting; Yuan, Xuejie; Cao, Yunyuan; Yu, Xingchen; Yang, Xuan; Yao, Wu

    2016-06-01

    Octanol/water (K(OW)) and octanol/air (K(OA)) partition coefficients are two important physicochemical properties of organic substances. In current practice, K(OW) and K(OA) values of some polychlorinated biphenyls (PCBs) are measured using generator column method. Quantitative structure-property relationship (QSPR) models can serve as a valuable alternative method of replacing or reducing experimental steps in the determination of K(OW) and K(OA). In this paper, two different methods, i.e., multiple linear regression based on dragon descriptors and hologram quantitative structure-activity relationship, were used to predict generator-column-derived log K(OW) and log K(OA) values of PCBs. The predictive ability of the developed models was validated using a test set, and the performances of all generated models were compared with those of three previously reported models. All results indicated that the proposed models were robust and satisfactory and can thus be used as alternative models for the rapid assessment of the K(OW) and K(OA) of PCBs. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. European analytical column No. 36 from the Division of Analytical Chemistry (DAC) of the European Association for Chemical and Molecular Sciences (EuCheMS)

    DEFF Research Database (Denmark)

    Karlberg, Bo; Emons, Hendrik; Andersen, Jens Enevold Thaulov

    2008-01-01

    European analytical column no. 36 from the division of analytical chemistry (DAC) of the European association for chemical and molecular sciences (EuCheMS)......European analytical column no. 36 from the division of analytical chemistry (DAC) of the European association for chemical and molecular sciences (EuCheMS)...

  19. Prediction model for exhausted point of ion exchange resin column of moderator purification circuit at Korean CANDU plant

    International Nuclear Information System (INIS)

    Sohn, Wook; Kang, Duck-Won; Ahn, Hyun Kyoung; Rhee, In Hyoung

    2005-01-01

    Most of the carbon-14 produced at CANDU plants are removed by an Ion eXchange (IX) resin column of the moderator purification circuit, and a column is replaced based on an empirical guideline. Since the amount of carbon-14 released from CANDU plants is governed by the performance of a column, optimal operation of IX resin columns through the timely replacement based on an objective criterion is very important. For this, the model for predicting the exhausted point of an IX resin column has been developed based on local chemical equilibrium. The performance evaluation at Wolsong Unit 3 showed that the model was able to simulate the removal of species by an IX resin column to such a high degree that the model could provide an objective criterion to replace an IX resin column timely. The derived maximum service time of a fresh IX resin column was 4,080 h, about twice that of the existing empirical guideline (up to 2,000h). Accordingly, if the maximum service time derived in this paper is applied to Wolsong Unit 3, it is expected to reduce the cost needed for the replacement of IX resin column by about 50%. (author)

  20. Estimating daily surface NO2 concentrations from satellite data - a case study over Hong Kong using land use regression models

    Science.gov (United States)

    Anand, Jasdeep S.; Monks, Paul S.

    2017-07-01

    Land use regression (LUR) models have been used in epidemiology to determine the fine-scale spatial variation in air pollutants such as nitrogen dioxide (NO2) in cities and larger regions. However, they are often limited in their temporal resolution, which may potentially be rectified by employing the synoptic coverage provided by satellite measurements. In this work a mixed-effects LUR model is developed to model daily surface NO2 concentrations over the Hong Kong SAR during the period 2005-2015. In situ measurements from the Hong Kong Air Quality Monitoring Network, along with tropospheric vertical column density (VCD) data from the OMI, GOME-2A, and SCIAMACHY satellite instruments were combined with fine-scale land use parameters to provide the spatiotemporal information necessary to predict daily surface concentrations. Cross-validation with the in situ data shows that the mixed-effects LUR model using OMI data has a high predictive power (adj. R2 = 0. 84), especially when compared with surface concentrations derived using the MACC-II reanalysis model dataset (adj. R2 = 0. 11). Time series analysis shows no statistically significant trend in NO2 concentrations during 2005-2015, despite a reported decline in NOx emissions. This study demonstrates the utility in combining satellite data with LUR models to derive daily maps of ambient surface NO2 for use in exposure studies.

  1. Evaluation of reported NOx emission trends between 2005 and 2013 by assimilation of OMI-NO2 data into LOTOS-EUROS

    Science.gov (United States)

    Schaap, Martijn; Segers, Arjo; Curier, Lyana; Timmermans, Renske

    2016-04-01

    Consistent and long time series of remotely sensed trace gas levels may provide a useful tool to estimate surface emissions and emission trends. We use the OMI-NO2 product in conjunction with the LOTOS-EUROS CTM to estimate European emission trends through correction of the OMI-time series for meteorological variability as well as through assimilation using an ensemble kalman filter system (EnKF). The chemistry transport model captures a large fraction of the variability in NO2 columns at a synoptic timescale, although a seasonal signal in the bias between the modeled and retrieved column data remains. Prior to the assimilation, the OMI-NO2 data have been analyzed to establish the spatially variable temporal and spatial correlation lengths, required for the settings in the EnKF system. The assimilation run for 2005-2013 was performed using constant 2005 emissions to be able to quantify the emission change. The assimilation reduces the model-observation differences considerably. Significant negative trends of 2-3 % per year (as compared to 2005) were found in highly industrialized areas across Western Europe. The assimilation system also identifies the areas with major emission reductions in e.g. northern Spain as identified in earlier studies. Comparison of the trends derived from the assimilation and the data itself shows a high level of agreement, both the trends found in this way are smaller than those reported.

  2. Towards Improving Satellite Tropospheric NO2 Retrieval Products: Impacts of the spatial resolution and lighting NOx production from the a priori chemical transport model

    Science.gov (United States)

    Smeltzer, C. D.; Wang, Y.; Zhao, C.; Boersma, F.

    2009-12-01

    Polar orbiting satellite retrievals of tropospheric nitrogen dioxide (NO2) columns are important to a variety of scientific applications. These NO2 retrievals rely on a priori profiles from chemical transport models and radiative transfer models to derive the vertical columns (VCs) from slant columns measurements. In this work, we compare the retrieval results using a priori profiles from a global model (TM4) and a higher resolution regional model (REAM) at the OMI overpass hour of 1330 local time, implementing the Dutch OMI NO2 (DOMINO) retrieval. We also compare the retrieval results using a priori profiles from REAM model simulations with and without lightning NOx (NO + NO2) production. A priori model resolution and lightning NOx production are both found to have large impact on satellite retrievals by altering the satellite sensitivity to a particular observation by shifting the NO2 vertical distribution interpreted by the radiation model. The retrieved tropospheric NO2 VCs may increase by 25-100% in urban regions and be reduced by 50% in rural regions if the a priori profiles from REAM simulations are used during the retrievals instead of the profiles from TM4 simulations. The a priori profiles with lightning NOx may result in a 25-50% reduction of the retrieved tropospheric NO2 VCs compared to the a priori profiles without lightning. As first priority, a priori vertical NO2 profiles from a chemical transport model with a high resolution, which can better simulate urban-rural NO2 gradients in the boundary layer and make use of observation-based parameterizations of lightning NOx production, should be first implemented to obtain more accurate NO2 retrievals over the United States, where NOx source regions are spatially separated and lightning NOx production is significant. Then as consequence of a priori NO2 profile variabilities resulting from lightning and model resolution dynamics, geostationary satellite, daylight observations would further promote the next

  3. Laboratory-Scale Column Testing Using IONSIV IE-911 for Removing Cesium from Acidic Tank Waste Simulant. 2: Determination of Cesium Exchange Capacity and Effective Mass Transfer Coefficient from a 500-cm3 Column Experiment

    International Nuclear Information System (INIS)

    T.J. Tranter; R.D. Tillotson; T.A. Todd

    2005-01-01

    A semi-scale column test was performed using a commercial form of crystalline silicotitanate (CST) for removing radio-cesium from a surrogate acidic tank solution, which represents liquid waste stored at the Idaho National Engineering and Environmental Laboratory (INEEL). The engineered form of CST ion exchanger, known as IONSIVtmIE-911 (UOP, Mt. Laurel, NJ, USA), was tested in a 500-cm3 column to obtain a cesium breakthrough curve. The cesium exchange capacity of this column matched that obtained from previous testing with a 15-mc3 column. A numerical algorithm using implicit finite difference approximations was developed to solve the governing mass transport equations for the CST columns. An effective mass transfer coefficient was derived from solving these equations for previously reported 15 cm3 tests. The effective mass transfer coefficient was then used to predict the cesium breakthrough curve for the 500-cm3 column and compared to the experimental data reported in this paper. The calculated breakthrough curve showed excellent agreement with the data from the 500-cm3 column even though the interstitial velocity was a factor of two greater. Thus, this approach should provide a reasonable method for scale up to larger columns for treating actual tank waste

  4. Measurements of Nitrogen Dioxide Total Column Amounts using a Brewer Double Spectrophotometer in Direct Sun Mode

    Science.gov (United States)

    Cede, Alexander; Herman, Jay; Richter, Andreas; Krotkov, Nickolay; Burrows, John

    2006-01-01

    NO2 column amounts were measured for the past 2 years at Goddard Space Flight Center, Greenbelt, Maryland, using a Brewer spectrometer in direct Sun mode. A new bootstrap method to calibrate the instrument is introduced and described. This technique selects the cleanest days from the database to obtain the solar reference spectrum. The main advantage for direct Sun measurements is that the conversion uncertainty from slant column to vertical column is negligible compared to the standard scattered light observations where it is typically on the order of 100% (2sigma) at polluted sites. The total 2sigma errors of the direct Sun retrieved column amounts decrease with solar zenith angle and are estimated at 0.2 to 0.6 Dobson units (DU, 1 DU approx. equal to 2.7 10(exp 16) molecules cm(exp -2)), which is more accurate than scattered light measurements for high NO2 amounts. Measured NO2 column amounts, ranging from 0 to 3 DU with a mean of 0.7 DU, show a pronounced daily course and a strong variability from day to day. The NO2 concentration typically increases from sunrise to noon. In the afternoon it decreases in summer and stays constant in winter. As expected from the anthropogenic nature of its source, NO2 amounts on weekends are significantly reduced. The measurements were compared to satellite retrievals from Scanning Image Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY). Satellite data give the same average NO2 column and show a seasonal cycle that is similar to the ground data in the afternoon. We show that NO2 must be considered when retrieving aerosol absorption properties, especially for situations with low aerosol optical depth.

  5. Flooding and mass transfer in Goodloe-packed columns, Part 2

    International Nuclear Information System (INIS)

    Ayala, J.S.; Brian, B.W.; Sharon, A.C.

    1977-01-01

    Krypton gas is recovered from HTGR off-gas streams by countercurrent absorption in liquid carbon dioxide. Goodloe stainless steel wire mesh packing was chosen for the absorption columns since the process operates at -20 0 C and about 20 atm pressure. Flooding points and an overall mass transfer coefficient for Goodloe-packed columns were determined with a carbon dioxide-air-water system for 6.4 and 15.2-cm-ID columns. Flood points were obtained for liquid-to-gas mass velocity ratios of 20 to 800. A mixing model, assuming plug flow for the gas and dispersed flow for the liquid, was used to calculate an overall mass transfer coefficient, K/sub L/a. K/sub L/a, based on mass concentrations, ranged from 0.01 to 0.08 sec/sup -T/ and was found to increase with increasing liquid flow rate

  6. Processing watershed-derived nitrogen in a well-flushed New England estuary

    Science.gov (United States)

    Tobias, C.R.; Cieri, M.; Peterson, B.J.; Deegan, Linda A.; Vallino, J.; Hughes, J.

    2003-01-01

    Isotopically labeled nitrate (15NO3-) was added continuously to the Rowley estuary, Massachusetts, for 22 d to assess the transport, uptake, and cycling of terrestrially derived nitrogen during a period of high river discharge and low phytoplankton activity. Isotopic enrichment of the 3.5-km tidal prism (150,000 m3) was achieved for the 3 weeks and allowed us to construct a nitrogen mass balance model for the upper estuary. Mean ??15NO3- in the estuary ranged from 300??? to 600???, and approximately 75%-80% of the 15N was exported conservatively as 15NO 3- to the coastal ocean. Essentially all of the 20%-25% of the 15N processed in the estuary occurred in the benthos and was evenly split between direct denitrification and autotrophic assimilation. The lack of water-column 15N uptake was attributed to low phytoplankton stocks and short water residence times (1.2-1.4 d). Uptake of water-column NO3- by benthic autotrophs (enriched in excess of 100???) was a function of NO3- concentration and satisfied up to 15% and 25% of the total nitrogen demand for benthic microalgae and macroalgae, respectively. Approximately 10% of tracer assimilated by benthic autotrophs was mineralized and released back to the water column as 15NH4+. By the end of the study, 15N storage in sediments and marsh macrophytes accounted for 50%-70% of the 15N assimilated in the estuary. These compartments may sequester watershed-derived nitrogen in the estuary for time scales of months to years.

  7. Column CO2 Measurement From an Airborne Solid-State Double-Pulsed 2-Micron Integrated Path Differential Absorption Lidar

    Science.gov (United States)

    Singh, U. N.; Yu, J.; Petros, M.; Refaat, T. F.; Remus, R.; Fay, J.; Reithmaier, K.

    2014-01-01

    NASA LaRC is developing and integrating a double-Pulsed 2-micron direct detection IPDA lidar for CO2 column measurement from an airborne platform. The presentation will describe the development of the 2-micrometers IPDA lidar system and present the airborne measurement of column CO2 and will compare to in-situ measurement for various ground target of different reflectivity.

  8. Post column derivatisation analyses review. Is post-column derivatisation incompatible with modern HPLC columns?

    Science.gov (United States)

    Jones, Andrew; Pravadali-Cekic, Sercan; Dennis, Gary R; Shalliker, R Andrew

    2015-08-19

    Post Column derivatisation (PCD) coupled with high performance liquid chromatography or ultra-high performance liquid chromatography is a powerful tool in the modern analytical laboratory, or at least it should be. One drawback with PCD techniques is the extra post-column dead volume due to reaction coils used to enable adequate reaction time and the mixing of reagents which causes peak broadening, hence a loss of separation power. This loss of efficiency is counter-productive to modern HPLC technologies, -such as UHPLC. We reviewed 87 PCD methods published from 2009 to 2014. We restricted our review to methods published between 2009 and 2014, because we were interested in the uptake of PCD methods in UHPLC environments. Our review focused on a range of system parameters including: column dimensions, stationary phase and particle size, as well as the geometry of the reaction loop. The most commonly used column in the methods investigated was not in fact a modern UHPLC version with sub-2-micron, (or even sub-3-micron) particles, but rather, work-house columns, such as, 250 × 4.6 mm i.d. columns packed with 5 μm C18 particles. Reaction loops were varied, even within the same type of analysis, but the majority of methods employed loop systems with volumes greater than 500 μL. A second part of this review illustrated briefly the effect of dead volume on column performance. The experiment evaluated the change in resolution and separation efficiency of some weak to moderately retained solutes on a 250 × 4.6 mm i.d. column packed with 5 μm particles. The data showed that reaction loops beyond 100 μL resulted in a very serious loss of performance. Our study concluded that practitioners of PCD methods largely avoid the use of UHPLC-type column formats, so yes, very much, PCD is incompatible with the modern HPLC column. Copyright © 2015. Published by Elsevier B.V.

  9. Enantioseparation of dansyl amino acids by HPLC on a monolithic column dynamically coated with a vancomycin derivative.

    Science.gov (United States)

    Pittler, Elfriede; Schmid, Martin G

    2010-11-01

    In this work a chiral stationary phase was prepared by dynamically coating a monolithic reversed-phase HPLC column with a vancomycin-derivative as chiral selector. A hydrophobic alkyl-chain was attached to the vancomycin molecule, providing the immobilization of the chiral selector on the reversed-phase material. Dansyl amino acids were chosen as model analytes for testing the separation power of the dynamically coated phase. All investigated compounds were separated into their enantiomers. Compared with a conventionally packed vancomycin-CSP, a reversal of the enantiomer elution order was obtained. Copyright © 2010 John Wiley & Sons, Ltd.

  10. DAF-fluorescence without NO: elicitor treated tobacco cells produce fluorescing DAF-derivatives not related to DAF-2 triazol.

    Science.gov (United States)

    Rümer, Stefan; Krischke, Markus; Fekete, Agnes; Mueller, Martin J; Kaiser, Werner M

    2012-08-15

    Diaminofluorescein-dyes (DAFs) are widely used for visualizing NO· production in biological systems. Here it was examined whether DAF-fluorescence could be evoked by other means than nitrosation. Tobacco (Nicotiana tabacum) suspension cells treated with the fungal elicitor cryptogein released compound(s) which gave a fluorescence increase in the cell-free filtrate after addition of DAF-2 or DAF-FM or DAR-4M. DAF-reactive compounds were relatively stable and identified as reaction products of H(2)O(2) plus apoplastic peroxidase (PO). CPTIO prevented formation of these products. Horseradish-peroxidase (HR-PO) plus H(2)O(2) also generated DAF-fluorescence in vitro. Using RP-HPLC with fluorescence detection, DAF derivatives were further analyzed. In filtrates from cryptogein-treated cells, fluorescence originated from two novel DAF-derivatives also obtained in vitro with DAF-2+HR-PO+H(2)O(2). DAF-2T was only detected when an NO donor (DEA-NO) was present. Using high resolution mass spectrometry, the two above-described novel DAF-reaction products were tentatively identified as dimers. In cells preloaded with DAF-2 DA and incubated with or without cryptogein, DAF-fluorescence originated from a complex pattern of multiple products different from those obtained in vitro. One specific peak was responsive to exogenous H(2)O(2), and another, minor peak eluted at or close to DAF-2T. Thus, in contrast to the prevailing opinion, DAF-2 can be enzymatically converted into a variety of highly fluorescing derivatives, both inside and outside cells, of which none (outside) or only a minor part (inside) appeared NO· dependent. Accordingly, DAF-fluorescence and its prevention by cPTIO do not necessarily indicate NO· production. Copyright © 2012 Elsevier Inc. All rights reserved.

  11. Thermal neutron flux distribution in ET-RR-2 reactor thermal column

    Directory of Open Access Journals (Sweden)

    Imam Mahmoud M.

    2002-01-01

    Full Text Available The thermal column in the ET-RR-2 reactor is intended to promote a thermal neutron field of high intensity and purity to be used for following tasks: (a to provide a thermal neutron flux in the neutron transmutation silicon doping, (b to provide a thermal flux in the neutron activation analysis position, and (c to provide a thermal neutron flux of high intensity to the head of one of the beam tubes leading to the room specified for boron thermal neutron capture therapy. It was, therefore, necessary to determine the thermal neutron flux at above mentioned positions. In the present work, the neutron flux in the ET-RR-2 reactor system was calculated by applying the three dimensional diffusion depletion code TRITON. According to these calculations, the reactor system is composed of the core, surrounding external irradiation grid, beryllium block, thermal column and the water reflector in the reactor tank next to the tank wall. As a result of these calculations, the thermal neutron fluxes within the thermal column and at irradiation positions within the thermal column were obtained. Apart from this, the burn up results for the start up core calculated according to the TRITION code were compared with those given by the reactor designer.

  12. Multiscale observations of CO2, 13CO2, and pollutants at Four Corners for emission verification and attribution

    Science.gov (United States)

    Lindenmaier, Rodica; Dubey, Manvendra K.; Henderson, Bradley G.; Butterfield, Zachary T.; Herman, Jay R.; Rahn, Thom; Lee, Sang-Hyun

    2014-01-01

    There is a pressing need to verify air pollutant and greenhouse gas emissions from anthropogenic fossil energy sources to enforce current and future regulations. We demonstrate the feasibility of using simultaneous remote sensing observations of column abundances of CO2, CO, and NO2 to inform and verify emission inventories. We report, to our knowledge, the first ever simultaneous column enhancements in CO2 (3–10 ppm) and NO2 (1–3 Dobson Units), and evidence of δ13CO2 depletion in an urban region with two large coal-fired power plants with distinct scrubbing technologies that have resulted in ∆NOx/∆CO2 emission ratios that differ by a factor of two. Ground-based total atmospheric column trace gas abundances change synchronously and correlate well with simultaneous in situ point measurements during plume interceptions. Emission ratios of ∆NOx/∆CO2 and ∆SO2/∆CO2 derived from in situ atmospheric observations agree with those reported by in-stack monitors. Forward simulations using in-stack emissions agree with remote column CO2 and NO2 plume observations after fine scale adjustments. Both observed and simulated columnNO2/∆CO2 ratios indicate that a large fraction (70–75%) of the region is polluted. We demonstrate that the column emission ratios of ∆NO2/∆CO2 can resolve changes from day-to-day variation in sources with distinct emission factors (clean and dirty power plants, urban, and fires). We apportion these sources by using NO2, SO2, and CO as signatures. Our high-frequency remote sensing observations of CO2 and coemitted pollutants offer promise for the verification of power plant emission factors and abatement technologies from ground and space. PMID:24843169

  13. Thermally stable dexsil-400 glass capillary columns

    International Nuclear Information System (INIS)

    Maskarinec, M.P.; Olerich, G.

    1980-01-01

    The factors affecting efficiency, thermal stability, and reproducibility of Dexsil-400 glass capillary columns for gas chromatography in general, and for polycyclic aromatic hydrocarbons (PAHs) in particular were investigated. Columns were drawn from Kimble KG-6 (soda-lime) glass or Kimox (borosilicate) glass. All silylation was carried out at 200 0 C. Columns were coated according to the static method. Freshly prepared, degassed solutions of Dexsil-400 in pentane or methylene chloride were used. Thermal stability of the Dexsil 400 columns with respect to gas chromatography/mass spectrometry (GC/MS) were tested. Column-to-column variability is a function of each step in the fabrication of the columns. The degree of etching, extent of silylation, and stationary phase film thickness must be carefully controlled. The variability in two Dexsil-400 capillary column prepared by etching, silylation with solution of hexa methyl disilazone (HMDS), and static coating is shown and also indicates the excellent selectivity of Dexsil-400 for the separation of alkylated aromatic compounds. The wide temperature range of Dexsil-400 and the high efficiency of the capillary columns also allow the analysis of complex mixtures with minimal prefractionation. Direct injection of a coal liquefaction product is given. Analysis by GC/MS indicated the presence of parent PAHs, alkylated PAHs, nitrogen and sulfur heterocycles, and their alkylated derivatives. 4 figures

  14. Simultaneous determination of palladium, platinum and rhodium by on-line column enrichment and HPLC with 2,4-dihydroxybenzylidenethiorhodanine as pre-column derivatization reagent

    Directory of Open Access Journals (Sweden)

    Dong Xuechang

    2006-01-01

    Full Text Available A new method for the simultaneous determination of palladium, platinum and rhodium ions as metal-DHBTR chelates was developed. The palladium, platinum and rhodium ions were pre-column derivatized with 2,4-dihydroxybenzylidenethiorhodanine (DHBTR to form colored chelates. The Pd-DHBTR, Pt-DHBTR and Rh-DHBTR chelates can be absorbed onto the front of the enrichment column when they were injected into the injector and sent to the enrichment column with a 0.05 mol L-1 sodium acetate-acetic acid buffer solution (pH 3.5 as mobile phase. After the enrichment had finished, by switching the six ports switching valve, the retained chelates were back-flushed by mobile phase and traveling towards the analytical column. These chelates separation on the analytical column was satisfactory with 62% (v/v acetonitrile (containing 0.05 mol L-1 of pH 3.5 sodium acetate-acetic acid buffer salt and 0.1% (m/v of tritonX-100 as mobile phase. The Limits of detection of palladium, platinum and rhodium are 3.6 ng L-1, 3.2 ng L-1 and 4.5 ng L-1, respectively. This method was applied to the determination of palladium, platinum and rhodium in water, urine and soil samples with good results.

  15. Airborne Measurements of CO2 Column Concentration and Range Using a Pulsed Direct-Detection IPDA Lidar

    Science.gov (United States)

    Abshire, James B.; Ramanathan, Anand; Riris, Haris; Mao, Jianping; Allan, Graham R.; Hasselbrack, William E.; Weaver, Clark J.; Browell, Edward V.

    2013-01-01

    We have previously demonstrated a pulsed direct detection IPDA lidar to measure range and the column concentration of atmospheric CO2. The lidar measures the atmospheric backscatter profiles and samples the shape of the 1,572.33 nm CO2 absorption line. We participated in the ASCENDS science flights on the NASA DC-8 aircraft during August 2011 and report here lidar measurements made on four flights over a variety of surface and cloud conditions near the US. These included over a stratus cloud deck over the Pacific Ocean, to a dry lake bed surrounded by mountains in Nevada, to a desert area with a coal-fired power plant, and from the Rocky Mountains to Iowa, with segments with both cumulus and cirrus clouds. Most flights were to altitudes >12 km and had 5-6 altitude steps. Analyses show the retrievals of lidar range, CO2 column absorption, and CO2 mixing ratio worked well when measuring over topography with rapidly changing height and reflectivity, through thin clouds, between cumulus clouds, and to stratus cloud tops. The retrievals shows the decrease in column CO2 due to growing vegetation when flying over Iowa cropland as well as a sudden increase in CO2 concentration near a coal-fired power plant. For regions where the CO2 concentration was relatively constant, the measured CO2 absorption lineshape (averaged for 50 s) matched the predicted shapes to better than 1% RMS error. For 10 s averaging, the scatter in the retrievals was typically 2-3 ppm and was limited by the received signal photon count. Retrievals were made using atmospheric parameters from both an atmospheric model and from in situ temperature and pressure from the aircraft. The retrievals had no free parameters and did not use empirical adjustments, and >70% of the measurements passed screening and were used in analysis. The differences between the lidar-measured retrievals and in situ measured average CO2 column concentrations were 6 km.

  16. Gas Chromatograph Method Optimization Trade Study for RESOLVE: 20-meter Column v. 8-meter Column

    Science.gov (United States)

    Huz, Kateryna

    2014-01-01

    RESOLVE is the payload on a Class D mission, Resource Prospector, which will prospect for water and other volatile resources at a lunar pole. The RESOLVE payload's primary scientific purpose includes determining the presence of water on the moon in the lunar regolith. In order to detect the water, a gas chromatograph (GC) will be used in conjunction with a mass spectrometer (MS). The goal of the experiment was to compare two GC column lengths and recommend which would be best for RESOLVE's purposes. Throughout the experiment, an Inficon Fusion GC and an Inficon Micro GC 3000 were used. The Fusion had a 20m long column with 0.25mm internal diameter (Id). The Micro GC 3000 had an 8m long column with a 0.32mm Id. By varying the column temperature and column pressure while holding all other parameters constant, the ideal conditions for testing with each column length in their individual instrument configurations were determined. The criteria used for determining the optimal method parameters included (in no particular order) (1) quickest run time, (2) peak sharpness, and (3) peak separation. After testing numerous combinations of temperature and pressure, the parameters for each column length that resulted in the most optimal data given my three criteria were selected. The ideal temperature and pressure for the 20m column were 95 C and 50psig. At this temperature and pressure, the peaks were separated and the retention times were shorter compared to other combinations. The Inficon Micro GC 3000 operated better at lower temperature mainly due to the shorter 8m column. The optimal column temperature and pressure were 70 C and 30psig. The Inficon Micro GC 3000 8m column had worse separation than the Inficon Fusion 20m column, but was able to separate water within a shorter run time. Therefore, the most significant tradeoff between the two column lengths was peak separation of the sample versus run time. After performing several tests, it was concluded that better

  17. NO2 and HCHO variability in Mexico City from MAX-DOAS measurements

    Science.gov (United States)

    Grutter, M.; Friedrich, M. M.; Rivera, C. I.; Arellano, E. J.; Stremme, W.

    2015-12-01

    Atmospheric studies in large cities are of great relevance since pollution affects air quality and human health. A network of Multi Axis Differential Optical Absorption Spectrometers (MAX-DOAS) has been established in strategic sites within the Mexico City metropolitan area. Four instruments are now in operation with the aim to study the variability and spatial distribution of key pollutants, providing results of O4, NO2 and HCHO slant column densities (SCD). A numerical code has been written to retrieve gas profiles of NO2 and HCHO using radiative transfer simulations. We present the first results of the variability of these trace gases which will bring new insight in the current knowledge of transport patterns, emissions as well as frequency and origin of extraordinary events. Results of the vertical column densities (VCD) valiability of NO2 and HCHO in Mexico City are presented. These studies are useful to validate current and future satellite observatopns such as OMI, TROPOMI and TEMPO.

  18. Denitrification in the water column of the central Baltic Sea

    DEFF Research Database (Denmark)

    Dalsgaard, Tage; De Brabandere, Loreto; Hall, Per O. J.

    2013-01-01

    Removal of fixed nitrogen in the water column of the eastern Gotland Basin, central Baltic Sea, was studied during two cruises in September 2008 and August 2010. The water column was stratified with anoxic sulfidic bottom water meeting oxic nitrate containing water at the oxic–anoxic interface......3 or sulfide concentrations were converted to in situ rates using the measured water column concentrations of NO3 and sulfide and the actual measured relations between NO3 and sulfide concentrations and enitrification rates. In situ denitrification ranged from 0.24 to 15.9 nM N2 h1. Assuming...... area. Even with an active denitrification layer of 3–6 m thickness the pelagic denitrification per unit area clearly exceeded sediment denitrification rates elsewhere in the Baltic Sea. When extrapolated to the entire Baltic Proper (BP) denitrification in the water column was in the range of 132...

  19. Commissioning and operation of distillation column at Madras Atomic Power Station (Paper No. 1.10)

    International Nuclear Information System (INIS)

    Neelakrishnan, G.; Subramanian, N.

    1992-01-01

    In Madras Atomic Power Station (MAPS), an upgrading plant based on vacuum distillation was constructed to upgrade the downgraded heavy water collected in vapor recovery dryers. There are two distillation columns and each having a capacity of 77.5 tonne per annum of reactor grade heavy water with average feed concentration of 30% IP. The performance of the distillation columns has been very good. The column I and column II have achieved an operating factor of 92% and 90% respectively. The commissioning activities, and subsequent improvements carried out in the distillation columns are described. (author)

  20. Comparative study of the performance of columns packed with several new fine silica particles. Would the external roughness of the particles affect column properties?

    Science.gov (United States)

    Gritti, Fabrice; Guiochon, Georges

    2007-09-28

    We measured and compared the characteristics and performance of columns packed with particles of five different C(18)-bonded silica, 3 and 5 microm Luna, 3 microm Atlantis, 3.5 microm Zorbax, and 2.7 microm Halo. The average particle size of each material was derived from the SEM pictures of 200 individual particles. These pictures contrast the irregular morphology of the external surface of the Zorbax and Halo particles and the smooth surface of the Luna and Atlantis particles. In a wide range of mobile phase velocities (from 0.010 to 3 mL/min) and at ambient temperature, we measured the first and second central moments of the peaks of naphthalene, insulin, and bovine serum albumin (BSA). These moments were corrected for the contributions of the extra-column volumes to calculate the reduced HETPs. The C-terms of naphthalene and insulin are largest for the Halo and Zorbax materials and the A-term smallest for the Halo-packed column. The Halo column performs the best for the low molecular weight compound naphthalene (minimum reduced HETP, 1.4) but is not as good as the Atlantis or Luna columns for the large molecular weight compound insulin. The Zorbax column is the least efficient column because of its large C-term. The lowest sample diffusivity through these particles, alone, does not account for the results. It is most likely that the roughness of the external surface of the Halo and Zorbax particles limit the performance of these columns at high flow rates generating an unusually high film mass transfer resistance.

  1. Aerosols correction of the OMI tropospheric NO2 retrievals over cloud-free scenes: Different methodologies based on the O2-O2 477 nm band

    Science.gov (United States)

    Chimot, Julien; Vlemmix, Tim; Veefkind, Pepijn; Levelt, Pieternel

    2016-04-01

    Numerous studies have drawn attention to the complexities related to the retrievals of tropospheric NO2 columns derived from satellite UltraViolet-Visible (UV-Vis) measurements in the presence of aerosols. Correction for aerosol effects will remain a challenge for the next generation of air quality satellite instruments such as TROPOMI on Sentinel-5 Precursor, Sentinel-4 and Sentinel-5. The Ozone Monitoring Instrument (OMI) instrument has provided daily global measurements of tropospheric NO2 for more than a decade. However, aerosols are not explicitly taken into account in the current operational OMI tropospheric NO2 retrieval chain (DOMINO v2 [Boersma et al., 2011]). Our study analyses 2 approaches for an operational aerosol correction, based on the use of the O2-O2 477 nm band. The 1st approach is the cloud-model based aerosol correction, also named "implicit aerosol correction", and already used in the operational chain. The OMI O2-O2 cloud retrieval algorithm, based on the Differential Optical Absorption Spectroscopy (DOAS) approach, is applied both to cloudy and to cloud-free scenes with aerosols present. Perturbation of the OMI cloud retrievals over scenes dominated by aerosols has been observed in recent studies led by [Castellanos et al., 2015; Lin et al., 2015; Lin et al., 2014]. We investigated the causes of these perturbations by: (1) confronting the OMI tropospheric NO2, clouds and MODIS AQUA aerosol products; (2) characterizing the key drivers of the aerosol net effects, compared to a signal from clouds, in the UV-Vis spectra. This study has focused on large industrialised areas like East-China, over cloud-free scenes. One of the key findings is the limitation due to the coarse sampling of the employed cloud Look-Up Table (LUT) to convert the results of the applied DOAS fit into effective cloud fraction and pressure. This leads to an underestimation of tropospheric NO2 amount in cases of particles located at elevated altitude. A higher sampling of the

  2. Geophysical validation and long-term consistency between GOME-2/MetOp-A total ozone column and measurements from the sensors GOME/ERS-2, SCIAMACHY/ENVISAT and OMI/Aura

    Directory of Open Access Journals (Sweden)

    M. E. Koukouli

    2012-09-01

    Full Text Available The main aim of the paper is to assess the consistency of five years of Global Ozone Monitoring Experiment-2/Metop-A [GOME-2] total ozone columns and the long-term total ozone satellite monitoring database already in existence through an extensive inter-comparison and validation exercise using as reference Brewer and Dobson ground-based measurements. The behaviour of the GOME-2 measurements is being weighed against that of GOME (1995–2011, Ozone Monitoring Experiment [OMI] (since 2004 and the Scanning Imaging Absorption spectroMeter for Atmospheric CartograpHY [SCIAMACHY] (since 2002 total ozone column products. Over the background truth of the ground-based measurements, the total ozone columns are inter-evaluated using a suite of established validation techniques; the GOME-2 time series follow the same patterns as those observed by the other satellite sensors. In particular, on average, GOME-2 data underestimate GOME data by about 0.80%, and underestimate SCIAMACHY data by 0.37% with no seasonal dependence of the differences between GOME-2, GOME and SCIAMACHY. The latter is expected since the three datasets are based on similar DOAS algorithms. This underestimation of GOME-2 is within the uncertainty of the reference data used in the comparisons. Compared to the OMI sensor, on average GOME-2 data underestimate OMI_DOAS (collection 3 data by 1.28%, without any significant seasonal dependence of the differences between them. The lack of seasonality might be expected since both the GOME data processor [GDP] 4.4 and OMI_DOAS are DOAS-type algorithms and both consider the variability of the stratospheric temperatures in their retrievals. Compared to the OMI_TOMS (collection 3 data, no bias was found. We hence conclude that the GOME-2 total ozone columns are well suitable to continue the long-term global total ozone record with the accuracy needed for climate monitoring studies.

  3. HPLC separation of triacylglycerol positional isomers on a polymeric ODS column.

    Science.gov (United States)

    Kuroda, Ikuma; Nagai, Toshiharu; Mizobe, Hoyo; Yoshimura, Nobuhito; Gotoh, Naohiro; Wada, Shun

    2008-07-01

    A polymeric ODS column was applied to the resolution of triacylglycerol positional isomers (TAG-PI), i.e. 1,3-dioleoyl-2-palmitoyl-glycerol (OPO) and 1,2-dioleoyl-3-palmitoyl-rac-glycerol (OOP), with a recycle HPLC system. To investigate the ODS column species and the column temperatures for the resolution of a TAG-PI pair, a mixture of OPO and OOP was subjected to an HPLC system equipped with a non-endcapped polymeric, endcapped monomeric, endcapped intermediate, or non-endcapped monomeric ODS column at three different column temperatures (40, 25, or 10 degrees C). Only the non-endcapped polymeric ODS column achieved the separation of OPO and OOP, and the lowest column temperature (10 degrees C) showed the best resolution for them. The other pair of TAG-PI, a mixture of 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) and 1,2-dipalmitoyl-3-oleoyl-rac-glycerol (PPO) was also subjected to the system equipped with a non-endcapped polymeric or monomeric ODS column at five different column temperatures (40, 32, 25, 17, and 10 degrees C). Thus, POP and PPO were also separated on only the non-endcapped polymeric ODS column at 25 degrees C. However, no clear peak appeared at 10 degrees C. These results would indicate that the polymeric ODS stationary phase has an ability to recognize the structural differences between TAG-PI pairs. Also, the column temperature is a very important factor for separating the TAG-PI pair, and the optimal temperature would relate to the solubility of TAG-PI in the mobile phase. Furthermore, the recycle HPLC system provided measurements for the separation and analysis of TAG-PI pairs.

  4. Visualization of NO2 emission sources using temporal and spatial pattern analysis in Asia

    Science.gov (United States)

    Schütt, A. M. N.; Kuhlmann, G.; Zhu, Y.; Lipkowitsch, I.; Wenig, M.

    2016-12-01

    Nitrogen dioxide (NO2) is an indicator for population density and level of development, but the contributions of the different emission sources to the overall concentrations remains mostly unknown. In order to allocate fractions of OMI NO2 to emission types, we investigate several temporal cycles and regional patterns.Our analysis is based on daily maps of tropospheric NO2 vertical column densities (VCDs) from the Ozone Monitoring Instrument (OMI). The data set is mapped to a high resolution grid by a histopolation algorithm. This algorithm is based on a continuous parabolic spline, producing more realistic smooth distributions while reproducing the measured OMI values when integrating over ground pixel areas.In the resulting sequence of zoom in maps, we analyze weekly and annual cycles for cities, countryside and highways in China, Japan and Korea Republic and look for patterns and trends and compare the derived results to emission sources in Middle Europe and North America. Due to increased heating in winter compared to summer and more traffic during the week than on Sundays, we dissociate traffic, heating and power plants and visualized maps with different sources. We will also look into the influence of emission control measures during big events like the Olympic Games 2008 and the World Expo 2010 as a possibility to confirm our classification of NO2 emission sources.

  5. The physical properties of giant molecular cloud complexes in the outer Galaxy - Implications for the ratio of H2 column density to (C-12)O intensity

    Science.gov (United States)

    Sodroski, T. J.

    1991-01-01

    The physical properties of 35 giant molecular cloud complexes in the outer Galaxy were derived from the Goddard-Columbia surveys of the Galactic plane region (Dame et al., 1987). The spatial and radial velocity boundaries for the individual cloud complexes were estimated by analyzing the spatial and velocity structure of emission features in the (C-12)O surveys, and the distance to each cmplex was determined kinematically on the assumption of a flat rotation curve. The ratio of the H2 column density to the (C-12)O intensity for the outer Galaxy complexes was found to be about 6.0 x 10 to the 20th molecules/sq cm K per km/sec, which is by a factor of 2-3 greater than the value derived by other auhtors for the inner Galaxy complexes. This increase in the H2 column density/(C-12)O intensity with the distance from with the Galactic center is consistent with predictions of the optically thick cloudlet model of giant molecular cloud complexes.

  6. Optimum pressure for total-reflux operated thermal diffusion column for isotope separation

    International Nuclear Information System (INIS)

    Yamamoto, Ichiro; Makino, Hitoshi; Kanagawa, Akira

    1990-01-01

    A formula for prediction of the optimum operating pressure P opt of the thermal diffusion columns at total reflux is derived based on the approximate formulae for the column constants which can be evaluated analytically. The formula is expressed explicitly in terms of (1) physical properties of gases to be separated, (2) ratio of radii between hot wire and cold wall of the column, and (3) the ratio of the temperature difference to the cold wall temperature. The result is compared with experimental data; (1) binary monatomic gas systems, (2) multicomponent monatomic gas systems, (3) isotopically substituted polyatomic systems, (4) systems of low atomic or molecular weight, and (5) mixtures of unlike gases; mainly obtained by Rutherford and coworkers. Although the formula is based on the rather rough approximation for the column constants, the optimum pressures predicted by the present formula are in successfully good agreement with the experimental data even for the systems of low atomic or molecular weight and that of mixtures of unlike gases. (author)

  7. Study on Predicting Axial Load Capacity of CFST Columns

    Science.gov (United States)

    Ravi Kumar, H.; Muthu, K. U.; Kumar, N. S.

    2017-11-01

    This work presents an analytical study and experimental study on the behaviour and ultimate load carrying capacity of axially compressed self-compacting concrete-filled steel tubular columns. Results of tests conducted by various researchers on 213 samples concrete-filled steel tubular columns are reported and present authors experimental data are reported. Two theoretical equations were derived for the prediction of the ultimate axial load strength of concrete-filled steel tubular columns. The results from prediction were compared with the experimental data. Validation to the experimental results was made.

  8. Comparison of atmospheric CO2 columns at high latitudes from ground-based and satellite-based methods

    Science.gov (United States)

    Jacobs, N.; Simpson, W. R.; Parker, H. A.; Tu, Q.; Blumenstock, T.; Dubey, M. K.; Hase, F.; Osterman, G. B.

    2017-12-01

    Total column measurements of carbon-dioxide (CO2) from the Orbiting Carbon Observatory-2 (OCO-2) satellite have been validated at mid-latitudes by comparison to the Total Carbon Column Observing Network (TCCON), but there are still a limited number of sites providing high-latitude validation data for satellite observations of CO2, and no TCCON sites in Alaska. To understand the global distribution of CO2 sources and sinks, it is essential that we increase the abundance of validation sites, particularly in the climate-sensitive high-latitude Boreal forest. Therefore, we began the Arctic Mobile Infrared Greenhouse Gas Observations (AMIGGO) campaign in the Boreal Forest region around Fairbanks, Alaska with the goal of satellite validation and measurement of natural ecosystem fluxes. In this campaign, we used the EM27/SUN mobile solar-viewing Fourier-transform infrared spectrometer (EM27/SUN FTS) to retrieve the total CO2 column and column-averaged dry-air mole fraction of CO2 (XCO2) with the GGG2014 algorithm. The EM27/SUN FTS was developed by the Karlsruhe Institute of Technology (KIT) in collaboration with Bruker optics (Gisi et al., 2012, doi:10.5194/amt-5-2969-2012) and has been deployed in urban areas to measure anthropogenic fluxes of CO2 and CH4. To evaluate the EM27/SUN performance, co-located observations were made with two EM27/SUN spectrometers, and we found that XCO2 differences between spectrometers were small (0.24ppm on average) and very stable over time. In this presentation, we report on 14 OCO-2 targeted overpasses that occurred from August 2016 through July 2017, along with additional targets obtained during ongoing observations in 2017. We investigate underlying reasons for observed differences between OCO-2 and ground-based XCO2 using methods developed by Wunch et al. (2017, doi:10.5194/amt-10-2209-2017). As an additional point of comparison, coincident aircraft observations by NOAA Earth System Research Laboratory (ESRL) Global Monitoring

  9. Re-evaluating the NO 2 hotspot over the South African Highveld

    Directory of Open Access Journals (Sweden)

    Alexandra S.M. Lourens

    2012-10-01

    Full Text Available Globally, numerous pollution hotspots have been identified using satellite-based instruments. One of these hotspots is the prominent NO2hotspot over the South African Highveld. The tropospheric NO2column density of this area is comparable to that observed for central and northern Europe, eastern North America and south-east Asia. The most well-known pollution source in this area is a large array of coal-fired power stations. Upon closer inspection, long-term means of satellite observations also show a smaller area, approximately 100 km west of the Highveld hotspot, with a seemingly less substantial NO2column density. This area correlates with the geographical location of the Johannesburg–Pretoria conurbation or megacity, one of the 40 largest metropolitan areas in the world. Ground-based measurements indicate that NO2concentrations in the megacity have diurnal peaks in the early morning and late afternoon, which coincide with peak traffic hours and domestic combustion. During these times, NO2concentrations in the megacity are higher than those in the Highveld hotspot. These diurnal NO2 peaks in the megacity have generally been overlooked by satellite observations because the satellites have fixed local overpass times that do not coincide with these peak periods. Consequently, the importance of NO2 over the megacity has been underestimated. We examined the diurnal cycles of NO2 ground-based measurements for the two areas – the megacity and the Highveld hotspot – and compared them with the satellite-based NO2 observations. Results show that the Highveld hotspot is accompanied by a second hotspot over the megacity, which is of significance for the more than 10 million people living in this megacity.

  10. Energy optimization and comparative study of pre- and post-fractionator extractive dividing wall column for the CO2–ethane azeotropic process

    International Nuclear Information System (INIS)

    Tavan, Yadollah; Riazi, Seiied Hadi; Nozohouri, Mostafa

    2014-01-01

    Graphical abstract: - Highlights: • Two arrangements is proposed for extractive DWC based on pre- and post- fractionator. • Operating parameters are optimized to minimize energy demand. • The pre-fractionator design showed the best performance in comparison to others. - Abstract: Two possible extractive dividing-wall column (DWC) arrangements are explored to find the potential benefits derived from thermally coupled distillations in separation of a mixture including the CO 2 –ethane azeotrope with a low boiling point. It is shown that the process including pre-fractionator in the DWC design in its optimized state leads to 51.6% reduction in total duties in comparison with the conventional process. Furthermore, a comparison between conventional extractive distillation columns and the new DWC process is made in terms of cost estimation, CO 2 removal efficiency and CO 2 emission reduction. Remarkable, the results clearly show that DWC process is interesting/feasible and the novel proposed DWC alternative reduces the steam requirements by 41% and the equipment costs by 31%

  11. CO2 Absorption from Biogas by Glycerol: Conducted in Semi-Batch Bubble Column

    Science.gov (United States)

    puji lestari, Pratiwi; Mindaryani, Aswati; Wirawan, S. K.

    2018-03-01

    Biogas is a renewable energy source that has been developed recently. The main contents of Biogas itself are Methane and carbon dioxide (CO2) where Methane is the main component of biogas with CO2 as the highest impurities. The quality of biogas depends on the CO2 content, the lower CO2 levels, the higher biogas quality. Absorption is one of the methods to reduce CO2 level. The selections of absorbent and appropriate operating parameters are important factors in the CO2 absorption from biogas. This study aimed to find out the design parameters for CO2 absorption using glycerol that represented by the overall mass transfer coefficient (KLa) and Henry’s constant (H). This study was conducted in semi-batch bubble column. Mixed gas was contacted with glycerol in a bubble column. The concentration of CO2 in the feed gas inlet and outlet columns were analysed by Gas Chromatograph. The variables observed in this study were superficial gas velocity and temperatures. The results showed that higher superficial gas velocity and lower temperature increased the rate of absorption process and the amount of CO2 absorbed.

  12. Characterization of retentivity of reversed phase liquid chromatography columns.

    Science.gov (United States)

    Ying, P T; Dorsey, J G

    1991-03-01

    There are dozens of commercially available reversed phase columns, most marketed as C-8 or C-18 materials, but with no useful way of classifying their retentivity. A useful way of ranking these columns in terms of column "strength" or retentivity is presented. The method utilizes a value for ln k'(w), the estimated retention of a solute from a mobile phase of 100% water, and the slope of the plot of ln k' vsE(T)(30), the solvent polarity. The method is validated with 26 solutes varying in ln k'(w) from about 2 to over 20, on 14 different reversed phase columns. In agreement with previous work, it is found that the phase volume ratio of the column is the most important parameter in determining retentivity. It is strongly suggested that manufacturers adopt a uniform method of calculating this value and that it be made available in advertising, rather than the uninterpretable "% carbon".

  13. Fixed-bed column adsorption of methyl blue using carbon derived ...

    African Journals Online (AJOL)

    Axle Wood Carbon (AWC) was used to study the removal of Methyl Blue (MB) from its aqueous solution in a fixed-bed column adsorption system. The adsorbent (AWC) was characterized using SEM and pHPZC. SEM revealed the surface morphology and from the pHPZC determination, it was found that at pH of 8.21 the ...

  14. Formaldehyde Column Density Measurements as a Suitable Pathway to Estimate Near-Surface Ozone Tendencies from Space

    Science.gov (United States)

    Schroeder, Jason R.; Crawford, James H.; Fried, Alan; Walega, James; Weinheimer, Andrew; Wisthaler, Armin; Mueller, Markus; Mikoviny, Tomas; Chen, Gao; Shook, Michael; hide

    2016-01-01

    In support of future satellite missions that aim to address the current shortcomings in measuring air quality from space, NASA's Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaign was designed to enable exploration of relationships between column measurements of trace species relevant to air quality at high spatial and temporal resolution. In the DISCOVER-AQ data set, a modest correlation (r2 = 0.45) between ozone (O3) and formaldehyde (CH2O) column densities was observed. Further analysis revealed regional variability in the O3-CH2O relationship, with Maryland having a strong relationship when data were viewed temporally and Houston having a strong relationship when data were viewed spatially. These differences in regional behavior are attributed to differences in volatile organic compound (VOC) emissions. In Maryland, biogenic VOCs were responsible for approx.28% of CH2O formation within the boundary layer column, causing CH2O to, in general, increase monotonically throughout the day. In Houston, persistent anthropogenic emissions dominated the local hydrocarbon environment, and no discernable diurnal trend in CH2O was observed. Box model simulations suggested that ambient CH2O mixing ratios have a weak diurnal trend (+/-20% throughout the day) due to photochemical effects, and that larger diurnal trends are associated with changes in hydrocarbon precursors. Finally, mathematical relationships were developed from first principles and were able to replicate the different behaviors seen in Maryland and Houston. While studies would be necessary to validate these results and determine the regional applicability of the O3-CH2O relationship, the results presented here provide compelling insight into the ability of future satellite missions to aid in monitoring near-surface air quality.

  15. Total ozone column derived from GOME and SCIAMACHY using KNMI retrieval algorithms: Validation against Brewer measurements at the Iberian Peninsula

    Science.gov (United States)

    Antón, M.; Kroon, M.; López, M.; Vilaplana, J. M.; Bañón, M.; van der A, R.; Veefkind, J. P.; Stammes, P.; Alados-Arboledas, L.

    2011-11-01

    This article focuses on the validation of the total ozone column (TOC) data set acquired by the Global Ozone Monitoring Experiment (GOME) and the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) satellite remote sensing instruments using the Total Ozone Retrieval Scheme for the GOME Instrument Based on the Ozone Monitoring Instrument (TOGOMI) and Total Ozone Retrieval Scheme for the SCIAMACHY Instrument Based on the Ozone Monitoring Instrument (TOSOMI) retrieval algorithms developed by the Royal Netherlands Meteorological Institute. In this analysis, spatially colocated, daily averaged ground-based observations performed by five well-calibrated Brewer spectrophotometers at the Iberian Peninsula are used. The period of study runs from January 2004 to December 2009. The agreement between satellite and ground-based TOC data is excellent (R2 higher than 0.94). Nevertheless, the TOC data derived from both satellite instruments underestimate the ground-based data. On average, this underestimation is 1.1% for GOME and 1.3% for SCIAMACHY. The SCIAMACHY-Brewer TOC differences show a significant solar zenith angle (SZA) dependence which causes a systematic seasonal dependence. By contrast, GOME-Brewer TOC differences show no significant SZA dependence and hence no seasonality although processed with exactly the same algorithm. The satellite-Brewer TOC differences for the two satellite instruments show a clear and similar dependence on the viewing zenith angle under cloudy conditions. In addition, both the GOME-Brewer and SCIAMACHY-Brewer TOC differences reveal a very similar behavior with respect to the satellite cloud properties, being cloud fraction and cloud top pressure, which originate from the same cloud algorithm (Fast Retrieval Scheme for Clouds from the Oxygen A-Band (FRESCO+)) in both the TOSOMI and TOGOMI retrieval algorithms.

  16. Three-component synthesis of C2F5-substituted pyrazoles from C2F5CH2NH2·HCl, NaNO2 and electron-deficient alkynes

    Directory of Open Access Journals (Sweden)

    Pavel K. Mykhailiuk

    2015-01-01

    Full Text Available A one-pot reaction between C2F5CH2NH2·HCl, NaNO2 and electron-deficient alkynes gives C2F5-substituted pyrazoles in excellent yields. The transformation smoothly proceeds in dichloromethane/water, tolerates the presence of air, and requires no purification of products by column chromatography. Mechanistically, C2F5CH2NH2·HCl and NaNO2 react first in water to generate C2F5CHN2, that participates in a [3 + 2] cycloaddition with electron-deficient alkynes in dichloromethane.

  17. Operation of the annular pulsed column, (2)

    International Nuclear Information System (INIS)

    Takahashi, Keiki; Tsukada, Takeshi

    1988-01-01

    The heat of reaction generated form the uranium extraction is considered to from the temperature profile inside the pulsed column. A simulation code was developed to estimate the temperature profile, considering heat generation and counter-current heat transfer. The temperature profiles calculated using this code was found to depend on both the position of the extraction zone and the operating condition. The reported experimental result was fairly represented by this simulation code. We consider that this presented simulation code is capable of providing with the temperature profile in the pulsed column and useful for the monitoring of the uranium extraction zone. (author)

  18. Validation of NO2 and NO from the Atmospheric Chemistry Experiment (ACE

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2008-10-01

    Full Text Available Vertical profiles of NO2 and NO have been obtained from solar occultation measurements by the Atmospheric Chemistry Experiment (ACE, using an infrared Fourier Transform Spectrometer (ACE-FTS and (for NO2 an ultraviolet-visible-near-infrared spectrometer, MAESTRO (Measurement of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation. In this paper, the quality of the ACE-FTS version 2.2 NO2 and NO and the MAESTRO version 1.2 NO2 data are assessed using other solar occultation measurements (HALOE, SAGE II, SAGE III, POAM III, SCIAMACHY, stellar occultation measurements (GOMOS, limb measurements (MIPAS, OSIRIS, nadir measurements (SCIAMACHY, balloon-borne measurements (SPIRALE, SAOZ and ground-based measurements (UV-VIS, FTIR. Time differences between the comparison measurements were reduced using either a tight coincidence criterion, or where possible, chemical box models. ACE-FTS NO2 and NO and the MAESTRO NO2 are generally consistent with the correlative data. The ACE-FTS and MAESTRO NO2 volume mixing ratio (VMR profiles agree with the profiles from other satellite data sets to within about 20% between 25 and 40 km, with the exception of MIPAS ESA (for ACE-FTS and SAGE II (for ACE-FTS (sunrise and MAESTRO and suggest a negative bias between 23 and 40 km of about 10%. MAESTRO reports larger VMR values than the ACE-FTS. In comparisons with HALOE, ACE-FTS NO VMRs typically (on average agree to ±8% from 22 to 64 km and to +10% from 93 to 105 km, with maxima of 21% and 36%, respectively. Partial column comparisons for NO2 show that there is quite good agreement between the ACE instruments and the FTIRs, with a mean difference of +7.3% for ACE-FTS and +12.8% for MAESTRO.

  19. ON THE ORIGIN OF THE HIGH COLUMN DENSITY TURNOVER IN THE H I COLUMN DENSITY DISTRIBUTION

    International Nuclear Information System (INIS)

    Erkal, Denis; Gnedin, Nickolay Y.; Kravtsov, Andrey V.

    2012-01-01

    We study the high column density regime of the H I column density distribution function and argue that there are two distinct features: a turnover at N H I ≈ 10 21 cm –2 , which is present at both z = 0 and z ≈ 3, and a lack of systems above N H I ≈ 10 22 cm –2 at z = 0. Using observations of the column density distribution, we argue that the H I-H 2 transition does not cause the turnover at N H I ≈ 10 21 cm –2 but can plausibly explain the turnover at N H I ∼> 10 22 cm –2 . We compute the H I column density distribution of individual galaxies in the THINGS sample and show that the turnover column density depends only weakly on metallicity. Furthermore, we show that the column density distribution of galaxies, corrected for inclination, is insensitive to the resolution of the H I map or to averaging in radial shells. Our results indicate that the similarity of H I column density distributions at z = 3 and 0 is due to the similarity of the maximum H I surface densities of high-z and low-z disks, set presumably by universal processes that shape properties of the gaseous disks of galaxies. Using fully cosmological simulations, we explore other candidate physical mechanisms that could produce a turnover in the column density distribution. We show that while turbulence within giant molecular clouds cannot affect the damped Lyα column density distribution, stellar feedback can affect it significantly if the feedback is sufficiently effective in removing gas from the central 2-3 kpc of high-redshift galaxies. Finally, we argue that it is meaningful to compare column densities averaged over ∼ kpc scales with those estimated from quasar spectra that probe sub-pc scales due to the steep power spectrum of H I column density fluctuations observed in nearby galaxies.

  20. Global Trends of Tropospheric NO2 Observed From Space

    Science.gov (United States)

    Schneider, P.; van der A, R. J.

    2012-04-01

    Nitrogen Dioxide (NO2) is one of the major atmospheric pollutants and is primarily emitted by industrial activity and transport. While observations of NO2 are frequently being carried out at air quality stations, such measurements are not able to provide a global perspective of spatial patterns in NO2 concentrations and their associated trends due to the stations' limited spatial representativity and an extremely sparse and often completely non-existent station coverage in developing countries. Satellite observations of tropospheric NO2 are able to overcome this issue and provide an unprecedented global view of spatial patterns in NO2 levels and due to their homogeneity are well suited for studying trends. Here we present results of a global trend analysis from nearly a decade of NO2 observations made by the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CartograpHY) instrument onboard the Envisat satellite platform. Using only SCIAMACHY data allows for mapping global and regional trends at an unprecedented spatial resolution since no aggregation to the coarser resolution of other sensors is necessary. Monthly average tropospheric NO2 column data was acquired for the period between August 2002 and August 2011. A trend analysis was subsequently performed by fitting a statistical model including a seasonal cycle and linear trend to the time series extracted at each grid cell. The linear trend component and the trend uncertainty were then mapped spatially at both regional and global scales. The results show that spatially contiguous areas of significantly increasing NO2 levels are found primarily in Eastern China, with absolute trends of up to 4.05 (± 0.41) - 1015 molecules cm-2 yr-1 at the gridcell level and large areas showing rapid relative increases of 10-20 percent per year. In addition, many urban agglomerations in Asia and the Middle East similarly exhibit significantly increasing trends, with Dhaka in Bangladesh being the megacity with

  1. Mobile MAX-DOAS observation of NO2 and comparison with OMI satellite data in the western coastal areas of the Korean peninsula.

    Science.gov (United States)

    Chong, Jihyo; Kim, Young J; Gu, Myojeong; Wagner, Thomas; Song, Chul H

    2016-01-01

    Ground-based MAX-DOAS measurements have been used to retrieve column densities of atmospheric absorbers such as NO2, SO2, HCHO, and O3. In this study, mobile MAX-DOAS measurements were conducted to map the 2-D distributions of atmospheric NO2 in the western coastal areas of the Korean peninsula. A Mini-MAX-DOAS instrument was mounted on the rooftop of a mobile lab vehicle with a telescope mounted parallel to the driving direction, pointing forward. The measurements were conducted from 21 to 24 December 2010 along the western coastal areas from Gomso harbor (35.59N, 126.61E) to Gunsan harbor (35.98N, 126.67E). During mobile MAX-DOAS observations, high elevation angles were used to avoid shades from nearby obstacles. For the determination of the tropospheric vertical column density (VCD), the air mass factor (AMF) was retrieved by the so-called geometric approximation. The NO2 VCDs from 20 and 45 degree elevation angles were retrieved from mobile MAX-DOAS measurements. The tropospheric NO2 VCDs derived from mobile MAX-DOAS measurements were compared directly to those retrieved by the OMI satellite observations. Mobile MAX-DOAS VCD was in good agreement with OMI tropospheric VCD on most days. However, OMI tropospheric VCD was much higher than that of mobile MAX-DOAS on 23 December 2010. One probable reason for this difference is that OMI retrieval might overestimate NO2 VCD under haze conditions, when a pollution plume was transported over the measurement site. The mobile MAX-DOAS observations reveal much finer spatial patterns of NO2 distributions, which can provide useful information for the validation of satellite observation of atmospheric trace gases. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. A method for evaluating spatially-resolved NOx emissions using Kalman filter inversion, direct sensitivities, and space-based NO2 observations

    Directory of Open Access Journals (Sweden)

    R. V. Martin

    2008-09-01

    Full Text Available An inverse modeling method was developed and tested for identifying possible biases in emission inventories using satellite observations. The relationships between emission inputs and modeled ambient concentrations were estimated using sensitivities calculated with the decoupled direct method in three dimensions (DDM-3D implemented within the framework of the Community Multiscale Air Quality (CMAQ regional model. As a case study to test the approach, the method was applied to regional ground-level NOx emissions in the southeastern United States as constrained by observations of NO2 column densities derived from the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY satellite instrument. A controlled "pseudodata" scenario with a known solution was used to establish that the methodology can achieve the correct solution, and the approach was then applied to a summer 2004 period where the satellite data are available. The results indicate that emissions biases differ in urban and rural areas of the southeast. The method suggested slight downward (less than 10% adjustment to urban emissions, while rural region results were found to be highly sensitive to NOx processes in the upper troposphere. As such, the bias in the rural areas is likely not solely due to biases in the ground-level emissions. It was found that CMAQ was unable to predict the significant level of NO2 in the upper troposphere that was observed during the NASA Intercontinental Chemical Transport Experiment (INTEX measurement campaign. The best correlation between satellite observations and modeled NO2 column densities, as well as comparison to ground-level observations of NO2, was obtained by performing the inverse while accounting for the significant presence of NO2 in the upper troposphere not captured by the regional model.

  3. Posterior column reconstruction improves fusion rates at the level of osteotomy in three-column posterior-based osteotomies.

    Science.gov (United States)

    Lewis, Stephen J; Mohanty, Chandan; Gazendam, Aaron M; Kato, So; Keshen, Sam G; Lewis, Noah D; Magana, Sofia P; Perlmutter, David; Cape, Jennifer

    2018-03-01

    To determine the incidence of pseudarthrosis at the osteotomy site after three-column spinal osteotomies (3-COs) with posterior column reconstruction. 82 consecutive adult 3-COs (66 patients) with a minimum of 2-year follow-up were retrospectively reviewed. All cases underwent posterior 3-COs with two-rod constructs. The inferior facets of the proximal level were reduced to the superior facets of the distal level. If that was not possible, a structural piece of bone graft either from the local resection or a local rib was slotted in the posterior column defect to re-establish continual structural posterior bone across the lateral margins of the resection. No interbody cages were used at the level of the osteotomy. There were 34 thoracic osteotomies, 47 lumbar osteotomies and one sacral osteotomy with a mean follow-up of 52 (24-126) months. All cases underwent posterior column reconstructions described above and the addition of interbody support or additional posterior rods was not performed for fusion at the osteotomy level. Among them, 29 patients underwent one or more revision surgeries. There were three definite cases of pseudarthrosis at the osteotomy site (4%). Six revisions were also performed for pseudarthrosis at other levels. Restoration of the structural integrity of the posterior column in three-column posterior-based osteotomies was associated with > 95% fusion rate at the level of the osteotomy. Pseudarthrosis at other levels was the second most common reason for revision following adjacent segment disease in the long-term follow-up.

  4. OMPS/NPP PCA SO2 Total Column 1-Orbit L2 Swath 50x50km NRT

    Data.gov (United States)

    National Aeronautics and Space Administration — The OMPS-NPP L2 NM Sulfur Dioxide (SO2) Total and Tropospheric Column swath orbital collection 2 version 2.0 product contains the retrieved sulfur dioxide (SO2)...

  5. HEAT TRANSFER ANALYSIS FOR FIXED CST AND RF COLUMNS

    International Nuclear Information System (INIS)

    Lee, S

    2007-01-01

    In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, transient and steady state two-dimensional heat transfer models have been constructed for columns loaded with cesium-saturated crystalline silicotitanate (CST) or spherical Resorcinol-Formaldehyde (RF) beads and 6 molar sodium tank waste supernate. Radiolytic decay of sorbed cesium results in heat generation within the columns. The models consider conductive heat transfer only with no convective cooling and no process flow within the columns (assumed column geometry: 27.375 in ID with a 6.625 in OD center-line cooling pipe). Heat transfer at the column walls was assumed to occur by natural convection cooling with 35 C air. A number of modeling calculations were performed using this computational heat transfer approach. Minimal additional calculations were also conducted to predict temperature increases expected for salt solution processed through columns of various heights at the slowest expected operational flow rate of 5 gpm. Results for the bounding model with no process flow and no active cooling indicate that the time required to reach the boiling point of ∼130 C for a CST-salt solution mixture containing 257 Ci/liter of Cs-137 heat source (maximum expected loading for SCIX applications) at 35 C initial temperature is about 6 days. Modeling results for a column actively cooled with external wall jackets and the internal coolant pipe (inlet coolant water temperature: 25 C) indicate that the CST column can be maintained non-boiling under these conditions indefinitely. The results also show that the maximum temperature of an RF-salt solution column containing 133 Ci/liter of Cs-137 (maximum expected loading) will never reach boiling under any conditions (maximum predicted temperature without cooling: 88 C). The results indicate that a 6-in cooling pipe at the center of the column provides the most effective cooling mechanism for reducing the maximum

  6. NO2 DOAS measurements from ground and space: comparison of ground based measurements and OMI data in Mexico City

    Science.gov (United States)

    Rivera, C.; Stremme, W.; Grutter, M.

    2012-04-01

    The combination of satellite data and ground based measurements can provide valuable information about atmospheric chemistry and air quality. In this work we present a comparison between measured ground based NO2 differential columns at the Universidad Nacional Autónoma de México (UNAM) in Mexico City, using the Differential Optical Absorption Spectroscopy (DOAS) technique and NO2 total columns measured by the Ozone Monitoring Instrument (OMI) onboard the Aura satellite using the same measurement technique. From these data, distribution maps of average NO2 above the Mexico basin were constructed and hot spots inside the city could be identified. In addition, a clear footprint was detected from the Tula industrial area, ~50 km northwest of Mexico City, where a refinery, a power plant and other industries are located. A less defined footprint was identified in the Cuernavaca basin, South of Mexico City, and the nearby cities of Toluca and Puebla do not present strong enhancements in the NO2 total columns. With this study we expect to cross-validate space and ground measurements and provide useful information for future studies.

  7. Energy Efficient Operation of Distillation Columns and a Reactor Applying Irreversible Thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Koeijer, Gelein M. de

    2002-05-01

    In this thesis the entropy production rates of diabatic distillation columns and a SO{sub 2} converter were minimised. This is the same as maximising the second law energy efficiency of the systems. The development of chemical industry can be made more sustainable by knowing this minimum. We found that the entropy production rate of distillation could be reduced up to 50 %. In order to achieve this reduction, heat exchangers were added on each tray. The characteristics of an optimum distillation column were presented. Furthermore, the entropy production rate of a SO{sub 2} converter was reduced with 16.7 % by altering the heights of catalytic beds, transfer areas of heat exchangers, and temperature differences over heat exchangers. These reductions show that there is still a large improvement potential in chemical industry. By applying the improved operations the world oil production can be reduced in the order of magnitude of 1 %. A similar reduction in the emission of the greenhouse gas CO{sub 2} can be expected. For deriving the entropy production rate in a systematic manner the theory of irreversible thermodynamics was useful. A simpler and a more complicated equation for the entropy production rate of distillation were derived. The simpler equation used only one force-flux product. It was suitable for minimisation of the entropy production rate of columns with the assumption of equilibrium between the outlets on each tray. The more complicated equation was able to describe satisfactorily the entropy production rate of an experimental column that separated the non-ideal mixture water-ethanol. It was next used to derive an extended set of transport equations for distillation, that includes the interface and the Soret effect (or thermal diffusion). Finally, irreversible thermodynamics was used to describe the contribution to the entropy production rate of heat transfer in heat exchangers. This contribution had a significant impact on the results of the

  8. Plutonium-239 sorption and transport on/in unsaturated sediments. Comparison of batch and column experiments for determining sorption coefficients

    International Nuclear Information System (INIS)

    Jinchuan Xie; Jiachun Lu; Xiaohua Zhou; Xuhui Wang; Mei Li; Lili Du; Yueheng Liu; Guoqing Zhou

    2013-01-01

    Sorption (distribution) coefficients of plutonium were most often derived by static batch experiments. However, it is not clear how unsaturated flow conditions including moisture content and pore water velocity change the sorption coefficients. Transport experiments of plutonium through the unsaturated sediments packed into the columns were then performed in order to determine the sorption coefficients (column-K ds ). Static batch experiments were also conducted to obtain batch-K ds and then compare the differences between batch-K ds and column-K ds . The results show that unsaturated flow conditions had no significant effect on column-K ds , and the average column-K d value was 1.74 ± 0.02 m 3 /kg. By comparison, batch-K d values spanned several orders of magnitude, regardless of the specified liquid-solid conditions. Moreover, the batch-K d (22.7 m 3 /kg) at the standard L/S (4 mL/g) recommended by ASTM D 4319 was over an order of magnitude larger than the average column-K d . (author)

  9. Rectification of catalyst separation column at HWP, Thal (Paper No. 5.7)

    International Nuclear Information System (INIS)

    Prakash, R.; Bhaskaran, M.

    1992-01-01

    Heavy Water Plant, Thal is based on the monothermal ammonia hydrogen process. Liquid ammonia containing potassium amide catalyst is contacted with the synthesis gas where-in deuterium from hydrogen gets transferred to liquid phase. There are two parallel streams A and B with a common ammonia synthesis unit. The system is provided with an ammonia cracker and ammonia synthesis for providing the reflux gas and liquid for the enrichment process. The parameters such as steam valve opening, column pressure, reflux, condensate valve opening, cooling water valve position, cracking load of the unit before and after the rectification, etc. are discussed. (author). 2 tabs., 2 figs

  10. The AOTF-Based NO2 Camera

    Science.gov (United States)

    Dekemper, E.; Fussen, D.; Vanhellemont, F.; Vanhamel, J.; Pieroux, D.; Berkenbosch, S.

    2017-12-01

    In an urban environment, nitrogen dioxide is emitted by a multitude of static and moving point sources (cars, industry, power plants, heating systems,…). Air quality models generally rely on a limited number of monitoring stations which do not capture the whole pattern, neither allow for full validation. So far, there has been a lack of instrument capable of measuring NO2 fields with the necessary spatio-temporal resolution above major point sources (power plants), or more extended ones (cities). We have developed a new type of passive remote sensing instrument aiming at the measurement of 2-D distributions of NO2 slant column densities (SCDs) with a high spatial (meters) and temporal (minutes) resolution. The measurement principle has some similarities with the popular filter-based SO2 camera (used in volcanic and industrial sulfur emissions monitoring) as it relies on spectral images taken at wavelengths where the molecule absorption cross section is different. But contrary to the SO2 camera, the spectral selection is performed by an acousto-optical tunable filter (AOTF) capable of resolving the target molecule's spectral features. A first prototype was successfully tested with the plume of a coal-firing power plant in Romania, revealing the dynamics of the formation of NO2 in the early plume. A lighter version of the NO2 camera is now being tested on other targets, such as oil refineries and urban air masses.

  11. Retention of nitrous gases in scrubber columns

    International Nuclear Information System (INIS)

    Nakazone, A.K.; Costa, R.C.; Lobao, A.S.T.; Matsuda, H.T.; Araujo, B.F. de

    1988-01-01

    During the UO 2 dissolution in nitric acid, some different species of NO (sub)x are released. The off gas can either be refluxed to the dissolver or be released and retained on special colums. The final composition of the solution is the main parameter to take in account. A process for nitrous gases retention using scrubber colums containing H 2 O or diluted HNO 3 is presented. Chemiluminescence measurement was employed to NO x evaluation before and after scrubing. Gas flow, temperature, residence time are the main parameters considered in this paper. For the dissolution of 100g UO 2 in 8M nitric acid, a 6NL/h O 2 flow was the best condition for the NO/NO 2 oxidation with maximum absorption in the scrubber columns. (author) [pt

  12. Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for Column CO2 Measurements

    Science.gov (United States)

    Campbell, J. F.; Lin, B.; Obland, M. D.; Liu, Z.; Kooi, S. A.; Fan, T. F.; Nehrir, A. R.; Meadows, B.; Browell, E. V.

    2016-12-01

    Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for Column CO2 MeasurementsJoel F. Campbell1, Bing Lin1, Michael D. Obland1, Zhaoyan Liu1, Susan Kooi2, Tai-Fang Fan2, Amin R. Nehrir1, Byron Meadows1, Edward V. Browell31NASA Langley Research Center, Hampton, VA 23681 2SSAI, NASA Langley Research Center, Hampton, VA 23681 3STARSS-II Affiliate, NASA Langley Research Center, Hampton, VA 23681 AbstractGlobal and regional atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission and the Atmospheric Carbon and Transport (ACT) - America project are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity-Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space and airborne platforms to meet the ASCENDS and ACT-America science measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud returns. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby minimizing bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new sub-meter hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. These techniques are used in a new data processing

  13. Performance evaluation of a rectifier column using gamma column scanning

    Directory of Open Access Journals (Sweden)

    Aquino Denis D.

    2017-12-01

    Full Text Available Rectifier columns are considered to be a critical component in petroleum refineries and petrochemical processing installations as they are able to affect the overall performance of these facilities. It is deemed necessary to monitor the operational conditions of such vessels to optimize processes and prevent anomalies which could pose undesired consequences on product quality that might lead to huge financial losses. A rectifier column was subjected to gamma scanning using a 10-mCi Co-60 source and a 2-inch-long detector in tandem. Several scans were performed to gather information on the operating conditions of the column under different sets of operating parameters. The scan profiles revealed unexpected decreases in the radiation intensity at vapour levels between trays 2 and 3, and between trays 4 and 5. Flooding also occurred during several scans which could be attributed to parametric settings.

  14. The prediction of concentration profiles for a NIMCIX column absorbing uranium from aqueous solution

    International Nuclear Information System (INIS)

    Wright, R.S.

    1979-01-01

    A procedure is proposed for the prediction of concentration profiles for a countercurrent ion-exchange absorption column, use being made of equilibrium and kinetic data derived from small-scale batch tests. A comparison is presented between the predictions and the measured performance of a column (2,5 m in diameter) absorbing uranium from solution. The method is shown to be adequate for design purposes provided that the data used are from tests in which the solution and resin conditions approximate those for which the plant is being designed [af

  15. How organic carbon derived from multiple sources contributes to carbon sequestration processes in a shallow coastal system?

    Science.gov (United States)

    Watanabe, Kenta; Kuwae, Tomohiro

    2015-04-16

    Carbon captured by marine organisms helps sequester atmospheric CO 2 , especially in shallow coastal ecosystems, where rates of primary production and burial of organic carbon (OC) from multiple sources are high. However, linkages between the dynamics of OC derived from multiple sources and carbon sequestration are poorly understood. We investigated the origin (terrestrial, phytobenthos derived, and phytoplankton derived) of particulate OC (POC) and dissolved OC (DOC) in the water column and sedimentary OC using elemental, isotopic, and optical signatures in Furen Lagoon, Japan. Based on these data analysis, we explored how OC from multiple sources contributes to sequestration via storage in sediments, water column sequestration, and air-sea CO 2 exchanges, and analyzed how the contributions vary with salinity in a shallow seagrass meadow as well. The relative contribution of terrestrial POC in the water column decreased with increasing salinity, whereas autochthonous POC increased in the salinity range 10-30. Phytoplankton-derived POC dominated the water column POC (65-95%) within this salinity range; however, it was minor in the sediments (3-29%). In contrast, terrestrial and phytobenthos-derived POC were relatively minor contributors in the water column but were major contributors in the sediments (49-78% and 19-36%, respectively), indicating that terrestrial and phytobenthos-derived POC were selectively stored in the sediments. Autochthonous DOC, part of which can contribute to long-term carbon sequestration in the water column, accounted for >25% of the total water column DOC pool in the salinity range 15-30. Autochthonous OC production decreased the concentration of dissolved inorganic carbon in the water column and thereby contributed to atmospheric CO 2 uptake, except in the low-salinity zone. Our results indicate that shallow coastal ecosystems function not only as transition zones between land and ocean but also as carbon sequestration filters. They

  16. Relationship between chlorophyll-a and column primary production

    Digital Repository Service at National Institute of Oceanography (India)

    Dalal, S.G.; Bhargava, R.M.S.

    Relationship between surface chlorophyll a and column primary production has been established to help in estimating the latter more quickly and accurately. The equation derived is Primary Production, y = 0.54 Ln Chl a - 0.6. The relationship...

  17. Simultaneous determination of 1- and 2-naphthol in human urine using on-line clean-up column-switching liquid chromatography-fluorescence detection.

    Science.gov (United States)

    Preuss, Ralf; Angerer, Jürgen

    2004-03-05

    We developed a new 3-D HPLC method for on-line clean-up and simultaneous quantification of two important naphthalene metabolites, 1-naphthol and 2-naphthol, in human urine. Except an enzymatic hydrolysis no further sample pre-treatment is necessary. The metabolites are stripped from urinary matrix by on-line extraction on a restricted access material pre-column (RAM RP-8), transferred in backflush mode onto a silica-based CN-(cyano)phase column for further purification from interfering substances. By another successive column switching step both analytes are transferred with a minimum of overlapping interferences onto a C12 bonded reversed phase column with trimethylsilyl endcapping where the final separation is carried out. The entire arrangement is software controlled. Eluting analytes are quantified by fluorescence detection (227/430 nm) after an external calibration. Within a total run time of 40 min we can selectively quantify both naphthols with detection limits in the lower ppb range (1.5 and 0.5 microg/l for 1- and 2-naphthol, respectively) with excellent reliability (ensured by precision, accuracy, matrix-independency and FIOH quality assurance program participation). First results on a collective of 53 occupationally non exposed subjects showed mean levels of 11.0 microg/l (1-naphthol) and 12.9 microg/l (2-naphthol). Among smokers (n=21) a significantly elevated mean level of urinary naphthols was determined (1-naphthol: 19.2 microg/l and 2-naphthol: 23.7 microg/l) in comparison to non smokers (n=32; 1-naphthol: 5.6 microg/l, 2-naphthol: 5.6 microg/l).

  18. Effect of volcanic aerosol on stratospheric NO2 and N2O5 from 2002–2014 as measured by Odin-OSIRIS and Envisat-MIPAS

    Directory of Open Access Journals (Sweden)

    C. Adams

    2017-07-01

    Full Text Available Following the large volcanic eruptions of Pinatubo in 1991 and El Chichón in 1982, decreases in stratospheric NO2 associated with enhanced aerosol were observed. The Optical Spectrograph and Infrared Imaging Spectrometer (OSIRIS measured the widespread enhancements of stratospheric aerosol following seven volcanic eruptions between 2002 and 2014, although the magnitudes of these eruptions were all much smaller than the Pinatubo and El Chichón eruptions. In order to isolate and quantify the relationship between volcanic aerosol and NO2, NO2 anomalies were calculated using measurements from OSIRIS and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS. In the tropics, variability due to the quasi-biennial oscillation was subtracted from the time series. OSIRIS profile measurements indicate that the strongest anticorrelations between NO2 and volcanic aerosol extinction were for the 5 km layer starting  ∼  3 km above the climatological mean tropopause at the given latitude. OSIRIS stratospheric NO2 partial columns in this layer were found to be smaller than background NO2 levels during these aerosol enhancements by up to  ∼  60 % with typical Pearson correlation coefficients of R ∼ −0. 7. MIPAS also observed decreases in NO2 partial columns during periods affected by volcanic aerosol, with percent differences of up to  ∼  25 % relative to background levels. An even stronger anticorrelation was observed between OSIRIS aerosol optical depth and MIPAS N2O5 partial columns, with R ∼ −0. 9, although no link with MIPAS HNO3 was observed. The variation in OSIRIS NO2 with increasing aerosol was found to be consistent with simulations from a photochemical box model within the estimated model uncertainty.

  19. Miniaturized Laser Heterodyne Radiometer for Measurements of CO2 in the Atmospheric Column

    Science.gov (United States)

    Wilson, E. L.; Mclinden, M. L.; Miller, J. H.; Allan, G. R.; Lott, L. E.; Melroy, H. R.; Clarke, G. B.

    2013-01-01

    We have developed a low-cost, miniaturized laser heterodyne radiometer for highly sensitive measurements of carbon dioxide (CO2) in the atmospheric column. In this passive design, sunlight that has undergone absorption by CO2 in the atmosphere is collected and mixed with continuous wave laser light that is step-scanned across the absorption feature centered at 1,573.6 nm. The resulting radio frequency beat signal is collected as a function of laser wavelength, from which the total column mole fraction can be de-convolved. We are expanding this technique to include methane (CH4) and carbon monoxide (CO), and with minor modifications, this technique can be expanded to include species such as water vapor (H2O) and nitrous oxide (N2O).

  20. Glyoxal Vertical Column Retrievals from the GOME-2/METOP-A European Spaceborne Sensor and Comparisons with the IMAGESv2 CT Model

    Science.gov (United States)

    Lerot, C.; Stavrakou, T.; de Smedt, I.; Muller, J. J.; van Roozendael, M.

    2010-12-01

    Glyoxal is mostly formed in our atmosphere as an intermediate product in the oxidation of non-methane volatile organic compounds (NMVOC). To a lesser extent, it is also directly emitted from biomass burning events and from fossil- and bio-fuel combustion processes. Several studies have estimated its atmospheric lifetime to 2-3 hours, which makes of glyoxal a good indicator for short-lived NMVOC emissions. Glyoxal is also known to be a precursor for secondary organic aerosols and could help to reduce the gap between observations and models for organic aerosol abundances. The three absorption bands of glyoxal in the visible region allow applying the DOAS (Differential Optical Absorption Spectroscopy) technique to retrieve its vertical column densities from the nadir backscattered light measurements performed by the GOME-2 satellite sensor. This instrument has been launched in October 2006 on board of the METOP-A platform and is characterized by a spatial resolution of 80 km x 40 km and by a large scan-width (1920 km) leading to a global coverage reached in 1.5 day. The GOME-2 glyoxal retrieval algorithm developed at BIRA-IASB accounts for the liquid water absorption and provides geophysically sound column measurements not only over lands but also over oceanic regions where spectral interferences between glyoxal and liquid water have been shown to be significant. The a-priori glyoxal vertical distribution required for the slant to vertical column conversion is provided by the global chemical transport model IMAGESv2. The highest glyoxal vertical column densities are mainly observed in continental tropical regions, while the mid-latitude columns strongly depend on the season with maximum values during warm months. An anthropogenic signature is also observed in highly populated regions of Asia. Comparisons with glyoxal columns simulated with IMAGESv2 in different regions of the world generally point to a missing glyoxal source in current models. As already reported from

  1. Vertical Distribution of NO, NO(2), and HNO(3) as Derived from Stratospheric Absorption Infrared Spectra.

    Science.gov (United States)

    Fontanella, J C; Girard, A; Gramont, L; Louisnard, N

    1975-04-01

    This paper is devoted to the results concerning NO, NO(2), and HNO(3) obtained during airborne experiments performed in June-July 1973 on Concorde 001. The altitude of flight was about 16 km. Results concerning NO are, within the accuracy of measurement, in agreement with results of a previousspectrometric balloonborne experiment conducted jointly by IASB and ONERA (14 May 1973). Nitric oxide is concentrated in stratospheric layers clearly above the flight altitude. Integrated amount of NO along the optical path is (4 +/- 1.5) x 10(16) mol cm(-2) for a solar elevation varying from +2 degrees above the horizontal plane to -1 degrees . A value of 6 x 10(8) mol cm(-3) may be given as an upper limit for the local concentration at the flight altitude. Thereis no significant difference in the integrated amount observed at sunset and sunrise. Measured value of NO(2) local concentration at 15.5 km is (1.1 +/- 0.2) x 10(9) mol cm(-3), in sunset conditions. This value is not greatly modified between 15 km and 30 km. Measured value of HNO(3). This value increases with altitude between 15 km and 20 km. The local concentration is maximum at 20 km. The measured value is (2 +/- 1) x 10(10) mol cm(-3) at 20 km. It seems that local concentration decreases rapidly above 20 km.

  2. Modeling Separation Dynamics in a Multi-Tray Bio-Ethanol Distillation Column

    DEFF Research Database (Denmark)

    Løhndorf, Petar Durdevic; Pedersen, Simon; Yang, Zhenyu

    2015-01-01

    the product quality and energy consumption in a typical bio-ethanol distillation column is proposed in this paper. The proposed model is derived based on mass and energy balance principles, with an empirical model of the evaporation dynamics of liquids on column trays. The model parameters are identified......The high energy consumption of popularly used distillation columns has motivated development of energytracking dynamic models with the ultimate objective for potential better energy and quality control of these separation facilities. A dynamic model being able to explicitly describe both...

  3. An overall theory of separation on column or on square cascade

    International Nuclear Information System (INIS)

    Hodor, I.

    1984-01-01

    An overall theory of column or square cascade separation has been developed on the basis of only a few assumptions, irrespective of the particular structure of the separating element or the involved physical-chemical processes. The main advantage of the theory is that it clarifies and facilitates the derivation of the mass transfer parameters. Using examples, it is demonstrated that well-known theories, e.g. that of the thermal diffusion column, can be reproduced. The theory is also applied to spray columns whose theory has so far been only slightly developed. (author)

  4. Plasma column development in the CO2 laser-heated solenoid

    International Nuclear Information System (INIS)

    Tighe, W.; Offenberger, A.A.; Capjack, C.E.

    1987-01-01

    Axial and radial plasma dynamics in the CO 2 laser-heated solenoid have been studied experimentally and numerically. The axial behavior is found to be well described by a self-regulated bleaching wave model. The radial expansion is found to be strongly dependent on the focusing ratio of the input laser beam. With a fast focus ( f/5), the early radial expansion rate is twice that found with a slower focusing arrangement ( f/15). The faster focusing ratio also results in a significantly wider plasma column. On the other hand, no significant dependence of f/number on the axial propagation was found. A finite ionization time and the rapid formation of a density minimum on axis are observed and verify earlier experimental results. Detailed comparisons are made with a 2-D magnetohydrodynamic (MHD) and laser propagation code. The axial and radial plasma behavior and, in particular, the dependence of the radial behavior on the focal ratio of the laser are reasonably well supported by the simulation results. Computational results are also in good agreement with experimental measurements of temperature and density using stimulated scattering (Brillouin, Raman) and interferometry diagnostic techniques

  5. Improved Focusing Method for 3-D Imaging using Row–Column-Addressed 2-D Arrays

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Engholm, Mathias; Stuart, Matthias Bo

    2017-01-01

    A row–column-addressed (RCA) 2-D array can be interpreted as two orthogonal 1-D arrays. By transmitting with row elements and receiving the echoes through column elements or vice versa, a rectilinear volume in front of the array can be beamformed. Since the transmit and receive 1-D arrays are ort...... measurements with a PZT λ/2-pitch 3 MHz 62+62 RCA 2-D transducer probe. A synthetic aperture imaging sequence with single element transmissions at a time, is designed for imaging down to 14 cm at a volume rate of 44 Hz....

  6. [Detection of monoamine neurotransmitters and its metabolites by high performance liquid chromatograph after pre-column derivatization of dansyl chloride column].

    Science.gov (United States)

    Huang, Xiao; Chen, Jia-wen; He, Li-ping; Kang, Xue-jun

    2012-12-01

    To develop a high performance liquid chromatography (HPLC) for detection of monoamine neurotransmitters and its metabolites after pre-column derivatization with dansyl chloride. The C(18) chromatograph column (150 mm×4.6 mm×5 µm) was selected for detection, and derived by dansyl chloride (10 mg/ml) under the condition of 50°C water bath by pH11 buffer solution. 20 µl acetic acid acetone solution (1.0 mol/L) was then mixed in for termination of the reaction. Then the solution was cooling to room temperature, 0.1 mol/L acetic acid zinc-acetonitrile-tetrahydrofuran solution was adopted for mobile phrase, with the volume ratio at 62:35:3. The flow rate was 1.0 ml/min between 0-10 min, 2.0 ml/min between 10-35 min. The ultraviolet detection wavelength was 286 nm. The above method separately detected monoamine neurotransmitters and its metabolites and evaluated the limit of detection, accurate degree and accuracy degree. The linear relations between each component was good in the range of 1 - 20 µg/ml (r = 0.999). The lowest detection limit of norepinephrine, dopamine, 5-hydroxytryptamine and the metabolites 3-methoxy-4-benzoglycols, homovanillic acid and 5-heteroauxin were separately 0.60, 0.80, 0.41, 0.21, 0.19 and 0.1 µg/ml; while the average recovery rates were between 78.5% - 95.9%, and the relative standard deviation (RSD) was 6.62%, 7.64%, 2.98%, 3.60%, 5.09% and 3.09%, respectively. In the process of selection and optimization of the chromatographic conditions, we observed the importance of metal ions to discretion, and discussed the temperature, pH of the buffer solution and dosage of dansyl chloride in derivation. Under the above conditions, the reaction was perfect, and the baseline of the detected materials thoroughly separated. The method to detect monoamine neurotransmitters and its metabolites by HPLC and pre-column derivatization with dansyl chloride was established; and this method could provide reference for the detection of polyamine by HPLC.

  7. Investigating the Effect of Column Geometry on Separation Efficiency using 3D Printed Liquid Chromatographic Columns Containing Polymer Monolithic Phases.

    Science.gov (United States)

    Gupta, Vipul; Beirne, Stephen; Nesterenko, Pavel N; Paull, Brett

    2018-01-16

    Effect of column geometry on the liquid chromatographic separations using 3D printed liquid chromatographic columns with in-column polymerized monoliths has been studied. Three different liquid chromatographic columns were designed and 3D printed in titanium as 2D serpentine, 3D spiral, and 3D serpentine columns, of equal length and i.d. Successful in-column thermal polymerization of mechanically stable poly(BuMA-co-EDMA) monoliths was achieved within each design without any significant structural differences between phases. Van Deemter plots indicated higher efficiencies for the 3D serpentine chromatographic columns with higher aspect ratio turns at higher linear velocities and smaller analysis times as compared to their counterpart columns with lower aspect ratio turns. Computational fluid dynamic simulations of a basic monolithic structure indicated 44%, 90%, 100%, and 118% higher flow through narrow channels in the curved monolithic configuration as compared to the straight monolithic configuration at linear velocities of 1, 2.5, 5, and 10 mm s -1 , respectively. Isocratic RPLC separations with the 3D serpentine column resulted in an average 23% and 245% (8 solutes) increase in the number of theoretical plates as compared to the 3D spiral and 2D serpentine columns, respectively. Gradient RPLC separations with the 3D serpentine column resulted in an average 15% and 82% (8 solutes) increase in the peak capacity as compared to the 3D spiral and 2D serpentine columns, respectively. Use of the 3D serpentine column at a higher flow rate, as compared to the 3D spiral column, provided a 58% reduction in the analysis time and 74% increase in the peak capacity for the isocratic separations of the small molecules and the gradient separations of proteins, respectively.

  8. Admittance Scanning for Whole Column Detection.

    Science.gov (United States)

    Stamos, Brian N; Dasgupta, Purnendu K; Ohira, Shin-Ichi

    2017-07-05

    Whole column detection (WCD) is as old as chromatography itself. WCD requires an ability to interrogate column contents from the outside. Other than the obvious case of optical detection through a transparent column, admittance (often termed contactless conductance) measurements can also sense changes in the column contents (especially ionic content) from the outside without galvanic contact with the solution. We propose here electromechanically scanned admittance imaging and apply this to open tubular (OT) chromatography. The detector scans across the column; the length resolution depends on the scanning velocity and the data acquisition frequency, ultimately limited by the physical step resolution (40 μm in the present setup). Precision equal to this step resolution was observed for locating an interface between two immiscible liquids inside a 21 μm capillary. Mechanically, the maximum scanning speed was 100 mm/s, but at 1 kHz sampling rate and a time constant of 25 ms, the highest practical scan speed (no peak distortion) was 28 mm/s. At scanning speeds of 0, 4, and 28 mm/s, the S/N for 180 pL (zone length of 1.9 mm in a 11 μm i.d. column) of 500 μM KCl injected into water was 6450, 3850, and 1500, respectively. To facilitate constant and reproducible contact with the column regardless of minor variations in outer diameter, a double quadrupole electrode system was developed. Columns of significant length (>1 m) can be readily scanned. We demonstrate its applicability with both OT and commercial packed columns and explore uniformity of retention along a column, increasing S/N by stopped-flow repeat scans, etc. as unique applications.

  9. Plant-wide control of coupled distillation columns with partial condensers

    International Nuclear Information System (INIS)

    Ebrahimzadeh, Edris; Baxter, Larry L.

    2016-01-01

    Highlights: • Extractive distillation system for CO_2–ethane azeotrope separation. • Control of distillation column systems that have interconnected partial condenser and total condenser columns. • Single-end temperature control of distillation columns. • Aspen Dynamics tools applied for rigorous steady-state and dynamic simulations. - Abstract: Conventional distillation control processes use vapor distillate flowrate to control column pressure and condenser heat removal to control the reflux drum level. These intuitive control systems work well for isolated columns or columns with total condensers. However, these controls are not effective when columns with partial condensers occur in series. The pressure and reflux drum level interact in such systems in ways that defeat conventional control systems, rendering them unable to maintain product purities in the presence of large feed flowrate and composition disturbances. This investigation documents a plant-wide control structure that can address this issue by controlling pressure through reflux heat removal rate and reflux drum level by reflux flow rate. This control system demonstrates its capability to handle large disturbances in throughput and feed composition through a series of Aspen simulations. This alternative system is no more complicated than the conventional system and should work on distillation columns of nearly all designs, not just the coupled partial condenser designs for which it is essential. Common natural gas processing provides a specific example of this alternative control system. Natural gas commonly includes high concentrations of CO_2 that must be removed prior to pipeline or LNG distribution. The existence of a minimum-boiling temperature azeotrope between ethane, virtually always present in natural gas, and carbon dioxide complicates the separation of CO_2 from the hydrocarbons. This separation commonly employs extractive distillation with high-molecular-weight hydrocarbons. Our

  10. Modeling Stone Columns.

    Science.gov (United States)

    Castro, Jorge

    2017-07-11

    This paper reviews the main modeling techniques for stone columns, both ordinary stone columns and geosynthetic-encased stone columns. The paper tries to encompass the more recent advances and recommendations in the topic. Regarding the geometrical model, the main options are the "unit cell", longitudinal gravel trenches in plane strain conditions, cylindrical rings of gravel in axial symmetry conditions, equivalent homogeneous soil with improved properties and three-dimensional models, either a full three-dimensional model or just a three-dimensional row or slice of columns. Some guidelines for obtaining these simplified geometrical models are provided and the particular case of groups of columns under footings is also analyzed. For the latter case, there is a column critical length that is around twice the footing width for non-encased columns in a homogeneous soft soil. In the literature, the column critical length is sometimes given as a function of the column length, which leads to some disparities in its value. Here it is shown that the column critical length mainly depends on the footing dimensions. Some other features related with column modeling are also briefly presented, such as the influence of column installation. Finally, some guidance and recommendations are provided on parameter selection for the study of stone columns.

  11. Thermodynamic properties of nonstoichiometric H-Nb2 Osub(5-x) derived from a statistical model of its defect structure

    International Nuclear Information System (INIS)

    Schilling, O.F.

    1986-01-01

    A statistical method for the treatment of the defect structure of oxides is applied to H-Nb 2 Osub(5-x) and its thermodynamic properties are derived as a function of x and temperature. The results based on a model of Nb O 3 vacancy clusters located at the tetrahedral columns of the structure presented very good agreement with experimental data in the literature [2]. Further, the predicted arrangement of the clusters of vacancies along the columns at the limiting composition of the H-Nb 2 O 5 phase indicates, according to recent electron microscopy experiments [18, 19], that the initial step of the transformation is the collapse of the structure around rows of defective sites along the columns, involving Andersson and Wadsley's [20] cooperative migration of atoms. The limiting compositions of the H-Nb 2 O 5 and Nb 53 O 132 phases are also correctly predicted on the basis of electrostatic interactions among defect units only. Thus elastic interactions among planar defects appear to affect only the arrangement of such defects, and not the compositions of the initial and final compounds. (author)

  12. Theoretical study on separation of H2/HD by multi-column interlinking cryogenic distillation

    International Nuclear Information System (INIS)

    Xia Xiulong

    2010-01-01

    Multi-column interlinking is an effective separation method adopted for enrichment of trace deuterium and tritium. Conceptual design and proper operating mode were proposed for separation of H2/HD by cryogenic distillation with three interlinking columns,and separation performance were obtained.Enrichment of 20 x 10 x 10 achieved with proper operating mode indicating multi-column interlinking is specially suitable for trace composition enrichment. Pressure and reflux ratio' effect on separation performance were also investigated. As pressure increased from 0.6 atm to 1.5 atm, deuterium stripping efficiency dropped from 99.79% to 99.44%; As reflux ratio increased from 3 to 5, deuterium stripping efficiency increased from 99.67% to 99.81%. (authors)

  13. Local buckling of composite channel columns

    Science.gov (United States)

    Szymczak, Czesław; Kujawa, Marcin

    2018-05-01

    The investigation concerns local buckling of compressed flanges of axially compressed composite channel columns. Cooperation of the member flange and web is taken into account here. The buckling mode of the member flange is defined by rotation angle a flange about the line of its connection with the web. The channel column under investigation is made of unidirectional fibre-reinforced laminate. Two approaches to member orthotropic material modelling are performed: the homogenization with the aid of theory of mixture and periodicity cell or homogenization upon the Voigt-Reuss hypothesis. The fundamental differential equation of local buckling is derived with the aid of the stationary total potential energy principle. The critical buckling stress corresponding to a number of buckling half-waves is assumed to be a minimum eigenvalue of the equation. Some numerical examples dealing with columns are given here. The analytical results are compared with the finite element stability analysis carried out by means of ABAQUS software. The paper is focused on a close analytical solution of the critical buckling stress and the associated buckling mode while the web-flange cooperation is assumed.

  14. The MOVPE growth mechanism of catalyst-free self-organized GaN columns in H2 and N2 carrier gases

    Science.gov (United States)

    Wang, Xue; Jahn, Uwe; Ledig, Johannes; Wehmann, Hergo-H.; Mandl, Martin; Straßburg, Martin; Waag, Andreas

    2013-12-01

    Columnar structures of III-V semiconductors recently attract considerable attention because of their potential applications in novel optoelectronic and electronic devices. In the present study, the mechanisms for the growth of catalyst-free self-organized GaN columns on sapphire substrate by metal organic vapor phase epitaxy have been thoroughly investigated. The growth behaviours are strongly affected by the choice of carrier gas. If pure nitrogen is used, Ga droplets are able to accumulate on the top of columns during growth, and they are converted into a high quality GaN layer during the cool down phase due to nitridation. Hydrogen as the carrier gas can improve the optical quality of the overall GaN columns substantially, and in addition increase the vertical growth rate. In this case, no indication of Ga droplets could be detected. Furthermore, silane doping during the growth promotes the vertical growth in both cases either pure nitrogen or pure hydrogen as the carrier gas.

  15. Validity of using modified capillary column with larger diameter to study the Cs diffusion in local Taiwan laterite

    International Nuclear Information System (INIS)

    Tsing-Hai Wang; National Tsing Hua University, Hsinchu, Taiwan; Wen-Chun Yeh; Shih-Chin Tsai; Yi-Lin Jan; Shi-Ping Teng

    2008-01-01

    We have examined the working diameter of capillary columns with diameter of 5, 7, 10 and 20 mm. These modified capillary columns were carefully filled with local Taiwan laterite (LTL). The porosity and density of these packed columns was 0.51±0.02 g/g and 1.27±0.05 g/cm 3 , respectively. The diffusion experiments were then carried out in synthetic groundwater with Cs loading of 0.1mM at room temperature. Experimental results have shown that the diffusion profiles of modified capillary columns fit Fick's second law very well. This result revealed that the working diameter of a capillary column can be expanded to at least to 20 mm without affecting the validity of the derived diffusion coefficients. Among these columns, the ones with 5 mm diameter show the most consistent results of the derived K d , apparent and effective diffusion coefficients. Although the derived distribution and effective diffusion coefficients slightly decrease as the diameter of these columns increases due to the increase of the solid/liquid ratio. These values are still informative of the Cs diffusion in local Taiwan laterite. Moreover, our results clearly demonstrate the potential of using 'modified capillary method' to study the diffusion behaviors of concerned radionuclide because columns with large diameter enable the filling with more versatile geological substances. (author)

  16. Space-based retrieval of NO2 over biomass burning regions: quantifying and reducing uncertainties

    Science.gov (United States)

    Bousserez, N.

    2014-10-01

    The accuracy of space-based nitrogen dioxide (NO2) retrievals from solar backscatter radiances critically depends on a priori knowledge of the vertical profiles of NO2 and aerosol optical properties. This information is used to calculate an air mass factor (AMF), which accounts for atmospheric scattering and is used to convert the measured line-of-sight "slant" columns into vertical columns. In this study we investigate the impact of biomass burning emissions on the AMF in order to quantify NO2 retrieval errors in the Ozone Monitoring Instrument (OMI) products over these sources. Sensitivity analyses are conducted using the Linearized Discrete Ordinate Radiative Transfer (LIDORT) model. The NO2 and aerosol profiles are obtained from a 3-D chemistry-transport model (GEOS-Chem), which uses the Fire Locating and Monitoring of Burning Emissions (FLAMBE) daily biomass burning emission inventory. Aircraft in situ data collected during two field campaigns, the Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) and the Dust and Biomass-burning Experiment (DABEX), are used to evaluate the modeled aerosol optical properties and NO2 profiles over Canadian boreal fires and West African savanna fires, respectively. Over both domains, the effect of biomass burning emissions on the AMF through the modified NO2 shape factor can be as high as -60%. A sensitivity analysis also revealed that the effect of aerosol and shape factor perturbations on the AMF is very sensitive to surface reflectance and clouds. As an illustration, the aerosol correction can range from -20 to +100% for different surface reflectances, while the shape factor correction varies from -70 to -20%. Although previous studies have shown that in clear-sky conditions the effect of aerosols on the AMF was in part implicitly accounted for by the modified cloud parameters, here it is suggested that when clouds are present above a surface layer of scattering aerosols, an explicit

  17. High-resolution 2-deoxyglucose mapping of functional cortical columns in mouse barrel cortex.

    Science.gov (United States)

    McCasland, J S; Woolsey, T A

    1988-12-22

    Cortical columns associated with barrels in layer IV of the somatosensory cortex were characterized by high-resolution 2-deoxy-D-glucose (2DG) autoradiography in freely behaving mice. The method demonstrates a more exact match between columnar labeling and cytoarchitectonic barrel boundaries than previously reported. The pattern of cortical activation seen with stimulation of a single whisker (third whisker in the middle row of large hairs--C3) was compared with the patterns from two control conditions--normal animals with all whiskers present ("positive control")--and with all large whiskers clipped ("negative control"). Two types of measurements were made from 2DG autoradiograms of tangential cortical sections: 1) labeled cells were identified by eye and tabulated with a computer, and 2) grain densities were obtained automatically with a computer-controlled microscope and image processor. We studied the fine-grained patterns of 2DG labeling in a nine-barrel grid with the C3 barrel in the center. From the analysis we draw five major conclusions. 1. Approximately 30-40% of the total number of neurons in the C3 barrel column are activated when only the C3 whisker is stimulated. This is about twice the number of neurons labeled in the C3 column when all whiskers are stimulated and about ten times the number of neurons labeled when all large whiskers are clipped. 2. There is evidence for a vertical functional organization within a barrel-related whisker column which has smaller dimensions in the tangential direction than a barrel. There are densely labeled patches within a barrel which are unique to an individual cortex. The same patchy pattern is found in the appropriate regions of sections above and below the barrels through the full thickness of the cortex. This functional arrangement could be considered to be a "minicolumn" or more likely a group of "minicolumns" (Mountcastle: In G.M. Edelman and U.B. Mountcastle (eds): The Material Brain: Cortical Organization

  18. Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities at surface monitoring sites

    Directory of Open Access Journals (Sweden)

    I. Morino

    2010-08-01

    Full Text Available Remotely operable compact instruments for measuring atmospheric CO2 and CH4 column densities were developed in two independent systems: one utilizing a grating-based desktop optical spectrum analyzer (OSA with a resolution enough to resolve rotational lines of CO2 and CH4 in the regions of 1565–1585 and 1674–1682 nm, respectively; the other is an application of an optical fiber Fabry-Perot interferometer (FFPI to obtain the CO2 column density. Direct sunlight was collimated via a small telescope installed on a portable sun tracker and then transmitted through an optical fiber into the OSA or the FFPI for optical analysis. The near infrared spectra of the OSA were retrieved by a least squares spectral fitting algorithm. The CO2 and CH4 column densities deduced were in excellent agreement with those measured by a Fourier transform spectrometer with high resolution. The rovibronic lines in the wavelength region of 1570–1575 nm were analyzed by the FFPI. The I0 and I values in the Beer-Lambert law equation to obtain CO2 column density were deduced by modulating temperature of the FFPI, which offered column CO2 with the statistical error less than 0.2% for six hours measurement.

  19. Scalability of pre-packed preparative chromatography columns with different diameters and lengths taking into account extra column effects.

    Science.gov (United States)

    Schweiger, Susanne; Jungbauer, Alois

    2018-02-16

    Small pre-packed columns are commonly used to estimate the optimum run parameters for pilot and production scale. The question arises if the experiments obtained with these columns are scalable, because there are substantial changes in extra column volume when going from a very small scale to a benchtop column. In this study we demonstrate the scalability of pre-packed disposable and non-disposable columns of volumes in the range of 0.2-20 ml packed with various media using superficial velocities in the range of 30-500 cm/h. We found that the relative contribution of extra column band broadening to total band broadening was not only high for columns with small diameters, but also for columns with a larger volume due to their wider diameter. The extra column band broadening can be more than 50% for columns with volumes larger than 10 ml. An increase in column diameter leads to high additional extra column band broadening in the filter, frits, and adapters of the columns. We found a linear relationship between intra column band broadening and column length, which increased stepwise with increases in column diameter. This effect was also corroborated by CFD simulation. The intra column band broadening was the same for columns packed with different media. An empirical engineering equation and the data gained from the extra column effects allowed us to predict the intra, extra, and total column band broadening just from column length, diameter, and flow rate. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

  20. Comparison of LC Columns Packed with 2.6 lm Core-Shell and Sub-2 lm Porous Particles for Gradient Separation of Antibiotics

    Czech Academy of Sciences Publication Activity Database

    Tylová, Tereza; Kameník, Zdeněk; Flieger, Miroslav; Olšovská, Jana

    2011-01-01

    Roč. 74, 1-2 (2011), s. 19-27 ISSN 0009-5893 R&D Projects: GA MŠk 1M06011 Institutional research plan: CEZ:AV0Z50200510 Keywords : Column liquid chromatography * Sub-2 mu m particles * Acquity BEH C18 column Subject RIV: EE - Microbiology, Virology Impact factor: 1.195, year: 2011

  1. Dynamics and Control of Distillation Columns - A Critical Survey

    Directory of Open Access Journals (Sweden)

    Sigurd Skogestad

    1997-07-01

    Full Text Available Distillation column dynamics and control have been viewed by many as a very mature or even dead field. However, as is discussed in this paper significant new results have appeared over the last 5-10 years. These results include multiple steady states and instability in simple columns with ideal thermodynamics (which was believed to be impossible, the understanding of the difference between various control configurations and the systematic transformation between these, the feasibility of using the distillate-bottom structure, for control (which was believed to be impossible, the importance of flow dynamics for control studies, the fundamental problems in identifying models from open-loops responses, the use of simple regression estimators to estimate composition from temperatures, and an improved general understanding of the dynamic behavior of distillation columns which includes a better understanding of the fundamental difference between internal and external flow, simple formulas for estimating the dominant time constant, and a derivation of the linearizing effect of logarithmic transformations. These issues apply to all columns, even for ideal mixtures and simple columns with only two products. In addition, there have been significant advances for cases with complex thermodynamics and complex column configurations. These include the behavior and control of azeotropic distillation columns, and the possible complex dynamics of nonideal mixtures and of interlinked columns. However, both for the simple and more complex cases there are still a number of areas where further research is needed.

  2. On-column reduction of catecholamine quinones in stainless steel columns during liquid chromatography.

    Science.gov (United States)

    Xu, R; Huang, X; Kramer, K J; Hawley, M D

    1995-10-10

    The chromatographic behavior of quinones derived from the oxidation of dopamine and N-acetyldopamine has been studied using liquid chromatography (LC) with both a diode array detector and an electrochemical detector that has parallel dual working electrodes. When stainless steel columns are used, an anodic peak for the oxidation of the catecholamine is observed at the same retention time as a cathodic peak for the reduction of the catecholamine quinone. In addition, the anodic peak exhibits a tail that extends to a second anodic peak for the catecholamine. The latter peak occurs at the normal retention time of the catecholamine. The origin of this phenomenon has been studied and metallic iron in the stainless steel components of the LC system has been found to reduce the quinones to their corresponding catecholamines. The simultaneous appearance of a cathodic peak for the reduction of catecholamine quinone and an anodic peak for the oxidation of the corresponding catecholamine occurs when metallic iron in the exit frit reduces some of the quinones as the latter exits the column. This phenomenon is designated as the "concurrent anodic-cathodic response." It is also observed for quinones of of 3,4-dihydroxybenzoic acid and probably occurs with o- or p-quinones of other dihydroxyphenyl compounds. The use of nonferrous components in LC systems is recommended to eliminate possible on-column reduction of quinones.

  3. EX1004L2 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1004L2: Exploration Indonesia - Bitung...

  4. EX1502L2 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1502L2: Caribbean Exploration (Mapping)...

  5. Long-chain alkylimidazolium ionic liquids, a new class of cationic surfactants coated on ODS columns for anion-exchange chromatography.

    Science.gov (United States)

    Qiu, Hongdeng; Zhang, Qinghua; Chen, Limei; Liu, Xia; Jiang, Shengxiang

    2008-08-01

    Separations of common inorganic anions were carried out on ODS columns coated with two long-chain alkylimidazolium ionic liquids ([C(12)MIm]Br and [C(14)MIm]Br) as new cationic surfactants for ion chromatography. With phthalate buffer solution as the mobile phases and non-suppressed conductivity detection, high column efficiencies and excellent selectivity were obtained in the separation of inorganic anions. Chromatographic parameters are calculated and the results show that the coated column possesses significant potential for the analysis of some inorganic anions such as CH(3)COO(-), IO(3)(-), Cl(-), BrO(3)(-), NO(2)(-), Br(-), NO(3)(-), SO(4)(2-), I(-), BF(4)(-), and SCN(-). The effect of eluent pH values on the separation of anions has been studied on the column coated with [C(12)MIm]Br. The stability of the coated columns was also examined.

  6. EX1304L2 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1304L2: Northeast U.S. Canyons...

  7. EX0909L2 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX0909L2: Mapping Field Trials - Necker...

  8. A column switching ultrahigh-performance liquid chromatography-tandem mass spectrometry method to determine anandamide and 2-arachidonoylglycerol in plasma samples.

    Science.gov (United States)

    Marchioni, Camila; de Souza, Israel Donizeti; Grecco, Caroline Fernandes; Crippa, José Alexandre; Tumas, Vitor; Queiroz, Maria Eugênia Costa

    2017-05-01

    This study reports a fast, sensitive, and selective column switching ultrahigh-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method to determine the endocannabinoids (eCBs), anandamide (AEA), and 2-arachidonoylglycerol (2-AG) in plasma samples. This bidimensional system used a restricted access media column (RP-8 ADS, 25 mm × 4 mm × 25 μM) in the first dimension and a core-shell Kinetex C18 (100 mm × 2, 1.7 mm × 1 μM) column in the second dimension, followed by detection in a mass spectrometer triple quadrupole (multiple reactions monitoring mode) operating in the positive mode. RP-8 ADS was used for trace enrichment of eCBs (reverse phase partitioning) and macromolecular matrix size exclusion; the core-shell column was used for the chromatographic separation. The column switching UHPLC-MS/MS method presented a linear range spanning from 0.1 ng mL -1 (LOQ) to 6 ng mL -1 for AEA and from 0.04 ng mL -1 (LOQ) to 10 ng mL -1 for 2-AG. Excluding the LLOQ values, the precision assays provided coefficients of variation lower than 8% and accuracy with relative standard error values lower than 14%. Neither carryover nor matrix effects were detected. This high-throughput column switching method compared to conventional methods is time saving as it involves fewer steps, consumes less solvent, and presents lower LLOQ. The column switching UHPLC-MS/MS method was successfully applied to determine AEA and 2-AG in plasma samples obtained from Alzheimer's disease patients. Graphical abstract A column switching ultra high-performance liquid chromatography-tandem mass spectrometry method using RP-8 ADS column and core shell column to determine endocannabinoids in plasma samples.

  9. Tropospheric nitrogen dioxide column retrieval based on ground-based zenith-sky DOAS observations

    Science.gov (United States)

    Tack, F. M.; Hendrick, F.; Pinardi, G.; Fayt, C.; Van Roozendael, M.

    2013-12-01

    A retrieval approach has been developed to derive tropospheric NO2 vertical column amounts from ground-based zenith-sky measurements of scattered sunlight. Zenith radiance spectra are observed in the visible range by the BIRA-IASB Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instrument and analyzed by the DOAS technique, based on a least-squares spectral fitting. In recent years, this technique has shown to be a well-suited remote sensing tool for monitoring atmospheric trace gases. The retrieval algorithm is developed and validated based on a two month dataset acquired from June to July 2009 in the framework of the Cabauw (51.97° N, 4.93° E) Intercomparison campaign for Nitrogen Dioxide measuring Instruments (CINDI). Once fully operational, the retrieval approach can be applied to observations from stations of the Network for the Detection of Atmospheric Composition Change (NDACC). The obtained tropospheric vertical column amounts are compared with the multi-axis retrieval from the BIRA-IASB MAX-DOAS instrument and the retrieval from a zenith-viewing only SAOZ instrument (Système d'Analyse par Observations Zénithales), owned by Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS). First results show a good agreement for the whole time series with the multi-axis retrieval (R = 0.82; y = 0.88x + 0.30) as well as with the SAOZ retrieval (R = 0.85; y = 0.76x + 0.28 ). Main error sources arise from the uncertainties in the determination of tropospheric and stratospheric air mass factors, the stratospheric NO2 abundances and the residual amount in the reference spectrum. However zenith-sky measurements have been commonly used over the last decades for stratospheric monitoring, this study also illustrates the suitability for retrieval of tropospheric column amounts. As there are long time series of zenith-sky acquisitions available, the developed approach offers new perspectives with regard to the use of observations from the NDACC

  10. Column properties and flow profiles of a flat, wide column for high-pressure liquid chromatography.

    Science.gov (United States)

    Mriziq, Khaled S; Guiochon, Georges

    2008-04-11

    The design and the construction of a pressurized, flat, wide column for high-performance liquid chromatography (HPLC) are described. This apparatus, which is derived from instruments that implement over-pressured thin layer chromatography, can carry out only uni-dimensional chromatographic separations. However, it is intended to be the first step in the development of more powerful instruments that will be able to carry out two-dimensional chromatographic separations, in which case, the first separation would be a space-based separation, LC(x), taking place along one side of the bed and the second separation would be a time-based separation, LC(t), as in classical HPLC but proceeding along the flat column, not along a tube. The apparatus described consists of a pressurization chamber made of a Plexiglas block and a column chamber made of stainless steel. These two chambers are separated by a thin Mylar membrane. The column chamber is a cavity which is filled with a thick layer (ca. 1mm) of the stationary phase. Suitable solvent inlet and outlet ports are located on two opposite sides of the sorbent layer. The design allows the preparation of a homogenous sorbent layer suitable to be used as a chromatographic column, the achievement of effective seals of the stationary phase layer against the chamber edges, and the homogenous flow of the mobile phase along the chamber. The entire width of the sorbent layer area can be used to develop separations or elute samples. The reproducible performance of the apparatus is demonstrated by the chromatographic separations of different dyes. This instrument is essentially designed for testing detector arrays to be used in a two-dimensional LC(x) x LC(t) instrument. The further development of two-dimension separation chromatographs based on the apparatus described is sketched.

  11. EX1605L2 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1605L2: CAPSTONE CNMI and Mariana Trench...

  12. EX1402L2 Water Column Summary Report and Profile Data Collection

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A complete set of water column profile data and CTD Summary Report (if generated) generated by the Okeanos Explorer during EX1402L2: Gulf of Mexico Mapping and...

  13. Compact electron beam focusing column

    Science.gov (United States)

    Persaud, Arun; Leung, Ka-Ngo; Reijonen, Jani

    2001-12-01

    A novel design for an electron beam focusing column has been developed at LBNL. The design is based on a low-energy spread multicusp plasma source which is used as a cathode for electron beam production. The focusing column is 10 mm in length. The electron beam is focused by means of electrostatic fields. The column is designed for a maximum voltage of 50 kV. Simulations of the electron trajectories have been performed by using the 2D simulation code IGUN and EGUN. The electron temperature has also been incorporated into the simulations. The electron beam simulations, column design and fabrication will be discussed in this presentation.

  14. Development of spent salt treatment technology by zeolite column system. Performance evaluation of zeolite column

    International Nuclear Information System (INIS)

    Miura, Hidenori; Uozumi, Koichi

    2009-01-01

    At electrorefining process, fission products(FPs) accumulate in molten salt. To avoid influence on heating control by decay heat and enlargement of FP amount in the recovered fuel, FP elements must be removed from the spent salt of the electrorefining process. For the removal of the FPs from the spent salt, we are investigating the availability of zeolite column system. For obtaining the basic data of the column system, such as flow property and ion-exchange performance while high temperature molten salt is passing through the column, and experimental apparatus equipped with fraction collector was developed. By using this apparatus, following results were obtained. 1) We cleared up the flow parameter of column system with zeolite powder, such as flow rate control by argon pressure. 2) Zeolite 4A in the column can absorb cesium that is one of the FP elements in molten salt. From these results, we got perspective on availability of the zeolite column system. (author)

  15. Bi-axial M-. Phi. analyses of RC columns using fiber model and comparison with experimental results. 2 jikumage wo ukeru hashirabuzai no M-. Phi. kankei eno fiber model no tekigosei

    Energy Technology Data Exchange (ETDEWEB)

    Murayama, Y.; Tokuyama, S.; Furuichi, K. (Kajima Corp., Tokyo (Japan))

    1991-10-31

    In order to examine the accuracy of a fiber model for analyzing the stability of towers of a cable-stayed bridge subjected to biaxial bending force due to earthquake, experimental results of column test specimens were compared with analytical results. The relation between biaxial bending moment and curvature (M-{Phi}) was measured in biaxial bending model experiment using a reinforcement ratio, axial compressive force and loading pattern as parameters. Since the relation was greatly affected by axial modeling of a reinforcing material, the parameter analysis was conducted by paying particular attention to reinforcement models (bilinear model, cubic one and Ramberg-Osgood one). As a result, the Ramberg-Osgood model was suitable for columns with a large longitudinal reinforcement ratio and large axial tension such as seen in highrise buildings, while the cubic model was more suitable for columns with a small ratio such as seen in cable-stayed bridges. 4 refs., 10 figs., 1 tab.

  16. Consistent deformations of dual formulations of linearized gravity: A no-go result

    International Nuclear Information System (INIS)

    Bekaert, Xavier; Boulanger, Nicolas; Henneaux, Marc

    2003-01-01

    The consistent, local, smooth deformations of the dual formulation of linearized gravity involving a tensor field in the exotic representation of the Lorentz group with Young symmetry type (D-3,1) (one column of length D-3 and one column of length 1) are systematically investigated. The rigidity of the Abelian gauge algebra is first established. We next prove a no-go theorem for interactions involving at most two derivatives of the fields

  17. Very high column density and small reddening toward GRB 020124 at z=3.20

    DEFF Research Database (Denmark)

    Hjorth, J.; Møller, Per; Gorosabel, J.

    2003-01-01

    We present optical and near-infrared observations of the dim afterglow of GRB 020124, obtained between 2 and 68 hr after the gamma-ray burst. The burst occurred in a very faint (Rgreater than or similar to29.5) damped Lyalpha absorber (DLA) at a redshift of z=3.198+/-0.004. The derived column...

  18. Assembly for connecting the column ends of two capillary columns

    International Nuclear Information System (INIS)

    Kolb, B.; Auer, M.; Pospisil, P.

    1984-01-01

    In gas chromatography, the column ends of two capillary columns are inserted into a straight capillary from both sides forming annular gaps. The capillary is located in a tee out of which the capillary columns are sealingly guided, and to which carrier gas is supplied by means of a flushing flow conduit. A ''straight-forward operation'' having capillary columns connected in series and a ''flush-back operation'' are possible. The dead volume between the capillary columns can be kept small

  19. 40 CFR Table 25 to Subpart G of... - Effective Column Diameter (Fc)

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 9 2010-07-01 2010-07-01 false Effective Column Diameter (Fc) 25 Table..., Table 25 Table 25 to Subpart G of Part 63—Effective Column Diameter (Fc) Column type Fc (feet) 9-inch by 7-inch built-up columns 1.1 8-inch-diameter pipe columns 0.7 No construction details known 1.0 ...

  20. An analysis of the global spatial variability of column-averaged CO2 from SCIAMACHY and its implications for CO2 sources and sinks

    Science.gov (United States)

    Zhang, Zhen; Jiang, Hong; Liu, Jinxun; Zhang, Xiuying; Huang, Chunlin; Lu, Xuehe; Jin, Jiaxin; Zhou, Guomo

    2014-01-01

    Satellite observations of carbon dioxide (CO2) are important because of their potential for improving the scientific understanding of global carbon cycle processes and budgets. We present an analysis of the column-averaged dry air mole fractions of CO2 (denoted XCO2) of the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) retrievals, which were derived from a satellite instrument with relatively long-term records (2003–2009) and with measurements sensitive to the near surface. The spatial-temporal distributions of remotely sensed XCO2 have significant spatial heterogeneity with about 6–8% variations (367–397 ppm) during 2003–2009, challenging the traditional view that the spatial heterogeneity of atmospheric CO2 is not significant enough (2 and surface CO2 were found for major ecosystems, with the exception of tropical forest. In addition, when compared with a simulated terrestrial carbon uptake from the Integrated Biosphere Simulator (IBIS) and the Emissions Database for Global Atmospheric Research (EDGAR) carbon emission inventory, the latitudinal gradient of XCO2 seasonal amplitude was influenced by the combined effect of terrestrial carbon uptake, carbon emission, and atmospheric transport, suggesting no direct implications for terrestrial carbon sinks. From the investigation of the growth rate of XCO2 we found that the increase of CO2 concentration was dominated by temperature in the northern hemisphere (20–90°N) and by precipitation in the southern hemisphere (20–90°S), with the major contribution to global average occurring in the northern hemisphere. These findings indicated that the satellite measurements of atmospheric CO2 improve not only the estimations of atmospheric inversion, but also the understanding of the terrestrial ecosystem carbon dynamics and its feedback to atmospheric CO2.

  1. Robust naphthyl methacrylate monolithic column for high performance liquid chromatography of a wide range of solutes.

    Science.gov (United States)

    Jonnada, Murthy; El Rassi, Ziad

    2015-08-28

    An organic monolithic column based on the co-polymerization of 2-naphthyl methacrylate (NAPM) as the functional monomer and trimethylolpropane trimethacrylate (TRIM) as the crosslinker was introduced for high performance reversed-phase liquid chromatography (RPC). The co-polymerization was performed in situ in a stainless steel column of 4.6mm i.d. in the presence of a ternary porogen consisting of 1-dodecanol and cyclohexanol. This monolithic column (referred to as naphthyl methacrylate monolithic column or NMM column) showed high mechanical stability at relatively high mobile phase flow velocity indicating that the column has excellent hydrodynamic characteristics. To characterize the NMM column, different probe molecules including alkyl benzenes, and aniline, benzene, toluene and phenol derivatives were chromatographed on the column and the results in terms of k, selectivity and plate counts were compared to those obtained on an octadecyl silica (ODS) column in order to assess the presence of π-π and hydrophobic interactions on the NMM column under otherwise the same elution conditions. The NMM column offered additional π-π interactions with aromatic molecules in addition to hydrophobic interactions under RPC elution conditions. Run-to-run and column-to-column reproducibility of solute k values were evaluated, and percent relative standard deviation of column using shallow (30min at 1.0mL/min), steep (10min at 1.0mL/min) and ultra steep (1min at 3.0mL/min) linear gradient elution at increasing ACN concentration in the mobile phase using a 10cm×4.6mm i.d. column in case of shallow and steep linear gradients and a 3cm×4.6mm i.d. column for ultra steep linear gradient. Copyright © 2015 Elsevier B.V. All rights reserved.

  2. Materials performance in prototype Thermal Cycling Absorption Process (TCAP) columns

    International Nuclear Information System (INIS)

    Clark, E.A.

    1992-01-01

    Two prototype Thermal Cycling Absorption Process (TCAP) columns have been metallurgically examined after retirement, to determine the causes of failure and to evaluate the performance of the column container materials in this application. Leaking of the fluid heating and cooling subsystems caused retirement of both TCAP columns, not leaking of the main hydrogen-containing column. The aluminum block design TCAP column (AHL block TCAP) used in the Advanced Hydride Laboratory, Building 773-A, failed in one nitrogen inlet tube that was crimped during fabrication, which lead to fatigue crack growth in the tube and subsequent leaking of nitrogen from this tube. The Third Generation stainless steel design TCAP column (Third generation TCAP), operated in 773-A room C-061, failed in a braze joint between the freon heating and cooling tubes (made of copper) and the main stainless steel column. In both cases, stresses from thermal cycling and local constraint likely caused the nucleation and growth of fatigue cracks. No materials compatibility problems between palladium coated kieselguhr (the material contained in the TCAP column) and either aluminum or stainless steel column materials were observed. The aluminum-stainless steel transition junction appeared to be unaffected by service in the AHL block TCAP. Also, no evidence of cracking was observed in the AHL block TCAP in a location expected to experience the highest thermal shock fatigue in this design. It is important to limit thermal stresses caused by constraint in hydride systems designed to work by temperature variation, such as hydride storage beds and TCAP columns

  3. Deposition of gamma emitters from Chernobyl accident and their transfer in lichen-soil columns.

    Science.gov (United States)

    Lehto, Jukka; Paatero, Jussi; Pehrman, Reijo; Kulmala, Seija; Suksi, Juhani; Koivula, Teija; Jaakkola, Timo

    2008-10-01

    Lichen-soil column samples were taken from several locations in the Southern Finland between 1986 and 2006. Columns were divided into three parts, upper lichen, lower lichen and underlying soil, and their gamma emitting radionuclides, 134Cs, 137Cs, 103Ru, 95Zr, 106Ru, 110mAg, 125Sb and 144Ce, were measured with gamma spectrometry. Deposition values were calculated as Bq/m2 for each sampling site. Distribution of various radionuclides in the three compartments as a function of time was determined. Both effective and ecological half-lives of all radionuclides were calculated for upper lichen, whole lichen and whole lichen-soil column. A linear relation was derived between the physical half-lives and effective half-lives for whole lichen and for whole lichen-soil column. Reindeer meat activity concentrations of various radionuclides and ensuing radiation doses to reindeer-herding people were also estimated for a hypothetical case where a similar high radioactive pollution, as was taken place in the Southern Finland, would have occurred in the reindeer-herding areas in the Finnish Lapland.

  4. Picobubble enhanced column flotation of fine coal

    Energy Technology Data Exchange (ETDEWEB)

    Tao, D.; Yu, S.; Parekh, B.K. [University of Kentucky, Lexington, KY (United States). Mining Engineering

    2006-07-01

    The purpose is to study the effectiveness of picobubbles in the column flotation of -28 mesh fine coal particles. A flotation column with a picobubble generator was developed and tested for enhancing the recovery of ultrafine coal particles. The picobubble generator was designed using the hydrodynamic cavitation principle. A metallurgical and a steam coal were tested in the apparatus. The results show that the use of picobubbles in a 2in. flotation column increased the recovery of fine coal by 10 to 30%. The recovery rate varied with feed rate, collector dosage, and other column conditions. 40 refs., 8 figs., 2 tabs.

  5. Remote sensing of stratospheric O3 and NO2 using a portable and compact DOAS spectrometer

    International Nuclear Information System (INIS)

    Raponi, M M; Wolfram, E; Quel, E J; Jimenez, R; Tocho, J O

    2011-01-01

    The use of passive and active remote sensing systems has largely contributed to advance our understanding of important atmospheric phenomena. Here we present a compact and portable passive DOAS (Differential Optical Absorption Spectroscopy) system, developed for measuring the vertical column density (VCD) of multiple atmospheric trace gases. We highlight the main characteristics of the system components: a mini-spectrometer (HR4000, Ocean Optics), two optical fibers (400 μm of core, 6 m and 25 cm of longitude), an external shutter and the control/data processing software. Nitrogen dioxide (NO 2 ) and ozone (O 3 ) VCDs are derived from solar spectra acquired during twilights (87 0 - 91 0 zenithal angles) using the DOAS technique. The analysis is carried out by solving the Beer-Lambert-Bouger (BLB) law for the main atmospheric absorbers at selected wavelength ranges. The algorithm minimizes the fitting residuals to the BLB law, having as unknown the slant column density (SCD) of the species to determine. We present measurements carried out at the Marambio Antarctic Base (64 0 14' 25'' S; 56 0 37' 21'' W, 197 m asl) during January - February 2008. In addition, we compare our results with co-located measurements performed with EVA, a visible absorption spectrometer of Instituto Nacional de Tecnica Aeroespacial (INTA, Spain), a Dobson spectrophotometer of Servicio Meteorologico Nacional (SMN, Argentine) and the Ozone Monitoring Instrument (OMI), on board AURA satellite.

  6. Automation of column-based radiochemical separations. A comparison of fluidic, robotic, and hybrid architectures

    Energy Technology Data Exchange (ETDEWEB)

    Grate, J.W.; O' Hara, M.J.; Farawila, A.F.; Ozanich, R.M.; Owsley, S.L. [Pacific Northwest National Laboratory, Richland, WA (United States)

    2011-07-01

    Two automated systems have been developed to perform column-based radiochemical separation procedures. These new systems are compared with past fluidic column separation architectures, with emphasis on using disposable components so that no sample contacts any surface that any other sample has contacted, and setting up samples and columns in parallel for subsequent automated processing. In the first new approach, a general purpose liquid handling robot has been modified and programmed to perform anion exchange separations using 2 mL bed columns in 6 mL plastic disposable column bodies. In the second new approach, a fluidic system has been developed to deliver clean reagents through disposable manual valves to six disposable columns, with a mechanized fraction collector that positions one of four rows of six vials below the columns. The samples are delivered to each column via a manual 3-port disposable valve from disposable syringes. This second approach, a hybrid of fluidic and mechanized components, is a simpler more efficient approach for performing anion exchange procedures for the recovery and purification of plutonium from samples. The automation architectures described can also be adapted to column-based extraction chromatography separations. (orig.)

  7. Estimates of Lightning NOx Production Based on OMI NO2 Observations Over the Gulf of Mexico

    Science.gov (United States)

    Pickering, Kenneth E.; Bucsela, Eric; Allen, Dale; Ring, Allison; Holzworth, Robert; Krotkov, Nickolay

    2016-01-01

    We evaluate nitrogen oxide (NO(sub x) NO + NO2) production from lightning over the Gulf of Mexico region using data from the Ozone Monitoring Instrument (OMI) aboard NASAs Aura satellite along with detection efficiency-adjusted lightning data from the World Wide Lightning Location Network (WWLLN). A special algorithm was developed to retrieve the lightning NOx [(LNO(sub x)] signal from OMI. The algorithm in its general form takes the total slant column NO2 from OMI and removes the stratospheric contribution and tropospheric background and includes an air mass factor appropriate for the profile of lightning NO(sub x) to convert the slant column LNO2 to a vertical column of LNO(sub x). WWLLN flashes are totaled over a period of 3 h prior to OMI overpass, which is the time an air parcel is expected to remain in a 1 deg. x 1 deg. grid box. The analysis is conducted for grid cells containing flash counts greater than a threshold value of 3000 flashes that yields an expected LNO(sub x) signal greater than the background. Pixels with cloud radiance fraction greater than a criterion value (0.9) indicative of highly reflective clouds are used. Results for the summer seasons during 2007-2011 yield mean LNO(sub x) production of approximately 80 +/- 45 mol per flash over the region for the two analysis methods after accounting for biases and uncertainties in the estimation method. These results are consistent with literature estimates and more robust than many prior estimates due to the large number of storms considered but are sensitive to several substantial sources of uncertainty.

  8. Highly sensitive determination of 2,4,6-trinitrotoluene and related byproducts using a diol functionalized column for high performance liquid chromatography.

    Science.gov (United States)

    Gumuscu, Burcu; Erdogan, Zeynep; Guler, Mustafa O; Tekinay, Turgay

    2014-01-01

    In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95-98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation.

  9. Tidal variability of CO2 and CH4 emissions from the water column within a Rhizophora mangrove forest (New Caledonia).

    Science.gov (United States)

    Jacotot, Adrien; Marchand, Cyril; Allenbach, Michel

    2018-08-01

    We performed a preliminary study to quantify CO 2 and CH 4 emissions from the water column within a Rhizophora spp. mangrove forest. Mean CO 2 and CH 4 emissions during the studied period were 3.35±3.62mmolCm -2 h -1 and 18.30±27.72μmolCm -2 h -1 , respectively. CO 2 and CH 4 emissions were highly variable and mainly driven by tides (flow/ebb, water column thickness, neap/spring). Indeed, an inverse relationship between the magnitude of the emissions and the thickness of the water column above the mangrove soil was observed. δ 13 CO 2 values ranged from -26.88‰ to -8.6‰, suggesting a mixing between CO 2 -enriched pore waters and lagoon incoming waters. In addition, CO 2 and CH 4 emissions were significantly higher during ebb tides, mainly due to the progressive enrichment of the water column by diffusive fluxes as its residence time over the forest floor increased. Eventually, we observed higher CO 2 and CH 4 emissions during spring tides than during neap tides, combined to depleted δ 13 CO 2 values, suggesting a higher contribution of soil-produced gases to the emissions. These higher emissions may result from higher renewable of the electron acceptor and enhanced exchange surface between the soil and the water column. This study shows that CO 2 and CH 4 emissions from the water column were not negligible and must be considered in future carbon budgets in mangroves. Copyright © 2018 Elsevier B.V. All rights reserved.

  10. Contributions to reversed-phase column selectivity: III. Column hydrogen-bond basicity.

    Science.gov (United States)

    Carr, P W; Dolan, J W; Dorsey, J G; Snyder, L R; Kirkland, J J

    2015-05-22

    Column selectivity in reversed-phase chromatography (RPC) can be described in terms of the hydrophobic-subtraction model, which recognizes five solute-column interactions that together determine solute retention and column selectivity: hydrophobic, steric, hydrogen bonding of an acceptor solute (i.e., a hydrogen-bond base) by a stationary-phase donor group (i.e., a silanol), hydrogen bonding of a donor solute (e.g., a carboxylic acid) by a stationary-phase acceptor group, and ionic. Of these five interactions, hydrogen bonding between donor solutes (acids) and stationary-phase acceptor groups is the least well understood; the present study aims at resolving this uncertainty, so far as possible. Previous work suggests that there are three distinct stationary-phase sites for hydrogen-bond interaction with carboxylic acids, which we will refer to as column basicity I, II, and III. All RPC columns exhibit a selective retention of carboxylic acids (column basicity I) in varying degree. This now appears to involve an interaction of the solute with a pair of vicinal silanols in the stationary phase. For some type-A columns, an additional basic site (column basicity II) is similar to that for column basicity I in primarily affecting the retention of carboxylic acids. The latter site appears to be associated with metal contamination of the silica. Finally, for embedded-polar-group (EPG) columns, the polar group can serve as a proton acceptor (column basicity III) for acids, phenols, and other donor solutes. Copyright © 2015 Elsevier B.V. All rights reserved.

  11. Intensity Modulation Techniques for Continuous-Wave Lidar for Column CO2 Measurements

    Science.gov (United States)

    Campbell, J. F.; Lin, B.; Obland, M. D.; Kooi, S. A.; Fan, T. F.; Meadows, B.; Browell, E. V.; Erxleben, W. H.; McGregor, D.; Dobler, J. T.; Pal, S.; O'Dell, C.

    2017-12-01

    Global and regional atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission and the Atmospheric Carbon and Transport (ACT) - America project are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity-Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space and airborne platforms to meet the ASCENDS and ACT-America science measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) and Linear Swept Frequency modulations to uniquely discriminate surface lidar returns from intermediate aerosol and cloud returns. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby eliminating bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that take advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques and provides very high (at sub-meter level) range resolution. We compare BPSK to linear swept frequency and introduce a new technique to eliminate sidelobes in situations from linear swept frequency where the SNR is high with results that rival BPSK. We also investigate the effects of non-linear modulators, which can in some circumstances degrade the orthogonality of the waveforms, and show how to avoid this. These techniques are used in a new data processing architecture written in

  12. Reliability of a four-column classification for tibial plateau fractures.

    Science.gov (United States)

    Martínez-Rondanelli, Alfredo; Escobar-González, Sara Sofía; Henao-Alzate, Alejandro; Martínez-Cano, Juan Pablo

    2017-09-01

    A four-column classification system offers a different way of evaluating tibial plateau fractures. The aim of this study is to compare the intra-observer and inter-observer reliability between four-column and classic classifications. This is a reliability study, which included patients presenting with tibial plateau fractures between January 2013 and September 2015 in a level-1 trauma centre. Four orthopaedic surgeons blindly classified each fracture according to four different classifications: AO, Schatzker, Duparc and four-column. Kappa, intra-observer and inter-observer concordance were calculated for the reliability analysis. Forty-nine patients were included. The mean age was 39 ± 14.2 years, with no gender predominance (men: 51%; women: 49%), and 67% of the fractures included at least one of the posterior columns. The intra-observer and inter-observer concordance were calculated for each classification: four-column (84%/79%), Schatzker (60%/71%), AO (50%/59%) and Duparc (48%/58%), with a statistically significant difference among them (p = 0.001/p = 0.003). Kappa coefficient for intr-aobserver and inter-observer evaluations: Schatzker 0.48/0.39, four-column 0.61/0.34, Duparc 0.37/0.23, and AO 0.34/0.11. The proposed four-column classification showed the highest intra and inter-observer agreement. When taking into account the agreement that occurs by chance, Schatzker classification showed the highest inter-observer kappa, but again the four-column had the highest intra-observer kappa value. The proposed classification is a more inclusive classification for the posteromedial and posterolateral fractures. We suggest, therefore, that it be used in addition to one of the classic classifications in order to better understand the fracture pattern, as it allows more attention to be paid to the posterior columns, it improves the surgical planning and allows the surgical approach to be chosen more accurately.

  13. JCE Feature Columns

    Science.gov (United States)

    Holmes, Jon L.

    1999-05-01

    The Features area of JCE Online is now readily accessible through a single click from our home page. In the Features area each column is linked to its own home page. These column home pages also have links to them from the online Journal Table of Contents pages or from any article published as part of that feature column. Using these links you can easily find abstracts of additional articles that are related by topic. Of course, JCE Online+ subscribers are then just one click away from the entire article. Finding related articles is easy because each feature column "site" contains links to the online abstracts of all the articles that have appeared in the column. In addition, you can find the mission statement for the column and the email link to the column editor that I mentioned above. At the discretion of its editor, a feature column site may contain additional resources. As an example, the Chemical Information Instructor column edited by Arleen Somerville will have a periodically updated bibliography of resources for teaching and using chemical information. Due to the increase in the number of these resources available on the WWW, it only makes sense to publish this information online so that you can get to these resources with a simple click of the mouse. We expect that there will soon be additional information and resources at several other feature column sites. Following in the footsteps of the Chemical Information Instructor, up-to-date bibliographies and links to related online resources can be made available. We hope to extend the online component of our feature columns with moderated online discussion forums. If you have a suggestion for an online resource you would like to see included, let the feature editor or JCE Online (jceonline@chem.wisc.edu) know about it. JCE Internet Features JCE Internet also has several feature columns: Chemical Education Resource Shelf, Conceptual Questions and Challenge Problems, Equipment Buyers Guide, Hal's Picks, Mathcad

  14. Conventional and narrow bore short capillary columns with cyclodextrin derivatives as chiral selectors to speed-up enantioselective gas chromatography and enantioselective gas chromatography-mass spectrometry analyses.

    Science.gov (United States)

    Bicchi, Carlo; Liberto, Erica; Cagliero, Cecilia; Cordero, Chiara; Sgorbini, Barbara; Rubiolo, Patrizia

    2008-11-28

    The analysis of complex real-world samples of vegetable origin requires rapid and accurate routine methods, enabling laboratories to increase sample throughput and productivity while reducing analysis costs. This study examines shortening enantioselective-GC (ES-GC) analysis time following the approaches used in fast GC. ES-GC separations are due to a weak enantiomer-CD host-guest interaction and the separation is thermodynamically driven and strongly influenced by temperature. As a consequence, fast temperature rates can interfere with enantiomeric discrimination; thus the use of short and/or narrow bore columns is a possible approach to speeding-up ES-GC analyses. The performance of ES-GC with a conventional inner diameter (I.D.) column (25 m length x 0.25 mm I.D., 0.15 microm and 0.25 microm d(f)) coated with 30% of 2,3-di-O-ethyl-6-O-tert-butyldimethylsilyl-beta-cyclodextrin in PS-086 is compared to those of conventional I.D. short column (5m length x 0.25 mm I.D., 0.15 microm d(f)) and of different length narrow bore columns (1, 2, 5 and 10 m long x 0.10 mm I.D., 0.10 microm d(f)) in analysing racemate standards of pesticides and in the flavour and fragrance field and real-world-samples. Short conventional I.D. columns gave shorter analysis time and comparable or lower resolutions with the racemate standards, depending mainly on analyte volatility. Narrow-bore columns were tested under different analysis conditions; they provided shorter analysis time and resolutions comparable to those of conventional I.D. ES columns. The narrow-bore columns offering the most effective compromise between separation efficiency and analysis time are the 5 and 2m columns; in combination with mass spectrometry as detector, applied to lavender and bergamot essential oil analyses, these reduced analysis time by a factor of at least three while separation of chiral markers remained unaltered.

  15. Study on application of single-crystal ice `Kurobe ice column` to high-speed skating rinks. Demonstration test result at Olympic memorial arena `M wave` in Nagano city; Tankesshohyo `Kurobe no hyojun` no kosoku skate link eno tekiyosei kenkyu. Naganoshi olympic kinen arina `Emu Wave` deno jissho shiken kekka

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, M. [Kansai Electric Power Co. Inc., Osaka (Japan)

    1999-06-10

    For high-speed low-friction skating rinks, research was made on sticking artificial ice columns (ice bamboo shoot). The ice columns were fabricated with the ice column production equipment equipped with 4-line water droplet dropping devices which were installed at intervals of 0.3m on both sides of a pathway of 200m long, 2.6m wide and 1.8m high in the lateral adit of Kurobegawa No.4 hydroelectric power station. The grown ice columns were processed for high-speed skating rinks through cutting, confirmation of single crystal and crystal orientation, slicing for every 7mm thickness and packaging. The ice columns were spread all over the rink while sliding them to prevent mixing of bubbles after spraying distilled water of nearly 25 degreesC onto base ices. In addition, hot water of nearly 40 degreesC was sprayed to produce the final ice rink of 30mm thick by nearly 5mm a day. The dynamic friction coefficient of the ice column rink reduced to 0.0038 by nearly 16% as compared with 0.0045 of conventional rinks. (NEDO)

  16. Rotation of a magnesium plasma column in a background gas

    International Nuclear Information System (INIS)

    Bosco, E. Del; Dallaqua, R.S.

    1993-01-01

    Measurements of the angular velocity of a plasma column in a surrounding gas atmosphere are presented. The plasma is produced by a pulsed, high current arc discharge in the presence of an axial magnetic field. The angular velocity is measured using the cross correlation technique applied to the floating potential signals measured by two Langmuir probes. The main result is that when gas is added to the discharge the angular velocity is always lower than the case when there is no gas, this effect been more pronounced in the beginning of the discharge. For pressures higher than ∼ 2 x 10 -2 Pa there is a effect of the gas on the plasma column rotation and the angular velocity diminishes even at the end of discharge. (author)

  17. Impact Analysis of Reinforced Concrete Columns with Side Openings Subjected to Eccentric Axial Loads

    Directory of Open Access Journals (Sweden)

    Nazar Kamil Ali

    2015-02-01

    Full Text Available In this research the behavior of reinforced concrete columns with large side openings under impact loads was studied. The overall cross sectional dimensions of the column specimens used in this research were (500*1400 mm with total height of (14000 mm. The dimensions of side openings were (600*2000 mm. The column was reinforced with (20 mm diameter in longitudinal direction, while (12 mm ties were used in the transverse direction. The effect of eccentric impact loads on the horizontal and vertical displacement for this column was studied. Nonlinear finite element analysis has been carried out using ready computer finite element package (ANSYS to simulate the behavior of the reinforced concrete column with large side openings. Two load cases were considered in this investigation (C1, C2 with three different load values for each case. In the first case (C1 the loads was applied to one side of the column and in the second case (C2 the loads was applied to both sides. An Equilateral triangular load-time function was used for simulation the impact load results from gantry cranes supported by the column with total time duration (0.1 sec. In order to verify the analysis method, as no experimental data exist for comparing the obtained results, another analysis is made for tested conventional column under impact load at mid-height and good agreement has been obtained. For the above mentioned column, the maximum displacements were (33.3, 22.2 mm in the horizontal and longitudinal direction respectively, location of the maximum horizontal displacement was at the crown of the column. By comparing the results of the first loading case with the second one it is shown that in the horizontal direction, maximum displacement increases by (139%, (208%, and (147% respectively, also the maximum vertical displacement increases by (150%, (172%, and (172% respectively.

  18. North Atlantic Aerosol Properties for Radiative Impact Assessments. Derived from Column Closure Analyses in TARFOX and ACE-2

    Science.gov (United States)

    Russell, Philip A.; Bergstrom, Robert A.; Schmid, Beat; Livingston, John M.

    2000-01-01

    Aerosol effects on atmospheric radiative fluxes provide a forcing function that can change the climate in potentially significant ways. This aerosol radiative forcing is a major source of uncertainty in understanding the climate change of the past century and predicting future climate. To help reduce this uncertainty, the 1996 Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) and the 1997 Aerosol Characterization Experiment (ACE-2) measured the properties and radiative effects of aerosols over the Atlantic Ocean. Both experiments used remote and in situ measurements from aircraft and the surface, coordinated with overpasses by a variety of satellite radiometers. TARFOX focused on the urban-industrial haze plume flowing from the United States over the western Atlantic, whereas ACE-2 studied aerosols over the eastern Atlantic from both Europe and Africa. These aerosols often have a marked impact on satellite-measured radiances. However, accurate derivation of flux changes, or radiative forcing, from the satellite measured radiances or retrieved aerosol optical depths (AODs) remains a difficult challenge. Here we summarize key initial results from TARFOX and ACE-2, with a focus on closure analyses that yield aerosol microphysical models for use in improved assessments of flux changes. We show how one such model gives computed radiative flux sensitivities (dF/dAOD) that agree with values measured in TARFOX and preliminary values computed for the polluted marine boundary layer in ACE-2. A companion paper uses the model to compute aerosol-induced flux changes over the North Atlantic from AVHRR-derived AOD fields.

  19. Advanced intensity-modulation continuous-wave lidar techniques for ASCENDS CO2 column measurements

    Science.gov (United States)

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.; Harrison, F. W.; Obland, Michael D.; Meadows, Byron

    2015-10-01

    Global atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity- Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space to meet the ASCENDS measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud contamination. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby eliminating the need to correct for sidelobe bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. A comparison of BPSK and linear swept-frequency is also discussed in this paper. These results are extended to include Richardson-Lucy deconvolution techniques to extend the resolution of the lidar beyond that implied by limit of the bandwidth of the modulation, where it is shown useful for making tree canopy measurements.

  20. Advanced Intensity-Modulation Continuous-Wave Lidar Techniques for ASCENDS O2 Column Measurements

    Science.gov (United States)

    Campbell, Joel F.; Lin, Bing; Nehrir, Amin R.; Harrison, F. Wallace; Obland, Michael D.; Meadows, Byron

    2015-01-01

    Global atmospheric carbon dioxide (CO2) measurements for the NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) space mission are critical for improving our understanding of global CO2 sources and sinks. Advanced Intensity- Modulated Continuous-Wave (IM-CW) lidar techniques are investigated as a means of facilitating CO2 measurements from space to meet the ASCENDS measurement requirements. In recent numerical, laboratory and flight experiments we have successfully used the Binary Phase Shift Keying (BPSK) modulation technique to uniquely discriminate surface lidar returns from intermediate aerosol and cloud contamination. We demonstrate the utility of BPSK to eliminate sidelobes in the range profile as a means of making Integrated Path Differential Absorption (IPDA) column CO2 measurements in the presence of optically thin clouds, thereby eliminating the need to correct for sidelobe bias errors caused by the clouds. Furthermore, high accuracy and precision ranging to the surface as well as to the top of intermediate cloud layers, which is a requirement for the inversion of column CO2 number density measurements to column CO2 mixing ratios, has been demonstrated using new hyperfine interpolation techniques that takes advantage of the periodicity of the modulation waveforms. This approach works well for both BPSK and linear swept-frequency modulation techniques. The BPSK technique under investigation has excellent auto-correlation properties while possessing a finite bandwidth. A comparison of BPSK and linear swept-frequency is also discussed in this paper. These results are extended to include Richardson-Lucy deconvolution techniques to extend the resolution of the lidar beyond that implied by limit of the bandwidth of the modulation, where it is shown useful for making tree canopy measurements.

  1. Flow rate dependent extra-column variance from injection in capillary liquid chromatography.

    Science.gov (United States)

    Aggarwal, Pankaj; Liu, Kun; Sharma, Sonika; Lawson, John S; Dennis Tolley, H; Lee, Milton L

    2015-02-06

    Efficiency and resolution in capillary liquid chromatography (LC) can be significantly affected by extra-column band broadening, especially for isocratic separations. This is particularly a concern in evaluating column bed structure using non-retained test compounds. The band broadening due to an injector supplied with a commercially available capillary LC system was characterized from experimental measurements. The extra-column variance from the injection valve was found to have an extra-column contribution independent of the injection volume, showing an exponential dependence on flow rate. The overall extra-column variance from the injection valve was found to vary from 34 to 23 nL. A new mathematical model was derived that explains this exponential contribution of extra-column variance on chromatographic performance. The chromatographic efficiency was compromised by ∼130% for a non-retained analyte because of injection valve dead volume. The measured chromatographic efficiency was greatly improved when a new nano-flow pumping system with integrated injection valve was used. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Highly Sensitive Determination of 2,4,6-Trinitrotoluene and Related Byproducts Using a Diol Functionalized Column for High Performance Liquid Chromatography

    Science.gov (United States)

    Gumuscu, Burcu; Erdogan, Zeynep; Guler, Mustafa O.; Tekinay, Turgay

    2014-01-01

    In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT); 2,4-dinitrotoluene (2,4-DNT); 2,6-dinitrotoluene (2,6-DNT); 2-aminodinitrotoluene (2-ADNT) and 4-aminodinitrotoluene (4-ADNT) molecules in high-performance liquid-chromatography (HPLC) with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95–98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation. PMID:24905826

  3. Highly sensitive determination of 2,4,6-trinitrotoluene and related byproducts using a diol functionalized column for high performance liquid chromatography.

    Directory of Open Access Journals (Sweden)

    Burcu Gumuscu

    Full Text Available In this work, a new detection method for complete separation of 2,4,6-trinitrotoluene (TNT; 2,4-dinitrotoluene (2,4-DNT; 2,6-dinitrotoluene (2,6-DNT; 2-aminodinitrotoluene (2-ADNT and 4-aminodinitrotoluene (4-ADNT molecules in high-performance liquid-chromatography (HPLC with UV sensor has been developed using diol column. This approach improves on cost, time, and sensitivity over the existing methods, providing a simple and effective alternative. Total analysis time was less than 13 minutes including column re-equilibration between runs, in which water and acetonitrile were used as gradient elution solvents. Under optimized conditions, the minimum resolution between 2,4-DNT and 2,6-DNT peaks was 2.06. The recovery rates for spiked environmental samples were between 95-98%. The detection limits for diol column ranged from 0.78 to 1.17 µg/L for TNT and its byproducts. While the solvent consumption was 26.4 mL/min for two-phase EPA and 30 mL/min for EPA 8330 methods, it was only 8.8 mL/min for diol column. The resolution was improved up to 49% respect to two-phase EPA and EPA 8330 methods. When compared to C-18 and phenyl-3 columns, solvent usage was reduced up to 64% using diol column and resolution was enhanced approximately two-fold. The sensitivity of diol column was afforded by the hydroxyl groups on polyol layer, joining the formation of charge-transfer complexes with nitroaromatic compounds according to acceptor-donor interactions. Having compliance with current requirements, the proposed method demonstrates sensitive and robust separation.

  4. 2-D Row-Column CMUT Arrays with an Open-Grid Support Structure

    DEFF Research Database (Denmark)

    Christiansen, Thomas Lehrmann; Dahl-Petersen, Christian; Jensen, Jørgen Arendt

    2013-01-01

    Fabrication and characterization of 64 + 64 2-D row-column addressed CMUT arrays with 250 μm element pitch and 4.4 MHz center frequency in air incorporating a new design approach is presented. The arrays are comprised of two wafer bonded, structured silicon-on-insulator wafers featuring an opengr...

  5. Influence of pressure on the properties of chromatographic columns. II. The column hold-up volume.

    Science.gov (United States)

    Gritti, Fabrice; Martin, Michel; Guiochon, Georges

    2005-04-08

    The effect of the local pressure and of the average column pressure on the hold-up column volume was investigated between 1 and 400 bar, from a theoretical and an experimental point of view. Calculations based upon the elasticity of the solids involved (column wall and packing material) and the compressibility of the liquid phase show that the increase of the column hold-up volume with increasing pressure that is observed is correlated with (in order of decreasing importance): (1) the compressibility of the mobile phase (+1 to 5%); (2) in RPLC, the compressibility of the C18-bonded layer on the surface of the silica (+0.5 to 1%); and (3) the expansion of the column tube (columns packed with the pure Resolve silica (0% carbon), the derivatized Resolve-C18 (10% carbon) and the Symmetry-C18 (20% carbon) adsorbents, using water, methanol, or n-pentane as the mobile phase. These solvents have different compressibilities. However, 1% of the relative increase of the column hold-up volume that was observed when the pressure was raised is not accounted for by the compressibilities of either the solvent or the C18-bonded phase. It is due to the influence of the pressure on the retention behavior of thiourea, the compound used as tracer to measure the hold-up volume.

  6. An Ensemble Three-Dimensional Constrained Variational Analysis Method to Derive Large-Scale Forcing Data for Single-Column Models

    Science.gov (United States)

    Tang, Shuaiqi

    Atmospheric vertical velocities and advective tendencies are essential as large-scale forcing data to drive single-column models (SCM), cloud-resolving models (CRM) and large-eddy simulations (LES). They cannot be directly measured or easily calculated with great accuracy from field measurements. In the Atmospheric Radiation Measurement (ARM) program, a constrained variational algorithm (1DCVA) has been used to derive large-scale forcing data over a sounding network domain with the aid of flux measurements at the surface and top of the atmosphere (TOA). We extend the 1DCVA algorithm into three dimensions (3DCVA) along with other improvements to calculate gridded large-scale forcing data. We also introduce an ensemble framework using different background data, error covariance matrices and constraint variables to quantify the uncertainties of the large-scale forcing data. The results of sensitivity study show that the derived forcing data and SCM simulated clouds are more sensitive to the background data than to the error covariance matrices and constraint variables, while horizontal moisture advection has relatively large sensitivities to the precipitation, the dominate constraint variable. Using a mid-latitude cyclone case study in March 3rd, 2000 at the ARM Southern Great Plains (SGP) site, we investigate the spatial distribution of diabatic heating sources (Q1) and moisture sinks (Q2), and show that they are consistent with the satellite clouds and intuitive structure of the mid-latitude cyclone. We also evaluate the Q1 and Q2 in analysis/reanalysis, finding that the regional analysis/reanalysis all tend to underestimate the sub-grid scale upward transport of moist static energy in the lower troposphere. With the uncertainties from large-scale forcing data and observation specified, we compare SCM results and observations and find that models have large biases on cloud properties which could not be fully explained by the uncertainty from the large-scale forcing

  7. The effects of carbide column to swelling potential and Atterberg limit on expansive soil with column to soil drainage

    Science.gov (United States)

    Muamar Rifa'i, Alfian; Setiawan, Bambang; Djarwanti, Noegroho

    2017-12-01

    The expansive soil is soil that has a potential for swelling-shrinking due to changes in water content. Such behavior can exert enough force on building above to cause damage. The use of columns filled with additives such as Calcium Carbide is done to reduce the negative impact of expansive soil behavior. This study aims to determine the effect of carbide columns on expansive soil. Observations were made on swelling and spreading of carbides in the soil. 7 Carbide columns with 5 cm diameter and 20 cm height were installed into the soil with an inter-column spacing of 8.75 cm. Wetting is done through a pipe at the center of the carbide column for 20 days. Observations were conducted on expansive soil without carbide columns and expansive soil with carbide columns. The results showed that the addition of carbide column could reduce the percentage of swelling by 4.42%. Wetting through the center of the carbide column can help spread the carbide into the soil. The use of carbide columns can also decrease the rate of soil expansivity. After the addition of carbide column, the plasticity index value decreased from 71.76% to 4.3% and the shrinkage index decreased from 95.72% to 9.2%.

  8. Quantitative atom column position analysis at the incommensurate interfaces of a (PbS)1.14NbS2 misfit layered compound with aberration-corrected HRTEM

    International Nuclear Information System (INIS)

    Garbrecht, M.; Spiecker, E.; Tillmann, K.; Jaeger, W.

    2011-01-01

    Aberration-corrected HRTEM is applied to explore the potential of NCSI contrast imaging to quantitatively analyse the complex atomic structure of misfit layered compounds and their incommensurate interfaces. Using the (PbS) 1.14 NbS 2 misfit layered compound as a model system it is shown that atom column position analyses at the incommensurate interfaces can be performed with precisions reaching a statistical accuracy of ±6 pm. The procedure adopted for these studies compares experimental images taken from compound regions free of defects and interface modulations with a structure model derived from XRD experiments and with multi-slice image simulations for the corresponding NCSI contrast conditions used. The high precision achievable in such experiments is confirmed by a detailed quantitative analysis of the atom column positions at the incommensurate interfaces, proving a tetragonal distortion of the monochalcogenide sublattice. -- Research Highlights: → Quantitative aberration-corrected HRTEM analysis of atomic column positions in (PbS) 1.14 NbS 2 misfit layered compound reveals tetragonal distortion of the PbS subsystem. → Detailed comparison of multi-slice simulations with the experimental NCSI contrast condition imaging results lead to a high precision (better than 10 pm) for determining the positions of atoms. → Precision in gaining information of local structure at atomic scale is demonstrated, which may not be accessible by means of X-ray and neutron diffraction analysis.

  9. Effect of Promoter Concentration on CO2 Separation Using K2CO3 With Reactive Absorption Method in Reactor Packed Column

    Directory of Open Access Journals (Sweden)

    Monde Junety

    2018-01-01

    Full Text Available The presence of carbon dioxide (CO2 in the gas is not expected because CO2 can reduce heating value and CO2 is the major emission contributor into the atmosphere. Various separation technologies can be used to reduce CO2 content and improve quality of gas. Chemical or reactive absorption is most widely used because it provides higher removal rate. This paper will study the effect of the addition di ethanolamine (DEA concentration into aqueous 30wt.% potassium carbonate(K2CO3 with reactive absorption method in a reactor packed column at temperature from 40°C to 80°C, DEA concentration range of (1% - 3% and absorbent flow rate (0.5, 0.75 and 1 L. min1. Contacting the gas and absorbent are countercurrent flow in packed column with 1.5 m high and 50 mm in diameter. The absorption column was randomly packed with a packing material raschig rings 5 mm in diameter. The CO2 loading in the liquid samples was determined by titration. It is found that the best result of CO2 loading is 0.065594 mole/mole K2CO3 and CO2 removal 28%. The result show that the loading capacity (mole CO2/mole K2CO3 and CO2 removal increased with the increase of DEA concentration.

  10. Retrieve of atmospheric SO2 and O3 columns in the UV region using mobile DOAS

    International Nuclear Information System (INIS)

    Galicia, R.; La Rosa, J. de la; Stolik, S.

    2012-01-01

    We present the use of a passive DOAS system to retrieve SO2 and O3 columns emitted by industrial chimneys. It works with software built in LabVIEW and running with a PC linked to mini spectrometer and GPS. The system uses the sun light as light source, a telescope a fiber optic, a mini-spectrometer and a GPS. The spectrometer and the GPS are linked to a PC where the system is controlled and where all data are processed to retrieve the SO2 and O3 slant columns. (Author)

  11. Adiabatic packed column supercritical fluid chromatography using a dual-zone still-air column heater.

    Science.gov (United States)

    Helmueller, Shawn C; Poe, Donald P; Kaczmarski, Krzysztof

    2018-02-02

    An approach to conducting SFC separations under pseudo-adiabatic condition utilizing a dual-zone column heater is described. The heater allows for efficient separations at low pressures above the critical temperature by imposing a temperature profile along the column wall that closely matches that for isenthalpic expansion of the fluid inside the column. As a result, the efficiency loss associated with the formation of radial temperature gradients in this difficult region can be largely avoided in packed analytical scale columns. For elution of n-octadecylbenzene at 60 °C with 5% methanol modifier and a flow rate of 3 mL/min, a 250 × 4.6-mm column packed with 5-micron Kinetex C18 particles began to lose efficiency (8% decrease in the number of theoretical plates) at outlet pressures below 142 bar in a traditional forced air oven. The corresponding outlet pressure for onset of excess efficiency loss was decreased to 121 bar when the column was operated in a commercial HPLC column heater, and to 104 bar in the new dual-zone heater operated in adiabatic mode, with corresponding increases in the retention factor for n-octadecylbenzene from 2.9 to 6.8 and 14, respectively. This approach allows for increased retention and efficient separations of otherwise weakly retained analytes. Applications are described for rapid SFC separation of an alkylbenzene mixture using a pressure ramp, and isobaric separation of a cannabinoid mixture. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Column Liquid Chromatography.

    Science.gov (United States)

    Majors, Ronald E.; And Others

    1984-01-01

    Reviews literature covering developments of column liquid chromatography during 1982-83. Areas considered include: books and reviews; general theory; columns; instrumentation; detectors; automation and data handling; multidimensional chromatographic and column switching techniques; liquid-solid chromatography; normal bonded-phase, reversed-phase,…

  13. Ion chromatographic determination of fluoride and chloride in UO2 using microbore anion exchange columns

    International Nuclear Information System (INIS)

    Kelkar, Anoop; Meena, D.L.; Das, D.K.; Behere, P.G.; Mohd Afzal

    2015-01-01

    Chemical characterization of nuclear fuels is required to ensure that nuclear fuel meets the technical specifications of the fuel. Trace non- metallic impurities like Cl and F is important as they affect clad corrosion. Their effect is more severe in presence of moisture. Chlorine and Fluorine is routinely analysed by ion selective electrode or conventional ion chromatography after pyrohydrolyzing the sample in moist O 2 atmosphere at 950°. Both the technique generates large quantity of liquid waste. Generally 1 ml/min flow rate required for the separation of F - and Cl - in conventional ion-chromatographic separation of F - and Cl - on 4.6- 4.0 mm id analytical column. The waste produced per sample injection is ∼ 30-40 ml with suppressed conductivity detection in ion chromatography. There is a need to reduce this analytical waste in analyzing the radioactive samples for the determination of F - and Cl - . Waste generation could be effectively reduced by using microbore anion exchange analytical column. Present paper describe the use of Metrosep A Supp 16 - 100/2.0 column with Na 2 CO 3 +NaOH mobile phase for the determination of F - and Cl - in UO 2 samples using suppressed conductivity detection

  14. Chapter 2: Optical Properties of the Water Column

    Science.gov (United States)

    Kiefer, D. A.; Collins, D. J.

    1994-01-01

    In this chapter, and in chapter 29, the basic inter-relationship between the flux of radiant energy through the water column and the fixation of carbon by the phytoplankton in the ocean through processes of photosynthesis or primary production will be discussed.

  15. Ether lipids of planktonic archae in the marine water column

    NARCIS (Netherlands)

    Sinninghe Damsté, J.S.; Hoefs, M.J.L.; Schouten, S.; King, L.L.; Wakeham, S.G.; Leeuw, J.W. de

    1997-01-01

    Acyclic and cyclic biphytanes derived from the membrane ether lipids of archaea were found in water column particulate and sedimentary organic matter from several oxic and anoxic marine environments. Compound-specific isotope analyses of the carbon skeletons suggest that planktonic archaea utilize

  16. Bioremediation of a diesel fuel contaminated aquifer: simulation studies in laboratory aquifer columns

    Science.gov (United States)

    Hess, A.; Höhener, P.; Hunkeler, D.; Zeyer, J.

    1996-08-01

    The in situ bioremediation of aquifers contaminated with petroleum hydrocarbons is commonly based on the infiltration of groundwater supplemented with oxidants (e.g., O 2, NO 3-) and nutrients (e.g., NH 4+, PO 43-). These additions stimulate the microbial activity in the aquifer and several field studies describing the resulting processes have been published. However, due to the heterogeneity of the subsurface and due to the limited number of observation wells usually available, these field data do not offer a sufficient spatial and temporal resolution. In this study, flow-through columns of 47-cm length equipped with 17 sampling ports were filled with homogeneously contaminated aquifer material from a diesel fuel contaminated in situ bioremediation site. The columns were operated over 96 days at 12°C with artificial groundwater supplemented with O 2, NO 3- and PO 43-. Concentration profiles of O 2, NO 3-, NO 2-, dissolved inorganic and organic carbon (DIC and DOC, respectively), protein, microbial cells and total residual hydrocarbons were measured. Within the first 12 cm, corresponding to a mean groundwater residence time of < 3.6 h, a steep O 2 decrease from 4.6 to < 0.3 mg l -1, denitrification, a production of DIC and DOC, high microbial cell numbers and a high removal of hydrocarbons were observed. Within a distance of 24 to 40.5 cm from the infiltration, O 2 was below 0.1 mg l -1 and a denitrifying activity was found. In the presence and in the absence of O 2, n-alkanes were preferentially degraded compared to branched alkanes. The results demonstrate that: (1) infiltration of aerobic groundwater into columns filled with aquifer material contaminated with hydrocarbons leads to a rapid depletion of O 2; (2) O 2 and NO 3- can serve as oxidants for the mineralization of hydrocarbons; and (3) the modelling of redox processes in aquifers has to consider denitrifying activity in presence of O 2.

  17. Buckling of Nonprismatic Column on Varying Elastic Foundation with Arbitrary Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Ahmad A. Ghadban

    2017-01-01

    Full Text Available Buckling of nonprismatic single columns with arbitrary boundary conditions resting on a nonuniform elastic foundation may be considered as the most generalized treatment of the subject. The buckling differential equation for such columns is extremely difficult to solve analytically. Thus, the authors propose a numerical approach by discretizing the column into a finite number of segments. Each segment has constants E (modulus of elasticity, I (moment of inertia, and β (subgrade stiffness. Next, an exact analytical solution is derived for each prismatic segment resting on uniform elastic foundation. These segments are then assembled in a matrix from which the critical buckling load is obtained. The derived formulation accounts for different end boundary conditions. Validation is performed by benchmarking the present results against analytical solutions found in the literature, showing excellent agreement. After validation, more examples are solved to illustrate the power and flexibility of the proposed method. Overall, the proposed method provides reasonable results, and the examples solved demonstrate the versatility of the developed approach and some of its many possible applications.

  18. Mass transfer in liquid phase catalytic exchange column of trickle bed type

    International Nuclear Information System (INIS)

    Yamanishi, Toshihiko; Iwai, Yasunori; Okuno, Kenji

    1995-09-01

    The mechanism of mass transfer in a liquid phase catalytic exchange column was discussed for a trickle bed type. A new model has been proposed on the basis of this mass transfer mechanism; and several problems for the previous reported models were pointed out in the derivation of the model. An overall rate equation was first derived from the vapor-hydrogen exchange in the model. The mass transfer for the vapor-hydrogen exchange was decomposed to the following three steps: the mass transfer in a gas boundary layer on a catalyst particle; the mass transfer within the pores in the catalyst; and the chemical reaction on the surface of the catalyst. The water-vapor scrubbing process was considered as a series of the mass transfers in gas and liquid boundary layers on the wetted surfaces of the catalyst and packings or wall of the column. Significant subjects to be studied were proposed from the viewpoint of the validity of the model and the optimization of the column. (author)

  19. First Simultaneous Visualization of SO2 and NO2 Plume Dispersions using Imaging Differential Optical Absorption Spectroscopy

    International Nuclear Information System (INIS)

    Lee, Hanlim; Hong, Hyunkee; Han, Kyungsoo; Noh, Youngmin; Kwon, Soonchul

    2014-01-01

    Imaging Differential Optical Absorption Spectroscopy (Imaging-DOAS) has been utilized in recent years to provide slant column density (SCD) distributions of several trace gas species in the plume. The present study introduces a new method using Imaging-DOAS data to determine two-dimensional plume structure from the plume emissions of power plant in conditions of negligible aerosol effects on radiative transfer within the plume. We demonstrates for the first time that two-dimensional distributions of sulfur dioxide (SO 2 ) and nitrogen dioxide (NO 2 ) in power plant emissions can be determined simultaneously in terms of SCD distribution. The SO 2 SCD values generally decreased with increasing distance from the stack and with distance from the center of the plume. Meanwhile, high NO 2 SCD was observed at locations several hundred meters away from the first stack due to the ratio change of NO to NO 2 in NOx concentration, attributed to the NO oxidation by O 3 . The results of this study show the capability of the Imaging-DOAS technique as a tool to estimate plume dimensions in power plant emissions

  20. Heat Transfer Analysis for a Fixed CST Column

    International Nuclear Information System (INIS)

    Lee, S.Y.

    2004-01-01

    In support of a small column ion exchange (SCIX) process for the Savannah River Site waste processing program, a transient two-dimensional heat transfer model that includes the conduction process neglecting the convection cooling mechanism inside the crystalline silicotitanate (CST) column has been constructed and heat transfer calculations made for the present design configurations. For this situation, a no process flow condition through the column was assumed as one of the reference conditions for the simulation of a loss-of-flow accident. A series of the modeling calculations has been performed using a computational heat transfer approach. Results for the baseline model indicate that transit times to reach 130 degrees Celsius maximum temperature of the CST-salt solution column are about 96 hours when the 20-in CST column with 300 Ci/liter heat generation source and 25 degrees Celsius initial column temperature is cooled by natural convection of external air as a primary heat transfer mechanism. The modeling results for the 28-in column equipped with water jacket systems on the external wall surface of the column and water coolant pipe at the center of the CST column demonstrate that the column loaded with 300 Ci/liter heat source can be maintained non-boiling indefinitely. Sensitivity calculations for several alternate column sizes, heat loads of the packed column, engineered cooling systems, and various ambient conditions at the exterior wall of the column have been performed under the reference conditions of the CST-salt solution to assess the impact of those parameters on the peak temperatures of the packed column for a given transient time. The results indicate that a water-coolant pipe at the center of the CST column filled with salt solution is the most effective one among the potential design parameters related to the thermal energy dissipation of decay heat load. It is noted that the cooling mechanism at the wall boundary of the column has significant

  1. Understanding and diminishing the extra-column band broadening effects in supercritical fluid chromatography.

    Science.gov (United States)

    De Pauw, Ruben; Shoykhet Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

    2015-07-17

    Supercritical fluid chromatography, where a low-viscosity mobile phase such as carbon dioxide is used, proves to be an excellent technique for fast and efficient separations, especially when sub-2μm particles are used. However, to achieve high velocities when using these small particles, and in order to stay within the flow rate range of current SFC-instruments, narrow columns (e.g. 2.1mm ID) must be used. Unfortunately, state-of-the-art instrumentation is limiting the full separation power of these narrower columns due to significant extra-column band broadening effects. The present work identifies and quantifies the different contributions to extra-column band broadening in SFC such as the influence of the sample solvent, injection volume, extra-column volumes and detector cell volume/design. When matching the sample solvent to the mobile phase in terms of elution strength and polarity (e.g. using hexane/ethanol/isopropanol 85/10/5vol%) and lowering the injection volume to 0.4μL, the plate count can be increased from 7600 to 21,300 for a low-retaining compound (k'=2.3) on a 2.1mm×150mm column (packed with 1.8μm particles). The application of a water/acetonitrile mixture as sample solvent was also investigated. It was found that when the volumetric ratio of water/acetonitrile was optimized, only a slightly lower plate count was measured compared to the hexane-based solvent when minimizing injection and extra-column volume. This confirms earlier results that water/acetonitrile can be used if water-soluble samples are considered or when a less volatile solvent is preferred. Minimizing the ID of the connection capillaries from 250 to 65μm, however, gives no further improvement in obtained efficiency for early-eluting compounds when a standard system configuration with optimized sample solvent was used. When switching to a state-of-the-art detector design with reduced (dispersion) volume (1.7-0.6μL), an increase in plate count is observed (from 11,000 to 14

  2. Bubble column fermenter modeling: a comparison for pressure effects

    Energy Technology Data Exchange (ETDEWEB)

    Shioya, S; Dang, N D.P.; Dunn, I J

    1978-01-01

    Two models which describe the oxygen transfer, oxygen uptake, and axial mixing in a bubble column fermenter are described. Model I includes no pressure effects and can be solved analytically. Model II incorporates the influence of hydrostatic pressure on oxygen solubility and gas expansion and must be solved numerically. The liquid phase oxygen concentration profiles from both models are compared to ascertain for what parametric conditions and for what maximum column height Model I is valid. Results show that for many situations Model I can approximate the oxygen profiles in a 10 m column within 20%. As the transfer and uptake rates increase, the deviation of Model I can reach 80% for a 10 m column. 7 figures.

  3. Characterization of Schiff base derived from 2-hydroxo-1 ...

    African Journals Online (AJOL)

    MBI

    2014-03-04

    Mar 4, 2014 ... derived from 2, 2' bis(p-methoxylphenylamine) and salicylic ... containing Co(II), Ni(II), Cu(II) and Zn(II) synthesized from ..... pKa = 12.55. Ka = 2.81E-13 .... 20, no. 3, 297 – 300. Gaowen Y., Xiaping X. , Huan T. and Chenxue Z.

  4. Measurement of atmospheric CO2 column concentrations to cloud tops with a pulsed multi-wavelength airborne lidar

    Science.gov (United States)

    Mao, Jianping; Ramanathan, Anand; Abshire, James B.; Kawa, Stephan R.; Riris, Haris; Allan, Graham R.; Rodriguez, Michael; Hasselbrack, William E.; Sun, Xiaoli; Numata, Kenji; Chen, Jeff; Choi, Yonghoon; Yang, Mei Ying Melissa

    2018-01-01

    We have measured the column-averaged atmospheric CO2 mixing ratio to a variety of cloud tops by using an airborne pulsed multi-wavelength integrated-path differential absorption (IPDA) lidar. Airborne measurements were made at altitudes up to 13 km during the 2011, 2013 and 2014 NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) science campaigns flown in the United States West and Midwest and were compared to those from an in situ sensor. Analysis of the lidar backscatter profiles shows the average cloud top reflectance was ˜ 5 % for the CO2 measurement at 1572.335 nm except to cirrus clouds, which had lower reflectance. The energies for 1 µs wide laser pulses reflected from cloud tops were sufficient to allow clear identification of CO2 absorption line shape and then to allow retrievals of atmospheric column CO2 from the aircraft to cloud tops more than 90 % of the time. Retrievals from the CO2 measurements to cloud tops had minimal bias but larger standard deviations when compared to those made to the ground, depending on cloud top roughness and reflectance. The measurements show this new capability helps resolve CO2 horizontal and vertical gradients in the atmosphere. When used with nearby full-column measurements to ground, the CO2 measurements to cloud tops can be used to estimate the partial-column CO2 concentration below clouds, which should lead to better estimates of surface carbon sources and sinks. This additional capability of the range-resolved CO2 IPDA lidar technique provides a new benefit for studying the carbon cycle in future airborne and space-based CO2 missions.

  5. Measurement of Atmospheric CO2 Column Concentrations to Cloud Tops With a Pulsed Multi-Wavelength Airborne Lidar

    Science.gov (United States)

    Mao, Jianping; Ramanathan, Anand; Abshire, James B.; Kawa, Stephan R.; Riris, Haris; Allan, Graham R.; Rodriguez, Michael R.; Hasselbrack, William E.; Sun, Xiaoli; Numata, Kenji; hide

    2018-01-01

    We have measured the column-averaged atmospheric CO2 mixing ratio to a variety of cloud tops by using an airborne pulsed multi-wavelength integrated-path differential absorption (IPDA) lidar. Airborne measurements were made at altitudes up to 13 km during the 2011, 2013 and 2014 NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) science campaigns flown in the United States West and Midwest and were compared to those from an in situ sensor. Analysis of the lidar backscatter profiles shows the average cloud top reflectance was approx. 5% for the CO2 measurement at 1572.335 nm except to cirrus clouds, which had lower reflectance. The energies for 1 micro-s wide laser pulses reflected from cloud tops were sufficient to allow clear identification of CO2 absorption line shape and then to allow retrievals of atmospheric column CO2 from the aircraft to cloud tops more than 90% of the time. Retrievals from the CO2 measurements to cloud tops had minimal bias but larger standard deviations when compared to those made to the ground, depending on cloud top roughness and reflectance. The measurements show this new capability helps resolve CO2 horizontal and vertical gradients in the atmosphere. When used with nearby full-column measurements to ground, the CO2 measurements to cloud tops can be used to estimate the partial-column CO2 concentration below clouds, which should lead to better estimates of surface carbon sources and sinks. This additional capability of the range-resolved CO2 IPDA lidar technique provides a new benefit for studying the carbon cycle in future airborne and space-based CO2 missions.

  6. Mechanism of nucleation and growth of catalyst-free self-organized GaN columns by MOVPE

    Science.gov (United States)

    Wang, Xue; Li, Shunfeng; Fündling, Sönke; Wehmann, Hergo-H.; Strassburg, Martin; Lugauer, Hans-Jürgen; Steegmüller, Ulrich; Waag, Andreas

    2013-05-01

    The growth mechanism of catalyst-free self-organized GaN nuclei and three-dimensional columns on sapphire by metal organic vapour phase epitaxy (MOVPE) is investigated. Temperature- and time-dependent growth is performed. The growth behaviour can be characterized by two different kinetic regimes: mass-transport-limited growth and thermodynamically limited growth. The sum of activation energies for thermodynamic barrier of nucleation and for surface diffusion/mass-transport limitation, i.e. Whet +Ed, is 0.57 eV in the ‘low’-temperature region and 2.43 eV in the ‘high’-temperature region. GaN columns grown under the same conditions have very comparable height, which is not dependent on their diameter or the distance to other columns. Therefore, the growth rate is presumably limited by the incorporation rate on the top surface of columns. The height and diameter at the top of the GaN columns increase linearly with time and no height limit is observed. The GaN columns can reach more than 40 µm in height. Moreover, the investigated GaN columns are Ga-polar.

  7. Seasonal & Daily Amazon Column CO2 & CO Observations from Ground & Space Used to Evaluate Tropical Ecosystem Models

    Science.gov (United States)

    Dubey, M. K.; Parker, H. A.; Wennberg, P. O.; Wunch, D.; Jacobson, A. R.; Kawa, S. R.; Keppel-Aleks, G.; Basu, S.; O'Dell, C.; Frankenberg, C.; Michalak, A. M.; Baker, D. F.; Christofferson, B.; Restrepo-Coupe, N.; Saleska, S. R.; De Araujo, A. C.; Miller, J. B.

    2016-12-01

    The Amazon basin stores 150-200 PgC, exchanges 18 PgC with the atmosphere every year and has taken up 0.42-0.65 PgC/y over the past two decades. Despite its global significance, the response of the tropical carbon cycle to climate variability and change is ill constrained as evidenced by the large negative and positive feedbacks in future climate simulations. The complex interplay of radiation, water and ecosystem phenology remains unresolved in current tropical ecosystem models. We use high frequency regional scale TCCON observations of column CO2, CO and CH4 near Manaus, Brazil that began in October 2014 to understand the aforementioned interplay of processes in regulating biosphere-atmosphere exchange. We observe a robust daily column CO2 uptake of about 2 ppm (4 ppm to 0.5 ppm) over 8 hours and evaluate how it changes as we transition to the dry season. Back-trajectory calculations show that the daily CO2 uptake footprint is terrestrial and influenced by the heterogeneity of the Amazon rain forests. The column CO falls from above 120 ppb to below 80 ppb as we transition from the biomass burning to wet seasons. The daily mean column CO2 rises by 3 ppm from October through June. Removal of biomass burning, secular CO2 increase and variations from transport (by Carbon tracker simulations) implies an increase of 2.3 ppm results from tropical biospheric processes (respiration and photosynthesis). This is consistent with ground-based remote sensing and eddy flux observations that indicate that leaf development and demography drives the tropical carbon cycle in regions that are not water limited and is not considered in current models. We compare our observations with output from 7 CO2 inversion transport models with assimilated meteorology and find that while 5 models reproduce the CO2 seasonal cycle all of them under predict the daily drawdown of CO2 by a factor of 3. This indicates that the CO2 flux partitioning between photosynthesis and respiration is incorrect

  8. Distance and total column density to the periodic radio star LSI + 61 deg 303

    International Nuclear Information System (INIS)

    Frail, D.A.; Hjellming, R.M.

    1991-01-01

    New observations toward the periodic radio star LSI + 61 deg 303 in the lines of H I at 21 cm and CO-18 at 2.7 mm are reported. Using the kinematic method, H I observations are interpreted in terms of the two-armed spiral shock model of Roberts (1972) to derive a distance to LSI + 61 deg 303 of 2.0 + or - 0.2 kpc. The results clearly show the presence of the Perseus arm shock and locate LSI + 61 deg 303 between this shock and the more distant postshock gas. In addition, by using the H I and CO-18 data, the total neutral and molecular gas column density is derived along the line of sight toward LSI + 61 deg 303. 32 refs

  9. Influence of aerosols and surface reflectance on satellite NO2 retrieval: seasonal and spatial characteristics and implications for NOx emission constraints

    NARCIS (Netherlands)

    Lin, J.T.; Liu, M.Y.; Xin, J.Y.; Boersma, K.F.; Spurr, R.; Zhang, Q.; Martin, R.

    2015-01-01

    Satellite retrievals of vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) normally do not explicitly account for aerosol optical effects and surface reflectance anisotropy that vary with space and time. Here, we conduct an improved retrieval of NO2 VCDs over China, called the

  10. Properties of local equations for a separation column

    International Nuclear Information System (INIS)

    Hodor, I.

    1992-01-01

    An overall theory of column separation is developed. A general expression for fully-developed concentration fields is found. For close-separation processes, a simple method to derive the theoretical plate height and the stage efficiency from local equations are given. Application of separation-of-variables to linearized systems is discussed and a partial range completeness of the eigenfunctions is found. (author)

  11. Mitigation of Oil in Water Column: Concept Development

    Science.gov (United States)

    2016-06-01

    subsea pipeline leaks , or the leaking of oil from tanks after a damaged vessel has sunk to the bottom. Oil arriving at the surface of the water may...i Classification | CG-926 RDC | author | audience | month year Mitigation of Oil in Water Column: Concept Development Distribution...Center. June 2016 Report No. CG-D-03-16 Mitigation of Oil in Water Column: Concept Development ii UNCLAS//Public | CG-926 RDC

  12. A Novel Triple-Pulsed 2-micrometer Lidar for Simultaneous and Independent CO2 and H2O Column Measurement

    Science.gov (United States)

    Yu, Jirong; Singh, Upendra; Petros, Mulugeta; Refaat, Tamer

    2015-01-01

    The study of global warming needs precisely and accurately measuring greenhouse gases concentrations in the atmosphere. CO2 and H2O are important greenhouse gases that significantly contribute to the carbon cycle and global radiation budget on Earth. NRC Decadal Survey recommends a mission for Active Sensing of Carbon Dioxide (CO2) over Nights, Days and Seasons (ASCENDS). 2 micron laser is a viable IPDA transmitter to measure CO2 and H2O column density from space. The objective is to demonstrate a first airborne direct detection 2 micron IPDA lidar for CO2 and H2O measurements.

  13. Determination of the vildagliptin intermediate enantiomer by chiralce-columns

    Directory of Open Access Journals (Sweden)

    Weina LI

    2017-06-01

    Full Text Available In order to establish a NP-HPLC method for the determination of enantiomer in vildagliptin intermediate, the determination is carried out on the column of ChiralpakAD-H(250 mm×4.6 mm, 5 μm, with the mobile phase of n-hexane, ethanol and methanol(volume ratio of 65∶25∶10)at flow rate of 0.8 mL/min. The sample volume is 10 μL, the wavelength is 210 nm and the column temperature is 35 ℃. The result shows that the vildagliptin intermediate and its enantiomer could be well separated and detected effectively; blank solvent doesn't interfere with the enantiomer assaying; the detection limit is 27 ng/mL and the quantification limit is 81 ng/mL; in repetitive test, the RSD of enantiomer assaying of samples are no more than 2.0%; in stability test, the RSD are no more than 2.0% in 12 h; the vildagliptin intermediate and its enantiomer could be well separated in the test of durability with all RSDs below 2.0%. The method is simple, reliable, accurate and durable, and can be used for determination of enantiomer in vildagliptin intermediate.

  14. Removal of geosmin and 2-methylisoborneol during managed aquifer recharge: Batch and column studies

    KAUST Repository

    Maeng, Sungkyu; Abel, Chol D T; Sharma, Saroj K.; Park, Nosuk; Amy, Gary L.

    2012-01-01

    Managed aquifer recharge is a robust barrier in the multi-barrier approach to supply safe drinking water. The removal performance of gesomin and 2-methylisoborneol through managed aquifer recharge was investigated using batch and column experiments

  15. Sheath and arc-column voltages in high-pressure arc discharges

    International Nuclear Information System (INIS)

    Benilov, M S; Benilova, L G; Li Heping; Wu Guiqing

    2012-01-01

    Electrical characteristics of a 1 cm-long free-burning atmospheric-pressure argon arc are calculated by means of a model taking into account the existence of a near-cathode space-charge sheath and the discrepancy between the electron and heavy-particle temperatures in the arc column. The computed arc voltage exhibits a variation with the arc current I similar to the one revealed by the experiment and exceeds experimental values by no more than approximately 2 V in the current range 20-175 A. The sheath contributes about two-thirds or more of the arc voltage. The LTE model predicts a different variation of the arc voltage with I and underestimates the experimental values appreciably for low currents but by no more than approximately 2 V for I ≳ 120 A. However, the latter can hardly be considered as a proof of unimportance of the space-charge sheath at high currents: the LTE model overestimates both the resistance of the bulk of the arc column and the resistance of the part of the column that is adjacent to the cathode, and this overestimation to a certain extent compensates for the neglect of the voltage drop in the sheath. Furthermore, if the latter resistance were evaluated in the framework of the LTE model in an accurate way, then the overestimation would be still much stronger and the obtained voltage would significantly exceed those observed in the experiment.

  16. Monolithic poly(1,2-bis(p-vinylphenyl)ethane) capillary columns for simultaneous separation of low- and high-molecular-weight compounds.

    Science.gov (United States)

    Greiderer, Andreas; Ligon, S Clark; Huck, Christian W; Bonn, Günther K

    2009-08-01

    Monolithic poly(1,2-bis(p-vinylphenyl)ethane (BVPE)) capillary columns were prepared by thermally initiated free radical polymerisation of 1,2-bis(p-vinylphenyl)ethane in the presence of inert diluents (porogens) and alpha,alpha'-azoisobutyronitrile (AIBN) as initiator. Polymerisations were accomplished in 200 microm ID fused silica capillaries at 65 degrees C and for 60 min. Mercury intrusion porosimetry measurements of the polymeric RP support showed a broad bimodal pore-size-distribution of mesopores and small macropores in the range of 5-400 nm and flow-channels in the mum range. N(2)-adsorption (BET) analysis resulted in a tremendous enhancement of surface area (101 m(2)/g) of BVPE stationary phases compared to typical organic monoliths (approximately 20 m(2)/g), indicating the presence of a considerable amount of mesopores. Consequently, the adequate proportion of both meso- and (small) macropores allowed the rapid and high-resolution separation of low-molecular-weight compounds as well as biomolecules on the same monolithic support. At the same time, the high fraction of flow-channels provided enhanced column permeability. The chromatographic performance of poly(1,2-bis(p-vinylphenyl)ethane) capillary columns for the separation of biomolecules (proteins, oligonucleotides) and small molecules (alkyl benzenes, phenols, phenons) are demonstrated in this article. Additionally, pressure drop versus flow rate measurements of novel poly(1,2-bis(p-vinylphenyl)ethane) capillary columns confirmed high mechanical robustness, low swelling in organic solvents and high permeability. Due to the simplicity of monolith fabrication, comprehensive studies of the retention and separation behaviour of monolithic BVPE columns resulted in high run-to-run and batch-to-batch reproducibilities. All these attributes prove the excellent applicability of monolithic poly(1,2-bis(p-vinylphenyl)ethane) capillary columns for micro-HPLC towards a huge range of analytes of different

  17. PRTR ion exchange vault column sampling

    International Nuclear Information System (INIS)

    Cornwell, B.C.

    1995-01-01

    This report documents ion exchange column sampling and Non Destructive Assay (NDA) results from activities in 1994, for the Plutonium Recycle Test Reactor (PRTR) ion exchange vault. The objective was to obtain sufficient information to prepare disposal documentation for the ion exchange columns found in the PRTR Ion exchange vault. This activity also allowed for the monitoring of the liquid level in the lower vault. The sampling activity contained five separate activities: (1) Sampling an ion exchange column and analyzing the ion exchange media for purpose of waste disposal; (2) Gamma and neutron NDA testing on ion exchange columns located in the upper vault; (3) Lower vault liquid level measurement; (4) Radiological survey of the upper vault; and (5) Secure the vault pending waste disposal

  18. Evaluation of pharmaceuticals removal by sewage sludge-derived adsorbents with rapid small-scale column tests

    Science.gov (United States)

    Zhang, P.; Ding, R.; Wallace, R.; Bandosz, T.

    2015-12-01

    New composite adsorbents were developed by pyrolyzing sewage sludge and fish waste (75:25 or 90:10 dry mass ratio) at 650 oC and 950 oC. Batch adsorption experiments demonstrated that the composite adsorbents were able to adsorb a wide range of organic contaminants (volatile organic compounds, pharmaceuticals and endocrine disrupting compounds (EDCs), and nitrosamine disinfection byproducts) with high capacities. Here we further examine the performance of the adsorbents for the simultaneous removal of 8 pharmaceuticals and EDCs with rapid small-scale column tests (RSSCT). Results show that the order of breakthrough in RSSCT is in general consistent with the affinity determined via batch tests. As expected, the maximum amount of adsorption for each compound obtained from RSSCT is identical to or less than that obtained from batch tests (with only one exception), due to adsorption kinetics. However, despite the very different input concentration (1 mg/L vs. 100 mg/L) and contact time (2 min empty bed contact time vs. 16 hour equilibrium time) used in RSSCT and batch tests, the maximum amount of pharmaceuticals and EDCs adsorbed under RSSCT is still about one half of that under equilibrium batch tests, validating the approach of using batch tests with much higher input concentrations to determine adsorption capacities. Results of a pilot-scale column test in a drinking water treatment plant for pharmaceuticals removal will also be presented.

  19. COLUMN2 - A computer program for simulating migration

    International Nuclear Information System (INIS)

    Nielsen, O.J.; Bo, P.; Carlsen, L.

    1985-10-01

    COLUMN2 is a 1D FORTRAN77 computer program designed for studies of the effects of various physicochemical processes on migration. It solves the solute transport equation and cant take into account dispersion, sorption, ion exchange, first and second order homogeneous chemical reactions. Spacial variations of input pulses and retention factors are possible. The method of solution is based on a finite difference discretion followed by the application of the method of characteristics and two separate grid systems. This report explains the mathematical and numerical methods used, describes the necessary input, contains a number of test examples, provides a listing of the program and explains how to acquire the program, adapt it to other computers and run it. This report serves as a manual for the program. (author)

  20. Measurement of atmospheric CO2 column concentrations to cloud tops with a pulsed multi-wavelength airborne lidar

    Directory of Open Access Journals (Sweden)

    J. Mao

    2018-01-01

    Full Text Available We have measured the column-averaged atmospheric CO2 mixing ratio to a variety of cloud tops by using an airborne pulsed multi-wavelength integrated-path differential absorption (IPDA lidar. Airborne measurements were made at altitudes up to 13 km during the 2011, 2013 and 2014 NASA Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS science campaigns flown in the United States West and Midwest and were compared to those from an in situ sensor. Analysis of the lidar backscatter profiles shows the average cloud top reflectance was ∼ 5 % for the CO2 measurement at 1572.335 nm except to cirrus clouds, which had lower reflectance. The energies for 1 µs wide laser pulses reflected from cloud tops were sufficient to allow clear identification of CO2 absorption line shape and then to allow retrievals of atmospheric column CO2 from the aircraft to cloud tops more than 90 % of the time. Retrievals from the CO2 measurements to cloud tops had minimal bias but larger standard deviations when compared to those made to the ground, depending on cloud top roughness and reflectance. The measurements show this new capability helps resolve CO2 horizontal and vertical gradients in the atmosphere. When used with nearby full-column measurements to ground, the CO2 measurements to cloud tops can be used to estimate the partial-column CO2 concentration below clouds, which should lead to better estimates of surface carbon sources and sinks. This additional capability of the range-resolved CO2 IPDA lidar technique provides a new benefit for studying the carbon cycle in future airborne and space-based CO2 missions.

  1. SLIP VELOCITY IN PULSED DISC AND DOUGHNUT EXTRACTION COLUMN

    Directory of Open Access Journals (Sweden)

    Mohammad Outokesh

    2011-09-01

    Full Text Available In the present work, slip velocity has been measured in a 76 mm diameter pulsed disc and doughnut extraction column for four different liquid-liquid systems. The effects of operating variables including pulsation intensity and dispersed and continuous phase flow rates on slip velocity have been investigated. The existence of three different operational regimes, namely mixersettler, transition, and emulsion regimes, was observed when the energy input was changed. Empirical correlations are derived for prediction of the slip velocity in terms of operating variables, physical properties of the liquid systems, and column geometry for different regimes. Good agreement between prediction and experiments was found for all operating conditions that were investigated.

  2. Post wall fixation by lag screw only in associated both column fractures with posterior wall involvement.

    Science.gov (United States)

    Wang, Hu; Utku, Kandemir; Zhuang, Yan; Zhang, Kun; Fu, Ya-Hui; Wei, Xing; Wang, Peng-Fei; Cong, Yu-Xuan; Lei, Jin-Lai; Zhang, Bin-Fei

    2017-07-01

    To evaluate the quality of reduction, clinical outcomes and complications of associated both column acetabular fractures with posterior wall involvement that are treated through single ilioinguinal approach and fixation of posterior wall by lag screws only. We conducted a retrospective review involving ninety-nine consecutive patients with associated both column fractures of acetabulum treated through single ilioinguinal approach. Patients were divided into two groups. The first group consisted of 35 patients presented with both column fractures with posterior wall involvement that fixation performed with lag screws. This group was compared to a second group of 64 patients with both column fractures without posterior wall involvement. The quality of reduction was assessed using criteria described by Matta. The size of posterior wall fragment was measured. Functional outcome was evaluated using Modified Postel Merle D'Aubigne score. Radiographs at the latest follow up were analyzed for arthritis (Kellgren-Lawrence classification), and femoral head avascular necrosis (Ficat/Arlet classification). The study showed no significant differences in all preoperative variables (P>0.05). While intraoperative blood loss and operative time in group 1 were increased compared to group 2, the difference was not statistically significant (P>0.05). The height, relative depth and peripheral length of posterior wall respectively were 27.8±2.5mm (range: 24-35mm), 71.5±5.4% (range: 65-88%), 23.0±2.3mm (range: 17-28mm). The mean posterior wall fracture displacement is 5.0±3.2mm (range: 0-11mm). There was no difference regarding the quality of reduction between the two groups (P>0.05). The excellent to good clinical outcome was around 71.4% in the group 1 versus 73.4% in the group 2 at the final follow-up, this difference was not statistically significant (P>0.05). There was no difference in rate of complications between the two groups (P>0.05). Lag screws fixation of posterior wall

  3. A Modelling Framework for Conventional and Heat Integrated Distillation Columns

    DEFF Research Database (Denmark)

    Bisgaard, Thomas; Huusom, Jakob Kjøbsted; Abildskov, Jens

    2013-01-01

    of hydrocarbons such as separations of equimolar mixtures of benzene/toluene or propane/propene described by simple models, a generic, modular, model framework is presented in this work. At present, the framework is able to describe a conventional distillation column, a mechanical vapor recompression column......Diabatic operation of distillation columns can lead to signicant reductions in energy utilization and operation cost compared to conventional (adiabatic) distillation columns, at an expense of an increased complexity of design and operation. The earliest diabatic distillation conguration dates back...... to the late 70s, and various dierent congurations have appeared since. However, at present, no full-scale diabatic distillation columns are currently operating in the industry. Current studies related to alternative distillation congurations report very dierent gures for potential energy savings which...

  4. Evaluating a Space-Based Indicator of Surface Ozone-NO x -VOC Sensitivity Over Midlatitude Source Regions and Application to Decadal Trends.

    Science.gov (United States)

    Jin, Xiaomeng; Fiore, Arlene M; Murray, Lee T; Valin, Lukas C; Lamsal, Lok N; Duncan, Bryan; Boersma, K Folkert; De Smedt, Isabelle; Abad, Gonzalo Gonzalez; Chance, Kelly; Tonnesen, Gail S

    2017-10-16

    Determining effective strategies for mitigating surface ozone (O 3 ) pollution requires knowledge of the relative ambient concentrations of its precursors, NO x , and VOCs. The space-based tropospheric column ratio of formaldehyde to NO 2 (FNR) has been used as an indicator to identify NO x -limited versus NO x -saturated O 3 formation regimes. Quantitative use of this indicator ratio is subject to three major uncertainties: (1) the split between NO x -limited and NO x -saturated conditions may shift in space and time, (2) the ratio of the vertically integrated column may not represent the near-surface environment, and (3) satellite products contain errors. We use the GEOS-Chem global chemical transport model to evaluate the quantitative utility of FNR observed from the Ozone Monitoring Instrument over three northern midlatitude source regions. We find that FNR in the model surface layer is a robust predictor of the simulated near-surface O 3 production regime. Extending this surface-based predictor to a column-based FNR requires accounting for differences in the HCHO and NO 2 vertical profiles. We compare four combinations of two OMI HCHO and NO 2 retrievals with modeled FNR. The spatial and temporal correlations between the modeled and satellite-derived FNR vary with the choice of NO 2 product, while the mean offset depends on the choice of HCHO product. Space-based FNR indicates that the spring transition to NO x -limited regimes has shifted at least a month earlier over major cities (e.g., New York, London, and Seoul) between 2005 and 2015. This increase in NO x sensitivity implies that NO x emission controls will improve O 3 air quality more now than it would have a decade ago.

  5. Reductions of NO2 detected from space during the 2008 Beijing Olympic Games

    Science.gov (United States)

    Mijling, B.; van der A, R. J.; Boersma, K. F.; Van Roozendael, M.; De Smedt, I.; Kelder, H. M.

    2009-07-01

    During the 2008 Olympic and Paralympic Games in Beijing (from 8 August to 17 September), local authorities enforced strong measures to reduce air pollution during the events. To evaluate the direct effect of these measures, we use the tropospheric NO2 column observations from the satellite instruments GOME-2 and OMI. We interpret these data against simulations from the regional chemistry transport model CHIMERE, based on a 2006 emission inventory, and find a reduction of NO2 concentrations of approximately 60% above Beijing during the Olympic period. The air quality measures were especially effective in the Beijing area, but also noticeable in surrounding cities of Tianjin (30% reduction) and Shijiazhuang (20% reduction).

  6. Collapse of tall granular columns in fluid

    Science.gov (United States)

    Kumar, Krishna; Soga, Kenichi; Delenne, Jean-Yves

    2017-06-01

    Avalanches, landslides, and debris flows are geophysical hazards, which involve rapid mass movement of granular solids, water, and air as a multi-phase system. In order to describe the mechanism of immersed granular flows, it is important to consider both the dynamics of the solid phase and the role of the ambient fluid. In the present study, the collapse of a granular column in fluid is studied using 2D LBM - DEM. The flow kinematics are compared with the dry and buoyant granular collapse to understand the influence of hydrodynamic forces and lubrication on the run-out. In the case of tall columns, the amount of material destabilised above the failure plane is larger than that of short columns. Therefore, the surface area of the mobilised mass that interacts with the surrounding fluid in tall columns is significantly higher than the short columns. This increase in the area of soil - fluid interaction results in an increase in the formation of turbulent vortices thereby altering the deposit morphology. It is observed that the vortices result in the formation of heaps that significantly affects the distribution of mass in the flow. In order to understand the behaviour of tall columns, the run-out behaviour of a dense granular column with an initial aspect ratio of 6 is studied. The collapse behaviour is analysed for different slope angles: 0°, 2.5°, 5° and 7.5°.

  7. Second dimension column ensemble pressure tuning in comprehensive two-dimensional gas chromatography.

    Science.gov (United States)

    Sharif, Khan M; Kulsing, Chadin; Junior, Ademario I da Silva; Marriott, Philip J

    2018-02-09

    A pressure tunable (PT) coupled column ensemble has been implemented for the second dimension ( 2 D) separation in comprehensive two dimensional gas chromatography (GC×PTGC). This process requires two columns to be connected by a pressure junction, as a replacement for a single narrow bore, short column in 2 D. Various 2 D 1 and 2 D 2 columns may be selected to provide complementary selectivity (polarity) compared to the 1 D column. The tunable residence time arising from differential pressure drop in each 2 D column results in a tunable fractional contribution of each column in the 2 D separation. A sample mixture comprising different chemical classes, including alkanes and alcohols, is used to identify the feasibility and extent of selectivity tuning possible in GC×PTGC. The column length is also varied due to the imposed challenge of wraparound in the PT coupled column system as pressures are adjusted in the 2 D separation. Different experimental parameters, stationary phase materials and column lengths have been applied to investigate and understand the separation behaviour of the 2 D PT coupled column GC×GC system. Results are discussed considering analyte retention time, peak width, linear velocity and the contribution of each 2 D column. A specific and unexpected example of GC×GC separation was demonstrated where the peak positions of polar and apolar compounds could almost swap their 2 D retention position by application of PT. Kerosene was analysed as an example of complex sample analysis by GC×PTGC system. This process is shown to be a practical approach for altering different stationary phase selectivities in a single 2 D arrangement in GC×GC. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Comparative evaluation of post-column free radical scavenging and ferric reducing antioxidant power assays for screening of antioxidants in strawberries.

    Science.gov (United States)

    Raudonis, Raimondas; Raudone, Lina; Jakstas, Valdas; Janulis, Valdimaras

    2012-04-13

    ABTS and FRAP post-column techniques evaluate the antioxidant characteristics of HPLC separated compounds with specific reagents. ABTS characterize their ability to scavenge free radicals by electron-donating antioxidants, resulting in the absorbance decrease of the chromophoric radical. FRAP - is based on the reduction of Fe(III)-tripyridyltriazine complex to Fe(II)-tripyridyltriazine at low pH by electron-donating antioxidants, resulting in an absorbance increase. Both post-column assays were evaluated and compared according to the following validation parameters: specificity, precision, limit of detection (LoD), limit of quantitation (LoQ) and linearity. ABTS and FRAP post-column assays were specific, repeatable and sensitive and thus can be used for the evaluation of antioxidant active compounds. Antioxidant active compounds were quantified according to TEAC for each assay and ABTS/FRAP ratio was derived. No previous records of antioxidative activity of leaves and fruits of strawberries (Fragaria viridis, Fragaria moschata) research have been found. The research results confirm the reliability of ABTS and FRAP post-column assays for screening of antioxidants in complex mixtures and the determination of radical scavenging and ferric reducing ability by their TEAC values. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. The comparison of physical properties derived from gas and dust in a massive star-forming region

    Energy Technology Data Exchange (ETDEWEB)

    Battersby, Cara; Bally, John; Ginsburg, Adam; Darling, Jeremy [Center for Astrophysics and Space Astronomy, University of Colorado, UCB 389, Boulder, CO 80309 (United States); Dunham, Miranda [Department of Astronomy, Yale University, New Haven, CT 06520 (United States); Longmore, Steve [Astrophysics Research Institute, Liverpool John Moores University, Twelve Quays House, Egerton Wharf, Birkenhead CH41 1LD (United Kingdom)

    2014-05-10

    We explore the relationship between gas and dust in a massive star-forming region by comparing the physical properties derived from each. We compare the temperatures and column densities in a massive star-forming Infrared Dark Cloud (G32.02+0.05), which shows a range of evolutionary states, from quiescent to active. The gas properties were derived using radiative transfer modeling of the (1,1), (2,2), and (4,4) transitions of NH{sub 3} on the Karl G. Jansky Very Large Array, while the dust temperatures and column densities were calculated using cirrus-subtracted, modified blackbody fits to Herschel data. We compare the derived column densities to calculate an NH{sub 3} abundance, χ{sub NH{sub 3}} = 4.6 × 10{sup –8}. In the coldest star-forming region, we find that the measured dust temperatures are lower than the measured gas temperatures (mean and standard deviations T {sub dust,} {sub avg} ∼ 11.6 ± 0.2 K versus T {sub gas,} {sub avg} ∼ 15.2 ± 1.5 K), which may indicate that the gas and dust are not well-coupled in the youngest regions (∼0.5 Myr) or that these observations probe a regime where the dust and/or gas temperature measurements are unreliable. Finally, we calculate millimeter fluxes based on the temperatures and column densities derived from NH{sub 3}, which suggest that millimeter dust continuum observations of massive star-forming regions, such as the Bolocam Galactic Plane Survey or ATLASGAL, can probe hot cores, cold cores, and the dense gas lanes from which they form, and are generally not dominated by the hottest core.

  10. The comparison of physical properties derived from gas and dust in a massive star-forming region

    International Nuclear Information System (INIS)

    Battersby, Cara; Bally, John; Ginsburg, Adam; Darling, Jeremy; Dunham, Miranda; Longmore, Steve

    2014-01-01

    We explore the relationship between gas and dust in a massive star-forming region by comparing the physical properties derived from each. We compare the temperatures and column densities in a massive star-forming Infrared Dark Cloud (G32.02+0.05), which shows a range of evolutionary states, from quiescent to active. The gas properties were derived using radiative transfer modeling of the (1,1), (2,2), and (4,4) transitions of NH 3 on the Karl G. Jansky Very Large Array, while the dust temperatures and column densities were calculated using cirrus-subtracted, modified blackbody fits to Herschel data. We compare the derived column densities to calculate an NH 3 abundance, χ NH 3 = 4.6 × 10 –8 . In the coldest star-forming region, we find that the measured dust temperatures are lower than the measured gas temperatures (mean and standard deviations T dust, avg ∼ 11.6 ± 0.2 K versus T gas, avg ∼ 15.2 ± 1.5 K), which may indicate that the gas and dust are not well-coupled in the youngest regions (∼0.5 Myr) or that these observations probe a regime where the dust and/or gas temperature measurements are unreliable. Finally, we calculate millimeter fluxes based on the temperatures and column densities derived from NH 3 , which suggest that millimeter dust continuum observations of massive star-forming regions, such as the Bolocam Galactic Plane Survey or ATLASGAL, can probe hot cores, cold cores, and the dense gas lanes from which they form, and are generally not dominated by the hottest core.

  11. Column-Oriented Database Systems (Tutorial)

    NARCIS (Netherlands)

    D. Abadi; P.A. Boncz (Peter); S. Harizopoulos

    2009-01-01

    textabstractColumn-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as

  12. Experimental Evaluation of Beam to Diamond Box Column Connection with Through Plate in Moment Frames

    International Nuclear Information System (INIS)

    Keshavarzi, Farhad; Torabian, Shahabeddin; Imanpour, Ali; Mirghaderi, Rasoul

    2008-01-01

    Moment resisting frames with built up section have very enhanced features due to high bending stiffness and strength characteristics in two principal axes and access to column faces for beam to column easy connections. But due to proper transfer of beam stresses to column faces there were always some specific controvertibly issues that how to make the load transfer through and in plane manner in order to mobilize the forces in column faces. Using diamond column instead of box column provide possibility to mobilize the load transfer mechanism in column faces. This section as a column has considerable benefit such as high plastic to elastic section modulus ratio which is an effective factor for force controlled components. Typical connection has no chance to be applied with diamond column.This paper elucidates the seismic behavior of through-plates moment connections to diamond box columns for use in steel moment resisting frames. This connection has a lot of economical benefits such as no need to horizontal continuity plates and satisfying the weak beam--strong column criteria in the connection region. They might serve as panel zone plates as well. According to high shear demand in panel zone of beam to column joint one should use the doublers plates in order to decrease the shear strength demand in this sensitive part of structure but these plates have no possibility to mobilize the load transfer mechanism in column web and transfer them to column flanges. In this type of connection, column faces have effective role in order to decrease the demands on through plate and they are impressive factors for improving the performance of the connection.Experimental analysis was conducted to elucidate the seismic behavior of this connection. The results of Experimental analysis established the effectiveness of the through plate in mitigating local stress concentrations and forming the plastic hinge zone in the beam away from the beam to column interface. The moment

  13. Assessing the Suitability and Limitations of Satellite-based Measurements for Estimating CO, CO2, NO2 and O3 Concentrations over the Niger Delta

    Science.gov (United States)

    Fagbeja, M. A.; Hill, J. L.; Chatterton, T. J.; Longhurst, J. W.; Akinyede, J. O.

    2011-12-01

    Space-based satellite sensor technology may provide important tools in the study and assessment of national, regional and local air pollution. However, the application of optical satellite sensor observation of atmospheric trace gases, including those considered to be 'air pollutants', within the lower latitudes is limited due to prevailing climatic conditions. The lack of appropriate air pollution ground monitoring stations within the tropical belt reduces the ability to verify and calibrate space-based measurements. This paper considers the suitability of satellite remotely sensed data in estimating concentrations of atmospheric trace gases in view of the prevailing climate over the Niger Delta region. The methodological approach involved identifying suitable satellite data products and using the ArcGIS Geostatistical Analyst kriging interpolation technique to generate surface concentrations from satellite column measurements. The observed results are considered in the context of the climate of the study area. Using data from January 2001 to December 2005, an assessment of the suitability of satellite sensor data to interpolate column concentrations of trace gases over the Niger Delta has been undertaken and indicates varying degrees of reliability. The level of reliability of the interpolated surfaces is predicated on the number and spatial distributions of column measurements. Accounting for the two climatic seasons in the region, the interpolation of total column concentrations of CO and CO2 from SCIAMACHY produced both reliable and unreliable results over inland parts of the region during the dry season, while mainly unreliable results are observed over the coastal parts especially during the rainy season due to inadequate column measurements. The interpolation of tropospheric measurements of NO2 and O3 from GOME and OMI respectively produced reliable results all year. This is thought to be due to the spatial distribution of available column measurements

  14. Competitive adsorption and selectivity sequence of heavy metals by chicken bone-derived biochar: Batch and column experiment.

    Science.gov (United States)

    Park, Jong-Hwan; Cho, Ju-Sik; Ok, Yong Sik; Kim, Seong-Heon; Kang, Se-Won; Choi, Ik-Won; Heo, Jong-Soo; DeLaune, Ronald D; Seo, Dong-Cheol

    2015-01-01

    The objective of this research was to evaluate adsorption of heavy metals in single- and ternary-metal forms onto chicken bone biochar (CBB). Competitive sorption of heavy metals by CBB has never been reported previously. The maximum adsorption capacities of metals by CBB were in the order of Cu (130 mg g(-1)) > Cd (109 mg g(-1)) > Zn (93 mg g(-1)) in the single-metal adsorption isotherm and Cu (108 mg g(-1)) > Cd (54 mg g(-1)) ≥ Zn (44 mg g(-1)) in the ternary-metal adsorption isotherm. Cu was the most retained cation, whereas Zn could be easily exchanged and substituted by Cu. Batch experimental data best fit the Langmuir model rather than the Freundlich isotherms. In the column experiments, the total adsorbed amounts of the metals were in the following order of Cu (210 mg g(-1)) > Cd (192 mg g(-1)) > Zn (178) in single-metal conditions, and Cu (156) > Cd (123) > Zn (92) in ternary-metal conditions. Results from both the batch and column experiments indicate that competitive adsorption among metals increases the mobility of these metals. Especially, Zn in single-metal conditions lost it adsorption capacity most significantly. Based on the 3D simulation graphs of heavy metals, adsorption patterns under single adsorption condition were different than under competitive adsorption condition. Results from both the batch and column experiments show that competitive adsorption among metals increases the mobility of these metals. The maximum metal adsorption capacity of the metals in the column experiments was higher than that in the batch experiment indicating other metal retention mechanisms rather than adsorption may be involved. Therefore, both column and batch experiments are needed for estimating retention capacities and removal efficiencies of metals in CBB.

  15. Fabrication of a micrometer Ni–Cu alloy column coupled with a Cu micro-column for thermal measurement

    International Nuclear Information System (INIS)

    Lin, J C; Chang, T K; Yang, J H; Jeng, J H; Lee, D L; Jiang, S B

    2009-01-01

    Micrometer Ni–Cu alloy columns have been fabricated by the micro-anode-guided electroplating (MAGE) process in the citrate bath. The surface morphology and chemical composition of the micro-columns were determined by copper concentration in the bath and by the electrical bias of MAGE. When fabricated in a bath of dilute copper (i.e. 4 mM) at lower voltages (e.g. 3.8 and 4.0 V), the alloy micro-columns revealed uniform diameter and smooth appearance. The alloy composition demonstrated an increase in the wt% ratio of Ni/Cu from 75/25, 80/20, 83/17 to 87/13 with increasing electrical bias from 3.8, 4.0, 4.2 to 4.4 V. However, it decreases from 75/25, 57/43 to 47/53 with increasing copper concentration from 4, 8 to 12 mM in the bath. Citrate plays a role in forming complexes with nickel and copper at similar reduction potentials, thus reducing simultaneously to Ni–Cu alloy. The mechanism for fabricating alloy micro-columns could be delineated on the basis of cathodic polarization of the complexes. A couple of micro-columns were fabricated using MAGE in constructing a pure copper micro-column on the top of a Ni/Cu (at 47/53) alloy micro-column. This micro-thermocouple provides a satisfactory measurement with good sensitivity and precision

  16. OMI/Aura Nitrogen Dioxide (NO2) Total and Tropospheric Column 1-orbit L2 Swath 13x24 km V003

    Data.gov (United States)

    National Aeronautics and Space Administration — The second release of collection 3 OMI/Aura Level-2 NO2 data product OMNO2 is now available (http://disc.gsfc.nasa.gov/Aura/OMI/omno2_v003.shtml ) to public and...

  17. Preparation and evaluation of poly(alkyl methacrylate-co-methacrylic acid-co-ethylene dimethacrylate) monolithic columns for separating polar small molecules by capillary liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shu-Ling; Wu, Yu-Ru; Lin, Tzuen-Yeuan; Fuh, Ming-Ren, E-mail: msfuh@scu.edu.tw

    2015-04-29

    Highlights: • Methacrylic acid (MAA) was used to increase hydrophilicity of polymeric monoliths. • Fast separation of phenol derivatives was achieved in 5 min using MAA-incorporated column. • Separations of aflatoxins and phenicol antibiotics were achieved using MAA-incorporated column. - Abstract: In this study, methacrylic acid (MAA) was incorporated with alkyl methacrylates to increase the hydrophilicity of the synthesized ethylene dimethacrylate-based (EDMA-based) monoliths for separating polar small molecules by capillary LC analysis. Different alkyl methacrylate–MAA ratios were investigated to prepare a series of 30% alkyl methacrylate–MAA–EDMA monoliths in fused-silica capillaries (250-μm i.d.). The porosity, permeability, and column efficiency of the synthesized MAA-incorporated monolithic columns were characterized. A mixture of phenol derivatives is employed to evaluate the applicability of using the prepared monolithic columns for separating small molecules. Fast separation of six phenol derivatives was achieved in 5 min with gradient elution using the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column. In addition, the effect of acetonitrile content in mobile phase on retention factor and plate height as well as the plate height-flow velocity curves were also investigated to further examine the performance of the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column. Moreover, the applicability of prepared polymer-based monolithic column for potential food safety applications was also demonstrated by analyzing five aflatoxins and three phenicol antibiotics using the selected poly(lauryl methacrylate-co-MAA-co-EDMA) monolithic column.

  18. Derivation of water vapour absorption cross-sections in the red region

    Science.gov (United States)

    Lal, M.; Chakrabarty, D. K.

    1994-01-01

    Absorption spectrum in 436 to 448 nm wavelength region gives NO2 and O3 column densities. This spectrum can also give H2O column density. The spectrum in the range of 655 to 667 nm contains absorption due to NO3 and H2O. Combining the absorption spectra in the wavelength ranges of 436 to 448 and 655 to 667 nm, water vapor absorption cross-sections in this range comes out to be of the order of 2.0 x 10(exp -24) cm(exp -2).

  19. Improved focusing-and-deflection columns

    International Nuclear Information System (INIS)

    Mui, P.H.; Szilagyi, M.

    1995-01-01

    Our earlier design procedures for constructing quadrupole columns are further expanded to include octupole corrector units and ''octupole'' deflectors with no third-order harmonics. The additional complications are finer partitioning of the plates and increased number of voltage controllers. Two sample designs, one having only the additional octupole deflectors and one having both the deflectors and the correctors, are presented and compared to our previous quadrupole system. The additional octupole components are shown to be capable of increasing the current density from 30% to more than 300% for a four-plate system, designed to focus and scan the electron beam over a circular area of 0.25 mm radius. The electron beam is assumed to have an initial divergence of ±2.3 mrad, an initial energy of 6 kV, a total energy spread of 1 eV, and a final acceleration of 30 keV. These systems are then slightly reoptimized for a superficial comparison with the commercially available column by Micrion Corporation. The numerical results indicate a potential for substantial improvements, demonstrating the power of this design procedure. Finally, a discussion is presented on how the individual components can interact with each other to reduce the various aberrations. copyright 1995 American Vacuum Society

  20. Decadal changes in global surface NO

    NARCIS (Netherlands)

    Miyazaki, Kazuyuki; Eskes, Henk; Sudo, Kengo; Boersma, Folkert; Bowman, Kevin; Kanaya, Yugo

    2017-01-01

    Global surface emissions of nitrogen oxides (NOx ) over a 10-year period (2005-2014) are estimated from an assimilation of multiple satellite data sets: tropospheric NO2 columns from Ozone Monitoring Instrument (OMI), Global Ozone Monitoring Experiment-2 (GOME- 2), and

  1. Column-Oriented Database Systems (Tutorial)

    OpenAIRE

    Abadi, D.; Boncz, Peter; Harizopoulos, S.

    2009-01-01

    textabstractColumn-oriented database systems (column-stores) have attracted a lot of attention in the past few years. Column-stores, in a nutshell, store each database table column separately, with attribute values belonging to the same column stored contiguously, compressed, and densely packed, as opposed to traditional database systems that store entire records (rows) one after the other. Reading a subset of a table’s columns becomes faster, at the potential expense of excessive disk-head s...

  2. Measurements of Atmospheric CO2 Column in Cloudy Weather Conditions using An IM-CW Lidar at 1.57 Micron

    Science.gov (United States)

    Lin, Bing; Obland, Michael; Harrison, F. Wallace; Nehrir, Amin; Browell, Edward; Campbell, Joel; Dobler, Jeremy; Meadows, Bryon; Fan, Tai-Fang; Kooi, Susan; hide

    2015-01-01

    This study evaluates the capability of atmospheric CO2 column measurements under cloudy conditions using an airborne intensity-modulated continuous-wave integrated-path-differential-absorption lidar operating in the 1.57-m CO2 absorption band. The atmospheric CO2 column amounts from the aircraft to the tops of optically thick cumulus clouds and to the surface in the presence of optically thin clouds are retrieved from lidar data obtained during the summer 2011 and spring 2013 flight campaigns, respectively.

  3. Chromatographic selectivity of poly(alkyl methacrylate-co-divinylbenzene) monolithic columns for polar aromatic compounds by pressure-driven capillary liquid chromatography

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shu-Ling; Wang, Chih-Chieh; Fuh, Ming-Ren, E-mail: msfuh@scu.edu.tw

    2016-10-05

    In this study, divinylbenzene (DVB) was used as the cross-linker to prepare alkyl methacrylate (AlMA) monoliths for incorporating π-π interactions between the aromatic analytes and AlMA-DVB monolithic stationary phases in capillary LC analysis. Various AlMA/DVB ratios were investigated to prepare a series of 30% AlMA-DVB monolithic stationary phases in fused-silica capillaries (250-μm i.d.). The physical properties (such as porosity, permeability, and column efficiency) of the synthesized AlMA-DVB monolithic columns were investigated for characterization. Isocratic elution of phenol derivatives was first employed to evaluate the suitability of the prepared AlMA-DVB columns for small molecule separation. The run-to-run (0.16–1.20%, RSD; n = 3) and column-to-column (0.26–2.95%, RSD; n = 3) repeatabilities on retention times were also examined using the selected AlMA-DVB monolithic columns. The π-π interactions between the aromatic ring and the DVB-based stationary phase offered better recognition on polar analytes with aromatic moieties, which resulted in better separation resolution of aromatic analytes on the AlMA-DVB monolithic columns. In order to demonstrate the capability of potential environmental and/or food safety applications, eight phenylurea herbicides with single benzene ring and seven sulfonamide antibiotics with polyaromatic moieties were analyzed using the selected AlMA-DVB monolithic columns. - Highlights: • First investigation on chromatographic selectivity of AlMA-DVB monolithic columns. • Good run-to-run/column-to-column repeatability (<3%) on AlMA-DVB monolithic columns. • Efficient separation of phenylurea herbicides and sulfonamides on AlMA-DVB columns.

  4. Nuclear reactor control column

    International Nuclear Information System (INIS)

    Bachovchin, D.M.

    1982-01-01

    The nuclear reactor control column comprises a column disposed within the nuclear reactor core having a variable cross-section hollow channel and containing balls whose vertical location is determined by the flow of the reactor coolant through the column. The control column is divided into three basic sections wherein each of the sections has a different cross-sectional area. The uppermost section of the control column has the greatest crosssectional area, the intermediate section of the control column has the smallest cross-sectional area, and the lowermost section of the control column has the intermediate cross-sectional area. In this manner, the area of the uppermost section can be established such that when the reactor coolant is flowing under normal conditions therethrough, the absorber balls will be lifted and suspended in a fluidized bed manner in the upper section. However, when the reactor coolant flow falls below a predetermined value, the absorber balls will fall through the intermediate section and into the lowermost section, thereby reducing the reactivity of the reactor core and shutting down the reactor

  5. The influence of aerosols and land-use type on NO2 satellite retrieval over China

    Science.gov (United States)

    Liu, Mengyao; Lin, Jintai; Boersma, Folkert; Eskes, Henk; Chimot, Julien

    2017-04-01

    Both aerosols and surface reflectance have a strong influence on the retrieval of NO2 tropospheric vertical column densities (VCDs), especially over China with its heavy aerosol loading and rapid changes in land-use type. However, satellite retrievals of NO2 VCDs usually do not explicitly account for aerosol optical effects and surface reflectance anisotropy (BRDF) that varies in space and time. We develop an improved algorithm to derive tropospheric AMFs and VCDs over China from the OMI instrument - POMINO and DOMINO. This method can also be applied to TropOMI NO2 retrievals in the future. With small pixels of TropOMI and higher probability of encountering clear-sky scenes, the influence of BRDF and aerosol interference becomes more important than for OMI. Daily aerosol information is taken from the GEOS-Chem chemistry transport model and the aerosol optical depth (AOD) is adjusted via MODIS AOD climatology. We take the MODIS MCD43C2 C5 product to account for BRDF effects. The relative altitude of NO2 and aerosols is critical factor influencing the NO2 retrieval. In order to evaluate the aerosol extinction profiles (AEP) of GEOS-Chem improve our algorithm, we compare the GEOS-Chem simulation with CALIOP and develop a CALIOP AEP climatology to regulate the model's AEP. This provides a new way to include aerosol information into the tracer gas retrieval for OMI and TropOMI. Preliminary results indicate that the model performs reasonably well in reproducing the AEP shape. However, it seems to overestimate aerosols under 2km and underestimate above. We find that relative humidity (RH) is an important factor influencing the AEP shape when comparing the model with observations. If we adjust the GEOS-Chem RH to CALIOP's RH, the correlations of their AEPs also improve. Besides, take advantage of our retrieval method, we executed sensitivity tests to analyze their influences on NO2 trend and spatiotemporal variations in retrieval. It' the first time to investigate

  6. 2D fall of granular columns controlled by slow horizontal withdrawal of a retaining wall

    Science.gov (United States)

    Mériaux, C. A.

    2006-12-01

    This paper describes a series of experiments designed to investigate the fall of granular columns in quasi- static regime. Columns made of alternatively green and red sand layers were initially laid out in a box and then released when a retaining wall was set in slow motion with constant speed. The dependence of the dynamics of the fall on the initial aspect ratio of the columns, the velocity of the wall and the material properties was investigated within the quasi-static regime. A change in the behaviour of the columns was identified to be a function of the aspect ratio (height/length) of the initial sand column. Columns of high aspect ratio first subsided before sliding along failure planes, while columns of small aspect ratio were only observed to slide along failure planes. The transition between these two characteristic falls occurred regardless of the material and the velocity of the wall in the context of the quasi-static regime. When the final height and length of the piles were analyzed, we found power-law relations of the ratio of initial to final height and final run-out to initial length with the aspect ratio of the column. The dissipation of energy is also shown to increase with the run-out length of the pile until it reaches a plateau.

  7. Column Selection for Biomedical Analysis Supported by Column Classification Based on Four Test Parameters.

    Science.gov (United States)

    Plenis, Alina; Rekowska, Natalia; Bączek, Tomasz

    2016-01-21

    This article focuses on correlating the column classification obtained from the method created at the Katholieke Universiteit Leuven (KUL), with the chromatographic resolution attained in biomedical separation. In the KUL system, each column is described with four parameters, which enables estimation of the FKUL value characterising similarity of those parameters to the selected reference stationary phase. Thus, a ranking list based on the FKUL value can be calculated for the chosen reference column, then correlated with the results of the column performance test. In this study, the column performance test was based on analysis of moclobemide and its two metabolites in human plasma by liquid chromatography (LC), using 18 columns. The comparative study was performed using traditional correlation of the FKUL values with the retention parameters of the analytes describing the column performance test. In order to deepen the comparative assessment of both data sets, factor analysis (FA) was also used. The obtained results indicated that the stationary phase classes, closely related according to the KUL method, yielded comparable separation for the target substances. Therefore, the column ranking system based on the FKUL-values could be considered supportive in the choice of the appropriate column for biomedical analysis.

  8. Improvements in solvent extraction columns

    International Nuclear Information System (INIS)

    Aughwane, K.R.

    1987-01-01

    Solvent extraction columns are used in the reprocessing of irradiated nuclear fuel. For an effective reprocessing operation a solvent extraction column is required which is capable of distributing the feed over most of the column. The patent describes improvements in solvent extractions columns which allows the feed to be distributed over an increased length of column than was previously possible. (U.K.)

  9. Axial holdup in pulsed perforated-plate column of pulser feeder type, (2)

    International Nuclear Information System (INIS)

    Ikeda, Hidematsu; Suzuki, Atsuyuki; Kiyose, Ryohei.

    1987-01-01

    In mathematical models for a pulsed perforated-plate column, the dispersed phase holdup has been considered to be uniform throughout the length of the column, but fairly recently it is treated as being nonuniform. In the previous paper, the axial holdup data were obtained in the dispersed aqueous and the dispersed organic modes. Experimental results showed that the axial holdup data become nonuniform throughout the column. It was also found that both of the plate type and the operation mode affected the axial holdup distribution. The present work is an attempt to formulate the axial holdup by means of a heuristic selforganization method that provides a nonlinear prediction model of complex system, since the holdup data did not directly show so significant trend as to formulate the axial holdup. The Group Method of Data Handling (GMDH) is used for this purpose. The GMDH can be used for selection and synthesis of input variables concerned with the axial holdup for the pulsed perforated-plate column. The axial holdup data have been successfully correlated and the identification models could be useful in discussing mathematical models. (author)

  10. Analysis of 2-methylthio-derivatives of isoprenoid cytokinins by liquid chromatography-tandem mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Tarkowski, Petr, E-mail: petr.tarkowski@upol.cz [Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Biochemistry, Faculty of Science, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Vaclavikova, Katerina, E-mail: katka.vaclavik@seznam.cz [Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Department of Biochemistry, Faculty of Science, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Novak, Ondrej, E-mail: ondrej.novak@upol.cz [Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Pertry, Ine, E-mail: ine.pertry@ugent.BE [Department of Plant Biotechnology and Genetics, Ghent University, K.L.Ledeganckstraat 35, B-9000 Gent (Belgium); Hanus, Jan, E-mail: helehan@seznam.cz [Isotope Laboratory, Institute of Experimental Botany ASCR, Videnska 1083, 142 20 Prague (Czech Republic); Whenham, Robert [Apex Organics, Devon, England (United Kingdom); Vereecke, Danny, E-mail: danny.vereecke@hogent.BE [Department of Plant Production, University College Ghent, Ghent University, Schoonmeersstraat 52, B-9000 Gent (Belgium); Sebela, Marek, E-mail: marek.sebela@upol.cz [Department of Biochemistry, Faculty of Science, Palacky University, Slechtitelu 11, 783 71 Olomouc (Czech Republic); Strnad, Miroslav, E-mail: miroslav.strnad@upol.cz [Laboratory of Growth Regulators, Palacky University and Institute of Experimental Botany ASCR, Slechtitelu 11, 783 71 Olomouc (Czech Republic)

    2010-11-08

    A sensitive and reliable high-performance liquid chromatographic method with tandem mass spectrometric detection has been developed and used for the determination of 2-methylthio-cytokinin derivatives produced by the phytopathogenic actinomycete Rhodococcus fascians. The cultivation medium containing secreted cytokinins was concentrated and subjected to a solid-phase extraction (C18 and ion-exchange). The purified samples were further separated and analyzed by HPLC-ESI-MS/MS. This allowed to achieve chromatographic resolution of six highly hydrophobic cytokinin species including 2-methylthio-isopentenyladenine, 2-methylthio-isopentenyladenosine, 2-methylthio-trans-zeatin and 2-methylthio-trans-zeatin riboside and their cis-isomers when a reversed-phase chromatographic column (C4) and a mobile phase consisting of acetonitrile and 20 mM ammonium formate, pH 5, were used. Quantification was performed by a standard isotope dilution method using a multiple-reaction monitoring (MRM) mode. In the MRM mode, limits of detection reached 20-30 fmol and linear ranges spanned four orders of magnitude. Recovery values were between 35% and 65% and the analytical accuracy between 95% and 149%. The proposed bioanalytical method, which takes advantage of effective chromatographic separation of six 2-methyltio-derivatives (including isomers of zeatin-type cytokinins) and sensitive mass spectrometric detection, may become useful for plant biologists studying the significance of these substances in plant-microbe interactions.

  11. Analysis of 2-methylthio-derivatives of isoprenoid cytokinins by liquid chromatography-tandem mass spectrometry

    International Nuclear Information System (INIS)

    Tarkowski, Petr; Vaclavikova, Katerina; Novak, Ondrej; Pertry, Ine; Hanus, Jan; Whenham, Robert; Vereecke, Danny; Sebela, Marek; Strnad, Miroslav

    2010-01-01

    A sensitive and reliable high-performance liquid chromatographic method with tandem mass spectrometric detection has been developed and used for the determination of 2-methylthio-cytokinin derivatives produced by the phytopathogenic actinomycete Rhodococcus fascians. The cultivation medium containing secreted cytokinins was concentrated and subjected to a solid-phase extraction (C18 and ion-exchange). The purified samples were further separated and analyzed by HPLC-ESI-MS/MS. This allowed to achieve chromatographic resolution of six highly hydrophobic cytokinin species including 2-methylthio-isopentenyladenine, 2-methylthio-isopentenyladenosine, 2-methylthio-trans-zeatin and 2-methylthio-trans-zeatin riboside and their cis-isomers when a reversed-phase chromatographic column (C4) and a mobile phase consisting of acetonitrile and 20 mM ammonium formate, pH 5, were used. Quantification was performed by a standard isotope dilution method using a multiple-reaction monitoring (MRM) mode. In the MRM mode, limits of detection reached 20-30 fmol and linear ranges spanned four orders of magnitude. Recovery values were between 35% and 65% and the analytical accuracy between 95% and 149%. The proposed bioanalytical method, which takes advantage of effective chromatographic separation of six 2-methyltio-derivatives (including isomers of zeatin-type cytokinins) and sensitive mass spectrometric detection, may become useful for plant biologists studying the significance of these substances in plant-microbe interactions.

  12. Temperature-assisted On-column Solute Focusing: A General Method to Reduce Pre-column Dispersion in Capillary High Performance Liquid Chromatography

    Science.gov (United States)

    Groskreutz, Stephen R.; Weber, Stephen G.

    2014-01-01

    Solvent-based on-column focusing is a powerful and well known approach for reducingthe impact of pre-column dispersion in liquid chromatography. Here we describe an orthogonal temperature-based approach to focusing called temperature-assisted on-column solute focusing (TASF). TASF is founded on the same principles as the more commonly used solvent-based method wherein transient conditions are created thatlead to high solute retention at the column inlet. Combining the low thermal mass of capillary columns and the temperature dependence of solute retentionTASF is used effectivelyto compress injection bands at the head of the column through the transient reduction in column temperature to 5 °C for a defined 7 mm segment of a 6 cm long 150 μm I.D. column. Following the 30 second focusing time, the column temperature is increased rapidly to the separation temperature of 60 °C releasing the focused band of analytes. We developed a model tosimulate TASF separations based on solute retention enthalpies, focusing temperature, focusing time, and column parameters. This model guides the systematic study of the influence of sample injection volume on column performance.All samples have solvent compositions matching the mobile phase. Over the 45 to 1050 nL injection volume range evaluated, TASF reducesthe peak width for all soluteswith k’ greater than or equal to 2.5, relative to controls. Peak widths resulting from injection volumes up to 1.3 times the column fluid volume with TASF are less than 5% larger than peak widths from a 45 nL injection without TASF (0.07 times the column liquid volume). The TASF approach reduced concentration detection limits by a factor of 12.5 relative to a small volume injection for low concentration samples. TASF is orthogonal to the solvent focusing method. Thus, it canbe used where on-column focusing is required, but where implementation of solvent-based focusing is difficult. PMID:24973805

  13. [Characteristics of atmospheric NO2 in the Beijing-Tianjin-Hebei region and the Yangtze River Delta analyzed by satellite and ground observations].

    Science.gov (United States)

    Wang, Ying; Li, Ling-Jun; Liu, Yang

    2012-11-01

    The interannual variability of NO2 levels in two major Chinese economic regions, the Beijing-Tianjin-Hebei (BTH) economic circle and the Yangtze River Delta (YRD), were studied using multiple years of OMI-retrieved NO2 columns and ground measurements. The NO2 columns were comparable in the two regions, which were - 50% higher than the BTH and YRD regional background and two times higher than the Asia-Europe continental background. Satellite data showed that the high NO2 regions scattered around Beijing and Shanghai in summer, and the coverage of high NO2 regions increased in spring and merged in winter, affecting the entire eastern China. Ground level NO2 concentrations in the urban centers of Beijing and Shanghai were also comparable, which were - 10 times greater than the regional background and 1 000 times higher than the Asia-Europe continental background. As industries gradually migrated out of the urban centers, the NO2 concentrations in Beijing and Shanghai decreased, but the regional background NO2 concentration in BTH and YRD increased. It reflected in part the impact of NO2 emission reductions related to fossil fuel combustion as a result of air quality control measures in BTH and YRD. NO2 levels during the Beijing 2008 Olympic Games and the Shanghai World Expo 2010 decreased temporarily, but bounced back quickly afterwards, indicating that sustainable air quality improvement can only be achieved through long-term regional efforts.

  14. Full-Physics Inverse Learning Machine for Satellite Remote Sensing of Ozone Profile Shapes and Tropospheric Columns

    Science.gov (United States)

    Xu, J.; Heue, K.-P.; Coldewey-Egbers, M.; Romahn, F.; Doicu, A.; Loyola, D.

    2018-04-01

    Characterizing vertical distributions of ozone from nadir-viewing satellite measurements is known to be challenging, particularly the ozone information in the troposphere. A novel retrieval algorithm called Full-Physics Inverse Learning Machine (FP-ILM), has been developed at DLR in order to estimate ozone profile shapes based on machine learning techniques. In contrast to traditional inversion methods, the FP-ILM algorithm formulates the profile shape retrieval as a classification problem. Its implementation comprises a training phase to derive an inverse function from synthetic measurements, and an operational phase in which the inverse function is applied to real measurements. This paper extends the ability of the FP-ILM retrieval to derive tropospheric ozone columns from GOME- 2 measurements. Results of total and tropical tropospheric ozone columns are compared with the ones using the official GOME Data Processing (GDP) product and the convective-cloud-differential (CCD) method, respectively. Furthermore, the FP-ILM framework will be used for the near-real-time processing of the new European Sentinel sensors with their unprecedented spectral and spatial resolution and corresponding large increases in the amount of data.

  15. File list: NoD.PSC.05.AllAg.hESC_derived_neural_cells [Chip-atlas[Archive

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    Full Text Available NoD.PSC.05.AllAg.hESC_derived_neural_cells hg19 No description Pluripotent stem cell hESC derived neural...edbc.jp/kyushu-u/hg19/assembled/NoD.PSC.05.AllAg.hESC_derived_neural_cells.bed ...

  16. File list: NoD.PSC.50.AllAg.hESC_derived_neural_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.PSC.50.AllAg.hESC_derived_neural_cells hg19 No description Pluripotent stem cell hESC derived neural...edbc.jp/kyushu-u/hg19/assembled/NoD.PSC.50.AllAg.hESC_derived_neural_cells.bed ...

  17. File list: NoD.PSC.20.AllAg.hESC_derived_neural_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.PSC.20.AllAg.hESC_derived_neural_cells hg19 No description Pluripotent stem cell hESC derived neural...edbc.jp/kyushu-u/hg19/assembled/NoD.PSC.20.AllAg.hESC_derived_neural_cells.bed ...

  18. File list: NoD.PSC.10.AllAg.hESC_derived_neural_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  19. Hydrothermal synthesis and magneto-optical properties of Ni-doped ZnO hexagonal columns

    International Nuclear Information System (INIS)

    Xu, Xingyan; Cao, Chuanbao

    2015-01-01

    Single crystal Zn 1−x Ni x O (x=0, 0.02, 0.04, 0.06) hexagonal columns have been synthesized by a simple hydrothermal route. The hexagonal columns of the products are about 3 μm in diameter and about 2 μm in thickness. X-ray diffraction (XRD), Ni K-edge XANES spectra and TEM indicate that the as-prepared samples are single-crystalline wurtzite structure and no metallic Ni or other secondary phases are found in the hexagonal columns. Optical absorption and Raman results further confirm the incorporation of Ni 2+ ions in the ZnO lattice. Magnetic measurements indicate that the Zn 1−x Ni x O hexagonal columns exhibited obvious ferromagnetic characteristic at room temperature. The coercive fields (H c ) were obtained to be 135.3, 327.79 and 127.29 Oe for x=0.02, 0.04 and 0.06, respectively. The ferromagnetism was assumed to originate from the exchange interaction between free carriers (holes or electrons) from the valence band and the localized d spins on the Ni ions. - Highlights: • Single crystal Zn 1−x Ni x O (x=0, 0.02, 0.04, 0.06) hexagonal columns were synthesized by a simple hydrothermal method. • The layer-by-layer growth manner of the Zn 1−x Ni x O hexagonal columns was proposed. • Obvious room-temperature ferromagnetic characteristic of Zn 1−x Ni x O are observed and the coercivity (H c ) are 135.3,327.79 and 127.29 Oe for x=0.02, 0.04 and 0.06, respectively. • The exchange interaction between local-spin polarized electrons and conduction electrons is responsible for the room-temperature ferromagnetism in the Zn 1−x Ni x O hexagonal columns

  20. Remote sensing of stratospheric O{sub 3} and NO{sub 2} using a portable and compact DOAS spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Raponi, M M; Wolfram, E; Quel, E J [Division LIDAR, Centro de Investigaciones en Laseres y Aplicaciones, CEILAP (CITEFA-CONICET), Juan B. de La Salle 4397 (B1603ALO), Villa Martelli, Buenos Aires (Argentina); Jimenez, R [Department of Chemical and Environmental Engineering, Universidad Nacional de Colombia, Bogota (Colombia); Tocho, J O, E-mail: mraponi@citefa.gov.ar [Centro de Investigaciones Opticas, CIOp (CONICET La Plata-CIC), Buenos Aires (Argentina)

    2011-01-01

    The use of passive and active remote sensing systems has largely contributed to advance our understanding of important atmospheric phenomena. Here we present a compact and portable passive DOAS (Differential Optical Absorption Spectroscopy) system, developed for measuring the vertical column density (VCD) of multiple atmospheric trace gases. We highlight the main characteristics of the system components: a mini-spectrometer (HR4000, Ocean Optics), two optical fibers (400 {mu}m of core, 6 m and 25 cm of longitude), an external shutter and the control/data processing software. Nitrogen dioxide (NO{sub 2}) and ozone (O{sub 3}) VCDs are derived from solar spectra acquired during twilights (87{sup 0} - 91{sup 0} zenithal angles) using the DOAS technique. The analysis is carried out by solving the Beer-Lambert-Bouger (BLB) law for the main atmospheric absorbers at selected wavelength ranges. The algorithm minimizes the fitting residuals to the BLB law, having as unknown the slant column density (SCD) of the species to determine. We present measurements carried out at the Marambio Antarctic Base (64{sup 0} 14' 25'' S; 56{sup 0} 37' 21'' W, 197 m asl) during January - February 2008. In addition, we compare our results with co-located measurements performed with EVA, a visible absorption spectrometer of Instituto Nacional de Tecnica Aeroespacial (INTA, Spain), a Dobson spectrophotometer of Servicio Meteorologico Nacional (SMN, Argentine) and the Ozone Monitoring Instrument (OMI), on board AURA satellite.

  1. LIQUID-LIQUID EXTRACTION COLUMNS

    Science.gov (United States)

    Thornton, J.D.

    1957-12-31

    This patent relates to liquid-liquid extraction columns having a means for pulsing the liquid in the column to give it an oscillatory up and down movement, and consists of a packed column, an inlet pipe for the dispersed liquid phase and an outlet pipe for the continuous liquid phase located in the direct communication with the liquid in the lower part of said column, an inlet pipe for the continuous liquid phase and an outlet pipe for the dispersed liquid phase located in direct communication with the liquid in the upper part of said column, a tube having one end communicating with liquid in the lower part of said column and having its upper end located above the level of said outlet pipe for the dispersed phase, and a piston and cylinder connected to the upper end of said tube for applying a pulsating pneumatic pressure to the surface of the liquid in said tube so that said surface rises and falls in said tube.

  2. Radio Column Chromatographic Assay of H3-Labelled Substances

    International Nuclear Information System (INIS)

    Scharpenseel, H.W.; Menke, K.H.

    1962-01-01

    Combined radio-chromatographic investigations of H 3 -labelled substances are an integral part of the majority of biochemical experiments with H 3 -labelled compounds. H 3 -radio paper chromatography yields, in a scanner with a windowless flow counter, a counting efficiency of 0,5 -1,5%, depending largely on the thickness of the paper and the self-absorption of the labelled compound. The radio gas chromatography of tritiated compounds presents no major problem. Successful use is being made of a combination of a gas chromatograph with a flow ionization chamber and vibrating reed electrometer, a system originated by K. E. Wilzbach and P. Riessz, and improved by H. Dutton, L. Mason and L. Blair. Through the use of ''Teflon'' and silicone-rubber for the insulating parts of the flow ion chamber, it can be operated at close to 300 o C. Radio column chromatography with tritium holds little promise, when the column effluent is spread out as a shallow layer and slowly passes under a windowless flow counter or a scintillation counter, as was successfully tried with C 14 . Liquid scintillation spectrometry is likely to be the chosen method. Essentially, there are two different approaches feasible. These have been compared: 1. The column effluent is passed through a coil of plastic scintillator tubing, which is wound around a ''Plexiglas'' cylinder and placed in a bath of silicone oil in a light pipe with TiO 2 -reflector. Similarly, the HP-containing effluent can be directed through a test vial, filled - very much as in Steinberg's method - with plastic scintillator beads. These two approaches, that operate highly satisfactorily in the case of C 14 , offer low counting efficiencies of less than 1% for H 3 due to the unfavourable surface to volume ratio. 2. The column effluent is combined 1:30 with a mixture of 3:2 toluene/ethanol by the action of a magnet-vibrator before being assayed while passing through a K 40 -free glass - coiled between the analyser- and monitor

  3. Transport of perfluoroalkyl acids in a water-saturated sediment column investigated under near-natural conditions

    International Nuclear Information System (INIS)

    Vierke, Lena; Möller, Axel; Klitzke, Sondra

    2014-01-01

    The aim of this study was to gain an understanding of the transport of C 4–10 perfluoroalkyl carboxylic acids (PFCAs) and C 4,6,8 perfluoroalkyl sulfonic acids (PFSAs) in a water-saturated sediment column representing a riverbank filtration scenario under near-natural conditions. Short-chain PFCAs and PFSAs with up to six C-atoms showed complete tracer-like breakthrough. Longer chain ones were retarded due to sorption to the sediment or due to other processes in the aqueous phase. The study reports the first column derived sediment–water partition coefficients ranging from 0.01 cm 3 g −1 to 0.41 cm 3 g −1 for C 4,6 PFSAs and from 0.0 cm 3 g −1 to 6.5 cm 3 g −1 for C 4,5,6,8,9 PFCAs. The results clearly indicate that short-chain PFCAs and PFSAs may pose a problem if contaminated surface waters are used for drinking water production via riverbank filtration. Highlights: • Transport of per- and polyfluorinated compounds in a riverbank filtration scenario. • Investigations under near-natural conditions with a water-saturated sediment column. • Processes in water and sediment control the transport of analytes. • Short chain PFCAs and PFSAs are not retarded in the water-saturated sediment column. • First column derived sediment–water partition coefficients. -- Quantification of breakthrough of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFSAs) under conditions simulating a riverbank filtration scenario

  4. Development of gas chromatography-flame ionization detection system with a single column and liquid nitrogen-free for measuring atmospheric C2-C12 hydrocarbons.

    Science.gov (United States)

    Liu, Chengtang; Mu, Yujing; Zhang, Chenglong; Zhang, Zhibo; Zhang, Yuanyuan; Liu, Junfeng; Sheng, Jiujiang; Quan, Jiannong

    2016-01-04

    A liquid nitrogen-free GC-FID system equipped with a single column has been developed for measuring atmospheric C2-C12 hydrocarbons. The system is consisted of a cooling unit, a sampling unit and a separation unit. The cooling unit is used to meet the temperature needs of the sampling unit and the separation unit. The sampling unit includes a dehydration tube and an enrichment tube. No breakthrough of the hydrocarbons was detected when the temperature of the enrichment tube was kept at -90 °C and sampling volume was 400 mL. The separation unit is a small round oven attached on the cooling column. A single capillary column (OV-1, 30 m × 0.32 mm I.D.) was used to separate the hydrocarbons. An optimal program temperature (-60 ∼ 170 °C) of the oven was achieved to efficiently separate C2-C12 hydrocarbons. There were good linear correlations (R(2)=0.993-0.999) between the signals of the hydrocarbons and the enrichment amount of hydrocarbons, and the relative standard deviation (RSD) was less than 5%, and the method detection limits (MDLs) for the hydrocarbons were in the range of 0.02-0.10 ppbv for sampling volume of 400 mL. Field measurements were also conducted and more than 50 hydrocarbons from C2 to C12 were detected in Beijing city. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Nano-amylose-2,3-bis(3,5-dimethylphenylcarbamate)-silica hybrid sol immobilized on open tubular capillary column for capillary electrochromatography enantioseparation.

    Science.gov (United States)

    Sun, Yaming; Wu, Qi; Shi, Xiaofeng; Gao, Jie; Dong, Shuqing; Zhao, Liang

    2018-04-01

    The chiral organic-inorganic hybrid materials can exhibit a high loading, and the chiral selector nanoparticles can create efficient stationary phases for open-tubular capillary electrochromatography (OT-CEC). Hence, a novel protocol for the preparation of an OT column coated with nano-amylose-2,3-bis(3,5-dimethylphenylcarbamate) (nano-ABDMPC)-silica hybrid sol through in situ layer-by-layer self-assembly method was developed for CEC enantioseparation. By controlling the assembly cycle number of nano-ABDMPC-silica hybrid sol, a homogeneous, dense and stable coating was successfully prepared, which was confirmed by SEM and elemental analysis. As the main parameter influencing the chiral separating effect, the nano-ABDMPC bearing 3-(triethoxysilyl)propyl residues concentration was investigated. The experimental results showed that 10.0 mg/mL nano-ABDMPC bearing 3-(triethoxysilyl)propyl residues coated OT capillary column possessed chiral recognition ability toward the six enantiomers (phenylalanine, tyrosine, tryptophan, phenethyl alcohol, 1-phenyl-2-propanol, and Tröger's base) at some of the different conditions tested. Additionally, the coated OT column revealed adequate repeatability concerning run-to-run, day-to-day and column-to-column. These results demonstrated the promising applicability of nano-ABDMPC-silica hybrid sol coated OT column in CEC enantioseparations. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. Revised Thermal Analysis of LANL Ion Exchange Column

    Energy Technology Data Exchange (ETDEWEB)

    Laurinat, J

    2006-04-11

    This document updates a previous calculation of the temperature distributions in a Los Alamos National Laboratory (LANL) ion exchange column.1 LANL operates two laboratory-scale anion exchange columns, in series, to extract Pu-238 from nitric acid solutions. The Defense Nuclear Facilities Safety Board has requested an updated analysis to calculate maximum temperatures for higher resin loading capacities obtained with a new formulation of the Reillex HPQ anion exchange resin. The increased resin loading capacity will not exceed 118 g plutonium per L of resin bed. Calculations were requested for normal operation of the resin bed at the minimum allowable solution feed rate of 30 mL/min and after an interruption of flow at the end of the feed stage, when one of the columns is fully loaded. The object of the analysis is to demonstrate that the decay heat from the Pu-238 will not cause resin bed temperatures to increase to a level where the resin significantly degrades. At low temperatures, resin bed temperatures increase primarily due to decay heat. At {approx}70 C a Low Temperature Exotherm (LTE) resulting from the reaction between 8-12 M HNO{sub 3} and the resin has been observed. The LTE has been attributed to an irreversible oxidation of pendant ethyl benzene groups at the termini of the resin polymer chains by nitric acid. The ethyl benzene groups are converted to benzoic acid moities. The resin can be treated to permanently remove the LTE by heating a resin suspension in 8M HNO{sub 3} for 30-45 minutes. No degradation of the resin performance is observed after the LTE removal treatment. In fact, heating the resin in boiling ({approx}115-120 C) 12 M HNO{sub 3} for 3 hr displays thermal stability analogous to resin that has been treated to remove the LTE. The analysis is based on a previous study of the SRS Frames Waste Recovery (FWR) column, performed in support of the Pu-238 production campaign for NASA's Cassini mission. In that study, temperature transients

  7. File list: NoD.PSC.10.AllAg.hESC_derived_neural_crests [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  8. File list: NoD.PSC.05.AllAg.iPS_derived_neural_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  9. File list: NoD.PSC.20.AllAg.hESC_derived_neural_crests [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  10. Hydrogen peroxide stabilization in one-dimensional flow columns

    Science.gov (United States)

    Schmidt, Jeremy T.; Ahmad, Mushtaque; Teel, Amy L.; Watts, Richard J.

    2011-09-01

    Rapid hydrogen peroxide decomposition is the primary limitation of catalyzed H 2O 2 propagations in situ chemical oxidation (CHP ISCO) remediation of the subsurface. Two stabilizers of hydrogen peroxide, citrate and phytate, were investigated for their effectiveness in one-dimensional columns of iron oxide-coated and manganese oxide-coated sand. Hydrogen peroxide (5%) with and without 25 mM citrate or phytate was applied to the columns and samples were collected at 8 ports spaced 13 cm apart. Citrate was not an effective stabilizer for hydrogen peroxide in iron-coated sand; however, phytate was highly effective, increasing hydrogen peroxide residuals two orders of magnitude over unstabilized hydrogen peroxide. Both citrate and phytate were effective stabilizers for manganese-coated sand, increasing hydrogen peroxide residuals by four-fold over unstabilized hydrogen peroxide. Phytate and citrate did not degrade and were not retarded in the sand columns; furthermore, the addition of the stabilizers increased column flow rates relative to unstabilized columns. These results demonstrate that citrate and phytate are effective stabilizers of hydrogen peroxide under the dynamic conditions of one-dimensional columns, and suggest that citrate and phytate can be added to hydrogen peroxide before injection to the subsurface as an effective means for increasing the radius of influence of CHP ISCO.

  11. On a system of differential equations with fractional derivatives arising in rod theory

    International Nuclear Information System (INIS)

    Atanackovic, Teodor M; Stankovic, Bogoljub

    2004-01-01

    We study a system of equations with fractional derivatives, that arises in the analysis of the lateral motion of an elastic column fixed at one end and loaded by a concentrated follower force at the other end. We assume that the column is positioned on a viscoelastic foundation described by a constitutive equation of fractional derivative type. The stability boundary is determined. It is shown that as in the case of an elastic (Winkler) type of foundation the stability boundary remains the same as for the column without a foundation! Thus, with the solution analysed here, the column exhibits the so-called Hermann-Smith paradox

  12. Measurement of purine derivatives and creatinine in urine by HPLC

    International Nuclear Information System (INIS)

    Piani, B.; Fabro, C.; Susmel, P.

    2004-01-01

    Two HPLC methods to measure the purine derivatives (PD, including allantoin, uric acid, hypoxanthine and xanthine) and creatinine content in urine are described. PD separation and quantification were achieved using two Spherisorb ODS 2 reversed phase columns connected in series (4.6 x 250 mm) and a Spherisorb ODS 2 Waters pre-column and a Perkin Elmer pump with an auto sampler. The mobile phase was NH 4 H 2 PO 4 :NH 4 H 2 PO 4 -acetonitrile (80:20), which was used at a flow rate of 0.8 ml/min and the detection wavelength was at 190 nm. The average recoveries of standard compounds added to urine samples were satisfactory (92-106%) and the low detection limits (0.7-3.4 μM) permitted the precise determination of these compounds in urine. Separation and quantification of creatinine was achieved using one Spherisorb ODS 2 reversed phase column (4.6 x 250 mm) and one Spherisorb ODS 2 Waters pre-column and a Perkin Elmer pump with an auto sampler. The mobile phase was NH 4 H 2 PO 4 :NH 4 H 2 PO 4 -acetonitrile (80:20), used at a flow rate of 1.00 ml/min and the detection was at 190 nm. The mean recovery (3 measurements) of standard solution added to urine samples was 101%; detection limit was 7.9 μM. (author)

  13. Inert carriers for column extraction chromatography

    International Nuclear Information System (INIS)

    Katykhin, G.S.

    1978-01-01

    Inert carriers used in column extraction chromatography are reviewed. Such carriers are devided into two large groups: hydrophilic carriers which possess high surface energy and are well wetted only with strongly polar liquids (kieselguhrs, silica gels, glasses, cellulose, Al 2 O 3 ) and water-repellent carriers which possess low surface energy and are well wetted with various organic solvents (polyethylene, polytetrafluorethylene polytrifluorochlorethylene). Properties of various carriers are presented: structure, chemical and radiation stability, adsorption properties, extracting agent capacity. The effect of structure and sizes of particles on the efficiency of chromatography columns is considered. Ways of immovable phase deposition on the carrier and the latter's regeneration. Peculiarities of column packing for preparative and continuous chromatography are discussed

  14. File list: NoD.PSC.10.AllAg.mESC_derived_pancreatic_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.PSC.10.AllAg.mESC_derived_pancreatic_cells mm9 No description Pluripotent stem cell mESC derived panc...reatic cells http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/NoD.PSC.10.AllAg.mESC_derived_pancreatic_cells.bed ...

  15. File list: NoD.PSC.20.AllAg.mESC_derived_pancreatic_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  16. File list: NoD.PSC.50.AllAg.mESC_derived_pancreatic_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  17. File list: NoD.PSC.10.AllAg.mESC_derived_neural_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  18. File list: NoD.PSC.05.AllAg.mESC_derived_neural_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

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  19. File list: NoD.PSC.20.AllAg.mESC_derived_neural_cells [Chip-atlas[Archive

    Lifescience Database Archive (English)

    Full Text Available NoD.PSC.20.AllAg.mESC_derived_neural_cells mm9 No description Pluripotent stem cell mESC derived neural... cells SRX440731,SRX440736 http://dbarchive.biosciencedbc.jp/kyushu-u/mm9/assembled/NoD.PSC.20.AllAg.mESC_derived_neural_cells.bed ...

  20. Validation of SCIAMACHY limb NO2 profiles using solar occultation measurements

    Directory of Open Access Journals (Sweden)

    H. Bovensmann

    2012-05-01

    Full Text Available The increasing amounts of reactive nitrogen in the stratosphere necessitate accurate global measurements of stratospheric nitrogen dioxide (NO2. Over the past decade, the SCIAMACHY (SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY instrument on ENVISAT (European Environmental Satellite has been providing global coverage of stratospheric NO2 every 6 days. In this study, the vertical distributions of NO2 retrieved from SCIAMACHY limb measurements of the scattered solar light are validated by comparison with NO2 products from three different satellite instruments (SAGE II, HALOE and ACE-FTS. The retrieval algorithm based on the information operator approach is discussed, and the sensitivity of the SCIAMACHY NO2 limb retrievals is investigated. The photochemical corrections needed to make this validation feasible, and the chosen collocation criteria are described. For each instrument, a time period of two years is analyzed with several hundreds of collocation pairs for each year. As NO2 is highly variable, the comparisons are performed for five latitudinal bins and four seasons. In the 20 to 40 km altitude range, mean relative differences between SCIAMACHY and other instruments are found to be typically within 20 to 30%. The mean partial NO2 columns in this altitude range agree typically within 15% (both global monthly and zonal annual means. Larger differences are seen for SAGE II comparisons, which is consistent with the results presented by other authors. For SAGE II and ACE-FTS, the observed differences can be partially attributed to the diurnal effect error.

  1. Consolidation Theory for a Stone Column Composite Foundation under Multistage Loading

    Directory of Open Access Journals (Sweden)

    Shenggen Huang

    2016-01-01

    Full Text Available The consolidation theories considering instant load cannot fully reveal the consolidation mechanism of a stone column composite foundation used in the expressway embankments due to the time effect of loading; that is, the expressway embankments are often constructed in several stages for a long time. Meanwhile, owing to the special property that the pile-soil stress ratio is larger than 1, the consolidation theory for sand drain well foundation cannot be used directly in the consolidation analysis of stone column composite foundation. Based on the principle that the vertical load applied on the composite foundation is shared by the stone column and the surrounding soil, the governing solutions for the stone column composite foundation under a multistage load are established. By virtue of the separation of variables, the corresponding solutions of degree of consolidation for loading stage and maintaining load stage are derived separately. According to the Carrillo theorem, the solution for the average total degree of consolidation of entire composite foundation is also obtained. Finally, the reasonableness of the present solution has been verified by comparing the consolidation curve calculated by the present solution with that measured by site test.

  2. Effects of Irregular Bridge Columns and Feasibility of Seismic Regularity

    Science.gov (United States)

    Thomas, Abey E.

    2018-05-01

    Bridges with unequal column height is one of the main irregularities in bridge design particularly while negotiating steep valleys, making the bridges vulnerable to seismic action. The desirable behaviour of bridge columns towards seismic loading is that, they should perform in a regular fashion, i.e. the capacity of each column should be utilized evenly. But, this type of behaviour is often missing when the column heights are unequal along the length of the bridge, allowing short columns to bear the maximum lateral load. In the present study, the effects of unequal column height on the global seismic performance of bridges are studied using pushover analysis. Codes such as CalTrans (Engineering service center, earthquake engineering branch, 2013) and EC-8 (EN 1998-2: design of structures for earthquake resistance. Part 2: bridges, European Committee for Standardization, Brussels, 2005) suggests seismic regularity criterion for achieving regular seismic performance level at all the bridge columns. The feasibility of adopting these seismic regularity criterions along with those mentioned in literatures will be assessed for bridges designed as per the Indian Standards in the present study.

  3. Cervical column morphology and craniofacial profiles in monozygotic twins.

    Science.gov (United States)

    Sonnesen, Liselotte; Pallisgaard, Carsten; Kjaer, Inger

    2008-02-01

    Previous studies have described the relationships between cervical column morphology and craniofacial morphology. The aims of the present study were to describe cervical column morphology in 38 pairs of adult monozygotic (MZ) twins, and compare craniofacial morphology in twins with fusions with craniofacial morphology in twins without fusion. Visual assessment of cervical column morphology and cephalometric measurements of craniofacial morphology were performed on profile radiographs. In the cervical column, fusion between corpora of the second and third vertebrae was registered as fusion. In the twin group, 8 twin pairs had fusion of the cervical column in both individuals within the pair (sub-group A), 25 pairs had no fusions (subgroup B), and in 5 pairs, cervical column morphology was different within the pair (subgroup C), as one twin had fusion and the other did not. Comparison of craniofacial profiles showed a tendency to increased jaw retrognathia, larger cranial base angle, and larger mandibular inclination in subgroup A than in subgroup B. The same tendency was observed within subgroup C between the individual twins with fusion compared with those without fusion. These results confirm that cervical fusions and craniofacial morphology may be interrelated in twins when analysed on profile radiographs. The study also documents that differences in cervical column morphology can occur in individuals within a pair of MZ twins. It illustrates that differences in craniofacial morphology between individuals within a pair of MZ twins can be associated with cervical fusion.

  4. Study on application of single-crystal ice 'Kurobe ice column' to high-speed skating rinks. Demonstration test result at Olympic memorial arena 'M wave' in Nagano city. Tankesshohyo 'Kurobe no hyojun' no kosoku skate link eno tekiyosei kenkyu. Naganoshi olympic kinen arina 'Emu Wave' deno jissho shiken kekka

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, M. (Kansai Electric Power Co. Inc., Osaka (Japan))

    1999-06-10

    For high-speed low-friction skating rinks, research was made on sticking artificial ice columns (ice bamboo shoot). The ice columns were fabricated with the ice column production equipment equipped with 4-line water droplet dropping devices which were installed at intervals of 0.3m on both sides of a pathway of 200m long, 2.6m wide and 1.8m high in the lateral adit of Kurobegawa No.4 hydroelectric power station. The grown ice columns were processed for high-speed skating rinks through cutting, confirmation of single crystal and crystal orientation, slicing for every 7mm thickness and packaging. The ice columns were spread all over the rink while sliding them to prevent mixing of bubbles after spraying distilled water of nearly 25 degreesC onto base ices. In addition, hot water of nearly 40 degreesC was sprayed to produce the final ice rink of 30mm thick by nearly 5mm a day. The dynamic friction coefficient of the ice column rink reduced to 0.0038 by nearly 16% as compared with 0.0045 of conventional rinks. (NEDO)

  5. Modeling water movement in horizontal columns using fractal theory Modelagem de movimento horizontal de água no solo utilizando a teoria dos fractais

    Directory of Open Access Journals (Sweden)

    Tairone Paiva Leão

    2010-08-01

    Full Text Available Fractal mathematics has been used to characterize water and solute transport in porous media and also to characterize and simulate porous media properties. The objective of this study was to evaluate the correlation between the soil infiltration parameters sorptivity (S and time exponent (n and the parameters dimension (D and the Hurst exponent (H. For this purpose, ten horizontal columns with pure (either clay or loam and heterogeneous porous media (clay and loam distributed in layers in the column were simulated following the distribution of a deterministic Cantor Bar with fractal dimension H" 0.63. Horizontal water infiltration experiments were then simulated using Hydrus 2D software. The sorptivity (S and time exponent (n parameters of the Philip equation were estimated for each simulation, using the nonlinear regression procedure of the statistical software package SAS®. Sorptivity increased in the columns with the loam content, which was attributed to the relation of S with the capillary radius. The time exponent estimated by nonlinear regression was found to be less than the traditional value of 0.5. The fractal dimension estimated from the Hurst exponent was 17.5 % lower than the fractal dimension of the Cantor Bar used to generate the columns.A matemática fractal tem sido utilizada para caracterizar o transporte de água e solutos em meios porosos e também para simular características físicas e geométricas de meios porosos. O objetivo deste trabalho foi avaliar a correlação entre os parâmetros de infiltração de água sortividade e expoente de tempo (n e os parâmetros dimensão fractal (D e expoente de Hurst (H. Para isso, dez colunas horizontais foram simuladas em computador, sendo preenchidas com material de textura franca ou argilosa, puros ou em combinações de camadas alternadas dos dois materiais, seguindo a distribuição de um Conjunto de Cantor determinístico com dimensão fractal 0,63. As simulações de movimento

  6. Assessing Spatiotemporal Variability in NO2 and O3 Along the Korean Peninsula Using Remote Sensing and Ground-Based Observations

    Science.gov (United States)

    Li, C. Y. R.; Parker, O.; Tzortziou, M.

    2017-12-01

    Our research sought to use ground-based and satellite products to study the spatiotemporal variability of NO2 and O­3 in urban and coastal South Korea. Our data set was derived from direct-sun irradiance measurements of TCNO2 and TCO3 using Pandora spectrometers located at 8 ground sites and 1 boat-mounted sensor, as well as satellite observations from the Ozone Monitoring Instrument (OMI) on the Aura satellite. Our analysis focuses on the dates of the KORUSA campaign, which took place between May 18, 2016 through June 2, 2016, and provided our off-shore measurements. The Pandora instrument offered us continuous coverage of the local area, providing a detailed understanding of NO2 and O3 temporal variability. Ground stations allowed us to compare small-scale diurnal variability in urban and near-urban environments, while the Pandora mounted on the Onnuri research vessel permitted us to gain valuable insight into off-shore behavior of trace gases. By overlaying and comparing these measurements with TCO3/TCNO2 products from the Aura-OMI sensor, we were able to form a relatively complete picture of trace gas behavior above, and off-shore from, the Korean Peninsula. Our data was then subjected to statistical and GIS (Geographic Information System) analysis, quantifying and mapping (respectively) the spatial and temporal variability of total column amounts of NO2 and O3 along the Korean Peninsula. Results are shown for the eight sites where different Pandora instruments were used. There was a notable difference in TCNO2 variability which correlates with population and land use.

  7. The arctic seasonal cycle of total column CO2 and CH4 from ground-based solar and lunar FTIR absorption spectrometry

    Directory of Open Access Journals (Sweden)

    M. Buschmann

    2017-07-01

    Full Text Available Solar absorption spectroscopy in the near infrared has been performed in Ny-Ålesund (78.9° N, 11.9° E since 2002; however, due to the high latitude of the site, the sun is below the horizon from October to March (polar night and no solar absorption measurements are possible. Here we present a novel method of retrieving the total column dry-air mole fractions (DMFs of CO2 and CH4 using moonlight in winter. Measurements have been taken during the polar nights from 2012 to 2016 and are validated with TCCON (Total Carbon Column Observing Network measurements by solar and lunar absorption measurements on consecutive days and nights during spring and autumn. The complete seasonal cycle of the DMFs of CO2 and CH4 is presented and a precision of up to 0.5 % is achieved. A comparison of solar and lunar measurements on consecutive days during day and night in March 2013 yields non-significant biases of 0. 66 ± 4. 56 ppm for xCO2 and −1. 94 ± 20. 63 ppb for xCH4. Additionally a model comparison has been performed with data from various reanalysis models.

  8. Explicit and Observation-based Aerosol Treatment in Tropospheric NO2 Retrieval over China from the Ozone Monitoring Instrument

    Science.gov (United States)

    Liu, M.; Lin, J.; Boersma, F.; Pinardi, G.; Wang, Y.; Chimot, J.; Wagner, T.; Xie, P.; Eskes, H.; Van Roozendael, M.; Hendrick, F.

    2017-12-01

    Satellite retrieval of vertical column densities (VCDs) of tropospheric nitrogen dioxide (NO2) is influenced by aerosols substantially. Aerosols affect the retrieval of "effective cloud fraction (CF)" and "effective cloud top pressure (CP)" that are used in the subsequent NO2 retrieval to account for the presentence of clouds. And aerosol properties and vertical distributions directly affect the NO2 air mass factor (AMF) calculations. Our published POMINO algorithm uses a parallelized LIDORT-driven AMFv6 code to derive CF, CP and NO2 VCD. Daily information on aerosol optical properties are taken from GEOS-Chem simulations, with aerosol optical depth (AOD) further constrained by monthly MODIS AOD. However, the published algorithm does not include an observation-based constraint of aerosol vertical distribution. Here we construct a monthly climatological observation dataset of aerosol extinction profiles, based on Level-2 CALIOP data over 2007-2015, to further constrain aerosol vertical distributions. GEOS-Chem captures the temporal variations of CALIOP aerosol layer heights (ALH) but has an overall underestimate by about 0.3 km. It tends to overestimate the aerosol extinction by 10% below 2 km but with an underestimate by 30% above 2 km, leading to a low bias by 10-30% in the retrieved tropospheric NO2 VCD. After adjusting GEOS-Chem aerosol extinction profiles by the CALIOP monthly ALH climatology, the retrieved NO2 VCDs increase by 4-16% over China on a monthly basis in 2012. The improved NO2 VCDs are better correlated to independent MAX-DOAS observations at three sites than POMINO and DOMINO are - especially for the polluted cases, R2 reaches 0.76 for the adjusted POMINO, much higher than that for the published POMINO (0.68) and DOMINO (0.38). The newly retrieved CP increases by 60 hPa on average, because of a stronger aerosol screening effect. Compared to the CF used in DOMINO, which implicitly includes aerosol information, our improved CF is much lower and can

  9. Role of notochord cells and sclerotome-derived cells in vertebral column development in fugu, Takifugu rubripes: histological and gene expression analyses.

    Science.gov (United States)

    Kaneko, Takamasa; Freeha, Khalid; Wu, Xiaoming; Mogi, Makoto; Uji, Susumu; Yokoi, Hayato; Suzuki, Tohru

    2016-10-01

    Despite the common structure of vertebrates, the development of the vertebral column differs widely between teleosts and tetrapods in several respects, including the ossification of the centrum and the function of the notochord. In contrast to tetrapods, vertebral development in teleosts is not fully understood, particularly for large fish with highly ossified bones. We therefore examined the histology and gene expression profile of vertebral development in fugu, Takifugu rubripes, a model organism for genomic research. Ossification of the fugu centrum is carried out by outer osteoblasts expressing col1a1, col2a1, and sparc, and the growing centra completely divide the notochord into double cone-shaped segments that function as intercentral joints. In this process, the notochord basal cells produce a thick notochord sheath exhibiting Alcian-blue-reactive cartilaginous properties and composing the intercentral ligament in cooperation with the external ligament connective tissue. Synthesis of the matrix by the basal cells was ascertained by an in vitro test. Expression of twist2 indicates that this connective tissue is descended from the embryonic sclerotome. Notochord basal cells express sox9, ihhb, shh, and col2a1a, suggesting that the signaling system involved in chondrocyte proliferation and matrix production also functions in notochord cells for notochord sheath formation. We further found that the notochord expression of both ntla and shh is maintained in the fugu vertebral column, whereas it is turned off after embryogenesis in zebrafish. Thus, our results demonstrate that, in contrast to zebrafish, a dynamic morphogenesis and molecular network continues to function in fugu until the establishment of the adult vertebral column.

  10. Exogenous factors contributing to column bed heterogeneity: Part 1: Consequences of 'air' injections in liquid chromatography.

    Science.gov (United States)

    Samuelsson, Jörgen; Fornstedt, Torgny; Shalliker, Andrew

    2015-08-07

    It has been shown that not only the packing homogeneity, but also factors external to the column bed, such as, frits and distributors can have important effects on the column performance. This current communication is the first in a series focusing on the impact of exogenous factors on the column bed heterogeneity. This study is based on several observations by us and others that chromatographic runs often, for technical reasons, include more or less portions of air in the injections. It is therefore extremely important to find out the impact of air on the column performance, the reliability of the results derived from analyses where air was injected, and the effect on the column homogeneity. We used a photographic approach for visualising the air transport phenomena, and found that the air transport through the column is comprised of many different types of transport phenomena, such as laminal flow, viscous fingering like flows, channels and bulbs, and pulsations. More particularly, the air clouds within the column definitely interact in the adsorption, i.e. mobile phase adsorbed to the column surface is displaced. In addition, irrespective of the type of air transport phenomena, the air does not penetrate the column homogeneously. This process is strongly flow dependent. In this work we study air transport both in an analytical scale and a semi-prep column. Copyright © 2015. Published by Elsevier B.V.

  11. The passivation of calcite by acid mine water. Column experiments with ferric sulfate and ferric chloride solutions at pH 2

    Energy Technology Data Exchange (ETDEWEB)

    Soler, Josep M. [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia (Spain)], E-mail: jsoler@ija.csic.es; Boi, Marco [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia (Spain); Mogollon, Jose Luis [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Instituto de Ciencias de la Tierra, Universidad Central de Venezuela, Caracas 1020-A (Venezuela, Bolivarian Republic of); Cama, Jordi; Ayora, Carlos [Institute of Earth Sciences ' Jaume Almera' (CSIC), Lluis Sole i Sabaris s/n, 08028 Barcelona, Catalonia (Spain); Institute of Environmental Assessment and Water Research (CSIC), Jordi Girona 18, 08034 Barcelona, Catalonia (Spain); Nico, Peter S.; Tamura, Nobumichi; Kunz, Martin [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA 94720 (United States)

    2008-12-15

    Column experiments, simulating the behavior of passive treatment systems for acid mine drainage, have been performed. Acid solutions (HCl or H{sub 2}SO{sub 4}, pH 2), with initial concentrations of Fe(III) ranging from 250 to 1500 mg L{sup -1}, were injected into column reactors packed with calcite grains at a constant flow rate. The composition of the solutions was monitored during the experiments. At the end of the experiments (passivation of the columns), the composition and structure of the solids were measured. The dissolution of calcite in the columns caused an increase in pH and the release of Ca into the solution, leading to the precipitation of gypsum and Fe-oxyhydroxysulfates (Fe(III)-SO{sub 4}-H{sup +} solutions) or Fe-oxyhydroxychlorides (Fe(III)-Cl-H{sup +} solutions). The columns worked as an efficient barrier for some time, increasing the pH of the circulating solutions from 2 to {approx}6-7 and removing its metal content. However, after some time (several weeks, depending on the conditions), the columns became chemically inert. The results showed that passivation time increased with decreasing anion and metal content of the solutions. Gypsum was the phase responsible for the passivation of calcite in the experiments with Fe(III)-SO{sub 4}-H{sup +} solutions. Schwertmannite and goethite appeared as the Fe(III) secondary phases in those experiments. Akaganeite was the phase responsible for the passivation of the system in the experiments with Fe(III)-Cl-H{sup +} solutions.

  12. Airborne Measurements of CO2 Column Absorption and Range Using a Pulsed Direct-Detection Integrated Path Differential Absorption Lidar

    Science.gov (United States)

    Abshire, James B.; Riris, Haris; Weaver, Clark J.; Mao, Jianping; Allan, Graham R.; Hasselbrack, William E.; Browell, Edward V.

    2013-01-01

    We report on airborne CO2 column absorption measurements made in 2009 with a pulsed direct-detection lidar operating at 1572.33 nm and utilizing the integrated path differential absorption technique. We demonstrated these at different altitudes from an aircraft in July and August in flights over four locations in the central and eastern United States. The results show clear CO2 line shape and absorption signals, which follow the expected changes with aircraft altitude from 3 to 13 km. The lidar measurement statistics were also calculated for each flight as a function of altitude. The optical depth varied nearly linearly with altitude, consistent with calculations based on atmospheric models. The scatter in the optical depth measurements varied with aircraft altitude as expected, and the median measurement precisions for the column varied from 0.9 to 1.2 ppm. The altitude range with the lowest scatter was 810 km, and the majority of measurements for the column within it had precisions between 0.2 and 0.9 ppm.

  13. First Simultaneous Visualization of SO{sub 2} and NO{sub 2} Plume Dispersions using Imaging Differential Optical Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hanlim; Hong, Hyunkee; Han, Kyungsoo [Pukyong National Univ., Busan (Korea, Republic of); Noh, Youngmin [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of); Kwon, Soonchul [Georgia Institute of Technology, Atlanta (United States)

    2014-04-15

    Imaging Differential Optical Absorption Spectroscopy (Imaging-DOAS) has been utilized in recent years to provide slant column density (SCD) distributions of several trace gas species in the plume. The present study introduces a new method using Imaging-DOAS data to determine two-dimensional plume structure from the plume emissions of power plant in conditions of negligible aerosol effects on radiative transfer within the plume. We demonstrates for the first time that two-dimensional distributions of sulfur dioxide (SO{sub 2}) and nitrogen dioxide (NO{sub 2}) in power plant emissions can be determined simultaneously in terms of SCD distribution. The SO{sub 2} SCD values generally decreased with increasing distance from the stack and with distance from the center of the plume. Meanwhile, high NO{sub 2} SCD was observed at locations several hundred meters away from the first stack due to the ratio change of NO to NO{sub 2} in NOx concentration, attributed to the NO oxidation by O{sub 3}. The results of this study show the capability of the Imaging-DOAS technique as a tool to estimate plume dimensions in power plant emissions.

  14. Study on synthesis of {sup 68}GeO{sub 2} and behavior of {sup 68}Ga{sup 3+} Generator column

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Gun Gyun; Lee, Jun Young; Hur, Min Gu; Yang, Srung Dae; Park, Jeong Hoon [Radiation Instrumentation Research Division, Korea Atomic Energy Research Institute (KAERI), Daejeon (Korea, Republic of); Kim, Sang Wook [Dept. of Advanced Materials Chemistry, Dongguk University, Gyeongju (Korea, Republic of)

    2017-02-15

    {sup 68}Ga has emerged as a promising candidate for non-invasive diagnostic imaging within Positron Emission Tomography (PET) because of its advantageous radiochemical characteristics (t{sub 1/2}= 68 min, β{sup +} yield ⁓89%). {sup 68}Ga forms a stable chelation with various ligands and it is possible to be quickly and easily study using a {sup 68}Ge/{sup 68}Ga generator. Commercial {sup 68}Ge/{sup 68}Ga generators are chromatographic system using the inorganic materials such as alumina and tin dioxide which are employed as column matrixes for {sup 68}Ge. In this study, we tried out to make {sup 68}Ge/{sup 68}Ga generator system with the {sup 68}GeO{sub 2} microstructures for column matrix. {sup 68}Ge tends to have stable bond with oxide as {sup 68}GeO{sub 2} microstructures. The {sup 68}GeO{sub 2} has been synthesized by hydrolysis of GeCl{sub 4} (sol-gel method) and characterized by X-ray diffraction and scanning electron microscope for geometrical analysis. The stability of GeO{sub 2} was tested using eluent with diverse solvents (water, ethanol and 0.1 N HCl). The radioactivity of {sup 68}Ga{sup 3+} in eluate through GeO{sub 2} was measured to prove a function as column material for a generation eluate through GeO{sub 2} was measured to prove a function as column material for a generator.

  15. Separation of Alkyne Enantiomers by Chiral Column HPLC Analysis of Their Cobalt-Complexes

    Directory of Open Access Journals (Sweden)

    Qiaoyun Liu

    2017-03-01

    Full Text Available Separation of the enantiomers of new chiral alkynes in strategic syntheses and bioorthogonal studies is always problematic. The chiral column high-performance liquid chromatography (HPLC method in general could not be directly used to resolve such substrates, since the differentiation of the alkyne segment with the other alkane/alkene segment is not significant in the stationary phase, and the alkyne group is not a good UV chromophore. Usually, a pre-column derivatization reaction with a tedious workup procedure is needed. Making use of easily-prepared stable alkyne-cobalt-complexes, we developed a simple and general method by analyzing the in situ generated cobalt-complex of chiral alkynes using chiral column HPLC. This new method is especially suitable for the alkynes without chromophores and other derivable groups.

  16. NMR imaging of the vertebral column and the spinal canal. 2. rev. and enl. ed.

    International Nuclear Information System (INIS)

    Forsting, Michael; Uhlenbrock, Detlev; Wanke, Isabel; Universitaetsklinikum Essen

    2009-01-01

    The book on the MRT (magnetic resonance tomography) of the vertebral cord and spinal canal covers the following topics: physics fundamentals and application; malformation of the spinal canal; degenerative vertebral column diseases; vertebral column and spinal canal carcinomas; inflammatory diseases of the vertebral column and the spinal canal; applicability of MRT in case of acute spinal cord traumata; vascular diseases of the spinal canal

  17. The rate coefficient for the reaction NO2 + NO3 yielding NO + NO2 + O2 from 273 to 313 K

    Science.gov (United States)

    Cantrell, Chris A.; Shetter, Richard E.; Mcdaniel, Anthony H.; Calvert, Jack G.

    1990-01-01

    The ratio of rate constants for the reaction NO3 + NO yielding 2 NO2 (k3) and the reaction NO2 + NO3 yielding NO + NO2 + O2 (k4) were determined by measuring of NO and NO2 concentrations of NO and NO2 in an N2O5/NO2/N2 mixture over the temperature range 273-313 K. The measured ratio was found to be expressed by the equation k3/k4 = 387 exp(-1375/T). The results are consistent with those of Hammer et al. (1986).

  18. Lanthanum-promoted copper-based hydrotalcites derived mixed oxides for NO{sub x} adsorption, soot combustion and simultaneous NO{sub x}-soot removal

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhongpeng [School of Resources and Environment, University of Jinan, 106 Jiwei Road, Jinan 250022 (China); Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Yan, Xiaotong; Bi, Xinlin; Wang, Liguo [School of Resources and Environment, University of Jinan, 106 Jiwei Road, Jinan 250022 (China); Zhang, Zhaoliang, E-mail: chm_zhangzl@ujn.edu.cn [School of Resources and Environment, University of Jinan, 106 Jiwei Road, Jinan 250022 (China); Jiang, Zheng; Xiao, Tiancun [Inorganic Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QR (United Kingdom); Umar, Ahmad [Department of Chemistry, College of Science and Arts, Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Promising Centre for Sensors and Electronic Devices (PCSED), Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Wang, Qiang, E-mail: qiang.wang.ox@gmail.com [College of Environmental Science and Engineering, Beijing Forestry University, 35 Tsinghua East Road, Beijing 100083 (China)

    2014-03-01

    Graphical abstract: - Highlights: • The addition of La in Cu-based oxides increased the types of active oxygen. • NO{sub x} adsorption, soot oxidation and simultaneous NO{sub x}-soot removal were enhanced. • The possible catalytic mechanism was studied via in situ FTIR analysis. • Soot oxidation was promoted by the NO{sub 2} intermediate. - Abstract: La-promoted Cu-based hydrotalcites derived mixed oxides were prepared and their catalytic activities for NO{sub x} adsorption, soot oxidation, and simultaneous NO{sub x}-soot removal were investigated. The catalysts were characterized by XRD, DTG, BET, FTIR, H2-TPR, TPD and TPO techniques. The oxides catalysts exhibited mesoporous properties with specific surface area of 45–160 m{sup 2}/g. The incorporation of La and Cu decreased the amount of basic sites due to the large decrease in surface areas. Under O{sub 2} atmosphere, La incorporation is dominant for soot oxidation activity, while Cu favors high selectivity to CO{sub 2} formation. A synergetic effect between La and Cu for catalyzed soot oxidation lies in the improved redox property and suitable basicity. The presence of NO in O{sub 2} significantly promoted soot oxidation on the catalysts with the ignition temperature decreased to about 300 °C. In O{sub 2}/NO atmosphere, NO{sub 2} acts as an intermediate which oxidizes soot to CO{sub 2} at a lower temperature with itself reduced to NO or N{sub 2}, contributing to the high catalytic performance in simultaneous removal of NO{sub x} and soot.

  19. Multi-Column Experimental Test Bed for Xe/Kr Separation

    International Nuclear Information System (INIS)

    Greenhalgh, Mitchell Randy; Garn, Troy Gerry; Welty, Amy Keil; Lyon, Kevin Lawrence; Watson, Tony Leroy

    2015-01-01

    tests. The effluent from the AgZ-PAN column was monitored via GC-TCD during the tests with no xenon being observed exiting the column during either test. Samples from each column were taken via evacuated sample bombs and were analyzed by GC-MS analysis. The results demonstrated the ability to separate xenon from krypton from a mixed gas feed utilizing the new multi-column system.

  20. Comparison of OMI NO2 Observations and Their Seasonal and Weekly Cycles with Ground-Based Measurements in Helsinki

    Science.gov (United States)

    Ialongo, Iolanda; Herman, Jay; Krotkov, Nick; Lamsal, Lok; Boersma, Folkert; Hovila, Jari; Tamminen, Johanna

    2016-01-01

    We present the comparison of satellite-based OMI (Ozone Monitoring Instrument) NO2 products with ground-based observations in Helsinki. OMI NO2 total columns, available from standard product (SP) and DOMINO algorithm, are compared with the measurements performed by the Pandora spectrometer in Helsinki in 2012. The relative difference between Pandora 21 and OMI SP retrievals is 4 and 6 for clear sky and all sky conditions, respectively. DOMINO NO2 retrievals showed slightly lower total columns with median differences about 5 and 14 for clear sky and all sky conditions, respectively. Large differences often correspond to cloudy autumn-winter days with solar zenith angles above 65. Nevertheless, the differences remain within the retrieval uncertainties. Furthermore, the weekly and seasonal cycles from OMI, Pandora and NO2 surface concentrations are compared. Both satellite- and ground-based data show a similar weekly cycle, with lower NO2 levels during the weekend compared to the weekdays as result of reduced emissions from traffic and industrial activities. Also the seasonal cycle shows a similar behavior, even though the results are affected by the fact that most of the data are available during spring-summer because of cloud cover in other seasons. This is one of few works in which OMI NO2 retrievals are evaluated in an urban site at high latitudes (60N). Despite the city of Helsinki having relatively small pollution sources, OMI retrievals have proved to be able to describe air quality features and variability similar to surface observations. This adds confidence in using satellite observations for air quality monitoring also at high latitudes.

  1. NO2 inhalation promotes Alzheimer’s disease-like progression: cyclooxygenase-2-derived prostaglandin E2 modulation and monoacylglycerol lipase inhibition-targeted medication

    Science.gov (United States)

    Yan, Wei; Yun, Yang; Ku, Tingting; Li, Guangke; Sang, Nan

    2016-03-01

    Air pollution has been reported to be associated with increased risks of cognitive impairment and neurodegenerative diseases. Because NO2 is a typical primary air pollutant and an important contributor to secondary aerosols, NO2-induced neuronal functional abnormalities have attracted greater attention, but the available experimental evidence, modulating mechanisms, and targeting medications remain ambiguous. In this study, we exposed C57BL/6J and APP/PS1 mice to dynamic NO2 inhalation and found for the first time that NO2 inhalation caused deterioration of spatial learning and memory, aggravated amyloid β42 (Aβ42) accumulation, and promoted pathological abnormalities and cognitive defects related to Alzheimer’s disease (AD). The microarray and bioinformation data showed that the cyclooxygenase-2 (COX-2)-mediated arachidonic acid (AA) metabolism of prostaglandin E2 (PGE2) played a key role in modulating this aggravation. Furthermore, increasing endocannabinoid 2-arachidonoylglycerol (2-AG) by inhibiting monoacylglycerol lipase (MAGL) prevented PGE2 production, neuroinflammation-associated Aβ42 accumulation, and neurodegeneration, indicating a therapeutic target for relieving cognitive impairment caused by NO2 exposure.

  2. Mass transfer model liquid phase catalytic exchange column simulation applicable to any column composition profile

    Energy Technology Data Exchange (ETDEWEB)

    Busigin, A. [NITEK USA Inc., Ocala, FL (United States)

    2015-03-15

    Liquid Phase Catalytic Exchange (LPCE) is a key technology used in water detritiation systems. Rigorous simulation of LPCE is complicated when a column may have both hydrogen and deuterium present in significant concentrations in different sections of the column. This paper presents a general mass transfer model for a homogenous packed bed LPCE column as a set of differential equations describing composition change, and equilibrium equations to define the mass transfer driving force within the column. The model is used to show the effect of deuterium buildup in the bottom of an LPCE column from non-negligible D atom fraction in the bottom feed gas to the column. These types of calculations are important in the design of CECE (Combined Electrolysis and Catalytic Exchange) water detritiation systems.

  3. Protocols for the measurement of the F2-isoprostane, 15(S)-8-iso-prostaglandin F2α, in biological samples by GC-MS or GC-MS/MS coupled with immunoaffinity column chromatography.

    Science.gov (United States)

    Tsikas, Dimitrios; Suchy, Maria-Theresia

    2016-04-15

    Arachidonic acid, the origin of the eicosanoids family, occurs in biological samples as free acid and as ester in lipids. Free arachidonic acid is oxidized to numerous metabolites by means of enzymes including cyclooxygenase (COX). Arachidonic acid esterified to lipids is attacked by reactive oxygen species (ROS) to generate numerous oxidized arachidonic acid derivatives. Generally, it is assumed that ROS-derived arachidonic acid derivatives are distinct from those generated by enzymes such as COX. Therefore, ROS-generated eicosanoids are considered specific biomarkers of oxidative stress. However, there are serious doubts concerning a strict distinction between the enzyme-derived eicosanoids and the ROS-derived iso-eicosanoids. Prominent examples are prostaglandin F2α (PGF2α) and 15(S)-8-iso-prostaglandin F2α (15(S)-8-iso-PGF2α) which have been originally considered to exclusively derive from COX and ROS, respectively. There is convincing evidence that both COX and ROS can oxidize arachidonic acid to PGF2α and 15(S)-8-iso-PGF2α. Thus, many results previously reported for 15(S)-8-iso-PGF2α as exclusive ROS-dependent reaction product, and consequently as a specific biomarker of oxidative stress, require a careful re-examination which should also consider the analytical methods used to measure 15(S)-8-iso-PGF2α. This prominent but certainly not the only example underlines more than ever the importance of the analytical chemistry in basic and clinical research areas of oxidative stress. In the present work, we report analytical protocols for the reliable quantitative determination of 15(S)-8-iso-PGF2α in human biological samples including plasma and urine by mass spectrometry coupled to gas chromatography (GC-MS, GC-MS/MS) after specific isolation of endogenous 15(S)-8-iso-PGF2α and the externally added internal standard [3,3',4,4'-(2)H4]-15(S)-8-iso-PGF2α by immunoaffinity column chromatography (IAC). 15(S)-8-iso-PGF2α esterified to plasma lipids is

  4. Liquid chromatographic determination of microcystins in water samples following pre-column excimer fluorescence derivatization with 4-(1-pyrene)butanoic acid hydrazide.

    Science.gov (United States)

    Hayama, Tadashi; Katoh, Kenji; Aoki, Takayoshi; Itoyama, Miki; Todoroki, Kenichiro; Yoshida, Hideyuki; Yamaguchi, Masatoshi; Nohta, Hitoshi

    2012-11-28

    A method to measure the concentrations of microcystins (MCs) in water samples has been developed by incorporating pre-column fluorescence derivatization and liquid chromatography (LC). A solid-phase extraction for pretreatment was used to extract the MCs in water samples. The MCs were derivatized with excimer-forming 4-(1-pyrene)butanoic acid hydrazide (PBH). The MCs could then be detected by fluorescence after separation with a pentafluorophenyl (PFP)-modified superficially porous (core shell) particle LC column. The derivatization reactions of MCs with PBH proceeded easily in the presence of 4,6-dimethoxy-1,3,5-triazin-2-yl-4-methylmorpholinium (DMT-MM) as a condensation reagent, and the resulting derivatives could be easily separated on the PFP column. The derivatives were selectively detected at excimer fluorescence wavelengths (440-540 nm). The instrument detection limit and the instrument quantification limit of the MCs standards were 0.4-1.2 μg L(-1) and 1.4-3.9 μg L(-1), respectively. The method was validated at 0.1 and 1.0 μg L(-1) levels in tap and pond water samples, and the recovery of MCs was between 67 and 101% with a relative standard deviation of 11%. The proposed method can be used to quantify trace amounts of MCs in water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Experimental engineering section off-gas decontamination facility's fractionator column: installation and performance

    International Nuclear Information System (INIS)

    Gilliam, T.M.; Fowler, V.L.; Inman, D.J.

    1978-03-01

    A detailed description of the third column recently installed in the Experimental Engineering Section Off-Gas Decontamination Facility (EES-ODF) is presented. The EES-ODF is being used to provide engineering-scale experiments (nominal gas and liquid flows of 5 scfm and 0.5 gpm, respectively) in the development of the Krypton Absorption in Liquid CO 2 (KALC) process. A detailed discussion of the column's construction is provided. This discussion includes the peripherals associated with the column, such as refrigeration, heat exchangers, instrumentation, etc. The compressibility of Goodloe packing (the packing in the other columns) and the possible reduced throughput due to this compression have revealed the desirablility of a random (i.e., noncompressible) packing. Toward this end, the third column is packed with a new random packing (PRO-PAK). A preliminary comparison between this packing and the woven wire mesh packing (Goodloe) used in the other two columns has been made. Experiments comparing the throughput capacity indicate that the PRO-PAK packing has approximately 60% the capacity of Goodloe for a CO 2 system. When used as a fractionator or stripper with the basic O 2 -Kr-CO 2 KALC system, the PRO-PAK column produced HTU values less than or equal to the GOODLOE columns under similar operating conditions

  6. MAX-DOAS tropospheric nitrogen dioxide column measurements compared with the Lotos-Euros air quality model

    NARCIS (Netherlands)

    Vlemmix, T.; Eskes, H.J.; Piters, A.J.M.; Schaap, M.; Sauter, F.J.; Kelder, H.; Levelt, P.F.

    2015-01-01

    A 14-month data set of MAX-DOAS (Multi-Axis Differential Optical Absorption Spectroscopy) tropospheric NO2 column observations in De Bilt, the Netherlands, has been compared with the regional air quality model Lotos-Euros. The model was run on a 7×7 km2 grid, the same resolution as the emission

  7. Global observations of BrO in the troposphere using GOME-2 satellite data

    Science.gov (United States)

    Theys, N.; van Roozendael, M.; Hendrick, F.; Xin, Y.; Isabelle, D.; Richter, A.; Mathias, B.; Quentin, E.; Johnston, P. V.; Kreher, K.; Martine, D.

    2010-12-01

    Measurements from the GOME-2 satellite instrument have been analyzed for tropospheric BrO using a residual technique that combines measured BrO columns and estimates of the stratospheric BrO content from a climatological approach driven by O3 and NO2 observations. Comparisons between the GOME-2 results and correlative data including ground-based BrO vertical columns and total BrO columns derived from SCIAMACHY nadir observations, present a good level of consistency. We show that the adopted technique enables to separate the stratospheric and tropospheric fractions of the measured total BrO columns and allows studying the BrO plumes in polar region in more detail. While several satellite BrO plumes can largely be explained by an influence of stratospheric descending air, we show that numerous tropospheric BrO hotspots are associated to regions with low tropopause heights as well. Elaborating on simulations using the p-TOMCAT tropospheric chemical transport model, this finding is found to be consistent with the mechanism of bromine release through sea salt aerosols production during blowing snow events. Outside the polar region, evidences are provided for a global tropospheric BrO background with columns of 1-3 x 1013 molec/cm2.

  8. Reactivity in the removal of SO{sub 2} and NO{sub x} on Co/Mg/Al mixed oxides derived from hydrotalcites

    Energy Technology Data Exchange (ETDEWEB)

    Palomares, A.E. [Department of Chemical and Nuclear Engineering, Universidad Politecnica Valencia, Avda. de los Naranjos s/n, 46022 Valencia (Spain); Lopez-Nieto, J.M.; Corma, A. [Instituto de Tecnologia Quimica, UPV-CSIC, Universidad Politecnica de Valencia, Avenida de los Naranjos s/n., 46022 Valencia (Spain); Lazaro, F.J.; Lopez, A. [Instituto Ciencia de Materiales de Aragon (CSIC- Universidad de Zaragoza), 50015 Zaragoza (Spain)

    1999-04-05

    Metal containing hydrotalcites, where metal oxides present redox properties and hydrotalcite shows a basic character, appear to be new important environmental catalysts for the removal of SO{sub x} and NO{sub x}. Redox and basic properties of a mixed Co/Mg/Al oxide derived from hydrotalcites are tuned in order to achieve the optimal catalytic behavior required. This sample has been characterized showing that cobalt is present in two forms, as isolated and well dispersed paramagnetic ions, and as very small Co-containing particles (in the nanometric range), with an internal antiferromagnetic ordering at low temperature. The redox properties of cobalt allow the reduction of NO with propane at high temperatures and in presence of oxygen. The reduced cobalt species are proposed as the active sites. Nevertheless, for the removal of SO{sub 2} and contrary to the case of Cu/Mg/Al samples, the addition of an oxidant as cerium oxide on Co/Mg/Al is necessary in order to oxidize SO{sub 2} to SO{sub 3}. In this case, similar results than those obtained with previously reported catalyst, i.e. cerium or copper-cerium hydrotalcite, are obtained. These results indicate that this catalyst could be an adequate material for the simultaneous removal of SO{sub 2} and NO{sub x} in a FCC unit

  9. A Broad Bank Lidar for Precise Atmospheric CO2 Column Absorption Measurement from Space

    Science.gov (United States)

    Georgieva, E. M.; Heaps, W. S.; Huang, W.

    2010-01-01

    Accurate global measurement of carbon dioxide column with the aim of discovering and quantifying unknown sources and sinks has been a high priority for the last decade. In order to uncover the "missing sink" that is responsible for the large discrepancies in the budget the critical precision for a measurement from space needs to be on the order of 1 ppm. To better understand the CO2 budget and to evaluate its impact on global warming the National Research Council (NRC) in its recent decadal survey report (NACP) to NASA recommended a laser based total CO2 mapping mission in the near future. That's the goal of Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS) mission - to significantly enhance the understanding of the role of CO2 in the global carbon cycle. Our current goal is to develop an ultra precise, inexpensive new lidar system for column measurements of CO2 changes in the lower atmosphere that uses a Fabry-Perot interferometer based system as the detector portion of the instrument and replaces the narrow band laser commonly used in lidars with a high power broadband source. This approach reduces the number of individual lasers used in the system and considerably reduces the risk of failure. It also tremendously reduces the requirement for wavelength stability in the source putting this responsibility instead on the Fabry- Perot subsystem.

  10. Inverse modeling of GOSAT-retrieved ratios of total column CH4 and CO2 for 2009 and 2010

    Directory of Open Access Journals (Sweden)

    S. Pandey

    2016-04-01

    Full Text Available This study investigates the constraint provided by greenhouse gas measurements from space on surface fluxes. Imperfect knowledge of the light path through the atmosphere, arising from scattering by clouds and aerosols, can create biases in column measurements retrieved from space. To minimize the impact of such biases, ratios of total column retrieved CH4 and CO2 (Xratio have been used. We apply the ratio inversion method described in Pandey et al. (2015 to retrievals from the Greenhouse Gases Observing SATellite (GOSAT. The ratio inversion method uses the measured Xratio as a weak constraint on CO2 fluxes. In contrast, the more common approach of inverting proxy CH4 retrievals (Frankenberg et al., 2005 prescribes atmospheric CO2 fields and optimizes only CH4 fluxes. The TM5–4DVAR (Tracer Transport Model version 5–variational data assimilation system inverse modeling system is used to simultaneously optimize the fluxes of CH4 and CO2 for 2009 and 2010. The results are compared to proxy inversions using model-derived CO2 mixing ratios (XCO2model from CarbonTracker and the Monitoring Atmospheric Composition and Climate (MACC Reanalysis CO2 product. The performance of the inverse models is evaluated using measurements from three aircraft measurement projects. Xratio and XCO2model are compared with TCCON retrievals to quantify the relative importance of errors in these components of the proxy XCH4 retrieval (XCH4proxy. We find that the retrieval errors in Xratio (mean  =  0.61 % are generally larger than the errors in XCO2model (mean  =  0.24 and 0.01 % for CarbonTracker and MACC, respectively. On the annual timescale, the CH4 fluxes from the different satellite inversions are generally in agreement with each other, suggesting that errors in XCO2model do not limit the overall accuracy of the CH4 flux estimates. On the seasonal timescale, however, larger differences are found due to uncertainties in XCO2model, particularly

  11. Sol-gel open tubular ODS columns with reversed electroosmotic flow for capillary electrochromatography.

    Science.gov (United States)

    Hayes, J D; Malik, A

    2001-03-01

    Sol-gel chemistry was successfully used for the fabrication of open tubular columns with surface-bonded octadecylsilane (ODS) stationary-phase coating for capillary electrochromatography (OT-CEC). Following column preparations, a series of experiments were performed to investigate the performance of the sol-gel coated ODS columns in OT-CEC. The incorporation of N-octadecyldimethyl[3-(trimethoxysilyl)propyl]ammonium chloride as one of the sol-gel precursors played an important role in the electrochromatographic performance of the prepared columns. This chemical reagent possesses a chromatographically favorable, bonded ODS moiety, in conjunction with three methoxy groups allowing for sol-gel reactivity. In addition, a positively charged nitrogen atom is present in the molecular structure of this reagent and provides a positively charged capillary surface responsible for the reversed electroosmotic flow (EOF) in the columns during CEC operation. Comparative studies involving the EOF within such sol-gel ODS coated and uncoated capillaries were performed using acetonitrile and methanol as the organic modifiers in the mobile phase. The use of a deactivating reagent, phenyldimethylsilane, in the sol-gel solution was evaluated. Efficiency values of over 400,000 theoretical plates per meter were achieved in CEC on a 64 cm x 25 microm i.d. sol-gel ODS open tubular column. Test mixtures of polycyclic aromatic hydrocarbons, benzene derivatives, and aromatic aldehydes and ketones were used to evaluate the CEC performances of both nondeactivated and deactivated open tubular sol-gel columns. The effects of mobile-phase organic modifier contents and pH on EOF in such columns were evaluated. The prepared sol-gel ODS columns are characterized by switchable electroosmotic flow. A pH value of approximately 8.5 was found correspond to the isoelectric point for the prepared sol-gel ODS coatings.

  12. Effect of dissolved organic matter derived from waste amendments on the mobility of inorganic arsenic (III) in the Egyptian alluvial soil

    Energy Technology Data Exchange (ETDEWEB)

    Rashad, Mohamed [Land and Water Technologies Department, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab, 21934 Alexandria (Egypt); Assaad, Faiz F. [Soils and Water Use Department, National Research Centre, Dokki, Cairo (Egypt); Shalaby, Elsayed A. [Environmental Studies Department, Institute of Graduate Studies and Research, Alexandria University (Egypt)

    2013-07-01

    Dissolved organic matter (DOM) is one of the decisive factors affecting pollutants mobility in soils receiving waste amendments. The aim of this study was to investigate the effects of DOM1 derived from agricultural solid waste (ASW) and DOM2 derived from municipal solid waste (MSW) on the mobility of inorganic arsenic (As) in two alluvial soils from the Nile River Delta. In column experiments, addition of DOM solutions significantly increased As concentration in the effluents. There was no significant difference between the two soils, the obtained results from soil2 columns revealed that DOM2 has stronger capability than DOM1 to facilitate As mobility. The pH of the studied soils is alkaline (8.1) which promoted the dissociation as well as deprotonation of DOM and as a consequence, humic substances in DOM become negatively charged organic anions, leading to their substantial competition with As for the adsorption sites on both soil surfaces. The results emphasized that in alkaline soils there is a risk of groundwater pollution in the long run by arsenic either naturally found in soil or originated at high soil pH when dissolved organic carbon (DOC) released from various organic amendments ASW and/or MSW and leached through soil profile.

  13. Variations in Microbial Community Structure through the Stratified Water Column in the Tyrrhenian Sea (Central Mediterranean

    Directory of Open Access Journals (Sweden)

    Francesco Smedile

    2015-08-01

    Full Text Available The central Mediterranean Sea is among the most oligotrophic habitats in the marine environment. In this study, we investigated the abundance, diversity and activity of prokaryoplankton in the water column (25–3000-m depth at Station Vector (Tyrrhenian Sea, 39°32.050′ N; 13°22.280′ E. This specific water column consists of three different water masses (Modified Atlantic Water (MAW, Levantine Intermediate Water (LIW and Tyrrhenian Deep Water (TDW, possessing a typical stratification of the Central Mediterranean basin. CARD-FISH showed that the metabolically-active fraction of bacterial populations exceeded the archaeal fraction along the whole water column, except at the deepest water masses. 16S rDNA and 16S rRNA clone libraries obtained from each type of water mass were used to analyse the prokaryoplankton community structure and to distinguish between active and “less active” microbial fractions. Our results showed that the rRNA-derived bacterial libraries seemed to be more depth specific compared to 16S rDNA-derived counterparts. Major differences were detected between the active fractions of bacterioplankton thriving in photic (25 m, MAW and aphotic layers (500–3000 m, LIW and TDW respectively, whereas no statistically-significant differences were detected within the deep, aphotic layers (500–3000 m, LIW and TDW. Archaeal communities possessed more depth-specific distribution patterns with both total and active fractions showing depth stratification. Cyanobacteria and Marine Group II MAGII of Euryarchaea dominated the MAW prokaryoplankton. A notable fraction of Geitlerinema-related cyanobacteria was detected among the metabolically-active bacterial population recovered from the mesopelagic (500 m, LIW aphotic layer, which is indicative of their mixotrophic behaviour. Heterotrophic Gammaproteobacteria and members of Marine Group 1.1a and the PSL12-related ALOHA group of Thaumarchaeota were both abundant in the aphotic layers

  14. Radial heterogeneity of some analytical columns used in high-performance liquid chromatography.

    Science.gov (United States)

    Abia, Jude A; Mriziq, Khaled S; Guiochon, Georges A

    2009-04-10

    An on-column electrochemical microdetector was used to determine accurately the radial distribution of the mobile phase velocity and of the column efficiency at the exit of three common analytical columns, namely a 100 mm x 4.6mm C18 bonded silica-based monolithic column, a 150 mm x 4.6mm column packed with 2.7 microm porous shell particles of C18 bonded silica (HALO), and a 150 mm x 4.6mm column packed with 3 microm fully porous C18 bonded silica particles (LUNA). The results obtained demonstrate that all three columns are not radially homogeneous. In all three cases, the efficiency was found to be lower in the wall region of the column than in its core region (the central core with a radius of 1/3 the column inner radius). The decrease in local efficiency from the core to the wall regions was lower in the case of the monolith (ca. 25%) than in that of the two particle-packed columns (ca. 35-50%). The mobile phase velocity was found to be ca. 1.5% higher in the wall than in the core region of the monolithic column while, in contrast, it was ca. 2.5-4.0% lower in the wall region for the two particle-packed columns.

  15. Study of column construction and tritium inventory of cryogenic distillation columns for tritium plant of a fusion reactor

    International Nuclear Information System (INIS)

    Iwai, Yasunori; Yamanishi, Toshihiko; Okuno, Kenji

    1996-11-01

    Cryogenic distillation column system is believed to be best for large throughput of hydrogen isotope separation. The major disadvantage of the system is a large tritium inventory in liquid phase. From a viewpoint of safety of a fusion reactor, it is important to establish the design method of minimized the tritium inventory. Anumerical study to investigate the possible design improvement to reduce inventory while maintaining separation performance was conducted. The design conditions are based on ITER DDD report, and details are as follows, 1) Exhaust stream with less than 50 Ci/y loss of tritium, 2) 99.9% purity D2, and 3) 90% purity T2. 4) total inventory with less than 100g. In the design of ITER to process 32 mol/hr, 4 columns (3 of 4 columns make closed loop) are best and total inventory is 94g. Particularly recent design of ITER to process 320 mol/hr requires additional efforts to minimize the inventory. The simulation also suggests it is effective to reduce inventory to draw two different purity product streams. (author)

  16. FULL-PHYSICS INVERSE LEARNING MACHINE FOR SATELLITE REMOTE SENSING OF OZONE PROFILE SHAPES AND TROPOSPHERIC COLUMNS

    Directory of Open Access Journals (Sweden)

    J. Xu

    2018-04-01

    Full Text Available Characterizing vertical distributions of ozone from nadir-viewing satellite measurements is known to be challenging, particularly the ozone information in the troposphere. A novel retrieval algorithm called Full-Physics Inverse Learning Machine (FP-ILM, has been developed at DLR in order to estimate ozone profile shapes based on machine learning techniques. In contrast to traditional inversion methods, the FP-ILM algorithm formulates the profile shape retrieval as a classification problem. Its implementation comprises a training phase to derive an inverse function from synthetic measurements, and an operational phase in which the inverse function is applied to real measurements. This paper extends the ability of the FP-ILM retrieval to derive tropospheric ozone columns from GOME- 2 measurements. Results of total and tropical tropospheric ozone columns are compared with the ones using the official GOME Data Processing (GDP product and the convective-cloud-differential (CCD method, respectively. Furthermore, the FP-ILM framework will be used for the near-real-time processing of the new European Sentinel sensors with their unprecedented spectral and spatial resolution and corresponding large increases in the amount of data.

  17. Vertebral Column Resection for Rigid Spinal Deformity.

    Science.gov (United States)

    Saifi, Comron; Laratta, Joseph L; Petridis, Petros; Shillingford, Jamal N; Lehman, Ronald A; Lenke, Lawrence G

    2017-05-01

    Broad narrative review. To review the evolution, operative technique, outcomes, and complications associated with posterior vertebral column resection. A literature review of posterior vertebral column resection was performed. The authors' surgical technique is outlined in detail. The authors' experience and the literature regarding vertebral column resection are discussed at length. Treatment of severe, rigid coronal and/or sagittal malalignment with posterior vertebral column resection results in approximately 50-70% correction depending on the type of deformity. Surgical site infection rates range from 2.9% to 9.7%. Transient and permanent neurologic injury rates range from 0% to 13.8% and 0% to 6.3%, respectively. Although there are significant variations in EBL throughout the literature, it can be minimized by utilizing tranexamic acid intraoperatively. The ability to correct a rigid deformity in the spine relies on osteotomies. Each osteotomy is associated with a particular magnitude of correction at a single level. Posterior vertebral column resection is the most powerful posterior osteotomy method providing a successful correction of fixed complex deformities. Despite meticulous surgical technique and precision, this robust osteotomy technique can be associated with significant morbidity even in the most experienced hands.

  18. Insights into Tikhonov regularization: application to trace gas column retrieval and the efficient calculation of total column averaging kernels

    Directory of Open Access Journals (Sweden)

    T. Borsdorff

    2014-02-01

    Full Text Available Insights are given into Tikhonov regularization and its application to the retrieval of vertical column densities of atmospheric trace gases from remote sensing measurements. The study builds upon the equivalence of the least-squares profile-scaling approach and Tikhonov regularization method of the first kind with an infinite regularization strength. Here, the vertical profile is expressed relative to a reference profile. On the basis of this, we propose a new algorithm as an extension of the least-squares profile scaling which permits the calculation of total column averaging kernels on arbitrary vertical grids using an analytic expression. Moreover, we discuss the effective null space of the retrieval, which comprises those parts of a vertical trace gas distribution which cannot be inferred from the measurements. Numerically the algorithm can be implemented in a robust and efficient manner. In particular for operational data processing with challenging demands on processing time, the proposed inversion method in combination with highly efficient forward models is an asset. For demonstration purposes, we apply the algorithm to CO column retrieval from simulated measurements in the 2.3 μm spectral region and to O3 column retrieval from the UV. These represent ideal measurements of a series of spaceborne spectrometers such as SCIAMACHY, TROPOMI, GOME, and GOME-2. For both spectral ranges, we consider clear-sky and cloudy scenes where clouds are modelled as an elevated Lambertian surface. Here, the smoothing error for the clear-sky and cloudy atmosphere is significant and reaches several percent, depending on the reference profile which is used for scaling. This underlines the importance of the column averaging kernel for a proper interpretation of retrieved column densities. Furthermore, we show that the smoothing due to regularization can be underestimated by calculating the column averaging kernel on a too coarse vertical grid. For both

  19. Modeling of intensity-modulated continuous-wave laser absorption spectrometer systems for atmospheric CO(2) column measurements.

    Science.gov (United States)

    Lin, Bing; Ismail, Syed; Wallace Harrison, F; Browell, Edward V; Nehrir, Amin R; Dobler, Jeremy; Moore, Berrien; Refaat, Tamer; Kooi, Susan A

    2013-10-10

    The focus of this study is to model and validate the performance of intensity-modulated continuous-wave (IM-CW) CO(2) laser absorption spectrometer (LAS) systems and their CO(2) column measurements from airborne and satellite platforms. The model accounts for all fundamental physics of the instruments and their related CO(2) measurement environments, and the modeling results are presented statistically from simulation ensembles that include noise sources and uncertainties related to the LAS instruments and the measurement environments. The characteristics of simulated LAS systems are based on existing technologies and their implementation in existing systems. The modeled instruments are specifically assumed to be IM-CW LAS systems such as the Exelis' airborne multifunctional fiber laser lidar (MFLL) operating in the 1.57 μm CO(2) absorption band. Atmospheric effects due to variations in CO(2), solar radiation, and thin clouds, are also included in the model. Model results are shown to agree well with LAS atmospheric CO(2) measurement performance. For example, the relative bias errors of both MFLL simulated and measured CO(2) differential optical depths were found to agree to within a few tenths of a percent when compared to the in situ observations from the flight of 3 August 2011 over Railroad Valley (RRV), Nevada, during the summer 2011 flight campaign. In addition, the horizontal variations in the model CO(2) differential optical depths were also found to be consistent with those from MFLL measurements. In general, the modeled and measured signal-to-noise ratios (SNRs) of the CO(2) column differential optical depths (τd) agreed to within about 30%. Model simulations of a spaceborne IM-CW LAS system in a 390 km dawn/dusk orbit for CO(2) column measurements showed that with a total of 42 W of transmitted power for one offline and two different sideline channels (placed at different locations on the side of the CO(2) absorption line), the accuracy of the

  20. Holdup of O/W emulsion in a packed column for liquid membrane separation of hydrocarbon; Tankasuiso no ekimaku bunri ni okeru jutento nai no emarushon horudo appu

    Energy Technology Data Exchange (ETDEWEB)

    Egashira, R.; Sugimoto, T.; Kawasaki, J. [Tokyo Inst. of Technology, Tokyo (Japan). Faculty of Engineering

    1993-07-10

    Liquid membrane separation of hydrocarbon is an energy saving separation method that is expected of practical use. If the method uses a packed column, the holdup of O/W emulsion affects the effective contact area and residence time of the emulsion. Therefore, this paper describes an attempt to correlate the dynamic emulsion holdup in a packed column in liquid membrane separation of hydrocarbon with property values of the emulsion and external oil phase, and operation variables. The experiment used a mixture of toluene + n - heptane + n - decane for oil phase in the O/W emulsion and saponin aqueous solution for liquid phase (liquid membrane phase). The packed column with an inner diameter of 37 mm used stainless steel McMahon packing. As a result of the experiment, the dynamic emulsion holdup showed a correlation according to the Reynolds number and Galilei number, regardless of whether the emulsion permeates the liquid membrane. The correlation made it possible to estimate in a simple manner the emulsion holdup in the packed column when this separation method is used. 5 refs., 3 figs., 3 tabs.

  1. The Design and Analysis of Split Row-Column Addressing Array for 2-D Transducer

    Directory of Open Access Journals (Sweden)

    Xu Li

    2016-09-01

    Full Text Available For 3-D ultrasound imaging, the row-column addressing (RCA with 2N connections for an N × N 2-D array makes the fabrication and interconnection simpler than the fully addressing with N2 connections. However, RCA degrades the image quality because of defocusing in signal channel direction in the transmit event. To solve this problem, a split row-column addressing scheme (SRCA is proposed in this paper. Rather than connecting all the elements in the signal channel direction together, this scheme divides the elements in the signal channel direction into several disconnected blocks, thus enables focusing beam access in both signal channel and switch channel directions. Selecting an appropriate split scheme is the key for SRCA to maintaining a reasonable tradeoff between the image quality and the number of connections. Various split schemes for a 32 × 32 array are fully investigated with point spread function (PSF analysis and imaging simulation. The result shows the split scheme with five blocks (4, 6, 12, 6, and 4 elements of each block can provide similar image quality to fully addressing. The splitting schemes for different array sizes from 16 × 16 to 96 × 96 are also discussed.

  2. SO2 plume height retrieval from direct fitting of GOME-2 backscattered radiance measurements

    Science.gov (United States)

    van Gent, J.; Spurr, R.; Theys, N.; Lerot, C.; Brenot, H.; Van Roozendael, M.

    2012-04-01

    The use of satellite measurements for SO2 monitoring has become an important aspect in the support of aviation control. Satellite measurements are sometimes the only information available on SO2 concentrations from volcanic eruption events. The detection of SO2 can furthermore serve as a proxy for the presence of volcanic ash that poses a possible hazard to air traffic. In that respect, knowledge of both the total vertical column amount and the effective altitude of the volcanic SO2 plume is valuable information to air traffic control. The Belgian Institute for Space Aeronomy (BIRA-IASB) hosts the ESA-funded Support to Aviation Control Service (SACS). This system provides Volcanic Ash Advisory Centers (VAACs) worldwide with near real-time SO2 and volcanic ash data, derived from measurements from space. We present results from our algorithm for the simultaneous retrieval of total vertical columns of O3 and SO2 and effective SO2 plume height from GOME-2 backscattered radiance measurements. The algorithm is an extension to the GODFIT direct fitting algorithm, initially developed at BIRA-IASB for the derivation of improved total ozone columns from satellite data. The algorithm uses parameterized vertical SO2 profiles which allow for the derivation of the peak height of the SO2 plume, along with the trace gas total column amounts. To illustrate the applicability of the method, we present three case studies on recent volcanic eruptions: Merapi (2010), Grímsvotn (2011), and Nabro (2011). The derived SO2 plume altitude values are validated with the trajectory model FLEXPART and with aerosol altitude estimations from the CALIOP instrument on-board the NASA A-train CALIPSO platform. We find that the effective plume height can be obtained with a precision as fine as 1 km for moderate and strong volcanic events. Since this is valuable information for air traffic, we aim at incorporating the plume height information in the SACS system.

  3. The role of the notochord in amniote vertebral column segmentation.

    Science.gov (United States)

    Ward, Lizzy; Pang, Angel S W; Evans, Susan E; Stern, Claudio D

    2018-07-01

    The vertebral column is segmented, comprising an alternating series of vertebrae and intervertebral discs along the head-tail axis. The vertebrae and outer portion (annulus fibrosus) of the disc are derived from the sclerotome part of the somites, whereas the inner nucleus pulposus of the disc is derived from the notochord. Here we investigate the role of the notochord in vertebral patterning through a series of microsurgical experiments in chick embryos. Ablation of the notochord causes loss of segmentation of vertebral bodies and discs. However, the notochord cannot segment in the absence of the surrounding sclerotome. To test whether the notochord dictates sclerotome segmentation, we grafted an ectopic notochord. We find that the intrinsic segmentation of the sclerotome is dominant over any segmental information the notochord may possess, and no evidence that the chick notochord is intrinsically segmented. We propose that the segmental pattern of vertebral bodies and discs in chick is dictated by the sclerotome, which first signals to the notochord to ensure that the nucleus pulposus develops in register with the somite-derived annulus fibrosus. Later, the notochord is required for maintenance of sclerotome segmentation as the mature vertebral bodies and intervertebral discs form. These results highlight differences in vertebral development between amniotes and teleosts including zebrafish, where the notochord dictates the segmental pattern. The relative importance of the sclerotome and notochord in vertebral patterning has changed significantly during evolution. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  4. Mass spectrometric determination of partial electron impact ionization cross sections of No, No2, and N2O from threshold up to 180 eV

    International Nuclear Information System (INIS)

    Kim, Y. B.

    1982-01-01

    Electron impact ionization of nitric oxide (NO), nitrogen dioxide (NO 2 ) and nitrous oxide (N 2 O) has been studied as a function of electron energy up to 180 eV with a double focussing mass spectrometer Varian MAT CH5 and an improved Nier type electron impact ion source. Relative partial ionization cross sections were measured for the processes NO + + 2e, NO ++ + 3e, and NO 2 + e -> NO + 2 + 2e, NO ++ + 3e and N 2 O + e -> N 2 O + + 2e. An accurate measurement of the cross section ratios q(NO 2+ /NO)/q(NO + /NO) and q(NO 2 2 /NO 2 )/q(NO + 2 /NO 2 ) has been made. Relative cross section functions were calibrated absolutely with two different normalization methods. Moreover, both metastable and collision induced dissociations of N 2 O + were studied quantitatively using the technique of decoupling the acceleration and deflection electric fields. Using the n- th root extrapolation the following ionization potentials have been derived from the cross section functions near threshold: NO + (X 1 Σ + ); NO ++ ; NO + 2 ; NO 2 ++ ; N 2 O + (X 2 π). These results are compared with previous measurements and theoretical calculations, where available. Part of the results presented have been already published in seven papers by the author. (Author)

  5. Nitrogen dioxide column content measurements made from an aircraft between 5 deg and 82 deg N

    Energy Technology Data Exchange (ETDEWEB)

    Matthews, W A

    1984-01-01

    In the first two weeks of May 1981, the research jet of the German Aerospace Research Estlablishment (DFVLR) was charted to fly a meridional section between 5 deg and 82 deg N. A scanning filter photometer, developed at the Max-Planck-Institut fuer Aeronomie to measure column content values of atmospheric ozone and nitrogen dioxide, using ultraviolet and visible absorption techniques, constituted part of the experimental payload for this campaign that was called SIMOC. The vertical NO2 column content above the aircraft, flying at approximately 10 km, was found to decrease rapidly from 6.9 x 10 to the 15th molecules/sq cm to 2.5 x 10 to the 15th molecules/sq cm around 50 deg N and then to increase again north of 75 deg N. A sharp rise in the NO2 content was observed south of the subtropical jet but this could possibly be due to the increased depth of the troposphere above the aircraft in these regions. 8 references.

  6. Applicability of hydroxylamine nitrate reductant in pulse-column contactors

    International Nuclear Information System (INIS)

    Reif, D.J.

    1983-05-01

    Uranium and plutonium separations were made from simulated breeder reactor spent fuel dissolver solution with laboratory-sized pulse column contactors. Hydroxylamine nitrate (HAN) was used for reduction of plutonium (1V). An integrated extraction-partition system, simulating a breeder fuel reprocessing flowsheet, carried out a partial partition of uranium and plutonium in the second contactor. Tests have shown that acceptable coprocessing can be ontained using HAN as a plutonium reductant. Pulse column performance was stable even though gaseous HAN oxidation products were present in the column. Gas evolution rates up to 0.27 cfm/ft 2 of column cross section were tested and found acceptable

  7. Dopamine-imprinted monolithic column for capillary electrochromatography.

    Science.gov (United States)

    Aşır, Süleyman; Sarı, Duygu; Derazshamshir, Ali; Yılmaz, Fatma; Şarkaya, Koray; Denizli, Adil

    2017-11-01

    A dopamine-imprinted monolithic column was prepared and used in capillary electrochromatography as stationary phase for the first time. Dopamine was selectively separated from aqueous solution containing the competitor molecule norepinephrine, which is similar in size and shape to the template molecule. Morphology of the dopamine-imprinted column was observed by scanning electron microscopy. The influence of the organic solvent content of mobile phase, applied pressure and pH of the mobile phase on the recognition of dopamine by the imprinted monolithic column has been evaluated, and the imprinting effect in the dopamine-imprinted monolithic polymer was verified. Developed dopamine-imprinted monolithic column resulted in excellent separation of dopamine from structurally related competitor molecule, norepinephrine. Separation was achieved in a short period of 10 min, with the electrophoretic mobility of 5.81 × 10 -5  m 2 V -1 s -1 at pH 5.0 and 500 mbar pressure. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Diversity of active aerobic methanotrophs along depth profiles of arctic and subarctic lake water column and sediments

    Science.gov (United States)

    He, Ruo; Wooller, Matthew J.; Pohlman, John W.; Quensen, John; Tiedje, James M.; Leigh, Mary Beth

    2012-01-01

    Methane (CH4) emitted from high-latitude lakes accounts for 2–6% of the global atmospheric CH4 budget. Methanotrophs in lake sediments and water columns mitigate the amount of CH4 that enters the atmosphere, yet their identity and activity in arctic and subarctic lakes are poorly understood. We used stable isotope probing (SIP), quantitative PCR (Q-PCR), pyrosequencing and enrichment cultures to determine the identity and diversity of active aerobic methanotrophs in the water columns and sediments (0–25 cm) from an arctic tundra lake (Lake Qalluuraq) on the north slope of Alaska and a subarctic taiga lake (Lake Killarney) in Alaska's interior. The water column CH4 oxidation potential for these shallow (~2m deep) lakes was greatest in hypoxic bottom water from the subarctic lake. The type II methanotroph, Methylocystis, was prevalent in enrichment cultures of planktonic methanotrophs from the water columns. In the sediments, type I methanotrophs (Methylobacter, Methylosoma and Methylomonas) at the sediment-water interface (0–1 cm) were most active in assimilating CH4, whereas the type I methanotroph Methylobacter and/or type II methanotroph Methylocystis contributed substantially to carbon acquisition in the deeper (15–20 cm) sediments. In addition to methanotrophs, an unexpectedly high abundance of methylotrophs also actively utilized CH4-derived carbon. This study provides new insight into the identity and activity of methanotrophs in the sediments and water from high-latitude lakes.

  9. Estimating Western U.S. Oil & Gas Emissions with OMI NO2 Data

    Science.gov (United States)

    Clifton, O. E.; Holloway, T.; Oberman, J.

    2012-12-01

    In the last ten years, there has been a steep increase in the number natural gas and oil extraction facilities in the United States due to hydraulic fracturing ("fracking"). Each facility requires a large range of equipment, such as drilling rigs, compressor engines, heaters, and pneumatic devices. These activities can lead to elevated nitrogen dioxide (NO2) emissions in rural areas, often in regions without routine NO2 surface monitoring. Furthermore, permitting rules vary from state to state, and many new extraction facilities are unpermitted and exact emissions unknown. On April 18, 2012, the EPA announced air pollution standards for volatile organic compounds (VOCs) emissions from the oil and gas industry. Until 2015, when these standards must be in effect, NOx (NO2 + NO) will continue to react with VOCs to form unhealthy levels of tropospheric ozone in regions with heavy use of hydraulic fracturing. In order to identify areas of elevated NO2 emissions and constrain associated on-road and off-road sources in areas with prominent shale basins and known drilling, we employ remote sensing estimates of column NO2 from the Ozone Monitoring Instrument (OMI) aboard NASA's Aura satellite. OMI NO2 is sensitive to the planetary boundary layer and to surface air pollution and thus has high temporal and spatial variation. These Level-2 satellite data are processed with the Wisconsin Horizontal Interpolation Program for Satellites (WHIPS), developed at the University of Wisconsin-Madison. We interpolate the data to allow further ease in mapping change in NO2 associated with drilling, and the quantification of pollution trends attributable to hydraulic-fracturing in the Western U.S. from 2004 to the present.

  10. Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching

    Energy Technology Data Exchange (ETDEWEB)

    Li Kun [Department of Plant, Soil, and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States); Xing Baoshan [Department of Plant, Soil, and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States) and Northeast Institute of Geography and Agro-ecology, CAS, Harbin 150040 (China)]. E-mail: bx@pssci.umass.edu; Torello, William A. [Department of Plant, Soil, and Insect Sciences, Stockbridge Hall, University of Massachusetts, Amherst, MA 01003 (United States)

    2005-03-01

    Incorporation of organic fertilizers/amendments has been, and continues to be, a popular strategy for golf course turfgrass management. Dissolved organic matter (DOM) derived from these organic materials may, however, facilitate organic chemical movement through soils. A batch equilibrium technique was used to evaluate the effects of organic fertilizer-derived DOM on sorption of three organic chemicals (2,4-D, naphthalene and chlorpyrifos) in USGA (United States Golf Association) sand, a mixed soil (70% USGA sand and 30% native soil) and a silt loam soil (Typic Fragiochrept). DOM was extracted from two commercial organic fertilizers. Column leaching experiments were also performed using USGA sand. Sorption experiments showed that sorption capacity was significantly reduced with increasing DOM concentration in solution for all three chemicals. Column experimental results were consistent with batch equilibrium data. These results suggest that organic fertilizer-derived DOM might lead to enhanced transport of applied chemicals in turf soils. - Dissolved organic matter could result in enhanced transport of chemicals applied to turf.

  11. Effect of organic fertilizers derived dissolved organic matter on pesticide sorption and leaching

    International Nuclear Information System (INIS)

    Li Kun; Xing Baoshan; Torello, William A.

    2005-01-01

    Incorporation of organic fertilizers/amendments has been, and continues to be, a popular strategy for golf course turfgrass management. Dissolved organic matter (DOM) derived from these organic materials may, however, facilitate organic chemical movement through soils. A batch equilibrium technique was used to evaluate the effects of organic fertilizer-derived DOM on sorption of three organic chemicals (2,4-D, naphthalene and chlorpyrifos) in USGA (United States Golf Association) sand, a mixed soil (70% USGA sand and 30% native soil) and a silt loam soil (Typic Fragiochrept). DOM was extracted from two commercial organic fertilizers. Column leaching experiments were also performed using USGA sand. Sorption experiments showed that sorption capacity was significantly reduced with increasing DOM concentration in solution for all three chemicals. Column experimental results were consistent with batch equilibrium data. These results suggest that organic fertilizer-derived DOM might lead to enhanced transport of applied chemicals in turf soils. - Dissolved organic matter could result in enhanced transport of chemicals applied to turf

  12. Experimental analysis of reinforced concrete columns strengthened with Self-Compacting concrete

    Directory of Open Access Journals (Sweden)

    M. Y. M. Omar

    Full Text Available This paper presents the results of reinforced concrete columns strengthened by addition of a self-compacting concrete overlay at the compressed and at the tensioned face of the member, with and without addition of longitudinal steel bars. Eight columns were submit- ted to loading with an initial eccentricity of 60 mm . These columns had 120 mm x 250 mm of rectangular cross section, 2000 mm in length and four longitudinal reinforcement steel bars with 10 mm in diameter. Reference columns P1 and P2 were tested to failure without any type of rehabilitation. Columns P3 to P8 were loaded to a predefined load (close to the initial yield point of tension reinforce- ment, then unloaded and strengthened for a subsequent test until failure. Results showed that the method of rehabilitation used was effective, increasing the loading capacity of the strengthened pieces by 2 to 5 times the ultimate load of the reference column.

  13. Ion mobility based on column leaching of South African gold tailings dam with chemometric evaluation.

    Science.gov (United States)

    Cukrowska, Ewa M; Govender, Koovila; Viljoen, Morris

    2004-07-01

    New column leaching experiments were designed and used as an alternative rapid screening approach to element mobility assessment. In these experiments, field-moist material was treated with an extracting solution to assess the effects of acidification on element mobility in mine tailings. The main advantage of this version of column leaching experiments with partitioned segments is that they give quick information on current element mobility in conditions closely simulating field conditions to compare with common unrepresentative air-dried, sieved samples used for column leaching experiments. Layers from the tailings dump material were sampled and packed into columns. The design of columns allows extracting leachates from each layer. The extracting solutions used were natural (pH 6.8) and acidified (pH 4.2) rainwater. Metals and anions were determined in the leachates. The concentrations of metals (Ca, Mg, Fe, Mn, Al, Cr, Ni, Co, Zn, and Cu) in sample leachates were determined using ICP OES. The most important anions (NO3-, Cl-, and SO4(2)-) were determined using the closed system izotacophoresis ITP analyser. The chemical analytical data from tailings leaching and physico-chemical data from field measurements (including pH, conductivity, redox potential, temperature) were used for chemometric evaluation of element mobility. Principal factor analysis (PFA) was used to evaluate ions mobility from different layers of tailings dump arising from varied pH and redox conditions. It was found that the results from the partitioned column leaching illustrate much better complex processes of metals mobility from tailings dump than the total column. The chemometric data analysis (PFA) proofed the differences in the various layers leachability that are arising from physico-chemical processes due to chemical composition of tailings dump deposit. Copyright 2004 Elsevier Ltd.

  14. Removal of geosmin and 2-methylisoborneol during managed aquifer recharge: Batch and column studies

    KAUST Repository

    Maeng, Sungkyu

    2012-06-01

    Managed aquifer recharge is a robust barrier in the multi-barrier approach to supply safe drinking water. The removal performance of gesomin and 2-methylisoborneol through managed aquifer recharge was investigated using batch and column experiments. Batch experiments were carried out to investigate the removal of geosmin and 2-methylisoborneol (MIB) in the presence of different types of biodegradable organic matter using different types of water. Five different types of water spiked with 70-293 ng/L of geosmin and MIB were used in batch reactors, and complete removal of geosmin and MIB (down to the detection limit) was achieved in all cases. Soil column studies showed that biodegradation contributed to the removal of geosmin and MIB by 23 and 31%, respectively (empty bed contact time: 17 hours). The removal of geosmin and MIB appeared to be influenced more by microbial activity than the initial concentrations of geosmin and MIB. Adsorption was found to be the dominant mechanism (major role) followed by biodegradation (minor role) for geosmin and MIB removals during soil passage. Managed aquifer charge can therefore be used as a robust barrier to remove taste and odor (T&O) causing compounds.© IWA Publishing 2012.

  15. On the link between column density distribution and density scaling relation in star formation regions

    Science.gov (United States)

    Veltchev, Todor; Donkov, Sava; Stanchev, Orlin

    2017-07-01

    We present a method to derive the density scaling relation ∝ L^{-α} in regions of star formation or in their turbulent vicinities from straightforward binning of the column-density distribution (N-pdf). The outcome of the method is studied for three types of N-pdf: power law (7/5≤α≤5/3), lognormal (0.7≲α≲1.4) and combination of lognormals. In the last case, the method of Stanchev et al. (2015) was also applied for comparison and a very weak (or close to zero) correlation was found. We conclude that the considered `binning approach' reflects rather the local morphology of the N-pdf with no reference to the physical conditions in a considered region. The rough consistency of the derived slopes with the widely adopted Larson's (1981) value α˜1.1 is suggested to support claims that the density-size relation in molecular clouds is indeed an artifact of the observed N-pdf.

  16. A new method to detect long term trends of methane (CH4 and nitrous oxide (N2O total columns measured within the NDACC ground-based high resolution solar FTIR network

    Directory of Open Access Journals (Sweden)

    M. Schneider

    2011-07-01

    Full Text Available Total columns measured with the ground-based solar FTIR technique are highly variable in time due to atmospheric chemistry and dynamics in the atmosphere above the measurement station. In this paper, a multiple regression model with anomalies of air pressure, total columns of hydrogen fluoride (HF and carbon monoxide (CO and tropopause height are used to reduce the variability in the methane (CH4 and nitrous oxide (N2O total columns to estimate reliable linear trends with as small uncertainties as possible. The method is developed at the Harestua station (60° N, 11° E, 600 m a.s.l. and used on three other European FTIR stations, i.e. Jungfraujoch (47° N, 8° E, 3600 m a.s.l., Zugspitze (47° N, 11° E, 3000 m a.s.l., and Kiruna (68° N, 20° E, 400 m a.s.l.. Linear CH4 trends between 0.13 ± 0.01-0.25 ± 0.02 % yr−1 were estimated for all stations in the 1996-2009 period. A piecewise model with three separate linear trends, connected at change points, was used to estimate the short term fluctuations in the CH4 total columns. This model shows a growth in 1996–1999 followed by a period of steady state until 2007. From 2007 until 2009 the atmospheric CH4 amount increases between 0.57 ± 0.22–1.15 ± 0.17 % yr−1. Linear N2O trends between 0.19 ± 0.01–0.40 ± 0.02 % yr−1 were estimated for all stations in the 1996-2007 period, here with the strongest trend at Harestua and Kiruna and the lowest at the Alp stations. From the N2O total columns crude tropospheric and stratospheric partial columns were derived, indicating that the observed difference in the N2O trends between the FTIR sites is of stratospheric origin. This agrees well with the N2O measurements by the SMR instrument onboard the Odin satellite showing the highest trends at Harestua, 0.98 ± 0.28 % yr−1, and considerably smaller trends at lower latitudes, 0.27 ± 0.25 % yr−1. The multiple regression model was compared with two other trend methods, the ordinary linear

  17. Single-column ion chromatography with determination of hydrazoic acid produced in spent nuclear fuel reprocessing

    International Nuclear Information System (INIS)

    Ma Guilan; Tan Shuping

    2006-01-01

    The reaction of hydrazine and its derivative with ammonium metavanadate may produce hydrazoic acid (HN 3 ). A single-column ion chromatography is used for the determination of HN 3 after neutralizing the rest acid in the sample with sodium hydroxide. Chromatography separation of HN 3 is carried out on a 25 cm x 0.46 cm (inside diameter) stainless steel column packed with Vydac IC302 ion Chromatography packing. The eluent is 1 mmol/L o-phthalic acid, and the ion is detected by conductivity detector. The detection limit in the presence chromatography is 5 μg/mL, the linear range is from 5 to 201 μg/mL, the linear correlation coefficient is 0.9994, respectively. The analysis accuracy is 2% for standard sample, and the detection limit is 51 μg/mL for HN 3 in the real sample. (authors)

  18. Photocatalytic activity of self-assembled porous TiO2 nano-columns array fabricated by oblique angle sputter deposition

    Science.gov (United States)

    Shi, Pengjun; Li, Xibo; Zhang, Qiuju; Yi, Zao; Luo, Jiangshan

    2018-04-01

    A well-separated and oriented TiO2 nano-columns arrays with porous structure were fabricated by the oblique angle sputter deposition technique and subsequently annealing at 450 °C in Ar/O2 mixed atmosphere. The deposited substrate was firstly modified by a template of self-assembled close-packed arrays of 500 nm-diameter silica (SiO2) spheres. Scanning electronic microscopic (SEM) images show that the porous columnar nanostructure is formed as a result of the geometric shadowing effect and surface diffusion of the adatoms in oblique angle deposition (OAD). X-ray diffraction (XRD) measurements reveal that the physically OAD film with annealing treatment are generally mixed phase of rutile and anatase TiO2 polymorphic forms. The morphology induced absorbance and band gap tuning by different substrates was demonstrated by the UV–vis spectroscopy. The well-separated one-dimensional (1D) nano-columns array with specific large porous surface area is beneficial for charge separation in photocatalytic degradation. Compared with compact thin film, such self-assembled porous TiO2 nano-columns array fabricated by oblique angle sputter deposition performed an enhanced visible light induced photocatalytic activity by decomposing methyl orange (MO) solution. The well-designed periodic array-structured porous TiO2 films by using modified patterned substrates has been demonstrated significantly increased absorption edge in the UV-visible light region with a narrower optical band gap, which are expected to be favorable for application in photovoltaic, lithium-ion insertion and photocatalytic, etc.

  19. GOME-2A retrievals of tropospheric NO2 in different spectral ranges – influence of penetration depth

    Directory of Open Access Journals (Sweden)

    L. K. Behrens

    2018-05-01

    Full Text Available In this study, we present a novel nitrogen dioxide (NO2 differential optical absorption spectroscopy (DOAS retrieval in the ultraviolet (UV spectral range for observations from the Global Ozone Monitoring Instrument 2 on board EUMETSAT's MetOp-A (GOME-2A satellite. We compare the results to those from an established NO2 retrieval in the visible (vis spectral range from the same instrument and investigate how differences between the two are linked to the NO2 vertical profile shape in the troposphere.As expected, radiative transfer calculations for satellite geometries show that the sensitivity close to the ground is higher in the vis than in the UV spectral range. Consequently, NO2 slant column densities (SCDs in the vis are usually higher than in the UV if the NO2 is close to the surface. Therefore, these differences in NO2 SCDs between the two spectral ranges contain information on the vertical distribution of NO2 in the troposphere. We combine these results with radiative transfer calculations and simulated NO2 fields from the TM5-MP chemistry transport model to evaluate the simulated NO2 vertical distribution.We investigate regions representative of both anthropogenic and biomass burning NO2 pollution. Anthropogenic air pollution is mostly located in the boundary layer close to the surface, which is reflected by large differences between UV and vis SCDs of  ∼  60 %. Biomass burning NO2 in contrast is often uplifted into elevated layers above the boundary layer. This is best seen in tropical Africa south of the Equator, where the biomass burning NO2 is well observed in the UV, and the SCD difference between the two spectral ranges is only  ∼  36 %. In tropical Africa north of the Equator, however, the biomass burning NO2 is located closer to the ground, reducing its visibility in the UV.While not enabling a full retrieval of the vertical NO2 profile shape in the troposphere, our results can help to constrain the vertical

  20. Investigation of column flotation process on sulphide ore using 2-electrode capacitance sensor: The effect of air flow rate and solid percentage

    Science.gov (United States)

    Haryono, Didied; Harjanto, Sri; Wijaya, Rifky; Oediyani, Soesaptri; Nugraha, Harisma; Huda, Mahfudz Al; Taruno, Warsito Purwo

    2018-04-01

    Investigation of column flotation process on sulphide ore using 2-electrode capacitance sensor is presented in this paper. The effect of air flow rate and solid percentage on column flotation process has been experimentally investigated. The purpose of this paper is to understand the capacitance signal characteristic affected by the air flow rate and the solid percentage which can be used to determine the metallurgical performance. Experiments were performed using a laboratory column flotation cell which has a diameter of 5 cm and the total height of 140 cm. The sintered ceramic sparger and wash water were installed at the bottom and above of the column. Two-electrode concave type capacitance sensor was also installed at a distance of 50 cm from the sparger. The sensor was attached to the outer wall of the column, connected to data acquisition system, manufactured by CTECH Labs Edwar Technology and personal computer for further data processing. Feed consisting ZnS and SiO2 with the ratio of 3:2 was mixed with some reagents to make 1 litre of slurry. The slurry was fed into the aerated column at 100 cm above the sparger with a constant rate and the capacitance signals were captured during the process. In this paper, 7.5 and 10% of solid and 2-4 L/min of air flow rate with 0.5 L/min intervals were used as independent variables. The results show that the capacitance signal characteristics between the 7.5 and 10% of solid are different at any given air flow rate in which the 10% solid produced signals higher than those of 7.5%. Metallurgical performance and capacitance signal exhibit a good correlation.

  1. Behaviour of normal reinforced concrete columns exposed to different soils

    Directory of Open Access Journals (Sweden)

    Rasheed Laith

    2018-01-01

    Full Text Available Concrete resistance to sulfate attack is one of the most important characteristics for maintaining the durability of concrete. In this study, the effect of the attack of sulfate salts on normal reinforced concrete column was investigated by burying these columns in two types of soils (sandy and clayey in two pits at a depth of 3 m in one of the agricultural areas in the holy city of Karbala, one containing sandy soil (SO3 = 10.609% and the other containing clayey soil with (SO3 = 2.61%. The tests were used (pure axial compression test of reinforced concrete columns, compressive strength test, and splitting tensile strength test, absorption, voids ratio and finally density. It`s found that the strength of RC columns decreasing by (12.51% for age (240 days, for columns buried in clayey soil, where the strength increased by (11.71% for the same period, for columns buried in sandy soils, with respect to the reference column.

  2. One stacked-column vibration test and analysis for VHTR core

    International Nuclear Information System (INIS)

    Ikushima, Takeshi; Ishizuka, Hiroshi; Ide, Akira; Hayakawa, Hitoshi; Shingai, Kazuteru.

    1978-07-01

    This paper describes experimental results of the vibration test on a single stacked-column and compares them with the analytical results. A 1/2 scale model of the core element of a very high temperature gas-cooled reactor (VHTR) was set on a shaking table. Sinusoidal waves, response time history waves, beat wave and step wave of input acceleration 100 - 900 gal in the frequency of 0.5 to 15 Hz were used to vibrate the table horizontally. Results are as follows: (1) The column has a non-linear resonance and exhibits a hysteresis response with jump points. (2) The column vibration characteristics is similar to that of the finite beams connected with non-linear soft spring. (3) The column resonance frequency decreases with increasing input acceleration. (4) The impact force increases with increasing input acceleration and boundary gap width. (5) Good correlation in vibration behavior of the stacked-column and impact force on the boundary between test and analysis was obtained. (auth.)

  3. Hemifield columns co-opt ocular dominance column structure in human achiasma.

    Science.gov (United States)

    Olman, Cheryl A; Bao, Pinglei; Engel, Stephen A; Grant, Andrea N; Purington, Chris; Qiu, Cheng; Schallmo, Michael-Paul; Tjan, Bosco S

    2018-01-01

    In the absence of an optic chiasm, visual input to the right eye is represented in primary visual cortex (V1) in the right hemisphere, while visual input to the left eye activates V1 in the left hemisphere. Retinotopic mapping In V1 reveals that in each hemisphere left and right visual hemifield representations are overlaid (Hoffmann et al., 2012). To explain how overlapping hemifield representations in V1 do not impair vision, we tested the hypothesis that visual projections from nasal and temporal retina create interdigitated left and right visual hemifield representations in V1, similar to the ocular dominance columns observed in neurotypical subjects (Victor et al., 2000). We used high-resolution fMRI at 7T to measure the spatial distribution of responses to left- and right-hemifield stimulation in one achiasmic subject. T 2 -weighted 2D Spin Echo images were acquired at 0.8mm isotropic resolution. The left eye was occluded. To the right eye, a presentation of flickering checkerboards alternated between the left and right visual fields in a blocked stimulus design. The participant performed a demanding orientation-discrimination task at fixation. A general linear model was used to estimate the preference of voxels in V1 to left- and right-hemifield stimulation. The spatial distribution of voxels with significant preference for each hemifield showed interdigitated clusters which densely packed V1 in the right hemisphere. The spatial distribution of hemifield-preference voxels in the achiasmic subject was stable between two days of testing and comparable in scale to that of human ocular dominance columns. These results are the first in vivo evidence showing that visual hemifield representations interdigitate in achiasmic V1 following a similar developmental course to that of ocular dominance columns in V1 with intact optic chiasm. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Modifications of the Cornell University TRIGA reactor thermal column

    International Nuclear Information System (INIS)

    Aderhold, Howard C.

    1984-01-01

    Full text: The thermal column has been modified to provide a horizontal beam suitable for neutron radiography. A hole of circular cross-section was cut along the axis of the thermal column through graphite and lead from the outer surface of the 'sliding block' to a point about 10 cm short of the curved end of the thermal column. The section through the sliding block is 15.2 cm in diameter and the remaining section is 10.2 cm in diameter. The outer or 15.2-cm section is lined with a 6-mm thick Boral sleeve, and the inner or 10.2-cm section contains a tapered collimator of Pd-Cd alloy inside a 3-mm thick Boral sleeve, a defining aperture formed by a 2.5-cm diameter hole in a 6-mm Boral plate, and, at the core end, a 5.1-cm thick bismuth absorber disk. All of these components are enclosed in an aluminum housing. From the sliding block outwards - a distance of 122 cm across the hohlraum and through the graphite at the exit end, plus another 122 cm through the rolling door - no drilling was necessary since removable plugs could be taken out to form a tapered hole of square cross section with stepped widths of 30.5, 33.0, and 38.1 cm. An aluminum housing fitting snugly in this hole is lined with Boral or a gadolinium-bearing paint and is joined with a rubber gasket to the inner housing, so that the entire length can be purged with helium. This system provides an l/d ratio of 1/140 and a useful beam area at the exposure point of 38 cm x 38 cm. At 480 kW, the neutron flux there is 10 6 n/cm 2 sec and the gamma flux is 17 R/hr. Figure 2 is a reproduction of the first radiograph taken with the facility. (author)

  5. Exhaust properties of centre-column-limited plasmas on MAST

    International Nuclear Information System (INIS)

    Maddison, G.P.; Akers, R.J.; Brickley, C.; Gryaznevich, M.P.; Lott, F.C.; Patel, A.; Sykes, A.; Turner, A.; Valovic, M.

    2007-01-01

    The lowest aspect ratio possible in a spherical tokamak is defined by limiting the plasma on its centre column, which might therefore maximize many physics benefits of this fusion approach. A key issue for such discharges is whether loads exhausted onto the small surface area of the column remain acceptable. A first series of centre-column-limited pulses has been examined on MAST using fast infra-red thermography to infer incident power densities as neutral-beam heating was scanned from 0 to 2.5 MW. Simple mapping shows that efflux distributions on the column armour are governed mostly by magnetic geometry, which moreover spreads them advantageously over almost the whole vertical length. Hence steady peak power densities between sawteeth remained low, -2 , comparable with the target strike-point value in a reference diverted plasma at lower power. Plasma purity and normalized thermal energy confinement through the centre-column-limited (CCL) series were also similar to properties of MAST diverted cases. A major bonus of CCL geometry is a propensity for exhaust to penetrate through its inner scrape-off layer connecting to the column into an expanding outer plume, which forms a 'natural divertor'. Effectiveness of this process may even increase with plasma heating, owing to rising Shafranov shift and/or toroidal rotation. A larger CCL device could potentially offer a simpler, more economic next-step design

  6. Surface modification and column flotation of a massive ilmenite ore

    International Nuclear Information System (INIS)

    Fan, X.; Rowson, N.A.

    2002-01-01

    The main problems with ilmenite flotation in impeller-type flotation machines are the poor flotation behaviour of ilmenite and the negative effect of slimes. These cause high ilmenite losses in tailings even when a large dosage of fatty acid and fuel oil is consumed. In this study, microwave radiation pre-treatment and ilmenite surface activation were used to modify the surface properties of a massive ilmenite ore sample from Norway to improve ilmenite flotability. A column cell was used to minimize the negative effect of slimes on ilmenite separation efficiency. When ilmenite flotation was performed in a 1 litre Denver cell, the flotation recovery of titanium dioxide from the ilmenite ore sample was only 68.5% (31.1% TiO 2 ) under conventional flotation conditions. After microwave radiation pre-treatment for three minutes at 2600 W and 2.45 GHz, the ferrous ions on ilmenite particle surfaces were converted into ferric ions; hence, the recovery increased from 68.5% to 86.8%. The concentrate grade increased from 31.1% TiO 2 to 32.1% TiO 2 . In ilmenite activation flotation, Pb 2+ ions can be selectively adsorbed on to ilmenite particle surfaces as active sites and therefore enhance the adsorption of oleate ions on ilmenite surfaces. With the addition of 60 g/ton Pb(NO 3 ) 2 , ilmenite flotation recovery increased from 68.5% to 85.1%. However, the quality of ilmenite concentrates was not improved due to the negative effect of slimes. After a two stage cleaning, the grade of ilmenite concentrates was only about 31% TiO 2 . The combination of microwave radiation pre-treatment and the application of a column cell overcame both problems of poor flotability and the negative effect of slimes. When the Denver cell was replaced by a column cell and the massive ilmenite ore sample was pre-treated using microwave radiation for three minutes, the ilmenite concentrate grade increased from 31.1% TiO 2 to 42.9% TiO 2 and the titanium dioxide recovery increased from 68.5% to 90

  7. 2-Thiophenecarboxylic acid hydrazide Derivatives: Synthesis and Anti-Tuberculosis Studies

    Science.gov (United States)

    Fahmi, M. R. G.; Khumaidah, L.; Ilmiah, T. K.; Fadlan, A.; Santoso, M.

    2018-04-01

    One of the most frequent and widespread infectious diseases especially in developing countries is tuberculosis (TB). The number of TB drug resistant tend to increase, and there has been no new TB drug introduce since the 1960s. Six 2-Thiophenecarboxylic acid hydrazide derivatives were synthesized in 90-97% yields, and 2-thiophenecarbonylhydrazone-5, 7-dibromoisatin showed the highest activity in inhibiting M. tuberculosis H37Rv.

  8. Comparison of the release of constituents from granular materials under batch and column testing.

    Science.gov (United States)

    Lopez Meza, Sarynna; Garrabrants, Andrew C; van der Sloot, Hans; Kosson, David S

    2008-01-01

    Column leaching testing can be considered a better basis for assessing field impact data than any other available batch test method and thus provides a fundamental basis from which to estimate constituent release under a variety of field conditions. However, column testing is time-intensive compared to the more simplified batch testing, and may not always be a viable option when making decisions for material reuse. Batch tests are used most frequently as a simple tool for compliance or quality control reasons. Therefore, it is important to compare the release that occurs under batch and column testing, and establish conservative interpretation protocols for extrapolation from batch data when column data are not available. Five different materials (concrete, construction debris, aluminum recycling residue, coal fly ash and bottom ash) were evaluated via batch and column testing, including different column flow regimes (continuously saturated and intermittent unsaturated flow). Constituent release data from batch and column tests were compared. Results showed no significant difference between the column flow regimes when constituent release data from batch and column tests were compared. In most cases batch and column testing agreed when presented in the form of cumulative release. For arsenic in carbonated materials, however, batch testing underestimates the column constituent release for most LS ratios and also on a cumulative basis. For cases when As is a constituent of concern, column testing may be required.

  9. Rapid Determination of the Monosaccharide Composition and Contents in Tea Polysaccharides from Yingshuang Green Tea by Pre-Column Derivatization HPLC

    OpenAIRE

    Ai, Yujie; Yu, Zhi; Chen, Yuqiong; Zhu, Xiaojing; Ai, Zeyi; Liu, Shuyuan; Ni, Dejiang

    2016-01-01

    A pre-column derivatization high-performance liquid chromatography (HPLC) method was developed and optimized to characterize and quantify the monosaccharides present in tea polysaccharides (TPS) isolated from Yingshuang green tea. TPS sample was hydrolyzed with trifluoroacetic acid, subjected to pre-column derivatization using 1-phenyl-3-methyl-5-pyrazolone (PMP), and separated on an Agilent TC-C18 column (4.6 mm × 250 mm, 5 μm) with UV detection at 250 nm. A mixture of ten PMP derivatives of...

  10. Smooth H I Low Column Density Outskirts in Nearby Galaxies

    Science.gov (United States)

    Ianjamasimanana, R.; Walter, Fabian; de Blok, W. J. G.; Heald, George H.; Brinks, Elias

    2018-06-01

    The low column density gas at the outskirts of galaxies as traced by the 21 cm hydrogen line emission (H I) represents the interface between galaxies and the intergalactic medium, i.e., where galaxies are believed to get their supply of gas to fuel future episodes of star formation. Photoionization models predict a break in the radial profiles of H I at a column density of ∼5 × 1019 cm‑2 due to the lack of self-shielding against extragalactic ionizing photons. To investigate the prevalence of such breaks in galactic disks and to characterize what determines the potential edge of the H I disks, we study the azimuthally averaged H I column density profiles of 17 nearby galaxies from the H I Nearby Galaxy Survey and supplemented in two cases with published Hydrogen Accretion in LOcal GAlaxieS data. To detect potential faint H I emission that would otherwise be undetected using conventional moment map analysis, we line up individual profiles to the same reference velocity and average them azimuthally to derive stacked radial profiles. To do so, we use model velocity fields created from a simple extrapolation of the rotation curves to align the profiles in velocity at radii beyond the extent probed with the sensitivity of traditional integrated H I maps. With this method, we improve our sensitivity to outer-disk H I emission by up to an order of magnitude. Except for a few disturbed galaxies, none show evidence of a sudden change in the slope of the H I radial profiles: the alleged signature of ionization by the extragalactic background.

  11. Partial path column generation for the vehicle routing problem with time windows

    DEFF Research Database (Denmark)

    Petersen, Bjørn; Jepsen, Mads Kehlet

    2009-01-01

    This paper presents a column generation algorithm for the Vehicle Routing Problem with Time Windows (VRPTW). Traditionally, column generation models of the VRPTW have consisted of a Set Partitioning master problem with each column representing a route, i.e., a resource feasible path starting...... and ending at the depot. Elementary routes (no customer visited more than once) have shown superior results on difficult instances (less restrictive capacity and time windows). However, the pricing problems do not scale well when the number of feasible routes increases, i.e., when a route may contain a large...... number of customers. We suggest to relax that ‘each column is a route’ into ‘each column is a part of the giant tour’; a so-called partial path, i.e., not necessarily starting and ending in the depot. This way, the length of the partial path can be bounded and a better control of the size of the solution...

  12. Seismic Performance of High-Ductile Fiber-Reinforced Concrete Short Columns

    Directory of Open Access Journals (Sweden)

    Mingke Deng

    2018-01-01

    Full Text Available This study mainly aims to investigate the effectiveness of high-ductile fiber-reinforced concrete (HDC as a means to enhance the seismic performance of short columns. Six HDC short columns and one reinforced concrete (RC short column were designed and tested under lateral cyclic loading. The influence of the material type (concrete or HDC, axial load, stirrup ratio, and shear span ratio on crack patterns, hysteresis behavior, shear strength, deformation capacity, energy dissipation, and stiffness degradation was presented and discussed, respectively. The test results show that the RC short column failed in brittle shear with poor energy dissipation, while using HDC to replace concrete can effectively improve the seismic behavior of the short columns. Compared with the RC short column, the shear strength of HDC specimens was improved by 12.6–30.2%, and the drift ratio and the energy dissipation increases were 56.9–88.5% and 237.7–336.7%, respectively, at the ultimate displacement. Additionally, the prediction model of the shear strength for RC columns based on GB50010-2010 (Chinese code can be safely adopted to evaluate the shear strength of HDC short columns.

  13. Thermoelectric properties of Ba3Co2O6(CO3)0.7 containing one-dimensional CoO6 octahedral columns

    OpenAIRE

    Iwasaki, Kouta; Yamamoto, Teruhisa; Yamane, Hisanori; Takeda, Takashi; Arai, Shigeo; Miyazaki, Hidetoshi; Tatsumi, Kazuyoshi; Yoshino, Masahito; Ito, Tsuyoshi; Arita, Yuji; Muto, Shunsuke; Nagasaki, Takanori; Matsui, Tsuneo

    2009-01-01

    The thermoelectric properties of Ba3Co2O6(CO3)0.7 have been investigated using prismatic single crystals elongated along the c axis. Ba3Co2O6(CO3)0.7 has a pseudo-one-dimensional structure similar to that of 2H perovskite-type BaCoO3 and contains CoO6 octahedral columns running parallel to the c axis. The prismatic crystals are grown by a flux method using a K2CO3–BaCl2 flux. The electrical conductivity(σ) along the columns (c axis) exhibits a metallic behavior (670–320 S cm−1 in the temperat...

  14. Reference mean temperature for evaluation of performance of thermal diffusion column for isotope separation

    International Nuclear Information System (INIS)

    Yamamoto, Ichiro; Kanagawa, Akira

    1987-01-01

    In order to evaluate separative performance of a thermal diffusion column, a simplification is usually made in which the temperature dependence of the relevant properties such as thermal diffusion constant is ignored and some proper mean values evaluated at a specific ''mean'' temperature are used. Adoption of weighted average of temperature distribution is common for the ''mean'' temperature, but there exists no definite way of determining mean temperature. The present paper proposes a new reference mean temperature determined by the equation governing the free convection. It is based on the fact that the multiplication effect of free convection is essential to separation by thermal diffusion column. The reference mean temperature is related to pressure difference between top and bottom of column and is higher than a mass-averaged temperature (due to gravitational force) by a contribution of viscous force. The reference mean temperature was calculated, as a reference, for an Ar isotope separating column with an inner hot radius of 0.2 mm and an outer cold radius of 5 mm. The results confirmed the validity of an approximate formula expressing effects of temperature difference and ratio of inner and outer radii of column explicitly for the temperature. The reference mean temperature calculated from pressure difference given by axisymmetric solution of equations of change was in good agreement with the analytical solution. (author)

  15. Effects of a malfunctional column on conventional and FeedCol-simulated moving bed chromatography performance.

    Science.gov (United States)

    Song, Ji-Yeon; Oh, Donghoon; Lee, Chang-Ha

    2015-07-17

    The effects of a malfunctional column on the performance of a simulated moving bed (SMB) process were studied experimentally and theoretically. The experimental results of conventional four-zone SMB (2-2-2-2 configuration) and FeedCol operation (2-2-2-2 configuration with one feed column) with one malfunctional column were compared with simulation results of the corresponding SMB processes with a normal column configuration. The malfunctional column in SMB processes significantly deteriorated raffinate purity. However, the extract purity was equivalent or slightly improved compared with the corresponding normal SMB operation because the complete separation zone of the malfunctional column moved to a lower flow rate range in zones II and III. With the malfunctional column configuration, FeedCol operation gave better experimental performance (up to 7%) than conventional SMB operation because controlling product purity with FeedCol operation was more flexible through the use of two additional operating variables, injection time and injection length. Thus, compared with conventional SMB separation, extract with equivalent or slightly better purity could be produced from FeedCol operation even with a malfunctional column, while minimizing the decrease in raffinate purity (less than 2%). Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Preparation and evaluation of 400μm I.D. polymer-based hydrophilic interaction chromatography monolithic columns with high column efficiency.

    Science.gov (United States)

    Liu, Chusheng; Li, Haibin; Wang, Qiqin; Crommen, Jacques; Zhou, Haibo; Jiang, Zhengjin

    2017-08-04

    The quest for higher column efficiency is one of the major research areas in polymer-based monolithic column fabrication. In this research, two novel polymer-based HILIC monolithic columns with 400μm I.D.×800μm O.D. were prepared based on the thermally initiated co-polymerization of N,N-dimethyl-N-(3-methacrylamidopropyl)-N-(3-sulfopropyl) ammonium betaine (SPP) and ethylene glycol dimethacrylate (EDMA) or N,N'-methylenebisacrylamide (MBA). In order to obtain a satisfactory performance in terms of column permeability, mechanical stability, efficiency and selectivity, the polymerization parameters were systematically optimized. Column efficiencies as high as 142, 000 plates/m and 120, 000 plates/m were observed for the analysis of neutral compounds at 0.6mm/s on the poly(SPP-co-MBA) and poly(SPP-co-EDMA) monoliths, respectively. Furthermore, the Van Deemter plots for thiourea on the two monoliths were compared with that on a commercial silica based ZIC-HILIC column (3.5μm, 200Å, 150mm×300μm I.D.) using ACN/H 2 O (90/10, v/v) as the mobile phase at room temperature. It was noticeable that the Van Deemter curves for both monoliths, particularly the poly(SPP-co-MBA) monolith, are significantly flatter than that obtained for the ZIC-HILIC column, which indicates that in spite of their larger internal diameters, they yield better overall efficiency, with less peak dispersion, across a much wider range of usable linear velocities. A clearly better separation performance was also observed for nucleobases, nucleosides, nucleotides and small peptides on the poly(SPP-co-MBA) monolith compared to the ZIC-HILIC column. It is particularly worth mentioning that these 400μm I.D. polymer-based HILIC monolithic columns exhibit enhanced mechanical strength owing to the thicker capillary wall of the fused-silica capillaries. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Charge collection measurements in single-type column 3D sensors

    International Nuclear Information System (INIS)

    Scaringella, M.; Polyakov, A.; Sadrozinski, H.F.-W.; Bruzzi, M.; Tosi, C.; Boscardin, M.; Piemonte, C.; Pozza, A.; Ronchin, S.; Zorzi, N.; Dalla Betta, G.-F.

    2007-01-01

    We report on charge collection studies on 3D silicon detectors of single-type column n-diffusions in p-substrate, configured either as strip or as pad detectors. The charge is generated by penetrating beta particles from a 90 Sr source which, together with a scintillation counter, serves as an electron telescope. The charge collection as a function of bias voltage is compared with the depletion thickness derived from the measured C-V characteristics

  18. Development of fine-resolution analyses and expanded large-scale forcing properties: 2. Scale awareness and application to single-column model experiments

    Science.gov (United States)

    Feng, Sha; Li, Zhijin; Liu, Yangang; Lin, Wuyin; Zhang, Minghua; Toto, Tami; Vogelmann, Andrew M.; Endo, Satoshi

    2015-01-01

    three-dimensional fields have been produced using the Community Gridpoint Statistical Interpolation (GSI) data assimilation system for the U.S. Department of Energy's Atmospheric Radiation Measurement Program (ARM) Southern Great Plains region. The GSI system is implemented in a multiscale data assimilation framework using the Weather Research and Forecasting model at a cloud-resolving resolution of 2 km. From the fine-resolution three-dimensional fields, large-scale forcing is derived explicitly at grid-scale resolution; a subgrid-scale dynamic component is derived separately, representing subgrid-scale horizontal dynamic processes. Analyses show that the subgrid-scale dynamic component is often a major component over the large-scale forcing for grid scales larger than 200 km. The single-column model (SCM) of the Community Atmospheric Model version 5 is used to examine the impact of the grid-scale and subgrid-scale dynamic components on simulated precipitation and cloud fields associated with a mesoscale convective system. It is found that grid-scale size impacts simulated precipitation, resulting in an overestimation for grid scales of about 200 km but an underestimation for smaller grids. The subgrid-scale dynamic component has an appreciable impact on the simulations, suggesting that grid-scale and subgrid-scale dynamic components should be considered in the interpretation of SCM simulations.

  19. Investigation of Limit States Specified for Reinforced Concrete Column Members in TEC–2007

    Directory of Open Access Journals (Sweden)

    Umut HASGÜL

    2016-01-01

    Full Text Available In this study, the deformation based limit states stipulated for reinforced concrete members in the Turkish Earthquake Code (TEC were experimentally investigated. Thus four RC cantilever columns which have low concrete compressive strengths and have not adequate confinement, were subjected to constant axial load and cyclic lateral load history. In the study, firstly, the strain values representing the damage limits were converted to top of the column lateral displacements by using fundamentals of structural mechanics. Subsequently the column damages corresponding to the displacement demands were observed, hence limit states were evaluated. After conducting all column tests, it was noted that no column damage was observed for the immediate occupancy (IO performance level defined in the code. For the life safety (LS and collapse prevention (CP performance levels, though somewhat residual deformations occurred on the critical regions, the column members can pretty much sustain their lateral load capacities. It was also observed for all columns that significant damages and strength losses occurred beyond the collapse prevention level. The results of experimental study indicate that the evaluation procedure in the TEC is still in good relationship with the limit states even if the columns have not adequate compressive strength and confinement.

  20. Analysis of separation quality of scandium-46 and titanium using silica gel column

    International Nuclear Information System (INIS)

    Muhamad Basit Febrian; Yanuar Setiadi; Duyeh Setiawan; Titin Sri Mulyati; Nana Suherman

    2015-01-01

    In this study, quality test of scandium and titanium mixture separation system using a silica gel column has been conducted. This system will be used in the separation of medical radioisotopes of 47 Sc from TiO 2 enriched targets. 20 mg of TiO 2 and 5 mg of Sc 2 O 3 dissolved using 0.5 mL of 50% HF solvent with gentle heating at 60°C - 80°C for 1 hour then 4.5 mL H 2 O was added. Sc and Ti mixture is separated by passing it through a column of silica gel. In the determination of scandium released from silica gel, Sc-46 radiotracer was used. Only 51.60 ± 4.5% of 5 mg of scandium could be retained in the silica gel column. From 51.60% of absorbed scandium in the column, 98.29 ± 3.4% were eluted with 5 mL of H 2 O eluent. During elution of scandium from silica gel column, 2.81 grams of 20 mg of titanium came apart as breakthrough. In determination of recovery of titanium from silica gel, 51.76 ± 5.5% of the 20 mg Ti can be recovered from silica gel column using 5M HCl eluent, whereas remaining Ti were eluted using 40 ml of HCl 5M. Based on those result, it can be concluded that there are still titanium portion in scandium after the separation using a silica gel column. Further purification step using fresh silica gel column, can separate escaped titanium from scandium. (author)

  1. 3-D Imaging using Row--Column-Addressed 2-D Arrays with a Diverging Lens

    DEFF Research Database (Denmark)

    Bouzari, Hamed; Engholm, Mathias; Stuart, Matthias Bo

    2016-01-01

    It has been shown that row–column-addressed (RCA) 2-D arrays can be an inexpensive alternative to fully addressed 2-D arrays. Generally imaging with an RCA 2-D array is limited to its forward-looking volume region. Constructing a double-curved RCA 2-D array or applying a diverging lens over......, is designed for imaging down to 14 cm at a volume rate of 88 Hz. The curvilinear imaging performance of a λ/2-pitch 3 MHz 62+62 RCA 2-D array is investigated as a function of depth, using a diverging lens with f-number of -1. The results of this study demonstrate that the proposed beamforming approach...

  2. Evaluation of bioleaching column test of sulphide copper ore and copper concentrate using preconditioned surface

    Directory of Open Access Journals (Sweden)

    Videla Leiva Alvaro

    2016-01-01

    Full Text Available Bacterial activity can be related to the presence of Fe+3 in the solution, which drives copper oxidation during the secondary copper low grade sulfide ore leaching process. The present work evaluates improvements in kinetics of leaching when ferroxidans are preconditioned in an inert surface helping to build a biofilm which improves metabolism of the colony. The present work shows evaluation using laboratory columns to perform bioleaching during a 30 days period under three conditions: a base column with no inert surface, a column with loofa available for bacterial growth and conditioning, and finally a column with the loofa surface ground and distributed in the column among the particles.

  3. Characterization of Bubble Size Distributions within a Bubble Column

    OpenAIRE

    Shahrouz Mohagheghian; Brian R. Elbing

    2018-01-01

    The current study experimentally examines bubble size distribution (BSD) within a bubble column and the associated characteristic length scales. Air was injected into a column of water via a single injection tube. The column diameter (63–102 mm), injection tube diameter (0.8–1.6 mm) and superficial gas velocity (1.4–55 mm/s) were varied. Large samples (up to 54,000 bubbles) of bubble sizes measured via 2D imaging were used to produce probability density functions (PDFs). The PDFs were used to...

  4. GFRP seismic strengthening and structural heath monitoring of Portage Creek Bridge concrete columns

    International Nuclear Information System (INIS)

    Huffman, S.; Bagchi, A.; Mufti, A.; Neale, K.; Sargent, D.; Rivera, E.

    2006-01-01

    Located in Victoria British Columbia (BC), Canada, the Portage Creek Bridge is a 124m long, three-span structure with a reinforced concrete piers and abutments on H piles. The bridge was designed prior to the introduction of current bridge seismic design codes and construction practices. Therefore it was not designed to resist the earthquake forces as required by today's standards. The bridge is on a route classified as a Municipal Disaster Route scheduled to be retrofitted to prevent collapse during a design seismic event, with a return period of 475 years (i.e., an event with 105 probability of exceedance in 50 years). Conventional materials and methods were used to retrofit most of the bridge. The dynamic analysis of the bridge predicted the two tall columns of Pier No. 1 will form plastic hinges under an earthquake resulting an additional shear to the short columns of Pier No. 2. A non-liner static pushover analysis indicated the short columns will not be able to form plastic hinges prior to failure in shear. The innovative solution of Fiber Reinforced Polymer wraps (FRPs) was chosen to strengthen the short columns for shear without increasing the moment capacity. The FRP wraps and the bridge were instrumented as one of 36 demonstration projects across Canada sponsored by ISIS (Intelligent Sensing for Innovative Structure) Canada, federally funded Network of Centers of Excellence, to access the performance of FRP and the use of FOS (Fiber Optic Sensors) for Structural Health Monitoring (SHM). The two columns of the bridge pier were strengthened with GFRP (Glass Fiber Reinforced Polymer) wraps with eight bi-directional rosette type strain gauges and four long gauge fiber optic sensors attached to the outer layer of the wraps. In addition, two 3-D Crossbow accelerometers are installed on the pier cap above the columns and a traffic web-cam mounted above the deck at the pier location. The data is collected through high sped internet line to an interactive web page

  5. Tritium isotope separation by water distillation column packed with silica-gel beads

    International Nuclear Information System (INIS)

    Fukada, Satoshi

    2004-01-01

    Tritium enrichment or depletion by water distillation was investigated using a glass column of 32cm in height packed with silica-gel beads of 3.4mm in average diameter. The total separation factor of the silica-gel distillation column, α H-T , was compared with those of an open column distillation tower and of a column packed with stainless-steel Dixon rings. Depletion of the tritium activity in the distillate was enhanced by isotopic exchange with water absorbed on silica-gel beads that have a higher affinity for HTO than for H 2 O. The value of α H-T -1 of the silica-gel distillation column was about four times larger than that of a column without any packing and about two times larger than that of the Dixon-ring column. The improvement of α H-T by the silica-gel adsorbent indicated that the height of the distillation-adsorption column becomes shorter than that of the height of conventional distillation columns. (author)

  6. Studies on the wetting properties of plate surfaces used in pulsed extraction columns

    International Nuclear Information System (INIS)

    Tai Derong; Yang Xin; Wang Xinchang

    1991-01-01

    Many factors influence the hydrodynamic characteristics of pulsed column. Of all the factors the surface effect at liquid-liquid interfaces and liquid-solid boundaries may be the most influential factor to the state of droplets. In order to get some understanding of the behaviour of droplets in a pulsed column, the time history of wetting properties of plates under different conditions in 30% TBP (Kerosene) -HNO 3 -UO 2 (NO 3 ) 2 -H 2 O systems was studied. The results show that the hydrophilic wetting behaviour of the plates changes into the hydrophobic and neutral conditions, respectively after they have been exposed to air and put in the 'open system' within about 50 days after contacting with process solutions. For the case where the access of air is prohibited at the upper organic phase boundary by a well fitting cover, or supersonic pulse cleaning is used to the cartridge, the behaviour of the metal surface stays in the original good hydrophilic wetting condition constant with time. The uranium charged liquid systems can conserve hydrophilic behaviour better than the non-charged systems under identical conditions. It is also found that the interfacial tension is unvaried with time for saturated process systems, hence it has no effects on the variation of wettability

  7. Novel design for centrifugal counter-current chromatography: VI. Ellipsoid column.

    Science.gov (United States)

    Gu, Dongyu; Yang, Yi; Xin, Xuelei; Aisa, Haji Akber; Ito, Yoichiro

    2015-01-01

    A novel ellipsoid column was designed for centrifugal counter-current chromatography. Performance of the ellipsoid column with a capacity of 3.4 mL was examined with three different solvent systems composed of 1-butanol-acetic acid-water (4:1:5, v/v) (BAW), hexane-ethyl acetate-methanol-0.1 M HCl (1:1:1:1, v/v) (HEMH), and 12.5% (w/w) PEG1000 and 12.5% (w/w) dibasic potassium phosphate in water (PEG-DPP) each with suitable test samples. In dipeptide separation with BAW system, both stationary phase retention (Sf) and peak resolution (Rs) of the ellipsoid column were much higher at 0° column angle (column axis parallel to the centrifugal force) than at 90° column angle (column axis perpendicular to the centrifugal force), where elution with the lower phase at a low flow rate produced the best separation yielding Rs at 2.02 with 27.8% Sf at a flow rate of 0.07 ml/min. In the DNP-amino acid separation with HEMW system, the best results were obtained at a flow rate of 0.05 ml/min with 31.6% Sf yielding high Rs values at 2.16 between DNP-DL-glu and DNP-β-ala peaks and 1.81 between DNP-β-ala and DNP-L-ala peaks. In protein separation with PEG-DPP system, lysozyme and myolobin were resolved at Rs of 1.08 at a flow rate of 0.03 ml/min with 38.9% Sf. Most of those Rs values exceed those obtained from the figure-8 column under similar experimental conditions previously reported.

  8. Kinetics and Thermochemistry of the Br((sup 2)P3/2) + NO2 Association Reaction

    Science.gov (United States)

    Kreutter, K. D.; Nicovich, J. M.; Wine, P. H.

    1997-01-01

    A laser flash photolysis-resonance fluorescence technique has been employed to study the kinetics of the Br((sup 2)P3/2) + NO2 association reaction as a function of temperature (259-432 K) pressure (12.5 - 700 Torr), and buffer gas identity (He, Ar, H2, N2, CO2, CF4, SF6). The reaction is found to be in the falloff regime between third and second order over the entire range of conditions investigated. At temperatures below 350 K, the association reaction is found to be irreversible on the time scale of the experiment (approximately 30 ms). At higher temperatures reversible addition is observed, allowing equilibrium constants for BrNO2 formation and dissociation to be determined. Second- and third-law analyses of the equilibrium data are in only fair agreement and lead to the following thermochemical parameters for the association reaction: Delta-H(298) = 19.6 +/- 1.7 kcal/mol, Delta-H(0) = -18.6 +/- 2.0 kcal/mol, Delta-S(298) = 29.3 +/- 4.2 cal/mol/K, Delta-H(sub f)(sub 298)(BrNO2) = 17.0 +/-1.8 kcal/mol(uncertainties are 2 sigma estimates of absolute accuracy). The value for Delta-H(0) determined in this study has been employed to calculate k(sub 0)(sup SC), the low-pressure third-order rate coefficient in the strong collision limit, by using the method of Troe; calculated values of k(sub 0)(sup SC) are inconsistent with experimental results unless Delta-H(0) is assigned a value near the lower limit derived from analysis of the high-temperature approach to equilibrium data, i.e. delta-H(0) approximately equals -16.6 kcal/mol. A potential source of systematic error in the calculation of both k(sub 0)(sup SC) and the absolute entropy of BrNO2 results from the complete lack of knowledge of the energies and degeneracies of the electronic states of BrNO3. The procedure developed by Troe and co-workers has been employed to extrapolate experimental falloff curves to the low- and high-pressure limits. Derived values for k(sub 0)(M,298K) in units of 10(exp -31) cm(exp 6

  9. Synthesis of 2-phosphaadamantane derivatives

    International Nuclear Information System (INIS)

    Zemlyanoi, V.N.; Aleksandrov, A.M.; Kukhar', V.P.

    1986-01-01

    The authors describe the synthesis and properties of 2-phosphadamantane derivatives. For the synthesis of 2-phosphaadamantane derivatives they decided to use the methodology of the synthesis of 2-thiaadamantane. The IR spectra were determined on CHCl 3 solutions with a Specord 711R spectrometer, the PMR spectra were determined on Tesla BS-467 (60 MHz) and Bruker WP-200 (200 MHz) spectrometers, external standard hexamethyldisiloxane, the 31 P NMR spectra were determined on Tesla BS-487 C (30 MHz) and Bruker WP-200 (81 MHz) spectrometers, external standard 85% phosphoric acid, and the mass spectra were determined on an MS-1302 spectrometer

  10. Formation of electrostatic double-layers and electron-holes in a low pressure mercury plasma column

    International Nuclear Information System (INIS)

    Petraconi, G; Maciel, Homero S

    2003-01-01

    Experimental studies of the formation of electrostatic double layers (DLs) and electron-holes (e-holes) are reported. The measurements were performed in the positive column of a mercury arc discharge operating in the low-pressure range of (2.0-14.0) x 10 -2 Pa with current density in the range of (3.0-8.0) x 10 3 A m -2 . Stable and unstable modes of the discharge were identified as the current was gradually increased, keeping constant the vapour pressure. The discharge remains stable until a critical current from which a slight increase of the current leads to an unstable regime characterized by high discharge impedance and strong oscillations. This mode ceased after a DL was formed in the plasma column. To induce the DL formation and to transport it smoothly along the discharge column, a low intensity B-field (7-10) x 10 -3 T produced by a movable single coil was used. The B-field locally increases the electron current density and makes the DL form at the centre of the magnetic constriction where it remained at rest. Electrostatic potential structures compatible with ordinary DLs and multiple-layers could be formed in the plasma column by dealing with the combined effects of the operational parameters of the discharge. It is noticeable that a pure e-hole, which is a symmetric triple-layer having a bell shape potential profile, could easily be formed by means of this experimental technique. A partial kinetic description, based on the space charge structure derived from an experimental e-hole, is presented in order to infer the charged particle populations that could contribute to the space charge of the e-hole. Evidence is shown that strong e-hole formation might be driven by an ion beam, therefore it could not be formed in isolation since its formation requires a nearby ion accelerating potential structure. Probe measurements of the plasma properties, at various radial positions of the stable positive column, are also presented. In the stable mode, prior to

  11. The Application of TD/GC/NICI-MS with an Al2O3-PLOT-S Column for the Determination of Perfluoroalkylcycloalkanes in the Atmosphere.

    Science.gov (United States)

    Ren, Yu; Schlager, Hans; Martin, Damien

    2014-01-01

    A modified method for the quantitative determination of atmospheric perfluoroalkylcycloalkanes (PFCs) using thermal desorption coupled with gas chromatography and detection by negative ion chemical ionization-mass spectrometry was developed. Using an optimized analytical system, a commercially available Al 2 O 3 porous layer open tubular (PLOT) capillary column (30 m × 0.25 mm) deactivated with Na 2 SO 4 was used for separation of PFCs. Improvements in the separation of PFCs, the corresponding identification and the limit of detection of PFCs using this method and column are presented. The method was successfully applied to determine the atmospheric background concentrations of a range of PFCs from a number of samples collected at a rural site in Germany. The results of this study suggest that the method outlined using the Al 2 O 3 -PLOT-S capillary column has good sensitivity and selectivity, and that it can be deployed in a routine laboratory process for the analysis of PFCs in the future research work. In addition, the ability of this column to separate the isomers of one of the lower boiling PFCs (perfluorodimethylcyclobutane) and its ability to resolve perfluoroethylcyclohexane offer the opportunity for single-column analysis for multiple PFCs.

  12. In situ Dynamics of O2, pH, Light, and Photosynthesis in Ikaite Tufa Columns (Ikka Fjord, Greenland)-A Unique Microbial Habitat.

    Science.gov (United States)

    Trampe, Erik C L; Larsen, Jens E N; Glaring, Mikkel A; Stougaard, Peter; Kühl, Michael

    2016-01-01

    The Ikka Fjord (SW Greenland) harbors a unique microbial habitat in the form of several hundred submarine tufa columns composed of ikaite, a special hexahydrate form of calcium carbonate that precipitates when alkaline phosphate- and carbonate-enriched spring water seeping out of the sea floor meets cold seawater. While several unique heterotrophic microbes have been isolated from the tufa columns, the microbial activity, and the boundary conditions for microbial growth in ikaite have remained unexplored. We present the first detailed in situ characterization of the physico-chemical microenvironment and activity of oxygenic phototrophs thriving within the ikaite columns. In situ underwater microsensor measurements of pH, temperature, and irradiance in the porous ikaite crystal matrix, revealed an extreme microenvironment characterized by low temperatures, strong light attenuation, and gradients of pH changing from pH 9 at the outer column surface to above pH 10 over the first 1-2 cm of the ikaite. This outer layer of the freshly deposited ikaite matrix contained densely pigmented yellow and green zones harboring a diverse phototrophic community dominated by diatoms and cyanobacteria, respectively, as shown by amplicon sequencing. In situ O2 measurements, as well as underwater variable chlorophyll fluorescence measurements of photosynthetic activity, demonstrated high levels of oxygenic photosynthesis in this extreme gradient environment with strong irradiance-driven O2 dynamics ranging from anoxia to hyperoxic conditions in the ikaite matrix, albeit the local formation of gas bubbles buffered the day-night dynamics of O2 in the tufa columns. The microbial phototrophs in the ikaite matrix are embedded in exopolymers forming endolithic biofilms that may interact with mineral formation and cementing of ikaite crystals.

  13. Ontogeny of the vertebral column of Eleutherodactylus johnstonei (Anura: Eleutherodactylidae) reveals heterochronies relative to metamorphic frogs.

    Science.gov (United States)

    Meza-Joya, Fabio Leonardo; Ramos-Pallares, Eliana Patricia; Ramírez-Pinilla, Martha Patricia

    2013-07-01

    Over the last century, the morphogenesis of the vertebral column has been considered as a highly conserved process among anurans. This statement is based on the study of few metamorphic taxa, ignoring the role of developmental mechanisms underlying the evolution of specialized life-histories. Direct development in anurans has been regarded as evolutionarily derived and involves developmental recapitulation and repatterning at different levels in all amphibian taxa studied so far. Herein, we analyze the vertebral column morphogenesis of the direct-developing frog Eleutherodactylus johnstonei, describing the sequence of chondrification and ossification, based on cleared and double-stained specimens from early stage embryos to adults. In general, our results show that the morphogenesis of the vertebral column in E. johnstonei recapitulates the ancestral tadpole-like pattern of development. However, the analysis of the sequence of events using heterochrony plots shows important heterocronies relative to metamorphic species, such as a delay in the chondrification of the vertebral centra and in osteogenesis. These ontogenetic peculiarities may represent derived traits in direct-developing frogs and are possibly correlated with its unusual life history. In addition, several features of the vertebral column of E. johnstonei are highly variable from its typical morphology. We report some malformations and small deviations, which do not seem to affect the survival of individuals. These anomalies have also been found in other frogs, and include many vertebral defects, such as vertebral fusion, and vertebral preclusion and/or induction. Copyright © 2013 Wiley Periodicals, Inc.

  14. Simulation of startup period of hydrogen isotope separation distillation column

    International Nuclear Information System (INIS)

    Sazonov, A.B.; Kagramanov, Z.G.; Magomedbekov, Eh.P.

    2003-01-01

    Kinetic procedure for the mathematical simulation of start-up regime of rectification columns for molecular hydrogen isotope separation was developed. Nonstationary state (start-up period) of separating column for rectification of multi-component mixture was calculated. Full information on equilibrium and kinetic physicochemical properties of components in separating mixtures was used for the calculations. Profile of concentration of components by height of column in task moment of time was calculated by means of differential equilibriums of nonstationary mass transfer. Calculated results of nonstationary state of column by the 2 m height, 30 mm diameter during separation of the mixture: 5 % protium, 70 % deuterium, 25 % tritium were illustrated [ru

  15. Determination of imidazole derivatives by micellar electrokinetic chromatography combined with solid-phase microextraction using activated carbon-polymer monolith as adsorbent.

    Science.gov (United States)

    Shih, Yung-Han; Lirio, Stephen; Li, Chih-Keng; Liu, Wan-Ling; Huang, Hsi-Ya

    2016-01-08

    In this study, an effective method for the separation of imidazole derivatives 2-methylimidazole (2-MEI), 4- methylimidazole (4-MEI) and 2-acetyl-4-tetrahydroxybutylimidazole (THI) in caramel colors using cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography (CSEI-sweeping-MEKC) was developed. The limits of detection (LOD) and quantitation (LOQ) for the CSEI-sweeping-MEKC method were in the range of 4.3-80μgL(-1) and 14-270μgL(-1), respectively. Meanwhile, a rapid fabrication activated carbon-polymer (AC-polymer) monolithic column as adsorbent for solid-phase microextraction (SPME) of imidazole colors was developed. Under the optimized SPME condition, the extraction recoveries for intra-day, inter-day and column-to-column were in the range of 84.5-95.1% (<6.3% RSDs), 85.6-96.1% (<4.9% RSDs), and 81.3-96.1% (<7.1% RSDs), respectively. The LODs and LOQs of AC-polymer monolithic column combined with CSEI-sweeping-MEKC method were in the range of 33.4-60.4μgL(-1) and 111.7-201.2μgL(-1), respectively. The use of AC-polymer as SPME adsorbent demonstrated the reduction of matrix effect in food samples such as soft drink and alcoholic beverage thereby benefiting successful determination of trace-level caramel colors residues using CSEI-sweeping-MEKC method. The developed AC-polymer monolithic column can be reused for more than 30 times without any significant loss in the extraction recovery for imidazole derivatives. Copyright © 2015 Elsevier B.V. All rights reserved.

  16. Constraints on Eurasian ship NOx emissions using OMI NO2 observations and GEOS-Chem

    Science.gov (United States)

    Vinken, Geert C. M.; Boersma, Folkert; van Donkelaar, Aaron; Zhang, Lin

    2013-04-01

    Ships emit large quantities of nitrogen oxides (NOx = NO + NO2), important precursors for ozone (O3) and particulate matter formation. Ships burn low-grade marine heavy fuel due to the limited regulations that exist for the maritime sector in international waters. Previous studies showed that global ship NOx emission inventories amount to 3.0-10.4 Tg N per year (15-30% of total NOx emissions), with most emissions close to land and affecting air quality in densely populated coastal regions. Bottom-up inventories depend on the extrapolation of a relatively small number of measurements that are often unable to capture annual emission changes and can suffer from large uncertainties. Satellites provide long-term, high-resolution retrievals that can be used to improve emission estimates. In this study we provide top-down constraints on ship NOx emissions in major European ship routes, using observed NO2 columns from the Ozone Monitoring Instrument (OMI) and NO2 columns simulated with the nested (0.5°×0.67°) version of the GEOS-Chem chemistry transport model. We use a plume-in-grid treatment of ship NOx emissions to account for in-plume chemistry in our model. We ensure consistency between the retrievals and model simulations by using the high-resolution GEOS-Chem NO2 profiles as a priori. We find evidence that ship emissions in the Mediterranean Sea are geographically misplaced by up to 150 km and biased high by a factor of 4 as compared to the most recent (EMEP) ship emission inventory. Better agreement is found over the shipping lane between Spain and the English Channel. We extend our approach and also provide constraints for major ship routes in the Red Sea and Indian Ocean. Using the full benefit of the long-term retrieval record of OMI, we present a new Eurasian ship emission inventory for the years 2005 to 2010, based on the EMEP and AMVER-ICOADS inventories, and top-down constraints from the satellite retrievals. Our work shows that satellite retrievals can

  17. Nitrogen transformations and greenhouse gas emissions from a riparian wetland soil: An undisturbed soil column study

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Leoz, Borja [Department of Chemical and Environmental Engineering, University of the Basque Country, UPV/EHU, E-48013 Bilbao (Spain); Antigueedad, Inaki [Department of Geodynamic, University of the Basque Country, UPV/EHU, E-48940 Leioa (Spain); Garbisu, Carlos [Department of Ecosystems, NEIKER-Tecnalia, E-48160 Derio (Spain); Ruiz-Romera, Estilita, E-mail: estilita.ruiz@ehu.es [Department of Chemical and Environmental Engineering, University of the Basque Country, UPV/EHU, E-48013 Bilbao (Spain)

    2011-01-15

    Riparian wetlands bordering intensively managed agricultural fields can act as biological filters that retain and transform agrochemicals such as nitrate and pesticides. Nitrate removal in wetlands has usually been attributed to denitrification processes which in turn imply the production of greenhouse gases (CO{sub 2} and N{sub 2}O). Denitrification processes were studied in the Salburua wetland (northern Spain) by using undisturbed soil columns which were subsequently divided into three sections corresponding to A-, Bg- and B2g-soil horizons. Soil horizons were subjected to leaching with a 200 mg NO{sub 3}{sup -} L{sup -1} solution (rate: 90 mL day{sup -1}) for 125 days at two different temperatures (10 and 20 {sup o}C), using a new experimental design for leaching assays which enabled not only to evaluate leachate composition but also to measure gas emissions during the leaching process. Column leachate samples were analyzed for NO{sub 3}{sup -} concentration, NH{sub 4}{sup +} concentration, and dissolved organic carbon. Emissions of greenhouse gases (CO{sub 2} and N{sub 2}O) were determined in the undisturbed soil columns. The A horizon at 20 {sup o}C showed the highest rates of NO{sub 3}{sup -} removal (1.56 mg N-NO{sub 3}{sup -} kg{sup -1} DW soil day{sup -1}) and CO{sub 2} and N{sub 2}O production (5.89 mg CO{sub 2} kg{sup -1} DW soil day{sup -1} and 55.71 {mu}g N-N{sub 2}O kg{sup -1} DW soil day{sup -1}). For the Salburua wetland riparian soil, we estimated a potential nitrate removal capacity of 1012 kg N-NO{sub 3}{sup -} ha{sup -1} year{sup -1}, and potential greenhouse gas emissions of 5620 kg CO{sub 2} ha{sup -1} year{sup -1} and 240 kg N-N{sub 2}O ha{sup -1} year{sup -1}. - Research Highlights: {yields}A new experimental design is proposed for leaching assays to simulate nitrogen transformations in riparian wetland soil. {yields}Denitrification is the main process responsible for nitrate removal in the riparian zone of Salburua wetland. {yields

  18. The breeding of a wheat mutant pollen-derived variety Chuanfu No.5 and the related techniques

    International Nuclear Information System (INIS)

    Xuan Pu; Yin Chunrong; Yue Chunfang; Qu Shihong

    2002-01-01

    With the treatment of 150 Gy 60 Co-γ irradiation to the dry F 1 (Mianyang 88-334 x 8811525) hybrid seeds and the donor plants chosen from MF 2 , wheat anther culture was made based on MW 14 and modified MS media and the pure diploid lines of MH 1 derived from anther pollen were obtained. In 1996, the new mutant line 6086 and its sibling lines, 6086 and 6087, were selected and bred successfully. In 2002, the mutant pollen-derived line 6086 was denominated as Chuanfu No.5 by Sichuan Crop Variety Identification Committee and became the first mutant variety via anther culture of wheat in Sichuan. The success of Chuanfu No.5 shown that combining radiation induction and anther technique could shorten the breeding period and increase the efficiency of breeding of wheat

  19. Prediction of ion-exchange column breakthrough curves by constant-pattern wave approach.

    Science.gov (United States)

    Lee, I-Hsien; Kuan, Yu-Chung; Chern, Jia-Ming

    2008-03-21

    The release of heavy metals from industrial wastewaters represents one of major threats to environment. Compared with chemical precipitation method, fixed-bed ion-exchange process can effectively remove heavy metals from wastewaters and generate no hazardous sludge. In order to design and operate fixed-bed ion-exchange processes successfully, it is very important to understand the column dynamics. In this study, the column experiments for Cu2+/H+, Zn2+/H+, and Cd2+/H+ systems using Amberlite IR-120 were performed to measure the breakthrough curves under varying operating conditions. The experimental results showed that total cation concentration in the mobile-phase played a key role on the breakthrough curves; a higher feed concentration resulted in an earlier breakthrough. Furthermore, the column dynamics was also predicted by self-sharpening and constant-pattern wave models. The self-sharpening wave model assuming local ion-exchange equilibrium could provide a simple and quick estimation for the breakthrough volume, but the predicted breakthrough curves did not match the experimental data very well. On the contrary, the constant-pattern wave model using a constant driving force model for finite ion-exchange rate provided a better fit to the experimental data. The obtained liquid-phase mass transfer coefficient was correlated to the flow velocity and other operating parameters; the breakthrough curves under varying operating conditions could thus be predicted by the constant-pattern wave model using the correlation.

  20. Measurements of CO2 Column Abundance in the Low Atmosphere Using Ground Based 1.6 μm CO2 DIAL

    Science.gov (United States)

    Abo, M.; Shibata, Y.; Nagasawa, C.

    2017-12-01

    Changes in atmospheric carbon dioxide (CO2) concentration are believed to produce the largest radiative forcing for the current climate system. Accurate predictions of atmospheric CO2 concentration rely on the knowledge of its sinks and sources, transports, and its variability with time. Although this knowledge is currently unsatisfactory, numerical models use it as a way in simulating CO2 fluxes. Validating and improving the global atmospheric transport model, therefore, requires precise measurement of the CO2 concentration profile. There are two further variations on Lidar: the differential absorption Lidar (DIAL) and the integrated path differential absorption (IPDA) Lidar. DIAL/IPDA are basically for profile/total column measurement, respectively. IPDA is a special case of DIAL and can measure the total column-averaged mixing ratio of trace gases using return signals from the Earth's surface or from thick clouds based on an airborne or a satellite. We have developed a ground based 1.6 μm DIAL to measure vertical CO2 mixing ratio profiles from 0.4 to 2.5 km altitude. The goals of the CO2 DIAL are to produce atmospheric CO2 mixing ratio measurements with much smaller seasonal and diurnal biases from the ground surface. But, in the ground based lidar, return signals from around ground surface are usually suppressed in order to handle the large dynamic range. To receive the return signals as near as possible from ground surface, namely, the field of view (FOV) of the telescope must be wide enough to reduce the blind range of the lidar. While the return signals from the far distance are very weak, to enhance the sensitivity and heighten the detecting distance, the FOV must be narrow enough to suppress the sky background light, especially during the daytime measurements. To solve this problem, we propose a total column measurement method from the ground surface to 0.4 km altitude. Instead of strong signals from thick clouds such as the IPDA, the proposed method uses

  1. Thermal process of an air column

    International Nuclear Information System (INIS)

    Lee, F.T.

    1994-01-01

    Thermal process of a hot air column is discussed based on laws of thermodynamics. The kinetic motion of the air mass in the column can be used as a power generator. Alternatively, the column can also function as a exhaust/cooler

  2. On Stability of a Bubble Column

    Czech Academy of Sciences Publication Activity Database

    Růžička, Marek

    2013-01-01

    Roč. 91, č. 2 (2013), s. 191-203 ISSN 0263-8762 R&D Projects: GA ČR GA104/07/1110 Institutional support: RVO:67985858 Keywords : bubble column * flow regimes * steady solution Subject RIV: CI - Industrial Chemistry, Chemical Engineering Impact factor: 2.281, year: 2013

  3. Retrieval of water vapor column abundance and aerosol properties from ChemCam passive sky spectroscopy

    Science.gov (United States)

    McConnochie, Timothy H.; Smith, Michael D.; Wolff, Michael J.; Bender, Steve; Lemmon, Mark; Wiens, Roger C.; Maurice, Sylvestre; Gasnault, Olivier; Lasue, Jeremie; Meslin, Pierre-Yves; Harri, Ari-Matti; Genzer, Maria; Kemppinen, Osku; Martínez, Germán M.; DeFlores, Lauren; Blaney, Diana; Johnson, Jeffrey R.; Bell, James F.

    2018-06-01

    We derive water vapor