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Sample records for aerosol ot aot

  1. Coexisting aggregates in mixed aerosol OT and cholesterol microemulsions.

    PubMed

    Sedgwick, Myles A; Trujillo, Alejandro M; Hendricks, Noah; Levinger, Nancy E; Crans, Debbie C

    2011-02-01

    Dynamic light scattering and NMR spectroscopic experimental evidence suggest the coexistence of two compositionally different self-assembled particles in solution. The self-assembled particles form in solutions containing water, Aerosol OT (AOT, sodium bis(2-ethylhexyl) sulfosuccinate) surfactant, and cholesterol in cyclohexane. In a similar series of studies carried out in 1-octanol only one aggregate type, that is, reverse micelles, is observed. Dynamic light scattering measurements reveal the presence of two different types of aggregates in the microemulsions formed in cyclohexane, demonstrating the coexistence of two compositionally distinct structures with very similar Gibbs energies. One particle type consists of standard AOT reverse micelles while the second type of particle consists of submicellar aggregates including cholesterol as well as small amounts of AOT and water. In microemulsions employing 1-octanol as the continuous medium, AOT reverse micelles form in a dispersed solution of cholesterol in 1-octanol. Although the size distribution of self-assembled particles is well-known for many different systems, evidence for simultaneous formation of two distinctly sized particles in solution that are chemically different is unprecedented. The ability to form microemulsion solutions that contain coexisting particles may have important applications in drug formulation and administration, particularly as applied to drug delivery using cholesterol as a targeting agent. PMID:21188993

  2. Aerosol-OT-gamma-alumina admicelles for the concentration of hydrophobic organic compounds in water.

    PubMed

    Saitoh, Tohru; Matsushima, Seiichi; Hiraide, Masataka

    2004-06-25

    A novel admicelle composing of a dialkylated anionic surfactant, di-2-ethylhexyl sodium sulfosuccinate (Aerosol-OT, AOT) and gamma-alumina was prepared by mixing them in acidic aqueous solution. The amount of the maximum sorption of AOT on 1 g of alumina at pH 2 was ca. 130 mg. By comparing the fluorescence spectra of N-phenyl-1-naphthylamine in different solvents, the solvent property of AOT-gamma-alumina admicelles was corresponding to that of toluene or diethyl ether. Thus, the AOT-gamma-alumina admicelles had greater hydrophobicity than SDS-gamma-alumina admicelles having similar hydrophobicity to 1-octanol or ethyl acetate. Hydrophobic organic compounds, chlorophenols having more than three chloro substituents, octylphenol, nonylphenol, dibutyl phthalate was almost quantitatively (98% or more) collected onto AOT admicelles composing of 1.5 g gamma-alumina and 150 mg AOT. The greater collection yields rather than those in SDS-admicellar system were ascribable to greater hydrophobicity and stability of AOT admicelles. After the 500-fold concentration, traces (nM) of organic contaminants in water samples were successfully detected with an HPLC having a photometric detector. PMID:15230525

  3. Transport of charged Aerosol OT inverse micelles in nonpolar liquids.

    PubMed

    Karvar, Masoumeh; Strubbe, Filip; Beunis, Filip; Kemp, Roger; Smith, Ashley; Goulding, Mark; Neyts, Kristiaan

    2011-09-01

    Surfactants such as Aerosol OT (AOT) are commonly used to stabilize and electrically charge nonpolar colloids in devices such as electronic ink displays. The electrical behavior of such devices is strongly influenced by the presence of charged inverse micelles, formed by excess surfactant that does not cover the particles. The presence of charged inverse micelles results in increased conductivity of the solution, affecting both the energy consumption of the device and its switching characteristics. In this work, we use transient current measurements to investigate the electrical properties of suspensions of the surfactant Aerosol OT in dodecane. No particles are added, to isolate the effect of excess surfactant. The measured currents upon application of a voltage step are found to be exponentially decaying, and can be described by an analytical model based on an equivalent electric circuit. This behavior is physically interpreted, first by the high generation rate of charged inverse micelles giving the suspension resistor like properties, and second by the buildup of layers of charged inverse micelles at both electrodes, acting as capacitors. The model explains the measurements over a large range of surfactant concentrations, applied voltages, and device thicknesses. PMID:21728309

  4. Adsorption of Aerosol-OT at the calcite/water interface--comparison of the sodium and calcium salts.

    PubMed

    Stocker, Isabella N; Miller, Kathryn L; Welbourn, Rebecca J L; Clarke, Stuart M; Collins, Ian R; Kinane, Christian; Gutfreund, Philipp

    2014-03-15

    The adsorption of the surfactant Aerosol-OT (AOT) at the calcite-water interface has been investigated using batch adsorption isotherms and neutron reflection. The adsorption isotherms showed that NaAOT adsorption followed S-type adsorption behaviour with a maximum surface excess of 2.5 mg m(-2) but the method could not be used for the investigation of Ca(AOT)2 adsorption owing to the changes in the bulk phase behaviour of the solution. The surface excess, determined by neutron reflection at the critical micelle concentration (CMC), was 2.5 mg m(-2) for Ca(AOT)2 and 1.8 mg m(-2) for NaAOT. The time dependence of the NaAOT adsorption suggests a slow conversion from the sodium to the calcium salt of AOT at the calcite-water interface by binding calcium ions released from the slightly soluble calcite. The layer thickness in both cases was 35 Å which indicates adsorption as bilayers or distorted micelles. At higher concentrations of NaAOT (~10× CMC) adsorption of an AOT lamellar phase was evident from Bragg peaks in the specular reflection. To our knowledge, this is the first time that adsorption of a surfactant at the calcite-water interface has been investigated by neutron reflection. The technique provided significant new insight into the adsorption behaviour of AOT which would not have been accessible using traditional techniques. PMID:24461829

  5. Effect of concentration and addition of ions on the adsorption of aerosol-OT to sapphire.

    PubMed

    Hellsing, Maja S; Rennie, Adrian R; Hughes, Arwel V

    2010-09-21

    Aerosol-OT (sodium bis 2-ethylhexyl sulfosuccinate or NaAOT) adsorbs to hydrophilic sapphire solid surfaces. The structure of the formed bilayer has been determined over the concentration range 0.2-7.4 mM NaAOT. It was found that the hydrocarbon tails pack at maximum packing limit at very low concentrations, and that the thickness of the bilayer was concentration-independent. The adsorption was found to increase with concentration, with the surfactant molecules packing closer laterally. The area per molecule was found to change from 138 ± 25 to 51 ± 4 A(2) over the concentration range studied, with the thickness of the layer being constant at 33 ± 2 A. Addition of small amounts of salt was found to increase the surface excess, with the bilayer being thinner with a slightly larger area per molecule. Addition of different salts of the same valency was found to have a very similar effect, as had the addition of NaOH and HCl. Hence, the effects of adding acid or base should be considered an effect of ionic strength rather than an effect of pH. Adsorption of NaAOT to the sapphire surface that carries an opposite charge to the anionic surfactant is similar in many respects to the adsorption reported previously for hydrophilic and hydrophobic silica surfaces. This suggests that the adsorption of NaAOT to a surface is driven primarily by NaAOT self-assembly rather than effects of electrostatic attraction to the interface. PMID:20735040

  6. Rotational reorientation dynamics of Aerosol-OT reverse micelles formed in near-critical propane

    SciTech Connect

    Heitz, M.P.; Bright, F.V.

    1996-06-01

    The rotational reorientation kinetics of two fluorescent solutes (rhodamine 6G, R6G, and rhodamine 101, R101) have been determined in sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol-OT, AOT) reverse micelles formed in liquid and near-critical propane. We show that the amount of water loading ([water]/[AOT], R), continuous phase density, and temperature all influence the solute rotational dynamics. In all cases, the decay of anisotropy data (i.e., frequency-dependent differential polarized phase angle and polarized modulation ratio) are well described by a bi-exponential decay law. We find that the faster rotational correlation times are similar to but slightly less than the values predicted for an individual AOT reverse micelle rotating in propane. The recovered rotational correlation times range from 200 to 500 ps depending on experimental conditions. This faster rotational process is explained in terms of lateral diffusion of the fluorophore along the water/headgroup interfacial region within the reverse micelle. The recovered values for the slower rotational correlation times range from 7 to 18 ns. These larger rotational reorientation times are assigned to varying micelle-micelle (i.e., tail-tail) interactions in the low-density, highly compressible fluid region. We also quantify the contribution of the reverse micellar {open_quotes}aggregate{close_quotes} to the total decay of anisotropy. {copyright} {ital 1996} {ital Society for Applied Spectroscopy}

  7. Unique effects of aerosol OT lamellar structures on the dynamics of guest molecules.

    PubMed

    De, Dipanwita; Datta, Anindya

    2013-06-25

    The behavior of lamellar structures of Aerosol OT (AOT) as hosts, vis-à-vis the flexible normal micelles and rigid nanochannels of Nafion membranes, has been investigated with two different fluorophores, [2,2'-bipyridyl]-3,3'-diol (BP(OH)2) and coumarin 102 (C102). Surprisingly, for BP(OH)2, a rise time is observed at intermediate emission wavelengths and not in the red edge of the fluorescence spectrum. A shoulder at 525 nm is observed in time resolved emission spectra (TRES) at initial times of BP(OH)2 in AOT lamellar structures. This feature is the signature of the monoketo (MK) tautomer, observed for the first time in a microheterogeneous medium. Also, the usually ultrafast single proton transfer in BP(OH)2 is retarded to an considerable extent in lamellar structures. The potential of this medium in promoting unusual intermediates is thus highlighted. This property may be ascribed to the rigidity of lamellar structures, compared to hosts such as regular micelles. However, studies using another fluorophore, coumarin 102 (C102), brings out the fact that these structures are significantly different from the rigid host, Nafion, as well. The absence of excited state proton transfer (ESPT) in this molecule in AOT lamellar structures indicates that it is not protonated, unlike in Nafion. Thus, the interfacial pH of lamellar structures is found to be significantly greater than that of Nafion nanochannels. From the time dependent Stokes shift (TDSS) of the emission spectra of C102, the relaxation time (0.85 ns) of interfacial water in lamellar structures is found to be an order of magnitude faster than that observed in Nafion nanochannels, in which H3O(+) ions have been substituted by different cations. Hence, this study demonstrates that AOT lamellar structures are rather unique hosts and that they behave very differently from conventional rigid and flexible hosts such as normal micelles and Nafion, respectively. PMID:23713719

  8. Probing the internal dynamics of reverse micelles formed in highly compressible solvents: Aerosol-OT in near-critical propane

    SciTech Connect

    Zhang, J.; Bright, F.V.

    1992-10-29

    In normal liquids, the rate of water reorganization within the interior of AOT (sodium bis(2-ethylhexyl) sulfosuccinate or Aerosol-OT) reverse micelles in a strong function of water loading and temperature. In this report, we discuss our most recent efforts to understand the internal dynamics of reverse micelles maintained in highly compressible solvents (near-critical propane). By using steady-state and time-resolved fluorescence spectroscopy, we report the first evidence for pressure-assisted control of the rate of solvent relaxation within the core region of a reverse micelle maintained in a highly compressible fluid. Three factors are taken into account in this study: amount of water loading, temperature, and bulk fluid density. The key conclusion is that the continuous phase density can influence the rate of solvent reorientation within the interior of AOT micelles formed in near-critical propane. 58 refs., 10 figs., 3 tabs.

  9. Synthesis and characterization of nanodispersed molecular aggregates of Prussian blue in aerosol OT reverse micelle.

    PubMed

    Pramanik, Smritimoy; Das, Debasmita; Das, Kaushik; Bhattacharya, Subhash Ch

    2007-02-01

    Prussian Blue (PB) nanomolecular aggregates were prepared in a well-characterized, monodispersed biomimicking nanocavities formed by Aerosol OT (AOT) reverse micelle in H2O/AOT/heptane at different omega ([H2O]/[Surfactant]) employing coprecipitation technique. The formed nanomolecular aggregates of PB have been characterized by the UV-visible, Fourier Transformed Infrared (FTIR) spectroscopy as well as by Transmission Electron Microscopy (TEM) and Cyclic Voltammetric methods. Visible and FTIR spectroscopic measurements confirm the formation of PB nano aggregates. Experimental results reveal that the molar extinction coefficient of PB nanomolecular aggregates is different for two different regimes of omega of reverse micelles. TEM measurements show that the size of these reverse micellar entrapped nano aggregrates varied with hydration (omega). Studies on these nano sized particles indicate that Fe is present in a single mixed valence state along the Fe-C-N-Fe skeleton in PB and the half wave potential (E1/2) becomes more positive with increase in the size of the nano aggregates. PMID:17450811

  10. Molecular simulation study of water mobility in aerosol-OT reverse micelles.

    PubMed

    Chowdhary, Janamejaya; Ladanyi, Branka M

    2011-06-16

    In this work, we present results from molecular dynamics simulations on the single-molecule relaxation of water within reverse micelles (RMs) of different sizes formed by the surfactant aerosol-OT (AOT, sodium bis(2-ethylhexyl)sulfosuccinate) in isooctane. Results are presented for RM water content w(0) = [H(2)O]/[AOT] in the range from 2.0 to 7.5. We show that translational diffusion of water within the RM can, to a good approximation, be decoupled from the translation of the RM through the isooctane solvent. Water translational mobility within the RM is restricted by the water pool dimensions, and thus, the water mean-squared displacements (MSDs) level off in time. Comparison with models of diffusion in confined geometries shows that a version of the Gaussian confinement model with a biexponential decay of correlations provides a good fit to the MSDs, while a model of free diffusion within a sphere agrees less well with simulation results. We find that the local diffusivity is considerably reduced in the interfacial region, especially as w(0) decreases. Molecular orientational relaxation is monitored by examining the behavior of OH and dipole vectors. For both vectors, orientational relaxation slows down close to the interface and as w(0) decreases. For the OH vector, reorientation is strongly affected by the presence of charged species at the RM interface and these effects are especially pronounced for water molecules hydrogen-bonded to surfactant sites that serve as hydrogen-bond acceptors. For the dipole vector, orientational relaxation near the interface slows down more than that for the OH vector due mainly to the influence of ion-dipole interactions with the sodium counterions. We investigate water OH and dipole reorientation mechanisms by studying the w(0) and interfacial shell dependence of orientational time correlations for different Legendre polynomial orders. PMID:21548627

  11. Seasonal differences in aerosol water may reconcile AOT and surface mass measurements in the Southeast U.S.

    NASA Astrophysics Data System (ADS)

    Nguyen, T. K. V.; Ghate, V. P.; Carlton, A. M. G.

    2015-12-01

    Summertime aerosol optical thickness (AOT) in the Southeast U.S. is high and sharply enhanced (2-3 times) compared to wintertime AOT. This seasonal pattern is unique to the Southeast U.S. and is of particular interest because temperatures there have not warmed over the past 100 years, contrasting with trends in other U.S. regions. Some investigators hypothesize the Southeast temperature trend is due to secondary organic aerosols (SOA) formed from interactions of biogenic volatile organic compounds (BVOCs) and anthropogenic emissions that create a cooling haze. However, aerosol measurements made at the surface do not exhibit strong seasonal differences in mass or organic fraction to support this hypothesis. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with surface mass measurements by examining trends in particle-phase liquid water, an aerosol constituent that effectively scatters radiation and is removed from aerosols in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIA (v2.1) to estimate surface and aloft aerosol water mass concentrations at locations of Interagency Monitoring of Protected Visual Environments (IMPROVE) sites using measured speciated ion mass concentrations and NCEP North American Regional Reanalysis (NARR) meteorological data. Results demonstrate strong seasonal differences in aerosol water in the eastern compared to the western part of the U.S., consistent with geographic patterns in AOT. The highest mean regional seasonal difference from 2000 to 2007 is 5.5 μg m-3 and occurs the Southeast, while the lowest is 0.44 μg m-3 and occurs in the dry Mountain West. Our findings suggest 1) similarity between spatial trends in aerosol water in the U.S. and previously published AOT data from the MODIS-TERRA instrument and 2) similar interannual trends in mean aerosol water and previously published interannual AOT trends from MISR, MODIS-TERRA, MODIS

  12. Vibrational energy relaxation of water in Aerosol OT reverse micelle

    NASA Astrophysics Data System (ADS)

    Pang, Yoonsoo; Deak, John; Dlott, Dana

    2005-03-01

    An IR-Raman technique with mid-IR pump and anti-Stokes Raman probe is used to investigate reverse micelle mixture of Aerosol OT, water, and carbon tetrachloride, where polar water phase and nonpolar oil phase is separated by a monolayer of surfactant molecules. Anti-Stokes Raman scattering is only dependent on the population of vibrationally excited states, thus time-dependent population changes of parent/daughter vibrations can be monitored with this technique. Vibrational energy from nanodroplet of water is transferred to the surfactant head group in 1.8 ps and then out to solvent in 10 ps. Vibrational energy directly pumped into the surfactant tail group results in a slower 20-40 ps energy transfer to solvent. This energy transfer cannot be explained by ordinary heat transfer, but the specific vibrational energy relaxation pathway such as sulfonate stretch of surfactant molecules should be used. We can change the water-to-solvent energy transfer rate by adopting different size of reverse micelles or changing pump frequency over the broad OH stretch mode of water due to hydrogen bond network. Water molecules confined in nanometer scale reverse micelles have very different properties from bulk water and we have found many differences between the vibrational dynamics of water in these reverse micelles and those of bulk water.

  13. Synthesis of nanosize silica in aerosol OT reverse microemulsions

    SciTech Connect

    Arriagada, F.J.; Osseo-Asare, K. . Dept. of Materials Science and Engineering)

    1995-03-01

    Silica nanoparticles were synthesized in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/decane/ammonium hydroxide reverse microemulsions via the base-catalyzed hydrolysis of tetraethoxysilane (TEOS). The fluorescence spectra of 1,3,6,8-pyrenetetrasulfonic acid (PTS) trapped in the water pools indicate that free water molecules do not become available until the water-to-surfactant molar ratio (R) exceeds about 10. At R values below about 4, no particles are produced. Under these conditions, the surfactant molecules are closely packed at the interface and the water molecules are strongly bound to the surfactant polar groups and the sodium counterions; the net result is to inhibit TEOS hydrolysis. As R increases from 5 to 9.5, the diameter of the resulting particles increases, and the size distribution decreases. These trends are rationalized in terms of changes in the local concentration of hydrolyzed TEOS species in the reversed micellar pseudophase, coupled with the protective action of the surfactant film. The fact that the final particle sizes exceed the diameters of the corresponding water pools indicates a role for intermicellar matter exchange in the particle growth process. The dispersions are not stable, and gel-like precipitates eventually form. The low dispersion stability is attributed to the presence of sodium ions and to the possible decrease in pH caused by the hydrolysis of the AOT surfactant molecules. This surfactant has been used in a number of applied investigations involving membrane chemistry, protein separations, metal separations, solar energy conversion, and nanoparticle synthesis.

  14. Distribution of polyphenols and a surfactant component in skin during Aerosol OT microemulsion-enhanced intradermal delivery.

    PubMed

    Yutani, Reiko; Morita, Shin-ya; Teraoka, Reiko; Kitagawa, Shuji

    2012-01-01

    As for most other polyphenols, intradermal delivery of curcumin and resveratrol is limited; however, it was significantly improved by a microemulsion using Aerosol OT (Aerosol OT microemulsion) and Tween 80 (Tween 80 microemulsion) as surfactants. Aerosol OT microemulsion was more effective and the incorporation ratio of these polyphenols into skin by Aerosol OT microemulsion was five-fold or ten-fold that by Tween 80 microemulsion. To clarify the mechanism of the enhancement we examined the distribution of these polyphenols and the surfactant component, Aerosol OT, using excised guinea pig skin and Yucatan micropig (YMP) skin. During permeation, polyphenols distributed deep in the skin. In particular, a small molecule, resveratrol, was mainly present in the dermis in YMP skin. Aerosol OT also distributed deep in the skin. These findings suggest the possible involvement of the interaction of surfactant molecules with skin components in the enhanced delivery process of polyphenols. The distribution ratio between the dermis and epidermis of the polyphenols, including quercetin, in the presence of Aerosol OT microemulsion decreased with the increase of molecular weight in YMP skin, suggesting the possibility that distribution to the dermis is regulated by the molecular size. PMID:22863702

  15. Estimation of AOT and SDS CMC in a methanol using conductometry, viscometry and pyrene fluorescence spectroscopy methods

    NASA Astrophysics Data System (ADS)

    Mitsionis, Anastasios I.; Vaimakis, Tiverios C.

    2012-09-01

    Critical micelle concentration (CMC) of two anionic surfactants in methanol was estimated using conductometry, viscometry and pyrene fluorescence spectroscopy methods. The surfactants used, were sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol-OT, AOT) and sodium dodecyl sulfate (SDS) dispersed in pure methanol. The CMC determination was evaluated in room temperature. The results have shown nearly similar concentrations.

  16. Retrieval of Maps of PM2.5 Aerosol in the Problematic California Valleys: Bright, Speckled Reflectances, Thin AOT, but High Pollution

    NASA Astrophysics Data System (ADS)

    Chatfield, R. B.

    2015-12-01

    The San Joaquin Valley suffers from severe episodes of respirable aerosol (PM2.5) in wintertime. We provide maps of aerosol episodes using daily snapshots of PM2.5 and its changing features despite numerous difficulties inherent to sampling the region, with special focus on the DISCOVER-AQ period, Jan-Feb 2013, which had many supporting measurements. Both high pollution and retrieval difficulties tend to occur in many Mediterranean agricultural regions. One difficulty is the relatively bright surfaces with considerable exposed soil. NASA's MAIAC and MODIS Deep Blue retrieval techniques are shown to have considerable skill even at low aerosol optical thickness (AOT) values, as evaluated by concurrent AERONET sunphotometer measurements. More significantly, these AOT values can correspond to high daytime PM2.5 since aerosol mixed layer depth is thin and variable, 200m - 600 m. The thin layers derive from typical subsidence of dry air between more stormy periods. This situation provides an advantage: water vapor column is also almost completely limited to a similar mixed layer depth, and can thus serve as a measure of aerosol dilution. The ratio of AOT to column-water-vapor from MODIS products provides two advantages: (1) it can provide a measure related to particle density, via a mixed-layer proxy, and (2) it can ratio out some errors that crop up in the retrieval of very low AOT, e.g. bidirectional reflectance and other angular dependences. These effects are combined, so we disentangle them using AERONET data. Data from the NASA Langley HSRL-2 lidar and in-situ measurements from DISCOVER-AQ are also helpful. At the time of abstract submission, sporadic errors in the column water estimates provide the greatest limitation. Looking to the near future, we suggest why the use of geostationary TEMPO data will allow multiple sampling opportunities per day, supplementary or alternative information for AOT, aerosol absorption, and even column water.

  17. Preparation and physicochemical characterization of dioctyl sodium sulfosuccinate (aerosol OT) microemulsion for oral drug delivery.

    PubMed

    El-Laithy, Hanan M

    2003-01-01

    The performance of dioctyl sodium sulfosuccinate (aerosol OT) in the development of a pharmaceutically acceptable, stable, self-emulsifying water continuous microemulsion with high dilution efficiency was assessed. A pseudoternary microemulsion system was constructed using aerosol OT/medium-chain triglycerides with oleic acid/glycerol monooleate and water. The model microemulsion was characterized with regard to its electroconductive behavior, eosin sodium absorption, interfacial tension, and droplet size measurements after dilution with water. The percolation transition law, which makes it possible to determine the percolation threshold and to identify bicontinuous structures, was applied to the system. The interfacial tension changes associated with the microemulsion formation revealed ultralow values up to 30% oil at a surfactant/cosurfactant ratio of 3:1. Moreover, the investigated particle size and polydispersity using photon correlation spectroscopy after dilution with excess of the continuous phase proved the efficiency of the microemulsion system as a drug carrier that ensures an infinitely dilutable, homogeneous, and thermodynamically stable system. PMID:12916920

  18. Phase behavior, transport properties, and thermodynamics of water/AOT/alkanol microemulsion systems

    SciTech Connect

    Ray, S.; Moulik, S.P.

    1995-07-01

    The phase diagrams of ternary systems of water/Aerosol-OT/alkanol (having carbon numbers 5, 6, 7, 8 and 10) are presented. Appreciable single-phase zones with viscous regions at higher proportions of Aerosol-OT (AOT) have been witnessed for all the alkanols. The ternary systems have also shown water-induced percolation of conductance with multistep phenomena in some cases. The viscous preparations have behaved like Bingham liquids (the viscosity has increased with the rate of shear). The enthalpy of the solubilization of water in alkanol/AOT medium has been calorimetrically determined to be positive; the free energy has been evaluated from the knowledge of maximum water intake until phase separation. The free energy and entropy of water solubilization (derived from Gibbs` equation) have been found to be positive and negative, respectively, and they follow a regular trend with the [alkanol]/[AOT] mole ratio (R) as well as with the alkanol carbon number. On the other hand, the enthalpy values, although they increased with R, increase with alkanol chainlength to a maximum for heptanol and then decrease for both octanol and decanol. It is considered that the heptanol acts as an efficient cosurfactant with AOT and helps to produce microdroplets with increased endothermicity.

  19. A Comparison of Seasonal and Interannual Variability of Soil Dust Aerosols Over the Atlantic Ocean as Inferred by the Toms AI and AVHRR AOT Retrievals

    NASA Technical Reports Server (NTRS)

    Cakmur, R. V.; Miller, R. L.; Tegen, Ina; Hansen, James E. (Technical Monitor)

    2001-01-01

    The seasonal cycle and interannual variability of two estimates of soil (or 'mineral') dust aerosols are compared: Advanced Very High Resolution Radiometer (AVHRR) aerosol optical thickness (AOT) and Total Ozone Mapping Spectrometer (TOMS) aerosol index (AI), Both data sets, comprising more than a decade of global, daily images, are commonly used to evaluate aerosol transport models. The present comparison is based upon monthly averages, constructed from daily images of each data set for the period between 1984 and 1990, a period that excludes contamination from volcanic eruptions. The comparison focuses upon the Northern Hemisphere subtropical Atlantic Ocean, where soil dust aerosols make the largest contribution to the aerosol load, and are assumed to dominate the variability of each data set. While each retrieval is sensitive to a different aerosol radiative property - absorption for the TOMS AI versus reflectance for the AVHRR AOT - the seasonal cycles of dust loading implied by each retrieval are consistent, if seasonal variations in the height of the aerosol layer are taken into account when interpreting the TOMS AI. On interannual time scales, the correlation is low at most locations. It is suggested that the poor interannual correlation is at least partly a consequence of data availability. When the monthly averages are constructed using only days common to both data sets, the correlation is substantially increased: this consistency suggests that both TOMS and AVHRR accurately measure the aerosol load in any given scene. However, the two retrievals have only a few days in common per month so that these restricted monthly averages have a large uncertainty. Calculations suggest that at least 7 to 10 daily images are needed to estimate reliably the average dust load during any particular month, a threshold that is rarely satisfied by the AVHRR AOT due to the presence of clouds in the domain. By rebinning each data set onto a coarser grid, the availability of

  20. Combining AOT, Angstrom Exponent and PM concentration data, with PSCF model, to distinguish fine and coarse aerosol intrusions in Southern France

    NASA Astrophysics Data System (ADS)

    Dimitriou, Konstantinos; Kassomenos, Pavlos

    2016-05-01

    In this paper, a cluster analysis of backward air mass trajectories, arriving in Avignon (Southern France), was combined with a Potential Source Contribution Function (PSCF) model on a 0.5° × 0.5° resolution grid, in order to indicate possible aerosol intrusions. A strict triple criterion was constructed from Aerosol Optical Thickness (AOT), Angstrom Exponent (AE), and PM (PM10 and PM2.5) concentration measurements, aiming to distinguish more effectively Episodes of Fine, Coarse and Overall Aerosols (FAE, CAE and OAE respectively). Large fractions of FAE (60.0%) and CAE (40.6%) were strongly attributed to the prevalence of Eastern and South-Southwest (S-SW) airflows respectively, whereas these distinct trajectory clusters also gathered large fractions of OAE (90.2% cumulatively). According to PSCF results, FAE events were strongly associated with the influence of air masses traveling over North Italy and Southern Germany, hence the impact of urban and industrial combustion was emerged. Main sources of coarse aerosols were principally isolated over the Mediterranean, thus the import of sea spray and dust from the Sahara desert is presumed. Satellite AOT observations were used for a more detailed identification of an intense 5-day intrusion of coarse aerosols. Short range slow moving air mass trajectories, were proven to be a clear marker of atmospheric stagnation, based on a wind speed analysis, triggering the accumulation of locally emitted anthropogenic aerosols (mainly PM2.5) and lack of city ventilation.

  1. Mesoscopic simulation study on phase diagram of the system oil/water/aerosol OT

    NASA Astrophysics Data System (ADS)

    Yuan, Shi-Ling; Cai, Zheng-Ting; Xu, Gui-Ying; Jiang, Yuan-Sheng

    2002-10-01

    A simple model, i.e., sodium bis(2-ethylhexyl) sulfosuccinate (AOT) represented by one-head and two-tail beads tied together by a harmonic spring and water or iso-octane by one bead, was put forward via dissipative particles dynamics (DPD) simulation method. Using the changes of interfacial tension between water and oil phase, a ternary phase diagram of AOT/water/iso-octane system was drawn.

  2. Interaction between morin and AOT reversed micelles--studies with UV-vis at 25 °C.

    PubMed

    Bhattarai, Ajaya; Wilczura-Wachnik, H

    2014-01-30

    The precise measurements of morin absorbance in presence of surfactant/solvent/water systems at 25 °C by UV-vis technique are reported. The surfactant used in presented study was sodium bis(2-ethylhexyl) sulfosuccinate called Aerosol-OT or AOT. The solvents selected were: ethanol, ethylene glycol, and n-decanol. The concentrations of AOT were varied between 0.001 and 0.4 mol/kg. Morin concentration in quvette during UV-vis registration was not equals in all solvent because of its different solubility and absorption intensity depending on the solvent. Water concentration in the studied systems was defined by R parameter according to relation: R=[H2O]/[AOT] and was equal 0, 30 and 40 in ethanol; 0, 10, 20 and 30 in ethylene glycol and 0, 10, 20, 30, and 40 in n-decanol. In presented work a Nernstian distribution of morin between the organic and micellar phases was assumed. The intensity of morin absorbance as a function of AOT concentration was analyzed. Using Non-linear Regression Procedure (NLREG) morin binding constant (K' [mol/kg]), and morin distribution constant (K) between organic phase and AOT micellar phase have been calculated. The experimental results have shown a significant influence of solvent, surfactant and water presence on morin UV-vis spectrum. Calculated data pointed out on different transfer of morin molecules from the organic to micellar phase depending on the solvent. Moreover, results of calculations indicate on competition between morin and water molecules interacting with AOT polar heads. Morin molecules privileged location in AOT reversed micelles strongly depends on the solvent. In case of systems with ethylene glycol as solvent is possible morin molecules location in polar cores of AOT reversed micelles as results of strong interaction between AOT polar heads and morin hydroxyl groups, whereas in case of ethanol and n-decanol morin molecules are located in palisade layer. PMID:24239834

  3. Adsorption of aerosol-OT to sapphire: lamellar structures studied with neutrons.

    PubMed

    Hellsing, Maja S; Rennie, Adrian R; Hughes, Arwel V

    2011-04-19

    The adsorption of sodium bis 2-ethylhexyl sulfosuccinate, NaAOT, to a sapphire surface from aqueous solution has been studied by neutron reflection at concentrations above the critical micelle concentration (cmc). Complementary measurements of the bulk structure were made with small-angle neutron scattering and grazing incidence small-angle neutron scattering. At a concentration of about 1% wt (10 × cmc), lamellar phase NaAOT was observed both at the surface and in the bulk. The structure seen at the interface for a solution of 2% wt NaAOT is a 35 ± 2 Å thick bilayer adsorbed to the sapphire surface at maximum packing density, followed by an aligned stack of fluctuating bilayers of thickness 51 ± 2 Å and with an area per molecule of 40 ± 2 Å(2). Each bilayer is separated by a water: at 25 °C, this layer is 148 ± 2 Å. A simple model for the reflectivity from fluctuating layers is presented, and for 2.0% wt NaAOT the fluctuations were found to have an amplitude of 25 ± 5 Å. The temperature sensitivity of the structure at the surface was investigated in the range 15-30 °C. The effect of temperature was pronounced, with the solvent layer becoming thinner and the volume occupied by the NaAOT molecules in a bilayer increasing with temperature. The amplitude of the fluctuations, however, is approximately temperature independent in this range. The adsorption of NaAOT at the sapphire surface resembles that previously found at hydrophilic and hydrophobic silica surfaces. The coexisting bulk lamellar phase has a spacing of layers similar to that observed at the surface. These observations are an indication that the major driving force for adsorption is self-assembly, independent of the chemical nature of the interface. PMID:21443213

  4. Low-pressure lipase-catalyzed production of mono- and diglycerides with and without N-butane and AOT surfactant.

    PubMed

    Valério, Alexsandra; Fiametti, Karina G; Rovani, Suzimara; Treichel, Helen; de Oliveira, Débora; Oliveira, J Vladimir

    2010-03-01

    The aim of this work is to report the production of mono- and diglycerides from olive oil at ambient condition and in pressurized n-butane as solvent medium. For this purpose, a commercial immobilized lipase (Novozym 435) was employed as catalyst and sodium (bis-2-ethyl-hexyl) sulfosuccinate (Aerosol-OT or AOT) as surfactant. The experiments were conducted in batch mode varying the temperature, pressure, and AOT concentration. Results showed that lipase-catalyzed glycerolysis either with compressed n-butane or in solvent-free system with AOT as surfactant might be a potential alternative route to conventional methods, as high contents of reaction products, especially monoglycerides ( approximately 60 wt.%), were achieved at mild temperature and pressure with a relatively low solvent to substrates mass ratio (4:1) in short reaction times (2 h). PMID:19641856

  5. Ultrafast energy transfer in water-AOT reverse micelles.

    PubMed

    Cringus, Dan; Bakulin, Artem; Lindner, Jörg; Vöhringer, Peter; Pshenichnikov, Maxim S; Wiersma, Douwe A

    2007-12-27

    A spectroscopic investigation of the vibrational dynamics of water in a geometrically confined environment is presented. Reverse micelles of the ternary microemulsion H2O/AOT/n-octane (AOT = bis-2-ethylhexyl sulfosuccinate or aerosol-OT) with diameters ranging from 1 to 10 nm are used as a model system for nanoscopic water droplets surrounded by a soft-matter boundary. Femtosecond nonlinear infrared spectroscopy in the OH-stretching region of H2O fully confirms the core/shell model, in which the entrapped water molecules partition onto two molecular subensembles: a bulk-like water core and a hydration layer near the ionic surfactant headgroups. These two distinct water species display different relaxation kinetics, as they do not exchange vibrational energy. The observed spectrotemporal ultrafast response exhibits a local character, indicating that the spatial confinement influences approximately one molecular layer located near the water-amphiphile boundary. The core of the encapsulated water droplet is similar in its spectroscopic properties to the bulk phase of liquid water, i.e., it does not display any true confinement effects such as droplet-size-dependent vibrational lifetimes or rotational correlation times. Unlike in bulk water, no intermolecular transfer of OH-stretching quanta occurs among the interfacial water molecules or from the hydration shell to the bulk-like core, indicating that the hydrogen bond network near the H2O/AOT interface is strongly disrupted. PMID:18047308

  6. AOT water-in-oil microemulsions as a penetration enhancer in transdermal drug delivery of 5-fluorouracil.

    PubMed

    Gupta, Reeta R; Jain, Swantrant K; Varshney, Manoj

    2005-03-10

    In vitro transdermal permeation of 5-fluorouracil (antineoplastic), a hydrophilic drug encapsulated in AOT/water/isopropylmyristate water-in-oil microemulsions (MEs), were studied using a modified Keshary and Chien diffusion cell. AOT (aerosol-OT or sodium bis(2-ethylhexyl) sulfosuccinate) is an anionic surfactant, which forms 'water-in-oil' ME in non-aqueous medium. The effect of water and AOT concentrations in MEs to the transdermal permeation of 5-fluorouracil through hairless mouse skin was investigated. MEs with 5:95 weight ratio of AOT:isopropylmyristate, containing 0.9, 1.8, 2.7 and 3.6% w/w of water have showed 1.68-, 2.36-, 3.58- and 3.77-fold increases in the skin flux of 5-fluorouracil (5-FU) respectively, compared to the aqueous solution of drug. The MEs with 5:95, 9:91 and 13:87 weight ratio of AOT:isopropyl myristate at fixed water content W0=15 (W0=[H2O]/AOT]) gave 3.58-, 5.04- and 6.3-fold enhancement of drug. In addition, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy was used to examine the effect of ME on lipid alkyl chain, hydration level, and corneocyte cells of the stratum corneum (SC). Results reveal that the ME interacts with a component of the SC and perturbs its architectural structure. The extent of perturbation in the SC depends on the concentration of water and AOT in the ME. Preliminary dermal toxicity studies indicate that the AOT/water/isopropylmyristate ME be safe for the transdermal permeation of 5-FU. PMID:15698753

  7. Liquid-crystalline and microemulsion phase behavior in alcohol-free aerosol-OT/oil/brine systems

    SciTech Connect

    Ghosh, O.; Miller, C.A.

    1987-08-13

    The phase behavior of systems containing the pure anionic surfactant Aerosol OT or sodium bis(2-ethylhexyl) sulfosuccinate was studied as a function of salt concentration, surfactant concentration, alkane carbon number, and water-to-oil ratio. Since the hydrophilic and lipophilic properties of Aerosol OT are nearly balanced, the surfactant forms microemulsions with water and oil in the absence of cosurfactant, allowing for simplified representation of phase behavior. In particular, this property aided in the understanding of transitions between the aqueous surfactant phase behavior and the well-studied oil-rich microemulsion regime. With the addition of salt to dilute alcohol-free surfactant-water mixtures, transitions in the liquid-crystalline phases similar to those seen previously for systems containing petroleum sulfonates and other anionic surfactants with alcohol cosurfactants were found. When hydrocarbons of various chain lengths were equilibrated with the aqueous surfactant solutions, again behavior similar to that of anionic surfactants with alcohol cosurfactants was observed. Pseudoternary diagrams of surfactant-brine-oil were constructed at various brine salinities with n-dodecane as the oil. The assumption that brine acts as a pseudocomponent was found to work best at salinities well below and well above the optimum and at low surfactant concentrations. In any case, the results provide extensive information on phase behavior of a four-component system containing a pure anionic surfactant, a pure hydrocarbon, and sodium chloride brine over a region of considerable interest for enhanced oil recovery and other applications.

  8. Effect of the addition of water-soluble polymers on the interfacial properties of aerosol OT vesicles.

    PubMed

    Valero, Margarita; Velázquez, M Mercedes

    2004-10-15

    The properties of the interface of vesicles of pure sodium bis-(2-ethyl-hexyl) sulfosuccinate (AOT) and binary mixtures composed of AOT with poly(ethylene) glycol (PEG), poly(sodium 4-styrensulfonate) (PSS) and sodium chloride were investigated using absorption and steady-state fluorescence of nabumetone and electrophoretic mobility measurements. Results confirm those obtained in a previous work indicating that the addition of PEG, PSS, and NaCl stabilizes the AOT vesicles. The stabilization mechanism is the screening of the surface charge in the case of binary mixtures of AOT/PSS and AOT/NaCl and the polymer adsorption on the interface for vesicles of AOT/PEG. PMID:15450468

  9. Magnetite-Alginate-AOT nanoparticles based drug delivery platform

    NASA Astrophysics Data System (ADS)

    Regmi, R.; Sudakar, C.; Dixit, A.; Naik, R.; Lawes, G.; Toti, U.; Panyam, J.; Vaishnava, P. P.

    2008-03-01

    Iron oxide having the magnetite structure is a widely used biomaterial, having applications ranging from cell separation and drug delivery to hyperthermia. In order to increase the efficacy of drug treatments, magnetite nanoparticles can be incorporated into a composite system with a surfactant-polymer nanoparticle, which can act as a platform for sustained and enhanced cellular delivery of water-soluble molecules. Here we report a composite formulation based on magnetite and Alginate-aerosol OT (AOT) nanoparticles formulated using an emulsion-cross-linking process loaded with Rhodamine 6G [1]. We prepared two set of nanoparticles by using Ca^2+ or Fe^2+ to cross-link the alginate polymer. Additionally, we added ˜8 nm diameter Fe3O4 magnetic nanoparticles prepared by a soft chemical method to these alginate-AOT nanoparticles. The resulting composites were superparamagnetic at room temperature, with a saturation magnetization of approximately 0.006 emu/g of solution. We will present detailed studies on the structural and magnetic properties of these samples. We will also discuss HPLC measurements on Rhodamine uploading in these composites. [1] M.D.Chavanpatil, Pharmaceutical Research, vol.24, (2007) 803.

  10. Temperature control of pattern formation in the Ru(bpy)(3)(2+)-catalyzed BZ-AOT system.

    PubMed

    McIlwaine, Rachel; Vanag, Vladimir K; Epstein, Irving R

    2009-03-14

    Using temperature as a control parameter, we observe a transition from stationary Turing patterns at T = 15-20 degrees C to traveling waves at T = 50 degrees C (and above) in the Ru(bpy)(3)(2+)-catalyzed Belousov-Zhabotinsky (BZ) reaction incorporated into the water nanodroplets of a water-in-oil aerosol OT (AOT) microemulsion. At constant chemical composition, molar ratio and droplet fraction, the transition takes place via a series of stable patterns, including oscillatory Turing patterns (at 35-40 degrees C) and reversed oscillatory Turing patterns (at 50 degrees C). We attribute the pattern transitions to a temperature-induced percolation transition of the BZ-AOT microemulsion, implying a change from isolated water nanodroplets to a system-spanning network of water channels. PMID:19240935

  11. Perovskite LaFeO3 nanoparticles synthesized by the reverse microemulsion nanoreactors in the presence of aerosol-OT: Morphology, crystal structure, and their optical properties

    NASA Astrophysics Data System (ADS)

    Abazari, Reza; Sanati, Soheila

    2013-12-01

    Orthorhombic structure of lanthanum ferrite nanoparticles (LaFeO3 NPs) with perovskite type phase has been synthesized with water-in-oil (W/O) microemulsion consisted of water/dioctyl sulfosuccinate sodium (aerosol-OT)/isooctane at room temperature. It has been shown that aerosol-OT reverse microemulsion solution is appropriate for synthesizing perovskite LaFeO3 NPs in the absence of any co-surfactants. Field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), energy dispersive analysis of X-ray (EDAX), X-ray diffraction (XRD), ultraviolet-visible absorption spectroscopy (UV-Vis), and Fourier transform infrared spectroscopy (FT-IR) have been adopted for characterization of surface morphology, size, phase composition, structure, and optical properties of the considered NPs. Furthermore, the optical properties of LaFeO3 NPs have been further analyzed via photoluminescence (PL) spectroscopy. As shown by the physicochemical characterizations, our prepared NPs via aerosol-OT reverse microemulsion solution are spherical and nearly uniform (with a size of about 24.65 nm). Besides, they include an orthorhombic phase while no impurities are observed. Single phase lanthanum ferrite NPs have successfully been prepared at 500 °C. Moreover, UV-Vis spectrum indicates that the LaFeO3 NPs synthesized through this technique can be considered as a type of photo-catalytic materials.

  12. Electronic excited-state behavior of rhodamine 3B in AOT reverse micelles sensing contact ion pair to solvent separated ion pair interconversion.

    PubMed

    Ferreira, José A B; Costa, Sílvia M B

    2010-08-19

    The amphiphile Aerosol OT (1,4-bis(2-ethylhexyl)sodium sulfosuccinate, AOT) forms, in reverse micellar nanoaggregates of water, RM, in isooctane, ion pairs (IPs) with the cationic fluorescent probe dye, rhodamine 3B, (3,6-bis(ethylamino)-9-[2-(ethoxycarbonyl)phenyl]-9H-xanthen-9-ylium, R3B), as either contact ion pairs, CIPs, or solvent (water) separated ion pairs, SSIPs. The ground-state AOT R3B ion pairs' equilibria as well as the dynamics of R3B electronic excited states show the progressive hydration of AOT(-) R3B(+) toward solvent separated ion pairs, SSIPs as the characteristic reverse micelle parameter w(0) = [H(2)O]/[AOT] increases. The apparent limiting hydration constant of R3B ion pairs, K(hyd) = 2.8 +/- 0.2, corresponds to full hydration of AOT, consistent with 1-3 water molecules per AOT polar head. Transient relaxations at w(0) = 0.2, with a 375 +/- 15 ps decay at 550 nm decrease to 115 +/- 15 ps at w(0) = 7.2 turning into corresponding rises at 588 nm. At higher w(0), water induced dynamics becomes faster. The lifetime is longer in RM with smaller w(0), due to the presence of CIPs that inhibit intrinsic nonradiative decay processes, which in contrast shorten the decay times at higher w(0), due to the presence of SSIPs. The pairs' electronic excited-state properties are sensitive to viscosity and local polarity of the surrounding environment of the interfacial regions of AOT reverse micellar nanoaggregates. PMID:20666438

  13. Correlation between AERONET AOT and VIIRS EDR AOT: A new EDR cell

    NASA Astrophysics Data System (ADS)

    Molinie, J.; Henry, J. L.; Clement, J.; Euphrasie-Clotilde, L.; Brute, F. N.

    2015-12-01

    Every year, a huge mass of desert dusts lifted from Saharan and sub Saharan regions is injected over the Atlantic Ocean and bring to the Caribbean and the American continent. Guadeloupe a West Indies island, is affected by the presence of dusts particles which impact the air quality and acts on human health. The effect produced by the particles in the atmosphere can be observed by satellite. VIIRS is one the latest tools provided by NASA, to help scientific community to have a better understanding of aerosol behavior. In this job we try to found a link between ground measurement AOT and VIIRS data.In Guadeloupe, AOT measurements have been performed with sun photometer of AERONET network. We calculated AOT at 500 nm mean daily sun photometer data in order to compare them with AOT EDR 550 data computed by NOAA Aerosol calibration and validation team. Three AOT EDR cells, located over the ocean and close to the East coast of the island of have been chosen to evaluate the correlation between ground and satellite data. We obtained using data performed from May to December 2012, correlation coefficient range between 0.8 and 0.87. We observed numerous AOT EDR 550 have been computed with a number of IP pixel, nAOT very low. We proposed to used only cases with nAOT equal or higher than 10. The correlation coefficients improved and reached 0.9. However, those good results have been obtained with a day number reduced by almost 50 per cent.In order to keep a good correlation and a higher number of day we rebuilt a cell by merging two cells. We obtained a new cell with an AOT EDR value equal to the mean AOT EDR of the two parents' value and a nAOT the sum of the previous nAOTs. The results with the new nAOT equal of higher than 10 is, r =0.91 and we keep 75 per cent of the cases.

  14. Trend estimates of AERONET-observed and model-simulated AOT percentiles between 1993 and 2013

    NASA Astrophysics Data System (ADS)

    Yoon, Jongmin; Pozzer, Andrea; Chang, Dong Yeong; Lelieveld, Jos

    2016-04-01

    Recent Aerosol Optical thickness (AOT) trend studies used monthly or annual arithmetic means that discard details of the generally right-skewed AOT distributions. Potentially, such results can be biased by extreme values (including outliers). This study additionally uses percentiles (i.e., the lowest 5%, 25%, 50%, 75% and 95% of the monthly cumulative distributions fitted to Aerosol Robotic Network (AERONET)-observed and ECHAM/MESSy Atmospheric Chemistry (EMAC)-model simulated AOTs) that are less affected by outliers caused by measurement error, cloud contamination and occasional extreme aerosol events. Since the limited statistical representativeness of monthly percentiles and means can lead to bias, this study adopts the number of observations as a weighting factor, which improves the statistical robustness of trend estimates. By analyzing the aerosol composition of AERONET-observed and EMAC-simulated AOTs in selected regions of interest, we distinguish the dominant aerosol types and investigate the causes of regional AOT trends. The simulated and observed trends are generally consistent with a high correlation coefficient (R = 0.89) and small bias (slope±2σ = 0.75 ± 0.19). A significant decrease in EMAC-decomposed AOTs by water-soluble compounds and black carbon is found over the USA and the EU due to environmental regulation. In particular, a clear reversal in the AERONET AOT trend percentiles is found over the USA, probably related to the AOT diurnal cycle and the frequency of wildfires.

  15. 1H NMR studies of aerosol-OT reverse micelles with alkali and magnesium counterions: preparation and analysis of MAOTs.

    PubMed

    Stahla, Michelle L; Baruah, Bharat; James, Dustin M; Johnson, Michael D; Levinger, Nancy E; Crans, Debbie C

    2008-06-17

    Simple procedures and characterization of a series of well-defined precursors are described for preparation of a unique microenvironment in nanoreactors, reverse micelles. The Na(+), K(+), Rb(+), Cs(+), and Mg(2+) surfactants were prepared using liquid-liquid ion exchange using chloride and nitrate salts. The surfactants were characterized using (1)H NMR spectroscopy and a variety of other techniques. (1)H NMR spectroscopy was found to be a sensitive probe for characterization of the size of the nanoreactor as well as its water content. (1)H NMR spectra can be used for detailed characterization of reactions in confined environments when counterion effects are likely to be important. (1)H NMR spectroscopy revealed two separate peaks corresponding to water in Mg(AOT)2 samples; one peak arises from water coordinated to the Mg(2+) ion while the other peak arises from bulk water. The two water signals arise directly from the slow exchange of the water coordinated to Mg(2+) in these microemulsions with water in the water pool, and provide an opportunity to study hydration of Mg(2+). This work thus extends the potential use of MAOT microemulsions for applications such as in green chemistry. PMID:18484757

  16. High static pressure alters water-pool properties in reversed micelles formed by aerosol OT (sodium bis(2-ethylhexyl)sulfosuccinate): A high pressure ESR study

    NASA Astrophysics Data System (ADS)

    Sueishi, Yoshimi; Yoshioka, Daisuke; Negi, Mieko; Kotake, Yashige

    2005-11-01

    ESR spectra of Fremy's salt in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reversed micelles were recorded at high pressures in order to monitor dynamic properties of water molecules inside water pools. Rotational correlation times of Fremy's salt in large AOT water pools slightly decreased with increasing pressure, conversely those in small water pools increased with pressure: Δ V‡ for the rotational motion = -1.05 and 9.19 cm 3 mol -1 at ω0 = 20 and 2, respectively. These results demonstrate that most water molecules in small water pools are bound to AOT head groups and show very different physical properties from bulk water.

  17. Effect of confinement on excited-state proton transfer of firefly's chromophore D-luciferin in AOT reverse micelles.

    PubMed

    Kuchlyan, Jagannath; Banik, Debasis; Kundu, Niloy; Ghosh, Surajit; Banerjee, Chiranjib; Sarkar, Nilmoni

    2014-03-27

    Excited-state intermolecular proton transfer of D-luciferin in reverse micelles has been investigated using steady-state and time-resolved fluorescence spectroscopy measurement. The different polar cores have been chosen for the study of proton transfer dynamics in aerosol-OT (AOT) reverse micelles. It is shown that aqueous reverse micelle is the suitable environment for the photoprotolytic reaction of D-luciferin. The neutral form of the chromophore is present both in ground and excited state at W0 = 0. The proton transfer in nanometer size water pool of water/AOT/n-heptane begins at W0 = 8 and increases with increasing W0 values. However, the intermolecular excited-state proton transfer (ESPT) of D-luciferin is inhibited in nonaquous reverse micelles with DMF and DMSO as a polar core. Thus, the requirement of ESPT of D-luciferin to take place in reverse micelles consists of polar protic solvent like water as a polar core. PMID:24624892

  18. Trend estimates of AERONET-observed and model-simulated AOTs between 1993 and 2013

    NASA Astrophysics Data System (ADS)

    Yoon, J.; Pozzer, A.; Chang, D. Y.; Lelieveld, J.; Kim, J.; Kim, M.; Lee, Y. G.; Koo, J.-H.; Lee, J.; Moon, K. J.

    2016-01-01

    Recently, temporal changes in Aerosol Optical Thickness (AOT) have been investigated based on model simulations, satellite and ground-based observations. Most AOT trend studies used monthly or annual arithmetic means that discard details of the generally right-skewed AOT distributions. Potentially, such results can be biased by extreme values (including outliers). This study additionally uses percentiles (i.e., the lowest 5%, 25%, 50%, 75% and 95% of the monthly cumulative distributions fitted to Aerosol Robotic Network (AERONET)-observed and ECHAM/MESSy Atmospheric Chemistry (EMAC)-model simulated AOTs) that are less affected by outliers caused by measurement error, cloud contamination and occasional extreme aerosol events. Since the limited statistical representativeness of monthly percentiles and means can lead to bias, this study adopts the number of observations as a weighting factor, which improves the statistical robustness of trend estimates. By analyzing the aerosol composition of AERONET-observed and EMAC-simulated AOTs in selected regions of interest, we distinguish the dominant aerosol types and investigate the causes of regional AOT trends. The simulated and observed trends are generally consistent with a high correlation coefficient (R = 0.89) and small bias (slope±2σ = 0.75 ± 0.19). A significant decrease in EMAC-decomposed AOTs by water-soluble compounds and black carbon is found over the USA and the EU due to environmental regulation. In particular, a clear reversal in the AERONET AOT trend percentiles is found over the USA, probably related to the AOT diurnal cycle and the frequency of wildfires. In most of the selected regions of interest, EMAC-simulated trends are mainly attributed to the significant changes of the dominant aerosols; e.g., significant decrease in sea salt and water soluble compounds over Central America, increase in dust over Northern Africa and Middle East, and decrease in black carbon and organic carbon over Australia.

  19. Trend Estimates of AERONET-Observed and Model-Simulated AOTs Between 1993 and 2013

    NASA Technical Reports Server (NTRS)

    Yoon, J.; Pozzer, A.; Chang, D. Y.; Lelieveld, J.; Kim, J.; Kim, M.; Lee, Y. G.; Koo, J.-H.; Lee, J.; Moon, K. J.

    2015-01-01

    Recently, temporal changes in Aerosol Optical Thickness (AOT) have been investigated based on model simulations, satellite and ground-based observations. Most AOT trend studies used monthly or annual arithmetic means that discard details of the generally right-skewed AOT distributions. Potentially, such results can be biased by extreme values (including outliers). This study additionally uses percentiles (i.e., the lowest 5%, 25%, 50%, 75% and 95% of the monthly cumulative distributions fitted to Aerosol Robotic Network (AERONET)-observed and ECHAM/MESSy Atmospheric Chemistry (EMAC)-model simulated AOTs) that are less affected by outliers caused by measurement error, cloud contamination and occasional extreme aerosol events. Since the limited statistical representativeness of monthly percentiles and means can lead to bias, this study adopts the number of observations as a weighting factor, which improves the statistical robustness of trend estimates. By analyzing the aerosol composition of AERONET-observed and EMAC-simulated AOTs in selected regions of interest, we distinguish the dominant aerosol types and investigate the causes of regional AOT trends. The simulated and observed trends are generally consistent with a high correlation coefficient (R = 0.89) and small bias (slope+/-2(sigma) = 0.75 +/- 0.19). A significant decrease in EMAC-decomposed AOTs by water-soluble compounds and black carbon is found over the USA and the EU due to environmental regulation. In particular, a clear reversal in the AERONET AOT trend percentiles is found over the USA, probably related to the AOT diurnal cycle and the frequency of wildfires. In most of the selected regions of interest, EMAC-simulated trends are mainly attributed to the significant changes of the dominant aerosols; e.g., significant decrease in sea salt and water soluble compounds over Central America, increase in dust over Northern Africa and Middle East, and decrease in black carbon and organic carbon over

  20. Enhanced stabilization of aerosol-OT surfactant monolayer upon interaction with small amounts of bovine serum albumin at the air-water interface.

    PubMed

    Caetano, Wilker; Ferreira, Marystela; Oliveira, Osvaldo N; Itri, Rosangela

    2004-10-10

    An investigation is made of the influence from small amounts of the protein bovine serum albumin (BSA) on the lateral organization of low molecular weight surfactant sodium bis-2-ethylhexyl sulfosuccinate (AOT) at the air-water interface. Surface pressure (pi - A), surface potential (deltaV - A) and Brewster angle microscopy (BAM) experiments were carried out, with particular emphasis on the monolayer stability under successive compression-expansion cycles. AOT monolayer is not stable at the air-water interface, which means that the majority of AOT molecules go into the aqueous subphase as monomers and/or normal micelles. When a waiting time elapses between spreading and compression, the surfactant monolayer tends to reorganize partially at the air-water interface, with a monolayer expansion being observed for waiting times as large as 12 h. The incorporation of very small amount of BSA (10(-9)M) at the interface, also inferred from BAM, increases the monolayer stability as revealed by pi - A and deltaV - A results. For a waiting time of circa 3 h, the mixed monolayer reaches its maximum stability. This must be related to protein (and/or protein-surfactant complexes) adsorbed onto the AOT monolayer, thus altering the BSA conformation to accommodate its hydrophobic/hydrophilic residues. Furthermore, the effects from such small amounts of BSA in the monolayer formation and stabilization mean that the AOT monolayer responds cooperatively to BSA. PMID:15465300

  1. Aerosol-OT in water forms fully-branched cylindrical direct micelles in the presence of the ionic liquid 1-butyl-3-methylimidazolium bromide.

    PubMed

    Murgia, Sergio; Palazzo, Gerardo; Mamusa, Marianna; Lampis, Sandrina; Monduzzi, Maura

    2011-05-28

    A recent investigation on the sodium bis(2-ethylhexyl)sulfosuccinate/water/1-butyl-3-methylimidazolium tetrafluoborate (NaAOT/W/bmimBF(4)) system showed that the anionic two-tailed surfactant NaAOT, that is known to form reverse micelles or planar interfaces (typically lamellar liquid crystals), can originate discrete spherical micelles of normal curvature because of strong interactions with the ionic liquid. The goal of the present paper was to detect macro- and microscopic modifications within such a system upon substitution of the ionic liquid's counter-ion tetrafluoroborate with bromide. Firstly, the phase diagram of the NaAOT/water/bmimBr system was determined. Then, the monophasic regions were investigated by means of NMR self-diffusion and SAXRD experiments. The results obtained proved this system to be surprisingly different from that containing bmimBF(4). This study focused mainly on the characterization of the micellar region, which turned out to be constituted of a bicontinuous nanostructure. This finding can be accounted for suggesting a decreasing of the NaAOT effective surfactant packing parameter, as in the case of NaAOT/water/bmimBF(4) system, although the effect in the presence of Br(-) is less pronounced. Data modeling showed the same degree of interfacial adsorption for the bmim(+) cation in both systems, regardless of the particular counterion used-either BF(4)(-) or Br(-). Thus, the remarkable differences between the two systems appear to be mainly due to a specific counterion effect. This result highlights once again the ions specificity, which is found ubiquitously in chemistry and biology. PMID:21468445

  2. Electrochemistry and electrocatalysis with vitamin B sub 12 in an AOT water-in-oil microemulsion

    SciTech Connect

    Owlia, Azita; Wang, Zhenghao; Rusling, J.F. )

    1989-07-05

    Vitamin B{sub 12a} solubilized in water pools of highly resistive water-in-oil (w/o) microemulsions of 0.2 M Aerosol OT (AOT, bis(2-ethylhexyl) sulfosuccinate)/4 M water/isooctane gave separate reductions of base-on cob(III)alamine to base-on cob(II)alamine (E{sub 1/2} = {minus}0.03 V vs SCE) and base-on cob(II)alamine to base-off cob(I)alamine (E{sub 1/2} = {minus} 0.87 V). Diffusion coefficients suggested that vitamin B{sub 12} induces the formation of surfactant aggregates in w/o microemulsions that are larger than in solute-free systems. Relative reactivities toward reductions of three oil-soluble alkyl vicinal dihalides by electrochemically generated cob(I) alamine were modified in the microemulsion compared to isotropic water-acetonitrile. Changes in relative reactivity are not explained by simple partition of vicinal dibromides between isooctane and water and suggest specific interactions with surfactant aggregates or significant reaction in the bulk isooctane phase.

  3. Unexpected increasing AOT trends over northwest Bay of Bengal in the early postmonsoon season

    SciTech Connect

    Kishcha, P.; Starobinets, B.; Long, Charles N.; Alpert, P.

    2012-12-13

    The main point of our study is that aerosol trends can be created by changes in meteorology without changes in aerosol source strength. Over the 10 year period 2000–2009, in October, Moderate Resolution Imaging Spectroradiometer (MODIS) showed strong increasing aerosol optical thickness (AOT) trends of approximately 14% yr-1 over northwest Bay of Bengal (BoB) in the absence of AOT trends over the east of the Indian subcontinent. This was unexpected because sources of anthropogenic pollution were located over the Indian subcontinent and aerosol transport from the Indian subcontinent to northwest BoB was carried out by prevailing winds. In October, winds over the east of the Indian subcontinent were stronger than winds over northwest BoB, which resulted in wind convergence and accumulation of aerosol particles over northwest BoB. Moreover, there was an increasing trend in wind convergence over northwest BoB. This led to increasing trends in the accumulation of aerosol particles over northwest BoB and, consequently, to strong AOT trends over this area. In contrast to October, November showed no increasing AOT trends over northwest BoB or the nearby Indian subcontinent. The lack of AOT trends over northwest BoB corresponds to a lack of trends in wind convergence in that region. Finally, December domestic heating by the growing population resulted in positive AOT trends of similar magnitude over land and sea. Our findings illustrate that in order to explain and predict trends in regional aerosol loading, meteorological trends should be taken into consideration together with changes in aerosol source strength.

  4. Trend estimates of AERONET-observed and model-simulated AOTs between 1993 and 2013

    NASA Astrophysics Data System (ADS)

    Yoon, Jongmin; Pozzer, Andrea; Chang, Dong Yeong

    2015-04-01

    Recently, several researches have been actively conducted on the temporal changes in global aerosol by model simulations and satellite/ground observations. However, most studies of the trend estimates were based on monthly arithmetic means that are not good enough to present measures of central tendency in generally right-skewed AOT distributions. Therefore their results can be biased by the extreme values (i.e. outliers). This study uses several percentiles (i.e. the lowest 5%, 25%, 50%, 75%, and 95% in monthly cumulative distributions of the Aerosol Robotic Network (AERONET) all-points L2.0 data) that are less sensitive to the outliers, and provides the trend estimates to be more statistically robust. By applying various aerosol type classifications based on Ångström exponent, Single scattering albedo, and fine-mode fraction, we investigate the causes leading to the AOT trends over different regions. Furthermore, we minimize the possible uncertainty in the trend estimates regarding the underrepresented aerosols below clouds by integrating the model-simulated AOT from EMAC (ECHAM5/MESSy for Atmospheric Chemistry). In addition, the trend estimates of EMAC-simulated AOTs decomposed into several aerosol components (i.e., black carbon, organic carbon, dust, aerosol water, sea salt, and water soluble compounds) are potentially useful to identify the leading causes.

  5. Master: 3 OT

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Lipunov, V.; Buckley, D.; Tlatov, A.; Gorbovskoy, E.; Tyurina, N.; Kuznetsov, A.; Kornilov, V.; Kuvshinov, D.; Popova, E.; Vlasenko, D.; Shumkov, V.; Potter, S.; Kniazev, A.; Budnev, N.; Gress, O.; Ivanov, K.; Senik, V.; Dormidontov, D.; Parhomenko, A. V.

    2016-08-01

    MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 21h 33m 50.58s +06d 51m 22.5s on 2016-07-27.94690 UT. The OT unfiltered magnitude is 17.8m (limit 18.0m).

  6. MASTER: bright OTs

    NASA Astrophysics Data System (ADS)

    Gress, O.; Vladimirov, V.; Lipunov, V.; Gorbovskoy, E.; Buckley, D.; Balanutsa, P.; Tiurina, N.; Kornilov, V.; Kuznetsov, A.; Gorbunov, I.; Vlasenko, D.; Kuvshinov, D.; Popova, E.; Potter, S.; Kotze, M.; Budnev, N.; Poleschuk, V.; Ivanov, K.

    2016-01-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 14h 50m 56.15s -25d 55m 26.9s on 2016-01-27.02773 UT. The OT unfiltered magnitude is 16.3 (limit 18.4m).

  7. Relationship between Column AOT and Surface PM2.5 over the U.S.

    NASA Technical Reports Server (NTRS)

    Chin, Mian

    2004-01-01

    The quantitative use of the satellite observations of aerosol for local air quality forecast/study will be explored by examining the relationship between the column Aerosol Optical Thickness (AOT) and the surface PM2.5 at different locations and seasons over the U.S. We use the global model GOCART, the MODIS satellite data, and the EPA surface measurements to demonstrate the feasibility of satellite data application for air quality study.

  8. The influence of the structure and the composition of water/AOT-Tween 85/IPM microemulsion system on transdermal delivery of 5-fluorouracil.

    PubMed

    Yanyu, Xiao; Fang, Liu; Qineng, Ping; Hao, Cai

    2012-12-01

    The purpose of this study was to investigate the influence of the structure and the composition of water/Aerosol-OT (AOT)-Tween 85/isopropylmyristate (IPM) microemulsion system (WATI) on transdermal delivery of 5-fluorouracil (5-FU). The structure of WATI was characterized by measuring surface tension, density, viscosity, electric conductivity, and differential scanning calorimetry. The effect of the drug loading, water content, component compositions and the amount of mixed surfactant on permeation of 5-FU through mice skin was evaluated by using Franz-type diffusion cells. The results in vitro implied that WATI was W/O microemulsion when the water content was below 20 wt% at fixed 20 wt% of mixed surfactant at 25°C, then might be transformed to a bicontinuous structure, finally, formed O/W microemulsion with water content over 30 wt%. Increase of the drug loading can directly facilitate the penetration of the drug across the skin. Drug diffusion after 12 h from the bicontinuous microemulsion (795.1 ± 22.3 µg·cm(-2)) would be fastest compared to that from the W/O microemulsion (650.2 ± 11.7 µg·cm(-2)) and the O/W microemulsion (676.6 ± 14.8 µg·cm(-2)). The combination of AOT and IPM could bring about synergistic effect on the skin enhancement, however, Tween 85 in WATI decreased the cumulative permeation amount of 5-FU. The content of mixed surfactant had no effect on the permeation of 5-FU at fixed surfactant/cosurfactant ratio (K(m) = 2). Thus, the increased transdermal delivery the hydrophilic drug of 5-FU was found to be concerned with both of the structure and the composition of WATI. PMID:22324326

  9. Short term variability of aerosol optical thickness at Belsk for the period 2002-2010

    NASA Astrophysics Data System (ADS)

    Pietruczuk, Aleksander

    2013-11-01

    In this work variability of aerosol optical thickness (AOT) measured at Belsk, Poland is studied as well as modification of AOT during airmass advection towards Belsk. AOT measurements taken at Belsk and at AERONET stations located in eastern Germany, Belarus and Scandinavia are used as well as satellite measurements of AOT taken by MODIS instrument onboard Terra and Aqua satellites. Directions of airmass advection are determined by means of cluster analysis of airmass backward-trajectories. Changes of AOT at Belsk from day to day varies around zero regardless of time lag between measurements. The standard deviation of these measurements increases with increasing time lag. In case of advection from west and north direction such standard deviation is reduced. It gives good perspective for a persistent forecast of next day AOT. Analysis of AOT changes during airmass advection toward Belsk reveals two modes of AOT changes distributions. One of them with small increase of AOT and second one with larger increase of AOT, so-called loading mode. Loading mode dominates in case of advection from south direction whilst the first mode of AOT changes dominates in case of advection from other directions. Mean increase of AOT associated with the first mode is 0.034 ± 0.003. Analysis of backward-trajectories shows that aerosol loading occurs over urban/industrial regions located south and south-west of Belsk. Substantial aerosol loading is found during seasonal biomass burning episodes in Eastern Europe.

  10. Characteristics of spontaneously formed nanoemulsions in octane/AOT/brine systems.

    PubMed

    Kini, Gautam C; Biswal, Sibani Lisa; Wong, Michael S; Miller, Clarence A

    2012-11-01

    Nanoemulsions were formed spontaneously by diluting water-in-oil (W/O) or brine-in-oil (B/O) microemulsions of a hydrocarbon (octane), anionic surfactant (Aerosol-OT or AOT) and water or NaCl brine in varying levels of excess brine. The water-continuous nanoemulsions were characterized by interfacial tension, dynamic light scattering, electrophoresis, optical microscopy and phase-behavior studies. The mechanism of emulsification was local supersaturation and resulting nucleation of oil during inversion. For nanoemulsions formed at low salinities with Winsor I phase behavior, octane drops grew from initial diameters of 150-250 nm to 480-1000 nm over 24h, depending on salinity. Growth was caused by mass transfer but seemed to approach the asymptotic stage of Ostwald ripening described by the Lifshitz-Slyozov-Wagner (LSW) theory only for dilution with salt-free water. Near the higher cross-over salinity (Winsor III), the nanoemulsions showed much slower growth with droplet size consistently remaining below 200 nm over 24h and reaching 250 nm after 1 week. Birefringence indicated the presence of liquid crystal for these conditions, which could have contributed to the slow growth rate. At even higher salinity levels in the Winsor II domain, W/O/W multiple emulsions having drops greater than 1 μm in diameter were consistently recorded for the first 5-7h, after which size decreased to values below 1 μm. The number and size of internal water droplets in multiple emulsion drops was found to decrease over time, suggesting coalescence of internal droplets with the continuous water phase and mass transfer of water from internal droplets to continuous phase as possible mechanisms of the observed drop shrinkage. Electrophoresis studies showed the nanoemulsions to be highly negatively charged (zeta potentials of -60 mV to -120 mV). The high charge on octane droplets helped assure stability to flocculation and coalescence, thereby allowing mass transfer to control growth in the

  11. [An Improved DDV Method to Retrieve AOT for HJ CCD Image in Typical Mountainous Areas].

    PubMed

    Zhao, Zhi-qiang; Li, Ai-nong; Bian, Jin-hu; Huang, Cheng-quan

    2015-06-01

    Domestic HJ CCD imaging applications in environment and disaster monitoring and prediction has great potential. But, HJ CCD image lack of Mid-Nir band can not directly retrieve Aerosol Optical Thickness (AOT) by the traditional Dark Dense Vegetation (DDV) method, and the mountain AOT changes in space-time dramatically affected by the mountain environment, which reduces the accuracy of atmospheric correction. Based on wide distribution of mountainous dark dense forest, the red band histogram threshold method was introduced to identify the mountainous DDV pixels. Subsequently, the AOT of DDV pixels were retrieved by lookup table constructed by 6S radiative transfer model with assumption of constant ratio between surface reflectance in red and blue bands, and then were interpolated to whole image. MODIS aerosol product and the retrieved AOT by the proposed algorithm had very good consistency in spatial distribution, and HJ CCD image was more suitable for the remote sensing monitoring of aerosol in mountain areas, which had higher spatial resolution. Their fitting curve of scatterplot was y = 0.828 6x-0.01 and R2 was 0.984 3 respectively. Which indicate the improved DDV method can effectively retrieve AOT, and its precision can satisfy the atmospheric correction and terrain radiation correction for Hj CCD image in mountainous areas. The improvement of traditional DDV method can effectively solve the insufficient information problem of the HJ CCD image which have only visible light and near infrared band, when solving radiative transfer equation. Meanwhile, the improved method fully considered the influence of mountainous terrain environment. It lays a solid foundation for the HJ CCD image atmospheric correction in the mountainous areas, and offers the possibility for its automated processing. In addition, the red band histogram threshold method was better than NDVI method to identify mountain DDV pixels. And, the lookup table and ratio between surface reflectance

  12. Trend Analysis of global AOT based on various Polar Orbiting Satellite Observations: MODIS (Terra), MISR (Terra), SeaWiFS (OrbView-2), and MODIS (Aqua)

    NASA Astrophysics Data System (ADS)

    Yoon, J.; Vountas, M.; von Hoyningen-Huene, W.; Chang, D. Y.; Burrows, J. P.

    2012-04-01

    Many studies have investigated temporal trends of cloud-free AOTs derived from polar orbiting satellite observations since aerosol retrieval accuracy has been improved substantially. However, only few studies have discussed the fundamental limitation of incomplete sampling originated from frequent cloud disturbance and restricted temporal coverage. Furthermore, the AOT trends derived from various polar orbiting satellite observations are hardly comparable due to different sensor calibration, retrieval accuracy, and cloud screening. Therefore, the present paper integrates various analyses of AOT trends derived from multiple observations (i.e. MODIS-Terra (MOD) from 2000/03 to 2009/12, MISR-Terra (MIS) from 2000/03 to 2010/12, SeaWiFS-OrbView-2 (SEA) from 1998/01 to 2007/12, and MODIS-Aqua (MYD) from 2003/01 to 2008/12) using a weighted least squares regression in order to minimize the above mentioned issues. With high statistical confidence, the weighted trends of MOD AOT (550 nm), MIS AOT (558 nm), SEA AOT (510 nm), and MYD AOT (550 nm) over OECD Europe showed a significant decrease (-0.00274±0.00126, -0.00303±0.00169, -0.00077±0.00044, and -0.00530±0.00304 per year respectively) while increasing over East Asia (+0.00727±0.00385, +0.00673±0.00401, +0.00342±0.00171, and +0.01939±0.00986 per year respectively).

  13. Aerosol optical thickness from Brewer spectrophotometers and an investigation into the stray-light effect.

    PubMed

    Silva, Abel A; Kirchhoff, Volker W J H

    2004-04-20

    The Langley method has been applied to the measurements of direct solar radiation made by Brewer spectrophotometers to obtain the aerosol optical thickness (AOT) of the atmosphere in the ultraviolet-B range. In several cases the AOT increased with wavelength, which raises suspicion about the stray-light effect. To investigate the quality of the AOT measurements and the possibility of stray light, we conducted a campaign by using single- and double-monochromator Brewers. The campaign's results have shown that both Brewers' AOT values are in good agreement and that stray light is not an important effect for AOT at wavelengths above 306 nm. PMID:15119618

  14. Description and validation of an AOT product over land at the 0.6 μm channel of the SEVIRI sensor onboard MSG

    NASA Astrophysics Data System (ADS)

    Bernard, E.; Moulin, C.; Ramon, D.; Jolivet, D.; Riedi, J.; Nicolas, J.-M.

    2011-11-01

    The Spinning Enhanced Visible and InfraRed Imager (SEVIRI) aboard Meteosat Second Generation (MSG) launched in 2003 by EUMETSAT is dedicated to the Nowcasting applications and Numerical Weather Prediction and to the provision of observations for climate monitoring and research. We use the data in visible and near infrared (NIR) channels to derive the aerosol optical thickness (AOT) over land. The algorithm is based on the assumption that the top of the atmosphere (TOA) reflectance increases with the aerosol load. This is a reasonable assumption except in case of absorbing aerosols above bright surfaces. We assume that the minimum in a 14-days time series of the TOA reflectance is, once corrected from gaseous scattering and absorption, representative of the surface reflectance. The AOT and the aerosol model (a set of 5 models is used), are retrieved by matching the simulated TOA reflectance with the TOA reflectances measured by SEVIRI in its visible and NIR spectral bands. The high temporal resolution of the data acquisition by SEVIRI allows to retrieve the AOT every 15 min with a spatial resolution of 3 km at sub-satellite point, over the entire SEVIRI disk covering Europe, Africa and part of South America. The resulting AOT, a level 2 product at the native temporal and spatial SEVIRI resolutions, is presented and evaluated in this paper. The AOT has been validated using ground based measurements from AErosol RObotic NETwork (AERONET), a sun-photometer network, focusing over Europe for 3 months in 2006. The SEVIRI estimates correlate well with the AERONET measurements, r = 0.64, with a slight overestimate, bias = -0.017. The sources of errors are mainly the cloud contamination and the bad estimation of the surface reflectance. The temporal evolutions exhibited by both datasets show very good agreement which allows to conclude that the AOT Level 2 product from SEVIRI can be used to quantify the aerosol content and to monitor its daily evolution with a high temporal

  15. Autoregressive spatially varying coefficients model for predicting daily PM2.5 using VIIRS satellite AOT

    NASA Astrophysics Data System (ADS)

    Schliep, E. M.; Gelfand, A. E.; Holland, D. M.

    2015-12-01

    There is considerable demand for accurate air quality information in human health analyses. The sparsity of ground monitoring stations across the United States motivates the need for advanced statistical models to predict air quality metrics, such as PM2.5, at unobserved sites. Remote sensing technologies have the potential to expand our knowledge of PM2.5 spatial patterns beyond what we can predict from current PM2.5 monitoring networks. Data from satellites have an additional advantage in not requiring extensive emission inventories necessary for most atmospheric models that have been used in earlier data fusion models for air pollution. Statistical models combining monitoring station data with satellite-obtained aerosol optical thickness (AOT), also referred to as aerosol optical depth (AOD), have been proposed in the literature with varying levels of success in predicting PM2.5. The benefit of using AOT is that satellites provide complete gridded spatial coverage. However, the challenges involved with using it in fusion models are (1) the correlation between the two data sources varies both in time and in space, (2) the data sources are temporally and spatially misaligned, and (3) there is extensive missingness in the monitoring data and also in the satellite data due to cloud cover. We propose a hierarchical autoregressive spatially varying coefficients model to jointly model the two data sources, which addresses the foregoing challenges. Additionally, we offer formal model comparison for competing models in terms of model fit and out of sample prediction of PM2.5. The models are applied to daily observations of PM2.5 and AOT in the summer months of 2013 across the conterminous United States. Most notably, during this time period, we find small in-sample improvement incorporating AOT into our autoregressive model but little out-of-sample predictive improvement.

  16. Retrieval of aerosol optical thickness over land from airborne polarized measurements in Tianjin and Tangshan

    NASA Astrophysics Data System (ADS)

    Wang, Han; Sun, Xiaobing; Hou, Weizhen; Chen, Cheng; Hong, Jin

    2015-03-01

    New developed sensor was called Atmosphere Multi-angle Polarization Radiometer (AMPR). It provides airborne multi-spectral, multi-angular and polarized measurements. Based on the measurements, a method to retrieve aerosol optical thickness (AOT) was developed. To reduce the ambiguity in retrieval algorithm, the key characteristics of aerosol model over East Asia are constrained. Initial surface reflectance was estimated from measurements at 1640 nm. With iteration the surface polarized reflectance tends to the real value together with AOT. Retrieved cases were selected from measurements in Tianjin. Validation between AOTs from AMPR and CE318 is encouraging. The AOTs along the track shows reasonable temporal and spatial variation.

  17. Oxidative refolding of reduced, denatured lysozyme in AOT reverse micelles.

    PubMed

    Fan, Jun-Bao; Chen, Jie; Liang, Yi

    2008-06-01

    The refolding kinetics of the reduced, denatured hen egg white lysozyme in sodium bis(2-ethylhexyl)sulfosuccinate (AOT)-isooctane-water reverse micelles at different water-to-surfactant molar ratios has been investigated by fluorescence spectroscopy and UV spectroscopy. The oxidative refolding of the confined lysozyme is biphasic in AOT reverse micelles. When the water-to-surfactant molar ratio (omega 0) is 12.6, the relative activity of encapsulated lysozyme after refolding for 24 h in AOT reverse micelles increases 46% compared with that in bulk water. Furthermore, aggregation of lysozyme at a higher concentration (0.2 mM) in AOT reverse micelles at omega 0 of 6.3 or 12.6 is not observed; in contrast, the oxidative refolding of lysozyme in bulk water must be at a lower protein concentration (5 microM) in order to avoid a serious aggregation of the protein. For comparison, we have also investigated the effect of AOT on lysozyme activity and found that the residual activity of lysozyme decreases with increasing the concentration of AOT from 1 to 5 mM. When AOT concentration is larger than 2 mM, lysozyme is almost completely inactivated by AOT and most of lysozyme activity is lost. Together, our data demonstrate that AOT reverse micelles with suitable water-to-surfactant molar ratios are favorable to the oxidative refolding of reduced, denatured lysozyme at a higher concentration, compared with bulk water. PMID:18377920

  18. A new assessment method of outdoor tobacco smoke (OTS) exposure

    NASA Astrophysics Data System (ADS)

    Cho, Hyeri; Lee, Kiyoung

    2014-04-01

    Outdoor tobacco smoke (OTS) is concerned due to potential health effects. An assessment method of OTS exposure is needed to determine effects of OTS and validate outdoor smoking policies. The objective of this study was to develop a new method to assess OTS exposure. This study was conducted at 100 bus stops including 50 centerline bus stops and 50 roadside bus stops in Seoul, Korea. Using real-time aerosol monitor, PM2.5 was measured for 30 min at each bus stop in two seasons. ‘Peak analysis' method was developed to assess short term PM2.5 exposure by OTS. The 30-min average PM2.5 exposure at each bus stop was associated with season and bus stop location but not smoking activity. The PM2.5 peak occurrence rate by the peak analysis method was significantly associated with season, bus stop location, observed smoking occurrence, and the number of buses servicing a route. The PM2.5 peak concentration was significantly associated with season, smoking occurrence, and the number of buses servicing a route. When a smoker was standing still at the bus stop, magnitude of peak concentrations were significantly higher than when the smoker walking-through the bus stop. People were exposed to high short-term PM2.5 peak levels at bus stops, and the magnitude of peak concentrations were highest when a smoker was located close to the monitor. The magnitude of peak concentration was a good indicator helped distinguish nearby OTS exposure. Further research using ‘peak analysis' is needed to measure smoking-related exposure to PM2.5 in other outdoor locations.

  19. Comparison of Multi-angle Imaging SpectroRadiometer (MISR) joint aerosol product with high-resolution model output

    NASA Astrophysics Data System (ADS)

    Kalashnikova, O.; Lee, H.; Suzuki, K.; Braverman, A. J.

    2014-12-01

    The Multi-angle Imaging SpectroRadiometer (MISR) Level 3 Joint Aerosol product (JOINT_AS) provides global, descriptive summary of MISR Level 2 aerosol optical thickness (AOT) for eight different types of aerosols at 5 x 5 degrees of horizontal resolution in each month between March 2000 and present. Using Version 22 JOINT_AS, this study analyzed characteristics of the observed AOT distributions and compared various statistical moments of aerosol optical thickness derived from JOINT_AS with the results from Nonhydrostatic Icosahedral Atmospheric Model (NICAM) simulation. Overall, marginal distributions of AOT show highly positive skewness at many grid points. Some of the large skewness values are related to the problems in MISR's retrieval algorithm. For example, the positive skewness in AOT for strongly absorbing aerosols at mid- and high latitudes in winter results from few outlier values is due to cloud contamination over a wide area. Combined AOT for multiple MISR aerosol types is comparable to the AOT for carbonaceous, sulfate aerosols and dust particles from the NICAM simulation implemented with aerosol transport processes. NICAM's carbonaceous aerosols in the Southwest Africa show good agreement with MISR's strongly absorbing aerosols. The AOT of dust particles in MISR and NICAM exhibit similar spatial patterns over the Sahara desert. The AOT of nonabsorbing aerosols in MISR well represents spatial distributions of the sulfate aerosols originating from industrial complex over the Shandong Peninsula in China. Our results indicate that MISR's AOT for each aerosol type may be useful for monitoring biomass burning, dust storms and air pollution and evaluating chemistry climate models.

  20. Gas-aerosol cycling of ammonia and nitric acid in The Netherlands

    NASA Astrophysics Data System (ADS)

    Roelofs, Geert-Jan; Derksen, Jeroen

    2010-05-01

    Atmospheric ammonia and nitric acid are present over NW Europe in large abundance. Observations made during the IMPACT measurement campaign (May 2008, Cabauw, The Netherlands) show a pronounced diurnal cycle of aerosol ammonium and nitrate on relatively dry days. Simultaneously, AERONET data show a distinct diurnal cycle in aerosol optical thickness (AOT). We used a global aerosol-climate model (ECHAM5-HAM) and a detailed aerosol-cloud column model to help analyse the observations from this period. The study shows that the diurnal cycle in AOT is partly associated with particle number concentration, with distinct peaks in the morning and evening. More important is relative humidity (RH). RH maximizes in the night and early morning, decreases during the morning and increases again in the evening. The particle wet radius, and therefore AOT, changes accordingly. In addition, the RH variability also influences chemistry associated with ammonia and nitric acid (formation of ammonium nitrate, dissolution in aerosol water), resulting in the observed diurnal cycle of aerosol ammonium and nitrate. The additional aerosol matter increases the hygroscopicity of the particles, and this leads to further swelling by water vapor condensation and a further increase of AOT. During the day, as RH decreases and the particles shrink, aerosol ammonium and nitrate are again partly expelled to the gas phase. This behaviour contributes significantly to the observed diurnal cycle in AOT, and it illustrates the complexity of using AOT as a proxy for aerosol concentrations in aerosol climate studies in the case of heavily polluted areas.

  1. Validation of an AOT product over land at the 0.6 μm channel of the SEVIRI sensor onboard MSG

    NASA Astrophysics Data System (ADS)

    Bernard, E.; Moulin, C.; Ramon, D.; Jolivet, D.; Riedi, J.; Nicolas, J. M.

    2011-05-01

    The Spinning Enhanced Visible and InfraRed Imager (SEVIRI) aboard Meteosat Second Generation (MSG) launched in 2003 by EUMETSAT is dedicated to the Nowcasting applications and Numerical Weather Prediction and to provide information for climate monitoring and research. We use the data in visible and near infrared channels to derive the Aerosol Optical Thickness (AOT) over land. The algorithm is based on the assumption that the Top Of the Atmosphere (TOA) reflectance increases with the aerosol load. This is a reasonable assumption except in case of absorbing aerosols above bright surfaces. We assume that the minimum in a 14-day time series of the TOA reflectance is, once corrected from gaseous scattering and absorption, representative of the surface reflectance. The AOT and the aerosol model (a set of 5 models are used), are retrieved by matching the simulated TOA reflectance with the TOA reflectances measured by SEVIRI in its visible and Near Infra-Red (NIR) spectral bands. The high temporal resolution of the data acquisition by SEVIRI allows to retrieve the AOT every 15 min with a spatial resolution of 3km at sub-satellite point, over the whole SEVIRI disk which covers Europe, Africa and part of South America. The resulting AOT, a Level 2 product at the same temporal and spatial resolution than SEVIRI, is presented and evaluated in this paper. The AOT has been validated using ground based measurements from AERONET, a sun-photometer network, focusing over Europe for 3 months in 2006. The SEVIRI estimates correlate well with the AERONET measurements, r = 0.64, with a slight underestimate, bias = -0.017. The sources of errors are mainly the cloud contamination and the bad estimation of the surface reflectance. The temporal evolutions exhibited by both dataset show very good agreement which allows to conclude that the AOT Level 2 product from SEVIRI can be used to quantify the aerosol content and to monitor its daily evolution with a high temporal frequency. The

  2. Multiangle Imaging Spectroradiometer (MISR) Global Aerosol Optical Depth Validation Based on 2 Years of Coincident Aerosol Robotic Network (AERONET) Observations

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.; Gaitley, Barbara J.; Martonchik, John V.; Diner, David J.; Crean, Kathleen A.; Holben, Brent

    2005-01-01

    Performance of the Multiangle Imaging Spectroradiometer (MISR) early postlaunch aerosol optical thickness (AOT) retrieval algorithm is assessed quantitatively over land and ocean by comparison with a 2-year measurement record of globally distributed AERONET Sun photometers. There are sufficient coincident observations to stratify the data set by season and expected aerosol type. In addition to reporting uncertainty envelopes, we identify trends and outliers, and investigate their likely causes, with the aim of refining algorithm performance. Overall, about 2/3 of the MISR-retrieved AOT values fall within [0.05 or 20% x AOT] of Aerosol Robotic Network (AERONET). More than a third are within [0.03 or 10% x AOT]. Correlation coefficients are highest for maritime stations (approx.0.9), and lowest for dusty sites (more than approx.0.7). Retrieved spectral slopes closely match Sun photometer values for Biomass burning and continental aerosol types. Detailed comparisons suggest that adding to the algorithm climatology more absorbing spherical particles, more realistic dust analogs, and a richer selection of multimodal aerosol mixtures would reduce the remaining discrepancies for MISR retrievals over land; in addition, refining instrument low-light-level calibration could reduce or eliminate a small but systematic offset in maritime AOT values. On the basis of cases for which current particle models are representative, a second-generation MISR aerosol retrieval algorithm incorporating these improvements could provide AOT accuracy unprecedented for a spaceborne technique.

  3. Remote sensing of aerosols in the Arctic for an evaluation of global climate model simulations

    PubMed Central

    Glantz, Paul; Bourassa, Adam; Herber, Andreas; Iversen, Trond; Karlsson, Johannes; Kirkevåg, Alf; Maturilli, Marion; Seland, Øyvind; Stebel, Kerstin; Struthers, Hamish; Tesche, Matthias; Thomason, Larry

    2014-01-01

    In this study Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua retrievals of aerosol optical thickness (AOT) at 555 nm are compared to Sun photometer measurements from Svalbard for a period of 9 years. For the 642 daily coincident measurements that were obtained, MODIS AOT generally varies within the predicted uncertainty of the retrieval over ocean (ΔAOT = ±0.03 ± 0.05 · AOT). The results from the remote sensing have been used to examine the accuracy in estimates of aerosol optical properties in the Arctic, generated by global climate models and from in situ measurements at the Zeppelin station, Svalbard. AOT simulated with the Norwegian Earth System Model/Community Atmosphere Model version 4 Oslo global climate model does not reproduce the observed seasonal variability of the Arctic aerosol. The model overestimates clear-sky AOT by nearly a factor of 2 for the background summer season, while tending to underestimate the values in the spring season. Furthermore, large differences in all-sky AOT of up to 1 order of magnitude are found for the Coupled Model Intercomparison Project phase 5 model ensemble for the spring and summer seasons. Large differences between satellite/ground-based remote sensing of AOT and AOT estimated from dry and humidified scattering coefficients are found for the subarctic marine boundary layer in summer. Key Points Remote sensing of AOT is very useful in validation of climate models PMID:25821664

  4. Comparison of Contrast Reduction based MODIS AOT estimates with AERONET measurements

    NASA Astrophysics Data System (ADS)

    Grosso, Nuno; Paronis, Dimitris

    2010-05-01

    Satellite remote sensing of aerosols offers global and seasonal coverage of aerosol distribution patterns resolving the spatial and temporal heterogeneities introduced by the existence of different sources and thus providing a more accurate and continuous quantification and characterization of the presence of aerosols in the atmosphere. Several retrieval methods have been implemented for various satellite sensors on an operational basis, providing global standard aerosol products such as Aerosol Optical Depth (AOD) and particle size related parameters. Current techniques such as dark pixel reflectance (MODIS, MERIS), multi-angle reflectance analysis (MISR, AATSR) or quantification of light polarisation by aerosols (POLDER) rely on known surface reflectance behaviours (e.g., low surface reflective bands or low sensitivity to polarised light) to separate the surface from the atmospheric signal by first modelling surface contribution. Their accuracy and has a limited application for highly reflective or heterogeneous surfaces such as urban, desert or snow covered areas. Another set of algorithms, the so-called Contrast Reduction based algorithms, might complement information given since their principle is based on the existence of a time invariant heterogeneous surface that allows AOT retrieval by measuring the contrast differences between a pair of images with similar viewing geometry. This paper presents the results of applying a contrast reduction based algorithm to a one year dateaset of MODIS images and comparing it to the AOT measurements of five European urban influenced AERONET stations (Barcelona, Cabo da Roca, Lille, Modena, Paris). Results demonstrate a high correlation (r=0.8, =0.05 and rmse=0.08) between the MODIS contrast reduction derived AOT results and the AERONET measurements, although a systematic overestimation is observed. The error analysis further shows sensitivity to observation geometry, time-lag between reference and polluted images

  5. MASTER-Kislovodsk: bright high amplitude OT

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Lipunov, V.; Gorbovskoy, E.; Tiurina, N.; Kornilov, V.; Gress, O.; Kuznetsov, A.; Gorbunov, I.; Vlasenko, D.; Vladimirov, V.; Tlatov, A.; Senik, V.; Dormidontov, D.; Parkhomenko, A.

    2016-02-01

    MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 08h 41m 40.94s +72d 27m 32.6s on 2016-02-22.89248 UT. The OT unfiltered magnitude is . The OT is seen in 3 images.

  6. Implications of Satellite Swath Width on Global Aerosol Optical Thickness Statistics

    NASA Technical Reports Server (NTRS)

    Colarco, Peter; Kahn, Ralph; Remer, Lorraine; Levy, Robert; Welton, Ellsworth

    2012-01-01

    We assess the impact of swath width on the statistics of aerosol optical thickness (AOT) retrieved by satellite as inferred from observations made by the Moderate Resolution Imaging Spectroradiometer (MODIS). We sub-sample the year 2009 MODIS data from both the Terra and Aqua spacecraft along several candidate swaths of various widths. We find that due to spatial sampling there is an uncertainty of approximately 0.01 in the global, annual mean AOT. The sub-sampled monthly mean gridded AOT are within +/- 0.01 of the full swath AOT about 20% of the time for the narrow swath sub-samples, about 30% of the time for the moderate width sub-samples, and about 45% of the time for the widest swath considered. These results suggest that future aerosol satellite missions with only a narrow swath view may not sample the true AOT distribution sufficiently to reduce significantly the uncertainty in aerosol direct forcing of climate.

  7. Diversity of Aerosol Optical Thickness in analysis and forecasting modes of the models from the International Cooperative for Aerosol Prediction Multi-Model Ensemble (ICAP-MME)

    NASA Astrophysics Data System (ADS)

    Lynch, P.

    2014-12-01

    With the emergence of global aerosol models intended for operational forecasting use at global numerical weather prediction (NWP) centers, the International Cooperative for Aerosol Prediction (ICAP) was founded in 2010. One of the objectives of ICAP is to develop a global multi-model aerosol forecasting ensemble (ICAP-MME) for operational and basic research use. To increase the accuracy of aerosol forecasts, several of the NWP centers have incorporated assimilation of satellite and/or ground-based observations of aerosol optical thickness (AOT), the most widely available and evaluated aerosol parameter. The ICAP models are independent in their underlying meteorology, as well as aerosol sources, sinks, microphysics and chemistry. The diversity of aerosol representations in the aerosol forecast models results in differences in AOT. In addition, for models that include AOT assimilations, the diversity in assimilation methodology, the observed AOT data to be assimilated, and the pre-assimilation treatments of input data also leads to differences in the AOT analyses. Drawing from members of the ICAP latest generation of quasi-operational aerosol models, five day AOT forecasts and AOT analyses are analyzed from four multi-species models which have AOT assimilations: ECMWF, JMA, NASA GSFC/GMAO, and NRL/FNMOC. For forecast mode only, we also include the dust products from NOAA NGAC, BSC, and UK Met office in our analysis leading to a total of 7 dust models. AOT at 550nm from all models are validated at regionally representative Aerosol Robotic Network (AERONET) sites and a data assimilation grade multi-satellite aerosol analysis. These analyses are also compared with the recently developed AOT reanalysis at NRL. Here we will present the basic verification characteristics of the ICAP-MME, and identify regions of diversity between model analyses and forecasts. Notably, as in many other ensemble environments, the multi model ensemble consensus mean outperforms all of the

  8. Spectrometric study on the binding of curcumin with AOT: effect of micelle-to-vesicle transition.

    PubMed

    Zhou, Haibo; Yang, Qianqian; Wang, Xiaoyong

    2014-10-15

    In this work, the role of micelle-to-vesicle transition of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in the binding, stability and antioxidant activity of curcumin has been studied using absorption and fluorescence measurements. As AOT molecules aggregate into micelles and vesicles, curcumin bound with AOT often gives higher intensities of absorption and fluorescence than that of free curcumin. The most enhanced absorption and fluorescence of curcumin induced by AOT vesicles, are attributed to the location of curcumin in their lipid bilayer. The measurement of curcumin anisotropy suggests that the bilayer of AOT vesicles provides curcumin with a more hydrophobic microenvironment than the palisade layer of AOT micelles. The binding constant (Kb) of curcumin with AOT vesicles is three times that of curcumin with AOT micelles. Moreover, AOT vesicles are found to be superior to AOT micelles for enhancing the stability and radical scavenging ability of curcumin. PMID:24837931

  9. Spectrometric study of AOT-hydrolysis reaction in water/AOT/isooctane microemulsions using phenolphthalein as a chemical probe.

    PubMed

    Mao, Shiyan; Chen, Zhiyun; Fan, Dashuang; An, Xueqin; Shen, Weiguo

    2012-01-12

    The kinetics of the alkaline hydrolysis of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) in water/AOT/isooctane microemulsions has been studied by monitoring the absorbance change of the phenolphthalein in the system with time. The apparent first-order rate constant k(obs) has been obtained and found to be dependent on both the molar ratio of water to AOT ω and the temperature. The dependences of k(obs) on ω have been analyzed by a pseudophase model which gives the true rate constants k(i) of the AOT-hydrolysis reaction on the interface and the partition coefficients K(wi) for the distribution of OH(-) between aqueous and interface pseudophases at various temperatures; the latter is almost independent of the temperature and ω. The temperature dependences of the reaction rate constants k(obs) and k(i) have been analyzed to obtain enthalpy ΔH(≠), entropy ΔS(≠), and energy E(a) of activation, which indicate that the distribution of OH(-) between aqueous and interface pseudophases increases ΔS(≠) but makes no contribution to E(a) and ΔH(≠). The influence of the overall concentration of AOT in the system on the rate constant has been examined and found to be negligible. It contradicts with what was reported by García-Río et al. (1) but confirms that the first-order reaction of the AOT-hydrolysis takes place on the surfactant interface. The study of the influence of AOT-hydrolysis on the kinetics of the alkaline fading of crystal violet or phenolphthalein in the water/AOT/isooctane microemulsions suggests that corrections for the AOT-hydrolysis in these reactions are required. PMID:22168828

  10. Variability of aerosol properties during the 2007-2010 spring seasons over central Europe

    NASA Astrophysics Data System (ADS)

    Pietruczuk, Aleksander; Chaikovsky, Anatoli

    2012-10-01

    Aerosol optical properties have been studied for spring seasons when increased values of PM10 are registered. Measurements of aerosol optical properties were taken by collocated lidar and sun-photometers at Belsk, Poland, and Minsk, Belarus. A significant increase of registered aerosol optical thickness (AOT) was found during episodes with elevated PM10 concentrations. An increase of AOT at 1020 nm amounted to 50% in the case of Minsk and 18% in the case of Belsk, while an increase of AOT at 400 nm was 66% and 33%, respectively. We noted an increase of Ångström exponent by 6% at both stations and no significant increase of single scattering albedo. The LIDAR measurements together with NAAPS model results and backtrajectory analysis suggest that both the biomass burning products and the Saharan dust are responsible for increased PM10 concentrations and large AOT values during spring time. The smoke aerosol is transported over Central Europe mainly in the boundary layer, increasing both PM10 concentration and AOT. The dust aerosol transported in the free troposphere slightly affects the AOT values only. Statistically significant correlation between PM10 concentration and AOT was found during reporting period.

  11. Validation of aerosol estimation in atmospheric correction algorithm ATCOR

    NASA Astrophysics Data System (ADS)

    Pflug, B.; Main-Knorn, M.; Makarau, A.; Richter, R.

    2015-04-01

    Atmospheric correction of satellite images is necessary for many applications of remote sensing, i.e. computation of vegetation indices and biomass estimation. The first step in atmospheric correction is estimation of the actual aerosol properties. Due to the spatial and temporal variability of aerosol amount and type, this step becomes crucial for an accurate correction of satellite data. Consequently, the validation of aerosol estimation contributes to the validation of atmospheric correction algorithms. In this study we present the validation of aerosol estimation using own sun photometer measurements in Central Europe and measurements of AERONET-stations at different locations in the world. Our ground-based sun photometer measurements of vertical column aerosoloptical thickness (AOT) spectra are performed synchronously to overpasses of the satellites RapidEye, Landsat 5, Landsat 7 and Landsat 8. Selected AERONET data are collocated to Landsat 8 overflights. The validation of the aerosol retrieval is conducted by a direct comparison of ground-measured AOT with satellite derived AOT using the ATCOR tool for the selected satellite images. The mean uncertainty found in our experiments is AOT550nm ~ 0.03±0.02 for cloudless conditions with cloud+haze fraction below 1%. This AOT uncertainty approximately corresponds to an uncertainty in surface albedo of ρ ~ 0.003. Inclusion of cloudy and hazy satellite images into the analysis results in mean AOT550nm ~ 0.04±0.03 for both RapidEye and Landsat imagery. About 1/3 of samples perform with the AOT uncertainty better than 0.02 and about 2/3 perform with AOT uncertainty better than 0.05.

  12. Unfolding and inactivation of cutinases by AOT and guanidine hydrochloride.

    PubMed

    Ternström, Tomas; Svendsen, Allan; Akke, Mikael; Adlercreutz, Patrick

    2005-04-15

    We present a comparative analysis of the unfolding and inactivation of three cutinases in the presence of guanidine hydrochloride (GdnHCl) and bis(2-ethylhexyl) sodium sulfosuccinate (AOT). Previous investigations have focused on the cutinase from Fusarium solani pisi (FsC). In addition to FsC, the present study includes the cutinase from Humicola insolens (HiC) and a mutant variant of HiC (muHiC) with increased activity and decreased surfactant sensitivity. Equilibrium and time-resolved denaturation by AOT were studied in aqueous solution and reverse micelles, and were compared with GdnHCl denaturation. The far-UV CD and fluorescence denaturation profiles obtained in the aqueous solutions of the two denaturants coincide for all three cutinases, indicating that unfolding is a co-operative two-state process under these conditions. In reverse micelles, the cutinases unfold with mono-exponential rates, again indicating a two-state process. The free energy of denaturation in water was calculated by linear extrapolation of equilibrium data, yielding very similar values for the three cutinases with averages of -11.6 kcal mol(-1) and -2.6 kcal mol(-1) for GdnHCl and AOT, respectively. Hence, the AOT denatured state (D(AOT)) is less destabilised than the GdnHCl denatured state (D(GdnHCl)), relative to the native state in water. Far-UV CD spectroscopy revealed that D(AOT) retains some secondary structure, while D(GdnHCl) is essentially unstructured. Similarly, fluorescence data suggest that D(AOT) is more compact than D(GdnHCl). Activity measurements reveal that both D(AOT) and D(GdnHCl) are practically inactive (catalytic activity <1% of that of the native enzyme). The fluorescence spectrum of D(AOT) in reverse micelles did not differ significantly from that observed in aqueous AOT. NMR studies of D(AOT) in reverse micelles indicated that the structure is characteristic of a molten globule, consistent with the CD and fluorescence data. PMID:15752695

  13. Aerosol climatology using a tunable spectral variability cloud screening of AERONET data

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.; Gobbi, Gian Paolo; Koren, Ilan

    2005-01-01

    Can cloud screening of an aerosol data set, affect the aerosol optical thickness (AOT) climatology? Aerosols, humidity and clouds are correlated. Therefore, rigorous cloud screening can systematically bias towards less cloudy conditions, underestimating the average AOT. Here, using AERONET data we show that systematic rejection of variable atmospheric optical conditions can generate such bias in the average AOT. Therefore we recommend (1) to introduce more powerful spectral variability cloud screening and (2) to change the philosophy behind present aerosol climatologies: Instead of systematically rejecting all cloud contaminations, we suggest to intentionally allow the presence of cloud contamination, estimate the statistical impact of the contamination and correct for it. The analysis, applied to 10 AERONET stations with approx. 4 years of data, shows almost no change for Rome (Italy), but up to a change in AOT of 0.12 in Beijing (PRC). Similar technique may be explored for satellite analysis, e.g. MODIS.

  14. MASTER: PSN in PGC135878 and OTs

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Shumkov, V.; Lipunov, V.; Buckley, D.; Lopez, R. Rebolo; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Kornilov, V.; Gorbunov, I.; Gress, O.; Ricart, M. Serra; Israelian, G.; Potter, S.; Kniazev, A.

    2016-06-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 18h 02m 41.87s +09d 03m 12.9s on 2016-06-05.16160 UT. The OT unfiltered magnitude is (limit 19.1m).The OT is seen in 10 images.

  15. MASTER: 5.2mag amplitude OT

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Lipunov, V.; Buckley, D.; Potter, S.; Kniazev, A.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kornilov, V.; Kuznetsov, A.; Vladimirov, V.; Gress, O.; Vlasenko, D.; Gorbunov, I.; Kuvshinov, D.; Shumkov, V.

    2016-03-01

    MASTER OT J203533.66-260924.0 discovery - possible dwarf nova outburst, Ampl > 5.2mag MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 20h 35m 33.66s -26d 09m 24.0s on 2016-03-12.11795 UT. The OT unfiltered magnitude is 16.8m (the limit is 19.0m).

  16. Graphical aerosol classification method using aerosol relative optical depth

    NASA Astrophysics Data System (ADS)

    Chen, Qi-Xiang; Yuan, Yuan; Shuai, Yong; Tan, He-Ping

    2016-06-01

    A simple graphical method is presented to classify aerosol types based on a combination of aerosol optical thickness (AOT) and aerosol relative optical thickness (AROT). Six aerosol types, including maritime (MA), desert dust (DD), continental (CO), sub-continental (SC), urban industry (UI) and biomass burning (BB), are discriminated in a two dimensional space of AOT440 and AROT1020/440. Numerical calculations are performed using MIE theory based on a multi log-normal particle size distribution, and the AROT ranges for each aerosol type are determined. More than 5 years of daily observations from 8 representative aerosol sites are applied to the method to confirm spatial applicability. Finally, 3 individual cases are analyzed according to their specific aerosol status. The outcomes indicate that the new graphical method coordinates well with regional characteristics and is also able to distinguish aerosol variations in individual situations. This technique demonstrates a novel way to estimate different aerosol types and provide information on radiative forcing calculations and satellite data corrections.

  17. Crystallization of confined water pools with radii greater than 1 nm in AOT reverse micelles.

    PubMed

    Suzuki, Akira; Yui, Hiroharu

    2014-07-01

    Freezing of water pools inside aerosol sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles has been investigated. Previous freezing experiments suffer from collision and fusion of AOT micelles and resultant loss of water from the water pool by shedding out during the cooling process. These phenomena have restricted the formation of ice to only when the radius of the water pool (Rw) is below 1 nm, and only amorphous ice has been observed. To overcome the size limitation, a combination of rapid cooling and a custom-made cell allowing thin sample loading is applied for instantaneous and homogeneous freezing. The freezing process is monitored with attenuated total reflection infrared spectroscopy (ATR-IR) measurements. A cooling rate of ca. -100 K/min and a sample thickness of ca. 50 μm overcomes the limitations mentioned above and allows the crystallization of water pools with larger radii (Rw > 1 nm). The corresponding ATR-IR spectra of the frozen water pools with Rw < 2.0 nm show similar features to the spectrum of metastable cubic ice (Ic). Further increase of the radius of the water pool (Rw > 2.0 nm), unfortunately, drastically decreased the integrated area of the ν(OH) band observed just after freezing, indicating the breakup of the micellar structure and shedding out of the water pool. In addition, it was revealed that Ic ice can also be formed in flexible organic self-assembled AOT reverse micelles for at least Rw ≤ ca. 2 nm, as well as in inorganic and solid materials with a pore radius of ca. 2 nm. The dependence of the phase transition temperature on the curvature of the reverse micelles is discussed from the viewpoint of the Gibbs-Thomson effect. PMID:24885023

  18. An AeroCom Initial Assessment - Optical Properties in Aerosol Component Modules of Global Models

    SciTech Connect

    Kinne, Stefan; Schulz, M.; Textor, C.; Guibert, S.; Balkanski, Y.; Bauer, S.; Berntsen, T.; Berglen, T.; Boucher, Olivier; Chin, M.; Collins, W.; Dentener, F.; Diehl, T.; Easter, Richard C.; Feichter, H.; Fillmore, D.; Ghan, Steven J.; Ginoux, P.; Gong, S.; Grini, A.; Hendricks, J.; Herzog, M.; Horrowitz, L.; Isaksen, I.; Iversen, T.; Kirkevag, A.; Kloster, S.; Koch, D.; Kristjansson, J. E.; Krol, M.; Lauer, A.; Lamarque, J. F.; Lesins, G.; Liu, Xiaohong; Lohmann, U.; Montanaro, V.; Myhre, G.; Penner, Joyce E.; Pitari, G.; Reddy, S.; Seland, O.; Stier, P.; Takemura, T.; Tie, X.

    2006-05-29

    The AeroCom exercise diagnoses multi-component aerosol modules in global modeling. In an initial assessment global fields for mass and for mid-visible aerosol optical thickness (aot) were compared among aerosol component modules of 21 different global models. There is general agreement among models for the annual global mean of component combined aot. At 0.12 to 0.14, simulated aot values are at the lower end of global averages suggested by remote sensing from ground (AERONET ca 0.14) and space (MODIS-MISR composite ca 0.16). More detailed comparisons, however, reveal that larger differences in regional distribution and significant differences in compositional mixture have remained. Of particular concern is the large model diversity for contributions by dust and carbon, because it leads to significant uncertainty in aerosol absorption (aab). Since not only aot but also aab influence the aerosol impact on the radiative energy-balance, aerosol (direct) forcing uncertainty in modeling is larger than differences in aot might suggest. New diagnostic approaches are proposed to trace model differences in terms of aerosol processing and transport: These include the prescription of common input (e.g. amount, size and injection of aerosol component emissions) and the use of observational capabilities from ground (e.g. measurements networks) and space (e.g. correlations between retrieved aerosol and cloud properties).

  19. Beijing Olympics as an aerosol field experiment

    NASA Astrophysics Data System (ADS)

    Cermak, J.; Knutti, R.

    2009-05-01

    During the 2008 Olympic Summer Games, emission reductions were enforced in Beijing to improve air quality. Here we explore their effect on the regional aerosol load. We compare satellite-retrieved aerosol optical thickness (AOT) of that period with previous years, both in absolute terms and in a neural network approach taking into account the meteorological conditions. A statistically significant reduction of aerosol load is found in Beijing that decreases in magnitude and significance with increasing region size. Locally, the aerosol load (log(AOT)) was about 0.4 to 0.75 standard deviations below the levels expected for the prevailing meteorological situation. The small size of this effect relative to meteorological variability highlights the importance of regional aerosol transport.

  20. Two novel splice variants of SOX2OT, SOX2OT-S1, and SOX2OT-S2 are coupregulated with SOX2 and OCT4 in esophageal squamous cell carcinoma.

    PubMed

    Shahryari, Alireza; Rafiee, Mahmoud Reza; Fouani, Youssef; Oliae, Nasrin Alipour; Samaei, Nader Mansour; Shafiee, Mohammad; Semnani, Shahryar; Vasei, Mohammad; Mowla, Seyed Javad

    2014-01-01

    Long noncoding RNAs (lncRNAs) have emerged as new regulators of stem cell pluripotency and tumorigenesis. The SOX2 gene, a master regulator of pluripotency, is embedded within the third intron of a lncRNA known as SOX2 overlapping transcript (SOX2OT). SOX2OT has been suspected to participate in regulation of SOX2 expression and/or other related processes; nevertheless, its potential involvement in tumor initiation and/or progression is unclear. Here, we have evaluated a possible correlation between expression patterns of SOX2OT and those of master regulators of pluripotency, SOX2 and OCT4, in esophageal squamous cell carcinoma (ESCC) tissue samples. We have also examined its potential function in the human embryonic carcinoma stem cell line, NTERA2 (NT2), which highly expresses SOX2OT, SOX2, and OCT4. Our data revealed a significant coupregulation of SOX2OT along with SOX2 and OCT4 in tumor samples, compared to the non-tumor tissues obtained from the margin of same tumors. We also identified two novel splice variants of SOX2OT (SOX2OT-S1 and SOX2OT-S2) which coupregulated with SOX2 and OCT4 in ESCCs. Suppressing SOX2OT variants caused a profound alteration in cell cycle distribution, including a 5.9 and 6.9 time increase in sub-G1 phase of cell cycle for SOX2OT-S1 and SOX2OT-S2, respectively. The expression of all variants was significantly diminished, upon the induction of neural differentiation in NT2 cells, suggesting their potential functional links to the undifferentiated state of the cells. Our data suggest a part for SOX2OT spliced variants in tumor initiation and/or progression as well as regulating pluripotent state of stem cells. PMID:24105929

  1. Phase behavior of AOT microemulsions in compressible liquids. [AOT = bis(2-ethylhexyl) sodium sulfosuccinate

    SciTech Connect

    McFann, G.J.; Johnston, K.P. )

    1991-06-13

    The phase behavior of bis(2-ethylhexyl) sodium sulfosuccinate (AOT)-alkane-brine systems is described over a wide range of pressure, temperature, and salinity for alkanes from ethane to dodecane. The partitioning of AOT between the oil, middle, and brine phases is reported for propane in order to determine the natural curvature. This is important for understanding separation processes with water-in-oil microemulsions. For the lighter, more compressible alkanes, the pressure effect on the hydrophilicity of the surfactant is much larger and in the opposite direction as for the heavier, less compressible ones. In propane at constant temperature and salinity, water-in-oil (w/o) microemulsions have been converted to middle phase microemulsions and then to oil-in-water (o/w) microemulsions by decreasing the pressure. These phase inversions are described in terms of the immiscibilities in the binary systems, and the molecular interactions at the surfactant interface. Although temperature and salinity are used commonly to manipulate interactions primarily on the water side of the interface, these results show it is possible to control interactions on the oil side by adjusting the pressure. The well-established trends in the phase behavior and size of microemulsion drops for dodecane through hexane are not observed for the lighter alkanes. For butane through ethane, a new unusual behavior is identified and attributed to a significant decrease in the strength of the attractive interactions between the surfactant tails and the alkane.

  2. Aerosol Microtops II sunphotometer observations over Ukraine

    NASA Astrophysics Data System (ADS)

    Bovchaliuk, V.; Bovchaliuk, A.; Milinevsky, G.; Danylevsky, V.; Sosonkin, M.; Goloub, Ph.

    2013-08-01

    Atmospheric aerosols and their impact on climate study are based on measurements by networks of ground-based instruments, satellite sensors, and measurements on portable sunphotometers. This paper presents the preliminary aerosol characteristics obtained during 2009-2012 using portable multi-wavelength Microtops II sunphotometer. Measurements were collected at different Ukraine sites in Kyiv, Odesa, Lugansk, Rivne, Chornobyl regions. The main aerosol characteristics, namely aerosol optical thickness (AOT) and Angstroem exponent, have been retrieved and analyzed. Aerosol data processing, filtering and calibration techniques are discussed in the paper.

  3. Saharan dust as a causal factor of hemispheric asymmetry in aerosols and cloud cover over the tropical Atlantic Ocean

    SciTech Connect

    Kishcha, Pavel; Da Sliva, Arlindo; Starobinets, Boris; Long, Charles N.; Kalashnikova, Olga; Alpert, Pinhas

    2015-07-09

    Meridional distribution of aerosol optical thickness (AOT) over the tropical Atlantic Ocean (30°N – 30°S) was analyzed to assess seasonal variations of meridional AOT asymmetry. Ten-year MERRA Aerosol Reanalysis (MERRAero) data (July 2002 – June 2012) confirms that the Sahara desert emits a significant amount of dust into the atmosphere over the Atlantic Ocean. Only over the Atlantic Ocean did MERRAero show that desert dust dominates other aerosol species and is responsible for meridional aerosol asymmetry between the tropical North and South Atlantic. Over the 10-year period under consideration, both MISR measurements and MERRAero data showed a pronounced meridional AOT asymmetry. The meridional AOT asymmetry, characterized by the hemispheric ratio (RAOT) of AOT averaged separately over the North and over the South Atlantic, was about 1.7. Seasonally, meridional AOT asymmetry over the Atlantic was the most pronounced between March and July, when dust presence is maximal (RAOT ranged from 2 to 2.4). There was no noticeable meridional aerosol asymmetry in total AOT from September to October. During this period the contribution of carbonaceous aerosols to total AOT in the South Atlantic was comparable to the contribution of dust aerosols to total AOT in the North Atlantic. During the same 10-year period, MODIS cloud fraction (CF) data showed that there was no noticeable asymmetry in meridional CF distribution in different seasons (the hemispheric ratio of CF ranged from 1.0 to 1.2). MODIS CF data illustrated significant cloud cover (CF of 0.7 – 0.9) with limited precipitation ability along the Saharan Air Layer.

  4. Master-Iac Master-Saao OTs

    NASA Astrophysics Data System (ADS)

    Pogrosheva, T.; Vladimirov, V.; Lipunov, V.; Lopez, R. Rebolo; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Balanutsa, P.; Kornilov, V.; Gorbunov, I.; Gress, O.; Shumkov, V.; Ricart, M. Serra; Israelian, G.; Potter, S.; Kniazev, A.

    2016-06-01

    MASTER-IAC auto-detection system( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 20h 58m 16.98s +23d 58m 12.6s on 2016-06-09.03890 UT. The OT unfiltered magnitude is 17.5m (limit 19.4m).

  5. MASTER-SAAO: bright outbursting OT

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Lipunov, V.; Buckley, D.; Kornilov, V.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Gress, O.; Kuznetsov, A.; Kuvshinov, D.; Vladimirov, V.; Gorbunov, I.; Vlasenko, D.; Popova, E.; Potter, S.; Kniazev, A.; Shurpakov, S.

    2016-04-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 21h 29m 20.71s -62d 08m 52.2s on 2016-04-27.985 UT. The OT unfiltered magnitude is 17.3m (the limit is 19.3m).

  6. MASTER-Net: PSN and 3 OTs

    NASA Astrophysics Data System (ADS)

    Gorbovskoy, E.; Balanutsa, P.; Lipunov, V.; Lopez, R. Rebolo; Ricart, M. Serra; Buckley, D.; Israelian, G.; Tiurina, N.; Kornilov, V.; Kuznetsov, A.; Gress, O.; Shumkov, V.; Gorbunov, I.; Vlasenko, D.; Vladimirov, V.; Popova, E.; Potter, S.; Kotze, M.; Tlatov, A.; Senik, V.; Dormidontov, D.; Parkhomenko, A.

    2016-02-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 16h 33m 55.46s +86d 08m 30.4s on 2016-02-13.88456 UT. The OT unfiltered magnitude is (limit 18.6m).

  7. Impact of aerosol on air temperature in Kuwait

    NASA Astrophysics Data System (ADS)

    Sabbah, I.

    2010-08-01

    This work uses MODIS aerosol optical thickness (AOT) data observed over Kuwait during the 7-year interval 2000-2007. The values of AOT and the Ångström wavelength exponent ( α) show a clear annual cycle. These data are categorized into two catalogues in terms of the values of the AOT of the 870 nm channel ( τ870). One catalogue (71 days) includes days with high values of AOT ( τ870 ≥ 0.75). The most probable "modal" value of α for these days is 0.52. The other catalogue (1162 days) consists of the background days with a modal value ~ 1.1 for the exponent α. This analysis is extended to include water vapor content (WVC), surface wind speed (V), visibility (Vis) and the diurnal temperature range (DTR). Chree's method of superposed-epoch analysis is applied to these parameters in order to compare the variation in the daily averages during days with high AOT values with respect to background days. The high values of AOT during the 71 days are positively correlated with aerosol size, near-surface winds and poor visibility. This concludes that the aerosol particles during these days were mostly dust. The mean daily value of the DTR (Δ T) and visibility reduced significantly during these days. This reduction on DTR is a direct result of increasing the atmospheric opacity due to the presence of dust.

  8. A new method of measuring aerosol optical properties from digital twilight photographs

    NASA Astrophysics Data System (ADS)

    Saito, M.; Iwabuchi, H.

    2015-01-01

    An optimal-estimation algorithm for inferring aerosol optical properties from digital twilight photographs is proposed. The sensitivity of atmospheric components and surface characteristics to brightness and color of twilight sky is investigated, and the results suggest that tropospheric and stratospheric aerosol optical thickness (AOT) are sensitive to condition of the twilight sky. The coarse-fine particle volume ratio is moderately sensitive to the sky condition near the horizon under a clean-atmosphere condition. A radiative transfer model that takes into account a spherical-shell atmosphere, refraction, and multiple scattering is used as a forward model. Error analysis shows that the tropospheric and stratospheric AOT can be retrieved without significant bias. Comparisons with results from other ground-based instruments exhibit reasonable agreement on AOT. A case study suggests that the AOT retrieval method can be applied to atmospheric conditions with varying aerosol vertical profiles and vertically inhomogeneous species in the troposphere.

  9. A new method of measuring aerosol optical properties from digital twilight photographs

    NASA Astrophysics Data System (ADS)

    Saito, M.; Iwabuchi, H.

    2015-10-01

    An optimal-estimation algorithm for inferring aerosol optical properties from digital twilight photographs is proposed. The sensitivity of atmospheric components and surface characteristics to brightness and color of twilight sky is investigated, and the results suggest that tropospheric and stratospheric aerosol optical thickness (AOT) are sensitive to condition of the twilight sky. The coarse-fine particle volume ratio is moderately sensitive to the sky condition near the horizon under a clean-atmosphere condition. A radiative transfer model that takes into account a spherical-shell atmosphere, refraction, and multiple scattering is used as a forward model. Error analysis shows that the tropospheric and stratospheric AOT can be retrieved without significant bias. Comparisons with results from other ground-based instruments exhibit reasonable agreement on AOT. A case study suggests that the AOT retrieval method can be applied to atmospheric conditions with varying aerosol vertical profiles and vertically inhomogeneous species in the troposphere.

  10. Electron spin echo modulation study of AOT reverse micelles

    SciTech Connect

    Baglioni, P. ); Nakamura, Hiroshi ); Kevan, L. )

    1991-05-02

    Electron spin echo deuterium modulation studies have been carried out for x-doxylstearic acid spin probes in frozen reversed micellar solutions of sodium bis(2-ethyl-1-hexyl) sulfosuccinate (AOT)/isooctane as a function of the water pool size with deuterium located in the isooctane or in the water. The results determine the probe location and conformation in the reverse micelle and the amount of water and isooctane penetration into the AOT interface. Modulation effects due to the interaction of the unpaired electron with deuterated isooctane or deuterated water show that the probes are in an extended conformation and are located at the interface of the reverse micelle. The results obtained are in good agreement with the current view of the structure of AOT reversed micelles in liquids and demonstrate at a molecular level that the micellar structure is retained upon fast freezing.

  11. Formation of nanosized titania particles in AOT microemulsions

    SciTech Connect

    Moran, P.D.; Bowmaker, G.A.; Cooney, R.P.

    1995-09-01

    Titania nanoparticles have been produced by the controlled hydrolysis of tetraisopropyltitanate (TPT) in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. Particle formation and aggregation were investigated by static and dynamic light scattering and the chemical species by FT-IR and FT-Raman spectroscopy. The kinetics of particle formation and aggregation were controlled by varying [H{sub 2}O]/[AOT] (w{sub o}), [H{sub 2}O]/[Ti(IV)] and [AOT]/[Ti(IV)]. Nanoparticles, with diameters < 10 nm, could be produced at relatively high Ti(IV) concentrations (up to 0.05 M). These nanoparticles aggregated into sols, with colloid sizes of 20 to 200 nm, eventually forming gelatinous precipitates. Different titania phases were produced, depending on the size of the micellar water pool; small pools (w{sub 0} < 6) yielded amorphous particles, while large pools (w{sub 0} > 10) produced anatase.

  12. Evaluation of allowed outage times (AOTs) from a risk and reliability standpoint

    SciTech Connect

    Vesely, W.E. )

    1989-08-01

    This report describes the basic risks which are associated with allowed outage times (AOTs), defines strategies for selecting the risks to be quantified, and describes how the risks can be quantified. The report furthermore describes criteria considerations in determining the acceptability of calculated AOT risks, and discusses the merits of relative risk criteria versus absolute risk criteria. The detailed evaluations which are involved in calculating AOT risks, including uncertainty considerations are also discussed. The report also describes the proper ways that risks from multiple AOTs should be considered so that risks are properly accumulated from proposed multiple AOT changes, but are not double-counted. Generally, average AOT risks which include the frequency of occurrence of the AOT need to be accumulated but single downtime risks don't since they apply to individual AOTs. 8 refs., 22 tabs.

  13. Integral physicochemical properties of reverse micelles of sodium bis(2-ethylhexyl) sulfosuccinate (AOT)

    NASA Astrophysics Data System (ADS)

    Fedyaeva, O. A.; Shubenkova, E. G.; Poshelyuzhnaya, E. G.; Lutaeva, I. A.

    2016-08-01

    The effect the degree of hydration has on optical and electrophysical properties of water/AOT/ n-hexane system is studied. It is found that AOT reverse micelles form aggregates whose dimensions grow along with the degree of hydration and temperature. Aggregation enhances their electrical conductivity and shifts the UV spectrum of AOT reverse emulsions to the red region. Four states of water are found in the structure of AOT reverse micelles.

  14. A 10-year global gridded Aerosol Optical Thickness Reanalysis for climate and applied applications

    NASA Astrophysics Data System (ADS)

    Lynch, P.; Reid, J. S.; Zhang, J.; Westphal, D. L.; Campbell, J. R.; Curtis, C. A.; Hegg, D.; Hyer, E. J.; Sessions, W.; Shi, Y.; Turk, J.

    2013-12-01

    While standalone satellite and model aerosol products see wide utilization, there is a significant need of a best-available fused product on a regular grid for numerous climate and applied applications. Remote sensing and modeling technologies have now advanced to a point where aerosol data assimilation is an operational reality at numerous centers. It is inevitable that, like meteorological reanalyses, aerosol reanalyses will see heavy use in the near future. A first long term, 2003-2012 global 1x1 degree and 6-hourly aerosol optical thickness (AOT) reanalysis product has been generated. The goal of this effort is not only for climate applications, but to generate a dataset that can be used by the US Navy to understand operationally hindering aerosol events, aerosol impacts on numerical weather prediction, and application of electro-optical technologies. The reanalysis utilizes Navy Aerosol Analysis and Prediction System (NAAPS) at its core and assimilates quality controlled collection 5 Moderate Resolution Imaging Spectroradiometer (MODIS) AOD with minor corrections from Multi-angle Imaging SpectroRaditometer (MISR). A subset of this product includes Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) lidar assimilation since its launch in mid-2006. Surface aerosol sources, including dust and smoke, in the aerosol model have been regionally tuned so that fine and coarse mode AOTs best match those resolve by ground-based Aerosol Robotic Network (AERONET). The AOT difference between the model and satellite AOT is then used to adjust other aerosol processes, eg., sources, dry deposition, etc. Aerosol wet deposition is constrained with satellite-retrieved precipitation. The final AOT reanalysis is shown to exhibit good agreement with AERONET. Here we review the development of the reanalysis and consider issues particular to aerosol reanalyses that make them distinct from standard meteorological reanalyses. Considerations are also made for extending such work

  15. Electron spin resonance and electron spin echo modulation studies of the photoionization of N-Alkyl-N,N[prime],N[prime]-trimethylbenzidines in AOT reversed micelles

    SciTech Connect

    Stenland, C.; Kevan, L. )

    1993-10-07

    N-Alkyl-N,N[prime],N[prime]-trimethylbenzidines (C[sub n]TMB,n = 1, 4, 8, 12, 16) were photoionized in rapidly frozen reversed micelles composed of sodium bis(2-ethyl-1-hexyl) sulfosuccinate or aerosol dioctyl (AOT) in isooctane with 4, 9, 14, 24, 34, and 44 mole ratios of water/AOT. The relative photoyields after irradiation with 300-400-nm light were measured by electron spin resonance. The photoyield decreased as the mole ratio of water to AOT increased. This is interpreted as a more negative surface charge density at the organic-aqueous interface as increased water more completely solvates the sodium counterions. The higher negative surface charge density forms a higher barrier for the photoelectron to surmount to enter the water pool. Electron spin echo modulation spectroscopy was used to probe the local magnetic nuclear environment of the photoproduced cation radicals in these reversed micelles and indicate that the cation radicals are located near the interface. Secondary radicals due to interaction of the AOT headgroup with photoelectrons are observed and assigned. 27 refs., 8 figs.

  16. Intercomparison of aerosol extinction profiles retrieved from MAX-DOAS measurements

    NASA Astrophysics Data System (ADS)

    Frieß, U.; Klein Baltink, H.; Beirle, S.; Clémer, K.; Hendrick, F.; Henzing, B.; Irie, H.; de Leeuw, G.; Li, A.; Moerman, M. M.; van Roozendael, M.; Shaiganfar, R.; Wagner, T.; Wang, Y.; Xie, P.; Yilmaz, S.; Zieger, P.

    2016-07-01

    A first direct intercomparison of aerosol vertical profiles from Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations, performed during the Cabauw Intercomparison Campaign of Nitrogen Dioxide measuring Instruments (CINDI) in summer 2009, is presented. Five out of 14 participants of the CINDI campaign reported aerosol extinction profiles and aerosol optical thickness (AOT) as deduced from observations of differential slant column densities of the oxygen collision complex (O4) at different elevation angles. Aerosol extinction vertical profiles and AOT are compared to backscatter profiles from a ceilometer instrument and to sun photometer measurements, respectively. Furthermore, the near-surface aerosol extinction coefficient is compared to in situ measurements of a humidity-controlled nephelometer and dry aerosol absorption measurements. The participants of this intercomparison exercise use different approaches for the retrieval of aerosol information, including the retrieval of the full vertical profile using optimal estimation and a parametrised approach with a prescribed profile shape. Despite these large conceptual differences, and also differences in the wavelength of the observed O4 absorption band, good agreement in terms of the vertical structure of aerosols within the boundary layer is achieved between the aerosol extinction profiles retrieved by the different groups and the backscatter profiles observed by the ceilometer instrument. AOTs from MAX-DOAS and sun photometer show a good correlation (R>0.8), but all participants systematically underestimate the AOT. Substantial differences between the near-surface aerosol extinction from MAX-DOAS and from the humidified nephelometer remain largely unresolved.

  17. Saharan dust as a causal factor of hemispheric asymmetry in aerosols and cloud cover over the tropical Atlantic Ocean

    DOE PAGESBeta

    Kishcha, Pavel; Da Sliva, Arlindo; Starobinets, Boris; Long, Charles N.; Kalashnikova, Olga; Alpert, Pinhas

    2015-07-09

    Meridional distribution of aerosol optical thickness (AOT) over the tropical Atlantic Ocean (30°N – 30°S) was analyzed to assess seasonal variations of meridional AOT asymmetry. Ten-year MERRA Aerosol Reanalysis (MERRAero) data (July 2002 – June 2012) confirms that the Sahara desert emits a significant amount of dust into the atmosphere over the Atlantic Ocean. Only over the Atlantic Ocean did MERRAero show that desert dust dominates other aerosol species and is responsible for meridional aerosol asymmetry between the tropical North and South Atlantic. Over the 10-year period under consideration, both MISR measurements and MERRAero data showed a pronounced meridional AOTmore » asymmetry. The meridional AOT asymmetry, characterized by the hemispheric ratio (RAOT) of AOT averaged separately over the North and over the South Atlantic, was about 1.7. Seasonally, meridional AOT asymmetry over the Atlantic was the most pronounced between March and July, when dust presence is maximal (RAOT ranged from 2 to 2.4). There was no noticeable meridional aerosol asymmetry in total AOT from September to October. During this period the contribution of carbonaceous aerosols to total AOT in the South Atlantic was comparable to the contribution of dust aerosols to total AOT in the North Atlantic. During the same 10-year period, MODIS cloud fraction (CF) data showed that there was no noticeable asymmetry in meridional CF distribution in different seasons (the hemispheric ratio of CF ranged from 1.0 to 1.2). MODIS CF data illustrated significant cloud cover (CF of 0.7 – 0.9) with limited precipitation ability along the Saharan Air Layer.« less

  18. Simulation of aerosol optical thickness during IMPACT (May 2008, The Netherlands) with ECHAM5-HAM

    NASA Astrophysics Data System (ADS)

    Roelofs, G.-J.; ten Brink, H.; Kiendler-Scharr, A.; de Leeuw, G.; Mensah, A.; Minikin, A.; Otjes, R.

    2010-03-01

    In May 2008 the measurement campaign IMPACT for observation of atmospheric aerosol and cloud properties was conducted in Cabauw (The Netherlands). With a nudged version of the coupled aerosol-climate model ECHAM5-HAM we simulate aerosol and aerosol optical thickness (AOT) for the campaign period. Synoptic scale meteorology is represented realistically and simulated concentrations of aerosol sulfate and organics at the surface are generally within a factor of two from observed values. The monthly averaged AOT from the model is 0.33, about 20% larger than observed. For selected periods of the month with relatively dry and moist conditions discrepancies are approximately -30% and +15%, respectively. Discrepancies during the dry period are partly caused by inaccurate representation of boundary layer (BL) dynamics by the model affecting the simulated AOT. The model simulates too strong exchange between the BL and the free troposphere, resulting in weaker concentration gradients at the BL top than observed for aerosol and humidity, while upward mixing from the surface layers into the BL appears to be underestimated. The results indicate that beside aerosol sulfate and organics also aerosol ammonium and nitrate significantly contribute to aerosol water uptake. The relation between particle concentration and AOT is rather weak during IMPACT. The simulated day-to-day variability of AOT follows synoptic scale advection of humidity rather than particle concentration. Even for relatively dry conditions AOT appears to be strongly influenced by the diurnal cycle of RH in the lower boundary layer, further enhanced by uptake and release of nitric acid and ammonia by aerosol water.

  19. Does the Madden-Julian Oscillation Influence Aerosol Variability?

    NASA Astrophysics Data System (ADS)

    Tian, B.; Waliser, D. E.; Kahn, R. A.; Li, Q.; Yung, Y. L.; Tyranowski, T.; Geogdzhayev, I. V.; Mishchenko, M. I.; Torres, O.; Smirnov, A.

    2007-12-01

    We investigate the modulation of aerosols by the Madden-Julian Oscillation (MJO) using satellite-based global aerosol products, including aerosol index (AI) from the Total Ozone Mapping Spectrometer (TOMS) on Nimbus-7, and aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Advanced Very High Resolution Radiometer (AVHRR) on NOAA satellites. A composite analysis is performed for boreal winter, and the global pentad rainfall data from the NOAA Climate Prediction Center (CPC) Merged Analysis of Precipitation (CMAP) are used to identify MJO events. The MJO composites exhibit large variations in the TOMS AI and MODIS/AVHRR AOT over the equatorial Indian and western Pacific Oceans where MJO convection is active, as well as the tropical Africa and Atlantic Ocean where MJO convection is relatively weak but the background aerosol level is relatively high. A strong inverse linear relationship between the TOMS AI and rainfall anomalies, but a weaker, less coherent positive correlation between the MODIS/AVHRR AOT and rainfall anomalies, were found. The Aerosol Robotic Network AOT pattern at Kaashidoo (73.5°E, 4.9°N) and Nauru (167°E, 0.5°S) is more consistent with MODIS and AVHRR. These results indicate a connection between the MJO, its associated rainfall and circulation variability, and the observed aerosol variations. Several physical and non-physical factors that may contribute to the observed aerosol-rainfall relationship, such as aerosol humidification effect, wet deposition, surface wind speed, phytoplankton, different sensor sensitivities (absorbing versus non-absorbing aerosols and upper versus lower tropospheric aerosols), sampling issue, and cloud contamination, are discussed. However, a clear causal explanation for the observed patterns remains elusive. Further investigation is needed to unravel this complex aerosol-rainfall relationship.

  20. Aerosol extinction in a remote continental region of the Iberian Peninsula during summer

    NASA Astrophysics Data System (ADS)

    Elias, Thierry; Silva, Ana Maria; Belo, Nuno; Pereira, Sergio; Formenti, Paola; Helas, Günter; Wagner, Frank

    2006-07-01

    Summer in Évora (38°34'N, 7°54'W), Portugal, is described in terms of aerosol properties of extinction of the solar radiation. We create a data set composed of (1) cloud-screened half-day averaged values of aerosol optical thickness (AOT) measured at 7 wavelengths by both a CIMEL Sun/sky-photometer and a YES shadowband radiometer and (2) half day averaged values of aerosol scattering coefficient (ASC) measured at the surface level at two wavelengths by a TSI nephelometer. Spectral dependence of both AOT and ASC gives the column and the surface Ångström exponents, αC and αS, respectively. Measurements are acquired in both 2002 and 2003 summers. Back trajectories are computed. A statistical study of the data set provides thresholds in AOT and αC for a classification of the days. The classification is applied with success to the case study of the 2003 summer heat wave episode and is generalized to the whole data set. In 23% of the cases, the turbidity in Évora is very low, with AOT441 < 0.12 and AOT873 < 0.04. The air mass origin is the North Atlantic Ocean at 700 and 970 hPa. In 31% of the cases, the turbidity is high. Increase of AOT is due to forest fire emissions, originating in the Iberian Peninsula, with 0.30 < AOT441 < 1.10 and αC > 1.2, and to desert dust plumes transported from North Africa within 72 to 120 hours at 700 hPa, with 0.10 < AOT873 < 1.10 and 0.1 < αC < 1.0. The vertical profile is highly variable, and several cases of aerosol mixing in the column are identified. The duration of the aerosol episode during the 2003 summer heat wave is 16 days, which is exceptionally long.

  1. Daytime Variation of Shortwave Direct Radiative Forcing of Biomass Burning Aerosols from GOES-8 Imager.

    NASA Astrophysics Data System (ADS)

    Christopher, Sundar A.; Zhang, Jianglong

    2002-02-01

    Hourly Geostationary Operational Environmental Satellite-8 (GOES-8) imager data (1344-1944 UTC) from 20 July-31 August 1998 were used to study the daytime variation of shortwave direct radiative forcing (SWARF) of smoke aerosols over biomass burning regions in South America (4°-16°S, 51°-65°W). Vicarious calibration procedures were used to adjust the GOES visible channel reflectance values for the degradation in signal response. Using Mie theory and discrete ordinate radiative transfer (DISORT) calculations, smoke aerosol optical thickness (AOT) was estimated at 0.67 m. The GOES-retrieved AOT was then compared against ground-based AOT retrieved values. Using the retrieved GOES-8 AOT, a four-stream broadband radiative transfer model was used to compute shortwave fluxes for smoke aerosols at the top of the atmosphere (TOA). The daytime variation of smoke AOT and SWARF was examined for the study area. For selected days, the Clouds and the Earth's Radiant Energy System (CERES) TOA shortwave (SW) fluxes are compared against the model-derived SW fluxes.Results of this study show that the GOES-derived AOT is in excellent agreement with Aerosol Robotic Network (AERONET)-derived AOT values with linear correlation coefficient of 0.97. The TOA CERES-estimated SW fluxes compare well with the model-calculated SW fluxes with linear correlation coefficient of 0.94. For August 1998 the daytime diurnally averaged AOT and SWARF for the study area is 0.63 ± 0.39 and 45.8 ± 18.8 W m2, respectively. This is among the first studies to estimate the daytime diurnal variation of SWARF of smoke aerosols using satellite data.

  2. Micelle and microemulsion properties of cesium di-dodecyl-dimethylsulfosuccinate, Cs-AOT

    SciTech Connect

    Sheu, E.Y.; Nostro, P.L.; Capuzzi, G.; Baglioni, P.

    1999-09-28

    Cesium di-2-ethylsulfosuccinate (Cs-AOT) micelles in aqueous solutions and Cs-AOT/water/n-decane microemulsions were investigated, at 22 {plus{underscore}minus} 0.1 C, by small angle neutron scattering (SANS). The critical micelle concentration of Cs-AOT is {approximately}2mM, comparable to that of Na-AOT. However, their solution properties and micellar structures were found to be very different. The solubility of Na-AOT in water is approximately 1 wt %, and the micelles grow from spherical (at a concentration of about 0.1 wt %) to oblate objects with eccentricity equal to about 0.8 (at a concentration of 1 wt %), whereas Cs-AOT is largely soluble in water, over 30 wt %, and its micelles are disklike at 1 wt %. As the surfactant concentration increases, micelles may go through an L{sub 3} region, and enter the lamellar phase. Cs-AOT/water/n-decane microemulsions, with a [water]/[Cs-AOT] = 29.1, form isotropic L{sub 2} phases only at very low Cs-AOT + ater volume fractions (below 0.0165), whereas Na-AOT has a large L{sub 2} region. These differences are probably due to the degree of charge condensation near the AOT polar headgroups. A theoretical description is needed to better understand this behavior.

  3. Retrieval of spectral aerosol optical thickness over land using ocean color sensors MERIS and SeaWiFS

    NASA Astrophysics Data System (ADS)

    von Hoyningen-Huene, W.; Yoon, J.; Vountas, M.; Istomina, L. G.; Rohen, G.; Dinter, T.; Kokhanovsky, A. A.; Burrows, J. P.

    2011-02-01

    For the determination of aerosol optical thickness (AOT) Bremen AErosol Retrieval (BAER) has been developed. Method and main features on the aerosol retrieval are described together with validation and results. The retrieval separates the spectral aerosol reflectance from surface and Rayleigh path reflectance for the shortwave range of the measured spectrum of top-of-atmosphere reflectance for wavelength less than 0.670 μm. The advantage of MERIS (Medium Resolution Imaging Spectrometer on the Environmental Satellite - ENVISAT - of the European Space Agency - ESA) and SeaWiFS (Sea viewing Wide Field Sensor on OrbView-2 spacecraft) observations is the availability of several spectral channels in the blue and visible range enabling the spectral determination of AOT in 7 (or 6) channels (0.412-0.670 μm) and additionally channels in the NIR, which can be used to characterize the surface properties. A dynamical spectral surface reflectance model for different surface types is used to obtain the spectral surface reflectance for this separation. The normalized differential vegetation index (NDVI), taken from the satellite observations, is the model input. Further surface bi-directional reflectance distribution function (BRDF) is considered by the Raman-Pinty-Verstraete (RPV) model. Spectral AOT is obtained from aerosol reflectance using look-up-tables, obtained from radiative transfer calculations with given aerosol phase functions and single scattering albedos either from aerosol models, given by model package "optical properties of aerosol components" (OPAC) or from experimental campaigns. Validations of the obtained AOT retrieval results with data of Aerosol Robotic Network (AERONET) over Europe gave a preference for experimental phase functions derived from almucantar measurements. Finally long-term observations of SeaWiFS have been investigated for 11 year trends in AOT. Western European regions have negative trends with decreasing AOT with time. For the

  4. Development towards a global operational aerosol consensus: basic climatological characteristics of the International Cooperative for Aerosol Prediction Multi-Model Ensemble (ICAP-MME)

    NASA Astrophysics Data System (ADS)

    Sessions, W. R.; Reid, J. S.; Benedetti, A.; Colarco, P. R.; da Silva, A.; Lu, S.; Sekiyama, T.; Tanaka, T. Y.; Baldasano, J. M.; Basart, S.; Brooks, M. E.; Eck, T. F.; Iredell, M.; Hansen, J. A.; Jorba, O. C.; Juang, H.-M. H.; Lynch, P.; Morcrette, J.-J.; Moorthi, S.; Mulcahy, J.; Pradhan, Y.; Razinger, M.; Sampson, C. B.; Wang, J.; Westphal, D. L.

    2015-01-01

    Here we present the first steps in developing a global multi-model aerosol forecasting ensemble intended for eventual operational and basic research use. Drawing from members of the International Cooperative for Aerosol Prediction (ICAP) latest generation of quasi-operational aerosol models, 5-day aerosol optical thickness (AOT) forecasts are analyzed for December 2011 through November 2012 from four institutions: European Centre for Medium-Range Weather Forecasts (ECMWF), Japan Meteorological Agency (JMA), NASA Goddard Space Flight Center (GSFC), and Naval Research Lab/Fleet Numerical Meteorology and Oceanography Center (NRL/FNMOC). For dust, we also include the National Oceanic and Atmospheric Administration-National Geospatial Advisory Committee (NOAA NGAC) product in our analysis. The Barcelona Supercomputing Centre and UK Met Office dust products have also recently become members of ICAP, but have insufficient data to be included in this analysis period. A simple consensus ensemble of member and mean AOT fields for modal species (e.g., fine and coarse mode, and a separate dust ensemble) is used to create the ICAP Multi-Model Ensemble (ICAP-MME). The ICAP-MME is run daily at 00:00 UTC for 6-hourly forecasts out to 120 h. Basing metrics on comparisons to 21 regionally representative Aerosol Robotic Network (AERONET) sites, all models generally captured the basic aerosol features of the globe. However, there is an overall AOT low bias among models, particularly for high AOT events. Biomass burning regions have the most diversity in seasonal average AOT. The Southern Ocean, though low in AOT, nevertheless also has high diversity. With regard to root mean square error (RMSE), as expected the ICAP-MME placed first over all models worldwide, and was typically first or second in ranking against all models at individual sites. These results are encouraging; furthermore, as more global operational aerosol models come online, we expect their inclusion in a robust

  5. Aerosol Typing by 3-Wavelength Elastic Lidar Signals Over the Central Mediterranean

    NASA Astrophysics Data System (ADS)

    Perrone, Maria Rita; Burlizzi, Pasquale

    2016-06-01

    Elastic lidar signals at 355, 532, and 1064 nm combined with aerosol optical thicknesses (AOTs) from sunphotometer measurements collocated in space and time have been used to retrieve columnar lidar ratio (LR) values at the lidar wavelengths by a constrained iterative inversion procedure. Then, the relationships of LRs with AOTs, Ångström exponents, fine mode fractions (η), and fine mode radii (Rf) have been investigated for the aerosol typing. η and Rf values have been retrieved from a graphical framework. It is shown that the implemented methodology has allowed identifying three main aerosol types over the Central Mediterranean which are designed as urban/industrial, marine-polluted, and mixed-dust. Results on the relationships of LRs with AOTs, Å, η, and Rf for each aerosol type represent main paper results.

  6. Separating Real and Apparent Effects of Cloud, Humidity, and Dynamics on Aerosol Optical Thickness near Cloud Edges

    NASA Technical Reports Server (NTRS)

    Jeong, Myeong-Jae; Li, Zhanqing

    2010-01-01

    Aerosol optical thickness (AOT) is one of aerosol parameters that can be measured on a routine basis with reasonable accuracy from Sun-photometric observations at the surface. However, AOT-derived near clouds is fraught with various real effects and artifacts, posing a big challenge for studying aerosol and cloud interactions. Recently, several studies have reported correlations between AOT and cloud cover, pointing to potential cloud contamination and the aerosol humidification effect; however, not many quantitative assessments have been made. In this study, various potential causes of apparent correlations are investigated in order to separate the real effects from the artifacts, using well-maintained observations from the Aerosol Robotic Network, Total Sky Imager, airborne nephelometer, etc., over the Southern Great Plains site operated by the U.S. Department of Energy's Atmospheric Radiation Measurement Program. It was found that aerosol humidification effects can explain about one fourth of the correlation between the cloud cover and AOT. New particle genesis, cloud-processed particles, atmospheric dynamics, and aerosol indirect effects are likely to be contributing to as much as the remaining three fourth of the relationship between cloud cover and AOT.

  7. Extension, validation, and analysis of the multi-decadal GACP/AVHRR aerosol optical thickness record

    NASA Astrophysics Data System (ADS)

    Mishchenko, M. I.; Geogdzhayev, I. V.

    2015-12-01

    The main product of the Global Aerosol Climatology Project (GACP) is a continuous record of the aerosol optical thickness (AOT) over the oceans based on channel-1 and -2 radiances from successively flown AVHRR instruments. We extend the previous GACP dataset by four years though the end of 2009 using NOAA-17 and -18 AVHRR data recalibrated against MODIS radiances according to Heidinger et al. (2010), thereby making the GACP record almost three decades long. The temporal overlap of the new NOAA-17 and the previous NOAA-16 record reveals an excellent agreement of the corresponding global monthly mean AOT values, thereby confirming the robustness of the vicarious radiance calibration used in the original GACP product. A comprehensive set of monthly mean AOT data from coastal and insular AERONET stations was used to validate GACP retrievals for the period 1995-2009. To put the GACP performance in broader perspective, we also compared AERONET and MODIS Aqua level-2 data for 2003-2009 using the same methodology. Monthly mean AOTs from the two over-the-ocean satellite datasets are well correlated with the ground-based values, the correlation coefficients being 0.81-0.85 for GACP and 0.74-0.79 for MODIS. Regression analyses demonstrated that the GACP mean AOTs are approximately 17%-27% lower than the AERONET values on average, while the MODIS mean AOTs are 5%-25% higher. The previously identified negative trend in the global GACP AOT which started in the late 1980s and continued into the early 2000s was confirmed. Its magnitude and duration indicate that it was caused by changes in tropospheric aerosols. The latest multi-satellite segment of the GACP record shows that this trend tapered off, with no noticeable AOT change after 2002. This result is consistent with the MODIS and MISR AOT records as well as with the recent gradual reversal from brightening to dimming revealed by surface flux measurements in many aerosol producing regions. Thus the robustness of the GACP

  8. Evaluation of simulated aerosol properties with the aerosol-climate model ECHAM5-HAM using observations from the IMPACT field campaign

    NASA Astrophysics Data System (ADS)

    Roelofs, G.-J.; ten Brink, H.; Kiendler-Scharr, A.; de Leeuw, G.; Mensah, A.; Minikin, A.; Otjes, R.

    2010-08-01

    In May 2008, the measurement campaign IMPACT for observation of atmospheric aerosol and cloud properties was conducted in Cabauw, The Netherlands. With a nudged version of the coupled aerosol-climate model ECHAM5-HAM we simulate the size distribution and chemical composition of the aerosol and the associated aerosol optical thickness (AOT) for the campaign period. Synoptic scale meteorology is represented realistically through nudging of the vorticity, the divergence, the temperature and the surface pressure. Simulated concentrations of aerosol sulfate and organics at the surface are generally within a factor of two from observed values. The monthly averaged AOT from the model is 0.33, about 20% larger than observed. For selected periods of the month with relatively dry and moist conditions discrepancies are approximately -30% and +15%, respectively. Discrepancies during the dry period are partly caused by inaccurate representation of boundary layer (BL) dynamics by the model affecting the simulated AOT. The model simulates too strong exchange between the BL and the free troposphere, resulting in weaker concentration gradients at the BL top than observed for aerosol and humidity, while upward mixing from the surface layers into the BL appears to be underestimated. The results indicate that beside aerosol sulfate and organics also aerosol ammonium and nitrate significantly contribute to aerosol water uptake. The simulated day-to-day variability of AOT follows synoptic scale advection of humidity rather than particle concentration. Even for relatively dry conditions AOT appears to be strongly influenced by the diurnal cycle of RH in the lower boundary layer, further enhanced by uptake and release of nitric acid and ammonia by aerosol water.

  9. Online Simulations of Global Aerosol Distributions in the NASA GEOS-4 Model and Comparisons to Satellite and Ground-Based Aerosol Optical Depth

    NASA Technical Reports Server (NTRS)

    Colarco, Peter; daSilva, Arlindo; Chin, Mian; Diehl, Thomas

    2010-01-01

    We have implemented a module for tropospheric aerosols (GO CART) online in the NASA Goddard Earth Observing System version 4 model and simulated global aerosol distributions for the period 2000-2006. The new online system offers several advantages over the previous offline version, providing a platform for aerosol data assimilation, aerosol-chemistry-climate interaction studies, and short-range chemical weather forecasting and climate prediction. We introduce as well a methodology for sampling model output consistently with satellite aerosol optical thickness (AOT) retrievals to facilitate model-satellite comparison. Our results are similar to the offline GOCART model and to the models participating in the AeroCom intercomparison. The simulated AOT has similar seasonal and regional variability and magnitude to Aerosol Robotic Network (AERONET), Moderate Resolution Imaging Spectroradiometer, and Multiangle Imaging Spectroradiometer observations. The model AOT and Angstrom parameter are consistently low relative to AERONET in biomass-burning-dominated regions, where emissions appear to be underestimated, consistent with the results of the offline GOCART model. In contrast, the model AOT is biased high in sulfate-dominated regions of North America and Europe. Our model-satellite comparison methodology shows that diurnal variability in aerosol loading is unimportant compared to sampling the model where the satellite has cloud-free observations, particularly in sulfate-dominated regions. Simulated sea salt burden and optical thickness are high by a factor of 2-3 relative to other models, and agreement between model and satellite over-ocean AOT is improved by reducing the model sea salt burden by a factor of 2. The best agreement in both AOT magnitude and variability occurs immediately downwind of the Saharan dust plume.

  10. What drives the aerosol distribution in Guangdong--the most developed province in Southern China?

    PubMed

    Li, Lili; Wang, Yunpeng

    2014-01-01

    This paper uses Moderate Resolution Imaging Spectroradiometer (MODIS) data to investigate the spatial and temporal variations of aerosol optical thickness (AOT) over Guangdong, the most developed province in China, during 2010-2012. Linear regression and self-organizing maps (SOM) are used to investigate the relationship between AOT and its affecting factors, including Normalized Difference Vegetation Index (NDVI), elevation, urbanized land fraction, and several socio-economic variables. Results show that the highest values of τ 0.55 mainly occur over the rapidly-developing Pearl River Delta (PRD) region and the eastern coast. Seasonal averaged AOT is highest in summer (0.416), followed by spring (0.351), winter (0.292), and autumn (0.254). From unary linear regression and SOM analysis, AOT is shown to be strongly negatively correlated to NDVI (R(2) = 0.782) and elevation (R(2) = 0.731), and positively correlated with socio-economic factors, especially GDP, industry and vehicle density (R(2) above 0.73), but not primary industry. Multiple linear regression between AOT and the contributing factors shows much higher R(2) values (>0.8), indicative of the clear relationships between AOT and variables. This study illustrates that human activities have strong impacts on aerosols distribution in Guangdong Province. Economic and industrial developments, as well as vehicle density, are the main controlling factors on aerosol distribution. PMID:25096216

  11. What drives the aerosol distribution in Guangdong - the most developed province in Southern China?

    NASA Astrophysics Data System (ADS)

    Li, Lili; Wang, Yunpeng

    2014-08-01

    This paper uses Moderate Resolution Imaging Spectroradiometer (MODIS) data to investigate the spatial and temporal variations of aerosol optical thickness (AOT) over Guangdong, the most developed province in China, during 2010-2012. Linear regression and self-organizing maps (SOM) are used to investigate the relationship between AOT and its affecting factors, including Normalized Difference Vegetation Index (NDVI), elevation, urbanized land fraction, and several socio-economic variables. Results show that the highest values of τ0.55 mainly occur over the rapidly-developing Pearl River Delta (PRD) region and the eastern coast. Seasonal averaged AOT is highest in summer (0.416), followed by spring (0.351), winter (0.292), and autumn (0.254). From unary linear regression and SOM analysis, AOT is shown to be strongly negatively correlated to NDVI (R2 = 0.782) and elevation (R2 = 0.731), and positively correlated with socio-economic factors, especially GDP, industry and vehicle density (R2 above 0.73), but not primary industry. Multiple linear regression between AOT and the contributing factors shows much higher R2 values (>0.8), indicative of the clear relationships between AOT and variables. This study illustrates that human activities have strong impacts on aerosols distribution in Guangdong Province. Economic and industrial developments, as well as vehicle density, are the main controlling factors on aerosol distribution.

  12. An electron magnetic resonance study of the photoionization of a series of N-alkylphenothiazines in AOT reverse micelles

    SciTech Connect

    Kang, Young Soo; McManus, H.J.D.; Kevan, L.

    1992-10-15

    N-Alkylphenothiazines (PC{sub n}, n=1,3,6,9,12,16) were photoirradiated in sodium bis(2-ethyl-1-hexyl) sulfosuccinate (aerosol octyl or AOT) reverse micelles to study the photoionization efficiency as a function of the interior water pool size and the location of the phenothiazine chromophore with respect to the AOT/D{sub 2}O interface. To optimize the photoyield, the dimensions of the occluded water pool were varied by changing the ratio of the number of water molecules to surfactant monomers. The photoyield shows a dependence on the length of the pendant alkyl chain. The highest photoyield, measured by electron spin resonance, is obtained for w{sub 0}=5 (w{sub 0} = [D{sub 2}O]/[AOT]); it decreases as the interior water pool size is increased. This observation is interpreted as showing that hydration of the sodium countercation with increasing interior water pool results in an increase of the anionic charge of the interface which increases the barrier for electron transmission. Electron spin echo modulation studies in D{sub 2}O show that the deuteron modulation depth increases as the size of the interior water pool increases but shows only a weak dependence on the alkyl chain length. Electron nuclear double resonance (ENDOR) studies show that the proton density in the vicinity of the paramagnetic cationic radical decreases as the size of the interior water pool increases. The ENDOR data do not show any significant dependence on the length of the pendant alkyl chain. Consequently, optimization of the charge separation of the photoproducts is best achieved by minimizing the size of the interior water pool. 38 refs., 7 figs.

  13. Electron processes in AOT reverse micelles. Part 2. Influence of oil phase. Pulse radiolysis study

    NASA Astrophysics Data System (ADS)

    Gebicki, J. L.; Bednarek, P.

    2000-11-01

    Reverse micellar systems formed of AOT, i.e. sodium bis(2-ethyl-1-hexyl) sulfo-succinate, in different hydrocarbons, without water, dry micelles, and in the presence of water, wet micelles, have been studied by means of pulse radiolysis. Different localization sites of hydrated electron within wet reverse micelle including a triad e aq-/Na +/SO 3- rad (absorption band peaking around 610 nm) are proposed and discussed to explain the influence of the ratio [water]/[AOT] and of the kind of alkane on the position and half-width of the absorption spectrum of the hydrated electron. Sulfite radical, necessary to form such triad, is released as a result of electron interaction with AOT molecule within reverse micelles (RM) containing water. A product of direct electron attachment to AOT molecule, AOT radical anion, has been observed spectrophotometrically only in dry AOT RM at ambient temperature (absorption band peaking around 330 nm).

  14. An 11-year global gridded aerosol optical thickness reanalysis (v1.0) for atmospheric and climate sciences

    NASA Astrophysics Data System (ADS)

    Lynch, Peng; Reid, Jeffrey S.; Westphal, Douglas L.; Zhang, Jianglong; Hogan, Timothy F.; Hyer, Edward J.; Curtis, Cynthia A.; Hegg, Dean A.; Shi, Yingxi; Campbell, James R.; Rubin, Juli I.; Sessions, Walter R.; Turk, F. Joseph; Walker, Annette L.

    2016-04-01

    While stand alone satellite and model aerosol products see wide utilization, there is a significant need in numerous atmospheric and climate applications for a fused product on a regular grid. Aerosol data assimilation is an operational reality at numerous centers, and like meteorological reanalyses, aerosol reanalyses will see significant use in the near future. Here we present a standardized 2003-2013 global 1 × 1° and 6-hourly modal aerosol optical thickness (AOT) reanalysis product. This data set can be applied to basic and applied Earth system science studies of significant aerosol events, aerosol impacts on numerical weather prediction, and electro-optical propagation and sensor performance, among other uses. This paper describes the science of how to develop and score an aerosol reanalysis product. This reanalysis utilizes a modified Navy Aerosol Analysis and Prediction System (NAAPS) at its core and assimilates quality controlled retrievals of AOT from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Multi-angle Imaging SpectroRadiometer (MISR) on Terra. The aerosol source functions, including dust and smoke, were regionally tuned to obtain the best match between the model fine- and coarse-mode AOTs and the Aerosol Robotic Network (AERONET) AOTs. Other model processes, including deposition, were tuned to minimize the AOT difference between the model and satellite AOT. Aerosol wet deposition in the tropics is driven with satellite-retrieved precipitation, rather than the model field. The final reanalyzed fine- and coarse-mode AOT at 550 nm is shown to have good agreement with AERONET observations, with global mean root mean square error around 0.1 for both fine- and coarse-mode AOTs. This paper includes a discussion of issues particular to aerosol reanalyses that make them distinct from standard meteorological reanalyses, considerations for extending such a reanalysis outside of the NASA A-Train era, and examples of how

  15. Development studies towards an 11-year global gridded aerosol optical thickness reanalysis for climate and applied applications

    NASA Astrophysics Data System (ADS)

    Lynch, P.; Reid, J. S.; Westphal, D. L.; Zhang, J.; Hogan, T. F.; Hyer, E. J.; Curtis, C. A.; Hegg, D. A.; Shi, Y.; Campbell, J. R.; Rubin, J. I.; Sessions, W. R.; Turk, F. J.; Walker, A. L.

    2015-12-01

    While standalone satellite and model aerosol products see wide utilization, there is a significant need in numerous climate and applied applications for a fused product on a regular grid. Aerosol data assimilation is an operational reality at numerous centers, and like meteorological reanalyses, aerosol reanalyses will see significant use in the near future. Here we present a standardized 2003-2013 global 1° × 1° and 6 hourly modal aerosol optical thickness (AOT) reanalysis product. This dataset can be applied to basic and applied earth system science studies of significant aerosol events, aerosol impacts on numerical weather prediction, and electro-optical propagation and sensor performance, among other uses. This paper describes the science of how to develop and score an aerosol reanalysis product. This reanalysis utilizes a modified Navy Aerosol Analysis and Prediction System (NAAPS) at its core and assimilates quality controlled retrievals of AOT from the Moderate Resolution Imaging Spectroradiometer (MODIS) on Terra and Aqua and the Multi-angle Imaging SpectroRadiometer (MISR) on Terra. The aerosol source functions, including dust and smoke, were regionally tuned to obtain the best match between the model fine and coarse mode AOTs and the Aerosol Robotic Network (AERONET) AOTs. Other model processes, including deposition, were tuned to minimize the AOT difference between the model and satellite AOT. Aerosol wet deposition in the tropics is driven with satellite retrieved precipitation, rather than the model field. The final reanalyzed fine and coarse mode AOT at 550 nm is shown to have good agreement with AERONET observations, with global mean root mean square error around 0.1 for both fine and coarse mode AOTs. This paper includes a discussion of issues particular to aerosol reanalyses that make them distinct from standard meteorological reanalyses, considerations for extending such a reanalysis outside of the NASA A-Train era, and examples of how the

  16. Electrical conductivity and permittivity of water-AOT-n-heptane microemulsions

    SciTech Connect

    Arcoleo, V.; Goffredi, M.; Liveri, V.T.

    1995-11-01

    Measurements of the electrical conductivity and of the complex permittivity of water-sodium bis(2-ethylhexyl) sulfosuccinate (AOT)-n-heptane microemulsions are reported. The experimental results are rationalized in terms of a hopping mechanism of AOT anions within clusters of reversed micelles. The dependence of the hopping rate and of the cluster dimensions upon the ratio [water]/[AOT] and temperature is discussed.

  17. Toward Unified Satellite Climatology of Aerosol Properties. 3. MODIS Versus MISR Versus AERONET

    NASA Technical Reports Server (NTRS)

    Mishchenko, Michael I.; Liu, Li; Geogdzhayev, Igor V.; Travis, Larry D.; Cairns, Brian; Lacis, Andrew A.

    2010-01-01

    We use the full duration of collocated pixel-level MODIS-Terra and MISR aerosol optical thickness (AOT) retrievals and level 2 cloud-screened quality-assured AERONET measurements to evaluate the likely individual MODIS and MISR retrieval accuracies globally over oceans and land. We show that the use of quality-assured MODIS AOTs as opposed to the use of all MODIS AOTs has little effect on the resulting accuracy. The MODIS and MISR relative standard deviations (RSTDs) with respect to AERONET are remarkably stable over the entire measurement record and reveal nearly identical overall AOT performances of MODIS and MISR over the entire suite of AERONET sites. This result is used to evaluate the likely pixel-level MODIS and MISR performances on the global basis with respect to the (unknown) actual AOTs. For this purpose, we use only fully compatible MISR and MODIS aerosol pixels. We conclude that the likely RSTDs for this subset of MODIS and MISR AOTs are 73% over land and 30% over oceans. The average RSTDs for the combined [AOT(MODIS)+AOT(MISR)]/2 pixel-level product are close to 66% and 27%, respectively, which allows us to recommend this simple blend as a better alternative to the original MODIS and MISR data. These accuracy estimates still do not represent the totality of MISR and quality-assured MODIS pixel-level AOTs since an unaccounted for and potentially significant source of errors is imperfect cloud screening. Furthermore, many collocated pixels for which one of the datasets reports a retrieval, whereas the other one does not may also be problematic.

  18. Investigations of the March 2006 African dust storm using ground-based column-integrated high spectral resolution infrared (8-13 μm) and visible aerosol optical thickness measurements: 1. Measurement procedures and results

    NASA Astrophysics Data System (ADS)

    Thomas, M.; Gautier, C.; Ricchiazzi, P.

    2009-06-01

    The infrared (IR) aerosol optical thickness (AOT) spectra of Saharan dust measured during the Portable Infrared Aerosol Transmission Experiment (PIRATE) are reported. Saharan dust optical thickness (extinction) spectra from 8 to 13 μm were obtained using column-integrated solar transmission measurements in Puerto Rico in July 2005 and Senegal in January and March 2006 (during a dust plume) using a Fourier transform infrared (FTIR) spectrometer. The FTIR measured the solar spectral irradiance in the IR in the presence of Saharan dust, and the AOT was determined by comparing the measured spectra to modeled downwelling spectra without dust for the same atmospheric temperature profile, solar zenith angle, water vapor, and ozone concentrations. The modeled dust-free spectra are generated using the Santa Barbara Disort Atmospheric Radiative Transfer (SBDART) program. The measured dust AOT is compared with modeled AOT spectra obtained using Mie theory with dust indices of refraction from Volz and Fouquart with assumed lognormal size distributions. When the visible AOT values from nearby Aerosol Robotic Network (AERONET) sensors are compared to the IR AOT values, results from various dust loadings show that the IR dust AOT at 9.5 μm is typically only one third that of the visible (670 nm) dust AOT, but there is some evidence that this ratio could increase for larger dust size distributions. The surface IR dust forcing is determined to be about -0.4 W/m2 by summing the dusty and clear irradiance differences.

  19. Analyzing signatures of aerosol-cloud interactions from satelliteretrievals and the GISS GCM to constrain the aerosol indirecteffect

    SciTech Connect

    Menon, S.; Del Genio, A.D.; Kaufman, Y.; Bennartz, R.; Koch, D.; Loeb, N.; Orlikowski, D.

    2007-10-01

    Evidence of aerosol-cloud interactions are evaluated using satellite data from MODIS, CERES, AMSR-E, reanalysis data from NCEP and data from the NASA Goddard Institute for Space Studies climate model. We evaluate a series of model simulations: (1) Exp N- aerosol direct radiative effects; (2) Exp C- Like Exp N but with aerosol effects on liquid-phase cumulus and stratus clouds; (3) Exp CN- Like Exp C but with model wind fields nudged to reanalysis data. Comparison between satellite-retrieved data and model simulations for June to August 2002, over the Atlantic Ocean indicate the following: a negative correlation between aerosol optical thickness (AOT) and cloud droplet effective radius (R{sub eff}) for all cases and satellite data, except for Exp N; a weak but negative correlation between liquid water path (LWP) and AOT for MODIS and CERES; and a robust increase in cloud cover with AOT for both MODIS and CERES. In all simulations, there is a positive correlation between AOT and both cloud cover and LWP (except in the case of LWP-AOT for Exp CN). The largest slopes are obtained for Exp N, implying that meteorological variability may be an important factor. The main fields associated with AOT variability in NCEP/MODIS data are warmer temperatures and increased subsidence for less clean cases, not well captured by the model. Simulated cloud fields compared with an enhanced data product from MODIS and AMSR-E indicate that model cloud thickness is over-predicted and cloud droplet number is within retrieval uncertainties. Since LWP fields are comparable this implies an under-prediction of R{sub eff} and thus an over-prediction of the indirect effect.

  20. MASTER: PSN in PGC858421 and OTs

    NASA Astrophysics Data System (ADS)

    Tiurina, N.; Balanutsa, P.; Lipunov, E. Popova V.; Buckley, D.; Gorbovskoy, E.; Kuznetsov, A.; Kornilov, V.; Vlasenko, D.; Gress, O.; Shurpakov, S.; Potter, S.; Kniazev, A.

    2016-07-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 14h 47m 32.66s -19d 12m 42.1s on 2016-07-09.87385 UT. PSN unfiltered magnitude is (limit 19.8m).

  1. 75 FR 51169 - OTS Minority Depository Institutions Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-18

    ... Office of Thrift Supervision OTS Minority Depository Institutions Advisory Committee AGENCY: Department of the Treasury, Office of Thrift Supervision (OTS). ACTION: Notice. SUMMARY: The Charter for the OTS..., Office of Thrift Supervision, 1700 G Street, NW., Washington, DC 20552. SUPPLEMENTARY INFORMATION:...

  2. Impact of Satellite Viewing-Swath Width on Global and Regional Aerosol Optical Thickness Statistics and Trends

    NASA Technical Reports Server (NTRS)

    Colarco, P. R.; Kahn, R. A.; Remer, L. A.; Levy, R. C.

    2014-01-01

    We use the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite aerosol optical thickness (AOT) product to assess the impact of reduced swath width on global and regional AOT statistics and trends. Alongtrack and across-track sampling strategies are employed, in which the full MODIS data set is sub-sampled with various narrow-swath (approximately 400-800 km) and single pixel width (approximately 10 km) configurations. Although view-angle artifacts in the MODIS AOT retrieval confound direct comparisons between averages derived from different sub-samples, careful analysis shows that with many portions of the Earth essentially unobserved, spatial sampling introduces uncertainty in the derived seasonal-regional mean AOT. These AOT spatial sampling artifacts comprise up to 60%of the full-swath AOT value under moderate aerosol loading, and can be as large as 0.1 in some regions under high aerosol loading. Compared to full-swath observations, narrower swath and single pixel width sampling exhibits a reduced ability to detect AOT trends with statistical significance. On the other hand, estimates of the global, annual mean AOT do not vary significantly from the full-swath values as spatial sampling is reduced. Aggregation of the MODIS data at coarse grid scales (10 deg) shows consistency in the aerosol trends across sampling strategies, with increased statistical confidence, but quantitative errors in the derived trends are found even for the full-swath data when compared to high spatial resolution (0.5 deg) aggregations. Using results of a model-derived aerosol reanalysis, we find consistency in our conclusions about a seasonal-regional spatial sampling artifact in AOT Furthermore, the model shows that reduced spatial sampling can amount to uncertainty in computed shortwave top-ofatmosphere aerosol radiative forcing of 2-3 W m(sup-2). These artifacts are lower bounds, as possibly other unconsidered sampling strategies would perform less well. These results

  3. Long term characterization of aerosol optical properties: Implications for radiative forcing over the desert region of Jodhpur, India

    NASA Astrophysics Data System (ADS)

    Bhaskar, V. Vizaya; Safai, P. D.; Raju, M. P.

    2015-08-01

    AOT data for eight years period (2004-2012) using the MICROTOPS II Sun photometer has been used to study the wavelength dependent optical characteristics of aerosols over Jodhpur, situated in the desert region in NW India. The daily mean AOT at 500 nm for the present study period was 0.66 ± 0.14 with an average Angstrom exponent as 0.71 ± 0.20. Linear regression analysis of monthly AOT and Angstrom Exponent indicated an increasing trend of both. Seasonal variations of daily AOT and α as well as spectral dependence of seasonal mean AOT are presented. Diurnal variation of AOT and α in different season is studied. Impact of dust storm events on the aerosol characteristics over Jodhpur during the study period is studied. AOT values derived from MICROTOPS II were cross checked with Sun Sky Radiometer (Model POM-01, Prede Inc.) data for the period from May 2011 to April 2012 and were found to be in good agreement. Short wave aerosol radiative forcing (ARF) was computed for one year period of May 2011 to April 2012. Spectral variation of AOT, SSA and ASP showed more AOT and ASP during pre monsoon period when SSA was comparatively low; indicating towards more prevalence of coarse size absorbing dust in this period. The ARF at SUF and TOA was negative during all the seasons indicating dominance of scattering type aerosols mainly dust particles whereas that at ATM was positive in all the seasons indicating heating of the atmosphere, especially more during pre monsoon (+40.5 W/m2) than during rest of the year (+19.5 W/m2). A high degree of correlation between ARF at the SUF with AOT (R2 = 0.94) indicated that ARF is a strong function of AOT. The radiative forcing efficiency inferred to scattering nature of aerosols at SUF (-4.2 W/m2/AOD) and TOA (-63.2 W/m2/AOD) indicating cooling at surface and top of the atmosphere whereas, there was warming of the atmosphere in between (+59 W/m2/AOD). The atmospheric heating rates varied from 0.49 K/day in post monsoon to 1.13 K/day in

  4. Optical properties of aerosol contaminated cloud derived from MODIS instrument

    NASA Astrophysics Data System (ADS)

    Mei, Linlu; Rozanov, Vladimir; Lelli, Luca; Vountas, Marco; Burrows, John P.

    2016-04-01

    The presence of absorbing aerosols above/within cloud can reduce the amount of up-welling radiation in visible (VIS) and short-wave infrared and darken the spectral reflectance when compared with a spectrum of a clean cloud observed by satellite instruments (Jethva et al., 2013). Cloud properties retrieval for aerosol contaminated cases is a great challenge. Even small additional injection of aerosol particles into clouds in the cleanest regions of Earth's atmosphere will cause significant effect on those clouds and on climate forcing (Koren et al., 2014; Rosenfeld et al., 2014) because the micro-physical cloud process are non-linear with respect to the aerosol loading. The current cloud products like Moderate Resolution Imaging Spectroradiometer (MODIS) ignoring the aerosol effect for the retrieval, which may cause significant error in the satellite-derived cloud properties. In this paper, a new cloud properties retrieval method, considering aerosol effect, based on the weighting-function (WF) method, is presented. The retrieval results shows that the WF retrieved cloud properties (e.g COT) agrees quite well with MODIS COT product for relative clear atmosphere (AOT ≤ 0.4) while there is a large difference for large aerosol loading. The MODIS COT product is underestimated for at least 2 - 3 times for AOT>0.4, and this underestimation increases with the increase of AOT.

  5. On relationship between aerosols and PM2.5

    NASA Astrophysics Data System (ADS)

    Sano, Itaru; Mukai, Sonoyo; Nakata, Makiko

    2015-04-01

    Since aerosol optical thickness (AOT) is a key parameter of aerosols and description of the Earth's radiation budget, it is widely measured from ground sun photometer network NASA/AERONET [Holben et al., 1998] and from satellite. Fine and surface level aerosol particle called PM2.5, whose diameter is 2.5 μ m or less, is a well-known parameter for understanding polluted level of air. Smirnov et al. reported a good agreement between ground based AERONET AOT (870 nm) and dust concentrations at Barbados [Smirnov et al., 2000]. Wang and Christopher founded a good correlation between satellite based MODIS AOT product and PM2.5 in Alabama area [Wang and 2003]. Long range transported dusts, particularly Asian dust events, are easy to change the vertical profile of aerosol extinction. The vertical profile is important to estimate PM information because both AOT information measured from ground or satellite are integrated value of aerosol extinction from ground to space, i.e. columnar AOT. Thus, we have also proposed correlations between ground level PM2.5 and AERONET AOT (670 nm) in two cases of ordinary air condition and dusty days [Sano et al., 2010]. In this work, we investigate the relationship between PM2.5 and AERONET AOT considering LIDAR measurements. Note that all of instruments are set up at the roof of the University building (50 m) and collocated in 10 m area. Surface-level AOT is derived from AERONET AOT multiplied by an averaged vertical aerosol extinction given by LIDAR. Note that the definition of surface-level AOT in this work is assumed as AOT up to 500 m height. Introduction of surface-level AOT enables to avoid the contamination of dusty aerosol signal existing at high altitude from columnar AOT. The cloud aerosol imager (CAI) on GOSAT satellite has four observing wavelengths, 380, 670, 870 nm, and 1.6 μ m. In this work three channels are selected to estimate aerosol information. Look-up table (LUT) method is applied to estimate the optical properties

  6. Statistical characteristics of atmospheric aerosol as determined from AERONET measurements

    NASA Astrophysics Data System (ADS)

    Yoon, Jongmin; Kokhanovsky, Alexander

    2015-04-01

    Seasonal means and standard deviations of column-integrated aerosol optical properties (e.g. spectral aerosol optical thickness (AOT), single scattering albedo, phase function, Ångström exponent, volume particle size distribution, complex refractive index, absorbing aerosol optical thickness) from several Aerosol Robotic Network (AERONET) sites located in typical aerosol source and background regions are investigated (Holben et al., 1998). The AERONET program is an inclusive network of ground-based sun-photometers that measure atmospheric aerosol optical properties (http://aeronet.gsfc.nasa.gov/). The results can be used for improving the accuracy of satellite-retrieved AOT, assessments of the global aerosol models, studies of atmospheric pollution and aerosol radiative forcing on climate. We have paid a special attention to several AERONET sites that are Mexico_City (Mexico), Alta_Floresta (Brazil), Avignon (France), Solar_Village (Saudi Arabia), and Midway_Island (Pacific) representative for industrial/urban, biomass burning, rural, desert dust and oceanic aerosols, respectively. We have found that the optical and microphysical aerosol properties are highly dependent on the local aerosol emission sources and seasonal meteorological conditions.

  7. Using Airborne High Spectral Resolution Lidar Data to Evaluate Combined Active Plus Passive Retrievals of Aerosol Extinction Profiles

    NASA Technical Reports Server (NTRS)

    Burton, S. P.; Ferrare, R. A.; Kittaka, C.; Hostetler, C. A.; Hair, J. W.; Obland, M. D.; Rogers, R. R.; Cook, A. L.; Haper, D. B.

    2008-01-01

    Aerosol extinction profiles are derived from backscatter data by constraining the retrieval with column aerosol optical thickness (AOT), for example from coincident MODIS observations and without reliance on a priori assumptions about aerosol type or optical properties. The backscatter data were acquired with the NASA Langley High Spectral Resolution Lidar (HSRL). The HSRL also simultaneously measures extinction independently, thereby providing an ideal data set for evaluating the constrained retrieval of extinction from backscatter. We will show constrained extinction retrievals using various sources of column AOT, and examine comparisons with the HSRL extinction measurements and with a similar retrieval using data from the CALIOP lidar on the CALIPSO satellite.

  8. Extension and statistical analysis of the GACP aerosol optical thickness record

    NASA Astrophysics Data System (ADS)

    Geogdzhayev, Igor V.; Mishchenko, Michael I.; Li, Jing; Rossow, William B.; Liu, Li; Cairns, Brian

    2015-10-01

    The primary product of the Global Aerosol Climatology Project (GACP) is a continuous record of the aerosol optical thickness (AOT) over the oceans. It is based on channel-1 and -2 radiance data from the Advanced Very High Resolution Radiometer (AVHRR) instruments flown on successive National Oceanic and Atmospheric Administration (NOAA) platforms. We extend the previous GACP dataset by four years through the end of 2009 using NOAA-17 and -18 AVHRR radiances recalibrated against MODerate resolution Imaging Spectroradiometer (MODIS) radiance data, thereby making the GACP record almost three decades long. The temporal overlap of over three years of the new NOAA-17 and the previous NOAA-16 record reveals an excellent agreement of the corresponding global monthly mean AOT values, thereby confirming the robustness of the vicarious radiance calibration used in the original GACP product. The temporal overlap of the NOAA-17 and -18 instruments is used to introduce a small additive adjustment to the channel-2 calibration of the latter resulting in a consistent record with increased data density. The Principal Component Analysis (PCA) of the newly extended GACP record shows that most of the volcanic AOT variability can be isolated into one mode responsible for ~ 12% of the total variance. This conclusion is confirmed by a combined PCA analysis of the GACP, MODIS, and Multi-angle Imaging SpectroRadiometer (MISR) AOTs during the volcano-free period from February 2000 to December 2009. We show that the modes responsible for the tropospheric AOT variability in the three datasets agree well in terms of correlation and spatial patterns. A previously identified negative AOT trend which started in the late 1980s and continued into the early 2000s is confirmed. Its magnitude and duration indicate that it was caused by changes in tropospheric aerosols. The latest multi-satellite segment of the GACP record shows that this trend tapered off, with no noticeable AOT change after 2002. This

  9. Extension and Statistical Analysis of the GACP Aerosol Optical Thickness Record.

    NASA Technical Reports Server (NTRS)

    Geogdzhayev, Igor V.; Mishchenko, Michael I.; Li, Jing; Rossow, William B.; Liu, Li; Cairns, Brian

    2015-01-01

    The primary product of the Global Aerosol Climatology Project (GACP) is a continuous record of the aerosol optical thickness (AOT) over the oceans. It is based on channel-1 and -2 radiance data from the Advanced Very High Resolution Radiometer (AVHRR) instruments flown on successive National Oceanic and Atmospheric Administration (NOAA) platforms. We extend the previous GACP dataset by four years through the end of 2009 using NOAA-17 and -18 AVHRR radiances recalibrated against MODerate resolution Imaging Spectroradiometer (MODIS) radiance data, thereby making the GACP record almost three decades long. The temporal overlap of over three years of the new NOAA-17 and the previous NOAA-16 record reveals an excellent agreement of the corresponding global monthly mean AOT values, thereby confirming the robustness of the vicarious radiance calibration used in the original GACP product. The temporal overlap of the NOAA-17 and -18 instruments is used to introduce a small additive adjustment to the channel-2 calibration of the latter resulting in a consistent record with increased data density. The Principal Component Analysis (PCA) of the newly extended GACP record shows that most of the volcanic AOT variability can be isolated into one mode responsible for 12% of the total variance. This conclusion is confirmed by a combined PCA analysis of the GACP, MODIS, andMulti-angle Imaging SpectroRadiometer (MISR) AOTs during the volcano-free period fromFebruary 2000 to December 2009.We show that the modes responsible for the tropospheric AOT variability in the three datasets agree well in terms of correlation and spatial patterns. A previously identified negative AOT trend which started in the late 1980s and continued into the early 2000s is confirmed. Its magnitude and duration indicate that it was caused by changes in tropospheric aerosols. The latest multi-satellite segment of the GACP record shows that this trend tapered off, with no noticeable AOT change after 2002. This

  10. Higher order structure of proteins solubilized in AOT reverse micelles.

    PubMed

    Naoe, Kazumitsu; Noda, Kazuki; Kawagoe, Mikio; Imai, Masanao

    2004-11-15

    The higher order structure of proteins solubilized in an bis(2-ethylhexyl) sulfosuccinate sodium (AOT) reverse micellar system was investigated. From circular dichroic (CD) measurement, CD spectra of cytochrome c, which is solubilized at the interface of reverse micelles, markedly changed on going from buffer solution to the reverse micellar solution, and the ellipticity values in the far- and near-UV regions decreased with decreasing the water content (W0: molar ratio of water to AOT), indicating that the secondary and tertiary structures of cytochrome c changed with the water content. The ellipticity of ribonuclease A, which is solubilized in the center of micellar water pool, in the near-UV region was dependent on W0 and became minimum when W0 of ca. 8 while the ellipticity in the far-UV region was almost constant, indicating that the tertiary structure of ribonuclease A was affected by the water content, but the secondary structure was conserved. The degree of curvature of the micellar interface appears to influence the protein structure because the reverse micelle size is linearly proportional to the W0 value. As evidence of this, when the micelle size was comparable to the protein's dimensions, the structures were more affected by the water content. Judging from the dependence of the factor influencing the protein structure on the protein species, the location of solubilized protein in reverse micelles is significantly related to whether the protein structure in the system is affected by the micellar interface. In the cases of cytochrome c and lysozyme, the ellipticity against W0 was dependent on the AOT concentration. In contrast, ribonuclease A gave very similar ellipticity values whatever the AOT concentration. In the n-hexane micellar system, cytochrome c exhibited lower ellipticity values and ribonuclease A in the lower W0 range (W0

  11. Urban aerosol pollution assessment in Russian largest cities

    NASA Astrophysics Data System (ADS)

    Malinina, Elizaveta; Chubarova, Natalia; Sviridenkov, Mikhail

    2015-04-01

    We assessed the aerosol pollution in 51 Russian largest cities, which are located in different climatic zones with various level of urban pollution using the aerosol optical thickness (AOT) at 550 nm from MODIS data with a spatial resolution 1°×1°during the warm period of 2000-2013. For better understanding of MODIS radiometers quality of AOT data over Russia the comparisons between AERONET data and MODIS data were fulfilled. They showed a good quality of the MODIS data and its possibility to detect an urban pollution from space. As a characteristic of urban aerosol pollution we used the difference between AOT in the city and the background value of AOT in the nearby region. The research showed, that urban aerosol pollution in Russian cities varied from 0.01 to 0.08. Besides, more precise assessment of urban aerosol pollution in Moscow was done basing on the AERONET network data in two sites at Moscow University Meteorological Observatory (MO) and at the Zvenigorod Scientific Station (ZSS). For the assessment the simultaneous measurements at these two sites during the period from September 2006 till July 2013 were taken. The average AOT difference in the visible spectrum (wavelength: 500 nm) between MO and ZSS, which could be used as pollution characteristic, is about 0.02. These results are similar to similar research, which had been made earlier for a shorter period. The difference between AOT at these two sites is the largest in winter and is about 0.03. In order to assess the dominating aerosol components in different cities we used the data of Russian network on emissions and concentrations of the main pollutants over the 1988-2011 period. For each city we evaluated the ratio of sulfur dioxide to nitrogen dioxide emissions and its trends to assess the dominating aerosol properties and temporal variability. As a result, the radiative forcing of urban aerosol pollution for different cities was evaluated. Depending on the location, the size and the level of

  12. Retrieval of particle size distribution from aerosol optical thickness using an improved particle swarm optimization algorithm

    NASA Astrophysics Data System (ADS)

    Mao, Jiandong; Li, Jinxuan

    2015-10-01

    Particle size distribution is essential for describing direct and indirect radiation of aerosols. Because the relationship between the aerosol size distribution and optical thickness (AOT) is an ill-posed Fredholm integral equation of the first type, the traditional techniques for determining such size distributions, such as the Phillips-Twomey regularization method, are often ambiguous. Here, we use an approach based on an improved particle swarm optimization algorithm (IPSO) to retrieve aerosol size distribution. Using AOT data measured by a CE318 sun photometer in Yinchuan, we compared the aerosol size distributions retrieved using a simple genetic algorithm, a basic particle swarm optimization algorithm and the IPSO. Aerosol size distributions for different weather conditions were analyzed, including sunny, dusty and hazy conditions. Our results show that the IPSO-based inversion method retrieved aerosol size distributions under all weather conditions, showing great potential for similar size distribution inversions.

  13. Assimilation of POLDER aerosol optical thickness into the LMDz-INCA model: Implications for the Arctic aerosol burden

    NASA Astrophysics Data System (ADS)

    Generoso, S.; BréOn, F.-M.; Chevallier, F.; Balkanski, Y.; Schulz, M.; Bey, I.

    2007-01-01

    The large spatial and temporal variability of atmospheric aerosol load makes it a challenge to quantify aerosol effect on climate. This study is one of the first attempts to apply data assimilation for the analysis of global aerosol distribution. Aerosol optical thickness (AOT) observed from the Polarization and Directionality of the Earth Reflectances (POLDER) spaceborne instrument are assimilated into a three-dimensional chemistry model. POLDER capabilities to distinguish between fine and coarse AOT are used to constrain them separately in the model. Observation and model errors are a key component of such a system and are carefully estimated on a regional basis using some of the high-quality surface observations from the Aerosol Robotic Network (AERONET). Other AERONET data provide an independent evaluation of the a posteriori fields. Results for the fine mode show improvements, in terms of reduction of root-mean-square errors, in most regions with the largest improvements found in the Mediterranean Sea and Eurasia. We emphasize the results for the Arctic, where there is growing evidence of a strong aerosol impact on climate, but a lack of regional and continuous aerosol monitoring. The a posteriori fields noticeably well reproduce the winter-spring "Arctic Haze" peak measured in Longyearbyen (15°E, 78°N) and typical seasonal variations in the Arctic region, where AOT increase by up to a factor of three between a posteriori and a priori. Enhanced AOT are found over a longer period in spring 2003 than in 1997, suggesting that the large Russian fires in 2003 have influenced the Arctic aerosol load.

  14. Investigations of the March 2006 African dust storm using ground-based column-integrated high spectral resolution infrared (8-13 μm) and visible aerosol optical thickness measurements: 2. Mineral aerosol mixture analyses

    NASA Astrophysics Data System (ADS)

    Thomas, M.; Gautier, C.

    2009-07-01

    The mineral aerosol mixture composition for the March 2006 Saharan dust storm is assessed in this paper on the basis of the analysis of visible to near-infrared (VIS-NIR) and infrared (IR) aerosol optical thickness (AOT) spectra obtained during the Portable Infrared Aerosol Transmission Experiment (PIRATE). The AOT spectra from 8 to 13 μm were determined using column-integrated solar transmission measurements using a Fourier transform infrared spectrometer. To determine the mineralogy and mixture composition of the dust, we determined the expected mineralogy of dust from the Algerian source region in a dust storm environment. Then we computed the modeled VIS-IR AOT spectra using Mie theory for external and internal mixtures. We compared the modeled VIS-NIR AOT spectra and derived index of refraction and single-scattering albedo with the measured values from AERONET and compared the modeled IR AOT spectra with the values from our IR measurements. The fit between the measured and modeled values was best when we used an extinction resonance correction to the Mie theory results to better account for the exact wavelengths and shapes of some of the AOT peaks for mineral particles. The mineralogy and mixture composition of the best dust model includes external mixtures, internal mixtures, and mineralogy dominated by quartz, illite, and calcite. The modeled mean radius was determined, and several modes were computed in agreement with AERONET results.

  15. MASTER OT 015347+303844 discovery

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Gorbovskoy, E.; Lipunov, V.; Kornilov, V.; Belinski, A.; Shatskiy, N.; Tyurina, N.; Kuvshinov, D.; Chazov, V.; Kuznetsov, A.; Zimnukhov, D.; Kornilov, M.; Tlatov, A.; Parhomenko, A. V.; Dormidontov, D.; Yurkov, V.; Sergienko, Yu.; Varda, D.; Krushinski, V.; Zalozhnih, I.; Kopytova, T.; Popov, A.; Ivanov, K.; Yazev, S.; Budnev, N.; Konstantinov, E.; Lenok, V.; Chuvalaev, O.; Poleschuk, V.; Gres, O.

    2010-10-01

    MASTER auto-detection system at Kislovodsk detected a new transient source at the position (R.A., Dec) = 01h 53m 47.24s , +30d 38m 44s.0 (J2000) with a typical uncertainty of 0.2" at 2010-10-01 23:25:48 (UT). The V magnitude is about 17.9 +-0.1 ( exposition 180s, m_lim = 19.0 ). The OT is seen at next 7 images up 2010-10-12 in R and V. OT is blue: R-V=1.43 at 2010-10-01.9 . There is no minor planet and any object brighter 21 mag in DSS at this place.

  16. Meridional Distribution of Aerosol Optical Thickness over the Tropical Atlantic Ocean

    NASA Technical Reports Server (NTRS)

    Kishcha, P.; Silva, Arlindo M.; Starobinets, B.; Long, C. N.; Kalashnikova, O.; Alpert, P.

    2015-01-01

    Previous studies showed that, over the global ocean, there is hemispheric asymmetry in aerosols and no noticeable asymmetry in cloud fraction (CF). In the current study, we focus on the tropical Atlantic (30 Deg N 30 Deg S) which is characterized by significant amounts of Saharan dust dominating other aerosol species over the North Atlantic. We found that, by contrast to the global ocean, over a limited area such as the tropical Atlantic, strong meridional asymmetry in dust aerosols was accompanied by meridional CF asymmetry. During the 10-year study period (July 2002 June 2012), NASA Aerosol Reanalysis (aka MERRAero) showed that, when the meridional asymmetry in dust aerosol optical thickness (AOT) was the most pronounced (particularly in July), dust AOT averaged separately over the tropical North Atlantic was one order of magnitude higher than dust AOT averaged over the tropical South Atlantic. In the presence of such strong meridional asymmetry in dust AOT in July, CF averaged separately over the tropical North Atlantic exceeded CF averaged over the tropical South Atlantic by 20%. Our study showed significant cloud cover, up to 0.8 - 0.9, in July along the Saharan Air Layer which contributed to above-mentioned meridional CF asymmetry. Both Multi-Angle Imaging SpectroRadiometer (MISR) measurements and MERRAero data were in agreement on seasonal variations in meridional aerosol asymmetry. Meridional asymmetry in total AOT over the Atlantic was the most pronounced between March and July, when dust presence over the North Atlantic was maximal. In September and October, there was no noticeable meridional asymmetry in total AOT and meridional CF distribution over the tropical Atlantic was almost symmetrical.

  17. Nighttime Aerosol Optical Thickness Retrievals Via the VIIRS Day/Night Band and the Effects of Lunar Contamination

    NASA Astrophysics Data System (ADS)

    McHardy, T. M.; Zhang, J.; Reid, J. S.; Miller, S. D.; Hyer, E. J.; Kuehn, R.

    2015-12-01

    Using Visible/Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) data, a method for retrieving aerosol optical thickness (AOT) values at night via the examination of the dispersion of radiance values above an artificial light source ,dubbed the "variance method", is presented. Based on the improvement of a previous algorithm, this updated method derives a semi-quantitative indicator of nighttime AOT using artificial light sources. Nighttime DNB AOT retrievals from the variance method are compared with an AOT value from late afternoon and early morning ground observations from four AErosol RObotic NETwork (AERONET) sites as well as column integrated from one High Spectral Resolution Lidar (HSRL) site at Huntsville, AL during the NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign, providing full diel coverage. An emphasis is placed on sensitivity studies performed to examine the effects of lunar illumination on VIIRS DNB AOT retrievals made via the variance method. Although the small sample size of this study limits the conclusiveness thus far, investigation reveals that lunar contamination may have a smaller impact on VIIRS DNB AOT retrievals made using this method than previously thought. Preliminary results suggest that artificial light sources can be used for estimating regional and global nighttime aerosol distributions in the future.

  18. Current Status of Suomi NPP VIIRS Aerosol Products

    NASA Astrophysics Data System (ADS)

    Kondragunta, S.; Laszlo, I.; Liu, H.; Zhang, H.; Huang, J.; Remer, L. A.; Ciren, P.; Huang, H.

    2013-12-01

    The Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument was launched on October 28, 2011. It provides Aerosol Optical Thickness (AOT) at two different spatial resolutions: a pixel level (~750 m at nadir) product called the Intermediate Product (IP) and an aggregated (~6 km at nadir) product called the Environmental Data Record (EDR). The VIIRS AOT is expected to provide continuity to the 10-km Aqua and Terra MODIS (Moderate resolution Imaging Spectroradiometer) AOT products that the air quality and public health community has been using. The VIIRS aerosol product suite also includes less mature products such as Suspended Matter (SM) and Aerosol Particle Size Parameter (APSP). An extensive validation of VIIRS best quality aerosol products with ground based L1.5 AERONET data shows that the AOT EDR product has an accuracy/precision of -0.01/0.11 and 0.01/0.08 over land and ocean respectively. Globally, VIIRS mean AOT EDR (0.20) is similar to Aqua MODIS (0.16) with some important regional and seasonal differences. Analysis of SM shows that the algorithm predominantly picks smoke both over land and ocean which is not in agreement with retrievals from Multi-angle Imaging SpectroRadiometer (MISR) and Cloud Aerosol Lidar and Infrared Pathfinder Space Observations (CALIPSO). Similarly, the Angstrom Exponent (AE) retrieval used as a proxy for particle size has no skill over land and only a marginal skill over ocean when compared to AERONET; although a bias of ~0.2 for over ocean retrievals meets specification (0.3), the correlation is low and the standard deviation is ~0.6 and does not meet specification (0.3). This evaluation places the VIIRS AOT product at the provisional maturity level (product is validated, may contain some errors, and ready for operational evaluation). However, several algorithm updates which include a better approach to retrieve surface reflectance are forthcoming. Current status of the aerosol

  19. Study of AOT-stabilized microemulsions of urea dispersed in carbon tetrachloride

    NASA Astrophysics Data System (ADS)

    Ruggirello, A.; Turco Liveri, V.

    2003-03-01

    Measurements of some physico-chemical properties (density, viscosity, permittivity) of the urea/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/CCl 4 system as a function of the volume fraction of the dispersed phase (0< Φ<0.7) at various urea to AOT molar ratio ( Rurea) have been carried out at 25 °C. The experimental data analysis are consistent with the hypothesis that urea is entrapped as small-size molecular clusters within the hydrophilic core of the AOT reversed micelles and that this structure is preserved well above a threshold Φ value where a percolative transition occurs. Besides, X-ray diffraction spectra of samples at Φ=1, obtained by complete evaporation under vacuum of the apolar solvent of urea/AOT/CCl 4 solutions, indicates that, even in the typical two-dimensional hexagonal structure of AOT liquid crystals, urea is encapsulated as uni-dimensional molecular clusters.

  20. Development of the simple and sensitive method for lipoxygenase assay in AOT/isooctane reversed micelles.

    PubMed

    Park, Kyung Min; Kim, Yu Na; Choi, Seung Jun; Chang, Pahn-Shick

    2013-06-01

    In this study, we investigated the possibility of reversed micelles, widely used as an enzyme reactor for lipases, for the determination of lipoxygenase activity. Although it is rapid and simple, reversed micelles have some limitations, such as interference by UV-absorbing materials and surfactant. Lipoxygenase activity in the reversed micelles was determined by reading the absorbance of the lipid hydroperoxidation product (conjugated diene) at 234 nm. Among surfactants and organic media, AOT and isooctane were most effective for the dioxygenation of linoleic acid in reversed micelles. The strong absorbance of AOT in the UV region is a major obstacle for the direct application of the AOT/isooctane reversed micelles to lipoxygenase activity determination. To prevent interference by AOT, we added an AOT removal step in the procedure for lipoxygenase activity determination in reversed micelles. The lipoxygenase activity was dependent on water content, and maximum activity was obtained at an R-value of 10. PMID:23411168

  1. FT-IR and dielectric study of water/AOT liquid crystals

    NASA Astrophysics Data System (ADS)

    Calandra, P.; Caponetti, E.; Chillura Martino, D.; D'Angelo, P.; Minore, A.; Turco Liveri, V.

    2000-04-01

    In order to explore the influence of microwave radiation on highly viscous microheterogeneous systems, the evolution of structural and dynamical properties of the water/sodium bis(2-ethylhexyl) sulfosuccinate (AOT) liquid crystals as a function of the molar ratio R ( R=[water]/[AOT]) has been investigated by FT-IR spectroscopy and time domain reflectometry. The study emphasises how the progressive hydration of the surfactant head groups is mainly responsible for the structural and dynamical evolution of water/AOT liquid crystals. In particular, it has been found that the state of water at lower R values is strongly perturbed, bulk-like water appears only at R>23 and the water/AOT interface polarisation is controlled by the fast translational dynamics of sodium counterions and the slow orientational dynamics of the AOT ionic head groups.

  2. Estimation of aerosol type from airborne hyperspectral data: a new technique designed for industrial plume characterization

    NASA Astrophysics Data System (ADS)

    Deschamps, A.; Marion, R.; Foucher, P.-Y.; Briottet, X.

    2012-11-01

    The determination of the aerosol type in a plume from remotely sensed data without any a priori knowledge is a challenging task. If several methods have already been developed to characterize the aerosols from multi or hyperspectral data, they are not suited for industrial particles, which have specific physical and optical properties, changing quickly and in a complex way with the distance from the source emission. From radiative transfer equations, we have developed an algorithm, based on a Look-Up Table approach, enabling the determination of the type of this kind of particles from hyperspectral data. It consists in the selection of pixels pairs, located at the transitions between two kinds of grounds (or between an illuminated and a shadow area), then in the comparison between normalized estimated Aerosol Optical Thicknesses (AOTs) and pre-calculated AOTs. The application of this algorithm to simulated data leads to encouraging results: the selection of only six pixels pairs allows the algorithm to differentiate aerosols emitted by a metallurgical plant from biomass burning particles, urban aerosols and particles from an oil depot explosion, regardless the size and the aerosol concentration. The algorithm performances are better for a relatively high AOT but the single scattering approximation does not enable the characterization of thick plumes (AOT above 2.0). However, the choice of transitions (type of grounds) does not seem to significantly affect the results.

  3. Synthesis and characterization of silver nanoparticles in AOT microemulsion system

    NASA Astrophysics Data System (ADS)

    Zhang, Wanzhong; Qiao, Xueliang; Chen, Jianguo

    2006-11-01

    Colloidal silver nanoparticles have been synthesized in water-in-oil microemulsion using silver nitrate solubilized in the water core of one microemulsion as source of silver ions, hydrazine hydrate solubilized in the water core of another microemulsion as reducing agent, dodecane as the oil phase, sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as the surfactant. The UV-vis absorption spectra and transmission electron microscopy (TEM) have been used to trace the growth process and elucidate the structure of the silver nanoparticles. UV-vis spectra show that the Ag4+ intermediates formed at early stages of the reaction and then the clusters grow or aggregate to larger nanoparticles. TEM micrographs confirm that the silver nanoparticles are all spherical. The resulting particles have a very narrow size distribution. Meanwhile, the diameter size of the particles is so small that the smallest mean diameter is only 1.6 nm. IR results show that the surfactant molecules are strongly adsorbed on the surface of silver particles through a coordination bond between the silver atom and the sulfonic group of AOT molecules, which endows the particles with a good stability in oil solvents. As dodecane is used as oil solvent to prepare silver nanoparticles, the formed nano-silver sol is almost nontoxic. As a result, the silver nanoparticles need not be separated from the reaction solution and the silver sol may be directly used in antibacterial fields.

  4. Distribution of Aerosol During Diwali Festival in the Recent Decade over India

    NASA Astrophysics Data System (ADS)

    Gouda, K. C.; Bhat, N.; Goswami, P.

    2012-12-01

    Diwali is a very famous festival in India during which people play with crackers and fireworks. Due to burning of crackers and fireworks, the concentration of anthropogenic aerosol increases in the atmosphere. In the present work the temporal and spatial variation of atmospheric aerosol parameters like Aerosol Optical Thickness (AOT), Aerosol Depth (AOD), TWC, Aerosol Particle size etc. are analyzed using the high resolution satellite data from different sources. 10 year Climatology of the Aerosol over India is generated using the data before, after and during Diwali festival time for the period of 2002 to 2011. The three climatologies show different distribution of the aerosol parameters through out the country. The northern and eastern part shows more rich in the aerosol during the festival. To understand the temporal variability, analysis of aerosol properties are being carried out one week before the festival day and one week after the festival day and compared with the day of festival for all the years. It is observed that the AOD increases from the preceding days of the festival since people start playing with crackers and fireworks about two days prior to the main Diwali day especially in North India. It is also observed from the present study that during the Diwali month the aerosol parameters are maximum in Northern part of India which supports the practice of higher incidences of bio-mass burning and residues of waste agricultural crop's fire activities. Ten year (2002-2011) average distribution of MODIS derived Aerosol Optical Thickness (AOT) during Diwali over India is presented in figure 1. A complete evaluation of distribution of AOT, AOD, TWC, Rainfall, suspended particulate Material etc. along with statistical analysis are also presented in this work. Figure 1: Ten year (2002-2011) average distribution of MODIS derived Aerosol Optical Thickness (AOT) during Diwali over India

  5. LASE measurements of aerosols and water vapor during TARFOX

    NASA Technical Reports Server (NTRS)

    Ferrare, Richard A.; Ismail, Syed; Browell, Edward V.; Brackett, Vincent G.; Kooi, Susan A.; Clayton, Marian B.; Melfi, Harvey; Whiteman, David N.; Schwenner, Geary; Evans, Keith D.; Hobbs, Peter V.; Veefkind, J. Pepijn; Russell, Philip B.; Livingston, John M.; Hignett, Philip; Holben, Brent N.; Remer, Lorraine A.

    1998-01-01

    The TARFOX (Tropospheric Aerosol Radiative Forcing Observational Experiment) intensive field campaign was designed to reduce uncertainties in estimates of the effects of anthropogenic aerosols on climate by measuring direct radiative effects and the optical, physical, and chemical properties of aerosols [1]. TARFOX was conducted off the East Coast of the United States between July 10-31, 1996. Ground, aircraft, and satellite-based sensors measured the sensitivity of radiative fields at various atmospheric levels to aerosol optical properties (i.e., optical thickness, phase function, single-scattering albedo) and to the vertical profile of aerosols. The LASE (Lidar Atmospheric Sensing Experiment) instrument, which was flown on the NASA ER-2 aircraft, measured vertical profiles of total scattering ratio and water vapor during a series of 9 flights. These profiles were used in real-time to help direct the other aircraft to the appropriate altitudes for intensive sampling of aerosol layers. We have subsequently used the LASE aerosol data to derive aerosol backscattering and extinction profiles. Using these aerosol extinction profiles, we derived estimates of aerosol optical thickness (AOT) and compared these with measurements of AOT from both ground and airborne sun photometers and derived from the ATSR-2 (Along Track and Scanning Radiometer 2) sensor on ERS-2 (European Remote Sensing Satellite-2). We also used the water vapor mixing ratio profiles measured simultaneously by LASE to derive precipitable water vapor and compare these to ground based measurements.

  6. The Retrieval of Aerosol Optical Thickness Using the MERIS Instrument

    NASA Astrophysics Data System (ADS)

    Mei, L.; Rozanov, V. V.; Vountas, M.; Burrows, J. P.; Levy, R. C.; Lotz, W.

    2015-12-01

    Retrieval of aerosol properties for satellite instruments without shortwave-IR spectral information, multi-viewing, polarization and/or high-temporal observation ability is a challenging problem for spaceborne aerosol remote sensing. However, space based instruments like the MEdium Resolution Imaging Spectrometer (MERIS) and the successor, Ocean and Land Colour Instrument (OLCI) with high calibration accuracy and high spatial resolution provide unique abilities for obtaining valuable aerosol information for a better understanding of the impact of aerosols on climate, which is still one of the largest uncertainties of global climate change evaluation. In this study, a new Aerosol Optical Thickness (AOT) retrieval algorithm (XBAER: eXtensible Bremen AErosol Retrieval) is presented. XBAER utilizes the global surface spectral library database for the determination of surface properties while the MODIS collection 6 aerosol type treatment is adapted for the aerosol type selection. In order to take the surface Bidirectional Reflectance Distribution Function (BRDF) effect into account for the MERIS reduce resolution (1km) retrieval, a modified Ross-Li mode is used. The AOT is determined in the algorithm using lookup tables including polarization created using Radiative Transfer Model SCIATRAN3.4, by minimizing the difference between atmospheric corrected surface reflectance with given AOT and the surface reflectance calculated from the spectral library. The global comparison with operational MODIS C6 product, Multi-angle Imaging SpectroRadiometer (MISR) product, Advanced Along-Track Scanning Radiometer (AATSR) aerosol product and the validation using AErosol RObotic NETwork (AERONET) show promising results. The current XBAER algorithm is only valid for aerosol remote sensing over land and a similar method will be extended to ocean later.

  7. Aerosol Optical Thickness comparisons between NASA LaRC Airborne HSRL and AERONET during the DISCOVER-AQ field campaigns

    NASA Astrophysics Data System (ADS)

    Scarino, A. J.; Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Berkoff, T.; Cook, A. L.; Harper, D. B.; Hoff, R. M.; Holben, B. N.; Schafer, J.; McGill, M. J.; Yorks, J. E.; Lantz, K. O.; Michalsky, J. J.; Hodges, G.

    2013-12-01

    The first- and second-generation NASA airborne High Spectral Resolution Lidars (HSRL-1 and HSRL-2) have been deployed on board the NASA Langley Research Center King Air aircraft during the Deriving Information on Surface Conditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaigns. These included deployments during July 2011 over Washington, D.C. and Baltimore, MD and during January and February 2013 over the San Joaquin Valley (SJV) of California and also a scheduled deployment during September 2013 over Houston, TX. Measurements of aerosol extinction, backscatter, and depolarization are available from both HSRL-1 and HSRL-2 in coordination with other participating research aircraft and ground sites. These measurements constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, aerosol optical thickness (AOT), as well as the Mixing Layer Height (MLH). HSRL AOT is compared to AOT measured by the Distributed Regional Aerosol Gridded Observation Networks (DRAGON) and long-term AERONET sites. For the 2011 campaign, comparisons of AOT at 532nm between HSRL-1 and AERONET showed excellent agreement (r = 0.98, slope = 1.01, intercept = 0.037) when the King Air flights were within 2.5 km of the ground site and 10 min from the retrieval time. The comparison results are similar for the 2013 DISCOVER-AQ campaign in the SJV. Additional ground-based (MPL) and airborne (CPL) lidar data were used to help screen for clouds in the AERONET observations during the SJV portion. AOT values from a Multi-Filter Rotating Shadowband Radiometer (MFRSR) located at the Porterville, CA site during the SJV campaign are also compared to HSRL-2 AOT. Lastly, using the MLH retrieved from HSRL aerosol backscatter profiles, we describe the distribution of AOT relative to the MLH.

  8. Using Airborne High Spectral Resolution Lidar Data to Evaluate Combined Active Plus Passive Retrievals of Aerosol Extinction Profiles

    NASA Technical Reports Server (NTRS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Kittaka, C.; Vaughn, M. A.; Remer, L. A.

    2010-01-01

    We derive aerosol extinction profiles from airborne and space-based lidar backscatter signals by constraining the retrieval with column aerosol optical thickness (AOT), with no need to rely on assumptions about aerosol type or lidar ratio. The backscatter data were acquired by the NASA Langley Research Center airborne High Spectral Resolution Lidar (HSRL) and by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) instrument on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. The HSRL also simultaneously measures aerosol extinction coefficients independently using the high spectral resolution lidar technique, thereby providing an ideal data set for evaluating the retrieval. We retrieve aerosol extinction profiles from both HSRL and CALIOP attenuated backscatter data constrained with HSRL, Moderate-Resolution Imaging Spectroradiometer (MODIS), and Multiangle Imaging Spectroradiometer column AOT. The resulting profiles are compared with the aerosol extinction measured by HSRL. Retrievals are limited to cases where the column aerosol thickness is greater than 0.2 over land and 0.15 over water. In the case of large AOT, the results using the Aqua MODIS constraint over water are poorer than Aqua MODIS over land or Terra MODIS. The poorer results relate to an apparent bias in Aqua MODIS AOT over water observed in August 2007. This apparent bias is still under investigation. Finally, aerosol extinction coefficients are derived from CALIPSO backscatter data using AOT from Aqua MODIS for 28 profiles over land and 9 over water. They agree with coincident measurements by the airborne HSRL to within +/-0.016/km +/- 20% for at least two-thirds of land points and within +/-0.028/km +/- 20% for at least two-thirds of ocean points.

  9. MASTER discoveries: dwarf novae, PSN, OT in Andromeda direction

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Gress, O.; Balanutsa, P.; Lipunov, V.; Rebolo Lopez, R.; Serra Ricart, M.; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Kornilov, V.; Ivanov, K.

    2016-09-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 00h 41m 26.22s +41d 43m 50.0s on 2016-09-02.12339 UT. The OT unfiltered magnitude is 19.7m, mlim=20.0 The OT is seen in 14 images.

  10. MASTER-Kislovodsk: bright OT with 7mag amplitude

    NASA Astrophysics Data System (ADS)

    Gress, O.; Lipunov, V.; Gorbovskoy, E.; Samus, N.; Tiurina, N.; Balanutsa, P.; Vladimirov, V.; Kuznetsov, A.; Kornilov, V.; Shumkov, V.; Gorbunov, I.; Vlasenko, D.; Kuvshinov, D.; Tlatov, A.; Senik, V.; Dormidontov, D.; Parkhomenko, A.

    2016-02-01

    MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010 )discovered OT source at (RA, Dec) = 07h 33m 25.52s +37d 37m 44.9s on 2016-02-24.90468 UT. The OT unfiltered magnitude is 15.1m (limit 18.0m).The OT is seen in 3 images.

  11. EPR study of polyaniline synthesized enzymatically in the presence of submicrometer-sized AOT vesicles.

    PubMed

    Rakvin, Boris; Carić, Dejana; Andreis, Mladen; Junker, Katja; Walde, Peter

    2014-02-27

    EPR spectroscopy was used to examine the magnetic properties of two enzymatically synthesized polyaniline (PANI) samples obtained in the presence of submicrometer-sized vesicles formed from sodium bis(2-ethylhexyl)sulfosuccinate (AOT) as templates. PANI-HRPC-AOT was synthesized with horseradish peroxidase isoenzyme C (HRPC) and hydrogen peroxide (H2O2) as oxidant while PANI-TvL-AOT was prepared with Trametes versicolor laccase (TvL) and dioxygen (O2) as oxidant. A commercial conductive sample of the emeraldine salt form of polyaniline (PANI-ES) was also used for comparison in order to correlate the experimental data obtained for PANI-HRPC-AOT and PANI-TvL-AOT with the properties of the well-characterized PANI-ES. It was shown that a model based on the concept of correlated polaronic bands could be applied for the interpretation of the EPR spectra of all three examined samples, although PANI-HRPC-AOT and PANI-TvL-AOT were significantly less conductive than PANI-ES. The magnetic properties of the PANI samples could be related to their conductivities, whereby a low conductivity was ascribed to decreased interchain spin interactions which were detectable from a splitting of the triplet spectrum at low temperatures (5-10 K). The obtained effective distance between the polyaniline chains is larger for enzymatically synthesized PANI than for PANI-ES, most likely mainly due to the presence of AOT which could not be removed completely during the work-up. AOT influences the chain conformation and the average chain-chain distance. PMID:24484357

  12. Comparison of Aerosol Optical Properties and Water Vapor Among Ground and Airborne Lidars and Sun Photometers During TARFOX

    NASA Technical Reports Server (NTRS)

    Ferrare, R.; Ismail, S.; Browell, E.; Brackett, V.; Clayton, M.; Kooi, S.; Melfi, S. H.; Whiteman, D.; Schwemmer, G.; Evans, K.

    2000-01-01

    We compare aerosol optical thickness (AOT) and precipitable water vapor (PWV) measurements derived from ground and airborne lidars and sun photometers during the Tropospheric Aerosol Radiative Forcing Observational Experiment. Such comparisons are important to verify the consistency between various remote sensing measurements before employing them in any assessment of the impact of aerosols on the global radiation balance. Total scattering ratio and extinction profiles measured by the ground-based NASA Goddard Space Flight Center scanning Raman lidar system, which operated from Wallops Island, Virginia (37.86 deg N, 75.51 deg W); are compared with those measured by the Lidar Atmospheric Sensing Experiment (LASE) airborne lidar system aboard the NASA ER-2 aircraft. Bias and root-mean-square differences indicate that these measurements generally agreed within about 10%. Aerosol extinction profiles and estimates of AOT are derived from both lidar measurements using a value for the aerosol extinction/backscattering ratio S(sub a) = 60 sr for the aerosol extinction/backscattering ratio, which was determined from the Raman lidar measurements. The lidar measurements of AOT are found to be generally within 25% of the AOT measured by the NASA Ames Airborne Tracking Sun Photometer (AATS-6). However, during certain periods the lidar and Sun photometer measurements of AOT differed significantly, possibly because of variations in the aerosol physical characteristics (e.g., size, composition) which affect S(sub a). Estimates of PWV, derived from water vapor mixing ratio profiles measured by LASE, are within 5-10% of PWV derived from the airborne Sun photometer. Aerosol extinction profiles measured by both lidars show that aerosols were generally concentrated in the lowest 2-3 km.

  13. Relationship between aerosol characteristics and altitude based on multi-measurements and model simulations

    NASA Astrophysics Data System (ADS)

    Nakata, Makiko; Ohshima, Tsubasa; Fujito, Toshiyuki; Sano, Itaru; Mukai, Sonoyo

    2010-10-01

    The suspending particulate matter (PM2.5) is a typical indicator of small particles in the atmosphere. Accordingly in order to monitor the air quality, sampling of PM2.5 has been widely undertaken over the world, especially in the urban cities. On the other hand, it is known that the sun photometry provides us with the aerosol information, e.g. aerosol optical thickness (AOT), aerosol size information and so on. Simultaneous measurements of PM2.5 and the AOT have been performed at a NASA/AERONET (Aerosol Robotics Network) site in urban city of Higashi-Osaka in Japan since March 2004, and successfully provided a linear correlation between PM2.5 and AOT in separately considering with several cases, e.g. usual, anthropogenic aerosols, dust aerosols and so on. This fact suggests that the vertical distribution also should be taken into account separately for each aerosol type. In this work, vertical profiles of atmospheric aerosols are considered based on combination use of photometric data with AERONET, LIDAR (Light Detection and Ranging) measurements and model simulations.

  14. Gas phase charged aggregates of bis(2-ethylhexyl)sulfosuccinate (AOT) and divalent metal ions: first evidence of AOT solvated aggregates.

    PubMed

    Giorgi, Gianluca; Pini, Ivana; Ceraulo, Leopoldo; Liveri, Vincenzo Turco

    2011-09-01

    Assembling and chelating properties of sodium bis(2-ethylhexyl)sulfosuccinate (AOTNa) towards divalent metal ions have been investigated in the gas phase by electrospray ionization mass spectrometry. A variety of positively charged monometallated and mixed metal aggregates are formed. Interestingly, several ions contain solvent (MeOH, H(2)O) molecules and constitute the most abundant AOT cationic aggregates not containing sodium. These species are the first example of solvated AOT-metal ion aggregates in the gas phase. By increasing the surfactant aggregation number, the abundance of solvated species becomes lower than that of unsolvated ones. Decompositions of ionic species have been studied by tandem mass spectrometry, and their stability has been determined through energy resolved mass spectrometry. In contrast with positively charged AOT-alkaline metal ion aggregates, whose decompositions are dominated by the loss of individual surfactant molecules, AOTNa-divalent ion aggregates mainly dissociate through the cleavage of the AOT H(2)C-O bond followed by further intramolecular fragmentations. This finding, that is consistent with an enhanced chelation of divalent ions with AOT(-) head groups, has been taken as an indication that such aggregates are characterized by a reverse micelle-like organization with a ionic core formed by the metal cations interacting with the negatively charged surfactant polar heads, whereas the surfactant alkyl chains point outside. PMID:21915957

  15. Aerosol Properties From Multi-angle Satellite Imaging

    NASA Astrophysics Data System (ADS)

    Kahn, R. A.; Martonchik, J. V.; Diner, D. J.; Chen, W. A.; Gaitley, B. J.; Kalashnikova, O. V.; Liu, Y.; Team, T.

    2005-12-01

    Based on pre-launch simulations, we expected that data from the multi-angle, multi-spectral MISR instrument aboard NASA's Terra satellite would contain, in addition to aerosol optical depth (AOT), information about particle size, shape, and single-scattering albedo (SSA). Such information would add a great deal to the global aerosol picture that satellites provide, allowing more meaningful assessments of aerosol direct radiative impact, source attribution, material fluxes, and possibly indirect effects of aerosols on clouds. But particle micro-physical property retrievals are much more difficult to validate than AOT, since there are significant uncertainties in aerosol size, and especially shape and SSA, retrieved from surface-based sun photometers, whereas instrumented aircraft must fly complex patterns to adequately sample all aerosol layers in the entire column seen simultaneously by MISR. Our multi-faceted validation effort, which makes use of ground-based AERONET sun photometers as well as coincident satellite and intensive field observations, has allowed us to quantify MISR data sensitivity to these aerosol micro-physical properties over dark water, and in a few situations, over land. In broad terms, over dark water MISR can distinguish three-to-five aerosol size bins between about 0.1 and 2.5 microns effective diameter, spherical vs. non-spherical particle shapes, plates from grains from spheroids at least in some cases, and two-to-four SSA groupings between 0.75 and 1.0. MISR can also identify several aerosol modes within the column, provided each contributes more than about 20% to the total column mid-visible AOT. These sensitivities diminish for column AOT below about 0.15, and for brighter underlying surfaces. This talk will summarize the current status of the MISR Standard Aerosol Product, the latest MISR Research Aerosol Retrieval validation study results, and our plans for completing aerosol micro-physical property formal validation for the MISR

  16. An online aerosol retrieval algorithm using OMI near-UV observations based on the optimal estimation method

    NASA Astrophysics Data System (ADS)

    Jeong, U.; Kim, J.; Ahn, C.; Torres, O.; Liu, X.; Bhartia, P. K.; Spurr, R. J. D.; Haffner, D.; Chance, K.; Holben, B. N.

    2015-06-01

    An online version of the OMI (Ozone Monitoring Instrument) near-ultraviolet (UV) aerosol retrieval algorithm was developed to retrieve aerosol optical thickness (AOT) and single scattering albedo (SSA) based on the optimal estimation (OE) method. Instead of using the traditional look-up tables for radiative transfer calculations, it performs online radiative transfer calculations with the Vector Linearized Discrete Ordinate Radiative Transfer (VLIDORT) model to eliminate interpolation errors and improve stability. The OE-based algorithm has the merit of providing useful estimates of uncertainties simultaneously with the inversion products. The measurements and inversion products of the Distributed Regional Aerosol Gridded Observation Network campaign in Northeast Asia (DRAGON NE-Asia 2012) were used to validate the retrieved AOT and SSA. The retrieved AOT and SSA at 388 nm have a correlation with the Aerosol Robotic Network (AERONET) products that is comparable to or better than the correlation with the operational product during the campaign. The estimated retrieval noise and smoothing error perform well in representing the envelope curve of actual biases of AOT at 388 nm between the retrieved AOT and AERONET measurements. The forward model parameter errors were analyzed separately for both AOT and SSA retrievals. The surface albedo at 388 nm, the imaginary part of the refractive index at 354 nm, and the number fine mode fraction (FMF) were found to be the most important parameters affecting the retrieval accuracy of AOT, while FMF was the most important parameter for the SSA retrieval. The additional information provided with the retrievals, including the estimated error and degrees of freedom, is expected to be valuable for future studies.

  17. Dust aerosol and optical properties over North Africa simulated with the ALADIN numerical prediction model from 2006 to 2010

    NASA Astrophysics Data System (ADS)

    Mokhtari, M.; Tulet, P.; Fischer, C.; Bouteloup, Y.; Bouyssel, F.; Brachemi, O.

    2015-02-01

    The seasonal cycle and optical properties of mineral dust aerosols in North Africa were simulated for the period from 2006 to 2010 using the numerical atmospheric model ALADIN coupled to the surface scheme SURFEX. The particularity of the simulations is that the major physical processes responsible for dust emission and transport, as well as radiative effects, are taken into account at short timescales and mesoscale resolution. The aim of these simulations is to quantify the dust emission and deposition, locate the major areas of dust emission and establish a climatology of aerosol optical properties in North Africa. The mean monthly Aerosol Optical Thickness (AOT) simulated by ALADIN is compared with the AOTs derived from the standard Dark Target (DT) and Deep Blue (DB) algorithms of the Aqua-MODIS (MODerate resolution Imaging Spectroradiometer) products over North Africa, and with a set of sun photometer measurements located at Banizoumbou, Cinzana, Soroa, Mbour and Capo Verde. The vertical distribution of dust aerosol represented by extinction profiles is also analysed using CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations. The annual dust emission simulated by ALADIN over North Africa is 878 Tg year-1. The Bodélé depression appears to be the main area of dust emission in North Africa, with an average estimate of about 21.6 Tg year-1. The simulated AOTs are in good agreement with satellite and sun photometer observations. The positions of the maxima of the modelled AOTs over North Africa match the observed positions, and the ALADIN simulations satisfactorily reproduce the various dust events over the 2006-2010 period. The AOT climatology proposed in this paper provides a solid database of optical properties and consolidates the existing climatology over this region derived from satellites, the AERONET network and Regional Climate Models. Moreover, the three-dimensional distribution of the simulated AOTs also provides information about the

  18. Intercomparison between satellite-derived aerosol optical thickness and PM2.5 mass: Implications for air quality studies

    NASA Astrophysics Data System (ADS)

    Wang, Jun; Christopher, Sundar A.

    2003-11-01

    We explore the relationship between column aerosol optical thickness (AOT) derived from the Moderate Resolution Imaging SpectroRadiometer (MODIS) on the Terra/Aqua satellites and hourly fine particulate mass (PM2.5) measured at the surface at seven locations in Jefferson county, Alabama for 2002. Results indicate that there is a good correlation between the satellite-derived AOT and PM2.5 (linear correlation coefficient, R = 0.7) indicating that most of the aerosols are in the well-mixed lower boundary layer during the satellite overpass times. There is excellent agreement between the monthly mean PM2.5 and MODIS AOT (R > 0.9), with maximum values during the summer months due to enhanced photolysis. The PM2.5 has a distinct diurnal signature with maxima in the early morning (6:00 ~ 8:00AM) due to increased traffic flow and restricted mixing depths during these hours. Using simple empirical linear relationships derived between the MODIS AOT and 24hr mean PM2.5 we show that the MODIS AOT can be used quantitatively to estimate air quality categories as defined by the U.S. Environmental Protection Agency (EPA) with an accuracy of more than 90% in cloud-free conditions. We discuss the factors that affect the correlation between satellite-derived AOT and PM2.5 mass, and emphasize that more research is needed before applying these methods and results over other areas.

  19. An Improved Method for Estimating Aerosol Optical Thickness from Artificial Light Sources Observed by the Visible/Infrared Imaging Radiometer Suite Day/Night Band

    NASA Astrophysics Data System (ADS)

    McHardy, Theodore Mitchell

    Using Visible/Infrared Imaging Radiometer Suite (VIIRS) Day/Night Band (DNB) data, a method, dubbed the "variance method", is developed for retrieving nighttime aerosol optical thickness (AOT) values based on the dispersion of radiance values above an artificial light source. An improvement of a previous algorithm, this updated method derives a semi-quantitative indicator of nighttime AOT using artificial light sources. Nighttime AOT retrievals from the newly developed method are inter-compared with an interpolated value from late afternoon and early morning ground observations from four AErosol RObotic NETwork (AERONET) sites as well as column-integrated Aerosol Optical Depth (AOD) from one High Spectral Resolution LiDAR (HSRL) site at Huntsville, AL during the NASA Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) campaign, providing full diel coverage. This method does not account for lunar reflectance from either the surface or the aerosol layer. Sensitivity tests do no indicate large systematic or random errors associated with lunar illumination. VIIRS AOT retrievals yield a coefficient of determination (r2) of 0.60 and a root-mean-squared-error (RMSE) of 0.18 when compared against straddling daytime-averaged AERONET AOT values. Preliminary results suggest that artificial light sources can be used for estimating regional and global nighttime aerosol distributions in the future.

  20. Aerosol Optical Thickness in the Presence and Absence of African Dust using AERONET and Microtops II Sunphotometers

    NASA Astrophysics Data System (ADS)

    Ruiz, A.; Raizada, S.; Tepley, C. A.; Venero, I.; Zurcher, F.; Mayol-Bracero, O. L.

    2011-12-01

    As part of the Puerto Rico African Dust and Cloud Study (PRADACS) Project, we present a comparison of the aerosol optical thickness (AOT) between the AERONET sunphotometer (CIMEL Electronique 318A) located at Cape San Juan (CSJ, 18° 23' N, 65° 37' E), Puerto Rico, and the radiometers (Microtops II) of the Arecibo Observatory. Data were collected at CSJ during the summer period of 2011, when African dust was present most of the time. Preliminary results showed, for both instruments, AOT values around of 0.4 when there were high concentrations of African dust over the island Puerto Rico. The AOT correlations between the two instruments were very good, with a slope of 0.8 and r2 of 0.9 for all wavelengths. The main differences observed were on the values above 0.6. We will show the temporal behavior of AOT for the two instruments and the spatial differences between them.

  1. FTIR spectroscopic study of the acrylamide states in AOT reversed micelles

    NASA Astrophysics Data System (ADS)

    Guo, Yilu; Wu, Peiyi

    2008-07-01

    The state of acrylamide (AM) confined within the hydrophilic core of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reversed micelles has been investigated by Fourier transform infrared spectroscopy with an attenuated total reflection (ATR) accessory. 2D correlation spectroscopy and curve fitting revealed that the acrylamide molecule was carried into the micellar core by one of the two long tails of the AOT through H-bonding between the amide group and the carbonyl group of AOT. The acrylamide tended to stick at the interface of the inverse emulsion at lower acrylamide-to-AOT molar ratio value ( X); when X increased to some higher values, the acrylamide would tend to congregate in the micellar core. Therefore, it is important to choose the suitable initiator for the inverse emulsion polymerization under different experimental conditions.

  2. Enthalpies of solution and volumes of water in reversed AOT micelles

    SciTech Connect

    D'Aprano, A.; Lizzio, A.; Liveri, V.T.

    1987-08-27

    Molar enthalpies of solution and apparent molar volumes of water in the sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/n-heptane system as a function of the molar ratio R = (water)/(AOT) were determined at 25 /sup 0/C. The dependence of these experimental data on R has been rationalized in terms of a semiempirical model based on water partitioning between two states. The positive enthalpies of solution of water indicate that the insertion of water in reversed AOT micelles (unfavorable from an enthalpic point of view) is mainly driven by a favorable change on entropy. An increase of the maximum number of water molecules solvating AOT with increasing concentration of surfactant has also been observed and discussed.

  3. MASTER-IAC: PSN in PGC1671957 and bright OT

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Lipunov, V.; Rebolo Lopez, R.; Serra Ricart, M.; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Kornilov, V.; Gress, O.; Ivanov, K.; Shumkov, V.

    2016-09-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 23h 36m 08.12s +22d 32m 33.1s on 2016-09-07.05299 UT. The OT unfiltered magnitude is 17.8m (limit 20.1m).

  4. MASTER-IAC: bright QSO flare and OT discovery

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Popova, E.; Gress, O.; Lipunov, V.; Lopez, R. Rebolo; Serra-Ricart, M.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kornilov, V.; Kuznetsov, A.; Kuvshinov, D.; Vlasenko, D.; Chazov, V.; Israelyan, G.; Lodieu, N.; Budnev, N.; Ivanov, K.; Shurpakov, S.

    2016-07-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L )discovered OT source at (RA, Dec) = 19h 18m 40.69s +42d 21m 03.3s on 2016-07-25.00863 UT. The OT magnitude in unfiltered is 17.9m (limit 18.7m).

  5. MASTER-IAC: very bright high amplitude OT

    NASA Astrophysics Data System (ADS)

    Gress, O.; Lipunov, V.; Lopez, R. Rebolo; Serra-Ricart, M.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kornilov, V.; Kuznetsov, A.; Kuvshinov, D.; Vlasenko, D.; Vladimirov, V.; Popova, E.; Chazov, V.; Israelyan, G.; Lodieu, N.; Budnev, N.; Ivanov, K.

    2016-07-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 20h 48m 06.68s +13d 54m 23.3s on 2016-07-24.16661 UT. The OT unfiltered magnitude is (limit 18.5m).

  6. MASTER: very bright OT in Large Magellanic cloud direction

    NASA Astrophysics Data System (ADS)

    Gorbovskoy, E.; Lipunov, V.; Buckley, D.; Tiurina, N.; Balanutsa, P.; Kornilov, V.; Gorbunov, I.; Kuznetsov, A.; Gress, O.; Vladimirov, V.; Popova, E.; Vlasenko, D.; Kuvshinov, D.; Potter, S.

    2016-05-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 05h 10m 32.58s -69d 21m 30.4s on 2016-05-10.72797 UT. The OT unfiltered magnitude is (limit 17.6m).

  7. MASTER: PSN in PGC032587 and new OTs

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Popova, E.; Lipunov, V.; Lopez, R. Rebolo; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Gorbunov, I.; Chazov, V.; Gress, O.; Ivanov, K.; Vladimirov, V.; Vlasenko, D.; Kuvshinov, D.; Serra-Ricart, M.; Israelyan, G.; Potter, S.; Kniazev, A.

    2016-06-01

    MASTER-IAC auto-detection system Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 discovered OT source at (RA, Dec) = 10h 51m 45.85s +55d 23m 12.4s on 2016-05-31.97997 UT. The OT unfiltered magnitude is 18.3 (limit 20.1m).

  8. Master-Iac Master-Saao 2 bright OTs

    NASA Astrophysics Data System (ADS)

    Gress, O.; Pogrosheva, T.; Lipunov, V.; Lopez, R. Rebolo; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Gorbunov, I.; Kuznetsov, A.; Popova, E.; Kuvshinov, D.; Serra-Ricart, M.; Israelian, G.; Potter, S.; Kniazev, A.

    2016-05-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 00h 10m 21.33s +73d 15m 16.5s on 2016-05-24.18141 UT. The OT unfiltered magnitude is 15.7m (limit 18.1m).

  9. MASTER-Net discoveries: PSN, new Blazar and OT

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Balanutsa, P.; Popova, E.; Lipunov, V.; Buckley, D.; Lopez, R. Rebolo; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Kornilov, V.; Vlasenko, D.; Gorbunov, I.; Gress, O.; Vladimirov, V.; Kuvshinov, D.; Ricart, M. Serra; Israelyan, G.; Potter, S.; Kniazev, A.

    2016-03-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 13h 57m 48.95s -27d 26m 23.4s on 2016-03-30.02359 UT. The OT unfiltered magnitude is 17.7m (limit 19.8m).

  10. Very Bright OT detected by MASTER-SAAO

    NASA Astrophysics Data System (ADS)

    Gress, O.; Lipunov, V.; Gorbovskoy, E.; Buckley, D.; Budnev, N.; Tiurina, N.; Balanutsa, P.; Kornilov, V.; Kuznetsov, A.; Shumkov, V.; Gorbunov, I.; Vlasenko, D.; Vladimirov, V.; Popova, E.; Potter, S.; Kotze, M.

    2016-01-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 00h 38m 31.10s -64d 03m 13.7s on 2016-01-26.85306 UT. The OT unfiltered magnitude is 12.7m (limit 18.5m).

  11. 12 CFR 500.10 - The OTS or The Office.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 6 2014-01-01 2012-01-01 true The OTS or The Office. 500.10 Section 500.10 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY AGENCY ORGANIZATION AND FUNCTIONS General Organization § 500.10 The OTS or The Office. The Office of Thrift Supervision (referred...

  12. Statistical variability of top of atmosphere cloud-free shortwave aerosol radiative effect

    NASA Astrophysics Data System (ADS)

    Jones, T. A.; Christopher, S. A.

    2007-06-01

    The statistical variability of globally averaged MODIS aerosol optical thickness at 0.55 μm (AOT) and top of atmosphere CERES cloud-free shortwave radiative effect (SWRE) is presented. Statistical variability is defined as the robustness of globally averaged statistics relative to data distribution. At the CERES footprint level, which we label "raw data", both the AOT and SWRE data derived from clear-sky CERES-SSF products show significant deviations from a normal distribution as evidenced by high skewness values. The spatial and temporal distribution of the data is also not uniform, with a greater concentration of data occurring in aerosol heavy-regions. As a result, globally averaged AOT and SWRE are overestimated when derived from raw data alone. To compensate, raw data are gridded into 2×2 degree grid-cells (called "gridded" data) to reduce the effect of spatial non-uniformity. However, the underlying non-normal distribution remains and manifests itself by increasing the uncertainty of grid-cell values. Globally averaged AOT and SWRE derived from a gridded dataset are substantially lower than those derived from raw data alone. The range of globally averaged AOT and SWRE values suggests that up to a 50% statistical variability exists, much of which is directly tied to how the data are manipulated prior to averaging. This variability increases when analyzing aerosol components (e.g. anthropogenic) since component AOT (and SWRE) may not exist at all locations were AOT is present. As a result, regions where a particular component AOT does not exist must either not be included in the global average or have data within these regions set to null values. However, each method produces significantly different results. The results of this work indicate simple mean and standard deviation statistics do not adequately describe global aerosol climate forcing data sets like the one used here. We demonstrate that placing raw observations on to a uniform grid is a necessary

  13. Smoke aerosol and its radiative effects during extreme fire event over Central Russia in summer 2010

    NASA Astrophysics Data System (ADS)

    Chubarova, N.; Nezval', Y.; Sviridenkov, M.; Smirnov, A.; Slutsker, I.

    2011-10-01

    Different microphysical, optical and radiative properties of aerosol were analyzed during the severe fires in summer 2010 over Central Russia using ground measurements at two AERONET sites in Moscow and Zvenigorod (Moscow suburb) and radiative measurements in Moscow. Volume aerosol size distribution in smoke conditions was shown to have a bimodal character with the significant prevalence of fine mode aerosol particles which effective radius shifted to higher values (reff-fine = 0.24 μm against approximately 0.15 μm in typical conditions). Imaginary part of refractive index in visible region was characterized by lower values compared with typical conditions (REFI = 0.006 against REFI = 0.01) and single scattering albedo (SSA) was significantly higher (SSAλ=675nm = 0.95 against SSAλ=675nm ~ 0.9). Extremely high daily average AOT's were observed on 6-8 August reaching the absolute maximum on 7 August up to AOT500 = 6.4 in Moscow and AOT500 = 5.9 at Zvenigorod. A dramatic attenuation of solar irradiance at ground in cloudless but smoky conditions was also observed. Maximum irradiance loss has reached 64% for global shortwave irradiance, 91% for UV radiation 300-380 nm and 97% for erythemally-weighted UV irradiance even at relatively high solar elevation due to extremely high AOT and smaller SSA values in UV (0.8-0.9) compared with SSA in visible region of spectrum. The assessments of radiative forcing effect (RFE) at the TOA indicated a significant cooling of the smoky atmosphere. Instant RFE reached -167 Wm-2 at AOT500 = 6.4 while climatological RFE calculated for monthly mean AOT in August 2010 was about -65 Wm-2 compared with -20 Wm-2 for typical aerosol conditions according to the 10 year period of measurements in Moscow.

  14. New phases found in reverse micelle systems with high concentrations of AOT.

    PubMed

    Lai, Wei-Chi; Lai, Po-Hsiang

    2013-08-15

    This paper discusses the phase behavior, rheology, and structure of self-assembled sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelle systems at high AOT concentrations. When the amount of AOT and w(o) (the molar ratio of water to AOT) were changed, many different phases were found, a fact which is not discussed in the literature. Opaque gel-like phase (phase separation) occurred with high concentrations of AOT in organic solvents without water. When the AOT concentration and w(o) were increased to 18-72 m and 2, respectively, the samples were gel-like and translucent. Dynamic rheological results indicate that the viscoelastic transition agreed with a multirelaxation time model. Small-angle X-ray scattering (SAXS) results imply that these samples showed a hexagonally close-packed cylindrical structure in which the diameter of a cylinder was ~2.5-3.0 nm, depending on the water contents. Moreover, these AOT cylinders self-assembled into fiber bundles with a diameter of 1-10 μm, as determined using a polarized optical microscope. As w(o) was increased to 2-6 in 72 m AOT samples, similar rheological and SAXS results were obtained. However, a different type of viscoelastic transition occurred, from multirelaxation to single-relaxation, when w(o) was increased to 7-11. The samples were in the transparent gel-like phase, and the structures determined by SAXS were a combination of hexagonally packed cylindrical and lamellar structure. The close-packed cylindrical structures had larger radii and shorter lengths with increasing w(o). Furthermore, when w(o) was increased to 12, the gel-like phase disappeared and a highly viscous solution was observed. This is because all the cylindrical structures collapsed and transformed into lamellar structures when the amount of water was further increased. PMID:23879569

  15. Synergism of MODIS Aerosol Remote Sensing from Terra and Aqua

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Kaufman, Yoram J.; Remer, Lorraine A.

    2003-01-01

    The MODerate-resolution Imaging Spectro-radiometer (MODIS) sensors, aboard the Earth Observing System (EOS) Terra and Aqua satellites, are showing excellent competence at measuring the global distribution and properties of aerosols. Terra and Aqua were launched on December 18, 1999 and May 4, 2002 respectively, with daytime equator crossing times of approximately 10:30 am and 1:30 pm respectively. Several aerosol parameters are retrieved at 10-km spatial resolution from MODIS daytime data over land and ocean surfaces. The parameters retrieved include: aerosol optical thickness (AOT) at 0.47, 0.55 and 0.66 micron wavelengths over land, and at 0.47, 0.55, 0.66, 0.87, 1.2, 1.6, and 2.1 microns over ocean; Angstrom exponent over land and ocean; and effective radii, and the proportion of AOT contributed by the small mode aerosols over ocean. Since the beginning of its operation, the quality of Terra-MODIS aerosol products (especially AOT) have been evaluated periodically by cross-correlation with equivalent data sets acquired by ground-based (and occasionally also airborne) sunphotometers, particularly those coordinated within the framework of the AErosol Robotic NETwork (AERONET). Terra-MODIS AOT data have been found to meet or exceed pre-launch accuracy expectations, and have been applied to various studies dealing with local, regional, and global aerosol monitoring. The results of these Terra-MODIS aerosol data validation efforts and studies have been reported in several scientific papers and conferences. Although Aqua-MODIS is still young, it is already yielding formidable aerosol data products, which are also subjected to careful periodic evaluation similar to that implemented for the Terra-MODIS products. This paper presents results of validation of Aqua-MODIS aerosol products with AERONET, as well as comparative evaluation against corresponding Terra-MODIS data. In addition, we show interesting independent and synergistic applications of MODIS aerosol data from

  16. Fourier transform infrared spectroscopy of azide and cyanate ion pairs in AOT reverse micelles

    NASA Astrophysics Data System (ADS)

    Owrutsky, Jeffrey C.; Pomfret, Michael B.; Barton, David J.; Kidwell, David A.

    2008-07-01

    Evidence for ion pair formation in aqueous bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles (RMs) was obtained from infrared spectra of azide and cyanate with Li+, Na+, K+, and NH4+ counterions. The anions' antisymmetric stretching bands near 2000 cm-1 are shifted to higher frequency (blueshifted) in LiAOT and to a lesser extent in NaAOT, but they are very similar to those in bulk water with K+ and NH4+ as the counterions. The shifts are largest for low values of wo=[water]/[AOT] and approach the bulk value with increasing wo. The blueshifts are attributed to ion pairing between the anions and the counterions. This interpretation is reinforced by the similar trend (Li+>Na+>K+) for producing contact ion pairs with the metal cations in bulk dimethyl sulfoxide (DMSO) solutions. We find no evidence of ion pairs being formed in NH4AOT RMs, whereas ammonium does form ion pairs with azide and cyanate in bulk DMSO. Studies are also reported for the anions in formamide-containing AOT RMs, in which blueshifts and ion pair formation are observed more than in the aqueous RMs. Ion pairs are preferentially formed in confined RM systems, consistent with the well established ideas that RMs exhibit reduced polarity and a disrupted hydrogen bonding network compared to bulk water and that ion-specific effects are involved in mediating the structure of species at interfaces.

  17. Effect of AOT-assisted multi-walled carbon nanotubes on antibacterial activity.

    PubMed

    Bai, Yu; Park, Il Song; Lee, Sook Jeong; Wen, Pu Shan; Bae, Tae Sung; Lee, Min Ho

    2012-01-01

    The dispersing power of surfactant-modified multiwalled carbon nanotubes (MWCNTs) and their effect on the antibacterial activity were examined. The MWCNTs were modified using a dioctyl sodium sulfosuccinate (AOT) surfactant. UV-vis spectroscopy and transmission electron microscopy (TEM) were used to characterize the dispersion of MWCNTs in the aqueous phase. Fourier transform infrared spectroscopy confirmed the results of UV-vis spectroscopy and TEM, indicating that the AOT molecules had been adsorbed successfully onto the MWCNT surface. The highly dispersed AOT-modified MWCNTs showed strong antibacterial activity to Streptococcus mutans. The fluorescence images showed that the AOT-modified MWCNTs were capable of capturing bacteria and forming cell aggregates as well as killing them. The optical density growth curves and colony-forming units assays confirmed that the antibacterial activity of the AOT-modified MWCNTs was concentration-dependent and treatment time-dependent. This finding might be useful for applications of AOT-modified MWCNTs as an antibacterial agent to eliminate pathogens from a biocontaminated water phase. PMID:21958539

  18. Raman Lidar Profiling of Aerosols Over the Central US; Diurnal Variability and Comparisons with the GOCART Model

    NASA Technical Reports Server (NTRS)

    Ferrare, R. A.; Chin, M.; Clayton, M.; Turner, D.

    2002-01-01

    We use profiles of aerosol extinction, water vapor mixing ratio, and relative humidity measured by the ARM SGP Raman lidar in northern Oklahoma to show how the vertical distributions of aerosol extinction and water vapor vary throughout the diurnal cycle. While significant (20-30%) variations in aerosol extinction occurred near the surface as well as aloft, smaller (approximately 10%) variations were observed in the diurnal variability of aerosol optical thickness (AOT). The diurnal variations in aerosol extinction profiles are well correlated with corresponding variations in the average relative humidity profiles. The water vapor mixing ratio profiles and integrated water vapor amounts generally show less diurnal variability. The Raman lidar profiles are also used to evaluate the aerosol optical thickness and aerosol extinction profiles simulated by the GOCART global aerosol model. Initial comparisons show that the AOT simulated by GOCART was in closer agreement with the AOT derived from the Raman lidar and Sun photometer measurements during November 2000 than during September 2000. For both months, the vertical variability in average aerosol extinction profiles simulated by GOCART is less than the variability in the corresponding Raman lidar profiles.

  19. Application of Polarization to the MODIS Aerosol Retrieval Over Land

    NASA Technical Reports Server (NTRS)

    Levy, Robert C.; Remer, Lorraine R.; Kaufman, Yoram J.

    2004-01-01

    Reflectance measurements in the visible and infrared wavelengths, from the Moderate Resolution Imaging Spectroradiometer (MODIS), are used to derive aerosol optical thicknesses (AOT) and aerosol properties over land surfaces. The measured spectral reflectance is compared with lookup tables, containing theoretical reflectance calculated by radiative transfer (RT) code. Specifically, this RT code calculates top of the atmosphere (TOA) intensities based on a scalar treatment of radiation, neglecting the effects of polarization. In the red and near infrared (NIR) wavelengths the use of the scalar RT code is of sufficient accuracy to model TOA reflectance. However, in the blue, molecular and aerosol scattering dominate the TOA signal. Here, polarization effects can be large, and should be included in the lookup table derivation. Using a RT code that allows for both vector and scalar calculations, we examine the reflectance differences at the TOA, with and without polarization. We find that the differences in blue channel TOA reflectance (vector - scalar) may reach values of 0.01 or greater, depending on the sun/surface/sensor scattering geometry. Reflectance errors of this magnitude translate to AOT differences of 0.1, which is a very large error, especially when the actual AOT is low. As a result of this study, the next version of aerosol retrieval from MODIS over land will include polarization.

  20. Short-term Aerosol Trends: Reality or Myth?

    NASA Technical Reports Server (NTRS)

    Leptoukh, Gregory; Zubko, Viktor

    2009-01-01

    The main questions addressed in this slide presentation involve short-term trends of MODIS aerosol optical thickness (AOT) over 6 years: (1) Why are the trends different in different regions? (2) How are these trends so high? (3) Why are they "coherent" in many areas? (4) Are these changes in aerosol concentrations real, i.e., are they monotonic changes in emissions? Several views of the Spatial Distribution of AOT from Terra are shown. In conclusion there are several trends: (1) There is a broad spatial inhomogenueity in AOT trends over 6 years of MODIS Terra and Aqua (2) Some of the areas demonstrate clear positive trends related to increase of emission (e.g., Eastern China) (3) Strong trends in some other areas are superficial and might be attributed, in part, to: (3a) Least squares linear trend sensitivity to outliers (need to use more robust linear fitting method) (3b) Spatial and temporal shifts or trends in meteorological conditions, especially in wind patterns responsible for aerosol transport (6) Aerosol trends should be studied together with changes in meteorology patterns as they might closely linked together

  1. Long-term variability of aerosol optical thickness in Eastern Europe over 2001-2014 according to the measurements at the Moscow MSU MO AERONET site with additional cloud and NO2 correction

    NASA Astrophysics Data System (ADS)

    Chubarova, N. Y.; Poliukhov, A. A.; Gorlova, I. D.

    2015-07-01

    The aerosol properties of the atmosphere were obtained within the framework of the AERONET program at the Moscow State University Meteorological Observatory (Moscow MSU MO) over 2001-2014 period. The quality data control has revealed the necessity of their additional cloud and NO2 correction. The application of cloud correction according to hourly visual cloud observations provides a decrease in average aerosol optical thickness (AOT) at 500 nm of up to 0.03 compared with the standard dataset. We also show that the additional NO2 correction of the AERONET data is needed in large megalopolis, like Moscow, with 12 million residents and the NOx emission rates of about 100 kt yr-1. According to the developed method we estimated monthly mean NO2 content, which provides an additional decrease of 0.01 for AOT at 340 nm, and of about 0.015 - for AOT at 380 and 440 nm. The ratios of NO2 optical thickness to AOT at 380 and 440 nm are about 5-6 % in summer and reach 15-20 % in winter when both factors have similar effects on UV irradiance. Seasonal cycle of AOT at 500 nm is characterized by a noticeable summer and spring maxima, and minimum in winter conditions, changing from 0.08 in December and January up to 0.3 in August. The application of the additional cloud correction removes a local AOT maximum in February, and lowered the December artificial high AOT values. The pronounced negative AOT trends of about -1-5 % yr-1 have been obtained for most months, which could be attributed to the negative trends in emissions (E) of different aerosol precursors of about 116 Gg yr-2 in ESOx, 78 Gg yr-2 in ENMVOC, and 272 Gg yr-2 in ECO over European territory of Russia. No influence of natural factors on temporal AOT variations has been revealed.

  2. Validation and expected error estimation of Suomi-NPP VIIRS aerosol optical thickness and Ångström exponent with AERONET

    NASA Astrophysics Data System (ADS)

    Huang, Jingfeng; Kondragunta, Shobha; Laszlo, Istvan; Liu, Hongqing; Remer, Lorraine A.; Zhang, Hai; Superczynski, Stephen; Ciren, Pubu; Holben, Brent N.; Petrenko, Maksym

    2016-06-01

    The new-generation polar-orbiting operational environmental sensor, the Visible Infrared Imaging Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite, provides critical daily global aerosol observations. As older satellite sensors age out, the VIIRS aerosol product will become the primary observational source for global assessments of aerosol emission and transport, aerosol meteorological and climatic effects, air quality monitoring, and public health. To prove their validity and to assess their maturity level, the VIIRS aerosol products were compared to the spatiotemporally matched Aerosol Robotic Network (AERONET) measurements. Over land, the VIIRS aerosol optical thickness (AOT) environmental data record (EDR) exhibits an overall global bias against AERONET of -0.0008 with root-mean-square error (RMSE) of the biases as 0.12. Over ocean, the mean bias of VIIRS AOT EDR is 0.02 with RMSE of the biases as 0.06. The mean bias of VIIRS Ocean Ångström Exponent (AE) EDR is 0.12 with RMSE of the biases as 0.57. The matchups between each product and its AERONET counterpart allow estimates of expected error in each case. Increased uncertainty in the VIIRS AOT and AE products is linked to specific regions, seasons, surface characteristics, and aerosol types, suggesting opportunity for future modifications as understanding of algorithm assumptions improves. Based on the assessment, the VIIRS AOT EDR over land reached Validated maturity beginning 23 January 2013; the AOT EDR and AE EDR over ocean reached Validated maturity beginning 2 May 2012, excluding the processing error period 15 October to 27 November 2012. These findings demonstrate the integrity and usefulness of the VIIRS aerosol products that will transition from S-NPP to future polar-orbiting environmental satellites in the decades to come and become the standard global aerosol data set as the previous generations' missions come to an end.

  3. Long-term Analysis of Aerosol Optical Thickness from Satellite Retrievals over selected large agglomerations

    NASA Astrophysics Data System (ADS)

    Vountas, Marco; von Hoyningen-Huene, Wolfgang; Yoon, Jongmin; Burrows, John P.

    Aside from adverse health effect urban aerosols have potential effects on the climate system. In this study Aerosol Optical Thickness (AOT) retrievals over land are performed to study the medium to long-term trends of aerosols in large agglomerations (aka megacities). This task is challenging because of the high variability of the surface reflectance. The Bremen AErosol Retrieval (BAER) algorithm has retrieved AOT successfully over land with different satellite data in other studies. Here, the annual-and long-term trend of AOT over several regions have been analyzed using BAER based on SeaWiFS (Sea-viewing Wide Field-of-view Sensor) L1b data over a period of 11 years. Among the regions analyzed were several European regions, as well as Sao Paolo, Brazil, and Perl River Delta in south China. Practically all regions investigated showed a week negative trend in AOT (validated by AERONET), except over Perl River Delta where a comparatively strong positive trend of up to 0.007/yr could be observed.

  4. Aerosol extinction and absorption in Evora, Portugal, during the European 2003 summer heat wave

    NASA Astrophysics Data System (ADS)

    Elias, Thierry G.; Silva, Ana M.; Figueira, Maria J.; Belo, Nuno; Pereira, Sergio; Formenti, Paola; Helas, Gunter

    2004-11-01

    Aerosol optical properties are retrieved from measurements acquired during the 2003 summer at the new AERONET station of Evora, Portugal, with a sun/sky photometer, a fluxmeter and a nephelometer. Aerosol optical thickness (aot) derived at several wavelengths shows that an exceptionally long turbid event occurred in July-August. Desert dust particles transported from North Africa increased aot at 873 nm (aot873) to the value of 0.27 with an Ångstrom exponent αC=0.5. Emissions from forest fires in The Iberic peninsula affected Evora since the end of the dust episode, with aot441 reaching 0.81 and aC=1.8. The aerosol scattering coefficient measured at surface level shows that desert dust does not reach the surface level at Evora while the forest fire emissions were uniformly distributed over the atmospheric column. Sky-radiance and flux measurements agree in retrieval of the aerosol single scattering albedo (assa) at several wavelengths. A large absorption rate is found with a high spectral dependence for desert dust particles (assa441=0.86 and ass873=0.93) and with a flat spectral dependence during the forest fires emission episode (assa441=0.88 and assa873=0.87). All measurements as well as back-trajectory calculations indicate mixture of particles during the desert dust.

  5. Retrieval and monitoring of aerosol optical thickness over an urban area by spaceborne and ground-based remote sensing.

    PubMed

    Léon, J F; Chazette, P; Dulac, F

    1999-11-20

    We used an instrumental synergy of both ground-based (sunphotometer) and spaceborne [POLDER (polarization and directionality of the Earth's reflectances) and Meteosat] passive remote-sensing devices to determine the aerosol optical thickness over the suburban area of Thessaloniki, Greece, from April 1996 to June 1997. The POLDER spaceborne instrument measures the degree of polarization of the solar radiance reflected by the Earth-atmosphere system. Aerosol optical thickness (AOT) retrieval needs an accurate estimate of the contribution of the ground surface to the top of atmosphere's polarized radiance. We tested existing surface reflectance models and fitted their parameters to find the best model for the Thessaloniki area. The model was constrained and validated by use of independent data sets of coincident sunphotometer and POLDER measurements. The comparison indicated that the urban AOT over Thessaloniki was retrieved by the POLDER instrument with an accuracy of +/-0.05. From analysis of Meteosat data we found that approximately 40% of the days with high AOT (>0.18) are associated with African dust transport events, all observed in the period March-July. Excluding dust events, the 15-month AOT averages 0.12 +/- 0.04. During the 15-month period that the study was conducted, we observed aerosol pollution peaks with an AOT of >0.24 on 15 of the 164 days on which measurements were possible. PMID:18324235

  6. Fluorescence dynamics of green fluorescent protein in AOT reversed micelles.

    PubMed

    Uskova, M A; Borst, J W; Hink, M A; van Hoek, A; Schots, A; Klyachko, N L; Visser, A J

    2000-09-15

    We have used the enhanced green fluorescent protein (EGFP) to investigate the properties of surfactant-entrapped water pools in organic solvents (reversed micelles) with steady-state and time-resolved fluorescence methods. The surfactant used was sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and the organic solvents were isooctane and (the more viscous) dodecane, respectively. The water content of the water pools could be controlled through the parameter w0, which is the water-to-surfactant molar ratio. With steady-state fluorescence, it was observed that subtle fluorescence changes could be noted in reversed micelles of different water contents. EGFP can be used as a pH-indicator of the water droplets in reversed micelles. Time-resolved fluorescence methods also revealed subtle changes in fluorescence decay times when the results in bulk water were compared with those in reversed micelles. The average fluorescence lifetimes of EGFP scaled with the relative fluorescence intensities. Time-resolved fluorescence anisotropy of EGFP in aqueous solution and reversed micelles yielded single rotational correlation times. Geometrical considerations could assign the observed correlation times to dehydrated protein at low w0 and internal EGFP rotation within the droplet at the highest w0. PMID:11036971

  7. Model-Based Estimation of Sampling-Caused Uncertainty in Aerosol Remote Sensing for Climate Research Applications

    NASA Technical Reports Server (NTRS)

    Geogdzhayev, Igor V.; Cairns, Brian; Mishchenko, Michael I.; Tsigaridis, Kostas; van Noije, Twan

    2014-01-01

    To evaluate the effect of sampling frequency on the global monthly mean aerosol optical thickness (AOT), we use 6 years of geographical coordinates of Moderate Resolution Imaging Spectroradiometer (MODIS) L2 aerosol data, daily global aerosol fields generated by the Goddard Institute for Space Studies General Circulation Model and the chemical transport models Global Ozone Chemistry Aerosol Radiation and Transport, Spectral Radiationtransport Model for Aerosol Species and Transport Model 5, at a spatial resolution between 1.125 deg × 1.125 deg and 2 deg × 3?: the analysis is restricted to 60 deg S-60 deg N geographical latitude. We found that, in general, the MODIS coverage causes an underestimate of the global mean AOT over the ocean. The long-term mean absolute monthly difference between all and dark target (DT) pixels was 0.01-0.02 over the ocean and 0.03-0.09 over the land, depending on the model dataset. Negative DT biases peak during boreal summers, reaching 0.07-0.12 (30-45% of the global long-term mean AOT). Addition of the Deep Blue pixels tempers the seasonal dependence of the DT biases and reduces the mean AOT difference over land by 0.01-0.02. These results provide a quantitative measure of the effect the pixel exclusion due to cloud contamination, ocean sun-glint and land type has on the MODIS estimates of the global monthly mean AOT. We also simulate global monthly mean AOT estimates from measurements provided by pixel-wide along-track instruments such as the Aerosol Polarimetry Sensor and the Cloud-Aerosol LiDAR with Orthogonal Polarization. We estimate the probable range of the global AOT standard error for an along-track sensor to be 0.0005-0.0015 (ocean) and 0.0029-0.01 (land) or 0.5-1.2% and 1.1-4% of the corresponding global means. These estimates represent errors due to sampling only and do not include potential retrieval errors. They are smaller than or comparable to the published estimate of 0.01 as being a climatologically significant

  8. Size and diffusion phenomena of AOT/alcohol/water system in the presence of morin by dynamic light scattering.

    PubMed

    Bhattarai, Ajaya; Wilczura-Wachnik, Hanna

    2015-01-30

    Presented paper is a continuation of our studies on morin interaction with AOT (sodium bis(2-ethylhexyl) sulfosuccinate) reversed micelles solutions in two solvents: ethanol and n-decanol. Now we focused on morin influence on size and diffusion phenomena in the system morin/solvent/AOT/water. In this paper precise measurements of dynamic light scattering (DLS) of the effects of temperature, solvents (alcohols), water on the size and diffusion of AOT reversed micelles in the morin/AOT/alcohol/water system are reported. The concentrations of AOT were varied from 0.51 to 0.78mol/L. Morin concentration in during auto-correlation function registration was not the same in each solvent because of its different solubility depending on the solvent. Water concentration in the studied systems was defined by R parameter according to relation: R=(H2O)/(AOT) and was equal 0 and 30 in ethanol, and 0 in n-decanol. DLS measurements were done at 298.15 and 308.15K. DLS experiment involved on detection two relaxation modes (fast and slow) in the systems containing AOT reversed micelles, water, morin and solvents (ethanol and n-decanol). The DLS data clearly show the solvent influence as well as morin presence on AOT reversed micelles size and consequently their diffusion coefficients. Contrary to n-decanol strong competition between morin and ethanol molecules in AOT reversed micelles palisade layer has been found. It suggests that morin molecules replaced ethanol in AOT reversed micelles and locate in their palisade layer strongly increasing AOT reversed micelles size. Furthermore, it was found a sharp increase in correlation radii of slow modes of AOT reversed micelles containing morin molecules and their diffusion coefficients diminishing. PMID:25448557

  9. Changes in atmospheric aerosol loading from space-based measurements and model simulations for the decade 2001-2010

    NASA Astrophysics Data System (ADS)

    Yoon, J.; Pozzer, A.; Chang, D. Y.; Burrows, J. P.; Lelieveld, J.

    2014-12-01

    This study presents long-term trend estimates of aerosol optical thickness (AOT) retrieved from the space-born instruments (MODIS-Terra, MISR-Terra, SeaWiFS-OrbView-2, and MODIS-Aqua) and simulated by the atmospheric chemistry general circulation model ECHAM5/MESSy (EMAC) for the decade 2001-2010. The satellite-retrieved AOT trends are estimated using the weighted trend method that minimizes the uncertainty effect of unrepresentative monthly means induced by frequent cloud occurrence in cloudy seasons because the AOT products are retrieved from cloud-free radiances by the visible imager. The EMAC simulations distinguish various aerosols components (i.e. black carbon, organic carbon, dust, aerosol water, sea salt, and water soluble compounds) for selected regions and the decomposed trends for each of them. A significant decrease in the satellite-retrieved AOT is estimated over Western Europe (i.e. by up to about -6.59 ± 5.30% per year with a 95% confidence interval) due to the decreasing water-soluble compounds (i.e. ammonium, nitrate and sulphate) and aerosol water content. In contrast, a statistically significant increase is observed over East China (about +5.66 ± 4.14% per year), which is attributed to the increase in black carbon, water-soluble compounds, and aerosol water.

  10. Retrieval of aerosol optical thickness over snow using AATSR observations

    NASA Astrophysics Data System (ADS)

    Istomina, Larysa; von Hoyningen-Huene, Wolfgang; Rozanov, Vladimir; Kokhanovsky, Alexander; Burrows, John P.

    Remote sensing of aerosols experiences lack of products over very bright surfaces, such as deserts and snow, due to difficulties with the subtraction of the surface reflection contribution, when a small error in accounting for surface reflectance can cause a large error in retrieved aerosol optical thickness (AOT). Cloud screening over bright surface is also not easy because of low contrast between clouds and surface in visible range of spectrum, and additional infrared chan-nels are not always available. Luckily, AATSR instrument onboard ENVISAT has necessary features to solve both of these problems. In current work we present an improved version of discussed earlier [1,2] dual-view algorithm to retrieve AOT over snow. The retrieval algorithm still consists of cloud screening, based on spectral shape analysis of AATSR pixel in order to extract clear snow pixels, and of AOT retrieval over snow and water. Current version of AOT retrieval over open ocean now contains improved accounting for ocean reflectance (in previous version the ocean was assumed to be absolutely black). The AOT retrieval over snow has been improved to account more accurately for the bidirectional features of the surface reflection function. For this we now use the approach described in [4] instead of [3], which has been used in the previous version of the retrieval. The accuracy of both approaches [3] and [4] has been evaluated via comparison to forward radiative-transfer model for the case of a very bright surface. The new algorithm has been applied to various scenes in European Arctic and Alaska in different scales, up to global AOT maps. The correspondence of AOT over snow to AOT over water is quite good, which proves the reliability of the retrieval. The algorithm has been validated against AERONET and other Arctic ground based AOT data and shows reasonably good correlation. The presented cloud screening method has been validated via comparison to MODIS cloud mask and Micro Pulse Lidar data

  11. Retrieval of spectral aerosol optical thickness over land using ocean color sensors MERIS and SeaWiFS

    NASA Astrophysics Data System (ADS)

    von Hoyningen-Huene, W.; Yoon, J.; Vountas, M.; Istomina, L. G.; Rohen, G.; Dinter, T.; Kokhanovsky, A. A.; Burrows, J. P.

    2010-05-01

    For the determination of aerosol optical thickness (AOT) Bremen AErosol Retrieval (BAER) has been developed. Method and main influences on the aerosol retrieval are described together with validation and results. The retrieval separates the spectral aerosol reflectance from surface and Rayleigh path reflectance for the shortwave range of the measured spectrum of top-of-atmosphere reflectance less than 0.670 μm. The advantage of MERIS (Medium Resolution Imaging Spectrometer on ENVISAT) and SeaWiFS (Sea viewing Wide Fiels Sensor on OrbView-2) observations are the existence of several spectral channels in the blue and visible range enabling the spectral determination of AOT in 7 (or 6) channels (0.412-0.670 μm) and additionally channels in the NIR, which can be used to characterize the surface properties. A dynamical spectral surface reflectance model for different surface types is used to obtain the spectral surface reflectance for this separation. Normalized differential vegetation index (NDVI), taken from the satellite observations, is the model input. Further surface BRDF is considered by the Raman-Pinty-Verstraete (RPV) model. Spectral AOT is obtained from aerosol reflectance using look-up-tables, obtained from radiative transfer calculations with given aerosol phase functions and single scattering albedos either from aerosol models, given by OPAC or from experimental campaigns. Validations of the obtained AOT retrieval results with AERONET data over Europe gave a preference for experimental phase functions derived from almucantar measurements. Finally long-term observations of SeaWiFS have been investigated for trends in AOT.

  12. Retrieval of aerosol optical thickness fort he EarthCARE Multi-Spectral Imager (MSI)

    NASA Astrophysics Data System (ADS)

    von Hoyningen-Huene, Wolfgang; Kokhanovsky, Alexander; Burrows, John P.; Hesselmans, Gerard; Gale, Leslie; Wandinger, Ulla; Bouvet, Marc; Eisinger, Michael

    2010-05-01

    The future EarthCARE mission is a cloud - aerosol mission and is composed of 4 scientific instruments: a) the HSRL lidar - ATLID, providing vertical profiles of backscatter-, extinction- and depolarization profiles, b) the cloud - precipitation radar - CPR, giving vertical profiles of cloud and precipitation parameters, c) the multi-spectral imager - MSI as an imager with a swath width of 150 km and 0.5 km scene resolution, delivering the cloud and aerosol conditions in the vicinity of the lidar and radar beams and d) the broad band radiometer - BBR, measuring up-welling broad band radiation fluxes. The mission intends to use synergies between the vertical profiles from ATLID and CPR and the area and columnar information on clouds and aerosols from the MSI and the combination of all in the BBR up-welling fluxes. The use of the MSI instrument as imager for aerosol optical thickness (AOT) requires retrieval methods for AOT over ocean and land, which are in development within projects (AMARSI and IRMA), supported by ESA. The algorithm development for the AOT retrieval consists of a target discrimination, the estimation of the surface reflectance and determination of aerosol reflectance, which is used for AOT determination, applying look-up-tables. The algorithms are tested with synthetic data from radiative modelling and MODIS measurements with a selection of the subset of MSI VIS and NIR channels (0.659, 0.865, 1.61 and 2.1 µm). For the instrument performance of MODIS the algorithms developed provide quite comparable AOT with AERONET observations.

  13. Nanoparticles synthesis of tungsten disulfide via AOT-based microemulsions

    SciTech Connect

    Ghoreishi, S.M.; Meshkat, S.S.; Ghiaci, M.; Dadkhah, A.A.

    2012-06-15

    Graphical abstract: A controlled synthesis of WS2 nanoparticles (most probably inorganic fullerene (IF)) via microemulsion was applied for the first time to prepare WS2 (7–12 nm) by acidification of the water cores of the AOT reverse microemulsion. Highlights: ► An innovative reverse microemulsion technique was developed for WS{sub 2} synthesis. ► WS{sub 2} nanoparticles were obtained with narrow size distribution in range of 7–12 nm. ► Operating cost of microemulsion was lower in contrast to quartz reactor method. ► WS{sub 2} morphology could be controlled to obtain highly active and selective catalysts. ► Lower size of WS{sub 2} in this study overcomes the shortcoming of quartz reactor method. -- Abstract: The tungsten disulfide (WS{sub 2}) nanoparticles (most probably inorganic fullerene (IF)) with a narrow size distribution were synthesized by a reverse micelle technique for the first time. The particle size was controlled by varying water-to-surfactant molar ratio (W{sub 0}), aging time and reagent concentration. The synthesized WS{sub 2} nanoparticles were characterized by zetasizer, UV–visible spectrophotometers and transmission electron microscopy (TEM). The WS{sub 2} nanoparticles with particle diameter size of 7–12 nm were obtained via 24 h aging time. The particle size was controlled by changing the aging time and molar ratio of water/surfactant. Doubling W{sub 0} increased the amount and particle size of WS{sub 2} by 22 and 26%, respectively. The effect of aging time in the range of 6–24 h was investigated and the complete disappearance of yellowish color at 24 h resulted in an optically clear solution, which was the indication of WS{sub 2} formation with 100% conversion of reactant ((NH{sub 4}){sub 2}WS{sub 4}) in the batch reactor.

  14. 5. SOUTHWEST PORTAL AND SOUTHWEST WEB OT THROUGH TRUSSES, SHOWING ...

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

    5. SOUTHWEST PORTAL AND SOUTHWEST WEB OT THROUGH TRUSSES, SHOWING TOP CHORD DETAILS; VIEW TO NORTHEAST - Nebraska City Bridge, Spanning Missouri River near Highway 2 between Nebraska & Iowa, Nebraska City, Otoe County, NE

  15. Risk-based evaluation of Allowed Outage Times (AOTs) considering risk of shutdown

    SciTech Connect

    Mankamo, T.; Kim, I.S.; Samanta, P.K.

    1992-12-31

    When safety systems fail during power operation, Technical Specifications (TS) usually limit the repair within Allowed Outage Time (AOT). If the repair cannot be completed within the AOT, or no AOT is allowed, the plant is required to be shut down for the repair. However, if the capability to remove decay heat is degraded, shutting down the plant with the need to operate the affected decay-heat removal systems may impose a substantial risk compared to continued power operation over a usual repair time. Thus, defining a proper AOT in such situations can be considered as a risk-comparison between the repair in frill power state with a temporarily increased level of risk, and the altemative of shutting down the plant for the repair in zero power state with a specific associated risk. The methodology of the risk-comparison approach, with a due consideration of the shutdown risk, has been further developed and applied to the AOT considerations of residual heat removal and standby service water systems of a boiling water reactor (BWR) plant. Based on the completed work, several improvements to the TS requirements for the systems studied can be suggested.

  16. Risk-based evaluation of Allowed Outage Times (AOTs) considering risk of shutdown

    SciTech Connect

    Mankamo, T. ); Kim, I.S.; Samanta, P.K. )

    1992-01-01

    When safety systems fail during power operation, Technical Specifications (TS) usually limit the repair within Allowed Outage Time (AOT). If the repair cannot be completed within the AOT, or no AOT is allowed, the plant is required to be shut down for the repair. However, if the capability to remove decay heat is degraded, shutting down the plant with the need to operate the affected decay-heat removal systems may impose a substantial risk compared to continued power operation over a usual repair time. Thus, defining a proper AOT in such situations can be considered as a risk-comparison between the repair in frill power state with a temporarily increased level of risk, and the altemative of shutting down the plant for the repair in zero power state with a specific associated risk. The methodology of the risk-comparison approach, with a due consideration of the shutdown risk, has been further developed and applied to the AOT considerations of residual heat removal and standby service water systems of a boiling water reactor (BWR) plant. Based on the completed work, several improvements to the TS requirements for the systems studied can be suggested.

  17. Biochemical and structural characterisation of cutinase mutants in the presence of the anionic surfactant AOT.

    PubMed

    Brissos, V; Melo, E P; Martinho, J M G; Cabral, J M S

    2008-09-01

    The reactivity, stability and unfolding of wild-type (WT) Fusarium solani pisi cutinase and L153Q, S54D and T179C variants were studied in the absence and presence of the dioctyl sulfosuccinate sodium salt (AOT) surfactant. In the absence of surfactant the S54D variant catalytic activity is similar to that of the WT cutinase, whereas L153Q and T179C variants show a lower activity. AOT addition induces an activity reduction for WT cutinase and its variants, although for low AOT concentrations a small increase of activity was observed for S54D and T179C. The enzyme deactivation in the presence of 0.5 mM AOT is relatively slow for the S54D and T179C variants when compared to wild-type cutinase and L153Q variant. These results were correlated with secondary and tertiary structure changes assessed by the CD spectrum and fluorescence of the single tryptophan and the six tyrosine residues. The WT cutinase and S54D variant have similar secondary and tertiary structures that differ from those of T179C and L153Q variants. L153Q, S54D and T179C mutations prevent the formation of hydrophobic crevices responsible for the unfolding by anionic surfactants, with the consequent decrease of the AOT-cutinase interactions. PMID:18501723

  18. Global Aerosol Remote Sensing from MODIS

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Kaufman, Yoram J.; Remer, Lorraine A.; Chu, D. Allen; Mattoo, Shana; Tanre, Didier; Levy, Robert; Li, Rong-Rong; Martins, Jose V.; Lau, William K. M. (Technical Monitor)

    2002-01-01

    The physical characteristics, composition, abundance, spatial distribution and dynamics of global aerosols are still very poorly known, and new data from satellite sensors have long been awaited to improve current understanding and to give a boost to the effort in future climate predictions. The derivation of aerosol parameters from the MODerate resolution Imaging Spectro-radiometer (MODIS) sensors aboard the Earth Observing System (EOS) Terra and Aqua polar-orbiting satellites ushers in a new era in aerosol remote sensing from space. Terra and Aqua were launched on December 18, 1999 and May 4, 2002 respectively, with daytime equator crossing times of approximately 10:30 am and 1:30 pm respectively. Several aerosol parameters are retrieved at 10-km spatial resolution (level 2) from MODIS daytime data. The MODIS aerosol algorithm employs different approaches to retrieve parameters over land and ocean surfaces, because of the inherent differences in the solar spectral radiance interaction with these surfaces. The parameters retrieved include: aerosol optical thickness (AOT) at 0.47, 0.55 and 0.66 micron wavelengths over land, and at 0.47, 0.55, 0.66, 0.87, 1.2, 1.6, and 2.1 micron over ocean; Angstrom exponent over land and ocean; and effective radii, and the proportion of AOT contributed by the small mode aerosols over ocean. To ensure the quality of these parameters, a substantial part of the Terra-MODIS aerosol products were validated globally and regionally, based on cross correlation with corresponding parameters derived from ground-based measurements from AERONET (AErosol RObotic NETwork) sun photometers. Similar validation efforts are planned for the Aqua-MODIS aerosol products. The MODIS level 2 aerosol products are operationally aggregated to generate global daily, eight-day (weekly), and monthly products at one-degree spatial resolution (level 3). MODIS aerosol data are used for the detailed study of local, regional, and global aerosol concentration

  19. Blue MASTER OT J020844.29+481923.0 Detection

    NASA Astrophysics Data System (ADS)

    Vladimirov, V.; Zubareva, A.; Lipunov, V.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Pruzhinskaya, M.; Denisenko, D.; Rufanov, V.; Ivanov, K.; Yazev, S.; Budnev, N.; Gress, O.; Poleshchuk, V.; Parkhomenko, E. Konstantinov A.; Tlatov, A.; Dormidontov, D.; Yurkov, V. Senik V.; Sergienko, Y.; Varda, D.; Sinyakov, E.; Gabovich, V.; Krushinsky, V.; Zalozhnih, I.; Popov, A.; Bourdanov, A.; Buckley, D.; Potter, S.; Kniazev, A.; Kotze, M.; Shumkov, V.; Shurpakov, S.

    2015-01-01

    MASTER OT J020844.29+481923.0 - CV? MASTER-Tunka auto-detection system (Lipunov et al., 2010, Advances in Astronomy, vol. 2010, pp. 1, http://adsabs.harvard.edu/abs/2010AdAst2010E..30L) discovered OT source at (RA, Dec) = 02h 08m 44.29s +48d 19m 23.0s on 2015-01-08.52068 UT.

  20. MASTER: OT discovered during inspection of HESE 58537957 trigger

    NASA Astrophysics Data System (ADS)

    Tyurina, N.; Lipunov, V.; Buckley, D.; Gorbovskoy, E.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Kuvshinov, D.; Vlasenko, D.; Gress, O.; Ivanov, K.; Shumkov, V.; Potter, S.

    2016-08-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 13h 08m 45.02s -32d 32m 54.9s on 2016-08-24.73811 UT during inspection of HESE alert ( 58537957 trigger number ) http://gcn.gsfc.nasa.gov/notices_amon/58537957_128340.amon . The OT unfiltered magnitude is 19.6m (limit 20.5m).

  1. MASTER: very bright high amplitude(>7.2m) OT

    NASA Astrophysics Data System (ADS)

    Balanutsa, V.; Balanutsa, P.; Lipunov, V.; Lopez, R. Rebolo; Serra-Ricart, M.; Gorbovskoy, E.; Tiurina, N.; Kornilov, V.; Kuznetsov, A.; Kuvshinov, D.; Vlasenko, D.; Vladiirov, V.; Popova, E.; Chazov, V.; Israelyan, G.; Lodieu, N.; Budnev, N.; Gress, O.; Ivanov, K.

    2016-07-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 20h 53m 16.61s -10d 56m 33.1s on 2016-07-24.10765 UT. The OT unfiltered (W=0.2B+0.8R, calibrated by USNO-B1) magnitude is 14.8 (limit 18.7m).

  2. MASTER-SAAO and MATER-Net OTs detection

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Shumkov, V.; Lipunov, V. M.; Buckley, D. A. H.; Gorbovskoy, E.; Tiurina, N.; Shurpakov, S.; Gress, O.; Kuznetsov, A.; Vladimirov, V.; Kornilov, V.; Vlasenko, D.; Gorbunov, I.; Kniazev, A.; Potter, S. B.; Kotze, M.; Tlatov, A.; Senik, V.; Dormidontov, D.

    2016-03-01

    MASTER-SAAO auto-detection system (Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 07h 28m 58.62s -65d 21m 31.9s on 2016-02-28.87676 UT with unfiltered m_OT=19.0m (the limit is 20.3m).

  3. 12 CFR 502.50 - What fees does OTS charge?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 6 2014-01-01 2012-01-01 true What fees does OTS charge? 502.50 Section 502.50... § 502.50 What fees does OTS charge? (a) The Director assesses fees for examining or investigating... U.S.C. 1462(9), except that, for this part only, “affiliate” does not include any entity that...

  4. OT promotes closer interpersonal distance among highly empathic individuals

    PubMed Central

    Mankuta, David; Shamay-Tsoory, Simone G.

    2015-01-01

    The space between people, or ‘interpersonal distance’, creates and defines the dynamics of social interactions and is a salient cue signaling responsiveness and feeling comfortable. This distance is implicit yet clearly felt, especially if someone stands closer or farther away than expected. Increasing evidence suggests that Oxytocin (OT) serves as a social hormone in humans, and that one of its roles may be to alter the perceptual salience of social cues. Considering that empathic ability may shape the way individuals process social stimuli, we predicted that OT will differentially affect preferred interpersonal distance depending on individual differences in empathy. Participants took part in two interpersonal distance experiments: In the first, they had to stop a (computer visualized) protagonist when feeling most comfortable; in the second, they were asked to choose the room in which they would later discuss intimate topics with another. Both experiments revealed an interaction between the effect of OT and empathy level. Among highly empathic individuals, OT promoted the choice of closer interpersonal distances. Yet, OT had an opposite effect on individuals with low empathic traits. We conclude that the enhancement of social cues following OT administration may have opposite effects on individuals with different empathic abilities. PMID:24509491

  5. OT promotes closer interpersonal distance among highly empathic individuals.

    PubMed

    Perry, Anat; Mankuta, David; Shamay-Tsoory, Simone G

    2015-01-01

    The space between people, or 'interpersonal distance', creates and defines the dynamics of social interactions and is a salient cue signaling responsiveness and feeling comfortable. This distance is implicit yet clearly felt, especially if someone stands closer or farther away than expected. Increasing evidence suggests that Oxytocin (OT) serves as a social hormone in humans, and that one of its roles may be to alter the perceptual salience of social cues. Considering that empathic ability may shape the way individuals process social stimuli, we predicted that OT will differentially affect preferred interpersonal distance depending on individual differences in empathy. Participants took part in two interpersonal distance experiments: In the first, they had to stop a (computer visualized) protagonist when feeling most comfortable; in the second, they were asked to choose the room in which they would later discuss intimate topics with another. Both experiments revealed an interaction between the effect of OT and empathy level. Among highly empathic individuals, OT promoted the choice of closer interpersonal distances. Yet, OT had an opposite effect on individuals with low empathic traits. We conclude that the enhancement of social cues following OT administration may have opposite effects on individuals with different empathic abilities. PMID:24509491

  6. Development the EarthCARE aerosol classification scheme

    NASA Astrophysics Data System (ADS)

    Wandinger, Ulla; Baars, Holger; Hünerbein, Anja; Donovan, Dave; van Zadelhoff, Gerd-Jan; Fischer, Jürgen; von Bismarck, Jonas; Eisinger, Michael; Lajas, Dulce; Wehr, Tobias

    2015-04-01

    The Earth Clouds, Aerosols and Radiation Explorer (EarthCARE) mission is a joint ESA/JAXA mission planned to be launched in 2018. The multi-sensor platform carries a cloud-profiling radar (CPR), a high-spectral-resolution cloud/aerosol lidar (ATLID), a cloud/aerosol multi-spectral imager (MSI), and a three-view broad-band radiometer (BBR). Three out of the four instruments (ATLID, MSI, and BBR) will be able to sense the global aerosol distribution and contribute to the overarching EarthCARE goals of sensor synergy and radiation closure with respect to aerosols. The high-spectral-resolution lidar ATLID obtains profiles of particle extinction and backscatter coefficients, lidar ratio, and linear depolarization ratio as well as the aerosol optical thickness (AOT) at 355 nm. MSI provides AOT at 670 nm (over land and ocean) and 865 nm (over ocean). Next to these primary observables the aerosol type is one of the required products to be derived from both lidar stand-alone and ATLID-MSI synergistic retrievals. ATLID measurements of the aerosol intensive properties (lidar ratio, depolarization ratio) and ATLID-MSI observations of the spectral AOT will provide the basic input for aerosol-type determination. Aerosol typing is needed for the quantification of anthropogenic versus natural aerosol loadings of the atmosphere, the investigation of aerosol-cloud interaction, assimilation purposes, and the validation of atmospheric transport models which carry components like dust, sea salt, smoke and pollution. Furthermore, aerosol classification is a prerequisite for the estimation of direct aerosol radiative forcing and radiative closure studies. With an appropriate underlying microphysical particle description, the categorization of aerosol observations into predefined aerosol types allows us to infer information needed for the calculation of shortwave radiative effects, such as mean particle size, single-scattering albedo, and spectral conversion factors. In order to ensure

  7. Air Quality Monitoring and Forecasting Applications of Suomi NPP VIIRS Aerosol Products

    NASA Astrophysics Data System (ADS)

    Kondragunta, Shobha

    The Suomi National Polar-orbiting Partnership (NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument was launched on October 28, 2011. It provides Aerosol Optical Thickness (AOT) at two different spatial resolutions: a pixel level (~750 m at nadir) product called the Intermediate Product (IP) and an aggregated (~6 km at nadir) product called the Environmental Data Record (EDR), and a Suspended Matter (SM) EDR that provides aerosol type (dust, smoke, sea salt, and volcanic ash) information. An extensive validation of VIIRS best quality aerosol products with ground based L1.5 Aerosol Robotic NETwork (AERONET) data shows that the AOT EDR product has an accuracy/precision of -0.01/0.11 and 0.01/0.08 over land and ocean respectively. Globally, VIIRS mean AOT EDR (0.20) is similar to Aqua MODIS (0.16) with some important regional and seasonal differences. The accuracy of the SM product, however, is found to be very low (20 percent) when compared to Cloud Aerosol Lidar with Orthogonal Polarization (CALIOP) and AERONET. Several algorithm updates which include a better approach to retrieve surface reflectance have been developed for AOT retrieval. For dust aerosol type retrieval, a new approach that takes advantage of spectral dependence of Rayleigh scattering, surface reflectance, dust absorption in the deep blue (412 nm), blue (440 nm), and mid-IR (2.2 um) has been developed that detects dust with an accuracy of ~80 percent. For smoke plume identification, a source apportionment algorithm that combines fire hot spots with AOT imagery has been developed that provides smoke plume extent with an accuracy of ~70 percent. The VIIRS aerosol products will provide continuity to the current operational use of aerosol products from Aqua and Terra MODIS. These include aerosol data assimilation in Naval Research Laboratory (NRL) global aerosol model, verification of National Weather Service (NWS) dust and smoke forecasts, exceptional events monitoring by different states

  8. Performance of megahertz amplified optical time-stretch optical coherence tomography (AOT-OCT).

    PubMed

    Xu, Jingjiang; Wei, Xiaoming; Yu, Luoqin; Zhang, Chi; Xu, Jianbing; Wong, K K Y; Tsia, Kevin K

    2014-09-22

    Enabled by the ultrahigh-speed all-optical wavelength-swept mechanism and broadband optical amplification, amplified optical time-stretch optical coherence tomography (AOT-OCT) has recently been demonstrated as a practical alternative to achieve ultrafast A-scan rate of multi-MHz in OCT. With the aim of identifying the optimal scenarios for MHz operation in AOT-OCT, we here present a theoretical framework to evaluate its performance metric. In particular, the analysis discusses the unique features of AOT-OCT, such as its superior coherence length, and the relationship between the optical gain and the A-scan rate. More importantly, we evaluate the sensitivity of AOT-OCT in the MHz regime under the influence of the amplifier noise. Notably, the model shows that AOT-OCT is particularly promising when operated at the A-scan rate well beyond multi-MHz--not trivially achievable by any existing swept-source OCT platform. A sensitivity beyond 90 dB, close to the shot-noise limit, can be maintained in the range of 2 - 10 MHz with an optical net gain of ~10 dB. Experimental measurement also shows excellent agreement with the theoretical prediction. While distributed fiber Raman amplification is mainly considered in this paper, the theoretical model is generally applicable to any type of amplification schemes. As a result, our analysis serves as a useful tool for further optimization of AOT-OCT system--as a practical alternative to enable MHz OCT operation. PMID:25321720

  9. Complexation of ionomers and surfactant molecules of the same charge in a nonpolar solvent

    SciTech Connect

    Bakeev, K.N.; Chugunov, S.A.; Zezin, A.B.; Kabanov, V.A. . Dept. of Polymer Science); Teraoka, I. ); MacKnight, W.J. . Dept. of Polymer Science and Engineering)

    1994-07-04

    Complexation between sulfonated polystyrene ionomers and bis(2-ethylhexyl) sulfosuccinate sodium salt (aerosol OT, AOT) surfactant molecules in m-xylene was studied by ultracentrifugation, vapor pressure osmometry, viscometry, and dynamic light scattering. When the dilute ionomer solution is mixed with the AOT solution, complexation takes place for both the slightly aggregated state of AOT and reversed micelles of AOT containing water. In the presence of excess AOT molecules, some of the AOT are free from the ionomers, and there are well-defined limiting compositions for complexes of the ionomer and AOT and for those of the ionomer and AOT micelles. The limiting composition depends on the species of the salt or acid group of the ionomer and on the state of AOT before mixing. The composition was estimated to be 0.21--0.66 reversed AOT micelles per salt/acid group for the ionomer--AOT micelles complexes and 14--23 AOT molecules per salt/acid group for the ionomer--AOT complexes. AOT molecules were found to disrupt efficiently the cluster-forming contacts among salt/acid groups, each of them encapsulating a single salt/acid group. The AOT micelles, however, do not completely disrupt the intrachain aggregation.

  10. Photoisomerization and reorientational mobility of symmetric carbocyanines in AOT/alkane/polar solvent microemulsions

    NASA Astrophysics Data System (ADS)

    Dandapat, Manika; Basu, Saswati; Ghosh, Deborin; Mandal, Debabrata

    2014-07-01

    Molecular motion of carbocyanine fluorophores DOCI, DODCI and DTDCI were studied in AOT/n-heptane microemulsions containing added polar solvents: water, methanol or acetonitrile. The response varied remarkably depending on the nature of the fluorophore and polar solvent. When the amount of added polar solvent was low, molecular mobility was invariably retarded, due to a combination of electrostatic and hydrophobic forces that induce the guest fluorophore to cling to the AOT molecules of the host reverse micelle. However, at high amounts of added methanol or water, these interactions diminished considerably, causing increase in the mobility of the guest fluorophores up to different extents.

  11. Flow Properties of Multilamellar Droplets in AOT/Brine/Glycerol Mixtures

    NASA Astrophysics Data System (ADS)

    Ishii, Akiko; Pons, Ramon; Ushiki, Hideharu; Rouch, Jacques; Letamendia, Louis

    2004-09-01

    The properties of lamellar solutions formed in a quaternary mixture made of brine, sodium bis(2-ethylhexyl) sulfosuccinate (AOT), and glycerol have been studied under shear flow. As in AOT, brine pseudo-ternary system, the lamellar solutions exhibit a structural transition above a threshold shear rate, and form quasi-monodispersed multilamellar droplets. In this regime, the solutions are shear thinning. Both the viscosity and the droplet size scale with the shear rate with exponents respectively equal to -0.7 and -0.4. This last value is smaller than the one, 0.5, reported in the ternary systems. Tentative explanations of our experimental results are given.

  12. Influence of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) on zinc electrodeposition

    NASA Astrophysics Data System (ADS)

    Lehr, I. L.; Saidman, S. B.

    2012-03-01

    This work is a study of the electrodeposition of zinc onto SAE 4140 steel electrodes using solutions containing zinc sulfate and bis(2-ethylhexyl) sodium sulfosuccinate (AOT). The influence of different parameters such as electrolyte concentration, electrodeposition time and temperature on the morphology of the electrodeposits was analyzed. The deposits were characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray diffraction. The variation of open circuit potential over time in chloride solutions was also evaluated. The nucleation-growth process and consequently the morphology of the electrodeposits are modified in the presence of AOT. The surfactant induces the formation of a porous deposit.

  13. [Controllable synthesis and UV-Vis spectral analysis of silver nanoparticles in AOT microemulsion].

    PubMed

    Zhang, Wan-Zhong; Qiao, Xue-Liang; Luo, Lang-Li; Chen, Jian-Guo

    2009-03-01

    Colloidal silver nanoparticles were synthesized in water-in-oil microemulsion using silver nitrate solubilized in the water core of a microemulsion as source of silver ions, hydrazine hydrate solubilized in the water core of another one as reducing agent, cyclohexane as the continuous phase, and sodium bis(2-ethylhexyl) sulfosuccinate (AOT) as the surfactant. The main factors affecting the formation of silver nanoparticles were systematically studied. Ultraviolet-visible (UV-Vis) spectra were used for analyzing the effects of reaction parameters, including the type of reducing agents, the molar ratio of water to surfactant and the concentration of AgNO3 and AOT and so on, on the formation of silver nanoparticles. Original results for the controllable synthesis of silver nanoparticles were obtained when the synthesis proceeded in AOT-cyclohexane-AgNO3 microemulsion. The UV-Vis spectra of silver sols formed in the microemulsion with various parameters were studied systematically. The results show that the amount and average size of the obtained nanoparticles obviously depend on the above parameters. When the concentration of AgNO3 is lower, smaller silver nanoparticles are easy to form by increasing the concentration of AgNO3 appropriately. The higher W value was found to form larger numbers of silver nanoparticles with larger particle size. Compared to the solubility of NaBH4 in AOT reverse micelles, hydrazine hydrate is well soluble in these micelles, and thus it is favorable to reduce the silver ions solubilized in the water core of AOT-cyclohexane-AgNO3 microemulsion. The increase in the concentration of AOT induces an increase in the number of AOT micelles and a decrease in the molar ratio of water to surfactant. As a result, the solubilization capacity of reactants in the micelles increases and the radii of the micelles decrease. That is to say, with the increase in AOT concentration, the amount of the formed nanoparticles increases and the average size of the

  14. An Optimal-Estimation-Based Aerosol Retrieval Algorithm Using OMI Near-UV Observations

    NASA Technical Reports Server (NTRS)

    Jeong, U; Kim, J.; Ahn, C.; Torres, O.; Liu, X.; Bhartia, P. K.; Spurr, R. J. D.; Haffner, D.; Chance, K.; Holben, B. N.

    2016-01-01

    An optimal-estimation(OE)-based aerosol retrieval algorithm using the OMI (Ozone Monitoring Instrument) near-ultraviolet observation was developed in this study. The OE-based algorithm has the merit of providing useful estimates of errors simultaneously with the inversion products. Furthermore, instead of using the traditional lookup tables for inversion, it performs online radiative transfer calculations with the VLIDORT (linearized pseudo-spherical vector discrete ordinate radiative transfer code) to eliminate interpolation errors and improve stability. The measurements and inversion products of the Distributed Regional Aerosol Gridded Observation Network campaign in northeast Asia (DRAGON NE-Asia 2012) were used to validate the retrieved aerosol optical thickness (AOT) and single scattering albedo (SSA). The retrieved AOT and SSA at 388 nm have a correlation with the Aerosol Robotic Network (AERONET) products that is comparable to or better than the correlation with the operational product during the campaign. The OEbased estimated error represented the variance of actual biases of AOT at 388 nm between the retrieval and AERONET measurements better than the operational error estimates. The forward model parameter errors were analyzed separately for both AOT and SSA retrievals. The surface reflectance at 388 nm, the imaginary part of the refractive index at 354 nm, and the number fine-mode fraction (FMF) were found to be the most important parameters affecting the retrieval accuracy of AOT, while FMF was the most important parameter for the SSA retrieval. The additional information provided with the retrievals, including the estimated error and degrees of freedom, is expected to be valuable for relevant studies. Detailed advantages of using the OE method were described and discussed in this paper.

  15. An optimal-estimation-based aerosol retrieval algorithm using OMI near-UV observations

    NASA Astrophysics Data System (ADS)

    Jeong, U.; Kim, J.; Ahn, C.; Torres, O.; Liu, X.; Bhartia, P. K.; Spurr, R. J. D.; Haffner, D.; Chance, K.; Holben, B. N.

    2016-01-01

    An optimal-estimation(OE)-based aerosol retrieval algorithm using the OMI (Ozone Monitoring Instrument) near-ultraviolet observation was developed in this study. The OE-based algorithm has the merit of providing useful estimates of errors simultaneously with the inversion products. Furthermore, instead of using the traditional look-up tables for inversion, it performs online radiative transfer calculations with the VLIDORT (linearized pseudo-spherical vector discrete ordinate radiative transfer code) to eliminate interpolation errors and improve stability. The measurements and inversion products of the Distributed Regional Aerosol Gridded Observation Network campaign in northeast Asia (DRAGON NE-Asia 2012) were used to validate the retrieved aerosol optical thickness (AOT) and single scattering albedo (SSA). The retrieved AOT and SSA at 388 nm have a correlation with the Aerosol Robotic Network (AERONET) products that is comparable to or better than the correlation with the operational product during the campaign. The OE-based estimated error represented the variance of actual biases of AOT at 388 nm between the retrieval and AERONET measurements better than the operational error estimates. The forward model parameter errors were analyzed separately for both AOT and SSA retrievals. The surface reflectance at 388 nm, the imaginary part of the refractive index at 354 nm, and the number fine-mode fraction (FMF) were found to be the most important parameters affecting the retrieval accuracy of AOT, while FMF was the most important parameter for the SSA retrieval. The additional information provided with the retrievals, including the estimated error and degrees of freedom, is expected to be valuable for relevant studies. Detailed advantages of using the OE method were described and discussed in this paper.

  16. Rate of Molecular Transfer of Allyl Alcohol across an AOT Surfactant Layer Using Muon Spin Spectroscopy.

    PubMed

    Jayasooriya, Upali A; Clayden, Nigel J; Steytler, David C; Oganesyan, Vasily S; Peck, Jamie N T; Khasanov, Rustem; Scheuermann, Robert; Stoykov, Alexey

    2016-01-26

    The transfer rate of a probe molecule across the interfacial layer of a water-in-oil (w/o) microemulsion was investigated using a combination of transverse field muon spin rotation (TF-μSR), avoided level crossing muon spin resonance (ALC-μSR), and Monte Carlo simulations. Reverse microemulsions consist of nanometer-sized water droplets dispersed in an apolar solvent separated by a surfactant monolayer. Although the thermodynamic, static model of these systems has been well described, our understanding of their dynamics is currently incomplete. For example, what is the rate of solute transfer between the aqueous and apolar solvents, and how this is influenced by the structure of the interface? With an appropriate choice of system and probe molecule, μSR offers a unique opportunity to directly probe these interfacial transfer dynamics. Here, we have employed a well characterized w/o microemulsion stabilized by bis(2-ethylhexyl) sodium sulfosuccinate (Aerosol OT), with allyl alcohol (CH2═CH-CH2-OH, AA) as the probe. Resonances due to both muoniated radicals, CMuH2-C*H-CH2-OH and C*H2-CHMu-CH2-OH, were observed with the former being the dominant species. All resonances displayed solvent dependence, with those in the microemulsion observed as a single resonance located at intermediate magnetic fields to those present in either of the pure solvents. Observation of a single resonance is strong evidence for interfacial transfer being in the fast exchange limit. Monte Carlo calculations of the ΔM = 0 ALC resonances are consistent with the experimental data, indicating exchange rates greater than 10(9) s(-1), placing the rate of interfacial transfer at the diffusion limit. PMID:26716949

  17. Spatio-temporal variability of satellite derived aerosol optical thickness and ground measurements over East China

    NASA Astrophysics Data System (ADS)

    Meng, Fei; Shi, Tongguang

    2016-04-01

    Two-year records of Visible Infrared Imaging Radiometer Suite (VIIRS) Intermediate Product (IP) data on the aerosol optical thickness (AOT) at 550 nm were evaluated by comparing them with sun-sky radiometer measurements from the Chinese sun hazemeter network (CSHNET) and the aerosol robotic network (AERONET). The monthly and seasonal variations in the aerosol optical properties over eastern China were then investigated using collocated VIIRS IP data and CSHNET and AERONET measurements.Results show that the performances of the current VIIRS IP AOT retrievals at the provisional stage were consistent with ground measurements. Similar characteristics of seasonal and monthly variations were found among the measurements, though the observational methodologies were different, showing maxima in the summer and spring and minima in the winter and autumn.

  18. Statistical uncertainty of top of atmosphere cloud-free shortwave Aerosol Radiative Effect

    NASA Astrophysics Data System (ADS)

    Jones, T. A.; Christopher, S. A.

    2007-03-01

    The statistical uncertainty of globally averaged MODIS aerosol optical thickness at 0.55 μm (AOT) and top of atmosphere CERES cloud-free shortwave radiative effect (SWRE) is presented. All analysis is presented at the CERES footprint level which we call "raw data". Statistical uncertainty may result from the raw data not being normally distributed. Both the AOT and SWRE data derived from clear-sky CERES-SSF products show significant deviations from a normal distribution as evidenced by high skewness values. The spatial and temporal distribution of the data is also not uniform, with a greater concentration of data being in aerosol heavy regions. As a result, globally averaged AOT and SWRE are overestimated when derived from raw data. Raw data are gridded into 2×2 degree grid-cells (called "gridded" data) to reduce the effect of spatial non-uniformity. However, the underlying non-normal distribution remains and manifests itself by increasing the uncertainty of grid-cell values. Globally averaged AOT and SWRE derived from a gridded dataset are substantially lower than those derived from raw data alone. The range of globally averaged AOT and SWRE values suggests that up to a 50% statistical uncertainty exists, much of which is directly tied to how the data are manipulated prior to averaging. This uncertainty increases when analyzing aerosol components (e.g. anthropogenic) since component AOT (and SWRE) may not exist at all locations were AOT is present. As a result, regions where a particular component AOT does not exist must either not be included in the global average or have data within these regions set to null values. However, each method produces significantly different results. The results of this work indicate that placing raw observations on to a uniform grid is a necessary step before calculating global statistics. However, this by no means eliminates statistical uncertainty, while adding its own set of assumptions. When reporting any globally averaged

  19. Initial Assessment of NPP/VIIRS Aerosol Environmental Data

    NASA Astrophysics Data System (ADS)

    Laszlo, I.; Kondragunta, S.; Remer, L. A.

    2012-12-01

    The aerosol environment data records (EDR) derived from the measurements of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the recently launched Suomi National Polar-orbiting Partnership (NPP) satellite are the aerosol optical thickness (AOT), aerosol particle size parameter (APSP, characterized in terms of the Angstrom Exponent, AE), and suspended matter (SM). These EDRs go through various evaluations to assess their level of maturity, which are defined by a set of criteria. This presentation provides an overview of the work and results the NPP/JPSS Calibration/Validation Team has performed for the first of the maturity levels, Beta. For this level, the VIIRS AOT and APSP products have been compared with aerosol products derived from MODIS observations onboard the NASA Earth Observing System (EOS) satellite (Aqua), and with AERONET products and observations. SM has been compared with CALIPSO products. All comparisons have been applied to a uniform time sample (2 May 2012 to 2 June 2012). Qualitative and quantitative analysis of the VIIRS aerosol EDRs indicate that AOT both over land and ocean, and APSP over ocean have reached Beta maturity. However, neither APSP over land, nor SM qualifies for Beta level at this time. Qualitatively, one standard deviation of VIIRS AOT EDR products fall within ±0.09 ±10% of collocated MODIS retrievals over land and ±0.02 ±10% over ocean. The same VIIRS product falls within ±0.13 ±15% of collocated AERONET over land and ±0.04 ±5% over ocean. In all cases, the VIIRS AOT over land product is biased high (0.07 to 0.15) against comparable products in a global sense. The VIIRS Angstrom Exponent EDR product over ocean shows correlation when compared with MODIS, but is biased high. Preliminary AERONET analysis at coastal stations shows APSP falling within approximately ±0.40 of AERONET. Preliminary AERONET analysis at coastal stations shows APSP falling within approximately ±0.40 of AERONET. VIIRS Angstrom Exponent

  20. Trend analysis of the Aerosol Optical Thickness and Ångström Exponent derived from the global AERONET spectral observations

    NASA Astrophysics Data System (ADS)

    Yoon, J.; von Hoyningen-Huene, W.; Kokhanovsky, A. A.; Vountas, M.; Burrows, J. P.

    2011-08-01

    Regular aerosol observations based on well-calibrated instruments have led to a better understanding of the aerosol radiative budget on Earth. In recent years, these instruments have played an important role in the determination of the increase of anthropogenic aerosols by means of long-term studies. Only few investigations regarding long-term trends of aerosol optical characteristics (e.g. Aerosol Optical Thickness (AOT) and Ångström Exponent (ÅE)) have been derived from ground-based observations. This paper aims to derive and discuss linear trends of AOT (440, 675, 870, and 1020 nm) and ÅE (440-870 nm) using AErosol RObotic NETwork (AERONET) spectral observations. Additionally, temporal trends of Coarse- and Fine-mode dominant AOTs (CAOT and FAOT) have been estimated by applying an aerosol classification based on accurate ÅE and Ångström Exponent Difference (ÅED). In order to take into account the fact that cloud disturbance is having a significant influence on the trend analysis of aerosols, we introduce a weighted least squares regression depending on two weights: (1) monthly standard deviation and (2) Number of Observations (NO) per month. Temporal increase of FAOTs prevails over regions dominated by emerging economy or slash-burn agriculture in East Asia and South Africa. On the other hand, insignificant or negative trends for FAOTs are detected over Western Europe and North America. Over desert regions, both increase and decrease of CAOTs are observed depending on meteorological conditions.

  1. Variability of aerosol properties over Eastern Europe observed from ground and satellites in the period from 2003 to 2011

    NASA Astrophysics Data System (ADS)

    Bovchaliuk, A.; Milinevsky, G.; Danylevsky, V.; Goloub, P.; Dubovik, O.; Holdak, A.; Ducos, F.; Sosonkin, M.

    2013-01-01

    The paper presents the study of aerosol variability in the period from 2003 to 2011 over Eastern Europe region with latitude ranging from 40° N to 60° N and longitude from 20° E to 50° E. The analysis was based on the POLDER/PARASOL and POLDER-2/ADEOS satellites and AERONET ground-based sunphotometer observations. The aerosol optical thickness (AOT) of the studied area is characterized by the values (referenced to 870 nm wavelength) ranging from 0.05 to 0.2 except the period of July-August 2010 with strong forest and peat wildfires when the AOT typical values range from 0.3 to 0.5. The analysis of seasonal dynamics of aerosol loading has revealed two AOT high value peaks. The first peak observed in April-May is the result of solitary transportation of Sahara dust in the atmosphere over Eastern Europe, infrequent agricultural fires, transportation of sea salt aerosols by southern winds to Ukraine and Moldova from the Black and Azov Seas. The second peak in August-September is associated with forest and peat wildfires, considerable transportation of Sahara dust and presence of soil dust aerosols due to harvesting activity. The maximum values of AOT are observed in May 2006 (0.1-0.15), April 2009 (0.07-0.15) and August 2010 (0.2-0.5). Furthermore, the study has identified a distinct pattern of anthropogenic aerosols over the industrial areas, especially in the central Ukraine, eastern Belarus, as well as Moscow, Nizhny Novgorod and Stavropol regions in Russia. The comparison of the fine mode AOT (particle radius < 0.3 μm) derived by standard algorithm POLDER/PARASOL from reflected polarized radiances with those recomputed from AERONET inversions was performed over a number of AERONET sites: over Kyiv and Sevastopol sites for the period of 2008-2009 and over Moscow, Minsk, Belsk, and Moldova sites for the period of 2005-2009. The correlation coefficients are 0.78 for Moscow, 0.76 - Minsk, 0.86 - Belsk, 0.93 - Kyiv, 0.81 - Moldova and 0.63 for Sevastopol sites. The

  2. Time Series Analysis of Satellie-Measured Vegetation Phenology and Aerosol Optical Thickness over the Korean Peninsula

    NASA Astrophysics Data System (ADS)

    Park, S.

    2015-04-01

    The spatiotemporal influences of climatic factors and atmospheric aerosol on vegetative phenological cycles of the Korean Peninsula was analysed based on four major forest types. High temporal-resolution satellite data can overcome limitations of ground-based phenological studies with reasonable spatial resolution. Moderate Resolution Imaging Spectroradiometer (MODIS) vegetation index (VI) (MOD13Q1 and MYD13Q1) and aerosol (MOD04_D3) data were downloaded from the USGS Earth Observation and Science (EROS) Data Center and NASA Goddard Space Flight Center. Harmonic analysis was used to describe and compare the periodic phenomena of the vegetative phenology and atmospheric aerosol optical thickness (AOT). The method transforms complex timeseries to a sum of various sinusoidal functions, or harmonics. Each harmonic curve, or term (or Fourier series), from time-series data us defined by a unique amplitude and a phase, indicating the half of the height and the peak time of a curve. Therefore, the mean, phase, and amplitude of harmonic terms of the data provided the temporal relationships between AOT and VI time series. The phenological characteristics of evergreen forest, deciduous forest, and grassland were similar to each other, but the inter-annual VI amplitude of mixed forest was differentiated from the other forest types. Overall, forests with high VI amplitude reached their maximum greenness earlier, and the phase of VI, or the peak time of greenness, was significantly influenced by air temperature. AOT time-series showed strong seasonal and inter-annual variations. Generally, aerosol concentrations were peaked during late spring and early summer. However, inter-annual AOT variations did not have significant relationships with those of VI. Weak relationships between inter-annual AOT and VI variations indicate that the impacts of aerosols on vegetation growth may be limited for the temporal scale investigated in the region.

  3. Long term aerosol and trace gas measurements in Central Amazonia

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo; Barbosa, Henrique M. J.; Ferreira de Brito, Joel; Carbone, Samara; Rizzo, Luciana V.; Andreae, Meinrat O.; Martin, Scot T.

    2016-04-01

    The central region of the Amazonian forest is a pristine region in terms of aerosol and trace gases concentrations. In the wet season, Amazonia is actually one of the cleanest continental region we can observe on Earth. A long term observational program started 20 years ago, and show important features of this pristine region. Several sites were used, between then ATTO (Amazon Tall Tower Observatory) and ZF2 ecological research site, both 70-150 Km North of Manaus, receiving air masses that traveled over 1500 km of pristine tropical forests. The sites are GAW regional monitoring stations. Aerosol chemical composition (OC/EC and trace elements) is being analysed using filters for fine (PM2.5) and coarse mode aerosol as well as Aerodyne ACSM (Aerosol Chemical Speciation Monitors). VOCs are measured using PTR-MS, while CO, O3 and CO2 are routinely measured. Aerosol absorption is being studied with AE33 aethalometers and MAAP (Multi Angle Absorption Photometers). Aerosol light scattering are being measured at several wavelengths using TSI and Ecotech nephelometers. Aerosol size distribution is determined using scanning mobility particle sizer at each site. Lidars measure the aerosol column up to 12 Km providing the vertical profile of aerosol extinction. The aerosol column is measures using AERONET sun photometers. In the wet season, organic aerosol comprises 75-85% of fine aerosol, and sulfate and nitrate concentrations are very low (1-3 percent). Aerosols are dominated by biogenic primary particles as well as SOA from biogenic precursors. Black carbon in the wet season accounts for 5-9% of fine mode aerosol. Ozone in the wet season peaks at 10-12 ppb at the middle of the day, while carbon monoxide averages at 50-80 ppb. Aerosol optical thickness (AOT) is a low 0.05 to 0.1 at 550 nm in the wet season. Sahara dust transport events sporadically enhance the concentration of soil dust aerosols and black carbon. In the dry season (August-December), long range transported

  4. "Snap-shooting" the interface of AOT reverse micelles: use of chemical trapping

    PubMed

    Srilakshmi; Chaudhuri

    2000-08-01

    The first use of the phenyl cation trapping technique in "snap-shooting" the local molar concentrations of water and sulfosuccinate head-groups in the interfacial region of AOT-2,2,4-trimethylpentane-water reverse micelles has been accomplished. Our results demonstrate that the interfacial concentrations of the sulfosuccinate head-groups in AOT (0.1 M)-2,2,4-trimethylpentane-water reverse micelles are remarkably high (2.75-2.34 M) across the W0 (the molar ratio of water to surfactant) range 12 to 44. However, the interfacial concentrations of water in AOT- 2,2,4-trimethylpentane-water reverse micelles across the same range of solution compositions are significantly lower (27.9-32.0 M) than the molar concentration of bulk water (55.5 M). The present results provide new insight on the microenvironments of interfacially located enzymes such as lipases entrapped in AOT-2,2,4-trimethylpentane-water reverse micelles, the most extensively exploited reverse-micellar system in micellar biotechnology. PMID:10985732

  5. Improvement in extraction and catalytic activity of Mucor javanicus lipase by modification of AOT reverse micelle.

    PubMed

    Talukder, Mahabubur Rahman; Susanto, Diana; Feng, Gao; Wu, Jinchuan; Choi, Won Jae; Chow, Yvonne

    2007-11-01

    Reverse micelles are formed in apolar solvents by spontaneous aggregation of surfactants. Surfactant sodium bis (2-ethylhexyl) sulfosuccinate (AOT) is most often used for the reverse micellar extraction of enzymes. However, the inactivation of enzyme due to strong interaction with AOT molecules is a severe problem. To overcome this problem, the AOT/water/isooctane reverse micellar system was modified by adding short chain polyethylene glycol 400 (PEG 400). The modified AOT reverse micellar system was used to extract Mucor javanicus lipase from the aqueous phase to the reverse micellar phase. The extraction efficiency (E) increased with the increase in PEG 400 addition and the maximum E in PEG 400 modified system was twofold higher than that in the PEG 400-free system. Upon addition of PEG 400, the water activity (a(w)) of aqueous phase decreased, whereas a(w) of reverse micellar phase increased. The circular dichroism spectroscopy analysis revealed that PEG 400 changes the secondary and tertiary structure of lipase. The maximum specific activity of lipase extracted in PEG 400-modified reverse micellar system was threefold higher than that in the PEG-free system. PMID:17639532

  6. Seasonal variation and difference of aerosol optical properties in columnar and surface atmospheres over Shanghai

    NASA Astrophysics Data System (ADS)

    Cheng, Tiantao; Xu, Chen; Duan, Junyan; Wang, Yifan; Leng, Chunpeng; Tao, Jun; Che, Huizheng; He, Qianshan; Wu, Yunfei; Zhang, Renjian; Li, Xiang; Chen, Jianmin; Kong, Lingdong; Yu, Xingna

    2015-12-01

    Aerosol optical properties in columnar and surface atmospheres were measured at an urban station of Shanghai from December 2010 to October 2012, and their seasonal variations and differences were examined. Aerosol optical thickness (AOT) at 500 nm is on average about 0.72 over the entire campaign, relatively higher in spring and summer and lower in autumn and winter. Ångström wavelength exponent (Alfa) mainly distributes in 1.1-1.6 (72%) with an obvious uni-peak pattern, implying that fine particles are primary in the aerosol group. Aerosol single scattering albedo of columnar atmosphere (SSA) at 440 nm experiences a weak seasonal variation with an average of 0.91, indicating that aerosols are mainly composed of particles with relatively higher scattering efficiency. The aerosol volume size distribution shows one fine mode and another coarse mode, with peak radii of 0.15 μm and 3.0 μm, respectively. The volume of fine mode particles is minimum in spring and maximum in summer, while the volume of coarse mode particles is minimum in autumn and maximum in winter. The scattering coefficient (Sc) of aerosols in surface atmosphere is relatively higher in winter and spring, the absorptive coefficient (Ab) is higher in autumn and summer. The SSA of surface atmosphere (SSA-surf) at 532 nm varies weakly over time with a lower deviation, mostly scattering in the range of 0.8-0.95 (82%). Although the disconnection of aerosol properties between columnar and surface atmospheres exists, AOT and Alfa are correlated to some extent with PM2.5 and visibility. However, the difference of SSA and SSA-surf is remarkable about 0.1. Overall, fine particles are dominant in aerosols and contribute to AOT significantly in this city, and their difference between surface and columnar atmospheres is unignored.

  7. Enhanced Deep Blue aerosol retrieval algorithm: The second generation

    NASA Astrophysics Data System (ADS)

    Hsu, N. C.; Jeong, M.-J.; Bettenhausen, C.; Sayer, A. M.; Hansell, R.; Seftor, C. S.; Huang, J.; Tsay, S.-C.

    2013-08-01

    The aerosol products retrieved using the Moderate Resolution Imaging Spectroradiometer (MODIS) collection 5.1 Deep Blue algorithm have provided useful information about aerosol properties over bright-reflecting land surfaces, such as desert, semiarid, and urban regions. However, many components of the C5.1 retrieval algorithm needed to be improved; for example, the use of a static surface database to estimate surface reflectances. This is particularly important over regions of mixed vegetated and nonvegetated surfaces, which may undergo strong seasonal changes in land cover. In order to address this issue, we develop a hybrid approach, which takes advantage of the combination of precalculated surface reflectance database and normalized difference vegetation index in determining the surface reflectance for aerosol retrievals. As a result, the spatial coverage of aerosol data generated by the enhanced Deep Blue algorithm has been extended from the arid and semiarid regions to the entire land areas. In this paper, the changes made in the enhanced Deep Blue algorithm regarding the surface reflectance estimation, aerosol model selection, and cloud screening schemes for producing the MODIS collection 6 aerosol products are discussed. A similar approach has also been applied to the algorithm that generates the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) Deep Blue products. Based upon our preliminary results of comparing the enhanced Deep Blue aerosol products with the Aerosol Robotic Network (AERONET) measurements, the expected error of the Deep Blue aerosol optical thickness (AOT) is estimated to be better than 0.05 + 20%. Using 10 AERONET sites with long-term time series, 79% of the best quality Deep Blue AOT values are found to fall within this expected error.

  8. Issues in Data Fusion for Satellite Aerosol Measurements for Applications with GIOVANNI System at NASA GES DISC

    NASA Technical Reports Server (NTRS)

    Gopalan, Arun; Zubko, Viktor; Leptoukh, Gregory G.

    2008-01-01

    We look at issues, barriers and approaches for Data Fusion of satellite aerosol data as available from the GES DISC GIOVANNI Web Service. Daily Global Maps of AOT from a single satellite sensor alone contain gaps that arise due to various sources (sun glint regions, clouds, orbital swath gaps at low latitudes, bright underlying surfaces etc.). The goal is to develop a fast, accurate and efficient method to improve the spatial coverage of the Daily AOT data to facilitate comparisons with Global Models. Data Fusion may be supplemented by Optimal Interpolation (OI) as needed.

  9. Smoke aerosol and its radiative effects during extreme fire event over Central Russia in summer 2010

    NASA Astrophysics Data System (ADS)

    Chubarova, N.; Nezval', Ye.; Sviridenkov, I.; Smirnov, A.; Slutsker, I.

    2012-03-01

    Different microphysical, optical and radiative properties of aerosol were analyzed during the severe fires in summer 2010 over Central Russia using ground measurements at two AERONET sites in Moscow (Meteorological Observatory of Moscow State University - MSU MO) and Zvenigorod (Moscow Region) and radiative measurements at the MSU MO. Volume aerosol size distribution in smoke conditions had a bimodal character with the significant prevalence of fine mode particles, for which effective radius was shifted to higher values (reff-fine = 0.24 μm against approximately 0.15 μm in typical conditions). For smoke aerosol, the imaginary part of refractive index (REFI) in the visible spectral region was lower than that for typical aerosol (REFIλ =675 nm = 0.006 against REFIλ =675 nm = 0.01), while single scattering albedo (SSA) was significantly higher (SSAλ =675 nm = 0.95 against SSAλ =675 nm ~ 0.9). Extremely high aerosol optical thickness at 500 nm (AOT500) was observed on 6-8 August reaching the absolute maximum on 7 August in Moscow (AOT500 = 6.4) and at Zvenigorod (AOT500 = 5.9). A dramatic attenuation of solar irradiance at ground was also recorded. Maximum irradiance loss had reached 64% for global shortwave irradiance, 91% for UV radiation 300-380 nm, and 97% for erythemally-weighted UV irradiance at relatively high solar elevation 47°. Significant spectral dependence in attenuation of solar irradiance in smoky conditions was mainly explained by higher AOT and smaller SSA in UV (0.8-0.9) compared with SSA in the visible region of spectrum. The assessments of radiative forcing effect (RFE) at the TOA indicated a significant cooling of the smoky atmosphere. Instant RFE reached -167 Wm-2 at AOT500 = 6.4, climatological RFE calculated with August 2010 monthly mean AOT was about -65 Wm-2, compared with -20 Wm-2 for typical aerosol according to the 10 yr period of measurements in Moscow.

  10. Comparison of In Situ Aerosol Data from the ACE-Asia 2001 Experiment

    NASA Astrophysics Data System (ADS)

    Knobelspiesse, K. D.; Pietras, C.; Miller, M. A.; Reynolds, R. M.; Frouin, R.; Quinn, P. K.; Deschamps, P. Y.; Werdell, P. J.; Fargion, G. S.

    2002-05-01

    The Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) is an international, multidisciplinary project to further knowledge about atmospheric aerosols. ACE-Asia included an intensive field measurement campaign during the spring of 2001 off the coasts of China, Japan and Korea. The Sensor Intercomparison and Merger for Biological and Interdisciplinary Oceanic Studies (SIMBIOS) Project participated in the ACE-Asia cruise of the R/V Ronald H. Brown, which departed from Hawaii on 2001/03/15, sailed west to the Sea of Japan, and finished in Yokosuka, Japan on 2001/04/19. The SIMBIOS Project compares and merges data projects from multiple ocean color missions. As In Situ data are essential for merger and comparison of satellite ocean color measurements, the Project is interested in instrumentation devopment and data base building. The SeaWiFS Bio-optical Archive and Storage System (SeaBASS) is the database used and maintained by the SIMBIOS project. The ACE-Asia cruise was an excellent opportunity to compare data from a variety of maritime sun photometers, as several aerosol conditions were experienced. These included low Aerosol Optical Thickness (AOT) maritime conditions near Hawaii and extremely high AOT dust conditions in the Sea of Japan. Concurrant measurements were made with the PREDE POM-01 Mark II radiometer, a Laboratoire d'Optique Atmosphérique (LOA) SIMBAD, a Laboratorie d'Optique Atmosphérique (LOA) SIMBAD-a, two Solar Light, Inc. Microtops II's, and Brookhaven National Laboratory's Fast Rotating Shadowband Radiometer (FRSR). In addition, a Micro Pulse Lidar (MPL) was deployed that provides vertical aerosol distributions. Data were processed utilizing new algorithms to screen errors due to improper pointing at the sun, a problem previously recognized for the Microtops II. Comparisons of AOT at 500nm and Angstrom Exponent were made for all the instruments. The hand held, direct solar sun photometers (Microtops II, SIMBAD and SIMBADa

  11. Evaluations of Thin Cirrus Contamination and Screening in Ground Aerosol Observations Using Collocated Lidar Systems

    NASA Technical Reports Server (NTRS)

    Huang, Jingfeng; Hsu, N. Christina; Tsay, Si-Chee; Holben, Brent N.; Welton, Ellsworth J.; Smirnov, Alexander; Jeong, Myeong-Jae; Hansell, Richard A.; Berkoff, Timothy A.

    2012-01-01

    Cirrus clouds, particularly sub visual high thin cirrus with low optical thickness, are difficult to be screened in operational aerosol retrieval algorithms. Collocated aerosol and cirrus observations from ground measurements, such as the Aerosol Robotic Network (AERONET) and the Micro-Pulse Lidar Network (MPLNET), provide us with an unprecedented opportunity to examine the susceptibility of operational aerosol products to thin cirrus contamination. Quality assured aerosol optical thickness (AOT) measurements were also tested against the CALIPSO vertical feature mask (VFM) and the MODIS-derived thin cirrus screening parameters for the purpose of evaluating thin cirrus contamination. Key results of this study include: (1) Quantitative evaluations of data uncertainties in AERONET AOT retrievals are conducted. Although AERONET cirrus screening schemes are successful in removing most cirrus contamination, strong residuals displaying strong spatial and seasonal variability still exist, particularly over thin cirrus prevalent regions during cirrus peak seasons, (2) Challenges in matching up different data for analysis are highlighted and corresponding solutions proposed, and (3) Estimation of the relative contributions from cirrus contamination to aerosol retrievals are discussed. The results are valuable for better understanding and further improving ground aerosol measurements that are critical for aerosol-related climate research.

  12. A new method of satellite-based haze aerosol monitoring over the North China Plain and a comparison with MODIS Collection 6 aerosol products

    NASA Astrophysics Data System (ADS)

    Yan, Xing; Shi, Wenzhong; Luo, Nana; Zhao, Wenji

    2016-05-01

    With worldwide urbanization, hazy weather has been increasingly frequent, especially in the North China Plain. However, haze aerosol monitoring remains a challenge. In this paper, MODerate resolution Imaging Spectroradiometer (MODIS) measurements were used to develop an enhanced haze aerosol retrieval algorithm (EHARA). This method can work not only on hazy days but also on normal weather days. Based on 12-year (2002-2014) Aerosol Robotic Network (AERONET) aerosol property data, empirical single scattering albedo (SSA) and asymmetry factor (AF) values were chosen to assist haze aerosol retrieval. For validation, EHARA aerosol optical thickness (AOT) values, along with MODIS Collection 6 (C6) dark-pixel and deep blue aerosol products, were compared with AERONET data. The results show that the EHARA can achieve greater AOT spatial coverage under hazy conditions with a high accuracy (73% within error range) and work a higher resolution (1-km). Additionally, this paper presents a comprehensive discussion of the differences between and limitations of the EHARA and the MODIS C6 DT land algorithms.

  13. Understanding The Correlation of San Joaquin Air Quality Monitoring With Aerosol Optical Thickness Satellite Measurements

    NASA Astrophysics Data System (ADS)

    Ballard, M.; Newcomer, M.; Rudy, J.; Lake, S.; Sambasivam, S.; Strawa, A. W.; Schmidt, C.; Skiles, J.

    2007-12-01

    Air quality in the San Joaquin Valley (SJV) has failed to meet state and federal attainment standards for Particulate Matter (PM) for several years. Air quality agencies currently use ground monitoring sites to monitor air quality in the San Joaquin Valley. This method provides accurate information at specific points but does not provide a clear indication of what is occurring over large regions. Using measurements from satellite imagery has the potential to provide valuable air quality information in a timely manner across large regions. While previous studies show good correlations between satellite derived Aerosol Optical Thickness (AOT) and surface PM measurements on the East Coast of the United States, the data do not correlate well in the SJV. This paper compares PM2.5 ground data from the California Air Resources Board (CARB) and the Interagency Monitoring of Protected Environments (IMPROVE) sites with satellite data in an effort to understand this discrepancy. To verify satellite AOT value accuracy, ground AOT values were collected from the Aerosol Robotic Network (AERONET) and from measurements using the hand-held MicroTops II Sun Photometer field instrument. We found good correlation of the AOT values between MODIS, MISR and AERONET. However, we found poor correlations between satellite- based AOT values and PM2.5 values, and consideration of aerosol speciation did not improve the correlations. Further investigation is needed to determine the causes of the poor correlation. Acquiring detailed information on the meteorological conditions and vertical profiles of the atmosphere using ground-based LIDAR or data from CALIPSO may provide better results.

  14. 12 CFR 563b.115 - How will OTS review my business plan?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... FROM MUTUAL TO STOCK FORM Standard Conversions Prior to Conversion § 563b.115 How will OTS review my... with the Regional Office. OTS may request additional information, if necessary, to support...

  15. 12 CFR 563b.115 - How will OTS review my business plan?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... FROM MUTUAL TO STOCK FORM Standard Conversions Prior to Conversion § 563b.115 How will OTS review my... with the Regional Office. OTS may request additional information, if necessary, to support...

  16. 12 CFR 563b.115 - How will OTS review my business plan?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... FROM MUTUAL TO STOCK FORM Standard Conversions Prior to Conversion § 563b.115 How will OTS review my... with the Regional Office. OTS may request additional information, if necessary, to support...

  17. 12 CFR 563b.115 - How will OTS review my business plan?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... FROM MUTUAL TO STOCK FORM Standard Conversions Prior to Conversion § 563b.115 How will OTS review my... with the Regional Office. OTS may request additional information, if necessary, to support...

  18. Mapping atmospheric aerosols with a citizen science network of smartphone spectropolarimeters

    NASA Astrophysics Data System (ADS)

    Snik, Frans; Rietjens, Jeroen H. H.; Apituley, Arnoud; Volten, Hester; Mijling, Bas; Di Noia, Antonio; Heikamp, Stephanie; Heinsbroek, Ritse C.; Hasekamp, Otto P.; Smit, J. Martijn; Vonk, Jan; Stam, Daphne M.; Harten, Gerard; Boer, Jozua; Keller, Christoph U.

    2014-10-01

    To assess the impact of atmospheric aerosols on health, climate, and air traffic, aerosol properties must be measured with fine spatial and temporal sampling. This can be achieved by actively involving citizens and the technology they own to form an atmospheric measurement network. We establish this new measurement strategy by developing and deploying iSPEX, a low-cost, mass-producible optical add-on for smartphones with a corresponding app. The aerosol optical thickness (AOT) maps derived from iSPEX spectropolarimetric measurements of the daytime cloud-free sky by thousands of citizen scientists throughout the Netherlands are in good agreement with the spatial AOT structure derived from satellite imagery and temporal AOT variations derived from ground-based precision photometry. These maps show structures at scales of kilometers that are typical for urban air pollution, indicating the potential of iSPEX to provide information about aerosol properties at locations and at times that are not covered by current monitoring efforts.

  19. Dust aerosol retrieval results from MISR (multi-angle imaging spectro-radiometer)

    NASA Technical Reports Server (NTRS)

    Kalashnikova, Olga V.; Diner, David J.; Kahn, Ralph; Gaitley, Barbara

    2004-01-01

    Satellite measurements provide important tools for understanding the effect of mineral dust aerosols on past and present climate and climate predictions. Multi-angle instruments such as Multi-angle Imaging Spectro- Radiometer (MISR) provide independent constraints on aerosol properties based on their sensitivity to the shape of aerosol scattering phase functions. The current MISR operational retrieval algorithm (version 16 and higher) was modified by incorporating new non-spherical dust models that account for naturally occurring dust shapes and compositions. We present selected examples of MISR version 16 retrievals over AERONET sunphotometer land and ocean sites during the passage of dust fronts. Our analysis shows that during such events MISR retrieves Angstrom exponents characteristic of large particles, having little spectral variation in extinction over the MISR wavelength range (442, 550, 672 and 866 nm channels), as expected. The retrieved fraction of non-spherical particles is also very high. This quantity is not retrieved by satellite instruments having only nadir-viewing cameras. Our comparison of current (version 16) MISR-retrieved aerosol optical thickness (AOT) with AERONET instantaneous AOT shows better coverage and stronger correlations than when making identical comparisons with previous AOT retrievals (version 15). The MISR algorithm successful mixtures include a non-spherical dust component with high frequency in retrievals over dark water and slightly lower frequency over land. Selection frequencies of non-spherical dust models also decrease in dusty regions affected by pollution.

  20. MAPPING ANNUAL MEAN GROUND-LEVEL PM2.5 CONCENTRATIONS USING MULTIANGLE IMAGING SPECTRORADIOMETER AEROSOL OPTICAL THICKNESS OVER THE CONTIGUOUS UNITED STATES

    EPA Science Inventory

    We present a simple approach to estimating ground-level fine particle (PM2.5, particles smaller than 2.5 um in diameter) concentration using global atmospheric chemistry models and aerosol optical thickness (AOT) measurements from the Multi- angle Imaging SpectroRadiometer (MISR)...

  1. Counterpart of MASTER OT J084140.94+722732.6

    NASA Astrophysics Data System (ADS)

    Nesci, Roberto

    2016-02-01

    Following the ATel #8725 by Balanutsa et al. about MASTER OT J084140.94+722732.6, I made aperture photometry on all the Palomar survey plates (12) available from the MAST archive to get an indication of the star color.

  2. 12 CFR 563.143 - Must I file with OTS?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Must I file with OTS? 563.143 Section 563.143... (including the proposed capital distribution) for the applicable calendar year exceeds your net income for that year to date plus your retained net income for the preceding two years Must file an...

  3. 12 CFR 500.10 - The OTS or The Office.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false The OTS or The Office. 500.10 Section 500.10 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY AGENCY ORGANIZATION AND... supervision of savings associations by regulatory staff to ensure the safety and soundness of the industry....

  4. Supramolecular assemblies obtained by mixing different cyclodextrins and AOT or BHDC reverse micelles.

    PubMed

    Silva, O Fernando; Correa, N Mariano; Silber, Juana J; de Rossi, Rita H; Fernández, Mariana A

    2014-04-01

    In this contribution we show the effect of the surfactant polar head and the external solvent on the incorporation of different cyclodextrins (CDs) {α-CD, β-CD, γ-CD, decenylsuccinyl-β-CD (Mod-β-CD), and hydroxypropyl-β-CD (hp-β-CD)} in different reverse micelles (RMs) {benzene/sodium 1,4-bis(2-ethylhexyl) sulfosuccinate(AOT)/water, and benzene/benzyl-n-hexadecyldimethylammonium chloride (BHDC)/water} and compare them with previous results obtained in n-heptane/AOT/water RMs. To investigate the different systems, we have used UV-vis spectrophotometry, induced circular dichroism spectroscopy (ICD), and the achiral molecular probe methyl orange (MO). The results show dramatic differences changing the external solvent and the surfactant, which are explained by considering the differences in the RMs interface composition, the water-surfactant interaction, and the CDs' location in the different media investigated. None of the CDs were incorporated into the benzene/AOT/water RMs at any [H2O]/[surfactant] ratio studied (W0) whereas it was previously shown that Mod-β-CD and hp-β-CD could be included in n-heptane/AOT/water RMs. However, all of the CDs are incorporated in benzene/BHDC/water RMs at W0 > 10 and hp-β-CD is dissolved even at W0 = 0. Different from what was found in n-heptane/AOT RMs, in BHDC RMs MO showed ICD signals with two different CDs: Mod-β-CD and hp-β-CD. The results are explained by considering the known difference in the interfacial water structure for AOT and BHDC RMs and the electron-rich region on the secondary hydroxyl (wider side of the CDs), which helps to solubilize all CDs in BHDC. This study shows that chiral cyclodextrin could be available for a guest in an organic medium such as the RMs. Therefore we have created a potentially powerful nanoreactor with two different confined regions in the same aggregate: the polar core of the RMs and the chiral hydrophobic cavity of cyclodextrin. PMID:24597759

  5. 12 CFR 516.270 - How long is the OTS review period?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false How long is the OTS review period? 516.270 Section 516.270 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY APPLICATION PROCESSING PROCEDURES OTS Review Standard Treatment § 516.270 How long is the OTS review period? (a)...

  6. 12 CFR 516.270 - How long is the OTS review period?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 6 2012-01-01 2012-01-01 false How long is the OTS review period? 516.270 Section 516.270 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY APPLICATION PROCESSING PROCEDURES OTS Review Standard Treatment § 516.270 How long is the OTS review period? (a)...

  7. 12 CFR 516.270 - How long is the OTS review period?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 6 2014-01-01 2012-01-01 true How long is the OTS review period? 516.270 Section 516.270 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY APPLICATION PROCESSING PROCEDURES OTS Review Standard Treatment § 516.270 How long is the OTS review period? (a)...

  8. 12 CFR 563b.115 - How will OTS review my business plan?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false How will OTS review my business plan? 563b.115... business plan? (a) OTS will review your business plan to determine that it demonstrates a safe and sound... will be determinative. OTS will review every case on its merits. (b) You must file your business...

  9. 12 CFR 585.120 - What factors will OTS consider in reviewing my application?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false What factors will OTS consider in reviewing my application? 585.120 Section 585.120 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE... OTS consider in reviewing my application? (a) OTS review. (1) In determining whether to approve...

  10. Teaching the Moving Child: OT Insights That Will Transform Your K-3 Classroom

    ERIC Educational Resources Information Center

    Berkey, Sybil M.

    2009-01-01

    Because sensorimotor and environmental factors have a profound effect on children's learning, every teacher should know how to weave strategies from occupational therapy (OT) into their everyday instruction. This is the guidebook K-3 teachers need to "think like an OT"--and form effective partnerships with OTs in their schools--so all students can…

  11. 12 CFR 550.560 - When may the OTS revoke my fiduciary powers?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false When may the OTS revoke my fiduciary powers? 550.560 Section 550.560 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY... § 550.560 When may the OTS revoke my fiduciary powers? The OTS may revoke your fiduciary powers if...

  12. 12 CFR 550.120 - What action will the OTS take on my application?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false What action will the OTS take on my application... FIDUCIARY POWERS OF SAVINGS ASSOCIATIONS Obtaining Fiduciary Powers § 550.120 What action will the OTS take... OTS may impose conditions to ensure that the requirements of this part are met....

  13. 12 CFR 563b.200 - What actions may OTS take on my application?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false What actions may OTS take on my application....200 What actions may OTS take on my application? (a) OTS may approve your application for conversion only if: (1) Your conversion complies with this part; (2) You will meet your regulatory...

  14. Real Effect or Artifact of Cloud Cover on Aerosol Optical Thickness?

    SciTech Connect

    Jeong, M-J.; Li, Z.

    2005-03-18

    Aerosol measurements over the Southern Great Plains (SGP) Cloud And Radiation Test bed (CART) site under Department of Energy's (DOE) Atmospheric Radiation Measurement (ARM) program characterize the temporal variability, vertical distribution, and optical properties of aerosols in the region. They were made by the Cimel sunphotometer and Multifilter Rotating Shadow-band Radiometer (MFRSR), Raman Lidar, In situ Aerosol Profiling (IAP) flights, and the Aerosol Observing System (AOS). The spatial variability of aerosols relies a network of MFRSR at the Central Facility (CF) and Extended Facilities (EF), together with satellite remote sensing. The current state-of-art satellite-based estimates over land--e.g., MODerate resolution Imaging Scanner (MODIS) aerosol optical thickness--still suffer from large uncertainties. Contamination due to sub-pixel and/or thin cirrus clouds is believed to be one of the major sources of uncertainties. Retrievals near clouds are discouraged to use, which reduces considerably the amount of useful data. In this regard, cloud is considered as an artifact. However, cloud could have a real impact on AOT by changing humidity, which affects aerosol through the aerosol swelling effect. As a preliminary study, we first investigate the effects of cloud cover and humidity on the retrievals of AOT from ground-based Cimel sunphotometer measurements, in order to help us sort out the real influence and artifact. In general, it is very difficult to verify and quantify the effects of cloud on satellite retrieval of aerosol quantities. Speculation and warning of cloud contamination have been made whenever there is a correlation between the retrieved AOT and cloud fraction or their spatial variabilities, while it has also been argued that aerosol humidification effect (AHE) might be at work. The ample measurements available from ARM over the SGP region may allow us to unravel this complex issue. Our ultimate goals are to (1) evaluate various effects on the

  15. The Beijing Olympics as a Field Experiment - The Aerosol Footprint of a Megacity

    NASA Astrophysics Data System (ADS)

    Cermak, J.; Knutti, R.

    2009-04-01

    During the 2008 Olympic Summer Games, emission reductions were enforced in and around Beijing to improve the notoriously poor air quality in the city. In this presentation we explore the effect of these measures on the regional aerosol load. To this end, we compare satellite-retrieved aerosol optical thickness of that period with previous years. In addition to absolute changes we explore the 2008 situation in its meteorological context. Using a neural network approach we predict summer 2008 aerosol based on meteorological conditions. Predicted values are contrasted with observations. A statistically significant reduction of aerosol load is found in Beijing that decreases in magnitude and significance with increasing region size. Locally, the aerosol load (log(AOT)) was about 10-15% below the levels expected for the prevailing meteorological situation. The small size of this effect highlights the importance of regional aerosol transport.

  16. Anomalous change in interfacial tension induced by collapses of AOT microemulsions at heptane/water interface

    NASA Astrophysics Data System (ADS)

    Takahashi, Masahiko; Yui, Hiroharu; Ikezoe, Yasuhiro; Sawada, Tsuguo

    2004-05-01

    Dynamic behavior of water-in-oil microemulsions at the oil/water interface was investigated using the quasi-elastic laser scattering method. We observed an anomalous rebound behavior of interfacial tension γ induced by collapses of microemulsions and adsorptions of AOT molecules at the interface. γ rapidly decreased and reached a minimum value (5.5 mN/m) at about 500 s after the preparation of the interface, and then increased gradually for about 2000 s to the equilibrium value (8.0 mN/m). We considered the mechanism of the rebound behavior in terms of transient change in interfacial thickness induced by the collapses of AOT microemulsions.

  17. Properties of conducting films of electrophoretic concentrates of silver and gold nanoparticles in AOT surfactant

    NASA Astrophysics Data System (ADS)

    Bulavchenko, A. I.; Popovetskiy, P. S.; Maksimovskiy, E. A.

    2013-10-01

    Liquid concentrates of silver and gold nanoparticles with 1-2 M metal concentrations were isolated by electrophoresis in a capacitor-type cell from AOT reverse micellar solutions in n-decane. The electrophoretic concentrates and the starting micellar solutions were characterized by nonaqueous electrophoresis, transmission electron microscopy, photon correlation spectroscopy (dynamic light scattering), and spectrophotometry. The hydrodynamic diameter of silver and gold nanoparticles was 13.2 and 8.6 nm, respectively; the ζ-potential was 70 and 13 mV. The drying of the concentrates on glass and silicon substrates and subsequent treatment with a 30% solution of water in ethanol gave mirror conducting Ag, Au, Ag-Au, and Au/Ag films containing on the average 80% metal and 20 wt % AOT. The film structure, morphology, and composition were studied by scanning electron microscopy (SEM) and energy dispersion analysis (EDX).

  18. Water-AOT-alkylbenzene microemulsions: influence of alkyl chain length on structure and percolation behavior.

    PubMed

    Appel, Markus; Spehr, Tinka Luise; Wipf, Robert; Stühn, Bernd

    2012-06-15

    We study the percolation behavior of the water-in-oil (w/o) droplet phase of AOT (sodium bis[2-ethylhexyl] sulfosuccinate)-based microemulsions with different alkylbenzenes (toluene, ethylbenzene, butylbenzene or octylbenzene) as oil phase. We use microemulsions of varying composition with molar water to surfactant ratios 0≤W≤ 50 and droplet (water plus surfactant) volume fractions 10%≤φ≤50%. Using dielectric spectroscopy, a percolation transition is observed in w/o microemulsions with butylbenzene or octylbenzene. With increasing molecular weight of the alkylbenzene, the percolation temperature T(P) decreases. The structure of the microemulsions is determined by small angle X-ray scattering (SAXS). With increasing molar weight of the alkylbenzene, the stability range of the L(2) droplet phase extends to higher W. The larger amount of solubilizable water can be related to variable oil penetration of the AOT monolayer, which affects the spontaneous curvature of the surfactant shell. PMID:22446149

  19. Determining the hydrodynamic radii of AOT micelles with silver nanoparticles by means of photon correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Bulavchenko, A. I.; Popovetskiy, P. S.

    2012-06-01

    The possibility of determining the sizes of micelles of sodium di(2-ethylhexyl)sulfosuccinate (AOT) with silver nanoparticles in decane against the background of a large excess of empty micelles by means of photon correlation spectroscopy with unimodal analysis of the autocorrelation function is demonstrated. Contributions from all components to the light scattering are estimated by measuring the static (Rayleigh) light scattering and allowing for partial absorption of the laser radiation by silver nanoparticles. Areas of the correct determination of the hydrodynamic radius of the micelles with nanoparticles are determined via unimodal analysis of the autocorrelation function in dependence on the nanoparticle size (10-2 nm) and silver concentration (1-30 mM) at a constant AOT concentration (0.25 mol/L) and aqueous pseudophase content (1 vol %).

  20. Complex permittivity of FeCl3/AOT/CCl4 microemulsions probed by AC impedance spectroscopy.

    PubMed

    Calandra, Pietro; Ruggirello, Angela; Turco Liveri, Vincenzo

    2009-09-01

    The complex permittivity of FeCl(3)/AOT/CCl(4) microemulsions in the 1-10(5) Hz frequency range has been measured by the conventional AC complex impedance technique. Measurements as a function of the volume fraction of the dispersed phase (FeCl(3)+AOT) and temperature at fixed salt-to-AOT molar ratio (R, R = 0.5) show that the entrapment of FeCl(3) clusters significantly enhances the local permittivity of the AOT reverse micelles and the number density of charge carriers resulting from the peculiar state of the confined inorganic salt. An estimate of the apparent static permittivity of the FeCl(3) ionic clusters entrapped in the core of AOT reverse micelles gives the very high and quite surprisingly value of about 237. Moreover, a thorough analysis of conductivity data and of their temperature dependence strongly supports the hypothesis that the charge transport in these systems is mainly sustained by a mechanism of hopping consisting in the continuous jumping of charged species within supra-micellar aggregates of AOT reverse micelles whose aggregation is driven by fluctuating opposite charges on contacting micelles. PMID:19481764

  1. A novel technique for estimating aerosol optical thickness trends using meteorological parameters

    NASA Astrophysics Data System (ADS)

    Emetere, Moses E.; Akinyemi, M. L.; Akin-Ojo, O.

    2016-02-01

    Estimating aerosol optical thickness (AOT) over regions can be tasking if satellite data set over such region is very scanty. Therefore a technique whose application captures real-time events is most appropriate for adequate monitoring of risk indicators. A new technique i.e. arithmetic translation of pictorial model (ATOPM) was developed. The ATOPM deals with the use mathematical expression to compute other meteorological parameters obtained from satellite or ground data set. Six locations within 335 × 230 Km2 area of a selected portion of Nigeria were chosen and analyzed -using the meteorological data set (1999-2012) and MATLAB. The research affirms the use of some parameters (e.g. minimum temperature, cloud cover, relative humidity and rainfall) to estimate the aerosol optical thickness. The objective of the paper was satisfied via the use of other meteorological parameters to estimate AOT when the satellite data set over an area is scanty.

  2. Development of a generalized algorithm of satellite remote sensing using multi-wavelength and multi-pixel information (MWP method) for aerosol properties by satellite-borne imager

    NASA Astrophysics Data System (ADS)

    Hashimoto, M.; Nakajima, T.; Morimoto, S.; Takenaka, H.

    2014-12-01

    We have developed a new satellite remote sensing algorithm to retrieve the aerosol optical characteristics using multi-wavelength and multi-pixel information of satellite imagers (MWP method). In this algorithm, the inversion method is a combination of maximum a posteriori (MAP) method (Rodgers, 2000) and the Phillips-Twomey method (Phillips, 1962; Twomey, 1963) as a smoothing constraint for the state vector. Furthermore, with the progress of computing technique, this method has being combined with the direct radiation transfer calculation numerically solved by each iteration step of the non-linear inverse problem, without using LUT (Look Up Table) with several constraints.Retrieved parameters in our algorithm are aerosol optical properties, such as aerosol optical thickness (AOT) of fine and coarse mode particles, a volume soot fraction in fine mode particles, and ground surface albedo of each observed wavelength. We simultaneously retrieve all the parameters that characterize pixels in each of horizontal sub-domains consisting the target area. Then we successively apply the retrieval method to all the sub-domains in the target area.We conducted numerical tests for the retrieval of aerosol properties and ground surface albedo for GOSAT/CAI imager data to test the algorithm for the land area. The result of the experiment showed that AOTs of fine mode and coarse mode, soot fraction and ground surface albedo are successfully retrieved within expected accuracy. We discuss the accuracy of the algorithm for various land surface types. Then, we applied this algorithm to GOSAT/CAI imager data, and we compared retrieved and surface-observed AOTs at the CAI pixel closest to an AERONET (Aerosol Robotic Network) or SKYNET site in each region. Comparison at several sites in urban area indicated that AOTs retrieved by our method are in agreement with surface-observed AOT within ±0.066.Our future work is to extend the algorithm for analysis of AGEOS-II/GLI and GCOM/C-SGLI data.

  3. Variability of aerosol properties over Eastern Europe observed from ground and satellites in the period from 2003 to 2011

    NASA Astrophysics Data System (ADS)

    Bovchaliuk, A.; Milinevsky, G.; Danylevsky, V.; Goloub, P.; Dubovik, O.; Holdak, A.; Ducos, F.; Sosonkin, M.

    2013-07-01

    The paper presents some results of the study on aerosol variability in the period from 2003 to 2011 over the Eastern Europe region, with latitude ranging from 40° N to 60° N and longitude from 20° E to 50° E. The analysis was based on the POLDER/PARASOL and POLDER-2/ADEOS satellites and AERONET (AErosol RObotic NETwork) ground-based sun photometer observations. The aerosol optical thickness (AOT) of the studied area is characterized by values (referenced to 870 nm wavelength) ranging from 0.05 to 0.2, except for in the period of July-August 2010 with strong forest and peat wildfires when the AOT typical values range from 0.3 to 0.5 according to both retrievals. The analysis of seasonal dynamics of aerosol loading has revealed two AOT high value peaks. The spring peak observed in April-May is the result of solitary transportation of Saharan dust in the atmosphere over Eastern Europe, infrequent agricultural fires, transportation of sea salt aerosols by southern winds to Ukraine and Moldova from the Black and Azov seas. The autumn peak in August-September is associated with forest and peat wildfires, considerable transportation of Saharan dust and the presence of soil dust aerosols due to harvesting activity. The maximum values of AOT are observed in May 2006 (0.1-0.15), April 2009 (0.07-0.15) and August 2010 (0.2-0.5). Furthermore, the study has identified a distinct pattern of anthropogenic aerosols over the industrial areas, especially in central Ukraine and eastern Belarus as well as Moscow region in Russia. The comparison of the AOT derived by standard algorithm POLDER/PARASOL with those recomputed from AERONET inversions for fine mode particles with radius < 0.3 μm was performed over several AERONET sites. The correlation coefficients for the POLDER/AERONET AOT retrieval comparisons are equal: 0.78 for Moscow site, 0.76 - Minsk, 0.86 - Belsk, 0.81 - Moldova (period 2005-2009), 0.93 - Kyiv and 0.63 for Sevastopol sites (2008-2009). The deviations are

  4. Choline acetate enhanced the catalytic performance of Candida rogusa lipase in AOT reverse micelles.

    PubMed

    Xue, Luyan; Zhao, Yin; Yu, Lijie; Sun, Yanwen; Yan, Keqian; Li, Ying; Huang, Xirong; Qu, Yinbo

    2013-05-01

    Choline acetate is an ionic liquid composed of a kosmotropic anion and a chaotropic cation. According to Hofmeister series, a kosmotropic anion and/or a chaotropic cation could stabilize an enzyme, thereby facilitating the retention of the catalytic activity of the enzyme. In this work, we first report the influence of choline acetate on the activity and stability of lipase in AOT/water/isooctane reverse micelles. The indicator reaction is the lipase-catalyzed hydrolysis of 4-nitrophenyl butyrate. The results show that a low level of choline acetate does not affect the microstructure of the AOT reverse micelles, but the ionic liquid can improve the catalytic efficiency of lipase. Fluorescence spectra show that a high level of choline acetate has an impact on the conformation of lipase, so the activation is mainly due to the influence of choline acetate on the nucleophilicity of water. Infrared spectra demonstrate that choline acetate can form stronger hydrogen bonds with water surrounding lipase, and therefore enhance the nucleophilicity of the water, which makes it easier to attack the acyl enzyme intermediate, thereby increasing the activity of the lipase-catalyzed hydrolysis of the ester. A study on the stability of lipase in AOT reverse micelles indicates that the ionic liquid is able to maintain the activity of lipase to a certain extent. The effect of choline acetate is consistent with that predicted based on Hofmeister series. PMID:23352950

  5. Molecular dynamics simulations of cytochrome c unfolding in AOT reverse micelles: The first steps.

    PubMed

    Abel, S; Waks, M; Marchi, M

    2010-08-01

    This paper explores the reduced form of horse cytochrome c confined in reverse micelles (RM) of sodium bis-(2-ethylhexyl) sulfosuccinate (AOT) in isooctane by molecular dynamics simulation. RMs of two sizes were constructed at a water content of W (o) = [ H₂O ]/[AOT] = 5.5 and 9.1. Our results show that the protein secondary structure and the heme conformation both depend on micellar hydration. At low hydration, the protein structure and the heme moiety remain stable, whereas at high water content the protein becomes unstable and starts to unfold. At W (o) = 9.1 , according to the X-ray structure, conformational changes are mainly localized on protein loops and around the heme moiety, where we observe a partial opening of the heme crevice. These findings suggest that within our time window (10ns), the structural changes observed at the heme level are the first steps of the protein denaturation process, previously described experimentally in micellar solutions. In addition, a specific binding of AOT molecules to a few lysine residues of the protein was found only in the small-sized RM. PMID:20803162

  6. Cytarabine-AOT catanionic vesicle-loaded biodegradable thermosensitive hydrogel as an efficient cytarabine delivery system.

    PubMed

    Liu, Jing; Jiang, Yue; Cui, Yuting; Xu, Chuanshan; Ji, Xiaoqing; Luan, Yuxia

    2014-10-01

    Carrier with high drug loading content is one of the most important issues in drug delivery system. In the present work, an ion-pair amphiphilic molecule composed of anticancer drug cation and surfactant anion is used for straightforward fabricating vesicles for cancer therapy. Anticancer drug (cytarabine hydrochloride) and anionic surfactant (AOT) are selected for the fabrication of ion-pair amphiphilic molecule. One amphiphilic molecule contains one drug cation, thus the drug loading content is 50% (mol/mol) in theory. The in vitro drug release study shows that the release time of cytarabine is about 3 times of the pure cytarabine solution and the permeability of cytarabine has been improved about 160 times tested by parallel artificial membrane permeability assay model. However, the hemolytic toxicity is largely decreased in the studied concentration range. The in vitro cytotoxicity results show that cytarabine-AOT amphiphiles have a much lower IC50 (drug concentration resulting in 50% cell death) value and a higher cell inhibition rate comparing with their respective components, indicating its effective therapy for leukemic cells. To obtain a longer and a convenient drug release system, the prepared vesicles are further incorporated into the thermosensitive PLGA-PEG-PLGA hydrogel to prepare a subcutaneous administration. The in vivo drug release results indicate that cytarabine-AOT vesicle-loaded hydrogel is a good injectable delivery system for controlled release of cytarabine for cancer therapy. PMID:25066076

  7. Validation of the on-line aerosol retrieval and error characterization algorithm from the OMI Near-UV observations during the DRAGON-NE Asia 2012 campaign

    NASA Astrophysics Data System (ADS)

    Jeong, U.; Ahn, C.; Kim, J.; Bhartia, P. K.; Torres, O.; Spurr, R. J. D.; Liu, X.; Chance, K.; Holben, B. N.

    2014-12-01

    One of the representative advantages of using ultraviolet channel to retrieve aerosol optical property is that the results are less affected by the uncertainty of surface reflectance database. The retrieved aerosol products have relatively uniform quality at both land and ocean except the ice-snow surface. The near UV technique of aerosol remote sensing has additional merit that it has long period database since TOMS (Total Ozone Mapping Spectrometer) including aerosol absorption properties. Thus the retrieved product using the near UV technique using TOMS and OMI (Ozone Monitoring Instrument) measurement is quite appropriate for climatological research. For such purposes, assessment of accuracy of the retrieved product is essential to evaluate the radiative forcing of the aerosols. In this study, the error characterizations of the near UV technique using OMI measurements have been performed with the optimal estimation method during the DRAGON-NE Asia 2012 campaign. In order to avoid the interpolation error, we developed the on-line retrieval scheme based on the traditional near UV method. The retrieval noise and smoothing error of retrieved AOT (Aerosol Optical Thickness) were compared with the biases between 380 nm AOT from AERONET and retrieved 388 nm AOT. They showed positive correlations which infer the possibility of the estimated errors using the optimal estimation method to be used to evaluate the error of retrieved products. Forward model parameter errors were analyzed separately which depends on the quality of the used database, thus can be reduced by improving the database.

  8. A reliable and reproducible method for the lipase assay in an AOT/isooctane reversed micellar system: modification of the copper-soap colorimetric method.

    PubMed

    Kwon, Chang Woo; Park, Kyung-Min; Choi, Seung Jun; Chang, Pahn-Shick

    2015-09-01

    The copper-soap method, which is based on the absorbance of a fatty acid-copper complex at 715 nm, is a widely used colorimetric assay to determine the lipase activity in reversed micellar system. However, the absorbance of the bis(2-ethylhexyl) sodium sulfosuccinate (AOT)-copper complex prevents the use of an AOT/isooctane reversed micellar system. An extraction step was added to the original procedure to remove AOT and eliminate interference from the AOT-copper complex. Among the solvents tested, acetonitrile was determined to be the most suitable because it allows for the generation of a reproducible calibration curve with oleic acid that is independent of the AOT concentrations. Based on the validation data, the modified method, which does not experience interference from the AOT-copper complex, could be a useful method with enhanced accuracy and reproducibility for the lipase assay. PMID:25842332

  9. Atomic force microscopy combined with optical tweezers (AFM/OT)

    NASA Astrophysics Data System (ADS)

    Pierini, F.; Zembrzycki, K.; Nakielski, P.; Pawłowska, S.; Kowalewski, T. A.

    2016-02-01

    The role of mechanical properties is essential to understand molecular, biological materials, and nanostructures dynamics and interaction processes. Atomic force microscopy (AFM) is the most commonly used method of direct force evaluation, but due to its technical limitations this single probe technique is unable to detect forces with femtonewton resolution. In this paper we present the development of a combined atomic force microscopy and optical tweezers (AFM/OT) instrument. The focused laser beam, on which optical tweezers are based, provides us with the ability to manipulate small dielectric objects and to use it as a high spatial and temporal resolution displacement and force sensor in the same AFM scanning zone. We demonstrate the possibility to develop a combined instrument with high potential in nanomechanics, molecules manipulation and biological studies. AFM/OT equipment is described and characterized by studying the ability to trap dielectric objects and quantifying the detectable and applicable forces. Finally, optical tweezers calibration methods and instrument applications are given.

  10. Trends in the aerosol load properties over south eastern Italy

    NASA Astrophysics Data System (ADS)

    Orza, J. A. G.; Perrone, M. R.

    2015-12-01

    The long-term (2003-2013) variations in columnar aerosol properties at Lecce, a site representative of the central Mediterranean, have been analysed for trend assessment. The study focuses on aerosol optical thickness (AOT) at 340, 440, 500 and 1020 nm and Ångström exponent (AE) for the pair 440-870 nm, retrieved from a sun photometer operating within the Aerosol Robotic Network (AERONET). A non-parametric trend analysis of the monthly mean, median and upper and lower tails (90th and 10th percentiles) suggests that the aerosol load has decreased during the study period, while the mean particle size remained unchanged. The characteristic advections reaching the study site were found by clustering analysis of back trajectories at 500, 1500 and 3000 m. Despite the strong influence they have on aerosol load and particle size, neither of the trends in advection routes could explain the tendencies found in the columnar aerosol properties. However, trends in aerosol data by advection type allow understanding the overall trends. Aerosol properties under flows with high residence time over continental Europe present differences according to the specific residing area. More specifically, no trend is found when flows arrive from Ukraine and the Balkans, while under advections from north-western/central Europe there are downward trends in the background levels and a reduction of the fine fraction. Negative trends are also found under flows with high residence time over the Mediterranean and northern Africa, again with differences according to the residing area.

  11. Reduction of Aerosol Absorption in Beijing Since 2007 from MODIS and AERONET

    NASA Technical Reports Server (NTRS)

    Lyapustin, A.; Smirnov, A.; Holben, B.; Chin, M.; Streets, D. G.; Lu, Z.; Kahn, R.; Slutsker, I.; Laszlo, I.; Kondragunta, S.; Tanre, D.; Dubovik, O.; Goloub, P.; Chen, H.-B.; Sinyuk, A.; Wang, Y.; Korkin, S.

    2011-01-01

    An analysis of the time series of MODIS-based and AERONET aerosol records over Beijing reveals two distinct periods, before and after 2007. The MODIS data from both the Terra and Aqua satellites were processed with the new Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm. A comparison of MAIAC and AERONET AOT shows that whereas MAIAC consistently underestimated peak AOT values by 10-20% in the prior period, the bias mostly disappears after mid-2007. Independent analysis of the AERONET dataset reveals little or no change in the effective radii of the fine and coarse fractions and of the Angstrom exponent. At the same time, it shows an increasing trend in the single scattering albedo, by approx.0.02 in 9 years. As MAIAC was using the same aerosol model for the entire 2000-2010 period, the decrease in AOT bias after 2007 can be explained only by a corresponding decrease of aerosol absorption caused by a reduction in local black carbon emissions. The observed changes correlate in time with the Chinese government's broad measures to improve air quality in Beijing during preparations for the Summer Olympics of 2008.

  12. Reduction of Aerosol Absorption in Beijing Since 2007 from MODIS and AERONET

    NASA Technical Reports Server (NTRS)

    Lyapustin, A.; Smirnov, A.; Holben, B.; Chin, M.; Streets, D. G.; Lu, Z.; Kahn, R.; Slutsker, I.; Laszlo, I.; Kondragunta, S.; Tanre, D.; Dubovik, O.; Goloub, P.; Chen, H.-B.; Sinyuk, A.; Wang, Y.; Korkin, S.

    2011-01-01

    An analysis of the time series of MODIS-based and AERONET aerosol records over Beijing reveals two distinct periods, before and after 2007. The MODIS data from both the Terra and Aqua satellites were processed with the new Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm. A comparison of MAIAC and AERONET AOT shows that whereas MAIAC consistently underestimated peak AOT values by 10-20% in the prior period, the bias mostly disappears after mid- 2007. Independent analysis of the AERONET dataset reveals little or no change in the effective radii of the fine and coarse fractions and of the Angstrom exponent. At the same time, it shows an increasing trend in the single scattering albedo, by 0.02 in 9 years. As MAIAC was using the same aerosol model for the entire 2000-2010 period, the decrease in AOT bias after 2007 can be explained only by a corresponding decrease of aerosol absorption caused by a reduction in local black carbon emissions. The observed changes correlate in time with the Chinese government's broad measures to improve air quality in Beijing during preparations for the Summer Olympics of 2008.

  13. Reduction of aerosol absorption in Beijing since 2007 from MODIS and AERONET

    NASA Astrophysics Data System (ADS)

    Lyapustin, A.; Smirnov, A.; Holben, B.; Chin, M.; Streets, D. G.; Lu, Z.; Kahn, R.; Slutsker, I.; Laszlo, I.; Kondragunta, S.; Tanré, D.; Dubovik, O.; Goloub, P.; Chen, H.-B.; Sinyuk, A.; Wang, Y.; Korkin, S.

    2011-05-01

    An analysis of the time series of MODIS-based and AERONET aerosol records over Beijing reveals two distinct periods, before and after 2007. The MODIS data from both the Terra and Aqua satellites were processed with the new Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm. A comparison of MAIAC and AERONET AOT shows that whereas MAIAC consistently underestimated peak AOT values by 10-20% in the prior period, the bias mostly disappears after mid-2007. Independent analysis of the AERONET dataset reveals little or no change in the effective radii of the fine and coarse fractions and of the Ångström exponent. At the same time, it shows an increasing trend in the single scattering albedo, by ˜0.02 in 9 years. As MAIAC was using the same aerosol model for the entire 2000-2010 period, the decrease in AOT bias after 2007 can be explained only by a corresponding decrease of aerosol absorption caused by a reduction in local black carbon emissions. The observed changes correlate in time with the Chinese government's broad measures to improve air quality in Beijing during preparations for the Summer Olympics of 2008.

  14. Distinct impact of different types of aerosols on surface solar radiation in China

    NASA Astrophysics Data System (ADS)

    Yang, Xin; Zhao, Chuanfeng; Zhou, Lijing; Wang, Yang; Liu, Xiaohong

    2016-06-01

    Observations of surface direct solar radiation (DSR) and visibility, particulate matter with aerodynamic diameters less than 2.5 µm (PM2.5), together with the aerosol optical thickness (AOT) taken from Moderate-Resolution Imaging Spectroradiometer and Multiangle Imaging Spectroradiometer, were investigated to gain insight into the impact of aerosol pollution on surface solar radiation in China. The surface DSR decreased during 2004-2014 compared with 1993~2003 over eastern China, but no clear reduction was observed in remote regions with cleaner air. Significant correlations of visibility, PM2.5, and regionally averaged AOT with the surface DSR over eastern China indicate that aerosol pollution greatly affects the energy available at the surface. The net loss of surface solar radiation also reduces the surface ground temperature over eastern China. However, the slope of the linear variation of the radiation with respect to atmospheric visibility is distinctly different at different stations, implying that the main aerosol type varies regionally. The largest slope value occurs at Zhengzhou and indicates that the aerosol absorption in central China is the highest, and lower slope values suggest relatively weakly absorbing types of aerosols at other locations. The spatial distribution of the linear slopes agrees well with the geographical distribution of the absorbing aerosols derived from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations and Ozone Monitoring Instrument over China. The regional correlation between a larger slope value and higher absorbance properties of aerosols indicates that the net effects of aerosols on the surface solar energy and corresponding climatic effects are dependent on both aerosol amount and optical properties.

  15. Optimization of OT-MACH Filter Generation for Target Recognition

    NASA Technical Reports Server (NTRS)

    Johnson, Oliver C.; Edens, Weston; Lu, Thomas T.; Chao, Tien-Hsin

    2009-01-01

    An automatic Optimum Trade-off Maximum Average Correlation Height (OT-MACH) filter generator for use in a gray-scale optical correlator (GOC) has been developed for improved target detection at JPL. While the OT-MACH filter has been shown to be an optimal filter for target detection, actually solving for the optimum is too computationally intensive for multiple targets. Instead, an adaptive step gradient descent method was tested to iteratively optimize the three OT-MACH parameters, alpha, beta, and gamma. The feedback for the gradient descent method was a composite of the performance measures, correlation peak height and peak to side lobe ratio. The automated method generated and tested multiple filters in order to approach the optimal filter quicker and more reliably than the current manual method. Initial usage and testing has shown preliminary success at finding an approximation of the optimal filter, in terms of alpha, beta, gamma values. This corresponded to a substantial improvement in detection performance where the true positive rate increased for the same average false positives per image.

  16. Hemispheric asymmetry in aerosol optical thickness and cloud fraction over the tropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Kishcha, Pavel; Starobinets, Boris; da Silva, Arlindo; Long, Charles; Kalashnikova, Olga; Alpert, Pinhas

    2015-04-01

    Hemispheric asymmetry in cloud fraction and aerosols could lead to hemispheric imbalance in solar radiation reaching the surface and, consequently, could affect the Earth radiation budget. Previous studies showed that, over the global ocean, there is no noticeable hemispheric asymmetry in cloud fraction (CF). This contributes to the balance in solar radiation reaching the sea surface in the Northern and Southern hemispheres. In the current study, we focus on the tropical Atlantic (30oN - 30oS) which is characterized by significant amounts of Saharan dust dominating other aerosol species over the North Atlantic. Our main point is that, over the tropical Atlantic, not only is Saharan dust responsible for the pronounced hemispheric aerosol asymmetry, but it also contributes to significant cloud cover along the Saharan Air Layer. This could lead to the hemispheric imbalance in strong solar radiation reaching the sea surface in the tropical Atlantic. During the 10-year study period (July 2002 - June 2012), NASA Aerosol Reanalysis (aka MERRAero) showed that, when the hemispheric asymmetry in dust aerosol optical thickness (AOT) was the most pronounced (particularly in July), dust AOT averaged separately over the tropical North Atlantic was one order of magnitude higher than that averaged over the tropical South Atlantic. In the presence of such strong hemispheric asymmetry in dust AOT in July, CF averaged separately over the tropical North Atlantic exceeded that over the tropical South Atlantic by 20%. In July, along the Saharan Air Layer, Moderate Resolution Imaging Spectroradiometer (MODIS) CF data showed significant cloud cover (up to 0.8 - 0.9). This significant cloud fraction along SAL together with clouds over the Atlantic Inter-tropical Convergence Zone contributes to the above-mentioned hemispheric CF asymmetry. Both Multi-Angle Imaging SpectroRadiometer (MISR) measurements and MERRAero data were in agreement on seasonal variations in hemispheric aerosol

  17. A new organized media: glycerol:N,N-dimethylformamide mixtures/AOT/n-heptane reversed micelles. The effect of confinement on preferential solvation.

    PubMed

    Durantini, Andrés M; Falcone, R Dario; Silber, Juana J; Correa, N Mariano

    2011-05-19

    In this work we investigate the behavior of the glycerol (GY):N,N-dimethylformamide (DMF) mixture in homogeneous and sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane reversed micelles (RMs) media. To achieve this goal we have used the solvatochromic behavior of 1-methyl-8-oxyquinolinium betaine (QB) as an absorption probe, and dynamic light scattering (DLS). QB shows strong preferential solvation when it is dissolved in the GY:DMF mixture, and, as QB is a good hydrogen bond acceptor molecular probe, it is preferentially solvated by the GY-DMF hydrogen-bonded (H-bonded) species. On the other hand, when the GY:DMF mixture was investigated in AOT RMs, the results show that the mixture is encapsulated in the polar core of the AOT RMs. DLS confirms the formation of the GY:DMF/AOT/n-heptane RMs since an increase in the W(s)=([GY]+[DMF])/[AOT] values causes an increment in the RMs droplets sizes. The solvatochromic behavior of QB, which resides at the AOT RMs interface, shows that QB is mostly solvated by GY molecules, especially at low W(s) values. Thus, it seems that upon encapsulation inside the polar core of the AOT RMs, the GY-DMF interaction diminishes due to the strong AOT-GY interaction. (1)H NMR chemical shifts of GY and DMF measured in the different AOT RMs investigated shows that GY and DMF behave practically as noninteracting solvents inside the RMs. PMID:21517031

  18. Daily estimates of aerosol optical thickness over land surface based on a directional and temporal analysis of SEVIRI MSG visible observations

    NASA Astrophysics Data System (ADS)

    Carrer, Dominique; Roujean, Jean-Louis; Hautecoeur, Olivier; Elias, Thierry

    2010-05-01

    This paper presents an innovative method for obtaining a daily estimate of a quality-controlled aerosol optical thickness (AOT) of a vertical column of the atmosphere over the continents. Because properties of land surface are more stationary than the atmosphere, the temporal dimension is exploited for simultaneous retrieval of the surface and aerosol bidirectional reflectance distribution function (BRDF) coming from a kernel-driven reflectance model. Off-zenith geometry of illumination enhances the forward scattering peak of the aerosol, which improves the retrieval of AOT from the aerosol BRDF. The solution is obtained through an unconstrained linear inversion procedure and perpetuated in time using a Kalman filter. On the basis of numerical experiments using the 6S atmospheric code, the validity of the BRDF model is demonstrated. The application is carried out with data from the Spinning Enhanced Visible and Infra Red Imager (SEVIRI) instrument on board the geostationary Meteosat Second Generation (MSG) satellite from June 2005 to August 2007 for midlatitude regions and from March 2006 to June 2006 over desert sites. The satellite-derived SEVIRI AOT compares favorably with Aerosol Robotic Network (AERONET) measurements for a number of contrasted stations and also similar Moderate Resolution Imaging Spectroradiometer (MODIS) products, within 20% of relative accuracy. The method appears competitive for tracking anthropogenic aerosol emissions in the troposphere and shows a potential for the challenging estimate of dust events over bright targets. Moreover, a high-frequency distribution of AOT provides hints as to the variability of pollutants according to town density and, potentially, motor vehicle traffic. The outcomes of the present study are expected to promote a monitoring of the global distributions of natural and anthropogenic sources and sinks of aerosol, which are receiving increased attention because of their climatic implications.

  19. A study of aerosol optical properties at the global GAW station Bukit Kototabang, Sumatra, Indonesia

    NASA Astrophysics Data System (ADS)

    Nurhayati, N.; Nakajima, Teruyuki

    2012-01-01

    There have been very few studies carried out in Indonesia on the atmospheric aerosol optical properties and their impact on the earth climate. This study utilized solar radiation and aerosol measurement results of Indonesian GAW station Bukit Kototabang in Sumatra. The radiation data of nine years were used as input to a radiation simulation code for retrieving optically equivalent parameters of aerosols, i.e., aerosol optical thickness (AOT), coarse particle to fine particle ratio ( γ-ratio), and soot fraction. Retrieval of aerosol properties shows that coarse particles dominated at the station due to high relative humidity (RH) reaching more than 80% throughout the year. AOT time series showed a distinct two peak structure with peaks in MJJ and NDJ periods. The second peak corresponds to the period of high RH suggesting it was formed by active particle growth with large RH near 90%. On the other hand the time series of hot spot number, though it is only for the year of 2004, suggests the first peak was strongly contributed by biomass burning aerosols. The γ-ratio took a value near 10 throughout the year except for November and December when it took a larger value. The soot fraction varies in close relation with the γ-ratio, i.e. low values when γ was large, as consistent with our proposal of active particle growth in the high relative periods.

  20. Fixed ground antenna radome (FGAR) type 1/3 OT&E integrations and OT&E operational

    NASA Astrophysics Data System (ADS)

    Baker, Leonard H.; Sedgwick, Harold G.

    1995-05-01

    This test report documents the Operational Test and Evaluation (OT&E) Integration and OT&E Operational testing performed on the Type I/Ill, Fixed Ground Antenna Radome (FGAR). The Type I/Ill FGAR is used with the Air Route Surveillance Radar (ARSR)) -1/2 and AN/FPS military radars. The testing was performed at the Federal Aviation Administration (FAA) Technical Center's Elwood En Route Beacon Test Facility (ERBTF) and the Northwest Mountain Region's Trinidad En Route Radar Facility (TAD), Colorado. The testing included: (1) characterization of the primary and secondary radar's electromagnetic performance; (2) human factors; (3) physical characteristics; and (4) physical performance. The electromagnetic performance testing showed no degradation of the primary or secondary radars; there were no human factor problems found; and only minor problems were identified during the physical characteristics and physical performance tests. The testing determined that the FGAR meets the Operational Suitability and Operational Effectiveness requirements of the FAA.

  1. Aerosol Optical Thickness Variability in the New York Metropolitan Area

    NASA Astrophysics Data System (ADS)

    Liepert, B. G.

    2003-12-01

    In July 2003 this field study was performed as part of the NASA Goddard Institute for Space Studies Summer Program "Institute for Climate and Planets". The spatial variability of aerosol spectral optical thickness (AOT) in the New York Metropolitan area was measured with a hand held sun photometer "Microtops II". Measurements were taken on board of a cruise ship around Manhattan, and several transects from North to South and East to West within New York City including on top of the Empire State Building. These data are compared to other available ground observations of urban aerosols and to satellite data from MODIS. Consequences of the spatial variability of the effect of urban aerosols on climate will be discussed.

  2. Regulation of functional KCNQ1OT1 lncRNA by β-catenin

    PubMed Central

    Sunamura, Naohiro; Ohira, Takahito; Kataoka, Miki; Inaoka, Daigo; Tanabe, Hideyuki; Nakayama, Yuji; Oshimura, Mitsuo; Kugoh, Hiroyuki

    2016-01-01

    Long noncoding RNAs (lncRNAs) have been implicated in many biological processes through epigenetic mechanisms. We previously reported that KCNQ1OT1, an imprinted antisense lncRNA in the human KCNQ1 locus on chromosome 11p15.5, is involved in cis-limited silencing within an imprinted KCNQ1 cluster. Furthermore, aberration of KCNQ1OT1 transcription was observed with a high frequency in colorectal cancers. However, the molecular mechanism of the transcriptional regulation and the functional role of KCNQ1OT1 in colorectal cancer remain unclear. Here, we show that the KCNQ1OT1 transcriptional level was significantly increased in human colorectal cancer cells in which β-catenin was excessively accumulated in the nucleus. Additionally, overexpression of β-catenin resulted in an increase in KCNQ1OT1 lncRNA-coated territory. On the other hand, knockdown of β-catenin resulted in significant decrease of KCNQ1OT1 lncRNA-coated territory and an increase in the mRNA expression of the SLC22A18 and PHLDA2 genes that are regulated by KCNQ1OT1. We showed that β-catenin can promote KCNQ1OT1 transcription through direct binding to the KCNQ1OT1 promoter. Our evidence indicates that β-catenin signaling may contribute to development of colorectal cancer by functioning as a novel lncRNA regulatory factor via direct targeting of KCNQ1OT1. PMID:26868975

  3. Characterizing the Spatial and Temporal Distribution of Aerosol Optical Thickness Over the Atlantic Basin Utilizing GOES-8 Multispectral Data

    NASA Technical Reports Server (NTRS)

    Fox, Robert; Prins, Elaine Mae; Feltz, Joleen M.

    2001-01-01

    In recent years, modeling and analysis efforts have suggested that the direct and indirect radiative effects of both anthropogenic and natural aerosols play a major role in the radiative balance of the earth and are an important factor in climate change calculations. The direct effects of aerosols on radiation and indirect effects on cloud properties are not well understood at this time. In order to improve the characterization of aerosols within climate models it is important to accurately parameterize aerosol forcing mechanisms at the local, regional, and global scales. This includes gaining information on the spatial and temporal distribution of aerosols, transport regimes and mechanisms, aerosol optical thickness, and size distributions. Although there is an expanding global network of ground measurements of aerosol optical thickness and size distribution at specific locations, satellite data must be utilized to characterize the spatial and temporal extent of aerosols and transport regimes on regional and global scales. This study was part of a collaborative effort to characterize aerosol radiative forcing over the Atlantic basin associated with the following three major aerosol components in this region: urban/sulfate, Saharan dust, and biomass burning. In-situ ground measurements obtained by a network of sun photometers during the Smoke Clouds and Radiation Experiment in Brazil (SCAR-B) and the Tropospheric Aerosol Radiative Forcing Observational Experiment (TARFOX) were utilized to develop, calibrate, and validate a Geostationary Operational Environmental Satellite (GOES)-8 aerosol optical thickness (AOT) product. Regional implementation of the GOES-8 AOT product was used to augment point source measurements to gain a better understanding of the spatial and temporal distributions of Atlantic basin aerosols during SCAR-B and TARFOX.

  4. Aerosol optical thickness over the Mediterranean region by Modis (Terra): 2001 climatology and validation

    NASA Astrophysics Data System (ADS)

    Barnaba, F.; Gobbi, G. P.

    2003-04-01

    Atmospheric suspended matter (aerosol) strongly impact the Earth radiative budget by scattering and absorbing solar and terrestrial radiation. At a given wavelength, the main parameter commonly used to define their capability to extinguish radiation is the aerosol optical thickness (AOT). Monitoring such a quantity from space is fundamental to assess both global and regional impact of atmospheric aerosols. At the same time, these observations need to be compared to and integrated with ground-based measurements. One-year (2001) AOT data at 550 nm from the MODerate resolution Imaging Spectroradiometer (MODIS, on board of the NASA-Terra spacecraft) have been analyzed for the Mediterranean region, with particular focus on the Italian peninsula. Retrieved over both land and ocean, these data show interesting features of aerosol geographical and seasonal distribution. An evaluation of the MODIS aerosol retrieval over land has been performed comparing satellite-derived data with coincidental ground-based photometric AOT measurements at three different Italian sites (Rome - Tor Vergata, Ispra and Oristano as part of the AErosol RObotic NETwork, AERONET). For the Rome - Tor Vergata site, the availability of coincidental ground-based lidar measurements allowed to further investigate the MODIS retrieval by distinguishing between different atmospheric conditions. This analysis shows the different atmospheric regimes to have a not-negligible impact on the satellite retrieval. For the Oristano coastal site a comparison between land and ocean retrievals has been possible. In this case, the (expected) better performance of the ocean retrieval mainly translates in the reduction of the bias observed between MODIS and photometer measurements.

  5. A synthesis of AOT40-based response functions and critical levels of ozone for agricultural and horticultural crops

    NASA Astrophysics Data System (ADS)

    Mills, G.; Buse, A.; Gimeno, B.; Bermejo, V.; Holland, M.; Emberson, L.; Pleijel, H.

    Crop-response data from over 700 published papers and conference proceedings have been analysed with the aim of establishing ozone dose-response functions for a wide range of European agricultural and horticultural crops. Data that met rigorous selection criteria (e.g. field-based, ozone concentrations within European range, full season exposure period) were used to derive AOT40-yield response functions for 19 crops by first converting the published ozone concentration data into AOT40 (AOT40 is the hourly mean ozone concentration accumulated over a threshold ozone concentration of 40 ppb during daylight hours, units ppm h). For any individual crop, there were no significant differences in the linear response functions derived for experiments conducted in the USA or Europe, or for individual cultivars. Three statistically independent groups were identified: ozone sensitive crops (wheat, water melon, pulses, cotton, turnip, tomato, onion, soybean and lettuce); moderately sensitive crops (sugar beet, potato, oilseed rape, tobacco, rice, maize, grape and broccoli) and ozone resistant (barley and fruit represented by plum and strawberry). Critical levels of a 3 month AOT40 of 3 ppm h and a 3.5 month AOT40 of 6 ppm h were derived from the functions for wheat and tomato, respectively.

  6. Investigation on the conformations of AOT in water-in-oil microemulsions using 2D-ATR-FTIR correlation spectroscopy

    NASA Astrophysics Data System (ADS)

    Lai, Zuliang; Wu, Peiyi

    2008-07-01

    The carbonyl groups of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in the water-in-oil (W/O) microemulsions of AOT/tetrachloromethane/water were investigated by using two-dimensional attenuated total reflection Fourier transform infrared (2D-ATR-FTIR) correlation spectroscopy under a perturbation of temperature. The results of a traditional curve fitting method were compared with the 2D correlation spectra results. The peaks at 1718 and 1736 cm -1 were assigned to different carbonyl groups in trans conformation and gauche conformation of AOT molecules, respectively. With the increase of temperature, the trans conformation increased quickly at the lower temperature below 35 °C and decreased slowly at the higher temperature. The special phenomenon owed to the composition and decomposition of the hydrogen bonding between water of the inner polar core and carbonyl groups of AOT molecules. Two new peaks at 1707 and 1747 cm -1 in the 2D correlation spectra implied the process of the transition of AOT molecule conformation and the deviation of correlation coefficients of curve fitting method. 2D-ATR-FTIR correlation spectroscopy exhibited the superiority over the traditional curve fitting method.

  7. Validation of Long-Term Global Aerosol Climatology Project Optical Thickness Retrievals Using AERONET and MODIS Data

    NASA Technical Reports Server (NTRS)

    Geogdzhayev, Igor V.; Mishchenko, Michael I.

    2015-01-01

    A comprehensive set of monthly mean aerosol optical thickness (AOT) data from coastal and island AErosol RObotic NETwork (AERONET) stations is used to evaluate Global Aerosol Climatology Project (GACP) retrievals for the period 1995-2009 during which contemporaneous GACP and AERONET data were available. To put the GACP performance in broader perspective, we also compare AERONET and MODerate resolution Imaging Spectroradiometer (MODIS) Aqua level-2 data for 2003-2009 using the same methodology. We find that a large mismatch in geographic coverage exists between the satellite and ground-based datasets, with very limited AERONET coverage of open-ocean areas. This is especially true of GACP because of the smaller number of AERONET stations at the early stages of the network development. Monthly mean AOTs from the two over-the-ocean satellite datasets are well-correlated with the ground-based values, the correlation coefficients being 0.81-0.85 for GACP and 0.74-0.79 for MODIS. Regression analyses demonstrate that the GACP mean AOTs are approximately 17%-27% lower than the AERONET values on average, while the MODIS mean AOTs are 5%-25% higher. The regression coefficients are highly dependent on the weighting assumptions (e.g., on the measure of aerosol variability) as well as on the set of AERONET stations used for comparison. Comparison of over-the-land and over-the-ocean MODIS monthly mean AOTs in the vicinity of coastal AERONET stations reveals a significant bias. This may indicate that aerosol amounts in coastal locations can differ significantly from those in adjacent open-ocean areas. Furthermore, the color of coastal waters and peculiarities of coastline meteorological conditions may introduce biases in the GACP AOT retrievals. We conclude that the GACP and MODIS over-the-ocean retrieval algorithms show similar ranges of discrepancy when compared to available coastal and island AERONET stations. The factors mentioned above may limit the performance of the

  8. Organic aerosols

    SciTech Connect

    Penner, J.E.

    1994-01-01

    Organic aerosols scatter solar radiation. They may also either enhance or decrease concentrations of cloud condensation nuclei. This paper summarizes observed concentrations of aerosols in remote continental and marine locations and provides estimates for the sources of organic aerosol matter. The anthropogenic sources of organic aerosols may be as large as the anthropogenic sources of sulfate aerosols, implying a similar magnitude of direct forcing of climate. The source estimates are highly uncertain and subject to revision in the future. A slow secondary source of organic aerosols of unknown origin may contribute to the observed oceanic concentrations. The role of organic aerosols acting as cloud condensation nuclei (CCN) is described and it is concluded that they may either enhance or decrease the ability of anthropogenic sulfate aerosols to act as CCN.

  9. Impact of aerosols on the OMI tropospheric NO2 retrievals over industrialized regions: how accurate is the aerosol correction of cloud-free scenes via a simple cloud model?

    NASA Astrophysics Data System (ADS)

    Chimot, J.; Vlemmix, T.; Veefkind, J. P.; de Haan, J. F.; Levelt, P. F.

    2015-08-01

    The Ozone Monitoring Instrument (OMI) instrument has provided daily global measurements of tropospheric NO2 for more than a decade. Numerous studies have drawn attention to the complexities related to measurements of tropospheric NO2 in the presence of aerosols. Fine particles affect the OMI spectral measurements and the length of the average light path followed by the photons. However, they are not explicitly taken into account in the current OMI tropospheric NO2 retrieval chain. Instead, the operational OMI O2-O2 cloud retrieval algorithm is applied both to cloudy scenes and to cloud free scenes with aerosols present. This paper describes in detail the complex interplay between the spectral effects of aerosols, the OMI O2-O2 cloud retrieval algorithm and the impact on the accuracy of the tropospheric NO2 retrievals through the computed Air Mass Factor (AMF) over cloud-free scenes. Collocated OMI NO2 and MODIS Aqua aerosol products are analysed over East China, in industrialized area. In addition, aerosol effects on the tropospheric NO2 AMF and the retrieval of OMI cloud parameters are simulated. Both the observation-based and the simulation-based approach demonstrate that the retrieved cloud fraction linearly increases with increasing Aerosol Optical Thickness (AOT), but the magnitude of this increase depends on the aerosol properties and surface albedo. This increase is induced by the additional scattering effects of aerosols which enhance the scene brightness. The decreasing effective cloud pressure with increasing AOT represents primarily the absorbing effects of aerosols. The study cases show that the actual aerosol correction based on the implemented OMI cloud model results in biases between -20 and -40 % for the DOMINO tropospheric NO2 product in cases of high aerosol pollution (AOT ≥ 0.6) and elevated particles. On the contrary, when aerosols are relatively close to the surface or mixed with NO2, aerosol correction based on the cloud model results in

  10. New Global Deep Blue Aerosol Product over Land and Ocean from VIIRS, and Its comparisons with MODIS

    NASA Astrophysics Data System (ADS)

    Hsu, N. Y. C.; Bettenhausen, C.; Sayer, A. M.; Lee, J.; Tsay, S. C.; Carletta, N.

    2015-12-01

    The impacts of natural and anthropogenic sources of air pollution on climate and human health have continued to gain attention from the scientific community. In order to facilitate these effects, high quality consistent long-term global aerosol data records from satellites are essential. Several EOS-era instruments (e.g., SeaWiFS, MODIS, and MISR) are able to provide such information with a high degree of fidelity. However, with the aging MODIS sensors and the launch of the VIIRS instrument on Suomi NPP in late 2011, the continuation of long-term aerosol data records suitable for climate studies from MODIS to VIIRS is needed urgently. VIIRS was designed to have similar capabilities to MODIS, with similar visible/infrared spectral channels, and spatial/ temporal resolution. However, small but significant differences in several key channels used in aerosol retrievals between MODIS and VIIRS mean that significant effort is required to revise aerosol models and surface reflectance determination modules previously developed using MODIS data. In this study, we will show the global (land and ocean) distribution of aerosols from Version 1 of the VIIRS Deep Blue data set. The preliminary validation results of these new VIIRS Deep Blue aerosol products using data from AERONET sunphotometers over land and ocean will be discussed. We will also compare the monthly averaged Deep Blue aerosol optical thickness (AOT) from VIIRS with the MODIS C6 products to investigate if any systematic biases may exist between MODIS C6 and VIIRS AOT.

  11. Spinodal decomposition of the three-component microemulsion system: AOT/water/decane

    SciTech Connect

    Mallamace, F.; Micali, N.; Trusso, S.; Chen, S.H.

    1995-12-31

    The authors have performed a series of spinodal decomposition measurements of a three-component microemulsion system made of a surfactant AOT, water, and decane. The measurements were made by a temperature jump from a one-phase droplet microemulsion to a two-phase droplet microemulsion along the critical iso-volume fraction line (10%) using the time resolved light scattering intensity technique. All three stages of the evolution were studied. The typical scattering intensity distribution is in good agreement with recent dynamic scaling theories.

  12. Interdroplet attractive forces in AOT water-in-oil microemulsions formed in subcritical and supercritical solvents

    SciTech Connect

    Tingey, J.M.; Fulton, J.L.; Smith, R.D. )

    1990-03-08

    The van der Waals attractive interactions between aqueous droplets in water-in-oil type microemulsions have been investigated for a range of continuous-phase solvents including the alkanes from methane to isooctane and the noble gases, krypton and xenon. Hamaker constants for water droplets with surfactant shells of the sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in subcritical and supercritical solvents were calculated by using Lifshitz theory and the resulting interaction potential calculations qualitatively account for many features of the phase behavior of these systems.

  13. Effect of proteins on dynamics of water-in-oil AOT microemulsions

    NASA Astrophysics Data System (ADS)

    Hirai, M.; Kawai-Hirai, R.; Iwase, H.; Hayakawa, T.; Kawabata, Y.; Takeda, T.

    By using neutron spin echo and small angle X-ray scattering methods, we studied the effect of the occlusion of proteins on the structure and dynamics of a water-in-oil sodium bis(2-ethylhexyl)sulfosuccinate (AOT) microemulsion with varying protein concentration. We observed a change of the peak height of the effective diffusion coefficient, indicating that the occlusion of proteins enhances a shape fluctuation of the microemulsion. Such an enhancement would be essentially important for an appearance of super-activity of enzymes occluded in microemulsions.

  14. 75 FR 24775 - Open Meeting of the OTS Mutual Savings Association Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-05

    ...The OTS Mutual Savings Associations Advisory Committee (MSAAC) will convene a telephonic meeting on Friday, May 21, 2010, beginning at 2 p.m. Eastern Time. The telephonic meeting will be open to the public. Members of the public interested in listening to the meeting and members of the public who require auxiliary aid should e-mail OTS at mutualcommittee@ots.treas.gov or call (202) 906-6429 to......

  15. Climatology of aerosol properties and clear-sky shortwave radiative effects using Lidar and Sun photometer observations in the Dakar site

    NASA Astrophysics Data System (ADS)

    Mortier, A.; Goloub, P.; Derimian, Y.; Tanré, D.; Podvin, T.; Blarel, L.; Deroo, C.; Marticorena, B.; Diallo, A.; Ndiaye, T.

    2016-06-01

    This paper presents the analysis of nearly a decade of continuous aerosol observations performed at the Mbour site (Senegal) with Sun photometer, Lidar, and Tapered Electromagnetic Oscillating Microbalance. This site is influenced all year-round by desert dust and sporadically, in wintertime, by biomass burning particles. Different patterns are revealed for winter and summer, seasons associated to air masses of different origin. The summer (wet season) is characterized by a high aerosol loading (optical thickness, AOT, around 0.57 at 532 nm) composed of large and weakly absorbing particles (Angstrom exponent, α, of 0.23 and single-scattering albedo, ϖ0, of 0.94 at 532 nm). A lower aerosol loading (AOT = 0.32) is observed during winter (dry season) for finer and absorbing particles (α = 0.48 and ϖ0 = 0.87) revealing the presence of biomass burning aerosols and a greater proportion of local emissions. This latter anthropogenic contribution is visible at weekly and daily scales through AOT cycles. A decrease of about 30% in AOT has been featured in autumn since 2003. The derivation of the extinction profiles highlights a dust transport close to the ground during winter and in an aloft layer (up to 5 km) during summer. Accurate calculations of the daily aerosol radiative effect in clear-sky conditions are finally addressed. From spring to winter, seasonal shortwave radiative forcing averages of 14.15, 11.15, 8.92, and 12.06 W m-2 have been found respectively. Up to 38% of the solar clear-sky atmospheric heating can be attributed to the aerosols in this site.

  16. The ALMA OT in early science: supporting multiple customers

    NASA Astrophysics Data System (ADS)

    Bridger, Alan; Williams, Stewart; McLay, Stewart; Yatagai, Hiroshi; Schilling, Marcus; Biggs, Andrew; Tobar, Rodrigo; Warmels, Rein H.

    2012-09-01

    The ALMA Observatory is currently operating 'Early Science' observing. The Cycle0 and Cycle1 Calls for Proposals are part of this Early Science, and in both the ALMA Observing Tool plays a crucial role. This paper describes how the ALMA OT tackles the problem of making millimeter/sub-millimeter interferometry accessible to the wider community, while allowing "experts" the power and flexibility they need. We will also describe our approach to the challenges of supporting multiple customers, and explore the lessons learnt from the Early Science experiences. Finally we look ahead to the challenges presented by future observing cycles.

  17. Near-Cloud Aerosol Properties from the 1 Km Resolution MODIS Ocean Product

    NASA Technical Reports Server (NTRS)

    Varnai, Tamas; Marshak, Alexander

    2014-01-01

    This study examines aerosol properties in the vicinity of clouds by analyzing high-resolution atmospheric correction parameters provided in the MODIS (Moderate Resolution Imaging Spectroradiometer) ocean color product. The study analyzes data from a 2 week long period of September in 10 years, covering a large area in the northeast Atlantic Ocean. The results indicate that on the one hand, the Quality Assessment (QA) flags of the ocean color product successfully eliminate cloud-related uncertainties in ocean parameters such as chlorophyll content, but on the other hand, using the flags introduces a sampling bias in atmospheric products such as aerosol optical thickness (AOT) and Angstrom exponent. Therefore, researchers need to select QA flags by balancing the risks of increased retrieval uncertainties and sampling biases. Using an optimal set of QA flags, the results reveal substantial increases in optical thickness near clouds-on average the increase is 50% for the roughly half of pixels within 5 km from clouds and is accompanied by a roughly matching increase in particle size. Theoretical simulations show that the 50% increase in 550nm AOT changes instantaneous direct aerosol radiative forcing by up to 8W/m2 and that the radiative impact is significantly larger if observed near-cloud changes are attributed to aerosol particles as opposed to undetected cloud particles. These results underline that accounting for near-cloud areas and understanding the causes of near-cloud particle changes are critical for accurate calculations of direct aerosol radiative forcing.

  18. Aerosol optical properties and precipitable water vapor column in the atmosphere of Norway.

    PubMed

    Muyimbwa, Dennis; Frette, Øyvind; Stamnes, Jakob J; Ssenyonga, Taddeo; Chen, Yi-Chun; Hamre, Børge

    2015-02-20

    Between February 2012 and April 2014, we measured and analyzed direct solar radiances at a ground-based station in Bergen, Norway. We discovered that the spectral aerosol optical thickness (AOT) and precipitable water vapor column (PWVC) retrieved from these measurements have a seasonal variation with highest values in summer and lowest values in winter. The highest value of the monthly median AOT at 440 nm of about 0.16 was measured in July and the lowest of about 0.04 was measured in December. The highest value of the monthly median PWVC of about 2.0 cm was measured in July and the lowest of about 0.4 cm was measured in December. We derived Ångström exponents that were used to deduce aerosol particle size distributions. We found that coarse-mode aerosol particles dominated most of the time during the measurement period, but fine-mode aerosol particles dominated during the winter seasons. The derived Ångström exponent values suggested that aerosols containing sea salt could have been dominating at this station during the measurement period. PMID:25968219

  19. Aerosol Source Plume Physical Characteristics from Space-based Multiangle Imaging

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph A.; Li, W.-H.; Moroney, Catherine; Diner, David J.; Martonchik, John V.; Fishbein, Evan

    2007-01-01

    Models that assess aerosol effects on regional air quality and global climate parameterize aerosol sources in terms of amount, type, and injection height. The multiangle imaging spectroradiometer (MISR) aboard NASA's Terra satellite retrieves total column aerosol optical thickness (AOT), and aerosol type over cloud-free land and water. A stereo-matching algorithm automatically retrieves reflecting-layer altitude wherever clouds or aerosol plumes have discernable spatial contrast, with about 500-m accuracy, at 1.1-km horizontal resolution. Near-source biomass burning smoke, volcanic effluent, and desert dust plumes are observed routinely, providing information about aerosol amount, particle type, and injection height useful for modeling applications. Compared to background aerosols, the plumes sampled have higher AOT, contain particles having expected differences in Angstrom exponent, size, single-scattering albedo, and for volcanic plume and dust cloud cases, particle shape. As basic thermodynamics predicts, thin aerosol plumes lifted only by regional winds or less intense heat sources are confined to the boundary layer. However, when sources have sufficient buoyancy, the representative plumes studied tend to concentrate within discrete, high-elevation layers of local stability; the aerosol is not uniformly distributed up to a peak altitude, as is sometimes assumed in modeling. MISR-derived plume heights, along with meteorological profile data from other sources, make it possible to relate radiant energy flux observed by the moderate resolution imaging spectroradiometer (MODIS), also aboard the Terra spacecraft, to convective heat flux that plays a major role in buoyant plume dynamics. A MISR climatology of plume behavior based on these results is being developed.

  20. Long-term trends in aerosol optical characteristics in the Po Valley, Italy

    NASA Astrophysics Data System (ADS)

    Putaud, J. P.; Cavalli, F.; Martins dos Santos, S.; Dell'Acqua, A.

    2014-09-01

    Aerosol properties have been monitored by ground-based in situ and remote sensing measurements at the station for atmospheric research located in Ispra, on the edge of the Po Valley, for almost one decade. In situ measurements are performed according to Global Atmosphere Watch recommendations, and quality is assured through the participation in regular inter-laboratory comparisons. Sun-photometer data are produced by the Aerosol Robotic Network (AERONET). Data show significant decreasing trends over the 2004-2010 period for a number of variables, including particulate matter (PM) mass concentration, aerosol scattering, backscattering and absorption coefficients, and aerosol optical thickness (AOT). In situ measurement data show no significant trends in the aerosol backscatter ratio, but they do show a significant decreasing trend of about -0.7 ± 0.3% yr-1 in the aerosol single scattering albedo (SSA) in the visible light range. Similar trends are observed in the SSA retrieved from sun-photometer measurements. Correlations appear between in situ PM mass concentration and aerosol scattering coefficient, on the one hand, and elemental carbon (EC) concentration and aerosol absorption coefficient, on the other hand. However, no increase in the EC / PM ratio was observed, which could have explained the decrease in SSA. The application of a simple approximation to calculate the direct radiative forcing by aerosols suggests a significant diminution in their cooling effect, mainly due to the decrease in AOT. Applying the methodology we present to those sites, where the necessary suite of measurements is available, would provide important information to inform future policies for air-quality enhancement and fast climate change mitigation.

  1. Potential source identification for aerosol concentrations over a site in Northwestern India

    NASA Astrophysics Data System (ADS)

    Payra, Swagata; Kumar, Pramod; Verma, Sunita; Prakash, Divya; Soni, Manish

    2016-03-01

    The collocated measurements of aerosols size distribution (ASD) and aerosol optical thickness (AOT) are analyzed simultaneously using Grimm aerosol spectrometer and MICROTOP II Sunphotometer over Jaipur, capital of Rajasthan in India. The contrast temperature characteristics during winter and summer seasons of year 2011 are investigated in the present study. The total aerosol number concentration (TANC, 0.3-20 μm) during winter season was observed higher than in summer time and it was dominated by fine aerosol number concentration (FANC < 2 μm). Particles smaller than 0.8 μm (at aerodynamic size) constitute ~ 99% of all particles in winter and ~ 90% of particles in summer season. However, particles greater than 2 μm contribute ~ 3% and ~ 0.2% in summer and winter seasons respectively. The aerosols optical thickness shows nearly similar AOT values during summer and winter but corresponding low Angstrom Exponent (AE) values during summer than winter, respectively. In this work, Potential Source Contribution Function (PSCF) analysis is applied to identify locations of sources that influenced concentrations of aerosols over study area in two different seasons. PSCF analysis shows that the dust particles from Thar Desert contribute significantly to the coarse aerosol number concentration (CANC). Higher values of the PSCF in north from Jaipur showed the industrial areas in northern India to be the likely sources of fine particles. The variation in size distribution of aerosols during two seasons is clearly reflected in the log normal size distribution curves. The log normal size distribution curves reveals that the particle size less than 0.8 μm is the key contributor in winter for higher ANC.

  2. Surface chemistry of surfactant AOT-stabilized SnO(2) nanoparticles and effect of temperature.

    PubMed

    Luwang, Meitram N; Ningthoujam, Raghumani S; Singh, Naorem S; Tewari, Raghvendra; Srivastava, Sri K; Vatsa, Rajesh K

    2010-09-01

    SnO(2).xH(2)O nanoparticles were prepared at room temperature by the microemulsion route. Sodium bis(2-ethylhexyl) sulfosuccinate (AOT) was used as a surfactant to stabilize the nanoparticles. These nanoparticles show green luminescence at 510nm, which has been assigned to oxygen vacancies. Infrared spectra of samples heated in the temperature range 500-900 degrees C show bond formation between SnO(2) nanoparticles and SO(4)(2-), which arises from oxidation of SO(3)(-) present in AOT. This was further supported by X-ray diffraction. Shape transformations of the particles from triangular to spherical and then to rectangular was observed as the heat-treatment temperature was increased, and this is related to the surface energy of particles. An enhancement in emission intensity of Eu(3+) was observed when Eu(3+) ions were doped into the SnO(2) nanoparticles due to significant energy transfer from SnO(2) (or Eu-O) to Eu(3+) through surface-mediated energy transfer as compared to direct excitation of Eu(3+) at 397nm. Interestingly, these nanoparticles are dispersible in water, and can be incorporated into polymer-based materials such as polyvinyl alcohol to give homogeneous films, giving rise to blue and red emissions. PMID:20557894

  3. Cy3 in AOT reverse micelles II. Probing intermicellar interactions using fluorescence correlation spectroscopy.

    PubMed

    McPhee, Jeffrey T; Scott, Eric; Levinger, Nancy E; Van Orden, Alan

    2011-08-11

    Cyanine-3 (Cy3) fluorescent dye molecules confined in sodium di-2-ethylhexyl sulfosuccinate (AOT) reverse micelles were examined using dynamic light scattering and fluorescence correlation spectroscopy to probe the kinetics of Cy3 dye and reverse micelle aggregation. This study explored a range of reverse micelle sizes, defined as w(0) = [H(2)O]/[AOT], in which the occupation number ranged from one Cy3 molecule per ∼10(5) to ∼10(6) reverse micelles. These measurements reveal that in the smallest reverse micelle, w(0) = 1, the Cy3 molecules aggregate to form H-aggregate dimers, and the Cy3 dimerization is accompanied by the formation of a transient dimer between reverse micelles. Transient reverse micelle dimer particles are only observed in the small fraction of Cy3-labeled reverse micelles probed by fluorescence correlation spectroscopy and are not observed in the bulk solution probed by dynamic light scattering. Furthermore, fluorescence correlation spectroscopy makes it possible to probe the size and shape of these dimers, revealing prolate ellipsoid-shaped particles with twice the volume and surface area of a single reverse micelle. PMID:21761943

  4. Studies on the catalytic behaviour of a cholinesterase-like abzyme in an AOT microemulsion system.

    PubMed

    Franqueville, Eric; Stamatis, Haralambos; Loutrari, Heleni; Friboulet, Alain; Kolisis, Fragiskos

    2002-08-01

    The hydrolytic activity of a monoclonal catalytic antibody (9A8) (abzyme) with acetylcholinesterase-like activity was investigated in water-in-oil (w/o) microemulsions (reverse micelles) based on sodium bis-2-(ethylhexyl)sulfosuccinate (AOT) in isooctane, using p- and o-nitrophenylacetate (p-and o-NPA) as substrates. The dependence of the abzyme hydrolytic activity on the molar ratio of water to surfactant (w(o)) showed a bell-shaped curve, presenting a maximum at w(o)=11.1. An increase of the AOT concentration at constant w(o), resulted in a decrease of the catalytic activity suggesting a possible inhibition effect of the surfactant. The incorporation of the abzyme into the reverse micelle system caused a blue shift of the fluorescence emission maximum by a magnitude of 7-10 nm depending on the w(o) value. This result indicates that the antibody molecule, or a large part of it, is located in the aqueous microphase of the system. Kinetic studies showed that the hydrolysis of p-and o-NPA in microemulsion system as well as in aqueous solution follows Michaelis-Menten kinetics. The catalytic efficiency (k(cat)/K(m)) in w/o microemulsion was significant lower than in aqueous solution. PMID:12067523

  5. Three-dimensional dust aerosol distribution and extinction climatology over northern Africa simulated with the ALADIN numerical prediction model from 2006 to 2010

    NASA Astrophysics Data System (ADS)

    Mokhtari, M.; Tulet, P.; Fischer, C.; Bouteloup, Y.; Bouyssel, F.; Brachemi, O.

    2015-08-01

    The seasonal cycle and optical properties of mineral dust aerosols in northern Africa were simulated for the period from 2006 to 2010 using the numerical atmospheric model ALADIN (Aire Limitée Adaptation dynamique Développement InterNational) coupled to the surface scheme SURFEX (SURFace EXternalisée). The particularity of the simulations is that the major physical processes responsible for dust emission and transport, as well as radiative effects, are taken into account on short timescales and at mesoscale resolution. The aim of these simulations is to quantify the dust emission and deposition, locate the major areas of dust emission and establish a climatology of aerosol optical properties in northern Africa. The mean monthly aerosol optical thickness (AOT) simulated by ALADIN is compared with the AOTs derived from the standard Dark Target (DT) and Deep Blue (DB) algorithms of the Aqua-MODIS (MODerate resolution Imaging Spectroradiometer) products over northern Africa and with a set of sun photometer measurements located at Banizoumbou, Cinzana, Soroa, Mbour and Cape Verde. The vertical distribution of dust aerosol represented by extinction profiles is also analysed using CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations. The annual dust emission simulated by ALADIN over northern Africa is 878 Tg year-1. The Bodélé Depression appears to be the main area of dust emission in northern Africa, with an average estimate of about 21.6 Tg year-1. The simulated AOTs are in good agreement with satellite and sun photometer observations. The positions of the maxima of the modelled AOTs over northern Africa match the observed positions, and the ALADIN simulations satisfactorily reproduce the various dust events over the 2006-2010 period. The AOT climatology proposed in this paper provides a solid database of optical properties and consolidates the existing climatology over this region derived from satellites, the AERONET network and regional climate

  6. Comparison of Aerosol Classification from Airborne High Spectral Resolution Lidar and the CALIPSO Vertical Feature Mask

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Omar, A. H.; Hostetler, C. A.; Hair, J. W.; Rogers, R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.

    2012-12-01

    applications. The HSRL products are used to apportion AOT by type and vertical location in the column, and to characterize the frequency of cases where multiple types are present in the column. Resolving scenes with multiple types in the column is not possible with passive imaging radiometer and polarimeter measurements. The HSRL aerosol type also has higher resolution than the CALIPSO layer-wise product and provides insight into the performance of CALIPSO layer separation. Information about the vertical distribution of aerosol types is useful for estimating radiative forcing, understanding aerosol lifetime and transport, and assessing the predictions of transport models. CALIPSO has been a pathfinder, providing the first long-term global data set of aerosol vertical distribution. Based on our results, a future satellite lidar similar to CALIPSO, but with the addition of polarization sensitivity at 1064 nm and the HSRL technique at 532 nm, could provide a significant advance in characterizing the vertical distribution of aerosol.

  7. Validation of MODIS aerosol product with in-situ AERONET data (a study case in Hermosillo, Sonora, Mexico)

    NASA Astrophysics Data System (ADS)

    Valdes, M.; Leyva-Contreras, A.; Bonifaz, R.; Llamas, R.

    2009-12-01

    The aerosol optical thickness (AOT) is known as blocking particles which avoid the transmission of solar radiation coming from the Sun, and is defined as the integral of the coefficient of extinction over a vertical column of the Atmosphere. This coefficient of extinction is also defined as the limited fraction of the irradiance over the trajectory at a specific wavelength. The MODIS (Moderate Resolution Imaging Spectroradiometer) sensor provides aerosol data products all over the planet. However this data requires constant evaluation and validation using in-situ data such as the provided by the network of photometers managed by AERONET (Aerosol Robotic Network). In this work, the procedure of validation of the MODIS AOT data using AERONET data in the wavelengths of 660 and 675 nm is presented. It is expected that using validate remote sensing data which provides spatial and temporal information about the AOT will help to a better understanding of the behavior of the complex atmospheric conditions which characterize the NW of Mexico and SW of the US such as the Mexican monsoon.

  8. Long-term changes in the aerosol optical thickness in moscow and correction under strong atmospheric turbidity

    NASA Astrophysics Data System (ADS)

    Gorbarenko, E. V.; Rublev, A. N.

    2016-03-01

    We have estimated and compensated the error in long-term series of the aerosol optical thickness (AOT) calculated from the data on direct integral solar radiation measured by a standard actinometer at the Meteorological Observatory of the Moscow State University (MO MSU) for strong atmospheric turbidity conditions. The necessary corrections have been obtained by the Monte-Carlo simulation of the actinometry measurements for different atmospheric conditions, taking into account the angular size of the field of view of the instrument; and a special correctional formula has been obtained. This correction formula has been applied for all timed AOT values of above 0.5 observed at the MO MSU for the entire time period from 1955 to 2013. Changes in the long-term average AOT values in Moscow occurred only when the smoky haze from the forest and peat fires affected the aerosol turbidity of the atmosphere. Here, the significant decreasing trend of aerosol optical depth of the atmosphere from 1955 to 2013 has been retained with the same confidence level.

  9. Comparison of Aerosol Classification Results from Airborne High Spectral Resolution Lidar (HSRL) Measurements and the Calipso Vertical Feature Mask

    NASA Technical Reports Server (NTRS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Obland, M. D.; Butler, C. F.; Cook, A. L.; Harper, D. B.; Froyd, K. D.; Omar, A.

    2012-01-01

    Knowledge of the vertical profile, composition, concentration, and size of aerosols is required for assessing the direct impact of aerosols on radiation, the indirect effects of aerosols on clouds and precipitation, and attributing these effects to natural and anthropogenic aerosols. Because anthropogenic aerosols are predominantly submicrometer, fine mode fraction (FMF) retrievals from satellite have been used as a tool for deriving anthropogenic aerosols. Although column and profile satellite retrievals of FMF have been performed over the ocean, such retrievals have not yet been been done over land. Consequently, uncertainty in satellite estimates of the anthropogenic component of the aerosol direct radiative forcing is greatest over land, due in large part to uncertainties in the FMF. Satellite measurements have been used to detect and evaluate aerosol impacts on clouds; however, such efforts have been hampered by the difficulty in retrieving vertically-resolved cloud condensation nuclei (CCN) concentration, which is the most direct parameter linking aerosol and clouds. Recent studies have shown correlations between average satellite derived column aerosol optical thickness (AOT) and in situ measured CCN. However, these same studies, as well as others that use detailed airborne in situ measurements have noted that vertical variability of the aerosol distribution, impacts of relative humidity, and the presence of coarse mode aerosols such as dust introduce large uncertainties in such relations.

  10. Comparison of Aerosol Optical Properties and Water Vapor Among Ground and Airborne Lidars and Sun Photometers During TARFOX

    NASA Technical Reports Server (NTRS)

    Ferrare, R.; Ismail, S.; Browell, E.; Brackett, V.; Clayton, M.; Kooi, S.; Melfi, S. H.; Whiteman, D.; Schwemmer, G.; Evans, K.; Russell, P.; Livingston, J.; Schmid, B.; Holben, B.; Remer, L.; Smirnov, A.; Hobbs, P. V.

    2000-01-01

    We compare aerosol optical thickness (AOT) and precipitable water vapor (PWV) measurements derived from ground and airborne lidars and Sun photometers during TARFOX (Tropospheric Aerosol Radiative Forcing Observational Experiment). Such comparisons are important to verify the consistency between various remote sensing measurements before employing them in any assessment of the impact of aerosols on the global radiation balance. Total scattering ratio and extinction profiles measured by the ground-based NASA/GSFC Scanning Raman Lidar (SRL) system, which operated from Wallops Island, Virginia (37.86 deg N, 75.51 deg W), are compared with those measured by the Lidar Atmospheric Sensing Experiment (LASE) airborne lidar system aboard the NASA ER-2 aircraft. Bias and rms differences indicate that these measurements generally agreed within about 10%. Aerosol extinction profiles and estimates of AOT are derived from both lidar measurements using a value for the aerosol extinction/backscattering ratio S(sub a)=60 sr for the aerosol extinction/backscattering ratio, which was determined from the Raman lidar measurements.

  11. Aerosol retrieval from twilight photographs taken by a digital camera

    NASA Astrophysics Data System (ADS)

    Saito, M.; Iwabuchi, H.

    2014-12-01

    Twilight sky, one of the most beautiful sights seen in our daily life, varies day by day, because atmospheric components such as ozone and aerosols also varies day by day. Recent studies have revealed the effects of tropospheric aerosols on twilight sky. In this study, we develop a new algorithm for aerosol retrievals from twilight photographs taken by a digital single reflex-lens camera in solar zenith angle of 90-96˚ with interval of 1˚. A radiative transfer model taking spherical-shell atmosphere, multiple scattering and refraction into account is used as a forward model, and the optimal estimation is used as an inversion calculation to infer the aerosol optical and radiative properties. The sensitivity tests show that tropospheric (stratospheric) aerosol optical thickness is responsible to the distribution of twilight sky color and brightness near the horizon (in viewing angles of 10˚ to 20˚) and aerosol size distribution is responsible to the angular distribution of brightness near the solar direction. The AOTs are inferred with small uncertainties and agree very well with that from the Skyradiometer. In this conference, several case studies using the algorithm will be shown.

  12. 75 FR 61572 - Open Meeting of the OTS Mutual Savings Association Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE TREASURY Office of Thrift Supervision Open Meeting of the OTS Mutual Savings Association Advisory Committee AGENCY: Department of the Treasury, Office of Thrift Supervision. ACTION: Notice of meeting. SUMMARY: The OTS...

  13. 12 CFR 502.25 - How does OTS determine my complexity component?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false How does OTS determine my complexity component... determine my complexity component? If you are a savings association and your portfolio exceeds any of the thresholds in paragraph (a) of this section, OTS will calculate your complexity component according...

  14. 12 CFR 502.60 - When will OTS adjust, add, waive, or eliminate a fee?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 6 2012-01-01 2012-01-01 false When will OTS adjust, add, waive, or eliminate... TREASURY ASSESSMENTS AND FEES Fees § 502.60 When will OTS adjust, add, waive, or eliminate a fee? Under unusual circumstances, the Director may deem it necessary or appropriate to adjust, add, waive,...

  15. 12 CFR 502.60 - When will OTS adjust, add, waive, or eliminate a fee?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 6 2014-01-01 2012-01-01 true When will OTS adjust, add, waive, or eliminate a... ASSESSMENTS AND FEES Fees § 502.60 When will OTS adjust, add, waive, or eliminate a fee? Under unusual circumstances, the Director may deem it necessary or appropriate to adjust, add, waive, or eliminate a fee....

  16. 12 CFR 502.60 - When will OTS adjust, add, waive, or eliminate a fee?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 6 2013-01-01 2012-01-01 true When will OTS adjust, add, waive, or eliminate a... ASSESSMENTS AND FEES Fees § 502.60 When will OTS adjust, add, waive, or eliminate a fee? Under unusual circumstances, the Director may deem it necessary or appropriate to adjust, add, waive, or eliminate a fee....

  17. 12 CFR 502.60 - When will OTS adjust, add, waive, or eliminate a fee?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false When will OTS adjust, add, waive, or eliminate... TREASURY ASSESSMENTS AND FEES Fees § 502.60 When will OTS adjust, add, waive, or eliminate a fee? Under unusual circumstances, the Director may deem it necessary or appropriate to adjust, add, waive,...

  18. 12 CFR 502.60 - When will OTS adjust, add, waive, or eliminate a fee?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false When will OTS adjust, add, waive, or eliminate... TREASURY ASSESSMENTS AND FEES Fees § 502.60 When will OTS adjust, add, waive, or eliminate a fee? Under unusual circumstances, the Director may deem it necessary or appropriate to adjust, add, waive,...

  19. 12 CFR 563b.295 - Will OTS require me to re-solicit proxies?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Will OTS require me to re-solicit proxies? 563b.295 Section 563b.295 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY... to re-solicit proxies? If you amend your application for conversion, OTS may require you to...

  20. 12 CFR 563b.295 - Will OTS require me to re-solicit proxies?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false Will OTS require me to re-solicit proxies? 563b.295 Section 563b.295 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY... to re-solicit proxies? If you amend your application for conversion, OTS may require you to...

  1. MASTER-IAC: QSO 2QZ J132407-0032 optical flare and OT

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Shurpakov, S.; Lipunov, V.; Gorbovskoy, E.; Rebolo, R.; Ricart, M. Serra; Israelian, G.; Lodieu, N.; Tiurina, N.; Kornilov, V.; Gress, O.; Kuznetsov, A.; Gorbunov, I.; Vlasenko, D.; Shumkov, V.; Vladimirov, V.

    2016-02-01

    MASTER-IAC auto-detection system( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 03h 32m 39.21s +19d 32m 15.0s on 2016-02-12.86192 UT. The OT unfiltered magnitude is 17.1 (limit 19.2m).

  2. 12 CFR 555.300 - Must I inform OTS before I use electronic means or facilities?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Must I inform OTS before I use electronic means... THE TREASURY ELECTRONIC OPERATIONS Requirements Applicable to All Savings Associations § 555.300 Must I inform OTS before I use electronic means or facilities? (a) General. A savings association...

  3. 12 CFR 516.10 - How does OTS compute time periods under this part?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false How does OTS compute time periods under this part? 516.10 Section 516.10 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY APPLICATION PROCESSING PROCEDURES § 516.10 How does OTS compute time periods under this part? In...

  4. 12 CFR 516.10 - How does OTS compute time periods under this part?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false How does OTS compute time periods under this part? 516.10 Section 516.10 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY APPLICATION PROCESSING PROCEDURES § 516.10 How does OTS compute time periods under this part? In...

  5. 12 CFR 516.10 - How does OTS compute time periods under this part?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 6 2013-01-01 2012-01-01 true How does OTS compute time periods under this part? 516.10 Section 516.10 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY APPLICATION PROCESSING PROCEDURES § 516.10 How does OTS compute time periods under this part? In...

  6. 12 CFR 516.10 - How does OTS compute time periods under this part?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 6 2014-01-01 2012-01-01 true How does OTS compute time periods under this part? 516.10 Section 516.10 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY APPLICATION PROCESSING PROCEDURES § 516.10 How does OTS compute time periods under this part? In...

  7. 12 CFR 516.10 - How does OTS compute time periods under this part?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 6 2012-01-01 2012-01-01 false How does OTS compute time periods under this part? 516.10 Section 516.10 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY APPLICATION PROCESSING PROCEDURES § 516.10 How does OTS compute time periods under this part? In...

  8. 12 CFR 516.250 - Will OTS require me to publish a new public notice?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Will OTS require me to publish a new public... publish a new public notice? (a) If your application was subject to a publication requirement, OTS may require you to publish a new public notice of your application if: (1) You submitted a revision to...

  9. Absorbing Aerosols Above Cloud: Detection, Quantitative Retrieval, and Radiative Forcing from Satellite-based Passive Sensors

    NASA Astrophysics Data System (ADS)

    Jethva, H.; Torres, O.; Remer, L. A.; Bhartia, P. K.

    2012-12-01

    Light absorbing particles such as carbonaceous aerosols generated from biomass burning activities and windblown dust particles can exert a net warming effect on climate; the strength of which depends on the absorption capacity of the particles and brightness of the underlying reflecting background. When advected over low-level bright clouds, these aerosols absorb the cloud reflected radiation from ultra-violet (UV) to shortwave-IR (SWIR) and makes cloud scene darker-a phenomenon commonly known as "cloud darkening". The apparent "darkening" effect can be seen by eyes in satellite images as well as quantitatively in the spectral reflectance measurements made by space borne sensors over regions where light absorbing carbonaceous and dust aerosols overlay low-level cloud decks. Theoretical radiative transfer simulations support the observational evidence, and further reveal that the strength of the cloud darkening and its spectral signature (or color ratio) between measurements at two wavelengths are a bi-function of aerosol and cloud optical thickness (AOT and COT); both are measures of the total amount of light extinction caused by aerosols and cloud, respectively. Here, we developed a retrieval technique, named as the "color ratio method" that uses the satellite measurements at two channels, one at shorter wavelength in the visible and one at longer wavelength in the shortwave-IR for the simultaneous retrieval of AOT and COT. The present technique requires assumptions on the aerosol single-scattering albedo and aerosol-cloud separation which are supplemented by the Aerosol Robotic Network (AERONET) and space borne CALIOP lidar measurements. The retrieval technique has been tested making use of the near-UV and visible reflectance observations made by the Ozone Monitoring Instrument (OMI) and Moderate Resolution Imaging Spectroradiometer (MODIS) for distinct above-cloud smoke and dust aerosol events observed seasonally over the southeast and tropical Atlantic Ocean

  10. Characterizing the Vertical Distribution of Aerosols Over the ARM SGP Site

    SciTech Connect

    Richard Ferrare, Connor Flynn, David Turner

    2009-05-05

    . Analysis of the aerosol and water vapor data collected by the Raman lidar during the 2003 Aerosol IOP indicated that the sensitivity of the lidar was significantly lower than when the lidar was initially deployed. A detailed analysis after the IOP of the long-term dataset demonstrated that the lidar began degrading in early 2002, and that it lost approximately a factor of 4 in sensitivity between 2002 and 2004. We participated in the development of the remediation plan for the system to restore its initial performance. We conducted this refurbishment and upgrade from May- September 2004. This remediation lead to an increase in the signal-to-noise ratio of 10 and 30 for the Raman lidar's water vapor mixing ratio and aerosol backscatter coefficient data, respectively as compared to the signal strengths when the system was first deployed. The DOE ARM Aerosol Lidar Validation Experiment (ALIVE), which was conducted during September 2005, evaluated the impact of these modifications and upgrades on the SGP Raman lidar measurements of aerosol extinction and optical thickness. The CARL modifications significantly improved the accuracy and temporal resolution of the aerosol measurements. Aerosol extinction profiles measured by the Raman lidar were also used to evaluate aerosol extinction profiles and aerosol optical thickness (AOT) simulated by aerosol models as part of the Aerosol module inter-Comparison in global models (AEROCOM) (http://nansen.ipsl.jussieu.fr/AEROCOM/aerocomhome.html) project. There was a wide range in how the models represent the aerosol extinction profiles over the ARM SGP site, even though the average annual AOT represented by the various models and measured by CARL and the Sun photometer were in general agreement, at least within the standard deviations of the averages. There were considerable differences in the average vertical distributions among the models, even among models that had similar average aerosol optical thickness. Deviations between mean

  11. Variation of aerosol characteristics in the detail scale of time and space

    NASA Astrophysics Data System (ADS)

    Mukai, S.; Nakata, M.; Sano, I.

    2012-04-01

    In this work, we intend to demonstrate the spatial and temporal variation of atmospheric aerosols around AERONET/Osaka site. Osaka is the second big city in Japan and a typical Asian urban area. It is well known that the aerosol distribution in Asia is complicated due to the increasing emissions of anthropogenic aerosols in association with economic growth and in addition behavior of natural dusts significantly varies with the seasons. Therefore local spatially and temporally resolved measurements of atmospheric particles in Asian urban city are meaningful. We equip various ground measurement devices of atmosphere in the campus of Kinki University (KU). The data supplied by the Cimel instrument are analyzed with a standard AERONET (Aerosol Robotics Network) processing system. It provides us with Aerosol optical thickness (AOT), the Ångström exponent and so on. We set up a PM sampler and a standard instrument of NIES/LIDAR network attached to our AERONET site. The PM sampler provides particle information about the concentrations of PM2.5, PM10 and OBC separately. In addition to the simultaneous measurements, we make observation of the air quality at several locations in the neighbour-hood using portable sun-photometers (Solar-Light Company Microtops-2). The simultaneous measurements of aerosols and numerical model simulations indicate that the spatial and temporal factors influence the characterization of atmospheric particles especially in dust event. Then we observe the air quality at such several locations within a few 10 km area from KU, as Izumi and Nara, in ordinal days and dust days. Izumi site locates near industrial area and Nara is in the east of KU beyond the mountain-Ikoma. It is found from the simultaneous measurements at these three sites that AOT at Izumi in ordinal days is the highest and Nara's lowest. It indicates that the Ikoma-mountains block off the polluted air from the west. However in dust days, AOT at Nara is as large as that at Higashi

  12. Structural and dynamical characterization of unilamellar AOT vesicles in aqueous solutions and their efficacy as potential drug delivery vehicle.

    PubMed

    Saha, Ranajay; Verma, Pramod Kumar; Mitra, Rajib Kumar; Pal, Samir Kumar

    2011-11-01

    Sodium bis(2-ethylhexyl) sulfosuccinate (AOT) is well known to form nanometre sized aqueous droplets in organic solvents and used in several contemporary applications including templates of nanoparticle synthesis. However, the detailed structural characterization of AOT in aqueous media is relatively less attended. Here we have used dynamic light scattering technique for the structural characterization of AOT in aqueous solutions and found to have a monodispersed, unilamellar vesicles (∼140 nm diameter). The efficacy of the vesicle to host both charged drugs like H258 (2'-(4-hydroxyphenyl)-5-[5-(4-methylpiperazine-1-yl)-benzimidazo-2-yl-benzimidazole]), EtBr (ethidium bromide) and hydrophobic drug like DCM (4-(dicyanomethylene)-2-methyl-6-(p-dimethylamino-styryl)-4H-pyran) has also been investigated using Förster resonance energy transfer. Picosecond resolved and polarization gated spectroscopy have been used to study the solvation dynamics and microviscosity at the surface of the vesicles. We have also performed concentration and temperature dependent studies in order to confirm the stability of the vesicles in aqueous phase. The drug release profile of the vesicles has been studied through in vitro dialysis method. The non-toxic, monodispersed vesicles in aqueous media with a noteworthy stability in wide range of AOT concentration and temperature, capable of hosting drugs of various natures (both hydrophobic and charged) simultaneously for many codelivery applications with controlled drug release profile may find its applications in drug delivery. PMID:21816579

  13. Spectroscopic study of the melting and reconstruction of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles from their frozen states.

    PubMed

    Suzuki, Akira; Yui, Hiroharu

    2015-04-01

    The confinement of water in organic self-assemblies with nanometer-sized pores is ubiquitous in nature. Water pools in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles have been intensively studied as a representative model of such confined water. However, the freezing and melting behavior of such water pools is poorly understood owing to their poor structural stability under phase transition. In the present work, the melting of iced water pools accompanied by a reconstruction of AOT reverse micelles was studied with infrared spectroscopy. For all AOT reverse micelles tested (Rw: 1.2-4.4 nm), a characteristic ice-water coexistence phase was observed during melting. The results provide experimental evidence of the previously proposed core-shell structure of the water pool. For larger frozen reverse micelles (Rw>2.3 nm), shifts of the υ(OH) bands were observed. The spectra of the shifted υ(OH) bands were similar to those for the melted water pools in the smaller micelles. The mechanism of the reconstruction of AOT reverse micelles from their frozen states and the corresponding transient changes in the local environments were also discussed. PMID:25569193

  14. Structural effects of the β-vinyl linker in pyridinium porphyrins: spectroscopic studies in organic solvents and AOT reverse micelles.

    PubMed

    Vaz Serra, Vanda; Andrade, Suzana M; Silva, Eduarda M P; Silva, Artur M S; Neves, Maria G P M S; Costa, Sílvia M B

    2013-12-01

    Two isomeric β-vinylpyridinium porphyrins, 2-[2-(2-methylpyridinium)vinyl]-5,10,15,20-tetraphenylporphyrin (1, ortho isomer) and 2-[2-(4-methylpyridinium)vinyl]-5,10,15,20-tetraphenylporphyrin (2, para isomer), which have shown different photodynamic behavior were investigated in organic solvents and sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles. In organic systems, the absorption spectra present a red-shifted band that is more intense in the para isomer, in addition to the usual Soret band. This new band presents interesting solvatochromic effects which obey the multiparametric Kamlet-Taft equation. In AOT reverse micelles, the ortho isomer exhibits a strong dependence with the parameter ω0 = [H2O]/[AOT] which indicates that the molecule resides at the interface toward the organic phase. By contrast, no evidence was detected for the encapsulation of para isomer 2 in AOT reverse micelles. The hypothesis of two ground state isomers with different contributions of trans and quinoid structures is advanced on the basis of the overall data collected from electronic absorption, steady-state, and transient-state fluorescence emission. A charge transfer state in which an electron is fully transferred from the porphyrin to the pyridinium moiety is associated to a quinoid structure in isomer 2. The trans/quinoid relative proportions may be accounted for by the orientation of the ortho-/para-pyridinium isomers relatively to the porphyrin core. PMID:24175940

  15. Effect of the constrained environment on the interactions between the surfactant and different polar solvents encapsulated within AOT reverse micelles.

    PubMed

    Durantini, Andrés M; Falcone, R Dario; Silber, Juana J; Correa, N Mariano

    2009-08-24

    Herein, we report a study of the interactions between different nonaqueous polar solvents, namely, ethylene glycol (EG), propylene glycol (PG), glycerol (GY), dimethylformamide (DMF), and dimethylacetamide (DMA), and the polar heads of sodium 1,4-bis-2-ethylhexylsulfosuccinate (AOT) in nonaqueous AOT/n-heptane reverse micelles. The goal of our study is to gain insights into the unique reverse-micelle microenvironment created upon encapsulation of these polar solvents. For the first time, the study is focused on determining which regions of the AOT molecular structure are involved in the interactions with the polar solvents. We use FTIR spectroscopy--a noninvasive technique--to follow the changes in the AOT C=O band and the symmetric and asymmetric SO(3)(-) vibration modes upon increasing the content of polar solvents in the micelles. The results show that GY interacts through H bonds with the SO(3)(-) group, thereby removing the Na(+) counterions from the interface remaining in the polar core of the micelles. PG and EG interact through H bonds, mainly with the C=O group of AOT, penetrating into the oil side of the interface. Thus, they interact weakly with the Na(+) counterion, which seems to be close to the AOT sulfonate group. Finally, DMF and DMA, encapsulated inside the reverse micelles, interact neither with the C=O nor with the SO(3)(-) groups, but their weakly bulk-associated structure is broken because of the interactions with Na(+). We suggest that DMF and DMA can complex the Na(+) ions through their carbonyl and nitrogen groups. Hence, our results do not only give insights into how the constrained environment affects the bulk properties of polar solvents encapsulated within reverse micelles but--more importantly--they also help us to answer the tricky question about which regions of the AOT moiety are involved in the interactions with the polar solvents. We believe that our results show a clear picture of the interactions present at the nonaqueous reverse

  16. An important fingerprint of wildfires on the European aerosol load

    NASA Astrophysics Data System (ADS)

    Barnaba, F.; Angelini, F.; Curci, G.; Gobbi, G. P.

    2011-10-01

    Wildland fires represent the major source of fine aerosols, i.e., atmospheric particles with diameters <1 μm. The largest numbers of these fires occur in Africa, Asia and South America, but a not negligible fraction also occurs in Eastern Europe and former USSR countries, particularly in the Russian Federation, Ukraine and Kazakhstan. Besides the impact of large forest fires, recent studies also highlighted the crucial role played by routine agricultural fires in Eastern Europe and Russia on the Arctic atmosphere. An evaluation of the impact of these fires over Europe is currently not available. The assessment of the relative contribution of fires to the European aerosol burden is hampered by the complex mixing of natural and anthropogenic particle types across the continent. In this study we use long term (2002-2007) satellite-based fires and aerosol data coupled to atmospheric trajectory modelling in the attempt to estimate the wildfires contribution to the European aerosol optical thickness (AOT). Based on this dataset, we provide evidence that fires-related aerosols play a major role in shaping the AOT yearly cycle at the continental scale. In general, the regions most impacted by wildfires emissions and/or transport are Eastern and Central Europe as well as Scandinavia. Conversely, a minor impact is found in Western Europe and in the Western Mediterranean. We estimate that in spring 5 to 35% of the European fine fraction AOT (FFAOT) is attributable to wildland fires. The estimated impact maximizes in April (20-35%) in Eastern and Central Europe as well as in Scandinavia and in the Central Mediterranean. An important contribution of wildfires to the FFAOT is also found in summer over most of the continent, particularly in August over Eastern Europe (28%) and the Mediterranean regions, from Turkey (34%) to the Western Mediterranean (25%). Although preliminary, our results suggest that this fires-related, continent-wide haze plays a not negligible role on the

  17. An Energetic Perspective on Aerosol Radiative Forcing and Interactions with Atmospheric Wave Activity

    NASA Astrophysics Data System (ADS)

    Hosseinpour, F.; Wilcox, E. M.; Colarco, P. R.

    2014-12-01

    Aerosols have the capability to alter regional-scale atmospheric circulations. A better understanding of the contribution of aerosols to multi-scale atmospheric phenomena and their transient changes is crucial for efforts to evaluate climate predictions using next generation climate models. In this study we address the following questions: (1) Is there a mechanistic relationship between variability of oceanic dust aerosol forcing and transient changes in the African easterly jet- African easterly wave (AEJ-AEW) system? (2) What are the long-term impacts of possible aerosol-wave interactions on climate dynamics of eastern tropical Atlantic Ocean and western African monsoon (WAM) region during boreal summer seasons? Our hypothesis is that aerosol radiative forcing may act as additional energy source to fuel the development of African easterly waves on the northern and southern sides of the AEJ. Evidence in support of this hypothesis is presented based on analysis of an ensemble of NASA satellite data sets, including aerosol optical thickness (AOT) observations from the Moderate Resolution Imaging Spectro-radiometer (MODIS) and the Sea-Viewing Wide Field-of-View Sensor (SeaWiFS), as well as an atmospheric reanalysis from the Modern-Era Retrospective Analysis for Research and Applications (MERRA) and a simulation of global aerosol distributions made with the Goddard Earth Observing System Model version 5 (GEOS-5) Earth system model with meteorology constrained by MERRA and an assimilation of MODIS AOT (MERRAero). We propose that the impacts of Saharan aerosols on the regional climate dynamics occur through contributions to the eddy energy of waves with 2—7-day and 7—11-day variability.

  18. Radiation Susceptibility Assessment of Off the Shelf (OTS) Hardware

    NASA Technical Reports Server (NTRS)

    Culpepper, William X.; Nicholson, Leonard L. (Technical Monitor)

    2000-01-01

    The reduction in budgets, shortening of schedules and necessity of flying near state of the art technology have forced projects and designers to utilize not only modern, non-space rated EEE parts but also OTS boards, subassemblies and systems. New instrumentation, communications, portable computers and navigation systems for the International Space Station, Space Shuttle, and Crew Return Vehicle are examples of the realization of this paradigm change at the Johnson Space Center. Because of this change, there has been a shift in the radiation assessment methodology from individual part testing using low energy heavy ions to board and box level testing using high-energy particle beams. Highlights of several years of board and system level testing are presented along with lessons learned, present areas of concern, insights into test costs, and future challenges.

  19. 12 CFR 550.70 - Must I obtain OTS approval or file a notice before I exercise fiduciary powers?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... before I exercise fiduciary powers? 550.70 Section 550.70 Banks and Banking OFFICE OF THRIFT SUPERVISION... I obtain OTS approval or file a notice before I exercise fiduciary powers? You should refer to the following chart to determine if you must obtain OTS approval or file a notice with OTS before you...

  20. 12 CFR 550.70 - Must I obtain OTS approval or file a notice before I exercise fiduciary powers?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... before I exercise fiduciary powers? 550.70 Section 550.70 Banks and Banking OFFICE OF THRIFT SUPERVISION... I obtain OTS approval or file a notice before I exercise fiduciary powers? You should refer to the following chart to determine if you must obtain OTS approval or file a notice with OTS before you...

  1. 12 CFR 550.70 - Must I obtain OTS approval or file a notice before I exercise fiduciary powers?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... before I exercise fiduciary powers? 550.70 Section 550.70 Banks and Banking OFFICE OF THRIFT SUPERVISION... I obtain OTS approval or file a notice before I exercise fiduciary powers? You should refer to the following chart to determine if you must obtain OTS approval or file a notice with OTS before you...

  2. 12 CFR 550.70 - Must I obtain OTS approval or file a notice before I exercise fiduciary powers?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... before I exercise fiduciary powers? 550.70 Section 550.70 Banks and Banking OFFICE OF THRIFT SUPERVISION... I obtain OTS approval or file a notice before I exercise fiduciary powers? You should refer to the following chart to determine if you must obtain OTS approval or file a notice with OTS before you...

  3. 12 CFR 550.70 - Must I obtain OTS approval or file a notice before I exercise fiduciary powers?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... before I exercise fiduciary powers? 550.70 Section 550.70 Banks and Banking OFFICE OF THRIFT SUPERVISION... I obtain OTS approval or file a notice before I exercise fiduciary powers? You should refer to the following chart to determine if you must obtain OTS approval or file a notice with OTS before you...

  4. Towards climatological study on the characteristics of aerosols in Central Africa and Mediterranean sites

    NASA Astrophysics Data System (ADS)

    Benkhalifa, Jamel; Chaabane, Mabrouk

    2016-02-01

    The atmosphere contains molecules, clouds and aerosols that are sub-millimeter particles having a large variability in size, shape, chemical composition, lifetime and contents. The aerosols concentration depends greatly on the geographical situation, meteorological and environmental conditions, which makes aerosol climatology difficult to assess. Setting up a solar photometer (automatic, autonomous and portable instrument) on a given site allows carrying out the necessary measurements for aerosol characterization. The particle microphysical and optical properties are obtained from photometric measurements. The objective of this study is to analyze the spatial variability of aerosol optical thickness (AOT) in several Mediterranean regions and Central Africa, we considered a set of simultaneous data in the AErosol RObotic NETwork (AERONET) from six sites, two of which are located in Central Africa (Banizoumbou and Zinder Airport) and the rest are Mediterranean sites (Barcelona, Malaga, Lampedusa, and Forth Crete). The results have shown that the physical properties of aerosols are closely linked to the climate nature of the studied site. The optical thickness, single scattering albedo and aerosols size distribution can be due to the aging of the dust aerosol as they are transported over the Mediterranean basin.

  5. Oil Induced Spontaneous Flow in Water- Bis(2-ethylhexyl)Sulfosuccinat (AOT) system

    NASA Astrophysics Data System (ADS)

    Kalakonda, Parvathalu

    Instability and evaporation rates of oils within the layers of vesicles of a surfactants trigger the spontaneous (second flow) flow. The incorporation of oils into bis(2-ethylhexyl)sulfosuccinat (AOT) system remains incompletely characterized. We show that the second flow has a finite size that show a minimum at a particular concentration (mM) of surfactant solution. As a result, the layers are destabilized lead to ``explode'' and create the second flow. The fluorescence emission spectra and evaporation rates show that the oil diffuses into the layers of vesicles of a surfactant. We have characterized evaporation rates of oils on various concentrations (mM) of surfactant solution and observed that oils evaporation rates depend on volume and remain constant as the function of concentration of surfactant. We believe that second flow is new feature and brings a new insight into the fluid flow dynamics.

  6. Synthesis and characterization of ZnS nanowires by AOT micelle-template inducing reaction

    SciTech Connect

    Lv Ruitao; Cao Chuanbao; Zhu Hesun

    2004-08-03

    ZnS nanowires, with diameters around 30 nm and lengths up to 2.5 {mu}m, had been successfully synthesized from solutions containing an anionic surfactant, sodium bis(2-ethylhexyl)sulfosuccinate (AOT). Powder X-ray diffraction (XRD) pattern, energy-dispersive X-ray spectroscopy (EDS) and selected-area electron diffraction (SAED) pattern indicated that the product was pure polycrystalline cubic-phase {beta}-ZnS. The morphology and size of the as-synthesized product were determined by the transmission electron microscopy (TEM). The effects of some of the key reaction parameters (such as the ratio of surfactant to water, the reactant concentration and reaction temperature, etc.) had been explored in this paper. A growth mechanism of ZnS nanowires by micelle-template inducing reaction was also proposed.

  7. Photophysical behavior of a homologous series of amphiphilic hemicyanine dyes in thin AOT films

    NASA Astrophysics Data System (ADS)

    Gallos, L. K.; Stathatos, E.; Lianos, P.; Argyrakis, P.

    2002-01-01

    The photophysical behavior of a homologous series of amphiphilic hemicyanines, incorporated in thin films, made by dip-coating glass slides in bis(2-ethylhexyl)sulfosuccinate sodium salt (AOT) reverse micellar solutions, has been studied by absorption spectrophotometry and computer simulation techniques. At relatively high dye concentration, a narrow band in the absorption spectrum was observed, corresponding to aggregated species. Aggregates are of the H-type, displaying a hypsochromic shift in their absorption spectra, except for the shortest chain homolog. The growth of aggregates in films has been studied in relation with the [water]/[dye] and the [surfactant]/[dye] ratios. Simulation of the aggregate formation by extended dipole interaction in spherical reverse micelles and planar bilayer structures in combination with experimental data, revealed that the films are structured in microheterogeneous assemblies analogous to the reverse micelles found in the original solutions.

  8. Lipophilic porphyrin microparticles induced by AOT reverse micelles: a fluorescence lifetime imaging study.

    PubMed

    Togashi, Denisio M; Costa, Sílvia M B; Sobral, Abílio J F N

    2006-01-20

    Fluorescence Lifetime Imaging Microscopy (FLIM) technique was applied to investigate the fluorescence dynamics and structural features of large colloidal aggregates of meso-tetra(N-dodecyl-4-amino sulfonyl-phenyl)porphyrin (PC12) induced by Sodium 1,4-bis(2-ethyl hexyl)sulfosuccinate (AOT) reverse micelles. The aggregate's particle sizes (down to 1 microm) obtained from the confocal fluorescence images matched with the particle sizes measured in the images obtained from Scanning Electron Microscopy (SEM). The fluorescence decays for those aggregates in the micro spatial domain show triexponential fluorescence lifetimes (tau1 approximately 12 ns, tau2 approximately 3 ns and tau3 approximately 1 ns) which are independent of the aggregate's size. PMID:16154681

  9. Improving activity and stability of cutinase towards the anionic detergent AOT by complete saturation mutagenesis.

    PubMed

    Brissos, V; Eggert, T; Cabral, J M S; Jaeger, K-E

    2008-06-01

    Cutinase is an enzyme suitable for detergent applications as well as for organic synthesis in non-aqueous solvents. However, its inactivation in the presence of anionic surfactants is a problem which we have addressed by creating a complete saturation library. For this, the cutinase gene from Fusarium solani pisi was mutated to incorporate all 19 possible amino acid exchanges at each of the 214 amino acid positions. The resulting library was screened for active variants with improved stability in the presence of the anionic surfactant dioctyl sulfosuccinate sodium salt (AOT). Twenty-four sites in cutinase were discovered where amino acid replacements resulted in a 2-11-fold stability increase as compared to the wild-type enzyme. PMID:18424821

  10. Mediterranean aerosol typing by integrating three-wavelength lidar and sun photometer measurements.

    PubMed

    Perrone, M R; Burlizzi, P

    2016-07-01

    Backscatter lidar measurements at 355, 532, and 1064 nm combined with aerosol optical thicknesses (AOTs) from sun photometer measurements collocated in space and time were used to retrieve the vertical profiles of intensive and extensive aerosol parameters. Then, the vertical profiles of the Ångström coefficients for different wavelength pairs (Å(λ1, λ2, z)), the color ratio (CR(z)), the fine mode fraction (η(z)) at 532 nm, and the fine modal radius (R f (z)), which represent aerosol characteristic properties independent from the aerosol load, were used for typing the aerosol over the Central Mediterranean. The ability of the Ångström coefficients to identify the main aerosol types affecting the Central Mediterranean with the support of the backward trajectory analysis was first demonstrated. Three main aerosol types, which were designed as continental-polluted (CP), marine-polluted (MP), and desert-polluted (DP), were identified. We found that both the variability range and the vertical profile structure of the tested aerosol intensive parameters varied with the aerosol type. The variability range and the altitude dependence of the aerosol extinction coefficients at 355, 532, and 1064 nm, respectively, also varied with the identified aerosol types even if they are extensive aerosol parameters. DP, MP, and CP aerosols were characterized by the Å(532, 1064 nm) mean values ± 1 standard deviation equal to 0.5 ± 0.2, 1.1 ± 0.2, 1.6 ± 0.2, respectively. η(%) mean values ± 1SD were equal to 50 ± 10, 73 ± 7, and 86 ± 6 for DP, MP, and CP aerosols, respectively. The R f and CR mean values ± 1SD were equal to 0.16 ± 0.05 μm and 1.3 ± 0.3, respectively, for DP aerosols; to 0.12 ± 0.03 μm and 1.8 ± 0.4, respectively, for MP aerosols; and to 0.11 ± 0.02 μm and 1.7 ± 0.4, respectively, for CP aerosols. CP and DP aerosols were on average responsible for greater AOT and LR values, but

  11. Factors for inconsistent aerosol single scattering albedo between SKYNET and AERONET

    NASA Astrophysics Data System (ADS)

    Khatri, P.; Takamura, T.; Nakajima, T.; Estellés, V.; Irie, H.; Kuze, H.; Campanelli, M.; Sinyuk, A.; Lee, S.-M.; Sohn, B. J.; Pandithurai, G.; Kim, S.-W.; Yoon, S. C.; Martinez-Lozano, J. A.; Hashimoto, M.; Devara, P. C. S.; Manago, N.

    2016-02-01

    SKYNET and Aerosol Robotic Network (AERONET) retrieved aerosol single scattering albedo (SSA) values of four sites, Chiba (Japan), Pune (India), Valencia (Spain), and Seoul (Korea), were compared to understand the factors behind often noted large SSA differences between them. SKYNET and AERONET algorithms are found to produce nearly same SSAs for similarity in input data, suggesting that SSA differences between them are primarily due to quality of input data due to different calibration and/or observation protocols as well as difference in quality assurance criteria. The most plausible reason for high SSAs in SKYNET is found to be underestimated calibration constant for sky radiance (ΔΩ). The disk scan method (scan area: 1° × 1° area of solar disk) of SKYNET is noted to produce stable wavelength-dependent ΔΩ values in comparison to those determined from the integrating sphere used by AERONET to calibrate sky radiance. Aerosol optical thickness (AOT) difference between them can be the next important factor for their SSA difference, if AOTs between them are not consistent. Inconsistent values of surface albedo while analyzing data of SKYNET and AERONET can also bring SSA difference between them, but the effect of surface albedo is secondary. The aerosol nonsphericity effect is found to be less important for SSA difference between these two networks.

  12. Long-term variability of aerosol optical thickness in Eastern Europe over 2001-2014 according to the measurements at the Moscow MSU MO AERONET site with additional cloud and NO2 correction

    NASA Astrophysics Data System (ADS)

    Chubarova, N. Y.; Poliukhov, A. A.; Gorlova, I. D.

    2016-02-01

    The atmospheric aerosol properties were obtained within the framework of the AERONET program at the Moscow State University Meteorological Observatory (Moscow MSU MO) over the 2001-2014 period. The quality data control has revealed the necessity of additional cloud screening and NO2 correction. The application of additional cloud screening according to hourly visual cloud observations provides a decrease in monthly average aerosol optical thickness (AOT) at 500 nm of up to 0.03 compared with the standard data set. We also show that the additional NO2 correction of the AERONET version 2 data is needed in large megalopolis, like Moscow, with 12 million residents and NOx emission rates of about 100 kt yr-1. According to the developed method, we estimated monthly mean NO2 content, which provides an additional decrease of 0.01 for AOT at 340 nm, and of about 0.015 - for AOT at 380 and 440 nm. The ratios of NO2 optical thickness to AOT at 380 and 440 nm are about 5-6 % in summer and reach 15-20 % in winter when both factors have similar effects on UV irradiance. Seasonal cycle of AOT at 500 nm is characterized by a noticeable summer and spring maxima, and a minimum in winter conditions, changing from 0.08 in December and January up to 0.3 in August. The application of the additional cloud screening removes a local AOT maximum in February. Statistically significant negative trends in annual AOT for UV and mid-visible spectral range have been obtained both for average and 50 % quantile values. The pronounced negative changes were observed in most months with the rate of about -1-5 % yr-1 and could be attributed to the negative trends in emissions (E) of different aerosol precursors of about 135 Gg yr-2 in ESOx, 54 Gg yr-2 in ENMVOC, and slight negative changes in NOx over the European part of Russia. No significant influence of natural factors on temporal AOT variations has been revealed.

  13. New developments in the representation of Saharan dust sources in the aerosol-climate model ECHAM6-HAM2

    NASA Astrophysics Data System (ADS)

    Heinold, Bernd; Tegen, Ina; Schepanski, Kerstin; Banks, Jamie R.

    2016-02-01

    In the aerosol-climate model ECHAM6-HAM2, dust source activation (DSA) observations from Meteosat Second Generation (MSG) satellite are proposed to replace the original source area parameterization over the Sahara Desert. The new setup is tested in nudged simulations for the period 2007 to 2008. The evaluation is based on comparisons to dust emission events inferred from MSG dust index imagery, Aerosol Robotic Network (AERONET) sun photometer observations, and satellite retrievals of aerosol optical thickness (AOT).The model results agree well with AERONET measurements especially in terms of seasonal variability, and a good spatial correlation was found between model results and MSG-SEVIRI (Spinning-Enhanced Visible and InfraRed Imager) dust AOT as well as Multi-angle Imaging SpectroRadiometer (MISR) AOT. ECHAM6-HAM2 computes a more realistic geographical distribution and up to 20 % higher annual Saharan dust emissions, using the MSG-based source map. The representation of dust AOT is partly improved in the southern Sahara and Sahel. In addition, the spatial variability is increased towards a better agreement with observations depending on the season. Thus, using the MSG DSA map can help to circumvent the issue of uncertain soil input parameters.An important issue remains the need to improve the model representation of moist convection and stable nighttime conditions. Compared to sub-daily DSA information from MSG-SEVIRI and results from a regional model, ECHAM6-HAM2 notably underestimates the important fraction of morning dust events by the breakdown of the nocturnal low-level jet, while a major contribution is from afternoon-to-evening emissions.

  14. Development of the Ensemble Navy Aerosol Analysis Prediction System (ENAAPS) and its application of the Data Assimilation Research Testbed (DART) in support of aerosol forecasting

    NASA Astrophysics Data System (ADS)

    Rubin, Juli I.; Reid, Jeffrey S.; Hansen, James A.; Anderson, Jeffrey L.; Collins, Nancy; Hoar, Timothy J.; Hogan, Timothy; Lynch, Peng; McLay, Justin; Reynolds, Carolyn A.; Sessions, Walter R.; Westphal, Douglas L.; Zhang, Jianglong

    2016-03-01

    An ensemble-based forecast and data assimilation system has been developed for use in Navy aerosol forecasting. The system makes use of an ensemble of the Navy Aerosol Analysis Prediction System (ENAAPS) at 1 × 1°, combined with an ensemble adjustment Kalman filter from NCAR's Data Assimilation Research Testbed (DART). The base ENAAPS-DART system discussed in this work utilizes the Navy Operational Global Analysis Prediction System (NOGAPS) meteorological ensemble to drive offline NAAPS simulations coupled with the DART ensemble Kalman filter architecture to assimilate bias-corrected MODIS aerosol optical thickness (AOT) retrievals. This work outlines the optimization of the 20-member ensemble system, including consideration of meteorology and source-perturbed ensemble members as well as covariance inflation. Additional tests with 80 meteorological and source members were also performed. An important finding of this work is that an adaptive covariance inflation method, which has not been previously tested for aerosol applications, was found to perform better than a temporally and spatially constant covariance inflation. Problems were identified with the constant inflation in regions with limited observational coverage. The second major finding of this work is that combined meteorology and aerosol source ensembles are superior to either in isolation and that both are necessary to produce a robust system with sufficient spread in the ensemble members as well as realistic correlation fields for spreading observational information. The inclusion of aerosol source ensembles improves correlation fields for large aerosol source regions, such as smoke and dust in Africa, by statistically separating freshly emitted from transported aerosol species. However, the source ensembles have limited efficacy during long-range transport. Conversely, the meteorological ensemble generates sufficient spread at the synoptic scale to enable observational impact through the ensemble data

  15. Development of the Ensemble Navy Aerosol Analysis Prediction System (ENAAPS) and its application of the Data Assimilation Research Testbed (DART) in support of aerosol forecasting

    NASA Astrophysics Data System (ADS)

    Rubin, J. I.; Reid, J. S.; Hansen, J. A.; Anderson, J. L.; Collins, N.; Hoar, T. J.; Hogan, T.; Lynch, P.; McLay, J.; Reynolds, C. A.; Sessions, W. R.; Westphal, D. L.; Zhang, J.

    2015-10-01

    An ensemble-based forecast and data assimilation system has been developed for use in Navy aerosol forecasting. The system makes use of an ensemble of the Navy Aerosol Analysis Prediction System (ENAAPS) at 1° × 1°, combined with an Ensemble Adjustment Kalman Filter from NCAR's Data Assimilation Research Testbed (DART). The base ENAAPS-DART system discussed in this work utilizes the Navy Operational Global Analysis Prediction System (NOGAPS) meteorological ensemble to drive offline NAAPS simulations coupled with the DART Ensemble Kalman Filter architecture to assimilate bias-corrected MODIS Aerosol Optical Thickness (AOT) retrievals. This work outlines the optimization of the 20-member ensemble system, including consideration of meteorology and source-perturbed ensemble members as well as covariance inflation. Additional tests with 80 meteorological and source members were also performed. An important finding of this work is that an adaptive covariance inflation method, which has not been previously tested for aerosol applications, was found to perform better than a temporally and spatially constant covariance inflation. Problems were identified with the constant inflation in regions with limited observational coverage. The second major finding of this work is that combined meteorology and aerosol source ensembles are superior to either in isolation and that both are necessary to produce a robust system with sufficient spread in the ensemble members as well as realistic correlation fields for spreading observational information. The inclusion of aerosol source ensembles improves correlation fields for large aerosol source regions such as smoke and dust in Africa, by statistically separating freshly emitted from transported aerosol species. However, the source ensembles have limited efficacy during long range transport. Conversely, the meteorological ensemble produces sufficient spread at the synoptic scale to enable observational impact through the ensemble data

  16. Atmospheric effects on insolation in the Brazilian Amazon: Observed modification of solar radiation by clouds and smoke and derived single scattering albedo of fire aerosols

    NASA Astrophysics Data System (ADS)

    Schafer, J. S.; Holben, B. N.; Eck, T. F.; Yamasoe, M. A.; Artaxo, P.

    2002-10-01

    Five aerosol and solar flux monitoring sites were established in Brazil for the Large Scale Biosphere-Atmosphere Experiment in Amazônia (LBA) project. The first two sites were developed in the states of Rondonia and Mato Grosso in January 1999, while the others were initiated in September 1999 in Amazonas, Para, and near Brasilia (later relocated to Acre). Daily insolation [photosynthetically active radiation (PAR) and total solar] for 1999 and 9 months of 2000 was determined from flux measurements, and the daily fraction of theoretical cloud-free, background-aerosol insolation, fB(day), was evaluated for each site. Observed daily shortfall (MJ m-2 d-1) of PAR insolation due to clouds and aerosols (relative to modeled values for background aerosol), and the instantaneous reductions of PAR irradiance due to high aerosol optical thickness (AOT) smoke events are presented for 1999 at Alta Floresta. The ratio of PAR flux to total solar flux (PAR fraction) was examined for all atmospheric conditions during 1999, and the observed dependence of this parameter on column water vapor and smoke AOT was quantified. No significant relationship with cloud amount (as quantified) was found. Instantaneous PAR irradiance measurements and concurrent, cloud-cleared aerosol data from collocated CIMEL sunphotometers were used with a radiative transfer model to investigate the optical properties of smoke aerosols during the burning season. In particular, the single scattering albedo (SSA) was evaluated in the PAR spectral range for AOT440 nm values ranging from 0.8 to 3.0. These estimates were compared with the operational retrievals of the same parameter from algorithms developed by AERONET for CIMEL sunphotometer radiance measurements.

  17. An evaluation of the impact of aerosol particles on weather forecasts from a biomass burning aerosol event over the Midwestern United States: observational-based analysis of surface temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Jianglong; Reid, Jeffrey S.; Christensen, Matthew; Benedetti, Angela

    2016-05-01

    A major continental-scale biomass burning smoke event from 28-30 June 2015, spanning central Canada through the eastern seaboard of the United States, resulted in unforecasted drops in daytime high surface temperatures on the order of 2-5 °C in the upper Midwest. This event, with strong smoke gradients and largely cloud-free conditions, provides a natural laboratory to study how aerosol radiative effects may influence numerical weather prediction (NWP) forecast outcomes. Here, we describe the nature of this smoke event and evaluate the differences in observed near-surface air temperatures between Bismarck (clear) and Grand Forks (overcast smoke), to evaluate to what degree solar radiation forcing from a smoke plume introduces daytime surface cooling, and how this affects model bias in forecasts and analyses. For this event, mid-visible (550 nm) smoke aerosol optical thickness (AOT, τ) reached values above 5. A direct surface cooling efficiency of -1.5 °C per unit AOT (at 550 nm, τ550) was found. A further analysis of European Centre for Medium-Range Weather Forecasts (ECMWF), National Centers for Environmental Prediction (NCEP), United Kingdom Meteorological Office (UKMO) near-surface air temperature forecasts for up to 54 h as a function of Moderate Resolution Imaging Spectroradiometer (MODIS) Dark Target AOT data across more than 400 surface stations, also indicated the presence of the daytime aerosol direct cooling effect, but suggested a smaller aerosol direct surface cooling efficiency with magnitude on the order of -0.25 to -1.0 °C per unit τ550. In addition, using observations from the surface stations, uncertainties in near-surface air temperatures from ECMWF, NCEP, and UKMO model runs are estimated. This study further suggests that significant daily changes in τ550 above 1, at which the smoke-aerosol-induced direct surface cooling effect could be comparable in magnitude with model uncertainties, are rare events on a global scale. Thus, incorporating

  18. Seasonal variation of spherical aerosols distribution in East Asia based on ground and space Lidar observation and a Chemical transport model

    NASA Astrophysics Data System (ADS)

    Hara, Y.; Yumimoto, K.; Uno, I.; Shimizu, A.; Sugimoto, N.; Ohara, T.

    2009-12-01

    The anthropogenic aerosols largely impact on not only human health but also global climate system, therefore air pollution in East Asia due to a rapid economic growth has been recognized as a significant environmental problem. Several international field campaigns had been conducted to elucidate pollutant gases, aerosols characteristics and radiative forcing in East Asia. (e.g., ACE-Asia, TRACE-P, ADEC, EAREX 2005). However, these experiments were mainly conducted in springtime, therefore seasonal variation of aerosols distribution has not been clarified well yet. National Institute for Environmental Studies (NIES) has been constructing a lidar networks by automated dual wavelength / polarization Mie-lidar systems to observe the atmospheric environment in Asian region since 2001. Furthermore, from June 2006, space-borne backscatter lidar, Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), onboard NASA/CALIPSO satellite, measures continuous global aerosol and cloud vertical distribution with very high spatial resolution. In this paper, we will show the seasonal variation of aerosols distribution in East Asia based on the NIES lidar network observation, Community Multi-scale Air Quality Modeling System (CMAQ) chemical transport model simulation and CALIOP observation over the period from July 2006 to December 2008. We found that CMAQ result explains the typical seasonal aerosol characteristics by lidar observations. For example, CMAQ and ground lidar showed a summertime peak of aerosol optical thickness (AOT) at Beijing, an autumn AOT peak at Guangzhou and summertime AOT trough at Hedo, Okinawa. These characteristics are mainly controlled by seasonal variations of Asian summer/winter monsoon system. We also examined the CMAQ seasonal average aerosol extinction profiles with ground lidar and CALIOP extinction data. These comparisons clarified that the CMAQ reproduced the observed aerosol layer depth well in the downwind region. Ground lidar and CALIOP seasonal

  19. A novel method to retrieve Aerosol Optical Thickness from high-resolution optical satellite images using an extended version of the Haze Optimized Transform (HOTBAR)

    NASA Astrophysics Data System (ADS)

    Wilson, Robin; Milton, Edward; Nield, Joanna

    2016-04-01

    Aerosol Optical Thickness (AOT) data has many important applications including atmospheric correction of satellite imagery and monitoring of particulate matter air pollution. Current data products are generally available at a kilometre-scale resolution, but many applications require far higher resolutions. For example, particulate matter concentrations vary on a metre-scale, and thus data products at a similar scale are required to provide accurate assessments of particle densities and allow effective monitoring of air quality and analysis of local air quality effects on health. A novel method has been developed which retrieves per-pixel AOT values from high-resolution (~30m) satellite data. This method is designed to work over a wide range of land covers - including both bright and dark surfaces - and requires only standard visible and near-infrared data, making it applicable to a range of data from sensors such as Landsat, SPOT and Sentinel-2. The method is based upon an extension of the Haze Optimized Transform (HOT). The HOT was originally designed for assessing areas of thick haze in satellite imagery by calculating a 'haziness' value for each pixel in an image as the distance from a 'Clear Line' in feature space, defined by the high correlation between visible bands. Here, we adapt the HOT method and use it to provide AOT data instead. Significant extensions include Monte Carlo estimation of the 'Clear Line', object-based correction for land cover, and estimation of AOT from the haziness values through radiative transfer modelling. This novel method will enable many new applications of AOT data that were impossible with previously available low-resolution data, and has the potential to contribute significantly to our understanding of the air quality on health, the accuracy of satellite image atmospheric correction and the role of aerosols in the climate system.

  20. Perturbation mechanism and phase transition of AOT aggregates in the Fe(II)[batho(SO 3) 2] 3 - catalyzed aqueous Belousov-Zhabotinsky reaction

    NASA Astrophysics Data System (ADS)

    Jahan, Rumana A.; Suzuki, Kosuke; Mahara, Hitoshi; Nishimura, Satoshi; Iwatsubo, Takashi; Kaminaga, Akiko; Yamamoto, Yasuhiko; Yamaguchi, Tomohiko

    2010-01-01

    Surfactant AOT (sodium bis(2-ethylhexyl)sulfosuccinate) was introduced up to 200 mmol L -1 in the aqueous Belousov-Zhabotinsky (BZ) medium. Both the induction period (IP) and the oscillation period ( τ) of the BZ waves decreased significantly, whereas the wave velocity ( v) increased with the concentration of AOT. These tendencies were explained in terms of the perturbations to the FKN mechanism through the uptake of Br 2 and BrO2· into the hydrophobic core of AOT aggregates. In addition, the structures and the phase transition of AOT aggregates were suggested based on the measurement of surface tension and the correlation analysis of the IP, τ and v values.

  1. Bi-functional ion exchangers for enhanced performance of dye-sensitized solar cells.

    PubMed

    Kong, Eui-Hyun; Chang, Yong-June; Lim, Jongchul; Kim, Back-Hyun; Lee, Jung-Hoon; Kwon, Do-Kyun; Park, Taiho; Jang, Hyun Myung

    2013-07-28

    Ion exchange using aerosol OT (AOT) offers dye adsorption twice as fast as known methods. Moreover, it suppresses the dye-agglomeration that may cause insufficient dye-coverage on the photoelectrode surface. Consequently, its dual function of fast dye-loading and higher dye-coverage significantly improves the power conversion efficiency of dye-sensitized solar cells. PMID:23775416

  2. MODIS Observation of Aerosols over Southern Africa During SAFARI 2000: Data, Validation, and Estimation of Aerosol Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Ichoku, Charles; Kaufman, Yoram; Remer, Lorraine; Chu, D. Allen; Mattoo, Shana; Tanre, Didier; Levy, Robert; Li, Rong-Rong; Kleidman, Richard; Lau, William K. M. (Technical Monitor)

    2001-01-01

    Aerosol properties, including optical thickness and size parameters, are retrieved operationally from the MODIS sensor onboard the Terra satellite launched on 18 December 1999. The predominant aerosol type over the Southern African region is smoke, which is generated from biomass burning on land and transported over the southern Atlantic Ocean. The SAFARI-2000 period experienced smoke aerosol emissions from the regular biomass burning activities as well as from the prescribed burns administered on the auspices of the experiment. The MODIS Aerosol Science Team (MAST) formulates and implements strategies for the retrieval of aerosol products from MODIS, as well as for validating and analyzing them in order to estimate aerosol effects in the radiative forcing of climate as accurately as possible. These activities are carried out not only from a global perspective, but also with a focus on specific regions identified as having interesting characteristics, such as the biomass burning phenomenon in southern Africa and the associated smoke aerosol, particulate, and trace gas emissions. Indeed, the SAFARI-2000 aerosol measurements from the ground and from aircraft, along with MODIS, provide excellent data sources for a more intensive validation and a closer study of the aerosol characteristics over Southern Africa. The SAFARI-2000 ground-based measurements of aerosol optical thickness (AOT) from both the automatic Aerosol Robotic Network (AERONET) and handheld Sun photometers have been used to validate MODIS retrievals, based on a sophisticated spatio-temporal technique. The average global monthly distribution of aerosol from MODIS has been combined with other data to calculate the southern African aerosol daily averaged (24 hr) radiative forcing over the ocean for September 2000. It is estimated that on the average, for cloud free conditions over an area of 9 million square kin, this predominantly smoke aerosol exerts a forcing of -30 W/square m C lose to the terrestrial

  3. Signatures of semi-direct radiative forcing by absorbing aerosols in satellite observations and models

    NASA Astrophysics Data System (ADS)

    Wilcox, E. M.; Hosseinpour, F.; Colarco, P. R.

    2014-12-01

    Semi-direct radiative forcing of climate occurs when interactions between aerosols and radiative fluxes in the atmosphere yield a dynamical response in clouds. Semi-direct forcing is typically thought to be a positive radiative forcing whereby soot and biomass burning aerosols absorb sunlight and burn-off clouds. However, a negative semi-direct forcing is suspected in at least two regimes, the summertime Southeast Atlantic Ocean and the wintertime North Indian Ocean, where the heating profile by aerosol absorption by solar radiation is elevated above the elevation of the low clouds. Here we use a combination of satellite data and a model simulation to further characterize the signature of semi-direct radiative forcing in these two locations and elsewhere on the globe. We apply CERES albedos, Calipso profiles of aerosol extinction and cloud-top altitude, and a simulation with the Goddard Earth Observing System Model version 5 (GEOS-5) Earth system model with meteorology constrained by MERRA and an assimilation of MODIS AOT (MERRAero). to quantify the vertical heating profile by aerosols under clear and cloudy skies. We seek to determine: (1) where aerosol heating by soot and biomass burning aerosol is occurring; (2) where vertically in the column the heating is occurring relative to the observed level of low cloud development; and (3) whether the variations of albedo with aerosol forcing suggest a positive, negative, or inconclusive semi-direct radiative forcing.

  4. First retrieval of data regarding spatial distribution of Asian dust aerosol from the Geostationary Ocean Color Imager

    NASA Astrophysics Data System (ADS)

    Lee, Kwon Ho; Ryu, Joo Hyung; Ahn, Jae Hyun; Kim, Young Joon

    2012-12-01

    Aerosol optical thickness (AOT) was retrieved from the Geostationary Ocean Color Imager (GOCI) on board the Communication, Ocean, and Meteorological Satellite (COMS) for the first time. AOT values were retrieved over the ocean at a spatial scale of 0.5 × 0.5 km2 by using the look-up table (LUT)-based separation technique. The radiative transfer model (RTM) was used for different models of atmosphere-ocean environmental conditions, taking into account the realistic variability of scattering and absorption. Ocean surface properties affected by whitecaps and pigment content were also taken into account. The results show that the radiance observed by the GOCI amounts to only 5% of the radiation that penetrated the ocean and, consequently, 95% of the radiation is scattered in the atmosphere or reflected at the ocean surface in the visible wavelengths longer than 0.6 ìm. Within these wavelengths, radiance variations at the top of atmosphere (TOA) due to pigment variations are within 10%, while the radiance variation due to wind speed is considerably higher. For verification of GOCI-retrieved AOTs, comparison between GOCI and ground-based sunphotometer measurement at Gosan, Korea (126.10°E, 33.23°N)) showed good correlation (r = 0.99). The GOCI observations obtained by using the proposed technique showed promising results for the daily monitoring of atmospheric aerosol loading as well as being useful for environmental supervisory authorities.

  5. Mass spectrometry study of multiply negatively charged, gas-phase NaAOT micelles: how does charge state affect micellar structure and encapsulation?

    PubMed

    Fang, Yigang; Liu, Fangwei; Liu, Jianbo

    2013-01-01

    We report the formation and characterization of multiply negatively charged sodium bis(2-ethylhexyl) sulfosuccinate (NaAOT) aggregates in the gas phase, by electrospray ionization of methanol/water solution of NaAOT followed by detection using a guided-ion-beam tandem mass spectrometer. Singly and doubly charged aggregates dominate the mass spectra with the compositions of [Na(n-z)AOT(n)](z-) (n = 1-18 and z = 1-2). Solvation by water was detected only for small aggregates [Na(n-1)AOT(n)H(2)O](-) of n = 3-9. Incorporation of glycine and tryptophan into [Na(n-z)AOT(n)](z-) aggregates was achieved, aimed at identifying effects of guest molecule hydrophobicity on micellar solubilization. Only one glycine molecule could be incorporated into each [Na(n-z)AOT(n)](z-) of n ≥ 7, and at most two glycine molecules could be hosted in that of n ≥ 13. In contrast to glycine, up to four tryptophan molecules could be accommodated within single aggregates of n ≥ 6. However, deprotonation of tryptophan significantly decrease its affinity towards aggregates. Collision-induced dissociation (CID) was carried out for mass-selected aggregate ions, including measurements of product ion mass spectra for both empty and amino acid-containing aggregates. CID results provide a probe for aggregate structures, surfactant-solute interactions, and incorporation sites of amino acids. The present data was compared with mass spectrometry results of positively charged [Na(n+z)AOT(n)](z+) aggregates. Contrary to their positive analogues, which form reverse micelles, negatively charged aggregates may adopt a direct micelle-like structure with AOT polar heads exposed and amino acids being adsorbed near the micellar outer surface. PMID:23247969

  6. Global Aerosols

    Atmospheric Science Data Center

    2013-04-19

    ... sizes and from multiple sources, including biomass burning, mineral dust, sea salt and regional industrial pollution. A color scale is ... desert source region. Deserts are the main sources of mineral dust, and MISR obtains aerosol optical depth at visible wavelengths ...

  7. 12 CFR 563b.240 - What must I submit to OTS after the members' meeting?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Vote by Members § 563b.240 What must I... the following information with OTS: (1) A certified copy of each adopted resolution on the...

  8. 12 CFR 563b.240 - What must I submit to OTS after the members' meeting?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Vote by Members § 563b.240 What must I... the following information with OTS: (1) A certified copy of each adopted resolution on the...

  9. 12 CFR 563b.240 - What must I submit to OTS after the members' meeting?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Vote by Members § 563b.240 What must I... the following information with OTS: (1) A certified copy of each adopted resolution on the...

  10. 12 CFR 563b.240 - What must I submit to OTS after the members' meeting?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Vote by Members § 563b.240 What must I... the following information with OTS: (1) A certified copy of each adopted resolution on the...

  11. 12 CFR 563b.240 - What must I submit to OTS after the members' meeting?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Vote by Members § 563b.240 What must I... the following information with OTS: (1) A certified copy of each adopted resolution on the...

  12. Impact of aerosols on the OMI tropospheric NO2 retrievals over industrialized regions: how accurate is the aerosol correction of cloud-free scenes via a simple cloud model?

    NASA Astrophysics Data System (ADS)

    Chimot, J.; Vlemmix, T.; Veefkind, J. P.; de Haan, J. F.; Levelt, P. F.

    2016-02-01

    The Ozone Monitoring Instrument (OMI) has provided daily global measurements of tropospheric NO2 for more than a decade. Numerous studies have drawn attention to the complexities related to measurements of tropospheric NO2 in the presence of aerosols. Fine particles affect the OMI spectral measurements and the length of the average light path followed by the photons. However, they are not explicitly taken into account in the current operational OMI tropospheric NO2 retrieval chain (DOMINO - Derivation of OMI tropospheric NO2) product. Instead, the operational OMI O2 - O2 cloud retrieval algorithm is applied both to cloudy and to cloud-free scenes (i.e. clear sky) dominated by the presence of aerosols. This paper describes in detail the complex interplay between the spectral effects of aerosols in the satellite observation and the associated response of the OMI O2 - O2 cloud retrieval algorithm. Then, it evaluates the impact on the accuracy of the tropospheric NO2 retrievals through the computed Air Mass Factor (AMF) with a focus on cloud-free scenes. For that purpose, collocated OMI NO2 and MODIS (Moderate Resolution Imaging Spectroradiometer) Aqua aerosol products are analysed over the strongly industrialized East China area. In addition, aerosol effects on the tropospheric NO2 AMF and the retrieval of OMI cloud parameters are simulated. Both the observation-based and the simulation-based approach demonstrate that the retrieved cloud fraction increases with increasing Aerosol Optical Thickness (AOT), but the magnitude of this increase depends on the aerosol properties and surface albedo. This increase is induced by the additional scattering effects of aerosols which enhance the scene brightness. The decreasing effective cloud pressure with increasing AOT primarily represents the shielding effects of the O2 - O2 column located below the aerosol layers. The study cases show that the aerosol correction based on the implemented OMI cloud model results in biases

  13. North-south cross sections of the vertical aerosol distribution over the Atlantic Ocean from multiwavelength Raman/polarization lidar during Polarstern cruises

    PubMed Central

    Kanitz, T; Ansmann, A; Engelmann, R; Althausen, D

    2013-01-01

    Shipborne aerosol lidar observations were performed aboard the research vessel Polarstern in 2009 and 2010 during three north-south cruises from about 50°N to 50°S. The aerosol data set provides an excellent opportunity to characterize and contrast the vertical aerosol distribution over the Atlantic Ocean in the polluted northern and relatively clean southern hemisphere. Three case studies, an observed pure Saharan dust plume, a Patagonian dust plume east of South America, and a case of a mixed dust/smoke plume west of Central Africa are exemplarily shown and discussed by means of their optical properties. The meridional transatlantic cruises were used to determine the latitudinal cross section of the aerosol optical thickness (AOT). Profiles of particle backscatter and extinction coefficients are presented as mean profiles for latitudinal belts to contrast northern- and southern-hemispheric aerosol loads and optical effects. Results of lidar observations at Punta Arenas (53°S), Chile, and Stellenbosch (34°S), South Africa, are shown and confirm the lower frequency of occurrence of free-tropospheric aerosol in the southern hemisphere than in the northern hemisphere. The maximum latitudinal mean AOT of 0.27 was found in the northern tropics (0– 15°N) in the Saharan outflow region. Marine AOT is typically 0.05 ± 0.03. Particle optical properties are presented separately for the marine boundary layer and the free troposphere. Concerning the contrast between the anthropogenically influenced midlatitudinal aerosol conditions in the 30– 60°N belt and the respective belt in the southern hemisphere over the remote Atlantic, it is found that the AOT and extinction coefficients for the vertical column from 0–5km (total aerosol column) and 1–5km height (lofted aerosol above the marine boundary layer) are a factor of 1.6 and 2 higher at northern midlatitudes than at respective southern midlatitudes, and a factor of 2.5 higher than at the clean marine southern

  14. OT2_ccodella_2: Where is chlorine in shocked regions?

    NASA Astrophysics Data System (ADS)

    Codella, C.

    2011-09-01

    As part of the GT Herschel Program CHESS we detected for the first time hydrogen chlorine in a protostellar shock, L1157-B1 (Codella et al. 2011). One of the most surprising results of this work was the lack of enhancement in the abundance of HCl with respect to dense interstellar clouds, implying that HCl is not enhanced by the passage of a shock. This means that either chlorine is not sputtered during the passage of the shock (unlikely as Si is sputtered) or that HCl is not the main reservoir of clorine in shocked regions (unlike in dense interstellar clouds). In this proposal we propose to observe HCl in a sample of shocked regions in order to determine whether this result is unique to L1157-B1. We stress that given the weakness of the HCl emission in shocks and the strong atmospheric water absorption at the requested frequency (626 GHz), the present experiment cannot be reasonably performed from ground, making of Herschel OT2 the last chance to reach the present goals.

  15. Desert Dust Aerosol Air Mass Mapping in the Western Sahara, Using Particle Properties Derived from Space-Based Multi-Angle Imaging

    NASA Technical Reports Server (NTRS)

    Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Esselborn, Michael; Fiebig, Marcus; Heese, Birgit; Knippertz, Peter; Mueller, Detlef; Schladitz, Alexander; Von Hoyningen-Huene, Wolfgang

    2008-01-01

    Coincident observations made over the Moroccan desert during the Sahara mineral dust experiment (SAMUM) 2006 field campaign are used both to validate aerosol amount and type retrieved from multi-angle imaging spectroradiometer (MISR) observations, and to place the suborbital aerosol measurements into the satellite s larger regional context. On three moderately dusty days during which coincident observations were made, MISR mid-visible aerosol optical thickness (AOT) agrees with field measurements point-by-point to within 0.05 0.1. This is about as well as can be expected given spatial sampling differences; the space-based observations capture AOT trends and variability over an extended region. The field data also validate MISR s ability to distinguish and to map aerosol air masses, from the combination of retrieved constraints on particle size, shape and single-scattering albedo. For the three study days, the satellite observations (1) highlight regional gradients in the mix of dust and background spherical particles, (2) identify a dust plume most likely part of a density flow and (3) show an aerosol air mass containing a higher proportion of small, spherical particles than the surroundings, that appears to be aerosol pollution transported from several thousand kilometres away.

  16. Effects of Hypergravity Exposure on Plasma Oxytocin (OT) Concentrations in Pregnant and Lactating Rat Dams

    NASA Technical Reports Server (NTRS)

    Baer, Lisa A.; Wade, Charles E.; Plaut, Karen; Ronca, April E.; Dalton, Bonnie (Technical Monitor)

    2002-01-01

    From pregnancy to weaning there is a progressive elevation of plasma oxytocin (OT) levels associated with nursing activity, irrespective of litter size. In the present study, we analyzed the effects of continuous 1.5G, 1.75G and 2.0G hypergravity exposure on OT plasma concentration in prepartum (Gestation Day 20) (G20) and lactating (Postnatal day) (P10) rat dams. For this study, litter size was controlled with a yoking procedure established in our lab where individual control litters were yoked-matched to individual hypergravity litters. We reviewed all data at hypergravity irrespective of gravitational level and compared the values with the controls in both G20 (HG, n=15;SC, n=9) and P10 (HG, n=21;SC, n=16). Results showed that over time, we did observe the expected OT increase in both groups. In G20 dams, measurement of OT concentrations showed no significance. However, at P10, measurements of OT concentrations suggest a reduction of about 20% compared to established controls in our laboratory, 0.9+/-0.09 ng/ml for the controls and 0.7+/-0.06 ng/ml for centrifuged animals (p<0.02). These data suggest that exposure to centrifugation may reduce OT levels during lactation. When these plasma samples were obtained, the dams were removed from the litters, and values were not adjusted for the size of the litters. The reduction in OT with centrifugation may reflect a decrease in nursing activity or a decreased responsiveness of the mammary hypothalamic axis. In addition, we have analyzed data on plasma prolactin concentrations and mammary gland development, which may give additional insight to the results of our OT measurements.

  17. Real structure of formamide entrapped by AOT nonaqueous reverse micelles: FT-IR and 1H NMR studies.

    PubMed

    Correa, N Mariano; Pires, Paulo Augusto R; Silber, Juana J; El Seoud, Omar A

    2005-11-10

    Noninvasive techniques such as FT-IR and (1)H NMR spectroscopy have been employed to investigate the solubilization of formamide, FA, and its aqueous solution, FA-water, by sodium 1,4-bis(2-ethylhexyl)sulfosuccinate, AOT, in heptane or isooctane reverse micelles, respectively. Partially deuterated FA (FADH) was used in the FT-IR experiments and nu(OD), n(ND) were analyzed. Also, the nu(C=O) band of FA was investigated. For AOT, the changes of the SO(3)(-) group's symmetric, nu(s), and asymmetric, nu(a), bands were also studied. The results are showing that FA is interacting strongly with the Na+ counterions of the surfactant through electrostatic interactions maintaining their hydrogen bond network present in the FA bulk. Accordingly, partially deuterated FA is "frozen" inside the aggregates and it is possible to detect, by FT-IR technique, the cis and trans isomers. Curve fitting of the nu(OD) (in the FA-water mixture) band requires use of two peaks because the band is asymmetric, not because the solubilizate molecules are present in layers of different structure. The chemical shifts of the (1)H bound to N and C of FA were studied by (1)H NMR. The comparison of the chemical shift of AOT in reverse micelles with FA and the FA-water mixture in the polar core of the aggregate shows that there is a strong preferential solvation of Na+ by FA (through electrostatic interaction) and the AOT's sulfonate group by water (through hydrogen bond interaction). PMID:16853748

  18. Comparing concentration-based (AOT40) and stomatal uptake (PODY) metrics for ozone risk assessment to European forests.

    PubMed

    Anav, Alessandro; De Marco, Alessandra; Proietti, Chiara; Alessandri, Andrea; Dell'Aquila, Alessandro; Cionni, Irene; Friedlingstein, Pierre; Khvorostyanov, Dmitry; Menut, Laurent; Paoletti, Elena; Sicard, Pierre; Sitch, Stephen; Vitale, Marcello

    2016-04-01

    Tropospheric ozone (O3 ) produces harmful effects to forests and crops, leading to a reduction of land carbon assimilation that, consequently, influences the land sink and the crop yield production. To assess the potential negative O3 impacts to vegetation, the European Union uses the Accumulated Ozone over Threshold of 40 ppb (AOT40). This index has been chosen for its simplicity and flexibility in handling different ecosystems as well as for its linear relationships with yield or biomass loss. However, AOT40 does not give any information on the physiological O3 uptake into the leaves since it does not include any environmental constraints to O3 uptake through stomata. Therefore, an index based on stomatal O3 uptake (i.e. PODY), which describes the amount of O3 entering into the leaves, would be more appropriate. Specifically, the PODY metric considers the effects of multiple climatic factors, vegetation characteristics and local and phenological inputs rather than the only atmospheric O3 concentration. For this reason, the use of PODY in the O3 risk assessment for vegetation is becoming recommended. We compare different potential O3 risk assessments based on two methodologies (i.e. AOT40 and stomatal O3 uptake) using a framework of mesoscale models that produces hourly meteorological and O3 data at high spatial resolution (12 km) over Europe for the time period 2000-2005. Results indicate a remarkable spatial and temporal inconsistency between the two indices, suggesting that a new definition of European legislative standard is needed in the near future. Besides, our risk assessment based on AOT40 shows a good consistency compared to both in-situ data and other model-based datasets. Conversely, risk assessment based on stomatal O3 uptake shows different spatial patterns compared to other model-based datasets. This strong inconsistency can be likely related to a different vegetation cover and its associated parameterizations. PMID:26492093

  19. Effect of alpha-lactalbumin on the phase behavior of AOT-brine-isooctane mixtures: role of charge interactions.

    PubMed

    Shimek, Justin W; Rohloff, Catherine M; Goldberg, Jessica; Dungan, Stephanie R

    2005-06-21

    We have found that both electrostatic and hydrophobic interactions are involved in the ability of the protein alpha-lactalbumin (alpha-LA) to affect the self-assembly of the anionic surfactant sodium bis(ethylhexyl) sulfosuccinate (AOT, 3.5 wt %) in equivolume mixtures of organic and aqueous solutions. The composition and size of AOT phase structures that form in the presence of 0.35 wt % protein were evaluated as a function of pH and ionic strength. In the absence of protein, AOT forms water-in-oil microemulsion droplets for all pH and salt concentrations studied here. The presence of the protein in the water-in-oil microemulsion phase boosts water solubilization and droplet size, as the spontaneous curvature of the surfactant interface becomes less negative. Aggregates of protein, surfactant, and oil also form in the water-continuous phase. The size and composition of structures in both phases can be tuned in the presence of protein by varying the pH and ionic strength. alpha-LA induces the appearance of an anisotropic surfactant phase at pH <5.8. At intermediate salt concentrations, a third isotropic, viscous aqueous phase appears that contains 55-60% of the protein, 10-14% of the surfactant, and significant amounts of oil. Circular dichroism and fluorescence spectroscopy indicate that the protein contains enhanced alpha-helical secondary structure when self-assembling with surfactant, and has a loosened tertiary structure. The protein does not interact with the surfactant as an unfolded random coil. Although the conformation of alpha-LA in aqueous salt solutions is known to depend on pH, when self-assembling with AOT the protein adopts a structure whose features are quite pH insensitive, and likely reflect an intrinsic interaction with the interface. PMID:15952844

  20. An Investigation of Dust Aerosols and Atmospheric Profiles Associated with North Atlantic Hurricanes Using Multi-Sensor Measurements

    NASA Astrophysics Data System (ADS)

    Kamal, Mohammed Mostafa

    MODerate resolution Imaging Spectroradiometer (MODIS) Aerosol Optical Thickness (AOT) and the Atmospheric Infrared Sounder (AIRS) atmospheric profiles (temperature and moisture) Level 2 products are studied to investigate dust aerosol impacts on hurricanes through spatial analysis for four hurricanes Isabel (2003), Frances (2004), Katrina (2005) and Helene (2006). Spatial regions were selected based on two concentric circles (an annulus) and segmented by left and right regions of 180° each around the hurricane's eye. Statistical relationships between MODIS AOT, AIRS temperature and percent relative humidity (RH) among these four hurricanes is presented. The variation of temperature and RH values represented in static-left, static-right, dynamic-left and dynamic-right for the 500 mb, 700 mb and 850 mb pressure levels were analyzed to determine the impacts of dust aerosols on temperature and RH. For the four hurricanes' average, AOT was found highest in Helene as opposed to (0.27) Isabel (0.23), Frances (0.18) and Katrina (0.16). Dust aerosols showed negative impacts on the atmospheric moisture levels and positive on the temperature. Additionally, a systematic multivariate analysis of MODIS aerosol retrievals over the North Atlantic spanning 7 hurricane seasons combined with Statistical Hurricane Intensity Prediction Scheme (SHIPS) parameters is presented. My focus is on investigating the effects of 5 categories that include aerosol, wind, relative humidity, shear, and temperature on hurricane intensities. The primary goal is to be able to explain the same physical phenomena equally well by significantly reducing the number of parameters employed in the statistical analysis. Five categories which include, wind, aerosol, shear, relative humidity, and temperature components were established by reducing 56 variables to 20. Aerosol, wind, humidity, shear, and temperature were all contributing factors in the regression equation with the ranking for the contribution found

  1. Intramolecular charge transfer reaction, polarity, and dielectric relaxation in AOT/water/heptane reverse micelles: pool size dependence.

    PubMed

    Biswas, Ranjit; Rohman, Nashiour; Pradhan, Tuhin; Buchner, Richard

    2008-08-01

    Intramolecular charge transfer (ICT) reaction in a newly synthesized molecule, of 4-(1-morpholenyl) benzonitrile (M6C), in AOT/water/heptane reverse micelles at different pool sizes has been studied by using steady-state and time-resolved fluorescence emission spectroscopy. The pool size dependences of the reaction equilibrium constant and reaction rate have been explained in terms of the average polarity of the confined solvent pools estimated from the fluorescence emission Stokes shift of a nonreactive probe, coumarin 153, dissolved in these microemulsions. The complex permittivity measurements in the frequency range 0.01AOT concentrations (0.1AOT headgroup and n-heptane. The reorientation of these interfacial water molecules is probably responsible for the nanosecond component observed in numerous polar solvation dynamics experiments in these reverse micelles. Subsequently, the estimated polarity and the measured reorientational time scale have been used to explain the dramatic slowing down of the ICT reaction rate and its dependence on pool size in these confined environments. PMID:18630864

  2. The forward and backward transport processes in the AOT/hexane reversed micellar extraction of soybean protein.

    PubMed

    Chen, Jun; Chen, Fengliang; Wang, Xianchang; Zhao, Xiaoyan; Ao, Qiang

    2014-10-01

    Soybean protein was taken as a model protein to investigate two aspects of the protein extraction by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles: (1) the forward protein extraction from the solid state, and the effect of pH, AOT concentration, alcohol and water content (W0) on the transfer efficiency; (2) the back-transfer, the capability of the protein to be recovered from the micellar solution. The experimental results led to the conclusion that the highest forward extraction efficiency of soybean protein was reached at AOT concentration 180 mmol l(-1), aqueous pH 7.0, KCl concentration 0.05 mol l(-1), 0.5 % (v/v) alcohol, W0 18. Under these conditions, the forward extraction efficiency of soybean protein achieved 70.1 %. It was noted that the percentage of protein back extraction depended on the salt concentration and pH value. Around 92 % of protein recovery was obtained after back extraction. PMID:25328237

  3. Spatial Aspects of Multi-Sensor Data Fusion: Aerosol Optical Thickness

    NASA Technical Reports Server (NTRS)

    Leptoukh, Gregory; Zubko, V.; Gopalan, A.

    2007-01-01

    The Goddard Earth Sciences Data and Information Services Center (GES DISC) investigated the applicability and limitations of combining multi-sensor data through data fusion, to increase the usefulness of the multitude of NASA remote sensing data sets, and as part of a larger effort to integrate this capability in the GES-DISC Interactive Online Visualization and Analysis Infrastructure (Giovanni). This initial study focused on merging daily mean Aerosol Optical Thickness (AOT), as measured by the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard the Terra and Aqua satellites, to increase spatial coverage and produce complete fields to facilitate comparison with models and station data. The fusion algorithm used the maximum likelihood technique to merge the pixel values where available. The algorithm was applied to two regional AOT subsets (with mostly regular and irregular gaps, respectively) and a set of AOT fields that differed only in the size and location of artificially created gaps. The Cumulative Semivariogram (CSV) was found to be sensitive to the spatial distribution of gap areas and, thus, useful for assessing the sensitivity of the fused data to spatial gaps.

  4. Effect of photochemical self-action of carbon-containing aerosol: Wildfires

    NASA Astrophysics Data System (ADS)

    Konovalov, I. B.; Berezin, E. V.; Beekmann, M.

    2016-05-01

    It has been shown by numerical simulation that the rate of formation of secondary organic aerosols (SOAs) in smoke plumes caused by vegetation and peat fires under real conditions can significantly depend on the aerosol optical thickness (AOT). The AOT determines the photodissociation rate and hydroxyl radical concentration, which in turn determines the rate of SOA generation as a result of oxidation of semivolatile organic compounds. Quantitative analysis has been carried out for the situation that took place in European Russia during the 2010 Russian wildfires. The state-of-the-art 3D chemical transport model is used in this study; the simulations are optimized and validated using the data of monitoring of the particulate matter in the Moscow region and Finland. The findings indicate that it is important to allow for this effect in studies focused on the analysis and prediction of air pollution due to wildfires, as well as climate and weather studies, whose results may depend on the assumptions about the content and properties of atmospheric carbon-containing aerosol.

  5. Kinetics and mechanism of the cutinase-catalyzed transesterification of oils in AOT reversed micellar system.

    PubMed

    Badenes, Sara M; Lemos, Francisco; Cabral, Joaquim M S

    2011-11-01

    The kinetics of the enzymatic transesterification between a mixture of triglycerides (oils) and methanol for biodiesel production in a bis(2-ethylhexyl) sodium sulfosuccinate (AOT)/isooctane reversed micellar system, using recombinant cutinase from Fusarium solani pisi as a catalyst, was investigated. In order to describe the results that were obtained, a mechanistic scheme was proposed, based on the literature and on the experimental data. This scheme includes the following reaction steps: the formation of the active enzyme-substrate complex, the addition of an alcohol molecule to the complex followed by the separation of a molecule of the fatty acid alkyl ester and a glycerol moiety, and release of the active enzyme. Enzyme inhibition and deactivation effects due to methanol and glycerol were incorporated in the model. This kinetic model was fitted to the concentration profiles of the fatty acid methyl esters (the components of biodiesel), tri-, di- and monoglycerides, obtained for a 24 h transesterification reaction performed in a stirred batch reactor under different reaction conditions of enzyme and initial substrates concentration. PMID:21739170

  6. Micellar interactions in water-AOT based droplet microemulsions containing hydrophilic and amphiphilic polymers

    NASA Astrophysics Data System (ADS)

    Appel, Markus; Spehr, Tinka Luise; Wipf, Robert; Moers, Christian; Frey, Holger; Stühn, Bernd

    2013-11-01

    We investigate the influence of addition of hydrophilic and amphiphilic polymer on percolation behavior and micellar interactions in AOT-based water-in-oil droplet microemulsions. We focus on two series of samples having constant molar water to surfactant ratio W = 20 and constant droplet volume fraction Φ = 30%, respectively. From dielectric spectroscopy experiments, we extract the bending rigidity of the surfactant shell by percolation temperature measurements. Depending on droplet size, we find stabilization and destabilization of the surfactant shell upon addition of hydrophilic poly(ethylene glycol) (PEG) (Mn = 3100 g mol-1) and amphiphilic poly(styrene)-b-poly(ethylene glycol) copolymer with comparable length of the hydrophilic block. Complementary small angle X-ray scattering experiments corroborate the finding of stabilization for smaller droplets and destabilization of larger droplets. Subsequent analysis of dielectric spectra enables us to extract detailed information about micellar interactions and clustering by evaluating the dielectric high frequency shell relaxation. We interpret the observed results as a possible modification of the inter-droplet charge transfer efficiency by addition of PEG polymer, while the amphiphilic polymer shows a comparable, but dampened effect.

  7. Thermal deactivation kinetics of Pseudomonas fluorescens lipase entrapped in AOT/isooctane reverse micelles.

    PubMed

    Park, Kyung Min; Kwon, Chang Woo; Choi, Seung Jun; Son, Young-Hwan; Lim, Seokwon; Yoo, Yoonjung; Chang, Pahn-Shick

    2013-10-01

    Thermostability of the lipase (EC 3.1.1.3) was found to be increased by the enzyme-entrapment in 50 mM AOT/isooctane reverse micelles. The half-life (15.75 h) of Pseudomonas fluorescens lipase entrapped in reverse micelles at 70 °C was 9.72- and 11.41-fold longer than those solubilized in a glycerol pool or in 10 mM phosphate buffer (pH 8.0), respectively. The enzyme deactivation model considering a two-step series-type was employed, and deactivation constants for the second step (k₂) at all temperatures were drastically decreased after the lipase was entrapped in reverse micelles. In particular, k₂ (0.0354 h⁻¹) at 70 °C in reverse micelles was 12.33- and 13.14-fold lower than in a glycerol pool or in the phosphate buffer, respectively. The deactivation energies (from k₁, k₂) for the lipase entrapped in the reverse micelles, solubilized in a glycerol pool, or in the aqueous buffer were 7.51, 26.35 kcal/mol, 5.93, 21.08 kcal/mol, and 5.53, 17.57 kcal/mol, respectively. PMID:23984828

  8. Spraying enzymes in microemulsions of AOT in nonpolar organic solvents for fabrication of enzyme electrodes.

    PubMed

    Shipovskov, Stepan; Trofimova, Daria; Saprykin, Eduard; Christenson, Andreas; Ruzgas, Tautgirdas; Levashov, Andrey V; Ferapontova, Elena E

    2005-11-01

    A new technique suitable for automated, large-scale fabrication of enzyme electrodes by air-spraying enzymes in organic inks is presented. Model oxidoreductases, tyrosinase (Tyr) and glucose oxidase (GOx), were adapted to octane-based ink by entrapment in a system of reverse micelles (RM) of surfactant AOT in octane to separate and stabilize the catalytically active forms of the enzymes in nonpolar organic media. Nonpolar caoutchouk polymer was also used to create a kind of "dry micelles" at the electrode/solution interface. Enzyme/RM/polymer-containing organic inks were air-brushed onto conductive supports and were subsequently covered by sprayed Nafion membranes. The air-brushed enzyme electrodes exhibited relevant bioelectrocatalytic activity toward catechol and glucose, with a linear detection range of 0.1-100 microM catechol and 0.5-7 mM glucose; the sensitivities were 2.41 A M(-1) cm(-2) and 2.98 mA M(-1) cm(-2) for Tyr and GOx electrodes, respectively. The proposed technique of air-brushing enzymes in organic inks enables automated construction of disposable enzyme electrodes of various designs on a mass-production scale. PMID:16255612

  9. Dielectric depolarisation and concerted collective dynamics in AOT reverse micelles with and without ubiquitin.

    PubMed

    Schmollngruber, Michael; Braun, Daniel; Oser, Daniel; Steinhauser, Othmar

    2016-02-01

    In this computational study we present molecular dynamics (MD) simulations of reverse micelles, i.e. nano-scale water pools encapsulated by sodium bis(2-ethylhexyl) sulfosuccinate (AOT) and dissolved in isooctane. Although consisting of highly polar components, such micro-emulsions exhibit surprisingly low dielectric permittivity, both static and frequency-dependent. This finding is well supported by experimental dielectric measurements. Furthermore, the computational dielectric spectra of reverse micelles with and without the polar protein ubiquitin are almost identical. A detailed component analysis of our simulated systems reveals the underlying mechanism of the observed dielectric depolarisation. While each component by itself would make a remarkable contribution to the static dielectric permittivity, mutual compensation leads to the observed marginal net result. This compensatory behavior is maintained for all but the highest frequencies. Dielectric model theory adapted to the peculiarities of reverse micelles provides an explanation: embedding a system in a cavity engulfed by a low dielectric medium automatically leads to depolarization. In this sense experiment, simulation and theory are in accordance. PMID:26751837

  10. Molecular dynamics simulations of AOT-water/formamide reverse micelles: Structural and dynamical properties

    NASA Astrophysics Data System (ADS)

    Pomata, Matías H. H.; Laria, Daniel; Skaf, Munir S.; Elola, M. Dolores

    2008-12-01

    We present results from molecular dynamics simulations performed on reverse micelles immersed in cyclohexane. Three different inner polar phases are considered: water (W), formamide (FM), and an equimolar mixture of the two solvents. In all cases, the surfactant was sodium bis(2-ethylhexyl) sulfosuccinate (usually known as AOT). The initial radii of the micelles were R~15 A˚, while the corresponding polar solvent-to-surfactant molar ratios were intermediate between w0=4.3 for FM and w0=7 for W. The resulting overall shapes of the micelles resemble distorted ellipsoids, with average eccentricities of the order of ~0.75. Moreover, the pattern of the surfactant layer separating the inner pool from the non-polar phase looks highly irregular, with a roughness characterized by length scales comparable to the micelle radii. Solvent dipole orientation polarization along radial directions exhibit steady growths as one moves from central positions toward head group locations. Local density correlations within the micelles indicate preferential solvation of sodium ionic species by water, in contrast to the behavior found in bulk equimolar mixtures. Still, a sizable fraction of ~90% of Na+ remains associated with the head groups. Compared to bulk results, the translational and rotational modes of the confined solvents exhibit important retardations, most notably those operated in rotational motions where the characteristic time scales may be up to 50 times larger. Modifications of the intramolecular connectivity expressed in terms of the average number of hydrogen bonds and their lifetimes are also discussed.

  11. Analysis of the amino acids of soy globulins by AOT reverse micelles and aqueous buffer.

    PubMed

    Zhao, Xiaoyan; Chen, Jun; Lu, Zhifang; Ling, Xiangqing; Deng, Peng; Zhu, Qingjun; Du, Fangling

    2011-10-01

    The 7S and 11S globulins from soybean proteins using reverse micelle and aqueous buffer extraction methods were characterized by using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and scanning electron microscope (SEM), and their amino acid compositions were also evaluated. SDS-PAGE did not show electrophoretic differences between 7S and 11S globulin subunits with two extraction methods. SEM analysis showed that the AOT reverse micelle processing of 7S and 11S globulins induced a reduction of droplet size. Some individual amino acid contents of 7S and 11S globulins using two extraction methods were different, some were similar. In all the samples, the glutamic acid, aspartic acid, and leucine were the dominant amino acids while the cystine and methionine were the first-limiting amino acids. The proportion of essential amino acids to the total amino acids (E/T) of the 7S globulin from aqueous buffer and reverse micelles was similar. While significant differences were obtained in the proportion of E/T of the 11S globulin. PMID:21647686

  12. New developments in the representation of Saharan dust sources in the aerosol-climate model ECHAM6-HAM2

    NASA Astrophysics Data System (ADS)

    Heinold, B.; Tegen, I.; Schepanski, K.; Banks, J. R.

    2015-09-01

    In the aerosol-climate model ECHAM6-HAM2, dust source activation (DSA) observations from Meteosat Second Generation (MSG) satellite are proposed to replace the original source area parameterization over the Sahara Desert. The new setup is tested in nudged simulations for the period 2007 to 2008. The evaluation is based on comparisons to dust emission events inferred from MSG dust index imagery, AERONET sun photometer observations, and satellite retrievals of aerosol optical thickness (AOT). The model results agree well with AERONET measurements. Good correlations between model results and MSG-SEVIRI dust AOT as well as Multi-angle Imaging Spectro-Radiometer (MISR) AOT indicate that also the spatial dust distribution is well reproduced. ECHAM6-HAM2 computes a more realistic geographical distribution and up to 20 % higher annual Saharan dust emissions, using the MSG-based source map. The representation of dust AOT is partly improved in the southern Sahara and Sahel. In addition, the spatial variability is increased towards a better agreement with observations depending on the season. Thus, using the MSG DSA map can help to circumvent the issue of uncertain soil input parameters. An important issue remains the need to improve the model representation of moist convection and stable nighttime conditions. Compared to sub-daily DSA information from MSG-SEVIRI and results from a regional model, ECHAM6-HAM2 notably underestimates the important fraction of morning dust events by the breakdown of the nocturnal low-level jet, while a major contribution is from afternoon-to-evening emissions.

  13. Temporal consistency of lidar observations during aerosol transport events in the framework of the ChArMEx/ADRIMED campaign at Minorca in June 2013

    NASA Astrophysics Data System (ADS)

    Chazette, Patrick; Totems, Julien; Ancellet, Gérard; Pelon, Jacques; Sicard, Michaël

    2016-03-01

    We performed synergetic daytime and nighttime active and passive remote-sensing observations at Minorca (Balearic Islands, Spain), over more than 3 weeks during the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Effect in the Mediterranean (ChArMEx/ADRIMED) special observation period (SOP 1a, June-July 2013). We characterized the aerosol optical properties and type in the low and middle troposphere using an automated procedure combining Rayleigh-Mie-Raman lidar (355, 387 and 407 nm) with depolarization (355 nm) and AERONET Cimel® sun-photometer data. Results show a high variability due to varying dynamical forcing. The mean column-averaged lidar backscatter-to-extinction ratio (BER) was close to 0.024 sr-1 (lidar ratio of ˜ 41.7 sr), with a large dispersion of ±33 % over the whole observation period due to changing atmospheric transport regimes and aerosol sources. The ground-based remote-sensing measurements, coupled with satellite observations, allowed the documentation of (i) dust particles up to 5 km (above sea level) in altitude originating from Morocco and Algeria from 15 to 18 June with a peak in aerosol optical thickness (AOT) of 0.25 ± 0.05 at 355 nm, (ii) a long-range transport of biomass burning aerosol (AOT = 0.18 ± 0.16) related to North American forest fires detected from 26 to 28 June 2013 by the lidar between 2 and 7 km and (iii) mixture of local sources including marine aerosol particles and pollution from Spain. During the biomass burning event, the high value of the particle depolarization ratio (8-14 %) may imply the presence of dust-like particles mixed with the biomass burning aerosols in the mid-troposphere. For the field campaign period, we also show linearity with SEVIRI retrievals of the aerosol optical thickness despite 35 % relative bias, which is discussed as a function of aerosol type.

  14. Temporal consistency of lidar observables during aerosol transport events in the framework of the ChArMEx/ADRIMED campaign at Menorca Island in June 2013

    NASA Astrophysics Data System (ADS)

    Chazette, P.; Totems, J.; Ancellet, G.; Pelon, J.; Sicard, M.

    2015-11-01

    We performed synergetic daytime and night-time active and passive remote sensing observations at Menorca (Balearic Island, Spain), over more than 3 weeks during the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Effect in the Mediterranean (ChArMEx/ADRIMED) special observation period (SOP 1a, June-July 2013). We characterized the aerosol optical properties and type in the low and middle troposphere using an automated procedure combining Rayleigh-Mie-Raman lidar (355, 387 and 407 nm) with depolarization (355 nm) and AERONET Cimel® sun-photometer data. Results show a high variability due to varying dynamical forcing. The mean column-averaged lidar backscatter-to-extinction ratio (BER) was close to 0.024 sr-1 (lidar ratio of ∼ 41.7 sr), with a large dispersion of ±33 % over the whole observation period due to changing atmospheric transport regimes and aerosol sources. The ground-based remote sensing measurements, coupled with satellite observations, allowed to document (i) dust particles up to 5 km a.s.l. in altitude originating from Morocco and Algeria from 15 to 18 June with a peak in aerosol optical thickness (AOT) of 0.25 ± 0.05 at 355 nm, (ii) a long-range transport of biomass burning aerosol (AOT = 0.18 ± 0.16) related to North American forest fires detected from 26 to 28 June 2013 by the lidar between 2 and 7 km and (iii) mixture of local sources including marine aerosol particles and pollution from Spain. During the biomass burning event, the high value of the particle depolarization ratio (8-14 %) may imply the presence of dust-like particles mixed with the biomass burning aerosols in the mid troposphere. We show also linearity with SEVIRI retrievals of the aerosol optical thickness within 35 % relative bias, which is discussed as a function of aerosol type.

  15. Oxytocin (OT) and arginine-vasopressin (AVP) act on OT receptors and not AVP V1a receptors to enhance social recognition in adult Syrian hamsters (Mesocricetus auratus).

    PubMed

    Song, Zhimin; Larkin, Tony E; Malley, Maureen O'; Albers, H Elliott

    2016-05-01

    Social recognition is a fundamental requirement for all forms of social relationships. A majority of studies investigating the neural mechanisms underlying social recognition in rodents have investigated relatively neutral social stimuli such as juveniles or ovariectomized females over short time intervals (e.g., 2h). The present study developed a new testing model to study social recognition among adult males using a potent social stimulus. Flank gland odors are used extensively in social communication in Syrian hamsters and convey important information such as dominance status. We found that the recognition of flank gland odors after a 3min exposure lasted for at least 24h, substantially longer than the recognition of other social cues in rats and mice. Intracerebroventricular injections of OT and AVP prolonged the recognition of flank gland odor for up to 48h. Selective OTR but not V1aR agonists, mimicked these enhancing effects of OT and AVP. Similarly, selective OTR but not V1aR antagonists blocked recognition of the odors after 20min. In contrast, the recognition of non-social stimuli was not blocked by either the OTR or the V1aR antagonists. Our findings suggest both OT and AVP enhance social recognition via acting on OTRs and not V1aRs and that the recognition enhancing effects of OT and AVP are limited to social stimuli. PMID:26975586

  16. OT2_smalhotr_3: Herschel Extreme Lensing Line Observations (HELLO)

    NASA Astrophysics Data System (ADS)

    Malhotra, S.

    2011-09-01

    We request 59.8 hours of Herschel time to observe 20 normal star-forming galaxies in the [CII] 158 micron and [OI] 63 micron lines. These galaxies lie at high redshift (1OT1, 49 high redshift IR luminous galaxies were approved for spectroscopy, but only two so-called normal galaxies were included. This is an imbalance that should be corrected, to balance Herschel's legacy.

  17. Silver nanoparticles in hydrogels and microemulsions—a comparative account of their properties and bio-activity

    NASA Astrophysics Data System (ADS)

    Ray, Debajyoti; Chatterjee, Saptarshi; Sarkar, Keka; De, Swati

    2014-09-01

    Stable silver nanoparticles were prepared in sodium Aerosol OT (AOT) based microemulsions and hydrogels. The various gel and microemulsion compositions used for nanoparticle synthesis were obtained from the phase diagram of the AOT/n-heptane/H2O system. It was found that only in gels can AOT play a dual role of stabilizer as well as reducing agent. In microemulsions, AOT acts as a stabilizer only. In gels, the commonly used NaBH4 reduction results in spherical silver nanoparticles while the AOT based reduction yields highly facetted particles. In microemulsion however, larger particles of undefined shapes are formed in low yield while for the gels, a large number of particles are formed. The synthesized silver nanoparticles show strong antibacterial activity.

  18. In situ X-ray polymerization: from swollen lamellae to polymer-surfactant complexes.

    PubMed

    Agzenai, Yahya; Lindman, Björn; Alfredsson, Viveka; Topgaard, Daniel; Renamayor, Carmen S; Pacios, Isabel E

    2014-01-30

    The influence of the monomer diallyldimethylammonium chloride (D) on the lamellar liquid crystal formed by the anionic surfactant aerosol OT (AOT) and water is investigated, determining the lamellar spacings by SAXS and the quadrupolar splittings by deuterium NMR, as a function of the D or AOT concentrations. The cationic monomer D induces a destabilization of the AOT lamellar structure such that, at a critical concentration higher than 5 wt %, macroscopic phase separation takes place. When the monomer, which is dissolved in the AOT lamellae, is polymerized in situ by X-ray initiation, a new collapsed lamellar phase appears, corresponding to the complexation of the surfactant with the resulting polymer. A theoretical model is employed to analyze the variation of the interactions between the AOT bilayers and the stability of the lamellar structure. PMID:24410395

  19. Quantification of model uncertainty in aerosol optical thickness retrieval from Ozone Monitoring Instrument (OMI) measurements

    NASA Astrophysics Data System (ADS)

    Määttä, A.; Laine, M.; Tamminen, J.; Veefkind, J. P.

    2013-09-01

    We study uncertainty quantification in remote sensing of aerosols in the atmosphere with top of the atmosphere reflectance measurements from the nadir-viewing Ozone Monitoring Instrument (OMI). Focus is on the uncertainty in aerosol model selection of pre-calculated aerosol models and on the statistical modelling of the model inadequacies. The aim is to apply statistical methodologies that improve the uncertainty estimates of the aerosol optical thickness (AOT) retrieval by propagating model selection and model error related uncertainties more realistically. We utilise Bayesian model selection and model averaging methods for the model selection problem and use Gaussian processes to model the smooth systematic discrepancies from the modelled to observed reflectance. The systematic model error is learned from an ensemble of operational retrievals. The operational OMI multi-wavelength aerosol retrieval algorithm OMAERO is used for cloud free, over land pixels of the OMI instrument with the additional Bayesian model selection and model discrepancy techniques. The method is demonstrated with four examples with different aerosol properties: weakly absorbing aerosols, forest fires over Greece and Russia, and Sahara dessert dust. The presented statistical methodology is general; it is not restricted to this particular satellite retrieval application.

  20. Uncertainty quantification in aerosol optical thickness retrieval from Ozone Monitoring Instrument (OMI) measurements

    NASA Astrophysics Data System (ADS)

    Määttä, A.; Laine, M.; Tamminen, J.; Veefkind, J. P.

    2013-10-01

    The space borne measurements provide global view of atmospheric aerosol distribution. The Ozone Monitoring Instrument (OMI) on board NASAs Earth Observing System (EOS) Aura satellite is a Dutch-Finnish nadir-viewing solar backscatter spectrometer measuring in the ultraviolet and visible wavelengths. OMI measures several trace gases and aerosols that are important in many air quality and climate studies. The OMI aerosol measurements are used, for example, for detecting volcanic ash plumes, wild fires and transportation of desert dust. We present a methodology for improving the uncertainty quantification in the aerosols retrieval algorithm. We have used the OMI measurements in this feasibility study. Our focus is on the uncertainties originating from the pre-calculated aerosol models. These models are never complete descriptions of the reality. This aerosol model uncertainty is estimated using Gaussian processes with computational tools from spatial statistics. Our approach is based on smooth systematic differences between the observed and modelled reflectances. When acknowledging this model inadequacy in the estimation of aerosol optical thickness (AOT), the uncertainty estimates are more realistic. We present here a real world example of applying the methodology.

  1. Tropospheric Aerosols

    NASA Astrophysics Data System (ADS)

    Buseck, P. R.; Schwartz, S. E.

    2003-12-01

    It is widely believed that "On a clear day you can see forever," as proclaimed in the 1965 Broadway musical of the same name. While an admittedly beautiful thought, we all know that this concept is only figurative. Aside from Earth's curvature and Rayleigh scattering by air molecules, aerosols - colloidal suspensions of solid or liquid particles in a gas - limit our vision. Even on the clearest day, there are billions of aerosol particles per cubic meter of air.Atmospheric aerosols are commonly referred to as smoke, dust, haze, and smog, terms that are loosely reflective of their origin and composition. Aerosol particles have arisen naturally for eons from sea spray, volcanic emissions, wind entrainment of mineral dust, wildfires, and gas-to-particle conversion of hydrocarbons from plants and dimethylsulfide from the oceans. However, over the industrial period, the natural background aerosol has been greatly augmented by anthropogenic contributions, i.e., those produced by human activities. One manifestation of this impact is reduced visibility (Figure 1). Thus, perhaps more than in other realms of geochemistry, when considering the composition of the troposphere one must consider the effects of these activities. The atmosphere has become a reservoir for vast quantities of anthropogenic emissions that exert important perturbations on it and on the planetary ecosystem in general. Consequently, much recent research focuses on the effects of human activities on the atmosphere and, through them, on the environment and Earth's climate. For these reasons consideration of the geochemistry of the atmosphere, and of atmospheric aerosols in particular, must include the effects of human activities. (201K)Figure 1. Impairment of visibility by aerosols. Photographs at Yosemite National Park, California, USA. (a) Low aerosol concentration (particulate matter of aerodynamic diameter less than 2.5 μm, PM2.5=0.3 μg m-3; particulate matter of aerodynamic diameter less than 10

  2. Retrieval of aerosol optical and micro-physical properties with 2D-MAX-DOAS

    NASA Astrophysics Data System (ADS)

    Ortega, Ivan; Coburn, Sean; Hostetler, Chris; Ferrare, Rich; Hair, Johnathan; Kassianov, Evgueni; Barnard, James; Berg, Larry; Schmid, Beat; Tomlinson, Jason; Hodges, Gary; Lantz, Kathy; Wagner, Thomas; Volkamer, Rainer

    2015-04-01

    Recent retrievals of 2 dimensional (2D) Multi-AXis Differential Optical Absorption Spectroscopy (2D-MAX-DOAS) have highlighted its importance in order to infer diurnal horizontal in-homogeneities around the measurement site. In this work, we expand the capabilities of 2D measurements in order to estimate simultaneously aerosol optical and micro-physical properties. Specifically, we present a retrieval method to obtain: (1) aerosol optical thickness (AOT) in the boundary layer (BL) and free troposphere (FT) and (2) the effective complex refractive index and the effective radius of the aerosol column size distribution. The retrieval method to obtain AOT is based on an iterative comparison of measured normalized radiances, oxygen collision pair (O4), and absolute Raman Scattering Probability (RSP) with the forward model calculations derived with the radiative transfer model McArtim based on defined aerosol extinction profiles. Once the aerosol load is determined we use multiple scattering phase functions and single scattering albedo (SSA) obtained with Mie calculations which then constrain the RTM to forward model solar almucantar normalized radiances. The simulated almucantar normalized radiances are then compared to the measured normalized radiances. The best-fit, determined by minimizing the root mean square, retrieves the complex refractive index, and effective radius. We apply the retrieval approach described above to measurements carried out during the 2012 intensive operation period of the Two Column Aerosol Project (TCAP) held on Cape Cod, MA, USA. Results are presented for two ideal case studies with both large and small aerosol loading and similar air mass outflow from the northeast coast of the US over the West Atlantic Ocean. The aerosol optical properties are compared with several independent instruments, including the NASA Langley airborne High Spectral Resolution Lidar (HSRL-2) for highly resolved extinction profiles during the overpasses, and with the

  3. OmniTread OT-4 serpentine robot: new features and experiments

    NASA Astrophysics Data System (ADS)

    Borenstein, Johann; Hansen, Malik

    2007-04-01

    Serpentine robots are slender, multi-segmented vehicles designed to provide greater mobility than conventional wheeled or tracked robots. Serpentine robots are thus ideally suited for urban search and rescue, military intelligence gathering, and for surveillance and inspection tasks in hazardous and hard-to-reach environments. One such serpentine robot, developed at the University of Michigan, is the "OmniTread OT-4." The OT-4 comprises seven segments, which are linked to each other by 2-degree-of-freedom joints. The OT-4 can climb over obstacles that are much higher than the robot itself, propel itself inside pipes of different diameters, and traverse even the most difficult terrain, such as rocks or the rubble of a collapsed structure. The foremost and unique design characteristic of the OT-4 is the use of pneumatic bellows to actuate the joints. These bellows allow simultaneous control of position and stiffness for each joint. Controllable stiffness is of crucial importance in serpentine robots, which require stiff joints to cross gaps and compliant joints to conform to rough terrain for effective propulsion. Another unique feature of the OmniTread design is the maximal coverage of all four sides with driven tracks. This design makes the robot indifferent to roll-overs, which are happen frequently when the slender bodies of serpentine robots travel over rugged terrain. This paper describes the OmniTread concept as well as its latest technical features, and an extensive Experiment Results Section documents the abilities of the OT-4.

  4. Droplet polydispersity and shape fluctuations in AOT [bis(2-ethylhexyl)sulfosuccinate sodium salt] microemulsions studied by contrast variation small-angle neutron scattering

    NASA Astrophysics Data System (ADS)

    Arleth, Lise; Pedersen, Jan Skov

    2001-06-01

    Microemulsions consisting of AOT water, and decane or iso-octane are studied in the region of the phase diagram where surfactant covered water droplets are formed. The polydispersity and shape fluctuations of the microemulsion droplets are determined and compared in the two different alkane types. Conductivity measurements show that there is a pronounced dependence of the temperature behavior of the microemulsion on the type of alkane used. In both cases the microemulsion droplets start to form larger aggregates when the temperature increases. But in the system with decane this aggregation temperature occurs at a temperature about 10 °C lower than in a similar system with iso-octane. Aggregation phenomena are avoided and the two systems are at approximately the same reduced temperature with respect to the aggregation temperature when the temperature of the AOT/D2O/decane microemulsion is 10 °C and the temperature of the AOT/D2O/iso-octane microemulsion is 20 °C. Contrast variation small-angle neutron scattering measurements are performed at these temperatures on systems with volume fractions of 5% D2O+AOT by varying the scattering length density of the alkane. The small-angle scattering for 11 different contrasts evenly distributed around the match points are studied for each sample. The scattering data for the different contrasts are analyzed using a molecular constrained model for ellipsoidal droplets of water covered by AOT, interacting as polydisperse hard spheres. All contrasts are fitted simultaneously by taking the different contrast factors into account. The analysis show that at the same reduced temperature with respect to the aggregation temperature the droplet size, polydispersity index, the size of the shape fluctuations are similar in the two systems. A polydispersity index (σ/R of the Gaussian size distribution) of 16% and an average axis ratio of the droplets of 1.56 is found in the AOT/D2O/decane microemulsion. In the AOT/D2O/iso-octane system

  5. Degradation of carbofuran derivatives in restricted water environments: basic hydrolysis in AOT-based microemulsions.

    PubMed

    Morales, Jorge; Manso, José A; Cid, Antonio; Lodeiro, Carlos; Mejuto, Juan Carlos

    2012-04-15

    The effect of sodium bis(2-ethylhexyl)sulfosuccinate/isooctane/water microemulsions on the stability of 2,2-dimethyl-2,3-dihydro-1-benzofuran-7-yl methylcarbamate (carbofuran, CF), 3-hydroxy-2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate (3-hydroxycarbofuran, HCF) and 3-keto-2,3-dihydro-2,2-dimethylbenzofuran-7-yl methylcarbamate (3-ketocarbofuran, KCF) in basic media has been studied. The presence of these microheterogeneous media implies a large basic hydrolysis of CF and HCF on increasing surfactant concentration and, also, on increasing water content in the microemulsion. The hydrolysis rate constants are approximately 2- and 10-fold higher than those in pure water for HCF and CF, respectively. In contrast, a steep descent in the rate of decomposition for KCF was observed. These behaviours can be ascribed to the presence of CF derivatives both in the hydrophilic phase and in the lipophilic phase, while the hydroxyl ions are only restricted to the water pool of the microemulsion (hydrophilic phase). The kinetic rate constants for the basic hydrolysis in AOT-based microemulsions have been obtained on the basis of a pseudophase model. Taking into account that an important part of soils are colloids, the possibility of the presence of restricted water environments implies that soil composition and its structure will play an important role in the stability of these carbamates. In fact, we observed that the presence of these restricted aqueous media in the environment, in particular in watersheds and in wastewaters, could reduce significantly the half-life of these pesticides (33% and 91% for HCF and CF, respectively). PMID:22325067

  6. Effect of AOT on enzymatic activity of the organic solvent resistant tyrosinase from Streptomyces sp. REN-21 in aqueous solutions and water-in-oil microemulsions.

    PubMed

    Rodakiewicz-Nowak, Janina; Ito, Masaaki

    2005-04-15

    The effect of AOT (sodium-bis(2-ethylhexyl sulfosuccinate)) on enzymatic activity of the organic solvent resistant tyrosinase (OSRT) in aqueous phosphate buffer solutions and in water-in-oil microemulsions of the water/AOT/isooctane system has been investigated. In contrast to mushroom tyrosinase, AOT does not activate OSRT in aqueous solutions, altering its activity very little at concentrations lower than 2 mM. Increasing contents of AOT in isooctane reduce the observed initial reaction rates of oxidation of t-butylcatechol (tBC) and 4-methylcatechol (4-MC). Similarly to mushroom tyrosinase, the effect has been described using an equation based on preferential binding of the substrates by surfactant interface layers. The apparent Michaelis-Menten substrate binding constants increase linearly with AOT concentration (with slopes of 0.12+/-0.02 and 0.051+/-0.006 for tBC and 4-MC, respectively), and the effective enzyme turnover number in the microemulsions remains practically constant. PMID:15780309

  7. The Time Series Technique for Aerosol Retrievals over Land from MODIS: Algorithm MAIAC

    NASA Technical Reports Server (NTRS)

    Lyapustin, Alexei; Wang, Yujie

    2008-01-01

    Atmospheric aerosols interact with sun light by scattering and absorbing radiation. By changing irradiance of the Earth surface, modifying cloud fractional cover and microphysical properties and a number of other mechanisms, they affect the energy balance, hydrological cycle, and planetary climate [IPCC, 2007]. In many world regions there is a growing impact of aerosols on air quality and human health. The Earth Observing System [NASA, 1999] initiated high quality global Earth observations and operational aerosol retrievals over land. With the wide swath (2300 km) of MODIS instrument, the MODIS Dark Target algorithm [Kaufman et al., 1997; Remer et al., 2005; Levy et al., 2007] currently complemented with the Deep Blue method [Hsu et al., 2004] provides daily global view of planetary atmospheric aerosol. The MISR algorithm [Martonchik et al., 1998; Diner et al., 2005] makes high quality aerosol retrievals in 300 km swaths covering the globe in 8 days. With MODIS aerosol program being very successful, there are still several unresolved issues in the retrieval algorithms. The current processing is pixel-based and relies on a single-orbit data. Such an approach produces a single measurement for every pixel characterized by two main unknowns, aerosol optical thickness (AOT) and surface reflectance (SR). This lack of information constitutes a fundamental problem of the remote sensing which cannot be resolved without a priori information. For example, MODIS Dark Target algorithm makes spectral assumptions about surface reflectance, whereas the Deep Blue method uses ancillary global database of surface reflectance composed from minimal monthly measurements with Rayleigh correction. Both algorithms use Lambertian surface model. The surface-related assumptions in the aerosol retrievals may affect subsequent atmospheric correction in unintended way. For example, the Dark Target algorithm uses an empirical relationship to predict SR in the Blue (B3) and Red (B1) bands from the

  8. Catalytic activity of lignin peroxidase and partition of veratryl alcohol in AOT/isooctane/toluene/water reverse micelles.

    PubMed

    Zhang, Wenjuan; Huang, Xirong; Li, Yuezhong; Qu, Yinbo; Gao, Peiji

    2006-04-01

    The activity of lignin peroxidase (LiP) and the partition of its optimum substrate veratryl alcohol (VA) in sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/isooctane/toluene/water reverse micelles were studied in this paper to understand the microheterogeneous effect of the medium on the catalytic properties of LiP hosted in the reverse micelle. Results showed that LiP from Phanerochaete chrysosporium could express its activity in the reverse micelles, but its activity depended, to a great extent, on the composition of the reverse micelles. Optimum activity occurred at a molar ratio of water to AOT (omega0) of 11, a pH value of 3.6, and a volume ratio of isooctane to toluene of 7-9. Under optimum conditions, the half-life of LiP was circa 12 h. The dependence of LiP activity on the volume fraction of water in the medium (theta), at a constant omega0 value of 11, indicated that VA was mainly solubilized in the pseudophase of the reverse micelle. Based on the pseudobiphasic model and the corresponding kinetic method, a linear line can be obtained in a plot of apparent Michaelis constant of VA vs theta, and the partition coefficient of VA between the pseudophase and the organic solvent phase was determined to be 35.8, which was higher than that (22.3) between bulk water and the corresponding mixed organic solvent. H2O2 inhibited LiP at concentrations higher than 80 microM; this concentration value seems to be different from that in aqueous solution (about 3 mM). The differences mentioned above should be ascribed to the microheterogeneity and the interface of the AOT reverse micelle. PMID:16080008

  9. Expression and Developmental Regulation of Oxytocin (OT) and Oxytocin Receptors (OTR) in the Enteric Nervous System (ENS) and Intestinal Epithelium

    PubMed Central

    Welch, Martha G.; Tamir, Hadassah; Gross, Kara J.; Chen, Jason; Anwar, Muhammad; Gershon, Michael D.

    2011-01-01

    Although oxytocin (OT) and oxytocin receptor (OTR) are known for roles in parturition and milk let-down, they are not hypothalamus-restricted. OT is important in nurturing and opposition to stress. Transcripts encoding OT and OTR have been reported in adult human gut, and OT affects intestinal motility. We tested the hypotheses that OT is endogenous to the enteric nervous system (ENS) and that OTR signaling may participate in enteric neurophysiology. Reverse transcriptase polymerase chain reaction confirmed OT and OTR transcripts in adult mouse and rat gut and in precursors of enteric neurons immunoselected from fetal rats. Enteric OT and OTR expression continued through adulthood but was developmentally regulated, peaking at postnatal day 7. Coincidence of the immunoreactivities of OTR and the neural marker Hu was 100% in the P3 and 71% in the adult myenteric plexus, when submucosal neurons were also OTR-immunoreactive. Co-localization with NeuN established that intrinsic primary afferent neurons are OTR-expressing. Because OTR transcripts and protein were detected in the nodose ganglia, OT signaling might also affect extrinsic primary afferent neurons. Although OT immunoreactivity was found only in ~1% of myenteric neurons, extensive OT-immunoreactive varicosities surrounded many others. Villus enterocytes were OTR-immunoreactive through postnatal day 17; however, by postnatal day 19, immunoreactivity waned to become restricted to crypts and concentrated at crypt-villus junctions. Immunoelectron microscopy revealed plasmalemmal OTR at enterocyte adherens junctions. We suggest that OT and OTR signaling might be important in ENS development and function and might play roles in visceral sensory perception and neural modulation of epithelial biology. PMID:19003903

  10. Photophysics of 4- N, N-dimethylamino cinnamaldehyde in AOT reverse micelles and exploration of its position and orientation

    NASA Astrophysics Data System (ADS)

    Panja, Subhasis; Chakravorti, Sankar

    2003-01-01

    An attempt has been made in this Letter to locate the position and orientation of 4- N, N-dimethylamino cinnamaldehyde (DMACA) inside sodium bis(2-ethylhexyl) sulfosuccinate (AOT)- n-heptane reverse micelle based on change in photophysical properties of DMACA compared to that in n-heptane. It has been proposed that the possibility of finding the donor moiety inside the small water pool of reverse micelle is maximum while the acceptor group straddles in the remaining part of the reverse micelle. The micropolarity in the vicinity of the donor moiety has been computed in terms of dielectric constant with varying water pool size.

  11. Changes in atmospheric aerosol loading retrieved from space based measurements during the past decade

    NASA Astrophysics Data System (ADS)

    Yoon, J.; Burrows, J. P.; Vountas, M.; von Hoyningen-Huene, W.; Chang, D. Y.; Richter, A.; Hilboll, A.

    2013-10-01

    Atmospheric aerosol, generated from natural and anthropogenic sources, plays a key role in regulating visibility, air quality, and acid deposition. It is directly linked to and impacts on human health. It also reflects and absorbs incoming solar radiation and thereby influences the climate change. The cooling by aerosols is now recognized to have partly masked the atmospheric warming from fossil fuel combustion emissions. The role and potential management of short-lived climate pollutants such as aerosol are currently a topic of much scientific and public debate. Our limited knowledge of atmospheric aerosol and its influence on the Earth's radiation balance has a significant impact on the accuracy and error of current predictions of the future global climate change. In the past decades, environmental legislation in industrialized countries has begun to limit the release of anthropogenic pollutants. In contrast, in Asia as a result of the recent rapid economic development, emissions from industry and traffic have increased dramatically. In this study, the temporal changes/trends of atmospheric aerosols, derived from the satellite instruments MODIS (on board Terra and Aqua), MISR (Terra), and SeaWiFS (OrbView-2) during the past decade, are investigated. Whilst the aerosol optical thickness, AOT, over Western Europe decreases (i.e. by up to about -40% from 2003 to 2008) and parts of North America, a statistically significant increase (about +34% in the same period) over East China is observed and attributed to both the increase in industrial output and the Asian desert dust.

  12. Aerosol Data Assimilation with the Next Generation Meteorological Satellite (Himawari-8)

    NASA Astrophysics Data System (ADS)

    Yumimoto, K.; Sekiyama, T. T.; Murakami, H.; Kikuchi, M.; Nagao, T. M.; Tanaka, T. Y.; Ogi, A.; Maki, T.

    2015-12-01

    The Japan Meteorological Agency (JMA) launched a new generation geostationary meteorological satellite, Himawari-8, on 7 October 2014. The Advanced Himawari Imager (AHI) aboard Himawari-8 is a 16 channel multispectral imager including three observational bands (i.e. RGB) in visible lights with 1km horizontal and 10-minite temporal resolutions covering the East Asia and Western Pacific regions. The visible imaging sensor allows us to obtain aerosol optical observations with unprecedented spatial and temporal resolutions and horizontal coverage. Meteorological Research Institute (MRI)/JMA have been developing an aerosol data assimilation system with a global aerosol transport model (MASINGAR mk-2) and the Local Ensemble Transform Kalman Filter (LETKF) for the operational aerosol (Asian dust) forecasting system (Yumimoto et al., under review). In this study, we have the first attempt to assimilate aerosol retrievals derived from the next generation meteorological satellite in the assimilation system. Our preliminary experiment results show that assimilation of full disk aerosol optical thickness (AOT) from Himawari-8 successfully reduces overestimates of anthropogenic pollution outflow from the Asian Continent, and compensates underestimates of dust outflow from the Australian continent.

  13. A global outer-rise/outer-trench-slope (OR/OTS) earthquake study

    NASA Astrophysics Data System (ADS)

    Wartman, J. M.; Kita, S.; Kirby, S. H.; Choy, G. L.

    2009-12-01

    Using improved seismic, bathymetric, satellite gravity and other geophysical data, we investigated the seismicity patterns and focal mechanisms of earthquakes in oceanic lithosphere off the trenches of the world that are large enough to be well recorded at teleseismic distances. A number of prominent trends are apparent, some of which have been previously recognized based on more limited data [1], and some of which are largely new [2-5]: (1) The largest events and the highest seismicity rates tend to occur where Mesozoic incoming plates are subducting at high rates (e.g., those in the western Pacific and the Banda segment of Indonesia). The largest events are predominantly shallow normal faulting (SNF) earthquakes. Less common are reverse-faulting (RF) events that tend to be deeper and to be present along with SNF events where nearby seamounts, seamount chains and other volcanic features are subducting [Seno and Yamanaka, 1996]. Blooms of SNF OR/OTS events usually occur just after and seaward of great interplate thrust (IPT) earthquakes but are far less common after smaller IPT events. (2) Plates subducting at slow rates (<20 mm/a) often show sparse OR/OTS seismicity. It is unclear if such low activity is a long-term feature of these systems or is a consequence of the long return times of great IPT earthquakes (e.g., the sparse OR/OTS seismicity before the 26 December 2004 M9.2 Sumatra earthquake and many subsequent OR/OTS events). (3) OR/OTS shocks are generally sparse or absent where incoming plates are very young (<20 Ma) (e.g., Cascadia, southern Mexico, Nankai, and South Shetlands). (4) Subducting plates of intermediate age (20 to about 65 Ma) display a diversity of focal mechanisms and seismicity patterns. In the Philippines, NE Indonesia, and Melanesia, bands of reverse faulting events occur at or near the trench and SNF earthquakes are restricted to OR/OTS sites further from the trench. (5) Clustering of OR/OTS events of all types commonly occurs where

  14. MASTER OT J122114.34+472950.7 is a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Silverman, J. M.; Tucker, B. E.; Vinko, J.; Quimby, R.; Wheeler, J. C.; Chatzopoulos, E.

    2013-04-01

    We write that a spectrogram, obtained on Mar. 31.18 UT with the 9.2-m Hobby-Eberly Telescope (+ Marcario Low-Resolution Spectrograph) by J. Caldwell, shows that MASTER OT J122114.34+472950.7 is a type-Ia supernova. Correlation with a library of supernova spectra using the "SuperNova IDentification" code (SNID; Blondin and Tonry 2007, Ap.J. 666, 1024) indicates that MASTER OT J122114.34+472950.7 is SN 1999aa-like type-Ia supernova (Strolger, et al., 2002, A.J., 124, 2905; Garavini, et al., 2004, A.J., 128, 387) at maximum brightness.

  15. Atmospheric Aerosols

    NASA Technical Reports Server (NTRS)

    Pueschel, R. F.; Lawless, James G. (Technical Monitor)

    1994-01-01

    Aerosols, defined as particles and droplets suspended in air, are always present in the atmosphere. They are part of the earth-atmosphere climate system, because they interact with both incoming solar and outgoing terrestrial radiation. They do this directly through scattering and absorption, and indirectly through effects on clouds. Submicrometer aerosols usually predominate in terms of number of particles per unit volume of air. They have dimensions close to the wavelengths of visible light, and thus scatter radiation from the sun very effectively. They are produced in the atmosphere by chemical reactions of sulfur-, nitrogen- and carbon-containing gases of both natural and anthropogenic origins. Light absorption is dominated by particles containing elemental carbon (soot), produced by incomplete combustion of fossil fuels and by biomass burning. Light-scattering dominates globally, although absorption can be significant at high latitudes, particularly over highly reflective snow- or ice-covered surfaces. Other aerosol substances that may be locally important are those from volcanic eruptions, wildfires and windblown dust.

  16. Atmospheric aerosols size distribution properties in winter and pre-monsoon over western Indian Thar Desert location

    NASA Astrophysics Data System (ADS)

    Panwar, Chhagan; Vyas, B. M.

    2016-05-01

    The first ever experimental results over Indian Thar Desert region concerning to height integrated aerosols size distribution function in particles size ranging between 0.09 to 2 µm such as, aerosols columnar size distribution (CSD), effective radius (Reff), integrated content of total aerosols (Nt), columnar content of accumulation and coarse size aerosols particles concentration (Na) (size < 0.5 µm) and (Nc) (size between 0.5 to 2 µm) have been described specifically during winter (a stable weather condition and intense anthropogenic pollution activity period) and pre-monsoon (intense dust storms of natural mineral aerosols as well as unstable atmospheric weather condition period) at Jaisalmer (26.90°N, 69.90°E, 220 m above surface level (asl)) located in central Thar desert vicinity of western Indian site. The CSD and various derived other aerosols size parameters are retrieved from their average spectral characteristics of Aerosol Optical Thickness (AOT) from UV to Infrared wavelength spectrum measured from Multi-Wavelength solar Radiometer (MWR). The natures of CSD are, in general, bio-modal character, instead of uniformly distributed character and power law distributions. The observed primary peaks in CSD plots are seen around about 1013 m2 μm-1 at radius range 0.09-0.20 µm during both the seasons. But, in winter months, secondary peaks of relatively lower CSD values of 1010 to 1011 m2/μm-1 occur within a lower radius size range 0.4 to 0.6 µm. In contrast to this, while in dust dominated and hot season, the dominated secondary maxima of the higher CSD of about 1012 m2μm-3 is found of bigger aerosols size particles in a rage of 0.6 to 1.0 µm which is clearly demonstrating the characteristics of higher aerosols laden of bigger size aerosols in summer months relative to their prevailed lower aerosols loading of smaller size aerosols particles (0.4 to 0.6 µm) in cold months. Several other interesting features of changing nature of monthly spectral AOT

  17. Long non-coding RNA SOX2OT: expression signature, splicing patterns, and emerging roles in pluripotency and tumorigenesis

    PubMed Central

    Shahryari, Alireza; Jazi, Marie Saghaeian; Samaei, Nader M.; Mowla, Seyed J.

    2015-01-01

    SOX2 overlapping transcript (SOX2OT) is a long non-coding RNA which harbors one of the major regulators of pluripotency, SOX2 gene, in its intronic region. SOX2OT gene is mapped to human chromosome 3q26.3 (Chr3q26.3) locus and is extended in a high conserved region of over 700 kb. Little is known about the exact role of SOX2OT; however, recent studies have demonstrated a positive role for it in transcription regulation of SOX2 gene. Similar to SOX2, SOX2OT is highly expressed in embryonic stem cells and down-regulated upon the induction of differentiation. SOX2OT is dynamically regulated during the embryogenesis of vertebrates, and delimited to the brain in adult mice and human. Recently, the disregulation of SOX2OT expression and its concomitant expression with SOX2 have become highlighted in some somatic cancers including esophageal squamous cell carcinoma, lung squamous cell carcinoma, and breast cancer. Interestingly, SOX2OT is differentially spliced into multiple mRNA-like transcripts in stem and cancer cells. In this review, we are describing the structural and functional features of SOX2OT, with an emphasis on its expression signature, its splicing patterns and its critical function in the regulation of SOX2 expression during development and tumorigenesis. PMID:26136768

  18. 12 CFR 563b.515 - What information must I provide to OTS before I repurchase my shares?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 6 2013-01-01 2012-01-01 true What information must I provide to OTS before I... THE TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Post-Conversion § 563b.515 What information must I provide to OTS before I repurchase my shares? (a) To repurchase stock in...

  19. 12 CFR 563b.515 - What information must I provide to OTS before I repurchase my shares?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 12 Banks and Banking 6 2012-01-01 2012-01-01 false What information must I provide to OTS before I... THE TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Post-Conversion § 563b.515 What information must I provide to OTS before I repurchase my shares? (a) To repurchase stock in...

  20. 12 CFR 563b.515 - What information must I provide to OTS before I repurchase my shares?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false What information must I provide to OTS before I... THE TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Post-Conversion § 563b.515 What information must I provide to OTS before I repurchase my shares? (a) To repurchase stock in...

  1. 12 CFR 563b.515 - What information must I provide to OTS before I repurchase my shares?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 6 2014-01-01 2012-01-01 true What information must I provide to OTS before I... THE TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Post-Conversion § 563b.515 What information must I provide to OTS before I repurchase my shares? (a) To repurchase stock in...

  2. 12 CFR 563b.515 - What information must I provide to OTS before I repurchase my shares?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false What information must I provide to OTS before I... THE TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Post-Conversion § 563b.515 What information must I provide to OTS before I repurchase my shares? (a) To repurchase stock in...

  3. 12 CFR 516.220 - If OTS requests additional information to complete my application, how will it process my...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... complete my application, how will it process my application? 516.220 Section 516.220 Banks and Banking... Standard Treatment § 516.220 If OTS requests additional information to complete my application, how will it... your response. OTS will notify you that it has extended the period before the end of the initial...

  4. 12 CFR 516.220 - If OTS requests additional information to complete my application, how will it process my...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... complete my application, how will it process my application? 516.220 Section 516.220 Banks and Banking... Standard Treatment § 516.220 If OTS requests additional information to complete my application, how will it... your response. OTS will notify you that it has extended the period before the end of the initial...

  5. Dust transport over the eastern Mediterranean derived from Total Ozone Mapping Spectrometer, Aerosol Robotic Network, and surface measurements

    NASA Astrophysics Data System (ADS)

    Kalivitis, N.; Gerasopoulos, E.; Vrekoussis, M.; Kouvarakis, G.; Kubilay, N.; Hatzianastassiou, N.; Vardavas, I.; Mihalopoulos, N.

    2007-02-01

    Multiyear surface PM10 measurements performed on Crete Island, Greece, have been used in conjunction with satellite (Total Ozone Mapping Spectrometer (TOMS)) and ground-based remote sensing measurements (Aerosol Robotic Network (AERONET)) to enhance our understanding of the evolution of mineral dust events over the eastern Mediterranean. An analysis of southerly air masses at altitudes of 1000 and 3000 m over a 5 year period (2000-2005), showed that dust can potentially arrive over Crete, either simultaneously in the lower free troposphere and inside the boundary layer (vertical extended transport (VET)) or initially into the free troposphere with the heavier particles gradually being scavenged inside the boundary layer (free troposphere transport (FTT)). Both pathways present significant seasonal variations but on an annual basis contribute almost equally to the dust transport in the area. During VET the aerosol index (AI) derived from TOMS was significantly correlated with surface PM10, and in general AI was found to be adequate for the characterization of dust loadings over the eastern Mediterranean on a climatological basis. A significant covariance between PM10 and AOT was observed during VET as well, indicating that AOT levels from AERONET may be estimated by PM10 levels at the surface. Surface measurements are thus crucial for the validation of remote sensing measurements and hence are a powerful tool for the investigation of the impact of aerosols on climate.

  6. Cy3 in AOT reverse micelles I. Dimer formation revealed through steady-state and time-resolved spectroscopy.

    PubMed

    McPhee, Jeffrey T; Scott, Eric; Levinger, Nancy E; Van Orden, Alan

    2011-08-11

    Cyanine-3 (Cy3) fluorescent dye molecules confined in sodium di-2-ethylhexyl sulfosuccinate (AOT) reverse micelles were examined using steady-state absorption and emission as well as time-resolved fluorescence spectroscopy to understand the effect of confinement on the spectroscopic properties of the dye. This study explored a wide range of reverse micelle sizes, with hydrodynamic radii ranging from ∼1.7 to ∼5 nm. The relative concentrations of Cy3 and AOT reverse micelles were such that, on average, one dye molecule was present for every 2 × 10(4) to 9 × 10(5) reverse micelles. In the smallest reverse micelles examined, observed changes in the absorption and emission spectra and fluorescence lifetime of the dye molecules indicated H-aggregation of Cy3 into side-by-side dimers. It is hypothesized that this dimerization is governed by the high local concentrations that result from the confinement of the Cy3 in the reverse micelles. What is notable about this study is that this dimer occurs even at overall dye concentrations in the nanomolar range. Such concentrations are too low for aggregation to occur in bulk solution. Hence, the reverse micelles serve as nanocatalysts for this aggregation process. PMID:21761942

  7. Monitoring Aerosol Optical Properties in the ABL, Using Lidar System and Sunphotometer in Buenos Aires, Argentina

    NASA Astrophysics Data System (ADS)

    Pallotta, J.; Pawelko, E.; Otero, L.; Ristori, P.; D'Elia, R.; Gonzalez, F.; Dworniczak, J.; Vilar, O.; Quel, E.

    2009-03-01

    At the Lasers and Applications Research Center (CEILAP, CITEFA-CONICET, (34°33' S, 58°30' W), located in an industrial suburb of the metropolitan area (Villa Martelli, Buenos Aires, Argentina), operates a multiwavelength lidar, based on a Nd:Yag laser (Continuum Surelite III P-IV). This system emits in 1064, 532 and 355 nm simultaneously (10 Hz, 600 mJ @ 1064 nm) and allows the monitoring of the optical aerosols properties in the atmospheric boundary layer (ABL). On the same experimental site, an AERONET sunphotometer provides the AOT value. An analysis of boundary layer behaviour in some relevant days of March, from the years 2004 to 2006 is presented. On the days analyzed, no aerosols events and clouds were registered over the ABL. Evolutions of some characteristics of the ABL are presented, such as the height of the boundary layer, height of entrainment zone (EZ) and the entrainment flux ratio.

  8. 75 FR 76524 - Closed Meeting of the OTS Mutual Savings Association Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-08

    ... Office of Thrift Supervision Closed Meeting of the OTS Mutual Savings Association Advisory Committee AGENCY: Office of Thrift Supervision, Department of the Treasury. ACTION: Notice of Closed Meeting... held at the Office of Thrift Supervision, 1700 G Street, NW., Washington, DC 20552. The public...

  9. 75 FR 38188 - Closed Meeting of the OTS Mutual Savings Association Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-01

    ... Office of Thrift Supervision Closed Meeting of the OTS Mutual Savings Association Advisory Committee AGENCY: Department of the Treasury, Office of Thrift Supervision. ACTION: Notice of Closed Meeting... meeting will be held at the Office of Thrift Supervision, 1700 G Street, NW., Washington, DC 20552....

  10. 76 FR 7630 - Open Meeting of the OTS Minority Depository Institutions Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-10

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE TREASURY Office of Thrift Supervision Open Meeting of the OTS Minority Depository Institutions Advisory Committee AGENCY: Department of the Treasury, Office of Thrift Supervision. ACTION: Notice of meeting. SUMMARY:...

  11. 75 FR 13344 - Open Meeting of the OTS Minority Depository Institutions Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-19

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE TREASURY Office of Thrift Supervision Open Meeting of the OTS Minority Depository Institutions Advisory Committee AGENCY: Department of the Treasury, Office of Thrift Supervision. ACTION: Notice of meeting. SUMMARY:...

  12. 75 FR 63895 - Open Meeting of the OTS Minority Depository Institutions Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-18

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF THE TREASURY Office of Thrift Supervision Open Meeting of the OTS Minority Depository Institutions Advisory Committee AGENCY: Department of the Treasury, Office of Thrift Supervision. ACTION: Notice of meeting. SUMMARY:...

  13. MASTER OT J095503.19-355149.4 detection during FERMI Trigg 478121069 inspection

    NASA Astrophysics Data System (ADS)

    Lipunov, V.; Tiurina, N.; Gorbovskoy, E.; Buckley, D.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Gress, O.; Vlasenko, D.; Vladimirov, V.; Shumkov, V.; Shurpakov, S.; Kuvshinov, D.; Potter, S.; Kotze, M.

    2016-02-01

    MASTER-SAAO auto-detection system( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 09h 55m 03.19s -35d 51m 49.4s on 2016-02-25.89505 UT during Fermi trigger 478121069 inspection (Buckley et al., GCN #19092).

  14. OGLE-IV Pre-discovery Observations of MASTER OT J051032.58-692130.4

    NASA Astrophysics Data System (ADS)

    Mroz, P.; Udalski, A.; Wyrzykowski, L.; Pawlak, M.

    2016-05-01

    Gorbovskoy et al. (ATel #9039) reported the discovery of a bright optical transient MASTER OT J051032.58-692130.4 toward the Large Magellanic Cloud. The object is located in the field LMC509 that is regularly monitored by the OGLE-IV Survey.

  15. Swift observation of the LMC nova candidate MASTER OT J051032.58-692130.4

    NASA Astrophysics Data System (ADS)

    Sokolovsky, Kirill

    2016-05-01

    The optical transient MASTER & nbsp;OT & nbsp;J051032.58-692130.4 was discovered by MASTER-SAAO on 2016-05-10.72797 (ATel #9039). Pre-discovery images by OGLE-IV indicate that the outburst occurred some time between 2016-04-21.00403 and 28.97626 (ATel #9040).

  16. MASTER: young PSN(Ia) in bright PGC054958 and OTs

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Shurpakov, S.; Lipunov, V.; Lopez, R. Rebolo; Buckley, D.; Ricart, Serra; Israelyan, G.; Potter, S.; Kniazev, A.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Vlasenko, D.; Gorbunov, I.; Kuvshinov, D.; Vladimirov, V.; Popova, E.

    2016-04-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171 ) discovered OT source at (RA, Dec) = 15h 23m 33.04s +09d 21m 25.6s on 2016-04-04.09646 UT. PSN unfiltered magnitude is 17.7m (limit 19.5m).

  17. Pre-discovery observations of MASTER OT J004514.13+420007.2

    NASA Astrophysics Data System (ADS)

    Maehara, Hiroyuki

    2016-01-01

    I report pre-discovery observations of the possible nova in M31 MASTER OT J004514.13+420007.2 (ATel # 8603). The observations were performed with the 1.05-m Schmidt telescope and KWFC (Sako et al. 2012, SPIE, 8446, 84466L) at Kiso Observatory.

  18. Spectroscopic Classification of MASTER OT J110707.62-052244.0 as a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Zheng, W.; Kim, M.; Shivvers, I.; Yuk, H.; Filippenko, A. V.

    2015-11-01

    We report that inspection of a CCD spectrum (range 350-1050 nm) of MASTER OT J110707.62-052244.0 (ATel #8236), obtained on Nov. 11.57 UT with the Shane 3-m reflector (+ Kast spectrograph) at Lick Observatory, shows that the object is a normal Type Ia supernova roughly 1 week past maximum brightness.

  19. MELATONIN ENHANCES JUNCTIONAL TRANSFER IN NORMAL C3H/1OT1/2 CELLS

    EPA Science Inventory

    There is strong evidence that pineal melatonin is involved in controlling neoplastic processes. e have reported that physiological, but not pharmacological or subphysiological, concentrations of melatonin enhance intercellular communication in normal C3H/1OT1/2 fibroblasts. ap ju...

  20. 12 CFR 563b.300 - What must happen before OTS declares my offering circular effective?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... offering circular effective? 563b.300 Section 563b.300 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Offering Circular § 563b.300 What must happen before OTS declares my offering circular effective? (a) You must prepare...

  1. 12 CFR 563b.300 - What must happen before OTS declares my offering circular effective?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... offering circular effective? 563b.300 Section 563b.300 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY CONVERSIONS FROM MUTUAL TO STOCK FORM Standard Conversions Offering Circular § 563b.300 What must happen before OTS declares my offering circular effective? (a) You must prepare...

  2. Optimal Diphthongs: An OT Analysis of the Acquisition of Spanish Diphthongs

    ERIC Educational Resources Information Center

    Krause, Alice

    2013-01-01

    This dissertation investigates the acquisition of Spanish diphthongs by adult native speakers of English. The following research questions will be addressed: 1) How do adult native speakers of English pronounce sequences of two vowels in their L2 Spanish at different levels of acquisition? 2) Can OT learnability models, specifically the GLA,…

  3. 12 CFR 555.300 - Must I inform OTS before I use electronic means or facilities?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... transactional web site. A transactional web site is an Internet site that enables users to conduct financial... 12 Banks and Banking 6 2014-01-01 2012-01-01 true Must I inform OTS before I use electronic means or facilities? 555.300 Section 555.300 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT...

  4. Simulation of aerosol distributions and radiative forcing for INDOEX: Regional climate impacts

    NASA Astrophysics Data System (ADS)

    Collins, William D.; Rasch, Phillip J.; Eaton, Brian E.; Fillmore, David W.; Kiehl, Jeffrey T.; Beck, C. Trevor; Zender, Charles S.

    2002-10-01

    The direct radiative forcing by aerosols over the Indian Ocean region is simulated for the Indian Ocean Experiment (INDOEX) Intensive Field Phase during Spring 1999. The forcing is calculated for the top-of-atmosphere (TOA), surface, and atmosphere by differencing shortwave fluxes computed with and without aerosols. The calculation includes the effects of sea-salt, sulfate, carbonaceous, and soil-dust aerosols. The aerosol distributions are obtained from a global aerosol simulation including assimilation of satellite retrievals of aerosol optical thickness (AOT). The time-dependent, three-dimensional aerosol distributions are derived with a chemical transport model driven with meteorological analyses for this period. The surface albedos are obtained from a land-surface model forced with an identical meteorological analysis and satellite-derived rainfall and insolation. These calculations are consistent with in situ observations of the surface insolation over the central Indian Ocean and with satellite measurements of the reflected shortwave radiation. The calculations show that the surface insolation under clear skies is reduced by as much as 40 W/m2 over the Indian subcontinent by natural and anthropogenic aerosols. This reduction in insolation is accompanied by an increase in shortwave flux absorbed in the atmosphere by 25 W/m2. The inclusion of clouds in the calculations changes the direct effect by less than 2 W/m2 over the Indian subcontinent, although the reduction is much larger over China. The magnitude of the difference between all-sky and clear-sky forcing is quite sensitive to the three-dimensional spatial relationship between the aerosol and cloud fields, and other estimates of the difference for the INDOEX Intensive Field Phase are as large as 5 W/m2.

  5. Assessing Aerosol Mixed Layer Heights from the NASA Larc Airborne High Spectral Resolution Lidar (HSRL) during the Discover-AQ Field Campaigns

    NASA Astrophysics Data System (ADS)

    Scarino, A. J.; Ferrare, R. A.; Burton, S. P.; Hostetler, C. A.; Hair, J. W.; Rogers, R. R.; Berkoff, T.; Sawamura, P.; Collins, J. E., Jr.; Seaman, S. T.; Cook, A. L.; Harper, D. B.; Follette-Cook, M. B.; daSilva, A.; Randles, C. A.

    2014-12-01

    The first- and second-generation NASA airborne High Spectral Resolution Lidars (HSRL-1 and HSRL-2) have been deployed on board the NASA Langley Research Center King Air aircraft during the Deriving Information on Surface Conditions from Column and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) field campaigns. These included deployments during July 2011 over Washington, D.C. and Baltimore, MD, during January and February 2013 over the San Joaquin Valley of California, during September 2013 over Houston, TX and during July and August 2014 over Denver, CO. Measurements of aerosol extinction, backscatter, and depolarization are available from both HSRL-1 and HSRL-2 in coordination with other participating research aircraft and ground sites. These measurements constitute a diverse data set for use in characterizing the spatial and temporal distribution of aerosols, aerosol optical thickness (AOT), as well as the mixed layer (ML) height. Analysis of the ML height at these four locations is presented, including temporal and horizontal variability and comparisons between land and water, including the Chesapeake Bay and Galveston Bay. Using the ML heights, the distribution of AOT relative to the ML heights is determined, which is relevant for assessing the long-range transport of aerosols. The ML heights are also used to help relate column AOT measurements and extinction profiles to surface PM2.5 concentrations. The HSRL ML heights are also used to evaluate the performance in simulating the temporal and spatial variability of ML heights from both chemical regional models and global forecast models.

  6. 12 CFR 502.27 - How does OTS determine the risk/complexity component for a savings and loan holding company?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... loan holding company? (a) OTS computes the risk/complexity component for responsible savings and loan... entities. (c) OTS uses the following chart to compute the risk/complexity component under this section. OTS... Billion (d) To compute your risk/complexity component, find the row in the appropriate schedule...

  7. 33 CFR 150.445 - When is oil in a single point mooring-oil transfer system (SPM-OTS) displaced with water?

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... mooring-oil transfer system (SPM-OTS) displaced with water? 150.445 Section 150.445 Navigation and...-OTS) displaced with water? (a) The oil in an SPM-OTS must be displaced with water, and the valve at... section is waived if port officials can demonstrate to the Officer in Charge of Marine Inspection that...

  8. Dust events and their influence on aerosol optical properties over Jaipur in Northwestern India.

    PubMed

    Verma, Sunita; Payra, Swagata; Gautam, Ritesh; Prakash, Divya; Soni, Manish; Holben, Brent; Bell, Shaun

    2013-09-01

    In this study, we systematically document the link between dust episodes and local scale regional aerosol optical properties over Jaipur located in the vicinity of Thar Desert in the northwestern state of Rajasthan. The seasonal variation of AOT(500 nm) (aerosol optical thickness) shows high values (0.51 ± 0.18) during pre-monsoon (dust dominant) season while low values (0.36 ± 0.14) are exhibited during winter. The Ångström wavelength exponent has been found to exhibit low value (<0.25) indicating relative dominance of coarse-mode particles during pre-monsoon season. The AOT increased from 0.36 (Aprilmean) to 0.575 (May-June(mean)). Consequently, volume concentration range increases from April through May-June followed by a sharp decline in July during the first active phase of the monsoon. Significantly high dust storms were observed over Jaipur as indicated by high values of single scattering albedo (SSA(440 nm) = 0.89, SSA(675 nm) = 0.95, SSA870 nm = 0.97, SSA(1,020 nm) = 0.976) than the previously reported values over IGP region sites. The larger SSA values (more scattering aerosol), especially at longer wavelengths, is due to the abundant dust loading, and is attributed to the measurement site's proximity to the Thar Desert. The mean and standard deviation in SSA and asymmetry parameter during pre-monsoon season over Jaipur is 0.938 ± 0.023 and 0.712 ± 0.017 at 675 nm wavelength, respectively. Back-trajectory air mass simulations suggest Thar Desert in northwestern India as the primary source of high aerosols dust loading over Jaipur region as well as contribution by long-range transport from the Arabian Peninsula and Middle East gulf regions, during pre-monsoon season. PMID:23397540

  9. Intercomparison of satellite aerosol retrieval algorithms based on the simulated measurements of the intensity and polarization of reflected solar light for various types of underlying surfaces

    NASA Astrophysics Data System (ADS)

    Kokhanovsky, Alexander

    2014-05-01

    Atmospheric aerosol has a profound influence on climate, the global cloud field, and human health. Therefore, the microphysical (size and shape of particles, chemical composition, and concentration) and optical (optical thickness, single scattering albedo) properties of atmospheric aerosol have been thoroughly studied using the ground-based and satellite observation systems. The main optical parameter is aerosol optical thickness (AOT). AOT can be derived from measurements of direct solar light by a sun-photometer positioned on the ground, a ship, or an aircraft. Simultaneously, AOT can be derived using an optical instrument orbiting the planet. The ground measurements provide the most accurate values of the AOT, as they provide a direct measure of the attenuation of solar radiation. Satellite measurements require the development of the complex retrieval software, because the satellite signal contains both contribution from the surface and atmospheric aerosol. The contributions of molecular scattering and absorption must be accounted for as well. There have been numerous attempts to compare the spectral AOT derived from the ground and satellite measurements, with the accuracy of satellite retrievals is usually checked against ground measurements collocated in time and space. However, such inter-comparisons cannot be perfect because the direct solar light beam attenuation measurements from the ground and reflected solar light measurements provide different spatial sampling of atmosphere. This is not a big issue in the ideal case of a cloudless sky with homogeneously distributed aerosol particles. However, in practice, some residual clouds (e.g., Cirrus) or contrails can influence the signal measured on the ground and also from orbit. Moreover, atmospheric aerosol is not always homogeneously distributed in space. This will make the direct inter-comparison of both techniques difficult. Yet another possibility is to compare results of retrievals from different

  10. More evidence on the control of reverse micelles sizes. Combination of different techniques as a powerful tool to monitor AOT reversed micelles properties.

    PubMed

    Durantini, Andrés M; Falcone, R Darío; Silber, Juana J; Correa, N Mariano

    2013-04-11

    In this work, we have investigated the behavior of 4-aminophthalimide (4-AP) in solvent mixtures of ethyl lactate (EL)- water and EL-n-heptane and in reversed micelles (RMs) media made of EL-water/sodium 1,4-bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane. We have used dynamics light scattering (DLS) and absorption, steady-state and time-resolved emission (TRES) techniques. 4-AP is a very interesting and unique molecule used to study preferential solvation in water mixtures since its emission profile changes dramatically when its sphere shell is solvated by water molecules. Thus, in homogeneous media 4-AP is strongly solvated by water in the EL-water mixture and by EL in the EL-n-heptane mixture, results that show the importance of the hydrogen bonding in the 4-AP solvation. We were motivated by this feature of 4-AP and have used it to monitor properties in AOT RMs. Thus, we use 4-AP spectroscopic behavior in conjunction with DLS technique to reveal the location of each polar solvent of the mixture encapsulated within the RMs media. We found that in the EL-water/AOT/n-heptane RMs the results strongly depend on the amount of water dissolved. Below W0 = [water]/[AOT] = 5, there are no reversed micelles and EL, water, AOT and n-heptane forms a nonstructured mixture. For W0 values between 5 and 10, the droplet sizes are independent of the EL content because of its strong intermolecular interactions forms an EL polar core and only water is found at the interface. For W0 values higher than 10, the droplets size increase with the EL content and EL molecules are detected at the AOT RMs interface. We inferred that the RMs sizes will change only if the polar solvent encapsulated interacts with the interface changing the surfactant packing parameter. Then, we can assume that it is possible to create RMs with solvents that do not interact with the interface but can be encapsulated in the polar core. These results, give evidence that expand the knowledge about which are the

  11. Satellite-derived aerosol radiative forcing from the 2004 British Columbia wildfires

    USGS Publications Warehouse

    Guo, S.; Leighton, H.

    2008-01-01

    The British Columbia wildfires of 2004 was one of the largest wildfire events in the last ten years in Canada. Both the shortwave and longwave smoke aerosol radiative forcing at the top-of-atmosphere (TOA) are investigated using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Clouds and the Earth's Radiant Energy System (CERES) instruments. Relationships between the radiative forcing fluxes (??F) and wildfire aerosol optical thickness (AOT) at 0.55 ??m (??0.55) are deduced for both noontime instantaneous forcing and diurnally averaged forcing. The noontime averaged instantaneous shortwave and longwave smoke aerosol radiative forcing at the TOA are 45.8??27.5 W m-2 and -12.6??6.9 W m-2, respectively for a selected study area between 62??N and 68??N in latitude and 125??W and 145??W in longitude over three mainly clear-sky days (23-25 June). The derived diurnally averaged smoke aerosol shortwave radiative forcing is 19.9??12.1 W m-2 for a mean ??0.55 of 1.88??0.71 over the same time period. The derived ??F-?? relationship can be implemented in the radiation scheme used in regional climate models to assess the effect of wildfire aerosols.

  12. Effects of Spatial Resolution on the Simulated Dust Aerosol Lifecycle: Implications for Dust Event Magnitude and Timing in the NASA GEOS-5 AGCM

    NASA Technical Reports Server (NTRS)

    Nowottnick, E.; Colarco, Peter R.; daSilva, A.

    2011-01-01

    The NASA GEOS-5 atmospheric transport model simulates global aerosol distributions with an online aerosol module. GEOS-5 may be run at various horizontal spatial resolutions depending on the research application. For example, long integration climate simulations are typically run at 2 deg or 1 deg grid spacing, whereas aerosol reanalysis and forecasting applications may be performed at O.5 deg or 0.25 deg resolutions. In this study, we assess the implications of varying spatial resolution on the simulated aerosol fields, with a particular focus on dust. Dust emissions in GEOS-5 are calculated with one of two parameterizations, one based on the Goddard Chemistry, Aerosol, Radiation, and Transport (GO CART) model and another based on the Dust Entrainment and Deposition (DEAD) model. Emission fluxes are parameterized in terms of the surface wind speed, either the 10-m (GO CART) or friction (DEAD) wind speed. We consider how surface wind speeds and thus the dust emission rates are a function of the model spatial resolution. We find that spatial resolution has a significant effect on the magnitude of dust emissions, as higher resolution versions of the model have typically higher surface wind speeds. Utilizing space-borne observations from MISR, MODIS, and CALIOP, we find that simulated Aerosol Optical Thickness (AOT) distributions respond differently to spatial resolution over the African and Asian source regions, highlighting the need to regional dust emission tuning. When compared to ground-based observations from AERONET, we found improved timing of dust events with as spatial resolution was increased. In an attempt to improve the representation of the dust aerosol lifecycle at coarse resolutions, we found that incorporating the effects of sub-grid wind variability in a course resolution simulation led to improved agreement with observed AOT magnitudes, but did not impact the timing of simulated dust events.

  13. Four dimensional variational assimilation of in-situ and remote-sensing aerosol data

    NASA Astrophysics Data System (ADS)

    Nieradzik, L. P.; Elbern, H.

    2012-04-01

    Aerosols play an increasingly important role in atmospheric modelling. They have a strong influence on the radiative transfer balance and a significant impact on human health. Their origin is various and so are its effects. Most of the measurement sites in Europe account for an integrated aerosol load PMx (Particulate Matter of less than x μm in diameter) which does not give any qualitative information on the composition of the aerosol. Since very different constituents contribute to PMx, like e.g. mineral dust derived from desert storms or sea salt, it is necessary to make aerosol forecasts not only of load, but also type resolved. The method of four dimensional variational data assimilation (4Dvar) is a widely known technique to enhance forecast skills of CTMs (Chemistry-Transport-Models) by ingesting in-situ and, especially, remote-sensing measurements. The EURAD-IM (EURopean Air pollution Dispersion - Inverse Model), containing a full adjoint gas-phase model, has been expanded with an adjoint of the MADE (Modal Aerosol Dynamics model for Europe) to optimise initial and boundary values for aerosols using 4Dvar. A forward and an adjoint radiative transfer model is driven by the EURAD-IM as mapping between BLAOT (Boundary Layer Aerosol Optical Thickness) and internal aerosol species. Furthermore, its condensation scheme has been bypassed by an HDMR (High-Dimensional-Model-Representation) to ensure differentiability. In this study both in-situ measured PMx as well as satellite retrieved aerosol optical thicknesses have been assimilated and the effect on forecast performance has been investigated. The source of BLAOT is the aerosol retrieval system SYNAER (SYNergetic AErosol Retrieval) from DLR-DFD that retrieves AOT by making use of both AATSR/SCIAMACHY and AVHRR/GOME-2 data respectively. Its strengths are a large spatial coverage, near real-time availability, and the classification of five intrinsic aerosol species, namely water-solubles, water-insolubles, soot

  14. DO3SE model applicability and O3 flux performance compared to AOT40 for an O3-sensitive tropical tree species (Psidium guajava L. 'Paluma').

    PubMed

    Assis, Pedro I L S; Alonso, Rocío; Meirelles, Sérgio T; Moraes, Regina M

    2015-07-01

    Phytotoxic ozone (O3) levels have been recorded in the Metropolitan Region of São Paulo (MRSP). Flux-based critical levels for O3 through stomata have been adopted for some northern hemisphere species, showing better accuracy than with accumulated ozone exposure above a threshold of 40 ppb (AOT40). In Brazil, critical levels for vegetation protection against O3 adverse effects do not exist. The study aimed to investigate the applicability of O3 deposition model (Deposition of Ozone for Stomatal Exchange (DO3SE)) to an O3-sensitive tropical tree species (Psidium guajava L. 'Paluma') under the MRSP environmental conditions, which are very unstable, and to assess the performance of O3 flux and AOT40 in relation to O3-induced leaf injuries. Stomatal conductance (g s) parameterization for 'Paluma' was carried out and used to calculate different rate thresholds (from 0 to 5 nmol O3 m(-2) projected leaf area (PLA) s(-1)) for the phytotoxic ozone dose (POD). The model performance was assessed through the relationship between the measured and modeled g sto. Leaf injuries were analyzed and associated with POD and AOT40. The model performance was satisfactory and significant (R (2) = 0.56; P < 0.0001; root-mean-square error (RMSE) = 116). As already expected, high AOT40 values did not result in high POD values. Although high POD values do not always account for more injuries, POD0 showed better performance than did AOT40 and other different rate thresholds for POD. Further investigation is necessary to improve our model and also to check if there is a critical level of ozone in which leaf injuries arise. The conclusion is that the DO3SE model for 'Paluma' is applicable in the MRSP as well as in temperate regions and may contribute to future directives. PMID:25772875

  15. Steady-state and time-resolved fluorescence studies of bis(2-ethylhexyl) sodium succinate (AOT) reverse micelles in supercritical ethane

    SciTech Connect

    Jing Zhang; Bright, F.V.

    1992-06-25

    The properties of bis(2-ethylhexyl) sodium sulfosuccinate (AOT) reverse micelles in supercritical ethane (T{sub c} = 32.3 {degrees}C, P{sub c} = 48.8 bar) have been investigated by fluorescence spectroscopy. Two different fluorophores (1-anilino-8-naphthalenesulfonic acid (1,8-ANS) and 6-propionyl-2-(dimethylamino)naphthalene (PRODAN)) were used to probe the microenvironment of this system. Probe and surfactant concentrations, temperature, and fluid density were found to have significant in fluence on the reverse micelle dynamics. The change in fluorescence intensity with density is rationalized by changes in the partition coefficient between the probe and the AOT micelle. This is also consistent with density-dependent changes of the emission spectral contours. The 1,8-ANS decay kinetics were fit best by two discrete components, indicating that the probe is located simultaneously in two different AOT domains. The PRODAN decay too is best fit with a two-component model; however, one of the decay terms is Lorentzian distributed and the other is discrete. The distributed component represents PRODAN located simultaneously in an ensemble of AOT domains. The shorter-lived, discrete component correlates well with PRODAN free in the ethane continuous phase. By using the lifetime information we determined the density dependent {Delta}H{degrees} and {Delta}S{degrees} for the probe-AOT-ethane equilibrium. In turn, we find that the equilibrium constant (K{sub eq}) decreases with increased continuous phase density. However, the {Delta}H{degrees} for this process becomes more favorable with increasing density. The reason for the decrease in K{sub eq} lies in the {Delta}S{degrees} term. Initially, {Delta}S{degrees} is positive (favorable), but eventually it becomes quite negative at elevated densities. Thus, entropy governs (mostly) this particular equilibrium process. 87 refs., 13 figs., 4 tabs.

  16. Global Atmospheric Aerosol Modeling

    NASA Technical Reports Server (NTRS)

    Hendricks, Johannes; Aquila, Valentina; Righi, Mattia

    2012-01-01

    Global aerosol models are used to study the distribution and properties of atmospheric aerosol particles as well as their effects on clouds, atmospheric chemistry, radiation, and climate. The present article provides an overview of the basic concepts of global atmospheric aerosol modeling and shows some examples from a global aerosol simulation. Particular emphasis is placed on the simulation of aerosol particles and their effects within global climate models.

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    variation of O2-O2 SCD and continuum reflectance as a function of effective cloud parameters in case of low effective cloud fraction values is requested for applying an aerosol correction. The updates of the OMI O2-O2 cloud algorithm, based on the scheduled new OMI cloud LUT, will be presented in terms of impacts of the effective cloud retrievals and reduced biases of tropospheric NO2 columns over cloud-free scenes dominated by aerosols in China. A 2nd approach is investigated, assuming a more explicit aerosol correction. Previous analyses pointed out that the O2-O2 spectra contain information about aerosols: the continuum reflectance is primarily constrained by the Aerosol Optical thickness (AOT) while the O2-O2 Slant Column Density (SCD) mostly results from the combination of AOT and aerosols altitude. We have developed a first prototype algorithm allowing to retrieve information about AOT and aerosol altitude from the O2-O2 DOAS fit. We will discuss preliminary sensitivities and the potential accuracy of the associated explicit aerosol correction, without the use of effective cloud parameters.

  18. Coherent uncertainty analysis of aerosol measurements from multiple satellite sensors

    NASA Astrophysics Data System (ADS)

    Petrenko, M.; Ichoku, C.

    2013-02-01

    Aerosol retrievals from multiple spaceborne sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, and SeaWiFS - altogether, a total of 11 different aerosol products - were comparatively analyzed using data collocated with ground-based aerosol observations from the Aerosol Robotic Network (AERONET) stations within the Multi-sensor Aerosol Products Sampling System (MAPSS, http://giovanni.gsfc.nasa.gov/mapss/ and http://giovanni.gsfc.nasa.gov/aerostat/). The analysis was performed by comparing quality-screened satellite aerosol optical depth or thickness (AOD or AOT) retrievals during 2006-2010 to available collocated AERONET measurements globally, regionally, and seasonally, and deriving a number of statistical measures of accuracy. We used a robust statistical approach to detect and remove possible outliers in the collocated data that can bias the results of the analysis. Overall, the proportion of outliers in each of the quality-screened AOD products was within 12%. Squared correlation coefficient (R2) values of the satellite AOD retrievals relative to AERONET exceeded 0.6, with R2 for most of the products exceeding 0.7 over land and 0.8 over ocean. Root mean square error (RMSE) values for most of the AOD products were within 0.15 over land and 0.09 over ocean. We have been able to generate global maps showing regions where the different products present advantages over the others, as well as the relative performance of each product over different landcover types. It was observed that while MODIS, MISR, and SeaWiFS provide accurate retrievals over most of the landcover types, multi-angle capabilities make MISR the only sensor to retrieve reliable AOD over barren and snow/ice surfaces. Likewise, active sensing enables CALIOP to retrieve aerosol properties over bright-surface shrublands more accurately than the

  19. Coherent Uncertainty Analysis of Aerosol Measurements from Multiple Satellite Sensors

    NASA Technical Reports Server (NTRS)

    Petrenko, M.; Ichoku, C.

    2013-01-01

    Aerosol retrievals from multiple spaceborne sensors, including MODIS (on Terra and Aqua), MISR, OMI, POLDER, CALIOP, and SeaWiFS altogether, a total of 11 different aerosol products were comparatively analyzed using data collocated with ground-based aerosol observations from the Aerosol Robotic Network (AERONET) stations within the Multi-sensor Aerosol Products Sampling System (MAPSS, http://giovanni.gsfc.nasa.gov/mapss/ and http://giovanni.gsfc.nasa.gov/aerostat/). The analysis was performed by comparing quality-screened satellite aerosol optical depth or thickness (AOD or AOT) retrievals during 2006-2010 to available collocated AERONET measurements globally, regionally, and seasonally, and deriving a number of statistical measures of accuracy. We used a robust statistical approach to detect and remove possible outliers in the collocated data that can bias the results of the analysis. Overall, the proportion of outliers in each of the quality-screened AOD products was within 12%. Squared correlation coefficient (R2) values of the satellite AOD retrievals relative to AERONET exceeded 0.6, with R2 for most of the products exceeding 0.7 over land and 0.8 over ocean. Root mean square error (RMSE) values for most of the AOD products were within 0.15 over land and 0.09 over ocean. We have been able to generate global maps showing regions where the different products present advantages over the others, as well as the relative performance of each product over different landcover types. It was observed that while MODIS, MISR, and SeaWiFS provide accurate retrievals over most of the landcover types, multi-angle capabilities make MISR the only sensor to retrieve reliable AOD over barren and snow / ice surfaces. Likewise, active sensing enables CALIOP to retrieve aerosol properties over bright-surface shrublands more accurately than the other sensors, while POLDER, which is the only one of the sensors capable of measuring polarized aerosols, outperforms other sensors in

  20. Changes in the bending modulus of AOT based microemulsions induced by the incorporation of polymers in the water core.

    PubMed

    Kuttich, Björn; Grefe, Ann-Kathrin; Stühn, Bernd

    2016-08-14

    The bending modulus κ is known to be a crucial parameter for the stability of the droplet phase in microemulsion systems. For AOT based water in oil microemulsions the bending modulus of the surfactant has values close to kBT but can be influenced by the presence of polymers. In this work we focus on the water soluble polymer polyethylene glycol and how it influences the bending modulus. An increase by a factor of three is found. For the correct evaluation of the bending modulus via percolation temperatures and droplet radii, thus by dielectric spectroscopy and small angle X-ray scattering, the determination of the radii right at the percolation temperature is crucial as we will show, although it is often neglected. In order to precisely determine the droplet radii we will present a global fitting model which provides reliable results with a minimum number of free fitting parameters. PMID:27416768

  1. Structural changes of α-chymotrypsin in reverse micelles of AOT studied by steady state and transient state fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Andrade, Suzana M.; Costa, Silvia M. B.

    2001-05-01

    Time-resolved fluorescence of α-chymotrypsin (α-chym) solubilised in sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles was studied as a function of the amount of encapsulated water and initial pH. In reverse micelles the anionic interface leads to some conformational rearrangements at "pH ext" =10 due to electrostatic interactions with the ionised groups of α-chym. The data point to the protein's location in a bulk water environment, which accounts for its high stability in these reverse micelles and allows the distinction of three emitting classes of tryptophan residues within the protein's matrix. Fluorescence quenching results show that these residues are differently accessed to the quencher molecules used (acrylamide, succinimide and iodide) and are consistent with a mechanism of penetration for the interaction with the protein.

  2. Synthesis of Ag and AgI quantum dots in AOT-stabilized water-in-CO2 microemulsions.

    PubMed

    Liu, Juncheng; Raveendran, Poovathinthodiyil; Shervani, Zameer; Ikushima, Yutaka; Hakuta, Yukiya

    2005-03-01

    Silver and silver iodide nanocrystals have been synthesized in the water-in-CO(2) reverse microemulsions formed by the commonly used surfactant, sodium bis(2-ethylhexyl)sulfosuccinate (AOT), in the presence of 2,2,3,3,4,4,5,5-octafluoro-1-pentanol as cosurfactant. The nanometer-sized aqueous domains in the microemulsion cores not only act as nanoreactors, but the surfactant interfacial monolayer also helps the stabilization of the metal and semiconductor nanoparticles. The transmission electron microscopy results show that silver and silver iodide nanocrystals with average diameters of 6.0 nm (standard deviation, SD=1.3 nm) and 5.7 nm (SD=1.4 nm), respectively, were formed. The results indicate that the method can be utilized as a general and economically viable approach for the synthesis of metal and semiconductor quantum dots in environmentally benign supercritical carbon dioxide. PMID:15685712

  3. Aerosol gels

    NASA Technical Reports Server (NTRS)

    Sorensen, Christopher M. (Inventor); Chakrabarti, Amitabha (Inventor); Dhaubhadel, Rajan (Inventor); Gerving, Corey (Inventor)

    2010-01-01

    An improved process for the production of ultralow density, high specific surface area gel products is provided which comprises providing, in an enclosed chamber, a mixture made up of small particles of material suspended in gas; the particles are then caused to aggregate in the chamber to form ramified fractal aggregate gels. The particles should have a radius (a) of up to about 50 nm and the aerosol should have a volume fraction (f.sub.v) of at least 10.sup.-4. In preferred practice, the mixture is created by a spark-induced explosion of a precursor material (e.g., a hydrocarbon) and oxygen within the chamber. New compositions of matter are disclosed having densities below 3.0 mg/cc.

  4. Analysis of interfacial and micellar behavior of sodium dioctyl sulphosuccinate salt (AOT) with zwitterionic surfactants in aqueous media.

    PubMed

    Mahajan, Rakesh Kumar; Sharma, Rabia

    2011-11-01

    The interfacial and bulk properties of mixtures of the anionic surfactant (dioctyl sulphosuccinate sodium salt, AOT) with zwitterionic surfactants 3-(N,N-dimethyldodecylammonio) propane sulfonate (DPS), 3-(N,N-dimethyltetradecylammonio) propane sulfonate (TPS), 3-(N,N-dimethylhexadecylammonio) propane sulfonate (HPS) have been studied employing surface tension, fluorescence, and viscometric techniques in aqueous media at 25 °C. It is observed that these mixtures exhibit synergism and these synergistic interactions increase with the enhancement of the hydrocarbon chain of the zwitterionic surfactant. The various physicochemical properties such as critical micelle concentration (cmc), surface excess concentration (Г(max)), minimum area per molecule (A(min)), aggregation number (N(agg)), interaction parameters (β(σ), β(m)), and thermodynamic parameters such as standard Gibbs free energy of adsorption (ΔG(ads)(o)), excess free energy of micellization (ΔG(ex)), and standard Gibbs free energy of micellization (ΔG(m)(o)) have been evaluated. The negative values of ΔG(m)(o) and ΔG(ads)(o) show that the micelle formation and adsorption of surfactant at the air/solution interface is energetically favorable, while a negative value of ΔG(ex) ensures stability of the mixed micelles formed. The Regular Solution Approximation, Motomura and Rosen's approaches have been used to explain and compare the results. The packing parameter (p) ensures the formation of vesicles or bilayers for AOT+DPS/TPS mixtures, which can potentially be used as delivery agents for industrial applications. PMID:21843891

  5. Aerosol typing - key information from aerosol studies

    NASA Astrophysics Data System (ADS)

    Mona, Lucia; Kahn, Ralph; Papagiannopoulos, Nikolaos; Holzer-Popp, Thomas; Pappalardo, Gelsomina

    2016-04-01

    Aerosol typing is a key source of aerosol information from ground-based and satellite-borne instruments. Depending on the specific measurement technique, aerosol typing can be used as input for retrievals or represents an output for other applications. Typically aerosol retrievals require some a priori or external aerosol type information. The accuracy of the derived aerosol products strongly depends on the reliability of these assumptions. Different sensors can make use of different aerosol type inputs. A critical review and harmonization of these procedures could significantly reduce related uncertainties. On the other hand, satellite measurements in recent years are providing valuable information about the global distribution of aerosol types, showing for example the main source regions and typical transport paths. Climatological studies of aerosol load at global and regional scales often rely on inferred aerosol type. There is still a high degree of inhomogeneity among satellite aerosol typing schemes, which makes the use different sensor datasets in a consistent way difficult. Knowledge of the 4d aerosol type distribution at these scales is essential for understanding the impact of different aerosol sources on climate, precipitation and air quality. All this information is needed for planning upcoming aerosol emissions policies. The exchange of expertise and the communication among satellite and ground-based measurement communities is fundamental for improving long-term dataset consistency, and for reducing aerosol type distribution uncertainties. Aerosol typing has been recognized as one of its high-priority activities of the AEROSAT (International Satellite Aerosol Science Network, http://aero-sat.org/) initiative. In the AEROSAT framework, a first critical review of aerosol typing procedures has been carried out. The review underlines the high heterogeneity in many aspects: approach, nomenclature, assumed number of components and parameters used for the

  6. Computer software design description for the Treated Effluent Disposal Facility (TEDF), Project L-045H, Operator Training Station (OTS)

    SciTech Connect

    Carter, R.L. Jr.

    1994-11-07

    The Treated Effluent Disposal Facility (TEDF) Operator Training Station (OTS) is a computer-based training tool designed to aid plant operations and engineering staff in familiarizing themselves with the TEDF Central Control System (CCS).

  7. 12 CFR 502.29 - How does OTS determine the condition component for a savings and loan holding company?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... holding company structure) is a composite rating of 4 or 5, OTS will assess a charge under the condition... amount, the risk/complexity component, and any organizational form component. (b) For the purposes...

  8. 12 CFR 502.29 - How does OTS determine the condition component for a savings and loan holding company?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... holding company structure) is a composite rating of 4 or 5, OTS will assess a charge under the condition... amount, the risk/complexity component, and any organizational form component. (b) For the purposes...

  9. Droplet polydispersity and shape fluctuations in AOT [bis(2-ethylhexyl)sulfosuccinate sodium salt] microemulsions studied by contrast variation small-angle neutron scattering

    SciTech Connect

    Arleth, Lise; Pedersen, Jan Skov

    2001-06-01

    Microemulsions consisting of AOT water, and decane or iso-octane are studied in the region of the phase diagram where surfactant covered water droplets are formed. The polydispersity and shape fluctuations of the microemulsion droplets are determined and compared in the two different alkane types. Conductivity measurements show that there is a pronounced dependence of the temperature behavior of the microemulsion on the type of alkane used. In both cases the microemulsion droplets start to form larger aggregates when the temperature increases. But in the system with decane this aggregation temperature occurs at a temperature about 10{degree}C lower than in a similar system with iso-octane. Aggregation phenomena are avoided and the two systems are at approximately the same reduced temperature with respect to the aggregation temperature when the temperature of the AOT/D{sub 2}O/decane microemulsion is 10{degree}C and the temperature of the AOT/D{sub 2}O/iso-octane microemulsion is 20{degree}C. Contrast variation small-angle neutron scattering measurements are performed at these temperatures on systems with volume fractions of 5% D{sub 2}O+AOT by varying the scattering length density of the alkane. The small-angle scattering for 11 different contrasts evenly distributed around the match points are studied for each sample. The scattering data for the different contrasts are analyzed using a molecular constrained model for ellipsoidal droplets of water covered by AOT, interacting as polydisperse hard spheres. All contrasts are fitted simultaneously by taking the different contrast factors into account. The analysis show that at the same reduced temperature with respect to the aggregation temperature the droplet size, polydispersity index, the size of the shape fluctuations are similar in the two systems. A polydispersity index ({sigma}/R of the Gaussian size distribution) of 16% and an average axis ratio of the droplets of 1.56 is found in the AOT/D{sub 2}O

  10. Variability of aerosol optical thickness and atmospheric turbidity in Tunisia

    NASA Astrophysics Data System (ADS)

    Masmoudi, M.; Chaabane, M.; Medhioub, K.; Elleuch, F.

    The aerosol optical thickness (AOT) τa computed from the spectral sun photometer in Thala (Tunisia) exhibited variability ranging from approximately 0.03 to greater than 2.0 at 870 nm for March-October 2001. These measurements are compared to the aerosol optical thickness computed in Ouagadougou (Burkina-Faso), Banizoumbou (Niger), IMC Oristano (Sardinia) and Rome Tor Vergata (Italy). Analysis of τa data from this observation network suggests that there is a high temporal and spatial variability of τa in the different sites. The Angström wavelength exponent α was found to vary with the magnitude of the aerosol optical thickness, with values as high as 1.5 for very low τa, and values of -0.1 for high τa situations. The relationship between the two parameters τa and α is investigated. Values of the turbidity coefficient β have been determined in Thala (Tunisia) for 8 months in 2001 based on a direct fitting method of the Angström power law expression using sun photometer data. The monthly averaged values of the turbidity coefficient β vary between 0.15 and 0.33. The months of July and October experienced the highest turbidity, while April experienced the lowest aerosol loading on average. The turbidity shows a maximum and minimum values for the Southwest and the Northwest wind directions, respectively. The single scattering albedo ωo for the 870 nm wavelength obtained from solar aureole data in Thala is analysed according to the particles' origin.

  11. Asiago observation of the OT of GRB150413A detected by MASTER

    NASA Astrophysics Data System (ADS)

    Tomasella, L.; Benetti, S.; Cappellaro, E.; Elias-Rosa, N.; Ochner, P.; Pastorello, A.; Tartaglia, L.; Terreran, G.; Turatto, M.

    2015-04-01

    In the framework of the Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841), we have spectroscopically observed the OT of GRB150413A detected by MASTER (Atel #7381) with the Asiago 1.82 m Copernico Telescope (+AFOSC; range 340-820 nm; resolution 1.4 nm), on 20150413.87 UT, that is about 7.0h after detection.

  12. 78 FR 76768 - Removal of Transferred OTS Regulations Regarding Disclosure and Reporting of CRA-Related...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-19

    ... on July 6, 2011.\\2\\ \\2\\ 76 FR 39247 (July 6, 2011). Although section 312(b)(2)(B)(i)(II) of the Dodd... rescinding them, as appropriate. \\3\\ 76 FR 47652 (Aug. 5, 2011). One of the OTS rules transferred to the FDIC...)(1). \\8\\ 66 FR 2052 (Jan. 10, 2001). \\9\\ Id. Section 48 of the FDI Act, created by section 711 of...

  13. Asiago spectroscopic classification of MASTER OT J211223.35+144645.1

    NASA Astrophysics Data System (ADS)

    Ascenzi, S.; Yang, S.; Tomasella, L.; Benetti, S.; Cappellaro, E.; Pastorello, A.; Elias-Rosa, N.; Ochner, P.; Tartaglia, L.; Terreran, G.; Turatto, M.

    2016-06-01

    The Asiago Transient Classification Program (Tomasella et al. 2014, AN, 335, 841) reports the spectroscopic classification of MASTER OT J211223.35+144645.1 (Atel #9174), discovered by MASTER-IAC auto-detection system (Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171) The observation was performed with the Asiago 1.82 m Copernico Telescope (+AFOSC; range 340-820 nm; resolution 1.4 nm).

  14. GLOBE Aerosol Field Campaign - U.S. Pilot Study 2016

    NASA Technical Reports Server (NTRS)

    Pippin, Margaret; Marentette, Christina; Bujosa, Robert; Taylor, Jessica; Lewis, Preston

    2016-01-01

    During the spring of 2016, from April 4 - May 27, sixteen GLOBE schools participated in the GLOBE Aerosol Field Campaign - U.S. Pilot Study. Thirteen teachers from these schools had previously participated in the NASA LEARN program (Long-term Experience in Authentic Research with NASA) where they were GLOBE trained in Atmosphere protocols, and engaged in 1-3 years of research under the mentorship of NASA scientists. Each school was loaned two aerosol instruments for the Campaign duration, either 2 GLOBE sun photometers, 2 Calitoo sun photometers, or 1 of each. This allowed for students to make measurements side-by-side and in the case of the Calitoos, to compare AOT results immediately with each other for better consistency in data collection. Additionally, as part of the Field Campaign evaluation, multiple instruments allow for an assessment of the ease of use of each instrument for grade level of students, whether in middle school or high school. Before the Campaign, all GLOBE and Calitoo instruments were 'checked out' against an AERONET, then checked again upon return after the Campaign. By examining all data, before, during and after the Campaign, this gives an indication of instrument performance and proficiency obtained by the students. Support was provided to each teacher and their students at the level requested, via email, phone or video conferencing.

  15. Aerosol mobility size spectrometer

    DOEpatents

    Wang, Jian; Kulkarni, Pramod

    2007-11-20

    A device for measuring aerosol size distribution within a sample containing aerosol particles. The device generally includes a spectrometer housing defining an interior chamber and a camera for recording aerosol size streams exiting the chamber. The housing includes an inlet for introducing a flow medium into the chamber in a flow direction, an aerosol injection port adjacent the inlet for introducing a charged aerosol sample into the chamber, a separation section for applying an electric field to the aerosol sample across the flow direction and an outlet opposite the inlet. In the separation section, the aerosol sample becomes entrained in the flow medium and the aerosol particles within the aerosol sample are separated by size into a plurality of aerosol flow streams under the influence of the electric field. The camera is disposed adjacent the housing outlet for optically detecting a relative position of at least one aerosol flow stream exiting the outlet and for optically detecting the number of aerosol particles within the at least one aerosol flow stream.

  16. Solar dimming and urban aerosol distribution in New York Metropolitan area

    NASA Astrophysics Data System (ADS)

    Hannon, P.; Liepert, B.; Chillrud, S. N.

    2004-12-01

    One impact of human activities on the urban and suburban environment is the dimming of sunlight due to urban air pollution and intensified haze. The spreading of urban aerosol and the optical efficiency depends on the size distribution of the particles and the vertical distribution. Reduced transparency of the atmosphere leads to an increase in scattered light compared to direct sunlight and an overall reduced total solar flux at the surface due to absorption in the atmosphere and backscattering of light to space. The modified solar flux cools the surface and suppresses evaporation and turbulent mass exchange in urban and suburban areas. Increase in diffuse sunlight can also have a positive effect on plant productivity due to increased actinic flux. Hence consequences for the biogeochemical cycles can be expected in urban and suburban areas. The quantification and variability of these effects were investigated in a pilot project in summer 2003 and 2004 where measurements of Aerosol Optical Thickness (AOT) at several wavelengths and particle number concentration for multiple size ranges were made in pilot fashion with the initial goal of better understanding horizontal and vertical distribution of aerosols near a major metropolitan center. Large spatial variability of atmospheric transparency in the New York Metropolitan area was observed in transects through New York City and Long Island to New Jersey in a field campaign in July 2003. Vertical profiles of AOT and particle number concentration were collected on board hot-air balloon flights in July 2004 that were launched from rural/suburban New Jersey. One evening flight was made in clear conditions and 4 evening flights where made under varying hazy conditions with the sunphotometer looking west. One sunrise flight was made in hazy conditions with the sunphotometer looking east through the city. Here we highlight a few results from two evening flights; additional data and plans of future work will be discussed in

  17. Satellite Characterization of Fire Emissions of Aerosols and Gases Relevant to Air-Quality Modeling

    NASA Astrophysics Data System (ADS)

    Ichoku, C. M.; Ellison, L.; Yue, Y.; Wang, J.

    2015-12-01

    Because of the transient and widespread nature of wildfires and other types of open biomass burning, satellite remote sensing has become an indispensable technique for characterizing their smoke emissions for modeling applications, especially at regional to global scales. Fire radiative energy (FRE), whose instantaneous rate of release or fire radiative power (FRP) is measurable from space, has been found to be proportional to both the biomass consumption and emission of aerosol particulate matter. We have leveraged this relationship to generate a global, gridded smoke-aerosol emission coefficients (Ce) dataset based on FRP and aerosol optical thickness (AOT) measurements from the MODIS sensors aboard the Terra and Aqua satellites. Ce is a simple coefficient to convert FRE to smoke aerosol emissions, in the same manner as traditional emission factors are used to convert burned biomass to emissions. The first version of this Fire Energetics and Emissions Research (FEER.v1) global gridded Ce product at 1°x1° resolution is available at http://feer.gsfc.nasa.gov/. Based on published emission ratios, the FEER.v1 Ce product for total smoke aerosol has also been used to generate similar products for specific fire-emitted aerosols and gases, including those that are regulated as 'criteria pollutants' under the US Environmental Protection Agency's National Ambient Air Quality Standards (NAAQS), such as particulate matter (PM) and carbon monoxide (CO). These gridded Ce products were used in conjunction with satellite measurements of FRP to derive emissions of several smoke constituents, which were applied to WRF-Chem fully coupled meteorology-chemistry-aerosol model simulations, with promising results. In this presentation, we analyze WRF-Chem simulations of surface-level concentrations of various pollutants based on FEER.v1 emission products to illustrate their value for air-quality modeling, particularly in parts of Africa and southeast Asia where ground-based air

  18. AEROSOL AND GAS MEASUREMENT

    EPA Science Inventory

    Measurements provide fundamental information for evaluating and managing the impact of aerosols on air quality. Specific measurements of aerosol concentration and their physical and chemical properties are required by different users to meet different user-community needs. Befo...

  19. Aerosols and environmental pollution

    NASA Astrophysics Data System (ADS)

    Colbeck, Ian; Lazaridis, Mihalis

    2010-02-01

    The number of publications on atmospheric aerosols has dramatically increased in recent years. This review, predominantly from a European perspective, summarizes the current state of knowledge of the role played by aerosols in environmental pollution and, in addition, highlights gaps in our current knowledge. Aerosol particles are ubiquitous in the Earth’s atmosphere and are central to many environmental issues; ranging from the Earth’s radiative budget to human health. Aerosol size distribution and chemical composition are crucial parameters that determine their dynamics in the atmosphere. Sources of aerosols are both anthropogenic and natural ranging from vehicular emissions to dust resuspension. Ambient concentrations of aerosols are elevated in urban areas with lower values at rural sites. A comprehensive understanding of aerosol ambient characteristics requires a combination of measurements and modeling tools. Legislation for ambient aerosols has been introduced at national and international levels aiming to protect human health and the environment.

  20. DRAGON-West Japan campaign in 2012: regional aerosol measurements over Osaka

    NASA Astrophysics Data System (ADS)

    Sano, I.; Mukai, S.; Holben, B. N.; Nakata, M.; Yonemitsu, M.; Sugimoto, N.; Fujito, T.; Hiraki, T.; Iguchi, N.; Kozai, K.; Kuji, M.; Muramatsu, K.; Okada, Y.; Okada, Y.; Sadanaga, Y.; Tohno, S.; Toyazaki, Yasuo; Yamamoto, Kouhei

    2012-11-01

    It is known that the aerosol distribution in Asia is complicated due to the increasing emissions of anthropogenic aerosols in association with economic growth and natural dust significantly varied with the seasons. Therefore it is clear that local spatially and temporally resolved measurements of atmospheric aerosols in Asian urban city are necessary. Since Osaka, Kobe, Kyoto, and Nara are located in very close each others (all cities are included in around 70×70 km2 area). The population of the region is around 13 millions including neighbor prefectures, accordingly air quality in this region is slightly bad in comparison with the remote area. Furthermore, in recent years, Asian dusts and anthropogenic small particles some times transported from China and cover these cities throughout year. DRAGON (Distributed Regional Aerosol Gridded Observation Network) is a project of dense sun/sky radiometer network in the urban area. The DRAGON-West Japan field campaign was performed over Osaka and neighbor cities with 7 AERONET instruments from March to end of May in 2012. As results, DRAGON measurements indicate small differences among the values of AOT over Osaka region.

  1. Changes in radiative forcing in Amazonia: the influence of clouds and aerosols controlling carbon budget

    NASA Astrophysics Data System (ADS)

    Artaxo, Paulo

    2016-07-01

    Surface radiation fluxes are critically important in photosynthetic processes that controls carbon assimilation and losses in tropical forests. Clouds and aerosols control the surface radiation fluxes in Amazonia, and the ratio of diffuse and direct radiation directly affects photosynthetic plant processes. Biomass burning emissions changes the atmosphere aerosol loading. The background aerosol optical thickness in wet season Amazonia is about 0.1 at 550 nm, while during the dry season AOT can reach values as high as 3-4 over large areas. The increase in diffuse radiation significantly enhance photosynthesis. Remote sensing measurements using MODIS and AERONET were used to measure the large scale aerosol distribution over Amazonia, and LBA flux towers provided the carbon balance over several sites. The enhancement in carbon uptake for AOD between 0.1 and 1 can reach 45%. For AOD above 1, the reduction in the direct flux starts to dominate and a strong reduction in carbon uptake is observed. Cloud cover also has a huge impact on carbon balance in Amazonia, but it is more difficult to quantify. These effects controls carbon balance in Amazonia.

  2. Tropical Atlantic Dust and Smoke Aerosol Variabilities Related to the Madden-Julian Oscillation in MODIS and MISR Observations

    NASA Technical Reports Server (NTRS)

    Guo, Yanjuan; Tian, Baijun; Kahn, Ralph A.; Kalashnikova, Olga; Wong, Sun; Waliser, Duane E.

    2012-01-01

    In this study, MODIS fine mode fraction and MISR non-spherical fraction are 2used to derive dust and smoke AOT components (tau(sub dust) and tau(sub smoke)) over the tropical Atlantic, and their variabilities related to the Madden-Julian Oscillation (MJO) are then investigated. Both MODIS and MISR show a very similar dust and smoke winter climatology. tau(sub dust) is found to be the dominant aerosol component over the tropical Atlantic while tau(sub smoke) is significantly smaller than tau(sub dust). The daily MODIS and MISR tau(sub dust) are overall highly correlated, with the correlation coefficients typically about 0.7 over the North Atlantic. The consistency between the MODIS and MISR dust and smoke aerosol climatology and daily variations give us confidence to use these two data sets to investigate their relative contributions to the total AOT variation associated with the MJO. However, unlike the MISR dust discrimination, which is based on particle shape retrievals, the smoke discrimination is less certain, based on assumed partitioning of maritime aerosol for both MISR and MODIS. The temporal evolution and spatial patterns of the tau(sub dust) anomalies associated with the MJO are consistent between MODIS and MISR. The tau(sub dust) anomalies are very similar to those of tau anomalies, and are of comparable magnitude. In contrast, the MJO-related tau(sub smoke) anomalies are rather small, and the tau(sub mar) anomalies are negligible. The consistency between the MODIS and MISR results suggests that dust aerosol is the dominant component on the intra-seasonal time scale over the tropical Atlantic Ocean.

  3. Aerosol distribution apparatus

    DOEpatents

    Hanson, W.D.

    An apparatus for uniformly distributing an aerosol to a plurality of filters mounted in a plenum, wherein the aerosol and air are forced through a manifold system by means of a jet pump and released into the plenum through orifices in the manifold. The apparatus allows for the simultaneous aerosol-testing of all the filters in the plenum.

  4. Solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1992-03-17

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration is disclosed. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  5. Improved solid aerosol generator

    DOEpatents

    Prescott, D.S.; Schober, R.K.; Beller, J.

    1988-07-19

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates. 2 figs.

  6. Solid aerosol generator

    DOEpatents

    Prescott, Donald S.; Schober, Robert K.; Beller, John

    1992-01-01

    An improved solid aerosol generator used to produce a gas borne stream of dry, solid particles of predetermined size and concentration. The improved solid aerosol generator nebulizes a feed solution of known concentration with a flow of preheated gas and dries the resultant wet heated aerosol in a grounded, conical heating chamber, achieving high recovery and flow rates.

  7. Tropopsheric Aerosol Chemistry via Aerosol Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Worsnop, Douglas

    2008-03-01

    A broad overview of size resolved aerosol chemistry in urban, rural and remote regions is evolving from deployment of aerosol mass spectrometers (AMS) throughout the northern hemisphere. Using thermal vaporization and electron impact ionization as universal detector of non-refractory inorganic and organic composition, the accumulation of AMS results represent a library of mass spectral signatures of aerosol chemistry. For organics in particular, mass spectral factor analysis provides a procedure for classifying (and simplifying) complex mixtures composed of the hundreds or thousands of individual compounds. Correlations with parallel gas and aerosol measurements (e.g. GC/MS, HNMR, FTIR) supply additional chemical information needed to interpret mass spectra. The challenge is to separate primary and secondary; anthropogenic, biogenic and biomass burning sources - and subsequent - transformations of aerosol chemistry and microphysics.

  8. Investigation on the structure of water/AOT/IPM/alcohols reverse micelles by conductivity, dynamic light scattering, and small angle X-ray scattering.

    PubMed

    Zhang, Xiaoguang; Chen, Yingjun; Liu, Jiexiang; Zhao, Chuanzhuang; Zhang, Haijiao

    2012-03-29

    We have systematically investigated the effect of alcohols (ethanol, propanol, butanol, and pentanol) on the structure of the water/AOT/IPM system using conductivity, dynamic light scattering (DLS), and small-angle X-ray scattering (SAXS) techniques. The results show that no percolation phenomenon is observed in the water/AOT/IPM system, whereas the addition of ethanol (propanol and butanol) induces apparently percolation. The threshold water content (W(p)) depends closely on the alcohol type and concentration. The effect of alcohols on the conductance behavior is discussed from the physical properties of alcohols, the interfacial flexibility, and the attractive interactions between droplets. The hydrodynamic diameter of droplets (d(H)) obtained from DLS increases markedly with the increase in water content (W(0)); however, it decreases gradually with increasing alcohol chain length and concentration. SAXS measurements display distinctly the shoulder, the low hump peaks, and the heavy tail phenomenon in the pair distance distribution function p(r) profile, which rely strongly on the alcohol species and its concentration. The gyration radius (R(g)) increases with increasing W(0), and decreases with the increase of alcohol chain length and concentration. Schematic diagram of the conductance mechanism of water/AOT/IPM/alcohol systems is primarily depicted. Three different phases of the discrete droplets, the oligomers, and the isolated ellipsoidal droplets existed in the different W(0) ranges correspond to three different stages in the conductivity-W(0) curve. Coupling the structure characteristics of reverse micelles obtained from DLS and SAXS techniques with conductivity could be greatly helpful to deeply understand the percolation mechanism of water/AOT/IPM/alcohols systems. PMID:22380931

  9. Long-term changes of aerosol optical and radiative properties and their role in global dimming and brightening

    NASA Astrophysics Data System (ADS)

    Hatzianastassiou, N.; Papadimas, C. D.; Matsoukas, C.; Pavlakis, K.; Fotiadi, A.; Wild, M.; Vardavas, I.

    2009-04-01

    Global dimming and brightening (GDB) have profound effects on the Earth's environment. For example, GDB counteracts or supplements greenhouse warming. Atmospheric aerosols, through their interaction with solar radiation (direct, indirect and semi-direct effects) can affect GDB. Changes in aerosol burden or other physical and optical properties can modify tendencies of GDB. For example, satellite observations of aerosol amounts, available since the early 1980s, but only over the oceans, indicate a downward trend since about 1990, consistent with the observed brightening during this period. There is a need, however, to investigate similar trends, but also over land, and to relate them with contemporary GDB. The seasonal and inter-annual variability of the natural, but also anthropogenic aerosol direct radiative effect on solar radiation at the Earth's surface (DREsurf) and the contribution of aerosols to global dimming and brightening (GDB) is estimated over the period 1984-2001. This is achieved by using a spectral radiative transfer model together with Total Ozone Mapping Spectrometer (TOMS) aerosol optical thickness (AOT) and other satellite (International Satellite Cloud Climatology Project, ISCCP-D2), NCEP/NCAR reanalysis and Global Aerosol Data Set (GADS) data for surface and atmospheric parameters. The major findings are mostly related to natural and less to anthropogenic aerosols because of limitations of the TOMS observational technique. The model results indicate that aerosols exert a strong surface cooling over the globe by reducing locally the incoming surface solar radiation by up to 70 W m-2. This direct radiative effect averaged over the globe for the period 1984-2001, is equivalent to 5 W m-2, associated with 6.5 and 3.5 W m-2, for the Northern and Southern Hemispheres, respectively. However, this aerosol DREsurf effect shows an important inter-annual variability as large as 200%. A strong solar brightening, or decreased aerosol DREsurf, by as much as

  10. Validation and divergence of the activation energy barrier crossing transition at the AOT/lecithin reverse micellar interface.

    PubMed

    Narayanan, S Shankara; Sinha, Sudarson Sekhar; Sarkar, Rupa; Pal, Samir Kumar

    2008-03-13

    In this report, the validity and divergence of the activation energy barrier crossing model for the bound to free type water transition at the interface of the AOT/lecithin mixed reverse micelle (RM) has been investigated for the first time in a wide range of temperatures by time-resolved solvation of fluorophores. Here, picosecond-resolved solvation dynamics of two fluorescent probes, ANS (1-anilino-8-naphthalenesulfonic acid, ammonium salt) and Coumarin 500 (C-500), in the mixed RM have been carefully examined at 293, 313, 328, and 343 K. Using the dynamic light scattering (DLS) technique, the size of the mixed RMs at different temperatures was found to have an insignificant change. The solvation process at the reverse micellar interface has been found to be the activation energy barrier crossing type, in which interface-bound type water molecules get converted into free type water molecules. The activation energies, Ea, calculated for ANS and C-500 are 7.4 and 3.9 kcal mol(-1), respectively, which are in good agreement with that obtained by molecular dynamics simulation studies. However, deviation from the regular Arrhenius type behavior was observed for ANS around 343 K, which has been attributed to the spatial heterogeneity of the probe environments. Time-resolved fluorescence anisotropy decay of the probes has indicated the existence of the dyes in a range of locations in RM. With the increase in temperature, the overall anisotropy decay becomes faster revealing the lability of the microenvironment at elevated temperatures. PMID:18281975

  11. A small-angle neutron scattering study of intermicellar interactions in microemulsions of AOT, water, and near-critical propane

    SciTech Connect

    Kaler, E.W. ); Billman, J.F. ); Fulton, J.L.; Smith, R.D. )

    1991-01-10

    Small-angle neutron scattering (SANS) measurements of high-pressure solutions of propane/sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/D{sub 2}O have demonstrated that a water-in-oil microemulsion phase can be formed in propane. The dispersed droplets are, within experimental error, the same size as those formed in conventional microemulsions at the same water-to-surfactant ratio, and the size does not depend on propane density. The interdroplet interaction potential was modeled as a hard-core repulsion augmented by a strong and extremely short range attraction. This model describes droplets whose hydrocarbon tails are strongly attractive to the hydrocarbon tails of adjacent droplets. The SANS fit shows that the magnitude of the tail-tail attractive interactions may be much stronger than the longer range van der Waals type attractive interactions between the water cores of the droplets. These findings confirm results of IR and UV-vis spectroscopic studies of near-critical and supercritical fluid microemulsions.

  12. Estimation of mechanical strength of unilamellar and multilamellar AOT/water vesicles and their rupture using micropipet aspiration.

    PubMed

    Sagar, G Hema; Bellare, Jayesh R

    2009-10-22

    Vesicles prepared from surfactant sodium dioctyl sulfosuccinate (AOT) were characterized by micropipet aspiration for determining membrane bending rigidity and area expansion modulus and mechanism of rupture. Unilamellar vesicles (ULV) and multilamellar vesicles (MLV) were studied. The mechanical properties calculated using micropipet aspiration for ULV were found to be 5-10 k(B)T, K(a) = 100 +/- 20 mN/m and for MLV were 8-15 k(B)T, K(a) = 120 +/- 30 mN/m. These properties fall with the range of lipid (PC) membrane measurements (values). However, the membrane rigidity of multilamellar vesicles was found to be approximately 3 times larger than that of unilamellar vesicles. The apparent area expansion moduli of multilamellar vesicles are of the order 1.4 times, sustained far greater areal strain before rupture compared to that of unilamellar vesicles. A dynamic structural change in MLV is demonstrated upon stress by micropipet aspiration. MLV at stress undergoes various stages of deformation. The fluctuation in size and shape of MLV led to separation of bilayers from the stack and decrease in vesicle diameter facilitating in formation of new equilibrium MLV, for it to sustain the specified membrane tension, a new mechanism that is demonstrated experimentally. PMID:19764699

  13. Stability and comparative analysis of AOT/water/isooctane reverse micelle system using dynamic light scattering and molecular dynamics.

    PubMed

    Vasquez, V R; Williams, B C; Graeve, O A

    2011-03-31

    We use molecular dynamics (MD) and dynamic light scattering (DLS) measurements to analyze the size of reverse micellar structures in the AOT-water-isooctane system at different water-to-surfactant ratios at ambient temperature and pressure. We find good qualitative agreement for the size and morphology behavior of the reverse micelle structures between molecular dynamics calculations and DLS measurements; however, the average values for the reverse micelle size distributions are systematically larger for the DLS measurements. The latter tends to capture the average hydrodynamic size of the structures based on self-diffusion rather than the average physical size as measured in MD simulations, explaining the systematic deviations observed. The combination of MD with DLS allows a better interpretation of the experimental results, in particular for conditions where the structures are nonspherical, commonly observed at lower water-to-surfactant ratios. We also present and analyze the effect of zirconyl chloride on the micellar size distributions in this system. These type of salts are common for reverse micellar synthesis processes. We find that zirconyl chloride affects significantly the size distributions. PMID:21384835

  14. MASTER OT J095503.19-355149.4 - a probable Dwarf Nova

    NASA Astrophysics Data System (ADS)

    Buckley, D. A. H.; Kniazev, A.; Potter, S. B.; Lipunov, V.; Tiurina, N.; Gorbovskoy, E.

    2016-02-01

    Followup optical imaging and spectroscopic observations with SALT of the optical transient MASTER OT J095503.19-355149.4, tentatively identified (ATel #8741) as the optical counterpart of the Fermi GBM trigger 478121068 (GCN #19092), were conducted on 2016-02-26.78 UT. From un-calibrated g', r' and i' exposures (30 sec each) with the SALTICAM CCD camera, the transient appeared to be approximately 1 mag brighter (V ~ 17) than the MASTER-SAAO observations of the previous night (reported in ATel #8741) and was also seen to be a relatively red object compared to other stars in the field.

  15. Complete Genome Sequence of the Larvicidal Bacterium Lysinibacillus sphaericus Strain OT4b.25

    PubMed Central

    Rey, Andrés; Silva-Quintero, Laura

    2016-01-01

    Lysinibacillus sphaericus