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Sample records for aerosol ot aot

  1. Formose reaction accelerated in aerosol-OT reverse micelles

    PubMed Central

    Masaoka, Makoto; Michitaka, Tomohiro

    2016-01-01

    The formose reaction in reverse micelles of aerosol-OT (AOT), triton X-100 (TX), and hexadecyltrimethylammonium bromide (CTAB) was investigated. Time–conversion data have indicated that the interfacial water layer of AOT reverse micelles is a medium that accelerates formation of glycolaldehyde in the formose reaction. The 13C NMR spectra for the products of the formose reaction using formaldehyde-13C as starting material are indicative of the formation of ethylene glycol as a major product. PMID:28144336

  2. Self-assembly of new surface active ionic liquids based on Aerosol-OT in aqueous media.

    PubMed

    Rao, K Srinivasa; Gehlot, Praveen Singh; Trivedi, Tushar J; Kumar, Arvind

    2014-08-15

    New anionic ionic liquid surfactants have been synthesized by replacing the sodium cation of Aerosol-OT (sodium dioctylsulfosuccinate, [Na]AOT) with various biocompatible moieties, such as 1-butyl-3-methyl imidazolium ([C4mim]), proliniumisopropylester ([ProC3]), cholinium ([Cho]), and guanidinium ([Gua]). The Aerosol-OT derived ionic liquids (AOT-ILs) were found fairly soluble in water and formed vesicles above a critical vesicle concentration (CVC) which depended upon the nature of cation, and followed the order: [ProC3]<[C4mim]<[Gua]<[Cho]AOT-ILs, a structural transformation has been observed for [C4mim]AOT above CVC, because of certain amphiphilic character in the cation [C4mim]. Thermodynamic parameters calculated from ITC and conductivity techniques revealed that the vesicle formation process is entropy driven for [C4mim]AOT, whereas the process is both enthalpy and entropy driven for other AOT-ILs. In order to check the versatility of synthesized AOT-ILs we have tested their dissolution behavior in a different class of ionic liquids. All the AOT-ILs were found fairly soluble in the hydrophilic IL, ethanolammonium formate (EOAF), whereas only [C4mim]AOT and [ProC3]AOT were found soluble in hydrophobic IL, [C4mim]Tf2N. Such combinations can have potential for construction of stable colloidal formulations or microemulsions in ionic liquid media.

  3. Enhancement of the skin permeation of clindamycin phosphate by Aerosol OT/1-butanol microemulsions.

    PubMed

    Junyaprasert, Varaporn Buraphacheep; Boonsaner, Panee; Leatwimonlak, Sujitra; Boonme, Prapaporn

    2007-08-01

    Microemulsions of water/isopropyl palmitate (IPP)/Aerosol OT (AOT)/1-butanol were developed as alternative formulations for topical delivery of clindamycin phosphate. Effect of AOT:1-butanol ratios on microemulsion region existence in the pseudoternary phase diagrams was investigated. The 2:1 AOT:1-butanol provided the largest microemulsion region. Five microemulsions of 1% w/w clindamycin phosphate were prepared and characterized. The permeation through human epidermis of the microemulsions was evaluated and compared with the 70% isopropanol solution using modified Franz diffusion cells. The drug permeation from all microemulsions was found to be significantly greater than that from the solution, indicating the enhancement of the skin permeation by the microemulsions. Within the same microemulsion type, the drug permeation increased with increasing the amount of AOT:1-butanol. The drug permeation from oil-in-water (o/w) microemulsions was relatively higher than that from water-in-oil (w/o) microemulsions. In addition, all microemulsions were stable for at least three months at 30 +/- 1 degrees C.

  4. 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.

  5. Monitoring of urban air pollution from MODIS and AERONET Aerosol Optical Thickness (AOT) data

    NASA Astrophysics Data System (ADS)

    Tijani, K.; Chiaradia, M.; Guerriero, L.; Pasquariello, G.; Morea, A.; Nutricato, R.; Preziosa, G.

    2012-12-01

    Air pollution, caused by fuel industries and urban traffic and its environmental impact, are of considerable interest to studies in air quality. In this paper, the monitoring of the air pollution over urban areas in Italy through Aerosol Optical Thickness (AOT) data retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) measurements is presented. The high spatio-temporal frequency of MODIS AOT products (twice per day at 470nm, 1km full resolution) demonstrates that this satellite can be potentially used to routinely monitor the air pollution over land, especially urban area, which is the main source of aerosol particles. In this work AOT data derived by MODIS from November 2010 to February 2011 (winter period) and from May 2011 to August 2011 (summer period) were compared with AOT measurements from 6 different Aerosol Robotic Network (AERONET) stations over Italy (Bari, Lecce, Roma, Ispra, Potenza, Etna). The statistical analysis shows a good agreement between the ground based AOT measurements and the values retrieved using space based sensors, as shown in Figure 1. For all the stations the mean error is negligible, with a correlation ranging from 0.725 (in the worst case) to 0.96 (see Table 1). Moreover, LANDSAT-panchromatic images were used to discriminate urban and rural areas, based on the typical finger-like projections of urban land uses. The results of this study will be presented and commented. Acknowledgements This work was funded by Apulian Region in the framework of the ECOURB project. (Analisi e Modelli di inquinamento atmosferico e termico per sistemi di ECOlabeling URBano, 2009-2012). Figure 1: Scatter plot between AOT derived from MODIS and AERONET for Lecce City in summer period from May 2011 to August 2011. Y = - 0.023+0.86x (fit) ; Table 1: Statistical Analysis Report on the difference between AOT derived from MODIS and AERONET from May 2011 to August 2011 (summer period) for 6 different Aerosol Robotic Network (AERONET) stations

  6. Neutron and X-Ray Reflectivity Studies of the Adsorption of Aerosol-OT at the Air-Water Interface: The Structure of the Calcium Salt

    PubMed

    Li; Lee; Thomas; Penfold

    1997-03-15

    We have used neutron and X-ray reflection to determine the structure of a layer of calcium bis-(2-ethyl 1-hexyl) sulphosuccinate (Aerosol-OT or AOT) adsorbed at the air/solution interface. The widths of the distributions of the chains and head groups of the molecule, and their positions in relation to the underlying water, have been measured at four concentrations varying from the solubility limit (CMC) at 4 x 10(-4) M to 1 x 10(-6) M. Over this concentration range the coverage changes from 68 ± 3 to 142 ± 8 Å2 per AOT unit. The structure of the layer both is quite different from that of NaAOT and varies quite differently with surface concentration. The Ca(AOT)2 layer is slightly (1 Å) further out from the water, but the chain region is thinner for the calcium surfactant. This is reflected most in the greatly reduced chain to head separation, which drops from about 6 Å in NaAOT to about 4 Å in Ca(AOT)2.

  7. 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.

  8. An enhanced VIIRS aerosol optical thickness (AOT) retrieval algorithm over land using a global surface reflectance ratio database

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

    The Visible/Infrared Imager Radiometer Suite (VIIRS) on board the Suomi National Polar-orbiting Partnership (S-NPP) satellite has been retrieving aerosol optical thickness (AOT), operationally and globally, over ocean and land since shortly after S-NPP launch in 2011. However, the current operational VIIRS AOT retrieval algorithm over land has two limitations in its assumptions for land surfaces: (1) it only retrieves AOT over the dark surfaces and (2) it assumes that the global surface reflectance ratios between VIIRS bands are constants. In this work, we develop a surface reflectance ratio database over land with a spatial resolution 0.1° × 0.1° using 2 years of VIIRS top of atmosphere reflectances. We enhance the current operational VIIRS AOT retrieval algorithm by applying the surface reflectance ratio database in the algorithm. The enhanced algorithm is able to retrieve AOT over both dark and bright surfaces. Over bright surfaces, the VIIRS AOT retrievals from the enhanced algorithm have a correlation of 0.79, mean bias of -0.008, and standard deviation (STD) of error of 0.139 when compared against the ground-based observations at the global AERONET (Aerosol Robotic Network) sites. Over dark surfaces, the VIIRS AOT retrievals using the surface reflectance ratio database improve the root-mean-square error from 0.150 to 0.123. The use of the surface reflectance ratio database also increases the data coverage of more than 20% over dark surfaces. The AOT retrievals over bright surfaces are comparable to MODIS Deep Blue AOT retrievals.

  9. 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

  10. Fluorescent behavior of B-phycoerythrin in microemulsions of aerosol OT/water/isooctane.

    PubMed

    Bermejo, Ruperto; Tobaruela, Diego J; Talavera, Eva M; Orte, Angel; Alvarez-Pez, Jose M

    2003-07-15

    Taking advantage of its unusual fluorescent properties, the incorporation of B-phycoerythrin (B-PE) in aerosol OT (AOT, sodium bis-(2-ethylhexyl) sulphosuccinate)/water/isooctane microemulsions was investigated by following their steady-state and time-resolved fluorescence as a function of the water-to-surfactant molar ratio, w(0). The fluorescent intensity at 575 nm increased continuously with increasing water content, saturating at a w(0) around 35 and staying practically constant at w(0)> or =40. The steady-state anisotropy showed an initial increase with increasing water content until w(0)=23 and then decreased strongly, staying practically constant when w(0)> or =40. The values of the fluorescent parameters, anisotropy and fluorescent intensity, were unchanged when the water content of the system increased in the range between w(0)=40 to 50. This implies the effective incorporation of B-PE in the microemulsion droplets with w(0)> or =40, as well as the equilibrium of the dispersion at these water/surfactant ratios, since higher water content does not affect the main surrounding microenvironment of the protein. The overall incorporation in the microemulsion droplets caused minor spectroscopic changes with respect to biliprotein in aqueous solution of 20 mM sodium phosphate buffer, pH 7.0, such as a blue absorption shift of 3 nm and an emission shift of 1.5 nm, as well as a slight increase in excitation anisotropy spectrum mainly caused by a decrease in protein mobility. Therefore, there are no important interactions between the chromophores and the AOT sulfonate head groups. Emission intensity decays followed complex kinetics in both aqueous and dispersion media. The stability with time and temperature of the biliprotein in the microemulsion was higher than in the aqueous solution. All the results can be explained in terms of B-PE inclusion in the water droplets of AOT microemulsions where the protein has similar configuration and conformation to that in

  11. Effects of diethylenetriamine and Aerosol OT on the stability of oil-in-water emulsion stabilized by interfacial polyurea film.

    PubMed

    Mikami, T

    1994-01-01

    The stability of oil-in-water emulsions containing a triisocyanate soluble in the oil phase and an amine in the water phase was investigated. The oil component was di-n-butyl phthalate (DBP) containing Aerosol OT as an emulsifier. The time required for the average size parameter to reach a constant value was studied. It was found that the polyurea film produced by an interfacial polymerization reaction between the amine and the triisocyanate contributed to forming a stable emulsion at a lower Aerosol OT concentration, but at a higher Aerosol OT concentration the amine did not show any effect on the emulsion stability.

  12. 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.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Characterisation of microstructures formed in isopropyl palmitate/water/Aerosol OT:1-butanol (2:1) system.

    PubMed

    Boonme, P; Krauel, K; Graf, A; Rades, T; Junyaprasert, V B

    2006-11-01

    The aim of this work was to determine the type and microstructure of microemulsion samples formed in IPP/water/AerosolOT:1-butanol (2:1) systems as a case study for the investigation of microemulsions. The concentration of the surfactant/cosurfactant mixture was kept constant while the ratio of water to oil was varied. Several techniques were used to investigate the types and phase transitions of the microemulsion formulations. The experimental methods used included visual observation cross-polarized light microscopy (PLM) appearance, conductivity, viscosity, cryo-field emission scanning electron microscopy (cryo-FESEM), differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), and fluorescence resonance energy transfer (FRET). Taken together, the results of the various techniques imply that the systems investigated are undergoing two transitions as a function of water concentration. Between 10-15%w/w of water, the systems change from headgroup hydrated surfactant solutions in oil (or possibly very small reversed micellar systems) to w/o microemulsions. These systems then change to o/w microemulsions between 25-30%w/w of water. The transitions however, appear to be gradual, as for example the DSC data indicates a transition between 15-20%w/w of water. Furthermore, for some methods the changes observed were very weak, and only with supportive data of other techniques can the phase behaviour of the microemulsion systems be interpreted with confidence. Interestingly, no indication of the presence of a bicontinuous intermediate microstructure was found. Liquid crystal formation was detected in samples containing 55%w/w of water.

  18. Reversible switching of electrical conductivity in an AOT-isooctane-water microemulsion via photoisomerization of azobenzene.

    PubMed

    Bufe, Markus; Wolff, Thomas

    2009-07-21

    The electrical conductivity of microemulsions composed of aerosol OT (AOT), isooctane, and water as a function of temperature was studied in the absence and presence of azobenzene, and consequences of an in situ trans-cis photoisomerization of azobenzene were investigated. A conductivity onset upon raising the temperature of a water-in-oil microemulsion indicates percolation. Small amounts (0.1-5% w/w) of solubilized azobenzene induce higher percolation temperatures T(p) (by up to 19 K), and photoisomerization of azobenzene shifts T(p) back to values that may be below T(p) in the absence of azobenzene. Consequently, the microemulsion can be switched from nonconducting to conducting by exposing samples to UV-light at lambda > 310 nm, without varying temperature or composition. The effect reverts within several minutes after turning off the irradiation lamp through thermal reisomerization. By that, reversible switching of electrical conductivity is brought about.

  19. 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.

  20. Switching electrical conductivity in an AOT-isooctane-water microemulsion through photodimerization of solubilized N-methyl-2-quinolone.

    PubMed

    Bufe, Markus; Wolff, Thomas

    2006-09-28

    The electrical conductivity of microemulsions composed of Aerosol OT (AOT), isooctane and water as a function of temperature was studied in the absence and presence of N-methyl-2-quinolone (NMQ), and consequences of an in situ photodimerization of NMQ were investigated. A conductivity increase upon raising the temperature of a water-in-oil microemulsion indicates percolation. Percolation temperatures (Tp) can be influenced specifically by the addition of certain substances. Small amounts of solubilized N-methyl-2-quinolone induce lower Tp (by up to 9 K), and photodimerization of NMQ shifts Tp back to higher values. Consequently, the microemulsion can be switched from conducting to non-conducting without varying temperature or composition by exposing samples to UV light at lambda > 310 nm. The effect can be reverted in part by irradiation at lambda = 250 nm. Coumarin derivatives--structurally related to NMQ--show much slighter effects.

  1. 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

  2. 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.

  3. 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.

  4. Hygroscopic growth and deliquescence of NaCl nanoparticles coated with surfactant AOT.

    PubMed

    Alshawa, Ahmad; Dopfer, Otto; Harmon, Christopher W; Nizkorodov, Sergey A; Underwood, Joelle S

    2009-07-02

    Aerosolized nanoparticles of NaCl coated with variable amounts of surfactant AOT were generated by electrospraying AOT/NaCl aqueous solutions, followed by neutralizing and drying the resulting particles. A tandem differential mobility analyzer was used to select a narrow size distribution of particles with mobility equivalent diameters below 20 nm and monitor their hygroscopic growth as a function of relative humidity. Effects of the particle size and relative amount of surfactant on the hygroscopic growth of NaCl were studied. For pure NaCl nanoparticles, the deliquescence relative humidity (DRH) increased as the particle size was decreased, in full agreement with previous measurements. Below the DRH the NaCl nanoparticles had an equivalent of one-four monolayers of water adsorbed on the surface. The addition of a sub-monolayer AOT coating reduced the DRH and suppressed the hygroscopic growth of the NaCl core. At AOT coverage levels exceeding one monolayer, a clear deliquescence transition was no longer discernible. The Zdanovskii-Stokes-Robinson (ZSR) model failed to predict the observed growth factors of mixed AOT/NaCl nanoparticles reflecting a large contribution of the interfacial interactions between NaCl and AOT to the total free energy of the particles. There were indications that AOT/NaCl nanoparticles prepared by the electrospray aerosol source were enhanced in the relative mass fraction of AOT in comparison with the solution from which they were electrosprayed.

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Kishcha, Pavel; Starobinets, Boris; Long, Charles N.; Alpert, Pinhas

    2012-12-01

    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.

  7. Joint AOT-Single Scattering Albedo Retrieval in Algorithm MAIAC

    NASA Astrophysics Data System (ADS)

    Lyapustin, A.

    2015-12-01

    Multi-Angle Implementation of Atmospheric Correction (MAIAC) is a new algorithm which uses time series analysis and processing of groups of pixels for advanced cloud detection and retrieval of aerosol and surface bidirectional reflectance properties. MAIAC C6+ re-processing of MODIS data record, scheduled to begin in November 2015, will create a suite of products MCD19. Due to high 1km resolution, MAIAC provides information about fine scale aerosol variability required in different applications such as urban air quality analysis. During the past year, we developed a new MAIAC capability to retrieve Single Scattering Albedo (SSA) from MODIS by adapting OMI heritage approach of O. Torres. We will describe MAIAC retrieval approach, AERONET AOT and SSA validation for different world biomass burning regions, and will compare MAIAC results with other sensors.

  8. Master: 2 new OT

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Lipunov, V.; Buckley, D.; Tiurina, N.; Gorbovskoy, E.; Kuznetsov, A.; Balanutsa, P.; Kornilov, V.; Gress, O.; Vladimirov, V.; Kuvshinov, D.; Tlatov, A.; Senik, V.; Dormidontov, D.; Gabovich, A.; Pogrosheva, T.

    2017-01-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 18h 58m 24.93s -69d 44m 51.3s on 2017-01-25.02720 UT. The OT unfiltered magnitude is 18.0m (mlim=19.0).

  9. 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.

  10. Fragmentation of the lamellae and fractionation of polymer coils upon mixing poly(dimethylacrylamide) with the lamellar phase of aerosol OT in water.

    PubMed

    Pacios, Isabel E; Renamayor, Carmen S; Horta, Arturo; Lindman, Björn; Thuresson, Krister

    2005-12-22

    The lamellar mesophase formed by surfactant 1,4-bis(2-ethylhexyl) sodium sulfosuccinate (AOT) in deuterated water is mixed with poly(dimethylacrylamide) (PDMAA) polymers of low molecular weight (Mn= (2-20) x 10(3)). The mixtures separate into microphases (lamellar plus isotropic polymer solution). Their microstructures are studied by microscopy, small-angle X-ray scattering (SAXS), and deuterium NMR (2H NMR). According to SAXS, the lamellar phase fractionates the molecular weight distribution of the polymer, by dissolving only chains with coil sizes smaller than the thickness of the water layers between lamellae, and keeping larger chains segregated from the lamellar phase. The fraction of polymer that is segregated from the lamellar phase grows with Mn of the polymer. In 2H NMR, there are two signals, a quadrupolar doublet (water molecules hydrating the anisotropic lamellar phase contribute to this doublet) and a singlet (water molecules in the isotropic polymer solution contribute to this singlet). These two signals are deconvoluted to analyze the phases. Mixing with the polymer produces the partial dispersion of the lamellar phase into small fragments (microcrystallites). The structure of these microcrystallites is such that they conserve the regular long period spacing of the macrophase, and are thus identified in SAXS, but they are smaller than the minimum size required to produce quadrupolar splitting (about 4 microm), and therefore, in 2H NMR, they contribute to the singlet. 2H NMR can thus not distinguish between small microcrystallites and an isotropic polymer solution segregated from the lamellar phase; instead small microcrystallites are detected as an apparent increase of the isotropic solution. The degree of dispersion produced by the polymer in the lamellar phase is correlated with the degree of segregation that the polymer suffers. Thus, much greater dispersion into microcrystallites is produced by the higher Mn polymers than by the lower Mn polymers

  11. 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.

  12. 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

  13. Volumetric properties of water/AOT/isooctane microemulsions.

    PubMed

    Du, Changfei; He, Wei; Yin, Tianxiang; Shen, Weiguo

    2014-12-23

    The densities of AOT/isooctane micelles and water/AOT/isooctane microemulsions with the molar ratios R of water to AOT being 2, 8, 10, 12, 16, 18, 20, 25, 30, and 40 were measured at 303.15 K. The apparent specific volumes of AOT and the quasi-component water/AOT at various concentrations were calculated and used to estimate the volumetric properties of AOT and water in the droplets and in the continuous oil phase, to discuss the interaction between the droplets, and to determine the critical micelle concentration and the critical microemulsion concentrations. A thermodynamic model was proposed to analysis the stability boundary of the microemulsion droplets, which confirms the maximum value of R being about 65 for the stable AOT/water/isooctane microemulsion droplets.

  14. Aerosols

    Atmospheric Science Data Center

    2013-04-17

    ... article title:  Aerosols over Central and Eastern Europe     View Larger Image ... last weeks of March 2003, widespread aerosol pollution over Europe was detected by several satellite-borne instruments. The Multi-angle ...

  15. MASTER: PSN and new OT

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Gorbovskoy, E.; Lipunov, V.; Rebolo, R.; Serra-Ricart, M.; Budnev, N.; Gress, O.; Ivanov, K.; Tiurina, N.; Kuznetsov, A.; Kornilov, V.; Vladimirov, V.; Chazov, V.; Shumkov, V.; Pogrosheva, T.; Postnikov, L.; Nikitin, V.; Kuvshinov, D.

    2017-01-01

    MASTER-Tunka auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 07h 50m 43.35s +79d 09m 16.6s on 2017-01-23.88841 UT. The OT unfiltered magnitude is 17.8m (limit 19.6m).

  16. MASTER: QSO flare and OTs

    NASA Astrophysics Data System (ADS)

    Gress, O.; Shumkov, V.; Pogrosheva, T.; Lipunov, V.; Rebolo, R.; Serra-Ricart, M.; Podesta, R.; Levato, H.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Ivanov, K.; Vladimirov, V.; Lopez, C.; Podesta, F.; Saffe, C.

    2016-10-01

    MASTER-OAFA auto-detection system (Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 01h 50m 52.97s -45d 10m 15.9s on 2016-10-06.21896 UT with unfiltered m_OT=17.4m (limit 20.6m).

  17. Temporal variability of aerosol optical thickness vertical distribution observed from CALIOP

    NASA Astrophysics Data System (ADS)

    Toth, Travis D.; Zhang, Jianglong; Campbell, James R.; Reid, Jeffrey S.; Vaughan, Mark A.

    2016-08-01

    Temporal variability in the vertical distribution of aerosol optical thickness (AOT) derived from the 0.532 µm aerosol extinction coefficient is described using Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) observations over 8.5 years (June 2006 to December 2014). Temporal variability of CALIOP column-integrated AOT is largely consistent with total column AOT trends from several passive satellite sensors, such as the Moderate Resolution Imaging Spectroradiometer, Multiangle Imaging Spectroradiometer, and the Sea-viewing Wide Field-of-view Sensor. Globally, a 0.0002 AOT per year positive trend in deseasonalized CALIOP total column AOT for daytime conditions is attributed to corresponding changes in near-surface (i.e., 0.0-0.5 km or 0.5-1.0 km above ground level (agl)) aerosol particle loading, while a -0.0006 AOT per year trend during nighttime is attributed to elevated (i.e., 1.0-2.0 km or >2.0 km agl) aerosols. Regionally, increasing daytime CALIOP AOTs are found over Southern Africa and India, mostly due to changes in aerosol loading at the 1.0-2.0 km and 0.0-0.5 km agl layers, respectively. Decreasing daytime CALIOP AOTs are observed over Northern Africa, Eastern U.S., and South America (due mostly to elevated aerosol loading), while the negative CALIOP AOT trends found over Eastern China, Europe, and Western U.S. are due mostly to aerosol layers nearer the surface. To our knowledge, this study is the first to provide both a globally comprehensive estimation of the temporal variation in aerosol vertical distribution and an insight into passive sensor column AOT trends in the vertical domain.

  18. 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.

  19. Simultaneous retrieval of aerosol optical thickness and chlorophyll concentration from multiwavelength measurement over East China Sea

    NASA Astrophysics Data System (ADS)

    Shi, Chong; Nakajima, Teruyuki; Hashimoto, Makiko

    2016-12-01

    A flexible inversion algorithm is proposed for simultaneously retrieving aerosol optical thickness (AOT) and surface chlorophyll a (Chl) concentration from multiwavelength observation over the ocean. In this algorithm, forward radiation calculation is performed by an accurate coupled atmosphere-ocean model with a comprehensive bio-optical ocean module. Then, a full-physical nonlinear optimization approximation approach is used to retrieve AOT and Chl. For AOT retrieval, a global three-dimensional spectral radiation-transport aerosol model is used as the a priori constraint to increase the retrieval accuracy of aerosol. To investigate the algorithm's availability, the retrieval experiment is conducted using simulated radiance data to demonstrate that the relative errors in simultaneously determining AOT and Chl can be mostly controlled to within 10% using multiwavelength and angle covering in and out of sunglint. Furthermore, the inversion results are assessed using the actual satellite observation data obtained from Cloud and Aerosol Imager (CAI)/Greenhouse gas Observation SATellite GOSAT and MODerate resolution Imaging Spectroradiometer (MODIS)/Aqua instruments through comparison to Aerosol Robotic Network (AERONET) aerosol and ocean color (OC) products over East China Sea. Both the retrieved AOT and Chl compare favorably to the reported AERONET values, particularly when using the CASE 2 ocean module in turbid water, even when the retrieval is performed in the presence of high aerosol loading and sunglint. Finally, the CAI and MODIS images are used to jointly retrieve the spatial distribution of AOT and Chl in comparison to the MODIS AOT and OC products.

  20. Reconciling satellite aerosol optical thickness and surface fine particle mass through aerosol liquid water

    NASA Astrophysics Data System (ADS)

    Nguyen, Thien Khoi V.; Ghate, Virendra P.; Carlton, Annmarie G.

    2016-11-01

    Summertime aerosol optical thickness (AOT) over the southeast U.S. is sharply enhanced over wintertime values. This seasonal pattern is unique and of particular interest because temperatures there have not warmed over the past 100 years. Patterns in surface fine particle mass are inconsistent with satellite reported AOT. In this work, we attempt to reconcile the spatial and temporal distribution of AOT over the U.S. with particle mass measurements at the surface by examining trends in aerosol liquid water (ALW), a particle constituent that scatters radiation and affects satellite AOT but is removed in mass measurements at routine surface monitoring sites. We employ the thermodynamic model ISORROPIAv2.1 to estimate ALW mass concentrations at Interagency Monitoring of PROtected Visual Environments sites using measured ion mass concentrations and North American Regional Reanalysis meteorological data. Excellent agreement between Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations AOT and estimated ALW provides a plausible explanation for the discrepancies in the geographical patterns of AOT and aerosol mass measurements.

  1. 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

  2. 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.

  3. Cluster analysis of the impact of air back-trajectories on aerosol optical properties at Hornsund, Spitsbergen

    NASA Astrophysics Data System (ADS)

    Rozwadowska, A.; Zieliński, T.; Petelski, T.; Sobolewski, P.

    2010-02-01

    In this paper, spectra of aerosol optical thickness from the AERONET (AErosol RObotic NETwork) station at Hornsund in the southern part of Spitsbergen were employed to study the impact of air mass history on aerosol optical thickness for wavelength λ=500 nm - AOT(500) - and the Ångström exponent. Backward trajectories computed, using the NOAA HYSPLIT model, were used to trace air history. It was found that in spring, the changes in AOT values over the Hornsund station were strongly influenced by air mass trajectories 8 days or longer in duration, arriving both in the free troposphere and at an altitude of 1 km above sea level. Nevertheless, free tropospheric advection was dominant. AOT variability in summer was best explained by the local direction and speed of advection (1-day trajectories) and was dominated by the effectiveness of cleansing processes. During the ASTAR 2007 campaign, the aerosols near Hornsund displayed low AOT values ranging from 0.06 to 0.09, which is lower than the mean AOT(500) for spring seasons from 2005 to 2007 (0.110±0.007; mean ± standard deviation of mean). 9 April 2007 with AOT(500)=0.147 was exceptional. The back-trajectories belonged to clusters with low and average cluster mean AOT. Apart from the maximum AOT of 9 April 2007, the observed AOT values were close to or lower than the means for the clusters to which they belonged.

  4. 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.

  5. 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.

  6. Uncertainty effects caused by different/limited temporal sampling and cloud occurrence in trend estimate of cloud-free AOTs retrieved from polar-orbiting satellite observations

    NASA Astrophysics Data System (ADS)

    Yoon, Jongmin; Burrows, John P.; Vountas, Marco; von Hoyningen-Huene, Wolfgang; Chang, Dong Yeong; Richter, Andreas; Hilboll, Andreas

    2014-05-01

    Long-term accumulated records of aerosol optical thickness (AOT) retrieved from several satellite observations during the past decade are enable to estimate the global and regional trends in atmospheric aerosol in many studies. However, despite significant advances in sensor calibration and retrieval accuracy, still considerable uncertainties can cause an inevitable error in the trend estimates. Most of all, the uncertainties caused by different/limited temporal sampling and cloud occurrence have hardly been discussed in previous studies. In this study, using the resampled data from real-time AERONET Level 2.0 AOTs, it is demonstrated that the limited/different temporal sampling can result in significant errors ranging from -156.3% to +399.2% between "ideal satellite-derived trend" and "actual trend". The cloud occurrence prevents to retrieve cloud-free AOT and therefore damages the statistical representativeness of monthly means. It can bring a clear spatial division or discontinuity in the trend estimates between land and surrounding ocean areas where cloud frequently occurs. This study presents a new approach to minimize the uncertainties by use of weighted least squares regression and multiple satellite-derived AOTs from the space-born instruments (MODIS-Terra, MISR-Terra, SeaWiFS- OrbView-2, and MODIS-Aqua), and thereby provides more convincing trend estimates in atmospheric aerosols. The significant decrease in the cloud-free AOT is estimated over Western Europe (i.e. by up to about -6.59±5.30% per year from 2003 to 2008). In contrast, a statistically significant increase is observed over East China (about +5.66±4.14% per year in the same period) and it can be attributed to both the increase in industrial output and the Asian desert dust.

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

    PubMed

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

    2014-07-16

    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.

  8. 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.

  9. 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.

  10. Assessing Hourly Aerosol Property Retrieval from MSG/SEVIRI Observations in the Frameworkd of Aerosol_CCi2

    NASA Astrophysics Data System (ADS)

    Luffarelli, M.; Govaerts, Y.; Damman, A.

    2016-08-01

    A new algorithm has been designed for the joint retrieval of surface reflectance and aerosol optical thickness over land and sea surfaces. This algorithm is applied on MSG/SEVIRI data for the retrieval of hourly aerosol optical thickness. This paper examines the daily and seasonal variations of the Jacobians and their impact on the AOT retrieval.

  11. 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.

  12. Merging MODIS Terra and Aqua Level 3 Aerosol Optical Thickness for Giovanni Online Data Analysis and Visualization

    NASA Astrophysics Data System (ADS)

    Zubko, V.; Leptoukh, G.; Gopalan, A.

    2007-12-01

    With a vast amount of satellite-obtained environmental data held, the Goddard Earth Sciences Data and Information Services Center (GES DISC) researches ways to combine multi-sensor data to increase their usefulness, and to integrate it in the GES DISC Interactive Online Visualization and Analysis Infrastructure (Giovanni). Here, we studied the performance of various methods for merging-interpolating the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra and Aqua Level 3 Aerosol Optical Thickness (AOT). To quickly validate the accuracy of the merger, we introduced two confidence functions, which characterize the percentage of the merged AOT pixels as a function of the relative deviation of the merged AOT from original Terra and Aqua AOTs in respect to the original AOT standard deviations or AOT means. Experiment with three different methods for pure merging (no interpolation): simple arithmetic averaging (SIM), maximum likelihood estimate (MLE), and weighting by pixel counts (WPC) demonstrated the relative proximity of the resulting AOTs produced by the three methods with the MLE (SIM) being slightly preferable when validating with respect to AOT standard deviations (AOT means). Another experiment with eight different methods of combined merger-interpolation applied to a variety of scenes with different gap patterns showed that that the absolutely best method is when the merging of Terra and Aqua AOTs is done first followed by Optimal Interpolation to fill in the gaps. The sensitivity of the results to the gap patterns and radius of influence was assessed.

  13. New Statistical Model for Variability of Aerosol Optical Thickness and its Application to Analysis of Global Satellite Datasets

    NASA Astrophysics Data System (ADS)

    Alexandrov, M. D.; Geogdzhayev, I. V.; Cairns, B.; Mishchenko, M. I.

    2013-05-01

    We present a novel statistical model AOTVM for variability of aerosol optical thickness (AOT). Mathematically this model is based on summation of multiple realizations of certain binary Markov process. It allows for construction of realistic examples of AOT time series, which have 1-point (lognormal PDF) and 2-point (structure function) statistics consistent with each other. Unlike commonly used scale-invariant (fractal) variability models having power-law structure functions, AOTVM's second order structure function converges to a constant (double of AOT's variance) at large lags (where the AOT values at different points become essentially independent from each other). This structure function has simple analytical form convenient for use in remote sensing data analysis. Aerosol variability in AOTVM is characterized by 3 parameters independent from the mean AOT. The first parameter is the ratio between AOT's standard deviation and its mean representing the relative magnitude of AOT variability. The second parameter is the characteristic size of inhomogeneity in AOT field. It quantifies the loss of dependence between AOT values at two points in space with the increase of distance between them. The third parameter is the Hurst exponent characterizing AOT's turbulent behavior at small scales. The proposed variability model was evaluated using MODIS Terra satellite AOT product (collection 5 level 2). We took one-year-long (2006) global AOT dataset (at 550 nm wavelength) and computed means, variances, and structure functions for the data from overlapping 10 by 10 degree cells (with ocean and land treated separately). This provided a set of AOT statistics on a grid with 5-degree resolution. We demonstrated that the structure functions derived from the satellite data can be closely fitted by AOTVM's analytical expressions. These fits provide global long-term datasets of the 3 model parameters described above, thus, adding to the information content of the satellite

  14. 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.

  15. Time comparison via OTS-2

    NASA Technical Reports Server (NTRS)

    Dejong, G.; Kaarls, R.; Kirchner, D.; Ressler, H.

    1982-01-01

    The time comparisons carried out via OTS-2 between the Technical University Graz (Austria) and the Van Swinden Laboratory Delft (Netherlands) are discussed. The method is based on the use of the synchronization pulse in the TV-frame of the daily evening broadcasting of a French TV-program to Northern Africa. Corrections, as a consequence of changes in the position of the satellite coordinates are applied weekly after reception of satellite coordinates. A description of the method is given as well as some of the particular techniques used in both the participating laboratories. Preliminary results are presented.

  16. 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.

  17. 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.

  18. 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

  19. Classification of Aerosol over Central Europe by Cluster Analysis of Aerosol Columnar Optical Properties and Backward Trajectory Statistics

    NASA Astrophysics Data System (ADS)

    Szkop, Artur; Pietruczuk, Aleksander; Posyniak, Michał

    2016-12-01

    A cluster analysis is applied to the Aerosol Robotic Network (AERONET) data obtained at Belsk, Poland, as well as three nearby Central European stations (Leipzig, Minsk and Moldova) for estimation of atmospheric aerosol types. Absorption Ångstrom exponent (AAE), aerosol optical thickness (AOT) and extinction Ångstrom exponent (EAE) parameters are used. Clustering in both 2D (AOT, EAE) and 3D (AOT, EAE, AAE) is investigated. A method of air mass backward trajectory analysis is then proposed, with the receptor site at Belsk, to determine possible source regions for each cluster. Four dominant aerosol source regions are identified. The biomass burning aerosol source is localized in the vicinity of Belarusian-Ukrainian border. Slovakia and northern Hungary are found to be the source of urban/industrial pollutants. Western Poland and eastern Germany are the main sources of polluted continental aerosols. The most differentiated source region of Scandinavia, Baltic Sea and Northern Atlantic, associated with lowest values of AOT, corresponds to clean continental and possibly maritime type aerosols.

  20. Does the Madden-Julian Oscillation influence aerosol variability?

    NASA Astrophysics Data System (ADS)

    Tian, Baijun; Waliser, Duane E.; Kahn, Ralph A.; Li, Qinbin; Yung, Yuk L.; Tyranowski, Tomasz; Geogdzhayev, Igor V.; Mishchenko, Michael I.; Torres, Omar; Smirnov, Alexander

    2008-06-01

    We investigate the modulation of aerosols by the Madden-Julian Oscillation (MJO) using multiple, global satellite aerosol products: 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 MJO analysis indicates that large variations in the TOMS AI and MODIS/AVHRR AOT are found 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 weak but the background aerosol level is 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 MODIS/AVHRR pattern is consistent with ground-based Aerosol Robotic Network data. These results indicate that the MJO and its associated cloudiness, rainfall, and circulation variability systematically influence the variability in remote sensing aerosol retrieval results. Several physical and retrieval algorithmic factors that may contribute to the observed aerosol-rainfall relationships are discussed. Preliminary analysis indicates that cloud contamination in the aerosol retrievals is likely to be a major contributor to the observed relationships, although we cannot exclude possible contributions from other physical mechanisms. Future research is needed to fully understand these complex aerosol-rainfall relationships.

  1. MASTER-OAFA discovery: new bright OT

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Balanutsa, P.; Pogrosheva, T.; Lipunov, V.; Podesta, R.; Levato, H.; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Kornilov, V.; Chazov, V.; Vlasenko, D.; Vladimirov, V.; Gress, O.; Ivanov, K.; Lopez, C.; Podesta, F.; Saffe, C.; Potter, S.

    2016-10-01

    MASTER-OAFA auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 18h 06m 06.62s -62d 13m 31.3s on 2016-10-19.03627 UT. The OT unfiltered (limit 19.1m).

  2. MASTER-OAFA: OT detection during inspection

    NASA Astrophysics Data System (ADS)

    Gress, O.; Lipunov, V.; Podesta, R.; Levato, H.; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Balanutsa, P.; Kornilov, V.; Chazov, V.; Gorbunov, I.; Krylov, A.; Lopez, C.; Podesta, F.; Saffe, C.; Shumkov, V.; Pogrosheva, T.

    2017-02-01

    MASTER-OAFA auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 18h 36m 27.60s -47d 35m 18.1s on 2017-02-02.36706 UT. The OT unfiltered magnitude is 16.2m (mlim=18.1m).

  3. MASTER: new OT and QSO flare

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Lipunov, V.; Buckley, D.; Budnev, N.; Gress, O.; Gorbovskoy, E.; Tiurina, N.; Vladimirov, V.; Kornilov, V.; Kuvshinov, D.; Pogrosheva, T.; Ivanov, K.

    2017-02-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 09h 45m 05.87s -65d 43m 43.3s on 2017-02-15.91771 UT. The OT unfiltered magnitude is (mlim=18.6).

  4. 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.

  5. 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.

    2014-06-01

    Over the past several years, there has been a rapid development in the number and quality of global aerosol models intended for operational forecasting use. Indeed, most centers with global numerical weather prediction (NWP) capabilities have some program for aerosol prediction. These aerosol models typically have differences in their underlying meteorology as well as aerosol sources, sinks, microphysics and transformations. However, like similar diversity in aerosol climate models, the aerosol forecast models have fairly similar overall bulk error statistics for aerosol optical thickness (AOT)-one of the few aerosol metrics that is globally available. Experience in climate and weather prediction has shown that in situations such as this where there are several independent models, a multi-model ensemble or consensus will be top performing in many key error metrics. Further, multi-model ensembles provide a highly valuable tool for forecasters attempting to predict severe aerosol events. 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, five day AOT forecasts are analyzed for December 2011 through November 2012 from four institutions: ECMWF, JMA, NASA GSFC, and NRL/FNMOC. For dust, we also include the NOAA NGAC product in our analysis. The Barcelona Supercomputing Centre (NMMC) and UK Met office dust product have also recent become available with 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 0Z for 6 hourly forecasts out to 120 h. Basing metrics on comparisons to 21 regionally

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

    DOE PAGES

    Kishcha, Pavel; Da Sliva, Arlindo; Starobinets, Boris; ...

    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

  7. 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.

  8. Aerosol Optical Thickness Derived From Atmospheric Transmittance Using Spectroradiometer Measurements

    NASA Astrophysics Data System (ADS)

    Hwee San, Hslim; Matjafri, M. Z.; Abdullah, Abdul K.; Chow Jeng, C. J.

    section The objective of this study was to test the feasibility of hand held spectroradiometer measurements for the retrieval AOT values Twenty-six stations were chosen randomly around Penang Island and the atmospheric transmittance measurements were collected using a handheld spectroradiometer The corresponding PM10 concentrations were measured using a portable DustTrak Aerosol Monitor 8520 simultaneously with the measurements of the transmittance data The AOT values were calculated using the Beer-Lambert-Bouguer law Linear relationship was found between AOT and PM10 values in this study Finally a PM10 map was created using Kriging interpolation technique The result of the study showed the potential of a spectroradiometer data for the retrieval of AOT and PM10 to provide the air pollution information

  9. 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.

  10. Comparison of POLDER Derived Aerosol Optical Thickness to Surface Monitor Fine Particle Concentration

    NASA Astrophysics Data System (ADS)

    Leon, J.; Kacenelenbogen, M.; Chiapello, I.

    2005-12-01

    The Particulate Matter (PM) mass measured at the ground level is a common way to quantify the amount of aerosol particles in the atmosphere and is used as a standard to evaluate air quality. Satellite remote sensing is well suited for a daily monitoring of the aerosol load. However, there are no straightforward relationship between aerosol optical properties derived from the satellite sensor and the PM mass at the ground. This paper is focused on the use of Polarization and Directionality of Earth's Reflectance (POLDER-2) derived aerosol optical thickness (AOT) for the monitoring of PM2.5. We present a correlation study between PM2.5 data collected in the frame of the French Environmental protection agency, aerosol optical properties derived from Sun photometer measurements, and POLDER derived-AOT over the land. POLDER AOT retrieval algorithm over the land is based on the use of the measurement of the linear polarized light in the 670 nm and 865 nm channels. We show that only the fine fraction (below 0.3 μm) of the aerosol size distribution contributes to the signal in polarization and then to the POLDER derived-AOT and then is well suited for monitoring of fine particle. The correlation between POLDER AOT and PM2.5 is significant (R between 0.6 and 0.7) over several sites. We present a tentative evaluation of Air Quality Categories from satellite data.

  11. Aerosol characterization and transport pathway using ground-based measurement and space borne remote sensing

    NASA Astrophysics Data System (ADS)

    Boyouk, Neda; Léon, Jean-François; Delbarre, Hervé

    2008-10-01

    Using two years measurements of aerosol extinction coefficient retrieval from CALIPSO as a joint NASA-CNES satellite mission along with ground-based measurements of particle mass concentration (PM2.5), we assess particulate matter air quality over different urban and periurban areas in France. In order to understanding the influence of the long range transport onto the local aerosol load we have focused on analysing of pollution event in Lille - urban area and Dunkerque - industrial area. We compared ground- based measurements with CALIPSO measurements. The CALIPSO level 2 aerosol records are more useful because the extinction coefficient is available. We use the extinction coefficient profiles which are provided by CALIPSO to depict the vertical structure of the aerosol properties. The combination of ground- based measurements of PM2.5, aerosol optical thickness (AOT's) obtained by Aeronet network data and CALIOP data enhances the possibilities of studying transport pathway of aerosol in the atmosphere and aerosol optical properties (aerosol extinction coefficient, aerosol optical depth, atmosphere transparency). The linear relationship between AOT _CALIPSO and AOT _ Aeronet network shows a slop of 0.4 in north of France. Moreover, we observed the good relationship between PM2.5 and AOT by CALIPSO profiles with a slope of 57.59 and correlation coefficient of 0.75 over France.

  12. Global analysis of the relation between aerosols and short-lived trace gases

    NASA Astrophysics Data System (ADS)

    Veefkind, J. P.; Boersma, K. F.; Wang, J.; Kurosu, T.; Krotkov, N.; Levelt, P. F.

    2010-08-01

    The spatial and temporal correlations between concurrent satellite observations of aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and tropospheric columns of nitrogen dioxide, sulfur dioxide, and formaldehyde from the Ozone Monitoring Instrument (OMI) are used to infer information on the global composition of aerosol particles. When averaging the satellite data over large regions and longer time periods, we find significant correlation between MODIS AOT and OMI trace gas columns for various regions in the world. This suggests that enhanced aerosol and trace gas concentrations originate from common sources, such as fossil fuel combustion, biomass burning, and organic compounds released from the biosphere. This leads us to propose that satellite-inferred AOT to NO2 ratios for regions with comparable photochemical regimes can be used as indicators for the relative (local) efficiency of combustion processes. Indeed, satellites observe low AOT to NO2 ratios over the eastern United States and western Europe, and high AOT to NO2 ratios over comparably industrialized regions in eastern Europe and China. Emission databases and OMI SO2 observations over these regions suggest a much stronger sulfur contribution to aerosol formation than over the well-regulated areas of the eastern United States and western Europe. Furthermore, satellite observations show AOT to NO2 ratios are a factor 100 higher over biomass burning regions than over industrialized areas, reflecting the unregulated burning practices with strong primary particle emissions in the tropics compared to the heavily controlled combustion processes in the industrialized Northern Hemisphere. Simulations with a global chemistry transport model (GEOS-Chem) capture most of these differences, providing some confidence in our understanding of aerosol sources, formation mechanisms, and sinks. Wintertime aerosol concentrations show strongest correlations with NO2 throughout

  13. Aerosol classification using airborne High Spectral Resolution Lidar measurements - methodology and examples

    NASA Astrophysics Data System (ADS)

    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.

    2011-09-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical thickness (AOT) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, and spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of AOT and inferences of aerosol types are used to apportion AOT to aerosol type; results of this analysis are shown for several experiments.

  14. 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

  15. 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.

  16. 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.

  17. MASTER: 2 OT discovered in Argentina

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Pogrosheva, T.; Lipunov, V.; Podesta, R.; Levato, H.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Vladimirov, V.; Gress, O.; Ivanov, K.; Chazov, V.; Lopez, C.; Podesta, F.; Saffe, C.

    2016-10-01

    MASTER-OAFA, located in Argentina, with auto-detection system (Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L) discovered OT source at (RA, Dec) = 03h 19m 42.92s -45d 30m 13.9s on 2016-10-27.27597 UT. The OT unfiltered magnitude is 16.9m (mlim=20.8m).

  18. Global satellite analysis of the relation between aerosols and short-lived trace gases

    NASA Astrophysics Data System (ADS)

    Veefkind, J. P.; Boersma, K. F.; Wang, J.; Kurosu, T. P.; Krotkov, N.; Chance, K.; Levelt, P. F.

    2011-02-01

    The spatial and temporal correlations between concurrent satellite observations of aerosol optical thickness (AOT) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and tropospheric columns of nitrogen dioxide (NO2), sulfur dioxide (SO2), and formaldehyde (HCHO) from the Ozone Monitoring Instrument (OMI) are used to infer information on the global composition of aerosol particles. When averaging the satellite data over large regions and longer time periods, we find significant correlation between MODIS AOT and OMI trace gas columns for various regions in the world. This shows that these enhanced aerosol and trace gas concentrations originate from common sources, such as fossil fuel combustion, biomass burning, and organic compounds released from the biosphere. This leads us to propose that satellite-inferred AOT to NO2 ratios for regions with comparable photochemical regimes can be used as indicators for the relative regional pollution control of combustion processes. Indeed, satellites observe low AOT to NO2 ratios over the eastern United States and western Europe, and high AOT to NO2 ratios over comparably industrialized regions in eastern Europe and China. Emission databases and OMI SO2 observations over these regions suggest a much stronger sulfur contribution to aerosol formation than over the well-regulated areas of the eastern United States and western Europe. Furthermore, satellite observations show AOT to NO2 ratios are a factor 100 higher over biomass burning regions than over industrialized areas, reflecting the unregulated burning practices with strong primary particle emissions in the tropics compared to the heavily controlled combustion processes in the industrialized Northern Hemisphere. Simulations with a global chemistry transport model (GEOS-Chem) capture most of these variations, although on regional scales significant differences are found. Wintertime aerosol concentrations show strongest correlations with NO2 throughout most of the

  19. Regional and local variations in atmospheric aerosols using ground-based sun photometry during Distributed Regional Aerosol Gridded Observation Networks (DRAGON) in 2012

    NASA Astrophysics Data System (ADS)

    Sano, Itaru; Mukai, Sonoyo; Nakata, Makiko; Holben, Brent N.

    2016-11-01

    Aerosol mass concentrations are affected by local emissions as well as long-range transboundary (LRT) aerosols. This work investigates regional and local variations of aerosols based on Distributed Regional Aerosol Gridded Observation Networks (DRAGON). We constructed DRAGON-Japan and DRAGON-Osaka in spring of 2012. The former network covers almost all of Japan in order to obtain aerosol information in regional scale over Japanese islands. It was determined from the DRAGON-Japan campaign that the values of aerosol optical thickness (AOT) decrease from west to east during an aerosol episode. In fact, the highest AOT was recorded at Fukue Island at the western end of the network, and the value was much higher than that of urban areas. The latter network (DRAGON-Osaka) was set as a dense instrument network in the megalopolis of Osaka, with a population of 12 million, to better understand local aerosol dynamics in urban areas. AOT was further measured with a mobile sun photometer attached to a car. This transect information showed that aerosol concentrations rapidly changed in time and space together when most of the Osaka area was covered with moderate LRT aerosols. The combined use of the dense instrument network (DRAGON-Osaka) and high-frequency measurements provides the motion of aerosol advection, which coincides with the wind vector around the layer between 700 and 850 hPa as provided by the reanalysis data of the National Centers for Environmental Prediction (NCEP).

  20. 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

  1. 12 CFR 510.5 - Release of unpublished OTS information.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... process requests for unpublished OTS information and, where appropriate, for the OTS to assert evidentiary... have been or might be released, or the testimony of other non-OTS persons, including retained experts. (ii) OTS employees will not be authorized to provide expert or opinion testimony for private...

  2. Development of algorithm for retrieving aerosols over land surfaces from NEMO-AM polarized measurements

    NASA Astrophysics Data System (ADS)

    Pandya, Mehul R.

    2016-04-01

    Atmospheric aerosols have a large effect on the Earth radiation budget through its direct and indirect effects. A systematic assessment of aerosol effects on Earth's climate requires global mapping of tropospheric aerosols through satellite remote sensing. However aerosol retrieval over land surface remains a challenging task due to bright background of the land surfaces. Polarized measurements can provide an improved aerosol sensing by providing a means of decoupling the surface and atmospheric contribution. The Indian Space Research Organisation has planned a Multi- Angle Dual-Polarization Instrument (MADPI) onboard a Nano satellite for Earth Monitoring & Observations for Aerosol Monitoring (NEMO-AM). MADPI has three spectral bands in blue, red and near infrared spectral regions with a nominal spatial resolution of 30 m from an altitude of 500 km polar orbit. A study has been taken up with the aim of development of an algorithm for retrieving aerosol optical thickness (AOT) over land surfaces from NEMO-AM polarized measurements. The study has three major components: (1) detailed theoretical modelling exercise for computing the atmospheric and surface polarized contributions, (2) modelling of total satellite-level polarized contribution, and (3) retrieval of aerosol optical thickness (AOT) by comparing the modelled and measured polarized signals. The algorithm has been developed for MADPI/NEMO-AM spectral bands and tested successfully on similar spectral bands of POLDER/PARASOL measurements to retrieve AOT over Indian landmass having diverse atmospheric conditions. POLDER-derived AOT fields were compared with MODIS-AOT products. Results showed a very good match (R2 0.69, RMSE 0.07). Initial results have provided encouraging results, however, comprehensive analysis and testing has to be carried out for establishing the proposed algorithm for retrieving AOT from NEMO-AM measurements.

  3. 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.

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

    PubMed Central

    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 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. PMID:25096216

  5. 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.

  6. Evaluation of the representativeness of ground-based visibility for analysing the spatial and temporal variability of aerosol optical thickness in China

    NASA Astrophysics Data System (ADS)

    Zhang, Zhao Yang; Wong, Man Sing; Lee, Kwon Ho

    2016-12-01

    Although visibility is a widely-used indicator to quantify the aerosol loadings, only a few studies have been analyzed the representativeness of visibility in deriving Aerosol Optical Thickness (AOT). In this paper, ground-based visibility, MODerate-resolution Imaging Spectroradiometer (MODIS) and Multi-angle Imaging SpectroRadiometer (MISR) monthly AOT products between July 2002 and December 2014 were analyzed in order to extract the dominant modes of variability using the Singular Value Decomposition (SVD) method. The method has significant merit to reduce data dimension and examine both spatial and temporal variability simultaneously. Results indicated that the satellite retrieved AOTs agreed well with ground-based visibility in terms of inter-annual variability. The correlation coefficients in the first deseasonalized mode are greater than 0.65 between visibility and satellite AOT products. However, large differences were observed in the seasonal variability between ground-based visibility and AOT. In addition, Aerosol vertical distribution from LIdar climatology of Vertical Aerosol Structure for space-based lidar simulation studies (LIVAS) and cloud data from ground-based meteorological station were used to investigate the seasonal variability disagreement. The AOT values derived from LIVAS extinction coefficients between 0 and 500 m above surface have a stronger relationship with visibility, than total column AOT with visibility. It also indicates that seasonal variation of aerosol vertical distribution is the main cause of the disagreement between two parameters, and the uncertainties of satellite products also contribute to the disagreement. Results in this study highlighted that the visibility observation could only be used to depict the inter-annual AOT and more ancillary information could be used for studying seasonal AOT variation.

  7. 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

  8. Remote sensing of aerosols over snow using infrared AATSR observations

    NASA Astrophysics Data System (ADS)

    Istomina, L. G.; von Hoyningen-Huene, W.; Kokhanovsky, A. A.; Schultz, E.; Burrows, J. P.

    2011-06-01

    Infrared (IR) retrievals of aerosol optical thickness (AOT) are challenging because of the low reflectance of aerosol layer at longer wavelengths. In this paper we present a closer analysis of this problem, performed with radiative transfer (RT) simulations for coarse and accumulation mode of four main aerosol components. It shows the strong angular dependence of aerosol IR reflectance at low solar elevations resulting from the significant asymmetry of aerosol phase function at these wavelengths. This results in detectable values of aerosol IR reflectance at certain non-nadir observation angles providing the advantage of multiangle remote sensing instruments for a retrieval of AOT at longer wavelengths. Such retrievals can be of importance e.g. in case of a very strong effect of the surface on the top of atmosphere (TOA) reflectance in the visible spectral range. In the current work, a new method to retrieve AOT of the coarse and accumulation mode particles over snow has been developed using the measurements of Advanced Along Track Scanning Radiometer (AATSR) on board the ENVISAT satellite. The algorithm uses AATSR channel at 3.7 μm and utilizes its dual-viewing observation technique, implying the forward view with an observation zenith angle of around 55 degrees and the nadir view. It includes cloud/snow discrimination, extraction of the atmospheric reflectance out of measured brightness temperature (BT) at 3.7 μm, and interpolation of look-up tables (LUTs) for a given aerosol reflectance. The algorithm uses LUTs, separately simulated with RT forward calculations. The resulting AOT at 500 nm is estimated from the value at 3.7 μm using a fixed Angström parameter. The presented method has been validated against ground-based Aerosol Robotic Network (AERONET) data for 4 high Arctic stations and shows good agreement. A case study has been performed at W-Greenland on 5 July 2008. The day before was characterized by a noticeable dust event. The retrieved AOT maps of

  9. 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.

  10. 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

  11. 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

  12. 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

  13. 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.

  14. MASTER: OT detection during Fermi trigger inspection

    NASA Astrophysics Data System (ADS)

    Popova, E.; Lipunov, V.; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Chazov, V.; Vlasenko, D.; Vladimirov, V.; Gress, O.; Ivanov, K.; Potter, S.; Gabovich, A.

    2016-11-01

    During inspection of Fermi trigger 501261070 ( (Ra,Dec)=47.190,-47.210; GRB_ERROR_radius=3.27deg, GRB_TIME=2016/11/19 15:11:06.40UT http://gcn.gsfc.nasa.gov/other/501261070.fermi ) MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 03h 22m 52.70s -48d 29m 10.9s on 2016-11-19 21:17:17.878UT with unfiltered m_OT=17.8 (mlim=19.7).

  15. 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.

  16. 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

  17. 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

  18. Aerosolized oxytocin increases cerebrospinal fluid oxytocin in rhesus macaques.

    PubMed

    Modi, Meera E; Connor-Stroud, Fawn; Landgraf, Rainer; Young, Larry J; Parr, Lisa A

    2014-07-01

    Intranasal (IN) administration is a widely used method for examining the effect of oxytocin (OT) on social behavior and cognition in healthy subjects and psychiatric populations. IN-OT in humans enhances trust, emotional perception, and empathetic behavior and is under investigation as a potential pharmacotherapy to enhance social functioning in a variety of neuropsychiatric disorders, including autism spectrum disorders (ASD). Nonhuman primates (NHP) are an important model for understanding the effect of OT on social cognition, its neural mechanisms, and the development of IN-OT as a pharmacotherapy for treating social deficits in humans. However, NHP and even some human populations, such as very young infants and children, cannot easily follow the detailed self-administration protocol used in the majority of human IN-OT studies. Therefore, we evaluated the efficacy of several OT-administration routes for elevating central OT concentrations in rhesus macaques. First, we examined the effect of IN and intravenous (IV) routes of OT administration on concentrations of OT and vasopressin (AVP) in plasma and lumbar CSF. Second, we examined these same measures in monkeys after an aerosolized (AE) OT delivery route. All three administration routes significantly increased plasma OT concentrations, but only the AE-OT route significantly increased concentrations of CSF OT. No route affected concentrations of AVP in plasma or CSF. This study confirms that the AE route is the most effective method for increasing central OT concentrations in monkeys, and may also be an effective route, alternative to IN, for administering OT to some human populations.

  19. Trehalose-6-Phosphate-Mediated Toxicity Determines Essentiality of OtsB2 in Mycobacterium tuberculosis In Vitro and in Mice

    PubMed Central

    Koliwer-Brandl, Hendrik; Hartman, Travis; Jacobs, William R.; Ioerger, Thomas R.; Ehrt, Sabine

    2016-01-01

    Trehalose biosynthesis is considered an attractive target for the development of antimicrobials against fungal, helminthic and bacterial pathogens including Mycobacterium tuberculosis. The most common biosynthetic route involves trehalose-6-phosphate (T6P) synthase OtsA and T6P phosphatase OtsB that generate trehalose from ADP/UDP-glucose and glucose-6-phosphate. In order to assess the drug target potential of T6P phosphatase, we generated a conditional mutant of M. tuberculosis allowing the regulated gene silencing of the T6P phosphatase gene otsB2. We found that otsB2 is essential for growth of M. tuberculosis in vitro as well as for the acute infection phase in mice following aerosol infection. By contrast, otsB2 is not essential for the chronic infection phase in mice, highlighting the substantial remodelling of trehalose metabolism during infection by M. tuberculosis. Blocking OtsB2 resulted in the accumulation of its substrate T6P, which appears to be toxic, leading to the self-poisoning of cells. Accordingly, blocking T6P production in a ΔotsA mutant abrogated otsB2 essentiality. T6P accumulation elicited a global upregulation of more than 800 genes, which might result from an increase in RNA stability implied by the enhanced neutralization of toxins exhibiting ribonuclease activity. Surprisingly, overlap with the stress response caused by the accumulation of another toxic sugar phosphate molecule, maltose-1-phosphate, was minimal. A genome-wide screen for synthetic lethal interactions with otsA identified numerous genes, revealing additional potential drug targets synergistic with OtsB2 suitable for combination therapies that would minimize the emergence of resistance to OtsB2 inhibitors. PMID:27936238

  20. Competitive surfactant adsorption of AOT and Tween 20 on gold measured using a quartz crystal microbalance with dissipation.

    PubMed

    Thavorn, Jakkrit; Hamon, Joshua J; Kitiyanan, Boonyarach; Striolo, Alberto; Grady, Brian P

    2014-09-23

    Competitive surfactant adsorption of anionic surfactant AOT and nonionic surfactant Tween 20 on gold was investigated by using a quartz crystal microbalance with dissipation (QCM-D) at 25 °C. The adsorption isotherm of pure AOT did not reach a plateau at the CMC, but rather adsorption continued to increase gradually at concentrations higher than the CMC before reaching a plateau. This behavior is evidence of competitive adsorption between AOT and impurities. The adsorbed layer of AOT on gold became more viscoelastic as the concentration of AOT increased. Tween 20 reached the plateau adsorption on gold before its concentration reached the CMC, suggesting that the attraction between Tween 20 and gold is very strong. The Tween 20 adsorbed layer was rigid when compared to the AOT adsorbed layer, as indicated by low dissipation. The addition of Tween 20 to a surface covered by AOT resulted in an increase in adsorbed mass, suggestive of the insertion of Tween 20 into the AOT adsorbed layer as expected because Tween 20 is able to separate the repulsive headgroups of AOT. When AOT was added to a preformed Tween 20 layer, a drop in the adsorbed amount was found between 0 and 0.1 CMC, and then no change was observed until the CMC of AOT was reached; the adsorbed amount then increased, reaching a final adsorption greater than that of pure AOT. All data support the formation of mixed surfactant layers on the surface. Although a two-step model fit both AOT and Tween 20 adsorption kinetic data well, AOT was found to adsorb much more slowly than Tween 20.

  1. 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.

  2. 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.

  3. 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.

  4. CNEOST OT PTSS-17dmk, discovery - new OT, no VIZIER data

    NASA Astrophysics Data System (ADS)

    Li, Bin; Zhao, Haibin; Wang, Xiaofeng; Li, Wenxiong; Xu, Zhijian; Tan, Hanjie; Wang, Lifan; Zhang, Jujia

    2017-03-01

    PTSS (Purple Mountain Observtory(PMO) & Tsinghua Supernova Survey ) discovered OT source PTSS-17jdx at (RA, Dec) = 13h20m53.59s -04d14m04.70s on 2017-02-07.727524 UT with the 1.04/1.8 Schmidt Telescope( named Chinese Near Earth Object Survey Telescope , CNEOST ) at Xuyi station of PMO. The OT PTSS-17jdx SDSS-r magnitude is 17.5m.

  5. [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

  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. 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.

  8. 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.

  9. Using the Relationship between MODIS Aerosol Optical Thickness and OMI Trace Gas Columns to better understand Aerosol Formation and Chemical Composition

    NASA Astrophysics Data System (ADS)

    Veefkind, Pepijn; Boersma, Folkert; Wang, Jun; Levelt, Pieternel

    2010-05-01

    Aerosols are one of the leading uncertainties in global and regional climate change. One of the most important reasons for the limited understanding of the effects of aerosols is their strong temporal and spatial variability in chemical composition and size distribution. Important anthropogenic sources for aerosols are transportation, power plants, industries and biomass burning. Natural sources include windblown desert dust, sea spray, biogenic emissions, volcanoes, and biomass burning. Together, these sources form a complex chemical mixture of desert dust, sea salt, sulfates, nitrates and organic material. To better understand the Earth's climate system, accurate knowledge is needed on the complex relation between the emissions of precursor gases and primary aerosol particles, and aerosol composition. Satellite measurements have the horizontal and temporal coverage to assess the global effect of aerosols on climate. In addition to the information on aerosols, tropospheric columns of nitrogen dioxide (NO2), formaldehyde (HCHO) and sulfur dioxide (SO2) can be observed from space. In this contribution, the spatial and temporal correlations between AOT and tropospheric columns of NO2, SO2 and HCHO are used to derive information on the composition of the aerosols particles. Spatial correlation between AOT and NO2 indicate that the aerosols are from combustion processes, such as fossil fuel and biomass burning. The AOT to NO2 ratio provides zeroth order information on the combustion sources. This ratio is low for regions dominated by controlled fossil fuel combustion and high for biomass burning regions, whereas the difference of this ratio between these regions can be more than two orders of magnitude. Overall the GEOS-CHEM simulations can reproduce the observed AOT-NO2 ratios well. Spatial correlation between AOT and NO2 is found for many of the industrialized ad biomass burning regions in the world. Correlations with HCHO are especially important in biomass burning

  10. Aerosol fluxes in the marine boundary layer

    NASA Astrophysics Data System (ADS)

    Petelski, Tomasz; Zieliński, Tymon; Makuch, Przemysław; Kowalczyk, Jakub; Ponczkowska, Agnieszka; Drozdowska, Violetta; Piskozub, Jacek

    2010-05-01

    We present aerosol emission fluxes and concentrations calculated from in-situ measurement in the Nordic Sea from R/V Oceania. We compare vertical fluxes calculated with the eddy correlation and gradient methods. We use the results to test the hypothesis that marine aerosol emitted from the sea surface helps to clear the boundary layer from other aerosol particles. As the emitted droplets do not dry out in the highly humid surface layer air and because of their sizes most of them are deposited quickly at the sea surface. Therefore marine aerosol has many features of rain meaning that the deposition in the marine boundary layer in high wind events is controlled not only by the "dry" processes but also by the "wet" scavenging. We have estimated the effectiveness of the process using our own measurements of vertical aerosol fluxes in the Nordic Seas. This process could explain observed phenomenon of lower Arctic aerosol optical thickness (AOT) when the air masses moved over open sea than over sea-ice. We show a negative correlation between the sea-ice coverage in the seas adjacent to Svalbard and monthly AOT values in Ny Alesund.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Aerosol Classification using Airborne High Spectral Resolution Lidar Measurements

    NASA Astrophysics Data System (ADS)

    Burton, S. P.; Ferrare, R. A.; Hostetler, C. A.; Hair, J. W.; Obland, M. D.; Rogers, R.; Butler, C. F.; Cook, A.; Harper, D.; Froyd, K. D.

    2011-12-01

    The NASA Langley Research Center (LaRC) airborne High Spectral Resolution Lidar (HSRL) on the NASA B200 aircraft has acquired extensive datasets of aerosol extinction (532 nm), aerosol optical thickness (AOT) (532 nm), backscatter (532 and 1064 nm), and depolarization (532 and 1064 nm) profiles during 18 field missions that have been conducted over North America since 2006. The lidar measurements of aerosol intensive parameters (lidar ratio, depolarization, backscatter color ratio, spectral depolarization ratio) are shown to vary with location and aerosol type. A methodology based on observations of known aerosol types is used to qualitatively classify the extensive set of HSRL aerosol measurements into eight separate types. Several examples are presented showing how the aerosol intensive parameters vary with aerosol type and how these aerosols are classified according to this new methodology. The HSRL-based classification reveals vertical variability of aerosol types during the NASA ARCTAS field experiment conducted over Alaska and northwest Canada during 2008. In two examples derived from flights conducted during ARCTAS, the HSRL classification of biomass burning smoke is shown to be consistent with aerosol types derived from coincident airborne in situ measurements of particle size and composition. The HSRL retrievals of aerosol optical thickness and inferences of aerosol types are used to apportion aerosol optical thickness to aerosol type; results of this analysis are shown for several experiments.

  17. 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.

  18. 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.

  19. CNEOST OT PTSS-17dmk, discovery - new OT, no VIZIER data

    NASA Astrophysics Data System (ADS)

    Li, Bin; Zhao, Haibin; Wang, Lifan; Xu, Zhijian; Li, Wenxiong; Wang, Xiaofeng; Tan, Hanjie; Rui, Liming; Yang, Zesheng

    2017-02-01

    PTSS (Purple Mountain Observtory(PMO) & Tsinghua Supernova Survey ) discovered OT source at (RA, Dec) = 05h 28m 21.88s +59d 38m 39.26s on 2017-02-09.557376 UT with the 1.04/1.8 Schmidt Telescope( named Chinese Near Earth Object Survey Telescope , CNEOST http://www.cneost.org ) at Xuyi station of PMO. The OT (PTSS-17dmk) SDSS-r magnitude is 17.2m (limit 18.7m).

  20. Trend analysis of 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.

    2012-06-01

    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) level 2.0 spectral observations. Additionally, temporal trends of coarse- and fine-mode dominant AOTs (CdAOT and FdAOT) 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 (σt) and (2) number of observations per month (nt). Temporal increase of FdAOTs (440 nm) prevails over newly industrializing countries in East Asia (weighted trends; +6.23% yr-1 at Beijing) and active agricultural burning regions in South Africa (+1.89% yr-1 at Mongu). On the other hand, insignificant or negative trends for FdAOTs are detected over Western Europe (+0.25% yr-1 at Avignon and -2.29% yr-1 at Ispra) and North America (-0.52% yr-1 for GSFC and -0.01% yr-1 at MD_Science_Center). Over desert regions, both increase and decrease of CdAOTs (+3.37% yr-1 at Solar_Village and -1.18% yr-1 at Ouagadougou) are observed depending on meteorological conditions.

  1. Satellite remote sensing of Asian aerosols: a case study of clean, polluted and dust storm days

    NASA Astrophysics Data System (ADS)

    Lee, K. H.; Kim, Y. J.

    2010-06-01

    Satellite-based aerosol observation is a useful tool for the estimation of microphysical and optical characteristics of aerosol during more than three decades. Until now, a lot of satellite remote sensing techniques have been developed for aerosol detection. In East Asian region, the role of satellite observation is quite important because aerosols originating from natural and man-made pollution in this region have been recognized as an important source for regional and global scale air pollution. However, it is still difficult to retrieve aerosol over land because of the complexity of the surface reflection and complex aerosol composition, in particular, aerosol absorption. In this study, aerosol retrievals using Look-up Table (LUT) based method was applied to MODerate Resolution Imaging Spectroradiometer (MODIS) Level 1 (L1) calibrated reflectance data to retrieve aerosol optical thickness (AOT) over East Asia. Three case studies show how the methodology works to identify those differences to obtain a better AOT retrieval. The comparison between the MODIS and Aerosol Robotic Network (AERONET) shows better results when the suggested methodology using the cluster based LUTs is applied (linear slope=0.94, R=0.92) than when operational MODIS aerosol products are used (linear slope=0.78, R=0.87). In conclusion, the suggested methodology is shown to work well with aerosol models acquired by statistical clustering the observation data in East Asia.

  2. 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.

  3. 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.

  4. 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.

  5. A computational component analysis of dielectric relaxation and THz spectra of water/AOT reverse micelles with different water loading

    NASA Astrophysics Data System (ADS)

    Schmollngruber, Michael; Braun, Daniel; Steinhauser, Othmar

    2016-12-01

    In this computational study, we present molecular dynamics simulations of water/aerosol-OT/isooctane reverse micelles with different water loading. We compare these systems in terms of a detailed analysis of dielectric relaxation spectra and water librations in the THz region. The spectra are decomposed into contributions by molecular species and contributions from individual water solvation shells. Additionally, micellar tumbling motion is shown to have a profound influence on the observed dielectric relaxation spectra, if relaxation by internal reorganization and micellar tumbling occurs within similar time scales. A formalism to directly quantify the effect of micellar tumbling motion on a recorded dielectric spectrum is developed. Since micellar rotational diffusion obeys the laws of hydrodynamics, this method is applicable in an experimental context as well, only knowing the viscosity of the outside medium and the average volume of the reverse micelle.

  6. 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.

  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. Seasonal variations of aerosol over Dona Paula, a coastal site on the west coast of India

    NASA Astrophysics Data System (ADS)

    Suresh, T.; Desa, Elgar

    We report here the observations of the aerosol studies carried-out for three years (2000-2002) at Dona-Paula, Goa (15.456°N, 73.801°E), a coastal site on the west coast of India. Aerosol optical depths were measured using a five channel sunphotometer with wavelengths at 440, 500, 675, 870 and 936 nm. The site enjoys a tropical climate and is under the influence of the strong southwest or summer monsoon and weak northeast or winter monsoon. Being a coastal station land-sea breeze play an important role in the variations of the aerosol loading over the site and their transport to the Arabian Sea. The mean aerosol optical thicknesses (AOT) at 500 and 870 nm are 0.46 (±0.15) and 0.23 (±0.097), respectively, while the Angstrom exponent is 1.31 (±0.347). The aerosol properties over the site showed a distinct seasonal variations, with high values of AOT observed during summer, with mean values of 0.48 (±0.15) and 0.26 (±0.09) at 500 and 870 nm, respectively, while during the winter relatively low values were observed, with mean value of 0.41 (±0.14) and 0.19 (±0.09) at 500 and 870 nm, respectively. The values of Angstrom exponents observed at the site suggest that the aerosol comprise mostly of the small size particles, with relatively larger particles being observed during summer than winter. An anti-correlation is observed between the inter-annual variations in the aerosol loading and the rainfall over Goa. Aerosol properties show diurnal variations, with comparatively lower values of AOT being observed in the evening. These diurnal variations are within a limit of 10% of the average values observed for the day. Seasonal patterns in the diurnal variations of aerosol optical depths have been observed. Considering the effect of the meteorological parameters over the aerosol, it is observed that the AOT is positively correlated with water vapor column, however the wind is found to aid in the reduction of aerosol load over Goa. It can be inferred from the weak

  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. Satellite remote sensing of Asian aerosols: a case study of clean, polluted, and Asian dust storm days

    NASA Astrophysics Data System (ADS)

    Lee, K. H.; Kim, Y. J.

    2010-12-01

    In East Asia, satellite observation is important because aerosols from natural and anthropogenic sources have been recognized as a major source of regional and global air pollution. However, retrieving aerosols properties from satellite observations over land can be difficult because of the surface reflection, complex aerosol composition, and aerosol absorption. In this study, a new aerosol retrieval method called as the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite aerosol retrieval (MSTAR) was developed and applied to three different aerosol event cases over East Asia. MSTAR uses a separation technique that can distinguish aerosol reflectance from top-of-atmosphere (TOA) reflectance. The aerosol optical thickness (AOT) was determined by comparing this aerosol reflectance with pre-calculated values. Three case studies show how the methodology identifies discrepancies between measured and calculated values to retrieve more accurate AOT. The comparison between MODIS and the Aerosol Robotic Network (AERONET) showed improvement using the suggested methodology with the cluster-based look-up-tables (LUTs) (linear slope = 0.94, R = 0.92) than using operational MODIS collection 5 aerosol products (linear slope = 0.78, R = 0.87). In conclusion, the suggested methodology is shown to work well with aerosol models acquired by statistical clustering of the observation data in East Asia.

  11. Proton transport and the water environment in nafion fuel cell membranes and AOT reverse micelles.

    PubMed

    Spry, D B; Goun, A; Glusac, K; Moilanen, David E; Fayer, M D

    2007-07-04

    The properties of confined water and diffusive proton-transfer kinetics in the nanoscopic water channels of Nafion fuel cell membranes at various hydration levels are compared to water in a series of well-characterized AOT reverse micelles with known water nanopool sizes using the photoacid pyranine as a molecular probe. The side chains of Nafion are terminated by sulfonate groups with sodium counterions that are arrayed along the water channels. AOT has sulfonate head groups with sodium counterions that form the interface with the reverse micelle's water nanopool. The extent of excited-state deprotonation is observed by steady-state fluorescence measurements. Proton-transfer kinetics and orientational relaxation are measured by time-dependent fluorescence using time-correlated single photon counting. The time dependence of deprotonation is related to diffusive proton transport away from the photoacid. The fluorescence reflecting the long time scale proton transport has an approximately t-0.8 power law decay in contrast to bulk water, which has a t-3/2 power law. For a given hydration level of Nafion, the excited-state proton transfer and the orientational relaxation are similar to those observed for a related size AOT water nanopool. The effective size of the Nafion water channels at various hydration levels are estimated by the known size of the AOT reverse micelles that display the corresponding proton-transfer kinetics and orientational relaxation.

  12. Influence of anionic surfactants on the electric percolation of AOT/isooctane/water microemulsions.

    PubMed

    García-Río, L; Mejuto, J C; Pérez-Lorenzo, M; Rodríguez-Alvarez, A; Rodríguez-Dafonte, P

    2005-07-05

    A study was carried out concerning the influence of sodium alkyl sulfonates on the electric percolation of AOT/isooctane/water microemulsions ([AOT] = 0.5 M and W = [H2O]/[AOT] = 22.2). An important effect was observed with regard to the percolation temperature caused by the addition of small quantities of alkyl sulfonates (rho = [alkyl sulfonate]/[AOT] = 0.01). The short chain alkyl sulfonates (C3-C5) cause an increase in the percolation temperature, which in turn is reduced as we increase the chain length of the additive until we obtain a percolation temperature which is lower than that which is observed in the absence of an additive (C6-C8). For hydrocarbon chains of a greater length we can observe a new increase in the percolation temperature (C10-C18). This behavior has been explained as a consequence of (i) the incorporation of the additives at the interphase of the microemulsion and (ii) the geometric parameters of the different surfactants added to the microemulsion.

  13. 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.

  14. 12 CFR 510.5 - Release of unpublished OTS information.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... information also includes information that current and former employees, officers, and agents obtained in... a current or former employee, officer, or agent of the OTS (or the Federal Home Loan Bank Board, the... requests that current or former OTS employees be authorized to give testimony. (i) The request...

  15. 12 CFR 510.5 - Release of unpublished OTS information.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... information also includes information that current and former employees, officers, and agents obtained in... a current or former employee, officer, or agent of the OTS (or the Federal Home Loan Bank Board, the... requests that current or former OTS employees be authorized to give testimony. (i) The request...

  16. MASTER-OAFA, MASTER-SAAO discovery: bright OTs

    NASA Astrophysics Data System (ADS)

    Pogrosheva, T.; Shumkov, V.; Popova, E.; Lipunov, V.; Podesta, R.; Levato, H.; Buckley, D.; Lopez, C.; Podesta, F.; Saffe, C.; Potter, S.; Gorbovskoy, E.; Balanutsa, P.; Tiurina, N.; Kuznetsov, A.; Kornilov, V.; Vladimirov, V.; Gress, O.; Chazov, V.; Ivanov, K.

    2016-11-01

    MASTER-OAFA (located in Argentina) auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 20h 26m 36.17s -44d 07m 22.7s on 2016-11-29.04023 UT. The OT unfiltered magnitude is (mlim=18.6m).

  17. Fast bright OT in PGC2697102 discovered by MASTER

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Lipunov, V.; Tlatov, A.; Gorbovskoy, E.; Chazov, V.; Tiurina, N.; Kuznetsov, A.; Balanutsa, P.; Kornilov, V.; Vladimirov, V.; Gress, O.; Ivanov, K.; Kuvshinov, D.; Senik, V.; Dormidontov, D.; Parkhomenko, A.; Gabovich, A.

    2016-11-01

    MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 16h 15m 32.60s +67d 14m 45.8s on 2016-11-10.73375 UT. The OT unfiltered magnitude is (mlim=18.7m).

  18. Master-Saao Psn in PGC152788 and OT

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Gress, O.; Lipunov, V.; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Kornilov, V.; Vladimirov, V.; Chazov, V.; Kuvshinov, D.; Pogrosheva, T.; Shumkov, V.

    2017-02-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 08h 32m 56.92s -03d 51m 28.1s on 2017-02-11 22:13:06.767UT . The OT unfiltered magnitude is (mlim=19.8).

  19. MASTER-SAAO: OT detected during Fermi 508270281 inspection

    NASA Astrophysics Data System (ADS)

    Pogrosheva, T.; Balanutsa, P.; Lipunov, V.; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Gress, O.; Shumkov, V.; Kuznetsov, A.; Kornilov, V.; Chazov, V.; Potter, S.

    2017-02-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 11h 34m 18.80s -51d 33m 13.5s on 2017-02-08.93060 UT. The OT unfiltered magnitude is (mlim=18.4).

  20. 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...

  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... Minority Depository Institutions Advisory Committee will renew for a two-year period beginning August 2...), and with the approval of the Secretary of the Treasury to announce the renewal of the OTS...

  2. 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

  3. 76 FR 7630 - Open Meeting of the OTS Minority Depository Institutions Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-10

    ... Office of Thrift Supervision Open Meeting of the OTS Minority Depository Institutions Advisory Committee... OTS Minority Depository Institutions Advisory Committee (MDIAC) will convene a meeting on Tuesday..., the Office of Thrift Supervision is announcing that the OTS Minority Depository Institutions...

  4. 75 FR 13344 - Open Meeting of the OTS Minority Depository Institutions Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-19

    ... Office of Thrift Supervision Open Meeting of the OTS Minority Depository Institutions Advisory Committee... OTS Minority Depository Institutions Advisory Committee (MDIAC) will convene a meeting on Wednesday... Supervision is announcing that the OTS Minority Depository Institutions Advisory Committee will convene...

  5. Characterization of aerosol pollution events in France using ground-based and POLDER-2 satellite data

    NASA Astrophysics Data System (ADS)

    Kacenelenbogen, M.; Léon, J.-F.; Chiapello, I.; Tanré, D.

    2006-10-01

    We analyze the relationship between daily fine particle mass concentration (PM2.5) and columnar aerosol optical thickness derived from the Polarization and Directionality of Earth's Reflectances (POLDER) satellite sensor. The study is focused over France during the POLDER-2 lifetime between April and October 2003. We have first compared the POLDER derived aerosol optical thickness (AOT) with integrated volume size distribution derived from ground-based Sun Photometer observations. The good correlation (R=0.72) with sub-micron volume fraction indicates that POLDER derived AOT is sensitive to the fine aerosol mass concentration. Considering 1974 match-up data points over 28 fine particle monitoring sites, the POLDER-2 derived AOT is fairly well correlated with collocated PM2.5 measurements, with a correlation coefficient of 0.55. The correlation coefficient reaches a maximum of 0.80 for particular sites. We have analyzed the probability to find an appropriate air quality category (AQC) as defined by U.S. Environmental Protection Agency (EPA) from POLDER-2 AOT measurements. The probability can be up to 88.8% (±3.7%) for the "Good" AQC and 89.1% (±3.6%) for the "Moderate" AQC.

  6. Characterization of aerosol pollution events in France using ground-based and POLDER-2 satellite data

    NASA Astrophysics Data System (ADS)

    Kacenelenbogen, M.; Léon, J.-F.; Chiapello, I.; Tanré, D.

    2006-07-01

    We analyze the relationship between daily fine particle mass concentration (PM2.5) and columnar aerosol optical thickness derived from the Polarization and Directionality of Earth's Reflectances (POLDER) satellite sensor. The study is focused over France during the POLDER-2 lifetime between April and October 2003. We have first compared the POLDER derived aerosol optical thickness (AOT) with integrated volume size distribution derived from ground-based Sun Photometer observations. The good correlation (R=0.72) with sub-micron volume fraction indicates that POLDER derived AOT is sensitive to the fine aerosol mass concentration. Considering 1974 match-up data points over 28 fine particle monitoring sites, the POLDER-2 derived AOT is fairly well correlated with collocated PM2.5 measurements, with a correlation coefficient of 0.55. The correlation coefficient reaches a maximum of 0.80 for particular sites. We have analyzed the probability to find an appropriate air quality category (AQC) as defined by the U.S. Environmental Protection Agency (EPA) from POLDER-2 AOT measurements. The probability can be up to 88.8% (±3.7%) for the "Good'' AQC and 89.1% (±3.6%) for the "Moderate'' AQC.

  7. 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

  8. 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

  9. 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.

  10. 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.

  11. Evaluations of cirrus contamination and screening in ground aerosol observations using collocated lidar systems

    NASA Astrophysics Data System (ADS)

    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.; Liu, Zhaoyan; Liu, Gin-Rong; Campbell, James R.; Liew, Soo Chin; Barnes, John E.

    2012-08-01

    Cirrus clouds, particularly subvisual high thin cirrus with low optical thickness, are difficult to screen 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 systematically examine the susceptibility of operational aerosol products to cirrus contamination. Quality assured aerosol optical thickness (AOT) measurements were also tested against the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) vertical feature mask (VFM) and the Moderate Resolution Imaging Spectroradiometer (MODIS) thin cirrus screening parameters for the purpose of evaluating 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) estimates 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. Interface of AOT/Brij mixed reverse micellar systems: conductometric and spectrophotometric investigations.

    PubMed

    Chatterjee, Sujan; Mitra, Rajib Kumar; Paul, Bidyut Kumar; Bhattacharya, Subhash Chandra

    2006-06-15

    Solubilization and conductivity studies are carried out with AOT/Brijs (Brij-30, Brij-35, Brij-52, Brij-56, Brij-58, Brij-72, Brij-76, Brij-78)/isooctane/water mixed reverse micellar systems. Replacement of AOT molecules with large head group Brij molecules (Brij-30, Brij-35, Brij-56, Brij-58, Brij-76, Brij-78) decreases the solubilization capacity, whereas those with smaller polar head groups (Brij-52 and Brij-72) increases it. The former blends assist the conductance percolation whereas the latter retard it. An attempt has been taken to obtain more insight on the interfacial composition of the mixed interface with the help of spectrophotometric studies using 7-hydroxycoumarin as the fluorophore. The results obtained from the solubilization and conductometric studies have been correlated with those obtained from the spectroscopic studies.

  13. 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.

  14. 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

  15. 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.

  16. 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.

  17. 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.

  18. MASTER-IAC: very bright high amplitude OT

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 03h 02m 05.67s +25d 48m 34.3s on 2016-12-04.96045 UT. The OT unfiltered magnitude is 13.7m (m_limit=20.3m).

  19. 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).

  20. 2 new OT, discovered by MASTER-OAFA (Argentina)

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Lipunov, V.; Podesta, R.; Levato, H.; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Vladimirov, V.; Balanutsa, P.; Kornilov, V.; Gress, O.; Chazov, V.; Kuvshinov, D.; Lopez, C.; Podesta, F.; Saffe, C.; Gabovich, A.

    2016-11-01

    MASTER-OAFA (located in Argentina) auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 09h 23m 26.72s -76d 28m 17.7s on 2016-11-13 06:19:38UT The OT magnitude in unfiltered is (mlim=18.0m).

  1. 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

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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)...

  10. 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

  11. 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.

  12. A New, Physically Based Algorithm, for Retrieving Aerosol Properties over Land from MODIS

    NASA Astrophysics Data System (ADS)

    Levy, R. C.; Remer, L. A.; Kaufman, Y. J.; Mattoo, S.; Dickerson, R. R.

    2004-12-01

    The MODerate Imaging Spectrometer (MODIS) has been successfully retrieving aerosol properties, beginning in early 2000 from Terra and from mid 2002 from Aqua. Over land, the retrieval algorithm makes use of three MODIS channels, in the blue, red and infrared wavelengths. As part of the validation exercises, retrieved spectral aerosol optical thickness (AOT) has been compared via scatterplots against spectral AOT measured by the global Aerosol Robotic NETwork (AERONET). On one hand, global and long term validation looks promising, with two-thirds (average plus and minus one standard deviation) of all points falling between published expected error bars. On the other hand, regression of these points shows a positive y-offset and a slope less than 1.0. For individual regions, such as along the U.S. East Coast, the offset and slope are even worse. Here, we introduce an overhaul of the algorithm for retrieving aerosol properties over land, to include more physical, less empirical assumptions. The new algorithm will include surface type information, instead of assuming globally fixed ratios of visible to infrared surface reflectance. It will include updated aerosol optical properties to reflect the growing aerosol retrieved from eight-plus years of AERONET operation. The effects of polarization will be including during lookup table creation, using vector RT calculations. Most importantly, the new algorithm does not assume that aerosol is transparent in the infrared channel. This new formulation will invert reflectance observed in the three channels (blue, red, and infrared), rather than performing iterative single channel retrievals.

  13. 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.

  14. 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

  15. 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.

  16. Thermostability of Cromobacterium viscosum lipase in AOT/isooctane reverse micelle.

    PubMed

    Talukder, M M R; Zaman, M M; Hayashi, Y; Wu, J C; Kawanishi, T

    2007-04-01

    The thermostability of Cromobacterium viscosum lipase (EC 3.1.1.3) entrapped in AOT (sodium bis-[2-ethylhexyl] sulfosuccinate) reverse micelles was increased by the addition of short-chain polyethylene glycol (PEG 400). Two different approaches were considered: (1) the determination of half-life time and (2) the mechanistic analysis of deactivation kinetics. The half-life of lipase entrapped in AOT/isooctane reverse micelles with PEG 400 at 60 degrees C was 28 h, ninefold higher than that in reverse micelles without PEG 400. The lipase entrapped in both reverse micellar systems followed a series-type deactivation mechanism involving two first-order steps. The deactivation constant for the first step at 60 degrees C in PEG containing reverse micelles was 0.055 h!1, 11-fold lower than that in reverse micelles without PEG, whereas it remained almost constant for the second step. The inactivation energy of the lipase entrapped in reverse micelles with and without PEG 400 was 88.12 and 21.97 kJ/mol, respectively.

  17. 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.

  18. 12 CFR 510.5 - Release of unpublished OTS information.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Section 510.5 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY MISCELLANEOUS... with the OTS's performance of its responsibilities, such as records concerning supervision, regulation... authority having general supervision of such state-chartered savings associations. (iv) Reports...

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Mapping of PM10 surface concentrations derived from satellite observations of aerosol optical thickness over South-Eastern France

    NASA Astrophysics Data System (ADS)

    Péré, J.-C.; Pont, V.; Mallet, M.; Bessagnet, B.

    2009-01-01

    This work aims at developing a methodology based on in-situ experimental observations in order to use satellite retrievals as a tool for monitoring air particulate pollution. This methodology is applied during summer time on the South-Eastern France, which is one of the most polluted zones over Europe, enclosing further large cities and industrial sites. In a first time, we consider correlations between daily mean AERONET AOT and PM10 concentrations at five sites located as well close to as far from pollution sources. Our results show significant correlation coefficients, ranging from 0.68 to 0.79, following the site studied. Several factors like aerosol vertical distribution or hygroscopic growth factor could affect the link between PM10 ground measurements and aerosol optical thickness. To statistically strengthen this approach, we gather data sets from three types of sites (urban, near urban and rural) and establish a linear relationship between daily mean AOT measured from AERONET and PM10 mass concentrations. Secondly and thanks to good agreements between AOT measured from AERONET and AOT retrieved from the MODIS sensor, we calculate estimated concentrations of PM10 by using MODIS retrievals above the South-Eastern France. Uncertainties about this approach are discussed.

  4. 75 FR 24775 - Open Meeting of the OTS Mutual Savings Association Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-05-05

    ... interested in listening to the meeting and members of the public who require auxiliary aid should e-mail OTS... the MSAAC by any one of the following methods: E-mail address: mutualcommittee@ots.treas.gov ; or...

  5. Software OT&E Guidelines. Volume 1. Software Test Manager’s Handbook

    DTIC Science & Technology

    1981-02-01

    CLASSIFICATION OF THIS PAGE( W ~h Data Xntetd) Blk 20 cont’d. (AFTECP 800-4); 5. Software Support Facility Evaluation Tools User’s Handbook (AFTECP 800...description of the AFTEC approach to OT&E of software. The document is not directive, but rather a reference document for planning OT&E. It contains...Critical Design Review (CDR) ........... .... 39 M. AFTEC Produced Publications ............... ... 40 1. OT&E Approach . ..... .......... 41 2. OT&E

  6. 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.

  7. 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.

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

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 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...

  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. 75 FR 63895 - Open Meeting of the OTS Minority Depository Institutions Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-18

    ... Office of Thrift Supervision Open Meeting of the OTS Minority Depository Institutions Advisory Committee... OTS Minority Depository Institutions Advisory Committee (MDIAC) will convene a meeting on Wednesday.... SUPPLEMENTARY INFORMATION: By this notice, the Office of Thrift Supervision is announcing that the OTS...

  12. Aerosol Particle Property Comparisons Between MISR and AERONET Retrieved Values

    NASA Astrophysics Data System (ADS)

    Gaitley, B. J.; Kahn, R. A.

    2005-12-01

    Aerosol optical depth (AOT) data from the Multi-angle ImagingSpectroRadiometer (MISR) instrument aboard the NASA Earth Observing System's Terra satellite have already been systematically compared with ground-based data from the AERONET network. As a result of that study, MISR data are now being reprocessed with improved aerosol algorithms and aerosol models. The follow-on study reported here systematically compares MISR and AERONET particle micro-physical properties. This project is currently underway. Our goal is to use the statistical power of numerous AERONET measurements to map the behavior of the MISR property retrievals, identify strength and surprises in the MISR data, and use this information both to refine further the MISR retrieval algorithms and to assess the likely error envelopes in the MISR products. Multi-year data from 36 carefully chosen sites having good long-term measurement records are stratified by broad classes of aerosol air mass types: maritime, biomass burning, desert dust, pollution, and continental aerosols. Available AERONET spectral AOT measurements for two-hour windows around MISR overpass times are interpolated to MISR wavelengths and averaged, and AOT variability over the two-hour window is noted. Sky-scan AERONET data, taken only once an hour, are also were interpolated to MISR wavelengths, and are averaged over a four-hour window provided the variability is smaller than MISR sensitivity to particle properties based on previous work. MISR retrievals over the 17.6 km standard retrieval regions that include the AERONET sites are preferentially used for the comparison. The MISR measurements are averages of over all "successful" aerosol type models in the MISR algorithm climatology, where success is measured by the degree to which multi-angle, multi-spectral top-of-atmosphere radiances match modeled radiances, using several chi-squared tests. Angstrom exponent, single scattering albedo, and size distribution mean values and variance

  13. Estimation of the aerosol radiative forcing at ground level, over land, and in cloudless atmosphere, from METEOSAT-7 observation: method and first results

    NASA Astrophysics Data System (ADS)

    Elias, T.; Roujean, J.-L.

    2007-09-01

    A new method is proposed to estimate the spatial and temporal variability of the solar radiative flux reaching the surface (DSSF) over land, as well as the Aerosol Radiative Forcing (ARF), in cloud-free atmosphere. The objective of global applications of the method is fulfilled by using the visible broadband of METEOSAT-7 satellite which scans Europe and Africa on a half-hourly basis. The method relies on a selection of best correspondence between METEOSAT-7 radiance and DSSF computed with a radiative transfer code. The validation of DSSF is performed comparing retrievals with ground-based measurements acquired in two contrasted environments, i.e. an urban site near Paris and a continental background site in South East of France. The study is concentrated on aerosol episodes occurring around the 2003 summer heat wave, providing 42 cases of comparison for variable solar zenith angle (from 59° to 69°), variable aerosol type (biomass burning emissions and urban pollution), and variable aerosol optical thickness (a factor 6). The method reproduces measurements of DSSF within an accuracy assessment of 20 Wm-2 (5% in relative) in 70% of the cases, and within 40 Wm-2 in 90% of the cases. Considering aerosol is the main contributor in changing the measured radiance at the top of the atmosphere, DSSF temporal variability is assumed to be caused only by aerosols, and consequently the ARF at ground level and over land is also retrieved: ARF is computed as the difference between DSSF and a parameterised aerosol-free reference level. Retrievals are linearly correlated with the ground-based measurements of the aerosol optical thickness (AOT): sensitivity is included between 120 and 160 Wm-2 per unity of AOT at 440 nm. AOT being an instantaneous measure indicative of the aerosol columnar amount, we therefore prove the feasibility to infer instantaneous aerosol radiative impact at the ground level over land with METEOSAT-7 visible channel.

  14. Estimation of the aerosol radiative forcing at ground level, over land, and in cloudless atmosphere, from METEOSAT-7 observation: method and case study

    NASA Astrophysics Data System (ADS)

    Elias, T.; Roujean, J.-L.

    2008-02-01

    A new method is proposed to estimate the spatial and temporal variability of the solar radiative flux reaching the surface over land (DSSF), as well as the Aerosol Radiative Forcing (ARF), in cloud-free atmosphere. The objective of regional applications of the method is attainable by using the visible broadband of METEOSAT-7 satellite instrument which scans Europe and Africa on a half-hourly basis. The method relies on a selection of best correspondence between METEOSAT-7 radiance and radiative transfer computations. The validation of DSSF is performed comparing retrievals with ground-based measurements acquired in two contrasted environments: an urban site near Paris and a continental background site located South East of France. The study is concentrated on aerosol episodes occurring around the 2003 summer heat wave, providing 42 cases of comparison for variable solar zenith angle (from 59° to 69°), variable aerosol type (biomass burning emissions and urban pollution), and variable aerosol optical thickness (a factor 6 in magnitude). The method reproduces measurements of DSSF within an accuracy assessment of 20 W m-2 (5% in relative) in 70% of the situations, and within 40 W m-2 in 90% of the situations, for the two case studies considered here. Considering aerosol is the main contributor in changing the measured radiance at the top of the atmosphere, DSSF temporal variability is assumed to be caused only by aerosols, and consequently ARF at ground level and over land is also retrieved: ARF is computed as the difference between DSSF and a parameterised aerosol-free reference level. Retrievals are linearly correlated with the ground-based measurements of the aerosol optical thickness (AOT): sensitivity is included between 120 and 160 W m-2 per unity of AOT at 440 nm. AOT being an instantaneous measure indicative of the aerosol columnar amount, we prove the feasibility to infer instantaneous aerosol radiative impact at the ground level over land with METEOSAT-7

  15. 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

  16. Characterization of patatin esterase activity in AOT-isooctane reverse micelles.

    PubMed

    Jiménez, M; Escribano, J; Gandía-Herrero, F; Chazarra, S; Cabanes, J; García-Carmona, F; Pérez-Gilabert, M

    2002-01-01

    Patatin is a family of glycoproteins that accounts for 30-40% of the total soluble protein in potato (Solanum tuberosum L.) tubers. This protein has been reported not only to serve as a storage protein but also to exhibit lipid acyl hydrolase (LAH) activity. In this study patatin is characterized in AOT-isooctane reverse micelles. The influence on the enzymatic activity of characteristic parameters of reverse micelles, w(o) (= H(2)O/AOT), and the percentage of H(2)O, theta, were investigated. The results obtained show that patatin esterase activity varies with w(o) but remains constant throughout the range of theta values studied. The variation with w(o) showed that the activity follows an S-shaped behavior pattern, reaching a maximum at about w(o) = 20 for 2% H(2)O. Patatin esterase activity was compared with p-nitrophenyl (PNP) fatty acid esters of different chain lengths. The activity was much higher for PNP-caprylate. The pH optimum was 6.0, different from the value obtained when patatin esterase activity was measured in mixed micelle systems. The optimal temperature was 35 degrees C, above which the activity decreased to almost zero. The kinetic parameters were also evaluated (K(m) = 10 mM, V(m) = 158 microM/min, V(m)/K(m) = 15.8 x 10(-3) min(-1)). This paper shows the suitability of reverse micelles for measuring patatin esterase activity, since it allows the study of the enzyme in similar conditions to that prevailing in vivo.

  17. 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.

  18. 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.

  19. MASTER OT J125532.84-050442.8 is Himalia

    NASA Astrophysics Data System (ADS)

    Denisenko, D.

    2016-11-01

    Bright optical transient MASTER OT J125532.84-050442.8 reported by Shumkov et al., ATel #9766 is the satellite of Jupiter Himalia. Here is the ephemeris of Jupiter VI for observatory code [Z22] around the reported time of observations by MASTER-IAC (2016-11-17.26843 UT = 06:26:32 UT) generated using MPC Natural Satellites Ephemeris Service: Date UT R.A. (J2000) Decl.

  20. 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.

  1. 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.

  2. 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.

  3. Near-cloud aerosol properties from the 1 km resolution MODIS ocean product

    NASA Astrophysics Data System (ADS)

    Várnai, Tamás.; Marshak, Alexander

    2014-02-01

    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 550 nm AOT changes instantaneous direct aerosol radiative forcing by up to 8 W/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.

  4. Direct radiative forcing of aerosols in cloudy condition using CALIPSO satellite data

    NASA Astrophysics Data System (ADS)

    Oikawa, E.; Nakajima, T.; Winker, D. M.

    2013-12-01

    The aerosol direct effect occurs by direct scattering and absorption of solar and thermal radiation. Shortwave direct aerosol radiative forcing (DARF) under clear-sky condition is estimated about 5 Wm-2 from satellite retrievals and model simulations [Yu et al., 2006ACP]. Simultaneous observations of aerosols and clouds are very limited, thus it is difficult to validate the estimation of DARF under cloudy-sky condition. In 2006, the CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations) satellite was launched with the space-borne lidar, CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization). This enabled us to get data of the vertical distribution of aerosols and clouds all over the world. Oikawa et al. [2013JGR] estimated DARF under clear-sky, cloudy-sky, and all-sky conditions using CALIPSO and MODIS (Moderate resolution Imaging Spectrometer) data. Over Atlantic Ocean off southwest Africa, biomass burning aerosols are transported above low-level clouds and cause large positive DARF [Oikawa et al., 2013JGR; Chand et al., 2009Nat. Geosci.; De Graaf et al., 2012JGR; Takemura et al., 2005JGR]. We calculate DARF using CALIOP Level 2 Cloud and Aerosol Layer Products Version 3 and the method of Oikawa et al. [2013]. In this study, we focus on the case that aerosols exist above clouds (above-cloud case) in 2007. Over Atlantic Ocean off southwest Africa, DARF caused by smoke aerosols is +7.1 Wm-2 in September. On the other hand, aerosol optical thickness (AOT) of smoke is small as close to 0 Wm-2 in spring season. Over North Pacific, yellow sand and industrial smoke are transported from Asia and DARF is +5.2 Wm-2 in May. Dust AOT at 532 nm is 0.014 and polluted dust AOT at 532 nm is 0.052; in other words, a large part of dust emitted from Taklamakan and Gobi deserts are mixed with the industrial smoke and transported to the Pacific Ocean according to the CALIPSO algorithms.

  5. 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.

  6. Physicochemical investigations of microemulsification of eucalyptus oil and water using mixed surfactants (AOT+Brij-35) and butanol.

    PubMed

    Mitra, Rajib K; Paul, Bidyut K

    2005-03-15

    Microemulsification of a vegetable oil (eucalyptus) with single and mixed surfactants (AOT and Brij-35), cosurfactant of different lipophilicities (isomers of butanol), and water were studied at different surfactant and cosurfactant mixing ratios. The phase diagrams of the quaternary systems were constructed using unfolded and folded tetrahedron, wherein the phase characteristics of different ternary systems can be underlined. The microemulsion zone was found to be dependent upon the mixing ratios of surfactant and cosurfactant; the largest microemulsion zone was formed with 1:1 (w/w) S:CS. The effects of temperature and additives (NaCl, urea, glucose, and bile salts of different concentrations) on the phase behavior were examined. The mixed microemulsion system showed temperature insensitivity, whereas the Brij-35 (single) stabilized system exhibited a smaller microemulsion zone at elevated temperature. NaCl and glucose increased the microemulsion zone up to a certain concentration, beyond which the microemulsion zones were decreased. These additives decreased the microemulsion zones as temperature was increased. The effect of urea on microemulsion zone was found to be insignificant even at the concentration 3.0 mol dm(-3). Little effect on microemulsion zone was shown by NaC (sodium cholate) at 0.25 and 0.5 mol dm(-3) at different temperatures. The conductance of the single (AOT) and mixed microemulsion system (AOT+Brij-35) depends upon the water content and mixing ratios of the surfactants, and a steep rise in conductance was observed at equal weight percentages of oil and water. Viscosities for both single (AOT) and mixed (AOT+Brij-35) surfactant systems passed through maxima at equal oil and water regions showing structural transition. The viscosities for microemulsion systems increased with increasing Brij-35 content in the AOT+Brij-35 blend. Conductances and viscosities of different monophasic compositions in the absence and presence of additives (NaCl and

  7. 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

  8. 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.

  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. 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.

  11. 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.

  12. alpha-lactalbumin-AOT charge interactions tune phase structures in isooctane/brine mixtures.

    PubMed

    Kim, Jun Y; Dungan, Stephanie R

    2009-07-21

    Self-assembly of the anionic surfactant AOT with the protein alpha-lactalbumin in isooctane/brine mixtures results in phase structures whose type, size, and shape differ considerably from those formed by the surfactant alone. Small-angle X-ray scattering was used to determine the size and shape of these structures for 5.4 < pH < 11.2 and 0.25, 0.33, and 0.4 wt % NaCl. All pH values were above the reported isoelectric point for the protein. The composition of the system (except for salt) was fixed, with 2.5 wt % surfactant in equivolume mixtures of oil and water and either 0 or 0.4 wt % protein. Under these conditions, AOT in the absence of protein always formed spherical, water-in-oil (w/o) microemulsion droplets in the organic phase with no self-assembly in the aqueous phase. In the presence of alpha-lactalbumin, self-assembled structures were formed in both aqueous and organic phases, and the size and shape of these was tuned by both pH and [NaCl]. Protein-surfactant interaction was weakest at the most alkaline pH, with protein-free, spherical droplets forming in the organic phase and surfactant-decorated soluble protein clusters forming in the aqueous phase. As pH was decreased, protein increasingly partitioned to the organic phase and droplets became ellipsoidal and much larger in volume, with these effects enhanced at lower salt concentration. Aqueous structures were also strongly affected by pH, shifting from prolate protein/surfactant aggregates at alkaline pH to oil-in-water, oblate microemulsion droplets at neutral pH. At acidic pH and higher salt concentration, self-assembly shifted toward a third, anisotropic aqueous phase, which contained discoid bilayer structures. It is proposed that hydrophobic attraction causes association of the protein with the surfactant monolayer, and pH and [salt] tune the system via the protein by modifying electrostatic repulsion and monolayer curvature.

  13. The impact of air mass advection on aerosol optical properties over Gotland (Baltic Sea)

    NASA Astrophysics Data System (ADS)

    Zdun, Agnieszka; Rozwadowska, Anna; Kratzer, Susanne

    2016-12-01

    In the present paper, measurements of aerosol optical properties from the Gotland station of the AERONET network, combined with a two-stage cluster analysis of back trajectories of air masses moving over Gotland, were used to identify the main paths of air mass advection to the Baltic Sea and to relate them to aerosol optical properties, i.e. the aerosol optical thickness at the wavelength λ = 500 nm, AOT (500) and the Ångström exponent for the spectral range from 440 to 870 nm, α(440,870). One- to six-day long back trajectories ending at 300, 500 and 3000 m above the station were computed using the HYSPLIT model. The study shows that in the Gotland region, variability in aerosol optical thickness AOT(500) is more strongly related to advections in the boundary layer than to those in the free troposphere. The observed variability in AOT(500) was best explained by the advection speeds and directions given by clustering of 4-day backward trajectories of air arriving in the boundary layer at 500 m above the station. 17 clusters of 4-day trajectories arriving at altitude 500 m above the Gotland station (sea level) derived using two-stage cluster analysis differ from each other with respect to trajectory length, the speed of air mass movement and the direction of advection. They also show different cluster means of AOT(500) and α(440,870). The cluster mean AOT(500) ranges from 0.342 ± 0.012 for the continental clusters M2 (east-southeast advection with moderate speed) and 0.294 ± 0.025 for S5 (slow south-southeast advection) to 0.064 ± 0.002 and 0.069 ± 0.002 for the respective marine clusters L3 (fast west-northwest advection) and M3 (north-northwest advection with moderate speed). The cluster mean α(440,870) varies from 1.65-1.70 for the short-trajectory clusters to 0.98 ± 0.03 and 1.06 ± 0.03 for the Arctic marine cluster L4 (fast inflow from the north) and marine cluster L5 (fast inflow from the west) respectively.

  14. 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.

  15. 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

  16. Local viscosity and solvent relaxation experienced by rod-like fluorophores in AOT/4-chlorophenol/m-xylene organogels

    NASA Astrophysics Data System (ADS)

    Dandapat, Manika; Mandal, Debabrata

    2017-01-01

    Organogels prepared from AOT/4-chlorophenol/m-xylene are immobile in the macroscopic sense, with a well-characterized internal structure. However, the molecular level dynamics inside the gels is not too clear, although a very slow structural relaxation has been reported previously. Using a set of rod-like fluorophores, we find that the rotational mobility of a small guest molecule inside the gel can be extremely fast, indicating presence of sufficiently low-microviscosity domains. These domains consist of m-xylene solvent molecules trapped in the interstices of fiber bundles comprising columnar stacks of 4-chlorophenol surrounded by AOT molecules. However, interstitial trapping of m-xylene does retard its own dynamics, which explains the slow solvent relaxation inside the gels. Hence, the state of m-xylene in the organogel may be characterized as "bound", in contrast to the "free" state in neat m-xylene.

  17. Fluorescent Probe Study of AOT Vesicle Membranes and Their Alteration upon Addition of Aniline or the Aniline Dimer p-Aminodiphenylamine (PADPA).

    PubMed

    Iwasaki, Fumihiko; Luginbühl, Sandra; Suga, Keishi; Walde, Peter; Umakoshi, Hiroshi

    2017-02-28

    Artificial vesicles formed from sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in aqueous solution are used successfully as additives for enzymatic oligomerizations or polymerizations of aniline or the aniline dimer p-aminodiphenylamine (PADPA) under slightly acidic conditions (e.g., pH 4.3 with horseradish peroxidase and hydrogen peroxide as oxidants). In these systems, the reactions occur membrane surface-confined. Therefore, (i) the physicochemical properties of the vesicle membrane and (ii) the interaction of aniline or PADPA with the AOT membrane play crucial roles in the progress and final outcome of the reactions. For this reason, the properties of AOT vesicles with and without added aniline or PADPA were investigated by using two fluorescent membrane probes: 1,6-diphenyl-1,3,5-hexatriene (DPH) and 6-lauroyl-2-dimethylaminonaphthalene (Laurdan). DPH and Laurdan were used as "sensors" of the membrane fluidity, surface polarity, and membrane phase state. Moreover, the effect of hexanol, alone or in combination with aniline or PADPA, as a possible modifier of the AOT membrane, was also studied with the aim of evaluating whether the membrane fluidity and surface polarity is altered significantly by hexanol, which, in turn, may have an influence on the mentioned types of reactions. The data obtained indicate that the AOT vesicle membrane at room temperature and pH 4.3 (0.1 M NaH2PO4) is more fluid and has a more polar surface than in the case of fluid phospholipid vesicle membranes formed from 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). Furthermore, the fluorescence measurements indicate that mixed AOT-hexanol membranes are less fluid than pure AOT membranes and that they have a lower surface polarity than pure AOT membranes. PADPA strongly binds to AOT and to mixed AOT/hexanol membranes and leads to drastic changes in the membrane properties (decrease in fluidity and surface polarity), resulting in Laurdan fluorescence spectra, which are characteristic for

  18. Fast aerosol optical thickness retrieval from MERIS data with the use of fast radiative transfer code and analytical radiative transfer solutions

    NASA Astrophysics Data System (ADS)

    Kokhanovsky, Alexander; Katsev, Iosif; Prikhach, Alexander; Zege, Eleonora

    We present the new fast aerosol retrieval technique (FAR) to retrieve the aerosol optical thick-ness (AOT), Angstrom parameter, and land reflectance from spectral satellite data. The most important difference of the proposed techniques from NASA/MODIS, ESA/MERIS and some other well-known AOT retrieval codes is that our retrievals do not use the look-up tables (LUT) technique but instead it is based on our previously developed extremely fast code RAY for ra-diative transfer (RT) computations and includes analytical solutions of radiative transfer. The previous version of the retrieval code (ART) was completely based at the RT computations. The FAR technique is about 100 times faster than ART because of the use combination of the RAY computation and analytical solution of the radiative transfer theory. The accuracy of these approximate solutions is thoroughly checked. Using the RT computations in the course of the AOT retrieval allows one to include any available local models of molecular atmosphere and of aerosol in upper and middle atmosphere layers for the treated area. Any set of wave-lengths from any satellite optical instruments can be processed. Moreover, we use the method of least squares in the retrieval of optical parameters of aerosol because the RAY code pro-vides the derivatives of the radiation characteristics with respect to the parameters in question. This technique allows the optimal use on multi-spectral information. The retrieval methods are flexible and can be used in synergetic algorithms, which couple data of two or more satel-lite receivers. These features may be considered as definite merits in comparison with the LUT technique. The successful comparison of FAR retrieved data with results of some other algorithms and with AERONET measurements will be demonstrated. Beside two important problems, namely, the effect of a priory choice of aerosol model to the retrieved AOT accuracy and effect of adjacent pixels containing clouds or snow spots is

  19. 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.

  20. 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.

  1. The effect of water on the microstructure and properties of benzene/[bmim][AOT]/[bmim][BF4] microemulsions.

    PubMed

    Bai, Tingting; Ge, Rile; Gao, Yanan; Chai, Jinling; Slattery, John M

    2013-11-28

    In the present contribution, results concerning the role of small amounts of water in the 1-butyl-3-methylimidazolium bis 2-ethylhexyl sulfosuccinate ([bmim][AOT]) based 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4])-in-benzene reverse microemulsions are emphasized. The microemulsion aggregates have demonstrated features in common with traditional aqueous systems, such as a normal microemulsion droplet size and decreased stability due to the addition of a polar component. Dynamic light scattering (DLS) showed that the size change of microemulsion with added water depends on the loaded [bmim][BF4] content in the microemulsion: when the [bmim][BF4] content is low, the microemulsion diameter first decreases and then increases, while the size remains about the same for microemulsions with a moderate [bmim][BF4] loading and a successive increase in size was found for high-loaded [bmim][BF4] microemulsions. (1)H NMR along with two-dimensional rotating frame nuclear Overhauser effect (NOE) experiments (ROESY) revealed that water molecules formed wide interactions with both 1-butyl-3-methylimidazolium ([bmim]) and bis 2-ethylhexyl sulfosuccinate ([AOT]), leading to a decrease in the headgroup area of [bmim][AOT], i.e. α value, which will decrease the microemulsion size. On the other hand, addition of water can simultaneously swell the microemulsions, causing an increase in the diameter. It is also deduced that the Coulomb forces between the [AOT] and [bmim] should be one of the main driving forces for the formation of [bmim][BF4]-in-benzene microemulsions.

  2. Effect of added alpha-lactalbumin protein on the phase behavior of AOT-brine-isooctane systems.

    PubMed

    Rohloff, Catherine M; Shimek, Justin W; Dungan, Stephanie R

    2003-05-15

    We have found that the presence of <1 wt% of the globular protein alpha-lactalbumin has a significant impact on the equilibrium phase behavior of dilute sodium bis(ethylhexyl) sulfosuccinate (AOT)/brine/isooctane systems. Nuclear magnetic resonance (NMR), Karl Fischer titration, and ultraviolet spectroscopy were used to determine the surfactant, oil, water, and protein content of the organic and aqueous phases as a function of the total surfactant and protein present. As a small amount of alpha-lactalbumin is added to the mixture, there is a substantial increase (up to 80%) in the maximum water solubility in the water-in-oil microemulsion phase. Dynamic light scattering measurements indicate that this increase is due to a decrease in the magnitude of the (negative) spontaneous curvature of the surfactant monolayer, as droplets swell in size. As the molar ratio of alpha-lactalbumin to AOT surpasses approximately 1:300, the partitioning of water, protein, and surfactant shifts to the excess aqueous phase, where soluble assemblies with positive curvature are detected by dynamic light scattering. Significant amounts of isooctane are solubilized in these aggregates, consistent with the formation of oil-in-water microemulsion droplets. Circular dichroism studies showed that the tertiary structure of the protein in the microemulsion is disrupted while the secondary structure is increased. In light of these findings, the protein most likely expands to a molten-globule type conformation in the AOT interfacial environment, but does not substantially unfold to become an extended chain.

  3. 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.

  4. 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.

  5. 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

    2013-10-02

    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.

  6. 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.

  7. Dielectric depolarisation and concerted collective dynamics in AOT reverse micelles with and without ubiquitin.

    PubMed

    Schmollngruber, Michael; Braun, Daniel; Oser, Daniel; Steinhauser, Othmar

    2016-02-07

    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.

  8. Risk assessments for forest trees: the performance of the ozone flux versus the AOT concepts.

    PubMed

    Karlsson, P E; Braun, S; Broadmeadow, M; Elvira, S; Emberson, L; Gimeno, B S; Le Thiec, D; Novak, K; Oksanen, E; Schaub, M; Uddling, J; Wilkinson, M

    2007-04-01

    Published ozone exposure-response relationships from experimental studies with young trees performed at different sites across Europe were re-analysed in order to test the performance of ozone exposure indices based on AOTX (Accumulated exposure Over a Threshold of X nmol mol(-1)) and AF(st)Y (Accumulated Stomatal Flux above a threshold of Y nmol m(-2) s(-1)). AF(st)1.6 was superior, as compared to AOT40, for explaining biomass reductions, when ozone sensitive species with differing leaf morphology were included in the analysis, while this was not the case for less sensitive species. A re-analysis of data with young black cherry trees, subject to different irrigation regimes, indicated that leaf visible injuries were more strongly related to the estimated stomatal ozone uptake, as compared to the ozone concentration in the air. Experimental data with different clones of silver birch indicated that leaf thickness was also an important factor influencing the development of ozone induced leaf visible injury.

  9. 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

  10. Tropospheric aerosols remote sensing over the water surface of Penang Island

    NASA Astrophysics Data System (ADS)

    Hashim, S. A.; MatJafri, M. Z.; Abdullah, K.; Lim, H. S.; Wong, C. J.; Salleh, N. Mohd.

    2006-05-01

    Tropospheric aerosols play an important role in climate change. Aerosols are typically studied over deep clear water, due to the relatively constant reflectance of water and the ability to easily separate surface and atmospheric contributions on the satellite signal. A methodology based on multi-spectral approach was employed to map tropospheric aerosols concentrations over the water areas surrounding Penang Island. The aim of this study was to estimate the pollutants concentrations using remote sensing techniques. In this study, we attempted to derive AOT (Aerosol Optical Thickness) values from the sky transmittance measurements in the visible spectrum. The transmittance values were measured at the sea surface using a handheld spectroradiometer. The correspond PM10 readings were taken simultaneously during the transmittance measurements acquisition of the imageries using a Dust Trak meter. The PCI Geomatica version 9.1 digital image processing software was used in all image-processing analyses. The results produced a linear relationship between PM10 and AOT values over the water surface of Penang Island. Finally, The PM10 concentration map over the water surface of Penang Island was generated using Kriging interpolation technique. This study has indicated the potential use of a handheld spectroradiometer for air quality study.

  11. 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.

  12. 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.

  13. Complex architecture and regulated expression of the Sox2ot locus during vertebrate development

    PubMed Central

    Amaral, Paulo P.; Neyt, Christine; Wilkins, Simon J.; Askarian-Amiri, Marjan E.; Sunkin, Susan M.; Perkins, Andrew C.; Mattick, John S.

    2009-01-01

    The Sox2 gene is a key regulator of pluripotency embedded within an intron of a long noncoding RNA (ncRNA), termed Sox2 overlapping transcript (Sox2ot), which is transcribed in the same orientation. However, this ncRNA remains uncharacterized. Here we show that Sox2ot has multiple transcription start sites associated with genomic features that indicate regulated expression, including highly conserved elements (HCEs) and chromatin marks characteristic of gene promoters. To identify biological processes in which Sox2ot may be involved, we analyzed its expression in several developmental systems, compared to expression of Sox2. We show that Sox2ot is a stable transcript expressed in mouse embryonic stem cells, which, like Sox2, is down-regulated upon induction of embryoid body (EB) differentiation. However, in contrast to Sox2, Sox2ot is up-regulated during EB mesoderm-lineage differentiation. In adult mouse, Sox2ot isoforms were detected in tissues where Sox2 is expressed, as well as in different tissues, supporting independent regulation of expression of the ncRNA. Sox2dot, an isoform of Sox2ot transcribed from a distal HCE located >500 kb upstream of Sox2, was detected exclusively in the mouse brain, with enrichment in regions of adult neurogenesis. In addition, Sox2ot isoforms are transcribed from HCEs upstream of Sox2 in other vertebrates, including in several regions of the human brain. We also show that Sox2ot is dynamically regulated during chicken and zebrafish embryogenesis, consistently associated with central nervous system structures. These observations provide insight into the structure and regulation of the Sox2ot gene, and suggest conserved roles for Sox2ot orthologs during vertebrate development. PMID:19767420

  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, 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

  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, 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

  16. 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

  17. Monitoring the activity of the Be star OT Geminorum

    NASA Astrophysics Data System (ADS)

    Arellano Ferro, A.; Sareyan, J. P.; Avila, J. J.; Gonzalez, F.; Dumont, M.; Geos

    1998-02-01

    Observations obtained in 1995-1996 of the Be star OT Geminorum are reported and show that in october 1995 the star reached a very active phase with large variations around a bright plateau, a phase of activity we have also distinguished in previous observations dating from 1960. The time scales involved are discussed and suggest that the violent variations of the activity propagate very quickly on the whole surface of the star or on a huge portion of it. No likely pulsation periods were found. The assumption that the detected activity is due to the effects of an hypothetical companion leads to conclude that such companion could not be detected by the present interferometric techniques. Partly based on observations obtained at the La Luz Observatory of the University of Guanajuato, Mexico.

  18. 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.

  19. Swift observations of MASTER OT J120451.50+265946.6 (Type Ib SN)

    NASA Astrophysics Data System (ADS)

    Margutti, Raffaella; Brown, Peter J.; Kamble, Atish; Milisavljevic, Dan; Parrent, Jerod; Soderberg, Alicia M.

    2014-11-01

    MASTER OT J120451.50+265946.6 (Atel #6634) has been recently classified as a Type Ib SN a few weeks after maximum light (Atel #6639, #6640, #6641). MASTER OT J120451.50+265946.6 exploded in NGC 4080 (distance of 15 Mpc, Karachentsev et al., 2013).

  20. 12 CFR 502.15 - How does OTS determine my size component?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 12 Banks and Banking 6 2013-01-01 2012-01-01 true How does OTS determine my size component? 502.15... size component? (a) Chart. If you are a savings association, OTS uses the following chart to calculate your size component: If your total assets are: . . . Over—* Column A But not over— Column B Your...

  1. 12 CFR 502.15 - How does OTS determine my size component?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 12 Banks and Banking 6 2014-01-01 2012-01-01 true How does OTS determine my size component? 502.15... size component? (a) Chart. If you are a savings association, OTS uses the following chart to calculate your size component: If your total assets are: . . . Over—* Column A But not over— Column B Your...

  2. 12 CFR 502.15 - How does OTS determine my size component?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 5 2011-01-01 2011-01-01 false How does OTS determine my size component? 502... determine my size component? (a) Chart. If you are a savings association, OTS uses the following chart to calculate your size component: If your total assets are: . . . Over—* Column A But not over— Column B...

  3. 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....

  4. 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,...

  5. 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,...

  6. 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,...

  7. 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....

  8. 75 FR 61572 - Open Meeting of the OTS Mutual Savings Association Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... interested in attending the meeting and members of the public who require auxiliary aid should e-mail OTS at.... The public is invited to submit written statements to the MSAAC by any one of the following methods: E-mail address: mutualcommittee@ots.treas.gov ; or Mail: to Charlotte Bahin, Designated Federal...

  9. 12 CFR 563.146 - Will the OTS permit my capital distribution?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... under 12 U.S.C. 1831o(d)(1)(B). (b) Your proposed capital distribution raises safety or soundness... 12 Banks and Banking 6 2012-01-01 2012-01-01 false Will the OTS permit my capital distribution... distribution? The OTS will review your notice or application under the review procedures in 12 CFR part...

  10. MASTER-Kislovodsk: bright OT (PSN or CV, ampl>5.2m)

    NASA Astrophysics Data System (ADS)

    Kuznetsov, N.; Shumkov, V.; Lipunov, V.; Tlatov, A.; Rebolo, R.; Serra-Ricart, M.; Senik, V.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Vladimirov, V.; Vlasenko, D.; Dormidontov, D.; Parkhomenko, A.; Gress, O.; Ivanov, K.; Budnev, N.

    2016-10-01

    MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 10h 06m 29.13s +22d 26m 43.8s with unfiltered m_OT=16.8m on 2016-10-09 00:56:53.746UT.

  11. MASTER: QSO flare (5BZQ J1312-0424) and OTs

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Shumkov, V.; Pogrosheva, T.; Popova, E.; Lipunov, V.; Podesta, R.; Levato, H.; Lopez, C.; Podesta, F.; Tlatov, A.; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Kornilov, V.; Vladimirov, V.; Ivanov, O. Gress K.; Chazov, V.

    2016-11-01

    MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 13h 12m 50.91s -04d 24m 49.1s on 2016-11-20.11222 UT. The OT unfiltered magnitude is (mlim=18.2m).

  12. MASTER-Tunka: bright 6mag ampl dwarf nova outburst and OT from MASTER-SAAO

    NASA Astrophysics Data System (ADS)

    Gress, O.; Balanutsa, P.; Lipunov, V.; Buckley, D.; Potter, S.; Budnev, N.; Ivanov, K.; Tiurina, N.; Gorbovskoy, E.; Kuznetsov, A.; Kornilov, V.; Vladimirov, V.; Chazov, V.; Kuvshinov, D.

    2016-11-01

    MASTER-Tunka auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 07h 37m 04.36s +25d 00m 54.5s on 2016-11-09.74453 UT. The OT unfiltered magnitude is (mlim=18.4m).

  13. MASTER-IAC: bright OT with ampltude more then 6.3mag

    NASA Astrophysics Data System (ADS)

    Shumkov, V.; Lipunov, V.; Rebolo, R.; Serra-Ricart, M.; Gorbovskoy, E.; Tiurina, N.; Kuznetsov, A.; Vladimirov, V.; Balanutsa, P.; Kuvshinov, D.; Kornilov, V.; Chazov, V.

    2016-11-01

    MASTER-IAC auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 12h 55m 32.84s -05d 04m 42.8s on 2016-11-17.26843 UT. The OT unfiltered magnitude is 15.7m (limit 17.5m).

  14. The 1000-th MASTER detection and SALT limit: Fast Doublet OT

    NASA Astrophysics Data System (ADS)

    Balanutsa, P.; Lipunov, V.; Gorbovskoy, E.; Buckley, D.; Kniazev, A.; Tiurina, N.; Kornilov, V.; Samus, N.; Kuznetsov, A.; Vlasenko, D.; Gorbunov, I.; Popova, E.; Vladimirov, V.; Shumkov, V.; Potter, S.; Kotze, M.; Gress, O.; Budnev, N.; Yazev, S.; Ivanov, K.; Tlatov, A.; Senik, V.; Dormidontov, D.; Parhomenko, A. V.; Yurkov, V.; Sergienko, Yu.; Gabovich, A.; Sinyakov, E.; Rebolo, R.; Serra-Ricart, M.; Lodieu, N.; Israelian, G.; Suarez-Andres, L.; Levato, Hugo; Astronomicas, Carlos Saffe Instituto de Ciencias; Espacio, de la Tierra y. del; Podesta, Ricardo; Mallamaci, Claudio; Lopez, Carlos; Podesta, Federico

    2015-12-01

    MASTER-SAAO (Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 349171) discovered the 1000th OT source at (RA, Dec) = 05h 10m 14.58s -29d 09m 00.6s on 2015-12-16.97115 UT. The OT unfiltered magnitude is 18.8m (the limit is 20.4m).

  15. 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...

  16. MASTER: high amplitude (>6.8m) optical transient and new OT

    NASA Astrophysics Data System (ADS)

    Gress, O.; Pogrosheva, T.; Lipunov, V.; Gorbovskoy, E.; Tiurina, N.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Chazov, V.; Vladimirov, V.; Shumkov, V.; Kuvshinov, D.; Ivanov, K.; Budnev, N.; Tlatov, A.; Senik, V.

    2017-02-01

    MASTER-Tunka auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 19h 12m 48.12s +37d 49m 34.6s on 2017-01-31.86338 UT. The OT unfiltered magnitude is (limit 18.4m).

  17. 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...

  18. 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

  19. Formation of octadecyltrichlorosilane (OTS) self-assembled monolayers on amorphous alumina

    NASA Astrophysics Data System (ADS)

    Kelkar, Sanket S.; Chiavetta, David; Wolden, Colin A.

    2013-10-01

    The kinetics and thermodynamics of octadecyltrichlorosilane (OTS) self-assembled monolayers (SAMs) on vapor deposited alumina were quantified. Ozone cleaning serves to create well-defined hydrophilic surfaces for OTS attachment, and the use of heptane as a solvent enables the formation of high quality SAMs under ambient conditions. The kinetics was characterized as a function of OTS concentration using contact angle goniometry, ellipsometry and Fourier transform infrared (FTIR) spectroscopy. The kinetics of SAM formation and the saturation contact angle (∼100̊) on alumina are comparable to what has been observed for OTS on silicon. The free energy of adsorption with ΔGads values ranged from -7.5 to -5.4 kcal/mol, and the SAMs were stable up to 230 ̊C. The critical surface tension of the OTS monolayer was found to be 21.4 dyne/cm.

  20. 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

  1. 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

  2. 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.

  3. 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

  4. Desert dust aerosol air mass mapping in the western Sahara, using particle properties derived from space-based multi-angle imaging

    NASA Astrophysics Data System (ADS)

    Kahn, Ralph; Petzold, Andreas; Wendisch, Manfred; Bierwirth, Eike; Dinter, Tilman; Esselborn, Michael; Fiebig, Marcus; Heese, Birgit; Knippertz, Peter; Müller, Detlef; Schladitz, Alexander; von Hoyningen-Huene, Wolfgang

    2009-02-01

    ABSTRACT 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.

  5. 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.

  6. ENCAPSULATED AEROSOLS

    DTIC Science & Technology

    acetate, polymerized rapidly and produced some polymer film encapsulation of the aerosol droplets. A two-stage microcapsule generator was designed...encapsulating material, the generator also produced microcapsules of dibutyl phosphite in polyethylene, nitrocellulose, and natural rubber.

  7. 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.

  8. 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

  9. Issues in Data Fusion for Use in an Interactive Online Analysis System using MODIS Terra and Aqua Daily Aerosol Data

    NASA Astrophysics Data System (ADS)

    Gopalan, A.; Zubko, V.; Leptoukh, G. G.

    2008-12-01

    Data Fusion defined here as a consisting of merging and interpolation is a method of combining spatio- temporally near-coincident satellite observations to provide complete global or regional maps of geophysical variables for comparison with transport models and ground station observations. We investigate various methods, challenges and limitations of data fusion, with and without interpolation, as a first step towards merging datasets archived in the NASA Goddard Earth Sciences (GES) Data and Information Services Center (DISC) and made public through the Goddard Interactive Online Visualization and Analysis Infrastructure (Giovanni) data portals. As a prototype for the data fusion algorithm, this study uses daily global observations of Aerosol Optical Thickness (AOT), as measured by the MODerate resolution Imaging Spectroradiometer (MODIS) onboard the Terra and Aqua satellites. The goal is to develop a very fast online method for data fusion for implementation into Giovanni. We demonstrate three different methods for fusion (without interpolation): Simple Arithmetic Averaging (SIM), Maximum Likelihood Estimate (MLE) and Weighting by Pixel Counts (WPC). All three methods are roughly comparable, with the MLE (SIM) being slightly preferable when validating with respect to the AOT standard deviations (AOT means). To evaluate the fused product, we introduce two confidence functions, which characterize the percentage of the fused AOT pixels as a function of the relative deviation of the fused AOT from the initial Terra and Aqua AOTs. Gaps in the daily global maps of AOT's arise from regions in sun glint, clouds, gaps between orbit tracks at low latitudes, and other sources of missing data. Data fusion with spatial interpolation produces spatially contiguous fields (global and regional maps) for dust event tracking and comparison with and input to 3-D global and regional models. Eight combinations of merger-interpolation are applied to scenes with regular and irregular

  10. 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.

  11. 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.

  12. 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...

  13. 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...

  14. 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...

  15. 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...

  16. 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...

  17. 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.

  18. 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.

  19. 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.

  20. Crystallization and reentrant melting of charged colloids in nonpolar solvents.

    PubMed

    Kanai, Toshimitsu; Boon, Niels; Lu, Peter J; Sloutskin, Eli; Schofield, Andrew B; Smallenburg, Frank; van Roij, René; Dijkstra, Marjolein; Weitz, David A

    2015-03-01

    We explore the crystallization of charged colloidal particles in a nonpolar solvent mixture. We simultaneously charge the particles and add counterions to the solution with aerosol-OT (AOT) reverse micelles. At low AOT concentrations, the charged particles crystallize into body-centered-cubic (bcc) or face-centered-cubic (fcc) Wigner crystals; at high AOT concentrations, the increased screening drives a thus far unobserved reentrant melting transition. We observe an unexpected scaling of the data with particle size, and account for all behavior with a model that quantitatively predicts both the reentrant melting and the data collapse.

  1. Effect of compressed CO2 on the critical micelle concentration and aggregation number of AOT reverse micelles in isooctane.

    PubMed

    Chen, Jing; Zhang, Jianling; Han, Buxing; Feng, Xiaoying; Hou, Minqiang; Li, Wenjing; Zhang, Zhaofu

    2006-10-25

    The effect of compressed CO2 on the critical micelle concentration (cmc) and aggregation number of sodium bis-2-ethylhexylsulfosuccinate (AOT) reverse micelles in isooctane solution was studied by UV/Vis and fluorescence spectroscopy methods in the temperature range of 303.2-318.2 K and at different pressures or mole fractions of CO2 (X(CO2)). The capacity of the reverse micelles to solubilize water was also determined by direct observation. The standard Gibbs free energy (DeltaGo(m)), standard enthalpy (DeltaHo(m)), and standard entropy (DeltaSo(m)) for the formation of the reverse micelles were calculated by using the cmc data determined. It was discovered that the cmc versus X(CO2) curve and the DeltaGo(m) versus X(CO2) curve for a fixed temperature have a minimum, and the aggregation number and water-solubilization capacity of the reverse micelles reach a maximum at the X(CO2) value corresponding to that minimum. These results indicate that CO2 at a suitable concentration favors the formation of and can stabilize AOT reverse micelles. A detailed thermodynamic study showed that the driving force for the formation of the reverse micelles is entropy.

  2. Influence of aza crown ethers on the electric percolation of AOT/isooctane/water (w/o) microemulsions.

    PubMed

    Dasilva-Carvalhal, J; Fernández-Gándara, D; García-Río, L; Mejuto, J C

    2006-09-15

    A study was carried out on the influence of different aza crown ethers on the electric percolation of AOT/isooctane/water microemulsions. A dual behavior of the aza crown ethers with regard to the percolative phenomenon was observed: low additive concentration causes an increase in the percolation temperature, whereas at high additive concentration a reduction in the percolation temperature of the system was observed. This dual behavior allowed us to define the compensation concentration, which corresponds the aza crown ether concentration at which there is no effect on the percolative phenomenon. We observed a correlation between the effect exerted by the aza crown ethers and the size of the cavity. This shows the importance of the capacity to complexate Na(+) and solubilize it in the interface and the continuous medium on the electric percolation. We also observed a correlation between the effect of the aza crown ethers on the percolation temperature and their external size. This shows the importance of their inclusion in the interface on the percolative phenomenon. Such an inclusion modifies the properties of the AOT film, facilitating the exchange of matter between droplets. A satisfactory multiparametric correlation between the compensation concentration, the distribution of the aza crown ether between water and 1-octanol, and the number of electron-donor atoms (O and N) in the crown ether was obtained. The effects have been compared with those corresponding to the crown ethers.

  3. 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

  4. 12 CFR 563b.200 - What actions may OTS take on my application?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... record under part 563e of this chapter and your business plan to determine how you will serve the... that you will serve. (2) OTS may deny your application if your business plan does not demonstrate...

  5. 12 CFR 563b.200 - What actions may OTS take on my application?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... record under part 563e of this chapter and your business plan to determine how you will serve the... that you will serve. (2) OTS may deny your application if your business plan does not demonstrate...

  6. Multiangle photopolarimetric aerosol retrievals in the vicinity of clouds: Synthetic study based on a large eddy simulation

    NASA Astrophysics Data System (ADS)

    Stap, F. A.; Hasekamp, O. P.; Emde, C.; Röckmann, T.

    2016-11-01

    We investigate the effect of cloud contamination and 3-D radiative transfer effects on aerosol retrievals from multiangle photopolarimetric measurements in the vicinity of clouds. To this end multiangle, multiwavelength photopolarimetric observations are simulated using a 3-D radiative transfer model for scenes with realistic cloud properties, based on a large eddy simulation. Spatial resolutions of 2 × 2, 4 × 4, and 6 × 6 km2 have been considered. It is found that a goodness-of-fit criterion efficiently filters out cloud contamination. However, it does not filter out all scenes that are affected by 3-D radiative effects, resulting in small biases in the retrieved aerosol optical thickness (AOT) and single-scattering albedo (SSA). We also found that measurements at higher spatial resolution (2 × 2 km2) do not result in retrievals closer to clouds compared to measurements at coarser spatial resolutions (4 × 4 and 6 × 6 km2). If cloud parameters are fitted simultaneously with aerosol parameters using a 1-D radiative transfer model and the Independent Pixel Approximation, more successful retrievals are obtained in partially cloudy scenes and in the vicinity of clouds. This effect is most apparent at 6 × 6 km2 and only marginal at 2 × 2 km2 resolution. The retrieved aerosol AOT and SSA from the simultaneous aerosol and cloud retrievals still have a small bias, like the aerosol-only retrievals. We conclude that in order to substantially improve aerosol retrievals in the vicinity of clouds, a retrieval algorithm is needed that takes into account 3-D radiative transfer effects.

  7. 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.

  8. MASTER discovery: blue bright OT during FERMI 496473540 (GRB160925A) inspection

    NASA Astrophysics Data System (ADS)

    Gress, O.; Lipunov, V.; Buckley, D.; Tiurina, N.; Gorbovskoy, E.; Balanutsa, P.; Kuznetsov, A.; Kornilov, V.; Vladimirov, V.; Shumkov, V.; Pogrosheva, T.; Rebolo Lopez, R.; Serra Ricart, M.; Podesta, R.; Levato, H.; Potter, S.; Lodieu, N.; Saffe, C.; Lopez, C.; Podesta, F.

    2016-09-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 22h 28m 17.90s -14d 56m 57.4s on 2016-09-25.75053 UT during automatically inspection of Fermi trigger 496473540 ( http://gcn.gsfc.nasa.gov/other/496473540.fermi ). The OT unfiltered magnitude is (limit 19.7m).

  9. 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.

  10. 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.

  11. 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

  12. Solvation dynamics of coumarin 153 embedded in AOT + phenol organogels studied by time-resolved fluorescence spectroscopy

    NASA Astrophysics Data System (ADS)

    Nishiyama, Katsura; Takata, Kei; Watanabe, Keiichi; Shigematsu, Hirotake

    2012-03-01

    We investigate solvation dynamics of organogel utilizing ps-ns fluorescence spectroscopy. The organogel studied in this Letter comprises bis(2-ethylhexyl) sulfosuccinate (AOT) and p-chlorophenol in the m-xylene solvent, that produce an organogel architecture with self-assembly. Within the organogel, an emitting probe, coumarin 153 (C153), is embedded. We then obtain dynamic response functions of solvation derived from the time-resolved fluorescence spectra of C153. We propose that total energy of the C153-organogel system relaxes with a relaxation time of 3.9 ns, whereas the entire rearrangement of the organogel structure around C153 is achieved with that of 6.1 ns, respectively.

  13. 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

    2005-03-04

    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.

  14. Transformation of aerosol in Planetary Boundary Layer over the Baltic Sea

    NASA Astrophysics Data System (ADS)

    Makuch, Przemyslaw; Petelski, Tomasz; Piskozub, Jacek; Jankowski, Andrzej; Zieliński, Tymon; Rozwadowska, Anna; Markuszewski, Piotr; Zawadzka, Olga

    2013-04-01

    Aerosols are one of the most important components of the atmosphere. The content and composition of aerosols in the atmosphere depends on their origin. In maritime areas transformation of aerosols in the atmosphere may occur. This depends on many factors, such as wind speed and direction, humidity and emission from the sea surface. The transformation of aerosols in the Planetary Boundary Layer over the Baltic Sea is replacing other sources of aerosols to aerosols composed of sea salt. When the air passing over the Baltic aerosol optical thickness (AOT) initially decreases and then increases in strong winds due to increase of the marine aerosol content in the layer. This type of change can be followed with use of many numerical experiments performed on the model of the transformation of aerosols in the Planetary Boundary Layer. This model consists of two parts, dynamic and optical. The dynamic part is based on the repeated numerical solution of the equation of diffusion for different particle size and optical properties. The result of the dynamic part provides vertical profiles of aerosol size distributions. Optical module to calculate the relative cross sections for the weakening used Mie single process. We compare data from numerical experiments with data from in situ experiments and with data from MODIS (Moderate Resolution Imaging Spectroradiometer) on board of Terra and Aqua satellite. From the resulting comparisons received correlations are in order as 0.789 and 0.862. What indicates a good correlation between the data from numerical experiment and in situ data or MODIS data. Acknowledgements: The support for this study was provided by the project Satellite Monitoring of the Baltic Sea Environment - SatBałtyk founded by European Union through European Regional Development Fund contract No. POIG 01.01.02-22-011/09

  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.

  16. 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.

  17. 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.

  18. 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

  19. ENCAPSULATED AEROSOLS

    DTIC Science & Technology

    materials determine the range of applicability of each method. A useful microencapsulation method, based on coagulation by inertial force was developed...The generation apparatus, consisting of two aerosol generators in series, was utilized to produce many kinds of microcapsules . A fluid energy mill...was found useful for the production of some microcapsules . The permeability of microcapsule films and the effect of exposure time and humidity were

  20. 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.

  1. 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

  2. Short-Term H α Line Variations in Classical Be Stars: 59 Cyg and OT Gem

    NASA Astrophysics Data System (ADS)

    Paul, K. T.; Shruthi, S. B.; Subramaniam, Annapurni

    2017-03-01

    We present the optical spectroscopic study of two classical Be stars, 59 Cyg and OT Gem obtained over a period of few months in 2009. We detected a rare triple-peak H α emission phase in 59 Cyg and a rapid decrease in the emission strength of H α in OT Gem, which are used to understand their circumstellar disks. We find that 59 Cyg is likely to be rapid rotator, rotating at a fractional critical rotation of ˜0.80. The radius of the H α emission region for 59 Cyg is estimated to be R d/ R ∗ ˜ 10.0, assuming a Keplerian disk, suggesting that it has a large disk. We classify stars which have shown triple-peaks into two groups and find that the triple-peak emission in 59 Cyg is similar to ζ Tau. OT Gem is found to have a fractional critical rotation of ˜0.30, suggesting that it is either a slow rotator or viewed in low inclination. In OT Gem, we observed a large reduction in the radius of the H α emission region from ˜6.9 to ˜1.7 in a period of three months, along with the reduction in the emission strength. Our observations suggest that the disk is lost from outside to inside during this disk loss phase in OT Gem.

  3. 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.

  4. Radiative Energetics of Mineral Dust Aerosol over Zhangye China during the AMY 2008 Field Campaign

    NASA Astrophysics Data System (ADS)

    Hansell, R. A.; Tsay, S.; Ji, Q.; Hsu, C.; Bell, S.; Li, C.; Wang, C.

    2010-12-01

    In support of the DOE ARM program, NASA Goddard’s mobile ground-based laboratories (SMART-COMMIT) were deployed to Zhangye China (39.082°N; 100.276°E) from April-June 2008 as an ARM Ancillary Facility (AAF) to support the Asian Monsoon Year (AMY) field study. The primary objective at Zhangye, a semi-arid region located between the Taklimakan and Gobi deserts, was to both capture and characterize dust aerosol near the source region and to determine its direct aerosol radiative effects (DARE). To facilitate this study, the AAF’s Atmospheric Emitted Radiance Interferometer (AERI), a key instrument for spectrally characterizing the thermal IR, is employed to retrieve the daytime/nighttime dust IR aerosol optical thickness (AOT) for several notable dust events. Regional dust microphysical and mineralogy measurements are also used for developing a representative aerosol optical model of dust single-scattering properties. The retrieved AOT are then inputted into a 1-D radiative transfer model constrained by local measurements to evaluate dust’s local instantaneous shortwave (SW) and longwave (LW) DARE at the surface and top of the atmosphere (TOA) along with the heating rate profiles under cloud-free atmospheres. Comparisons of the SW DARE are made with a previous study over the same area using broadband data from thermal dome effect corrected pyranometers and the significance of the LW effects relative to the SW is examined. This study is part of an on-going effort to complete a global assessment of dust DARE for the major dust source regions of the world.

  5. Spectral Measurements of Aerosol Absorption from UV to VISIBLE

    NASA Astrophysics Data System (ADS)

    Krotkov, N. A.; Labow, G.; Herman, J.; Bhartia, P. K.; Slusser, J.; Durham, B.; Janson, G.; Wilson, C.; Disterhoft, P.; Cede, A.; Abuhassan, N.; Eck, T. F.; Holben, B.; Bais, A.; Rapsomanikis, S.

    2007-05-01

    Amount of solar radiation reaching the Earth's surface can be strongly influenced by aerosol absorption. The aerosol absorption optical thickness (AAOT) in the visible and near IR (440 nm- 1020nm) is routinely produced from almucantar measurements made by the CIMEL instruments in the AERONET network. AAOT in the UV (300nm- 368nm) have been derived from the total and diffuse hemispherical flux measurements made by UV- Multifilter Rotating Shadowband Radiometer (UV-MFRSR, Yankee Environmental Systems, Inc.) instruments. However, no direct comparisons between these two methods exist because the CIMEL wavelengths (used in almucantar retrievals) do not overlap with the UV-MFRSR wavelengths. To enable direct comparisons between the two techniques, we have modified our UV-MFRSR, part of USDA UVB Monitoring and Research Network, by replacing standard 300nm filter with 440nm filter used in AERONET network. The instrument has been deployed at Mauna Loa Observatory, at NASA GSFC in Greenbelt, MD (July 2005 - June 2006) and during SCOUT-03 field campaign in Thessaloniki, Greece in July 2006. During these deployments the instrument's calibration was monitored daily using co-located AERONET and BREWER direct sun measurements of aerosol extinction optical thickness (AOT). Between the deployments the instrument was thoroughly calibrated at the NOAA Central UV Calibration Facility in Boulder, Colorado. We find that the UV-MSFRSR instrument is highly susceptible to calibration drifts. However, these drifts can be accurately assessed using AERONET and BREWER direct sun data. After correcting for these calibration changes, the AAOT was inferred by fitting the measurements of global and diffuse atmospheric transmittances with the forward RT model independently at each spectral channel. The AOT data and ancillary measurements of aerosol column particle size distribution and refractive index in the visible wavelengths (by CIMEL sun-sky almucantar inversions), direct -sun column NO2 and

  6. 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.

  7. The photophysics of 7-(N,N'-diethylamino)coumarin-3-carboxylic acid in water/AOT/isooctane reverse micelles: an excitation wavelength dependent study.

    PubMed

    Chatterjee, Aninda; Maity, Banibrata; Seth, Debabrata

    2013-02-14

    In this manuscript we have studied the photophysics of 7-(N,N'-diethylamino)coumarin-3-carboxylic acid (7-DCCA) in water/AOT/isooctane reverse micelles. For this purpose we have used steady state absorption and fluorescence emission spectroscopy and time resolved fluorescence spectroscopy. We have studied the spectral behaviour of 7-DCCA inside the water/AOT/isooctane reverse micelles with variation of excitation wavelength. We have studied the dynamics of solvent and rotational relaxation by using two different excitation wavelengths (λ(exi) = 375 nm and λ(exi) = 405 nm). We have observed the excitation wavelength dependent dynamics of 7-DCCA in the reverse micelles. The fluorescence quantum yield, decay time, solvent relaxation time and rotational relaxation time of 7-DCCA in reverse micelles vary with the excitation wavelength. A two step and wobbling-in-cone model was used to interpret the rotational relaxation dynamics of 7-DCCA in reverse micelles.

  8. 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.

  9. Expression and developmental regulation of oxytocin (OT) and oxytocin receptors (OTR) in the enteric nervous system (ENS) and intestinal epithelium.

    PubMed

    Welch, Martha G; Tamir, Hadassah; Gross, Kara J; Chen, Jason; Anwar, Muhammad; Gershon, Michael D

    2009-01-10

    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 approximately 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.

  10. 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

  11. A six year satellite-based assessment of the regional variations in aerosol indirect effects

    NASA Astrophysics Data System (ADS)

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

    2008-12-01

    this region dust aerosol concentration is much greater than the anthropogenic or sea salt components. However, elevated dust in this region may also absorb solar radiation and warm the atmosphere, stabilizing the atmosphere as evidenced by weak vertical motion during the summer (0.02 Pa s-1) when AOT is greatest. Lower average cloud fraction compared to other regions allows the absorbing effect to offset the cooling effect associated with increasing CCN. The western Atlantic and Pacific oceans have large anthropogenic aerosol concentrations transported from the United States and China respectively and produce modest anthropogenic AIE (0.7, 0.9 Wm-2) in these regions as expected. Anthropogenic AIE was also present off the West African coast corresponding to aerosols produced from seasonal biomass burning. Interestingly, atmospheric conditions were not particularly favorable for cloud formation compared to the other regions during the times where AIE was observed. Overall, we are able to conclude that aerosol type, atmospheric conditions and their relative vertical distributions are a key factors as to whether or not significant AIE occurs and simple correlations between AOT and cloud properties are insufficient to explain the AIE.

  12. 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

  13. 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.

  14. 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.

  15. Fourier transform infrared spectra studies of protein in reverse micelles: effect of AOT/isooctane on the secondary structure of alpha-chymotrypsin.

    PubMed

    Chang, Q; Liu, H; Chen, J

    1994-06-12

    The amide I region Fourier transform infrared (FTIR) spectra of alpha-chymotrypsin have been studied in deuterium oxide (D2O) solution and also in reverse micellar solution of AOT/isooctane. The Fourier second derivative was applied to all spectra, revealing that the amide I band of alpha-chymotrypsin in D2O and in reverse micellar solution consists of nine components. The band frequencies are assigned to alpha-helix, beta-sheet, random and turn structure. The second derivative spectra of alpha-chymotrypsin have been shifted in the reverse micellar solution of AOT/isooctane in comparison with its spectra in D2O. This shift has also changed the intensity of each band. Through accurate measurement of the band intensities, the relative amount of different structure of alpha-chymotrypsin can be estimated. The comparison of the calculated results obtained in D2O with those obtained in reverse micellar solution provides the possibility to analyze the effect of reverse micellar solution of AOT/isooctane on the secondary structure of alpha-chymotrypsin. The results indicate that the reverse micellar solution has decreased the amount of alpha-helix and beta-sheet structure and increased the amount of random and turn structure in alpha-chymotrypsin. The increase of the amount of random structure might loosen the structure of alpha-chymotrypsin and change the activity of the enzyme.

  16. Brazilian version of an assessment tool for the evaluation of work organizational aspects (AOT) by the NIOSH WMSD Research Consortium: translation and application in industrial sectors.

    PubMed

    Batistão, Mariana V; Alcântara, Carolina C; Pissinato, Isabella G; Alem, Michele E R; Coury, Helenice J C G

    2012-01-01

    Work organization affects the production of a company as well as the health of employees. It is a challenge to create sustainable production systems with the least harm to the health. An observational assessment tool was developed by the NIOSH--WMSD Research Consortium and adapted by the SHARP study. The objectives were to translate this assessment tool into Brazilian Portuguese (as the Avaliação de Aspectos Organizacionais do Trabalho--AOT) and to evaluate its applicability in an industrial setting. The AOT final translated version was obtained after a consensus by the research team. Difficulties arose in applying the translated version due to technical terms with no direct equivalents in Portuguese, nonexcluding or similar alternatives, and questions that gave room for various interpretations, besides the great complexity of the tasks performed in the sectors. Despite that, the results suggest that AOT was sensitive for discriminating differences between sectors. Nevertheless, for better application of this tool in complex industrial environments, it is necessary: training and consensus among evaluators, familiarity with organizational aspects of the occupational settings evaluated. Also for assuring the internal validity of the analysis, might be necessary, the creation of subdivisions in the sectors evaluated if the tasks vary significantly intra-sector. The present report can help to understand the difficulties inherent to the evaluation of organizational aspects on a collective level and also the possible implications related to the translation of this assessment into other languages.

  17. 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.

  18. 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.

  19. Positive cooperativity in substrate binding of human prostatic acid phosphatase entrapped in AOT-isooctane-water reverse micelles.

    PubMed

    Luchter-Wasylewska, Ewa; Iciek, Małgorzata

    2004-05-15

    The kinetics of 1-naphthyl phosphate and phenyl phosphate hydrolysis, catalyzed by human prostatic acid phosphatase (PAP) entrapped in AOT-isooctane-water reverse micelles, has been studied over surfactant hydration degree (w0) range 5 to 35. Continuous spectrophotometric acid phosphatase assays, previously prepared, were employed. PAP was catalytically active over the whole w0 studied range. In order to determine steady-state reaction constants the experimental data were fitted to Hill rate equation. Positive cooperativity in substrate binding was observed, as it was earlier found in aqueous solutions. The extent of cooperativity (expressed as the value of the Hill cooperation coefficient h) increased from 1 to 4, when the micellar water-pool size was growing, at fixed enzyme concentration. In the plots of catalytic activity (kcat) versus w0, the maxima have been found at w0=10 (pH 5.6) and 23 (pH 3.8). It is suggested that catalytically active monomeric and dimeric PAP forms are entrapped in reverse micelles of w0=10 and 23, respectively.

  20. 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

  1. Coherent uncertainty analysis of aerosol measurements from multiple satellite sensors

    NASA Astrophysics Data System (ADS)

    Petrenko, M.; Ichoku, C.

    2013-07-01

    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 7%. Squared correlation coefficient (R2) values of the satellite AOD retrievals relative to AERONET exceeded 0.8 for many of the analyzed products, while root mean square error (RMSE) values for most of the AOD products were within 0.15 over land and 0.07 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 land cover types. It was observed that while MODIS, MISR, and SeaWiFS provide accurate retrievals over most of the land cover 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 closed shrublands more accurately than the other sensors, while POLDER, which

  2. 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

  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. 12 CFR 502.26 - How does OTS calculate the semi-annual assessment for savings and loan holding companies?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... condition. OTS determines the amount of each component under §§ 502.27 through 502.29 of this part. (b) For... reflect OTS costs of supervising the holding company structure and: (i) There are multiple top-tier holding companies in the holding company structure; (ii) The top-tier holding company is organized...

  6. 12 CFR 502.28 - How does OTS determine the organizational form component for a savings and loan holding company?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... organizational form component by adding the base assessment to your risk/complexity component, and multiplying... 12 Banks and Banking 5 2010-01-01 2010-01-01 false How does OTS determine the organizational form...-Calculation of Assessments § 502.28 How does OTS determine the organizational form component for a savings...

  7. 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

  8. 12 CFR 502.26 - How does OTS calculate the semi-annual assessment for savings and loan holding companies?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... follows: (1) OTS will assess a base assessment amount of $3,500 on responsible savings and loan holding...-site supervision of a noncomplex, low risk savings and loan holding company structure. OTS will... savings and loan holding companies: a component based on the risk or complexity of the savings and...

  9. 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.

  10. Spectroscopic Classification of MASTER OT J081506.13+381123.3 as a Type Ia Supernova

    NASA Astrophysics Data System (ADS)

    Rui, Liming; Li, Wenxiong; Chen, Zhihao; Xiang, Danfeng; Wang, Xiaofeng; Zhang, Tianmeng; Zhang, Jichen; Zhang, Ziyan; Luo, Zhe; Cui, Can; Li, Yaxin; ), Xinhang Shen

    2017-01-01

    We obtained an optical spectrum (range 360-860 nm) of MASTER OT J081506.13+381123.3 (see ATEL #9971), discovered by MASTER robotic Net, on UT Jan.20.6 2017 with the 2.16-m telescope (+BFOSC) at Xinglong Station of National Astronomical Observatories of China (NAOC).

  11. 12 CFR 516.15 - Must I meet with OTS before I file my application?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... with OTS before filing your application. You must submit a draft business plan before this meeting. (2... you to submit a draft business plan or other relevant information before this meeting. (b) Contacting... pre-filing meeting or a draft business plan, the Regional Office will determine whether it...

  12. 12 CFR 516.15 - Must I meet with OTS before I file my application?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... with OTS before filing your application. You must submit a draft business plan before this meeting. (2... you to submit a draft business plan or other relevant information before this meeting. (b) Contacting... pre-filing meeting or a draft business plan, the Regional Office will determine whether it...

  13. 12 CFR 563b.205 - May a court review OTS's final action on my conversion?

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    .... Court of Appeals for the District of Columbia Circuit, to review the action under 12 U.S.C. 1464(i)(2)(B... 12 Banks and Banking 6 2013-01-01 2012-01-01 true May a court review OTS's final action on my conversion? 563b.205 Section 563b.205 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF...

  14. 12 CFR 563b.205 - May a court review OTS's final action on my conversion?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    .... Court of Appeals for the District of Columbia Circuit, to review the action under 12 U.S.C. 1464(i)(2)(B... 12 Banks and Banking 6 2014-01-01 2012-01-01 true May a court review OTS's final action on my conversion? 563b.205 Section 563b.205 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF...

  15. 12 CFR 563b.205 - May a court review OTS's final action on my conversion?

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    .... Court of Appeals for the District of Columbia Circuit, to review the action under 12 U.S.C. 1464(i)(2)(B... 12 Banks and Banking 6 2012-01-01 2012-01-01 false May a court review OTS's final action on my conversion? 563b.205 Section 563b.205 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF...

  16. 12 CFR 563b.205 - May a court review OTS's final action on my conversion?

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    .... Court of Appeals for the District of Columbia Circuit, to review the action under 12 U.S.C. 1464(i)(2)(B... 12 Banks and Banking 5 2011-01-01 2011-01-01 false May a court review OTS's final action on my conversion? 563b.205 Section 563b.205 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF...

  17. 12 CFR 563b.205 - May a court review OTS's final action on my conversion?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    .... Court of Appeals for the District of Columbia Circuit, to review the action under 12 U.S.C. 1464(i)(2)(B... 12 Banks and Banking 5 2010-01-01 2010-01-01 false May a court review OTS's final action on my conversion? 563b.205 Section 563b.205 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF...

  18. 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

    ...In this notice of proposed rulemaking, the Federal Deposit Insurance Corporation (``FDIC'') proposes to rescind and remove a regulation entitled ``Disclosure and Reporting of CRA-Related Agreements.'' This regulation was included in the regulations that were transferred to the FDIC from the Office of Thrift Supervision (``OTS'') on July 21, 2011, in connection with the implementation of......

  19. Use of thermal cycling to reduce adhesion of OTS coated coated MEMS cantilevers

    NASA Astrophysics Data System (ADS)

    Ali, Shaikh M.; Phinney, Leslie M.

    2003-01-01

    °Microelectromechanical systems (MEMS) have enormous potential to contribute in diverse fields such as automotive, health care, aerospace, consumer products, and biotechnology, but successful commercial applications of MEMS are still small in number. Reliability of MEMS is a major impediment to the commercialization of laboratory prototypes. Due to the multitude of MEMS applications and the numerous processing and packaging steps, MEMS are exposed to a variety of environmental conditions, making the prediction of operational reliability difficult. In this paper, we investigate the effects of operating temperature on the in-use adhesive failure of electrostatically actuated MEMS microcantilevers coated with octadecyltrichlorosilane (OTS) films. The cantilevers are subjected to repeated temperature cycles and electrostatically actuated at temperatures between 25°C and 300°C in ambient air. The experimental results indicate that temperature cycling of the OTS coated cantilevers in air reduces the sticking probability of the microcantilevers. The sticking probability of OTS coated cantilevers was highest during heating, which decreased during cooling, and was lowest during reheating. Modifications to the OTS release method to increase its yield are also discussed.

  20. 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,…

  1. 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.

  2. 12 CFR 502.25 - How does OTS determine my complexity component?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... ASSESSMENTS AND FEES Assessments Savings Associations-Calculation of Assessments § 502.25 How does OTS determine my complexity component? If you are a savings association and your portfolio exceeds any of the... paragraph (c) of this section. If your portfolio does not exceed any of the thresholds in paragraph (a)...

  3. 75 FR 76524 - Closed Meeting of the OTS Mutual Savings Association Advisory Committee

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-08

    .... SUMMARY: The OTS Mutual Savings Associations Advisory Committee (MSAAC) will convene a meeting on Monday... meeting will be held on Monday, December 20, 2010, at Noon, Eastern Time. ADDRESSES: The meeting will be... Savings Association Advisory Committee will convene a closed meeting on Monday, December 20,...

  4. 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

  5. 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.

  6. Enzyme hyperactivity in AOT water-in-oil microemulsions is induced by 'lone' sodium counterions in the water-pool.

    PubMed

    Oldfield, Christopher; Freedman, Robert B; Robinson, Brian H

    2005-01-01

    Water-in-oil microemulsions are thermodynamically stable single-phase dispersions of water and surfactant within a continuous oil phase. The classical ternary system, based on the surfactant sodium bis(2-ethylhexyl)sulfosuccinate ('AOT'), water and an alkane such as n-heptane, is an optically transparent monodispersion of spherical water-droplets coated with a close-packed surfactant monolayer and the droplet radius is, to a good first approximation, directly proportional to the molar water: surfactant ratio, R. Enzymes dissolved in the water droplets retain activity and stability. These systems have attracted interest as media for biotransformations. Principally based upon studies in AOT-stabilized w/o microemulsions, a peculiar feature of the kinetics of enzyme-catalyzed reactions has long been apparent: the reaction rate characteristically increases from around zero at R=3, through a maximum, in the range R= 10-20, and thereafter decreases again, so that plots of rate vs. R are characteristically 'bell-shaped'. Furthermore, at optimal R, enzymes seem to be 'hyperactive', i.e., they are more active, by a modest but significant factor of 2-3-fold, than in aqueous solution. In this paper we propose the hypothesis that this kind of R-dependence arises because of the presence of freely mobile lone surfactant counterions (Na+) within the water-pool. These ions have no charge partners within the water pool and consequently have a high electrochemical potential. According to our model, lone counterions facilitate the hydrolysis of ester or amide substrates, for example, by stabilizing the tetrahedral intermediate formed during the reaction through ion-pairing with the carbonyl oxygen of the substrate, thus facilitating transfer of negative charge from the carbonyl carbon as it is attacked by the incoming nucleophile. An expression for the relationship between the concentration of free counterions in the water-pool and the compositional parameter R leads directly

  7. 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

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false How does OTS determine the risk/complexity...-Calculation of Assessments § 502.27 How does OTS determine the risk/complexity component for a savings and loan holding company? (a) OTS computes the risk/complexity component for responsible savings and...

  8. Long-Term Global Aerosol Products from NASA Reanalysis MERRA-2 Available at GES DISC

    NASA Astrophysics Data System (ADS)

    Shen, S.; Ostrenga, D.; Vollmer, B.

    2015-12-01

    Over 35 years of model simulated global aerosol products from NASA atmospheric reanalysis, second Modern-Era Retrospective analysis for Research and Applications (MERRA-2) are published in summer 2015 at NASA Goddard Earth Science Data and Information Services Center (GES DISC). The MERRA-2 covers the period 1980-present, continuing as an ongoing climate analysis. Aerosol assimilation is included throughout the period, using MODIS, MISR, AERONET, and AVHRR (in the pre-EOS period). The aerosols are assimilated by using the Goddard Chemistry Aerosol Radiation and Transport (GOCART) model, which interact directly with the radiation parameterization, and radiatively coupled with atmospheric model dynamics in the Goddard Earth Observing System Model, Version 5 (GEOS-5). The data have been grouped into five datasets, including variables such as: dust column mass density, dust column mass density - PM 2.5, dust deposition, SO2 column mass density, aerosol optical depth analysis, total aerosol extinction AOT 550nm, black carbon emission etc. The data are available at hourly or 3-hourly and monthly at horizontal spatial resolution of 0.5x0.625 degrees (latitude x longitude) and 72 eta coordinate levels extending to 0.01 hPa for 3-dimensional variables. This presentation will document data access services at GES DISC and how to explore the data through the online visualization tool (Giovanni). As use cases, aerosol transportation of selected events will be demonstrated: a) SO2 column mass density from volcano Sierra Negra (Oct 2005), stayed in the tropical atmosphere for about 20 days; b) dust column mass density from a Asian dust storm in April 2001, transported dust from Asia across Pacific to North America in about one week; and c) black carbon column mass density from a wildfire late July to early September 2010 in Russia.

  9. 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

  10. 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.

  11. 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...

  12. Microcalorimetric investigation of the solubilization of water in reversed micelles and water-in-oil microemulsions

    SciTech Connect

    Haandrikman, G.; Daane, G.J.R.; Kerkhof, F.J.M.; Os, N.M. van; Rupert, L.A.M.

    1992-10-29

    Microcalorimetry has been used to study the solubilization of water in reversed micelles and water-in-oil (w/o) microemulsions. The systems were based on Aerosol OT (AOT) and two isomerically pure sodium alkylarenesulfonates as surfactants. The solubilization of water can be described in terms of hydration of the head group (ca. three H{sub 2}O molecules per AOT), swelling of the water droplet, and phase separation. All steps are endothermic, indicating that a gain in entropy is the driving forcing for solubilization. Above 60 {degrees}C the hydration energy for AOT is strongly affected by temperature. The swelling of alkylarenesulfonate w/o microemulsions droplets in n-heptane is more endothermic than that of AOT w/o microemulsion droplets in n-heptane, indicating a significant influence of surfactant structure. 57 refs., 7 figs., 1 tab.

  13. 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.

  14. Validation of high-resolution aerosol optical thickness simulated by a global non-hydrostatic model against remote sensing measurements

    NASA Astrophysics Data System (ADS)

    Goto, Daisuke; Sato, Yousuke; Yashiro, Hisashi; Suzuki, Kentaroh; Nakajima, Teruyuki

    2017-02-01

    A high-performance computing resource allows us to conduct numerical simulations with a horizontal grid spacing that is sufficiently high to resolve cloud systems. The cutting-edge computational capability, which was provided by the K computer at RIKEN in Japan, enabled the authors to perform long-term, global simulations of air pollutions and clouds with unprecedentedly high horizontal resolutions. In this study, a next generation model capable of simulating global air pollutions with O(10 km) grid spacing by coupling an atmospheric chemistry model to the Non-hydrostatic Icosahedral Atmospheric Model (NICAM) was performed. Using the newly developed model, month-long simulations for July were conducted with 14 km grid spacing on the K computer. Regarding the global distributions of aerosol optical thickness (AOT), it was found that the correlation coefficient (CC) between the simulation and AERONET measurements was approximately 0.7, and the normalized mean bias was -10%. The simulated AOT was also compared with satellite-retrieved values; the CC was approximately 0.6. The radiative effects due to each chemical species (dust, sea salt, organics, and sulfate) were also calculated and compared with multiple measurements. As a result, the simulated fluxes of upward shortwave radiation at the top of atmosphere and the surface compared well with the observed values, whereas those of downward shortwave radiation at the surface were underestimated, even if all aerosol components were considered. However, the aerosol radiative effects on the downward shortwave flux at the surface were found to be as high as 10 W/m2 in a global scale; thus, simulated aerosol distributions can strongly affect the simulated air temperature and dynamic circulation.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Correlation of insulin-enhancing properties of vanadium-dipicolinate complexes in model membrane systems: phospholipid langmuir monolayers and AOT reverse micelles.

    PubMed

    Sostarecz, Audra G; Gaidamauskas, Ernestas; Distin, Steve; Bonetti, Sandra J; Levinger, Nancy E; Crans, Debbie C

    2014-04-22

    We explore the interactions of V(III) -, V(IV) -, and V(V) -2,6-pyridinedicarboxylic acid (dipic) complexes with model membrane systems and whether these interactions correlate with the blood-glucose-lowering effects of these compounds on STZ-induced diabetic rats. Two model systems, dipalmitoylphosphatidylcholine (DPPC) Langmuir monolayers and AOT (sodium bis(2-ethylhexyl)sulfosuccinate) reverse micelles present controlled environments for the systematic study of these vanadium complexes interacting with self-assembled lipids. Results from the Langmuir monolayer studies show that vanadium complexes in all three oxidation states interact with the DPPC monolayer; the V(III) -phospholipid interactions result in a slight decrease in DPPC molecular area, whereas V(IV) and V(V) -phospholipid interactions appear to increase the DPPC molecular area, an observation consistent with penetration into the interface of this complex. Investigations also examined the interactions of V(III) - and V(IV) -dipic complexes with polar interfaces in AOT reverse micelles. Electron paramagnetic resonance spectroscopic studies of V(IV) complexes in reverse micelles indicate that the neutral and smaller 1:1 V(IV) -dipic complex penetrates the interface, whereas the larger 1:2 V(IV) complex does not. UV/Vis spectroscopy studies of the anionic V(III) -dipic complex show only minor interactions. These results are in contrast to behavior of the V(V) -dipic complex, [VO2 (dipic)](-) , which penetrates the AOT/isooctane reverse micellar interface. These model membrane studies indicate that V(III) -, V(IV) -, and V(V) -dipic complexes interact with and penetrate the lipid interfaces differently, an effect that agrees with the compounds' efficacy at lowering elevated blood glucose levels in diabetic rats.

  20. Aerosol algorithm evaluation within aerosol-CCI

    NASA Astrophysics Data System (ADS)

    Kinne, Stefan; Schulz, Michael; Griesfeller, Jan

    Properties of aerosol retrievals from space are difficult. Even data from dedicated satellite sensors face contaminations which limit the accuracy of aerosol retrieval products. Issues are the identification of complete cloud-free scenes, the need to assume aerosol compositional features in an underdetermined solution space and the requirement to characterize the background at high accuracy. Usually the development of aerosol is a slow process, requiring continuous feedback from evaluations. To demonstrate maturity, these evaluations need to cover different regions and seasons and many different aerosol properties, because aerosol composition is quite diverse and highly variable in space and time, as atmospheric aerosol lifetimes are only a few days. Three years ago the ESA Climate Change Initiative started to support aerosol retrieval efforts in order to develop aerosol retrieval products for the climate community from underutilized ESA satellite sensors. The initial focus was on retrievals of AOD (a measure for the atmospheric column amount) and of Angstrom (a proxy for aerosol size) from the ATSR and MERIS sensors on ENVISAT. The goal was to offer retrieval products that are comparable or better in accuracy than commonly used NASA products of MODIS or MISR. Fortunately, accurate reference data of ground based sun-/sky-photometry networks exist. Thus, retrieval assessments could and were conducted independently by different evaluation groups. Here, results of these evaluations for the year 2008 are summarized. The capability of these newly developed retrievals is analyzed and quantified in scores. These scores allowed a ranking of competing efforts and also allow skill comparisons of these new retrievals against existing and commonly used retrievals.

  1. MASTER-SAAO: bright PSN in PGC600519 and 2 OTs

    NASA Astrophysics Data System (ADS)

    Pogrosheva, T.; Balanutsa, P.; Lipunov, V.; Buckley, D.; Gorbovskoy, E.; Tiurina, N.; Gress, O.; Shumkov, V.; Kuznetsov, A.; Kornilov, V.; Chazov, V.; Vladimirov, V.; Vlasenko, D.; Potter, S.

    2016-10-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 10h 54m 40.86s , -39d 13m 19s.0 on 2016-10-08 02:56:46.019UT with . This PSN is in 2.9"E,7"N from the center of PGC600519 and is seen on 8 images.

  2. MASTER: bright OT discovered during Fermi trigger 512353690/GRB170328A inspection

    NASA Astrophysics Data System (ADS)

    Gorbovskoy, E.; Lipunov, V.; Buckley, D.; Rebolo, R.; Serra-Ricart, M.; Gress, O.; Tiurina, N.; Balanutsa, P.; Kornilov, V.; Vladimirov, V.

    2017-03-01

    MASTER-SAAO auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L ) discovered OT source at (RA, Dec) = 18h 45m 46.55s -35d 28m 47.6s on 2017-03-28.06645 UT during Fermi trigger 512353690(GRB170328A) inspection https://gcn.gsfc.nasa.gov/other/512353690.fermi (trigger time is 17/03/28 00:28:05.53UT).

  3. A simulation study of the ensemble-based data assimilation of satellite-borne lidar aerosol observations

    NASA Astrophysics Data System (ADS)

    Sekiyama, T. T.; Tanaka, T. Y.; Miyoshi, T.

    2012-07-01

    A four-dimensional ensemble-based data assimilation system was assessed by observing system simulation experiments (OSSEs), in which the CALIPSO satellite was emulated via simulated satellite-borne lidar aerosol observations. Its performance over athree-month period was validated according to the Method for Object-based Diagnostic Evaluation (MODE), using aerosol optical thickness (AOT) distributions in East Asia as the objects of analysis. Consequently, this data assimilation system demonstrated the ability to produce better analyses of sulfate and dust aerosols in comparison to a free-running simulation model. For example, the mean centroid distance (from the truth) over a three-month collection period of aerosol plumes was improved from 2.15 grids (≈ 600 km) to 1.45 grids (≈ 400 km) for sulfate aerosols and from 2.59 grids (≈ 750 km) to 1.14 grids (≈ 330 km) for dust aerosols; the mean area ratio (to the truth) over a three-month collection period of aerosol plumes was improved from 0.49 to 0.76 for sulfate aerosols and from 0.51 to 0.72 for dust aerosols. The satellite-borne lidar data assimilation successfully improved the aerosol plume analysis and the dust emission estimation in the OSSEs. These results present great possibilities for the beneficial use of lidar data, whose distribution is vertically/temporally dense but horizontally sparse, when coupled with a four-dimensional data assimilation system. In addition, sensitivity tests were conducted, and their results indicated that the degree of freedom to control the aerosol variables was probably limited in the data assimilation because the meteorological field in the system was constrained to weather reanalysis using Newtonian relaxation. Further improvements to the aerosol analysis can be performed through the simultaneous assimilation of aerosol observations with meteorological observations. The OSSE results strongly suggest that the use of real CALIPSO data will have a beneficial effect on

  4. 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).

  5. 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...

  6. 12 CFR 502.29 - How does OTS determine the condition component for a savings and loan holding company?

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 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...

  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. Simulation of Aerosols and Chemistry with a Unified Global Model

    NASA Technical Reports Server (NTRS)

    Chin, Mian

    2004-01-01

    This project is to continue the development of the global simulation capabilities of tropospheric and stratospheric chemistry and aerosols in a unified global model. This is a part of our overall investigation of aerosol-chemistry-climate interaction. In the past year, we have enabled the tropospheric chemistry simulations based on the GEOS-CHEM model, and added stratospheric chemical reactions into the GEOS-CHEM such that a globally unified troposphere-stratosphere chemistry and transport can be simulated consistently without any simplifications. The tropospheric chemical mechanism in the GEOS-CHEM includes 80 species and 150 reactions. 24 tracers are transported, including O3, NOx, total nitrogen (NOy), H2O2, CO, and several types of hydrocarbon. The chemical solver used in the GEOS-CHEM model is a highly accurate sparse-matrix vectorized Gear solver (SMVGEAR). The stratospheric chemical mechanism includes an additional approximately 100 reactions and photolysis processes. Because of the large number of total chemical reactions and photolysis processes and very different photochemical regimes involved in the unified simulation, the model demands significant computer resources that are currently not practical. Therefore, several improvements will be taken, such as massive parallelization, code optimization, or selecting a faster solver. We have also continued aerosol simulation (including sulfate, dust, black carbon, organic carbon, and sea-salt) in the global model to cover most of year 2002. These results have been made available to many groups worldwide and accessible from the website http://code916.gsfc.nasa.gov/People/Chin/aot.html.

  9. Determination of kinetic and thermochemical parameters of a substitution reaction at a square-planar palladium(II) complex in water/AOT/n-heptane microemulsions by flow microcalorimetry

    SciTech Connect

    Liveri, M.L.T.; Liveri, V.T.

    1995-12-01

    The substitution reaction [Pd(bipy)(e)]{sup 2+} + en {yields} [Pd(en){sub 2}]{sup 2+} + bipy (where bipy = 2,2{prime}-bipyridine and en=ethylenediamine) has been studied in water and water/AOT/n-heptane microemulsions at various values of the molar ratio R (R=[water]/[AOT]) by flow microcalorimetry. From calorimetric data, molar enthalpies of reaction and rate constants were obtained. These quantities indicate that, by increasing R, the reaction becomes less exothermic and its rate constant decreases, trending to the value observed in water. These features can be reasonably rationalized in terms of the peculiar solvation state of reactants inside the AOT reversed micelles and/or the peculiar physicochemical properties of micellar core.

  10. Long Noncoding RNA-Sox2OT Knockdown Alleviates Diabetes Mellitus-Induced Retinal Ganglion Cell (RGC) injury.

    PubMed

    Li, Chao-Peng; Wang, Shu-Hong; Wang, Wen-Qi; Song, Shu-Guang; Liu, Xiu-Ming

    2017-03-01

    Retinal ganglion cell (RGC) injury is one of the important pathological features of diabetes-induced retinal neurodegeneration. Increasing attention has been paid to find strategies for protecting against RGC injury. Long noncoding RNAs (lncRNAs) have emerged as the key regulators of many cell functions. Here, we show that Sox2OT expression is significantly down-regulated in the retinas of STZ-induced diabetic mice and in the RGCs upon high glucose or oxidative stress. SOX2OT knockdown protects RGCs against high glucose-induced injury in vitro. Moreover, Sox2OT knockdown plays a neuroprotective role in diabetes-related retinal neurodegeneration in vivo. Sox2OT knockdown could regulate oxidative stress response in RGCs and diabetic mouse retinas. Sox2OT knockdown plays an anti-oxidative role via regulating NRF2/HO-1 signaling activity. Taken together, Sox2OT knockdown may be a therapeutic strategy for the prevention and treatment of diabetes-induced retinal neurodegeneration.

  11. Gene expression profiles of prohibitin in testes of Octopus tankahkeei (ot-phb) revealing its possible role during spermiogenesis.

    PubMed

    Mao, Hai-Tao; Wang, Da-Hui; Lan, Zhou; Zhou, Hong; Yang, Wan-Xi

    2012-05-01

    Prohibitin is essential for intracellular homeostasis and stabilization of mitochondrial respiratory chain complexes. To explore its functions during spermiogenesis of Octopus tankahkeei (O. tankahkeei), we have cloned and sequenced the cDNA of this mammalian PHB homologue (termed ot-PHB) from the testes of O. tankahkeei. The 1165 bp ot-phb cDNA contains a 100 bp 5' UTR, a 882 bp open reading frame and a 183 bp 3' UTR. The putative ot-PHB protein owns a transmembrane domain from 6 to 31 amino acid (aa) and a putative PHB domain from 26 to 178 aa. Protein alignment demonstrated that ot-PHB had 73.3, 73.6, 74.0, 75.1, and 45.4% identity with its homologues in Homo sapiens, Mus muculus, Danio rerio, Xenopus tropicalis and Trypanosoma brucei, respectively. Tissue distribution profile analysis revealed its presence in all the tissues examined. In situ hybridization in spermiogenic cells demonstrated that ot-phb was expressed moderately at the beginning of the spermiogenesis. The abundance of transcripts increased in intermediate spermatids and in drastically remodeling final spermatids. In mature spermatozoa, the residuary transcripts concentrated around the chondriosomal mantle where mitochondria assemble around. In summary, the expression of ot-phb during spermiogenesis implicates a potential function of this protein during mitochondrial ubiquitination. It is the first time to implicate the role of prohibitin in cephalopod spermiogenesis.

  12. Corrosion behaviour of Nitinol alloy coated with alkylsilanes and polypyrrole.

    PubMed

    Flamini, D O; Saidman, S B

    2014-11-01

    Nitinol (equiatomic Ni and Ti alloy (NiTi)) substrate was modified using a coating system formed by a self-assembled film of alkylsilane compounds (propyltrichlorosilane (C3H7SiCl3) or octadecyltrichlorosilane (C18H37SiCl3)) and polypyrrole (PPy) doped with sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol OT or AOT). The combination of alkylsilanes and the presence of a voluminous molecule like AOT entrapped into the PPy films improve the pitting corrosion resistance of the substrate in chloride solution. The best performance was achieved with the longest alkylsilane chains, where the PPy film remains adhered to the underlying coating after a pitting corrosion test.

  13. Chemical, Physical and Optical Properties of Saharan Dust Aerosols at a Marine Site in Puerto Rico

    NASA Astrophysics Data System (ADS)

    Ortiz Montalvo, D. L.; Mayol Bracero, O. L.; Morales, F.; Sheridan, P.; Ogren, J. A.

    2005-12-01

    Atmospheric dust particles blown from the Sahara across the Atlantic into the Caribbean have an impact on its climate and public health. These particles may play a significant role in radiative forcing, affecting the extinction of solar radiation and thus having an influence on climate. About half of the dust that travels from Africa contains particles that are small enough to inhale. Human breathe them into the respiratory system and they settle in the lungs causing respiratory problems. To have a better understanding of these effects, information is needed on the properties of these aerosols. As part of this study, chemical, physical and optical characterization is being performed on aerosol samples collected at a marine site on the northeastern tip of Puerto Rico (Cabezas de San Juan, Fajardo), during periods with and without Saharan incursions. Stacked-filter units (SFU) are used to collect particles with diameters smaller than 1.7 μm, using Nuclepore, quartz and Teflon filters. These filter samples are analyzed to obtain the chemical composition of the particles. Initially we are focusing on the carbonaceous fraction (elemental and organic carbon, EC, and OC) of the aerosol using thermal/optical analysis. Online measurements of total particle number concentrations and aerosol light scattering coefficients are performed using a condensation particle counter and an integrating nephelometer, respectively. In addition, a sunphotometer, part of AERONET (http://aeronet.gsfc.nasa.gov/), is used to obtain the aerosol optical thickness (AOT). Preliminary results include only samples collected from air masses under the influence of Saharan dust, as signified by AOT satellite images from MODIS and the results from the air masses backward trajectories calculated with the NOAA HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) model. In terms of the chemical composition, EC concentrations were at low-to-undetectable levels, indicating that OC concentrations

  14. Structural evolution within the one-phase region of a three-component microemulsion system: Water-n-decane-sodium-bis-ethylhexylsulfosuccinate (AOT)

    NASA Astrophysics Data System (ADS)

    Chen, S.-H.; Chang, S.-L.; Strey, R.

    1990-08-01

    The continuous inversion from a water-in-oil (w/o) microemulsion at low temperatures to an oil-in-water (o/w) microemulsion at higher temperatures within the one-phase channel of water (0.6% NaCl)-n-decane-AOT microemulsion system is investigated by small angle neutron scattering (SANS). At constant AOT (surfactant) weight fraction γ of 12%, the structural evolution as a function of temperature takes place in different forms as the oil-to-water weight fraction α is varied from 15 to 90 %. At low o-w weight fractions (α=15 and 20 %) the microemulsions transform from a water-internal, oil-continuous structure at lower temperatures to an oil-internal, water-continuous droplet structure at higher temperatures jumping across an intermediate region of a lamellar phase (Lα). However, at higher o-w weight fractions (α=80 and 90 %) the evolution goes through a stage of percolation of the water droplets first into extended water clusters, then the structural inversion takes place probably through a transition of these water clusters into an entangled tubular structure. At equal oil-to-water volume ration (α=40%), the structure can be described as bicontinuous at both low and high temperatures. In this case we are able to extract two lengths characterizing the structure from SANS data using different models for the scattering length density fluctuation correlation function of a bicontinuous microemulsion.

  15. Chemical and optical properties of atmospheric aerosols in Phimai, Thailand by intensive surface measurements and satellite data analysis

    NASA Astrophysics Data System (ADS)

    Tsuruta, H.; Thana, B.; Takamura, T.; Hashimoto, M.; Yabuki, M.; Oikawa, E.; Nakajima, T.

    2013-12-01

    Atmospheric aerosols were measured at the Observatory of Atmospheric Research, in Phimai, Thailand, a key station of SKYNET, during 2006-2008. In the surface measurement, mass concentrations and major chemical components in fine and coarse aerosols were analyzed, and the optical properties such as AOT and SSA were measured by skyradiometer. Analysis of MODIS and CALIPSO satellite data was made for wild fire activities and aerosol distribution, respectively. In this paper, the following topics are summarized. The surface wind pattern in dry season was divided into the three periods as follows; D1 (Oct.-Nov.) with northeasterly monsoon, D3 (middle March-April) with southerly wind, and D2 (Dec.-early March) with a transit stage between D1 and D3. Wet season in southwesterly monsoon was from May to September. The concentration ratio of BC/nss-SO4 showed that the dominant PM2.5 aerosols in D1 were due to long-range transport of air pollutants emitted from urban/industrial area of east Asia. In contrast, most of aerosols in D3 were derived from biomass burning in Indochina, because the activity of biomass burning was highest in the latter D2 and early D3 period, by the analysis of the fire database in MODIS and of BC/nss-SO4. The mass concentration in PM2.5 showed a clear seasonal variation with the maximum in D2. On the contrary, AOT showed the maximum in D3, and which could be attributed to an increase in the vertical thickness of high aerosol concentration in the boundary layer by the CALIOP data analysis. Dust particles in D1 were directly transported from east Asia, and re-suspension of soil dusts was dominant in D2 because the surface soil became dry. In D3, soil dusts were re-suspended with the thermal plume caused by biomass burning. In contrast, high dust particles measured in the wet season was due to long range transport of dust aerosols from western desert area by the CALIOP data analysis.

  16. Science verification of operational aerosol and cloud products for TROPOMI on Sentinel-5 precursor

    NASA Astrophysics Data System (ADS)

    Lelli, Luca; Gimeno-Garcia, Sebastian; Sanders, Abram; Sneep, Maarten; Rozanov, Vladimir V.; Kokhanvosky, Alexander A.; Loyola, Diego; Burrows, John P.

    2016-04-01

    With the approaching launch of the Sentinel-5 precursor (S-5P) satellite, scheduled by mid 2016, one preparatory task of the L2 working group (composed by the Institute of Environmental Physics IUP Bremen, the Royal Netherlands Meteorological Institute KNMI De Bilt, and the German Aerospace Center DLR Oberpfaffenhofen) has been the assessment of biases among aerosol and cloud products, that are going to be inferred by the respective algorithms from measurements of the platform's payload TROPOspheric Monitoring Instrument (TROPOMI). The instrument will measure terrestrial radiance with varying moderate spectral resolutions from the ultraviolet throughout the shortwave infrared. Specifically, all the operational and verification algorithms involved in this comparison exploit the sensitivity of molecular oxygen absorption (the A-band, 755-775 nm, with a resolution of 0.54 nm) to changes in optical and geometrical parameters of tropospheric scattering layers. Therefore, aerosol layer height (ALH) and thickness (AOT), cloud top height (CTH), thickness (COT) and albedo (CA) are the targeted properties. First, the verification of these properties has been accomplished upon synchronisation of the respective forward radiative transfer models for a variety of atmospheric scenarios. Then, biases against independent techniques have been evaluated with real measurements of selected GOME-2 orbits. Global seasonal bias assessment has been carried out for CTH, CA and COT, whereas the verification of ALH and AOT is based on the analysis of the ash plume emitted by the icelandic volcanic eruption Eyjafjallajökull in May 2010 and selected dust scenes off the Saharan west coast sensed by SCIAMACHY in year 2009.

  17. Overview of Aerosol Distribution

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram

    2005-01-01

    Our knowledge of atmospheric aerosols (smoke, pollution, dust or sea salt particles, small enough to be suspended in the air), their evolution, composition, variability in space and time and interaction with clouds and precipitation is still lacking despite decades of research. Understanding the global aerosol system is fundamental for progress in climate change and hydrological cycle research. While a single instrument was used to demonstrate 50 years ago that the global CO2 levels are rising, posing threat of global warming, we need an array of satellites and field measurements coupled with chemical transport models to understand the global aerosol system. This complexity of the aerosol problem results from their short lifetime (1 week) and variable chemical composition. A new generation of satellites provides exciting opportunities to measure the global distribution of aerosols, distinguishing natural from anthropogenic aerosol and measuring their interaction with clouds and climate. I shall discuss these topics and application of the data to air quality monitoring.

  18. Tropical Atlantic Dust and Smoke Aerosol Variations 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.

    2013-01-01

    In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) fine mode fraction and Multi-angle Imaging SpectroRadiometer (MISR) nonspherical fraction data are used to derive dust and smoke aerosol optical thickness (T(sub dust) and T(sub smoke)) over the tropical Atlantic in a complementary way: due to its wider swath, MODIS has 3-4 times greater sampling than MISR, but MISR dust discrimination is based on particle shape retrievals, whereas an empirical scheme is used for MODIS. MODIS and MISR show very similar dust and smoke winter climatologies. T(sub dust) is the dominant aerosol component over the tropical Atlantic, accounting for 40-70 percent of the total aerosol optical thickness (AOT), whereas T(sub smoke) is significantly smaller than T(sub dust). The consistency and high correlation between these climatologies and their daily variations lends confidence to their use for investigating the relative dust and smoke contributions to the total AOT variation associated with the Madden-Julian Oscillation (MJO). The temporal evolution and spatial patterns of the tdus anomalies associated with the MJO are consistent between MODIS and MISR: the magnitude of MJO-realted T(sub dust) anomalies is comparable to or even larger than that of the total T, while the T(sub smoke) anomaly represents about 15 percent compared to the total, which is quite different from their relative magnitudes to the total T on the climatological time scale. This suggests that dust and smoke are not influenced by the MJO in the same way. Based on correlation analysis, dust is strongly influenced by the MJO-modulated trade wind and precipitation anomalies, and can last as long as one MJO phase, whereas smoke is less affected.

  19. Aerosol, radiation, and climate

    NASA Technical Reports Server (NTRS)

    Pollack, J. B.

    1983-01-01

    Airborne, spaceborne, and ground-based measurements are used to study the radiative and climatic effects of aerosols. The data, which are modelled with a hierarchy of radiation and climate models, and their implications are summarized. Consideration is given to volcanic aerosols, polar stratospheric clouds, and the Arctic haze. It is shown that several types of aerosols (volcanic particles and the Arctic haze) cause significant alterations to the radiation budget of the regions where they are located.

  20. The Long-Term (1964-2014) Variability of Aerosol Optical Thickness and its Impact on Solar Irradiance Based on the Data Taken at Belsk, Poland

    NASA Astrophysics Data System (ADS)

    Posyniak, Michał; Szkop, Artur; Pietruczuk, Aleksander; Podgórski, Jerzy; Krzyścin, Janusz

    2016-10-01

    Measurements of the Linke turbidity factor (LTF) were performed at Belsk (20.78°E, 51.83°N), Poland, since 1964. This data is used to retrieve broadband aerosol optical thickness normalized to the air mass equal to 2 (BAOT2). A linear analysis of the BAOT2 changes reveals an upward trend of 0.023±0.017(2 σ) in the 1964-1975 period, a downward trend of-0.051±0.017(2 σ) in the 1976-1991 period, and afterwards a statistically insignificant trend of-0.009 ± 0.014(2 σ). Such pattern may be related to the economic changes in Poland (changing emissions and environmental policies). The elevated BAOT2 values, excluded from the trend, are found in 1984 and 1992 due to the volcanic eruptions of El Chichon and Mt. Pinatubo, respectively. Past AOT values at 340 and 500 nm are reconstructed using a linear relationship found between AOT and BAOT2. The reconstructed data is used by the radiative transfer models to estimate a response of the total solar and erythemal radiation to the changes in the atmospheric aerosols at Belsk.

  1. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1997-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size resolved aerosol microphysics and chemistry. Both profiles included pollution haze layer from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core.

  2. Structural insight into dephosphorylation by trehalose 6-phosphate phosphatase (OtsB2) from Mycobacterium tuberculosis.

    PubMed

    Shan, Shan; Min, Haowei; Liu, Ting; Jiang, Dunquan; Rao, Zihe

    2016-12-01

    Trehalose serves as a key structural component in the cell wall of Mycobacterium tuberculosis. M. tuberculosis trehalose-6-phosphate phosphatase (MtbTPP), an essential enzyme in the trehalose biosynthesis OtsAB pathway, catalyzes the dephosphorylation of trehalose-6-phosphate (trehalose-6-P) to generate trehalose, and plays a critical role in M. tuberculosis survival-associated cell wall formation and permeability. Therefore, MtbTPP (OtsB2) is considered a promising potential target for discovery of antimicrobial drugs. However, the absence of structural information of MtbTPP restrains our understanding of its underlying catalytic mechanism. Here, we report the high-resolution crystal structures of apo active MtbTPP and its trehalose-6-P bound complex. The apo structure presents a canonical haloacid dehalogenase superfamily structural fold plus an extra N-terminal domain. The catalytic center is located in a positively charged cleft between the hydrolase domain and the cap domain, demonstrating a highly conserved substrate binding pocket. The role of residues interacting with the substrate in catalysis were probed by site-directed mutagenesis. Asp147, Asp149, Asp330, and Asp331 were found to be pivotal for the enzymatic activity of MtbTPP. The MtbTPP structures reported here provide insight into a key step in the biosynthesis of trehalose, which would facilitate future development of anti-TB therapeutics.-Shan, S., Min, H., Liu, T., Jiang, D., Rao, Z. Structural insight into dephosphorylation by trehalose 6-phosphate phosphatase (OtsB2) from Mycobacterium tuberculosis.

  3. Spectroscopic classification of PSN J13144705+5405055 (= MASTER OT J131447.05+540505.5)

    NASA Astrophysics Data System (ADS)

    Vanni, S.; Pastorello, A.; Benetti, S.; Cappellaro, E.; Ochner, P.; Tomasella, L.; Turatto, M.

    2012-11-01

    We report that optical spectroscopy (range 340-820 nm; resolution 1.3 nm) obtained on Nov. 8.18 UT with the Asiago 1.82-m Copernico Telescope (+ AFOSC), shows that PSN J13144705+5405055 (= MASTER OT J131447.05+540505.5) is a type-Ia SN at a redshift z~0.033 (Sloan Digital Sky Survey Data Release 3). The best match was found with type-Ia SN 2002bo (Benetti et al. 2004, MNRAS, 348, 261) about 3-4 weeks after the B band maximum light.

  4. 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.

  5. Complete Genome Sequence of the Larvicidal Bacterium Lysinibacillus sphaericus Strain OT4b.25

    PubMed Central

    Rey, Andrés; Silva-Quintero, Laura

    2016-01-01

    Lysinibacillus sphaericus OT4b.25 is a native Colombian strain isolated from coleopteran larvae in an oak forest near Bogotá D.C.; this strain has shown high levels of pathogenic activity against Culex quinquefasciatus larvae in laboratory assays compared to that of other members of the same species. Using Pacific Biosciences sequencing technology, we propose a chromosomal contig of 4,665,775 bp that, according to comparative analysis, is highly similar to that of reference strain L. sphaericus C3-41. PMID:27151786

  6. Physical and Radiative Properties of Aerosol Particles in the Caribbean: Influence of African Dust and Soufriere Volcanic Ash

    NASA Astrophysics Data System (ADS)

    Villanueva-Birriel, C. M.; Mayol-Bracero, O. L.; Sheridan, P.; Ogren, J. A.

    2007-12-01

    Atmospheric particles such as dust and volcanic ash have the potential of influencing the earth's radiative budget directly by scattering or absorbing solar radiation in the atmosphere and indirectly by affecting cloud condensation nuclei (CCN) concentrations and, therefore, cloud albedo. The radiatively-important properties of atmospheric particles are determined at the most fundamental level by their chemical composition and size distributions; therefore, the importance of studying the chemical, physical, and optical aerosol properties. Over the summer months, the island of Puerto Rico receives African dust incursions that reduce visibility and have an impact on public health, ecosystem, and climate. Visibility is also negatively affected when the island receives south-east winds and the Soufriere volcano (Montserrat Island) has been active. Here we present preliminary results of measurements performed during 2006 and 2007 at Cape San Juan, a ground-based station located at the northeastern tip of Puerto Rico. The cases investigated showed three possible types of air masses: clean (C), with African Dust (AD), and with volcanic ash (VA) from the Soufriere. We used a condensation particle counter to determine the particle number concentration, a sunphotometer (part of the AERONET) to determine volume size distributions and aerosol optical thickness (AOT), a 3-wavelength nephelometer to determine the scattering coefficients, and a 3-wavelength particle/soot absorption photometer (PSAP) for the absorption coefficients. The particle number concentrations were higher for AD and VA periods (up to about 700 cm-3 on average for both cases) in contrast to ~400 cm-3 for the C period. Volume size distributions showed bimodal distributions for the three cases with a greater influence of the coarse fraction for the C and VA periods and an increase in the fine particles for the AD period. The total scattering coefficient showed higher values for the AD (30 Mm-1) and the VA (26

  7. Direct Aerosol Forcing Uncertainty

    DOE Data Explorer

    Mccomiskey, Allison

    2008-01-15

    Understanding sources of uncertainty in aerosol direct radiative forcing (DRF), the difference in a given radiative flux component with and without aerosol, is essential to quantifying changes in Earth's radiation budget. We examine the uncertainty in DRF due to measurement uncertainty in the quantities on which it depends: aerosol optical depth, single scattering albedo, asymmetry parameter, solar geometry, and surface albedo. Direct radiative forcing at the top of the atmosphere and at the surface as well as sensitivities, the changes in DRF in response to unit changes in individual aerosol or surface properties, are calculated at three locations representing distinct aerosol types and radiative environments. The uncertainty in DRF associated with a given property is computed as the product of the sensitivity and typical measurement uncertainty in the respective aerosol or surface property. Sensitivity and uncertainty values permit estimation of total uncertainty in calculated DRF and identification of properties that most limit accuracy in estimating forcing. Total uncertainties in modeled local diurnally averaged forcing range from 0.2 to 1.3 W m-2 (42 to 20%) depending on location (from tropical to polar sites), solar zenith angle, surface reflectance, aerosol type, and aerosol optical depth. The largest contributor to total uncertainty in DRF is usually single scattering albedo; however decreasing measurement uncertainties for any property would increase accuracy in DRF. Comparison of two radiative transfer models suggests the contribution of modeling error is small compared to the total uncertainty although comparable to uncertainty arising from some individual properties.

  8. Global Aerosol Observations

    Atmospheric Science Data Center

    2013-04-19

    ... atmosphere, directly influencing global climate and human health. Ground-based networks that accurately measure column aerosol amount and ... being used to improve Air Quality Models and for regional health studies. To assess the human-health impact of chronic aerosol exposure, ...

  9. Portable Aerosol Contaminant Extractor

    DOEpatents

    Carlson, Duane C.; DeGange, John J.; Cable-Dunlap, Paula

    2005-11-15

    A compact, portable, aerosol contaminant extractor having ionization and collection sections through which ambient air may be drawn at a nominal rate so that aerosol particles ionized in the ionization section may be collected on charged plate in the collection section, the charged plate being readily removed for analyses of the particles collected thereon.

  10. Ganges valley aerosol experiment.

    SciTech Connect

    Kotamarthi, V.R.; Satheesh, S.K.

    2011-08-01

    In June 2011, the Ganges Valley Aerosol Experiment (GVAX) began in the Ganges Valley region of India. The objective of this field campaign is to obtain measurements of clouds, precipitation, and complex aerosols to study their impact on cloud formation and monsoon activity in the region.

  11. Solar-energy-system performance evaluation: Honeywell OTS 44, Ocmulgee, Georgia

    NASA Technical Reports Server (NTRS)

    Mathur, A. K.; Pederson, S.

    1982-01-01

    The operation and technical performance of the solar operational test site (OTS 44) are described, based on data collected between April, 1981 and August, 1981. The following topics are discussed: system description, performance assessment, operating energy, energy savings, system maintenance, and conclusions. The solar energy system at OTS 44 is a hydronic heating and cooling system consisting of 5040 square feet of liquid cooled flat plate collectors; a 4000 gallon thermal storage tank; one 25 ton capacity organic Rankine cycle engine assisted water chillers; a forced draft cooling tower; and associated piping, pumps, valves, controls and heat rejection equipment. The solar system has eight basic modes of operation and several combination modes for providing space conditioning and hot water to the building. Data monitored during the 4 months of the operational test period found that the solar system collected 285 MMBtu of thermal energy of the total incident solar energy of 1040 MMBtu and provided 210 MMBtu for cooling and 10 MMBtu for heating and hot water. The net electrical energy saving due to the solar system was approximately 2600 kWh(e), and fossil energy saving was about 20 million Btu (MMBtu).

  12. DeSSpOt: an instrument for stellar spin orientation determination

    NASA Astrophysics Data System (ADS)

    Lesage, Anna-Lea; Schneide, Magnus; Wiedemann, Günter

    2012-09-01

    We designed and constructed a special instrument to enable the determination of the stellar's spin orientation. The Differential image rotator for Stellar Spin Orientation, DeSSpOt, allows the simultaneous observations of two anti-parallel orientations of the star on the spectrum. On a high resolution échelle spectrum, the stellar rotation causes a slight line tilt visible in the spatial direction which is comparable to a rotation curve. We developed a new method, which exploits the variations in these tilts, to estimate the absolute position angle of the rotation axis. The line tilt is retrieved by a spectroastrometric extraction of the spectrum. In order to validate the method, we observed spectroscopic binaries with known orbital parameters. The determination of the orbital position angle is equivalent to the determination of the stellar position angle, but is easier to to detect. DeSSpOt was successfully implemented on the high resolution Coudé spectrograph of the Thüringer Landessternwarte Tautenburg. The observations of Capella led to the determination of the orbital position angle. Our value of 37.2° is in agreement with the values previously found in the literature. As such we verified that both method and instrument are valid.

  13. Solar-energy-system performance evaluation: Honeywell OTS 44, Ocmulgee, Georgia

    NASA Astrophysics Data System (ADS)

    Mathur, A. K.; Pederson, S.

    1982-08-01

    The operation and technical performance of the solar operational test site (OTS 44) are described, based on data collected between April, 1981 and August, 1981. The following topics are discussed: system description, performance assessment, operating energy, energy savings, system maintenance, and conclusions. The solar energy system at OTS 44 is a hydronic heating and cooling system consisting of 5040 square feet of liquid cooled flat plate collectors; a 4000 gallon thermal storage tank; one 25 ton capacity organic Rankine cycle engine assisted water chillers; a forced draft cooling tower; and associated piping, pumps, valves, controls and heat rejection equipment. The solar system has eight basic modes of operation and several combination modes for providing space conditioning and hot water to the building. Data monitored during the 4 months of the operational test period found that the solar system collected 285 MMBtu of thermal energy of the total incident solar energy of 1040 MMBtu and provided 210 MMBtu for cooling and 10 MMBtu for heating and hot water. The net electrical energy saving due to the solar system was approximately 2600 kWh(e), and fossil energy saving was about 20 million Btu (MMBtu).

  14. Solar energy system performance evaluation - final report for Honeywell OTS 45, Salt River Project, Phoenix, Arizona

    SciTech Connect

    Mathur, A K

    1983-09-01

    This report describes the operation and technical performance of the Solar Operational Test Site (OTS 45) at Salt River Project in Phoenix, Arizona, based on the analysis of data collected between April 1981 and March 31, 1982. The following topics are discussed: system description, performance assessment, operating energy, energy savings, system maintenance, and conclusions. The solar energy system at OTS 45 is a hydronic heating and cooling system consisting of 8208 square feet of liquid-cooled flat-plate collectors; a 2500-gallon thermal storage tank; two 25-ton capacity organic Rankine-cycle-engine-assisted water chillers; a forced-draft cooling tower; and associated piping, pumps, valves, controls and heat rejection equipment. The solar system has eight basic modes of operation and several combination modes. The system operation is controlled automatically by a Honeywell-designed microprocessor-based control system, which also provides diagnostics. Based on the instrumented test data monitored and collected during the 8 months of the Operational Test Period, the solar system collected 1143 MMBtu of thermal energy of the total incident solar energy of 3440 MMBtu and provided 241 MMBtu for cooling and 64 MMBtu for heating. The projected net annual electrical energy savings due to the solar system was approximately 40,000 kWh(e).

  15. Solar energy system performance evaluation: Honeywell OTS 41, Shenandoah (Newman), Georgia

    NASA Astrophysics Data System (ADS)

    Mathur, A. K.; Pederson, S.

    1982-08-01

    The operation and technical performance of the Solar Operational Test Site (OTS 41) located at Shenandoah, Georgia, are described, based on the analysis of the data collected between January and August 1981. The following topics are discussed: system description, performance assessment, operating energy, energy savings, system maintenance, and conclusions. The solar energy system at OTS 41 is a hydronic heating and cooling system consisting of 702 square feet of liquid-cooled flat-plate collectors; a 1000-gallon thermal storage tank; a 3-ton capacity organic Rankine-cycle-engine-assisted air conditioner; a water-to-are heat exchanger for solar space heating; a finned-tube coil immersed in the storage tank to preheat water for a gas-fired hot water heater; and associated piping, pumps, valves, and controls. The solar system has six basic modes of operation and several combination modes. The system operation is controlled automatically by a Honeywell-designed microprocessor-based control system, which also provides diagnostics.

  16. Radiative Effects of Aerosols

    NASA Technical Reports Server (NTRS)

    Valero, Francisco P. J.

    1996-01-01

    During the Atlantic Stratocumulus Transition Experiment (ASTEX) in June 1992, two descents in cloud-free regions allowed comparison of the change in aerosol optical depth as determined by an onboard total-direct-diffuse radiometer (TDDR) to the change calculated from measured size-resolved aerosol microphysics and chemistry. Both profiles included a pollution haze from Europe but the second also included the effect of a Saharan dust layer above the haze. The separate contributions of supermicrometer (coarse) and submicrometer (fine) aerosol were determined and thermal analysis of the pollution haze indicated that the fine aerosol was composed primarily of a sulfate/water mixture with a refractory soot-like core. The soot core increased the calculated extinction by about 10% in the most polluted drier layer relative to a pure sulfate aerosol but had significantly less effect at higher humidities. A 3 km descent through a boundary layer air mass dominated by pollutant aerosol with relative humidities (RH) 10-77% yielded a close agreement between the measured and calculated aerosol optical depths (550 nm) of 0.160 (+/- 0.07) and 0. 157 (+/- 0.034) respectively. During descent the aerosol mass scattering coefficient per unit sulfate mass varied from about 5 to 16 m(exp 2)/g and primarily dependent upon ambient RH. However, the total scattering coefficient per total fine mass was far less variable at about 4+/- 0.7 m(exp 2)/g. A subsequent descent through a Saharan dust layer located above the pollution aerosol layer revealed that both layers contributed similarly to aerosol optical depth. The scattering per unit mass of the coarse aged dust was estimated at 1.1 +/- 0.2 m(exp 2)/g. The large difference (50%) in measured and calculated optical depth for the dust layer exceeded measurements.

  17. Role of Charge and Solvation in the Structure and Dynamics of Alanine-Rich Peptide AKA2 in AOT Reverse Micelles

    PubMed Central

    2015-01-01

    The propensity of peptides to form α-helices has been intensely studied using theory, computation, and experiment. Important model peptides for the study of the coil-to-helix transition have been alanine–lysine (AKA) peptides in which the lysine residues are placed on opposite sides of the helix avoiding charge repulsion while enhancing solubility. In this study, the effects of capped versus zwitterionic peptide termini on the secondary structure of alanine-rich peptides in reverse micelles are explored. The reverse micelles are found to undergo substantial shape fluctuations, a property observed in previous studies of AOT reverse micelles in the absence of solvated peptide. The peptides are observed to interact with water, as well as the AOT surfactant, including interactions between the nonpolar residues and the aliphatic surfactant tails. Computation of IR spectra for the amide I band of the peptide allows for direct comparison with experimental spectra. The results demonstrate that capped AKA2 peptides form more stable α helices than zwitterionic AKA2 peptides in reverse micelles. The rotational anisotropy decay of water is found to be distinctly different in the presence or absence of peptide within the reverse micelle, suggesting that the introduction of peptide significantly alters the number of free waters within the reverse micelle nanopool. However, neither the nature of the peptide termini (capped or charged) nor the degree of peptide helicity is found to significantly alter the balance of interactions between the peptides and the environment. Observed changes in the degree of helicity in AKA2 peptides in bulk solution and in reverse micelle environments result from changes in peptide confinement and hydration as well as direct nonpolar and polar interactions with the water–surfactant interface. PMID:25337983

  18. Genome sequence and description of the heavy metal tolerant bacterium Lysinibacillus sphaericus strain OT4b.31

    PubMed Central

    Peña-Montenegro, Tito David; Dussán, Jenny

    2013-01-01

    Lysinibacillus sphaericus strain OT4b.31 is a native Colombian strain having no larvicidal activity against Culex quinquefasciatus and is widely applied in the bioremediation of heavy-metal polluted environments. Strain OT4b.31 was placed between DNA homology groups III and IV. By gap-filling and alignment steps, we propose a 4,096,672 bp chromosomal scaffold. The whole genome (consisting of 4,856,302 bp long, 94 contigs and 4,846 predicted protein-coding sequences) revealed differences in comparison to the L. sphaericus C3-41 genome, such as syntenial relationships, prophages and putative mosquitocidal toxins. Sphaericolysin B354, the coleopteran toxin Sip1A and heavy metal resistance clusters from nik, ars, czc, cop, chr, czr and cad operons were identified. Lysinibacillus sphaericus OT4b.31 has applications not only in bioremediation efforts, but also in the biological control of agricultural pests. PMID:24501644

  19. Kcnq1ot1/Lit1 Noncoding RNA Mediates Transcriptional Silencing by Targeting to the Perinucleolar Region ▿ †

    PubMed Central

    Mohammad, Faizaan; Pandey, Radha Raman; Nagano, Takashi; Chakalova, Lyubomira; Mondal, Tanmoy; Fraser, Peter; Kanduri, Chandrasekhar

    2008-01-01

    The Kcnq1ot1 antisense noncoding RNA has been implicated in long-range bidirectional silencing, but the underlying mechanisms remain enigmatic. Here we characterize a domain at the 5′ end of the Kcnq1ot1 RNA that carries out transcriptional silencing of linked genes using an episomal vector system. The bidirectional silencing property of Kcnq1ot1 maps to a highly conserved repeat motif within the silencing domain, which directs transcriptional silencing by interaction with chromatin, resulting in histone H3 lysine 9 trimethylation. Intriguingly, the silencing domain is also required to target the episomal vector to the perinucleolar compartment during mid-S phase. Collectively, our data unfold a novel mechanism by which an antisense RNA mediates transcriptional gene silencing of chromosomal domains by targeting them to distinct nuclear compartments known to be rich in heterochromatic machinery. PMID:18299392

  20. REMOTE SENSING MEASUREMENTS OF AEROSOL OPTICAL THICKNESS AND CORRELATION WITH IN-SITU AIR QUALITY PARAMETERS DURING A SMOKE HAZE EPISODE IN SOUTHEAST ASIA

    NASA Astrophysics Data System (ADS)

    Chew, B.; Salinas Cortijo, S. V.; Liew, S.

    2009-12-01

    Transboundary smoke haze due to biomass burning is a major environmental problem in Southeast Asia which has not only affected air quality in the source region, but also in the surrounding countries. Air quality monitoring stations and meteorological stations can provide valuable information on the concentrations of criteria pollutants such as sulphur dioxide, nitrogen oxide, carbon monoxide, ozone and particulate mass (PM10) as well as health advisory to the general public during the haze episodes. Characteristics of aerosol particles in the smoke haze such as the aerosol optical thickness (AOT), aerosol size distribution and Angstrom exponent are also measured or retrieved by sun-tracking photometers, such as those deployed in the world-wide AErosol RObotic NETwork (AERONET). However, due to the limited spatial coverage by the air quality monitoring stations and AERONET sites, it is difficult to study and monitor the spatial and temporal variability of the smoke haze during a biomass burning episode, especially in areas without ground-based instrumentation. As such, we combine the standard in-situ measurements of PM10 by air quality monitoring stations with the remote sensing imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA's Terra and Aqua satellites. The columnar AOT is first derived from the MODIS images for regions where PM10 measurements are available. Empirical correlations between AOT and PM10 measurements are then established for 50 sites in both Malaysia and Singapore during the smoke haze episode in 2006. When available, vertical feature information from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) is used to examine the validity of the correlations. Aloft transport of aerosols, which can weaken the correlations between AOT and PM10 measurements, is also identified by CALIPSO and taken into consideration for the analysis. With this integrated approach, we hope to enhance and

  1. Aqueous aerosol SOA formation: impact on aerosol physical properties.

    PubMed

    Woo, Joseph L; Kim, Derek D; Schwier, Allison N; Li, Ruizhi; McNeill, V Faye

    2013-01-01

    Organic chemistry in aerosol water has recently been recognized as a potentially important source of secondary organic aerosol (SOA) material. This SOA material may be surface-active, therefore potentially affecting aerosol heterogeneous activity, ice nucleation, and CCN activity. Aqueous aerosol chemistry has also been shown to be a potential source of light-absorbing products ("brown carbon"). We present results on the formation of secondary organic aerosol material in aerosol water and the associated changes in aerosol physical properties from GAMMA (Gas-Aerosol Model for Mechanism Analysis), a photochemical box model with coupled gas and detailed aqueous aerosol chemistry. The detailed aerosol composition output from GAMMA was coupled with two recently developed modules for predicting a) aerosol surface tension and b) the UV-Vis absorption spectrum of the aerosol, based on our previous laboratory observations. The simulation results suggest that the formation of oligomers and organic acids in bulk aerosol water is unlikely to perturb aerosol surface tension significantly. Isoprene-derived organosulfates are formed in high concentrations in acidic aerosols under low-NO(x) conditions, but more experimental data are needed before the potential impact of these species on aerosol surface tension may be evaluated. Adsorption of surfactants from the gas phase may further suppress aerosol surface tension. Light absorption by aqueous aerosol SOA material is driven by dark glyoxal chemistry and is highest under high-NO(x) conditions, at high relative humidity, in the early morning hours. The wavelength dependence of the predicted absorption spectra is comparable to field observations and the predicted mass absorption efficiencies suggest that aqueous aerosol chemistry can be a significant source of aerosol brown carbon under urban conditions.

  2. Sugars in Antarctic aerosol

    NASA Astrophysics Data System (ADS)

    Barbaro, Elena; Kirchgeorg, Torben; Zangrando, Roberta; Vecchiato, Marco; Piazza, Rossano; Barbante, Carlo; Gambaro, Andrea

    2015-10-01

    The processes and transformations occurring in the Antarctic aerosol during atmospheric transport were described using selected sugars as source tracers. Monosaccharides (arabinose, fructose, galactose, glucose, mannose, ribose, xylose), disaccharides (sucrose, lactose, maltose, lactulose), alcohol-sugars (erythritol, mannitol, ribitol, sorbitol, xylitol, maltitol, galactitol) and anhydrosugars (levoglucosan, mannosan and galactosan) were measured in the Antarctic aerosol collected during four different sampling campaigns. For quantification, a sensitive high-pressure anion exchange chromatography was coupled with a single quadrupole mass spectrometer. The method was validated, showing good accuracy and low method quantification limits. This study describes the first determination of sugars in the Antarctic aerosol. The total mean concentration of sugars in the aerosol collected at the "Mario Zucchelli" coastal station was 140 pg m-3; as for the aerosol collected over the Antarctic plateau during two consecutive sampling campaigns, the concentration amounted to 440 and 438 pg m-3. The study of particle-size distribution allowed us to identify the natural emission from spores or from sea-spray as the main sources of sugars in the coastal area. The enrichment of sugars in the fine fraction of the aerosol collected on the Antarctic plateau is due to the degradation of particles during long-range atmospheric transport. The composition of sugars in the coarse fraction was also investigated in the aerosol collected during the oceanographic cruise.

  3. Infrared spectroscopy of aerosols

    NASA Astrophysics Data System (ADS)

    Mentel, Th.; Sebald, H.

    2003-04-01

    In our large Aerosol Chamber at the FZ Jülich we apply HR FTIR absorption spectroscopy for the determination of trace gases. In the FTIR spectra we also observe broad absorptions of several 10 to a few 100 cm-1 widths that arise from species in the condensed aerosol phase: liquid H_2O, NO_3^-, SO_42-, HSO_4^-, or dicarboxylic acids. Moreover, the aerosol droplets caused extinctions over several 1000 cm-1 by IR scattering. This allows for in-situ observation of changes in the condensed aerosol phase e.g. on HNO_3 uptake, like the shift of the sulfate/bisulfate equilibrium or the growth by water condensation. The IR absorptions of the condensed aerosol phase provide useful extra information in process studies, if they can be quantified. Therefore the absorption cross section, respective, the absorption index which is the imaginary part of the complex refractive index is needed. We set up an aerosol flow tube in which IR spectroscopy on a 8 m light path and aerosol size distribution measurements in the range from 20 nm - 10 μm can be performed simultaneously. We measured sulfate aerosols at several relative humidities (dry, metastable, deliquescent). We will demonstrate an iterative procedure based on Mie calculations and Kramers Kronig transformation to retrieve the absorption index from the observed IR spectra and the corresponding size distribution (for dry ammonium sulfate). We will compare resulting absorption indices for aqueous sodium bisulfate aerosols at several relative humidties with thermodynamic model calculations for the Na^+/H^+/HSO_4^-/SO_42-/H_2O system.

  4. Aerosol characterizaton in El Paso-Juarez airshed using optical methods

    NASA Astrophysics Data System (ADS)

    Esparza, Angel Eduardo

    2011-12-01

    retrieve the size distribution of them. This method permits the assessment of aerosols in the ambient in-situ, without physically extracting them from their current state, as the filter technique does. The second objective was an analysis and comparison of the aerosol optical thickness (AOT) data between ground-based instruments and satellite data. In this project, the groundbased instruments are the Multi Filter Rotating Shadowband Radiometers (MFRSR) installed at UTEP and the nearest sun photometer facility, a NASA's Aerosol Robotic Network (AERONET), located at White Sands, New Mexico. The satellite data is provided by the NASA's Multi-angle Imaging Spectro-radiometer (MISR) instrument located in the Terra satellite. Finally, the third objective was to estimate ground particulate matter concentration of particles no greater than 2.5 mum in diameter (PM2.5) by using the MISR's satellite data. This objective was achieved by implementing an empirical mathematical model that includes measured data. In addition, this model addressed the geographic characteristics of the region as well as several factors such as season, relative humidity (RH) and the height of the planetary boundary layer (PBL).

  5. Entraining IDyOT: Timing in the Information Dynamics of Thinking.

    PubMed

    Forth, Jamie; Agres, Kat; Purver, Matthew; Wiggins, Geraint A

    2016-01-01

    We present a novel hypothetical account of entrainment in music and language, in context of the Information Dynamics of Thinking model, IDyOT. The extended model affords an alternative view of entrainment, and its companion term, pulse, from earlier accounts. The model is based on hierarchical, statistical prediction, modeling expectations of both what an event will be and when it will happen. As such, it constitutes a kind of predictive coding, with a particular novel hypothetical implementation. Here, we focus on the model's mechanism for predicting when a perceptual event will happen, given an existing sequence of past events, which may be musical or linguistic. We propose a range of tests to validate or falsify the model, at various different levels of abstraction, and argue that computational modeling in general, and this model in particular, can offer a means of providing limited but useful evidence for evolutionary hypotheses.

  6. Entraining IDyOT: Timing in the Information Dynamics of Thinking

    PubMed Central

    Forth, Jamie; Agres, Kat; Purver, Matthew; Wiggins, Geraint A.

    2016-01-01

    We present a novel hypothetical account of entrainment in music and language, in context of the Information Dynamics of Thinking model, IDyOT. The extended model affords an alternative view of entrainment, and its companion term, pulse, from earlier accounts. The model is based on hierarchical, statistical prediction, modeling expectations of both what an event will be and when it will happen. As such, it constitutes a kind of predictive coding, with a particular novel hypothetical implementation. Here, we focus on the model's mechanism for predicting when a perceptual event will happen, given an existing sequence of past events, which may be musical or linguistic. We propose a range of tests to validate or falsify the model, at various different levels of abstraction, and argue that computational modeling in general, and this model in particular, can offer a means of providing limited but useful evidence for evolutionary hypotheses. PMID:27803682

  7. How Surface Heterogeneity Affects Protein Adsorption: Annealing of OTS Patterns and Albumin Adsorption Kinetics*

    PubMed Central

    Hodgkinson, Gerald N.; Hlady, Vladimir

    2009-01-01

    Fluorescence microscopy and intensity histogram analysis techniques were used to monitor spatially-resolved albumin adsorption kinetics to model heterogeneous surfaces on sub-μm scales. Several distinct protein subpopulations were resolved, each represented by a normal distribution of adsorption densities on the adsorbent surface. Histogram analyses provided dynamic information of mean adsorption density, spread in adsorption density, and surface area coverage for each distinct protein subpopulation. A simple adsorption model is proposed in which individual protein binding events are predicted by the summation of multiple protein's surface sub-site interactions with different binding energy sub-sites on adsorbent surfaces. This model is predictive of the albumin adsorption on the patterns produced by one step μ-contact printing (μCP) of octadecyltrichlorosilane (OTS) on glass but fails to describe adsorption once the same patterns are altered by a thermal annealing step. PMID:19746205

  8. The Persistent Eruption of UGC 2773-OT: finally, a decade-long extragalactic Eta Carinae analogue

    NASA Astrophysics Data System (ADS)

    Smith, Nathan; Andrews, Jennifer E.; Mauerhan, Jon C.; Zheng, WeiKang; Filippenko, Alexei V.; Graham, Melissa L.; Milne, Peter

    2016-02-01

    While supernova (SN) impostors resemble the Great Eruption of η Carinae in the sense that their spectra show narrow H lines and they have typical peak absolute magnitudes of -13 to -14 mag, most extragalactic events observed so far are quite different from η Car in duration. Their bright phases typically last for ˜100 d or less, rather than persisting for several years. The transient object UGC 2773-OT (discovered in 2009) had a similar peak absolute magnitude to other SN impostors, but with a gradual 5-yr pre-discovery rise. In the ˜6 yr since discovery, it has faded very slowly (0.26 mag yr-1). Overall, we suggest that its decade-long eruption is so far the best-known analogue of η Car's 19th century eruption. We discuss extensive spectroscopy of the ongoing eruption. The spectra show interesting changes in velocity and line shape that we discuss in detail, including an asymmetric Hα emission line that we show is consistent with the ejection of a bipolar nebula that could be very much like the Homunculus of η Car. Moreover, changes in the line width, line profile, blue excess emission resembling that of Type IIn SNe, and the intensity of Hα suggest the presence of strong circumstellar interaction in the eruption at late times. This supports the hypothesis that the extended plateau of η Car's eruption may have been powered by shock interaction as well. One interesting difference compared to η Car, however, is that UGC 2773-OT so far does not exhibit the repeated brief spikes in luminosity that have been associated with binary periastron events.

  9. Solar energy system performance evaluation: final report for Honeywell OTS 41, Shenandoah (Newnan), Georgia

    SciTech Connect

    Mathur, A K; Pederson, S

    1982-08-01

    The operation and technical performance of the Solar Operational Test Site (OTS 41) located at Shenandoah, Georgia, are described, based on the analysis of data collected between January and August 1981. The following topics are discussed: system description, performance assessment, operating energy, energy savings, system maintenance, and conclusions. The solar energy system at OTS 41 is a hydronic heating and cooling system consisting of 702 square feet of liquid-cooled flat-plate collectors; a 1000-gallon thermal storage tank; a 3-ton capacity organic Rankine-cycle-engine-assisted air conditioner; a water-to-air heat exchanger for solar space heating; a finned-tube coil immersed in the storage tank to preheat water for a gas-fired hot water heater; and associated piping, pumps, valves, and controls. The solar system has six basic modes of operation and several combination modes. The system operation is controlled automatically by a Honeywell-designed microprocessor-based control system, which also provides diagnostics. Based on the instrumented test data monitored and collected during the 7 months of the Operational Test Period, the solar system collected 53 MMBtu of thermal energy of the total incident solar energy of 219 MMBtu and provided 11.4 MMBtu for cooling, 8.6 MMBtu for heating, and 8.1 MMBtu for domestic hot water. The projected net annual energy savings due to the solar system were approximately 50 MMBtu of fossil energy (49,300 cubic feet of natural gas) and a loss of 280 kWh(e) of electrical energy.

  10. 12 CFR 516.290 - What will happen if OTS does not approve or disapprove my application within two calendar years...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... disapprove my application within two calendar years after the filing date? 516.290 Section 516.290 Banks and... within two calendar years after the filing date? (a) Withdrawal. If OTS has not approved or denied your pending application within two calendar years after the filing date under § 516.45, OTS will notify...

  11. 12 CFR 516.290 - What will happen if OTS does not approve or disapprove my application within two calendar years...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... disapprove my application within two calendar years after the filing date? 516.290 Section 516.290 Banks and... within two calendar years after the filing date? (a) Withdrawal. If OTS has not approved or denied your pending application within two calendar years after the filing date under § 516.45, OTS will notify...

  12. 12 CFR 516.290 - What will happen if OTS does not approve or disapprove my application within two calendar years...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... disapprove my application within two calendar years after the filing date? 516.290 Section 516.290 Banks and... within two calendar years after the filing date? (a) Withdrawal. If OTS has not approved or denied your pending application within two calendar years after the filing date under § 516.45, OTS will notify...

  13. 12 CFR 516.290 - What will happen if OTS does not approve or disapprove my application within two calendar years...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... disapprove my application within two calendar years after the filing date? 516.290 Section 516.290 Banks and... within two calendar years after the filing date? (a) Withdrawal. If OTS has not approved or denied your pending application within two calendar years after the filing date under § 516.45, OTS will notify...

  14. 12 CFR 516.290 - What will happen if OTS does not approve or disapprove my application within two calendar years...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... disapprove my application within two calendar years after the filing date? 516.290 Section 516.290 Banks and... within two calendar years after the filing date? (a) Withdrawal. If OTS has not approved or denied your pending application within two calendar years after the filing date under § 516.45, OTS will notify...

  15. Volcanic Aerosol Radiative Properties

    NASA Technical Reports Server (NTRS)

    Lacis, Andrew

    2015-01-01

    Large sporadic volcanic eruptions inject large amounts of sulfur bearing gases into the stratosphere which then get photochemically converted to sulfuric acid aerosol droplets that exert a radiative cooling effect on the global climate system lasting for several years.

  16. Palaeoclimate: Aerosols and rainfall

    NASA Astrophysics Data System (ADS)

    Partin, Jud

    2015-03-01

    Instrumental records have hinted that aerosol emissions may be shifting rainfall over Central America southwards. A 450-year-long precipitation reconstruction indicates that this shift began shortly after the Industrial Revolution.

  17. Emergency Protection from Aerosols

    SciTech Connect

    Cristy, G.A.

    2001-11-13

    Expedient methods were developed that could be used by an average person, using only materials readily available, to protect himself and his family from injury by toxic (e.g., radioactive) aerosols. The most effective means of protection was the use of a household vacuum cleaner to maintain a small positive pressure on a closed house during passage of the aerosol cloud. Protection factors of 800 and above were achieved.

  18. Monodisperse aerosol generator

    DOEpatents

    Ortiz, Lawrence W.; Soderholm, Sidney C.

    1990-01-01

    An aerosol generator is described which is capable of producing a monodisperse aerosol within narrow limits utilizing an aqueous solution capable of providing a high population of seed nuclei and an organic solution having a low vapor pressure. The two solutions are cold nebulized, mixed, vaporized, and cooled. During cooling, particles of the organic vapor condense onto the excess seed nuclei, and grow to a uniform particle size.

  19. Spectroscopic Classification of AT2016axw (=MASTER OT J142718.40-014031.0 =PS16axi)

    NASA Astrophysics Data System (ADS)

    Blanchard, Peter; Berger, Edo; Bieryla, Allyson; Brzycki, Bryan; Cohn, Amy; Dillett, Sean; Feder-Staehle, Richard; Frostig, Danielle; Grell, Gabe; James, Nicholas; Johnson, April; Mahmood, Zahra; Merryman, Hunter; Peak, Barra; Sanders, Cecilia; Taylor, Anthony

    2016-03-01

    We obtained a low-resolution optical spectrum of AT2016axw (=MASTER OT J142718.40-014031.0 =PS16ayd; ATel #8791). Observations were carried out on 2016 March 16.4 UT using the FAST spectrograph mounted on the F.L. Whipple Observatory 1.5-m telescope.

  20. Genome sequence of Desulfosporosinus sp. OT, an acidophilic sulfate-reducing bacterium from copper mining waste in Norilsk, Northern Siberia.

    PubMed

    Abicht, Helge K; Mancini, Stefano; Karnachuk, Olga V; Solioz, Marc

    2011-11-01

    We have sequenced the genome of Desulfosporosinus sp. OT, a Gram-positive, acidophilic sulfate-reducing Firmicute isolated from copper tailing sediment in the Norilsk mining-smelting area in Northern Siberia, Russia. This represents the first sequenced genome of a Desulfosporosinus species. The genome has a size of 5.7 Mb and encodes 6,222 putative proteins.

  1. Correction to ATel 10150: New OT is PTSS-17jdx deteted on 2017-03-07.727524 UT

    NASA Astrophysics Data System (ADS)

    Li, Bin

    2017-03-01

    We report a correction to the time of detection of new OT PTSS-17jdx in ATel #10150. The time of detection is 2017-03-07.727524 UT but not 2017-02-07.727524 UT. More interesting information can be found on PTSS . We apologize for any confusion caused by this typo error.

  2. 12 CFR 502.26 - How does OTS calculate the semi-annual assessment for savings and loan holding companies?

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ...-site supervision of a noncomplex, low risk savings and loan holding company structure. OTS will... savings and loan holding companies: a component based on the risk or complexity of the savings and loan holding company's business, a component based on its organizational form, and a component based on...

  3. 75 FR 63107 - Alternatives to the Use of External Credit Ratings in the Regulations of the OTS

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-14

    ..., savings associations must consider the interest rate, credit, liquidity, price and other risks presented... subject only to moderate credit risk, and for whom expectations of default risk over the term of the... the levels and types of risks in its portfolio. As with the credit quality standard, OTS could...

  4. Purification, crystallization and preliminary crystallographic analysis of the biotin–protein ligase from Pyrococcus horikoshii OT3

    SciTech Connect

    Bagautdinov, Bagautdin; Kuroishi, Chizu; Sugahara, Mitsuaki; Kunishima, Naoki

    2005-02-01

    The biotin–protein ligase from P. horikoshii OT3 was overexpressed, purified, crystallized and cocrystallized with biotin, ADP and biotinyl-5′-AMP. The crystals belong to space group P2{sub 1} and diffract to beyond 1.6 Å resolution.

  5. Interaction between surfactants and colloidal latexes in nonpolar solvents studied using contrast-variation small-angle neutron scattering.

    PubMed

    Smith, Gregory N; Alexander, Shirin; Brown, Paul; Gillespie, David A J; Grillo, Isabelle; Heenan, Richard K; James, Craig; Kemp, Roger; Rogers, Sarah E; Eastoe, Julian

    2014-04-01

    The interaction between deuterium-labeled Aerosol OT surfactant (AOT-d34) and sterically stabilized poly(methyl methacrylate) (PMMA) latex particles dispersed in nonpolar solvents has been studied using contrast-variation small-angle neutron scattering (CV-SANS). The electrophoretic mobilities (μ) of the latexes have been measured by phase-analysis light scattering, indicating that μ is negative. Two analogues of the stabilizers for the particles have been studied as free polymers in the absence of PMMA latexes: poly(12-hydroxystearic acid) (PHSA) polyester and poly(methyl methacrylate)-graft-poly(12-hydroxystearic acid) (PMMA-graft-PHSA) stabilizer copolymer. The scattering from both PHSA in dodecane and PMMA-graft-PHSA in toluene is consistent with extended polymer chains in good solvents. In dodecane, PMMA-graft-PHSA forms polymer micelles, and SANS is consistent with ellipsoidal aggregates formed of around 50 polymer chains. CV-SANS measurements were performed by measuring SANS from systems of PHSA, PMMA-graft-PHSA, and PMMA latexes with 10 and 100 mM surfactant solutions of AOT-d34 in both polymer/particle and AOT contrast-matched solvent. No excess scattering above the polymer or surfactant was found for PHSA in dodecane or PMMA-graft-PHSA in dodecane and toluene. This indicates that AOT does not significantly interact with the free polymers. Excess scattering was observed for systems with AOT-d34 and PMMA latexes dispersed in particle contrast-matched dodecane, consistent with the penetration of AOT into the PMMA latexes. This indicates that AOT does not interact preferentially with the stabilizing layers but, rather, is present throughout the colloids. Previous research ( Langmuir 2010, 26, 6967-6976 ) suggests that AOT surfactant is located in the latex PHSA-stabilizer layer, but all the results in this study are consistent with AOT poorly interacting with alkyl-stabilizer polymers.

  6. RACORO aerosol data processing

    SciTech Connect

    Elisabeth Andrews

    2011-10-31

    The RACORO aerosol data (cloud condensation nuclei (CCN), condensation nuclei (CN) and aerosol size distributions) need further processing to be useful for model evaluation (e.g., GCM droplet nucleation parameterizations) and other investigations. These tasks include: (1) Identification and flagging of 'splash' contaminated Twin Otter aerosol data. (2) Calculation of actual supersaturation (SS) values in the two CCN columns flown on the Twin Otter. (3) Interpolation of CCN spectra from SGP and Twin Otter to 0.2% SS. (4) Process data for spatial variability studies. (5) Provide calculated light scattering from measured aerosol size distributions. Below we first briefly describe the measurements and then describe the results of several data processing tasks that which have been completed, paving the way for the scientific analyses for which the campaign was designed. The end result of this research will be several aerosol data sets which can be used to achieve some of the goals of the RACORO mission including the enhanced understanding of cloud-aerosol interactions and improved cloud simulations in climate models.

  7. Theileria sp. OT3 and other tick-borne pathogens in sheep and ticks in Italy: molecular characterization and phylogeny.

    PubMed

    Giangaspero, A; Marangi, M; Papini, R; Paoletti, B; Wijnveld, M; Jongejan, F

    2015-02-01

    PCR Reverse Line Blot (RLB) hybridization and sequencing were used to determine the dynamics of infection with tick-borne pathogens in one hundred apparently healthy sheep in Italy. Blood samples were tested once prior to the onset of the grazing season (June 2010) and once after the end of the grazing season (August 2010). Ticks collected from sheep and from the vegetation were also tested by PCR/RLB. Before grazing, 56% of the sheep harbored several tick-borne pathogens: Anaplasma ovis was the most prevalent (41%), followed by A. ovis co-infected with Theileria sp. OT3 (14%). After grazing, 87% of sheep were positive for A. ovis alone (41%), co-infected with Theileria sp. OT3 (8%) or co-infected with Babesia motasi (5%). Other sheep were infected with Anaplasma phagocytophilum alone (20%), co-infected with B. motasi (7%) or with Theileria sp. OT3 (5%) (p<0.001). After grazing, sheep were significantly more infected with tick-borne pathogens than before grazing. Ticks collected were all Haemaphysalis punctata (n-89) and 36% were positive for A. ovis, Ehrlichia ovina and A. ovis combined with A. phagocytophilum. Phylogenetic analysis including isolates from countries in the Mediterranean Basin show circulation of the same variants of Theileria sp. OT3, whereas two different geographical origins for the isolates of A. ovis and A. phagocytophilum were identified. This is the first report from Italy of Theileria sp. OT3 in sheep, whereas the detection of Ehrlichia ovina in ticks is worth noting, and the presence of A. phagocytophilum in sheep and in ticks poses a potential public health risk.

  8. Retrieval of dust storm aerosols using an integrated Neural Network model

    NASA Astrophysics Data System (ADS)

    Xiao, Fei; Wong, Man Sing; Lee, Kwon Ho; Campbell, James R.; Shea, Yu-kai

    2015-12-01

    Dust storms are known to have adverse effects on public health. Atmospheric dust loading is also one of the major uncertainties in global climatic modeling as it is known to have a significant impact on the radiation budget and atmospheric stability. This study develops an integrated model for dust storm detection and retrieval based on the combination of geostationary satellite images and forward trajectory model. The proposed model consists of three components: (i) a Neural Network (NN) model for near real-time detection of dust storms; (ii) a NN model for dust Aerosol Optical Thickness (AOT) retrieval; and (iii) the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model to analyze the transports of dust storms. These three components are combined using an event-driven active geo-processing workflow technique. The NN models were trained for the dust detection and validated using sunphotometer measurements from the AErosol RObotic NETwork (AERONET). The HYSPLIT model was applied in the regions with high probabilities of dust locations, and simulated the transport pathways of dust storms. This newly automated hybrid method can be used to give advance near real-time warning of dust storms, for both environmental authorities and public. The proposed methodology can be applied on early warning of adverse air quality conditions, and prediction of low visibility associated with dust storm events for port and airport authorities.

  9. Exploring the role of hydration and confinement in the aggregation of amyloidogenic peptides Aβ16−22 and Sup357−13 in AOT reverse micelles

    PubMed Central

    Martinez, Anna Victoria; Małolepsza, Edyta; Rivera, Eva; Lu, Qing; Straub, John E.

    2014-01-01

    Knowledge of how intermolecular interactions of amyloid-forming proteins cause protein aggregation and how those interactions are affected by sequence and solution conditions is essential to our understanding of the onset of many degenerative diseases. Of particular interest is the aggregation of the amyloid-β (Aβ) peptide, linked to Alzheimer's disease, and the aggregation of the Sup35 yeast prion peptide, which resembles the mammalian prion protein linked to spongiform encephalopathies. To facilitate the study of these important peptides, experimentalists have identified small peptide congeners of the full-length proteins that exhibit amyloidogenic behavior, including the KLVFFAE sub-sequence, Aβ16−22, and the GNNQQNY subsequence, Sup357−13. In this study, molecular dynamics simulations were used to examine these peptide fragments encapsulated in reverse micelles (RMs) in order to identify the fundamental principles that govern how sequence and solution environment influence peptide aggregation. Aβ16−22 and Sup357−13 are observed to organize into anti-parallel and parallel β-sheet arrangements. Confinement in the sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles is shown to stabilize extended peptide conformations and enhance peptide aggregation. Substantial fluctuations in the reverse micelle shape are observed, in agreement with earlier studies. Shape fluctuations are found to facilitate peptide solvation through interactions between the peptide and AOT surfactant, including direct interaction between non-polar peptide residues and the aliphatic surfactant tails. Computed amide I IR spectra are compared with experimental spectra and found to reflect changes in the peptide structures induced by confinement in the RM environment. Furthermore, examination of the rotational anisotropy decay of water in the RM demonstrates that the water dynamics are sensitive to the presence of peptide as well as the peptide sequence. Overall, our results

  10. Exploring the role of hydration and confinement in the aggregation of amyloidogenic peptides Aβ16-22 and Sup357-13 in AOT reverse micelles

    NASA Astrophysics Data System (ADS)

    Martinez, Anna Victoria; Małolepsza, Edyta; Rivera, Eva; Lu, Qing; Straub, John E.

    2014-12-01

    Knowledge of how intermolecular interactions of amyloid-forming proteins cause protein aggregation and how those interactions are affected by sequence and solution conditions is essential to our understanding of the onset of many degenerative diseases. Of particular interest is the aggregation of the amyloid-β (Aβ) peptide, linked to Alzheimer's disease, and the aggregation of the Sup35 yeast prion peptide, which resembles the mammalian prion protein linked to spongiform encephalopathies. To facilitate the study of these important peptides, experimentalists have identified small peptide congeners of the full-length proteins that exhibit amyloidogenic behavior, including the KLVFFAE sub-sequence, Aβ16-22, and the GNNQQNY subsequence, Sup357-13. In this study, molecular dynamics simulations were used to examine these peptide fragments encapsulated in reverse micelles (RMs) in order to identify the fundamental principles that govern how sequence and solution environment influence peptide aggregation. Aβ16-22 and Sup357-13 are observed to organize into anti-parallel and parallel β-sheet arrangements. Confinement in the sodium bis(2-ethylhexyl) sulfosuccinate (AOT) reverse micelles is shown to stabilize extended peptide conformations and enhance peptide aggregation. Substantial fluctuations in the reverse micelle shape are observed, in agreement with earlier studies. Shape fluctuations are found to facilitate peptide solvation through interactions between the peptide and AOT surfactant, including direct interaction between non-polar peptide residues and the aliphatic surfactant tails. Computed amide I IR spectra are compared with experimental spectra and found to reflect changes in the peptide structures induced by confinement in the RM environment. Furthermore, examination of the rotational anisotropy decay of water in the RM demonstrates that the water dynamics are sensitive to the presence of peptide as well as the peptide sequence. Overall, our results

  11. A new microRNA signal pathway regulated by long noncoding RNA TGFB2-OT1 in autophagy and inflammation of vascular endothelial cells

    PubMed Central

    Huang, ShuYa; Lu, Wei; Ge, Di; Meng, Ning; Li, Ying; Su, Le; Zhang, ShangLi; Zhang, Yun; Zhao, BaoXiang; Miao, JunYing

    2015-01-01

    TGFB2-OT1 (TGFB2 overlapping transcript 1) is a newly discovered long noncoding RNA (lncRNA) derived from the 3′UTR of TGFB2. It can regulate autophagy in vascular endothelial cells (VECs). However, the mechanisms of TGFB2-OT1 action are unclear, and whether it is involved in VECs dysfunction needs investigation. Here, the level of TGFB2-OT1 was markedly increased by lipopolysaccharide and oxidized low-density lipoprotein, 2 VECs inflammation triggers. A chemical small molecule, 3-benzyl-5-((2-nitrophenoxy) methyl)-dihydrofuran-2(3H)-one (3BDO) significantly decreased TGFB2-OT1 levels and inhibited the effect of LPS and oxLDL. The NUPR1 level was upregulated by the 2 inflammation inducers and modulated the TGFB2-OT1 level by promoting the expression of TIA1, responsible for TGFB2-OT1 processing. We focused on how TGFB2-OT1 regulated autophagy and inflammation. Use of miRNA chip assay, TGFB2-OT1 overexpression technology and 3BDO revealed that TGFB2-OT1 regulated the levels of 3 microRNAs, MIR3960, MIR4488 and MIR4459. Further studies confirmed that TGFB2-OT1 acted as a competing endogenous RNA, bound to MIR3960, MIR4488 and MIR4459, then regulated the expression of the miRNA targets CERS1 (ceramide synthase 1), NAT8L (N-acetyltransferase 8-like [GCN5-related, putative]), and LARP1 (La ribonucleoprotein domain family, member 1). CERS1 and NAT8L participate in autophagy by affecting mitochondrial function. TGFB2-OT1 increased the LARP1 level, which promoted SQSTM1 (sequestosome 1) expression, NFKB RELA and CASP1 activation, and then production of IL6, IL8 and IL1B in VECs. Thus, NUPR1 and TIA1 may control the level of TGFB2-OT1, and TGFB2-OT1 bound to MIR3960, MIR4488 and MIR4459, which targeted CERS1, NAT8L, and LARP1, respectively, the key proteins involved in autophagy and inflammation. PMID:26565952

  12. Atmospheric Chemistry: Nature's plasticized aerosols

    NASA Astrophysics Data System (ADS)

    Ziemann, Paul J.

    2016-01-01

    The structure of atmospheric aerosol particles affects their reactivity and growth rates. Measurements of aerosol properties over the Amazon rainforest indicate that organic particles above tropical rainforests are simple liquid drops.

  13. Palaeoclimate: Aerosols shift lake ecosystem

    NASA Astrophysics Data System (ADS)

    Dowsett, Harry J.

    2017-02-01

    Anthropogenic aerosols over the Chinese Loess Plateau have diminished monsoon precipitation and concomitant soil erosion that plagues the region. Now, a reconstruction documents the differences between historical warming events and the present, highlighting the paradoxical implications of decreasing atmospheric aerosols.

  14. Generation of aerosolized drugs.

    PubMed

    Wolff, R K; Niven, R W

    1994-01-01

    The expanding use of inhalation therapy has placed demands on current aerosol generation systems that are difficult to meet with current inhalers. The desire to deliver novel drug entities such as proteins and peptides, as well as complex formulations including liposomes and microspheres, requires delivery systems of improved efficiency that will target the lung in a reproducible manner. These efforts have also been spurred by the phase out of chlorofluorocarbons (CFCs) and this has included a directed search for alternative propellants. Consequently, a variety of new aerosol devices and methods of generating aerosols are being studied. This includes the use of freon replacement propellants, dry powder generation systems, aqueous unit spray systems and microprocessor controlled technologies. Each approach has advantages and disadvantages depending upon each principle of action and set of design variables. In addition, specific drugs may be better suited for one type of inhaler device vs. another. The extent to which aerosol generation systems achieve their goals is discussed together with a summary of selected papers presented at the recent International Congress of Aerosols in Medicine.

  15. Aerosol chemistry in GLOBE

    NASA Technical Reports Server (NTRS)

    Clarke, Antony D.; Rothermel, Jeffry; Jarzembski, Maurice A.

    1993-01-01

    This task addresses the measurement and understanding of the physical and chemical properties of aerosol in remote regions that are responsible for aerosol backscatter at infrared wavelengths. Because it is representative of other clean areas, the remote Pacific is of extreme interest. Emphasis is on the determination size dependent aerosol properties that are required for modeling backscatter at various wavelengths and upon those features that may be used to help understand the nature, origin, cycling and climatology of these aerosols in the remote troposphere. Empirical relationships will be established between lidar measurements and backscatter derived from the aerosol microphysics as required by the NASA Doppler Lidar Program. This will include the analysis of results from the NASA GLOBE Survey Mission Flight Program. Additional instrument development and deployment will be carried out in order to extend and refine this data base. Identified activities include participation in groundbased and airborne experiments. Progress to date includes participation in, analysis of, and publication of results from Mauna Loa Backscatter Intercomparison Experiment (MABIE) and Global Backscatter Experiment (GLOBE).

  16. Effect of Ozone Therapy (OT) on Healing of Colonic Anastomosis in a Rat Model of Peritonitis

    PubMed Central

    Erginel, Başak; Erginel, Turgay; Aksoy, Bilgin; Dokucu, Ali İhsan

    2014-01-01

    Background: Ozone is a three-oxygen molecule (O3). Ozone therapy (OT) is systematically effective when pathological inflammatory and immunologic processes are activated. Among of these conditions are wound healing, macular degeneration related to aging, and conditions that are ischemic or infectious. Aims: The aim of this study was to determine the effects of OT on wound healing of intestinal anastomosis in the presence of peritonitis in a rat model. Study Design: Animal experimentation. Methods: A total of 40 Wistar albino rats were randomized into four groups (n=10) including: sham (S), peritonitis (P), ozone 0 (O0), and ozone 24 (O24). In group S, only cecal dissection was carried out. The S group had only a cecal dissection and intestinal anastomosis performed, but no peritonitis. In all other groups, cecal ligation and puncture (CLP) followed the cecal dissection to induce bacterial peritonitis. 24 h after puncture, a cecal resection and ileocolic anastomosis were performed. In group P, 24 h after CLP, a cecal resection and ileocolic anastomosis were performed and no ozone was administered. In group O0, immediately after the anastomosis, and in group O24, starting 24 hours after the anastomosis, an intraperitoneal 1 mg/kg/day ozone administration was applied for seven days. On the seventh day the animals were sacrificed, the anastomotic bursting pressures (BP) and the hydroxyproline values of the anastomotic tissues were measured, and histopathologic examination of the anastomotic segment was carried out. Results: The highest BP was in group S, with 211±23.13 mmHg. The mean BP of group P was 141±56.25 mmHg, which was significantly lower than in the other two peritonitis groups that received ozone therapy, group O0 and O24, where it was 192±22 and 166±45 mmHg, respectively (p<0.05). The difference in the BP between groups O0 and O24 was not statistically significant (p>0.05). Histopathologic analyses of the anastomotic segments determined there was

  17. Remote sensing of the aerosol in Cairo (Egypt): compositional variability and impact on the atmospheric transfer of solar radiation

    NASA Astrophysics Data System (ADS)

    Alfaro, Stephane; El-Metwally, Mossad; Favez, Olivier; Chatenet, Bernadette; Abdel Wahab, Magdy

    2010-05-01

    Cairo, the capital city of Egypt, is located at the southernmost tip of the Nile Delta and is surrounded on the other three sides by deserts. As is the case in several other megacities of the World, its fast increasing population already suffers from a general worsening of their environmental conditions, and in particular of the air quality. In order to investigate the reasons for this degradation and clarify the respective parts played by human activities, meteorological factors, and other natural processes, the Cairo Aerosol CHaracterization Experiment (CACHE) was designed and carried out in the city by an Egyptian-French consortium. After a rapid presentation of the local context and of the measurements performed during CACHE, this work focuses on the results obtained by the means of various remote sensing techniques. We first present the seasonal and inter-annual variability of the atmospheric aerosol load using 8 years of measurements performed by the Aqua-, and Terra-, MODIS radiometers. In a second step we investigate the reasons of this variability observed from space by analyzing in detail the results yielded by inversion of the measurements performed with a ground-based radiometer. This automated sun-tracking photometer was of the Cimel type, included in the AERONET network, and operated in Cairo for more than one year. The month to month variations of the aerosol optical thickness (AOT) and of its spectral dependence quantified by the means of Angström's exponent () can be explained by compositional changes. In particular, the proportions of the main aerosol components are sensitive to the activation of seasonal sources such as wind erosion particularly active in spring or the burning of agricultural residues by the farmers of the Nile Delta in October. Beside wind strength, whose increase triggers wind erosion in the deserts, other meteorological factors such as wind direction or more frequent precipitations in the winter months also have a direct

  18. An AFM Study of the Effects of Silanization Temperature, Hydration, and Annealing on the Nucleation and Aggregation of Condensed OTS Domains on Mica.

    PubMed

    Britt, David W; Hlady, Vladimir

    1996-03-25

    Partial monolayers of octadecyltrichlorosilane (OTS) were formed on mica under different reaction conditions in which the silanization temperature, time, and amount of water adsorbed on the mica substrates were varied. OTS surface coverage increased with silanization time for all samples; however, the amount and distribution of adsorbed OTS varied greatly under these different reaction conditions. AFM analysis showed that OTS formed two phases on mica silanized at 25°C: condensed "island-like" domains and expanded "liquid-like" domains. Partially dehydrated mica silanized at 9°C, however, displayed only condensed domains which were of smaller size compared to those on the 25°C samples. The lateral diffusion and aggregation of small condensed OTS domains to form larger aggregates was evident on all surfaces except the 25°C partially dehydrated mica. A uniform distribution of many small condensed domains surrounded by expanded OTS phases was seen instead. Extended annealing resulted in surface diffusion and aggregation of these domains and nucleation of new condensed domains from the surrounding expanded OTS phases. These observations are consistent with a deposition, diffusion, and aggregation model (DDA) which allows for activated diffusion; however, rigorous modeling is not presented here.

  19. Over-Expression of the Mycobacterial Trehalose-Phosphate Phosphatase OtsB2 Results in a Defect in Macrophage Phagocytosis Associated with Increased Mycobacterial-Macrophage Adhesion

    PubMed Central

    Li, Hao; Wu, Mei; Shi, Yan; Javid, Babak

    2016-01-01

    Trehalose-6-phosphate phosphatase (OtsB2) is involved in the OtsAB trehalose synthesis pathway to produce free trehalose and is strictly essential for mycobacterial growth. We wished to determine the effects of OtsB2 expression on mycobacterial phenotypes such as growth, phagocytosis and survival in macrophages. Mycobacterium bovis-bacillus calmette-guerin (BCG) over-expressing OtsB2 were able to better survive in stationary phase. Over-expression of OtsB2 led to a decrease in phagocytosis but not survival in THP-1 macrophage-like cells, and this was not due to a decrease in general macrophage phagocytic activity. Surprisingly, when we investigated macrophage–mycobacterial interactions by flow cytometry and atomic force microscopy, we discovered that BCG over-expressing OtsB2 have stronger binding to THP-1 cells than wild-type BCG. These results suggest that altering OtsB2 expression has implications for mycobacterial host–pathogen interactions. Macrophage–mycobacteria phagocytic interactions are complex and merit further study. PMID:27867377

  20. The catalytic efficiency of lipase in a novel water-in-[Bmim][PF6] microemulsion stabilized by both AOT and Triton X-100.

    PubMed

    Xue, Luyan; Li, Ying; Zou, Feixue; Lu, Lu; Zhao, Yin; Huang, Xirong; Qu, Yinbo

    2012-04-01

    In the water-in-[Bmim][PF(6)] microemulsion stabilized by both AOT and Triton X-100, the lipase-catalyzed hydrolysis of 4-nitrophenyl butyrate (p-NPB) was investigated to evaluate the catalytic efficiency of lipase in this novel microemulsion. The structural parameters of the microemulsion and the conditions of the enzymatic reaction affect the catalytic activity of lipase, especially the concentration of Tris-HCl buffer. Under optimum conditions, the catalytic activity of lipase in the present microemulsion is much higher than that in H(2)O saturated [Bmim][PF(6)]. When the partitioning of the substrate in the microemulsion is taken into account, the catalytic efficiency of lipase in this novel microemulsion is 14.3 times that in H(2)O saturated [Bmim][PF(6)] due to the significant decrease of the Michaelis constant in the microemulsion. Due to the large interface, high water activity, and probably the activating effect of the imidazolium cation in the water pool, the present microemulsion is demonstrated to be a promising medium for the lipase-catalyzed hydrolytic reaction. To demonstrate an important biocatalytic application in the IL-based microemulsion, the lipase-catalyzed synthesis of the flavoring agent benzyl acetate via transesterification of vinyl acetate with benzyl alcohol was also studied in the medium. Due to the high dispersion of lipase, large interface and removal of the byproduct, a maximum yield of 94% was obtained, indicating that the novel microemulsion is really important and useful.

  1. Determination of the acid dissociation constant of bromocresol green and cresol red in water/AOT/isooctane reverse micelles by multiple linear regression and extended principal component analysis.

    PubMed

    Caselli, Maurizio; Mangone, Annarosa; Paolillo, Paola; Traini, Angela

    2002-01-01

    The pKa of 3',3",5',5"tetrabromo-m-cresolsulfonephtalein (Bromocresol Green) and o-cresolsulphonephtalein (Cresol Red) was spectrophotometrically measured in a water/AOT/isooctane microemulsion in the presence of a series of buffers carrying different charges at different water/surfactant ratios. Extended Principal Component Analysis was used for a precise determination of the apparent pKa and of the spectra of the acid and base forms of the dye. The apparent pKa of dyes in water-in-oil microemulsions depends on the charge of the acid and base forms of the buffers present in the water pool. Combination with multiple linear regression increases the precision. Results are discussed taking into account the profile of the electrostatic potential in the water pool and the possible partition of the indicator between the aqueous core and the surfactant. The pKa corrected for these effects are independent of w0 and are close to the value of the pKa in bulk water. On the basis of a tentative hypothesis it is possible to calculate the true pKa of the buffer in the pool.

  2. Relation between aerosol particles and their optical properties: a case study for São Paulo-Brazil

    NASA Astrophysics Data System (ADS)

    Miranda, Regina; Andrade, Maria de Fatima

    2013-04-01

    from mineral dust (Al, Si, Ca, Fe), anthropogenic particles and the burning of diesel (S), as well as from industries and residual oil combustion. Considering the trace element values obtained through EDXRF analysis, Angstron coefficients and Aerosol Optical Thickness (AOT 500 nm) were correlated (Pearson Correlation) to particulate and chemical elements. Soil elements have a positive correlation, fine particles are strong correlated to AOT. Elements like Fe, Si and Ca are usually related to larger particles and lower Angstron coefficients.

  3. Isolation and Pharmacological Characterization of α-Elapitoxin-Ot1a, a Short-Chain Postsynaptic Neurotoxin from the Venom of the Western Desert Taipan, Oxyuranus temporalis

    PubMed Central

    Barber, Carmel M.; Ahmad Rusmili, Muhamad Rusdi; Hodgson, Wayne C.

    2016-01-01

    Taipans (Oxyuranus spp.) are elapids with highly potent venoms containing presynaptic (β) and postsynaptic (α) neurotoxins. O. temporalis (Western Desert taipan), a newly discovered member of this genus, has been shown to possess venom which displays marked in vitro neurotoxicity. No components have been isolated from this venom. We describe the characterization of α-elapitoxin-Ot1a (α-EPTX-Ot1a; 6712 Da), a short-chain postsynaptic neurotoxin, which accounts for approximately 30% of O. temporalis venom. α-Elapitoxin-Ot1a (0.1–1 µM) produced concentration-dependent inhibition of indirect-twitches, and abolished contractile responses to exogenous acetylcholine and carbachol, in the chick biventer cervicis nerve-muscle preparation. The inhibition of indirect twitches by α-elapitoxin-Ot1a (1 µM) was not reversed by washing the tissue. Prior addition of taipan antivenom (10 U/mL) delayed the neurotoxic effects of α-elapitoxin-Ot1a (1 µM) and markedly attenuated the neurotoxic effects of α-elapitoxin-Ot1a (0.1 µM). α-Elapitoxin-Ot1a displayed pseudo-irreversible antagonism of concentration-response curves to carbachol with a pA2 value of 8.02 ± 0.05. De novo sequencing revealed the main sequence of the short-chain postsynaptic neurotoxin (i.e., α-elapitoxin-Ot1a) as well as three other isoforms found in O. temporalis venom. α-Elapitoxin-Ot1a shows high sequence similarity (i.e., >87%) with other taipan short-chain postsynaptic neurotoxins. PMID:26938558

  4. Chemical aerosol Raman detector

    NASA Astrophysics Data System (ADS)

    Aggarwal, R. L.; Farrar, L. W.; Di Cecca, S.; Amin, M.; Perkins, B. G.; Clark, M. L.; Jeys, T. H.; Sickenberger, D. W.; D'Amico, F. M.; Emmons, E. D.; Christesen, S. D.; Kreis, R. J.; Kilper, G. K.

    2017-03-01

    A sensitive chemical aerosol Raman detector (CARD) has been developed for the trace detection and identification of chemical particles in the ambient atmosphere. CARD includes an improved aerosol concentrator with a concentration factor of about 40 and a CCD camera for improved detection sensitivity. Aerosolized isovanillin, which is relatively safe, has been used to characterize the performance of the CARD. The limit of detection (SNR = 10) for isovanillin in 15 s has been determined to be 1.6 pg/cm3, which corresponds to 6.3 × 109 molecules/cm3 or 0.26 ppb. While less sensitive, CARD can also detect gases. This paper provides a more detailed description of the CARD hardware and detection algorithm than has previously been published.

  5. Stratospheric Aerosol Measurements

    NASA Technical Reports Server (NTRS)

    Pueschel, Rudolf, F.; Gore, Warren J. (Technical Monitor)

    1998-01-01

    Stratospheric aerosols affect the atmospheric energy balance by scattering and absorbing solar and terrestrial radiation. They also can alter stratospheric chemical cycles by catalyzing heterogeneous reactions which markedly perturb odd nitrogen, chlorine and ozone levels. Aerosol measurements by satellites began in NASA in 1975 with the Stratospheric Aerosol Measurement (SAM) program, to be followed by the Stratospheric Aerosol and Gas Experiment (SAGE) starting in 1979. Both programs employ the solar occultation, or Earth limb extinction, techniques. Major results of these activities include the discovery of polar stratospheric clouds (PSCs) in both hemispheres in winter, illustrations of the impacts of major (El Chichon 1982 and Pinatubo 1991) eruptions, and detection of a negative global trend in lower stratospheric/upper tropospheric aerosol extinction. This latter result can be considered a triumph of successful worldwide sulfur emission controls. The SAGE record will be continued and improved by SAGE III, currently scheduled for multiple launches beginning in 2000 as part of the Earth Observing System (EOS). The satellite program has been supplemented by in situ measurements aboard the ER-2 (20 km ceiling) since 1974, and from the DC-8 (13 km ceiling) aircraft beginning in 1989. Collection by wire impactors and subsequent electron microscopic and X-ray energy-dispersive analyses, and optical particle spectrometry have been the principle techniques. Major findings are: (1) The stratospheric background aerosol consists of dilute sulfuric acid droplets of around 0.1 micrometer modal diameter at concentration of tens to hundreds of monograms per cubic meter; (2) Soot from aircraft amounts to a fraction of one percent of the background total aerosol; (3) Volcanic eruptions perturb the sulfuric acid, but not the soot, aerosol abundance by several orders of magnitude; (4) PSCs contain nitric acid at temperatures below 195K, supporting chemical hypotheses

  6. Highly stable aerosol generator

    SciTech Connect

    DeFord, Henry S.; Clark, Mark L.

    1981-01-01

    An improved compressed air nebulizer has been developed such that a uniform aerosol particle size and concentration may be produced over long time periods. This result is achieved by applying a vacuum pressure to the makeup assembly and by use of a vent tube between the atmosphere and the makeup solution. By applying appropriate vacuum pressures to the makeup solution container and by proper positioning of the vent tube, a constant level of aspirating solution may be maintained within the aspirating assembly with aspirating solution continuously replaced from the makeup solution supply. This device may also be adapted to have a plurality of aerosol generators and only one central makeup assembly.

  7. Highly stable aerosol generator

    DOEpatents

    DeFord, H.S.; Clark, M.L.

    1981-11-03

    An improved compressed air nebulizer has been developed such that a uniform aerosol particle size and concentration may be produced over long time periods. This result is achieved by applying a vacuum pressure to the makeup assembly and by use of a vent tube between the atmosphere and the makeup solution. By applying appropriate vacuum pressures to the makeup solution container and by proper positioning of the vent tube, a constant level of aspirating solution may be maintained within the aspirating assembly with aspirating solution continuously replaced from the makeup solution supply. This device may also be adapted to have a plurality of aerosol generators and only one central makeup assembly. 2 figs.

  8. Almost gone: SN 2008S and NGC 300 2008OT-1 are fainter than their progenitors

    NASA Astrophysics Data System (ADS)

    Adams, S. M.; Kochanek, C. S.; Prieto, J. L.; Dai, X.; Shappee, B. J.; Stanek, K. Z.

    2016-08-01

    We present late-time Hubble and Spitzer Space Telescope (SST) imaging of SN 2008S and NGC 300 2008OT-1, the prototypes of a common class of stellar transients whose true nature is debated. Both objects are still fading and are now >15 times fainter than their progenitors in the mid-IR and are undetected in the optical and near-IR. Data from the Large Binocular Telescope and Magellan show that neither source has been variable in the optical since fading in 2010. We present models of surviving sources obscured by dusty shells or winds and find that extreme dust models are needed for surviving stars to be successfully hidden by dust, which suggests that these transients may be genuine, but low-energy, supernova explosions. Though SN 2008S is not detected in Chandra X-Ray Observatory data taken in 2012, the flux limits allow the fading IR source to be powered solely by the shock interaction of ejecta with the circumstellar medium if the shock velocity at the time of the observation was ≳20 per cent slower than estimated from emission line widths while the transient was still optically bright. Continued SST monitoring and 10-20 μm observations with James Webb Space Telescope can resolve any remaining ambiguities.

  9. The luminous red nova M101-OT2015-1: a candidate for common envelope ejection

    NASA Astrophysics Data System (ADS)

    Blagorodnova, Nadejda; Kasliwal, Mansi M.; Kotak, Rubina

    2017-01-01

    Binary interaction is an important phase in the study of stellar evolution. Approximately 50% of O star population live in close binary systems as to allow interaction with the companion. Although massive binary progenitors have been associated with thermonuclear supernovae, stripped core collapse supernovae, cataclysmic variables, X-ray binaries, or the mind blowing massive binary black holes recently detected by LIGO, the exact evolutionary path followed by the system is still under debate. One of the critical phases is the common envelope (CE) phase, required to bring a long period binary into a much shorter orbit. Currently, this phase also represents a challenge for the current stellar evolution models. Given the uncertainty, observational constraints are valuable input to advance in this field. One particular class of transient objects, called Luminous Red Novae (LRNe), has been associated with the termination of the CE phase, when a total or partial ejection of the least bound layers of the primary star are expelled at the expense of decreasing the orbital energy of the system. In my talk I will discuss the results of 16 years of observations of M101-OT2015-1, a LRN in M101 galaxy. I will describe the progenitor star (system) and the main characteristics of the outburst. Finally, I will present the results of the evolution of its remnant in infrared wavelengths. Given the long time span of our observations, this event represents one of the best studied CE ejection candidate at extragalactic distances.

  10. Partial KCNQ1OT1 hypomethylation: A disguised familial Beckwith–Wiedemann syndrome as a sporadic adrenocortical tumor

    PubMed Central

    H'mida Ben-Brahim, Dorra; Hammami, Sabeur; Haddaji Mastouri, Marwa; Trabelsi, Saoussen; Chourabi, Maroua; Sassi, Sihem; Mougou, Soumaya; Gribaa, Moez; Zakhama, Abdelfattah; Guédiche, Mohamed Neji; Saad, Ali

    2014-01-01

    Beckwith–Wiedemann syndrome has a wide spectrum of complications such as embryonal tumors, namely adrenocortical tumor. Tumor predisposition is one of the most challenging manifestations of this syndrome. A 45-day old female with a family history of adrenocortical tumor presented with adrenocortical tumor. The case raised suspicion of a hereditary Beckwith–Wiedemann syndrome, therefore molecular analysis was undertaken. The results revealed partial KCNQ1OT1 hypomethylation in the infant's blood DNA which was associated with a complete loss of methylation in the infant's adrenocortical tumor tissue. It is unique for familial Beckwith–Wiedemann syndrome caused by KCNQ1OT1 partial hypomethylation to manifest solely through adrenocortical tumor. Incomplete penetrance and specific tissue mosaicism could provide explanations to this novel hereditary Beckwith–Wiedemann syndrome presentation. PMID:26937341

  11. MASTER OT J130845.02-323254.9: Variable Stars as Source of the High Energy Neutrino.

    NASA Astrophysics Data System (ADS)

    Lipunov, V.; Tyurina, N.; Gorbovskoy, E.; Buckley, D.

    2016-09-01

    As reported in ATel #9425 Global MASTER Net auto-detection system ( ( Lipunov et al., MASTER Global Robotic Net, Advances in Astronomy, 2010, 30L) discovered OT source at (RA, Dec) = 13h 08m 45.02s -32d 32m 54.9s on 2016-08-24.73811 UT during inspection of HESE IceCube alert (14 August 2016, 58537957 trigger number http://gcn.gsfc.nasa.gov/notices_amon/58537957_128340.amon , Dornic et al. ATEL #9440 ). MASTER-SAAO auto-detection system detected again OT at RA (2000) = 13 08 45.02 -32 32 54.9 on 2016-09-04.7627UT (ATEL #9425).

  12. Limited Production (LP) Precision Runway Monitor (PRM) Operational Test and Evaluation integration and OT and E Operational Test Plan

    NASA Astrophysics Data System (ADS)

    Livings, Jeffrey

    1995-05-01

    This document defines the Test Plan and corresponding Test Verification Requirements Traceability Matrix (TVRTM) that will be used to conduct the Limited Production (LP) Precision Runway Monitor (PRM) Operational Test and Evaluation (OT and E) Integration and OT and E Operational tests. These tests will be conducted at the Minneapolis-St. Paul International Airport following the Contractor Site Acceptance Test. The LP PRM OT and E test effort will concentrate on Operational Effectiveness and Suitability. The Operational Effectiveness Test consists of a review of the contractor performed Development Test and Evaluation (DT and E) and Site Acceptance Tests. This review will evaluate whether each of the Measures of Effectiveness had been satisfactorily tested and whether the results meet the Minimum Acceptable Operational REquirements MAORs). This review will be conducted solely by test engineers and does not require the PRM system. The Operational Suitability Tests will expose the test participants (Air Traffic (AT) Controllers and Airway Facilities (AF) Technicians) to the PRM system in an operational environment while they perform specified operational procedures. These tests will be conducted in two separate phases: AT Suitability and AF Suitability. Each of these phases is focused on the specific test participants.

  13. Aerosol contributions to speleothem geochemistry

    NASA Astrophysics Data System (ADS)

    Dredge, J. A.; Fairchild, I. J.; Harrison, R.; Woodhead, J. D.; Hellstrom, J.

    2011-12-01

    The term "aerosols" encompasses the suspension of both fine solid or liquid particles within a gaseous medium. Aerosols become suspended into the earth's atmosphere through a multitude of processes both natural and anthropogenic. Atmospheric aerosols enter cave networks as a result of cave ventilation processes and are either deposited, or cycled and removed from the system. Speleothem offer a multiproxy palaeoclimate resource; many of the available proxies have been extensively investigated and utilised for palaeoclimatic reconstructions in a range of studies. The potential contribution of aerosols to speleothem chemistry and their applicability for palaeoenvironmental reconstructions remains untested and the extent of their value as an addition to palaeoclimate sciences unknown. Aerosols through incorporation into speleothem may provide a novel palaeoenvironmental resource. The aerosol component of interest is that which is transported into the cave atmosphere and deposited and are available for incorporation into precipitated calcite. Aerosol deposition and therefore distribution in the cave has shown to be a complex function of ventilation and changing environmental factors. Through detailed monitoring aerosols have been detected, identified, characterised and quantified to determine their prominence in the cave system. Investigations are on a case study basis, searching for suitable aerosol proxies of environmentally significant emission processes. Case studies include: Palaeofires at Yarrangobilly Caves, Australia; anthropogenic emissions at St Michaels Cave, Gibraltar and Cheddar gorge, UK; and drip water aerosol production and geochemical addition in Obir cave, Austria. Monitoring has allowed for the temporal and spatial determination of aerosols in karst networks. Speleothem samples will be analysed in combination with in-situ monitoring to determine incorporation factors and record preservation. By understanding how aerosols are transmitted within the

  14. Impaired Memory in OT-II Transgenic Mice Is Associated with Decreased Adult Hippocampal Neurogenesis Possibly Induced by Alteration in Th2 Cytokine Levels

    PubMed Central

    Jeon, Seong Gak; Kim, Kyoung Ah; Chung, Hyunju; Choi, Junghyun; Song, Eun Ji; Han, Seung-Yun; Oh, Myung Sook; Park, Jong Hwan; Kim, Jin-il; Moon, Minho

    2016-01-01

    Recently, an increasing number of studies have focused on the effects of CD4+ T cell on cognitive function. However, the changes of Th2 cytokines in restricted CD4+ T cell receptor (TCR) repertoire model and their effects on the adult hippocampal neurogenesis and memory are not fully understood. Here, we investigated whether and how the mice with restricted CD4+ repertoire TCR exhibit learning and memory impairment by using OT-II mice. OT-II mice showed decreased adult neurogenesis in hippocampus and short- and long- term memory impairment. Moreover, Th2 cytokines in OT-II mice are significantly increased in peripheral organs and IL-4 is significantly increased in brain. Finally, IL-4 treatment significantly inhibited the proliferation of cultured adult rat hippocampal neural stem cells. Taken together, abnormal level of Th2 cytokines can lead memory dysfunction via impaired adult neurogenesis in OT-II transgenic. PMID:27432189

  15. Impaired Memory in OT-II Transgenic Mice Is Associated with Decreased Adult Hippocampal Neurogenesis Possibly Induced by Alteration in Th2 Cytokine Levels.

    PubMed

    Jeon, Seong Gak; Kim, Kyoung Ah; Chung, Hyunju; Choi, Junghyun; Song, Eun Ji; Han, Seung-Yun; Oh, Myung Sook; Park, Jong Hwan; Kim, Jin-Il; Moon, Minho

    2016-08-31

    Recently, an increasing number of studies have focused on the effects of CD4+ T cell on cognitive function. However, the changes of Th2 cytokines in restricted CD4+ T cell receptor (TCR) repertoire model and their effects on the adult hippocampal neurogenesis and memory are not fully understood. Here, we investigated whether and how the mice with restricted CD4+ repertoire TCR exhibit learning and memory impairment by using OT-II mice. OT-II mice showed decreased adult neurogenesis in hippocampus and short- and long- term memory impairment. Moreover, Th2 cytokines in OT-II mice are significantly increased in peripheral organs and IL-4 is significantly increased in brain. Finally, IL-4 treatment significantly inhibited the proliferation of cultured adult rat hippocampal neural stem cells. Taken together, abnormal level of Th2 cytokines can lead memory dysfunction via impaired adult neurogenesis in OT-II transgenic.

  16. American Association for Aerosol Research (AAAR) `95

    SciTech Connect

    1995-12-31

    The Fourteenth annual meeting of the American Association for Aerosol Research was held October 9-13, 1995 at Westin William Penn Hotel in Pittsburgh, PA. This volume contains the abstracts of the papers and poster sessions presented at this meeting, grouped by the session in which they were presented as follows: Radiation Effects; Aerosol Deposition; Collision Simulations and Microphysical Behavior; Filtration Theory and Measurements; Materials Synthesis; Radioactive and Nuclear Aerosols; Aerosol Formation, Thermodynamic Properties, and Behavior; Particle Contamination Issues in the Computer Industry; Pharmaceutical Aerosol Technology; Modeling Global/Regional Aerosols; Visibility; Respiratory Deposition; Biomass and Biogenic Aerosols; Aerosol Dynamics; Atmospheric Aerosols.

  17. Knockdown of Long Non-Coding RNA KCNQ1OT1 Restrained Glioma Cells’ Malignancy by Activating miR-370/CCNE2 Axis

    PubMed Central

    Gong, Wei; Zheng, Jian; Liu, Xiaobai; Liu, Yunhui; Guo, Junqing; Gao, Yana; Tao, Wei; Chen, Jiajia; Li, Zhiqing; Ma, Jun; Xue, Yixue

    2017-01-01

    Accumulating evidence has highlighted the potential role of long non-coding RNAs (lncRNAs) as biomarkers and therapeutic targets in solid tumors. Here, we elucidated the function and possible molecular mechanisms of lncRNA KCNQ1OT1 in human glioma U87 and U251 cells. Quantitative Real-Time polymerase chain reaction (qRT-PCR) demonstrated that KCNQ1OT1 expression was up-regulated in glioma tissues and cells. Knockdown of KCNQ1OT1 exerted tumor-suppressive function in glioma cells. Moreover, a binding region was confirmed between KCNQ1OT1 and miR-370 by dual-luciferase assays. qRT-PCR showed that miR-370 was down-regulated in human glioma tissue and cells. In addition, restoration of miR-370 exerted tumor-suppressive function via inhibiting cell proliferation, migration and invasion, while promoting the apoptosis of human glioma cells. Knockdown of KCNQ1OT1 decreased the expression level of Cyclin E2 (CCNE2) by binding to miR-370. Further, miR-370 bound to CCNE2 3′UTR region and decreased the expression of CCNE2. These results provided a comprehensive analysis of KCNQ1OT1-miR-370-CCNE2 axis in human glioma cells and might provide a novel strategy for glioma treatment. PMID:28381990

  18. Determination of aerosol ammonium using an aerodyne aerosol mass spectrometer

    NASA Astrophysics Data System (ADS)

    Delia, A. E.; Toohey, D. W.; Worsnop, D. R.

    2003-04-01

    The chemical composition of fine aerosols is a significant issue both because it influences the chemical and radiative properties of the aerosols, which in turn impact the regional and global climate and human health, and because it is difficult to measure accurately. The Aerosol Mass Spectrometer (AMS) developed by Aerodyne Research measures both chemical composition and aerodynamic size of submicron aerosols quantitatively. However, the measurement of aerosol ammonium is more difficult than that of the other major inorganic species, nitrate and sulfate, because of interferences in the mass spectrum from air and water. This presentation will describe the successful procedure developed for dealing with these interferences and accurately determining the ammonium mass. In addition, the application of this procedure to aerosols from a range of ambient conditions will be demonstrated using data from several field studies.

  19. Charicteristics of Aerosol indices distribution followed by Aerosol types

    NASA Astrophysics Data System (ADS)

    Park, S.; Kim, J.; Lee, J.; Kim, M.; Lee, S.; Song, C.

    2010-12-01

    Transboundary transport of aerosol has been a hot issue in East Asia and with various aerosol types from different source region. To detect signals from aerosols, OMI provides aerosol indices. Aerosol Indices (AI) represent the change of spectral contrast between two wavelengths and these indices are derived in UV and Visible regions. These indices also can get not only in ocean but also in land region so that AI is good to observe the source region and transport of aerosols. In UV region, AI (UV-AI) can classify the absorbing and non-absorbing aerosols (Torres et al., 1998) so that this value is frequently used for dust detection. Additionally, visible AI (VIS-AI) uses to differentiate the absorbing and non-absorbing aerosol types. If we combine two types of indices at the coordinate system of two types of AI, distribution of indices contains different signals if aerosol types change theoretically. In this study, we want to find out classification results based by the observation data to see the theoretical distribution in two AI values. For the observation data, aerosol types are obtained from the results of MODIS-OMI algorithm and 4-channel algorithm classify four types of aerosols, i.e. dust, carbonaceous, sea-salt and Non-Absorbing (NA). These algorithms classify aerosol by using the characteristics of aerosol optical properties in visible and near IR regions. MODIS-OMI algorithm uses the MODIS AOD and UV-AI in OMI values. For UV-AI case, dust and carbonaceous types have larger UV-AI values than non-absorbing aerosols because of absorbing characteristics. However, dust and carbonaceous types cannot classify if UV-AI values use only. For VIS-AI case, dust has larger proportion, but carbonaceous aerosol has smaller proportion in high AI value. However, VIS-AI cannot clearly classify between dust and carbonaceous types except for the case of extremely high AI cases. In NA type, VIS-AI has almost positive values, but the distribution has smaller than the absorbing

  20. Aerosol meteorology of the Maritime Continent for the 2012 7SEAS southwest monsoon intensive study - Part 1: regional-scale phenomena

    NASA Astrophysics Data System (ADS)

    Reid, Jeffrey S.; Xian, Peng; Holben, Brent N.; Hyer, Edward J.; Reid, Elizabeth A.; Salinas, Santo V.; Zhang, Jianglong; Campbell, James R.; Chew, Boon Ning; Holz, Robert E.; Kuciauskas, Arunas P.; Lagrosas, Nofel; Posselt, Derek J.; Sampson, Charles R.; Walker, Annette L.; Welton, E. Judd; Zhang, Chidong

    2016-11-01

    counts were middling, resultant AERONET 500 nm aerosol optical thickness (AOT) from fire activity was high, with maximums of 3.6 and 5.6 in the Sumatra and Kalimantan source regions at the end of the burning season and an average of ˜ 1. AOTs could also be high at receptor sites, with a mean and maximum of 0.57 and 1.24 in Singapore and 0.61 and 0.8 in Kuching Sarawak. Ultimately, outside of the extreme 2015 El Niño event, average AERONET AOT values were higher than any other time since sites were established. Thus, while satellite fire data, models, and AERONET all qualitatively agree on the nature of smoke production and transport, the MC's complex environment resulted in clear differences in quantitative interpretation of these datasets.

  1. Aerosol Dynamics Laboratory

    SciTech Connect

    Rader, D.J.; Mondy, L.A.

    1990-04-01

    In past five years, Department 1510 has developed a state-of-the-art Aerosol Dynamics Laboratory (ADL). This report documents the current instrumentation and capabilities that exist in this laboratory. The ADL was developed from a variety of sources, with a primary contribution from Department 1510's Independent Research and Development program in aerosol dynamics. Current capabilities of the ADL include: (1) generation of calibration-quality monodisperse particles with diameters between 0.005 to 100 {mu}m, (2) real-time measurement of particle size distributions for particle diameters between 0.01 and 100 {mu}m, (3) in situ, real-time measurement of particle size distributions for particle diameters between 0.3 and 100 {mu}m, and (4) real-time measurement of particle charge distributions for particle diameters between 0.01 and 1.0 {mu}m. 14 refs., 5 figs.

  2. Aerosol Observing System (AOS) Handbook

    SciTech Connect

    Jefferson, A

    2011-01-17

    The Aerosol Observing System (AOS) is a suite of in situ surface measurements of aerosol optical and cloud-forming properties. The instruments measure aerosol properties that influence the earth’s radiative balance. The primary optical measurements are those of the aerosol scattering and absorption coefficients as a function of particle size and radiation wavelength and cloud condensation nuclei (CCN) measurements as a function of percent supersaturation. Additional measurements include those of the particle number concentration and scattering hygroscopic growth. Aerosol optical measurements are useful for calculating parameters used in radiative forcing calculations such as the aerosol single-scattering albedo, asymmetry parameter, mass scattering efficiency, and hygroscopic growth. CCN measurements are important in cloud microphysical models to predict droplet formation.

  3. Atmospheric aerosols: Their Optical Properties and Effects

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Measured properties of atmospheric aerosol particles are presented. These include aerosol size frequency distribution and complex retractive index. The optical properties of aerosols are computed based on the presuppositions of thermodynamic equilibrium and of Mie-theory.

  4. Improvement of Aerosol Prediction Capability

    DTIC Science & Technology

    2001-09-30

    by dust storms in the past.) The operational aerosol products will be used for initialization or specification of aerosols in COAMPS when new cloud...Figure 2. SeaWiFS visible imagery for May 18, 2001, showing a dust storm originating at dry lakes along the Iran-Afghanistan border and then...versions of the Navy Aerosol Analysis and Prediction System (NAAPS) for analysis of airborne dust loads (Westphal/NRL). B: Modify existing radiative

  5. Unified Aerosol Microphysics for NWP

    DTIC Science & Technology

    2011-09-30

    Specifically, the goal is to develop a COAMPS that is capable of simulating the full range of interactions between aerosol particles, clouds , and radiative...aerosol species that are responsible for degradation of Electro- Optical (EO) propagation or that modify cloud behavior and lifetime. Report...enabling new development of more complex cloud -aerosol interactions. The work on this project has been divided into two phases, an investigation phase

  6. Photothermal spectroscopy of aerosols

    SciTech Connect

    Campillo, A.J.; Lin, H.B.

    1981-04-01

    In situ aerosol absorption spectroscopy was performed using two novel photothermal detection schemes. The first, based on a photorefractive effect and coherent detection, called phase fluctuation optical heterodyne (PFLOH) spectroscopy, could, depending on the geometry employed, yield particle specific or particle and gas absorption data. Single particles of graphite as small as 1 ..mu..m were detected in the particle specific mode. In another geometrical configuration, the total absorption (both gas and particle) of submicron sized aerosols of ammonium sulfate particles in equilibrium with gaseous ammonia and water vapor were measured at varying CO/sub 2/ laser frequencies. The specific absorption coefficient for the sulfate ion was measured to be 0.5 m/sup 2//g at 1087 cm/sup -1/. The absorption coefficient sensitivity of this scheme was less than or equal to 10/sup -8/ cm/sup -1/. The second scheme is a hybrid visible Mie scattering scheme incorporating photothermal modulation. Particle specific data on ammonium sulfate droplets were obtained. For chemically identical species, the relative absorption spectrum versus laser frequency can be obtained for polydisperse aerosol distributions directly from the data without the need for complex inverse scattering calculations.

  7. Volcanic aerosols and lunar eclipses.

    PubMed

    Keen, R A

    1983-12-02

    The moon is visible during total lunar eclipses due to sunlight refracted into the earth's shadow by the atmosphere. Stratospheric aerosols can profoundly affect the brightness of the eclipsed moon. Observed brightnesses of 21 lunar eclipses during 1960-1982 are compared with theoretical calculations based on refraction by an aerosol-free atmosphere to yield globally averaged aerosol optical depths. Results indicate the global aerosol loading from the 1982 eruption of El Chichón is similar in magnitude to that from the 1963 Agung eruption.

  8. Characterization of the archaeal ribonuclease P proteins from Pyrococcus horikoshii OT3.

    PubMed

    Terada, Atsushi; Honda, Takashi; Fukuhara, Hideo; Hada, Kazumasa; Kimura, Makoto

    2006-08-01

    Ribonuclease P (RNase P) is a ribonucleoprotein complex involved in the processing of the 5'-leader sequence of precursor tRNA (pre-tRNA). Our earlier study revealed that RNase P RNA (pRNA) and five proteins (PhoPop5, PhoRpp38, PhoRpp21, PhoRpp29, and PhoRpp30) in the hyperthermophilic archaeon Pyrococcus horikoshii OT3 reconstituted RNase P activity that exhibits enzymatic properties like those of the authentic enzyme. In present study, we investigated involvement of the individual proteins in RNase P activity. Two particles (R-3Ps), in which pRNA was mixed with three proteins, PhoPop5, PhoRpp30, and PhoRpp38 or PhoPop5, PhoRpp30, and PhoRpp21 showed a detectable RNase P activity, and five reconstituted particles (R-4Ps) composed of pRNA and four proteins exhibited RNase P activity, albeit at reduced level compared to that of the reconstituted particle (R-5P) composed of pRNA and five proteins. Time-course analysis of the RNase P activities of R-4Ps indicated that the R-4Ps lacking PhoPop5, PhoRpp21, or PhoRpp30 had virtually reduced activity, while omission of PhoRpp29 or PhoRpp38 had a slight effect on the activity. The results indicate that the proteins contribute to RNase P activity in order of PhoPop5 > PhoRpp30 > PhoRpp21 > PhoRpp29 > PhoRpp38. It was further found that R-4Ps showed a characteristic Mg2+ ion dependency approximately identical to that of R-5P. However, R-4Ps had optimum temperature of around at 55 degrees C which is lower than 70 degrees C for R-5P. Together, it is suggested that the P. horikoshii RNase P proteins are predominantly involved in optimization of the pRNA conformation, though they are individually dispensable for RNase P activity in vitro.

  9. OT2_eegami_6: SPIRE Snapshot Survey II: Using SPT/CODEX Massive Clusters as Powerful Gravitational Lenses

    NASA Astrophysics Data System (ADS)

    Egami, E.

    2011-09-01

    On the extragalactic side, one of the most remarkable results coming out of Herschel is the discovery of extremely bright (>100 mJy in the SPIRE bands) gravitationally lensed galaxies. The great sensitivity and mapping speed of SPIRE have enabled us to find these rare extraordinary objects. What is truly exciting about these bright lensed galaxies is that they enable a variety of detailed multi-wavelength follow-up observations, shedding new light on the physical properties of these high-redshift sources. In this regard, our OT1 program, "SPIRE Snapshot Survey of Massive Galaxy Clusters" turned out to be a great success. After imaging ~50 galaxies out of 279 in the program, we have already found two spectacularly bright lensed galaxies, one of which is at a redshift of 4.69. This type of cluster-lensed sources are not only bright but also spatially stretched over a large scale, so ALMA (or NOEMA in the north) is likely to be able to study them at the level of individual GMCs. Such studies will open up a new frontier in the study of high-redshift galaxies. Here, we propose to extend this highly efficient and effective survey of gravitationally lensed galaxies to another 353 clusters carefully chosen from the SPT and CODEX cluster samples. These samples contain newly discovered high-redshift (z>0.3) massive (>3-4e14 Msun) clusters, which can be used as powerful gravitational lenses to magnify sources at high redshift. With the OT1 and OT2 surveys together, we expect to find ~20 highly magnified SPIRE sources with exceptional brightnesses (assuming a discovery rate of ~1/30). Such a unique sample of extraordinary objects will enable a variety of follow-up sciences, and will therefore remain as a great legacy of the Herschel mission for years to come.

  10. Remote Sensing of Global Fire Patterns, Aerosol Optical Thickness, and Carbon Monoxide During April 1994

    NASA Technical Reports Server (NTRS)

    Christopher, Sundar A.; Wang, Min; Klich, Donna V.; Welch, Ronald M.; Nolf, Scott; Connors, Vickie S.

    1997-01-01

    Fires play a crucial role in several ecosystems. They are routinely used to burn forests in order to accommodate the needs of the expanding population, clear land for agricultural purposes, eliminate weeds and pests, regenerate nutrients in grazing and crop lands and produce energy for cooking and heating purposes. Most of the fires on earth are related to biomass burning in the tropics, although they are not confined to these latitudes. The boreal and tundra regions also experience fires on a yearly basis. The current study examines global fire patterns, Aerosol Optical Thickness (AOT) and carbon monoxide concentrations during April 9-19, 1994. Recently, global Advanced Very High Resolution Radiometer (AVHRR) data at nadir ground spatial resolution of 1 km are made available through the NASA/NOAA Pathfinder project. These data from April 9-19, 1994 are used to map fires over the earth. In summary, our analysis shows that fires from biomass burning appear to be the dominant factor for increased tropospheric CO concentrations as measured by the MAPS. The vertical transport of CO by convective activities, along with horizontal transport due to the prevailing winds, are responsible for the observed spatial distribution of CO.

  11. Mount Saint Helens aerosol evolution

    NASA Technical Reports Server (NTRS)

    Oberbeck, V. R.; Farlow, N. H.; Snetsinger, K. G.; Ferry, G. V.; Fong, W.; Hayes, D. M.

    1982-01-01

    Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mt. St. Helens. Analysis of samples shows that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months.

  12. INDOOR AEROSOLS AND EXPOSURE ASSESSMENT

    EPA Science Inventory

    This chapter provides an overview of both indoor aerosol concentration measurements, and the considerations for assessment of exposure to aerosols in non-occupational settings. The fixed-location measurements of concentration at an outdoor location, while commuting inside an a...

  13. Aerosol Variability Observed with Rpas

    NASA Astrophysics Data System (ADS)

    Altstädter, B.; Lampert, A.; Scholtz, A.; Bange, J.; Platis, A.; Hermann, M.; Wehner, B.

    2013-08-01

    To observe the origin, vertical and horizontal distribution and variability of aerosol particles, and especially ultrafine particles recently formed, we plan to employ the remotely piloted aircraft system (RPAS) Carolo-P360 "ALADINA" of TU Braunschweig. The goal of the presented project is to investigate the vertical and horizontal distribution, transport and small-scale variability of aerosol particles in the atmospheric boundary layer using RPAS. Two additional RPAS of type MASC of Tübingen University equipped with turbulence instrumentation add the opportunity to study the interaction of the aerosol concentration with turbulent transport and exchange processes of the surface and the atmosphere. The combination of different flight patterns of the three RPAS allows new insights in atmospheric boundary layer processes. Currently, the different aerosol sensors are miniaturized at the Leibniz Institute for Tropospheric Research, Leipzig and together with the TU Braunschweig adapted to fit into the RPAS. Moreover, an additional meteorological payload for measuring temperature, humidity and turbulence properties is constructed by Tübingen University. Two condensation particle counters determine the total aerosol number with a different lower detection threshold in order to investigate the horizontal and vertical aerosol variability and new particle formation (aerosol particles of some nm diameter). Further the aerosol size distribution in the range from about 0.300 to ~5 μm is given by an optical particle counter.

  14. Aerosol in the Pacific troposphere

    NASA Technical Reports Server (NTRS)

    Clarke, Antony D.

    1989-01-01

    The use of near real-time optical techniques is emphasized for the measurement of mid-tropospheric aerosol over the Central Pacific. The primary focus is on measurement of the aerosol size distribution over the range of particle diameters from 0.15 to 5.0 microns that are essential for modeling CO2 backscatter values in support of the laser atmospheric wind sounder (LAWS) program. The measurement system employs a LAS-X (Laser Aerosol Spectrometer-PMS, Boulder, CO) with a custom 256 channel pulse height analyzer and software for detailed measurement and analysis of aerosol size distributions. A thermal preheater system (Thermo Optic Aerosol Descriminator (TOAD) conditions the aerosol in a manner that allows the discrimination of the size distribution of individual aerosol components such as sulfuric acid, sulfates and refractory species. This allows assessment of the relative contribution of each component to the BCO2 signal. This is necessary since the different components have different sources, exhibit independent variability and provide different BCO2 signals for a given mass and particle size. Field activities involve experiments designed to examine both temporal and spatial variability of these aerosol components from ground based and aircraft platforms.

  15. Mount St. Helens aerosol evolution

    SciTech Connect

    Oberbeck, V.R.; Farlow, N.H.

    1982-08-01

    Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mount St. Helens. Analysis of samples shows that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months.

  16. Mount St. Helens aerosol evolution

    SciTech Connect

    Oberbeck, V.R.; Farlow, N.H.; Fong, W.; Snetsinger, K.G.; Ferry, G.V.; Hayes, D.M.

    1982-09-01

    Stratospheric aerosol samples were collected using a wire impactor during the year following the eruption of Mt. St. Helens. Analysis of samples show that aerosol volume increased for 6 months due to gas-to-particle conversion and then decreased to background levels in the following 6 months.

  17. Sampling stratospheric aerosols with impactors

    NASA Technical Reports Server (NTRS)

    Oberbeck, Verne R.

    1989-01-01

    Derivation of statistically significant size distributions from impactor samples of rarefield stratospheric aerosols imposes difficult sampling constraints on collector design. It is shown that it is necessary to design impactors of different size for each range of aerosol size collected so as to obtain acceptable levels of uncertainty with a reasonable amount of data reduction.

  18. Aerosol Remote Sensing

    NASA Technical Reports Server (NTRS)

    Lenoble, Jacqueline (Editor); Remer, Lorraine (Editor); Tanre, Didier (Editor)

    2012-01-01

    This book gives a much needed explanation of the basic physical principles of radia5tive transfer and remote sensing, and presents all the instruments and retrieval algorithms in a homogenous manner. For the first time, an easy path from theory to practical algorithms is available in one easily accessible volume, making the connection between theoretical radiative transfer and individual practical solutions to retrieve aerosol information from remote sensing. In addition, the specifics and intercomparison of all current and historical methods are explained and clarified.

  19. A novel ultrasonic aerosol generator.

    PubMed

    Davies, A; Hudson, N; Pirie, L

    1995-07-01

    An ultrasonic aerosol generator constructed from a domestic humidifier is described which has been used to produce liquid aerosols for physiological investigations. The instrument was constructed from a Pifco domestic humidifier modified to include an energy guide to direct the oscillations of the transducer through the coupling water, which would normally be aerosolized, onto a small membrane based sample chamber containing the liquid to be aerosolized. The size distribution of the aerosol produced was found to be between 2 and 6 mm, optimum for diffuse intrapulmonary deposition. Up to 4 ml/min of aqueous liquid was used; however the sample chamber could be made small enough to contain economic amounts of expensive material to administer by inhalation. The instrument has proved to be reliable over a period of three years.

  20. The Aerosol Coarse Mode Initiative

    NASA Astrophysics Data System (ADS)

    Arnott, W. P.; Adhikari, N.; Air, D.; Kassianov, E.; Barnard, J.

    2014-12-01

    Many areas of the world show an aerosol volume distribution with a significant coarse mode and sometimes a dominant coarse mode. The large coarse mode is usually due to dust, but sea salt aerosol can also play an important role. However, in many field campaigns, the coarse mode tends to be ignored, because it is difficult to measure. This lack of measurements leads directly to a concomitant "lack of analysis" of this mode. Because, coarse mode aerosols can have significant effects on radiative forcing, both in the shortwave and longwave spectrum, the coarse mode -- and these forcings -- should be accounted for in atmospheric models. Forcings based only on fine mode aerosols have the potential to be misleading. In this paper we describe examples of large coarse modes that occur in areas of large aerosol loading (Mexico City, Barnard et al., 2010) as well as small loadings (Sacramento, CA; Kassianov et al., 2012; and Reno, NV). We then demonstrate that: (1) the coarse mode can contribute significantly to radiative forcing, relative to the fine mode, and (2) neglecting the coarse mode may result in poor comparisons between measurements and models. Next we describe -- in general terms -- the limitations of instrumentation to measure the coarse mode. Finally, we suggest a new initiative aimed at examining coarse mode aerosol generation mechanisms; transport and deposition; chemical composition; visible and thermal IR refractive indices; morphology; microphysical behavior when deposited on snow and ice; and specific instrumentation needs. Barnard, J. C., J. D. Fast, G. Paredes-Miranda, W. P. Arnott, and A. Laskin, 2010: Technical Note: Evaluation of the WRF-Chem "Aerosol Chemical to Aerosol Optical Properties" Module using data from the MILAGRO campaign, Atmospheric Chemistry and Physics, 10, 7325-7340. Kassianov, E. I., M. S. Pekour, and J. C. Barnard, 2012: Aerosols in Central California: Unexpectedly large contribution of coarse mode to aerosol radiative forcing

  1. Purification, crystallization and preliminary crystallographic analysis of RecA superfamily ATPase PH0284 from Pyrococcus horikoshii OT3

    SciTech Connect

    Bagautdinov, Bagautdin; Kunishima, Naoki

    2006-04-01

    RecA superfamily ATPase PH0284 from P. horikoshii OT3 was overexpressed, purified, crystallized and cocrystallized with ATP. Both crystal forms belong to the trigonal space group P3{sub 2}21 and diffract X-rays to 2.0 and 2.3 Å resolution, respectively. Circadian (daily) protein clocks are found in cyanobacteria, where a complex of the KaiA, KaiB and KaiC proteins generates circadian rhythms. The 28.09 kDa KaiC homologue PH0284 protein from Pyrococcus horikoshii OT3 was cloned and expressed and the purified protein was crystallized by the oil-microbatch method at 295 K. X-ray diffraction data from the crystal were collected to 2.0 Å resolution using synchrotron radiation at 100 K. The crystal belongs to the trigonal space group P3{sub 2}21, with unit-cell parameters a = b = 96.06, c = 298.90 Å. Assuming the presence of one hexamer in the asymmetric unit gives a V{sub M} value of 2.36 Å{sup 3} Da{sup −1} and a solvent content of 47.9%. A cocrystal with ATP was prepared and a diffraction data set was collected at 2.3 Å resolution.

  2. Mechanistic basis for high reactivity of (salen)Co-OTs in the hydrolytic kinetic resolution of terminal epoxides.

    PubMed

    Nielsen, Lars P C; Zuend, Stephan J; Ford, David D; Jacobsen, Eric N

    2012-03-02

    The (salen)Co(III)-catalyzed hydrolytic kinetic resolution (HKR) of terminal epoxides is a bimetallic process with a rate controlled by partitioning between a nucleophilic (salen)Co-OH catalyst and a Lewis acidic (salen)Co-X catalyst. The commonly used (salen)Co-OAc and (salen)Co-Cl precatalysts undergo complete and irreversible counterion addition to epoxide during the course of the epoxide hydrolysis reaction, resulting in quantitative formation of weakly Lewis acidic (salen)Co-OH and severely diminished reaction rates in the late stages of HKR reactions. In contrast, (salen)Co-OTs maintains high reactivity over the entire course of HKR reactions. We describe here an investigation of catalyst partitioning with different (salen)Co-X precatalysts and demonstrate that counterion addition to epoxide is reversible in the case of the (salen)Co-OTs. This reversible counterion addition results in stable partitioning between nucleophilic and Lewis acidic catalyst species, allowing highly efficient catalysis throughout the course of the HKR reaction.

  3. Mechanistic Basis for High Reactivity of (salen)Co–OTs in the Hydrolytic Kinetic Resolution of Terminal Epoxides

    PubMed Central

    Nielsen, Lars P. C.; Zuend, Stephan J.; Ford, David D.; Jacobsen, Eric N.

    2012-01-01

    The (salen)Co(III)-catalyzed hydrolytic kinetic resolution (HKR) of terminal epoxides is a bimetallic process with a rate controlled by partitioning between a nucleophilic (salen)Co–OH catalyst and a Lewis acidic (salen)Co–X catalyst. The commonly used (salen)Co–OAc and (salen)Co–Cl precatalysts undergo complete and irreversible counterion addition to epoxide during the course of the epoxide hydrolysis reaction, resulting in quantitative formation of weakly Lewis acidic (salen)Co–OH, and severely diminished reaction rates in the late stages of HKR reactions. In contrast, (salen)Co–OTs maintains high reactivity over the entire course of HKR reactions. We describe here an investigation of catalyst partitioning with different (salen)Co–X precatalysts, and demonstrate that counterion addition to epoxide is reversible in the case of the (salen)Co–OTs. This reversible counterion addition results in stable partitioning between nucleophilic and Lewis acidic catalyst species, allowing highly efficient catalysis throughout the course of the HKR reaction. PMID:22292515

  4. Purification, crystallization and initial X-ray crystallographic analysis of the putative GTPase PH0525 from Pyrococcus horikoshii OT3

    SciTech Connect

    Lokanath, Neratur K.; Yamamoto, Hitoshi; Matsunaga, Emiko; Sugahara, Mitsuaki; Kunishima, Naoki

    2005-10-01

    The putative GTPase PH0525 from P. horikoshii OT3 was crystallized using the microbatch method. Crystals were formed under two different conditions, providing two distinct crystal forms. Diffraction data from the two forms were measured to resolution limits of 2.30 and 2.40 Å and processed in space groups P2{sub 1} and C222{sub 1}, respectively. GTPases are involved in diverse cellular functions including cell proliferation, cytoskeleton organization and intracellular traffic. The putative GTPase PH0525 from Pyrococcus horikoshii OT3 has been overexpressed in Escherichia coli and purified. Two distinct crystal forms were grown by the microbatch method at 291 K using a very high protein concentration (80 mg ml{sup −1}). Native data sets extending to resolutions of 2.3 and 2.4 Å have been collected and processed in space groups P2{sub 1} and C222{sub 1}, respectively. Assuming the presence of one monomer per asymmetric unit gives V{sub M} values of 2.6 and 2.4 Å{sup 3} Da{sup −1} for the P2{sub 1} and C222{sub 1} forms, respectively, which is consistent with dynamic light-scattering experiments, which show a monomeric state of the protein in solution.

  5. NGC 300 OT2008-1 as a Scaled-down Version of the Eta Carinae Great Eruption

    NASA Astrophysics Data System (ADS)

    Kashi, Amit; Frankowski, Adam; Soker, Noam

    2010-01-01

    We propose that the intermediate luminosity optical transient NGC 300 OT2008-1 was powered by a mass transfer episode from an extreme asymptotic giant branch star to a main sequence (MS) companion. We find a remarkable similarity in the shapes of the light curves of the several months long NGC 300 OT2008-1 outburst, of the three-month long 2002 enigmatic outburst of the B star V838 Mon, and the twenty-year long Great Eruption of the massive binary system Eta Carinae that occurred in the 19th century. Their similar decline properties hint to a common energy source: a gravitational energy that is released by accretion onto an MS star. These events populate a specific strip in the total energy versus outburst duration diagram. The strip is located between novae and supernovae. We add recent transient events to that diagram and find them to occupy the same strip. This suggests that some intermediate luminosity optical transients are powered by accretion onto a compact object (not necessarily an MS star). These transients are expected to produce bipolar ejecta as a result of the geometry of the accretion process.

  6. Overproduction and preliminary crystallographic study of a human kynurenine aminotransferase II homologue from Pyrococcus horikoshii OT3

    SciTech Connect

    Chon, Hyongi; Matsumura, Hiroyoshi; Shimizu, Shoko; Maeda, Nao; Koga, Yuichi; Takano, Kazufumi; Kanaya, Shigenori

    2005-03-01

    A human kynurenine aminotransferase II homologue from P. horikoshii OT3 has been overproduced in E. coli, purified, and characterized. Crystals of this protein have been obtained and analyzed by X-ray diffraction. The Pyrococcus horikoshii OT3 genome contains a gene encoding a human kynurenine aminotransferase II (KAT II) homologue, which consists of 428 amino-acid residues and shows an amino-acid sequence identity of 30% to human KAT II. This gene was overexpressed in Escherichia coli and the recombinant protein (Ph-KAT II) was purified. Gel-filtration chromatography showed that Ph-KAT II exists as a homodimer. Ph-KAT II exhibited enzymatic activity that catalyzes the transamination of l-kynurenine to produce kynurenic acid. Crystals of Ph-KAT II were grown using the sitting-drop vapour-diffusion method and native X-ray diffraction data were collected to 2.2 Å resolution using synchrotron radiation from station BL44XU at SPring-8. The crystals belong to the centred orthorhombic space group C222{sub 1}, with unit-cell parameters a = 71.75, b = 86.84, c = 137.30 Å. Assuming one molecule per asymmetric unit, the V{sub M} value was 2.19 Å{sup 3} Da{sup −1} and the solvent content was 43.3%.

  7. A procedure for the joint evaluation of substrate partitioning and kinetic parameters for reactions catalyzed by enzymes in reverse micellar solutions. I. Hydrolysis of 2-naphthyl acetate catalyzed by lipase in sodium 1,4-bis(2-ethylhexyl) sulphosuccinate (AOT)/buffer/heptane.

    PubMed

    Aguilar, L F; Abuin, E; Lissi, E

    2001-04-15

    A simple method useful for the joint evaluation of substrate partitioning and kinetic parameters for reactions catalyzed by enzymes entrapped in reverse micelles is proposed. The method is applied to the hydrolysis of 2-naphthyl acetate (2-NA) catalyzed by lipase in sodium 1,4-bis(2-ethylhexyl) sulfosuccinate (AOT)/buffer/heptane reverse micellar solutions. In the presence of micelles, the relationship between the initial reaction rate and the analytical concentration of 2-NA was dependent on AOT concentration at a constant W ([water]/[AOT]) value. The dependence of the initial reaction rate profiles with [AOT] was analyzed according with the method proposed to obtain the partition constant of 2-NA between the micelles and the external solvent, Kp. A value of Kp = 2.7 L mol(-1) was obtained irrespective of the water content of the micelles (W from 5 to 20). The catalytic rate constant kcat in the micellar solutions was independent of [AOT] but slightly decreased with an increase in W from 2 x 10(-6) mol g(-1) s(-1) at W = 5 to 1.2 x 10(-6) mol g(-1) s(-1) at W = 20. The apparent Michaelis constant determined in terms of the analytical concentration of 2-NA increased with [AOT] at a given W and moderately decreased with W at a fixed [AOT]. The increase with [AOT] is ac