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  • 1
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    Highly Efficient Oxidative Desulfuri-zation of Fuels by Lewis Acidic Ionic Liquids Based on Iron Chloride (2013)
    Wiley
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    Publikationsdatum: 2013-02-07
    Beschreibung: Acidic ionic liquids (ILs) have been employed as extractant and catalyst in the oxidative desulfurization (ODS) process of fuels in recent years. Several Lewis acidic ionic liquids [C 6 3 MPy]Cl/ n FeCl 3 (molar fraction n = 0.5, 1, 2, 3) and [C 6 MIM]Cl/FeCl 3 were prepared and used to remove the aromatic sulfur compounds dibenzothiophene and benzothiophene from fuels. In the ODS process, the used ILs acted as both extractant and catalyst with 30 wt % hydrogen peroxide aqueous solution as oxidant. The effects of Lewis acidity of ILs, IL's cation structure, molar ratio of O/S, reaction temperature, and different sulfur compounds on the sulfur removal of model oil were investigated. The results indicated that the sulfur removal for dibenzothiophene was affected by Lewis acidity of ILs and nearly reached 100 % by [C 6 3 MPy]Cl/FeCl 3 at conditions of 298 K, IL/oil mass ratio of 1/3, O/S molar ratio of 4/1, in 20 min. The sulfur removal of real gasoline reached 99.7 % after seven ODS runs in the [C 6 3 MPy]Cl/FeCl 3 -H 2 O 2 system. The oxidative desulfurization process of fuels using ionic liquids (ILs) was studied. Lewis acidic ILs acted as both extractant and catalyst in the removal of dibenzothio-phene and benzothiophene with 30 wt % hydrogen peroxide aqueous solution as oxidant. The effects of different reaction parameters such as Lewis acidity, cation structure, and reaction temperature on the sulfur removal were investigated.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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  • 2
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    The spatial distribution of planetary ion fluxes near Mars observed by MAVEN (2015)
    Wiley
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    Publikationsdatum: 2015-11-06
    Beschreibung: We present the results of an initial effort to statistically map the fluxes of planetary ions on a closed surface around Mars. Choosing a spherical shell ~1000 km above the planet, we map both outgoing and incoming ion fluxes (with energies 〉25 eV) over a 4 month period. The results show net escape of planetary ions behind Mars and strong fluxes of escaping ions from the northern hemisphere with respect to the solar wind convection electric field. Planetary ions also travel toward the planet, and return fluxes are particularly strong in the southern electric field hemisphere. We obtain a lower bound estimate for planetary ion escape of ~3 × 10 24  s −1 , accounting for the ~10% of ions that return toward the planet and assuming that the ~70% of the surface covered so far is representative of the regions not yet visited by Mars Atmosphere and Volatile EvolutioN (MAVEN).
    Print ISSN: 0094-8276
    Digitale ISSN: 1944-8007
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 3
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    Catalytically Assisted Methane Combustion over a Platinum Gauze: Species Profile Measurements, Laser Induced Fluorescence Spectroscopy and Reactor Simulations (2016)
    Wiley
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    Publikationsdatum: 2016-07-22
    Beschreibung: Profile measurements in a catalytic gauze reactor are conducted for catalytically assisted methane combustion over platinum. The reactor combines a capillary sampling technique with a novel fiber-optic Laser-Induced Fluorescence (LIF) Spectroscopy method for detection and quantification of gas phase OH[[[Wingdings;F09E]]] radicals serving as indicator species for gas phase reactions. The steep spatial gradients in the vicinity of the gauze are resolved at submillimeter scale. Experimental profiles are compared with three dimensional numerical reactor simulations including flow, mass transport, heat transport and microkinetic models for both surface and gas phase chemistry. The results provide insight into the interaction of chemistry and transport upstream, at and downstream the catalytic gauze and the interaction of surface and gas phase reactions by exchange of heat and radicals released from the catalyst surface.
    Print ISSN: 0930-7516
    Digitale ISSN: 1521-4125
    Thema: Chemie und Pharmazie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Publiziert von Wiley
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  • 4
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    O+ ion beams reflected below the Martian bow shock: MAVEN observations (2016)
    Wiley
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    Publikationsdatum: 2016-03-24
    Beschreibung: We investigate a generation mechanism of O + ion beams observed above the Martian bow shock by analyzing ion velocity distribution functions (VDFs) measured by the Superthermal and Thermal Ion Composition (STATIC) instrument on the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. In the solar wind near Mars, MAVEN often observes energetic O + ion beams (~10 keV or higher). Accompanied with the O + ion beam events, we sometimes observe characteristic ion VDFs in the magnetosheath: a partial ring distribution. The partial ring distribution corresponds to pickup ions with a finite initial velocity (i.e. not newborn pickup ions), and its phase space density is much smaller than that of local pickup O + ions of the magnetosheath. Thus the partial ring distribution is most likely produced by the reflection of pickup O + ions precipitating from the upstream solar wind below the bow shock. After being injected into the magnetosheath from the solar wind, the precipitating O + ions are subject to the significantly enhanced magnetic field in this region and start to gyrate around the guiding center of the plasma frame in the magnetosheath. Consequently, a part of precipitating O + ions are reflected back to the solar wind, generating O + beams in the solar wind. The beams direct quasi-sunward near the subsolar region but have large angle with respect to the sunward direction at high solar zenith angles (〉50°). The reflected O + beams are accelerated by the convection electric field of the solar wind and may escape Mars.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 5
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    Influence of Extreme Ultraviolet Irradiance Variations on the Precipitating Ion Flux From MAVEN Observations (2019)
    Wiley
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    Publikationsdatum: 2019
    Beschreibung: Abstract We study the influence of the solar extreme ultraviolet (EUV) flux intensity on the precipitating ion fluxes as seen by the Solar Wind Ion Analyzer, an energy and angular ion spectrometer aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft. We defined three periods with significantly different EUV flux intensity (1.6 and 3.2 times the lowest EUV intensity) and compare the precipitating ion flux measured by MAVEN/Solar Wind Ion Analyzer during each period. At low energy [30–650] eV, we find that the median (average) precipitating ion flux during the medium and low EUV periods are, respectively, 1.7 (2.1) and 3 (3.5) times more intense than the flux during the high EUV period. At high energy [650–25,000] eV, a similar trend in the intensity of the precipitating ion flux is observed but with an increase by 50% (46%) and 70% (79%), respectively. A larger EUV flux does therefore not seem to favor heavy ion precipitation into Mars's atmosphere, contrary to modeling prediction and overall expectations.
    Print ISSN: 0094-8276
    Digitale ISSN: 1944-8007
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 6
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    Cellular and molecular mechanisms of silibinin induces cell-cycle arrest and apoptosis on HeLa cells (2012)
    Wiley
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    Publikationsdatum: 2012-04-15
    Beschreibung: Silibinin, an effective anti-cancer and chemopreventive agent in various epithelial cancer models, has been reported to inhibit cancer cell growth through mitogenic signalling pathways including cervical cancer. However, the underlying mechanisms are still not well elucidated. Here, we assessed the effect of silibinin on human cervical carcinoma cell cycle modulation, apoptosis induction and associated molecular alterations by employing HeLa cell line. Silibinin treatment of HeLa cells resulted in a G2 arrest and induced a decrease in cyclin-dependent kinases involved in both G1 and G2 progression. In addition, silibinin showed a dose-dependent and a time-dependent apoptotic death in HeLa cells in both the mitochondrial pathway and the death receptor-mediated pathway, providing a strong rationale for future studies evaluating preventive and/or intervention strategies for silibinin in cervical cancer pre-clinical models. Copyright © 2011 John Wiley & Sons, Ltd.
    Print ISSN: 0263-6484
    Digitale ISSN: 1099-0844
    Thema: Biologie , Medizin
    Publiziert von Wiley
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  • 7
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    Charged nanograins in the Enceladus plume (2012)
    Wiley
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    Publikationsdatum: 2012-05-04
    Beschreibung: There have been three Cassini encounters with the south-pole eruptive plume of Enceladus for which the Cassini Plasma Spectrometer (CAPS) had viewing in the spacecraft ram direction. In each case, CAPS detected a cold dense population of heavy charged particles having mass-to-charge (m/q) ratios up to the maximum detectable by CAPS (∼104 amu/e). These particles are interpreted as singly charged nanometer-sized water-ice grains. Although they are detected with both negative and positive net charges, the former greatly outnumber the latter, at least in the m/q range accessible to CAPS. On the most distant available encounter (E3, March 2008) we derive a net (negative) charge density of up to ∼2600 e/cm3 for nanograins, far exceeding the ambient plasma number density, but less than the net (positive) charge density inferred from the RPWS Langmuir probe data during the same plume encounter. Comparison of the CAPS data from the three available encounters is consistent with the idea that the nanograins leave the surface vents largely uncharged, but become increasingly negatively charged by plasma electron impact as they move farther from the satellite. These nanograins provide a potentially potent source of magnetospheric plasma and E-ring material.
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 8
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    Cellular and molecular mechanisms of silibinin induces cell-cycle arrest and apoptosis on HeLa cells (2012)
    Wiley
    Details
    Publikationsdatum: 2012-03-02
    Beschreibung: Silibinin, an effective anti-cancer and chemopreventive agent in various epithelial cancer models, has been reported to inhibit cancer cell growth through mitogenic signalling pathways including cervical cancer. However, the underlying mechanisms are still not well elucidated. Here, we assessed the effect of silibinin on human cervical carcinoma cell cycle modulation, apoptosis induction and associated molecular alterations by employing HeLa cell line. Silibinin treatment of HeLa cells resulted in a G2 arrest and induced a decrease in cyclin-dependent kinases involved in both G1 and G2 progression. In addition, silibinin showed a dose-dependent and a time-dependent apoptotic death in HeLa cells in both the mitochondrial pathway and the death receptor-mediated pathway, providing a strong rationale for future studies evaluating preventive and/or intervention strategies for silibinin in cervical cancer pre-clinical models. Copyright © 2011 John Wiley & Sons, Ltd.
    Print ISSN: 0263-6484
    Digitale ISSN: 1099-0844
    Thema: Biologie , Medizin
    Publiziert von Wiley
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  • 9
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    Magnetic Field in the Martian Magnetosheath and the Application as an IMF Clock Angle Proxy (2019)
    Wiley
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    Publikationsdatum: 2019
    Beschreibung: Abstract We present a study of the magnetic field in the Martian magnetosheath using data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission and provide a proxy for the upstream interplanetary magnetic field (IMF) clock angles based on the sheath field directions. The magnetic field data from MAVEN taken in the sheath region are organized in the Mars Solar Electric field coordinate system and sorted by the IMF polarity. The sheath magnetic field distributions clearly illustrate the morphology of draped IMF around the planetary obstacle and show strong asymmetries between the quasi‐perpendicular and quasi‐parallel bow shock quadrants as well as a slight asymmetry between the +E and –E quadrants. We have also studied the effects of different drivers on the strengths and clock angles of the sheath magnetic field and find that the sheath field is strongly affected by upstream IMF and solar wind and that Martian crustal fields also have small contributions to the sheath magnetic field strength. Based on the morphology of the draped field in the sheath, we developed a simple IMF clock angle proxy as the clock angle of the orbital‐averaged sheath magnetic field, which works well under steady IMF conditions. This proxy has an error 〈44° for 75% of all instances. The uncertainty of the proxy depends on upstream conditions and spacecraft orbit geometry. We also provide estimates of the proxy uncertainty based on sheath magnetic field variability and proxy clock angle.
    Print ISSN: 2169-9380
    Digitale ISSN: 2169-9402
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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  • 10
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    Characteristics of ice grains in the Enceladus plume from Cassini observations (2014)
    Wiley
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    Publikationsdatum: 2014-12-04
    Beschreibung: Ice grains in the Enceladus plume have been observed by several Cassini instruments during many Enceladus encounters. In this paper we study the ice grains ranging from ~ nm to ~ µm in size based on multiple instrument observations. We have analyzed the nanograin data from the E17 and E18 CAPS energy spectra using the approach of Hill et al. (2012), and studied the charging of the grains using the E3 - E6 RPWS-LP data presented by Morooka et al. (2011). To bridge the gap between CAPS nanograin observations and CDA and RPWS micrograin observations, we propose a composite size distribution and fit it to the E3, E5, E17 and E18 CAPS and RPWS data. The resulting size distribution peaks at ~2 nm and provides a total grain mass density ~20% that of the water vapor measured by INMS at the densest part of the plume and a total grain charge density much smaller than that inferred from the RPWS-LP plasma data. Charge balance with the RPWS-LP plasma data would require many more grains than provided by the best-fit composite distribution fitted to the CAPS and RPWS data, and would provide a grain mass density comparable to that of the water vapor. On the basis of these results, we study the subsequent motion of the ice grains and estimate the resulting grain current (~10 4 - ~10 5 A) and grain mass production rate (~15 - 65 kg/s).
    Print ISSN: 0148-0227
    Thema: Geologie und Paläontologie , Physik
    Publiziert von Wiley im Namen von American Geophysical Union (AGU).
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