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  • 1
    Electronic Resource
    Electronic Resource
    Adaptive significance of furanocoumarin diversity inPastinaca sativa (Apiaceae) (1991)
    Springer
    Journal of chemical ecology 17 (1991), S. 207-215 
    Details
    ISSN: 1573-1561
    Keywords: Heliothis zea ; corn earworm ; Lepidoptera ; Noctuidae ; Pastinaca sativa ; wild parsnip ; Apiaceae ; furanocoumarins ; defense ; xanthotoxin ; photoactivation ; bioassay
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Fruits ofPastinaca sativa (Apiaceae), the edible parsnip, contain six different furanocoumarins that are differentially capable of ultraviolet-mediated cross-linkage of DNA and inhibition of DNA transcription. Individually, none of the other furanocoumarins present in parsnip seeds is as toxic as the photosensitizer xanthotoxin. Nevertheless, the natural mixture of compounds is toxicologically more effective againstHeliothis zea (Lepidoptera: Noctuidae), both in the presence and absence of UV light, than is an equimolar amount of xanthotoxin. The difference in toxicity diminishes with increasing light levels. Thus, a series of structurally related natural products can display toxicity lacking in individual compounds and may represent an adaptive compromise to varying environmental conditions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00994434
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Stratospheric ozone depletion and plantinsect interactions: Effects of UVB radiation on foliage quality ofCitrus jambhiri forTrichoplusia ni (1994)
    Springer
    Journal of chemical ecology 20 (1994), S. 525-539 
    Details
    ISSN: 1573-1561
    Keywords: Citrus jambhiri ; Trichoplusia ni ; Lepidoptera ; Noctuidae ; bergapten ; furanocoumarins ; phototoxins ; plant-herbivore interactions ; psoralen ; ultraviolet-B radiation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Projected decreases in stratospheric ozone may result in increases in shortwave ultraviolet (UVB) irradiation at the earth's surface. Furanocoumarins, phototoxic compounds found inCitrus jambhiri foliage, increase in concentration when these plants are grown under enhanced UVB. Survivorship schedules ofTrichoplusia ni (Lepidoptera: Noctuidae) caterpillars reared on plants in the presence and absence of enhanced UVB regimes differ significantly; larvae develop more slowly in early life when reared on plants exposed to increased UVB. This same developmental pattern is observed whenT. ni larvae are reared on artificial diets amended with ecologically appropriate amounts of furanocoumarins. Thus, anthropogenically derived changes in stratospheric ozone and concomitant changes in UV light quality at the earth's surface may influence ecological interactions between insects and their host plants by altering secondary metabolism and hence foliage quality for herbivores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02059595
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  • 3
    Electronic Resource
    Electronic Resource
    Leaf-tying by tortricid larvae as an adaptation for feeding on phototoxicHypericum perforatum (1989)
    Springer
    Journal of chemical ecology 15 (1989), S. 875-885 
    Details
    ISSN: 1573-1561
    Keywords: Hypericum perforatum ; phototoxicity ; hypericism ; Platynota flavedana ; Tortricidae ; Heliothis zea ; Noctuidae ; Lepidoptera
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Hypericin, an anthrone dimer inHypericum perforatum (Guttiferae), is shown for the first time to be phototoxic to generalist lepidopteran larvae; survivorship was reduced and development prolonged forHeliothis zea (Noctuidae) andPlatynota flavedana (Tortricidae) that consumed hypericin diets in the presence of light. Survivorship for both species is enhanced when photoactivating wavelengths are excluded by filters. In natureP. flavedana successfully survives onH. perforatum by tying together leaves and feeding inside the ties. Shielded from light, the larvae are protected by their mode of feeding from phototoxic compounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01015183
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  • 4
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    In situ measurements of the NO2/NO ratio for testing atmospheric photochemical models (1994)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Simultaneous in situ measurements of NO2, NO, O3, ClO, pressure and temperature have been made for the first time, presenting a unique opportunity to test our current understanding of the photochemistry of the lower stratospere. Data were collected from several flights of the ER-2 aircraft at mid-latitudes in May 1993 during NASA's Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE). The daytime ratio of NO2/NO remains fairly constant at 19 km with a typical value of 0.68 and standard deviation of +/- 17. The ratio observations are compared with simple steady-state calculations based on laboratory-measured reaction rates and modeled NO2 photolysis rates. At each measurement point the daytime NO2/NO with its measurements uncertainty overlap the results of steady-state caculations and associated uncertainty. Possible sources of error are examined in both model and measurements. It is shown that more accurate laboratory determinations of the NO + 03 reaction rate and of the NO2 cross-sections in the 200-220 K temperature range characteristic of the lower stratosphere would allow for a more robust test of our knowledge of NO(X) phtochemistry by reducing significant sources if uncertainties in the interpretation of statospheric measurements.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 23; p. 2555-2558
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  • 5
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    Chlorine chemistry on polar stratospheric cloud particles in the Arctic winter (1993)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Simultaneous in situ measurements of hydrochloric acid (HCl) and chlorine monoxide (ClO) in the Arctic winter vortex showed large HCl losses of up to 1 ppbv, which were correlated with high ClO levels of up to 1.4 ppbv. Air parcel trajectory analysis identified that this conversion of inorganic chlorine occurred at air temperatures of less than 196 -/+ 4 kelvin. High ClO was always accompanied by loss of HCl mixing ratios equal to 1/2(ClO+ 2Cl2O2). These data indicate that the heterogeneous reaction HCl + ClONO2 - Cl2 + HNO3 on particles of polar stratospheric clouds establishes the chlorine partitioning, which, contrary to earlier notions, begins with an excess of ClONO2, not HCl.
    Keywords: GEOPHYSICS
    Type: Science (ISSN 0036-8075); 261; 5125; p. 1130-1134.
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  • 6
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    The BLISS measurements of NO2 - Some new insights (1991)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: The present study compares the diurnal variation of NO2 measured near 30 km by the BLISS in situ laser spectrometer with calculations from a photochemical model that includes a detailed description of multiple scattering. Even better agreement is found between the data and the model, both at sunset and during the day. The conclusions of an earlier study that the high-resolution in situ measurements of NO2 facilitated validation of the understanding of the diurnal chemistry of NO2 are confirmed.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 18; 2261-226
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  • 7
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    Laboratory measurements of NO2 line parameters near 1600/cm for the interpretation of stratospheric spectra (1990)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Tunable diode laser laboratory measurements of infrared spectral parameters of selected NO2 lines near 1600/cm have been made to assess the contribution of uncertainties in these parameters to stratospheric measurements of NO2 made using the Balloon-Borne Laser In-Situ Sensor (BLISS) tunable diode laser spectrometer. Relative line intensities are measured to accuracies of better than 2 percent, with a root-sum-squared uncertainty in the absolute linestrengths of 4.5 percent. Air-broadening coefficients have been determined from measurements at total pressures in the range 20-100 Torr, at temperatures of 293 K and 214 K. These results are also discussed in the light of the discrepancies between infrared instruments flown in the 1982 and 1983 Balloon Intercomparison Campaigns.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 17; 2157-216
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  • 8
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    Theoretical interpretation of N2O5 measurements (1991)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: Recent measurements by Webster et al. (1990) have confirmed quantitatively the chemistry controlling the nighttime decay of NO2. Simple equations describing the nighttime behavior of NO2 and N2O5 are presented here. With measurements of the nighttime ozone and NO2 concentrations, these equations can be used to predict the amount of N2O5 produced at any time during the night. In this way, the N2O5 nighttime emission measurement of Roscoe (1982), Kunde et al. (1988) and sunrise measurements of the ATMOS experiment are all used to test theory. The measurements are found to be both self consistent and confirm the present understanding of nighttime NO2 conversion to N2O5. The variation of N2O5 by a factor of two between measurements is found to be consistent with theory.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 18; 1213-121
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  • 9
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    In situ stratospheric measurements of HNO3 and HCl near 30 km using the balloon-borne laser in situ sensor tunable diode laser spectrometer (1989)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Description: In situ stratospheric measurements of the concentrations of the reservoir species HNO3 and HCl made during two flights of the high-resolution (0.0005/cm) balloon-borne laser in situ sensor instrument from Palestine, Texas, are reported. A measured HNO3 volume mixing ratio of 4.3 parts per billion by volume (ppbv) at 31 km altitude is about 1 ppbv larger than previously reported measurements at 32 deg N. An HCl mixing ratio of 1.6 ppbv at 29 km is in agreement with values obtained from earlier remote sensing techniques within the experimental uncertainties. Upper limits at 31 km of 0.4 ppbv for H2O2 and 0.2 ppbv for HOCl are also derived from analyses of spectra recorded near 1252/cm.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 94; 16343-16
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  • 10
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    An examination of the total hydrogen budget of the lower stratosphere (1994)
    In:  Other Sources
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    Publication Date: 2019-07-13
    Description: We analyze the hydrogen budget of the lower stratosphere using simultaneous in situ measurements of northern hemispheric water vapor (H2O) and methane (CH4) obtained during the spring Stratospheric Photochemistry, Aerosols, and Dynamics Expedition (SPADE), as well as previously published in situ H2 data. Based on this data, we conclude that approximately two H2O molecules are produced for each CH4 molecule destroyed. This implies that H2 production from CH4 oxidation is balanced by H2 oxidation. The uncertainty in this analysis is greatly reduced by the use of multiple data sets. Additionally, we infer that, on an annual and global average, H2O enters the stratosphere with a mixing ratio of 4.2 +/- 0.5 ppmv, and that the quasi-conserved quantity 2 x CH4 + H2O has a value of 7.6 +/- 0.6 ppmv in these northern hemishere air parcels (where xi denotes the mixing ratio of the constituent xi).
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 23; p. 2563-2566
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