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  • 1985-1989  (3)
  • 1965-1969  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Acoustic properties of proton-exchanged LiNbO3 studied using the acoustic microscopy V(z) technique (1986)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 60 (1986), S. 2517-2522 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report measurements of proton-exchanged LiNbO3 using acoustic microscopy in the V(z) mode, together with optical waveguide mode observations. In the present case, samples were prepared using dilute benzoic acid containing a small mole percent of lithium benzoate. Substantial changes in surface acoustic wave (SAW) propagation velocity due to proton exchange have been observed on all three major-axis crystal cuts, with both increase and decrease in velocity occurring, depending on propagation direction. Changes in attenuation are also observed. Using the V(z) technique with a line-focus cylindrical lens has enabled complete velocity surfaces for proton-exchanged lithium niobate to be obtained with reasonable precision, based on simplified isotropic calculations of acoustic propagation in layered media and the assumption that the proton-exchange region is uniform with a depth obtainable from optical waveguide mode calculations. It is concluded that the V(z) acoustic microscopy technique can provide a powerful tool in the study of the SAW properties of proton-exchanged LiNbO3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.337114
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A Comparison of Test Procedures for the Detection of Antibody to Borrelia burgdorferi (1988)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 539 (1988), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1988.tb31911.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Seaweed-herbivore-predator interactions: host-plant specialization reduces predation on small herbivores (1989)
    Springer
    Oecologia 81 (1989), S. 418-427 
    Details
    ISSN: 1432-1939
    Keywords: Ascoglossans ; Caphyra rotundifrons ; Chemical defense ; Chlorodesmis ; Plant-herbivore-predator interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Because feeding specialization among marine herbivores is rare, marine communities provide a simplified system for identifying factors selecting for specialization. On Australia's Great Barrier Reef, we investigated interactions among the chemically-defended seaweed Chlorodesmis fastigiata, herbivores specialized on this alga, and potential predators of these herbivores. Chlorodesmis is a low preference food for reef fishes but appears to be the only food of the crab Caphyra rotundifrons and the ascoglossan gastropods Elysia sp. and Cyerce nigricans. The crab is found only in patches of Chlorodesmis, feeds solely on the alga, and selectively shelters in it in laboratory choice experiments. Crab grazing on the red seaweed Acanthophora spicifera was stimulated when this alga was coated with increasing concentrations of the cytotoxic diterpenoid chlorodesmin, the major secondary metabolite of Chlorodesmis. Crabs did not sequester Chlorodesmis metabolites but avoided predators by sheltering in the unpalatable alga. All crabs tethered on the reef without access to Chlorodesmis patches were rapidly eaten; those with access to Chlorodesmis patches were much less susceptible to predation. The cryptic ascoglossan Elysia sp. was found exclusively in patches of Chlorodesmis and sequestered metabolites from the alga. Living Elysia were unpalatable to the common wrasse Thalassoma lunare in laboratory assays, but the crude organic extract of Elysia did not significantly deter feeding by Thalassoma. Elysia sequestered chlorodesmin, which deterred feeding by reef fishes in field assays but was ineffective against Thalassoma in laboratory assays at 5% food dry mass. Unlike Elysia, the aposematically colored ascoglossan Cyerce nigricans sequestered Chlorodesmis metabolites in relatively small amounts, but produced larger amounts of unrelated polypropionate compounds. Cyerce were never attacked by fishes and the crude organic extract of this slug strongly deterred feeding by wrasses in laboratory assays. The dorid nudibranch Gymnodoris sp. was found only in Chlorodesmis patches and appeared to be a specialized predator on Elysia; it would not prey on Cyerce. Data from this and other recent investigations demonstrate that some small marine herbivores feed selectively or exclusively on seaweeds that are chemically defended from fishes. This association reduces predation on the herbivores and suggests that escape from and deterrence of predation may be a dominant factor selecting for specialization among these herbivores.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377093
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    A comparison of new techniques for the detection and determination of triazine herbicides separated by thin-layer chromatography (1969)
    Springer
    Microchimica acta 57 (1969), S. 480-489 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Flüssigkeits-Szintillationszählung zur Bestimmung von14C-markiertem Ametryn in Dünnschichtchromatogrammen wurde eingehend geprüft. Alterung, Löschungseffekt von Trägersubstanz und Adsorptionsmitteln, Temperaturbeständigkeit der Verbindung in adsorbiertem Zustand wurden untersucht. Die Reproduzierbarkeit beträgt 1 bis 2%, die Nachweisgrenze 0,005μg pro Tüpfel, das Signal-Hintergrund-Verhältnis 3∶1. Zur Lokalisierung der Flecken wurde die Fluoreszenzlöschung herangezogen. Die Ausbeute nach 30 Minuten Entwicklung auf Silikagelplatten war ungefähr 90% Ametryn, unabhängig vom Laufmittel. Bei zweidimensionaler Arbeitsweise wurden 75% wiedergefunden. Die Ausbeute aus Wasser- und Bodenproben lag zwischen 78 und 88%.
    Notes: Summary The use of the liquid scintillation counting method for the determination of14C labelled ametryne on thin-layer chromatograms has been thoroughly investigated. Aging, quenching effect of carrier and adsorbents as well as temperature stability of the compound in the adsorbed state have been studied. The method has a reproducibility of 1 to 2% and a detection limit of 0.005μg per spot at a 3 ∶ 1 signal to background ratio. Fluorescence quenching was used for the location of spots on the chromatogram. Recovery studies were carried out by this method. After 30 minutes development on a chromatoplate coated with silicagel, about 90% of the ametryne was recovered independent of solvent system used. About 75% of the ametryne was recovered from a two-dimensional chromatogram. Recoveries of ametryne from water and soil samples ranged between 78 and 88%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01216449
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    Paper (German National Licenses)
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