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  • Polymer and Materials Science  (3)
  • Neodiprion autumnalis  (2)
  • 12-methoxyabietic acid  (1)
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Materialart
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  • 1
    Digitale Medien
    Digitale Medien
    Influence of induced water stress in ponderosa pine on pine sawflies (1990)
    Springer
    Oecologia 83 (1990), S. 452-457 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Water stress ; Needle water potentital ; Pinus ponderosa ; Neodiprion fulviceps ; Neodiprion autumnalis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Three levels of water stress were induced on pole-size ponderosa pine (Pinus ponderosa) to determine the influence of plant moisture stress on oviposition, survival, and growth of two species of pine sawfly (Neodiprion fulviceps and N. autumnalis). It was found that water stress affected oviposition and subsequent egg survival but not larval development or survival. Stress had a negative effect on early season oviposition (N. fulviceps) and a positive effect on late season oviposition (N. autumnalis). Egg hatch was different between species and years and among treatment levels. Larval development, feeding, and survival were not affected by water stress. Overall, the effect of stress was not sufficient to explain population outbreaks of sawflies. Several hypotheses are presented as possible explanations for the observed experimental results.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00317194
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  • 2
    Digitale Medien
    Digitale Medien
    Influence of watering and trenching ponderosa pine on a pine sawfly (1987)
    Springer
    Oecologia 71 (1987), S. 382-387 
    Details
    ISSN: 1432-1939
    Schlagwort(e): Host-herbivore interactions ; Water stress ; Herbivory ; Ponderosa pine ; Pinus ponderosa ; Diprionidae ; Sawflies ; Neodiprion autumnalis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Neodiprion autumnalis (Smith) larvae were caged for two successive years on root-trenched, watered, and untreated ponderosa pine (Pinus ponderosa Doug. ex Laws.) to determine effects of host moisture stress on larval feeding. Levels of moisture stress (as measured by the Scholander pressure chamber) differed significantly among treatment levels during 1984 and 1985 larval feeding periods. Differences in larval feeding success were not detected in 1984. In 1985, however, larvae on trenched (stressed) trees clipped and rejected more foliage, consumed more needles, had lower pupal weights, lower survival, and a longer feeding period than larvae on watered or untreated trees. Frass production did not differ among treatment levels. The length of the feeding period was shorter for larvae on watered trees than for larvae on untreated trees, but other measures of feeding success did not significantly differ between watered and untreated trees.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00378711
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  • 3
    Digitale Medien
    Digitale Medien
    Chemical basis of differential feeding behavior of the larch sawfly,Pristiphora erichsonii (Hartig) (1981)
    Springer
    Journal of chemical ecology 7 (1981), S. 599-614 
    Details
    ISSN: 1573-1561
    Schlagwort(e): Larch ; tamarack ; larch sawfly ; Pristiphora erichsonii ; abietic acid ; dehydroabietic acid ; 12-methoxyabietic acid ; sandaracopimaric acid ; isopimaric acid ; Larix laricina
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Abstract The machanisms by which the larvae of the larch sawfly,Pristiphora erichsonii (Hartig), are prevented from feeding on the single needles of the new shoot of tamarack,Larix laricina (DuRoi) K. Koch, were studied. As a result of extensive purification attempts, five deterrent chemicals were isolated and identified. They are: abietic, dehydroabietic, 12-methoxyabietic, sandaracopimaric, and isopimaric acid. These chemicals, particularly the first two, are abundant in mid-July to August in the single needles and, apparently, provide the basis for the deterrency against the larval feeding.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00987708
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  • 4
    Digitale Medien
    Digitale Medien
    Network disentanglement and time-dependent flow behaviour of polymer meltsHerrn Prof. Dr. H. Batzer zum 60. Geburtstag gewidmet (1980)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 1533-1550 
    Details
    ISSN: 0025-116X
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: For small strains Lodge's rubberlike-liquid theory is a valid description of the rheological behaviour of polymer melts, but at higher strains the theory fails: The phenomenon of shear thinning which is characteristic for the shear flow of nearly all polymer liquids is not explained, and in elongation the deviation of the experimental data from the predictions of Lodge's theory reflect also a flow thinning, and not a strain hardening in spite of the pronounced S-shape of the stress-strain diagrams. Comparing the measured stress growth and stress relaxation data with the predictions of the theory, it must be concluded that the temporary physical network structure of the polymer melt is destroyed increasingly with the magnitude of the deformation. Hence, the number of entanglements decreases with increasing strain. For simple shear and uniaxial extension of a well-defined polyethylene melt the strain dependence of the relative entanglement density is discussed. The irreversibility of the disentanglement process of the network is considered.
    Zusätzliches Material: 14 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/macp.1980.021810716
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  • 5
    Digitale Medien
    Digitale Medien
    Stress Hypotheses and material stresses in Hertzian contacts (1986)
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 17 (1986), S. 238-246 
    Details
    ISSN: 0933-5137
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Beschreibung / Inhaltsverzeichnis: Spannungshypothesen und Werkstoffanstrengung im Hertz'schen KontaktDer Spannungszustand im Halbraum des Hertz'schen Kontaktbereichs kann unter idealisierten Annahmen für verschiedene Geometrien in Abhängigkeit von der Flächenpressung (Normalkraft), der Reibung (Tangentialkraft an der Oberfläche) sowie den Eigenspannungen im Werkstoff berechnet werden.Aus den Koordinatenspannungen lassen sich Vergleichsspannungen nach verschiedenen Anstrengungshypothesen (Gestaltänderungsenergiehypothese, Schubspannungshypothese und Wechselschubspannungshypothese) bilden.Untersucht wird die Wirkung von Reibung, Eigenspannungen und Geometrie der Kontaktfläche auf die Vergleichsspannung nach den einzelnen Anstrengungshypothesen. Es erfolgt die Darstellung des Einflusses dieser Parameter auf Ort und Betrag des im Werkstoff auftretenden Vergleichsspannungsmaximums.Anhand dieser Untersuchungen wird deutlich, daß die Gestaltänderungsenergiehypothese bei dynamisch beanspruchten Wälzelementen die Werkstoffanstrengung am besten beschreibt. Die Schubspannungshypothese kann als gute Näherung aufgefaßt werden, während die Wechselschubspannungshypothese nur sehr eingeschränkt aussagefähig ist.
    Notizen: Using idealised assumptions, the stress condition in the semi infinite body of the Hertzian contact region can be calculated for various geometries as a function of the surface pressure (normal force), the friction (tangential force at the surface) and the residual stresses in the material.Equivalent stresses can be formed from the coordinate stresses using various stress hypotheses (distortion energy hypothesis, shear stress hypothesis and alternating shear stress hypothesis).The effects of friction, residual stresses and contact geometry on the location and magnitude of the equivalent stresses appearing in the material have been investigated, the stress hypotheses being evaluated in terms of the extent to which they take account of these effects in an appropriate form.These investigations show clearly that the distortion energy hypothesis is the best representation of the extent of material stress in the case of dynamically loaded rolling elements. The shear stress hypothesis can be considered as a good approximation whereas the alternating shear stress hypothesis is only capable of providing useful conclusions to a limited extent.
    Zusätzliches Material: 12 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mawe.19860170706
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  • 6
    Digitale Medien
    Digitale Medien
    Peroxide- and radiation-cured compounds filled with reinforcing fine-particle silicaPresented before the Division of Rubber Chemistry at the 138th meeting of the American Chemical Society, New York, September 1960. (1961)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 5 (1961), S. 397-400 
    Details
    ISSN: 0021-8995
    Schlagwort(e): Chemistry ; Polymer and Materials Science
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Maschinenbau , Physik
    Notizen: There are indications that the chemical reaction involved in bound rubber formation proceeds via a free-radical mechanism for compounds filled with reinforcing hydrated fine-particle silica, as well as in the case of carbon black as filler. The high potential of silica as a rubber reinforcer is indicated by its bound rubber formation. This potential was realized by the extent of filler-polymer interaction developed in silica-filled vulcanizates cured by peroxide and by high-energy radiation, respectively. Both these relatively simple curing systems are postulated to effect crosslink formation via a free-radical mechanism. The value, after cure, of the ratio of the crosslink density of the filled compound to the crosslink density of the respective unfilled compound, η/η0, was taken to be a logical measure of the ability to reinforce. In natural rubber compounds filled with silica (30 vol.), the values of η/η0 obtained were 1.6-1.9 for peroxide-cured material, and 3.6 for radiation-cured material. Comparisons are made with similarly cured HAF black-filled stocks. Sulfur-cured natural rubber stocks filled with HAF black (30 vol.) generally exhibit η/η0 values in the range of 1.5 to 2.0. Comparative effects of antioxidants are described.
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/app.1961.070051604
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