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  • ASTRODYNAMICS  (8)
  • Polymer and Materials Science  (6)
  • Atomic and molecular collisions and interactions  (3)
  • Helicoverpa zea  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 20 (1994), S. 639-650 
    ISSN: 1573-1561
    Keywords: Soybean ; lipoxygenase ; peroxidase ; polyphenol oxidase ; trypsin inhibitor ; ascorbate oxidase ; oxidative stress ; Lepidoptera ; Noctuidae ; Helicoverpa zea ; corn earworm ; Cerotoma trifurcata ; bean leaf beetle ; Coleoptera ; Chrysomelidae ; Spissistilus festinus ; three-cornered alfalfa hopper ; Homoptera ; Membracidae ; induced resistance ; interspecific competition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Variation in induced responses in soybean is shown to be dependent, in part, upon herbivore species. Herbivory by the phloem-feeding three-cornered alfalfa hopper caused increases in the activities of several oxidative enzymes including lipoxygenases, peroxidases, ascorbate oxidase, and polyphenol oxidase. Bean leaf beetle defoliation caused increased lipoxygenase activity, but had little effect upon peroxidase, polyphenol oxidase, ascorbate oxidase, or trypsin inhibitor levels in either field or greenhouse studies. In one field experiment, prior herbivory by the bean leaf beetle subsequently reduced the suitability of foliage to the corn earwormHelicoverpa zea. The contribution of these findings to emerging theories of insect-plant interactions is discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 20 (1994), S. 183-198 
    ISSN: 1573-1561
    Keywords: Induced resistance ; protein quality ; Helicoverpa zea ; soybean ; Glycine max ; protease inhibitor ; lipoxygenase ; Lepidoptera ; noctuidae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Resistance in soybean toHelicoverpa zea is comprised of both constitutive and inducible factors. In this study, we investigated the induction of resistance byH. zea in both greenhouse and field studies. In a greenhouse experiment, fourth-instarH. zea growth rates were reduced by 39% after 24 hr feeding and by 27% after 48 hr when larvae fed on previously wounded V3 foliage (cv. Forrest) compared with undamaged foliage. In a field study, the weight gain by larvae was more than 52% greater when larvae fed for 72 hr on undamaged R2/R3 soybean plants (cv. Braxton) compared to those that fed on previously wounded plants. A significant component of the induced resistance is due to a decline in the nutritional quality of foliar protein following foliar damage byH. zea. Foliar protein was extracted from damaged and undamaged foliage and incorporated into artificial diets. Larval growth was reduced 26% after four days and 49% after seven days on diets containing protein from damaged plants compared to larvae feeding on foliar protein from undamaged plants. Chemical analyses of protein quality also indicated a decline in quality in damaged plants compared to unwounded plants. Increases in lipoxygenase activity (53%), lipid peroxidation products (20%), and trypsin inhibitor content (34%) were observed in protein from wounded plants. Moreover, a 5.9% loss in free amines and 19% loss in total thiols occurred in protein from wounded plants. Larval feeding causes a significant increase in foliar lipoxygenase activity that varied among genotypes. Lipoxygenase isozymes were measured at pH 5.5, pH 7.0, and pH 8.5 in V3 stage plants of Forrest, Hark, D75-1069, and PI 417061 genotypes. Lipoxygenase activity in each genotype was significantly increased after 72 hr of larval feeding at each pH level tested, with the exception of lipoxygenase isozymes at pH 5.5 in genotype PI 417061. Larval feeding on R2/R3 stage plants (field-grown cv. Braxton) for six days also increased foliar lipoxygenase activity.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 497-505 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Unter der Voraussetzung, daß der Abbruch bei der anionischen Polymerisation von Methylmethacrylat in Tetrahydrofuran mit Cumylcäsium als Initiator ausschließlich durch das Monomere verursacht wird, wird die Abbruchsgeschwindigkeitskonstante kt± für die Ionenpaare des Polymethylmethacrylcäsiums aus der Molekulargewichtsverteilung von Polymeren, die bei verschiedenen Temperaturen unter sonst gleichen Bedingungen hergestellt wurden, abgeschätzt. Die Abbruchreaktion hat eine Aktivierungsenergie von etwa 11 kcal/mol (46 kJ/mol). - Die relativ große Breite der Verteilung der nicht desaktivierten Ketten („interne Uneinheitlichkeit“) zeigt deutlich die Existenz von verschieden reaktiven Ionenpaararten.
    Notes: Based on the assumption that the termination reaction in the anionic polymerization of methyl methacrylate in THF with cumyl cesium as initiator is exclusively caused by the monomer, the termination rate constant kt(±) for the ion-pairs of polymethylmethacrylcesium is estimated by analyzing the molecular weight distribution (MWD) of polymer samples prepared at different temperatures under otherwise identical reaction conditions. The activation energy of the termination reaction of the ion-pairs is found to be about 11 kcal/mol (46 kJ/mol). - The relatively broad MWD of the non-deactivated chains (the so called internal nonuniformity) reveals the existence of ion-pairs with different reactivity.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 20 (1994), S. 651-666 
    ISSN: 1573-1561
    Keywords: Helicoverpa zea ; Lepidoptera ; Noctuidae ; lipoxygenase ; lipid peroxidation ; resistance ; herbivory ; soybean ; tomato ; cotton ; oxidative stress ; induced defense
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The potential role of the plant enzyme lipoxygenase in host resistance against the corn earwormHelicoverpa zea was examined. Lipoxygenase is present in most of the common host plants ofH. zea, with highest activity in the leguminous hosts such as soybean and redbean. Treatment of dietary proteins with linoleic acid and lipoxygenase significantly reduced the nutritive quality of soybean protein and soy foliar protein. Larval growth was reduced from 24 to 63% depending upon treatment. Feeding byH. zea on soybean plants caused damage-induced increases in foliar lipoxygenase and lipid peroxidation products. Larvae feeding on previously wounded plant tissue demonstrated decreased growth rates compared to larvae feeding on unwounded tissue. Midgut epithelium from larvae feeding on wounded tissues showed evidence of oxidative damage as indicated by significant increases in lipid peroxidation products and losses in free primary amines. The potential role of oxidative and nutritional stress as a plant defensive response to herbivory is discussed.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Materialwissenschaft und Werkstofftechnik 26 (1995), S. 442-449 
    ISSN: 0933-5137
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Method for a Strength Evaluation of Multiaxial Stochastic Loaded Nodular and Malleable IronThere will be presented a method for an analytic strength evaluation of multiaxial stochastic loaded components (method of reference stress).For the failure of the investigated casted material, breaking up events which are caused by a nominal stress in the maximal stressed sectional plane are responsible and which can be described by a ‚reference stress“. This „Reference stress“, which in its meaning corresponds to an equivalent stress, can be understood not only as a value related to material behaviour, but takes also into account statistical aspects basing on the independence of random values. For a strength evaluation they are compared with the corresponding uniaxial nominal stress.The methodology was verified by multiaxial fatigue tests under combined tensional and torsional loading.
    Notes: Es wird eine Methode zur rechnerischen Festigkeitsbeurteilung mehrachsig unkorreliert stochastisch beanspruchter Konstruktionen vorgestellt (Referenzspannungsmethode).Für das Versagen der untersuchten Gußwerkstoffe sind Trennvorgänge durch eine Normalspannung in der maximal beanspruchten Schnittebene maßgebend, die mittels einer „Referenzspannung“ beschrieben werden kann. Die „Referenzspannung“, die in ihrer Bedeutung einer Vergleichsspannung entspricht, versteht sich nicht nur als rein werkstoffmechanische Größe, sondern berücksichtigt darüberhinaus auch statistische Gesichtspunkte auf Basis der Unabhängigkeit von Zufallsgrößen. Für eine Festigkeitsbeurteilung wird sie mit einer entsprechenden einachsigen Normalspannung verglichen.Das Verfahren wurde durch mehrachsige Versuche unter kombinierter Zug-Druck- und Torsionsbelastung verifiziert.
    Additional Material: 11 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 2863-2879 
    ISSN: 0887-6266
    Keywords: semicrystalline polymers ; polycarbonate ; TSDC ; rigid amorphous phase ; glass transition ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Thermally Stimulated Depolarization Current technique, Differential Scanning Calorimetry, and Dynamic Mechanical Analysis have been applied to amorphous and semicrystalline bisphenol-A polycarbonate with crystallinity degrees up to 21.8%, in a temperature interval covering the α and β relaxations. The secondary β transition is found to be the sum of three components whose variations in aged and annealed specimens have shown the cooperative character of the β1 and β2 modes, contrary to the localized nature of the β3 component. A Tg decrease was observed by both TSDC and DSC as a function of Xc and has been related to the possible confinement of the mobile amorphous phase in regions whose sizes are smaller than the correlation lengths of the cooperative movements that characterize the motions occurring at Tg. The α relaxation intensity variations with crystallinity show the existence of an abundant rigid amorphous phase in the semicrystalline material. The relaxation parameters deduced from the Direct Signal Analysis of the α relaxation for the mobile amorphous phase do not show significant deviations from those found for the amorphous material. The existence of the rigid amorphous phase has been associated to the ductile-to-brittle transition experienced by the material at low crystallinity levels. © 1996 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
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  • 7
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The hydrogenation of polystyrene-block-polybutadiene-block-poly(ε-caprolactone) SBC triblock copolymers was performed in the presence of the Wilkinson catalyst RhCl(P(C6H5)3)3. Reaction conditions (hydrogen pressure, temperature and reaction time) were varied to ensure quantitative hydrogenation without detectable side reactions. Gel permeation chromatography showed no broadening of the molecular weight distribution during hydrogenation. The efficiency of the catalyst is markedly influenced by the molecular weight of the copolymer. Due to the presence of the polyethylene (PE) block, the resulting polymers exhibit a reduced solubility in comparison to the starting materials. Using differential scanning calorimetry (DSC), preliminary results about the crystallization and melting behavior of the PE-block were obtained. In the triblock copolymers, the PE-block showed a marked depression of the melting point and crystallinity when compared to pure hydrogenated polybutadiene of equivalent molecular weight and microstructure or to a comparable PE-block within a polyethylene-block-poly(ε-caprolactone) diblock copolymer. A fractionated crystallization process of the PCL-block was observed when the PCL component in the hydrogenated triblock copolymers was present as a minor phase.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Chemie Ingenieur Technik - CIT 63 (1991), S. 733-735 
    ISSN: 0009-286X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 2 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 1 (1980), S. 363-368 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
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  • 10
    Publication Date: 2011-03-31
    Description: Author(s): C. Makochekanwa, J. R. Machacek, A. C. L. Jones, P. Caradonna, D. S. Slaughter, R. P. McEachran, J. P. Sullivan, S. J. Buckman, S. Bellm, B. Lohmann, D. V. Fursa, I. Bray, D.W. Mueller, A. D. Stauffer, and M. Hoshino Cross sections for positron scattering from krypton have been measured with an energy resolution of ∼60 meV over the energy range 0.5–60 eV. Absolute values of the grand total (σ_{GT} ), positronium formation (σ_{Ps} ), and grand total minus positronium formation (σ_{GT} -σ_{Ps} ,) cross se... [Phys. Rev. A 83, 032721] Published Wed Mar 30, 2011
    Keywords: Atomic and molecular collisions and interactions
    Print ISSN: 1050-2947
    Electronic ISSN: 1094-1622
    Topics: Physics
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