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  • Polymer and Materials Science  (2)
  • 4-Methyl-3-heptanone  (1)
  • 1995-1999  (3)
  • 1915-1919
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Mandibular Gland Secretion in Different Castes of the Leaf-Cutter Ant Atta laevigata (1999)
    Springer
    Journal of chemical ecology 25 (1999), S. 2433-2444 
    Details
    ISSN: 1573-1561
    Keywords: 4-Methyl-3-heptanone ; 4-methyl-3-hexanone ; 4-methyl-3-heptanol ; castes ; Atta laevigata ; Formicidae ; Attini ; leaf-cutting ant ; mandibular gland ; behavior
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Gas chromatography analyses and behavioral assays showed that Atta laevigata, a highly polymorphic ant species, has a mandibular gland secretion that varies with castes. All castes contain 4-methyl-3-heptanone as the main component and its concentration is proportional to head size. Small workers and soldiers, but not medium size workers, also contain 4-methyl-3-heptanol. Queens show variations in their chemical composition after mating, as virgin males contain a secretion dominated by 4-methyl-3-heptanol, and, in a lesser proportion, 4-methyl-3-heptanone. In mated males these proportions are inverted. The compounds 4-methyl-6-hepten-3-one, 4-methyl-4-hepten-3-one, 6-methyl-tetradecene, and 2,6-dimethyl-2-dodecene are found only in queens. The behavioral response elicited by the secretion is mainly alarm, which is elicited more strongly by glands of larger workers. The results suggest that chemical castes, behavioral castes, and morphological castes overlap in this species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1020813905989
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  • 2
    Electronic Resource
    Electronic Resource
    Effect of thermal annealing on the gas permeability of HIQ-40 films (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1741-1745 
    Details
    ISSN: 0887-6266
    Keywords: Liquid crystalline polymer ; permeability ; crystallinity ; annealing ; gases ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The copolyester formed from 40 mol% p-hydroxybenzoic acid (H), 30 mol% isophthalic acid (I), and 30 mol% hydroquinone (Q), designated as HIQ-40, forms isotropic, amorphous films when appropriately cast from a solvent. Thermal annealing leads to a mesogenic texture and some level of crystallinity. It is shown that these ordering processes lead to dramatic reductions in gas permeability; the magnitude of the decrease increases with the size of the penetrant. The current results are consistent with previously reported sorption data for acetone in HIQ-40. © 1996 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Experimental and theoretical estimations of surface tensions for commercial liquid crystalline polymers, Vectra™ A-950, B-950 and Xydar™ SRT-900 (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 1013-1017 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: By using the Lifshitz-Van der Waals-Acid-Base theory, we have determined the surface tensions (γs) of three commercially available liquid crystalline polymers (LCPs) from the measurement of contact angles on thin films. The values obtained are 43.1, 41.1 and 41.5 mJ/m2 (dyn/cm) for Vectra™ A-950, Vectra™ B-950 and Xydar™ SRT-900, respectively. Experimental data suggest that all the three LCPs are monopolar. The strength of Lewis base (tendency to donate a pair of electrons for the formation of a covalent bond) for these three LCPs is as follows: Vectra™ B-950 〉 Xydar™ SRT-900 〉 Vectra™ A-950. We also theoretically estimated γs from both parachor (Ps) and cohesive energy (Ecoh) utilizing the concept of molecular group contribution. It was found that γs's calculated from Hoftyzer & Van Krevelen and Hayes' Ecoh values are close to our experimental results obtained from contact angle measurements. This is especially true for Xydar™ SRT-900 LCP, where γs obtained from contact angle measurements is 41.5 mJ/m2, while from Hoftyzer and Van Krevelen, and Hayes it is 42.4 and 41.8 mJ/m2, respectively. However, more adequate group contributions for naphthalene and amide groups are urgently needed.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
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