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  • 1995-1999  (9)
  • Chemistry  (8)
  • Key words Coloniality  (1)
  • Nuclear reactions
  • 1
    Digitale Medien
    Digitale Medien
    Condition-dependent control of paternity by female purple martins: implications for coloniality (1996)
    Springer
    Behavioral ecology and sociobiology 38 (1996), S. 379-389 
    Details
    ISSN: 1432-0762
    Schlagwort(e): Key words Coloniality ; Purple martin ; Progne subis ; Cuckoldry ; Lek
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract Proposed causal links between extra-pair copulation (EPC) and colony formation in socially monogamous birds hinge on the question of which sex controls fertilizations. We examined in colonial purple martins Progne subis (1) whether EPCs were forced or accepted by females, and (2) the degree to which apparently receptive females were able to obtain EPCs against their mates’ paternity defenses. Paternity analyses of multilocus DNA fingerprinting confirmed previous findings of a marked relationship between age class and extra-pair fertilizations (EPFs), with young males losing paternity of 43% (n = 53) of their putative offspring compared to 4% (n = 85) by old males. All assignable extra-pair offspring were sired by old males, with one male obtaining most EPFs each year. Contrary to the hypothesis that EPCs are forced, EPF frequency within age class did not increase with seasonal increases in the number of males per fertile female. Whereas the male control hypothesis predicted that the male age class that mate-guarded more would be cuckolded less, the reverse was true: young males guarded significantly more intensely. The male age class difference in cuckoldry could not be explained by the possibility that young and inexperienced females (which are usually paired to young males) were more vulnerable to forced copulation because EPFs were unrelated to female age. These findings suggest that females (1) pair with old males and avoid EPCs, or (2) pursue a mixed mating strategy of pairing with young males and accepting EPCs from old males. The receptivity to EPCs by females paired to young males put them in conflict with their mates. Two factors determined the paternity achieved by young males: (1) the relative size of the male to the female, with young males achieving much higher paternity when they were larger than their mates, and (2) the intensity of mate-guarding. Both variables together explained 77% of the variance in paternity and are each aspects of male-female conflict. Given female receptivity to EPCs, mate-guarding can be viewed as male interference with female mating strategies. We conclude that EPCs are rarely or never forced, but the opportunity for females paired to young males to obtain EPCs is relative to the ability of their mates to prevent them from encountering other males. Evidence of mixed mating strategies by females, combined with other features of the martin mating system, is consistent with the female-driven “hidden lek hypothesis” of colony formation which predicts that males are drawn to colonies when females seek extra-pair copulations.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002650050255
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  • 2
    Digitale Medien
    Digitale Medien
    Silicon-Modified Carbohydrate Surfactants I: Synthesis of Siloxanyl Moieties Containing Straight-chained Glycosides and Amides (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 421-435 
    Details
    ISSN: 0268-2605
    Schlagwort(e): siloxanes ; carbohydrate modified ; surfactants ; saccharide ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: New siloxanyl-modified carbohydrate surfactants of the amide and glycoside type have been synthesized by coupling between defined as well as higher-molecular-weight siloxanes and carbohydrate structures via spacers of different lengths and hydrophilic power. Linear and branched monohydrogen di-, tri-, tetra- and penta-siloxanes and polyhydrogen siloxanes as well as mono- and di-saccharide lactone structures have been found to be good starting materials for the synthesis of amides, often in quantitative yield, whereas glycosides had to be prepared in low-yield multistep sequences including protection/deprotection steps. Selected strategies were applied to polysiloxanes yielding quantitatively a broad variety of carbohydrate-modified comb-like structures. The new substances were characterized by means of 13C NMR spectroscopy, GC, capillary GC, GC-MS coupling and elemental analysis.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
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  • 3
    Digitale Medien
    Digitale Medien
    Silicon-Modified Carbohydrate Surfactants II: Siloxanyl Moieties Containing Branched Structures (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 10 (1996), S. 437-450 
    Details
    ISSN: 0268-2605
    Schlagwort(e): siloxanes ; surfactant ; carbohydrate ; amino ; regioselective ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Branched siloxanyl-modified carbohydrate surfactants have been synthesized by coupling mono-, di- and poly-functional siloxanes to carbohydrate units either via a branched spacer or by attaching a separate modifying element to a straight-chained structure. Hydrophilic as well as extremely hydrophobic elements have been incorporated successfully. Siloxanyl-modified carbohydrates bearing a secondary amino function were alkylated in regioselective reactions by different epoxides ranging from glycidol- to siloxanyl-modified allyl glycidyl ether derivatives. Alternatively, carbohydrate-modified piperazinyl structures yielded cyclic subunits after alkylation. Structures bearing two identical hydrophilic groups are accessible by alkylation of carbohydrate-modified bisamides. The derivatives synthesized were characterized by means of GC, NMR and elemental analysis.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Silicon-modified carbohydrate surfactants VI: Synthesis of carbosilane, silane, polysilane and non-permethylated siloxane derivatives; the wetting behaviour of epoxy-modified precursor liquids on non-polar surfacesIn remembrance of Professor Dr Edwin Hengge (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 47-58 
    Details
    ISSN: 0268-2605
    Schlagwort(e): surfactants ; carbohydrate ; carbosilane ; silane ; wetting ; surface tension ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The synthesis of carbohydrate surfactants bearing carbosilane, silane, polysilane and non-permethylated siloxane moieties is described. These surfactants consist of three structural elements: (1) a silicon-containing moiety, (2) a spacer and (3) a carbohydrate unit. Additionally two different types of mixed structures have been synthesized: (a) single-chained carbosilane-siloxane surfactants and (b) double-chained combinations of carbo- silanes, silanes and siloxanes. The wetting behaviour of the key intermediates, the allyl glycidyl derivatives, has been investigated by static surface tension (γlv, σ) and wetting tension (γsv-γsl, α) measurements on a non-polar perfluorinated surface (FEP® plate). The contact angles obtained for these pure liquids are not a linear function of the surface tension but depend on the polarity of the substructures. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 10 Ill.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Silicon-modified carbohydrate surfactants. VII: Impact of different silicon substructures on the wetting behaviour of carbohydrate surfactants on low-energy surfaces  -  distance decay of donor-acceptor forces (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 265-276 
    Details
    ISSN: 0268-2605
    Schlagwort(e): carbohydrate surfactants ; wetting behaviour ; siloxane ; silane ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The wetting behaviour of carbohydrate surfactants bearing siloxane, carbosilane, polysilane or silane moieties has been investigated. By static surface tension (γlv, σ) and wetting tension (γsv-γsl, α) measurements on a non-polar perfluorinated surface (FEP®), the contact angles of aqueous surfactant solutions above the critical micelle formation concentration (cmc) were determined. Surface tension and wetting tension react independently on defined changes in the chemical structure of the surfactant molecules. Siloxane surfactants reduce the surface tension most effectively, whereas for a neopentyl-substituted silane derivative the lowest solid/liquid interfacial tension was found. The data for isomeric siloxanes, carbosilanes and silanes suggest that donor-acceptor forces at solid interfaces have a maximum range of about 4.5 Å. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Silicon-Modified Carbohydrate Surfactants III: Cationic and Anionic Compounds (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 523-538 
    Details
    ISSN: 0268-2605
    Schlagwort(e): silicon-modified ; carbohydrate ; surfactant ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Ionic siloxanyl-modified carbohydrate surfactants have been synthesized by alkylation/esterification of precursors containing tertiary amino functions. Depending on the reaction strategy, the siloxanyl moiety is part of the alkylating agent or the substrate. Polyhydroxylated tertiary amines can be quaternized by siloxanyl-modified chloroacetic acid esters or epoxysiloxanes in the presence of glacial acetic acid. The esterification of tertiary amines bearing carbohydrate and siloxanyl subunits by cyclic acid anhydrides yields, after neutralization, carboxylate salts. The reaction of hydroxyl groups and sulfamic acid leads to sulfates. The new substances were characterized by means of 13C NMR spectroscopy, gas chromatography, elemental analysis and their solubility profile. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 16 Ill.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Silicon-modified carbohydrate surfactants. IV. The impact of substructures on the wetting behaviour of siloxanyl-modified carbohydrate surfactants on low-energy surfaces (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 617-632 
    Details
    ISSN: 0268-2605
    Schlagwort(e): siloxanyl-modified ; carbohydrate ; surfactant ; wetting behaviour ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The siloxanyl-modified carbohydrate surfactants investigated consist of the four structural elements: (1) siloxanyl moiety; (2) spacer; (3) carbohydrate unit; and (4) modifying element. By static surface tension (γsν  -  γsβ α) measurements the contact angles of the aqueous surfactant solutions above the critical micelle formation concentration (cmc) on nonpolar perfluorinated surfaces (FEP® plate) were determined. Although the siloxanyl units were found to have a high capacity to level out the interfacial properties, both surface tension and wetting tension react independently to defined changes in the chemical structure of the surfactant molecules. The results of spreading experiments on polyproylene show good correlation with the dependences found by wetting meaurements. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 17 Ill.
    Materialart: Digitale Medien
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  • 8
    Digitale Medien
    Digitale Medien
    Silicon-Modified Carbohydrate Surfactants V: The Wetting Behaviour of Low-Molecular-Weight Siloxane, Carbosilane, Silane and Polysilane Precursors on Low-Energy Surfaces (1997)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 11 (1997), S. 645-657 
    Details
    ISSN: 0268-2605
    Schlagwort(e): siloxane ; surface tension ; control angle ; interfacial tension ; wetting tension ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The surface tensions, wetting tensions, contact angles and solid/liquid interfacial tensions of defined siloxanes as well as those of analogous carbosilanes, polysilanes and neopentyl substituted silanes were determined. The wetting experiments were carried out on a glass plate coated with perfluoroalkyl methacrylate (FC 722®). The siloxanes possess the lowest surface tensions. Due to the presence of oxygen atoms in the siloxane backbone, a donor-acceptor portion (γ+/-lv) of the surface tension of about 1-2 mN/m was determined. The solid/liquid interfacial tension also contains a donor-acceptor portion (γ+/-sl). Its value is almost identical to that of γ+/-lv. The γ+/-sl differences between individual molecules of the same surface tension are responsible for contact angle differences of up to 4°. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Silicon-modified carbohydrate surfactants IX: dynamic wetting of a perfluorinated solid surface by solutions of a siloxane surfactant above and below the critical micelle concentration (1998)
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 12 (1998), S. 843-853 
    Details
    ISSN: 0268-2605
    Schlagwort(e): carbohydrate-modified phenylsiloxane ; surfactants ; wetting behaviour ; superspreading ; Chemistry ; Industrial Chemistry and Chemical Engineering
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The dynamic wetting behaviour on a perfluorinated, low-energy solid has been investigated for a carbohydrate-modified phenylsiloxane surfactant. The surfactant concentration, the rate of interface generation and the [solid/liquid interface area] : [liquid/vapour interface area] ratio were varied systematically. Dynamic data for the liquid/vapour (γlv) and solid/liquid (γsl) interfacial tension as well as their Lifshitz-van der Waals and donor-acceptor contributions were determined under strictly controlled conditions. Since γsl reacts sensitively to variations of the surfactant concentration and the rate of interface generation, the covering of the liquid/non-polar solid interface is assumed to be a spreading limiting factor. The corresponding γlv values remain constant and close to those obtained under equilibrium conditions. Copyright © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 11 Ill.
    Materialart: Digitale Medien
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