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  • 1
    Electronic Resource
    Electronic Resource
    Darwin's Ambiguity: The Secularization of Biological Meaning (1989)
    Cambridge : Cambridge University Press
    The @British journal for the history of science 22 (1989), S. 215-239 
    Details
    ISSN: 0007-0874
    Source: Cambridge Journals Digital Archives
    Topics: History , Natural Sciences in General
    Notes: Darwin is well known for his wondrously ambiguous rhetoric. The author who used an ‘entangled bank’ as his metaphor for Nature and its complex relationships built up the substance of his text from a corresponding entanglement of unresolved theoretical relations. Ambiguous positions, arguments that seem to fold in on themselves, vacillations, contradictions, and pluralities of explanation suffuse Darwin's science and its constituent metascience. The Origin abounds in ambiguities with regard to the technical features of evolutionary biology. But the domain of ambiguity I wish to address is Darwin's metaphysical stance. I want to approach the question of Darwin and secularization through what might be called the trope of ambiguity. My principle concern is with the origins of that ambiguity. These lie in the conflicting cultural and ideological resources Darwin used to construct the theory of natural selection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1017/S0007087400026005
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  • 2
    Electronic Resource
    Electronic Resource
    What Henslow taught Darwin (2005)
    [s.l.] : Nature Publishing Group
    Nature 436 (2005), S. 643-645 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The kindly Professor John S. Henslow of Cambridge, well known for arranging Charles Darwin's berth on HMSBeagle, was also a rigorous researcher who recorded patterns of variation within and between plant populations and was motivated to understand the nature of species: the big question of natural ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/436643a
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  • 3
    Electronic Resource
    Electronic Resource
    Enzymatic polyesterification in organic media. Enzyme-catalyzed synthesis of linear polyesters. I. Condensation polymerization of linear hydroxyesters. II. Ring-opening polymerization of ∊-caprolactoneThis article is taken in part from a dissertation submitted by Dafna Knani to the Department of Chemistry, Technion-Israel Institute of Technology, Haifa, in October 1990, in partial fulfillment of the degree of D.Sc.The paper is dedicated to the memory of Prof. D. H. Kohn who died before it was completed. (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 1221-1232 
    Details
    ISSN: 0887-624X
    Keywords: enzymatic polymerization ; organic solvents ; polyesters ; macrolactones ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: With the object to synthesize polyesters by enzymatic catalysis in organic media, two directions have been investigated: (1) the condensation polymerization of linear ω-hydroxyesters and (2) the ring-opening polymerization of lactones. The commercially-available crude porcine pancreatic lipase (PPL), suspended in organic solvents, was the preferred enzyme for the reactions. In order to determine the optimal conditions for the condensation polymerization, the bifunctional methyl 6-hydroxyhexanoate was used as a model compound to study the influence of the following parameters: type of the enzymecatalyst, kind of solvent, concentration, temperature, duration, size of the reaction mixture, and stirring. Film-forming polyesters with a degree of polymerization (DP) up to about 100 were obtained from linear aliphatic hydroxyesters in n-hexane at reflux temperature (69°C). Yet concurrently with the intermolecular condensation polymerization, macrolactones were also formed by intramolecular reaction. Two aromatic hydroxyesters did not react under these conditions. For the ring-opening polymerization of lactones the reaction of ∊-caprolactone with methanol as the preferred nucleophile, was studied. Polyesters with a DP of up to 35 were obtained in n-hexane at temperatures between 25 and 40°C. The degrees of polymerization of the polyesters were determined by comparative analyses of the end groups in the 1H-NMR spectra and by determination of molecular weights either by vapor phase osmometry, gel permeation chromatography, or intrinsic viscosity. © 1993 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310518
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  • 4
    Electronic Resource
    Electronic Resource
    Enzymatic polyesterification in organic media. II. Enzyme-catalyzed synthesis of lateral-substituted aliphatic polyesters and copolyestersThis article was taken in part from a dissertation submitted by Dafna Knani to the Department of Chemistry, Technion-Israel Institute of Technology, Haifa, Israel, in October 1990, in partial fulfillment of the degree of D.Sc. (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 2887-2897 
    Details
    ISSN: 0887-624X
    Keywords: enzymatic polymerization ; enzymatic copolymerization ; chiral hydroxyesters ; organic solvents ; optically active polyesters ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Enzymatic polymerization of hydroxyesters in organic media has been the subject of a previous and ongoing research in our laboratory. As part of that study, four ∊-substituted-∊-hydroxyesters were synthesized, and then polymerized using crude porcine pancreatic lipase (PPL) in n-hexane. These lateral-substituted hydroxyesters polymerized enantioselectively to produce optically active oligomers and a resolved optically active unreacted monomer. It was found that with increasing bulkiness of the lateral substituent, in the order Me 〉Et 〉Ph, the enzymatic reaction becomes slower, yet the enantioselectivity is higher. The lateral-substituted hydroxyesters were also copolymerized enzymatically with the more reactive linear methyl ∊-hydroxyhexanoate. Optically active copolymers were obtained, higher in molecular weight than the analogous homopolymers. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080311202
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  • 5
    Electronic Resource
    Electronic Resource
    Copolymerization of styrene. IV. Copolymerization with esters of benzylidenecyanoacetic acid (1970)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 14 (1970), S. 1491-1505 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Styrene was copolymerized in bulk with a number of esters of benzylidenecyanoacetic acid. The kinetic scheme of all pairs fitted the improved scheme of copolymerization, taking into account the effect of the penultimate unit. The Alfrey-Price Q and e values were calculated. Using the modified Taft equation, log (1/r1) = ρ*σ* + δEs, it was found that the relative reactivities of the ester monomers toward the polystyryl radical were correlated by the polar substituent constants σ* of the ester alkyl groups (ρ* = 0.14) and not by their steric substituent constants Es (δ = 0.008).
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1970.070140607
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  • 6
    Electronic Resource
    Electronic Resource
    Copolymerization of styrene with vinyl monomers substituted by nitrile and sulfonyl groups (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1941-1952 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Two trisubstituted vinyl monomers, 2-phenylsulfonyl (crotonitrile) and 2-phenylsulfonyl (cinnamonitrile) were synthesized and characterized by proton NMR, IR, 13C-NMR, and mass spectroscopy. Both monomers were copolymerized with styrene by free-radical initiation. The copolymerization parameters of both systems were determined, and the mutual reactivity of the monomers of the two systems is discussed. The new copolymers were characterized by proton NMR and IR spectroscopy, melting range, Tg, and intrinsic viscosity. The influence of the chemical structures of the two comonomers on these two latter properties of the copolymers is discussed.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070431019
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  • 7
    Electronic Resource
    Electronic Resource
    Polymerization of acrylamide in the presence of calcium sulfate dihydrate and calcium sulfate hemihydrate (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 45 (1992), S. 2079-2089 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The homopolymerization of acrylamide in water alone and also in the presence of calcium sulfate dihydrate and of calcium sulfate hemihydrate has been studied. Polymerizing acrylamide with the redox pair potassium persulfate - sodium bisulfite, the rate increased steadily with increasing initiator concentration. In the presence of up to 25% dihydrate, the rate was like that of acrylamide alone. However, when adding the “reactive” hemihydrate that is hydrated to the dihydrate concurrently with the progressing polymerization, the rate is somewhat slower in comparison with the two other systems. For determination of the compositions of the various reaction products, a method combining DTA and XRD data has been developed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070451203
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  • 8
    Electronic Resource
    Electronic Resource
    Terpolymerization studies: IV. Terpolymerization of ethyl acrylate, ethyl α-cyanocinnamate, and styrene (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1121-1124 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Ethyl acrylate, ethyl α-cyanocinnamate, and styrene were terpolymerized by free radical initiation at 60°C up to low conversion. The relationships between monomer feed and compositions of the terpolymers were determined by a triangular graph according to Slocombe. The terpolymers were characterized by their IR and Proton NMR spectra, intrinsic viscosity, and thermal behaviour. For a selected terpolymer, its adhesive properties for a number of substrates was investigated.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420425
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  • 9
    Electronic Resource
    Electronic Resource
    Polymers with pendant isocyanate groups. II. Dual synthesis and properties of poly(acrylonitrile-co-styryl isocyanate) (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 1795-1802 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The copolymer poly(acrylonitrile-co-styryl isocyanate) was prepared directly in bulk by radical initiation either from the monomer pair acrylonitrile-cinnamoyl azide or from the pair acrylonitrile-styryl isocyanate. The copolymerization parameters, calculated by the conventional scheme, are r1, = 3.5 ± 0.5; r2 = 0 ± 0.5, for the first pair and r1 = 9 ± 0.5; r2 = 0 ± 0.5 for the second pair. The basic physical properties (solubility, intrinsic viscosity, and thermal behavior) of the new copolymer were determined and the chemical reactions of the isocyanate group with alcohol and with dimethylformamide were investigated.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1976.070200709
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  • 10
    Electronic Resource
    Electronic Resource
    Polymers with pendant isocyanate groups. I. Dual synthesis and properties of poly(styrene-co-styryl isocyanate) (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 411-420 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The copolymer poly(styrene-co-styryl isocyanate) was synthesized directly by radical initiation from two different monomer pairs: styrene-cinnamoyl azide and styrene-styryl isocyanate. The copolymerization parameters r1 = 0.93 ± 0.08, r2 = -0.7 ± 0.8 for the first monomer pair and r1 = 7.8 ± 0.6, r2 = 0 ± 0.3 for the second pair were determined according to the conventional scheme of copolymerization. The intrinsic viscosities and the thermal behavior of the various copolymers were determined. Further, the chemical reactivity of the pendant isocyanate groups toward alcohol and amines was investigated.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1976.070200214
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