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  • 1
    Electronic Resource
    Electronic Resource
    Mercaptan derivatives as modifiers in the copolymerization of butadiene and styreneThis investigation was carried out under the sponsorship of the Office of Rubber Reserve, Reconstruction Finance Corporation, in connection with the Government Synthetic Rubber Program. (1948)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 3 (1948), S. 50-57 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: It has been demonstrated that the homogeneity in respect to molecular weight of emulsion copolymers of butadiene and styrene can be increased by the use of certain derivatives of n-dodecyl mercaptan rather than the mercaptan itself. These derivatives decompose and relase n-dodecyl mercaptan at an even rate during the polymerization reaction. Several new derivatives of n-dodecyl mercaptan are described.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1948.120030107
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  • 2
    Electronic Resource
    Electronic Resource
    The conversion of two-stranded poly (A + U) to, three-strand poly (A + 2U) and poly A by heatA Preliminary report of this work was presented before the Biophysical Society at its Eighth Annual Meeting, Chicago, Illinois, February, 1964. (1964)
    New York : Wiley-Blackwell
    Biopolymers 2 (1964), S. 293-314 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown that the formation of the three-strand poly (A + 2U) complex is accompanied by a decrease in optical absorbance at 280 mμ, while the format ion of poly (A + U) is not. This difference makes it possible to demonstrate that in dilute solutions (∼10-4 monomolar), a 1 : 1 mixture of poly A and poly U always forms poly (A + U) at room temperature. At higher temperatures in solutions containing more than about 0.2M sodium ion, poly (A + U) is converted to poly (A + 2U) and free poly A. These results are consistent with the observations reported by Miles and Frazier, using infrared absorption spectra, at much higher polymer concentrations. It is concluded that most of the physicochemical studies of 1 : 1 mixtures of poly A and poly U in dilute aqueous solution refer to the two-stranded species.A simple thermodynamic analysis is developed to explain the two- to three-strand conversion, and with the use of a “phase diagram” showing conditions of stability of the various poly A-poly U structures as a function of salt and temperature, it is possible to estimate the value of the enthalpy of formation of poly (A + 2U).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1964.360020402
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  • 3
    Electronic Resource
    Electronic Resource
    Optical activity of saccharides - the vacuum-uv origin of sodium-D rotation (1988)
    New York : Wiley-Blackwell
    Biopolymers 27 (1988), S. 415-421 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A semiempirical theory of saccharide optical activity indicates that the dominant source of NaD rotation is a vacuum-uv CD band near 150 nm, a band observed experimentally in polysaccharide film CD spectra. The model is a modification of polarizability theory in which high-energy electronic excitations are coupled by degenerate perturbation theory, giving rise to “molecular excitons.” The existence of an excitation mode well separated in energy from even higher energy modes arises from the local symmetry of tetrahedral carbon atoms in a puckered ring structure. Calculated NaD rotations correlate well with experimental values.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360270305
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  • 4
    Electronic Resource
    Electronic Resource
    A reexamination of the double-helix model for agarose gels using optical rotation (1995)
    New York : Wiley-Blackwell
    Biopolymers 36 (1995), S. 103-108 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The diffuse x-ray diffraction patterns of agarose gels are compatible with both the “chicken-wire” gel model consisting of associated double-helix chain conformations and a network of more extended, but unentwined helices. Preference f or the double-helix model has largely rested on an early interpretation of optical rotation data. Applying a recent, less empirical, chiroptical model of saccharide rotation, we confirm the earlier analysis by concluding that the rotation observed in the gel can be satisfactorily accounted for in terms of wide-diameter agarose helices, capable of intertwining. In addition, we have found that the extended helices found in dried sols do not yield the observed gel rotations. © 1995 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360360109
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  • 5
    Electronic Resource
    Electronic Resource
    Vacuum-ultraviolet circular dichroism of chondroitins and their complexes with poly(L-arginine) (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1565-1573 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The vacuum-ultraviolet circular dichroism (VUCD) of chondroitin and chontroitin-6-sulfate has been measured to 160 nm for films and to 170 nm for D2O solutions. The pD-dependent dichroic behavior of these glycosaminoglycans in D2O is similar above 200 nm and is in agreement with previous studies. Near 190 nm, the CD band sign is also dependent on pD. VUCD spectra were recorded for films and solutions of poly(L-arginine). In trifluoroethanol the polypeptide is α-helical, while in D2O it exists as a random coil. The well-characterized coil-helix transition of poly(L-arginine) during complexation with chondroitin-6-sulfate was observed by VUCD, including the previously inaccessible entire π → π* band. By construction of difference spectra it was also possible to monitor the VUCD of the polysaccharide component during complexation.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200713
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  • 6
    Electronic Resource
    Electronic Resource
    Random-phase calculation of the low-energy circular dichroism in glucans (1985)
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 1365-1383 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The CD of the long-wavelength electronic transition in the α-(1 → 4)-linked glucan dimer (maltose) and polymer (amylose), and in the β-(1 → 6)-linked dimer (gentiobiose) and polymer (pustulan), are calculated in the random-phase approximation using time-dependent Hartree theory. This long-wavelength transition (180-190 nm) is assumed to be localized on the linkage oxygen atom and to be of a σ*/3 s ← n character. The zerothorder σ*/3s ← n magnetic-dipole transition moment is coupled to the CC, CO, and CH bond density of states via a polarizability approximation. We assume this coupling is dominated energetically by the electric-dipole, electric-dipole interaction terms in the context of Schellman's μe-μm coupling mechanism of rotatory power. The CD is calculated as a function of rotation about the two single bonds of the linkage oxygen atom and also as a function of rotation about the C(5)-C(6) bond. For maltose, four rotational isomers are considered, resulting from combinations of the gg and gt C(6)H2OH group rotational isomers. The calculated CD values were then Boltzmann-averaged over an empirical potential, and the resulting CD was found to compare satisfactorily with experiment. In the case of the polymers, only structures having periodicity (helicity) were examined.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360240719
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  • 7
    Electronic Resource
    Electronic Resource
    Total optical activity of agarose: Relation to observable transitions in the vacuum ultraviolet (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 959-973 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The changes in optical activity that accompany and characterize the coil-helix and helix-coil transitions of agarose in aqueous solutions and gels have been investigated by combined quantitative analysis of data from vacuum ultraviolet circular dichroism (VUCD) and optical rotary dispersion (ORD). VUCD of agarose in the high-temperature coil state shows a single accessible Gaussian band centered at ∼183 nm. In the helix state this band is blue-shifted by ∼9 nm, and the intensity is increased by a factor of ∼2.6. Spectra at intermediate temperatures can be fitted to within experimental error by linear combination of coil and helix spectra, the relative proportions required providing an index of the extent of conformational ordering. ORD spectra throughout the conformational transition have a common form and differ only in absolute magnitude. The temperature course of conformational ordering derived from ORD intensity is in close agreement with the values obtained from VUCD. In both the coil and helix states the accessible VUCD band is positive, while the overall ORD is negative, indicating strong negative CD activity at lower wavelength. The ORD contribution corresponding to the positive VUCD band was calculated by Kronig-Kramers transform, and it was subtracted from the total ORD to give the residual ORD from all other optically active transitions of the molecule. In both the coil and helix states, this residual ORD could be fitted to within experimental error by a single Gaussian CD band at ∼149 nm. A negative band at this wavelength has been reported previously for agarose films, but the observed intensity, relative to that of the lower energy positive band, is substantially smaller than the fitted value under hydrated conditions. In both the coil and helix states the total optical activity of agarose, characterized by observed ORD spectra, can be matched to within experimental error by Kronig-Kramers transform of the 149-nm negative band and the smaller positive band at higher wavelength, with no necessary involvement of deeper-lying transitions. The significance of this conclusion for fundamental understanding of carbohydrate optical activity is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360250514
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  • 8
    Electronic Resource
    Electronic Resource
    The potential energy surface of methyl 3-O-(α-D-mannopyranosyl)-α-D-mannopyranoside in aqueous solution: Conclusions derived from optical rotation (1994)
    New York : Wiley-Blackwell
    Biopolymers 34 (1994), S. 1395-1401 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical rotation of methyl 3-O -(α-D-mannopyranosyl)-α-D-mannopyranoside is calculated semiempirically as a function of the linkage dihedral angles φ (H1-C1-O1-C3′) and ψ (C1-O1-C3′-H3′). Comparison with the observed optical rotation in aqueous solution indicates the existence of at least two conformers in solution, which implies a degree of linkage flexibility. The result is in agreement with some, but not all, calculated potential energy surfaces, and with recently published nmr data. © 1994 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360341010
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  • 9
    Electronic Resource
    Electronic Resource
    Mechanism of ε-Caprolactone polymerization by Aluminum AlkoxidesHeartily dedicated to Professor Herman Mark for his 80th birthday, in homage to his tireless devotion to the progress of polymer science (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 191-201 
    Details
    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: Es wird gezeigt, daß sich reines Aluminiumisopropoxid als ein hochaktiver Katalysator bei der Polymerisation von ε-Caprolacton bewährt: die Gesamtkinetik dieser Polymerisation ist erster Ordnung für das Monomer und erster Ordnung für den Katalysator.Eine mechanistische Untersuchung zeigt auch, daß dieses System eine selektive Acyl-Sauerstoff-Spaltung des Lactonringes bewirkt, und zwar durch Einschiebung in die Aluminium-Sauerstoff-Bindung.Außerdem läuft die Polymerisation an katalytischen Koordinationsaggregaten, nach dem Prinzip “lebender” Systeme ab.
    Notes: Pure aluminum isopropoxide was shown to be a highly active catalyst for the polymerization of ε-caprolactone: the overall kinetics of this polymerization follow a first current order in monomer and a first order in catalyst.Mechanistical studies indicate also that this system operates through a selective acyloxygen cleavage of the lactone ring, with insertion in the aluminum-oxygen bond.Moreover, the polymerization proceeds by a perfectly “living” process on catalytic coordination aggregates.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975112
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  • 10
    Electronic Resource
    Electronic Resource
    Vacuum-Ultraviolet circular dichroism of Protected homo-oligopeptides derived from S-methyl-L-cysteine (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 941-947 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Monodispersed N-and C-protected linear homo-oligomers of S-methyl-L-cysteine (n = 2 - 7) are studied by measurements of circular dichroism in the vacuum-ultraviolet region. In the solid state higher members of the series take up a β-conformation. The results are compared with earlier circular dichroism and infrared absorption measurements on the same series, and also with the related norvaline and methionine series.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820325
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