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  • 1985-1989  (9)
  • 1980-1984  (8)
  • 1965-1969  (2)
  • 1960-1964  (6)
  • Polymer and Materials Science  (25)
  • 1
    Electronic Resource
    Electronic Resource
    Multiple denaturational transitions in fibrillar collagen (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 1875-1893 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The heat denaturation of pepsinized bovine nonfibrillar and fibrillar collagen was studied by differential scanning calorimetry. For fibrillar preparations that had been rapidly precipitated with stirring at low ionic strength, then resuspended at physiological ionic strength, multiple denaturational transitions were observed. At heating rates of 10°C/min, melting endotherms occurred at about 44, 50, 53, and 57°C. Fibrillar collagen that was slowly gelled without stirring at physiological ionic strength exhibited a similar series of endotherms, but the lower melting transitions were less conspicuous. In contrast, nonfibrillar bovine collagen in acidic solution showed only a single denaturational transition at 40°C. Nonfibrillar solutions at pH 7, to which inhibitors of fibrillogenesis were added, showed a major endotherm as high as 46°C. These results suggest that reconstituted fibrillar collagen contains a heterogeneous fibril population, possibly including molecules in a nonfibrillar state. It was proposed that the multiple melting endotherms of such preparations were due to sequential melting of molecular and fibril classes, each with a distinct melting temperature. The fibrillar classes may represent three or more types of banded and nonbanded species that differ from each other in packing order, collagen concentration, and possibly also in fibril width and level of cross-linking.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360251006
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  • 2
    Electronic Resource
    Electronic Resource
    The sieving of spheres during agarose gel electrophoresis: Quantitation and modeling (1989)
    New York : Wiley-Blackwell
    Biopolymers 28 (1989), S. 1475-1484 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By use of agarose gel electrophoresis, the sieving of spherical particles in agarose gels has been quantitated and modeled for spheres with a radius (R) between 13.3 and 149 mm. For quantitation, the electrophoretic mobility has been determined as a function of agarose percentage (A). Because a previously used model of sieving [D. Rodbard and A. Chrambach (1970) Proc. Natl. Acad. Sci. USA 65, 970-977] was found incompatible with some of these data, alternative models have been tested. By use of an underivatized agarose, two models, both based on the assumption of a single effective pore radius (PE) for each A, were found to yield PE values that were independent of R and that were in agreement with values of PE obtained independently (PE = 118 nm × A-0.74): sieving by altered hydrodynamics in a cylindrical tube of radius, PE, and sieving by steric exclusion from a circular hole of radius, PE. The same analysis applied to a 6.5% hydroxyethylated commercial agarose yileded a steeper PE vs A plot and also agreement of the above tow models with the data. The PE vs A plot was significantly altered by both further hydroxyethylation and factors that cause variation in the electro-osmosis found in commercial agarose.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360280811
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  • 3
    Electronic Resource
    Electronic Resource
    Investigation of cure in epoxy resins: Ultrasonic and thermally stimulated current measurements (1982)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 27 (1982), S. 4283-4294 
    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: Acoustic and thermally stimulated current measurements are reported as a function of cure for dicyanodiamide cured epoxy resins. It is found that the acoustic propagation is dominated by the generation of voids and does not directly reflect the extent of cure. In contrast, the thermally stimulated data correlate well with conductivity data, the amplitude of the space charge peak decreasing with increasing degree of cure and the dipole peak shifting to high temperatures as predicted from DSC data. Both methods exhibit potential as NDT methods for cure in resins.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1982.070271119
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  • 4
    Electronic Resource
    Electronic Resource
    13C-NMR spectra of cis-polymyrcene and cis-polyfarnesene (1988)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 26 (1988), S. 71-77 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Homopolymers of myrcene and farnesene were prepared anionically in pure cyclohexane. The microstructure, determined from an analysis of the 13C-NMR spectrum and spin-lattice relaxation times, indicates the polymers are at least 85% cis-1,4, 10% cis-3,4, and under 3% trans-1,4.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1988.080260107
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  • 5
    Electronic Resource
    Electronic Resource
    Potentiometric selectivity study of crown ethers containing four ring oxygen atoms and benzoxymethyl or carboxylic acid side chains as ionophores for lithium and potassium (1989)
    Weinheim : Wiley-Blackwell
    Electroanalysis 1 (1989), S. 63-67 
    Details
    ISSN: 1040-0397
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five crown ethers with four ring oxygen atoms and different types of pendant groups were used to prepare ion-selective electrodes by coating a membrane containing the crown ether on the tip of a silver wire incorporated in a flow cell. A flow injection analysis study was conducted to determine the potentiometric selectivities of the crown ethers for lithium, sodium, potassium, magnesium, and calcium ions. It was found that crown ethers with neutral side arms show selectivities for lithium over other ions, while those of acidic side arms show selectivities for potassium over the other ions. The effect of the addition of trioctylphosphine oxide to the electrode matrix was also investigated. A comparison is made between the potentiometric selectivities of the crown ethers for certain metal ions and their selectivities in extracting the ions into an organic phase.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/elan.1140010110
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  • 6
    Electronic Resource
    Electronic Resource
    Bifunctional reagents and protein structure determination. The reaction of phenolic disulfonyl chlorides with lysozymeThis work was supported in part by grants from the National Science Foundation (GA-9794 and G-16161) and from the American Academy of Arts and Sciences. (1964)
    New York : Wiley-Blackwell
    Biopolymers 2 (1964), S. 349-360 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It was established that phenol-2,4-disulfonyl chloride and α-naphthol-2, 4-disulfonyl chloride introduce new intramolecular or tertiary bonds into lysozyme. The phenolic hydroxyl group seems to make the cross linking reagents soluble in aqueous media; it was established that a sulfonylating; species does dissolve prior to hydrolysis but that the chlorosulfonyl groups are hydrolyzed within seconds of dissolution. New covalently linked residues were shown to be introduced by different, spectra. Peptide maps of the lysozyme treated with phenol-2,4-disulfonyl chloride. peroxidized, and digested with trypsin showed definite deletions and additions when compared with the control. Partial analysis of the peptides showed that cross linking between ε-amino groups of lysine residues had occurred. A certain degree of stabilization of lysozyme to inactivation by certain inactivating conditions was noted after treatment with the two reagents. Ultra-centrifugal analysis of the lysozyme treated with phenol-2,4-disulfonyl chloride showed that there was no detectable fraction having a higher molecular weight than native lysozyme. Tentative assignments of positions of cross linking were made.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1964.360020406
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  • 7
    Electronic Resource
    Electronic Resource
    Polyelectrolyte effects on site-binding equilibria with application to the intercalation of drugs into DNA (1984)
    New York : Wiley-Blackwell
    Biopolymers 23 (1984), S. 2671-2714 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A theory of polyelectrolyte effects on site-binding equilibria is generalized to multivalent ligands, multivalent supporting salt, intercalation, and multiple-site exclusion. The theory, which contains no adjustable parameters, except the number of sites excluded by a bound ligand, gives the dependence of the equilibrium constant on the binding fraction and the salt concentration. The theory is compared with prior experimental data for the dissociation of poly(acrylic acid), the binding of magnesium to polyphosphate, and the binding of ethidium and actionomycin D to DNA. The theory predicts the binding fraction dependence of the dissociation constant of poly(acrylic acid) well. The theory predicts the binding fraction dependence of the association constant of the binding of Mg2+ to polyphosphate well, if either one or two phosphates are bound by a magnesium ion. We conclude that polyelectrolyte effects on drug-DNA equilibria must be substantial. It follows that an incorrect estimate of the number of sites excluded by a bound drug molecule (because of its size or some other nonpolyelectrolyte effect) can be obtained from binding data if polyelectrolyte effects are ignored. The estimate is also within the context of, and subject to the validity of, the model used to describe the nonpolyelectrolyte contribution to binding. Our results suggest that, subject to these conditions, the anticooperativity of the binding of ethidium to DNA might be explained solely in terms of polyelectrolyte effects, and without reference to multiple-site exclusion, if sequence-specificity effects can be safely ignored. Our results also suggest that as few as two base pairs might be excluded by an actinomycin molecule. The theory gives fairly good agreement for the salt-concentration dependence of the association constant of all of the systems studied, including the complex of the neutral drug actinomycin with DNA.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360231202
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  • 8
    Electronic Resource
    Electronic Resource
    Morphology and cation local structure in a blend of copper-neutralized carboxy-terminated polybutadiene and poly(styrene-co-4-vinylpyridine) (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 27 (1989), S. 1911-1925 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Carboxy-terminated polybutadiene neutralized with Cu2+ (CuPBD) and its blend with poly(styrene-co-4-vinylpyridine) (SVP) were examined by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), and extended x-ray absorption fine structure (EXAFS) spectroscopy. The DSC results indicate that in the blend substantial mixing occurs in the CuPBD-rich phase, although complete miscibility is not achieved, and the SVP-rich phase remains relatively pure. The TEM micrographs indicate that the morphology, while irregular, is reasonably described as bicontinuous, with a domain size of order 100 nm. The SAXS patterns show that the ionic aggregates present in CuPBD are destroyed upon blending, which is interpreted as being due to steric hindrances between ionic groups coordinated to vinylpyridine nitrogens. The EXAFS radial structure function of the blend exhibits a marked decrease in the Cu-Cu peak in comparison with CuPBD, indicating a change in local structure upon blending. The results indicate that some of the SVP is miscible with CuPBD owing to complexation between the pendant pyridine groups and the Cu2+ ions, which disrupts the ionic aggregates. However, the two materials are not fully miscible, leading to a rather coarse two-phase morphology.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1989.090270909
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  • 9
    Electronic Resource
    Electronic Resource
    Refractive indices of monomer-polymer mixtures of vinyl formate, vinyl acetate, vinyl propionate, and vinyl butyrate (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 7 (1963), S. 783-787 
    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: Monomers of vinyl formate, vinyl acetate, vinyl propionate, and vinyl butyrate were carefully purified by distillation in a Vigreux column and in a 56-plate glass helixpacked Todd column. The refractive indices and boiling points of the purified monomers agreed with those given in the literature. The purified samples were exposed to the radiation of a quartz mercury lamp in order to produce several per cent polymer. The refractive indices are tabulated and plotted in graphs.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1963.070070230
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  • 10
    Electronic Resource
    Electronic Resource
    Electrical conductivity of polypropylene (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 7 (1963), S. 1015-1022 
    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 steady-state (d.c.) electrical conductivity of polypropylene has been measured as a function of temperature (25-150°C.) and field strength (0-94 kv./cm.). The temperature coefficient of the conductivity is 34.6 kcal./mole expressed as an activation energy. This is much larger than the activation energy for diffusion of small molecules in the same polymer. Thus, ionization rather than diffusion appears to be the primary activation process. The conductivity is nonohmic; the conductance quotient is a linear function of field strength but is larger than predicted by Onsager's theory. The ion “jump distance” as evaluated from the isothermal field dependence, is the same order of magnitude as the diffusional mean free path estimated from diffusion studies in other polymers. The conductivity, conduction activation energy, and field dependence appear to be relatively insensitive to polymer crystallinity.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1963.070070318
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