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  • 1985-1989  (24)
  • Analytical Chemistry and Spectroscopy  (15)
  • Polymer and Materials Science  (9)
  • 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
    Rapid identification of drug metabolites with tandem mass spectrometry (1988)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 15 (1988), S. 193-204 
    Details
    ISSN: 0887-6134
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A method which involves the use of tandem mass spectrometry (MS/MS) for the identification of drug metabolites has been demonstrated with a triple quadrupole mass spectrometer. The method is based on the fact that metabolites usually retain various substructures of the original drug molecule. MS/MS is capable of rapidly identifying molecules with characteristic substructures without prior separation. It is shown that this method makes it possible to postulate possible drug metabolite structures rapidly and systematically without the use of standards. The MS/MS method, as it was applied to the identification of the metabolites of a new antiepileptic drug, zonisamide, is discussed. In this case it was possible to identify isomeric metabolites due to their differences in vaporization times off the probe and their different daughter spectra. The complementary uses of the neutral loss and parent scans for the determination of the site of metabolism is demonstrated. A new figure of merit, the limit of identification, is introduced. The amount of the epoxide metabolite of carbamazepine necessary for its reliable identification in urine was shown to be 0.4 ng/μl. The application of various techniques to confirm preliminary findings with this MS/MS method are described.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200150403
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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
    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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  • 7
    Electronic Resource
    Electronic Resource
    Formation of the bicarbonate anion from deprotonated oxalic acid (1988)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 275-276 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290021207
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  • 8
    Electronic Resource
    Electronic Resource
    Do the benzyl and silabenzyl anions show similar ion chemistry in the gas phase? (1989)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 3 (1989), S. 293-294 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The ion PhSiH2- undergoes a number of fragmentations upon collisional activation, including losses of H·, H2 (mainly to form PhSi-), and SiH2, together with formation of HSi-. The ion/molecule chemistry of PhSiH2- is characteristic of silyl anion systems and bears no analogy to that of benzyl anion reactions; for example with N2O and CO2 it forms Ph(H)2SiO- as the sole ionic product, while with CS2 it yields Ph(H)2SiS-.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290030905
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  • 9
    Electronic Resource
    Electronic Resource
    Analysis of inositol mono- and polyphosphates by gas chromatography/mass spectrometry and fast atom bombardment (1986)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 13 (1986), S. 333-341 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electron ionization spectra of all of the positional isomers of myo-inositol monophosphate and of myo-inositol 1,2-cyclic phosphate were obtained by gas chromatography/mass spectrometry of the pertrimethylsilyl derivatives. The fragmentation pattern of pertrimethylsilyl myo-inositol-1-phosphate was studied using deuterium labeling. The phosphate moiety was found to direct fragmentation to produce fragment ions of useful intensity with specific carbon retention. The spectrum of pertrimethylsilyl myo-inositol-1,4-bisphosphate is also described. An electron impact gas chromatographic/mass spectrometric method for myo-inositol-1-phosphate has been developed, which has a sensitivity to a level of 0.1 pmol. The positive and negative ion fast atom bombardment spectra of myo-inositol hexakis(disodium phosphate) and myo-inositol hexakis(dihydrogen phosphate) are described. The lesser-phosphorylated inositol polyphosphates were also studied, including inositol pentakis and inositol tetrakis(dihydrogen phosphates) as well as D-myo-inositol-1,4,5-trisphosphate and D-myo-inositol-1,4-bisphosphate from human red blood cells. The sensitivity of fast atom bombardment for the measurement of the latter two substances allows their detection to a level of about 10 nmol. The fast atom bombardment spectrum of synthetic myo-inositol 1,2-cyclic phosphate revealed variable amounts of a dimer produced during its preparation.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200130704
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  • 10
    Electronic Resource
    Electronic Resource
    Structure of fibrous cellulose acetate: X-ray diffraction, positron annihilation and electron microscopy investigations (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 95-106 
    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: X-ray diffraction, positron annihilation, electron microscopy and bulk density measurements are reported as a function of the degree of acetylation for a linters cotton. Heterogeneous reaction proceeds with a retention of ordered structure in the fibers. Substitution does increase the extent of disorder but is not sufficiently extensive to disrupt completely order at the fiber, fibril, micro fibril, and crystallite levels. The generation of disorder is associated with an increase in the interfibrillar distance, a breakup of the microfibrillar structure without a total disruption of the microcrystalline structure.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330109
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