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  • 1990-1994  (5)
  • Chemistry  (4)
  • AChE  (1)
  • Antibiotics
  • Bi garnets increased superexchange
  • Coated vesicles
  • 1
    Electronic Resource
    Electronic Resource
    Electrostatic forces at helix-coil boundaries in DNA (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 393-405 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The Tm of internal loop-forming (dA · dT)N domains in pBR322 DNA has been measured over a tenfold range of [Na+]. The slopes SN = dTm/d log[Na+] are linear and decrease in magnitude with decreasing loop size N, signaling a reduction in Na+ released during the transition of these domains to the coil state. Values of SN decrese linearly with increasing N-1 in accordance with the expectation of a simple model for the occurrence of a gradient of long-range electrostatic forces at helix-coil boundaries, and extrapolate almost precisely to the value of S∞ observed for (dA · dT)∞. These results indicate (1) less counterion is released per phosphate residue from the finite loop than from the infinitesized loop, and (2) the difference in binding is constant for each boundary formed and independent of the size of the loop within the range examined: ∼ 350 base pair (bp) 〉 N 〉 71 bp. The slope of the dependence of SN on N-1 indicates the region of higher charge density at the boundary extends at least 18 Å into the coil and probably 40-50 Å before dropping to a value characteristic of the unperturbed coil. The free energy for excess counterion binding at boundaries can be expressed by \documentclass{article}\pagestyle{empty}\begin{document}$$ {{ - \Delta G} \mathord{\left/ {\vphantom {{ - \Delta G} {RT}}} \right. \kern-\nulldelimiterspace} {RT}} = 10.47{\rm log}\left[{{\rm Na}^ + } \right] + 5.234 $$\end{document} When the loop entropy function in a statistical mechanical algorithm for the dissociation of DNA is weighted by this quantity, calculated Tm are seen to vary by only ±0.09°C from observed.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290211
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: Nature of transformation products of dithiophosphates. II. Antioxidant action of thiophosphoryl disulphides (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 1297-1305 
    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 nature of transformation products of high-temperature reactions of thiophosphoryl disulphides with hydroperoxides in the absence and presence of oxidisable substrates and the role of the disulphide in the overall antioxidant mechanism was investigated using a range of techniques such as oxygen absorption, 31P nuclear magnetic resonance (NMR), gas-liquid chromatography (GLC), and peroxide determination. The major transformation products of the above oxidation reactions were found to be the thio and thiono-phosphoric acids, in addition to mono and polysulphides. At high molar ratios of peroxide to disulphide (〉10), these oxidation products are the main catalysts for peroxide decomposition, while at lower ratios the disulphide itself was found to play a major role in the antioxidant mechanism.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440720
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  • 3
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: Nature of transformation products of dithiophosphates. Part III. The antioxidant action of dithio and thio/thionophosphoric acids (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 50 (1993), S. 1823-1831 
    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 nature of transformation products of dithio- and thionophosphoric acids in the presence and absence of hydroperoxides and their role as transformation products formed during oxidation of thiophosphoryl disulfide at high temperatures is investigated. The major transformation product of dithiophosphoric acid was found to be the corresponding disulfide while thiophosphoric acid was the major oxidation product of the reaction of thionophosphoric acid with hydroperoxide. In the case of thiophosphoryl disulfide, it is shown that thionophosphoric acid was found to be one of the major transformation products in the presence of hydroperoxides, whereas no acids were formed in the absence of added hydroperoxides. © 1993 John Wiley & Sons, Inc.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070501019
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  • 4
    Electronic Resource
    Electronic Resource
    Mechanisms of antioxidant action: Photoantioxidant activity of polymer-bound hindered amines. II. Bis acrylates (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 1287-1296 
    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: 1-Acryloyl-4-acryloyloxy-2,2,6,6-tetramethylpiperidine (AATP) has been covalently attached to polypropylene under conditions of reactive processing to give substantial concentrations of essentially 100% grafted antioxidant (AATP-B). Solution of the concentrates showed that at high concentration of grafted antioxidant some homopolymerized AATP was present and the polymer undergoes transient cross-linking during processing. Concentrates of bound AATP (AATB-B) when used as conventional additives for polypropylene are very effective photoantioxidants due to conversion to the related polymer-bound nitroxyl radicals by photosensitized oxidation. A typical commercial hindered phenol, Irganox 1076, when used at low concentration in combination with -B also acts as a photosensitizer for nitroxyl formation. Unlike low molar mass-hindered piperidinoxyl, polymer-bound nitroxyls are effective thermal antioxidants that synergize very effectively with low concentrations of Irganox 1076.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070440719
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  • 5
    Electronic Resource
    Electronic Resource
    Biochemical and morphological differentiation of acetylcholinesterase-positive efferent fibers in the mouse cochlea (1990)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 15 (1990), S. 123-143 
    Details
    ISSN: 0741-0581
    Keywords: AChE ; ChAT ; Immunoreactivity ; Electron microscopy ; Acetyltransferase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We have compared the biochemical expression of cholinergic enzymes with the morphological differentiation of efferent nerve fibers and endings in the cochlea of the postnatally developing mouse. Choline acetyltransferase (ChAT) and acetylcholinesterase (AChE) are present in the newborn cochlea at specific activities 63% and 25%, respectively, of their mature levels. The relative increases in ChAT, in AChE, and in its molecular forms over the newborn values start about day 4 and reach maturity by about day 10. The biochemical results correlate well with the massive presence of nerve fibers stained immunocytochemically for ChAT and AChE or enzymatically for AChE in the inner and outer hair cell regions. Ultrastructural studies, however, indicate the presence of only few vesiculated fibers and endings in the inner and outer hair cell regions. The appearance of large, cytologically mature endings occurs only toward the end of the third postnatal week. The discrepancy may be resolved in the electron microscope using the enzymatic staining for AChE. Labeling is seen on many nonvesiculated fibers and endings in the hair cell regions, suggesting that the majority of the efferent fibers in the perinatal organ may be biochemically differentiated but morphologically immature. The results may imply that the efferents to inner and outer hair cells develop earlier than indicated by previous ultrastructural studies. Moreover, the pattern of development suggests that in the cochlea, as in other tissues, the biochemical differentiation of the efferent innervation may precede the morphological maturation.
    Additional Material: 25 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060150205
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