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  • Polymer and Materials Science  (161)
  • AERODYNAMICS  (83)
  • GENERAL
  • 1975-1979  (245)
  • 1977  (245)
  • 1
    Electronic Resource
    Electronic Resource
    Vibrational modes of A-DNA, B-DNA, and A-RNA backbones: An application of a green-function refinement procedure (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2491-2506 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Normal vibrational analysis was carried out for DNA molecules in both A and B conformations as well as for A-RNA. A simplified backbone model was examined and expanded to include the backbone phosphate-group and the ribose ring. We applied the new force-constant refinement procedure discussed in the preceeding paper [Van Zandt, L. L., Lu, K.-C. & Prohofsky, E. W. (1977) Biopolymers, 16, 2481-90] to fit some observed frequencies in the Raman spectra for all three nucleic acids with the same set of force constants. The results indicate that the observed frequency shift can be attributed to the conformational change solely. We ignored the second-order differences in force constants for the different geometries. The agreement between the observed and calculated frequencies derived from the final refined set of force constants is good and apparently justifies this assumption. Two modes previously assigned to the symmetric diester O-P-O stretch and the symmetric dioxy O‥P‥O stretch are actually fitted. They are mainly backbone phosphate-group modes. The refined ribose-ring force-constants were transferred to the calculation of the vibrational spectrum of tetrahydrofuran. The overall agreement is again good. We discuss these calculations and the resulting normal modes. We also discuss the application of the Green-function refinement scheme and several strategies adopted to bias the convergence of the procedure.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360161112
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  • 2
    Electronic Resource
    Electronic Resource
    Helix coil transitions of d (A)n·d(T)n, d(A-T)n·d(A-T)n, and d(A-A-T)n·d(A-T-T)n; evaluation of parameters governing DNA stability (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 1115-1137 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermally induced helix-coil transitions of three A-T DNAs, d(A)n·d(T)n, d(A-T)n·d(A-T)n, and d(A-A-T)n·d(A-T-T)n, were studied. Experimental transition curves of the DNAs were analyzed using the loop entropy model of DNA melting. The calculation of the melting curve of d(A-A-T)n·d(A-T-T)n is presented using the integral equation formalism of Goel and Montroll. The aim of this work was to evaluate thermodynamic parameters which govern DNA stability and to test the theoretical model employed in the analysis. Our results show (1) an excellent over-all agreement between theory and experiment, (2) a loop entropy exponent k = 1.55 ± 0.05 provided the best fit to all the polymer transition curves, (3) the evaluated stacking free energies reflect the relative stability of the DNAs, and (4) the stacking energies of the ApA·TpT dimer evaluated from d(A)n·d(T)n and d(A-A-T)n·d(A-T-T)n differ. The last result is consistent with different conformations for the dimer in these two polymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160512
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  • 3
    Electronic Resource
    Electronic Resource
    Branching and molecular weight distribution of polyethylene SRM 1476 (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 2833-2845 
    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: A method of determining the distribution of branching in a polymer is developed employing limiting viscosity numbers (intrinsic viscosity), gel permeation chromatography (GPC), and absolute molecular weight determinations of fractions of the whole polymer. A molecular weight calibration of the GPC column set is first determined empolying these fractions. From the limiting viscosity number measurements of these fractions and their molecular weight distribution determined from the GPC chromatogram, the viscosity-molecular weight relationship is determined by a nonlinear least-squares fitting procedure. For the same molecular weight, the limiting viscosity number of the branched polymer is less than the limiting viscosity number of the linear polymer. From the ratio of the two, the number of branches per unit molecular weight of the branched polymer is calculated. The method was applied to SRM 1476, the standard reference branched polyethylene issued by the National Bureau of Standards. The branching density for the constituents of SRM 1476 rise from zero at molecular weights less than 10,000 to about 6 to 8×10-5 at molecular weights of 50,000 and above. The branching of SRM 1476 was also determined by the method of Drott and Mendelson, giving a result in fair agreement with the above method.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070211019
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  • 4
    Electronic Resource
    Electronic Resource
    Inhibitoren der Korrosion 20(1)-Über die zeitliche Abhängigkeit der analytischen Zusammensetzung der Korrosionsprodukte des Eisens von der Menge an verbrauchtem Sauerstoff (1977)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 28 (1977), S. 478-480 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Analytical composition of the corrosion products of iron as a function of time and of the oxygen consumedUsing a modified standard method of analysis it is possible to analyze mixtures containing Fe0, Fe2+ and Fe3+. This method is used to study corrosion systems catalyzed by chlorides. According to the results obtained the amount of Fe2+ is approx constant at pH 7, irrespective of the oxygen quantityt consumed, Fe0 being oxidized to give Fe2+ and the latter being oxidized, at a comparable rate, to give Fe3+. At pH 3, however, Fe2+ is obtained almost exclusively, and beyond pH Fe3+ becomes predominating.
    Notes: Mit einer modifizierten Analysenmethode ist es möglich, Gemische mit Fe0, Fe2+ und Fe3+ zu analysieren. Diese Methode wird zur Untersuchung von Systemen mit chloridkatalysierter Korrosion benutzt. Nach den Ergebnissen ist die Fe2+-Menge bei Ph 7 unabhängig von der verbrauchten Sauerstoffmenge annähernd konstant, da Fe0 zu Fe2+ und dieses weiter zu Fe3+ oxidiert wird. Die Geschwindigkeiten dieser Reaktionen sind vergleichbar. Bei pH 3 erhält man nur Fe2 und ab pH 4 wird Fe3+ vorherrschen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19770280705
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  • 5
    Electronic Resource
    Electronic Resource
    A new procedure for refining force constants in normal coordinate calculations on large molecules (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 2481-2490 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We develop a force-constant refinement procedure which we believe capable of being used in problems of large molecules and biopolymers. The procedure is based on a Green-function expression which relates changes in frequency to changes in force constants. The method does not require that assignments be made before refinment (although they may be). An expansion of this expression gives rise to a set of linear algebraic equations for the force-constant corrections, rather than an equation involving residuals to minimize. The resulting calculations are considerably simpler. This approximate is iterated to find the final refined force-constants. We discuss several methods of improving the convergence of the procedure which take into account the experimental information which may be available. Of particular interest is a scheme to select the force constants to be refined by imposing a criterion for selecting those which will fit the experimental data with the smallest changes of the force constants from their expected values. We discuss some limitations which occur for all methods of refinement applied to large molecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360161111
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  • 6
    Electronic Resource
    Electronic Resource
    Antioxidants and stabilizers. LXVI. Oxidation and photooxidation of methyl- and octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionates. quenching of singlet oxygenPart LXV: L. Taimr and J. Pospíšil, this journal 52 (1976) 31. (1977)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 65 (1977), S. 197-210 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Cyclohexadienonhydroperoxide IIIb und IIIc entstehen durch methylenblau-sensibilisierte Photooxidation von Methyl-(IB) und Octadecylester (Ic) der 3-(3,5-Di-tert-butyl-4-hydroxyphenyl)propionsäure. Die Reaktion verläuft über den Singulett-Sauerstoff. Es wurde die photochemische Stabilität der beiden Hydroperoxide in Anwesenheit und Abwesenheit des Sensibilisators verfolgt. Beide Hydroperoxide spalten sich thermisch unter Bildung der Ausgangsphenole Ib bzw. Ic. Die verbindung IV, die einen wirksamen Quencher (Löscher) von Singulett-Sauerstoff darstellt, entsteht durch die Oxidation von Ib mittels Bleidioxid. Sie nähert sich in ihrer Wirkung dem β-Karotin. Die Verbindung IV ist gegen weitere Oxidation im neutralen Milieu beständig. E wurden die Umwand-lungen von Ib und Ic im Hinblick auf die Prozesse, die während der Alterung von stabilisierten Polyolefinen verlaufen, verfolgt.
    Notes: Photooxidation of the methyl ester (Ib) and octadecyl ester of 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid (Ic) sensitized with methylene blue gives rise to cyclohexadienone hydroperoxides IIIb or IIIc. The reaction proceeds via singlet oxygen. The photochemical stability of both hydroperoxides was examined in the presence and absence of sensitizer. The thermal decomposition of both hydroperoxides leads to the respective starting phenols Ib or Ic. Oxidation of Ib with lead dioxide yields IV, an effective quencher of singlet oxygen, the effect of which approaches that of β-carotene. In a neutral medium Iv is stable against oxidation. The transformations are investigated with respect to the system of processes occurring in the aging of stabilized polyolefins.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1977.050650114
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  • 7
    Electronic Resource
    Electronic Resource
    Vulcanization of butyl rubber by p-quinone dioxime (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 1771-1781 
    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 vulcanization of butyl rubber by p-quinone dioxime oxidized by red lead and tetrachloroquinone was investigated. The maximum physical effective crosslinking density of the vulcanizates appeared to be when p-quinone dioxime and the oxidizing agent were equimolar. The formation of one physical effective crosslink required one molecule of p-quinone dioxime. Chemical reactions are suggested for the vulcanization steps.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1977.070210705
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  • 8
    Electronic Resource
    Electronic Resource
    Analysis of bioglass fixation of hip prostheses (1977)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 11 (1977), S. 267-282 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The analysis of the bonding interface between hip prostheses and bone after functional use in animals was carried out. Scanning electron microscopy (SEM) with energy dispersive analysis (EDX), and Auger electron spectroscopy were used to evaluate the bonding interface. Various methods of postsacrifice sample preparation were used to evaluate the effect of such different methods on the analysis of the bonding interface. Comparison of the results with several rat tibia implant experiments is also presented.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820110211
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  • 9
    Electronic Resource
    Electronic Resource
    An in vitro and in vivo analysis of anodized tantalum capacitive electrodes: Corrosion response, physiology, and histology (1977)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 11 (1977), S. 637-656 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Oxidation-reduction reactions which can destroy high current-density metalstimulating electrodes are avoided when using capacitive electrodes. The results of in vitro and in vivo testing of anodized, high surface area, sintered tantalum electrodes are presented. The corrosion response of the electrodes is excellent; there is no evidence of dissolution of the electrode. A deposit forms on the surface of the electrodes, but has little effect on the voltage response to constant current stimulation. The physiological and histopathological results indicate the capacitive tantalum electrode to be the safest yet tested.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820110502
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  • 10
    Electronic Resource
    Electronic Resource
    Copolymers of vinylcyclohexane with styrene: Peculiarity of thermal behavior, parameters of crystal structure, and structural transitions (1977)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 15 (1977), S. 755-764 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Thermal behavior, the parameters of crystal structure, and the structural transitions of copolymers of vinylcyclohexane with styrene were studied. Heating in air of the copolymers and of mechanical mixtures of homopolymers results in thermooxidative destruction. For all samples, the oxidation starts at 210-220°C. The antioxidant effect on thermal stability of copolymers was studied. Differential thermal analysis (DTA) data were used to determine the melting points of homopolymers and crystal copolymers. The method of x-ray diffraction on large scattering angles was used to determine the dimensions and type of unit cells, the degree of crystallinity, the dimensions of the coherent scattering regions (the dimensions of crystallites) of copolymers of various compositions, and to compare them to the parameters of the structure of polyvinylcyclohexane and polystyrene. Information on molecular motion intensity and structural transitions in homopolymers and copolymers with changing temperature was obtained by the spin-probe technique.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1977.170150321
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