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  • Polymer and Materials Science  (213)
  • Physical Chemistry
  • 1985-1989
  • 1975-1979  (221)
  • 1979  (221)
  • 1
    Electronic Resource
    Electronic Resource
    Condensation of Co++ ions on chondroitin sulfate from transport coefficients and proton NMR measurements in aqueous solutions (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 1849-1857 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The “condensed” counterions which characterize high-charge-density polyelectrolyte solutions can be analyzed into two subpopulations: (1) site-bound counterions and (2) atmospherically entrapped counterions. The distinction is achieved experimentally by combining the data from self-diffusion coefficient or electrical mobility measurements, which give the amount of “condensed” ions, and those from nmr, chemical shift measurements, which indicate the amount of site-bound ions. In the case of a solution of chondroitin sulfate with excess Co++ counterions, it can be estimated that 20% of the structural charge of the polyion is neutralized by site-bound, dehydrated, condensed counterions, while a further 30% is neutralized by atmospherically entrapped, hydrated counterions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180803
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  • 2
    Electronic Resource
    Electronic Resource
    Collisional deactivation of O2(1Σg+) (1979)
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 11 (1979), S. 175-185 
    Details
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Relaxation rates for O2(1Σg+) by nonradiative pathways have been determined using the fast-flow technique. O2(1Σg+) is formed from O2(1Δg) by an energy pooling process. O2(1Δg) is generated by passing purified oxygen through a microwave discharge. Oxygen atoms are removed by distilling mercury vapor through the discharge zone. It has been observed that the wall loss rate for O2(1Σg+) decreases with increasing pressure of oxygen and thus appears to be diffusion controlled. Quenching rate constants for O2, N2, and He have been determined and found to be (1.5 ± 0.1) × 104, (1.0 ± 0.05) × 106 and (1.2 ± 0.1) × 105 l./mol·sec, respectively.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/kin.550110209
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  • 3
    Electronic Resource
    Electronic Resource
    Kurzzeitprüfmethoden zur Untersuchung des Einflusses von Wärmebehandlung und chemischer Zusammensetzung auf die Korrosionsbeständigkeit martensitischer Chrom-Nickel-(Molybdän)-Stähle mit tiefem Kohlenstoff-Gehalt (1979)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 30 (1979), S. 341-357 
    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: Short-duration test for evaluating the influence of heat-treatment and chemical composition on the corrosion resistance of low carbon martensitic chromium nickel (molybdenum) steelsThe following procedures were examined and compared for their suitability as rapid corrosion tests in comparative investigations on the influence of heat treatment and other production parameters on martensitic chromium-nickel-(molybdenum) steels of low carbon content: -Measurement of the mass loss in boiling 20% acetic acid, and in some cases 5% nitric or 1% hydrochloric acid.-Immersion in sulphuric acid/copper sulphate solution (modified Strauss test).-Current density/voltage curves in 1 N sulphuric acid.-Measurement of pitting potential und activation pH in 3% sodium chloride solution (on limited scale).The test materials employed contained 0.032-0.082% carbon, 11.6-16.4% chromium, 3.8-5.9% nickel and 0.31-1.6% molybdenum.The most suitable testing procedures were selected according to the steel type. Up to a mass loss rate of ≥ 0.05 mg · cm-2 · h-1 (materials with resistance inferior to steel type 13-6-1) the acetic acid test provides an excellent basis for comparison. Provided the optimal testing temperature is adopted, current density/voltage curves and immersion in sulphuric acid/copper sulphate solution yield usable results with all steel types investigated. The value of the information yielded by the test procedures is generally enhanced by metallographic characterization of the corroded surfaces; in particular the localization of chromium-depleted structure zones is made possible by this.
    Notes: Folgende Verfahren wurden auf ihre Eignung als Korrosionsschnelltest für vergleichende Untersuchungen zum Einfluß von Wärmebehandlungs- und anderen Herstellungsparametern bei martensitischen Chrom-Nickel-(Molybdän)-Stählen mit tiefem Kohlenstoffgehalt geprüft und einander gegenübergestellt: -Massenverlustmessung in siedender 20%iger Essigsäure und z.T. in 5%iger Salpeter-bzw. 1%iger Salzsäure-Auslagerung in Schwefelsäure-Kupfersulfat-Lösung (modifizierter Strausstest)-Stromdichte-Spannungskurven in 1 N Schwefelsäure-Lochfraßpotential- und Aktivierungs-pH-Messungen in 3%iger Natriumchloridlösung (in beschränktem Umfang).Als Testmaterial dienten Werkstoffe mit 0,032-0,082% Kohlenstoff, 11,6-16,4% Chrom, 3,8-5,9% Nickel und 0,31-1,6% Molybdän.Die günstigsten Prüfverfahren sind je nach Stahltyp auszuwählen. Der Essigsäuretest ergibt bis zu einer Massenverlust rate von ≥ 0,05 mg · cm-2 · h-1 (Werkstoffe mit niedrigerer Beständigkeit als Stahltyp 13-6-1) eine hervorragende Vergleichsbasis. Stromdichte-Spannungskurven sowie Auslagerung in Schwefelsäure-Kupfersulfat-Lösung bei optimal gewählter Prüftemperatur liefern bei allen untersuchten Stahltypen brauchbare Ergebnisse. Durch metallographische Charakterisierung der korrodierten Oberflächen wird die Aussagekraft der Testmethoden allgemein erhöht, wobei insbesondere die Lokalisation chromverarmter Gefügebereiche ermöglicht wird.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19790300505
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  • 4
    Electronic Resource
    Electronic Resource
    Conformation and properties of DNA-(Lys33, Leu67)100-(Orn)20 complex: A nucleohistone model (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 9-24 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis and characterization of the block copolypeptide (Leu67, Lys33)100Orn20, a synthetic model of histone, are reported. In neutral aqueous solutions, 80% of the etheropolypeptide block assumes an α-helical conformation, whereas the polyornithine block is in a random-coil conformation. In the association complexes with DNA, melting and titration experiments, as well as CD results, indicate that the polyornithine block interacts with DNA, whereas at least 2/3 of the lysine residues of the (Leu, Lys) moiety are excluded from the direct binding with DNA. CD spectra of the association complexes reveal significant differences from those obtained with DNA-polyornithine and DNA-polylysine complexes but substantial similarities with CD spectra of native and reconstituted nucleohistones. In contrast to DNA-polyornithine complexes, the CD spectra of the ternary complexes, copolypeptide-DNA-ethidium bromide, indicate a strong reduction of the dye intercalation. The low-angle x-ray diffraction pattern, reminiscent of that of chromatin, reveals the presence of a superstructure in these complexes. The results obtained are discussed in connection with the expected structural features of the model.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180103
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  • 5
    Electronic Resource
    Electronic Resource
    Conformational characteristics of the trinucleoside diphosphate d(ApApA) from energy-minimization studies (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 789-804 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Energy-minimization studies were carried out on the trinucleoside diphosphate d(ApApA). The potential energy contributions from nonbonded, electrostatic, hydrogen-bonding, and torsional interactions were minimized by treating the 13 relevant dihedral angles as simultaneous variables. For the C(3′)-endo trimer, 14 low-energy conformations are within 10 kcal/mol above the lowest energy found, compared to only 3 in the case of the C(2′)-endo trimer. This result shows the flexible character of the C(3′)-endo unit. The hairpin-type, loop-promoting conformer with (ω′,ω) = (101°, 59°) was found to be the most favored structure at the 3′-terminus of d(ApApA).The predicted U- and L-type bend conformers were found to lie within 5 kcal/mol, compared to the lowest energy B-DNA structure. The A-DNA and Watson-Crick DNA types of helical conformers also lie within very small energy barriers. The phosphate group at the 5′-end of the nucleotide residue has a definite influence on the base of the corresponding nucleotide, keeping it in the normal anti-region, and hence on the base-stacking property. The results are compared with the presently available experimental data, mainly with the tRNAPhe crystal.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180405
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  • 6
    Electronic Resource
    Electronic Resource
    Solvent accessibility study on tRNAPhe (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2233-2247 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In order to assess the solvent-solute association in the tRNAPhe molecule, solvent accessibility calculations were carried out for its crystalline and completely extended states following the method of Lee and Richards. To do this, results from the calculations on model trinucleotide systems pApXpA with different bases at position X were used. In the folded form of the molecule, it was found that the oxygen atoms O(I) and O(II) of almost all the phosphate groups and the O(2′) atoms of the sugar rings situated throughout the backbone were highly exposed to the solvent. The amount of reduction found in the solvent accessibilities of the various atoms in going from the extended state to the folded state of the molecule indicates the kind of compactness of the tertiary structure in tRNAPhe. The results give quantitative support to many characteristics of the tRNA molecule, such as loop sections, buried/exposed residues, hydrophobic interactions, etc., which were thought to be due to other factors.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180911
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  • 7
    Electronic Resource
    Electronic Resource
    The effect of counter-ion substitution on the transport properties of polyelectrolyte solutions (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 187-201 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effects of counter-ion substitution in aqueous polyelectrolyte solutions (chondroitin sulfate) on the two main transport phenomena of the ionic species, self-diffusion and electrical mobility, were studied experimentally by tracer methods and dynamic light scattering. The data were analyzed with respect to counter-ion condensation and stoichiometric substitution of low-ionic counterions by high-ionic charge ones and compared to Manning's theory. Substitution effects on the apparent charge of the macro-ion were derived from the transport data using an extended Nernst-Einstein relationship and discussed in the light of the condensation effect in polyelectrolyte solutions. The effective charge of the polyion (i.e., its residual charge after condensation of counter-ions) and the charge difference between the substituting counter-ions appear determinant in the mechanism of substitution.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180114
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  • 8
    Electronic Resource
    Electronic Resource
    Thermally stimulated currents in thiourea formaldehyde polymers (1979)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 82 (1979), S. 39-53 
    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: Thioharnstoff-Formaldehyd-Polymere wurden durch Kondensation von Thioharnstoff mit Formaldehyd unter alkalischen Bedingungen synthetisiert und durch Infrarotspektroskopie charakterisiert. Die Stabilität der Proben wurde durch thermogravimetrische Analyse bestimmt. Es wurden Elektrete hergestellt, indem das Polymere bei 100-300 kV · m-1 und bei 303-353 K polarisiert wurde. Die komplexen thermischen Depolarisationsspektren wurden aufgezeichnet und analysiert. Die Ergebnisse wurden korreliert mit Untersuchungen über die Abhängigkeit der Dielektrizitätskonstante und der Gleichstromleitfähigkeit von der Temperatur.
    Notes: Thiourea formaldehyde polymers were synthesized by condensing thiourea with formaldehyde under alkaline conditions and were characterized by infrared spectroscopy. The stability of the samples was determined by thermogravimetric analysis. Electrets were prepared by polarizing the polymer at 100-300 kV m-1 and at 303-353 K. The complex thermal depolarization spectra were recorded and analysed. The results are correlated with studies on the variation of the dielectric constant and d. c. conductance as a function of the temperature.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1979.050820104
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  • 9
    Electronic Resource
    Electronic Resource
    Environmental stress cracking of polyethylene: Temperature effect (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 1167-1179 
    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: Polyethylene was drawn at temperatures ranging from 30° to 60°C in aggressive and nonaggressive environments. Fibrillation was found to occur in the aggressive environment, and this effect increased with temperature. The temperature effect was more prominent at lower strain rates. Thin films drawn in aggressive environments deformed inhomogeneously. Again, this effect was found to increase with increasing temperatures. Single crystal deformation was also found to be inhomogeneous, and “solvation” of the amorphous surface layer occurred in the presence of the aggressive environment. Infrared measurements of sorption under different loads indicated that there is an increase in the amount of sorbed materials with increasing load. Dynamic mechanical studies revealed the intracrystalline regions to be affected preferentially.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230420
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  • 10
    Electronic Resource
    Electronic Resource
    The interaction of hydrogen sulfide with lead- and barium-cadmium-zinc-stabilized poly(vinyl chloride) (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 1769-1779 
    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: Poly(vinyl chloride) polymers stabilized with tribasic lead sulfate discolor upon exposure to hydrogen sulfide gas as a result of lead sulfide formation. The discoloration occurs for samples in both cord and sheet forms and is shown to be a function of total H2S exposure, reaching a limiting value that is determined by the amount of lead stabilizer used in the polymer formulation. The permeation and diffusion constants for H2S through PVC stabilized with tribasic lead sulfate and with a liquid Ba-Cd-Zn formulation are found to be PPb = (6.0 ± 0.2) × 10-9, PBaCdZn = (5.2 ± 0.2) × 10-9 (both in cm3 gasċcm film/cm2 areaċsecċcm Hg), DPb = (1.3 ± 0.2) × 10-7 cm2/sec, and DBaCdZn = (6.4 ± 0.6) × 10-8 cm2/sec, all measured at 21°C. The stabilizing efficiencies of the formulations were assessed by HCl evolution measurements, which show that exposure to H2S decreases the initial polymer stability for both Pb-stabilized and Ba-Ca-Zn-stabilized formulations. Protection of stabilized PVC formulations from diffusing hydrogen sulfide is thus advisable for long-term stability as well as for color integrity.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230617
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