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  • Wiley-Blackwell  (37)
  • Geological Society of London  (4)
  • 1970-1974  (41)
  • 1
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: In part I of this paper (1) we give evidence that the P23-capsoid of τ-particles is transformed in situ into the P23*-capsid of normal phage. Using the polymorphism of phage T4, we have chosen polyheads as representative of P23 assemblies and giant phages as representative of P23* assemblies in order to study their surface crystals by optical filtration of micrographs. We found for polyheads a lattice constant of 112 Å with the typical hexameric, ringlike capsomer and for the giants a lattice constant of 124 Å with quite a different capsomer morphology, of the type (6+1). From the stoichiometry of the proteins composing the normal capsid we conclude that the protomer is a single P23* molecule and that the minor capsid-proteins must be in singular positions on the surface lattice or on the polyhedral head (center of capsomers, vertices, or basal part).We extrapolate the findings on the giant head to the normal head and give a geometric model which is consistent with 1,100 molecules of P23* per capsid.We discuss the part of form inheritance contributed by P23 and the other formgiving gene products and give evidence that morphologic characters are the result of pairs of a reaction chain of interacting gene products. The example we give is the giant head produced by a ts mutant in gene 24 at 36°C.
    Additional Material: 10 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 1377-1385 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using Wilson's GF-matrix method as modified by Higgs for infinite helical polymers, dispersion curves and the frequency distribution function have been calculated for poly-L-proline II chain. Infrared spectrum is obtained and a Urey-Bradley force field, which provides best fit with the observed frequencies, is evaluated. The result are discussed from the viewpoint of the conformational characteristics of forms I and II.
    Additional Material: 3 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 657-678 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: On axial extension of polymer melts at constant deformation rates, the development of high-elastic deformation is of predominant importance during the initial period. High-elastic deformation is accompanied by a rise in viscosity and in the modulus of high-elasticity and by retardation of the relaxation processes in the region of large relaxation times. At relatively low deformation rates, the rise in viscosity and high-elasticity modulus and the retardation of relaxation processes may give way to a decrease in viscosity and high-elasticity modulus and acceleration of relaxation processes, so that stationary flow regimes are attained. The transition from strain regimes with increasing viscosity and modulus of high elasticity to those with a decrease of these quantities corresponds to an increase in the rate of accumulation of irreversible deformation. Accordingly, a competing influence due to the orientation effect and to destruction of the network of intermolecular bonds becomes evident while stationary flow is being attained. The orientation effect must be responsible for the retardation of the relaxation processes, whereas rupture of the intermolecular network bonds results in structural relaxation accelerating relaxation processes. In contrast to shearing, during extension the orientation effect is of predominant importance. Hence in stationary flow regimes the viscosity may not only remain independent of the rate of strain, but even increase with it. In this case the contribution of the large relaxation times to the relaxation spectrum increases with increasing stress in stationary flow regimes. The fact that the longitudinal viscosity and the modulus of high elasticity are independent of the stress in stationary flow regimes does not guarantee linearity of the mechanical properties of the polymer in the prestationary stage of deformation when complex changes occur in its relaxation characteristics. At high deformation rates the viscosity and the modulus of high elasticity keep rising with increasing deformation until rupture occurs. Determination of the strength of polystyrene samples vitrified after extension showed that it is due not to the entire degree of extension, but only to the value of accumulated high-elastic deformation. The strength of the vitrified samples is to a first approximation independent of the rate at which the melt was extended.
    Additional Material: 19 Ill.
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  • 4
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The kinetics of aminolysis of 1,2;3,4-meso-erythritol dicarbonate and 1,2;3,4;5,6-mannitol, sorbitol, and dulcitol tricarbonates by n-butylamine in dimethylformamide solution was investigated. The dicarbonate and tricarbonates are considered respectively as models of dyads and triads in the poly(vinylene carbonate) chain. The theoretical kinetic curves for the dimer and the trimers were calculated by solution of kinetic equations and close agreement with experiment was obtained. A version of the Monte-Carlo method was developed to provide a model for the reaction process by a computer calculation including the neighboring group effect in enhancing reactivity. The theoretical curve for a trimer coincides with the experimental one. These results confirm the accelerating influence of the unreacted neighboring groups. For the polymeric chain the experimental and calculated curves deviate for conversions beyond 10%. This indicates an additional polymer effect, which is as yet unexplained.
    Additional Material: 4 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2091-2098 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A complete normal coordinate analysis, infrared absorption, and inelastic neutron scattering studies on α-glycylglycine are reported. A Urey-Bradley force field which is also valid for N-deuterated sample is obtained. Assignments in the low-frequency region are based on inelastic neutron spectrum obtained in one phonon and cubic approximation.
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 11 (1972), S. 2099-2108 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A normal coordinate analysis for cyclic tetra-L-alanine molecule is reported. A comparison of amide modes and other low-frequency vibrations sensitive to conformational changes is made with those in poly-L-alanine. Intramolecular coupling coefficients are calculated using perturbation treatment.
    Additional Material: 3 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1965-1973 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Dispersion curves and frequency distribution for poly-L-hydroxyproline (PLHP) chain were obtained using Wilson's GF matrix method as modified by Higgs. These are compared with those of poly-L-proline II and polyglycine II, which also have three-fold screw symmetry. Ring and skeletal modes characteristic of PLHP are identified and the assignments of observed infrared and Raman frequencies are reported. Urey-Bradley force constants were evaluated.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 12 (1972), S. 317-322 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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 dependence of true stress on the extension ratio of PVC threads has been determined for a wide range of extension rates. Since the polymer subjected to deformation was in the high-elastic state (at temperatures from 90 to 160°), the deformations were predominantly high-elastic. The dependence of true stress on the amount of high-elastic deformation is described by the Mooney-Rivlin equation.Relaxation moduli have been found on the basis of measurements of stress relaxation at constant deformation after various extension ratios were attained at different rates. Within the limits of deformation regimes at which the true stress is an increasing function of extension ratio the relaxation moduli do not depend on extension ratio and rate of extension. This enables one to arrive at a master curve of the relaxation modulus versus relaxation time with the reservation indicated above concerning the increasing character of the dependence of true stress on extension ratio. The relaxation spectrum represented by the high-elasticity plateau has been determined from the relaxation moduli according to the first approximation.The experimental data for a very wide range of deformation regimes and temperatures are presented in the form of an invariant dependence of the ratio of true stress to the rate of deformation on the product of deformation time by extension ratio.The ultimate strength of the specimens frozen rapidly after the attainment of definite extension ratios is determined by the accumulated high-elastic deformation.
    Additional Material: 8 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 53 (1970), S. 569-576 
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Using pH-methods - direct titration according to Schwarzenbach, and ligand-ligand exchange - the stability constants of the complexes of divalent calcium, copper and zinc ions with the anions of triethylenetetramine hexaacetic acid have been determined. The complications arising by the interpretation of the experimental measurements of pH-values below 3.5 are discussed. These factors are normally not taken into account, and often wrong values of the equilibrium constants have been communicated.
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-2: Polymer Physics 8 (1970), S. 1-17 
    ISSN: 0449-2978
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An apparatus is described and a method discussed for determining the rheological characteristics of elastic liquids during extension at constant rates of deformation and extension. The material studied was polyisobutylene of molecular weight 7 × 104. At low constant deformation rates steady-flow regimes were achieved, with corresponding equilibrium high elastic strains. A detailed study has been made of the process of attainment of steady-flow regimes and it is shown that before steady flow is reached the curve of longitudinal viscosity versus strain passes through a maximum. As the rate of deformation rises, the strains at which steady-state flow regimes are achieved increase, and the time required to reach these regimes decreases. Qualitatively this occurs in the same way as upon shear. The dependence of equilibrium high-elastic strains (under steady-flow regimes) on the rate of deformation has been determined. At steady-flow regimes the stress depends linearly on the rate of deformation at low values of the stress. Under such conditions Trouton's formula is valid. At constant rates of extension the stress versus time curve passes through a maximum which becomes higher with increasing extension rates.
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