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  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 13 (1974), S. 1573-1605 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The dependence of Förster long-range resonance energy transfer efficiency on the orientational freedom of donor D and acceptor A molecules attached to a macromolecular substrate is examined. The usefulness of polarized emission measurements in determining the mutual orientation as well as the degree of orientational freedom of D and A and thereby deriving maximum and minimum values for the D-A separation from the transfer efficieny is demonstrated.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 175 (1974), S. 2705-2718 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Oriented fibers of polypivalolactone (PPL) were melted in a differential scanning calorimeter. Two peaks were observed at the temperatures 507 and 512 K. Wide angle X-ray patterns indicate that these are due to helical and planar zig-zag conformations of the PPL chains. After melting and recrystallizing these samples, melting peaks at 495 and 507 K were observed. They correspond to two different crystalline modifications of PPL. By changing the crystallization and annealing conditions, each of the two modifications can be isolated or prepared in various proportions.
    Notes: Des fibres orientées de polypivalolactone (PPL) ont été fondues dans un calorimètre enthalpique différentiel (DSC). Deux pics sont alors obtenus à des températures de 507 et 512 K. Ils correspondent à des phases formées de chaǐnes hélicoïdales et zig-zag planaires respectivement, tel que démontré par la méthode des rayons-X. Après la fonte et la recristallisation des ces měmes échantillons, deux pics de fusion sont révélés à des températures de 495 et 507 K. Ils correspondent à deux modifications cristallines différentes du PPL. Suivant les conditions de cristallisation et de recuit, chacune de ces deux modifications peut ětre isolée, ou un mélange des deux peut co-exister.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 2039-2051 
    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: In the history of the automobile, organic fibers have dominated the tire reinforcement field, starting with cotton and progressing through a series of man-made fibers, each finding its place on the basis of its special attributes and overall performance. In general, these fibers were engineered for textile applications, but were subsequently adapted by special processing to make them as suitable for tires as possible. However, each has had limitations which have kept it from certain segments of the market. Moreover, the performance demands on tires have become progressively more stringent, and new tire designs have evolved, so that new tire reinforcement materials are needed. While glass and steel wire are contributing some of the desired properties, they also have their limitations. On the other hand, the potential for creating new, more favorable property balances from organic fibers is far from exhausted. This paper will discuss the main tire yarn property criteria and the polymer and fiber structural factors which control them. Then, the properties and performance of an entirely new fiber, specifically engineered chemically and physically for tire reinforcement, will be described. Fiber properties discussed will include tensile strength, modulus, dimensional stability, fatigue resistance, adhesion, and thermal stability.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 107-112 
    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: ABA-type “tapered” block polymers were prepared from styrene (monomer A) and butadiene or isoprene, using an initiator of sec-butyllithium complexed with two molecules of ethyl ether. The stress-strain curves of polymers containing about 20-50% styrene show the usual resemblance to curves of crosslinked elastomers. The SBS polymers had higher tensile strengths than the SIS polymers. They also had slightly higher tensile strengths than comparable SBS polymers made with sec-butyllithium. The SIS polymers, however, had generally lower tensile strengths than those made with sec-butyllithium. This is probably caused by higher styrene content of the isoprene block, brought about by increased randomization of the styrene-isoprene copolymerization due to the presence of the ether. The A and B blocks become more compatible, producing loss of strength in the polymer. Infrared analyses of polydienes made with the sec-C4H9Li·2(C2H5)2O initiator showed a 6% to 8% increase in 1,2-content (for polybutadiene) or 3,4-content (for polyisoprene), compared to polymers made with sec-butyllithium. The polymer microstructures still have high (〉80%) total 1,4-content, however. Thus, this amount of ether can be tolerated in the polymerization system without great loss of rubbery properties or block structure in the resultant polymers.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 16 (1972), S. 163-173 
    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: ABA-type block polymers of styrene (monomer A) and isoprene or butadiene were prepared using two commercially available dilithium adducts of isoprene as initiators. One (DiLi-1) was predominantly dilithio diisoprene and contained a small amount of dimethyl ether (ether/Li 〉 1.0). The second (DiLi-1 C.E.) was a higher molecular weight version of DiLi-1, containing about seven isoprene units per molecule. It contained only a trace of dimethyl ether (ether/Li 〈 0.1). Polymers were made by charging all of the monomers at the start of the reaction. The diene polymerized first, incorporating some styrene. When the diene was consumed, the difunctional polymer chains then added a block of nearly pure polystyrene at each end. Thus an ABA-type polymer was synthesized in one step. These polymers show the usual behavior of pseudo-vulcanized elastomers. Their stress-strain curves are given. The SBS polymers had the higher tensile strengths. None had tensile strengths as high as SBS or SIS polymers made with n- or sec-butyllithium. It was shown that the diene blocks contain appreciable amounts of styrene. This leads to more compatibility between the A and B blocks; it also shortens the styrene blocks compared to the theoretical lengths of “pure” blocks. Both effects can lead to loss of tensile strength. Microstructures of the diene homopolymers made with these initiators are also given.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Thromboresistance of the alloy most often used in artificial heart valves depends upon a hitherto unrecognized erosion resistant hydrocarbon coating. Contact angle measurements show the actual surface to be dominated by closely packed methyl groups as occur with adlineated aliphatic chains. The likely source for this layer is a tallow-based compound from which adventitious components become tightly bound at the metal/air interface during final polishing. Here, as in other systems, the exposure of CH3 terminal groups correlates with significant blood compatibility.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 6 (1972), S. 305-325 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The central theme of this paper revolves about an attempt to provide information and ideas that might be useful to persons interested in cryogenic dental procedures. However, a broad spectrum of thermal properties is also considered. For convenience a summary table is given for pertinent thermal and mechanical properties of dental materials. A point demonstrated is that observations which are of direct empirical utility to dentists often can be enhanced in value if viewed in terms of simple analytical models. For example, a tooth can be expected to be somewhere between a sphere and a long rod in its cooling or heating characteristics. The importance of the thermal diffusivity rather than thermal conductivity in transient phenomena is discussed. Some graphical techniques that circumvent mathematical difficulties are developed in detail. An isolated extracted tooth in contact with a coolant approaches to within 98% of its final temperature in less than 1 min but in the jaw, in contact with a cold (or hot) probe, the equilibration will take much longer. Thermally generated stresses, either due to differences in expansivities of the dentin and enamel or to large temperature gradients across a single component, can be quite large (comparable to the reported tensile strength, 9.3 MN/m2 for enamel) at cryogenic temperatures. Our observations and analysis make us believe that the reported strength of 9.3 MN/m2 is too low by at least an order of magnitude.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    New York, N.Y. : Wiley-Blackwell
    Journal of Supramolecular Structure 2 (1974), S. 629-645 
    ISSN: 0091-7419
    Keywords: Life Sciences ; Molecular Cell Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Concanavalin A (Con A) binding and Con A-mediated hemadsorption to LM cells were found to decrease significantly at both 5-7°C and 15-19°C. The higher of these critical temperatures responds to a change in state of the membrane lipids and can be increased or decreased in cells where the membrane phospholipids contain less or more double bonds, respectively. The lower critical temperature for Con A binding or Con A-mediated hemadsorption does not respond to these changes in membrane lipid composition. Though the amount of Con A bound to the cell surface is a determinant of Con A-mediated agglutinability, the major components of the decreases in Con A-mediated hemadsorption which occur at both these critical temperatures do not have their origin in the decreases in Con A binding which occur over these same temperature ranges - that is 5-7°C and 15-19°C.Con A-mediated hemadsorption measured at 22°C was dramatically inhibited when LM cells were first incubated at 7°C or less. Reversal of this inhibition required 20-30 min of subsequent incubation at 22°C, indicating that factors other than membrane lipid “fluidity” are determinants of agglutinability. LM cells treated with the microtubule-disrupting alkaloids colchicine, colcemid, or vinblastine at concentrations as low as 10-6 M were as much as fourfold more agglutinable with Con A. By contrast, lumicolchicine, an inactive derivative of colchicine, had a slight inhibitory effect on Con A-mediated hemadsorption. Colchicine, vinblastine, or lumicolchicine treatment of LM cells did not alter the quantitative binding of labeled lectin. The results suggest that membrane lipid “fluidity” and the cell cytoskeleton (microtubule/microfilament system) are important determinants of lectin interactions with cell surfaces. The results are interpreted in terms of a model of cell-cell and cell-lectin interactions which assigns a central role to the Con A receptor.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 12 (1974), S. 1955-1968 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A general method is described to take into account the multiple scattering effect in a small-angle light scattering from thin polymer films. It is seen that multiple scattering tends to make the scattering envelope more diffuse, reducing the intensity in the high intensity regions and increasing it in the low intensity regions. The method is applied here to a spherulitic system, but it is valid for any other system where the principal scattering is in the forward direction.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 1347-1355 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Dynamic light-scattering experiments were performed on an ethylene-methacrylic acid copolymer and its sodium salt. The in-phase ΔI′ and out-of-phase ΔI″ components of the light scattering were measured in a temperature range between 25 and 65°C for both samples. No transition is seen in this temperature interval for the acid, but a clear transition occurs around 40°C for the salt. This transition is associated with the softening point of the ionic domains present in the sample.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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