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  • 21
    Electronic Resource
    Electronic Resource
    Kinetics of nucleic acid-large ligand interactions: Exact Monte Carlo treatment and limitingl cases of reversible binding (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2037-2050 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Many ligands, including basic polypeptides, histones, and other proteins bind nonspecifically to DNA in such a way as to render unavailable for further binding several contiguous sites (generally bases or base pairs). An accurate description of the kinetics of such large ligand binding requires a more complex theoretical analysis than does the study of the binding of small ligands to DNA. An exact analytical solution of the problem does not appear feasible. Instead, a Monte Carlo approach is developed which provides an essentially exact numerical solution by simulating the binding experiment using a model one-dimensional lattice to represent the DNA molecule. For the limiting cases of totally irreversible binding and of instantaneous redistribution of bound ligands along the lattice, relatively simple equations can be written and solved for the binding kinetics. These solutions and their realms of applicability are discussed in some detail.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180815
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  • 22
    Electronic Resource
    Electronic Resource
    Kinetics of cooperative ligand-lattice binding: Fast Monte Carlo integration (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 543-547 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A fast Monte Carlo integration algorithm with varying time step is described for cooperative binding of ligands of arbitrary length to a one-dimensional lattice. This algorithm is particularly suitable for strongly cooperative or anticooperative systems, i.e., when the time scales for different kinetic events are very different. As an application, the kinetics of a bimodal two-ligand system are briefly discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360290309
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  • 23
    Electronic Resource
    Electronic Resource
    The irreversible binding of 2-site ligands to hetereogeneous polymers (1990)
    New York : Wiley-Blackwell
    Biopolymers 29 (1990), S. 1331-1349 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We obtain an analytical solution for the binding of 2-site ligands to a heterogeneous lattice. The model also describes the kinetics of chemical reactions between adjacent pendant groups of a copolymer. Our analysis is based on the principle of independence, as formulated by Gonzalez and Hemmer. Several special cases are solved in closed form; a power series solution is developed for the general problem. The results may be modified to take into account fixed total ligand. We also analyze competition between 1-site and 2-site ligands. As an illustration of the results, we examine in detail the kinetics and final extent of binding for two special cases.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360291002
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  • 24
    Electronic Resource
    Electronic Resource
    Studies on interaction between poly(L-lysine) and DNA of varied G + C contents (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2401-2415 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Interaction between polylysine and DNA's of varied G + C contents was studied using thermal denaturation and circular dichroism (CD). For each complex there is one melting band at a lower temperature tm, corresponding to the helix-coil transition of free base pairs, and another band at a higher temperature t′m, corresponding to the transition of polylysine-bound base pairs. For free base pairs, with natural DNA's and poly(dA-dT) a linear relation is observed between the tm and the G + C content of the particular DNA used. This is not true with poly(dG)·poly(dC), which has a tm about 20°C lower than the extrapolated value for DNA of 100% G + C. For polylysine-bound base pairs, a linear relation is also observed between the t′m and the G + C content of natural DNA's but neither poly(dA-dT) nor poly(dG)·poly(dC) complexes follow this relationship. The dependence of melting temperature on composition, expressed as dtm/dXG·C, where XG·C is the fraction of G·C pairs, is 60°C for free base pairs and only 21°C for polylysine-bound base pairs. This reduction in compositional dependence of Tm is similar to that observed for pure DNA in high ionic strength. Although the t′m of polylysine-poly(dA-dT) is 9°C lower than the extrapolated value for 0% G + C in EDTA buffer, it is independent of ionic strength in the medium and is equal to the tm0 extrapolated from the linear plot of tm against log Na+. There is also a noticeable similarity in the CD spectra of polylysine· and polyarginine·DNA complexes, except for complexes with poly(dA-dT). The calculated CD spectrum of polylysine-bound poly(dA-dT) is substantially different from that of polyarginine-bound poly(dA-dT).
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360141113
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  • 25
    Electronic Resource
    Electronic Resource
    Kinetics of large-ligand binding to one-dimensional lattices: theory of irreversible binding (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 765-788 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Exact solutions are obtained for the time dependence of the extent of irreversible binding of ligands that cover more than one lattice site to a homogeneous one-dimensional lattice. The binding may be cooperative or noncooperative and the lattice either finite or infinite. Although the form of the solution is most convenient when the ligand concentration is buffered, exact numerical or approximate analytical solutions, including upper and lower bounds, can be derived for the case of variable ligand concentration as well. The physical reason behind the relative simplicity of the kinetics of irreversible as opposed to reversible binding in such systems is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180404
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  • 26
    Electronic Resource
    Electronic Resource
    Kinetics of nucleic acid-large ligand interactions: Multiplet-closure approximations and matrix-iteration techniques (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1651-1669 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Approximate methods are developed and evaluated for treating the rate of binding ligands that cover several contiguous sites to a homogeneous one-dimensional lattice, which represents a nucleic acid or other linear biopolymer. The model requires as input only the number of lattice sites necessary for binding, the total number (possibly infinite) of lattice sites, and elementary rate constants for the cooperative and noncooperative association and dissociation of the ligand on the lattice. The computational methods employed are an extension of the triplet closure approximation from the helix-coil (single-site ligand) problem to the large ligand binding problem. It is found that consideration of clusters of n + 2 lattice sites, where each ligand covers n sites, gives a surprisingly accurate description of the kinetics. The approximation is implemented by an extension of the matrix-iteration approach proposed by Craig and Crothers. The effects of the finite lattice length, as well as the capability to treat ligand motion along the lattice, are incorporated. When all symmetries are taken into consideration, the time required for the matrix iteration calculation rises only linearly with the ligand length n and is considerably less than that of the Monte Carlo method, which is used as a standard for comparison.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200808
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  • 27
    Electronic Resource
    Electronic Resource
    Studies related to in-plane flow behavior of elastomer matrix in nonwoven fibrous structures (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 51 (1994), S. 1629-1646 
    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 purpose of the present work has been to produce knowledge as regards the rheological behavior of polymer matrix in nonwoven fibrous reinforcing structures for composites. The results are expected to contribute toward a better understanding of flow mechanisms in fibrous systems in order to develop better techniques for fabricating elastomer-based composites. Theoretical and experimental analyses have been made of interactions between the structural parameters of the fibrous mats and the flow characteristics of the matrix with systematically varied material and process parameters. In nonwoven mats with fibers laid lengthwise, the flow rate along the fiber direction was found to be significantly higher than the flow rate crosswise to the fiber direction. Nonwoven mats with multidirectionally laid fibers exhibited a practically radial flow front pattern. Nonwoven mats made of coarser fibers showed greater matrix polymer flow rate as compared with finer fibers. The matrix flow distance was proportional to the logarithm of injection time. The decrease of pressure in the mold cavity was linearly proportional to the matrix flow distance. The dependence of permeability on the level of compression of the fibrous structure is in agreement with the results published by other workers. © 1994 John Wiley & Sons, Inc.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1994.070510913
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  • 28
    Electronic Resource
    Electronic Resource
    Studies of the effect of fiber surface and matrix rheological properties on nonwoven reinforced elastomer composites (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 57 (1995), S. 751-765 
    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 influence of fiber type and fiber-surface properties on matrix flow behavior was investigated using structural reaction injection-molding (SRIM). The influence of fiber type, fiber-surface properties, and matrix type on strength properties in elastomeric composites reinforced with nonwoven fibrous structures was investigated using tensile tests on elastomer composite samples from SRIM and latex coagulation (LC) fabrication methods and the microbond strength method on individual fibers. The fibers used were PET, LLDPE, and p-aramid. Fibers were treated with epoxy, styrene, and isocyanate derivatives, which make the surface chemically reactive. Treatments were also made with NaOH and a copolymer of polyester and polyol ether, causing a change in the fiber surface energy. The matrix types were polyurethane elastomer and natural rubber. The results show that the surface treatments which produced a change in the surface energy influenced the flow rate of the matrix polymer during the composite fabrication process. The treatments resulted in chemically reactive fiber surfaces which improved the fiber-matrix bond strength without affecting the Young's modulus of the composite material. Good correlation was found between bond strength and surface energy including the dispersive component of surface energy in the case of polyurethane elastomer and surface-modified PET fibers. The age of the polyurethane matrix has a marked influence on the bond strength. The fiber volume fraction in composites has a strong influence on the Young's modulus of the elastomer composite. © 1995 John Wiley & Sons, Inc.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070570610
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  • 29
    Electronic Resource
    Electronic Resource
    Reinforcement factors in fibers from block copolyamides and polyamide blends (1973)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 17 (1973), S. 849-861 
    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 modulus of a fiber can be increased by plying with it a higher-modulus fiber. In this case, the modulus of the combination is characterized by a springs-in-parallel model, and the modulus of the composite is a linear function of the per cent of the second fiber in the composite. Another method of obtaining reinforcement is to melt-blend a higher-modulus polymer with the substrate polymer. With polyamides, this leads to a certain degree of amide interchange and block copolymer formation which depends on the compatibility of the polymers as well as on the usual kinetic factors. If the dispersion of the higher-modulus polymer is such that aggregate size is relatively large (e.g., ≥500 Å) and if the adhesion between the two polymers is good, a springs-in-parallel-type reinforcement is the best which can be obtained. In melt-blend polyamides, a “nonclassical” phenomenon in reinforcement has been noted when the diameters of the dispersed aggregates are ≤500 Å and when there are a relatively high number of hydrogen bonding sites on both polymer components. In this case, it appears that moduli appreciably higher than predicted from a springs-in-parallel model are obtained as well as higher than expected Tg values. A mechanism is proposed to account for this “nonclassical” behavior along with data to support it. Another type of anomaly is observed when the components of the blend are isomorphous. In this case, the reinforcement is considerably less than expected.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1973.070170315
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  • 30
    Electronic Resource
    Electronic Resource
    Copolymers in dilute solution. I. Preliminary results for styrene-methyl methacrylateWork supported in part by Office of Ordnance Research. (1996)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 34 (1996), S. 1005-1018 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The dilute solution properties of copolymers are briefly discussed in relation to those of the parent homopolymers. It is shown that copolymer molecules are usually more expanded in solution than would be expected from the averaged behavior of the pure polymers, because of repulsive interactions between the unlike monomer units. A thermodynamic parameter χAB characterizing these interactions can be derived from measurements of the dilute solution properties of copolymers. In favorable cases this parameter can be independently evaluated from studies of ternary systems composed of the two parent homopolymers and a solvent, thus allowing prediction of the behavior of the copolymer. Light scattering and viscosity measurements on fractions of approximately equimolal copolymers of styrene and methyl methacrylate are presented and analyzed. The values of χAB deduced from the results in two solvents agree satisfactorily with each other, but are somewhat larger than those earlier obtained from measurements on ternary systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1996.905
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