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  • 1
    Electronic Resource
    Electronic Resource
    Ion complexation in nonactin, monactin, and dinactin: A Raman spectroscopic study (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 157-185 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ability of the macrotetrolide nactins to complex selectivity with a wide variety of cations makes these ionophorous antibiotics important model systems for the study of biologic ionic transport. We report a Raman spectroscopic investigation of the Na+, K+, Rb+, Cs+, Tl+, NH4+, NH3OH+, C(NH2)3+, and Ba++ complexes of nonactin, monactin, and dinactin in 4:1 (v/v) CH3OH/CHCl3 and in the solid state. The nactins display characteristic spectral changes upon complexation, some of which are specific for a given cation. In the K+, Rb+, Cs+, NH3OH+, and C(NH2)3+ complexes, which are apparently isosteric, the ester carbonyl stretch frequency is found to be linearly proportional to the cation-carbonyl electrostatic interaction energy, as calculated from a simplified model. Deviations for the Na+, NH4+, Tl+, and Ba++ complexes are interpreted as arising from additional nonelectrostatic interactions. Additional information is obtained from other spectral regions and from measurements of depolarization ratios. Spectra of the nactin complexes differ from each other more in the solid state than in solution, reflecting the effects of crystalline contact forces.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160112
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  • 2
    Electronic Resource
    Electronic Resource
    Nonactin, monactin, dinactin, trinactin, and tetranactin. A Raman spectroscopic study (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 2311-2327 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Raman spectra are reported for crystalline nonactin, monactin, dinactin, trinactin, and tetranactin and their solutions in CCl4, CHCl3, CH3OH, and 4:1 (v/v) CH3OH:CHCl3. The macrotetrolide nactins selectively bind a wide variety of cations, and are important model compounds for the study of ion complexation. The conformations of nonactin, monactin, and dinactin in solution are similar. Their conformations are found to be sufficiently open to permit the ester carbonyl groups to form hydrogen bonds with CH3OH; this gives rise to characteristic changes in the vibration frequencies associated with the ester groups. Nonactin, which is the least soluble of the nactins in CH3OH, is also the least effective at forming hydrogen bonds with CH3OH. The greater ability of the higher nactins to form hydrogen bonds with CH3OH may be due to the increased inductive effect of ethyl over methyl side chains, which may increase the dipole moment of the ester carbonyl groups. Spectra of crystalline nonactin, monactin, and tetranactin are fairly similar, while the spectra of dinactin and trinactin comprise a second, distinct family. This is consistent with X-ray crystallographic studies, which show that nonactin and tetranactin form monoclinic crystals, while trinactin is triclinic.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360141107
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  • 3
    Electronic Resource
    Electronic Resource
    Fluorescence correlation spectroscopy and nonideal solutions (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 499-508 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The information that may be obtained from a fluorescence correlation spectroscopic study of a nonideal solution is considered. If all of the macromolecules in a two-component solution are fluorescently labeled, the mutual diffusion coefficient will be measured. If only a few of the macromolecules in a solution are fluorescently labeled, the tracer diffusion coefficient will be obtained. Two nonideal systems that probably may usefully be studied with fluorescence correlation spectroscopy are proposed. The application of fluorescence correlation spectroscopy to studies of lateral diffusion in biological membranes is discussed; the form of the contribution to the fluorescence correlation spectrum of bulk motion within a membrane is noted.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140306
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  • 4
    Electronic Resource
    Electronic Resource
    Temperature dependence of the diffusion coefficient of polystyrene latex spheres (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 593-595 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220203
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  • 5
    Electronic Resource
    Electronic Resource
    Diffusion of bovine serum albumin in a neutral polymer solution (1985)
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 379-386 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The diffusion coefficient D of bovine serum albumin through various solutions (pH 7.0, 0.5M NaCl) of polythylene oxide (Mw ∼ 1 × 105, 3 × 105) was studied with quasielastic light scattering. In solutions of the 1 × 105 polymer solution at polymer concentrations above 0.5 g/L, D is considerably greater than would have been expected from the viscosity of water:polymer mixtures, the deviations being larger at low protein concentration that at high protein concentration. With either polymer, D falls with increasing protein concentration.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360240206
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  • 6
    Electronic Resource
    Electronic Resource
    Higher order hydrodynamic interactions in the calculation of polymer transport properties (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 31 (1993), S. 1785-1797 
    Details
    ISSN: 0887-6266
    Keywords: diffusion ; hydrodynamics ; transport properties ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Higher order hydrodynamics interactions are short-range modifications to the Oseen tensor Tij and its self-interaction counterpart Tii. They differ from the Oseen tensor in having terms of higher order than the first in a/R, a being a bead radius and R being a bead-bead distance. Effects of higher order hydrodynamic interactions on whole chain-whole chain hydrodynamic interactions are here computed. Higher order hydrodynamic interactions are shown to lead to a concentration dependence of the diffusion and friction coefficients of a free monomer. However, while higher order interactions make contributions of the same nature to the drag coefficients of a monomer and of a whole chain, the contributions are not simply multiplicative, removing a justification for the common practice of correcting polymer solution transport data for “monomer friction effects” via a normalization with data on friction coefficients of free monomers. © 1993 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1993.090311212
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  • 7
    Electronic Resource
    Electronic Resource
    Relaxational mode structure for optical probe diffusion in high molecular weight hydroxypropylcellulose (1998)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 36 (1998), S. 3087-3100 
    Details
    ISSN: 0887-6266
    Keywords: polymer dynamics ; light scattering spectroscopy ; probe diffusion ; coupling model ; Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We studied translational diffusion of dilute monodisperse spheres (diameters 14 〈 d 〈 455 nm) in aqueous 1 MDa hydroxypropylcellulose (0 ≤ c ≤ 7 g/L) at 25°C using quasielastic light scattering. Spectra are highly bimodal. The two spectral modes (“slow,” “fast”) have different physical properties. Probe behavior differs between small (d 〈 Rh) and large (d ≥ Rg) probes; Rh and Rg are the matrix polymer hydrodynamic radius and the radius of gyration, respectively. We examined the dependences of spectral lineshape parameters on d, c, scattering vector q, and viscosity η for all four probe-size and mode-type combinations. We find three time scale-separated modes: (1) a large-probe slow mode has properties characteristic of particle motion in a viscous medium; (2) a large-probe fast mode and small-probe slow modes share the same time scale, and have properties characteristic of probe motion coupled to internal chain dynamics; and (3) a small-probe fast mode has properties that can be attributed to the probe sampling local chain relaxations. In the analysis, we also attempted to apply the coupling/scaling (CS) model of Ngai and Phillies [Ngai, K. L., Phillies, G. D. J. J. Chem. Phys., 105, 8385 (1996)] to analyze our data. We find that the second mode is described by the coupling/scaling model for probe diffusion; the first and third modes do not follow the predictions of this model. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 3087-3100, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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