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  • 1
    Electronic Resource
    Electronic Resource
    Study of the conformation of polyelectrolytes in dilute solutions by elastic neutron scattering
    Amsterdam : Elsevier
    Chemical Physics Letters 28 (1974), S. 505-507 
    Details
    ISSN: 0009-2614
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0009-2614(74)80089-8
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  • 2
    Electronic Resource
    Electronic Resource
    Atopic asthma: differential activation phenotypes among memory T helper cells (2001)
    Oxford, UK : Blackwell Science, Ltd
    Clinical & experimental allergy 31 (2001), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background T cells have been implicated in the pathogenesis of atopic asthma. We have previously shown that memory T helper cells (CD4+CD45RO+) are preferentially activated relative to naïve T helper cells (CD4+CD45RA+) after bronchial allergen challenge. However, specific T helper subpopulations that are activated in atopy and/or asthma remain undefined.Objective To determine the T helper subpopulations and activation phenotypes relevant to acute and stable asthma that may be common with or distinct from atopy.Methods Two groups of atopic asthmatics (ten acute and nine stable asthmatics) and two non-asthmatic groups (14 non-asthmatic atopics and eight normal non-atopic controls) were analysed. Ten acute asthmatics were assessed in the emergency room during an acute episode (FEV1 43.6% ± 18.4). Nine stable asthmatics were assessed during a symptom-free period (FEV1 85% ± 6). Using multiple colour flow cytometry we analysed T cell subpopulations and the expression of IL-2-receptor (IL-2R) and MHC-class II antigens (MHC II) on naïve and memory T helper cells in the peripheral blood of asthmatic and non-asthmatic groups.Results Atopic asthmatics (acute and stable) had an increased percentage of memory T helper cells expressing IL-2R compared with normal non-atopics (mean SD 16.1 ± 6%, 12.4 ± 2% and 7.7 ± 1.8%, P 〈 0.05) but not compared with non-asthmatic atopics (10 ± 3.5%). Naïve T helper cells had low expression of IL-2R and MHC II in all four groups. MHC II antigen expression was increased in memory T helper cells of asthmatics (acute and stable) compared with normal non-atopics (13.9 ± 7.5, 10.6 ± 5 and 4.9 ± 2.5, P 〈 0.05) but not compared with non-asthmatic atopics (7.92 4). A novel finding was that IL-2R and the MHC II molecules were mainly expressed in non-overlapping populations and coexpression was found predominantly on memory T helper cells. Asthmatics (acute and stable) had higher proportion of double positive memory T helper cells (IL-2R+MHC II+) compared with both non-asthmatic groups (P 〈 0.05).Conclusions We demonstrate a differential expression of IL-2R+ and MCH II+ on CD45RO+ T helper cells that would suggest that there are three subsets of activated memory T helper cells in asthmatics. Two non-overlapping IL-2R+ or MHC II+ CD45RO+ T helper cells and a third subpopulation of activated cells that coexpress IL-2R and MHC II (double positives). This latter subpopulation is significantly higher in asthmatics (acute or stable) compared with both non-asthmatic groups, suggesting a specific T helper activation phenotype distinct to atopic asthmatics as compared with atopic non-asthmatics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2222.2001.01146.x
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  • 3
    Electronic Resource
    Electronic Resource
    Organization in semi-dilute polyelectrolyte solutions observed by small-angle neutron scattering (1978)
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 11 (1978), S. 519-523 
    Details
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The study of semi-dilute polyelectrolyte solutions by small-angle neutron scattering shows that the correlation function S(q) of all the chains presents a peak for a value q = qh of the scattering vector q. This is taken as evidence for some organization among the elongated polyions. This phenomenon has been observed for a fraction of polymethacrylic acid of very low molecular weight. The experiments show essentially: (1) the progressive vanishing of the peak with the addition of a neutral salt at constant polyelectrolyte concentration; (2) the variation of qh with the polyelectrolyte concentration c, qh ∝ c1/2; (3) the decrease of the peak intensity as the charge density of the chain increases. These results, which indicate the important role of the electrostatic interactions on this organization phenomenon, are discussed in terms of a lattice model and a recently proposed isotropic model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0021889878013783
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  • 4
    Electronic Resource
    Electronic Resource
    Lateral migrations of solid spheres in tube flow (1991)
    Springer
    Rheologica acta 30 (1991), S. 131-139 
    Details
    ISSN: 1435-1528
    Keywords: Poiseuille flow ; Fokker-Planck equation ; pair collisions ; lateral particle migration ; suspension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Cross-flow displacements of neutrally buoyant solid spheres under Poiseuille-type flow conditions in narrow channels, at low volume fraction, are described by a phenomenological model within the framework of the Fokker-Planck equation. In this model, the effects of particle-particle and particle-wall interactions are taken into account. In addition to the classical wall effect (depleted layer near the wall), numerical solutions of the derived equations display two opposite lateral migrations towards the wall and the tube axis, and an alignment of the particles in adjacent layers parallel to the flow. These numerical results are then compared with experimental results obtained by Goldsmith and Marlow [18] for erythrocyte suspensions. A good qualitative agreement is observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01134602
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  • 5
    Electronic Resource
    Electronic Resource
    Viskosimetrische Untersuchung von Polyelektrolytlösungen durch isoionische Verdünnung. Einfluß der Ladungsdichte auf die Konformation des Polyions (1977)
    Springer
    Colloid & polymer science 255 (1977), S. 98-98 
    Details
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01449712
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  • 6
    Electronic Resource
    Electronic Resource
    Wall effects in the flow of flexible polymer solutions through small pores (1989)
    Springer
    Rheologica acta 28 (1989), S. 520-526 
    Details
    ISSN: 1435-1528
    Keywords: Polymersolution ; porous medium ; effectiveviscosity ; depletion layer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract Effective viscosities of dilute and semidilute flexible solutions flowing through small cylindrical pores were determined in the Newtonian regime for various pore diameters. The low viscosities relative to the bulk were associated with a depletion phenomenon due to a steric exclusion of macromolecules from the pore wall. Using a two-fluid flow model, the depletion layer thickness was determined and discussed as a function of polymer concentration, ionic strength, and molecular weight. This thickness, which was constant and close to the macromolecule gyration radius in dilute regime, was found to decrease rapidly with polymer concentration in the semidilute regime.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01332923
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  • 7
    Electronic Resource
    Electronic Resource
    Polyelectrolyte solutions: Intrachain and interchain correlations observed by SANS (1979)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Letters Edition 17 (1979), S. 379-384 
    Details
    ISSN: 0360-6384
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1979.130170608
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