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  • 1
    Electronic Resource
    Electronic Resource
    Expression of CD69 on T-cells from HIV-1-infected children and adolescents increases with increasing viral load (1999)
    Springer
    European journal of pediatrics 158 (1999), S. 638-644 
    Details
    ISSN: 1432-1076
    Keywords: Key words HIV-1 ; T-cells ; CD69 ; Activation ; Children
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We evaluated the use of a whole-blood assay that measures spontaneous and activation-induced CD69 expression on peripheral blood T-cells in vitro for assessment of T-cell function in HIV-1-infected paediatric patients. Heparinized venous blood from 28 HIV-1 positive children and adolescents and 23 healthy controls was incubated for 4 h with or without 5 μg/ml phytohaemagglutinin (PHA). Thereafter, analysis of CD69 expression on CD4+ and CD8+ T-cells was done by flow cytometry; simultaneously we determined CD4+ T-cell counts and plasma HIV-1 viral load. Neither spontaneous nor PHA-induced CD69 expression differed significantly between HIV-1 positive patients and healthy controls. However, T-cells from HIV-1 positive patients with plasma HIV-1 viral load levels above 70 × 103 copies/ml showed a higher spontaneous CD69 expression than T-cells from patients with lower plasma viral load levels in different stages of the disease. Antiretroviral treatment in four patients reduced spontaneous CD69 expression in CD4+ T-cells and PHA-induced CD69 expression in CD4+ and CD8+ T-cells significantly after 8 weeks of therapy. Conclusion Spontaneous and activation-induced expression of the early (activation) antigen CD69 on peripheral blood T-cells does not distinguish HIV-1 positive patients from HIV-1 negative healthy controls and is not correlated with peripheral blood CD4+ T-cell counts. This test may not be a reliable marker for functional T-cell deficiency during early stages of HIV disease. Increased spontaneous as well as PHA-induced CD69 expression on T-cells from HIV-1-infected children and adolescents in vitro may rather reflect HIV-induced pre-activation of T-cells in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004310051167
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  • 2
    Electronic Resource
    Electronic Resource
    Weld lines in injection moulded polypropylene parts. Mechanical properties morphology relationships (1990)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 179 (1990), S. 35-56 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Morphologie von Polypropylen-Spritzgußteilen mit Bindenaht wurde mit Röntgenweit-und Kleinwinkelstreuung, Lichtstreuung und Polarisationsmikroskopie untersucht. Die erhaltenen morphologischen Daten wurden mit mechanischen Werten aus Zugversuchen korreliert. Es wird gefunden, daß die mechanischen Eigenschaften der untersuchten Proben im wesentlichen von der sphärolithstruktur beeinflußt werden. Anhäufungen von Sphärolithen mit Kristallen der hexagonalen β-Modifikation und eine starke Inhomogenität der Sphärolithstruktur senkrecht zur Bindenaht sind der wesentliche Grund für die verschlechterten mechanischen Eigenschaften. Diese Sphärolithstruktur wird durch die Temperatur des Spritzgußwerkzeugs stark beeinflußt. Die Lamellen-Überstruktur hat dagegen einen vernachlässigbar kleinen Einfluß auf das mechanische Verhalten.
    Notes: The morphology of polypropylene plaques containing a weld line, has been investigated by x-ray wide and small angle scattering, light scattering and polarization microscopy. The results are correlated to mechanical values obtained from tensile tests. While the lamellar morphology is of neglectable influence, it is found, that the mechanical properties of the samples are strongly influenced by the spherulitic structure. Clustering of β-type spherulites and strong morphological inhomogeneities in the vicinity of the weld line are the primary reason for the mechanical weakening of the plaques. The temperature of the mould has a strong effect on the spherulitic structure and thus on the tensile properties of the samples.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1990.051790104
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  • 3
    Electronic Resource
    Electronic Resource
    Zusammenhänge zwischen mechanischem Verhalten und Morphologie von eigenfaserverstärkten Poly(propylen)/Poly(1-buten)-Blends, kristallisiert aus der hochorientierten Schmelze (1991)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 192 (1991), S. 183-197 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The tensile properties of self reinforced poly(propylene)/poly(1-butene) composites, obtained by rapid extension of the melt, have been measured and correlated to morphological parameters derived from x-ray experiments. Critical fiber lengths as a function of sample composition and the elastic modulus and yield stress of the fibers could be determined. It is shown, that, applying a load to the system, the forces are fully taken up by the fibers and the system breaks by fail of the fibers. The longitudinal structure of the fibers is found to be independent of sample composition.
    Notes: Mechanische Parameter wie Elastizitätsmodul, Fliß- und Bruchspannung von aus der hochorientierten Schmelze hergestellten nadelkristallinen Mischungen aus Poly(propylen) und Poly(1-bute) wurden mit morphologischen Parametern, die aus Röntgenmessungen abgeleitet wurden, korreliert. Es wird gezeigt, daß der Elastizitätsmodul des Verbundes aus den E-Moduln der Fasern und der Matrix berechnet werden kann (Mischungsregel). Die an der Probe angreifenden Kräfte werden voll auf die Fasern übertragen; der Verbund kann daher als eigenfaserverstärktes System angesehen werden. Die Abschätzung der kritischen Faserlänge ergibt, daß die Festigkeit der FAsern voll ausgenutzt wird; der Bruch des Systems bei Belastung ist daher auf das Versagen der Fasern zurückzuführen. Das mechanische Verhalten des Verbundes wird stark beeinflußt durch die Komponentenzusammensetzung. Die longitudinale Struktur der Nadeln beider Komponenten bleibt unbeeinflußt von der jeweiligen Co-Komponente.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1991.051920115
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  • 4
    Electronic Resource
    Electronic Resource
    Interface distribution functions of diluted polymer systems containing core fibrils (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 157 (1988), S. 165-176 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus der Röntgenkleinwinkelstreuung von aus der orientierten Schmelze kristallisierten Legierungen aus isotaktischem Polypropylen und Poly(1-buten) wurden Grenzflächenverteilungsfunktionen berechnet. Die Proben enthalten Nadelkristalle, die in Bezug auf ihre Abstandsverteilung ein „verdünntes System“ darstellen. Es wird gezeigt, daß die Berechnung von Grenzflächenverteilungsfunktionen aus jeweils nur zwei Grenzflächen möglich ist. Der Vergleich der erhaltenen Nadeldicken mit Ergebnissen aus anderen Auswertemethoden ergibt eine gute Übereinstimmung.
    Notes: Interface distribution functions have been evaluated from the equatorial small angle x-ray scattering of blends of isotactic polypropylene and poly(1-butene) crystallized in the shear field of the oriented melt. The samples contain core fibrils which represent a diluted system with respect to their distance statistics. It is shown, that interface distribution functions can be calculated from only two interfaces (diffuse phase boundaries between fibrils and amourphous phase). The calculated thicknesses agree well with values determined from other methods.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051570113
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  • 5
    Electronic Resource
    Electronic Resource
    Dispersion of trans-polyoctenylene in isotactic poly(propylene), 2Part 1: cf.(1).. Crystallization behaviour (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 191-199 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystallization kinetics of thin films of isotactic poly(propylene) (iPP) and transpolyoctenylene rubber (TOR) was investigated by optical microscopy. Nucleation densities, Avrami exponents and spherulitic growth rates show specific dependencies on the concentration of TOR in the blend. From the results it is concluded, that at a mass fraction of TOR wTOR = 0,10 the TOR is more finely dispersed in the blend than for other compositions. Due to the subsequent formation of interfaces, the nucleation is found to be predominantly heterogeneous at wTOR = 0,10, while it is preferentially homogeneous at all other compositions.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920201
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  • 6
    Electronic Resource
    Electronic Resource
    Dispersion of trans-polyoctenylene in isotactic poly(propylene), 1. Morphology/mechanical properties relationships (1991)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 192 (1991), S. 85-99 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Blends of isotactic poly(propylene) (iPP) and trans-polyoctenylene (TOR), prepared from solution, exhibit unexpected mechanical properties at specific mass fractions of TOR: While generally the elastic modulus E decreases continuously with increasing TOR content, it surpasses a maximum for mass fractions of TOR around 0,10. The reason for this behaviour is investigated. It turns out that the crystallinity as well as the crystal morphology (which is investigated by evaluating small-angle X-ray scattering by interface distribution functions) does not explain the mechanical behaviour. The order of the lamellar stacks (number of orientation-correlated crystals) proves to be well correlated with the course of the elastic modulus. This order is a consequence of the increasing dispersion of TOR at mass fractions between 0,075 and 0,20 creating interfaces and infecting subsequently the crystallization conditions in the sample.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1991.021920108
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  • 7
    Electronic Resource
    Electronic Resource
    The influence of rubber-matrix interfaces on the crystallization kinetics of isotactic polypropylene blended with ethylene-propylene-diene terpolymer (EPDM) (1993)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 33 (1993), S. 877-888 
    Details
    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: Blends of isotactic polypropylene with amorphous and slightly crystalline ethylene-propylene-diene terpolymer (EPDM), prepared by solution blending, have been investigated by optical microscopy and differential scanning calorimetry. Nucleation and crystallization kinetic parameters, such as nucleation rates, nucleation half times, Avrami-exponents and spherulitic growth rates, have been determined. It has been found that the dispersion of crystalline EPDM in iPP is different from that of amorphous EPDM. Both EPDMs are incorporated into the spherulites, causing a decrease of the maximum growth rate of the iPP spherulites. The surface free energy of the iPP crystals is diminished on adding EPDM to iPP and is accompanied by a higher secondary nucleation rate. From the decrease observed in the Avrami exponent with increasing EPDM concentration in the blend, it has been concluded that nucleation becomes predominantly heterogeneous, as there is a proportional increase in the interfacial area between the two components.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760331403
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  • 8
    Electronic Resource
    Electronic Resource
    Kurzmitteilung zum Mechanismus der Spannungsübertragung in eigenfaserverstärkten Kunststoffen (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 163 (1988), S. 199-204 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Mechanical parameters like Youngs modulus and yield stress have been measured from a set of samples of fiber reinforced polymer composites. The values have been correlated to the lateral diffuse phase boundary thicknesses of the fibers. It has been found, that the phase boundary is an important morphological feature responsible for the transfer of load from the matrix onto the fibers.
    Notes: An aus der orientierten Schmelze kristallisierten, eigenfaserverstärkten Polymerlegierungen aus isotaktischem Polypropylen (iPP) und isotaktischem Poly(1-buten) (PB-1) wurden mechanische Parameter (E-Modul, Fließspannung) gemessen und mit aus äquatorialen Röntgenkleinwinkelstreukurven bestimmten lateralen Grenzschichtdicken korreliert. Die Kurvenverläufe von E-Modul, Fließspannung und Grenzschichtdicke als Funktion der Komponentenzusammensetzung stimmen qualitativ überein. Es wird gezeigt, daß die Morphologie der Grenzschicht von besonderer Bedeutung für die Übertragung der Spannungen von der Matrix auf die Fasern ist.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051630117
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  • 9
    Electronic Resource
    Electronic Resource
    Lokale mischbarkeit von isotaktischem polypropylen (iPP) und trans-polyoctenylen (TOR) in grenzschichten von iPP/TOR-blends (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 200 (1992), S. 109-123 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Blends of isotactic polypropylene (iPP) and trans-polyoctenylene (TOR) were studied by differential scanning calorimetry (DSC), wide-angle and small-angel X-ray scattering, torsion pendulum analysis and polarization microscopy (nucleus formation and crystallization kinetics). Melting and crystallization temperatures and the superstructure as well are only slightly influenced by the blend composition. The glass transition temperatures determined by loss modulus measurements show interesting dependences. The obliquity of G″-(T)-maxima was calculated and exhibits that iPP-molecules diffuse into the TOR-matrix and  -  to a smaller extent  -  vice versa. Thus, a boundary layer volume is formed with both components locally mixed, which is responsible for the higher portion of heterogeneous nucleus formation.
    Notes: Blends aus isotaktischem Polypropylen (iPP) and trans-Polyoctenylen (TOR) wurden mit Differentialkalorimetrie, Röntgenweit- und -kleinwinkelstreuung, Torsionsschwingungsanalyse und Polarisationsmikroskopie (Keimbildung und Kristallisationskinetik) untersucht. Schmelz- und Kristallisationstemperaturen ändern sich nur wenig als Funktion der Komponentenzusammensetzung; auch die Überstruktur ist nahezu invariant gegenüber der Konzentration des zugemischten TOR. Die aus den Verlustmodulmaxima der Torsionsschwingungskurven bestimmten Glastemperaturen zeigen jedoch interessante Abhängigkeiten. Durch Berechnung der Schiefe der G″-(T)-Maxima wird gezeigt, daß iPP-Moleküle in die TOR-Komponente diffundieren, in geringerem Maße auch TOR-Moleküle in die iPP-Matrix. Dadurch bildet sich ein Grenzschichtvolumen, in dem beide Komponenten lokal gemischt sind. Dieses Grenzschichtvolumen ist verantwortlich für den gemessenen erhöhten Anteil der heterogenen Keimbildung.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.052000109
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  • 10
    Electronic Resource
    Electronic Resource
    Determination of avrami-exponents of isotactic polypropylene by means of X-ray methods (1993)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 211 (1993), S. 205-212 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Avrami-Exponenten von Polypropylen wurden nach zwei Methoden ermittelt: durch die Beobachtung des Sphärolithwachstums im Polarisationsmikroskop und durch die Bestimmung der Kristallinität als Funktion der Kristallisationszeit mittels Röntgenweitwinkelstreuung. Beide Methoden ergaben die gleichen Werte, so daß sich die Bestimmung des Avrami-Exponenten durch optische Mikroskopie, trotz der Grenzen dieser Methode wegen des eingeschränkten Kristallisationsvolumens zwischen den Glasträgern, durch ausreichende Genauigkeit auszeichnet. Mit der Röntgenstreumethode kann der Avrami-Exponent der bei längeren Kristallisationszeiten auftretenden sekundären Kristallisation ermittelt werden. Es wird gezeigt, daß diese Kristallisation innerhalb der schon gebildeten Sphärolithe stattfindet, deren Grauoßenverteilung unverändert bleibt.
    Notes: Avrami-exponents of polypropylene have been measured using two methods: observing the spherulitic growth in the polarization microscope, and measuring the crystallinity as a function of crystallization time using X-ray wide angle scattering. Both methods yield the same values, showing that the determination of the Avrami-exponent with optical microscopy is of sufficient accuracy despite the limitations of this method imposed by the restricted crystallization volume between the glass slides. Using the X-ray method, the Avrami-exponent of the secondary crystallization volume between the glass slides. Using the X-ray method, the Avrami-exponent of the secondary crystallization occurring at longer crystallization times can be measured. It is shown that this type of crystallization takes place within the already existing spherulites, whose size distribution is not changed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1993.052110117
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