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  • 1
    Electronic Resource
    Electronic Resource
    Influence of oxygen on the viscosity of Zr–Al–Cu–Ni metallic glasses in the undercooled liquid region (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 83 (1998), S. 3438-3440 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The viscosity of Zr–Al–Cu–Ni metallic glasses prepared as melt-spun ribbons, slowly cooled bulk samples, and mechanically alloyed powder exhibiting different oxygen contents was measured above the glass transition temperature Tg using parallel-plate rheometry. For rapidly quenched ribbons, oxygen contents ≤0.8 at. % do not drastically affect the viscosity of the glassy phase, but changes in the composition of the metallic constituents are more significant. For slowly cast samples, oxygen levels above 0.3 at. % lead to an increase in viscosity due to formation of crystalline phases. In contrast, mechanical alloying provides completely amorphous powders even for oxygen contents above 2 at. %. This allows measurement of the influence of oxygen on the viscosity of single-phase glassy alloys for high oxygen levels, revealing a significant increase in viscosity with increasing oxygen content. The viscosity in the undercooled liquid can be fitted well by a Vogel–Fulcher–Tammann (VFT) relation. Independent of their oxygen content, the samples exhibit a small VFT temperature T0 and a high melt viscosity which are characteristic of a strong glass. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.367114
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  • 2
    Electronic Resource
    Electronic Resource
    M cells in the rabbit palatine tonsil: the distribution, spatial arrangement and membrane subdomains as defined by confocal lectin histochemistry (1997)
    Springer
    Anatomy and embryology 195 (1997), S. 353-358 
    Details
    ISSN: 1432-0568
    Keywords: Key words M cell ; Tonsil ; Mucosa-associated lymphoid tissue ; Lectins ; Glycoconjugates ; Confocal laser scanning microscopy ; Rabbit
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The crypt epithelium of the palatine tonsil contains M cells that play an important role in the uptake of luminal antigens to initiate immune responses. To study the close interaction of M cells, squamous epithelial cells and lymphocytes we used confocal laser scanning microscopy and the lectin from Ulex europaeus (UEA-I), which selectively labels rabbit tonsillar M cells. Confocal serial sections and synthetic section planes showed that the M cells comprise up to 35% of the epithelial cells in the tonsil crypt and completely engulf clusters of two to eight lymphocytes with their apical cytoplasm. These lymphocytes lie in a pocket of the M cell’s basolateral membrane that invaginates from one of the lateral aspects and forms a tunnel-like opening. Therefore, the tonsillar M cells closely resemble the M cells of the small and large intestines in their spatial structure, and likewise maintain an intraepithelial compartment for the interaction of lymphocytes, macrophages and antigens. The UEA-I bound intensely to the apical membrane of the M cells and to transcytotic vesicles in the apical cytoplasm. The pocket membrane bound the UEA-I more avidly than the remaining basolateral membrane, suggesting that the basolateral membrane of M cells is subdivided into membrane domains with different compositions of glycoconjugates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050055
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  • 3
    Electronic Resource
    Electronic Resource
    Characteristics of Slowly Cooled Zr-Al-Cu-Ni Bulk Samples with Different Oxygen Content (1998)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 269-272 (Jan. 1998), p. 797-806 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/03/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.269-272.797.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    Use of a digital film scanner to enhance low-power bright field photomicrography (1998)
    Springer
    Anatomy and embryology 198 (1998), S. 435-438 
    Details
    ISSN: 1432-0568
    Keywords: Key words Microscopy ; Digital film scanner ; Image processing ; Bright field ; Multimedia ; Medical education
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Low-power bright field photomicrographs often suffer from insufficient sharpness, uneven illumination, and colour hues. Using a film scanner, commercially available and designed for digitizing 35-mm transparencies, we directly scanned microscopic slides that carried dye-labelled and stained sections. The digital images covered a field of up to 24×36 mm and revealed excellent sharpness, absolutely even illumination and superior colour reproduction as compared to conventional photomicrographs taken with binoculars, macro lenses, or microscopes. As the method requires neither specialized instrumentation nor expert knowledge of photomicrographic techniques, it reduces costs and saves time. The high-quality digital survey micrographs can easily be used for image processing, image analysis and morphometry. Thus, this new method is valuable not only for pathology, embryology, histochemistry, and the neurosciences, but also for the exchange of low-power micrographs via the internet and for computer media that are increasingly used in medical education.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050194
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  • 5
    Electronic Resource
    Electronic Resource
    Expression of fucose residues in entero-endocrine cells (1998)
    Springer
    Histochemistry and cell biology 109 (1998), S. 161-165 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The binding of the fucose-specific lectin, Ulex europaeus agglutinin (UEA-I), to entero-endocrine cells was studied in the ileum and caecum of humans, rabbits, rats, and mice. In all species investigated, numerous cells scattered in the crypt and villus epithelia intensely bound the UEA-I lectin. These cells proved to be argyrophilic and were identified as enterochromaffin cells and peptide tyrosine tyrosine cells by immunohistochemistry. They mostly reached the gut lumen (”open type”) by slender cellular processes. At the ultrastructural level, fucose binding sites were located in the matrix of the electron-dense secretory granules of these cells and in the glycocalyx covering their apical membrane. The results show that in various mammalian species entero-endocrine cells of defined types express fucose-bearing glycoconjugates. The presence of fucose residues in the apical membrane of entero-endocrine cells indicates that this membrane domain has a specialized composition of intramembranous glycoconjugates which could be involved in receptive and/or secretory functions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050213
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  • 6
    Electronic Resource
    Electronic Resource
    Identification of M-cells in the rabbit tonsil by vimentin immunohistochemistry and in vivo protein transport (1995)
    Springer
    Histochemistry and cell biology 104 (1995), S. 211-220 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The rabbit palatine tonsil was studied by electron microscopy to determine whether M-cells similar to those of the Peyer's patches exist in the tonsil epithelium. A subpopulation of crypt epithelial cells was found with long, irregularly shaped microvilli, small cytoplasmic vesicles and engulfing intraepithelial lymphocytes and macrophages. Using ultrastructural immunohistochemistry, vimentin, the rabbit marker for intestinal and bronchial M-cells, was detected in the cytoplasm of these cells, whereas no vimentin immunoreactivity was found in the remaining epithelial cells. The vimentin filaments surrounded the nucleus of the presumed M-cells and lay beneath the plasma membrane that surrounded intraepithelial lymphocytes. In vivo experiments using horseradish peroxidase as tracer revealed that this protein was endocytosed by the presumed M-cells and transported to the intercellular spaces between epithelial cells and lymphocytes. The results indicate that specialized epithelial cells exist in the tonsil which have morphological characteristics similar to those of intestinal M-cells, are in close contact to cells of the immune system, are positive for the rabbit M-cell marker vimentin, and are capable of antigen uptake and transcytosis. It is therefore concluded that M-cells are present in the tonsil and probably play a role in the initiation of immune responses to orally delivered antigens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01835154
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  • 7
    Electronic Resource
    Electronic Resource
    The role of M cells in the protection of mucosal membranes (1997)
    Springer
    Histochemistry and cell biology 108 (1997), S. 455-470 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  The mucosa-associated lymphoid tissues continuously take up antigenic matter from the lumen to generate immune responses or to maintain immune tolerance. This antigen sampling is performed by highly specialised epithelial cells, the membranous (M) cells of the dome epithelia. M cells possess a unique ultrastructure and lie in close contact to lymphoid cells. They endocytose soluble and solid substances, including entire microorganisms, at their apical membrane, transport these in vesicles to their basolateral membrane and exocytose them to the intercellular space. This review summarises the structural and functional peculiarities of M cells in different species and at the different sites of lymphoid tissue along the digestive and respiratory tracts. Specialisations of M cells for antigen uptake and transport comprise the composition of their apical membrane and its glycocalyx, a modified cytoskeleton as compared to enterocytes and a pocket-like invagination of the basolateral membrane populated by lymphocytes and macrophages. Besides ultrastructural characteristics, histochemical markers are listed that are currently available for detecting M cells by light microscopy. The origin, differentiation and distribution of M cells and other epithelial cell types of the dome epithelium are outlined. As M cells are used as entry sites by various pathogens and, in the future, might be employed for the oral application of vaccines and drugs, the clinical relevance of M cells in health and disease is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004180050186
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  • 8
    Electronic Resource
    Electronic Resource
    Lymphocyte subsets in bronchoalveolar lavage after exposure to Actinobacillus pleuropneumoniae in pigs previously immunized orally or by aerosol (1995)
    Springer
    Lung 173 (1995), S. 233-241 
    Details
    ISSN: 1432-1750
    Keywords: Bronchoalveolar lavage ; Actinobacillus (Haemophilus) pleuropneumoniae ; Immunization ; Lymphocyte subsets ; Pig
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Young pigs were immunized with the lung-pathogenic bacterium Actinobacillus (Haemophilus) pleuropneumoniae by aerosol or orally using viable and inactivated bacteria. The cellular changes in the bronchoalveolar lavage (BAL) were studied in repeated lavages after the pigs were infected with live bacteria. The nucleated cells in the BAL were differentiated and lymphocyte subsets determined. There were no major differences between the two routes of immunization or between viable and inactivated bacteria. The immunization induced an increase in all lymphocyte subsets studied and in the appearance of plasma cells and lymphoid blasts. The infection did not cause a further increase except in granulocytes. The lack of a booster-type increase in lymphocytes in the BAL might indicate a different immunologic reaction of the lung or that lymphocytes of the BAL do not represent lung lymphocytes in general. The protective effect of the immunization might be deduced from the increase in lymphocytes after immunization but not from the reaction pattern after infection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00181875
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  • 9
    Electronic Resource
    Electronic Resource
    Electrochemical investigations on the bulk glass forming Zr55Cu30Al10Ni5 alloy (1997)
    Weinheim [u.a.] : Wiley-Blackwell
    Materials and Corrosion/Werkstoffe und Korrosion 48 (1997), S. 293-297 
    Details
    ISSN: 0947-5117
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Elektrochemische Untersuchungen an Massivproben der glasbildenden Zr55Cu30Al10Ni5-LegierungEs ist das elektrochemische Verhalten der amorphen Zr55Cu30Al10Ni5 Legierung, welche in Form zylindrischer massiver Proben mit einem Durchmesser von 7 mm hergestellt wurde, untersucht worden. Zyklische potentiodynamische Polarisationsmessungen, die an den Querschnittsflächen der Proben in luftgesättigten und stickstoffgespülten Sulfat- bzw. Hydroxidlösungen ausgeführt wurden, zeigen, daß die Legierung sehr schnell schützende Passivschichten mit geringer Elektronenleitfähigkeit bildet, die in einem weiten pH-Wert- und Potentialbereich stabil sind. Anodische Schichtbildungsreaktionen werden charakterisiert. In chloridhaltigen Elektrolyten besteht eine Lochkorrosionsanfälligkeit des massiven Materials. Die Wirkung kristalliner Defekte als aktive Plätze für die Initiierung von lokalen Korrosionsprozessen wird kritisch diskutiert.
    Notes: The electrochemical behaviour of the Zr55Cu30Al10Ni5 amorphous alloy prepared as cylindrical bulk samples with 7 mm diameter has been investigated. Cyclic potentiodynamic polarization measurements carried out on the cross section areas of the samples in air-saturated and nitrogen-purged sulphate and hydroxide solutions, respectively, show that the alloy rapidly forms protective passive layers with low electron conductivity which are stable in a wide pH-value and potential range. Anodic layer formation reactions are characterized. In chloride containing electrolytes a pitting corrosion susceptibility of the bulk material exists. The effect of crystalline defects as active sites for the initiation of localized corrosion processes is critically discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/maco.19970480504
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