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  • 1
    Electronic Resource
    Electronic Resource
    Positron annihilation investigation of porous silicon heat treated to 1000 °C (1998)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 84 (1998), S. 6559-6564 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Positron lifetime and Doppler broadening spectroscopies were applied to investigate a porous silicon film subjected to heat treatment in an argon atmosphere. Heating between 300 and 500 °C increased the mass of the film by 17% due to oxygen uptake and the concentration of open volume defects associated with the formation of an oxide layer on the silicon nanocrystallites increased by a factor of 3. Between 600 and 1000 °C their concentration decreased gradually to 1/2 the original concentration. Doppler broadening results indicate two distinct electron momentum distributions, one arising from open volume defects and one from pickoff annihilation of positronium at the pore walls caused by electrons with an unexpectedly narrow momentum distribution. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369028
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Abnormal deposition of type VII collagen in Kindler syndrome (1999)
    Springer
    Archives of dermatological research 291 (1999), S. 6-13 
    Details
    ISSN: 1432-069X
    Keywords: Key words Type VII collagen ; Basement membrane ; Integrins ; Kindler syndrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Kindler syndrome is an extremely rare genetic disorder with features of epidermolysis bullosa and poikiloderma congenitale. Approximately 70 cases have been documented in the past 50 years, but only a few investigations of the basement membrane components have been done on these patients. The aim of this study was to examine the components of the basement membrane zone in search of the pathobiological defect(s) responsible for the clinical findings from a female 16-year-old patient diagnosed with Kindler syndrome. This patient also suffered from advanced early-onset periodontal disease. Biopsies were taken from inflamed gingiva and noninflamed oral mucosa as part of periodontal treatment. The basement membrane zone was examined using immunofluorescence microscopy to bullous pemphigoid antigens 1 and 2, collagen types IV and VII, laminins-1 and -5, and integrins ·3‚1 and ·6‚4. The biopsies studied revealed blistering with trauma above the level of lamina densa based on distribution of type IV collagen and laminin-1 at the blister floor. In the noninflamed mucosa, discontinuous areas of the basement membrane zone were found. Expression of the basement membrane zone components and the integrins studied appeared otherwise normal with the exception of type VII collagen which was found in abnormal locations deep in the connective tissue stroma. Our results suggest that Kindler syndrome is associated with abnormalities in the construction of the basement membrane, especially in the expression of type VII collagen. These alterations are likely to play a role as etiological factors leading to blister formation and early onset periodontal disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004030050377
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  • 3
    Electronic Resource
    Electronic Resource
    Heat-Treatment Induced Modifications of Porous Silicon (1997)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 258-263 (Dec. 1997), p. 1725-1730 
    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.258-263.1725.pdf
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  • 4
    Electronic Resource
    Electronic Resource
    An Investigation of Porous Silicon by Means of Positron Annihilation (2000)
    Springer
    Journal of porous materials 7 (2000), S. 323-326 
    Details
    ISSN: 1573-4854
    Keywords: positron annihilation ; porous silicon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Positron lifetime spectroscopy has been used to investigate a porous silicon film subjected to heat treatments up to 1170°C. Annealings between 300 and 500°C resulted in a 17% mass increase of the film due to oxygen uptake following the effusion of hydrogen. The positron data also indicate that vacancy clusters are formed in the silicon oxide layer or the silicon oxide—silicon interface surrounding the nanocrystallites as oxygen replaces the effusing hydrogen. The vacancy cluster concentration, which may have a bearing on the photoluminescent properties, increased by a factor of three with heating to 500°C and then decreased to one-third the original value at higher temperatures. Above 900°C vacancy migration and clustering occurred, accompanied by visible deterioration of the film.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009625307658
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