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  • 78.55DS  (1)
  • Cell division  (1)
  • Springer  (2)
  • 2005-2009
  • 1990-1994
  • 1985-1989  (2)
  • 1945-1949
  • 2008
  • 1986  (2)
  • 1946
Collection
Publisher
  • Springer  (2)
Years
  • 2005-2009
  • 1990-1994
  • 1985-1989  (2)
  • 1945-1949
Year
  • 2008
  • 1986  (2)
  • 1946
  • 1
    ISSN: 1432-0630
    Keywords: 78.55DS ; 61.80Jh ; 71.35 +z
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract We report on a photoluminescence study of silicon samples subjected to different dry etching processes. Several luminescence lines, known from defects produced by high-energy irradiation, manifest damage of the crystalline material. Noble gas ion beam etching (using Ne+, Ar+, Kr+, and Xe+) with ion energies as low as 400 eV produces characteristic luminescence lines which correspond to defects within a 200–300 Å thick surface layer. Incorporation of carbon during CF4 reactive ion etching produces the familiar G-line defect. The G-line photoluminescence intensity in our samples is directly correlated with the substitutional carbon concentration, as determined by infrared absorption measurements before the etch process; we therefore suggest that a simple method to determine the substitutional carbon concentration in a crystalline silicon sample is a standard dry etching process and a comparison of the resulting G-line photoluminescence intensity to a calibrated sample. The sensitivity of this method seems to be better than 1014 carbon atoms/cm3.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 131 (1986), S. 1-10 
    ISSN: 1615-6102
    Keywords: Cell division ; Lomentaria ; mitosis ; Red algae ; Rhodophyta ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Mitosis in the marine red algaLomentaria baileyana (Rhodymeniales, Rhodophyta) was studied with the electron microscope. Nucleus associated organelles known as polar rings (PRs) migrate to establish the division poles at prophase. At prometaphase, shallow invaginations in the nuclear envelope (NE) form on two sides of each PR and soon rupture. The gaps that are consequently formed contain several small fragments of NE. A larger region of NE remains intact between the two gaps. By metaphase several cisternae of perinuclear endoplasmic reticulum (PER) have enclosed most of the nucleus but remain absent from the polar regions. The nucleolus disperses partially and a typical metaphase plate of chromosomes is formed. Each PR has disjoined into separate proximal and distal portions. MTs converge widely on all regions of the polar area, but do not extend into the cytoplasm. Some MTs end near or at the chromosomes while others extend slightly farther past the chromosomes or diagonally to the NE. As chromosomes move to opposite poles at anaphase, they are accompanied by nucleolar material. An interzonal midpiece (IZM) is created as the pole to pole distance increases and the NE remains intact except for the polar gaps. Following detachment from the IZM, the daughter nuclei are separated by a large central vacuole as a cleavage furrow develops and eventually constricts to form two cells following pit connection formation. It is suggested that mitosis inLomentaria represents an evolutionary intermediate between that seen in the higher and lower groups of red algae. This conclusion is in agreement with conventional morphological and light microscopic criteria used to placeLomentaria in theRhodymeniales, which is considered to be the next to most advanced order in theRhodophyta.
    Type of Medium: Electronic Resource
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