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Some observations on knife properties and sectioning mechanics during ultramicrotomy of plastic embedding media
Author(s) -
Helander Herbert F.
Publication year - 1974
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1974.tb03869.x
Subject(s) - materials science , bevel , composite material , microtome , enhanced data rates for gsm evolution , perpendicular , compression (physics) , microscopy , transmission electron microscopy , optics , nanotechnology , geometry , physics , mathematics , mechanical engineering , telecommunications , computer science , engineering
SUMMARY The edge and the trough surface of ultramicrotome glass knives were studied by interference light microscopy and electron microscopy. Particular attention was paid to the region which is commonly used for microtomy; here the bevel angle was calculated to 50–55°. The edge was serrated, even in the region used for sectioning, where the indentations measured up to 20 nm in depth. The imprints of edge serrations left on the sectioned material (Vestopal) were studied by electron microscopy. Different embedding materials displayed different degrees of compression when sectioned in the ultramicrotome: with Epon the compression was less than 10%, whereas methacrylate was compressed by more than 30%. Different trough fluids were tested: aqueous solutions of ethanol, acetone and dioxane gave less compression than pure water. However, the compression could also be reduced by exposing compressed Vestopal sections to these solutions. The direction and magnitude of the cutting force was measured with transducers during the sectioning of Vestopal blocks. Thus ∼0·3 μm wide sections cut at a feeding rate of 80 nm and a speed of 2 mm/sec required a cutting force of about 8 mN. The direction of the forces was 8–15° from the plane of cutting.