The article on measuring diatom shell strength that Dr. Currey refered to is
"Architecture and material properties of diatom shells provide effective
mechanical protection", Nature 421, 841 - 843, Feb 23, 2003
"Currey, J.D." <[log in to unmask]> wrote:
> Peter
> Your student has a real problem here. However: 'The best is the enemy
> of the good' (you know how Julian just loves quotations), and she'll
> just have to do the best she can.
> I agree completely with what Richard B said. Microhardness will at
> least give you something, and microhardness is loosely correlated with
> abrasion resistance via Archard's law (it's on the web!). Microhardness
> testers are pretty common in engineering departments and reasonably easy
> to use. Nanohardness is an order of magnitude more difficult, and
> expensive, and not to be recommended except in extremis.
> Definitely don't try to treat in bulk.
> Freezing in sea water is I think a good idea. Most mineralised tissues
> are reasonably forgiving of having been frozen and then thawed.
> Preservation in alcohol or formol definitely not a good idea.
> Strength of the whole structures of things like copepods could be tested
> using small testing equipment, but normalising to compare like with like
> would be v. difficult. Fish larvae and salps of course are not amenable
> to testing in any sensible way, and hardness is meaningless in their
> case, though Julian could probably come up with an ingenious way of
> testing their TOUGHNESS.
> I read VERY recently of a report, but I'm damned if I can remember
> where, of people who had been testing diatom strength using a glass rod
> as a load 'cell' They found quite nice relationships, as I remember,
> between edibility and various mechanical properties. But all these
> kinds of methods will only make sense on hard tissues, not sloppy salps!
> A question that occurred to me is whether these prey will have been
> partially digested already. If they have, that's an added problem, of
> course.
> Good luck
> John
>
>
> Professor John Currey
> Department of Biology
> Area 9
> PO Box 373
> University of York
> York YO10 5YW. UK
>
> email [log in to unmask]
> tel +44 (0)1904 328589
> fax +44 (0)1904 328505
Mark H. Dorfman, MSPH
Environmental Scientist
26 West 27th Street, #62
New York, New York 10001
212-779-8721 Tel
212-679-0498 Fax
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