[3DEM] F30 cartridge problem
Z Hong Zhou
Z.H.Zhou at uth.tmc.edu
Wed Oct 13 18:11:54 PDT 2004
Bill;
We have had the same problem for a couple of times already in
our new Polara G2 in the last couple of months. We were told by FEI an
engineer that this was due to the different temperatures between the stage
and the insertion rod. Their reasoning is that if you insert a cartridge at
room temperature (carbon film test specimen) into a cooled column (liquid
nitrogen), the cartridge will be "frozen" to the stage and it won't release
even after unscrewing. I could not possibly figure out how a dry copper
cartridge can possibly be frozen to a metal surface the high vacuum of the
column and was not convinced by their explanation. Nor do I have an
explanation myself.
I should indicate that during one of the two incidences we had,
the problem mysteriously disappeared after leaving the cartridge in the
stage overnight.
Hong
_________________________________________________________
Z. Hong Zhou, Ph.D., Assoc. Prof., http://hub.med.uth.tmc.edu/~hong
Ph: 713.500.5358 Fax:713.500.0730, Email: Z.H.Zhou at uth.tmc.edu
University of Texas - Houston, Medical School, 6431 Fannin, MSB2.280
Department of Pathology & Laboratory Medicine, Houston, TX 77030
Secretary support: Ms Chris Haverkorn 7135005316
Christine.M.Haverkorn at uth.tmc.edu
-----Original Message-----
From: owner-3dem at ncmir.ucsd.edu [mailto:owner-3dem at ncmir.ucsd.edu] On Behalf
Of Bill Tivol
Sent: Wednesday, October 13, 2004 7:37 PM
To: 3dem at ucsd.edu
Subject: [3DEM] F30 cartridge problem
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Dear List,
Lately we have been having trouble when trying to extract a
cartridge
from the stage into the insertion rod. The cartridge stays in the
stage after the thread has been unscrewed. This has occurred with
cartridges of all types--screw ring, c-clip, and flip-flop. The only
way we know that works to extract successfully is to put hot water in
the dewar on the insertion rod and heat the rod to ~50 C. Even this
method is not always successful, and, of course, if we wish to continue
studying a frozen-hydrated specimen, such as when taking a dual-axis
tilt series, such a warm-up is unacceptable. Has anyone 1) seen this
problem, 2) managed to determine the cause, and/or 3) found a way to
extract the cartridge that does not spoil the specimen? TIA for any
help.
Yours,
Bill Tivol, PhD
EM Scientist and Manager
Cryo-Electron Microscopy Facility
Broad Center, Mail Code 114-96
California Institute of Technology
Pasadena CA 91125
(626) 395-8833
tivol at caltech.edu
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