[3DEM] F30 cartridge problem

[Z Hong Zhou]

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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