[3DEM] F30 cartridge problem

[Bob Grassucci]

Hi Bill and Hong,
         This sticking of the cartridge may be from contamination residing 
on either the inner conical surface of the stage or the outer conical 
surface of the cartridge that is acting like a glue.  The warm surface of 
the cartridge (or the pressure between the surfaces) would melt it and 
after it cools down it will again solidify.  Is there a significant amount 
of contamination building up on your sample if you leave it in for 
overnight?  One thing to try is to use the plastic screw rod to break the 
bond between the cartridge and specimen stage by pushing into the cartridge 
a few times (without turning).  I have also sent this to the tecnai user 
list in case there are any other Polara owners experiencing this problem 
there.  Another potential reason could be the position of the plastic screw 
rod into the cartridge.  There is the possibility that the plastic rod is 
not becoming fully disengaged from the cartridge.  There must be sufficient 
displacement of this rod so that it is fully removed.  There is a spring 
that should push the plastic rod out of the stage once it is 
disengaged.  Please contact me if you have any further questions.  Good luck.
         Bob

At 08:11 PM 10/13/2004 -0500, you wrote:

>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>http://hub.med.uth.tmc.edu/~hong
>
>Ph: 713.500.5358  Fax:713.500.0730, Email: 
><mailto:Z.H.Zhou at uth.tmc.edu>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 
><mailto:Christine.M.Haverkorn at uth.tmc.edu>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
>
>
>
>**** Messages to this list are automatically archived ***
>
>**** Please limit quoting of previous postings to the bare minimum ****
>
>
>
>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
>
>
>
>
>
>--
>
>For information on how to subscribe/unsubscribe/etc., send mail to
>
>3dem-request at 3dem.ucsd.edu with the text "help" in the body of the
>
>message.

********************************
Robert Grassucci
Howard Hughes Medical Institute
Wadsworth Center
Empire State Plaza
Albany, NY 12201-0509

bobg at wadsworth.org
Phone: (518)474-5821
Fax:	(518)486-2191