[3dem] Gatan 910 multi specimen cryo transfer holder-- not for the neophyte
matthias.wolf at oist.jp
Tue Oct 31 08:17:40 PDT 2017
Thank you very much for your detailed reply. This is indeed very helpful.
But I don’t fully understand the anatomy of he holder - When you talk about the “cassette”, what exactly do you mean? From the brochure it looks just like a 626 with 3 wells at the tip of the holder rod, into which a naked grid is loaded directly and secured by split ring (presumably a more “springy” version of the ring used in the 626). This would be consistent with your “old design”. Does the entire tip of the holder come off?
Or are you loading assembled FEI cartridges (ring, grid, C-clip) unsecured onto the holder and those can fall out?
Their height would probably be too thick for locking them down with the split ring. I remember that silicon nitride grids, which are about 0.4 micron thick, could barely be clipped in the 626.
If so, is there a dedicated version of the 910, which is designed to take FEI cartridges (the “new design”)?
Also, how many hours of working time do you get before refilling the dewar?
Is a movie rate camera required for drift compensation at anything but low mag?
Thanks, Leo, for pointing out a newer model - I will inquire.
On Oct 31, 2017, at 21:37, Bowman, Valorie D <vdb at purdue.edu<mailto:vdb at purdue.edu>> wrote:
We have one. It is both great and terrifying. I have used it to screen 6 cryo conditions in an afternoon. BUT, it has one awful design flaw- it is incredibly easy to drop the cassette into the column. If a person is looking at the 3rd grid and turns the grid selector the wrong direction, & plop! Gravity immediately pulls the left end of the cassette down off the edge of the stage, the right end pivots up off the ball on the end of the rod, and the whole thing falls out into the abyss.
We have one of the older models, and that design was far superior. Loading was more difficult, but this risk does not exist with the grids mounted in wells in the sample rod itself.
Both models take 15-20 minutes longer to stabilize in the microscope after insertion, and they take longer to cool down, but I count that a fair trade off for 3 samples at once. The split-ring clip rings are not too different from the 626 version; it's just easier to accidentally push through a grid.
By far, the worst thing is the lack of a real "lock" onto the cartridges. This holder was tested by one of our best people, and he dropped the cartridge in the scope the very first time he used it! I know it is only a matter of time before it happens again-- and the cartridges are not cheap, plus potential scope down time if it blocks the beam, pole pieces, etc.
It's a great holder, but if you have a wide range of levels of users, it might not be one for everyone.
vdb at purdue.edu<mailto:vdb at purdue.edu>
EM Facility Laboratory Manager/
Senior Research Electron Microscopist
Purdue Cryo EM Facility
From: 3dem <3dem-bounces at ncmir.ucsd.edu<mailto:3dem-bounces at ncmir.ucsd.edu>> on behalf of Matthias Wolf <matthias.wolf at oist.jp<mailto:matthias.wolf at oist.jp>>
Sent: Monday, October 30, 2017 11:00 PM
To: 3dem at ncmir.ucsd.edu<mailto:3dem at ncmir.ucsd.edu>
Subject: [3dem] Gatan 910 multi specimen cryo transfer holder
We are considering the purchase of a Gatan 910 cryo transfer multi specimen side entry holder.
Does anyone have experience with this holder?
The specs with respect to stability are identical to the 626 (the alternative), but I don’t know how it will perform in practice. It can take 3 grids.
The holder will be used for screening of a larger number of cryo samples. Cryo tomography is not a requirement. Due to possible contamination during unloading, the idea is not to reuse screened grids – once plunging conditions are established, a second grid frozen under identical conditions on a reproducible plunging bot will be used for data collection on a higher end cryo TEM with DED and autoloader. We hope to accelerate the cryo screening by loading 3 grids at once instead of one at a time and to reduce frosting and ice contamination with less cryo transfers. This step aims at offloading screening from the expensive high end tools and to maximize their beam time for productive data collection. The holder will also be used at room temperature for negative stained samples before cryo screening, both of which will act as triage steps for samples of insufficient quality.
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