[3dem] Strange ice behaviour - advice welcome from community!

[Halldorsson, Steinar]

Dear all

Seems there is a clear consensus on that the sample is warming up by loss
of therma contact and we have some really useful advice. Thanks a lot
everyone for the input!
Will for sure try prying those split rings apart.

Best wishes,
Steinar

On Tue, 10 Dec 2024 at 14:38, Steinar Halldorsson <
steinar.halldorsson at roche.com> wrote:

> Dear 3DEM community
>
> Thanks for years of great forum discussions!
>
> The EM team at Roche in Basel has recently been observing some strange
> events in our JEM1400 microscope and we are curious if other users have
> seen this or if there have even been previous posts about this on the forum.
>
> Stochastically, some of our grids appear to "sublimate" when they are
> placed under the beam in the microscope. The observation is as such:
>
> After a minute or two of illumination of a grid in low mag or higher mag,
> it seems that the beam induces some sort of a cascade that seems to dry up
> the entire grid and leaves only strings or lumps of protein most likely. At
> the beginning the grid is full of vitreous buffer and within about 5-10
> seconds the entire buffer/water seems to have sublimated (see images
> attached of the dried up grids). One can even watch the grid live as it
> dries up.
>
> Some key facts:
> - Seems that frequency of this event has increased in the last couple of
> months
> - We have seen this only on our JEM1400 microscope and we use a Gatan 910
> multi specimen cryo holder
> - This has not been observed on our cryoARM (Jeol)
> - This happens independent of the slot used in the cryo holder
> - This only happens if a grid has been illuminated (not just stored in the
> holder)
> - Higher beam intensity appears to increase the speed of this happening
> but this is not as clear yet
> - We've monitored the holder temperature and it doesn't spike, seems to be
> stable below -170 deg C.
> - Happens with multiple samples and with multiple grid types (quantifoils,
> hexafoils, ultrafoils)
> - Happens with grids frozen from our Leica plunger and with the CryoWriter
> - We have high grade ethane and the bottle has not changed for over a year
> (we have a 10 L bottle)
>
> Our thoughts after a number of discussions:
> - Maybe we have a systematic contamination of something on the grids that
> causes this phenomena - unclear what it could be though
> - Is freezing problematic, due to temperature of ethan or other factors?
> Is ethan forming a layer outside the vitreous buffer? Does it get embedded
> even? (Would ethane even exhibit this kind of behaviour?)
> - Perhaps this is from the grids themselves, do other users observe this
> for more recent grid batches?
> - Is our storage dewar contaminated with something that attaches to our
> grids that reacts with the electron beam? Do some plastics degrade in
> liquid nitrogen?
>
>
> If anyone has observed similar issues we would like to hear from you, and
> even better if you have identified the source of those issues we would of
> course really like to hear from you.
>
> Hope to hear from some of you soon!
> Best wishes,
> Steinar
>
>
> --
> Steinar Halldórsson DPhil (he/him)
>
> F. Hoffmann-La Roche AG
> pRED/Lead Discovery/Structural Biology
> Grenzacherstrasse 124, 006/OG03, 4070 Basel, Switzerland
> Email: steinar.halldorsson at roche.com
> Tele: +41 61 68 82374
>
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