PS Re: [3dem] "leopard skin" ice

[Jacob Brink]

Willem,

I know you're thinking of cubic ice. The ice pattern that we've seen was present immediately after opening the shutter. Moreover, whenever we did show electron diffraction - during the NIBSC cryo-EM course we'd have to prove that the ice was vitreous - we never saw the shape rings indicative of cubic ice.

Jaap


On Nov 21, 2013, at 4:31 PM, Willem Tichelaar <w.tichelaar at online.de> wrote:

> PS See also Dubochet et al. (1988) Quart. Rev. Biophys. 21, pp. 129-228, Fig. 32 c and d
> 
> Hi Frank,
> 
> I thought that the contamination with a leopard skin pattern arises in the microscope when the vacuum is not clean i.e. when the partial water pressure near the specimen is not low enough. Then, the contamination that you see should increase with time though.
> 
> Good luck,
> Willem.
> 
> On 11/20/13 6:23 PM, frankpolzer at physik.hu-berlin.de wrote:
>> Hi again,
>> 
>> Please find attached an example image of the ice I observed.
>> 
>> Cheers,
>> Frank
>> 
>> 
>>> Dear all,
>>> 
>>> During the last weeks, I frequently observe what I believe is so-called
>>> leopard skin ice in my vitrified samples (plunge frozen in ethane using
>>> Mark IV Vitrobot).
>>> 
>>> What again is the reason for this type of ice and how can this be avoided?
>>> 
>>> Thanks for your help in advance,
>>> 
>>> Frank
>>> 
>>> 
>>> Dr. Frank Polzer
>>> 
>>> TEM Group
>>> Insitute of Physics
>>> Humboldt Universität zu Berlin
>>> Newtonstraße 15
>>> 12489 - Berlin
>>> Tel.: +49 30 2093-4995 (office)
>>> Tel.: +49 30 2093-7829 (TEM)
>>> Fax: +49 30 2093-7886
>>> 
>>> 
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> 
> -- 
> Dr. Willem Tichelaar
> Richard-Drach-Str. 5
> 69123 Heidelberg, Deutschland
> 
> phone: +49 (0)6221 779409; fax: +49 (0)6221 779411
> e-mail: w.tichelaar at online.de
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