[3dem] "leopard skin" ice

[Shi PhD, Dan]

Hi Frank,
The leopard skin is comprised of nano-ice/salt crystals, they might come
from slow ice contamination in high vacuum environment with small leaks
which were observed by number of labs, and another possibility is the
solution containing certain type of salts/agents which are precipitated or
crystallized during freezing, the third one could be the cooling liquid
was too 'warm'. 
You may try to freeze your sample at different lab or freeze a simple
buffer like 20 mM NaCl using your Vitrobot.
Good luck,

Dan Shi
JFRC, HHMI
19700 Helix Dr
Ashburn, VA 20147  

On 11/20/13 12:23 PM, "frankpolzer at physik.hu-berlin.de"
<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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