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<div class="moz-cite-prefix">Hello together,</div>
<div class="moz-cite-prefix">what would be the best or maximum time
to pump the airlock at the Tecnai Spirit Scope??</div>
<div class="moz-cite-prefix">I changed allready from 30 seconds to
45 seconds.</div>
<div class="moz-cite-prefix">Vacuum values look good.<br>
</div>
<div class="moz-cite-prefix">We suffer a lot from contamination and
different ice formations since quite some time... every grid looks
different.</div>
<div class="moz-cite-prefix">How can we check if the clip ring at
the Gatan holder 626 is perfectly adjusted?</div>
<div class="moz-cite-prefix">I mean this is the place where the grid
has to have the perfect contact a heat bridge to the holder.<br>
</div>
<div class="moz-cite-prefix">How can we check cryo-box or
cryo-shield?</div>
<div class="moz-cite-prefix">Kind regards <br>
</div>
<div class="moz-cite-prefix">Jörg</div>
<div class="moz-cite-prefix"><br>
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<pre class="moz-signature" cols="72">****************************
Jörg Bürger
Charité - Universitätsmedizin Berlin
Institut für Medizinische Physik und Biophysik
Charitéplatz 1, CCO - Virchowweg 6
10117 Berlin
Max Planck Institut für molekulare Genetik
Microscopy and Cryo-EM microscopy group
Ihnestr. 63-73
14195 Berlin
tel. 030-8413-1644/1278
fax. 030-8413-1385
email. <a class="moz-txt-link-abbreviated" href="mailto:buerger@molgen.mpg.de">buerger@molgen.mpg.de</a></pre>
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<div class="moz-cite-prefix">On 05.01.2022 14:51, Wim Hagen wrote:<br>
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<blockquote type="cite"
cite="mid:F27011F6-B319-4E1F-9A4E-1885790C15ED@embl.de">
<pre class="moz-quote-pre" wrap="">In the very early days it was even suggested to use ethane to "coat the sample” as a measure of preventing transfer contamination:
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Best,
Wim
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<pre class="moz-quote-pre" wrap="">On 5. Jan 2022, at 14:45, Reinhard Rachel <a class="moz-txt-link-rfc2396E" href="mailto:Reinhard.Rachel@biologie.uni-regensburg.de"><Reinhard.Rachel@biologie.uni-regensburg.de></a> wrote:
I see your point, Wim.
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<pre class="moz-quote-pre" wrap="">On systems with side-entry cryo-holders, the pump-time for holder insertion
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<pre class="moz-quote-pre" wrap="">is limited and pressure is not measured by the vacuum system.
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<pre class="moz-quote-pre" wrap="">
it is measured on our 2100F.
I doubt that 20 sec is a good time for cryo-transfer. Vacuum always needs
time!
the sample temperature should be kept low enough for quite some time (120 /
180 sec, at least).
but the vacuum improves quite considerable when going from short pump times
(20sec) up to 180 sec. or even longer.
this is at least the case for the air-lock/gonio of our 2100F (holder with two
O-rings ...).
thus:
- tilting to -30 or -35 degrees is fully sufficient
- pumping up to 120/180 sec (or even longer?) is fine, and the sample looks
fine, too.
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<pre class="moz-quote-pre" wrap="">If a grid
contains a lot of frozen ethane (from a fast transfer from ethane into
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<pre class="moz-quote-pre" wrap="">liquid
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<pre class="moz-quote-pre" wrap="">nitrogen on the plunge freezer), this ethane will sublimate in vacuum: too
much ethane and/or short pump time -> column vacuum crashes as the ion
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<pre class="moz-quote-pre" wrap="">getter
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<pre class="moz-quote-pre" wrap="">pumps see a lot of ethane coming in when the holder is inserted.
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<pre class="moz-quote-pre" wrap="">
this is the point - thank you, Wim.
thus, I think Tobias & Co may try longer times for pre-pumping in the
air-lock?
I do not know this type of air-lock in the Halo - but it might work.
kind regards,
Reinhard
--
Prof. Dr. Reinhard Rachel
University of Regensburg
Centre for EM / Anatomy
Faculty of Biology & Preclin. Med.
Universitaetsstrasse 31
D-93053 Regensburg - Germany
tel +49 941 943 -2837, -1666
mail <a class="moz-txt-link-abbreviated" href="mailto:reinhard.rachel@biologie.uni-regensburg.de">reinhard.rachel@biologie.uni-regensburg.de</a>
office: VKL 3.1.29
member of the IFSM board
Next microscopy conferences:
- MC2023, DGE: 26.2.-2.3. 2023
- next European EM conf.: EMC2024 in Kopenhagen, August 2024
- IMC20 in Busan, South Korea: Sept, 2023
- next Microbiol. conferences: VAAM 20-23 Febr 2022 Düsseldorf
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<pre class="moz-quote-pre" wrap="">_______________________________________________
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<pre class="moz-signature" cols="72">--
****************************
Jörg Bürger
Charité - Universitätsmedizin Berlin
Institut für Medizinische Physik und Biophysik
Charitéplatz 1, CCO - Virchowweg 6
10117 Berlin
Max Planck Institut für molekulare Genetik
Microscopy and Cryo-EM microscopy group
Ihnestr. 63-73
14195 Berlin
tel. 030-8413-1644/1278
fax. 030-8413-1385
email. <a class="moz-txt-link-abbreviated" href="mailto:buerger@molgen.mpg.de">buerger@molgen.mpg.de</a></pre>
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