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<div>Hi Gongpu,</div>
<div><br>
</div>
<div>I had issues with pressure failures previously and found that anything that's left on the 'shoulders' of the carriers (that contacts the black diamond), such as yeast paste or gel, can prevent a tight seal from forming - so the carrier and diamond pop
apart during the freeze (hence the sudden drop in pressure on the pressure curve, and your curve looks similar to what I had). Not an issue in Bal-tec type freezers like the HPM100 since the whole chamber, not just the carrier interior, is pressurised.</div>
<div><br>
</div>
<div>Another possibility is an aging high pressure tube, which might not be contacting the cassette properly (if I remember rightly); in that case a session can start OK but might produce failures later on, as everything gets colder and the tube shortens.</div>
<div><br>
</div>
<div>Cheers,</div>
<div><br>
</div>
<div>Matt</div>
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<div>On 7 Oct 2015, at 17:09, <3dem-<a href="mailto:request@ncmir.ucsd.edu">request@ncmir.ucsd.edu</a>></div>
<div> wrote:</div>
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Today's Topics:<br>
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1. Re: pressure failure with Leica EM Pact2? (Paul Verkade)<br>
2. Re: pressure failure with Leica EM Pact2?<br>
(benoit.zuber@ana.unibe.ch)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Wed, 7 Oct 2015 17:00:36 +0100<br>
From: Paul Verkade <bixpv@bristol.ac.uk><br>
To: "Zhao, Gongpu" <goz1@pitt.edu><br>
Cc: "3dem@ncmir.ucsd.edu" <3dem@ncmir.ucsd.edu><br>
Subject: Re: [3dem] pressure failure with Leica EM Pact2?<br>
Message-ID: <D7108C4B-8F6F-4FD4-A6B7-C7AEEA4BF112@bristol.ac.uk><br>
Content-Type: text/plain; charset="us-ascii"<br>
<br>
Hi Gongpu,<br>
<br>
Indeed pressure should go up to around 2050 bar.<br>
<br>
A few things to check (which you probably already did).<br>
If you turn the blue knob on the side you can adjust the pressure, try adjusting that.<br>
Is the incoming pressure from the compressor OK (about 10bar)?<br>
<br>
Let me know if it works (or not), otherwise I can think of a few other things to try / check.<br>
<br>
Good luck,<br>
Paul<br>
__________________________________<br>
Paul Verkade PhD FRMS<br>
Reader in Cell Imaging<br>
Wolfson Bioimaging Facility<br>
Schools of Biochemistry and Physiology & Pharmacology<br>
Biomedical Sciences Building<br>
University of Bristol<br>
University Walk<br>
BS8 1TD Bristol<br>
United Kingdom<br>
<br>
tel.+44-117-3312179<br>
Fax. +44-117-3312168<br>
mail: p.verkade@bristol.ac.uk <mailto:p.verkade@bristol.ac.uk><br>
websites:<br>
http://www.bristol.ac.uk/biochemistry/research/pv.html <http://www.bristol.ac.uk/biochemistry/research/pv.html><br>
http://www.bris.ac.uk/phys-pharm/research/staffresearch/paulverkade.html <http://www.bris.ac.uk/phys-pharm/research/staffresearch/paulverkade.html><br>
http://www.bristol.ac.uk/biochemistry/wbif <http://www.bristol.ac.uk/biochemistry/wbif><br>
<br>
<blockquote type="cite">On 6 Oct 2015, at 20:42, Zhao, Gongpu <goz1@pitt.edu> wrote:<br>
<br>
Dear All,<br>
<br>
We are experiencing a pressure failure problem during high pressure freezing using Leica EM Pact . For successful freezing, the curve is smooth and pressure should go up to 2000 bar. But right now, the curve is fuzzy, at some points it drops and the small display
shows the pressure is failure. I have attached an image of the bad curve. Any insights about what might cause the problem and how to fix it would be greatly appreciated? Thank you very much.<br>
<br>
gongpu<br>
<br>
GONGPU ZHAO, PH.D.<br>
Research Associate<br>
Department of Structural Biology<br>
University of Pittsburgh School of Medicine<br>
3501 5th Ave. RM2054, Pittsburgh, PA 15260<br>
<br>
<pressure_failure.jpg>_______________________________________________<br>
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Message: 2<br>
Date: Wed, 7 Oct 2015 16:09:06 +0000<br>
From: <benoit.zuber@ana.unibe.ch><br>
To: <bixpv@bristol.ac.uk>, <goz1@pitt.edu><br>
Cc: 3dem@ncmir.ucsd.edu<br>
Subject: Re: [3dem] pressure failure with Leica EM Pact2?<br>
Message-ID: <D23B0EA8.17799%benoit.zuber@ana.unibe.ch><br>
Content-Type: text/plain; charset="iso-8859-1"<br>
<br>
Hi Gongpu,<br>
<br>
One more test suggestion: does this behaviour happen with more than one type of specimen carrier (e.g. Membrane carriers vs copper tubes)? I have experienced with two EMPACT2 machines that after a few years of usage the tubes burst if you shoot at 2000 bars
and you get a complete pressure failure, but this is not the case here. The solution to this tube problem is simply to reduce a bit the pressure, to around 1900 bars. Since we do CEMOVIS, we can check by electron diffraction that the sample is indeed vitrified
so we are not worried to work slightly below the optimal pressure value.<br>
<br>
Best wishes<br>
Ben<br>
<br>
De : 3dem <3dem-bounces@ncmir.ucsd.edu<mailto:3dem-bounces@ncmir.ucsd.edu>> on behalf of Paul Verkade <bixpv@bristol.ac.uk<mailto:bixpv@bristol.ac.uk>><br>
Date : mercredi, 7 octobre 2015 18:00<br>
? : "Zhao, Gongpu" <goz1@pitt.edu<mailto:goz1@pitt.edu>><br>
Cc : "3dem@ncmir.ucsd.edu<mailto:3dem@ncmir.ucsd.edu>" <3dem@ncmir.ucsd.edu<mailto:3dem@ncmir.ucsd.edu>><br>
Objet : Re: [3dem] pressure failure with Leica EM Pact2?<br>
<br>
Hi Gongpu,<br>
<br>
Indeed pressure should go up to around 2050 bar.<br>
<br>
A few things to check (which you probably already did).<br>
If you turn the blue knob on the side you can adjust the pressure, try adjusting that.<br>
Is the incoming pressure from the compressor OK (about 10bar)?<br>
<br>
Let me know if it works (or not), otherwise I can think of a few other things to try / check.<br>
<br>
Good luck,<br>
Paul<br>
__________________________________<br>
Paul Verkade PhD FRMS<br>
Reader in Cell Imaging<br>
Wolfson Bioimaging Facility<br>
Schools of Biochemistry and Physiology & Pharmacology<br>
Biomedical Sciences Building<br>
University of Bristol<br>
University Walk<br>
BS8 1TD Bristol<br>
United Kingdom<br>
<br>
tel.+44-117-3312179<br>
Fax. +44-117-3312168<br>
mail: p.verkade@bristol.ac.uk<mailto:p.verkade@bristol.ac.uk><br>
websites:<br>
http://www.bristol.ac.uk/biochemistry/research/pv.html<br>
http://www.bris.ac.uk/phys-pharm/research/staffresearch/paulverkade.html<br>
http://www.bristol.ac.uk/biochemistry/wbif<br>
<br>
On 6 Oct 2015, at 20:42, Zhao, Gongpu <goz1@pitt.edu<mailto:goz1@pitt.edu>> wrote:<br>
<br>
Dear All,<br>
<br>
We are experiencing a pressure failure problem during high pressure freezing using Leica EM Pact . For successful freezing, the curve is smooth and pressure should go up to 2000 bar. But right now, the curve is fuzzy, at some points it drops and the small display
shows the pressure is failure. I have attached an image of the bad curve. Any insights about what might cause the problem and how to fix it would be greatly appreciated? Thank you very much.<br>
<br>
gongpu<br>
<br>
GONGPU ZHAO, PH.D.<br>
Research Associate<br>
Department of Structural Biology<br>
University of Pittsburgh School of Medicine<br>
3501 5th Ave. RM2054, Pittsburgh, PA 15260<br>
<br>
<pressure_failure.jpg>_______________________________________________<br>
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