We are talking about the same containers. Actually, Jon Spear contacted me
today and indicated that the burrs are probably left-overs from the milling
process which were not cleaned out sufficiently. This explains the particles
and the vigorous boiling action caused by the abundance of nuclei for the
bubbles to form and not by lack of insulating capacity.
Ours must have been an isolated incident, since everybody else seems to be
quite happy with these vessels. So we may give them another shot ....
Cheers
Carsten
-----Original Message-----
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] Behalf Of Artem Evdokimov
Sent: Thursday, October 09, 2008 6:37 PM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] foam dewar usage ?
Maybe we're not talking about the same kind of container? We never had any kind
of particles** in ours and with the use of a lid the ice does not appear for
quite some time. We did not see 'vigorous boiling' either. If one leaves LN2 in
the open it would eventually ice up regardless of the nature of storage
container J
Artem
* calling foam LN2 container a 'Dewar' is a misnomer, James Dewar would not be
happy.
** there is a scenario in which particulates may form - and that is if a wet
container (i.e. not dried for long enough after previous use) is subjected to
LN2. This would rapidly freeze the water inside the foam layer and bust up the
pores, resulting in particulates.
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] On Behalf Of Van Den Berg,
Bert
Sent: Thursday, October 09, 2008 11:03 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] foam dewar usage ?
Funny indeed. Our experience has been as well that icing of the foam dewars
seems to be reduced compared to the "classical" ones.
Bert
-----Original Message-----
From: CCP4 bulletin board on behalf of Schubert, Carsten [PRDUS]
Sent: Thu 10/9/2008 9:15 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] foam dewar usage ?
Hmmm, that's funny. Our experience was quite the opposite. The first time we
used one of the darker small dewars we ended up with a lot of burr in the LN2.
Those got picked up by the cryo and we ended up with lilac particles embedded
inside the cryo. You can imagine the reaction when these particles showed up in
the mounting camera ....
We also noticed that the LN2 in these dewars actually ices up more rapidly as
compared to the glass dewars. We attribute this to the lower insulating
capacity of the foam dewars, which causes a vigorous boiling action and the
higher turbulence seems to suck in more ambient air. Needless to say the dewars
did not make it past the first use...
Carsten
-----Original Message-----
From: CCP4 bulletin board [mailto:[EMAIL PROTECTED] Behalf Of
[EMAIL PROTECTED]
Sent: Thursday, October 09, 2008 8:50 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] foam dewar usage ?
Yes, we use them all the time and they're great. Stuff does not slip on
the bottom like it does in the glass Dewars and the formation of ice is
greatly reduced. Plus, they're much easier to dry.
Artem
> Does anyone in the biocrystallogaphy community use foam dewars for
> handly liquid nitrogen and freezing/manipulating frozen protein
> crystals ?
