Hi everyone,
Apologies for any confusion my previous posting may have caused. Here
are a few clarifications:
- The development of the dewars was coincident with a transition in the
BCSB
management from Thomas Earnest to Gerry McDermott and John Kuriyan.
- Gerry McDermott confirmed that the idea of the foam was all down to Jon
Spear - thanks again Jon!
I also wanted to say that the foam dewars are routinely used at the ALS
MX beamlines and particles from the foam are not a problem. Maybe this
was an isolated machining incident.
Corie
Smith, Clyde wrote:
I concur with Thomas' comments ... it all depends upon their intended use. We have used
it extensively here at SSRL and have shaped three different large (4+ litre capacity)
dewars for crystal mounting into the SSRL puck and for loading and unloading Uni-pucks in
an adapter cassette for use with the SAM robot system. **Warning, advertising** To new
users of SSRL we "give" you one of the big dewars and a full kit of hardware
for the robot (incluing a cassette) ... so if you want to try it out, become an SSRL user
(that's the advertising part over with!).
Anyway, for these purposes the foam works wonderfully. There is definitely
only minimal icing and it is possible to fill an entire 96 port cassette
without having to change nitrogen ... it's even better if you do this in a fume
hood so that the water vapour which condenses on top of the nitrogen is
continually drawn off and doesn't get a chance to settle (thanks to Eddie Snell
for that little idea ... but this is another story).
However for freezing crystals, I still prefer the small open glass vacuum
dewars because, as some noted, you can see what is going on much easier ...
although you do get considerable icing unless (again per Eddie Snell) you do it
in a fume hood. I have used a small foam dewar for this in the past and I have
to say icing is not a problem and I din't need to change the N2, just top it up
occassionally.
If they really do cost $160, your best bet might be to email your friendly
local synchrotron group and ask if they will make you something at a fraction
of the price ...
Clyde
---------------------
Clyde A. Smith, Ph.D.
Staff Scientist
Stanford University
Stanford Synchrotron Radiation Lab, MS 99
2575 Sand Hill Rd
Menlo Park, CA 94025 USA
ph (650)926-8544
fax (650)926-3292
cell (650)714-6001
smb.slac.stanford.edu
-----Original Message-----
From: CCP4 bulletin board on behalf of Thomas Earnest
Sent: Thu 9/10/2008 4:07 AM
To: CCP4BB@JISCMAIL.AC.UK
Subject: Re: [ccp4bb] foam dewar usage ?
Jean-Baptiste,
Since these were conceived and developed by Jon Spear when he was a
member of my
group (at the ALS at the time), I know a bit about these Dewars, their
intended usage, and relative benefits.
When Jon first made them, the beamline users and staff quickly realized
the advantages, they spread around
the ALS, and then to other sources. My guess is that for other beamlines
that have both these and
vacuum-jacketed Dewars, the users prefer these over other options.
As with all things, the advantages and disadvantages must be viewed in
context of what the use is. The
fact that these will not shatter, can be shaped to whatever the needed
dimensions are and pockets can be
machined in to allow for transport pucks, cryo-tools, etc., they cool
and warm rapidly and are inexpensive, are all distinct advantages. Thus
for freezing and manipulating crystals at home or the beamline, they are
excellent and
inexpensive options.
Regarding the two comments that followed your post from Uwe and James:
Uwe: When using Berkeley-style pucks or Unipucks (which replicated the
Berkeley form factor), these
are sufficiently dimensioned, and I believe there is a version that
accommodates the SSRL cassette. If
you want another dimension, I suggest contacting Jon directly and
discuss this with him.
James: I'm not sure why you think that chemical resistance or
autoclaving are relevant to the discussion, as these
are for holding and transporting liquid nitrogen and sample
cryo-transport units. Also they are machined
with a bit more precision than a "carpet knife" would give, and this
eliminates the burrs or other bits that
may tend to flake off, as well as allowing for shaping to need.
- Thomas
Thomas Earnest, Ph.D.
Senior Scientist and Group Leader
Structural Proteomics Development Group
Physical Biosciences Division
MS64R0121
Lawrence Berkeley National Laboratory
Berkeley CA 94720
[EMAIL PROTECTED]
510 486 4603
Jean-Baptiste REISER wrote:
Dear all,
Does anyone in the biocrystallogaphy community use foam dewars for
handly liquid nitrogen and freezing/manipulating frozen protein crystals ?
We are interested in the following dewar package from Hampton Research
:
http://www.hamptonresearch.com/products/ProductDetails.aspx?cid=24&sid=187&pid=559
But before purchasing, we would like to have any comments on the
advantages and drawbacks from people who already tried those dewars.
Thanks in advance for your help and advices.
--
*Dr JEAN-BAPTISTE REISER - Chargé de recherche CNRS*
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*Laboratoire de Cristallographie et Cristallogenèse des Protéines (LCCP)*
*et Partnership for Structural Biology (PSB)*
*Institut de Biologie Structural Jean-Pierre Ebel (IBS) - CNRS - CEA -
UJF*
41, rue Jules Horowitz
38027 Grenoble - France
Phone : +33 (0)4 76 20 94 49
Fax : +33 (0)4 76 20 94 80
E-mail : [EMAIL PROTECTED]
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