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* > > ****************************************************************************************** > > *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] > > Web sites : http://www.ibs.fr ; http://psb.esrf.fr > > ****************************************************************************************** >
