CCP4 bulletin board <CCP4BB@JISCMAIL.AC.UK> wrote on 07/10/2007 02:07:37 PM:
> Jeroen brings up a good point. Back in the old days, around 5 B. C. > (Before Cryo), we would use a chilled air generator to blow a stream > of cold air along the capillary axis to keep the crystals just above > their freezing point--it made a huge difference in crystal lifetime. > I recall a colleague devising an apparatus from a 50 ml conical > tube. The bottom was cut off and cold air was blown in from the > other end. Windows were cut in either side to allow the beam to pass > & covered in mylar. This way the entire capillary was contained > within the cold tube, so no temperature gradients formed along the > length of the capillary (temp gradient => distillation => dead > crystal). Later, we purchased a very clever goniometer head from > Nonius that had a plastic cylinder attached to goniometer head, with > a swivel, so the hose supplying cold air didn't get tangled during > data collection... > > I've often thought duplicating this apparatus when we encounter cryo > problems, but I'm always stymied when trying to find a cheap and > simple source of cold air. Any bright ideas? > Hi Patrick - Many cryosystems (definitely the Cryojet, and I believe the Cryostream) can be set to run at any temperature between room temp and liquid nitrogen temp. I'm not sure of the temperature stability at temps > 0 C, and you might burn out the heaters prematurely if you do this all the time, but it should work. Then you just need to move the nozzle so it's coaxial with your goniostat's rotation axis, and aim the capillary down the nozzle. You could probably even move the capillary *inside* the cryo nozzle a bit, so only the bit with the crystal is in the free stream. It's not a cheap solution, but you've almost certainly got a cryosystem already... - Matt -- Matthew Franklin , Ph.D. Senior Scientist, ImClone Systems 180 Varick Street, 6th floor New York, NY 10014 phone:(917)606-4116 fax:(212)645-2054 Confidentiality Note: This e-mail, and any attachment to it, contains privileged and confidential information intended only for the use of the individual(s) or entity named on the e-mail. If the reader of this e-mail is not the intended recipient, or the employee or agent responsible for delivering it to the intended recipient, you are hereby notified that reading it is strictly prohibited. If you have received this e-mail in error, please immediately return it to the sender and delete it from your system. Thank you.
