Refrigeration – Cooled enclosure – Portable receptacle
Reexamination Certificate
2001-12-03
2004-03-09
Jones, Melvin (Department: 3744)
Refrigeration
Cooled enclosure
Portable receptacle
C062S371000
Reexamination Certificate
active
06701743
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to the field of x-ray diffraction and, more specifically, to the mounting of cryogenically cooled crystallography samples on an x-ray diffraction goniometer.
BACKGROUND OF THE INVENTION
In recent years, it has become common to use x-ray diffraction for the structural determination of biological macromolecules (proteins). To protect the protein crystals from radiation damage, it is desirable to cool them to cryogenic temperatures. This is typically accomplished by storing them in a liquid nitrogen dewar and then transferring them onto a goniometer equipped with a device which cools the sample during the measurements by blowing cold nitrogen (or helium) gas onto the sample. However, of course, the samples must be maintained at cryogenic temperatures while they are transferred from the storage dewar onto the goniometer. To transfer the samples to the goniometer, cryogenic transfer vials have been used. An example of a typical prior art vial is shown in FIG.
1
.
The prior art sample vial
10
consists of an outer container
12
, typically made of a plastic material, and a magnetic base
14
. Attached to the base
14
is a sample holder that extends into the vial
10
, and includes a fastener
18
at the end that holds a crystal sample
20
in place. In the preferred embodiment, the fastener is a surgical nylon loop (10-20 &mgr;m), but also may take other forms. As shown in the figure, the base/sample holder combination has a shape and size that allows it to form a seal with the container
12
, with the sample holder projecting into the container interior. In order to maintain the sample at cryogenic temperatures, the container is filled with a cryogen
22
, typically liquid nitrogen. The vial is vented to allow the escape of boiled-off cryogen. This cryogen maintains the crystal at a sufficiently low temperature, but causes difficulties in practice. The standard goniometer receives the magnetic base
14
of the vial, but is located such that the sample holder
16
projects outward at a horizontal angle. Thus, as the container
12
is removed from the base, much or all of the cryogen spills out and is lost. Once the cryogen is lost, the sample crystal will rapidly warm up towards room temperature and can be damaged. It is possible also to remove the base from the upright container with a hand tool such as “cryotongs.” In this case, there is no cryogen used. Rather the cryotongs are cooled to liquid nitrogen temperatures and the thermal mass of the cryotong head keeps the sample cold during the transfer process.
However, to remove the base in this manner and successfully transfer it to the goniometer requires an inordinate degree of quickness and dexterity, and makes the process more difficult and subject to failure. There are also a limited number of “inverted sample” goniometers in service that can be used to position the base so that the sample holder faces downward. This allows the container
12
to be removed without spilling the cryogen. However, such goniometers have drawbacks including higher cost, less geometric access to the sample and less flexibility in orienting the sample, and thus the use of this solution is limited in practice.
SUMMARY OF THE INVENTION
In accordance with the present invention a cryogenic transfer vial is provided for use with a crystal sample material and allows transfer of a sample holder to a goniometer without spilling of a cryogen in the vial, such as liquid nitrogen. The vial includes an outer container surface within which the sample material is enclosed. A container lid that seals to the outer surface also serves as a base, typically magnetic, for a sample support to which the sample material is attached. With the lid in place on the vial, the sample support extends into the vial, such that the sample material is suspended at a sample location within. Within the container outer surface is a cryogen retainer that surrounds the sample location and that retains the cryogen in that region, particularly against the force of gravity. The retainer prevents any significant spillage of the cryogen if the transfer vial is inverted and opened, such as during placement of the sample support lid in a goniometer, and removal of the outer container.
In one embodiment of the invention, the cryogen retainer is an adsorptive material located within the outer container surface. The adsorptive quality of the material easily holds the cryogen in place, even if the vial is inverted. Such a material may be, for example, a carbon foam that fills a portion of the vial, but not the sample location. The foam may be below the sample in the vial, and may also partially surround it. In another embodiment, the retainer may be a baffle that, in conjunction with the outer surface, forms a region surrounding the sample location within which the cryogen is contained. The surrounding region is vented, and may have an opening at an end away from the container lid. This would allow for filling of the vial with cryogen, while still ensuring that the majority of the cryogen is retained when the vial is open and inverted.
REFERENCES:
patent: 5321955 (1994-06-01), Leonard
patent: 5419143 (1995-05-01), Leonard et al.
patent: 5632151 (1997-05-01), Baker et al.
patent: 6119465 (2000-09-01), Mullens et al.
patent: 000172101 (1986-02-01), None
Durst Roger D.
Foundling Stephen I.
He Bob Baoping
Li Max
Bruker AXS Inc.
Jones Melvin
Kudirka & Jobse LLP
LandOfFree
Non-spilling cryogenic transfer vial for crystal sample... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Non-spilling cryogenic transfer vial for crystal sample..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-spilling cryogenic transfer vial for crystal sample... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3276793