Refrigeration – Low pressure cold trap process and apparatus
Patent
1994-06-01
1995-08-08
Kilner, Christopher
Refrigeration
Low pressure cold trap process and apparatus
62 511, 62 78, 34 92, 34294, F25D 310, F04B 3708, F26B 506
Patent
active
054388384
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field Of the Invention
The present invention relates to a chamber for freeze-drying by cryosorption, wherein cooling is effected by liquid nitrogen in a Dewar vessel.
2. Description of Related Art
In order to better present fine structures or features of a biological specimen under an optical or electron microscope, especially in the case of histochemical applications, freeze-drying (hereinafter referred to as "FD") of a biological specimen is becoming more widely used. Typically, when a biological specimen is freeze-dried, the specimens are, without any pretreatment, frozen extremely rapidly ("cryofixation") and subsequently dried, preferably in a vacuum at temperatures of around -80.degree. C. (in this connection, c.f. inter alia H. D. Coulter and L. Terracio, Anat. Rec. 187, 477-494, 1960; V. Hanzon and L. H. Hermodsson, Ultrastruct. Res. 4, 332-348, 1960; F. D. Ingram and M. J. Ingram, Scanning Electron Microscopoy, IV, 147-160, 1980; J. G. Linner et al., J. Histochem. Cytochem. 34, 1123-1135, 1986; J. D. Mellor, Fundamentals of Freeze-Drying, Academic Press, London, 1978; H. T. Meryman in H. T. Meryman, Editor, Cryobiology, Academic Press, Sn. 609-663, 1966; K. Neumann, Grundri.beta. der Gefriertrocknung (Outline of Freeze Drying), Musterschmidt Verlag, Gottingen, 1952; and references and publications cited therein).
According to the cited prior art, in most instances, freeze-drying of biological specimens is conducted in systems wherein the vacuum is generated by a two-stage pump system (a rotary prevacuum pump with a diffusion high vacuum pump) or a single stage pump system (a turbomolecular pump), and the external cooling of the biological specimens and condensation surfaces is carried out with liquid nitrogen (hereinafter referred to as "LN.sub.2 "). In addition to the considerable expense of the apparatus and equipment necessary to conduct the freeze-drying of biological specimens in this manner, very high operating costs are also incurred because the majority of commercially available or laboratory systems use over 1 liter of LN.sub.2 per hour and also because even FD of small specimens having a diameter of less than about 1 mm requires an average of approximately 14 days. Moreover, a majority of these systems generate high levels of noise owing to the continuously running rotary pumps and therefore does not permit operation of such FD systems in common areas. Another drawback of these systems stems from the especially high labor costs associated with the need to continuously and frequently refill the LN.sub.2. Attempts at automating the chore of refilling LN.sub.2 have the effect of increasing the capital expenditure to a considerable extent.
Finally, a substantial additional disadvantage of these systems resides in the fact that all rotary pumps and diffusion pumps liberate oil vapors, which are deposited on the cold object surfaces and, as a result of this, alter such surfaces artifactually.
Accordingly, repeated attempts were made to use cryosorption systems for the generation of a clean oil-free high vacuum (in this connection, c.f., inter alia German Patent DE 27 39 796 as well as L. Edelmann, Microscopy, Vienna, 35, 31-36, 1979; L. Edelmann, Scanning Electron Microscopy, IV, 1377-1356, 1986; and further literature references cited therein). The system developed and used by Edelmann comprises a divisible cylindrical container with a volume of approximately 0.5 liter, which is connected in a vacuum-tight manner to a tube, the free end of which is equipped with a valve and a hose connection. In the lower part of the container there is a molecular screen as a drying agent. A thermostatically heatable tray to receive the frozen specimens is secured in the upper part of the container. After filling of the molecular screen and loading of the specimen tray with the frozen specimens, both parts are screwed to one another in a vacuum-tight manner. Thereafter, the container is introduced into an LN.sub.2 -filled Dewar vessel. At this point, all of the wall surfaces of
REFERENCES:
patent: 2465229 (1949-03-01), Hipple, Jr.
patent: 3009258 (1961-11-01), Taylor
patent: 3216207 (1965-11-01), Boyer et al.
patent: 3309844 (1967-03-01), Hemstreet et al.
patent: 3330125 (1967-07-01), Klipping
patent: 3668881 (1972-06-01), Thibault et al.
patent: 4232453 (1980-11-01), 34
patent: 4306425 (1981-12-01), Sitte et al.
patent: 4799361 (1989-01-01), Linner
patent: 4976111 (1990-12-01), Larin
patent: 5014517 (1991-05-01), Larin et al.
Coulter et al., "Preparation of Biological Tissues for Electron Microscopy by Freeze-drying", 1960, pp. 477-494.
Ingram et al., "Freeze-Dried, Plastic-Embedded Tissue Preparation: A Review", Scanning Electron Microscopy, IV, 1980, pp. 147-160.
Linner et al., "Cryopreparation of Tissue for Electron Microscopy", 1986, pp. 1123-1135.
J. G. Mellor, "Fundamentals of Freeze-Drying", Academic Press, 1978.
H. T. Meryman, "Cryobiology", Academic Press, 1966, pp. 609-663.
K. Neumann, "Grundrisse der Gefriertroknung", Musterschmidt-Verlag, Goettingen, 1952.
L. Edelmann, "Freeze-Drying of chemically Unfixed Biological Material for Electron Microscopy", Mikroskopie, Vienna, 1979, 35, 31-36.
L. Edelmann, "Freeze-Dried Embedded Specimens for Biological Microanalysis", Scanning Electron Microscopy, 1986, 1337-1356.
Carlemalm et al., "Low Temperature Embedding", Science of Biological Specimen Preparation, 1986, pp. 147-154.
Edelmann Ludwig
Haessig Helmut
Kleber Heinrich
Neumann Klaus
Sitte Hellmuth
Kilner Christopher
Leica AG
LandOfFree
Chamber for freeze-drying by cryosorption does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Chamber for freeze-drying by cryosorption, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Chamber for freeze-drying by cryosorption will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-964739