Chemistry: physical processes – Physical processes – Crystallization
Patent
1988-03-30
1990-04-17
Andrews, Melvyn J.
Chemistry: physical processes
Physical processes
Crystallization
156600, 156DIG62, 156DIG113, 422245, 422248, 530419, B01D 902
Patent
active
049177079
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process, a cell and a device for crystal growth, especially adapted to be employed on board a space vessel.
It is known that one of the methods of studying macromolecular substances consists in forming crystals of said substances and in subjecting said crystals to examinations, particularly spectrographic ones. In order to form such crystals, methods of diffusion through a porous diffusion wall are, inter alia, employed. To that end, in an enclosure is disposed a crucible of which the opening is covered by said wall and which is filled with a liquid mixture of a macromolecular substance to be studied and of a precipitating agent in an insufficient concentration to act, then such a precipitating agent is introduced into said enclosure either in vapour form (the porous wall may in that case merely be a net), or in liquid form (it is in that case question of dialysis and the porous wall is a membrane).
By diffusion through said porous wall, the concentration of the precipitating agent mixed with the macromolecular substance tends to be aligned on that of the precipitating agent contained in the enclosure. Consequently, by varying the concentration of this latter precipitating agent, one can act on the crystallization of said macromolecular substance. Generally, the crucible and the enclosure are at least partially transparent, with the result that an operator can visually follow the development of crystallization.
However, the crystals obtained in terrestrial laboratories by carrying out these diffusion techniques are not perfect, both in quality and in size, particularly due to the phenomena of convexion due to gravity.
In order to overcome this drawback, it would be advantageous to be able to carry out such diffusion techniques on board space vessels, since, in that case, the conditions of weightlessness eliminate these phenomena of convexion. However, an attempt at carrying out the terrestrial methods as such would encounter difficulties, if not impossibilities, due in particular to the conditions of launching space vessels and to the short life duration of certain macromolecular substances (two weeks for proteins for example). For example, taking into account the imperatives and relatively long preparation times for launching a space vessel, the macromolecular substances would be dead before crystallization in space can be attempted.
The present invention has for its principal object a process, cells and a device for crystal growth making it possible to adapt the method of diffusion to use on board a space vessel.
To that end, according to the invention, the process of crystal growth by diffusion, particularly intended to be carried out on board a space vessel and according to which a substance to be crystallized contained in a crucible is brought into presence with a precipitating agent through a diffusion wall obturating said crucible, is noteworthy:
in that, in a first recipient is arranged said crucible containing the substance to be crystallized and obturated by said wall;
in that said first recipient is obturated by a stopper of porous material;
in that, in a second recipient is arranged a porous body;
in that said first and second recipients are brought together so that said porous body and said stopper of porous material are in contact with each other; and
in that said precipitating agent is injected into said porous body of said second recipient.
It is seen that, thanks to the invention, said first recipient may be independent of said second recipient, and may be placed on board the space vessel at the last moment before it is launched. It will further be noted that, after said first and second recipients are brought together, the precipitating agent, before attaining the diffusion wall of the crucible, must pass through the porous body of said second recipient and the stopper of porous material of said first recipient. Consequently, one benefits from a wide diffusion front promoting homogeneity of the mixture and therefore generating good conditions for the for
REFERENCES:
patent: 3788818 (1974-01-01), Madjid
patent: 4263010 (1981-04-01), Randolph
patent: 4755363 (1988-07-01), Fujita et al.
Littke, Walter et al., J. of Crystal Growth, 76 (1986), 663-672.
Auffret Jean-Claude
Bonnet Guy M.
Claramonte Manuel P.
Aerospatiale - Societe Nationale Industrielle
Andrews Melvyn J.
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