Textiles: ironing or smoothing – Smoothing implements – Stretchers
Patent
1992-07-17
1994-03-15
Crowder, Clifford D.
Textiles: ironing or smoothing
Smoothing implements
Stretchers
3810291, 2041801, D06C 308, B01D 5702, G01N 2726
Patent
active
052937038
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a method for preparing a membrane lined with a layer of a gel and a frame for supporting such a membrane, which frame is designed for the implementation of this method. More particularly, the invention relates to the making up of a gel/membrane assembly which can be used in a technique for separating macromolecules by electrophoresis.
In such a technique a layer of a gel such as agarose or a polyacrylamide and an electric field established between two opposite edges of the layer are used. Samples of macromolecules, for example macromolecules of nucleic acid, to be separated are deposited in wells formed in the gel along one of these two edges of the layer. The assembly is next immersed in a suitable electrophoresis liquid. Under the effect of the electric field, the macromolecules of the samples housed in the wells move towards the opposite edge of the layer, through the gel, at rates which depend notably on their molecular mass, so that at the end of a given time, macromolecules of different molecular masses have traveled different distances into the gel.
The macromolecules thus separated are next transferred, either by fluid entrainment or by means of an electric field applied perpendicular to the gel layer, onto a membrane placed against one face of this layer, with a view to their subsequent hybridization and to their subsequent detection. A method and an electrophoresis device, which are designed for achieving such a controlled migration of macromolecules in a stack of rectangular plates of gel, is described in European Patent Application Publication No. 358,556.
When a membrane is used f or supporting the gel layer, the making-up of the gel/membrane assembly is particularly tricky on account of the fineness and of the lack of stiffness of the membrane used, commonly a thin sheet of nitrocellulose, optionally filled with nylon in order to increase its mechanical strength.
Known frames for supporting such a membrane have the drawback of not enabling this membrane to be held in a plane under uniform tension. Pleats resulting f rom tension defects then form in the membrane. The gel layer which is cast onto a membrane thus pleated has deformations which oppose a steady progression of the macromolecules in the layer and render the result of the migration useless. The elimination of these pleats requires lengthy and fastidious manipulations which are incompatible with the requirements of an automated, or indeed industrial, manufacture.
SUMMARY OF THE INVENTION
The object of the present invention is therefore to provide a method for preparing such a membrane lined with gel and a frame for the implementation of this method, which enable the formation of pleats in the membrane to be prevented.
The object of the present invention is also to provide such a method and such a frame which are compatible with industrial means for making up membranes lined with gel and f or manipulating the frames supporting these membranes.
These objects of the invention are achieved, as well as others which will emerge on reading the present description, with a method f or preparing a membrane lined with a layer of a gel, according to which the membrane is firstly laid flat in a horizontal plane and a gel is then cast onto this membrane, this method being noteworthy in that the membrane is put under tension by a traction exerted between at least two substantially parallel opposite edges of this membrane.
By virtue of this tensioning of the membrane, pleats are eliminated and the gel spreads out as a layer of uniform thickness over the membrane.
For the implementation of this method, the invention provides a frame for supporting the membrane, which comprises at least two bars and means of attaching a membrane to these bars, along two parallel edges of this membrane. The frame is noteworthy in that it comprises means of causing the relative position of the two bars to be varied progressively between a position where the membrane is unstretched
REFERENCES:
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Aksas Salah
Cohen Daniel
Coste Jerome C. D.
Ginot Frederic
Bertin & Cie
Crowder Clifford D.
Izaguirre Ismael
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