the nitrogen liquidates is the gas Diazote cooled in lower part of its point of boiling to 77,36 K (- 195,79°C). It with the appearance of a limpid liquid, from where escape from the white “vapors”.
The Nitrogen liquid, discovered in 1883 by Charles Olszewski and Sigismond Wroblewski, is a cryogenic liquid very running, as well in the field of the Scientific research as in industry, in particular because of its low costs (about 5 euros per liter, less than the liquid Hélium is approximately fifty times).
It is used for example in biological sciences to store or crush biological material at a very cold temperature where the action of the enzymes is strongly inhibited.
One stores it in isothermal bottles reserved for this use. The Vase of Dewar is commonly used in the laboratories to store liquid nitrogen. The excellent insulation of the vase of Dewar results in very slow boiling and the nitrogen remains thus a long time without need for expensive equipment of Réfrigération.
The Azote liquidates is used much in Cryogénie.
In laboratory of biology
One uses liquid nitrogen in the medical field for the treatment of Verrue S, of Tumeur S (Cancer of the skin), the conservation of fabrics, Ovule S, Embryon S or Sperme.
Crushing with liquid nitrogen
The very low temperature of liquid nitrogen prevents the operation of the enzymes suitable for degrade the DNA, the ARN or the proteins which one wishes to extract, until one is able to put of the inhibiters of these enzymes in the middle of the cells, in the powder obtained after crushing.- One can tap a fraction of the bottle with liquid nitrogen in an expanded polystyrene container. This material is a good heat insulator, which prevents that all the nitrogen does not evaporate too quickly.
- One uses a mortar and a rammer out of porcelain, which are able to tolerate the low temperatures. One can use a metal ladle to tap nitrogen and to put it in the mortar.
- At the time of the Crushing, the nitrogen evaporates and one can collect the sample crushed at the time when all the nitrogen evaporated.
For the vegetable samples, one continues to crush as long as a powder green-blanchâtre is not obtained (with the need one adds an minor amount of nitrogen to continue crushing a little).
In the food field
One uses liquid nitrogen for a fast congelation (Surgélation) and the food conservation.
Preparation of ice creams
People such Herve This proposed the use of liquid nitrogen as new means of manufacturing ice creams.
In the industrial field
The liquid nitrogen is used for:- the recycling of metals (distinction ferrous and nonferrous metals),
- the electronic refrigeration in during climatic tests or to cool instruments sensitive to the Background noise of to thermal agitation, the such cameras CCC of the Telescope S in Astronomy,
- the Congelation of the grounds, for the construction of works of public works,
In the field of transport
The liquid nitrogen is a rejection of the manufacture of liquid oxygen and is rather cheap. Some researchers developed the idea of its use as energy source to drive a vehicle by simple relaxation in a cylinder.
Precautions for use
The most important risks are those of the " Burn " by the cold.- In laboratory, it is recommended to carry a closed blouse, pants and shoes, to limit the consequences of the inversion of the containers on the people. Scattered by ground, the nitrogen evaporates quickly. It is not to better go inside not to break by the cold the sole of its shoes.
- One can also carry safety goggles to avoid possible projections in the eyes.
- In the same way, it is better to carry medical Gants (even several pairs ones on the others) to avoid the " brûlures" by the cold, during crushing with liquid nitrogen.
- One will use large insulating gloves rather to handle the samples stored in a cooled tank with liquid nitrogen.
Moreover, it should be made sure that the ventilation of the part where the storage of nitrogen is carried out liquidates is sufficient because the liquid nitrogen, even in an isothermal bottle evaporates and produces a great quantity of gas diazotizes which is able to replace oxygen in the gas mixture of the part. From where risks of Asphyxiation.
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