RU2401648C1 - Medical device for elimination of diastasis and restoration of integrity of injured peripheral nerve and method of its manufacturing - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: medical device for elimination of diastasis and restoration of integrity of injured peripheral nerve consists of tube from compatible with tissues and absorbable in tissues biomaterial, containing substance, which stimulates post-traumatic regeneration of nerve fibres and diastasis elimination. As tube, medical device contains fragment of bird feather calamus. As substance, stimulating post-traumatic regeneration of nerve fibres and diastasis elimination bird feather calamus contains hydroxylapatite or fluorohydroxylapatite. Method of manufacturing medical device for diastasis elimination and for restoration of injured peripheral nerve restoration consists in the following: bird feather with hole diametre which is 1.5-2.0 mm larger than diametre of injured nerve is selected, from bird feather calamus fragment with length from 5 to 15 cm, correspondingly 1-5 cm larger than injured nerve diastasis, is cut out, thickness of wall of feather calamus is reduced to 0.8-1.0 mm. Calamus fragment is kept for 2-3 days in 10 per cent neutral water formalin solution. After that feather calamus fragment is kept for from 3 to 5 days in water solutions of ethyl alcohol of increasing concentration from 70 to 90%. Feather calamus fragment is kept for from 1 to 2 days in 10% water solution of salicylic acid in order to change its hystostructure. Hydroxylapatite or fluorohydroxylapatite are precipitated on internal and external surface of feather calamus fragment, after which feather calamus fragment is sterilised. Method of manufacturing medical device for elimination of diastasis and restoration of injured peripheral nerve integrity in accordance with the second version consists in the following: bird feather with hole diametre which is 1.5-2 mm larger than diametre of injured nerve is selected, from bird feather calamus fragment with length from 5 to 15 cm, correspondingly 1-5 cm larger than injured nerve diastasis, is cut out. Bird feather calamus fragment is mechanically cleaned outside and inside, boiled in water for 3-4 hours, kept for 3-4 days in 10% neutral formalin solution, kept for 5-7 days in 70% water solution of ethyl alcohol. Hydroxylapatite or fluorohydroxylapatite are precipitated on internal and external surface of bird feather calamus fragment, after which bird feather calamus fragment is sterilised.

EFFECT: inventions ensure making medical device for diastasis elimination and restoration of injured peripheral nerve integrity simpler and cheaper and method of such device manufacturing.

9 cl, 1 dwg

Description

The invention relates to medicine, and more specifically, to the field of restoring the integrity of a damaged peripheral nerve.

Known devices for the restoration of damaged peripheral nerves and methods for their manufacture. At the end of this description is a list of patents and copyright certificates on this topic.

In some inventions related to the field of nerve regeneration, a tube is used in which the ends of the nerve (proximal and distal) are placed on different sides during a nerve repair operation. Then the wound is sutured, and under certain conditions the nerve regeneration process takes place, after which the tube is either removed during the second operation, if it is made of material that does not absorb, or the tube is absorbed in the patient’s body and then the second operation is not needed.

For example, in the USSR copyright certificate for invention No. 1204197 (authors E. Chumasov et al.), An autovein is used as such a tube, but this is associated with additional injury to the patient when a vein fragment is removed from him for use as a tube. In US patent No. 6716625 (Authors Lee, Shu-Tung and others) as a tube uses a specially made tube of collagen, which is capable of resolving over time in the patient’s body.

A collagen tube is also used in the invention described in the patent of the Russian Federation for invention No. 2302262 (authors Spector M., Schlessor L., Geistlich P.). The tube for nerve regeneration is formed from a single sheet of collagen-containing material. It has a smooth outer surface, which therefore prevents the adhesion of loose connective tissue cells to it and acts as a barrier against the penetration of these cells through it. The tube has a soft fibrous inner surface, which is designed to provide nerve regeneration. The manufacture of such a tube begins with the manufacture of one sheet of collagen-containing material, including a mixture of 1-10% collagen type III and 90-99% collagen type I. Then two opposite side edges of this sheet are joined and a tube is obtained from the sheet. This invention is taken as a prototype for the proposed invention on a medical device and method for its manufacture. However, the manufacture of such a collagen tube is a rather complicated and time-consuming process, since it is necessary to create ("weave") such a complex geometric object as a cylinder from collagen fibers. Moreover, it is necessary to observe sufficiently accurate dimensions of the tube, as well as to give the external and internal surfaces of the tube specially specified properties. Such a tube also contains substances that promote nerve regeneration, such as collagen suspensions.

Thus, the technical result of the present invention is the simplification and cheapening of a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve and a method for manufacturing such a device. Accordingly, the treatment method is simplified and cheapened - elimination of diastasis and restoration of the damaged peripheral nerve using the proposed device.

A known method for the treatment of damaged peripheral nerves (RF patent No. 20088825 for a device for the treatment of damaged peripheral nerves, authors Galikeev MF and others). The invention according to the patent of the Russian Federation No. 20088825 is selected for comparison with the method of treatment using the medical device proposed in this application for eliminating diastasis and restoring the integrity of the damaged peripheral nerve. The following is a fragment of text from a patent of the Russian Federation No. 20088825:

“The device is used as follows. Under local anesthesia, a standard cut in the projection of the damaged nerve exposes its segments, the nerve bed located between them is freed from scar tissue. The neuroma of the proximal segment is fixed to the sleeve by sewing with an atraumatic needle with a thread 3 / 0-4 / 0. The distal end of the nerve is freed from scar tissue.

A segment of a large saphenous vein is taken from the patient’s leg operatively according to the size of the diastasis. The ends of the veins are sutured with an atraumatic needle to a neuroma, proximal to the location of the sleeve. The sleeve is inserted into the lumen of the vein, then the distal end of the vein and nerve are similarly fixed. After that, a sterile cerebrospinal fluid of the same patient is taken into the lumen of the vein, taken before surgery, in an amount that causes its expansion, the autograft is injected subcutaneously. The wound is sutured in layers.

After applying a bandage over the scar area, a non-magnetic base made of polyvic is installed, fixed to the skin by means of fastening elements. Using a screw adjustment unit, a traction unit - a magnet is installed in the projection of the sleeve. The device without traction remains until the seams are removed, after which the magnet is dosed (1 mm per day) relative to the non-magnetic base, which leads to the movement and tension of the nerve fixed to the sleeve. Traction is carried out within a half to two months. During this time, the patient is prescribed drugs that improve blood circulation, nerve regeneration, as well as drugs that prevent the formation of scar tissue.

At the second stage of the operation, the ends of the damaged nerve are exposed, freshened and epineural sutures are applied using microsurgical technique. After the operation, a gypsum dressing is applied in a position that is functionally advantageous for approaching the ends of the nerve. Immobilization is carried out within 4-6 weeks.

The method of treating a damaged nerve using special technical means described in RF patent No. 20088825 is significantly complicated, special technical devices are used, a metal sleeve is placed in the patient’s body, it is previously removed from the patient’s body, the autovein is required, repeated surgery is required.

Thus, the technical result of the invention proposed in this application is a significant simplification of the operation itself, which is carried out to create conditions for nerve restoration, reduction of the invasiveness of treatment (it is not necessary to cut an autovena using an incision and re-operation is not necessary).

Getting to the description of the essence of the invention, it is necessary to give a definition of the terms "ochin" and "diastasis", which are used in the further description. Ochin is the hollow lower part of the feather shaft of the bird, diastasis is the difference between the ends of the damaged nerve.

The inventive medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve is that the device consists of a tube of tissue-compatible and absorbable in the tissues biomaterial containing a substance that stimulates post-traumatic regeneration of nerve fibers and the elimination of diastasis, and (further follows distinguishing features) a fragment of the feather of a bird's feather was used as a tube, and as a substance stimulating post-traumatic regeneration of nerve fibers and elimination of diastasis, a fragment of the feather of a bird's feather contains hydroxylapatite or fluorohydroxylapatite.

In addition, the invention - a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve - lies in the fact that in the medical device (the following are the distinguishing features), the inner and outer surfaces of the fragment of the feather of a bird's feather contain hydroxylapatite or fluorohydroxylapatite in the form of nanoparticles.

In addition, the invention - a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve - lies in the fact that in a medical device (the following are the distinguishing features), the feather of a bird's feather is the feather of a sparrow, or chicken, or goose, or ostrich, or any other bird, depending on the size of the internal cavity of the feather's nib needed to place the damaged nerve in it, as well as on the length of the fragment of the feather's nib, which should be greater than the damaged diastasis nerve, and the length of the fragment at the point of the pen is from 5 cm to 15 cm, the diameter of the internal cavity of the point of the pen is from 2-3 mm to 10 mm.

The inventive method for manufacturing a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve is that (following the distinguishing features) a bird feather with a hole diameter of 1.5-2.0 mm larger than the diameter of the damaged nerve is selected, cut out from the outskirts of a bird feather, a fragment having a length of 5 to 15 cm, respectively, 1-5 cm longer than the diastasis of the damaged nerve, reduce the wall thickness of a fragment of the outskirts of a feather to 0.8-1.0 mm, maintain a fragment of the outskirts of a feather for 2-3 days 10 percent a neutral aqueous solution of formalin, withstand a fragment of the feather pen for 3 to 5 days in aqueous solutions of ethyl alcohol of increasing concentration from 70 to 90%, withstand from 1 to 2 days a fragment of the feather of a bird feather in a 10 percent aqueous solution of salicylic acid to change its histostructure hydroxylapatite or fluorohydroxylapatite is precipitated on the inner and outer surfaces of a fragment of a bird’s feather, and then a fragment of the bird’s feather is sterilized.

In addition, the invention - a method of manufacturing a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve - consists in the fact that (following the distinguishing features) a bird feather with a hole diameter of 1.5-2.0 mm larger than the diameter of the damaged one is chosen a nerve; a fragment having a length of 5 to 15 cm, respectively, is greater than the diastasis of the damaged nerve by 1-5 cm, which is cut out from the center of the bird’s feather, the fragment of the bird’s feather is mechanically cleaned from the outside and inside, boiled in water for 3-4 hours, and kept for 3-4 days in a 10 percent neutral aqueous solution of formalin, incubated for 5-7 days in a 70 percent aqueous solution of ethyl alcohol, hydroxylapatite or fluorohydroxylapatite is precipitated on the inner and outer surfaces of the fragment of the bird’s feather, and then the fragment of the bird’s feather is sterilized.

In addition, the essence of the invention on a method of manufacturing a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve is that (the following distinctive features) reduce the wall thickness of the fragment of the pen point to 0.8-1.0 mm by machining.

In addition, the invention - a method of manufacturing a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve - lies in the fact that (the following are the distinguishing features) sterilization of a fragment of the outskirts of a bird feather is carried out by gamma radiation.

In addition, the essence of the invention on a method of manufacturing a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve is that (the following are the distinguishing features) for deposition on the inner and outer surface of the fragment of the bird's feather of hydroxylapatite, the fragment of the bird’s feather is placed in the chamber between a solution of calcium chloride and a solution of ammonium phosphate with a pH of 9-10, moreover, the solutions are buffered with 25% aqueous ammonia, approx. Id magnesium or calcium carbonate with the condition of constant during the process, these substances saturation solution.

In addition, the essence of the invention on a method of manufacturing a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve is that (the following are the distinguishing features) for precipitation on the inner and outer surface of the fragment of the bird's feather of fluorohydroxylapatite, this fragment of the bone is placed in the chamber between the solution calcium chloride and a solution of ammonium phosphate with a pH of 9-10, a solution of sodium fluoride is added to the chamber with ammonium phosphate, and the solutions are buffered 25% With aqueous ammonia, magnesium oxide or calcium carbonate is added to the chamber with calcium chloride under the condition of constant saturation of the solution with these substances during the process.

A medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve (hereinafter referred to as a medical device) and a method for its manufacture will be understood from the following description.

The description is illustrated in the drawing.

The drawing shows a micrograph of the wall of the medical device after completion of processing. The drawing indicates: 1 - keratin plates, 2 - gap space between the plates (micrograph taken with a light microscope with magnification X 400, Van Gieson stain).

The medical device consists of a tube made of a tissue-compatible and absorbable biomaterial in the tissues. The tube contains a substance that stimulates the post-traumatic regeneration of nerve fibers and the elimination of diastasis. A fragment of the edge of a bird's feather was used as a tube. The feather consists of keratin and cystine, which makes it possible to dissolve in the tissues of animals and humans. Feathers of different birds (from sparrow to ostrich) can be applied depending on the length of the diastasis and the thickness of the damaged nerve. Choose a feather with a hole diameter of 1.5-2.0 mm larger than the diameter of the damaged nerve. From the selected pen, a fragment of the pen’s edge is cut out, correspondingly, 1-5 cm longer than the diastasis of the damaged nerve (fragment length is from 5 to 15 cm).

The ochin fragment should be slightly longer than diastasis so that the ends of the nerve can be fixed at the edges of the ochin fragment. The ochine fragment is cleaned and the wall thickness of the ochine fragment is reduced to 0.8-1 mm by, for example, machining the outer surface of the ochine fragment with a scalpel.

The following are examples of the subsequent processing of a fragment of a pen nib.

A fragment of the feather’s feather is incubated for 2-3 days in a 10% formalin solution, while the feather blank is sterilized (its quality is controlled by seeding on various media - microbial colonies should not be sown); then a feather fragment is kept for 3 to 5 days in aqueous solutions of ethyl alcohol of increasing concentration from 70 to 90% (as a result, the pen blank is dehydrated, control is carried out by weighing until several results with a constant weight are obtained), the fragment is kept for 1 to 2 days bird feather in a 10% solution of salicylic acid to change its histostructure (keratin plates are reduced in size and gap spaces are formed between them, control of the modification process pen blanks were carried out using a light microscope).

In another embodiment, the ochine fragment is boiled in water for 3-4 hours, aged for 3-4 days in a 10 percent neutral aqueous solution of formalin, kept for 5-7 days in a 70 percent aqueous solution of ethyl alcohol.

After preliminary preparation of the pen point fragment, hydroxylapatite is introduced onto the inner and outer surfaces of the pen point fragment as a substance stimulating nerve regeneration. To do this, the prepared fragment of the feather of a bird feather is placed in a chamber between a solution of calcium chloride and a solution of ammonium phosphate with a pH of 9-10, the solutions being buffered with 25 percent aqueous ammonia, magnesium oxide or calcium carbonate added to the chamber with calcium chloride under the condition that it is constant during the process saturation of the solution with these substances. As a result, particles (nanoparticles) of hydroxylapatite are deposited on the inner and outer surfaces of the fragments of the pen nib. The process proceeds at room temperature (20 ° C), but not higher than 40 ° C.

Hydroxylapatite crystals are necessary to stimulate cell regeneration. In this case, crystal particles are formed in nanometric sizes in the range of 10-14 nm, which allows them to diffuse into the cell, providing effective regeneration.

In another embodiment, fluorohydroxylapatate is deposited on the inner and outer surfaces of a fragment of a pen nib. To precipitate fluorine hydroxylapatite bird feathers on the inner and outer surfaces of the bird’s feather fragment, the chicken bone fragment is placed in a chamber between a solution of calcium chloride and a solution of ammonium phosphate with a pH of 9-10, a solution of sodium fluoride is added to a chamber with ammonium phosphate, and the solutions are buffered with 25% aqueous ammonia. magnesium oxide or calcium carbonate is added to the chamber with calcium chloride under the condition of constant, during the process, saturation of the solution with these substances.

The introduction of fluoride ion in the composition of hydroxylapatite complicates the procedure for obtaining a medical device, but gives a certain advantage in the formation of a regenerate, because it suppresses the cellular activity of fibroblasts, which creates some “backlog” in the rate of regenerate formation during biodegradation of fluorohydroxylapatite crystals contained in a medical device .

Then the manufactured device is packaged in an airtight tape, sterilized by gamma radiation. The finished product is packed in cardboard boxes, which are stored at room temperature.

The drawing shows a micrograph of the wall of the medical device after completion of processing. The micrograph shows a significant increase in slit spaces (2) between keratin plates (1). A similar change in the histostructure occurs as a result of the technological processing of the native edge of a bird feather. The treatment increases the permeability of the wall of the medical device for biologically active substances, the biodegradation time of the device is reduced, which helps to stimulate angiogenesis in the diastasis zone of the damaged nerve. And this leads to a quick and effective restoration of the nerve fiber (bundle).

A method for eliminating diastasis and restoring the integrity of a damaged peripheral nerve using the invented device will be understood from the following description.

Under local anesthesia (diprivan - 5 mg / kg, rometar - 10 mg / kg), its ends are exposed with a standard incision in the projection of the damaged nerve, the nerve bed located between them is freed from scar tissue. The neuroma is excised, and the proximal end is inserted into the lumen of the medical device on one side to eliminate diastasis and restore the integrity of the damaged peripheral nerve, and the distal end of the nerve is freed from the scar tissue and inserted into the lumen of the medical device to eliminate diastasis and restore the integrity of the damaged peripheral nerve. . The wound is sutured in layers.

A medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve and a method for manufacturing a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve were tested during the experiment during operations to restore damaged nerves in rats.

The experiments were carried out on white purebred sexually mature rats (37 rats were used in total, rat mass - in the range of 180-250 g). Under intraperitoneal anesthesia (Nembutal - 40 mg / kg) after depilation and treatment of the hind limbs with a 5% betadine solution by projection access, the sciatic nerve was exposed on the posterior surface of the thigh. It intersected with the formation of 10.0 mm diastasis. The central and peripheral ends of the crossed nerve were inserted into the lumen of a sterile medical device to eliminate diastasis and restore the integrity of the peripheral nerve to a depth of 5.0-7.0 mm. Epineuria of the ends of the nerve was fixed to the wall of the medical device with surgical polymer glue. Provided hemostasis. Layered stitches were placed on the hip wound.

A complete restoration of the integrity of the sciatic nerve of rats in the diastasis zone occurred within 120 days. Biodegradation of a medical device in rat thigh muscles occurred within 30-35 days due to lysis of keratin plates. Restoration of the resected sciatic nerve fragment was carried out in the lumen of a medical device based on biodegradation of the keratin wall of the device and a filler, hydroxyl or fluorohydroxylapatite. As a result, a regenerate was formed in the lumen of the medication device, consisting of vasoids, few differentiated cells, and neurolemmocytes. The axons regenerated during the biodegradation of the medical device had a wave-like course and a parallel distribution typical of the norm. Axons formed regenerates with numerous neurolemmmocytes: axonneurolemmal complexes, on the basis of which myelin and bezmyelinovye nerve fibers were formed.

Explanation: The sciatic nerve of a rat was used as a model; a diastasis of 10.0 mm was created. In the restored fragment, the number of bezmyelin fibers reached 71%, and myelin fibers - 68% of the number of these fibers in the intact sciatic nerve of white rats. By the 60th day of the experiment, pathological changes in the operated limb regressed, and the movement of animals began to be adaptive. Thresholds of pain sensitivity with mechanical irritation returned to control values. Assessment of functional recovery of the operated limb was carried out according to the following methods:

- static sciatic index (SSI),

- Lead reflex test (SRW).

An early return of these indicators to the initial indicators was noted (60th day). Good post-traumatic regeneration of the sciatic nerve in the diastasis zone was evidenced by the rapid regeneration or complete absence of trophic ulcers on the paws of the operated limbs of experimental animals.

The experiments conducted suggest that the proposed invention can be implemented, given the achievements of modern technology and medicine.

Literature

USSR copyright certificate for invention 1204197

RF patent for invention 2008825

RF patent for invention 2169016

RF patent for invention 2290187

RF patent for invention 2302262

RF application for invention 94028108

U.S. Patent 4,778,467

U.S. Patent 4,963,146

U.S. Patent 5,026,381

U.S. Patent 5,656,605

U.S. Patent 5,837,278

US patent 6716225

U.S. Patent 6,821,946

U.S. Patent 7135040

U.S. Patent 7374760

U.S. Patent Application 20020018799

U.S. Patent Application 20040170664

European Patent EP 0945145

International patent application WO 9310722

International application WO for the invention 9324155

Claims (9)

1. A medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve, consisting of a tube made of tissue compatible and absorbable in the tissues of biomaterial containing a substance that stimulates post-traumatic regeneration of nerve fibers and eliminating diastasis, characterized in that the tube contains a fragment fragment of the bird's feather, and as a substance stimulating the post-traumatic regeneration of nerve fibers and elimination of diastasis Era contains hydroxylapatite or fluorohydroxylapatite. 2. The medical device according to claim 1, characterized in that the inner and outer surfaces of the fragment of the outskirts of a bird feather contain hydroxylapatite or fluorohydroxylapatite in the form of nanoparticles. 3. The medical device according to claim 1, characterized in that the feather of a bird's feather is the feather of a sparrow, or chicken, or a goose, or an ostrich, or any other bird, depending on the size of the internal cavity of the feather's feather, necessary to place the damaged the nerve, as well as from the length of the fragment of the nib of the pen, which should be greater than the diastasis of the damaged nerve, the length of the fragment of the nib of the pen is 5 to 15 cm, the diameter of the internal cavity of the nib of the pen is from 2-3 to 10 mm 4. A method of manufacturing a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve, characterized in that a bird feather with a hole diameter of 1.5-2.0 mm larger than the diameter of the damaged nerve is selected, a fragment having a length from 5 to 15 cm, respectively, 1-5 cm more diastasis of the damaged nerve, reduce the wall thickness of the fragment of the pen’s point to 0.8-1.0 mm, maintain the fragment of the pen’s point for 2-3 days in a 10% neutral aqueous formalin solution, withstand the fragment rank pen 3 to 5 days in water solutions of increasing concentrations of ethanol from 70 to 90% is maintained from 1 to 2 days fragment quill bird feathers in 10% aqueous solution of salicylic acid to change its histological structure; hydroxylapatite or fluorohydroxylapatite is precipitated on the inner and outer surfaces of a fragment of a bird’s feather, and then a fragment of the bird’s feather is sterilized. 5. A method of manufacturing a medical device for eliminating diastasis and restoring the integrity of a damaged peripheral nerve, characterized in that a bird feather with a hole diameter of 1.5-2.0 mm larger than the diameter of the damaged nerve is selected, a fragment having a length from 5 to 15 cm, respectively, more than diastasis of the damaged nerve by 1-5 cm, and the fragment of the feather of a bird's feather is mechanically cleaned externally and internally, boiled in water for 3-4 hours, incubated for 3-4 days in a 10% neutral aqueous formalin solution, yanked ivayut 5-7 days in 70% aqueous solution of ethyl alcohol, is deposited on the internal and external surfaces of the bird fragment quill pen or hydroxylapatite ftorgidroksilapatit and then sterilized fragment avian quill pen. 6. The method according to claim 4 or 5, characterized in that they reduce the wall thickness of the fragment at the edge of the pen to 0.8-1 mm by machining. 7. The method according to claim 4 or 5, characterized in that the sterilization of the fragment on the outside of the bird feather is carried out by gamma radiation. 8. The method according to claim 4 or 5, characterized in that for precipitation on the inner and outer surfaces of the fragment of the outskirts of a bird feather of hydroxylapatite, the fragment of the outskirts of a bird feather is placed in a chamber between a solution of calcium chloride and a solution of ammonium phosphate with a pH of 9-10, and the solutions are buffered 25% aqueous ammonia, magnesium oxide or calcium carbonate is added to the chamber with calcium chloride under the condition that the solution is constant during the process of saturation of these substances. 9. The method according to claim 4 or 5, characterized in that for precipitation on the inner and outer surfaces of a fragment of the outskirts of a bird feather of fluorohydroxylapatite, this outflow is placed in a chamber between a solution of calcium chloride and a solution of ammonium phosphate with a pH of 9-10, in a chamber with ammonium phosphate sodium fluoride solution is added, the solutions being buffered with 25% aqueous ammonia, magnesium oxide or calcium carbonate is added to the chamber with calcium chloride under the condition of constant saturation of the solution with these substances during the process.

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