Word Finder - coagulation

definition

The precipitation of suspended particles as they increase in size (by any of several physical or chemical processes)

definition

The process by which blood forms solid clots.

definition

Similar solidification of other materials (e.g. of tofu).

The nature of the coagulation is not yet completely understood.

Fibrin, produced from fibrinogen by a ferment, is a jelly-like substance, coagulable by heat, alcohol, &c. The muscle-albumins include " myosin " or paramyosinogen, a globulin, which by coagulation induces rigor mortis, and the closely related " myosinogen " or myogen; myoglobulin and myoalbumin are also found in muscles.

If a certain minimum charge must be collected in order to start coagulation, it will need the conjunction of 6n monovalent, or 3n divalent, to equal the effect of 2n trivalent ions.

There is no feasible method at present known of preventing the inclusion of the resin of the latex with the rubber during coagulation, and although the separation of the resin from the solid caoutchouc by means of solvents is possible, it is not practicable or profitable commercially.

The salts of iron quickly cause coagulation of the blood, and the clot plugs the bleeding vessels.

If the latex is warmed or an acid, an alkali or astringent plant juice is added to it, " coagulation " usually takes place more or less readily, the caoutchouc separating in solid flakes or curds.

The efficacy of heat or of an acid, an alkali or other agent in promoting coagulation depends on the character of the latex, and varies with that obtained from different plants.

When exposed to air the latex gradually undergoes putrefactive changes accompanied by coagulation of the caoutchouc. The addition of a small quantity of ammonia or of formalin to some latices usually has the effect of preserving them for a considerable time.

Some of these colloids dissolve in water or other liquids to form solutions called by Graham hydrosols; Graham named the solids formed by the setting or coagulation of these liquids hydrogels.

It has been compared with that of milk and of blood, which depend essentially on the coagulation or separation in curds of a proteid or albuminous substance, such as takes place when white of egg is warmed.

There is, however, reason to believe that the coagulation of latex into rubber is not mainly of this character.

The globules in the latex are liquid, and the phenomenon of coagulation would seem to consist in the passage of this liquid into solid caoutchouc through the kind of change known as polymerization or condensation, in which a liquid passes into solid without alteration of composition or by condensation with the elimination of the elements of water.

The effect of chemical agents in producing coagulation are in consonance with what is known of other instances of polymeric or condensation changes, whilst the fact that the collection of globules separated by creaming after thorough washing, and therefore removal of all proteid, is susceptible of solidification into caoutchouc by a merely mechanical act such as churning, strongly supports the view that the character of the change is distinct from that of any alteration which may occur in the proteid constituents of the latex.

The point of next importance is the coagulation of the latex so as to produce rubber in the form and of the quality required by the manufacturer.

The coagulated rubber separates as a mass of spongy caoutchouc. If the coagulation has been effected in shallow dishes, the rubber is obtained in a thin cake of similar shape known as a " biscuit."

In order to prevent decomposition of any proteid impurity which may remain incorporated with the rubber, the freshly coagulated rubber is sometimes cured in the smoke of burning wood or a small quantity of an antiseptic such as creosote is added during coagulation.

In two or three minutes coagulation takes place, and the rubber is then exposed to the air on sticks, and allowed to drain for eight days.

The globules in the latex, however, consist more probably of a distinct liquid substance which readily changes into the solid caoutchouc. The coagulation of the latex often originates with the " curding " of the proteids present, and this alteration in the proteid leads to the solidification of the globules into caoutchouc. The latter, however, is probably a distinct effect.

Recent investigations point to the conclusion that the immediate cause of the arrest of vitality, in the first place, and of its destruction, in the second, is the coagulation of certain substances in the protoplasm, and that the latter contains various coagulable matters, which solidify at different temperatures.

And it remains to be seen, how far the death of any form of living matter, at a given temperature, depends on the destruction of its fundamental substance at that heat, and how far death is brought about by the coagulation of merely accessory compounds.

The ferment thus set free brings about the coagulation of the serum, which acts as a protective and temporary scaffolding to the injured tissues.

The second operation is the coagulation of the albumen, and the separation of it with other impurities from the Maceration or Imbibition.

Natural arrest of haemorrhage arises from (I) the coagulation of the blood itself, (2) the diminution of the heart's action as in fainting, (3) changes taking place in the cut vessel causing its retraction and contraction.

Solidification of the first kind may be termed "setting," that of the second "coagulation."

The power of coagulation of colloids shown by electrolytes depends in a curious manner on the chemical valency of the effective ion.

If we assume that a certain minimum electric charge must be brought into contact with a group of colloid particles to produce coagulation, twice as many univalent ions must collect to produce the same effect as a number of divalent ions, and three times as many as an effective number of trivalent ions.

The ordinary surface energy of a two-phase system tends to diminish the area of contact, and thus to help the growth of the larger aggregates required for coagulation.

The function of the electrolyte may be to annul such a natural charge and thus allow the non-electric surface energy to produce coagulation.

But recent experiments have shown that the simple theory of coagulation here outlined needs amplification in certain directions.

Brodie, in ascertaining the physiological properties of nucleo-proteids, found that when they were intravascularly injected into pigmented rabbits, coagulation of the blood resulted, but of the eight albinoes which they used, none clotted.

Pickering showed that the three synthesized colloids of Grimaux in the same way produced coagulation in pigmented animals, but failed to do so in albinoes.

Pickering, still later, showed, in the case of four Norway hares, two of which were injected while in their pigmented or summer coat, and two while in their albino or winter coat, that coagulation occurred in the former cases but not in the latter.

Only about 9% of them thus failed absolutely to manifest any trace of coagulation.

But about 7% showed an exceedingly limited coagulation, in which the clot was colourless and flocculent, and confined to the heart.

The rest gave a typical and more or less wide-spread coagulation.

Moreover, it was found that all the failures of coagulation occurred when the nucleo-proteid used was obtained from pigmented animals.

In the intravascular coagulation experiments above described, all the rabbits were carefully weighed, and the amount of nucleoproteid injected until coagulation occurred was measured.

The media are used either in a fluid or solid condition, the latter being obtained by a process of coagulation, or by the addition of a gelatinizing agent, and are placed in glass tubes or flasks plugged with cotton-wool.

To mention examples, blood serum solidified at a suitable temperature is a highly suitable medium, and various media are made with extract of meat as a basis, with the addition of gelatine or agar as solidifying agents and of non-coagulable proteids (commercial " pep tone ") to make up for proteids lost by coagulation in the preparation.

If disseminated intravascular coagulation is present, the patient should be treated with heparin.

If the wound had been caused earlier, silk-like bloodstains would have appeared because of the effect of blood coagulation.

It forms a feedback loop that uses Protein C and Protein S to slow down the coagulation cascade.

Next, blood coagulation rapidly replaces this unstable platelet plug with a stable fibrin clot.

The skin is opened using cutting diathermy and the subcutaneous tissue using coagulation diathermy.

Vitamin K is essential in the synthesis of at least six of 13 proteins needed for coagulation.

Idiopathic thrombocytopenic purpura (ITP) is a bleeding disorder caused by an abnormally low level of blood platelets, small disc-shaped cells essential to blood clotting (coagulation).

Coagulation, or clotting, is a complex process in which specific proteins found in blood plasma combine with other blood components, including platelets, to form clots and prevent blood loss.

The platelet plug then binds coagulation proteins to form a clot that stops bleeding.

Coagulation tests, including clotting time, will be performed to determine the ability of the child's blood to form a clot.

Clotting factors-Substances in the blood, also known as coagulation factors, that act in sequence to stop bleeding by triggering the formation of a clot.