Exudation

It is prepared by the direct nitration of toluene with a mixture of nitric and sulphuric acids. TNT is a very stable, violent and powerful high explosive, but less sensitive to shock and friction than picric acid. It is widely used as a filling for shells, bombs, etc. often mixed with ammonium nitrate and other high explosives. The lower grades of TNT may contain isomers which under hot storage conditions may give rise to exudation. 

Never use unprotected bark corks for an apparatus ih which a carefully dried liquid is to be distilled, etc., as these corks always contain appreciable quantities of water, which is exuded when the cork comes into contact with a hot liquid. Rubber stoppers should therefore be used in these circumstances. 

Benzoic acid had been known for several hundred years by the time of Mitscher lich s experiment Many trees exude resinous materials called balsams when cuts are made m their bark Some of these balsams are very fragrant which once made them highly prized articles of commerce especially when the trees that produced them could be found only m exotic faraway lands Gum benzoin is a balsam obtained from a tree that grows m Java and Sumatra Benzoin is a word derived from the Erench equivalent benjoin which in turn comes from the Arabic luban jawi meaning incense from Java Benzoic acid is itself odorless but can easily be isolated from gum benzoin... 

Extrusion cooking Extrusion process Extrusion processes Extrusions Extrusion technology Exudate gums Exxate 600... 

Plant growth regulators Plant gum exudates Plant layout... 

Humans exude about 90 mg/day of volatile fatty acids ia exhaled breath and perspiration, 80% of which is acetic acid (73). In a confined environment, as much as 15—20 mg/m can accumulate and such concentrations can become serious ia submatines or space capsules. 

Thermal Stability, Piging and Exudation ofMETN Propellants, PubHcation LL 77-29, CPIA, Laurel, Md., 1977. 

Plant Gums. There are a large number of plant gums that find appUcation as fat replacers (Table 4) (see Gums, industrial). Many are dried plant exudates. A good review of plant gums exists, giving sources, uses, and an extensive Ust of references (50). There is also a weU-known text avaUable... 

A wide variety of plant exudates have been used ia foods and medicines for centuries, including acacia, karaya, and ghatti. Plant gums derived from seeds iaclude arabic, guar, locust bean, tamatind, and tara. AH play a role ia fat replacement either singly or ia mixtures. 

Gum Arabic. Gum arabic [9000-01-5] is an exudate of the Acacia tree, found in the Middle East. It dissolves readily in water to produce low viscosity solutions. It is used in confectionery products, bakery toppings, beverages, fro2en dairy products, and dry drink mixes (86). 

The extension of the useful storage life of plant and animal products beyond a few days at room temperature presents a series of complex biochemical, physical, microbial, and economic challenges. Respiratory enzyme systems and other enzymes ia these foods continue to function. Their reaction products can cause off-davors, darkening, and softening. Microbes contaminating the surface of plants or animals can grow ia cell exudates produced by bmises, peeling, or size reduction. Fresh plant and animal tissue can be contaminated by odors, dust, iasects, rodents, and microbes. 

Diarrhea is a common problem that is usually self-limiting and of short duration. Increased accumulations of small intestinal and colonic contents are known to be responsible for producing diarrhea. The former may be caused by increased intestinal secretion which may be enterotoxin-induced, eg, cholera and E. col] or hormone and dmg-induced, eg, caffeine, prostaglandins, and laxatives decreased intestinal absorption because of decreased mucosal surface area, mucosal disease, eg, tropical spme, or osmotic deficiency, eg, disaccharidase or lactase deficiency and rapid transit of contents. An increased accumulation of colonic content may be linked to increased colonic secretion owing to hydroxy fatty acid or bile acids, and exudation, eg, inflammatory bowel disease or amebiasis decreased colonic absorption caused by decreased surface area, mucosal disease, and osmotic factors and rapid transit, eg, irritable bowel syndrome. 

The botanical gums represent a family of polysaccharides obtained from a wide variety of plant sources. They are subdivided into exudate gums, seed gums, and gums obtained by extraction of plant tissue. For a gum to be used in commercial quantities, it must be present in the tissues or be readily extractable in relatively pure form which limits the number of commercial botanical gums. 

Natural gums are exuded in a variety of shapes characteristic of the species of origin. These shapes include the globular shape of gum arable and the flakes or thread-like ribbons of gum tragacanth (36). 

Although many plant gum exudates are known (37,38), only gum arable, ghatti, karaya, and tragacanth have wide industrial use. 

Gum Arabic. Gum arable [9000-01-5] is a dried exudate from a species of the acacia tree found in various tropical and semitropical areas of the world. Most of the commercial gum comes from a single species, Jicacia Senegal. The largest producers are the RepubHc of Sudan and several other West African countries, with over 75% of the world s production coming from the Sudan. The best grade comes from Jicacia Senegal and about 90% of the Sudan s production is from this source the remainder comes Jicacia sejal... 

The acacia trees produce gum arable only under adverse conditions, lack of moisture, poor nutrition, and hot temperatures. Gum arable is produced at wounded surfaces of the acacia trees. The wounds are generally produced deUberately in cultivated trees by stripping bark during the dry season. The gum is collected by hand over a period of several weeks with average yields of 250 grams per tree per year. Cmde exudates are hand sorted and exported before processing and milling to various specifications. 

Gum Karaya. Gum karaya [19000-36-61] or sterculia gum is the dried exudate of the Sterculia urens tree, which is now cultivated in India, the primary producing area. The best quahty gum is collected by tapping the trees during the period April to June with a second collection of lower quahty product later in the year. The gum is allowed to dry on the trees, and the cmde gum is collected and sorted according to color and purity. It is further sorted and processed to powdered gum karaya in the country of use. The quahty of supphes varies greatly (43). 

Gum Ghatti. Gum ghatti [9000-28-61] is an exudate Foxn.xinogeissus latifolia a tree that is found in India and Sri Lanka. The exudations are natural, but yields can be increased by making artificial incisions. The sun-dried gum is classified according to color and impurities and processed by grinding to a fine powder. 

Glucuronomannans. Most glucuronomaimans occur as components of certain plant gums and are characterized by the presence of an 0-(P -D-glucurono-pyranosyl)-(1 2)-D-maimopyranosyl linkage ia the molecule (65). Less complex glucuronomaimans are found in the tissues of bracken Pteridium aquilinum) and in tobacco leaf cells where they may be part of the cultured cell wall (132) and exude into the medium in which the cells are grown (133). 

Carbonaceous limestone contains various types of organic material, such as peat, natural asphalt, and even oil shale (qv), as impurities. Such stone is often black and may exude a fetid odor. 

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