Chief source

The chief sources of this important enzyme are (a) the jack bean (Canavalia ensiformis). (b) the soy (or soja) bean (Glycine hispida). The enzyme is of great value in identifying and estimating urea. The action of urease on urea is specific, the reaction catalysed being ... 

There are numerous misconceptions about the sources of various chemical elements in waste, particularly those that are potential acid formers when the waste is incinerated or mechanically converted and used as a refuse-derived fuel. For example, it is often mistakenly stated that the source of chlorine in waste, hence a potential source of HCl emissions, is poly(vinyl chloride). The relative contents of selected, potentially acid-forming elements in the organic portion of a sample of waste collected from various households in one U.S. East Coast city is given in Table 2 (17). In this city, a chief source of chlorine in the waste is NaCl, probably from food waste. 

The ash content of furnace blacks is normally a few tenths of a percent but in some products may be as high as one percent. The chief sources of ash are the water used to quench the hot black from the reactors during manufacture and for wet pelletizing the black. The hardness of the water, and the amount used determines the ash content of the products. The ash consists principally of the salts and oxides of calcium, magnesium, and sodium and accounts for the basic pH (8—10) commonly found in furnace blacks. In some products potassium, in small amounts, is present in the ash content. Potassium salts are used in most carbon black manufacture to control stmcture and mbber vulcanizate modulus (22). The basic mineral salts and oxides have a slight accelerating effect on the vulcanization reaction in mbber. 

Hardness Calcium, magnesium, barium and strontium salts expressed as CaCOa Chief source of scale in heat exchange equipment, boilers, pipe lines, etc. forms curds with soap interferes wKh dyeing, etc. Softening, distillation, internal boiler water treatment, surface active agents, reverse osmosis, electrodialysis... 

The secondary production of lead begins with the recovery of old scrap from worn-out, damaged, or obsolete products and with new scrap. The chief source of old scrap is lead-acid batteries other sources include cable coverings, pipe, sheet, and other lead-bearing metals. Solder, a tin-based alloy, may be recovered from the processing of circuit boards for use as lead charge. 

The acid potassium or calcium tartrates are found in many plants but the chief source of tartaric acid is the impuie acid potassium salt, which separates out as wine-lees, or argol from grape-juice in process of fermentation. 

Although estimates of their abundances vary considerably, Pd and Pt (approximately 0.015 and 0.01 ppm respectively) are much rarer than Ni. They are generally associated with the other platinum metals and occur either native in placer (i.e. alluvial) deposits or as sulfides or arsenides in Ni, Cu and Fe sulfide ores. Until the 1820s all platinum metals came from South America, but in 1819 the first of a series of rich placer deposits which were to make Russia the chief source of the metals for the next century, was discovered in the Urals. More recently however, the copper-nickel ores in South Africa and Russia (where the Noril sk-Talnakh deposits are well inside the Arctic Circle) have become the major sources, supplemented by supplies from Sudbury. 

About one-third of the copper used is secondary copper (i.e. scrap) but the annual production of new metal is nearly 8 million tonnes, the chief sources (1993) being Chile (22%), the USA (20%), the former Soviet Union (9%), Canada and China (7.5% each) and Zambia (5%). The major use is as an electrical conductor but it is also widely employed in coinage alloys as well as the traditional bronze (Cu plus 7-10% Sn), brass (Cu-Zn), and special alloys such as Monel (Ni-Cu). 

Since the early 1990s the United States has imported more oil than it has produced for its own use. And, as the nuclear option became frozen, coal has become the chief source for gcirerating electricity, which itself accounts for about 35 percent of the energy sector. In 1997, 52 percent of electricity produced in the United States was generated from coal and in other recent years the fraction has approached 56 percent. Since the United States accounts for one—quarter of total world energy usage, the increase in coal use in the United States alone has a significant... 

Where do we find the enormous quantities of carbon and carbon compounds needed to feed this giant industry Let s begin our study of carbon chemistry by taking a look at the chief sources of carbon and carbon compounds. 

The chief source of such energy is the combustion of carbon compounds to C02. You know that man exhales more carbon dioxide than he inhales in the air he breathes. This extra carbon dioxide is one of the products of the oxidation processes by which food is oxidized and energy is liberated. 

The method has been applied to the determination of boron in river water and sewage,16 the chief sources of interference being copper(II) and zinc ions, and anionic detergents. The latter interfere by forming ion-association complexes with ferroin which are extracted by chloroform this property... 

Ni is found in many ores in combination with S, As Sb, the chief sources being the minerals chalcopyrite, pyrrhotite and pentlandite. Ni ores are of two types, sulfide and oxide, the former accounting for two-thirds of the world s consumption. Sulfide ores are refined by flotation and roasting to sintered Ni oxide, and either sold as such or reduced to metal, which is cast into anodes and refined electrolytically or by the carbonyl (Mond) process. Oxide ores are treated by hydrometallurgjcal refining, eg, leaching with ammonia. Much secondary Ni is recovered from scrap (Refs 6 7) 1... 

The chief sources of the paraffins are natural gas and petroleum. Petroleum (also called crude oil ) is a complex mixture of paraffins that can he separated by a process called distillation into fractions according to their boiling range. The C1-C4 paraffins under normal conditions are gases, C5-C17 are liquids, and Cig and higher are solids. Paraffins serve many uses to help mankind. Perhaps most importantly, they are the building blocks from which most of our industrial organic chemicals are manufactured. 

Passing now to the ultra-violet, where apparently in Padoa and Buti-roni s work the group of lines in mercury at 3660 A were the chief source, we are in a region in which the absorption is probably nearly complete... 

Although the Solvay process is still in use in some parts of the world, the chief source of sodium carbonate is the mineral trona, Na2C03 NaHC03 2H20. 

Thus the 13 C neutron source (with a little assistance from 22Ne) in thermally pulsing low- and intermediate-mass stars is well established as the chief source of the main component of s-process nuclides in the Solar System. It is not quite clear, however, whether the r0 parameter is something unique, or just the average over a more-or-less broad distribution of values nor is it clear why a similar s-process pattern is seen in stars that are metal-deficient by factors of up to 100 (see Pagel Tautvaisiene 1997). 

The working of the heart as a pump is the chief source of mechanical energy in the coursing of blood within the circulation system... 

The importance of melt-water to the POC load in alpine lakes is a matter of some debate. It has been argued that direct deposition and the melting of snow that falls onto the frozen surface of a lake are the chief sources of POC transport to a lake [50]. The grounds are that movement by groundwater into the lake is unlikely as POCs likely sorb to soil organic matter, and that, at least for the lake studied, most of the water input by streams does not mix with the rest of the water column before flowing out again. The transport of soil into a lake by erosion is likely not an important process under normal conditions and this is confirmed by differences in... 

The following are the chief sources of ignition and suggestions for reducing the hazard due to them ... 

However, the chief source of chloroform is probably chlorination of naturally formed humic acids, especially in the tropics and subtropics. The World Health Organization has set a limit of 30 fig L-1 as the acceptable chloroform concentration in drinking water. Overzealous use of chlorine to sterilize sewage-plant effluent has also led to major fish kills in rivers. 

Wood ashes.—The ash of wood, not coal, contains about 30 per cent, of potassium carbonate. Prior to the exploitation of the Stassfurt salts about the middle of the nineteenth century, the chief source of potash was wood ashes, and the process is still used in certain localities where wood-fuel is employed and where much waste wood is available—e.g. in some parts of Canada, United States, Russia, Spain, etc. The ash of trees, hedge-cuttings, sawdust, etc., can be made to yield potash.5 In the Caucasus, the sunflower is grown on waste land for the sake of its seed. The stalks, leaves, etc., are a by-product and are burnt the ash is used as a source of potash. Nearly 7000 tons per annum of crude potash from this source were exported from Novorossik in Russia. The residues in the manufacture of olive oil and almond shells are also stated by G. l Abate to be exceptionally rich in potash salts F. W. F. Day claims that the roots of the water hyacinth (eiehornia crassipes) have... 

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