Large scale containment

Giorgio, R.J. and Wu, J.J. (1986). Design of large scale containment facilities for recombinant DNA fermentations. Trends in Biotechnology, March, pp. 60-65. 

When the results of the large-scale containment experiments are to be applied to the conditions of a real reactor accident, one cannot ignore the absence of ionizing radiation in these experiments, an effect which is able to influence significantly iodine chemistry and behavior, as was discussed in detail in Section 7.3.3.4.4. 

PETN produced on a large scale contains corresponding amounts of the hexanitrate and octanitrate of these compounds, respectively. 

A very important but rather complex application of surface chemistry is to the separation of various types of solid particles from each other by what is known as flotation. The general method is of enormous importance to the mining industry it permits large-scale and economic processing of crushed ores whereby the desired mineral is separated from the gangue or non-mineral-containing material. Originally applied only to certain sulfide and oxide ores. 

Aluminium is obtained on a large scale by the electrolysis of the oxide, dissolved in fused cryolite The oxide, occurring naturally as bauxite, AI2O3.2H2O, usually contains silica and iron(III) oxide as impurities. These must be removed first, since aluminium, once prepared, cannot be freed of other metals (which will be deposited on electrolysis) by refining it. The crude oxide is dissolved under pressure in caustic soda solution the aluminium oxide and silica dissolve and the ironflll) oxide is left ... 

Dioxin IS carried along when 2 4 5 trichlorophe nol IS converted to 2 4 5 T and enters the environ ment when 2 4 5 T is sprayed on vegetation Typically the amount of dioxin present in 24 5 T is very small Agent Orange a 24 5 T based defoliant used on a large scale in the Vietnam War contained about 2 ppm of dioxin... 

The polymeric products can be made to vary widely in physical properties through controlled variation in the ratios of monomers employed in thek preparation, cross-linking, and control of molecular weight. They share common quaHties of high resistance to chemical and environmental attack, excellent clarity, and attractive strength properties (see Acrylic ester polymers). In addition to acryHc acid itself, methyl, ethyl, butyl, isobutyl, and 2-ethylhexyl acrylates are manufactured on a large scale and are available in better than 98—99% purity (4). They usually contain 10—200 ppm of hydroquinone monomethyl ether as polymerization inhibitor. 

Alcohol Production. Studies to assess the costs of alcohol fuels and to compare the costs to those of conventional fuels contain significant uncertainties. In general, the low cost estimates iadicate that methanol produced on a large scale from low cost natural gas could compete with gasoline when oil prices are around 140/L ( 27/bbl). This comparison does not give methanol any credits for environmental or energy diversification benefits. Ethanol does not become competitive until petroleum prices are much higher. 

This represents the first large-scale appHcation of a fluoroaryl organometaOic. Other silicon-containing aryl fluorides such as pentafluorophenyldimethyl silanes, CgF Si(CH2)2X (X = Cl NH2 N(0211 )2), are offered commercially as Flophemsyl reagents for derivati2ation of sterols in chromatographic analysis (166). 

Large-scale recovery of light oil was commercialized in England, Germany, and the United States toward the end of the nineteenth century (151). Industrial coal-tar production dates from the earliest operation of coal-gas faciUties. The principal bulk commodities derived from coal tar are wood-preserving oils, road tars, industrial pitches, and coke. Naphthalene is obtained from tar oils by crystallization, tar acids are derived by extraction of tar oils with caustic, and tar bases by extraction with sulfuric acid. Coal tars generally contain less than 1% benzene and toluene, and may contain up to 1% xylene. The total U.S. production of BTX from coke-oven operations is insignificant compared to petroleum product consumptions. 

There are large-scale operations using direct-heat resistance furnaces. These are mainly in melting bulk materials where the Hquid material serves as a uniform resistor. The material is contained in a cmcible of fixed dimensions which, coupled with a given resistivity of the material, fixes the total resistance within reasonable limits. The most common appHcation for this type of direct-heat electric resistance furnace is the melting of glass (qv) and arc furnaces for the melting of steel (qv). 

As indicated in Table 4, large-scale recovery of natural gas Hquid (NGL) occurs in relatively few countries. This recovery is almost always associated with the production of ethylene (qv) by thermal cracking. Some propane also is used for cracking, but most of it is used as LPG, which usually contains butanes as well. Propane and ethane also are produced in significant amounts as by-products, along with methane, in various refinery processes, eg, catalytic cracking, cmde distillation, etc (see Petroleum). They either are burned as refinery fuel or are processed to produce LPG and/or cracking feedstock for ethylene production. 

A limited number of rare-earth minerals are mined for large-scale rare-earth production mona2ite, bastnaesite, loparite [12173-83-OJ, xenotime [13817-22-6]. In addition, siace the 1980s rare-earth-containing clays called ionic ore are mined ia China. Table 4 shows the rare-earth composition of typical mineral concentrates. 

Second, in the early 1950s, Hogan and Bank at Phillips Petroleum Company, discovered (3,4) that ethylene could be catalyticaHy polymerized into a sohd plastic under more moderate conditions at a pressure of 3—4 MPa (435—580 psi) and temperature of 70—100°C, with a catalyst containing chromium oxide supported on siUca (Phillips catalysts). PE resins prepared with these catalysts are linear, highly crystalline polymers of a much higher density of 0.960—0.970 g/cnr (as opposed to 0.920—0.930 g/cnf for LDPE). These resins, or HDPE, are currentiy produced on a large scale, (see Olefin polymers, HIGH DENSITY POLYETHYLENE). 

HDPE by itself is a safe plastic material on account of its chemical inertness and lack of toxicity. Consequently, film and containers made from HDPE are used on a large scale in food and dmg packaging. Moreover, HDPE has been used in prosthetic devices including hip and knee joint replacements (122). 

LLDPE by itself does not present any health-related hazard on account of its chemical inertness and low toxicity. Consequently, film, containers, and container Hds made from LLDPE are used on a large scale in food and dmg packaging. Some LLDPE grades produced with unsupported metallocene catalysts have an especially high purity due to high catalyst productivity and a low contamination level of resins with catalyst residue. FDA approved the use of film manufactured from these resins for food contact and for various medical appHcations (80). However, if LLDPE articles contain fillers, processing aids, or colorants, thek health factors must then be judged separately. 

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