Use classifications

Wa.ter Qua.litySta.nda.rds, The first step in water quahty standards is stream use classification. The individual states must decide what the uses of their water will be. The four categories, as defined by the EPA, are Class A, primary water contact recreation Class B, propagation of desirable aquatic life Class C, pubHc water suppHes prior to treatment and Class D, agricultural and industrial uses. States may vary the definition of these classes to meet their own needs. The second step is to develop water-quaHty criteria. This is the specific concentration of a pollutant that is allowable for the designated use. 

The uses of steel are too diverse to be Hsted completely or to serve as a basis of classification. Inasmuch as grades of steel are produced by more than one process, classification by method of manufacture is not advantageous. The most useful classification is by chemical composition into the large groups of carbon steels, alloy steels, and stainless steels. Within these groups are many subdivisions based on chemical composition, physical or mechanical properties, or uses. 

One useful classification of graphite depends on the mode of formation that leads to three physically distinct common varieties dake, lump, and amorphous. The term dake is self-explanatory dake forms occur disseminated in rock. Lump graphite occurs in fissure-filled veins in pegmatite dikes, also associated with chip and the rarer needle forms. Amorphous graphite occurs in beds that were once coal, but fine-grained, easily ground vein graphite is also classified as amorphous. 

Glassification. Classification (2,12,26,28) or elutriation processes separate particles by the differences in how they settle in a Hquid or moving gas stream. Classification can be used to eliminate fine or coarse particles, or to produce a narrow particle size distribution powder. Classification by sedimentation iavolves particle settling in a Hquid for a predetermined time to achieve the desired particle size and size distribution or cut. Below - 10 fim, where interparticle forces can be significant, gravitational-induced separation becomes inefficient, and cyclone and centrifugation techniques must be used. Classification also separates particles by density and shape. Raw material separation by differential sedimentation is commonly used in mineral processiag. 

Dental abrasives can be classified either according to their use or according to the degree of their abiUty to abrade (see Dentifrices). The use classification, adopted for the ADA specification no. 37 for powdered dental abrasive materials, is based on removal of stain from natural teeth or on restorations of all types. Several abrasives are used in dentistry in a variety of grit sizes and shapes. 

A useful classification of sensitizing dyes is the one adopted to describe patents in image technology. In Table 1, the Image Technology Patent Information System (ITPAIS), dye classes and representative patent citations from the ITPAIS file are Hsted as a function of significant dye class. From these citations it is clear that preferred sensitizers for silver haUdes are polymethine dyes (cyanine, merocyanine, etc), whereas other semiconductors have more evenly distributed citations. Zinc oxide, for example, is frequendy sensitized by xanthene dyes (qv) or triarylmethane dyes (see Triphenylmethane and related dyes) as well as cyanines and merocyanines (see Cyanine dyes). 

A useful classification of lands of reaclors is in terms of their concentration distributions. The concentration profiles of certain limiting cases are illustrated in Fig. 7-3 namely, of batch reactors, continuously stirred tanks, and tubular flow reactors. Basic types of flow reactors are illustrated in Fig. 7-4. Many others, employing granular catalysts and for multiphase reactions, are illustratea throughout Sec. 23. The present material deals with the sizes, performances and heat effects of these ideal types. They afford standards of comparison. 

Diying equipment may be classified in several ways. The two most useful classifications are based on (1) the method of transferring heat to the wet solids or (2) the handling characteristics and physical properties of the wet material. The first method of classification revels differences in diyer design and operation, while the second method is... 

Completion of product is different to rework as rework implies that something was carried out incorrectly whereas returning product for completion implies that something was not done at all. This minor distinction can be a useful classification in subsequent analyses. 

Median Lethal Dose (LD) The statistically derived single dose of a chemical that can be c.xpected to cause death in 50% of a given population of organisms under a defined set of experimental conditions. This figure has often been used to classify and compare toxicity among chemicals but its value for this purpose is doubtful. One commonly used classification of this kind is as follows ... 

The great variations among solids make it desirable to And useful classification schemes. Though this topic is taken up much later in the course (Chapter 17), a beginning is provided by a look at the electrical conductivity of solids. 

A frequently used classification is based on the degree of substitution and types of side groups for characterization (Ebringerova, 2005 Sedlmeyer, 2011) ... 

The concept of hard and soft acids and bases ( HSAB ) should also be mentioned here. This is not a new theory of acids and bases but represents a useful classification of Lewis acids and bases from the point of view of their reactivity, as introduced by R. G. Pearson. 

The hardness of any solid can be assessed with testing equipment that measures the relative ease with which a surface can be either scratched or penetrated by another solid of known hardness. A long-used classification of the hardness of minerals, the Mohs scale of hardness, is based on the scratch test ten rather common minerals are arranged in the scale in order of their increasing relative hardness and listed in a scale varying from 1 to 10 (see Table 20). Each mineral in the Mohs scale scratches those with lower hardness numbers but does not scratch higher-hardness minerals. If a... 

A much more useful classification of inhibitors can be made on the basis of the mechanisms by which they act. Competitive inhibitors combine, with the enzyme at the same site as the substrate does, thus blocking the first step in the sequence. Noncompetitive inhibitors combine with the enzyme at some other site to give a complex that can still combine with the substrate, but the resultant ternary complex is unreactive. Uncompetitive inhibition results when the inhibitor and substrate combine with enzyme forms as in the following mechanism. 

Another useful classification technique that makes use of two different bench-type experiments (i.e., permeability and deaeration) has been presented by Mainwaring and Reed (1987). The above three classifications are described in the following sections. 

Fig. 3 Land use classification based on the information for the year 1984 at 1 100,000 scale. Legend refers to the classification reported in Table 1...

Table 1 Land use classification adopted for the hydrological simulations...

The most frequently used classification system is that proposed by Vaughan Williams (Table 6-1). Type la drugs slow conduction velocity, prolong refractoriness, and decrease the automatic properties of sodium-dependent (normal and diseased) conduction tissue. Type la drugs are broad-spectrum antiarrhythmics, being effective for both supraventricular and ventricular arrhythmias. 

Classification also facilitates communication. A classification system represents the development of a common language that allows for consistency in communication. Clinicians can be confident that they are talking about the same thing when they use classification labels for disorders x, y, or z-... 

Various criteria can be applied in order to arrive at a useful classification scheme for the different mechanisms of solute transport through biological membranes. 

In more recent years, Herman Mark has, as we all know, concentrated more on the effects of heterophase morphology of polymers on their mechanical properties. This has enabled him to set up a useful classification system of the various types of heterogeneities which can occur in polymers, e.g., crystallinity, incompatibility, particulate and fibrous inclusions, etc. and to discuss these in the context of their effect on the mechanical properties. Such an "overview" has again kept Mark in great demand as a speaker. 

A widely used classification of petroleum distinguishes between crude oils either on a paraffin base or on an asphalt base and arose because paraffin wax separates from some crude oils on cooling, whereas other oils show no separation of paraffin wax on cooling. The terms paraffin base and asphalt base were introduced and have remained in common use (van Nes and van Westen, 1951). 

In the same way as linear discriminant analysis is the most-used classification method, stepwise selection by LDA (SLDA) is the selection method that shows the greatest number of applications in food chemistry. 

Garzotto M, Beer TM, Hudson RG et al. Improved detection of prostate cancer using classification and regression tree analysis. JCh n Oncol 2005 23 4322 329. 

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