Pitch, defined

Asphalt [8052-42-4] is defined by the American Society for Testing and Materials (ASTM) (1) as a dark brown to black cementitious material in which the predominating constituents are bitumens that occur in nature or are obtained in petroleum processing. Bitumen is a generic term defined by ASTM as a class of black or dark-colored (soHd, semisoHd, or viscous) cementitious substances, natural or manufactured, composed principally of high molecular weight hydrocarbons, of which asphalts, tars, pitches, and asphaltites are typical. 

Basically, two engaging gears are two cylinders of different diameter with teeth machined on their periphery (Fig. 29-82). A gear is defined by its basic diameter (pitch diameter), its width, the number of teeth, and the angle that the teeth make in respec t to the axis. 

Square staggered, often referred to as square rotated—Rotating the square inline pitch 45° no longer gives the shellside fluid clear lanes through the bundle. Tube pitch c is defined as for square inline. 

Figure 7-15 shows plots of Pumping number Nq and Power number Np as functions of Reynolds number Np for a pitched-blade turbine and high-efficiency impeller. Hicks et al. [8] further introduced the scale of agitation, S, as a measure for determining agitation intensity in pitched-blade impellers. The scale of agitation is based on a characteristic velocity, v, defined by... 

An alternative form of the right-handed double helix is A-DNA. A-DNA molecules differ in a number of ways from B-DNA. The pitch, or distance required to complete one helical turn, is different. In B-DNA, it is 3.4 nm, whereas in A-DNA it is 2.46 nm. One turn in A-DNA requires 11 bp to complete. Depending on local sequence, 10 to 10.6 bp define one helical turn in B-form DNA. In A-DNA, the base pairs are no longer nearly perpendicular to the helix axis but instead are tilted 19° with respect to this axis. Successive base pairs occur every 0.23 nm along the axis, as opposed to 0.332 nm in B-DNA. The B-form of DNA is thus longer and thinner than the short, squat A-form, which has its base pairs displaced around, rather than centered on, the helix axis. Figure 12.13 shows the relevant structural characteristics of the A- and B-forms of DNA. (Z-DNA, another form of DNA to be discussed shortly, is also depicted in Figure 12.13.) A comparison of the structural properties of A-, B-, and Z-DNA is summarized in Table 12.1. 

Linear and circular measurements that define gears and are used in their specification and design are center distance, offset, pitch diameter, diametric pitch, axial pitch, base pitch, and axial base pitch, lead, and backlash. 

Figure 5.43 Phase contrast optical micrographs of typical helical structures in chemically defined lipid concentrate system, (a) Low-pitch helical ribbon with pitch angle i r = 11 2°. (b) High-pitch helical ribbons with pitch angle t t = 54 2°. (c) Intermediate-pitch helical ribbons with pitch angle i r = 40.8 3.8°. Reprinted with permission from Ref. 162. Copyright 1999 by the National Academy of Sciences, U.S.A.

FIGURE 7.18 A magnified view of a flexible PMOLED on a PET substrate. The pixel pitch is 317 pm and the active pixel area is defined by each square. 

The sample rack is unique in that it possesses pitch both front to back and side to side. A single robot pick-up point is defined, and an optical (IR) sensor constantly monitors the pick-up point for the presence of a sample. Vials placed in the rack roll down to the pickup point, under the influence of gravity. The rack allows implementation of a novel processing scheme. 

Typical spotted arrays would have 100 to 150-micron (pm) diameter features while photolithographically prepared in situ arrays may have features on the order of 2 to 20 pm. The separation between elements is usually measured in terms of a center-to-center distance, spacing, or pitch. Thus, for a printed array, two adjacent spots in the array, e.g., each at 100-pm spot diameter, might have a center-to-center distance of 150 pm, or the spots would be separated by 50 pm from their edges. The number of spots per square centimeter usually defines the spot density. As an example, an array manufactured by Affymetrix (Santa Clara, CA) at >280,000 elements per... 

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