Principal Characteristics

1 Principal Characteristics. - Molecular sieves with pore openings of about 0.45 nm show very interesting shape-selectivity properties for the conversion of methanol to olefins (MTO process). The small-pore molecular sieves studied in the MTO process are chabazite, erionite, zeolite T, ZK-5, ZSM-34, zeolite A, SAPO-17, SAPO-34, and SAPO-44. All of them can sorb only straight chain molecules, e.g. primary alcohols and linear paraffins and olefins, but no branched isomers and aromatics the pore opening is smaller than the kinetic diameter of branched and aromatic molecules, but large enough to permit the access of linear molecules. 

The pore openings of small-pore molecular sieves are 8-membered oxygen rings. The dimensions vary with the shape of the rings, but the effective size is always lower than 0.45 nm. The ring shape may be circular or puckered and elliptical (see Table 1). 

The porous systems of small-pore molecular sieves are conformed by ellipsoidal or spherical cavities that share the 8-membered oxygen rings to generate a three-dimensional channel system. These 

Ncune Ring shape Pore size Cavity shape Cavity size 

8-rings. The three-dimensional porous structure is originated by the linkage of the large cavities through the 8-rings. 

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We will limit the principal characteristics to the following items ... 

The principal characteristics of bitumen are its softening point and its needle penetrability. In France the latter has always been the basis for bitumen classification and class designation. Yet, the former is more representative of a bitumen s capacity to deform when the service temperature increases. The other properties have more or less importance depending on the application. 

Appendix 1 comprises a series of tables giving the principal characteristics of pure components most commonly found in the petroleum industry and supplying data for calculation of some useful properties. 

The principal characteristics of clean wool types ate average diameter, measured in micrometers, and average length, measured in millimeters (Table 3). 

The overall objective of research under way as of ca 1997 is to develop a system of sale by description for fine and medium wools whereby the buyer is presented only with measured data on the principal characteristics of the raw wool, as well as an assessment of the less important characteristics by an independent skilled appraiser (8). A scheme for assessing the risk of the presence of colored fiber content in greasy wool has been proposed which depends on production parameters and on the age and sex of the sheep (5). Instmmentation and computer algorithms for the measurement of style and handle... 

There is a gradual transition from particulate setthug into the zone-settling regime, where the particles are constrained to settle as a mass. The principal characteristic of this zone is that the setthug rate of the mass, as observed in batch tests, will be a function of its solids concentration (for any particular condition of flocculation, particle density, etc.). 

Until Jenike developed the rationale for storage-vessel design, a common criterion was to measure the angle of repose, use this value as the hopper angle, and then fit the bin to whatever space was available. Too often, bins were designed from an architectural or structural-engineering viewpoint rather than from the role they were to play in a process. Economy of space is certainly one vahd criterion in bin design, but others must be considered equally as well. Table 21-14 compares the principal characteristics of mass-flow and funnel-flow bins. 

TABLE 21-14 Principal Characteristics of Mass-Flow and Funnel-Flow Bins ... 

Substitution (see Seetion 1.02.9.1.1) is the formal proeedure most widely applied in modifying parent names. Indeed, the general term substitutive nomenclature is often used to describe the system of nomenclature in which substitution is the main operation. A fundamental concept of this system is that of the principal characteristic group . 

For nomenclature purposes, substituents can be divided into those that are always cited as prefixes (e.g. chloro-, alkoxy-) and those which can be cited as either prefixes or suffixes e.g. oxo-/-one, carbamoyl-/-carboxamide). If any of the latter are present, the name will normally contain a suffix. However, only one kind of group can be cited as suffix, and this is chosen according to a strict order of priorities. The group thus selected is known as the principal characteristic group . 

It is clear that tire rate of growdr of a reaction product depends upon two principal characteristics. The first of these is the thermodynamic properties of the phases which are involved in the reaction since these determine the driving force for the reaction. The second is the transport properties such as atomic and electron diffusion, as well as thermal conduction, all of which determine the mobilities of particles during the reaction within the product phase. 

Table 25.11 Principal characteristics of the polyarylate Arylef UlOO...

The various studies of shock-modified powders provide clear indications of the principal characteristics of shock modification. The picture is one in which the powders have been extensively plastically deformed and defect levels are extraordinarily large. The extreme nature of the plastic deformation in these brittle materials is clearly evident in the optical microscopy of spherical alumina [85B01]. In these defect states their solid state reactivities would be expected to achieve values as large as possible in their particular morphologies greatly enhanced solid state reactivity is to be expected. 

The principal characteristics of the naturally occurring members of the lobeline group (see also Table A, p. 23) are as follows —... 

In addition to tlie exponential and Weibull distributions, several otlier probability distributions figure prominently in reliability calculations and hazard risk analysis. Presented below are tlieir pdfs, principal characteristics, and an indication of their application. 

Table 1. Principal characteristics of the polymer fractions used...

The principal characteristic of a particle which determines the dominant suspension mechanism is its terminal falling velocity. Particles with low falling velocities will be readily suspended by the action of the eddies, whereas the dispersive forces will be most important with particles of high falling velocities. In a particular case, of course, the fluid velocity will also be an important factor, full suspension of a given particle occurring more readily at high velocities. 

There are two principal characteristics of turbulence. One is the scale which is a measure of the mean size of the eddies, and the other is the intensity which is a function... 

From a physical point of view, the finite difference method is mostly based based on the further replacement of a continuous medium by its discrete model. Adopting those ideas, it is natural to require that the principal characteristics of a physical process should be in full force. Such characteristics are certainly conservation laws. Difference schemes, which express various conservation laws on grids, are said to be conservative or divergent. For conservative schemes the relevant conservative laws in the entire grid domain (integral conservative laws) do follow as an algebraic corollary to difference equations. 

According to the authors mentioned above, induced chain reactions (Livingston ) or induced catalysis (Bray and Ramsey ) take place when the very slow reaction between the acceptor and actor is catalyzed by the inductor. However, since the chemical characters of the acceptor and the inductor are the same, the actor reacts with the inductor, too, thus a part of it will be excluded from the catalysis. The principal characteristics of reactions of this type according to Luther and Schilow are that the value of Fj largely exceeds 2 and that the plot of Fj rm 5([Ac]/[I])o rises exponentially. 

The principal characteristic of induced reactions of this type which have not been stressed so far, is that the extent of the induced change greatly decreases and in most cases reaction even ceases in the presence of chain-breaking substances. The induced reaction can be suppressed by any substances reacting with chain carriers at a higher rate than does the acceptor, and the product of the reaction of the suppressor can easily react with the inductor. Since the concentration of the chain carriers is generally low, the supressors of induced chain reactions exert considerable effect even in small quantity. The effect is particularly pronounced when the suppressor reacts reversibly. 

It is possible to show that the complexity distribution retains all of the principal characteristics of the distribution for the condensation of A—R—B/ i alone (Fig. 66). Indeed, these are already present in Eq. (30). The major difference has to do with the presence of linear... 

Table 1 Principal characteristics of Qwasi model (based on [34])...

Principal characteristics Impact categories Exposure routes Fate, exposure and effect... 

As summary, the principal characteristics of the Qwasi model are listed in Table 1. 

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