Significant influences

During the last decade several factors have profoundly affected the development of the chemical industry and some of these will continue to have significant influence during the next decade. Let us briefly consider four of these, public concern for the safety of chemicals and chemical operations, developments in electronics and computer technology, the cost of energy, and developments in chemical engineering. 

The astonishing developments of recent years in electronics and computer technology have been rapidly seized on by the chemical industry. Although automatic computer control of chemical plant has been practised for many years in the very large continuously operating plants of the petrochemical sector, miniaturization of computer chips, extension of their capabilities and reduction in their cost have made microprocessors viable for much smaller plants. Computers have been used for logging of data, later analysis of which 

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Since the number of shells can have a significant influence on the capital cost, it would be useful to be able to predict it as a target ahead of design. 

Though the type of processing required is largely dependent upon fluid composition at the wellhead, the equipment employed is significantly influenced by location whether for example the facilities are based on land or offshore, in tropical or arctic environments. Sometimes conditions are such that a process which is difficult or expensive to perform offshore can be exported to the coast and handled much more easily on land. 

User Interface This was seen as particularly important, since it has a significant influence on the acceptance of the system by the ultimate user, the ultrasonic technician. 

Protein adsorption has been studied with a variety of techniques such as ellipsome-try [107,108], ESCA [109], surface forces measurements [102], total internal reflection fluorescence (TIRE) [103,110], electron microscopy [111], and electrokinetic measurement of latex particles [112,113] and capillaries [114], The TIRE technique has recently been adapted to observe surface diffusion [106] and orientation [IIS] in adsorbed layers. These experiments point toward the significant influence of the protein-surface interaction on the adsorption characteristics [105,108,110]. A very important interaction is due to the hydrophobic interaction between parts of the protein and polymeric surfaces [18], although often electrostatic interactions are also influential [ 116]. Protein desorption can be affected by altering the pH [117] or by the introduction of a complexing agent [118]. 

The often-cited Amontons law [101. 102] describes friction in tenns of a friction coefiBcient, which is, a priori, a material constant, independent of contact area or dynamic parameters, such as sliding velocity, temperature or load. We know today that all of these parameters can have a significant influence on the magnitude of the measured friction force, especially in thin-film and boundary-lubricated systems. 

In contrast, investigation of the effect of ligands on the endo-exo selectivity of the Diels-Alder reaction of 3.8c with 3.9 demonstrated that this selectivity is not significantly influenced by the presence of ligands. The effects of ethylenediamine, 2,2 -bipyridine, 1,10-phenanthroline, glycine, L-tryptophan and L-abrine have been studied. The endo-exo ratio observed for the copper(II)-catalysed reaction in the presence of these ligands never deviated more than 2% from the endo-exo ratio of 93-7 obtained for catalysis by copper aquo ion. 

Various geometric coring patterns ki polyurethanes (171,175) and ki latex foam mbber (176) exert significant influences on thek compressive behavior. A good discussion of the effect of cell size and shape on the properties of flexible foams is contained ki References 60 and 156. The effect of open-ceU content is demonstrated ki polyethylene foam (173). 

Consistent with this model, foams exhibit plug flow when forced through a channel or pipe. In the center of the channel the foam flows as a soHd plug, with a constant velocity. AH the shear flow occurs near the waHs, where the yield stress has been exceeded and the foam behaves like a viscous Hquid. At the waH, foams can exhibit waH sHp such that bubbles adjacent to the waH have nonzero velocity. The amount of waH sHp present has a significant influence on the overaH flow rate obtained for a given pressure gradient. 

Degradation or Transformation. Degradation or transformation of a herbicide by soil microbes or by abiotic means has a significant influence not only on the herbicide s fate in the environment but also on the compound s efficacy. Herbicides that are readily degraded by soil microbes or other means may have a reduced environmental impact but may not be efficacious. Consider the phenomenon of herbicide-resistant soils. In these cases, repeated application of a given herbicide has led to a microbial population with an enhanced ability to degrade that herbicide (252,253). This results in a decrease or total loss of the ability of the herbicide to control the weed species in question in a cost-effective manner. 

The phenoxyalkanoic herbicides are acidic in nature and thus subject to some degree of ionization. The extent to which the herbicide ionizes is controlled by the acid dissociation constant (fQ of the herbicide in question and the soil solution pH (238). The leaching potential is significantly influenced by these reactions. 

The temperature of esterification has a significant influence on isomerization rate, which does not proceed above 50% at reaction temperatures below 150°C. In resins produced rapidly by using propylene oxide and mixed phthaUc and maleic anhydrides at 150°C, the polyester polymers, which can be formed almost exclusively in the maleate conformation, show low cross-linking reaction rates with styrene. 

There are three generally recognized classifications for sulfur vulcanization conventional, efficient (EV) cures, and semiefficient (semi-EV) cures. These differ primarily ki the type of sulfur cross-links that form, which ki turn significantly influences the vulcanizate properties (Eig. 8) (21). The term efficient refers to the number of sulfur atoms per cross-link an efficiency factor (E) has been proposed (20). 

Other factors which have a significant influence on process selection iaclude absolute quantity of sulfur present, concentration of various sulfur species, the quantity and concentration of other components ia the stream to be treated, quantity and conditions (temperature and pressure) of the stream to be treated, and, the location-specific environmental regulations governing overall sulfur recovery and allowable sulfur dioxide emissions (3). 

Route of Exposure. As discussed below, the route of uptake may have a significant influence on the metaboHsm and distribution of a material. Differences in route of exposure may influence the amount of material absorbed and its subsequent fate. These differences may be reflected in variation in the nature and magnitude of the toxic effect. 

Formulation. The formulation of a material may have a significant influence on its potential to cause toxic injury. Eor example, solvents may facihtate or retard the penetration and absorption of a chemical, resulting in enhancement or suppression of a toxic response, respectively. 

With vertical zone melting and horizontal zone melting without a gas bubble, simple tube rotation at a constant moderate velocity does not significantly influence 5. In those cases, accelerated cmcible rotation or spin up—spin down could be used (72—75). The tube is spun more rapidly than described above, but not at constant velocity. It may, for example, be spun rapidly, suddenly stopped, spun rapidly, etc, resulting in very vigorous stirring. 

In studies with so-called soft /V-ch1oramines, the following factors were shown to significantly influence antimicrobial activity (1) the aUphatic chain length (2) the degree of chlorination of the N atom and (3) the nature of a positive charge (11). 

Trace elements added to copper exert a significant influence on electrical conductivity. Effects on conductivity vary because of inherent differences ia effective atomic size and valency. The decrease ia conductivity produced by those elements appearing commonly ia copper, at a fixed atomic concentration, rank as follows Zn (least detrimental), Ag, Mg, Al, Ni, Si, Sn, P, Fe (most). Table 12 summarizes these effects. In the absence of chemical or physical interactions, the increase in electrical resistivity is linear with amounts of each element, and the effect of multiatom additions is additive. 

We note that when the second term in the denominator of Eq. (14-64) is small, the liquid holdup in the tower can have a significant influence upon the rate of absorption if an extremely slow chemical reaction is involved. 

Life Cycle The gas turbine life and especially hot section life are significantly influenced by the following parameters ... 

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