Outward

Of course, some processes do not require a reactor, e.g., some oil refinery processes. Here, the design starts with the sepauration system and moves outward to the heat exchanger network and utilities. However, the basic hierarchy prevails. 

Figure 3.5 shows centrifuges in which a cylindrical bowl is rotated to produce the centrifugal force. In Fig. 3.5a, the cylindrical bowl is shown rotating with a feed consisting of a solid-liquid mixture admitted at the center. The feed is immediately thrown outward toward the walls of the container. The particles settle horizontally... 

Having found the best nonintegrated sequence, most designers would then heat integrate. In other words, the total problem is not solved simultaneously but in two steps. Moving outward from the center of the onion (see Fig. 1.6), the separation layer is addressed first, followed by the heat exchanger network layer. 

Cyclones. Cyclones are also primarily used as prefilters. These also were discussed in Chap. 3 and illustrated in Fig. 3.4. The particle-laden gas enters tangentially and spins downward and inward, ultimately leaving the top of the unit. Particles are thrown radially outward to the wall by the centrifugal force and leave at the bottom. 

In centrifugal scruhhers (Fig. 11.26), an attempt is made to increase the relative velocity of particles and droplets by centrifuging the droplets in an outward direction. 

A still different approach to multilayer adsorption considers that there is a potential field at the surface of a solid into which adsorbate molecules fall. The adsorbed layer thus resembles the atmosphere of a planet—it is most compressed at the surface of the solid and decreases in density outward. The general idea is quite old, but was first formalized by Polanyi in about 1914—see Brunauer [34]. As illustrated in Fig. XVII-12, one can draw surfaces of equipo-tential that appear as lines in a cross-sectional view of the surface region. The space between each set of equipotential surfaces corresponds to a definite volume, and there will thus be a relationship between potential U and volume 0. 

Most metal surfaces have the same atomic structure as in the bulk, except that the interlayer spaciugs of the outenuost few atomic layers differ from the bulk values. In other words, entire atomic layers are shifted as a whole in a direction perpendicular to the surface. This is called relaxation, and it can be either inward or outward. Relaxation is usually reported as a percentage of the value of the bulk interlayer spacing. Relaxation does not affect the two-dimensional surface unit cell synuuetry, so surfaces that are purely relaxed have (1 x 1) synuuetry. 

The surface unit cell of a reconstructed surface is usually, but not necessarily, larger than the corresponding bulk-tenuiuated two-dimensional unit cell would be. The LEED pattern is therefore usually the first indication that a recoustnictiou exists. However, certain surfaces, such as GaAs(l 10), have a recoustnictiou with a surface unit cell that is still (1 x i). At the GaAs(l 10) surface, Ga atoms are moved inward perpendicular to the surface, while As atoms are moved outward. 

Figure Bl.24.4. Energy loss components for a projectile that scatters from depth t. The particle loses energy A E- via inelastic collisions with electrons along the inward path. There is energy loss A E in the elastic scattering process at depth t. There is energy lost to melastic collisions A along the outward path. For an incident energy Eq the energy of tlie exiting particle is = q - A iv - AE - A E. ...

AS )) the function to be minimized is exp (-AS p/R)/ [36]. A quantitative expression for AS can be found by noting that the A monomers in an unstrained loop (N > 4) have essentially two possible confonnations, pointing either inwards or outwards. For loops smaller than a critical size the inward ones are in an apolar environment, since the enclosed water no longer has bulk properties, and the outward ones are in polar bulk water hence the electrostatic charges on... 

Fig. l.fi. The van tier Waals (vdw) surface of a molecule corresponds to the outward-facing surfaces of the van der Waak spheres of the atoms. The molecular surface is generated hy rolling a spherical probe (usually of radius 1.4 A to represent a mater molecule) on the van der Wools surface. The molecular surface is consiructed from contact and re-entrant surface elements. The centre of the probe traces out the accessible surface. 

The surface properties of metals are such that the surface tends to relax inwards bu systems described by two-body interactions tend to relax outwards. 

Consider a solid wall section as is shown in Figure 3.4. The following relationships between the components of unit outward normal and tangential vectors are true at all points... 

Model verification provides a common-sense check of results. One quick check is to compare the minimized energy to that of similar proteins. It is also important to examine the structure to ensure that hydrophobic groups point inward and hydrophilic groups point outward. 

Work outward from the point of attachment com paring all the atoms attached to a particular atom before proceeding further along the chain... 

When working outward from the point of attach ment always evaluate substituent atoms one by one never as a group Because oxygen has a higher atomic number than carbon... 

Identify the substituents at the chirality center and rank them in order of decreasing precedence accord mg to the system described in Section 5 4 Precedence IS determined by atomic number working outward from the point of attachment at the chirality center... 

The aldotetroses are the four stereoisomers of 2 3 4 trihydroxybutanal Fischer pro jections are constructed by orienting the molecule m an eclipsed conformation with the aldehyde group at the top The four carbon atoms define the mam chain of the Fischer projection and are arranged vertically Horizontal bonds are directed outward vertical bonds back... 

The 12 hydrogen atoms of cyclohexane do not occupy equivalent positions. In the chair conformation six hydrogen atoms are perpendicular to the average plane of the molecule and six are directed outward from the ring, slightly above or below the molecular plane (see Fig. 1.6). Bonds which are perpendicular to the molecular plane are known as axial bonds, and those which extend outward... 

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