Yield shifts

To understand the reaction pathways, the yield shifts for the three examples illustrated in Table III were calculated on a fresh feed basis (Table V). These data show that the predominant reaction is the loss of C + paraffins and olefins. Approximately 2.5 wt 95 C + paraffins plus olefins were lost for a +1.5 Research Octane numoer increase. ZSM 5 is selective to cracking both single branched and linear paraffins, and single branched and linear olefins (9) which have very low Research and Motor Octanes, as illustrated below ... 

Despite the same start-of-cycle temperature, the aging rate is significantly reduced due to the higher-pressure operation. KINPTR predicts that doubling the pressure will triple the cycle length and reduce start-of-cycle C5 + yield to 83.8 vol %. The yield shift results from less favorable aromatization equilibrium. Over the cycle, the C5+ yield drops by 4 vol %. This example clearly illustrates the trade-off between cycle length and yields discussed in Section II. 

The yield shifts for these faujasite-containing catalysts are accompanied by a buildup of high boiling material (650°P+) in the liquid recycle stream. 

The number of atoms sputtered by a single incident ion varies with an ion s individual trajectory. Figure 15 shows the distribution of sputtered particles per incident ion at four different primary energies. As the collision energy increases from 100 to 1000 eV, the most probable yield shifts from 0 to 5 sputtered atoms per ion impact. The computer program, TRIM, mentioned earlier, provides quantitative simulations of both sputtering thresholds and yields. ... 

In order to further shift the PL maximum the Cd precursor was employed additionally at the photochemical treatment of Zno.gCdo.iSe NCs after irradiation in the presence of Zn " and TGA, yielding shift of emission maximum from 425 (Fig. 1) to 440 nm. The synthesized NCs exhibit the PL QY of 20%. It should be noted that further shifting of the PL maximum to even longer wavelengths is possible after repetitive photochemical treatments (for example a stable colloidal solution of NCs with an emission at 460 nm and the PL QE of 16% was obtained after 3 cycles of the treatment). 

Pseudocomponent models are very useful for oil fractionation and blending problems. They can also be used to characterize heavy products in some chemical processes such as ethane cracking. Pseudocomponents are treated as inert in most of the reactor models, but they can be converted or produced in yield-shift reactors (see Section 4.5.1). 

Many solids-handling operations have an effect on the particle size distribution (PSD) of the solid phase. The particle size distribution can also be an important product property. Aspen Plus allows the user to enter a particle size distribution as an attribute of a solid substream. In UniSim Design, the particle size distribution is entered on the PSD Property tab, which appears under worksheet on the stream editor window for any stream that contains a pure or hypothetical solid component. Unit operations such as yield-shift reactor, crusher, screen, cyclone, electrostatic precipitator, and crystallizer can then be set up to modify the particle size distribution, typically by using a conversion function or a particle capture efficiency in each size range. 

Yield reactor RYield Yield-shift Reactor... 

The yield-shift reactor overcomes some of the drawbacks of the other reactor models by allowing the designer to specify a yield pattern. Yield-shift reactors can be used when there is no model of the kinetics, but some laboratory or pilot plant data are available, from which a yield correlation can be established. 

Yield-shift reactors are particularly useful when modeling streams that contain pseudocomponents, solids with a particle size distribution, or processes that form small amounts of many byproducts. These can all be described easily in yield correlations but can be difficult to model with the other reactor types. 

The choice of tear stream can have a significant impact on the rate of convergence. For example, if the process of Figure 4.39 were modeled with a yield-shift reactor, then tearing the flowsheet at stream 5 would probably give faster convergence. Some of the simulation programs automatically identify the best tear stream. 

The spin state of the divalent complex, Fe(II)BLM, has not yet been determined. However, the fact that the C nmr spectrum of the Fe(II) antibiotic complex has many carbon resonance lines missing and others that are broadened (Figure 2b), shows that Fe(II)BLM is paramagnetic. Diamagnetic complexes such as Zn(II)-BLM yield shifted but narrow nmr lines Qi). Thus, the only spin states possible for Fe(II)BLM are S = 1 and S = 2. Magnetic, and Mossbauer measurements are under way to resolve this issue. 

The left side of equation (16.6) is the bond s market price broken into clean price plus accrued interest, as it was in (16.4). In fact, it can be shown that rmu is identical to the initial yield in (16.4), mt. The value of % that results in a stable future bond value is the Macaulay duration. At this point, assuming the existence of only one, parallel yield shift, a change in yield will not impact the future value of the bond. The bond s cash flows are immunized, and the instrument can be used to match a liability existing on that date. 

Numerous spectroscopic probes are used to assess infra- and intermolecular interactions (cf. Ratajcak Orville-Thomas, 1980), of which the magnetic resonance methods give highest resolution. An early demonstration of the NMR-detected substituent effect was published by Gutowsky et al. (1952), which yielded shifts of... 

FIGURE 9. Effect of stochastic dependence of mutation and killing (6 = 1) on a basically linear response pattern Lk,Lm). The yield curves were calculated from equation (58) for mi = 10 and kx = 3.7 X 10" (units)for various values of b. Note that the maximum yield shifts to the right for 6 < 1 but to the left for 6 > 1 [cf. equation (59)]. 

Mutation yields, and in particular the position and magnitude of maximum yields, should be measured as carefully as possible as a means of verifying the apparent pattern of mutation-induction kinetics revealed in mutation-frequency curves. For purely linear mutation induction and exponential survival, the maximum mutant yield occurs at the LD37 dose for other nonlinear kinetic patterns, the position and magnitude of the maximum yield shift in mathematically predictable ways. For any given kinetic pattern of killing and mutation, the ratio of the maximum mutant yields plotted over lethal... 

Figure 16. Observation of Fe-ENDOR for the two [2Fe2S] clusters in quinoline oxidore-ductase (Qor). The top part of the left panel shows the field-swept ESE spectrum with the arrows indicating the principal components of the g-tensors of both clusters (FeSII and FeSI). The sticks mark the field positions for which the ENDOR spectra of Fe-substituted Qor (solid traces) and Fe-Qor (dotted traces) are compared in the bottom part of the left panel. In the high-fi equency part the resonances of the Fe ions of both centers are visible. The resonances of Fe appear only weakly in a narrow field range (ca. 359 mT) at low rf frequencies. The right panel shows the experimental line positions of the Fe resonances (filled squares) and the simulation of the outer lines of the Fe interaction arising from FeSII (open circles, dotted line) and FeSI (open squares, dotted line) for comparison. The data-points were taken from CW difference spectra ( Fe vs. Fe) note that the microwave frequency for this panel is different from that in the left part, yielding shifted magnetic field values for related working points. The swept radiofrequency is denoted Urf...

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