Initiators choice

The secondary reactions are parallel with respect to ethylene oxide but series with respect to monoethanolamine. Monoethanolamine is more valuable than both the di- and triethanolamine. As a first step in the flowsheet synthesis, make an initial choice of reactor which will maximize the production of monoethanolamine relative to di- and triethanolamine. 

Reactor conversion. In Chap. 2 an initial choice was made of reactor type, operating conditions, and conversion. Only in extreme cases would the reactor be operated close to complete conversion. The initial setting for the conversion varies according to whether there are single reactions or multiple reactions producing byproducts and whether reactions are reversible. 

Top-Entering Impellers For vessels less than 1.8 m (6 ft) in diameter, a clamp- or flange-mounted, angular, off-center fluidfoil impeller with no baffles should be the initial choice for meeting a wide range of process requirements (Fig. 18-14). The vessel straight-side-height-to-diameter ratio should be 0.75 to 1.5, and the volume of stirred liqiiid should not exceed 4 m (about 1000 gal). 

Axial-Flow Fluidfoil Impellers For vessel volumes of 4 to 200 m (1000 to 50,000 gal), a turbine mixer mounted coaxiaUy within the vessel with four or more baffles should be the initial choice. Here also the vessel straight-side-height-to-diameter ratio should be 0.75 to 1.5. Four vertical baffles should be fastened perpendicularly to the vessel wall with a gap between baffle and wall equal to Df/24 and a radial baffle width equal to Df/12. 

Once the initial choice of promising separator types is made, representative hquid-solid samples should be obtained for preliminaiy tests. At this point, a detailed test program should be developed, preferably with the advice of a specialist. 

To summarise, unexpected corrosion failures are much more likely to occur by localised attack than by uniform attack (which can easily be detected) and although corrosion handbooks are useful for making initial choices of materials for applications where corrosion is important, critical components must be checked for life-to-fracture in closely controlled experiments resembling the actual environment as nearly as possible. 

A number of modifications to eliminate some less favorable aspects of the Levenberg-Marquardt method were considered by Fletcher. For instance, the arbitrary initial choice of the adjustable parameter A, if poor, can cause an excessive number of evaluations of squared error, before a realistic value is obtained. This is especially noticeable if v, i.e., J R x), is chosen to be small, i.e., v = 2. Another disadvantage of the method is that the reduction of A to v at the start of each iteration may also cause excessive evaluations, especially when V is chosen to be large, i.e., = 10. The... 

Although the initial choice of coating material applied for reasons (b) or (c) may be dictated by the particular properties required, the corrosion behaviour of the composite metal coating/metal substrate system must also be taken into consideration in so far as it may affect the maintenance of the desired properties. Consequently, in all cases where protective metal coatings are used the corrosion performance of both coating and substrate require careful consideration. 

In developing synthetic strategies for macrocycles related to corrins, one initial choice has to be made, i.e. whether to incorporate the direct link between rings A and D or to generate it in the final cyclization step. Examples of both approaches have been reported, but syntheses in which the direct link is formed in the final cyclization are more numerous. The total syntheses of vitamin B12 by Woodward/Eschenmoser and Eschenmoser are prominent examples for the realization of both strategies. 

Much of the market success or failure of a plastic product can be attributed to the initial choice of material. Even though the range of plastics has become large and the levels of their properties so varied that in any proposed application only a few of the many plastics will be suitable. 

Since div ( ) mid div 3 (x) commute with 8(x ) and 3 t (x ) for x0 —x, they have vanishing commutators with the hamiltonian and hence, they are time-independent operators. In fact, their constancy in tame implies that they commute with 3 (x) and S(x) at all times and hence they must be c-number multiples of the unit operator. If these c-numbers are set equal to zero initially, they will remain zero for all times. With this initial choice for div 8(x) and div 3tf(x), the operators S and satisfy all of the Maxwell equations (these now are operator equations ) ... 

This very simple result makes it easy to make an initial choice of a buffer we just select an acid that has a pfC, close to the pH that we require and prepare an equimolar solution with its conjugate base. When we prepare a buffer for pH > 7 we have to remember that the acid is supplied by the salt, that the conjugate base is the base itself, and that the pKa is that of the conjugate acid of the base (and hence related to the pKh of the base by pR l + pKh = p/conjugate acid and base have unequal concentrations—such as those considered in Examples 11.1 and 11.2—are buffers, but they may be less effective than those in which the concentrations are nearly equal (see Section 11.3). Table 11.1 lists some typical buffer systems. 

Ed 37Kcal) are generally regarded as increasing in "slowness" in the direction 1isted, because Ad decreases or Ed increases, or both, their value of b increases in the order shown, all other factors remaining equal. Consequently, we must conclude that slow initiators are more likely to produce unstable R-A s than fast ones. The above conclusions involving Tq and initiator choice have been observed experimentally. 

Calculation of Model. Examination of Figs. 1 and 2 suggest the initial choice of p=l for the autoregression part, and the use of 1st differences, i.e. an ARIMA (1 1 0) model. The potential vs. time data was fit using this model. 

Base the initial choice of analgesic on the severity and type of pain, as well as on the patient s medical condition and concurrent medications. 

Failure to respond to initial therapy after 3 days requires patient reevaluation to consider changing therapy to cover pathogens not treated with the initial choice. Antibiotics traditionally have been given for at least 10 to 14 days, with up to 21 days needed for resolution in some patients.31 Recent data suggest that 5-day treatment courses of some fluoroquinolones and telithromycin are as effective as longer courses in adults with... 

Equation (A-23) allows us to determine k. If the initial choice of velocities satisfies Eq. (A-13) and all subsequent choices satisfy this constraint, then... 

This section is used to introduce the momentum-enhanced hybrid Monte Carlo (MEHMC) method that in principle converges to the canonical distribution. This ad hoc method uses averaged momenta to bias the initial choice of momenta at each step in a hybrid Monte Carlo (HMC) procedure. Because these average momenta are associated with essential degrees of freedom, conformation space is sampled effectively. The relationship of the method to other enhanced sampling algorithms is discussed. 

The initial choice of the rat as the primary species for pharmacokinetic studies arose because of their use in pharmacology and toxicology studies. However, there is now such a large database of information about the relative pharmacokinetics of the same compounds in rats and man that, as described below, useful predictions to man can be made. 

How do we know or decide what terms to put in the spin Hamiltonian This is a question of rather far-reaching importance because, since we look at our biomolecular systems through the framework of the spin Hamiltonian, our initial choice very much determines the quality limits of our final results. In other branches of spectroscopy this is sometimes referred to as a sporting activity. We are guided (one would hope) by a fine balance of intellectual inspection, (bio)chemical intuition, and practical considerations. In a more hypochondriacal vein, one could also call this the Achilles heel of the spectroscopy a wrong choice of the model (the spin Hamiltonian) will not lead to an accurate description of nature represented by the paramagnetic biomolecule. 

Generally, where the anion is poorly solvated in the aqueous phase, there is a greater propensity for the ion-pair to reside in the organic phase and, consequently, the overall effect of the quaternary ammonium catalyst is influenced by the initial choice of counter anion of the catalyst or by the anion that is generated in the... 

Fig. 3.1. Percent Distribution by Age at Initial Choice of Chemistry as a Career...

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