Multiplicative cascade

The two procedures primarily used for continuous nitration are the semicontinuous method developed by Bofors-Nobel Chematur of Sweden and the continuous method of Hercules Powder Co. in the United States. The latter process, which uses a multiple cascade system for nitration and a continuous wringing operation, increases safety, reduces the personnel involved, provides a substantial reduction in pollutants, and increases the uniformity of the product. The cellulose is automatically and continuously fed into the first of a series of pots at a controlled rate. It falls into the slurry of acid and nitrocellulose and is submerged immediately by a turbine-type agitator. The acid is deflvered to the pots from tanks at a rate controlled by appropriate instmmentation based on the desired acid to cellulose ratio. The slurry flows successively by gravity from the first to the last of the nitration vessels through under- and overflow weirs to ensure adequate retention time during nitration. The overflow from the last pot is fully nitrated cellulose. 

Bowden and co-workers demonstrated the utility of such a system in multiple cascade reactions, including the use of an otherwise incompatible combination of a Grubbs catalyst and an osmium dihydroxylation catalyst (Figure 5.2) [34],... 

A number of reactions in the body involve multiple cascading steps in which zymogens are successively trans formed into active enzymes. A classic example is the long chemical cascade in Carbohydrateland, in which adenylate cyclase activation eventually results in phosphorylase activation (fig. 3.2). The sequence of reactions that eventually leads to blood clotting following trauma is another example of such a cascade. 

Fig. 4 The LTCAT model reactor with multiple cascade arc generators. (View this art in color at www.dekker.com.)...

Rueping and Antonchick developed an organocatalytic multiple cascade sequence... 

Scheme 3.51 Multiple cascade sequence leading to tetrahydropyridine...

FIGURE 15.51 Schematic of a multiple-cascade configuration applied for bottoms composition control of a distillation column. 

The bis(l,2-dithiole-3-thione) 78 reacts with DMAD in a multiple cascade process to afford product 79 <04JOC3672>. 

Fig. 1.4 Schematic view of the neurovascular unit or module and some of its components. Circulating blood elements, endothelial cells, astrocytes, extracellular matrix, basal lamina, adjacent neurons, and pericytes. After ischemia, perturbations in neurovascular functional integrity initiate multiple cascades of injury. Upstream signals such as oxidative stress, together with neutrophil and/or platelet interactions with activated endothelium, upregulate MMPs, plasminogen activators, and other pro-...

At the next stage (k = 2) of the multiplicative cascade, the subintervals lo and 7i receive the same treatment as the original unit interval. For example, Iq is split into two intervals /oo = [0, 1/4] and /qi = [1/4, 1/2] of size 2 , and the mass is also fragmented as it was at stage 1. It is easy to see that, for example, Moi = li(Ioi) = moMu with similar relations for the other measures /xoo, fiw and Mh In other words, the measure associated with a given interval is obtained by multiplication of... 

In the multiplicative cascade used to generate the binomial measure, the number of intervals was increased by two at each step. One could easily lift that restriction and consider instead a fixed number b of intervals, larger than two. The resulting, more... 

The potential of an online uranium enrichment monitor for assaying the isotopic ratio in UFg gas at a centrifuge enrichment plant, based on calculations and Monte Carlo modeling, was presented (Smith and Lebrun 2011). The unattended monitor would be located on the high-pressure header pipes that receive the gas flow from multiple cascades. The online monitor is to be equipped with a Nal gamma detector for measurement of the 186 keV line from U. The major uncertainties are due to... 

Cell structure Use of ion exchange membrane, multiple-cascade structure, fixed-bed reactor, fluidized-bed reactor... 

The explanation appears to lie in the accumulation of lattice vacancies at the nucleation sites of the helium bubbles. The average energy of a neutron in the fast reactor is above 100 keV, greatly in excess of the 25 eV or so which is required to displace an atom from a lattice site. Neutron collisions, followed by multiple cascade processes, therefore lead to a high density of vacancies and interstitials. The interstitials have a higher mobility than the vacancies and tend to be more rapidly absorbed at grain boundaries and dislocations, where they lose their identity. The surplus vacancies are then available for the formation of voids at the nucleation centers of the helium produced by the (n, a) reactions. 

Use in Isobenzofuran Synthesis. 1,2,4,5-Tetrazine has also been involved in multiple cascade cycloaddition reactions to generate complex substrates. The reactivity of isobenzofuran was delineated with Cgo (eq 5). Starting from a [4+2] cycloaddition between 19 and 1,2,4,5-tetrazine, intermediate 20 was generated. Next, a retro-[4+2] produced the desired isobenzofuran, which... 

With the exception of a few solution processes such as one used to make ethylene-propylene copolymers, traditional CCC ( Ziegler-Natta ) catalysts, which were used to make all linear polyethylenes until the advent of the metallocene catalysts, have multiple active center types and therefore yield polymers having a moderately broad MWD and CCD. Techniques used to control the distribution include blending, use of mixed catalysts or cocatalysts, and the use of staged batch reactors or multiple, cascaded continuous reactors. These techniques complicated the already poorly-defined MWD due to the heterogeneity of the catalyst, and as a result, the distribution could not be reliably modeled or described using the standard equations presented in Chapter 3. 

Tay, D.H.S. and Ng, D.K.S. (2012) Multiple-cascade automated targeting for synthesis of a gasification-based integrated biorefinery, J. Clean. Prod., 34, 38-48. 

These biomimetic amine-activated mechanisms enable multiple cascade protocols for the synthesis of a large scope of carbohydrate-derived compound classes. 

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