Sequential processing mode

An enzyme is a macromolecule. What behavioral features of this biological macromolecule invest it with catalytic powers It has long been recognized1 3 that the mode of operation of this macromolecule M involves two sequential processes (1) binding of the substrate S and (2) provision of a molecular environment conducive to the chemical transformation ... 

Constant-volume batch diafiltration is the most efficient process mode. Sequential batch diafiltration is a series of dilution-concentration steps. Continuous diafiltration practiced in one or more stages of a cascade system has the same volume turnover relationship for overall recoveries as sequential batch diafiltration. The residence time however is dramatically reduced. If recovery of permeable solids is of primary importance, the permeate from the last stage may be used as diafiltration fluid for the previous stage. This countercurrent diafiltration arrangement results in higher permeate solids at the expense of increased membrane area. 

When there are multiple recycles present, it is sometimes more effective to solve the model in a simultaneous (equation-oriented) mode rather than in a sequential modular mode. If the simulation problem allows simultaneous solution of the equation set, this can be attempted. If the process is known to contain many recycles, then the designer should anticipate convergence problems and should select a process simulation program that can be run in a simultaneous mode. 

To initiate the global simulation, the CHEOPS server as well as the wrappers of all participating simulators are started. Next, the simulation expert specifies the input file for CHEOPS and runs the simulation. CHEOPS solves the simulation in a sequential-modular mode Each simulator is run in turn, where the simulation results are passed from one simulator to the next. In the case of feedback loops, this process is iterated until a steady state is reached (i.e., the global simulation converges). 

Laser pulses of 3 jis duration and a typical fluence of 1.0 J/cm and Infrared absorption cross sections of 10 -10 cm yield photon absorption rates of 10 -10 photons/s, which are much slower than the rate of Intramolecular vibrational energy redistribution In systems such as benzyl anion. Hence, the anions are excited In a sequential process In which the vibrational energy Is redistributed before the next photon Is absorbed. This means that such experiments cannot determine In which vibrational mode(s) the energy resides. 

A flowsheet where the units are solved sequentially is ideal from computational view point. However, most of the process plants involve recycles, particularly those highly integrated. In Sequential-Modular mode, there are four methodological issues ... 

In the present work it has been shown that on-line coupling of flowthrough fractionation in RCC with ICP-EAS detection enables not only the fast and efficient fractionation of trace elements (TE) in environmental solids to be achieved but allows real-time studies on the leaching process be made. A novel five-step sequential extraction scheme was tested in on-line mode. The optimal conditions for the fractionation were chosen. Investigating elution curves provides important information on the efficiency of the reagents used, the leaching time needed for the separation of each fraction, and the potential mobility of HM forms. 

Figure 4.7 The selective or targeted mode of LMCS operation allows selected peaks to be collected sequentially in the cryoti ap, and then pulsed rapidly to the second column. The resulting peaks are naixow and tall provided that the second column phase selectivity and efficiency are adequate, they will also be resolved. The process is repeated as many times as required during the analysis. On this diagram, the lower ti ace response scale will be considerably less sensitive than on the upper ti ace.

At the end of the 2D experiment, we will have acquired a set of N FIDs composed of quadrature data points, with N /2 points from channel A and points from channel B, acquired with sequential (alternate) sampling. How the data are processed is critical for a successful outcome. The data processing involves (a) dc (direct current) correction (performed automatically by the instrument software), (b) apodization (window multiplication) of the <2 time-domain data, (c) Fourier transformation and phase correction, (d) window multiplication of the t domain data and phase correction (unless it is a magnitude or a power-mode spectrum, in which case phase correction is not required), (e) complex Fourier transformation in Fu (f) coaddition of real and imaginary data (if phase-sensitive representation is required) to give a magnitude (M) or a power-mode (P) spectrum. Additional steps may be tilting, symmetrization, and calculation of projections. A schematic representation of the steps involved is presented in Fig. 3.5. 

The issue of parallel versus sequential synthesis using multimode or monomode cavities, respectively, deserves special comment. While the parallel set-up allows for a considerably higher throughput achievable in the relatively short timeframe of a microwave-enhanced chemical reaction, the individual control over each reaction vessel in terms of reaction temperature/pressure is limited. In the parallel mode, all reaction vessels are exposed to the same irradiation conditions. In order to ensure similar temperatures in each vessel, the same volume of the identical solvent should be used in each reaction vessel because of the dielectric properties involved [86]. As an alternative to parallel processing, the automated sequential synthesis of libraries can be a viable strategy if small focused libraries (20-200 compounds) need to be prepared. Irradiating each individual reaction vessel separately gives better control over the reaction parameters and allows for the rapid optimization of reaction conditions. For the preparation of relatively small libraries, where delicate chemistries are to be performed, the sequential format may be preferable. This is discussed in more detail in Chapter 5. 

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