Process design, rational

Industrial scale polymer forming operations are usually based on the combination of various types of individual processes. Therefore in the computer-aided design of these operations a section-by-section approach can be adopted, in which each section of a larger process is modelled separately. An important requirement in this approach is the imposition of realistic boundary conditions at the limits of the sub-sections of a complicated process. The division of a complex operation into simpler sections should therefore be based on a systematic procedure that can provide the necessary boundary conditions at the limits of its sub-processes. A rational method for the identification of the subprocesses of common types of polymer forming operations is described by Tadmor and Gogos (1979). 

Using computers and a process of rational chemical design, chemists arrived at a basic structure that they used as a starting point (lead compound). 

Perfect the tools to study reaction mechanisms of chemical and biochemical reactions, so the processes can be observed directly and more efficient syntheses can be designed rationally. 

Process design involves making decisions about a series of matters, on as rational and quantitative a basis as possible, given the information available. The following is an illustrative list of such matters but not an exhaustive one the items are not all mutually exclusive. 

Three approaches may be taken to discover new herbicides. They are (a) the random screening of chemicals, (b) the use of known herbicides as lead compounds for a synthesis program, and (c) the design of compounds interfering with known metabolic processes - the "rational" approach. There are no publications in the field of herbicide discovery that would suggest that the latter approach has advanced very much beyond the theoretical stage. The second approach, sometimes referred to as the "me-too" approach, has both positive and negative features. The... 

In most adsorption processes the adsorbent is contacted with fluid in a packed bed. An understanding of the dynamic behavior of such systems is therefore needed for rational process design and optimization. What is required is a mathematical model which allows the effluent concentration to be predicted for any defined change in the feed concentration or flow rate to the bed. The flow pattern can generally be represented adequately by the axial dispersed plug-flow model, according to which a mass balance for an element of the column yields, for the basic differential equation governing llie dynamic behavior,... 

In the process of rational drug design, there are a couple of choices. First, we can try variations on compounds that have worked well in the past. This approach is reasonable, respectable, and often successful. When a particular type of bacterium evolves a strain that is immune to our medicines, we can take a medicine that worked previously and tack on a new group of atoms or change a bond to see if we can make it effective again. This approach, called the combinatorial approach, has yielded many useful compounds. But the approach has also been likened to a tree with many roots it can sample a lot of soil, but only soil in the vicinity of the tree. If there is a new drug with a completely new structure, then the combinatorial approach may not find it. 

Novel aspects of protein extraction with reversed-micelles include both fundamental studies and process design studies/approaches. Fundamental studies are essential in order to design a reversed-micelles based extraction process in a rational manner. Such theoretical programs have been initiated and are providing a better understanding of the partitioning and transport phenomena in such systems (31). In this book, Jolivalt tal. (32) review the modeling aspects and the applications of reversed micelles for protein separations. 

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