Chemical control, automation nature

Earlier in this chapter we considered the nature of chemical control (Section 5.1), the character and degree of automation (Section 5.2) with the choice between discontinuous and continuous analysis, the role of electroanalysis in automated chemical control (Section 5.3) and automated electroanalysis in laboratory control (Section 5.4). 

Of the three above-mentioned major classes of natural biopolymers, chemical synthesis of nucleic adds (in particular DNA) and proteins had already been achieved by the Merrifield solid-phase synthesis method a computer-controlled automated synthesizer became commerdally available more than 20 years ago. However, the chemical synthesis of polysaccharides like cellulose was far more difficult than that of the former two classes. Polysaccharide synthesis is the repetition of glycosylation, the most fimdamental reaction in carbohydrate chemistry (Scheme 2). 

In looking back over 26 years of commercial experience It Is appropriate to comment on product quality. Significant improvements have been made compared with the commercial Delrin of 1960 in terms of melt stability, molecular weight distribution and control, the level and uniformity of physical properties and the color and colorability of natural color product. These product improvements were achieved by persistent chemical and engineering effort on the chemistry of the process, modernization of equipment, compounding technology and automated measurement and control systems. 

The human body is a remarkably complex biochemical process, and it shares many attributes with more traditional process control problems that have been discussed in earlier chapters. In the event that a body fails to achieve the robust level of self-regulation that occurs naturally (cf. Chapter 24), there are opportunities for medical intervention, often involving the administration of a therapeutic agent (or drug) in a prescribed manner. The therapy can be optimized using open-loop methods, but it is often advantageous to automate the process, thus removing the human from the feedback loop (much as a chemical plant removes the operator from the loop in the transition from manual control to... 

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