Nature of Structural Design and

Not everyone who attempts to explain structural failures claims to be able to make complete lists of causes. D. I. Blockley, whose otherwise ambitious book. The Nature of Structural Design and Safety, looks at the problem from several perspectives, including philosophical, historical, and analytical ones, makes no claims for completeness in his table of categories ... 

Blockley, D. I. The Nature of Structural Design and Safety. Chichester, West Sussex Ellis Horwood Limited, 1980. 

Cryptands of type 7-9 and derivatives thereof carry alkali cations [6.4], even under conditions where natural or synthetic macrocycles are inefficient. The selec-tivities observed depend on the structure of the ligand, the nature of the cation and the type of cotransported counteranion. Designed structural changes allow the transformation of a cation receptor into a cation carrier [6.1, 6.4]. The results obtained with cryptands indicated that there was an optimal complex stability and phase-transfer equilibrium for highest transport rates. Combined with data for various other carriers and cations, they give a bell-shaped dependence of transport rates on extraction equilibrium (Fig. 11), with low rates for too small or too large... 

Experiments in vitro with modular PKSs are considerably more straightforward than those with aromatic synthases. Whereas synthesis of aromatic polyketides requires the expression and purification of at minimum three activities, and as many as seven, a single multienzyme from a modular PKS can be competent for synthesis. Additionally, the design rules for the modular PKSs are considerably simpler, as there is a direct correlation between the number and nature of activities present and the resulting structure of the polyketide product. 

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