Longevity evolution

From this beginning there has evolved a series of texts surpassing by far the scope and longevity envisioned by the founding Editorial Board. The McGraw-Hill Series in Chemical Engineering stands as a unique historical record of the development of chemical engineering education and practice. In the series one finds the milestones of the subject s evolution industrial chemistry, stoichiometry, unit operations and processes, thermodynamics, kinetics, and transfer operations. 

Adsorption of materials on to the surface of colloidal oxides or clays has been a popular means of introducing electrostatic effects into photoredox processes. Adsorption of and/or bipysRu on to colloidal oxides such as AI2O3 or Si02 can result in some increase in the yield of net photoredox products, but the real benefits are modest. Improvements can be obtained with clay mineral suspensions where it has been claimedthat cyclic water cleavage can be achieved. However, turnover numbers are low, the longevity is extremely poor, and gas evolution shows a puzzling oscillatory pattern. 

R.M. Nesse, G.C. Williams. Why We Get Sick The New Science of Darwinian Medicine. New York Times Books, 1994. (Note The quote on longevity is from pgs. 136-137. This book is an excellent overview of this field and gave this author some interesting insights on how chemicals interact with the body in the context of evolution.)... 

Similar mechanisms appear to have underpinned the evolution of longevity in species freed from predation and starvation. Lifespan reflects the rate of accumulation of damage, which varies with the metabolic rate, the production and elimination of free radicals, and the capacity for repair. Seen in this light, metabolic rate might even have been a factor in... 

A few fundamental principles that directly impact the level of efficiency associated with every specific metathesis reaction are worth stating at the outset of this discussion. As with any catalytic process, the rate of the primary reaction versus the hfetime of the working catalyst system - in effect, the turnover number (TON) - is a critical parameter. In the field of alkene/alkyne metathesis, there has been considerable evolution in the design and implementation of the catalysts (or precatalysts) that are used. Often, these advances have been driven by the desire to increase the TON by improving the longevity of the catalytic intermediates (catalyst robustness toward destmctive side reactions) or speeding up the rate of the slow step(s) in each metathesis cycle (or both). 

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