Time, discovery

GEN.65. I. Prigogine, Probing into time. Discovery, Sept. 1980, University of Texas, Austin,... 

The first, made by Ichikawa et al. [29], was the evidence that rhodium or iridium cluster carbonyls, when adsorbed on zinc oxide, titania, lanthanum oxides, zirconia or magnesia, could produce quite selectively ethanol by the Fischer-Tropsch synthesis. This was a timely discovery (metallic catalytic particles produced by traditional methods could not reproduce such selectivity) since it came at a period of geopolitical tension after the Kippur war in 1973, which caused the price of crude oil to increase enormously. Therefore, that period was characterized by intense research into selective Fischer-Tropsch catalysis. 

The race to find the next blockbuster has never been more important in the pharmaceutical industry. The very existence of many companies may depend on the timely discovery of new chemical entities that can be developed into the next Celebrex or Lipitor . Adding to this is the need to reduce cost and increase shareholder value. Consequently, the productivity of the pharmaceutical industry has dramatically fallen short of its own expectations (1). 

Time DISCOVERY 2-3 years 1 year 30 year 1/2-1 year 1-2 years 1-2 years... 

Although a considerable number of 1-azirines have been prepared in a very short time, discovery of new and refinement of old synthetic techniques are clearly needed. Finally, the 1-azirine ring system is potentially a very valuable starting point for the preparation of new and unusual heterocyclic compounds. Already a number of very interesting aziridines have been prepared and 1-azirines were key intermediates for the preparation of the l-azabicyclo[2.1.0]pentane and l-azabicyclo[1.1.0]butane ring systems. 

Robey, J. (2003). Bioterror through time. Discovery Channel Series, February 21, 2003. Available at http //dsc. discovery.com/anthology/spotlight/bioterror/history/history.html, p. 3 (accessed January 2007). 

Heiner, I., Boesgaard, T.M., Kristensen, R.M. (2009). First time discovery of Loricifera from Australian waters and marine caves. Marine Biology Research 5, 529-546. 

Characterisation of binuclear 65 (Scheme 11) as an intermediate in oxidation of Pt to Pt has been a timely discovery [24, 25], concurrent in 2009 with detection of symmetric binuclear Pd -Pd complexes that decompose by C-X bond... 

J. S. Edkins (1863-1940) is best known for his controversial (at the time) discovery of gastrin in 1905. What is less appreciated is his work on a spiral organism, most probably H. felis, in the stomach of cats. Apart from his critical contributions to the field of croquet, Edkins deserves credit for these two seminal observations in the field of gastroenterology. 

Figure 9. Illustration of search-time discovery of reaction sequences. A breadth-first search is used to find a pathway of molecules linking the reactant hit list to the product hit list...

This method of search-time discovery can be used as well for the searching of explicit schemes. In that case one could consider the molecule network as containing coloured edges, with each colour representing a single literature document. A successful pathway must consist entirely of edges of the same colour. One should expect far fewer hits from a search restricted in this manner, and a shorter search time as well. 

Determine the most practical method of searching explicit schemes, either prior registration or search-time discovery ... 

Figure 10. Comparison of search times and number of hits between standard REACCS RSS (equivalent to automatic prior registration), search-time discovery of explicit schemes, and first-order implicit schemes...

A Scheme-RSS search over both explicit and first-order implicit schemes, using the method of search-time discovery. The search was carried out for one-, two-, and three-step schemes. 

Unfortunately, further study did not in general duplicate these results. The second example, a six-to-five ring contraction, returned two one-step hits and two summary reactions using non-scheme REACCS. Search-time discovery of explicit schemes returned the same results, but performance suffered by a factor of 12. Searching of implicit schemes returned a few more answers, but the cost in search time was a factor of over 53. 

Another example, synthesis of indoles from anilines, fell somewhat in the middle. Search-time discovery of explicit schemes took 3.6 times longer than standard REACCS or prior registration. Searching for implicit schemes took over 11 times as long to complete, and returned only a few extra answers. The low number of additional implicit schemes could be explained by the high degree of historical interest in this reaction, and therefore the relatively large number of explicit schemes in the literature. 

Overall, it can be seen that searches of explicit schemes by search-time discovery requires about three to 10 times as much computer resource as a comparable search using the method of prior-registration. Although a modest decrease in performance is acceptable in order to accommodate a single methodology for all types of scheme searches, we are not convinced that chemists using the system would accept the performance penalty. 

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