Artifacts edge effect

All of these effects, fluorescence artifacts, edge effects, insolubility, etc., have been understood for some time. But even taking them all into account still wasn t enough to explain a mysterious problem that had probably been observed in many labs. Dr Brian Shoichet of UCSF elaborates We were looking for inhibitors of 3-lactamase. We found all these hits and they were all noncompetitive, which was weird, and they were all time-dependent, which was weird. None of those things were impossible, but to have them all We had twenty of these molecules and so we said, Well, let s just make sure they re not inhibiting chymotrypsin. And they did. Then we said, Let s make sure they don t inhibit dihydrofolate reductase. And they did. We said, Let s make sure they don t inhibit P-galactosidase. And they did. We knew we were in trouble. Usually, when that happens in pharma, people drop the project. ... 

Typical examples of mononucleation are the deposition of silver on electrolyticaUy grown Ag(lOO) crystals (Fig. 3) [156-159], and the formation of 2D condensed organic films, such as isoquinoline [160], thymine [163], or coumarin [162-164] on mercury electrodes. These experiments demonstrate that the rate of nucleation is more strongly dependent on the applied supersaturation than the growth rate. Extreme care has to be taken in mononucleation experiments to avoid artifacts from edges or defect contributions of the substrate or catalytic effects of impurities [161,162]. 

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