The favorable selective toxicity of neonicotinoid insecticides (represented here by imidacloprid, thiacloprid, and a nitromethylene analogue) for insects versus mammals is not shared by three of their N-unsubstituted imine derivatives or by nicotine or epibatidine. The same selectivity pattern is evident at the receptor level, i.e., the insect nicotinic acetylcholine receptor (nAChR) versus mammalian nAChR subtypes (alpha1, alpha3, alpha4, and alpha7) assayed independently. The insect-selective compounds are not protonated with a nitroimine, cyanoimine, or nitromethylene group and the mammalian-selective compounds are ionized at physiological pH. We propose that the negatively charged tip of the nitro or cyano group (not a partial positive charge at imidazolidine N-1 as suggested earlier) interacts with a putative cationic subsite of the insect nAChR. This contrasts with the mammalian nAChRs where the iminium cation (+C-NH2 <--> C =+NH2) of the neonicotinoid imine derivatives or ammonium nitrogen of nicotine or epibatidine interacts with the anionic subsite.

In teacher preparation most supervisory feedback is deferred, allowing learners to perform skills incorrectly and delivery of on-site immediate feedback may interrupt instructional flow. This study used a multiple baseline design to examine effects of immediate, corrective feedback delivered via wireless technology on completion of three-term contingency trials. Participants were five preservice special education teachers working on academic skills with students with special needs in elementary and middle school classrooms. Corrective, immediate feedback was shown to be an effective way to increase completion of three-term contingency trials by teachers. During baseline, percentage of completion ranged from 30-92. With corrective, immediate feedback, all five teachers reached criterion level of 90% completion. Overall, mean percentage of correct student responses increased 3 to 17 percentage points over baseline results for four of the five teachers. All teachers rated the method as beneficial. Implications for practice are discussed.

:The 2-benzoylcyclohexane-1,3-diones, the triketones, are a novel class of bleaching herbicides whose mode of action is the inhibition of the enzyme p-hydroxyphenylpyruvate dioxygenase. The structureÈactivity relationships of this chemical class are elucidated. An ortho-substituent on the aryl ring is an absolute requirement for herbicidal activity. Beyond that, the herbicidal activity of these compounds is best correlated with the overall electron deÐciency of the benzoyl group induced by 2,4-disubstitution of the aryl ring, with the most electron-deÐcient analogs being the most active. Moreover, the degree of electron deÐciency of the benzoyl group is outwardly manifested in the acidity of the molecule. The activity of these compounds is further enhanced through additional aromatic substitution in the 3-position of the aryl ring. The greater activity of these 2,3,4-trisubstituted aryl analogs over the 2,4-disubstituted aryl analogs is due to increased intrinsic activity.1998 Society of Chemical Industry ( Pestic. Sci., 54, 377È384 (1998)

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