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Abstract Long‐standing federal drug‐control policy aims to reduce the flow of narcotics into the USA, in part by intercepting cocaine shipments en route from South American production regions to North American consumer markets. Drug interdiction efforts operate over a large geographic area, containing complex drug trafficking networks in a dynamic environment. The extant interdiction models in the operations research and location science literature do not realistically model the objectives of and constraints on the interdiction forces, and therefore counterdrug organizations do not employ those models in their decision‐making processes. This article presents three new models built on the maximal covering location problem (MCLP): the maximal covering location problem for interdiction (MCLP‐I), multiple‐demand maximal covering location problem (MD‐MCLP), and multiple‐type maximal covering location problem (MT‐MCLP). These are novel formulations that permit multiple types of demands and facilities to be covered, and the utility of these formulations is demonstrated in the context of counterdrug operations. Optimal interdiction locations are determined within the geography of the Central American transit zone, using a coupled GIS and optimization framework. The results identify the optimal interdiction locations for known or estimated drug shipments and can constrain those optimal locations by differentiating among drug traffickers, the types of interdiction resources, and agency jurisdictions. This research both demonstrates the flexibility in designing alternative interdiction scenarios and presents novel covering models that may be extended to other application areas and operational contexts. 

Abstract Inverse electron demand Diels–Alder reactions betweens‐tetrazines and strained dienophiles have numerous applications in fluorescent labeling of biomolecules. Herein, we investigate the effect of the dienophile on the fluorescence enhancement obtained upon reaction with a tetrazine‐quenched fluorophore and study the possible mechanisms of fluorescence quenching by both the tetrazine and its reaction products. The dihydropyridazine obtained from reaction with a strained cyclooctene shows a residual fluorescence quenching effect, greater than that exerted by the pyridazine arising from reaction with the analogous alkyne. Linear and ultrabroadband two‐dimensional electronic spectroscopy experiments reveal that resonance energy transfer is the mechanism responsible for the fluorescence quenching effect of tetrazines, whereas a mechanism involving more intimate electronic coupling, likely photoinduced electron transfer, is responsible for the quenching effect of the dihydropyridazine. These studies uncover parameters that can be tuned to maximize fluorogenic efficiency in bioconjugation reactions and reveal that strained alkynes are better reaction partners for achieving maximum contrast ratio.