An application of the trost reaction to the stereoselective synthesis of trans-tetrasubstituted fluoroalkenes

The coupling of β-fluoroallylic acetates (1) with stabilised ester-enolates (3), in the presence of catalytic palladium(0), gave tetrasubstituted fluoroalkenes (2) in good yield and with generally satisfactory trans-stereoselectivity.     

Chromatographic screening for drugs of abuse using capillary columns II. Peak identification on support coated open tubular columns for a series of central nervous system stimulant drugs

Summary A system based on Kovats' Retention Indices is described for the identification of CNS stimulant drugs recovered from body fluids. Use is made of the difference in retention indices found on polar and non-polar GLC columns (l values) and the effect of operating temperature is discussed.     

Product set phenomena for countable groups

We develop in this paper novel techniques to analyze local combinatorial structures in product sets of two subsets of a countable group which are “large” with respect to certain classes of (not necessarily invariant) means on the group. Our methods heavily utilize the theory of C*-algebras and random walks on groups. As applications of our methods, we extend and quantify a series of recent results by Jin, Bergelson–Furstenberg–Weiss, Beiglböck–Bergelson–Fish, Griesmer and Di Nasso–Lupini to general countable groups.     

Superposition of non-ordinary state-based peridynamics and finite element method for material failure simulations

Superposition of non-ordinary state-based peridynamics and finite element method for material failure simulations, including crack propagation and strain localization is developed. By this approach, a peridynamic model capable of effectively treating strong and weak discontinuities is superimposed in the critical regions over an underlying finite element mesh placed over the entire problem domain. A rigorous variational framework of coupling local finite element and nonlocal peridynamics approximations that is free of blending parameters is developed. Several numerical examples involving mixed-model fracture, three-dimensional adaptive crack propagation and strain localization induced ductile failure demonstrate the rational and efficiency of the proposed superposition-based coupling approach.