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The finite-amplitude evolution of neutral perturbations to the Cushman-Roisin frontal geostrophic model for a simple upwelling front with spatially varying potential vorticity is determined. It is shown that the sinuous and varicose modes are governed by the “bright” and “dark” NLS equations, respectively. This implies that the sinuous modes can exhibit Benjamin-Feir instability (while the varicose modes do not), suggesting the possibility that envelope solitons can form on a frontal outcropping. Exploiting the underlying Hamiltonian structure, it is nevertheless shown that all monotomc parallel front solutions of the Cushman-Roisin model are nonlinearly stable in the sense of Liapunov.

The stereochemistry of the major isomer of 14,15-dihydroxy-5,8,10,12-eicosatetraenoic acid formed from 15-hydroperoxyeicosatetraenoic acid in human leukocytes was determined. The structure (erythro-14(R),15(S]-14,15-dihydroxy-5,8-cis-10,12-trans-eicosatetraenoi c acid) was assigned based on sodium arsenite thin-layer chromatography, NMR spectroscopy, and comparison with material prepared by total synthesis. This compound was found to inhibit leukotriene B4-induced superoxide anion generation in human neutrophils (IC50 = 10(-8)-10(-7) M). Superoxide anion generation induced by either formylmethionyl-leucyl-phenylalanine or arachidonic acid was not affected.

A detailed NMR analysis of epimeric pairs of 1-methylated steroids in the A/B cis and Δ4-series has confirmed earlier configurational assignments. One-methyl steroids in the A/B trans series and the 1-methyl hydrocortisone synthesized therefrom are revised from the α to β-configuration. One-β-methyl-5α and 1β-methyl-Δ4 steroids were judged to be distorted from the normal chair-formed A-ring conformation, the former into the twist and the latter into the alternative half-chair form.

The reaction of dichloroketen with 6,6-diphenylfulvene afforded a crystalline cycloadduct identified as cis-7,7-dichloro-4-diphenylmethylenebicyclo[3,2,0]hept-2-en-6-one by n.m.r. and chemical degradation studies. Similarly, the adduct obtained from dichloroketen and 8,8-diphenylbenzofulvene was shown to be cis-2,2-dichloro-2,2a,7,7a-tetrahydro-7-diphenylmethylene-1H-cyclobut[a]inden-1-one by n.m.r. analysis.

The reactions of dichloroketen with diphenylfulvene and diphenylbenzofulvene afforded 1,2-mono-adducts whose structure and stereochemistry were proved by detailed n.m.r. analysis.