New pre-scission neutron multiplicity (v~") data for Li-, ' 0-, and Ne-induced fission are presented, spanning a fissility range from 0.60 to 0.85. Fission time scales have been deduced for two extreme assumptions regarding the mean excitation energy during fission. It is found for fusion-fission reactions that the fission time scale is independent of fissility, within a factor 1.5. A comparison of time scales deduced from v~"measurements for fast-fission with quasifission timescales deduced from the rotation angle of the composite system allows a minimum fusion-fission time scale of 30X10 ' s to be determined. For the most fissile system, fast-fission (fission without barrier) is shown to be up to three times faster than fusion-fission. Using a model to interpret the fusion-fission time scales, it is concluded that motion in the fission direction is strongly overdamped. This means that the dynamics of fission are dominated by a slow di6'usion towards scission, and not by the potential energy surface. It is shown that such a picture can explain the observed lack of dependence of the fission time scale on fissility.

To elucidate the active conformation of indometacin that differentiates between cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2), the stereochemistry around the N-benzoylated indole moiety of indometacin was studied. Resolution of stable atropisomers as representative conformations was found to be possible by restricting rotation about the N-C7' and/or C7'-C1' bond. Only the aR-isomer showed specific inhibition of COX-1, and COX-2 was not inhibited by either atropisomer.

Radially polarized intense terahertz (THz) radiation behind a thin foil irradiated by ultrahigh-contrast ultrashort relativistic laser pulse is recorded by a single-shot THz time-domain spectroscopy system. As the thickness of the target is reduced from 30 to 2 µm, the duration of the THz emission increases from 5 to over 20 ps and the radiation energy increases dramatically, reaching ∼10.5mJ per pulse, corresponding to a laser-to-THz radiation energy conversion efficiency of 1.7%. The efficient THz emission can be attributed to reflection (deceleration and acceleration) of the laser-driven hot electrons by the target-rear sheath electric field. The experimental results are consistent with that of a simple model as well as particle-in-cell simulation.

2',6'-Disubstituted N-benzoylated carbazole derivatives were found to exhibit atropisomerism. The bulky substituents restricted rotation about the N-C7' and C7'-C1' bonds to separate four atropisomers, in which rotation about the C7'-C1' bond was in perfect concert with rotation about the N-C7' bond. Complete geared rotation without slippage at 37 °C for 7 days was observed for the first time. Conformational analysis clarified the preference for the gear system over other internal conversion pathways.

The iodocyclization of γ,δ-unsaturated alcohols in the presence of a silyl enol ether produced cis-2,5-disubstituted tetrahydrofurans in one pot via siloxy intermediates. N-Iodosuccinimide (NIS) effectively worked as an activator of the double bonds in the substrates and the silyl enol ether. Application to an expedient synthesis of the adjacent bis-tetrahydrofuran core of Annonaceous acetogenins with a cis/threo/cis relative stereochemistry is also described.