New Accelerating Tube for 4 MV Van de Graaff Accelerator

The accelerating tube with diametrically magnetized ring magnets for the bending of backstreaming electrons was constructed for the 4 MV Van de Graaff accelerator of Kyoto University. The X-ray yield due to the electron loading was reduced to a factor of about 100 ; and the ion beam current was increased by a factor of about five compared with that of the old tube which had plane electrodes with small accelerating apertures. Characteristics of evacuation, beam convergence and accelerator operation are described ; and typical results of ion analysis are given for hydrogen, helium, nitrogen, neon and argon

Asymmetric desymmetrization of meso-diols by C(2)-symmetric chiral 4-pyrrolidinopyridines.

In this work we developed C(2)-symmetric chiral nucleophilic catalysts which possess a pyrrolidinopyridine framework as a catalytic site. Some of these organocatalysts effectively promoted asymmetric desymmetrization of meso-diols via enantioselective acylation