Abstract: A process for the preparation of acylamido derivatives by reaction of a compound of the formula Z - N = C = O, wherein Z is an optionally substituted alkyl-, aryl- (preferably phenyl or naphthyl) or cycloalkyl or optionally substituted heterocyclic, preferably a penicillanic acid or a cephalosporanic acid nucleus, having carboxyl groups and an optionally present hydroxy group protected, with a carboxylic acid of the formula ##STR1## wherein Z.sup.1 is an optionally substituted hydrocarbon group, in the presence of a catalyst selected from the group consisting of substituted pyridines and their N-oxides, optionally substituted imidazoles or their N-oxides, optionally substituted benzimidazoles or their N-oxides, and optionally substituted imidazo [1,2-.alpha.] pyridines or their N-oxides.

Abstract: Novel heterocyclic amides of the formula ##STR1## wherein R is selected from the group consisting of lower alkyl and aryl optionally substituted with at least one member of the group consisting of chlorine, fluorine, nitro, amino and lower alkyl and a tertiary alkyl group, R.sub.1 is selected from the group consisting of hydrogen, lower alkyl, carboxyl, lower alkoxycarbonyl, an alkali metal, alkaline earth metal or amine salt of carboxyl, a carbamyl, cyano, an amino and chlorine, R.sub.

Abstract: An improved filtering arrangement for a converter circuit in which a highpass filter, tuned to have a cutoff frequency which is less than the lowest harmonic to be filtered is provided instead of the customary plurality of filters tuned to individual harmonic currents. In a 12 pulse converter circuit, at least one highpass filter which is tuned to filter out harmonics starting with the fifth harmonic and which has a resonant frequency above the 11th harmonic is used.