The reaction of active methylene moieties, pyrazolones, thiazolylacetonitriles, phenols and alkyl pyridazinones with benzylidene-malononitrile in ethanol in presence of chitosan afforded aminopyrancarbonitriles, pyranopyrazole, thiazolopyridines, chromenes, and pthalazines in yields comparable to those obtained in ethanolic piperidine. Much lower yields were obtained in aqueous solutions.

SumilznryThe reaction of cyclo-octanone seinicarbazone(2) with SeO, leads to cyclo-octeno-1,2,3-selenadiazole (3) from which, on heating to 170-220°, cyclo-octyne (5), the lowest stable cycloalkyne, can be prepared in good yields.

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The energy-sensitive detection of heavy ions with calorimetric low temperature detectors was investigated in the energy range of E=0.1-1 MeV/amu, commonly used for accelerator mass spectrometry (AMS). The detectors used consist of sapphire absorbers and superconducting aluminum transition edge thermometers operated at T approximately 1.5 K. They were irradiated with various ion beams (13C, 197Au, 238U) provided by the VERA tandem accelerator in Vienna, Austria. The relative energy resolution obtained was DeltaE/E=(5-9) x 10(-3), even for the heaviest ions such as 238U. In addition, no evidence for a pulse height defect was observed. This performance allowed for the first time to apply a calorimetric low temperature detector in an AMS experiment. The aim was to precisely determine the isotope ratio of 236U/238U for several samples of natural uranium, 236U being known as a sensitive monitor for neutron fluxes. Replacing a conventionally used detection system at VERA by the calorimetric detector enabled to substantially reduce background from neighboring isotopes and to increase the detection efficiency. Due to the high sensitivity achieved, a value of 236U/238U=6.1 x 10(-12) could be obtained, representing the smallest 236U/238U ratio measured at the time. In addition, we contributed to establishing an improved material standard of 236U/238U, which can be used as a reference for future AMS measurements.