Field and pressure response of Yb compounds close to a quantum critical point

YbCu_5−x Al _x provides the possibility to tune ground state properties by a change of the valence due to the Cu/Al substitution, by pressure as well as by the application of a magnetic field. Near to the critical concentration x _cr≈1.5 non-Fermi-liquid properties (NFL) are obvious, obeying hyperscaling. If magnetic order sets in for x>1.5, the application of moderate magnetic fields quenches order and again NFL features become evident. Hyperscaling in this case indicates strongly interacting spin fluctuations.     

Constituents of Kenyan Gardenia volkensii

A new triterpenoid, 3-oxo-22alpha-hydroxy-olean-12-en-28-oic acid (1), oleanolic acid (2) and a known iridoid, 10-hydroxy-1-oxo-7-iriden-11-oic acid methyl ester (3) have been isolated from the dichloromethane extract of the dried seeds of Gardenia volkensii. Their structures were established by 1D and 2D NMR spectroscopic and MS methods.