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Abstract:The acetone extract of the aerial parts of Sideritis caesarea Duman, Aytaç & Başer (Lamiaceae) afforded the flavonoids penduletin (1) and apigenin (2) and 6 glycosylated flavonoids, (7), andThe compounds were identified by the use of 1D-and 2D-NMR and UV spectroscopic techniques and by comparisons with the reported data. The acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitory activities of the acetone, methanol, and water extracts of the plant and of the flavones penduletin and apigenin were evaluated at 200 µ g/mL. The water extract exhibited better activity against the enzyme AChE as compared to both the acetone and the methanol extracts. Penduletin (1) showed significant activity against BChE (66.58%) while apigenin (2) showed weak activity against both enzymes.

Heat capacity measurements in zero and applied magnetic fields have been performed on a series of Er 1−x Tb x Al 2 pseudobinary Laves-phase alloys. Different anomalies that change with Tb concentrations have been observed. These anomalies represent multiple magnetic ordering phenomena, similar to those reported in Er 1−x Pr x and Er 1−x Dy x Al 2 alloys. In common, all alloys contain mixtures of lanthanide metals with opposite signs of the second-order Steven's operators, which were believed to cause competition between the magnetoelastic, crystalline electric field, and quadrupolar effects. This competition gives rise to the observed multiple magnetic ordering transitions in Er 1−x Pr x and Er 1−x Dy x Al 2 alloys. Tb and Er also have opposite signs of second-order Steven's factors, and therefore the observed anomalies in the Er 1−x Tb x Al 2 alloys may also be interpreted in terms of competing quadrupolar, magnetoelastic, and crystalline electric field effects. The magnetocaloric properties of the Er 1−x Tb x Al 2 alloy system have also been evaluated.

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