Fall, classification and cosmogenic records of the Sabrum (LL6) chondrite
摘要:
Abstract— The petrographic and chemical characteristics of a fresh Indian meteorite fall at Sabrum are described. Its mean mineral composition is defined by olivine (Fa31.4), orthopyroxene (Fs25.1,Wo2.0), clinopyroxene (Wo45En45.6Fs9.4) and plagioclase (An10.6Ab83.6Or5.8). The meteorite shows moderate shock features, which indicate that it belongs to the S4 category. Based on mineralogical and chemical criteria the meteorite is classified as an LL6 brecciated veined chondrite. Several cosmogenic radioisotopes (46Sc, 7Be, 54Mn, 22Na and 26Al), noble gas (He, Ne, Ar, Kr and Xe), nitrogen isotopes, and particle tracks density have been measured. Concentrations of cosmogenic 21Ne and 38Ar indicate that its cosmic‐ray exposure age is 24.8 Ma. Small amounts of trapped Kr and Xe, consistent with petrologic class 5/6, are present. The track density in olivines is found to be (1.3 ± 0.3) × 106/cm2. Activities of most of the short‐lived isotopes are lower than those expected from solar cycle variation. 22Na/26Al (1.12 ± 0.02) is found to be significantly anomalous, being ˜25% lower than expected from the Climax neutron monitor data. These results indicate that the cosmic‐ray flux during the terminal segment of the meteoroid orbit was low. The activities of 26Al and 60Co and the track density indicate small meteoroid size with a radius ˜15 cm.
Zur Kenntnis der Triterpene. 139. Mitteilung. �ber die Konstitution des ?-Amyrins und seine Beziehungen zu ?-Amyrin
作者:A. Meisels、O. Jeger、L. Ruzicka
DOI:10.1002/hlca.19490320363
日期:——
Es wurde die Übereinstimmung der Anordnung von 29 Kohlenstoffatomen, sowie der Konfiguration derRinge A undB bei α- und β-Amyrin bewiesen. Die beiden Verbindungen unterscheiden sich in der Anordnung einer Methylgruppe im Ringe E, welcher im α-Amyrin an den Kohlenstoffatomen 19 und 20 je eine Methylgruppe trägt, während sich im β-Amyrin am Kohlenstoffatom 20 bekanntlich zwei Methylgruppen befinden