Land submerged to carbonate platform by conodonts: paleoenvironment reconstruction of the western Gangdese in Tibet during Triassic

The western Gangdese in Tibet during Triassic was previously considered to be a part of the Gangdese Oldland (Zhao ZZ et al.,2001;Fig.1).If the Gangdese Oldland did exist,it means no prospect of petroleum exploration of the Triassic strata in western Gangdese area.Fortunately,the recent biostratigraphic progresses don’t support the existence of the Gangdese Oldland.This paper aims to briefly introduce the new paleogeographic interpretation and the reason that the western Gangdese in the Triassic was marine instead of terrigenous on the basis of the recent conodont data.

Syndiotactic Polymerization of Styrene and Copolymerization with Ethylene Catalyzed by Chiral Half-sandwich Rare-earth Metal Dialkyl Complexes

The syndiotactic polymerization of styrene（St） and the copolymerization of St with ethylene（E） were carried out by using a series of chiral half-sandwich rare-earth metal dialkyl complexes（Cp^x＊） as the catalysts. The complexes are Ln（CH2SiMe3）2（THF）（1-4： Ln = Sc（1）, Ln = Lu（2）, Ln = Y（3）, Ln = Dy（4）） bearing chiral cyclopentadienyl ligand containing bulky cylcohexane derivatives in the presence of activator and AliBu3. For the St polymerization, a high activity up to 3.1 × 10^6 g of polymer mol Ln^-1·h^-1 and a high syndiotactic selectivity more than 99% were achieved. The resulting syndiotactic polystyrenes（sPSs） have the molecular weights（Mn） ranging from 3700 g·mol^-1 to 6400 g·mol^-1 and the molecular weight distributions（Mw/Mn） from 1.40 to 5.03. As for the copolymerization of St and E, the activity was up to 2.4 × 10^6 g of copolymer mol Sc^-1·h^-1·MPa^-1, giving random St-E copolymers containing syndiotactic polystyrene sequences with different St content in the range of 15 mol%-58 mol%. These results demonstrate that the bulky cyclopentadienyl ligands of the chiral half-sandwich rare-earth metal complexes effectively inhibit the continued insertion of St monomers into the（co）polymer chain to some extent in comparison with the known half-sandwich rare-earth metal complexes.

Improvements on the particle identification with dead cell and side leakage corrections for the electromagnetic calorimeter of the Alpha Magnetic Spectrometer

Background The electromagnetic calorimeter(ECAL)of the Alpha Magnetic Spectrometer(AMS-02)measures the energy of electrons/positrons and separates them from protons.Currently,there are five dead cells in the ECAL which affect the reconstructed energy of particles.The particle identification power of the ECAL decreases when particles pass through these dead cells or close to the ECAL border.Purpose To improve the ECAL particle identification for particles pass through these dead cells or close to the ECAL border.Methods An improved ECAL particle identification estimator using the electromagnetic shower shape is developed with dead cell and side leakage corrections.Results For events passing through dead cells,with this new estimator,the proton rejection power is improved by a factor of 2.2 and positron purity is improved from 31 to 50%in the energy range of 500–800 GeV.Conclusion The new estimator works well for event passing through dead cells or close to the ECAL border.