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The phase transition in layered MoS2 has attracted wide attention but the detailed phase transition process is still unclear. Here, the H → T′ phase transition mechanism of single- and bilayer MoS2 induced by lithium intercalation has been systematically studied using first principles. The results indicated that the lithium intercalation can effectively reduce the sliding barrier of the S atom layer. Moreover, we demonstrated that the phase transition process in bilayer MoS2 is induced by S atom transition one by one instead of the collective behavior of the S atoms. Importantly, we found that the phase transition process in bilayer MoS2 consists of the formation, diffusion and recombination of S vacancies, and the phase transition originates from interlayer lithium defects. In addition, the lithium defects cannot induce phase transition in monolayer MoS2 due to the larger sliding barrier of the S atom. [ABSTRACT FROM AUTHOR]

Evodia rutaecarpa ( E. rutaecarpa) has been used to treat aches, vomiting and dysentery in traditional Chinese medicine. However, as a mildly toxic herb its toxic components have not been elucidated. An attempt was made to illuminate the hepatotoxic constituents of E. rutaecarpa. The 50% ethanol extracts of E. rutaecarpa from 19 different sources were used to establish UPLC fingerprints and administered to mice at a dose of 35 g/kg (crude medicine weight/mouse weight) once daily for 14 days. Serum levels of alanine transaminase, aspartate aminotransferase and liver coefficient were used as indices of liver injury. Additionally, the characteristic peaks of 19 fingerprints were identified. Spectrum-effect relationships between fingerprints and hepatotoxic indicators were analyzed using bivariate correlation analysis (BCA). The UPLC fingerprints were established and a total of 28 main compounds were identified. Because of the inherent variations in chemical compositions, the liver injury levels were different among the E. rutaecarpa samples from 19 sites of production. BCA results indicated that compounds dihydrorutaecarpine, 6-acetoxy-5-epilimonin, goshuyuamide I, 1-methyl-2-[( Z)-5-undecenyl]-4(1H)-quinolone, 1-methyl-2-[(4 Z,7Z)-4,7-tridecadienyl]-4(1H)-quinolone, evocarpine and 1-methyl-2-[(6 Z,9 Z)-6,9-pentadecadienyl]-4(1H)-quinolone were tentatively determined as the primary hepatotoxic components. The present study provides a valuable method for the discovery of hepatotoxic constituents by combination of fingerprints and hepatotoxicity index. [ABSTRACT FROM AUTHOR]