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A discharge channel with a chamfered wall not only has application in the design of modern Hall thrusters, but also exists where the channel wall is eroded, and so is a common status for these units. In this paper, the laws and mechanisms that govern the effect of the chamfered wall on the performance of a Hall thruster are investigated. By applying both experimental measurement and particle-in-cell simulation, it is determined that there is a moderate chamfer angle that can further improve the optimal performance obtained with a straight channel. This is because the chamfering of the wall near the channel exit can enhance ion acceleration and effectively reduce ion recombination on the wall, which is favorable to the promotion of the thrust and efficiency. However, the chamfer angle should not be too large; otherwise, both the density of the propellant gas and the distribution of the plasma potential in the channel are influenced, which is undesirable for efficient propellant utilization and beam concentration. Therefore, it is suggested that the chamfer shape of the channel wall is an important factor that must be carefully considered in the design of Hall thrusters. [ABSTRACT FROM AUTHOR]

This method provides access to Boc-protected β,γ-unsaturated α-amino acid esters with excellent yields and enantioselectivities. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed asymmetric OH insertion reaction was developed. Palladium complexes with chiral spiro bisoxazoline ligands promoted the insertion of α-aryl-α-diazoacetates into the OH bond of phenols with high yield and excellent enantioselectivity under mild reaction conditions. This palladium-catalyzed asymmetric OH insertion reaction provided an efficient and highly enantioselective method for the preparation of synthetically useful optically active α-aryl-α-aryloxyacetates. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed asymmetric OH insertion reaction was developed. Palladium complexes with chiral spiro bisoxazoline ligands promoted the insertion of α-aryl-α-diazoacetates into the OH bond of phenols with high yield and excellent enantioselectivity under mild reaction conditions. This palladium-catalyzed asymmetric OH insertion reaction provided an efficient and highly enantioselective method for the preparation of synthetically useful optically active α-aryl-α-aryloxyacetates. [ABSTRACT FROM AUTHOR]

The article highlights the chemical equations involved in the enantioselective palladium-catalyzed insertion of aryl-diazoacetates into the O-H bonds of phenols.

Tumor metastasis is the major cause of cancer-related death especially in human hepatocellular carcinoma (HCC). Although microRNAs have been implicated in tumor development, the roles of miR-124 in HCC metastasis are still not well understood. We conducted functional analysis in this study to investigate miR-124. We observed that miR-124 significantly retarded the wound healing and migration of HCC SMMC-7721 and BEL-7404 cells. Further analysis indicated miR-124 directly targeting the transcriptional factor Sp1 which is an important transcription factor for the integrin αV subunit gene transcription. Co-transfection of miR-124 with the luciferase reporter containing Sp1 3′ untranslated region (UTR) significantly suppressed the luciferase activities. While mutation of the binding site of miR-124 in Sp1 mRNA 3′UTR completely abrogated the suppression of miR-124. Overexpression of miR-124 resulted in robust downregulation of Sp1 and integrin αV expression at either mRNA or protein level. Ectopic expression of miR-124 in HCC dramatically repressed the wound healing and migration in vitro and tumor metastasis in mouse experiments. Our findings demonstrated that miR-124 played as an important role in regulation of integrin αV expression in HCC, and reintroduction of miR-124 might be an alternative therapeutic strategy for controlling integrin αV expression in HCC. [ABSTRACT FROM AUTHOR]