Magnetic Switching Dynamics and Tunnel Magnetoresistance Effect Based on Spin-Splitting Noncollinear Antiferromagnet Mn_(3)Pt

In comparison to ferromagnets,antiferromagnets are believed to have superior advantages for applications in next-generation magnetic storage devices,including fast spin dynamics,vanishing stray fields and robust against external magnetic field,etc.However,unlike ferromagnetic orders,which could be detected through tunneling magnetoresistance effect in magnetic tunnel junctions,the antiferromagnetic order(i.e.,Néel vector)cannot be effectively detected by the similar mechanism due to the spin degeneracy of conventional antiferromagnets.Recently discovered spin-splitting noncollinear antiferromagnets,such as Mn_(3)Pt with momentum-dependent spin polarization due to their special magnetic space group,make it possible to achieve remarkable tunneling magnetoresistance effects in noncollinear antiferromagnetic tunnel junctions.Through first-principles calculations,we demonstrate that the tunneling magnetoresistance ratio can reach more than 800% in Mn_(3)Pt/perovskite oxides/Mn_(3)Pt antiferromagnetic tunnel junctions.We also reveal the switching dynamics of Mn_(3)Pt thin film under magnetic fields using atomistic spin dynamic simulation.Our study provides a reliable method for detecting Néel vector of noncollinear antiferromagnets through the tunnel magnetoresistance effect and may pave its way for potential applications in antiferromagnetic memory devices.

The effects of Age of Acquisition on an L2 learner’s Ultimate Attainment

This paper focuses on generalizing different theories towards the age effect on the ultimate attainment of second language learners since it has long been a controversial topic in researchers’mind.In this paper,it gives evidences on cases in favor of the Critical Period Hypothesis,which claimed the loss of language learning ability after puberty and presents counter-evidences on the successful acquisition of second language in adult learners.It has reached into a conclusion that consists the viewpoint drawn on previous analysis and confirmed the possibility in ultimate second language attainment for late learners.

Exploring the N-terminus region： Synthesis, bioactivity and 3D-QSAR of allatostatin analogs as novel insect growth regulators

Allatostatins （ASTs）, a family of insect neuropeptide, can inhibit juvenile hormone （JH） biosynthesis by the corpora allata （CA） in Diploptera punctata, and therefore be regarded as potential leads for the discovery of new insect growth regulators （1GRs）. But several shortcomings, such as their sensitivity to peptidases and high cost, impeded their practical application in pest management. In order to discover new IGRs, one AST analog B1 possessing non-peptide group was discovered with high ability to inhibit JH biosynthesis in vitro （IC50： 0.09 μmol/L） in our previous studies. In the present work, two series of B1 analogs with different substituents on the N-terminus region were designed and synthesized. The result suggested that benzene showed better activity than other heterocycles, and the para-substitution on the benzene was beneficial for activity. Moreover, analogs with logP value over 2.0 exhibited good activity, which indicated the hydrophobicity is important to the bioactivity. Three dimension quantitative structure-activity relationship （3D-QSAR） studies were performed to highlight the structural require- ments of ASTanalogs, which demonstrated introduction of bulkier substituents on the N-terminus would increase the activity. Analog Ⅱ12 （IC50： 0.08 μmol/L） exhibited similar inhibitory activity to the lead B1, but its synthetic route was simpler than B1. Therefore, Ⅱ12 could be used as a new lead compound for the discovery eco-friendly IGRs.