Microstructure and mechanical performance of AZ31/6061 lap joints welded by laser-TIG hybrid welding with Zn-Al alloy filler metal

A series of Zn-xAl(x=0-35 wt.%)alloy filler metals were designed to join AZ31 Mg alloy to 6061 Al alloy by laser-TIG hybrid welding.The effect of Al content on the wettability of filler metals,microstructure evolution and strength of joint was investigated.The results indicated that the strength of joints was improved with the increase of Al content in filler metals.When Zn-15Al filler was used,the ultimate fracture load reached the maximum of 1475.3 N/cm,which was increased by 28%than that with pure Zn filler.The reason is that the Al element acts as a"reaction depressant"in filler metal,which contributes to inhibiting the dissolution of Mg base metal and the Mg-Zn reaction.The addition of appropriate quantity of Al element promoted the precipitation of Al-rich solid solution instead of Zn solid solution.The MgZn_(2) IMCs have lower lattice mismatch with Al solid solution than Zn solid solution,thus the strength of joints is improved.However,the excessive addition of Al caused the formation of brittle Mg32(Al,Zn)49 ternary compounds,leading to the deterioration of joint performance.

LDL receptor-related protein 1 (LRP1),a novel target for opening the blood-labyrinth barrier(BLB)

Inner ear disorders are a cluster of diseases that cause hearing loss in more than 1.5 billion people worldwide.However,the presence of the blood-labyrinth barrier(BLB)on the surface of the inner ear capillaries greatly hinders the effectiveness of systemic drugs for prevention and intervention due to the low permeability,which restricts the entry of most drug compounds from the bloodstream into the inner ear tissue.Here,we report the finding of a novel receptor,low-density lipoprotein receptor-related protein 1(LRP1),that is expressed on the BLB,as a potential target for shuttling therapeutics across this barrier.As a proof-ofconcept,we developed an LRP1-binding peptide,IETP2,and covalently conjugated a series of model small-molecule compounds to it,including potential drugs and imaging agents.All compounds were successfully delivered into the inner ear and inner ear lymph,indicating that targeting the receptor LRP1 is a promising strategy to enhance the permeability of the BLB.The discovery of the receptor LRP1 will illuminate developing strategies for crossing the BLB and for improving systemic drug delivery for inner ear disorders.