Stingrays can undulate their wide pectoral fins to thrust themselves and swim freely underwater.Many researchers have used bionics to directly imitate their undulating mechanism and manufacture undulatory underwater robots.Based on the limitations of the
For magmatic rocks,it is often found that zircon 206 Pb/238 U and 207 Pb/235 U ratios continuously plot on the concordia line with a relatively large age span for the same sample,which gives rise to large dating errors or even unrealistic dating results.A
Micro-textured surfaces have improved the tribological performance of contact surfaces under lubricated conditions;however,not practiced due to manufacturing challenges.In addition to simpler micro-pits or straight-trench type textures,sophisticated bioin