| 2 | A tri-layer approach to controlling nanopore formation in oxide supports显示文摘A novel tri-layer approach for immobilizing metal nanoparticles in SiO2 supports is presented.In this work,we show that under rapid heating to temperatures of approximately 1,000 ℃,metal nanoparticles less than 15 nm in size will entrench in the SiO2 layer on a silicon wafer to create pores as deep as 250 nm.We studied and characterized this entrenching behavior and subsequent nanopore formation for a wide variety of metal nanoparticles,including Au,Ag,Pt,Pd,and Cu.We also demonstrate that an Al2O3 layer acts as a barrier to such pore formation.Thus,by creating a tri-layer architecture consisting of SiO2 on Al2O3 on silicon wafers,we can control the depth to which nanoparticles entrench between 3-5 nm.This small range allows one to entrench particles for the purpose of immobilization but still present them above the surface.The two advances of moving into the sub-15 nm size regime and of controlled particle immobilization through entrenchment have important implications in studying site-isolated and stabilized metal nanoparticles for applications in sensing,separations,and catalysis. | Abha A.Gosavi James L.Hedrick Peng-Cheng Chen Justin M.Notestein Chad A.Mirkin | 2019 | Nano Research2019，12，6： | 0 |
| 3 | Performance of a quasi-steady model for hovering hummingbirds显示文摘A quasi-steady model describing aerodynamics of hovering Ruby-throated hummingbirds is presented to study extent of the low-order model in representing the flow physics of the bird and also to separately quantify the forces from the translational,rotational,and acceleration effects.Realistic wing kinematics are adopted and the model is calibrated against computational fluid dynamics(CFD) simulations of a corresponding revolving-wing model.The results show that the quasi-steady model is able to predict overall lift production reasonably well but fails to capture detailed force oscillations.The downstroke-upstroke asymmetry is consistent with that in the previous CFD study.Further analysis shows that significant rotational force is produced during mid-stroke rather than wing reversal. | Jialei Song Haoxiang Luo Tyson L.Hedrick | 2015 | Theoretical & Applied Mechanics Letters2015，5，1： | 0 |
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