Yujie Wei

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In conventional metals, there is plenty of space for dislocations-line defects whose motion results in permanent material deformation-to multiply, so that the metal strengths are controlled by dislocation interactions with grain boundaries and other obstacles. For nanostructured materials, in contrast, dislocation multiplication is severely confined by the(More)
Mechanical property of dumbbell-like Au-Fe(3)O(4) nanoparticles (NPs) is investigated from a synthetic point of view by overgrowing Au(2) on the Au(1)-Fe(3)O(4) NPs. The competitive growth of Au(2) on the preformed Au(1)-Fe(3)O(4) NPs induced an interesting "tug-of-war" between Au(2) and Fe(3)O(4) in the formed Au(2)-Au(1)-Fe(3)O(4) ternary nanostructure.(More)
The strength-ductility trade-off has been a long-standing dilemma in materials science. This has limited the potential of many structural materials, steels in particular. Here we report a way of enhancing the strength of twinning-induced plasticity steel at no ductility trade-off. After applying torsion to cylindrical twinning-induced plasticity steel(More)
  • YuJie Wei
  • 2008
We develop a physical model to describe the kinetic behavior in cell-adhesion molecules. Unbinding of noncovalent biological bonds is assumed to occur by both bond dissociation and bond rupture. Such a decomposition of debonding processes is a space decomposition of the debonding events. Dissociation under thermal fluctuation is nondirectional in a(More)
Core-shell nanoparticles (NPs) with lipid shells and varying water content and rigidity but with the same chemical composition, size, and surface properties are assembled using a microfluidic platform. Rigidity can dramatically alter the cellular uptake efficiency, with more-rigid NPs able to pass more easily through cell membranes. The mechanism accounting(More)
Bending rigidity and Gaussian bending stiffness are the two key parameters that govern the rippling of suspended graphene-an unavoidable phenomenon of two-dimensional materials when subject to a thermal or mechanical field. A reliable determination about these two parameters is of significance for both the design and the manipulation of graphene morphology(More)
The functionalized lipid shell of hybrid nanoparticles plays an important role for improving their biocompatibility and in vivo stability. Yet few efforts have been made to critically examine the shell structure of nanoparticles and its effect on cell-particle interaction. Here we develop a microfluidic chip allowing for the synthesis of structurally(More)
The two-dimensional crystalline structures in graphene challenge the applicability of existing theories that have been used for characterizing its three-dimensional counterparts. It is crucial to establish reliable structure-property relationships in the important two-dimensional crystals to fully use their remarkable properties. With the success in(More)
Grain refinement can make conventional metals several times stronger, but this comes at dramatic loss of ductility. Here we report a heterogeneous lamella structure in Ti produced by asymmetric rolling and partial recrystallization that can produce an unprecedented property combination: as strong as ultrafine-grained metal and at the same time as ductile as(More)
There are prevailing concerns with the critical dimensions when conventional theories break down. Here we find that the Griffith criterion remains valid for cracks down to 10 nm but overestimates the strength of shorter cracks. We observe the preferred crack extension along the zigzag edge in graphene, and explain this phenomenon by local strength-based(More)