How to include the surface effect aournd a nano-sized crack

Dear Mechanicians,

I am reading some papers on the surface effects of nano-sized elements(bars,beams, plates, films) or defects(inhomogeneities, inclusions, cavities) these days. Some researchers have studied the surface effects on the stress state around a circular hole or an elliptic hole. I wonder if there is any research work on the surface effect around a nano-sized crack. Thank you!

Best Regards,

Jun