Narrow Results

The SEM observation on the cuticle of dorbeetle shows that the cuticle is composed of chitin fibers and protein matrix. The diameter of chitin fibers is from several to several-hundred nanometers. The observation also shows that there is a kind of dendritic fiber in the cuticle. The maximum pullout force of the dendritic fiber is analyzed based on its representative model. The analysis shows that the dendritic fibers can markedly increase the pullout force of the fibers and improve the fracture toughness of the cuticle.

A scanning electron microscope (SEM) observation on a Rufescens shell shows that the shell is a bio-ceramic composite consisting of aragonite sheets with nanometer scale and organic matrix. These nano-aragonite sheets are arranged in the shell in the form of helicoidal layup. The reason of the excellent fracture toughness of the shell is analyzed based on the maximal pullout force of the helicoidal layup of the aragonite sheets in the shell.

Application of double-barreled cannon stent grafts aortic repair (DoBAR) was reported in 2011 for extremely large aortic aneurysms of patients when there was no proper size of grafts for the emergent treatment. Fixation characteristics of the double stent grafts are obtained in a laboratory setting, and are incorporated with those of single Zenith TX2 grafts of sizes from 34 to 42mm. Radial stress and shear increase linearly with the oversizing parameter but decrease with increasing stent diameter. The slope of the linear relationship is practically the same for this group of grafts. When the original circular stent grafts of diameter 36 and 38mm are deformed to form DoBAR of diameter 44 or 46.4mm, the formation could provide higher radial stress and shear to secure fixation for endo-aortic repair. The experimental results of single and DoBAR grafts can be incorporated for clinical application of DoBAR for emergent treatment.