Abdominal aortic aneurysm (AAA) rupture is the clinical manifestation of an induced force exceeding the resistance provided by the strength of the arterial wall. This force is most frequently assumed to be the product of a uniform luminal pressure acting along the diseased wall. However fluid dynamics is a known contributor to the pathogenesis of AAAs, and the dynamic interaction of blood flow and the arterial wall represents the in vivo environment at the macro-scale. The primary objective of this investigation is to assess the significance of assuming an arbitrary estimated peak fluid pressure inside the aneurysm sac for the evaluation of AAA wall mechanics, as compared with the non-uniform pressure resulting from a coupled fluid-structure interaction (FSI) analysis. In addition, a finite element approach is utilised to estimate the effects of asymmetry and wall thickness on the wall stress and fluid dynamics of ten idealised AAA models and one non-aneurysmal control. Five degrees of asymmetry with uniform and variable wall thickness are used. Each was modelled under a static pressure-deformation analysis, as well as a transient FSI. The results show that the inclusion of fluid flow yields a maximum AAA wall stress up to 20% higher compared to that obtained with a static wall stress analysis with an assumed peak luminal pressure of 117 mmHg. The variable wall models have a maximum wall stress nearly four times that of a uniform wall thickness, and also increasing with asymmetry in both instances. The inclusion of an axial stretch and external pressure to the computational domain decreases the wall stress by 17%.

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A combination of MALDI−TOF MS and TOF/TOF collision-induced dissociation (CID) experiments was conducted on toluene diisocyanate (TDI) based carbodiimide and phenyl isocyanate (PI) carbodiimide mixtures to examine their degradation mechanisms and identify "fingerprint" side products associated with each of their synthesis. Findings include the first observance of the 3-methyl-1-phenyl-2phospholene-1-oxide (MPPO)/carbodiimide (CDI) catalyst-attached intermediate and the use of CID fragmentation to verify its chemical structure and degradation processes. This work is significant for two reasons: (1) it identifies extensive branching as the root-cause of viscosity build-up in carbodiimides and (2) it presents a BF 3initiated mechanism leading to polyguanidine formation.