Abdominal aortic aneurysm (AAA) is an irreversible bulge in the artery with higher prevalence among the elderlies. increase of the aneurysm diameter by time is a fatal phenomenon which will lead to its sidewall rupture. invasive surgical treatments are vital in preventing from AAA development. these approaches however have considerable side effects. Targeted drug delivery using microbubbles (MBs) has been recently employed to suppress the AAA growth. the present study is aimed to investigate the surface adhesion of different types of drug-containing MBs to the inner wall of AAA through ligandreceptor binding, using fluid-structure interaction (FSI) simulation by using a patient CT-scan images of the vascular system. The effect of blood flow through AAA on MBs delivery to the intended surface was also addressed. For this purpose, the adherence of four types of MBs with three different diameters to the inner surface wall of AAA was studied in a patient with 40-mm diameter aneurysm. The effects of the blood mechanical properties on the hematocrit (Hct) percentage of patients suffering from anemia and diabetes were studied. Moreover, the impact of variations in the artery inlet velocity on blood flow was addressed. Simulation results demonstrated the dependency of the surface density of MBs (SDM) adhered on the AAA lumen to the size and the type of MBs. It was observed that the amount of SDM due to adhesion on the AAA lumen for one of the commercially-approved MBs (Optison) with a diameter of 4.5 μm was higher than the other MBs. Furthermore, we have shown that the targeted drug delivery to the AAA lumen is more favorable in healthy individuals (45% Hct) compared to the patients with diabetes and anemia. Also, it was found that the targeted drug delivery method using MBs on the patients having AAA with complicated aneurysm shape and negative inlet blood flow velocity can be severely affected. Abdominal aortic aneurysm (AAA) is one of the most common types of cardiovascular diseases (CVDs) occurring in the middle part of the aorta. AAA is originated from the changes in the mechanical properties of the vessel wall leading to permanent focal dilation of 50% 1. At present, small AAAs, with a diameter of less than 55 mm in men and less than 50 mm in women, are examined with regular monitoring in terms of size. At this point, the growth rate is approximately 3-10 mm/year. The patient needs surgery in case of AAA excessive enlargement beyond these values 2-4. However, the minimally invasive or so-called endovascular method also has some complications, including difficulty and complexity of the operation when AAA is closed to one of the visceral veins. Also, about 20 percent of grafts cannot completely remove the damaged vessel from the circulatory system 5,6. Another problem with the endovascular method is the durability of this method due to endoleak (continuous blood leakage around stents), which results in shorter durability of this type of treatment 5. Despite these drawbacks and challenges, effective treatment is still...
Based on the first-order non-linear von Karman theory, cylindrical bending of functionally graded (FG) plates subjected to mechanical, thermal, and combined thermo-mechanical loadings are investigated. Analytical solutions are obtained for an FG plate with various clamped and simply-supported boundary conditions. The closed form solutions obtained are very simple to be used in design purposes. The material properties are assumed to vary continuously through the thickness of the plate according to a power-law distribution of the volume fraction of the constituents. The effects of non-linearity, material property, and boundary conditions on various response quantities are studied and discussed. It is found that linear analysis is inadequate for analysis of simply-supported FG plates even in the small deflection range especially when thermal load is present. Also it is shown that bending—extension coupling can not be seen in response quantities of clamped FG plates. Also an exact solution is developed for the one-dimensional heat conduction equation with variable heat conductivity coefficient.
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