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Since the effect of magnetic fields on blood flow is not fully understood or studied comprehensively, this paper, for the first time, addresses the effect of uniform magnetic fields with different intensities on the pulsatile non-Newtonian blood flow in an elastic artery with axially symmetrical single and double stenoses using the commercial software COMSOL Multiphysics 5.1. The results are suggestive that an increase in the percent stenosis increases the pressure drop, which is more dramatic in double stenosis. Moreover, for a given percent stenosis, increasing the Hartmann (Ha) number, in addition to increasing the pressure drop, increases the amount by which the pressure drop is raised. The shear stress results revealed that increasing the magnetic field intensity results in the reduction of the vortex region formed in the back of the stenosis, reducing the area prone to disease, which can resolve pathological issues. The impact of the magnetic field was found to be decreased by increasing the percent stenosis. It was also observed that the percentage difference between the maximum wall shear stresses for various percent stenoses is reduced by increasing the Ha number for both single and double stenoses.

Intraperitoneal (IP) chemotherapy has revived hopes during the past few years for the management of peritoneal disseminations of digestive and gynecological cancers. Nevertheless, a poor drug penetration is one key drawback of IP chemotherapy since peritoneal neoplasms are notoriously resistant to drug penetration. Recent preclinical studies have focused on targeting the aberrant tumor microenvironment to improve intratumoral drug transport. However, tumor stroma targeting therapies have limited therapeutic windows and show variable outcomes across different cohort of patients. Therefore, the development of new strategies for improving the efficacy of IP chemotherapy is a certain need. In this work, we propose a new magnetically assisted strategy to elevate drug penetration into peritoneal tumor nodules and improve IP chemotherapy. A computational model was developed to assess the feasibility and predictability of the proposed active drug delivery method. The key tumor pathophysiology, including a spatially heterogeneous construct of leaky vasculature, nonfunctional lymphatics, and dense extracellular matrix (ECM), was reconstructed in silico. The transport of intraperitoneally injected magnetic nanoparticles (MNPs) inside tumors was simulated and compared with the transport of free cytotoxic agents. Our results on magnetically assisted delivery showed an order of magnitude increase in the final intratumoral concentration of drug-coated MNPs with respect to free cytotoxic agents. The intermediate MNPs with the radius range of 200–300 nm yield optimal magnetic drug targeting (MDT) performance in 5–10 mm tumors while the MDT performance remains essentially the same over a large particle radius range of 100–500 nm for a 1 mm radius small tumor. The success of MDT in larger tumors (5–10 mm in radius) was found to be markedly dependent on the choice of magnet strength and tumor-magnet distance while these two parameters were less of a concern in small tumors. We also validated in silico results against experimental results related to tumor interstitial hypertension, conventional IP chemoperfusion, and magnetically actuated movement of MNPs in excised tissue.

Atherosclerosis develops due to different hemodynamic factors, among which time-averaged Wall shear stress (mean WSS) and Oscillatory shear index (OSI) are two of the most important. These two factors not only depend on flow geometry, but are also influenced by rheological characteristics of blood. Since analytical solutions are limited to simple problems and since experimental tests are costly and time consuming, CFD solutions been prominently and effectively used to solve such problems. We conducted a numerical study via ADINA 8.8 software on the non-Newtonian pulsatile flow of blood through an elastic blood artery with single and consecutive stenosis. The studied stenosis cross sectional area was 70 % that of the unstenosed artery. The single stenosis results were compared with the consecutive stenosis results. The five non-Newtonian flow models, the Carreau model, the Carreau-Yasuda model, the modified Casson model, the power-law model, and the generalized power-law model, were used to model the non-Newtonian blood flow. The obtained results showed that increasing the number of stenoses would lead to reduced length of the oscillatory area after the first stenosis, thus forming another oscillatory area with a larger length after the second stenosis. Thus, a consecutive stenosis would develop a larger disease prone area. Upon examining the mean WSS and OSI, we found that, as compared with the other models, the modified Casson model and the power-law model produced predictions for the most extent of damage to endothelial cells and the most disease prone areas, respectively.

Tumor cells are known for their increased glucose uptake rates even in the presence of abundant oxygen. This altered metabolic shift towards aerobic glycolysis is known as the Warburg effect. Despite an enormous number of studies conducted on the causes and consequences of this phenomenon, little is known about how the Warburg effect affects tumor growth and progression. We developed a multi-scale computational model to explore the detailed effects of glucose metabolism of cancer cells on tumorigenesis behavior in a tumor microenvironment. Despite glycolytic tumors, the growth of non-glycolytic tumor is dependent on a congruous morphology without markedly interfering with glucose and acid concentrations of the tumor microenvironment. Upregulated glucose metabolism helped to retain oxygen levels above the hypoxic limit during early tumor growth, and thus obviated the need for neo-vasculature recruitment. Importantly, simulating growth of tumors within a range of glucose uptake rates showed that there exists a spectrum of glucose uptake rates within which the tumor is most aggressive, i.e. it can exert maximal acidic stress on its microenvironment and most efficiently compete for glucose supplies. Moreover, within the same spectrum, the tumor could grow to invasive morphologies while its size did not markedly shrink.

This article investigates the pulsatile and turbulent blood flows in flexible artery with single and double stenoses. The changes in pressure drop, mean wall shear stress (WSS), radial displacement of the artery, and oscillating shear index are investigated. Similar to experimental data, the results of the present study show that a laminar flow occurs for stenosis of up to 70%, and for 80% stenosis the flow is turbulent. The mean WSS analysis shows that assuming the flow is laminar causes more errors than assuming the walls are solid. The comparison of the results for single stenosis with those for double stenosis reveals that the dilation in the arterial walls in double stenoses is much more common than in single stenosis. Therefore, the maximum mean WSS in double stenoses is less than that in single stenosis. The results also indicate that the axial pressure drop in double stenoses is higher than that in single stenosis.

Research on the development and incidence of cardiovascular diseases has revealed the importance of vascular wall shear stress. In this paper, the vascular wall shear stress was numerically simulated in an elastic vessel with simple and consecutive Stenosis during a pulsatile laminar non-Newtonian blood flow using ADINA 8.8. The cross-sectional area of the studied stenosis was 70% of the unstenosed vascular cross-sectional area. The results of the simple stenosis were compared with those of the double stenosis. Five non-Newtonian models of Carreau, Carreau-Yasuda, Casson, Power Law, and Generalized Power Law were employed to simulate the non-Newtonian properties of blood. The axial velocity values at the maximum flow rate showed that in both simple and consecutive Stenosis, the highest and lowest axial velocities occur in the Generalized Power Law and Power Law models, respectively. Wall shear stress profiles at the maximum flow rate showed that the Power Law model underestimates the stress values compared to other non-Newtonian models and the Newtonian model. In general, results showed that the Power Law model is not suitable for simulating the non-Newtonian behavior of blood.

The turbulent pulsatile blood flow through stenosed arteries considering the elastic property of the wall is investigated numerically. During the numerical model validation both standardk-εmodel and RNGK-εmodel are used. Compared with the RNGK-εmodel, the standardK-εmodel shows better agreement with previous experimental results and is better able to show the reverse flow region. Also, compared with experimental data, the results show that, up to 70% stenosis, the flow is laminar and for 80% stenosis the flow becomes turbulent. Assuming laminar or turbulent flow and also rigid or elastic walls, the results are compared with each other. The investigation of time-averaged shear stress and the oscillatory shear index for 80% stenosis show that assuming laminar flow will cause more error than assuming a rigid wall. The results also show that, in turbulent flow compared with laminar flow, the importance of assuming a flexible artery wall is more than assuming a rigid artery wall.