Fluid-Structure Interaction in Biological Media / FSI
Ali Vazifedoost Saleh; Nasser Fatouraee; Mahdi Navidbakhsh; Farzad Izadi
Volume 11, Issue 2 , June 2017, , Pages 153-165
Abstract
In terms of mechanical behavior, human’s speaking and generating voice is a sophisticated process which is resulted in interaction between flowing air through the larynx and oscillating functionality of vocal folds. The sulcus vocalis is one of the individual cases of scarring in which the superficial ...
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In terms of mechanical behavior, human’s speaking and generating voice is a sophisticated process which is resulted in interaction between flowing air through the larynx and oscillating functionality of vocal folds. The sulcus vocalis is one of the individual cases of scarring in which the superficial lamina propria is absent over the length of the vocal fold and can procreate several disorders in voice generation. In this study, for the first time, the effects of sulcus vocalis on vibrating functionality of vocal folds have been assessed by employing finite element numerical modeling. Two-dimensional models of either healthy or sulcus vocal folds were implemented which each one is coupled and solved via LS-dyne software. Also, the three e-layer linear elastic model was utilized for the structure phase and the arbitrary Lagrangian-Eulerian (ALE), incompressible continuity, and Navier- Stokes relations were used for the fluid domain. Type II patients’ self-excited oscillations have been exhibited and compared with the healthy model. The results of the healthy model were assessed and compared with numerical and experimental results of previous studies. Moreover, the influences of the sulcus not only on the flow components but also on the oscillating functionality of the vocal folds have been evaluated. The results indicated that the frequency of vocal folds’ vibrations and the value of volume flux tends to be remarkably declined and boosted up respectively.
Tissue Engineering
Mehdi Navidbakhsh; Mehdi Sajjadi; Simzar Hosseinzade
Volume 11, Issue 1 , May 2017, , Pages 51-61
Abstract
Tissue engineering is a promising approach for developing viable alternative for current treatments of cardiovascular diseases such as autologous vessel and synthetic bypass graft transplantation. One of the major challenges in development of an applicable tissue engineered vessel is proper design of ...
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Tissue engineering is a promising approach for developing viable alternative for current treatments of cardiovascular diseases such as autologous vessel and synthetic bypass graft transplantation. One of the major challenges in development of an applicable tissue engineered vessel is proper design of scaffold. Scaffolds are served to mimic the natural in vivo environment of cells where they interact and behave according to the mechanical cues obtained from the surrounding extracellular matrix. In recent studies alginate hydrogels containing silk fibroin protein have shown sufficient biological capability for vascular cells attachment, spreading, growth and metabolic activity. The purpose of this study was to evaluate the mechanical properties of mentioned hydrogels as scaffolds for vascular tissue engineering. Elastic modulus of linear region, yield strain and stress and compliance of three types of Alginate based hydrogel with different synthesis procedures were obtained via uniaxial tensile test of dogbone shaped specimens and thick-wall cylinders stress-strain equations. Results were compared to find the optimal formulation and synthesis process for mimicing mechanical properties of native tissue. Results of this study shows that while the proposed formulation of alginate/fibroin hydrogel lacks required mechanical stiffness, flexibility and strength; hybrid dual-network hydrogels of alginate/fibroin/polyacrylamide with a two-steps synthesis process and cross-linked by Fe3+ and Ca2+ cations promote suitable mechanical properties to be used as vascular tissue engineering scaffolds. Adding polyacrylamide to alginate-firoin hydrogels increased its elastisity modulus from 46 kPa to 480 kPa with a two step gelation process which makes it more similar to arteries wall tissue mechanically.
Fluid-Structure Interaction in Biological Media / FSI
Borhan Alhoseini Hamedani; Mehdi Navidbakhsh; Hosein Ahmaditafti
Volume 5, Issue 1 , June 2011, , Pages 45-56
Abstract
In this paper, study of mechanical properties of human blood vessels is considered, especially those of related to the Coronary Artery Bypass Graft (CABG). Unfortunately more than 30% of saphenous grafts are re-occluded within 10 years while mammary artery shows better results. In this study elastomechanical ...
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In this paper, study of mechanical properties of human blood vessels is considered, especially those of related to the Coronary Artery Bypass Graft (CABG). Unfortunately more than 30% of saphenous grafts are re-occluded within 10 years while mammary artery shows better results. In this study elastomechanical properties of human saphenous vein, which is common in CABG, is studied. Stress-stretch behavior of these samples after a cyclic loading was obtained and large deformation formulation was used to obtain real stress and stretch ratio of these vessels. Then a fourth order polynomial was used to show nonlinear behavior of these results. Results show that blood vessel stiffness in longitudinal direction is two times greater than circumferential direction, while it is more than 74% stretchable in the circumferential direction. So modulus of elasticity in longitudinal direction is greater than circumferential direction. If we continue stretching until final rupture after maximum strength, longitudinal samples will be broken down faster than circumferential samples because of collagen fibers orientation.
Tissue Engineering
Mehdi Navidbakhsh; Milade Jafarnejad
Volume 3, Issue 4 , June 2009, , Pages 299-306
Abstract
The cancer changes the cytoskeleton of the cells .This change has some effects on the cell mechanobiology and will lead to some changes in the deformability of the cells. The moving ability of the cancer cells would be more than healthy cells. Thus, they can migrate through the tissue in human body. ...
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The cancer changes the cytoskeleton of the cells .This change has some effects on the cell mechanobiology and will lead to some changes in the deformability of the cells. The moving ability of the cancer cells would be more than healthy cells. Thus, they can migrate through the tissue in human body. In this survey, a valid FEM of a cancer cell is presented. Then the effects of various factors such as membrane thickness, elasticity, strain, and frequency response are studied during a process of being converted from normal cells into cancerous malignant cells. Besides, the initial mathematical models are provided. The results clarify that an increase in membrane elasticity, strain, and frequency would lead to increase in the reaction force. However, an increase in the membrane thickness decreases the reaction force.
Cell Biomechanics / Cell Mechanics / Mechanobiology
Morteza Khalilian; Mehdi Navidbakhsh; Mojtaba Rezazade; Mahmoud Chizari; Poupak Eftekhari Yazdi
Volume 2, Issue 1 , June 2008, , Pages 21-28
Abstract
Recently, considerable biomedical attention has centered on the mechanical properties of living tissues at the single cell level. Stiffness is an important parameter in determining the physical properties of living tissues. Indeed, stiffness changes of the ovum as a single cell pose a unique challenge ...
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Recently, considerable biomedical attention has centered on the mechanical properties of living tissues at the single cell level. Stiffness is an important parameter in determining the physical properties of living tissues. Indeed, stiffness changes of the ovum as a single cell pose a unique challenge in determining the sequence of fertilization. The ovum's extracellular layer has been reported to be altered following fertilization in a process described as Zona reaction. In the present study, the Young's modulus of Zona Pellucida of the mouse ovum was evaluated using micropipette aspiration technique. By incorporating exact engineering principles into the cell mechanics and extract appropriate formula, the Young's modulus of metaphase II (MII) and pronuclear (PN) was measured. The experimental results clearly demonstrated that the mouse Zona Pellucida hardened following fertilization. This study involves the contents of Reproductive Biology and Mechanics, and opens up a new trail of thought for evaluating the quality of mammalian oocytes and embryos.
