Emphysema and influenza directly affect alveolar sacs and cause problems in lung performance during the breathing cycle. In this study, the effects of Emphysema and Influenza on alveolar sac’s air flow characteristic...Emphysema and influenza directly affect alveolar sacs and cause problems in lung performance during the breathing cycle. In this study, the effects of Emphysema and Influenza on alveolar sac’s air flow characteristics are investigated through Computational Fluid Dynamics (CFD) simulation. Both normal and Emphysemic alveolar sac models with varying collapsed volumes resulting from influenza virus replication were developed. Maximum, area average pressure, and wall shear stress (WSS) in collapsed and open alveolar sacs models were compared. It was found that a collapse at half of the volume at the bottom of the alveolar sacs’ models would cause a decrease in average and maximum pressure values and yield higher WSS values for fluid flow during the breathing cycle. On the other hand, a quarter volume collapse at the bottom and side of the model resulted in higher values for average and maximum pressure and WSS. Additionally, results also showed that a combination of alveolar sacs closure and Emphysema would generally lead to an increase in fluid pressure and average WSS during breathing. Maximum WSS was observed during exhalation and maximum WSS decrease occurred during inhalation. Findings are in good agreement with previous studies and suggest that emphysema and influenza virus affect fluid flow and may contribute to alveolar sac closure. However, more realistic simulations should include the fluid-solid interaction studies.展开更多
Microtubules (MT) are of great engineering importance due to their potential applications as sensors, actuators, drug delivery, and others. The MT properties/mechanics are greatly affected by their biomechanical envir...Microtubules (MT) are of great engineering importance due to their potential applications as sensors, actuators, drug delivery, and others. The MT properties/mechanics are greatly affected by their biomechanical environment and it is important to understand their biological function. Although microtubule mechanics has been extensively studied statically, very limited studies are devoted to the biomechanical properties of microtubule undergoing deformation and vibration. In this study, we investigate the biomechanical properties of the microtubule under bending deformation and free vibration using 3D finite element analysis. Results of force-deformation and vibration frequencies and mode shapes obtained from the finite element analysis are presented. The results indicate that the force-deformation characteristics vary with time/phases and become non-linear at higher time intervals. The modes of MT vibration and frequencies are in the GHz range and higher modes will involve combined bending, torsion and axial deformations. These higher modes and shapes change their deformation which might have implications for physiological and biological behavior, especially for sensing and actuation and communication to cells. The bending force-deformation characteristics and vibration modes and frequencies should help further understand the biomechanical properties of self-assembled microtubules.展开更多
文摘Emphysema and influenza directly affect alveolar sacs and cause problems in lung performance during the breathing cycle. In this study, the effects of Emphysema and Influenza on alveolar sac’s air flow characteristics are investigated through Computational Fluid Dynamics (CFD) simulation. Both normal and Emphysemic alveolar sac models with varying collapsed volumes resulting from influenza virus replication were developed. Maximum, area average pressure, and wall shear stress (WSS) in collapsed and open alveolar sacs models were compared. It was found that a collapse at half of the volume at the bottom of the alveolar sacs’ models would cause a decrease in average and maximum pressure values and yield higher WSS values for fluid flow during the breathing cycle. On the other hand, a quarter volume collapse at the bottom and side of the model resulted in higher values for average and maximum pressure and WSS. Additionally, results also showed that a combination of alveolar sacs closure and Emphysema would generally lead to an increase in fluid pressure and average WSS during breathing. Maximum WSS was observed during exhalation and maximum WSS decrease occurred during inhalation. Findings are in good agreement with previous studies and suggest that emphysema and influenza virus affect fluid flow and may contribute to alveolar sac closure. However, more realistic simulations should include the fluid-solid interaction studies.
文摘Microtubules (MT) are of great engineering importance due to their potential applications as sensors, actuators, drug delivery, and others. The MT properties/mechanics are greatly affected by their biomechanical environment and it is important to understand their biological function. Although microtubule mechanics has been extensively studied statically, very limited studies are devoted to the biomechanical properties of microtubule undergoing deformation and vibration. In this study, we investigate the biomechanical properties of the microtubule under bending deformation and free vibration using 3D finite element analysis. Results of force-deformation and vibration frequencies and mode shapes obtained from the finite element analysis are presented. The results indicate that the force-deformation characteristics vary with time/phases and become non-linear at higher time intervals. The modes of MT vibration and frequencies are in the GHz range and higher modes will involve combined bending, torsion and axial deformations. These higher modes and shapes change their deformation which might have implications for physiological and biological behavior, especially for sensing and actuation and communication to cells. The bending force-deformation characteristics and vibration modes and frequencies should help further understand the biomechanical properties of self-assembled microtubules.
