Lipids with longer chain lengths showed greater viscosities and greater storage and loss moduli. The results also showed that the viscosity decreased with a decreasing volume fraction and increasing temperature. The oxygen microbubbles showed a shear-thinning behavior. The rheological behavior was characterized using a rotating rheometer. Additionally, the mean edema score, wet/dry ratio, and inflammation scores were lower in the DSPC group. Beyond 12 hours, the mean %SpO2 and PaO2 of rats was greater in the DSPC group. Rats in the first group had significantly greater survival than others. Results showed 77.8%, 20%, and 10% survival in the DSPC, DBPC, and DPPC groups. Arterial blood gas analysis and pulse oximetry were then performed. After inducing the disease in rats, the distearoylphosphatidylcholine (DSPC), dibehenoylphosphatidylcholine (DBPC), or dipalmitoylphosphatidylcholine (DPPC) OMBs were administered intraperitoneally at a 100 mL/kg dose every 12 h, up to 36 h. We replicated an ARDS rat model by intratracheal administration of lipopolysaccharide at a 24 mg/kg dose. Previous studies demonstrated significant improvements in systemic oxygenation and mortality upon administering OMBs. Oxygen microbubbles (OMBs) consist of a lipid shell with an oxygen core and have potential to augment oxygenation to manage ARDS. ARDS Management strategies involve extracorporeal membrane oxygenation (ECMO) and mechanical ventilation, but none of these methods improve the mortality rates. It is characterized by hypoxemia and damage to the lung alveoli. Our outcomes suggest it is possible to determine a new spatial scale to describe the collisional process, depending on the specific confining conditions.Īcute respiratory distress syndrome (ARDS) causes 75,000 deaths in the U.S., annually. Alternatively, we rationalize our findings using a kinematic approximation to highlight the relevant scale of the problem. Indeed, the confinement strongly affects the spatial scale where the particle is affected by the bottom wall and, accordingly, the dimensionless results can not be collapsed in a single master curve, using the particle size as a characteristic length. Consequently, their motion cannot be described by the analytical framework introduced for the infinite system.
However, the results indicate that confined particles have a distinct dynamics response when approaching the wall. We analyze several systems varying the radius of the bead and show the excellent agreement of our results with previous analytical approaches. The simulations results are contrasted with the experimental findings, obtaining a good agreement. After adjusting the parameters of the numerical model, we analyze the particle dynamic under several confinement conditions. Similar conditions are simulated using a resolved CFD-DEM approach.
Besides, the experimental values of the terminal velocity obtained for different confinements are also in very good agreement with previous theoretical formulations. For unconfined configurations, our experimental findings are in excellent agreement with well-established analytical frameworks, used to describe the forces acting on the sphere. Particle trajectories for spheres of two types of materials are measured using a high-speed digital camera. In the present work, we investigate experimentally and numerically the motion of solid macroscopic spheres (Brownian and colloidal effects are negligible) when settling from rest in a quiescent fluid toward a solid wall under confined and unconfined configurations.