Design and 3D-model of a dynamic bubble trap for cardiopulmonary bypass

The use of extracorporeal circulation systems (cardiopulmonary bypass pumps, ECMO) can lead to brain and coronary artery microembolism, which significantly reduces postoperative rehabilitation and often leads to severe complications. Microembolism occurs when oxygen or air microbubbles (MBs) enter the arterial system of patients. Existing CPB pumps come with built-in bubble trap systems but cannot remove bubbles in the circuit. ECMO devices have arterial filters but cannot reliably filter out <40 μm bubbles in a wide flow range. We have proposed an alternative method that involves the use of an efficient dynamic bubble trap (DBT) for both large and small bubbles. The design includes development of two DBT variants for hemodynamic conditions of adult and pediatric patients. The device is installed in the CPB pump and ECMO outlet lines. It provides sufficient bubble separation from the lines in a blood flow of 3.0–5.0 L/min for adults and 0.5–2.0 L/min for children. The developed computer models have shown that MBs smaller than 10 μm can be filtered. The use of this device will greatly reduce the likelihood of air embolism and provide the opportunity to reconsider the concept of expensive arterial filters.

The benefits of diligence: how precise are predicted gravitational wave spectra in models with phase transitions?

Models of particle physics that feature phase transitions typically provide predictions for stochastic gravitational wave signals at future detectors and such predictions are used to delineate portions of the model parameter space that can be constrained. The question is: how precise are such predictions? Uncertainties enter in the calculation of the macroscopic thermal parameters and the dynamics of the phase transition itself. We calculate such uncertainties with increasing levels of sophistication in treating the phase transition dynamics. Currently, the highest level of diligence corresponds to careful treatments of the source lifetime; mean bubble separation; going beyond the bag model approximation in solving the hydrodynamics equations and explicitly calculating the fraction of energy in the fluid from these equations rather than using a fit; and including fits for the energy lost to vorticity modes and reheating effects. The lowest level of diligence incorporates none of these effects. We compute the percolation and nucleation temperatures, the mean bubble separation, the fluid velocity, and ultimately the gravitational wave spectrum corresponding to the level of highest diligence for three explicit examples: SMEFT, a dark sector Higgs model, and the real singlet-extended Standard Model (xSM). In each model, we contrast different levels of diligence in the calculation and find that the difference in the final predicted signal can be several orders of magnitude. Our results indicate that calculating the gravitational wave spectrum for particle physics models and deducing precise constraints on the parameter space of such models continues to remain very much a work in progress and warrants care.

Acoustic microstreaming near a plane wall due to a pulsating free or coated bubble: velocity, vorticity and closed streamlines

Acoustic microstreaming due to an oscillating microbubble, either coated or free, is analytically investigated. The detailed flow field is obtained and the closed streamlines of the ring vortex generated by microstreaming are plotted in both Eulerian and Lagrangian descriptions. Analytical expressions are found for the ring vortex showing that its length depends only on the separation of the microbubble from the wall and the dependence is linear. The circulation as a scalar measure of the vortex is computed quantitatively identifying its spatial location. The functional dependence of circulation on bubble separation and coating parameters is shown to be similar to that of the shear stress.

The Formation of a Dispersed Gas System in the Flotation Cells

The use of flotation methods for wastewater treatment is due to their advantages in comparison with other methods of gravity separation, for example, sedimentation. The advantages of flotation water treatment methods include the high speed of the separation process, the ability to extract impurities that are close in density to water, environmental friendliness. Flotation methods are based on adsorptive bubble separation processes. Accordingly, the performance of a particular flotator directly depends on the conditions for the implementation of these processes in a particular flotation cell. The aim of the research was to study the relationship between the dispersed gas phase (DGP) and the ratio of the geometric dimensions of the flotation cells based on the proposed shape indicator of the flotation cell. Studies performed on the experimental model of the flotator have established a significant influence of theshape indicator of the flotation cell on such important indicators of the adsorptive bubble separation processes as gas-filling and the DGP floating speed. The evaluation of different forms of flotation cells, in relation to the properties of extracted bubble-particle complexes is given.

Design and Testing of a Micro-Bubble Separation System

To support the broader development of isothermal compressor technology for natural gas systems, an experimental system has been designed and constructed to determine void fraction of a gas over time. The goal of this project was to determine how much time it takes for a gas, already statured in a working fluid, to separate from the working fluid. The result is a pressure vessel paired with a data acquisition system that could operate at a maximum of 3600 psi. A medium and high pressure system were designed, and the medium pressure system has been tested using visual methods.