Search results for "Microbubble"
showing 9 items of 29 documents
Slip Flow Over Structured Surfaces with Entrapped Microbubbles
2008
On hydrophobic surfaces, roughness may lead to a transition to a superhydrophobic state, where gas bubbles at the surface can have a strong impact on a detected slip. We present two-phase lattice Boltzmann simulations of a Couette flow over structured surfaces with attached gas bubbles. Even though the bubbles add slippery surfaces to the channel, they can cause negative slip to appear due to the increased roughness. The simulation method used allows the bubbles to deform due to viscous stresses. We find a decrease of the detected slip with increasing shear rate which is in contrast to some recent experimental results implicating that bubble deformation cannot account for these experiments.…
Effect of the anode composition on the performance of reversible chlor-alkali electro-absorption cells
2020
Abstract In this work, the performances of a reversible electrochemical cell for the storage of energy using the chloralkaline process was investigated. The cell operates at room temperature with liquid electrolytes in both compartments. In the electrolyzer mode, the cell transforms a sodium chloride solution into hydrogen and chlorine, which is then disproportionated to form hypochlorous acid and hypochlorite. In fuel cell operation mode, the cell becomes an electro-absorber to oxidize hydrogen at the anode while reducing hypochlorous acid at the cathode. Because of the low solubility of hydrogen, a special mechanical device is used to produce hydrogen microbubbles in the anodic compartmen…
Conical Fiber Probe for Mechanical Stabilization of Microbubbles in Liquids
2020
We demonstrate that a cone pierced in a fiber tip can stabilize microbubles photothermally generated in liquids. Bubbles can stand and monitor pressure shocks over 3.3 bar with a sensitivity below 7 mbar.
A Setup for Microscopic Studies of Ultrasounds Effects on Microliters Scale Samples: Analytical, Numerical and Experimental Characterization
2021
International audience; Sonoporation is the process of cell membrane permeabilization, due to exposure to ultrasounds. There is a lack of consensus concerning the mechanisms of sonoporation: Understanding the mechanisms of sonoporation refines the choice of the ultrasonic parameters to be applied on the cells. Cells’ classical exposure systems to ultrasounds have several drawbacks, like the immersion of the cells in large volumes of liquid, the nonhomogeneous acoustic pressure in the large sample, and thus, the necessity for magnetic stirring to somehow homogenize the exposure of the cells. This article reports the development and characterization of a novel system allowing the exposure to …
Sonoporation, a redefined ultrasound modality as therapeutic aid: a review.
2011
Traditionally a diagnostic modality, ultrasound is emerging as a promising tool for non-invasive therapy, drug delivery, and gene therapy. The ultrasound is a mechanical wave energy generated in a medium as oscillating pressure in space and time at frequencies above 20 kHz, beyond the audible range. The ultrasound exposure generates bioeffects resulting in tissue heating, shear stress, and cavitation, which have been exploited for therapeutic applications. Ultrasound cavitation, enhanced by injected micro bubbles, perturbs cell membrane structures to cause sonoporation and increases the permeability to bioactive materials. Ultrasound-mediated gene delivery has been applied to heart, blood v…
A versatile ultrasound system for in vitro experiments
2015
Objective One of the most difficult tasks to achieve with the available instrumentations used to study the interaction between ultrasound (US) and cellular model systems is to design an experiment, where only the effects of one physical parameter at a time is evaluated, while all the others are kept constant. The set-ups are usually custom-made, often by means of clinical instrument intended for a different therapeutic purpose. Furthermore, the results are not strictly comparable with others obtained with techniques considered standard in molecular and cellular biology at this time, because there is the need to use non-standard devices to contain biological samples. Sterility, as well as te…
New frontiers in liver ultrasound: From mono to multi parametricity
2021
Modern liver ultrasonography (US) has become a "one-stop shop " able to provide not only anatomic and morphologic but also functional information about vascularity, stiffness and other various liver tissue properties. Modern US techniques allow a quantitative assessment of various liver diseases. US scanning is no more limited to the visualized plane, but three-dimensional, volumetric acquisition and consequent post-processing are also possible. Further, US scan can be consistently merged and visualized in real time with Computed Tomography and Magnetic Resonance Imaging examinations. Effective and safe microbubble-based contrast agents allow a real time, dynamic study of contrast kinetic f…
Conic optical fiber probe for generation and characterization of microbubbles in liquids
2021
A novel optical fiber probe has been developed to provide mechanical stability to microbubbles generated in fluids, the tip of the fiber is etched with hydrofluoric acid to pierce a truncated horn that fastens the microbubbles to the fiber tip and prevents misalignment or detachment caused by convection currents, vibrations or shocks in the liquid. Microbubbles are photo-thermally generated on the etched fiber and used as Fabry-Perot cavity sensor. Two methods were used to interrogate the probe: the first one, in the wavelength domain, is suitable for calibration in static or quasi static situations; the second one, in the time domain, can be used in dynamic environments. Experimental resul…