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Cavitation is usually divided into two classes of behavior. Inertial (or transient) cavitation is the process in which a void or bubble in a liquid rapidly collapses, producing a shock wave. It occurs in nature in the strikes of mantis shrimp and pistol shrimp, as well as in the vascular tissues of plants.
Microbubbles produced in the field oscillate and grow (due to factors including rectified diffusion), and can eventually implode (inertial or transient cavitation). During inertial cavitation, very high temperatures occur inside the bubbles, and the collapse during the rarefaction phase is associated with a shock wave and jets that can ...
Stable cavitation of intravascular microbubbles with FUS applies mechanical forces on BBB to increase permeability for drug delivery. Early studies that investigated the use of FUS for BBB disruption used ultrasound to increase the permeability of the blood vessels either by increasing the temperature (usually to 40-45°C) or forming gas bubbles (inertial cavitation).
Stable cavitation characterizes vapor bubbles that oscillate within its own equilibrium, while inertial cavitation describes bubbles that generate a net growth each time the bubble expands and results in the bubble collapsing violently. Severe cavitation increases the risk of damage to tissue and drug degradation.
Dimensionless numbers (or characteristic numbers) have an important role in analyzing the behavior of fluids and their flow as well as in other transport phenomena. [1] They include the Reynolds and the Mach numbers, which describe as ratios the relative magnitude of fluid and physical system characteristics, such as density, viscosity, speed of sound, and flow speed.
During these scale-up steps, it is essential to make sure that all local exposure conditions (ultrasonic amplitude, cavitation intensity, time spent in the active cavitation zone, etc.) stay the same. If this condition is met, the quality of the final product remains at the optimized level, while the productivity is increased by a predictable ...
In inertial cavitation, gas bubbles increase in volume and almost reach their resonance volume, swelling before aggressively collapsing. [1] The implosion of vesicles results in a drastic temperature and pressure change, thereby increasing the cell membrane's permeability to various drugs.
When using an ultrasound, cavities will develop due to the pressure change. Stable cavitation describes the repetitive oscillations of a cavity bubble, while inertial cavitation describes the collapse of a cavity bubble. [8] If the developed cavities fall apart, the effect on the stratum corneum lipids will increase the permeability of the skin.