Microbubbles disappearance

Once formed, a bubble nucleus is exceedingly stable.. ..There appears to be no time limit beyond which it is not possible to regenerate a bubble from a hydrophobic collapse site. In these experiments as much as 48 hours were permitted to elapse between bubble collapse and regeneration (ref. 84 cf. synthetic microbubble disappearance and formation in Section 10.4). 

The overheating effect is believed to play a dominant role in explaining the physical mechanism of the microbubble formation, and three main reasons could be underpinned First, it was observed that a small amount of the glycerin injected into the gap would eventually disappear after a few hours at the positive EEF intensity of 1 MV/cm. Second, no remarkable difference in the chemical composition between the glycerin before and after the EEF was applied could be found in the experiment, which indicated physical effects might predominate. Besides, a rough estimation of the temperature rise in the contact region due to the electro-thermal effect will be conducted as follows. 

Fig. 2. Microbubbles that are stabilized only with a mobile surfactant layer will fuse on contact and disappear - long term storage in the aqueous phase is not feasible...

SIZE DISTRIBUTION OF SYNTHETIC MICROBUBBLES FORMATION, COALESCENCE, FISSION, AND DISAPPEARANCE... 

Apparent reversible and/or cyclical behavior Microbubble formation and coalescence versus microbubble fission and disappearance... 

In the final series of measurements, a prolonged effort was made to record the cyclical process of microbubble forma-tion/coalescence/fission/disappearance in considerable detail. The... 

From the data presented in Chapter 10, it becomes evident that the extreme longevity of the artificial surfactant-stabilized microbubbles described therein is, in part, related to their continuous interaction with the simultaneously formed mixed micelle population in the saturated surfactant solution. More specifically, the surfactant-stabilized microbubbles produced by mechanical agitation of saturated solutions of either CAV-CON s Filmix 2 or Filmix 3 apparently undergo a cyclical (or reversible) process of microbubble formation/coalescence/fission/disappearance, where the end of each cycle is characterized by a collapse of the lipid-coated microbubbles into large micellar structures (i.e., rodlike multimolecular aggregates), only to re-emerge soon after as newly formed, lipid-coated microbubbles (see also below). 

S. Feinstein, K. Ong, Y. Fujibayashi, H. Standoff, W. Zwehl, S. Meerbaum, E. Corday and P. Shah, Myocardial contrast echo disappearance rate is related to size and uniformity of sonicated agent microbubbles, Clin. Res. 32 (1984) 163A. 

Fig. 7.5 P rinciple of SAE. Using high-amplitude sound pressure, the shell of the microcapsules breaks and the air bubble disintegrates rapidly. The sudden disappearance of the microbubble is misinterpreted by the ultrasound machine as a quick movement and color-coded in the image. This pseudo-Doppler effect is known as SAE.

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