The paper reports the results of nanotherapy of ovarian, breast, and pancreatic cancerous tumors by paclitaxel-loaded nanoemulsions that convert into microbubbles locally in tumor tissue under the action of tumor-directed therapeutic ultrasound. Tumor accumulation of nanoemulsions was confirmed by ultrasound imaging. Dramatic regression of ovarian, breast, and orthotopic pancreatic tumors was observed in tumor therapy through systemic injections of drug-loaded nanoemulsions combined with therapeutic ultrasound, signifying efficient ultrasound-triggered drug release from tumor-accumulated nanodroplets. The mechanism of drug release in the process of droplet-to-bubble conversion is discussed. No therapeutic effect from the nanodroplet/ultrasound combination was observed without the drug, indicating that therapeutic effect was caused by the ultrasound-enhanced chemotherapeutic action of the tumor-targeted drug, rather than the mechanical or thermal action of ultrasound itself. Tumor recurrence was observed after the completion of the first treatment round; a second treatment round with the same regimen proved less effective, suggesting that drug resistant cells were either developed or selected during the first treatment round.

The control algorithms used in high performance AC drives require the knowledge of rotor position and, in the case of speed regulation, also of speed. Since in many applications rotational transducers cannot be installed, their reconstruction is needed. The use of observers is stymied by the fact that the dynamics of electrical machines are highly nonlinear and does not belong to the class studied by the nonlinear control community. In this paper solutions to both problems, which are particularly tailored for the widely popular permanent magnet synchronous motors, 1 are provided. A key step for the design of both observers is the choice of a suitable set of coordinates. The position observer is a standard gradient search whose detailed analysis reveals outstanding (global asymptotic) stability properties. Furthermore, the analysis clearly exhibits the interplay between rotor speed and the gain of the gradient search-that (essentially) determines its convergence rate. The position observer is a simple two-dimensional nonlinear system, hence is easily implementable. The speed observer is designed following the immersion and invariance technique and is also shown to be globally convergent. Simulation and experimental results of the position observer, used together with a classical field-oriented control algorithm, are presented.

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The paper describes droplet-to-bubble transition in block copolymer stabilized perfluoropentane nanoemulsions. Three physical factors that trigger droplet-to-bubble transition in liquid emulsions and gels were evaluated, namely heat, ultrasound, and injections through fine-gauge needles. Among those listed, ultrasound irradiation was found the most efficient factor. Possible mechanisms of bubble generation and growth discussed in the paper include liquid-to-gas transition inside the individual bubble; bubble coalescence; and diffusion of dissolved air and/or perfluoropentane from small bubbles into larger bubbles (i.e., Oswald ripening). The last two factors result in irreversibility of the droplet-to-bubble transition. In gel matrices, ultrasound-induced droplet-to-bubble transition was substantially inhibited but was catalyzed by large (hundred micron) pre-existing bubbles irradiated by low frequency (hundred kilohertz) ultrasound. The dependence of the droplet-to-bubble transition on initial bubble size is theoretically treated and the role of increase of surface area in promoting bubble coalescence is discussed. Therapeutic implications of observed effects are discussed.

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