Recently, the phenomena of streaming suppression and relocation of inhomogeneous miscible fluids under acoustic fields were explained using the hypothesis on mean Eulerian pressure. In this work, we derive the expression for the acoustic body force without relying on any prior assumptions regarding the second-order Eulerian pressure. We present a theory of nonlinear acoustics for inhomogeneous fluids from first principles, which explains streaming suppression and acoustic relocation in both miscible and immiscible inhomogeneous fluids inside a microchannel. This theory predicts the relocation of higher impedance fluids to pressure nodes of the standing wave, which agrees with recent experiments.
We present a technique for mixing the fluids in a microchannel using ultrasonic waves. Acoustic mixing is driven by the acoustic body force, which depends on the density gradient and speed of the sound gradient of the inhomogeneous fluid domain. In this work, mixing of fluids in a microchannel is achieved via an alternating multinode mixing method, which employs acoustic multinode standing waves of time-varying wavelengths at regular time intervals. The proposed technique is rapid, efficient, and found to enhance the mixing of fluids significantly. It is shown that the mixing time due to acoustic mixing (2–3 s) is reduced by two orders of magnitude compared to the mixing time only due to diffusion (400 s). Furthermore, we investigate the effects of the acoustic mixing on different fluid flow configurations and sound wave propagation directions as they have a direct influence on mixing time and have rarely been addressed previously. Remarkably, it is found that mixing performance is strongly dependent on the direction of the acoustic wave propagation. The acoustic field propagated parallel to the fluid-fluid interface mixes fluids rapidly (2–3 s) as compared to the acoustic field propagated perpendicular to the fluid-fluid interface (40 s).
To evaluate the repigmentation with non-cultured epidermal cell suspension followed by PUVA in patients with stable vitiligo. Materials and Methods: A prospective study conducted at the department of Dermatology, Venerology, Leprosy of Rajah Muthiah Medical College and Hospital. 26 cases of stable vitiligo were treated with non-cultured epidermal cell suspension followed by PUVA and were reviewed for a period of 20 weeks. Results: The results were assessed subjectively. 9 (34.6%) patients showed excellent response to our therapy, 7 (26.9%) patients had good response, 5 (19.3%) patients showed fair response and 3 (11.5%) showed very poor response. 17 (65%) patients showed a very good colour match when compared with the surrounding skin and 1 (3.8%) patients showed donor site scarring. Conclusion: Epidermal non cultured cell suspension followed by PUVA is a relatively safe method with superior quality of repigmentation.
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