Conventional photodynamic therapy (PDT) uses red light for deeper penetration. A natural compound, aloe emodin (AE) with anticancer and photosensitising capabilities, excited by blue light, is proposed to treat superficial diseases. The photophysical properties and singlet oxygen quantum yield (Φ) of AE, as well as the cytotoxic effects of AE on human cells, were investigated. The absorption and emission spectra of AE were analyzed. The Φ of AE was measured by a relative method. In order to study the relationship between Φ and the oxygen concentration, the dependence of Φ on the oxygen concentration was investigated. The cytotoxic effects of AE alone and AE-mediated PDT were compared. The relationship between cells' survival rate and PDT conditions was studied. According to spectral analysis, the energy levels of AE were identified. The maximum absorption peak of AE is in the blue region, which makes AE-mediated PDT suitable for superficial diseases. The Φ of AE was determined to be 0.57(2), which was found to be dependent on the oxygen concentration. The studies under low oxygen concentration proved that there is no type I reaction between AE and the probe for singlet oxygen detection. The effect of AE-mediated PDT was significantly higher than that of AE alone and increased with the concentration of AE or fluence. AE-mediated PDT can provide a new strategy to treat superficial diseases using blue light, thus protecting deeper normal tissues.

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The influences of serrated trailing edge on the aerodynamic and aeroacoustic performance of a flapping wing during hovering flight are investigated using a hybrid framework of an immersed boundary Navier–Stokes solver for the flow field and the Ffowcs Williams–Hawkings (FW–H) analogy for the sound field. A rigid rectangular wing with an aspect ratio of 2 undergoes pitching and stroke motions at a Reynolds number (Re) of 310 and a Mach number (M) of 0.012. Simulations are conducted by varying the dimensionless wavenumber k* from 2π to 10π and wave amplitude 2h* from 0.25 to 1.0. We find that at k*=8π and 2h*=1.5 (D4), the average sound power level is reduced by up to 6.8 dB within the Strouhal number (St) between 2.0 and 4.0 compared to that of a plain trailing edge while the lift coefficient is maintained. The directivity at St = 0.2, St = 0.4, St = 2.2, and St = 2.4 is discussed. It is found that the serrations of D4 do not affect the directivity for the first two frequencies and significantly reduce the magnitude of the directivity for the last two frequencies. The serrations of D4 considerably alter the flow field near the wing surface and reduced the surface pressure fluctuations near the wing tip, leading to the noise reduction. The lift coefficient of D4 is not significantly changed, because the reduction in the pressure-contributed lift is compensated by an increase in the shear stress-contributed lift. The serrations with higher 2h* and k* have larger shear stress-contributed lift.