Models of the formation of nanorolls in fluid media are constructed. The successive stages of the detachment of a stressed double nanolayer with the subsequent twisting into a nanoroll are calculated by the molecular dynamics method. The dynamics of twisting with the formation of a multiwalled nanoroll is described within a continuous model. The results of simulating the formation of different configurations of nanorolls during their diffusion growth are reported.

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Ultrasonic near-field levitation allows for contactless support and transportation of an object over vibrating surface. We developed an accurate model predicting pressure distribution in the gap between the surface and levitating object. The formulation covers a wide range of the air flow regimes: from viscous squeezed flow dominating in small gap to acoustic wave propagation in larger gap. The paper explains derivation of the governing equations from the basic fluid dynamics. The nonreflective boundary conditions were developed to properly define air flow at the outlet. Comparing to direct computational fluid dynamics modeling our approach allows achieving good accuracy while keeping the computation cost low. Using the model we studied the levitation force as a function of gap distance. It was shown that there are three distinguished flow regimes: purely viscous, viscoacoustic, and acoustic. The regimes are defined by the balance of viscous and inertial forces. In the viscous regime the pressure in the gap is close to uniform while in the intermediate viscoacoustic and the acoustic regimes the pressure profile is wavy. The model was validated by a dedicated levitation experiment and compared to similar published results.

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Experimental research into changes of the optical thickness of phenanthrenequinone-doped polymethyl methacrylate samples in the process of irradiation by a 473 nm laser is presented. It was demonstrated that heating-induced reversible changes lead to a decrease in the optical thickness. The temperature coefficient of the relative changes of the optical thickness was measured to be -1.40×10 К, which matches the data published by other authors. It is also established that the irreversible changes induced by the photochemical transformation lead to an increase in the optical thickness outside of the absorption band of the samples (λ>530  nm), where the relative change of which at λ=532  nm is +3.7×10. It was demonstrated that the reversible and irreversible changes do not compensate for each other in the process of sample exposure.