An integrated giant polyoxometalate complex for photothermally enhanced catalytic oxidation

A strategy integrating near infrared (NIR) photothermal and catalytic effects within one active center beyond ultraviolet and visible light is proposed without the combination of separated photothermal transformation components. A giant polyoxomolybdate, which has high NIR photothermal conversion efficiency, is selected as the model catalyst, while a cationic β-cyclodextrin is used to cover its negatively charged surface electrostatically. Under NIR light radiation, the designed catalyst increases catalytic activity of cyclohexene oxidation under O2 atmosphere in water. The conversion reaches about pentaploid of the reaction without NIR radiation. By excluding heating effect from the external heater at the same temperature, about twice as much enhancement, which can be attributed to the sole photothermal action, is still observed. While the catalytic center is shielded by the organic porous layer, the surface cavity allows the integrated catalyst to conduct a selective catalysis by screening the molecules in size over the surface channel.

Dimensional confinement and waveguide effect of Dyakonov surface waves in twisted confined media

We theoretically study Dyakonov surface waveguide modes that propagate along the planar strip interfacial waveguide between two uniaxial dielectrics. We demonstrate that owing to the one-dimensional electromagnetic confinement, Dyakonov surface waveguide modes can propagate in the directions that are forbidden for the classical Dyakonov surface waves at the infinite interface. We show that this situation is similar to a waveguide effect and formulate the resonance conditions at which Dyakonov surface waveguide modes exist. We demonstrate that the propagation of such modes without losses is possible. We also consider a case of two-dimensional confinement, where the interface between two anisotropic dielectrics is bounded in both orthogonal directions. We show that such a structure supports Dyakonov surface cavity modes. Analytical results are confirmed by comparing with full-wave solutions of Maxwell’s equations. We believe that our work paves the way toward new insights in the field of surface waves in anisotropic media.

Plugging slurry (backfill) and surface cavity closure technology

The purpose of the study is to study mining and environmental emergencies associated with the formation of sinkholes of the earth’s surface over mining workings after the mass closure of coal mines and to develop a new method for eliminating the sinkhole. The study used a method of physical modeling, which investigated the influence of humidity on the deformation properties of burnt rocks used as a filler in the manufacture of plugging and filling suspensions, while establishing the dependence of the relative deformation of dump rocks on the load at their natural humidity and water saturation. The main results of the research are: a new method for eliminating dips in the earth’s surface over the inclined opening workings of the liquidated coal mines of the Eastern Donbass; formulations of plugging and filling suspensions used for layer-by-layer filling of sinkholes and providing non-shrink laying.