Dissipative self-assembly is a challenging but attractive field of supramolecular science, because it generally concerns complex system but is more close to the self-assembly of living bodies. We successfully realized dissipative self-assembly by coupling a supra-amphiphile with a chemical oscillator.
Porous monoliths of MoO3 nanoplates were synthesized from ammonium molybdate (AHM) by freeze-casting and subsequent thermal treatment from 300 to 600 °C. Pure orthorhombic MoO3 phase was obtained at thermal treatment temperature of 400 °C and above. MoO3 monoliths thermally treated at 400 °C displayed bimodal pore structure, including large pore channels replicating the ice crystals and small pores from MoO3 sheets stacking. Transmission electron microscopy (TEM) images revealed that the average thicknesses of MoO3 sheet were 50 and 300 nm in porous monoliths thermally treated at 400 °C. The photocatalytic performance of MoO3 was evaluated through degradation of methylene blue (MB) under visible light radiation and MoO3 synthesized at 400 °C exhibited strong adsorption performance and best photocatalytic activity for photodegradation of MB of 99.7% under visible illumination for 60 min. MoO3 photocatalyst displayed promising cyclic performance, and the decolorization efficiency of MB solution was 98.1% after four cycles.
Spiral waves composed of coherent traveling waves surrounding a core containing stochastically distributed stationary areas are found in numerical simulations of a three-variable reaction-diffusion system with one diffusible species. In the spiral core, diffusion of this component (w) mediates transitions between dynamic states of the subsystem formed by the other two components, whose dynamics is more rapid than that of w. Diffusive coupling between adjacent sites can be "on" or "off" depending on the subsystem state. The incoherent structures in the spiral core are produced by this decoupling of the slow diffusive component from the fast non-diffusing subsystem. The phase diagram reveals that the region of incoherent behavior in chimera spirals grows drastically, leading to modulation and breakup of the spirals, in the transition zones between 1(n-1) and 1(n) local mixed-mode oscillations.
Based upon a former study, the chlorite-trithionate reaction can avoid the side reactions arising from the well-known alkaline decomposition of polythionates, making it a suitable candidate for investigating spatial front instabilities in a reaction-diffusion-convection system. In this work, the chlorite-trithionate reaction was investigated in a Hele-Shaw cell, in which fingering patterns were observed over a wide range of reactant concentrations. A significant density increment crossing the propagating front indicates that the fingering pattern is generated as a consequence of the buoyancy-driven instability due to the density changes of solute when the gap thickness is less than 4 mm. The velocity of the steepest descent in the propagating front depends almost linearly on the gap thickness but displays a saturation-like profile on the trithionate concentration as well as a maximum on the chlorite concentration. Numerical simulation using the Stokes-Brinkman Equation coupled to the reaction-diffusion processes, including hydrogen ion autocatalysis and consumption, reproduces the observed fingering fronts.
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