Just for the sake of the phrases “rejuvenating glass” and “Jovian planets”, …

I am linking to these two papers in the latest PNAS:

[1] Spatiotemporal structures in aging and rejuvenating glasses

W G Peter

Complex spatiotemporal structures develop during the process of aging glasses after cooling and of rejuvenating glasses on heating. The key to understanding these structures is the interplay between the activated reconfiguration events that generate mobility and the transport of mobility. These effects are both accounted for by combining the random first-order transition theory of activated events with mode coupling theory in an inhomogeneous setting. The predicted modifications by mobility transport of the time course of the aging regime are modest. In contrast, the rejuvenation process is strongly affected through the propagation of fronts of enhanced mobility originating from the initial reconfiguration events. The structures in a rejuvenating glass resemble flames. An analysis along the lines of combustion theory provides an estimate of the front propagation speed. Heterogeneous rejuvenation naturally should occur for glasses with free surfaces. The analogy with combustion also provides a way of looking at the uptake of diluents by glasses described by case II and super case II diffusion.

[2] Phase separation in hydrogen–helium mixtures at Mbar pressures

M A Morales et al

The properties of hydrogen–helium mixtures at Mbar pressures and intermediate temperatures (4000 to 10000 K) are calculated with first-principles molecular dynamics simulations. We determine the equation of state as a function of density, temperature, and composition and, using thermodynamic integration, we estimate the Gibbs free energy of mixing, thereby determining the temperature, at a given pressure, when helium becomes insoluble in dense metallic hydrogen. These results are directly relevant to models of the interior structure and evolution of Jovian planets. We find that the temperatures for the demixing of helium and hydrogen are sufficiently high to cross the planetary adiabat of Saturn at pressures ≈5 Mbar; helium is partially miscible throughout a significant portion of the interior of Saturn, and to a lesser extent in Jupiter.

The MD study, by the way, is an Open Access article. Have fun!


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