Using extensive first-principles molecular dynamics calculations, we characterize the superionic phase transition and the lattice and electronic structures of the archetypal Type-I superionic conductor α-AgI. We find that superionicity is signalled by a phase transition of the silver ions alone. In the superionic phase, the first silver shell surrounding an iodine displays a distinct dynamical structure that would escape a time-averaged characterization, and we capture this structure in a set of ordering rules. The electronic structure of the system demonstrates a unique chemical signature of the weakest-bound silver in the first shell, which in turn is most likely to diffuse. Upon melting, the silver diffusion decreases, pointing to an unusual entropic contribution to the stability of the superionic phase.PACS numbers: 71.15. Pd,66.30.Dn Key advances in energy research have prompted a surge of interest in superionic materials, as a crucial enabling technology for a variety of nanotechnological devices, including sensors, switches, batteries, and fuel cells. Of the superionics, AgI and related silver halides and sulfides have attracted particular attention because of the unusually high levels of ionic conductivity they exhibit, and as such are finding increased and varied technological implementation [1,2,3]. At normal pressure, AgI enters its superionic α phase above T c = 420 K, at which temperature a phase transition to a body-centered cubic structure is accompanied by an increase in the silver conductivity of nearly three orders of magnitude, to a value of 1.31. Previous molecular dynamics studies using classical pair potentials have successfully reproduced experimental characteristics of the α and β phases, as well as the α → β transition [5,6,7,8,9,10], but these are unable to describe the electronic structure in a dynamic environment, or to capture the phenomenology of the melting transition. In this regard, first-principles simulations provide unique and unbiased predictive power.We perform Car-Parrinello molecular dynamics simulations in the canonical NVT ensemble at temperatures ranging from 200 K to 1250 K for a total of 800 ps. All simulations were performed with a 54-atom unit cell and a 0 = 5.174Å, except the Wannier function calculations, which were performed in a 32-atom unit cell [21].First, we find evidence of a phase transition of the silver ions near the experimental T c that is independent of the conformation and dynamics of the iodine sublattice and signals the transition into the superionic α phase. The silvers exhibit a sharp decrease in their diffusion behavior upon cooling below T c , although cubic boundary conditions forbid the iodine structural transition to the hexagonal wurtzite β phase. Results from a series of simulations in which we immobilized the iodines in a fixed bcc configuration provide a secondary, stronger indicator of the independence of the silver transition from any iodine dynamics. Fig. 1 displays the associated silver ion diffusion coefficients D Ag for the fixed...

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The ex-vivo assay is a sensitive and predictive model for assessing changes in heart function and biomarkers of toxicity and injury. This assay demonstrates the potential for sunitinib and sorafenib to cause cardiac toxicity in humans. Also, TNFα appears to be a biomarker in the heart prior to injury. Due to its versatility, the isolated heart assay has potential to fill gaps in cardiac safety testing early in drug development.