Diffusion of deuterated poly(methyl methacrylate) (dPMMA) is slowed down in a PMMA matrix filled with hydroxyl-capped spherical silica nanoparticles, from 13 to 50 nm in diameter and at loadings up to 40 vol %. At constant T − T g = 75 K, the normalized diffusion coefficients (D/D 0 ) collapse onto a master curve, when plotted against the confinement parameter, ID/2R g , where ID is interparticle distance and 2R g is probe size. This result suggests that the confinement parameter captures the effect of nanoparticle size, size polydispersity, and volume fraction on polymer dynamics for the PMMA composite. For ID < 2R g , the master curve exhibits a strongly confined region where D/D 0 decreases by up to 80%, whereas for ID > 2R g , the curve falls in a weakly confined region where D/D 0 decreases only moderately by up to 15%. Surprisingly, D/D 0 is reduced even when ID is 8 times larger than 2R g . A comparison between the master curves for PMMA and polystyrene nanocomposites indicates that attractive interactions in the PMMA system do not significantly alter the centerof-mass diffusion of macromolecules in polymer nanocomposites.

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Dynamic properties play an important role in designing functional polymer nanocomposites, impacting molecular transport and phase separation kinetics. When nanoparticle (NP) size is comparable to polymer chain size, segmental relaxations may be influenced by changes in chain conformations and packing at the polymer/NP interface. Following the reptation model, these changes can perturb the longest relaxation time, in particular, the center-of-mass (COM) dynamics of polymer chains in entangled melts. This Perspective focuses on unsolved issues in polymer COM diffusion and local dynamics and segmental motions in the presence of NPs. The article introduces the effect of NP size, shape, surface modification, and enthalpic interactions on polymer diffusion and further relates dynamic studies in PNCs to macromolecular transport in bio-related systems and nanopores. Studies of local dynamics also provide insights into how entanglement density, monomeric friction, and chain conformation are influenced by NPs and how the interplay between these key parameters relates to COM dynamics to provide a unified picture across length scales. Moving forward, new studies investigating dynamics in PNCs are needed to address these unresolved problems and motivate potential applications from membranes for separations to NP carriers for drug delivery.

Novel earth-abundant metal sulfate-containing high entropy sulfides, FeNiCo-CrXS 2 (where X = Mn, Cu, Zn, or Al), are synthesized via a two-step solvothermal method. It is shown that sulfate-containing FeNiCoCrMnS 2 exhibits superior oxygen evolution reaction (OER) activity with an exceptionally low overpotential of 199, 246, 285, and 308 mV at current densities of 10, 100, 500, and 1000 mA cm -2 , respectively, and surpassing its unary-, binary-, ternary-, and quaternary-metal counterparts. The electrocatalyst yields exceptional stability after 12 000 cycles and 55 h of durability even at a high current density of 500 mA cm -2 . Various in situ and ex situ analyses are used to investigate the self-reconstruction of the sulfides during the OER for the first time. The resulting metal (oxy)hydroxide is believed to be the true active center for OER. The remaining sulfate also contributes to the catalytic activity. Density function theory calculation is in good agreement with the experimental result. The extraordinary OER performance of the high entropy sulfide brings a great opportunity for desirable catalyst design for practical applications.

The results can provide a direction for interventional studies designed to reduce the patients' fatigue.

This promising 25-item CKD-SE instrument can be used for the early identification of patients with low DSE, thus allowing the development of interventions to help these patients attain an appropriate level of DSE.

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