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The current study reports LaFe1-xMnxO3−δ redox catalysts (RCs) for CO2-splitting and methane partial oxidation (CH4-POx) in a cyclic redox scheme. Lanthanum (La) was chosen as the A-site cation whereas iron (Fe) and manganese (Mn) were chosen as the B-site cations, respectively. La, Fe, and Mn were incorporated into the perovskite structure (LaFe1-xMnxO3−δ) at various Fe/Mn ratios to tailor the equilibrium oxygen partial pressures for CO2-splitting and methane partial oxidation. Compared to the standalone redox pairs of Fe and Mn (i.e., Fe2O3/Fe3O4, Fe3O4/FeO, and Mn2O3/Mn3O4) which, from a thermodynamic standpoint, favor the complete combustion of CH4, the perovskite structured redox catalysts (RCs, i.e., LaFe1-xMnxO3−δ) favored the selective oxidation of CH4 to syngas. In addition, impregnating the RCs with 1 wt% ruthenium (Ru) led to a significant improvement in their redox kinetics without affecting their redox thermodynamics. The Ru-impregnated, perovskite structured RCs (i.e., LaFeO3, LaFe0.625Mn0.375O3, and LaFe0.5Mn0.5O3 ) exhibited excellent redox performance in terms of the syngas yield (92 – 100%) and CO2 conversion (95 - 98%). Long-term redox testing over Ru-impregnated LaFeO3 and LaFe0.5Mn0.5O3 demonstrated relatively stable performance for 100 redox cycles whereas activity loss was observed for LaFe0.625Mn0.375O3, LaFe0.375Mn0.625O3, and LaMnO3 respectively. Among RCs containing both Mn and Fe, LaFe0.5Mn0.5O3 exhibited the best performance, maintaining satisfactory activity over 100 cycles and higher oxygen capacity. XRD and XPS analysis suggest that the ability to regenerate the perovskite phase under a CO2 environment and a near surface A:B site cation ratio close to the perovskite stoichiometry would likely correspond to more stable performance. Additionally, the inclusion of Mn on the B-site enhances the coke resistance of the redox catalyst when compared to undoped LaFeO3. 

During plate convergence, shallow subduction or underthrusting of the lower-plate lithosphere beneath an overriding plate often results in far-field intraplate deformation, as observed in the Late Cretaceous–Paleogene North American Laramide or Cenozoic Himalayan-Tibetan orogen. Perplexingly, during this shallow-slab process, wide expanses of crust between the plate boundary and intraplate orogen do not experience significant synchronous deformation. These apparently undeformed crustal regions may reflect (1) a strong, rigid plate, (2) increased gravitational potential energy (GPE) to resist shortening and uplift, or (3) decoupling of the upper-plate lithosphere from any basal tractions. Here we review the geology of three orogens that formed due to flat slab subduction or underthrusting: the Himalayan-Tibetan, Mesozoic southeast China, and Laramide orogens. These orogens all involved intraplate deformation >1000-km from the plate boundary, large regions of negligible crustal shortening between the plate-boundary and intra-plate thrust belts, hot crustal conditions within the hinterland regions, and extensive upper-plate porphyry copper mineralization. A hot and weak hinterland is inconsistent with it persisting as an undeformed rigid block. GPE analysis suggests that hinterland quiescence is not uniquely due to thickened crust and elevated GPE, as exemplified by shallow marine sedimentation with low surface elevations in SE China. Comparison of these intracontinental orogens allows us to advance a general model, where hot orogenic hinterlands with a weak, mobile lower crust allow decoupling from underlying basal tractions exerted from flat-slab or underthrusting events. This hypothesis suggests that basal tractions locally drive intraplate orogens, at least partially controlled by the strength of the upper-plate lithosphere. 

A<sc>bstract</sc> The Energy Mover’s Distance (EMD) has seen use in collider physics as a metric between events and as a geometric method of defining infrared and collinear safe observables. Recently, the Spectral Energy Mover’s Distance (SEMD) has been proposed as a more analytically tractable alternative to the EMD. In this work, we obtain a closed-form expression for the Riemannian-likep= 2 SEMD metric between events, eliminating the need to numerically solve an optimal transport problem. Additionally, we show how the SEMD can be used to define event and jet shape observables by minimizing the distance between events and parameterized energy flows (similar to the EMD), and we obtain closed-form expressions for several of these observables. We also present the Specter framework, an efficient and highly parallelized implementation of the SEMD metric and SEMD-derived shape observables as an analogue of the previously-introduced Shaper for EMD-based computations. We demonstrate that computing the SEMD with Specter can be up to a thousand times faster than computing the EMD with standard optimal transport libraries.