This study reframes interventions in short-form video recommendations as an operational decision-making problem. Specifically, it examines when and how strongly platforms should engage with users after periods of inactivity. It compares state-aware and state-agnostic intervention strategies using two real-world datasets: KuaiRand-1 K (1000 users, approximately 11.7 million interactions) and KuaiRand-Pure (approximately 27,000 users, 1.4 million interactions). The evaluation focused on process-level exploration indicators, namely, TimeShare and StepShare rather than traditional click-through or consumption metrics. The results indicate that state-aware interventions are associated with an earlier and more pronounced reallocation of exploration within sessions. For example, in KuaiRand-1 K, following a short period of inactivity, the state-aware intervention increased TimeShare from 0.060 to 0.084 (approximately 40%) and StepShare from 0.413 to 0.436. Under longer inactivity conditions, the TimeShare increased from 0.091 to 0.106 (approximately 16%). Further analysis showed that process-level changes persisted even at lower intervention intensities. Taken together, these findings suggest that state-contingent intervention policies can systematically reshape the exploration dynamics of short-form video recommendations.
This study aims to analyze the regeneration of Mo/HZSM-5 catalysts deactivated during shale gas dehydroaromatization, with a focus on the apparent kinetics of coke removal. Thermogravimetric analysis and single--particle kinetic modeling were employed to estimate reaction rate constants under varying O2 concentrations, temperatures, and particle sizes. The model successfully predicted the time required for coke elimination across different pellet diameters. Experimental results showed that coke was completely removed at high O2 concentrations; however, the activity of Mo2C active sites was not restored due to dealumination and the formation of Al2(MoO4)3. To ensure stable regeneration, O2 concentration and flow rate were optimized to control heat release. Long-term cycle tests demonstrated that regeneration at 1.5% O2 provided better catalyst stability than at 10%. Finally, the developed coke-removal model was applied to fixed-bed, moving-bed, and fluidized-bed reactor configurations, revealing differences in allowable O2 concentration, temperature profiles, and coke removal rates depending on gas/solid flow patterns. This work uniquely integrates kinetic modeling with stability evaluation, offering practical guidelines for selecting regeneration strategies across reactor types.
Electrochemical CO2 reduction (CO2R) powered with renewable electricity has been considered as a promising approach for carbon emission mitigation and sustainable production of value-added chemicals. Developing active and selective electrocatalysts capable of achieving high multi-carbon product selectivity at low overpotentials remains a critical challenge. In this work, we develop a lanthanum (La) doping strategy to optimize Cu-based catalysts for enhanced CO2R performance. As a result, the optimized La-modified CuO catalyst achieves a remarkable Faradaic efficiency of over 75% toward multi-carbon products at a modest potential of approximately -0.5 V versus reversible hydrogen electrode, achieving a practical relevant current density of over 200 mA cm(-2). This high selectivity represents a twofold enhancement over state-of-the-art CuO-based catalysts under identical conditions. Detailed kinetic assessments and mechanistic investigations reveal that La incorporation enhance *CO binding strength on Cu and facilitate CO-CO dimerization, thereby facilitating the production of multi-carbon products. Overall, this work establishes an effective approach for boosting multi-carbon production through strategic rare-earth element modification, thereby advancing the development of efficient CO2R systems for sustainable chemical synthesis.image
Despite significant advances in nonlinear optical (NLO) materials, a systematic strategy for designing mid-infrared (mid-IR) NLO oxides that simultaneously exhibit strong second-harmonic generation (SHG) efficiency and wide optical transparency remains elusive. Herein, we report two polar antiperovskite oxide materials, (Pb1.5Cd1.5)GeO5 (PCGO) and Pb3GeO5 (PGO). Structural analyses reveal that PCGO adopts a 2H-hexagonal antiperovskite structure, whereas PGO features a three-dimensional antiperovskite framework. Both materials are thermally stable up to approximately 900 degrees C and exhibit wide optical transparency extending into the mid-IR region (0.3-13 mu m). Powder SHG measurements indicate that PCGO and PGO exhibit strong SHG efficiencies of 0.5 and 1.3 times that of AgGaS2, respectively, along with particle-size-dependent SHG responses indicative of phase-matching behavior. Further first-principles calculations reveal moderate birefringence values of 0.053 and 0.058 at 1064 nm for PCGO and PGO, respectively, corresponding to shortest phase-matching (PM) wavelengths of 737 and 776 nm. A closer structural investigation and density functional theory calculations suggest that the pronounced distortions of OPb/Cd6 and OPb6 octahedra, together with highly polarizable cations, play a dominant role in governing the SHG responses. These results highlight polar antiperovskite oxides as a promising platform for the development of next-generation mid-IR NLO materials.
Suppressing dark current while enhancing photocurrent remains a key challenge in organic photodiodes (OPDs). Planar heterojunction (PHJ) OPDs offer low dark current and high phase stability but often suffer from low photocurrent. Here, we present perfluoroarene-based spacer layers-2PFB, 4PFB, and 6PFB-as a strategy to simultaneously improve exciton dissociation efficiency (eta ed) and charge transfer state dissociation efficiency (eta cd). These spacers enhance interfacial band-bending, boosting eta cd with minimal eta ed loss. The optimized ITO/HAT-CN/TPD/SubPc/6PFB(4 nm)/C60/Bphen/Al OPD achieves a peak external quantum efficiency (EQE) over 70%. The method is compatible with various donors when favorable Fermi level alignment is present. Furthermore, monolithic integration of 6PFB-based OPDs on CMOS readout circuits yielded a 77.9% increase in sensitivity, confirming their practical viability. This approach offers a generalizable, effective pathway to overcoming the EQE-photocurrent trade-off in PHJ OPDs, representing a significant advancement toward high-performance, commercially viable organic photodetectors.
