RESUMEN
Further optimization of perovskite light-emitting diodes (PeLEDs) is impeded by crystal deformation caused by residual stress and defect formation with subsequent non-radiative recombination. Molecular additives for defect passivation are widely studied; however, the majority have insulating properties that hinder charge injection and transport. Herein, highly efficient green-emitting PeLEDs are reported by introducing semiconducting molecular additives (Fl-OEGA and Fl-C8A). Transmission electron microscopy shows that conjugated additives exist primarily at the grain boundaries of perovskite, and Kelvin probe force microscopy confirms that the variation in contact potential difference between grain boundaries and perovskite crystal domains is significantly reduced. The residual tensile stress is reduced by 13% and the activation energy for ion migration increases in the Fl-OEGA-treated perovskite film, compared to those of the film without additives. Compared to insulating 2,2'-(ethylenedioxy)diethylamine (EDEA), the introduction of semiconducting additives prevents a significant reduction in the charge-transport capability. Furthermore, the PeLEDs with Fl-OEGA show a negligible shift in the turn-on voltage and a significantly smaller decrease in the current density with increasing Fl-OEGA compared to the devices with EDEA. Finally, the 3D CsPbBr3 -PeLEDs show the highest external quantum efficiency of 21.3% by the incorporation of semiconducting Fl-OEGA as a new multifunctional additive.
RESUMEN
This study describes the development of a landslide monitoring system for the purpose of reducing damages caused by landslides in natural terrain. The system was developed to analyze the effects of landslide-inducing rainfall and the behavior of slopes through 12 monitoring stations that are distributed across eight national parks in Korea. Several sensors and a data acquisition equipment to monitor landslide were installed in each station. The composition of the system and its operating program were designed to efficiently manage the sizeable amounts of real-time monitoring data that are collected from the various stations. To test the potential of the developed system for reliable landslide hazard evaluations, data measured over a five-year period by the two monitoring stations in Jirisan National Park were analyzed. Subsequently, the suction stress of the soil over the monitoring period was calculated by applying laboratory test result of the geotechnical and unsaturated soil properties in the analysis domain area. The infinite slope stability analysis combined with an effective stress concept based on the suction stress was applied to calculate the factor of safety. This method also enabled the temporal and quantitative evaluation of slope stability in natural terrain. In addition, based on the monitoring and slope stability analysis results, an analysis for the spatial classification of landslide hazards was conducted. The analysis results quantitatively and statistically demonstrated that 98% of historical landslide initiation areas were classified as high hazard levels.
RESUMEN
The objective of this study was to investigate the behavior of zinc incorporation into newly forming fuel deposits and pre-formed deposits in a simulated pressurized water reactor coolant including 1000 ppm of boron and 2 ppm of lithium at 328 °C. Zinc was incorporated into fuel deposits that were being newly nucleated and grown on nuclear fuel cladding tubes in a zinc-containing coolant. The zinc incorporation resulted in a decrease in the lattice constant of the deposits, which was attributed to the decrease in larger iron content and the corresponding incorporation of smaller zinc in the deposits. However, zinc incorporation was not found, even after the fuel deposits pre-formed before zinc addition were subsequently exposed to the 60 ppb of zinc coolant for 500 h.
RESUMEN
A high-quality perovskite film is a key aspect contributing to high photovoltaic performance of all-inorganic perovskite solar cells. We herein demonstrate that the addition of methylammonium iodide (MAI) influences effectively both the tailored film morphology and precise crystal growth to construct high-quality CsPbI2Br films. It is found that an MAI additive retards the crystallization kinetics to control the inorganic perovskite films to form a highly crystalline α-CsPbI2Br structure consisting of microsized grains with reduced defect density. The optimal MAI additive (10 wt %) achieves a power conversion efficiency (PCE) of 10.40% for the CsPbI2Br-based all-inorganic perovskite solar cells, which is >30% enhancement from 6.95% of the pristine one. The solar cells employing the MAI additive possess high operational and thermal stability, retaining >70% of the original PCE after aging for 1500 h in ambient atmosphere and under continuous heating at 85 °C for 30 h, respectively. The photovoltaic performance with an indoor light source was also examined using a white light-emitting diode (6500 K, 1000 lux), showing promising PCEs of 23.51% with a stabilized power output of 21.15%.
RESUMEN
Macrophage-associated inflammation is crucial for the pathogenesis of diverse diseases including metabolic disorders. Rhodanthpyrone (Rho) is an active component of Gentiana rhodantha, which has been used in traditional Chinese medicine to treat inflammation. Although synthesis procedures of RhoA and RhoB were reported, the biological effects of the specific compounds have never been explored. In this study, the anti-inflammatory activity and mechanisms of action of RhoA and RhoB were studied in lipopolysaccharide (LPS)-stimulated macrophages. Pretreatment with RhoA and RhoB decreased inducible nitric oxide synthase and cyclooxygenase-2 expressions in RAW 264.7 cells and in thioglycollate-elicited mouse peritoneal macrophages. In addition, it downregulated transcript levels of several inflammatory genes in LPS-stimulated RAW 264.7 cells, including inflammatory cytokines/chemokines (Tnfa, Il6, and Ccl2) and inflammatory mediators (Nos2 and Ptgs2). Macrophage chemotaxis was also inhibited by treatment with the compounds. Mechanistic studies revealed that RhoA and RhoB suppressed the nuclear factor (NF)-κB pathway, but not the canonical mitogen activated protein kinase pathway, in LPS-stimulated condition. Moreover, the inhibitory effect of RhoA and RhoB on inflammatory gene expressions was attenuated by treatment with an NF-κB inhibitor. Our findings suggest that RhoA and RhoB play an anti-inflammatory role at least in part by suppressing the NF-κB pathway during macrophage-mediated inflammation.