Metal halide perovskites have received much attention for their application in light-emitting diodes (LEDs) in the past several years. Rapid progress has been made in efficient green, red, and near-infrared perovskite LEDs. However, the development of blue perovskite LEDs is still lagging far behind. Here, we report efficient sky-blue perovskite LEDs by rearranging low-dimensional phase distribution in quasi-2D perovskites. We incorporated sodium ions into the mixed-Cl/Br quasi-2D perovskites with phenylethylammonium as the organic spacer and cesium lead halide as the inorganic framework. The inclusion of the sodium ion was found to significantly reduce the formation of the n = 1 phase, which was dominated by nonradiative transition, and increase the formation of other small-n phases for efficient exciton energy transfer. By managing the phase distribution, a maximum external quantum efficiency (EQE) of 11.7% was achieved in the sky-blue perovskite LED, with a stable emission peak at 488 nm. Further optimizing the phase distribution and film morphology with Pb content, we demonstrated the sky-blue devices with the average EQE approaching 10%. This strategy of engineering phase distribution of quasi-2D perovskites with a sodium ion could provide a useful way for the fabrication of high-performance blue perovskite LEDs.

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A CO2-free electrosynthesis of ammonia from air and water is presented with a solid Fe2O3 catalyst confined to activated charcoal.

Formamidinium lead bromide (FAPbBr3) nanocrystals (NCs) demonstrate great potential in light‐emitting diode (LED) applications due to their pure green emission and excellent stability. However, the abundant defects at the surface of the NCs act as charge trapping centers and significantly increase the trap‐assisted nonradiative recombination channels, hampering the performance improvement of LEDs based on FAPbBr3 NCs. Herein, a facile self‐passivation strategy of the surface defects is developed by introducing excess formamidinium bromide (FABr) during the colloidal synthesis of NCs, leading to much improved photoluminescence quantum yield (PLQY) of the obtained NCs. In addition, enhanced charge transport property is measured in the assembled films owing to the simultaneously declined insulating ligands at the surface of NCs. The molar ratio of FABr and PbBr2 is rationally optimized during the synthesis of NCs and high‐efficient green‐emissive LEDs are fabricated with a champion current efficiency of 76.8 cd A−1, corresponding to an external quantum efficiency of 17.1%, which is among the best‐performing green LEDs based on perovskite NCs so far.

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Gene expression analysis of The Cancer Genome Atlas (TCGA) breast cancer data set show that miR-20a is upregulated in human breast cancer, especially in triple-negative subtype. Gene Set Enrichment Analysis suggests that miR-20a expression negatively correlates with the autophagy/lysosome pathway. We report here that miR-20a inhibits the basal and nutrient starvation-induced autophagic flux and lysosomal proteolytic activity, increases intracellular reactive oxygen species levels and DNA damage response by targeting several key regulators of autophagy, including BECN1, ATG16L1 and SQSTM1. Re-introduction of exogenous BECN1, ATG16L1 or SQSTM1 reverses the inhibitory effect of miR-20a on autophagy and decreases DNA damage. A negative correlation between miR-20a and its target genes is observed in breast cancer tissues. Lower levels of BECN1, ATG16L1 and SQSTM1 are more common in triple-negative cancers than in other subtypes. High levels of miR-20a also associate with higher frequency of copy-number alterations and DNA mutations in breast cancer patients. Further studies in a xenograft mouse model show that miR-20a promotes tumor initiation and tumor growth. Collectively, these findings suggest that miR-20a-mediated autophagy defect might be a new mechanism underlying the oncogenic function of miRNA during breast tumorigenesis.

Autophagy plays an important role in plant-pathogen interactions. Several pathogens including viruses induce autophagy in plants, but the underpinning mechanism remains largely unclear. Furthermore, in virusplant interactions, viral factor(s) that induce autophagy have yet to be identified. Here, we report that the βC1 protein of Cotton leaf curl Multan betasatellite (CLCuMuB) interacts with cytosolic glyceraldehyde-3phosphate dehydrogenase (GAPC), a negative autophagic regulator, to induce autophagy in Nicotiana benthamiana. CLCuMuB βC1 bound to GAPCs and disrupted the interaction between GAPCs and autophagyrelated protein 3 (ATG3). A mutant βC1 protein (βC1 3A) in which I45, Y48, and I53 were all substituted with alanine (A), had a dramatically reduced binding capacity with GAPCs, failed to disrupt the GAPCs-ATG3 interactions and failed to induce autophagy. Furthermore, mutant virus carrying βC1 3A showed increased symptoms and viral DNA accumulation associated with decreased autophagy in plants. These results suggest that CLCuMuB βC1 activates autophagy by disrupting GAPCs-ATG3 interactions.