A test of climate, sun, and culture relationships from an 1810-year Chinese cave record.

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Emission thermal quenching is commonly observed in quasi-2D perovskite emitters, which causes the severe drop in luminescence efficiency for the quasi-2D perovskite light-emitting diodes (PeLEDs) during practical operations. However, this issue is often neglected and rarely studied, and the root cause of the thermal quenching has not been completely revealed now. Here, we develop a passivation strategy via the 2,7-dibromo-9,9-bis (3′-diethoxylphosphorylpropyl)-fluorene to investigate and suppress the thermal quenching. The agent can effectively passivate coordination-unsaturated Pb2+ defects of both surface and bulk of the film without affecting the perovskite crystallization, which helps to more truly demonstrate the important role of defects in thermal quenching. And our results reveal the root cause that the quenching will be strengthened by the defect-promoted exciton-phonon coupling. Ultimately, the PeLEDs with defect passivation achieve an improved external quantum efficiency (EQE) over 22% and doubled operation lifetime at room temperature, and can maintain about 85% of the initial EQE at 85 °C, much higher than 17% of the control device. These findings provide an important basis for fabricating practical PeLEDs for lighting and displays.

Cisplatin resistance has long been a major problem that restricts its use. A novel paradigm in tumor biology suggests that gastric tumor chemo-resistance is driven by gastric cancer stem cell-like (GCSCs). Growing evidence has indicated that microRNAs (miRNAs) contributes to chemo-resistance in gastric cancer (GC). Here, Lgr5 cells derived from gastric cancer cell lines displayed stem cell-like features. Flow cytometry demonstrated the presence of a variable fraction of Lgr5 in 19 out of 20 GC specimens. By comparing the miRNA expression profiles of Lgr5 GCSCs and Lrg5 cells, we established the upregulation of miR-132 in Lgr5 GCSCs. The enhanced miR-132 expression correlated chemo-resistance in GC patients. Kaplan-Meier survival curve showed that patients with low miR-132 expression survived obviously longer. Functional assays results indicated that miR-132 promoted cisplatin resistance in Lgr5 GCSCs in vitro and in vivo. Further dual-luciferase reporter gene assays revealed that SIRT1 was the direct target of miR-132. The expression of miR-132 was inversely correlated with SIRT1 in gastric cancer specimens. Furthermore, through PCR array we discovered ABCG2 was one of the downstream targets of SIRT1. Overexpression of SIRT1 down-regulated ABCG2 expression by promoting the de-acetylation of the transcription factor CREB. CREB was further activated ABCG2 via binding to the promoter of ABCG2 to induce transcription. Thus, we concluded that miR-132 regulated SIRT1/CREB/ABCG2 signaling pathway contributing to the cisplatin resistance and might serve as a novel therapeutic target against gastric cancer.

Additives play a critical role for efficient perovskite light-emitting diodes (PeLEDs). Here, we report a novel phosphonate/phosphine oxide dyad molecular additive (PE-TPPO), with unique dual roles of passivating defects and enhancing carrier radiative recombination, to boost the device efficiency of metalhalide perovskites. In addition to the defect passivation effect of the phosphine oxide group to enhance the photoluminescence intensity and homogeneity of perovskite film, the phosphonate group with strong electron affinity can capture the injected electrons to increase local carrier concentration and accelerate the carrier radiative recombination in the electroluminescence process. Owing to their synergistic enhancement on device efficiency, quasi-two-dimensional green PeLEDs modified by this dyad additive exhibit a maximum external quantum efficiency, current efficiency, and power efficiency of 25.1 %, 100.5 cd A À 1 , and 98.7 lm W À 1 , respectively, which are among the reported state-of-the-art efficiencies.

Cisplatin resistance in colorectal cancer largely results from the colorectal cancer stem cells which could be targeted to improve the efficacy of chemotherapy. MicroRNAs are possible modulators of cancer stem cell characteristics and maybe involved in the retention of cancer stem cell chemoresistance. The aim of this study was to investigate the biological function of miR-199a/b on cisplatin resistance in colorectal cancer stem cells and its related mechanisms. Here, ALDHA1 cells from primary colorectal cancer tissues behaved similar to cancer stem cells and were chemoresistant to cisplatin. The presence of a variable fraction of ALDHA1 was detected in 9 out of 10 colorectal cancer specimens. Significantly, increased miR-199a/b expression was detected in ALDHA1 colorectal cancer stem cells, accompanied by a downregulation of Gsk3β and an overexpression of β-catenin and ABCG2. In patient cohort, enhanced miR-199a/b expression in colorectal cancer tissues was associated with cisplatin response and poor patient survival. In addition, 80% of colorectal cancer samples showed lower level of Gsk3β than their adjacent normal counterparts. Furthermore, Gsk3β was the direct target of miR-199a/b. MiR-199a/b regulated Wnt/β-catenin pathway by targeting Gsk3β in ALDHA1 colorectal cancer stem cells. By blocking Wnt/β-catenin pathway, we implied that ABCG2 lies downstream of Wnt/β-catenin pathway. ABCG2 was further demonstrated to contribute cisplatin resistance in ALDHA1 colorectal cancer stem cells and can be regulated by miR-199a/b. Thus, our data suggested that upregulation of miR-199a/b in ALDHA1 colorectal cancer stem cells contributed to cisplatin resistance via Wnt/β-catenin-ABCG2 signaling, which sheds new light on understanding the mechanism of cisplatin resistance in colorectal cancer stem cells and facilitates the development of potential therapeutics against colorectal cancer.

Quasi-2D perovskites with enlarged exciton binding energy and tunable bandgap are appealing for application in perovskite light-emitting diodes (PeLEDs). However, wide n domains distribution is commonly formed in solution-processed quasi-2D perovskite films due to the uncontrollable crystallization behavior, which leads to low device performance. Here, the crystallization process is successfully regulated to narrow the n domains distribution by introducing compound additive of ZrO 2 nanoparticles (NPs) and Cryptand complexant. ZrO 2 NPs can avoid the segregation of organic large and small cations by strengthening the solvent extraction capacity of antisolvent, while Cryptand offsets the poor solubility of PbBr 2 by forming an intermediate state to slow down the crystallization of high-n domains. Consequently, both high photoluminescence quantum yields over 90% and a high external quantum efficiency of 21.2% are obtained in the optimized green quasi-2D PeLEDs. Moreover, the lifetime extends about four times compared with control devices. The strategy of domain controlling by compound additive provides a powerful way to develop high-performance quasi-2D perovskite optoelectrical devices.