All-inorganic metal halide perovskites of the formulation ABX (where A is Cs, B is commonly Pb, and X is a halide, X = Cl, Br, I) have been studied intensively for their unique properties. Most of the current studies focus on halogen exchange to modify the luminescence band gap. Herein we demonstrate a new avenue for changing the band gap of halide perovskites by designing mixed-monovalent cation perovskite-based colloidal quantum dot materials. We have synthesized monodisperse colloidal quantum dots of all-inorganic rubidium-cesium lead halide perovskites (APbBr, A = mixed monovalent cation systems Rb/Cs) using inexpensive commercial precursors. Through the compositional modulation, the band gap and emission spectra are readily tunable over the visible spectral range of 474-532 nm. The photoluminescence (PL) of RbCsPbBr nanocrystals is characterized with excellent (NTCS color standard) wide color gamut coverage, which is similar to the cesium lead halide perovskites (CsPbX, X = mixed halide systems Cl/Br), and narrow emission line-widths of 27-34 nm. Furthermore, simulated lattice models and band structures are used to explain the band gap variations.
Recent population studies provide clues that the use of curcumin may be associated with reduced incidence and improved prognosis of certain cancers. In the present study, we demonstrated that curcumin acted as a growth inhibitor for lung cancer cells. Our results found that curcumin inhibited cell proliferation, which was associated with upregulation of the cyclin-dependent kinase inhibitors, p27 and p21, and downregulation of cyclin D1. In addition, we showed that curcumin induced the expression of forkhead box protein O1 (FOXO1) through activation of extracellular signal-regulated kinase 1/2 signaling. These findings provide evidence for a mechanism that may contribute to the antineoplastic effects of curcumin and justify further work to explore potential roles for activators of FOXO1 in the prevention and treatment of lung cancer.
The transparent Er3+‐Yb3+‐doped fluoro‐aluminosilicate glass‐ceramic (GC) was prepared by melt‐quenching. The crystal phase, morphology, and up‐conversion (UC) luminescence of as‐produced GC were characterized by X‐ray diffraction, scanning electron microscopy, and fluorescence spectrophotometry, respectively. The results show that BaYF5 nanocrystals were uniformly distributed in the glass matrix of the as‐produced GC. When the as‐produced GC was subjected to heat treatment, the crystallinity was increased, but the crystal identity remains unchanged. Such heat‐treatment doubled the intensity of the UC luminescence, and this enhancement was ascribed to the increased incorporation of both Er3+ and Yb3+ ions into the lower phonon energy environment of BaYF5 nanocrystals. Furthermore, the heat‐treated GC was stable against further crystallization, and consequently its UC luminescence was stable at the application temperature. The heat‐treated GC was found to possess an outstanding temperature‐sensing capability.
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