Cancer stem‐like cells (CSC) or cancer‐initiating cells are now considered to be an important cell population related to cancer recurrence and the resistance to anti‐cancer therapy. Tumor‐associated macrophages (TAM) are a main component of stromal cells and are related to cancer progression in clear cell renal cell carcinoma (ccRCC). Because the detailed mechanisms allowing the maintenance of CSC in cancer tissues remain unclear, we investigated the relationship between TAM and CD44‐expressing cancer cells in ccRCC. CD44 was used as a marker for CSC, and CD163 and CD204 were used as markers for TAM. CD44‐positive cancer cells were detected in 37 of the 103 cases. Although statistical analysis showed no relationship between CD44‐positive cancer cells and the clinical course, the distribution of CD44‐positive cancer cells was significantly associated with a high density of TAM. Our in vitro study using RCC cell lines and human macrophages demonstrated that CD44 expression was upregulated by direct co‐culture with macrophages. Silencing of TNF‐alpha on macrophages abrogated the upregulation of CD44 expression in cancer cells. Macrophage‐induced CD44 overexpression was also suppressed by NF‐κB inhibitors. These results suggest that TNF‐alpha derived from TAM is linked to CD44 overexpression via NF‐κB signaling in ccRCC.
2D/3D perovskite heterostructure solar cells are promising for their stability and high power conversion efficiency (PCE). However, organic cations in the horizontally oriented 2D perovskite inhibit carrier transport, and thus, PCE is markedly suppressed when the 2D perovskite is thickened to improve stability. In this study, the orientation control of 2D perovskite on 3D perovskite was realized to overcome the tradeoff between stability and PCE of 2D/3D heterostructure. 2D perovskite fabricated on (110)-oriented MAPbI 2.5 Cl 0.5 was horizontally oriented to the substrate surface. In contrast, 2D perovskite fabricated on ( 200)/(112)-oriented MAPbI 3 was obliquely oriented at 45°to the substrate surface. The change of orientation angle in 2D perovskite strongly depended upon the predominant crystal orientation of 3D perovskite template. The tolerance of lattice matching between 3D and 2D perovskite must allow the orientation control. This work provides a universal strategy to improve the stability of perovskite solar cells demonstrating the high PCE.
Thin films of a typical organic–inorganic halide perovskite material, CH3NH3PbI3 (MAPbI3), were fabricated by a bar-coating method, which is one of the candidate techniques for large-scale production. The film thickness of MAPbI3 markedly changed depending on the sweep speed of the coating bar, that is, it decreased in evaporation regime under the low-speed condition, and increased in the Landau–Levich regime under the high-speed condition. The typical inverted-type p-i-n planar solar cells with the MAPbI3 thin films demonstrated the photoelectric conversion efficiency of 14.0%, and their photovoltaic properties depending on the sweep speed were discussed by taking the surface morphology and crystallinity into consideration.
2D/3D perovskite heterostructure solar cells with orientation controlled 2D perovskite were realized. The obliquely and horizontally oriented Dion-Jacobson (DJ) 2D perovskites were fabricated by templated growth onto (200)/(112)-oriented MAPbI3 and (110)-oriented MAPbI2Br, respectively. The obliquely oriented 2D perovskite exhibited the excellent carrier transport properties, while the horizontally oriented 2D perovskite inhibited the carrier transport and drastically deteriorated the solar cell performances. In addition, the 2D/3D heterostructure solar cell with obliquely oriented DJ 2D perovskite demonstrated the enhanced stability. The excellent carrier transport properties of orientation-controlled 2D perovskite would contribute to the 2D/3D heterostructure solar cells with high stability and performance.
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