Multilayer hexagonal boron nitride (h-BN) is highly desirable as a dielectric substrate for the fabrication of two-dimensional (2D) electronic and optoelectronic devices. However, the controllable synthesis of multilayer h-BN in large areas is still limited in terms of crystallinity, thickness and stacking order. Here, we report a vapor-liquid-solid growth (VLSG) method to achieve uniform multilayer h-BN by using a molten Fe 82 B 18 alloy and N 2 as reactants. Liquid Fe 82 B 18 not only supplies boron but also continuously dissociates nitrogen atoms from the N 2 vapor to support direct h-BN growth on a sapphire substrate; therefore, the VLSG method delivers high-quality h-BN multilayers with a controllable thickness. Further investigation of the phase evolution of the Fe-B-N system reveals that isothermal segregation dominates the growth of the h-BN. The approach herein demonstrates the feasibility for large-area fabrication of van der Waals 2D materials and heterostructures.

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Increasing evidence showed that circular RNAs (circRNAs) play critical roles in tumorigenesis. However, the roles and underlying mechanisms of circRNAs in clear cell renal cell carcinoma (ccRCC) remain unclear. In the present study, we identified a novel circRNA circPCNXL2, which was significantly upregulated in ccRCC by circular RNA microarray. Further analysis revealed that circPCNXL2 was significantly increased and correlated with poor overall survival of ccRCC patients. Function assays revealed that circPCNXL2 knockdown reduced RCC cells proliferation, invasion in vitro, and decreased tumor growth in vivo. In mechanism study, we showed that circPCNXL2 could be bind to miR-153 as a miRNA sponge to regulate ZEB2 expression in RCC progression. In addition, our data reported that the effects of circPCNXL2 inhibition on RCC cells proliferation and invasion could be abolished by miR-153 inhibitors. Altogether, we demonstrated that circPCNXL2 could regulate RCC cells proliferation and invasion by miR-153/ZEB2 axis, suggesting circPCNXL2 might serve as a potential therapeutic target for ccRCC treatment.