Two-dimensional (2D) carbon allotrope called penta-graphene was recently proposed from first-principles calculations and various similar penta-structures emerged. Despite significant effort having been dedicated to electronic structures and mechanical properties, little research has been focused on thermal transport in penta-structures. Motivated by this, we performed a comparative study of thermal transport properties of three representative pentagonal structures, namely penta-graphene, penta-SiC2, and penta-SiN2, by solving the phonon Boltzmann transport equation with interatomic force constants extracted from first-principles calculations. Unexpectedly, the thermal conductivity of the three penta-structures exhibits diverse strain dependence, despite their very similar geometry structures. While the thermal conductivity of penta-graphene exhibits standard monotonic reduction by stretching, penta-SiC2 possesses an unusual nonmonotonic up-and-down behavior. More interestingly, the thermal conductivity of penta-SiN2 has 1 order of magnitude enhancement due to the strain induced buckled to planar structure transition. The mechanism governing the diverse strain dependence is identified as the competition between the change of phonon group velocity and phonon lifetime of acoustic phonon modes with combined effect from the unique structure transition for penta-SiN2. The disparate thermal transport behavior is further correlated to the fundamentally different bonding nature in the atomic structures with solid evidence from the distribution of deformation charge density and more in-depth molecular orbital analysis. The reported giant and robust tunability of thermal conductivity may inspire intensive research on other derivatives of penta-structures as potential materials for emerging nanoelectronic devices. The fundamental physics understood from this study also solidifies the strategy to engineer thermal transport properties of broad 2D materials by simple mechanical strain.

Objective: Cervical carcinoma (CC) is a serious threat to women's health and few effective therapeutic methods have been discovered. The purpose of this study is to explore the underlying mechanism of miR-145-5p in CC. Methods: Bioinformatics methods were employed to analyze the gene expression data of CC from TCGA database. qRT-PCR was used to detect the expression of miR-145-5p and KLF5 in CC cells, and Western blot was employed for the examination of KLF5 protein level. The targeted relationship between miR-145-5p and KLF5 was verified by a dualluciferase reporter assay. Moreover, CCK-8, wound healing assay and transwell invasion assay were used to analyze the effects of miR-145-5p overexpression or KLF5 silencing on the proliferation, migration and invasion of CC cells. Results: miR-145-5p was shown to be down-regulated in CC tissues and cells, while KLF5 was up-regulated. miR-145-5p could bind to the complementary sequence within the wild type KLF5 3ʹUTR rather than the mutant one. In addition, miR-145-5p could effectively down-regulate KLF5, in turn inhibiting the proliferation, migration and invasion of CC cells. Conclusion: miR-145-5p regulates the proliferation, migration and invasion of CC cells by targeting KLF5.

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Two-dimensional (2D) pentagonal monolayer structures have shown promising characteristics and fascinating physical and chemical properties. The disparate strain-dependent thermal conductivity of two-dimensional penta-structures was reported, but the difference between the silicon-based pentagonal and hexagonal structures is barely researched. In this work, based on first-principles calculations, we studied the strain-modulated phonon transport behavior of two 2D pentagonal (penta-SiH and bilayer penta-Si) and one hexagonal silicene structures (H-silicene), of which the penta-SiH and H-silicene mean the structures are hydrogenated for the purpose of thermodynamical stability. We found that the silicon-based pentagonal structure also presented a different strain-dependent thermal conductivity from other pentagonal materials, such as penta-graphene, penta-SiC, or penta-SiN. Moreover, even with the similar strain-dependent thermal transport behavior in penta-SiH and bilayer penta-silicene, we find that the governing mechanism is still different. For both pentagonal silicene structures, the thermal conductivity presents a large improvement at first as the tensile strain increases from 0 to 10% and then stabilizes with a strain larger than 10%. A detailed analysis shows that the in-plane modes contributed the most part to the group velocity enhancement under strains in penta-SiH which is opposite from the bilayer penta-graphene, although the phonon group velocity and phonon lifetime of both structures increase with applied strain. On the other hand, a similarity was found in pentagonal silicene and hexagonal silicene despite the differences in geometry structures. Furthermore, based on the detailed analysis between the pentagonal (penta-SiH) and hexagonal silicene structures (H-silicene), the difference in out-of-plane phonon scattering cannot be ignored: different major scattering channels of the out-of-plane flexural modes result in different thermal conductivity sensitivity to strains, and the disparity in anharmonicity leads to different thermal conductivity under no strain.