RESUMEN
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.
RESUMEN
Health risks and hazards caused by the environment have long been one of the most important public issues of concern to the state, society, and the public. At the same time, population aging is becoming a global issue, and residents' health is the most important component of people's livelihood, and residents can only pursue other rights and interests if they can protect their own health. Therefore, based on the micro data from the fifth round of the China Family Panel Studies (CFPS), this paper uses binary logistic regression with propensity score matching (PSM) to analyze the effect of environmental perception on the health status (including mental health and physical health) of middle-aged and older adults. It was found that environmental perceptions significantly affect the depressive state and sickness status of middle-aged and older adults. Among them, middle-aged and older adults who were female, of rural households, with low education and relatively low income were more affected by environmental shocks on their health. Therefore, we should pay attention to the mental and physical health of middle-aged and older adults and change the existing design concept of aging policy: the government should formulate effective policies and increase corresponding social support; and society and families should also give corresponding care and encourage middle-aged and older adults to exercise more and provide reasonable psychological guidance.
Asunto(s)
Envejecimiento , Estado de Salud , Persona de Mediana Edad , Humanos , Femenino , Anciano , Masculino , Apoyo Social , China/epidemiología , PercepciónRESUMEN
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 dual-luciferase 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 3'UTR 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.