2Spatial phase inhomogeneity at the nano-to microscale is widely observed in stronglycorrelated electron materials. The underlying mechanism and possibility of artificially controlling the phase inhomogeneity are still open questions of critical importance for both the phase transition physics and device applications. Lattice strain has been shown to cause the coexistence of metallic and insulating phases in the Mott insulator VO 2 . By continuously tuning strain over a wide range in single-crystal VO 2 micro-and nanobeams, here we demonstrate the nucleation and manipulation of one-dimensionally ordered metal-insulator domain arrays along the beams. Mott transition is achieved in these beams at room temperature by active control of strain. The ability to engineer phase inhomogeneity with strain lends insight into correlated electron materials in general, and opens opportunities for designing and controlling the phase inhomogeneity of correlated electron materials for micro-and nanoscale device applications. 3Correlated Electron Materials (CEMs) offer a wide spectrum of properties featuring various types of phase transitions, such as superconductivity, metal-insulator transition, and colossal magnetoresistance 1 . A spatial phase inhomogeneity or micro-domain structure is frequently observed in these materials 2 , where multiple physical phases co-exist at the nano-to microscale at temperatures where a pure phase is expected. Despite decades of investigation, the question of whether the phase inhomogeneity is intrinsic or caused by external stimuli (extrinsic) still remains largely unanswered. This question not only plays a critical role in our understanding of the CEM physics, but also directly determines the spatial scale of CEM device applications.Lattice strain, if tuned continuously, would be a sensitive means to shed light on the origin of the phase inhomogeneity. In contrast to conventional materials, where elastic deformation causes continuous, minor variations in material properties, lattice strain has profound influence on the electrical, optical, and magnetic properties of CEMs through coupling between the charge, spin, and orbital degrees of freedom of electrons 3 . If phase inhomogeneity is absent in strain-free, single-crystal specimens, but can be introduced and modulated by external strain, it would then be possible to eliminate or strain engineer the inhomogeneity and domains in CEMs for nanoscale device applications. Previous strain studies of CEMs have been limited to epitaxial thin films. Biaxial strain imposed from lattice mismatch with the substrate has been shown to remarkably enhance the order parameters in ferroelectric 4-6 and high-Tc superconducting epilayers 7 . In these films the lattice-mismatch strain distribution is complicated by misfit dislocations. In contrast, free-standing, single-crystal CEM nanostructures are dislocation-free, and can be subjected to coherent and continuously tunable external stress. CEM phase transitions and domain dynamics can then be explored through in s...
Key Words Osteoarthritis • LPS-induced injury • LncRNA GAS5 • Kruppel-like factor 2 • NF-κB and Notch pathwaysAbstract Background/Aims: Osteoarthritis (OA) is the most frequently occurring joint disease and characterized by degeneration of cartilage. As the unique cell type in cartilage, chondrocytes play a crucial role during OA. Our study explored the influence of long non-coding RNA (lncRNA) growth arrest-specific transcript 5 (GAS5) on lipopolysaccharides (LPS)-induced injury in ATDC5 cells. Methods: Cell viability, apoptosis and expression of inflammatory cytokines were all assessed to evaluate LPS-induce inflammatory injury. Expression of GAS5 in LPS-induced cells was evaluated by qRT-PCR. After cell transfection, effect of abnormally expressed GAS5 on LPS-induced inflammatory injury was determined. Then, the possible target of GAS5 was screened by bioinformatics and verified by qRT-PCR and luciferase activity assay. Together, whether aberrant expression of target gene affected the modulation of GAS5 in LPS-induced inflammatory injury was also assessed. Finally, the influences of aberrant expressed Kruppel-like factor 2 (KLF2) on nuclear factor κB (NF-κB) and Notch pathways were detected by Western blot analysis. Results: LPS reduced cell viability and promoted cell apoptosis and secretion of inflammatory cytokines, along with down-regulation of GAS5. LPS-induced injury was alleviated by GAS5 overexpression while was exacerbated by GAS5 silence. KLF2 was predicted and verified as a target of GAS5, and GAS5 functioned through regulating expression of KLF2. Besides, aberrant expression of KLF2 regulated expressions of key kinases involved in the NF-κB and Notch pathways. Conclusion: GAS5 might ameliorate LPS-induced inflammatory injury in ATDC5 chondrocytes by inhibiting the NF-κB and Notch signaling pathways.
As the most abundant internal modification in eukaryotic cells, N6-methyladenosine (m6A) in mRNA has shown widespread regulatory roles in a variety of physiological processes and disease progressions. Circular RNAs (circRNAs) are a class of covalently closed circular RNA molecules and play an essential role in the pathogenesis of various diseases. Recently, accumulating evidence has shown that m6A modification is widely existed in circRNAs and found its key biological functions in regulating circRNA metabolism, including biogenesis, translation, degradation and cellular localization. Through regulating circRNAs, studies have shown the important roles of m6A modification in circRNAs during immunity and multiple diseases, which represents a new layer of control in physiological processes and disease progressions. In this review, we focused on the roles played by m6A in circRNA metabolism, summarized the regulatory mechanisms of m6A-modified circRNAs in immunity and diseases, and discussed the current challenges to study m6A modification in circRNAs and the possible future directions, providing a comprehensive insight into understanding m6A modification of circRNAs in RNA epigenetics.
We investigated external-stress-induced metal-insulator phase transitions in cantilevered single-crystal VO 2 nanobeams at variable temperatures using a combined theoretical and experimental approach. An atomic force microscope was used to measure the force-displacement curve of the nanobeams, which showed nonlinearity that signifies activation and expansion of domains of a new phase out of the old one. Superelasticity of the VO 2 nanobeam and supersaturation of the phase transition were clearly observed and quantified within the general theory of first-order phase transitions. Phase field modeling was employed to understand the energetics of the domain formation.
Transmissible gastroenteritis virus (TGEV) and porcine epidemic diarrhea virus (PEDV) are similar coronaviruses, causing diseases characterized by vomiting, diarrhea, and death from severe dehydration in piglets. Thus, they have caused huge losses to the swine-breeding industry worldwide. Nowadays, they are easily transmitted among the continents via vehicles, equipment, and cargo. Both viruses establish an infection in porcine enterocytes in the small intestine, and their spike (S) proteins play a key role in the virus-cell binding process under unfavorable conditions when the intestine with a low pH is filled with a thick layer of mucus and proteases. Sialic acid, proteases, and low pH are three main inducers of coronavirus infection. However, the details of how sialic acid and low pH affect virus binding to the host cell are not determined, and the functions of the proteases are unknown. This review emphasizes the role of three factors in the invasion of TGEV and PEDV into porcine enterocytes and offers more insights into Alphacoronavirus infection in the intestinal environment.
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