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This study proposes a multifunctional absorber in the terahertz (THz) regime based on vanadium dioxide (VO2) and graphene with either-or band selector applications, which can be realized by electrically and thermally controlling the Fermi energy level of graphene and vanadium dioxide, respectively. The broadband absorption can be achieved with absorptance exceeding 90%, when the VO2 film is in the metallic phase and the Fermi energy levels of the upper and lower graphene layers are simultaneously set to 0.6 and 0 eV, respectively. The double narrowband can be realized when the VO2 film is in the insulating phase and the Fermi energy levels in upper and lower graphene layers are set as 0 and 0.8 eV, respectively. By flexibly shifting between the broadband and the double narrowband, the proposed absorber can be used as an either-or band selector, corresponding optional bandwidth from 2.05 to 2.35 THz, and 3.25 to 3.6 THz. Furthermore, single narrowband absorption can be achieved by setting the conductivity of the VO2 film to appropriate values. The proposed absorber can be used in the THz regime in applications such as multifunctional devices, switches, cloaking objects, and band selectors.
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A broadband absorber based on metamaterials of graphene and vanadium dioxide (VO2) is proposed and investigated in the terahertz (THz) regime, which can be used for switch applications with a dynamically variable bandwidth by electrically and thermally controlling the Fermi energy level of graphene and the conductivity of VO2, respectively. The proposed absorber turns 'on' from 1.5 to 5.4 THz, with the modulation depth reaching 97.1% and the absorptance exceeding 90% when the Fermi energy levels of graphene are set as 0.7 eV, and VO2 is in the metallic phase. On the contrary, the absorptance is close to zero and the absorber turns 'off' with the Fermi energy level setting at 0 eV and VO2 in the insulating phase. Furthermore, other four broadband absorption modes can be achieved utilizing the active materials graphene and VO2. The proposed terahertz absorber may benefit the areas of broadband switch, cloaking objects, THz communications and other applications.
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BACKGROUND: The crystalline lens is a transparent structure of the eye to focus light on the retina. It becomes muddy, hard and dense with increasing age, which makes the crystalline lens gradually lose its function. We aim to develop a nuclear age predictor to reflect the degeneration of the crystalline lens nucleus. METHODS: First we trained and internally validated the nuclear age predictor with a deep-learning algorithm, using 12 904 anterior segment optical coherence tomography (AS-OCT) images from four diverse Asian and American cohorts: Zhongshan Ophthalmic Center with Machine0 (ZOM0), Tomey Corporation (TOMEY), University of California San Francisco and the Chinese University of Hong Kong. External testing was done on three independent datasets: Tokyo University (TU), ZOM1 and Shenzhen People's Hospital (SPH). We also demonstrate the possibility of detecting nuclear cataracts (NCs) from the nuclear age gap. FINDINGS: In the internal validation dataset, the nuclear age could be predicted with a mean absolute error (MAE) of 2.570 years (95% CI 1.886 to 2.863). Across the three external testing datasets, the algorithm achieved MAEs of 4.261 years (95% CI 3.391 to 5.094) in TU, 3.920 years (95% CI 3.332 to 4.637) in ZOM1-NonCata and 4.380 years (95% CI 3.730 to 5.061) in SPH-NonCata. The MAEs for NC eyes were 8.490 years (95% CI 7.219 to 9.766) in ZOM1-NC and 9.998 years (95% CI 5.673 to 14.642) in SPH-NC. The nuclear age gap outperformed both ophthalmologists in detecting NCs, with areas under the receiver operating characteristic curves of 0.853 years (95% CI 0.787 to 0.917) in ZOM1 and 0.909 years (95% CI 0.828 to 0.978) in SPH. INTERPRETATION: The nuclear age predictor shows good performance, validating the feasibility of using AS-OCT images as an effective screening tool for nucleus degeneration. Our work also demonstrates the potential use of the nuclear age gap to detect NCs.
Asunto(s)
Catarata , Cristalino , Humanos , Preescolar , Lactante , Cristalino/diagnóstico por imagen , Catarata/diagnóstico , Retina , Algoritmos , Tomografía de Coherencia Óptica/métodosRESUMEN
The aim of the present study was to elucidate the effect of resveratrol on nonalcoholic steatohepatitis (NASH), and the molecular basis in mice and Hepa16 cells, in order to verify its therapeutic effect. C57BL/6J mice were fed a methioninecholinedeficient (MCD) diet to induce steatohepatitis and were treated with resveratrol. Mouse sera were collected for biochemical analysis and enzymelinked immunosorbent assay, and livers were obtained for histological observation, and mmumicroRNA (miR)599 and inflammationrelated gene expression analysis. Hepa16 cells were treated with palmitic acid to establish a NASH cell model, and were then treated with resveratrol, or transfected with mmumiR599 mimic, mmumiR599 inhibitor or recombinant pregnane X receptor (PXR) plasmid. Subsequently, the cells were collected for mmumiR599 and inflammationrelated gene expression analysis. Reverse transcriptionquantitative polymerase chain reaction and western blotting were used to assess mmumiR599 expression levels, and the mRNA and protein expression levels of PXR and inflammationrelated genes. The binding site of mmumiR599 in the PXR mRNA was verified by the luciferase activity assay. Mice fed an MCD diet for 4 weeks exhibited steatosis, focal necrosis and inflammatory infiltration in the liver. Resveratrol significantly reduced serum aminotransferase and malondialdehyde levels, and ameliorated hepatic injury. These effects were associated with reduced mmumiR599 expression, enhanced PXR expression, and downregulated levels of nuclear factorκB, tumour necrosis factorα, interleukin (IL)1ß, IL6, NODlike receptor family pyrin domaincontaining protein 3 and signal transducer and activator of transcription 3. Administration of the mmumiR599 mimic inhibited PXR expression in Hepa16 cells, whereas the mmumiR599 inhibitor exerted the opposite effect. A binding site for mmumiR599 was identified in the PXR mRNA sequence. Furthermore, overexpression of PXR inhibited the expression of inflammatory factors in Hepa16 cells. The present study provided evidence for the protective role of resveratrol in ameliorating steatohepatitis through regulating the mmumiR599/PXR pathway and the consequent suppression of related inflammatory factors. Resveratrol may serve as a potential candidate for steatohepatitis management.