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Apoptosis-induced Proliferation in UV-Irradiated Human Conjunctival Epithelial Cells
摘要： A pterygium is a benign growth that develops on the conjunctiva and, in some cases, extends to the cornea and interferes with vision. Excessive exposure to ultraviolet (UV) light is one of the causes of pterygium development. We previously reported that UV-induced apoptosis is led by production of reactive oxygen species (ROS) that activate p38 mitogen-activated protein kinase (MAPK) in human conjunctival epithelial (HCE) cells. Also, ROS-dependent induction of interleukin-11 (IL-11) has been reported to upregulate MAPK pathways, which results in compensatory proliferation. In this study, we examined the effect of UV exposure on HCE cells, in terms of change in apoptosis, ROS generation, phosphorylation of c-Jun N-terminal kinase (JNK), levels of IL-11 (a key cytokine in tissue repair and compensatory proliferation), production of activator protein 1 (AP-1), and expression of c-myc, c-fos and c-jun (which provides evidence of healthy cell proliferation). Apoptosis in HCE cells was induced by UV light irradiation (312 nm, 4.94 mW/cm2). Apoptosis was measured using the Muse Annexin V and Dead Cell Assay Kit. ROS generation was measured by using 5-(and 6-) chloromethyl-2?7?-dichlorodihydrofluorescein diacetate, acetyl ester. JNK phosphorylation, IL-11 levels and AP-1 production were measured by enzyme-linked immunosorbent assays (ELISAs). Imnunocytochemical staining was used to measure c-myc, c-fos and c-jun expression. UV irradiation increased ROS generation, phosphorylation of JNK, and apoptotic cell count. IL-11 levels and AP-1 production were significantly increased by UV irradiation. The irradiated cells had increased expression of c-myc, c-fos and c-jun, and treatment of the cells with IL-11 significantly increased expression of c-myc, c-fos and c-jun. These results suggest that the release of IL-11 from UV-induced apoptotic HCE cells and surrounding healthy cells could promote proliferation to maintain homeostasis.
关键词： conjunctiva,compensatory proliferation,apoptosis,interleukin-11 (IL-11),Ultraviolet (UV)
更新于2025-09-23 15:22:29
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Reproducing the a??Framinga?? by a Sequential Stress Test
摘要： The “Framing” (local discoloration along cell edges) was induced by a simple sequential accelerated stress test (consisting of hygrothermal- and UV-stressors) applied to the PV modules with high OTR (oxygen transmission rate) backsheet, irrespective of the inclusion of UV-absorber in poly(ethylene-co-vinyl acetate) (EVA) encapsulant. UV-fluorescence imaging of the PV modules suggests that the spatially-inhomogeneous degradation of EVA material under UV-irradiating conditions is correlated to this “Framing” indicating an underlying common mechanism. These findings would contribute to the development of test procedures to broadly mimic the actual failures observed in fielded PV.
关键词： snail trail,metallization,framing,photovoltaic (PV) module,ultraviolet (UV)-induced degradation
更新于2025-09-23 15:21:01
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Novel ultraviolet photodetector with ultrahigh photosensitivity employing SILAR-deposited ZnS film on MgZnO
摘要： A novel MgZnO/ZnS heterojunction-based ultraviolet (UV) photodetector (PD) with high performance is fabricated by a facile sol-gel process and a successive ionic layer adsorption and reaction (SILAR) method. ZnS is coated onto the MgZnO film as an interface modification layer, which overcomes the drawbacks of the pristine MgZnO photosensitive layer, such as lower carrier mobility and more traps in the material, and greatly enhances UV-light absorption. The type-II heterostructure constructed by work function differences near the interface facilitate the separation of photogenerated carriers. Compared with the MgZnO PD, the optimized heterojunction PD (MgZnO/ZnS-10) yields a dramatically decreased dark current (z1 nA), a remarkable responsivity (900 A/W) and an ultrahigh photo-to-dark current ratio (up to 2.3 (cid:1) 105) under 325 nm light illumination at 5 V bias. These results provide a cost-efficient means for improving the properties of MgZnO PDs, and show the advantages of MgZnO/ZnS heterojunction PDs in UV detection. This study demonstrates that rational construction of novel heterojunctions holds great potential for fabricating high-performance photodetectors.
关键词： Type-II heterostructure,MgZnO,Ultraviolet (UV) photodetector (PD),ZnS
更新于2025-09-23 15:19:57
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Performance analysis of p-LPZO/n-GZO and p-SZO/n-GZO homojunction UV photodetectors
摘要： A comprehensive analytical model for the dark current and photoresponsivity of ZnO thin film based homojunction ultraviolet (UV) photodetector (PD) is proposed in this study. The detailed insight about the effects of different acceptor doping materials in the illuminated surface layer is presented in this work. The recombination velocity of the carriers and the effect of applied reverse bias, specifically on the responsivity of p-n homojunction based UV PD are elucidated. The impact of two different types of dual ion beam sputtering (DIBS)-grown acceptor-doped ZnO (Sb:ZnO and Li-P:ZnO) materials on the responsivity is also discussed. The investigation results reveal that an increase in applied reverse bias results in higher responsivity due to depletion region increase leading to higher charge carrier photogeneration. Further, on comparing the results with the experimentally reported ZnO-based homojunction UV PDs, it is found that, by incorporating Sb:ZnO as p-type layer, dark current and responsivity values are improved by ~38 and ~63.7%, respectively. Hence, the developed model is significant for the design optimization of high-performance ZnO thin film-based UV homojunction PDs.
关键词： Dual ion beam sputtering (DIBS),Responsivity,Photodetector (PD),Ultraviolet (UV)
更新于2025-09-23 15:19:57
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Room-temperature processed ZrO2 interlayer towards efficient planar perovskite solar cells
摘要： The Sn-doped In2O3 transparent conductive (ITO) electrode in planar perovskite solar cells (PSCs) is modified by zirconia (ZrO2) interlayer with low-temperature process. Here the ZrO2 film is prepared by ultraviolet (UV) treatment at room temperature. The effects of the inserted ZrO2 interlayer on the performance of CH3NH3PbI3-xClx-based PSCs have been systemically studied. After optimizing the process, the champion efficiency of PSC with UV-treated ZrO2 interlayer is 19.48%, which is larger than that of the reference PSC (15.56%). The improved performance in the modified devices is primarily ascribed to the reduced trap states and the suppressed carrier recombination at the ITO/SnO2 interface. Our work provides a facile route to boost the photovoltaic performance of PSCs by modifying the surface of transparent conductive electrode at room temperature.
关键词： Photoelectric properties,ITO/SnO2 interface modification,Ultraviolet (UV) treatment,Planar perovskite solar cell,Room-temperature processed ZrO2 interlayer
更新于2025-09-19 17:13:59
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A 4H-SiC UV Phototransistor With Excellent Optical Gain Based on Controlled Potential Barrier
摘要： In this article, we report the experimental results of a visible-light-blind 4H-polytype silicon carbide phototransistor able to detect ultraviolet (UV) radiations for wavelengths lower than 380 nm with a significative improvement in the optical gain compared with the state-of-the-art of 4H-SiC UV phototransistors. From the electro-optical measurements, the device shows a dark current of 0.62 pA, an ON-/OFF-current ratio of seven orders of magnitude up to bias voltage of ?0.5 V, and an excellent optical gain of 1.14·105 at 300 nm, whereas it is only 2.6·10?3 at 400 nm demonstrating a good rejection of visible radiations. Besides having high optical gain, the phototransistor is also more sensitive than the conventional 4H-SiC UV detectors for wavelengths with low penetration depths, because its structure is designed to have the electric field up to the radiated surface where the photogenerated electron–hole pairs are efficiently swept up before recombination occurs. The operating principle of the detector is also investigated, and we experimentally proved that differently from the conventional 4H-SiC bipolar junction transistor phototransistor, it is based on the change in the potential barrier height, which controls the current flow, due to the variation in the Fermi levels when the electron–hole pairs are photogenerated. A comparison with the state-of-the-art of 4H-SiC UV phototransistors is reported.
关键词： 4H-SiC semiconductor device,phototransistor,potential barrier,ultraviolet (UV) detector,electro-optical characterization
更新于2025-09-12 10:27:22
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ZnO nanorods array as light absorption antenna for high-gain UV photodetectors
摘要： Hydrothermal method provides the advantages of simple, low-temperature growth conditions, low cost and large surface areas for the samples. Also, exciton dissociation can be enhanced by surface plasmon resonance (SPR) due to the plasmonic absorption enhancement of incident light. In this paper, high-gain ultraviolet (UV) photodetectors based on vertically aligned ZnO nanorods (ZnO-NRs) array as light absorption antenna were presented, in which ZnO-NRs array was prepared by hydrothermal method. Our experimental data showed that the device performance of the UV photodetector Au/ZnO(ZnO-NRs:Au-NPs)/Au can be further enhanced after the gaps of ZnO-NRs array were filled with Au nanoparticles (Au-NPs). The photo-to-dark current ratio and the specific detectivity of the UV photodetector Au/ZnO(ZnO-NRs:Au-NPs)/Au reached to 1×105 and 1.84×1013 Jones at 2 V under 100 μW/cm2 365 nm illumination, respectively. The physical mechanism for the enhanced performance of the UV photodetectors is discussed.
关键词： Surface plasmon resonance (SPR),ZnO nanorods (ZnO-NRs) array,Ultraviolet (UV) photodetectors,Hydrothermal method,Schottky contact
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - High-Efficiency, All-Dielectric Metasurfaces Down to the Deep Ultraviolet
摘要： In recent years, researchers have demonstrated various types of high-performance, all-dielectric metasurfaces operating in the infrared (IR) and visible regimes, paving the way towards high-efficiency, multi-functional and compact photonic systems. However, there has been a conspicuous lack of research on metasurfaces designed for operation in the ultraviolet (UV) region, which is the spectral region hosting various important applications such as photolithography, spectroscopy, astronomy, medical therapy, and high-resolution imaging. Unfortunately, direct scaling of the operation frequencies of metasurfaces based on the IR and visible designs down to the UV is challenging, due to the prohibitively high optical loss of typically employed constituent materials (e.g., Si, TiO2, GaN). Here, we report on low-loss, all-dielectric metasurfaces operating at UV wavelengths down to the deep-ultraviolet range. The metasurface are based on Hafnium Oxide (HfO2), an amorphous dielectric material most commonly exploited as a high static dielectric constant (high-k) material in integrated circuit fabrication, that is characterized by a wide-bandgap (5.8 eV). We develop a unique Damascene fabrication process, involving both low-temperature atomic layer deposition (ALD) of HfO2 onto patterned resist and back etching with Argon ion milling, to achieve high-aspect-ratio HfO2 nanostructures with straight and smooth sidewall profiles (Fig. 1a). We demonstrate a variety of polarization-independent UV metasurface devices having distinct functionalities, namely diffraction-limited focusing lenses (metalenses), hologram projectors (metaholograms) and self-accelerating beam generators, operating at two near-UV wavelengths (364 and 325 nm) with efficiencies as high as 75%. As an example, the measured intensity distribution for a NA=0.6 metalens operating at 325 nm reveals lensing with a circularly symmetric focal spot (Fig. 1b), of first-dark-ring diameter close to the theoretical diffraction-limited value. Scaling down metasurface critical dimensions, we achieve metaholograms (Fig. 1c) operating with high efficiencies at a record-short, deep-UV wavelength of 266 nm. The captured image for such a metahologram operating at 266 nm (Fig. 1d) demonstrates holographic projection with a measured efficiency of 60%. Finally, we demonstrate 266-nm, spin-multiplexed metasholograms of greater degree of geometric complexities, with efficiencies up to 61%. Our work paves the way towards compact and multifunctional UV flat optical systems.
关键词： deep ultraviolet,UV wavelengths,high-efficiency,all-dielectric metasurfaces,photonic systems
更新于2025-09-12 10:27:22
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Deep UV plasmonic enhancement of single protein autofluorescence in zero-mode waveguides
摘要： Single molecule detection provides detailed information about molecular structures and functions, but it generally requires the presence of a fluorescent marker which can interfere with the activity of the target molecule or complicate the sample production. Detecting a single protein with its natural UV autofluorescence is an attractive approach to avoid all the issues related to fluorescence labelling. However, the UV autofluorescence signal from a single protein is generally extremely weak. Here, we use aluminum plasmonics to enhance the tryptophan autofluorescence emission of single proteins in the UV range. Zero-mode waveguides nanoapertures enable observing the UV fluorescence of single label-free β-galactosidase proteins with increased brightness, microsecond transit times and operation at micromolar concentrations. We demonstrate quantitative measurements of the local concentration, diffusion coefficient and hydrodynamic radius of the label-free protein over a broad range of zero-mode waveguide diameters. While the plasmonic fluorescence enhancement has generated a tremendous interest in the visible and near-infrared parts of the spectrum, this work pushes further the limits of plasmonic-enhanced single molecule detection into the UV range and constitutes a major step forward in our ability to interrogate single proteins in their native state at physiological concentrations.
关键词： plasmonics,ultraviolet UV,single molecule fluorescence,nanophotonics,zero-mode waveguide,tryptophan autofluorescence
更新于2025-09-11 14:15:04
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UV distributed Bragg reflectors build from porous silicon multilayers
摘要： UV Distributed Bragg reflectors were fabricated by a two-step thermal oxidation process over porous silicon multilayers (PS-ML), which were prepared by room-temperature electrochemical anodization of silicon wafers. The optical behavior of the PS-ML before and after oxidation was studied by reflectance measurements. It was observed an UV shift from 430 to 300 nm in the peak of the reflectance spectrum after oxidation of the PS-ML. This was attributed to the presence of silicon oxide over the surface of the silicon filaments. Such oxide also reduced the refractive index of each porous silicon monolayer. The bandgap of the PS-ML was calculated by the Kubelka-Munk approximation, which showed an increase in the bandgap from 3.11 to 4.36 eV after the thermal oxidation process. It was suggested that the observed optical response could opens the possibility of fabrication of UV optoelectronic devices based entirely in the silicon technology.
关键词： Porous silicon,thermal oxidation,multilayers,ultraviolet (UV)
更新于2025-09-09 09:28:46