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Investigation of cut quality in fiber laser cutting of CFRP
摘要： Fiber laser cutting of CFRP sheets was investigated using a 2 kW multi-mode fiber laser, focusing on how the cut quality factors, such as kerf width, kerf depth, matrix evaporation width, matrix recession width, kerf taper angle, matrix damage zone, and cut surface morphology, change as laser power, laser scanning speed, and the number of laser passes are varied. By designing a systematic experiment on a large process window, several important parameters for kerf width, kerf depth, matrix evaporation width, and matrix recession width were identified, and using them, it was verified that the beam scanning speed is a dominant factor for minimizing thermal damages. Also, circular rings were observed in each carbon fiber at the cut surfaces, and it looked as if they were generated when each fiber was thermally fused in the radial direction. A larger number of laser passes was found to contribute to a smooth surface morphology, because of the formation of highly-fused surfaces, which prevents fiber delamination and pull-outs. Optimum process conditions were also identified by comparing various cut quality factors.
关键词： Fiber laser cutting,Optimal process conditions,Cut quality factors,Thermal damage,Carbon fiber reinforced plastic (CFRP)
更新于2025-11-28 14:24:20
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Screening of two-photon activated photodynamic therapy sensitizers using a 3D osteosarcoma model
摘要： Photodynamic therapy (PDT) involves a photosensitizing agent activated with light to induce cell death. Two-photon excited PDT (TPE-PDT) offers numerous benefits compared to traditional one-photon induced PDT, including an increased penetration depth and precision. However, the in vitro profiling and comparison of two-photon photosensitizers (PS) are still troublesome. Herein, we report the development of an in vitro screening platform of TPE-PS using a 3D osteosarcoma cell culture. The platform was tested using three different two-photon (2P) active compounds – a 2P sensitizer P2CK, a fluorescent dye Eosin Y, and a porphyrin derivative (TPP). Their 2P absorption cross-sections (σ2PA) were characterised using a fully automated z-scan setup. TPP exhibited a remarkably high σ2PA at 720 nm (8865 GM) and P2CK presented a high absorption at 850 nm (405 GM), while Eosin Y had the lowest 2P absorption at the studied wavelengths (<100 GM). The cellular uptake of PS visualized using confocal laser scanning microscopy showed that both TPP and P2CK were internalized by the cells, while Eosin Y stayed mainly in the surrounding media. The efficiency of the former two TPE-PS was quantified using the PrestoBlue metabolic assay, showing a significant reduction in cell viability after two-photon irradiation. The possibility of damage localization was demonstrated using a co-culture of adipose derived stem cells together with osteosarcoma spheroids showing no signs of damage to the surrounding healthy cells after TPE-PDT.
关键词： two-photon excited photodynamic therapy,PrestoBlue assay,photosensitizers,cellular uptake,localized damage,z-scan,3D osteosarcoma model
更新于2025-11-21 11:08:12
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Effects of ion beam etching of fused silica substrates on the laser-induced damage properties of antireflection coatings at 355?nm
摘要： Antire?ection (AR) coatings are deposited on UV grade fused silica substrates, which are cleaned in the dual ion beam sputtering device. Compared to ultrasonic and acid etching cleaning progress, ion beam etching improves the laser-induced damage threshold (LIDT) of substrates and AR coatings signi?cantly at 355 nm. Ion beam etching declines the low LIDT defects drastically and removes lots of the impurity elements (Ce, Fe, K, and Na). Roughness test shows that the AR coatings and substrates with ion beam etching are very ?at and of low roughness. Ion beam etching reduces the density of deep defect from substrates greatly. Damage morphologies show double layers delamination, which is explained via calculation of layer stress. This study will be helpful for preparation of high LIDT optical coatings.
关键词： Laser damage,AR coatings,355 nm,Substrate cleaning
更新于2025-11-14 15:19:41
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Ultraviolet to blue blocking and wavelength convertible films using carbon dots for interrupting eye damage caused by general lighting
摘要： Our eyes are regularly exposed to ultraviolet (UV) and blue light emitting diode (LED) light-based devices. However, the blue light induces macular degeneration, optic nerve crush, eye strain, and increases reactive oxygen species, which negatively influence eye-related cells (photoreceptor and retinal pigmented epithelial cells). UV light is also harmful to humans. It induces photokeratitis, cataract, and ocular surface squamous neoplasia. Here, we present carbon dot films with different carbon dot contents, prepared by a simple method. The films exhibit strong UV and blue light absorption. The transmittance of carbon dot films is >70% in the visible region (>500 nm). The UV light blocking ratio of commercial blue blocking filter and carbon dot film using UV LED chips is 94.1% and 95.9% (40 wt%), respectively. The blue light blocking ratio of commercial blue blocking filter and carbon dot film using blue LED chips is 10.2% and 82.3% (40 wt%), respectively. These results indicate that the prepared carbon dot films have a UV blocking rate similar to that of commercial blue blocking filters and a much better blue blocking rate than commercial blue blocking filters. Therefore, they can be effectively used as UV and blue blocking films in various applications.
关键词： White LED,Eye damage,UV blocking film,Carbon dot,blue blocking film
更新于2025-11-14 15:15:56
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Laser damage characteristics of indium-tin-oxide film and polyimide film
摘要： This report focuses on the damage characteristics of the indium-tin-oxide (ITO) layer and the polyimide (PI) layer, which are two constituent components of a LCD. This investigation is different from the previous study, in which the alignment layer was deposited directly on a glass substrate. The PI alignment layer is pinned on the ITO film to imitate the structure of the LCD as much as possible in our current study. The damage process of the ITO/Glass sample involves melting, vaporization near the laser-induced damage threshold (LIDT), and removal at a higher fluence. However, the damage process of the PI/ITO/Glass sample involves thermally induced plastic deformation, followed by cooling when the irradiation fluence is near the LIDT, and rupture when the irradiation fluence is higher. The LIDTs of the PI/ITO/Glass samples, as determined by the on-line CCD detection technique, are higher than those of the ITO/Glass samples. The favorable mechanical properties of the PI are primarily responsible for this result.
关键词： PI film,ITO film,near-infrared laser damage
更新于2025-10-22 19:40:53
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Fusion of Multi-Temporal Interferometric Coherence and Optical Image Data for the 2016 Kumamoto Earthquake Damage Assessment
摘要： Earthquakes are one of the most devastating types of natural disasters, and happen with little to no warning. This study combined Landsat-8 and interferometric ALOS-2 coherence data without training area techniques by classifying the remote sensing ratios of specific features for damage assessment. Waterbodies and highly vegetated areas were extracted by the modified normalized difference water index (MNDWI) and normalized difference vegetation index (NDVI), respectively, from after-earthquake images in order to improve the accuracy of damage maps. Urban areas were classified from pre-event interferometric coherence data. The affected areas from the earthquake were detected with the normalized difference (ND) between the pre- and co-event interferometric coherence. The results presented three damage types; namely, damage to buildings caused by ground motion, liquefaction, and landslides. The overall accuracy (94%) of the confusion matrix was excellent. Results for urban areas were divided into three damage levels (e.g., none–slight, slight–heavy, heavy–destructive) at a high (90%) overall accuracy level. Moreover, data on buildings damaged by liquefaction and landslides were in good agreement with field survey information. Overall, this study illustrates an effective damage assessment mapping approach that can support post-earthquake management activities for future events, especially in areas where geographical data are sparse.
关键词： damage assessment,Landsat-8,ALOS-2 interferometric coherence,urban damage area,liquefaction,landslides,Kumamoto earthquake
更新于2025-09-23 15:23:52
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Computational Study on Interfaces and Interface Defects of Amorphous Silica and Silicon
摘要： The amorphous SiO2/Si interface is arguably the most important part in semiconductor technology, strongly influencing the device reliability. Its electronic structure is affected by the defects, majorly the dangling bonds known as Pb-type defects, which have been studied for decades. These defects are usually passivated by hydrogen atoms in device processing, which eliminates the defect levels in the silicon bandgap and thus removes their electric activity. However, when the interface is exposed to ionization radiation, the passivated defects can be reactivated by the protons generated by radiation, which significantly affects the device performance and causes reliability issues. In this review, computational studies on the amorphous SiO2/Si interface and interface defects are summarized, including the modeling of the interface, the main interface defects, and their depassivation, and compared to experimental results. The hyperfine parameters are emphasized, because they are essential to identify the structures of the interface defects. The defect levels and depassivation of the defects are also emphasized, because the former directly affect the device performance and the latter directly generates the dangling bonds in the interface.
关键词： depassivation,ionizing damage,interface defects,amorphous interfaces,first-principles calculations
更新于2025-09-23 15:23:52
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Suppression of Light-Induced Oxidative Stress in the Retina by Mitochondria-Targeted Antioxidant
摘要： Light-induced oxidation of lipids and proteins provokes retinal injuries and results in progression of degenerative retinal diseases, such as, for instance, iatrogenic photic maculopathies. Having accumulated over years retinal injuries contribute to development of age-related macular degeneration (AMD). Antioxidant treatment is regarded as a promising approach to protecting the retina from light damage and AMD. Here, we examine oxidative processes induced in rabbit retina by excessive light illumination with or without premedication using mitochondria-targeted antioxidant SkQ1 (10-(6’-plastoquinonyl)decyltriphenyl-phosphonium). The retinal extracts obtained from animals euthanized within 1–7 days post exposure were analyzed for H2O2, malondialdehyde (MDA), total antioxidant activity (AOA), and activities of glutathione peroxidase (GPx) and superoxide dismutase (SOD) using colorimetric and luminescence assays. Oxidation of visual arrestin was monitored by immunoblotting. The light exposure induced lipid peroxidation and H2O2 accumulation in the retinal cells. Unexpectedly, it prominently upregulated AOA in retinal extracts although SOD and GPx activities were compromised. These alterations were accompanied by accumulation of disulfide dimers of arrestin revealing oxidative stress in the photoreceptors. Premedication of the eyes with SkQ1 accelerated normalization of H2O2 levels and redox-status of lipids and proteins, contemporarily enhancing AOA and, likely, sustaining normal activity of GPx. Thus, SkQ1 protects the retina from light-induced oxidative stress and could be employed to suppress oxidative damage of proteins and lipids contributing to AMD.
关键词： SkQ1,superoxide dismutase,glutathione peroxidase,disulfide dimerization of proteins,visual arrestin,age-related macular degeneration,mitochondria-targeted antioxidant,antioxidant activity,light-induced retinal damage,oxidative stress
更新于2025-09-23 15:23:52
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Low temperature characteristics of SiPMs after very high neutron irradiation
摘要： The design of the CMS phase II upgrade for the HL-LHC uses SiPMs for the Barrel Timing Layer (BTL) and the Behind HCAL detector (BH or CEH). In both sub-detectors the SiPMs will see a 1 MeV equivalent dose of around 1014 n/cm2. To lower the noise in the SiPMs the design is to keep the SiPMs at a low temperature of ?30 ?C. Different samples from two manufactures of SiPMs were irradiated to a total dose of resp. 2 × 1012, 5 × 1013 at the TRIGA reactor at the JSI in Slovenia. The noise in SiPMs is dominated by trap assisted tunneling which is a result of the high internal electric field in SiPMs. We therefore studied the noise behavior from +10 ?C to ?40 ?C from standard high internal field and specially designed low field SiPMs from FBK-irst and Hamamatsu. After the initial characterization before annealing the noise decrease in SiPMs was also studied using accelerated annealing.
关键词： Silicon photomultiplier,MPPC,CMS,GAPD,Radiation damage
更新于2025-09-23 15:23:52
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Image processing for three defects of topography images by SPM
摘要： Image processing plays an important role in the topography imaging by SPM. Due to the imperfect hardware and the environmental interference, the image defects can be easily found in the topography images. In order to deal with these defects, image processing technology is the most effective and convenient way, so image processing functions are integrated in most kinds of SPM software. In this study, we present image processing methods for three common defects of topography images: background, damage and fringe. According to the characteristics of the topography images and the defects, some algorithms are adopted in the proposed methods, such as B-spline, TV, Criminisi, Flourier transform and so on. The principles, processes and application scopes of the methods were described in detail, and the topography images with typical defects were selected to verify them. The processing results showed the feasibility of the methods, which offer an effective approach to acquire high-quality topography images in a fast, simple and cheap way.
关键词： Background,Damage,Topography image,Fringe,SPM,Image processing
更新于2025-09-23 15:23:52