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Influence of multiple laser peening on vibration fatigue properties of TC6 titanium alloy
摘要： In this study, typical TC6 titanium alloy was taken to investigate the effects of multiple laser peening (LP) on the vibration fatigue properties and microstructural evolution. The vibration fatigue experiments were conducted, while the vibration fatigue life of the specimens before and after LP was compared and the fracture morphologies were observed by scanning electron microscopy (SEM). In addition, the measurements of residual stress and microhardness were carried out. The microstructures produced by different treatments were also characterized by transmission electron microscopy (TEM) and electron backscattered diffraction (EBSD). The experimental results indicated that multiple LP could indeed enhance the vibration fatigue properties of TC6 titanium alloy. Comparing with the investigated specimen without LP, the vibration fatigue life of the specimen subjected to 5 times LP increased by 105.2%. Meanwhile, after 5 times LP, the surface residual stress transformed from tensile stress (+26 MPa) to compressive stress (?485 MPa), and the surface microhardness was 428 HV, which increased by 32.9% compared with the untreated sample. Additionally, high-density of dislocation and deformation twin were also generated after multiple LP. The improvement of vibration fatigue properties was attributed to the rewarding compressive residual stress and the beneficial microstructural evolution induced by multiple LP.
关键词： TC6 titanium alloy,Laser peening,Vibration fatigue properties,Microstructure evolution,Residual stress
更新于2025-11-14 17:04:02
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Addressing the Reliability and Electron Transport Kinetics in Halide Perovskite Film via Pulsed Laser Engineering
摘要： The long-term performance and stability of perovskites are adversely affected by their porous microstructure, tensile residual stress, and electron transport kinetics. Here, a high-speed pulsed laser processing technique is implemented to produce beneficial structural changes in organic–inorganic halide perovskites, including pore-free, crystalline structure, reduced defects, and tensile residual stress. Moreover, halide perovskite films can be converted from p-type to n-type semiconductor, which originates from crystal structure changes, giving rise to carrier dynamic changes. Comparing with traditional thermal annealing, residual tensile stress of perovskite thin film decreases by 40% after pulse laser processing, which significantly increases its stability. Pulse-laser-induced thermomechanical shock momentum can create pore-free perovskite thin films, contributing to much better reliability. Under humidity of 80% at room temperature for 500 h, the decomposition rate is reduced by more than two times, comparing thin films after pulsed laser processing with conventional thermal annealing. The thermal decomposition temperature of pulse-laser-processed perovskite thin film raises by 20 to about 220 °C. Pulse laser processing technique provides a scalable technique to tailor the structures in perovskite films with both temperature and loading control, further facilitates the design of perovskite-based devices for service under harsh conditions, and also contributes to high-performance optoelectronic applications.
关键词： semiconductors,perovskites,stability,microstructures,residual stress
更新于2025-11-14 15:24:45
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Effect of Macro-scale Mechanical Stress of Silicon Wafer on Room Temperature Photoluminescence Signals
摘要： Mechanical stress was applied to single side polished and double side polished Si wafers in polypropylene wafer containers for different localized stress levels and durations. Room temperature photoluminescence (RTPL) spectra from Si wafers were measured before and after applying localized mechanical stress. Significant changes (up to 26% increase) in RTPL intensity were measured from areas under different stress levels even 1 year after the fixtures for mechanical stress generation were removed. Significant effects of localized mechanical stress on RTPL intensity variations were measured up to 49 days after the fixture removal. Nearly fully relaxed RTPL signatures for localized mechanical stress were measured 450 days after the fixture removal. RTPL intensity is found to be very sensitive to the externally applied macro-scale mechanical stress of Si wafers and residual (or memorized) internal stress even after removal of fixtures for external mechanical stress generation.
关键词： Silicon,room temperature photoluminescence,stress relaxation,mechanical stress
更新于2025-09-23 15:23:52
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Study on the Statistical Errors in X-Ray Stress Measurement with Two-Dimensional Detector
摘要： The sin2 ψ method [1] is conventionally used well as how to measure non-destructively the residual strain and stress states of polycrystalline materials by X-ray diffraction. In the conventional method, there are D?lle-Hauk method [2] and Winholz-Cohen least squares analysis [3] as the determinations of the strain and stress states for limiting the influence of measurement errors. Many researches are made about the statistical error in those methods. In recent years, use of the X-ray stress measurements with two-dimensional detector from the conventional method is spreading. One of the measurements is called the cos α method. The measurement errors have attracted a great deal of attention for users as the spreads. Therefore, the basic equations and determinations of the strain and stress states are examined. The confidence intervals of measured stress by the cos α method. The research and development is performed for the the cos α method which took the influence of measurement errors into consideration.
关键词： Cos α method,Non-destructive inspection,Statistical errors,Two-dimensional detector,X-ray stress measurement,internal stress
更新于2025-09-23 15:23:52
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Imaging Spectrometry and Fluorometry in Support of Flex: What Can We Learn from Multi-Scale Experiments?
摘要： In advance of the FLEX mission, experimental studies are needed to better understand the factors driving Solar-Induced Fluorescence (SIF) emission from vegetation across different temporal and spatial scales. Here, we present findings from boreal (evergreen and deciduous) forest trees and Midwestern (annual) crops, illustrating effects of seasonal downregulation and drought on the fluorescence signals. Further work is needed to develop defensible, quantitative fluorescence measurements, and to partition the drivers of the fluorescence signals into effects of structure and physiology.
关键词： chlorophyll fluorescence (SIF, Fs),stress,photosynthesis,drought,temperature,chlorophyll/carotenoid pigments
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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A Low-Cost Flash Photographic System for Visualization of Droplets in Drop-on-Demand Inkjet
摘要： Hepatocellular carcinoma (HCC) is one of the most common and deadly human cancers. The 5-year survival rate is very low. Unfortunately, there are few efficacious therapeutic options. Until recently, Sorafenib has been the only available systemic drug for advanced HCC. However, it has very limited survival benefits, and new therapies are urgently needed. In this study, we investigated the anti-HCC activity of carfilzomib, a second-generation, irreversible proteasome inhibitor, as a single agent and in combination with sorafenib. In vitro, we found that carfilzomib has moderate anticancer activity toward liver cancer cells, but strongly enhances the ability of sorafenib to suppress HCC cell growth, proliferation, migration, invasion, and survival. Remarkably, the drug combination exhibits even more potent antitumor activity when tested in animal tumor models. Mechanistically, the combined treatment activates caspase-dependent and endoplasmic reticulum stress/CHOP-mediated apoptotic pathways, and suppresses epithelial–mesenchymal transition. In conclusion, our results demonstrate that the combination of carfilzomib and sorafenib has synergistic antitumor activities against HCC, providing a potential therapeutic strategy to improve the mortality and morbidity of HCC patients.
关键词： Hepatocellular Carcinoma,Proteasome Inhibitor,ER Stress,Apoptosis,Sorafenib,EMT,Carfilzomib,Synergistic Inhibition
更新于2025-09-23 15:23:52
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Nano-BaTiO3 phase transition behavior in coated BaTiO3-based dielectric ceramics
摘要： In this work, the phase structure of BaTiO3 nanopowders produced by the alkoxide-hydroxide and the hydrothermal method, respectively, was systemically investigated. BaTiO3 nanopowders with cubic phase produced by the alkoxide-hydroxide method could transform to tetragonal phase when heated to about 1100oC. Cubic to tetragonal phase transformation behavior of BaTiO3 nanopowders coated with 0.3BZT-0.7BT or 0.03Nb2O5-0.01Co2O3 was studied. The internal stress within core-shell structure was proposed to explain the BaTiO3 phase transformation behaviors. The mismatch of thermal expansion coefficient between core and shell plays a crucial role in cubic to tetragonal phase transformation of BaTiO3. By tuning the composition of shell and the ratio of the shell to the core, the cubic BaTiO3 core can transform to tetragonal phase successfully after sintering at 1100oC in BaTiO3 based ceramics with core-shell structure and it is mainly resulted by the reduced internal stress between the shell and core.
关键词： Phase transitions,BaTiO3 nanopowders,Internal stress.,Core-shell structure
更新于2025-09-23 15:23:52
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Isorhamnetin prevents H2O2?induced oxidative stress in human retinal pigment epithelial cells
摘要： Isorhamnetin, a 3-O-methylated metabolite of quercetin, exhibits antioxidant effects. However, to the best of our knowledge, no study to date has focused on the effects of isorhamnetin on retinal pigment epithelium (RPE) cells, and its underlying molecular mechanisms. Therefore, the present study aimed to examine the potential protective effect of isorhamnetin against oxidative stress in human RPE cells. The results demonstrated that pretreatment of RPE cells with isorhamnetin significantly protected cell viability against oxidative stress. In addition, isorhamnetin pretreatment inhibited hydrogen peroxide (H2O2)-induced reactive oxygen species (ROS) production and caspase-3 activation in RPE cells. Furthermore, isorhamnetin pretreatment significantly increased the phosphorylation of phosphoinositide 3-kinase (PI3K) and AKT serine/threonine kinase 1 (Akt) in RPE cells exposed to H2O2, compared with cells treated with H2O2 alone. Taken together, the present results demonstrated that isorhamnetin protected human RPE cells from oxidative stress-induced cell death, and this effect was associated with activation of the PI3K/Akt signaling pathway. Thus, isorhamnetin may be considered as a potential antioxidant useful for the prevention of age-related macular degeneration.
关键词： age-related macular degeneration,oxidative stress,isorhamnetin,retinal pigment epithelium cells
更新于2025-09-23 15:23:52
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Carteolol hydrochloride reduces visible light-induced retinal damage in?vivo and BSO/glutamate-induced oxidative stress in?vitro
摘要： The purpose of this study was to determine whether carteolol eye drops, a b-adrenoceptor antagonist used as an intraocular hypotensive agent, has protective effects against the light-induced oxidative stress in retina. Dark-adapted pigmented rats were pre-treated with topical carteolol ophthalmic solution or saline and then exposed to visible light. The effects on electroretinogram (ERG), morphology, oxidative stress, and expression of mRNAs in the retinas were determined. The L-buthionine-(S,R)-sulfoximine (BSO)/glutamate-induced oxidative stress in 661 W cells, a murine photoreceptor cell line, was evaluated by cell death assays, production of reactive oxygen species (ROS), and activation of caspase. In vivo studies showed that exposure to light caused a decrease in the amplitudes of ERGs and the outer nuclear layer (ONL) thickness and an increase of the 8-hydroxy-20-deoxyguanosine (8-OHdG)-positive cells in the ONL. These changes were significantly reduced by pre-treatment with carteolol. Carteolol also significantly up-regulated the mRNA levels of thioredoxin 1 and glutathione peroxidase 1 compared to saline-treated group. Moreover, carteolol and timolol, another b-adrenoceptor antagonist, significantly inhibited BSO/glutamate-induced cell death and reduced caspase-3/7 activity and ROS production in vitro. Therefore, carteolol could protect retina from light-induced damage with multiple effects such as enhancing the antioxidative potential and decreasing the intracellular ROS production.
关键词： Antioxidative potential,Oxidative stress,Carteolol hydrochloride,Light-induced retinal damage,Reactive oxygen species
更新于2025-09-23 15:23:52