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Evaluation of laser-induced carbons with concentric graphitic layers for highly durable and adaptable at low humidity
摘要： Laser-induced carbons, so-called onion-like carbon (OLC), were investigated for enhanced oxygen reduction reaction activity, excellent durability of catalysts on carbon supports, and adaptability at a low relative humidity (44% RH). OLC nanoparticles were obtained by laser irradiation of ethylene with different reaction positions. The residence time and energy distribution at a reaction zone lead to the formation of nano-carbons with graphitic shells. As a robust support compared to commercial carbon black (XC), the OLC nanoparticle consisting of concentric graphitic layers is fabricated and its structure with sp hybridizations helps strong interactions between Pt atoms and π-bond of OLC nanoparticles, preventing the surface migration of Pt atoms, resulting in enhanced durability in long-term operations. It leads that the downshift of Pt d-band center at Pt nanocatalysts on OLC shells structures reduces the adsorption strength of surface oxygen species, enhancing ORR activity. Compared to the Pt/XC, the performance of Pt/OLC nanocatalyst shows 1.27 times more active in low humidity conditions, and 1.36 times more active and durable after long-term operating in extreme conditions occurring carbon corrosion levels. These results exhibit that the Pt/OLC catalyst is expected to generate an incredible level of synergy for enhanced activity and durability.
关键词： Durability,Graphitic layers,Laser irradiation,Onion-like carbons
更新于2025-09-12 10:27:22
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Transcription-coupled nucleotide excision repair is coordinated by ubiquitin and SUMO in response to ultraviolet irradiation
摘要： Cockayne Syndrome (CS) is a severe neurodegenerative and premature aging autosomal-recessive disease, caused by inherited defects in the CSA and CSB genes, leading to defects in transcription-coupled nucleotide excision repair (TC-NER) and consequently hypersensitivity to ultraviolet (UV) irradiation. TC-NER is initiated by lesion-stalled RNA polymerase II, which stabilizes the interaction with the SNF2/SWI2 ATPase CSB to facilitate recruitment of the CSA E3 Cullin ubiquitin ligase complex. However, the precise biochemical connections between CSA and CSB are unknown. The small ubiquitin-like modifier SUMO is important in the DNA damage response. We found that CSB, among an extensive set of other target proteins, is the most dynamically SUMOylated substrate in response to UV irradiation. Inhibiting SUMOylation reduced the accumulation of CSB at local sites of UV irradiation and reduced recovery of RNA synthesis. Interestingly, CSA is required for the efficient clearance of SUMOylated CSB. However, subsequent proteomic analysis of CSA-dependent ubiquitinated substrates revealed that CSA does not ubiquitinate CSB in a UV-dependent manner. Surprisingly, we found that CSA is required for the ubiquitination of the largest subunit of RNA polymerase II, RPB1. Combined, our results indicate that the CSA, CSB, RNA polymerase II triad is coordinated by ubiquitin and SUMO in response to UV irradiation. Furthermore, our work provides a resource of SUMO targets regulated in response to UV or ionizing radiation.
关键词： SUMOylation,DNA damage response,transcription-coupled nucleotide excision repair,Cockayne Syndrome,UV irradiation,ubiquitination
更新于2025-09-12 10:27:22
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Proton Irradiation on Cesium‐Fluoride‐Free and Cesium‐Fluoride‐Treated Cu(In,Ga)Se <sub/>2</sub> Solar Cells and Annealing Effects under Illumination
摘要： Several studies have been performed on proton irradiation onto alkali-metal untreated Cu(In,Ga)Se2 (CIGS) solar cells. However, there are almost no studies describing similar effects on alkali-treated CIGS solar cells. With this motivation, this work investigates proton irradiation and annealing effects under illumination on cesium-?uoride-free (CsF-free) and CsF-treated CIGS solar cells. Both CsF-free and CsF-treated CIGS solar cells degrade under proton irradiation. External quantum ef?ciency measurements show degradation in long wavelengths after the treatment. The experimental data are ?tted with a simulation, which show that proton-irradiated degradation is more severe at high ?uence. Capacitance–voltage measurements show a broadening of the depletion region after proton irradiation, which is due to the decreased net carrier concentration. It is proposed that proton irradiation at low ?uence generates shallow-type defects, whereas high-?uence protons generate deep defects. However, it is observed that room-temperature storage of the proton-irradiated solar cells causes partial recovery. Thermal annealing under illumination treatments is found to be bene?cial to the drastic recovery of the performance of solar cells irradiated at low ?uence. High-?uence proton-irradiated solar cells undergo minor recovery.
关键词： Cu(In,Ga)Se2 solar cells,cesium-?uoride,heat-light soaking,proton irradiation,annealing
更新于2025-09-11 14:15:04
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Feasibility of transgingival laser irradiation for antimicrobial photodynamic therapy
摘要： Aim: Diode lasers are commonly used for antimicrobial photodynamic therapy (aPDT). This study aimed to assess the feasibility of transgingival laser irradiation during aPDT and evaluate whether the photosensitizer can be activated. Materials and Methods: Four diode laser settings were assessed for transgingival irradiation: 120 mW, 80 mW, 60 mW, and 40 mW. Fifteen soft-tissue pieces from a pig’s lower jaw were prepared. The specimens’ thickness was measured and transgingival laser irradiation was performed. A digital power meter measured laser power on the other side of the tissue. The power outcome after staining of the nonbuccal aspect of the tissue with photosensitizer dye was assessed similarly. Results: Transgingival laser irradiation (average soft-tissue thickness: 0.84 ± 0.06 mm) resulted in di?erent power transmission depending on the power settings and photosensitizer. The lowest values were observed with the 40 mW setting and photosensitizer (median 3.3 mW, max. 5.0 mW, min. 2.3 mW, interquartile range 1.2), and the highest at 120 mW without photosensitizer (median 41.3 mW, max. 42.7 mW, min. 38.0 mW; interquartile range 1.5). Conclusions: This study indicates that transgingival irradiation may be suitable for aPDT, since power transmission through the gingival tissue was observed in all specimens. However, the decrease in laser power caused by both the soft tissue and the photosensitizer has to be taken into account.
关键词： Transgingival irradiation,Low-level laser therapy,Periodontitis,Diode laser,Antimicrobial photodynamic therapy
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE Workshop on Power Electronics and Power Quality Applications (PEPQA) - Manizales, Colombia (2019.5.30-2019.5.31)] 2019 IEEE Workshop on Power Electronics and Power Quality Applications (PEPQA) - Integration of Photovoltaic System in Low Voltage Electrical Network of the Electrical Engineering Building
摘要： The quantification of the impacts of photovoltaic system (PV) integration in the low voltage (LV) power grid is necessary for the historical evaluation of the electrical network with and without PV penetration. This paper presents the study case of the LV electrical network of a university building (Colombia), which has a 9.1 kW PV system. Specifically, the electrical variables monitored were voltages (V), frequency (f), active power (W), voltage distortion (THDv), and harmonics at the Point of Common Coupling (PCC), to determine impairments according to Std. IEEE 1547-2018. PV systems could change the RMS value of voltage at the PCC, therefore, this variable was analysed. Likewise, the frequency was analysed to corroborate the no affectation of the interconnection of the PV system to the electrical network; it is due to the absence of rotational inertia. The solar irradiation information was measured by a pyranometer and the electrical variables by an smart meter, recording the information every 10 minutes for 32 days. The above is an initial step for a comprehensive evaluation of electrical variables with PV generation and future integration of parameters for the resilience evaluation of the electric network.
关键词： harmonics,frequency,photovoltaic systems,resilience,voltage,irradiation solar,Distributed generation
更新于2025-09-11 14:15:04
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Radiation Hardness of Perovskite Solar Cells Based on Aluminum‐Doped Zinc Oxide Electrode Under Proton Irradiation
摘要： Perovskite solar cells (PSCs) have gained increasing interest for space applications. However, before they can be deployed into space, their resistance to ionizing radiations, such as high-energy protons, must be demonstrated. Herein, the effect of 150 keV protons on the performance of PSCs based on aluminum-doped zinc oxide (AZO) transparent conducting oxide (TCO) is investigated. A record power conversion efficiency of 15% and 13.6% is obtained for cells based on AZO under AM1.5G and AM0 illumination, respectively. It is demonstrated that PSCs can withstand proton irradiation up to 1013 protons cm?2 without significant loss in efficiency. From 1014 protons cm?2, a decrease in short-circuit current of PSCs is observed, which is consistent with interfacial degradation due to deterioration of the Spiro-OMeTAD holes transport layer during proton irradiation. The structural and optical properties of perovskite remain intact up to high fluence levels. Although shallow trap states are induced by proton irradiation in perovskite bulk at low fluence levels, charges are released efficiently and are not detrimental to the cell’s performance. This work highlights the potential of PSCs based on AZO TCO to be used for space applications and gives a deeper understanding of interfacial degradation due to proton irradiation.
关键词： space,aluminum-doped zinc oxide,perovskite solar cells,proton irradiation
更新于2025-09-11 14:15:04
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Reversibly Photoswitchable Dual-Color Fluorescence and Controlled Release Properties of Polymeric Nanoparticles
摘要： Here, we report a novel polymeric nanoparticle prepared by the self-assembly of amphiphilic copolymers containing a ?uorescent naphthalimide (NAPH) and a photochromic spiropyran (SP), which possesses reversibly photoswitchable dual-color ?uorescence and controlled release properties. The amphiphilic copolymers were synthesized by incorporating NAPH and SP into methyl ether poly(ethylene glycol)-poly(β-amino esters) (MPEG-PAE) via quaternization. The nanoparticles would change between yellow and purple reversibly upon UV and visible light irradiation because of the photoisomerization between SP and merocyanine (MC). The corresponding ?uorescence would be switched between green and orange-red reversibly upon blue light excitation through the ?uorescence resonance energy transfer from the excited NAPH to the photoisomerized MC. Meanwhile, the prepared spherical nanoparticles could be swollen under UV irradiation as the hydrophobic SP isomerized to hydrophilic MC; the nanoparticles could also be swollen under acidic conditions because of the protonation of the amino groups of PAE. Upon UV light irradiation and acidic stimulation, the cargoes, hydrophobic Coumarin 102, encapsulated in the nanoparticles would be released. The prepared nanoparticles, which exhibit not only excellent reversible dual-color ?uorescence properties but also prominent controlled release performance, will open up new possibilities for the combined application of ?uorescence imaging and controlled release.
关键词： naphthalimide,Coumarin 102,spiropyran,polymeric nanoparticles,photoswitchable,amphiphilic copolymers,acidic conditions,quaternization,self-assembly,FRET,UV/vis light irradiation,dual-color ?uorescence,MPEG-PAE,controlled release
更新于2025-09-11 14:15:04
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Plasmonic oxidation of glycerol using AuPd/TiO2 catalysts
摘要： AuPd nanoparticles supported on P25 TiO2 (AuPd/TiO2) were prepared by a facile sol-immobilisation method and investigated for surface plasmon-assisted glycerol oxidation under base-free conditions. The AuPd/TiO2 samples were characterized by UV-vis spectroscopy and transmission electron microscopy. The sol-immobilisation method readily permitted the Au:Pd molar ratio to be changed over a wide range whilst keeping the mean particle size of the AuPd nanoparticles at 3nm. Visible light irradiation during the reaction has a beneficial effect on the conversion of glycerol with the most marked effect being observed with gold-rich catalysts and the increase of conversion on light irradiation increases linearly with the gold content of the nanoparticles. The reaction selectivity is also affected by the plasmon-assisted oxidation and glycolic acid, not observed during the dark reactions, was observed for all illuminated reactions due to the enhanced activity of these catalysts.
关键词： visible light irradiation,AuPd nanoparticles,glycerol oxidation,plasmonic photocatalysis,sol-immobilisation
更新于2025-09-11 14:15:04
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Radiation Tolerant Nanowire Array Solar Cells
摘要： Space power systems require photovoltaics that are lightweight, efficient, reliable, and capable of operating for years or decades in space environment. Current solar panels use planar multijunction, III-V based solar cells with very high efficiency, but their specific power (power to weight ratio) is limited by the added mass of radiation shielding (e.g. coverglass) required to protect the cells from the high-energy particle radiation that occurs in space. Here we demonstrate that III-V nanowire-array solar cells have dramatically superior radiation performance relative to planar solar cell designs and show this for multiple cell geometries and materials, including GaAs and InP. Nanowire cells exhibit damage thresholds ranging from ~10-40 times higher than planar control solar cells when subjected to irradiation by 100-350 keV protons and 1 MeV electrons. Using Monte Carlo simulations, we show that this improvement is due in part to a reduction in the displacement density within the wires arising from their nanoscale dimensions. Radiation tolerance, combined with the efficient optical absorption and the improving performance of nanowire photovoltaics, indicates that nanowire arrays could provide a pathway to realize high-specific-power, substrate-free, III-V space solar cells with substantially reduced shielding requirements. More broadly, the exceptional reduction in radiation damage suggests that nanowire architectures may be useful in improving the radiation tolerance of other electronic and optoelectronic devices.
关键词： space environment,irradiation-induced defects,radiation hard,space solar cells,Monte Carlo simulations,nanowire solar cells,high specific power
更新于2025-09-11 14:15:04
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Enhanced NO2 gas-sensing properties of Au-Ag bimetal decorated MWCNTs/WO3 composite sensor under UV-LED irradiation
摘要： Novel NO2 gas sensors that were made of Ag, Au and Au-Ag bimetal particles modified composite of multi-walled carbon nanotubes/tungsten oxide (Ag/MWCNTs/WO3, Au/MWCNTs/WO3 and Au-Ag/MWCNTs/WO3) were fabricated for sensing ppb-level NO2 gas under ultraviolet light emitting diode (UV-LED) irradiation. The effects of Ag, Au and Au-Ag bimetal decoration and under UV-LED irradiation on the response of the Ag/MWCNTs/WO3, Au/MWCNTs/WO3 and Au-Ag/MWCNTs/WO3 sensors for sensing NO2 gas were studied. The gas-sensing properties in the detection of a low concentration of NO2 gas of the Au-Ag/MWCNTs/WO3 composite were superior to bare MWCNTs/WO3, Au/MWCNTs/WO3 and Ag/MWCNTs/WO3 under UV-LED irradiation. The Au-Ag/MWCNTs/WO3 composite sensor showed responses of 28–262 % at NO2 concentrations ranging from 100 to 500 ppb under UV-LED irradiation. These responses were 2–5 times higher than that of the bare MWCNTs/WO3 composite sensor at the same NO2 concentration range. The substantial improvement in the response of the bare MWCNTs/WO3 composite to NO2 gas by its decoration with Au-Ag bimetal particles may be attributed to the enhanced catalytically active sites and photocatalytic activity. A reasonable mechanism for enhancing sensitivity was proposed.
关键词： UV irradiation,NO2 gas sensor,Photocatalytic activity,Au-Ag bimetal
更新于2025-09-11 14:15:04