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Comparison of acetaminophen degradation in UV-LED-based advance oxidation processes: Reaction kinetics, radicals contribution, degradation pathways and acute toxicity assessment
摘要： Ultraviolet light emitting diode (UV-LED)-based advanced oxidation processes (AOPs) including UV-LED/chloramine (UV-LED/NH2Cl), UV-LED/hydrogen peroxide (UV-LED/H2O2) and UV-LED/persulfate (UV-LED/PS), were adopted for acetaminophen (AAP) removal. Results showed that AAP could be effectively degraded by the hybrid processes compared to solely using with UV irradiation and oxidants. The AAP degradation in the three UV-LED-based AOPs were in the order of UV-LED/PS N UV-LED/H2O2 N UV-LED/NH2Cl and followed a pseudo-?rst-order kinetics. The degradation rate constant (kobs) increased with increasing oxidant dosage, whereas overdosing lowered the AAP degradation. The second-order rate constants of HO?, SO4??, and Cl? with AAP were calculated as 5.15 × 109, 7.66 × 109 and 1.08 × 1010 M?1 s?1, respectively. Under neutral conditions, the contributions of UV-LED, HO?, and Cl? to AAP degradation were 4.21%, 60.15% and 35.64% in the UV-LED/NH2Cl system, whereas the respective contributions of UV-LED, HO? and SO4?? to AAP degradation were 2.09%, 22.84% and 75.07% in UV-LED/PS system, respectively. Meanwhile, the corresponding contributions of the involved reactive species were found to be pH-dependence. The natural organic materials (NOM) inhibited the ? had different effects on AAP degradation in the ?, and NO3 AAP degradation, and the presence of Cl?, HCO3 three hybrid processes. The AAP degradation was signi?cantly inhibited in the three UV-LED-based AOPs in real water. In addition, the intermediate products were also identi?ed, and possible degradation pathways were proposed in the three UV-LED-based AOPs. The acute toxicity bioassay using bacterium Vibrio ?scheri suggested that the UV-LED/PS process was more effective than the UV-LED/H2O2 and UV-LED/NH2Cl processes in reducing the acute toxicity of the reacted AAP solution. Among the three UV-LED-based AOPs, the UV-LED/PS was found to be the most ef?cient process for AAP degradation.
关键词： Acute toxicity,Rate constants,UV-LED-based AOPs,Degradation pathways,Acetaminophen
更新于2025-09-23 15:21:01
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Angular and spatial color mixing using mixing rods with the geometry of a chaotic-dispersive billiard system
摘要： For mixing light from different colored LEDs, an optical color mixing system is required to avoid colored shadows and color fringes. Concerning the different color mixing systems, mixing rods are widespread as they provide very good spatial color mixing with high efficiency. The essential disadvantage of mixing rods, so far, is the lack of angular color mixing. The solution presented in this publication is the application of a chaotic-dispersive billiard’s geometry on the cross section of the mixing rod. To show both the spatial and the angular mixing properties of a square and a chaotic-dispersive mixing rod, simulations generated by the raytracing software ASAP are provided. All results are validated with prototype measurements.
关键词： chaotic billiards,LED color mixing,mixing rods
更新于2025-09-23 15:21:01
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High Voltage, Low Current High-Power Multichannel LEDs LLC Driver by Stacking Single-Ended Rectifiers with Balancing Capacitors
摘要： In this paper, a new LLC converter for series-connected, high-voltage LEDs is proposed. The proposed LLC converter consists of two stacked, single-ended recti?ers and one balancing capacitor, to compensate for the current deviation of two individual LED strings. The proposed LLC LED driver can use a diode with low voltage stress, even if the secondary LED is connected in series to have a high driving voltage. In addition, even if several series-connected LEDs are changed into two-stacked structures, the balancing capacitor can compensate for the current deviation of the two separated LEDs, as well as the di?erence in leakage inductance of the two stacked single-ended recti?ers. The balancing capacitor can be made equal to the voltage tolerance of the stacked, single-ended recti?er diodes. The proposed circuit can be easily extended to a series channel LED driver circuit, without increasing the voltage stress. To verify the characteristics and operation of the proposed LLC LED driver, a 260W high-power LED driver is implemented.
关键词： high-power LED light,stacked single-end recti?er,balancing capacitor,LLC LED driver
更新于2025-09-23 15:19:57
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Comparative analysis of different cooling fin types for countering LED luminaires' heat problems
摘要： A significant problem with high-power LED luminaires is heat. Aluminum heat sinks have been extensively used as a solution. The most common method for heat sinks that increases surface area uses fins. In the present study, pin- and plate-fins were compared and it was observed that, in equal surface areas, better cooling was achieved by pin-fins. Thus, the study’s concentration narrowed to pin-fins and the results of different pin-fins were compared. Simulations of a sample group were conducted by using different numbers of fins, and the number of fins giving the lowest Tmax value (the highest junction point temperature) was accepted to be optimum for each group; then the optimum values were compared among the different groups. Keeping the base width of fins constant, optimum values were obtained for the same number of fins when the fin height was changed. However, keeping fin height constant, surface areas of optimum values and measured Tmax values were very close to one another other, even if the base width of fins was changed. The results have practical significance in designing high-power LED luminaires.
关键词： LED cooling,fin height,junction point temperature,base width,High-power LED luminaire,plate-fin heat sink,pin-fin heat sink
更新于2025-09-23 15:19:57
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Coagulation performance of cationic polyelectrolyte/TiO <sub/>2</sub> nanocomposites prepared under LED irradiation
摘要： A series of acrylic-based cationic polyelectrolyte nanocomposites including water-soluble monomers acrylamide (AAm) and 2-acryloyloxyethyltrimethylammonium chloride (DAC) with different mole percent of DAC (30, 40, and 45%) in feed were produced using TiO2 nanoparticles (0.018, 0.037, and 0.11 wt%) as photoinitiator in the aqueous solution of monomers and named as p(ADT)1–9. The LED light at 365 nm was used for photocatalysis activation of TiO2 nanoparticles. Structure and morphology of the synthetic polyelectrolyte were characterized by FT-IR, NMR, TGA, FESEM-EDX, and TEM. The other properties of synthetic polyelectrolyte such as molecular weight, viscosity, charge density, AAm/DAC molar ratio in copolymers, reactivity ratio values for the AAm and DAC monomers, and polymerization degree were measured. Furthermore, coagulation performance of these polyelectrolytes was investigated in soil suspension (1,000 ml, turbidity = 1,715 NTU). The prepared nanocomposites enhanced the coagulation of soil suspension up to 99.5% in low dosages. The best turbidity removal efficiencies (TRE) between 99.5–99.77% were achieved by p(ADT)3 conatining 30% DAC and 0.11 wt% TiO2. Decreasing the temperature from room temperature to 0°C led to an increase in TRE from 98 to 99.8%. Also, increasing the pH from 4 to 12 led to a decrease in TRE from 99.86 to 94%.
关键词： photopolymerization,cationic polyelectrolyte,coagulation performance,LED irradiation,TiO2 nanocomposites
更新于2025-09-23 15:19:57
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Photobiomodulation with 630-nm LED radiation inhibits the proliferation of human synoviocyte MH7A cells possibly via TRPV4/PI3K/AKT/mTOR signaling pathway
摘要： Phototherapy has been used to treat postoperative pain and inflammatory response in rheumatoid arthritis. Confidence in this approach, however, is impaired by lack of understanding of the light-triggered cellular and molecular mechanisms. The purpose of this study was to characterize the response of human synoviocyte MH7A cells to visible LED red light in an attempt to elucidate the associated action mechanism. Human synoviocyte MH7A cells were treated with 630-nm LED light after stimulation of tumor necrosis factor-α (TNF-α). The effects of light radiation on cell proliferation and migration were detected by MTT assay and scratch test. The expressions of inflammatory cytokines were measured using RT-qPCR. This was followed by detection of the levels of extracellular proteins IL-6 and IL-8 after differential radiation. Furthermore, the expression levels and activation of proteins on PI3K/AKT/mTOR signaling pathway were examined with Western blot. In terms of the proliferation and migration, repeated radiation with LED red light (630 nm, 26 and 39 J/cm2) exerted an inhibitory effect on synoviocyte MH7A cells. Expression of inflammatory factors (IL-6, IL-1β, IL-8, and MMP-3) was reduced; meanwhile, the expression of anti-inflammatory factor IL-10 was promoted. At the protein level, treatment with 39 J/cm2 of LED red light could decrease the level of extracellular protein (IL-6 and IL-8) and affect the expression and phosphorylation of proteins on TRPV4/PI3K/AKT/mTOR signaling pathway induced by TNF-α. These results demonstrated that LED red light (630 nm) inhibits proliferation and migration of MH7A cells. The growth-inhibiting effects of LED red light on human synoviocyte MH7A cells appear to be associated with regulation of the TRPV4/PI3K/AKT/mTOR signaling pathway.
关键词： PI3K/AKT/mTOR pathway,TRPV4 channel,Proliferation,630-nm LED,Synoviocyte
更新于2025-09-23 15:19:57
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Investigating the Photochemistry of Spiropyran Metal Complexes with Online LED-NMR
摘要： As one of the best studied photoswitches, spiropyrans (SPs) have attracted significant interest in the scientific community. Among the many stimuli to alter the isomerization into the merocyanine (MC) isomer, such as temperature, pH, solvent polarity, redox potential, or mechanical force, the ability of the MC form to act as a ligand site for metal complexation has recently raised new attention. We herein synthesize hitherto undescribed coordination compounds of 8-methoxy-1′,3′,3′-trimethyl-6-nitrospiro-[chromene-2,2′-indoline] with s-block ([Ca(MC)4](ClO4)2), d-block ([Zn(MC)2(MeCN)2](ClO4)2, [Ni(MC)2(MeCN)2](ClO4)2), as well as f-block ([La(NO3)3(MC)2]) metals. All complexes are structurally described by X-ray crystallography and systematically investigated in solution via Job’s method of continuous variations (Job plots), as well as online NMR spectroscopic kinetic experiments with in situ irradiation of the analyte solution inside the NMR spectrometer (LED-NMR). We can unambiguously identify the photoresponsive nature of the complexes in solution, which is a crucial step toward the application of these promising molecules in material science.
关键词： photochemistry,LED-NMR,metal complexes,X-ray crystallography,spiropyrans
更新于2025-09-23 15:19:57
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Encrypted Chaos in Quantum Dot Light Emitting Diode
摘要： A communication scheme based on the synchronization of two chaotic quantum dot light emitting diodes (QD-LEDs) is theoretically examined. The Chaos in the QD-LED is generated by means of an optical feedback. Synchronization of the chaos is achieved by varying coupling strength between the transmitter and the receiver as unidirectional coupling. The proposed communication schemes is test a by successfully transmitting messages.
关键词： chaos synchronization,optical feedback,QD-LED,communication
更新于2025-09-23 15:19:57
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Protein Content Sensor based on Plastic Optical Fiber
摘要： Plastic optical fiber (POF) content protein sensor has been developed. This sensor is made with a gamma and spiral configuration, with a cladding peel length of 5 cm. POF sensor is dipped into the container containing Bovine Serum Albumin (BSA) solution with different concentrations of 0.1-1 mg/ml. Both ends of the sensor are connected by Light Emiting Diode (LED) and Phototransistor. The LED light will propagate through the POF and it is received by the phototransistor. Light that propagates will be interfenced due to increasing of protein concentration around the sensor, so that the output voltage will be affected. The output voltage will be forwarded to Arduino Uno and read by the computer. The best results were obtained in a spiral configuration with 3 bending with a sensitivity of 0.007 Vml/mg and a resolution of 0.142 mg/ml. This method has advantages that are easy fabrication, simple measurement process, and low cost.
关键词： protein sensor,Plastic optical fiber,Phototransistor,Arduino Uno,Bovine Serum Albumin,LED
更新于2025-09-23 15:19:57
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[IEEE IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Lisbon, Portugal (2019.10.14-2019.10.17)] IECON 2019 - 45th Annual Conference of the IEEE Industrial Electronics Society - Sensorless Current Control of Large-Scale LED Lighting Systems based on SIMO LED Drivers
摘要： Most of the state-of-the-art LED drivers employed in lighting applications adopt current control strategies that rely on current sensing resistors. In multi-string LED lighting systems, commonly based on the single inductor multiple output (SIMO) topology, a current sensing resistor is typically inserted in each string, allowing to precisely control the current flowing through each string. This current control approach presents critical drawbacks: 1) the overall energy conversion efficiency is seriously affected by the fairly high number of current sensing resistors; 2) the system complexity is enhanced, as each LED string requires a current control loop; 3) the lifetime of both LEDs and drivers suffers an important depreciation due to the additional power losses incurred by the current sensing resistors. To overcome such drawbacks, this paper proposes a sensorless current control strategy suitable for LED drivers operated at continuous conduction mode (CCM), feeding multi-string LED lighting systems, which obviates the requirement of individual string current control. The proposed control strategy is implemented and validated on a fault-tolerant SIMO LED driver.
关键词： DC-DC converters,Sensorless control,LED lighting,Reliability,Efficiency
更新于2025-09-23 15:19:57