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Inactivation of Salmonella spp. in Wheat Flour by 395 nm Pulsed Light Emitting Diode (LED) Treatment and the Related Functional and Structural Changes of Gluten
摘要： Salmonella spp. is one of the top foodborne pathogens associated with low-moisture foods and they exhibit significant resistance to conventional thermal treatments. UV light pulses emitted from light emitting diode (LED) has shown antimicrobial potential in high-moisture foods and water. However, limited information is available about the antimicrobial potential of UV light with different wavelengths, including 395 nm in low-moisture foods. The objectives of this study were to investigate the antimicrobial potential of 395 nm pulsed LED light in wheat flour and the resulting quality changes. This study demonstrated a maximum 2.91 log reduction of Salmonella cocktail in wheat flour treated with 395 nm pulsed LED for 60 min in a semi-closed system. Oxidation occurred in wheat flour after 30 and 60 min exposure to the 395 nm LED, which subsequently led to bleaching, and polymerization of gluten components through disulphide linkage. The water holding capacity of gluten was reduced by oxidation, and the contents of secondary structures were altered significantly after pulsed LED treatment, but the rheological properties were not deteriorated. The disulfide bond formation naturally happens during dough formation and the oxidation triggered by pulsed LED treatment may play a role on accelerating this process. The 395 nm pulsed LED treatment could be a promising decontamination technology for wheat flour with an additional benefit of bleaching of the flour without chemicals.
关键词： Salmonella,oxidation,wheat flour,UV-A,light emitting diode (LED),Low-moisture foods
更新于2025-09-19 17:13:59
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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) - Realization and Numerical Simulation of a High Power and High Efficiency Holmium Doped Fiber Laser at 2.1 ??m
摘要： We present a novel design and fabrication process using the hydrophilic con?nement effect and a 3-D printer for producing convex and concave microlenses on top of light-emitting diodes. We use energy conservation and a lawnmower algorithm to design a freeform lens, and transform it into heterogeneous microlenses. The diameters of the microlenses on top of the light-emitting diode are 500 and 200 μm for the concave and convex shapes, respectively. Heterogeneous microlenses are printed on a glass substrate using the hydrophilic con?nement effect of SU-8 photoresist and an inkjet printer. Then, the array is copied with a mold made by a 3-D printer for the replication process. In the replication process, the mold is ?lled with polydimethylsiloxane to reproduce heterogeneous microlenses. Experimental results show that this heterogeneous microlens array improves the light distribution uniformity of a light-emitting diode from 17% to 63%.
关键词： light-emitting diode (LED),microlenses,Freeform lens,micro-structure on LED
更新于2025-09-19 17:13:59
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Mass Transfer of Microscale Light-Emitting Diodes to Unusual Substrates by Spontaneously Formed Vertical Tethers During Chemical Lift-Off
摘要： A much simpli?ed method for transferring Gallium nitride (GaN) light emitting didoes (LEDs) to an unusual substrate, such as glass, Si, polyethylene terephthalate, or polyurethane, was demonstrated with spontaneously formed vertical tethers during chemical lift-o? (CLO), without requiring a sacri?cial layer or extra process steps. The LED arrays resided on a stamp that was coated with an adhesive layer. After the layer with the LEDs was transferred to the new substrates, the stamp was removed by acetone to complete the preparation. Over 3 × 3 cm2 LED arrays transferred to various substrates without any damage and misorientation. We also found that the optical and electrical characteristics improved after transfer due to decease in built-in stress. This simple and practical method is expected to greatly facilitate the development of transferrable full color GaN microLEDs on various substrates with either greatly reduced or no damage.
关键词： transfer,light emitting diode,chemical lift-o?,GaN
更新于2025-09-19 17:13:59
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Violet Light-Emitting Diodes Based on p-CuI Thin Film/n-MgZnO Quantum Dot Heterojunction
摘要： As the lighting technology evolves, the need for violet light-emitting diodes (LEDs) is growing for high color rendering index lighting. The present technology for violet LEDs is based on the high-cost GaN materials and metal?organic chemical vapor deposition process; therefore, there have recently been intensive studies on developing low-cost alternative materials and processes. In this study, for the ?rst time, we demonstrated violet LEDs based on low-cost materials and processes using a p-CuI thin ?lm/n-MgZnO quantum dot (QD) heterojunction. The p-CuI thin ?lm layer was prepared by an iodination process of Cu ?lms, and the n-MgZnO layer was deposited by spin-coating presynthesized n-MgZnO QDs. To maximize the performance of the violet LED, an optimizing process was performed for each layer of p- and n-type materials. The optimized LED with 1 × 1 mm2-area pixel fabricated using the p-CuI thin ?lm at the iodination temperature of 15 °C and the n-MgZnO QDs at the Mg alloying concentration of 2.7 at. % exhibited the strongest violet emissions at 6 V.
关键词： p-CuI thin ?lm,device optimization,violet light-emitting diode,heterojunction,n-MgZnO quantum dot
更新于2025-09-19 17:13:59
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Green-synthesized, low-cost tetracyanodiazafluorene (TCAF) as electron injection material for organic light-emitting diodes
摘要： Two electron-deficient azaacenes including di- and tetra-cyanodiazafluorene (DCAF and TCAF) with the advantages of deep lowest unoccupied molecular orbital (LUMO), green-synthesis, low-cost, simply purification method, excellent yields have been obtained, characterized and used as electron injection materials (EIMs) in three groups of electroluminescence devices. Device B with TCAF as EIM exhibited the best performance including turn-on voltage of 5.0 V, stronger maximum luminance intensity of 31,549 cd/m2, higher luminance efficiency of 62.34 cd/A and larger power efficiency of 21.74 lm/W which are 0.53, 6.7, 9.3 and 15.3 times than that of device A with DCAF as EIMs, respectively. The enhanced interfacial electron injection ability of TCAF than that of DCAF is supported by its better electron mobility in electron-only device, deeper LUMO (-4.52 eV), and stronger electronic affinity. Best external quantum efficiency of 16.56% was achieved with optimized thicknesses of TCAF as EIM and TPBi as electron transporting layer. As a new comer of acceptor family, TCAF would push forward organic electronics with more fascinating and significant applications.
关键词： Tetracyanodiazafluorene (TCAF),Organic light-emitting diode,Green-synthesis,Electron-injection material,Acceptor
更新于2025-09-19 17:13:59
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Quantum dot light-emitting diodes with an Al-doped ZnO anode
摘要： A study of a hybrid ZnCdSeS/ZnS quantum dot light-emitting diodes (QLEDs) device fabricated with indium tin oxide (ITO)-free transparent electrodes is presented. Al-doped zinc oxide (AZO) prepared by magnetron sputtering is adopted in anode transparent electrodes for green QLEDs with different sputtering pressures. The Kelvin probe force microscopy measurement shows that AZO has a work function of approximately 5.0 eV. The AZO/poly(ethylene-dioxythiophene)/polystyrenesulfonate (PEDOT:PSS) interface can be adjusted by the sputtering pressures, which was confirmed by the hole-only devices. The AZO films with low surface roughness can form a good AZO/PEDOT:PSS interface, which can increase the holes’ injection, and result in improved charge balance. The maximum current efficiency, luminance and external quantum efficiency of the optimized QLEDs devices under a sputtering pressure of 1 mTorr can achieve values of 50.75 cd/A, 102,500 cd/m2 and 12.94%, respectively.
关键词： radio-frequency magnetron sputtering,Al-doped zinc oxide,quantum light-emitting diode,transparent electrode
更新于2025-09-19 17:13:59
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Ca(Mg <sub/>0.8</sub> Al <sub/>0.2</sub> )(Si <sub/>1.8</sub> Al <sub/>0.2</sub> )O <sub/>6</sub> :Ce <sup>3+</sup> ,Tb <sup>3+</sup> Phosphors: Structure Control, Density-Functional Theory Calculation, and Luminescence Property for pc-wLED Application
摘要： A modified structure Ca(Mg0.8Al0.2)(Si1.8Al0.2)O6 (denoted as CMASO) from the evolution of CaMgSi2O6 (denoted as CMSO) codoped with Ce3+ and Tb3+ ions was designed successfully by solid reaction method for application in phosphor-converted white-light-emitting diode (pc-wLED). The Rietveld refinement of these two structures verified the changes derived from the replacement of some of the Mg2+ and Si4+ ions by Al3+ ions. The band gaps were calculated by density-functional theory (DFT) calculation method to verify the change of Al3+ ions replacing further, and the diffuse reflectance spectra (DRS) proved the veracity of the calculation result. The phosphors CMASO:Ce3+ showed blue emission excited by a wider excitation wavelength from 280 nm to 370 nm. The change of structure lead to the absorbable range broaden and the emission peak shifted to longer wavelength, compared with CMSO:Ce3+, although the amount of emitting center was the same. The reason for these phenomena was discussed in detail. The codoped phosphors CMASO:Ce3+,Tb3+ exhibited different emission colors from blue to green as the concentration of Tb3+ ions increased. Combined with commercial red phosphor CaAlSiN3:Eu2+ and ultraviolet LED (UV-LED) chips, the selected appropriate samples achieved white emission. The correlated color temperature (CCT) was 6137 K and the color rendering index (Ra) was 80.5, indicating that they could act as potential phosphors for possible applications in pc-wLED.
关键词： Ce3+,pc-wLED,DFT,luminescence property,Tb3+,Ca(Mg0.8Al0.2)(Si1.8Al0.2)O6,phosphor-converted white-light-emitting diode,density-functional theory
更新于2025-09-19 17:13:59
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Angular-Fused Dithianaphthylquinone Derivative: Selective Synthesis, Thermally Activated Delayed Fluorescence Property, and Application in Organic Light-Emitting Diode
摘要： A novel angular-fused dithianaphthylquinone derivative, f-TX-TPA, was designed and selectively synthesized. The regioselectivity of angular-fused reaction was interpreted by theoretical calculations. The f-TX-TPA compound displayed excellent thermally activated delayed ?uorescence property. Moreover, the organic light-emitting diodes (OLEDs) using f-TX-TPA as an emitter exhibited a high external quantum e?ciency of 15.9%. These results indicated that angular-fused dithianaphthylquinone derivatives could have great potential in the application of high-e?ciency OLEDs.
关键词： thermally activated delayed ?uorescence,organic light-emitting diode,angular-fused dithianaphthylquinone,high-e?ciency
更新于2025-09-19 17:13:59
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Ecological biosubstrates obtained from onion pulp ( <i>Allium cepa L.</i> ) for flexible organic light-emitting diodes
摘要： A new biopolymer obtained from onion pulp - Allium cepa L. - was employed to produce sustainable substrates for flexible organic light-emitting diodes (FOLEDs). Indium tin oxide (ITO) and SiO2 thin films were deposited by rf-magnetron sputtering onto these bio-substrates to obtain flexible, transparent and conductive anodes on top of which FOLEDs were produced. This new biomaterial exhibits optical transparency of 63 % at 550 nm. ITO films were optimized by varying rf-power during deposition onto the biopolymers and their electrical properties are comparable to the ones of ITO grown on top of rigid substrates: carrier concentration of -3.63 × 1021 cm?3 and carrier mobility of 7.72 cm2V-1s-1 for the optimized film. Consequently, the sheet-resistance and resistivity of this ITO film were 8.92 Ω□-1 and 2.23 × 10-4 Ωcm, respectively, hence allowing the production of FOLEDs. The Allium cepa L. based FOLED was fabricated using CuPc, β-NPB and Alq3 as organic layers, and it exhibited a maximum luminance of about 2062 cdm-2 at 16.6 V. The current efficiency reached a maximum value of 2.1 cdA-1 at 85.3 mAcm-2. The obtained results suggest the possibility to use these substrates for innovative biocompatible applications in optoelectronics, such as photodynamic therapy.
关键词： biosubstrate,Allium cepa L.,biopolymer,FOLED,flexible organic light-emitting diode
更新于2025-09-19 17:13:59
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A Novel Synchronous Current-Doubler Rectifier for LED Drivers Without Electrolytic Capacitors
摘要： High-brightness light-emitting diode (LED) lamps have attracted much attention because of their high efficiency, simple structure, energy conservation and environmental protection aspects, and long lifetime. Thus, an LED driver must have a long lifespan, high density, and compact space. However, conventional LED power supplies use an electrolytic capacitor as the storage capacitor in the holdup time, which has a short lifespan and occupies large space. In this paper, a novel synchronous current-doubler rectifier (SCDR) method is proposed as an LED driver. The reasonably designed circuit is used to control the output voltage ripple in the normal range without adding a complicated control circuit. The proposed topology is designed using few components, has no electrolytic capacitor, and has a low cost for high-output current LED driver applications. Circuit operating principles and detailed theoretical analysis are provided in this paper. A 200-W prototype has been established and tested, and the experimental results are presented to highlight the merits of the proposed circuit.
关键词： synchronous current-doubler rectifier (SCDR),LLC,light-emitting diode (LED),Electrolytic capacitor
更新于2025-09-19 17:13:59