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Realization of Excitation Wavelength Independent Blue Emission of ZnO Quantum Dots with Intrinsic Defects
摘要： Eco-friendly cation metal oxide quantum dots (QDs) are one of promising candidates to replace for QDs containing expensive Indium (In) or hazardous Cd- and Pb-elements. Super-Eg excitation wavelength (λex) dependent Zni-VO complex defects related characteristic emissions of green, yellow, and orange-red from ZnO QDs are completely inhibited by reducing oxygen vacancies through the hybridization of Zn interstitials in ZnO QDs with anti-bonding O-states of graphene oxide (GO) QDs. Thus, only λex independent violet-purple-blue (V-P-B) emission resulting from transitions among Frenkel pairs (Zni 0-VZn) and the defects Zni 0-Oi in ZnO-GO QDs with a high photoluminescence quantum yield (PLQY) of 92% is successfully achieved. White-light emission from PL QD-LEDs is achieved using a mixture of ZnO and ZnO-GO QDs with CIE (0.32, 0.34) excited by a UV LEDs chip (λ=365 nm). Further, ZnO-GO QD-based deep-blue LEDs (λ=438 nm) with luminance of 1980 cd/m2, a luminous efficacy (LE) of 2.53 cd/A, and external quantum efficiency (EQE) of 2.78 % with CIE (0.16, 0.11) are also realized.
关键词： eco-friendly fluorescent materials,excitation independent deep blue light emission,photoluminescence quantum efficiency,Zni-Vo complex defects,ZnO-Graphene Oxide quantum dots
更新于2025-09-19 17:13:59
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New cyanopyridine based conjugated polymers carrying auxiliary electron donors: From molecular design to blue emissive PLEDs
摘要： Three new D-A (Donor-Acceptor) configured conjugated polymers, i.e. PPy1-3, centered on strong electron accepting cyanopyridine scaffold carrying varied auxiliary donors, viz. phenylene (PPy1), biphenyl (PPy2), and fluorene (PPy3) were designed and synthesized as blue emitters for PLEDs. The new polymers were subjected to spectral, thermal, photophysical and electrochemical characterization. Also, computational studies (DFT) were performed on the repeating units of polymer using Turbomole 7.2V software package at the B3LYP/TZVP hybrid levels. Further, their weight average molecular masses were found to be 38.8 kDa, 38.9 kDa and 57.7 kDa, respectively as determined by GPC technique. Furthermore, the new polymers PPy1-3, were shown to be stable thermally up to 308-347 ?C. Evidently, they exhibited good photophysical behavior with their optical energy band gaps of 2.53-2.63 eV. Finally, the polymers PPy1-3 were employed as an active emissive layer in standard ITO/PEDOT:PSS/Polymer/Al configured PLEDs. Interestingly, at 12 V all the newly fabricated devices exhibit a stable blue characteristic electroluminescence with low threshold voltages of 3.40-5.20 V, confirming an efficient injection of electrons in the diodes. From the results, it is clear that, the polymers PPy1-3, can be considered as prospective blue light emitters for PLED application.
关键词： Donor-Acceptor,DFT,Cyanopyridine,Electroluminescence,Blue light emitter
更新于2025-09-16 10:30:52
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A Randomized, Vehicle-Controlled Phase 3 Study of Aminolevulinic Acid Photodynamic Therapy for the Treatment of Actinic Keratoses on the Upper Extremities
摘要： BACKGROUND Blue-light aminolevulinic acid photodynamic therapy (ALA-PDT) after broad-area application and 3-hour incubation is ef?cacious for actinic keratosis (AK) lesion clearance on upper extremities, with use of occlusive dressing signi?cantly increasing ef?cacy. OBJECTIVE To prove the safety and ef?cacy of ALA-PDT versus vehicle (VEH-PDT) in the spot treatment of multiple AKs on upper extremities. METHODS Aminolevulinic acid or VEH was spot applied only to lesions on one upper extremity 3 hours before blue-light exposure. Treated extremity was covered with occlusive dressing during incubation. Identical treatment was repeated at Week 8 if AK lesions were present in the treated area. RESULTS Thirty-one percent (42/135) of subjects treated with ALA-PDT had complete clearance at Week 12, compared with 13% (17/134) of the subjects treated with VEH-PDT (p = .0001). The mean AK lesion clearance rate for ALA-treated subjects at Weeks 8 and 12 was 53% and 69%, respectively, compared with 26% and 30% for the VEH-treated group (p < .0001, linear mixed model). Safety pro?le observed in this study is consistent with previous studies/reports in the literature, and the therapy was well tolerated overall. CONCLUSION Aminolevulinic acid-PDT spot treatment using a 3-hour occluded incubation was superior to VEH-PDT for AK lesion clearance of the upper extremity.
关键词： actinic keratosis,photodynamic therapy,aminolevulinic acid,upper extremities,blue light
更新于2025-09-16 10:30:52
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New Class of Supramolecular Bowl-Shaped Columnar Mesogens Derived from Thiacalix[4]arene Exhibiting Gelation and Organic Light-Emitting Diodes Applications
摘要： A new class of blue light-emitting bowl-shaped mesogens with the thiacalix[4]arene core appended with 1,3,4-thiadiazole derivatives having peripheral alkoxy side chains have been synthesized and well characterized. The liquid crystalline behavior of present synthesized derivatives was examined by optical polarizing microscopy, di?erential scanning calorimetry, and X-ray di?raction studies. It was observed that these thiacalix[4]arene derivatives were capable of stabilizing the observed Colh phase with a higher temperature range. The cone-shaped thiacalix[4]-arene-based liquid crystals with peripheral alkoxy side chains able to pack into the interactions and thermal behavior. All derivatives showed blue luminescence in solution, solid thin-?lm, and gelation state. The hexagonal columnar phase and emissive nature of thiadiazole-based thiacalixarene compounds having xerogel behavior make them favorable in the application of emissive electronic display devices. The electrochemical properties of these thiacalixarene-based compounds demonstrate the e?ect of alkyl side chain on the highest occupied molecular orbital?lowest unoccupied molecular orbital energy levels and also exhibited lower electron band gaps. The electroluminescence behavior of the compound 10c was examined as emissive layers in the fabrication of organic light-emitting diodes.
关键词： thiacalix[4]arene,bowl-shaped mesogens,blue light-emitting,organic light-emitting diodes,1,3,4-thiadiazole derivatives,liquid crystalline behavior
更新于2025-09-12 10:27:22
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Blue LED light irradiation enhances L-ascorbic acid content while reducing reactive oxygen species accumulation in Chinese cabbage seedlings
摘要： Chinese cabbage is one of the most representative vegetables in Southeast Asia and a main source of L-Ascorbic acid (AsA) for the human diet. In this study, we applied di?erent light qualities (red, blue and white) supported by light-emitting diode (LED) device to enhance AsA content in Chinese cabbage (Brassica rapa ssp. pekinensis) seedlings. Based on our results, blue LED light irradiation with an intensity of 125 μmol m?2s?1 increased the AsA content of ?ve-day-grown Chinese cabbage seedlings by 40% compared with white LED light irradiation. Accordingly, blue LED light irradiation induced expression of the AsA biosynthetic- and recycling-related genes. Interestingly, the reactive oxygen species (ROS) content of Chinese cabbage seedlings was decreased by blue LED light irradiation. In addition, the technology improving AsA content by blue LED light irradiation was applicable to other edible vegetable sprouts as well as to Chinese cabbage sprouts. Conclusively, our report introduces a source technology for arti?cially improving the AsA content of Chinese cabbage seedlings by applying blue LED light, which implies that application of certain types of LED light enables on-purpose cultivation of crops.
关键词： Chinese cabbage,Blue light,Ascorbic acid (AsA),Light-emitting diode (LED),Antioxidant
更新于2025-09-12 10:27:22
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Variations of Saponarin Content in Young Barley Leaves Illuminated with Different Light-Emitting Diodes (LEDs)
摘要： In this study, the effect of light on the regulation of flavonoid production in young barley leaves (YBLs) was investigated. YBLs following germination were illuminated with different light-emitting diode (LED) lights, i.e. blue, red, far-red light, along with fluorescence and dark conditions as controls, and as the main flavonoid, saponarin content of YBLs was analyzed quantitatively with HPLC. In addition, the antioxidant activities of the crude ethanoic extracts of YBLs were analyzed by several antioxidant assays. The content of saponarin in blue light-illuminated barley leaves is two or three times higher than those in barley leaves with other lighting conditions, i.e. red, far-red, and the content with fluorescence and even dark conditions as controls. However, the levels of saponarin among the leaves illuminated with other lighting systems show no significant difference. And, the antioxidant potentials of the extracts of YBLs demonstrated same tendency shown in saponarin levels. Our results suggested that blue lighting conditions might evoke the photoprotection changes in YBLs, leading elevated level of saponarin, consequently increasing their antioxidant potentials.
关键词： blue light,Young barley leaves,saponarin,LEDs,sprout
更新于2025-09-12 10:27:22
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Tunable Spreading and Shrinking on Photocontrolled Liquid Substrate
摘要： Droplets of n-hexadecane were observed to shrink under ultraviolet (365 nm) and spread under blue light (475 nm) irradiation on an aqueous solution of photosensitive surfactant AzoTAB. We demonstrate that the change of wettability of n-hexadecane droplet on the solution depends on the change of oil?water interface tension. According to the addition of ethanol into the substrate, the change of relative diameter ΔD/D exceeds 20%, much larger than the system without ethanol. With light-emitting diode (LED) light as a sole power source, without any other triggers, we provide a contactless and isothermal method to realize photocontrolled alternative spreading and shrinking of a droplet on a liquid surface, which provides a basis for a chromocapillary-based optical zoom liquid lens.
关键词： photosensitive surfactant AzoTAB,oil?water interface tension,optical zoom liquid lens,n-hexadecane,UV/blue light irradiation,chromocapillary effect
更新于2025-09-12 10:27:22
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Evaluation of Light-Emitting Diodes’ Effects on the Expression Level of P53 and EGFR in the Gingival Tissues of Albino Rats
摘要： Background and objectives: The light-curing unit is considered an essential piece of equipment in every dental office. This study was conducted to evaluate the effect of Light-Emitting Diodes (LEDs) by the light cure (LC) device on gingival tissues of albino rats histologically and by regarding the expression of P53 and epidermal growth factor receptor (EGFR). Materials and methods: Gingival tissues of the rats were exposed to LEDs for 30 s with an interval of 30 s for periods of 2 and 5 min and were examined after two and four weeks of light exposure. After the set time, histological sections were studied and the P53 and EGFR expressions were evaluated immunohistochemically and by molecular methods. Results: Mild hyperplasia and mild inflammatory response were detected in higher rates after two weeks of exposure when compared to 4 weeks postexposure. Whereas fibrosis was found at a higher rate after four weeks than that found after two weeks postexposure, parakeratosis was seen only in the group that was exposed for 5 min to LC and when biopsies were taken after 2 weeks. We found that the immunohistochemical expression of P53 was not changed. Similarly, the alteration of EGFR expression was statistically nonsignificant (p > 0.05) when compared to the control group. The data obtained from the qRT-PCR reaction was analyzed using the comparative CT (2???CT) method. Statistically, there was no significant difference in the expression of EGER and P53 gene transcripts. Conclusions: LED causes no serious alteration in P53 and EGFR expression, and only trivial histopathological changes occurred, most of which recovered after a 4-week interval.
关键词： P53,qRT-PCR,EGFR,dental curing lights,blue light hazard
更新于2025-09-12 10:27:22
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752 Clinical effects of LED blue light on skin pigmentation and carotenoid depletion
摘要： The growing evidence that visible light - and especially blue light - contributes to detrimental effects of sun exposure to skin, is becoming a subject of controversial debate nowadays. In this study we aimed to assess blue light-induced pigmentation and carotenoid depletion in vivo. Furthermore, we wanted to show a protective effect of SPF50 sunscreen formulations in a double-blind, placebo-controlled trial. The UVA/B filter system included the microfine particles titanium dioxide and methylene bis-benzotriazolyl tetramethylbutylphenol that extend effectiveness into the blue light range. Comparisons between repetitive irradiation with LED blue light (450 ± 20 nm) with 45 J/cm2 over 5 consecutive days after daily product application (2 mg/cm2) and irradiation only once with 135 J/cm2 after product application over 6 days were performed on the back of the volunteers. The extent of pigmentation and carotenoid depletion was investigated with the assessment of the skin color (ITA°) by chromameter measurements and the in vivo carotenoid concentration via multiple spatially resolved reflectance spectroscopy, respectively. Assessments were performed 5 hours, 24 hours, 1 week and 2 weeks after the last irradiation. Fourteen subjects terminated the study. Both, the single high-dose and the repetitive exposure resulted in comparable, immediate (≤5h) increase of skin pigmentation and carotenoid degradation (p<0.001). Skin pigmentation and carotenoid depletion attenuated on all test conditions already one day after the last irradiation. Both effects were still evident one and two weeks after the last irradiation. The application of the cosmetic formulations including UV pigments that scatter in the blue light range significantly reduced pigmentation (p<0.001) right after irradiation that might be considered for holistic light protection beyond UV.
关键词： carotenoid depletion,SPF50 sunscreen,UVA/B filter system,skin pigmentation,blue light
更新于2025-09-12 10:27:22
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OLEDs with Candle-Like Emission
摘要： Candle-like organic light-emitting diodes (OLEDs) emit much less blue light than other non-incandescent light sources. This type of OLED is characterized by low correlated color temperature (CCT), chromaticity tunability, and low melatonin (MLT) suppression. The light evokes a sense of warmth and creates a pleasant and calming ambience with its high-quality diffuse orange-red emission.
关键词： OLEDs,Color Temperature,Candle-Like Emission,Blue Light,Melatonin Suppression
更新于2025-09-12 10:27:22