scholarly journals Increases in Shoot Tissue Pigments, Glucosinolates, and Mineral Elements in Sprouting Broccoli after Exposure to Short-duration Blue Light from Light Emitting Diodes

2013 ◽  
Vol 138 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Dean A. Kopsell ◽  
Carl E. Sams
Keyword(s):  
Blue Light ◽  
Short Duration ◽  
Light Emitting Diodes ◽  
Mineral Elements ◽  
Light Emitting ◽  
Blue Led ◽  
Led Light ◽  
Shoot Tissue ◽  
Phytochemical Compounds ◽  
The Impact

Microgreens are specialty leafy crops harvested just above the roots after the first true leaves have emerged and are consumed fresh. Broccoli (Brassica oleacea var. italica) microgreens can accumulate significant concentrations of cancer-fighting glucosinolates as well as being a rich source of other antioxidant phytochemicals. Light-emitting diodes (LEDs) now provide the ability to measure impacts of narrow-band wavelengths of light on seedling physiology. The carotenoid zeaxanthin has been hypothesized to be a blue light receptor in plant physiology. The objective of this study was to measure the impact of short-duration blue light on phytochemical compounds, which impart the nutritional quality of sprouting broccoli microgreens. Broccoli microgreens were grown in a controlled environment under LEDs using growing pads. Seeds were cultured on the pads submerged in deionized water and grown under a 24-hour photoperiod using red (627 nm)/blue (470 nm) LEDs (350 μmol·m−2·s−1) at an air temperature of 23 °C. On emergence of the first true leaf, a complete nutrient solution with 42 mg·L−1 of nitrogen (N) was used to submerge the growing pads. At 13 days after sowing, broccoli plantlets were grown under either: 1) red and blue LED light (350 μmol·m−2·s−1); or 2) blue LED light (41 μmol·m−2·s−1) treatments for 5 days before harvest. The experiment was repeated three times. Frozen shoot tissues were freeze-dried and measured for carotenoids, chlorophylls, glucosinolates, and mineral elements. Comparing the two LED light treatments revealed the short-duration blue LED treatment before harvest significantly increased shoot tissue β-carotene (P ≤ 0.05), violaxanthin (P ≤ 0.01), total xanthophyll cycle pigments (P ≤ 0.05), glucoraphanin (P ≤ 0.05), epiprogoitrin (P ≤ 0.05), aliphatic glucosinolates (P ≤ 0.05), essential micronutrients of copper (Cu) (P = 0.02), iron (Fe) (P ≤ 0.01), boron (B), manganese (Mn), molybdenum (Mo), sodium (Na), zinc (Zn) (P ≤ 0.001), and the essential macronutrients of calcium (Ca), phosphorus (P), potassium (K), magnesium (Mg), and sulfur (S) (P ≤ 0.001). Results demonstrate management of LED lighting technology through preharvest, short-duration blue light acted to increase important phytochemical compounds influencing the nutritional value of broccoli microgreens.

scholarly journals Air stable and highly efficient Bi3+-doped Cs2SnCl6 for blue light-emitting diodes

RSC Advances ◽  
2021 ◽  
Vol 11 (42) ◽  
pp. 26415-26420
Author(s):  
Yue Yao ◽  
Si-Wei Zhang ◽  
Zijian Liu ◽  
Chun-Yun Wang ◽  
Ping Liu ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Blue Light ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Color Coordinates ◽  
Blue Led ◽  
Highly Efficient ◽  
Photoluminescence Quantum Yield ◽  
Long Life

A Bi3+-doped Cs2SnCl6 exhibits photoluminescence at around 456 nm and a photoluminescence quantum yield of 31%. The blue LED based on the Bi3+-doped Cs2SnCl6 phosphor exhibits a long life of 120 hours and a CIE color coordinates of (0.14, 0.11).

Studies of Degradation in Nichia AlGaN/InGaN/GaN Blue Light Emitting Diodes Under Close to Normal Operating Conditions

1996 ◽  
Vol 421 ◽  
Author(s):  
M. Osiński ◽  
D. L. Barton ◽  
C. J. Helms ◽  
P. Perlin ◽  
N. H. Berg ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diodes ◽  
Defect Density ◽  
Degradation Process ◽  
Operating Conditions ◽  
Similar Amount ◽  
Life Testing ◽  
Light Emitting ◽  
High Pulsed Current ◽  
The Impact

AbstractThe reliability of devices fabricated in GaN and related alloys, especially under high current densities as would be found in lasers, has yet to be fully characterized. Our previous work [1] investigated the degradation of GaN-based blue light emitting diodes (LEDs) under high pulsed current stress. This work indicated a possible correlation between the high crystal defect density and failures caused by metal migration along these defect tubes. To assess the impact of this data on devices under more normal conditions, several LEDs from both older and more recent production lots were placed in a controlled temperature and current environment for several thousand hours. The test started with a constant 20 mA current for the first 1000 hours and continued for another 1650 hours at various currents up to 70 mA, all at a temperature of 23 °C. During this test, one of the older generation LED's output degraded by more than 50%. Subsequent failure analysis showed that this was caused by a crack which isolated part of the active region from the p-contact. The remaining LEDs were returned to life testing where the temperature was subsequently increased by 5 °C after each 500 hours of testing. The output from one of the newer LEDs dreiven at 70 mA degraded to 55% of its original value after 3600 hours and a second newer LED degraded by a similar amount after 4400 hours. The first failure, LED #16, did not exhibit a significant change in its I-V characteristics indicating that a change in the package transparency was a likely cause for the observed degradation. The second failure, LED #17, did show a noticeable change in its I-V characteristics. This device was subsequently returned to life testing where the degradation process will be monitored for further changes.

ENHANCEMENT OF LIGHT EXTRACTING FROM GaN-BASED BLUE LIGHT EMITTING DIODES USING PHOTONIC CRYSTAL

2012 ◽  
Vol 26 (12) ◽  
pp. 1250071 ◽  
Author(s):  
YAN WANG ◽  
FUGEN WU ◽  
XIN ZHANG ◽  
YUANWEI YAO ◽  
HUILIN ZHONG ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Blue Light ◽  
Light Emitting Diodes ◽  
Light Energy ◽  
Light Extraction ◽  
Light Emitting ◽  
Blue Led ◽  
Defect Area

Photonic crystal (PC) structures on LED have been known to enhance the light extraction significantly. In this paper, we report the light energy of GaN -based blue lighting emitting diode (LED) with perfect area photonic crystal (PPC) structure and defect area photonic crystal (DPC) structure. As a result, the light extracting energy of LEDs with PPC structure enhanced little compared to that of without PC structure. In addition, the light extracting energy of blue LED with DPC structure was remarkably improved.

scholarly journals The Proportion of Blue Light from Light-emitting Diodes Alters Microgreen Phytochemical Profiles in a Species-specific Manner

HortScience ◽  
2021 ◽  
Vol 56 (1) ◽  
pp. 13-20
Author(s):  
Qinglu Ying ◽  
Chase Jones-Baumgardt ◽  
Youbin Zheng ◽  
Gale Bozzo
Keyword(s):  
Blue Light ◽  
Light Emitting Diodes ◽  
Red Light ◽  
Total Carotenoids ◽  
Total Anthocyanin ◽  
Light Emitting ◽  
Red Cabbage ◽  
Species Specific ◽  
A Minor ◽  
The Impact

Microgreens are specialty vegetables that contain human health-promoting phytochemicals. Typically, microgreens are cultivated in controlled environments under red and blue light-emitting diodes (LEDs). However, the impact of varying the proportions of these light qualities on the composition of diverse phytochemicals in indoor-grown microgreens is unclear. To address this problem, the levels of chlorophylls, carotenoids, ascorbates, phenolics, anthocyanins, and nitrate were examined in arugula (Eruca sativa L.), ‘Red Russian’ kale [Brassica napus L. subsp. napus var. pabularia (DC.) Alef.], ‘Mizuna’ mustard (Brassica juncea L.), and red cabbage (Brassica oleracea L. var. capitata f. rubra) microgreens following cultivation under LEDs supplying varying proportions of blue light (5% to 30%) and red light (70% to 95%). Varying the proportion of blue light did not affect the extractable levels of total chlorophyll, total carotenoids, or nitrate in all four microgreen species. Generally, the levels of reduced and total ascorbate were greatest in arugula, kale, and mustard microgreens at 20% blue light, and a minor decrease was apparent at 30% blue light. These metabolite profiles were not impacted by the blue light percentage in red cabbage. Kale and mustard accumulated more total phenolics at 30% blue light than all other blue light regimens; however, this phytochemical attribute was unaffected in arugula and red cabbage. The total anthocyanin concentration increased proportionally with the percentage of supplied blue light up to 30% in all microgreens, with the exception of mustard. Our research showed that 20% blue light supplied from LED arrays is ideal for achieving optimal levels of both reduced and total ascorbate in all microgreens except red cabbage, and that 30% blue light promotes the greatest accumulation of total anthocyanin in indoor-grown Brassicaceae microgreens, with the exception of mustard.

Blue LED (light-emitting diodes)-mediated growth promotion and control ofBotrytisdisease in lettuce

2013 ◽  
Vol 63 (3) ◽  
pp. 271-277 ◽  
Author(s):  
Hee-Sun Kook ◽  
Sung-Hee Park ◽  
Ye-Jin Jang ◽  
Gun-Woong Lee ◽  
Jae Su Kim ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Growth Promotion ◽  
Light Emitting ◽  
Blue Led ◽  
Led Light ◽  
And Control

Blue light from light-emitting diodes elicits a dose-dependent suppression of melatonin in humans

2011 ◽  
Vol 110 (3) ◽  
pp. 619-626 ◽  
Author(s):  
Kathleen E. West ◽  
Michael R. Jablonski ◽  
Benjamin Warfield ◽  
Kate S. Cecil ◽  
Mary James ◽  
...  
Keyword(s):  
Short Wavelength ◽  
Healthy Subjects ◽  
Response Curve ◽  
Light Emitting Diodes ◽  
Fluorescent Light ◽  
Light Emitting ◽  
Blue Led ◽  
Led Light ◽  
Melatonin Suppression ◽  
Wavelength Light

Light suppresses melatonin in humans, with the strongest response occurring in the short-wavelength portion of the spectrum between 446 and 477 nm that appears blue. Blue monochromatic light has also been shown to be more effective than longer-wavelength light for enhancing alertness. Disturbed circadian rhythms and sleep loss have been described as risk factors for astronauts and NASA ground control workers, as well as civilians. Such disturbances can result in impaired alertness and diminished performance. Prior to exposing subjects to short-wavelength light from light-emitting diodes (LEDs) (peak λ = 469 nm; ½ peak bandwidth = 26 nm), the ocular safety exposure to the blue LED light was confirmed by an independent hazard analysis using the American Conference of Governmental Industrial Hygienists exposure limits. Subsequently, a fluence-response curve was developed for plasma melatonin suppression in healthy subjects ( n = 8; mean age of 23.9 ± 0.5 years) exposed to a range of irradiances of blue LED light. Subjects with freely reactive pupils were exposed to light between 2:00 and 3:30 AM. Blood samples were collected before and after light exposures and quantified for melatonin. The results demonstrate that increasing irradiances of narrowband blue-appearing light can elicit increasing plasma melatonin suppression in healthy subjects ( P < 0.0001). The data were fit to a sigmoidal fluence-response curve ( R2 = 0.99; ED50 = 14.19 μW/cm2). A comparison of mean melatonin suppression with 40 μW/cm2 from 4,000 K broadband white fluorescent light, currently used in most general lighting fixtures, suggests that narrow bandwidth blue LED light may be stronger than 4,000 K white fluorescent light for suppressing melatonin.

Blue light-emitting diodes in hair regrowth: the first prospective study

2021 ◽  
Author(s):  
G. Lodi ◽  
M. Sannino ◽  
G. Cannarozzo ◽  
A. Giudice ◽  
E. Del Duca ◽  
...  
Keyword(s):  
Prospective Study ◽  
Blue Light ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Hair Regrowth

scholarly journals Device Modeling of Quantum Dot–Organic Light Emitting Diodes for High Green Color Purity

2021 ◽  
Vol 11 (6) ◽  
pp. 2828
Author(s):  
Byoung-Seong Jeong
Keyword(s):  
Quantum Dot ◽  
Emission Spectrum ◽  
Blue Light ◽  
Light Emitting Diodes ◽  
Organic Light Emitting Diodes ◽  
Color Purity ◽  
Wavelength Band ◽  
Light Emitting ◽  
Green Color ◽  
Organic Light

In this study, the optimal structure for obtaining high green color purity was investigated by modeling quantum dot (QD)–organic light-emitting diodes (OLED). It was found that even if the green quantum dot (G-QD) density in the G-QD layer was 30%, the full width at half maximum (FWHM) in the green wavelength band could be minimized to achieve a sharp emission spectrum, but it was difficult to completely block the blue light leakage with the G-QD layer alone. This blue light leakage problem was solved by stacking a green color filter (G-CF) layer on top of the G-QD layer. When G-CF thickness 5 μm was stacked, blue light leakage was blocked completely, and the FWHM of the emission spectrum in the green wavelength band was minimized, resulting in high green color purity. It is expected that the overall color gamut of QD-OLED can be improved by optimizing the device that shows such excellent green color purity.

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