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.

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.

Performance of Arabidopsis thaliana under different light qualities: comparison of light-emitting diodes to fluorescent lamp

2017 ◽  
Vol 44 (7) ◽  
pp. 727 ◽  
Author(s):  
Karin Köhl ◽  
Takayuki Tohge ◽  
Mark Aurel Schöttler
Keyword(s):  
Arabidopsis Thaliana ◽  
Light Source ◽  
Light Emitting Diodes ◽  
Seed Mass ◽  
Fluorescent Light ◽  
Chlorophyll Fluorescence Parameters ◽  
Light Emitting ◽  
Led Light ◽  
Improve Energy Efficiency ◽  
Fluorescent Lamps

For precise phenotyping, Arabidopsis thaliana (L.) Heynh. is grown under controlled conditions with fluorescent lamps as the predominant light source. Replacement by systems based on light emitting diodes (LED) could improve energy efficiency and stability of light quality and intensity. To determine whether this affects the reproducibility of results obtained under fluorescent lamps, four Arabidopsis accessions and a phytochrome mutant were grown and phenotyped under two different LED types or under fluorescent lamps. All genotypes had significantly higher rosette weight and seed mass and developed faster under LED light than under fluorescent lamps. However, differences between genotypes were reproducible independent of the light source. Chlorophyll content, photosynthetic complex accumulation and light response curves of chlorophyll fluorescence parameters were indistinguishable under LED and fluorescent light. Principal component analysis of leaf metabolite concentrations revealed that the effect of a change from fluorescent light to LED light was small compared with the diurnal effect, which explains 74% of the variance and the age effect during vegetative growth (12%). Altogether, the replacement of fluorescent lamps by LED allowed Arabidopsis cultivation and reproduction of results obtained under fluorescent light.

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

scholarly journals Demonstration of epitaxial growth of strain-relaxed GaN films on graphene/SiC substrates for long wavelength light-emitting diodes

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Ye Yu ◽  
Tao Wang ◽  
Xiufang Chen ◽  
Lidong Zhang ◽  
Yang Wang ◽  
...  
Keyword(s):  
Epitaxial Growth ◽  
Light Emitting Diodes ◽  
Nitrogen Plasma ◽  
Biaxial Stress ◽  
Organic Chemical ◽  
Graphene Surface ◽  
Light Emitting ◽  
Long Wavelength ◽  
Pre Treatment ◽  
Wavelength Light

AbstractStrain modulation is crucial for heteroepitaxy such as GaN on foreign substrates. Here, the epitaxy of strain-relaxed GaN films on graphene/SiC substrates by metal-organic chemical vapor deposition is demonstrated. Graphene was directly prepared on SiC substrates by thermal decomposition. Its pre-treatment with nitrogen-plasma can introduce C–N dangling bonds, which provides nucleation sites for subsequent epitaxial growth. The scanning transmission electron microscopy measurements confirm that part of graphene surface was etched by nitrogen-plasma. We study the growth behavior on different areas of graphene surface after pre-treatment, and propose a growth model to explain the epitaxial growth mechanism of GaN films on graphene. Significantly, graphene is found to be effective to reduce the biaxial stress in GaN films and the strain relaxation improves indium-atom incorporation in InGaN/GaN multiple quantum wells (MQWs) active region, which results in the obvious red-shift of light-emitting wavelength of InGaN/GaN MQWs. This work opens up a new way for the fabrication of GaN-based long wavelength light-emitting diodes.

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).

scholarly journals Utjecaj različitog tipa umjetnog osvjetljenja na klijavost sjemena matovilca i kres salate

2017 ◽  
Vol 40 (6) ◽  
pp. 70-76
Author(s):  
Tomislav Vinković ◽  
Monika Tkalec ◽  
Nada Parađiković ◽  
MIro Stošić ◽  
Krunoslav Zmaić ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Light Emitting ◽  
Led Light

Cilj rada je bio utvrditi utjecaj LED (Light Emitting Diodes) i FLUO (fluorescentno svjetlo) osvjetljenja na klijavost i energiju klijanja sjemena te masu i visinu klijanaca matovilca i kres salate. Sjetva naturalnog sjemena provedena je u Petrijeve zdjelice u komori opremljenoj LED i FLUO lampama. LED lampe su bile opremljene crvenim (650-670 nm) i plavim (440-460 nm) LED diodama u omjeru 3:1. Istraživanje je provedeno u Laboratoriju za povrćarstvo, cvjećarstvo, ljekovito i začinsko bilje Poljoprivrednog fakulteta u Osijeku. Utvrđen je statistički opravdan utjecaj tipa osvjetljenja na energiju klijanja i klijavost sjemena matovilca, a veće vrijednosti utvrđene su uslijed primjene LED lampi. Suprotno, pod FLUO lampama je utvrđena značajno veća masa i visina klijanaca matovilca te visina klijanaca kres salate. Međutim, tip osvjetljenja nije značajno utjecao na klijavost i energiju klijanja te masu klijanaca kres salate. Prema tome, može se zaključiti da je odgovor na tip osvjetljenja uvjetovan biljnom vrstom već od samih početaka rasta i razvoja.

scholarly journals Compressive strength measurements of hybrid dental composites treated with dry heat and light emitting diodes (LED) post cure treatment

2014 ◽  
Vol 26 (3) ◽  
Author(s):  
Jenny Krisnawaty ◽  
Setiawan Natasasmita ◽  
Dudi Aripin
Keyword(s):  
Compressive Strength ◽  
Hybrid Composite ◽  
Light Emitting Diodes ◽  
Composite Resin ◽  
Hybrid Composites ◽  
Testing Machine ◽  
Dental Composite ◽  
Light Emitting ◽  
Led Light ◽  
Dry Heat

Hybrid composites are mostly used on large cavities as restorative dental materials, whether it is used directly or indirectly. The mechanical properties of composite resin shall increase if it is treated with post cure treatment. The aim of this study is to evaluate compressive strength differences between dry heat and Light Emitting Diodes (LED) treatment on the hybrid dental composite. A quasi-experimental was applied on this research with a total of 30 samples that were divided into two groups. Each sample was tested using LLOYD Universal Testing Machine with 1 mm/min speed to evaluate the compressive strength. The compressive strength results were marked when the sample was broken. The results of two groups were then analyzed using t-test statistical calculation. The results of this study show that post cure treatment on hybrid composite using LED light box (194.138 MPa) was lower than dry heat treatment (227.339 MPa), which was also significantly different from statistical analysis. It can be concluded that compressive strength of LED light box was lower than dry heat post-cure treatment on the hybrid composite resin.

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