scholarly journals Introductory Chapter: The Impression of Light-Emitting Diodes in Space-Age Advancements and Its Effect of Blue LED Irradiation

Author(s):  
Jagannathan Thirumalai
Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1477
Author(s):  
Woo-Suk Jung ◽  
Ill-Min Chung ◽  
Myeong Ha Hwang ◽  
Seung-Hyun Kim ◽  
Chang Yeon Yu ◽  
...  

Light is a key factor that affects phytochemical synthesis and accumulation in plants. Due to limitations of the environment or cultivated land, there is an urgent need to develop indoor cultivation systems to obtain higher yields with increased phytochemical concentrations using convenient light sources. Light-emitting diodes (LEDs) have several advantages, including consumption of lesser power, longer half-life, higher efficacy, and wider variation in the spectral wavelength than traditional light sources; therefore, these devices are preferred for in vitro culture and indoor plant growth. Moreover, LED irradiation of seedlings enhances plant biomass, nutrient and secondary metabolite levels, and antioxidant properties. Specifically, red and blue LED irradiation exerts strong effects on photosynthesis, stomatal functioning, phototropism, photomorphogenesis, and photosynthetic pigment levels. Additionally, ex vitro plantlet development and acclimatization can be enhanced by regulating the spectral properties of LEDs. Applying an appropriate LED spectral wavelength significantly increases antioxidant enzyme activity in plants, thereby enhancing the cell defense system and providing protection from oxidative damage. Since different plant species respond differently to lighting in the cultivation environment, it is necessary to evaluate specific wavebands before large-scale LED application for controlled in vitro plant growth. This review focuses on the most recent advances and applications of LEDs for in vitro culture organogenesis. The mechanisms underlying the production of different phytochemicals, including phenolics, flavonoids, carotenoids, anthocyanins, and antioxidant enzymes, have also been discussed.


RSC Advances ◽  
2021 ◽  
Vol 11 (42) ◽  
pp. 26415-26420
Author(s):  
Yue Yao ◽  
Si-Wei Zhang ◽  
Zijian Liu ◽  
Chun-Yun Wang ◽  
Ping Liu ◽  
...  

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).


2012 ◽  
Vol 26 (12) ◽  
pp. 1250071 ◽  
Author(s):  
YAN WANG ◽  
FUGEN WU ◽  
XIN ZHANG ◽  
YUANWEI YAO ◽  
HUILIN ZHONG ◽  
...  

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.


2013 ◽  
Vol 138 (1) ◽  
pp. 31-37 ◽  
Author(s):  
Dean A. Kopsell ◽  
Carl E. Sams

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.


2005 ◽  
Vol 892 ◽  
Author(s):  
Xian-An Cao ◽  
T. Stecher ◽  
S. LeBoeuf

AbstractThe performance of InGaN and AlGaN-based blue (465nm) and deep ultraviolet (UV) (280 nm) light-emitting diodes (LEDs) at elevated temperatures (25-175 °C) were investigated. As a result of uniform high-Al content AlGaN alloys yielded by migration-enhanced metalorganic chemical vapor deposition, the deep-UV LED showed dominant band-edge emission, much smaller alloy broadening and weaker localization effects as compared to the InGaN LED. Strong carrier localization was retained in the blue LED up to 175 °C, leading to temperature-independent emission intensity at low-energy tails. The UV LED, however, showed a much more rapid decrease in light output with increasing temperature. The characteristic temperature was 37 K, compared to 270 K for the blue LED. These findings implicate the lack of localization effects in AlGaN alloys as one of the causal factors in the poor thermal performance of the deep UV LED and suggest that increasing carrier confining potentials will provide a critical means to improve its thermal stability.


2004 ◽  
Vol 449-452 ◽  
pp. 953-956
Author(s):  
J.K. Park ◽  
Chang Hoi Kim ◽  
Kyung Joo Choi ◽  
H.D. Park ◽  
Se Young Choi

We have synthesized a Eu2+-activated Sr2SiO4yellow phosphor and investigated an attempt to develop white LEDs by combining it with a GaN blue LED chip. Two distinct emission bands from the GaN-based LED and the Sr2SiO4:Eu phosphor are clearly observed at 400 nm and at around 550 nm, respectively. These two emission bands combine to give a spectrum that appears white to the naked eye. Our results show that GaN (400 nm chip)-based Sr2SiO4:Eu exhibits a better luminous efficiency than that of the industrially available product InGaN (460 nm chip)-based YAG:Ce.


2015 ◽  
pp. 188-192
Author(s):  
Silvino Jose Antuña Presa

Light-emitting diodes also known as LEDs are all around us: they are used in TVs, computers, mobile phones, street lighting and even in our homes in the form of new energy saving and long lifespan lamps. Now you might be wondering: “why all the fuss? Is this another ‘new thing’ that is going to disappear in a couple of years or is this something that is going to stay?” Well, to the truth, LEDs have been around for some time: they were initially used as small indicator lamps and for small displays; in fact, almost any appliance you may have at home will have a small LED lamp to tell you whether it is on or off. Things started to change when the first blue LED was demonstrated in 1994. Before this achievement the only available colours for LEDs with decent efficiency were red and orange-red. This was good for ...


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