Light Emitting Diodes (LED) for Aqueous Light Bleaching of Paper

Abstract High performance daylight LED lamps are compared with HID lamps for light bleaching of paper. The LED can be placed in closer proximity to the object than the HID lamps, causing a significantly increased, uniform light exposure. Two commercial LED systems with 4000 K and 6500 K colour temperature were installed in a convertible test device with a polypropylene tray in default exposure distance of 10 cm and 20 cm. A HID lamp in 60 cm and 120 cm distance served as a reference. Samples of two naturally aged rag papers were bleached with both LED systems and with the HID while immersed in water. All three light sources increased brightness (CIELAB L*), though the LEDs with 4000 K colour temperature were most effective. They had no negative effect on the molar mass and the cellulose carbonyl group content while LEDs with 6500 K colour temperature caused molar mass decrease and carbonyl group increase. LEDs of a 4000 K or similar colour temperature are a promising option for improved light bleaching of paper, reducing the treatment and aqueous exposure time and eliminating UV radiation.

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Electrically driven single microribbon based near-infrared exciton-polariton light-emitting diode

CrystEngComm ◽

10.1039/d1ce00419k ◽

2021 ◽

Author(s):

Mingming Jiang ◽

Fupeng Zhang ◽

Kai Tang ◽

Peng Wan ◽

Caixia Kan

Keyword(s):

High Performance ◽

Near Infrared ◽

Light Emitting Diodes ◽

Light Emitting Diode ◽

Light Sources ◽

Coherent Light ◽

Light Emitting ◽

Exciton Polaritons ◽

Laser Devices

Achieving electrically-driven exciton-polaritons has drawn substantial attention toward developing ultralow-threshold coherent light sources, containing polariton laser devices and high-performance light-emitting diodes (LEDs). In this work, we demonstrate an electrically driven...

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Effects of Different Colored LEDs on the Enhancement of Biologically Active Ingredients in Callus Cultures of Gynura procumbens (Lour.) Merr.

Molecules ◽

10.3390/molecules24234336 ◽

2019 ◽

Vol 24 (23) ◽

pp. 4336 ◽

Cited By ~ 4

Author(s):

Thang Tung Lian ◽

Se-Yeoun Cha ◽

Myat Myat Moe ◽

Yong Ju Kim ◽

Keuk Soo Bang

Keyword(s):

Liquid Chromatography ◽

High Performance ◽

Leaf Explants ◽

Callus Cultures ◽

Biologically Active ◽

Naphthaleneacetic Acid ◽

Light Sources ◽

Light Emitting ◽

Fluorescent Lamps ◽

Wavelength Emission

Conventional fluorescent lamps that are used in tissue culture are costly light sources, exhibiting excessive wavelength emission-bandwidth that must be replaced by alternative, less costly, and much lower power-consuming energy sources. The use of Light-Emitting Diodes (LEDs) is the best option due to their potential role as elicitors of secondary metabolite production in many plant models. Gynura procumbens (G. procumbens) is widely used for treating various diseases. Here, leaf explants were cultivated in MS medium that was supplemented with 0.5 mg/L of naphthaleneacetic acid (NAA) and 2.0 mg/L of benzylaminopurine (BAP) for 30 days under white, blue, and red LEDs. Secondary metabolites were analyzed by High Performance Liquid Chromatography (HPLC) and Liquid Chromatography-Mass Spectrometry (LC-MS). Blue LEDs elicited the highest antioxidant activity, total flavonoid, and phenolic content. Furthermore, the content of cyanidin-monoglucosides significantly increased under blue light.

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LED life prediction based on lumen depreciation and colour shift

Lighting Research and Technology ◽

10.1177/1477153515593580 ◽

2016 ◽

Vol 49 (1) ◽

pp. 84-99 ◽

Cited By ~ 4

Author(s):

AN Padmasali ◽

SG Kini

Keyword(s):

Life Prediction ◽

Energy Savings ◽

Light Emitting Diode ◽

Light Output ◽

Light Sources ◽

Colour Stability ◽

Light Emitting ◽

Colour Temperature ◽

Life Estimation ◽

Chromaticity Coordinates

Light emitting diodes, with advantages in energy savings, luminous efficacy and greater reliability, are becoming preferred over conventional white light sources. Currently, only light output depreciation is considered for life estimation of light emitting diode luminaires but it is recommended to include colour shift variations for applications demanding colour stability. In this paper, an extended Kalman filter is employed to determine L70 life and colour temperature degradation over life of a light emitting diode luminaire. The colour shift in terms of Duv is determined by statistical polynomial cure fitting. The variation in chromaticity coordinates over life is determined and life based on colour shift is determined by acceptable Duv limits. The results are compared to life determined by the IES-TM-21 method and the correlated colour temperature limits taken from the luminaire data sheet.

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Exposure to Salinity and Light Spectra Regulates Glucosinolates, Phenolics, and Antioxidant Capacity of Brassica carinata L. Microgreens

Antioxidants ◽

10.3390/antiox10081183 ◽

2021 ◽

Vol 10 (8) ◽

pp. 1183

Author(s):

Sylvia Maina ◽

Da Hye Ryu ◽

Jwa Yeong Cho ◽

Da Seul Jung ◽

Jai-Eok Park ◽

...

Keyword(s):

Oxidative Stress ◽

High Performance ◽

Antioxidant Activities ◽

Light Exposure ◽

Brassica Carinata ◽

Bioactive Metabolites ◽

Heme Oxygenase 1 ◽

Related Factor ◽

Light Emitting ◽

Flight Mass Spectrometry

The effect of salt treatment on Brassica carinata (BC) microgreens grown under different light wavelengths on glucosinolates (GLs) and phenolic compounds were evaluated. Quantifiable GLs were identified using ultra-high performance-quadrupole time of flight mass spectrometry. Extracts’ ability to activate antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT)) was evaluated on human colorectal carcinoma cells (HCT116). Furthermore, BC compounds’ ability to activate expression of nuclear transcription factor-erythroid 2 related factor (Nrf2) and heme-oxygenase-1 (HO-1) proteins was examined using specific antibodies on HCT116 cells. Sinigrin (SIN) was the abundant GLs of the six compounds identified and its content together with total aliphatic GLs increased in saline conditions. Fluorescent (FL) and blue plus red (B1R1) lights were identified as stable cultivation conditions for microgreens, promoting biomass and glucobrassicin contents, whereas other identified individual and total indole GLs behaved differently in saline and non-saline environments. Blue light-emitting diodes and FL light in saline treatments mostly enhanced SIN, phenolics and antioxidant activities. The increased SOD and CAT activities render the BC microgreens suitable for lowering oxidative stress. Additionally, activation of Nrf2, and HO-1 protein expression by the GLs rich extracts, demonstrate their potential to treat and prevent oxidative stress and inflammatory disorders. Therefore, effective salt treatments and light exposure to BC microgreens present an opportunity for targeted regulation of growth and accumulation of bioactive metabolites.

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Colourising daylight in buildings: Visual responses in a daylit room supplemented with colour-changing light-emitting diode luminaires

Indoor and Built Environment ◽

10.1177/1420326x16666387 ◽

2016 ◽

Vol 27 (1) ◽

pp. 34-46 ◽

Cited By ~ 3

Author(s):

Zhonghua Gou

Keyword(s):

Light Source ◽

Light Emitting Diode ◽

Green Light ◽

Natural Light ◽

Artificial Light ◽

Visual Responses ◽

Light Emitting ◽

Colour Temperature ◽

Negative Effect ◽

Changing Light

This research proposes the use of colour-changing light-emitting diode (LED) luminaires to supplement daylight for more sensory working or living environments. An experiment was conducted to examine a room lit by a mixture of natural light from window walls and artificial light from LED luminaires which could be programmed to produce four colour lights: orange (correlated colour temperature around 2000 K), yellow (around 3000 K), green (around 7000 K) and blue (around 8000 K). Participants were required to answer questions pertaining to function (naturalness of selected objects) and sensation (brightness, relaxation, pleasantness and interest). Generally, when daylight was mixed with warm colour, such as orange or yellow, the room was more interesting. Further comparison pointed out that the green light might have a negative effect for daylight perception. The most important finding is that when daylight was supplemented with the blue LED luminaires, the room was most relaxing, pleasing and natural, which was preferred by participants. The findings of this research would inform architects, designers to decide on how to use coloured luminaires as a supplementary light source for daylight to enhance sensory experience in buildings.

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High-Capacity, Fast-Response, and Photocapacitor-Based Terpolymer Phosphor Composite

Polymers ◽

10.3390/polym12020349 ◽

2020 ◽

Vol 12 (2) ◽

pp. 349 ◽

Cited By ~ 1

Author(s):

Marwa Mokni ◽

Francesco Pedroli ◽

Giulia D’Ambrogio ◽

Minh-Quyen Le ◽

Pierre-Jean Cottinet ◽

...

Keyword(s):

High Performance ◽

Vinylidene Fluoride ◽

Light Exposure ◽

High Capacity ◽

Green Light ◽

Material Design ◽

Fast Response ◽

Electrical Signal ◽

Light Sources ◽

Dielectric Characterization

This paper describes a new class of light transducer-based poly (vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) terpolymer doped with 50% wt. phosphor particles that enables to efficiently transform light energy into an electrical signal. Broadband dielectric characterization together with experimental results on photo-electric conversion demonstrated high capacitance variation of the proposed composite under light exposure, confirming promising potential of our sensor device for application in retinal prostheses where the converted electrical signal can affect the biological activity of the neuron system. In addition to the benefit of being light-weight, having ultra-flexibility, and used in a simple process, the proposed photodetector composite leads to fast response and high sensibility in terms of photoelectrical coupling where significant increases in capacitance change of 78% and 25% have been recorded under blue and green light sources, respectively. These results demonstrated high-performance material design where phosphor filler contributes to promote charge-discharge efficiency as well as reduced dielectric loss in P(VDF-TrFE-CTFE), which facilitate the composite for flexible light transducer applications, especially in the medical environment.

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An LED-based luminaire for badminton court illumination

Lighting Research and Technology ◽

10.1177/1477153515610800 ◽

2015 ◽

Vol 49 (3) ◽

pp. 396-406 ◽

Cited By ~ 3

Author(s):

X-H Lee ◽

J-T Yang ◽

J-H Chang ◽

W-T Chien ◽

Y-C Lo ◽

...

Keyword(s):

Computer Simulation ◽

Power Consumption ◽

Electric Power ◽

High Performance ◽

Light Emitting Diode ◽

Light Sources ◽

Volume Scattering ◽

Light Emitting ◽

Low Luminance ◽

Before And After

In this paper, the design of a luminaire for badminton court illumination is demonstrated from concept through computer simulation, construction trials, on-site installation, comparison with simulations and, finally, evaluations of the illuminated environment before and after the installation of the luminaires. The luminaire is composed of two high-performance light-emitting diode lighting modules, volume scattering diffusers with a one-shot transmittance higher than 70% and a reflecting cavity with a reflectivity higher than 85%. The luminaire has three different exit faces forming three Lambertian-like light sources with low luminance so as to reduce glare to the players when looking at the flight of the shuttlecock. Under similar total electric power consumption, compared to the original traditional lighting, the average illuminance on the ground is enhanced by about 300% and the uniformity is obviously improved. A questionnaire was issued to players before and after the installation of the new light-emitting diode luminaires. The new installation gained much more positive responses for brightness, comfort and number of usable courts from the players than the old installation.

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Characteristics of bilirubin photochemical changes under green light-emitting diodes in humans compared with animal species

Scientific Reports ◽

10.1038/s41598-021-85632-5 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kohichiroh Nii ◽

Hitoshi Okada ◽

Susumu Itoh ◽

Takashi Kusaka

Keyword(s):

Production Rate ◽

High Performance ◽

Time Course ◽

Light Emitting Diodes ◽

Green Light ◽

Light Sources ◽

Light Emitting ◽

Course Changes ◽

Complex Solutions ◽

Kinetics Of

AbstractPhototherapy using light-emitting diodes (LEDs) centered on the green spectrum, which has a high cyclobilirubin production rate, was as effective as that centered on the blue spectrum for neonatal hyperbilirubinemia. There are no reports of species differences in bilirubin photochemical changes in this spectrum, and the characteristics of bilirubin photochemical changes in humans must be elucidated to proceed with the development of new light sources that include these spectra. This report describes the characteristic photochemical kinetics of bilirubin under green-spectrum LEDs in human, rat, rabbit, dog, pig, sheep, bovine and chicken serum albumin and rhesus monkey serum. These albumin-bilirubin complex solutions were irradiated by green LEDs, and the time-course changes in bilirubin photoisomers were measured by high-performance liquid chromatography. The cyclobilirubin production rates in humans, pigs, and monkeys were significantly higher than those in other species. The rate constant of (EZ)-cyclobilirubin production from (EZ)-bilirubin ‘k’ was significantly higher in humans and monkeys than in other species. In conclusion, bilirubin photochemical kinetics under green spectrum LEDs in humans were characterized by a high cyclobilirubin production rate at a low substrate concentration. The bilirubin photochemical kinetics in monkeys were similar to those in humans.

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The State of Museum Lighting in Russia

Light & Engineering ◽

10.33383/2019-054 ◽

2020 ◽

pp. 38-46

Author(s):

Aleksandra A. Bartseva ◽

George V. Boos ◽

Anatoly Sh. Chernyak ◽

Alyona B. Kuznetsova ◽

Eugene I. Rozovsky

Keyword(s):

Russian Federation ◽

Light Emitting Diodes ◽

The State ◽

Light Sources ◽

Light Emitting ◽

Led Lighting ◽

Colour Temperature ◽

Luminance Distribution ◽

The Russian Federation ◽

Colour Rendering

The article contains the results of analysis of answers of 90 museums of the Russian Federation to questions regarding lighting of these museums as well as the results of inspection and measurement of lighting parameters (average exhibit illuminance, correlated colour temperature, colour rendering index, and luminance distribution) conducted in 7 museums and 1 conservation centre. It is found that museum lighting in the Russian Federation generally complies with the applicable requirements and recommendations and requires fundamental changes only in few cases. Many museums already use light emitting diodes (LEDs) as light sources and are ready to cross over to LED lighting completely. In the meantime, museums (primarily small ones) consider lack of regulations in the sphere of museum lighting one of the major problems.

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Gallium Nitride Metalens for Image Decryption

Crystals ◽

10.3390/cryst11111320 ◽

2021 ◽

Vol 11 (11) ◽

pp. 1320

Author(s):

Meng-Hsin Chen ◽

Jia-Ying Li ◽

Vin-Cent Su

Keyword(s):

Gallium Nitride ◽

Electromagnetic Waves ◽

High Performance ◽

Dielectric Material ◽

Rapid Development ◽

Incident Light ◽

Superposition Principle ◽

Digital Data ◽

Light Sources ◽

Light Emitting

As the demand for secure digital data continues to increase, image encryption and decryption have recently received tremendous attention. The rapid development of ultrathin metasurfaces has mainly been driven by the desire for the introduction of novel methods with which electromagnetic waves can be manipulated. As a promising application of metasurfaces, metalenses have shown great potential to replace bulky traditional optical devices. In this work, we present that the images produced by a commercially available projector are encrypted by using the color superposition principle, and the fabricated metalens is subsequently utilized to perform image decryption with an incidence made of white light-emitting diodes (LEDs). The correct positions for image decryption are carefully found by three distinct diode lasers as incident light sources. Recent investigations show that high-performance metalenses can be successfully developed once the suitable dielectric material is chosen. As a consequence, our metalens of high performance is composed of hexagon-resonated elements (HREs) made of gallium nitride (GaN) and is capable of resolving line width as small as 870 nm. The metalens with a smaller diameter of 8 μm is numerically simulated with a diffraction-limited focusing efficiency as high as 92%. This work once again shows that GaN metalenses, as future optics, have great prospects in expanding widespread applications in the near future.

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