Wavelength LED Research Articles

Dual Wavelength LEDs Induce Reactive Oxygen Species and Nitric Oxide That Inhibit the Production of Dihydrotestosterone by 5-α Reductase.

Androgenetic alopecia (AGA) causes balding in approximately 50% of adults. One primary cause of AGA is synthesis of dihydrotestosterone from testosterone by 5-α reductase. Systemic pharmaceutical interventions have potentially serious side effects, necessitating development of localized interventions. One such approach is administration of red light via low level light therapy (LLLT), which has promising clinical data. However, the LLLT mechanism of action remains unclear. We investigated the ability of LLLT to stimulate nitric oxide (NO) and the role of NO in inhibition of DHT synthesis. Our results show that red and red-orange light induce NO release in a cell-free platform. In A549 and HEK293T cells, we demonstrate 620 and 660 nm LED-emitted light stimulates the production of NO, reactive oxygen species (ROS), and decreases DHT synthesis. These results provide a plausible mechanism of action for LLLT employing LED-emitted red and red-orange wavelengths of light to treat AGA.

Effect of different LED wavelength absorption spectra and light intensities on in vitro shoot proliferation of GF 677, MM 106 and Gisela 6 rootstocks

Effect of different LED wavelength absorption spectra and light intensities on in vitro shoot proliferation of GF 677, MM 106 and Gisela 6 rootstocks

Photoactive integrated microfluidic valves for on-chip fluid control

In microfluidics, on-chip fluid control is crucial for applications where programmable and automated fluid handling with low dead volume and limited auxiliary equipment is desired. This is, for instance, the case for point-of-care (POC) devices, especially in low resource settings. The integration of photoactive valves into a disposable microfluidic chip is one method of attaining low-power and non-contact fluid control in the blink of an LED. A liquid crystal network (LCN) based micro-valve was developed, which enables rapid fluid transfer on-chip by opening a venting channel upon illumination at 80 mW cm-2 with a 455 nm wavelength LED. We show in two proof-of-principle devices that multiple valves can be integrated into a 3D-printed microfluidic chip. Their individual actuation leads to directed sequential filling as well as draining of a reaction chamber, providing the prerequisite for intricate on-chip processes. Thus, our photoactive valves show the potential of facilitating programmable lab-on-a-chip experiments, for instance, for sample preparation such as for bind-wash-elute protocols, for immunoassay, or for amplification-based detection methods.

Photobiomodulation Mitigates PM2.5-Exacerbated Pathologies in a Mouse Model of Allergic Asthma.

Exposure to particulate matter (PM), especially PM2.5, is known to exacerbate asthma, posing a significant public health risk. This study investigated the asthma-reducing effects of photobiomodulation (PBM) in a mice model mimicking allergic airway inflammation exacerbated by PM2.5 exposure. The mice received sensitization with ovalbumin (OVA) and were subsequently treated with PM2.5 at a dose of 0.1 mg/kg every 3 days, for 9 times over 3 weeks during the challenge. PBM, using a 610 nm wavelength LED, was applied at 1.7 mW/cm2 to the respiratory tract via direct skin contact for 20 min daily for 19 days. Results showed that PBM significantly reduced airway hyperresponsiveness, plasma immunoglobulin E (IgE) and OVA-specific IgE, airway inflammation, T-helper type 2 cytokine, histamine and tryptase in bronchoalveolar lavage fluid (BALF), and goblet cell hyperplasia in PM2.5-exposed asthmatic mice. Moreover, PBM alleviated subepithelial fibrosis by reducing collagen deposition, airway smooth muscle mass, and expression of fibrosis-related genes. It mitigated reactive oxygen species generation, oxidative stress, endoplasmic reticulum stress, apoptotic cell death, ferroptosis, and modulated autophagic signals in the asthmatic mice exposed to PM2.5. These findings suggest that PBM could be a promising intervention for PM2.5-induced respiratory complications in patients with allergic asthma.

Compact three-dimensional fluorescence spectroscopy and its application in food safety

Three-Dimensional fluorescence spectroscopy is an indispensable tool for identification of substances by virtue of its ability to supply abundant characteristic information and high spectral resolution. In this work, we present a compact three-dimensional fluorescence spectrometer utilizing 18 different wavelength LEDs as excitation light source, instead of the conventional bulky multi-wavelength illumination strategy. This spectrometer can in situ obtain the spectral information accurately and fast, while reducing the weight and volume of system. To show its broad biochemical utility, we utilize the compact spectrometer to measure four types of vegetable oil samples from different origins, and analyzed their spectral characteristics. Moreover, we construct a deep learning model based on the 2D-CNN network to detect sesame oil adulteration qualitatively and quantitively. The Compact fluorescence spectrometer proposed has the potential to classify and grade food oils in situ, addressing the problem of sesame oil adulteration on the market.

Comparative study of composite single crystal and polycrystalline YAG:Ce phosphors for laser-based lighting applications

YAG:Ce, a widely employed phosphor for LED wavelength conversion applications, comes in different forms, including polycrystal (powder), single crystal, and composite single crystal varieties. We investigated Epoch NeoTM, a composite single crystal incorporating Al2O3 as a heat distribution and optical guiding material embedded within its luminescent core. The properties of Epoch Neo were analyzed and compared with those of its polycrystal counterparts in this paper. Multiple characterization techniques like chromaticity points, color temperature, phosphor temperature, and speckle pattern were employed to study the effect of variable laser input power on both polycrystal powder and composite single crystal of YAG:Ce. It was found that under the influence of pumping blue laser high input optical power the composite single crystal phosphor’s performance was significantly better compared to that of the polycrystal.

Effect of LED Wavelength and Power on the Hydroponic Indoor Vegetable Farming

Effect of LED Wavelength and Power on the Hydroponic Indoor Vegetable Farming

The photoinitiator of bifunctional α-hydroxy ketone with long-wavelength in photopolymerization under UV-LEDs

α-hydroxy ketone photoinitiators have been widely used in the photopolymerization industry, such as coating, ink and adhesive, for they have high initiating activity, good thermal stability, and yellowing resistance. However, few works have been reported in developing α-hydroxy ketone photoinitiators that match the absorption of long wavelength LEDs. In this work, a new bifunctional α-hydroxy ketone photoinitiator, (1,4-phenylene) bis (4-hydroxy-4-methylpent-1-en-3-one) (B-HMP), was synthesized and characterized. B-HMP exhibited excellent absorption among the wavelength of 300– 400 nm due to the introduction of unsaturated double bonds which could be employed to match 365/405 nm LEDs. From the results of electron spin resonance spin-trapping (EPR-ST) and steady-state photolysis investigations, the mechanism of the generation of radicals of B-HMP may be via not only the cleavage of CC bonds, but also intermolecular hydrogen abstraction. The efficiency of photopolymerization of B-HMP and triethanolamine (TEOA) was better than those of B-HMP alone because of the synergistic effect. Furthermore, the B-HMP/TEOA had a significantly yellowing resistance property.

Evaluating the phototactic behavior responses of the diamondback moth, Plutella xylostella, to some different wavelength LED lights in laboratory and field

Evaluating the phototactic behavior responses of the diamondback moth, Plutella xylostella, to some different wavelength LED lights in laboratory and field

Investigation on Optically Ultraviolet Response of Low-dimensional ZnO Structures Prepared by Chemical Processes

Chemical processes were used to synthesize ZnO low-dimensional structure including ZnO thin film ZnO nanorod and ZnO nanoparticle. ZnO thin film was prepared by sol-gel spin coating method while ZnO nanorod was prepared by hydrothermal process and ZnO nanoparticle was synthesized via co-precipitation route. The structural, morphological, optical and photoresponse properties were investigated by XRD, FESEM, UV-Visible spectrophotometer, I-V and I-t measurement. Comparison study on photoresponse properties of all structures was conducted under UV light with UV LED wavelength 375 nm. The UV photodetector based on ZnO nanoparticle sample showed superior photoresponse time to another ZnO low-dimensional structures. The results informed crucial factors including active surface area per volume, interaction in low-dimensional structures and specific properties in each structure playing key role on optical ultraviolet response.

Optical fluorescent sensor based on perovskite QDs for nitric oxide gas detection.

In this paper, a new, to the best of our knowledge, optical fluorescent sensor for the sensing of nitric oxide (NO) gas is developed. The optical NO sensor based on C s P b B r 3 perovskite quantum dots (PQDs) is coated on the surface of filter paper. The C s P b B r 3 PQD sensing material can be excited with a UV LED of a central wavelength at 380nm, and the optical sensor has been tested in regard to monitoring different NO concentrations from 0-1000ppm. The sensitivity of the optical NO sensor is represented in terms of the ratio I N2/I 1000p p m N O , where I N2 and I 1000p p m N O represent the detected fluorescence intensities in pure nitrogen and 1000ppm NO environments, respectively. The experimental results show that the optical NO sensor has a sensitivity of 6. In addition, the response time was 26s when switching from pure nitrogen to 1000ppm NO and 117s when switching from 1000ppm NO to pure nitrogen. Finally, the optical sensor may open a new approach for the sensing of the NO concentration in the harsh reacting environmental applications.

Effects of far infrared ray illumination on the performance, blood biochemistry, and faecal microflora of laying hens at different production stages

This study investigated the effect of far-infrared ray (FIR) illumination on performance, blood biochemistry, and faecal microflora of laying hens at different production stages. A total of 360 Hy-line brown laying hens were randomly allocated in a 2 × 2 factorial arrangement with six replicates. Hens were distributed in two production stages (30–39 and 45–54 weeks-old). Each group was exposed to two light types (light emitting diode; LED and LED+FIR) in separate rooms. The LED treatment illuminated a wavelength of 650 ± 10 nm (0.65 ± 0.01 μm), while LED+FIR treatment emitted 15 ± 10 μm with an LED wavelength. The results showed an interaction between egg production stages and light types on the serum triglyceride concentration. The hens exposed to the LED+FIR and LED treatments showed similar egg production, feed intake, egg weight, feed conversion ratio (FCR), as well as albumen height, haugh unit, and shell thickness of eggs. LED+FIR substantially decreased the concentration of serum cholesterol (CHOL), HDL cholesterol (HDLC), and triglyceride (TG) compared to LED lighting. LED+FIR substantially reduced the number of total microbes, Escherichia coli, and Salmonella in faeces compared to birds exposed to LED light. These findings suggest that LED+FIR lights may improve hen health and the hen house environment.

LED를 이용한 건강기기에 적용 가능한 LED 광원의 전력밀도 및 간섭에 대한 설계

This design is about low-energy optical therapy using the photo-chemical effect of light rays on the living body using RED LED and IR LED, and it is about the emisson wavelength and power density of LED. The amount of power in light transmitted to the body by 660nm red light and 830nm near-infrared light passing through the skin was simulated according to the skin depth and the absorption coefficient of fat. In addition, the power density for the interference effect between adjacent LED was calculated for the arrangement of LED. As for the power density according to the skin depth, it was confirmed that the power density at the abdominal depth of 3.5cm would supply about 0.44mW/㎠ of energy by adding the red light power density of 1.76mW/㎠ and the power density by the IR LED.

The optimization of culture conditions for the enhancement of biomass and lipids in Chlamydomonas hedleyi using a two-phase culture system

With the growing interest in biofuels, it is necessary to explore different species for the determination of the right candidates. The use of less popular microalgal species as a model in microalgal research is important for exploring the potential of new species. Chlamydomonas hedleyi is among the species with unexploited potential and determining the right culture conditions may serve as a prerequisite for subsequent research. In this study, 2-L flasks, and 14-L photobioreactors were used as culture apparatus. The optimal conditions for the accumulation of biomass and lipids in this species are 240 mg/L NaNO3, green LED wavelength as stress for lipid accumulation, red LED (625 nm) for biomass accumulation, 18:6-h light/dark cycle, 300 μmol/m2/s, the agitation speed of 200 rpm, the aeration rate of 1.00 and 0.75 vvm for biomass and lipid production respectively. The lipid content ranged from 24 to 60 % (w/w). The highest biomass produced was 1.45 g dcw/L.

Efficiency enhancement mechanism of piezoelectric effect in long wavelength InGaN-based LED.

Improving the luminescence efficiency of InGaN-based long wavelength LEDs for use in micro-LED full-colour displays remains a huge challenge. The strain-induced piezoelectric effect is an effective measure for modulating the carrier redistribution at the InGaN/GaN heterointerfaces. Our theoretical results reveal that the hole injection is significantly improved by the diminution of the valence band offset (VBO) of the InGaN/GaN heterointerfaces along the [0001] direction, and inversely, the VBO increases along the [0001] direction. The energy band structures showed that the tensile strain of the GaN film grown on a silicon (Si) substrate could weaken the internal electric field of the InGaN well layer leading to a flattening of the energy band, which increases the overlap of electron and hole wave functions. In addition, the strain-induced piezoelectric polarisation of the InGaN layer on the Si substrate generates opposite sheet-bound charges at the heterointerfaces, which causes a reduction in the depletion region of the InGaN/GaN quantum wells (QWs). A systematic analysis illustrates that the control of the piezoelectric polarisation of the InGaN QW layer is available improve the internal quantum efficiency of the InGaN-based LEDs.

Использование светодиодов синего цвета на промысле гидробионтов в целях повышения эффективности промысла

The article highlights the development of the complex research on using blue spectrum LEDs, taking into account the literature data and the authors' own research. Reaction to light is shown related to stimulating the food activity of aquatic organisms. This is a complex of factors that determine the behavior of aquatic organisms moving towards a light source. Light in the blue segment of spectrum travels the longest distances from the source, so animals and plants have evolved to respond more to the light in this segment. Therefore, using blue LEDs stimu-lates the entire trophic food chain: phytoplankton (phytoplankton growth due to the effective absorption of light energy by chlorophylls a, b and carotenoids in this spectrum) → zooplankton (attracted to the blue light segment due to the reflex about the food presence) → hydrobionts eating zooplankton (attracted to the blue light segment because of the food reflex) → predatory aquatic organisms (also attracted to the blue light segment due to the food reflex). There has been proposed a method of choosing the LED wavelength to optimize the light source subject to the spectral sensitivity of photoreceptors, increasing the LED life with a decreased current, which helps improve the autonomous source life. Based on the nature-like approach and the choice of the light spectrum, using blue LEDs is found reasonable for fishing traditional light-fishing commercial species (saury and squid), as well as other hydrobionts that haven’t been caught using light before (crab, flounder and smelt). This approach allows to use light for catching other aquatic organisms not previously harvested by using light, as well as optimize light sources in fishing traditional commercial species (kilka).

Effects of different LED wavelength absorption spectra on in vitro shoot proliferation, leaf anatomy, photosynthetic pigments and photosystem II photochemistry of ‘GF677’ rootstock

ISHS X International Peach Symposium Effects of different LED wavelength absorption spectra on in vitro shoot proliferation, leaf anatomy, photosynthetic pigments and photosystem II photochemistry of ‘GF677’ rootstock

Safer school with near-UVA technology: novel applications for Environmental Hygiene

Abstract Background Schools are crowded places where outbreaks can occur. Systems capable of disinfecting air and surfaces could reduce the risk of transmission of infectious diseases. Aim to evaluate the effectiveness of a near-UVA (nUVA) LED ceiling lamp in improving environmental hygiene. Methods This cross-sectional study was conducted for 2 weeks between November and December 2020 in a kindergarten in Siena, Italy. Four ceiling lamps with LED wavelength of 405 nm were mounted on the room ceiling. The distance of the lamps from the floor was 2.70 m and 2.0 m from the desks. We preliminary selected 12 points in different sites of the room by measuring their irradiance values. We randomly sampled between 8 and 12 pairs of Petri Dishes (PD) daily during the study, incubated at 22 and 36C°, at different irradiation times: 8, 12 or 36 hours. Paired controls were used before using the lamps (at time T0), which were automatically switched ON overnight and compared with treatment (at time T1). Air sampling was also performed at T0 and T1. Statistical analysis was performed with Stata 14. Significance was set at 95% (p < 0.05). Results 520 PDs were used in the study: 130 PDs at T0 matched at T1 incubated at 36 °C and as many at 22 °C. The mean level of contamination at T0 was respectively 249 CFU (95 % CI 193.1 - 305.0) at 36 °C and 535.2 CFU (374.3 - 696.1) at 22 °C. The reduction was significant (p < 0.05) at T1: we had 87.4 CFU (56.3 - 118.6), equal to 65%, at 36C° and 149.6 CFU (83.7 - 215.4), equal to 72%, at 22C°. Different values were recorded stratifying for dose (irradiance per exposition time). A significant mean percentage reduction of air contamination was 95.3% (98.4 - 92.3). Conclusions The system was able to improve the environmental hygiene of the kindergarten. The advantage of using this technology in the presence of people is very important in the context of controlling environmental contamination. Key messages • Near-UVA are efficient in reducing the contamination level significantly in a real-life context, on the surfaces and of the air. • Crowded places favour germ outbreaks. Hygiene control is essential to reduce the risk of transmission of infectious diseases.

PiRamid: A compact Raspberry Pi imaging box to automate small-scale time-lapse digital analysis, suitable for laboratory and field use

Digital imaging permits the quantitation of many experiments, such as microbiological growth assays, but laboratory digital imaging systems can be expensive and too specialised. The Raspberry Pi camera platform makes automated, controlled imaging affordable with accessible customisation. When combined with open source software and open-source 3D printed hardware, the control over image quality and capture of this platform permits the rapid development of novel instrumentation. Here we present “PiRamid”, a compact, portable, and inexpensive enclosure for autonomous imaging both in the laboratory and in the field. The modular three-piece 3D printed design makes it easy to incorporate different camera systems or lighting configurations (e.g., single wavelength LED for fluorescence). The enclosed design allows complete control of illumination unlike a conventional digital camera or smartphone, on a tripod or handheld, under ambient lighting. The stackable design permits rapid sample addition or camera focus adjustment, with a corresponding change in magnification and resolution. The entire unit is small enough to fit within a microbiological incubator, and cheap enough (∼£100) to scale out for larger parallel experiments. Simply, Python scripts fully automate illumination and image capture for small-scale experiments with an ∼110×85 mm area at 70–90 µm resolution. We demonstrate the versatility of PiRamid by capturing time-resolved, quantitative image data for a wide range of assays. Bacterial growth kinetics was captured for conventional microbiology (agar Petri dishes), 3D printed custom microbiology labware and microfluidic microbiology. To illustrate application beyond microbiology, we demonstrate time-lapse imaging of crystal growth and degradation of salad leaves. Minor modifications permit epi-illumination by addition of a LED ring to the camera module. We conclude that PiRamid permits inexpensive digital capture and quantitation of a wide range of experiments by time-lapse imaging to simplify both laboratory and field imaging.

Enhanced semiconductor nanowires improve safety of deep ultraviolet light emitters

Tunnel junctions and polarization doping may overcome challenges with short wavelength LEDs.