Pupilmate: A do-it-yourself frugal pupilometer.

Melatonin counteracts oxidative damage in lens by regulation of Nrf2 and NLRP3 inflammasome activity

This study aims to analysis at the composition of fish catches and the fishing effectiveness of fixed lift nets fitted with LED lights of varying color combinations. This research was carried out from May to June 2019, located in the waters of Pangkajene Regency and the Islands. Two fixed lift nets units, 16 white light Emitting Diode (LED) lights and 16 pairs of white blue and yellow combination lights, Global Positioning System (GPS), Stop watch, Digital scale, Digital camera, Logbook, Meter, Current meter, Thermometer, Refractometer, and Lux meter. The research method used in this study is Experimental fishing in fixed lift nets fishing operations using LED lights. Experimental research of white and white combination LED light color (control), and blue, white and yellow LED light color (Treatment) used in 2 fixed lift nets. The fixed lift nets used is 15 meters long and 15 meters wide with a height of 25 meters from the seabed to the top pole with a building height of 10 meters above sea level. The data collection technique was carried out by following directly the catching operation of two fixed lift nets with different color combinations of lights. The data collected is the position of the fishing ground and catch data. Data analysis was carried out qualitatively and quantitatively. Qualitative analysis by looking at the technical aspects of operations on the fixed lift nets and data tabulation. Quantitative analysis was carried out using statistical methods and comparison of fish catches using two treatments using LED light colors. The results show that the composition of fish catches using color combinations (white, blue and yellow) shows higher yields when compared to white. The composition of the catch in the fixed lift nets is divided into three groups, namely the main catch (main catch), bycatch (bycatch) and discarded catch (discard). The use of a combination of LED lights on the fixed lift nets got a catch of 1,347.21 Kg, while the use of white LED lights got a catch of 906.21 Kg. The difference between the catches of the two treatments was 441 kg or 49% of the fish caught using white LEDs. From these results it can be concluded that the use of color combinations of LED lights is more effective than the use of white LED lights.

built environment the mixed blessing of Phosphor-based White leDs

The use of light-emitting diodes (LEDs) in vegetable species is one of the technological procedures applied to improve the spectral composition of light in protected areas, as well as to stimulate plant growth, obtaining high values of production and increasing resistance to conditions of culture. The biological material represented by tomato seedlings, from varieties with nutritional value and with high ecological plasticity, was studied in terms of characterizing the effects of applying the treatment using light fields emitted by blue, red and white LEDs, by analysis physiological parameters, such as: photosynthesis intensity (μmols CO2m-2s -1), transpiration intensity (mmoles H2O m-2s -1), stomatal conductance (mols H2O m-2s -1) and intercellular carbon dioxide (mmol CO2 mol-1 air). In this study, the estimation of the amount of total chlorophyll (mg m-2), was also investigated. The determinations of the physiological parameters were performed in 3 series, and the recorded results were statistically analysed, by expressing the significance of the differences between the control and the studied tomato varieties being studied. Thus, after the treatment period, applied in 23 days (Series II), with monochrome LEDs, at the level of the stomatal conductance parameter, statistically assured values were registered for the plants in the ‘L-75’ line exposed to White LED and for those in the ‘L-76’ line exposed to the Blue LED. The analysis of the results from the investigation of the physiological parameters at the level of the leaves from the experimental samples indicated that after 35 days (Series III), from the application of the treatments of 30 minutes/day, with White LED light, they ensured the plants tomatoes from the ‘L-76’ line, distinctly significantly positive values, compared to those of the control plants, at the intensity of photosynthesis and the internal concentration of CO2.

Simultaneous illumination and communication using solid-state lighting devices like white light-emitting diode (LED) light sources is gaining popularity. The white light LED comprises a single-colored yellow phosphor excited by the blue LED chip. Therefore, color-quality determining parameters like color-rendering index (CRI), correlated color temperature (CCT), and CIE 1931 chromaticity coordinates of generic white LED sources are poor. This article presents the development of multi-color phosphors excited by a blue LED to improve light quality and bandwidth. A multi-layer stacking of phosphor layers excited by a blue LED led to the quenching of photoluminescence (PL) and showed limited bandwidth. To solve this problem, a lens-free, electrically powered, broadband white light source is designed by mounting multi-color phosphor LEDs in a co-planar ring-topology. The CRI, CCT, and CIE 1931 chromaticity coordinates of the designed lamp (DL) were found to be 90, 5114 K, and (0.33, 0.33), respectively, which is a good quality lamp for indoor lighting. CRI of DL was found to be 16% better than that of white LED (WL). Assessment of visible light communications (VLC) feasibility using the DL includes time interval error (TIE) of data pattern or jitter analysis, eye diagram, signal-to-noise ratio (SNR), fast Fourier transform (FFT), and power spectral density (PSD). DL transmits binary data stream faster than WL due to a reduction in rise time and total jitter by 31% and 39%, respectively. The autocorrelation function displayed a narrow temporal pulse for DL. The DL is beneficial for providing high-quality illumination indoors while minimizing PL quenching. Additionally, it is suitable for indoor VLC applications.

Recognition of the extent and magnitude of night-time light pollution impacts on natural ecosystems is increasing, with pervasive effects observed in both nocturnal and diurnal species. Municipal and industrial lighting is on the cusp of a step change where energy-efficient lighting technology is driving a shift from “yellow” high-pressure sodium vapor lamps (HPS) to new “white” light-emitting diodes (LEDs). We hypothesized that white LEDs would be more attractive and thus have greater ecological impacts than HPS due to the peak UV-green-blue visual sensitivity of nocturnal invertebrates. Our results support this hypothesis; on average LED light traps captured 48% more insects than were captured with light traps fitted with HPS lamps, and this effect was dependent on air temperature (significant light × air temperature interaction). We found no evidence that manipulating the color temperature of white LEDs would minimize the ecological impacts of the adoption of white LED lights. As such, large-scale adoption of energy-efficient white LED lighting for municipal and industrial use may exacerbate ecological impacts and potentially amplify phytosanitary pest infestations. Our findings highlight the urgent need for collaborative research between ecologists and electrical engineers to ensure that future developments in LED technology minimize their potential ecological effects.

Soilless cultivation with artificial lighting has the potential to augment vegetable crop production, particularly lettuce, but yields are lower compared to natural sunlight, especially in monochromatic light technologies. Research suggests that color blending with light-emitting diodes (LEDs) can enhance production, yet many overlook the importance of nutrient management. The use of sulfur–silica fertilizer, known for enhancing plant growth in low-light stress conditions, supports this assertion. The study employed a randomized complete block design with two factors, each repeated four times. The treatments included three LED light colors: white LED (L1), blue LED (L2), and red LED (L3). Two fertilizer treatments were applied: absence of sulfur–silica fertilizer (P1) and presence of sulfur–silica fertilizer (P2). The study finds that optimal growth of lettuce plants is achieved through the utilization of both red and white LED lights, with red LED yielding the highest fresh leaf weight. The red LED treatments outperform other LED colors in terms of protein, carbohydrate, and total energy production. Introducing sulfur–silica fertilizer can promote superior lettuce growth, albeit at the cost of reduced fresh leaf weight. The application of sulfur–silica fertilizer leads to decreased protein and carbohydrate levels but enhances the overall energy content of the lettuce.

This paper demonstrates the strong enhancement of light extraction efficiency of light-emitting diodes (LEDs) by a novel three-dimensionally arranged micro-cavity. There are several optimal designed parameters, including chip dimensions, absorption coefficients, the shape of the micro-cavity and package are analyzed on the basis of a Monte-Carlo ray tracing simulation. The most important that studying includes GaN LEDs which are applied to various applications, including traffic signals, backlight system for LCD and outdoor illumination by white light LEDs. The functional of the three-dimensionally arranged micro-cavity is to make the light extraction from LED with high efficiency. The shape of micro-cavities are making like hexagon solids on the top view. The structure were evaluated and simulated by TracePro software respectively. The light extraction efficiency of LED can be greatly improved by three-dimensionally arranged micro-cavity. This study shows that the micro-cavities induced on the surface rather than that inside the LED greatly enhances the light extraction efficiency. This stipulation holds for both sapphire-based and Thin-GaN LEDs. The results indeed identify the attributes of the LED, which make it possible to achieve excellent luminance performance using a GaN-based approach from the LED of "three-dimensionally arranged micro-cavity". This structure was stringent expected to allow a high-efficiency LED, since the illumination systems needed for higher luminance energy can be added independently of the effects.

White-light phosphor-based light-emitting diode (LED) can be used to provide lighting and visible light communication (VLC) simultaneously. However, the long relaxation time of phosphor can reduce the modulation bandwidth and limit the VLC data rate. Recent VLC works focus on improving the LED modulation bandwidths. Here, we propose and demonstrate the use of adaptive Volterra filtering (AVF) to increase the data rate of a white-light LED VLC system. The detailed algorithm and implementation of the AVF for the VLC system have been discussed. Using our proposed electrical frontend circuit and the proposed AVF, a significant data rate enhancement to 700.68 Mbit/s is achieved after 1-m free-space transmission using a single white-light phosphor-based LED.

Cataract is the major cause for legal blindness in the world. Oxidative stress on the lens epithelial cells (hLECs) is the most important factor in cataract formation. Cumulative light-exposure from widely used light-emitting diodes (LEDs) may pose a potential oxidative threat to the lens epithelium, due to the high-energy blue light component in the white-light emission from diodes. In the interest of perfecting biosafety standards for LED domestic lighting, this study analyzed the photobiological effect of white LED light with different correlated color temperatures (CCTs) on cultured hLECs. The hLECs were cultured and cumulatively exposed to multichromatic white LED light with CCTs of 2954, 5624, and 7378 K. Cell viability of hLECs was measured by Cell Counting Kit-8 (CCK-8) assay. DNA damage was determined by alkaline comet assay. Intracellular reactive oxygen species (ROS) generation, cell cycle, and apoptosis were quantified by flow cytometry. Compared with 2954 and 5624 K LED light, LED light having a CCT of 7378 K caused overproduction of intracellular ROS and severe DNA damage, which triggered G2 /M arrest and apoptosis. These results indicate that white LEDs with a high CCT could cause significant photobiological damage to hLECs.

Visible light communications (VLC) use modern solid-state light-emitting diodes (LEDs) to broadcast information. Emerging white-light LEDs allow the combination of lighting and optical wireless communication in one optical source. In this paper, a new LED lighting design using one-chip-type white LEDs is proposed for efficient illumination and optical wireless communications under the existence of several obstacles. Lighting and communication performance are analyzed to show the effectiveness of the proposed LED lighting. Specifically, the signal-to-noise ratio considering intersymbol interference and the bit-error rate of variable pulse position modulation (VPPM) with dimming control are considered.

Improved thermal stability and quantum efficiency of novel cyan phosphors toward full-visible-spectrum lighting

ABSTRACTIn this article, a simple dynamic light controller (DLC) is proposed, designed, and fabricated for practical realization of variable correlated color temperature (CCT) but constant light output white light emitting diode (WLED) light source. This WLED light source consists of alternate strings of warm white (WW) and cool white (CW) LEDs. Light control logic of developed DLC is based on Grassman’s color mixing law and hence the range of CCT variation of the test light source lies within the CCT values of the WW and the CW LEDs. A pulse width modulation (PWM) technique is applied to implement the light control logic and embedded in a PIC microcontroller to control the light outputs of two WLED arrays through enhanced PWM mode with dual PWM output. The developed controller is connected with the test light source and controllable by infrared (IR) remote within a distance of 4 m. Thus, the developed DLC is an integrated module consisting of an IR receiver, IR decoder, control signal (PWM) generator, amplifier, and switching device. Performance of the developed DLC is experimentally validated for a set of desired CCT points (2840–5750 K) and constant illuminance (300 lx) measured at a fixed distance. Measured CCT values show maximum deviation of 160 and 194 K for warm white and cool white regions, respectively, compared to desired CCT points. On the other hand, the deviation of measured illuminance values lies within to with respect to set illuminance value of 300 lx. Variations of measured CCT lie within the acceptable range. Experimental results establish the satisfactory performance of the developed DLC.

Three different types of white light emitting diodes (LEDs) and three types of single color LEDs were tested as light sources for stroboscopic scanning white light interferometry (SSWLI) for dynamic (MEMS) characterization. Short, intense, light pulses and low duty cycle (< 10%) are required to freeze the motion of an oscillating sample. A custom designed LED driver was built utilizing a Metal-Core Printed Circuit Board. At the core of the circuit is a CMOS high speed high current gate driver (IXDD415SI). The LED pulser is compact (50×110 mm 2 ), has good thermal resistivity (0.45 °C/W), wide bandwidth (~DC-10 MHz), and can drive single LEDs at 5A peak current (0.7% duty cycle at 1 MHz). The shortest measured electrical pulses were 6.2 ± 0.1 ns FDHM. The minimum measured Full Duration at Half Maximum (FDHM) of the optical pulse was 8.4 ± 0.1 ns using nonphosphor white LED and 32.1 ± 0.1 ns using white phosphor-converted LED (0.7 % duty cycle at 1 MHz in both cases). The minimum optical pulse FDHM for a single color blue/green LED was 6.4 ± 0.1 ns. The maximum intensity of these pulses was 630 ± 40 μW and 540 ± 30 μW, respectively. All types of white LEDs could be used for stroboscopic SWLI measurements at frequencies up to 2 MHz. For higher frequencies, non-phosphor white LEDs must be used together with a cyan LED to avoid ringing in the SWLI interferogram.

Due to the various advantages on illumination, high-power light emitting diode (LED) system has been focused recently. Because the light source that consists of red, green and blue LEDs can provide full high definition color gamut with advantage of longer lifetime, LED light source starts to be applied in digital display system. However, much heat is dissipated from LED and operating temperature severely influences the characteristics of LEDs including dominant luminosity wavelength, luminosity and lifetime. Therefore careful thermal management is crucial to ensure accurate image quality of display device as well as guaranteed lifetime. The present study is conducted to investigate the performance of thermal management system for LED light source in rear projection TV. The result shows that the reducing thermal resistance between LEDs and substrate is the most effective way to dissipate heat and the applicable limit of thermal resistance is existed for various heat-dissipating conditions of LEDs. And it is also suggested that the efficacy of heat transport system from LED to ambient applied in red, green and blue LED light system to ensure the product quality