White Lamps Research Articles

Dye-Sensitized Solar Cells Characterization of Kitolod Leaves (Hippobroma longifora)

Energy from fossil fuels is decreasing day by day and also causes many environmental problems. In the current era, many environmentally friendly renewable energy sources have been developed, such as the development of DSSC (Dye Sensitized Solar Cells). DSSC is a technology that utilizes colored materials sourced from nature which are used as absorbers of sunlight energy to be converted into electrical energy. In this research, the synthesis and characterization of organic material from kitolod leaves as DSSC will be carried out. Kitolod leaves (Hippobroma longifora) are wild plants that usually grow in home gardens and rice fields. Kitolod leaves which have chlorophyll can support the absorption of sunlight if applied as a sensitizer in DSSC. The methods that will be used in this research are making TiO2 paste, dye solution preparation, electrolyte solution preparation, DSSC fabrication, testing and characterization. The tests that will be carried out are testing the TiO2 layer, dye absorption, and electric current. Meanwhile, the characterization that will be carried out is dye absorption using UV-Vis, and electric current using a potentiometer. From the results of light absorption shows that when the wavelength is 500 nm or the green light spectrum, the maximum light absorption by the chlorophyll of kitolod leaves is 1.78 (a.u.). The maximum voltage (Vm) and maximum current (Im) in daylight lamps have greater values ​​compared to warm white lamps. The highest efficiency of the solar light source is shown when the air mass is 1.5 (08.30-08.40). The time of DSSC immersion in dye also influences the resulting of Vm and Im values ​​which can be shown in that the Vm and Im values ​​of DSSC 2 (30 minutes) are greater than those of DSSC 1 (10 minutes). The results of open circuit voltage (Voc) and the short circuit current (Isc) in this research still need to be improved to produce better efficiency.

National Park visitors perceive benefits for themselves and wildlife under blended red-white outdoor lighting

Visitors to Colter Bay Village in Grand Teton National Park were surveyed to elicit their evaluations of experimental outdoor lighting conditions. Luminaires capable of dimming and switching between two LED modules (white, blended red-white) were installed in street and parking areas. The blended red-white lamps consisted of 30 narrowband LED with a peak wavelength 623 nm and two 3000 K white LEDs. Similar “red” lamps were previously shown to reduce impacts to bats and insects. The white and red lamps were closely matched for luminance. Measured horizontal illuminance at survey locations had an interquartile range from 0.63 to 3.82 lx. The red lamps produced lower perceived brightness (VB2(λ)), even after reflection off asphalt, yet survey participants expressed higher ratings for visual comfort and safety under red lighting. Surveys conducted earlier in the evening, with higher levels of predicted solar and measured horizontal illuminance, rated higher on visual comfort and safety, though these correlations were not as strong as the effect of lamp color. Streetlight ratings and support for lighting that protected natural resources were not contingent upon age or gender. Survey participants assessed red lighting as more protective of the environment. These results demonstrate that outdoor lighting designed to reduce ecological impacts can yield superior nocturnal experience for pedestrians.

Novel Tm3+/Dy3+ co-doped CaMoO4 transparent glass-ceramic phosphor for white LED applications

To develop new inorganic luminescent materials, a set of Dy3+/Tm3+ co-doped molybdate precursor glasses (PGs) were manufactured using the conventional melting method, and a novel CaMoO4 transparent fluorescent glass-ceramic (GC700-2 h) was achieved via controlled crystallization of PG at 700 ℃ for 2 h. The luminescent color of the glass phosphor was facilely modulated by varying the doping levels of Dy3+ and Tm3+. The glass phosphor with optimal doping concentration of 0.6Dy3+ and 0.6Tm3+ exhibits a color coordinate of (0.3334, 0.3107). Compared with PG, the luminous intensity and quantum yield of GC700-2 h sample is obviously increased, and GC720-2 h sample displays the color coordinate (0.3292, 0.2852), belonging to the standard white light region. Moreover, GC720-2 h sample possesses good thermal stability in fluorescence property. The white LED lamp encapsulated with GC720-2 h exhibits color temperature of 7564 K and color rendering index of 75.3. These results clearly show that the 0.6Dy3+/0.6Tm3+ co-doped glass and CaMoO4 glass-ceramic could be used as potential candidate material in the field of white light-emitting diodes.

Assessing the impact of temperature, pH, light and chemical oxidation on fucoxanthin colour changes, antioxidant activity and the resulting metabolites.

The present study evaluated the effects of temperature, pH, light and chemical oxidation on fucoxanthin changes in terms of colour, antioxidant activity and metabolomic profile. Additionally, the correlation between antioxidant activity and identified metabolites was analysed. It was found that colour change was significantly reduced at elevated heat (100 °C, *∆E = 0.81 ± 0.05), reduced pH (pH 3, *∆E = 0.59 ± 0.04) and length of light exposure (*∆E = 3.16 ± 0.04). Antioxidant activity decreased under all treatments. Among the temperatures tested, fucoxanthin exhibited the highest activity at 60 °C, ranging from 0.92 to 3.04 mg Trolox equivalents (TE) g-1. Significant activity reductions (P < 0.05) were observed as a result of pH changes in the 2,2-diphenyl-1-picrylhydrazyl and β-carotene bleaching assays. Exposure to light 2: warm white lamp for 120 h significantly reduced antioxidant activity (0.01 to 1.70 mg TE g-1). Chemical oxidation also led to reduced activity, ranging from 0.18 to 0.29 mg TE g-1. Multivariate data analysis revealed distinct profiles for temperature, pH, light and chemical oxidation treatments. Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics analysis identified 10 metabolites, and significant correlations (P < 0.05) indicate that these metabolites contributed to the samples' antioxidant activities. In conclusion, fucoxanthin tolerates well at 60 °C, within pH range 3-9, and within 8 h of light exposure, as indicated by its consistent antioxidant activity and minimal colour change. Each treatment resulted in distinct metabolite concentrations, as shown by LC-MS/MS-based metabolomics analysis. Further research into these metabolites could advance the understanding of their roles and aid in optimising processing conditions to favour beneficial metabolites. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Removal of Nitrogen and Phosphorus in Low Polluted Wastewater by Aquatic Plants: Impact of Monochromatic Light Radiation

Plant absorption via aquatic plants is vital for the deep purification of treated wastewater. This study aimed to determine the removal efficiencies of nitrogen and phosphorus for different aquatic plants and the effect of monochromatic light as compared to white light. Five plants (i.e., Iris pseudacorus, Oenanthe javanica, Zantedeschia aethiopica, Ipomoea aquatica Forssk. and Sagittaria trifolia) were cultured in prepared wastewater and radiated by white, red, green and blue LED lamps with 8 h radiation per day, respectively. After 4 d of cultivation, the O. javanica and S. trifolia exhibited relatively better growth status and higher TP removal rates (90%). The blue light radiation played a key role in the TP uptake of the tested plants. The N removal rates of plants were relatively lower (10–40%), limited by the low COD content. The S. trifolia exhibited the highest efficiency, and red light promoted the removal of TN and NO3−-N, whereas NH4+-N removal was driven by blue light radiation. So, O. javanica and S. trifolia coupled with blue and red lamps as supplementary light were suggested for the deep purification of municipal treated wastewater. The effect of intensity and ratio of monochromatic lights could be a direction for further research.

Photobiocidal Activity of TiO2/UHMWPE Composite Activated by Reduced Graphene Oxide under White Light.

Herein, we introduce a photobiocidal surface activated by white light. The photobiocidal surface was produced through thermocompressing a mixture of titanium dioxide (TiO2), ultra-high-molecular-weight polyethylene (UHMWPE), and reduced graphene oxide (rGO) powders. A photobiocidal activity was not observed on UHMWPE-TiO2. However, UHMWPE-TiO2@rGO exhibited potent photobiocidal activity (>3-log reduction) against Staphylococcus epidermidis and Escherichia coli bacteria after a 12 h exposure to white light. The activity was even more potent against the phage phi 6 virus, a SARS-CoV-2 surrogate, with a >5-log reduction after 6 h exposure to white light. Our mechanistic studies showed that the UHMWPE-TiO2@rGO was activated only by UV light, which accounts for 0.31% of the light emitted by the white LED lamp, producing reactive oxygen species that are lethal to microbes. This indicates that adding rGO to UHMWPE-TiO2 triggered intense photobiocidal activity even at shallow UV flux levels.

Innovative Stacked Yellow and Blue Mini-LED Chip for White Lamp Applications.

This study introduces a novel approach for fabricating vertically stacked mini-LED arrays, integrating InGaN yellow and blue epitaxial layers with a stress buffer layer to enhance optoelectronic characteristics and structural stability. This method significantly simplifies the LED design by reducing the need for RGB configurations, thus lowering costs and system complexity. Employing vertical stacking integration technology, the design achieves high-density, efficient white light production suitable for multifunctional applications, including automotive lighting and outdoor signage. Experimental results demonstrate the exceptional performance of the stacked yellow and blue mini-LEDs in terms of luminous efficiency, wavelength precision, and thermal stability. The study also explores the performance of these LEDs under varying temperature conditions and their long-term reliability, indicating that InGaN-based yellow LEDs offer superior performance over traditional AlGaInP yellow LEDs, particularly in high-temperature environments. This technology promises significant advancements in the design and application of lighting systems, with potential implications for both automotive and general illumination markets.

Two-dimensional Keitz method for the radiant power measurement of planar ultraviolet excilamps

Planar XeBr∗ and XeCl∗ excilamps emitting noncoherent narrowband UVB light (280–315 nm) are now widely used to cure psoriasis and vitiligo as well as to improve vitamin D synthesis. The two-dimensional integral formula has been deducted in this study, which is a good method and has great practical significance to calculate the total radiant power and assess the energy efficiency of a planar UV lamp. The measured radiant power of planar white LED lamps through a two-dimensional Keitz formula has been compared to that of gonio-photometer, verifying the applicability of the formula. The optimum measurement distance is dependent on the lamp length (1.5L≤D≤3.5L) for which the derivation from the two methods can be controlled within 10%. The planar XeBr∗ excilamps have been measured and compared to coaxial excilamps, which show similar patterns of change for the radiant characteristics. Since the planar radiant power formula only needs to measure normal illuminance at a certain distance from the symmetric center of the lamp, it is more convenient to use and is a low-cost method to promote the development of large-sized planar ultraviolet lamps.

How different daily light integrals and spectral treatments influence the development of Valerianella locusta plants grown in an indoor vertical farm

Light plays a crucial role in the development and growth rate of crops by impacting their physiology, morphology as well as the electricity cost for the system's operation which can significantly jeopardize the viability of a commercial-scale system. Different crops have different lighting demands in terms of quality (spectrum), quantity (intensity) and duration (photoperiod). At the same time only a little information is available in the literature concerning the minimum lighting requirements for indoor horticulture. This research aims to define the optimal combination of photoperiod, photosynthetically photon flux density (PPFD) and spectrum for indoor cultivation of Valerianella locusta plants by linking light and energy use efficiency to physiological responses of chlorophyll content and biomass production under different daily light integrals (DLI). Plants were cultivated in two growing towers with three layers of cultivation area under white LED lamps (WHITE) and two identical growing towers with three layers of cultivation area under blue/green/red/far-red lamps (BGRFR). The experimental setup is comprised of three different photoperiods (16, 14, 12 h · d−1) and three different PPFD (150, 250 and 350 μmol/m2s1), resulting in five daily light integrals (8.6, 10.8, 12.6, 14.4, 20.2 mol· m−2 · d−1). All growing towers and layers were equipped with a close-loop Ebb & Flow hydroponic system. Based on data analysis, spectra selection seems to have a significant impact on chlorophyll content, while lower DLIs did not correlate with lower chlorophyll content. The chlorophyll content was found to be similar either the plants received longer daily light hours or/and higher light intensity. Additionally, plants that grew under DLI 10.8 and 12.6 mol/m2d1 resulted in significantly higher fresh and dry biomass while at the same time required significantly lower electricity requirements due to the reduced hours of artificial lighting (14 and 12 h· d−1 respectively). Accordingly, light operation for Valerianella locusta plants under PPFD of 250 μmol/m2s1, 14 h of photoperiod and BGRFR spectra selection could be characterized as optimal for indoor cultivation to optimize the use of resources and ensure high-yield production, considering the specific setup of the cultivation system.

High‐Bandgap Perovskites for Efficient Indoor Light Harvesting

The use of metal‐halide perovskites in photovoltaic applications has become increasingly attractive due to their low‐temperature manufacturing processes and long charge‐carrier lifetimes. High‐bandgap perovskite solar cells have potential for indoor applications due to their efficient absorption of the spectrum of light‐emitting diodes (LEDs). This study investigates the performance of high‐bandgap perovskite solar cells under a wide range of lighting conditions, including a commercially available white LED lamp with a 5–40 000 lx illuminance range and a standard 1 sun reference. The performance of CH3NH3PbI3‐based perovskite solar cells to CH3NH3Pb(I0.8,Br0.2)3 solar cells with varying electron transport layers (ETL), including PCBM, PCBM:CMC, and CMC:ICBA fullerene combinations, is compared. Because the spectral response of perovskite solar cells covers the white LED spectrum very well, the major performance difference is related to the open‐circuit voltage and fill factor. The cells with the CH3NH3Pb(I0.8,Br0.2)3 absorber layer and the CMC:ICBA ETL demonstrate superior open‐circuit voltage and therefore a high efficiency above 29% at 200–500 lx, typical for indoor lighting.

Frequency Reconfigurable Antenna Design and Analysis with White LED Lamp, Red and Infra-red LEDs

Frequency Reconfigurable Antenna Design and Analysis with White LED Lamp, Red and Infra-red LEDs

The Effect of Lu3+ Doping on the Structural Stability and Luminescence Performances of Gd3Al5O12:Dy Phosphors

Transparent ceramics (Gd0.975−xLuxDy0.025)3Al5O12 (x = 0.2, 0.5, 0.975) are fabricated by vacuum sintering with the transmittance of ~60% at 583 nm. The doping of Lu3+ was beneficial to stabilize the garnet phase, and the best doping concentration was 20 at.%. All three (Gd, Lu)3Al5O12:Dy ceramics display typical Dy3+ emission, originating from 4F9/2 → 6HJ (J = 15/2, 13/2, 11/2) transition. Temperature-dependent luminescence spectra from 303.15 K to 603.15 K prove that the (Gd, Lu)3Al5O12:Dy ceramics had good thermal stability and could be an ideal yellow-emitting candidate in light-emitting diodes. The luminous efficiency of the encapsulated white LED lamp was found to be ~87.9 lm/W when the injection current was 600 mA. The transparent (Gd, Lu)3Al5O12:Dy ceramics show great application potential in various optical systems especially in the fields of luminescence and display.

Low-cost measurements of the ‘resonant’ wavelengths reflected by a compact disc under skimming light rays

We demonstrate the construction and utilization of an affordable apparatus using readily available materials to accurately measure in a quantitative manner the wavelengths reflected by a compact disc (CD) under skimming light rays. In fact, only a limited number of wavelengths can be revealed when light rays from a white lamp are directed at a CD (or a DVD) in a manner that specifically selects the rays that graze the surface of the horizontally held disc. We compare the results with the ones obtained with a commercial spectrometer, finding that they are in good agreement among them and with the theoretical predictions.

Light pre-conditioning at the seedling stage affected root growth behavior and enhanced the thermotolerance of Petunia × hybrida

An investigation studied the impact of spectral composition on plant responses to heat stress. Petunia × hybrida seedlings were grown under nine different light qualities, including the modifying and constant compositions of blue and red LEDs light, as well as Fluorescent and white LED lamps. After 28 days, the seedlings were exposed to hyperthermia (40 °C / 35 °C, 4 days). The results showed that the highest survival rate (100 %), and the lowest leaf chlorotic area (14 %) were observed among seedlings grown under modifying spectral compositions with a gradual increase in red light, which also showed the highest change rate of increased Chl a/ b ratio (262 %) and lowest change rate of increased total Chl/ Car ratio (45 %). Furthermore, seedlings grown under a gradual increase in red light showed the highest relative water content (82 %) and the lowest change rate of root water content (1.2 %). Moreover, the highest proline and lignin contents, along with the lowest electrolyte leakage, 7.22 µg g−1 FW, 104 mg g−1 FW, and 25 %, respectively, were observed in seedlings exposed to a gradual increase in red light after heat stress compared to other lighting treatments. Also, after heat stress, seedlings grown under a gradual increase in red light showed the highest contents of studied enzymatic antioxidants. Our investigation highlighted a link between spectral composition during the seedling stage and heat stress tolerance of examined plants. This method can potentially prepare plant material during the propagation stage against extreme temperatures.

Keanekaragaman Serangga Nokturnal Berdasarkan Warna Lampu Perangkap Cahaya di Balai Penelitian Tanaman Sayuran Desa Tongkoh Sumatera Utara

&#x0D; &#x0D; &#x0D; &#x0D; Nocturnal insects are a type of insect that is active at night and plays a role in maintaining the balance of the ecosystem and has an ecologically and economically occurring role. This study was conducted to determine the diversity, evenness, and dominance of nocturnal insects based on the color of the light trap lamp at the Vegetable Crop Research Center of Tongkoh Village, Karo Regency, North Sumatra. This study used the light trap method by making a transect 100 m long and on the transect, 5 observation stations were installed. There are 27 insect families consisting of 35 types of nocturnal insects with a total of 240 individuals. The most common type of insect found is Empoasca fabae. The diversity index (H') is included in the moderate category with a value of 2.10 on the green lamp trap, 1.38 on the blue lamp trap, 2.23 on the yellow lamp trap, 2.76 on the white lamp trap, and 2.26 on the red lamp trap, this shows that the insect diversity at the study site is in a stable condition. The dominance index (C) is categorized as low with a value of 0.184 on green light traps, 0.347 on blue lamp traps, 0.222 on yellow light traps, 0.092 on white light traps, and 0.150 on red light traps. This situation occurs because there is no type of nocturnal insect that is too dominant so that the diversity of insects is classified as being in a stable state.&#x0D; &#x0D; &#x0D; &#x0D; &#x0D;

Photo-Fenton degradation of tetracycline antibiotic over MIL-101(Cr)/FeOOH nanocomposite as stable and efficient visible light responsive photocatalyst.

Designing an inexpensive, easily synthesized, stable and efficient photocatalyst is a major challenge in photocatalysis area, especially when photo-reaction is performed in aquatic medium to degrade organic pollutants. To this aim, nano-sized MIL-101(Cr) (MIL = Materials Institute Lavoisier), as chemically tolerant metal-organic framework (MOF), was simply prepared via HF-free hydrothermal synthesis procedure. In order to decorate amorphous FeOOH quantum dots (QDs) on the surface of this MOF, various amounts of FeOOH QDs (i.e., 5, 10, 15 and 20 wt%) were synthesized in the presence of MIL-101(Cr) to prepare MIL-101(Cr)/FeOOH(x%) nanocomposites. Decoration of such iron oxide quantum dots on the surface of MIL-101(Cr) and investigation of its activity in photo-Fenton degradation of tetracycline (TC) antibiotic is reported here for the first time. Among the synthesized nanocomposites, MIL-101(Cr)/FeOOH(15%) demonstrated superior photo-Fenton activity in degradation of TC (80%) at short reaction time under optimum reaction condition using the energy-efficient white LED lamps as visible light source. It was observed that the synergy between any component of this photo-Fenton system such as nanocomposite, hydrogen peroxide and visible light is the main reason for enhancement of TC removal over time. Also, neither MIL-101(Cr) nor FeOOH QDs exhibited poor degradation efficiency, which implies the positive role of the coupling of these materials. Furthermore, the stability and recoverability of MIL-101(Cr)/FeOOH(15%) nanocomposite was investigated in four photo-Fenton cycles, which no significant decrease in TC degradation performance was observed.

Synthesis and photoluminescence properties of Ce3+ and Tb3+ doped Na3Gd(PO4)2 phosphors for white LEDs

Na3Gd(PO4)2 phosphors doped with rare-earth metal ions Ce3+ and Tb3+ were fabricated by the solid-state reaction method. Under the excitation of 340 nm light, the Ce3+-doped Na3Gd(PO4)2 phosphors exhibit a broad emission band ranging from 370 nm to 480 nm, which emitted blue light centered at 405 nm. When excited at 373 nm, the Tb3+-doped Na3Gd(PO4)2 phosphors presented a green light emission, including a strong peak located at 547 nm. In addition, both of the Na3Gd(PO4)2: Ce3+ and Na3Gd(PO4)2: Tb3+ phosphors showed excellent thermal stability at different temperatures, be specific in the Na3Gd(PO4)2: Ce3+ emission intensities at 150 °C could maintain about 84 % and the Na3Gd(PO4)2: Tb3+ could maintain about 92.9 % of those at room temperature. A prototype of the white light-emitting diodes lamp exhibiting bright white light was fabricated by using a 365 nm near-ultraviolet-emitting LED chip, combined with Na3Gd(PO4)2: Ce3+ blue phosphors, Na3Gd(PO4)2: Tb3+ green phosphors, and Na3Gd(PO4)2: Eu3+ red phosphors, which produced a high color rendering index of 89.4, and a relatively low correlated color temperature of 5496 K. Moreover, the CIE point was calculated to be at (0.3332, 0.3438), locating in the white light region. These results indicate that the as-prepared phosphors can be considered as potential candidates for ultraviolet/near-ultraviolet light-excited white light-emitting diodes applications.

Reconstruction of spectral irradiance in a real application with a multi-channel spectral sensor using convolutional neural networks.

Lighting is not only a key mediator for the perception of the architectural space but also plays a crucial role regarding the long-term well-being of its human occupants. Future lighting solutions must therefore be capable of monitoring lighting parameters to allow for a dynamic compensation of temporal changes from the optimal or intended conditions. Although mostly based on synthetic data, previous studies adopting small, low-cost, multi-band color sensors for this kind of parameter estimation have reported some promising preliminary results. Building up on these findings, the present work introduces a new methodology for estimating the absolute spectral irradiances of real-world lighting scenarios from the responses of a 10-channel spectral sensor by using a convolutional neural network approach. The lighting scenarios considered here are based on a tunable white floor lamp system set up at three different indoor locations and comprise combinations of LED, fluorescent, tungsten, and daylight lighting conditions. For white light mixtures of the various spectral components, the proposed reconstruction methodology yields estimates of the spectral power distribution with an average root-mean-square error of 1.6%, an average Δu'v' of less than 0.001, and an average illuminance accuracy of 2.7%. Sensor metamerism is discussed as a limiting factor for the achievable spectral reconstruction accuracy with certain light mixtures.

Extension of the working time of dental composites due to a new type of white operating lamp.

Dental composite materials for filling teeth are usually hardened by polymerisation lamps emitting blue light. However, the same wavelength is also emitted by light of dental operating lamps for lighting the oral cavity. Thus, the hardening of the composite is already initiated earlier, shortening the time of formability. The objective of this study is to develop a specific white LED for dental operating lamps. When restoring teeth, it enables dentists to work longer on light-curing composites in the same brightness. Based on a short-wave blue coloured LED and a fluorescent substance, a white luminescent LED with a colour temperature of approx. 3,000 K is produced as a prototype. The formable working times of three composites are measured for this LED and two dental head lamps at an illuminance of 10,000lx. Shorter working times of 98-237 s were measured for the headlamps and 409-807 s for the new LED. This light of the new LED is perceived by the human eye as warm white. The new LED extends the working time by the factor of 3.0 to 5.8 compared to the head lamps. This enables more precise modelling of fillings.

Using phosphor ZnB2O4:Mn2+ for enhancing the illuminating beam and hue standard in white light-emitting diodes

The enhancement in hue uniformity and luminous production of multiple-chip white LED lamps (MCW-LEDs) using dual-layer remote phosphor packaging designs are the emphases of this paper. We blended Mn 2+ activated strontium–barium silicate (ZnB 2 O 4 :Mn 2+ ) with the phosphor mixture and manage to record significant impacts of this new phosphor mixture on the LED lights’ lighting performance. There is evidence that the growing concentration of yellow-green-emitting ZnB 2 O 4 :Mn 2+ phosphor encourages the enhancement of hue uniformity and illumination effectiveness in MCW-LEDs with mean correlated hue heats (CCTs) of roughly 8500 K, though the color quality scale is gradually deteriorating. It is possible to successfully achieve such amazing MCW-LED performance if we choose the right concentration and size of ZnB 2 O 4 :Mn 2+ .