Lighting Research Articles

Low blue-hazard white-light emission based on color-tunable triplet-triplet annihilation upconversion

The commonly used artificial light sources, such as fluorescent lamps and white light-emitting diodes, often have a high ratio of blue light emission, which poses potential blue light hazards, especially one of the main culprits leading to eye diseases. Therefore, developing novel white lighting sources with low blue-hazard is highly appreciated. In this work, an air-stable and color-tunable triplet–triplet annihilation upconversion (TTA-UC) mechanism was proposed to realize the low blue-hazard white-light emission. The proposed design was composed of three primary RGB colors from the annihilator (9,10-diphenylanthracene, DPA), the laser excitation source, and the photosensitizer (palladium (II) octaetylporphyrin, PdOEP), respectively. The introduction of oil-in-water (o/w) microemulsion can effectively block the potential oxygen-induced triplet-quenching and benefit high UC efficiency. Moreover, either raising ambient temperatures or adding isobutanol can activate the UC process to yield white-light emission. Notably, the white-light emission with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.33, 0.33) as well as a low ratio of blue emission (14.2 %) was achieved at an ambient temperature of 42 °C. Therefore, the proposed air-stable TTA-UC mechanism can significantly lower the blue-hazard and provide a novel solution for applications in lighting and display.

Penerapan Bentuk Dinamis Dalam Membangun Suasana Pada Ruang Tunggu RSUD Pandega Pangandaran

The interior design of hospital waiting rooms plays a crucial role in providing comfort and reducing stress for patients and visitors. In a medical environment, the psychological and physical factors of waiting room design can significantly impact the overall user experience. This study aims to explore and implement dynamic design forms in the waiting room of RSUD Pandega Pangandaran to enhance user experience quality. The methodology employed in this research includes field observations to understand the existing conditions, in-depth interviews with users to identify their needs and preferences, and a comprehensive literature review on dynamic interior design, ergonomic principles, and environmental psychology theories. The findings of the study indicate that the use of dynamic forms, combined with soothing color elements, optimal natural and artificial lighting, and ergonomic and flexible furniture arrangements, can significantly improve the comfort and satisfaction of waiting room users. This study emphasizes the importance of a holistic approach in designing hospital waiting rooms that not only focuses on aesthetics but also on functional and psychological aspects to create a more humane environment that supports the healing process

Correspondence: Plain talk about artificial light

Correspondence: Plain talk about artificial light

Exploration of Energy-Saving Technologies in Building Electrical System Design

Green energy conservation is the mainstream trend in the current development of the construction industry. The application of energy-saving technology in building electrical system design can effectively reduce energy consumption, avoid unnecessary energy consumption, and truly achieve energy conservation and environmental protection. Based on this, the article elaborates on the principles of energy-saving design in building electrical systems, and actively explores the application of energy-saving technologies from different perspectives such as optimizing power supply and distribution system design, adopting high-efficiency energy-saving lighting equipment, applying renewable energy, promoting smart home technology, and improving the efficiency of building electrical equipment.

Application of green building thermal energy conservation based on light imaging equipment in landscape optimization of waterfront space

As the global focus on sustainable development intensifies, green buildings have become an important way to reduce energy consumption and improve environmental quality. The purpose of this study is to explore the application of technology based on optical imaging equipment in the heat saving of green buildings, especially in the landscape optimization of waterfront space, and evaluate its effectiveness and feasibility. In this study, light imaging equipment was used to monitor the heat distribution of different green buildings in the waterfront space, and combined with environmental data and energy consumption, the influence of architectural design and landscape configuration on heat energy conservation was analyzed. Through case study and quantitative analysis, the optimization effect of different design schemes on thermal effect is evaluated. The study found that rational allocation of buildings and surrounding landscape can significantly reduce heat loss, reflecting the importance of heat management. Light imaging technology effectively reveals the thermal energy dynamics of buildings under different weather conditions, verifying the potential of green buildings to reduce energy consumption. Therefore, the research based on optical imaging equipment provides a new perspective and method for the energy saving of green buildings in the waterfront space, and demonstrates the important role of optimizing landscape design in improving building energy efficiency.

Insights into the Effect of Light Pollution on Mental Health: Focus on Affective Disorders-A Narrative Review.

The presence of artificial light at night has emerged as an anthropogenic stressor in recent years. Various sources of light pollution have been shown to affect circadian physiology with serious consequences for metabolic pathways, possibly disrupting pineal melatonin production with multiple adverse health effects. The suppression of melatonin at night may also affect human mental health and contribute to the development or exacerbation of psychiatric disorders in vulnerable individuals. Due to the high burden of circadian disruption in affective disorders, it has been hypothesized that light pollution impacts mental health, mainly affecting mood regulation. Hence, the aim of this review was to critically summarize the evidence on the effects of light pollution on mood symptoms, with a particular focus on the role of circadian rhythms in mediating this relationship. We conducted a narrative review of the literature in the PubMed, Scopus, and Web of Science datasets. After the screening process, eighteen papers were eligible for inclusion. The results clearly indicate a link between light pollution and the development of affective symptoms, with a central role of sleep disturbances in the emergence of mood alterations. Risk perception also represents a crucial topic, possibly modulating the development of affective symptoms in response to light pollution. The results of this review should encourage a multidisciplinary approach to the design of healthier environments, including lighting conditions among the key determinants of human mental health.

Light and Motion: Effects of Light Conditions and mEDI on Activity and Motion Area under a Sky-Lighting Machine

ABSTRACT We investigated whether differences in light levels and spectral properties have effects on motion. Twenty-two participants, divided into groups of two, experienced the same room in two diffused light conditions (daylight [DL] or static artificial light [AL]), which were experienced in a repeated measures design layout, controlled for order. Both light conditions offered a stimulus of at least 250 melanopic equivalent daylight illuminance (mEDI) lux, without a view. Participants were observed during an individual reading session and a collaborative construction game session. We measured the connectivity of the built structures, activity by actigraphy, and we automatically extracted motion area and quantity of motion from video analysis. We found a correlation between mEDI values in the two light conditions (DL or AL) and activity and a correlation between light condition and motion area. Diffuse daylight conditions were correlated with lower activity and less extended motion than a diffuse static condition at levels recommended for office lighting and to ensure alerting responses. Indeed, static AL was found to be related to increased spatial exploration, which might indicate restlessness, and high mEDI to a more composed motion. Actigraphy measurements correlate with quantity of motion values; therefore, the two methods provided comparable results. Results also showed a high correlation between all photometric values in the daylight condition. These findings offer arguments for favoring DL conditions in the design of places where it is desirable to avoid fidgetiness, like educational institutions, and to support composed motion, like medical institutions.

MONITORING OF LIGHT POLLUTION IN THE TRANSCARPATHIAN REGION

Light pollution first gained attention when people realized they could no longer see the night sky as they once did due to excess visible and ultraviolet light from cities. However, in recent years, it has become clear that artificial night lighting worries not only astronomers. Studies have shown that artificial night lighting harms a variety of animals. To preserve the natural darkness of the sky in the world, parks of the dark (or starry) sky are created, which are the areas of a unique natural environment that protect the natural night darkness from pollution by artificial light. They are the equivalent of nature reserves — territories with exceptional natural value. They perform protective functions for the darkest corners of our planet, where the night environment is not dis- turbed by artificial light. These parks perform not only ecological but also educational functions. Darkness protection is slowly being incorporated into existing conservation areas such as national parks. Darkness is a natural resource that needs protection. In 2016, Transcarpathian Dark Sky Park was created. For its registration and entry into the International Association of Dark Sky Parks, the brightness of the night sky was measured in different places in this park to determine the state of light pollution in this area. The results of the measurements fully satisfied the requirements for dark sky parks. In all places of the Transcarpath- ian Dark Sky Park where we performed measurements, the average value of the background of the night sky was ~21.50 mag/ arcsec 2 . In 2021, an application for registration of Transcarpathian Dark Sky Park in the International Association of Dark Sky Parks was accepted. Research into the state of light pollution on the outskirts of the Dark Sky Park is also ongoing, namely at two optical observation stations — Uzhhorod and Derenivka. The results of changes in the background of the night sky in these places over a 40-year time interval are presented.

(Invited) Non-Fullerene Acceptor in Organic Solar Cells Toward Improving Performance as Indoor Light Energy Harvester

Research in organic solar cells aims to develop new materials that improve efficiency. The inception of emerging non-fullerene acceptors (NFAs) by replacing the fullerene counterpart in organic solar cells (OSCs) has pushed the bulk-heterojunction based photovoltaics to achieve efficiencies around 18% [1-6]. In order to produce efficient OSCs, it is required to have donor and acceptor materials with matching absorption bands in the Vis-NIR range, high charge-carrier mobility, and a small energy offset to minimize voltage losses. Mainly, the development of Y7 NFA molecule has improved power conversion efficiencies by pairing selected polymer donors, such as PM6 [7, 8]. Nowadays, OSCs have attracted great attention for being used as indoor light energy harvesters. The organic materials in the active layer can have tuned optical band gaps, providing an absorption spectrum that matches with emission spectra of several indoor lights, e.g., halogen lights, LED (light-emitting diodes), and FLs (fluorescent lamp), which have different emitting spectra [9, 10].The use of OSCs for indoor light harvesting applications is promising for integration into low-power indoor electronic devices from microwatts to milliwatts, such as data transfer systems, alarm systems and distributed controls. Moreover, the OSCs have the possibility to be used with power wireless sensor nodes connected to the Internet of Things. At present, LEDs are the most popular low-light level sources which can be found in offices and homes. The intensity of the light emitted by an artificial light source, per unit area of a surface is called illuminance and measured in units of lux (lx). A level 500 lx is typically recommended for office environments and 200 lx for living room environments.In this research, we have been aiming at the performance and stability over time of organic solar cells under LED illumination using fullerene and non-fullerene acceptors. We have chosen as the indoor illumination source an LED lamp with a color temperature of 3000 K and color rendering index (CRI) > 80 following the protocols ISOS [11]. The LED lamp output illuminances were varied in the range from 200 to 1500 lx. We have used PM6 as polymer donor material due to their absorption spectrum and energy band gaps well-matched to the incident LED spectrum. In order to research the improvement of the performance of OSCs under indoor illumination we have compared PC70BM fullerene acceptor with ITIC-M, Y6-O, and Y7 non-fullerene acceptors. As a result, under 1000 lx illumination we achieved PCEs from ~ 12% using Y6-O, ~ 15% using PC70BM, ~16% using Y7 up to more than 18% efficiency using ITIC-M. The study is performed including optical and electrical characterization with the purpose of understanding the behavior and the transport processes taking place in the device. In future work, we focus on the stability of the encapsulated OSCs under continuous LED illumination following the agreed stability testing protocols to study which active layer turns out to be more stable under these conditions. Acknowledgements: This work was supported by the Ministerio de Ciencia, Innovación y Universidades (MICINN/FEDER) PDI2021-128342OB-I00, by the Agency for Management of University and Research Grants (AGAUR) ref. 2021-SGR-00739, and by the Catalan Institution for Research and Advanced Studies (ICREA) under the ICREA Academia Award. M. Ramírez-Como acknowledge to CONAHCYT ref. BPPA-20220624083033039-2364083.

Bright and early: artificial light affects arrival time, but not group size or vigilance in Little Penguins (Eudyptula minor)

Coastal developments are ever‐expanding and increasing the use of artificial lights within marine environments. Yet there is conflicting research on the impact of artificial lights on seabirds. Here, we experimentally investigated the impacts of artificial white lights on the behaviours (arrival time, group size, number of groups and vigilance) of breeding Little Penguins Eudyptula minor. Little Penguins are central‐place foragers that spend daylight hours foraging at sea and return to their breeding colony after sunset to attend to their chicks or relieve their incubating partners. We exposed Little Penguins returning to their colony at night to either (1) a self‐sustaining white LED floodlight or (2) a control system with a decoy light turned ‘off’. We used two different landing sites (site 1, site 2) that differed in landscape characteristics to assess whether behavioural responses to light were site‐specific. Little Penguins arrived in larger groups at the landing site 2. Regardless of site, we observed fewer groups that arrived earlier when the light was ‘on’. The effects of artificial light (or ‘lack of artificial light’) on the vigilance of Little Penguins were site‐specific, with Little Penguins spending proportionally more time in vigilance when the light was ‘off’ at site 2 compared with site 1. Our results support the idea that artificial lights produced from coastal developments can alter penguin behaviours, but that the effects of artificial lights can be context‐dependent and need to be assessed on a case‐by‐case basis.

Artificial light at night decreases leaf herbivory in typical urban areas.

Artificial light at night (ALAN) is exerting growing pressure on natural ecosystems, but its impact on biological interactions remains unclear. This study aimed to assess how ALAN influences leaf functional traits and herbivory in two prevalent street tree species (Styphnolobium japonicum (L.) Schott and Fraxinus pennsylvanica) through field surveys and paired experiments in the urban areas of Beijing, China. We found that ALAN led to increased leaf toughness and decreased levels of leaf herbivory. Additionally, ALAN showed species-specific effects on leaf nutrients, size as well as defense substances. The findings illustrate that ALAN can significantly alter some key functional traits and ecological processes (nutrient cycling, energy flow). In general, we suggest that high ALAN intensity will be detrimental to the energy flow from urban plants to higher trophic levels, posing a potential threat to the maintenance of biodiversity (e.g., arthropod diversity, bird diversity) in urban ecosystems.

Perceptual illumination-structure patch decomposition for enhancing complex lighted underwater images

Due to the influence of natural and artificial lighting, complicated illuminated underwater images suffer from uneven exposure, accompanied by color cast, low contrast, and blurred details. Existing methods often struggle to brighten dark areas and suppress overexposed areas. To this end, a perceptual illumination-structure patch decomposition (PISPD) model is proposed to enhance complex lighted underwater images. The PISPD method is firstly based on two complementary inputs, including a contrast-enhanced image and a detail-sharpened image. To combine the complementary information of two inputs and balance brightness, the PISPD model decomposes the inputs into four elements: perceptual illumination map, contrast, structure, and average intensity. The perceptual illumination map is used to balance brightness, while the contrast, structure, and average intensity are used to integrate the features of the inputs. Moreover, a weighted edge-preserving factor is introduced in the decomposition-fusion process of contrast, structure, and mean intensity to avoid artifacts. This study also provides a benchmark dataset, namely, CLUID, containing 990 complex lighted underwater images. Experiments with qualitative and quantitative analyses show that our PISPD outperforms eight state-of-the-art approaches.

The influence of abiotic factors on the development of caterpillars of the chestnut transient moth (Cameraria ohridella Deschka & Dimic) in laboratory conditions

Goal. To investigate the effect of abiotic factors on the duration of development of the caterpillars of the chestnut transient moth, and the ability of the caterpillars to penetrate another leaf of bitter chestnut in laboratory conditions. Methods. In laboratory conditions, experiments were conducted to determine the duration of development of moth caterpillars at temperatures of 15, 20, 25, 30°C, with and without illumination. Chestnut moth caterpillars of different ages were previously selected in natural conditions. In the laboratory, they were placed in thermostats according to their age (10 specimens each), and kept at the appropriate temperature until pupation. To test their ability to re-penetrate the leaves, caterpillars of different ages were removed from the primary leaf and planted on another. Artificial lighting was applied (round the clock) using 4 fluorescent lamps PHILIPS TLD18W/54-765 with a power of 18 W. The experiment was repeated 10 times. Accounting was carried out daily. Statistical processing of data was carried out according to generally accepted methods. Results. During the experiment, it was determined that moth caterpillars are not able to re-enter another chestnut leaf. During the study of the influence of abiotic factors on the duration of the development of caterpillars, it became known that under a temperature regime of 15°C and without lighting, their survival is significantly lower than with lighting. In conditions of complete darkness, 24.4% of the pest was frightened, and with lighting — 58.8%. At the same time, the results of the experiment also showed the importance of the effect of the temperature regime on the maintenance of these insects. Thus, the greatest death of caterpillars was recorded at a temperature of 15°C, when the temperature increased to 20—25°C, this indicator gradually decreased, but when the holding temperature increased to 30°C, the death rate increased again. Thus, we came to the conclusion that it is possible to keep the chestnut moth in laboratory conditions only during the period of its seasonal activity in nature. It is at this time that it becomes possible to study it more thoroughly, and to search for ecological means to reduce the number of chestnuts. Conclusions. Chestnut moth caterpillars are not able to re-enter another chestnut leaf, and their full development is possible only inside mines, where there are optimal conditions for this. The greatest mortality of young caterpillars in laboratory conditions was observed at storage temperatures of 15 and 30°С. The optimal temperature regime for this stage of pest development is 20—25°C. Therefore, keeping these caterpillars in laboratory conditions is effective only during the period of their seasonal activity in nature.

Supplementary Far-Red Light for Photosynthetic Active Radiation Differentially Influences the Photochemical Efficiency and Biomass Accumulation in Greenhouse-Grown Lettuce.

Adding far-red (FR, 700-800 nm) light to photosynthetic active radiation (400-700 nm) proved to be a possible approach to increasing plant biomass accumulation for lettuce production in indoor vertical farms with artificial lighting as a sole-source lighting. However, how FR light addition influences plant growth, development, and metabolic processes and the optimal value of FR photon flux density for greenhouse-grown lettuce under sunlight are still unclear. This work aims to quantify the value of supplementary FR light with different intensities on lettuce morphological and physiological characteristics in a greenhouse. Lettuce 'Dasusheng' (Lactuca sativa L.) was grown in a greenhouse under seven light treatments, including white plus red LEDs with FR photon flux density at 0, 10, 30, 50, 70, and 90 µmol m-2 s-1 (WR, WR + FR10, WR + FR30, WR + FR50, WR + FR70, and WR + FR90, respectively), and lettuce grown with sunlight only was marked as natural light (NL). FR light addition improved the electron transport flux per cross section and performance index (PIabs, PItotal) and decreased the changes in relative variable fluorescence of lettuce leaves compared to plants under NL. Specifically, the PIabs of lettuce leaves were 41%, 41%, 38%, 33%, 26%, and 25% lower under control than in plants under treatments WR + FR90, WR + FR70, WR + FR50, WR + FR30, WR + FR10, and WR, respectively. Leaf number, leaf area, and biomass accumulation of lettuce followed a quadratic function with increasing FR light intensity and were the highest under treatment WR + FR50. The shoot fresh weight and dry weight of lettuce were increased by 111% and 275%, respectively, under treatment WR + FR50 compared to NL. The contents of vitamin C, reducing sugar, total soluble sugar, and starch in lettuce showed a similar trend with biomass accumulation. In conclusion, with commonly used photosynthetic photon flux density (PPFD, 400-700 nm) around 200 μmol m-2 s-1, supplementary FR light intensity of 30~50 μmol m-2 s-1 was suggested to enhance the photochemistry efficiency, biomass accumulation, and carbohydrates' contents in greenhouse-grown lettuce.

Investigation of daylight availability in university dining halls: A case study at the University of Jordan

This study evaluates the availability of daylight inside a university’s dining halls over two days (one sunny and one cloudy) using light meters in real-life sittings. Quantitative monitoring was conducted for horizontal and vertical illuminance levels (HILs and VILs) derived from daylight inside of the dining halls and outside under an unobstructed sky, along with monitoring of the illuminance levels of the artificial light inside. The results are discussed in relation to the minimum recommended HIL value in dining halls of educational buildings (150 lux) set by the Jordanian National Construction Constitution’s lighting code. Further, a questionnaire was conducted with 239 students and employees to evaluate daylight and artificial light from the user’s perspective of the dining halls. HIL, as a dependent variable, was found to vary between the two examined halls, which had different façade fenestrations and hall characteristics. The analysis found that, within the halls, only the area within a 2-metre distance from the north- and west-oriented windows complied with the recommended value, except at breakfast time on a cloudy day. The middle and deepest areas of both halls were significantly lacking in daylight on both cloudy and sunny days. The subjective mean evaluation corresponds with the daylight VILs but contradicts the artificial illuminance levels. As such, subjective needs and preferences may not correspond with objective measurements. This study opens a new path of daylighting research for a largely neglected space: foodservice halls in educational buildings.

Abstract Mo131: Time-Restricted Feeding Normalizes Dim Light at Night-Induced Disruption of Cardiovascular Rhythms in Mice

Background: Light input to the suprachiasmatic nucleus entrains circadian rhythms in physiology and behavior to the day-night cycle. Exposure to light at night in people is associated with cardiometabolic disease. Pre-clinical studies show that artificial light at night, including at very low levels, disrupts day-night rhythms in activity, feeding behavior, heart rate, and blood pressure dipping. Hypothesis: Dim light at night (dLAN) disrupts day-night rhythms in feeding behavior to blunt day-night rhythms in autonomic input to the heart and blood pressure dipping. Methods: Mice (n=5-6/sex) in thermoneutral housing were implanted with telemetry probes to record heart rate, blood pressure, and core body temperature. Autonomic input to the heart was assessed by measuring heart rate and subtracting the temperature-dependent changes in the heart rate after pharmacological inhibition of muscarinic and β-adrenergic receptor activation. Mice were housed in 12 h light: 12 h dark cycles (LD, 200 lux: 0 lux) with ad libitum access to food (LD-ALF), subjected to 12 h light: 12 h dLAN cycles (dLAN-ALF; 200 lux: 5 lux) for two weeks, and then feeding was time-restricted (not calorically restricted) to the dLAN cycle (dLAN-RF). Data were extracted from Ponemah and Clocklab, and statistical analysis was done using GraphPad PRISM software. Results: Compared to LD-ALF mice, dLAN-ALF mice showed reduced amplitudes in day-night activity, feeding, heart rate, and blood pressure rhythms, with males more affected than females (p<0.001). dLAN-ALF male and female mice had decreased amplitudes in the day-night rhythms in autonomic input to the heart. In addition, dLAN-ALF male mice had less blood pressure dipping. dLAN-RF normalized autonomic input to the heart and heart rate in male and female mice (p<0.05, p<0.01, respectively). dLAN-RF also improved blood pressure dipping in male mice (p<0.001). dLAN-RF did not normalize activity rhythms. Conclusion: dLAN disrupts day-night rhythms in activity, feeding, heart rate, and blood pressure dipping in mice, with males being more impacted. Time-restricted feeding to the dLAN cycle normalizes autonomic input to the heart and blood pressure dipping. These data suggest that time-restricted feeding counteracts the light-at-night-induced circadian disruption of cardiovascular function.

Assessing opportunities for enhanced lighting energy conservation via occupancy and daylight monitoring

Efficient energy utilization in buildings is crucial for sustainability. This work proposes an intelligent system that leverages computer vision techniques and CCTV images to assess indoor lighting energy usage based on occupancy, artificial lighting, and daylight conditions. Object detection models - You Only Look Once (YOLO) version 3 (v3) and v8 are employed to detect people, lights, and windows, achieving promising accuracies of 94.9 ​%, 73.3 ​%, and 98.7 ​%, respectively. The system categorizes scenarios as energy-efficient, wasteful, or neutral by integrating these outputs, highlighting opportunities for improving efficiency by harmonizing lighting infrastructure with occupancy and daylight exposure. Performance analyses, including training and validation metrics, are presented. This study demonstrates the potential of computer vision and AI for optimizing energy utilization, enabling sustainable building operation and promoting energy-positive occupant behaviors through sensor-driven methodologies.

Effects of light exposure on human ultra-weak photon emission: Preliminary findings for a pioneering control tool in cosmetics

Currently, the cosmetic industry is developing several treatments based on the use of lights with different wavelengths for anti-ageing strategies and facial rejuvenation. Some lights have been proven to be beneficial for our skincare, but their actual effects require an in-depth analysis.Ultra-weak photon emission (UPE) is a spontaneous, low intensity emission from all living systems produced as a consequence of metabolic reactions (e.g., oxidative metabolism, cell division, photosynthesis, or carcinogenesis). However, it can also be induced by several factors, such as light exposure, wounds, thermal shock, and other stress elements. Thus, measuring human biophotonic emission can open new horizons to explore the real benefits of light therapies, particularly regarding the direct relationship between light exposure and free radicals, such as reactive oxygen species (ROS), which are the main cause of UPE.In this study, the ultra-weak photon emission from a sample of ten human beings after exposure to different lights was studied using red and green lights (artificially produced by an RGB LED lamp) and natural light (directly received from the sun), aiming to assess the UPE changes when directly focusing these types of lights on the skin. Hence, this technique could be proposed as a pioneering control tool in cosmetics, principally with phototherapies.Our preliminary results showed that the UPE response after light stimulation differed when a person was exposed to artificial lights compared to sunlight. Besides, there were relevant variations between women and men that should be deeply examined in further investigations by increasing the number of participating subjects in this experience. Furthermore, it was serendipitously discovered that the presence of certain unusual elements in our body, such as using hyaluronic acid fillers and having white hair (natural or dyed), could change the UPE intensity of our skin.

Low-cost Light-emitting Diode Lights Reduce Production Cost of Bibb Lettuce Grown in Aquaponic Systems

In temperate climates, aquaponic producers must use artificial lighting; however, purchasing light-emitting diode (LED) grow lights can be cost-prohibitive. Two aquaponic trials evaluated low-cost LED lighting for the growth of bibb lettuce (Lactuca sativa var. capitata). In trial 1, seven low-cost LED lights were screened and compared with a high-end LED grow light. The three best-performing lights in terms of total plant biomass produced (grams) and total plant biomass per unit of electricity (grams per square meter per kilowatt-hour) were more intensively evaluated in trial 2. These lights included Spider Farmer SF-2000 [SPI ($300)], Fluence RAZRx [FLU ($364)], Designers Fountain 6-Light 5000 K LED High Bay Light [DES ($100)], and the control NeoSol DS [NEO ($1400)]. After 17 days, lettuce grown under NEO achieved higher (P ≤ 0.05) total biomass (939 g) than DES (812 g). There were no differences (P > 0.05) in the average individual plant weights in any treatment. Plant production efficiency (grams per square meter per kilowatt-hour) was higher in DES than NEO (P ≤ 0.05) but was not different from SPI and FLU (P > 0.05). Results indicate that low-cost LEDs are a viable option for producers looking to reduce investment costs while maintaining adequate plant growth. To further describe potential cost savings for producers, a partial budget analysis evaluated the net change in profits and benefit/cost ratio (BCR) of the experimental lights. All showed improved economic results compared with the control (NEO). These studies indicate that low-cost LED lights can support similar plant growth, at higher energy efficiencies, with better economic viability than more expensive grow lights.

An alternative approach for increasing the visibility of roads

Visibility problems occur on highways that are not sufficiently illuminated at night, endangering traffic safety. Phosphor material, which has a natural glow feature under ultraviolet (UV) light, is planned to increase road visibility in areas with inadequate lighting. Phosphor powder (PP) was used in four different percentages (25%, 50%, 75%, and 100%) as fillers in hot mix asphalt (HMA), reduced to filler size. Asphalt specimens were prepared using a super pave gyratory compactor and super pave volumetric mixture design. Compacted specimens were exposed to artificial 12V UV light for 10-minute intervals in a dark room, and UV light absorption was observed. Visibility analyses were performed on the specimens by taking high-resolution photos with long exposure from a distance of approximately 30 cm from the asphalt specimen using a professional camera. According to the analysis results, the visibility values increased by 200.4%, 378.5%, 538.1%, and 728.5% compared to the reference specimen for substitution rates of 25%, 50%, 75%, and 100%, respectively. Experiments were conducted to determine the behavior of the specimens prepared as phosphorus substitutes in the mixture. After selecting the optimum binder contents, the modified Lottman test procedure was applied to measure the specimens' strength values and moisture sensitivity prepared at optimum ratios. The indirect tensile test results show that the 25% PP-substituted specimen had a better strength value. The tensile strength ratio (TSR) value, the ratio of dry and wet tensile stresses, was determined to have minor moisture sensitivity in the 50% PP-substituted specimen. HWTT was applied to the specimen containing 50% PP content, which exhibited the best TSR ratio, resulting in improved rutting performance compared to the reference specimen.