LED Lighting Conditions Research Articles

Day–night expression patterns of opsin genes in the coral Acropora digitifera under natural and LED light conditions

Day–night expression patterns of opsin genes in the coral Acropora digitifera under natural and LED light conditions

Precisely Controlling Polymer Acceptors with Weak Intramolecular Charge Transfer Effect and Superior Coplanarity for Efficient Indoor All-Polymer Solar Cells with over 27% Efficiency.

Indoor photovoltaics (IPVs) are garnering increasing attention from both the academic and industrial communities due to the pressing demand of the ecosystem of Internet-of-Things. All-polymer solar cells (all-PSCs), emerging as a sub-type of organic photovoltaics, with the merits of great film-forming properties, remarkable morphological and light stability, hold great promise to simultaneously achieve high efficiency and long-term operation in IPV's application. However, the dearth of polymer acceptors with medium-bandgap has impeded the rapid development of indoor all-PSCs. Herein, a highly efficient medium-bandgap polymer acceptor (PYFO-V) is reported through the synergistic effects of side chain engineering and linkage modulation and applied for indoor all-PSCs operation. As a result, the PM6:PYFO-V-based indoor all-PSC yields the highest efficiency of 27.1% under LED light condition, marking the highest value for reported binary indoor all-PSCs to date. More importantly, the blade-coated devices using non-halogenated solvent (o-xylene) maintain an efficiency of over 23%, demonstrating the potential for industry-scale fabrication. This work not only highlights the importance of fine-tuning intramolecular charge transfer effect and intrachain coplanarity in developing high-performance medium-bandgap polymer acceptors but also provides a highly efficient strategy for indoor all-PSC application.

Chasing Light: How Dichromatic LEDs Affect the Elemental Profile of Gongolaria barbata

This study aims to investigate the influence of three different dichromatic LED light sources and varying photoperiod durations on the mineral content and trace element compositions in cultivated Gongolaria barbata under controlled culture conditions. During the experiment, red-blue (RB), blue-green (BG), red-green (RG) and fluorescent lights were examined at 16:16, 12:12, and 8:16 Light: Dark (L:D) photoperiods, and at 150 μmol photon m-2 s-1 intensity of light in all treatments. The elemental compositions of the thallus samples were analyzed for Mg, Ca, K, Na, P, Zn, Mo, Cu, Mn, Cr, Co, Cd, Fe, and As.. Our results showed that macro element and trace element compositions significantly varied among different experimental groups. Regarding the order of abundance, macroelements were ranked as follows: K > Na > Ca > Mg > P. Meanwhile, trace elements followed this order: As > Zn > Mn > Cr > Co > Cu > Cd > Mo > Fe. Among the experiment groups, the highest value of the macro elements was recorded as 1041.3±22.2 mg kg-1 for K, and the lowest value was 26.61±0.02 mg kg-1 for the P. Among the trace elements, for As, the highest value was recorded as 1339.86±5.27 µg kg -1, and the lowest was determined at 1.93±0.04 mg kg-1 for the Fe. The findings highlight that LED lighting conditions can significantly influence the elemental composition of G. barbata.

A New Small-Size Camera with Built-In Specific-Wavelength LED Lighting for Evaluating Chlorophyll Status of Fruit Trees.

To produce high-quality crops, not only excellent cultivation techniques but also accurate nutrient management techniques are important. In recent years, many nondestructive tools such as the chlorophyll meter "SPAD" and the leaf nitrogen meter "Agri Expert CCN" have been developed for measuring crop leaf chlorophyll and nitrogen contents. However, such devices are still relatively expensive for individual farmers. In this research, we developed a low-cost and small-size camera with built-in LEDs of several specific wavelengths for evaluating the nutrient status of fruit trees. A total of 2 camera prototypes were developed by integrating 3 independent LEDs of specific wavelengths (Camera 1: 950 nm, 660 nm and 560 nm; Camera 2: 950 nm, 660 nm and 727 nm) into the device. In addition, a simple software tool was developed to enable the camera to capture leaf images under different LED lighting conditions. Using the prototypes, we acquired images of apple leaves and investigated the possibility of using the images to estimate the leaf nutrient status indicator SPAD (chlorophyll) and CCN (nitrogen) values obtained using the above-mentioned standard tools. The results indicate that the Camera 1 prototype is superior to the Camera 2 prototype and can potentially be applied to the evaluation of nutrient status in apple leaves.

Effects of different LED lighting conditions on young horses during trailer loading and stationary confinement

Effects of different LED lighting conditions on young horses during trailer loading and stationary confinement

The Effect of Correlated Color Temperature and Illumination Level of LED Lighting on Visual Comfort during Sustained Attention Activities

LED lighting has been widely used in various scenes, but there are few studies on the impact of LED lighting on visual comfort in sustained attention tasks. This paper aims to explore the influence of correlated color temperature (CCT) and illuminance level in LED lighting parameters on human visual comfort. We selected 46 healthy college students (23 male and 23 female). The ages ranged from 22 to 26 years old (average age was 24.2 years). Electroencephalogram (EEG) signals, sustained attention to response test (SART) parameters and subjective evaluation parameters of subjects performing sustained attention tasks under LED lighting were obtained. The results under different conditions were compared, and the effects of experimental lighting parameters on visual comfort were discussed. The results showed that the LED lighting with CCT of 3300 K and illuminance of 300 lx was more comfortable than other combined conditions. In the subjective perception of subjects, 4000 K CCT also had good visual comfort evaluation and caused good task performance. Therefore, our study showed that in sustained attention tasks, when LED lighting conditions were CCT of 3300 and 4300 K and illuminance level was 300 lx, the visual comfort of the subjects was better.

Growing medicinal plant Artemisia in vertical farming under different LED light conditions

Growing medicinal plant <i>Artemisia</i> in vertical farming under different LED light conditions

Investigation of LED Light Qualities for Peppermint (Mentha x Piperita L.) Cultivation Focusing on Plant Quality and Consumer Safety Aspects

To understand how peppermint responds to different LED light qualities during the early vegetative phase, peppermints were illuminated with three different LED light conditions (RB = Red/Blue, RGB = Red/Green/Blue, SUN = artificial sunlight closely resembling the terrestrial sunlight spectrum between 380 and 780 nm) in an automated vertical cultivation system. RB resulted in compact growth, whereas both green-containing lighting conditions induced excessive stem and side branch elongations and significant leaf expansions. Although peppermint plants achieved marketable appearances regardless of lighting condition, essential oil (EO) compositions with highly elevated amounts of pulegone and menthofuran did not meet consumer safety requirements. Both artificial SUN and RB spectra showed lower concentrations of pulegone in the EO at 41 and 43%, respectively, than detected under RGB at more than 49%. Reasons for this undesirable EO composition are discussed as a result of the lighting conditions applied and the early harvest time, leading to an incomplete reduction of pulegone to menthone during biosynthesis. Based on these findings, aromatic peppermint cultivation under LEDs can be improved to meet regulatory requirements and highlights the need for analytical quality controls regarding consumer safety to evaluate the applicability of LED lighting for fresh herb productions.

Blue LED lighting improves the postharvest quality of tomato (Solanum lycopersicum L. cv. Zahide F1) fruits

Objective: The objective of this study was to investigate the effects of different wavelengths of LED lighting on the postharvest quality of tomatoes (Solanum lycopersicum L. cv. Zahide) during breaker harvest stages..&#x0D; Material and Methods: Harvested tomato fruits were placed on 500 g polystyrene foam dishes and wrapped with stretch film. They then were stored in 4±1ºC temperature and 85-90% relative humidity for 42 days under the red (R), blue (B), green (G) and white (W) LED light conditions. The fruits stored in the dark were used as control (C). &#x0D; Results: R and W LED treatments increased hue angle value, yellowness index value, and fruit firmness of tomatoes Blue LED lighting, also decreased electrolyte leakage that indicates delaying senescence. It was also found that blue and red LED lighting delayed fruit decay.&#x0D; Conclusion: As a conclusion, it could be satated that the blue LED lighting was found to be more effective than the red, white and green LED light in maintaining the quality of the tomatoes harvested at the breaking stage.

First person – Lana de Vries

ABSTRACTFirst Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping early-career researchers promote themselves alongside their papers. Lana de Vries is first author on ‘Bumblebees land remarkably well in red–blue greenhouse LED light conditions’, published in BiO. Lana is a PhD Candidate in the lab of Dr Florian Muijres at the Experimental Zoology Group, Wageningen University & Research, studying insects, especially social insects like bumblebees, since these kinds of animals can build complex social systems with an organized division of tasks.

Effects of Different Light Sources on Neural Activity of the Paraventricular Nucleus in the Hypothalamus.

Background and Objectives: Physical function is influenced by light irradiation, and interest in the influence of light irradiation on health is high. Light signals are transmitted from the retina to the suprachiasmatic nucleus (SCN) via the retinal hypothalamic tract as non-image vision. Additionally, the SCN projects a nerve to the paraventricular nucleus (PVN) which acts as a stress center. This study examined the influences of three different light sources on neural activity in the PVN region using two different color temperatures. Materials and Methods: Experiments were conducted using twenty-eight Institute of Cancer Research (ICR) mice (10 week old males). Three light sources were used: (1) organic light-emitting diode (OLED) lighting, (2) LED lighting, and (3) fluorescent lighting. We examined the effects of light irradiation from the three light sources using two different color temperatures (2800 K and 4000 K). Perfusion was done 60 min after light irradiation, and then the brain was removed from the mouse for an immunohistochemistry analysis. c-Fos was immunohistochemically visualized as a marker of neural activity in the PVN region. Results: The number of c-Fos-positive cells was found to be significantly lower under OLED lighting and LED lighting conditions than under fluorescent lighting at a color temperature of 2800 K, and significantly lower under OLED lighting than LED lighting conditions at a color temperature of 4000 K. Conclusions: This study reveals that different light sources and color temperatures alter the neural activity of the PVN region. These results suggest that differences in the light source or color temperature may affect the stress response.

Luminescent solar concentrators performing under different light conditions

The use of luminescent solar concentrators (LSCs) is considered a promising option to impart energy harvesting capability to buildings with minimal alternation to the building structure. To fill the gap between fundamental research and practical application, this study investigated the performance (power conversion efficiency, ηLSC and power concentration ratio, C) of the LSCs of different sizes under different light conditions including simulated sunlight condition, outdoor sunny, overcast and raining conditions, and indoor condition employing four different types of light bulbs (i.e., incandescent, halogen, fluorescent and light-emitting diode). It was observed that the LSCs exhibited higher one-sun performance under outdoor sunny condition than under simulated sunlight. Under overcast and raining conditions, ηLSC decreased significantly with the increase of the device size. Under indoor incandescent and halogen light conditions, the LSCs exhibited low ηLSC due to the low percentage of the visible portion in the light spectrum. Surprisingly high ηLSC boosted by 50% compared to the outdoor sunny condition was obtained in the LSCs under fluorescent and LED light conditions. This research suggested very promising application of the LSCs in indoor light energy recycling, which has not been proposed before.

Germination and morphological features of bluestem joint fir (Ephedra equisetina) seeds under different LED light conditions

Germination and morphological features of bluestem joint fir (<i>Ephedra equisetina</i>) seeds under different LED light conditions

Gene expression profiling of astaxanthin and fatty acid pathways in Haematococcus pluvialis in response to different LED lighting conditions

Haematococcus pluvialis is a green microalga of major interest to industry based on its ability to produce large amounts of astaxanthin. Biosynthesis of astaxanthin and its mono- and di-esters was significantly stimulated under 150 μmol m−2 s−1 of white LED (W-150) compared with lower light intensities, but the highest astaxanthin amounts were produced under 70 μmol m−2 s−1 of blue LED (B-70). Transcripts of astaxanthin biosynthesis genes psy, crtO, and bkt2 were upregulated under W-150, while psy, lcy, crtO, and crtR-B were upregulated by B-70. Total fatty acid content and biosynthesis genes fata and all dgat genes were induced under W-150, while C18:3n6 biosynthesis and dgat2a expression were specifically stimulated by B-70 which was correlated to astaxanthin ester biosynthesis. Nitrogen starvation, various LEDs and the identified upregulated genes may provide useful tools for future metabolic engineering to significantly increase free astaxanthin, its esters and fatty acid precursors in H. pluvialis.

The influence of LED lighting on task accuracy: time of day, gender and myopia effects

In this research, task errors were obtained during performance of a marker location task in which the markers were shown on a computer screen under nine LED lighting conditions; three illuminances (100, 300 and 500 lx) and three color temperatures (3000, 4500 and 6500 K). A total of 47 students participated voluntarily in these tasks. The results showed that task errors in the morning were small and nearly constant across the nine lighting conditions. However in the afternoon, the task errors were significantly larger and varied across lighting conditions. The largest errors for the afternoon session occurred when the color temperature was 4500 K and illuminance 500 lx. There were significant differences between task errors in the morning and afternoon sessions. No significant difference between females and males was found. Task errors for high myopia students were significantly larger than for the low myopia students under the same lighting conditions. In summary, the influence of LED lighting on task accuracy during office hours was not gender dependent, but was time of day and myopia dependent.

Effects of photopic and cirtopic illumination on steady state pupil sizes

The conventional view was that cones are responsible for pupil constriction in photopic lighting conditions. With the discovery of intrinsically photosensitive retinal ganglion cells (ipRGC), it was found that signals from ipRGCs along with cones mediated the pupil light reflex in photopic lighting conditions. Although both signals contributed, it was unclear how these signals were summed. In the work reported here, steady-state pupil size was measured with an infrared camera under LED lighting conditions with different color temperatures and luminance. A formula was then derived for pupil size according to the linear summation of cirtopic and photopic luminance. This formula allowed direct calculations to predict pupil size well when LED photopic luminance ranged from about 50cd/m2 to 300cd/m2, which is the general luminance level range for computer and smartphone screens.

A novel photo-biological engineering method for Salvia miltiorrhiza-mediated fabrication of silver nanoparticles using LED lights sources and its effectiveness against Aedes aegypti mosquito larvae and microbial pathogens

In this study, Salvia miltiorrhiza-synthesized Ag nanoparticles (AgNPs) fabricated using sunlight or various LED lights were studied for their biophysical features and evaluated as larvicides against Aedes aegypti mosquitoes and growth inhibitors on different species of microbial pathogens. AgNPs production post-exposure to sunlight or different LED light conditions (i.e. blue, red, green, and white) was confirmed by characteristic surface Plasmon resonance (SPR) at maximum λ of 430, 420, 460, 450, and 460 nm, respectively. Optimization of pH, reducing extract concentration, metal ion concentration and time elapsed from the nano-biosynthesis was achieved. High-resolution transmission electron microscopy (HR-TEM) showed that most AgNPs was spherical, triangular and oval, with average size of 18.5, 28.02, 50.22, 16.26 and 10.12 nm for white, green, red, blue and sunlight, respectively. XRD confirmed the all the obtained AgNPs showed face centered cubic (fcc) crystal lattice. FT-IR analysis of all synthesized AgNPs indicated the involvement of phenol, amine, hydroxyl and amino groups in the reduction of nano-Ag. All tested AgNPs inhibited the growth of Brevibacterium linens (KACC-14346), Propionibacterium acnes (KACC 11946), Staphylococcus aureus (KACC-10768) and Staphylococcus epidermidis. As a general trend, larvicidal assays conducted on dengue and Zika virus vector Aedes aegypti showed that, after 48 h of exposure, the toxicity achieved by sunlight-fabricated AgNPs was slightly higher if compared to AgNPs fabricated using various LED lights. Overall, our research highlighted the importance of abiotic parameters, with special reference to light condition, during green nanosynthesis of antimicrobials and larvicides.

The Influence of Tunable LED Lighting Systems on Consumer Food Label Perceptions

A study was conducted in a grocery store simulation lab at a large Mid-Western university to measure consumer perceptions of meat package label design variations under different LED lighting conditions. A quasi-experimental approach using a multi-group between-within subjects’ post-test only design measured participants’ responses to the novel meat labels. Philip’s HUE consumer LED light bulbs were varied with different colors over beef steak package labels from 2700 K (RED) - 7000 K (BLUE). Goose neck lamps over the packages were used to create the display lighting simulations. The researchers determined that there was evidence of label and lighting interactions which influenced consumer perceptions of nutrition label information both between and within subject groups.

Effects of different carbon dioxide and LED lighting levels on the anti-oxidative capabilities of Gynura bicolor DC

Gynura bicolor DC is not only an edible plant but also a kind of traditional Chinese herbal medicine. G. bicolor DC grown in controlled environmental chambers under 3 CO2 concentrations [450 (ambient), 1500 (elevated), 8000 (super-elevated) μmolmol−1] and 3 LED lighting conditions [white (WL), 85% red+15% blue (RB15), 70% red+30% blue (RB30) ] were investigated to reveal plausible antioxidant anabolic responses to CO2 enrichment and LED light quality. Under ambient and elevated CO2 levels, blue light increasing from 15% to 30% was conducive to the accumulation of anthocyanins and total flavonoids, and the antioxidant activity of extract was also increased, but plant biomass was decreased. These results demonstrated that the reinforcement of blue light could induce more antioxidant of secondary metabolites, but depress the effective growth of G. bicolor DC under ambient and elevated CO2 levels. In addition, compared with the ambient and elevated CO2 levels, the increased anthocyanins, total flavonoids contents and antioxidant enzyme activities of G. bicolor DC under super-elevated CO2 level could serve as important components of antioxidative defense mechanism against CO2 stress. Hence, G. bicolor DC might have higher tolerance to CO2 stress.

A Study of Reading Fatigue

Compared to traditional printed books, digital e-book readers may cause consumers to read overtime and reading fatigue or even vision injury. Therefore, it is needed to study on reading fatigue based on different reading illuminants, i.e. under brighter, normal, dim, and LED lighting conditions, and different book content carriers, i.e. printed bond paper, Kindle, and iPad, to evaluate degrees of reading fatigue. Overall, the results showed that the reading illuminants are critical and highly affect vision fatigue; especially the LED light resulted in greater reading fatigue. Printed paper can cause less degree of fatigue or even no vision fatigue at all as long as with sufficient illuminant.