LED Light Intensity Research Articles

Light sensitivity of the circadian system in the social Highveld mole-rat Cryptomys hottentotus pretoriae.

Highveld mole-rats (Cryptomys hottentotus pretoriae) are social rodents that inhabit networks of subterranean tunnels. In their natural environment, they are rarely exposed to light, and consequently their visual systems have regressed over evolutionary time. However, in the laboratory they display nocturnal activity, suggesting that they are sensitive to changes in ambient illumination. We examined the robustness of the Highveld mole-rat circadian system by assessing its locomotor activity under decreasing light intensities. Mole-rats were subjected to seven consecutive light cycles commencing with a control cycle (overhead fluorescent lighting at 150lx), followed by decreasing LED lighting (500, 300, 100, 10 and 1lx) on a 12h light:12h dark (L:D) photoperiod and finally a constant darkness (DD) cycle. Mole-rats displayed nocturnal activity under the whole range of experimental lighting conditions, with a distinct spike in activity at the end of the dark phase in all cycles. The mole-rats were least active during the control cycle under fluorescent light, locomotor activity increased steadily with decreasing LED light intensities, and the highest activity was exhibited when the light was completely removed. In constant darkness, mole-rats displayed free-running rhythms with periods (τ) ranging from 23.77 to 24.38 h, but was overall very close to 24 h at 24.07 h. Our findings confirm that the Highveld mole-rat has a higher threshold for light compared with aboveground dwelling rodents, which is congruent with previous neurological findings, and has implications for behavioural rhythms.

An Electronic Economic Controller for automatically adjusting the intensity of Solar-Powered LED Street Lightning Systems in rural areas

Using photovoltaic energy for street lighting systems is increasing rapidly in rural areas. An economic and smart controller design for automatic intensity control of LED-based street lights is the main challenge. In this work, an electronic-based controller is proposed for controlling the LED light intensity automatically, considering vehicle movement and atmospheric conditions. A HC-SR501 PIR sensor is used for detection of vehicle movements and to assist the controller in making decisions regarding the brightness of the LED. The proposed LED is operated at three different energy levels, such as 0 W, 10 W, and 30 W. In the daytime, the load will remain off, and at night, the LED will operate at two power levels, 33% and 100%, based on the vehicle occupancy rate. In addition, the proposed controller will enhance the battery lifetime. Furthermore, the proposed work ensures significant savings in energy and operating costs and also favors environmental responsibility. GUB JOURNAL OF SCIENCE AND ENGINEERING, Vol 9(1), 2022 P 58-65

Transcriptome and metabolome analysis reveals mechanism of light intensity modulating iridoid biosynthesis in Gentiana macrophylla Pall.

Light intensity is a key factor affecting the synthesis of secondary metabolites in plants. However, the response mechanisms of metabolites and genes in Gentiana macrophylla under different light intensities have not been determined. In the present study, G. macrophylla seedlings were treated with LED light intensities of 15 µmol/m2/s (low light, LL), 90 µmol/m2/s (medium light, ML), and 200 µmol/m2/s (high light, HL), and leaves were collected on the 5th day for further investigation. A total of 2162 metabolites were detected, in which, the most abundant metabolites were identified as flavonoids, carbohydrates, terpenoids and amino acids. A total of 3313 and 613 differentially expressed genes (DEGs) were identified in the LL and HL groups compared with the ML group, respectively, mainly enriched in KEGG pathways such as carotenoid biosynthesis, carbon metabolism, glycolysis/gluconeogenesis, amino acids biosynthesis, plant MAPK pathway and plant hormone signaling. Besides, the transcription factors of GmMYB5 and GmbHLH20 were determined to be significantly correlated with loganic acid biosynthesis; the expression of photosystem-related enzyme genes was altered under different light intensities, regulating the expression of enzyme genes involved in the carotenoid, chlorophyll, glycolysis and amino acids pathway, then affecting their metabolic biosynthesis. As a result, low light inhibited photosynthesis, delayed glycolysis, thus, increased certain amino acids and decreased loganic acid production, while high light got an opposite trend. Our research contributed significantly to understand the molecular mechanism of light intensity in controlling metabolic accumulation in G. macrophylla.

Effect of the Intensity and Spectral Quality of LED Light on Growth and Quality of Spinach Indoors

Effect of the Intensity and Spectral Quality of LED Light on Growth and Quality of Spinach Indoors

Development of Thin-Film Light-Emitting Devices for Hyper Localized Photodynamic Therapy

In this study, we fabricated a thin-film light-emitting device to apply metronomic photodynamic therapy (PDT) in a weak light emitted by LED chips that showed the PDT effect at the cellular level. Thin-film light-emitting devices can operate an LED chip by the wireless power supply. This device has been developed by exploiting a flexible antenna coil made from Au nanoparticle ink printed on a 5-μm-thick poly(D, L-lactic acid) thin film. The weak light intensity of LED (10∼400 µW/cm2) can direct the cell death regions. Further quantification of mPDT at the cellular level as well as in vivo evaluation, will be carried out.

The Impact of Light Intensities on the Phenotypic Parameters of Cucumber Seedlings at Three Developmental Stages

Industrialized seeding production is one of the most important methods used to raise seedlings in a standardized and efficient manner. However, its consumption of light energy limits its development. In this paper, we studied the effects of LED light intensities (30 (L1), 60 (L2), 90 (L3), 120 (L4), 150 (L5), 180 (L6), and 210 (L7) µmol·m−2·s−1) on the phenotypic parameters and health index of seedlings during different growth stages (cotyledon flattening (CF), one bud and one leaf (OBOL), and one bud and two leaves (OBTL)). Ten out of sixteen plants were selected to measure the parameters in every treatment. The control group was treated with 150 µmol·m−2·s−1 all the time. The results show that the height of the L1-treated plants was greatest during the cotyledon flattening stage. The L7 treatment produced the largest stem diameter, the greatest biomass, the largest leaf area, and the largest leaf circumference, the values of which were 2.61 mm, 3.3 g, 60.67 cm2, and 39.71 cm, respectively. During the one bud and one leaf stage, the L1 treatment produced the tallest plants. The L7 treatment resulted in the largest stem diameter, the greatest biomass, the largest leaf area, and the largest leaf circumference. During the one bud and two leaves stage, the plant height, stem diameter, leaf circumference, and biomass produced of the L6 treatment were the greatest, with values of 68.37 mm, 3.09 mm, 51.54 cm, and 4.47 g. L5 resulted in the largest leaf area (63.91 cm2). The seedling index of the three stages showed an inflection point at the L4 level. The experimental results showed that the light intensity required by the cucumber seedlings was 120 µmol·m−2·s−1, 150 µmol·m−2·s−1, and 120 µmol·m−2·s−1 during the three stages, from the cotyledon flattening stage to the one bud and two leaves stage. The results provide references regarding the light required during the cultivation of cucumber seedlings.

The role of LED supplementary lighting in promoting graft necrotic layer formation in pumpkin-cucumber grafts

The rapid formation of the graft necrotic layer is crucial for preventing organic substance leakage and warding off external infections, significantly enhancing both the speed and quality of graft healing. This study investigates the impact of LED supplementary lighting on pumpkin-cucumber grafts, unveiling the molecular processes underlying necrotic layer formation. Specifically, three replications were conducted, where post-grafting cucumber seedlings were placed separately in healing chambers with LED light intensities of 0 μmol/(m2·s) and 50 ± 1 μmol/(m2·s) for three days. Anatomical observations, enzyme activity assays, energy product content detection, and a more comprehensive transcriptome sequencing analysis on the graft union of the rootstock and scion were conducted. Anatomical observations revealed that LED supplementary lighting accelerates the formation of the pumpkin-cucumber graft necrotic layer, establishing a complete layer by the second day post-grafting, one day earlier than the control. Additionally, at day 3 post-grafting, the activities of POD and PPO enzymes at the rootstock-scion junction significantly surpassed the control, exhibiting a remarkable increase of 74.12 % and 48.96 %, respectively (p < 0.01). Moreover, soluble sugar and ATP levels were notably higher at day 3 post-grafting in comparison to the control, showing significant differences (p < 0.05). Transcriptomic analysis unveiled that LED supplementary lighting not only enhances scion sugar metabolism but also stimulates the upregulation of sugar synthesis genes (SPP1, RPV1) and starch synthesis genes (AGPS1, WAXY, SBEⅡ), while downregulating the starch degradation gene LECRK71 when compared to the control. This orchestrated modulation leads to the accumulation of sugars and starch, providing substantial energy and material foundation for necrotic layer formation. Furthermore, LED supplementation also influences the hormone signaling transduction pathway in the scion, notably upregulating the gene Os01g0656200 involved in abscisic acid signaling when compared to the control, thereby furthering the formation of the necrotic layer. Overall, our research showed that LED supplementary lighting accelerates the formation of the necrotic layer in pumpkin-cucumber grafts by enhancing enzyme activities, sugar metabolism, genetic pathways related to starch accumulation, and influencing hormone signal transduction pathways, notably upregulating genes involved in abscisic acid signaling, providing a robust molecular foundation for early necrotic layer development compared to control conditions. These research findings not only provide a valuable reference for understanding graft healing mechanisms but also demonstrate the promising prospects of LED modern seedling technology. Additionally, the research, which is limited to specific pumpkin and cucumber varieties in graft experiments, necessitates further exploration to validate its broader applicability across diverse plant varieties and grafting methods.

A High-Resolution LED Stimulator for Steady-State Visual Stimulation: Customizable, Affordable, and Open Source.

Visually evoked steady-state potentials (SSVEPs) are neural responses elicited by visual stimuli oscillating at specific frequencies. In this study, we introduce a novel LED stimulator system explicitly designed for steady-state visual stimulation, offering precise control over visual stimulus parameters, including frequency resolution, luminance, and the ability to control the phase at the end of the stimulation. The LED stimulator provides a personalized, modular, and affordable option for experimental setups. Based on the Teensy 3.2 board, the stimulator utilizes direct digital synthesis and pulse width modulation techniques to control the LEDs. We validated its performance through four experiments: the first two measured LED light intensities directly, while the last two assessed the stimulator's impact on EEG recordings. The results demonstrate that the stimulator can deliver a stimulus suitable for generating SSVEPs with the desired frequency and phase resolution. As an open source resource, we provide comprehensive documentation, including all necessary codes and electrical diagrams, which facilitates the system's replication and adaptation for specific experimental requirements, enhancing its potential for widespread use in the field of neuroscience setups.

Growth, Triterpene Glycosides, and Antioxidant Activities of Centella asiatica L. Urban Grown in a Controlled Environment with Different Nutrient Solution Formulations and LED Light Intensities

Nutrients and light are critical factors for sustained Centella asiatica L. Urban production under a controlled environment. The growth, triterpene glycosides, and antioxidant activities of C. asiatica grown under a controlled environment with different nutrient solution formulations (NFFs) and LED light intensities were investigated. Four different NSFs were tested on plant growth, bioactive compounds, and their activities in a conventional greenhouse. The results showed that the plants grown with Houghland and Arnon solution exhibited better growth performance, whereas the use of Resh’s Tropical Dry Summer solution led to increased bioactive compounds and their activities. Subsequently, Resh’s Tropical Dry Summer solution was selected to evaluate the effect of light intensity in a controlled environment. Plants were grown under three LED light intensities (110, 220, and 330 µmol/m2/s PPFD) compared with fluorescent and natural lights (45 and 326 µmol/m2/s PPFD, respectively). We found that light intensity had the strongest influence on growth, triterpene glycosides, and antioxidant activities. Significantly higher values of the most studied parameters were observed in plants grown under high light intensity compared to those grown under low light intensity. The optimal light intensity was 330 µmol/m2/s PPFD, representing an efficient approach for commercially producing this medicinal plant with a higher yield and medicinal properties in a controlled environment.

Illumination Effects on Bacteriorhodopsin Accumulation in Archaeon Halobacterium Halobium

Highlights Effects of varying illumination conditions, including light intensity, light color, and illumination pattern on archaeon Halobacterium halobium growth and bacteriorhodopsin (BR) accumulation were first evaluated. LED green light was much more energy-efficient than the red and blue lights in this research. If energy consumption was not a concern, LED blue and red lights (or their combinations) were more effective for cell growth and BR accumulation, respectively, with a similar light intensity. Abstract. This study was to understand the effect of LED light intensity, color, and illumination pattern on the growth of and bacteriorhodopsin (BR) accumulation in archaeon Halobacterium halobium. Experimental results showed that archaeon growth and BR content increased with increasing white light intensity. Green and white LED lights were found to be the most effective for archaeon growth and BR accumulation; here, effectiveness is defined based on photons shined on the bioreactor. The 12-h light/12-h dark cycle illumination pattern resulted in longer lag phase but achieved higher final cell growth and BR accumulation than continuous white light or an instant flash of light/dark illumination. The fade pattern that had smooth transitioning among green, blue, and red lights was better than the jump pattern without transitioning. The highest cell dry weight and BR content of H. halobium were 1.84 g l-1 and 11.76 mg l-1, respectively, under 29.85 µmol/m2s LED white light illumination. The green LED light of 1.39 µmol/m2s had the highest energy-specific conversion effectiveness and saved energy consumption by 84 and 87% per cell biomass and BR dry weight, respectively, compared to the worst case of LED white light of 29.85 µmol/m2s. Keywords: Archaeon, Bacteriorhodopsin, Halobacterium halobium, Illumination pattern, LED light, Light color.

Using Spatial Modeling to Evaluate LED Light Intensity and Uniformity in Commercial Broiler Houses during Brooding and Tunnel Conditions

Highlights During brooding, more than 97% of the floor area of new broiler houses was above target light intensity, however, in aged houses less than 0.2% of the floor area was above the target. During tunnel conditions, less than 6% of the floor area met the target light intensity range (0.18–0.22 lx) for both aged and new houses. All floor areas in the fan section exceeded the target light intensity in both aged and new houses in all the farms due to light intrusion from the tunnel fans. Bulbs need to be periodically replaced to meet minimum target levels during brooding and light dimmer adjustments need to be made to meet light intensity targets during tunnel ventilation. Abstract. Commercial broiler companies set specific light intensities and photoperiods during different stages of live production to manage bird behavior and growth and to support health and welfare. However, it is currently unknown how much of the floor area in commercial houses is within the target levels set by companies. Therefore, a field survey of twenty 18.3 × 152.4 m broiler houses on five farms was performed to evaluate in-situ light intensity and uniformity in two house sections during brooding [evaporative pad section (pad) and the middle of the house section (mid)] and three sections during tunnel ventilation [pad, mid, and tunnel exhaust fan section (fan)]. Houses ranged in age from new (never used) to aged (5–8 years old). Light intensity measurements were recorded at 70 locations in each of the house sections (140 per house during brooding; 210 per house during tunnel). For tunnel mode, target light intensity values were categorized into above target (&amp;gt;0.22), within target (0.18–0.22 lx), and below target (&amp;lt;0.18 lx). For brooding mode, target light intensity values were below target (&amp;lt;43 lx) and within target (=43 lx). Geostatistics was used to map and calculate the percentage of floor area above, below, or within target thresholds. During brooding and tunnel conditions, the percent of floor area below target (&amp;lt;43 lx and &amp;lt;0.18 lx, respectively) was higher for aged houses than for new houses in the pad and midsections. All the floor area in the fan section was above target due to light intrusion from operating fans. During tunnel ventilation in the new houses, 4.5%, 6.0%, and 0.0% of the floor area at the pad, center, and fan sections, respectively, were within the 0.18 to 0.22 lx target threshold. However, in the aged houses, only 0.6%, 0.7%, and 0.0% of the floor area at the pad, center, and fan sections, respectively, were within the target range. This research illustrates that the newer houses did a better job at meeting or exceeding target light intensities and that very little of the floor area in new and aged houses during tunnel ventilation was within a 10% threshold of target intensities. Lack of light dimmer adjustment to account for lumen depreciation and accumulation of dust on the bulbs in the aged house most likely led to the lower overall light intensities. Because brood bulbs have a 100% lumen capacity and are not dimmed, a deep cleaning of the bulbs and periodic replacement are recommended if they are not reaching lighting targets. Periodic checking of light intensity is recommended, especially in older houses. Keywords: Broilers, House age, Light intensity, Spatial variation, Target.

Application of an artificial neural network coupled to a genetic algorithm for the production of polyphenols in Parachlorella kessleri grown under mixotrophic conditions

Microalgae are vital sources of high-value compounds, like polyphenols. Boosting polyphenol production requires considering diverse factors and their impacts on synthesis. This study aims to optimise polyphenol yield in microalga Parachlorella kessleri using an artificial neural network coupled with a genetic algorithm (ANN-GA). P. kessleri was grown under mixotrophic conditions and subjected to 13 experimental treatments. Factors studied included glucose, NaNO3, KH2PO4, LED light wavelength, intensity, and photoperiod. Total polyphenol concentration was quantified with Folin-Ciocalteu reagent; the polyphenol profile was obtained via HPLC. A database was constructed for ANN training to predict polyphenol production. Developed models were compared using indicators: coefficient of determination (R2pred), Mean Absolute Error (MAE), and Mean Square Error (MSE). Optimal models were fine-tuned with a genetic algorithm and validated using randomised experiments. The optimal ANN architecture for P. kessleri polyphenol production is: 6 inputs, 4 hidden layers, 6 neurons per layer, one output. This design achieved high prediction accuracy (R2 = 0.93). The genetically algorithm-optimised ANN model has these conditions: 26.60 g/L glucose; 1.42 g/L NaNO3; 0.59 g/L KH2PO4; white light; 1000 lx light intensity; 12:12 photoperiod. In experimental validation, 28 mg gallic acid equivalents per gram dry weight (GAE/g DW) were obtained, surpassing all models. An ANN-GA optimisation procedure was used for the first time for polyphenol production in P. kessleri. The model under mixotrophic conditions showed higher polyphenol production than autotrophic conditions. Polyphenol composition in P. kessleri varied between autotrophic and mixotrophic cultures, indicating inducible polyphenol production. The ANN-GA approach for polyphenol production in P. kessleri proved effective, with potential for maximising other high-value microalgae metabolites.

Influence of the spectral composition of light on the morphogenesis of seedlings of &lt;i&gt;Myrtus communis&lt;/i&gt; L. and &lt;i&gt;Psidium cattleianum&lt;/i&gt; Sabine (&lt;i&gt;Myrtaceae&lt;/i&gt; Juss.) in a small pot greenhouse culture

The influence of the intensity and spectral composition of LED and fluorescent (FL) light on the morphogenesis of Myrtus communis L. and Psidium cattleianum Sabine (Myrtaceae) seedlings in a small pot greenhouse culture in the Central Botanical Garden of the National Academy of Sciences of Belarus (CBG) was studied. It was shown that in terms of plant height, the number and total surface of leaves, as well as the specific dry weight of the leaf, seedlings of both species over 120 cultivation days in all variants with irradiation surpassed control plants. The increase in dry weight per 1 cm2 of leaf (mg with respect to the control) that characterizes the photosynthesis productivity was influenced by the spectral composition of radiation, which made it possible to identify interspecies and intervariant differences. The variant with an FL Narva lamp with a total photon flux density PFD = 76.22 µmol/m2/s, with a share of the green spectrum PFD-G = 46.47 %, red – PFD-R = 20.00 % and with the value of the ratio R/FR = 5.77 in the subtropical long-day species M. communis, it was 1.24 mg, while in the tropical short-day species P. cattleianum had only 0.39 mg. In plants irradiated with an LED lamp with a photon flux density PFD = 186.20 µmol/m2/s, with a share of PFD-R = 59.34 %, and at R/FR = 54.43, the growth was 2.60 and 1.93 mg with respect to control, respectively. LED sources are the most efficient in terms of the photosynthesis productivity for both short-day and long day plants.

Growth and Photosynthetic Responses to Increased LED Light Intensity in Korean Ginseng (Panax ginseng C.A. Meyer) Sprouts

Compared to the traditional production of ginseng roots, Panax ginseng sprouts (PGSs) are currently regarded as a substitute due to the relatively short-term culture but still high nutrition. However, the optimal light intensity for the growth ability of PGSs and the characterizations of the responses of PGSs to the light intensity have been largely neglected. This study aimed to determine the influences of the light intensity on the growth, morphogenesis, and photosynthetic responses in PGSs. To this end, two-year-old ginseng rootlets were subjected to one of six light intensities (from 30 to 280 PPFD with 50 PPFD intervals) in a plant factory with artificial lighting (PFAL) via LED light for 10 weeks. On the whole, the recorded parameters of the PGSs showed gradually decreasing trends in response to the increasing light intensities. However, the 80 PPFD-treated PGSs possessed similar or greater root dry weights, leaf areas, carotenoids levels, and photosynthesis (the maximal PSII quantum yield) compared to those in the 30 PPFD regime. Additionally, photoinhibition symptoms as evidenced by chlorosis, necrosis, and stunted growth were observed as the light intensity attained 180 PPFD. Thus, 130 PPFD could be considered a safe point for the appearance of photoinhibition in PGSs. Taken together, we show that the light intensity range of 30–80 PPFD is suitable for maximizing the production of PGSs in PFALs.

Flexible optical tactile sensor based on a liquid-membrane lens structure.

Based on the liquid lens focus mechanism, a novel, to the best of our knowledge, optical tactile sensor is designed by taking advantage of the structure simplicity, fast response, and environmental immunity. The design of the tactile sensing mechanism used the liquid-membrane lens structure. To integrate the tactile sensing system, we designed a data acquisition circuit unit. A performance test platform was built, and performance testing and two application demonstrations were conducted. The experiment's result showed that the linear fitting degree was greater than 0.988, the load response time was 0.078s, the target mass was accurately measured, the maximum error was less than 0.02N, and the fine adjustment of the LED light intensity was achieved.

Led lighting intensity effect on biochemical composition of microgreens of white cabbage

In recent years, there has been a trend in Belarus towards a significant increase in demand for the products of microgreens of vegetable crops, including white cabbage, as a source of a wide range of useful substances. At the same time, an important aspect when growing microgreens in a closed controlled environment is lighting, which is both a signal for growth and development and a source of energy for higher plants. Plants adapt to the conditions of the light environment not only via changes in morphophysiological parameters, but also via restructuring their light-collecting complex. One of the most important parameters of the lighting mode is the photon flux density – the intensity of illumination, which significantly affects both the growth of biomass and the accumulation of secondary metabolites. The results of a comparative study of the influence of the intensity of LED lighting are presented (50, 100, 150, 200, 250 μm/m2·s) for the content of chlorophylls, carotenoids and ß-carotene, dry, tannin and pectin substances, free organic, ascorbic and hydroxy acids in the samples of white cabbage microgreens, soluble sugars, the main groups of bioflavonoids – mainly anthocyanins, leucoanthocyanins, catechins, flavonols and the indicator of the sugar acid index. It has been determined that the leading position in the experiment in terms of the integral level of nutritional vitamin value of this product, exceeding that in the control by 1.4 times, belonged to the variant of the experiment with a minimum intensity of LED lighting of 50 μm/m2·s, whereas for the variant with an intensity of lighting of 150 μm/m2·s, a lag in this regard from the control by 1.1 times and, accordingly, from more successful variants of the experiment by 1.2–1.6 times, which allowed to consider it ineffective. The novelty of the research lies in the fact that for the first time in the conditions of the republic, a comprehensive biochemical study of samples of white cabbage grown at different intensities of LED lighting was carried out, which made it possible to recommend this vegetable crop for industrial production of micro-greenery.

Performance of membrane photobioreactor for integrated Spirulina strain cultivation and nutrient removal of membrane bioreactor effluent

Water reuse by wastewater treatment techniques is implemented to promote a circular economy strategy and alleviate water shortage. The microalgae-based wastewater treatment is an environmentally friendly tool to treat secondary or tertiary wastewater by removing the remaining nutrients, primarily dissolved nitrogen (N) and phosphorus (P). This research aimed to study the membrane photobioreactor (MPBR) performance to treat nitrate nitrogen (NO3-N) and phosphate (PO4) that remained in the membrane bioreactor (MBR) effluent by varying hydraulic retention times (HRTs) and solids retention times (SRTs). Bench-scale of MPBR (63 L) was continuously operated by cultivating Spirulina sp. TISTR 8875. The LED light intensity of 3000–5000 lux was provided 24 h daily. The experimental studies evaluated HRTs in the range of 6.4–9.7 days and SRTs at 20, 40, 60, and 80 days, and the microalgae cells were not removed (infinite SRT). The results showed that the HRT range of 7.7–7.8 days and SRT range of 60–80 days exhibited NO3-N and PO4 removal efficiencies of 39.3–40.9% and 43.8–46.6%, respectively, with the NO3-N and PO4 removal rates of 2.47–2.55 and 0.22–0.23 mg/L-d, respectively. In addition, iron (Fe) in the form of FeEDTA, has been added to the microalgae cultivation at a concentration of 0.07 g/L. It was found that Fe plays an essential role in the growth of microalgae and increases nutrient removal efficiency. The experimental results indicate that the cultivation of Spirulina sp. TISTR 8875 is expected to treat nutrients by the MPBR system as a promising water reuse and nutrient recovery potential.

WITHDRAWN: Using spatial modeling to evaluate LED light intensity and uniformity in commercial broiler houses during brooding and tunnel conditions

WITHDRAWN: Using spatial modeling to evaluate LED light intensity and uniformity in commercial broiler houses during brooding and tunnel conditions

Determination of green and red spinach microgreen chlorophyll content using visible spectroscopy and wavelength selection

Microgreens are quickly-grown greens that are suitable for urban areas. The accumulation of chlorophyll in plants is essential for both nutritional compounds and the microgreen’s attractive appearance. A plant factory is a controlled-environment cultivation method that employs LEDs to enhance photosynthesis, vegetative development, seed germination, and chlorophyll accumulation. This work used VIS-NIR for the quantitative determination of chlorophyll content in green and red spinach microgreens grown under four different LED light intensities with four different ratios, with 100% blue, red, and white LED, and 67%:20%:13% of red:blue: white LED, as artificial grow for 12 hours illumination. The performance of MSC, AN, SNV, smoothing, and the first and second Savitzky-Golay’s derivatives (SGD) were examined. PLSR explained accurately predicted R2C, R2P, RMSEC, and RMSEP up to 0.957, 0.892, 1.054, and 1.661 for chlorophyll a using SGD 1st; 0.813, 0.652, 0.979, and 1.338 for chlorophyll b using SNV; and 0.931, 0.876, 1.155, and 1.550 for total chlorophyll using SNV. The wavelength region of 400 to 700 nm was dominant based on the best regression coefficient (β) for predicting green and red spinach microgreens. Results demonstrated that VIS-NIR spectroscopy, combined with chemometric techniques, PLSR, can be used to evaluate the chlorophyll content of green and red spinach microgreens.

Analyzing Sensitivity Characteristics according to Decrease in Intensity of Light from LED Light Source of Photoelectric Spot-Type Detector

After the revision of “Fire Safety Standards for Automatic Fire Alarm System and Visual Alarm Equipment (NFSC 203)” in 2015 made it mandatory to install smoke detectors in apartments and medical facilities, their number has increased significantly. The detector used in the experiment was a photoelectric spot-type analog smoke detector. The experiment was conducted by configuring a real-time smoke monitoring system. In addition, the sensitivity characteristics of the smoke detector according to the decrease in intensity of light were analyzed. This was achieved by controlling the intensity of light related to the lifespan of the LED, a vital component of the smoke detector. When a intensity of LED light decreased by 10%, the sensitivity of the smoke detector decreased by 12.5%. When a intensity of light decreased by 30%, it decreased to 61% of the smoke detector sensitivity value. From these results, An equation for the change in sensitivity of a smoke detector according to the decrease in intensity of light was derived. It was confirmed that when the light intensity of the LED decreases, the sensitivity of the smoke detector decreases by about 37% more than the decrease in light intensity. Therefore, when developing a photoelectric spot-type smoke detector, establishing the LED current-radiation light characteristic curve and the correlation between the current of the light source and the ambient temperature will significantly improve the product's function and post-management.