Purple Light-emitting Diodes Research Articles

Site-Selective Photobromination of O-Acetylated Carbohydrates in Benzotrifluoride.

Ferrier photobromination enables direct synthetic access to valuable 5-C-bromosugars but has limitations that restrict its broader use. The reaction is typically conducted in CCl4 heated at reflux with irradiation by broad spectrum, energy-inefficient heat lamps. Herein, we demonstrate that the reaction proceeds rapidly and efficiently with PhCF3 as a safe and environmentally benign alternative to CCl4 at mild temperatures (≤40 °C) inside a compact photoreactor fitted with purple light-emitting diodes (LEDs).

Responses of kecapi (Sandoricum koetjape Merr.) seedlings under different spectrum and intensity of light emitting diode

Kecapi (Sandoricum koetjape Merr.) is a local fruit belonging to the Meliaceae family. The market price of this fruit is unstable due to inconsistent production and fruit quality. Kecapi’s cultivation system can be improved by modifying the environment in which LED (Light Emitting Diode) is used as artificial light. This study aims to determine changes in morphological, physiological, and anatomical responses to LED light’s different spectrum and intensity levels. The research used a two-factor, completely randomized design (CRD) consisting of an LED spectrum (purple and white) and two light intensities. The results showed the changes in morphological and physiological responses in high-intensity treatment with the white spectrum of LED (WH). The low intensity with the white spectrum of LED (WL) increased leaf chlorophyll content and photosynthesis rate. The anatomical response has in the low-intensity purple LED (PL) treatment. Increased leaf width occurred in high intensity with the purple LED spectrum (PH). Glucose content in the leaf decreased in all treatments, and increased fructose content in the leaf only occurred in the low-intensity purple spectrum of LED treatment.

Consumer reaction to indoor farming using LED lighting technology and the effects of providing information thereon

Indoor vertical farming using artificial light has gained popularity as one solution to food problems. However, prior studies have shown that some consumers have a negative impression that crops are grown in an artificial environment. The increased use of purple Light-Emitting Diode (LED) lighting, which would make the growing environment look more artificial, may exacerbate that negative perception, leading to low acceptance of vertically farmed produce. Given that consumers are increasingly seeing indoor vertical farming directly, for example, in supermarkets and office buildings, it is important to understand how they perceive the use of purple LED lighting to grow crops and whether these perceptions can be improved by learning more about the scientific basis for artificial light cultivation. This study aimed to determine whether purple LED lighting reduces consumers’ perceptions of indoor vertical farming compared to traditional white lighting, and to examine whether providing information on plant growth and artificial light changes those perceptions. We administered a web-based questionnaire to 961 Japanese respondents, and analyzed the response data using analysis of variance and an ordered probit model to explore the factors that define the likability for indoor vertical farming. The results revealed that the color of LED lighting had a limited influence on consumers' perceptions of indoor vertical farming, whereas explaining the principle of plant growth under artificial light improves their perceptions. Additionally, personal factors, such as resistance to novel food technology, trust in food safety, and awareness of indoor vertical farming, had a significant impact on the perceptions. It is crucial to expand opportunities for people to interact with artificial light cultivation and disseminate information about its scientific mechanisms.

Regulation of chloroplast ultrastructure, adventitious bud anatomy and clonal fidelity of in vitro Zingiber officinale var. rubrum Theilade plantlets in response to LED spectral quality

Light quality plays a major role in deciding plant physiological processes during growth and development as it interacts with the photoreceptors to induce a cascade of events with reversible and non-reversible outcomes. Hence, the present study was focused on conducting qualitative analysis on the effects of different light qualities on chloroplast ultrastructure, adventitious bud anatomy, and genetic fidelity of 12 weeks old in vitro Zingiber officinale var. rubrum Theilade. The study was conducted by integrating white (400–700 nm), far-red (720 nm), blue (460 nm), green (530 nm), red (660 nm), and dichromatic purple (400–660 nm) light-emitting diodes (LEDs). Chloroplasts under white, blue, and purple LEDs showed well-developed grana thylakoid and stroma thylakoid. Far-red, green, and red LEDs distorted chloroplast ultrastructure with an accumulation of starch grains. LED mediated spectral quality customised within the visible spectrum retained meristematic characteristics, vascular initiation, and oleoresin accumulation in the adventitious bud. Furthermore, clonal fidelity assessed using direct amplification of minisatellite DNA regions (DAMD) markers revealed genetic similarities of more than 99% for plantlets regenerated under LED irradiation. The results demonstrated that micropropagation systems integrated with LED spectral quality alters plant chloroplast ultrastructure by the effects on starch accumulation but produced normal adventitious bud phenology. A high genetic similarity percentage suggests effective and promising application of LED spectrum to produce true to type in vitro Z. officinale var. rubrum Theilade plantlets.

Purple light-emitting diode (LED) lights controls chlorophyll degradation and enhances nutraceutical quality of postharvest broccoli florets

The aim of this study was to evaluate the effect of white, red, green, yellow, blue and purple LED lights on visual and nutraceutical quality of broccoli florets during storage at 20 °C for 5 days. The results showed that purple LED light exhibited the best effect on reducing yellowing and retaining chlorophyll via down-regulating expression of genes related to chlorophyll degradation, including BoSGR, BoPAO, BoNYC1 and BoRCCR. On the other hand, yellow, blue and purple LED light increased contents of total phenolic and carotenoids compared to darkness. The highest glucoraphanin content was recorded in purple LED light treated broccoli florets, which was supported by the enhanced expression levels of genes related to glucoraphanin biosynthesis. Meanwhile, purple LED light promoted myrosinase activity and its expression, and reduced ESP expression; thus enhanced sulforaphane formation. In conclusion, among all LED lights, purple LED light showed a significant positive effect considering all estimated indicators and would be useful to maintain and improve the quality of broccoli during storage at 20 °C.

Photoinduced Copper-Catalyzed Asymmetric C-O Cross-Coupling.

The construction of carbon-heteroatom bonds is one of the most active areas of research in organic chemistry because the function of organic molecules is often derived from the presence of heteroatoms. Although considerable advances have recently been achieved in radical-involved catalytic asymmetric C-N bond formation, there has been little progress in the corresponding C-O bond-forming processes. Here, we describe a photoinduced copper-catalyzed cross-coupling of readily available oxime esters and 1,3-dienes to generate diversely substituted allylic esters with high regio- and enantioselectivity (>75 examples; up to 95% ee). The reaction proceeds at room temperature under excitation by purple light-emitting diodes (LEDs) and features the use of a single, earth-abundant copper-based chiral catalyst as both the photoredox catalyst for radical generation and the source of asymmetric induction in C-O coupling. Combined experimental and density functional theory (DFT) computational studies suggest the formation of π-allylcopper complexes from redox-active oxime esters as bifunctional reagents and 1,3-dienes through a radical-polar crossover process.

Development of micropropagation system of Zingiber officinale var. rubrum Theilade using different spectrum light-emitting diode (LED) irradiation

Halia Bara, a popular variety of Zingiber officinale Theilade in Malaysia valued for medicinal values was successfully micropropagated using light-emitting diodes (LEDs) to produce disease-free planting materials. This study aimed to establish LED-induced organogenesis of Halia Bara and to evaluate their biochemical profile. Basal part explants were irradiated with white (400−700 nm), far-red (720 nm), blue (460 nm), green (530 nm), red (660 nm), and purple (400–660 nm) LEDs to study the impact of light quality on vegetative growth of 12-week-old Halia Bara plantlets and their biochemical profile such as superoxide dismutase antioxidant enzyme, pigmentation in addition to total carbohydrate content and accumulation of proline amino acid. Generally, shade avoidance syndrome driven growth by red (660 nm) LED significantly promoted shoot length to 12.07 cm producing taller plants with long and thin leaves. The number of shoots (5.57) and leaves (20) were significantly higher on plants irradiated with dichromatic purple (400–660 nm) LED. Root formation of Halia Bara was also significantly promoted by monochromatic red (13.29). However, microshoot formation was fairly enhanced by white, far-red (720 nm), and blue (460 nm) LEDs in the range of 5–5.9 while exhibiting the insignificant difference in green, red, and purple irradiance. First-line defense by superoxide dismutase (SOD) enzyme was significantly upregulated on Halia Bara plantlets irradiated by blue (460 nm) (0.186 ± 0.001 SOD U/mg) and green (530 nm) (0.183 ± 0.001 SOD U/mg). In general, pigmentation such as total chlorophyll (0.516 to 0.541 μg/mL) and carotenoid (1917–2109 μg/g) were notably higher in Halia Bara plants irradiated by white, blue, green, and purple LEDs than the red and far-red irradiation meanwhile porphyrin (14.143 ± 1.930 μg/g) was highly produced following green LED irradiation. Light-regulated accumulation of total carbohydrate and proline were the highest in far-red (109.098 ± 3.223 mg/g) and control white (0.101 ± 0.008 mmol/mg) LED irradiated Halia Bara plants, respectively. In short, vegetative traits and biochemical profile of in vitro Halia Bara is differentially influenced by the quality of light. Based on the photomorphogenetic and physiological traits, the present study emphasizes the suitability of adoption of the LED irradiance for the sustainable production of micropropagated Halia Bara plants to be supplied to small-scale farmers.

Effect of light-emitting diodes (LEDs) on snow crab catch rates in the Barents Sea pot fishery

Abstract Snow crab (Chionoecetes opilio) has become an important species for the Norwegian seafood industry since its first commercial harvest in 2012. However, periodically catch rates can be low, causing a financial strain on the fishery. Thus, improving the catch rate of existing pot designs has the potential to significantly improve the profitability of fishing enterprises. In this study, we investigated whether the addition of low-powered purple and white light-emitting diode (LED) fishing lights inside the pots could improve catch rates of snow crab in the Barents Sea. Results showed that pots with purple lights harvested a 12.8% higher catch per unit effort (CPUE; number of crab per pot) of legal-sized crab, which was significantly more than the control pots (p = 0.035); pots with white lights did not catch significantly more crab (p > 0.05). Pots equipped with only light (no bait) caught very few crabs and were not considered a viable alternative. Although purple LEDs increased snow crab capture, the economic benefits of using underwater lights in pots remains unclear given the high capital investment required.

Light-Emitting Diode Spectral Sensitivity Relationship with Growth, Feed Intake, Meat, and Manure Characteristics in Broilers

Abstract. Light-emitting diode (LED) light sources have high potential for replacing traditional incandescent lamps in broiler production. LEDs with short wavelengths (480 and 560 nm) have been reported to stimulate broiler growth. However, short-wavelength stimuli might also have potential negative effects on husbandry workers, which has restricted the application of LED technology to broiler production. In this study, we investigated the effect of human-friendly yellow LED light (580 nm), which is close to the wavelength of 560 nm and acceptable for humans, on broiler growth response. We further evaluated the effects of various LED lights on the feed intake and manure characteristics of broilers. The following seven light treatments were tested: red LED light (R group), yellow LED light (Y group), green LED light (G group), blue LED light (B group), purple LED light (P group), white LED light (W group), and incandescent bulb light (I group). We used a 12:12 light:dark cycle, as described in our previous study. The feed and water usage of each group were recorded daily, while body weight and manure weight were determined weekly. Manure from each group was sampled for subsequent analysis. We found that the effects of the LEDs on broiler growth were age-related. Broilers in the Y, G, and B groups had similar body weights. However, the relative body weight gain ratio of broilers in the Y group was always greater than those of broilers in the other groups, particularly those in the I group (p = 0.003). The mass ratio of water usage to feed consumption was highest in the R group, whereas the Y group had the lowest mass ratio. Analysis of manure characteristics showed that manure production was positively correlated with feed intake, and broilers in the Y group produced the lowest amount of manure. The water intake of the broilers and the moisture content of the manure were also positively correlated, suggesting that the lower moisture content of the Y group manure might be caused by decreased water intake. These findings suggest that human-friendly yellow LED light might be a good alternative to green LED, blue LED, and incandescent lamps and can successfully be applied to broiler production.

The Effects of Different Wavelengths of Light-Emitting Diodes on the Expression of Reproduction-Related Genes in Goldfish Carassius auratus

We investigated the differences in the expression of the neurohormones kisspeptin (Kiss) and gonadotropin-inhibitory hormone (GnIH) and cytochrome P450 aromatase (P450arom), gonadotropin hormones (GTHs), and sex steroids in the goldfish Carassius auratus exposed to light-emitting diodes (LEDs). The expression levels of Kiss1, Kiss2, G-protein-coupled receptor 54 (GPR54), GTHs, GnIH, and P450arom were compared between the control (white light) and LED-treated goldfish. Furthermore, we measured the plasma levels of follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The levels of Kiss1 mRNA and protein; Kiss2, GPR54, and protein; GTH mRNA; and plasma FSH and LH in the hypothalamus and cultured hypothalamus cells were significantly higher in the green and purple LED treatment groups than in the other groups. These results suggested that red LEDs inhibit the sex maturation hormones, Kiss, GPR54, GTHs, and P450arom, and that GnIH plays a role in the negative regulation of reproductive function in goldfish.

Effect of LED light spectra on circadian rhythms in goldfish Carassius auratus: expression profiles following thermal stress

We investigated the effects of light spectra on circadian rhythms under high thermal stress using red, green and purple light-emitting diodes (LEDs). To assess differences in circadian rhythms during high thermal stress under different LED light spectra, we measured changes in the expression of the melatonin receptor 1 (MT1), period 2 (Per2), and cryptochrome 1 (Cry1) genes and MT1 protein, and in the plasma melatonin and glucose levels. Under high water temperatures and red light conditions, MT1 expression and plasma melatonin and glucose were significantly higher than under low water temperatures and other light spectra, but Per2 and Cry1 expressions were significantly lower. Thus, high water temperatures induce oxidative stress and melatonin acts as an antioxidant molecule. Further, melatonin regulates circadian rhythms via clock genes, and green and purple lights may be suitable for maintaining circadian rhythms in goldfish Carassius auratus, as these wavelengths generally penetrate freshwater more efficiently than does red light.

The stimulatory effect of LED light spectra on genes related to photoreceptors and skin pigmentation in goldfish (Carassius auratus)

This study aimed to assess differences in genes related to skin color of goldfish (Carassius auratus) exposed to light-emitting diodes (LEDs): red, green, and purple. We investigated differences in the expression of mammalian-like melanopsin (Opn4m), rhodopsin (RH), melanin-concentrating hormone (MCH), melanin-concentrating hormone receptor (MCH-R), and proopiomelanocortin (POMC) in goldfish exposed to different LED light spectra. Opn4m, RH, MCH, and MCH-R mRNA levels were significantly higher in the green and purple LED groups than in the white fluorescent bulb (control) and red LED groups. Furthermore, skin cells were isolated to measure the MCH-R mRNA expression levels. The results show that the mRNA expression levels were significantly higher in the green and purple LED groups than in the control and red LED groups. In addition, body weights in the green and purple LED groups were significantly higher than those in the control and red LED groups. However, POMC mRNA expression levels in the green and purple LED groups were significantly lower than those in the control and red LED groups. These results suggest that specific wavelengths regulate fish skin color through neuropeptide hormones and photoreceptors, and POMC, which is related to stress hormones and melatonin, is associated with stress levels as well as skin color.

Luminescent terbium and europium probes for lifetime based sensing of temperature between 0 and 70 °C

Organic europium (III) and terbium (III) complexes (refered to as Eu1, Eu2, and Tb-L1, Tb-L2, respectively) have been synthesized that display bright emission and small bandwidth. Tb-L1 and Tb-L2 show lifetimes in the order of almost 1 ms at room temperature, good color purity, and high relative photoluminescence quantum yields. This makes them excellent probes for sensing temperature via measurement of luminescence lifetime. Probes Eu1, Eu2, Tb-L1 and Tb-L2 were incorporated into various polymer matrices to give sensor films for use as temperature-sensitive paints (TSPs). Eu (III) complexes have the advantage of being effectively excited by purple light-emitting diodes with their peak wavelengths of 405 nm. All TSPs based on these europium and terbium probes display good sensitivities to temperature, in particular, TSP based on Tb-L1 and Tb-L2 can show temperature-lifetime sensitivities of −13.8 μs per °C and − 9.2 μs per °C, respectively. Assuming a precision of ± 1 μs in the determination of lifetime, this will enable temperature to be determined with a precision of around ± 0.1 °C. This temperature dependence is the highest one reported so far for lanthanide complexes.

Determination of octopamine in human plasma by capillary electrophoresis with optical fiber light-emitting diode-induced fluorescence detection

A new analytical method based on capillary electrophoresis (CE) separation and optical fiber light-emitting diode (LED)-induced fluorescence detection has been developed for the determination of octopamine. Naphthalene-2,3-dicarboxaldehyde (NDA) was used for precolumn derivatization of octopamine. The separation and determination of the derivative was performed using a laboratory-built CE system with an optical fiber LED-induced fluorescence detector. Optimal separation was obtained at 20 kV using a background electrolyte solution consisting of 25 mM sodium borate (pH 9.2). High sensitivity detection was achieved by the optical fiber LED-induced fluorescence detection using a purple LED as the excitation source. The limit of detection (signal/noise = 3) for octopamine was 5.0 × 10 −9 M. A calibration curve ranging from 1.0 × 10 −8 to 5.0 × 10 −7 M was shown to be linear. Using this method, the levels of octopamine in human plasma from healthy donors were determined.