Monochromatic Light-emitting Diodes Research Articles

Solution Processed Bilayer Metal Halide White Light Emitting Diodes.

Metal halide perovskites and perovskite-related organic metal halide hybrids (OMHHs) have recently emerged as a new class of luminescent materials for light emitting diodes (LEDs), owing to their unique and remarkable properties, including near-unity photoluminescence quantum efficiencies, highly tunable emission colors, and low temperature solution processing. While substantial progress has been made in developing monochromatic LEDs with electroluminescence across blue, green, red, and near-infrared regions, achieving highly efficient and stable white electroluminescence from a single LED remains a challenging and under-explored area. Here, a facile approach to generating white electroluminescence is reported by combining narrow sky-blue emission from metal halide perovskites and broadband orange/red emission from zero-dimensional (0D) OMHHs. For the proof of concept, utilizing TPPcarz+ passivated two-dimensional (2D) CsPbBr3 nanoplatelets (NPLs) as sky blue emitter and 0D TPPcarzSbBr4 as orange/red emitter (TPPcarz+ = triphenyl (9-phenyl-9H-carbazol-3-yl) phosphonium), white LEDs (WLEDs) with a solution processed bilayer structure have been fabricated to exhibit a peak external quantum efficiency (EQE) of 4.8% and luminance of 1507 cd m-2 at the Commission Internationale de L'Eclairage (CIE) coordinate of (0.32, 0.35). This work opens a new pathway for creating highly efficient and stable WLEDs using metal halide perovskites and related materials.

An open-source LED lamp for use with the LI-6800 photosynthesis system.

Controlling light flux density during carbon dioxide assimilation measurements is essential in photosynthesis research. Commercial lamps are expensive and are based on monochromatic light-emitting diodes (LEDs), which deviate significantly in their spectral distribution compared to sunlight. Using LED-emitted white light with a color temperature similar to sunlight, we developed a cost-effective lamp compatible with the LI-6800 Portable Photosynthesis System. When coupled with customized software, the lamp can be controlled via the LI-6800 console by a user or Python scripts. Testing and calibration show that the lamp meets the quality needed to estimate photosynthesis parameters. The lamp can be built using a basic electronics lab and a 3D printer. Calibration instructions are supplied and only require equipment commonly available at plant science laboratories. The lamp is a cost-effective alternative to perform photosynthesis research coupled with the popular LI-6800 photosynthesis measuring system.

Supplementing with monochromatic blue LED light during the day, rather than at night, increases anthocyanins in the berry skin of grapevine (Vitis vinifera L.).

Supplying monochromatic blue LED light during the day, but not at night, promotes early coloration and improves anthocyanin accumulation in the skin of grape berries. Specific light spectra, such as blue light, are known to promote the biosynthesis and accumulation of anthocyanins in fruit skins. However, research is scarce on whether supplement of blue light during different periods of one day can differ in their effect. Here, we compared the consequences of supplying blue light during the day and night on the accumulation of anthocyanins in pigmented grapevine (Vitis vinifera) berries. Two treatments of supplemented monochromatic blue light were tested, with light emitting diodes (LED) disposed close to the fruit zone, irradiating between 8:00 and 18:00 (Dayblue) or between 20:00 and 6:00 (Nightblue). Under the Dayblue treatment, berry coloration was accelerated and total anthocyanins in berry skins increased faster than the control (CK) and also when compared to the Nightblue condition. In fact, total anthocyanin content was similar between CK and Nightblue. qRT-PCR analysis indicated that Dayblue slightly improved the relative expression of the anthocyanin-structural gene UFGT and its regulator MYBA1. Instead, the expression of the light-reception and -signaling related genes CRY, HY5, HYH, and COP1 rapidly increased under Dayblue. This study provides insights into the effect of supplementing monochromatic LED blue light during the different periods of one day, on anthocyanins accumulation in the berry skin.

A Study on the Irradiance Scintillation Characteristics of Monochromatic LED-Based Visible Light Communication Systems in Weak-to-Strong Turbulence

Atmospheric turbulence causes transmitted light to fade randomly, which results in irradiance scintillation fluctuations in the received signal and significantly affects the quality of wireless optical communication systems. In this paper, we investigate the propagation characteristics of a monochromatic light-emitting diode (LED) light beam through weak-to-strong turbulence. Considering the spatial incoherence of a monochromatic LED light source, the emitted light field of a monochromatic LED light source is represented by a random field multiplied by a deterministic field that follows a Gaussian distribution. Then, based on the extended-Rytov theory, a closed expression for the irradiance scintillation index under weak-to-strong turbulence is derived. In addition, the expression for the fading probability governed by the Gamma–Gamma model is given. Finally, the effects of near-earth atmospheric refractive index structural parameters, signal propagation distances, and working light wavelengths on propagation characteristics of the LED-based VLC system are simulated and compared with those of the laser-based one. The results theoretically confirm that laser light sources are more susceptible to atmospheric turbulence along the propagation path than monochromatic LED light sources. The investigation in this paper can provide theoretical support for the design of visible light communication systems in practical applications.

Solid-state fluorescent carbon dots-based composite optical waveguide film enables transparent and high-performance luminescent solar concentrators

Aggregation-caused quenching (ACQ) is a great obstacle for carbon dots (CDs) to be applied in the photovoltaic fields. In this work, we report that acid-catalyzed hydrolytic condensation of N-[3-(trimethoxysilyl)propyl]ethylenediamine (KH-792) is utilized to generate organosilicon matrices, meanwhile, CDs are covalently linked to the organosilicon matrices to realize solid-state fluorescence via one-step solvothermal method. This approach enables CDs to be uniformly distributed in the organosilicon matrices to produce strong solid-state fluorescence. Most importantly, the obtained blue fluorescent CDs (b-CDs) can be combined with (3-Aminopropyl)triethoxysilane (APTES) to form a highly transparent optical waveguide film on the glass to construct high-performance luminescent solar concentrators (LSCs) with high loading amount. By changing the CDs loading amounts and volume of the coating solution, the transparent LSCs (5 × 5 × 0.2 cm3) with high optical conversion efficiency (ηopt) of 2.83% can be achieved. In addition, the b-CDs powder can be intergrated with 365 nm chips to successfully fabricate monochromatic light-emitting diodes (LEDs). The prepared b-CDs powder with strong solid-state fluorescence shows great potential in photoelectric devices.

Evaluation of broiler performance reared under monochromatic light emitting diode (LED) tubes vis-a-vis incandescent light supplemental lighting

This study was conductedto evaluate the effect of different monochromatic LED lightson the performance of broiler chickens. A total of 120 day-old Lohmann Meat (Indian River) broiler chicks were randomly assigned to three treatment groups: incandescent light (control), red LED light and white LED light, with each group consisting of four replicates of 10 chicks. The chicks exposed to LED lighting showed higher average live weight and liveweight gain compared to the control group, while no significant differences(P>0.05)were observed in feed intake, feed conversion ratio and survivability. Carcass yields, including breast, thigh, drumstick, wing, neck, liver, heart, and spleen, were not significantly affected by the different monochromatic lighting sources (P>0.05). However, significant differences(P˂0.05)in the weights of the back and proventriculus were observed between the white LED group and the other treatment groups. These results suggest that LED lighting could serve as a better alternative to incandescent bulbs in broiler houses, with the potential to enhance broiler performance and carcass yield.

Effects of Low-Dose Kinetin, 2,4-D and Monochromatic Light Conditions on Flavonoid Content in Callus Culture of Dioscorea esculenta

The callus culture of Dioscorea esculenta is a potential strategy to produce efficacious bioactive compounds in multiplied production. It can be carried out by applying plant growth regulators (PGR) and environmental modification, including light-emitting diodes (LEDs) exposure. This study aims to investigate the impact of PGR and the stimulatory effect of LEDs on flavonoid profiles in D. esculenta callus culture. The study was conducted using combination variations of 2,4-D (0.5 and 1 ppm), kinetin (0.5 and 1 ppm), and LEDs stimulatory conditions (light and dark). The results showed that flavonoids are the dominant compounds found in lesser yam cultures, which reached more than 78 % in all treatments-specifically, adding 0.5 ppm kinetin and 0.5 ppm 2,4-D to D. esculenta callus cultures significantly increased flavonoids production compared to single PGR treatment. This shows there is a synergistic activity induced by 2,4-D and kinetin. Furthermore, monochromatic light exposure also significantly affects flavonoid production. Analysis of 5 main flavonoids, isoflavones, flavanones, kaempferols, quercetin, and epigallocatechin, proved that monochromatic light significantly increased flavonoids production compared to callus cultures were kept in a growth room under 24 °C temperature in the dark condition. This study confirmed that equally combining 0.5 ppm of 2,4-D and 0.5 ppm of kinetin under monochromatic LEDs increases flavonoid production in D. esculenta callus cultures. Further research must be conducted to describe how the bioactive compound synthesis signaling pathway involving PGR and monochromatic LEDs improves plant quality in the pharmaceuticals’ role. HIGHLIGHTS Kinetin and 2,4-D at the same concentration of 0.5 ppm is an optimal combination to increase secondary metabolite production in esculenta callus culture Combining kinetin and 2,4-D at low concentrations significantly increased flavonoids, especially kaempferol, isoflavone, quercetin, flavanone, and epigallocatechin in esculenta callus culture Light condition significantly affects the production of flavonoids, especially kaempferol, isoflavone, quercetin, flavanone, and epigallocatechin There is evidence that kinetin and 2,4-D under light conditions work in a synergic effect on the biosynthesis of secondary metabolite compounds in esculenta callus cultures GRAPHICAL ABSTRACT

Indoor Self-Powered Perovskite Optoelectronics with Ultraflexible Monochromatic Light Source.

Self-powered skin optoelectronics fabricated on ultrathin polymer films is emerging as one of the most promising components for the next-generation Internet of Things (IoT) technology. However, a longstanding challenge is the device underperformance owing to the low process temperature of polymer substrates. In addition, broadband electroluminescence (EL) based on organic or polymer semiconductors inevitably suffers from periodic spectral distortion due to Fabry-Pérot (FP) interference upon substrate bending, preventing advanced applications. Here, ultraflexible skin optoelectronics integrating high-performance solar cells and monochromatic light-emitting diodes using solution-processed perovskite semiconductors is presented. n-i-p perovskite solar cells and perovskite nanocrystal light-emitting diodes (PNC-LEDs), with power-conversion and current efficiencies of 18.2% and 15.2cd A-1 , respectively, are demonstrated on ultrathin polymer substrates with high thermal stability, which is a record-high efficiency for ultraflexible perovskite solar cell. The narrowband EL with a full width at half-maximum of 23nm successfully eliminates FP interference, yielding bending-insensitive spectra even under 50% of mechanical compression. Photo-plethysmography using the skin optoelectronic device demonstrates a signal selectivity of 98.2% at 87bpm pulse. The results presented here pave the way to inexpensive and high-performance ultrathin optoelectronics for self-powered applications such as wearable displays and indoor IoT sensors.

Highly Monochromatic Ultraviolet LED Based on the SnO2 Microwire Heterojunction Beyond Dipole-Forbidden Band-Gap Transition.

SnO2 has been extensively applied in the fields of optoelectronic devices because of its large band gap, high exciton binding energy, and outstanding optical/electrical properties. However, its applications in ultraviolet light-emitting diodes (LEDs) are still hindered by the dipole-forbidden rule. Herein, the dipole-forbidden rule can be conquered by synthesizing Sb-incorporated SnO2 microwires (SnO2:Sb MWs), which are examined by ultraviolet photoluminescence emitting at 363.2 nm and a line width of 11.3 nm. Subsequently, a highly monochromatic ultraviolet light-emitting diode (LED) based on a SnO2:Sb MW heterojunction was constructed with a p-GaN film serving as the hole supplier. In the LED, the presence of a MgO intermediate layer can modulate carrier transport and recombination path, thus achieving band-edge optical transition in the SnO2:Sb MW. As the LED is modified using Ag nanowires, electrical properties, especially for the hole injection efficiency, were dramatically boosted, contributing significantly to the device high brightness. The LED emits at 365.9 nm and a line width of 12.4 nm. Therefore, we have realized a high-brightness and narrow-band ultraviolet LED with the shortest peak wavelength never seen in previously reported SnO2 LEDs. This work will promote the potential applications of low-dimensional SnO2 optoelectronic devices and provide an effective exemplification to overcome the dipole-forbidden rule in metal-oxide materials with "forbidden" energy gaps.

Hydrophobic Mn-Doped Solid-State Red-Emitting Carbon Nanodots with AIE Effect and Their Hydrogel Composites for Color-Changing Anticounterfeiting.

The aggregation-caused quenching has always limited the high concentration and solid-state applications of carbon nanodots. While the aggregation-induced emission effect, dominated by intramolecular motion, may be an effective means to solve this problem. Here, hydrophobic solid-state red-light carbon nanodots (M-CDs) with 95% yield are synthesized by a one-step hydrothermal method using 2,2'-dithiodibenzoic acid as the carbon source and manganese acetate as the dopant source. The disulfide bond of 2,2'-dithiodibenzoic acid serves as the symmetry center of molecular rotation and Mn catalyzes the synthesis of M-CDs, which promotes the formation of the central graphitic carbon structure. The M-CDs/agar hydrogel composites can achieve fluorescence transition behavior because of the special fluorescence transition properties of M-CDs. When this composite hydrogel is placed in water, water molecules contact with M-CDs through the network structure of the hydrogels, making the aggregated hydrogels of M-CDs fluorescence orange-red under 365nm excitation. While in dimethyl sulfoxide, water molecules in the hydrogels network are replaced and the M-CDs fluoresce blue when dispersed, providing a potential application in information encryption. In addition, high-performance monochromatic light-emitting diode (LED) devices are prepared by compounding M-CDs with epoxy resin and coating them on 365nm LED chips.

Evaluation of Growth and Production of High-Value-Added Metabolites in Scenedesmus quadricauda and Chlorella vulgaris Grown on Crude Glycerol under Heterotrophic and Mixotrophic Conditions Using Monochromatic Light-Emitting Diodes (LEDs).

This study aimed to examine the impact of crude glycerol as the main carbon source on the growth, cell morphology, and production of high-value-added metabolites of two microalgal species, namely Chlorella vulgaris and Scenedesmus quadricauda, under heterotrophic and mixotrophic conditions, using monochromatic illumination from light-emitting diodes (LEDs) emitting blue, red, yellow, and white (control) light. The findings indicated that both microalgae strains exhibited higher biomass yield on the mixotrophic growth system when compared to the heterotrophic one, while S. quadricauda generally performed better than C. vulgaris. In mixotrophic mode, the use of different monochromatic illumination affected biomass production differently on both strains. In S. quadricauda, growth rate was higher under red light (μmax = 0.89 d-1), while the highest biomass concentration and yield per gram of consumed glycerol were achieved under yellow light, reaching 1.86 g/L and Yx/s = 0.18, respectively. On the other hand, C. vulgaris demonstrated a higher growth rate on blue light (μmax = 0.45 d-1) and a higher biomass production on white (control) lighting (1.34 g/L). Regarding the production of metabolites, higher yields were achieved during mixotrophic mode in both strains. In C. vulgaris, the highest lipid (26.5% of dry cell weight), protein (63%), and carbohydrate (20.3%) contents were obtained under blue, red, and yellow light, respectively, thus indicating that different light wavelengths probably activate different metabolic pathways. Similar results were obtained for S. quadricauda with red light leading to higher lipid content, while white lighting caused higher production of proteins and carbohydrates. Overall, the study demonstrated the potential of utilizing crude glycerol as a carbon source for the growth and metabolite production of microalgae and, furthermore, revealed that the strains' behavior varied depending on lighting conditions.

Solvent-free synthesis of oil-soluble fluorescent carbon dots for bright photoluminescent and electroluminescent light-emitting diodes

Fluorescent carbon dots (CDs) have attracted great attention in multidisciplinary fields due to their distinctive advantages of tunable emission, low toxicity and abundant raw materials. However, it is still a big challenge to effectively applicate these CDs in electroluminescent light-emitting diodes (LEDs) due to their poor oil solubility and easy aggregation-induced quenching. Herein, an oil-soluble fluorescent CDs is designed and synthesized using triphenylamine and 4-iodophenyldiphenylamine as precursors through a solvent-free reaction. The obtained CDs (TPA-CDs) display an emission peak at 551 nm with good oil-solubility in different organic solvents. Therefore, TPA-CDs can be used as the host material of emission layer to prepare monochromatic electroluminescent LEDs with a maximum luminance of 227 cd·m−2 and as guest material in PVK to demonstrate white light electroluminescent LED with a maximum luminance of 1503 cd·m−2. This CDs can also be mixed well with oil soluble resin to easily assemble photoluminescent devices with a high luminous efficiency of 17.1 lm·W−1. This is the first example that solvent-free synthesized CDs are used for both photoluminescent and electroluminescent devices.

Bridging the Green Gap: Monochromatic InP-Based Quantum-Dot-on-Chip LEDs with over 50% Color Conversion Efficiency.

Solid-state light-emitting diodes (LEDs) emit nearly monochromatic light, yet seamless tuning of emission color throughout the visible region remains elusive. Color-converting powder phosphors are therefore used for making LEDs with a bespoke emission spectrum, yet broad emission lines and low absorption coefficients compromise the formation of small-footprint monochromatic LEDs. Color conversion by quantum dots (QDs) can address these issues, but high-performance monochromatic LEDs made using QDs free of restricted, hazardous elements remain to be demonstrated. Here, we show green, amber, and red LEDs formed using InP-based QDs as on-chip color convertor for blue LEDs. Implementing QDs with near-unity photoluminescence efficiency yields a color conversion efficiency over 50% with little intensity roll-off and nearly complete blue light rejection. Moreover, as the conversion efficiency is mostly limited by package losses, we conclude that on-chip color conversion using InP-based QDs can provide spectrum-on-demand LEDs, including monochromatic LEDs that bridge the green gap.

Effects of Monochromatic Light on Growth and Quality of Pistacia vera L.

Light-emitting diodes (LEDs) are popular as a light source for in vitro plants because they save energy and allow the morphology of the plant to be altered. The purpose of this study was to show that switching from classical fluorescent light (FL) to LED light can have both beneficial and adverse effects. Pistacia vera plantlets were exposed to FL, monochromatic Blue LED light (B), monochromatic Red LED light (R), and a 1:1 mixture of both B and R (BR). R increased the total weight, shoot length, number of shoots ≥ 1 cm, and proliferation. It also reduced hyperhydricity (HH), but also dramatically increased shoot tip necrosis (STN) and leaf necrosis (LN). B cured plants of HH and STN, but hardly enabled proliferation. It did not solve the problem of LN, but the plants were high in total chlorophyll and carotenoids. BR reduced HH but enabled limited proliferation, high STN, and LN. All three LED treatments reduced HH compared to FL. B induced both high total phenolic and flavonoid content and high DPPH-scavenging activity. These results show that switching from FL to LED can have a significant positive or negative effect on proliferation and quality. This suggests that finding an optimal lighting regimen will take a lot of trial and error.

Modulation of VOC fingerprint and alteration of physiological responses after supplemental LED light in green- and red-leafed sweet basil (Ocimum basilicum L.)

Narrowband green (G), blue (B), red (R), and polychromatic (W ‒ R:G:B, 1:1:1) lights were supplemented (250 µmol photon m‒2 s‒1; 5 h d−1; 21 d) to ambient light with Light Emitting Diodes (LED) in green- (‘Tigullio’; TI) and red-leafed (‘Red Rubin’; RR) sweet basil (Ocimum basilicum L.) plants. The aim of this work was to evaluate LED-triggered variations in biometric and morpho-anatomical traits, photosynthesis and secondary metabolite production to ‘photomodulate’ plant performance via monochromatic LED light supplementation.In both the cultivars, light supplementation did not alter plant biomass production compared to controls and at the amplitude applied therein any LED supplementation resulted in oxidative stress, as evidenced by slight changes in chlorophyll fluorescence parameters and H2O2 staining in leaves. Conversely, monochromatic LEDs selectively modulate metabolomics profile in both green- and red-leafed basil; e.g., B lights increased polyphenol content in TI, whilst G light resulted effective in reducing cyanidin-3-coumaroil-glucoside one of the prevalent acylated anthocyanin of RR. Volatilome profile unveiled profound waveband-dependent alterations though consistently eugenol, characterised by a clove flavor, and also considered one of the major toxic compounds in sweet basil, decreased with all the LED treatments, making green-leafed basil a more pleasant and safer product.Our dataset offers the clear evidence that monochromatic LED light supplementation represents a valid tool to modulate the accumulation of targeted secondary metabolites in planta.

Efficient All‐Perovskite White Light‐Emitting Diodes Made of In Situ Grown Perovskite‐Mesoporous Silica Nanocomposites

AbstractMetal halide perovskite quantum dots (QDs) have emerged as potential materials for high brightness, wide color gamut, and cost‐effective backlight emission due to their high photoluminescence quantum yields, narrow emission linewidths, and tunable bandgaps. Herein, CsPbX3/SBA‐15 nanocomposites are prepared with outstanding optical properties and high stability through an in situ growth strategy using mesoporous silica particles. According to finite‐difference time‐domain simulations, the mesoporous structure provides a strong waveguide effect on perovskite QDs and the uniform dispersion suppresses reabsorption losses, improving the overall photoconversion efficiency of perovskite QDs. The as‐fabricated perovskite monochromatic light‐emitting diode (LED) has a maximum luminous efficiency of 183 lm W−1, which is the highest for monochromatic perovskite LEDs reported to date. A further benefit of this work is that the white devices, which combine the green and red perovskite nanocomposites with commercial blue LED, exhibit a high luminous efficiency of 116 lm W−1 and a wide color gamut (125% for NTSC and 94% for Rec. 2020) with coordinates of (0.33,0.31).

Monochromatic LED-based spectrally tunable light source for chromatic confocal sensors

Prior art emission spectra of light sources utilized in chromatic confocal sensors share two disadvantages: the uneven spectral power distribution (SPD) and the fixed distribution characteristic. Consequently, the detected peak signal intensity is regulated by the SPD properties of the light source and the spectrum transmittance characteristics of the dispersive lens. To achieve this, 18 types of monochromatic light-emitting diodes (LEDs) with different peak wavelengths were selected to create a wide-spectrum light source with a tunable SPD. The SPD characteristics of the light source can be modified by adjusting the luminous intensity of each LED. The tungsten halogen lamp, the “white” LED, and the designed light source were selected as the light sources for the chromatic confocal measurement system, respectively. Comparing the peak signals obtained under various light sources. The experimental results show that, in the range of 400 to 700 nm, the peak signal intensity extreme value ratio measured with the designed light source is 1.81:1, and the normalized light intensity standard deviation is 0.118. The corresponding light intensity extreme value ratio of halogen tungsten lamp and white LED is 23.3:1, 300:1, and the normalized light intensity standard deviation is 0.302, 0.228. With the help of the designed light source, a group of wave crest signals with uniform light intensity distribution can be obtained. This can reduce the influence of the SPD characteristics of the light source itself and the transmissivity characteristics of the dispersive objective lens on the measured signal, and ensure the accuracy of spectral detection.

The Combination of Monochromatic LEDs and Elicitation with Stressors Enhances the Accumulation of Glucosinolates in Mustard Sprouts with Species-Dependency.

This work studies the enhancement of glucosinolates (GSLs) in mustard sprouts as health promoters. Sprouts of Sinapis alba, Brassica nigra, and B. carinata were grown under broad-spectrum, monochromatic blue or red light-emitting diode (LED) lamps, irrigated with 0-100 mM sodium chloride (NaCl), and sprayed with 0-250 µM methyl jasmonate (MeJA) as elicitor. The use of LEDs did not result in increased sprout biomass in any case. The effect of the applied treatments on the GSLs depended on the species and were restricted to Brassica spp. The red LEDs produced an overall increase in GSLs over 500% in B. carinata (from 12 to 81 mg 100 g-1 F.W.), compared to the white broad-spectrum lights, although the highest increase in content was obtained in treated sprouts with 250 µM MeJA (104 an 105 mg 101 g-1 F.W., under the red and blue LEDs, respectively). The combination of blue LEDs, 100 mM NaCl, and 250 µM MeJA enhanced the levels of GLSs in B. nigra to the maximum (81 mg 100 g-1 F.W.). Overall, these results indicate that by modifying the growing conditions for a given sprout, enhancement in the accumulation of GSLs as health promoters is possible. The use of these treatments is a sustainable alternative to genetic modification when looking for bioactive-enriched foods, delivering natural plant foods rich in bioactive ingredients (e.g., glucosinolates). Nevertheless, the response to the treatments varies among species, indicating that treatments will require adjustment across sprouts. Further research continues with producing cruciferous sprouts to obtain GSL-enriched formulas for further studying the effects of their bioavailability and bioactivity on health-promotion.

Influence of light quality and some growth regulators in inducing the production of Podophyllotoxin, a bioactive compound against cancer, in adventitious roots formed in the leaves of Hyptis suaveolens

Podophyllotoxin (PTOX) is an aryltetraline lignan used to treat skin lesions, such as warts, human papilloma virus, and genital infections. Hyptis suaveolens has PTOX in its roots and the culture of its plant tissues in vitro has been increasingly used to produce rare and high-quality medicinal compounds. Adventitious roots are an attractive source of phytochemicals due to their genetic and biosynthetic stability. Thus, the aim of the present study is to investigate adventitious roots’ induction in leaves and nodal segments under different light qualities and auxins in H. suaveolens. Adventitious roots have only emerged in H. suaveolens leaves grown in semi-solid MS medium, in the absence of light and under red light-emitting diode (LED). Root dry weight values recorded for these treatments were statistically equal to each other, i.e., 21.84 and 29.81 mg, respectively. PTOX quantification was performed in the dark (10.72 µg g−1) and under red LED (9.93 µg g−1). Indole-3-butyric acid (IBA) and naphthaleneacetic acid (NAA) (0.5, 1.0 and 2.0 mg L−1) concentrations induced adventitious roots’ formation in leaves of plants belonging to this species. Explant supplemented with 2.0 mg L−1 NAA led to higher root dry weight (45.53 mg) in leaves. However, the 1.0 mg L−1 IBA treatment produced more PTOX (9.96 µg g−1 root). Nodal segments of H. suaveolens, IBA and NAA concentrations (0.5, 1.0 and 2.0 mg L−1) also induced adventitious roots’ formation. The treatment with 0.5 mg L−1 IBA resulted in higher root dry weight (37.62 mg) in the nodal segment. However, 1 and 2 mg L−1 IBA resulted in lower root dry weight and higher PTOX (9.97 µg g−1 and 9.95 µg g−1). In conclusion, adventitious root formation and PTOX induction in H. suaveolens leaves grown in semi-solid MS medium only happen in plants grown in the dark and under monochromatic red LED light. Growth regulator NAA was the best element to induce adventitious roots’ emergence in leaves, whereas IBA was the best one for such a purpose in nodal segment. Growth regulator NAA can inhibit the synthesis of PTOX, but IBA induces this secondary compound.

7-M/130-Mbps LED-to-LED Underwater Wireless Optical Communication Based on Arrays of Series-Connected LEDs and a Coaxial Lens Group

In this paper, the arrays consist of series-connected monochromatic light-emitting diodes (LEDs) are proposed as the transmitter and receiver to implement an LED-to-LED underwater wireless optical communication (UWOC) system. An array of green LEDs is used as the transmitter to enhance the emitted optical power, and the high-frequency attenuation of the LEDs is compensated by a pre-equalization circuit. Red LEDs are connected in series, forming an array as the detector to extend the bandwidth of the receiver. Furthermore, a lens group for homogenizing and focusing the light spot is designed to increase optical power-density at the plane of detector, thus significantly enhancing the signal-to-noise ratio (SNR) of the captured signal. The proposed array with 3 series-connected red LEDs can increase the data rate by 22.2 % compared with a single red LED. An LED-to-LED UWOC system with a data rate of 130 Mbps over a 7-m underwater channel is realized with a BER lower than the forward error correction (FEC) threshold of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$3.8\times 10^{-3}$</tex-math></inline-formula> . To the best of our knowledge, this is the first time that the series-connected LEDs as the detector, combining with a lens group for homogenization and focusing, are applied in an LED-to-LED UWOC system, which achieve the highest rate-distance product among the reported LED detection-based wireless optical communication (WOC) systems.