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Light fidelity (LiFi) is a pioneering technology that incorporates high-speed wireless communication and illumination by using light-emitting diodes. Despite the fact that LiFi technology cannot replace radio frequency (RF) communication completely, it is preferable for indoor networks because of its high data rates, minimal RF interference, and low implementation costs. Although RF technology is known for its slow data transmission speeds, its access points can effectively cover a large area. Therefore, it is of utmost importance to integrate both RF and LiFi technologies to fully leverage the advantages of each, resulting in an enhanced system performance. A novel solution to integrate LiFi and RF access points is presented in this paper, which aims to improve users' data rates by setting access point selection criteria and the ability for users to switch to alternate access points. One of the crucial factors for selecting access points for users is the signal to noise and interference ratio (SINR). If a user's SINR falls below a specified threshold, they are allowed to switch immediately to alternative access points. This criterion ensures that the users experience minimal interference and noise, leading to improved data transmission rates. The performance of the dual system is analyzed using MATLAB Monte Carlo iterations, and the simulation results indicate that the proposed approach achieves a total sum rate of 2.2 × 10 9 bps, which is higher than the sum rates of individual LiFi and RF systems at 1.9 × 10 9 bps and 0.6 × 10 9 bps respectively. In conclusion, the proposed approach exhibits a substantial improvement in the total sum rate, increasing it by 72.2% from individual RF and by 13% from individual LiFi. This indicates that the combined system achieves significantly elevated data transmission rates, thereby increasing overall efficiency and providing better service to end-users. The results of the study demonstrate the effectiveness of the integration of LiFi and RF access points, which can have a significant impact on the future of wireless communication and networking. [ABSTRACT FROM AUTHOR]

Background: The duration of orthodontic treatment is often a significant deterrent for patients when considering conventional mechanics, which can be time-consuming. Photobiomodulation (PBM) utilizes visible red to near-infrared wavelengths of light frequencies to expedite orthodontic treatment time.Objective: To investigate the effect of three Light Emitting Diode (LED) frequencies and their heat generation on soft tissues in accelerating tooth movement through Finite Element Method (FEM) study.Material and Methods: In this FEM study, a three-dimensional FEM model of the skull of a male patient with mild to moderate crowding in the maxilla, and mandible. The dentitions were scanned using a Computed Tomography (CT). A static force of 70 gm on the anterior region of the maxilla and mandible was applied from the labial sides, and a second static analysis was carried out by using both a 70 gm of force and thermal load with three different frequencies of 740, 850, and 940 nm on the 1st and 3rd quadrants. The effect of LED application and heat generation was assessed on soft tissues in bringing faster orthodontic tooth movement.Results: Increased tooth movement with combined loading case in the 1st and 3rd quadrants when compared with the 2nd and 4th quadrants. The temperature distribution was higher at 940 nm followed by 740 & 850 nm of frequency. Conclusion: Faster movements were observed in the combined loading case in the 1st and 3rd quadrants compared to static loading in other quadrants. Heat generation was higher with 940 nm frequency followed by 740 and 850 nm.

Green and Red LEDs increase insulin production, but their comparative effects on pancreatic and beta cell development are unclear. Zebrafish embryos were divided into three groups: Control (n = 60), Green (G) (n = 60), and Red (R) (n = 60), then irradiated for three days (14 hours/day) with 0.5 W/cm2 G (λpeak = 520 nm, 180 mA) and R (λpeak = 660 nm, 210 mA). At the end of 72 h, pancreatic and beta cells, circadian rhythm, and oxidative stress gene were analyzed using RT‐PCR. Malondialdehyde, nitric oxide, superoxide dismutase, and glutathione levels were also evaluated. In the Red group, pancreatic area increased by ~97.13% compared to the Control group and by approximately ~62.16% compared to the G group (both p < 0.0001), and no significant difference in beta cell area (p = 0.964). G group insulin expression increased 2.31‐fold compared to R group (p < 0.0001). Red LED treatment increased MDA levels (p < 0.001), oxidative stress (fth1b, nqo1) (p < 0.0001), and per1b during the photophase (p < 0.0001) compared to G group. R LED treatment increases oxidative stress and disrupts circadian rhythm, leading to reduced insulin secretion. The positive effects of G LED treatment have potential for metabolic syndrome, diabetes, and pancreatic diseases. [ABSTRACT FROM AUTHOR]

Researchers worldwide have shown significant interest in doping glasses with rare-earth ions. This is particularly intriguing because rare-earth ions are extensively used to enhance the optical properties of host glasses, capitalizing on their unique spectroscopic characteristics due to optical transitions within the intra-4f shell. An in-depth review was conducted on various glass fabrication methods, such as sputtering, solgel, chemical vapor deposition, ion exchange, and direct melt quenching. The study emphasized the physical, optical, and photoluminescence properties of glasses made from glass formers co-doped with rareearth ions. Understanding the interrelationship between these properties is crucial for optimizing material performance across various technological applications. The research highlights the broad applicability of rare-earth-doped glasses in fields like white light emission, photonic devices, solid-state lasers, optical fiber communication, and biomedical applications. [ABSTRACT FROM AUTHOR]

Diacetyl (C4H6O2) is an important organic diketone that is widely used as flavoring agent and food additive. It is toxic when inhaled or exposed to high concentrations and may lead to chronic respiratory disease and neurodegenerative disorders. But, a viable optical detection method for rapid and quantitative estimation of diacetyl molecules in gas phase does not currently exist. Here, we report the design and development of a simple, compact and cost-effective robust optical technique exploiting incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) technique for high-sensitive selective detection and quantitative estimation of gas-phase diacetyl levels in real-time using a visible light emitting diode (LED) operating at 450 nm. The IBBCEAS method demonstrates an effective optical-path length of 4.5 km within an optical cavity (Finesse ~15706) composed of two high-reflective mirrors. A typical detection limit of ~190 parts-per-billion (ppb) for diacetyl was achieved with an optimum acquisition time of ~4 s at an optimal cavity pressure of 100 Torr. LED-based diacetyl sensor system was optimized, calibrated and demonstrated for trace detection of gaseous diacetyl at the ppb levels in various food products and liquor samples as a few representative applications, thus paving the way for development of future optical monitors. This work represents the development of a LED-based optical setup for the detection of diacetyl molecule in gas phase. [ABSTRACT FROM AUTHOR]

Background: Cognitive function, including moral decision-making abilities, can be impaired by sleep loss. Blue-enriched light interventions have been shown to ameliorate cognitive impairment during night work. This study investigated whether the quality of moral decision-making during simulated night work differed for night work in blue-enriched white light, compared to warm white light. Methods: Using a counterbalanced crossover design, three consecutive night shifts were performed in blue-enriched white light (7000K) and warm white light (2500K) provided by ceiling-mounted LED luminaires (photopic illuminance: ~200lx). At 03:30h on the second shift (i.e. twice) and at daytime (rested), the Defining Issues Test-2, assessing the activation of cognitive schemas depicting different levels of cognitive moral development, was administered. Data from 30 (10 males, average age 23.3±2.9 years) participants were analysed using linear mixed-effects models. Results: Activation of the post-conventional schema (P-score), that is, the most mature moral level, was significantly lower for night work in warm white light (EMM; estimated marginal mean = 44.3, 95% CI = 38.9-49.6; pholm=.007), but not blue-enriched white light (EMM = 47.5, 95% CI = 42.2-52.8), compared to daytime (EMM = 51.2, 95% CI = 45.9-56.5). Also, the P-score was reduced for night work overall (EMM = 45.9, 95% CI = 41.1-50.8; p=.008), that is, irrespective of light condition, compared to daytime. Neither activation of the maintaining norms schema (MN-score), that is, moderately developed moral level, nor activation of the personal interest schema (i.e. the lowest moral level) differed significantly between light conditions. The MN-score was however increased for night work overall (EMM = 26.8, 95% CI = 23.1-30.5; p=.033) compared to daytime (EMM = 23.1, 95% CI = 18.9-27.2). Conclusion: The results indicate that moral decisions during simulated night work in warm white light, but not blue-enriched white light, become less mature and principle-oriented, and more rule-based compared to daytime, hence blue-enriched white light may function as a moderator. Further studies are needed, and the findings should be tentatively considered. Trial registration: ClinicalTrials.gov (ID: NCT03203538) Registered: 26/06/2017; https://clinicaltrials.gov/study/NCT03203538 [ABSTRACT FROM AUTHOR]

Debate persists on light in controlled environment agriculture. To dissect the effects of conventionally used wavelengths on a crop and provide new information to this expanding food production sector, this study investigated the effects of monochromatic and combined red, blue, and amber light on lettuce growth with increasing light intensities (up to 1300 µmol·m−2·sec−1) for 18 days with a 16 h·d−1. Under amber light at PPFDs ranging from 500 to 700 µmol·m−2·sec−1, fresh mass displayed a 33.3% greater yield when compared to red light at the same PPFD. Suppressed growth was observed with either red or amber alone at high PPFD (>800 µmol·m−2·sec−1). Blue light was the least productive of the four treatments, yet lettuce plant growth was not suppressed at high intensities. No growth suppression was observed for lettuce plants grown under combined red-blue-amber light at high intensities, and these plants exhibited greater biomass yield than blue light alone. Varied degrees of pigmentation occurred under each light treatment, yet bleaching was only observed in plants grown under amber light alone at PPFD above 1000 µmol·m−2·sec−1. Findings present novel plant responses to high intensity light, setting precedence for future experiments aimed at expanding the use of LEDs in horticulture. [ABSTRACT FROM AUTHOR]

The present study investigated potential application of somatic embryogenesis (SE) for conservation of Kelussia odoratissima Mozaff. As the efficiency of SE greatly varies depending on the culture conditions including light, effects of five light spectrums including a fluorescent light and four types of light - emitting diode (LED) (red, blue, 3red-1blue, and 3blue:1red) for an exposure time of a month on the maturation of K. odoratissima were studied. To better understand the effect of light treatment on conversion of K. odoratissima cultures, two months after treatment, fresh and dry weight and metabolite contents were evaluated. Samples of the same age in-situ plant and air-dry plant were also considered for relative comparison. Study of developmental stage of K. odoratissima under in vitro conditions revealed that a combination of 3red:1blue LED provided the highest number of cotyledonary (mature) embryos per callus. Interestingly, 3red:1blue LED could significantly improve synchronization of somatic embryos. Hence, this light treatment was identified as the best treatment for the maturation of somatic embryos in K. odoratissima. In conversion stage, the highest fresh and dried weights were recorded for tissue culture plantlets grown under 3blue:1red and blue LED treatment. Phthalide content of fresh in-situ plant was significantly greater than other treatments. Interestingly, the phthalide content was significantly higher in leaves of tissue culture plantlets compared to air-dry in situ plants, which suggests tissue culture as an alternative technique for the production of bioactive compounds in K. odoratissima.Key message: LEDs can be effective in micropropagation of Kelussia odoratissima Mozaff, an endangered plant endemic to Iran. Our results could pave the way for the proliferation of plant in bioreactor systems. [ABSTRACT FROM AUTHOR]

As vegetables have been growing and space has gathered on the market, there is increasing demand for alternative light sources. This research aimed to evaluate the effects of colored LEDs on the germination and initial growth of lettuce plants, as well as their effects on the antioxidant system. Seeds were germinated in a chamber at 20°C under a 12-hour photoperiod. The light treatment in the first phase consisted of white and colored light-emitting diode (LED) lights (red-V + blue-A) in proportions of 100% V, 80% V + 20% A, 50% V + 50% A, and 80% A + 20% V. The first phase of the experiment consisted of a completely randomized design in a 2x4 factorial scheme (two light conditions and four seed lots) with four replications. The first count, germination, germination speed index (GSI), root length, shoot length, total seedling length, and shoot-to-root ratio were evaluated via image analysis. For the second phase of the experiment, the quantification of antioxidative enzyme activity (SOD, CAT, and APX) was performed to assess whether the light treatments (white LED light, colored LED light, and fluorescent light) caused photooxidative damage in the seedlings. Compared with white LED light, colored LED light improved plant germination and growth by promoting faster radicle protrusion, a greater GSI, a longer total seedling length, and a longer primary root length. The quantification of SOD, CAT, and APX activity indicated that the quality of light used in this work did not cause photooxidative stress in lettuce plants. [ABSTRACT FROM AUTHOR]

Background: The duration of orthodontic treatment is often a significant deterrent for patients when considering conventional mechanics, which can be time-consuming. Photobiomodulation (PBM) utilizes visible red to near-infrared wavelengths of light frequencies to expedite orthodontic treatment time. Objective: To investigate the effect of three Light Emitting Diode (LED) frequencies and their heat generation on soft tissues in accelerating tooth movement through Finite Element Method (FEM) study. Material and Methods: In this FEM study, a three-dimensional FEM model of the skull of a male patient with mild to moderate crowding in the maxilla, and mandible. The dentitions were scanned using a Computed Tomography (CT). A static force of 70 gm on the anterior region of the maxilla and mandible was applied from the labial sides, and a second static analysis was carried out by using both a 70 gm of force and thermal load with three different frequencies of 740, 850, and 940 nm on the 1st and 3rd quadrants. The effect of LED application and heat generation was assessed on soft tissues in bringing faster orthodontic tooth movement. Results: Increased tooth movement with combined loading case in the 1st and 3rd quadrants when compared with the 2nd and 4th quadrants. The temperature distribution was higher at 940 nm followed by 740 & 850 nm of frequency. Conclusion: Faster movements were observed in the combined loading case in the 1st and 3rd quadrants compared to static loading in other quadrants. Heat generation was higher with 940 nm frequency followed by 740 and 850 nm. [ABSTRACT FROM AUTHOR]

Underwater wireless optical communication (UOWC) systems have lately garnered a significant amount of attention for both academic purposes and trial applications. Although the idea is not new, the fact that seawater has a smaller window of absorption for blue-green light has reawakened interest in it, and it has grown an essential attraction because of its high bandwidth, it can cover a wide variety of underwater activities as compared to radio frequency and acoustic technologies. To monitor pollution, maintain oil pipelines, monitor climate change, conduct offshore investigations, and conduct oceanography research, the wireless transmission of information underwater technology is of importance to the military, industrial, and scientific organizations all around the world. The use of wavelengths of visible light to transmit secure data across point-to-point connections in underwater optical wireless communication (UOWC) compares well with the usage of free-space optical (FSO) communications. However, UWOC systems also have a huge amount of absorption and scattering introduced by the aquatic channels. Different from standard terrestrial free-space optical communication, many unique system design strategies have been investigated in recent years to solve these technological issues. This article presents a vision as well as various obstacles in the domain of underwater optical wireless communication, a detailed overview, and comparison of underwater communications techniques (UOWC) links, basic modulation technique techniques, and c pursuits on UWOC. [ABSTRACT FROM AUTHOR]

Recent advancements in dentistry have introduced new light-curing units such as 1-second and 5-second LED curing lights to orthodontics. We aimed to evaluate the shear bond strength and Adhesive Remnant Index (ARI) of stainless-steel orthodontic brackets cured with 1-second, and 5-second LED curing lights. Ninety human extracted upper premolars were selected based on the inclusion and exclusion criteria. The selected teeth were randomly divided into 2 groups - Group I and Group II. In Group I, the teeth were bonded with Standard pre-adjusted edgewise upper premolar brackets (Orthox, JJ Orthodontics) using Transbond XT and cured with Woodpecker iLED 1-second curing light. In Group II, the same brackets and composite were used to bond and light-cure with 5-seconds Woodpecker LED-D unit. The shear bond strength and the Adhesive Remnant Index (ARI) of brackets in both groups were evaluated. Student t-test was used for the statistical analysis of the data. In Group-I (1-second LED curing light), the shear bond strength was 6.62 MPa, whereas it was 10.32 MPa in group II (5-second LED curing light). A highly significant difference was observed in the shear bond strength between the groups. The ARI scores further revealed that the 5-second curing light resulted in a safer failure mode, with adhesive remaining mostly on the bracket. We found that the 5-second Woodpecker LED-D curing light demonstrated higher shear bond strength compared to the 1-second iLED curing light, although both sets of bond strength values are clinically acceptable.

Blue sticky traps contribute substantially to monitoring the western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae), in greenhouses. Although sticky traps can detect the initial presence of thrips reliably, an estimation of the actual thrips density in the crop by counting number of thrips on the traps is often not accurate. To overcome this issue, we compared blue sticky traps and newly developed sticky LED-enlightened traps in combination with the commercial thrips kairomone Lurem-TR under commercial growing conditions. Therefore, an experiment was conducted in cucumber, Cucumis sativus L. (Cucurbitaceae), crop stands in greenhouse cabins investigating the correlation between thrips caught on (LED) traps and the thrips density in the crop for an accurate and reliable thrips monitoring. Additionally, experiments aiming to understand underlying mechanisms of thrips orientation towards traps in different scenarios were conducted under controlled conditions. Results show that thrips catches on sticky LED enlightened coloured traps correlated strongly positive with number of thrips in the crop, especially at low thrips population densities. Adding Lurem to this trap type further improved accuracy of the correlation in the greenhouse cabin experiment. Moreover, LED traps with and without Lurem were more attractive towards thrips in small follow-up experiments compared to standard blue sticky traps. The results are discussed in the context of general orientation of thrips and its behaviour towards visual and olfactory cues when considering different scenarios. Our study shows the successful integration of blue LEDs into an existing trapping system and underlines the advantages compared with standard sticky plates. In conclusion, sticky LED enlightened coloured traps have a potential as an improved thrips monitoring device that might improve pest management decisions. [ABSTRACT FROM AUTHOR]

A recent study showed the potential of the DA Perten 7200 NIR Spectrometer in detecting chlorpyrifos-methyl pesticide residue in rough, brown, and milled rice. However, this instrument is still lab-based and generally suited for point-of-sale testing. To provide a field-deployable version of this technique, an existing light emitting diode (LED)-based instrument that provides discrete NIR wavelength illumination and reflectance spectra over the range of 850–1550 nm was tested. Spectra were collected from rough, brown, and milled rice at different pesticide concentrations and analyzed for quantitative and qualitative measurement using partial least squares regression (PLS) and discriminant analysis (DA). Simulations for two LED-based instruments were also evaluated using corresponding segments of spectra from the DA7200 to represent LED illumination. For the simulation of the existing LED-based instrument (LEDPrototype1) fitted with 850, 910, 940, 970, 1070, 1200, 1300, 1450, and 1550 nm LED wavelengths, resulting R2 ranged from 0.52 to 0.71, and the correct classification was 70.4% to 100%. The simulation of a second LED instrument (LEDPrototype2) fitted with 980, 1050, 1200, 1300, 1450, 1550, 1600, and 1650 nm LED wavelengths showed R2 of 0.59 to 0.82 and correct classifications of 66% to 100%. These LED wavelengths were selected based on the significant wavelength regions from the PLS regression coefficients of DA7200 and the commercial availability of LED wavelengths. Results showed that it is possible to use a multi-spectral LED-based instrument to detect varying levels of chlorpyrifos-methyl pesticide residue in rough, brown, and milled rice. [ABSTRACT FROM AUTHOR]

A waste heat recovery system with thermoelectric generation was constructed to convert waste heat into electrical energy for powering light emitting diodes (LED) car lamps and enhancing the efficient utilization of low-grade energy. The response characteristics of the waste heat recovery system during different stages of energy conversion and LED car lamp operation were examined with the constant temperature heating furnace to replicate the heat source. The variations in light output characteristics of LED car lamps independently driven by energy storage components were investigated in practical scenarios. The results show that the energy storage component can efficiently store and recover electric energy from waste heat, operate an LED car lamp independently and mitigate voltage fluctuations resulting from temperature changes. The energy density of lithium batteries is high with storing substantial electric energy. The fast cold start speeds can be realized with extended lighting duration when the LED car lamps are drived independently, but the charging time is longer. The cold start speeds of supercapacitors are sluggish with rapid charging and discharging rates, which is helpful to alleviate the driving voltage fluctuation of LED car lamp when the waste heat recovery system is activated briefly. [ABSTRACT FROM AUTHOR]

Recent advancements in dentistry have introduced new light-curing units such as 1-second and 5-second LED curing lights to orthodontics. We aimed to evaluate the shear bond strength and Adhesive Remnant Index (ARI) of stainless-steel orthodontic brackets cured with 1-second, and 5-second LED curing lights. Ninety human extracted upper premolars were selected based on the inclusion and exclusion criteria. The selected teeth were randomly divided into 2 groups - Group I and Group II. In Group I, the teeth were bonded with Standard pre-adjusted edgewise upper premolar brackets (Orthox, JJ Orthodontics) using Transbond XT and cured with Woodpecker iLED 1-second curing light. In Group II, the same brackets and composite were used to bond and light-cure with 5-seconds Woodpecker LED-D unit. The shear bond strength and the Adhesive Remnant Index (ARI) of brackets in both groups were evaluated. Student t-test was used for the statistical analysis of the data. In Group-I (1-second LED curing light), the shear bond strength was 6.62 MPa, whereas it was 10.32 MPa in group II (5-second LED curing light). A highly significant difference was observed in the shear bond strength between the groups. The ARI scores further revealed that the 5-second curing light resulted in a safer failure mode, with adhesive remaining mostly on the bracket. We found that the 5-second Woodpecker LED-D curing light demonstrated higher shear bond strength compared to the 1-second iLED curing light, although both sets of bond strength values are clinically acceptable. [ABSTRACT FROM AUTHOR]

Environment-friendly indium phosphide (InP)-based quantum dots (QDs) with efficient red-emitting properties are sufficiently needed to satisfy the requirement of burgeoning display and lighting technology. Currently, the syntheses of InP QDs using tris(trimethylsilyl)phosphine as the precursor are highly toxic and expensive. Herein, we successfully introduced gallium (Ga) ions into tris(dimethylamino)phosphine-based red InP cores through thermally-promoted cation exchange, and the obtained Ga-doped InP cores exhibited significantly increased photoluminescence quantum yields (PLQY) of up to 26%. The existence of Ga was directly confirmed by energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy, and the functions of Ga were systematically studied. After subsequent coating of Ga-doped InP cores with ZnSeS and ZnS shells, the resulting Ga-InP/ZnSeS/ZnS QDs achieved a high PLQY of 62% with an emission maximum at 640 nm. In contrast, without Ga-doping, the PLQY only attained 36% using the same synthetic approach. This indicated an approximate 1.7-fold increase in PLQY. The enhancement of photoluminescence was related to the Ga3+, as it not only passivated surface defects of InP cores but also reduced core-shell interface stress. The Ga-InP/ZnSeS/ZnS QDs exhibited good stability towards heat treatment and ultraviolet (UV) irradiation. Moreover, the red light-emitting diode (LED) based on Ga-InP/ZnSeS/ZnS QDs performed well in a wide injected current range of 2 to 200 mA, with a maximum power efficiency of 0.68 lm/W. This work showcases Ga-doping through cation exchange as a promising strategy for enhancing the efficiency of InP-based red emitters. [ABSTRACT FROM AUTHOR]

AbstractBackground Cognitive function, including moral decision-making abilities, can be impaired by sleep loss. Blue-enriched light interventions have been shown to ameliorate cognitive impairment during night work. This study investigated whether the quality of moral decision-making during simulated night work differed for night work in blue-enriched white light, compared to warm white light.Methods Using a counterbalanced crossover design, three consecutive night shifts were performed in blue-enriched white light (7000 K) and warm white light (2500 K) provided by ceiling-mounted LED luminaires (photopic illuminance: ∼200 lx). At 03:30 h on the second shift (i.e. twice) and at daytime (rested), the Defining Issues Test-2, assessing the activation of cognitive schemas depicting different levels of cognitive moral development, was administered. Data from 30 (10 males, average age 23.3 ± 2.9 years) participants were analysed using linear mixed-effects models.Results Activation of the post-conventional schema (P-score), that is, the most mature moral level, was significantly lower for night work in warm white light (EMM; estimated marginal mean = 44.3, 95% CI = 38.9–49.6; pholm=.007), but not blue-enriched white light (EMM = 47.5, 95% CI = 42.2–52.8), compared to daytime (EMM = 51.2, 95% CI = 45.9–56.5). Also, the P-score was reduced for night work overall (EMM = 45.9, 95% CI = 41.1–50.8; p=.008), that is, irrespective of light condition, compared to daytime. Neither activation of the maintaining norms schema (MN-score), that is, moderately developed moral level, nor activation of the personal interest schema (i.e. the lowest moral level) differed significantly between light conditions. The MN-score was however increased for night work overall (EMM = 26.8, 95% CI = 23.1–30.5; p=.033) compared to daytime (EMM = 23.1, 95% CI = 18.9–27.2).Conclusion The results indicate that moral decisions during simulated night work in warm white light, but not blue-enriched white light, become less mature and principle-oriented, and more rule-based compared to daytime, hence blue-enriched white light may function as a moderator. Further studies are needed, and the findings should be tentatively considered.Trial registration: ClinicalTrials.gov (ID: NCT03203538) Registered: 26/06/2017; https://clinicaltrials.gov/study/NCT03203538

Abstract Organic–inorganic hybrid light-emitting devices have garnered significant attention in the last few years due to their potential. These devices integrate the superior electron mobility of inorganic semiconductors with the remarkable optoelectronic characteristics of organic semiconductors. The inquiry focused on analyzing the optical and electrical properties of a light-emitting heterojunction that combines p-type GaN with organic materials (PEDOT, PSS, and PMMA). This heterojunction is an organic–inorganic hybrid. The procedure entailed utilizing a spin-coating technique to apply a layer of either poly(methyl methacrylate) (PMMA) or a mixture of PMMA and poly(3,4ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT: PSS) onto an indium tin oxide (ITO) substrate. Subsequently, different Nd:YAG laser pulses (200, 250, and 300 pulses) were used to administer a GaN inorganic layer onto the prepared organic layer using a pulsed laser deposition approach. Subsequently, the thermal evaporation technique was employed to deposit an aluminum electrode on the top of the organic and inorganic layers, while laser pulses were fine-tuned for optimal performance. The Hall effect investigation verifies the p-type conductivity of the GaN material. The electroluminescence studies confirmed the production of blue light by the GaN-based devices throughout a range of voltage situations, spanning from 45 to 72 V.

Perovskite quantum dots (PQDs) have shown great promise for use in photovoltaic devices, due to their ability to offer advantages such as tunability of visible light and efficient light emission. This study demonstrates the successful utilization of a triazine-based PO-T2T (2,4,6-Tris[3(diphenylphosphenyl)phenyl]-1,3,5-triazine; PO-T2T) as the electron transport layer (ETL) through an all-solution process. To improve the structural and optical characterization of CsPbBr3 and CsPbI3 QDs, three organic solvents, namely chlorobenzene, methyl acetate, and ethyl acetate, were selected to find an effective orthogonal solvent for PO-T2T. The all-solution processed devices incorporating PO-T2T and Methyl acetate (MeOAc) demonstrated impressive external quantum efficiencies of 5.57% for CsPbBr3 and 1.60% for CsPbI3 QDs. Notably, these devices also achieved the highest maximum luminance among all-solution processed PQDs-LEDs, with values of 33334 cd m–2 for CsPbBr3 and 224 cd m–2 for CsPbI3 QDs.

Abstract In this research, we introduce an advanced methodology for the calculation of bulk light sources tailored for free-form surface design, focusing on the principle of energy conservation. This method is especially relevant for the evolving needs of micro-LED packaging, highlighting its potential in this burgeoning field. Our work includes the development of an algorithm for creating freeform-designed chip-scale package (FDCSP) components. These components seamlessly integrate LEDs and lenses, underscoring our commitment to advancing free-form surface design in chip-level packaging. By adhering to the principle of energy conservation, our approach facilitates a meticulous comparison of simulation outcomes with predefined target functions. This enables the iterative correction of discrepancies, employing layering techniques to refine the design until the simulated results closely align with our goals, as demonstrated by an appropriate difference curve. The practical application of these simulations leads to the innovative design of FDCSP devices. Notably, these devices are not just suitable for traditional applications in backlight modules but are explicitly optimized for the emerging sector of micro-LED packaging. Our successful demonstration of these FDCSP devices within backlight modules represents a significant achievement. It underscores the effectiveness of our design strategy and its expansive potential to transform micro-LED packaging solutions. This research not only contributes to the theoretical understanding of energy conservation in lighting design but also paves the way for groundbreaking applications in micro-LED and backlight module technologies.

Photoacoustic imaging (PAI) is gaining attention for its non-invasive diagnostic capabilities. Traditionally, bulky and expensive laser systems have been used as excitation light sources in PAI, posing challenges for translation and remote applications. High-power light emitting diodes (LEDs) can be an alternative light source. However, the necessary driver circuitry has not been extensively studied for driving the nanoseconds pulsed LEDs. This study develops and demonstrate for the first time the full circuit, performance, optimization and operating procedures of a nanosecond pulsed current source (NSPCS) to drive a high-power, high-speed LED array for PAI. The NSPCS driver can deliver tunable pulsed LED currents between 0 and 20 A, pulse widths of 50–100 ns, and trigger pulse repetition rates up to 20 kHz, achieving a driver efficiency of 58.27%. It can drive an array of 37 high-power LEDs (850 nm wavelength) with an electrical-to-optical efficiency of 24.8%. Illumination with this LED array produced a photoacoustic signal (after 79 dB amplification with low-noise amplifier) of 3.92 V (peak-to-peak) and a signal-to-noise ratio of 79.36 dB. The NSPCS circuit has demonstrated effective generation of tunable high-current pulses for LED-based PAI applications.

The COVID-19 pandemic highlighted public awareness of airborne disease transmission in indoor settings and emphasized the need for reliable air disinfection technologies. This increased awareness will carry in the post-pandemic era along with the ever-emerging SARS-CoV variants, necessitating effective and well-defined protocols, methods, and devices for air disinfection. Ultraviolet (UV)-based air disinfection demonstrated promising results in inactivating viral bioaerosols. However, the reported data diversity on the required UVC doses has hindered determining the best UVC practices and led to confusion among the public and regulators. This article reviews available information on critical parameters influencing the efficacy of a UVC air disinfection system and, consequently, the required dose including the systems components as well as operational and environmental factors. There is a consensus in the literature that the interrelation of humidity and air temperature has a significant impact on the UVC susceptibility, which translate to changing the UVC efficacy of commercialized devices in indoor settings under varying conditions. Sampling and aerosolization techniques reported to have major influence on the result interpretation and it is recommended to use several sampling methods simultaneously to generate comparable and conclusive data. We also considered the safety concerns and the potential safe alternative of UVC, far-UVC. Finally, the gaps in each critical parameter and the future research needs of the field are represented. This paper is the first step to consolidating literature towards developing a standard validation protocol for UVC air disinfection devices which is determined as the one of the research needs.

Perovskite quantum dots (PQDs) have shown great promise for use in photovoltaic devices, due to their ability to offer advantages such as tunability of visible light and efficient light emission. This study demonstrates the successful utilization of a triazine-based PO-T2T (2,4,6-Tris[3(diphenylphosphenyl)phenyl]-1,3,5-triazine; PO-T2T) as the electron transport layer (ETL) through an all-solution process. To improve the structural and optical characterization of CsPbBr 3 and CsPbI 3 QDs, three organic solvents, namely chlorobenzene, methyl acetate, and ethyl acetate, were selected to find an effective orthogonal solvent for PO-T2T. The all-solution processed devices incorporating PO-T2T and Methyl acetate (MeOAc) demonstrated impressive external quantum efficiencies of 5.57% for CsPbBr 3 and 1.60% for CsPbI 3 QDs. Notably, these devices also achieved the highest maximum luminance among all-solution processed PQDs-LEDs, with values of 33334 cd m–2 for CsPbBr 3 and 224 cd m–2 for CsPbI 3 QDs. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid light-emitting devices have garnered significant attention in the last few years due to their potential. These devices integrate the superior electron mobility of inorganic semiconductors with the remarkable optoelectronic characteristics of organic semiconductors. The inquiry focused on analyzing the optical and electrical properties of a light-emitting heterojunction that combines p-type GaN with organic materials (PEDOT, PSS, and PMMA). This heterojunction is an organic–inorganic hybrid. The procedure entailed utilizing a spin-coating technique to apply a layer of either poly(methyl methacrylate) (PMMA) or a mixture of PMMA and poly(3,4ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT: PSS) onto an indium tin oxide (ITO) substrate. Subsequently, different Nd:YAG laser pulses (200, 250, and 300 pulses) were used to administer a GaN inorganic layer onto the prepared organic layer using a pulsed laser deposition approach. Subsequently, the thermal evaporation technique was employed to deposit an aluminum electrode on the top of the organic and inorganic layers, while laser pulses were fine-tuned for optimal performance. The Hall effect investigation verifies the p-type conductivity of the GaN material. The electroluminescence studies confirmed the production of blue light by the GaN-based devices throughout a range of voltage situations, spanning from 45 to 72 V. [ABSTRACT FROM AUTHOR]

In this research, we introduce an advanced methodology for the calculation of bulk light sources tailored for free-form surface design, focusing on the principle of energy conservation. This method is especially relevant for the evolving needs of micro-LED packaging, highlighting its potential in this burgeoning field. Our work includes the development of an algorithm for creating freeform-designed chip-scale package (FDCSP) components. These components seamlessly integrate LEDs and lenses, underscoring our commitment to advancing free-form surface design in chip-level packaging. By adhering to the principle of energy conservation, our approach facilitates a meticulous comparison of simulation outcomes with predefined target functions. This enables the iterative correction of discrepancies, employing layering techniques to refine the design until the simulated results closely align with our goals, as demonstrated by an appropriate difference curve. The practical application of these simulations leads to the innovative design of FDCSP devices. Notably, these devices are not just suitable for traditional applications in backlight modules but are explicitly optimized for the emerging sector of micro-LED packaging. Our successful demonstration of these FDCSP devices within backlight modules represents a significant achievement. It underscores the effectiveness of our design strategy and its expansive potential to transform micro-LED packaging solutions. This research not only contributes to the theoretical understanding of energy conservation in lighting design but also paves the way for groundbreaking applications in micro-LED and backlight module technologies. [ABSTRACT FROM AUTHOR]

Underwater video regulation is an insightful research field that can help engineers with bettering investigation on the lowered condition. Submerged video preparing has been utilized in a many fields, such as submerged infinitesimal location, landscape examining, mine identification, media transmission connections, and self-proficient lowered vehicles. Be that as it may, submerged video experiences solid assimilation, dissipating, shading contortion, and clamor from the manufactured light sources, causing video obscure, cloudiness, and a somewhat blue or greenish tone. In this way, the improvement can be separated into two techniques, submerged video de-preliminaries and underexposed video concealing remaking. Relentless in remote correspondence structures, for instance 3G, 4G, and so on, a coming crisis is endless deftly of the nonattendance of consistently Radio Frequency (RF) resources; this deterrent in moving speed cannot strengthen the improvement notable for high information speed. So the new innovation of Light-Fidelity (Li-Fi) came into picture. This innovation can be contrasted to that of Wi-Fi and offers points of interest like expanded available spectrum efficiency, effectiveness, security, low idleness and a lot higher speed. Communication is accomplished by exchanging light-emitting diode (LED) lights on and off at a speed higher than what is detectable to the human eye. This paper presents the explanation behind underexposed picture corruption and surveys the cutting-edge knowledge calculations like video reduce hazing algorithm. In this calculation, it uses two different de-hazing methods, simple Dark Channel Prior (DCP) and Approximate Dark Channel Prior (ADCP), to reduce haze in a video. [ABSTRACT FROM AUTHOR]

Energy reduction is a great challenge in road lighting applications. Replacing high-pressure sodium vapor (HPSV) with light-emitting diodes (LED) is a viable approach to reducing energy consumption. However, a total replacement can incur a significant capital cost. This study aims to investigate the effects on light distribution by replacing HPSV lamps with LED lamps in HPSV luminaires using Light Intensity Distribution (LID) curve measurement and Backlight, Uplight and Glare (BUG) rating evaluation to reduce the adoption costs. While LED lamps have high illumination rates, the structural differences from HPSV lamps can affect the LID curve and original lighting design. Therefore, it is crucial to study photometric dispersion after retrofitting light sources. Both lamps were installed into similar HPSV luminaires to assess photometric performance using goniophotometer measurements. The HPSV lamp outperforms the LED lamp in terms of luminous flux (11.13%) and light intensity (7.69%), whereas the LED lamp outperforms the HPSV lamp in terms of efficacy rating (68.67%) and wattage used (47.61%). The findings indicate that retrofit LED luminaires have an LOR of 46.77% lower than the HPSV luminaires. The light distribution pattern is maintained but reduced to 40 to 50% for the main usable light angles. The reduced performance is caused by the lamp structure, which occupies a large area inside the luminaire housing, obstructing proper light distribution. Although overall energy consumption is reduced, similar illumination levels cannot be maintained. These outcomes can assist authorities and manufacturers with alternative methods of reducing costs while maintaining lighting levels. [ABSTRACT FROM AUTHOR]

This state-of-the art review is designed to state the competence of fullerene nanostructures in optoelectronic devices. Fullerene molecules own valuable structural, electronic, optical, electrical, and physical properties to be employed in optoelectronics device sector. Especially, modification of fullerene nanostructures and nanocomposite formation led to high performance light emitting diodes, optical sensors, and photovoltaics systems. Combination of conjugated polymers/molecules with fullerene has found to further enhance performance efficacy towards these devices. In nanocomposite form, fullerene molecules have been known to develop conjugation with conducting polymers for better charge, hole, or electron transference leading to device performance assistances. Consequently, conjugated polymers like poly(3-hexylthiophene), poly(3,4-ethylenedioxythiophene), poly(3-hexylthiophene-2,5-diyl), polystyrene sulfonate, polycyclopenta-dithiophene-benzothiadiazole, poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene), 4,4′-bis[(p-trichlorosilylpropylphenyl)phenylamino] biphenyl, etc. reinforced with fullerene have been utilized. Polymers with grafted fullerenes such as [6,6]-phenyl C61-butyric acid methyl ester and [6,6]-phenyl-C61-butyric acid hexyl ester and reinforced fullerene have also been recognized. In addition, non-conducting polymers like poly(methyl methacrylate) nanocomposite with fullerene was exploited. Mostly, fullerene C60 and C70 have been preferred as nanofiller in optoelectronic assemblies. Effectiveness of fullerene nanomaterials has been observed for luminescent light emitting diodes, solar cells (bulk heterojunction/polymer/perovskite), and optical sensors (photo-/organic/bacterial sensing). Nevertheless, fullerene nanocomposite designs need to be comprehensively investigated for better device performance by overcoming underlying working mechanism, fabrication, and performance challenges in related fields.

Rubens Camargo Siqueira1,2 1Department of Retina, Rubens Siqueira Research Center, São José do Rio Preto, São Paulo, Brazil; 2Postgraduate Department, Faculty of Medicine of São José do Rio Preto (FAMERP), São José do Rio Preto, São Paulo, BrazilCorrespondence: Rubens Camargo Siqueira, Email siqueiraretina@gmail.comAbstract: Photobiomodulation (PBM) is a type of phototherapy that employs light-emitting diodes (LEDs) or low-power lasers to selectively administer specific wavelengths of visible light, ranging from 500 to 1000 nm, including near-infrared (NIR) wavelengths. LEDs are advantageous compared to lasers due to their ability to treat large areas at a lower cost, lack of tissue damage potential in humans, and reduced risk of eye-related accidents. The ophthalmology community has recently taken interest in PBM as a promising novel approach for managing various retinal conditions such as age-related macular degeneration, retinopathy of prematurity, retinitis pigmentosa, diabetic retinopathy, Leber’s hereditary optic neuropathy, amblyopia, methanol-induced retinal damage, and potentially others. This review critically assesses the existing body of research on PBM applications in the retina, focusing on elucidating the underlying mechanisms of action and evaluating the clinical outcomes associated with this therapeutic modality.Keywords: photobiomodulation, near-infrared, light emitting diode, age-related macular degeneration

Aluminium Gallium Nitride (AlGaN) based light emitting diodes (LED) are the enabling technology for compact emitters of deep ultraviolet (DUV) radiation and are in high demand for environmental and medical applications. The efficiency of recent DUV LEDs is in the range of a few percent providing some potential for improvement. Apart from the light extraction efficiency the hole injection into the active region presents a major obstacle towards more efficient DUV LEDs. In this work, we investigate the emission spectra of a mixed multi quantum well (MQW) DUV LED to attain details on the active region carrier transport that allow an improvement of the hole injection. Changing the position of the long wavelength marker quantum well yields characteristic emission spectra which have been modelled with a multi scale carrier transport and luminescence simulator. The numerical modelling enables the extraction of opaque carrier transport characteristics in AlGaN such as the hole mobility in the highly doped barriers of the MQW.

Numerical simulations of carrier transport in aluminium gallium nitride based ultraviolet light emitting diodes (UV-LED) are performed in order to understand injection efficiency for light sources in the deep ultraviolet. With our simulator, calibrated with experimental data from a 265 nm UV-LED, quantum efficiencies have been analyzed. The maximum internal quantum efficiency (IQE) of 30% consists of the product from radiative recombination efficiency (RRE) of 60% and carrier injection efficiency (CIE) of 50%. It is found that poor hole injection into the active region and a surplus of electrons limit both efficiencies, and leads to significant electron leakage into the p-side. This leakage is bias dependent, and has a minimum at maximum IQE. Further simulations show that distributed polarization doping (DPD) could improve carrier injection efficiency.

This paper extends previous work on liquid-crystal-display-based angle-of-arrival (AoA) estimation, initially performed for only a single light source (LS), by considering scenarios with multiple LSs. First, the system model is revisited to investigate parameters that influence detection of multiple LSs. Next, challenges such as separation of co-located LSs and ambiguities are investigated. It is identified that target separation gets increasingly challenging with decreasing distance between LSs, and AoA estimation developed for a single LS leads to ambiguities in scenarios with multiple LSs. These problems are solved by a novel angular separation algorithm and dedicated intensity measurements. Finally, two new experimental setups are introduced to investigate and model optical diffraction effects, and to verify theoretical derivations by measurement results.