Red Light Research Articles

Do seabirds dream of artificial lights? Understanding light preferences of Procellariiformes.

Seabirds, and particularly fledglings of burrow-nesting species, are greatly impacted by light pollution. During their inaugural flights from colony to sea, fledglings become grounded after encountering artificial light. Such groundings, or fallout events, affect many fledglings each year, causing mass mortality events. To mitigate this light-induced mortality, rescue programmes have been implemented for decades at many locations worldwide. Despite the notoriety of fallouts and their conservation implications, the contributing behavioural and biological factors remain mostly unknown. How the mechanisms of light attraction and light avoidance interact and how they manifest in different groups (e.g. age, personality, populations) or light pollution levels remain open questions. We tested behavioural choices of Cory's shearwater Calonectris borealis fledglings, rescued after being grounded in urban areas, and choices of breeding adults for contrasting light sources. Fledglings and adults were exposed to one of three treatments in an experimental Y-maze set-up: white light versus no light, blue versus red light, and a control with no light on each arm of the Y-maze. Both age groups clearly chose the no-light arms and the red light arm. This choice for longer wavelengths and darker environments, along with slower responses by fledglings, suggests that close range artificial light causes disorientation in seabirds. Our study helps to clarify the behavioural components of fallouts and provides further evidence on the disruptive effects of nocturnal artificial light on sensitive species like Procellariiformes.

BRAKE SHOE OVERHEAT INDICATION SYSTEM FOR HEAVY VEHICLES IN HILL STATIONS USING THERMOCOUPLE AND ARDUINO

This paper introduces a novel Brake Shoe Overheat Indication System designed to enhance the safety of heavy vehicles operating in hill stations. The system utilizes a combination of thermocouples and Arduino microcontroller to monitor and indicate brake shoe temperatures. A threshold temperature of 300 degrees Celsius is set, and the system provides visual indications through green and red lights along with an audible alarm, thereby preventing accidents due to brake overheating.

Optimization and characterization of doped photoactive layer P3HT: ICBA for organic optoelectronic applications

A doped bulk heterojunction P3HT: ICBA active layer was studied, aiming at the effects of chromium chloride (CrCl2) and Cobalt chloride (CoCl2) doping. The study involved linear optical and electrical characterization to analyze the impact of these additives on the photoactive layer's performance. The electrical properties of doped P3HT: ICBA revealed enhancements with CrCl2(5%wt), CrCl2(10%wt), CoCl2(5%wt), and CoCl2(5%wt) (5%wt) by 8.5x, 11x, 10x, and 14x respectively, compared to pure P3HT:ICBA under dark/light conditions. This improvement is attributed to enhanced internal charge generation. The study also examined the effect of thermal treatment on the active layer from 20 ºC to 65 ºC under dark/light conditions. Additionally, the doped photoactive layer samples were tested as optical sensors under white, green, and red light, with a slightly higher optical response under white light. The findings confirm that doping P3HT: ICBA with CoCl2 and CrCl2 improves optical and electrical responses due to better charge transfer and generation.

Blue and Red Light Downconversion Film Application Enhances Plant Photosynthetic Performance and Fruit Productivity of Rubus fruticosus L. var. Loch Ness

Light downconversion films can modulate incident light wavebands on crops, converting less utilised wavebands in an efficient way. In this experiment, red (conversion of green into red light wavebands), pink (conversion of UV and green into blue and red light but to a smaller degree than red film), and blue (conversion of UV into blue light) light downconversion films were used to cover blackberry plants throughout all phenological stages (from leaf emergence to fruit harvesting). The plants’ physiological and biometric performance, and fruit yield and quality were evaluated. Plants under blue and red films showed a higher net photosynthetic rate with +23.1% and +14.9%, respectively, and a higher stomatal conductance with +56.0% and +23.6%, respectively, with respect to controls, maintaining stability across stages, except for a decrease under the red film during fruiting. Both films significantly boosted the fruit yield, with the red film increasing the fruit number (+49.8%) and the blue film enhancing the berry shape (+10.7) and fresh weight (+36.6). Notably, no significant differences in nutraceutical quality, including total flavonoid and anthocyanin content, were observed. These findings suggest that light downconversion films, particularly red and blue films, can effectively enhance the photosynthetic performance and fruit production in blackberry plants without compromising the fruit quality. Future research on this topic should focus on balancing plant growth, fruit productivity, and enhancing fruit nutraceutical properties.

Photoelectrochemical sensor based on copper tetraamino phthalocyanine graphene oxide covalent compound for sensitive detection of cefazolin sodium

In the present research, a novel photoelectrochemical (PEC) sensor was built to detect cefazolin sodium. A copper tetraamino phthalocyanine (CuTAPc) covalently linked graphene oxide compound (CuTAPc-GO) was fabricated successfully by covalent bonding of CuTAPc with graphene oxide (GO). The novel PEC sensing platform was prepared using CuTAPc-GO as a photoelectric material. The prepared PEC sensor showed a higher PEC efficiency under red light. In the perfect conditions, the PEC sensor exhibited a linear correlation in detecting cefazolin sodium concentrations between 0.25 and 12.5μM, featuring a detection limit at 0.15μM. Furthermore, the manufacturing sensor was employed to detect cefazolin sodium in a real-world sample, demonstrating commendable sensitivity and stability. Thus, our study provides a new method for cefazolin sodium detection.

Engineering a photoenzyme to use red light

Engineering a photoenzyme to use red light

Model predictive control for unprotected left-turn based on sequential convex programming

In autonomous driving, an unprotected left turn is a highly challenging scenario. It refers to the situation where there is no dedicated traffic signal controlling the left turns; instead, left-turning vehicles rely on the same traffic signal as the through traffic. This presents a significant challenge, as left-turning vehicles may encounter oncoming traffic with high speeds and pedestrians crossing against red lights. To address this issue, we propose a Model Predictive Control (MPC) framework to predict high-quality future trajectories. In particular, we have adopted the infinity norm to describe the obstacle avoidance for rectangular vehicles. The high degree of non-convexity due to coupling terms in our model makes its optimization challenging. Our way to solve it is to employ Sequential Convex Optimization (SCP) to approximate the original non-convex problem near certain initial solutions. Our method performs well in the comparison with the widely used sampling-based planning methods.

Antibiotic evaluation of the nanocomposites IONs-MWCNTs-Pc and IONs-GO-Pc encapsulated in the biocompatible hydrogel poly(VCL-co-PEGDA) based on photodynamic effect

BackgroundThe rise of drug-resistant bacteria, including Staphylococcus aureus and Escherichia coli, presents a significant healthcare challenge. This study focuses on the development of two novel nanocomposites IONs-MWCNTs-Pc and IONs-GO-Pc encapsulated within a biocompatible poly(VCL-co-PEGDA) hydrogel. These composites are designed for use in photodynamic therapy and evaluated for their antimicrobial efficacy against resistant pathogens. ResultsThe synthesized nanocomposites, when irradiated with red light at 630 nm, showed significant antimicrobial activity, resulting in a marked reduction in the viability of S. aureus ATCC 27543, S. aureus ATCC 33591, and E. coli ATCC 971182. Photodynamic studies demonstrated that the IONs-GO-Pc nanocomposite was more efficient in generating singlet oxygen compared to IONs-MWCNTs-Pc, which correlated with its superior antimicrobial performance. Structural and chemical characterization confirmed the successful incorporation of nanomaterials and photosensitizers, enhancing the photodynamic effect. ConclusionsThe study demonstrates that both IONs-MWCNTs-Pc and IONs-GO-Pc nanocomposites show promise as alternative treatments for infections caused by antibiotic-resistant bacteria, with the GO-based composite showing higher photodynamic therapy efficacy. These findings suggest that such nanocomposites could play a pivotal role in advancing antimicrobial strategies against resistant pathogens.

Low-energy red light-emitting diode irradiation enhances osteogenic differentiation of periodontal ligament stem cells by regulating miR-146a-5p.

The study aimed to investigate the role of miR-146a-5p in osteogenesis of hPDLSCs irradiated with low-energy red LEDs. After irradiation with 5 J/cm2 red LED, miR-146a-5p expression was detected by real-time quantitative polymerase chain reaction (RT-qPCR), and osteogenic markers expression was determined by RT-qPCR and Western blotting. Alkaline phosphatase (ALP) activity was assessed by ALP staining, and mineralization was assessed by Alizarin Red staining, respectively. Lentiviral vectors were designed to regulate miR-146a-5p expression. Dual-luciferase reporter assay was performed to confirm the targeted relationship between miR-146a-5p and MAPK1. Short hairpin RNA (shRNA) was used to regulate MAPK1 expression. RT-qPCR and western blotting revealed that 5 J/cm2 irradiation elevated the levels of the osteogenic markers osterix (OSX) and bone sialoprotein (BSP) in hPDLSCs. miR-146a-5p is downregulated in hPDLSCs under the low-energy red LED light irradiation. miR-146a-5p underexpression markedly promoted the osteogenic potential of hPDLSCs. miR-146a-5p targeted MAPK1. 5 J/cm2 red LED irradiation rescued the inhibitory effects of upregulated miR-146a-5p on osteogenic differentiation, and the positive influence of red LED irradiation could be reversed by downregulated MAPK1. These findings confirm that miR-146a-5p is involved in the effect of LED irradiation on the osteogenic differentiation of hPDLSCs by targeting MAPK1. Red LED irradiation may be a potential clinical adjunct therapy for periodontal regeneration.

Differences in drivers’ risk behaviour behind the wheel in relation to road risk perception: Insights from a study on a group of Polish car drivers

Numerous risky driving behaviours are considered the main causes of road accidents. Meanwhile, a number of studies conducted so far indicate that perceiving a higher risk in a certain behaviour is associated with a lower tendency to engage in that behaviour. Accordingly, the aim of this study was to examine whether there are differences in specific types of risky behaviours behind the wheel in relation to drivers’ perceptions of road risk. The Road Traffic Behaviour Questionnaires KZD and KZD-P were used to evaluate, respectively, different risky behaviours and risk perceptions in road traffic. Two groups of Polish car drivers with similar average KZD scores but significantly different KZD-P scores, i.e., higher vs. lower, were compared. The profiles of the answers were statistically analysed. It was found that drivers with a lower risk perception were far more likely to engage in those behaviours that are the most commonly reported and directly endanger road safety, e.g., speeding and running a red light. Simultaneously, there were several unsafe driving behaviours, e.g., driving without a seatbelt or speaking on a mobile phone while driving, which were taken regardless of risk perception, i.e., even by the drivers who were aware of their riskiness. The results suggest that risk perception is a significant factor in preventing not all types but only selected hazardous behaviours in road traffic. The significance of the findings for traffic safety as well as ideas for further research in this area are discussed.

Metal Ion‐Endows Orange‐Red Light Fluorogenicity of an Imine‐Linkage Probe Embracing Simple Electron Donor‐Acceptor Units

AbstractSelectively tracking and quantifying Al3+ ions is a significant concern to the scientific communities. In the present article, an imine‐linkage electron donor‐acceptor system, DSAN, (E)‐5‐(diethylamino)‐2‐(((2‐hydroxy‐4‐nitrophenyl)imino)methyl)phenol has been introduced which shows Al3+ ions endows red light fluorogenicity which could be utilized for sequential and detection of Al3+ ions and picric acid (PA) in both solid and liquid phases. Upon addition of Al3+ ions into the DSAN solution, an orange‐red fluorescence is noticed at 604 nm caused by the formation of Al3+ ions chelated DSAN complex having detection and quantification limit 0.2 μM and 0.62 μM respectively in dimethylformamide (DMF) medium. The complex formation is found to be a 1 : 1 stoichiometric ratio as evident from Job's plot analysis. Also, the binding affinity value is found to be 3.24×104 M−1 demonstrating a high affinity of DSAN towards Al3+ ions. This orange‐red fluorescence of Al3+ ions chelated DSAN complex solution is quenched due to the introduction of PA. A super handy paper‐strips‐based detection tool also been fabricated utilizing DSAN which could be employed to track trace amounts of Al3+ ions in the solid state. The mechanism involved in the detection of Al3+ ions is elucidated by density functional theoretical analysis.

Luminescence, temperature sensing and Judd-Ofelt analysis of Bi2Mo3O12:Eu3+ phosphors and the application in latent fingerprint visualization

Eu3+-activated materials have garnered significant attention due to their outstanding optical characteristics. In this work, the sol–gel method was successfully used to prepare Bi2Mo3O12 phosphors doped with different amounts of Eu3+. The generated samples were identified as orthorhombic Bi2Mo3O12 with a scheelite-like structure by X-ray diffraction analysis of the crystal structure. The sample’s morphology and size were examined using scanning electron microscopy and transmmission electron microscopy, which revealed irregular block morphology and tens to hundreds nanometers scale dimension. From the analysis of the concentration-dependent luminescence intensity of Eu3+, it was confirmed that the exchange interaction was responsible for the quenching of 5D0 fluorescence of Eu3+. When excited at 374 nm, the phosphor emitted brilliant red light, with the highest emission occurring at 616 nm (5D0→7F2 transition), and the calculated color coordinates of the sample were (0.663, 0.336). By examining the temperature dependence of the emission spectra, the temperature sensing performance of the sample and the thermal quenching behavior of Eu3+ luminescence was explored. Furthermore, the optical transition property of Eu3+ was investigated by using the emission spectra and fluorescence lifetime within the context of Judd-Ofelt theory. Ultimately, latent fingerprint visualization of the sample on various object surfaces was studied, thanks to the intense luminescence and small particle size of the Bi2Mo3O12:Eu3+ phosphor. The results indicated that the sample can clearly display the different hierarchical features of fingerprint on different object surfaces.

Comparative investigation on carbon dots and chloride fluxes modified ZnAl2O4:Cr3+ nanophosphors for temperature sensing, cutting-edge forensic, anti-counterfeiting and w-LEDs applications

A novel Cr3+ doped ZnAl2O4 is synthesized by grafting carbon dots (CDs) and chloride fluxes (NaCl, KCl, NH4Cl) through the solid-state reaction method. Upon excitation at 530 nm wavelength, the Cr3+ ions in the ZAO NPs emit red light due to the influence of a strong crystal field. This red emission arises from the electric dipole 2Eg→4A2g of the Cr3+ ions. Among the chloride fluxes examined, NH4Cl had a significant impact on the PL intensity. Notably, when CDs are incorporated into the ZAO:7Cr3+/NH4Cl NPs, a remarkable increase of 17.25-folds in photoluminescence (PL) intensity is observed. This enhancement is substantially higher than that of CDs alone (11.23-folds) and NH4Cl alone (3.82-folds). The increased PL intensity is attributed to the Förster resonance energy transfer (FRET) mechanism. Furthermore, the addition of CDs (5 wt.%) enhanced the colour purity (CP) of ZAO:7Cr3+/NH4Cl NCs to 99.8%, achieving a high Internal quantum efficiency (IQE) of 93.4 %. Notably, the CDs (5 wt.%)@ZAO:7Cr3+/NH4Cl NCs maintained 92.43 % of their emission intensity even at 420 K, demonstrating exceptional thermal stability compared to ZAO:7Cr3+ NPs. Moreover, the NPs holds promise for optical thermometry, boasting a high relative sensitivity (Sr) of 6.74 × 10-2 %K-1 across a temperature range spanning from 300 to 480 K. Moreover, the latent fingerprints (LFPs) developed using CDs(5 wt.%)@ZAO:7Cr3+/NH4Cl NCs demonstrate remarkable selectivity and high contrast. Under UV irradiation, the structural features of LFPs at levels I–III are clearly visible. In addition, the strong red fluorescence emitted by CDs(5 wt.%)@ZAO:7Cr3+/NH4Cl NCs makes them suitable for applications in AC. CDs(5 wt.%)@ZAO:7Cr3+ NCs exhibit significant potential for w-LED fabrication, achieving a correlated colour temperature (CCT) of 5517 K, a CIE coordinate of (0.332, 0.331), and a high colour rendering index (CRI) of Ra = 94, outperforming ZAO:7Cr3+/NH4Cl NPs. Overall results clearly demonstrates that, CDs(5 wt.%)@ZAO:7Cr3+/NH4Cl NCs are effective for applications in optical thermometry, dactyloscopy, w-LEDs, and AC.

Microbial ecophysiology: Shedding light on the re-greening of chlorotic cyanobacteria

Cyanobacteria, key contributors to aquatic CO2 fixation, employ sophisticated acclimation strategies for survival under nitrogen-limited conditions. A new study reveals that red light influences the resuscitation of chlorotic cells through mechanisms involving the dark-operative protochlorophyllide reductase, which facilitates chlorophyll biosynthesis and re-greening under low-light conditions.

Visible light photodetectors based on the Bi2S3 flower-like 3D microrods with Schottky emission

This work presents a holistic approach to the fabrication of bismuth sulfide (Bi2S3) photodetectors, with a particular emphasis on material structure and morphology. Bi2S3 particles were synthesized using a microwave-assisted method, employing bismuth nitrate and L-cysteine as the sulfur source. Polyvinylpyrrolidone with two different molecular weights was used as a viscosity modifier to control the size and morphology of the particles. The as-synthesized powders were drop-casted onto interdigitated gold electrodes from an ethanol suspension and evaluated using different light sources. The results demonstrate that submicrometric material with a slightly higher aspect ratio generated a higher photocurrent under the same conditions, attributed to enhanced carrier transport due to the reduced rod diameter, photogating effects, and Schottky emission. Bi2S3 lamellar microrods exhibited responsivity of 0.93, 0.21, and 0.40 mA/W for red (628 nm), green (517 nm), and blue (468 nm) light, respectively. This resulted in detectivity in the range of 1.17–5.32 × 10¹⁰ Jones for the visible light spectrum.

Implementation of An Optical Gauss Meter Based on Ferrite and Hematite Ferrofluids

Three compositions Ni0.5Fe2.5O4, Ni0.7Fe2.3O4, and Fe2O3 were prepared by the co-precipitation method and checked by XDR, SEM, and VSM. The nanoparticles show a good match with the XRD standards. The particle sizes were 25, 32, and 18nm for the above compositions, respectively. The first composition showed the highest magnetization saturation. Suspensions containing the mentioned nanoparticles were prepared with two carrier fluids, distilled water, and dimethylsulphoxide (DMSO). A transmission to ultraviolet-visible light was tested and showed good transparency of more than 60 % in the red light region. The transparency to 623nm laser light under different magnetic fields of the six suspensions was tested. A simple device was fabricated to perform this test. The water suspension in water Ni0.5Fe2.5O4 has a larger variation in the transmitted power. The suspension of hematite shows no sensible change in the transmitted power. The magnetic properties of the nanoparticles and the dispersion property of the carrier fluid were behind the explanation of the suspension behaviors under the influence of the magnetic field.

Photon upconversion crystals doped bacterial cellulose composite films as recyclable photonic bioplastics

Biopolymers currently utilized as substitutes for synthetic polymers in photonics applications are predominantly confined to linear optical color responses. Herein we expand their applications in non-linear optics by integrating with triplet-triplet annihilation photon upconversion crystals. A photon upconverting biomaterial is prepared by cultivating Pd(II) meso-tetraphenyl tetrabenzoporphine: 9,10-diphenyl anthracene (sensitizer: annihilator) crystals on bacterial cellulose hydrogel that serves both as host and template for the crystallization of photon upconversion chromophores. Coating with gelatin improves the material’s optical transparency by adjusting the refractive indices. The prepared material shows an upconversion of 633 nm red light to 443 nm blue light, indicated by quadratic to linear dependence on excitation power density (non-linearly). Notably, components of this material are physically dis-assembled to retrieve 66 ± 1% of annihilator, at the end of life. Whereas, the residual clean biomass is subjected to biodegradation, showcasing the sustainability of the developed photonics material.

Differential Nitric Oxide Responses in Primary Cultured Keratinocytes and Fibroblasts to Visible and Near-Infrared Light.

NO is a crucial signaling molecule involved in skin health, the immune response, and the protection against environmental stressors. This study explores how different wavelengths of light, namely blue (455 nm), red (660 nm), and near infrared (NIR, 850 nm), affect nitric oxide (NO) production in skin cells. Primary keratinocytes and fibroblasts from three donors were exposed to these wavelengths, and NO production was quantified using a DAF-FM fluorescent probe. The results demonstrated that all three wavelengths stimulated NO release, with blue light showing the most pronounced effect. Specifically, blue light induced a 1.7-fold increase in NO in keratinocytes compared to red and NIR light and a 2.3-fold increase in fibroblasts compared to red light. Notably, fibroblasts exposed to NIR light produced 1.5 times more NO than those exposed to red light, while keratinocytes consistently responded more robustly across all wavelengths. In conclusion, blue light significantly boosts NO production in both keratinocytes and fibroblasts, making it the most effective wavelength. Red and NIR light, while less potent, also promote NO production and could serve as complementary therapeutic options, particularly for minimizing potential photoaging effects.

In Vivo Lifetime Imaging of the Internal O2 Dynamics in Corals with near-Infrared-Emitting Sensor Nanoparticles.

Mapping of O2 with luminescent sensors within intact animals is challenging due to attenuation of excitation and emission light caused by tissue absorption and scattering as well as interfering background fluorescence. Here we show the application of luminescent O2 sensor nanoparticles (∼50-70 nm) composed of the O2 indicator platinum(II) tetra(4-fluoro)phenyltetrabenzoporphyrin (PtTPTBPF) immobilized in poly(methyl methacrylate-co-methacrylic acid) (PMMA-MA). We injected the sensor nanoparticles into the gastrovascular system of intact colony fractions of reef-building tropical corals that harbor photosynthetic microalgae in their tissues. The sensor nanoparticles are excited by red LED light (617 nm) and emit in the near-infrared (780 nm), which enhances the transmission of excitation and emission light through biological materials. This enabled us to map the internal O2 concentration via time-domain luminescence lifetime imaging through the outer tissue layers across several coral polyps in flowing seawater. After injection, nanoparticles dispersed within the coral tissue for several hours. While luminescence intensity imaging showed some local aggregation of sensor particles, lifetime imaging showed a more homogeneous O2 distribution across a larger area of the coral colony. Local stimulation of symbiont photosynthesis in corals induced oxygenation of illuminated tissue areas and formation of lateral O2 gradients toward surrounding respiring tissues, which were dissipated rapidly after the onset of darkness. Such measurements are key to improving our understanding of how corals regulate their internal chemical microenvironment and metabolic activity, and how they are affected by environmental stress such as ocean warming, acidification, and deoxygenation. Our experimental approach can also be adapted for in vivo O2 imaging in other natural systems such as biofilms, plant and animal tissues, as well as in organoids and other cell constructs, where imaging internal O2 conditions are relevant and challenging due to high optical density and background fluorescence.

The efficacy of light-guiding microneedle patch for stimulating hair growth in androgenetic alopecia.

Androgenetic alopecia (AGA) is the most common form of hair loss characterized by miniaturization of hair follicles. Low-level light therapy (LLLT) and microneedling have shown potential in promoting hair regrowth. This study aims to evaluate the efficacy of an innovative light-emitting diode (LED) helmet cooperated with a novel light-guiding microneedle patch (LMNP) for stimulating hair growth in AGA. In this randomized clinical trial, 16 AGA patients received treatments using light-guiding microneedle patches (LMNPs) illuminated by a LED helmet equipped with green (522nm) and red (633nm) LEDs, delivering 50mW/cm2 power and 40J/cm2 energy. Treatments were applied weekly for 24weeks, targeting the frontal recession area. The right side of the scalp was treated with green light and the left with red light, each combined with a LMNP featuring 900µm height needles at a density of 105 per square centimeter. Hair density and diameter, along with patient and physician satisfaction scores, were assessed monthly. Both red and green LED treatments with LMNP, significantly enhanced hair density and diameter. Satisfaction scores, as reported by both physicians and participants, increased over time. Comparative analyses revealed no statistically significant differences in average satisfaction scores or in changes in hair density and diameter between the groups by the end of the study. Additionally, no serious adverse effects were reported, highlighting the safety of the treatments. The combined Light sources which is portable LED helmet and LMNPs shows promise as a non-invasive, effective treatment for AGA, with similar efficacy between red and green wavelengths.