Search Results (103)

In this paper, we propose a lightweight authentication and identification protocol based on different phosphorescent Strontium aluminate color labels. The excitation sources are pulsed UV LEDs emitting at 365 nm and 385 nm, causing different RGB-dependent time responses of the label that are measured using a smartphone recording at 30 FPS. The rise and decay time responses as measured by the red (R), green (G) and blue (B) pixels were separately analyzed and were found to follow a power law with individual parameters depending on the excitation wavelength, pulse duration and duty cycle, which serve as security features and are suitable for authentication purposes in IoT applications. Our solution uses simple cryptographic functions such as HMAC and XOR. We performed a security analysis of our protocol to prove its resistance to known attack vectors. The proposed scheme has minimal computation and communication costs and can be deployed on resource-constrained Internet of Things devices. Full article

Co²⁺-doped CsPbI₃ nanocrystals (NCs) (CsPbI₃:xCo, x = 0, 5, and 10 mol%) were synthesized in situ within a borosilicate glass matrix by the fusion method followed by controlled thermal treatment at 500 °C for 6–24 h. Transmission electron microscopy images showed quasi-spherical NCs with mean diameters of 4.9–7.1 nm. Energy-dispersive X-ray spectroscopy suggested cobalt incorporation within the nanocrystalline regions. X-ray diffraction patterns confirmed the exclusive stabilization of the cubic α-phase across all compositions, with systematic lattice contraction from a = 6.321 Å to a = 6.301 Å with increasing Co content, consistent with preferential B-site substitution of Pb²⁺ by Co²⁺. Transmittance measurements confirmed macroscopic optical transparency of all glass-NC composites after thermal treatment. The crystal field theory and Tanabe–Sugano analysis for d⁷ ions in tetrahedral (Td) symmetry yielded Δ = 5032 cm⁻¹ and B = 725 cm⁻¹ in the as-prepared state, evolving to Δ = 4428 cm⁻¹ and B = 805 cm⁻¹ after thermal treatment, confirming Td Co²⁺ coordination and significant metal–iodide covalency. CIE 1931 chromaticity analysis revealed tunable emission from deep-red coordinates to near-white-light regions, demonstrating potential for LED and single-material WLED phosphor applications. Long-term photoluminescence measurements demonstrated full preservation of α-phase excitonic emission after approximately 365 days under ambient conditions, establishing the robust phase stability of CsPbI₃:xCo NCs embedded in borosilicate glass. Full article

This study investigates a combined advanced oxidation process (AOP) utilizing UVA-LED irradiation (365 nm) for the degradation of sucralose (SUC), a complex artificial sweetener that poses a challenge for wastewater treatment due to its resistance to conventional methods. A sequential treatment strategy was employed. The initial step utilized UVA-activated persulfate (PS) at varying dosages (0.12–0.5 g/L) and UVA fluence rate (ranging from 20 to 100% of nominal output). The influence of natural water components (bicarbonate, chloride, sulfate, and nitrate) on PS activation was systematically analyzed. Notably, the substantial pH decrease during oxidation opened the possibility of replacing an amount of PS with the less expensive and more environmentally friendly hydrogen peroxide (H₂O₂) in the subsequent Fenton reaction. This second step employed a stoichiometric dosage of H₂O₂ (2.12 g/g COD) and varying Fe²⁺ concentrations (0.05–0.2 g/L), achieving a 95% overall mineralization within 60 min. The combined process incurred an approximate cost of 2.5€ per m³. This research contributes to the development of more effective and environmentally friendly wastewater treatment strategies for emerging contaminants. Full article

Red Amaranth (RA) Azo dye is a persistent pollutant in wastewater and stands as a toxicological risk, which has led to the development of effective methods for its removal and photocatalytic degradation. Therefore, CeO₂ nanoparticles were synthesized by a controlled precipitation method, and Ultraviolet-Visible (UV–Vis) analysis and Tauc plots yielded a band gap of ~3.24 eV. The CeO₂ nanoparticles showed the fluorite cubic phase, and nearly spherical particles with an average size of ~10 nm. Nitrogen physisorption revealed a type IV isotherm with a Brunauer–Emmett–Teller (BET) surface area of 85.27 m²·g⁻¹ and a total pore volume of 0.27 cm³·g⁻¹, indicating a mesoporous structure and high surface accessibility. The chemical behavior showed Ce and O, consistent with phase purity. Photocatalytic performance was evaluated in 20 ppm aqueous solution of RA under 365 nm UV irradiation (LED 100 W), with a temperature of ~20 °C and a 15 min dark adsorption step. Concentration decay was followed at λ_max = 520 nm by Lambert–Beer. The degradation efficiency η and pseudo-first-order kinetic were obtained from ln(C₀/C_t) vs. time. In addition, chemical oxygen demand (COD) tests were performed on RA solution before and after photodegradation, showing a COD reduction of ~85% (from 19.8 to 3 mg O₂·L⁻¹), which corroborates mineralization beyond chromophore bleaching. Under [C₀ = 20 mg·L⁻¹] and [m_cat = 1.0 g·L⁻¹], CeO₂ achieved [RA = 90% at 180 min, k = 0.0125 min⁻¹]. These results demonstrate that CeO₂ is an effective photocatalyst for RA degradation under UV-A irradiation, integrating adsorption, kinetic behavior, and mineralization performance into a coherent structure–property relationship. Full article

Advanced glycation end products (AGEs) are important biomarkers associated with diabetes and metabolic disorders; yet existing detection methods are invasive and unsuitable for frequent monitoring. This study aimed to develop a non-invasive and portable AGEs detection device, optimize strategies for mitigating pigmentation-related interference, and evaluate its feasibility for metabolic assessment. The proposed system employs a 365 nm ultraviolet LED excitation source, an optical filter assembly integrated into an ergonomic dark chamber, and an eyelid-signal-based algorithm to suppress ambient light and skin pigmentation interference. Simulation experiments were conducted to evaluate the influence of different pigment colors and skin tones on fluorescence measurements. A clinical study was performed in 200 participants, among whom 42 underwent concurrent serum AGEs measurement as the reference standard. Predictive models combining corneal fluorescence signals and body mass index (BMI) were constructed and evaluated. The results indicated that purple and blue pigments introduced greater interference, whereas green and pink pigments had minimal effects. Device-derived AGEs estimates demonstrated good agreement with serum AGEs, with a mean error below 8%. A hybrid model incorporating BMI achieved improved predictive accuracy compared with single-parameter models. Participants with high-AGE dietary habits exhibited elevated fluorescence signals and BMI. These findings suggest that the proposed device enables stable and accurate non-invasive AGEs assessment, with potential utility for metabolic monitoring. Incorporating lifestyle-related parameters may further enhance predictive performance and expand clinical applicability. Full article

New strawberry cultivars with unusual peel colors, such as white and peach, require thorough characterization to understand their quality traits. In this study, we examined three Japanese cultivars, ‘Kotoka’ (red), ‘Awayuki’ (peach), and ‘Pearl White’ (white), to investigate their differences in chemistry and optical properties. We measured the sugar content, acidity, and maturity index, and combined these with fluorescence spectroscopy and imaging under three LED lights (365 nm, 420 nm, and white). The fluorescence data showed clear differences between cultivars, in which the ‘Pearl White’ gave a strong near-UV peak around 290/325 nm, ‘Awayuki’ had a high far-red signal in 490/745 nm, and ‘Kotoka’ showed lower fluorescence overall. Imaging backed up these findings, with ‘Pearl White’ and ‘Awayuki’ looking brighter under UV while Kotoka appeared darker and more uniform. Texture analysis showed ‘Pearl White’ had a more uneven surface, while ‘Kotoka’ was smoother. The basic chemistry also matched these trends, as ‘Kotoka’ had the most sugar and acid, giving it a sharper taste, while ‘Pearl White’ had the highest maturity index and a milder flavor. These results demonstrate how fluorescence fingerprints and imaging features, when combined, can rapidly characterize strawberry types and assess their quality without damaging the fruit. Full article

This study investigates the influence of photoinitiating systems on the degree of methacrylate group conversion and the rate of polymerization in UV/LED-curable nail gel formulations. Camphorquinone and Eosin Y, commonly used in medical and dental applications, were evaluated in bimolecular systems with onium and iodonium salts, thiols, and amines as co-initiators. Real-time FT-IR spectroscopy was employed to monitor polymerization under dual-LED irradiation (365 nm and 405 nm). The results demonstrate that the tested systems, inspired by photocurable medical products, exhibit significant potential for application in highly pigmented nail gels, achieving efficient curing with low residual monomer content. Full article

Neutrophils are the first line of defense of the human immune system against pathogens. Photobiomodulation, mediated by mitochondrial photoacceptors such as cytochrome c oxidase, has emerged as a method to modulate neutrophil function through targeted light exposure. Despite the extensive characterization of neutrophil extracellular traps (NETs) formation (NETosis), the wavelength-specific modulation of neutrophil photoactivation and the involvement of redox pathways remain poorly defined. In this study, the effects of monochromatic (365 nm, 415 nm, 437 nm, and 625 nm) and dichromatic LED-light irradiation on NETs formation were systematically examined. The highest netotic responses were elicited by UV-A (365 nm) and violet-blue light (415 nm), whereas 437 nm showed the lowest induction and 625 nm stimulated a moderate netotic response. The pharmacological inhibition of NETosis induced by 365 nm and 415 nm irradiation with specific NADPH oxidase inhibitor, apocynin, and mitochondrial reactive oxygen species (mtROS) scavenger, MitoTEMPO, attenuated NETs formation by engaging both enzymatic and mitochondrial oxidative sources. Notably, mtROS played a dominant role under 415 nm stimulation in contrast to 365 nm-induced NETosis as demonstrated by higher sensitivity to MitoTEMPO. Importantly, combined simultaneous irradiation with 415 nm and 625 nm LEDs resulted in a significant suppression of NETs formation by more than 50%, highlighting a potent inhibitory synergy observed for the first time and suggesting a new approach of wavelength pairing to modulate neutrophil activation. These results were further supported by measurements of ROS production using a luminol-amplified chemiluminescence assay. Collectively, these findings delineate a wavelength- and ROS-dependent framework for light-induced neutrophil activation, with mitochondrial pathways exerting central control particularly under short-wavelength irradiation. Full article

This work analyzes the performance of a photoreactor built with UV-LED technology. For this task, a UV-LED wavelength of 365 nm was used as an irradiation source, and it was electrically and spectrally characterized to ensure correct operation. To evaluate the functionality, the photoreactor was tested on the degradation of Rhodamine B (Rh B), a dye commonly used in the textile industry. The experiment was conducted under optimal conditions, using a concentration of 17 ppm of Rh B and 100 mg of zinc oxide (ZnO) as a photocatalyst in a glass reactor. The mixture was continuously stirred for 120 min, achieving 99.42% efficiency. The results showed that the UV-LED photoreactor performs well in activating ZnO for the removal of Rh B from the solution, highlighting its potential for treating textile industry wastewater. The use of LEDs offers advantages such as energy efficiency and lower environmental impact compared to traditional UV lamps. ZnO, known for its reactivity under UV light, acted as a stable photocatalyst, ensuring complete degradation of the dye without producing harmful by-products. This method provides an efficient approach to dye removal in wastewater treatment, promoting cleaner and more sustainable industrial practices. Full article

The use of ultraviolet (UV) for water disinfection is known for its chemical-free process and with no harmful disinfection by-products. Yet, the disinfection process remains time-consuming, and many studies are limited to disinfection of one or two microbial species. Direct photolytic and glass-embedded TiO₂ photocatalytic disinfection of four different bacterial species (Staphylococcus aureus, Salmonella senftenberg, Bacillus subtilis, and Escherichia coli) were assessed using UV-LED radiation with wavelengths of 365 nm. The optimization of the UV disinfection under different masses of the TiO₂ photocatalyst was evaluated. Additionally, the order of disinfection of the different bacteria species was assessed. The disinfection effects were measured based on the potential to reduce the number of bacteria species, calculated in colony-forming units/mL and log reduction units. The disinfection of Staphylococcus aureus was enhanced from 1.46 log reduction units in the UV-alone treatment to a high of 5.65 log reduction units in the UV + 0.08 g TiO₂ treatment. Regarding Salmonella senftenberg, disinfection was enhanced from 1.26 log reduction units to 3.85 log reduction units in UV-alone experimental treatments and UV + 0.04 g TiO₂, respectively. Similarly, an increase in Bacillus subtilis reduction was achieved from a low of 0.69 log reduction units to a high of 2.98 log reduction units in UV-alone treatments and UV + 0.08 g TiO₂, respectively. The disinfection of Escherichia coli was enhanced from 2.49 log reduction units (UV-alone treatment) to a high of 6.35 log reduction units (UV + 0.02 g TiO₂). The findings provide key implications and new insights into the studied bacteria species and the future application of porous glass-embedded TiO₂ photocatalysts to enhance bacteria disinfection using UV light for improved water. Full article

A novel method for the development of fingerprints in environmentally friendlier conditions and on porous surfaces with 1,8-diazafluoren-9-one (DFO) is reported herein. DFO, a fluorescent dye was formulated in glacial acetic acid, methanol, and a minimum amount of methylene chloride. The DFO reacted with amino acid components of latent prints, resulting in a fluorescent species that was visualized under daylight, UV light at 254 nm, 365 nm, and LED at 395–405 nm. The developed prints were photographed using iPhone 11 and IOS 17.4.1. The fluorescent spectra of the species resulting from DFO’s reaction with the amino acid glycine and the wavelengths of maximum excitation (λ_ex = 470 nm) and emission (λ_em = 585 nm) were also reported. The method is suitable for forensic laboratories. Full article

Humulones are a family of homolog natural products obtained from the strobiles of humulus lupulus, or hops plants. Structurally, they consist of substituted phloroglucinols with two isoprenyl side chains, a carbonyl group and a quaternary ring carbon substituted with a hydroxyl group. The three most prominent homologs are n-, co- and ad-humulone, containing isobutyl, isopropyl and secbutyl ketone groups, respectively. When solutions of humulones are exposed to UV light, they undergo stereoselective isomerization to the five-membered ring trans-isohumulones. A photoreactor was assembled from strip LEDs in close contact with UV-transparent tubing. This reactor allowed continuous-flow chemical synthesis of the isohumulones. The yield, conversion and product throughput are compared for the humulones, using LEDs emitting white, blue and ultraviolet light (visible, 400 nm, and 365 nm, respectively). Using an optimized continuous-flow reactor, a throughput of 0.43 g/h was obtained for trans-n-isohumulone. Full article

This study investigated the effects of several light spectra on Stevia rebaudiana, analysing growth parameters, yield, and physiological responses within a controlled-environment agriculture (CEA) system. The experimental design involved different light treatments, including specific combinations of blue (435 nm and 450 nm), red (663 nm), and ultraviolet (UV) wavelengths (365 nm), to determine their impact on morphological development and biochemical properties, particularly focusing on the production of the sweetening compounds stevioside and rebaudioside A. Stevia rebaudiana plants cultivated from cuttings sourced from a reputable UK nursery (Gardener’s Dream Ltd., Glasgow, UK) were subjected to these spectral treatments over a period of five weeks under vertical farming conditions. Physiological measurements, such as chlorophyll fluorescence (Fv/Fm), stomatal conductance, and leaf temperature, were recorded, alongside growth metrics (plant height, leaf area, and biomass). This study also incorporated high-performance liquid chromatography (HPLC) to quantitatively analyse the influence of the light treatments on the sweetener concentration. The results demonstrated that targeted LED spectra, particularly those that include UV light and blue light (435 nm), significantly nhanced both the quantitative and qualitative attributes of stevia growth, indicating that strategic light management can markedly improve the nutritional and commercial yields of Stevia rebaudiana. This research contributes to the optimisation of light conditions in vertical farming systems, aiming to enhance agricultural efficiency and reduce the reliance on imported stevia by maximising local production capabilities. Full article

In this study we report on the efficiency of a furane-indole-chromenone-based organic derivative (FIC) as a photocatalyst in the α-arylation of enol acetate upon LED irradiation at 405 nm, and as a photoinitiator/photocatalyst in the free radical polymerization of an acrylate group in the presence of bis-(4-tert-butylphenyl)iodonium hexafluorophosphate (Iod) as an additive, or in the presence of both Iod and ethyl-4-(dimethyl amino) benzoate (EDB) under LED irradiation at 365 nm. The photochemical properties of this new light-sensitive compound are described, and the wide redox window (3.27 eV) and the high excited-state potentials FIC*/FIC^●− (+2.64 V vs. SCE) and FIC^●+/FIC* (−2.41 V vs. SCE) offered by this photocatalyst are revealed. The chemical mechanisms that govern the radical chemistry are discussed by means of different techniques, including fluorescence-quenching experiments, UV-visible absorption and fluorescence spectroscopy, and cyclic voltammetry analysis. Full article