Search Results (625)

The tympanic membrane (TM) is a thin, semi-transparent structure whose morphology and optical appearance provide important diagnostic cues. In the early stages of middle-ear pathology, subtle shape and compliance alterations may precede overt clinical signs, making them valuable early indicators of disease. Such structural changes are difficult to assess reliably using conventional (micro-)otoscopy, which lacks quantitative depth information and is operator-dependent. Data-driven monocular image analysis could enable quantitative assessment of TM geometry and compliance, but the limited availability of annotated three-dimensional datasets constrains the development of these methods. At the same time, realistic simulations of TM appearance remain challenging due to its complex reflectance and transmission behavior. The present study focuses on physiologically healthy tympanic membranes, which provide the baseline anatomical and optical model required before subtle pathological changes can be investigated. This work introduces a parametric physically grounded rendering model of the structures visible during otoscopy: the tympanic membrane, ear canal, and malleus–incus complex. Implemented in the open-source software Blender™ using procedural geometry nodes and physically motivated shaders, the framework generates anatomically plausible three-dimensional geometries via statistical parameter sampling and controlled mesh deformation. Optical appearance is simulated using a computationally efficient layered shading model based on literature-derived tissue reflectance, transmission, and scattering properties. A camera–projector setup models both conventional white-light otoscopy and structured-light imaging, enabling the generation of paired intensity images and corresponding depth maps. The proposed framework establishes a physically grounded representation of the human ear and enables a controllable, extensible modeling pipeline for virtual training, biomechanical finite element analysis, and synthetic data generation for supervised learning. Full article

Graphene quantum dots (GQDs) with distinct optical responses were prepared from pyrene using urea, melamine, and 2,4-pyridinedicarboxylic acid as nitrogen-containing regulators and were subsequently combined with ZIF-8 for visible-light-driven CO₂ reduction. FT-IR, Raman, XRD, optical spectroscopy, representative high-magnification transmission electron microscopy, and X-ray photoelectron spectroscopy (XPS) showed regulator-dependent structural, compositional, and optical differences. XPS detected surface nitrogen in all three GQD samples, with the highest N content in y-GQDs, while the relative N 1s component distributions differed across the series. At a nominal 4 wt% GQD addition, r-GQDs/ZIF-8 gave the highest observed mean CO and CH₄ formation rates of 23.51 ± 0.48 and 4.08 ± 0.15 μmol·g⁻¹·h⁻¹, respectively, corresponding to approximately 2.9- and 4.5-fold increases over pristine ZIF-8. This sample also showed the lowest fitted charge-transfer resistance, the highest mean photocurrent density, and the fastest qualitative time-resolved photoluminescence decay among the compared composites. Across three independent five-cycle tests, 83.78 ± 0.54% of the initial combined CO and CH₄ rate was retained. These results establish correlations among regulator identity, surface composition, optical relaxation, photoelectrochemical response, and catalytic activity, but do not determine a unique charge-transfer pathway or exclude contributions from surface basicity, CO₂ adsorption, and nominal-loading differences. Full article

Betanin is the main betacyanin and major pigment extracted from red beets (Beta vulgaris). While its applications as food colorant, color-based sensors, antioxidant, anti-inflammatory, and antimicrobial traits are well-known, this natural dye is underestimated and underexploited in the field of light- and electric-responsive materials and devices. This comprehensive review describes the optical properties and molecular orbitals of this chromophore, along with its excited-state relaxation dynamics and emission quantum yields. Other relevant and basic behaviors of its excited-state features, such as cis-trans-photoisomerization, singlet–singlet energy transfer, photo-induced electron transfer, photosensitization of ¹O₂, and relative photo-instability are also presented in some relevant details. Photoconductive materials based on betanin and their related devices such as organic light emitting diodes, and dye-sensitized solar cells, are also surveyed. Other visible light-driven processes such as photodynamic processes and heterogeneous catalysis based on betanin-containing assembly/composites are demonstrated. Finally, the use of betanin as nonlinear optical materials is addressed. Full article

Building facades and construction materials are continuously exposed to airborne particulate matter, organic pollutants, and microbial colonization, which cause progressive soiling, aesthetic degradation, and structural deterioration while imposing high maintenance and energy burdens. Photocatalytic titanium dioxide (TiO₂) has emerged as the most widely studied material for imparting self-cleaning functionality to building surfaces, owing to its ability to mineralize adsorbed contaminants under solar irradiation and to modulate surface wettability. This narrative review provides a structured account of TiO₂-based self-cleaning coatings for building materials, organized around three complementary themes: surface mechanisms, performance metrics, and outdoor durability. We first rationalize the two intertwined self-cleaning mechanisms—photocatalytic oxidative degradation and photoinduced superhydrophilicity—and their combination with physically repellent (superhydrophobic/superamphiphobic) wetting states. We then survey the principal coating-design strategies, including morphology and facet engineering, SiO₂-TiO₂ composites, metal/non-metal doping and heterojunction construction for visible-light activation, and dual-functional photocatalytic–superhydrophobic systems, and their integration into cementitious substrates, natural stone and cultural heritage, and transparent glass/photovoltaic surfaces. The quantitative metrics used to benchmark self-cleaning performance—water contact angle, dye photodegradation, NO_x and VOC abatement, and antimicrobial activity—are critically discussed together with the limitations of standardized laboratory tests. Finally, we analyze the weathering-induced deactivation pathways (photocatalyst leaching, surface contamination by soluble salts, and UV aging of organic matrices) and the emerging strategies for durable coatings, including inorganic binders, light-driven hydration, and defect- and heterojunction-engineered photocatalysts. The review concludes with an outlook on the open challenges that must be addressed to translate these coatings from laboratory demonstrations to long-lived, large-scale building applications. Full article

Underwater images captured by sensors suffer from low contrast and blurry details due to the interference of light absorption and scattering in underwater scenes. Good visibility restoration is often desired for practical processing applications. Current image enhancement methods often rely on prior assumptions to reconstruct a clear image without considering the inherent correlation of underwater image degradation, introducing unconsiderable enhancement results. Thus, this paper proposes an underwater enhancement method based on multiple enhanced layers fusion and transmission-driven color restoration, named EFCR, which consists of three key modules: a pixel-based transmission computation (PTC), a multiple-enhanced-layers fusion (MELF), and a transmission-driven color restoration (TCR). First, PTC designs a linear transformation to adjust the saturation and estimates the transmission based on the mapping relationship between the transmission, the brightness, and the saturation, preventing the transmission from being under-estimated. Then, MELF extracts the original details from the luminance channel and enhances these desired details based on the estimated transmission. Meanwhile, adaptive histogram equalization is used to improve the global brightness. Finally, TCR further analyzes the inherent correlation between the transmission and the image degradation, and constructs a compensation factor to adaptively correct the attenuated a and b channels of Lab space, producing a good enhancement result with reasonable brightness and natural colors. Extensive experiments on three underwater image datasets demonstrate the effectiveness and robustness of the proposed method in underwater image restoration. Especially, the average $\overline{r}$ and Blur values of our method at most incline and decline by 99.87% and 10.22%, respectively, which shows our method has obvious advantages in edge enhancement and haze removal. Moreover, our method provides helpful support for color restoration and image salient detection, and also shows good generalization capability for enhancing outdoor hazy images. Full article

Conjugated polymers featuring donor–acceptor (D-A) architectures have emerged as promising candidates for visible-light-driven hydrogen evolution, owing to their tunable optoelectronic properties. However, achieving high photocatalytic activity without noble-metal cocatalysts remains challenging. Herein, we report a series of D-A type conjugated polymers based on dibenzothiophene sulfone (BTDO) as an electron acceptor and 3,4-ethylenedioxythiophene (EDOT) as an electron donor, synthesized via Suzuki polycondensation. By optimizing the donor/acceptor feed ratio, the optimal copolymer, EDOT-BTDO-5, delivers a hydrogen evolution rate (HER) as high as 87.5 mmol h⁻¹ g⁻¹ was achieved under visible-light irradiation (λ > 420 nm) without any Pt cocatalyst. To further boost the charge separation efficiency, a thiophene π-bridge was introduced, yielding a D-A-π-A ternary copolymer, EDOT-BTDO-T, which exhibits a significantly enhanced HER of 103.45 mmol h⁻¹ g⁻¹, along with remarkable operational stability, retaining ~69% of its initial activity after 20 h of continuous illumination. Comprehensive characterization, including photoelectrochemical analysis and density functional theory (DFT) calculations, reveals that the incorporation of EDOT broadens the visible-light absorption range, while the thiophene π-bridge extends π-conjugation, and facilitates efficiency. This work demonstrates a molecular engineering strategy to construct high-performance, metal-free organic photocatalysts by tailoring D-A and D-A-π-A architectures, providing valuable insights for sustainable photochemical energy conversion. Full article

Background/Objectives: Patients with fixed orthodontic appliances are at increased risk of plaque accumulation, gingivitis, and caries because brackets and bands hinder mechanical hygiene. This study evaluated whether regular home use of dual-light antibacterial photodynamic therapy (aPDT) supports oral hygiene during fixed orthodontic treatment in adolescents. Methods: In a single-center, randomized, assessor-blinded trial, forty-one adolescents starting fixed orthodontic treatment were randomised to a Control group (standard hygiene) or a Test group (standard hygiene plus home-use dual-light aPDT). Visible Plaque Index (VPI%), Bleeding on Probing (BOP%), and Orthodontic Plaque Index (OPI) were assessed at baseline and 12 weeks by an assessor blinded to allocation. After two protocol-driven exclusions, 39 participants (20 Test group, 19 Control group) were analysed. Site-level proportions were compared using the chi-square test. Results: VPI decreased in both groups, with a larger mean within-group reduction in the Test group (−7.0%) than in the Control group (−3.7%); exploratory site-level analysis showed a greater reduction in plaque-positive sites in the Test group at 12 weeks (p < 0.001). BOP increased in both groups but to a smaller extent in the Test group (mean +2.4% versus +5.7%), and a higher proportion of Test-group participants maintained BOP ≤ 10% (85% versus 58%); bleeding-positive sites were lower in the Test group at 12 weeks (p < 0.001). The Test group also showed a flatter distribution of OPI scores around orthodontic brackets. No device- or protocol-related adverse events were reported. Conclusions: In adolescents undergoing fixed orthodontic treatment, regular home use of dual-light aPDT was safe and associated with better site-level plaque and bleeding control, with directional but non-significant trends at the participant level. The findings support further evaluation of dual-light aPDT as an adjunct to mechanical hygiene during this vulnerable treatment period. Full article

The continuous release of pharmaceutical contaminants such as naproxen (NPX) into aquatic environments poses substantial ecological risks. In this study, a series of visible-light-responsive bismuth oxychloride-iodide (BiOCl_xI_1−x) solid solutions were synthesized via a simple one-step solvothermal method. XRD analysis confirmed the formation of a tetragonal matlockite-type solid solution, while SEM and TEM observations revealed three-dimensional flower-like hierarchical microspheres assembled from ultrathin nanosheets. Among the prepared samples, BiOCl_0.3I_0.7 exhibited the highest visible-light photocatalytic activity toward NPX degradation, achieving a removal efficiency of 87% within 60 min. Its apparent pseudo-first-order rate constant was 0.0740 min⁻¹, the highest among the investigated compositions. Experimental measurements showed composition-dependent band-gap narrowing, while representative DFT calculations indicated that I-for-Cl substitution modifies the valence-band electronic states, providing a qualitative electronic-structure explanation for the enhanced visible-light response. Evaluation of operational parameters showed that NPX degradation was favored at lower initial NPX concentrations and under acidic conditions, whereas humic acid and bicarbonate (HCO₃⁻) inhibited the process. TOC analysis further confirmed partial mineralization of NPX during photocatalysis. Electron paramagnetic resonance (EPR) analysis and reactive-species trapping experiments indicated that photogenerated holes (h⁺), singlet oxygen (¹O₂), and superoxide radicals (O₂^•−) were the dominant reactive species involved in NPX degradation. These findings demonstrate the potential of band-gap-engineered bismuth-based solid solutions for environmental remediation. Full article

Visible-light-driven decarboxylative alkylation faces challenges from the inertness of Pd-catalyzed oxidative addition of unactivated alkyl halides and the complexity of dual photoredox/metal systems. In this study, we present the first utilization of unsymmetrical N,C,Se-pincer NHC-Pd(II) complexes as single-component photocatalysts for the coupling of arylacrylic acids with unactivated alkyl bromides under blue light. The reaction is conducted at room temperature with catalyst loading of 0.5 mol%, delivering a wide range of alkenylalkane products in yields ranging from 31% to 88%, exhibiting excellent tolerance to halogens and unprotected phenols. Control studies have revealed that the selenoether donor stabilizes active Pd species and enables a radical-mediated pathway. This work extends the utility of N,C,Se-pincer Pd catalysts to reductive C−C coupling and provides a practical platform for biomass valorization. Full article

This study fabricated a silver-based composite photocatalytic material (Ag/AgVO₃/g-C₃N₄) for antibiotic degradation driven by visible light. The composite was prepared using the water bath method, and its morphology, structure and optical properties were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and Ultraviolet-Visible (UV-vis) diffuse reflection spectroscopy. The photocatalytic activity of the composite was evaluated within 240 min under visible-light irradiation, and its degradation effect was quantified using tetracycline hydrochloride as the target pollutant, applying different conditions of composite proportions and dosage, initial concentration of the contaminant, and pH. The experimental results demonstrated that the composite doped with Ag⁺ had a higher degradation effect on tetracycline hydrochloride. The highest degradation rate of tetracycline hydrochloride (reaching 86.64%) was achieved at a composite ratio of Ag/AgVO₃/5g-C₃N₄, dosage of 0.8 g·L⁻¹, and initial concentration of tetracycline hydrochloride of 10mg·L⁻¹. This rate is approximately 1.4 times and 1.7 times those of the pure-phase g-C₃N₄ and AgVO₃, and the degradation rate remains stable at 81.52% after 4 cycles of experiments. The favorable stability of the photocatalyst was also verified through a stability test. Full article

The transformation of toluene to benzaldehyde via green and sustainable routes is of great significance in the fine chemical industry. However, hard activation of benzylic C(sp³)-H bonds and facile overoxidation of the generated benzaldehyde collectively render the selective oxidation of toluene extremely challenging. In this study, we constructed a core–shell heterostructure photocatalyst, CeO₂@NiFe-LDH, employing molecular oxygen as the oxidant. Under mild conditions of room temperature and visible-light illumination, the catalyst achieves a toluene conversion rate of 1.936 mmol·g⁻¹·h⁻¹ with an excellent benzaldehyde selectivity of 81.0%, and its catalytic performance is significantly superior to that of the individual single-phase materials and the simple physical mixture. Optical and electrochemical measurements confirm enhanced visible-light absorption and utilization, as well as greatly improved separation and migration efficiency of photogenerated charge carriers. Furthermore, the CeO₂@NiFe-LDH heterostructure features staggered band alignment, promoting S-scheme charge transfer across the heterointerface, thereby substantially boosting the redox capacity of the composite catalyst. Consequently, the photogenerated carriers with high reactivity are fully engaged in catalytic reactions, enabling efficient carrier utilization and ultimately leading to a significantly enhanced photocatalytic performance. This study not only demonstrates the outstanding application potential of CeO₂@NiFe-LDH for the visible-light-driven selective oxidation of toluene to benzaldehyde, but also offers a novel strategy for enhancing the photocatalytic performance of LDH-based materials. Full article

This study reports the synthesis and comprehensive characterization of a novel 5% cadmium-doped cerium oxide/reduced graphene oxide (5% Cd-CeO₂/rGO) nanocomposite for the enhanced visible-light-driven photocatalytic degradation of methyl orange (MO). The nanocomposite was prepared using a simple co-precipitation method followed by thermal reduction, which integrates the excellent electron-transport properties of reduced graphene oxide (rGO) with the oxygen-vacancy-rich characteristics of Cd-doped CeO₂, resulting in improved photocatalytic performance. The successful synthesis of the nanocomposite and the direct interaction between the rGO sheets and ultrafine CeO₂ nanoparticles were verified through structural and morphological analyses using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Transmission Electron Microscopy (TEM), and Scanning Electron Microscopy (SEM). XPS results indicated an increase in the Ce³⁺ concentration and oxygen vacancy density after Cd doping and rGO incorporation, both of which play a crucial role in enhancing photocatalytic activity. Under visible-light irradiation, the 5% Cd-CeO₂/rGO nanocomposite exhibited substantially higher photocatalytic activity and methyl orange (MO) degradation efficiency than pristine CeO₂ and reduced graphene oxide (rGO). The improved photocatalytic performance demonstrates the beneficial role of combining metal-ion doping with conductive carbon supports to facilitate charge separation and electron transport in semiconductor photocatalysts. The developed nanocomposite also shows promising potential for the design of next-generation semiconductor-based materials for photocatalytic, energy conversion, and optoelectronic applications. Full article

Solar-driven photocatalytic water splitting is a promising approach for green hydrogen production. Despite the great potential of g-C₃N₄ photocatalysts, non-metal doping studies currently suffer from conflicting results and unclear doping configurations. Herein, first-principles calculations were adopted to compare P-, O-, and S-doped g-C₃N₄. P-g-C₃N₄ with P substituting N shows the best stability, a narrower band gap, and enhanced visible light absorption. It achieves high carrier mobility and suitable band edges for overall water splitting, with a maximum STH efficiency of 15.8%. This work clarifies doping mechanisms and offers solid theoretical support for developing high-performance g-C₃N₄-based photocatalysts. Full article

The synthetic industry has shortened human lifespans because of environmental contamination. Numerous physicochemical methods can be used to decompose the released organic contaminants, but heterogeneous photocatalysis stands out among them. The creation of a novel sunlight-active heterogeneous photocatalyst, ZVI@MnFe₂O₄/PTh, for possible degradation of RhB dye is discussed in this study. The nanocomposite was fabricated using the hydrothermal method and in situ polymerization of thiophene. The ternary composite photocatalyst (ZVI@MnFe₂O₄/PTh) and photocatalysts (ZVI@MnFe₂O₄ and MnFe₂O₄/PTh) were well characterized in terms of structure (Fourier transform infrared spectroscopy), morphology (scanning electron microscopy), composition (energy-dispersive X-ray), and crystallinity (X-ray diffraction). UV–visible spectroscopic analysis (Tauc plot) was used to determine the energy bandgaps of catalysts. The characterization study supports the successful assembly of ZVI@MnFe₂O₄ nanoparticles and polythiophene. To evaluate the photocatalytic performance, the photocatalytically helped degradation of Rhodamine B dye from wastewater was also investigated over the new catalysts. The designed heterojunction enhances photogenerated charge separation and stimulates the photocatalytic process. The proposed study’s findings demonstrated that the novel composite’s sunlight-active photocatalytic effectiveness (99% in 90 min at pH 4) was enhanced against the degradation of Rhodamine B dye. Different models were utilized to predict the reaction’s kinetics, and RSM was utilized as a statistical technique to examine the individual and then interaction effects of the influencing parameters. The RSM results were supported by the numerical values of the optimized parameters, which were pH = 4, H₂O₂ = 10 mM, and composite dose = 20 mg/50 mL, utilizing a 100 ppm RhB solution. Full article

Visible light communication (VLC) has emerged as a transformative optical wireless technology for sixth-generation (6G) networks, offering license-free spectrum access, inherent electromagnetic-interference immunity, high spatial confinement, and the unique ability to combine high-speed wireless connectivity with solid-state lighting infrastructure. However, the transition from conventional VLC links to practical 6G optical wireless systems requires far more than advanced modulation and signal processing. Future VLC performance will be strongly determined by the co-design of photonic front-ends, including high-speed transmitters, spectrally engineered emitters, reconfigurable optical interfaces, intelligent receivers, and energy-autonomous detection units. This article provides a comprehensive, device-centered review of photonic hardware and artificial intelligence (AI) enablers for next-generation 6G VLC systems. Particular attention is given to micro-LEDs, laser diodes, color-conversion materials, including perovskite quantum dots, advanced photodetectors, imaging receivers, wavelength-shifting fiber receivers, solar-cell-based receivers, optical reconfigurable intelligent surfaces (RISs), metasurfaces, beam-steering components, and optical wireless power transfer. This review discusses how AI can support inverse photonic design, transmitter and receiver calibration, nonlinear impairment mitigation, channel-aware beam control, and energy-aware resource management. Unlike broader VLC surveys that mainly emphasize network architecture, this article provides a device-centered perspective on AI-enabled photonic integration for 6G VLC, supported by a comprehensive survey of recent experimental demonstrations. Key challenges related to bandwidth, optical efficiency, receiver field of view, mobility, safety, standardization, and practical deployment are summarized, followed by a research roadmap for 2025–2032. Full article