Search Results (8,077)

Silver nanoparticles synthesized using natural polysaccharides have received attention for their biocompatibility and potential selective anticancer activity. In this study, the physicochemical properties and biological activity of silver nanoparticles prepared using gums from Acacia senegal (ASS) and Acacia seyal (ASY) were compared. The gums were analyzed to determine their physicochemical characteristics and used as natural reducing and stabilizing agents in nanoparticle synthesis. The resulting nanoparticles were characterized using UV–visible spectroscopy, FTIR, dynamic light scattering, and zeta potential analysis. Their cytotoxicity was evaluated in MCF-7 breast cancer cells and HEK-293 normal cells using MTT assay, flow cytometry, and intracellular reactive oxygen species (ROS) measurement. Both gums showed properties consistent with Gum Arabic, with a higher protein content in ASS. ASS-derived nanoparticles were smaller and had greater colloidal stability. Both formulations reduced MCF-7 cell viability in a dose-dependent manner, with lower IC₅₀ values observed for the ASS-based nanoparticles. Apoptosis induction was associated with increased ROS generation. Limited cytotoxicity toward HEK-293 cells resulted in favorable selectivity indices. Acacia gum–mediated silver nanoparticles demonstrate selective anticancer activity, and gum composition significantly influences nanoparticle stability and bioactivity, supporting their potential application in breast cancer nanotherapy. Full article

Virtual plant models combined with ray-tracing simulations are an established tool for evaluating plant–light interactions. Current approaches often simplify leaf surface properties by assuming diffuse reflectance behavior, despite experimental evidence that leaf reflectance is direction-dependent across much of the visible spectrum. This study investigates whether incorporating measured, spectrally resolved and direction-dependent (BRDF) reflectance properties into these models affects simulation outcomes. Using virtual 3D cucumber (Cucumis sativus) plant models with PhongShader-based optical leaf characteristics for BRDF consideration, light absorption and local photon flux densities were simulated under a wide range of lighting conditions, including diffuse and directed sunlight scenarios. While total light absorption at the leaf level is only marginally affected (mean absolute percentage error, MAPE < 2%), spectral distortions in leaf surroundings, especially under direct light, exceeded 8% in the blue wavelength range. Beyond their relevance for estimating photosynthetic rates, such distortions directly affect the spectral composition within the canopy, which is particularly critical in greenhouse applications where optical sensors are used to monitor spectral ratios and, therefore, require the accurate prior simulation of canopy light conditions. This is particularly relevant for setups with directional artificial lighting. The findings suggest that BRDF modeling is not critical for calculating photosynthetic rates under most conditions, but is required in spectral analyses or for optimizing artificial lighting designs. Full article

Peroxydisulfate (PDS, S₂O₈²⁻) is an important oxidant for a wide range of industrial applications, including organic synthesis, polymer preparation, wastewater treatment and environmental remediation. Currently, PDS is commercially produced by electrolysis of sulfate solution. Photoelectrochemistry (PEC) provides an alternative approach to PDS generation by reducing the energy required to drive this process. Because PEC uses solar light as an abundant, free resource, it is an attractive technique for PDS generation compared to electrolysis. WO₃, owing to its excellent stability in acidic environments, is an excellent metal oxide candidate for producing PDS. Withstanding stronger acidic pH as well as absorption of visible light as a major fraction of solar light renders WO₃ a promising material for PEC-based PDS production when compared with other semiconductors. This mini review examines light-assisted, sustainable production of PDS on WO₃ photoanodes. It mainly involves the oxidation of the anion bisulfate, HSO⁴⁻, in a highly acidic pH. The efficiency of photoelectrochemical generation of PDS is greatly influenced by important factors, including suppressing recombination of photoinduced charge carriers, cocatalyst loading, minimizing competing side reactions, and establishing coupled reactions. In this review, we briefly discussed the key highlights to date in the application of WO₃ as a stable photoanode material for producing PDS. It provides insight into the potential of photocatalysis as an emerging route for the sustainable synthesis of PDS as a valuable chemical oxidant. Besides the significant progress made so far, the PDS production rate remains low, and minimizing the recombination tendency to achieve a higher photocurrent density could further boost PEC-based PDS production. Full article

This study uses a process-based technical approach combining X-ray radiography, visible and raking-light examination, and cross-modal image comparison to assess the construction logic of a Cubist-period painting associated with Pablo Picasso. Across the X-ray dataset, the painting shows orientation-dependent structural coherence, hierarchically organized planning seams with mechanically sensible terminations, and a multistage base-layer construction that remains interpretable under grayscale inversion and rotation. Visible and raking-light images reveal physically incised inscriptions, names, places, and numerals with later paint settling into grooves and, in some areas, bridging over them, establishing a clear sequence in which inscriptions precede overpainting. Reduced color and polarity-inversion checks confirm that these features are carried by luminance and surface relief rather than color artifacts. Together, these converging lines of evidence support an interpretation of a multi-campaign, orientation-aware construction process consistent with documented working methods from Picasso’s relevant period and difficult to replicate by superficial imitation. Full article

We report the enhancement of organic photodetector (OPD) performance through the incorporation of CsPbBr₃ perovskite nanocrystals (PNCs) into P3HT:PCBM devices. The optimized device (HPD_01) exhibits a maximum responsivity of 0.083 A/W and a specific detectivity of ~4.7·10¹⁰ Jones, and a minimum NEP of 5.2·10⁻¹² W·Hz^−1/2 at the self-powered operating point (V ≈ 0 V), outperforming the nanoparticle-free reference. Frequency- and distance-dependent measurements under visible light communication conditions demonstrate that the optimized device maintains strong signal detection up to 1 MHz and at distances exceeding 15 cm. Notably, the external quantum efficiency spectra reveal an additional contribution in the 450–575 nm range, which is absent in the reference device. This enhancement is consistent with a radiative absorption–reemission energy-transfer mechanism, supported by quantitative spectral overlap analysis showing that 99.5% of the PNC photoluminescence falls within the 450–575 nm EQE enhancement window and that the maximum differential EQE gain occurs at 519 nm—only 2 nm from the PNC emission peak. Our results suggest that controlled PNC incorporation enables efficient optical energy coupling, leading to high-sensitivity, fast-response OPDs suitable for optical communication applications. Full article

In complex traffic environments such as low light, strong glare, occlusion and at night, systems that rely solely on visible light single sensors for pedestrian detection have drawbacks such as low detection accuracy and poor robustness. Based on the YOLOv8 convolutional network, this paper adopts a dual-branch structure to process visible light and infrared images simultaneously, fully utilizing feature information at different scales to effectively detect pedestrian targets in complex and changeable environments. To address the issues of insufficient interaction of modal feature information and fixed fusion weights, a cross-modal feature interaction and enhancement mechanism was introduced. A modal-channel interaction block (MCI-Block) was designed, in which residual connection structures and weight interaction were added within the module to achieve feature enhancement and filter out noise information. Introduce a dynamic weighted feature fusion strategy, adaptively adjusting the contribution ratio of different modal features in the fusion process, aiming to enhance the discrimination ability of the key pedestrian area. The training and testing of the network designed in this paper were completed on the visible light and infrared pedestrian detection dataset LLVIP and Kaist. At the same time, the test results of the dual-branch model and the model designed in this paper were further verified in actual traffic scenarios. The results show that the dual-branch YOLOv8 network for visible light and infrared images, which was constructed in this paper, can reliably enhance the detection performance of pedestrian targets in complex traffic environments, including accuracy, recall rate, and mAP@0.5, etc., thereby improving the robustness of pedestrian detection. Full article

Atmospheric laser beam propagation is typically perturbed by the dual influences of aerosol particle systems and atmospheric turbulence. This joint perturbation induces intensity fluctuations in the transmitted optical field, which significantly degrades the performance of laser-based systems. This study integrates and improves upon existing simulation algorithms, establishing a coupled model that combines the Monte Carlo method and multi-phase screens. The model accurately characterizes optical field evolution and reveals that the impacts of scattering and turbulence on the scintillation index (SI) are not simply additive: turbulence perturbation enhances intensity fluctuations, leading to an increase in SI; however, as the energy proportion of scattered light rises, its statistical stationarity begins to dominate the optical field characteristics, stabilizing SI. Based on radiative transfer and Mie scattering theories, an analytical formula for single-scattering SI is derived, enabling direct calculation from fundamental parameters. Furthermore, a composite SI expression is established using the scattered-to-transmitted light intensity ratio. To address model deviations along the dimensions of visibility and turbulence strength, a sinusoidal compensation model and a logarithmic compensation model are proposed, respectively. Validation results verify the complementary and competitive mechanisms of scattering and turbulence in modulating intensity fluctuations. This research provides efficient theoretical tools and practical references for simulating and optimizing laser transmission in complex atmospheric environments. Full article

The development of efficient, stable, and sustainably fabricated photocatalysts for solar-driven hydrogen evolution remains a critical challenge in the field. Herein, we report a novel green coprecipitation strategy to synthesize calcium-doped zinc oxide (Ca-ZnO) nanosheets, utilizing cactus juice as a natural, multifunctional medium for the coprecipitation process. This method enables the in situ, tunable incorporation of 3–7% Ca²⁺ ions into the wurtzite ZnO lattice without the use of harsh chemical reagents. Comprehensive characterization confirms that Ca²⁺ substitutionally replaces Zn²⁺, which preserves the intrinsic crystal structure of ZnO well while inducing the formation of uniform nanosheet morphology. This doping strategy effectively modulates the electronic band structure, progressively narrowing the bandgap from 3.19 eV to 2.90 eV and significantly enhancing visible-light absorption. Crucially, the incorporation of Ca²⁺ also generates oxygen vacancies, which serve as efficient electron traps to suppress photogenerated charge carrier recombination. The optimized 5%Ca-ZnO photocatalyst demonstrates a favorable hydrogen evolution rate of 889 μmol·g⁻¹·h⁻¹ under full-spectrum irradiation, with stability, retaining 94.8% of its activity after four cycles. This work not only provides a high-performance material but also establishes a generalizable, sustainable paradigm for the design of advanced semiconductor photocatalysts. Full article

Non-orthogonal multiple access (NOMA) has been recognized as a promising technique to alleviate the bandwidth limitation in visible light communication (VLC) downlinks. Nevertheless, the corresponding power allocation problem is typically non-convex and computationally challenging under practical system constraints, which limits the effectiveness of conventional optimization approaches. To address this issue, this paper proposes an improved particle swarm optimization (IPSO)-based strategy that aims at maximizing the system sum rate and employs adaptive mechanisms including an adaptive dynamic inertia weight, cooperative evolutionary learning factors, and enhanced elite opposition-based learning (EEOBL) to strengthen both global search capability and convergence performance. Simulation results indicate that the proposed scheme significantly improves the overall system capacity across diverse interference scenarios, while achieving accelerated convergence and enhanced robustness. Full article

We develop Cs_xFA_1−xPbI₃ perovskite photodetectors with varying Cs content in the x = 0.05–0.25 range to identify the most stable cubic-lattice perovskite composition for visible-light photodetection. The perovskite layers were deposited by the spin-coating technique on a nickel oxide p-type contact and then were covered with C₆₀/Ag electron contact to obtain a vertical pin diode structure. X-ray diffraction (XRD) and scanning electron microscopy (SEM) measurements show that x = 0.1–0.2 provides the most stable lattice and pinhole-free perovskite layers. The photocurrents are linear in an extremely wide 1 nW–10 mW excitation power range, providing photoresponsivity of 0.28 A/W at 532 nm (green light), similar to that of Si photodiodes. The testing of the photodetectors using picosecond pulses provided their rise times and fall times. The x = 0.2 composition provided the shortest rise time values of 27.5 ns, leading to a detector modulation bandwidth of 12.7 MHz. This indicates that this perovskite composition is suitable for replacing silicon photodetectors in cost-efficient light detection systems for imaging and light communication applications such as Li-Fi. Full article

Photoresponsive hydrogen-bonded azo-macrocycles capable of selectively recognizing lithium cation were constructed by reversing the amide–azobenzene connectivity, which redistributes electron density and preorganizes four carbonyl oxygen donors into a smaller, more convergent cavity. Compared with a connectivity-isomeric reference macrocycle, the new receptor displays a pronounced preference for Li⁺, in which complexation with LiClO₄ shows a slow exchange on the ¹H NMR timescale and an association constant (K_a) exceeding 10⁴ M⁻¹, whereas the reference binds Li⁺ weakly (<5 M⁻¹). In contrast, both hosts exhibit only modest binding toward Na⁺ (10²~10³ M⁻¹) and fast exchange, consistent with size/geometry matching of the compressed cavity to Li⁺. The newly designed azo-macrocycles reveal a highly selective recognition of Li⁺ thanks to the more evenly arrayed four amide oxygens enclosing a cavity of small dimension. Notably, E/Z photoisomerization of macrocycle switches the binding regime, enabling reversibly light-triggered Li⁺ binding under UV irradiation and recapture under visible light. This work establishes a new photoresponsive receptor based on H-bonded azo-macrocycles for photoswitchable recognition of Li⁺. Full article

Simultaneous hydrogen fuel and value-added chemical production from renewable resources is a key strategy in sustainable catalysis. This work presents a novel strategy employing metal–organic frameworks (MOFs) as precursors for synthesizing advanced titanium dioxide (TiO₂) photocatalysts with enhanced structural and optical properties. Two photocatalysts, M-BDC and M-2,5PDC, were synthesized via controlled calcination of MIL-125(Ti) using terephthalic and 2,5-pyridinedicarboxylic acids, respectively. Characterization confirmed the formation of mixed anatase/rutile TiO₂ phases with mesoporous structures. Notably, nitrogen incorporation in M-2,5PDC reduced the optical band gap to 2.94 eV compared with 3.08 eV for M-BDC, enhancing visible-light absorption. Photocatalytic experiments conducted at near-neutral pH (6.0) demonstrated effective simultaneous glycerol oxidation and hydrogen evolution without the use of alkaline additives. M-BDC achieved 30% glycerol conversion with 78.85% selectivity toward dihydroxyacetone and 21.15% toward glyceraldehyde, while M-2,5PDC exhibited selectivities of 71.55% and 28.45%, respectively. Glycerol underwent partial oxidation without complete mineralization, generating high-value products in parallel with hydrogen production. Both catalysts displayed excellent reuse stability across three consecutive cycles, with M-BDC showing enhanced dihydroxyacetone selectivity (78.85% to 84.42% between cycles). This MOF-derived TiO₂ platform integrates controlled synthesis, near-neutral pH operation, high selectivity, and catalytic stability, thereby establishing a viable strategy for the simultaneous production of clean fuel and value-added chemicals from renewable resources. Full article

Images captured in low-light conditions often have poor visibility, low contrast, and color distortion due to uneven lighting. Most existing enhancement methods often suffer from unstable brightness recovery and color cast, which affect both visual quality and performance of advanced vision tasks. To address those issues, we propose DADNet, a dual-branch network with an attention mechanism and dark channel prior containing an Illumination Enhancement Module (IEM) and Color Transformation Module (CTM). The IEM extracts multi-scale features and improves lighting based on the dark channel prior, while the CTM employs the attention mechanism to handle color features and adjust saturation adaptively. Experimental results on three datasets show that DADNet performs well in both qualitative and quantitative evaluations. It effectively preserves image structure and texture details while achieving a good balance between overall brightness and color quality. Full article

Metal–organic frameworks (MOFs) are unique microporous materials being explored for a wide range of applications. Their porosity and high surface areas can readily be exploited for guest–host interactions, separations, and photochemical catalysis, but many suffer from poor charge separation and fast electron–hole recombination. Introducing structural defects, such as missing linkers or metal nodes, can create unsaturated metal sites and alter band structure, conductivity, and light absorption, improving photocatalytic performance. UiO-66-NH₂ and MIL-125-NH₂ are water-stable, visible-light-absorbing MOFs well suited for photocatalytic degradation of organic dyes. In this work, the influence of defect engineering on photocatalytic properties of MOFs was investigated using formic and acetic acid modulators with UiO-66-NH₂ and variable temperature with MIL-125-NH₂ during synthesis. The resulting materials were characterized by XRD, FTIR and SEM/EDS. Defect states were tracked using N₂ adsorption/BET analysis and UV–Vis spectroscopy. Photocatalytic activity was evaluated by monitoring Rhodamine B (RhB) degradation in aqueous solution under simulated solar irradiation. It was found that increased temperature beyond 120 °C during synthesis promotes mesopore formation and decreases the bandgap in MIL-125-NH₂, resulting in a more photoactive material. Defective MIL-125-NH₂ synthesized at 150 °C showed the most defects and proved to be the best photocatalyst investigated in this study. Formic acid modulation in UiO-66-NH₂ generated smaller crystallites that slightly increased the bandgap; however, the surface area decreased proportionally with the amount of formic acid used. The decreased surface area and observed enhancement in photocatalytic degradation of RhB suggest that formic acid introduces defects into the UiO-66-NH₂ framework that enhance photocatalytic properties. UiO-66-NH₂ treated with acetic acid resulted in larger crystals, increased bandgaps, and increased surface areas, suggesting that acetic acid simply modulates growth rather than imparting defects to the framework. Full article

Low-light image enhancement (LLIE) remains challenging due to severe degradation of high-frequency structures and semantic ambiguity under extreme darkness. Although existing methods achieve satisfactory brightness recovery, they often suffer from structural inconsistency and semantic drift, as diverse scenes are typically processed with uniform enhancement strategies or static text prompts. To address these issues, we propose a Multi-Modal Structural and Semantic-Adaptive Network (MSSA-Net) under a structure-anchored paradigm. First, we design a Multi-Scale Self-Refinement Block (MSRB) to enhance degraded visible representations through multi-scale feature extraction and progressive refinement. Meanwhile, a pseudo-infrared structural prior derived from the input image is introduced to provide noise-insensitive geometric cues. These cues are extracted via a Structure-Guided Cross-Attention (SGCA) module to produce structure-dominant features. The refined visible features and structural features are then adaptively integrated through an adaptive residual fusion (ARF) module to achieve balanced restoration. Furthermore, we develop a Large Multi-modal Model (LMM)-Driven Scene-Adaptive Attention mechanism that generates instance-aware scene tags from a coarse preview and injects semantic embeddings into visual features. Extensive experiments demonstrate that MSSA-Net improves structural fidelity, brightness recovery, and semantic naturalness across multiple benchmarks. Full article