Search Results (1,071)

This study presents the synthesis and comprehensive characterization of tin dioxide nanoparticles (SnO₂NPs). SnO₂NPs were obtained using a conventional wet-chemistry route and an environmentally friendly green-chemistry approach employing plant extracts from rooibos leaves (Aspalathus linearis), pomegranate seeds (Punica granatum), and kiwifruit peels (family Actinidiaceae). The thermal stability and decomposition profiles were analyzed by thermogravimetric analysis (TGA), while their structural and physicochemical properties were investigated using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), ultraviolet–visible (UV–Vis) spectroscopy, dynamic light scattering (DLS), Raman spectroscopy, and attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy. Transmission electron microscopy (TEM) confirmed the nanoscale morphology and uniformity of the obtained particles. The photocatalytic activity of SnO₂NPs was evaluated via the degradation of methyl orange (MeO) under UV irradiation, revealing that nanoparticles synthesized using rooibos extract exhibited the highest efficiency (68% degradation within 180 min). Furthermore, surface-enhanced Raman scattering (SERS) spectroscopy was employed to study the adsorption behavior of L-phenylalanine (L-Phe) on the SnO₂NP surface. To the best of our knowledge, this is the first report demonstrating the use of pure SnO₂ nanoparticles as SERS substrates for biologically active, low-symmetry molecules. The calculated enhancement factor (EF) reached up to two orders of magnitude (10²), comparable to other transition metal-based nanostructures. These findings highlight the potential of SnO₂NPs as multifunctional materials for biomedical and sensing applications, bridging nanotechnology and regenerative medicine. Full article

In this paper, selected methods for the statistical assessment of distribution parameters using estimators were briefly described. Selected aspects of the theory of measurement uncertainty, the determination of standard uncertainty of type A, type B, total and expanded were discussed. The structure of the “current—polarization-dependent loss” optical fiber sensor is presented, which can be used to measure current in power lines. The method of measuring polarizing attenuation using an optical reflectometer OTDR is discussed. The results of research deal with the influence of the light wave, optical fiber length and the angle of rotation of the plane of polarization (polarization angle) on the value of polarizing attenuation are presented. Conclusions from the experiment were formulated regarding the selection of optical fiber and optical window so that the polarization angle was within a specific interval. Full article

Climate change or even the natural occurrence of periods of low suitability for the production of forage species are obstacles to maintaining adequate animal nutrition. Indoor green fodder production is an alternative to this problem; however, advances in technologies capable of improving this system still need to be studied in depth. The objective of this study was to evaluate the qualitative and quantitative characteristics of hydroponic green fodder production of millet and sorghum under varying monochromatic light supplementation and nicotinamide application. Eight treatments were defined by lighting (LS—Led Full Spectrum; LS + Ultraviolet LED; LS + Red LED; LS + Blue LED), and combined with the application of nicotinamide (with and without) at a concentration of 200 mg L⁻¹. Cultivation under conditions of light supplementation with UV radiation or monochromatic lights results in increased light intensity by modifying the wavelength spectrum received by the plant, modification of the quality of photons received in relation to the energy level that leads to luminous stress and, consequently, lower green fodder development concerning height and fresh mass. Nicotinamide acts as a bioprotectant, attenuating the stressful effects and enabling greater productive efficiency in the production of hydroponic green fodder, particularly in vertical cultivation, which provides increased height and fresh mass for millet and sorghum green fodder. In contrast, the stress resulting from light supplementation can be used as a tool to increase carotenoid levels in plants and may be indicated for production systems that have this objective for biofortification of forages with bioactives with antioxidant effects. Full article

Non-geniculate crustose coralline algae (NCA) are important in algal reef ecosystems, yet their physiological responses to turbidity and sediment burial remain insufficiently understood. We examined how six turbidity levels (0–300 mg L⁻¹) and four sediment deposition depths (0–3 cm) affected two dominant species, Sporolithon sp. and Phymatolithon sp. Under turbidity treatments, for Sporolithon sp., Fv/Fm was lowest at 0 mg L⁻¹ (0.43 ± 0.01) and highest at 250 mg L⁻¹ (0.62 ± 0.01). ETRmax increased markedly under 150 mg L⁻¹ (17.94 ± 0.27) but declined under 300 mg L⁻¹ (5.33 ± 0.19). In Phymatolithon sp., turbidity levels of 150–250 mg L⁻¹ produced consistently higher Fv/Fm values (0.58–0.60) and the lowest ETRmax occurred at 300 mg L⁻¹ (5.71 ± 0.34). Sediment burial caused strong early reductions in photosynthetic performance. In Sporolithon sp., all burial depths except 0 cm caused significant Fv/Fm declines within five days (decrease to 0.46). After 45 days, ETRmax ranged from 9.28 ± 0.38 at 0 cm to 4.02 ± 0.11 at 3 cm, with intermediate values at 1 and 2 cm. Phymatolithon sp. showed rapid declines in Fv/Fm at all depths (1 to 3 cm) before partial recovery after 15–20 days. Overall, moderate turbidity (150–250 mg L⁻¹) provided protective light attenuation, whereas sediment deposition imposed strong early physiological stress. The contrasting responses of the two species highlight different adaptive strategies for surviving low-light and sediment-rich environments. Full article

The development of minimally invasive diagnostic devices in the biomedical field has grown significantly, especially those that take advantage of photoacoustic phenomena. Photoacoustic imaging is an imaging technique that exploits the photoacoustic effect, relying on the conversion of absorbed light into ultrasound waves. Thanks to lab-on-fiber technology, optical fiber can be functionalized to generate and receive a photoacoustic signal. Weak acoustic signals often limit this process, as conversion efficiency can be influenced by factors such as tissue heterogeneity, light scattering, and the attenuation of the acoustic waves within tissues. Consequently, there is significant interest in the development of highly sensitive systems with broad bandwidths. While the literature has largely focused on standard devices utilizing the interferometric effect in homogeneous slabs, this study explores the potential of multilayer structures that leverage Bragg reflection to be realized on the fiber tip. We numerically investigated both periodic and aperiodic designs of polymeric multilayer structures to further enhance the optical performance of opto-acoustic sensors. We demonstrate an enhancement in sensitivity of up to about three orders of magnitude without compromising bandwidth. This work highlights the advantages of multilayer sensor designs in improving sensitivity and performance for high-frequency opto-acoustic sensing. Full article

We investigate crosstalk effects in a dual-modality tactile–proximity sensing system based on Time-of-Flight (ToF) technology integrated within a flat poly(methyl methacrylate) (PMMA) light guide. Building on the OptoSkin framework, we employ two commercially available TMF8828 multi-zone ToF sensors, one configured for tactile detection via frustrated total internal reflection (FTIR) and the other for external proximity measurements through the same transparent substrate. Controlled experiments were conducted using a 2 cm² silicone pad for tactile interaction and an A4-sized diffuse white target for proximity detection. Additional measurements with a movable PMMA sheet were performed to quantify signal attenuation, peak broadening, and confidence degradation under transparent-substrate conditions. The results demonstrate that the TMF8828 can simultaneously resolve both contact-induced scattering and distant reflections, but that localized interference zones occur when sensor fields of view overlap within the substrate. Histogram analysis reveals the underlying multi-path contributions, providing diagnostic insight not available from black-box ToF devices. These findings highlight both the opportunities and limitations of integrating multiple ToF sensors into transparent waveguides and inform design strategies for scalable robotic skins, wearable interfaces, and multi-modal human–machine interaction systems. Full article

Visible light positioning (VLP) has emerged as a promising indoor positioning technology, owing to its high accuracy and cost-effectiveness. In practical scenarios, signal attenuation, multiple light reflections, or light-deficient regions, particularly near room corners or furniture, can significantly degrade the light quality. In addition, the non-uniform light distribution by light-emitting diode (LED) luminaires can also introduce errors in VLP estimation. To mitigate these challenges, recent studies have increasingly explored the use of machine learning (ML) techniques to model the complex nonlinear characteristics of indoor optical channels and improve VLP performance. Convolutional neural networks (CNNs) have demonstrated strong potential in reducing positioning errors and improving system robustness under non-ideal lighting conditions. However, the performance of CNN-based systems is highly sensitive to their hyperparameters, including learning rate, dropout rate, batch size, and optimizer selection. Manual tuning of these parameters is not only time-consuming but also often suboptimal, particularly when models are applied to new or dynamic environments. Therefore, there is a growing need for automated optimization techniques that can adaptively determine optimal model configurations for VLP tasks. In this work, we propose and demonstrate a VLP system that integrates received signal strength (RSS) signal pre-processing, a CNN, and particle swarm optimization (PSO) for automated hyperparameter tuning. In the proof-of-concept VLP experiment, three different height layer planes (i.e., 200, 225, and 250 cm) are employed for the comparison of three different ML models, including linear regression (LR), an artificial neural network (ANN), and a CNN. For instance, the mean positioning error of a CNN + pre-processing model at the 200 cm receiver (Rx)-plane reduces from 9.83 cm to 5.72 cm. This represents an improvement of 41.81%. By employing a CNN + pre-processing + PSO, the mean error can be further reduced to 4.93 cm. These findings demonstrate that integrating PSO-based hyperparameter tuning with a CNN and RSS pre-processing significantly enhances positioning accuracy, reliability, and model robustness. This approach offers a scalable and effective solution for real-world indoor positioning applications in smart buildings and Internet of Things (IoT) environments. Full article

Chronic exposure to short-wavelength blue light induces oxidative stress, inflammation, and apoptosis in retinal tissues, contributing to vision loss. This study investigated the protective effects of Lactobacillus reuteri Y7, a human-derived probiotic, against blue light–induced retinal damage in mice. Male C57BL/6 mice were exposed to 400 lux blue light for 35 days and received either low- or high-dose Y7, lutein, or no intervention. Retinal morphology, inflammatory gene expression, gut barrier integrity, and gut microbiota composition were assessed. Low-dose Y7 promoted microbial diversity and enrichment of short-chain fatty acid–producing taxa, while high-dose Y7 favored enrichment of Akkermansia, Parasutterella, and Bacteroides, enhancing mucosal barrier function and metabolic regulation. Both doses attenuated retinal inflammation, preserved retinal layers, and improved gut barrier integrity, with high-dose Y7 matching or exceeding lutein’s protective effects. Mechanistic insights suggest a gut–retina axis whereby microbial metabolites modulate oxidative stress, inflammation, and vascular homeostasis. These findings highlight L. reuteri Y7 as a potential non-invasive strategy for retinal degeneration prevention, with efficacy comparable to dietary antioxidants. Future studies should explore long-term safety, metabolite-mediated mechanisms, and comparative efficacy with other antioxidants. Full article

Underwater images often suffer from color distortion, reduced contrast, and blurred details due to the selective absorption and scattering of light by water, which limits the performance of underwater visual tasks. To address these issues, this paper proposes an underwater image enhancement method that integrates multi-channel attenuation analysis and discrete cosine transform (DCT). First, the color statistics of an in situ-captured underwater image are mapped to those of a reference image selected from a well-illuminated natural image dataset with standard color distribution; no pristine underwater image is required. This mapping yields a color transfer image, i.e., an intermediate color-corrected result obtained via statistical matching. Subsequently, this image is fused with an attenuation weight map and the original input to produce the final color-corrected result. Secondly, taking advantage of the median’s resistance to extreme value interference and the Sigmoid function’s flexible control of gray-scale transformation, the gray-scale range is adjusted in different regions through nonlinear mapping to achieve global contrast balance. Finally, considering the visual system’s sensitivity to high-frequency details, a saliency map is extracted using Gabor filtering, and the frequency characteristics are analyzed through block DCT transformation. Adaptive gain is applied to high-frequency details to enhance them. Experiments were conducted on the UIEB, EUVP, and LSUI datasets and compared with existing methods. Through qualitative and quantitative analysis, it was verified that the proposed algorithm not only effectively enhances underwater images but also significantly improves image clarity. Full article

Accurate depth estimation is fundamental for underwater applications such as robotics and marine exploration. However, underwater imaging suffers from severe degradation due to light attenuation, scattering, and geometric distortion, which is compounded by the scarcity of real stereo data. To address these challenges, we propose Joint Dual-Branch Denoising (JDBD), which is a plug-in framework embedded within dual-branch depth estimation networks. JDBD performs task-aware denoising via bidirectional refinement between a monocular and a stereo pathway: the monocular branch combines Adaptive White Balance and a Red Inverse Channel Prior for color correction and haze suppression, while the stereo branch applies Joint Bilateral Filtering to reduce scattering and preserve edges. Trained on the synthetic UWStereo dataset and evaluated on the real-world SQUID dataset as well as a subset of UWStereo, JDBD achieves high depth estimation accuracy and visual fidelity in underwater scenes, demonstrating robust and adaptable performance across diverse conditions. Full article

Next-generation photonic memory, leveraging broad spectral operability and electromagnetic immunity, enables ultrafast data storage with high density, overcoming the physical limitations of silicon-based electronic memory in the post-Moore era. Phase-change materials (PCMs) are particularly promising for photonic memory due to their exceptional optical contrast between amorphous and crystalline states. Furthermore, photonic phase-change memory can be deployed as tunable components (such as optical attenuators and delay lines) within reconfigurable integrated photonic systems for telecommunications and computing. Here, we optimize the thickness of PCM cells to maximize crystalline-state light absorption and enhance transmission contrast. The resulting photonic memory achieves outstanding performance: ultralow-energy programming (0.96 pJ/operation), 9 fJ detection sensitivity, >10⁵ s retention, 6000-cycle endurance, and multi-level storage capacity (209 distinct states). Furthermore, by structuring the PCM into a micro-cylinder array atop a PCM film, we achieve stable transmission contrast through 2 × 10⁶ cycles—far exceeding the durability of single-cell structures—and an 8.69 dB improvement in contrast over film-free micro-cylinder arrays. These advances highlight the critical role of microstructural optimization in enabling high-performance, on-chip photonic memory for future integrated photonic telecommunication and computing systems. Full article

Fungal polysaccharides represent a structurally diverse group of bioactive compounds with increasing recognition for their hepatoprotective potential. This review synthesizes current evidence on their roles in the prevention and treatment of liver diseases, including alcohol-related liver disease (ALD), metabolic dysfunction-associated fatty liver disease (MAFLD), or toxin-induced injury. The analyzed studies demonstrate that polysaccharides isolated from species such as Lentinula edodes, Grifola frondosa, Ganoderma lucidum, Coriolus versicolor, and Cordyceps militaris exert beneficial effects by reducing oxidative stress, attenuating inflammation, and improving metabolic homeostasis. Mechanistically, these effects are mediated through the regulation of multiple signaling pathways, including Nuclear Factor kappa-light-chain-enhancer of activated B cells (NF-κB), Nuclear factor erythroid 2–related factor 2 (Nrf2), and NOD-like receptor protein 3 (NLRP3) inflammasome, as well as modulation of gut microbiota. Fungal polysaccharides were also shown to improve hepatic function by lowering serum biomarkers of liver injury and ameliorating histopathological damage. Presented evidence indicates that fungal polysaccharides possess considerable potential as multifunctional hepatoprotective agents, highlighting the need for further mechanistic insight and clinical validation. Full article

Minimally Invasive Surgery is often limited by the lack of tactile feedback. Indeed, surgeons have traditionally relied heavily on tactile feedback to estimate tissue stiffness - a critical factor in both diagnostics and treatment. With this in mind we present in this paper a flexible sensor foil, based on polymer optical waveguide. This sensor has been applied for real-time contact force measurement, material stiffness differentiation and surface texture reconstruction. Interrogated by a commercially available optoelectronic device, the sensor foil offers precise and reproducible feedback of contact forces up to 5 N, with a minimal detectable limit of 0.1 N. It also demonstrates distinct optical attenuation responses when indenting silicone samples of varying stiffnesses under controlled displacement. When integrated onto a 3D-printed module resembling an endoscopic camera and manipulated by a robotic arm, the sensor successfully generated spatial stiffness mapsof a phantom. Moreover, by sliding over structures with varying surface textures, the sensor foil was able to reconstruct surface profiles based on the light attenuation responses. The results demonstrate that the presented sensor foil possesses great potential for surgical applications by providing additional haptic information to surgeons. Full article

Objective: Previous reports showed that periodontopathic bacteria induce epithelial–mesenchymal transition (EMT) in oral squamous cell carcinoma (OSCC). Fisetin, a foodborne flavonoid, is reportedly associated with anticancer potential in various carcinogenic processes. This study aimed to elucidate the effects of fisetin on Fusobacterium nucleatum- and Porphyromonas gingivalis-induced EMT in OSCC cells. Methods: OSCC cells were co-cultured with live and heat-killed forms of F. nucleatum and P. gingivalis. The concentration of fisetin was set at 10 μM. Morphological changes in the OSCC cells were observed under a light microscope. Cell viability was measured using the Cell Counting Kit-8 assay, whereas migration was examined via wound healing. The mRNA expression of EMT-related markers was quantified using quantitative real-time polymerase chain reaction (PCR), and the expression of EMT-related markers and Wnt pathway-associated proteins was examined via Western blotting. Results: At a multiplicity of infection (MOI) of 300:1 for F. nucleatum and 100:1 for P. gingivalis, OSCC cell viability remained unchanged; however, wound closure rates increased significantly relative to the control. Likewise, treatment with fisetin (10 µM) did not materially alter viability; nevertheless, it attenuated promigratory effects induced by heat-killed periodontal pathogens at 3 h and 6 h. The OSCC cells exhibited EMT-like morphological changes after 6 h of co-culture with heat-killed pathogens. Consistently, reverse-transcriptase quantitative PCR and Western blot analyses showed increased expression of TWIST, ZEB1, and N-cadherin, accompanied by decreased E-cadherin expression, which was more pronounced in F. nucleatum than in P. gingivalis. However, fisetin reversed these trends. Moreover, co-culture with heat-killed pathogens markedly elevated β-catenin protein levels. In line with modulation of canonical Wnt/β-catenin signaling, fisetin and a Wnt inhibitor reduced β-catenin expression, whereas co-treatment with a Wnt agonist restored β-catenin levels in the presence of fisetin. Conclusions: Heat-killed F. nucleatum and P. gingivalis induced EMT in OSCC cells, with F. nucleatum exerting the strongest effect. Fisetin suppressed pathogen-driven EMT, at least partly via canonical Wnt/β-catenin signaling, highlighting its potential therapeutic value and warranting further investigation. Full article

The transportation of large murals with significant historical and cultural value presents a considerable challenge due to their high susceptibility to damage caused by mechanical vibrations. This article presents a study on the design, implementation, and evaluation of an advanced wire rope isolator system, complemented by vibration sensors equipped with indicator lights for real-time monitoring. The research focuses on the case study of the relocation of Diego Rivera’s mural “Pan American Unity” from the City College of San Francisco to the San Francisco Museum of Modern Art (SFMOMA). The study observed a reduction in vibration transmission to the mural panels, achieving vibration attenuation of up to −20 dB in the critical 10–30 Hz frequency band during transportation. It was also found that the implementation of real-time monitoring with indicator lights alerted operators and conservators to critical vibration levels, enabling immediate intervention. Full article