Search Results (12,048)

High-purity quartz (HPQ) is a critical raw material for advanced technologies including semiconductors, photovoltaic cells, and optical fibers. This study reviews the geological occurrence, beneficiation routes, and strategic significance of HPQ within the European context. Quartz processing follows a sequential flowsheet of comminution, magnetic separation, flotation, acid leaching, and thermal treatment, designed to remove mineral impurities such as Fe, Al, Ti, and mica. The resulting ultra-high-purity quartz (UHPQ) achieves the chemical and physical specifications required for high-tech industries. Quartz, which is the most common mineral on Earth, can be found in a variety of geological locations such as granitic rocks and pegmatites in the Variscan Belt, metamorphic quartzites, hydrothermal veins, and Pleistocene periglacial and aeolian sediments. Case studies of European deposits demonstrate that geological origin directly influences processing requirements, and that tailored beneficiation strategies are essential to unlock viable resources. To our knowledge, this is the first Europe-focused synthesis that links these findings with the EU Critical Raw Materials Act, the work that emphasizes the potential for domestic HPQ development to strengthen European supply chain resilience, reduce dependence on imports, and support the transition to a green and digital economy. Full article

A multimode magneto-optical fiber based on Tb³⁺-containing borogermanate glass was designed, fabricated, and characterized, aiming at potential sensing applications. There are continuing challenges in the development of single-mode (SMF) or multimode (MMF) optical fibers doped with rare-earth (RE) ions and exhibiting high Verdet constants, related to devitrification of the precursor glass. Most RE-doped glass compositions are not suitable as precursors for core-cladding fiber production due to devitrification processes and consequent poor optical quality. Application as Faraday rotators is limited by the intrinsically low Verdet constant of silica (~0.589 rad T⁻¹ m⁻¹ at 1550 nm and 0.876 rad T⁻¹ m⁻¹ at 1310 nm). Borogermanate glasses are good candidates for manufacturing optical fibers due to their excellent potential to solubilize high concentrations of Tb³⁺ ions as well as satisfactory thermal stability. In this work, a magneto-optical core-cladding borogermanate fiber with a 227 μm diameter was fabricated, with characterization using differential scanning calorimetry (DSC), thermomechanical analysis (TMA), viscosity measurements, M-lines spectroscopy, UV-Vis-NIR absorption spectroscopy, the cut-back technique, and magneto-optical measurements. The measured numerical aperture (NA) was 0.183, with minimum attenuation of 13 dB m⁻¹ at 1270 nm. The Verdet constant (V_B) reached −6.74 rad T⁻¹ m⁻¹ at 1330 nm. Full article

The field of underwater image enhancement (UIE) has advanced significantly, yet it continues to grapple with persistent challenges stemming from complex, spatially varying optical degradations such as light absorption, scattering, and color distortion. These factors often impede the efficient deployment of enhancement models. Conventional approaches frequently rely on uniform processing strategies that neither adapt effectively to diverse degradation patterns nor adequately incorporate physical principles, resulting in a trade-off between enhancement quality and computational efficiency. To overcome these limitations, we propose a Dual-Path Physics-Guided Mamba Network (DPPGM), a lightweight framework designed to synergize physical optics modeling with data-driven learning. Extensive experiments on three benchmark datasets (UIEB, LSUI, and U45) demonstrate that DPPGM outperforms 13 state-of-the-art methods, achieving an exceptional balance with only 1.48 M parameters and 25.39 G FLOPs. The key to this performance is a symmetry-constrained architecture: it incorporates a dual-path Mamba module for degradation-aware processing, physics-guided optimization based on the Jaffe–McGlamery model, and compact subspace fusion, ensuring that quality and efficiency are mutually reinforced rather than competing objectives. Full article

Obtaining accurate information on stratigraphic conditions and drilling status is necessary to ensure the safety of the drilling process and to guarantee the production of oil and gas. Sensing while drilling and intelligent monitoring technology, which employ multiple sensors and involve the use of intelligent algorithms, can be used to collect downhole information in situ to ensure safe, reliable, and efficient drilling and mining operations. These approaches are characterized by effective sensing and comprehensive utilization of drilling information through the integration of multi-sensor signals and intelligent algorithms, a core component of machine learning. The article summarizes the current research status of domestic and international sensing while drilling and intelligent monitoring technology using systematically collected relevant information. Specifically, first, the drilling-sensing methods used for in situ acquisition of downhole information, including fiber-optic sensing, electronic-nose sensing, drilling engineering-parameter sensing, drilling mud-parameter sensing, drilling acoustic logging, drilling electromagnetic wave logging, and drilling seismic logging, are described. Next, the basic composition and development direction of each sensing technology are analyzed. Subsequently, the application of intelligent monitoring technology based on machine learning in various aspects of drilling- and mining-status identification, including bit wear monitoring, stuck drill real-time monitoring, well surge real-time monitoring, and real-time monitoring of oil and gas output, is introduced. Finally, the potential applications of sensing while drilling and intelligent monitoring technology in deep-earth, deep-sea, and deep-space contexts are discussed, and the challenges, constraints, and development trends are summarized. Full article

As the demand for high-speed space-borne data transmission grows, CubeSat-based Free-Space Optical Communication (FSOC) offers a viable solution for achieving a Gbps-speed optical intersatellite link on low-cost platforms. The Very-High-Speed Intersatellite Optical Link System Using an Infrared Optical Terminal and Nanosatellite (VISION) mission aims to establish these high-speed laser crosslinks, which require a precise pointing and relative positioning system at relative distances up to 1000 km. A real-time relative navigation system was developed based on dual-frequency GPS pseudorange and carrier-phase measurements, incorporating an adaptive Kalman filter which uses innovation-based covariance matching to dynamically adjust process noise covariance. Hardware-integrated testing with GPS signal generators and onboard receivers validated its performance under realistic conditions, consistently achieving sub-meter positioning accuracy across baselines up to 1000 km. An integrated orbit–attitude simulation further evaluated the feasibility of the Pointing, Acquisition, and Tracking (PAT) system by combining real-time relative navigation outputs with an attitude control system. Simulation results showed that the PAT system maintained a total pointing error of 274.3 μrad, sufficient to sustain stable high-speed optical links. This study demonstrates that the VISION relative navigation and pointing systems, integrated within the PAT framework, enable precise real-time optical intersatellite communication using CubeSats. Full article

Background: Idiopathic epiretinal membrane (iERM) is a common retinal pathology in elderly patients, thought to originate primarily from an anomalous process of posterior vitreous detachment. The standard treatment is pars plana vitrectomy (PPV) with membrane peeling. No consensus exists regarding the optimal timing of surgery, nor is it clear which patients are most likely to benefit. Given that iERM profoundly affects retinal vascular morphology and function, optical coherence tomography angiography (OCTA) has emerged as a valuable tool for identifying potential biomarkers. This systematic review aimed to synthesize the available evidence on OCTA-derived biomarkers and their correlations with visual function before and/or after surgical intervention in iERM, with a particular focus on their prognostic value for postoperative outcomes. Methods: A systematic search of PubMed/MEDLINE and Scopus was conducted on the 20th of May 2025 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Eligible studies included patients with iERM undergoing vitreoretinal surgery, used OCTA for pre- and/or postoperative assessment, investigated structure–function correlations, and were designed as clinical trials, observational studies, or case series with more than 10 patients. Exclusion criteria were studies with ≤10 cases, absence of separate iERM analysis, lack of surgical intervention, or non-English language. Data extraction covered study design, demographics, surgical approach, OCTA device, follow-up, OCTA biomarkers, and structure–function outcomes. Risk of bias in observational studies was assessed using the National Institute of Health (NIH) Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. Results: The search yielded 1053 records, of which 71 underwent full-text review and 43 met eligibility criteria. All included studies were observational, encompassing 1958 eyes from 1953 patients. The most frequently investigated biomarkers were the foveal avascular zone (FAZ) area and related parameters, vessel density (VD), and foveal density 300 (FD-300). Additional studies evaluated average vessel length (VL), blood flow area, vessel length density (VLD), vessel tortuosity (VT), fractal dimension (FD), and perfusion capacity (PC). Conclusions: By consolidating current evidence, this systematic review provides a comprehensive overview of structure–function correlations in iERM and highlights the potential of OCTA-derived metrics as biomarkers of disease severity and surgical prognosis. These findings help clarify underlying mechanisms of visual decline and establish the context for further research. Nonetheless, interpretation is limited by the observational design of all included studies and by heterogeneity in OCTA methodology and nomenclature, underscoring the need for standardization to improve comparability and foster greater coherence across studies. No funding was provided for this review. Full article

Training-free video summarization tackles the challenge of selecting the most informative keyframes from a video without relying on costly training or complex deep models. This work introduces C2FVS-DPP (Contextual Feature Fusion Video Summarization with Determinantal Point Process), a lightweight framework that generates concise video summaries by jointly modeling semantic importance, visual diversity, temporal structure, and {symmetry. The design centers on a symmetry-aware fusion strategy, where appearance, motion, and semantic cues are aligned in a unified embedding space, and on a reward-guided optimization logic that balances representativeness and diversity. Specifically, appearance features from ResNet-50, motion cues from optical flow, and semantic representations from BERT-encoded BLIP captions are fused into a contextual embedding. A Transformer encoder assigns importance scores, followed by shot boundary detection and K-Medoids clustering to identify candidate keyframes. These candidates are refined through a reward-based re-ranking mechanism that integrates semantic relevance, representativeness, and visual uniqueness, while a Determinantal Point Process (DPP) enforces globally diverse selection under a keyframe budget. To enable reliable evaluation, enhanced versions of the SumMe and TVSum50 datasets were curated to reduce redundancy and increase semantic density. On these curated benchmarks, C2FVS-DPP achieves F1-scores of 0.22 and 0.43 and fidelity scores of 0.16 and 0.40 on SumMe and TVSum50, respectively, surpassing existing models on both metrics. In terms of compression ratio, the framework records 0.9959 on SumMe and 0.9940 on TVSum50, remaining highly competitive with the best-reported values of 0.9981 and 0.9983. These results highlight the strength of C2FVS-DPP as an inference-driven, symmetry-aware, and resource-efficient solution for video summarization. Full article

Background/Objectives: Optical coherence tomography (OCT)-reflective drusen substructures (ODSs) are associated with the conversion of intermediate AMD to geographic atrophy (GA). However, ODSs must be manually identified, a laborious process introducing bias and variation. This study proposes objective radiomic metrics of drusen phenotypes and validates them for the prediction of GA development and GA growth rate. Methods: A total of 104 drusen with high-reflective cores (H-type), 105 with low-reflective cores (L-type), 129 conical drusen (C-type), and 101 normal drusen (N-type) were segmented from OCT images. Radiomic features were extracted from these drusen, and the most important features for drusen classification were extracted from the retinal pigment epithelium–Bruch’s membrane compartment of 743 OCT scans of eyes with dry AMD and used to predict GA conversion and fast growth. Results: Radiomic features classified drusen phenotypes with AUC = 0.87–0.95. H-type drusen have a higher reflectivity, greater variation in reflectivity, and coarser texture (p < 0.001). L-type drusen have a lower reflectivity and greater variation in reflectivity (p < 0.0001). C-type drusen have a less spherical shape and more disordered internal reflectivity (p < 0.001). N-type drusen have a more spherical shape and more uniform internal reflectivity (p < 0.001). These radiomic features predict the conversion from intermediate AMD to GA and top-quartile GA growth rate with AUC = 0.59–0.74 at years 1–3. Conclusions: These results demonstrate the potential of clinical phenotype-grounded radiomics for objective automated drusen analysis, GA risk stratification, and clinical prediction. Full article

The demand for high-performance polypropylene (PP) films in high-end packaging applications has been growing rapidly. However, Traditional polypropylene (PP) films are limited in application by their inadequate mechanical strength, heat-sealing performance, and matte properties. Hence, in this study, styrene-butadiene copolymer-modified polypropylene (PP) matte films using styrene-butadiene copolymer (SB) as a modifier were successfully prepared. A comprehensive characterization of the films’ optical, mechanical, thermal, and processing properties was conducted using specialized instrumentation. Capillary rheometry revealed that the melt viscosity of the PP/SB blends decreased with increasing shear rate, demonstrating typical pseudoplastic behavior. Differential scanning calorimetry (DSC) showed single melting and crystallization peaks, indicating excellent compatibility between PP and SB. The optimal performance was achieved with 7.00 wt% SB, resulting in a film with a light transmittance of 92.08%, a haze of 66.40%, and a gloss of 3.63 GU. This formulation also yielded more uniform tensile strength and elongation in both longitudinal and transverse directions, and reduced the heat-sealing temperature to 101 °C, significantly lower than the 111 °C required for pure PP. Overall, the SB-modified PP films exhibited excellent mechanical strength, enhanced heat sealability, and superior matte properties, highlighting their significant potential for high-end packaging applications. Full article

The thermal and optical properties of aqueous dispersions of magnetite nanoparticles were studied by dual-beam thermal-lens spectrometry. Surface-modified magnetite nanoparticles with an average crystal size of 7.5 nm were synthesized by a simple, one-stage method of coprecipitation followed by surface functionalization. For this purpose, the most popular and promising modifiers based on surfactants, polyelectrolytes, biopolymers and organic acids were used. The effect of the concentration of nanoparticles (in the range from 0.01 to 5 mg/L) and the nature of the surface modifier on the thermal diffusivity of the dispersion was studied. It was found that at concentrations of 0.4–0.6 mg/L, the dispersions exhibit heat-accumulating properties, which may be promising in the development of a magnetically controlled heat-conducting liquid. Thermal lens spectrometry in the steady-state measurement mode was used to reveal the processes of deposition and adsorption of magnetite nanoparticles on the surface of a quartz cell, leading to an apparent increase in thermal diffusivity by more than 30%. The paper touches upon the issues of accuracy and precision of temperature diffusion measurements, processing, and presentation of measurement results of time-resolved transient and steady-state signals for dispersed systems. The ratio of the change in the steady-state thermal-lens signals to the change in concentration regarding the concentration (dϑ/dc vs. c) provides a way to identify a systematic error at a low level (less than 5%) of thermal-lens measurements caused by a high concentration (or optical absorption) of the object. Various options for signal normalization (in terms of power, absorbance, and pure-solvent signal) are considered, and their advantages and disadvantages are discussed. An approach to using thermal diffusivity as a function of the steady-state signal of the sample is proposed. This approach allows for a comparative thermal-lens analysis of objects with different optical and thermal properties. Full article

Coastal lagoons are fragile and dynamic ecosystems that are particularly vulnerable to climate change and anthropogenic pressures such as urbanization and eutrophication. These vulnerabilities highlight the need for frequent and spatially extensive monitoring of water quality (WQ). While satellite remote sensing offers a valuable tool to support this effort, the optical complexity and shallow depths of lagoons pose major challenges for retrieving water column biogeochemical parameters such as chlorophyll-a ([chl-a]) and suspended particulate matter ([SPM]) concentrations. In this study, we develop and evaluate a robust satellite-based processing chain using Sentinel-2 MSI imagery over two French Mediterranean lagoon systems (Berre and Thau), supported by extensive in situ radiometric and biogeochemical datasets. Our approach includes the following: (i) a comparative assessment of six atmospheric correction (AC) processors, (ii) the development of an Optically Shallow Water Probability Algorithm (OSWPA), a new semi-empirical algorithm to estimate the probability of bottom contamination (BC), and (iii) the evaluation of several [chl-a] and [SPM] inversion algorithms. Results show that the Sen2Cor AC processor combined with a near-infrared similarity correction (NIR-SC) yields relative errors below 30% across all bands for retrieving remote-sensing reflectance R_rs(λ). OSWPA provides a spatially continuous and physically consistent alternative to binary BC masks. A new [chl-a] algorithm based on a near-infrared/blue R_rs ratio improves the retrieval accuracy while the 705 nm band appears to be the most suitable for retrieving [SPM] in optically shallow lagoons. This processing chain enables high-resolution WQ monitoring of two coastal lagoon systems and supports future large-scale assessments of ecological trends under increasing climate and anthropogenic stress. Full article

The conventional kinesin (kinesin-1) molecular motor is a prototypical member of the kinesin superfamily. It can processively step on microtubules toward the plus end by hydrolyzing ATP molecules, performing the biological function of shuttling cargos in cells. Its dynamics have been thoroughly studied using various methods including biochemical measurement, single molecule imaging, single molecule optical trapping, and so on. While most of the experiments yielded consistent results on the dynamics of the motor, a lot of conflicting experimental results have also been presented. Here, a brief review is given of the diverse conflicting experimental results. Furthermore, a model for the chemomechanical coupling of the motor is briefly reviewed, which can consistently and quantitatively explain these conflicting experimental results in addition to the other experimental results. A consistent explanation of the diverse conflicting experimental results with the same model is an essential criterion for determining the correctness of the model. Full article

Standard heat treatments for metals of a particular composition are typically designed with the assumption of a conventional starting microstructure, such as that produced by casting or wrought processing. When applied to metals fabricated by Laser Powder Bed Fusion (LPBF) metal additive manufacturing (AM), these heat treatments can produce inconsistent performance due to the unique as-built microstructures. This study investigates how modifications to standard heat treatments for 17-4 PH steel influence the microstructure and mechanical properties of LPBF-fabricated material. Specimens were produced and subjected to varying solutionizing and homogenizing treatments followed by standard aging treatments. Microstructures were characterized using optical microscopy, Electron Backscatter Diffraction (EBSD), and X-ray diffraction (XRD), and mechanical properties were evaluated through uniaxial tensile testing. Based on these results, recommendations are provided for achieving improved wrought-like performance in LPBF 17-4 PH steel. Full article

In this paper, we demonstrated a high-sensitivity polarization image sensor for millimeter-wave electric field imaging using electro-optic crystals. We developed a three-layer on-pixel polarizer structure fabricated with a 0.35-µm standard CMOS process, achieving an extinction ratio of 5.7, which corresponds to a 73% improvement over previous two-layer structure. Crosstalk reduction was implemented by applying a bias voltage to the n-well pixel separation, and extinction ratio was further improved. By using an improved sensor, it demonstrated a 7.6 dB SNR improvement in 30 GHz electric field imaging compared to previous sensors, despite 30% transmittance reduction. Angular dependence analysis confirmed adequate performance within the optical system’s constraints. These results enable high-speed and high-sensitivity millimeter-wave imaging applications. Full article

This research successfully synthesized a novel n-n heterojunction Bi₂O₂CO₃/AgVO₃ nanocomposite photocatalyst via the in situ chemical deposition process. Characterization results strongly confirmed the formation of a tight heterojunction at the Bi₂O₂CO₃/AgVO₃ interface. The nanocomposite exhibited characteristic XRD peaks and FT-IR vibrational modes of both Bi₂O₂CO₃ and AgVO₃ simultaneously. Electron microscopy images revealed AgVO₃ nanorods tightly and uniformly loaded onto the surface of Bi₂O₂CO₃ nanosheets. Compared to the single-component Bi₂O₂CO₃, the composite photocatalyst exhibited a red shift in its optical absorption edge to the visible region (515 nm) and a decrease in bandgap energy to 2.382 eV. Photoluminescence (PL) spectra demonstrated the lowest fluorescence intensity for the nanocomposite, indicating that the recombination of photogenerated electron–hole pairs was suppressed. After 90 min of visible-light irradiation, the degradation efficiency of Bi₂O₂CO₃/AgVO₃ toward methylene blue (MB) reached up to 99.55%, with photodegradation rates 2.51 and 2.79 times higher than those of Bi₂O₂CO₃ and AgVO₃, respectively. Furthermore, the nanocomposite exhibited excellent cycling stability and reusability. MB degradation was gradually enhanced with increasing the photocatalyst dosage and decreasing initial MB concentration. Radical trapping experiments and absorption spectroscopy of the MB solution revealed that reactive species h⁺ and ·O₂⁻ could destroy and decompose the chromophore groups of MB molecules effectively. The possible mechanism for enhancing photocatalytic performance was suggested, elucidating the crucial roles of charge carrier transfer and active species generation. Full article