Search Results (795)

Fiber-optic gyroscopes (FOGs) have become one of the most important elements of modern inertial navigation systems due to their high accuracy, reliability, and independence from external signals such as satellite navigation. This review analyzes and discusses the key FOG architectures: interferometric (IFOG), resonant (RFOG), digital (DFOG), and hybrid (HFOG). The concepts of their functioning, structural features, and the main advantages and limitations of each architecture are examined. Particular focus is placed on advanced signal-processing and error-compensation algorithms, including filtering techniques, noise suppression, mitigation of thermal and mechanical drifts, and emerging machine learning (ML) based approaches. The analysis of these architectures is carried out in terms of major parameters that determine accuracy, robustness, and miniaturization potential. Various applications of FOGs in space systems, ground platforms, marine and underwater navigation, aviation, and scientific research are also being considered. Finally, the latest development trends are summarized, with a particular focus on miniaturization, integration with additional sensors, and the introduction of digital and AI-driven solutions, aimed at achieving higher accuracy, long-term stability, and resilience to real-world disturbances. Full article

Contaminated water detoxification remains difficult due to the presence of persistent halo-organic contaminants, such as perfluorooctanoic acid (PFOA) and chlorophenols, which are chemically stable and resist conventional purification methods. Functionalized membrane-based separation and decontamination have garnered immense attention in recent years. Commercially available microfiltration membrane (PVDF) and polymeric non-woven fiber filters (glass and composite) are functionalized with poly(methacrylic acid) (PMAA) that shows outstanding pH-responsive performance and tunable water permeability under ambient conditions perfect for environmental applications. Polymer loading based on weight gain measurements on PMAA–microglass composite fibers (137%) and microglass fibers (116%) confirmed their extent of functionalization, which was significantly greater than that of PVDF (25%) due to its widely effective pore diameter. Presence of chemically active hydrogel within PVDF matrix was validated by FTIR (hydroxyl/carbonyl) stretch peak, substantial decrease in contact angle (68.8° ± 0.5° to 30.8° ± 1.9°), and decrease in pure water flux from 509 to 148 LMH/bar. Nanoparticles are generated both in solution and within PVDF using simple redox reactions. This strategy is extended to PVDF-PMAA membranes, which are loaded with Fe/Pd nanoparticles for catalytic conversion of 4-chlorophenol and PFOA, forming Fe/Pd-PVDF-PMAA systems. A total of 0.25 mg/L Fe/Pd nanoparticles synthesized in solution displayed alloy-type structures and demonstrated a strong catalytic performance, achieving complete hydrogenation of 4-chlorophenol to phenol and 67% hydrogenation of PFOA to its reduced form at 22–23 °C with ultrapure hydrogen gas supply at pH 5.7. These results underscore the potential of hybrid polymer–nanoparticle systems as a novel remediation strategy, integrating tunable separation with catalytic degradation to overcome the limitations of conventional water treatment methods. Full article

The use of focal plane array micro-Fourier transform infrared spectroscopy (FPA-μFTIR) enables high-resolution characterization of microplastics (MPs) in a wide variety of matrices, including both biotic and abiotic samples. However, this technique has not yet been applied to study MP ingestion in organisms in areas with low MP pollution (e.g., national parks or protected areas). In this study, FPA-μFTIR was used to quantify MPs in the bodies of aquatic insects collected from a high-altitude stream (~2000 m) in Taiwan. Results showed that MP ingestion occurred in nearly all examined taxa, except for caddisfly (Trichoptera: Stenopsychidae) and dragonfly (Odonata: Gomphidae). The majority of MPs were smaller than 500 μm, and the dominant MP polymers identified were polyethylene (65%) and polypropylene (30%), which occurred mainly as fragments (83%) and, to a lesser extent, as fibers (17%). The highest number of MP particles was in the scraper functional-feeding group (FFG), while MPs were not detectable in collector–filterer FFG. The highest MP concentration (particles/individuals) was found in the waterpenny beetle Ectopria sp., followed by the mayflies Paraleptophlebia sp. and Epeorus erratus, and Chironomidae in the subfamily Tanypodinae. We suggest that using high-resolution FPA-μFTIR can be effectively applied to study and monitor MP ingestion in remote, pristine ecosystems. Full article

Urban stormwater runoff, particularly during first-flush events, carries high loads of fine suspended solids and phosphorus that are difficult to remove with conventional best management practices (BMPs). This study developed and evaluated a laboratory-scale high-efficiency up-flow filtration system with Internet of Things (IoT)-based autonomous control. The system employed 20 mm fiber-ball media in a modular dual-stage up-flow configuration with optimized coagulant dosing to target fine particles (<3 μm) and total phosphorus (TP). Real-time turbidity and pressure monitoring via sensor networks connected to a microcontroller enabled wireless data logging and automated backwash initiation when thresholds were exceeded. Under manual operation, the two-stage filter achieved removals of 96.6% turbidity, 98.8% suspended solids (SS), and 85.6% TP while maintaining head loss below 10 cm. In IoT-controlled single-stage runs with highly polluted influent (turbidity ~400 NTU, SS > 1000 mg/L, TP ~1.6 mg/L), the system maintained >90% SS and ~58% TP removal with stable head loss (~8 cm) and no manual intervention. Turbidity correlated strongly with SS (R² ≈ 0.94) and TP (R² ≈ 0.87), validating its use as a surrogate control parameter. Compared with conventional BMPs, the developed filter demonstrated superior solids capture, competitive phosphorus removal, and the novel capability of real-time autonomous operation, providing proof-of-concept for next-generation smart BMPs capable of meeting regulatory standards while reducing maintenance. Full article

A flexible and packed-type air filter ball (AFB) system was developed for the efficient removal of particulate matter (PM) and formaldehyde (HCHO). The Mg/Si-embedded AFB (Mg/Si-AFB) was synthesized through sequential physical etching of a sponge, oxidation of glass fiber, and subsequent formation of Mg-Si components. The resulting Mg/Si-AFB exhibited a highly porous and roughened architecture with enhanced surface reactivity. A disk-type filtration device loaded with Mg/Si-AFBs demonstrated a PM_2.5 removal efficiency (RE) of 97.4% at a pressure drop of 57 Pa. The RE increased with packing density and PM concentration and notably remained constant even at high air velocities (7 m/s). In addition, the oxidized glass fiber (GF)-based AFB (O-GF-AFB) exhibited rapid HCHO adsorption capability, achieving 100% HCHO removal within 1 min. Hybrid air filters combining Mg/Si-AFBs and O-GF-AFBs in an equal ratio (8:8) exhibited synergistic performance, simultaneously achieving 97.1% PM_2.5 RE and complete HCHO removal within 1–6 min, while maintaining low pressure drops (55–57 Pa) over 50 reuse cycles. Full article

Glaucoma is recognized as the second leading cause of blindness globally and a primary cause of irreversible blindness, estimated to affect over 80 million patients worldwide, including 4.5 million in the United States. Though the disease is multifactorial, the primary cause is elevated intraocular pressure (IOP), which damages the optic nerve fibers that connect the eye to the brain, thus interfering with the quality of vision. Current treatments have evolved, which consist of medications, laser therapies, and surgical interventions such as filtering procedures, glaucoma drainage devices (GDDs), and current innovations of minimally invasive glaucoma surgeries (MIGS). This paper aims to discuss the history and evolution of the design and biomaterials employed in GDDs and MIGS. Through a comprehensive review of the literature, we trace the development of these devices from early concepts to modern implants, highlighting advancements in materials science and surgical integration. This historical analysis, ranging from the mid-19th century, reveals a trend towards enhanced biocompatibility, improved efficiency in IOP reduction, and reduced complications. We conclude that the ongoing evolution of GDDs and MIGS underscores a persistent commitment to advancing patient care in glaucoma, paving the way for future device innovations and therapeutic trends to treat glaucoma. Full article

The growing demand for efficient hydrogen storage solutions highlights the need for reliable and safe composite overwrapped pressure vessels (COPVs). This study investigates the application of an inline monitoring system combining laser-based measurements and photogrammetric line photography to assess COPV quality during fabrication, including quantitative evaluation of liner concentricity and high-resolution line scanning of the composite surface to detect and measure fiber orientations. Fiber detection and angle measurement using the Hough Transform provide detailed assessment of local winding orientation, while global Fourier Transform analysis supports comparative evaluation across vessels or segments, allowing identification of dominant fiber directions and detection of micro-scale deviations. The integrated approach enables early detection of geometric inconsistencies and localized winding irregularities, providing robust performance-based criteria for accept-reject decisions, while filtering out minor noise and ensuring reliable quantitative evaluation. This framework enhances inline quality control, optimizes material usage, and supports the safe deployment of COPVs in hydrogen storage systems, contributing to efficient and reliable energy storage solutions. Full article

Demand for clothing is estimated to increase globally by 4.5% per year, and secondhand clothing is often used to fill that demand. A clear understanding of the environmental impact of secondhand items would support transparency around sustainability, which is a rising consumer concern. This study focuses on the characteristics of the fiber fragment material released during the laundering of secondhand, 100% cotton denim clothing, and the implications of secondhand clothing’s contribution of fiber fragments to the environment. The test method used was AATCC TM212-2021, with detergent, conditioned specimens, and filters. The specimens included thirteen pairs of secondhand men’s 100% cotton jeans (SHS) and two pairs of new jeans (CN controls). This study concluded that the amount of fiber fragmentation material shed by SHS was 23.2% of that shed by CN. While this is less than is shed by new clothing, there is still shed material to consider, including dyes and processing chemicals that can contribute to anthropogenic contamination of the environment. The fiber fragment size and frequency were found to have statistically significant differences between SHS (length 370.5 µm, diameter 16.9 µm, 3093 fiber fragments per filter) and CN (320.7 µm, 13.8 µm, and 5962 fiber fragments per filter). Full article

Varied types of particulate matter (PM) persist in the environment and exert a harmful impact on public health. The aim of this review article is to explore the key role of membrane technology in the separation of PM from ambient air. Nanofibrous, microporous, Janus, photocatalytic and hollow fiber membranes have found significant utilization in the effective separation of PM. Recent advancements in membrane technology and their key properties such as antibacterial activity, flame retardancy, wettability, thermal stability and reusability have been underscored in this review article. Moreover, the principles of PM separation have been discussed in detail to understand the working pathway of a membrane air filter via physical, chemical or biological approaches. A brief comparison between the conventional air filters and membrane air filters is provided in terms of cost, separation principle and respective merits and demerits to understand the importance of membranes in the realm of PM separation. This study also highlighted the commercial status of PM air filters with respect to their cost and scalability. By focusing on the innovations in membrane filters, this review article has highlighted the futuristic approaches such as green fabrication techniques, highly efficient material incorporation, use of AI/ML, etc., to overcome the challenges associated with conventional air filters. Full article

This paper presents a fiber-optic sensor with intensity demodulation for simultaneous measurement of dynamic transverse force and axial strain. The sensor uses a Sagnac loop filter with a polarization-maintaining photonic crystal fiber (PM-PCF) that is subjected to a dynamic transverse force. The Sagnac loop filter is illuminated by the reflected beam froma uniform fiber-optic Bragg grating (FBG), which is subjected to an axial strain. This way, intensity demodulation is performed in the sensor, enabling it to measure two quantities simultaneously: the dynamic force and the strain. Experimental results show that the sensor achieves a sensitivity to the dynamic transverse force of 38.1 mV/N and a sensitivity to the axial strain of 0.527 mV/με, while the nonlinearity errorsare 4.9% for the dynamic force and 0.9% for the strain. The sensor exhibits low temperature sensitivity due to partial self-compensation of the temperature coefficients of the Sagnac loop filter with the polarization-maintaining photonic crystal fiber and the fiber Bragg grating. Full article

To explore the potential of new information transmission windows, this work presents a broadband plasmonic filter based on gold-deposited silicon photonic crystal fiber (PCF) operating in mid-infrared regime numerically, using the finite element method (FEM). The simulation results indicate that the interaction between the high-refractive-index pure silicon material and the gold layer can cause a shift of the resonance central point to the mid-infrared band, which provides the prerequisite for mid-infrared filtering. When the cladding holes’ diameter is 1.3 µm, the inner holes’ diameter is 1.04 µm, the diameter of the holes located on both sides of the core region is 2.08 µm, the gold-coated holes’ diameter is 2.08 µm, the lattice constant is 2 µm, and the gold thickness is 50 nm, this PCF can operate in the mid-infrared band near the central wavelength of 3 µm. The 1 mm long PCF polarizer exhibits a maximum extinction ratio (ER) of −43.5 dB at 3 µm and a broad operating bandwidth of greater than 820 nm with ER better than −20 dB. Additionally, it also possesses high fabrication feasibility. This in-fiber polarization filter, characterized by its comprehensive performance and ease of fabrication, aids in exploring the development potential of high-speed and large-capacity modern communication networks within new optical bands and contributes to new photonic computing and sensing. Full article

We begin by theoretically analyzing the relationship between the rotation rates of the rotation of state of polarization (RSOP) and the principal state of polarization (PSP) in a fiber link where both polarization mode dispersion (PMD) and time-varying RSOP are present. The theoretical analysis is validated through numerical simulations. Our findings reveal that the rotation rates of both the input and output PSPs significantly differ from the channel’s RSOP rate in most scenarios. Moreover, under varying RSOP distribution scenarios within the channel, the relationships among the rotation rates of input PSP, output PSP and RSOP also differ, and therefore rotation rates of input or output PSPs can reflect the changes of RSOP, indicating that monitoring PSP rotation rate can enable a better understanding of RSOP. Furthermore, we propose a DSP-based algorithm for monitoring PSPs and their rotation rates. By jointly applying a sliding-window median filter and a modulus judgment procedure, the algorithm yields more accurate PSP trajectories and rotation rate estimates than the existing approaches in literature, while relying solely on the existing DSP module without requiring any additional hardware. The recovered PSP orientation and rotation rate information can then be fed into the CMA equalizer, enhancing its compensation performance and thereby improving the overall stability and performance of the coherent optical system. Full article

This study investigated the effects of Rhodopseudomonas palustris (R. palustris) supplementation on the rumen microbiota of Leizhou goats and explored its potential mechanisms. Thirty healthy Leizhou goats of similar weight and age were selected and randomly assigned to five groups (six goats per group) using a completely randomized block design for a 75-day feeding trial. The control group (CONRF) was fed a basal diet, and the Photosynthetic Bacteria Medium (PBMRF) group was fed a basal diet + PBM solution. The low-concentration R. palustris (LRPRF), medium-concentration R. palustris (MRPRF), and high-concentration R. palustris (HRPRF) groups were fed a base diet supplemented with 20.0 mL, 40.0 mL, and 80.0 mL of R. palustris solution, respectively. All supplements were administered by mixing them into the feed. On day 75 of the trial, three goats were randomly selected from each group for slaughter and evisceration. Rumen contents were collected, immediately filtered, aliquoted, quick-frozen in liquid nitrogen, and stored at −80 °C for subsequent analysis of rumen microbial diversity. Rumen microbial community structure was analyzed using high-throughput sequencing. The results showed that R. palustris enriched unique operational taxonomic units (OTUs), particularly in the LRPRF group. At the phylum level, Firmicutes and Bacteroidota were dominant; Firmicutes and Euryarchaeota abundance increased, while Bacteroidota decreased in the experimental groups. In addition, Verrucomicrobiota abundance was significantly elevated (p < 0.05). At the genus level, Prevotella was predominant, whereas Selenomonas abundance was significantly reduced (p < 0.01). Meanwhile, compared to the CONRF, PBMRF, and LRPRF groups, the MRPRF and HRPRF groups exhibited higher relative abundances of Christensenellaceae_R-7 group and Anaeroplasma. LEfSe analysis revealed a greater number of differential taxa in the experimental groups compared with the control, including enrichment of beneficial bacteria, such as Lactobacillus, which may contribute to optimizing the rumen environment by regulating immune and metabolic functions. Functional prediction indicated that rumen microorganisms were mainly involved in carbohydrate and amino acid metabolism. In conclusion, supplementation with R. palustris can beneficially modulate rumen microbial composition and function and promote rumen absorption of nutrients and degradation of crude fiber. This study provides a theoretical basis for green goat farming practices. Full article

Polarization-induced noise remains a primary source of bias drift, fundamentally limiting the performance of hollow-core photonic-crystal fiber optic gyroscopes (HC-RFOGs). To overcome this limitation, we propose and demonstrate a novel resonator design with an intrinsically high polarization extinction ratio (PER). The resonator’s core innovation is a four-port coupler architecture that strategically integrates a pair of polarization beam splitters (PBSs) with conventional beam splitters (BSs). This configuration functions as a high-fidelity polarization filter, suppressing undesired polarization states for both clockwise and counter-clockwise propagating light within the hollow-core fiber loop. Our theoretical model predicts that the effective in-resonator PER can exceed 48 dB, which is sufficient to mitigate polarization-related errors for tactical-grade applications. Experimental validation of a prototype HC-RFOG incorporating this resonator yields a bias instability of 1.34°/h and an angle random walk (ARW) of $0.078°/\sqrt{\mathrm{h}}$ (with a 200 s averaging time). These results confirm that engineering a high-polarization-extinction-ratio resonator (HPERR) is a potent and direct pathway to substantially reducing polarization noise and advancing the performance of HC-RFOGs. Full article

Electrospun fibrous scaffolds based on cellulose acetate (CA), polycaprolactone (PCL), and poly (L-lactic acid) (PLLA) are versatile materials with applications spanning diverse fields, but in their pristine form, they typically lack significant inherent antibacterial properties. To address this limitation and expand their utility, this study explored the incorporation of xylitol, a natural antibacterial sugar alcohol, into these polymer matrices to enhance their physicochemical and antimicrobial properties. Electrospinning was employed to fabricate pristine and xylitol-loaded scaffolds with varying xylitol concentrations. Morphological analysis revealed polymer-dependent changes in fiber diameter and porosity. Mechanical testing assessed the impact of xylitol on tensile properties, while thermal analysis investigated alterations in melting temperature and crystallinity. The antibacterial efficacy against Staphylococcus aureus and Escherichia coli was evaluated using WST assay and live/dead staining. Notably, xylitol significantly enhanced the antibacterial activity against both bacterial species, with a more pronounced and rapid effect observed against S. aureus. The tailored scaffold properties and imparted antimicrobial characteristics highlight the potential of these xylitol-modified electrospun materials: they are easily produced, low-cost, and appropriate for a range of applications (dental applications, filters, masks, wound dressing, and packaging) where preventing bacterial contamination is crucial. Full article