Search Results (1,070)

Eye diseases are common in veterinary clinical practice and are most often treated with topical ophthalmic preparations. Increasing resistance to antimicrobial agents is driving the search for safe and effective alternatives to traditional treatment methods. The aim of this study was to develop and evaluate gel-based ophthalmic formulations based on poloxamer 407 and sodium carboxymethylcellulose, containing propolis extracts and diclofenac sodium, by assessing their physical and chemical properties, antimicrobial activity, and cytotoxicity in vitro. Propolis extracts were prepared using a solvent consisting of ethanol and choline chloride, and the developed formulations were evaluated for pH, viscosity, refractive index, gelation temperature, SIRC cell viability and apoptosis, and antimicrobial activity against clinical and reference bacterial strains. The developed formulations exhibited physicochemical properties suitable for ophthalmic preparations and antimicrobial activity, particularly against Gram-positive bacteria. Most of the concentrations of the active ingredients tested were well tolerated by SIRC cells, although higher concentrations of the ethanol propolis extract caused a greater cytotoxic effect. The results obtained indicate that gelled ophthalmic formulations based on propolis extracts and diclofenac sodium are promising for the further development of topically acting ophthalmic preparations; however, their biological efficacy and safety must be confirmed. The results obtained indicate that gelled ophthalmic formulations based on propolis extracts and diclofenac sodium are promising for the further development of topical ophthalmic preparations; however, their bioavailability and safety must be confirmed by further in vivo studies. Full article

Background/Objectives: Schlemm canal-based minimally invasive glaucoma surgery (MIGS) can be combined with cataract surgery, but topical glaucoma therapy alone is not a sufficient indication for adding MIGS. This review addresses when cataract surgery alone may be sufficient, when combined cataract surgery and MIGS may be appropriate, and when filtration surgery should be considered. Methods: This narrative review used a targeted PubMed/MEDLINE search of English-language literature published from January 2000 to May 2026 to support source identification and reference selection. The review focused on cataract surgery combined with Schlemm canal- or trabecular meshwork-targeted MIGS, including stent-based Schlemm canal procedures and trabeculotomy/goniotomy-based procedures, medication burden, ocular surface disease, refractive and visual outcomes, corneal endothelial safety, complications, angle visibility, guideline-based decision-making, and patient selection. Final references were selected according to clinical relevance to cataract-surgeon decision-making and evidence priority, with emphasis on guidelines, systematic reviews or meta-analyses, randomized or prospective comparative studies, pivotal or long-term studies, large real-world or post-market studies, and clinically informative safety, refractive, endothelial, imaging, or complication-related studies. Results: Stent-based Schlemm canal procedures and trabeculotomy/goniotomy-based procedures can provide additional IOP and medication reduction compared with cataract surgery alone in selected eyes with mild-to-moderate open-angle glaucoma. Stent-based procedures generally have a lower hyphema risk, whereas trabeculotomy/goniotomy-based procedures may provide comparable or greater IOP reduction in selected eyes but are associated with more frequent hyphema. In normal-tension glaucoma or low-baseline-IOP eyes, the expected benefit is often medication reduction or modest IOP lowering rather than reliable achievement of very low target IOP. Available refractive evidence remains limited and procedure-specific, but suggests that major refractive instability is uncommon in appropriately selected eyes. Conclusions: The decision to combine Schlemm canal-based MIGS with cataract surgery should be goal-directed rather than based solely on the presence of topical therapy. Practical selection should integrate glaucoma subtype, disease stage, baseline and target IOP, expected phacoemulsification-only IOP reduction, medication burden, ocular surface status, adherence, angle visibility, endothelial reserve, refractive objectives, and future filtration surgery options. Full article

The fading of painted relics is a widespread deterioration phenomenon in ancient painted cultural relics, yet its underlying mechanism has long been attributed solely to pigment oxidation. Directed at colored drawings with complex surface microstructures, such as pottery paintings, wall murals and architectural paintings, here we challenge this view by demonstrating that light scattering induced by sub-micron pores within the paint layer plays a dominant role, especially Mie scattering when pore sizes approach visible light wavelengths (400–700 nm). In order to minimize the damage to the genuine painted relics, a large number of simulated experiments were conducted first. Using porous polyacrylamide (PAM) membranes and nylon 6 filter membranes as model systems, we show that pore-induced scattering reduces the optical path length for light absorption, leading to a significant decrease in color saturation and brightness. By filling the pores with non-volatile colorless ionic liquids ([BMIM]PF₆) (n = 1.41) or glycerol (n = 1.47)—both possessing refractive indices close to those of the pigments—the scattering is effectively suppressed, and the original color is restored. The filling treatment reduces the color difference (ΔE*ab) by 30%–50% and the surface reflectivity by 20%–40%. Mercury intrusion porosimetry and fluorescence spectroscopy confirm that pore elimination and optical path lengthening are responsible for the color recovery. The proposed mechanism and restoration strategy were successfully validated on authentic painted brick fragments from the Western Qing Tombs (Hebei, China), where severely faded green and red patterns reappeared after ionic liquid treatment. This study provides a new interface-regulation paradigm for the conservation of painted cultural heritage, shifting the focus from irreversible chemical remediation to reversible physical restoration and offers a generalizable platform for controlling light scattering in porous optical materials. Full article

We propose a three-dimensional (3D) integrated optical switch that leverages liquid crystal (LC) birefringence to achieve reconfigurable light routing for particular suitability for quantum optical communication. In our design, the large refractive index contrast between an LC’s ordinary (n_o) and extraordinary (n_e) indices is exploited by using n_o as an effective cladding and n_e as the core of voltage-controlled waveguides. This allows dynamic waveguide formation not only in-plane (horizontal routing on chip) but also vertically through stacked polymer layers, realizing a 3D switching architecture beyond traditional planar photonic circuits. A prototype multi-layer structure on a silicon substrate is described, incorporating alternating polymer cladding and core films with embedded LC cells that act as switchable waveguide segments. Simulations confirm that the LC switch can confine and direct light between different layers with low loss, enabling compact 3 × 3 and potentially up to 10 × 10 port-count switching matrices. The device is electrically driven (no moving parts) and can be operated at low voltages, ensuring compatibility with photonic integrated circuit fabrication. The simulated LC response time on ON/OFF is on the order of 1.1 ms/45 ms, which is slower than MEMS or electro-optic switches, but, however, sufficient for quantum key distribution and other quantum network applications where ultrafast switching is not required. Overall, this LC cell-based 3D optical switch offers a promising route toward scalable, low-loss photonic switching nodes for next-generation quantum communication networks. Full article

This study investigates the feasibility of using an etched addressed fiber Bragg structure (EAFBS) as the sensing element in a microwave-photonic system for local pH monitoring. A theoretical model is developed that incorporates transmission-spectrum analysis of the addressed Bragg structure and evaluation of the effective refractive index of the guided mode as a function of the surrounding medium parameters. The model establishes a relationship between the refractive index of the surrounding medium and the spectral response of the EAFBS. Using the proposed mathematical model, numerical simulations are performed for three pH ranges corresponding to various liquid media. The results of numerical studies show that in all in the pH ranges, the address frequency varies nearly linearly, with a sensitivity of approximately 1.66 GHz/pH (pH range of 4–7), 2.64 GHz/pH (pH range of 7–10), and 1.92 GHz/pH (pH range of 10–13), whereas its temperature dependence in the range of 35–45 °C is approximately 1.06 GHz/°C. These results indicate that the proposed EAFBS-based approach can provide a foundation for high-speed pH sensing systems with a simplified interrogation scheme and potential capability for frequency-division multiplexing. Full article

2,4-Dichlorophenoxyacetic acid (2,4-D) is an extensively applied organic compound, primarily for agricultural weed control and plant growth agents. Although 2,4-D usually exists in the environment in low volumes, the detection of 2,4-D is critical for human health and environmental safety. In this work, a biophotonic biosensor was fabricated by coating the surface of a tapered optical fiber with gold nanoparticles (AuNPs) to excite the localized surface plasmon resonance (LSPR) and functionalizing the fiber with molybdenum disulfide nanosheets (MoS₂-NSs)/zinc oxide nanowires (ZnO-NWs) to extend the effective sensing area. Due to the inhibitory effect of 2,4-D on the hydrolytic activity of ALP, the refractive index (RI) around the sensor surface changes, leading to a shift in the LSPR peak wavelength. According to this sensing technique, the sensor can detect concentrations in the range of 1–10 mg/L, with a limit of detection (LOD) of 0.29 mg/L. The stability, repeatability and selectivity tests show that the sensor has good stability and selectivity. In the actual sample detection experiment, the recovery rates of apples and Chinese cabbage were 96.2–100.4% and 83.8–108.8%, respectively, which indicated that the detection method had good accuracy for the detection of target substances in actual samples. Thus, the proposed sensor has an important application in the detection of 2,4-D herbicides. Full article

This study develops a fractional Jeffreys heat conduction model to describe laser-induced thermoelastic distortions in thin optical materials under ultrafast surface heating. The framework employs three fractional parameters to characterize anomalous thermal transport modes: retarded conduction, accelerated conduction, and transitions between super- and sub-diffusive regimes. Thermo-optic effects are represented through a linear relation between temperature and refractive-index perturbation; however, a full optical-aberration decomposition is not claimed in this work. Numerical results demonstrate that anomalous heat transfer significantly affects temperature localization, heat-flux evolution, stress distributions, and OPD-based thermo-optic indicators in components subjected to ultrafast laser pulses. Quantitative optical indicators, including refractive-index variation, optical path difference, wavefront error, focal-length shift, and thermal-lens distortion, are derived from the computed temperature field to connect the thermal solution directly with thin-lens performance. Simulations combining Maple2024 and MATLAB R2023a quantify the coupled thermoelastic-optical response at picosecond time scales. Full article

Diabetes mellitus represents a major global health burden, necessitating the development of safer and more effective therapeutic alternatives. Medicinal plants have gained increasing attention due to their bioactive compounds with potential hypoglycemic and antioxidant effects. The present study aimed to investigate the physicochemical characteristics, phytochemical composition, antioxidant capacity, and toxicological profile of hydroalcoholic tinctures obtained from Agrimonia pilosa Ledeb., Calendula arvensis L., and Polygonum hydropiper L. The tinctures were prepared by simple percolation using 70% ethanol and evaluated according to pharmacopoeial standards, including organoleptic properties, relative density, refractive index, alcohol content, and purity parameters. Phytochemical analysis was performed using thin-layer chromatography and spectrophotometric methods, highlighting the presence of flavonoids and polyphenolcarboxylic acids, with several bands showing chromatographic and spectral similarities to chlorogenic and caffeic acid standards. Antioxidant activity was assessed through total polyphenol and flavonoid content, with Polygonum hydropiper exhibiting the highest values. The hypoglycemic effect was evaluated using the oral glucose tolerance test in normoglycemic mice, demonstrating significant reductions in blood glucose levels, particularly for Agrimonia pilosa at higher doses. Acute toxicity studies indicated a low toxicity profile, with no mortality observed even at high doses (up to 9 g/kg body weight), corresponding to GHS category 5. However, subacute toxicity assessment revealed species-dependent effects, ranging from minimal hepatic changes for Calendula arvensis to moderate hepatotoxicity for Polygonum hydropiper and more pronounced hepatic, renal, and pancreatic alterations for Agrimonia pilosa. These findings suggest that the investigated tinctures possess significant hypoglycemic and antioxidant potential, with generally favorable safety profiles following acute administration. Nevertheless, prolonged use may induce organ-specific toxicity, highlighting the need for further pharmacological and clinical investigations to establish their therapeutic applicability and safety in diabetes management. Full article

Ultra-High-Frequency (UHF) or Ultra-High-Resolution (UHR) seismic data can image in detail several meters below the seafloor, especially in shallow waters, where the assessment of the subsurface is critical for future nearshore construction. The method can detect the subsurface structure in detail in UHF seismic records, which are characterized by a high amount of diffracted energy. With the aim of enhancing the lateral continuity and resolution for the reflectors, we applied a multipath summation approach for the first time at such high frequencies. We employed strategies for separating the diffractions from the total signal in order to clearly take advantage of their AI-located apices for further velocity analysis. The derived Root Mean Square (RMS) velocity models did not prove to be sufficient for direct migration, something that the multipath summation using 2D stacking weights sufficiently solved. We combined the focused-energy seismic sections with the derived interval-velocity models and took into consideration the available borehole data to interpret the subsurface structure. We observed a sufficient enhancement of the P-wave refraction velocity models commonly derived in such investigations. This enhancement involved not only the resolution but also the additional indications of velocity reversals, which can be a severe drawback for the stability of offshore infrastructure due to the possibility of their hazardous origin, such as fractures, unstable bedrock, or voids. Full article

Monocrystalline silicon, with its high refractive index, high infrared transmittance, and excellent dimensional stability, serves as a key optical component in high-energy laser systems, infrared imaging, and guidance fields. Its processing quality directly affects the performance indicators of related systems. To address the challenges of nanoscale precision shape and property control during processing, methods such as ultra-precision cutting, magnetorheological polishing, laser micromachining, ion beam processing, plasma etching, and chemical–mechanical polishing have been adopted to improve the surface shape accuracy and repair defects of monocrystalline silicon components. This paper reviews the research progress of key technologies, including nanoscale precision surface shape control manufacturing technology, nanoscale precision property control generation methods, and combined processes for its nanoscale shape and property control, providing technical support for achieving nanoscale precision shape and property control manufacturing of monocrystalline silicon components. Full article

Background/Objectives: To evaluate subclinical structural and functional retinal alterations in clinically normal myopic eyes using optical coherence tomography (OCT) and automated visual field analysis. Methods: This retrospective observational study included 109 patients aged 18–42 years categorized according to spherical refractive component, while spherical equivalent (SE) was calculated to quantify refractive severity. Only the right eye of each participant was analyzed. Patients were categorized into five refractive groups according to spherical refractive component. All participants underwent comprehensive ophthalmologic examination, axial length (AL) measurement, spectral-domain OCT imaging, and standard automated perimetry. Structural parameters included central retinal thickness (CRT) and OCT-derived nerve fiber layer central thickness (OCT-NFCT). Functional assessment included visual field central zone sensitivity (VF-CZ), peripheral zone defect value (VF-PZ), mean deviation/defect value (VF-MD), and square root of loss variance (VF-sLV). Correlation and regression analyses were performed to evaluate relationships among absolute myopia severity, AL, OCT parameters, and visual field indices. Results: Increasing myopia was associated with significant reductions in CRT (p < 0.001) and significant intergroup differences in OCT-NFCT (p = 0.012). A moderate negative correlation was observed between absolute spherical equivalent/myopia severity and CRT (r = −0.5398, p < 0.001), whereas the association with OCT-NFCT was not statistically significant (p = 0.149). Visual field parameters demonstrated significant deterioration with increasing myopia (all p < 0.001). VF-CZ showed a strong negative correlation with myopia severity (r = −0.8545, p < 0.001), whereas VF-PZ (r = 0.8196, p < 0.001), VF-MD (r = 0.8186, p < 0.001), and VF-sLV (r = 0.7606, p < 0.001) demonstrated strong positive correlations. In multivariable regression analysis, BCVA, AL, and absolute SE were independently associated with VF-CZ, whereas age and absolute SE were independently associated with VF-MD. CRT and OCT-NFCT were not independent predictors of visual field outcomes. Conclusions: Clinically normal myopic eyes demonstrate significant subclinical structural and functional retinal alterations. In this cross-sectional dataset, visual field alterations were detectable across refractive categories and appeared to be more strongly associated with axial elongation and myopia severity than isolated retinal thickness alterations. Combined OCT and visual field assessment may be valuable for early detection and monitoring of subclinical retinal involvement in myopic patients. Full article

Traditional tunable Bragg waveguide grating filters, which rely on thermo-optic or carrier effects, often face limitations such as high energy consumption, low tuning efficiency, and difficulty in achieving independent multi-parameter control. To overcome these bottlenecks, this work proposes a novel optical waveguide filter based on the heterogeneous integration of silicon nitride and the phase-change material Sb₂Se₃. The device leverages the substantial refractive index contrast between crystalline and amorphous states of Sb₂Se₃ to construct a programmable Bragg grating within the thin film layer. This is realized through laser-induced phase transition method, enabling nonvolatile manipulation of the light field. Simulation results indicate that the independent tuning of central wavelength over 19.2 nm range was achieved by adjusting the grating width and ripple width simultaneously. Likewise, the extinction ratio could be independently controlled over 22.3 dB through coordinated adjustments of the grating length and position shift. Beyond its tuning capabilities, the proposed device theoretically exhibits exceptional performance characteristics, including an ultra-low insertion loss of 0.1 dB and strong side lobe suppression. These advantages highlight the potential of this approach to provide a low energy consumption, multifunctional solution for integrated photonic devices, offering a promising pathway for the next generation of programmable photonic integrated circuits. Full article

Background: Uncorrected visual impairment, primarily due to refractive errors, is a persistent public health concern in low- and middle-income countries. In Malawi, national data on the prevalence of visual difficulty and uptake of optical correction remain scarce, hindering targeted health interventions. This study examines the prevalence of self-reported visual difficulties, the uptake of refractive correction, and the sociodemographic determinants of optical correction in Malawi using 2024 national survey data. Methods: We conducted a secondary analysis of data from the 2024 Malawi Demographic and Health Survey (MDHS), a nationally representative, cross-sectional survey encompassing 23,095 participants across urban and rural regions. Self-reported visual difficulties and optical correction (spectacle/contact lens use) were assessed alongside key sociodemographic factors. Associations were examined using chi-square tests and multinomial logistic regression. Results: Among 23,095 participants, visual difficulty was significantly associated with age, education, marital status, region, and residence (all p < 0.001). The prevalence of visual difficulty increased markedly with age, from 2.3% in the youngest group to 15.5% in those over 74 years. Women, individuals with lower education, widowed participants, and residents of the Northern region experienced higher rates of visual difficulty. Spectacle or contact lens use was low overall (6.4%), with uptake increasing with age, education, and urban residence but remaining below 20% even among the most educated. Most individuals reporting visual difficulty were not using optical correction, including 70% of those with “some difficulty” and 67% of those with “a lot of difficulty” indicating substantial unmet need. Multivariable analysis identified advancing age, higher education, urban residence, and Northern region as key independent predictors of both visual difficulty and refractive correction uptake. Conclusions: The unmet need for refractive correction in Malawi is substantial, disproportionately affecting older, less educated, rural, and widowed individuals. Expanding access to affordable and equitable refractive services is essential to reducing avoidable visual impairment and addressing social and geographic health disparities. Full article

This study presents a systematic terahertz time-domain spectroscopy (THz-TDS) investigation of hardened cement paste, framed as a complex-optical measurement in which the real and imaginary parts of the response probe distinct microstructural attributes. Transmission-mode measurements were made on pastes with water-to-cement (w/c) ratios of 0.3, 0.4, and 0.5 at curing ages of 7, 14, 28, and 56 days. The effective refractive index, obtained from the time-domain pulse delay (7, 28, and 56 days, paired with mercury intrusion porosimetry), correlates strongly and linearly with porosity over nine porosity-paired conditions spanning 15.1–30.4% (pooled R² = 0.94, p < 0.001). In a quasi-static effective-medium framework—where the pores a re far smaller than the THz wavelength—this reflects the dependence of the effective permittivity on the solid volume fraction: the Bruggeman model outperforms the Maxwell–Garnett model, and all data fall within the Wiener bounds, lying close to the upper bound, indicating a continuously connected solid matrix with isolated pores. Cross-validated porosity estimation is reliable to within about ±2 percentage points (refractive-index uncertainty ±0.02–0.04). The absorption follows a power law (β ≈ 1.0–1.3) characteristic of disorder-activated vibrational absorption, in which the loss of long-range order in the amorphous C–S–H relaxes the crystalline selection rules and couples the THz field to the full vibrational density of states. The refractive index (structure-sensitive, governed by volume fraction) and the absorption (material-sensitive, governed by solid disorder; estimated loss tangent of order 0.1) thus form two complementary channels. Combining the THz-derived porosity with the Powers hydration model gives a degree of hydration consistent with literature ranges—an indirect comparison rather than direct validation. These results establish THz-TDS as a non-contact, non-ionizing technique for rapid porosity estimation and hydration assessment of cementitious materials. Full article

Background: Age-related macular degeneration (AMD) is the leading cause of irreversible vision loss in older adults. An important challenge is the recognition of its early asymptomatic stages and the monitoring of its progression, which requires reliable biomarkers. Growing evidence indicates that AMD-related biochemical changes are reflected in the proteome of tear fluid (TF). Although TF is a non-invasive and easily collectable diagnostic material, its proteomic analysis is complex and costly and therefore has limited clinical value. Methods: In this pilot single-center retrospective cross-sectional study, we developed a new method for dry AMD screening based on analysis of nano-differential scanning fluorimetry (nanoDSF) tear protein denaturation profiles (TDPs) within 15 min. The TDPs were recorded in representative groups of dry AMD patients (37% early, 48% intermediate, 15% geographic atrophy), and in control groups, including patients with refractive abnormalities (basic control), other retinal degenerative diseases (diabetic retinopathy, peripheral retinal dystrophy), or TF-affecting conditions (dry eye syndrome). High-dimensional TDP data were processed using unsupervised machine learning followed by k-means cluster analysis. Results: The presented pipeline distinguished AMD from the basic control with 74% accuracy and a sensitivity of 0.81 without relying on prior labels. The specificity of AMD detection was confirmed by its effective differentiation from diabetic retinopathy (72%; 0.74), peripheral retinal dystrophy (79%; 0.76) and dry eye disease (76%; 0.81). Classifying the AMD group from the entire population of other patients yielded an accuracy of 71% and a sensitivity of 85%, with a false-negative rate of only 15%. Conclusions: This study is a proof of concept for the nanoDSF-based approach, which can be considered a fast, cost-effective, and convenient tool for population screening for dry AMD, suitable for use in preventive medicine and public health. Full article