Search Results (4,956)

In this study, for the first time, ZnO nanoparticles doped with noble metals (Pt, Ag, Au) were employed as a solid contact in nitrate ion-selective electrodes based on a glassy carbon internal electrode, and their performance was described and studied. Nanoparticles were synthesized by pulsed laser ablation in liquid. They were placed as an intermediate layer between the inner electrode and the ion-selective membrane. The impact of nanoparticle type on electrode performance was assessed by analyzing their analytical and electrical parameters using both potentiometry and electrochemical impedance spectroscopy. It was found that the determined properties of hybrid nanoparticles, as well as their effectiveness as a solid contact, depend significantly on the type of metal doping. Doping ZnO nanoparticles with metals increases their electrical capacity and reduces contact angles. The best results were obtained for the electrode modified with platinum-doped zinc oxide nanoparticles, characterized by the largest electric capacitance and the most hydrophobic properties among the hybrid nanoparticles. This electrode has been successfully used for the potentiometric determination of nitrate content in soil. Full article

To investigate the dynamic instability mechanism of surrounding rock in deep, rockburst-prone coal seams, a Split Hopkinson Pressure Bar (SHPB) system was utilized to carry out dynamic impact compression tests on Rock–Coal–Rock (RCR) composites featuring four different seam dip angles, namely 0°, 15°, 30°, and 45°. We systematically analyze incorporating high-speed imaging, the mechanical properties, energy evolution, and progressive failure characteristics of the composites under various strain rates. The results indicate that the dynamic compressive strength and elastic modulus of the composites exhibit a significant strain-rate hardening effect. With the increase in the dip angle of the coal seam, the compressive strength of the specimen decreases accordingly. Specifically, the range of 15–30° is identified as a critical transition zone where the failure mode shifts from matrix-dominated bearing to interfacial slip instability. At an impact pressure of 0.12 MPa, the compressive strength drops by 36.9% within this interval. Furthermore, the energy distribution is profoundly modulated by the geometric characteristics of the interface. As the dip angle increases, the degree of wave impedance mismatch at the coal–rock interface intensifies, leading to a sharp rise in the reflected energy ratio (up to 80.7%) and a pronounced attenuation of transmitted energy. Notably, the dissipation energy per unit volume increases with the dip angle, revealing that interfacial sliding and frictional work become the primary energy dissipation pathways under large-inclination conditions. High-speed camera monitoring confirms that the instability mechanism shifts from axial splitting/tension to an interfacial shear-slip mode as the dip angle increases. These findings provide a scientific reference for the stability evaluation of roadway surrounding rock and the prevention of dynamic disasters. Full article

Inspired by observations of manta ray gliding, this study designed and evaluated a more biologically accurate pectoral fin bending model. We assessed its hydrodynamic performance using six-degrees-of-freedom (6-DoF) Computational Fluid Dynamics (CFD) simulations, which were validated by tethered water tunnel experiments. Key findings reveal that symmetric bending significantly impacts longitudinal stability, increasing the pitch angle to nearly twice that of the flat-wing model (80° model) but compromising gliding efficiency. During this symmetric motion, the lift-to-drag ratio (K) minimum point is significantly delayed as the bending angle increases, following a negative quadratic trend. Conversely, asymmetric bending triggers a sharp 3.5-fold increase in the roll angle (80° vs. 30° model) and produces significant lateral displacement. Importantly, “roll-induced yaw” was confirmed as the dominant mechanism for lateral control, contributing up to 88.5% of the lateral force in the 80° model, despite minimal changes in the yaw angle. These findings reveal the intrinsic trade-offs between fin deformation, gliding efficiency, and attitude control, providing a theoretical basis for active configuration optimization and control strategies for bionic gliders. Full article

This study examines the impact of synthesized silica nanofluid on wettability and interfacial tension in sandstone reservoirs to enhance oil recovery. The parameters of the nanofluid are assessed using methods such as a DLS Zetasizer, contact angle measurements, and tensiometer. Preliminary findings indicate stable nanoparticle distribution and further results show significant wettability alterations and reduced interfacial tension, suggesting the nanofluid’s potential in optimizing fluid–rock interactions for enhanced oil recovery. This study highlights the potential of nanotechnology in the petroleum industry, provides a new understanding of fluid behavior in porous media, and increases the understanding of nanofluid-enhanced reservoir engineering. Full article

The increasing adoption of digital light processing (DLP) three-dimensional (3D) printing in prosthodontics has enabled the rapid fabrication of denture bases with improved dimensional accuracy and reproducibility. However, the mechanical performance and surface characteristics of 3D-printed denture base resins remain inferior to those of conventional heat-polymerized polymethyl methacrylate (PMMA), limiting their long-term clinical reliability. This study aimed to investigate the effect of incorporating zinc oxide (ZnO) and samarium oxide (Sm₂O₃) nanoparticles, individually and as hybrid nanofiller systems, on the mechanical and wettability properties of a DLP 3D-printed denture base resin. ZnO and Sm₂O₃ nanoparticles were incorporated into a photopolymerizable denture base resin at concentrations of 1 and 2 wt.%, producing seven experimental formulations, including a control group. A total of 280 specimens were fabricated using a DLP 3D printer and subjected to standardized post-processing. Nanoparticle dispersion and morphology were examined using field-emission scanning electron microscopy (FE-SEM), while Fourier-transform infrared spectroscopy (FTIR) was employed to assess possible chemical interactions between the nanofillers and the polymer matrix. Mechanical performance was evaluated through impact strength, transverse strength, and flexural strength tests, and surface wettability was assessed using static water contact angle measurements. Statistical analysis was conducted using one-way ANOVA followed by Tukey’s post hoc test (α = 0.05). The results demonstrated that all nanoparticle-reinforced groups exhibited significantly enhanced mechanical properties compared with the unmodified control resin. The incorporation of 1 wt.% nanofillers yielded the most pronounced improvements, with the 1 wt.% ZnO group achieving the highest transverse strength and the 1 wt.% ZnO–Sm₂O₃ hybrid group exhibiting the maximum flexural strength. Increasing the nanofiller concentration to 2 wt.% resulted in partial reductions in impact and flexural strength, which were attributed to nanoparticle agglomeration and increased light scattering during photopolymerization. FTIR analysis revealed no evidence of chemical bonding between the resin matrix and the nanofillers, indicating that the observed enhancements were primarily governed by physical reinforcement mechanisms. Wettability analysis showed that Sm₂O₃-containing formulations significantly reduced the water contact angle, indicating increased surface hydrophilicity, whereas ZnO incorporation produced more hydrophobic surfaces. Within the limitations of this in vitro study, the findings suggest that low-concentration incorporation of ZnO and Sm₂O₃ nanoparticles represents an effective strategy to enhance the mechanical integrity and tailor the surface properties of DLP 3D-printed denture base resins. These results suggest potential clinical relevance of nanoparticle-reinforced printed denture bases, emphasizing the importance of optimized filler loading to avoid agglomeration-induced performance degradation. Full article

Aiming to solve the persistent problem of edge cracking in magnesium alloy cast-rolling, this numerical simulation study introduces an innovative magnetic field-assisted approach. Utilizing Lorentz force, the process dynamically transforms the solidification front morphology from an arc-shaped (“Ɔ”) to a linear (“1”) configuration. Simulation results reveal that, while magnetic field-induced thermal effects minimally impact the solidification front, the Lorentz force fundamentally alters the flow field dynamics. This modification yields a more uniform temperature distribution and reduces velocity gradients between the symmetric center and edge regions, thereby promoting the transition to a linear solidification front essential for synchronous solidification and deformation across the entire plate width. Furthermore, variations in magnetic field intensity and frequency critically influence vortex flow position and density within the cast-rolling zone. The optimization goal was to maximize the angle α between the side surface and solidification front, which characterizes the linearity of the front. With optimized parameters of 0.49 T magnetic field intensity and 8 Hz frequency, angle α reaches 65°. This marks a 62.5% increase compared to the conventional (non-magnetic) cast-rolling scenario and achieves a near-linear (“1”) solidification profile. Full article

During a vehicle’s approach to a stop, significant longitudinal impact and pitch oscillations occur due to the decrease in vehicle speed and the substantial nonlinearity of the electro-hydraulic braking (EHB) system. To balance comfort and control accuracy at the end of braking, this paper proposes a comfort braking control strategy based on deceleration evolution characteristics. This method utilizes the adjustable pressure characteristics of the EHB system to construct an adaptive PI (proportional-integral) controller based on fuzzy rules, achieving a smooth transition between normal braking and comfort braking without mode switching. Simultaneously, target deceleration planning is introduced to gradually reduce the vehicle’s deceleration during the approach to a stop. Simulation and real-vehicle test results show that at initial speeds of 36 km/h, 40 km/h, and 44 km/h, the longitudinal deceleration impact amplitude is reduced by approximately 3.8%, 16.7%, and 11.7%, respectively. At 4 s, the vehicle pitch angle is reduced by 3.4%, 3.4%, and 3.8%, respectively. Meanwhile, the average braking distance change is less than 0.05%, and the maximum braking distance change is less than 0.1%. The results demonstrate that this strategy effectively improves braking comfort during the vehicle’s start-stop phase without compromising braking performance. Full article

Background: In 2016, Charles McMonnies advanced a theory positing that the use of scleral lenses might result in an elevation of intraocular pressure (IOP) due to the compression of the episcleral veins, consequently diminishing the eye’s capacity for draining aqueous humor. Alternative drainage pathways are capable of compensating only for 10–30% of the aqueous humor that requires drainage. Then it remains a quantity of fluid trapped in the anterior chamber. Recent data has demonstrated that the scleral lenses wear results indeed in an augmentation of the anterior chamber volume and a reduction of the iridocorneal angle, concomitant with a compression of Schlemm’s canal. Assuming that aqueous humor production remains constant, this imbalance between inflow and outflow can only lead to an increase in intraocular pressure. Methods: Several studies have attempted to answer this question over the past 10 years. Most authors have encountered the inherent difficulty of measuring IOP while the lens is still in place. Others were performed without waiting for the required time (>4 h of wear) for the lens to exert its maximum compression, thus minimizing their impact. Some attempted to assess IOP via the sclera (pneumotonometry), a technique known to give variable results and hard to reproduce. Ultimately, there are few reliable ways to assess IOP. One of them is by directly observing changes in the optic nerve structure over time. Results: These works indicate that there is indeed a moderate increase (<5 mmHg) in IOP. Could this be causing neuropathy and long-term negative impacts for patients who may be at risk? Based on the clinical experience of those involved in the field for many years, it is unlikely that IOP variations may have an impact on a healthy optic nerve. However, glaucoma patients or those at risk could be adversely affected in the long term. Conclusions: It is still too early to determine, without a doubt, the actual impact of the likely increase in IOP resulting from the structural changes caused by wearing scleral lenses Further work is therefore urgently needed to document these longitudinal changes. Full article

Background and Objectives: Long spinal fusion terminating at L5 remains controversial because of the risk of postoperative junctional failure. Although degeneration of the residual L5–S1 disc has been suggested as a contributing factor, the relative impact of disc degeneration versus sagittal spinopelvic alignment on different junctional failure patterns has not been fully clarified. Materials and Methods: This retrospective cohort study included 47 patients aged ≥60 years who underwent ≥5-level thoracolumbar fusion ending at L5 with a minimum follow-up of 2 years. Junctional failures were classified as proximal junctional failure (PJF) or distal junctional failure (DJF). Preoperative L5–S1 disc degeneration was assessed using modified Weiner and Pfirrmann classifications. Spinopelvic parameters were measured preoperatively, postoperatively, and at final follow-up. Junctional failure–free survival was analyzed using the Kaplan–Meier method, and risk factors were explored using Cox proportional hazards models. Results: Junctional failures occurred in 28 patients (59.6%), including 16 PJFs (34.0%) and 10 DJFs (21.3%). Lower grades of L5–S1 disc degeneration (Weiner grades 0–1) were more frequently associated with PJFs, whereas higher grades (≥2) were predominantly associated with DJFs (p = 0.024). Multivariate analysis showed that preoperative thoracolumbar kyphosis (hazard ratio [HR] = 1.164), preoperative T1 pelvic angle (HR = 1.269), and postoperative pelvic incidence–lumbar lordosis mismatch (HR = 0.877) as significant risk factors for PJF. Postoperative proximal junctional angle (HR = 0.899) and lumbar lordosis (HR = 0.920) were independently associated with DJF. Conclusions: Sagittal spinopelvic alignment parameters appear to have a greater influence on junctional failure patterns than residual L5–S1 disc degeneration in long fusions terminating at L5. Adequate sagittal correction should be prioritized to reduce the risk of both proximal and distal junctional failures. Full article

Impeller blades are one of the main parts of a centrifugal pump that affect the performance of the pump. The presence of solid particles in seawater, transported through a centrifugal pump, causes wear in the blade surface that reduces blade lifetime. In the orthogonal direction, this wear is an erosion thickness of the blade. Assuming that these particles have a spherical shape, the erosion rate depends on their velocity, size, impingement angle, and material hardness index. In this work, we investigate the erosion thickness of a low-head centrifugal pump operating in pump and turbine modes, with a particle radius ranging from 4 μm to 50 μm. The numerical simulation used an RNG k–ε turbulence model, assuming a perfect bounce collision between the particle and the rotating solid wall. The study shows that the blade pressure side is impacted by a solid particle concentration higher than the suction side. In pump mode, the erosion thickness on the blade sides increases if the particle radius is above 4 μm and reaches a maximum at 40 μm. In turbine mode, the erosion thickness decreases when the particle radius is greater than 5 μm. The thickness loss is greater in turbine mode than in pump mode. The influence of particle flow rate was investigated. Below a particle radius of 10 μm, particles follow the flow directions and reside for a longer time in the blade channel. Passing from a particle radius of 50 μm to 100 μm, the blade lifetime was decreased by a factor of 11. Full article

Thermoplastic hybrid composites reinforced with flax and glass fibers offer a sustainable, high-performance alternative for structural applications by balancing stiffness and energy absorption. This study investigated the impact of low-pressure plasma treatment on the thermal, mechanical, and microstructural properties of two polypropylene-based laminate configurations, PFGFP (polypropylene–flax–glass–flax–polypropylene) and PFGGFP (polypropylene–flax–glass–glass–flax–polypropylene), to optimize fiber–matrix interfacial adhesion. Materials were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile testing, and scanning electron microscopy (SEM). The plasma treatment significantly enhanced the lignocellulosic fibers’ surface energy, reducing the flax contact angle from 93.5° to 56.1°. DSC analysis revealed a matrix crystallinity of 35.41%, while TGA confirmed flax thermal stability up to 250 °C. The PFGFP configuration exhibited superior mechanical performance (Tensile strength = 61.69 MPa; Young’s modulus = 518.62 MPa), attributed to its symmetric architecture and efficient fiber impregnation. Conversely, PFGGFP showed reduced strength and microstructural voids due to incomplete wetting in dense reinforcement regions. These findings conclude that the synergy between plasma surface modification and optimized laminate architecture is critical for the design of high-performance sustainable composites, providing an objective basis for improving interfacial compatibility in hybrid systems. Full article

Musculoskeletal disorders, particularly in the neck and back, are prevalent across various professions, stemming from prolonged static postures and awkward neck flexions. This study investigated the efficacy of a passive exoskeleton, designed to alleviate musculoskeletal neck and back strain, in a simulated neck flexion task. Ten participants performed tasks involving neck flexion at angles of 15°, 30°, 45°, and 60°, both with and without the exoskeleton. Additionally, the impact of using a headlight was evaluated at a 45° neck flexion angle. Wearable electromyography sensors were used to quantify muscle activity as an indicator of neuromuscular loading, while subjective discomfort was assessed using the Rate of Perceived Exertion scale, and endurance times were recorded. The results demonstrated significant reductions in neck and lower back muscle activity (median values up to 31.0%) and perceived discomfort (median values up to 50.0%), with the most improvements at 30° and 45° neck flexion angles. Participants reported 50% higher endurance time when using the exoskeleton. Minimal benefits were observed at 15° flexion, likely due to reduced musculoskeletal demand at this angle. These findings highlight the potential of exoskeletons as an ergonomic intervention to mitigate neck and back strain in occupations where high degrees of neck flexion are prevalent. Full article

The wind and wave-induced Doppler shift (WDS) significantly affects the accuracy of ocean surface current fields retrieved from synthetic aperture radar (SAR). Understanding how different factors affect WDS is therefore essential for improving current inversion accuracy. Existing studies have predominantly focused on single-band WDS, mainly in the C-band, while investigations across other radar bands remain limited. In this study, we simulate the dynamic ocean surface height field and velocity field, and the radar backscatter from the ocean surface that includes the effect of breaking waves. Based on the Doppler shift theory of ocean surface motion proposed by Chapron, we develop a WDS simulation model with potential applicability to multiple radar bands. The performance of the model is verified by comparing its results with those from the CDOP, KaDOP and KuMOD models. The correlation coefficient between the proposed model and the CDOP model reaches 0.97, with mean deviation (MD), mean absolute error (MAE), and root-mean-square error (RMSE) not exceeding −2.07 Hz, 3.35 Hz, and 4.49 Hz, respectively. For comparisons with the KaDOP model, the correlation coefficient is 0.93, and the MD, MAE, and RMSE are within −21.23 Hz, 42.37 Hz, and 52.20 Hz. For comparisons with the KuMOD model, the correlation coefficient is 0.98, and the MD, MAE, and RMSE are within −2.60 Hz, 7.13 Hz, and 9.08 Hz. These results demonstrate that the proposed model can effectively predict the WDS for both C-, Ka-, and Ku-band radar returns. Furthermore, we investigate the impacts of radar parameters, including frequency band, polarization, and incidence angle, as well as wind field forcing on WDS, showing the model’s applicability across multiple radar bands. Finally, the proposed model is applied to current retrieval using Sentinel-1 ocean (OCN) data, and the inversion accuracy is assessed against collocated high-frequency (HF) radar observations. The MD, MAE, and RMSE of the current retrieval using the proposed model are −0.04 m/s, 0.26 m/s, and 0.32 m/s, which are close to those from the CDOP-based retrieval (MD, MAE, and RMSE of −0.02 m/s, 0.25 m/s, and 0.30 m/s). These results demonstrate that the proposed model performs well in ocean surface current inversion and shows potential for further application to ocean current retrieval based on radar data across different frequency bands. Full article

Nucleation remains one of the least understood steps during protein crystallization, although it strongly impacts product quality attributes, including total crystal numbers, final crystal size distributions, and thus downstream processing. In this work, the nucleation behavior of Lactobacillus brevis alcohol dehydrogenase (LbADH) wild type (WT) and five mutants (Q207D, Q126H, K32A, D54F, and T102E) is investigated in a stirred 7 mL crystallizer monitored by in situ multi-angle dynamic light scattering (MADLS). Nucleation was studied with highly pure homotetrameric LbADHs by establishing a crystallization, lyophilization, and re-solubilization protocol combined with size exclusion chromatography (SEC) and size exclusion high-performance liquid chromatography (SE-HPLC), yielding tetramer purities above 94% and removing low molecular weight impurities. During stirred batch crystallizations initiated by the addition of polyethyleneglycol 550 monomethyl ether (PEG 550 MME), SEC and SE-HPLC revealed decreasing tetramer peak areas but essentially constant peak apex positions, indicating that no long-lasting oligomeric intermediates accumulate at detectable levels. Time-resolved MADLS measurements using a custom-made flow-through cuvette in a bypass to the stirred crystallizer uncovered transient cluster populations. All protein variants exhibited an initial tetramer peak, followed by the formation of larger aggregates and a rapid rise in signal above a hydrodynamic diameter of 1000 nm, coinciding with the onset of macroscopic turbidity. A simple mesoscale nucleation model was formulated, yielding end-of-nucleation times, crystallized fractions, critical soluble concentrations, and apparent nucleation rate constants. The crystal contact mutations modulate both the timing and magnitude of the nucleation burst (rapid build-up of nuclei/cluster populations). The mutant Q207D showed strongly attenuated nucleation compared to the WT, whereas the other mutants (K32A, D54F, and particularly T102E) display markedly accelerated nucleation at nearly invariant critical concentrations. The combined workflow demonstrates how in situ MADLS, together with a tailored kinetic description, can provide mechanistic insight into protein nucleation in stirred batch crystallizers. Full article

Seawater flotation is increasingly adopted to reduce freshwater demand; however, its complex ionic environment often deteriorates sulfide mineral floatability and necessitates effective regulation strategies. In this work, seawater magnetization and collector magnetization were evaluated as two independent treatment routes affecting chalcopyrite flotation, and their impacts on flotation performance and interfacial properties were quantified. Pure-mineral flotation tests were conducted at pH 8 using butyl xanthate as the collector and pine oil as the frother, with magnetic field strength and magnetization duration varied in a controlled manner. Both flotation recovery and interfacial responses exhibited a distinct parameter-window behavior, rather than a monotonic enhancement. Under magnetized seawater conditions, chalcopyrite recovery increased from 80.45% to 92.7% at 200 mT and 8 min, while magnetized collector treatment under identical conditions produced a stronger enhancement, yielding a maximum recovery of 96.5%. Contact-angle measurements demonstrated an increase in chalcopyrite surface hydrophobicity within the effective magnetization range, whereas zeta-potential measurements revealed a positive shift toward less negative values, indicating weakened electrostatic repulsion in the seawater system. The consistent trends among flotation recovery, surface wettability, and surface electrical properties suggest that magnetization influences chalcopyrite floatability by modifying the balance between hydrophobic surface stabilization and electrostatic interactions, thereby highlighting an effective operating window for seawater flotation systems. Full article