Search Results (5,599)

Deep coalbed methane (CBM) has become an important contributor to natural gas production worldwide. Its fluid occurrence characterized by high free gas content and low water saturation suggests substantial gas-driven displacement caused by hydrocarbon generation overpressure. However, the microscopic evolution of this process and the corresponding occurrence remain poorly understood. To address these issues, we combined centrifugation experiments, nuclear magnetic resonance (NMR) monitoring, and theoretical modeling to systematically investigate pore-scale displacement dynamics and the associated fluid distribution. A dynamic evolution model for gas–water displacement in nanopores is developed by incorporating the capillary pressure and disjoining pressure, and validated against the centrifugation experimental data. At the pore scale, gas–water displacement is governed by critical displacement pressure and water film thickness. Water saturation declines sharply once the displacement pressure exceeds a critical threshold, after which it decreases slowly as the water film progressively thins. At the porous media scale, water saturation continuously decreases with increasing displacement pressure. For the high-rank coal samples in this study, the overall water saturation decreases to 49.15% as the displacement pressure increases to 10 MPa. The water film is negligible for pores larger than 20 nm, but significant for pores smaller than 20 nm. This critical pore size is not fixed, but is a dynamic threshold controlled by the disjoining pressure parameter. The occurrence of free gas in deep CBM is governed by the relative matching between hydrocarbon generation overpressure and reservoir pore structure. These findings provide a theoretical basis for resource assessment and efficient development of deep CBM. Full article

The solidification behavior and microstructural evolution of Al–Ge microparticles were investigated on Si, SiO₂, Al₂O₃, amorphous carbon, and ZrO₂ substrates. Micrometer-sized particles with a hypereutectic composition were produced by melting and resolidifying 40 nm thick Al–Ge films. Their size, wetting angle, crystal structure, and internal morphology were characterized by SEM and TEM techniques. We demonstrate that Al–Ge particles exhibited strongly substrate-dependent wetting, with contact angles ranging from 46° on SiO₂ to 123° on ZrO₂. Nevertheless, all particles developed a similar internal microstructure consisting of a fully interconnected, irregular Ge network within an Al matrix, indicating complete phase separation during solidification. The eutectic network was quantified by its ligament thickness. No correlation was found between ligament thickness and substrate type or contact angle, indicating that the coral-like internal Ge network forms independently of particle wetting. Instead, the ligament thickness increased with particle size and during post-solidification annealing. The network gradually coarsened up to 310 °C, followed by its complete breakdown and transformation into an equilibrium Janus morphology at 370 °C. These findings provide new insight into the solidification of irregular eutectic systems and suggest a route for tailoring three-dimensional internal microstructures in eutectic microparticles. Full article

The microstructure of semicrystalline bioresorbable polymers is central to their biomedical performance because the crystalline content influences both the mechanical stability and the degradation behaviour. Experimental studies have shown that crystallinity evolves concurrently with mass loss during enzymatic degradation. However, most existing models represent the material as a single homogeneous structure, preventing them from capturing this microstructural evolution or the state-selective mechanisms that drive it. We present a one-dimensional partial differential equation model for the enzymatic degradation of thin films, which treats the crystalline and amorphous states as distinct reactive components. Calibrated to poly($\epsilon$-caprolactone) (PCL) degraded by Candida antarctica lipase in vitro, the model accurately reproduces both the observed weight-loss profile and the concurrent decline in crystallinity. Parameter uncertainty analysis indicates that while there are varying degrees of confidence in individual parameter values, the overall model predictive uncertainty is well constrained. Parameter sensitivity analysis shows that the amorphous catalytic rate (the rate at which the enzyme degrades the amorphous region) is the dominant driver of degradation dynamics. The identified model parameters are used to explore the role of film thickness on the rates of mass and crystallinity loss. It was found that thin films remain largely reaction-limited, whereas thicker specimens become increasingly transport-influenced, with slower degradation and delayed structural evolution in the material interior. The model provides a useful tool to explore the effect of changing PCL film thickness on degradation rate and crystallinity-related properties without extensive experimentation. Full article

Gel plugging agents are key drilling fluid additives for maintaining wellbore stability. However, the downhole ultra-high-temperature, high-salinity environments, and developed micro-fractures in deep and ultra-deep wells pose severe challenges to the performance of gel plugging agents. To address this problem, this paper presents the preparation of a nano-micron gel plugging agent with a core–shell structure, denoted as LMS, suitable for high-temperature and high-salinity water-based drilling fluids. LMS was synthesized via emulsion polymerization, using a styrene–sodium p-styrenesulfonate copolymer as the core and 2-acrylamido-2-methylpropanesulfonic acid and methacryloyloxyethyltrimethyl ammonium chloride as the shell-modifying monomers. LMS was characterized by infrared spectroscopy, thermogravimetric analysis, transmission electron microscopy, and particle size analysis, confirming that LMS met the design expectations. Experimental results showed that after aging at 220 °C for 16 h under saturated-salt conditions, the filtration loss of the drilling fluid with 3 wt% LMS was 10.4 mL, a reduction of 57.4% compared to the base mud. Meanwhile, LMS exhibited good plugging performance in microporous membrane tests and sand bed tests. After aging at 220 °C for 16 h under saturated-salt conditions, the core plugging rate reached 95.4%. LMS can not only adsorb onto clay surfaces to increase the thickness of the hydration film, enhancing drilling fluid stability, but can also synergistically build a filter cake with clay particles to plug nano-micron pores, preventing drilling fluid infiltration into the formation. This paper provides a preparation method for a high-temperature- and high-salinity-resistant gel plugging agent with excellent plugging effects, which is expected to support safe and efficient drilling in deep and ultra-deep formations. Full article

Picosecond laser drilling is characterized by a minimal heat-affected zone (HAZ) and superior surface quality, making it widely utilized for fabricating film-cooling holes in aeroengine turbine blades. However, maintaining consistent drilling quality remains a significant challenge. This study conducts picosecond laser trepanning drilling experiments on a GH4169 nickel-based superalloy to investigate the quality of inclined holes. Due to its excellent high-temperature resistance, creep resistance, and corrosion resistance, GH4169 is a primary material for turbine blades. A control variable method was employed to evaluate the effects of power ratio (60–95%), number of scanning passes (5–40), and defocus amount (−0.2 mm to 0.2 mm) on the quality of inclined holes with tilt angles of 7° and 15° and a sample thickness of 0.5 mm. Entrance diameter, exit diameter, and taper angle were utilized as the key quality indicators. The results indicate that due to the distribution of laser energy flux, both the geometric dimensions and taper angles of 15° inclined holes are significantly larger than those of 7° holes. As the power ratio increases, the entrance and exit diameters exhibit non-linear expansion; a “topographic stability window” is achieved at a 75% power ratio due to the equilibrium in energy coupling. An increase in the number of scanning passes leads to larger diameters; however, excessive scanning slows down the expansion of the exit diameter due to multiple reflection losses within the hole and the accumulation of slag, thereby intensifying taper evolution. The defocus amount exerts a bidirectional regulatory effect: positive defocusing increases the entrance diameter while decreasing the exit diameter, whereas negative defocusing facilitates the expansion of the exit. Optimal hole wall quality is observed at zero defocusing. This work provides data support for parameter optimization and the selection of inclination angles in subsequent laser machining of inclined holes. Full article

Taking arc-shaped bent pipes as the subject of study, a three-dimensional dynamic spraying numerical model based on Euler–Euler approach and a wall film formation model was developed through numerical simulation and experimental validation. The effects of geometric parameters, such as the bending radius and pipe diameter, on the distribution of coating thickness were systematically investigated. Numerical simulations were used to reproduce the motion of gas–liquid two-phase flow and the evolution of spray film formation, and the reliability of the model was verified experimentally. The results indicate that the film thickness distribution for axial spraying exhibits good stability, whereas circumferential spraying shows significant position dependence due to differences in local curvature and the angle of incidence. In addition, increased curvature in convex areas reduces the peak film thickness and widens the spray pattern, while concave areas enhance localized deposition, resulting in a narrower distribution of the coating. Spray coating experiments conducted on flat and bent pipe confirmed that the film thickness distribution trends and peak locations predicted by the model were in good agreement with the experimental results. This study provides a theoretical basis and practical guidance for spray trajectory planning and film thickness control in complex curved components. Full article

Few-layer hexagonal boron nitride (hBN) is a promising two-dimensional dielectric for electronic and neuromorphic devices. However, its practical deployment is often hindered by the thickness nonuniformity of as-grown samples and by defects introduced during the transfer-stacking process of assembled samples. In particular, the influence of the initial hBN quality on the final stacked-film quality remains insufficiently understood. Here, we report a wafer-scale strategy for fabricating high-quality few-layer hBN based on ultraflat single-crystal hBN (USC-hBN) monolayers. Compared with transfer-stacked hBN grown on Cu foil (rough hBN), stacked few-layer USC-hBN shows a much lower surface roughness and a drastically reduced wrinkle density, indicating superior flatness and interfacial cleanliness. Furthermore, memristors fabricated from six-layer USC-hBN exhibit clearer resistive-switching behavior and a higher ON/OFF ratio than those based on rough hBN, owing to the more uniform surface/interface. These results demonstrate that source-material flatness is a critical determinant of transfer-stacked hBN quality and device performance. This work provides an effective route toward reliable integration of high-quality two-dimensional dielectric films. Full article

Aerostatic spindles are indispensable in the ultra-precision manufacturing field due to their high accuracy and low friction. However, rotor manufacturing errors will affect the thickness and uniformity of the air film, thereby limiting the improvement and application of the aerostatic spindle. To explore this issue, this paper presents theoretical modelling and experimental work. Rotor cylindricity errors were first evaluated based on manufacturing errors, and a calculation model of the film thickness considering rotor cylindricity errors was established. By solving the dynamic Reynolds equation considering cylindricity errors, the dynamic stiffness and damping of aerostatic spindles were obtained. The influence mechanism of rotor cylindricity errors on the dynamic stiffness and damping coefficients of the rotor–bearing system was revealed. The stiffness coefficients K_xx, K_yy, and K_xy are more sensitive to the saddle-shaped errors, and the stiffness coefficient K_yx and both damping coefficients are more closely related to bucket-shaped errors. Regarding the influence of the cylindricity errors’ extremal position, the main and cross stiffness coefficients are sensitive to saddle-shaped errors and bucket-shaped errors, respectively; the main and cross-damping coefficients are sensitive to bucket-shaped errors. Under the effect of three kinds of error shapes, when the rotor cylindricity errors value is less than 1 μm, the dynamic stiffness and damping coefficients are conducive to improving the dynamic characteristics of the rotor–bearing system. Multiple rotors were manufactured, and their cylindricity errors were measured, and then the dynamic characteristics of the assembled aerostatic spindles with these rotors were tested. It was found that the dynamic stiffness of spindles with saddle-shaped errors is larger than that of spindles with conical-shaped errors, and the greater the error values are, the worse the rotation accuracy. The experimental results are consistent with the theoretical findings, thus verifying the feasibility and validity of the established theoretical model. This study improves the error tolerance design accuracy of rotors and thereby enhances the dynamic performance of aerostatic spindles. Full article

In the context of the increasing demands of precision manufacturing and nanotechnology, especially for emerging fields such as Oxide oxide films in Nuclear nuclear fuel assemblies, the measurement of multi-layer inhomogeneous thin films faces significant challenges. Traditional spectroscopic interference thickness measurement techniques have limitations in handling dispersion interference, parameter coupling, and the efficient solution of nonlinear inverse problems. This study proposes a new model that integrates deep learning and physical model fitting. It constructs a theoretical model of multi-layer thin-film interference spectroscopy based on the Lorentz–Drude formula, uses a generative adversarial network (GAN) for initial structure analysis, and builds a two-layer optimization framework of “deep learning rough positioning—physical model fine fitting”. The research aims to break through the limitations of traditional methods, improve measurement accuracy and anti-noise ability, and provide a key technical support for emerging fields. Full article

Background/Objectives: The aim of this study was to investigate the effects of intraocular pressure (IOP)-lowering drops on the sublayers of the human tear film as assessed by a novel nanometer-resolution Tear Film Imager (TFI, AdOM, Israel). Methods: In a prospective, cross-sectional study, 98 eyes from 56 adult human subjects were imaged using the TFI. The dataset included data from 18 eyes from 12 subjects treated with preserved IOP-lowering drops and 80 eyes from 44 control subjects not under ocular hypotensive therapy. Subjects in the IOP treatment group used a variety of IOP-lowering medications, including prostaglandin analogs, beta-blockers, carbonic anhydrase inhibitors, alpha agonists, and combination drops. A linear mixed effects model was used to assess the association between IOP-lowering therapy and tear film (TF) metrics, controlling for age and intra-individual correlation. The following parameters were measured: muco-aqueous layer thickness (MALT), muco-aqueous layer thinning rate (MALTR), lipid layer thickness (LLT), lipid map uniformity (LMU), inter-blink intervals (IBI), and lipid break-up time (LBUT). Results: Average ages significantly differed (p = 0.013) between the treatment group (66.5 years) and control group (average age 51.5 years), and thus results were adjusted for age accordingly. IOP was 17.1 mmHg in the treatment group and 16.1 mmHg in the control group. When analyzing the sublayers of the TF, MALTR had a significant association with IOP-lowering therapy after adjusting for age, with a difference of −52.68 nm/s; 95% confidence interval [−96.87, −8.48]; p-value = 0.020. Additionally, IBI was significantly associated with IOP-lowering therapy after log transformation (p = 0.049), with shorter IBI in the treatment group. All other metrics (MALT, LLT, LMU, and LBUT) were statistically insignificant (p > 0.05). Conclusions: These pilot results suggest that IOP-lowering drops may accelerate thinning of the TF, specifically the muco-aqueous layer. Longitudinal studies with significantly larger samples are needed to specify the differential impact of various ocular hypotensive therapies on the human TF and the clinical implications of these findings. Full article

Dry eye disease (DED) is a complex ocular surface disorder characterized by tear film instability, chronic inflammation, and epithelial damage, for which current treatments remain limited. Marine-derived bioactive oligosaccharides have attracted increasing interest due to their diverse pharmacological activities and favorable safety profiles. In this study, we investigated the therapeutic potential of neoagarotetraose (NA4), a marine oligosaccharide derived from red algal agar, in a murine model of DED. DED was induced in eight-week-old female C57BL/6 mice by topical instillation of 0.2% benzalkonium chloride for seven consecutive days. NA4 was administered topically at concentrations of 125, 250, and 500 mg/L. Therapeutic outcomes were evaluated by tear secretion, corneal fluorescein staining, histopathological analysis, immunofluorescence staining for Ki67, F4/80, IL-1β, IL-6, and TNF-α, TUNEL assay for apoptosis, and ELISA for cytokine levels. NA4 treatment significantly improved tear secretion and reduced corneal fluorescein staining scores. Histological analysis revealed that NA4 preserved corneal epithelial thickness and restored conjunctival goblet cell density. Immunofluorescence analysis revealed that NA4 reversed inflammation-associated epithelial hyperproliferation and attenuated macrophage infiltration. Moreover, NA4 markedly suppressed the expression and tissue levels of IL-1β, IL-6, and TNF-α, and attenuated corneal epithelial apoptosis, with the 500 mg/L NA4 group showing no significant difference in efficacy compared to the positive control 0.1% sodium hyaluronate. These findings demonstrate that NA4, a marine-derived oligosaccharide, exerts multi-targeted protective effects against DED by improving tear film stability, preserving ocular surface integrity, suppressing inflammation, and reducing apoptosis. Our study highlights the potential of marine oligosaccharides such as NA4 as promising candidates for ocular surface disease management and supports the further exploration of marine resources for ophthalmic therapeutic applications. Full article

Ultrathin ferrimagnetic heterostructures have emerged as promising platforms for next-generation spintronic devices, yet the role of two-dimensional substrates in modulating their magnetic properties remains underexplored. Here, we report a comprehensive study of the thickness- and temperature-dependent magnetic behavior of amorphous Fe₇₃Co₈Gd₁₉ films (4–32 nm) deposited on Si, WSe₂ bilayer, and WSe₂ monolayer substrates. Structural integrity and stoichiometry were confirmed via X-Ray Diffraction (XRD), X-Ray Reflectivity (XRR), Raman spectroscopy, and Energy-Dispersive Spectroscopy (EDS) analysis. In-plane magnetometry from 10–300 K reveals that monolayer WSe₂ promotes stronger interfacial spin alignment, with the 4 nm film exhibiting a sharp increase in coercivity below 50 K, where $H_c$ exceeds 23 mT and even surpasses thicker counterparts, alongside enhanced saturation magnetization (∼790 kA/m at 100 K). This dramatic enhancement of coercivity is the most significant result of this work, underscoring the dominant role of interfacial coupling in governing low-temperature magnetic hardness. Conversely, films on bilayer exhibit suppressed magnetization and soft magnetic behavior ($H_c$ < 10 mT) across all temperatures, making them attractive for ultralow-power and high-speed spintronic applications. These findings demonstrate that atomically thin WSe₂ interfaces can modulate coercivity, magnetization, and squareness through proximity effects, establishing a tunable and thermally stable platform for spintronic device applications. Full article

Atmospheric ice accretion on transmission lines threatens the safe operation of power systems, whereas existing monitoring methods mainly focus on ice thickness, load, or morphology and provide limited material-related information for distinguishing ice types. This study investigates the dielectric response of ice and snow samples to evaluate its feasibility for preliminary ice-type discrimination. Artificial glaze ice and natural snow samples were measured using a self-built temperature-controlled parallel-plate system within 10–100 kHz. The effects of freezing-water conductivity, temperature, surface water film, and snow density were examined, and representative glaze ice, dry snow, and wet snow samples were further compared under the same measurement framework. The results show that the dielectric constant generally decreases with frequency, while conductivity, water film, and density mainly increase the response magnitude and, in some cases, alter the prominence of loss-related features. These trends are consistent with reported dielectric dispersion, conductive loss, and snow density-related mixing behavior. Dielectric loss provides clearer differences between glaze ice and snow-related samples than dielectric constant alone, whereas dry and wet snow require combined consideration of dielectric constant and loss. A preliminary two-step hierarchical framework is therefore proposed for the tested sample set. Further validation over broader frequency ranges and conductor-like geometries is required before practical application. Full article

The design of metal nanoparticle-on-a-mirror (NPOM) provides a powerful strategy for optical enhancement in gap plasmonics. Here, we report a systematic numerical study on an NPOM structure composed of gold nanocubes (GNC) and a continuous gold film via the finite element method (FEM). First, we simulated the near-electric field distribution of isolated GNC in a homogeneous medium and compared it with that of the GNC-based NPOM structure, revealing the dominant role of plasmon coupling in the gap region. Second, we systematically investigated the influence of the thickness of the dielectric layer between the GNC and the gold film on the optical enhancement characteristics in the gap region. The results show that the maximum electric field intensity of the resonance peak decays rapidly when the thickness of the dielectric layer is less than 2 nm, decreasing from 5048 (t = 0.5 nm) to 1032 (t =2 nm). Third, we further investigated the influence of the polarization angle of the incident light on the optical enhancement in the gap region. Finally, the dielectric environment n₀ and the refractive index n of the dielectric layer were studied. This work elucidates the unique gap plasmon coupling mechanisms of GNC-based NPOM structures and provides a precise tuning strategy for key structural and optical parameters, endowing the structure with important application prospects in sensing, energy conversion, and photodetection. Full article

With the continuous advancement of display technology and advanced integrated circuits, oxide thin-film transistors (TFTs) have become core devices due to their high mobility, low leakage current and excellent large-area uniformity. To achieve low power consumption, high performance and high reliability, the introduction of high-k gate insulating layers is crucial. Among the numerous high-k materials, hafnium oxide (HfO₂) has attracted significant attention due to its excellent dielectric properties and good compatibility with CMOS processes. In this paper, uniform and dense HfO₂ films were successfully fabricated using the sol–gel method to serve as insulating layers for TFT devices. Through experimental analysis, 400 °C was determined to be the optimal annealing temperature. At this temperature, the effects of replacing SiO₂ with HfO₂ as the insulating layer, as well as the impact of reducing film thickness, on TFT devices were investigated. Ultimately, at an annealing temperature of 400 °C, an 85 nm-thick HfO₂ film achieved the highest on/off current ratio (I_on/off = 1.11 × 10⁶), the lowest subthreshold swing (SS = 0.53 V/dec), the lowest threshold voltage (Vth = −1.1 V) and the lowest off-current ratio (I_off = 2.5 × 10⁻¹² A). It was confirmed that replacing SiO₂ with HfO₂ as the insulating layer is a viable approach for reducing the volume of TFT devices. Full article