Search Results (1,892)

The paper investigates the possibility of small hydrogen (SH) formation in the early Universe during an interval of about 10–80 s after the Big Bang. Assuming that SH exists as proposed by the author earlier, the current study examines the cosmological conditions under which the SH can be formed and survive. The photon, baryon, and electron–positron pair densities are estimated, together with the corresponding thermal energies and temperatures, and the formation cross section required to obtain a specified SH abundance and the maximum destruction cross section consistent with SH survival are derived. Although the microscopic formation and destruction cross sections are not presently known, phenomenological constraints the cross sections must satisfy are derived for a given SH abundance. The study suggests that, if SH exists and has negligible nuclear interactions, it would not significantly participate in the standard Big Bang nucleosynthesis reaction network. The possibility that SH can undergo early cosmological decoupling, subject to the presently unknown momentum-transfer cross sections, is also discussed. If SH is formed in sufficient abundance and decouples sufficiently early, it can provide an interesting mechanism for early structure formation and may potentially contribute to the formation of black-hole seeds. This study does not establish the existence of SH, but rather examines whether the conditions in the early Universe present immediate cosmological obstacles to SH formation and survival. Full article

Poly(acrylic acid)-based superabsorbent polymer (PAA-SAP) rapidly absorbs water and swells during pipeline transport in mine water-based inhibitor fluids, increasing flow resistance and potentially causing blockage. To improve aqueous structural stability, PAA-SAP beads were coated with poly(vinyl alcohol) (PVA) by rotary spraying and hot-air curing, with borax introduced to regulate the coating structure. The effects of PVA concentration, coating thickness, temperature, and hydrodynamic disturbance were evaluated using stability tests, scanning electron microscope (SEM), energy-dispersive X-ray spectrometer (EDS), fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), dry-film swelling, and mass-loss analyses. A 10% PVA formulation showed favorable film-forming and processing performance. Increasing coating thickness prolonged structural retention, whereas higher temperature and stronger disturbance accelerated hydration and failure. At 0.30 mm coating thickness and 2.5 m·s⁻¹ laboratory hydrodynamic disturbance parameter, the borax-modified PVA coating failed after approximately 16 min, compared with 10 and 12 min for PVA and PVA/poly(vinylpyrrolidone) (PVP) coatings, respectively. Boron incorporation and possible boron–oxygen interactions restricted chain mobility and improved coating compactness and stability. A power-law model based on 46 datasets showed good interpolation performance (Coefficient of determination (R²) = 0.9421; Mean Absolute Percentage Error (MAPE) = 5.44%). Failure involved swelling, gelation, network weakening, cracking, and chain dissolution, with core swelling potentially promoting crack propagation. These findings support coating-parameter selection and subsequent mine-scale pipeline validation. Full article

Microvehicles, such as e-scooters and bicycles, are increasingly used in urban transport systems. Existing models were primarily developed either for pedestrians-only or motor vehicles-only and cannot fully capture the dynamics of microvehicles, particularly when they operate in shared spaces also used by pedestrians. This paper proposes a hybrid microscopic modeling framework for microvehicles’ and pedestrians’ trajectories based on a combination of physical interaction principles and deep learning techniques. A Long Short-Term Memory (LSTM) model is developed using space discretization and interaction variables to predict user trajectories in shared environments. The proposed framework was evaluated using observations collected through a semi-controlled experiment conducted at the University of Patras. Nearly 300 participants generated 553 trajectories involving pedestrians, bicycles, and e-scooters that were used for model calibration and validation. The model achieved satisfactory trajectory prediction accuracy with an RMSE below 0.20 m in testing scenarios. The model was compared to an adapted Social Force Model (SFM) for microvehicle and pedestrian interactions and showed better performance. The findings highlight important behavioral differences between pedestrians, bicycles, and e-scooters in terms of interaction distances and fields of view. The proposed framework can support future applications in infrastructure design, safety assessment, and traffic management. Full article

The dust generated during coal mining poses a significant threat to miners’ health and safety. Surfactants, as effective agents for improving coal wettability, require a deeper exploration of their microscopic action mechanisms. This study systematically investigates the micro-interaction behaviors and wetting regulation mechanisms of four types of surfactants—anionic (SDBS), cationic (CTAB), zwitterionic (BS-12), and nonionic (AEO-9)—with lignite, bituminous coal, and anthracite through molecular simulations and dynamic contact angle experiments. To correlate the wettability differences with the physical and chemical properties of different coal ranks, XRD and SEM observations were employed to analyze the mineral composition and surface microstructure. The results demonstrate that SDBS has the strongest adsorption capacity on coal, with the wettability capacity ranked as follows: SDBS > CTAB > BS-12 > AEO-9. This research reveals the regulation mechanism of surfactants on coal wettability, providing a theoretical basis for optimizing dust prevention technologies and fostering the development of green mining. Full article

This study addresses abnormal cutter wear in H13 steel disc cutters during tunnel boring machine excavation of composite strata, where transient frictional shearing temperatures interact with environmental degradation. Taking the Xiangshan Tunnel at 160 m overburden depth as the engineering background, a coupled FLAC3D-PFC3D model was developed to resolve the coupled thermo-mechanical process, and a relative wear model based on the Holm method was formulated to incorporate sub-microscopic microstructural damage and quantify wear evolution. Numerical simulations elucidated the coupled thermal evolution mechanism at the cutter–rock interface. Systematic analyses were performed on single-cutter wear under coupled cutting temperature–chemical corrosion and cutting temperature–freeze–thaw cycling, together with the total wear for single-, double-, and triple-cutter configurations. Under temperature–chemical corrosion coupling, the peak wear coefficient of H13 steel reached 1.45 at 600 °C and pH 6. Under temperature–freeze–thaw cycling coupling, H13 steel peaked at 1.75 at 600 °C with 14 freeze–thaw cycles. Under triple-factor coupling, single-cutter wear was primarily influenced by freeze–thaw damage, double-cutter wear by penetration depth and chemical corrosion, and triple-cutter wear by cutter spacing and chemical corrosion. The chemical corrosion proportion in the double-cutter interface reached 89.4%. At 600 °C, thermal softening drastically amplified environmental degradation abrasion in the primary rock material. Chemical–thermal coupling exhibited greater influence than freeze–thaw cycling, and preferential chemical dissolution in the interface zone compressed the cutter parameter regulation space to its limit. The wear coefficient quantification and factor influence ranking reflect the multi-factor-coupled wear evolution in transportation tunnel composite strata. The parameter sensitivity data provides quantitative references for cutter replacement cycles, advanced parameter selection, and per-kilometer cost variations in tunnel construction management. Full article

Unsignalized mid-block raised crosswalks are widely used to improve pedestrian safety by prompting drivers to yield. However, on arterial roads they conflict with vehicular continuity, while their environmental effects remain insufficiently understood. This study uses field-informed microscopic simulations to examine these effects across the full range of pedestrian and vehicle influx. The raised crosswalk reduces the maximum traffic current by 42.6%, causing the system to exhibit three phases: quasi-free flow, jamming, and blocking. Quasi-free flow was the most relevant because it combined high throughput with frequent deceleration and re-acceleration under conditions observed during most of the operating day. In this phase, the mean instantaneous CO₂ emission rate increased by 23.08%, revealing a spatial asymmetry: emissions decreased by 35.66% upstream but increased by 51.87% downstream. NO_x and PM_x showed similar downstream patterns, whereas CO reflected upstream stop-and-go dynamics. Exploring a solution to this operational incompatibility, this study evaluated a zebra crossing controlled by a pedestrian-actuated signal. By coordinating pedestrian and vehicular right-of-way, this configuration reduced mean CO₂, CO, NO_x, and PM_x emission rates by 18.3%, 40.61%, 26.75%, and 38.96%, respectively. Overall, these findings highlight emissions as a critical evaluation criterion and provide decision-makers with evidence-based insights for assessing pedestrian infrastructure. Full article

Rare earth elements (REE) are critical to 21st-century technology, from electronics and defense applications to renewables and beyond. The processing of REE is primarily based on minerals (bastnasite, monazite, and xenotime), but alternative resources (coal ash, E-waste, and permanent magnets) are also gaining increasing interest. Adsorption remains one of the most efficient, environmentally friendly extraction methods despite its lengthy mixing time. In the present research article, a hemp biochar prepared by vacuum pyrolysis at 700 °C was examined for its applicability in the adsorption of selected REE (La³⁺, Nd³⁺, Dy³⁺) from synthetic solutions. An innovative technique, Resonant Vibratory Mixing (RVM), was applied to improve adsorption kinetics, with factors including time (5–30 min) and intensity (30–70%) at room temperature. Using the Thermo Scientific 4000 M shaker for mixing, the maximum adsorption capacities were 77.56 mg/g for Dy³⁺, 75.85 mg/g for La³⁺, and 72.65 mg/g for Nd³⁺ using 100 mg of hemp biochar and 10 mL solutions (1000 mg/L). The adsorption capacity of 100 mg hemp biochar was 79.79 mg/g for Dy³⁺, followed by 77.61 mg/g for La³⁺ and 75.75 mg/g for Nd³⁺, using RVM for only 40 min at 70% intensity. RVM increased the adsorption capacities of all REE in only 40 min. Surface and structural analyses were carried out using Scanning Electron Microscope (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer-Emmett-Teller analysis (BET), Zeta Potential, and Carbon/Hydrogen/Nitrogen (CHN) methods. The adsorption recoveries of all REE in the single-element system were higher than 98.5%. However, in a multi-element system, the adsorption recoveries of La³⁺, Nd³⁺, and Dy³⁺ were 83.7%, 96.2%, and 99.2%, respectively, demonstrating that hemp biochar has low selectivity for Dy³⁺ and Nd³⁺. The adsorption process could be well described by the Langmuir isotherm and the pseudo-second-order kinetic model, indicating monolayer adsorption and chemical process involvement. Based on the characterization analysis of hemp biochar, electrostatic interaction was the dominant mechanism in this study. REE desorption using 0.5 M nitric acid was the most efficient, with >80% of REE recovered. The combination of hemp biochar as an adsorbent and RVM as a mixing technique demonstrated excellent performance in synthetic solutions; the reusability and application of hemp biochar to natural solutions require further study. Full article

The influence of chitosan (CS) molecular weight on the interfacial architecture of Ti₃C₂T_x MXene (MX)/chitosan composites (CS/MX) was investigated using complementary spectroscopic and microscopic techniques. Two commercial chitosans with distinct molecular weights and degrees of deacetylation (DD) were evaluated, CS-1 (91 kDa, 73.05% DD) and CS-2 (153 kDa, 69.52% DD). Ti₃C₂T_x MXene was synthesized by selective etching of Ti₃AlC₂ and characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), and Raman spectroscopy. XPS and Raman analyses provided evidence for successful MXene formation through a 45.4% reduction in surface aluminum content, a substantial increase in fluorine-containing surface terminations, and the emergence of the characteristic A₁g(Ti,C) Raman mode at ~200 cm⁻¹. Composite membranes containing different MXene loadings (MX-25, MX-50, and MX-75) were prepared by vacuum-assisted filtration and characterized. Morphological and spectroscopic analyses revealed that the lower-molecular-weight chitosan promoted more effective intercalation between MXene layers, resulting in expanded accordion-like structures and greater surface accessibility. In contrast, the higher-molecular-weight chitosan formed a thicker polymer coating that partially encapsulated the MXene sheets. ATR-FTIR, Raman, and XPS results demonstrated that CS-MX composite formation was governed by non-covalent interactions, primarily electrostatic attraction between protonated chitosan –NH₃⁺ groups and negatively charged MXene surface terminations, reinforced by hydrogen bonding. These findings demonstrate that chitosan molecular weight is a key design parameter governing the interfacial architecture and surface accessibility of Ti₃C₂T_x-based composites. Full article

Water–rock interaction (WRI) due to fluid invasion into formation fractures causes potential formation damage during drilling in hot dry rock (HDR) reservoirs. Due to the developed artificial fractures, drilling fluids will contact and interact with HDR reservoir fractures, leading to alterations in fracture characteristics. With the increasing popularity of brine-based drilling and completion fluids, these alterations induced by WRI could be further enhanced, which requires investigations. In this study, short-term WRI experiments between the HDR and three reactive solutions, including pure water and alkaline (pH = 10) 6 wt% NaCl/KCl solutions, under temperatures of 25 °C and 180 °C, were carried out. Rock-surface topography alterations were identified using laser scanning. Morphological alteration mechanisms were revealed through microscopic and mineralogical alteration determination using a field emission scanning electronic microscope. Hydrogeochemical simulations, including reaction kinetics and equilibrium, were conducted to support the mineralogical alterations. Implications of morphological alterations on fracture permeability were demonstrated based on a roughness–permeability model. The results show that interactions with the alkaline NaCl solution cause the smoothening of the rock surface due to a coating effect of secondary silicate precipitations, while interactions with pure water and the alkaline KCl solution result in rock-surface roughening because of feldspar dissolution, differential mineral dissolution and biotite hydrolysis dispersion. The secondary precipitations either cover or fill the pores and cracks, the dissolved feldspar enlarges the pores and cracks, the differential mineral dissolution coarsens the rock surfaces, and the biotite hydrolysis dispersion generates pores and cracks on its surfaces. An increase or a decrease in surface roughness induces a corresponding increase or decrease in fracture permeability, because the roughness augmentation (roughening) enlarges seepage channel spaces while roughness reduction (smoothening) narrows them. This work reveals potential formation damage induced by drilling fluid invasion into fractures within HDR geothermal reservoirs, and provides theoretical insights for mitigating such damage. Full article

The efficient development of heavy oil reservoirs is challenged by the high viscosity and poor mobility of heavy oil. Although multicomponent thermal fluid technologies involving heat, gas, and chemical agents have demonstrated potential advantages over conventional steam-based recovery methods, the microscopic synergistic mechanisms responsible for viscosity reduction remain insufficiently understood. Therefore, this study investigates the synergistic mechanisms by which heat, an alkane solvent (C₁₁H₂₄), and CO₂ reduce heavy-oil viscosity. Heavy oil from the Shengli Oilfield was selected as the research object, and rheological experiments were combined with molecular dynamics simulations to systematically analyze viscosity variations and their underlying microscopic mechanisms under different conditions. The experimental results demonstrate that increasing temperature significantly reduces heavy oil viscosity, and a characteristic transition in viscosity reduction behavior occurs at approximately 100 °C. At 90 °C, the addition 5 wt% oil-soluble viscosity reducer C₁₁H₂₄ decreases the heavy oil viscosity to 442.2 mPa·s, corresponding to a reduction rate of 83%. The solubility of CO₂ increases markedly with pressure, and at 30 MPa, the viscosity reduction exceeds 99%. The combined effects of these three factors exhibit superior viscosity-reduction performance. Molecular dynamics simulation results indicate that CO₂ and the viscosity reducer synergistically weaken the π-π stacking interactions of asphaltenes and resins in heavy oil, transforming heavy components from locally aggregated states into more uniformly dispersed configurations. Meanwhile, the intermolecular interaction energy and cohesive energy density decrease, indicating weakened molecular interactions and enhanced diffusion behavior. These results demonstrate that the synergistic viscosity-reduction mechanism of heat–gas–agent systems is mainly associated with structural disaggregation, interaction weakening, and diffusion enhancement. This study provides molecular-level insights into multicomponent thermal fluid-assisted heavy oil recovery and offers theoretical support for improving heavy oil development efficiency. Full article

Despite developing on other fungi and forming complex ecological interactions, fungicolous fungi are among the understudied groups. This study examined the fungicolous fungi Hypomyces aurantius and its host species, Lyophyllum littoralis, in detail using morphological and molecular data. Both species are new records for the Turkish mycobiota. The macroscopic and microscopic characteristics of both species were evaluated in depth, and morphological descriptions were corroborated by molecular analyses based on the nuclear ITS region. It was observed that H. aurantius heavily colonised L. littoralis, a previously unreported host, causing significant softening and degradation of the host tissue. We investigated extracellular enzyme activities to determine the mycoparasitic activity of H. aurantius on the host fungus and its environmental survival strategies. We detected positive enzyme activities. These results suggest that H. aurantius is a potential mycoparasite. This study contributes to our understanding of fungal biodiversity in Türkiye and provides a foundation for understanding the ecology of supra-fungal fungi and fungicolous/mycoparasitic interactions. conclusions. Full article

Multiphase swirling flows in confined spaces induce highly destructive, nonlinear fluid–structure interaction (FSI) vibrations. Understanding the underlying physical mechanisms is critical for ensuring the safety of industrial operations. This study proposes a mesoscopic multiscale framework coupling the Multi-Relaxation Time Lattice Boltzmann Method with Large Eddy Simulation (MRT-LBM-LES) and the Flügge thin-walled cylindrical shell equations to analyze two-way FSI responses. Variational Mode Decomposition (VMD) and the Hilbert–Huang Transform (HHT) are employed to decouple non-stationary broadband excitation signals. The macroscopic topological evolution of the swirling air core—from initial depression to critical breakthrough—is accurately captured. Dynamic mapping reveals a strict time-domain phase-locking mechanism between macroscopic flow instability and microscopic high-frequency structural excitation caused by cavitation bubble collapse. Furthermore, a dimensionless cross-scale energy cascade index is defined to quantify energy transfer. Results indicate that while higher discharge flow rates delay the critical breakthrough, they trigger a delayed, high-amplitude step mutation in the energy cascade, amplifying the global cumulative excitation energy by nearly 75%. Notably, the dominant high-frequency excitation consistently converges within a narrow band of 760 Hz to 790 Hz, independent of flow rate variations. These findings provide a theoretical foundation for unsteady excitation source localization and targeted vibration reduction in complex industrial pipeline networks. Full article

Flexible pressure sensors serve as core sensing components for wearable health monitoring systems, electronic skins for soft robots, and flexible human–machine interaction devices. Benefiting from the interfacial electric double-layer polarization effect, iontronic sensing delivers far higher pressure response sensitivity than conventional parallel-plate capacitive sensors, endowing it with distinctive advantages in the detection of weak physiological signals. Nevertheless, current dense ionic thin-film dielectric layers suffer from limited deformation space under compression and poor low-pressure sensing capability. Mainstream high-precision micropillar arrays are fabricated via photolithography, 3D printing, and metal etching molds, which require costly equipment and complicated fabrication procedures, making large-area mass production unfeasible. Random frosted concave-convex microstructures feature disordered dimensions, leading to severe device hysteresis and narrow linear ranges, which fail to achieve ultrahigh sensitivity alongside a wide pressure detection range simultaneously. To address the aforementioned multiple bottlenecks, this paper proposes a low-cost resin template replication process to fabricate TPU-based ionic thin-film dielectric layers with ordered micropillar array microstructures. Combined with inkjet-printed silver conductive PI flexible electrodes, an iontronic flexible pressure sensor with a sandwich layered structure is constructed. Multi-dimensional investigations including microscopic morphology characterization, electromechanical sensing performance calibration, and human wearable application tests are systematically implemented to thoroughly elucidate the synergistic enhancement mechanism of the arrayed micropillars. Test results demonstrate that the effective pressure detection range of the sensor spans 0–1038 kPa, accommodating ultra-low pressures such as pulse signals as well as medium-to-high-pressure loads including joint bending. The sensitivity reaches 23.27 kPa⁻¹ within the low-pressure range of 0–200 kPa and remains stable at 3.52 kPa⁻¹ in the high-pressure range of 200–1038 kPa, with piecewise linear fitting correlation coefficients of 0.93 and 0.96 respectively. Both the response time and recovery time of the device are 40 ms, and the hysteresis error throughout the loading-unloading cycle is merely 2.62%. After 20,000 consecutive cyclic loading-unloading tests, the peak capacitance output only decays by 5.1%, verifying outstanding mechanical fatigue resistance and electrical stability. Validations in multi-scenario applications prove that the sensor can accurately capture human physiological and motion signals including radial artery pulses, laryngeal deformation induced by multi-syllable vocalization, and multi-angle bending of fingers and elbow joints, suitable for home-based health monitoring, quantitative rehabilitation training, flexible tactile interaction and other scenarios. The entire fabrication process eliminates high-precision micro-nano processing equipment such as photolithography systems, plasma etchers and 3D printers; only general chemical raw materials and conventional laboratory instruments are adopted. The reusable templates enable low manufacturing costs and large-area coating forming, offering a novel low-cost technical solution for the engineering implementation and industrialization of high-performance iontronic flexible pressure sensors. Full article

Underground coal mining faces coupled hazards from respirable coal dust and spontaneous coal combustion. This study developed a dual-function flame-retardant dust suppressant comprising carboxymethyl cellulose (CMC), polycarbodiimide (PCDI), ammonium polyphosphate (APP), and zinc borate (ZB). A four-factor, three-level orthogonal design was used to screen formulations by penetration depth, followed by rheological, water-scour, simulated-roadway, temperature-programmed oxidation, contact-angle, Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscope (SEM) analyses. CMC and PCDI significantly affected penetration, whereas APP and ZB showed no significant effects within the tested ranges. The selected formulation (1% CMC, 12% APP, 3.5% ZB, and 1.5% PCDI) showed stable viscosity development and the lowest mass loss under repeated water scour. In simulated-roadway tests, the stock solution achieved an average dust-suppression efficiency of 59.7%. At 170 °C, a 10% treatment reduced CO release by 40.0% and increased the mean apparent activation energy of coal oxidation by 29.73%. Rapid wetting, intermolecular interactions, and formation of a continuous porous crosslinked film supported dust consolidation and oxidation inhibition. The developed material therefore offers a potential integrated approach for controlling coal dust and spontaneous combustion risks in underground mines. Full article

Quantum tunneling is conventionally described by the Schrödinger wave equation with a prescribed static potential barrier, providing accurate transmission probabilities but offering limited insight into the microscopic dynamics of particle–barrier interactions. In this work, we develop a dynamical second-quantization framework in which the barrier is modeled as an ensemble of quantized internal modes rather than as an externally imposed classical potential. The tunneling particle interacts directly with these microscopic barrier excitations through a coupled particle–barrier Hamiltonian, from which the Heisenberg equations of motion are derived. Collective coherent excitations of the barrier modes give rise to an emergent effective barrier that naturally recovers the conventional rectangular barrier and the WKB transmission limit under appropriate conditions. Unlike standard treatments, the present formulation explicitly incorporates microscopic barrier dynamics and provides a unified description of particle–barrier coupling within a second-quantized formalism. The framework further suggests that repeated tunneling events may experience different microscopic interaction histories, motivating a statistical interpretation of tunneling times. Because both the particle and barrier are treated within the same operator formalism, the theory provides a natural foundation for extension to relativistic quantum transport, photonic barriers, cavity quantum electrodynamics, and other structured quantum media. Full article