Search Results (551)

The Krabi mouth-brooding fighting fish, Betta simplex Kottelat, 1994, is a critically endangered and endemic fish species in Krabi province, Southern Thailand. Little information is available on its reproductive ecology and early developmental morphology, which are essential for studying its conservation. Generally, B. simplex is considered an adaptable animal that can tolerate lower alkalinity and higher hardness compared to its natural environment conditions. In this study, wild broodstocks of B. simplex were collected from the reported type localities and bred in captivity under laboratory conditions for size-series collection. Some biological aspects of B. simplex in its natural environmental conditions were determined. We found that its flaring and mating behavior was similar to those of bubble-nesting fighting fish but did not involve bubble-nest building. The fertilized eggs and pre-flexion larvae were nurtured in the mouth cavity of parental males within 11–12 (mode = 11) days after fertilization (DAF). The first-release offspring developed to the post-flexion stage with a body size of 4.39 ± 0.01 mm of standard length (SL; n = 6) and then to the juvenile stage within 30 days after release with 11.72 ± 0.62 mm SL (n = 4). Thus, we propose the following linear regression equation for growth prediction by age (DAF) and body size (SL; mm): age = 0.2425 SL + 1.7036 (r² = 0.9549). The findings of this study will deepen our knowledge of the reproduction and ontogeny of B. simplex and contribute to its future conservation and management. Full article

This study employs the modified extended direct algebraic method (MEDAM) to investigate the generalized nonlinear fractional $(3+1)$-dimensional wave equation with gas bubbles. This advanced analytical framework is used to construct a comprehensive class of exact wave solutions and explore the associated dynamical characteristics of diverse wave structures. The analysis yields several categories of soliton solutions, including rational, hyperbolic (sech, tanh), and trigonometric (sec, tan) function forms. To the best of our knowledge, these soliton solutions have not been previously documented in the existing literature. By selecting appropriate standards for the permitted constraints, the qualitative behaviors of the derived solutions are illustrated using polar, contour, and two- and three-dimensional surface graphs. Furthermore, a stability analysis is performed on the obtained soliton solutions to ascertain their robustness and dynamical stability. The suggested analytical approach not only deepens the theoretical understanding of nonlinear wave phenomena but also demonstrates substantial applicability in various fields of applied sciences, particularly in engineering systems, mathematical physics, and fluid mechanics, including complex gas–liquid interactions. Full article

Smoothed particle hydrodynamics (SPHs) is a Lagrangian meshless method with distinct strengths in managing unstable and complex interface behaviors. This study develops an integrated multiphase SPH framework by merging multiple algorithms and techniques to enhance stability and accuracy. The multiphase model is validated by several benchmark examples, including square droplet deformation, single bubble rising, and two bubbles rising. The selection of numerical parameters for multiphase simulations is also discussed. The validated model is then applied to simulate oil–water–gas bubbly flows. Interface behaviors, such as coalescence, fragmentation, deformation, etc., are reproduced, which helps to take into account multiphysics interactions in industrial processes. The rising processes of many oil droplets for oil–water separation are first simulated, showing the advantages and stability of the SPH model in dealing with complex interface behaviors. To fully explore the potential of the model, the model is further extended to the field of wax removal. The melting process of the wax layer due to heat conduction is simulated by coupling the thermodynamic model and the phase change model. Interesting behaviors such as wax layer cracking, droplet detachment, and thermally driven flow instabilities are captured, providing insights into wax deposition mitigation strategies. This study provides an effective numerical model for bubbly flows in petroleum engineering and lays a research foundation for extending the application of the SPH method in other engineering fields, such as multiphase reactor design and environmental fluid dynamics. Full article

This study conducts a bibliometric review of Bitcoin research in the Business and Economics domains, using VOSviewer to visualize network structures and Bidirectional Encoder Representations from Transformers Topic (BERTopic) to derive semantically coherent topic clusters. The analysis identifies five major research themes: (1) Diversification, hedging, and safe-haven properties; (2) Market dynamics, efficiency, and investor behavior; (3) Bitcoin price and volatility prediction attempts; (4) Environmental impact of Bitcoin; and (5) Financial impact of Central Bank Digital Currency (CBDC). Based on these themes, the study recommends further investigation into the influence of Exchange-Traded Fund (ETF) approvals, regulatory frameworks, and institutional investor participation on Bitcoin’s safe-haven potential; the role of market dynamics and regulatory interventions; early detection of herding behavior and price bubbles; the integration of machine learning and deep-learning models for price prediction; the environmental costs associated with mining; and the evolving regulatory and implementation challenges of CBDCs. Overall, this review synthesizes existing scholarship and outlines future research directions for the rapidly evolving cryptocurrency ecosystem. Full article

Every year, up to 40% of the crops in the world are lost to pests. Plants have suffered from prolonged biotic stresses and abiotic stresses, which cause significant changes in complex crop ecosystems, necessitating intensive pest management strategies that have often been accompanied by the struggle against plant pests. Plant pests and diseases control methods heavily reliant on chemical pesticides have caused many adverse effects. One innovative method involves using ultrafine bubble (UFB) waters, which can enable pesticide reduction action for the plant pest control. The classification and six properties of UFBs were summarized, and the generation approaches of UFBs were introduced based on physical and chemical methods. The applications of UFBs and ozone UFB waters in plant protection practices were comprehensively reviewed, in which UFB waters against the plant pests and the soilborne, airborne and waterborne diseases were analyzed, and the abiotic stresses of crops in high-salinity soil and contaminated soil, drought, and soil with heavy metals were reviewed. Despite promising applications, UFB technology has limitations. Aiming at pesticide reduction and replacement using UFB waters, the mechanism of UFB water controlling plant pests and diseases, the molecular mechanism of UFB water affecting plant pest resistance, the plant growth in harsh polluted environments, the UFB behavior with hydrophobic and hydrophilic surfaces of crops, and the building of an integrated intelligent crop growth system were proposed. Full article

Neuronal firing behaviors are fundamental to brain information processing, and their abnormalities are closely associated with neurological disorders. This study conducts a comprehensive bifurcation and firing-behavior analysis of an improved Tabu Learning neuron model using a semi-analytical discrete implicit mapping framework. First, a discrete implicit mapping is constructed for the Tabu Learning neuron, enabling high-precision localization of stable and unstable periodic orbits within chaotic regimes and overcoming the limitations of conventional time-domain integration. Second, an eigenvalue-centered analysis is used to classify bifurcation types and stability, summarized in explicit bifurcation tables that reveal self-similar offset bifurcation routes, coexisting periodic and chaotic attractors, and chaotic bubbling firing patterns. Third, the proposed neuron model and its discrete mapping are implemented on an FPGA platform, where hardware experiments faithfully reproduce the analytically predicted stable and unstable motions, thereby tightly linking theoretical analysis and digital neuromorphic hardware. Overall, this work establishes a unified analytical–numerical–hardware framework for exploring complex neuronal dynamics and provides a potential basis for neuromodulation strategies and neuromorphic computing system design. Full article

The risk of environmental accumulation of aluminum ash and red mud is increasing, emphasizing the demand for high-value utilization. In this study, the conversion of aluminum ash and red mud into porous refractory materials with good thermal insulation performance is successfully demonstrated, demonstrating that both residues can be recovered as a resource and their environmental impact can be reduced in a sustainable manner. The phase composition and microstructure of the waste are evaluated by XRD and SEM/EDS, respectively, while their high-temperature behavior and performance were assessed through visual high-temperature furnace testing. The influence of the aluminum ash-red mud ratio on the rheological behavior of slurries containing surfactants at a constant alkaline pH was highlighted. A slurry composition of 40% red mud and 30% aluminum ash exhibited the lowest shear stress and viscosity values, required to facilitate bubble growth. Building on this formulation, foaming with 2% (mass fraction) H₂O₂ at 80 °C and sintering at 1250 °C produces a material with the optimum performance: a compressive strength of 1.03 MPa, a porosity of 58.55%, and thermal conductivity of 0.19 W/(m·K). The material exhibits long-lasting stability at temperatures ≤ 1100 °C. Thus, complementary compositions of aluminum ash and red mud show potential for practical application and value addition in the preparation of porous refractory materials with thermal insulation properties. Full article

Direct methanol fuel cells (DMFCs) offer advantages such as high energy density and ease of storage and transportation. However, carbon dioxide bubbles generated in the anode flow channels are one factor affecting cell performance. To investigate the multi-bubble coalescence phenomenon of CO₂ bubbles in DMFC flow channels, a three-dimensional anode channel dual-pore model of DMFC is established using the software COMSOL Multiphysics. Through numerical simulation, a systematic study is conducted on the kinetic mechanisms governing the growth, detachment, and coalescence behavior of CO₂ bubbles in the DMFC anode flow channel. The study reveals that bubbles readily coalesce to form large-scale plug flow with low-methanol velocity, whereas high-flow velocity inhibits coalescence and promotes rapid bubble discharge. Pore size significantly influences the aggregation and detachment of CO₂ bubbles, due to the increase in surface tension with the increasing pore diameter, which prevents bubbles from detaching and makes neighboring bubbles more prone to coalescence. Pore spacing directly influences the frequency and intensity of aggregation behavior; increasing pore spacing helps suppress bubble aggregation. The contact angle indirectly affects bubble coalescence and distribution uniformity by regulating bubble detachment rates, and hydrophilic wall surfaces inhibit bubble coalescence. Full article

The pursuit of higher current densities and device miniaturization intensifies gas evolution in alkaline water electrolysis, thereby reducing catalyst utilization and degrading system performance. In this work, a visualized alkaline electrolysis system was developed to investigate bubble dynamics on vertically oriented nickel wire electrodes. High-speed imaging coupled with a Yolov8 deep learning model enabled quantitative analysis of oxygen evolution behavior, revealing distinct bubble evolution modes such as isolated growth and coalescence. Systematic experiments demonstrated that current density, electrode diameter, and KOH concentration exert significant influences on bubble size distribution. Further correlation with electrochemical performance showed that increases in bubble population and size result in higher overpotentials, while bubble volume exhibits a strong linear relationship with the system’s ohmic resistance. These findings provide mechanistic insights into the coupling between bubble evolution and electrochemical performance, offering guidance for the design of efficient alkaline electrolyzers. Full article

This study investigates speculative bubbles in U.S. state-level electricity markets across commercial, industrial, and residential segments. Using monthly data (2005–2025) from the U.S. Energy Information Administration and employing the Generalized Supremum Augmented Dickey–Fuller test, evidence of localized explosive price behavior was observed predominantly in Florida, Hawaii, Pennsylvania, and Oregon, among others. These bubbles, often tied to market disruptions such as fuel price volatility and post-pandemic recovery, were mainly short-lived and region-specific. The findings highlight the need for tailored, state-specific regulatory strategies to address unique market dynamics, ensuring stability amidst the ongoing energy transition. Full article

We perform a molecular dynamics simulation of a bulk eight-component hydrocarbon mixture that roughly represents a composition of hydrocarbon fluid in a volatile oil reservoir. For that goal, we have developed a method for building molecular models of hydrocarbon mixtures which can include various branched molecules. We have used self-periodical simulation boxes with different aspect ratios. Our main focus here is the phase behavior of a multicomponent mixture in the presence of gas–liquid interfaces of different shapes: spherical, cylindrical, and slab-like gas bubbles. We have developed a method for calculating properties of coexisting phases in molecular simulations of multicomponent systems. In particular, it allows us to analyze the local composition of the mixture and to calculate the molar densities of components in liquid and gas phases, and inside the interface layer between them. For the values of model parameters that we have used so far, the mixture is homogeneous at a high pressure and undergoes liquid–gas phase separation upon decreasing the pressure. We have kept the same temperature $T=375.15 \mathrm{K}$, the same composition and the same number of molecules in all systems and used several combinations of the simulation box size and shape to control the overall density, and therefore also the pressure, as well as the presence or absence of a liquid–gas interface and its shape. The gas bubble that appears in the system is mainly composed of methane. There is also a small number of ethane and butane molecules, a tiny number of hexane molecules, and no molecules of heavier components at all. In the liquid phase, all components are present. We also show that inside the gas–liquid interface layer, which is actually quite broad, the molar density of methane is also higher than that of other components and even reaches a maximum value in the middle of the interface. Ethane behaves similarly: its molar density also reaches a maximum inside the interface. The molar density of heavier components grows monotonically from the inner part of the interface towards its outer part and shows a very small (almost not visible) maximum at the outer side of the bubble. Full article

We present a novel formulation of the Rayleigh–Plesset equation to describe stable gas bubble dynamics in viscoelastic media, using bubble volume variation, rather than radius, as the primary variable of the resulting nonlinear ordinary differential equation. This formulation incorporates the linear Kelvin–Voigt model as the constitutive relation for the surrounding fluid, capturing both viscous and elastic contributions, to track the oscillations of a gas bubble subjected to an ultrasonic field over time. The proposed model is solved numerically, subjected to a convergence analysis, and validated by comparisons with theoretical and experimental results from the literature. We systematically investigate the nonlinear oscillations of a single spherical gas bubble in various viscoelastic environments, each modeled with varying levels of rheological complexity. The influence of medium properties, specifically shear elasticity and viscosity, is examined in detail across both linear and nonlinear regimes. This work improves our understanding of stable cavitation dynamics by emphasizing key differences from Newtonian fluid behavior, resonance frequency, phase shifts, and oscillation damping. Elasticity has a pronounced effect in low-viscosity media, whereas viscosity emerges as the dominant factor modulating the amplitude of oscillations in both the linear and nonlinear regimes. The model equation developed here provides a robust tool for analyzing how viscoelastic properties affect bubble dynamics, contributing to improved the prediction and control of stable cavitation phenomena in complex media. Full article

Background: Accurately detecting the onset of saturated boiling in herbal medicine extraction processes is critical for improving production efficiency and reducing energy consumption. However, the traditional monitoring methods based on temperature suffer from time delays. To address the challenge, acoustic emission (AE) signals were used in this study owing to its sensitivity to bubble behavior. Methods: An AE signal acquisition system was constructed for herbal extraction monitoring. Characteristics of AE signals at different boiling stages were analyzed in pure water systems with and without herbs. The performance of AE-based and temperature-based recognition of boiling stages was compared. To enhance applicability in different herb extraction systems, multivariate statistical analysis was adopted to compress spectral–frequency information into Hotelling’s T² and SPE statistics. For real-time monitoring, a self-adaptive decision-making boiling judgment method (BoilStart) was proposed. To evaluate the robustness, the performance of BoilStart under different conditions was investigated, including extraction system mass and heating medium temperature. Furthermore, BoilStart was applied to a lab-scale extraction process of Dabuyin Wan, which is a practical formulation, to assess its performance in energy conservation and efficiency improvement. Results: AE signal in the 75–100 kHz frequency band could reflect the boiling states of herbal medicine extraction. It was more sensitive to the onset of saturated boiling than the temperature signal. Compared with SPE, Hotelling’s T² was identified as the optimal indicator with higher accuracy. BoilStart could adaptively monitor saturated boiling across diverse herbal systems. The absolute error of BoilStart’s boiling determination ranged from 1.5 min to 2.0 min. The increasing-temperature time was reduced by about 22–36%. For the extraction process of Dabuyin Wan, after adopting BoilStart, the increasing-temperature time was reduced by about 29%, and the corresponding energy consumption was lowered by about 26%. Conclusions: The first AE-based method for precise boiling state detection in herbal extraction was established. BoilStart’s model-free adaptability met industrial demands for multi-herb compatibility. This offered a practical solution to shorten ineffective heating phases and reduce energy consumption. Full article

Current cavitating water jet technology for mineral liberation predominantly relies on the micro-jet impact generated by bubble collapse. Consequently, conventional nozzle designs often overlook the shear effects on mineral particles within the internal flow path. Moreover, the cavitation cloud evolution mechanisms in nozzles operating on this innovative principle remain insufficiently explored. This study systematically evaluates the cavitation performance of an innovatively designed cavitating jet nozzle with friction-shear effects (CJN-FSE), whose optimized internal structure enhances the interlayer shear and stripping effects crucial for the liberation of layered minerals. Utilizing high-speed imaging, we visualized submerged friction-shear cavitating water jets and systematically investigated the dynamic evolution patterns of cavitation clouds under jet pressures ranging from 15 to 35 MPa. The results demonstrate that the nozzle achieves effective cavitation, with jet pressure exerting a significant influence on the morphology and evolution of the cavitation clouds. As the jet pressure increased from 15 to 35 MPa, the cloud length, width, and average shedding distance increased by 37.05%, 45.79%, and 211.25%, respectively. The mean box-counting dimension of the cloud contour rose from 1.029 to 1.074, while the shedding frequency decreased from 1360 to 640 Hz. Within the 15–25 MPa range, the clouds showed periodic evolution, with each cycle comprising four stages: inception, development, shedding, and collapse. At 30 MPa, mutual interference between adjacent clouds emerged, leading to unsteady shedding behavior. This study thereby reveals the influence of jet pressure on the dynamic evolution patterns and unsteady shedding mechanisms of the clouds. It provides a theoretical and experimental basis for subsequent research into the nozzle’s application in liberating layered minerals and proposes a new design paradigm for cavitation nozzles tailored to the mechanical properties of specific minerals. Full article

It is difficult to collect fine graphite particles because of the large size and small specific area of traditional flotation bubbles. The contrast experiment between nanobubble flotation and traditional flotation of micro-fine flake graphite in the Hegang area of Heilongjiang Province was carried out in this paper. Under the conditions of feed fineness 78% (−74 μm), pH 10.5, sodium hexametaphosphate 800 g/t, No. 2 oil 350 g/t, pulp concentration 10%, diesel 400 g/t, and pulp cycle time 3 min, the enhanced behavior of nanobubbles on micro-flake graphite flotation was discussed by studying the differences in the flotation rate, selectivity, pulp size, and concentrate size between traditional flotation and nanobubble flotation. The results showed that the nanobubble flotation completed the flotation 20 s earlier than the traditional flotation, and the final concentrate recovery of nanobubble flotation was 1.5 percentage points higher than the traditional flotation. In addition, the average particle size of the slurry from nanobubble flotation is 13 μm larger than that from traditional flotation. In addition, the minimum size of nanobubble flotation is only 2 μm, 11 μm smaller than the minimum size of traditional flotation. Nanobubbles effectively reduce the electrostatic repulsion between fine particles and enhance the hydrophobic attraction, making the hydrophobic aggregates of fine particle graphite more stable. At the same time, the presence of nanobubbles makes the surface hydrophobicity of graphite stronger, effectively promoting the recovery of fine particle graphite. Full article