Search Results (7,189)

To improve the accuracy of second-order cell-centered finite volume method in near-boundary regions for solving the two-dimensional shallow water equations, a numerical scheme with globally second-order accuracy was proposed. Having the primary objective to overcome the challenge of accuracy degradation in near-boundary regions and to develop a robust numerical framework combining high-order accuracy with strict conservation, the key research objectives had been as follows: Firstly, a physical variable reconstruction method combining a vertex-based nonlinear weighted reconstruction scheme and a monotonic upwind total variation diminishing scheme for conservation laws was proposed. While the overall computational efficiency was maintained, linear-exact reconstruction in near-boundary regions was achieved. The variable reconstruction in interior regions was integrated to achieve global second-order accuracy. Subsequently, a flux boundary condition treatment method based on uniform flow was proposed. Conservative allocation of hydraulic parameters was achieved, and flow stability in inflow regions was enhanced. Finally, a series of numerical test cases were provided to validate the performance of the proposed method in solving the shallow water equations in terms of high-order accuracy, exact conservation properties, and shock-capturing capabilities. The superiority of the method was further demonstrated under high-speed flow conditions. The high-precision numerical model developed in this study holds significant value for enhancing the predictive capability of simulations for natural disasters such as flood propagation and tsunami warning. Its robust boundary treatment methods also provide a reliable tool for simulating free-surface flows in complex environments, offering broad prospects for engineering applications. Full article

The photocatalytic activity of Bi₂WO₆ Aurivillius phase has been widely exploited for the degradation of a wide range of gaseous and aqueous molecules, as well as microorganisms, under the influence of visible irradiation. Strategies for the development of doped and co-doped bismuth tungstate materials require the thermodynamic data on this phase. The heat capacity of bismuth tungstate, Bi₂WO₆, was investigated using a DSC microcalorimeter on polycrystalline powder samples in the temperature range from 313 to 1103 K (40–830 °C) in two separate runs. The samples were synthesized by solid-state reaction from pure binary oxides at 1033 K (760 °C) in a platinum crucible with cover. The high temperature C_p(T) data were fitted by the Maier–Kelley equation and, from this relation, the standard molar heat capacity of γ-Bi₂WO₆ polymorph was estimated to be at 298.15 K 176.8 ± 3.9 J·K⁻¹·mol⁻¹. A reversible second-order transition of Bi₂WO₆ phase was observed in the experimental temperature range, with a peak close to 940 K (667 °C). Additionally, the extrapolation of C_p(T) to 0 K was proposed using a method based on the multiple Einstein model. Thermodynamic properties (heat capacity C_p(T), entropy S°(T), enthalpy H°(T), Gibbs energy G°(T)) of crystalline γ-Bi₂WO₆ were calculated in the temperature range of 298.15–1123 K (25–850 °C). Full article

The Hertz equation is the most widely used equation for data processing in AFM nanoindentation experiments on soft samples when using spherical indenters. Although valid only for small indentation depths relative to the tip radius, it is usually preferred because it directly relates applied force to indentation depth. Sneddon derived accurate equations relating force and contact radius to indentation depth for shallow and deep indentations, but they are rarely used in practice. This paper presents analytical approaches to solving Sneddon’s nonlinear system. Using Taylor series expansions and a simple equation linking applied force, average contact radius, and indentation depth, we derive a two-term equation that directly relates force to indentation depth. This expression is accurate for h ≤ 1.5 R, where h is the indentation depth and R is the indenter radius, making it applicable to most practical AFM measurements on soft materials. It should be used instead of the Hertzian model for extracting Young’s modulus, thereby enhancing measurement accuracy without increasing the complexity of data processing. In addition, the results are generalized to produce a series solution that is valid for large indentation depths. The newly derived equations proposed in this paper are tested on both simulated and experimental data from cells, demonstrating excellent accuracy. Full article

Fractional-order predator–prey models provide superior ecological fidelity by capturing intrinsic memory effects. However, the fractional derivative order introduces an additional dimension to parameter space, which is unexplored in existing dynamical analyses. This paper delves into the bifurcation behaviors of a two-dimensional fractional-order predator–prey model, taking into account the maturation period of larvae. By utilizing time delay as the bifurcation parameter, the characteristic equation is analyzed to derive conditions for stability and bifurcation. Meanwhile, the introduction to fractional-order theory endows the predator–prey system with improved historical dependence. The relationship between order and bifurcation behavior in the fractional-order predator–prey model is discussed in simulation experiments, which provides a reference for the establishment of the fractional-order system. Additionally, this paper introduces a controller to control the bifurcation behavior through feedback-gain parameters. Simulation results not only exhibit the dynamic characteristics of fractional-order models, but also demonstrate the success of controllers over bifurcation behaviors. Full article

Sustainable soil management requires striking a balance between productivity and soil health. While agroforestry practices are known to improve soil health and ecosystem functions, the contribution of microbial diversity to maintaining multifunctional soil processes in pecan (Carya illinoinensis) cultivation has yet to be fully elucidated. This study examined microbial diversity, soil functions, and multifunctionality across different pecan intercropping setups. We compared a monoculture pecan plantation with three agroforestry models: pecan–Paeonia suffruticosa–Hemerocallis citrina (CPH), pecan–P. suffruticosa (CPS), and pecan–P. lactiflora (CPL). We employed high-throughput sequencing (16S and ITS) to determine the soil bacterial and fungal communities and analyzed the species diversity, extracellular enzyme activities, and physicochemical properties. Soil multifunctionality (SMF) was evaluated using 20 indicators for nutrient supply, storage, cycling, and environmental regulation. Agroforestry increased soil fungal diversity and improved multifunctionality when compared to monoculture. The CPS and CPH models were the most beneficial, increasing multifunctionality by 0.74 and 0.55 units, respectively. Structural equation modeling revealed two key pathways: bacterial diversity significantly enhanced nutrient cycling and environmental regulation, whereas fungal diversity primarily promoted nutrient cycling. These pathways together delivered clear gains in multifunctionality. Random forest analysis identified key predictors (total nitrogen, total carbon, available potassium, β-1,4-N-acetylglucosaminidase, and alkaline phosphatase), highlighting the joint importance of nutrients and microbial enzymes. Our results demonstrate that selecting species in pecan agroforestry alters microbial communities and activates key functions that support soil health and long-term resilience. Hence, pecan agroforestry maintains SMF through microbial processes, with CPS showing the strongest effect. These results can inform species selection and encourage broader testing for resilient, biodiversity-based farming practices. Full article

The platelet-to-lymphocyte ratio (PLR) has been used as a marker of inflammation, endothelial damage, and a predictor of mortality. Expanded hemodialysis (HDx) using medium cut-off dialyzer (MCO) can effectively clear medium-sized uremic toxins. This study evaluated the effect of the Theranova dialyzer, a type of MCO dialyzer, on PLR and uremia-related inflammatory markers. A total of 44 patients with maintenance hemodialysis (HD) using high-flux dialyzer were randomly allocated to the Theranova or high-flux group. PLR and inflammatory markers including fibroblast growth factor 23, tumor necrosis factor-α (TNF-α), and interleukin 6 were evaluated every 4 weeks. The changes in PLR and the reduction ratio of inflammatory markers were compared between two groups during the 12-week study period. The baseline characteristics and PLR were not different between groups. After 12 weeks, the levels of PLR, and TNF-α were significantly lower in the Theranova group compared to the high-flux group (all p < 0.05). The generalized estimating equation model also revealed a significant decrease in PLR over time in the Theranova group than in the high-flux group (p = 0.04). The fold change in 12-week PLR to baseline PLR was lower in the Theranova group than in the high-flux group (p = 0.03). In the multivariable linear regression analysis, the Theranova dialyzer showed a negative correlation with the PLR fold change (β = −0.32, p = 0.04). Our results showed that HDx using the Theranova dialyzer improves PLR over time compared to the high-flux HD. The superior removal of the inflammatory uremic toxins by the Theranova dialyzer may have reduced inflammation and inflammation-related complications in HD patients. Full article

We develop and analyze a reaction-diffusion model describing the early spatial dynamics of viral infection in tissue, incorporating key components of the innate immune system: inflammatory cytokines and circulating macrophages. The system couples three spatial partial differential equations (for uninfected cells, infected cells, and virus particles) with two ordinary differential equations (for cytokines and activated macrophages), and it includes time delays related to intracellular viral replication. In the absence of macrophage degradation, we derive analytical expressions for the total viral load and the wave speed, and we identify explicit immune control thresholds in terms of the virus replication number and the strength of the immune response. In the presence of macrophage degradation, simulations reveal that increasing macrophage turnover accelerates wave propagation and increases viral burden. These results highlight the critical role of innate immune feedback, modulated by effector degradation, in shaping the spatial outcome of infection. Depending on the values of viral replication number and the strength of the immune response, infection can be immediately suppressed, or it can propagate with gradual extinction due to the time-dependent immune response, or it can persistently propagate in the tissue in the form of a reaction-diffusion wave. Full article

This study examines how knowledge heterogeneity affects team creativity in the context of China’s digital intelligence transformation and analyzes the mediating effects of digital intelligence enablement and technology management capability. Grounded in the knowledge-based view and dynamic capability theory, a sequential mediation model of the effect of knowledge heterogeneity on team creativity is developed and tested using both hierarchical regression and structural equation modeling. We conducted a two-wave anonymous questionnaire survey in a knowledge-intensive enterprise in Shanghai and obtained 203 valid responses. The results indicate that we draw three main conclusions. First, knowledge heterogeneity has a significant positive effect on team creativity. Second, technology management capability and digital intelligence enablement act as mediators in this relationship. Technology management capability improves the efficiency of transforming heterogeneous knowledge, while digital intelligence enablement facilitates the integration and application of such knowledge. Finally, technology management capability and digital intelligence enablement together form a sequential mediation pathway, where heterogeneous knowledge first enhances technology management capability and then promotes digital intelligence enablement, ultimately fostering team creativity. This study deepens the understanding of how knowledge heterogeneity promotes team creativity and provides implications for advancing digital intelligence transformation and industry competitiveness. Full article

This study investigated the drying–grinding–extrusion processing of camel compound feeds enriched with locally available botanicals. A 2 × 2 × 3 full factorial design was applied to evaluate the effects of infrared drying temperature (two levels), grinding time (two levels), and extrusion screw speed (three levels) on process efficiency and product quality. Moisture calibration was performed using gravimetric reference values. Drying kinetics were modeled with Page and Midilli equations, while specific energy consumption (SEC) and specific moisture extraction rate (SMER) were calculated. Particle-size distribution, extrusion parameters, and extrudate properties (expansion ratio, bulk density, water absorption index (WAI), water solubility index (WSI), hardness, and color) were analyzed. Infrared drying resulted in faster moisture removal and greater energy efficiency compared with convective drying. The Midilli model provided the best fit to drying kinetics data. The results indicate that optimized combinations of drying, grinding, and extrusion conditions can enhance the technological and nutritional potential of camel compound feeds; however, biological validation is required. Limitations: These findings are limited to processing and compositional outcomes; biological validation in camels (in vivo or in vitro) remains necessary to confirm effects on digestibility, health, or performance. Full article

In order to address environmental challenges, higher education is required to promote competencies that support sustainable entrepreneurship. This study analyzes the relationship between green skills and sustainable entrepreneurial intentions among business students in Mexico. A quantitative, cross-sectional, and explanatory design was applied with a sample of 766 students from two higher education institutions in Hidalgo. Data were examined through partial least squares structural equation modeling (PLS-SEM). The results confirm positive and significant relationships between green skills and sustainable entrepreneurial intentions, progressing through four stages: green knowledge, mastery of green skills, use of green skills, and green skill development. The model reveals that 44.50% of green entrepreneurial intention is associated with green skills, indicating that students with stronger green competencies are more likely to pursue sustainable ventures. This study contributes to the literature by addressing a gap in the Latin American context and provides implications for educational institutions and policymakers to strengthen sustainability-oriented entrepreneurship. Full article

In this work, we investigate quantum correlations, including entanglement and quantum discord, within the hyperfine structure of the hydrogen atom using the Lindblad master equation to model its dynamics as an open quantum system interacting with an environment. By incorporating realistic environmental influences, we examine the time evolution of two key measures of quantum correlations: concurrence, which quantifies entanglement, and local quantum uncertainty (LQU), a broader indicator of quantumness. Our analysis spans various initial states, including coherent superpositions of hyperfine states, to capture a wide range of possible configurations and demonstrate how these measures capture distinct aspects of quantum behavior. The results reveal the robustness of LQU in regimes where entanglement may vanish. This resilience of LQU underscores its utility as a robust measure of quantum correlations beyond entanglement alone in the hydrogen atom. By elucidating the dynamics of quantum correlations in the hydrogen atom under realistic conditions, this work not only deepens our fundamental understanding of atomic systems but also highlights their potential relevance to quantum information science and the development of quantum technologies. Full article

This paper presents soliton solutions of the fractional (2+1)-dimensional Davey–Stewartson equation based on a local fractional derivative to represent wave packet propagation in dispersive media under both spatial and temporal effects. The importance of this work is in demonstrating how fractional derivatives represent a more capable modeling tool compared to conventional integer-order methods since they include anomalous dispersion, nonlocal interactions, and memory effects typical in most physical systems in nature. The main objective of this research is to build and examine a broad family of soliton solutions such as bright, dark, singular, bright–dark, and periodic forms, and to explore the influence of fractional orders on their amplitude, width, and dynamical stability. Specific focus is given to the comparison of the behavior of fractional-order solutions with that of traditional integer-order models so as to further the knowledge on fractional calculus and its role in governing nonlinear wave dynamics in fluids, plasmas, and other multifunctional media. Methodologically, this study uses the fractional complex transform together with a new mapping technique, which transforms the fractional Davey–Stewartson equation into solvable nonlinear ordinary differential equations. Such a systematic methodology allows one to derive various families of solitons and form a basis for investigation of nonlinear fractional systems in the general case. Numerical simulations, given in the form of three-dimensional contour maps, density plots, and two-dimensional, demonstrate stability and propagation behavior of the derived solitons. The findings not only affirm the validity of the devised analytic method but also promise possibilities of useful applications in fluid dynamics, plasma physics, and nonlinear optics, where wave structure manipulation using fractional parameters can result in increased performance and novel capabilities. Full article

This study validates the Compassionate Engagement and Action Scales for Self and Others (CEAS) for use with undergraduate engineering students in the United States. Compassion, defined as sensitivity to suffering in oneself and others coupled with a commitment to alleviate and prevent it, is increasingly recognized as a vital socio-emotional competency in professional education. Using a cross-sectional survey design, 434 engineering undergraduates completed the CEAS instrument. In addition, students responded to open-ended questions about their definition of compassion and “others” as well as a validated engineering identity scale. Structural equation modeling supported the hypothesized three-flow, two-component structure of compassion, with excellent fit indices (CFI = 0.980, RMSEA = 0.037) and generally strong factor loadings. Reliability was high for most subscales (α = 0.716–0.762), though self-compassion engagement showed lower internal consistency (α = 0.614). Divergent validity was confirmed through weak correlations with engineering identity dimensions. Qualitative salience and thematic analysis revealed that participants most frequently associated compassion with empathy, kindness, caring, and understanding and defined “others” mainly as friends, family, and classmates, with high-compassion scorers being more compassion oriented and including broader social circles. Findings support the CEAS’s structural validity and utility in engineering education while highlighting opportunities to strengthen self-compassion engagement to enhance well-being, ethical reasoning, and socially responsible practice among future engineers. Full article

Prolonged stress caused by the COVID-19 pandemic and two concurrent earthquakes in 2020 increased Internet-based addictive behaviour, leading to decrease in mental health and quality of life (QoL) in the adult Croatian population. This study examined the association between Internet-based addictive behaviour and QoL during prolonged stress (pandemic and earthquakes). Specifically, it explored direct associations between QoL domains and overall/specific Internet use, problematic Internet use (PIU), and symptoms of anxiety, depression, and stress, as well as the indirect role of these symptoms in mediating the relationship between PIU and QoL. A cross-sectional online survey was conducted in autumn 2021 with a convenience sample (N = 1004; 82.2% women; M age = 34.98, SD = 12.24). Measures included increased overall and specific Internet use, PIU, stress (Impact of Event Scale), anxiety and depression symptoms (Hospital Anxiety and Depression Scale), and QoL (WHOQoL-BREF). Structural equation modelling showed that increased Internet use and PIU were directly associated with more severe symptoms of depression, anxiety, and stress, and with lower QoL. Significant indirect effects were also found: higher PIU, social media use, online shopping, and pornography viewing predicted greater depression, anxiety, and stress symptoms, which in turn predicted reduced QoL across multiple domains. These findings suggest that problematic and increased Internet use during periods associated with prolonged stress contribute to lower QoL through elevated psychological distress. Full article

Electromagnetically induced transparency (EIT) is well known as a quantum optical phenomenon that permits a normally opaque medium to become transparent due to the quantum interference between transition pathways. This work addresses multi-soliton dynamics in an EIT system modeled by the integrable Maxwell–Bloch (MB) equations for a three-level $\Lambda$-type atomic configuration. By employing a generalized gauge transformation, we systematically construct explicit N-soliton solutions from the corresponding Lax pair. Explicit forms of one-, two-, three-, and four-soliton solutions are derived and analyzed. The resulting pulse structures reveal various nonlinear phenomena, such as temporal asymmetry, energy trapping, and soliton interactions. They also highlight coherent propagation, elastic collisions, and partial storage of pulses, which have potential implications for the design of quantum memory, slow light, and photonic data transport in EIT media. In addition, the conservation of fundamental physical quantities, such as the excitation norm and Hamiltonian, is used to provide direct evidence of the integrability and stability of the constructed soliton solutions. Full article