Search Results (7,463)

Advancements in tumor immunology and immunotherapy demonstrate that the immune system plays a crucial role in protecting the body against tumors and may be utilized to prevent or treat them. To investigate this further, we propose a mathematical model to study the complex dynamics of tumor–immune interactions under combined treatment: immunotherapy and chemotherapy. The proposed model consists of six coupled nonlinear ordinary differential equations (ODEs) describing the interaction of tumor cells with specific immune system components (immunostimulatory and immunosuppressive intermediates) and the effects of chemotherapy and immunotherapy. The antigen-presenting cells (APCs), specifically dendritic cells, are incorporated as the immunotherapy. We examine the essential characteristics of the system’s solutions, including existence, boundedness, and positivity. Furthermore, we investigate the presence and stability of equilibrium in two scenarios: intervention of immunotherapy alone and combined use of chemotherapy and immunotherapy. Each model exhibits two equilibria: a tumor-free equilibrium and a tumorous equilibrium. The stability analysis outlines the dynamic behavior associated with each equilibrium point. Additionally, we performed a sensitivity analysis and numerical simulations to validate our theoretical findings empirically. Using numerical simulations and stability analysis, we investigated the effects of treatments on tumor–immune dynamics. Full article

Background: Persistent liver pathology despite a sustained virologic response (SVR) to hepatitis C virus (HCV) therapy is a major clinical concern. This is particularly relevant for people with HIV (PWH) with HCV coinfection, a population prone to accelerated liver disease progression. This study aimed to characterize the plasma miRNA profile in PWH with cirrhosis one year after successful completion of HCV therapy, and to explore their relationship with metabolite alterations. Methods: This cross-sectional study enrolled 47 PWH who achieved HCV clearance with antiviral therapy. Using plasma samples collected approximately one year after completion of HCV therapy, participants were stratified into two groups based on liver stiffness measurement (LSM): compensated cirrhosis (n = 32, LSM ≥ 12.5 kPa) and non-cirrhosis (n = 15, LSM < 12.5 kPa). Plasma miRNAs and metabolites were determined using small RNA sequencing and untargeted capillary electrophoresis-mass spectrometry (CE-MS), respectively. Significantly differentially expressed (SDE) miRNAs were identified using generalized linear models (GLM) with a negative binomial distribution, and their correlation with metabolite levels was quantified using Spearman’s correlation. Results: In the cirrhosis group (n = 32), we identified a distinct signature of 15 SDE miRNAs (9 upregulated, 6 downregulated) compared to the non-cirrhotic group (n = 15), showing hsa-miR-10401-3p, hsa-miR-548ak, hsa-miR-141-3p, and hsa-miR-3940-3p the largest expression changes. miRNA-gene interaction and pathway enrichment analysis suggested that these 15 SDE miRNAs potentially regulate multiple genes involved in immune response and amino acid metabolism. In addition, correlation analyses with our metabolomic data revealed significant associations between specific SDE miRNAs and amino acids and their derivatives. Specifically, the expression of upregulated miRNAs (e.g., hsa-miR-10401-3p and hsa-miR-16-5p) was positively correlated with plasma levels of L-methionine and its derivatives, while downregulated miRNAs (e.g., hsa-miR-625-5p) were inversely correlated with L-tryptophan. Conclusions: In cirrhotic PWH with history of HCV coinfection, a distinct plasma miRNA signature linked to dysregulated amino acid metabolism is found one year after completion of HCV therapy. This underscores that the HCV cure does not equate to complete hepatic recovery, highlighting the critical need for long-term monitoring in this high-risk population. Full article

This study investigates the determinants of turnover intention among real estate sales professionals in Lebanon and the United Arab Emirates (UAE), two markets that represent contrasting economic realities within the MENA region. Drawing on Herzberg’s Two-Factor Theory, Vroom’s Expectancy Theory, and March and Simon’s Push-Pull Model, this study adopts a multidimensional framework to assess the effects of compensation, job stress, career growth opportunities, and work–life balance on employee retention. A quantitative method was employed using a structured questionnaire administered to 832 respondents (425 in the UAE and 407 in Lebanon), and data were analyzed using Structural Equation Modeling. The results reveal that job stress is the most influential predictor of turnover intention, particularly in Lebanon, followed by work–life balance, compensation, and career growth opportunities. These findings underscore the importance of psychological well-being and structural incentives in talent retention. By offering empirical evidence from an underexplored regional labor market, the study contributes to the global turnover discourse and provides comparative insights into the labor dynamics of both a crisis-prone and a high-growth economy. The results carry significant practical implications for HR managers, firm owners, and policymakers, highlighting the necessity of adopting holistic and context-sensitive retention strategies that extend beyond financial rewards to include flexible work arrangements, career development frameworks, and supportive workplace cultures. Full article

The dynamical processes in the atmosphere are coupled with the chemistry of the atmosphere. Internal gravity waves influence the distribution of chemical constituents in the atmosphere through their effects on the background wind or mean flow. We examine a coupled system of equations comprising a nonlinear transport equation of Fisher type for the distribution of the chemical species, along with nonlinear Boussinesq equations for internal gravity waves in a vertically stratified and vertically sheared fluid flow in a two-dimensional region. In our model, a horizontally localized gravity-wave packet is generated and propagates upward into a localized region where the chemical species is present. Numerical solutions show that the wave-induced mean flow resulting from nonlinear gravity-wave interactions in the vicinity of a critical level leads to modifications in the distribution of the chemical. An asymptotic analysis of a related qualitatively similar problem gives us information on the dominant behaviour of the chemical concentration perturbation. We conclude that nonlinearity and vertical shear play a vital role in the interplay between gravity-wave dynamics and chemical distributions in the atmosphere. Full article

Petroleum coke quality strongly influences refinery economics and downstream energy use, yet real-time control is constrained by slow quality assays and a 24–48 h lag in laboratory results. This study introduces a physics-informed combinatorial digital twin for value-optimized coking, aimed at improving energy efficiency and environmental performance through adaptive quality forecasting. The approach builds a modular library of 32 candidate equations grouped into eight quality parameters and links them via cross-parameter dependencies. A two-level optimization scheme is applied: a genetic algorithm selects the best model combination, while a secondary loop tunes parameters under a multi-objective fitness function balancing accuracy, interpretability, and computational cost. Validation on five clustered operating regimes (industrial patterns augmented with noise-perturbed synthetic data) shows that optimal model ensembles outperform single best models, achieving typical cluster errors of ~7–13% NMAE. The developed digital twin framework enables accurate prediction of coke quality parameters that are critical for its energy applications, such as volatile matter and sulfur content, which serve as direct proxies for estimating the net calorific value and environmental footprint of coke as a fuel. Full article

The competitive adsorption of two model herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-chloro-2-methylphenoxyacetic acid (MCPA), onto Activated Carbons (ACs) derived from pomegranate peels through chemical activation with phosphoric acid (H₃PO₄) was investigated in fixed-bed column mode. The prepared activated carbon (AC-PA) exhibited a high apparent surface area (up to 1409 m²/g) and a predominantly microporous structure. Morphological and chemical analyses (micrographic observation, X-ray difraction, N₂ adsorption–desorption) confirmed the presence of well-developed pore networks and surface oxygenated functionalities. Column adsorption experiments were performed under varying flow rates (0.25–3 mL/min) for both single and binary solutions. The breakthrough data were modeled using the Thomas and Yoon–Nelson equations, achieving high determination coefficients (R² = 0.91–0.99). Lower flow rates favored higher adsorption capacities, reaching 193.61 mg/g for 2,4-D at 0.25 mL/min. Under similar conditions (flow rate of 1.5 mL min⁻¹), the AC provided a better adsorption for 2,4-D than for MCPA in single systems, which was attributed to stronger affinity based on its greater hydrophobicity and prominence to dispersive interactions. In binary systems, competitive effects shifted the results and a noticeable roll-up phenomenon was observed for 2,4-D, attributed to its displacement by MCPA along the bed; this made the adsorbent more effective for MCPA in binary mixtures than in single ones. These findings highlight the potential of pomegranate-based activated carbon as a cost-effective and sustainable adsorbent for herbicide removal in continuous water treatment systems. Full article

Loess subgrades are prone to significant strength reduction and deformation under cyclic traffic loads and moisture ingress. Permeable polyurethane polymer grouting has emerged as a promising non-excavation technique for rapid subgrade reinforcement. This study systematically investigated the fatigue behavior of polymer-grouted loess using laboratory fatigue tests and numerical simulations. A series of stress-controlled cyclic tests were conducted on grouted loess specimens under varying moisture contents and stress levels, revealing that fatigue life decreased with increasing moisture and stress levels, with a maximum life of 200,000 cycles achieved under optimal conditions. The failure process was categorized into three distinct stages, culminating in a “multiple-crack” mode, indicating improved stress distribution and ductility. Statistical analysis confirmed that fatigue life followed a two-parameter Weibull distribution, enabling the development of a probabilistic fatigue life prediction model. Furthermore, a 3D finite element model of the road structure was established in Abaqus and integrated with Fe-safe for fatigue life assessment. The results demonstrated that polymer grouting reduced subgrade stress by nearly one order of magnitude and increased fatigue life by approximately tenfold. The consistency between the simulation outcomes and experimentally derived fatigue equations underscores the reliability of the proposed numerical approach. This research provides a theoretical and practical foundation for the fatigue-resistant design and maintenance of loess subgrades reinforced with permeable polyurethane polymer grouting, contributing to the development of sustainable infrastructure in loess-rich regions. Full article

In today’s increasingly serious environmental problems, a growing number of enterprises are upgrading remanufacturing as an important corporate strategy. This paper compares two third-party remanufacturing models: the entrusting and Authorizing Models, and introduces two different levels of consumer low-carbon preferences: medium and high. By establishing game equations, we find the equilibrium solution of each model. The results reveal that in the basic model, OEM tends to choose the Authorizing Model when consumers have a pronounced quality bias against remanufactured products. Contrary to intuition, TRM always prefers the Entrusting Model. In scenarios where consumers possess medium low-carbon preferences, OEM tends to choose the Authorizing Model when consumers have a high bias against the quality of the remanufactured products or a low bias against the carbon emissions of the new products. Conversely, OEM tends to choose the entrusting remanufacturing model under the opposite conditions. In scenarios where consumers express high low-carbon preferences, the situation becomes the complete opposite. When consumers exhibit a low bias against remanufactured products’ quality or a high bias against carbon emissions from new products, OEM tends to choose the Authorizing Model. Conversely, OEM prefers the Entrusting Model when consumers’ biases differ. In addition, the consumer surplus and social welfare of the Entrusting Model are higher than those of the Authorizing Model, regardless of the research scenario. Full article

In Proton Exchange Membrane Water Electrolysis (PEMWE), the two-phase flow distribution in the anode field significantly affects overall electrolysis performance. Based on visualized experimental data, in this paper, the reaction kinetics equations were theoretically revised, and a three-dimensional, two-phase, non-isothermal, multi-physics coupled model of the electrolysis was developed and experimentally validated. Four different configurations of rectangular turbulence promoters were designed within the anode serpentine flow field and compared with a conventional serpentine flow field (SFF) in terms of their multi-physics distribution characteristics. The results showed that, in the double-row rectangular block serpentine flow field (DRB SFF), the uniformity of liquid water saturation, temperature, and current density improved by 16.6%, 0.49% and 40.8%, respectively. The normal mass transfer coefficient increased by a factor of 6.3, and polarization performance improved by 6.98%. A cross-arranged turbulence promoter structure was further proposed. This design maintains effective turbulence while reducing flow resistance and pressure drop, thereby enhancing mass transfer efficiency and overall electrolysis performance through improved bubble fragmentation. Full article

In this paper, we investigate the running vacuum energy (RVE) model within the framework of $f\left(Q\right)$ gravity ($f\left(Q\right)$-RVE). In this context, the modified Friedmann equation can be used to establish a formal analogy with the structure of the RVE. A key feature is that the vacuum equation of state is no longer fixed but receives a dynamical correction proportional to $\dot{H}$ and $\ddot{H}/H$. We consider two cases of $f\left(Q\right)$-RVE, denoted as Model I (parametrized by $\nu$) and Model II (parametrized by $\nu$ and $\alpha$), corresponding to the first and second derivatives of H, respectively. The models are constrained using recent DESI BAO data in combination with ${\mathrm{Pantheon}}^{+}$, cosmic chronometer (CC), and CMB observations. Our analysis shows a deviation of $\nu$ from zero at a significance level of ∼$1.4\sigma$ for Model I, while in Model II, $\nu$ and $\alpha$ deviate from zero at $0.7\sigma$ and $1.3\sigma$, respectively, relative to $\mathrm{\Lambda }$CDM. Furthermore, the statistical comparison based on the Akaike, Bayesian, and Deviance Information Criteria (AIC, BIC, DIC) indicates that Model I remains competitive with $\mathrm{\Lambda }$CDM, while Model II is penalized due to its higher complexity and the sensitivity associated with the additional parameter $\alpha$. Full article

Numerical simulation of the electrical conductivity of carbon fiber-reinforced asphalt concrete is essential for understanding its electrical behavior, yet research in this area remains limited. This study prepared six groups of Marshall specimens with carbon fiber (CF) contents of 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, and 0.6 wt%. The resistivity and asphalt concrete (AC) impedance spectra were measured to analyze the effect of fiber content on electrical performance. Nyquist diagrams were fitted to establish an equivalent circuit model, and a representative volume element (RVE) finite element model was developed. The Generalized Effective Medium (GEM) equation was employed to fit the resistivity data. The results show that the resistivity exhibits a two-stage characteristic—an abrupt decrease followed by stabilization, with an optimal CF content range of 0.2–0.4 wt%. Among the equivalent circuit parameters, the contact resistance (R₁) and tunneling resistance (R₂) significantly decreased, the growth of interface capacitance (C₁) slowed, the constant phase element Z_Q increased, and the non-monotonic change of volume resistance (R₃) reflected the heterogeneity of the internal void distribution of the material. The finite element numerical solution for resistivity, derived from the GEM equation, aligns well with experimental values, validating the proposed simulation approach. Full article

Carbon capture is pivotal for achieving carbon neutrality; however, its high energy consumption severely limits the operational flexibility of power plants and remains a key challenge. This study, targeting a full flue gas carbon capture scenario for a 1000 MW coal-fired power plant, identified the dual-element (“steam” and “power generation”) coupling convergence mechanism. Based on this mechanism, a comprehensive set of mathematical model equations for the “carbon–electricity–heat” coupling process is established. This model quantifies the dynamic relationship between key operational parameters (such as unit load, capture rate, and thermal consumption level) and system performance metrics (such as power output and specific power penalty). To address the challenge of flexible operation, this paper further proposes two innovative coupled modes: steam thermal storage and chemical solvent storage. Model-based quantitative analysis indicated the following: (1) The power generation impact rate under full THA conditions (25.7%) is lower than that under 30% THA conditions (27.7%), with the specific power penalty for carbon capture decreasing from 420.7 kW·h/tCO₂ to 366.7 kW·h/tCO₂. (2) Thermal consumption levels of the capture system are a critical influencing factor; each 0.1 GJ/tCO₂ increase in thermal consumption leads to an approximate 2.83% rise in unit electricity consumption. (3) Steam thermal storage mode effectively reduces peak-period capture energy consumption, while the chemical solvent storage mode almost fully eliminates the impact on peak power generation and provides optimal deep peak-shaving capability and operational safety. Furthermore, these modeling results provide a basis for decision-making in plant operations. Full article

This study investigates the mechanical characteristics of a multi-stage centrifugal pump rotor through fluid–structure interaction (FSI) analysis. A two-stage centrifugal pump equipped with back vanes on the trailing impeller is selected as the research object. Numerical simulations are performed based on the continuity equation and Reynolds-averaged Navier–Stokes (RANS) equations, with experimental data utilized to validate the numerical model’s accuracy. The internal flow field mechanisms are analyzed, and the effectiveness of two axial force calculation methods—formula-based and numerical simulation-based—for the rotor system is comprehensively evaluated. Employing an FSI-based modal analysis approach, the governing differential equations of motion are established and decoupled via Laplace transformation to introduce modal coordinates. Modal analysis of the pump rotor system is conducted, revealing the first six natural frequencies and corresponding vibration modes, along with critical speed calculations. The findings demonstrate that when the flow field near the back vanes exhibits complex characteristics, the formula-based axial force calculation shows reduced accuracy. In contrast, without back vanes, the hydraulic motion in the impeller rear chamber remains relatively stable, resulting in higher accuracy for formula-based axial force predictions. The calculation error between the two conditions (with/without back vanes) reaches 27.6%. Based on vibration mode characteristics and critical speed analysis, the pump is confirmed to operate within a safe region. The rotor system exhibits two similar adjacent natural frequencies differing by less than 1 Hz, with perpendicular vibration mode directions. Additionally, rotational speed fluctuations in the rotor system induce alternating critical speed phenomena when operating in this region. This study establishes a coupled analysis framework of “flow field stability–axial force calculation accuracy–rotor dynamic response”, quantifies the axial force calculation error patterns under different flow field conditions of a special pump type, supplements the basic data on axial force calculation accuracy for complex structure centrifugal pumps, and provides new theoretical insights and reference benchmarks for the study of hydraulic–mechanical coupling characteristics of similar fluid machinery. In engineering applications, it avoids over-design or under-design of thrust bearings to reduce manufacturing costs and operational risks. The revealed rotor modal characteristics, critical speed distribution, and frequency alternation phenomena can provide direct technical support for the optimization of operating parameters, vibration control, and structural improvement of pump units in industrial scenarios, thereby reducing rotor imbalance, bearing wear, and other failures. Full article

Banana (Musa spp.) fruit morphology is a key determinant of yield and quality, yet modeling its 3D structural dynamics across genotypes remains difficult. To address this challenge, we developed a generic, biomass-driven 3D structural model for banana fruit fingers that quantitatively links growth and morphology. Field experiments were conducted over two growing seasons in Hainan, China, using three representative genotypes. Morphological traits, including outer and inner arc length, circumference, and pedicel length, along with dry (W_d) and fresh weight (W_f), were measured every 10 days after flowering until 110 days. Quantitative relationships between morphological traits and W_f, as well as between W_d and W_f, were fitted using linear or Gompertz functions with genotype-specific parameters. Based on these functions, a parameterized 3D reconstruction method was implemented in Python, combining biomass-driven growth equations, curvature geometry, and cross-sectional interpolation to simulate the fruit’s bending, tapering, and volumetric development. The resulting dynamic 3D models accurately reproduced genotype-specific differences in curvature, length, and shape with average fitting R² > 0.95. The proposed biomass-driven 3D structural model provides a methodological framework for integrating banana fruit morphology into functional–structural plant models. Full article

In this article, we investigate a nonlinear $\psi$-Hilfer fractional order Volterra integro-delay differential equation ($\psi$-Hilfer FRVIDDE) and a nonlinear $\psi$-Hilfer fractional Volterra delay integral equation ($\psi$-Hilfer FRVDIE), both of which incorporate multiple variable time delays. We establish sufficient conditions for the existence of a unique solution and the Ulam–Hyers stability (U-H stability) of both the $\psi$-Hilfer FRVIDDE and $\psi$-the Hilfer FRVDIE through two new main results. The proof technique relies on the Banach contraction mapping principle, properties of the Hilfer operator, and some additional analytical tools. The considered $\psi$-Hilfer FRVIDDE and $\psi$-Hilfer FRVDIE are new fractional mathematical models in the relevant literature. They extend and improve some available related fractional mathematical models from cases without delay to models incorporating multiple variable time delays, and they also provide new contributions to the qualitative theory of fractional delay differential and fractional delay integral equations. We also give two new examples to verify the applicability of main results of the article. Finally, the article presents substantial and novel results with new examples, contributing to the relevant literature. Full article