Search Results (439)

Accurate prediction of biomass pyrolysis products remains challenging due to the inherent complexity of thermochemical kinetics and the lack of mechanistic interpretability in modern Machine Learning (ML) models. This study addresses the black-box problem by comparing a standard Artificial Neural Network (ANN) against a novel Hybrid Physics-Informed Neural Network (PINN) and a Transparent Model (Rough Set ML, RSML) for biochar yield prediction. The standard ANN demonstrated poor generalization performance ($R^2$ = −2.4109) and exhibited physical inconsistency, quantified by a low Physical Consistency Degree ($PCD=0.6429$) and non-monotonic behavior in Partial Dependence Analysis. The PINN was implemented using the Independent Parallel Reactions Scheme (IPRS) to enforce kinetic constraints via a Partial Differential Equation loss ($L_{PDE}$). The results show a critical trade-off: the PINN under standard balancing failed, yielding a PCD value of 0.0714, yet an Extended Kinetic Fitting mode successfully achieved perfect physical coherence ($PCD=1$), demonstrating that enforcing physics acts as a powerful regularizer, leading to a significant improvement in precision ($R^2$ = 0.82). Furthermore, this coherent PINN autonomously discovered a valid Activation Energy ($E_a=150$ kJ/mol), offering direct mechanistic insights by establishing a thermodynamically consistent global activation energy barrier for the primary thermal decomposition stage. This is complemented by the RSML model, which generated highly certain ($cer\ge 95\%$) IF–THEN rules, translating kinetic principles into actionable operational guidelines (e.g., specific thresholds for operating temperature and feedstock Ash content). The study suggests that PIML is a promising pathway for achieving reliable, robust, and mechanistically interpretable modeling in chemical engineering. Full article

The impact of force field models on the thermal and mechanical characteristics of polyimides was comprehensively examined for the first time. Polyimides (PI) are heterocyclic polymers with outstanding thermal and chemical stabilities and excellent dielectric properties. In this study, we used all-atom molecular dynamics (MD) simulations to examine how the flexibility of the dianhydride fragment affects the thermal and mechanical properties of three polyimides: PMDA-ODA, ODPA-ODA, and R-ODA. The considered polyimides have different dianhydride fragments based on pyromellitic acid (PMDA), tetracarboxylic acid diphenyl oxide (ODPA) and 1,3-bis(3′,4-dicarboxyphenoxy)benzene acid (R), with a constant diamine: 4,4′-oxydianiline (ODA). Models were built using five classical force fields (OPLS-AA, Amber/GAFF, Gromos, Charmm/CGenFF, and UFF). For each polyimide, eight models were generated using different force fields and charge schemes: (i) OPLS-AA with 1.14*CM1A charges, (ii) OPLS-AA with HF/6-31G* (RESP) charges, (iii) GAFF with AM1-BCC charges, (iv) GAFF with HF/6-31G* (RESP) charges, (v) CGenFF (version 4.6) with native charges, (vi) CGenFF (version 5.0) with native charges, (vii) Gromos54a7 with native charges, and (viii) UFF with QEq charges. The difference in the chemical structures of the polyimide repeating unit leads to differences in the thermodynamic and kinetic flexibilities that affect the thermal and mechanical properties. Simulations of glass transition temperatures (T_g) for three polyimides PMDA-ODA, ODPA-ODA, and R-ODA mostly replicate the experimental order T_g(PMDA-ODA) > T_g(ODPA-ODA) > T_g(R-ODA), except for the CGenFF (version 4.6) force field. The experimental density ratio ρ(PMDA-ODA) > ρ(ODPA-ODA) > ρ(R-ODA) is most accurately replicated by OPLS-AA (RESP) and CGenFF (version 5.0) polyimide models. The coefficients of thermal expansion (CTE) correspond with the experimental trend, exhibiting an increase in the following order: PMDA-ODA < ODPA-ODA < R-ODA. Gromos54a7 precisely delineates both the ratio and absolute values CTE for all polymers. OPLS-AA (RESP), OPLS-AA (CM1A), CGenFF (version 4.6), and UFF (QEq) models replicate PMDA-ODA’s CTE, while GAFF (RESP) and GAFF (AM1-BCC) models replicate ODPA-ODA and R-ODA CTE values. The ratio between the simulated values of Young’s modulus, yield strength, and strain-hardening modulus followed the sequence PMDA-ODA > ODPA-ODA > R-ODA for the OPLS-AA (RESP) and CGenFF (version 5.0) models. Full article

Low-frequency alternating current (LFAC) transmission has attracted increasing attention for medium- and long-distance offshore wind power transmission, as this application scenario is typically characterized by long transmission distance and large installed capacity. Converting offshore low-frequency alternating current into onshore power-frequency alternating current requires a dedicated frequency conversion device. Compared with power–electronic converter-based schemes represented by the modular multilevel matrix converter (M3C), grid connection via a motor–generator pair (M-G) enables the renewable energy port to retain intrinsic synchronous-machine characteristics, including inertial support, voltage support, and fault isolation. This paper elaborates the operating principles and mathematical models of the two types of frequency conversion solution for LFAC transmission systems, and systematically analyzes the frequency support, voltage support, and fault-isolation capabilities of the M-G scheme. Simulation results demonstrate that under a sudden increase in onshore active power load, the M-G system can provide strong frequency support by releasing rotor kinetic energy, and a larger inertia time constant mitigates the frequency drop more effectively. Under a sudden increase in onshore reactive power load, the M-G scheme offers a greater reactive power margin benefiting from its strong short-term overcurrent capability. Moreover, increasing the excitation gain on the motor side and installing shunt reactors at both ends of the submarine cable can effectively improve the voltage profile along the cable. Full article

A working-state model is proposed for the MnOx–Na₂WO₄/SiO₂ catalyst in oxidative coupling of methane (OCM), where a Na₂WO₄-rich surface environment forms an adaptive interphase that buffers the effective interfacial oxygen chemical potential and stabilizes cooperative MnO_x/Na–WO_x/Mn–O–W motifs. A thermodynamic-kinetic scheme is developed that relates (1) reaction-induced surface enrichment (structural stabilization), (2) oxygen spillover (damping of local oxygen gradients), and (3) Mn ↔ W redox exchange as an electron-oxygen buffer channel. Ex situ XPS/EDS/EPR data indicate a dynamically stratified near-surface region with chemically heterogeneous environments of Mn, W, and O. The W 4f region remains dominated by the W⁶⁺ contribution in the presence of a minor reduced component after OCM. In oxygen-deficient mixtures (CH₄/O₂ > 4), interfacial reconstruction becomes more pronounced: Mn-centered Mars–van Krevelen chemistry determines CH₄ activation and oxygen exchange, while the Na₂WO₄-rich phase ensures fast ion/oxygen transport. Observation of the EPR signal from W⁵⁺ ions in the tungstate matrix indicates the existence of reduced W intermediates at low oxygen potential. Optimization of C₂ selectivity and stability is suggested to require maintaining the catalyst within the selective window of effective interfacial μO by adjusting CH₂/O₂ and contact time, as well as controlling the architecture of the Na–W–O/MnO_x interfacial region. Full article

High-viscosity sodium alginate solutions (4.5% by mass, apparent viscosity 1 × 10⁴–2 × 10⁴ cP) are widely used in the preparation of hydrogels, wet spinning, and biomedical materials. Residual bubbles can cause internal voids in hydrogels, mechanical heterogeneity, fiber breakage during spinning, and reduced strength, and can severely affect the cell compatibility and clinical safety of biomaterials. Due to the difficulty of bubble migration, coalescence, and rupture in high-viscosity systems, traditional vacuum-standing degassing takes up to 24 h and is extremely inefficient, severely limiting the quality of subsequent processing. To address this issue, this study proposes a novel vacuum-assisted centrifugal recirculating degassing method for highly viscous sodium alginate solutions and aims to establish a kinetic framework for describing its overall degassing behavior. Using the number density of bubbles larger than 0.5 mm in diameter as an evaluation metric, we conducted vacuum-standing control experiments and univariate experiments with different screen mesh apertures (5, 1.5, 0.3, and 0.07 mm). We experimentally verified a continuous kinetic model of bubble number decay based on vacuum bubble expansion, centrifugally enhanced migration, and removal probability during the cycle. The results indicate that the bubble removal effect of 40 min of vacuum–centrifugal cyclic degassing is equivalent to that of 4 h of vacuum static settling, representing a 450% increase in degassing efficiency. There is an optimal range for a screen aperture, with the best degassing effect observed at 0.3 mm, achieving a bubble removal rate of 83.69%. The established kinetic model exhibits good fitting accuracy (RMSE = 0.17, MAPE = 5.9%) and can accurately predict degassing efficiency under different process conditions. This study provides a quantifiable, modelable, and optimizable process scheme for rapid degassing of high-viscosity sodium alginate solutions, and offers a theoretical reference for the development of degassing technologies for high-viscosity polysaccharide fluids. Full article

[¹⁸F]-PSMA PET/CT is a high-impact modality for the staging and restaging of prostate cancer, but its wide anatomic coverage and tracer biology generate frequent incidental findings on both PET and the accompanying low-dose CT (LDCT). This narrative review is restricted in scope to fluorine-18 PSMA tracers because tracer-specific biodistribution and pitfall profiles shape what is perceived as incidentaloma: how confidently lesions can be categorized, and how often borderline findings trigger downstream testing, particularly for skeletal foci with [¹⁸F]-PSMA-1007. Specifically, [¹⁸F]-PSMA-1007 shows substantially higher rates of focal unspecific bone uptake than [⁶⁸Ga]-PSMA-11—reported in multicenter studies as affecting up to 40–50% of patients—which directly inflates the pool of potential incidentalomas and creates a tracer-specific false-positive problem with no parallel in gallium-68 practice. Additionally, [¹⁸F]-DCFPyL has different urinary clearance kinetics that affect bladder and ureteral uptake patterns, altering what qualifies as physiologic versus incidental in the pelvis. These differences mean that the threshold for Category B versus C classification—and the appropriate cascade-resistant language—must be tuned to the specific tracer in use. A framework built on [⁶⁸Ga]-PSMA-11 data would systematically underestimate bone pitfall frequency in [¹⁸F]-PSMA-1007 practice and could therefore paradoxically increase rather than reduce cascades if applied uncritically across tracers. These biodistribution differences have direct and concrete consequences for reporting behaviour and downstream management. In [¹⁸F]-PSMA-1007 practice, a focal bone uptake without a CT correlate in a mechanically plausible location—such as an anterior rib or vertebral endplate—should trigger Category B language in the report conclusion: the finding is documented in the body with explicit safety netting (“most consistent with unspecific uptake; no routine workup unless interval growth, new pain, or aggressive CT morphology”), and no referral to bone scintigraphy or MRI is generated. Without tracer-specific awareness, the same finding would typically prompt a reflex bone scan or whole-body MRI referral, delaying definitive prostate cancer management by weeks and adding imaging costs without diagnostic gain. By contrast, in [⁶⁸Ga]-PSMA-11 practice, an equivalent focal bone uptake without a CT correlate carries a higher prior probability of true metastatic disease given the lower background rate of unspecific uptake and should more often be reported at Category B with a lower threshold for escalation or more cautious language. For [¹⁸F]-DCFPyL, the higher urinary activity in the pelvis means that ureteral segments can mimic lymph node disease; recognizing this as a physiologic variant (Category C) rather than an equivocal nodal finding (Category B) avoids unnecessary pelvic MRI referrals that would otherwise be triggered by an uncontextualized report. In practical terms, the tracer-specific calibration of the overlay therefore changes not only the category assigned but also the specific safety-netting language and the escalation trigger, which directly modifies the downstream management pathway for each affected finding type. The scanned population—predominantly older men with a high prevalence of degenerative, inflammatory, and vascular abnormalities—creates substantial background noise that can drive low-value diagnostic cascades if incidental findings are communicated without actionability context. We integrate society-endorsed frameworks (EANM/SNMMI procedure guideline 2.0; E-PSMA; PSMA-RADS; and PROMISE/miTNM with miPSMA score) and propose a cascade-aware overlay for incidental findings that can be appended to existing PSMA reporting standards rather than replacing them. The A/B/C actionability overlay is a structured expert-consensus framework informed by existing evidence-based guidelines for specific finding types and by tracer-specific cohort data; it has not yet been prospectively validated as a standalone tool, and its current level of evidence is therefore analogous to a structured expert recommendation rather than an evidence-based clinical guideline. We operationalize a three-tier actionability scheme across PET- and CT-dominant findings, provide cascade-resistant language for conclusions, and clarify why SUVmax-only “probability scales” for lymph nodes are not recommended in routine reports. Three practical tables summarize PET incidental findings, lymph node reporting frameworks, and LDCT incidental findings, and two structured report templates are provided (concise and extended), with the extended version explicitly labelling actionability tiers and escalation triggers. Finally, we outline concrete AI use cases for standardization and triage while emphasizing governance to avoid the amplification of false positives and paradoxical growth of cascades. Full article

The reaction scheme of the partial oxidation of methane is still currently undetermined for many catalysts due to a lack of accurate experimental data to develop kinetic studies. In this work, a kinetic modeling study of partial oxidation of methane was performed using experimental data from the literature. A kinetic model is proposed, and a new set of kinetic parameters was obtained in view of the failed reproduction of a model from the literature. The kinetic parameters of the proposed model were calculated and determined by using an optimization approach based on non-lineal parameter estimation, proper selection of initial values of parameters, and sensitivity and statistical analyses. Experimental data from the literature obtained in a packed-bed reactor with a Pt/Al₂O₃ catalyst at reaction temperatures of 465–574 °C were used to develop the kinetic model. Experimental data were accurately predicted by the proposed model with determination coefficient of 0.988. Full article

Magnetic targeting of drug carriers is commonly studied at macroscopic scales, while its impact on drug transport across individual cell membranes remains poorly quantified. Here, we present a theoretical and numerical model of magnetically assisted drug transport across the membrane of a single tumor cell exposed to magnetic field gradients. Extracellular transport is described by an advection–diffusion equation that couples passive diffusion with magnetophoretic drift, whereas intracellular transport is governed by diffusion and first-order uptake kinetics. The cell membrane is modeled as a semi-permeable interface with finite permeability, providing explicit coupling between extracellular and intracellular domains. Assuming spherical symmetry, the coupled transport equations are solved using finite-difference schemes, with magnetic forcing represented through an effective drift velocity $v_{\mathrm{m}\mathrm{a}\mathrm{g}}$ and interpreted using the magnetic Peclet number. To enable a controlled comparison between healthy and tumor cells, identical geometric, diffusive, and magnetic parameters are used, while biological differences are introduced solely through membrane permeability and intracellular uptake rates. By separating cumulative membrane delivery from cumulative intracellular uptake, the model resolves ambiguities arising from heterogeneous uptake kinetics. The results show that magnetophoretic drift enhances near-membrane drug accumulation and effective transmembrane flux without modifying intrinsic membrane properties. Magnetic targeting therefore acts as a transport amplifier, magnifying pre-existing biological differences and producing a larger model-predicted delivery advantage in tumor cells. Overall, the framework identifies the magnetic Peclet number as the key parameter governing the transition from diffusion-dominated to drift-enhanced cellular drug transport. Full article

Diesel engine emissions remain a concern because of their environmental and health impacts. Homogeneous charge compression ignition experiments on low-speed two-stroke marine diesel engines are costly, risky, and limited by scarce transient data. To address this issue, a one-dimensional/zero-dimensional AVL BOOST-ANSYS CHEMKIN coupled framework was established for an MAN B&W 6S50MC low-speed two-stroke marine diesel engine, providing a reasonable approach under data-limited conditions. The framework provided key initial conditions for detailed chemical-kinetic analysis and was used to examine methyl decanoate (MD)/di-n-butyl ether (DBE) blends with 0–20% DBE. The results indicate that DBE addition alters the balance between aromatic growth and oxidative removal and enhances low-temperature chain branching, while the increased peak temperature raises nitrogen oxides (NO_X) emissions. To relate these mechanistic results to engineering evaluation, the weighting scheme of the IMO NO_X Technical Code 2008 test cycle was introduced. Pyrene and its isomers and NO_X were treated by weighted normalization, followed by Pareto analysis and TOPSIS methods. MD90 (90 vol% MD and 10 vol% DBE) showed the best emissions trade-off over a wide range of weighting settings, which may provide useful guidance for optimizing oxygenated fuel blending ratios. Full article

In this study, a mathematical model based on nonlinear differential equations was developed to describe nitrate (NO₃⁻) removal in a woodchip denitrification bioreactor treating tile drainage water. The model captures temperature-dependent denitrification kinetics and transport processes under variable operating conditions. The model was validated using pilot-scale experimental data collected at different inflow water temperatures. The results indicated a strong temperature dependence of nitrate removal efficiency, with higher performance at elevated temperatures due to increased microbial activity and reaction rates. After validation, numerical simulations using a finite difference scheme were performed to evaluate bioreactor performance under varying hydraulic and geometric conditions. The analysis focused on the effect of bioreactor length, assuming constant width and depth (1.0 m each). Results showed that increasing reactor length enhances NO₃⁻ removal by extending hydraulic retention time, although the effect becomes nonlinear due to substrate limitation along the flow path. Simulations further demonstrated that a target NO₃⁻ removal efficiency of approximately 40% can be achieved through different combinations of temperature, bioreactor length, and hydraulic loading, indicating a compensatory relationship between kinetic and design parameters. Overall, this study provides a predictive framework for optimizing bioreactor design and operation, offering practical guidance for improving nitrate removal in agricultural drainage systems. Full article

Vento Norte (VNOR; Portuguese for North Wind) is a downslope windstorm that develops over modest terrain in the central region of Rio Grande do Sul (RS), southern Brazil. The regional topography is characterized by an abrupt terrain transition with elevation differences of approximately 400–500 m. This atmospheric flow typically occurs during the cold season and is characterized by strong wind gusts, rapid warming, and drying of the planetary boundary layer (PBL). In this study, the performance of different PBL parameterization schemes in the Weather Research and Forecasting (WRF) model is assessed for simulating a VNOR event that occurred between 19 and 20 August 2021 in Santa Maria (SMA), RS. Five high-resolution numerical simulations were conducted using the Yonsei University (YSU), Asymmetric Convective Model version 2 (ACM2), Mellor–Yamada–Nakanishi–Niino level 2.5 (MYNN2.5), Quasi-Normal Scale Elimination (QNSE), and Three-Dimensional Turbulent Kinetic Energy (3DTKE) PBL schemes. Model results were evaluated against observations from a flux tower providing turbulence measurements, twice-daily radiosoundings, and hourly surface meteorological observations. Statistical metrics indicate that the MYNN2.5 scheme provided the most accurate representation of the nighttime stable boundary layer preceding the VNOR, as well as its onset and subsequent evolution. Although this study analyzes a single VNOR event and the results may be case-dependent, the overall performance of the MYNN2.5 scheme suggests that it is a promising option for the operational forecasting of VNOR events. These findings provide new insights into the ability of different PBL schemes to reproduce the mean boundary-layer structure and turbulence characteristics associated with downslope windstorms over modest terrain, contributing to the understanding of these events. Full article

This study investigates eddy currents in the dry cool superconducting MRI system by adopting a strong coupling multi-physics analysis method that integrates electromagnetic and mechanical fields. The 3D model is simplified based on the spatial distribution characteristics of the Lorentz force. A set of strong coupling matrix equations is derived by combining mechanical principles with Maxwell’s equations. The weak coupling scheme is implemented by applying displacement boundary conditions and validated through kinetic energy analysis. Through vector analysis, the origin of eddy power is explored, leading to the conclusion that the primary contribution to eddy power stems from the coupling between primary and secondary eddy currents. Furthermore, by analyzing the vector directions of primary and secondary eddy currents at specific mesh elements, the sign (positive or negative) of eddy power at different frequencies is characterized. The results show that the superposition of primary and secondary eddy currents produces positive power when they have a common directional component; conversely, the suppressive effect of secondary eddy currents results in negative power. This research deepens the understanding of the generation mechanism and influence of secondary eddy currents, providing guidance for subsequent dry cool superconducting MRI magnet optimization design. Full article

Polymer microsphere flooding is an effective enhanced oil recovery (EOR) technology. Its primary mechanism is characterized by a dynamic cycle of “migration, plugging, breakthrough, and remigration”, which enables effective in-depth profile control and selective plugging. However, constructing accurate mathematical models and obtaining stable numerical solutions for this process remain challenging. Based on the black-oil framework, a three-phase, five-component mathematical model is developed for water-microsphere dispersed system, including oil, gas, water phases and two microsphere components (pre-swollen and post-swollen), and accounting for swelling kinetics, adsorption, and water phase permeability reduction. The model is numerically solved using a fully implicit finite-difference scheme, and validated by numerical tests and a field-scale application. The numerical simulation results demonstrated an overall agreement rate of approximately 85% with experimental data. Mechanistic comparisons indicated that polymer microsphere flooding significantly improves sweep efficiency and oil recovery. Field-scale application further showed that polymer microsphere flooding, compared with conventional water flooding, increases the recovery factor by 3.49 percentage points, reduces the maximum water cut by about 9.34 percentage points, and raises the average daily oil production rate over the entire development period by 7.5 m³. The proposed model can provide theoretical basis for the field application of polymer microsphere flooding for in-depth profile control. Full article

This study presents the rational design of a visible-light-responsive TiO₂/polyaniline (PANI) nanofiber heterostructure via in situ oxidative polymerization to overcome the limited visible-light absorption and rapid charge recombination of TiO₂. Comprehensive characterization using XRD, FT-IR, XPS, SEM, UV–Vis DRS, and EIS confirmed the successful integration of TiO₂ nanoparticles within a conductive polyaniline nanofiber network, enabling efficient interfacial charge transfer. The optimized TiO₂/PANI-30 composite exhibited outstanding photocatalytic performance, achieving ~99% degradation of Basic Fuchsin dye within 40 min under visible light, significantly outperforming pristine TiO₂. The enhanced activity is attributed to improved visible-light absorption, reduced bandgap energy, and suppressed electron–hole recombination, supported by optical and electrochemical analyses. Kinetic studies indicated pseudo-first-order behavior, with TiO₂/PANI-30 showing the highest rate constant. Radical trapping experiments identified superoxide and hydroxyl radicals as the main active species, with •OH playing a dominant role. A direct Z-scheme charge transfer mechanism was suggested, preserving strong redox potentials and promoting reactive oxygen species generation. Additionally, the photocatalyst demonstrated excellent stability and reusability. These findings highlight the suggested potential of TiO₂/PANI systems as efficient and sustainable photocatalysts for wastewater treatment. Full article

Natural products display exceptional chemical diversity and a broad range of mechanisms of action that are not adequately captured by traditional classifications based on target class, pharmacological phenotype, or chemical scaffold. Such classification schemes often lead to fragmented understanding of mechanisms of action, obscuring the unified principles underlying different target systems while failing to recognize the stage-dependent mechanisms exhibited by the same molecule in varying contexts. Here, we propose a unified “space–interface–time” framework to classify the mechanisms of action by examining the physical principles through which natural products reshape the functions of different biomolecules. Within this framework for unifying the classification of natural product mechanisms of action, geometry-driven binding site occupancy and conformational constraints are assigned to the spatial dimension; induction or stabilization of multicomponent complexes and kinetic regulation of state lifetimes are assigned to the interfacial and temporal dimensions, respectively. Finally, we discuss the conceptual and technical challenges of bridging static structural snapshots with dynamic in vivo pharmacology, and highlight emerging opportunities offered by time-resolved structural methods and the integration of molecular dynamics, machine learning, and biophysical workflows for mechanism-guided drug discovery. Full article