Search Results (1,036)

In this work, we investigated the incorporation of a fluorescent side group, fluorescein octyl ester (FOE), in benzodithiophene-based donor–acceptor terpolymers as a strategy to modulate excited-state behavior. Three FOE-containing terpolymers (P2-iIa-c), obtained at different polymerization times, were systematically evaluated against an analogous material without the fluorescent pendant unit (P1-iI). Thermal analysis revealed good thermal stability and an increase in glass transition temperature upon FOE incorporation, suggesting restricted segmental mobility and increased conformational constraints within the conjugated backbone. Optical characterization showed distinct absorption spectra with reaction time and shorter fluorescence lifetimes for the FOE-containing materials, consistent with the presence of additional excited-state deactivation pathways and intramolecular energy transfer processes within the terpolymer backbone. An approximate estimation of energy transfer efficiencies (≈60–65%) suggested that such processes may be operative within the system. Cyclic voltammetry measurements showed only minor variations in HOMO and LUMO energy levels between P1-iI and P2-iIa-c series, indicating that the conjugated backbone predominantly determined the frontier orbital energies despite side chain modification. Furthermore, photocurrent measurements from the bilayer device configuration exhibited a systematic increase in photocurrent for the FOE-containing material, supporting the role of excitonic modulation, rather than significant changes in interfacial energetic alignment. These results suggest that fluorescent side chain incorporation provides an effective strategy for regulating exciton dynamics while maintaining the electronic structure of the donor–acceptor terpolymer. Full article

Single-molecular white circularly polarized luminescence emitters show promise for use in chiral displays and solid-state lighting, but their design remains challenging because broadband emission, exciton utilization, color balance, and chiroptical activity must be integrated within one molecule. Herein, we report a chiral single-molecular white emitter, DCz-PTZ, constructed through a π-interrupted strategy by combining a rigid spiro framework, an oxygen-bridged carbazole/cyanobenzene segment, and a phenothiazine donor. The interrupted conjugation suppresses excessive charge-transfer (CT) domination and enables dual emissive channels, including short-wavelength locally excited (LE) emission and long-wavelength CT emission. DCz-PTZ exhibits near-ideal white emission in dilute toluene solution with CIE coordinates of (0.33, 0.33), and maintains balanced dual emission in 5 wt% doped films with CIE coordinates of (0.32, 0.34). Photophysical studies support the assignment of the yellow emission to a thermally activated delayed fluorescence (TADF)-active CT state. The enantiomers show mirror-image circularly polarized signals with |g_lum| up to 2.9 × 10⁻³. Optimized white organic light-emitting diodes (WOLEDs) achieve color rendering index (CRI) up to 92 and a maximum external quantum efficiency (EQE_max) of 1.3%. This work demonstrates a π-interrupted molecular strategy for integrating dual emission, TADF exciton utilization, and circularly polarized electroluminescence (CPEL) in a single chiral emitter. Full article

Listeria monocytogenes is a ubiquitous Gram-positive bacterium responsible for listeriosis, a foodborne zoonotic disease affecting humans and animals. Although infection in immunocompetent individuals is often asymptomatic or limited to mild self-limiting gastroenteritis, Listeria monocytogenes may cause severe invasive disease in vulnerable groups, including pregnant women, neonates, elderly individuals, and immunocompromised patients. Although the incidence of listeriosis is relatively low compared with many other foodborne pathogens, the high hospitalization and mortality rates associated with clinical cases make this bacterium a major concern for food safety and public health. The evolutionary success of L. monocytogenes reflects the interaction between a conserved core genome and a dynamic accessory genome shaped by horizontal gene transfer (HGT), ecological selection, and expansion of specific clones. Transient intestinal carriage in humans and animals, potentially influenced by gut microbiome composition, creates ecological interfaces where plasmids, transposons, prophages, and integrative conjugative elements contribute to the exchange of antimicrobial resistance determinants, virulence factors, and stress tolerance systems. Virulence diversification is further influenced by the differential distribution of pathogenicity islands such as LIPI-1, LIPI-3, and LIPI-4 across specific clonal lineages. These evolutionary processes occur across interconnected farm, food-production, environmental, and clinical ecosystems consistent with the One Health framework. Advances in whole-genome sequencing have clarified lineage-specific gene flow, expansion of specific clones, and the dynamics of the resistome and mobilome in L. monocytogenes populations. This narrative review aims to synthesize current knowledge on the mobile genetic elements and ecological interfaces that shape horizontal gene transfer in L. monocytogenes. Its novelty lies in integrating antimicrobial resistance, virulence-associated genomic islands, stress adaptation, and gut microbiome-mediated selection within a One Health and metapopulation framework. The main message of this review is that HGT should be interpreted as a context-dependent contributor to L. monocytogenes adaptation, acting together with clonal background, ecological selection, and mobile genetic elements. Full article

Cutaneous infections and chronic inflammatory wounds remain difficult to treat because antimicrobial resistance, polymicrobial biofilms, excessive protease activity, oxidative stress, and impaired barrier repair collectively reduce the effectiveness of conventional topical therapies. Plant-derived antimicrobial peptides (AMPs) and peptide-associated bioactives offer antimicrobial, antibiofilm, immunomodulatory, and tissue reparative potential; however, their clinical translation is limited by proteolytic instability, poor stratum corneum penetration, short cutaneous residence time, formulation variability, cytotoxicity risks and limited human evidence. The key research gap is the lack of an integrated translational framework linking plant-derived peptide bioactivity with polymer engineering, advanced delivery systems, skin microenvironment biology, manufacturability, and regulatory feasibility. This review aims to critically evaluate the design principles, therapeutic mechanisms, delivery platforms, and translational barriers of plant-based peptide–polymer therapeutics for cutaneous infection and inflammation. We summarize major classes of plant-derived antimicrobial peptides, including defensins, cyclotides, thionins, hevein-like peptides, snakins, lipid transfer proteins, and knottin-type scaffolds, and examine engineering strategies such as self-assembly, aromatic N-capping, PEGylation, lipidation, dendritic architectures, and stimuli-responsive conjugation. We further discuss topical matrices, nanocarriers, liposomes, electrospun fibers, and surface-tethered biomaterials as delivery platforms for improving peptide stability, local retention, and controlled release. Finally, we identify key translational bottlenecks, including selectivity, toxicity, scalability, batch reproducibility, regulatory classification, and insufficient clinical validation. Mechanism-driven peptide optimization, quality-by-design manufacturing, standardized preclinical models, and controlled clinical trials will be essential for advancing these systems toward safe and effective dermatological therapies. Full article

The continuous rise in turbine inlet temperatures to maximize engine efficiency makes highly integrated composite cooling schemes essential, but their intricate thermal interactions pose formidable challenges for parameter optimization. In this study, an impingement–pin-fin–film configuration is extracted as a representative composite cooling unit from a double-wall blade and subjected to 3D steady-state RANS simulations under realistic engine conditions. The numerical results are then used to construct quadratic polynomial response surface surrogate models for multi-objective optimization. It is revealed that the blowing ratio dictates overall thermal performance primarily through internal cooling, and excessively high ratios weaken the film coverage. Geometrically, insufficient control over the spanwise ratio disrupts film coverage and breaks the continuity of internal cooling, thereby degrading both cooling effectiveness and structural thermal compatibility. Additionally, a critical region is located upstream of the film hole exit; the combination of an extremely thin solid wall and high heat transfer coefficients creates a localized over-cooled zone, severely constraining temperature uniformity. Ultimately, the optimization framework clarifies the coupled flow and heat transfer behaviors of the double-wall unit. It simultaneously maximizes area-averaged overall cooling effectiveness and temperature uniformity while minimizing coolant mass flow, revealing the key mechanism behind induced thermal stress concentrations. Full article

Background/Objectives: Superparamagnetic iron-oxide nanoparticles (SPIONs) bearing poly(methacrylate) brushes were synthesized via surface-initiated atom-transfer radical polymerization (SI-ATRP) as magnetically responsive nanoplatforms. Three brush architectures, poly(2-hydroxyethyl methacrylate) (PHEMA) and poly(poly(ethylene glycol) methacrylate) with six ethylene-oxide units (PPEGMA6) and ten units (PPEGMA10), were grown from a dopamine-anchored initiator and covalently loaded with methotrexate (MTX). Methods: Physicochemical characterization confirmed successful polymer grafting, tunable hydrodynamic size (185–1320 nm before MTX conjugation and 427–694 nm after), retained superparamagnetic properties (22–69 emu g⁻¹), and high drug payloads, with PPEGMA6 achieving 131 µg mg⁻¹. MTX conjugation induced partial compaction of the polymer shell yet maintained ζ-potentials conducive to colloidal stability. Results: In vitro assays showed negligible toxicity toward primary human fibroblasts, whereas MTX-decorated formulations induced a pronounced concentration-dependent cytotoxic effect in MCF-7 breast cancer cells, reaching 69% loss of viability—significantly higher than free MTX. Structure–activity analysis attributes the superior performance of PPEGMA6-MTX to its balanced brush density, high payload, and favorable surface charge. Conclusions: These findings demonstrate that precise modulation of polymer brush architecture via SI-ATRP yields SPION-based nanocarriers that integrate MRI visibility and the potential for magnetic guidance and targeted chemotherapy. The PPEGMA6-MTX construct is highlighted as a promising platform for future preclinical investigations. Full article

Spray impingement cooling is a well-established heat removal technique employed across a wide range of industrial processes. A particularly significant cooling regime arises when the temperature of the cooled surface surpasses the Leidenfrost temperature of the spray. Developing an accurate numerical framework for this regime holds considerable potential for optimising industrial applications such as cryogenic machining and spray quenching. This paper presents a Eulerian–Lagrangian Conjugate Heat Transfer (CHT) model tailored for spray impingement under Leidenfrost conditions. Two heat transfer sub-models are incorporated to characterise droplet–solid thermal interaction: the first, developed by Breitenbach, is grounded in a theoretical analysis of the droplet impingement process, while the second, proposed by Deb, relies on a semi-empirical correlation. Both models were validated against an experimental correlation obtained from a literature study on orthogonal water spray impingement, yielding mean relative errors of 3.54% for the Deb model and 5.2% for the Breitenbach model across a broad range of operating conditions and surface temperatures. Full article

Hydrogen sulfide (H₂S) is a toxic and biologically relevant gas, necessitating sensitive and interference-resistant detection methods for environmental monitoring. Here, we develop a donor–acceptor molecular platform incorporating a polarized conjugated double bond bridge and demonstrate its application, using YG2 as the representative probe, as a dual-peak ratiometric UV–Vis sensor for H₂S. UV–Vis spectroscopy, supported by ¹H NMR analysis, indicates HS^--induced interaction with the conjugated linkage, leading to disruption of π-conjugation, suppression the intramolecular charge-transfer (ICT) band at 409 nm, and enhancing the locally excited (LE) band at 279 nm. The ratiometric parameter log(Abs₂₇₉/Abs₄₀₉) affords a linear response over the concentration range of 1.0 × 10⁻⁶–1.0 × 10⁻⁴ M with a detection limit of 8.3 × 10⁻⁷ M, providing approximately an order-of-magnitude improvement in analytical sensitivity compared with single-wavelength methods, and the reaction reaches completion within ~10 s. YG2 exhibits excellent selectivity toward H₂S over common anions and enables accurate quantification in real water samples, with recoveries of 95.43–105.86% and relative standard deviations (RSDs) of 0.56–9.58%. These results suggest that YG2 is a rapid, self-calibrating, and spectroscopically interpretable ratiometric probe suitable for reliable H₂S detection in complex aqueous environments. Full article

Second-life lithium-ion batteries offer strong potential for sustainable stationary energy storage, but their practical reuse is limited by cell-to-cell heterogeneity, non-uniform heat-generation, and the resulting thermal safety risks. Conventional battery thermal management systems (BTMSs), which rely on fixed and uniformly distributed coolant flow, are not well-suited to the asymmetric thermal behaviour of aged battery packs. In this study, an adaptive liquid-cooling framework with locally regulated branch-level flow allocation is proposed for second-life prismatic LiFePO₄ battery modules. A three-dimensional transient conjugate heat transfer model was developed in COMSOL Multiphysics. The analysis was conducted on a 3 × 3 battery module under nine thermal heterogeneity scenarios, followed by a larger 5 × 4 module to evaluate scalability. The results show that thermal severity depends not only on heat-generation magnitude but also on the spatial arrangement of degraded cells. Under the most critical 3 × 3 configuration, the adaptive BTMS reduced the maximum temperature from 37.16 °C to 28.77 °C, corresponding to a reduction of about 8.38 °C, while limiting the cell-to-cell temperature difference to approximately 1.16 °C. A comparison with a conventional constant-flow cooling configuration in the larger 5 × 4 module further showed that adaptive branch-level coolant redistribution improves thermal uniformity under heterogeneous thermal loading by selectively directing cooling capacity toward thermally stressed regions. The results demonstrate the potential of demand-driven flow allocation as a distributed thermal-management strategy for heterogeneous second-life battery systems. Full article

Coke deposition on the inner wall of helical coils in organic heat carrier (OHC) furnaces imposes additional thermal resistance, which impairs heat transfer and may trigger tube over-temperature failure. However, the quantitative coupling among the coking degree, flow conditions, and wall temperature response in helical coils remains insufficiently characterized. To address this gap, a three-dimensional steady-state conjugate heat-transfer model that resolves the additional thermal resistance of the coke layer is established using computational fluid dynamics (CFD). A dimensionless coking degree ω, defined as the ratio of coke layer thickness to inner tube radius, is introduced to parameterize the deposition state. Parametric simulations are performed at ω = 0–20%, with oil inlet velocities of 1–3 m/s. As ω increases from 0% to 20%, the maximum outer wall temperature rises by 66.1% (344 °C to 572 °C), whereas the maximum inner wall temperature decreases by 6.5%. The inner–outer wall temperature difference increases by over two orders of magnitude (1.61 °C to 251 °C), and the heat absorption of thermal oil declines by 53.4%. Raising the inlet velocity lowers the outer-wall temperature under clean-wall conditions, whereas this cooling effect is markedly diminished under severe coking. These findings provide a quantitative basis for the early-stage diagnosis of coking and safety evaluation of OHC furnaces. Full article

Hardy-type averaging operators arise in real analysis, rearrangement theory, weighted inequalities, and Volterra integral equations. This paper develops a distribution-function transport on $(0,\infty )$ equipped with an atomless Borel measure $\mu$, showing that the cumulative map $\Phi \left(x\right)=\mu \left(\right(0,x\left]\right)$ implements a measure isomorphism onto Lebesgue measure under transparent support and continuity hypotheses. Under this transport, the Hardy averaging operator relative to $\mu$ is conjugate to the classical Hardy operator on $(0,\infty )$ with Lebesgue measure. The main contribution is the systematic transport principle: classical constants, extremizing sequences, weighted criteria, endpoint estimates, and resolvent information are transferred exactly to the $\mu$-scale. We establish sharp $L^p\left(\mu \right)$ bounds, sharp power-weight extensions in $L^p\left({\Phi }^{\gamma }d\mu \right)$ for $-1<\gamma <p-1$, a transported one-weight Hardy class beyond powers, endpoint weak and strong estimates, spectral interpretation of the Volterra threshold, and numerical illustrations for the transported constants and a Volterra feedback equation. Full article

In this work, a partitioned coupling algorithm is developed by integrating the improved discrete velocity method (IDVM) with the lattice Boltzmann flux solver (LBFS) to address conjugate heat transfer (CHT) in microscale systems across all flow regimes. Specifically, the flow field is solved by the IDVM, generating a heat flux that acts as a Neumann boundary condition at the interface for the solid domain. Subsequently, the LBFS calculates the thermal distribution inside the solid, and the updated temperature at the interface is then applied to the fluid computations as a Dirichlet condition. The proposed framework effectively combines the strengths of the IDVM in modeling rarefied gas flows with the advantages of the LBFS in handling heat conduction in complex geometries. Crucially, the current approach implicitly captures temperature jump discontinuities at the conjugate boundary, bypassing the requirement for supplementary jump conditions. To evaluate its performance, several CHT test cases involving rarefied gas in microchannels were conducted. Computational evidence suggests that the scheme is robust across diverse flow regimes. Full article

This study presents an AI-assisted thermodynamic and computational fluid dynamics (CFD) evaluation of a β-type Stirling engine to improve its thermal efficiency and indicated power output. The engine performance was investigated using Restricted Dimensions Thermodynamics (RDT), the Schmidt thermodynamic model, and three-dimensional CFD simulations under various operating and geometric conditions. Key parameters including rotational speed, phase angle, piston diameter, displacer stroke, porosity, and charged pressure were systematically analyzed to determine their influence on engine behavior. A feed-forward artificial neural network (ANN) trained using the Levenberg–Marquardt optimization algorithm was integrated with CFD-generated datasets to predict engine performance and accelerate the optimization process. The AI-assisted optimization was coupled with the Variable Step-size Simplified Conjugate Gradient Method (VSCGM) to identify near-optimal operating conditions while reducing computational cost. Simulation results demonstrated that the optimization process improved the indicated power from 180.33 W to 185.44 W and increased thermal efficiency from 10.32% to 11.54%. The results also showed close agreement between predicted and experimental pressure–temperature profiles, confirming the reliability of the proposed methodology. Furthermore, CFD analyses revealed that increasing piston diameter and optimizing porosity enhanced heat transfer and pressure distribution within the engine chambers, resulting in improved thermodynamic performance. The proposed AI-driven framework provides a reliable and computationally efficient approach for the design and optimization of advanced β-type Stirling engines operating under realistic thermal conditions. Full article

Entropy generation analysis provides a thermodynamic framework for quantifying irreversibility in thermal systems. However, most existing second-law studies rely on simplified boundary conditions and do not consider fully coupled conjugate heat transfer involving fluid convection, wall conduction, and external heat exchange. Consequently, thermodynamic assessments under realistic conditions remain limited. This study presents an entropy generation-based assessment of turbulent conjugate heat transfer in circular pipes by considering the combined effects of wall thickness ratio (0.02–0.08), wall thermal conductivity (0.2–400 W/m·K), and external convection (5–100 W/m²·K). A three-dimensional steady RANS-based conjugate heat transfer model is employed, and entropy generation is evaluated to quantify irreversibility within fluid and solid domains. The results indicate that wall-related thermal resistances significantly affect thermodynamic performance. Variations in wall conductivity lead to approximately 15–20% changes in total irreversibility, while increasing external convection from 5 to 20 W/m²·K results in up to 25–30% variation. Increasing wall thickness enhances conductive entropy generation, whereas higher Reynolds numbers increase overall irreversibility. These findings demonstrate that the Biot number is a key parameter governing irreversibility distribution. The results provide energy-efficient design insights for optimizing thermally coupled engineering systems under realistic operating conditions. Full article

This study presents a controlled three-dimensional conjugate CFD comparison of counter-flow and parallel-flow concentric tube heat exchangers under identical Reynolds number conditions (Re = 1000–2000). By isolating the flow configuration as the only varying parameter, the intrinsic influence of flow arrangement on thermo-hydraulic performance is systematically evaluated. Unlike enhancement-focused studies involving geometric modification or advanced working fluids, the present study focuses exclusively on the influence of flow arrangement under identical operating conditions. The analysis focuses on heat transfer rate, outlet temperature distribution, pressure drop, thermo-hydraulic performance index, and a normalized heat transfer ratio (Ψ). The results show that the counter-flow configuration consistently enhances heat transfer by 3.17–4.29% compared to parallel-flow operation, while maintaining nearly identical pressure-drop values. This improvement is attributed to the preservation of a higher logarithmic mean temperature difference (LMTD) along the exchanger length, sustaining the thermal driving force under laminar flow conditions. In contrast, the parallel-flow configuration exhibits a rapid decay in temperature difference near the inlet region, limiting effective heat transfer. Although heat transfer increases with Reynolds number in both configurations, the thermo-hydraulic performance index decreases due to the relatively higher increase in hydraulic resistance. Comparison with classical laminar flow behavior confirmed the physical consistency and reliability of the numerical model. The findings demonstrate that counter-flow arrangement provides a measurable thermal advantage without additional hydraulic penalty. The study offers a physically consistent and practically relevant framework for the design and optimization of concentric tube heat exchangers used in engine cooling and waste heat recovery applications. Full article