Search Results (2,180)

The Zeta-Minimizer Theorem provides a fully deductive variational foundation for the hydrogen oxidation reaction (HOR) and oxygen reduction reaction (ORR) in proton exchange membrane fuel cells. Starting from three primitive thermodynamic axioms and the helical geometry of the phase functional, a multi-extent dynamical system is constructed that simultaneously treats the electrochemical reaction coordinates and the adsorption extents of the participating species at the solid–electrolyte interface. The combined Hessian of the phase functional yields a complete spectrum of relaxation rates whose eigenvalues and eigenvectors emerge directly from the solid blackbox constants C_k and the helical partition functions of the reactive species. Adiabatic elimination of the fast surface modes produces an effective single-extent description in which voltage (or overpotential) appears as the conjugate variable, exactly analogous to the role of pressure in the corresponding gas-phase ammonia synthesis framework. The resulting nonlinear rate law is thermodynamically consistent at all conditions, recovers the Butler–Volmer and Tafel forms as well-defined limiting cases, and incorporates the effects of temperature, dilution, and catalyst-specific interface constants without empirical activation energies or adjustable reaction orders. The framework therefore unifies equilibrium, kinetics, and modal dynamics of HOR and ORR within a single variational structure, offering a parameter-light, first-principles alternative to classical empirical electrocatalytic rate expressions while preserving transparent contact with established limiting laws. Full article

This study investigates the synergistic effects of compaction pressure and vapor-induced phase separation (VIPS) on the morphological, mechanical, and initial filtration properties of activated carbon/polyethersulfone composite block membranes. Membranes were fabricated using varying compaction pressures (5 and 10 kg/cm²) and VIPS exposure times (0 and 10 min) prior to direct non-solvent-induced phase separation (NIPS). Surface wettability analysis revealed that the optimized 50 wt.% activated carbon configurations were superhydrophilic (0° water contact angle), exhibiting instantaneous fluid absorption driven by strong capillary forces within the highly hygroscopic matrix. Morphological and gravimetric evaluations demonstrated that minimizing compaction (5 kg/cm²) and bypassing VIPS generated large macrovoids, resulting in the highest bulk internal porosity (61.05%) and maximum continuous gravity-driven water flux. Conversely, incorporating a 10-min VIPS exposure shifted the internal structure toward an interconnected sponge-like network. This structural transformation yielded the highest bovine serum albumin (BSA) rejection rate (12.97%) when paired with low pressure, as the network extended fluid residence time and maximized exposure to the activated carbon adsorption sites. Applying high compaction pressure (10 kg/cm²) to VIPS-treated membranes induced excessive polymer encapsulation of the active particles, significantly reducing separation efficiency while concurrently maximizing initial uniaxial tensile strength. Ultimately, these findings establish a foundational and highly tunable framework, demonstrating that calibrating mechanical compression alongside phase inversion dynamics balances permeability, adsorptive selectivity, and inter-particle binding cohesion for composite block membranes. Full article

The high-temperature sealing reliability of flange–bolt–gasket systems is governed by the coupled gasket leakage, flange cracking, and bolt yielding. This study investigates a DN200 PN40 (nominal diameter 200 mm and nominal pressure 4.0 MPa) weld-neck flange assembly operating under 300 °C superheated steam at 4 MPa internal pressure. Exploiting the assembly’s 12-fold cyclic rotational symmetry, a 1/12 periodic-sector finite element model with steady-state thermal–structural sequential coupling was developed in ANSYS Workbench and validated against the Omiya–Sawa 3-inch weld-neck flange benchmark at two levels (Level 1: bolt load vs. experiment; Level 2: 250 °C gasket contact pressure vs. reference finite element method (FEM)), with maximum errors below 1.5% in both levels; the benchmark thus establishes the reliability of the modeling procedure rather than constituting a direct experimental validation of the DN200 PN40 configuration. Using a central composite design, second-order response surface models (RSM) and Kriging surrogate models were constructed and compared, followed by Sobol global sensitivity analysis, multi-objective optimization using the non-dominated sorting genetic algorithm II (NSGA-II), and decision-making using the technique for order preference by similarity to ideal solution (TOPSIS), with bolt preload F and gasket width b as design variables. Baseline analysis revealed a differential contact pressure distribution—lower at the inner radius and higher at the outer radius—driven by a −0.308° flange rotation, identifying the inner gasket edge as the critical sealing failure path. RSM outperformed Kriging for the primary objective (mean absolute percentage error (MAPE): 0.72% vs. 3.61%), and the Pareto front collapsed to b = 19 mm. The TOPSIS-recommended optimum (F = 59,942 N, b = 19.00 mm), verified by ANSYS back-substitution, increased the minimum gasket contact pressure by 31.01% while reducing the flange membrane-plus-bending stress by 2.26%, achieving a coordinated improvement of both sealing performance and structural safety. Full article

The dopamine D₂ receptor (D2R) is one of the principal therapeutic targets for the treatment of schizophrenia and other neuropsychiatric disorders. Understanding how ligands with different pharmacological profiles interact with D2R is essential for the rational design of safer and more effective antipsychotic drugs. In this work, Molecular Dynamics (MD) simulations combined with Quantum Theory of Atoms in Molecules (QTAIM) analysis were employed to investigate the electronic nature of protein–ligand interactions in D2R embedded in a neuronal membrane environment. Representative agonists (dopamine and rotigotine) and antipsychotics from different generations (haloperidol, risperidone, and aripiprazole) were analyzed to identify interaction patterns associated with distinct pharmacological activities. The agonist-bound simulations revealed recurrent interactions involving the serine-rich region, whereas the antipsychotic-bound systems exhibited more persistent contacts within the central aromatic region of the binding pocket. These observations suggest ligand-associated interaction tendencies rather than universal determinants of agonism or antagonism. Furthermore, aripiprazole displayed a unique interaction profile characterized by enhanced coupling with the PIF connector, suggesting a distinct modulation of the TM6 toggle switch compared with other antipsychotics. The integration of MD and electron density topology revealed ligand-specific interaction networks associated with distinct pharmacological profiles at D2R. The interaction patterns identified in this study highlight characteristic interaction motifs associated with ligand-specific pharmacological profiles and provide mechanistic insights that may support the rational design of novel dopaminergic therapeutics. Full article

To address the persistent challenge of membrane wetting during oil-gas separation in transformer condition monitoring, an omniphobic composite membrane was developed to facilitate the reliable online detection of dissolved gases. An F-CNTs/Teflon AF/PVDF composite membrane, featuring a loofah-like hierarchical structure and omniphobic properties, was fabricated via spraying-deposition strategy on the polyvinylidene fluoride (PVDF) substrate. The morphology, surface chemical composition, wettability and stability of the F-CNTs/Teflon AF/PVDF composite membrane were systematically characterized. Subsequently, the oil-gas separation performance of the composite membrane was evaluated using standard transformer oil containing dissolved gases as the feed solution. The results indicated that fluorinated carbon nanotubes (F-CNTs) were successfully modified onto the membrane surface, creating a re-entrant morphology composed of an intersecting nanotube network that mimics the hierarchical architecture of a loofah. The F-CNTs/Teflon AF/PVDF composite membrane exhibited exceptional omniphobicity, achieving contact angles of 168.2 ± 1.5° and 127.5 ± 1.0° towards DI water and mineral insulating oil, respectively. Additionally, the loofah-inspired composite membrane demonstrated robust thermal and ultrasonic stability. In oil-gas separation tests, the omniphobic membrane displayed a rapid response and high efficiency for dissolved gas extraction, achieving dynamic equilibrium within 64 min. Furthermore, the modification improved permeation efficiency by 25.6%. These results suggest that the developed omniphobic membrane is a promising alternative for oil-gas separation in the condition monitoring of oil-filled electrical equipment. Full article

As the core component of an artificial kidney, a hemodialysis membrane can remove metabolic wastes and excess fluid from the blood while retaining essential proteins. Despite their essential role in blood purification, current hemodialysis membranes still show limited efficiency in clearing middle-molecule uremic toxins, especially β₂-microglobulin. Ordered mesoporous silica (SBA-15) was used as an inorganic pore-regulating additive to construct ordered mesoporous silica/polyethersulfone (PES) mixed-matrix membranes for separation applications. The incorporation of SBA-15 may help form additional effective transport pathways in the PES membrane by regulating pore formation, increasing membrane hydrophilicity, and improving apparent pore connectivity, thereby reducing the apparent transport resistance of middle-molecule solutes. As a result, the composite membranes achieved improved dialysis performance while maintaining high BSA retention. The SBA-15 loading was systematically optimized. Relative to the pristine PES membrane, the 7 wt.% SBA-15 membrane reduced the water contact angle from 65.1° to 49.0° and increased lysozyme reduction from 40.9% to 55.2%, with pure water permeability reaching 261.5 L m⁻² h⁻¹ bar⁻¹ and bovine serum albumin (BSA) retention remaining above 90%. These results suggest that SBA-15 may regulate the pore structure of PES membranes and improve apparent pore connectivity, thereby facilitating middle-molecule solute transport while maintaining high BSA retention. Full article

Catalytic nanozymes have emerged as a versatile class of engineered nanomaterials that combine enzyme-like catalytic activity with exceptional physicochemical stability, tunable composition, and scalable fabrication, offering significant advantages over natural enzymes for antimicrobial applications in food systems. Recent advances in materials engineering have enabled the development of nanozymes with enhanced catalytic efficiency, broad-spectrum antimicrobial activity, and improved resistance to harsh food-processing environments. Nevertheless, current research remains fragmented across diverse material platforms and application scenarios, while a comprehensive understanding of how engineering strategies govern catalytic performance, antimicrobial efficacy, and translational potential is still lacking. This review provides a critical and systematic analysis of catalytic nanozymes for antimicrobial food systems from a structure–activity relationship perspective. Emphasis is placed on the engineering principles that regulate enzyme-mimicking activities, including compositional tuning, crystal phase and facet engineering, defect creation, heterostructure construction, pore architecture, surface functionalization, and single-atom engineering. The relationships between these structural features and catalytic mechanisms, including peroxidase-, oxidase-, catalase-, and multi-enzyme-like activities, are discussed in relation to the generation of reactive oxygen species, membrane disruption, extracellular polymeric substance degradation, biofilm eradication, and pathogen inactivation. Representative applications in food-contact surface decontamination, antimicrobial packaging, fresh produce preservation, and intelligent food processing are critically evaluated using recent experimental evidence. Beyond antimicrobial performance, this review introduces a safe-by-design framework that integrates material engineering with toxicological assessment, nanoparticle migration, environmental fate, regulatory considerations, and scalable manufacturing. Emerging opportunities for artificial intelligence-assisted nanozyme design, high-throughput materials discovery, and data-driven optimization are also discussed as transformative approaches for accelerating industrial translation. By integrating materials science, catalytic mechanisms, food microbiology, and safety assessment, this review establishes a comprehensive framework for the rational development of next-generation catalytic nanozymes toward sustainable, effective, and industrially applicable antimicrobial food systems. Full article

Wound dressings play a crucial role in promoting tissue regeneration while protecting damaged tissue from microbial infections. The aim of this study is to produce antimicrobial PVA-chitosan membranes for wound dressing applications using Stevia rebaudiana Bertoni leaf extract (stevia) as a natural bioactive agent. Although widely recognized as a natural sweetener, stevia contains a high concentration of diterpene glycosides, particularly stevioside and rebaudioside A, together with phenolic compounds that contribute to its biological activities. Therefore, stevia was first evaluated against selected microorganisms and demonstrated effective antimicrobial activity. PVA-chitosan (P/Ch) membranes were prepared by solvent casting method by incorporating different amounts of stevia (P/Ch, P/Ch@20, P/Ch@40, and P/Ch@60). The antimicrobial activity of stevia was also successfully maintained in P/Ch membranes. Good antibacterial activity was observed against Bacillus subtilis and Escherichia coli, whereas the antifungal activity against Candida albicans was comparatively modest. Contact surface analysis showed complete bactericidal activity in Gram-negative and spore-forming bacteria. The cytocompatibility of the membranes was investigated by MTT assay. All formulations maintained a high cell viability (>80%) while the P/Ch@40 membrane increased the metabolic activity to above 100% at higher extract concentrations. In conclusion, stevia-incorporated membranes exhibited high antimicrobial activity, acceptable characteristic properties, and good cytocompatibility, suggesting that they are promising alternative biomaterials for tissue engineering applications. Full article

The global crisis of expanded polystyrene (EPS) waste and the rising demand for affordable water purification technologies necessitate the development of sustainable, high-performance filtration materials. This study reports the successful upcycling of post-consumer Styrofoam into functional nanocomposite membranes reinforced with nano-activated carbon (nAC). Fabricated via nonsolvent-induced phase separation (NIPS) with nAC concentrations ranging from 0 to 0.4 wt.%, the membranes were evaluated to determine the synergistic effects of nanoparticle loading on morphology and transport phenomena. Scanning electron microscopy (SEM) revealed a stable asymmetric architecture characterized by a dense selective skin layer and a porous support structure. The integration of nAC significantly enhanced both surface hydrophilicity and structural porosity. The 0.3 wt.% nAC loading yielded optimal results, achieving a minimum water contact angle of 70.03° and a maximum porosity of 93.17%. Consequently, hydraulic permeability reached a peak of 35.66 LMH/bar, an approximate 223% improvement over the pristine EPS baseline. Performance evaluations utilizing Spirulina platensis as a model biomass demonstrated an absolute rejection efficiency of 100% and a turbidity reduction to 0 NTU across all composite variations, confirming robust size-exclusion capabilities. These findings demonstrate that incorporating nAC effectively transforms recycled Styrofoam into a high-value, sustainable filtration medium, offering a highly efficient and low-cost solution for cyanobacteria harvesting and environmental remediation. Full article

The rising prevalence of chronic kidney disease (CKD) has intensified the demand for innovative blood filtration therapies. Hemoperfusion, which integrates membrane filtration with adsorbent technologies to sequester circulating uremic toxins, represents a promising therapeutic alternative. In this study, polyethersulfone (PES)-powdered activated carbon (PAC) composite membranes were fabricated via nonsolvent-induced phase separation (NIPS), and the molecular weight of polyethylene glycol (PEG) was optimized as a hydrophilic pore-forming agent. Dope solutions were formulated with 15 wt.% PES, 1 wt.% PAC, and 10 wt.% PEG at varying molecular weights (200, 400, 600, and 1000 Da). Comprehensive characterization revealed that PEG molecular weight significantly dictates the structural and functional performance of the resulting composites. The PEG 600 Da variant achieved an optimal balance of properties, characterized by homogeneous PAC dispersion, a peak water flux of 420.88 LMH/Bar, a water contact angle of 37.11°, and a porosity of 74.74%, while maintaining a high Bovine Serum Albumin (BSA) rejection of 90.87%. While increasing PEG molecular weight generally enhanced permeability through the formation of an open pore architecture, a performance trade-off was observed beyond the 600 Da threshold due to increased dope viscosity and altered phase inversion kinetics. These findings suggest that PEG 600-optimized PES-PAC membranes offer a high-performance, affordable platform for advanced hemoperfusion applications. Full article

Through multifaceted reprogramming, mitochondria, the fundamental organelles of eukaryotic cells, can drive the malignant growth of malignancies. They also control energy metabolism, redox balance, and cell fate determination. Due to its high heterogeneity and primary/acquired drug resistance, gastric cancer (GC), a highly deadly and common cancer worldwide, continues to present significant clinical treatment challenges. Current targeted and immunotherapy strategies have been unable to significantly improve long-term patient survival. Thus, the pathological roles and molecular mechanisms of mitochondrial dysfunction (including mutations in mitochondrial DNA, imbalances in mitochondrial dynamics, aberrant mitophagy, abnormalities in mitochondrial permeability transition pores, and metabolic disorders) in the development of GC are systematically reviewed in this article. The specific mitochondrial phenotypic remodeling of various molecular subtypes of GC, abnormalities in membrane contact interactions between mitochondria and other organelles, the regulatory roles of mitochondrial dysfunction in tumor microenvironment (TME) immune evasion, maintenance of tumor stemness, and ferroptosis, as well as their major effects on the malignant progression and treatment resistance of GC, are all thoroughly examined. In order to provide important theoretical references and novel research perspectives for identifying therapeutic targets with greater precision, clarifying resistance mechanisms, and developing novel combination strategies in GC, this article summarizes the current research status and translational potential of anti-GC therapeutic strategies targeting mitochondria. It also explores the translational challenges currently faced in this field and the core future research directions. Full article

Objectives: Malaria remains a major global health burden, particularly in endemic regions such as Djibouti, where Plasmodium falciparum and Plasmodium vivax co-circulate, complicating disease control strategies. Increasing resistance to current antimalarial drugs reduces treatment effectiveness and highlights the urgent need for new, safe, and affordable therapeutic agents. This study aimed to identify potential inhibitors from Djiboutian medicinal plants using an integrated in silico approach targeting key proteins from both parasite species. Methods: A library of 222 phytoconstituents was screened against Plasmodium vivax FK506-binding protein 35 (PDB ID: 3IHZ) and Plasmodium vivax dihydrofolate reductase–thymidylate synthase (PDB ID: 1J3K) using molecular docking. Top-ranked compounds were further analyzed for binding interactions and evaluated for drug-likeness and pharmacokinetic properties using QikProp in Maestro v11.5. Selected protein–ligand complexes were subjected to 100 ns molecular dynamics simulations, and their stability was assessed using multiple descriptors, including structural deviation, flexibility, compactness, solvent exposure, and hydrogen bond persistence. Results: Several phytoconstituents exhibited strong binding affinities, with docking scores ranging from −6.09 to −7.54 kcal/mol, outperforming the reference drug artemisinin. Interaction analysis revealed key hydrogen bonds and hydrophobic contacts with essential active-site residues. ADMET predictions indicated favorable pharmacokinetic profiles, including high oral absorption, good membrane permeability, and low predicted toxicity. Molecular dynamics simulations demonstrated stable behavior for most complexes, with compound 121 showing enhanced stability in the 1J3K system and compound 123 exhibiting consistent dynamic stability in the 3IHZ system. In contrast, compound 82 displayed greater structural fluctuations despite maintaining stable hydrogen bond interactions. Conclusions: The integration of molecular docking, ADMET prediction, and molecular dynamics simulations identified compounds 121 and 123 as the most promising antimalarial candidates, exhibiting an optimal balance of binding affinity, favorable pharmacokinetic properties, and dynamic stability. These findings highlight the potential of Djiboutian medicinal plants as a valuable source of novel antimalarial agents and provide a strong computational foundation for future experimental validation. Full article

This study presents the development of a proof of concept, functional hydrogel interface designed for the acquisition of physiological signals, such as electrocardiogram (ECG) and electromyography (EMG). The hydrogel is synthesized using chitosan extracted from the shells of Tenebrio molitor larvae through a sustainable acid–alkaline protocol, blended with glycerol, polyvinyl alcohol (PVA), and ionized with NaCl to enhance conductivity. The resulting hydrogel membranes were cast and cut into circular shapes to provide a uniform contact geometry. The fabrication process yielded flexible membranes exhibiting ionic conductivity and partial surface conformity and handling stability. The extracted chitosan was characterized by Fourier-transform infrared spectroscopy (FTIR), degree of deacetylation (DDA), and molecular weight determination. Mechanical characterization included compression and tensile testing, while electrical characterization was performed through impedance spectroscopy and comparison with a commercial hydrogel interface. Functional evaluation was conducted through ECG and EMG signal acquisition under controlled experimental conditions. Preliminary in situ ECG and EMG recordings demonstrated successful signal acquisition using the proposed hydrogel interface. Future work may further investigate the mechanical and electrical behavior of the hydrogel under broader experimental conditions, as well as the optimization of the hydrogel formulation and extended physiological signal acquisition. Studies may help further characterize its potential as a chitosan-based bio interface material for bioelectrical sensing applications. Full article

In this study, porous polyvinylidene fluoride (PVDF) hollow fiber (HF) membranes for membrane distillation applications were successfully prepared using TamiSolve^® NxG, an innovative lower-hazard solvent, through the non-solvent induced phase inversion technique. The influence of the bore fluid composition and bore fluid flow rate on membrane morphology and performance was systematically investigated while maintaining a fixed polymer dope formulation. The prepared hollow fibers were thoroughly characterized in terms of morphology, membrane thickness, porosity, contact angle, mechanical resistance, pore size, and pure water permeability. In addition, their performance was investigated through Direct Contact Membrane Distillation (DCMD) tests in order to evaluate their applicability in desalination processes. The developed PVDF HF membranes exhibited pore sizes comparable to those of commercial polypropylene (PP) membranes and achieved high permeate flux together with excellent salt rejection, demonstrating their promising potential for sustainable membrane distillation and desalination applications. Full article

To realize the commercial application of metal bipolar plates in proton exchange membrane fuel cells (PEMFCs), it is important to develop coatings that are both durable and have low interfacial contact resistance (ICR). In this study, atmospheric plasma spraying (APS) was utilized to prepare nickel–graphite (Ni–G) and copper–graphite (Cu–G) coatings on titanium bipolar plates. This study investigates the effect of different graphite contents on the phase composition, microstructure, corrosion resistance, and electrical conductivity of the coatings. The results show that higher graphite content leads to better performance. The potentiostatic corrosion current densities of the Ni–G and Cu–G coated bipolar plates are 1.05 × 10⁻⁴ A·cm⁻² and 0.91 × 10⁻⁴ A·cm⁻², respectively. Similarly, the ICR values of the coated bipolar plates are 25.2 mΩ·cm⁻² and 38.9 mΩ·cm⁻² before and after cathodic polarization for Ni–G, and 17.4 mΩ·cm⁻² and 21.2 mΩ·cm⁻² for Cu–G. These results suggest that metal–graphite coatings deposited by APS represent a viable strategy for titanium bipolar plates. Full article