Search Results (5,457)

Bio-based bismaleimide (BMI) resins can reduce environmental impact and impart intrinsic flame retardancy, but achieving a high glass transition temperature (Tg) remains challenging. Here, we replace the conventional petrochemical co-monomer O,O′-diallyl bisphenol A (DABPA) with a synthesized tri-allyl derivative of curcumin (AEC) in 4,4′-bismaleimidodiphenylmethane (BDM)-based resins. The AEC monomer, synthesized via exhaustive O- and C-alkylation of curcumin, acts as a trifunctional crosslinker. By systematically varying the imide:allyl molar ratio, we optimized the network properties. We optimize the network’s thermal and fire-safety properties. The optimized formulation (BDM: AEC = 1:0.87, denoted BA-0.87) yields 43.06% char at 800 °C and reduces the peak heat release rate (PHRR) by 13.2% compared to the conventional BDM/DABPA control (BD-0.87). Meanwhile, BA-0.87 passes UL-94 V-0 with no dripping and attains a Tg above 400 °C—nearly 100 °C higher than BD-0.87. These enhancements arise from curcumin’s rigid conjugated structure, which increases crosslink density and promotes char formation during decomposition. Our work demonstrates a viable, bio-derived pathway to engineer BMI resins that simultaneously improve thermal stability and intrinsic flame retardancy. Such resins are promising for demanding aerospace and high-temperature electronic applications that require both fire safety and stability. Full article

Based on true triaxial loading experiments and particle flow numerical simulations (PFC3D), this study systematically analyzes the mechanical behavior and failure mechanisms of granite under the influence of stress difference (deviatoric stress). The experimental results indicate that increasing deviatoric stress reduces peak strength, axial strain, and lateral strain, promoting rock failure with less deformation and dilatancy. An energy analysis reveals that higher deviatoric stress suppresses peak energy accumulation, with a greater proportion of energy being dissipated through crack initiation and propagation. Macroscopic observations show that failure surfaces develop combined tensile-shear cracks, evolving into distinct “V” shapes as deviatoric stresses increase. Numerical simulations demonstrate that intermediate principal stress plays a dual role, initially facilitating, then inhibiting, and finally promoting rock failure with its continuous increase. Microscopically, tensile cracks dominate during pre-peak stages, while rapid crack coalescence in the post-peak stage leads to the formation of throughgoing V-shaped failure zones. Particle displacement analysis reveals that deformation concentrates along the minimum principal stress direction, with the displacement vectors ultimately forming a V-shaped boundary that delineates the failure zone. The research provides comprehensive insights into the macro-meso failure characteristics of hard rock under true triaxial conditions, offering valuable guidance for stability prediction and control in underground rock engineering projects such as water-sealed storage caverns. Full article

Triplexes (TRX) are a class of flipons that can form due to the interaction of RNA with B-DNA. While many proteins have been proposed to bind triplexes, structural models of these interactions do not exist. Here, I present AlphaFold V3 (AF3) models that reveal interactions between the high-mobility group protein B1 (HMGB1), HNRNPU (SAF-A), TP53, ARGONAUTE (AGO), and REL domain proteins. The TRXs result from the sequence-specific docking of RNAs to DNA via Hoogsteen base pairing. The RNA and DNA strands in apolar TRX are oriented in the opposite 5′ to 3′ direction, while copolar TRX have RNA and DNA strands pointing in the same 5′ to 3′ direction. TRXs can incorporate different RNA classes, including long noncoding RNAs (lncRNAs), short RNAs, such as miRNAs, piRNAs, and tRNAs, nascent RNA fragments, and non-canonical base triplets. Many pathways regulated by TRX formation have evolved to constrain retroelements (EREs), which are both an existential threat to the host and a source of genotypic variation. TRXs help set the boundaries of active chromatin, repressing the expression of most EREs, while depending on other flipons to modulate cellular programs. The TRXs help nucleate folding of intrinsically disordered proteins. Full article

Titanium suboxide (TSO) catalysts offer remarkable activity toward pollutant degradation due to their stability at positive potentials, which enables the formation of reactive oxygen species. Herein, TSOs are prepared directly on the surface of Ti mesh, which also serves as the current collector. The evolution of different TSO surface species during temperature treatment is monitored using micro-Raman spectroscopy. The electrochemically active surface area is determined using cyclic voltammetry (CV) and shows a decrease from 9.3 cm² to 1.1 cm² upon increasing temperature, corresponding to the transformation of TSO as seen in micro-Raman spectroscopy. Impedance spectroscopy revealed nearly identical values (≈29 Ohm) for the charge transfer resistance during OER, indicating the presence of the same active centers on the surface. The electrode potential window toward water splitting is examined using oxygen and hydrogen evolution reactions (OER and HER). The Tafel slopes are in the range 400–600 mV dec⁻¹ for OER and 340–440 mV dec⁻¹ for HER, with higher values being desirable in pollutant degradation applications. Onset potential shifted to slightly more negative values with increasing temperature treatment, with samples treated at 850 °C and 950 °C enabling almost tenfold higher currents at the same potential values. The hydrogen evolution potential lies within the optimal region for H* radical formation around −1.2 V vs. RHE. Surface-formed TSOs represent promising biofunctional materials for pollutant degradation. Full article

This study demonstrates a proof-of-concept microbial electrochemical system (MES) that integrates a Geobacter sulfurreducens anodic biofilm with Actinobacillus succinogenes cathodic electro-fermentation. The anode, poised at 0 V versus Ag/AgCl, supported extracellular electron transfer from acetate oxidation, yielding a coulombic efficiency of up to 72.9%. When the cathode was switched from an abiotic ferricyanide sink to A. succinogenes medium containing neutral red, current increased sharply, reflecting mediator-assisted electron transfer. Cathodic metabolism showed a redirection in flux: succinate selectivity improved by 9.9%, increasing from 42.9% to 52.8% of input carbon, while formate and acetate decreased by 7.8% and 3.0%, respectively, without loss in overall carbon recovery. This improvement in succinate selectivity is industrially relevant in that it not only increases succinate yield but also lowers separation costs due to lower byproducts (formate and acetate). These results reveal that a poised G. sulfurreducens anode can sustain sufficient current to influence A. succinogenes product distribution, supporting the feasibility of biologically integrated MES-electro-fermentation. Potential hydrogen evolution, which could possibly contribute to increased succinate selectivity, was a thermodynamic possibility rather than a confirmed pathway. Future work was proposed to resolve electron partitioning, mediator kinetics, and cross-feeding interactions. Full article

A targeted modification approach involving the synthesis of Ce/C co-doped TiO₂ aerogels (CeCTi) via a sol–gel method combined with supercritical CO₂ drying and subsequent heat treatment is employed to enhance the photocatalytic CO₂ reduction performance of cost-effective and stable TiO₂ aerogels. The results demonstrate that the CeCTi exhibits a pearl-like porous network structure, an optical band gap of 2.90 eV, and a maximum specific surface area of 188.81 m²/g. The black aerogel sample shows an enhanced light absorption capability resulting from the Ce/C co-doping, which is attributed to the formation of oxygen vacancies. Under simulated sunlight irradiation, the production rates of CH₄ and CO reach 27.06 and 97.11 μmol g⁻¹ h⁻¹ without any co-catalysts or sacrificial agents, respectively, which are 82.0 and 5.7 times higher than those of the pristine TiO₂ aerogel. DFT reveals that C-doping facilitates the formation of oxygen vacancies, which introduces defect states within the calculational band gap of TiO₂. The proposed photocatalytic mechanism involves the light-induced excitation of electrons from the valence band to the conduction band, their trapping by oxygen vacancies to prolong the charge carrier lifetime, and their subsequent transfer to adsorbed CO₂ molecules, thereby enabling efficient CO₂ reduction, which is experimentally supported by photoluminescence measurements. Full article

The microevolutionary pathways and molecular mechanisms by which the important pathogen Vibrio parahaemolyticus acquires resistance in the aquatic environment under continuous selective pressure from quinolone antibiotic residues are still unknown. Here, the study successfully simulated the long-term pressure of antibiotic residues in aquaculture by susceptible V. parahaemolyticus (VPD14) which was isolated from seafood, to a 30-day in vitro induction with sublethal concentrations of levofloxacin, which yielded the mutants (VPD14M). A phenotypic analysis revealed that VPD14M exhibited resistance to ampicillin, levofloxacin and ciprofloxacin, compared to VPD14. These changes were accompanied by adaptations, including a decreased growth rate and an enhanced biofilm formation capacity. Whole-Genome Sequencing identified that the acquired resistance was primarily attributable to key point mutations in three Quinolone Resistance-Determining Regions (QRDRs). Specifically, a G → T substitution at nucleotide position 248 in the gyrA gene, leading to a serine-to-isoleucine substitution at the 83rd amino acid position (Ser83Ile) of the DNA gyrase subunit A; a C → T substitution at position 254 in the parC gene, resulting in a serine-to-phenylalanine substitution at position 85 (Ser85Phe) of the topoisomerase IV subunit A; and a C → T substitution at position 2242 in the gyrB gene, causing a proline-to-serine substitution at position 748 (Pro748Ser) of the DNA gyrase subunit B. Collectively, the study demonstrated that sublethal antibiotic levels rapidly drive quinolone resistance in V. parahaemolyticus, and the specific mutations identified offer critical support for resistance monitoring and seafood safety alerts. Full article

Vanadium carbide (V₂C) MXene shows great potential for addressing challenging implant-associated infections in bone regeneration due to its strong photothermal conversion efficiency. However, its photothermal efficacy is restricted to the near-infrared I (NIR-I) region due to a limited absorption range. To address this, we designed platinum nanoparticle-decorated V₂C heterostructures (Pt@V₂C) via an in situ growth method, leveraging Pt’s plasmonic and catalytic properties to extend the photoresponse to the NIR-II window. Subsequently, Pt@V₂C was integrated into poly-L-lactic acid (PLLA) to fabricate PLLA-Pt@V₂C scaffolds with photothermal antibacterial function by selective laser sintering. The optimized PLLA-Pt@V₂C scaffold achieves a record photothermal conversion efficiency (56.03% at 1064 nm), triggering simultaneous hyperthermia (>52 °C) and catalytic ·OH radical generation. In vitro studies demonstrate exceptional antibacterial efficacy against Staphylococcus aureus and Escherichia coli, achieving over 99% killing rates upon 1064 nm near-infrared irradiation. Furthermore, the scaffold demonstrated significant inhibition of biofilm formation, achieving over 90% reduction in biofilm biomass. Moreover, the scaffold demonstrated high cell viability, confirming its dual functionality of potent bactericidal activity and biocompatibility that supports tissue regeneration. This work provides a feasible strategy for combating implant-associated infections. Full article

Background/Objectives: Pancreatic ductal adenocarcinoma (PDAC) exhibits poor clinical response to gemcitabine, largely due to intrinsic and acquired mechanisms of chemoresistance. Identifying agents capable of enhancing gemcitabine efficacy without increasing cytotoxicity remains an unmet therapeutic need. Here, we characterise a small drug sensitiser molecule, B12, and evaluate its potential to sensitise PDAC cells to gemcitabine. Methods: Gemcitabine’s dose–response was assessed by MTT assay to determine IC₅₀ values and dose-modifying factor (DMF). Phenotypic consequences of co-treatment were examined using colony formation and wound scratch assays. Mitochondrial membrane potential (JC-1) and apoptosis (Annexin V/PI) were measured using flow cytometry. Transcriptomic profiling was performed using mRNA-seq with differential expression analysis and pathway enrichment (KEGG/GSEA). NF-κB activity was assessed by nuclear and cytoplasmic fractionation of p65, and RT-qPCR validation of NF-κB associated target genes. Results: B12 alone displayed minimal cytotoxicity in the PANC-1 cell line and normal pancreatic ductal HPDE cells, yet shifted the gemcitabine dose–response curve in PANC-1 cells, reducing the IC₅₀ and yielding a dose-modifying factor of 1.39. Functionally, B12 enhanced gemcitabine-induced suppression of colony formation and reduced wound closure relative to gemcitabine alone. The co-treatment also increased both mitochondrial depolarisation and apoptotic cell populations, with increased cell proliferation inhibition over time. Transcriptomic profiling identified a set of B12-associated genes downregulated both in B12-treated and B12 + gemcitabine conditions, including factors linked to growth, survival, inflammation, metabolism, and drug inactivation. Gene set enrichment analysis revealed negative enrichment of NF-κB associated pathways during B12 co-treatment. Consistently, nuclear-cytoplasmic fractionation showed that B12 reduced gemcitabine-induced nuclear accumulation of p65, accompanied by decreased expression of NF-κB associated targets such as BCL2L1, CCL20, SLC2A1, and MAP3K14. Conclusions: In PDAC cell models, B12 enhances gemcitabine cytotoxic response while displaying minimal intrinsic toxicity under the conditions tested. The sensitising phenotype is accompanied by increased apoptotic susceptibility and is associated with reduced NF-κB signalling at the pathway, transcript, and p65 nuclear localisation levels. However, to establish causality, the lack of sensitisation in HPDE cells will require further validation. Full article

High-quality BaTiO₃ nanopowders were synthesized via a sol–gel method using butyl titanate and barium serving as precursors. This study systematically investigates the influence of calcination temperature (600–1000 °C) and gel aging time (2–10 h) on the phase evolution and microstructure of the nanoparticles. A pure tetragonal phase with a high tetragonality (c/a ratio of 1.0100) and an average particle size of 140 nm was achieved at 1000 °C. X-ray photoelectron spectroscopy and Ultraviolet–Visible diffuse reflectance spectroscopy analyses revealed that high-temperature calcination induced the formation of oxygen vacancies and Ti³⁺ defects, leading to a narrowing of the optical bandgap from 3.01 eV to 2.98 eV. An optimal aging time of 4 h yielded uniform nanoparticles with a high specific surface area, whereas prolonged aging (>6 h) resulted in the re-emergence of BaCO₃ impurities and severe agglomeration due to the formation of a rigid gel network. This work provides a precise processing window for fabricating high-purity, highly tetragonal BaTiO₃ nanopowders suitable for the next generation of miniaturized electronic devices. Full article

Zinc oxide (ZnO) nanostructures were synthesized via a hydrothermal method by systematically varying the reaction time (6–24 h) while maintaining all other parameters constant. The morphological evolution progressed from nanoparticles to nanoneedles, nanoflakes, and nanoplates with increasing reaction duration. X-ray diffraction and Raman spectroscopy confirmed the formation of hexagonal wurtzite ZnO for all samples, accompanied by a gradual shift in the preferred growth orientation from the c-axis to the a-axis. The optical characterization revealed a pronounced dependence of the band gap and the defect density on the synthesis time, with the nanoflakes obtained at 12 h exhibiting a narrowed band gap of 2.9 eV and an enhanced visible light absorption. The photocatalytic degradation of methylene blue followed zero-order kinetics, where the ZnO nanoflakes achieved the highest rate constant (k₀ = 0.01893 min⁻¹). The enhanced activity is attributed to the combined effects of a reduced band gap, an increased surface area, the coexistence of ZnO/Zn(OH)₂ phases, and a defect-assisted charge separation. Full article

Polyamide 6 is an important engineering thermoplastic; however, its practical use is often constrained by its high flammability. Although aluminum diethylphosphinate is widely employed as a flame retardant for polyamide 6, its relatively slow char-forming kinetics hinders the attainment of the stringent 750 °C glow-wire ignition temperature required for electrical applications at moderate loadings. To address this limitation, a synergist was fabricated via the self-assembly of phytic acid, benzoguanamine, and ZnSO₄·7H₂O and subsequently incorporated to enhance the char-forming capability and flame retardancy of polyamide 6/aluminum diethylphosphinate composites. The results revealed that the synergist acted as an efficient charring promoter, improving flame retardancy. At a total loading of 15 wt%, the composite reached a UL-94 V-0 rating and high limiting oxygen index of 30.7%. Cone calorimetry data indicate that the peak heat release rate decreased by 34.0%, and the smoke production rate decreased by 33.3% compared with the polyamide 6/aluminum diethylphosphinate composites. Mechanistic analysis indicated that the synergist catalyzed the carbonization of the polyamide 6, enabling the formation of a dense thermally insulating char barrier in the condensed phase. Notably, the optimized formulation achieved a glow-wire ignition temperature of 750 °C, demonstrating its strong potential for high-safety electrical applications. Full article

Precise control over nanostructure evolution is critical for optimizing the electrochemical performance of pseudocapacitive materials. In this work, Nb₂O₅ nanostructures were synthesized via a time-engineered hydrothermal route by systematically varying the reaction duration (6, 12, and 18 h) to elucidate its influence on structural development, charge storage kinetics, and supercapacitor performance. Structural and surface analyses confirm the formation of phase-pure monoclinic Nb₂O₅ with a stable Nb⁵⁺ oxidation state. Morphological investigations reveal that a 12 h reaction time produces hierarchically organized Nb₂O₅ architectures composed of nanograin-assembled spherical aggregates with interconnected porosity, providing optimized ion diffusion pathways and enhanced electroactive surface exposure. Electrochemical evaluation demonstrates that the NbO-12 electrode delivers superior pseudocapacitive behavior dominated by diffusion-controlled Nb⁵⁺/Nb⁴⁺ redox reactions, exhibiting high areal capacitance (5.504 F cm⁻² at 8 mA cm⁻²), fast ion diffusion kinetics, low internal resistance, and excellent cycling stability with 85.73% capacitance retention over 12,000 cycles. Furthermore, an asymmetric pouch-type supercapacitor assembled using NbO-12 as the positive electrode and activated carbon as the negative electrode operates stably over a wide voltage window of 1.5 V, delivering an energy density of 0.101 mWh cm⁻² with outstanding durability. This study establishes hydrothermal reaction-time engineering as an effective strategy for tailoring Nb₂O₅ nanostructures and provides valuable insights for the rational design of high-performance pseudocapacitive electrodes for advanced energy storage systems. Full article

Large outcrops of ophiolites from exposed land surfaces can potentially impact the geochemistry of much greater areas through transport and weathering. Derived soil and sediments contain significant concentrations of heavy metals, including chromium and nickel. In the context of environmental risk analysis, there is a necessity to obtain more information about the distribution of Cr and Ni in serpentine rocks and their derived associated geological matrices, and about how easily Cr could be released and then oxidized in the environment, causing pollution of groundwater. The aim of this study was to evaluate the distribution of Cr and Ni in the geochemical fractions containing Fe and Mn and the role of Fe and Mn oxides (crystalline and non-crystalline) in redox processes leading to the formation of Cr(VI) during serpentine soil weathering. Through the combination of chemical selective sequential extraction (SSE) and X-ray diffraction, solid samples belonging to ophiolitic rocks and their derived soils and sediments in southern Tuscany were investigated. The applied SSE method followed the established extraction scheme commonly used in sequential selective extraction procedures. The extraction was accomplished in seven successive steps, using appropriate reagents to destroy the binding agents between the target metal and the specific soil fraction to release the heavy metals selectively from their structural context. The results indicated significant differences in the availability and mobility of Cr and Ni in soils, with Cr concentrations ranging from 200 to 950 μg/g and Ni from 274 to 665 μg/g in reactive fractions. Cr is tightly bound to well-crystallized Fe-oxides and primary rock-derived phases, whereas Ni is substantially more mobile, being mainly controlled by Mn-oxides and amorphous Fe-oxides. Weakly acidic solutions or systems with high redox potential increase Cr and Ni mobility in the environment due to Fe/Mn hydroxides produced by the weathering of serpentinites. An ORP higher than 1000 mV leads to the formation of Cr(VI) by oxidation of Cr(III), increasing the mobility of Cr in groundwater and the hazard for human health. The analytical activity carried out in this research can be used to identify the potential risk of Cr(VI) release in groundwater from serpentine and derived geomaterials. Full article

During the extrusion of novel nickel-based powder superalloy bars, the die is subjected to elevated temperatures, high pressures, and severe friction, which readily lead to abrasive wear and thermal-fatigue damage. These failures deteriorate the quality of the extruded products and significantly shorten the service life of the die. Frequent repair and replacement of the tooling ultimately increase the overall manufacturing cost. This study investigates the friction and wear behavior of H13 and 5CrNiMo hot-work tool steels under extreme transient high-temperature conditions by combining finite element simulation with tribological testing. The temperature and stress distributions of the billet and key tooling components during extrusion were analyzed using DEFORM-3D. In addition, pin-on-disk friction and wear tests were conducted at 1000 °C to examine the friction coefficient, wear morphology, and subsurface grain structural evolution under various loading conditions. The results show that the extrusion die and die holder experience the highest loads and most severe wear during the extrusion process. For 5CrNiMo tool steel, the wear mechanism under low loads is dominated by mild abrasive wear and oxidative wear, whereas increasing the load causes a transition toward adhesive wear and severe oxidative wear. In contrast, H13 tool steel exhibits a transition from abrasive wear to severe oxidative wear. In 5CrNiMo steel, friction-induced recrystallization, grain refinement, and softening lead to the formation of a mechanically mixed layer, which, together with a stable third-body layer, markedly reduces and stabilizes the friction coefficient. H13 steel, however, undergoes surface strain localization and spalling, resulting in persistent fluctuations in the friction coefficient. The toughness and adhesion of the oxide film govern the differences in wear mechanisms between the two steels. Owing to its higher Cr, V, and Mo contents, H13 forms a dense but highly brittle oxide scale dominated by Cr and Fe oxides at 1000 °C. This oxide layer readily cracks and delaminates under frictional shear and thermal cycling. The repeated spalling exposes the fresh surface to further oxidation, accompanied by recurrent adhesion–delamination cycles. Consequently, the subsurface undergoes alternating intense shear and transient load variations, leading to localized dislocation accumulation and cracking, which suppresses the progression of continuous recrystallization. Full article