Search Results (3,648)

Conjugated polymers featuring donor–acceptor (D-A) architectures have emerged as promising candidates for visible-light-driven hydrogen evolution, owing to their tunable optoelectronic properties. However, achieving high photocatalytic activity without noble-metal cocatalysts remains challenging. Herein, we report a series of D-A type conjugated polymers based on dibenzothiophene sulfone (BTDO) as an electron acceptor and 3,4-ethylenedioxythiophene (EDOT) as an electron donor, synthesized via Suzuki polycondensation. By optimizing the donor/acceptor feed ratio, the optimal copolymer, EDOT-BTDO-5, delivers a hydrogen evolution rate (HER) as high as 87.5 mmol h⁻¹ g⁻¹ was achieved under visible-light irradiation (λ > 420 nm) without any Pt cocatalyst. To further boost the charge separation efficiency, a thiophene π-bridge was introduced, yielding a D-A-π-A ternary copolymer, EDOT-BTDO-T, which exhibits a significantly enhanced HER of 103.45 mmol h⁻¹ g⁻¹, along with remarkable operational stability, retaining ~69% of its initial activity after 20 h of continuous illumination. Comprehensive characterization, including photoelectrochemical analysis and density functional theory (DFT) calculations, reveals that the incorporation of EDOT broadens the visible-light absorption range, while the thiophene π-bridge extends π-conjugation, and facilitates efficiency. This work demonstrates a molecular engineering strategy to construct high-performance, metal-free organic photocatalysts by tailoring D-A and D-A-π-A architectures, providing valuable insights for sustainable photochemical energy conversion. Full article

Glioblastoma (GBM) frequently recurs after temozolomide (TMZ) therapy and exhibits substantial redox plasticity. Our previous work showed that the effects of hydrogen peroxide (H₂O₂) vary with its level and between parental and TMZ-resistant GBM cells. Succinate dehydrogenase subunit D (SDHD), a membrane-anchoring component of mitochondrial complex II, is positioned at the interface of electron transport and redox homeostasis, but its regulation in GBM remains unclear. We therefore examined whether SDHD expression changes across distinct H₂O₂-responsive contexts involving aquaporins (AQPs) and AKT. TCGA transcriptomic analysis showed higher SDHD mRNA expression in WHO grade IV than in grade II/III gliomas, whereas paired primary/recurrent high-grade glioma samples showed heterogeneous SDHD changes at recurrence. TMZ reduced SDHD, and SDHD knockdown decreased intracellular reactive oxygen species. Combined redox perturbation reduced SDHD, whereas AKT inhibition restored SDHD expression. Under receptor-associated signaling conditions, EGFRvIII expression or CXCL12 stimulation increased measured H₂O₂ together with AQP3, AKT Ser473 phosphorylation, and SDHD. In TMZ-resistant cells, pharmacological perturbation of aquaporin-associated signaling decreased AQP9 together with AKT Ser473 phosphorylation and SDHD. An AQP3-targeting compound further reduced cell density when combined with TMZ. Together, these findings suggest that changes in SDHD expression are consistent with a compensatory redox response in GBM cells and that its regulation varies with the nature of H₂O₂-associated signaling during TMZ-related stress. Full article

Enhanced oil recovery (EOR) is a crucial technology for improving crude oil recovery; it extracts residual oil from reservoirs through chemical, physical, or biological methods, thereby further increasing recovery rates after secondary recovery. Biosurfactants, particularly lipopeptides, have become a research focus in the field of EOR due to their excellent properties. However, existing studies have mainly concentrated on their production and characterization, while systematic investigation into their deactivation mechanisms and stability limits remains lacking at the molecular level. This study integrates density functional theory (DFT), ab initio molecular dynamics (AIMD), and classical molecular dynamics (MD) simulations to systematically reveal the hydrolysis mechanisms and stability boundaries of lipopeptide model molecules under high-temperature and high-salinity reservoir conditions from a multiscale perspective. DFT calculations show significant differences in the energy barriers among different hydrolysis sites in lipopeptide molecules, with side-chain structure being a key factor influencing amide bond hydrolysis. Metal ions present in reservoir environments (Na⁺, K⁺, Ca²⁺, Mg²⁺), particularly divalent ones (Ca²⁺, Mg²⁺), can act as catalysts to reduce the hydrolysis energy barrier. Electronic structure analysis reveals that the catalytic effect originates from the polarization of the carbonyl oxygen by metal ions, weakening the covalent character of the C=O bond. AIMD simulations reveal that only Ca²⁺ can specifically activate the hydrolysis of lipopeptide molecules at certain distances (critical distance), while other cations (e.g., Mg²⁺, K⁺, Na⁺) do not exhibit similar catalytic activity. MD simulations further demonstrate that Ca²⁺ ion concentration and temperature are the dominant factors influencing Ca²⁺ permeation toward hydrolysis sites (limit distance), with other ions having a weaker effect. By systematically simulating lipopeptide behavior under varying temperature and ion concentration conditions, a catalytic hydrolysis criterion based on the effective distance of Ca²⁺ interaction (i.e., limit distance ≤ critical distance) is established through multiscale simulation, and the performance boundaries of its temperature and salt tolerance are preliminarily defined. This study provides a theoretical basis and quantitative design guidance for the applicability of lipopeptide-based biosurfactants in high-temperature and high-salinity reservoirs. Full article

Co-based oxides are commonly introduced into porous ceramic membranes to add catalytic activity, but their attachment at the atomic scale remains unclear. We examined a buried Co₃O₄/Al₂O₃ interface formed by sol–gel deposition and thermal conversion. Site-specific focused-ion-beam (FIB) lift-out, scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy (STEM-EDS), and high-resolution transmission electron microscopy (HRTEM) were used to access and characterize the interface. A Co-rich spinel-type domain with a (111) lattice spacing was observed next to Al₂O₃(012). The observations guided density functional theory (DFT) initial models. After structural relaxation, substrate-O-mediated Co-O contacts emerged from both starting geometries: the O-bridged-start model exhibited eight contacts across four Co sites, whereas the non-bridged-start model developed three contacts around one Co site. Around the Co-O-Al linkages, there is a clear manifertation of the interface polarization and charge redistribution, indicated by charge-density-difference and Bader analyses. In both models, projected density of states (PDOS) showed coupling between Co 3d and O 2p states, while integrated crystal orbital Hamilton population (ICOHP) analysis further indicated that O atoms retained Al-O bonds while forming occupied-state Co-O bonds. These results support a representative, laterally distributed Co-O-Al motif as an atomic-scale pathway for chemically attaching the functional oxide to porous alumina. Full article

Accurate estimation of uniaxial compressive strength (UCS) is essential in geotechnical engineering, but conventional UCS testing is destructive and time-consuming. This study investigates the effects of mild acid exposure and freeze–thaw (F–T) cycling on the relationships between P-wave velocity (Vp) and UCS, density (ρ) and UCS, and Vp and selected physical properties in Apulian dolostone. Thirty-four cylindrical specimens were tested, comprising ten untreated specimens, five specimens in each acid-treatment group (3, 7, and 28 days), five specimens subjected to 10 F–T cycles, and four specimens monitored progressively during F–T cycling. Chemical weathering was simulated by static immersion in sulfuric acid (initial pH ≈ 5) without solution renewal and pH adjustment. Measurements included Vp, density, UCS, apparent porosity, and water absorption, together with thin-section petrography using optical microscopy and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM–EDS), SEM morphology, and X-ray diffraction (XRD) mineralogical analysis (four thin sections per treatment group; one representative specimen per treatment for SEM and XRD). Under the investigated conditions, both weathering processes produced moderate changes in the physical, ultrasonic, and mechanical properties, accompanied by minor microstructural modifications but without detectable mineralogical phase changes. The treatments also modified the empirical relationships between Vp, UCS, and the measured physical properties. These findings indicate that weathering influences the reliability of Vp-based UCS estimation for Apulian dolostone under the investigated conditions and provide new insights into the early-stage deterioration of this material. Full article

Objective: To develop and characterize a particulate biomaterial composed of hydroxyapatite derived from salmon bone and bovine type I collagen (HAPS/COL), and to evaluate whether different inorganic–organic ratios influence its physicochemical properties. Materials & Methods: Biomaterials were produced using three HAPS/COL proportions (70/30, 80/20, and 90/10). Physicochemical characterization included pycnometry, X-ray diffraction (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX). Results: Pycnometry showed densities close to that of pure hydroxyapatite, with only slight decreases attributable to collagen content. SEM-EDX images showed comparable surface morphologies characterized by hydroxyapatite particulates surrounded by collagen fibers. Ca/P ratios were slightly higher than the stoichiometric value of hydroxyapatite. XRD confirmed hydroxyapatite as the dominant crystalline phase across all formulations, with no evidence of phase alteration. TGA revealed mass losses of 2.75%, 1.90%, and 1.60% for the 70/30, 80/20, and 90/10 mixtures, respectively, with consistent mass loss-to-collagen ratios of approximately 0.09 for the 70/30 and 80/20 formulations, confirming proportional organic phase degradation. Conclusions: The three HAPS/COL ratios produced biomaterials with highly similar physicochemical profiles, indicating that within the tested range, the proportion of hydroxyapatite and collagen does not substantially alter material structure, composition, or thermal behavior. These findings confirm the successful manufacture of a stable HAPS/COL blend, allowing the use of efficient quantities of collagen, thus minimizing the costs associated with its purchase. Full article

Titanium alloy Grade 5 (Ti6Al4V) is a widely used material for aerospace components and biomedical implants due to its excellent combination of strength, low density, corrosion resistance and biocompatibility. Additive manufacturing (AM) technologies, such as Laser Powder Bed Fusion (LPBF) and Electron Beam Melting (EBM), could contribute to the manufacturing of high-performance Ti6Al4V components with complex geometries at reduced waste material and costs, but require powders with controlled morphology and flowability. Plasma Spheroidization is a key process for producing spherical titanium alloy powders suitable for AM; however, Direct Current (DC) thermal plasma is generally optimized for fine particle sizes. This study investigated the spheroidization of irregular Ti6Al4V powders (45–106 µm) through the optimization of DC thermal plasma processing parameters with the aim of extending its applicability to coarser powders. Particular attention was dedicated to particle size classification before and after plasma treatment. Pre-treatment sieving was found to be the most effective strategy for enhancing spheroidization and powder quality, while post-treatment classification improved the homogeneity of the final product. The resulting products were characterized by X-ray diffraction, morphological analysis, and flowability testing. High circularity powders (>0.7) with improved flowability (<30 s/50 g) were successfully obtained. The results demonstrate the potential of DC thermal plasma processing for producing coarser Ti6Al4V powders suitable for AM applications. Full article

New titanium alloys for biomedical applications are being developed to avoid the use of aluminum and vanadium, which may raise concerns regarding their long-term biological effects. In this study, the effect of tantalum content on the microstructure, hardness and electrochemical behavior of Ti–Mo–Zr–xTa alloys (x = 5, 10 and 15 wt.%) obtained by vacuum arc melting (VAR) was investigated. Characterization included assessment of samples via optical microscopy, scanning electron microscopy (SEM) with energy-dispersive spectroscopy (EDS) analysis and X-ray diffraction (XRD). Mechanical response and corrosion resistance were assessed using Vickers microhardness and electrochemical tests in Ringer’s solution, respectively. The X-ray diffraction results indicated that the β phase was predominant in all three compositions. Furthermore, the increased tantalum content promotes the stability of this phase and reduces the α″ martensite contribution observed in alloys with lower tantalum content. The mean microhardness decreased as the tantalum content increased, although measurements showed less dispersion with increasing indentation load. All alloys exhibited passive behavior in Ringer’s solution, with the Ti–15Mo–7Zr–15Ta alloy showing the lowest corrosion current density and corrosion rate. Full article

Rigid carbon frameworks in organic semiconductors restrict the tunability of their electronic and spin properties. Peri-metalation of polyacenes with coinage metals, particularly gold and copper, offers a route to electronic regimes not attainable in conventional organic systems, yet navigating this hybrid space often requires exhaustive quantum chemical sampling. This study integrates density functional theory with a small-data scientific machine learning framework to show that global electronic trends, including bandgaps, ionization energies, and electron affinities, can be captured by minimalist, coordinate-free descriptors. The hybrid architecture combines an analytical baseline defined only by inverse ring size and Au/Cu counts with coordinate-free residual learning that utilizes discrete metal sequence and topology descriptors. The original 53-descriptor residual model offers a chemically comprehensive representation, whereas a reduced 4-descriptor model assesses the persistence of principal predictive trends following significant dimensionality reduction. By circumventing explicit atomic coordinates, geometric parameters, orbital energies, wavefunctions, and interaction energies as model inputs, both models successfully recover chemically meaningful electronic properties and trends across the polyacene series while remaining sensitive to subtle local sequence effects. Systematic model–DFT deviations serve as diagnostic indicators, revealing that Cu-rich extended acenes represent a regime where the learned size and composition scaling is quantitatively insufficient, thereby necessitating further electronic structure analysis. While gold metalation yields stable, predictable electronic structures, copper incorporation drives the system into “emergent” regimes characterized by extreme bandgap narrowing and near-degenerate singlet–triplet states. This work establishes a framework in which machine learning performance itself marks the boundary of simple chemical trends, offering a rational approach to the discovery of low-bandgap, spin-sensitive hybrid semiconductors. Full article

This paper presents a wearable soft strain sensor based on a commercially available conductive thermoplastic polyurethane (cTPU) 3D-printed as an auxetic soft metamaterial for human activity recognition. The growing demand for flexible and wearable electronics, driven by advances in artificial intelligence, highlights the importance of such sensors in healthcare, medical rehabilitation, soft robotics, and human–machine interfaces. The auxetic cTPU sensor was mechanically and electrically characterized through empirical measurements and validated against numerical simulations. A single sensor mounted on a knee brace was used to collect gait signals across four activities: running, walking, standing, and sitting. Two classification approaches were investigated. A Long Short-Term Memory (LSTM) network was trained directly on the raw time-series signal, with the best configuration achieving 96% accuracy using Relative Standard Deviation Normalization with 50 hidden units. Traditional machine learning models, namely Random Forest and XGBoost, were trained on 30 extracted time-domain and frequency-domain features per motion cycle, achieving 100% and 97.33% accuracy, respectively, under five-fold cross-validation. To enhance model transparency, explainability analysis using SHAP identified power spectral density and the first harmonic frequency as the most consistently influential features across both models, with dynamic activities driven by frequency characteristics and stationary activities distinguished by signal mean amplitude. The results demonstrate that auxetic cTPU soft strain sensors combined with machine learning and explainable artificial intelligence provide an accurate and interpretable solution for wearable human activity recognition, highlighting their potential for applications in robotics, healthcare, and human–robot interfaces. Full article

Carboxylate-ligand-based coordination polymers and metal complexes form structurally adaptable crystalline systems, spanning discrete complexes, one-dimensional chains, two-dimensional layers, three-dimensional frameworks, and MOF-like architectures. This adaptability arises from diverse carboxylate binding modes and metal coordination preferences; auxiliary N/O donors are included only when carboxylate coordination remains central. However, the increasing availability of structural and electronic descriptors has not always been matched by equally rigorous validation of structure–function relationships. Hirshfeld surface analysis, energy-framework analysis, density functional theory, adsorption simulation, molecular docking, and machine learning are descriptor-generating methods; neither a method nor its output alone establishes descriptor-guided design. This review critically examines carboxylate-based coordination systems from the perspective of descriptor-guided function-oriented design. We discuss ligand-level regulation, metal-center effects, dimensional evolution, and what supramolecular, electronic, adsorption-related, and biological descriptors can and cannot prove. Functional studies covering luminescence and sensing; catalysis, adsorption, and small-molecule transformations; and bioactivity are evaluated by evidence strength. A claim-centered Descriptor-to-Function Evidence Ladder distinguishes structure reporting, descriptive descriptor use, post hoc association, controlled comparative trends, mechanism-supported validation, and prospective experimental confirmation. It evaluates a specific descriptor–function relationship rather than overall paper quality. Future progress should rely on standardized reporting, comparative structural series, function-specific validation, and transferable descriptor–function relationships. Full article

This work investigates the development of multifunctional bioceramic composites based on hydroxyapatite reinforced with the lead-free piezoelectric phase sodium potassium niobate, Na_0.5K_0.5NbO₃. Hydroxyapatite powder was synthesized by aqueous precipitation and combined with sodium potassium niobate synthesized by solid-state reaction to produce bulk ceramics containing 0, 10, 20, and 30 wt.% sodium potassium niobate, consolidated by conventional sintering. The materials were characterized in terms of density, linear shrinkage, phase composition, microstructure, elemental composition, flexural strength, and antibacterial response. X-ray diffraction analysis confirmed the coexistence of hydroxyapatite and orthorhombic sodium potassium niobate, with the intensity of sodium potassium niobate-related reflections increasing with its content, together with minor secondary phases. Scanning electron microscopy revealed the progressive incorporation of sodium potassium niobate grains into the hydroxyapatite matrix and showed a strong dependence of porosity on sodium potassium niobate content. Flexural tests showed that intermediate sodium potassium niobate additions improved strength compared with monolithic hydroxyapatite, whereas highly porous compositions exhibited reduced mechanical performance. Agar-diffusion tests against representative Gram-positive and Gram-negative strains showed measurable inhibition zones, although the differences between pure hydroxyapatite and composites containing sodium potassium niobate were limited and species-dependent. Slight increases were observed for P. aeruginosa and S. aureus, whereas no appreciable changes were detected for the other strains. Therefore, these findings should be regarded as preliminary evidence of antibacterial response rather than as confirmation of an intrinsic antibacterial effect of sodium potassium niobate. Overall, the structural and mechanical results indicate that hydroxyapatite/sodium potassium niobate composites are promising lead-free candidates for the development of multifunctional bioceramics, while their antibacterial response requires further validation. Full article

Background and Objectives: Platelet-rich fibrin (PRF) has been widely investigated as a biological material to enhance healing after tooth extraction; however, its clinical effectiveness remains uncertain. This systematic review evaluates the available evidence on its effectiveness in post-extraction socket management. Materials and Methods: A literature search was conducted across eight electronic databases for English-language studies published between 2015 and 2025. Only randomized controlled trials, including parallel-group randomized trials and randomized split-mouth trials, involving PRF with a control group were considered. The methodological quality of the included studies was assessed using the Cochrane Risk of Bias tool (RoB 1). Due to substantial clinical heterogeneity in PRF preparation protocols, outcome measures, and follow-up periods, a narrative synthesis was performed instead of a meta-analysis. Results: A total of 174 records were identified, of which 9 studies met the inclusion criteria. The methodological quality of the studies included was evaluated to assess the risk of bias, in accordance with the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions. Overall, 394 patients underwent 817 tooth extractions: 414 sockets were treated with different types of PRF, 251 were left to heal after suturing, and 143 were filled with a hemostatic sponge prior to suturing. Conclusions: PRF demonstrated superior outcomes in soft tissue healing and radiographic new bone density, although no statistically significant differences were observed in other parameters. Therefore, the available evidence does not allow us to draw definitive conclusions regarding the clinical effectiveness of PRF for socket filling after tooth extraction. The literature indicates that it may promote soft and hard tissue healing and reduce pain, swelling, and the risk of alveolar osteitis; however, evidence regarding its therapeutic effect on alveolar socket healing remains contradictory. Full article

Uranium nitride (UN) is considered a promising candidate material for advanced nuclear fuels in Generation IV reactors due to its high thermal conductivity and excellent fission product retention capability. However, the surface corrosion behavior of UN in oxygen-containing environments severely limits its practical application. In this work, first-principles calculations based on density functional theory (DFT) were employed to systematically investigate the adsorption and dissociation behaviors of O₂ molecules and O atoms on the UN(100), (110), and (111) surfaces. The electronic structure mechanisms underlying the adsorption were elucidated through analysis of surface work function, projected density of states (PDOS), Bader charge, and charge density difference. The calculated results show that O₂ molecules undergo thermodynamically highly favorable dissociative chemisorption on all three UN surfaces at 0 K, with the O–O bond length stretched to 1.44–1.50 Å, characteristic of a peroxo-like (O₂²⁻) species, which is intermediate between the superoxide (O₂⁻, ~1.33 Å) and complete dissociation. The most stable adsorption configurations on each surface are: (100)-H site (−4.05 eV), (110)-B(2) site (−4.81 eV), and (111)-H site (−5.03 eV), with the adsorption strength governed by the surface coordination environment. The adsorption energies of O atoms (−4.5 to −8.2 eV) are significantly higher than those of O₂ molecules. The order of the most stable O atom adsorption sites is (110)-B(2) site (−8.22 eV) > (100)-H site (−6.97 eV) > (111)-T(U) site (−5.09 eV), which differs from that of O₂, revealing the efficient O atom trapping effect of the groove structure on the (110) surface. Electronic structure analysis indicates that upon O atom adsorption, the work functions of the (100) and (110) surfaces increase by 0.62 eV and 0.39 eV, respectively, while that of the (111) surface decreases by 0.57 eV, suggesting that the (111) surface is more susceptible to further oxidation. In terms of bonding mechanisms, the interaction between O and U is primarily dominated by p–d hybridization between O-2p and U-6d orbitals. The U-5f orbital participates indirectly through f–d coupling with U-6d, while direct p–f hybridization is enhanced in the case of isolated O atom adsorption. This study provides an atomic-scale theoretical basis for understanding the initial oxidation mechanism of UN surfaces and offers important guidance for the surface protection design of UN-based nuclear fuels. Full article

The increasing integration density of electronic packaging places growing demands on electrically insulating materials with improved heat dissipation. Here, molecular dynamics simulations were used to investigate randomly dispersed boron nitride nanosheet (BNNS)/epoxy composites and clarify how BNNS loading affects structure, thermal transport, and thermomechanical response under a fixed crosslinked network. Atomistic DGEBF–TETA epoxy models with a crosslinking degree of 35% were constructed with BNNS loadings of 12, 15, 18, and 21 wt.%. Thermal conductivity was calculated using non-equilibrium molecular dynamics, while density, mesh-derived void fraction, elastic moduli, volumetric thermal expansion, and vibrational density of states were analyzed to connect molecular structure with macroscopic properties. The average thermal conductivity increased monotonically with BNNS loading, reaching 0.53 W/(m·K) at 21 wt.%, approximately 119% higher than neat epoxy. This improvement cannot be explained by density alone. Although composite density increased with BNNS content, surface mesh analysis showed that BNNS incorporation also increased the void fraction relative to neat epoxy, indicating that global densification coexists with local disruption of polymer packing. Spatial analysis further suggested that higher BNNS loadings reduce nanosheet separation, providing qualitative structural information for interpreting the thermal conductivity trend. VDOS analysis showed that BNNS suppresses low-frequency collective motions (0–5 THz) while enhancing intermediate-frequency vibrational modes (5–20 THz), which qualitatively accompanies the loading-dependent thermal conductivity enhancement. Thermomechanical calculations showed an overall increase in Young’s modulus and a reduction in volumetric thermal expansion, whereas shear modulus was less sensitive to BNNS loading. These results indicate that BNNS/epoxy performance is associated with coupled changes in density, local packing disorder, nanosheet distribution, and vibrational response, providing molecular-level guidance for designing thermally conductive and electrically insulating epoxy composites. Full article