Search Results (1,458)

Foot-worn electromagnetic harvesters are driven by irregular rigid-body motion, while their response is limited by mechanical stroke, coil geometry, mounting direction, and the electrical interface. This paper presents a reproducible numerical design study of a finite-stroke magnetic quasi-zero-stiffness (QZS) moving-magnet harvester. Two public three-axis foot-IMU records are processed with stated gyroscope-bias estimation, six-axis attitude estimation, gravity removal, residual-offset correction, filtering, and angular-acceleration calculation. Three explicit axes are used in the design screen, and the selected candidate is then evaluated over a 62-direction spherical grid. Rigid-body angular-acceleration and centripetal terms are included for specified sensor-to-harvester offsets. Two normalized magnetic force laws are compared. The electrical model uses position-dependent flux linkage, explicit series connection and polarity of coil sections, winding-derived resistance, and a position-dependent electromagnetic reaction force. A fixed-seed random screen evaluates 720 geometry-constrained candidates. The highest-ranked nominal candidate is a 150 mm external foot-worn module with a 40.6 g moving mass, a 30 mm hard half-stroke, 1649 turns in two series sections, and a 25.27 mm coil outer diameter. Across 72 design-screen cases formed from 12 five-second windows, three mounting axes, and two magnetic laws, this candidate remained hard-stroke- and design-stroke-safe. Its conditional ideal load-side power had a 10th percentile of 1.38 mW and a median of 2.03 mW. In the 62-direction check, all 1488 cases remained hard-stroke-safe; two opposite directions each produced one design-stroke exceedance, with a maximum displacement of 24.15 mm. Re-ranking all 30 Stage-2 candidates under coupling and magnetic-stiffness changes retained the long geometry family, although a 30% coupling reduction changed the highest-ranked candidate from 600 to 632. Soft-stop sensitivity, equation-level consistency, and multi-case Runge–Kutta convergence are also reported. The results support finite-stroke design screening, but they do not constitute prototype, finite-element, or delivered-power validation. Full article

Green-synthesized Nd-doped (2%)-ZnO samples were produced using hydrothermal synthesis (HT) and freeze-drying (FT) procedures. A water extract from Vaccinium vitis-idaea leaves was used to modify the Nd-containing zinc acetate solution. The hydrothermal synthesis was carried out in an autoclave at 170 °C for 8 h. The lyophilization process was carried out for 20 h at 0.15 mbar and then for a further 4 h at 0.10 mbar and at a temperature of −100 °C. The final treatment after both these procedures was carried out at 400 °C for 2 h. Both synthesis methods produced mixtures of rugby-like and ridged ZnO particles. The FT particles possess smaller crystallites sizes (24 nm) and higher polarity (I002/I100) in comparison with the hydrothermally obtained particles. It was ascertained by EPR analyses that there was a higher concentration of oxygen-vacancies-related paramagnetic centers after freeze-drying synthesis (more intensive line at g = 2.000). The photocatalytic reaction rates of the freeze-dried samples toward Malachite Green dye discoloration were found to be higher than those of the HT samples. These rates were greatly affected by the smaller crystallites sizes, higher number of singly ionized oxygen vacancies in the crystal lattice and higher surface polarity. Full article

Electrodeposition of bismuth from an acidic nitrate solution on copper electrodes by use of the potentiostatic mode of electrodeposition has been investigated with the aim to define conditions for obtaining dendritic forms. Morphology and structure of Bi deposits produced at the different cathodic potentials were featured by techniques of scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS) and X-ray diffraction (XRD), and correlated with the polarization features. The Bi dendrites were formed starting from the plateau of the limiting diffusion current density, while granules were formed at the cathodic potential which preceded the plateau. The shape of dendrites changed from very compact, formed at the plateau, to highly branched, formed at cathodic potentials beyond the plateau of the limiting diffusion current density, where the current density continuously grew with the increase in the cathodic potential. Both granules and dendrites showed the forceful preferred orientation in the basal (003) crystal plane with the lowest surface energy. The performed morphological and structural analysis classified Bi into a group of so-called normal metals, characterized by high values of both the exchange current density and overpotential for hydrogen evolution reaction and by low melting points. Full article

During long-term service, asphalt pavements undergo environmental stress and ageing, which cause cracking, rutting, and other distresses and raise maintenance costs. Polyurethane (PU) has high mechanical strength, elastic recovery, and ageing resistance due to its unique molecular structure. As an asphalt modifier, PU has been reported to improve high-temperature stability, moisture resistance, and durability. However, PU and asphalt differ greatly in polarity, density, viscosity, and phase structure, and these differences often lead to segregation and phase separation. The prepolymer method can mitigate these compatibility limitations by adjusting molecular weight, terminal-group activity, and soft/hard segment ratio before dispersion, chain extension, crosslinking, and post-curing in asphalt, resulting in better compatibility and more controllable processing. This review discusses PU soft/hard segment structures, asphalt composition, prepolymer synthesis and curing, microstructural evolution, pavement performance, storage stability, and use in other systems to clarify modification mechanisms and potential applications. This critical review aims to clarify material–reaction–process–performance relationships within the prepolymer route, with scope limited to molecular design, preparation mechanisms, performance, storage stability, and representative engineering applications. Future work should consider real service conditions and build multiscale evaluation frameworks that jointly optimise prepolymer design, processing, storage stability, and pavement performance, helping translate laboratory findings into low-carbon, long-life road materials that can be produced at scale. Full article

Porous microspheres based on 1,4-(dimethacryloyloxymethyl)naphthalene (DMN) and trimethylolpropane trimethacrylate (TRIM) were obtained by suspension–emulsion polymerization in the presence of toluene as a porogenic diluent. The obtained copolymers were subsequently modified using tetrachloromethane in the presence of anhydrous AlCl₃ via a Friedel–Crafts-type reaction. The influence of monomer composition and post-polymerization modification on the porous structure parameters and thermal stability of the materials was investigated. The synthesized copolymers exhibited well-developed porous structures with surface areas ranging from 368 to 494 m²/g. Increasing the TRIM content resulted in higher crosslinking density, earlier phase separation during polymerization, and formation of a finer porous architecture characterized by increased surface area and lower pore diameters. Chemical modification caused moderate and composition-dependent changes in the porous structure while preserving the mesoporous character of the materials. The highly crosslinked copolymers demonstrated the greatest structural stability during modification. Thermogravimetric analysis performed in helium revealed high thermal resistance of both parent and modified copolymers. The degradation process proceeded in two main stages characteristic of highly crosslinked methacrylate networks. Increasing TRIM content improved resistance toward advanced thermal decomposition, increasing the T_50% values up to 415 °C. Post-polymerization modification slightly decreased the temperature of the second degradation stage, probably due to the introduction of thermally less stable chlorinated fragments, while simultaneously increasing char residue formation. The synthesized materials were also evaluated as stationary phases for gas chromatography. Owing to their high thermal stability and the presence of polar ester functionalities, the copolymers enabled efficient separation of aliphatic alcohols at elevated temperatures. The obtained results demonstrate that porous poly(DMN-co-TRIM) microspheres constitute promising thermally stable materials with tunable porous structure and potential applications in chromatographic separation techniques. Full article

Small-molecule α-dicarbonyl compounds (α-DCs), including glyoxal, methylglyoxal and diacetyl, are electrophilic compounds characterized by two adjacent carbonyls. These compounds ubiquitously occur in various foods and food–medicine homologous herbs, generated via the Maillard reaction, caramelization, lipid peroxidation, and enzymatic reactions during thermal treatment and storage. Upon oral intake, small-molecule α-DCs are rapidly absorbed into systemic circulation, triggering protein and DNA damage, as well as inflammation. They also serve as important precursors to derive other hazards, such as advanced glycosylation end products possessing carcinogenic and genotoxic properties. Small-molecule α-DCs and their derived harmful products accelerate the progression of multiple metabolic diseases, e.g., cancer and diabetes. However, their pathological processes remain poorly elucidated, necessitating highly sensitive and accurate analytical methods. This review also systematically summarizes and discusses the current analytical techniques targeting small-molecule α-DCs. Chromatography and chromatography–mass spectrometry are still frequently used techniques. Given the polarity and weak ultraviolet absorption of small-molecule α-DCs, tedious pretreatment is necessary yet time-consuming. Novel rapid detection techniques such as mass spectrometry probes and direct ionization mass spectrometry have been proposed in recent years. Even so, developing rapid, eco-friendly, highly sensitive and accurate analytical methods remains a key priority for future research. Full article

In this study, novel and stable cellulose-based oleogels with tunable rheological properties were successfully developed for lubrication applications via cross-linking reactions of epoxidized soybean oil (ESO), microcrystalline cellulose (MCC), and isocyanate. This cross-linking strategy not only overcomes the incompatibility issue arising from the polarity difference between MCC and ESO but also enables precise control over the oleogels’ rheological behavior by tailoring the cross-linking density. The resulting oleogels exhibit excellent thermal stability, with an initial decomposition temperature (T_5%) of approximately 300 °C. Furthermore, oxidation resistance is significantly enhanced with increasing cross-linking density, resulting in a substantial increase in the oxidation induction time (OIT) from 5 to 79 min at 210 °C. Rheological characterization reveals that the oleogels exhibit typical shear-thinning and thixotropic behavior. The plateau modulus ($G_N^0$) exhibits a positive correlation with cross-linking density, accompanied by a simultaneous improvement in structural recovery ability. Tribological tests show that the friction coefficient increases with the cross-linking degree, while four-ball tests indicate that the extreme-pressure load-carrying capacity is governed mainly by the nature of the base oil in addition to the cross-linking density of the gel network. This work provides a promising strategy for the development of high-performance and customizable bio-based lubricating materials. Full article

Plasma-catalytic ammonia synthesis can operate without high temperatures and pressures, and its performance is closely tied to discharge modes. However, research on its microscopic discharge mechanisms remains limited. A 2D fluid model incorporating plasma-activated heterogeneous reactions was developed to investigate voltage polarity effects on discharge dynamics in an N₂/H₂ planar dielectric barrier discharge (DBD) reactor with catalyst-coated barriers. Under both polarities, discharge starts as a gas-phase streamer at the catalyst apex due to local field enhancement and then evolves into a surface ionization wave (SIW) with an order-of-magnitude higher electron density. Positive voltage restricts the SIW to the catalyst surface, whereas negative voltage induces SIWs on both the upper bare dielectric and the catalyst, driven by distinct charge accumulation patterns. During the short discharge pulse, the gas phase primarily functions as a radical generator, while surface reactions dominate NH₃ synthesis. Because positive voltage effectively targets plasma energy to the catalyst surface, it yields a higher peak NH₃ density near the catalyst (2.85 × 10¹⁹ m⁻³) compared to negative polarity (8.10 × 10¹⁸ m⁻³). Full article

Dihydrocaffeic acid (DHCA) is a naturally occurring phenolic acid with recognized antioxidant and biological properties. However, its relatively high polarity limits its applicability in lipid-based systems. In this study, myrtenyl dihydrocaffeate was synthesized through lipase-catalyzed esterification of DHCA with myrtenol using immobilized Candida antarctica lipase B. The reaction conditions were optimized using response surface methodology based on a central composite design, yielding an experimental ester yield of 39.94 ± 1.16%. The synthesized ester was characterized by NMR spectroscopy and subsequently evaluated using a combination of experimental and in silico approaches. Antioxidant activity was determined by DPPH^• and ABTS^•+ radical scavenging assays, while oxidative stabilization of rapeseed oil was assessed by pressure differential scanning calorimetry (PDSC). Antimicrobial activity was evaluated using disk diffusion, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) assays. In silico studies included ADMET profiling, PASS bioactivity prediction, protein target prediction, and molecular docking. These computational analyses were used only as hypothesis-generating tools because the predicted protein targets had low target-probability scores and were not experimentally validated. Myrtenyl dihydrocaffeate retained substantial antioxidant activity and significantly improved the oxidative stability of rapeseed oil, exhibiting protection factors comparable to those of DHCA. The ester also demonstrated mild antimicrobial activity against selected Gram-positive bacteria. Overall, the results indicate that lipophilization of DHCA with myrtenol is an effective strategy for developing lipophilic antioxidant derivatives for lipid-based food, cosmetic, or topical formulations, while the predicted molecular targets require experimental validation. Full article

To address the insufficient visible-light absorption of Bi₄O₅Br₂ photocatalysts, first-principles density functional theory (DFT) calculations were employed to systematically investigate the effects of I doping at different concentrations (12.5%, 25%, 50%, 75%, 87.5%, and 100%) on the geometric structure, electronic structure, optical properties, and photocatalytic CO₂ reduction performance of Bi₄O₅Br₂. Formation energy calculations and Ab initio molecular dynamics (AIMD) simulations indicate that the I-doped systems possess good thermodynamic and kinetic stability. Geometric analysis shows that I doping leads to a gradual expansion of lattice parameters along the c-axis (from 14.80 Å to 15.16 Å), due to the larger ionic radius of I⁻ compared to Br⁻. Electronic structure results reveal that all doped systems remain indirect band gap semiconductors, with the band gap decreasing from 2.56 eV for the pristine system to 2.25 eV at 87.5% doping. This reduction is mainly attributed to the progressive substitution of Br 4p states by I 5p states near the valence band maximum, which modifies the valence band structure. Differential charge density analysis shows electron transfer from Bi to I, enhancing local polarization effects. Optical property calculations demonstrate a pronounced red shift in the absorption edge and significantly enhanced absorption intensity in the visible region after I doping. The real and imaginary parts of the dielectric function also exhibit red shifts and increased peak intensities in the low-energy region. Gibbs free energy analysis indicates that the Gibbs free energy for *COOH formation decreases from 2.83 eV in the pristine system to 2.68 eV after I doping, while the free energy of the *CO intermediate decreases from 1.28 eV to 0.98 eV, significantly improving the CO₂ reduction pathway. This study provides a theoretical basis for improving the optical response and the thermodynamics of the CO₂ reduction reaction through halogen substitution, suggesting a promising strategy for enhancing the photocatalytic potential of Bi₄O₅Br₂. Full article

This study provides a detailed assessment of the corrosion-inhibiting performance of a previously synthesized pyrazole derivative (R9) for mild steel, using both experimental and theoretical methods. Electrochemical measurements, including potentiodynamic polarization and electrochemical impedance spectroscopy, showed that R9 achieved a maximum inhibition efficiency of 81% at a concentration of 10⁻³ M in 1 M hydrochloric acid. This improvement was reflected in the marked decrease in corrosion current density from 604 to 94 µA·cm⁻². The inhibitor displayed mixed-type behavior, influencing both anodic and cathodic corrosion reactions. This was confirmed by the small shift in corrosion potential recorded with and without R9, along with the increase in polarization resistance and the enhanced protection of the steel surface. Inductively coupled plasma spectrometry was used to measure dissolved metal ions, while scanning electron microscopy combined with energy-dispersive X-ray spectroscopy confirmed the formation of an adsorbed protective film on the steel surface. These findings further supported the effectiveness of R9 and agreed well with the electrochemical results. In the theoretical part, quantum chemical calculations on the isolated inhibitor R9 and the Fe-R9 complex (density functional theory, molecular electrostatic potential, Fukui indices, and atomic charges) were coupled with molecular simulations based on both molecular dynamics and Monte Carlo methods to provide a comprehensive understanding of the corrosion inhibition mechanism. The findings from the electronic structure studies, active site predictions, and adsorption analyses demonstrated effective and stable complexation of the R9 molecule with the steel. The results revealed an excellent correlation between the experimental and theoretical methods employed, highlighting the significance and robustness of the present study. Full article

Sodium (Na) metal anodes suffer from poor processability, severe volume fluctuation, unstable interfacial chemistry, and uncontrolled dendrite growth during cycling, which significantly hinder their practical application. Herein, a Na/Na₂In composite foil is fabricated through an in situ spontaneous alloying reaction enabled by a simple rolling–folding process using Na and indium (In) foils as precursors. Structural characterizations confirm the complete conversion of metallic In into the Na₂In alloy phase, forming a continuous architecture with uniformly distributed Na₂In networks embedded within the Na matrix. Owing to the sodiophilic and mechanically robust Na₂In framework, the Na/Na₂In composite anode effectively regulates Na plating/stripping behavior and suppresses dendritic growth, thereby maintaining a dense and stable electrode morphology during repeated charge/discharge processes. As a result, the Na/Na₂In symmetric cell exhibits stable cycling for over 900 h at 0.5 mA cm⁻² and 1 mAh cm⁻² with low polarization hysteresis, whereas the pure Na counterpart fails after only 143 h. Moreover, full cells paired with NaFe_1/3Ni_1/3Mn_1/3O₂ cathodes deliver enhanced cycling stability, retaining 87% of the initial capacity after 100 cycles at 0.5 C, together with improved rate capability. This work demonstrates a scalable mechanical fabrication strategy for high-stability Na metal composite anodes and provides new insights into the practical development of high-energy-density Na metal batteries. Full article

Social media has emerged as a crucial environment for examining public sentiment during disasters, providing immediate insights into collective emotions and urgent expectations. This research examines the emotional reactions expressed on Turkish posts shared on the X platform (formerly Twitter) following the 6 February 2023 earthquake by employing an integrated method that combines topic modeling and topic-based sentiment analysis. Data were collected between 10 February 2023 and 28 February 2023. A large dataset consisting of 305,000 tweets was compiled, and 296,836 tweets remained for analysis after preprocessing and filtering procedures. Latent Dirichlet Allocation (LDA), enhanced with term frequency-inverse document frequency weighting and bigram extraction techniques, was applied to identify prominent themes, including rescue operations, appeals for assistance, communication about missing persons, and disaster management. The sentiment polarity within each topic was determined using a hybrid deep learning model incorporating Bidirectional Encoder Representations from Transformers (BERT) embeddings Convolutional Neural Networks (CNN), Bidirectional Long Short-Term Memory (BiLSTM) layers, and FastText representations. This model reached a classification accuracy of 94%, with F1-scores of 0.91 and 0.95, recall values of 0.90 and 0.96, and precision values of 0.92 and 0.95, achieving higher performance than the evaluated baseline models. The findings indicate that supportive, solidarity-oriented, and resilience-related communication patterns were among the most frequently observed positive sentiment expressions, whereas negative sentiments appeared more frequently in discussions regarding delays in aid delivery and perceived shortcomings in institutional response. This study presents a scalable and flexible framework for analyzing sentiment in Turkish-language crisis communication, providing insights that may support disaster response monitoring and decision-making processes as well as the development of systems for tracking public reactions in real time. Full article

A biological/synthetic hybrid graft copolymer was obtained by grafting poly(acrylic acid) (PAA, synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization) to amylopectin (AMP). The novel graft copolymer presents amphiphilic properties due to the inherent insolubility of AMP in water and was further utilized as a mediator for the synthesis of gold nanoparticles (AuNPs) following an environmentally friendly in situ procedure. The AMP-g-PAA copolymer formation by the interaction of the PAA end groups with the C(6)-OH groups on an AMP backbone was confirmed by Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) and 1D (proton (¹H NMR) and carbon (¹³C NMR) nuclear magnetic resonance, and Distortionless Enhancement by Polarization Transfer (DEPT)) and 2D (correlation (COSY) and heteronuclear single quantum coherence (HSQC)) spectroscopies. The calculated degree of substitution of 1.17 suggests that the grafting was done at one OH from the three in an anhydroglycosidic unit (AGU) (preferably at that in C6 position), with a mean grafting efficiency of 76%. Additional information obtained using thermogravimetric analysis shows that the thermal decomposition of AMP-g-PAA occurs in two steps, with a residual mass of ~16 wt% at 700 °C, higher than AMP or PAA, indicating increased thermal stability of the copolymer. Dynamic and electrophoretic light scattering (DLS and ELS) measurements were used to determine the hydrodynamic size and ionic charge of the AMP-g-PAA self-assemblies in aqueous solution as well as their stability. The AMP-g-PAA was subsequently tested as a reducing agent in the environmentally friendly synthesis of AuNPs in aqueous solution, at different incubation temperatures, reaction duration, and inorganic/polymer weight ratios. The development of the surface plasmon resonance band of AuNPs, observed in UV–vis spectra, was consistently monitored over the reaction time. DLS analysis indicated time-dependent changes in the AuNPs’ particle size distributions, while scanning transmission electron microscopy confirmed that the AuNPs formed at the inorganic/polymer weight ratio of 0.36 and at 60 °C were predominantly well-dispersed, spherical-shaped nanoparticles. The AuNPs synthesized in situ within the copolymer matrix did not introduce additional cytotoxicity compared to the parent copolymer alone, with the composites representing a promising safety baseline for further investigation in biomedical applications. Full article

Hypersonic air-breathing propulsion via the Oblique Detonation Wave Engine (ODWE) offers superior thermodynamic efficiency compared to conventional scramjets by utilizing a stationary oblique detonation wave (ODW). While fundamental research has predominantly focused on two-dimensional planar wedges, realistic applications feature axisymmetric conical configurations. Over a cone, radial Taylor–Maccoll (TM) compression decelerates the flow and, in the mixed flow regime, establishes a localized subsonic pocket near the cone surface. However, the unsteady structures, triple-point kinetics, and cellular evolution under the competing influences of stabilizing TM compression and destabilizing Prandtl–Meyer (PM) expansions induced by a finite-length cone remain poorly understood. To address this gap, high-resolution numerical simulations of axisymmetric conical ODWs on a finite cone (semi-cone angle θ = 49°) were conducted at an inflow Mach number of Ma₀ = 7.5 using OpenFOAM. The methodology solves the reactive Euler equations coupled with a single-step Arrhenius model and three levels of adaptive mesh refinement to resolve fine-scale wave structures. Numerical results reveal that the localized subsonic pocket completely obliterates the smooth ZND-like initiation zone typical of purely supersonic configurations. Within this subsonic channel, acoustic disturbances propagate upstream against the bulk flow at a relative velocity of c − u, bypassing the supersonic wave-blocking effect to continuously impinge upon the detonation front. This acoustic feedback loop disrupts shock–reaction coupling, accelerating wave front bifurcation into single triple-point, dual triple-point, and PM-affected segments. Shock polar analysis validates that upstream-facing triple points exhibit greater shock strength, driving slow upstream migration and causing adjacent triple points to collide and reform into distinct, chaotic cell morphologies. Trajectory tracking confirms that the mixed flow cells are substantially larger and more chaotic than supersonic cases, directly reflecting amplified perturbations from the subsonic pockets. These insights provide crucial design criteria for optimizing cone angles to suppress irregular modes and stabilize conical ODWs. Full article