Latest Publications

Abstract:
This paper proposes a novel velocity estimation technique and integrates it with the particle filter to achieve precise positioning of an object moving within a magnetic anomaly field. To estimate the position in GNSS-denied environments, acceleration measurements acquired from the inertial measurement unit are combined with magnetic field measurements and a magnetic anomaly map. The magnetic field measurements are utilized at two levels. First, Bayesian data fusion is applied to process the rate of change of the magnetic field along the object’s trajectory in order to refine the velocity acquired from the inertial measurement unit. This refined velocity estimation serves as an input for the propagation model of the particle filter, which subsequently uses the magnetic field measurement and the magnetic anomaly map to estimate the object’s position. The proposed method was tested for navigating an unmanned aerial vehicle (UAV) using the ArduPilot simulator across a variety of realistic scenarios. The results demonstrate the efficacy of Bayesian-based velocity estimation in enhancing the classical particle filter approach, leading to a substantial reduction in the mean trajectory error. The developed method improves GNSS-independent positioning and navigation and holds promise for applications in various aircraft and robotic systems.

Keywords:
Magnetic anomaly navigation, Particle Filter, Bayesian inference, Unmanned aerial vehicle, Sensor fusion

Abstract:
Mode decomposition is a widely adopted data-driven strategy in modal analysis. It is an essential tool for identifying modal parameters and understanding the dynamic behavior of systems. However, existing mode decomposition methods often suffer from modal aliasing and lack clear physical interpretability. This study introduces a time-domain constrained mode decomposition method that employs a linear combination of free response signals to extract clean intrinsic mode functions and accurate modal parameters. A constraint matrix, derived from the autoregressive model of single-mode signals, is used to form a characteristic constraint equation and determine the decomposition coefficients. The influence of the autoregressive calculation time interval on the stability of Prony polynomial solutions is analyzed to determine the order and form of the constraint filter. Furthermore, combining the constraint filter with a low-pass FIR filter improves the noise robustness of the proposed method. For modal identification, the preliminary eigenvalues are determined using the Yule-Walker equation, followed by iterative elimination of spurious eigenvalues and refinement through the application of multi-objective constraint filters. Ultimately, the proposed method enables accurate, adaptive, and physically interpretable signal decomposition and modal parameter identification. Statistical results from numerical simulations validate its robustness to noise and stability, while comparisons with other mode decomposition techniques confirm that it achieves complete signal decomposition. Experimental verification using a frame test model further demonstrates the accuracy of the proposed method in modal identification.

Keywords:
Mode decomposition, Autoregressive model, Modal identification, Signal processing, Constraint filter

Abstract:
Molten carbonate electrolysis (MCE) is a promising high-temperature route to upgrade CO2-rich biogas into a higher heating value fuel while enabling CO2 separation and utilization. This paper proposes and experimentally evaluates a biogas upgrading concept based on a three-cell MCE stack operated on synthetic biogas mixtures. The stack is fed with CH4/CO2/H2O at the cathode and air at the anode and powered by external electricity, representative of surplus renewable power. Electrochemical performance is assessed through current-voltage characteristics and steady-state operation at selected current densities, while product-gas compositions are quantified by gas chromatography. The results demonstrate stable stack operation on biogas-type feeds and show that MCE can simultaneously remove CO2 and enrich the cathodic stream in H2 (and CO), thereby increasing the lower heating value compared with the raw biogas. From the measured data, key process indicators such as CO2 removal degree, gas upgrading factor, and specific electrical energy consumption are derived and discussed. The study establishes molten carbonate electrolysis as a viable and flexible option for biogas upgrading and valorization, particularly in systems coupled to intermittent renewable electricity. Unlike conventional separation-based routes (water scrubbing, PSA, membranes) that vent the captured CO2, or SOE-based power-to-methane systems that require a separate methanation reactor, MCE simultaneously removes CO2 and generates H2/CO within a single high-temperature unit. The present results provide the first experimental evidence that a multi-cell MCE stack can serve as a viable and load-flexible pathway for biogas upgrading and valorization, particularly when coupled with intermittent renewable electricity.

Keywords:
Molten carbonate electrolysis, Biogas upgrading, CO2 separation, High-temperature electrochemical conversion, Syngas and hydrogen enrichment

Abstract:
β-sitosterol is the most abundant phytosterol, but it exhibits low stability and bioaccessibility, requiring effective delivery systems. In this study, nine β-sitosterol-loaded microspheres were produced using edible insect proteins (T. molitor, A. domesticus, L. migratoria) and κ-, ι-, or λ-carrageenan via complex coacervation and spray-drying. The resulting spherical microcapsules (<15 μm) showed strong protein-polysaccharide interactions, particularly with κ- and ι-carrageenan, which induced β-sheet-rich structures and improved stability. λ-carrageenan produced more flexible, α-helical microspheres with lower oxidative stability. Lipid peroxidation was inhibited by up to 95%, although λ-CG variants exhibited 2–3× higher oxidation. HS-SPME/GC–MS confirmed the suppression of volatile oxidation markers. β-sitosterol retention reached 66–95%, largely depending on carrageenan type. In vitro digestion showed low oral (9–15%) and moderate gastric release (28–39%), with the highest release in the intestinal phase (38–54%), resulting in overall bioaccessibility exceeding 85% for all formulations.

Keywords:
Edible insect protein, Carrageenans, β-Sitosterol, Microencapsulation, Oxidative stability, Bioaccessibility

Abstract:
Discontinuous plastic flow (DPF) in austenitic stainless steels at cryogenic temperatures is typically identified by serrated stress–strain responses. Here, acoustic emission (AE) is used to probe deformation during uniaxial tensile tests of 304, 316L, and N50 steels at 4 K. Pronounced AE activity is detected well before stress drops, revealing discrete precursor events. The results show that DPF is preceded by progressive microstructural reorganization and establish AE as a sensitive tool for identifying plastic instability.

Abstract:
This paper investigates the dynamic behaviour of a thick Gao beam subjected to high-velocity inertial moving loads and substantial axial compressive forces. This approach addresses a significant gap by combining geometric nonlinearity, transverse shear deformation, and complete inertial effects (including Coriolis and centrifugal forces).
The mathematical model consists of two strongly coupled nonlinear hyperbolic partial differential equations, solved using the finite element method with space-time integration. Key findings include: (1) nonlinearity produces substantial geometric stiffening effects, with deflections decreasing by factors of 2-3 compared to linear models; (2) supercritical axial compression induces snap-through phenomena and bifurcation between equilibrium states; (3) under combined compression and moving loads, beam deflections are primarily governed by axial force magnitude rather than load weight, with multiple passages producing non-repeating response patterns; (4) maximum accelerations occur neither at mid-span nor at support entry, remaining relatively insensitive to transit velocity. The results indicate a strong detuning between the beam oscillations and the load transition cycles, especially at higher velocities. These findings have important implications for railway bridge design and structures experiencing simultaneous thermal stresses and dynamic vehicular loads, where simplified linear models may significantly underestimate dynamic effects.

Keywords:
Structural dynamics, Extended Gao beam, Moving mass, Inertial load, Non-linear dynamics, Shear deformation

Abstract:
This study investigatesd the hot stamping friction behaviour of TC4 aolly sheet using a self-developed high-temperature sheet tensile tribometer. The effects of contact pressure, lubrication (dry vs. Y₂O₃ powder), sheet temperature, and sliding speed on the coefficient of friction (COF) and wear mechanisms were evaluated. Increasing contact pressure induced a transition from ploughing to adhesion-dominated wear, raising the COF. Y₂O₃ powder lubricant formed a protective film that reduced the COF, though its effectiveness degrades under high pressure or low temperature. Elevating the sheet temperature decreased surface hardness and promoted adhesive wear, resulting in a more than 54% reduction in COF. Furthermore, an interactive multi-physics-based COF prediction model was developed, which captures friction evolutions under different conditions with high accuracy (prediction errors <6.8%). These findings provide insights for friction control in the hot stamping of titanium alloys.

Keywords:
TC4, Hot stamping process, Friction, Wear, Modelling

Abstract:
Fixed orthodontic appliances facilitate bacterial accumulation on brackets and wires, increasing the risk of enamel demineralization and periodontal inflammation. To address this challenge, near-infrared (NIR) responsive nanofibrous mats were developed for on-demand antibacterial disinfection of orthodontic brackets by incorporating cuttlefish ink-derived melanin nanoparticles (MNPs) into a poly(vinyl alcohol)/poly(ethylene oxide) (PVA/PEO) matrix. The incorporation of MNPs improved physicochemical properties, including enhanced thermal stability (∼77 °C increase in decomposition temperature), increased swelling capacity (∼2-fold compared with melanin-free fibers), and improved wettability. After thermal cross-linking, the fibrous network remained structurally stable in aqueous conditions with morphology preserved for up to 1 month and low melanin loss. Strong antioxidant performance was observed, reaching ∼60% 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging after 10 h. In vitro evaluation using L929 fibroblasts confirmed good cytocompatibility, supporting adhesion, viability, and proliferation. Under NIR irradiation at 808 nm (1.5 W/cm2, 10 min), efficient photothermal heating was achieved under wet conditions (∼55–60 °C) with stable performance across repeated cycles. Antibacterial efficacy was demonstrated, reducing Escherichia coli survival to 0.55% and disinfecting bacteria-contaminated bracket surfaces, while only minor inhibition of Lactobacillus acidophilus was detected. Overall, a biocompatible, marine-derived, and sustainable nanofibrous mat are presented for on-demand orthodontic disinfection.

Keywords:
cuttlefish ink, melanin nanoparticles, nanofibrous mats, photothermal, antibacterial, orthodontic braces

Keywords:
Magnesium alloys, Plastic deformation, Slip, Twinning, Stored energy

Abstract:
Nickel–titanium (NiTi) shape memory alloys (SMAs) with a nominal composition of 50.8 at% Ni and 49.2 at% Ti were fabricated using the as-fabricated laser powder bed fusion (LPBF) technique. This study focuses on the impact of post-processing heat treatments—specifically solution annealing and aging at 500 °C for 1 and 20 h—on phase transformation behavior and functional performance. Phase analysis (XRD) was conducted at room temperature (~ 25 °C), while uniaxial tensile testing was performed at both room (~ 25 °C) and sub-zero (–20 °C) temperatures. Differential scanning calorimetry (DSC) was carried out over a wide temperature range to evaluate the thermal behavior of the material. The results indicate that heat treatment conditions significantly affect transformation temperatures, phase constitution, and mechanical response. Depending on the treatment and test temperature, the microstructure varied from fully austenitic to fully martensitic or mixed-phase states. These variations manifested as distinct features in the stress–strain behavior, particularly in terms of martensitic transformation and superelasticity. The study demonstrates the feasibility of fine-tuning functional properties in LPBF-produced NiTi SMAs through optimized thermal processing strategies.

Abstract:
The design and optimisation of electrode and electrolyte materials to tune the properties of capacitors is a complex task with often unexpected outcomes. In this work, we assessed the electrochemical performance of a new carbon material, Graphene MesoSponge® (GMS), in combination with a flexible electrolyte, ionogel built from polyvinylalcohol polymer matrix and ionic liquid (IL) with ethylmethylimidazolium cations and bisulfate anions. From the electrochemical characterisations employing cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge-discharge, we established the superior performance of GMS compared to the activated carbon reference material. To gain insights into the unique chemistry of GMS structure and composition that lead to favourable electrochemical properties, we conducted density functional theory (DFT) simulations to examine the interactions of IL with the GMS material using nanoscale, periodic models of the pristine and two different defect site-containing graphene sheets. The dominant interactions in these systems are a network of H-bonds and dispersive interactions, similar in both systems, but favouring curved graphene due to its structural complementarity with IL ions. Changes to the electron density distributions relative to those of the separate components and the superimposed effect of cations/anions and polymer matrix interactions were used as the atomic-scale measure of surface wettability.

Abstract:
The rise in global carbon dioxide levels necessitates efficient, low-pollution energy technologies. Solid Oxide Fuel Cells (SOFCs) are promising energy converters, and their electrical performance is strongly influenced by the electrode microstructure. This study presents a comprehensive multiscale, experimentally grounded optimization pipeline for SOFC electrodes to maximize the electrical power density, integrating microscale and macroscale approaches. The methodology combines tomography-based microstructure characterization, computational homogenization, multiphysics simulations, model order reduction, and machine-learning-based surrogate modeling. Anode samples with fine, medium, and coarse grain sizes are analyzed using high-dimensional morphological descriptors to characterize microstructure morphology. Partial least squares discriminant analysis reduces the descriptor space to enable efficient surrogate modeling and generation of artificial microstructures by interpolation in the reduced space. Effective conductivities and permeability are computed by first-order homogenization and incorporated into a macroscopic fuel cell model to predict the power density. The proposed framework links microstructural information to macroscopic electrical performance within a nested optimization loop, enabling systematic exploration of physically realistic microstructural variants. Using a Ni-YSZ anode as a case study, the approach identifies the most suitable microstructure characteristics within an experimentally limited design space and provides a flexible optimization framework that can be adapted to different databases, models, and objective functions.

Keywords:
Optimization pipeline, Solid oxide fuel cells, Electrode microstructure, Multiscale modeling, Multiphysics modeling, Surrogate modeling

Abstract:
A comprehensive finite element-meshfree multiscale numerical framework is developed to investigate the size-dependent nonlinear asymmetric instability behavior of carbon nanofiber (CNF)-silicon carbide (SiC) nano-particle hybrid reinforced micro-arches subjected to radial concentrated loads applied at different positions. At the nanoscale, a finite-element-based homogenization strategy employing 3D periodic representative volume elements (RVEs) is developed to compute the effective elastic properties of nanocomposites reinforced with SiC nanoparticles and cylindrical CNFs, accounting for interphase characteristics. These homogenized material constants are subsequently incorporated into a nonlocal strain gradient theory (NSGT)-based radial point interpolation meshfree formulation, enhanced with an adaptive background decomposition integration approach to capture load location-sensitive nonlinear stability responses accurately. Numerical results demonstrate a pronounced multiscale coupling effect: increasing the CNF volume fraction from 1% to 4% results in approxi-
mately a 52% enhancement in all critical limit point loads, while increasing the SiC nanoparticle content from 1% to 5% increases them by nearly 29%. The relative interphase thickness provides a moderate gain of approximately 4.8%, and increasing the CNF aspect ratio strengthens the instability resistance by about 12.8%.
Conversely, increasing the SiC nanoparticle diameter results in a nearly 10.9% reduction in load-carrying capacity, indicating the superior reinforcing efficiency of smaller nanoparticles at a fixed volume fraction. Overall, the proposed framework successfully captures the highly nonlinear, curvature-sensitive, and size-dependent
instability characteristics of hybrid CNF-SiC micro-arches, offering a powerful predictive tool for the optimal design of advanced micro-scale structural components

Keywords:
Nonlinear stability, Meshfree approach, Size dependency, Finite element method, Hybrid composites

Abstract:
Low early-age strength is a significant barrier to the widespread use of multi-component cements with a low clinker factor in the construction materials industry. The low reactivity of supplementary cementitious materials used to replace Portland cement in mortar and concrete formulations is a primary factor contributing to inadequate early-age performance. This study investigates the reactivity enhancement of stockpiled granulated blast furnace slag (BS) through power ultrasound treatment (PUS) during mortar preparation. Reactivity was assessed using the Strength Activity Index (SAI), modified Chapelle test, and R3 heat release calorimetry. A custom-designed sonoreactor equipped with closed-circuit cooling was used to examine the effects of pulsed-mode PUS exposure on the consistency of fresh mortar and the mechanical properties of hardened specimens. Experimental investigations were conducted on mortar mixtures with a water-to-binder ratio of 0.5, in which BS replaced 20% of the cement by mass. PUS led to a 58% increase in early-age compressive strength; optimal results were achieved at 10 min. The influence of sonication duration, BS incorporation, and addition of a high-range water reducer on both early- and late-age strength development is systematically evaluated. The observed effects are explained by substantially increased reactivity, as evidenced by elevated heat release, and substantially enhanced dissolution of calcium, magnesium, and alkali metals from slag due to sonication.

Keywords:
Power ultrasound treatment, Granulated blast furnace slag, Early strength development, Portland cement, Cement-based composites

Abstract:
Increasing mechanical performance through fabrication advancements is a cornerstone of materials science. In this work, a nanometric protective Ni layer is applied to SiC reinforcement particles to enhance the wear resistance of co-electrodeposited metal matrix composites. The influence of this modification on the matrix-reinforcement interface is studied through electron microscopy and a novel micro-beam bending methodology. Direct micro-mechanical testing reveals a bonding paradox: the protective layer does not increase nominal interfacial strength, but increases wear resistance. The modification transforms the SiC reinforcement from insulators to surface-conductive particles, fundamentally altering the co-deposition mechanism. This leads to immediate particle encapsulation and a more homogeneous distribution of the reinforcement. Ultimately, protective layer suppresses interfacial porosity and ensures a continuous matrix-reinforcement contact resulting in higher wear resistance.

Keywords:
Metal-matrix composite, Interfacial bonding, Wear resistance, Co-electrodeposition

Abstract:
This work investigates experimentally and numerically the dynamics of rigid particles with two orthogonal symmetry planes settling under gravity in a highly viscous fluid at a Reynolds number much smaller than one. Joshi & Govindarajan (2025 Phys. Rev. Lett. 134(1), 014002), showed theoretically that for such shapes, the dynamics are qualitatively different for different signs of the product of two rotational–translational mobility coefficients, evaluated with respect to the particle centre of mass in a symmetric reference frame. However, upon examining a particle’s shape, it is not immediately evident if this product is negative, positive or zero. In this paper, we demonstrate how to estimate these coefficients and the sign of their product from experiments, using special initial orientations, and also numerically, based on the Stokes equations. Especially interesting are the ‘settlers’ – such particles that reorient and approach a stationary stable orientation, and we focus our study on this class of shapes. We show experimentally that cones, crescent moons, arrowheads and open flat rings are the settlers, and we evaluate from the experiments their rotational–translational mobility coefficients. Then, we reconstruct each experimental shape as a rigid conglomerate of many touching beads, and use the precise Hydromultipole code to calculate the mobility coefficients for the conglomerate. The numerical and experimental values are close enough to determine that the particles are the settlers, and to estimate the characteristic reorientation time scales. Our findings apply to non-Brownian micro-objects in water-based solutions – experimentally by the similarity principle and theoretically based on the Stokes equations. The reorientation of sedimenting rigid particles to a stationary stable configuration in a relatively short time might be used for environmental, biological, medical or industrial applications.

Keywords:
Stokesian dynamics, low-Reynolds-number flows, pattern formation

Abstract:
The limited lifetime of hot forging tools, caused by severe wear mechanisms such as abrasion, adhesion, thermal fatigue, and plastic deformation, remains a major challenge in forging operations. The study encompasses the entire process, from concept to industrial implementation. It begins with basic laboratory tests of the innovative material, followed by the application of protective coatings on an industrial scale to forging dies, which were then successfully used in production. The research presents the development and evaluation of novel hybrid surface treatments combining plasma nitriding with nanocomposite coatings based on tungsten boride alloyed with either tantalum (W-Ta-B) or titanium (W-Ti-B). The coatings were deposited using High Power Impulse Magnetron Sputtering (HiPIMS) from SPS-fabricated ternary targets. Laboratory characterization included structural, mechanical, tribological, and oxidation resistance analyses. The W-Ti-B films exhibited superhardness above 40 GPa and superior wear resistance, while the W-Ta-B coatings demonstrated enhanced oxidation resistance and adhesion. Both coatings revealed fine columnar microstructures and favorable H/E* and H³/E² ratios, indicating high resistance to plastic deformation and cracking. Industrial trials under hot forging conditions confirmed their effectiveness, with tool life extended by up to 80% compared with conventional nitrided tools. These findings demonstrate the strong potential of HiPIMS-deposited W-based boride coatings to significantly improve tool performance in demanding thermal and mechanical environments.

Keywords:
HiPIMS, Boride coatings, Hot forging tools, Nanocomposites, Durability

Abstract:
Rheumatoid arthritis (RA) remains a condition in which complementary, non-invasive assessment tools are actively explored. While previous thermography studies have focused mainly on temperature dynamics or
texture features, the diagnostic value of information-theoretic complexity measures is still not well understood. This study evaluates three such measures, Lempel–Ziv complexity (LZC), permutation complexity (PC), and
belief permutation entropy (BPE), for distinguishing RA patients from healthy individuals, with emphasis on the impact of different symbolic encoding strategies under no-cooling and cooling conditions. A dataset of 477 hand thermograms (291 healthy controls, 186 RA patients) was analyzed using four encoding schemes: binary, slope-direction, zero-crossing, and multilevel thresholding. All statistical conclusions were assessed at the
subject level using median aggregation per participant, with multiplicity-adjusted testing on protocol-matched cohorts to avoid within-subject dependence and availability bias. The primary endpoint was subject-level
discrimination quantified by effect size and ROC–AUC. Results indicate that the diagnostic utility of complexity measures in hand thermography strongly depends on both encoding choices and the acquisition protocol. Under
no-cooling conditions, several LZC variants and PC showed statistically significant but small group differences after BH-FDR correction (|

Keywords:
Rheumatoid arthritis, Infrared thermography, Information theory, Lempel–Ziv complexity, Permutation entropy, Belief permutation entropy, Symbolic encoding

Abstract:
A finite-strain identification framework based on the Virtual Fields Method (VFM) is proposed for the characterization of hyperelastic polymer materials subjected to heterogeneous deformation. The approach exploits full-field displacement measurements obtained by digital image correlation during physical experiments and formulates the inverse problem through the principle of virtual work. To enhance parameter sensitivity and identifiability, a T-shaped specimen together with a dedicated experimental setup was specifically designed to generate pronounced nonuniform strain fields from the onset of loading. The constitutive response is described within a finite deformation setting using hyperelastic strain-energy density functions, and the unknown material parameters are determined by direct inversion of the weak form of the equilibrium equations. A dedicated integration strategy based on Voronoi tessellation of the measurement points is developed to ensure consistent evaluation of the virtual work integrals. The proposed framework is assessed using both experimental data and synthetic data generated by nonlinear finite element simulations. The results demonstrate accurate and robust recovery of hyperelastic parameters, highlighting the effectiveness of the combined experimental–numerical approach and specimen design with an enhanced VFM formulation for reliable material characterization at finite strains.

Keywords:
Identification of material constants, Digital image correlation, Finite element analysis, Optimization, Hyperelasticity

Abstract:
Cartilage engineering is a new therapeutic approach in regenerative medicine. This study explored the chondrogenic potential of human dental pulp stem/stromal cells (hDPSCs) and adipose-derived stem/stromal cells (hAD-MSCs) grown on a hydrolytically modified poly(L-lactide-co-caprolactone) (PLCL) electrospun scaffold in relation to the phenotype of primary chondrocytes on PLCL. The effects of PLCL scaffold on the biological features of hDPSC, hAD-MSC, and their chondrogenic differentiation and chondrocytes biology were evaluated via flow cytometry, immunochemistry, biochemistry, and RT–PCR. The results demonstrated that PLCL supported hDPSC, hAD-MSC, and chondrocyte viability and cellular attachment. The chondrogenic potential of hDPSCs and hAD-MSCs on PLCL scaffold was evidenced by the mRNA expression of the cartilage-specific genes. Collagen type II (Col II) and aggrecan (Acan) gene expression and their proteins significantly increased in chondrogenically differentiated hDPSCs and hAD-MSCs on PLCL compared with undifferentiated stem/stromal cells on PLCL. The phenotype of differentiated hDPSCs and hAD-MSCs was comparable to primary chondrocytes grown on PLCL. The results of this study showed that PLCL scaffold promoted chondrogenic differentiation of hAD-MSCs and hDPSCs toward chondrocytes with phenotypic similarities to native chondrocytes. The PLCL scaffold composition has a positive effect on hDPSC, hAD-MSC, and chondrocyte behavior, chondrogenic gene expression, and matrix protein synthesis.

Keywords:
stem/stromal cells, hDPSCs, hAD-MSCs, chondrocytes, chondrogenesis, poly(L-lactide-co-caprolactone) (PLCL), cartilage engineering

Abstract:
This study advances beyond qualitative strength reduction trends in additive manufacturing fracture studies by establishing quantitative, configuration-based fracture assessment for Binder Jetting Additive Manufactured (BJ-AM) 17–4PH stainless steel with engineered surface cracks. Multiple crack geometries such as edge, inclined, single-corner, and double-corner configurations were precisely implanted in square (7 × 7 mm) and rectangular (3.5 × 14 mm) specimens with identical cross-sectional areas. Experimental investigations demonstrate that fracture resistance is governed by crack configuration and geometry-induced constraint, not crack area alone. Double-corner cracks retained 79–86% strength despite 25% crack area, while single-edge cracks exhibited 46–54% retention with only 20% crack area. Thickness-dependent constraint effects unique to BJ-AM geometries were quantified through comparative testing, revealing rectangular specimens (3.5 mm thickness) exhibit reduced constraint and lower fracture resistance than square specimens (7 mm thickness). J-integral governed elastic-plastic fracture assessment, validated through Extended Finite Element Method simulations predicting failure within ±10%, establishing predictive frameworks for defect-tolerant BJ-AM structural design.

Keywords:
Binder jetting additive manufacturing, Fracture toughness, J-integral, Extended finite element method, Surface cracks, 17–4PH stainless steel

Abstract:
This study presents the results of investigations on the influence of raw material type and synthesis method of cadmium yellow on the electrokinetic potential of pigment particles and the sedimentation stability of the resulting dispersions
in various chemical environments. Pigments were synthesized from cadmium salts (chloride, sulfate, nitrate, and carbonate) using sodium sulfide or elemental sulfur as sulfur sources. Two synthesis routes were applied: (1) precipitation of
the pigment from solution, followed by filtration, drying at 60 °C, and calcina-tion at 600 °C in acidic and alkaline media; and (2) direct reaction of cadmium carbonate with sulfur at 600 °C. The materials were characterized using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The zeta potential of
the particles was measured at different pH values, and dispersion stability was evaluated by turbidimetric analysis (Turbiscan). The obtained pigments were mixtures of compounds, with cadmium sulfide (CdS) being the predominant component. The chemical composition depended on the synthesis route and the
calcination process. A correlation was found between the electrokinetic potential,sedimentation stability, and chemical composition of the pigments. Calcination significantly affected surface properties, while the presence of chloride, sulfite,
sulfate, and carbonate species modified the electrokinetic potential. Acidic envi-ronments were found to enhance the sedimentation stability of cadmium-based pigments. The findings highlight the importance of synthesis conditions for the
surface chemistry, electrokinetic behavior, and sedimentation stability of cad-mium-based pigments in aqueous systems.

Abstract:
This study introduces a proof-of-concept methodology for evaluating pressure-dependent non-linear acous- tic properties of liver tissue. The proposed non-linearity index (NLI) is derived from echo amplitudes obtained at two substantially different acoustic pressures. Unlike previous harmonic-based approaches, the method relies solely on the fundamental frequency band, allowing clinical implementation without additional system mod-ifications. The image acquired for the lower pressure is then amplified to correct for the pressure difference between the beams. Next, the NLI is estimated as a ratio of local amplitudes of the amplified low-pressure
image (ALPI) to the high-pressure image (HPI). In the case of nonlinear media some energy of the wave is transferred from the pulse fundamental frequency to higher harmonics, which affects mainly the HPI. With the harmonics being filtered out from the signal, the HPI amplitude becomes lower than the ALPI amplitude.As a result, the NLI becomes higher than 1 and increases with the non-linearity of the imaged tissue. The
hydrophone measurements were compared to the simulation (k-Wave) of the ultrasonic field in water and veg-
etable oil. Next, we performed NLI imaging of healthy and fatty livers using SonixTouch (Ultrasonix) systems and two acoustic pressures of 390 kPa and 1590 kPa. Preliminary studies – imaging healthy and fatty livers using SonixTouch (Ultrasonix) systems were performed on the 4 livers of the authors of the article showed that for ‘healthy’ livers the NLI was below 1.1, while in one of the authors with previously diagnosed steatosis falling between score 1 and 2, the NLI locally exceeded 1.3.These results show that the obtained NLI values increase with the degree of steatosis, which agrees with theoretical expectations based on tissue B/A coefficients. The work emphasizes methodological feasibility and physical consistency rather than clinical validation, given the limited number of volunteers and ethical restrictions on patient recruitment.

Keywords:
ultrasound imaging, abdominal ultrasound

Abstract:
Ensuring effective protection for payloads during aerial operations—whether involving drones, helicopters, or airdropped objects—remains a critical challenge due to their widespread commercial and military use. This paper proposes an adaptable airbag-based protection system equipped with innovative semi-passive valve for controlled gas outflow. The introduced valve incorporates a custom-shaped shutter vent and, unlike typical kinematics-driven solutions such as metering pins, utilizes pressure-driven motion of a mobile valve’s piston during the landing process. The predesigned dynamics of the valve’s piston enables the required change in the shutter vent area, allowing precise outflow control and consequently ensuring desired force and deceleration profiles. Optimal valve design is achieved through a hybrid analytical–numerical method, iteratively alternating between an analytical system model and CFD simulations of gas outflow. It is demonstrated that the proposed adaptable system dissipates the entire impact energy and maintains protected object’s deceleration at almost constant level, achieving efficiency comparable to semi-active systems. As a result, it effectively minimizes overloads during emergency landings and increases safety of passengers and payloads.

Abstract:
In this review, a comprehensive analysis of aluminide coatings for nickel-based superalloys was performed with the particular emphasis on their processing, microstructural evolution, and performance under high-temperature conditions. Nickel-based superalloys are widely used in power engineering and aerospace industries; however, their susceptibility to oxidation and hot corrosion necessitates advanced surface protection strategies. Aluminide coatings offer effective protection through the formation of stable and adherent alumina scales. The review systematically evaluates major deposition techniques, including chemical vapour deposition (CVD), pack cementation, slurry aluminizing, and advanced hybrid methods, highlighting their influence on coating structure and properties. Special attention is given to the relationship between processing parameters, microstructure, and functional performance, including oxidation resistance, corrosion behaviour, and mechanical properties such as hardness and fatigue life.

Keywords:
aluminide coatings, nickel-based superalloys, chemical vapour deposition, pack cementation, slurry aluminizing, high-temperature oxidation

Abstract:
The oxygen evolution reaction (OER) using noble metal-based catalysts faced significant commercialization challenges due to the scarcity and substantial expense of these noble metals. Thus, the development of an efficient OER electrocatalyst for proton exchange membrane (PEM) water electrolyzers is still a challenging task. Herein, we present a facile approach to preparing cobalt phthalocyanine anchored on N-doped Co3O4 carbon network (Co3O4-NC) derived from metal organic framework (MOF). This strategy facilitates fast electron transfer and modulates the electronic structure. This improved electron transport induced by CoPc plays a significant role in enhancing OER, requiring only an overpotential of 1.2 V to deliver a current density of 1000 mA cm−2 with excellent stability. The Co3O4-NC2 Pc catalyst shows excellent durability during PEM water electrolysis and delivers industrially required current density of 1000 mA cm−2 at a potential of 1.66 V, outperforming commercial RuO2. The results of this research are twofold. Firstly, they promote green and low-carbon development. Secondly, they inject new vitality into the development of hydrogen energy technologies.

Keywords:
noble-metal free catalyst, oxygen evolution, phthalocyanine doped metal oxide, proton exchange membrane, water electrolysis

Abstract:
Present investigation systematically quantifies the role of interior defect morphology on tensile fracture behavior in Binder Jetting Additive Manufactured (BJAM) 17-4 PH stainless steel. Unlike prior investigations relying on stochastic natural defects, BJAM is uniquely employed to fabricate tensile specimens with five precisely controlled interior defect geometries such as spherical, disc-shaped, ellipsoidal, inclined ellipsoidal, and two-spherical at the mid-gauge location of round and square cross-sectional configurations. These artificial defects, occupying 16–35% of the gross cross-sectional area, serve as morphologically defined analogues of shrinkage porosities typical of conventional steel castings. A novel shape-independent empirical net section yielding method is developed that directly correlates projected defect area to fracture stress across all five defect geometries and both cross-sectional configurations. Results demonstrate that tensile strength reduction is governed by projected defect area independent of defect shape, with predictions falling within ±10% for the majority of configurations, providing a practically applicable fracture stress prediction tool for defect containing BJAM components. 3D finite element simulations coupled with a ductile damage model are implemented to accurately predict crack initiation sites and experimental load–displacement responses, achieving excellent agreement with experimental findings and providing independent computational validation of the empirical framework.

Keywords:
Binder jetting additive manufacturing, Ductile damage model, Interior defects, Shrinkage porosity, 17-4PH steel

Abstract:
In the present exploration, by unifying the simplified unit cell (SUC) micromechanical approach with the isogeometric numerical technique, a new solution model is developed to examine the small-scale dependent nonlinear stability feature of fuzzy fiber reinforced composite (FFRC) microplates under in-plane axial compression. A notable structural feature of this hybrid composite is the presence of uniformly aligned radially grown carbon nanotubes (CNTs) on the surfaces of the glass fibers, all of equal length, together with the interphase area between the nanotubes and the polymer material. Additionally, the interphase region between CNTs and the matrix is modeled as a distinct phase. To capture the influence of material microstructure, the effective elastic constants are first predicted using the SUC micromechanics model, while size-dependent effects are incorporated through the modified strain gradient theory. These material characteristics are then combined with an isogeometric plate formulation to enable accurate and efficient numerical analysis of FFRC microplates with different geometries and boundary conditions. The results show that the presence of CNTs as well as the interphase region significantly enhances both the buckling resistance and postbuckling stability through improving the stiffness and load transfer capability, particularly when the interphase becomes thicker or stiffer. The examination also highlights the influence of glass fiber volume fraction as well as the role of strain gradient tensors in enhancing the load-bearing capability. Overall, the proposed framework provides a consistent link between micromechanical design features and structural-scale stability performance of FFRC microstructures.

Keywords:
Micromechanical model, Fuzzy fiber-reinforced composite, Size dependency, Interphase region

Abstract:
Niobium nitride (δ-NbN) coatings were deposited on AISI 316L austenitic steel using reactive DC magnetron sputtering. This study investigates the effects of air oxidation on the surface morphology, topography, roughness, nanohardness, adhesion, and wear resistance of NbN coatings. Their microstructure and thickness were analyzed by scanning electron microscopy (SEM), while surface morphology and roughness were assessed using atomic force microscopy (AFM), and surface topography was assessed by an optical profilometer. Nanohardness was measured using a Berkovich indenter. Adhesion was evaluated via progressive-load scratch testing and Rockwell indentation (VDI 3198 standard). Wear resistance was assessed using the “ball-on-disk” method. Both as-deposited and oxidized NbN coatings improved the mechanical performance of the substrate surface. Air oxidation led to the formation of an orthorhombic Nb2O5 surface layer, which increased surface roughness and reduced hardness. However, the brittle oxide also contributed to a lower coefficient of friction. Despite reduced adhesion and increased surface development, the oxidized coating exhibited a significantly lower wear rate than the uncoated steel, though several times higher than that of the non-oxidized NbN. Considering its good wear and corrosion performance, along with the bioactivity confirmed in earlier research, the oxidized NbN coating can be considered a promising candidate for biomedical applications.

Keywords:
Nb2O5, NbN, magnetron sputtering, oxidation, adhesion, wear, surface engineering

Abstract:
Transition metal borides are attracting increasing interest due to their unique properties. They are not only characterised by very high hardness, but also considerable chemical and thermal stability. Silver, on the other hand, is a good material for increasing electrical and thermal conductivity, wear resistance and has antibacterial properties due to its biological characteristics. Combining these two materials can provide superhard bilayers with increased functional properties. In this study, it was decided to synthesise Ag/WB2.5, Ag/W0.76Ti0.24B2.5 coatings and compare their properties to the individual components. The silver coating was produced by pulsed laser deposition (PLD), while the WB2.5 and W0.76Ti0.24B2.5 coatings were formed by high-power pulsed magnetron sputtering (HiPIMS). To determine the mechanical properties, nanoindentation tests, adhesion of the coatings by scratch -test and wear resistance by abrasion in reciprocating motion were tested. In all cases, the silver film contributed to an increase in the wear resistance of the materials without major changes in the hardness results of the materials. In addition, the Ag/W0.76Ti0.24B2.5 film showed very good adhesion to the substrate. Human hand wiping simulator was also carried out using - Tribotouch. After 36 000 cycles Ag/W0.76Ti0.24B2.5 coating was slightly deformed, which was not visible macroscopically. This result is more than three times greater than for the pure silver film. It was also decided to carry out corrosion tests in an environment of 0.9% NaCl. The Ag/W0.76Ti0.24B2.5 bilayer has very good corrosion resistance, similar to pure silver.

Keywords:
Granular materials, Thermal, Electric, Discrete element method, Explicit time integration

Abstract:
A heavy-atom-free and non-toxic spirocyclic C-BODIPY singlet oxygen photosensitizer was successfully incorporated into electrospun polymeric nanofibers. Optimization of the material composition revealed that polycaprolactone (PCL), an FDA- and EMA-approved, biodegradable, easily accessible, and cost-efficient polymer, doped with BODIPY at a concentration of only 0.15 wt %, is an efficient photocatalyst for the degradation of the pharmaceutical agents ranitidine, propranolol, and cimetidine, selected as model water pollutants. The obtained nanofibers showed smooth and uniform morphology along with very high durability and resistance toward oxidation, remaining active even after 20 reaction cycles. EDX, ToF-SIMS and XPS analyses confirmed the homogenous distribution of BODIPY within the polymeric matrix. Furthermore, the materials showed significant photoinactivation of Staphylococcus aureus under white light irradiation compared to the control experiment performed without irradiation. These findings highlight the potential of the electrospun PCL nanofibers as optimal matrix for the immobilization with singlet oxygen photosensitizers and subsequent application in the decontamination of water from pollutants and pathogens.

Keywords:
antimicrobial photodynamic therapy, heavy-atom free photosensitizers, immobilization, polycaprolactone, singlet oxygen, water purification, BODIPY, electrospun nanofibers

Abstract:
Enhancing the stability and suppressing charge recombination in perovskite quantum dots in aqueous environment is a prerequisite for practical application in artificial photosynthesis. In this study, we confine CH3NH3PbBr3 (MAPs) perovskite nanocubes in the porous of zeolitic imidazole framework via a sequential trapping and growth activation strategy, resulting in composite photocatalyst for CO2 reduction to methane. The MAPs were in proximity with Co catalytic site in the ZIF, which facilitate rapid transfer of photogenerated electron from the MAPs to Co site with corresponding enhancement in photocatalytic CO2 reduction. The hybrid MAPs@ZIF show efficient photocatalytic CO2 reduction to Co with selectivity of 8.7% and CH4 with selectivity of 91.3%, which is far high than the photocatalytic activity for ZIF in the absence of PQDs. The DFT investigation revealed that the Co is the photocatalytic active site and the lowering of bandgap around the fermi energy level in the hybrid MAPs@ZIF compared to the individual components.

Abstract:
Laser-induced graphene (LIG) offers a promising platform for lithium-ion battery electrodes due to its high conductivity and porous three-dimensional architecture; however, its limited electrochemical activity restricts practical application. This study presents poly(3,4-ethylenedioxythiophene) -modified LIG cathodes prepared via two distinct polymerization strategies. In the first approach, 3,4-ethylenedioxythiophene monomers are polymerized in solution with an oxidant before deposition onto LIG. In the second approach, the monomer is first deposited onto the LIG surface, followed by separate oxidant introduction to confine polymerization directly at the electrode interface. Structural characterization confirms successful polymer incorporation while preserving the porous LIG framework. The surface-confined approach yields more uniform polymer distribution and stronger polymer-substrate interaction, as evidenced by enhanced π–π coupling observed in Raman spectra. Electrochemical evaluation reveals that polymer loading significantly affects performance, with an optimal monomer volume providing balanced coverage without pore blockage. Electrodes prepared via surface-confined polymerization deliver a specific capacity of approximately 170 mAh g−1 at 0.003 A g−1, representing a tenfold improvement over pristine LIG, and retain 85% capacity after 100 cycles. Electrochemical impedance spectroscopy confirms reduced charge-transfer resistance and improved ion diffusion for this approach. These findings establish poly(3,4-ethylenedioxythiophene) -modified LIG as a promising metal-free cathode material for flexible lithium-ion batteries.

Keywords:
Energy storage, Laser-induced graphene, Polymer coating, Plasma treatment, Lithium-ion battery

Abstract:
Ferritic–martensitic P91 steel is widely used in high-temperature power plant components due to its excellent creep resistance and mechanical stability. However, long-term service exposure and improper heat treatment can lead to progressive microstructural degradation, resulting in a reduction of mechanical properties and component lifetime. Reliable, non-destructive methods capable of detecting such microstructural changes are therefore essential for condition monitoring and life assessment. In this study, the influence of controlled heat treatment at temperatures ranging from 200 °C to 600 °C on the eddy current (EC) response of P91 steel was investigated. Eddy current measurements were performed over a range of probe operating frequencies, and changes in resistance and reactance components were quantitatively analyzed. The EC results were correlated with detailed microstructural observations, revealing a strong relationship between electromagnetic response and recovery and tempering phenomena, including dislocation density reduction, martensite lath degradation, and carbide coarsening. The findings demonstrate that eddy current testing is highly sensitive to thermally induced microstructural evolution in P91 steel and shows significant potential as a non-destructive tool for assessing thermal exposure and material degradation in power plant components.

Keywords:
Non-destructive testing, Power engineering steels, Eddy current, Coil impedance,

Abstract:
Developing thick and well-adhered high-entropy alloy (HEA) coatings remains a major technological challenge due to the high cost and complexity of existing deposition methods. This study introduces a novel hybrid approach that combines mechanical alloying, electrochemical co-deposition, and high-temperature annealing to fabricate CoCrFeMnNi-based coatings. In this process, HEA powders obtained by mechanical alloying are suspended in a classical Watts bath and co-electrodeposited with nickel onto copper and steel substrates. Subsequent annealing promoted homogenization and diffusion between the coating and substrate, producing coatings up to approximately 100 μm thick, although residual porosity remained an important issue requiring further optimization. Structural and chemical analyses revealed face-centered cubic solid solutions with good adhesion, as indicated by the absence of cracking and delamination during scratch testing, and a maximum hardness of 6.25 GPa. The use of co-electrodeposition enables easy incorporation of complex HEA compositions using conventional electrochemical equipment, drastically reducing the cost and process temperature compared with vapor- or laser-based methods. The developed technology not only overcomes the limitations of direct HEA electrodeposition but also allows the deposition of coatings on complex geometries using environmentally friendly aqueous electrolytes. This simple yet versatile approach opens new pathways for producing high-performance protective coatings for applications in energy, aerospace, and nuclear industries, where mechanical robustness and chemical stability at elevated temperatures are critical.

Abstract:
In the paper the theoretical modeling of ultrasonic testing of railway rails with high scanning speed is considered. The model for the calculation of the ultrasonic field generated by the ultrasonic transducers and the pulse echo amplitude received after wave reflection at the defect is developed. The model is based on well-established principles of elastodynamic theory: the Rayleigh–Sommerfeld integral, the Auld reciprocity relation, and the Kirchhoff approximation. It forms the basis for design of computer program to simulate ultrasonic inspections of railway rails with automated mobile systems. The major innovation introduced in the model is taking into account the high scanning speed of the ultrasonic probes over the rail head and the limited repetition rate of the ultrasonic system. The mentioned aspects of the high-speed rail testing require the revision of one of the basic paradigms of the current ultrasonic models, which assume that the scanning speed of the ultrasonic probe is negligible in comparison to the speed of ultrasonic waves propagating in the tested material. Actually, when scanning rails at a speed of 120 km/h, the ultrasonic probe can change its position up to 5 mm between transmitting and receiving ultrasonic pulses reflected from defects located in the rail foot. Such a shift in the probe position is not negligible and should be considered in calculations. As a consequence, the ultrasonic system’s slow repetition rate and fast scanning speed can make it less likely that certain rail flaws will be found. To quantitatively examine the severity of these phenomena, the new ultrasonic model and related simulation software was developed.

Keywords:
non-destructive testing, railway rails defects, testing of railway rails, automatic ultrasonic testing

Abstract:
The design of multifunctional hydrogel platforms with strong antibacterial and pro-healing activity is essential for next-generation wound dressings. In this work, a novel nanocomposite hydrogel was fabricated by grafting polyacrylamide onto xanthan gum, crosslinking with borax, incorporating Fe₃O₄ nanoparticles, and inducing in-situ growth of Cu-BTC MOF within the magnetic hydrogel matrix. This integrated structure represents an efficient innovation among MOF–hydrogel systems by combining the biocompatibility of XG, the functional network provided by PAAm, the magnetic features of Fe₃O₄, and the controlled Cu2+-based antibacterial activity of Cu-BTC. Characterization confirmed successful formation and stable polymer–MOF interactions, accompanied by favorable physicochemical properties including superparamagnetic behavior (saturation magnetization ∼8 emu/g), relatively high surface area (56.90 m2/g), and improved thermal stability. The biological assessments were assessed for wound-healing relevance. Swelling of the hydrogels was measured at different pH values (4.0, 5.5, 7.4) and in varying ionic strengths, showing the highest uptake for XG-grafted-PAAm, while Fe₃O₄ and Cu-BTC reduced swelling by increasing crosslinking, supporting moisture retention and compact structure in wound environments. Furthermore, the magnetic XG-grafted-PAAm @Cu-BTC nanocomposite showed antibacterial activity, with MIC/MBC values of 125/250 μg/mL against E. coli and 500/1000 μg/mL against S. aureus. Cytocompatibility testing revealed acceptable viability at low–moderate concentrations (91–54% at 1.9–15.6 μg/mL), while the scratch assay confirmed accelerated fibroblast migration at 3.9 μg/mL, indicating a pronounced pro-healing effect. Overall, the synergistic antibacterial action, controlled Cu2+ release, hydration capacity, and favorable cell-migration response position this MOF–magnetic hydrogel system as a promising candidate for advanced wound dressings.

Keywords:
MOF-based hydrogel, Antibacterial, Cu-BTC, Xanthan gum, Wound healing

Abstract:
Automated damage inspection of railway viaducts requires pixel-level identification of structural components and surface damage such as cracking and rebar exposure. A common assumption in bridge inspection is that damage segmentation improves when component information is provided alongside the image. This study tests that assumption on the Tokaido synthetic viaduct dataset using controlled comparisons between segmentation models with and without component information. Both damage and structural component segmentation are evaluated across multiple architectures, and the trained component model is assessed on real viaduct photographs against a baseline model requiring no task-specific training. Under the original random split, explicit component conditioning does not produce a measurable improvement in damage segmentation: all tested strategies remain within 0.008 mean Intersection-over-Union (mIoU) of a baseline without component input, and this null result persists even when component predictions are reliable. Under a leakage-controlled scene-disjoint split, however, the same component-aware variants show a small positive trend (up to +0.019 mIoU over three seeds), so the effect of component conditioning depends on the evaluation protocol. The best unconditioned model reaches 0.569 mIoU for damage segmentation; for real-photo component segmentation, the trained model reaches 0.424 mIoU compared with 0.250 mIoU for the training-free baseline. These results show that multitask benefits reported in bridge inspection do not automatically translate into gains from explicit use of component information on synthetic viaduct data, where damage occurs almost exclusively on columns yet is too sparse for structural element identity to yield more than a marginal localisation gain. The multi-architecture benchmark and the measured real-photo structural transfer gap provide reference baselines for subsequent work on component-aware and transfer-robust inspection.

Keywords:
semantic segmentation, viaduct inspection, bridge damage, CNN, Vision Transformer, component-aware segmentation, Tokaido dataset, GroundedSAM, synthetic- to-real transfer

Abstract:
The receptor-binding domain (RBD) of the SARS-CoV-2 spike protein is the main target of neutralizing antibodies (Abs) and nanobodies (Nbs). Although their binding affinities are well characterized, their mechanical stability under force remains poorly understood, despite its relevance in viral attachment, immune recognition, and receptor engagement. Here, we present a comparative nanomechanical analysis of three Abs (PDI-231, S2X259, and R1-32) and three Nbs (R14, C1, and n3113.1) bound to the RBD from the WT and Omicron variants BA.4 and JN.1. Using steered molecular dynamics within the Martini 3 coarse-grained framework, we identified distinct mechanical signatures determined by epitope topology, binding architecture, and variant-specific mutations. Ab/RBD complexes display asymmetric rupture events in which the heavy chain serves as the main pathway for force transmission, while the light chain provides secondary reinforcement. The cooperative action of both chains enhances mechanical resilience, supporting rupture forces near 500 pN. In contrast, Nb/RBD complexes exhibit rigid-body dissociation with direct force transmission through compact single-domain scaffolds and minimal structural deformation. Variant-dependent unfolding of RBD regions, particularly residues 438–507 and 516–529, appears as a recurrent fracture motif contributing to adaptive mechanical response. These results establish mechanical stability as a key descriptor of immune complex robustness, complementing thermodynamic affinity. By linking architecture, epitope geometry, and force propagation, this study provides a quantitative framework for designing antibodies and nanobodies with improved mechanical resilience against viral evolution.

Abstract:
Rubber derived from end-of-life tires offers a sustainable solution for reducing the environmental impact of cement-based materials. In this study, recycled rubber aggregate (RRA) was used as a partial volumetric replacement (15% and 30%) of natural fine sand in cement-based mortars to evaluate its effectiveness in mitigating alkali–silica reaction (ASR). The experimental program included mechanical testing, ASR expansion measurements, and microstructural analyses. The results showed that increasing RRA content led to a reduction in compressive strength by up to 24.1% and flexural strength by up to 19.8% after 28 days of curing. Despite this reduction, a significant improvement in ASR resistance was observed. For mortars containing highly reactive aggregates, ASR expansion decreased from approximately 0.73% in the reference mixture to 0.47% with 30% RRA, corresponding to a reduction of up to 33%. Microstructural observations confirmed that RRA acts as a stress-relieving inclusion, limiting crack propagation and reducing ASR gel formation. Physicochemical analyses (XRD, TGA, and FTIR) indicated that alkaline treatment induces surface oxidation of RRA without affecting the stability of mineral components. The findings demonstrate that ASR mitigation is not solely due to dilution of reactive aggregates, but also to the elastic and microstructural buffering effects of RRA. Furthermore, a simple predictive model is proposed to estimate the required rubber content for effective ASR mitigation.

Keywords:
Keywords Recycled rubber aggregate, Reactive aggregate, Flexural test, Compression tests, Microstructural analyses

Abstract:
Thermal residual stresses generated during the cooling of metal–ceramic
composites produced by powder metallurgy remain a critical challenge for ensuring their reliable performance. The objective of this paper is to present and assess a methodology for constructing a finite element model for determining thermal residual stresses in metal-ceramic composites using the microstructure of the composite obtained from X-ray microcomputed tomography (micro-XCT) images for the mesh creation. The effectiveness of the micro-XCT-based finite element model is validated through a case study of residual stress behavior observed in an alumina-chromium composite that was consolidated by hot pressing. The influence of the choice of material models for the matrix and reinforcement and of the type of finite elements on the accuracy of the numerical simulations is analyzed. A comparison between the computed residual stresses and neutron diffraction measurements demonstrates a correlation validating the modeling approach. Of all the factors considered in the micro-XCT-based finite element simulations such as mesh quality, constitutive models for phase materials and the temperature dependence of the coefficients of thermal expansion mesh quality had the greatest impact on the accuracy of the numerical results in comparison to the residual stress measurement data
obtained from neutron diffraction.

Keywords:
Finite element analysis, metal-ceramic composites, microcomputed X-ray tomography, size effect, thermal residual stress

Abstract:
Glass fiber/Elium acrylic thermoplastic laminate containing various weight fractions of multiwalled carbon nanotubes(Graphistrength MWCNTs) was subjected to tensile, low-velocity impact, and dielectric tests, and compared to a control compos-ite without MWCNTs. The composite materials were manufactured via vacuum resin infusion following manual preimpregna-tion of the reinforcement phase. The results showed that integrating from 1 to 2.5 weight fraction (wt%) of MWCNTs enhancedboth elastic properties and impact resistance. Specifically, the Young's modulus increased by more than 18% relative to thepristine composite. Under impact energies of 40 and 60 J, the MWCNT-reinforced composite exhibited a 15% increase in peakforce, a 16.4% reduction in absorbed energy, and a 30% enhancement in the penetration threshold. Improvement in mechanicalperformance could mainly be due to the good MWCNT–fibers–matrix adhesion which creates strong bonding between glassfibers and MWCNT, thereby improving stress transfer. Concurrently, the composite materials became electrically conductivestarting at 2 wt% of MWCNTs, suggesting a high probability of interconnected MWCNT particles and indicating the percolationthreshold. While 2 wt% can be considered as the optimal MWCNT content for overall properties, an exceptional 680% increase inelectrical conductivity was achieved at 3.5 wt%.

Keywords:
elastic properties, electrical conductivity, Graphistrength MWCNT, impact resistance, laminate composite

Abstract:
The development of advanced poly(vinyl alcohol) (PVA)-based biomedical materials is often hindered by the reliance on toxic chemicals and energy-intensive processes, raising sustainability and safety concerns. This work addresses these challenges by presenting a low-temperature, “green” approach for fabricating PVA-based nanofibrous hydrogels cross-linked with natural lemon juice (Citrus limon) and enriched with bromelain derived from pineapple (Ananas comosus) extract. Electrospun nanofibers containing fruit components were stabilized via mild thermal treatment at 60 °C, enabling covalent ester bond formation while avoiding harmful cross-linkers and preserving the enzymatic activity of bromelain. Analysis results confirmed the successful formation of hydrogel, its reduced solubility in aqueous environments, improved mechanical properties, and tunable pH-responsive swelling behavior. Bromelain incorporation altered cross-linking density, enhancing multifunctionality. The dual-bioactive hydrogel could release incorporated substances, demonstrating strong antioxidant capacity and antibacterial activity. Moreover, the developed nanofibrous hydrogel showed photothermal response under near-infrared (NIR) irradiation. In vitro assays using L929 fibroblasts demonstrated high biocompatibility and stimulated cell proliferation over extended culture periods. Moreover, the developed hydrogel supported early-stage wound closure, highlighting its importance in promoting the initial phases of the healing process, which are critical for effective tissue regeneration. By combining the natural bioactivities of lemon juice and bromelain with the structural advantages of electrospun PVA fibers, the developed nanoplatform offers a promising, environmentally friendly solution for advanced wound healing, bacterial elimination, and infection control applications.

Keywords:
“Green” cross-linking, Lemon juice, Pineapple-derived bromelain, Electrospun nanofibers, Antibacterial hydrogel

Abstract:
This study explores the development of porous poly(vinylidene luoride-co-hexafluoropropylene) based gel polymer electrolytes (GPEs) via a general polyethylene glycol extraction method, fol-lowed by the incorporation of perchlorate salts (LiClO4, Mg(ClO4)2, NaClO4). The influence of cation valency and ionic radius on ionic transport was systematically investigated for high-voltage supercapacitors (SCs). Among the prepared electrolytes, the LiClO4 based GPE exhibits the high-est ionic conductivity of 7.4 × 10−3 S cm−1 at room temperature along with a stable electrochemi-cal window of 2.6 V and superior performance in symmetric SCs. Symmetric SCs assembled with activated carbon achieved a specific capacitance of 76.7 F g−1 and retained excellent cycling sta-bility of 96.9% after 10 000 consecutive charge-discharge cycles measured at a current density of 1 A g−1. This work highlights the enhanced performance of ion transport attributed to a well-interconnected porous structure at the electrode−electrolyte interface and provides insights into the role of chemistry in high-performance SCs.

Keywords:
activated carbon, gel polymer electrolyte, ionic conductivity, supercapacitor, temperature dependence

Abstract:
One of the most promising green solutions to the growing need for renewable, environmentally friendly and not expensive energy sources, that can replace fossil fuels, is oxygen production during water electrolysis. The authors present gold and gold-semiconductor electrodes based on periodic self-assembled polystyrene spheres template for efficient oxygen evolution reaction (OER) via water splitting. The two-dimensional ordered Au crystal (OAuC) exhibits onset overpotential 1.63 V vs. RHE (reversible hydrogen electrode) with small Tafel slope of 76 mV dec−1 with excellent stability profile. The distinct ordered feature of the OAuC confers promising potential as electrocatalyst for OER.

Keywords:
Alkaline media, gold periodic electrodes, oxygen evolution reaction, water electrolysis

Abstract:
Current graph neural network (GNN) model-stealing methods rely heavily on queries to the victim model, assuming no hard query limits. However, in reality, the number of allowed queries can be severely limited. In this paper, we demonstrate how an adversary can extract a GNN with very limited interactions with the model. Our approach first enables the adversary to obtain the model backbone without making direct queries to the victim model and then to strategically utilize a fixed query limit to extract the most informative data. The experiments on eight real-world datasets demonstrate the effectiveness of the attack, even under a very restricted query limit and under defense against model extraction in place. Our findings underscore the need for robust defenses against GNN model extraction threats.

Keywords:
recycled materials, end-of-life tiers, rubber, fibres, concreto

Abstract:
Ultrasound (US) is a widely used imaging modality due to its availability, relatively low cost, and high frame rate. However, the quality of US images is usually considered inferior compared to other modalities, which can make image interpretation and the development of computer-aided diagnostic systems more challenging. In this work, we propose a deep reinforcement learning approach for US image denoising. Our method employs a software agent that learns to select both the location and types of interpretable image processing filters to apply. We demonstrate that the agent effectively reduces speckle noise in homogeneous regions while preserving or enhancing the structural details at the boundaries between such regions. Compared to other deep learning methods, our approach is based on well-known and simple filtering operations, making the denoising process more transparent and easier to interpret.

Keywords:
reinforcement learning, ultrasound, despeckling, image enhancement

Abstract:
The electrochemical performance of cobalt-based supercapacitor electrodes is often limited by the relatively smooth surface of pristine nickel foam substrates. To overcome this limitation, a microstructurally engineered nickel foam scaffold was fabricated by introducing a porous nickel microparticle interlayer via screen printing. Cobalt nanostructures were hydrothermally grown on the modified substrate, forming a hierarchical electrode (Co@NF-M), which was systematically compared with electrodes prepared on commercial nickel foam (Co@NF). Structural and spectroscopic analyses supported the formation of predominantly crystalline spinel Co3O4, characterized by mixed Co2 + /Co3+ oxidation states. Morphological analysis further demonstrated a porous cobalt nanostructure anchored onto a roughened nickel scaffold, providing abundant active sites and facilitating electrolyte penetration and ion diffusion. Electrochemical impedance spectroscopy indicated a reduced charge-transfer resistance and improved electron transport compared to the conventional Co@NF electrode. As a result, the Co@NF-M electrode exhibited superior electrochemical performance, delivering specific capacitances of 1278, 1184, 1003, and 602 F g−1 at 0.5, 1, 5, and 10 A g−1, respectively. Furthermore, the symmetric Co@NF-M//Co@NF-M device retained 95% of its initial capacitance after 3000 cycles, demonstrating excellent cycling stability. The enhanced performance is attributed to the engineered nickel scaffold, which promotes more uniform cobalt growth and improves interfacial contact while facilitating electron and ion transport.

Keywords:
Cobalt oxide, Symmetric supercapacitor, Cycling stability, Tailored Nickel foam, Pseudocapacitor behavior

Keywords:
beton osłonowy, projektowanie, trwałość

Abstract:
This study employs molecular dynamics simulations to examine the mechanical properties, fracture toughness, and crack propagation behavior of polycrystalline B6N6, BN, BC3, and C3N4 nanosheets and nanotubes. The effects of the number of grains, temperature, strain rate, edge pre-cracks, and circular-notch defects on Young's modulus, tensile strength, failure strain, and critical fracture toughness is systematically analyzed. Results show that increasing the number of grains reduces both tensile strength and Young's modulus, with BN nanosheets demonstrating the highest overall mechanical performance. Polycrystalline B6N6 exhibits the greatest fracture toughness, followed by BN, BC3, and C3N4, reflecting the role of atomic structure and bonding in energy absorption before failure. Thermal analysis indicates that BN maintains superior mechanical stability at elevated temperatures due to reduced atomic vibrations and stronger B–N bonds. Analyses of pre-cracks and notches reveal that BN is most sensitive to crack propagation, whereas BC3 and C3N4 show crack-insensitive behavior, with failure often initiating at grain boundaries rather than crack tips. Strain rate effects suggest that higher rates enhance fracture toughness by limiting atomic rearrangements and crack growth. For nanotubes, increasing diameter enhances Young's modulus but reduces tensile strength, failure strain, and fracture toughness, with C3N4 nanotubes being most sensitive to temperature. These findings provide detailed insights into the mechanical behavior of polycrystalline nanosheets and nanotubes, guiding the design of nanomaterials with optimized strength, toughness, and thermal stability for advanced applications.

Keywords:
Polycrystalline nanosheetsNanotubesMechanical propertiesFracture toughnessCrack propagation

Keywords:
orthopaedic implants, implant’s destruction, intramedullary nail, bone plate, surface analysis

Keywords:
additive manufacturing, direct energy deposition, thermal history, numerical simulations

Keywords:
high-temperature oxidation, nickel-based superalloys, microstructure, oxide scale formation

Keywords:
complex concentrated alloys, mechanical alloying, powder metallurgy, microstructure, mechanical properties

Keywords:
plastic deformation, Inconel 718, LENS, EBSD

Keywords:
additive manufacturing, LENS, yield surface, deformation, superalloy, inconel, multiaxial, EBSD, pre-deformation, anisotropy

Keywords:
smart materials, piezoelectricity, neural tissue engineering, electrospinning

Keywords:
tissue engineering, 3D printing, gelatin methacryloyl

Abstract:
The delivery of therapeutic agents to the central nervous system (CNS) remains limited by the restrictive nature of the blood–brain barrier (BBB), which prevents most molecules exceeding ~400 Da from reaching neural tissue. This barrier represents a major obstacle in the treatment of disorders such as Alzheimer’s disease and gliomas. MRI-guided focused ultrasound (FUS) combined with intravenous microbubbles offers a noninvasive and spatially targeted strategy to transiently disrupt the BBB (FUS-BBBO), enabling localized drug delivery while maintaining tissue integrity. This project aims to develop and optimize a safe and effective MRI-controlled FUS protocol for BBB opening in a rat model for therapeutic agent delivery. Four different levels of acoustic pressure were applied with the intravenous administration of microbubbles in order to open the BBB. Acoustic emissions from oscillating microbubbles were monitored during sonication to assess treatment response and correlate physical signals with biological outcomes. BBB permeability was evaluated using dynamic contrast-enhanced MRI on a 7 T Bruker BioSpec 70/30 USR scanner with an 86-mm volume Tx/Rx coil, following intravenous gadolinium contrast administration at 0.2 mmol/kg. The immediate post-FUS protocol started within several to ~15 minutes after sonication and included repeated short T1-weighted FLASH scans (TE/TR = 4/18 ms, FA = 12°, 0.3 × 0.3 × 0.3 mm³, TA = 3 min 42 s), followed by a higher-resolution T1-weighted FLASH scan (TE/TR = 6/50 ms, FA = 18°, 0.15 × 0.15 × 0.5 mm³, TA = 10 min 14 s). Pre-FUS MRI included anatomical T2-weighted imaging and T1 mapping, while follow-up scans at 6, 24, 48 and 72 h will be used to monitor BBB closure. Evans blue was used to verify the size of the BBB opening and its correlation with MRI contrast enhancement. Preliminary results indicate reliable MRI visualization of BBB opening shortly after FUS (15-30 min.), with concordant Evans blue extravasation visible post-mortem. Higher acoustic parameters were associated with minor hemorrhagic effects detectable on MRI and histology, underscoring the importance of parameter optimization. This study contributes to refining MRI-guided FUS-BBBO as a controlled and translatable platform for CNS drug delivery.

Keywords:
Supercapacitor, transition metal oxides, asymmetric supercapacitor, hydrothermal

Abstract:
Solid polymer electrolytes with high ionic conductivity, dominant ion transport, and long-term electrochemical stability are essential for next-generation solid-state lithium batteries. In this study, a fully hybrid nanocomposite solid polymer electrolyte based on poly(ethylene oxide) (PEO), POSS-benzyl7(BF3Li)3 nano lithium salt, and POSSPEG13.3 nano plasticizer is developed using solution casting technique, in which both the salt and plasticizer possess organic–inorganic hybrid architectures. The optimized electrolyte containing 40 wt% POSSPEG13.3 exhibits a high room-temperature ionic conductivity of 8.64 × 10−4 S cm⁻¹ and follows Vogel–Tammann–Fulcher (VTF) behavior. Structural and thermal analyses reveal near-complete suppression of PEO crystallinity (∼1%) and good thermal stability up to ∼235 °C. The electrolyte shows excellent mechanical flexibility and a near-unity ion transference number (tion = 0.99). A wide electrochemical stability window of ∼4.7 V vs. Li/Li⁺ is obtained. Solid-state LiFePO4/Li cells deliver an initial discharge capacity of 169.3 mAh g⁻¹ at 0.1 C with 89.8% capacity retention after 100 cycles. These results demonstrate the effectiveness of the fully hybrid electrolyte design for solid-state lithium batteries.

Keywords:
Solid polymer electrolyte, POSS lithium salt, Nano plasticizer, Ion transference number, Solid-state lithium batteries