Abstract: The formation of interfacial charge transfer (ICT) complexes between phenolic ligands and metal oxide surfaces enables surface functionalization strategies with potential applications in catalysis and bioconjugation. In this study, magnetite (Fe₃O₄) nanoparticles were modified with two phenolic ligands, 5-aminosalicylic acid (5ASA) and caffeic acid (CA), to generate ICT complexes capable of covalent or non-covalent enzyme immobilization, respectively. The modified nanomaterials were structurally characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). Horseradish peroxidase (HRP) was immobilized on these functionalized supports. Catalytic activity was evaluated using pyrogallol oxidation assays, with systematic variations in nanoparticle mass and enzyme concentration. The Fe₃O₄/5ASA–HRP system exhibited a maximum activity of 2.5 U per 20 mg of support (approximately 125 U/g), whereas Fe₃O₄/CA showed minimal activity under the same conditions. Data from enzyme loading studies confirmed that 5ASA-enabled covalent attachment resulted in significantly higher immobilization efficiency (up to 1068 mg/g) compared to the CA system. The magnetic properties of Fe₃O₄ allowed for rapid recovery of the biocatalysts using an external magnetic field. These results highlight the effectiveness of ICT-based functionalization for enzyme immobilization, positioning Fe₃O₄/5ASA as a promising platform for robust and reusable biocatalysts in environmental and industrial applications.

Abstract: Uric acid (UA), the end product of purine metabolism in humans, is a crucial biomarker closely associated with various diseases. This study developed a novel enzyme-free colorimetric sensing platform based on starch-derived nitrogen-doped biochar (NC) for the highly sensitive and selective detection of UA in human body fluids. The NC material with a high specific surface area and abundant nitrogen active sites was prepared via a two-step strategy involving hydrothermal synthesis followed by high-temperature pyrolysis, using starch and urea as raw materials. It efficiently catalyzed dissolved oxygen to generate reactive oxygen species (·O2- and 1O2) under mild conditions, which oxidized 3,3',5,5'-tetramethylbenzidine (TMB) to produce a blue-colored product (TMBox). UA reduced TMBox back to colorless TMB, resulting in a decrease in absorbance at 652 nm, enabling the quantitative detection of UA. Key reaction conditions were systematically optimized. Material characterization and mechanistic investigations confirmed the catalytic performance. The method demonstrated a wide linear range of 10-500 μmol·L-1 and a low detection limit of 4.87 μmol·L-1, along with excellent selectivity, stability, and reproducibility. Practical application in human serum and urine samples yielded results consistent with clinical reference ranges, and spike-recovery rates ranged from 95.5% to 103.6%, indicating great potential for real-sample analysis.

Abstract: In this study, a straightforward strategy for the preparation of functional carbon-based materials for hydrazine oxidation (HzOR) is presented. A highly efficient, cost-effective iron (Fe) and manganese-iron (MnFe) supported nitrogen-doped carbon (N-C) material was developed using a hydrothermal synthesis method. Meanwhile, N-C material was obtained from biomass – birch-wood chips – using hydrothermal carbonisation (HTC), followed by the activation and nitrogen doping of the resulting hydrochar. The material has a large specific surface area of 2431 m2 g−1 and a micro-mesoporous structure con-taining over 50% mesopore volume. The morphology, structure, and composition of the MnFe, MnFe/N-C, and Fe/N-C catalysts were determined using scanning electron micros-copy (SEM), X-ray diffraction (XRD), and energy dispersive X-ray spectroscopy (EDX). The activity of the catalysts for the HzOR in an alkaline medium was evaluated using cyclic voltammetry (CV). The deposition of MnFe particles on N-C has been shown to result in a significant enhancement of electrocatalytic activity for HzOR in comparison with pure MnFe particles. The hydrazine oxidation current density values, measured at an electrode potential of 1.6 V vs. RHE, were found to be approximately 7 and 9 times higher on the Fe/N-C and MnFe/N-C catalysts, respectively, than on the MnFe catalyst.

Abstract: Carbon materials are important for the commercial production of supercapacitors and they are very crucial electrode materials. The porous carbon prepared with biomass materials as the precursor is of significance due to the sustainable supply, environmental friendly, and low cost. Biomass-derived carbon (BDC) has been widely investigated and reported as the electrode of supercapacitors. In this work, the recent advancement of BDC for supercapacitors in the last three years is reviewed. The energy storage mechanism, synthesis techniques and biomass classification of BDC are summarized at the beginning of this work. Some new typical cases with different biomass resources as raw materials are addressed. Then, effective strategies to further improve the specific capacitance of BDC including heteroatom doping, designing composites, novel processes, enhancing graphitic degree and unique preparation methods are concluded in detail. Finally, the challenges and future perspectives of porous BDC for supercapacitors are outlined.

Abstract: High-entropy alloys (HEAs) are a class of multi-principal element materials composed of five or more elements in near-equimolar ratios. This unique compositional design generates high configurational entropy, which stabilizes simple solid solution phases and reduces the tendency for intermetallic compound formation. Unlike conventional alloys, HEAs exhibit a combination of properties that are often mutually exclusive, such as high strength and ductility, excellent thermal stability, superior corrosion and oxidation resistance. The exceptional mechanical performance of HEAs is attributed to mechanisms including lattice distortion strengthening, sluggish diffusion, and multiple active deformation pathways such as dislocation slip, twinning, and phase transformation. Advanced characterization techniques such as transmission electron microscopy (TEM), atom probe tomography (APT), and in-situ mechanical testing have revealed the complex interplay between microstructure and properties. Computational approaches, including CALPHAD modeling, density functional theory (DFT), and machine learning, have significantly accelerated HEA design, allowing prediction of phase stability, mechanical behavior, and environmental resistance. Representative examples include the FCC-structured CoCrFeMnNi alloy, known for its exceptional cryogenic toughness, Al-containing dual-phase HEAs, such as AlCoCrFeNi, which exhibit high hardness and moderate ductility and refractory HEAs, such as NbMoTaW, which maintain ultra-high strength at temperatures above 1200°C. Despite these advances, challenges remain in controlling microstructural homogeneity, understanding long-term environmental stability, and developing cost-effective manufacturing routes. This review provides a comprehensive and analytical study of recent progress in HEA research (focusing on literature from 2022–2025), covering thermodynamic fundamentals, design strategies, processing techniques, mechanical and chemical properties, and emerging applications, through highlighting opportunities and directions for future research. In summary, the review’s unique contribution lies in offering an up-to-date, mechanistically grounded, and computationally informed study on the HEAs research-linking composition, processing, structure, and properties to guide the next phase of alloy design and application.

Abstract: Biodegradable polymeric composites reinforced with natural fillers represent one of the most promising routes toward low-impact, circular, and resource-efficient materials. In recent years, a growing number of studies has focused on the valorization of plant- and animal-derived organic waste, ranging from agricultural residues and natural fibers to marine and livestock by-products. This review provides a comprehensive and compar-ative overview of these systems, analyzing the nature and origin of the waste-derived fillers, their pretreatments, processing strategies, and the resulting effects on mechanical, thermal, functional, and biodegradation properties. Particular attention is dedicated to the role of filler composition, morphology, and surface chemistry in governing interfacial adhesion and end-use performance across different polymeric matrices, including PLA, PCL, PBS, PHA, PHB, PBAT, and commercial blends such as Mater-Bi®. The emerging applications of these biocomposites, such as packaging, additive manufacturing, agri-culture, biomedical uses, and environmental remediation, are critically discussed. Overall, this work provides fundamental insights to support the development of the next generation of biodegradable materials enabling the sustainable valorization of organic waste within a circular-economy perspective.

Abstract: This study aims to develop a formulation for bio-resins derived from Sengon bark for application in plywood products. The research results demonstrated that bio-resin formulas for plywood applications include Bark Extract (E): Tapioca (T): Resorcinol (R): Formaldehyde (F) = (1.00 : 0.025 : 0.50 : 0.1) % and E : T : R : F : Resin (PF) = (1.00 : 0.025 : 0.025 : 0.1 : 0.025) %. Laboratory trials show that both adhesive formulations technically have potential for plywood production applications. Bio-resin adhesives exhibit high moisture resistance. Sengon bark extract, tapioca starch, resorcinol, and formaldehyde can be formulated into bio-resins with alkaline catalysts or PF fortifiers, maintaining a final pH of 10–11. The resulting adhesives show potential for plywood production, exhibiting high moisture resistance.

Abstract: In this work, the sintering behavior of tapes prepared via tape casting from stainless-steel and zirconia powders is investigated by optical – as well as push-rod – dilatometry. Both methods are compared in terms of sample preparation, measurement conditions and advantages and disadvantages. The experimental work shows the advantages of optical dilatometry in characterizing of the sintering behavior of load free sintering tapes and the possibilities of simultaneous observation of sample warpage and deformation. Push-rod dilatometry requires a constant load on the sample, which influences the sintering process in the case of tapes with lower mechanical stability but has advantages because of the higher accuracy in measuring dimensional changes. In the case of warpage, the shrinkage due to sintering of the sample is superimposed by an irregular deformation process that can be separated by analytical methods. No in-plane shrinkage anisotropy of the tapes is observed for either type of tape. In the case of the push-rod dilatometer, an additional peak in the shrinkage rate is observed in the early stage of compaction and a slight shift and increased maximum of the compaction rate. This is most likely due to the effects of the contact pressure of the push-rod.

Abstract: Graphitic carbon nitride (g-C₃N₄) is a promising metal-free photocatalyst, yet its efficiency remains limited by rapid charge recombination. Heteroatom doping offers an effective means to tailor its electronic structure and enhance photocatalytic performance. In this study, structural and electronic modifications in triazine-based g-C₃N₄ (g-CN1) induced by phosphorus incorporation were systematically investigated through a combination of experimental characterization and density functional theory (DFT) calculations, providing complementary insights into the atomic-scale bonding and electronic properties of pristine and phosphorus-doped g-C₃N₄ (P@g-CN1). Both pristine g-CN1 and P@g-CN1 were synthesized via thermal polycondensation of melamine using H₃PO₄ as the dopant source. Transmission electron microscopy, X-ray diffraction, and photoluminescence spectroscopy reveal that phosphorus doping preserves the fundamental lattice topology while inducing lattice relaxation, surface corrugation, and flake extension—features that are well rationalized by the Topology Conservation Theorem. Phosphorus incorporation markedly suppresses charge recombination and enhances charge separation efficiency in the P@g-CN1 composite. DFT analysis confirms that phosphorus atoms induce downward shifts of the valence and conduction bands and introduce localized midgap states near the Fermi level, thereby enhancing electronic delocalization and facilitating carrier transport. The P@g-CN1 system retains its semiconducting character with pronounced σ–π hybridization between carbon and nitrogen 2p orbitals. The strong agreement between experimental results and theoretical analysis underscores the high degree of complementarity between these approaches. This provides a coherent understanding of the structure–property relationships in phosphorus-doped g-C3N4, thereby guiding the rational design of next-generation, metal-free two-dimensional photocatalysts and photovoltaic materials.

Abstract: SERS is an emerging technique for the rapid sensing of key bioactive molecules, such as glucose, which has relatively low signal levels using normal Raman spectroscopy. SERS of glucose at extremely low concentration levels or high enhancement factors (EFs) is demonstrated here using relatively inexpensive, commercial multilayer graphene nanoplatelet (GNP) substrates produced from natural graphite. Three approaches for modifying the GNPs for SERS were used: the first method involved drop-coating of gold nanoparticles from solution on the GNPs, the second method used a combination of drop-coating the gold nanoparticles followed by the deposition of tri-ethylene glycol (TEG) layers to partition the glucose on the surfaces of the gold nanoparticles to further increase the SERS signal, and the third method used irradiation of the GNPs in a nitrogen-argon radio frequency (RF) plasma to create nitrogenous defect sites on the graphene layers to increase the SERS signal. Glucose in aqueous solutions was detected at concentrations down to 10-8 M, 10-10 M and 10-11 M, respectively, with corresponding high enhancement factors (EFs) for the three types of modified GNP substrates.

Abstract:

This study examines the influence of sintering temperature on the structural and transport properties of GdBa₂Cu₃O₇ (Gd123) superconductors prepared from nano-sized precursors via the co-precipitation method. The metal-oxalate precursor (average particle size <50 nm) was calcined at 900 °C for 12 hours, then the prepared pellets were sintered in oxygen at 920–950 °C for 15 hours. All samples showed metallic properties and a sharp superconducting transition. Critical temperatures T_C(R=0) were 94–95 K, with higher sintering temperatures steadily boosting critical current density. X-ray diffraction confirmed orthorhombic Gd123 as the dominant phase, with its phase fraction increasing from 92% to 99.8% as the sintering temperature increased. SEM micrographs showed large, densely packed grains, with higher sintering temperatures promoting improved grain connectivity and reduced porosity. The sample sintered at 950 °C exhibited the most favorable transport performance, attributed to enhanced intergranular coupling and the presence of nanoscale secondary phases acting as effective flux-pinning centers. Overall, these results demonstrate that careful control of sintering temperature can significantly optimize the microstructure and superconducting properties of Gd123 materials, supporting their advancement for practical electrical and magnetic applications.

Abstract: The paper presented here examines the decomposition of hydrazine on the surface of single-crystalline germanium at 650oC, the kinetics of the nitride formation process at 650°C was studied using a microgravimetric method and the question of the possibility of using α-Ge3N4 and mixtures of α- and β-Ge3N4 as a photocatalyst was considered.

Abstract: Polydiacetylene (PDA) nanovesicles are widely recognized as versatile chromatic sensing platforms, exhibiting a visible blue-to-red colorimetric transition in response to stimuli such as temperature, pH, and molecular recognition events. Alpha-cyclodextrin (α-CD) is known to interact with PDA vesicles, inducing this transition through host–guest inclusion at the vesicle interface. Here, we demonstrate that incorporating the EO–PO–EO triblock copolymer L64 into PDA suspensions enables precise modulation of this α-CD-induced chromatic response. Increasing L64 concentration progressively suppresses the blue-to-red transition, as the copolymer competes with PDA headgroups for α-CD inclusion. Isothermal titration calorimetry revealed that α-CD exhibits a stronger affinity for L64 (K = 11,300) than for PDA vesicles (K = 4,000), with both processes being spontaneous (ΔG° ≈ –21 kJ mol⁻¹) and entropy-driven. Importantly, the self-assembled PDA vesicular structure remains intact, as confirmed by phase separation and optical analyses, highlighting that the colorimetric inhibition arises from supramolecular competition rather than structural disruption. This work introduces a new supramolecular strategy to negatively regulate PDA affinity-chromism through competitive inclusion complexation with biocompatible triblock copolymers, offering a robust and tunable route for developing responsive and safe chromatic sensors.

Abstract: Laser slicing has emerged as a promising low-kerf and low-damage technique for fabricating SiC wafers; however, its influence on crystal integrity, near-surface modification, and charge-transport properties requires further clarification. In this study, a heavily N-doped 4° off-axis 4H-SiC wafer was sliced using a UV picosecond laser, and both the laser-irradiated surface and the laser-sliced (detached) surface were comprehensively characterized. X-ray diffraction and pole-figure measurements confirm that the 4H stacking sequence and macroscopic crystal orientation are preserved after slicing. Raman spectroscopy, including analysis of the folded transverse optical (FTO) mode and LO phonon–plasmon coupled (LOPC) modes, enabled dielectric-function fitting and determination of the plasmon frequency, yielding a free-carrier concentration of approximately 3.1 × 10¹⁸ cm⁻³. Hall measurements provide consistent carrier density, mobility, and resistivity, demonstrating that the laser slicing process does not degrade bulk electrical quality. Multi-scale AFM, angle-resolved XPS, SIMS, and TEM/SAED reveal the formation of a thin amorphous/polycrystalline modified layer and an oxygen-rich region confined to the near surface, with significantly increased roughness and thicker modified layers on the hill regions of the sliced surface. These results show that UV laser slicing maintains the intrinsic crystal and electrical properties of 4H-SiC while introducing localized nanoscale surface damage, which must be minimized through optimized slicing parameters and subsequent surface-finishing processes.

Abstract: Various methods for classifying and evaluating the shape, size, and surface texture of sand particles are examined, highlighting their importance in concrete mixture properties. The study emphasizes the role of particle morphology in determining concrete workability and segregation, particularly in glass fiber reinforced (GRC) thin-layer concrete for building facade panels. The effects of different aggregate types on concrete workability and segregation are analyzed, showing that aggregates with spherical particles and a lower elongation index improve mixture consistency and reduce segregation. Three types of fine aggregates were used for the research. Thin-layer concrete dispersively reinforced with concrete fiberglass using aggregates of different shapes is characterized by a layering of the mixture. The workability and segregation of the fine-grained fiberglass-reinforced concrete mixture depend on the shape of the aggregate particles. Up to 50% of the quartz sand can be replaced with granit stiftings or natural sand, as measured by the segregation index. Increasing the amount of natural sand from 10% to 50% also increases the segregation index from 1.9 to 2.6, and when using granite stiftings aggregates from 2.6 to 3.5, respectively. The segregation index can be calculated according to the method proposed in this paper. Aggregates with spherical particles are more suitable for this thin-layer GRC concrete.

Abstract: Spent coffee grounds (SCG) are an abundant, carbon-rich residue suitable for converting into biochar through a thermochemical process. In this study, biochar was produced from SCG using a two-step pyrolysis-CO2 activation process and a one-step CO2 assisted pyrolysis method to compare their physicochemical and structural properties. Results showed that CO2 activation significantly increases the porosity and surface area, from 9.8 m²/g for non-activated biochar (BCK) to 550.6 m²/g for BCK-CO2 and 671.0 m²/g for SCG-CO2. FTIR and Boehm titration analyses confirmed a decrease in surface oxygenated groups after CO2 treatment, and SEM-EDX and XRD analyses indicated a structural reorganization. The one-step CO2 assisted pyrolysis produces biochar with a more uniform pore structure, a higher degree of carbonization, and better textural properties than the two-step method. Therefore, using CO2 directly during pyrolysis can be an efficient and sustainable method to obtain highly porous biochar from spent coffee grounds, reduce energy demands, and make valuable organic waste.

Abstract: The complex study of the influence of the H2SeO4 electrolyte temperature on the porous anodic aluminum oxide (AAO) composition and defects, morphological, luminescent properties is performed. The synthesis temperature increasing leads to decrease of AAO cell diameter from 85-115 nm to 38-58 nm (depending on the electrolyte concentration) and increases AAO walls etching that can even lead to AAO etching to individual fibers at 40°C. Selenium concentration in the samples formed in 0.5-1.5 M H₂SeO₄ at 5-40°C does not exceed 2 at.% and becomes undetectable at 40°C. It is established that the formation of the nanocrystalline phase Al₂O₃ in H₂SeO₄ electrolyte is observed at 40°C. The samples exhibit very weak photoluminescence. It was shown that in AAO formed in H2SeO4 there are 3 types of paramagnetic centers: F⁺ centers (NₛF=8.2·1015 g^-1), newly discovered centers in which the unpaired electron belongs to an oxygen atom (NₛO=1017 g^-1), and paramagnetic centers associated with selenate radicals (NₛS=6·1018 g^-1). By comparison of the photoluminescence spectra and defect concentrations, it is assumed that the luminescent properties of AAO obtained in selenic acid are exclusively determined by F⁺ centers. The centers associated with other reaction products do not contribute to the AAO luminescent properties.

Abstract: Owing to its corrosion resistance, stainless steel is a sustainable alternative to carbon steel as a structural material in challenging seawater environments. Studies on carbon steel indicate that among all marine corrosion zones (i.e., atmospheric zone, splash zone, tidal zone, and immersed zone), the rate of corrosion is particularly high in the splash zone, above the seawater level, due to the recurrent splashing of seawater with high levels of oxygen and chloride content. Nevertheless, the information on the extent of localized corrosion (i.e., pitting and crevice corrosion) on stainless steel in the splash and tidal zones is scarce and, in most cases, limited to standard austenitic grades. In this work, we present the pitting and crevice corrosion results on lean duplex, duplex, and super duplex stainless steels after two years of field exposure in the North Sea (site at Heligoland South Harbour). Parallel exposure of coupons in splash, tidal, and immersed zones allows comparison of the extent of corrosion in each zone and enables proper material selection for structural applications in marine environments.

Abstract: The vibrational properties of the chiral sulfoxide methyl-p-tolyl-sulfoxide (Metoso) were investigated by infrared and Raman spectroscopy in the solid, liquid and aqueous solution phases, for both the enantiopure compounds and their racemic mixture. Experimental data were complemented by DFT calculations on the isolated enantiomer and on the two RR and RS dimeric conformers to support spectral interpretation and mode assignment. The IR and Raman spectra of the crystalline enantiomer and racemic mixture are similar, indicating comparable molecular organization and intermolecular interactions in the solid state. Upon melting, band broadening and frequency shifts are observed, consistent with molecular disorder and the breaking of weak intramolecular interactions, accompanied by changes in the S–O and S–CH₃ and C-H stretching frequencies. In aqueous solution, further broadening and opposite shifts of these bands reflect the formation of Metoso–H₂O complexes through hydrogen bonds. Theoretical spectra reproduce the observed trends and confirm that either solvent or phase transitions control the balance between intra- and intermolecular interactions thus influencing the vibrational degrees of freedom of the model chiral sulfoxide.

Abstract: Textiles can host microorganisms making antimicrobial function an essential safety feature. An ideal antimicrobial agent is non-nontoxic, stable, and durable. This study explores a core-shell nanofiber with core of cationic biopolymer ε-poly-L-lysine (PL) and shell of structurally similar and biocompatible polyamide-6 (PA). The core-shell structure is expected to have stable antimicrobial function than its monolithic counterpart. Further, thermal crosslinking is expected to prevent rapid diffusion of the water-soluble PL. Therefore, this study establishes a comparison between a monolithic (Control), a core-shell (CS), and thermally crosslinked core-shell (CL-CS) nanofiber of PL and PA. Morphological analysis confirmed the successful generation of the core-shell nanofibers. The samples exhibited hydrophilic behavior that is desirable in various functional textiles. All the samples exhibited antimicrobial function. Unlike control, CS and CL-CS showed no significant difference between the antimicrobial activity after 24 hours and 21 days of bacterial incubation. Therefore, the core-shell structure allowed sustainable and durable antimicrobial action. Lastly, CL-CS sample exhibited reusable antimicrobial function owing to the core-shell structure paired with thermal crosslinking. This study showcases a fiber system with non-toxic, durable, and reusable antimicrobial function. This study builds grounds for the development and multifaceted holistic characterization of safe, stable, and scalable antimicrobial textiles.