Chemistry and Materials Science

Abstract: Additive manufacturing using vat photopolymerization (VPP) resin materials has gained attention for fabricating dental prostheses; however, the effects of material type and build angle on their properties remain unclear. We compared the mechanical properties of two filler-containing VPP hybrid resins, SprintRay Ceramic Crown (CC) and OnX Tough 2 (OT), with those of a conventional polymethyl methacrylate (PMMA) disc material, and evaluated the influence of build angle on surface characteristics, dimensional accuracy, and mechanical performance. Specimens were fabricated using a DLP system at build angles of 0°, 45°, and 90°. Vickers hardness, surface morphology and roughness, dimensional deviations, flexural strength, elastic modulus, and fracture energy were assessed according to relevant standards. CC exhibited significantly higher hardness and elastic modulus than PMMA and OT, whereas OT showed the highest fracture energy. Surface morphology and roughness were strongly affected by build angle, with 45° producing distinct periodic patterns and increased roughness. Dimensional evaluation revealed a tendency toward overbuilding, particularly in the vertical direction at 45°. Flexural properties were also influenced by build angle, with 45° generally providing favorable performance. Both material composition and build angle affect VPP-fabricated dental resin performance, highlighting the importance of appropriate material and processing selection for clinical applications.

Abstract: This work reports the synthesis, characterization, and photocatalytic performance of mul-tifunctional spheres based on AgNPs-doped TiO2-Fe3O4 embedded in an alginate-chitosan biopolymeric matrix for the removal of organic contaminants from water. The composite powders exhibited a nanocrystalline structure composed of anatase TiO2 (~20 nm) and magnetite (~25 nm), with homogeneously dispersed Ag nanoparticles, as observed by SEM. The spheres presented a mainly submicrometric particle size distribution (0.55-0.92 µm), favoring high surface area and colloidal stability. Under simulated solar irradiation, the material achieved efficient photocatalytic degradation of methylene blue, with a pseu-do-first-order rate constant of 0.112 h⁻¹ and ~46 % decolorization after 5 h. UV-Vis spectra showed progressive attenuation of the dye absorption band without accumulation of in-termediates. The spheres also exhibited strong antibacterial activity, reaching 87 % reduc-tion of total coliforms and >93 % of fecal coliforms after 5 h of irradiation. Magnetic recov-ery tests confirmed rapid separation and reuse without performance loss. The enhanced activity is attributed to the synergistic interaction among plasmonic Ag, photocatalytic TiO2, redox-active Fe3O4, and the adsorptive carbon-biopolymer matrix. The material ex-hibited strong antibacterial activity, achieving over 90% removal of fecal coliforms after 5 h of irradiation Therefore, the developed AgNPs-doped TiO2-Fe3O4 spheres represent a sus-tainable, reusable and efficient material for solar-assisted water sanitation.

Abstract: This study investigates the energy-efficient mechanochemical activation of fly ash derived from Kazakh coals for the development of sustainable cementitious composites. The ap-proach aims to enhance the reactivity of aluminosilicate materials while reducing the en-ergy demand and carbon footprint associated with conventional clinker-based cement production. Mechanochemical activation was performed to increase the specific surface area and in-duce structural defects in the glassy phase of fly ash, thereby improving its reactivity. Chemical activation using sodium hydroxide (NaOH) was applied to promote intensive pozzolanic reactions and accelerate dissolution kinetics. The optimal activation conditions were identified as 15 min of mechanical treatment com-bined with 4% NaOH. Under these conditions, the compressive strength reached 35.5 MPa at 28 days, exceeding that of the reference cement (35.0 MPa). At fly ash contents of 15–20%, the composites maintained or improved strength, whereas an increase to 30% resulted in a reduction to 31.5 MPa. Mechanical activation increased the specific surface area to approximately 4800–5000 cm²/g; however, prolonged grinding (up to 30 min) led to particle agglomeration and a de-crease in strength to about 28 MPa. Chemical activation enhanced reaction kinetics without significantly affecting particle fineness. Microstructural analysis revealed the formation of a dense and homogeneous matrix dom-inated by C–S–H, C–A–S–H, and N–A–S–H gel phases with reduced porosity. The com-bined activation approach demonstrated a clear synergistic effect, enabling up to 20% ce-ment replacement without loss of performance. Importantly, the proposed method provides a low-energy pathway for the utilization of industrial waste, contributing to reduced clinker consumption and lower CO₂ emissions. The results highlight the significant potential of Kazakhstan’s industrial by-products for the production of energy-efficient, environmentally friendly, and cost-effective construction materials.

Abstract: Composite components with variable thickness structures often suffer from insufficient forming pressure during curing due to complex pressure transfer in regions with abrupt thickness changes, which easily causes void defects and degrades component performance. In this study, a mechanical vibration-assisted double vacuum bag process is proposed. Finite element analysis of the vibration energy field in saturated porous composites is conducted, and curing experiments for variable-thickness specimens are designed. The effects of vibration, vacuum, and their synergy on void characteristics and mechanical properties are studied using microscopic characterization and mechanical tests. The results indicate that vibration can effectively facilitate gas discharge and accelerate resin flow, while the double vacuum bag process reduces gas discharge resistance in the early curing stage by delaying the vacuum negative pressure application, yet it also results in insufficient resin flow due to this delay. Through the synergistic optimization of vibration-assisted energy field parameters and the double vacuum bag process, gas-induced and flow-induced voids can be effectively suppressed while ensuring curing efficiency, reducing the macroscopic porosity of variable-thickness regions from 8.34% (single vacuum bag process) to 0.43%. This study provides a new approach for the high-quality curing and manufacturing of variable-thickness composite components.

Abstract: Metal-supported solid oxide fuel cells (MS-SOFCs) represent a promising advancement for intermediate-temperature energy conversion applications due to their enhanced mechanical robustness and rapid startup capabilities. This investigation systematically evaluates the correlation between yttria-stabilized zirconia (8YSZ) electrolyte thickness and electrochemical performance in Ni-Fe supported architectures. Three distinct cells featuring YSZ electrolyte thicknesses of 7.05, 14.2, and 21.2 μm were fabricated via tape casting and co-sintering at 1350°C, maintaining identical Ni-Fe support (280 μm) and Ni-YSZ anode (22 μm) thicknesses. Electrochemical characterizations revealed a clear inverse relationship between electrolyte thickness and cell performance. The cell with the thinnest electrolyte (7.05 μm) achieved the highest power density of 0.32 W/cm² at 800°C, representing a 4.6-fold improvement compared to the thickest variant (21.2 μm). Electrochemical Impedance Spectroscopy and Distribution of Relaxation Times analysis confirmed that ohmic resistance dominated the total cell impedance, scaling linearly with electrolyte thickness while electrode kinetics remained consistent. This study establishes that thin YSZ electrolytes (≤8 μm) maximize MS-SOFC performance while maintaining structural integrity through co-sintering fabrication, providing an essential design for high-performance metal-supported fuel cell development.

Abstract: The solidification process is crucial for preparing high-performance ceramic super-conductor. The solidification process is strongly dependent on the characteristics of the starting powder, including particle size, morphology, and phase purity. This review concisely examines the study on four key ceramic superconductors: REBCO, Bi-2212, FeSeTe, and MgB₂. In REBCO, additives such as CeO₂, Pt, or BaO₂ powder can refine the RE-211 phase. In Bi-2212, Pb or Nb powder additions stabilize the high-T_c phase. For FeSeTe, doping with F or Co modifies phase separation and introduces Δκ pinning. Meanwhile, in MgB₂, the incorporation of SiC nanoparticles powder generates effective pinning centers. Concurrently, processing conditions exert a decisive influence on the final microstructure, as demonstrated by the TSMG/TSIG route in REBCO, partial melting parameters for Bi-2212, specific cooling protocols and thermal treatments for FeSeTe, and optimized sintering and post-annealing processes for MgB₂. Future research directions should prioritize fundamental understanding of phase separation mechanisms during powder processing, development of multi-component doping strategies for powder modification, and advancement of scalable powder processing routes for practical conductor architectures.

Abstract: This study investigates the effect of progressive CaO/SrO substitution on the structure, crystallisation behaviour, and coordination chemistry of fluorapatite-forming glass-ceramics in the SiO₂–Al₂O₃–P₂O₅–CaO/SrO–CaF₂ system. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), ATR-FTIR spectroscopy, ³¹P and ¹⁹F MAS-NMR, and transmission electron microscopy (TEM) were employed to probe both crystallisation and local structural environments. Increasing SrO content reduced the glass transition temperature and suppressed homogenous nucleation, promoting surface-nucleated fluorapatite (Ca5−x​Srx​(PO4​)3​F) formation. XRD confirmed fluorapatite as the primary crystalline phase and revealed systematic lattice expansion consistent with partial Sr²⁺ incorporation. ¹⁹F MAS-NMR indicated limited Sr substitution at Ca(II) sites (solid-solution), while ³¹P MAS-NMR demonstrated pronounced phosphorus deshielding, reflecting sensitivity of phosphate tetrahedra to local coordination distortion rather than extensive Sr occupancy. Integrating these findings provides a comprehensive framework for interpreting structural and coordination changes in Sr-fluorapatite glass-ceramics.

Abstract: The aim of this study was to investigate the adhesion of primary colonizers of the oral biofilm on five adhesive restorative materials. For each material (Admira Fusion, Clearfil AP-X, Durafill VS, Filtek Supreme XTE, Venus Diamond) sixteen test specimens were prepared according to a standardized protocol. For pellicle formation, the specimens were incubated for two hours at 37 °C with sterile-filtered inactivated human saliva. The bacteria (S. oralis, S. gordonii, S. sanguinis, S. mitis, A. spp.) were cultivated and suspended. A bacteria mix was prepared from the suspensions. The specimens with pellicles were wetted with the bacterial mix and incubated at 37 °C for 8 hours. The total genomic DNA of the adhered bacteria was isolated and subsequently quantified using SYBR Green qPCR. For S. gordonii, S. oralis and A. spp., no significant differences in the amount of adhered bacterial DNA were found between the different materials. DNA concentration of S. mitis was significantly higher on Filtek Supreme XTE compared to the other materials. Significantly higher DNA concentrations of S.sanguinis could also be detected on Filtek Supreme XTE compared to Clearfil AP-AX and Durafill VS.

Abstract: This study aimed to develop a recycling process for reintegrating dental zirconia waste into CAD/CAM systems and to demonstrate the feasibility of producing functional products from the recycled material. The process began with the purification of zirco-nia, followed by the fabrication of pre sintered blocks compatible with these systems. Subsequently, sintered commercial and recycled zirconia were characterized and compared through density measurements, Vickers hardness, flexural strength, X ray diffraction, hydrothermal degradation analysis, and scanning electron microscopy. The results showed that recycled zirconia exhibits structural properties suitable for practi-cal applications, enabling the fabrication of several industrial prototypes. Overall, this work demonstrates that high value materials such as zirconia can be successfully recy-cled and reintegrated into manufacturing workflows, thereby reducing harmful waste while contributing to environmental sustainability and cost reduction.

Abstract: The increasing occurrence of persistent and bio-recalcitrant organic pollutants in aquatic environments necessitates the development of more resilient and efficient water treatment technologies. Conventional treatment processes often fail to remove such stable contaminants, prompting growing interest in integrated advanced systems. Photocatalytic membranes represent a promising solution due to the synergistic combination of separation and catalytic degradation. In this study, ZnO thin films were deposited by spin coating onto smectite–zeolite ceramic membranes (MS10/Z90), with one to three layers applied to control catalyst thickness (M1–M3). SEM analysis showed that increasing the number of layers led to a thicker, more homogeneous ZnO coating, while XRD confirmed enhanced crystallinity and larger crystallite size. Water permeability decreased from 623 L.h-1.m-2.bar-1 for the uncoated MS10/Z90 membrane to 506, 439, and 350 L.h-1.m-2.bar-1 respectively for M1, M2, and M3 after coating. Photocatalytic performance was assessed using Rhodamine B (RhB) as a model dye, achieving degradation efficiencies of 83.0%, 94.6%, and 99.1% for M1, M2, and M3, respectively, following pseudo-first-order kinetics. The free radical scavenging assays confirmed that hydroxyl radicals (•OH) were responsible for the RhB conversion.These results highlight the key influence of ZnO layer thickness and mass transfer on photocatalytic performance, de-monstrating the multifunctionality of ZnO-coated membranes, including efficient pollu-tant degradation and self-cleaning capability.

Abstract: Eleven resin cements, used as core build-up materials in this study, were evaluated via the following measurements: (a) push-out force between root dentin and fiber post; (b) pull-out force between core build-up material and fiber post; (c) shear bond strength of resin cement to root dentin; (d) flexural strength of resin cement; and (e) flexural modulus of elasticity of resin cement. All tests were performed at two time periods: after 1-day storage in water (Base) and after 20,000 thermocycles (TC 20k). For the push-out test, single-rooted human premolars were used to create simulated cavities. The specimens were sectioned horizontally perpendicular to their long axes into 2-mm slices. These slices were then subjected to push-out test to determine the bond strength between human root dentin, resin cement layer, and the fiber post. There were no significant differences in bond strength between Base and TC 20k. Therefore, surface pretreatments of multiple substrates with universal adhesives for fiber post cementation could ensure not only strong, but also durable, adhesion over time.

Abstract: The incorporation of recycled metallurgical slags into refractory materials constitutes a promising approach to enhancing sustainability in the refractory industry. This study investigates the effect of vanadium-bearing slag aggregates as partial replace-ments for tabular alumina in castables and compares their behaviour with high-alumina and bauxite-based castables. Two vanadium-bearing slags with differ-ent mineralogical compositions were introduced in the 1-3 mm aggregate fraction with substitution up to 25 wt.%. Their effects on microstructure, thermo-mechanical performance and corrosion resistance were evaluated. The introduction of vanadi-um-bearing slag significantly alters the microstructure of the castables, affecting their performance. Both slags displayed grains with higher porosity, microcracking, and heterogeneity compared with tabular alumina, but show similarities with bauxite grains. Slag 1, enriched in calcium aluminate phases, provides limited mechanical strength but improved corrosion resistance due to improved bonding with the matrix. Slag 2, containing a higher spinel content, enhances mechanical strength, showing behaviour comparable to bauxite-based castables, particularly at 10 wt.% replacement. Vanadium is mainly present in metallic form and as Mg(Al,V)2O4 spinel in both slags. Upon firing, vanadium migrates toward grain boundaries and reacts with surround-ing calcium aluminate phases to be incorporated in Ca(Al,V)2O4 and Ca(Al,V)4O7, while the spinel phase remains stable.

Abstract: Porous Ca₂Mg₂Al₂₈O46 (C₂M₂A₁₄) ceramics are highly competitive candidates in the field of critical metal filtration due to their attractive non-metallic inclusions removal capacity. However, the low mechanical strength and inadequate thermal shock resistance (TSR) of these materials restrict their further application. In this work, ZrO₂ toughened C₂M₂A₁₄-based porous ceramics are fabricated by using the polymer sponge replica method. Nano-sized ZrO₂ particles derived from nano-ZrO₂ sol are beneficial to enhance the mechanical properties and TSR of porous ceramics. The optimized porous C₂M₂A₁₄ ceramics exhibit robust compressive strength (2.15 MPa), good residual strength ratio (66.4%) and excellent filtration efficiency in the reduction of total oxygen content (68.4%) by adding 3 wt% ZrO₂ sol. These excellent comprehensive properties of as-prepared porous C₂M₂A₁₄ ceramics make it a potential alternative material for critical metal filtration.

Abstract: Concentrated solutions of polycarbosilane (PCS) are critically important for the development of continuous SiC precursor fibers, where solvent–polymer interactions govern rheology, viscoelastic stability, and spinnability. In this work, PCS solutions in two nonpolar hydrocarbon solvents with different molecular architectures as linear n-heptadecane and bicyclic decalin were systematically investigated over a wide concentration range, with emphasis on the semi-dilute entangled and concentrated regimes relevant to solution-based fiber spinning. A combined experimental approach involving steady and oscillatory rheometry and Fourier-transform infrared (FTIR) spectroscopy was used to elucidate the influence of solvent structure on solvation, viscoelastic response, microstructural organization, and local intermolecular interactions. Despite similar dilute-solution interaction parameters, the concentrated regimes exhibit pronounced solvent-dependent differences in elasticity, flow behavior. For the first time, linear heptadecane is identified as a viable and technologically promising solvent for PCS, enabling the formation of termostability homogeneous concentrated solutions with enhanced deformability. This behavior opens a realistic pathway toward a new solution-based fiber-spinning route based on elasticity-controlled processing. The results demonstrate that solvent molecular geometry governs the structure–rheology–processability relationship of concentrated PCS systems rather than solubility parameters alone, providing a new framework for solvent selection in SiC precursor fiber technologies.

Abstract: The utilization of slag-based materials as non-carbonated CaO sources has attracted increasing attention as a strategy to reduce limestone consumption and CO₂ emissions in cement manufacturing. However, compressive strength development in cementitious systems incorporating slag and CaCO₃ replacement is governed by complex interactions among slag chemistry, mixture design, and physical properties, which makes systematic interpretation and prediction challenging. In this study, a structured dataset was compiled from previously published experimental investigations on clinker and cement systems incorporating various slag types and CaCO₃ replacement levels. The dataset integrates slag chemical composition, mixture design parameters, and physical properties with compressive strength measured at 3 and 28 days. Based on observed experimental trends, compressive strength prediction at multiple curing ages was formulated as a multi-output regression problem to explicitly account for the correlated nature of strength development over time. The results reveal clear nonlinear relationships between compressive strength, curing age, and multiple material parameters. Mixed-slag systems generally exhibit higher early-age strength compared to single-slag systems at comparable CaCO₃ replacement levels, while differences among systems become less pronounced at later ages. These findings indicate that compressive strength at different curing ages is interrelated and influenced by shared material characteristics rather than independent variables. Overall, this study provides a data-driven analysis of strength development trends in slag-blended cementitious materials and establishes a consistent literature-based dataset framework suitable for multi-age strength modeling. The proposed approach offers a transparent basis for future predictive modeling and optimization of cement systems incorporating slag-based non-carbonated CaO sources.

Abstract: 0.006Pb(Mn1/3Ta2/3)O3-0.114Pb(Ni1/3Ta2/3)O3-0.43PbZrO3-0.45PbTiO3 lead-based ceramics (PMT-PNT-PZT) were synthesized via the solid-state reaction at different sintering temperatures to study their effects on phase structure, microstructure, and electrical properties. The maximum mechanical quality factor (Qm) and relative permittivity (εr) were achieved at the sintering temperature of 1200 °C. The piezoelectric constant d33 of 400 pC/N was obtained at 1180 °C, which is attributed to the high grain density and the significant contribution from the remanent polarization and permittivity product (Prεr = 39115 μC/cm2). Compared with commercial PZT4 ceramics, the present composition sintered at 1180 °C exhibits an optimal balance between d33 and Qm, together with the superior figure of merit (FOM = 2.04 × 10⁵ pC/N). Furthermore, it demonstrates excellent temperature stability in electromechanical coupling performance.

Abstract: Resin-matrix ceramics are increasingly used in digital dentistry due to their tooth-like elasticity and ease of handling. Color stability is critical for long-term clinical success. This study evaluated the effects of surface finishing and immersion in beverages on the color stability of four resin-matrix ceramics (Cerasmart, Lava Ultimate, Shofu Block HC, and Vita Enamic). A total of 256 specimens were prepared and divided into mechanical polishing and glazing. Glazing was performed using a light-polymerized resin-based surface coating agent (Optiglaze). Specimens were immersed for 14 days in coffee, red wine, cola, or water. Color differences were measured using the CIEDE2000 formula. Three-way repeated measures ANOVA was used to evaluate the color differences, and post hoc analyses were performed using Tukey and Bonferroni tests, with a significance level of p < 0.05. Results showed that surface finishing, material type, beverage type, and immersion time significantly affected color stability. Coffee and red wine caused clinically unacceptable color differences, while mechanically polished specimens demonstrated higher color stability than glazed ones. Lava Ultimate showed the lowest, and Cerasmart the highest, color stability. These findings highlight the role of surface finishing and material choice in maintaining the esthetics of resin-matrix ceramics in patients consuming pigmented beverages.

Abstract: Application of MXene-polymer composites in wearable and implantable medical devices requires the development of hydrophilic and biocompatible MXene-polymer hydrogel composites with high electromechanical response, flexibility, and durability. Here, we formulate low weight percentage MXene-hydrogel copolymer inks enabling direct light printing (DLP) of MXene-polyvinyl alcohol (PVA)-polyacrylic acid (PAA)-hydrogel composites. The low wt% MXene-PVA-PAA composites demonstrate high biocompatibility, mechanical flexibility, high sensitivity and high precision for sensing acute bending angles. The sub-millidegree angle resolution and sub-microradian stability of these electromechanical sensors demonstrates their suitability for applications such as high precision tracking of joint movements. In addition, the synthesized MXene membranes show promise for applications in osmotic energy conversion, with a harvested electric power density of 6.79 Wm-2.

Abstract:

Transparent materials are highly desirable for multiple optical devices, composite armours, smartphone screens and can be used as host materials for solid-state lasers. However, achieving transparency in composite materials is challenging due to the difference in refractive indices between the matrix and the fillers. The authors investigate the impact of various factors, including particle size, film thickness, and volume fraction, on the optical properties of epoxy-based nanocomposites. Using Rayleigh scattering theory, they assess the effect of different materials and manufacturing parameters on the transmittance of nanocomposites. Their findings suggest that a theoretical transmittance of over 90% can be achieved by using particle sizes less than 10 nm and film thicknesses less than 1 µm.

Abstract: This work presents a study on the erosive wear behavior of laminated composites, manufactured using the vacuum assisted resin infusion (VARI) method with an epoxy matrix reinforced with glass fibers and modified with SiO2 nanoparticles. Three materials were fabricated with SiO2 nanoparticle concentrations of 0, 1.5, and 3 wt% to evaluate the effect of nanoparticle addition and dispersion on mechanical and microstructural properties, as well as erosion resistance. The results showed that the FG-1.5-SiO2 composite, containing 1.5 wt% SiO2 nanoparticles, exhibited the best nanoparticle dispersion, as evidenced by FTIR, GIXRD, and SEM analyses. This material displayed the lowest surface roughness (Ra = 0.215 μm), the highest Vickers hardness (35.58), and the highest modulus of elasticity (19.66 GPa), indicating an effective load transfer and adequate interfacial interaction. In erosion tests, the FG-1.5-SiO2 material demonstrated the lowest total mass loss (0.0261 mg) and the lowest erosion rate (2.3360E-5 mg/g), representing an approximately 38 % improvement in erosion resistance compared to the reference material without nanoparticles (FG-0-SiO2). Profilometry and SEM analyses confirmed that this composite FG-1.5-SiO2 exhibited less severe erosional damage, with shallower wear depth, characterized by less matrix removal and a stronger fiber-matrix interface. On the other hand, the composite with 3 wt% SiO2 (FG-3-SiO2) showed poor dispersion and agglomeration, resulting in increased roughness, lower mechanical properties, and erosion resistance similar to that of the material without nanoparticle reinforcement. This was attributed to the agglomerates acting as stress concentrators and structural defects that facilitate material detachment.