Search Results (453)

This study presents an experimental investigation of the influence of dopant type and calcination temperature on BaTiO₃-based piezoceramics synthesized by a solid-state calcination process. The effects of Mn, Nb, La, and Ce dopants on the structural, morphological, and piezoelectric characteristics of powders calcined at 1000 °C and 1100 °C were systematically evaluated. In addition, two co-doped BaTiO₃ compositions, namely Mn–Nb and La–Nb, calcined at 1000 °C, were investigated in order to assess the combined effect of acceptor–donor and donor–donor doping strategies on microstructural evolution and structural stability. The synthesized powders were characterized by scanning electron microscopy (SEM), particle size analysis, energy-dispersive X-ray spectroscopy (EDS), elemental mapping, and X-ray diffraction (XRD), in comparison with a commercial BaTiO₃ reference powder. The piezoelectric response was assessed by correlating the structural modifications induced by doping with the estimated piezoelectric coefficient d₃₃, calculated as a function of the tetragonality ratio (c/a) and further correlated with the crystallite size. The results reveal significant variations in grain growth, dopant distribution, and crystallographic stability, highlighting the critical role of dopant chemistry and calcination temperature in tailoring the functional properties of BaTiO₃ for piezoelectric applications. Full article

Moderate thermal exposure can significantly influence the mechanical behavior of volcanic rocks by inducing microcrack development and altering crack network characteristics. However, quantifying such damage processes remains challenging when relying solely on conventional mechanical parameters. In this study, the evolution of crack network complexity in andesite and andesitic–basaltic rocks subjected to moderate thermal exposure (200 °C) is investigated using fractal analysis integrated with mechanical and mineralogical observations. Six core specimens were tested under uniaxial compression, including three natural specimens and three specimens thermally treated at 200 °C prior to loading. After failure, crack surfaces were digitized and fractal dimensions (D) were calculated using the box-counting method. Petrographic observations and X-ray powder diffraction (XRPD) analyses were conducted to characterize the mineralogical composition and microstructural features controlling crack development. The results indicate that thermal exposure primarily reduces rock stiffness rather than peak strength. While the uniaxial compressive strength (UCS) of two specimens remains nearly unchanged after heating, the elastic modulus (E) decreases in all thermally treated specimens. Mineralogical observations reveal a heterogeneous volcanic fabric dominated by plagioclase and pyroxene within a fine-grained groundmass, with secondary calcite phases occurring in veins and pocket fillings. Fractal analysis shows generally lower D values in thermally treated specimens, suggesting crack redistribution and coalescence rather than increased network complexity, consistent with the observed reduction in stiffness and a tendency toward more ductile deformation behavior. Full article

The increasing incidence of multidrug-resistant bacteria has generated an urgent need for innovative antimicrobial materials that inhibit microbial growth through physical and chemical surface interactions, as opposed to traditional biochemical methods. In this work, we synthesized a composite of graphene oxide (GO), single-layer graphene (SLG), and delaminated MXene (d-MXene) by an ultrasonication-assisted technique. The synthesized materials were characterized using powder X-ray diffraction (PXRD), Field-Emission Scanning Electron Microscopy (FE-SEM), and Energy-Dispersive Spectroscopy (EDS) with elemental mapping to examine the structure and morphology of the GO/SLG/d-MXene composite. Antimicrobial activity was evaluated against E. coli using the optical density method. The GO/SLG/d-MXene composite exhibited superior antibacterial activity compared to GO, SLG, and d-MXene. These results indicate that the GO/SLG/d-MXene composite may serve as a promising antibacterial material. These nanomaterials may be further explored for surface-related antimicrobial applications in healthcare, sanitation, and environmental settings such as coatings for medical devices, disinfectant surfaces in hospitals, and treatment of contaminated water sources. Full article

Background/Objectives: This study aimed to develop bilayer tablets using hot-melt pneumatic extrusion (HMPE)-based 3D printing for the integrated treatment of allergic rhinitis and asthma. The formulation combined levocetirizine dihydrochloride (immediate release) and montelukast sodium (delayed release) within a single dosage form to provide a sequential-release formulation strategy relevant to the intended pharmacological roles of the two drugs. Distinct polymer matrices were selected for each drug layer to ensure mechanical robustness, stability, and appropriate release characteristics. Methods: The printed tablets were systematically characterized by mechanical testing, differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and in vitro dissolution. Drug content uniformity was evaluated in accordance with USP <905>. Results: The tablets satisfied USP standards for content uniformity and exhibited sufficient mechanical strength for handling and packaging. DSC and PXRD analyses indicated amorphization of levocetirizine within the polymer matrix, while the amorphous state of the raw montelukast used in this study was retained after printing. In vitro dissolution tests demonstrated immediate release of levocetirizine in acidic medium (pH 1.2) and delayed release of montelukast at intestinal pH (6.8), thereby achieving the intended dual-phase release profile. Conclusions: These findings demonstrate the feasibility of fabricating an HMPE-based 3D-printed bilayer tablet integrating immediate-release levocetirizine and delayed-release montelukast, with reproducible dual-phase release and drug-specific solid-state and performance characteristics within a single oral dosage form. Full article

This study investigates the preparation and performance of ultra-high-performance concrete (UHPC) incorporating manufactured sand as a full replacement for quartz sand. The mix design was optimized by integrating the compressible packing model (CPM) with an orthogonal experimental design. The influence of stone powder content in manufactured sand—0, 5, 10, and 15% by mass of fine aggregate—on fresh-state fluidity and 7d-mechanical properties was systematically evaluated. Hydration products and microstructural features were analyzed using X-ray diffraction (XRD), scanning electron microscope (SEM), and mercury intrusion porosimetry (MIP). Results show that the manufactured sand-based UHPC achieved a fresh-state fluidity of 185 mm and a 7-day compressive strength of 152.4 MPa. Both fluidity and compressive strength exhibited a unimodal trend with increasing stone powder content, reaching maxima at 10%. Microstructural analysis revealed intimate interfacial bonding between unhydrated particles and calcium silicate hydrate (C–S–H) gel; notably, the UHPC matrix with 10% stone powder displayed the densest microstructure. MIP results further demonstrated that an optimal stone powder content effectively reduced total porosity, with the lowest overall porosity and the highest volume fractions of harmless (≤20 nm) and less harmful (20–100 nm) pores observed at 10%. These microstructural refinements collectively underpin the superior mechanical performance of manufactured sand-based UHPC. Full article

Interest in non-centrosymmetric crystalline materials exhibiting second harmonic generation (SHG) has increased due to their potential applications in optical sensing and biosensing. Saccharide-based metal complexes are particularly attractive systems, as chiral sugars can promote non-centrosymmetric crystal packing. In this work, a new lanthanum–β-d-fructose compound, [La(C₆H₁₂O₆)(H₂O)₅]Cl₃ (LaFRUCl), was synthesized using a simple and low-cost method and characterized by single-crystal X-ray diffraction. The compound crystallizes in the orthorhombic space group P2₁2₁2₁ and consists of infinite (La³⁺–fructose)_n chains extending along the [001] direction, forming a one-dimensional Metal–Organic Framework. The nonlinear optical response was evaluated using the Kurtz–Perry powder technique with a Nd:YAG laser (1064 nm) and compared to a sucrose reference. The measured SHG efficiency is comparable to that of previously reported alkaline earth metal–sugar analogs. While the compound’s SHG emission is significant, evaluation of its structural stability under aqueous or physiological conditions is be required before considering biological applications. Full article

This study investigates the long-term resistance of an environmentally friendly composite made from a blend of local Ordinary Portland Cement (OPC) and ground granite waste powder (G). The composite was subjected to complete static immersion for up to twenty-four weeks in three types of water: potable water, groundwater, and seawater. The experimental work evaluated the effects of exposure to these three water types on various characteristics of the granite–cement composite (GCC), including compressive strength, mass gain, portlandite [CH] content, bulk density (D), total porosity (p), compactness, water absorption (A), and pH of the immersing media. Additionally, scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal analysis (TGA and DTA) were used to investigate how exposure to the three water environments altered the internal microstructure of the hydration phases of the composite over the twenty-four-week period. This systematic approach provides valuable insights into the variations that may occur in solid hydration outcomes and their sustainability in flooding scenarios. The data obtained from these analyses revealed that the granite–cement composite exhibits acceptable thermal resistance and endurance to deterioration in aquatic environments. The cement formulation contains 20% by mass of ground granite waste powder, with a water-to-cement ratio of 35%. After 24 weeks of complete static immersion, the composite achieved compressive strength values close to 24 MPa. Solidifying radioactive waste in cement–granite is a newly developed method that improves sustainability by formulating a more stable, durable, cost-effective, and less hazardous waste form. Therefore, the granite–ordinary cement composite being studied is recommended as an inert matrix for solidifying and stabilizing certain categories of radioactive waste. Full article

The rapid development of the lithium battery industry resulted in a large accumulation of spodumene mining residue (SMR). This paper explored the feasibility of using SMR as mineral admixtures in cement mortar. The properties of cement mortar, including flexural strength, compressive strength, fluidity, hydration characteristics, and durability, were studied. The interaction mechanism between SMR and cement mortar had been explored using the Dinger–Funk model, isothermal calorimetry, X-Ray Diffraction (XRD), fourier Transform Infrared Spectroscopy (FTIR), and thermogravimetry (TG) methods. Additionally, the environmental impact of cement mortar was quantitatively evaluated by the life cycle assessment method. The results showed that, while the dosage of SMR was no more than 20 wt.% replaced cement, the flexural strength, compressive strength, and anti-carbonation and sulfate corrosion resistance properties of S2 and S3 cement mortar were similar to that of the blank group. After curing for 28 d, the compressive strength of S1, S2, and S3 were 44.2 MPa, 43.15 MPa, and 40.32 MPa, respectively. SMR powder could improve the workability and reduce the cumulative hydration heat of cement mortar, which confirmed its application potential in large-volume concrete projects. The appropriate content of SMR incorporation into cement mortar could improve the structure and properties of cement-based materials through particle filling, the induced nucleation effect, and the pozzolanic effect. In addition, the utilization of SMR reduced the environmental emissions and resource consumption of cement-based materials. Using 1 m³ cement mortar as an example, for every 10 wt.% increase in SMR powder replacing cement, the energy consumption, the emissions of CO₂, CO, C_xH_y, NO_x, SO₂, dust, and resource consumption of cement mortar were decreased by approximately 342 MJ, 40 kg, 8.1 g, 5.55 g, 88.3 g, 5.24 g, 1.80 kg, and 74.3 kg, respectively. The research findings of this paper are expected to promote the resource utilization of SMR and reduce the carbon emissions of the building materials industry. Full article

The increasing threat of bacterial infections and the limitations of conventional antibiotics have intensified the search for innovative antimicrobial substances. This study investigates a heterostructure nanomaterial of graphene and MXene designed to efficiently inhibit bacterial growth. The graphene–MXene heterostructure was prepared via eco-friendly and non-hazardous ultrasonication to ensure uniform dispersion and interfacial interaction between the 2D components. Powder X-ray diffraction (PXRD), Fourier-Transform Infrared Spectroscopy (FTIR), and High-Resolution Transmission Electron Microscopy (HR-TEM) confirmed the successful integration of the graphene-and-MXene-based heterostructure. Antibacterial activity has assessed using colony-forming unit (CFU) quantification against Escherichia coli (E. coli). Substantially reduced CFU counts and significant inhibition of bacterial growth are observed in the presence of graphene–MXene heterostructure compared to pristine materials. This study opens new avenues for the future development of 2D heterostructures engineered for microbial resistance under diverse conditions. Thus, the design of graphene–MXene heterostructure is a promising strategy for next-generation antimicrobial applications. Full article

Valorizing construction and demolition waste (CDW) via alkaline activation enables low-carbon binders. This study assesses binary geopolymers formulated with recycled brick powder (PLR) and recycled concrete powder (PCR) in seven precursor ratios (0–100% PCR), activated with a ternary NaOH/Na₂SiO₃/KOH solution (silicate modulus M_s ≈ 3.2) at L/B = 0.15, and cured for 7, 14, and 28 days. Compressive strength (fc), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS) were used to link microstructure–phases–properties. A local maximum in fc at ~30% PCR (16.2 MPa at 28 d) was observed versus 0% PCR (14.2 MPa) and ≥50% PCR (13.8 → 10.1 MPa at 28 d). XRD indicated a reduction in inherited crystalline phases and an increased amorphous fraction at ~30% PCR; FTIR (normalized peak position and FWHM of the T–O–Si band, not absolute intensity) suggested higher network extension; SEM-EDS (local/semiquantitative) showed a moderate rise in Ca that supports C-A-S-H domains bridging the N-A-S-H network. At a high PCR, excess Ca simplified mineralogy (quartz/portlandite dominance), promoted competitive routes (C-S-H/carbonation), reintroduced microdefects, and reduced fc. A theoretical oxide balance per mix identified a compositional window where Ca/(Si + Al) ≈ 0.35–0.45 coincides with the mechanical optimum and with XRD/FTIR tracers. Overall, a ~30% PCR window maximizes co-reticulation of N-A-S-H/C-A-S-H and densification without compromising aluminosilicate continuity, providing transferrable design and process-control criteria for CDW-based geopolymer binders. Full article

Proton exchange membranes (PEMs) are essential for fuel cells, yet conventional materials like Nafion suffer from humidity dependence and limited thermal stability. This study introduces sulfonated phenylene-bridged periodic mesoporous organosilicas (PMOs) as promising inorganic–organic hybrid PEMs, synthesized via surfactant-templating with varying alkyl chain lengths for different mesopore sizes. Post-synthetic functionalization involves nitration of phenylene moieties, reduction to amines, and ring-opening of propane or butane sultones to graft sulfonic acid groups via flexible spacers, achieving homogeneous distribution along pore walls. Post-functionalization is confirmed by powder X-ray diffraction (PXRD), revealing preserved 2D hexagonal p6mm ordering and phenylene stacking. N₂ physisorption shows type IV isotherms with reduced pore volumes and pore sizes. ¹H NMR is used to quantify functionalization degrees. Impedance spectroscopy on pressed pellets demonstrates proton conductivities up to 2 × 10⁻³ S cm⁻¹ at 30 °C and 90% RH, depending on the functionalization degree, confirming sulfonic acid-mediated conduction. Full article

This study investigated the effects of different types and ratios of plasticizers on the fabrication and properties of hot-melt-extruded filaments and fused deposition modeling (FDM) three-dimensional printed tablets containing theophylline (THEO). Polyethylene glycol (PEG) 1500 and stearic acid (SA) were used as plasticizers to prepare THEO-loaded filaments in a hydroxypropyl cellulose matrix via hot melt extrusion (HME), which were subsequently fabricated into tablets using an FDM 3D printer. The physicochemical properties of the filaments and printed tablets were evaluated using scanning electron microscopy, X-ray powder diffraction, and Fourier transform infrared spectroscopy. Drug release behavior was assessed using four tablet formulations (T1–T4) with different plasticizer types and ratios. All fabricated filaments exhibited sufficient hardness and flexibility for reliable 3D printing, and solid-state analyses confirmed partial molecular dispersion of THEO within the polymer matrix. In dissolution studies, PEG-containing formulations showed faster drug release than SA-based formulations, while all 3D-printed tablets achieved approximately 80% drug release within 6 h. Overall, this study demonstrates that the combined use of HME and FDM-based 3D printing, together with rational plasticizer selection, enables the development of personalized pharmaceutical tablets with tunable immediate and sustained drug release profiles. Full article

The widespread occurrence of pharmaceutical residues in aquatic environments necessitates the development of advanced porous materials for efficient remediation. This study investigates the adsorption mechanisms of ibuprofen and atenolol within the high-silica zeolite Y. Batch adsorption experiments demonstrated significant uptake, with loading capacities of 191.6 mg/g for ibuprofen and 273.0 mg/g for atenolol, confirming the material’s effectiveness. Using a combination of neutron and X-ray powder diffraction, complemented by Rietveld refinement and simulated annealing algorithms, we achieved the exact localization of the guest molecules. While the pristine zeolite maintains cubic symmetry $Fd\overline{3}$, the incorporation of pharmaceutical molecules induces significant residual nuclear density and anisotropic lattice distortions. To accurately model these perturbations, a systematic symmetry reduction to the acentric triclinic space group F1 was implemented. This approach enabled an ab initio refinement of the structure, revealing that drug uptake of each guest is governed by distinct chemical drivers. Ibuprofen is stabilized via steric confinement and long-range dispersive interactions. In contrast, atenolol stability is governed by electrostatic charge compensation within the zeolitic voids. Our results suggest that the final adsorption geometry is dictated by the spatial orientation of functional groups and host–guest proximity rather than molecular chirality. These results provide a microscopic model describing the fundamental host–guest interactions in FAU zeolites. This structural understanding is an essential step towards the potential use of zeolitic materials in environmental remediation and complex guest sequestration. Full article

This study investigates phase formation in the Sr–Zn–Eu³⁺ orthophosphate system, focusing on double- and triple-phosphates. The isomorphisms and phase formation in Sr_3–1.5xEu_1+x(PO₄)₃, Sr_9–1.5xZn_1.5Eu_x(PO₄)₇, Sr_9.5–1.5xZnEu_x(PO₄)₇, Sr_3–xZn_xEu(PO₄)₃, and Sr_3–xZn_x(PO₄)₂ series were studied using powder X-ray diffraction and Rietveld refinement. A ternary phase diagram was constructed, identifying concentration limits for pure phases and multi-phase regions as well as areas of stabilization of strontiowhitlockite-, palmierite-, eulytite-, and strontiohurlbutite-type phases. The combinatorial complexity of Sr-based phosphates is discussed. The β-Sr₃(PO₄)₂ isostructural to whitlockite was found to exhibit the highest isomorphic capacity for Eu³⁺ cations, which is advantageous for its application as a red-emitting phosphor. Photoluminescence properties were studied, and analyzed based on structural data. Photoluminescence studies confirmed intense red-emission dominated by the ⁵D₀ → ⁷F₂ transition of Eu³⁺, with the β-Sr₃(PO₄)₂-based phosphor showing the highest emission intensity. Full article

Cerium (Ce³⁺)-doped gadolinium orthoborate (GdBO₃) phosphor powders were synthesized via an aqueous sol–gel route, with systematic variation in solution pH (2, 5, and 8) and annealing temperature (600–1200 °C, in 100 °C increments) to investigate their influence on structural, optical, and scintillation properties. The materials were comprehensively characterized using thermogravimetric and differential thermal analysis (TG–DTA) to assess thermal behavior, X-ray diffraction (XRD) for crystal structure determination, Fourier-transform infrared spectroscopy (FTIR) for vibrational analysis, and both photoluminescence (PL) and radioluminescence (RL) spectroscopies to evaluate optical and scintillation performance. All samples crystallized in the hexagonal GdBO₃ vaterite phase (space group P6₃/mcm). The PL and RL emission spectra were consistent with the Ce³⁺ 5d–4f transitions, and scintillation yields under X-ray excitation were quantified relative to a standard Gadox phosphor. A decrease in photoluminescence quantum yield (PLQY) was observed at annealing temperatures above 800 °C, which is attributed to the incorporation of Ce³⁺ into the host lattice. Scintillation decay profiles were recorded, enabling extraction of timing kinetics parameters. Overall, the results reveal clear correlations between synthesis conditions, structural evolution, and luminescence behavior, providing a rational basis for the optimization of Ce³⁺-doped GdBO₃ phosphors for scintillation applications. Full article