Abstract This study investigated the strength development of alkali-activated cements (AACs) synthesized from lime kiln dust (LKD) as a novel high-calcium precursor. The experimental program evaluated soft- and hard-burn LKDs, alone and blended with high-calcium fly ash (HCFA), under ambient and heat-curing conditions (50°C–70°C). X-ray fluorescence (XRF) and X-ray diffraction (XRD) analyses characterized the chemical composition and phase assemblages influencing strength evolution. Under ambient curing, soft-burn LKD exhibited higher reactivity and compressive strength ( ≈ 6 – 7 MPa at 28 days) than hard-burn LKD ( ≈ 0.2 – 0.6 MPa ). Optimum activation occurred at 8 M NaOH for soft-burn and 10 M for hard-burn LKD. Incorporating HCFA markedly enhanced performance, with a 30 ∶ 70 LKD-to-HCFA blend achieving ≈ 20 – 25 MPa , providing an effective balance between strength and sustainability. At 60°C—the optimal curing temperature—soft-burn and hard-burn LKD AACs attained 9–12 and 2.5–3 MPa, respectively, confirming the critical role of temperature in accelerating polymerization. The findings demonstrate that LKD-based AACs, particularly when combined with HCFA, offer a promising low-carbon binder for precast and accelerated construction applications.
Rapid industrialization and coastal development have driven the widespread accumulation of heavy metals (HMs) in marine environments, particularly in sediments and surrounding waters. Heavy metal contamination poses a significant threat to benthic ecosystems and coastal environmental health, highlighting the need for a better understanding of their toxic effects on marine organisms. Perinereis linea is a sediment-dwelling marine polychaete recognized as a sensitive bioindicator of coastal environmental conditions. Through its burrowing activity, P. linea contributes to sediment bioturbation, promoting the mineralization and decomposition of organic matter and supporting the health and stability of benthic ecosystems. Despite its ecological importance, few studies have investigated P. linea as a potential model organism for toxicity assessment, particularly in terms of behavioral responses. In this study, we evaluated the potential of P. linea as a marine model for assessing the behavioral toxicity of HMs using the customized behavioral analysis platform. Behavioral screening of 23 HMs revealed significant locomotor impairments induced by most of the tested metals, characterized by reduced average speed and rapid movement time ratio, increased freezing behavior, and altered movement complexity. PCA and heatmap further identified distinct behavioral fingerprints among the tested metals, with copper exhibiting the strongest behavioral toxicity. Subsequent dose–response experiments demonstrated that copper exposure (1–1000 ppb) significantly reduced locomotor activity and fractal dimension, indicating impaired movement complexity. Co-exposure with chelating agents, including citric acid, chitosan, tannic acid, and sodium alginate, partially restored normal behavioral patterns. Furthermore, transcriptomic findings provided preliminary insights into the potential molecular mechanism underlying HM-induced effects in P. linea. However, given the limited biological replication, the transcriptomic findings should be considered exploratory and interpreted with caution. Collectively, these findings demonstrate the potential of P. linea as a promising marine model organism for behavioral toxicity assessment and environmental monitoring of metal contamination in marine ecosystems.
Aims To fabricate 3-dimensional (3D)-printed resorbable poly(lactic-co-glycolic acid) (PLGA) membranes for guided bone regeneration (GBR). Physical and biological properties of the membranes with varying lactic acid (LA)-to-glycolic acid (GA) ratios were evaluated to determine the optimal PLGA composition for membrane production. Materials and Methods PLGA membranes were fabricated using a 3D printer and categorised into 3 groups: Group A (50:50), Group B (70:30) and Group C (85:15). The membranes’ microarchitecture was examined using a scanning electron microscope (SEM), and their surface wettability, mechanical properties and degradation behaviours were evaluated. Crystalline structures were analysed using an X-ray diffractometer (XRD), and thermal properties were assessed with differential scanning calorimetry (DSC). Fibroblast and osteoblast viability and proliferation on the membranes were measured using SEM, fluorescein diacetate staining and PrestoBlue assay. Osteogenic differentiation was determined through alkaline phosphatase (ALP) and alizarin red (AR) staining. Results SEM images revealed distinct microscopic characteristics of the membranes: rough upper and smooth lower surfaces. Furthermore, greater amounts of LA resulted in high melting temperatures and increased crystallinity in the PLGA membranes. All membranes displayed hydrophilic surfaces, with water contact angles below 90 degrees. Group C membranes exhibited the greatest mechanical strength, whereas group A degraded faster and generated more acidic by-products than the other groups. Osteoblasts and fibroblasts that were seeded on all membrane groups proliferated during the first week. By day 14, only Group C showed continued cell growth, whereas cell growth declined in the others. Group C also demonstrated superior osteogenic differentiation after 21 days. All membranes were effective in inhibiting the penetration of fibroblasts through their structure. Conclusion Overall, the 85:15 (LA:GA) PLGA membrane demonstrated key properties required for GBR, including adequate strength, suitable degradation behaviour and biocompatibility.
Eu3+-doped alkali calcium alumino phosphate oxide (OD) and oxyfluoride (OF) glasses were successfully fabricated using the conventional melt-quenching route. Comparative analyses were performed between the two systems to evaluate their physical, optical, photoluminescence and X-ray induced luminescence properties. The OD glass exhibited higher density and refractive index compared to the OF glass, indicating a more compact glass network. However, the molar volume of the OD was lower than that of the OF due to the larger free volume generated by fluoride incorporation. Based on the absorption spectra, both glass systems exhibited almost identical spectral profiles with minor variations in absorbance intensity. In the photoluminescence study, both glass systems exhibited strong red emission at around 612 nm (5D0 -> 7F2 transition) under 394 nm excitation. The OF glass exhibited a higher emission intensity than the OD glass, primarily due to the lower concentration of hydroxyl groups that act as non-radiative quenching centers. Both glass systems exhibited a reddish-orange emission, in good agreement with the CIE 1931 chromaticity coordinates. The X-ray-induced luminescence exhibited a spectral pattern comparable to that of photoluminescence, while differing in excitation source and luminescence mechanism. The integrated scintillation efficiencies of both glass systems were derived from the peak areas of their X-ray-induced luminescence spectra and compared with that of a Bi4Ge3O12 (BGO) crystal to evaluate their relative scintillation performance. The glasses were successfully imaged under X-ray excitation, confirming their strong potential as optical probes for medical imaging applications.
This paper presents an efficient stabilized leapfrog finite difference scheme for the ternary Allen-Cahn equations that achieves both computational efficiency and rigorous structure preservation. The scheme treats the nonlinear reaction terms explicitly at the middle time level, yielding a fully linear and decoupled system with a time-independent coefficient matrix. A stabilization technique is incorporated to guarantee the discrete maximum bound principle and energy dissipation. The method is uniquely solvable, and optimal convergence is established in the L infinity norm. Extensive numerical experiments in two-and three-dimensional settings confirm the theoretical results and demonstrate stable long-time performance compared with existing linear schemes.
