Search Results (1,450)

Wood biomass ash (WBA) is a by-product from biofuel energy plants. The disposal of this waste is connected with numerous environmental concerns. A more sustainable choice is to recycle it as a raw material for building and construction materials. However, due to its unstable characteristics, its application in alkali-activated materials (AAM) poses a challenge. One issue is the development of the mechanical properties. To improve them, pozzolanic additives, including coal fly ash (CFA), metakaolin (MK), and natural zeolite (NZ), were added at replacement ratios of 10–40%. Calcium hydroxide, sodium hydroxide, and sodium silicate were used together as ternary activators. The samples were cured at 60 °C for the first 24 h and for the remaining 27 days at room temperature. Mechanical behavior, water absorption, and chemical compositions were examined. The results obtained from XRF were compared with the calculation results of the chemical compositions based on the mix design and oxide compositions of the raw materials. The results show that the respective optimum replacement ratios were 30% CFA, 20% MK, and 20% NZ, with the highest compressive strength corresponding to 22.71, 20.53, and 24.33 MPa, and the highest flexural strength of 4.49, 4.32, and 4.21 MPa. NZ was the most effective in AAM, due to the highest Si/Al ratio in the Ca-rich ambient. Then, CFA contributed less, and MK was the least efficient when used in combination with WBA in AAM. The reduction of Ca/Si ratios in the AAM caused by the pozzolanic additives favors the formation of a binder system made of different hydrates and facilitates the strength enhancement when the Ca/Si ratio is lower than 0.35. Full article

This study investigates the deterioration of the thermal and mechanical properties of geopolymer foam concrete (GFC) subjected to accelerated weathering through carbonation, salt fog, and UV radiation. GFC blocks were synthesized using metakaolin as the aluminosilicate precursor, activated with an alkaline solution consisting of 8 M NaOH and sodium silicate (Na₂SiO₃) at a NaOH/Na₂SiO₃ ratio of 0.51 wt.%. A 30% (v/v) H₂O₂ solution served as the foaming agent, and olive oil was used as the surfactant. Accelerated carbonation tests were conducted at 25 ± 3 °C and 40 ± 3 °C, under 60 ± 5% relative humidity and 5% CO₂, with carbonation depth, carbonation percentage, density, porosity, and thermal conductivity evaluated over a 7-day period. In parallel, specimens were exposed to salt fog and UV radiation for 12 weeks in accordance with ASTM B117-19 and ASTM G154-23, respectively. Compressive strength was monitored every week throughout the exposure period. Results show that carbonation temperature governs the type and kinetics of carbonate formation. The carbonation process, at 40 °C for 7 days, increased the density and reduced the porosity of GFC, resulting in a ~48% increase in thermal conductivity. Salt fog exposure led to severe mechanical degradation, with NaCl penetration reducing compressive strength by 69%. In contrast, UV radiation caused only minor deterioration, decreasing compressive strength by up to 7%, likely due to surface-level carbonation. Full article

Background/Objectives: Cancer is among the leading causes of mortality worldwide. In 2022 alone, the global cancer death toll stood at 9.74 million. Projections indicate that this figure will rise to 10.4 million by 2025. Methods: A new series of benzimidazolone-bridged hybrid compounds containing thiophene, furan, oxadiazole, piperazine, and coumarin moieties was synthesized and structurally characterized by ¹H-NMR, ¹³C-NMR (APT), and elemental analysis. Their cytotoxic effects were evaluated by MTT assay against human lung (A549), human breast (MCF-7), and human cervical (HeLa) cancer cell lines, and the non-cancerous HEK293 cell line after 48 h exposure over a concentration range of 0.5–250 µM. IC₅₀ values were determined, and Selectivity Indexes (SI) were calculated using HEK293 as the reference normal cell line. Molecular docking studies were carried out using the Glide XP protocol against VEGFR2 (PDB ID: 4ASD) and CDK4–Cyclin D3 (PDB ID: 7SJ3), with sorafenib and abemaciclib as reference inhibitors. Results: The results of anticancer activity were compared with doxorubicin (IC₅₀ ± SD (µM)/SI: 4.3 ± 0.2/1.20 for A549, 6.4 ± 0.37/0.77 for MCF-7, 3.4 ± 0.19/1.54 for HeLa), a drug used for cancer chemotherapy. The structures of the newly synthesized hybrid compounds were identified by ¹H-NMR, ¹³C-NMR (APT), and elemental analysis data. These hybrid compounds represent a promising class of anticancer agents. Several compounds demonstrated marked and concentration-dependent cytotoxicity across all cancer cell lines, with HeLa cells showing the highest overall sensitivity. The introduction of an oxadiazole ring (compound 7) and coumarin substituents (compounds 12b–12d) markedly improved anticancer activity and selectivity, yielding low-micromolar IC₅₀ values in HeLa cells (10.6–13.6 µM) and high Selectivity Indexes (SI = 2.0–3.63). Compound 6 also exhibited balanced potency across A549, MCF-7, and HeLa cells (IC₅₀ = 28.3–31.2 µM) with SI values ≥ 2.0. Compound 9 showed strong cytotoxicity across all cancer cell lines; its moderate SI values indicate lower discrimination between malignant and non-malignant cells. Taken together, these findings identified compounds 7, 12b–12d, 6, and 12c as the most promising benzimidazolone-based candidates, displaying both potent cytotoxicity and favorable selectivity over non-malignant HEK293 cells. Conclusions: Among the synthesized molecules, the oxadiazole derivative (7) and the coumarin-based hybrids (12b–12d) exhibited the strongest combination of cytotoxic activity and selectivity, reflected by their low IC₅₀ values and high SI ratios. Notably, compound 12c combined strong biological activity with the highest predicted VEGFR2 affinity in the series, highlighting it as a particularly promising scaffold. While compound 9 exhibited excellent docking scores toward both VEGFR2 and CDK4, its lower selectivity suggests a need for further structural refinement. Overall, the biological and computational findings converge to identify these benzimidazolone hybrids as credible lead candidates for future anticancer optimization. Full article

This study evaluated the applicability of the dual drainage model, Hyper Connected–Solution for Urban Flood (HC-SURF), for real-time urban flood forecasting. The model was applied to the extreme rainfall event of August 2022 in the Sillim and Daerim drainage basins in Seoul. Its accuracy and computational efficiency were quantitatively compared with those of two widely used commercial models, the Personal Computer Storm Water Management Model (PC-SWMM) and InfoWorks Integrated Catchment Modelling (ICM). Accuracy was assessed by measuring spatial agreement with observed inundation trace maps using binary indicators, including the Critical Success Index (CSI), Probability of Detection (POD), and False Alarm Ratio (FAR). Computational efficiency was evaluated by comparing simulation times under identical conditions. In terms of accuracy against observations, HC-SURF achieved CSI values ranging from 0.26 to 0.45, with POD values from 0.37 to 0.81 and FAR values from 0.49 to 0.53 across the two basins. In inter-model comparisons, the model showed high hydraulic consistency, demonstrating CSI values between 0.72 and 0.88, POD between 0.82 and 0.99, and FAR between 0.08 and 0.15. In terms of computational efficiency, HC-SURF reduced calculation times by approximately 9% and 44% compared with InfoWorks ICM and PC-SWMM, respectively, for a 48 h simulation. The model also completed a 6 h rainfall simulation in approximately 8 min, meeting the lead time requirements for rapid urban flood forecasting. Overall, these findings show that HC-SURF effectively balances simulation accuracy with computational efficiency, demonstrating its suitability for real-time urban flood forecasting. Full article

This study systematically investigates the key parameters governing the mechanical performance of fly ash-based geopolymer across paste, mortar, and concrete scales. Comprehensive mechanical testing, combined with SEM and MIP analyses, elucidated the relationships between activator composition, pore structure, and strength development. A key innovation is the development of a cross-scale quantitative framework linking mortar strength to concrete compressive strength, enabling preliminary predictive capability across material scales. Grey relational analysis identified curing temperature as the most influential factor, followed by SiO₂/Na₂O and H₂O/Na₂O ratios. Thermal curing accelerates strength development and temperatures of 70~80 °C markedly enhance reaction rates. Both compressive and flexural/splitting tensile strengths increase and then decrease with NaOH concentration or sodium silicate modulus, with optimal performance at 24~26% NaOH and SiO₂/Na₂O ratio of 1.2~1.4, while increasing H₂O/Na₂O reduces strength nearly linearly, constrained by workability. Concrete compressive strength rises with coarse aggregate content up to 60~70% before declining. SEM and MIP confirm that optimal activator formulations produce a dense, homogeneous gel matrix with lower porosity and fewer unreacted particles. Strong square-root correlations between compressive and tensile-related strengths were observed across all material systems. Overall, this work establishes a quantitative foundation for geopolymer mix design and provides actionable guidance for developing high-performance, low-carbon geopolymer concrete. Full article

This study investigated the hierarchical structuring of *BEA zeolite using 0.2 M sodium hydroxide followed by 0.5 M hydrochloric acid (T-NaOH-HCl). Tungsten trioxide (WO₃) was then impregnated at different loadings (5, 10, 15, and 20 wt.%) onto the hierarchized materials (BEA-T). The modified zeolites were subsequently used as catalysts for the dehydration of ethanol (230 and 250 °C) and 1-propanol (230 °C). The hierarchization treatment increased the Si/Al ratio (from 13 to 39), decreased relative crystallinity by 15%, and reduced the average crystal-domain size (from 18 to 10 nm). After the NaOH–HCl treatment (BEA-T), the mesopore area increased by 7%, the mesopore volume by 19%, and the total pore volume by 12%. Conversely, the BET specific surface area and micropore volume decreased, indicating effective hierarchization of the *BEA zeolite. XRD, FT-IR and Raman confirmed the presence of monoclinic WO₃ on the BEA-T surface. MAS NMR analyses of ²⁷Al and ²⁹Si indicated that the T-NaOH-HCl treatment slightly increased the population of tetrahedral Al environments. The high conversion and selectivity from the dehydration of ethanol and 1-propanol can be attributed to a moderate reduction in the acidity of *BEA zeolite and tunned mesoporosity. Based on TON, catalysts with 10% and 20% WO₃ stood out in dehydration tests. Full article

Spectral indices are widely used to assess vegetation fire severity following wildland fires. Although essential, ground-based assessments of how such indices change due to varying fire intensities remain limited, especially with deciduous tree species that exhibit resprouting. In this paper, we evaluate the efficacy of detecting post-fire physiological change and top kill in quaking aspen (Populus tremuloides) saplings using differenced spectral indices. Saplings (n = 64) were burned under controlled conditions over a range of discrete fire intensity levels from 0 to 4.0 MJ m⁻², and reflectance was collected pre-fire and at six post-fire intervals up to 16 weeks. Ten spectral indices (CCI, CSI, MIRBI, NDVIL8, NBR, NBRL8, PRI, SAVI, SW-NIR_ratio, and SW-SW_ratio) were calculated, differenced from pre-fire, and related to the change in net photosynthesis and top kill. Fire intensity most strongly influenced the observed spectral changes at weeks 1–2 post-fire, especially for ΔCSI, ΔCCI, and ΔPRI. Pre- to post-fire change in net photosynthesis was strongly related (Tjur’s R² > 0.5) with ΔCCI, ΔCSI, ΔNBRL8, and the ΔSW–NIR ratio at one week post-fire. Of the spectral indices assessed, ΔCCI and ΔPRI were most effective at predicting top kill. This study illustrates the potential of spectral indices for monitoring vegetation fire severity in deciduous tree species. Full article

The conventional production of electronic-grade, high-purity, spherical silicon dioxide (SiO₂) faces challenges of high raw material costs and poor control over particle morphology. This study presents an alternative route using low-cost, powdered quartz as a starting material. The quartz was first purified by flotation to remove any associated minerals, such as talc. Subsequently, deep purification was achieved through a hydrothermal alkaline process, which leveraged the distinct leaching kinetics of SiO₂ and impurity ions (Al³⁺, Ca²⁺, Fe³⁺) under precisely controlled hydrothermal conditions (10 mL/g liquid-to-solid ratio, 3 mol/L NaOH, 200 °C, 8 h). This step yielded a sodium silicate solution with a purity of 99.999%. Spherical SiO₂ particles were then synthesized from solutions of varying moduli via chemical precipitation. The condensation kinetics of silicate anionic species (Qn) during acidification were investigated, revealing how the Qn distribution governs the final particle size and morphology. The optimal product exhibited excellent characteristics: a sphericity ≥ 0.98, a median particle size (D₅₀) of 400–500 nm, and a narrow particle size distribution (polydispersity index, PDI of 0.178–0.192). These properties surpass the requirements for the QYG-H Type 002 grade specified in the Chinese National Standard GB/T 32661-2016 (“Spherical Silica Powder”) and meet the standard for electronic-grade spherical SiO₂. This work provides a fundamental insight into morphology control and a feasible technical pathway for the value-added utilization of powdered quartz and the production of electronic-grade spherical SiO₂ with a narrow particle size distribution. Full article

The rational design of highly efficient bifunctional SAPO-11 catalysts for hydroisomerization of n-C₁₆ requires unprecedented control over both acidic properties and diffusion characteristics. This work systematically investigates the influence of the SiO₂/Al₂O₃ molar ratio (0.1–0.4) in the initial gel on the physicochemical and catalytic properties of SAPO-11. Using a combination of characterization techniques (XRD, SEM, TEM-SAED, ²⁹Si MAS NMR, and IR-Py), it was established that this parameter serves as a simple tool for crystal engineering. The concentration of Brønsted acid sites and the external surface area demonstrate a non-linear dependency, reaching their maximum at SiO₂/Al₂O₃ = 0.3. Further increase in silicon content reduces both crystallinity and acidity due to the transition to the dominant SM2 + SM3 incorporation mechanism and the formation of silicon islands. Notably, varying the SiO₂/Al₂O₃ ratio enables control over crystal morphology—progressing systematically from truncated cones (SiO₂/Al₂O₃ = 0.1) to flat prismatic platelets (SiO₂/Al₂O₃ = 0.2) and ultimately hierarchical spherical aggregates (SiO₂/Al₂O₃ = 0.4). In n-C₁₆ hydroisomerization, the Pt/SAPO-11(0.2) catalyst demonstrated the highest yield of i-C₁₆ compared to other samples reaching 81%. The platelet morphology ensures a minimal diffusion path (<100 nm), effectively suppressing secondary hydrocracking. This finding underscores that morphology optimization is more critical than maximizing acidity for achieving high selectivity in the context of n-C₁₆ hydroisomerization over Pt/SAPO-11. Full article

The synthesis, phase behavior and semiconductor properties of two novel organosilicon tetramers with dialkyl-substituted [1]benzothieno[3,2-b]benzothiophene (BTBT) moieties, D4-Und-BTBT-Hex and D4-Hex-BTBT-Oct, are described. The synthesis of these molecules was carried out by sequential modification of the BTBT core by carbonyl-containing functional alkyl substituents using the Friedel–Crafts reaction, followed by the reduction in the keto group. The target tetramers, D4-Und-BTBT-Hex and D4-Hex-BTBT-Oct, were obtained by the hydrosilylation reaction between tetraallylsilane and corresponding 1,1,3,3-tetramethyl-1-(ω-(7-alkyl[1]benzothieno[3,2-b]benzothiophen-2-yl)alkyl)disiloxanes. The chemical structure of the compounds obtained was confirmed by NMR ¹H-, ¹³C- and ²⁹Si-spectroscopy, gel permeation chromatography and elemental analysis. Their phase behavior was investigated by differential scanning calorimetry, polarization optical microscopy and X-ray diffraction analysis. It was found that D4-Und-BTBT-Hex shows higher crystallinity at room temperature as compared to D4-Hex-BTBT-Oct, while both molecules possess smectic ordering favorable for active layer formation in organic field-effect transistors (OFETs). The active layers were applied by spin-coating under conditions of a homogeneous thin layer formation with a low content of defects. The devices obtained from D4-Und-BTBT-Hex have demonstrated good semiconductor characteristics in OFETs with a hole mobility up to 3.5 × 10⁻² cm² V⁻¹ s⁻¹, a low threshold voltage and an on/off ratio up to 10⁷. Full article

ZSM-5 zeolites with varying aluminum content were subjected to steam treatments of different severities by adjusting the temperature, duration, and water vapor pressure. The steamed samples were characterized using a range of analytical techniques. A quantitative assessment of the aluminum species—namely, tetrahedrally coordinated framework Al, dislodged framework Al, non-framework pentacoordinated Al, and non-framework hexacoordinated Al—was achieved through a combination of EDX analysis on Cs-exchanged materials and quantitative ²⁷Al MAS NMR spectroscopy, including spectral simulation. Contrary to previous reports, the catalytic activity per framework Al site in unsteamed ZSM-5 increases with aluminum content at low Si/Al ratios, aligning with recently proposed medium effects. Notably, at the point of maximum activity enhancement due to steaming, equivalent amounts (1:1) of framework and dislodged framework Al—both in tetrahedral coordination—are observed. The maximum enhancement factor per framework Al site, for a given material and reaction, remains independent of the specific steaming conditions (temperature, time, and pressure). However, the degree of activity enhancement varies with the type of reaction: it is more pronounced for n-hexane cracking (α-test) than for m-xylene isomerization. This suggests that both catalyst modification and reaction characteristics contribute to the observed steam-induced activity enhancement. A synergistic interaction between Brønsted and Lewis acid sites appears to underpin these effects. One plausible mechanism involves the strengthening of Brønsted acidity in the presence of adjacent Lewis acid sites. This enhancement is expected to be more significant for n-hexane cracking, which demands higher acid strength compared to m-xylene isomerization. In cases of n-hexane cracking, the increased acid strength and the formation of olefins via reactions on Lewis acid sites may act cooperatively. Importantly, the dislodged framework Al species—tetrahedrally coordinated in the hydrated catalyst at ambient temperature and functioning as Lewis acid sites in the dehydrated zeolite under reaction conditions—are directly responsible for the observed enhancement in acid activity. The transformation of framework Al into dislodged framework Al species is reversible, as demonstrated by hydrothermal treatment of the steamed samples at 150–200 °C. Nonetheless, reinsertion of Al into the framework is not fully quantitative: a portion of the dislodged framework Al is irreversibly converted into non-framework penta- and hexacoordinated species during the hydrothermal process. Among these, non-framework pentacoordinate Al species may serve as counterions to balance the lattice charges associated with framework Al. Full article

In the field of enhanced oil recovery in low-permeability reservoirs, the application of nanomaterials has attracted widespread attention. However, conventional nanomaterials exhibit issues such as large particle size and poor dispersion stability. This study selected SiO₂ nanoparticles with a particle size of 10 nm and combined them with 12 types of commonly used oilfield surfactants. After aging at 120 °C for 48 h, using dispersion stability and interfacial tension (IFT) as evaluation criteria, hexadecyltrimethylammonium bromide (CTAB) was ultimately identified as the optimal modifier. The structure and morphology of the SiO₂ particles were characterized in detail using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). The system evaluated the dispersion stability of nanofluids before and after modification, as well as the interfacial properties (IFT reduced to the 10⁻¹ mN/m range) and wettability (oil-wet surfaces reversed to strongly water-wet, with contact angles decreasing to 30°) of nanofluids with different modification degrees. Considering economic factors, the modified nano-SiO₂ system with a ratio of 1:0.5 was selected. Microvisualization experiments revealed that the modified nanoscale system achieves residual oil displacement through three mechanisms: emulsification (reducing residual oil droplet size to enhance mobility), wetting reversal (lowering contact angle to weaken adhesion), and structural separation pressure (counteracting capillary forces to destabilize residual oil). Displacement experiments reveal that in rock cores with permeability ranging from 1 to 100 mD, the modified system exhibits a recovery rate trend that initially increases and then decreases. Nevertheless, it consistently enhances recovery rates, maintaining them above 12%, demonstrating strong application potential. Full article

Background: Frailty is a major barrier to healthy ageing, yet early identification strategies remain limited. The serum creatinine-to-cystatin C ratio (sarcopenia index, SI) has emerged as a cost-effective biomarker of muscle mass and function, while physical activity (PA) is a key protective factor. However, their combined role in predicting frailty is unclear. This study aimed to investigate the independent and joint associations of SI and PA with incident frailty in middle-aged and older adults. Methods: We analyzed 5307 participants aged ≥45 years from the China Health and Retirement Longitudinal Study (CHARLS, 2011–2018). SI was calculated from serum creatinine and cystatin C levels, and PA was assessed using standardized questionnaires. Frailty was defined using a 32-item Frailty Index (FI ≥ 0.25). Cox proportional hazards models estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for the associations of SI and PA with incident frailty, adjusting for sociodemographic and health-related factors. Effect modification by PA was formally tested. Results: Over the follow-up period, 1483 participants developed frailty (27.9%). Higher SI was inversely associated with frailty in a dose–response manner: compared with the lowest quartile, HRs (95% CIs) were 0.84 (0.73–0.97) for Q2, 0.83 (0.72–0.96) for Q3, and 0.69 (0.59–0.82) for Q4 (p-trend < 0.001). Each 10-unit increase in SI corresponded to a 6% lower frailty risk (HR = 0.94, 95% CI: 0.91–0.97). PA significantly modified this relationship (interaction p < 0.05), with the strongest protective effect of SI observed among individuals with low PA, and attenuation at higher PA levels. Conclusions: SI is independently associated with a lower risk of incident frailty, particularly among less physically active individuals. These findings support the potential use of SI as a feasible biomarker for early frailty risk stratification and highlight the importance of integrating biomarker-based screening with lifestyle interventions to prevent frailty. Full article

This study investigates lightning activity and evaluates a near-real-time lightning warning system for the inner Hanoi area, using data collected during 2020–2024 from the Strike Guard (SG) and EFM-100C instruments located in Chuong My, Hanoi, Vietnam. Lightning detection data were incorporated with rainfall and lightning location information from the Vietnam Meteorological and Hydrological Administration (VNMHA) for quality checking. The SG data over the research area revealed clear diurnal and seasonal variations, with lightning most frequent in the late afternoon and two major peaks in June and September corresponding to the summer monsoon. A combined warning method using EFM-100C electric field measurements and SG alert states achieved an average lead time of 15 min, a Probability of Detection (POD) of 82.22%, a Critical Success Index (CSI) of 76.55%, an F1 score of 86.72%, and a False Alarm Ratio (FAR) of 8.26%. These results demonstrate that integrating electric field and optical–electromagnetic measurements can provide effective localized lightning warnings for the urban areas. The approach is cost-efficient, operationally feasible, and particularly valuable for protecting critical infrastructure regions, supporting enhanced lightning safety and disaster mitigation in northern Vietnam. Full article

This paper investigates the predictability of stock returns in the Chinese market through the lens of consumption–wealth dynamics within a broader financial system. We focus on two key state variables derived from modern consumption-based asset pricing models: the ratio of log surplus consumption (scr), from the habit-formation framework, and the log consumption–wealth ratio (cay), from the long-run cointegration framework. Using quarterly data from the CSI 300 index between 2012Q1 and 2018Q4, our system-based analysis reveals a horizon-dependent pattern of predictability. The results show that scr is a strong short-term predictor of excess stock returns, reflecting cyclical changes in risk aversion, whereas cay demonstrates superior predictive power over mid- to long-term horizons, consistent with its role as a proxy for long-run expectations. Interestingly, combining scr and cay does not improve predictive performance, suggesting that the economic mechanisms they capture are distinct rather than complementary in the Chinese market. These findings provide evidence on how interconnected macro-financial variables shape stock return dynamics, highlighting the importance of considering temporal horizons when modeling financial systems. Full article