Search Results (4,072)

The integration of recycled materials into cementitious systems presents a sustainable path to reducing environmental impact in construction. This study investigates the mechanical and durability performance of self-compacting mortars (SCMs) incorporating finely ground mortar waste powder (MWP) as a partial cement substitute, reinforced with aluminum oxide (Al₂O₃) and iron oxide (Fe₂O₃). Eleven mixes were designed with MWP replacing cement at 0–50% by volume. Fresh-state tests showed that slump flow decreased moderately (from 259 mm to 240 mm), while V-funnel times improved (from 10.51 s to 7.01 s), indicating acceptable flowability. The optimum performance was observed in SCM2 (5% MWP + oxides), which achieved 75.62 MPa compressive and 13.74 MPa flexural strength at 28 days, outperforming the control mix. Durability under high temperature and freeze–thaw cycling revealed that oxide-reinforced mixes exhibited superior strength retention, with SCM2 maintaining over 87 MPa after 300 °C exposure and minimal degradation after 100 freeze–thaw cycles. Porosity remained low (16.1%) at optimal replacement levels but increased significantly beyond 25% MWP. The results confirm that low-level MWP replacement, when reinforced with reactive oxides, provides a viable strategy for producing durable, high-performance, and eco-efficient SCMs. Full article

The effect of adding 10% biochar (B) or sludgechar (SL) on the water regime and adsorption properties of soils was tested on composites prepared by mixing two standard soils of loamy and clay type with B or SL in a 90:10 weight ratio. Water-holding capacity was assessed as initial (2 h) and equilibrium (24 h). Water retention time was estimated by evaporation from saturated samples at 20 °C to a constant weight. The composites exhibited a 60–90% increase in water absorption compared to the individual soils, retaining water up to 3–6 days longer than the individual soils. The adsorption properties were tested for cation (Pb²⁺) and anion (Sb(OH)₆⁻) adsorption and for Pb²⁺ and Sb(OH)₆⁻ co-adsorption from model solutions under laboratory conditions. All samples showed higher selectivity for Pb²⁺, with the adsorption efficiency from 40% to 99%. Sb(OH)₆⁻ adsorption achieved a maximum efficiency of only 10%. Pb²⁺ and Sb(OH)₆⁻ co-adsorptions were efficient for Sb(OH)₆⁻ adsorption, reaching efficiency levels above 95%. At prolonged reaction times, the adsorption efficiency elevated by more than 20%. Only 10% wt. addition of biochar or sludgechar enhanced not only the water regime of soils but also their adsorption capacity for ionic contaminants. Full article

The mechanism of separating the small chiral drug molecules on large soft polymers is essential in pharmaceutical science. As a case study, the differentiation mechanism of ibuprofen, (R,S)-2-(4-isobutylphenyl)propanoic acid, with cellulose tris(4-methylbenzoate) (CMB) as the chiral stationary phase (CSP) was investigated by combining the molecular docking simulation and multi-level layered terminal-to-center elongation (ML-T2C-ELG) method. Our results demonstrated that, based on the optimized geometry using the ML-T2C-ELG method, the complexation energy of S-ibuprofen with CMB obtained at B3LYP-D3(BJ)/6-311G(d) level is more negative than that of R-ibuprofen, which is caused by the greater hydrogen bonding and π-π stacking interactions between CMB and S-ibuprofen. The results are in line with the experimental observations of high-performance liquid chromatography (HPLC) that the retention time of S-ibuprofen on CMB is longer than that of R-ibuprofen. Moreover, the ML-T2C-ELG method was found to be valuable for optimizing the geometries of such flexible and large systems, which allows for a more accurate description of interactions between soft polymers and small molecules when coupled with the docking simulation. It is anticipated that this study can provide beneficial insights for future optical resolution mechanisms of other chiral drugs. Full article

Cocoa pod husk (CPH), the principal by-product of cocoa processing, represents an abundant and underutilized source of bioactive phenolics with potential applications in the food and nutraceutical sectors. This study optimized the extraction of catechin, epicatechin, procyanidin B2, and clovamide from CPH (CCN-51 variety) using microwave-assisted extraction (MAE) and evaluated the influence of drying temperature on their retention. A Box–Behnken design within a response surface methodology framework was employed to evaluate the effects of ethanol concentration (0–100%), extraction temperature (50–150 °C), and extraction time (15–60 min) on compound recovery. The phenolic profile was characterized by high-performance liquid chromatography with diode-array detection and electrospray ionization ion trap tandem mass spectrometry. Optimal MAE conditions of 51% ethanol, 104 °C, and 38 min yielded maximum concentrations of clovamide, procyanidin B2, and epicatechin of 3440, 908, and 445 mg/kg dry matter of cocoa pod husk, respectively. Drying studies demonstrated that moderate hot-air temperatures (40–50 °C) preserved the highest phenolic levels. These results underscore the importance of optimizing both extraction and drying conditions to enhance the recovery of phenolic compounds from cocoa processing residues, supporting their potential valorization as antioxidant-rich functional ingredients. Full article

Geopolymer binders are a promising low-carbon substitute for Portland cement, but their behavior in cold climates remains underexplored. This study investigates the influence of sodium nitrite (NaNO₂) on geopolymer properties cured at −10 °C for 28 days. The binders were formulated from bauxite residue, fly ash, and waste glass, and NaNO₂ was added in various dosages as a chemical admixture. The geopolymer was tested for its setting time, compressive strength, and chemical and morphological characterizations. The addition of the 3 wt% NaNO₂ significantly improved the strength retention in the cold environment, with a compressive strength of 40.7 MPa, compared to a geopolymer without an admixture (26.1 MPa). The X-ray diffraction (XRD) analysis confirmed the presence of gismondine, quartz, and FeSiO₃, with NaNO₂ remaining largely unreacted within the matrix. Fourier Transform Infrared Spectroscopy (FTIR) indicated the presence of Si–O–T bonds in the NaNO₂-modified samples, which showed continued geopolymerization at low temperatures. Scanning electron microscopy (SEM) revealed reduced cracking and a denser microstructure with increasing concentrations of NaNO₂. The results indicate that NaNO₂ not only mitigates the adverse effects of subzero curing but also promotes structure development, and hence it is a viable admixture for enhancing the cold weather durability of geopolymer materials. Full article

Preformed porous media (PPM) technology has emerged as a transformative approach to enhance heat and mass transfer in vacuum freeze-drying (VFD) of agricultural and food products. This review systematically analyzes recent advances in PPM research, with particular focus on spray freeze-drying (SFD) as the dominant technique for precision pore architecture control. Empirical studies confirm PPM’s efficacy: drying time reductions of 20–50% versus conventional VFD while improving product quality (e.g., 15% higher ginsenoside retention in ginseng, 90% enzyme activity preservation). Key innovations include gradient porous structures and multi-technology coupling strategies that fundamentally alter transfer mechanisms through: resistance mitigation via interconnected macropores (50–500 μm, 40–90% porosity), pseudo-convection effects enabling 30% faster vapor removal, and radiation enhancement boosting absorption by 40–60% and penetration depth 2–3 times. While inherent VFD limitations (e.g., low thermal conductivity) persist, we identify PPM-specific bottlenecks: precision regulation of pore structures (<5% size deviation), scalable fabrication of gradient architectures, synergy mechanisms in multi-field coupling (e.g., microwave-PPM interactions). The most promising advancements include 3D-printed gradient pores for customized transfer paths, intelligent monitoring-feedback systems, and multiscale modeling bridging pore-scale physics to macroscale kinetics. This review provides both a critical assessment of current progress and a forward-looking perspective to guide future research and industrial adoption of PPM-enhanced VFD. Full article

The transport behavior of particles in tortuous fractures is prevalent in the oil and gas extraction process and has a profound impact on engineering. However, due to a variety of factors, drilling fluid leakage is prone to occur during drilling and completion, and an evaluation system for the influence of meander characteristics on the kinetic properties of particles has not yet been established. To this end, this paper constructs a numerical model based on CFD-DEM numerical simulation to simulate the particle–fluid two-phase flow in the meandering fracture, investigates the mechanism of surface meandering on particle force, particle transport velocity, and particle residence time, and proposes a mathematical method based on meandering for predicting particle transport velocity and particle residence time in the stable transport phase. The results show that the increase in tortuosity makes the force state of particles in the fracture show significant instability and intensifies the interaction between fluid and particles in the fracture; the effect of the tortuous wall intensifies the inhomogeneity of transport velocity, and the perturbation effect of the complex path structure on the x-direction velocity of particles is stronger; and the increase in tortuosity is not conducive to particle retention in the fracture. The results of the study can provide theoretical guidance for reducing the risk of drilling fluid leakage during drilling and completion. Full article

Despite medical advances having made HIV a survivable condition, HIV persists as the 11th leading cause of death among young Black women. Enhancing the quality of care engagement through beneficial patient–provider relationships can close gaps in retention and adherence, enabling long, healthy lives. Using constructivist grounded theory informed by an established framework for patient-centered care in complex cancer settings and insight from local HIV advocates, this work identifies what provider actions retain women in care and why. Through focus groups and interviews, eleven Black women in the Southwestern United States, an understudied population, express that providers who engage them as co-creators in maintaining good health are more likely to retain them. Concurrently, when women are attuned to their own health care and interpersonal needs, they discern which providers are equally committed to their health based upon observed provider actions. These actions, such as listening attentively, taking time, and paying attention to the whole person, in conjunction with women’s motivation and active involvement, create a reciprocal dynamic that increases the likelihood these women will remain virally suppressed. The ideal relationship is one in which the provider empowers and champions women as drivers of their own care. Full article

Utilizing a coupled Computational Fluid Dynamics and Discrete Element Method (CFD-DEM) approach, this study constructs a comprehensive three-dimensional numerical model to simulate particle migration dynamics within rough artificial fractures subjected to the high-energy impact of water inrush. The model explicitly incorporates key governing factors, including intricate fracture wall geometry characterized by the joint roughness coefficient (JRC) and aperture variation, hydraulic pressure gradients representative of inrush events, and polydisperse sand particle sizes. Sophisticated simulations track the complete mobilization, subsequent acceleration, and sustained transport of sand particles driven by the powerful high-pressure flow. The results demonstrate that particle migration trajectories undergo a distinct three-phase kinetic evolution: initial acceleration, intermediate coordination, and final attenuation. This evolution is critically governed by the complex interplay of hydrodynamic shear stress exerted by the fluid flow, frictional resistance at the fracture walls, and dynamic interactions (collisions, contacts) between individual particles. Sensitivity analyses reveal that parameters like fracture roughness exert significant nonlinear control on transport efficiency, with an identified optimal JRC range (14–16) promoting the most effective particle transit. Hydraulic pressure and mean aperture size also exhibit strong, nonlinear regulatory influences. Particle transport manifests through characteristic collective migration patterns, including “overall bulk progression”, processes of “fragmentation followed by reaggregation”, and distinctive “center-stretch-edge-retention” formation. Simultaneously, specific behaviors for individual particles are categorized as navigating the “main shear channel”, experiencing “boundary-disturbance drift”, or becoming trapped as “wall-adhered obstructed” particles. Crucially, a robust multivariate regression model is formulated, integrating these key parameter effects, to quantitatively predict the critical migration time required for 80% of the total particle mass to transit the fracture. This investigation provides fundamental mechanistic insights into the particle–fluid dynamics underpinning hazardous water–sand inrush phenomena, offering valuable theoretical underpinnings for risk assessment and mitigation strategies in deep underground engineering operations. Full article

The application of silicon–carbon (Si/C) composite materials in lithium-ion batteries faces problems regarding volume expansion and surface defects. Although coating is a popular modification scheme in the market, the influence of carbon layer quality on the electrochemical performance of Si/C still needs to be studied. By comparing the carbon layers produced by solid-phase and liquid-phase coating methods, an innovative solid–liquid coating technology was proposed to prepare high-strength and high-stiffness carbon layers, and the effects of different coating processes on the physical, mechanical, and electrochemical properties of the materials were systematically studied. Through physical properties and electrochemical testing, it was found that the solid–liquid coating method (Si/C@Pitch+RGFQ) can form a carbon layer with the least defects and the highest density. Compared with solid-phase coating and liquid-phase coating, its specific surface area (SSA) and carbon increment are the lowest, and the surface carbon content and oxygen content are significantly reduced after solid–liquid coating. Mechanical performance tests show that the Young’s modulus of the carbon layer prepared by this method reaches 30.3 GPa, demonstrating excellent structural strength and elastic deformation ability. The first coulombic efficiency (ICE) of Si/C@Pitch+RGFQ reached 88.17%, the interface impedance (23.2 Ω) was the lowest, and the lithium-ion diffusion coefficient was significantly improved. At a rate of 0.1 C to 2 C, the capacity retention rate is excellent. After one hundred and a half-cell cycles, the remaining capacity is 1420.5 mAh/g, and the capacity retention rate reaches 92.4%. The full-cell test further proves that the material has a capacity retention rate of 82.3% and 81.3% after 1000 cycles at room temperature and high temperature (45 °C), respectively. At the same time, it has good rate performance and high-/low-temperature performance, demonstrating good commercial application potential. The research results provide a key basis for the optimized preparation of the surface carbon layer of Si/C composite materials and promote the practical application of high-performance silicon-based negative electrode materials. Full article

Defining appropriate dietary fiber levels is essential for enhancing the sustainability of feedlot lamb production. Optimal dietary fiber levels can enhance meat yield, improve nutrient retention and utilization, and reduce environmental impact. This study aimed to determine the optimal level of dietary fiber to enhance nutrient intake, digestibility, feeding behavior, and rumen fermentation in feedlot lambs. Five rumen-fistulated Santa Inês male lambs (40 kg, 7 months old) were used in a 5 × 5 Latin square design. Diets contained increasing levels of neutral detergent fiber (NDF): 200, 320, 440, 560, and 680 g/kg dry matter (DM), with each period lasting 21 days (total 105 days). Nutrient intake responded quadratically to NDF levels (p < 0.05). Apparent digestibility was significantly affected (p < 0.05), except for crude protein. Feeding (p = 0.001) and rumination times (p = 0.002) increased linearly, while idling time decreased (p < 0.001). Feeder visits declined (p = 0.002), and idling events followed a quadratic trend. Feeding and rumination efficiencies for DM decreased (p = 0.006 and p = 0.010), while NDF rumination efficiency increased (p = 0.014). The ruminal pH rose (p < 0.001), and propionate decreased (p = 0.019); acetate and butyrate showed quadratic responses. Based on intake, digestibility, and fermentation patterns, dietary NDF should be included at 400 g/kg DM to optimize nutrient utilization and rumen function in confined lambs. Full article

Daphne odora is an evergreen shrub belonging to the Thymelaeaceae family that is widely cultivated as an ornamental garden plant. Its roots, leaves, and flowers have traditionally been used in Chinese medicine to treat pain, skin diseases, and rheumatism. While previous phytochemical studies have reported the presence of phenols, coumarins, biflavonoids, lignans, and daphnane diterpenoids in D. odora, its flowers remain largely unexplored. In the present study, the first comprehensive investigation of daphnane diterpenoids contained in the flower buds and blooming flowers of D. odora was conducted using ultra-high-performance liquid chromatography coupled with Q-Exactive-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Exactive-Orbitrap MS). A total of 30 daphnane diterpenoids were identified, including 12 previously unreported compounds, through detailed analysis of their retention times and MS/MS fragmentation patterns. Comparative profiling revealed that flower buds contained a higher abundance and greater diversity of daphnane diterpenoids than flowers. Furthermore, LC–MS-guided isolation enabled the purification of a novel compound, daphneodorin I (16), and its structure was elucidated through extensive physicochemical and spectroscopic analyses. Compound 16 represents the first daphnane diterpenoid with a Z-configured phenolic acyl moiety isolated from plants of the Thymelaeaceae family. Full article

This study analyzed shoreline evolution (2000–2024) at Dalian World Peace Park’s sandy tourist beach using GEE, CoastSat, and DSAS. At the same time, combined with the grain size analysis of beach sediments before and after typhoons, the impact of extreme events on the shoreline line changes was explored. The DSAS shows a spatial differentiation pattern of the southern shoreline retreat trend zone, the central shoreline dynamic balance trend zone and the northern shoreline advance trend zone. The 2008 reclamation project altered hydrodynamics, creating an artificial headland effect that triggered significant northern shoreline advancement (max 74.16 m) and southern retreat (27.14 m), demonstrating unforeseen long-term trade-offs of large-scale interventions. Subsequent cobble structures, acting as a nature-based solution, enhanced sediment retention and wave energy refraction, promoting dynamic equilibrium and shoreline resilience. However, the 2017 double typhoon caused instantaneous retreat with finer, poorly sorted sediment, highlighting persistent vulnerability to extreme events. This study underscores the critical need for adaptive management within a sustainable shoreline development framework. Full article

This study examines the impact of catchment characteristics and design on the performance of urban lakes in terms of water quality and stormwater harvesting potential. Two urban lake systems in Western Sydney, Australia, were selected for comparison: Wattle Grove Lake, a standalone constructed lake, and Woodcroft Lake, part of an integrated wetland–lake system. Both systems receive runoff from surrounding residential catchments of differing sizes and land uses. Over a one-year period, continuous monitoring was conducted to evaluate water quality parameters, including turbidity, total suspended solids (TSS), nutrients (total nitrogen and total phosphorus), pH, dissolved oxygen, and biochemical oxygen demand. The results reveal that the lake with an integrated wetland significantly outperformed the standalone lake in terms of water quality, particularly in terms of turbidity and total suspended solids (TSS), achieving up to 70% reduction in TSS at the outlet compared to the inlet. The wetland served as an effective pre-treatment system, reducing pollutant loads before water entered the lake. Despite this, nutrient concentrations in both systems remained above the thresholds set by the Australian and New Zealand Environment and Conservation Council (ANZECC) Guidelines (2000), indicating persistent challenges in nutrient retention. Notably, the larger catchment area and shallow depth of Wattle Grove Lake likely contributed to higher turbidity and nutrient levels, resulting from sediment resuspension and algal growth. Hydrological modelling using the Model for Urban Stormwater Improvement Conceptualisation (MUSIC) software (version 6) complemented the field data and highlighted the influence of catchment size, hydraulic retention time, and lake depth on pollutant removal efficiency. While both systems serve important environmental and recreational functions, the integrated wetland–lake system at Woodcroft demonstrated greater potential for safe stormwater harvesting and reuse within urban settings. The findings from the study offer practical insights for urban stormwater management and inform future designs that enhance resilience and water reuse potential in growing cities. Full article

This research examines the factors influencing drop out among adult college students. As the traditional-age student population (ages 19–24) declines, the older, part-time, adult learners have emerged as a critical enrollment demographic for higher education institutions. These learners often pursue higher education for career advancement, re-skilling, or re-employment. However, many encounter difficulties in sustaining their academic engagement due to low motivation, limited basic learning skills, or external constraints. Despite the growing presence of adult learners in Korean universities, limited research has analyzed drop-out factors within this specific context. To address this gap, this study applies Bean and Metzner’s nontraditional undergraduate student attrition model, using data from the Korean Educational Longitudinal Study (KELS). It investigates how background characteristics, academic variables, environmental factors, and academic and psychological outcomes influence the drop out of adult learners. The findings reveal that academic variables significantly impact drop-out intentions, while student engagement and social integration show minimal effects. These results offer valuable theoretical insights and practical implications for enhancing adult learner retention in higher education. Full article