Search Results (1,050)

To enhance the application value of sand washing residue mud (SWRM) and mitigate its adverse environmental impacts, this study focuses on the resource utilization of SWRM. The research employed a combined mechanical–thermal activation method to enhance the activity of SWRM and utilized the mixed optimal design module to design and optimize the mixing ratio of SWRM-based LC3 cement. The results showed that within a ball-milling time range of 3–9 min, as the ball-milling time increased, the specific surface area increased, the median particle size D₅₀ decreased, and the particle size was mainly concentrated within the range of 0.1–30 μm; the specific surface area of the washed sand residue after 3 min of grinding reached 1080 m²/kg, with D₅₀ being 3.50 μm, which met the requirements for making cementitious materials. After thermal activation at temperatures ranging from 450 °C to 950 °C for the 3 min ground SWRM, the 28 d activity index showed a trend of increasing first and then decreasing with the increase in calcination temperature, and the 28 d activity index reached the maximum of 79.3% at a calcination temperature of 650 °C. The optimal mixing ratio of the AC70 group’s SWRM-based LC3 cement obtained through the mixing design was: cement clinker 66.5%, desulfurized gypsum 3.5%, activated SWRM 15%, and limestone powder (LP) 15%. The 28 d compressive strength of the AC70 group’s SWRM-based LC3 cement was 34.1 MPa, with initial setting and final setting times of 170 min and 240 min respectively, and the volume stability was qualified. The microscopic test results indicated that under the synergistic effect of alkali and salt, the silicate and aluminosilicate tetrahedral structures in the active sand-washed mud (ASWRM) decomposed, forming a C-(A)-S-H network structure, which was the main source of strength for the SWRM-based LC3 cement in the later stage. The ecological benefit calculation and analysis showed that compared with ordinary Portland cement of the same grade, the AC70 group’s SWRM-based LC3 cement had a 27.6% reduction in implicit energy consumption, a 44.1% reduction in carbon emissions, and a 25% reduction in cost. This study provides an innovative approach for the high value-added resource utilization of SWRM. Full article

Rare-earth-based permanent magnets are key elements for today’s technologies. Their recycling is crucial for securing the supply of critical raw materials and ensuring a sustainable circular economy in magnet production. In this study, hydrogen decrepitated NdFeB powders recovered from end-of-life magnets were processed using planetary ball milling to obtain powders suitable for recycled magnet production. The magnets were sourced from a wind turbine, scooter motor, and ring magnet, and exhibit different compositions and properties. The structural, morphological, and magnetic properties of the hydrogenated and ball-milled powders were investigated considering the effects of the milling time and ball diameters. Submicron-sized powders were achieved within 10 min with 5 mm balls, while longer milling times were required to obtain similar particle size reduction with 10 mm balls. Milling resulted in structural damage to the hydrogenated powders. Furthermore, although milling decreased the magnetization of the powders, an increase in the coercive field was observed for certain milling times. Micrometric powders sourced from the wind turbine, milled for 10 min using 5 mm balls, exhibited the highest coercive field of 0.27 T. This behavior is discussed considering the effect of the particle size reduction, the structural damage, the particle agglomeration, and the local compositional changes. We conclude that the powders produced from different source magnets exhibit similar patterns of morphological, structural, and magnetic changes under milling, and only the Tc and the Hc of the powders depend on their original magnet. Ball milling represents a promising technique for particle size refining in the hydrogen processing of magnetic scraps, a crucial step in the magnet-to-magnet recycling process. Full article

This study examines interfacial intermetallic compound (IMC) growth in Pb-free/Pb mixed assemblies comprising 450 µm SAC305 solder balls and Cu pads printed with a 0.12 mm layer of Sn63Pb37 solder paste. Samples were reflowed at peak temperatures of 200, 220, 240, and 260 °C, with the time above 217 °C fixed at 40 s. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and electron backscatter diffraction were used to characterize the interfacial composition, morphology, layer thickness, grain size, and kernel average misorientation (KAM). The IMC layer thickened from 1.5 µm at 200 °C to 6.0 µm at 260 °C, while KAM_ave increased from 0.36° to 0.59°. At 220 °C, the IMC thickness changed only slightly to 1.6 µm, accompanied by local Pb and Ag enrichment. At 240 °C, the IMC thickness increased sharply to 4.7 µm and KAM_ave increased to 0.55°, together with larger Cu₆Sn₅ grains and localized coarsening. At 260 °C, the IMC thickness reached 6.0 µm and KAM_ave reached 0.59°, while Pb-rich regions became more pronounced and the Ag content decreased markedly, indicating substantial interfacial solute redistribution and increasingly heterogeneous IMC growth. The results link the reflow temperature to changes in interfacial chemistry, and microstructure and can help define a suitable process window for Pb-free/Pb mixed assembly. Full article

Ceramic balls are utilized as grinding media for regrinding of titanomagnetite rougher, owing to its low liberation degree and intricate intergrowth with gangue minerals. Process mineralogy, regrinding experiments and EDEM simulations were adopted to investigate the influencing mechanism of ceramic balls on the regrinding performance of titanomagnetite rougher. The Dv(90) of titanomagnetite rougher is 198.19 μm, and the titanomagnetite is closely intergrown with gangue minerals, including chlorite, serpentine and ilmenite, in the forms of inclusions, interlocks and solid solutions with a liberation degree of 75.54%. The Dv(90) reduces to 39.86 μm, and the liberation degree of titanomagnetite increases to 92.86% after regrinding with ceramic balls. The grade was improved from 53.01% to 58.83% with a recovery of 96.19% after magnetic separation. EDEM simulation results reveal that raising stirrer speed elevated collision energy, increasing pulp density enhanced viscous coupling and particle capture, and improving media filling ratio boosted collision frequency. These findings demonstrate that ceramic balls could effectively refine product size, facilitate mineral liberation and improve concentrate grade, offering a viable pathway toward efficient utilization of titanomagnetite. Full article

Let $K\subset {\mathbb{R}}^n$ be a bounded convex body. We prove a lattice-averaging formula that gives upper bounds for the number of unit balls required to cover K. If the Voronoi cell P of a lattice is contained in the Euclidean unit ball, then some translate and rotation of the lattice produces a covering whose size is at most a linear combination of the intrinsic volumes of K; the coefficients are determined by the intrinsic volumes of P. The proof averages the number of Voronoi cells meeting K over one fundamental cell and over $SO\left(n\right)$. For the regular hexagonal lattice in ${\mathbb{R}}^2$, the formula reproduces the classical planar Blaschke bound. For the cubic lattice, it gives a closed-form estimate in every dimension $n\ge 2$. In ${\mathbb{R}}^3$, explicit computations for the cubic, face-centered cubic, and body-centered cubic Voronoi cells show that the body-centered cubic lattice has the smallest coefficientwise bound among these three lattices. In ${\mathbb{R}}^4$, the intrinsic volumes of the $A_4^{\ast }$ permutohedron are computed from its graphical-zonotope representation, leading to a sharper bound than for the cubic lattice. Full article

Reproductive performance and follicular dynamics in captive female ball pythons (Python regius) were investigated to evaluate reproductive efficiency, assess the usefulness of ultrasonography, and examine the relationship between follicular size and ovulation timing. Reproductive parameters included follicular development, ovulation rate, ovulation-to-oviposition interval, egg quality, and hatching success. Monthly ultrasonographic examinations were performed from March to August using a 7.5 MHz linear probe, and the findings were compared with manual palpation. Overall, 58.3% of females ovulated and laid eggs. Ovulation occurred mainly between April and August, whereas egg laying took place from June to November. The median clutch size was six eggs, and incubation lasted approximately 58 days. Ultrasonography effectively monitored follicular development, showing progressive changes in echogenicity and significant increases in follicular diameter throughout the breeding season. A strong negative correlation was found between follicular size and days to ovulation (r = −0.88; p < 0.001). Follicles measuring ≥20 mm showed a median growth rate of 0.38 mm/day. Manual palpation showed lower diagnostic accuracy, with a 25% false-negative rate. This study provides baseline reproductive data that may improve captive breeding management, animal welfare, and future reproductive research, including the development of reproductive biotechnologies in this species. Full article

Despite decades of surface science research, there is a lack of an universal approach to define the adsorption geometry in catalysis on metal nanoparticles and surfaces. The unified framework introduced in this work allows the comparison of binding sites across different facets and particle-size metals, including stepped surfaces, adatoms and surface vacancies. In this study, we identify 18 adsorption sites on metal nanoparticles and surfaces that have either a face-centred cubic (FCC) or hexagonal close-packed (HCP) structure. Most metals in the periodic table have these structures and we determined the adsorption site geometry on a nanoparticle using a geometric approach with physical magnetic ball-and-stick models. These geometric models include the existence of an octahedral or tetrahedral hole beneath the adsorption site, as these can affect the adsorption site strengths of adsorbates. Furthermore, these adsorption sites are a combination of three-fold hollows and four-fold hollows, which are adsorption sites known to activate diatomic molecules (e.g., N₂ and CO). In addition, adsorption of large-molecular-weight adsorbates can be defined on these sites as they provide multiple contact points in contrast to the typical four-fold hollow, three-fold hollow, and bridge and atop adsorption sites used in heterogeneous catalysis. We find that there are nine geometrically distinct adsorption site topologies composed of square (i.e., 100) and triangular (i.e., 111) motifs. These adsorption site topologies, when combined with a characteristic zeta angle (ζ), result in 18 distinct adsorption site geometries that can be found on metal nanoparticles and surfaces. A systematic naming system for these adsorption sites is provided that defines the adsorption site geometry explicitly. Using this approach, we find that there are five different types of B5 sites, an adsorption site that has been previously found to activate dinitrogen on ruthenium for the ammonia synthesis reaction. Full article

Comminution–classification circuits are difficult to optimize because hydraulic, granulometric, energy, and economic responses are nonlinearly coupled, while circuit simulation, equipment sizing, simulator benchmarking, and operating optimization are often treated separately. This study aimed to develop an open Python framework for steady-state simulation and five-objective optimization of a rod mill–hydrocyclone–ball mill circuit processing a gold ore. The framework integrates solid and water balances, Rosin–Rammler particle-size reconstruction, comminution and hydrocyclone models, preliminary equipment sizing, explicit feasibility constraints, and Multiobjective Particle Swarm Optimization (MOPSO). Its novelty lies in coupling complete-circuit simulation, simulator-to-simulator benchmarking against USIM PAC^®, model-based sizing, convergence diagnostics, and Pareto optimization within one transparent workflow. The benchmark produced zero or below ${10}^{-3}\%$ errors in solid balances and sizing differences of 1.07%, 8.21%, and 0.00% for the rod mill, ball mill, and hydrocyclone, respectively. Relative to the base case, the joint minimum-water, minimum-energy, and minimum-cost solution reduced specific water consumption by 24.50%, specific grinding energy by 4.24%, specific operating cost by 10.19%, and mass recirculation by 8.80%, while useful recovery decreased slightly from 82.67% to 81.78%. The maximum-recovery solution increased useful recovery to 84.45%, with higher water, energy, and operating-cost requirements. The framework supports reproducible evaluation of resource–recovery trade-offs in grinding–classification circuits. Full article

Background/Objectives: The longevity of tooth-supported overdentures depends on the retentive stability of attachment systems, yet limited evidence exists on the performance of non-metallic CAD-CAM fabricated mini ball attachments. This study aimed to evaluate the retentive force changes and surface wear of CAD-CAM fabricated mini ball attachments made of zirconia, polyetheretherketone (PEEK), and polymethyl methacrylate (PMMA) for tooth-supported overdentures. Methods: Twenty-one mandibular canine replicas received CAD-CAM copings with mini ball attachments (n = 7 per material). Retentive force was measured at baseline and after 90, 270, 540, 1080 and 2160 insertion–removal cycles (simulating 2 years of clinical use). Surface wear was examined under scanning electron microscopy (one specimen per group, preliminary). Data were analyzed using one-way ANOVA, paired t-tests with Bonferroni correction, and mixed repeated-measures ANOVA (Greenhouse–Geisser correction). Effect sizes (partial η², Cohen’s d) were calculated. Based on a priori power analysis 7 specimens per group were decided. Results: All materials showed a significant decline in retention over cycles (p < 0.001, partial η² = 0.90). No significant differences were found among the three materials at any time point (p > 0.05). The material × time interaction was not significant (p = 0.064). Within each material, baseline-to-final reductions were significant (p ≤ 0.009, Cohen’s d > 3.0). Exploratory SEM suggested minimal wear for zirconia, moderate for PEEK, and pronounced surface deterioration for PMMA. Conclusions: Within the limitations of this study, all three CAD-CAM mini ball attachments provided decreasing but measurable retention over simulated use. Zirconia showed numerically the highest final retention, but no statistically significant differences were detected among materials. Clinically, zirconia attachments demonstrated numerically superior final retention with minimal wear, suggesting potential advantages for long-term use; however, the lack of statistically significant differences among materials and the preliminary nature of the wear analysis warrant caution, emphasizing the need for future clinical validation before definitive material recommendations can be made. Full article

Reintroducing crop straw into soil boosts organic matter, but natural crop straw usually shows low nutrient content. To enhance the water absorption rate of a certain thin sheet-shaped iron-containing material, a technical approach combining ball milling, the Mannich reaction, Schiff’s base cross-linking, emulsion separation, and solid–liquid adsorption was attempted to prepare iron-containing microspheres using sodium alginate and rice straw as raw materials. This approach increased the content of the trace nutrient iron and improved the water absorption rate. The results indicated that the iron-containing microspheres exhibit a diameter ranging from approximately 15 μm, an iron content of 10.44%, and a water absorption rate of 501.76%. The release rates of iron and nitrogen in soil and water within the first day were all below 15%, while the release rates after 30 days in soil were 61.8% for iron and 44.32% for nitrogen, and the corresponding rates in water were 73.1% for iron and 63.88% for nitrogen. The water absorption capacity of the iron-containing microspheres showed a trend associated with particle size and pore structure parameters. The development of iron-containing microspheres has expanded the preparation technology for semi-interpenetrating structure type sustained-release materials, and holds the potential for further development into slow-release fertilizers. Full article

Background and Objectives: Evidence on the acute effects of caffeine in female team-sport athletes is limited. This study aimed to quantify the acute effects of caffeine on female team-sport athletes across physical performance, sport-specific performance, physiological responses, perceptual responses, and cognitive performance and determine moderators. Methods: PubMed and Web of Science were systematically searched for randomized, placebo-controlled crossover trials of acute, dose-defined caffeine in female team-sport athletes. Effect sizes were expressed as Hedges’ g and synthesized within each domain using a three-level CHE model with CR2 cluster-robust variance estimation and Satterthwaite degrees of freedom; 95% confidence intervals and prediction intervals were reported. Risk of bias (RoB 2), methodological quality (PEDro), and certainty of evidence (GRADE) were assessed. Results: Twenty-six studies were included, comprising 26 randomized, blind, placebo-controlled crossover trials. As a descriptive cross-domain summary, acute caffeine intake showed a small overall effect when all available domains were pooled (Hedges’ g = 0.24, 95% CI 0.13 to 0.35); however, because these domains represent different constructs, domain-specific estimates were considered the primary interpretable findings. For physical performance, caffeine showed a small favorable effect (g = 0.32, 95% CI 0.22 to 0.42), with statistical evidence for repeated sprint ability (g = 0.43), agility or change in direction (g = 0.42), sprint or speed performance (g = 0.39), anaerobic power (g = 0.30), and jumping performance (g = 0.29). For sport-specific performance, the pooled estimate indicated a small favorable effect but did not reach conventional statistical significance (g = 0.36, 95% CI: −0.01 to 0.73). Exploratory sub-indicator analyses, each based on only a few studies, suggested possible favorable directions for sport-specific locomotion or running performance (g = 0.46) and throwing or ball-speed outcomes (g = 0.19), whereas evidence was insufficient for shooting or scoring accuracy. Physiological outcomes were direction-aligned to the value conventionally regarded as favourable for each indicator (i.e., lower heart rate, lactate, and glucose), so that positive values denote the conventionally favourable direction; because the domain aggregates indicators of differing clinical desirability, its pooled value is a descriptive summary only and showed no clear domain-level direction (g = −0.05, 95% CI −0.31 to 0.21). The heart rate submetric showed a statistically detectable difference (g = −0.30), indicating that caffeine increased heart rate, the expected pharmacological response to a stimulant rather than an adverse effect; there were no clear effects on blood lactate or blood glucose. Perceptual responses improved modestly (g = 0.42), largely through reduced rating of perceived exertion (g = 0.35). Cognitive performance, based on only four studies with low degrees of freedom and wide uncertainty, showed a nonsignificant direction (g = 0.37) with no clear evidence for reaction time or cognitive accuracy, and these data should not be interpreted as showing that caffeine improves cognitive performance in female team-sport athletes. Exploratory moderator analyses did not provide statistically reliable evidence of moderation by caffeine dose, timing of intake, formulation or source, sport type, competitive level, habitual caffeine intake, or blinding status. Conclusions: Available evidence most consistently supports small, outcome-specific benefits of acute caffeine for physical performance and reduced perceived exertion. Evidence for sport-specific skills and cognitive outcomes remained uncertain, based on few studies per outcome and not supporting a general benefit. Current data do not support dose-, timing-, formulation-, habitual-intake-, sport-, or population-stratified recommendations. Future trials should be adequately powered, prospectively report menstrual-cycle phase, hormonal-contraceptive use, habitual caffeine intake, and adverse symptoms, and verify the integrity of blinding. Full article

Stable drainage of coalbed methane wells is essential for reducing reservoir pressure and promoting methane desorption. However, coal fines carried by produced water tend to accumulate and deposit within the standing valves of drainage pumps. To address this common problem, this study investigates the transport characteristics of coal fines within the standing valve during the liquid-dominated water-pumping stage of the plunger upstroke, with the standing valve fully open. Theoretical calculations, numerical simulations, and settling experiments were conducted for three coal fines size fractions of 60–100, 100–200, and 200–400 mesh to validate the model’s predictive capability for coal fines motion. The results show that the RNG k–ε model has the lowest mean absolute relative error, at 14.50%. A solid–liquid two-phase flow model was employed to comparatively analyze five valve seat cone angles ranging from 105° to 165° and representative inlet velocities of 0.1–0.4 m/s. The results indicate that the mixture within the standing valve accelerates markedly while passing through the narrow clearance between the valve ball and the valve seat and then decelerates in the region above the valve ball. The region above the valve ball and the valve seat transition region are the primary locations of instantaneous coal fines enrichment. Increasing the inlet velocity generally enhances coal fines transport capacity and reduces the local maximum solid-phase volume fraction. Larger coal fines particles exhibit more pronounced inertial deviation and a higher degree of local enrichment, whereas smaller particles show stronger flow-following behavior and a more dispersed spatial distribution. The results further indicate that, within the investigated structural range, the 150° valve seat cone angle provides the best overall balance between coal fines transport capacity and hydraulic resistance. Ultimately, the findings provide a theoretical foundation and methodological reference for understanding the anti-clogging mechanisms of CBM pump standing valves, optimizing structural parameters, and guiding the blockage-resistant design of downhole flow components. Full article

High-temperature and high-salinity reservoirs (typically referring here to temperatures ≥ 100 °C and salinities > 100 g/L) impose stringent requirements on chemical flooding and profile-control agents, particularly in terms of thermal stability, salt tolerance, injectivity, and environmental compatibility. In this study, a bio-based composite mobility-control and oil-displacement system was developed by combining carbonized corn-straw particles with the biopolymer scleroglucan. Corn-straw biomass particles were prepared by pyrolysis at 500 °C followed by ball milling for 2 h. Their particle-size distribution, elemental composition, and suspension stability were characterized, and the rheological behavior, thermal and salt tolerance, long-term aging stability, injectivity, plugging performance, and enhanced-oil-recovery efficiency of the composite system were evaluated systematically. The average particle size decreased from 25.6 μm for mechanically ground straw to 2.8 μm after carbonization and ball milling. The H/C atomic ratio of the carbonized particles was 0.31, indicating enhanced aromatization and structural stability. A scleroglucan concentration of 1000 ppm provided a suspension rate of 97%, balancing suspension stability and chemical dosage. The composite system maintained stable viscosity and viscoelasticity from 30 to 130 °C in deionized water, saturated NaCl solution, and saturated CaCl₂ solution, with viscosity loss below 10%. After sealed anaerobic aging at 100 °C for 28 days, the viscosity retention remained above 90%. Sand-pack tests showed stable injectivity in media with permeabilities of 1235 and 2064 mD and a plugging efficiency of 95.7% in a 2846 mD model. In oil-displacement experiments, the composite system increased the final recovery factor from 46.6% for scleroglucan flooding alone to 53.3%, corresponding to an additional 6.7 percentage points. These results demonstrate that the carbonized biomass particle-scleroglucan system has promising thermal stability, salt tolerance, plugging capacity, and oil-displacement performance, providing a potential green strategy for mobility control in harsh reservoir environments. Full article

Spent water-based drilling fluids generated during the construction of technological wells impose substantial environmental, water-management, transportation, and energy burdens. Conventional practices, including storage in temporary pits, prolonged settling, and off-site disposal, do not enable process-water recovery and require repeated handling of suspensions with a high solids content. This study evaluates a pressure-driven cylindrical hydrodynamic disperser as the central component of a compact on-site treatment system. Unlike conventional mechanical mixers, the disperser contains no driven shaft within the active chamber. Particle–reagent contact is intensified through controlled jet shear, vortex-induced redistribution, and the motion of freely moving steel balls. Field-derived drilling fluids containing 30–40 wt.% solids, with densities of 1.12–1.17 g/cm³, pH values of 7.4–8.2, and median particle sizes of 15–50 μm, were treated at velocity gradients of 500–1500 s⁻¹ for 60–180 s using Superfloc N-300 dosages of 0–100 g/t. The optimal operating conditions were G = 1300 s⁻¹, τ = 150 s, and D = 50 g/t. Under these conditions, the separation efficiency reached 91–93%, the residual suspended-solids concentration decreased to 120–130 mg/L, process-water recovery reached 80%, sludge volume decreased by 40–60%, and specific energy consumption was approximately 0.30 kWh/m³. More intensive treatment increased the separation efficiency to 94–95% but resulted in a less favorable balance among energy consumption, reagent dosage, and resource recovery. Compared with mechanical mixing, the selected treatment system reduced flocculant consumption by 37.5%, treatment time by more than threefold, and specific energy consumption by 40%. These results support the use of modular on-site systems for process-water recirculation and reduced sludge-transport requirements at remote drilling sites. Full article

This study investigates the synthesis of La_0.6Ca_0.4FeO₃ (LCF) perovskite via a ball milling method for application in reverse water–gas shift chemical looping (RWGS-CL) for CO₂-to-CO conversion. Unlike conventional wet-chemical routes such as the Pechini method, the ball milling approach offers a solvent-free, scalable synthesis using low-cost metal oxide precursors (e.g., La₂O₃, CaO, Fe₂O₃). Structural analysis by XRD confirmed the successful formation of single-phase cubic perovskite, with no secondary phases when using oxide precursors. Crystallite size increased with calcination temperature, from 118.9 Å (no calcination) to 404.3 Å (1050 °C). BET analysis revealed a decrease in surface area from 2.5 m²/g (no calcination) to 0.51 m²/g (1050 °C), consistent with sintering at higher temperatures. TPR-H₂ and TPO-CO₂ studies revealed that non-calcined LCF possesses slightly enhanced redox properties, with oxygen vacancy formation and CO₂ reoxidation activity both at 500 °C. RWGS-CL experiments demonstrate that all LCF samples exhibit stable CO production (910–970 µmol/g_LCF) over multiple cycles at 500 °C, with comparable performance across calcination conditions. A cost and sensitivity analysis reveals that the ball milling method had lower synthesis costs by approximately 92% at the laboratory-scale and 88% at the industrial-scale compared to the Pechini method, highlighting its strong potential for large-scale perovskite production. Full article