Search Results (231)

Filled-polymer coatings enable functional surfaces for selective metallisation, wetting control and local conductivity, but pulsed-laser texturing is often limited by process non-uniformity caused by scan kinematics and plume shielding. Here, we develop a three-tier numerical workflow for nanosecond pulsed-laser surface treatment of a thermoplastic coating containing glass microspheres (baseline case: PLA matrix with V_f = 0.20; spheres represented via an effective optical transport model). Tier 1 predicts spatially resolved ablation depth under raster scanning, using an incubation law and regime switching (no-removal/melt-limited/logarithmic ablation/blow-off) coupled to a dynamic shielding factor. Tier 2 computes the 1D transient (pulse-averaged) temperature field and the thickness of the thermally softened layer. Tier 3 models post-pulse capillary redistribution of the softened layer to estimate groove reshaping. The simulations show that scan overlap and shielding dynamics dominate groove homogeneity more strongly than average power alone: under identical average power, variations in local pulse count and shielding lead to significant changes in depth statistics and regime fractions. The workflow produces quantitative maps and summary metrics (mean depth, P5–P95 range, uniformity index and regime fractions) and demonstrates how controlled reflow can smooth peaks while preserving groove depth. These results provide a predictive tool for laser parameter selection and process optimisation prior to experimental trials. Full article

Based upon density functional theory (DFT) calculations, we present the basic electronic structure of CuPb₉(PO₄)₆O (Cu-doped lead apatite, aka LK-99), in two scenarios: (1) where the structure is constrained to the P3 symmetry and (2) where no symmetry is imposed. At the DFT level, the former is predicted to be metallic while the latter is found to be a charge-transfer insulator. In both cases the filling of these states is nominally $d^9$, consistent with the standard Cu²⁺ valence state, and Cu with a local magnetic moment of order 0.7 μ_B. In the metallic case we find these states to be unusually flat (∼0.2 eV dispersion), giving a very high density of electronic states (DOS) at the Fermi level that we argue can be a host for novel electronic physics. The flatness of the bands is the likely origin of symmetry-lowering gapping possibilities that would remove the spectral weight from $E_F$. Motivated by some initial experimental observations of metallic or semiconducting behavior, we propose that disorder (likely structural) is responsible for closing the gap. Here, we consider a variety of possibilities that could possibly close the charge-transfer gap but limit consideration to kinds of disorder that preserve electron count. Of the possible kinds we considered (spin disorder, O populating vacancy sites, and Cu on less energetically favorable Pb sites), the local Cu moment, and consequently the charge-transfer gap, remains robust. We conclude that disorder responsible for metallic behavior entails some kind of doping where the electron count changes. Further, we claim that the emergence of the flat bands should be due to weak wave function overlap between the orbitals on Cu and O sites, owing to the directional character of the constituent orbitals. Therefore, finding an appropriate host structure for minimizing hybridization between Cu and O while allowing them to still weakly interact should be a promising route for generating flat bands at $E_F$ which can lead to interesting electronic phenomena, regardless of whether LK-99 is a superconductor. Full article

The 2025 International Technology Roadmap for Photovoltaics (ITRPV) projects that bifacial modules will dominate the photovoltaic (PV) market, reaching roughly 60–80% global share between 2024 and 2035, while monofacial PV modules will steadily decline. Current industry practice is to route the cable bundles along structural members such as main beams or torque tubes, thereby preventing rear-side shading but resulting in two key drawbacks: increased cable length and decreased system reliability due to cable proximity with rotating members and pinch points. Both effects contribute to higher system costs and reduced cable reliability. An alternative method involves suspending cable bundles directly behind the modules using hangers. While this approach mitigates excess length and risk of cable snags, it introduces the possibility of partial rear-side shading, which could possibly cause performance loss and hot-spot formation due to shade-induced electrical mismatch. Experimental evidence indicates that this risk is minimal, as albedo irradiance typically represents only 10–30% of front-side irradiance as reported in the literature and is largely diffuse, thereby limiting the likelihood of significant directional shading. This study evaluates the performance and reliability impacts of hanger-supported cable bundles under varying experimental conditions. Performance metrics assessed include maximum power output (Pmax), short-circuit current (Isc), open-circuit voltage (Voc), and fill factor (FF), while hot-spot risk was evaluated through measurements of module temperature uniformity using infrared imaging. Each cable (1X) was 6 AWG with a total outer diameter of approximately 9 mm. Experiments covered different cable bundle counts/sizes (2X, 6X, 16X), mounting configurations (fixed-tilt and single-axis tracker), and albedo conditions (snow-covered and snow-free ground). Measurements were conducted hourly on clear days between 8:00 and 16:00 from June to September 2025. The results consistently show that hanger-supported cable bundles have a negligible shading impact across all hours of the day and throughout the measurement period. This indicates that rear-side cable shading can be safely and practically disregarded in performance modeling and energy-yield assessments for the tested configurations, including fixed-tilt systems and single-axis trackers with or without torque tube shading and with various hanger sizes and cable-bundle counts. Therefore, hanging cables behind modules is a cost- and reliability-friendly, safe and recommended practice. Full article

This study investigates the aerodynamic characteristics of drafting cyclists during 45° cornering through numerical simulations, and under the conditions of a vehicle speed of 15 m/s and a 45° body inclination, the SST k-ω turbulence model and grid independence verification (final grid count:12 million) are used to systematically analyze the distribution of velocity, vortex, pressure, and wall shear stress fields. The effects of riding velocity (5–25 m/s) and inter-rider spacing (100–500 mm) on aerodynamic drag were analyzed to reveal the underlying flow mechanisms. The results indicate that as velocity increases, airflow acceleration and boundary-layer shear intensify, leading to enhanced vortex shedding and elevated wall shear stress. In contrast, reduced spacing significantly strengthens wake coupling between riders, effectively lowering the frontal pressure and skin-friction drag of trailing cyclists. The drag reduction rate decreases monotonically with increasing spacing, with the second rider consistently achieving higher aerodynamic benefits than the third rider. Distinct from previous studies that predominantly focus on straight-line motion, this work fills a critical knowledge gap in sports aerodynamics and competitive cycling strategy. By elucidating the unique wake coupling mechanisms induced by body inclination, this study provides scientific evidence for optimizing drafting tactics specifically during high-speed technical cornering. Full article

Vision Transformers achieve strong performance across computer vision tasks but suffer from quadratic computational complexity with respect to token count, limiting deployment in resource-constrained environments. Existing token pruning methods rely on attention scores to identify important tokens, but attention mechanisms capture query-specific relevance rather than intrinsic information content, potentially discarding tokens that carry information for subsequent layers or different downstream tasks. We propose fractal-guided token pruning, a method that leverages the correlation dimension $D_{\mathrm{corr}}$ of token embeddings as a task-agnostic measure of geometric complexity. Our key insight is that tokens with high $D_{\mathrm{corr}}$ span higher-dimensional manifolds in representation space, indicating complex patterns, while tokens with low $D_{\mathrm{corr}}$ collapse to simpler structures representing redundant information. By computing a local $D_{\mathrm{corr}}$ for each token and pruning those with the lowest values, our method retains geometrically complex tokens independent of attention-based relevance. The correlation dimension quantifies how token embeddings fill the representation space: embeddings from uniform background regions cluster tightly in low-dimensional subspaces (low $D_{\mathrm{corr}}$), while embeddings from complex textures or object boundaries spread across higher-dimensional manifolds (high $D_{\mathrm{corr}}$), reflecting their richer information content. Experiments on CIFAR-10 and CIFAR-100 with fine-tuned ViT-B/16 models show that fractal-guided pruning consistently outperforms random and norm-based pruning across all tested ratios. At forty percent pruning, fractal pruning maintains 92.26% accuracy on CIFAR-10 with only a 0.99 percentage point drop from the 93.25% baseline while achieving 1.17× speedup. Our approach provides a geometry-based criterion for token importance that complements attention-based methods and shows promising generalization between CIFAR-10 and CIFAR-100 datasets. Full article

Engineering unloading activities during deep mineral resource extraction subject the backfill materials to complex true triaxial stress conditions, where their mechanical behavior and damage mechanisms are critical to stope stability. In this article, a true triaxial testing system was employed to conduct unloading tests under different initial intermediate principal stress (σ₂) conditions, aiming to elucidate the influence mechanism of σ₂ on strength, deformation, failure modes, and acoustic emission (AE) characteristics of the backfill, and to establish a corresponding damage constitutive model. The results demonstrate that the σ₂ governs the mechanical response and failure mode of the filling material. Within the tested range, σ₂ nonlinearly enhances both the peak stress, indicating improved load-bearing. As σ₂ increases, acoustic emission activity changes from intermittent to continuous high-intensity ringing counts. The transition from brittle to ductile fracture. Model predictions showed high agreement with experimental data, validating its applicability. This study provides a critical theoretical foundation and modeling framework for assessing the stability of backfill structures under deep well mining conditions and guiding engineering design. Full article

Filling mining offers significant technical advantages in controlling rock mass movement and preventing disasters. Investigating the correlation between the macro- and micro-scale characteristics of filling materials will help optimize this process. The paper analyzes the variation patterns and mechanisms of the pore structure and mechanical strength characteristics of the filling body based on low-field nuclear magnetic resonance (NMR) technology and fractal theory, exploring the relationship between microstructure and macroscopic features. Results indicate that as the cement-to-sand ratio or mass concentration decreases, the total pore structure count in the filling material increases, predominantly consisting of micropores that account for over 76%. The complexity of total pores, micropores, mesopores, and macropores progressively decreases. Mechanical strength exhibits a positive correlation with both the cement-to-sand ratio and mass concentration. A reduced cement-to-sand ratio diminishes hydration products, lowering the cohesive strength of tailings particles. As mass concentration increases, the internal structure of the filling body becomes denser, enhancing its mechanical properties. An increase in pore number progressively improves pore connectivity, reducing fluid flow resistance. The porosity of the pore structure exhibits a strong correlation with fractal dimension, mechanical strength, and permeability coefficient, with a coefficient of determination ranging from 0.631 to 0.996. The strength prediction model constructed using mesopore porosity and material intrinsic characteristics also demonstrated excellent accuracy. Full article

Advances in sensor technology have significantly improved the efficiency and precision of agricultural spraying. Unmanned aerial vehicles (UAVs) are widely utilized for applying plant protection products (PPPs) and fertilizers, offering enhanced spatial control and operational flexibility. This study evaluated the performance of an autonomous UAV-based precision spraying system that applies variable rates based on zone levels defined in a prescription map. The system integrates real-time kinematic global navigation satellite system positioning with a proximity-triggered spray algorithm. Field experiments on a rice field were conducted to assess spray accuracy and fertilization efficacy with liquid fertilizer. Spray deposition patterns on water-sensitive paper showed that the graded strategy distinguished among zone levels, with the highest deposition in high-spray zones, moderate in medium zones, and minimal in no-spray zones. However, entry and exit deviations—used to measure system response delays—averaged 0.878 m and 0.955 m, respectively, indicating slight lags in spray activation and deactivation. Fertilization results showed that higher application levels significantly increased the grain-filling rate and thousand-grain weight (both p < 0.001), but had no significant effect on panicle number or grain count per panicle (p > 0.05). This suggests that increased fertilization primarily enhances grain development rather than overall plant structure. Overall, the system shows strong potential to optimize inputs and yields, though UAV path tracking errors and system response delays require further refinement to enhance spray uniformity and accuracy under real-world applications. Full article

Fresh mulberry juice (MJ) faces industrial challenges due to its short shelf life and inconsistent flavor. This study innovatively addressed these limitations by applying L. plantarum (LP) and L. fermentum (LF) fermentation to MJ, combining non-targeted metabolomics and GC-IMS to systematically elucidate metabolic remodeling and flavor enhancement. Fermentation (36 h) achieved LAB counts > 7 log CFU/mL, significantly reducing soluble solids and pH from 15.00 to 13.90, 14.01 °Brix and 3.74 to 3.21, 3.13, respectively. In contrast, the bioactive compounds as detected by the increase in flavonoids and phenolics from 254.85 mg/100 g to 289.36, 291.39 mg/100 g and 286.21 mg/100 g to 294.55, 302.2033 mg/100 g, respectively. Anthocyanin content as high as 165.88 and 156.69 mg/L. Metabolomics identified enriched amino acid pathways, and GC-IMS revealed unique flavor profiles. The study fills a research gap by demonstrating LAB fermentation’s dual role in extending MJ’s shelf life and improving its functional nutritional quality, offering a novel strategy for functional food development. Full article

Background: Urinary continence relies on a complex interplay between urine storage and voiding involving both spinal reflex circuits and supraspinal brain areas to coordinate volun-tary control over emptying. Despite a vast number of studies on the pathophysiology of neurogenic bladder and urge incontinence, less is known about the central correlates of bladder filling. Methods: An ALE (activation likelihood estimation) meta-analysis including a total count of 14 studies investigating 243 participants under different conditions of bladder filling during functional neuroimaging was performed to demonstrate the neuroanatomical correlates of bladder filling. The literature search and reporting were conducted according to the PRISMA-P 2020 guideline. Data analysis was performed using the GingerAle software version 3.0.2 and was displayed with the Mango software 4.1 on an anatomical MNI template. Results: Synthesizing studies on the functional neuroanatomy of urine storage, bihemispheric clusters of activation in the thalamus, the insula and the cingulate were observed. Conclusion: The present ALE meta-analysis indicates that the supraspinal representation of urine storage involves areas of autonomous–homeostatic processing which allow for the perception of the usually unconscious inner state of bladder filling and enable postponing and voluntary voiding. Full article

Background/Objectives: The ongoing prevalence of dental issues within the school-age population continues to present significant public health challenges. This study aims to thoroughly evaluate the oral health conditions of schoolchildren aged 7–10 years, with a particular focus on identifying the prevalence and severity of dental caries, as well as their relationship with dental hygiene and dietary habits. Methods: A cross-sectional approach was employed involving 700 children aged from 7 to 10 years, recruited from nine urban and rural educational institutions across two Romanian counties, namely Mureș and Bistrița-Năsăud. Data were collected regarding the sociodemographic characteristics of participants, including parental educational background and occupational status. Furthermore, information on dental hygiene routines was gathered, encompassing tooth brushing habits, flossing usage, frequency of brushing, along with dietary details such as daily meal count, snacking frequency, and sugar intake levels. An oral examination was performed by a trained specialist to assess the condition of the children’s teeth, documenting the number of decayed, missing, and filled teeth. The presence of plaque was evaluated using a plaque index, and the dental caries status was quantified using the Decayed, Missing, and Filled Teeth (DMFT) index. Results: The findings revealed that the average plaque score was marginally higher in boys (mean = 0.69 ± 0.36) compared to girls (mean = 0.65 ± 0.40). Additionally, children from urban environments demonstrated a mean plaque score of 0.61 ± 0.32, whereas their rural counterparts exhibited a higher score of 0.73 ± 0.38. In multivariable models, irregular brushing, higher daily sugar consumption, and ≥3 snacks/day were independently associated with both caries prevalence (DMFT > 0) and greater DMFT counts (p < 0.05). Conclusions: The evidence denotes a concerning association between poor oral hygiene practices and higher rates of tooth decay among children, particularly among those with elevated sugar intake and frequent snacking behaviors. Dental public health professionals are encouraged to incorporate considerations of oral hygiene habits when developing future health promotion strategies aimed at improving the oral health status of children. Full article

With global sustainable construction growth, fully recycled coarse aggregate concrete (RCAC)—eco-friendly for cutting construction waste and reducing natural aggregate over-exploitation—has poor durability in seasonally freezing saline-soil regions (e.g., Tumushuke, Xinjiang): freeze-thaw and salt ions (NaCl, Na₂SO₄) cause microcracking, faster performance decline, and shorter service life, limiting its use and requiring better salt freeze resistance. To address this, a field survey of Tumushuke’s saline soil was first conducted to determine local salt type and concentration, based on which a matching 12% NaCl + 4% Na₂SO₄ mixed salt solution was prepared. RCAC specimens modified with fly ash (FA), silica fume (SF), and polypropylene fiber (PPF) were then fabricated, cured under standard conditions (20 ± 2 °C, ≥95% relative humidity), and subjected to rapid freeze-thaw cycling in the salt solution. Multiple macro-performance and microstructural indicators (appearance, mass loss, relative dynamic elastic modulus (RDEM), porosity, microcracks, and corrosion products) were measured post-cycling. Results showed the mixed salt solution significantly exacerbated RCAC’s freeze-thaw damage, with degradation severity linked to cycle count and admixture dosage. The RCAC modified with 20% FA and 0.9% PPF exhibited optimal salt freeze resistance: after 125 cycles, its RDEM retention reached 75.98% (6.60% higher than the control), mass loss was only 0.28% (67.80% lower than the control), and its durability threshold (RDEM > 60%) extended to 200 cycles. Mechanistic analysis revealed two synergistic effects for improved performance: (1) FA optimized pore structure by filling capillaries, reducing space for pore water freezing and salt penetration; (2) PPF enhanced crack resistance by bridging microcracks, suppressing crack initiation/propagation from freeze-thaw expansion and salt crystallization. A “pore optimization–ion blocking–fiber crack resistance” triple synergistic protection model was proposed, which clarifies admixture-modified RCAC’s salt freeze damage mechanism and provides theoretical/technical guidance for its application in extreme seasonally freezing saline-soil environments. Full article

Background. Length of stay, operationalized here as nights per booking (NPB), is a first-order driver of yield, labor planning, and environmental pressure. The COVID-19 pandemic and the rise of long-stay remote workers (often labeled “slomads”, a slow-travel subset of digital nomads) plausibly altered stay-length distributions, yet national, booking-weighted evidence for the United States remains scarce. Purpose. This study quantifies COVID-19 pandemic-era and post-pandemic shifts in U.S. Airbnb stay lengths, and identifies whether higher averages reflect (i) more long stays or (ii) longer long stays. Methods. Using every U.S. Airbnb reservation created between 1 January 2019 and 31 December 2024 (collapsed to booking-count weights), the analysis combines: weighted descriptive statistics; parametric density fitting (Gamma, log-normal, Poisson–lognormal); weighted negative-binomial regression with month effects; a two-part (logit + NB) model for ≥28-night stays; and a monthly SARIMA$(0,1,1){(0,1,1)}_{12}$ with COVID-19 pandemic-phase indicators. Results. Mean NPB rose from 3.68 pre-COVID-19 to 4.36 during restrictions and then stabilized near 4.07 post-2021 (≈10% above 2019); the booking-weighted median shifted permanently from 2 to 3 nights. A two-parameter log-normal fits best by wide AIC/BIC margins, consistent with a heavy-tailed distribution. Negative-binomial estimates imply post-vaccine bookings are 6.5% shorter than restriction-era bookings, while pre-pandemic bookings are 16% shorter. In a two-part (threshold) model at 28 nights, the booking share of month-plus stays rose from 1.43% (pre) to 2.72% (restriction) and settled at 2.04% (post), whereas the conditional mean among long stays was in the mid-to-high 50 s (≈55–60 nights) and varied modestly across phases. Hence, a higher average NPB is driven primarily by a greater prevalence of month-plus bookings. A seasonal ARIMA model with pandemic-phase dummies improves fit over a dummy-free specification (likelihood-ratio = 8.39, df = 2, p = 0.015), indicating a structural level shift rather than higher-order dynamics. Contributions. The paper provides national-scale, booking-weighted evidence that U.S. short-term-rental stays became durably longer and more heavy-tailed after 2020, filling a gap in the tourism and revenue-management literature. Implications. Heavy-tailed pricing and inventory policies, and explicit regime indicators in forecasting, are recommended for practitioners; destination policy should reflect the larger month-plus segment. Full article

Objectives: Comparison of clinical, radiological, and microbiological outcomes following periodontal regeneration procedures with or without local antibiotic therapy. Methods: Forty patients, each presenting with a single vertical defect, were randomly assigned to either the test (SRP+ANB+MIST/M-MIST) or the control group (SRP+MIST/M-MIST). The periodontal regenerative procedures were carried out according to the general minimally invasive surgical technique principles, and the vertical bone defect was filled with an enamel matrix derivative (EMD—Emdogain^®). Periodontal condition assessments were performed two weeks before the procedure, on the day of the surgical procedure, and at follow-up visit after 6 months. Radiographs were taken two weeks before, and 6 months after the surgery. To determine the microbiological profile of the surgical sites, subgingival plaque samples were collected for PCR analysis. Results: In both groups, a statistically significant pocket depth (PD) reduction and clinical attachment level (CAL) gain were observed over the 6-month follow-up period. The difference between the groups for PD and CAL parameters at 6 months was not statistically significant. Both groups showed a statistically significant reduction in the radiological depth and width of intrabony defects. Microbiological analysis revealed a statistically significant difference between the groups two weeks after subgingival antibiotic application for Fusobacterium nucleatum, Tannerella forsythia, and Prevotella intermedia. Conclusions: Periodontal tissue regeneration procedures according to minimally invasive principles (MIST/M-MIST) with the use of EMD lead to improvements in clinical and radiological parameters. Local antibiotic application results in a reduction in bacterial counts in short-term observations. Its use prior to regeneration procedures does not lead to additional improvements in clinical and radiological parameters. Full article

Low plant stands at early crop establishment contribute to yield reduction in legumes. Gap-filling has been suggested as a mechanism to mitigate these losses. There is, however, limited understanding of a yield-compensation mechanism in the cowpea. This study aimed to investigate the mechanism of yield-compensation in some accessions of cowpeas at Minjibir and Shika in Northern Nigeria. The experiment was laid out in a split plot fitted into a randomized complete block design in three replicates. The main plot consisted of four plant densities (33,333; 66,666; 99,999; 133,333 plants ha⁻¹) while the subplots consisted of six cowpea accessions (IT89KD-288, IT93K-452-1, IT99K-537-1-1, IT98K-205-8, IT08K-150-27, and DANILA). Results showed that plant density and environment affected grain yield. Total grain yield increased with increasing plant density and was higher at Minjibir than at Shika. The highest total grain yield of 1793.3 kg ha⁻¹ was observed in the accession DANILA at 99,999 plants ha⁻¹, while the lowest (1100 kg ha⁻¹) was observed in the accession IT98K-205-8 at 33,333 plants ha⁻¹. Leaf area index, stand count at harvest, and intercepted photosynthetically active radiation were positively correlated with total grain yield at both locations, suggesting that these traits could be considered for cowpea improvement. Cowpea growers and breeders could consider the erect (IT93K-452-1 and IT98K-205-8) and semi-erect accessions (IT99K-573-1-1 and IT08K-150-27) for cultivation at 133,333 plants ha⁻¹. Prostrate accessions (IT89KD-288 and DANILA) could be planted at 99,999 plants ha⁻¹ at Minjibir. The accessions IT93K-452-1-1, IT98-205-8, IT99K-573-1-1, and IT08K-150-27 could be considered for cultivation at Shika irrespective of plant density. Full article