Search Results (67)

Although numerous observational and theoretical studies have examined the mean and turbulent structure of the tropical cyclone boundary layer (TCBL) over the open ocean, there have been comparatively fewer studies that have examined the kinematic and thermal structure of the TCBL across the land–ocean interface. This study examines the impact of different continental environments on the thermodynamic evolution of the TCBL during the landfall transition using high-resolution, full-physics numerical simulations. During landfall, the changes in the wind field within the TCBL due to the development of the internal boundary layer (IBL), combined with the formation of a surface cold pool, generates a pronounced thermal asymmetry in the boundary layer. As a result, the maximum thermodynamic boundary layer height occurs in the rear-right quadrant of the storm relative to its motion. In addition, azimuthal and vertical advection by the mean flow lead to enhanced turbulent kinetic energy (TKE) in front of the vortex (enhancing dissipative heating immediately onshore) and onshore precipitation to the left of the storm track (stabilizing the environment). The strength and depth of thermal asymmetry in the boundary layer depend on the contrast in temperature and moisture between the continental and storm environments. Dry air intrusion enhances cold pool formation and stabilizes the onshore boundary layer, reducing mechanical mixing and accelerating the decay of the vortex. The temperature contrast between the continental and storm environments establishes a coastal baroclinic zone, producing stronger baroclinicity and inflow on the left of the track and weaker baroclinicity on the right. The resulting gradient imbalance in the front-right quadrant triggers radial outflow through a gradient adjustment process that redistributes momentum and mass to restore dynamical balance. Therefore, the surface thermodynamic conditions over land play a critical role in shaping the evolution of the TCBL during landfall, with the strongest asymmetries in thermodynamic boundary layer height emerging when there are large thermal contrasts between the hurricane and the continental environment. Full article

Background/Objectives: Smart Formulation is an artificial intelligence-based platform designed to predict the Beyond Use Dates (BUDs) of compounded oral solid dosage forms. The study aims to develop a decision-support tool for pharmacists by integrating molecular, formulation, and environmental parameters to assist in optimizing the stability of extemporaneous preparations. Methods: A tree ensemble regression model was trained using a curated dataset of 55 experimental BUD values collected from the Stabilis database. Each formulation was encoded with molecular descriptors, excipient composition, packaging type, and storage conditions. The model was implemented using the KNIME platform, allowing the integration of cheminformatics and machine learning workflows. After training, the model was used to predict BUDs for 3166 APIs under various formulation and storage scenarios. Results: The analysis revealed a significant impact of excipient type, number, and environmental conditions on API stability. APIs with lower LogP values generally exhibited greater stability, particularly when formulated with a single excipient. Excipients such as cellulose, silica, sucrose, and mannitol were associated with improved stability, whereas HPMC and lactose contributed to faster degradation. The use of two excipients instead of one frequently resulted in reduced BUDs, possibly due to moisture redistribution or phase separation effects. Conclusions: Smart Formulation represents a valuable contribution to computational pharmaceutics, bridging theoretical formulation design with practical compounding needs. The platform offers a scalable, cost-effective alternative to traditional stability testing and is already available for use by healthcare professionals. Its implementation in hospital and community pharmacies may help mitigate drug shortages, support formulation standardization, and improve patient care. Future developments will focus on real-time stability monitoring and adaptive learning for enhanced precision. Full article

Infrastructure development in permafrost regions continues to face growing challenges from frost heaves and thaw settlement. The traditional frost heave theory considers that soil freezing is caused by the migration of liquid water in the soil; however, existing engineering practice shows that the migration of water vapor during the freezing process cannot be neglected. Based on the hydrothermal–air migration theory of unsaturated soils and their frost heave mechanism, this study established a coupled hydrothermal–air frost heave model for unsaturated silty clay under unidirectional freezing conditions. The computational model was verified through indoor modelling tests. The entire process of water vapor migration, moisture accumulation, and condensation-induced ice formation in unsaturated silty clay was comprehensively reproduced by numerical simulation. The results showed that the moisture field is redistributed during the freezing process of unsaturated soil. The increase in volumetric ice content in the frozen zone is due mainly to the migration of water vapor. Liquid water and water vapor in the unfrozen zone migrate towards the freezing edge driven by the temperature gradient, where they accumulate, leading to a decrease in the unsaturated pore space and a decrease in the equivalent vapor content. This study’s results can provide theoretical support for frost damage prevention in unsaturated silty clay in permafrost regions. Full article

This study investigates the influence of moisture on the mechanical behavior of fine soil mixtures from the São Luís region, applied as subballast layers in railway track structures. Two samples were analyzed: a non-lateritic sandy soil (NA’, AM03) and a lateritic clayey soil (LG’, AM09). The research included physical and chemical characterization tests, as well as repeated load triaxial tests to determine the resilient modulus and shakedown limits, complemented by numerical simulations using the SysTrain 2.0 software. The samples showed average resilient modulus values of 577 MPa and 638 MPa, respectively. Tests were conducted under optimum moisture content and under moisture 1% above the optimum, induced by capillary rise in compacted samples. The results indicated that under 1% above optimum moisture, the shakedown limits were reduced by up to 50% for AM03 and 25% for AM09, demonstrating greater stability for the lateritic soil. In addition, it was observed that as stress ratios increased, the shakedown limits for both moisture conditions tended to converge. Numerical simulations confirmed the adverse influence of increased moisture on the occurrence of shakedown in both samples. For AM03, the simulations revealed progressive failure under elevated moisture, indicating a more severe stress redistribution within the subballast layer. In contrast, AM09 remained within the shakedown regime under both conditions, although it exhibited higher values of $S_1/S_{1\max }$ under moisture above optimum, suggesting a greater tendency toward plastic creep. These findings highlight the critical importance of moisture control for the sustainable performance of railway substructures. This study contributes to understanding environmental vulnerability in transportation infrastructure and supports the development of more resilient and sustainable railway systems. Full article

The mechanical performance of poly(methyl methacrylate) (PMMA) is highly sensitive to moisture absorption, which induces plasticization and softening. In this study, we investigated the ductilization mechanism of PMMA by incorporating various metal salts with different cations (Li⁺ and Mg²⁺) and controlling water absorption through hygroscopic interactions. A nonequilibrium constitutive model is introduced, in which localized water domains around salt-rich regions gradually diffuse into the PMMA matrix during tensile deformation. The stress–strain behavior is described by combining rigid (dry) and soft (hydrated) matrix components, connected through an internal kinetic variable governed by the strain-dependent diffusion rate. The model successfully reproduces experimental tensile data and captures the transition from brittle to ductile behavior as a function of the moisture content. Notably, Mg salts exhibit stronger water binding and slower moisture redistribution than Li salts, resulting in distinct mechanical responses. These findings provide a mechanistic framework for tailoring the ductility of hygroscopic polymer systems via ion–water–polymer interactions. Full article

Heat storage in compacted soil embankments is a promising technology in energy geotechnics, but its impact on the thermo-hydraulic behavior of unsaturated soils remains insufficiently understood. This paper investigates coupled heat and moisture transfer in unsaturated soil under different thermal conditions using a new bottom-heating method. The thermo-hydraulic response is monitored along the soil column and compared to an isothermal drying test. Variations in suction and water content were analyzed to determine water retention curve and to derive unsaturated hydraulic conductivity using the instantaneous profile method. The water retention curve exhibited deviations under thermal conditions, with reduced water contents observed only at intermediate suctions. Unsaturated hydraulic conductivity decreased significantly at moderate suctions but increased by up to one order of magnitude at high suctions. Heat-driven moisture redistribution was examined through flux calculations, highlighting that vapor-phase transport contributed significantly, up to 88%, to the upward water migration. These findings contribute to a better understanding of thermo-hydraulic interactions in unsaturated soils, which is essential for optimizing thermal storage applications in compacted embankments. Full article

Macrotermes barneyi is a typical fungus-growing termite that forms both monogynous (single queen) and polygynous (multiple queen) colonies in nature. This species influences the local soil fertility in part by redistributing nutrients across the landscape in its habitats. However, how the colony structure of M. barneyi affects nutrient cycling and microbial communities within the nest is not well understood. In this study, we compared the physicochemical properties and microbial communities across nest parts between monogynous and polygynous colonies of M. barneyi. Our results showed that the fungus garden is the most nutrient-rich part of the nest, with higher soil moisture, organic matter, ammonium nitrogen, nitrate nitrogen, available sulfur, available potassium, available silicon, and available boron than other nest parts. Notably, the fungus garden in monogynous colonies had higher nitrate nitrogen, available sulfur, and available silicon than those in the polygynous colonies. The microbial α-diversity in the fungus garden was lower than that in other parts of the nest. β-diversity analysis revealed a clear separation of microbial communities between monogynous and polygynous colonies across nest parts. Furthermore, the relative abundance of functional genes associated with “cell cycle control, cell division, and chromosome partitioning” was higher in the fungus garden of polygynous colonies compared to monogynous colonies. Our results suggest that the fungus garden plays a crucial role in maintaining colony stability in M. barneyi colonies. The rapid depletion of nutrients in the fungus garden to sustain the larger population in polygynous colonies likely influences microbial community dynamics and nutrient cycling. Full article

Chilling injury (CI) during postharvest storage seriously impairs bananas’ quality and marketability. This study systematically investigated CI mechanisms through physicochemical, microstructural, and optical analyses and innovatively developed a hyperspectral imaging (HSI)-based approach for early CI detection. Bananas stored at suboptimal (7 °C) and optimal (13 °C) conditions exhibited distinct physicochemical changes. CI progression was related to increased browning symptoms, an abnormal moisture redistribution (reduced pulp moisture content), and delayed softening. Microstructural analysis revealed membrane destabilization, cellular lysis, intercellular cavity formation, and inhibited starch hydrolysis under chilling stress. Hyperspectral microscope imaging (HMI) captured chilling-induced spectral variations (400–1000 nm), enabling the t-SNE-based clustering of CI-affected tissues. Machine learning models using first derivative (1-st)-processed spectra achieved a high accuracy. Both PLS-DA and RF had a 99% calibration accuracy and 98.5% prediction accuracy for CI classification. Notably, HSI detected spectral signatures of early CI (2 days post-chilling treatment) before visible symptoms, achieving a 100% identification accuracy with an optimized PLS-DA combined with 1-st processing. This study provides a theoretical basis for studying fruit CI mechanisms and a novel nondestructive optical method for early CI monitoring in postharvest supply chains. Full article

Soil salinization significantly jeopardizes agricultural productivity and ecological stability in southern Xinjiang’s oasis regions, highlighting the urgent need to examine its spatial–temporal trends and driving mechanisms for improved resource management. Utilizing soil salinity measurements collected in 2010 and 2023, the current research applied multiple environmental variables processed via the Google Earth Engine (GEE) platform to evaluate the predictive capability of four machine learning algorithms—random forest (RF), Gradient Boosting Decision Tree (GBDT), Classification and Regression Tree (CART), and Support Vector Machine (SVM)—for accurate large-scale salinity mapping. Subsequently, a piecewise structural equation model (piecewiseSEM) was employed to quantitatively analyze the driving factors of soil salinization. Correlation analysis revealed seven critical variables—Red, NDSI, kNDVI, SDI, ET, elevation, and SM—as the most influential among the 41 environmental factors assessed for their impact on soil salinity. The performance evaluation ranked the models as follows: RF > GBDT > SVM > CART, with RF achieving the highest predictive accuracy (R² = 0.756, RMSE = 2.265 g·kg⁻¹, MAE = 1.468 g·kg⁻¹). Between 2010 and 2023, soil salinization severity in the region exhibited a slight overall decrease; however, the extent of this reduction was relatively modest. The proportion of moderately and severely salinized areas declined, accompanied by reduced spatial variability, whereas the extent of mildly salinized soils increased markedly. These findings imply that soil salinity primarily experiences internal redistribution within the surface layers, with limited downward leaching. Evapotranspiration (ET) and soil moisture (SM) were identified as the dominant drivers affecting salinity dynamics during both periods, with the influence of SM becoming more pronounced over time. This trend highlights that in conditions of limited natural variability, human-induced irrigation practices have emerged as the primary regulator of soil salinity levels. The findings of this study provide novel methodologies and data support for the monitoring and prevention of soil salinization in arid regions. Full article

Previous research on soil bacteria focused on refining the nitrogen (N) rates during the wheat (Triticum aestivum L.) growth cycle. Studies concerning how additional and split N topdressing applications can affect wheat rhizobacteria are limited. To address this, a two-year field experiment took the cultivar ‘Gaoyou 2018’ of winter wheat as the experimental material from October 2020 to June 2022. Six nitrogen application regimes were established, including no nitrogen application (T1), single topdressing applications of 120 kg ha⁻¹ (T2) and 80 kg ha⁻¹ (T3) at the jointing stage, and split topdressing applications combining 80 kg ha⁻¹ at jointing with 40 kg ha⁻¹ at the booting stage (T4), the flowering stage (T5), and 10th day post-anthesis (T6). The delayed impacts of the split topdressing time on the rhizobacteria diversity were observed in the second year, with T4 exhibiting a 10.5% higher Chao1 index and 2% greater Shannon diversity than T6. Results from both years indicated that the dominant bacterial phylum compositions in the winter wheat rhizosphere were similar across the nitrogen treatments. The additional N treatments fostered 22.9–27.9% Bacteroidita abundance but diminished 24.0–35.9% Planctomycetota, compared to the thenon-fertilized control (T1). T6 increased the α-Proteobacteria abundance by 15.7–22.0% versus T4, while the N topdressing redistribution to the booting stage increased the MND1 genus abundance in Proteobacteria by 31.3–62.5% compared to T2. Redundancy analysis identified that the rhizosphere pH and soil moisture content were the predominant environmental drivers shaping the winter wheat rhizobacteria. Preliminary findings revealed that split nitrogen application during the jointing and booting stages of winter wheat improved the edaphic micro-environment and modulated the proliferation of beneficial rhizobacteria. However, this change was not transmitted to the yield variation. These results suggest that short-term N management strategies may enhance ecological benefits by intensifying soil–plant–microbe interactions, yet they lack direct agronomic yield advantages. Long-term trials are required to establish causality between rhizosphere microbial community dynamics and crop productivity under split N management regimes. Full article

The meteorology-driven multiscale behavior of snow depth over the Tibetan Plateau was investigated via analyzing the spatio-temporal variability of snow depth over 28 intraseasonal continuous snow cover regions. By employing power spectra and the Kullback–Leibler (K-L) distance, the spectral similarities between snow depth and meteorological factors were examined at scales of 5 km, 10 km, 20 km, and 50 km across seasons from 2008 to 2014. Results reveal distinct seasonal and scale-dependent dynamics: in spring and winter, snow depth exhibits lower spectral variance with scale breaks around 50 km, emphasizing the critical roles of precipitation, atmospheric moisture, and temperature, with lower K-L distances at smaller scales. Summer shows the highest spatial variance, with snow depth primarily influenced by wind and radiation, as indicated by lower K-L distances at 15–45 km. Autumn demonstrates the lowest spatial heterogeneity, with windspeed driving snow redistribution at finer scales. The alignment between spatial variance maps and power spectra implies that snow depth data can be effectively downscaled or upscaled without significant loss of spatial information. These findings are essential for improving snow cover modeling and forecasting, particularly in the context of climate change, as well as for effective water resource management and climate adaptation strategies in this strategically vital plateau. Full article

Forests are complex systems in which subtle variations in terrain can reveal much about plant community structure and interspecific interactions. Despite a wealth of studies focusing on broad-scale environmental gradients, the role of fine-scale topographic nuances often remains underappreciated, particularly in subtropical settings. In our study, we explore how minute differences in microtopography—encompassing local elevation, slope, aspect, terrain position index (TPI), terrain ruggedness index (TRI), and flow direction—affect neighborhood-scale interactions among plants. We established an 11.56-hectare dynamic plot in a subtropical forest at the northern margin of China’s subtropical zone, where both microtopographic factors and neighborhood indices (density, competition, diversity) were systematically measured using 5 m × 5 m quadrats. Parameter estimation and mixed-effects models were employed to examine how microtopography influences plant spatial patterns, growth, and competitive dynamics across various life stages. Our findings demonstrate that aspect and TPI act as key drivers, redistributing light and moisture to shape conspecific clustering, heterospecific competition, and tree growth. Remarkably, sun-facing slopes promoted sapling aggregation yet intensified competitive interactions, while shaded slopes maintained stable moisture conditions that benefited mature tree survival. Moreover, in contrast to broader-scale observations, fine-scale TRI was associated with reduced species richness, highlighting scale-dependent heterogeneity effects. The intensification of plant responses with life stage indicates shifting resource demands, where light is critical during early growth, and water becomes increasingly important for later survival. This study thus advances our multiscale understanding of forest dynamics and underscores the need to integrate fine-scale abiotic and biotic interactions into conservation strategies under global change conditions. Full article

Haloxylon ammodendron plays a pivotal role in combating aeolian desertification and restoring degraded arid ecosystems. Strategic afforestation protocols for this xerophytic species offer dual benefits in ecological stabilization and socioeconomic development, particularly in ecotonal zones between desert and oasis ecosystems, as exemplified by the Jilantai Salt Lake region. This investigation employs allometric scaling analysis to elucidate biomass allocation strategies in H. ammodendron plantations under three distinct silvicultural approaches: soil moisture retention afforestation, water flushing afforestation, and mechanical hole afforestation. Key findings demonstrate that water flushing afforestation treatment induced significant biomass enhancement (total biomass: 1718.69 ± 214.28 g), with phylloclade (photosynthetic branch) and vegetative organ biomass increasing by 29.03% and 60.34%, respectively, compared to conventional methods. Conversely, soil moisture retention afforestation preferentially promoted lignification processes, maximizing biomass allocation to structural components (stems: 15.2% increase) and reproductive structures (inflorescences: 22.7% elevation). Standardized major axis regression revealed differential scaling exponents among organ pairs under varying treatments (stem-phylloclade: 1.798; inflorescence-phylloclade: 1.752; vegetative-reproductive: 1.672; p < 0.001), indicating treatment-specific allometric allocation patterns. Notably, soil moisture retention afforestation induced lateral crown expansion through enhanced meristematic activity in secondary branches (p < 0.01), contrasting with the apical dominance observed in water flushing afforestation and mechanical hole afforestation specimens. These morphological divergences suggest resource allocation trade-offs between vertical exploration and horizontal exploitation strategies. The differential growth trajectories were strongly correlated with edaphic moisture redistribution patterns (R² = 0.83, p < 0.001), as quantified using soil water potential measurements. This study provides mechanistic insights into phenotypic plasticity responses to silvicultural interventions. These findings advance our understanding of allometric growth regulation in a psammophyte and establish an empirical basis for optimizing desert afforestation strategies in arid transitional ecotones. Full article

Eryngium foetidum is a promising crop for diversifying agriculture and supporting sustainable development through nutrient-rich unconventional foods. However, limited knowledge about its seed viability and post-harvest management hinders its commercial scalability. This study explored the effects of post-harvest resting treatments on seed quality and vigor, assessing seeds from whole plants, aerial parts, floral spikes, and umbels after 7 and 14 days of resting. Key metrics included seed yield, purity, moisture content, germination, and vigor were assessed. Results showed that seeds retained on whole plants achieved the highest physical purity (72.2%). Seeds that rested for 7 days exhibited higher germination rates (59%), faster germination (mean germination time of 17 days), and improved seedling establishment (70% emergence) compared to seeds that rested for longer durations. These outcomes highlight the importance of specific post-harvest conditions for optimizing assimilate redistribution enhancing seed quality and seedling performance. This research bridges a critical gap in post-harvest management knowledge for E. foetidum, offering practical insights to improve cultivation practices and promote its adoption as a strategic crop. The findings align with global efforts to advance sustainable and innovative agroecosystems. Further studies under diverse environmental conditions and harvest times are recommended to validate these results and support large-scale implementation. Full article

The construction of roads in saline soil areas usually involves using coarse-grained soil as roadbed fill material; studying the water–vapor–salt migration mechanism in coarse-grained saline soil subgrades is crucial for ensuring the stability of highway infrastructure. In order to clarify the influence of fines content and initial moisture on the water–salt migration and to clarify the water–vapor–salt migration patterns in coarse-grained saline soil, a model test of coarse-grained saline soil was conducted to study the response patterns of external water replenishment, final moisture content, final salt content, and liquid level height of coarse-grained saline soil. The results indicated that the water vapor migration amount only causes a change in the final moisture content, albeit not enough to cause salt redistribution. With increasing initial moisture content in coarse-grained saline soil, the migration characteristics of water vapor are weakened, and it imposes a significant inhibitory effect on liquid water migration at the same time. Increasing fines content in coarse-grained soil significantly inhibits water vapor migration, whereas liquid water migration is promoted. Water and salt accumulate in the liquid and vapor coupling migration mode at different heights. Based on the mechanisms of water vapor and salt transport characteristics, this study proposes a novel roadbed structure, which is vital for ensuring the long-term service performance of coarse-grained saline soil roadbeds in saline soil areas. Full article