Granite residual soils (GRS) are often encountered in geotechnical projects in the Guangdong-Hong Kong-Macao Greater Bay Area (briefly written as the Greater Bay Area, or abbreviated as GBA). The rea experiences frequent rainfall, leading to wetting-drying cycles that progressively diminish the shear strength of GRS. This weakening effect is not only significant but also accumulates, exhibiting a direct positive correlation with the number of cycles. Current studies on the soil strength attenuation due to wetting-drying cycles are typically limited to no more than 10 cycles, which is rather insufficient to uncover the long-term water-weakening behaviors and their accumulative impacts on GRS. To address this gap, typical GRS samples were first taken from the GBA and then prepared by making them go through a certain number of wetting-drying cycles (maximum of up to 100). Next, a total of 552 small- and large-scale direct shear tests were conducted to investigate the mechanisms of water-weakening effects on soil internal friction angle, cohesion, and shear strength. The degree of saturation and number of cycles were also examined to see their effects on the cumulation of water weakening. Based on results from the small-scale direct shear tests, a model was developed for assessing the weakening impact of water on soil strength. The accuracy of the model prediction was statistically evaluated. Last, the effectiveness and efficiency of the proposed model were demonstrated by validating against the results from the large-scale direct shear tests.

Flow instability impacts negatively on hydraulic structures. Changes in water pressure or the periodic impact of water flows cause structural damage to channels. The rapid increase in water depth leads to overflows or sprays, which erode soil adjacent to channels. In this study, flow instability was examined through the basis of theories and experiments. The theoretical discriminants for flow instability were inferred by Vedernikov number and the effect of slopes on the Froude number was considered. A rectangular cross- channel was selected for the experiments. The experimental results were compared with theories, it was shown that when the flow conditions were on the margin of instability, the discriminant established by this study is able to accurately determine the occurrence of instability. Through this new discriminant, the discrepancy which appears in traditional method can be avoided. The presented results are ideal for channel design and offer new approaches for flow instability prevention.

Cement mixing techniques are widely used to improve the mechanical properties of weak soils in geotechnical engineering. However, due to the influence of various factors such as material properties, mixing conditions, and curing conditions, cement-mixed soil exhibits pronounced spatial variability which is greater than that of natural soil deposits, introducing additional uncertainty into the measurement and evaluation of its unconfined compressive strength. The purpose of this study is to propose a novel framework that integrates image analysis with Bayesian approach to evaluate the unconfined compressive strength of cement-mixed soil. A portable scanner is used to capture high-quality digital images of cement-mixed soil specimens. Mixing Index (MI) is defined to effectively evaluate mixing quality of specimens. An equation describing the relationship between water cement ratio (W/C) and unconfined compressive strength (qu) is introduced to estimate the strength of uniform specimens. To estimate the strength of non-uniform specimens, the equation is developed by integrating MI with the strength of uniform specimens. The coefficients of equations are obtained using Bayesian approach and Markov Chain Monte Carlo (MCMC) method, which effectively estimating the strength of both uniform and non-uniform specimens, with coefficients of determination (R2) of 0.9858 and 0.8745, respectively. For each specimen, a distribution of estimated strength can be obtained rather than a single fixed estimate, providing a more comprehensive understanding of the variability in strength. Bayesian approach robustly quantifies uncertainties, while image analysis serves as a convenient and non-destructive method for strength evaluation, providing accurate method for optimizing the mechanical properties of cement-mixed soil.

Debris flows are catastrophic mass movements with significant social and environmental consequences, particularly in the Western Himalayas. Understanding the rheological properties of debris flow material is crucial for accurately modeling their behavior and predicting their impacts. In this study, rheological parameters such as yield stress and viscosity were determined through extensive laboratory testing using a parallel plate setup in a rheometer. Reconstituted soil samples from the debris flow zone were prepared using an optimized sampling approach to vary the solid volume concentration and water content (w/c). Experimental results revealed non-Newtonian behavior for all tested compositions, which closely aligned with the Herschel-Bulkley rheological model. The Herschel-Bulkley parameters were subsequently used to calibrate a smooth particle hydrodynamics (SPH) model in the open-access DualSPHysics tool. The results showed that water content and silt concentration played a significant role in influencing the rheology, with finer particles exhibiting higher viscosity and shear stress compared to coarser particles. The SPH simulations effectively replicated the flow behavior observed during the Kotrupi debris flow event (2017), providing insights into flow dynamics, such as velocity and shear distribution. This integration of experimental rheology and numerical modeling advances our understanding of debris flow mechanics and highlights the importance of incorporating rheological calibration in predictive debris flow models.

Lakes are commonly accepted as a sensitive indicator of regional climate change, including the Tibetan Plateau (TP). This study took the Ranwu Lake, located in the southeastern TP, as the research object to investigate the relationship between the lake and regional hydroclimatological regimes. The well-known Budyko framework was utilized to explore the relationship and its causes. The results showed air temperature, evapotranspiration and potential evapotranspiration in the Ranwu Lake Basin generally increased, while precipitation, soil moisture, and glacier area decreased. The Budyko space indicated that the basin experienced an obviously drying phase first, and then a slightly wetting phase. An overall increase in lake area appears inconsistent with the drying phase of the basin climate. The inconsistency is attributable to the significant expansion of proglacial lakes due to glacial melting, possibly driven by the Atlantic Multidecadal Oscillation. Our findings should be helpful for understanding the complicated relationships between lakes and climate, and beneficial to water resources management under changing climates, especially in glacier basins.

Cadmium (Cd) is a pervasive phytotoxic metal which deteriorates soil quality, affecting crops and creating adverse effects on the environment, food safety, and human health. Cd in soil poses negative effects on plants at the physiological, structural, and molecular level. Application of silicon (Si) can reduce Cd accumulation by suppressing Cd uptake in plants, while spermidine (Spd) alleviates Cd toxicity through improved antioxidant capacity. However, their combined effects on antioxidant system and endogenous polyamines (PAs) level in Cd-stressed plants and the underlying antioxidative defense mechanism are poorly understood. Salix matsudana Koidz. is a fast-growing tree species with high Cd tolerance, making it potentially suitable for phytoremediation. Here, the S. matsudana seedings were subjected to 50 mu M Cd stress with or without addition of 1.5 mM sodium silicate and 0.1 mM Spd. Following that, the non-enzymatic/enzymatic antioxidants, stressed-related genes and endogenous PAs levels were determined. The results showed that Cd stress suppressed the growth traits of S. matsudana while increasing reactive oxygen species (ROS) and malondialdehyde (MDA) accumulation in the leaves, which also showed heightened Cd levels. However, exogenous application of Si and Spd increased activities of antioxidative enzymes and ameliorated the Cd-induced oxidative damage. Moreover, combined treatment with Si and Spd showed higher glutathione (GSH) and GSH/GSSH (oxidized glutathione) ratio compared to their individual applications. The results provided sufficient evidence regarding the synergistic effect of Si and Spd in the amelioration of Cd-induced oxidative stress in S. matsudana seedlings.

Previous theoretical studies on the deformation of shield tunnels induced by foundation pit excavation generally consider the stratum as a linear elastic body, which seldom take the irregular construction boundary into account. Meanwhile, Curved beam theory and Timoshenko beam theory are less applied in the study of tunnels. This paper provides an analytical method to predict the displacements of small curved tunnels caused by deep excavation with time effects. Firstly, by introducing the fractional derivative Merchant model, a mechanical approach is proposed for analyzing the structural deformation of neighboring tunnels induced by foundation pit excavation. The parameters of viscoelastic soils are further derived in the Laplace domain based on time variability properties. Secondly, the additional stress field on existing small curvature tunnels is solved with theory of viscoelastic Mindlin solution and load reduction in foundation pits. Moreover, a deformation calculation model for curved shield tunnels is established by applying Pasternak foundation and Timoshenko beam theory. The time domain solutions for the radial and vertical deformations of small curvature tunnels are then derived by finite difference method along with Laplace positive and inverse transforms. In addition, the engineering measured data and three-dimensional numerical simulation solutions are compared with the analytical solution to verify relatively accuracy. Finally, sensitivity analyses are performed for parameters such as the buried depth of tunnels, minimum clear distance, fractional order, excavation method and creep time.

This paper employs the discrete element method (DEM) to simulate the nanoindentation creep of calcium- silicate-hydrate (C-S-H), focusing on indentation deformation, particle interactions, and stress transmission paths. The Rate Process Theory (RPT), previously utilized in the creep modeling of cohesive soils and other granular materials, is proposed to simulate C-S-H creep. Due to the nanometer size of C-S-H particles, the critical time step in DEM simulations is very small. Therefore, a time-scaling algorithm is used to match the DEM simulation time with the physical time in laboratory tests, accelerating the simulation time by a factor of 1 x 108. C-S-H particle assemblies with specific packing densities are generated using Particle Flow Code (PFC3D, version 5.0), with coordination numbers and cohesion forces controlled by the stress-servo of PFC walls. Virtual nano- indentations using a Berkovich indenter are conducted on C-S-H particle assemblies with three different packing densities (0.74, 0.64, and 0.58), followed by parameters calibration. Results show that the DEM + RPT method can capture the scaling relations between the indentation modulus, hardness, and contact creep modulus of C-S- H particle assemblies and the packing density. Furthermore, DEM simulations reveal particle rearrangement under Berkovich and flat-tip indenters, highlighting that different indenter types lead to distinct creep kinetics in C-S-H, with the Berkovich indenters experimentally capturing long-term creep and flat-tip indenters measuring short-term creep.

With increasing global environmental awareness and concerns about food safety, biodegradable active packaging has garnered widespread attention. In this study, the stability and bioactivity of tea polyphenol (TP) were enhanced through the preparation of TP-ferric nanoparticles (TP-Fe NPs) using metal-polyphenol ion coordination. Moreover, the introduction of Fe ions can further enhance the antibacterial effects of TP-Fe NPs. Using the hydrogen bonding between konjac glucomannan (KGM) and zein to enhance the hydrophobicity and mechanical properties of the film. By employing KGM and zein as the matrix, we incorporated TP-Fe NPs as active fillers to create multifunctional active packaging films. This study aimed to meet the needs of food safety and sustainable development goals. The resulting film exhibited excellent water resistance (water contact angle: 117.73(degrees)), mechanical strength (tensile strength: 21.82 MPa, elongation at break: 94.30 %), ultraviolet-shielding ability (>99 %), biodegradability (5 days in soil), and antioxidant (>85 %) and antibacterial (>99 %) properties. Moreover, the film significantly reduced strawberry decay and extended its shelf life by 10 days. These findings provide new insights into the application of nanomaterials in active packaging, highlighting their potential and advantages in food preservation.

Mercury is a significant environmental pollutant and public health threat, primarily recognized for its neurotoxic effects. Increasing evidence also highlights its harmful impact on the cardiovascular system, particularly in adults. Exposure to mercury through contaminated soil, air, or water initiates a cascade of pathological events that lead to organ damage, including platelet activation, oxidative stress, enhanced inflammation, and direct injury to critical cells such as cardiomyocytes and endothelial cells. Endothelial activation triggers the upregulation of adhesion molecules, promoting the recruitment of leukocytes and platelets to vascular sites. These interactions activate both platelets and immune cells, creating a pro-inflammatory, prothrombotic environment. A key outcome is the formation of platelet-leukocyte aggregates (PLAs), which exacerbate thromboinflammation and endothelial dysfunction. These processes significantly elevate cardiovascular risks, including thrombosis and vascular inflammation. This study offers a comprehensive analysis of the mechanisms underlying mercury-induced cardiotoxicity, focusing on oxidative stress, inflammation, and cellular dysfunction. [GRAPHICS] .