Due to their effectiveness, environmental friendliness, and economic benefits, geosynthetics are increasingly utilized in civil engineering, especially woven geotextiles for soil stabilization reinforcement. Standard strength testing assumes a constant rate of elongation for samples, but in practice, the loading rate of geosynthetics in the field is much lower. Selecting appropriate materials is crucial for the effectiveness and durability of structures. For polymeric materials like woven geotextiles, the strain rate affects their properties. Understanding these properties is essential for safe design and construction. This article explores the potential application of polypropylene geotextiles for soil reinforcement in embankments. The polymer properties are discussed, along with the methodology for strength testing of geosynthetics and the results of the research. The findings allowed for the calculation of the long-term strength of samples at different elongation rates, which was used to verify changes in the factor of safety for a slope model. The highest tensile strength was 33.44 kN/m at a stretching speed of 20 mm/min. At 2 mm/min, it was 30.35 kN/m, and at 0.2 mm/min, it was 28.70 kN/m. These results determined the factor of safety: F = 2.08 for the fastest stretched sample and F = 1.97 for the slowest. Theoretical approaches to understanding changes in strength parameters due to variations in strain rate have been presented, as well as computational approaches using the Bishop method in GEO5 software, based on the results from tensile strength tests.

This study offers a novel investigation into the incremental behavior of granular materials by focusing on the effects of particle elongation on mechanical properties and microstructural evolution. Through a series of Discrete Element Method (DEM) simulations, samples with varying elongation coefficients (n) are systematically analyzed using two strain decomposition methods: the energy dissipation constraint method and the loading cycle method. The results show that as n increases, the strain envelope size decreases, indicating greater stiffness. A 'memory effect' is observed in the elastic strain envelope, suggesting internal rearrangement and partial microstructural recovery in later stages. The plastic strain envelope exhibits distinct patterns that vary with loading conditions, with magnitude decreasing as n increases. Despite identical initial stress states, the orientation of the plastic strain envelope shifts significantly, highlighting the impact of loading history and anisotropy. Notably, the misalignment between the normal direction of the yield surface and the incremental plastic flow direction indicates a non-associated flow rule for the generated granular materials. This misalignment varies with n and loading conditions. The study also reveals a transition from contraction to dilation behavior across different probing states, with increasing n leading to a denser packing of particles with a lower void ratio. As n increases, the anisotropy within the granular assembly becomes more pronounced, leading to a stronger directional dependence of the mechanical response.

Particle shape is an intrinsic characteristic of soil particles that significantly influences mechanical responses. In this investigation, a meticulously calibrated and validated two-dimensional discrete element method (DEM) model of a biaxial shearing test was employed to simulate the shearing response of forty distinct particle shapes. The systematic evolution of particle roundness (R) and aspect ratio (AR) was achieved by utilizing idealized polygonal-shaped particles, aiming to comprehend their effects on the macro and micromechanical behaviors of granular materials. The results suggest that a reduction in R limits free rotations and enhances interlocking, thereby promoting relatively stable force transmission between particles and leading to a monotonic increase in shear strength. However, this effect diminishes as particles become more elongated. Conversely, a decrease in AR from 1.0 (increased elongation) constrains particle rotations, increases the coordination number, and enhances fabric anisotropy initially resulting in increased overall shear strength, reaching a maximum before exhibiting a decreasing trend, indicative of non-monotonic variation. For high elongations, notable fabric anisotropy impedes clear force transmission between particles thus facilitating interparticle sliding and overall strength diminishes. The extent to which AR impacts depends on the angularity feature of particles. Finally, a nonlinear equation has been proposed to predict the variation in critical state shear strength of granular samples, based on the R and AR values of the constituent particles.

The widespread application of copper oxide nanoparticles (CuO NPs) in agricultural production has caused growing concerns about their impact on crops. In this study, wheat root elongation was used to evaluate the toxic effect concentrations of CuO NPs in two soils with differing properties, collected from farmlands in Guangdong (GD) and Shandong (SD) provinces, China. Plant morphological and biochemical properties were also assessed to explore the toxicity mechanism of CuO NPs on wheat seedlings. The root elongation results revealed lower toxic effect concentration values in the plants grown in GD soil than in SD soil. Furthermore, the treatment with CuO NPs at 200 mg Cu kg-1 significantly reduced wheat root and shoot biomass by 35.8% and 15.8%, respectively, in GD soil. Electron microscopy showed that CuO NPs deformed wheat roots and entered leaf cells, causing deformation and damaging the cell structure. The CuO NP treatments also decreased chlorophyll content, increased antioxidant enzyme activity, and increased membrane lipid peroxidation in wheat leaves. The addition of CuO NPs significantly reduced the Zn (by 17.3%) and Fe (by 26.9%) contents in the leaves of plants grown in GD and SD soils, respectively. However, the contents of Cu, Mg, and Mn were increased by 27.4%-52.5% in GD soil and by 17.9%-71.6% in SD soil. These results suggested that CuO NPs showed greater toxicity to wheat plants grown in acidic soil than in alkaline soil and that the adverse effects of CuO NP treatments on wheat seedlings were due to a combination of CuO NPs and released Cu2+.

The damage excessive neodymium (Nd) causes to animals and plants should not be underestimated. However, there is little research on the impact of pH and associated ions on the toxicity of Nd. Here, a biotic ligand model (BLM) was expanded to predict the effects of pH and chief anions on the toxic impact of Nd on wheat root elongation in a simulated soil solution. The results suggested that Nd3+ and NdOH2+ were the major ions causing phytotoxicity to wheat roots at pH values of 4.5-7.0. The Nd toxicity decreased as the activities of H+, Ca2+, and Mg2+ increased but not when the activities of K+ and Na+ increased. The results indicated that H+, Ca2+, and Mg2+ competed with Nd for binding sites. An extended BLM was developed to consider the effects of pH, H+, Ca2+, and Mg2+, and the following stability constants were obtained: logKNdBL = 2.51, logKNdOHBL = 3.90, logKHBL = 4.01, logKCaBL = 2.43, and logKMgBL = 2.70. The results demonstrated that the BLM could predict the Nd toxicity well while considering the competition of H+, Ca2+, Mg2+ and the toxic species Nd3+ and NdOH2+ for binding sites.

Soil contamination by indium, an emerging contaminant from electronics, has a negative impact on crop growth. Inhibition of root growth serves as a valuable biomarker for predicting indium phytotoxicity. Therefore, elucidating the molecular mechanisms underlying indium-induced root damage is essential for developing strategies to mitigate its harmful effects. Our transcriptomic findings revealed that indium affects the expression of numerous genes related to cell wall composition and metabolism in wheat roots. Morphological and compositional analysis revealed that indium induced a 2.9-fold thickening and a 17.5 % increase in the content of cell walls in wheat roots. Untargeted metabolomics indicated a substantial upregulation of the phenylpropanoid biosynthesis pathway. As the major end product of phenylpropanoid metabolism, lignin significantly accumulated in root cell walls after indium exposure. Together with increased lignin precursors, enhanced activity of lignin biosynthesis-related enzymes was observed. Moreover, analysis of the monomeric content and composition of lignin revealed a significant enrichment of p-hydroxyphenyl (H) and syringyl (S) units in root cell walls under indium stress. The present study contributes to the existing knowledge of indium toxicity. It provides valuable insights for developing sustainable solutions to address the challenges posed by electronic waste and indium contamination on agroecosystems.