Freeze-thaw cycles (FTC) influence soil erodibility (K-r) by altering soil properties. In seasonally frozen regions, the coupling mechanisms between FTC and water erosion obscure the roles of FTC in determining soil erosion resistance. This study combined FTC simulation with water erosion tests to investigate the erosion response mechanisms and key drivers for loess with varying textures. The FTC significantly changed the mechanical and physicochemical characteristics of five loess types (P < 0.05), especially reducing shear strength, cohesion, and internal friction angle, with sandy loam exhibiting more severe deterioration than silt loam. Physicochemical indices showed weaker sensitivity to FTC versus mechanical properties, with coefficients of variation below 5 %. Wuzhong sandy loess retained the highest K-r post-FTC, exceeding that of the others by 1.04 similar to 2.25 times, highlighting the dominant role of texture (21.37 % contribution). Under different initial soil moisture contents (SMC), K-r increased initially and then stabilized with successive FTC, with a threshold effect of FTC on K-r at approximately 10 FTC. Under FTC, the K-r variation rate showed a concave trend with SMC, turning point at 12 % SMC, indicating that SMC regulates freeze-thaw damage. Critical shear stress exhibited an inverse response to FTC compared to K-r, displaying lower sensitivity. The established K-r prediction model achieved high accuracy (R-2 = 0.87, NSE = 0.86), though further validation is required beyond the design conditions. Future research should integrate laboratory and field experiments to expand model applicability. This study lays a theoretical foundation for research on soil erosion dynamics in freeze-thaw-affected areas.

Liquefaction resistance and post-liquefaction shear deformation are key aspects of the liquefaction behavior for granular soil. In this study, 3D discrete element method (DEM) is used to conduct undrained cyclic triaxial numerical tests on specimens with diverse initial fabrics and loading history to associate liquefaction resistance and post-liquefaction shear deformation with the fabric of granular material. The influence of several fabric features on liquefaction resistance is first analyzed, including the void ratio, particle orientation fabric anisotropy, contact normal fabric anisotropy, coordination number, and redundancy index. The results indicate that although the void ratio and anisotropy strongly influence liquefaction resistance, the initial coordination number or redundancy index can uniquely determine liquefaction resistance. Regarding post-liquefaction shear deformation, the above quantities do not dictate the shear strain induced after initial liquefaction. Instead, the mean neighboring particle distance (MNPD), a fabric measure previously introduced in 2D and extended to 3D in this study, is the governing factor for post-liquefaction shear. Most importantly, a unique relationship between the initial MNPD and ultimate saturated post-liquefaction shear strain is identified, providing a measurable state parameter for predicting the post-liquefaction shear of sand.

The influence of seismic history on the liquefaction resistance of saturated sand is a complex process that remains incompletely understood. Large earthquakes often consist of foreshocks, mainshocks, and aftershocks with varying magnitudes and irregular time intervals. In this context, sandy soils undergo two interdependent processes: (i) partial excess pore water pressure (EPWP) generation during foreshocks or moderate mainshocks, where seismic loadings elevate EPWP without causing full liquefaction and (ii) incomplete EPWP dissipation between seismic events due to restricted drainage. These processes leave behind persistent residual EPWP, reducing the liquefaction resistance during subsequent shaking. A series of cyclic triaxial tests simulating these mechanisms revealed that liquefaction resistance increases when the EPWP ratio r(u) < 0.6-0.8 (peaking at r(u) similar to 0.4) but decreases sharply at higher r(u). Crucially, EPWP generation during seismic loading plays a dominant role in resistance evolution compared to reconsolidation effects. Threshold lines (TLs) mapping r(u), the reconsolidation ratio (RR), and peak resistance interval (the range of r(u) where the peak liquefaction resistance is located) indicates that resistance decreases above TLs and increases below them, with higher cyclic stress ratios (CSR) weakening these effects. These findings provide a unified framework for assessing liquefaction risks under realistic multi-stage seismic scenarios.

This study explores the effectiveness of soft viscoelastic biopolymer inclusions in mitigating cyclic liquefaction in loosely packed sands. This examination employs cyclic direct simple shear testing (CDSS) on loose sand treated with gelatin while varying the gelatin concentration and the cyclic stress ratio (CSR). The test results reveal that the inclusion of soft, viscoelastic gelatin significantly reduces shear strain and excess pore pressure during cyclic shear. Liquefaction potential, defined as the number of cycles to liquefaction (NL) at an excess pore pressure ratio (ru = Delta u/sigma ' vo) of 0.7, is substantially improved in gelatin-treated sands compared to gelatin-free sands. This improvement in liquefaction resistance is more pronounced as the inclusion stiffness increases. Furthermore, the viscoelastic pore-filling inclusion helps maintain skeletal stiffness during cyclic shearing, resulting in a higher shear modulus in gelatin-treated sand in both small and large-strain regimes. At a grain scale, pore-filling viscoelastic biopolymers provide structural support to the skeletal frame of a loosely packed sand. This pore filler mitigates volume contraction and helps maintain the effective stress of the soil structure, thereby reducing liquefaction potential under cyclic shearing. These findings underscore the potential of viscoelastic biopolymers as bio-grout agents to reduce liquefaction risk in loose sands.

Rice bakanae disease is a soil-borne disease mainly caused by Fusarium fujikuroi, which seriously damages the yield and quality of rice. Phenamacril targets Myosin-5, thereby inhibiting its ATPase activity to exert an antifungal effect, demonstrating significant bioactivity against Fusarium species. However, the resistance of Fusarium fujikuroi field populations to phenamacril in Jiangsu Province in recent years remains unclear. In this study, a total of 223 Fusarium fujikuroi isolates were collected in Jiangsu Province from 2022 to 2023, with the resistance frequency increase from 25.88 % to 49.28 %. Additionally, a novel mutation type (S420I) in FfMyosin-5 was identified and confirmed by genetic transformation. The compound fitness index (CFI) revealed that the fitness of FfMyosin5(S420I) point mutants (1 x 10(5) < CFI <= 2 x 10(5)) was significantly lower than sensitive strain (CFI = 10.26 x 10(5)) in terms of mycelial growth rate, conidia production and conidia germination. In summary, the S420I mutation in FfMyosin-5 induces resistance to phenamacril while also decreased the fitness of Fusarium fujikuroi.

Alkali-activated concrete (AAC) is a focal point in green building material research due to its low carbon footprint and superior performance. This study seeks to enhance the impact resistance of recycled aggregate concrete (RAC) by elucidating the synergistic mechanisms of alkali activation, nano-modification, and fiber reinforcement. To this end, four mix designs, incorporating NaOH and NaOH-Na2SiO3 systems with 2 % nano-SiO2(NS), were developed and assessed through setting time, compressive strength, drop hammer impact tests, and XRD/ SEM analyses. The NaOH-Na2SiO3 system exhibited a 23.5 % increase in compressive strength over NaOH, achieving 28.41 MPa, while NS refined pore structures, elevating strength to 32.2 MPa; XRD/SEM analyses confirmed mechanisms of pore refinement and interfacial enhancement. In the optimized system, the NT12-C5 formulation, incorporating polypropylene fiber (PPF) and recycled carbon fiber (RCF), exhibited superior impact resistance, with NS enhancing interfacial bonding between carbon fiber and the matrix, resulting in a 47.8 % increase in initial crack impact energy. The Weibull model validated the reliability of impact performance. Furthermore, life cycle assessment revealed that Soil Solidification Rock Recycled aggregate concrete (SSRRAC) substantially reduced carbon emissions compared to ordinary Portland cement (OPC), while maintaining competitive economic costs. This study's innovations include: (1) synergistic optimization of low-carbon AAC performance using NaOH-Na2SiO3 and NS; (2) optimized PPF/RCF formulations promoting the reuse of waste carbon fiber; and (3) application of the Weibull model to overcome conventional statistical constraints. Collectively, these findings establish a theoretical and practical foundation for the global development of sustainable building materials.

The stress state and density of soil have been considered as the key factors to determine the liquefaction resistance. However, the results of seismic liquefaction case histories, laboratory tests and centrifuge model tests show that the fabric characteristics also influence liquefaction resistance, even more significantly than the contributions of stress state and density. In this study, anisotropic specimens with different consolidation histories were prepared using the 3D Discrete Element Method (DEM) to investigate the influence of fabric characteristics on the mechanical behavior of granular materials and the underlying mechanisms. The simulations revealed that under monotonic shear conditions, horizontally anisotropic specimens exhibited strain hardening and dilatancy characteristics, as well as higher peak strength. Under cyclic shear condition, the normalized liquefaction resistance of the specimens showed a strong linear relationship with the degree of anisotropy, independent of confining pressures and density. Microscopic results indicate that the fabric arrangement aligned with the loading direction leads to the evolution of the mechanical coordination number and average contact force in a manner favorable to resisting loads, which is the underlying mechanism influencing macroscopic mechanical properties. Additionally, the evolution patterns of contact normal magnitude and angle in anisotropic granular materials under cyclic loading conditions were also analyzed. The results of this study provided a new perspective on the macroscopic mechanical properties and the evolution of the microstructure of granular soils under anisotropic conditions.

Cherry blossom crown gall has caused serious damage to plant growth, and is highly contagious and extremely difficult to control. The antagonism of pathogens by rhizosphere bacteria has attracted widespread attention. However, there is still limited research on the cherry blossom crown gall. In this study, we explored the control effect of rhizosphere bacteria Pseudomonas aurantiaca ST-TJ4 on cherry blossom crown gall. We also investigated the long-term survival status of ST-TJ4 in the cherry blossom roots and the induction of plant defense resistance. The results showed that ST-TJ4 had obvious inhibition effect on the population of Agrobacterium tumefaciens, which could reduce the number of A. tumefaciens by 70% to 90%, and its population kept the advantage in the rhizosphere soil and cherry blossom roots. The incidence of crown gall in the therapy group and the prevention group was reduced by 37.5% and 50%, respectively, and the disease index was reduced from 80 to 20 and 10, respectively. At the 150th day, ST-TJ4 could still be isolated from the rhizosphere soil and root surface, indicating that ST-TJ4 could survive in soil for a long time and had long-term performance. Compared with the control group, the therapy group and prevention group could reduce the levels of H2O2, malondialdehyde (MDA) and the oxidative damage, and up-regulated the expression of active oxygen-related genes DHAR1, SOD1, GR1 and CAT to activate defense response. On the other hand, it could up-regulate the expression of SA1, SA2 and JA1 genes related to the induction of salicylic acid (SA) and jasmonic acid (JA), and lead to the increase of SA hormone level. Collectively, P. aurantiaca ST-TJ4 had the potential to be applied for biocontrol of cherry blossom crown gall by reducing root pathogen colonization and inducing plant resistance.

Soil organisms are key to plant growth and ecosystem functions. Earthworms (EWs) enhance soil and indirectly affect plant growth, while their cutaneous excreta (CEx) contain bioactive compounds capable of eliciting plant responses. However, their role in plant immunity is still not well understood. We hypothesized that EWs and their CEx enhance plant defense against foliar pathogens by activating induced resistance. To test this, we evaluated the effect of Eisenia fetida and their CEx on Solanum lycopersicum (tomato), focusing on growth, physiology, and defense response against Botrytis cinerea. Plants were exposed to EWs, CEx, or water (control), followed by B. cinerea infection after two weeks. Gene expression of defense markers was assessed at 24 and 48 h post-inoculation (hpi), while physiological parameters and disease severity were evaluated at 72 hpi. EWs increased shoot biomass compared to CEx, while both treatments reduced root dry weight, suggesting a possible shift in resource allocation. CEx significantly reduced B. cinerea-induced leaf damage and showed a trend for flavonoid accumulation, a known marker of induced resistance. Both treatments, EWs and CEx, activated the jasmonic acid (JA) signaling pathway, with CEx specifically upregulating genes involved in fungal pathogen defense, sustaining their expression over time. The present study offers, for the first time, clear evidence that EW derived CEx can induce resistance by stimulating plant defense responses. Further biochemical, transcriptomic, and metabolomic analyses are needed to confirm indirect results, along with field validation. Nonetheless, the findings underscore the crucial role of soil biodiversity in enhancing crop resilience.

There are currently two main criteria to identify the triggering time of soil liquefaction, namely when the excess pore water pressure reaches vertical effective overburden stress or the double-amplitude axial strain reaches 5 %. However, several researchers have pointed out that the excess pore water pressure may not reach confining pressure at some certain conditions, and the cycle numbers reaching liquefaction obtained by adopting two criteria for calcareous sand specimens are inconsistent, which may lead to overestimation or underestimation of the liquefaction resistance of calcareous sand. Therefore, this study introduces a parameter with physical meaning, secant shear modulus to evaluate the liquefaction potential of soil. To do that, a series of undrained shear tests were conducted on three types of sand. Firstly, the experimental results demonstrated that the difference in cycle numbers to liquefaction obtained by the two criteria increases with the increase of relative density. In addition, the study found that the degradation law of secant shear modulus with the number of cycles is not affected by loading conditions, initial state of soil, and soil type. On this basis, based on the relationship between secant shear modulus gradient and pore pressure ratio, it is highlighted that the liquefaction process can be quantitatively divided into three stages and the moment of liquefaction triggering can be correctly identified. Finally, the proposed liquefaction criterion is compared with widely used traditional criteria and latest apparent viscosity-based criterion, and the results showed that the liquefaction resistance obtained by the proposed criterion was more conservative, which benefits for reducing the occurrence of large strain development.