The proportional strain loading test is a prevalent method for investigation diffuse instability. The majority of current research concentrates on narrowly graded materials, with relatively less focus on binary mixtures under proportional strain loading. Therefore, a series of numerical tests have been conducted using the discrete element method to study the influence of fine content and strain increment ratio on the binary mixtures. The test results show that the fine content of binary mixtures is intimately connected to the critical strain increment ratio which precipitate a transition from stability to instability. Binary mixtures characterized by a low stress ratio at the onset of instability also demonstrate a heightened sensitivity to shifts in strain increment ratio. The macroscopic responses, such as the stress ratio at the onset of instability, shear strength, and pore water pressure, exhibit different trends of variation with the fine content compared to microscopic responses, including coordination number, friction mobilization index, and the proportion of sliding contacts. Furthermore, the anisotropy coefficient is introduced to dissect the sources of anisotropy at onset of instability, revealing that strong contact fabric anisotropy can mirror the evolution of the stress ratio. The stress ratio at onset of instability is predominantly influenced by anisotropy in contact normal and normal contact force.

Loose granular materials may also exhibit instability behaviors similar to liquefaction under drained conditions, commonly referred to as diffuse instability, which can be studied through constant shear drained (CSD) tests. So far, the research on CSD in binary mixtures is still insufficient. Therefore, a series of numerical tests using the discrete element method (DEM) were conducted on binary mixtures under CSD path. The possible model of instability is categorized into type I and type II, type I instability occurs prior to reaching the critical state line (CSL), whereas type II instability occurs after exceeding the CSL. The study analyzes the macroscopic instability behavior and the impact of fine content (FC) on macroscopic instability behavior. The numerical results show that as FC increases, the slope of the instability line (IL) increases initially and then falls in the p-q plane. In the e-p plane, the IL decreases initially and then ascends. The instability type of the binary mixtures is influenced not only by relative density but also by FC. The stability index increased first and then decreased with the increase of FC. The microscopic origin of binary mixtures instability is explored by investigating the fabric-stress relationship. The collapse of the weak contact sub-network triggers the specimen instability, while the strong contact sub-network dictates the difficulty of achieving instability. FC influences the evolution of fabric anisotropy of the strong and weak contact networks, thereby controlling the macroscopic instability behavior of binary mixtures.

There is growing concern that sprayed neonicotinoid pesticides (neonics) persist in mixed forms in the environmental soil and water systems, and these concerns stem from reports of increase in both the detection frequency and concentration of these pollutants. To confirm the toxic effects of neonics, we conducted toxicity tests on two neonics, clothianidin (CLO) and imidacloprid (IMD), in embryos of zebrafish. Toxicity tests were performed with two different types of mixtures: potential mixture compounds and realistic mixture compounds. Potential mixtures of CLO and IMD exhibited synergistic effects, in a dose-dependent manner, in zebrafish embryonic toxicity. Realistic mixture toxicity tests that are reflecting the toxic effects of mixture in the aquatic environment were conducted with zebrafish embryos. The toxicity of the CLO and IMD mixture at environmentally-relevant concentrations was confirmed by the alteration of the transcriptional levels of target genes, such as cell damage linked to oxidative stress response and thyroid hormone synthesis related to zebrafish embryonic development. Consequently, the findings of this study can be considered a strategy for examining mixture toxicity in the range of detected environmental concentrations. In particular, our results will be useful in explaining the mode of toxic action of chemical mixtures following short-term exposure. Finally, the toxicity information of CLO and IMD mixtures will be applied for the agricultural environment, as a part of chemical regulation guideline for the use and production of pesticides.