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Mycotoxin contamination of rice (Oryza sativa), especially that from aflatoxins (AFTs), is one of the greatest chemical hazards to humans and animals. However, few studies have investigated the relationships between fungal communities and mycotoxin contamination of rice grains. In the present study, we collected rice grain samples from 10 provinces in the northeastern (NE), southeastern (SE), and southwestern (SW) regions of China, encompassing the major rice-producing areas of China. The Fungal diversities of rice grain were significantly different among different regions and significantly higher in the SE and SW regions compared to the NE region. Geographic location was highly associated with fungal community alpha and beta diversity differences. Environmental variables determined the distribution of fungal communities, with mean winter temperature (MWT), mean annual precipitation (MAP), harvest mean wind speed (HWS), and grain moisture (GM) being the most important factor shaping the fungal communities, and the higher HWS could significantly reducing the abundance of aflatoxigenic fungi and aflatoxins. The Aspergillus flavus and Aspergillus parasiticus were defined as the major AFT-producing fungal taxa observed in the SE and SW region communities. The NE region exhibited a lower risk of AFT contamination due to its much lower prevalence of toxigenic fungi. Furthermore, keystone taxa of co-occurrence network analyses indicated that species belonging to the genera Clonostachys, Cryptococcus, Hannaella, Leptosphaerulina, Leptosphaeria, Phaeosphaeria, Sarocladium, Sphaerulina, Wallemia and Ustilaginoidea exhibited abundances that were negatively correlated with AFT-producing fungal abundances and could potentially inhibit the growth of AFT-producing fungi. The results could potentially provide important data for the strategic guidance of local rice grain storage in order to better control toxin contamination and improve grain quality.

In order to investigate the effect of the structural layout of multilayered coatings on its mechanical behavior, a three-dimensional elastic field solution is developed for multilayered solids subjected to surface point contact loading, which is converted from the elastic field solution in frequency domain by using a numerical conversion algorithm. The elastic field solution in frequency domain is obtained by numerically solving a group of linear equations involving the unknown constants in the general elastic field solution of layered material that is obtained by using Fourier integral transform technique. The present solution is validated by comparing with the exact analytical solution for uncoated solids and finite element solution for solids coated with 30 layers. Lastly, the effect of structural layout of multilayered coatings is further investigated with present solution. The result shows that the gradient structural layout with elasticity modulus decreasing gradually from the top layer to the substrate, which is preferable to a larger friction coefficient for multilayered solids subjected to surface line contact loading, is preferable for a smaller friction coefficient &lt, 0.1 for multilayered solids subjected to surface point contact loading, and the gradient structural layout with elasticity modulus increasing first in the top layers and then decreasing in the bottom layers, which is preferable to a smaller friction coefficient for multilayered solids subjected to surface line contact loading, is preferable for a friction coefficient &gt, 0.2.