Background: Impaired glucose regulation (IGR) represents the prediabetic state and is associated with gut microbiota (GM) dysbiosis and chronic inflammation. Tangning Ziyabitusi Tablet (TZT) is a Chinese Uyghur herbal medicine with preventative and therapeutic effects on diabetes, but its hypoglycemic mechanisms are unclear. Methods: Thirty-six male Wistar rats were divided into the normal diet (ND) and IGR groups. The IGR group was given a high-fat diet (HFD). After the IGR model establishment, the ND group was divided into ND and ND+TZT groups, and the IGR group into IGR and IGR+TZT groups. After 8 weeks of TZT administration, 16S rRNA sequencing and untargeted metabolomics were performed on fecal samples. Mesenteric lymph nodes were also collected, and T lymphocytes separated after rats were sacrificed. Flow cytometry was used to characterize different CD4 + T cell subsets in mesenteric lymph nodes. Finally, we analyzed the correlation between GM and characteristic fecal metabolites. Results: Impaired glucose tolerance and insulin resistance were improved in the IGR+TZT group when compared with the IGR group. Bacterial 16S rRNA sequencing results showed that Sobs and Chao1 indices in the IGR group were significantly decreased, but were increased in the IGR+TZT group. The relative abundance of Bacteroidetes was decreased while the relative abundance of Firmicutes was increased in the IGR group. Adlercreutzia abundance was decreased after TZT administration, while the abundance of Christensenellaceae_R-7_group, norank_f_norank_o_Clostridia_UCG-014, UCG-005, and Eubacterium_nodatum_group was increased in the IGR+TZT group. Lymph node CD4 + T cell proportions in the IGR group were significantly increased, while they were significantly decreased in the IGR+TZT group. Correlation analysis showed that tumor necrosis factor-α, interleukin-6, T helper cells (Th1, Th2, Treg), and insulin had a greater impact on GM community structure. Conclusions: TZT improved glucose tolerance and ameliorated GM dysbiosis in IGR rats. Additionally, TZT significantly modulated CD4 + T cell subset proportions in rat mesenteric lymph nodes and fecal metabolism. Moreover, correlation analysis showed that key microbiota was closely related to IGR indices. Thus, TZT modulated GM composition and immune functions of the intestinal mucosa. We provide useful information for the investigation of active mechanisms and the clinical application of TZT.

The crack distribution characteristics in grinding damage have a significant impact on subsequent polishing efficiency and part strength. Grinding tests were carried out on fused quartz using grinding wheels with different wear states. The results showed that the cracks produced by sharp abrasive grits were mainly near chevron cracks and had no preferred direction. However, the blunt abrasive grits produced near partial cone cracks had a preferred direction. At a depth of 96.7 μm from the surface, the amount of cracks in the range of 50°~90° with an inclination angle between the crack and the cutting direction could reach 88.9%. The statistical results showed that the depth and total length of cracks produced by sharp grits were larger than those produced by blunt grits (the maximum crack depth difference was about 40 μm). Therefore, it was concluded that sharp abrasive grits were not conducive to damage control. The findings of this research enhance our understanding of the formation mechanism of grinding damage.

Understanding the influence mechanism of abrasive/tool wear on machining is the key to realize high-efficiency ultra-precision machining of fused silica. To explore the effect of abrasive/tool wear on ductile machining, the smoothed particle hydrodynamics (SPH) cutting models with different edge radii are established. Through the analysis of equivalent rake angle, hydrostatic pressure, cutting force and maximum principal stress with the Flamant’s formula, the influence of edge radii on ductile-brittle transition (DBT) is discussed for the first time. The simulation results show that when the edge radius increases from less to larger than the cutting depth, the equivalent rake angle changes from positive to negative, and the maximum hydrostatic pressure gradually increases, which is beneficial to promote the ductile processing. Meanwhile, with the rise of edge radius (i.e., abrasive/tool wear), both the cutting force and crack initiation angle increase, while the friction coefficient and normalized maximum principal decrease. When the value of normalized maximum principal stress exceeds 2.702, the crack in the workpiece begins to initiate, and its initiation angle calculated by the Flamant’s formula is in good agreement with the simulation results as well as less than 50°. Finally, the nano-scratch experiment was carried out, and the material removal mechanism and friction coefficient f similar to the simulation were obtained, which further proved the accuracy of SPH model. This study is meaningful for understanding the effect of abrasive/tool wear on the removal mechanism of brittle materials and improving the quality and efficiency of cutting and grinding.