Effects of different inlet velocity on the polishing quality of abrasive flow machining

In order to study the effect of different inlet velocity on the polishing quality of abrasive flow machining, this paper takes the variable diameter pipe as an example. The fluid dynamic pressure and total energy of abrasive particles under coupling field with different inlet velocities were carried out by using computational fluid dynamics software. The results of numerical analysis show that the polishing quality becomes better with the increase of the inlet velocity. At the same inlet velocity, the smaller the pipe diameter is, the higher the polishing quality will be. Therefore, the optimum inlet velocity can be selected by numerical simulation according to the size of the aperture of workpiece in the actual processing, which can provide technical support for the production

Isoparametric surfaces in 3-dimensional de Sitter space and anti-de Sitter space

A spacelike surface $M$ in 3-dimensional de Sitter space $\mathbb{S}^3_1$ or 3-dimensional anti-de Sitter space $\mathbb{H}^3_1$ is called isoparametric, if $M$ has constant principle curvatures. A timelike surface is called isoparametric, if its minimal polynomial of the shape operator is constant. In this paper, we determine the spacelike isoparametric surfaces and the timelike isoparametric surfacesx in $\mathbb{S}^3_1$ and $\mathbb{H}^3_1$

Optimization of sub-grid scale model for abrasive flow machining curved tube based on large eddy simulation

Abrasive flow machining technology is a new type of precision machining technology. Due to its unique rheological properties, it can process any complex structure and size parts to meet the requirements that conventional machining cannot meet. Combined with the turbulent flow characteristics of the abrasive flow, the large eddy simulation numerical method is used to simulate the machining process of the abrasive flow. The influence of different sub-grid scale models on the simulation results is discussed. Taking curved tube as the research object, the static pressure, dynamic pressure and velocity of different sub-grid models are analyzed to find the best sub-grid scale model. Large eddy simulation method is used to simulate the complex flow channel parts, and the best sub-grid scale model suitable for complex flow channels is determined, which reveals the grinding and polishing rule of abrasive flow and provides academic support for future research. Therefore, it has frontier and important research value

Studies on the changes in rectal permeability and intestinal microbiota with developmental age in young rats

IntroductionThe gut contains a diverse array of commensal microorganisms, forming a vital biological barrier within the intestine that contributes to the overall intestinal mucosal barrier. However, research on the rectal barrier during early development remains limited. This study aims to investigate the relationship between intestinal microbiota and rectal barrier function in young rats.MethodsWe evaluated the rectal barrier structure and function in rats at 2-, 4-, and 10-week-old. Methodology included histological analysis, Muc2 expression quantification, immunofluorescence localization of tight junction proteins (ZO-1, Occludin, Claudins), blood glucose monitoring after rectal insulin administration, and 16S rDNA sequencing of rectal microbiota. Spearman correlation analysis was used to explore mechanisms linking age-dependent changes in rectal permeability to microbiota dynamics.ResultsPhysiological rectal permeability was significantly higher in 2-week-old rats compared to 4- and 10-week-old rats (p < 0.01), although systemic biomarkers (LPS, D-LA, and LBP) showed no significant differences. The rectal microbiota exhibited marked age-dependent shifts in composition, α/β-diversity, and metabolic pathways, with increased abundance of beneficial taxa (e.g., Muribaculaceae, Akkermansia) in older rats. Correlation analysis revealed strong associations between reduced permeability, elevated Occludin expression, and microbiota maturation (R = 0.65, p < 0.001).ConclusionThis study demonstrates that age-dependent maturation of the rectal barrier is closely linked to microbiota composition and tight junction protein expression, providing insights into developmental mechanisms and potential strategies for pediatric rectal drug delivery

Characterization of a broad-spectrum antifungal strain, Streptomyces graminearus STR-1, against Magnaporthe oryzae

Fungal diseases such as the devastating rice blast pose severe threats to crop production worldwide. Biological control of crop diseases caused by fungal pathogens is an environment-friendly approach for safeguarding crop production. But the insufficient availability of microbial agents effective against various fungal diseases has hampered the development of green production in crops. In this study, we identified a broad-spectrum antifungal bacterium, Streptomyces graminearus STR-1, showing antagonistic activity to diverse fungal pathogens including Magnaporthe oryzae, Rhizoctonia solani, Fusarium graminearum, Ustilaginoidea virens, and Bipolaris maydis. Its antifungal activity was relatively stable and less affected by temperature and pH. Evaluation of the biocontrol activity of STR-1 revealed that STR-1 prevented and controlled rice blast disease via eliciting plant immunity and suppressing fungal infection-structure development. STR-1 broth extract inhibited spore germination, likely through inhibiting protein synthesis. Combining LC–MS and chromatography analysis of the antimicrobial compounds purified from STR-1 broth extract, together with decoding STR-1 genomic sequence, we identified 4-oxo-4-[(1-phenylethyl)amino]but-2-enoic acid, 1,3,5-Trimethylpyrazole and SMA-1 as the potential main STR-1 secondary metabolites associated with its antifungal effects. This study suggests that bacterial strain STR-1 could be used for identifying highly effective and broad-spectrum secondary metabolites for containing rice blast and other crop diseases. The application of the active compounds offers a promising measure to tackle fungal disease

Supplementation of multi-enzymes alone or combined with inactivated Lactobacillus benefits growth performance and gut microbiota in broilers fed wheat diets.

peer reviewedThe effects of multi-enzymes mixture supplementation or combination with inactivated Lactobacillus on growth performance, intestinal barrier, and cecal microbiota were investigated in broilers at the age of 15-42 days fed a wheat-based diet. A total of 576 broilers (12 broilers/cage; n = 12) were used and divided into four groups and randomly allotted to four experimental diets throughout grower (15-28 days of age) and finisher (29-42 days of age) phases. Diets consisted of a corn-soybean meal-based diet (BD), a wheat-soybean meal-based diet (WD), and WD supplemented multi-enzymes (WED) or combined with inactivated Lactobacillus (WEPD). The results showed that the average daily gain (ADG) and body weight (BW) were reduced in broilers fed WD diet compared with those fed BD diet during the grower period (P < 0.05). Broilers in the WED or WEPD group had higher ADG and BW during the grower period (P < 0.05) and had a lower feed-to-gain ratio (F/G) compared to broilers in the WD group during the grower and overall periods (P < 0.05). Improved expression of intestinal barrier genes (claudin-1, ZO-1, and mucin-2) was observed in WEPD compared to the BD or WD group (P < 0.05). Compared to the BD group, the WD group decreased the abundance of Oscillospira, norank_f__Erysipelotrichaceae, and Peptococcus, which are related to anti-inflammatory function and BW gain. The WD also increased Bifidobacterium and some short-chain fatty acid (SCFA)-producing bacteria (Anaerotruncus, Blautia, and Oscillibacter), and Barnesiella, which were presumed as "harmful microbes" [false discovery rate (FDR) < 0.05]. WED and WEPD groups, respectively, improved Bilophila and Eubacterium_hallii_group compared with those in the WD group (FDR < 0.05). In addition, the Enterococcus abundance was reduced in the WEPD group compared to the WD group (FDR < 0.05). Higher acetate and total SCFA concentrations were observed (P < 0.05) among broilers who received a WD diet. Compared with the WD group, the WED or WEPD group further increased cecal propionate content (P < 0.05) and tended to improve butyrate concentration. These results suggested that supplemental multi-enzymes alone and combined with inactivated Lactobacillus could improve the growth performance based on the wheat-based diet and offer additional protective effects on the intestinal barrier function of broilers