A modified laser ablation-isotope ratio mass spectrometry method for in situ analysis of sulfur isotope composition of sulfides.

RATIONALE: A novel laser ablation-isotope ratio mass spectrometry (LA-IRMS) method for in situ analysis of sulfur isotopes in sulfides has been developed. Instead of the in situ reaction applied by the traditional laser microprobe, the analyte gas preparation in this method is separated temporally and spatially from the LA, resulting in improved precision and accuracy. METHODS: Our LA-IRMS system combines an ultraviolet LA system, an elemental analyzer (EA), a custom-built cryogenic concentration system, a continuous-flow interface, and an IRMS. The sulfide aerosol particles generated from LA were transferred by a helium carrier gas from the ablation cell into the reaction tube and were then converted into SO2 . Subsequently, SO2 was enriched in two cold traps and was finally introduced into the ion source of the IRMS through the continuous-flow interface. RESULTS: We measured three synthetic and four natural sulfide reference materials to test the performance of this method. Precisions of ±0.25‰-±0.48‰ and ±0.32‰-±0.64‰ (1SD, n = 5) for δ34 S values of synthetic and natural sulfide standards can be obtained for spot sizes ranging from 64 to 80 µm. Measured values and their recommended values showed a good linear relationship (R2 within 0.998 and 0.9995) with the slope of approaching unity (within 1.0509 and 1.1313). CONCLUSIONS: Data from the measurement of reference materials showed that the precision and accuracy of our method were satisfactory. This method is a powerful tool for in situ sulfur isotope measurement of sulfides and can be further applied to in situ carbon and oxygen isotope analyses.

Numerical simulation research on thermal insulation performance of composite heat-insulation zone structure in hydrothermal high-temperature mine.

In hydrothermal high-temperature abnormal mines, the composite heat-insulation zone structure, formed through a combination of guniting and grouting, serves to mitigate heat dissipation from the surrounding rock into the airflow. To comprehensively understand the thermal insulation performance of the composite heat-insulation zone structure, this study employs numerical simulation to analyze the following aspects: the variation in the temperature field within the surrounding rock of the roadway without insulation, the influence of structural parameters of the composite heat-insulation zone on temperature distribution in the surrounding rock of the roadway, and the thermal insulation effectiveness of the composite heat-insulation zone with varying structures. The findings indicate that the temperature distribution within the surrounding rock of the roadway lacking a heat-insulation zone is relatively uniform. However, as ventilation time extends, the heat regulation zone within the surrounding rock gradually extends deeper, ultimately forming an elliptical cooling area. The composite heat-insulation zone structure effectively mitigates heat transfer from deeper surrounding rock to the roadway wall, consequently altering the scope of the roadway's heat regulation zone. Enhancing the thermal insulation performance of the composite heat-insulation zone structure can be achieved by increasing the thickness of the thermal insulation layer, adjusting grouting rate and depth, and reducing the thermal conductivity of insulation materials. The thermal insulation effectiveness of the thermal insulation layer surpasses that of the grouting layer, with its performance primarily influenced by the thermal conductivity of the materials used. Simulation results demonstrate that the composite heat-insulation zone structure reduces the maximum heat flux on the roadway wall from 47.4 to 37.7 W/m2, resulting in a 20% reduction in heat transfer from deeper surrounding rock. These findings offer valuable insights for implementing thermal insulation techniques in hydrothermal high-temperature anomaly mines.

Integration of transcriptome and whole-genome re-sequencing analyses reveal growth-related candidate genes in Procambarus clarkii.

Growth is a crucial economic trait of all aquaculture species. It is important to explore the molecular regulation on growth, which could help improve the growth rate of species. Mining the growth-related genes is the foundation for revealing its molecular regulation on growth. Presently, the molecular regulation of growth in Procambarus clarkii is not clear, and the study on exploring growth-related genes is limited. In this study, RNA-Seq was used to compare gene expression profiles of the individuals with different growth rates involved in four groups including Big Male (BM), Big Female (BF), Small male (SM), and Small Female (SF) from one P. clarkii family, and the analyses were performed in combination with sex. Meanwhile, whole-genome resequencing data was used to get growth-specific SNP (Single Nucleotide Polymorphism)/InDel (Insertion/Deletion) sites information. Totally, we identified 16,127 genes, of which 9065 were successfully annotated in the GO database. Among these, 1328 DEGs were identified in BM vs. SM, with 357 up-regulated and 971 down-regulated. Additionally, 3507 DEGs were identified in BF vs. SF, with 241 up-regulated and 3266 down-regulated. 96 DEGs were up-regulated and 820 DEGs were down-regulated in Growth-related Group. The expression levels of nine DEGs were validated by RT-qPCR to verify the analysis results of sequencing. 684,040 growth-related SNPs and 182,050 growth-related InDels were obtained after screened. These findings provide candidate growth-related genes and growth-specific SNP/InDel sites for regulation of growth traits in P. clarkii, and new insight into the molecular regulation of P. clarkii growth.

Astragalus polysaccharides-induced gut microbiota play a predominant role in enhancing of intestinal barrier function of broiler chickens.

BACKGROUND: The intestinal barrier is the first line of defense against intestinal invasion by pathogens and foreign antigens and is closely associated with the gut microbiota. Astragalus polysaccharides (APS) have a long history of use in traditional Chinese medicine owing to its protective properties against intestinal barrier function. The mechanism of APS-induced gut microbiota enhancing intestinal barrier function is urgently needed. RESULTS: Dietary polysaccharide deprivation induced intestinal barrier dysfunction, decreased growth performance, altered microbial composition (Faecalibacterium, Dorea, and Coprobacillus), and reduced isobutyrate concentration. The results showed that APS facilitates intestinal barrier function in broiler chickens, including a thicker mucus layer, reduced crypt depth, and the growth of tight junction proteins. We studied the landscape of APS-induced gut microbiota and found that APS selectively promoted the growth of Parabacteroides, a commensal bacterium that plays a predominant role in enhancing intestinal barrier function. An in vitro growth assay further verified that APS selectively increased the abundance of Parabacteroides distasonis and Bacteroides uniformis. Dietary APS supplementation increased the concentrations of isobutyrate and bile acid (mainly chenodeoxycholic acid and deoxycholate acid) and activated signaling pathways related to intestinal barrier function (such as protein processing in the endoplasmic reticulum, tight junctions, and adherens junction signaling pathways). CONCLUSIONS: APS intervention restored the dietary polysaccharide-induced dysfunction of the intestinal barrier by selectively promoting the abundance of Parabacteroides distasonis, and increasing the concentrations of isobutyrate and bile acids (mainly CDCA and DCA). These findings suggest that APS-induced gut microbiota and metabolic niches are promising strategies for enhancing intestinal barrier function.