为研究丁酸梭菌的益生特性及其胞外代谢产物,通过体外模拟试验评估其益生特性,包括对模拟消化道、胆盐耐受性、疏水性和自聚集性,以及发酵液的抑菌活性,并采用超高效液相色谱-四极杆静电场轨道阱质谱(ultra-high performance liquid chr...为研究丁酸梭菌的益生特性及其胞外代谢产物,通过体外模拟试验评估其益生特性,包括对模拟消化道、胆盐耐受性、疏水性和自聚集性,以及发酵液的抑菌活性,并采用超高效液相色谱-四极杆静电场轨道阱质谱(ultra-high performance liquid chromatography and four-stage pole electrostatic field orbital trap mass spectrometry,UHPLC-QE-MS)技术对其胞外代谢产物进行非靶向代谢组学分析。结果表明,丁酸梭菌对模拟消化道环境和胆盐具有较强的耐受性,经模拟消化道环境处理2.5 h,其存活率仍高达90%以上,可耐受浓度低于0.4%的胆盐;其疏水率与12 h的自聚集率均在30%以上;其发酵上清液对福氏志贺氏菌有显著抑菌作用(P<0.05),对大肠埃希氏菌、鼠伤寒沙门氏菌、单核细胞增生李斯特菌有一定抑菌作用,对金黄色葡萄球菌无抑菌作用。丁酸梭菌胞外代谢产物主要有12种有机酸类、7种氨基酸类、5种核苷类和7种其他物质,部分活性代谢物具有一定的益生作用和应用于食品生产的潜力。展开更多
Carbon nanotubes(CNTs) have shown as unique nanoreactors to tune the catalytic activity of confined nano-catalysts. Here we report that the catalytic performance of molybdenum carbide nanoparticles(MoC_x NPs) for the ...Carbon nanotubes(CNTs) have shown as unique nanoreactors to tune the catalytic activity of confined nano-catalysts. Here we report that the catalytic performance of molybdenum carbide nanoparticles(MoC_x NPs) for the hydrogen evolution reaction(HER) process can be enhanced by encapsulation within single-walled carbon nanotubes(SWNTs) with a diameter of 1–2 nm. The catalyst with MoC_x NPs located on the interior surface of SWNTs(MoCx@SWNTs) exhibits a lower onset over-potential and a smaller Tafel slope than the one with MoC_x NPs attached on the exterior surface(MoCx/SWNTs). This is likely attributed to the much smaller particle size and the more reduced states of the confined MoC_x NPs, as well as the larger specific surface area of MoCx@SWNTs compared with Mo Cx/SWNTs. In addition, the electronic structure of the confined MoC_x NPs might be modified by the confinement effects of SWNTs, and hence the adsorption free energy of H atoms on the confined MoC_x NPs, which could also contribute to their higher performance. These results suggest that the SWNTs can be further explored for constructing novel catalysts with beneficial catalytic performance.展开更多
The effect of the Al2O3 structure on the performance of Pt/Ga/Al2O3 catalysts is investigated for the direct dehydrogenation of propane. The study unveils that the structure of Al3+determines the bulk structure of cat...The effect of the Al2O3 structure on the performance of Pt/Ga/Al2O3 catalysts is investigated for the direct dehydrogenation of propane. The study unveils that the structure of Al3+determines the bulk structure of catalysts, particularly a high content of coordinatively unsaturated Al3+sites(penta-coordinated Al3+,denoted as Al3+penta) could lead to a remarkably improved dehydrogenation activity of the catalyst. The bulk characterization reveals that the sufficient amount of Al3+pentain Al2O3 benefit the dispersion of Pt and Ga2O3 on the Al2O3 support. At the same time, TPR results reveal that the presence of Pt facilitates the reduction of Ga2O3, likely due to the hydrogen spillover between the well dispersed Pt and Ga2O3,which consequently enhances the synergistic function between Pt and Ga2O3 in the dehydrogenation of propane. Recyclability tests demonstrate that the dehydrogenation activity stabilizes after three cycles over the Pt/Ga/Al2O3 catalyst.展开更多
Boron had been introduced into the structure of carbon material(BC), which was used as the support of Pd catalyst for hydrogenation of 4-carboxybenzaldehyde(4-CBA). The physical properties and chemical composition of ...Boron had been introduced into the structure of carbon material(BC), which was used as the support of Pd catalyst for hydrogenation of 4-carboxybenzaldehyde(4-CBA). The physical properties and chemical composition of the support and corresponding catalyst were characterized by N2 adsorption–desorption,Raman spectroscopy, inductively coupled plasma optical emission spectroscopy(ICP-OES), element analysis(EA), high-resolution transmission electron microscopy(HRTEM), CO-pulse chemisorption and X-ray photoelectron spectroscopy(XPS). The results demonstrate that Pd/BC catalyst exhibits a superior activity and good stability due to the more uniform dispersion of Pd nanoparticles, the presence of mesoporous structure and the enhanced interaction between Pd nanoparticles and the support, compared to carbon and N-doped carbon supported Pd catalysts(Pd/C and Pd/NC, respectively).展开更多
文摘为研究丁酸梭菌的益生特性及其胞外代谢产物,通过体外模拟试验评估其益生特性,包括对模拟消化道、胆盐耐受性、疏水性和自聚集性,以及发酵液的抑菌活性,并采用超高效液相色谱-四极杆静电场轨道阱质谱(ultra-high performance liquid chromatography and four-stage pole electrostatic field orbital trap mass spectrometry,UHPLC-QE-MS)技术对其胞外代谢产物进行非靶向代谢组学分析。结果表明,丁酸梭菌对模拟消化道环境和胆盐具有较强的耐受性,经模拟消化道环境处理2.5 h,其存活率仍高达90%以上,可耐受浓度低于0.4%的胆盐;其疏水率与12 h的自聚集率均在30%以上;其发酵上清液对福氏志贺氏菌有显著抑菌作用(P<0.05),对大肠埃希氏菌、鼠伤寒沙门氏菌、单核细胞增生李斯特菌有一定抑菌作用,对金黄色葡萄球菌无抑菌作用。丁酸梭菌胞外代谢产物主要有12种有机酸类、7种氨基酸类、5种核苷类和7种其他物质,部分活性代谢物具有一定的益生作用和应用于食品生产的潜力。
基金financially supported by the National Natural Science Foundation of China (No. 21425312, 21688102, 21621063, and 21573224)
文摘Carbon nanotubes(CNTs) have shown as unique nanoreactors to tune the catalytic activity of confined nano-catalysts. Here we report that the catalytic performance of molybdenum carbide nanoparticles(MoC_x NPs) for the hydrogen evolution reaction(HER) process can be enhanced by encapsulation within single-walled carbon nanotubes(SWNTs) with a diameter of 1–2 nm. The catalyst with MoC_x NPs located on the interior surface of SWNTs(MoCx@SWNTs) exhibits a lower onset over-potential and a smaller Tafel slope than the one with MoC_x NPs attached on the exterior surface(MoCx/SWNTs). This is likely attributed to the much smaller particle size and the more reduced states of the confined MoC_x NPs, as well as the larger specific surface area of MoCx@SWNTs compared with Mo Cx/SWNTs. In addition, the electronic structure of the confined MoC_x NPs might be modified by the confinement effects of SWNTs, and hence the adsorption free energy of H atoms on the confined MoC_x NPs, which could also contribute to their higher performance. These results suggest that the SWNTs can be further explored for constructing novel catalysts with beneficial catalytic performance.
基金the National Natural Science Foundation of China(No.21676195)the China Postdoctoral Science Foundation(2016M601347)。
文摘The effect of the Al2O3 structure on the performance of Pt/Ga/Al2O3 catalysts is investigated for the direct dehydrogenation of propane. The study unveils that the structure of Al3+determines the bulk structure of catalysts, particularly a high content of coordinatively unsaturated Al3+sites(penta-coordinated Al3+,denoted as Al3+penta) could lead to a remarkably improved dehydrogenation activity of the catalyst. The bulk characterization reveals that the sufficient amount of Al3+pentain Al2O3 benefit the dispersion of Pt and Ga2O3 on the Al2O3 support. At the same time, TPR results reveal that the presence of Pt facilitates the reduction of Ga2O3, likely due to the hydrogen spillover between the well dispersed Pt and Ga2O3,which consequently enhances the synergistic function between Pt and Ga2O3 in the dehydrogenation of propane. Recyclability tests demonstrate that the dehydrogenation activity stabilizes after three cycles over the Pt/Ga/Al2O3 catalyst.
基金supported by the National Natural Science Foundation of China (No. 21425312 and 21321002)
文摘Boron had been introduced into the structure of carbon material(BC), which was used as the support of Pd catalyst for hydrogenation of 4-carboxybenzaldehyde(4-CBA). The physical properties and chemical composition of the support and corresponding catalyst were characterized by N2 adsorption–desorption,Raman spectroscopy, inductively coupled plasma optical emission spectroscopy(ICP-OES), element analysis(EA), high-resolution transmission electron microscopy(HRTEM), CO-pulse chemisorption and X-ray photoelectron spectroscopy(XPS). The results demonstrate that Pd/BC catalyst exhibits a superior activity and good stability due to the more uniform dispersion of Pd nanoparticles, the presence of mesoporous structure and the enhanced interaction between Pd nanoparticles and the support, compared to carbon and N-doped carbon supported Pd catalysts(Pd/C and Pd/NC, respectively).
