Gut microbiota dynamics and fecal SCFAs after colonoscopy: accelerating microbiome stabilization by Clostridium butyricum.

BACKGROUND: Colonoscopy is a classic diagnostic method with possible complications including abdominal pain and diarrhoea. In this study, gut microbiota dynamics and related metabolic products during and after colonoscopy were explored to accelerate gut microbiome balance through probiotics. METHODS: The gut microbiota and fecal short-chain fatty acids (SCFAs) were analyzed in four healthy subjects before and after colonoscopy, along with seven individuals supplemented with Clostridium butyricum. We employed 16S rRNA sequencing and GC-MS to investigate these changes. We also conducted bioinformatic analysis to explore the buk gene, encoding butyrate kinase, across C. butyricum strains from the human gut. RESULTS: The gut microbiota and fecal short-chain fatty acids (SCFAs) of four healthy subjects were recovered on the 7th day after colonoscopy. We found that Clostridium and other bacteria might have efficient butyric acid production through bioinformatic analysis of the buk and assessment of the transcriptional level of the buk. Supplementation of seven healthy subjects with Clostridium butyricum after colonoscopy resulted in a quicker recovery and stabilization of gut microbiota and fecal SCFAs on the third day. CONCLUSION: We suggest that supplementation of Clostridium butyricum after colonoscopy should be considered in future routine clinical practice.

Anti-Helicobacter pylori activity and gastroprotective effects of human stomach-derived Lactobacillus paragasseri strain LPG-9.

The eradication of Helicobacter pylori is an urgent global issue. However, the traditional regimens have several limitations. Thus, we propose the idea of treating bacterial gastric disease with the objective of eliminating gastric pathogenic bacteria and enhancing gastroprotective effects using gastric probiotics. In this study, a total of 12 Lactobacillus strains were isolated from the gastric mucosa of healthy donors. After evaluation using a weight scoring system, Lactobacillus paragasseri strain LPG-9 was identified as the most promising probiotic for gastric disease, with the highest acid-resistance and the best adhesion characteristics. Gastric colonisation, H. pylori inhibition, anti-inflammatory, and gastric homeostasis effects of LPG-9 were confirmed in C57BL/6 mice. Finally, a safety evaluation and whole-genome sequencing were performed. Based on the results of this study, LPG-9 originates from the gastric microbiota and is a promising probiotic for gastric disease, particularly H. pylori-induced gastritis, providing a solution to this global issue.

Structure and conductivity enhanced treble-shelled porous silicon as an anode for high-performance lithium-ion batteries.

Silicon is regarded as the next generation anode material for lithium-ion batteries because of its high specific capacity, low intercalation potential and abundant reserves. However, huge volume changes during the lithiation and delithiation processes and low electrical conductivity obstruct the practical applications of silicon anodes. In this study, a treble-shelled porous silicon (TS-P-Si) structure was synthesized via a three-step approach. The TS-P-Si anode delivered a capacity of 858.94 mA h g-1 and a capacity retention of 87.8% (753.99 mA h g-1) after being subjected to 400 cycles at a current density of 400 mA g-1. The good cycling performance was due to the unique structure of the inner silicon oxide layer, middle silver nano-particle layer and outer carbon layer, leading to a good conductivity and a decreased volume change of this silicon-based anode.

Ultra-small Rh nanoparticles supported on WO3-x nanowires as efficient catalysts for visible-light-enhanced hydrogen evolution from ammonia borane.

Hydrolysis of ammonia borane (AB) is a safe and convenient means of H2 production when efficient catalysts are used. Here we report a facile one-pot solvothermal method to synthesize Rh/WO3-x hybrid nanowires. Ultra-small Rh nanoparticles with an average size of ∼1.7 nm were tightly anchored on WO3-x nanowires. Rh/WO3-x catalysts exhibited substantially enhanced activity for hydrolytic dehydrogenation of AB under both dark and visible light irradiation conditions relative to mixed Rh nanoparticles and WO3-x nanowires (Rh + WO3-x ), and Rh/C and WO3-x nanowires. X-ray photoelectron spectroscopy (XPS) analysis indicated that the synergistic effect between Rh nanoparticles and WO3-x nanowires was responsible for such an enhancement in activity. Specifically, Rh/WO3-x achieved the highest turnover frequency (TOF) with a value of 805.0 molH2 molRh -1 min-1 at room temperature under visible light irradiation. The H2 release rate as a function of reaction time exhibited a volcano plot under visible light irradiation, indicating that a self-activation process occurred in the hydrolytic dehydrogenation of AB due to additional oxygen vacancies arising from in situ reduction of WO3-x nanowires by AB, and thus an enhanced localized surface plasmon resonance (LSPR). Such a self-activation process was responsible for the enhanced catalytic activity under visible light irradiation relative to that under dark conditions, which was supported by the lower activation energy (45.2 vs. 50.5 kJ mol-1). In addition, Rh/WO3-x catalysts were relatively stable with only little loss in activity after five cycles due to the tight attachment between two components.

In situ synthesis of carbon doped porous silicon nanocomposites as high-performance anodes for lithium-ion batteries.

We demonstrate the in situ synthesis of carbon doped porous silicon (Si/C) nanocomposites by a simple thermal displacement process between Mg2Si and inorganic gas CO2 in one-step. Via the decomposition of Mg2Si, the reduction process occurred between Mg and CO2, leading the uniform doping of many distributed tiny carbon nanoparticles into Si. Meanwhile, the porous structure was formed after an acid treatment. When worked as anodes for lithium-ion batteries, the as-prepared s-porous Si/C nanocomposites exhibited good cycling stability and high-rate capability, which were superior to the porous Si and porous Si/C nanocomposites. It was revealed that the enhanced electrochemical properties could be ascribed to the novel porous structure and doped carbon nanoparticles that can buffer the volume expansion, as well as enhance the electronic conductivity of Si. The reaction mechanism was well investigated by studying the influence of reaction temperature and raw Mg2Si particle size on the morphology and component of the porous Si/C nanocomposites.

Wet-chemical synthesized MCMB@Si@C microspheres for high-performance lithium-ion battery anodes.

MCMB@Si@C microspheres, in which silicon nanoparticles were closely connected with mesocarbon microbeads (MCMBs) through strong chemical bonds, were synthesized as high-performance Li-ion battery anodes for the first time. Furthermore, the different surface functional groups, as interconnecting species, and their effects on the anode performance were characterized in detail.

Carbon dioxide as a green carbon source for the synthesis of carbon cages encapsulating porous silicon as high performance lithium-ion battery anodes.

Si/C composite is one of the most promising candidate materials for next-generation lithium-ion battery anodes. Herein, we demonstrate the novel structure of carbon cages encapsulating porous Si synthesized by the reaction between magnesium silicide (Mg2Si) and carbon dioxide (CO2) and subsequent acid washing. Benefitting from the in situ deposition through magnesiothermic reduction of CO2, the carbon cage seals the inner Si completely and shows higher graphitization than that obtained from the decomposition of acetylene. After removing MgO, pores are created, which can accommodate the volume change of the Si anode during the charge/discharge process. As the anode material for lithium-ion batteries, the porous Si/C electrode shows a charge capacity of ∼1124 mA h g-1 after 100 cycles with 86.4% capacity retention at the current density of 0.4 A g-1. When the current density increases to 1.6 and 3.2 A g-1, the capacity can still be maintained at ∼860 and ∼460 mA h g-1, respectively. The prominent cycling and rate performance is contributed by the built-in space for Si expansion, static carbon cages that prevent penetration of electrolyte and stabilize the solid electrolyte interface (SEI) outside, and fast charge transport by the novel structure.

A critical SiOx layer on Si porous structures to construct highly-reversible anode materials for lithium-ion batteries.

A novel Si/SiOx porous structure with a SiOx coating layer of varying thicknesses was prepared via a simple annealing and acid washing process. When used as an anode material for lithium-ion batteries, the Si/SiOx porous structure with an ∼9 nm SiOx coating layer demonstrates significantly improved electrochemical performance with a high reversible discharge capacity of over 915 mA h g-1 after 500 long cycles at 1 A g-1. The lithiation mechanism of a SiOx layer of different thicknesses has also been investigated.