RESUMEN
Chinese Jiang-flavor Baijiu is the most widely consumed liquor. Jiang-flavor Daqu, a fermentation starter, is important sources of key flavors of Jiang-flavor Baijiu. Some microbes play significant roles in flavor formation of Daqu. In order to clarify the microbial population that promotes the formation of Daqu flavor, we use high throughput sequencing technology combined with headspace solid-phase microextraction gas chromatography-mass spectrometry to investigate microbial population and volatile compounds in Jiang-flavor Daqu. In addition, the dynamic changes of physicochemical factors and enzyme activities in Jiang-flavor Daqu were investigated. Correlations between microbial population, volatile compounds, physicochemical factors, and enzyme activities of Jiang-flavor Daqu were disclosed by redundancy analysis and Spearman correlation analysis. A total of 66 volatile compounds were identified and 14 primary microorganisms were selected. Results showed that high temperature environment could promote the formation of acids, aldehydes and ketones, phenols, furans by affecting the growth of Monascus, Trichomonascus, Cutaneotrichosporon, Wallemia, Millerozyma, Nigrospora, Cladosporium, Bacillus, and Pediococcus in the early fermentation stage. While high nitrogen environment was more suitable for the growth of Virgibacillus and Kroppenstedtia, who could promote the formation of pyrazines in the late fermentation stage. PRACTICAL APPLICATIONS: This study has provided a scientific basis for the directed regulation of Daqu fermentation through physicochemical factors, developed scientific basis for artificially constructing Daqu microbial population and obtaining an easy-to-operate, reproducible fermentation system for Daqu production.
Asunto(s)
Aldehídos , Nitrógeno , Fermentación , Furanos , Cetonas , Fenoles , PirazinasRESUMEN
Lithiumsulfur batteries (LSBs) are gradually replacing conventional lithium-ion batteries (LIBs), credited to their high theoretical capacity, low cost, and non-toxicity. Nevertheless, the substantial capacity degradation caused by the polysulfide shuttling during charging and discharging has seriously hindered the commercialization of LSBs. Separator modification with functionalized carbon materials has been found to catalyze the breakdown of polysulfides, thereby improving the efficiency of LSBs. Herein, we synthesized Ni/Co-PBAs with KB structures to subsequently derive Ni/Co/KB composites by a carbonization process, which were later used as a modifier layer on the barrier in LSBs in order to effectively alleviate the shuttle problem. The capacity of the Ni/Co/KB composite decorated separator is found to be 1032 mAh/g at 0.5 C with a coulombic efficiency closer to 100%. In the long-term cycling capability evaluation, the initial cycle is approximately 802.9 mAh/g at 1 C, while capacity retention after 400 cycles is also 678.8 mAh/g, with a high-capacity retention rate of 84.5%. The potential of these composites as modifying materials for superior LSBs separators is verified by experimental and theoretical methods.
RESUMEN
Lithium-sulfur (Li-S) batteries have a high specific capacity of 1675 mAh g-1 and are considered to be a promising next-generation energy storage system. A sulfur host for loading Co4N nanoparticles into porous carbon has been designed as the cathode for high-performance Li-S batteries. The porous carbon successfully confines sulfur and Co4N in the pores, and the synergistic effect of physical and chemical adsorption can effectively inhibit the dissolution and diffusion of polysulfides. Besides, the Co4N nanoparticles can also catalyze the redox reaction kinetics. At a current density of 0.5 C, S@KJ-Co4N cathodes deliver a high specific discharge capacity of 958.3 mAh g-1 and retain at 784.0 mAh g-1 after 200 cycles, corresponding to a decay rate of 0.09% per cycle. It is believed that this work can provide a promising strategy for the design of many energy storage systems.