Mei Li,Fenfen Wang,Jing Wang,Rui Wang,Padraig Strappe,Bo Zheng,Zhongkai Zhou,Ling Chen
High amylose maize starch (HAMS) and waxy maize starch (WMS) were modified by propionylation and their corresponding physicochemical characteristics, digestion and fermentation properties were studied. The results indicated that two new peaks related to methylene (2.20 ppm) and methyl (0.97 ppm) in the NMR spectrum were formed, indicating the occurrence of propionylation, and this was further confirmed by the formation of a characteristic absorption at 1747 cm −1 in the FTIR spectrum. The propionylation led the modified starch having a lower electron density contrast between the crystalline and amorphous flakes, resulting in the formation of a more compact structure following the increased degrees of substitution (DS). The propionylated starch also had a higher thermal stability and hydrophobicity . These structural changes increased the content of resistant starch (RS) and reduced the predicted glycemic index . More importantly, the gut microbiota fermentation properties indicated that the propionylation of the starch can not only increase the yield of propionate , but also increase the concentration of total short-chain fatty acids (SCFAs). This study highlights a new approach to significantly enhance the RS content in starch, together with an increased SCFA generation capacity.
Xueping Jiang,Hao Li,Jia Kong,Yuqi li,Xiangdong Xin,Jielin Zhou,Ran Zhang,Kwang Sik Lee,Byung Rae Jin,Zhongzheng Gui
Microbial degradation of chloramphenicol (CAP) has become important for reducing the adverse impact of environmental pollution with antibiotics. Although several pathways for CAP degradation have been identified in various bacteria, multiple metabolic pathways and their respective intermediate metabolites within a single strain are rarely reported. Here, Raoultella ornithinolytica CT3 was first isolated from silkworm excrement using CAP as the sole carbon source, and 100 mg/L CAP was almost completely degraded within 48 h. The biodegradation type of CAP followed first-order kinetics. Twenty-two CAP biotransformation products were identified using high-performance liquid chromatography and ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry. The CAP biotransformation pathways were predicted mainly in the acetylation and auxiliary pathways of propionylation and butyrylation. The toxicity of CAP biotransformation products was evaluated using the ecological structure-activity relationship (ECOSAR) model and biological indicators. The results showed that the toxicity of the intermediate metabolites changed slightly, but the final metabolite was harmless to the environment. Genomic analysis predicted that genes encoding acetyltransferase, amido-linkage hydrolase, nitroreductase, haloacetate dehalogenase, and protocatechuate 3,4-dioxygenase were associated with CAP biodegradation. This study provides new insights into the microbial degradation pathway of CAP and constitutes an ecological safety assessment for CAP-contaminated environments.
Zhenghao Li,Wei Wang,Xinmiao Liang,Jianlin Wang,Yonglin Xu,Wei Li
It is well established that paper-based separators display short-circuit risk in lithium-ion batteries due to their intrinsic micron-sized pores. In this research, we have adjusted pore structure of paper by fiber swelling in liquid electrolyte. Specifically, the paper-based separator is prepared by propionylated sisal fibers through a wet papermaking process. Scanning electron microscope (SEM) and multi-range X-ray nano-computed tomography (CT) images display strong swelling of modified fibers after electrolyte absorption, which can effectively decrease the pore size of separator. Due to the high electrolyte uptake (817 wt%), paper-based separator exhibits ionic conductivity of 2.93 mS cm −1 . 7 Li solid-state NMR spectroscopy and Gaussian simulation reveal that the formation of local high Li + ion concentration in the separator and its low absorption energy with Li + ion (62.2 kcal mol −1 ) is conducive to the ionic transportation. In particular, the assembled Li/separator/LiFePO 4 cell displays wide electrochemical stability window (5.2 V) and excellent cycle performance (capacity retention of 96.6% after 100 cycles at 0.5 C) due to the reduced side reactions as well as enhanced electrolyte absorption and retention capacity by propionylation. Our proposed strategy will provide a novel perspective to design high-performance bio-based separators to boost the development of clean and sustainable energy economy.
危险品化学品经营许可证（带存储）