Uniformity evaluation and improvement technology of sandy clayey purple soil enhanced through microbially-induced calcite precipitation

In order to improve the uniformity of calcite precipitation and engineering practicability,a series of tests using bacillus megaterium(BNCC 336739)were conducted to enhance sandy clayey purple soil,with different concentration bacterial solution and cementation reagent flowing to the samples perforated in the center with different grouting speed.Based on the mineral component(XRD)and soil microstructure(SEM),cementation mechanism was analyzed.Based on measurement of CaCO3 production and unconfined compressive strength tests,the influence law of grouting factors on CaCO3 production amount(C),CaCO3 uniformity(s),CaCO3 deposition rate(P),unconfined compressive strength(UCS)and stiffness(elastic secant modulus E50)were analyzed and the correlation between C,s and UCS,E50 were analyzed.The results show that the uniformity can be improved by perforation grouting,and the UCS and E50 of samples treated by MICP increased by 105.58%and 464.14%.The CaCO3 induced by bacillus megaterium are 1-5μm calcite crystal,which cemented and wrapped soil particles.The higher the concentration of bacteria solution and cementation reagent and the slower the grouting speed are,the bigger the C and the s.The C has a lower threshold of 2.5%and an upper threshold of 5%,the UCS of samples treated by MICP significantly increases with the increase of C in the interval,and the UCS growth becomes slow or even negative outside the interval.The smaller the s is,the bigger the UCS and E50 are,and this effect is small when C<4%and is significant when C>4%.With the effect of s,the UCS and E50 of sample treated by MICP increase with different speed and then reduced as the increase of C.It provides scientific reference for the application of MICP technology in purple soil area.

Nuciferine protects against high-fat diet-induced hepatic steatosis and insulin resistance via activating TFEB-mediated autophagy——lysosomal pathway

Nonalcoholic fatty liver disease(NAFLD) is characterized by hepatic steatosis and insulin resistance and there are currently no approved drugs for its treatment.Hyperactivation of mTOR complex1(mTORCl) and subsequent impairment of the transcription factor EB(TFEB)-mediated autophagy-lysosomal pathway(ALP) are implicated in the development of NAFLD.Accordingly,agents that augment hepatic TFEB transcriptional activity may have therapeutic potential against NAFLD.The objective of this study was to investigate the effects of nuciferine,a major active component from lotus leaf,on NAFLD and its underlying mechanism of action.Here we show that nuciferine activated ALP and alleviated steatosis,insulin resistance in the livers of NAFLD mice and palmitic acid-challenged hepatocytes in a TFEB-dependent manner.Mechanistic investigation revealed that nuciferine interacts with the Ragulator subunit hepatitis B X-interacting protein and impairs the interaction of the Ragulator complex with Rag GTPases,thereby suppressing lysosomal localization and activity of mTORC1,which activates TFEB-mediated ALP and further ameliorates hepatic steatosis and insulin resistance.Our present results indicate that nuciferine may be a potential agent for treating NAFLD and that regulation of the mTORCl-TFEB-ALP axis could represent a novel pharmacological strategy to combat NAFLD.