The viscoelastic surfactant (VES) fracturing fl uid is new fracturing system, which is primarily made up of viscoelastic surfactant and some other auxiliaries. The traditional VES fracturing fl uid has the obvious advantages in gel breaking, fl owing back, carrying sands, etc. However, they are centered largely in the aspects of medium and low temperature system. In this paper, the work is focus on the need for the VES fracturing fl uid with high temperature resistance. In the experiment, four kinds of viscoelastic surfactants with hydroxyl were fi rstly synthesized, which were named C 14 -1, C 16 -1, C 14 -2 and C 16 -2 respectively. Then the formulation of VES fracturing fl uid was determined in accordance with the apparent viscosity of solution, and the formulation was that concentration of C 16 -2 and NaSal were 2.5% and 1% respectively. It was found that the VES fracturing fl uid has excellent effectiveness via testing properties of temperature resistance, shear stability, sand-carrying and gel breaking. When the temperature of system was 144°C, the apparent viscosity of the VES fracturing fl uid was 25 mPa s, which could demand the requirements of carrying sands as well as support agents, and it could resist high temperature well. It is also observed that the VES fracturing fl uid is the pseudoplastic fl uid, which contributes to getting the cracks with excellent negotiability.
Intestinal stem cells (ISCs) are essential to maintain intestinal epithelial regeneration and barrier function. Our previous work showed that glucomannan from Aloe vera gel (AGP) alleviated epithelial damage, but the mechanism was still elusive. Herein, RNA-sequencing analysis showed that proliferation and differentiation of intestinal epithelial cells as well as the canonical Wnt pathway were involved in this process. Further experiments exhibited that AGP promoted nuclear translocation of β-catenin and expression of transcription factor 7, increased the number of Lgr5 + ISCs, and differentiated epithelial cells in mice colon. Intriguingly, AGP reversed the inhibition of IEC-6 cells proliferation induced by an inhibitor of the canonical Wnt pathway. Hence, this study implied that AGP promoted proliferation and differentiation of colon stem cells via Wnt/β-catenin signaling, which subsequently facilitated the regeneration of epithelial cells and alleviated colitis in mice. It may provide new insights into the role of polysaccharides in regulating intestinal homeostasis and relieving intestinal injury.
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