Improving UV Resistance of Aramid Fibers by Simultaneously Synthesizing TiO2 on Their Surfaces and in the Interfaces Between Fibrils/Microfibrils Using Supercritical Carbon Dioxide

Aramid fibers with low density and high strength, modulus, and thermal resistance are widely used in applications such as bulletproof vests and cables. However, owing to their chemical structure, they are sensitive to ultraviolet light, which degrades the fibers’ useful mechanical properties. In this study, titanium dioxide (TiO2) nanoparticles were synthesized both on the aramid III fiber surface and in the interfacial space between the fibrils/microfibrils in supercritical carbon dioxide (scCO2) to improve the UV resistance of aramid fibers. The effects of scCO2 treatment pressure on the TiO2 structure, morphology, surface composition, thermal stability, photostability, and mechanical properties were investigated using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, ultraviolet–visible spectroscopy, and single-fiber test. The results show that amorphous TiO2 formed on the fiber surface and the interface between fibrils/microfibrils, and decreased the photodegradation rate of the aramid III fiber. Moreover, this modification can also improve the tensile strength via treatment at low temperature and without the use of a solvent. The simple synthesis process in scCO2, which is scalable, is used for mild modifications with a green solvent, providing a promising technique for synthesizing metal dioxide on polymers

Gut Microbiota and Relevant Metabolites Analysis in Alcohol Dependent Mice

Alcohol abuse is a major public health crisis. Relative evidences supported that the gut microbiota (GM) played an important role in central nervous system (CNS) function, and the composition of them had changed after alcohol drinking. We sought to explore the changes of GM in alcohol dependence. In our study, the GM of mice with alcohol administration was detected through analyzed 16S rRNA gene sequencing and the fecal metabolites were analyzed by LC-MS. The microbial diversity was significantly higher in the alcohol administration group, the abundance of phylum Firmicutes and its class Clostridiales were elevated, meanwhile the abundance of Lachnospiraceae, Alistipes, and Odoribacter showed significant differences among the three groups. Based on LC-MS results, bile acid, secondary bile acid, serotonin and taurine level had varying degrees of changes in alcohol model. From paraffin sections, tissue damage was observed in liver and colon. These findings provide direct evidence that alcohol intake affects the composition of GM, enable a better understanding of the function of GM in the microbiota-gut-brain (MGB) axis, and give a new thought for alcohol addiction treatment