To address the life span of materials in the process of daily use, new types of structural nanofibers, fabricated by multifluid electrospinning to encapsulate both epoxy resin and amine curing agent, were embedded into an epoxy matrix to provide it with self-healing ability. The nanofibers, which have a polyacrylonitrile sheath holding two separate cores, had an average diameter of 300 ± 140 nm with a uniform size distribution. The prepared fibers had a linear morphology with a clear three-chamber inner structure, as verified by scanning electron microscope and transmission electron microscope images. The two core sections were composed of epoxy and amine curing agents, respectively, as demonstrated under the synergistic characterization of Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), and differential scanning calorimetry. The TGA results disclosed that the core-shell nanofibers contained 9.06% triethylenetetramine and 20.71% cured epoxy. In the electrochemical corrosion experiment, self-healing coatings exhibited an effective anti-corrosion effect, unlike the composite without nanofibers. This complex nanostructure was proven to be an effective nanoreactor, which is useful to encapsulate reactive fluids. This engineering process by multiple-fluid electrospinning is the first time to prove that this special multiple-chamber structure has great potential in the field of self-healing.

The presence of the roof structure affects airflow patterns around the building. The recirculation area formed in the roof area is different from the original due to the presence of parapets and billboards. So the traditional formula no longer applies. Pollutant gases emitted by buildings can accumulate in recirculation areas, causing air short circuits and polluting indoor air. However, studies on the flow characteristics of building roofs with parapets are still lacking. In this paper, cfd simulation is used to study the influence of parapets of different heights and summer thermal effects on airflow. The results show that as the height of the parapet increases, the size of the vortex generated at the top also increases gradually. As the temperature difference between the top and the air increases, that is, the Ri increases, the vortices formed on the top will decrease significantly and the amount of reduction is not linear with the temperature difference.