Composite biopolymer/conducting polymer scaffolds, such as polylactic acid (PLA)/ polyaniline (PAni) nanofibers, have emerged as popular alternative scaffolds in the electrical-sensitive nerve tissue engineering (TE). Although mimicking the extracellular matrix geometry, such scaffolds are highly hydrophobic and usually present an inhomogeneous morphology with massive beads that impede nerve cell-material interactions. Therefore, the present study launches an exclusive combinatorial strategy merging successive pre- and post-electrospinning plasma treatments to cope with these issues. Firstly, an atmospheric pressure plasma jet (APPJ) treatment was applied on PLA and PLA/PAni solutions prior to electrospinning, enhancing their viscosity and conductivity. These liquid property changes largely eliminated the beaded structures on the nanofibers, leading to uniform and nicely elongated fibers having average diameters between 170 and 230 nm. After electrospinning, the conceived scaffolds were subjected to a N₂ dielectric barrier discharge (DBD) treatment, which significantly increased their surface wettability as illustrated by large decreases in water contact angles for values above 125° to values below 25°. X-ray photoelectron spectroscopy (XPS) analyses revealed that 3.3% of nitrogen was implanted on the nanofibers surface in the form of C–N and N–C=O functionalities upon DBD treatment. Finally, after seeding pheochromocytoma (PC-12) cells on the scaffolds, a greatly enhanced cell adhesion and a more dispersive cell distribution were detected on the DBD-treated samples. Interestingly, when the APPJ treatment was additionally performed, the extension of a high number of long neurites was spotted leading to the formation of a neuronal network between PC-12 cell clusters. In addition, the presence of conducting PAni in the scaffolds further promoted the behavior of PC-12 cells as illustrated by more than a 40% increase in the neurite density without any external electrical stimulation. As such, this work presents a new strategy combining different plasma-assisted biofabrication techniques of conducting nanofibers to create promising scaffolds for electrical-sensitive TE applications.

One-side welding with back formation technique is widely used in pressure vessels and the pressure piping industry. Welders provide high importance to the role of the fusion hole in this type of welding. Therefore, the formation and instability of the fusion hole should be studied to realize the welding automation of the one-side welding with back formation process. A visual sensing system is established to capture the image of the fusion hole, and the behavior of the fusion hole is investigated. Results show that the typical process of the fusion hole includes formation, growth, and macro quasi steady state. The welding parameter scoop to obtain the stable fusion hole is narrow. After deviating from the appropriate parameter scoop, the fusion hole will enter unstable states, thereby resulting in the “fusion hole effect” failure of the welding process. Depending on the change in the shape of the fusion hole, instability types of the fusion hole can be divided into longitudinal, lateral, and gradual shrinking instability. Different instability types correspond to different changing laws of fusion hole morphology. The instability characteristics of the fusion hole can provide effective early warning information prior to the “fusion hole effect” failure.