Dielectric Barrier Discharge Applicator for Heating Carbon Nanotube-Loaded Interfaces and Enhancing 3D-Printed Bond Strength.

Material extrusion (ME) 3D printing is a revolutionary technique for manufacturing thermoplastic parts; however, the printed parts typically suffer from poor interlayer bonding, which causes weak tensile strength in the build direction. Many methods have been proposed to address the mechanical deficiencies of 3D-printed parts, but most fall short of a production-ready solution. Here we report the use of a dielectric barrier discharge (DBD) plasma electrode mounted concentrically around the nozzle of an ME 3D printer for in situ welding of thermoplastic parts. This is the first report of a DBD being used as a non-contact means to induce Joule heating in resistive composite materials. The polymer welding process is accomplished by coupling the DBD with the carbon nanotube-loaded interfaces between the 3D-printed layers. The current passing through the part results in rapid resistive heating of the nanotubes and thermal welding of the interfaces. We show that parts printed with this method have isotropic strength and are equivalent to their injection-molded counterparts.

Plasma generated ozone and reactive oxygen species for point of use PPE decontamination system.

This paper reports a plasma reactive oxygen species (ROS) method for decontamination of PPE (N95 respirators and gowns) using a surface DBD source to meet the increased need of PPE due to the COVID-19 pandemic. A system is presented consisting of a mobile trailer (35 m3) along with several Dielectric barrier discharge sources installed for generating a plasma ROS level to achieve viral decontamination. The plasma ROS treated respirators were evaluated at the CDC NPPTL, and additional PPE specimens and material functionality testing were performed at Texas A&M. The effects of decontamination on the performance of respirators were tested using a modified version of the NIOSH Standard Test Procedure TEB-APR-STP-0059 to determine particulate filtration efficiency. The treated Prestige Ameritech and BYD brand N95 respirators show filtration efficiencies greater than 95% and maintain their integrity. The overall mechanical and functionality tests for plasma ROS treated PPE show no significant variations.

Analysis for stress environment in the alveolar sac model.

Better understanding of alveolar mechanics is very important in order to avoid lung injuries for patients undergoing mechanical ventilation for treatment of respiratory problems. The objective of this study was to investigate the alveolar mechanics for two different alveolar sac models, one based on actual geometry and the other an idealized spherical geometry using coupled fluid-solid computational analysis. Both the models were analyzed through coupled fluid-solid analysis to estimate the parameters such as pressures/velocities and displacements/stresses under mechanical ventilation conditions. The results obtained from the fluid analysis indicate that both the alveolar geometries give similar results for pressures and velocities. However, the results obtained from coupled fluid-solid analysis indicate that the actual alveolar geometry results in smaller displacements in comparison to a spherical alveolar model. This trend is also true for stress/strain between the two models. The results presented indicate that alveolar geometry greatly affects the pressure/velocities as well as displacements and stresses/strains.