May 29, 2020
These swabs, representing a number of designs generated by the Covidswab Github collaboration, were 3D-printed at LLNL from a biocompatible, surgical-grade resin and tested in the Advanced Manufacturing Laboratory.
Swab shortage relief
In this era of COVID-19, tracking the disease adequately enough to allow state and local officials to lift shelter-in-place orders and return to a semblance of normalcy in the absence of a vaccine will require widespread testing, according to medical experts.
However, such extensive testing efforts have been hampered due to a shortage of nasopharyngeal (NP) swabs, the preferred tool used by clinicians to collect samples for COVID diagnoses.
To address the problem, Lawrence Livermore National Laboratory engineers formed an ad hoc, rapid response team that has tested more than a dozen novel, 3D-printed nasal swab designs (hundreds of individual swabs) from a grassroots coalition of commercial and academic partners.
The mechanical tests performed at the Lab, simulating how the swabs might be used in a clinical environment, provided valuable feedback that improved the designs, enabling them to meet requirements for COVID-19 testing
A carbon nanotube porin embedded in a lipid bilayer with an anion (green) at the entrance of the carbon nanotube porin. The anion is fully hydrated, i.e. surrounded by bound water molecules, which it needs to shed before entering the nanotube. A window in the nanotube (below) shows another anion that shed some of those water molecules and entered the tube interior. Image by Zhongwu Li, Fikret Aydin, Tuan Anh Pham and Alex Noy/LLNL.
Membrane transport gets picky
Trying to determine how negatively charged ions squeeze through a carbon nanotube 20,000 times smaller than a human hair is no easy feat.
Not only did Lawrence Livermore National Laboratory scientists do that but they found that those ions are unexpectedly picky depending on the anion (a negatively charged ion).
Inner pores of carbon nanotubes combine extremely fast water transport and ion selectivity that could potentially be useful for high-performance water desalination and separation applications. Determining which anions are permeable to the nanotube pore can be critical to many separation processes, including desalination, which turns seawater into fresh water by removing the salt ions.
Inner and outer view of an N95 mask between dry heat treatment cycles showing no deformation of the respirator. A thermocouple is affixed to the inner surface of the respirator with Kapton tape to measure the surface temperature of the mask over 10 heating cycles in a standard laboratory convection box oven. Masks are heat treated inside a self-sealing autoclave pouch (background) to prevent dispersion of viral particles from airflow inside the oven. Photos by Trevis Massey/LLNL.
Wear, wash, reuse
Lawrence Livermore National Laboratory (LLNL) is studying ways to safely and rapidly remove viral threats from N95 respirators without compromising the device’s fit and its ability to filter particles so they can be reused.
N95 masks typically are used once in health care settings because they can be contaminated when treating infected patients, posing a risk to caregivers who continue wearing them as well as to other patients treated by the provider. The pandemic has resulted in N95 shortages.
Interdisciplinary LLNL researchers including materials scientists, biologists and engineers are exploring ways to deactivate the SARS-CoV-2 virus on N95 respirators by using inexpensive tools that are readily available in hospitals and field settings to ensure their continued availability.
The smart protection mechanism of responsive nanotube membranes against environmental threats. The collapse of actuating polymer chains on the contaminated membrane surface prevents nerve agents like sarin from entering the SWCNT pores. In a safe environment, the responsive polymer chains remain extended and allow rapid transport of water vapor, thus conferring high breathability to the membrane material. Image by Ryan Chen/LLNL.
Don’t sweat it: You’re protected
A Lawrence Livermore National Laboratory-led team of scientists has developed a breathable, protective smart fabric — deemed a “second skin” — that is designed to shield wearers by responding to chemical and biological agents.
Researchers from the Lab and collaborators from the Massachusetts Institute of Technology and U.S. Army Combat Capabilities Development Command recently completed the first phase of a project to create the new material, which can autonomously react to microscopic dangers in its environment and might offer a glimpse into the future of smart uniforms worn by the military and first responders.
“Combining breathability and protection in the same garment is very challenging, but key for their safe, extended use,” said Francesco Fornasiero, the LLNL scientist who led the team.
Standard protective fabrics that protect against biological and chemical agents typically inhibit breathability, but that’s where the second skin is different. It provides robust protection against the agents but also offers wearers a level of comfort akin to being in their own skin.
All-atom modeling reveals that TATB explosives form highly reactive shear bands of disordered material when shocked to detonation conditions, pointing to a previously unaccounted for ignition source.
It’s a blast
Two Lawrence Livermore National Laboratory scientists have discovered a new mechanism for ignition of high explosives that explains the unusual detonation properties of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).
The research will allow for systematic improvements to continuum mechanics models used to assess the performance and safety of the material accurately and reliably.
Highly insensitive explosives offer greatly enhanced safety properties over more conventional explosives, but the physical properties responsible for the safety characteristics are not clear. Among explosives, TATB is nearly unique in its safety-energy trade-offs.
The team used supercomputer simulations involving many millions of atoms to peek at the material response right behind a detonation shock wave. What they found was the dynamic formation of a complicated network of shear bands in the material. Shear bands are local regions of highly disordered material that are produced when the material fails under extreme stresses.
