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Lab Develops First-Ever Living 3D-Printed Aneurysm
Ruptured brain aneurysm affect about 30,000 Americans each year and can lead to serious medical emergencies, including stroke, brain damage, and even death. Existing treatment options are limited, often invasive, and surgical outcomes vary. But clinicians may be able to improve existing treatment, thanks to researchers at Lawrence Livermore and their collaborators at Duke University and Texas A&M who produced the first-ever living, bio-printed aneurysm. Their work appeared in the October 16, 2020, edition of Biofabrication.
The team, led by engineers William “Rick” Hynes and Monica Moya, were able to replicate an aneurysm in vitro by 3D printing blood vessels with human cerebral cells. Hynes then performed an endovascular repair procedure on the printed aneurysm, introduced blood plasma, and observed the formation of a blood clot. The researchers then documented the “post-op” healing process of the endothelial cells within the vessels.
“We thought that if we could pair computational modeling and experimental approaches, maybe we could come up with a method for selecting personalized treatment,” says Hynes, “Now we can start to build the framework of a model that surgical practitioners can use to determine best practices for treating aneurysms.” In addition to patient-specific care and serving as a testbed for surgical training, researchers say the platform will enhance understanding of basic biology and the post-surgery healing response.
Contact: Rick Hynes (925) 423-5465 (hynes2@llnl.gov).
100-Year-Old Metallurgy Puzzle Solved
For millennia, humans have exploited how metals become stronger when physically deformed or hardened. The root cause of metal hardening remained a mystery until 87 years ago, when it was first proposed that dislocations—curvilinear crystal defects made of lattice disorder—are responsible for crystal plasticity. Despite the establishment of the direct, causal connection between dislocations and crystal plasticity, no one had observed what dislocations actually do while the crystal is deformed. To solve this mystery, a team from Lawrence Livermore, led by materials scientist Vasily Bulatov, performed atomistic simulations at the limits of supercomputing capability to observe atomic-level mechanisms of metal hardening. The simulations were performed on Livermore’s Vulcan and Lassen supercomputers and Mira supercomputer at Argonne National Laboratory. Their work appeared in the October 5, 2020, edition of Nature Materials.
The team demonstrated that the “notorious” staged (slow–fast–slow) hardening of single-crystalline metals is a direct consequence of crystal rotation under uniaxial straining. At odds with divergent and contradictory analyses in the literature, the Livermore researchers found that the basic mechanisms of dislocation behavior are the same across all three stages of metal hardening. “In our simulations we saw exactly how the motion of individual atoms translates into the motion of dislocations that conspire to produce metal hardening,” says Bulatov.
Other Livermore scientists included Luis Zepeda-Ruiz, Tomas Oppelstrup, Nicolas Bertin, and Nathan Barton. Alexander Stukowski (a former Livermore postdoc) from Technische Universität Darmstadt Germany, and Rodrigo Freitas of the University of California, Berkeley and Stanford University also contributed to this work.
Contact: Vasily Bulatov (925) 423-0124 (bulatov1@llnl.gov).
Seafloor Gases Illuminated
Methane hydrate, a naturally occurring crystalline solid that forms from hydrocarbon gases (commonly methane) and water in the seafloor and continental shelves, is a source of natural gas, as well as a potential contributor to ocean acidification and climate change. Its presence lowers the electrical conductivity of the seafloor, in comparison to hydrate-free formations, allowing the gases to be imaged by geophysical methods. Measurement of seafloor electrical conductivity, either using borehole logs or geophysical prospecting methods, is one of the most reliable ways for estimating hydrate location and abundance, but these methods must be calibrated using laboratory measurements of hydrate-sediment mixtures.
To provide this essential data, Lawrence Livermore scientists and their collaborators at the U.S. Geological Survey and Scripps Institution of Oceanography at University of California, San Diego synthesized methane hydrate in mixtures with sediments in the laboratory to determine their electrical conductivity. Their findings were published in the August 4, 2020, issue of Geophysical Research Letters.
Current estimates suggest there are substantially higher amounts of natural gas associated with gas hydrates than all the continental shale reservoirs combined. “Determining the global distribution and inventory of petrogenic organic carbon in the crust is important to gaining a basic understanding of the Earth’s deep carbon cycle,” says Wyatt Du Frane, a Livermore materials scientist and contributing author. “Our lab results are consistent with wellbore core samples obtained in the field that show high concentrations of gas hydrate. This gives geophysicists a validated target for locating and mapping distributions of this type of gas hydrate formation in the seafloor.”
Contact: Wyatt Du Frane (925) 423-8026 (dufrane2@llnl.gov).
