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Sample Configuration for Ultrahigh Pressure Experiments
Livermore’s development of the toroidal diamond anvil cell has been revolutionary in pushing the static pressure limit in condensed-matter sciences. However, sample fabrication is nontrivial for very small anvils, and no standardized methods have been in place for such complex experiments. A global team, including researchers at Lawrence Livermore and Argonne national laboratories and Deutsches Elektronen-Synchrotron, have developed a new sample configuration that enables more reliable equation-of-state measurements in a pressure regime not previously achievable in diamond anvil cell experiments. Their results are published as an Editor’s Pick in the August 21, 2024, issue of the Journal of Applied Physics.
The team used the toroidal diamond anvil cell with a sample chamber diameter of approximately six micrometers. In this small sample chamber, the researchers microfabricated a sample package in a 10-step process whereby the target material is embedded in a uniform capsule of soft metal, which serves as a pressure-transmitting medium. This compression environment, in turn, improved the quality of equation-of-state data.
The new sample package solves the standing difficulty of static compression experiments to pressures higher than 300 gigapascals. Says Livermore scientist Claire Zurkowski, the paper’s first author, “We anticipate that this sample-encapsulation method will readily push static equation-of-state calibrations in physics, chemistry, and planetary science materials into the multi-megabar range—conditions where static compression data is very limited at present.”
Contact: Claire Zurkowski (925) 422-8121 (zurkowski1 [at] llnl.gov (zurkowski1)zurkowski1 [at] llnl.gov (@llnl.gov)).
Enhanced Powder Absorptivity in 3D Printing
One of the persistent challenges in laser powder bed fusion (LPBF) 3D printing is the high reflectivity of certain metals, which can lead to inefficient energy absorption and inadequate print quality. Lawrence Livermore researchers in collaboration with scientists from Stanford University and the University of Pennsylvania have introduced a wet chemical etching process that modifies the surface of metal powers, enabling a more effective energy transfer during laser melting. Their study appears on the cover of the September 6, 2024, issue of Science Advances.
The new process creates nanoscale grooves and textures that increase absorptivity of metal powders used in LPBF without compromising purity or properties, such as high thermal and electrical conductivity, that make copper and other metals desirable for 3D-printed objects. The team printed high-purity copper and tungsten structures using lower energy input: less than 100 Joules per cubic millimeter (J/mm3) for copper (a value closer to the typical range for high-density titanium and stainless-steel alloys), and approximately 700 J/mm3 for tungsten (about one-third of the energy typically used).
Enhancing metal powder absorptivity is a promising step toward reducing additive manufacturing costs as well, particularly as the demand for more efficient manufacturing processes continues to grow. “With standard commercial laser-based machines, high-quality pure copper metal additive manufacturing is considered infeasible,” says co-author and Livermore materials scientist Philip DePond. “We are enabling copper printing without the risk of damaging existing machines or the expense of building new machines to process highly reflective materials.”
Contact: Philip DePond (925) 422-0235 (depond1 [at] llnl.gov (depond1[at]llnl[dot]gov)).
A New Treatment for the Effects of Fentanyl
Fentanyl’s lethal effects have killed more than 210,000 Americans in the last three years. The primary drug used to treat fentanyl overdoses, Naxolone (or Narcan), is effective but has a half-life of between 30 and 80 minutes, so it must be readministered to maintain activity in the body. A team of Laboratory researchers has discovered a new treatment to counteract the effects of fentanyl and related opioids. Called Subetadex, the drug has a half-life of 7.5 hours. Their results are published in the October 23, 2024, issue of ACS Central Science.
The Livermore team used nuclear magnetic resonance (NMR) to test the binding of various potential treatment compounds to opioids. These researchers were the first to test the compound Subetadex, discovered in 2002, against fentanyl, finding that Subetadex encapsulated fentanyl and prevented it from binding to receptors in the body. Recovery times for in vivo experiment models exposed to sublethal fentanyl doses were significantly reduced when Subetadex was administered.
This discovery of Subetadex’s effectiveness offers potential for the development of a medical countermeasure against the effects of fentanyl. “Using NMR, we found that the Subetadex binds to fentanyl quite well and does not let go of it,” says Carlos Valdez, principal investigator for the fentanyl medical countermeasure initiative. “That was a big moment. Finding a compound that already offers benefits is an exciting discovery because, as chemists, we know we can modify the compound to make it perform even better.”
Contact: Carlos Valdez (925) 423-1804 (valdez11 [at] llnl.gov (valdez11[at]llnl[dot]gov)).
