In collaboration with researchers at the University of California at San Francisco (UCSF), Lawrence Livermore scientists developed a novel system for recording widespread brain activity using high-density, implantable electrode arrays. The research appears in the January 2, 2019, edition of Neuron. As described in the paper, the system is capable of continuously recording the activity of nearly 400 single neurons over a period of at least five months from devices distributed in multiple brain regions.
UCSF scientists implanted 16 arrays (each consisting of 64 electrodes) across four distant regions of the brain: the hippocampus, ventral striatum, orbitofrontal cortex, and medial prefrontal cortex. The multielectrode arrays, which are made from a biocompatible, flexible polymer material, were fabricated at Livermore and combined with electrical hardware built by neuroscience tool manufacturer SpikeGadgets. Using an automated spike-sorting system developed at UCSF, the researchers concluded the recordings are stable enough to allow them to track large numbers of individual neurons for more than a week.
The team says the system provides a new tool for understanding brain activity and makes it possible to examine how different regions of the brain interact. “The ability to record activity from multiple regions of the brain for long periods of time with high fidelity allows us to start looking at patterns of learning and how memory changes,” says Livermore researcher Angela Tooker, a co-author on the paper. Such a capability could make it possible to understand how the brain processes information that can take days, weeks, or even months, such as forming, consolidating, and retaining memories.
Contact: Angela Tooker (925) 422-2326 (tooker1@llnl.gov).
For decades, nuclear scientists have been trying to harness the energy produced by the thermonuclear fusion of deuterium (D) and tritium (T) nuclei to power reactors of the future. Now, a Livermore team has for the first time used validated models of the interactions of neutrons and protons (the constituents of nuclei) and an ab initio reaction method to accurately predict the properties of polarized DT thermonuclear fusion. The research appears in the January 21, 2019, edition of Nature Communications.
Thermonuclear fusion is a type of nucleosynthesis in which lighter elements, such as hydrogen and helium, are converted into heavier ones, and in the process release large amounts of energy. In the study, Livermore researchers combined a first-principles approach with high-performance computing to model thermonuclear reactions. By using a state-of-the-art approach for studying the structure and dynamics of atomic nuclei—the ab initio no-core shell model with continuum—they were able to predict how the DT fusion rate changed based on spin polarization and temperature. The team is interested in polarized DT thermonuclear fusion wherein the D and T nuclei “spin” in the same direction, which could enhance the fusion rate by as much as 50 percent. The charged helium nuclei produced in the fusion reaction could be more efficiently focused to heat up reactor fuel.
Thermonuclear fusion occurs naturally in stars, which are fueled by nucleosynthesis, and also plays an important role in explaining the primordial abundances of elements after the Big Bang. Thus, thermonuclear reactions are of great interest to astrophysicists who seek to answer some of the most fundamental questions about the origins of the universe and the evolution of stars. Livermore physicist Sofia Quaglioni, one of the authors of the paper, says, “In the future, analogous calculations could be used alongside available experimental results to provide the thermonuclear reaction data and level of accuracy required to improve the predictivity of astrophysics simulations.”
Contact: Sofia Quaglioni (925) 422-8152 (quaglioni1@llnl.gov).
Laboratory researchers have used three-dimensional (3D) printing to produce live cells that convert glucose to ethanol and carbon dioxide gas (CO2)—a substance that resembles beer. The research, which appears as an ACS (American Chemical Society) Editors’ Choice article in the January 31, 2019, edition of Nano Letters, shows that additively manufactured live whole cells can assist in studies of microbial behaviors, communication, interaction with the microenvironment, and new bioreactors with high productivity.
Microbes are extensively used in industry to convert carbon sources into valuable end-product chemicals that have broad applications. In the Livermore case study, the team incorporated freeze-dried live biocatalytic yeast cells into porous 3D structures using a new bioink material. The printed structures are large-scale and self-supporting, with high resolution, tunable cell densities, high catalytic activity, and long-term viability. More importantly, if genetically modified yeast cells are used, high-value pharmaceuticals, chemicals, food, and biofuels can also be produced.
“The bioprinted 3D geometries developed in this work could serve as a versatile platform for process intensification of an array of bioconversion processes using diverse microbial biocatalysts for production of high-value products or bioremediation applications,” says Livermore materials scientist Fang Qian, the project lead and corresponding author on the paper. Engineer and co-author Eric Duoss adds, “This approach promises to make ethanol production faster, cheaper, cleaner, and more efficient. Now, we are extending the concept by exploring other reactions, including combining printed microbes with more traditional chemical reactors to create ‘hybrid’ or ‘tandem’ systems that unlock new possibilities.”
Contact: Fang Qian (925) 424-5634 (qian3@llnl.gov).