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Los Alamos National Laboratory

Los Alamos National Laboratory

Delivering science and technology to protect our nation and promote world stability

STE Highlights, April 2020

Awards and Recognition

Langendorf and Wurden selected for ARPA-E awards

The Plasma Liner Experiment at LANL

The Plasma Liner Experiment at LANL

Samuel Langendorf and Glen Wurden of the Plasma Physics Group (P-24) were selected for Department of Energy Advanced Research Projects Agency-Energy (ARPA-E) funding awards. The awards are part of the Breakthroughs Enabling Thermonuclear-fusion Energy (BETHE) program, working to develop commercially viable fusion energy. Fusion holds great potential to be a safe, clean, and reliable energy source, but research and development has been constrained by prohibitive costs.

Langendorf and Wurden represent two of the 15 funded projects. One of the LANL projects is aimed at developing lower-cost concepts while the other is aimed at providing a suite of capabilities to accelerate multiple concepts.

To enable lower cost, LANL’s Plasma Liner Experiment facility will be employed for a novel fusion energy approach—plasma-jet driven magneto-inertial fusion. This concept will use a spherical array of plasma guns to form a spherically imploding plasma shell, or liner, which compresses and heats a pre-injected magnetized plasma target.

The second LANL project will provide a suite of proven vacuum ultraviolet and soft x-ray diagnostics, including movies of a hot plasma core. These capabilities will characterize the performance of a number of lower-cost, potentially transformative fusion-energy concepts.

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Myers selected as American Statistical Association (ASA) Fellow

Kary Myers

Kary Myers

Kary Myers, Deputy Group Leader of Statistical Sciences (CCS-6) at Los Alamos, was recently selected as a Fellow of the American Statistical Association (ASA).

The designation of ASA Fellow is a significant high honor—awarded annually to no more than one-third of one percent of the American Statistical Association membership. In order to be selected, nominees must have an established reputation and have made outstanding contributions to statistical science.

Myers was recognized for her creative leadership, innovative development and application of statistical methods for high impact collaborations, statistical outreach to the broader statistical community, and outstanding service to the statistics profession.

The ASA Fellow Award will be officially presented at the August 2020 Joint Statistical Meetings in Philadelphia, Penn.

Technical contact: Kary Myers

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Pilania recognized as Rising Star

Ghanshyam Pilania

Ghanshyam Pilania

Ghanshyam Pilania, of Materials Science in Radiation and Dynamics Extremes (MST-8) is a finalist for the second Rising Stars in Computational Materials Science special issue and prize. The initiative recognizes the accomplishments and promise of researchers in the early stages of their independent careers and draws international attention to their work.

As a finalist, Pilania has been invited to submit a review paper of his research by Oct. 31, 2020. The review will be included in a virtual special issue of Computational Materials Science devoted to the Rising Stars. This paper will be evaluated by the journal editors for the 2020 prize.

“This award provides a unique opportunity for me to share my research excitement with the community,” Pilania said.

Pilania’s research focuses on the development and application of materials modeling tools for scales ranging from electronic to atomic to meso. He is particularly interested in quantum mechanical simulations and materials informatics approaches to understand structure-processing-performance mappings in a wide range of functional materials.

Technical contact: Ghanshyam Pilania

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Bioscience

New ultra-high-throughput capability for biocatalyst screening

Los Alamos researchers in the Bioscience (B) Division and collaborators created a new capability for rapidly discovering—and evolutionarily enhancing—biocatalysts needed in the production of food, pharmaceuticals, specialty chemicals, renewable energy, and environmental cleanup, altogether a $7 billion industry.

Called Smart Microbial Cell Technology, the capability is based on a custom-made sensor–reporter gene circuit. When coupled with the high-throughput capability of flow cytometry, the technology can screen whole cell or enzyme biocatalysts at a rate of about one million per day.

Ramesh Jha demonstrates the Smart Microbial Cell Technology on a petri dish. This is one of the three possible methods for employing the technology.

Ramesh Jha demonstrates the Smart Microbial Cell Technology on a petri dish. This is one of the three possible methods for employing the technology.

“The limiting factor in biocatalyst screening has been the throughput, and our technology addresses that limitation. It is orders of magnitude faster than current state-of-the-art techniques, such as screening using micro-titer plates,” said Ramesh Jha, the technology’s technical lead.

Biocatalysts are specific, like a key in a lock

Biocatalysts do not fall into the one-size-fits-all category. Each reaction requires its own specific and optimized biocatalyst to help transform molecules into final products. But industrially useful reactions suffer from non-optimal activity and stability of biocatalysts, and nature has barely evolved anything for anthropogenic molecules, such as plastics or pesticides. There is a significant need for precise and optimized biocatalysts that can push each of these critical reactions.

With each reaction needing a specialized biocatalyst, pace becomes an issue. But it takes time to discover a biocatalyst that possesses gain-of-function mutations because these mutations are extremely rare and finding them is like searching for a needle in a haystack. It requires hunting through large libraries of possible biocatalysts and possible mutations for any given performance enhancement.

The Smart Microbial Cell Technology makes the screening process faster and simpler. For example, in a recent paper by the researchers, this technology was used to enhance muconate production three-fold. Muconate is vital to the non-petrochemical production of polymer products, such as nylon and polyethylene terephthalate (PET). Their success was based on the custom development of a muconate sensor, which led to the discovery of tunable regions in the biocatalyst. From there, the researchers were able to build a more productive biocatalyst.

Other benefits of the new technology

The Smart Microbial Cell Technology is an ultrafast screening method for biocatalysts, and at the same time, it’s extremely cost effective and simple. It requires only a fraction of the chemical reagents and consumables used in other methods. For example, what can be accomplished with a traditional method using 100,000 plastic 96-well micro-titer plates and 1,000 L of reagents can be accomplished with the new technology in a single small tube with 1 mL of reagents. It is a significant economic improvement.

The needed equipment and personnel are also more streamlined. Smart Microbial Cell Technology does not require complex machinery or highly trained personnel. It can be performed with a flow cytometer to boost the throughput, but it can also be performed without it, albeit with a slight drop in throughput. It’s a flexible technology. This removes yet another bottleneck in the biocatalyst screening process while offering more accurate direct detection of the biocatalytic reaction.

“With an ultra-high-throughput capability, the Smart Microbial Cell Technology will pave the way for discovery and de novo synthesis of novel biocatalysts, which can be applied for biosynthesis and bioremediation of xenobiotic molecules with an effort to move towards a sustainable environment,” said Jha.

Funding and mission

This technology was developed through funding acquired from the Defense Threat Reduction Agency and DOE Office of Energy Efficiency and Renewable Energy’s Bioenergy Technologies Office (BETO) through Agile BioFoundry. The work supports the Laboratory’s Global Security mission area and the Science of Signatures and the Complex Natural and Engineered Systems.

References: United States Application Number 16/226,474 “Modified biosensors and biocatalysts and methods of use.”

Bentley GJ (National Renewable Energy Lab), Narayanan N, Jha RK, Salvachua D, Elmore JR (Oak Ridge National Lab), Peabody GL, Black B, Ramirez K, De Capite A, Michener W, Werner A, Klingeman D, Schindel H, Nelson R, Foust L, Guss AM, Dale T, Johnson CW, Beckham GT. “Engineering glucose metabolism for enhanced muconic acid production in Pseudomonas putida KT2440.” Metabolic Engineering (2020), 59, 64–75. https://doi.org/10.1016/j.ymben.2020.01.001

Jha RK, Narayanan N, Pandey N, Bingen J, Kern TL, Johnson CW (National Renewable Energy Lab), Strauss CEM, Beckham GT, Hennelly SP, Dale T. “Sensor-enabled alleviation of product inhibition in chorismate pyruvate-lyase.” ACS Synthetic Biology (2019), 8(4), 775–786. https://doi.org/10.1021/acssynbio.8b00465

K. Jha and C. E. M. Strauss. "Smart microbial cells couple catalysis and sensing to provide high throughput selection of an organophosphate hydrolase." Accepted April 2020 to ACS Synthetic Biology

Technical contacts: Ramesh Jha, Taraka Dale, and Charlie Strauss

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Chemistry

LANL-developed catalyst complexes now available through Strem Chemicals, Inc.

Los Alamos researchers in Chemistry, Bioscience, and Materials Physics Applications Divisions developed new ruthenium-based catalyst complexes that are now commercially available through Strem Chemicals, Inc. Strem is an international company that specializes in high-quality, high-purity chemicals.

A new LANL-developed ruthenium catalyst was featured on the March alternate cover of Organic Process Research and Development.

A new LANL-developed ruthenium catalyst was featured on the March alternate cover of Organic Process Research and Development.

Although there are catalysts on the market aimed at performing the same task as the new complexes—synthesizing functionalized primary alcohols and fluoral hemiacetals—the new catalysts offer greater selectivity and turnover efficiency. These LANL-developed complexes are the new state-of-the-art for reactions that produce building blocks for pharmaceuticals, agrochemicals, perfumes, and more.

New study shows LANL catalysts outperform competitors

Up until now, the top catalysts for selective hydrogenation of esters into functionalized alcohols were Ru-MACHOTM ruthenium complexes from Japan and Gusev’s Ru-SNS complexes from Canada. Both are advantageous in that they work under mild reaction conditions.

Structure of one of the LANL-developed ruthenium catalysts, referred to as Ru-2a. This catalyst was shown to significantly outperform competitors.

Structure of one of the LANL-developed ruthenium catalysts, referred to as Ru-2a. This catalyst was shown to significantly outperform competitors.

Los Alamos researchers showed that their ruthenium complexes, called Ru-SNP(O)z, not only perform the same reaction processes as the competitor catalysts, but in many cases the Los Alamos-developed complexes outperform in terms of selectivity and turnover number—both important factors for catalyst cost and product yield. Less of the catalyst is needed to perform the same reaction.

Biomass is better for the environment

The LANL-developed catalysts can create the needed fine chemical building block products from biomass. The Department of Energy has a goal to replace 25% of industrial petroleum-derived organic chemicals with biomass-derived chemicals by 2025. This is because petroleum is a fossil fuel and contributes to greenhouse gas production.

The LANL catalysts solve some of the performance issues hindering the widespread use of biomass. Examples of these problems include loss in optical purity and chemoselectivity. The LANL catalysts were shown to actually increase selectivity of needed reactions.

Funding and mission

Funding for this research was provided by the LANL Laboratory Directed Research and Development (LDRD) program. Computations were performed using the LANL Darwin Computational Cluster. The work supports the Laboratory’s Energy Security mission area and the Materials for the Future capability pillar.

Technical contact: Pavel Dub

Reference: Pavel A. Dub, Rami J. Batrice, John C. Gordon, Brian L. Scott, Yury Minko, Jurgen G. Schmidt, and Robert F. Williams. “Engineering Catalysts for Selective Ester Hydrogenation.” Org. Proc. Res. Dev. 2020, 24(3), 415–442. https://pubs.acs.org/doi/10.1021/acs.oprd.9b00559

Related links: STREM Chemicals, Inc. product page:

Catalyst: https://www.strem.com/catalog/v/44-3210/59/ruthenium_1802182-33-7

Ligand: https://www.strem.com/catalog/v/15-4625/52/phosphorus_1802182-42-8

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Intelligence and Space Research

First model to couple extreme space weather events to power grid infrastructure

A Los Alamos model, called the Carrington-GIC, is the first global physics-based model to couple geomagnetic disturbances to power grids on Earth. This information is quite valuable because electromagnetic disturbances caused by geomagnetic storms can severely damage power transmission systems.

The successful model is now being looked at in relation to nuclear weapons—answering questions about the effects of high-altitude nuclear explosions (HANE).

An overview of the technology concept.

An overview of the technology concept.

A model named for the Carrington Event

In 1859, the Earth experienced the most powerful geomagnetic storm ever recorded. It was dubbed the Carrington Event (after Richard Carrington, who meticulously documented the initial optical disturbance from the Sun.) However, in the mid-nineteenth century, the only susceptible technological systems were long-distance telegraph lines, and during the Carrington Event, some telegraph offices actually caught on fire. A storm of similar magnitude today could potentially cause long-term blackouts and severe damage to the power grid as well as other long-distance conducting infrastructures such as communication lines, pipelines, and railroads. Simulating conditions that give rise to that damage offers valuable knowledge for decision-makers and the public.

The Carrington Geomagnetically Induced Current model, or Carrington-GIC, is the first global physics-based model to offer simulations that couple extreme space weather, such as a large geomagnetic event, to our power grids. However, the model can also be used to examine smaller events of longer duration because those too can lead to premature failure of critical power grid components, including step-up and step-down transformers that are placed between long-distance high-voltage transmission lines. These transformers are the most susceptible and can become severely damaged or even destroyed during extreme events.

The model also takes into account spatial variations in the Earth’s ground conductivity, which significantly complicates the coupling of space-based geomagnetic disturbances into the ground-based conductive technological systems. Such geological variations have been shown to rotate the induced electric fields on relatively small scales. Previous global physics-based models have not taken this important factor into account.

The Carrington-GIC model uses the framework of SHIELDS—a LANL technology that won an R&D 100 award in 2017.

The Carrington-GIC model uses the framework of SHIELDS—a LANL technology that won an R&D 100 award in 2017.

Carrington-GIC extends to nuclear weapons effects

The model has successfully simulated realistic extreme natural events and their impacts on the power grid, and elements of the model are now being used to study HANE. The electro-magnetic pulse (EMP) effects from a HANE can be divided into three main categories: E1, E2, and E3 signals. It turns out that natural geomagnetic storm disturbances produce a ground effect that is somewhat similar to parts of the EMP/E3 HANE disturbance (which is currently not well-modeled). Thus, the Carrington-GIC model is being extended to help better understand the HANE EMP/E3 effect.

“Essentially, the geomagnetic storms are a surrogate for studying the E3 signal,” says Mike Henderson, principal investigator. “Our next goal is to tailor our Carrington-GIC model to the HANE EMP/E3 problem.”

Funding and mission

This research was funded by a LANL Laboratory Directed Research and Development award. The work supports the Laboratory’s Nuclear Deterrence mission area and the Science of Signatures and Weapons Systems capability pillars.

Reference: S. K. Morley, D. T. Welling, J. R. Woodroffe. “Perturbed input ensemble modeling with the space weather modeling framework.” Space Weather. 16, 1330–1347. https://doi.org/10.1029/2018SW002000

Technical contact: Mike Henderson

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Nuclear Engineering and Nonproliferation

Los Alamos partners with Sweden for new spent-fuel NDA method

A team of Los Alamos researchers and students from the Nuclear Engineering and Nonproliferation (NEN) Division built a nondestructive assay (NDA) instrument to test a new method for spent nuclear fuel analysis. Called differential die-away self-interrogation (DDSI), the new method uses the die-away of neutrons from spontaneous and induced fissions to characterize a spent nuclear fuel assembly. DDSI is the only existing power reactor fuel measurement system capable of neutron coincidence counting with list-mode data collection, which details the time of arrival of neutrons in every channel.

Schematic of the differential die-away self-interrogation (DDSI) instrument showing orientation in the facility and pods used in the field trials (P2 and P3) with output channels labeled.

Schematic of the differential die-away self-interrogation (DDSI) instrument showing orientation in the facility and pods used in the field trials (P2 and P3) with output channels labeled.

This research was published in Nuclear Instruments and Methods in Physics Research and featured in the February 2020 National Nuclear Security Administration (NNSA) publication the DNN Sentinel.

Characterizing spent fuel is the most challenging special nuclear material (SNM) characterization because of the high levels of radiation in spent fuel, the complex dynamic of fuel evolution while producing power and afterwards, the heterogeneity of the fuel, and other challenges. The results in this work demonstrate the DDSI concept is capable of characterizing spent power reactor fuel with levels of accuracy that are compatible with the requirements and objectives of various applications such as safeguards verification or facility material control and accounting.

DDSI is unique and accurate

Los Alamos created the instrument and method and sent it to the Central Interim Storage Facility for Spent Nuclear Fuel (Clab) in Sweden for spent fuel assembly field trials—the culmination of a 10-year effort to qualify and deploy DDSI.

The field trials consisted of 25 spent pressurized water reactor and 25 spent boiling water reactor fuel assemblies. More than 40 hours of neutron list-mode data were obtained, and each assembly was assessed for the following characteristics: multiplication, elemental plutonium mass, initial enrichment, burnup, cooling time, and fissile mass.

The work demonstrated DDSI is capable of accurately characterizing spent power reactor fuel. This nondestructive method offers comparable results to current safeguards verification and facility material control and accounting.

The differential die-away self-interrogation (DDSI) instrument, shown here, uses the die-away of neutrons from spontaneous and induced fissions to characterize a spent nuclear fuel assembly.

The differential die-away self-interrogation (DDSI) instrument, shown here, uses the die-away of neutrons from spontaneous and induced fissions to characterize a spent nuclear fuel assembly.

How DDSI works

One at a time, each spent assembly was lifted from its storage container and lowered underwater into the DDSI funnel opening for a 20–30-minute static measurement. The DDSI consists of four pods, each filled with 14 3He tubes for measuring time-correlated neutrons from spontaneous and induced fissions. The signals from the 3He tubes were transmitted to a specialized data acquisition system. In this way, the time of arrival of neutrons in every channel was recorded.

DDSI was able to address a number of technical problems, including verifying the initial enrichment, burnup, and cooling time of facility declaration; detecting the diversion or replacement of pins within an assembly; estimating fissile mass; estimating decay heat; and determining the reactivity of spent fuel assemblies. The information gleaned from an instrument like DDSI will provide useful characterization for verification and accountability.

Funding and mission

This work was funded by NNSA’s International Nuclear Safeguards program DNN’s Office of International Nuclear Safeguards. The work supports the Laboratory’s Nuclear Deterrence mission area and the Nuclear and Particle Futures capability pillar.

Reference: Alexis C. Trahan, Garrett E. McMath, Paul M. Mendoza, Holly R. Trellue, Ulrika Backstrom (Swedish Nuclear Fuel and Waste Management Company), Li Pöder Balkeståhl (Uppsala University), Sophie Grape, Vlad Henzl, Daniel Leyba, Margaret A. Root, Anders Sjoland. “Results of the Swedish spent fuel measurement field trials with the Differential Die-Away Self-Interrogation Instrument.” Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. March 2020. https://doi.org/10.1016/j.nima.2019.163329

Technical contact: Paul Mendoza

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Physics

New inertial confinement fusion measurement: Neutron imaging diagnostic is a first

Los Alamos researchers, working with Lawrence Livermore National Laboratory and Imperial College collaborators, have designed a novel inertial confinement fusion (ICF) diagnostic . The neutron imaging diagnostic was put in place at the National Ignition Facility (NIF) in Livermore, Calif., and investigated via experiment and simulation. The findings were published in the Journal of Applied Physics and selected as the cover for Volume 127, Issue 8.

This research was selected for the cover of the American Institute of Physics Issue 8 Journal of Applied Physics. Credit: AIP Publishing

This research was selected for the cover of the American Institute of Physics Issue 8 Journal of Applied Physics. Credit: AIP Publishing

Fusion ignition holds promise of abundant energy

ICF is a type of fusion energy research in which initiation reactions occur by heating and compressing deuterium–tritium fuel. As of yet, ignition has not occurred, but progress like this new diagnostic will help researchers get there. The goal of NIF is to eventually provide abundant and sustainable clean energy from nuclear fusion.

These researchers sought to answer questions related to hot-spot ignition of the core. To understand local deuterium–tritium fuel density, the neutron imaging diagnostic offered two important images: one of the primary neutrons produced by the fusion reaction and the other of the downscattered neutrons that leave the reaction. Along with the images, a set of linear equations related information within the two types of images, which led to a quantitative understanding of the density distribution in the fuel region. This is the first time a measurement like this has been made.

Specifically, a limited-view 3D tomography of the burning hot spot was obtained as well as novel information on the absolute density of the cold fuel. Density is one of the primary variables in the criteria for ignition. Therefore, these data are ideally suited to draw conclusions on fusion performance in comparison to simulations.

An illustration of the quantitative agreement between reconstructed and simulated burn volumes for a limited-view reconstruction with three lines of sight.

An illustration of the quantitative agreement between reconstructed and simulated burn volumes for a limited-view reconstruction with three lines of sight.

Taking this diagnostic further

The novel diagnostic showed quantitative agreement between reconstructed and simulated burn volumes. However, there were limitations with the system and method. Using a single line of sight was one such limitation, and using a single-scattering approximation was another. The researchers are already working to mitigate these limitations.

Improving upon this basic framework will aid in drawing further ICF conclusions and placing reliable uncertainties on additional physical quantities (i.e., pressure and temperature).

Funding and mission

This work, performed under the auspices of the DOE for the NNSA Inertial Confinement Fusion Science Campaign (LANL Program Manager John Kline), supports the Laboratory’s Energy Security mission area and the Nuclear and Particle Futures capability pillar.

Reference: Petr L. Volegov, Verena Geppert-Kleinrath, Christopher R. Danly, Carl Wilde (Neutron Science and Technology, P-23); Steven H. Batha (Plasma Physics, P-24); Frank Merrill (XTD Primary Physics, XTD-PRI); Douglas Wilson (Plasma Theory and Application, XCP-6); Daniel T. Casey, David Fittinghoff (Lawrence Livermore National Laboratory); Brian Appelbe, Jeremy Chittenden, Aiden J. Crilly, and Kris McGlinchey (Imperial College). “Density determination of the thermonuclear fuel region in inertial confinement fusion implosions,” Journal of Applied Physics. 127, 8 (2020). https://doi.org/10.1063/1.5123751

Technical Contact: Petr Volegov

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Sigma

Defect engineering: A first for tuning molecular crystal properties

Molecular crystals inevitably have some defects, but how those defects affect mechanical material properties hasn’t been well understood. If these impacts could be quantified, simulated, and predicted, defects could actually be engineered into molecular crystals to “tune” their material properties. In this sense, it is cleverly learning to make lemonade when given lemons.

LANL artwork represents the crystal research. This will be considered for the journal cover.

LANL artwork represents the crystal research. This will be considered for the journal cover.

Researchers from LANL’s Sigma Division and the Center for Integrated Nanotechnologies (CINT) in collaboration with researchers at Georgetown University recently made the first measurements and quantifications of property changes after introducing engineered defects into uric acid crystals.

"The low level of impurities we used in this study clearly caused very large changes to mechanical response, and there appear to be differences in how these materials respond compared to other classes of materials,” said Dan Hooks, Sigma Division.

Engineered defects will improve a range of applications

Molecular crystals are common across several industries including semiconductors, energetic materials, and pharmaceuticals, for example. A perfect crystal would be seen as an uninterrupted repeating pattern of molecules, but there are no perfect crystals, whether due to impurities or other imperfections during crystal growth.

Most impurities have unknown chemical identities and concentrations, but the Los Alamos researchers removed these variables in order to correlate impurity characteristics with mechanical properties. They doped anhydrous uric acid crystals with two different dyes—a blue and a red—to detect and quantify their incorporation into the crystal lattice.

A comparison of lattice structure in uric acid (UA), UA doped with blue dye (UA-MB), and UA doped with red dye (UA-BBY).

A comparison of lattice structure in uric acid (UA), UA doped with blue dye (UA-MB), and UA doped with red dye (UA-BBY).

The researchers found an interesting phenomenon. At low dopant concentrations, they found increased plasticity, but at high concentrations they found increased material strength. This suggests that crystal properties can in fact be honed through dopants with specified compositions and concentrations.

This study was the first to unambiguously link defect concentrations and mechanical properties in a molecular crystal system. The concentrations were also particularly relevant as they simulate typical impurity levels in commodity chemicals.

Funding and mission

This work was funded by the National Science Foundation (NSF). This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy Office of Science.

Reference: Fan Liu (Georgetown University), Daniel E. Hooks, Nan Li, Judith Faye Rubinson, Jennifer N. Wacker, and Jennifer A. Swift. “Tuning Molecular Crystal Mechanical Properties via Defect Engineering.” Accepted April 2020. DOI: 10.1021/acs.chemmater.0c0043

Technical contact: Dan Hooks

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Theoretical

Groundbreaking actinide research: The discovery of unique metal–ligand bonding

Researchers in the Los Alamos Theoretical (T) Division discovered two new types of metal–ligand bonding in actinide metal complexes. How orbitals align within a complex plays into the chemical bonding, and f-elements offer particularly exotic opportunities.

The alignments seen in the new bonds include “head-to-side” δ in metallacyclopropenes and “side-to-side” φ back-bonding in metallacyclocumulenes. These new bonds are the first to defy the typical bond length contraction trend that usually happens in actinide complexes, underscoring the importance of the discovery.

Unpaired f-electrons (1c-1e) on the metal centers in the cumulene series. (a) One f-electron of Pa. (b) Two f-electrons of U. (c) Three f-electrons of Np. (d) Four f-electrons of Pu.

Unpaired f-electrons (1c-1e) on the metal centers in the cumulene series. (a) One f-electron of Pa. (b) Two f-electrons of U. (c) Three f-electrons of Np. (d) Four f-electrons of Pu.

 

Research includes uranium and plutonium

Los Alamos is the Plutonium Center of Excellence, and understanding actinides is a primary Lab mission. The chemistry and corresponding behavior of actinides are often quite complex and exotic.

This study, which was published in Nature Communications, looked at known complexes of thorium and uranium propenes and cumulenes as well as accurately predicted complexes of protactinium, neptunium, and plutonium. Structures of the complexes were optimized via Density Functional Theory with the PBE functional. The chemical bonding was analyzed with the AdNDP method. Although the techniques were simulation based, the models were shown to well represent reality.

The researchers were able to explain in detail the increase in actinide–ligand bond length across the actinide series. In particular, the δ and φ back-donations are crucial in explaining this non-classical trend.

Understanding this type of bonding and the role it plays in actinide complexes aides in simulation, prediction, and experiment. Actinides are vital to our national security, and better understanding their chemistry firmly supports our mission.

Funding and mission

The work was partially sponsored by the Department of Energy, Chemical Sciences, Geosciences, and Biosciences Division, Heavy Element Chemistry Program. A portion of the research was performed using EMSL, a DOE Office of Science User Facility sponsored by the Office of Biological and Environmental Research. The research supports the Laboratory’s Nuclear Deterrence mission area and the Nuclear and Particle Futures and the Science of Signatures capability pillars.

Reference: Morgan Kelley, Ivan Popov, Julie Jung, Enrique Batista, and Ping Yang. “δ and φ back-donation in AnIV metallacycles.” Nature Communications. 2020, 11, 1558. DOI: 10.1038/s41467-020-15197-w

Related: Katrina Kramer. “New type of bond is the first to defy actinide contraction trend.” Chemistry World. March 2020.

Technical contact: Enrique Batista

LANL releases novel open-source software for environmental and ecosystem-based applications

Amanzi/ATS software, developed by Los Alamos and collaborators, is a powerful new computer simulation tool for scientists and engineers working on some of society’s most pressing environmental issues, including climate change impacts, water availability, and contaminant transport.
David Moulton, left, and Rao Garimella demonstrate Amanzi’s simulation capability for contaminant flow.

David Moulton, left, and Rao Garimella demonstrate Amanzi’s simulation capability for contaminant flow.

Amanzi/ATS allows scientists and engineers to simulate entire environmental systems with unprecedented detail in the representation of key biogeochemical, biophysical, and ecohydrological processes.

“Amanzi has been used to model contaminant migration at various Department of Energy legacy waste sites, including the Nevada National Security Site and Hanford,” said David Moulton, principal investigator at Los Alamos. “And ATS has been used to model surface and subsurface hydrology in the Arctic tundra.”

Amanzi/ATS was released March 31, 2020, through GitHub, an open-source software platform. This dual invention is the brainchild of Los Alamos researchers in the Theoretical Division along with collaborators at several national laboratories: Lawrence Berkeley, Oak Ridge, and Pacific Northwest.

The software is both open source and open code, allowing for tailored modification and custom applications. It is the only software of its kind that can address any environmental research problem—big or small—to offer quantitative solutions and allow for collaborations among worldwide agencies.

Amanzi simulates coupled surface, subsurface systems

The researchers developed Amanzi first. Amanzi, which means water in the Zulu language, is a multiphysics framework that provides unprecedented flexibility—variables can be altered at any stage of the simulation. There is feedback and flow, a must when modeling something as dynamic as nature, and what is learned in a given subcycle of modeling can be input into the next cycle.

Amanzi’s framework is called Arcos. This framework is used in combination with a mesh infrastructure, which allows for splitting and subsetting of information. Together, this is a powerful modeling software that can be adapted to look at surface, subsurface, and coupling of the two. No other software for environmental applications can perform such tasks.

In the example of applying Amanzi to legacy waste, the software predicts how contaminants (such as uranium) will move through groundwater. Knowing where the contaminant will go enables decision-makers to strategically place physical barricades underground to prevent widespread contamination.

Advanced Terrestrial Simulator expands Amanzi capabilities

Advanced Terrestrial Simulator (ATS) was then built on top of the Amanzi framework. ATS is a code that was created in response to climate questions in the Arctic.

As the Arctic permafrost cycles through freeze/thaw, the overall thickness of the permafrost continues to decrease, a consequence of climate change that can now be modeled via ATS. The ATS code models sources and sinks, which are specific to climate models, and incorporates thermal processes, evapo-transpiration, albedo-driven surface energy balances, snow, biogeochemistry, plant dynamics, deformation, transport, and much more.

Together, Amanzi/ATS is a flexible and powerful solution to modeling the complex and constantly changing variables of environmental systems, such as permafrost cycles.

Funding and mission

Amanzi/ATS is a joint collaboration among LANL, Lawrence Berkeley National Lab, Oak Ridge National Lab, and Pacific Northwest National Lab. The work supports the Laboratory’s Global Security mission area and the Integrating Information, Science, and Technology for Prediction capability pillar.

References: GitHub release page https://amanzi.github.io/

Berre, I. et al., 2020. “Verification benchmarks for single-phase flow in three-dimensional fractured porous media.” Advances in Water Resources. https://arxiv.org/abs/2002.07005

Abolt, C.J. et al., 2020. “Feedbacks between surface deformation and permafrost degradation in ice wedge polygons, Arctic Coastal Plain, Alaska.” Journal of Geophysical Research: Earth Surface. 125, p.e2019JF005349. https://doi.org/10.1029/2019JF005349

Technical contact: David Moulton

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