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At least 649 records · Page 36

A noncollinear density functional theory ansatz for the phononic and thermodynamic properties of α -Pu

Plutonium's phase diagram is host to complex structures and interactions that make the description of its ground state properties elusive. Using all-electron density functional theory calculations, we study the thermodynamic properties of α-Pu. To do this, we build on recent work in the literature by introducing a novel noncollinear magnetic ansatz for α-Pu's ground state. We show that the noncollinear ansatz improves the description of the experimental phonon density of states, heat capacity, and thermal expansion over previous results obtained with a collinear ansatz. Here, despite lacking a bond-equivalent picture of the bonding, these new results for α-Pu, along with recent results on δ-Pu, demonstrate the efficacy of noncollinear ansatzes for the description of plutonium.

36 MATERIALS SCIENCE↗

Exceptional energy and new insight with a sodium–selenium battery based on a carbon nanosheet cathode and a pseudographite anode

We created a unique sodium ion battery (NIB, SIB) cathode based on selenium in cellulose-derived carbon nanosheets (CCNs), termed Se-CCN. The elastically compliant two-dimensional CCN host incorporates a high mass loading of amorphous Se (53 wt%), which is primarily impregnated into 1 cm 3 g -1 nanopores. The results in facile sodiation kinetics due to short solid-state diffusion distances and a large charge transfer area of the nanosheets were established. The architecture also leads to an intrinsic resistance to polyselenide shuttle and to disintegration/coarsening. As a Na half-cell, the Se-CCN cathode delivers a reversible capacity of 613 mA h g -1 with 88% retention over 500 cycles. The exceptional stability is achieved by using a standard electrolyte (1 M NaClO4 EC-DMC) without secondary additives or high salt concentrations. The rate capability is also superb, achieving 300 mA h g -1 at 10C. Compared to recent state-of-the-art literature, the Se-CCN is the most cyclically stable and offers the highest rate performance. As a Se–Na battery, the system achieves 992 W h kg -1 at 68 W kg -1 and 384 W h kg -1 at 10144 W kg -1 (by active mass in a cathode). We are the first to fabricate and test a Se-based full NIB, which is based on Se-CCN coupled to a Na intercalating pseudographitic carbon (PGC) anode. It is demonstrated that the PGC anode increases its structural order in addition to dilating as a result of Na intercalation at voltages below 0.2 V vs. Na/Na+. The {110} Na reflections are distinctly absent from the XRD patterns of PGC sodiated down to 0.001 V, indicating that the Na metal pore filling is not significant for pseudographitic carbons. Lastly, the battery delivers highly promising Ragone chart characteristics, for example yielding 203 and 50 W h kg -1 at 70 and 14 000 W kg -1 (via total material mass in the anode and cathode).

25 ENERGY STORAGE↗

The status of LILW disposal facility construction in Korea

In this paper, we discuss the experiences during the construction of the first LILW disposal facility in South Korea. In December 2005, the South Korean Government designated Gyeongju-city as a host city of Low- and Intermediate-Level Radioactive Waste(LILW) disposal site through local referendums held in regions whose local governments had applied to host disposal facility in accordance with the site selection procedures. The LILW disposal facility is being constructed in Bongilri, Yangbuk-myeon, Gyeongju. The official name of the disposal facility is called 'Wolsong Low and Intermediate Level Radioactive Waste Disposal Center (LILW Disposal Center)'. It can dispose of 800,000 drums of radioactive wastes in a site of 2,100,000 square meters. At the first stage, LILW repository of underground silo type with disposal capacity of 100,000 drums is under construction expected to be completed by June of 2014. The Wolsong Low and Intermediate Level Radioactive Waste Disposal Center consists of surface facilities and underground facilities. The surface facilities include a reception and inspection facility, an interim storage facility, a radioactive waste treatment building, and supporting facilities such as main control center, equipment and maintenance shop. The underground facilities consist of a construction tunnel for transport of construction equipment and materials, an operation tunnel for transport of radioactive waste, an entrance shaft for workers, and six silos for final disposal of radioactive waste. As of Dec. 2012, the overall project progress rate is 93.8%. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

A Bulk versus Nanoscale Hydrogen Storage Paradox Revealed by Material-System Co-Design

Metal hydrides are serious contenders for materials-based hydrogen storage to overcome constraints associated with compressed or liquefied H 2 . Their ultimate performance is usually evaluated using intrinsic material properties without considering a systems design perspective. An illustrative case with startling implications is (LiNH 2 +2LiH). Using models that simulate the storage system and associated fuel cell of a light-duty vehicle (LDV), the performance of the bulk hydrides is compared with a nanoscaled version in porous carbon (PC), (LiNH 2 +2LiH)@(6-nm PC). Using experimental material properties, the simulations show that (LiNH 2 +2LiH)@(6-nm PC) counterintuitively has higher usable gravimetric and volumetric capacities than the bulk counterpart on a system basis despite having lower capacities on a materials-only basis. Nanoscaling increases the thermal conductivity and lowers the desorption enthalpy, which consequently increases heat management efficiency. In a simulated drive cycle for fuel cell-powered LDV, the fuel cell is inoperable using bulk (LiNH 2 +2LiH) as the storage material but completes the drive cycle using the nanoscale material. Further, these results challenge the notion that nanoscaling incurs mass and volume penalties. Instead, the synergistic nanoporous host-hydride interaction can favorably modulate chemical and heat transfer properties. Moreover, a co-design approach considering application-specific tradeoffs is essential to accurately assess a material's potential for real-world hydrogen storage.

08 HYDROGEN↗

Constitutive Model Development for Aging Polymer Encapsulants (ASC P&EM FY2021 L2 Milestone 7836)

This SAND report fulfills the completion requirements for the ASC Physics and Engineering Modeling Level 2 Milestone 7836 during Fiscal Year 2021. The Sandia Simplified potential energy clock (SPEC) non-linear viscoelastic constitutive model was developed to predict a whole host of polymer glass physical behaviors in order to provide a tool to assess the effects of stress on these materials over their lifecycle. Polymer glasses are used extensively in applications such as electronics packaging, where encapsulants and adhesives can be critical to device performance. In this work, the focus is on assessing the performance of the model in predicting material evolution associated with long-term physical aging, an area that the model has not been fully vetted in. These predictions are key to utilizing models to help demonstrate electronics packaging component reliability over decades long service lives, a task that is very costly and time consuming to execute experimentally. The initiating hypothesis for the work was that a model calibration process can be defined that enables confidence in physical aging predictions under ND relevant environments and timescales without sacrificing other predictive capabilities. To test the hypothesis, an extensive suite of calibration and aging data was assembled from a combination of prior work and collaborating projects (Aging and Lifetimes as well as the DoD Joint Munitions Program) for two mission relevant epoxy encapsulants, 828DGEBA/DEA and 828DGEBA/T403. Multiple model calibration processes were developed and evaluated against the entire set of data for each material. A qualitative assessment of each calibration's ability to predict the wide range of aging responses was key to ranking the calibrations against each other. During this evaluation, predictions that were identified as non-physical, i.e., demonstrated something that was qualitatively different than known material behavior, were heavily weighted against the calibration performance. Thus, unphysical predictions for one aspect of aging response could generate a lower overall rating for a calibration process even if that process generated better quantitative predictions for another aspect of aging response. This insurance that all predictions are qualitatively correct is important to the overall aim of utilizing the model to predict residual stress evolution, which will depend on the interplay amongst the different material aging responses. The DSC-focused calibration procedure generated the best all-around aging predictions for both materials, demonstrating material models that can qualitatively predict the whole host of different physical aging responses that have been measured. This step forward in predictive capability comes from an unanticipated source, utilization of calorimetry measurements to specify model parameters. The DSC-focused calibration technique performed better than compression-focused techniques that more heavily weigh measurements more closely related to the structural responses to be predicted. Indeed, the DSC-focused calibration procedure was only possible due to recent incorporation of the enthalpy and heat capacity features into SPEC that was newly verified during this L2 milestone. Fundamentally similar aspects of the two material model calibrations as well as parametric studies to assess sensitives of the aging predictions are discussed within the report. A perspective on the next steps to the overall goal of residual stress evolution predictions under stockpile conditions closes the report.

36 MATERIALS SCIENCE↗

Deep Space Optical Communications

The future demand for enhanced telecommunication capacity required to support human and robotic exploration from deep-space has motivated the advancement of free-space laser communication technologies for the past few decades. Steady advances in these technologies, validated through space-to-ground demonstrations, have resulted in incremental advances with the deep-space optical communications (DSOC) technology demonstration being one of the next milestones on NASA’s roadmap. NASA’s Psyche Mission to launch early next decade plans to host a DSOC flight laser transceiver for link demonstrations extending from 0.1 to farther than 2 astronomical units (AU). The capabilities validated though this demonstration, we expect, could spur the use of optical communications infrastructure around Mars in the next few decades. In this paper we summarize ongoing activities underway at the Jet Propulsion Laboratory in preparation for the DSOC technology demonstration and go on to present discussions on the drivers for developing a robust deep space laser communications operational capability.

Hoppe, Daniel↗

Recent Developments at the U.S. Navy Wave Energy Test Site.

The U.S. Navy’s Wave Energy Test Site (WETS) in Hawaii has hosted two wave energy conversion (WEC) devices since its June 2015 commissioning – the Fred. Olsen BOLT Lifesaver and the Northwest Energy Innovations (NWEI) Azura – each for two deployments. Several additional devices will be tested in the coming years, beginning with the Ocean Energy device in summer 2019. The Hawaii Natural Energy Institute (HNEI) provides research and logistics support to WETS. We will provide an overview of three major activities that we have recently undertaken in this capacity. First, we will discuss results from a project in which modifications were made to the hull and float of the Azura, aimed at improving power performance for a second WETS deployment. Second, HNEI undertook a redeployment of Lifesaver beginning in October 2018, with the dual intent of achieving improvements in reliability and power performance, while also conducting an important demonstration of the use of wave power for non-grid applications. HNEI partnered with the University of Washington to integrate their Adaptable Monitoring Package (AMP) into the hull of BOLT Lifesaver. Included for this deployment was a subsea inductive charging capability from WiBotic, Inc.. These systems are powered entirely by electricity generated by the Lifesaver itself. Finally, HNEI has undertaken design improvements for the deeper berth moorings at WETS, with principal engineering guidance from DNV GL. This has included extensive numerical analysis of strength and fatigue aimed at establishing moorings that can persist for as long as possible. The resulting design will be discussed.

Wave energy conversion devices, Alternative market↗

The status of LILW disposal facility construction in Korea - 15158

In this paper, we discuss the experiences during the construction of the first LILW disposal facility in South Korea. In December 2005, the South Korean Government designated Gyeongju-city as a host city of Low- and Intermediate-Level Radioactive Waste (LILW) disposal site through local referendums held in regions whose local governments had applied to host disposal facility in accordance with the site selection procedures. The LILW disposal facility is being constructed in Bongil-ri, Yangbuk-myeon, Gyeongju. The official name of the disposal facility is called 'Wolsong Low and Intermediate Level Radioactive Waste Disposal Center (LILW Disposal Center)'. It can dispose of 800,000 drums of radioactive wastes in a site of 2,100,000 square meters. At the first stage, LILW repository of underground silo type with disposal capacity of 100,000 drums was completed by the end of June 2014. The Wolsong Low and Intermediate Level Radioactive Waste Disposal Center consists of surface facilities and underground facilities. The surface facilities include a receipt and inspection facility, an interim storage facility, a radioactive waste treatment building, and supporting facilities such as main control center, equipment and maintenance shop. The underground facilities consist of a construction tunnel for transport of construction equipment and materials, an operation tunnel for transport of radioactive waste, an access shaft for workers, and six silos for final disposal of radioactive waste. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Differences in the resistive and thermodynamic properties of the single crystalline chiral superconductor candidate SrPtAs

The locally noncentrosymmetric superconductor SrPtAs is proposed to host a topological chiral d-wave state, but experimental reports have been limited to polycrystalline samples. Here we report the synthesis of single crystalline SrPtAs grown from Pb flux. SrPtAs crystallizes in the hexagonal space group P⁢6 3 /mmc with lattice parameters a=4.2445⁢(4) Å and c=8.9513⁢(18) Å. Additionally, magnetic susceptibility and electrical resistivity measurements reveal a superconducting transition at T c ~2.2 K, in agreement with previous reports on polycrystalline samples. Surprisingly, heat capacity data show only a small bulk transition at 0.7 K. We discuss the possible origins of the discrepancy between the various measurements.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Transmitted virus fitness and host T cell responses collectively define divergent infection outcomes in two HIV-1 recipients

Control of virus replication in HIV-1 infection is critical to delaying disease progression. While cellular immune responses are a key determinant of control, relatively little is known about the contribution of the infecting virus to this process. To gain insight into this interplay between virus and host in viral control, we conducted a detailed analysis of two heterosexual HIV-1 subtype A transmission pairs in which female recipients sharing three HLA class I alleles exhibited contrasting clinical outcomes: R880F controlled virus replication while R463F experienced high viral loads and rapid disease progression. Near full-length single genome amplification defined the infecting transmitted/founder (T/F) virus proteome and subsequent sequence evolution over the first year of infection for both acutely infected recipients. T/F virus replicative capacities were compared in vitro , while the development of the earliest cellular immune response was defined using autologous virus sequence-based peptides. The R880F T/F virus replicated significantly slower in vitro than that transmitted to R463F. While neutralizing antibody responses were similar in both subjects, during acute infection R880F mounted a broad T cell response, the most dominant components of which targeted epitopes from which escape was limited. In contrast, the primary HIV-specific T cell response in R463F was focused on just two epitopes, one of which rapidly escaped. This comprehensive study highlights both the importance of the contribution of the lower replication capacity of the transmitted/founder virus and an associated induction of a broad primary HIV-specific T cell response, which was not undermined by rapid epitope escape, to long-term viral control in HIV-1 infection. It underscores the importance of the earliest CD8 T cell response targeting regions of the virus proteome that cannot mutate without a high fitness cost, further emphasizing the need for vaccines that elicit a breadth of T cell responses to conserved viral epitopes.

59 BASIC BIOLOGICAL SCIENCES↗

Multipurpose aircraft monitoring with a smart recorder

This paper describes a microprocessor-based flight recorder the 'Smart Recorder' - which was developed and installed on a King Air aircraft used for commercial charter service. The recorder is used as a research tool for developing monitoring strategies and processing algorithms to: (1) characterize the typical flight environment encountered by the host aircraft, (2) develop technology for automated engine trend monitoring, and (3) implement a crash recording capability. Initially the recorder was used as an adaptive data acquisition system, monitoring engine sensors and flight instruments and then modifying its data acquisition in response to the perceived aircraft situation. Data collected in this manner were stored in a removable bubble memory and subsequently analyzed in the laboratory. Later, on-board processing was implemented to better utilize the available storage capacity.

White, J. H.↗

Confinement of Iodine Molecules into Triple-Helical Chains within Robust Metal–Organic Frameworks

During nuclear waste disposal process, radioactive iodine as a fission product can be released. The widespread implementation of sustainable nuclear energy thus requires the development of efficient iodine stores that have simultaneously high capacity, stability and more importantly, storage density (and hence minimized system volume). Here, we report high I 2 adsorption in a series of robust porous metal–organic materials, MFM-300(M) (M = Al, Sc, Fe, In). MFM-300(Sc) exhibits fully reversible I 2 uptake of 1.54 g g –1 , and its structure remains completely unperturbed upon inclusion/removal of I 2 . Direct observation and quantification of the adsorption, binding domains and dynamics of guest I 2 molecules within these hosts have been achieved using XPS, TGA-MS, high resolution synchrotron X-ray diffraction, pair distribution function analysis, Raman, terahertz and neutron spectroscopy, coupled with density functional theory modeling. These complementary techniques reveal a comprehensive understanding of the host–I 2 and I 2 –I 2 binding interactions at a molecular level. The initial binding site of I 2 in MFM-300(Sc), I 2 I , is located near the bridging hydroxyl group of the [ScO 4 (OH) 2 ] moiety [I 2 I ···H–O = 2.263(9) Å] with an occupancy of 0.268. I 2 II is located interstitially between two phenyl rings of neighboring ligand molecules [I 2 II ···phenyl ring = 3.378(9) and 4.228(5) Å]. I 2 II is 4.565(2) Å from the hydroxyl group with an occupancy of 0.208. Significantly, at high I 2 loading an unprecedented self-aggregation of I 2 molecules into triple-helical chains within the confined nanovoids has been observed at crystallographic resolution, leading to a highly efficient packing of I 2 molecules with an exceptional I 2 storage density of 3.08 g cm –3 in MFM-300(Sc).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Advancement of Systems Designs and Key Engineering Technologies for Materials Based Hydrogen Storage

UTRC lead the development of the Simulink Framework model that enables a comparison of different hydrogen storage systems on a common basis. The Simulink Framework model was disseminated on the www.HSECoE.org website that is hosted by NREL. UTRC contributed to a better understanding of the safety aspects of the proposed hydrogen storage systems. UTRC also participated in the Failure Mode and Effect Analysis of both the chemical- and the adsorbent-based hydrogen storage system during Phase 2 of the Hydrogen Storage Engineering Center of Excellence. UTRC designed a hydrogen storage system with a reversible metal hydride material in a compacted form for light-duty vehicles with a 5.6 kg H2 storage capacity, giving it a 300 miles range. It contains a heat exchanger that enables efficient cooling of the metal hydride material during hydrogen absorption in order to meet the 3.3 minute refueling time target. It has been shown through computation that the kinetics of hydrogen absorption of Ti-catalyzed NaAlH4 was ultimately limiting the rate of hydrogen absorption to 85% of the material capacity in 3.3 minutes. An inverse analysis was performed in order to determine the material property requirements in order for a metal hydride based hydrogen storage system to meet the DOE targets. Work on metal hydride storage systems was halted after the Phase 1 to Phase 2 review due to the lack of metal hydride materials with the required material properties. UTRC contributed to the design of a chemical hydrogen storage system by developing an adsorbent for removing the impurity ammonia from the hydrogen gas, by developing a system to meter the transport of Ammonia Borane (AB) powder to a thermolysis reactor, and by developing a gas-liquid-separator (GLS) for the separation of hydrogen gas from AB slurry in silicone oil. Stripping impurities from hydrogen gas is essential for a long life of the fuel cell system on board of a vehicle. Work on solid transport of AB was halted after the Phase 1 to Phase 2 review in favor of studying the slurry-form of AB as it appeared to be difficult to transport a solid form of AB through the thermolysis reactor. UTRC demonstrated the operation of a compact GLS in the laboratory at a scale that would be required for the actual automotive application. The GLS met the targets for weight and volume. UTRC also reported about the unresolved issue associated with the high vapor pressure of fluids that could be used for making a slurry-form of AB. Work on the GLS was halted after the Phase 2 to Phase 3 review as the off-board regeneration efficiency of the spent AB was below the DOE target of 60%. UTRC contributed to the design of an adsorbent-based hydrogen storage system through measurements of the thermal conductivity of a compacted form of Metal Organic Framework (MOF) number 5 and through the development and sizing of a particulate filter. Thermal conductivity is important for the design of the modular adsorbent tank insert (MATI), as developed by Oregon State University (OSU), in order to enable a rapid refueling process. Stringent hydrogen quality requirements can only be met with an efficient particulate filtration system. UTRC developed a method to size the particulate filter by taking into account the effect of the pressure drop on the hydrogen adsorption process in the tank. UTRC raised awareness about the potential use of materials-based H2 storage systems in applications outside the traditional light-duty vehicle market segment by presenting at several conferences about niche application opportunities in Unmanned Aerial Vehicles (UAV), Autonomous Underwater Vehicles (AUV), portable power and others.

08 HYDROGEN↗

Host Design for Carbon Capture and Regeneration in Porous Liquids

The demand for efficient gas capture technologies drives the exploration of porous liquids (PLs) as alternatives to traditional amine mixtures, which incur high operational costs due to energy-intensive regeneration processes. This research investigates the use of porous organic cages (POCs) within PLs to enhance gas capture and separation capabilities. We demonstrate that the flexibility of POCs under isostatic pressure facilitates the expulsion of captured gas molecules, enabling low-energy regeneration and the creation of an isostatic pressure testing capability for PLs. Additionally, a new CC3-OH POC derivative with scrambled hydroxides exhibits a twofold increase in CO 2 adsorption capacity, attributed to enhanced interactions between hydroxide linkers and CO 2 . Furthermore, we explore the stability of azobenzene-containing organic cages formed via imine and amine bonds, revealing that the flexible amine bond allows for more efficient E-Z isomerization. Our findings highlight the transformative potential of PLs and azobenzene-derived systems in gas separation technologies, paving the way for innovative low-energy regeneration pathways.

36 MATERIALS SCIENCE↗

Electrochemistry in the Large Tunnels of Lithium Postspinel Compounds

Lithium spinels (Li MM 'O 4 ) are an important class of mixed-cation materials that have found uses in batteries, catalysis, and optics. Postspinels are a series of related framework structures with the AMM 'O 4 host composition that are formed with larger A -site cations, typically under high pressure. Postspinels have one-dimensional tunnel structures with pores that are larger than those in spinel and triangular in cross-section, but they are relatively unexplored as intercalation electrodes. While lithium postspinels have been previously found to be thermodynamically stable only at high pressures, we have identified a synthetic pathway that produces the lithium-containing materials at ambient pressure using an ion-exchange process from the corresponding sodium postspinels. Here, in this work, we report the synthesis and a survey of the electrochemical properties of 10 new lithium CaFe 2 O 4 -type postspinel compounds where M = Mn 3+ , V 3+ , Cr 3+ , Rh 3+ , Fe 2+ , Mg 2+ , Co 2+ and M ' = Ti 4+ and/or Sn 4+ . Although complete delithiation is not achieved during electrochemical cycling, many of the lithium postspinels have substantial charge storage capacity in Li battery cells owing to the ability of the large framework tunnels to accommodate more than one lithium ion per formula unit. Multiple redox couples are accessed for LiMnSnO 4 , Li 0.96 Mn 0.96 Sn 1.04-x Ti x O 4 , Li 0.96 V 0.96 Ti 1.04 O 4 , Li 0.96 Cr 0.96 Ti 1.04 O 4 , and LiFe 0.5 Ti 1.5 O 4 . Compositions with moderate or poor lithium cyclability are also discussed for comparison. Redox mechanisms and trends are identified by comparing this new redox-active framework to related spinels, ramsdellites, and 'Na 0.44 MnO 2 ' structures, and from density functional theory (DFT) electronic structures. Operando diffraction shows complex structural responses to lithium insertion and extraction in this postspinel framework. A DFT framework was proposed to identify promising lithium postspinel phases that could be accessed metastably under ambient pressure conditions and to assess their stability to lithium insertion and extraction. This work suggests that CaFe 2 O 4 -type hosts are a promising new class of lithium-ion energy storage materials.

25 ENERGY STORAGE↗

A Lithium-Sulfur Cell Based on Reversible Lithium Deposition from a Li 2 S Cathode Host onto a Hostless-Anode Substrate

Here, the development of lithium–sulfur batteries necessitates a thorough understanding of the lithium-deposition process. A novel full-cell configuration comprising an Li 2 S cathode and a bare copper foil on the anode side is presented here. The absence of excess lithium allows for the realization of a truly lithium-limited Li–S battery, which operates by reversible plating and stripping of lithium on the hostless-anode substrate (copper foil). Its performance is closely tied to the efficiency of lithium deposition, generating valuable insights on the role and dynamic behavior of lithium anode. The Li 2 S full cell shows reasonable capacity retention with a Coulombic efficiency of 96% over 100 cycles, which is a tremendous improvement over that of a similar lithium-plating-based full cell with LiFePO 4 cathodes. The exceptional robustness of the Li 2 S system is attributed to an intrinsic stabilization of the lithium-deposition process, which is mediated by polysulfide intermediates that form protective Li 2 S and Li 2 S 2 regions on the deposited lithium. Combined with the large improvements in energy density and safety by the elimination of a metallic lithium anode, the stability and electrochemical performance of the lithium-plating-based Li 2 S full cell establish it as an important trajectory for Li–S battery research, focusing on practical realization of reversible lithium anodes.

25 ENERGY STORAGE↗