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At least 253 records · Page 14

De-risking fault leakage risk and containment integrity for subsurface storage applications

The subsurface is pivotal in the energy transition, for the sequestration of CO 2 and energy storage. It is crucial to understand to what extent geological faults may form leakage pathways that threaten the containment integrity of these projects. Fault flow behavior has been studied in the context of hydrocarbon development, supported by observations from wells drilled through faults, but such observations are rare in geoenergy projects. Focusing on mechanical behavior as early indicator of potential leakage risks, a probabilistic Coulomb Failure Stress workflow is developed and demonstrated using data from the Decatur CO 2 sequestration project to rank faults based on their containment risk. The analysis emphasizes the importance of fault throw relative to reservoir thickness and pore pressure change in assessing reactivation risks. Integrating this mechanical assessment with geological and dynamic fault analyses contributes to derisking fault containment for geoenergy applications, providing valuable insights for the successful development of subsurface storage projects.

58 GEOSCIENCES↗

Toward sustainable production of N-containing products via nonthermal plasma-enhanced conversion of natural gas resources

Nonthermal plasmas can directly activate and cleave the strong chemical bonds in molecular nitrogen and methane to facilitate the transformation of these inherently stable molecules through the application of electrical energy. Here, we report a low temperature, atmospheric pressure, nonthermal plasma for the “one-pot” synthesis of olefins, alkynes, higher molecular weight hydrocarbons, ammonia, and nitrogen-containing liquids from a representative shale gas feed enriched with nitrogen. Furthermore, we reproducibly observe a wide range of valuable and synthetically challenging gas-phase and liquid-phase products containing C-N, C-C, and N-H bonding by controlling the N 2 concentration in the inlet feed stream. In nitrogen-lean regimes, hydrocarbon products dominate (e.g., ethylene, acetylene, etc.), while nitrogen-rich regimes promote incorporation of nitrogen into the products, leading to the formation of ammonia and liquid products containing a variety of functionalities (e.g., nitriles, amines, heterocycles). High resolution electrospray ionization mass spectrometry was used to measure molecular weights and identify the chemical formulas of the liquid products. Van Krevelen diagrams were created and showed many products with compositions around H/C = 2 and N/C = 0.5, indicating the potential importance of intermediate species with these ratios for liquid formation (e.g., CH 3 CN + H).

03 NATURAL GAS↗

Microbial interactions with phosphorus containing glasses representative of vitrified radioactive waste

The presence of phosphorous in borosilicate glass (at 0.1 – 1.3 mol % P 2 O 5 ) and in iron-phosphate glass (at 53 mol % P 2 O 5 ) stimulated the growth and metabolic activity of anaerobic bacteria in model systems. Dissolution of these phosphorous containing glasses was either inhibited or accelerated by microbial metabolic activity, depending on the solution chemistry and the glass composition. The breakdown of organic carbon to volatile fatty acids increased glass dissolution. The interaction of microbially reduced Fe(II) with phosphorus-containing glass under anoxic conditions decreased dissolution rates, whereas the interaction of Fe(III) with phosphorous-containing glass under oxic conditions increased glass dissolution. Phosphorous addition to borosilicate glasses did not significantly affect the microbial species present, however, the diversity of the microbial community was enhanced on the surface of the iron phosphate glass. Results demonstrate the potential for microbes to influence the geochemistry of radioactive waste disposal environments with implication for wasteform durability.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

Effects of Composition and Oxidation States on the Structures of Chromium-Containing Sodium Silicate Glasses: Molecular Dynamics Simulations using Machine Learning Interatomic Potentials

Chromium represents a significant challenge for the vitrification of high-level nuclear waste into silicate and borosilicate glasses due to its low solubility and variable oxidation states, which can limit the waste loading due to promotion of crystallization or phase separation during processing. In this study, we modeled chromium containing silicate glasses using molecular dynamics simulations with three machine learning interatomic potentials (MLIPs), MACE, CHGNet, and PFP were employed, to gain insights on glass composition and oxidation states on the structures of these glasses. One of the goals is to evaluate their ability of these MLIPs to accurately represent the general structure of silicate glasses and chromium local environments as a function of chromium oxidation states. Density Functional Theory (DFT) based calculations and experimental data such as neutron structure factors were used to validate the structural models. It was found that the foundation models of all three MLIPs are able to reproduce general structural features of the sodium silicate glass structure consistent with experimental and DFT data, but only CHGNet and PFP can accurately capture the oxidation states and local environment of chromium: tetrahedral for Cr6+ and octahedral for Cr3+. Furthermore, we studied the effect of varying Cr3+/ Cr6+ (Cr3+/Crtotal) ratio and total chromium content using PFP. Our results show that Cr6+ enhances network polymerization by reducing non-bridging oxygens through Na? charge compensation required due to the formation of chromate (CrO42-) species, while Cr³? acts as a network modifier that disrupts connectivity. System size effects on the structural characteristics and chromium environments were also tested using the PFP potential. This work highlights the importance of careful validation on the precision, transferability, and potential of MLIPs for modeling glasses containing transition metal elements that can exist in multiple oxidation states. It is also encouraging to see the foundational models are all three MLFFs are able to reproduce the basic sodium silicate glass structures, while suggesting additional training or refining is needed to improve the description of more complex systems containing transition metals.

Puga, Christina L.↗

Structural and spectroscopic characterization of photoactive yellow protein and photoswitchable fluorescent protein constructs containing heavy atoms

Photo-induced structural rearrangements of chromophore-containing proteins are essential for various light-dependent signaling pathways and optogenetic applications. Ultrafast structural and spectroscopic methods have offered insights into these structural rearrangements across many timescales. However, questions still remain about exact mechanistic details, especially regarding photoisomerization of the chromophore within these proteins femtoseconds to picoseconds after photoexcitation. Instrumentation advancements for time-resolved crystallography and ultrafast electron diffraction provide a promising opportunity to study these reactions, but achieving enough signal-to-noise is a constant challenge. In this work, we present four new photoactive yellow protein constructs and one new fluorescent protein construct that contain heavy atoms either within or around the chromophore and can be expressed with high yields. Structural characterization of these constructs, most at atomic resolution, show minimal perturbation caused by the heavy atoms compared to wild-type structures. Spectroscopic studies report the effects of the heavy atom identity and location on the chromophore’s photophysical properties. None of the substitutions prevent photoisomerization, although certain rates within the photocycle may be affected. Overall, these new proteins containing heavy atoms are ideal samples for state-of-the-art time-resolved crystallography and electron diffraction experiments to elucidate crucial mechanistic information of photoisomerization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Air-stable, earth-abundant molten chlorides and corrosion-resistant containment for chemically-robust, high-temperature thermal energy storage for concentrated solar power

A dramatic reduction in man-made CO 2 emissions could be achieved if the cost of electricity generated from concentrated solar power (CSP) plants could become competitive with fossil-fuel-derived electricity. The solar heat-to-electricity conversion efficiency of CSP plants may be significantly increased (and the associated electricity cost decreased) by operating CSP turbines with inlet temperatures ≥750 °C instead of ≤550 °C, and by using thermal energy storage (TES) at ≥750 °C to allow for rapidly dispatchable and/or continuous electricity production. Unfortunately, earth-abundant MgCl 2 -KCl-based liquids currently being considered as low-cost media for large-scale, high-temperature TES are susceptible to oxidation in ambient air, with associated undesired changes in liquid composition and enhanced corrosion of metal alloys in pipes and tanks containing such liquids. In this paper, alternative high-temperature, earth-abundant molten chlorides that are resistant to oxidation in ambient air are identified via thermodynamic calculations. Here, the oxidation resistance, and corrosion-resistant containment, of such molten chlorides at 750 °C are then demonstrated. Such an air-tolerant strategy, involving chemically-robust, low-cost TES media paired with effective containment materials, provides a critical advance towards the higher-temperature operation of, and lower-cost electricity generation from, CSP plants.

14 SOLAR ENERGY↗

Mixtures of CO 2 and poly(fluoroacrylate) based on monomers containing only six or four fluorinated carbons: Phase behavior and solution viscosity

In this study, homopolymerization of fluoroacrylate monomers containing a segment with eight fluorinated carbons, (CH 2 CHCOO(CH 2 ) 2 (CF 2 ) 7 CF 3 ), yield poly(fluoroacrylate) (PFA) with remarkably high solubility in CO 2 , but the corresponding ultimate PFA degradation product perfluorooctanoic acid (PFOA) is bio-accumulative. Based on cloud point loci in the 1–4 wt% PFA in CO 2 concentration range at temperatures of 25, 50, 75, 100 and 125°C, it is shown that C 6 F 13 -based and C 4 F 9 -based PFA, with relatively benign degradation products perfluorohexanoic acid (PFHxA) and perfluorobutanoic acid (PFBA), respectively, retain the same level of CO 2 -solubility as that of C 8 F 17 -based PFA. Further, both C 6 F 13 -based and C 4 F 9 -based PFA can increase the viscosity of single-phase CO 2 -PFA solutions (i.e. thicken CO 2 ) as much as C 8 F 17 -based PFA in the 25–125°C range. Therefore, the design of CO 2 -soluble PFA need not be constrained to monomers containing the C 8 F 17 moiety; fluoroacrylate monomers containing shorter fluoroalkyl segments with only four or six fluorocarbons can be utilized.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Molecular Catalysts with Diphosphine Ligands Containing Pendant Amines

Pendant amines play an invaluable role in chemical reactivity, especially for molecular catalysts based on Earth-abundant metals. As inspired by [FeFe]-hydrogenases, which contain a pendant amine positioned for cooperative bifunctionality, synthetic catalysts have been developed to emulate this multifunctionality through incorporation of a pendant amine in the second coordination sphere. Cyclic diphosphine ligands containing two amines serve as the basis for a class of catalysts that have been extensively studied and used to demonstrate the impact of a pendant base. These 1,5-diaza-3,7-diphosphacyclooctanes, now often referred to as “P 2 N 2 ” ligands, have profound effects on the reactivity of many catalysts. The resulting [Ni(P R 2 N R ´ 2 ) 2 ] 2+ complexes are electrocatalysts for both the oxidation and production of H 2 . Achieving the optimal benefit of the pendant amine requires that it has suitable basicity and is properly positioned relative to the metal center. In addition to the catalytic efficacy demonstrated with [Ni(P R 2 N R ´ 2 )2] 2+ complexes for the oxidation and production of H2, catalysts with diphosphine ligands containing pendant amines have also be demonstrated for a variety of metals for many different reactions, both in solution and immobilized on surfaces. Here, the impact of pendant amines in catalyst design has been demonstrated and continues to expand.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Expanded View of NMR Spin–Lattice Relaxation in Fluorine-Containing Ionic Liquids

Fluorine-containing anions are widely used in ionic liquids due to their unique physicochemical properties. However, the local dynamics of both cations and anions and their associated relaxation mechanisms remain incompletely understood. Here, we present a 1 H and 19 F spin–lattice relaxation rate (R1) study as a function of frequency over a broad frequency range from 30 kHz to 800 MHz for ionic liquids containing BF 4 – , PF 6 – , TFSI – , and FSI – anions and EMIM + cation. By combining experimental R 1 H and R 1 F NMR dispersion (NMRD) profiles with relaxation models for both dipolar spin interactions and chemical shift anisotropy (CSA) contributions, we demonstrate that CSA is needed to accurately describe the R 1 F relaxation behavior above ∼300 MHz, the extent of which depends on the anion structure. These findings challenge the long-standing assumption that dipolar contribution is the main source of 19 F relaxation in these systems and highlight the importance of including CSA to accurately interpret 19 F relaxation in ionic liquids, particularly at high frequencies. This work provides new insights into the molecular dynamics of fluorine-containing species.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Regio- and Enantioselective Bromocyclization of Difluoroalkenes as a Strategy to Access Tetrasubstituted Difluoromethylene-Containing Stereocenters

Difluoromethylene-containing compounds have attracted substantial research interest over the past decades for their ability to mimic biological functions of traditional functional groups while providing a wide variety of pharmacological benefits bestowed by the C–F bond. Here, we report a novel strategy to access RCF 2 Br-containing heterocycles by regio- and enantioselective bromocyclization of difluoroalkenes enabled by chiral anion phase-transfer catalysis. The utility of this methodology was highlighted through a synthesis of an analogue of efavirenz, a drug used for treating HIV. Additionally, the synthetic versatility of the CF 2 Br intermediates was showcased through functionalization to a variety of enantioenriched α,α-difluoromethylene-containing products.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Investigation of Americium-Containing Phosphates, Silicates, Borates, Molybdates, and Fluorides Synthesized via High-Temperature Flux Crystal Growth

The crystal chemistry of americium-containing extended structures was investigated, and several classes of americium-containing solid-state oxide materials were obtained in single-crystal form via high-temperature flux crystal growth. This enabled the structural characterization of rare examples of ternary, quaternary, and penternary americium-containing silicates K 3 Am (Si 2 O 7 ) and Cs 6 Am 2 Si 21 O 48 , phosphates Na 3 Am (PO 4 ) 2 and K 3 Am (PO 4 ) 2 , borates Ba 3 Am 2 (BO 3 ) 4 and AmBO 3 , borate halides Ca 5 Am(BO 3 ) 4 Cl, molybdates Li 0.5 Am 0.5 MoO 4 , and fluorides CsAm 2 F 7 . Using these crystallographic data, the ionic radii of Am 3+ with coordination numbers of six (0.975 Å), seven (1.052 Å), and nine (1.162 Å) were established. A maximum entropy method (MEM) analysis was performed on the single-crystal X-ray diffraction data that were collected for K 3 Nd(PO 4 ) 2 /K 3 Am(PO 4 ) 2 , K 3 NdSi 2 O 7 /K 3 AmSi 2 O 7 , and NdBO 3 /AmBO 3 , to qualitatively compare the ionicities of the Nd–O and Am–O bonds. In conclusion, Raman spectroscopy data were collected on single crystals of K 3 Am(PO 4 ) 2 and compared to the calculated Raman spectrum of K 3 Am(PO 4 ) 2 obtained from DFT calculations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Formation and optical properties of IR photoluminescence centres in bismuth-containing aluminophosphate glass

We have prepared aluminophosphate glass samples differing in bismuth oxide content and demonstrating broadband near-IR photoluminescence. Analysis of their photoluminescence spectra leads us to conclude that they contain two main types of emission centres, one of which seems to be a bismuth monocation and the other is a cluster ion. In addition to these luminescence centres, the aluminophosphate glasses contain a nonluminescent bismuth-containing centre responsible for the broad, strong optical absorption band peaking at 450 nm. (active media)

36 MATERIALS SCIENCE↗

Containers for Massive Ensemble of I/O Bound Hierarchical Coupled Simulations

We present our experience using containers to scale up a massive ensemble of coupled I/O bound workloads on the NERSC Cori supercomputer. We describe the design of a hierarchical simulation structure using the Integrated Plasma Simulator (IPS) that enables the flexible execution of coupled simulations at the system, node, and core level using the same coupling abstraction and API. The hierarchical design allows for the node-level execution to be efficiently executed using containers while not impacting the structure of the simulation at the system level. We demonstrate the viability of the approach by presenting experimental results from applications in coupled fusion plasma simulations that illustrate the performance impact of using containers to deploy the node-level workloads, in conjunction with the user mountable XFS file systems to ameliorate the load on the Lustre parallel file system. We also present results from production runs showing the ability of the ensemble simulations to scale to hundreds of Cori Haswell nodes, with little or no overhead.

Elwasif, Wael↗

Fabrication, Modeling, and Testing of a Prototype for Particle Thermal Energy Storage Containment

Increasing penetration of variable renewable energy resources requires the deployment of energy storage at a range of durations. Long-duration energy storage (LDES) technologies will fulfill the need to firm variable renewable energy resource output throughout the year. Conventional electrochemical batteries (e.g., lithium-ion) are uneconomical in this role due to high energy capacity costs. Thermal energy storage (TES) is one promising technology for LDES applications because of its siting flexibility and ease of scaling. Particle-based TES systems use low-cost solid particles that have higher temperature limits than the molten salts used in traditional concentrated solar power systems. A key component in particle-based TES systems is the containment silo for the high-temperature (> 1100 degrees C) particles. This study combined experimental testing and computational modeling methods to design and characterize the performance of a particle containment silo for LDES applications. A containment silo prototype was built at a laboratory scale and used to validate a congruent transient finite element analysis (FEA) model. The validation compared the actual and predicted temperature profile through the prototype over six days as the particles cooled from their initial temperature. The performance of a commercial scale (> 5 GWhth) was then characterized using the validated model. The transient FEA model was subject to several charge-discharge cycles to mimic a possible operating schedule. The commercial-scale model predicted a storage efficiency in excess of 95% after five days of storage with a design storage temperature of 1200 degrees C. Insulation material and concrete temperature limits were considered as well. The validation of the methodology means the FEA model can simulate a range of scenarios for future applications. This work supports the development of a promising LDES technology with implications for grid-scale electrical energy storage, but also for thermal energy storage for industrial process heating applications.

ENERGY STORAGE↗

The ChiS-Family DNA-Binding Domain Contains a Cryptic Helix-Turn-Helix Variant

Sequence-specific DNA-binding domains (DBDs) are conserved in all domains of life. These proteins carry out a variety of cellular functions, and there are a number of distinct structural domains already described that allow for sequence-specific DNA binding, including the ubiquitous helix-turn-helix (HTH) domain. In the facultative pathogen Vibrio cholerae, the chitin sensor ChiS is a transcriptional regulator that is critical for the survival of this organism in its marine reservoir. We recently showed that ChiS contains a cryptic DBD in its C terminus. This domain is not homologous to any known DBD, but it is a conserved domain present in other bacterial proteins. Here, we present the crystal structure of the ChiS DBD at a resolution of 1.28 Å. We find that the ChiS DBD contains an HTH domain that is structurally similar to those found in other DNA-binding proteins, like the LacI repressor. However, one striking difference observed in the ChiS DBD is that the canonical tight turn of the HTH is replaced with an insertion containing a β-sheet, a variant which we term the helix-sheet-helix. Through systematic mutagenesis of all positively charged residues within the ChiS DBD, we show that residues within and proximal to the ChiS helix-sheet-helix are critical for DNA binding. Finally, through phylogenetic analyses we show that the ChiS DBD is found in diverse proteobacterial proteins that exhibit distinct domain architectures. Together, these results suggest that the structure described here represents the prototypical member of the ChiS-family of DBDs.

59 BASIC BIOLOGICAL SCIENCES↗

InverseBench: Inverse design benchmark suite that contains inverse problems from science and engineering (InverseBench) v0.0.1

A software package that contains three inverse design blackbox problems to investigate the efficiency and accuracy of inverse design machine learning models. The software contains highly accurate forward machine learning models that can be used to assess the inverse predictions. The package also contains separate test data for each problem. The inverse design problems that are in the package are: airfoil inverse design, scalar boundary reconstruction and photonic surfaces inverse design.

Grbcic, Luka [Lawrence Berkeley National Laborator↗

Methane Activation on Cu Containing Zeolite Catalysts (Final Report)

In order to increase the value of the light alkane ethane found in shale gas, we investigated the transformation of ethane into ethylene and aromatic hydrocarbons using zinc-containing microporous catalysts. We investigated the kinetics of the reaction, and identified various active sites for the ethane dehydrogenation and aromatization. In addition, we investigated iron-containing zeolites, as catalysts for the addition of methyl groups to small olefins containing 2, 3 and 4 carbon molecules. We determined the reaction mechanism, the identity of the active site, and details of the reaction kinetics. We concluded that the use of iron zeolites is very promising to upgrade small olefins (2-4 carbon species) into larger olefins (4-7 carbon species) that are more valuable as fuels and as petrochemical products.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

3013 Inner Container Closure Weld Region (ICCWR) Characterization by Wide Area 3D Measurement System (WAMS) Analysis (FY21 Progress Report)

As part of the 3013 Surveillance Program, through-wall penetration from stress corrosion cracking (SCC) of the 3013 inner containers has been identified as the most credible condition for failure withing the 50- years lifetime. Chlorides contained in Pu-bearing material, together with intra-canister humidity levels, metallurgical conditions, and internal stresses have been found to produce corrosion in the Inner Container Closure Weld Region (ICCWR) of the 3013 canister system. A Laser Confocal Microscope (LCM) is used as part of the 3013 Surveillance Program protocol to identify the prevalence of corrosion and corrosionrelated cracking in the ICCWR2. With the LCM, a close visual examination is made of the ICCWR surface along with measurements of corrosion-related features. LCM inspections produce immense amounts of image data that is time intensive to analyze. There is also a 9-year backlog of images, with approximately 49 canisters that must be evaluated. To expedite data analysis and reduce the amount of generated data, a Wide Area 3D Measurement System (WAMS) microscope has been added to the examination protocol. Although WAMS is a lower resolution microscope, small features of interest can be still identified. The advantage of collecting data for the full circumference using the WAMS is that it can take about 1/16 of the time needed with the LCM. Both systems offer capabilities that combined can be utilized to expedite the examination of the ICCWR. The WAMS is an efficient system for screening and identification of corrosion features while the LCM can be utilized to obtain higher resolution images areas identified by the WAMS. This report explains and justifies the data collection methods used with the WAMS. It includes a summary of the data generated by WAMS in FY21. The goals set for data collection in FY21 were met. A total of twenty-two DE’s were imaged, and analysis was carried out on eleven samples. The analyzed samples showed large numbers of potential cracks and pits distributed throughout the surfaces. Lastly, to explain the advantages of the WAMS, its capabilities were compared to those of a simpler microscope. Micrographs of the samples imaged in FY21 and those analyzed are included in the appendices.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗