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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Tritium species diffusion on and desorption from γ-LiAlO 2 (100) surface: A first-principles investigation

γ-LiAlO 2 enriched in the 6 Li isotope is a good candidate for tritium (T, 3 H) production in nuclear reactor. In this work, to better understand its 3 H production performance, first-principles calculations are performed to study the 3 H-related species diffusion on and desorption from the γ-LiAlO 2 (100) surface. For the diffusion process, we investigate the pathways and energy barriers for the T and OT diffusion on the pristine and defective γ-LiAlO 2 (100) surfaces. Our results reveal that the O and Li/Al atoms of the surface layer play important roles for T and OT diffusion, respectively. By comparing with its diffusion barrier in bulk γ-LiAlO 2 , the order of energy barrier for T diffusion is: bulk < surface < defective surface, which is reversed for OT diffusion. Space is the prime factor for OT diffusion, while diffusion-mediating atom instead of space becomes the key factor for T diffusion. For the desorption process, we investigate the 3 H-related species (T, OT, T 2 , and T 2 O) desorption from the γ-LiAlO 2 (100) surface. The desorption energies we obtained are so high that the desorption behavior of all the 3 H-related species is nearly prohibited. We expect the possible T 2 or T 2 O release from the large accumulation of 3 H atoms on the surface.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2020

Interfacial solvation and slow transport of hydrated excess protons in non-ionic reverse micelles

This work employs molecular dynamics simulations to investigate the solvation and transport properties of hydrated excess protons (with a hydronium-like core structure) in non-ionic Igepal CO-520 reverse micelles of various sizes in a non-polar solvent. Multiscale Reactive Molecular Dynamics (MS-RMD) simulations were used to describe vehicular and hopping diffusion during the proton transport process. As detailed herein, an excess proton shows a marked tendency to localize in the interfacial region of micellar water pools. Slow proton transport was observed which becomes faster with increasing micellar size. Further analysis reveals that the slow diffusion of an excess proton is a combined result of slow water diffusion and the low proton hopping rate. This study also confirms that a low proton hopping rate in reverse micelles stems from the interfacial solvation of hydrated excess protons and the immobilization of interfacial water. The low water density in the interfacial region makes it difficult to form a complete hydrogen bond network near the hydrated excess proton, and therefore locks in the orientation of hydrated proton cations. The immobilization of the interfacial water also slows the relaxation of the overall hydrogen bond network.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1998

Reverse Energy Cascade in Turbulent Weakly Ionized Plasmas

For systems far from equilibrium, the neglect of a role for viscous effects in turbulence may be generally inappropriate when the relaxation time for the molecular process approaches the local flow time (Orou et al. (1996)). Furthermore, for stationary collisional plasmas, the conventional Reynolds number is irrelevant under circumstances where the standard features of turbulence in ordinary gases are observed in the plasma (Johnson et al. (1987)). The current theoretical understanding of these turbulent phenomenon is particularly inadequate for turbulence associated with ionizing shock waves; generally speaking, thermodynamic, acoustic and pressure fluctuations are all seen as amplified across the shock wave followed by a dramatic decay (relaminarization) usually attributed to a lack of importance of viscosity in the turbulent regions. This decay would be accelerated when the flow speed is also reduced due to the importance usually given to the conventional Reynolds number (which is directly proportional to velocity) as a quality of turbulence index. However, evidence supporting this consensus is lacking. By contrast, recent evidence of vanishing triple correlations form De Silva et al. (1996) provides strong support for early theoretical speculation of inherently molecular effects in macroscopic turbulence in Tsuge (1974). This specifically suggests that the role of compressive effects ordinarily associated with the shock wave could be significantly muted by the existence of a strongly turbulent local environment. There is also more recent theoretical speculation (Frisch et al. (1984)) of an inherently and previously unsuspected non-dissipative nature to turbulence, with energy conservation being nurtured by reverse energy cascades in the turbulent fluctuation spectra. Furthermore, the role which might be played by fluctuations on quantum mechanical phenomena and variations in molecular parameters is completely unknown, especially of the sort which might be found in optical spectra. A determination of the role which changing turbulent parameters might play on optical signatures behind a reflected shock wave should therefore provide a useful tool for the evolution of theoretical models for turbulence.

Williams, Kyron↗
DOE OSTI2020

Reversible inhibition and reactivation of electron transfer in photosystem I

In photosystem I (PSI) complexes at room temperature light induced electron transfer can proceed down multiple protein-cofactor branches, and the process can be an order of magnitude faster on one branch compared to the other. One factor that might contribute to this branch asymmetry is a tryptophan amino acid at position 673 on the psaB protein. This amino acid is located between two of the pigments involved in electron transfer on the psaB protein branch. The corresponding residue on the psaA protein branch is a glycine amino acid. Microsecond time-resolved step-scan FTIR difference spectroscopy at 77 K has been used to study isolated PSI complexes from wild type and a mutant where the tryptophan residue was changed to phenylalanine. Photoaccumulated FTIR difference spectra indicate changes in the protein structure upon mutation. In the mutant we also find that the electron transfer processes is inhibited following long periods of repetitive flash illumination at room temperature. This is due to double protonation of the pigment involved in electron transfer. However, we show that we can restore electron transfer functionality by incubating the light-treated mutant PSI samples in the presence of newly added (not protonated) pigment.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

RAMSeS: Rapid Analysis of Mission Software Systems

Over the past few decades, software has become ubiquitous as it has been integrated into nearly every aspect of society, including household appliances, consumer electronics, industrial control systems, public utilities, government operations, and military systems. Consequently, many critical national security questions can no longer be answered convincingly without understanding software, including its purpose, its capabilities, its flaws, its communication, or how it processes and stores data. As software continues to become larger, more complex, and more widespread, our ability to answer important mission questions and reason about software in a timely way is falling behind. Today, to achieve such understanding of third-party software, we rely predominantly on the ability of reverse engineering experts to manually answer each particular mission question for every software system of interest. This approach often requires heroic human effort that nevertheless fails to meet current mission needs and will never scale to meet future needs. The result is an emerging crisis: a massive and expanding gap between the national security need to answer mission questions about software and our ability to do so. Sandia National Laboratories has established the Rapid Analysis of Mission Software Systems (RAMSeS) effort, a collaborative long-term effort aimed at dramatically improving our nation’s ability to answer mission questions about third-party software by growing an ecosystem of tools that augment the human reverse engineer through automation, interoperability, and reuse. Focusing on static analysis of binary programs, we are attempting to identify reusable software analysis components that advance our ability to reason about software, to automate useful aspects of the software analysis process, and to integrate new methodologies and capabilities into a working ecosystem of tools and experts. We aim to integrate existing tools where possible, adapt tools when modest modifications will enable them to interoperate, and implement missing capability when necessary. Although we do hope to automate a growing set of analysis tasks, we will approach this goal incrementally by assisting the human in an ever-widening range of tasks.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
NASA NTRS1997

Precision Casting via Advanced Simulation and Manufacturing

A two-year program was conducted to develop and commercially implement selected casting manufacturing technologies to enable significant reductions in the costs of castings, increase the complexity and dimensional accuracy of castings, and reduce the development times for delivery of high quality castings. The industry-led R&D project was cost shared with NASA's Aerospace Industry Technology Program (AITP). The Rocketdyne Division of Boeing North American, Inc. served as the team lead with participation from Lockheed Martin, Ford Motor Company, Howmet Corporation, PCC Airfoils, General Electric, UES, Inc., University of Alabama, Auburn University, Robinson, Inc., Aracor, and NASA-LeRC. The technical effort was organized into four distinct tasks. The accomplishments reported herein. Task 1.0 developed advanced simulation technology for core molding. Ford headed up this task. On this program, a specialized core machine was designed and built. Task 2.0 focused on intelligent process control for precision core molding. Howmet led this effort. The primary focus of these experimental efforts was to characterize the process parameters that have a strong impact on dimensional control issues of injection molded cores during their fabrication. Task 3.0 developed and applied rapid prototyping to produce near net shape castings. Rocketdyne was responsible for this task. CAD files were generated using reverse engineering, rapid prototype patterns were fabricated using SLS and SLA, and castings produced and evaluated. Task 4.0 was aimed at developing technology transfer. Rocketdyne coordinated this task. Casting related technology, explored and evaluated in the first three tasks of this program, was implemented into manufacturing processes.

Source record↗
DOE OSTI2020

Freestanding self-assembled sulfonated pentablock terpolymer membranes for high flux pervaporation desalination

Pervaporation desalination has several advantages over competing desalination technologies, most notably an ability to select for or against volatile organic compounds and the ability to process high salinity feeds at a low transmembrane pressure. Pervaporation has not been commercialized for desalination applications because of its energy intensity. However, emerging processes such as hydraulic fracturing produce high total dissolved solids (>30-45 g/L) byproduct streams that exceed the operational limits of traditional reverse osmosis and could be treated by pervaporation. Here, we demonstrate free-standing pervaporation membranes with excellent permeance and high salt removal based on a partially sulfonated pentablock terpolymer with the tradename Nexar™. Pervaporation membranes were easily cast from this material with desalination performances comparable or superior to commercially available membranes. We found that the polymer degree of sulfonation and casting solvent polarity had a significant impact on the membranes’ water uptake but only a modest impact on the pervaporation desalination performance. Membranes with a degree of sulfonation of 52% (2.0 meq g –1 IEC) and a casting solution composed of 50 wt% n-propanol and 50 wt% toluene achieved a water flux of 3.32 kg m -2 h -1 (permeance 135 kg m -2 h -1 bar -1 ) with 99.5% salt removal in pervaporation from a 32 g/L –1 sodium chloride feed solution at room temperature. We demonstrated that dense, non-porous NexarTM pervaporation membrane permeance and salt separation performance were superior to commercial pervaporation membranes and equivalent to commercial membrane distillation membranes, which have much larger pores. Here, this study demonstrates that commercially available sulfonated pentablock terpolymers are excellent membranes for pervaporation desalination because of their ease of casting and excellent performance.

42 ENGINEERING↗
DOE OSTI2025

Depolymerization as a Design Strategy: Depolymerization Etching of Polymerization-Induced Microphase Separations

Thermally triggered depolymerization has traditionally been viewed through the lens of sustainability and recycling, not as a constructive tool for materials design. Herein, we show that selective, thermally triggered depolymerization to gaseous monomer serves as a solvent-free strategy for generating porosity in nanostructured polymer materials, offering a means to bypass the mass transport limitations inherent in conventional solution-based etching. As a demonstration platform, we employed polymerization-induced microphase separation (PIMS) to generate disordered bicontinuous block copolymer structures with embedded depolymerizable domains. By incorporating a methacrylate block susceptible to thermal depolymerization within a cross-linked, depolymerization-resistant styrenic matrix, we developed a process we term depolymerization etching of polymerization-induced microphase separations (DEPIMS). This approach enables highly selective and efficient domain removal via reversion to monomer to produce mesoporous materials with high surface areas (>200 m 2 /g). Subsequent surface functionalization yielded mesoporous adsorbents with tunable uptake kinetics and among the highest dye adsorption capacities reported for PIMS-derived materials, demonstrating the adaptability of the DEPIMS platform for chemical separations. DEPIMS can also be extended to a gram-scale, one-pot approach to yield mesoporous materials with recoverable monomer in under 12 h. These findings reposition thermal depolymerization from a sustainability tool to a broadly enabling strategy for scalable, on-demand fabrication of functional nanostructured materials.

Depolymerization↗
DOE OSTI2023

Promising approaches for the assembly of the catalytically active, recombinant Desulfomicrobium baculatum hydrogenase with substitutions at the active site

Background: Hydrogenases (H2ases) are metalloenzymes capable of the reversible conversion of protons and electrons to molecular hydrogen. Exploiting the unique enzymatic activity of H2ases can lead to advancements in the process of biohydrogen evolution and green energy production. Results: Here we created of a functional, optimized operon for rapid and robust production of recombinant [NiFe] Desulfomicrobium baculatum hydrogenase (Dmb H2ase). The conversion of the [NiFeSe] Dmb H2ase to [NiFe] type was performed on genetic level by site-directed mutagenesis. The native dmb operon includes two structural H2ase genes, coding for large and small subunits, and an additional gene, encoding a specific maturase (protease) that is essential for the proper maturation of the enzyme. Dmb, like all H2ases, needs intricate bio-production machinery to incorporate its crucial inorganic ligands and cofactors. Strictly anaerobic, sulfate reducer D. baculatum bacteria are distinct, in terms of their biology, from E. coli. Thus, we introduced a series of alterations within the native dmb genes. As a result, more than 100 elements, further compiled into 32 operon variants, were constructed. The initial requirement for a specific maturase was omitted by the artificial truncation of the large Dmb subunit. The assembly of the produced H2ase subunit variants was investigated both, in vitro and in vivo. This approach resulted in 4 recombinant [NiFe] Dmb enzyme variants, capable of H 2 evolution. The aim of this study was to overcome the gene expression, protein biosynthesis, maturation and ligand loading bottlenecks for the easy, fast, and cost-effective delivery of recombinant [NiFe] H2ase, using a commonly available E. coli strains. Conclusion: The optimized genetic constructs together with the developed growth and purification procedures appear to be a promising platform for further studies toward fully-active and O 2 tolerant, recombinant [NiFeSe] Dmb H2ase, resembling the native Dmb enzyme. It could likely be achieved by selective cysteine to selenocysteine substitution within the active site of the [NiFe] Dmb variant.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Application of electron beam technology to decompose persistent emerging drinking water contaminants: poly- and perfluoroalkyl substances (PFAS) and 1,4 dioxane.

Fermi Research Alliance, LLC (FRA) operates Fermilab under contract with the U.S. Department of Energy and has patents on technologies and applications of a novel mobile electron beam accelerator. A high-power version of this mobile accelerator based on FRA-developed SRF technology is under development at Illinois Accelerator Research Center (IARC) and can enable several new applications that have significant commercial potential. One such application is the e-beam treatment of persistent emerging contaminants in drinking water. The contaminants of concern are poly- and perfluoroalklyl substances (PFAS) and 1,4-dioxine. Both PFAS and 1,4-D are highly resistant to degradation and are not effectively removed by conventional drinking water treatment systems. Existing technologies, such as granular activated carbon (GAC) filters and reverse osmosis (RO) systems do not decompose. The Center for Clean Water Technology (CCWT) at Stony Brook University (SBU) is in the process of identifying and testing effective technologies to remove PFAS and/or 1,4-D from drinking waters. se PFAS, but rather concentrate them either by adsorption (GAC) or membrane rejection (RO). The Center for Clean Water Technology (CCWT) at Stony Brook University (SBU) is in the process of identifying and testing effective technologies to remove PFAS and/or 1,4-D from drinking waters to demonstrate the full-scale application of novel water treatment technologies and is experienced in conducting research to understand treatment performance with a particular focus on 1,4-D and PFAS contamination.

43 PARTICLE ACCELERATORS↗
NASA NTRS1977

Wash water reclamation technology for advanced manned spacecraft

The results of an analytical study and assessment of state-of-the-art wash water reclamation technology for advanced manned spacecraft is presented. All non-phase-change unit operations, unit processes, and subsystems currently under development by NASA are considered. Included among these are: filtration, ultrafiltration, carbon adsorption, ion exchange, chemical pretreatment, reverse osmosis, hyperfiltration, and certain urea removal techniques. Performance data are given together with the projected weights and sizes of key components and subsystems. In the final assessment, a simple multifiltration approach consisting of surface-type cartridge filters, carbon adsorption and ion exchange resins receives the highest rating for six-man orbital missions of up to 10 years in duration.

Putnam, D. F.↗
DOE OSTI2022

Tree-inspired lignin microrods-based composite heterogeneous nanochannels for ion transport and osmotic energy harvesting

One of the key processes of tree lignification is that lignin penetrates into the cell wall and fills in the cell wall framework, thereby increasing the hardness and hydrophobic of the tree channels, which is beneficial to consolidate and support the tree cell wall and water transport. Inspired by this natural process, we demonstrated a lignin-based nanofluidic heterogeneous membrane that closely mimics the channels in tree, which can realize ion transport function and effectively capture reverse electrodialysis. The membrane was synthesized by heating dealkaline lignin and PVA at 200 °C and this formed fusiform microrods and a closed-packed membrane. Simultaneously, this membrane composited with anodized aluminum (AAO) channels membrane at 200 °C to form asymmetric heterogeneous nanochannels membrane, which can transport counter-ions and harvest osmotic energy. This membrane implements ion current rectification in 0.1 M KCl electrolyte solution at pH 3 due to the confinement of pores and opposite surface charges in lignin-based heterogeneous nanochannel. An output power density of 0.97 W m- 2 is obtained under a 50-fold salinity gradient, which can be further improved to 1.19 W m -2 by increasing the salinity gradient from 50-fold to 500-fold. Accordingly, this nanofluidic membranes were prepared by using lignin, the key component in tree, which not only mimicked a crucial process of the water and ionic transport process of channels in tree, but also had the prospect in the field of osmotic energy harvesting.

09 BIOMASS FUELS↗
NASA NTRS1981

Theoretical and lidar studies of the density response of the mesospheric sodium layer to gravity wave perturbations

The density response of atmospheric layers to gravity waves is developed in two forms, an exact solution and a perturbation series solution. The degree of nonlinearity in the layer density response is described by the series solution whereas the exact solution gives insight into the nature of the responses. Density perturbation in an atmospheric layer are shown to be substantially greater than the atmospheric density perturbation associated with the propagation of a gravity wave. Because of the density gradients present in atmospheric layers, interesting effects were observed such as a phase reversal in the linear layer response which occurs near the layer peak. Once the layer response is understood, the sodium layer can be used as a tracer of atmospheric wave motions. A two dimensional digital signal processing technique was developed. Both spatial and temporal filtering are utilized to enhance the resolution by decreasing shot noise by more han 10 dB. Many of the features associated with a layer density response to gravity waves were observed in high resolution density profiles of the mesospheric sodium layer. These include nonlinearities as well as the phase reversal in the linear layer response.

Shelton, J. D.↗
NASA NTRS1972

Atmospheric helium and geomagnetic field reversals.

The problem of the earth's helium budget is examined in the light of recent work on the interaction of the solar wind with nonmagnetic planets. It is proposed that the dominant mode of helium (He4) loss is ion pumping by the solar wind during geomagnetic field reversals, when the earth's magnetic field is very small. The interaction of the solar wind with the earth's upper atmosphere during such a period is found to involve the formation of a bow shock. The penetration altitude of the shock-heated solar plasma is calculated to be about 700 km, and ionization rates above this level are estimated for a cascade ionization (electron avalanche) process to average 10 to the 9th power ions/sq cm/sec. The calculated ionization rates and the capacity of the solar wind to remove ionized helium (He4) from the upper atmosphere during geomagnetic dipole reversals are sufficient to yield a secular equilibrium over geologic time scales. The upward transport of helium from the lower atmosphere under these conditions is found to be adequate to sustain the proposed loss rate.

Sheldon, W. R.↗
DOE OSTI2023

Reversible Switch in Charge Storage Enabled by Selective Ion Transport in Solid Electrolyte Interphase

Solid-electrolyte interphases (SEIs) in advanced rechargeable batteries ensure reversible electrode reactions at extreme potentials beyond the thermodynamic stability limits of electrolytes by insulating electrons while allowing working ions to transport. Such selective ion transport occurs naturally in biological cell membranes as a ubiquitous prerequisite of many life processes and a foundation of biodiversity. In addition, cell membranes can selectively open and close the ion channels in response to external stimuli (e.g., electrical, chemical, mechanical, thermal), giving rise to “gating” mechanisms that help manage intracellular reactions. We wondered whether the chemistry and structure of SEIs can mimic cell membranes, such that ion gating can be replicated. That is, can SEIs realize a reversible switching between two electrochemical behaviors, i.e., the ion intercalation chemistry of batteries and the ion adsorption of capacitors? Herein, we report such SEIs that result in thermally activated selective ion transport. The function of open/close gate switches is governed by the chemical and structural dynamics of SEIs under different thermal conditions, with precise behaviors as conducting and insulating interphases that enable battery and capacitive processes within a finite temperature window. Such an ion gating function is synergistically contributed by Arrhenius-activated ion transport and SEI dissolution/regrowth. Following the understanding of this new mechanism, we then develop an electrochemical method to heal the SEI layer in situ. As a result, the knowledge acquired in this work reveals the possibility of hitherto unknown biomimetic properties of SEIs, which will guide us to leverage such complexities to design better SEIs for future battery chemistries.

25 ENERGY STORAGE↗
DOE OSTI2023

Cost optimization of low-salt-rejection reverse osmosis

Low-salt-rejection reverse osmosis (LSRRO) is an emerging membrane-based desalination technology for concentrating brines with potentially lower energy consumption and cost than thermally driven processes. We assess the technoeconomic performance of LSRRO by using an optimization model that minimizes the levelized cost of water (LCOW). We develop detailed models for the RO module and other equipment using WaterTAP (Water treatment Technoeconomic Assessment Platform), an open-source simulation and optimization software for water treatment. We improve upon previous LSRRO cost optimization studies by optimizing the salt permeability for each stage, which has significant implications for technoeconomic performance. We present the cost-optimal design, operation, and performance for three cases: 35 g/L TDS feed at 70% recovery, 70 g/L at 55%, and 125 g/L at 35%. The cost-optimal LCOW and specific energy consumption (SEC) for these cases are 0.70, 1.89, and 7.41 $/m 3 and 3.9, 8.4, and 30.4 kWh/m 3 , respectively. For each case, we use sensitivity analyses to provide guidance on key factors that impact economic viability. We also present the cost-optimal LCOW and SEC for feed concentrations between 5 and 220 g/L TDS and recoveries between 30 and 90%. So, we compare LSRRO to other high-salinity desalination technologies and find that it may be cost-competitive below feed concentrations of 125 g/L.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Reversibly growing crosslinked polymers with programmable sizes and properties

Growth constitutes a powerful method to post-modulate materials’ structures and functions without compromising their mechanical performance for sustainable use, but the process is irreversible. To address this issue, we here report a growing-degrowing strategy that enables thermosetting materials to either absorb or release components for continuously changing their sizes, shapes, compositions, and a set of properties simultaneously. The strategy is based on the monomer-polymer equilibrium of networks in which supplying or removing small polymerizable components would drive the networks toward expansion or contraction. Using acid-catalyzed equilibration of siloxane as an example, we demonstrate that the size and mechanical properties of the resulting silicone materials can be significantly or finely tuned in both directions of growth and decomposition. The equilibration can be turned off to yield stable products or reactivated again. During the degrowing-growing circle, material structures are selectively varied either uniformly or heterogeneously, by the availability of fillers. Our strategy endows the materials with many appealing capabilities including environment adaptivity, self-healing, and switchability of surface morphologies, shapes, and optical properties. Since monomer-polymer equilibration exists in many polymers, we envision the expansion of the presented strategy to various systems for many applications.

36 MATERIALS SCIENCE↗