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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Engineering Caldicellulosiruptor bescii with Surface Layer Homology Domain-Linked Glycoside Hydrolases Improves Plant Biomass Solubilization

Caldicellulosiruptor species hold promise as microorganisms that can solubilize the carbohydrate portion of lignocellulose and subsequently convert fermentable sugars into bio-based chemicals and fuels. Members of the genus have surface layer (S-layer) homology domain-associated glycoside hydrolases (SLH-GHs) that mediate attachment to biomass as well as hydrolysis of carbohydrates. Caldicellulosiruptor bescii , the most studied member of the genus, has only one SLH-GH.

Biotechnology & Applied Microbiology↗
DOE OSTI2023

Linking water quality, fouling layer composition, and performance of reverse osmosis membranes

Fouling of polyamide membranes during reverse osmosis (RO) is a major challenge for adopting membrane technologies to treat highly contaminated waters, especially those containing organic foulants (e.g., natural organic matter (NOM), polysaccharides) and dominant cations (e.g., sodium, magnesium, calcium). Here, this work combines bench-scale membrane fouling experiments with detailed characterization of feedwater chemistry and fouling layer composition/morphology to reveal fundamental mechanisms of (in)organic fouling during RO. Divalent cations are shown to promote fouling by hydrophobic NOM containing aromatic and carboxyl groups, while NOM fouling in the presence of a monovalent cation, sodium, occurs by smaller fulvic acids containing larger fractions of carboxyl groups and other oxygen-rich moieties. Calcium-carboxyl bridging occurs in solution and near the membrane surface to induce NOM aggregation on nanometer length scales. In complex waters containing foulant mixtures, co-fouling by calcium-carboxyl bridging and CaCO 3 precipitation influence membrane performance at longer timeframes. However, the flux decline observed for the co-fouling mechanism was less significant than the sum of its parts, suggesting both synergistic and antagonistic fouling mechanisms should be considered in membrane design/operation. These results encourage the design of pretreatment processes to reduce concentrations of multivalent ions and hydrophobic NOM in RO feedwaters, and of membrane materials to limit attachment/deposition of aggregates to/on polyamide surfaces.

42 ENGINEERING↗
NASA NTRS1997

Scalable Wrap-Around Shuffle Exchange Network with Deflection Routing

The invention in one embodiment is a communication network including plural non-blocking crossbar nodes, first apparatus for connecting the nodes in a first layer of connecting links, and second apparatus for connecting links independent of the first layer, whereby each layer is connected to the other layer at each point of the nodes. Preferably, each one of the layers of connecting links corresponds to one recirculating network topology that closes in on itself.

Monacos, Steve P.↗
DOE OSTI2023

Pressure-Dependent Magnetic Properties of Quasi-2D Cr 2 Si 2 Te 6 and Mn 3 Si 2 Te 6

Recently, pressure has been used to induce structural and magnetic phase transitions in many layered quantum materials whose layers are linked by van der Waals forces. Materials with such weakly held layers allow for relatively easy manipulation of the superexchange mechanism, which can give rise to novel magnetic behavior. Here, using hydrostatic pressure as a disorderless means to manipulate the interlayer coupling, we applied pressure on two quasi-2D sister compounds, namely, Cr 2 Si 2 Te 6 (CST) and Mn 3 Si 2 Te 6 (MST), up to ~1 GPa. Magnetic property measurements with the application of pressure revealed that the ferromagnetic transition temperature decreases in CST, while the opposite occurs for the ferrimagnetic MST. In MST, magnetization decreases with the increase in pressure, and such a trend is not clearly observed within the pressure range studied for CST. The overall pressure effect on magnetic characteristics such as exchange couplings and magnetic anisotropy energies is also examined theoretically using density functional theory. Exchange coupling in MST is strongly frustrated, and the first nearest neighbor interaction is the most dominant of the components with the strongest pressure dependence. In CST, the exchange coupling parameters exhibit very little dependence on pressure. This combined experimental and theoretical work has the potential to expand to other relevant quantum materials.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Crystal structure of deracoxib, C 17 H 14 F 3 N 3 O 3 S

The crystal structure of deracoxib has been solved and refined using synchrotron X-ray powder diffraction data, and optimized using density functional theory techniques. Deracoxib crystallizes in space group Pbca (#61) with a = 9.68338(11), b = 9.50690(5), c = 38.2934(4) Å, V = 3525.25(3) Å 3 , and Z = 8. The molecules stack in layers parallel to the ab-plane. N–H∙∙∙O hydrogen bonds link the molecules along the b-axis, in chains with the graph set C1,1(4), as well as more-complex patterns. N–H∙∙∙N hydrogen bonds link the layers. The powder pattern has been submitted to ICDD for inclusion in the Powder Diffraction File™ (PDF®).

36 MATERIALS SCIENCE↗
DOE OSTI2025

Impact of Electromagnetic Fields on Gypsum and Silica Scaling in Reverse Osmosis

Electromagnetic field (EMF) is a cost-effective, simple, and energy-efficient method for scale control in reverse osmosis (RO) systems. However, its effects on gypsum and silica scaling, as well as the underlying mechanisms, remain poorly understood. This study systematically investigates the effects of EMF treatment on gypsum and silica scaling in RO systems, utilizing synthetic brackish water and natural RO concentrate (ROC) from a desalination facility. For gypsum, EMF changes the crystal morphology, resulting in the formation of a porous, less compact scaling layer. It is more readily removed through hydraulic flushing (HF), enhancing scaling reversibility and water recovery. In the case of silica scaling, EMF promotes homogeneous polymerization in the bulk solution, producing larger silica particles that inhibit the formation of a dense, cross-linked gel layer on the membrane surface, mitigating flux decline. This study thus demonstrates EMF’s effectiveness in controlling gypsum scaling in undersaturated feedwaters when combined with HF and in mitigating silica scaling under both HF and non-HF conditions for supersaturated feedwaters. These findings underscore EMF’s versatility as a nonchemical approach for scale control in RO desalination and show its substantial potential to enhance membrane performance and operational efficiency in real-world water treatment applications.

Du, Xuewei [New Mexico State University, Las Cruce↗
DOE OSTI2022

Novel Class of Rhenium Borides Based on Hexagonal Boron Networks Interconnected by Short B 2 Dumbbells

Transition metal borides are known due to their attractive mechanical, electronic, refractive, and other properties. A new class of rhenium borides was identified by synchrotron single-crystal X-ray diffraction experiments in laser-heated diamond anvil cells between 26 and 75 GPa. Recoverable to ambient conditions, compounds rhenium triboride (ReB 3 ) and rhenium tetraboride (ReB 4 ) consist of close-packed single layers of rhenium atoms alternating with boron networks built from puckered hexagonal layers, which link short bonded (~ 1.7 angstrom) axially oriented B 2 dumbbells. The short and incompressible Re-B and B-B bonds oriented along the hexagonal c-axis contribute to low axial compressibility comparable with the linear compressibility of diamond. Sub-millimeter samples of ReB 3 and ReB 4 were synthesized in a large-volume press at pressures as low as 33 GPa and used for material characterization. Crystals of both compounds are metallic and hard (Vickers hardness, H V = 34(3) GPa). Geometrical, crystal-chemical, and theoretical analysis considerations suggest that potential ReB x compounds with x > 4 can be based on the same principle of structural organization as in ReB 3 and ReB 4 and possess similar mechanical and electronic properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Solvent oligomerization pathways facilitated by electrolyte additives during solid-electrolyte interphase formation

The solid–electrolyte interphase (SEI) layer formation is known to play an important role in determining the lifetime of lithium-ion batteries. A thin, stable SEI layer is linked to overall improved battery performance and longevity, however, the factors and mechanisms that lead to optimal SEI morphology and composition are not well understood. Inclusion of electrolyte additives (fluoroethylene carbonate, FEC; and vinylene carbonate, VC) is often necessary for improving SEI characteristics. To understand how these electrolyte additives impact SEI formation, we employed molecular dynamics (MD) and density functional theory (DFT) simulations to study the reaction networks and oligomerization pathways, respectively, for three systems containing ethylene carbonate (EC), a lithium ion, and FEC or VC. MD simulations suggest radical oligomerization pathways analogous to traditional oligomerization with nucleophilic alkoxide species via SN1 reaction mechanisms. Both S N 1 and S N 2 mechanisms were studied for all three systems using DFT. Oligomerization reactions were studied with both a standard alkoxide species and a ring-opened EC radical as the nucleophiles and EC, FEC, and VC as the electrophiles. For all cases, FEC and VC exhibited lower free energy barriers and more stable adducts when compared with EC. We conclude that one of the role of additives is to modify the oligomerization process of EC by introducing branching points (FEC) or termination points (VC).

25 ENERGY STORAGE↗
NASA NTRS2006

Steps Towards the Standardization of a More Efficient Uplink Protocol and Code

In June 2004, NASA announced a new vision for the further exploration of the Moon and Mars. The vision includes a long-term human and robotic program to explore the solar system, starting with a return to the Moon that will ultimately enable future exploration of Mars and other destinations. Inherent in this endeavor is the need to transfer the communication technology developed for lunar missions to deep space whenever possible. Furthermore, greater data throughput on the uplink will be required for future nominal operations for the Exploration missions given their highly interactive nature and the need to send files in both directions. Therefore, it is prudent for standards bodies i.e., CCSDS to develop the underlying communication recommendations necessary to deliver greater data throughput to meet future agencies' needs.

link layer↗
NASA NTRS2019

Method for Tracking and Communicating Aggregate Risk Through the Use of Model-Based Systems Engineering (MBSE) Tools

Large, complex projects can identify a significant number and variety of risks, throughout the project life cycle. These risks are analyzed, mitigated, closed or accepted as independent uncertainties. Once closed or accepted, it is easy for projects to lose awareness of their impact. In reality, each of these risks contributes some amount to the overall risk posture of the project. The ability to track and effectively communicate this aggregate risk has represented a challenge to project management. There have been previous attempts to create a schema to communicate the aggregate effect of risks, without notable success. Most of these attempts have centered on some additive metric derived from the scoring of likelihood and consequence values. This, in and of itself, is a logical approach, but all too often the scores were then aggregated to a level where all context was lost. One weakness has been a lack of attempt to create linkages or logical groups of the risks upon which useful aggregation could then occur. The overall move to model-based (systems) engineering (MBSE) has opened up a vast frontier of opportunities to better integrate all project data. MBSE provides an underlying layer that links data items to each other. Objectives link to requirements, which then link to functions, functions to physical architecture items, and so on, as far down as projects want to model. While it started with a focus on modeling requirements based on things like use cases, efforts are now underway to integrate safety and mission assurance (S&MA) information and analyses, such as risks. This effort, called Model Based Mission Assurance (MBMA), is yielding models that are more useful and are a more accurate representations of the systems. MBSE models, with this ability to link related items, provide a new means of tracking and communicating aggregate risks. In the proposed method, risks are added into the models as distinct items, having attributes that communicate a scoring derived from the likelihood and consequence values as charted on the standard NASA 5x5 risk matrix. Like earlier efforts, each box in the 5x5 has an associated scoring, which may include both a current score and potential post-mitigation/control score. The risk items are then linked to elements of the model, such as system objectives/goals, requirements, functions, or physical architecture items, with "Risk to" relationships. These risks will then be communicated by use of reports generated from the model, detailing all risks and/or hazards linked to model elements. These reports can include aggregate impacts, including a current scoring and potential future state scoring based on the planned mitigations and/or controls. These reports will show all risks, open, accepted, and closed, linked to project objectives or requirements. When run as part of an upcoming risk acceptance discussion, these reports will serve to remind the team of all previous risks that relate to the effected portion of the system. When included as part of periodic program or project reviews, risk reviews, and safety reviews, this method can improve the overall understanding of the system's true risk posture. This proposed method takes full advantage of the advances that modern modeling techniques provide, with a minimal investment of additional time. Utilizing the model environment also enables a near constant access to current state of aggregate risks.

model based mission assurance↗
DOE OSTI2025

Layer-by-layer growth of graphene oxide multilayers using robust interlayer linking chemistry. 1. Zr-bisphosphates

Graphene oxide (GO) holds substantial interest because of its utility in applications ranging from chemical sensing to catalysis and energy storage. We report on the layer-by-layer formation of graphene oxide phosphate (P-GO) multilayers on silica and oxidized silicon supports, with the layers connected via Zr-bisphosphate (ZP) linking chemistry. Layers were grown either directly by ZP linkages between P-GO sheets, or with the use of 1,4-phenylene bisphosphate (BP1) or [1,1′-biphenyl]4,4′-diyl bisphosphate (BP2). The layers have been characterized using optical null ellipsometry, X-ray photoelectron spectroscopy (XPS), UV-visible absorption spectroscopy and scanning electron microscopy (SEM). There is a linear dependence of assembly thickness on the number of layers deposited and the integrated area of the optical absorbance bands also increases linearly with number of layers deposited. XPS data provides information on interlayer linking stoichiometry. SEM images provide insight into the morphology of the adlayers, suggesting the structure and length of the interlayer linking moieties used in the multilayer assembly play a significant role in the organization of the resulting system.

Mukherjee, Neelanjana [Michigan State University, ↗
DOE OSTI2021

Understanding why poly(acrylic acid) works: decarbonylation and cross-linking provide an ionically conductive passivation layer in silicon anodes

Poly(acrylic acid) (PAA) is commonly used as a binder for fabricating silicon (Si) anode active materials in lithium-ion batteries due to its useful properties including high polar solvent solubility, good rheology, and strong adhesive properties. However, the role and evolution of PAA during electrode fabrication, cycling, and calendar aging are not well understood. In this work, we reveal the evolution of PAA during electrode curing and relate its chemical change to the final electrode properties and performance. These studies are made possible using two types of in situ attenuated total reflectance-infrared Fourier transform (ATR-FTIR) spectroscopy: thermal ATR-FTIR to probe the cross-linking reaction, and ATR-FTIR spectroelectrochemistry of three-dimensional composite electrodes, a unique technique developed herein that probes the solvation dynamics of lithium ions at the silicon anode interface under electrochemical polarization. Specifically, we show that PAA undergoes a thermally-mediated, cross-linking decarbonylation reaction to form an ether-based network polymer. To show the importance of the polyether moieties, we synthesize partially esterified PAA analogues that do not undergo this cross-linking decarbonylation reaction and correlate the degree of cross-linking to half-cell performance metrics. Finally, we unveil the mechanism of the polyether binder performance through in situ ATR-FTIR spectroelectrochemistry and show that PAA acts as an interfacial material that conducts lithium-ions, limits solvent molecule access to the Si surface, and stabilizes the electrode against parasitic lithium inventory loss at high state of charge for an extended period of time.

25 ENERGY STORAGE↗
DOE OSTI2022

Layered structures of assembled imine-linked macrocycles and two-dimensional covalent organic frameworks give rise to prolonged exciton lifetimes

Ordered organic materials and assemblies have great potential to be tailored to have desirable properties for optoelectronic applications, such as long exciton lifetime and high directional exciton mobility. Framework materials, such as two-dimensional covalent organic frameworks (2D COFs), as well as their truncated macrocyclic analogues, are versatile platforms to organize functional aromatic systems into designed assemblies and robust materials. In this study we investigate the exciton dynamics in a 2D COF, its corresponding hexagonal macrocycle, and extended nanotubes comprised of stacked macrocycles. The excitonic behavior of these three systems provide an understanding of excitonic processes that occur in the plane of the covalently bonded 2D macromolecules and between layers of the nanotubes and 2D COF. The nanotube and analogous 2D COF exhibit longer excited-state lifetimes (~100 ps) compared to the individual, solvated macrocycles (<0.5 ps). These differences are attributed to the internal conversion facilitated by the internal motions of the imine linkages which are significantly reduced in the assembled macrocycles in the nanotube and 2D COF sheets in the layered structures. The exciton diffusion processes in the assembled nanotubes and 2D COF systems were characterized by the autocorrelations of the transition dipole moment of the excitons, giving the depolarization time constants for both systems to be ~1 ps. This work also reveals the anisotropic exciton dynamics related to the in-plane and inter-plane structural factors in these systems. These studies provide guidance for the design of future COF materials, where the longer excited state lifetimes imparted by assembly are beneficial for optoelectronic applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1991

All high Tc edge-geometry weak links utilizing Y-Ba-Cu-O barrier layers

High quality YBa2Cu3O(7-x) normal-metal/YBa2Cu3O(7-x) edge-geometry weak links have been fabricated using nonsuperconducting Y-Ba-Cu-O barrier layers deposited by laser ablation at reduced growth temperatures. Devices incorporating 25-100 A thick barrier layers exhibit current-voltage characteristics consistent with the resistively shunted junction model, with strong microwave and magnetic field response at temperatures up to 85 K. The critical currents vary exponentially with barrier thickness, and the resistances scale linearly with Y-Ba-Cu-O interlayer thickness and device area, indicating good barrier uniformity, with an effective mormal metal coherence length of 20 A.

Hunt, B. D.↗
DOE OSTI2024

A Four-Layer Cyber-Physical Security Model for Electric Machine Drives Considering Control Information Flow

Despite the IEEE Power Electronics Society (PELS) establishing Technical Committee 10 on Design Methodologies with a focus on the cyber-physical security of power electronics systems, a holistic design methodology for addressing security vulnerabilities remains underdeveloped. This gap largely stems from the limited integration of computer science and power/control engineering studies in this interdisciplinary field. Addressing the inadequacy of unilateral cyber or control perspectives, this article presents a novel four-layer cyber-physical security model specifically designed for electric machine drives. Central to this model is the innovative control information flow (CIF) model, residing within the control layer, which serves as a pivotal link between the cyber layer's vulnerable resources and the physical layer's state-space models. By mapping vulnerable resources to control variable space and tracing attack propagation, the CIF model facilitates accurate impact predictions based on tainted control laws. The effectiveness and validity of this proposed model are demonstrated through hardware experiments involving two typical cyber-attack scenarios, underscoring its potential as a comprehensive framework for multidisciplinary security strategies.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Layer-by-layer growth of graphene oxide multilayers using robust interlayer linking chemistry. 2 Zr–bissulfates

We report on the facile layer-by-layer growth of graphene oxide sulfate (GO-S) multilayer structures. The layers are bonded to a modified planar silica support using Zr 4+ ions. Optical ellipsometry shows step-by-step layer growth with layer thickness consistent with that expected from molecular mechanics calculations. The reaction to form Zr–bissulfate linkages is facile, with multistep layer deposition occurring within six to ten minutes per layer. The GO-S layers can be deposited directly on GO-S underlayer(s) or interlayer spacers can be incorporated to control the spacing with GO-S layers. X-ray photoelectron spectroscopy (XPS) data provides information on the density of the sulfonated groups present at the graphene oxide surface and on the Zr : S ratio. This is the first report we are aware of that demonstrates robust layer-by-layer growth of graphene oxide structures.

Graphene oxide↗
NASA NTRS2004

Mars: The Terra Arabia Low Epithermal Neutron Flux Anomaly

The High Energy Neutron Spectrometer (HEND) and Neutron Specrometer, part of the Mars Odyssey Gamma Ray Spectrometer suite of instruments, measured anomalously low epithermal neutron flux in two low-latitude areas, Terra Arabia and SW of Olympus Mons (SWOM). The low epithermal neutron flux, an indirect measure of Hydrogen abundance, is indicative of relatively high water content (in this case up to 8 mass percent) in the upper 1-2 m of the surface layer. The epithermal flux within the 60 degree latitude zone does not correlate with bedrock geology or topography but partially correlates (for Arabia) with thermal inertia. According to theoretical estimates for the current geologic epoch, ground ice should not be stable at this depth at these low latitudes so it was concluded that the anomalies are due to the presence of chemically bound water (e.g. clays, hydroxides or hydrosalts). Fast neutron flux, which is indicative of the presence of water at 20-30 cm depth, does not correlate in this latitude zone with the epithermal neutron flux. As a further step of the analysis a geotraverse including study of 152 high resolution MOC images within the Arabia anomaly was done by to find out if the area inside the anomaly differs from the neighboring areas by the presence of fluvial channels and layered deposits (possible links to chemically bound water) or in thickness and apparent texture of the surface layer. No differences were found.

Basilevsky, A. T.↗
NASA NTRS2001

Considerations and Architectures for Inter-Satellite Communications in Distributed Spacecraft Systems

This paper will identify the important characteristics and requirements necessary for inter-satellite communications in distributed spacecraft systems and present analysis results focusing on architectural and protocol comparisons. Emerging spacecraft systems plan to deploy multiple satellites in various "distributed" configurations ranging from close proximity formation flying to widely separated constellations. Distributed spacecraft configurations provide advantages for science exploration and operations since many activities useful for missions may be better served by distributing them between spacecraft. For example, many scientific observations can be enhanced through spatially separated platforms, such as for deep space interferometry. operating multiple distributed spacecraft as a mission requires coordination that may be best provided through inter-satellite communications. For example, several future distributed spacecraft systems envision autonomous operations requiring relative navigational calculations and coordinated attitude and position corrections. To conduct these operations, data must be exchanged between spacecraft. Direct cross-links between satellites provides an efficient and practical method for transferring data and commands. Unlike existing "bent-pipe" relay networks supporting space missions, no standard or widely-used method exists for cross-link communications. Consequently, to support these future missions, the characteristics necessary for inter-satellite communications need to be examined. At first glance, all of the missions look extremely different. Some missions call for tens to hundreds of nano-satellites in constant communications in close proximity to each other. Other missions call for a handful of satellites communicating very slowly over thousands to hundreds of thousands of kilometers. The paper will first classify distributed spacecraft missions to help guide the evaluation and definition of cross-link architectures and approaches. Based on this general classification, the paper will examine general physical layer parameters, such as frequency bands and data rates, necessary to support the missions. The paper will also identify classes of communication architectures that may be employed, ranging from fully distributed to centralized topologies. Numerous factors, such as number of spacecraft, must be evaluated when attempting to pick a communications architecture. Also important is the stability of the formation from a communications standpoint. For example, do all of the spacecraft require equal bandwidth and are spacecraft allowed to enter and leave a formation? The type of science mission being attempted may also heavily influence the communications architecture. In addition, the paper will assess various parameters and characteristics typically associated with the data link layer. The paper will analyze the performance of various multiple access techniques given the operational scenario, requirements, and communication topologies envisioned for missions. This assessment will also include a survey of existing standards and their applicability for distributed spacecraft systems. An important consideration includes the interoperability of the lower layers (physical and data link) examined in this paper with the higher layer protocols(network) envisioned for future space internetworking. Finally, the paper will define a suggested path, including preliminary recommendations, for defining and developing a standard for intersatellite communications based on the classes of distributed spacecraft missions and analysis results.

Edwards, Bernard↗