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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 397 records · Page 22
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Production and Early Preservation of Lipid Biomarkers in Iron Hot Springs

The bicarbonate-buffered anoxic vent waters at Chocolate Pots hot springs in Yellowstone National Park are 51–54°C, pH 5.5–6.0, and are very high in dissolved Fe(II) at 5.8–5.9 mg/L. The aqueous Fe(II) is oxidized by a combination of biotic and abiotic mechanisms and precipitated as primary siliceous nanophase iron oxyhydroxides (ferrihydrite). Four distinct prokaryotic photosynthetic microbial mat types grow on top of these iron deposits. Lipids were used to characterize the community composition of the microbial mats, link source organisms to geologically significant biomarkers, and investigate how iron mineralization degrades the lipid signature of the community. The phospholipid and glycolipid fatty acid profiles of the highest-temperature mats indicate that they are dominated by cyanobacteria and green nonsulfur filamentous anoxygenic phototrophs (FAPs). Diagnostic lipid biomarkers of the cyanobacteria include midchain branched mono- and dimethylalkanes and, most notably, 2-methylbacteriohopanepolyol. Diagnostic lipid biomarkers of the FAPs (Chloroflexus and Roseiflexus spp.) include wax esters and a long-chain tri-unsaturated alkene. Surprisingly, the lipid biomarkers resisted the earliest stages of microbial degradation and diagenesis to survive in the iron oxides beneath the mats. Understanding the potential of particular sedimentary environments to capture and preserve fossil biosignatures is of vital importance in the selection of the best landing sites for future astrobiological missions to Mars. Finally, this study explores the nature of organic degradation processes in moderately thermal Fe(II)-rich groundwater springs—environmental conditions that have been previously identified as highly relevant for Mars exploration.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2019

Beam emittance preservation using Gaussian density ramps in a beam-driven plasma wakefield accelerator

A current challenge that is facing the plasma wakefield accelerator (PWFA) community is transverse beam emittance preservation. This can be achieved by balancing the natural divergence of the beam against the strong focusing force provided by the PWFA plasma source in a scheme referred to as beam matching. One method to accomplish beam matching is through the gradual focusing of a beam with a plasma density ramp leading into the bulk plasma. Here, the beam dynamics in a Gaussian plasma density ramp are considered, and an empirical formula is identified that gives the ramp length and beam vacuum waist location needed to achieve near-perfect matching. The method uses only the beam vacuum waist beta function as an input. Numerical studies show that the Gaussian ramp focusing formula is robust for beta function demagnification factors spanning more than an order of magnitude with experimentally favourable tolerances for future PWFA research facilities. This article is part of the Theo Murphy meeting issue ‘Directions in particle beam-driven plasma wakefield acceleration’.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

Large-surface-area diamond (111) crystal plates for applications in high-heat-load wavefront-preserving X-ray crystal optics

Fabrication and results of high-resolution X-ray topography characterization of diamond single-crystal plates with large surface area (10 mm × 10 mm) and (111) crystal surface orientation for applications in high-heat-load X-ray crystal optics are reported. The plates were fabricated by laser-cutting of the (111) facets of diamond crystals grown using high-pressure high-temperature methods. The intrinsic crystal quality of a selected 3 mm × 7 mm crystal region of one of the studied samples was found to be suitable for applications in wavefront-preserving high-heat-load crystal optics. Wavefront characterization was performed using sequential X-ray diffraction topography in the pseudo plane wave configuration and data analysis using rocking-curve topography. In conclusion, the variations of the rocking-curve width and peak position measured with a spatial resolution of 13 µm × 13 µm over the selected region were found to be less than 1 µrad.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Structure of Respiratory Syncytial Virus Fusion Glycoprotein in the Postfusion Conformation Reveals Preservation of Neutralizing Epitopes

Respiratory syncytial virus (RSV) invades host cells via a type I fusion (F) glycoprotein that undergoes dramatic structural rearrangements during the fusion process. Neutralizing monoclonal antibodies, such as 101F, palivizumab, and motavizumab, target two major antigenic sites on the RSV F glycoprotein. The structures of these sites as peptide complexes with motavizumab and 101F have been previously determined, but a structure for the trimeric RSV F glycoprotein ectodomain has remained elusive. To address this issue, we undertook structural and biophysical studies on stable ectodomain constructs. Here, we present the 2.8-{angstrom} crystal structure of the trimeric RSV F ectodomain in its postfusion conformation. The structure revealed that the 101F and motavizumab epitopes are present in the postfusion state and that their conformations are similar to those observed in the antibody-bound peptide structures. Both antibodies bound the postfusion F glycoprotein with high affinity in surface plasmon resonance experiments. Modeling of the antibodies bound to the F glycoprotein predicts that the 101F epitope is larger than the linear peptide and restricted to a single protomer in the trimer, whereas motavizumab likely contacts residues on two protomers, indicating a quaternary epitope. Mechanistically, these results suggest that 101F and motavizumab can bind to multiple conformations of the fusion glycoprotein and can neutralize late in the entry process. The structural preservation of neutralizing epitopes in the postfusion state suggests that this conformation can elicit neutralizing antibodies and serve as a useful vaccine antigen.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

A Framework for Privacy-Preserving Data Publishing with Enhanced Utility for Cyber-Physical Systems

Cyber-physical systems have enabled the collection of massive amounts of data in an unprecedented level of spatial and temporal granularity. Publishing these data can prosper big data research, which, in turn, helps improve overall system efficiency and resiliency. The main challenge in data publishing is to ensure the usefulness of published data while providing necessary privacy protection. In our previous work (Jia et al. 2017a), we presented a privacy-preserving data publishing framework (referred to as PAD hereinafter), which can guarantee k-anonymity while achieving better data utility than traditional anonymization techniques. PAD learns the information of interest to data users or features from their interactions with the data publishing system and then customizes data publishing processes to the intended use of data. However, our previous work is only applicable to the case where the desired features are linear in the original data record. In this article, we extend PAD to nonlinear features. Our experiments demonstrate that for various data-driven applications, PAD can achieve enhanced utility while remaining highly resilient to privacy threats.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2020

Preserving Manhattan Project historic sites

Beginning in 1943, Project Y – the code name for Los Alamos during World War II – transformed the isolated Pajarito Plateau. The sounds of construction equipment replaced the voices of the Los Alamos Ranch School boys and local homesteaders. Construction crews hurriedly built many structures on mesa tops and in the canyons of Los Alamos. Countless concerns flooded Manhattan Project staff, but designing structures to withstand the test of time was not one of them. The top-secret race to develop an atomic bomb before Nazi Germany was on and everyone felt the pressure. Over the next 75 years, some of the structures slumped into disrepair from exposure to the harsh northern New Mexico environment - concrete cracking and spalling, wood frames rotting. That’s where Los Alamos National Laboratory’s historic preservation team enters the Manhattan Project story.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗
NASA NTRSDate not supplied

Benefits of a Proposed Process to Preserve Lunar Sites

Assets in lunar orbit and on the surface, whether operational or defunct, have the ability to cause inadvertent interference with proximity operations. As missions to the Moon continue to proliferate, and as more actors become involved, a mechanism is needed to bring communities together to ensure ones' actions do not inhibit the mission objectives of another. A mechanism may also be needed to determine whether any locations on the Moon or in its orbit are of high value to various users, and, pending potential decreases in this value due to interference and other concerns, warrant mitigative actions to preserve these locations. Such a mechanism could provide benefits to all those involved, including governments, industry, academia, and other interested groups. We present a notional process to aggregate community interests for lunar sites and orbits. We then consider two user needs and explore how this process could be used to identify potential alignments and misalignments across communities.

preservation↗
DOE OSTI2011

Knowledge Preservation at the Fast Flux Test Facility

The Fast Flux Test Facility (FFTF) is the most recent Liquid Metal Reactor (LMR) to operate in the United States, from 1982 to 1992. The technologies employed in designing and constructing this reactor, along with information obtained from tests conducted during its operation, are currently being secured and archived by the Department of Energy's Office of Nuclear Energy. This report provides a status update documenting the overall project efforts to retrieve and preserve critical information related to advanced reactors.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2012

Near integer tune for polarization preservation in the AGS

The high energy (T = 250 GeV) polarized proton beam experiments performed in RHIC, require high polarization of the beam. In order to preserve the polarization of the proton beam, during the acceleration in the AGS, which is the pre-injector to RHIC, we have installed in AGS two partial helical magnets which minimize the loss of the beam polarization caused by the various intrinsic spin resonances occurring during the proton acceleration. The minimization of the polarization loss during the acceleration cycle, requires that the vertical tune of the AGS is between the values of 8.97 and 8.985 during the acceleration. With the AGS constrained to run at near integer tune {approx}8.980, the perturbations to the beam caused by the partial helical magnets are large and also result in large beta and dispersion waves. To mitigate the adverse effect of the partial helices on the optics of the AGS, we have installed in specified straight sections of the AGS compensation quads and we have also generated a beam bump at the location of the cold partial helix. In this paper we present the beam optics of the AGS which ameliorates the adverse effect of the two partial helices on the beam optics.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

The National Historic Preservation Act is Not Your Problem, But How You are Addressing it for Your CERCLA Project May Be - 12344

The 1995 Environmental Protection Agency (EPA) and U.S. Department of Energy (DOE) joint 'Policy on Decommissioning of Department of Energy Facilities Under CERCLA was developed so that decommissioning could occur in a manner that ensures protection of worker and public health and the environment, that is consistent with Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), that provides for stakeholder involvement, and that achieves risk reduction without unnecessary delay'. The source of the 'unnecessary delays' the joint policy intended to avert could be attributed to numerous factors such as obtaining permits, conducting administrative activities, or implementing regulatory processes that could yield, among other things, differing preferred alternatives. Why, you might ask, more than fifteen years later, does DOE continue to struggle through CERCLA projects with unnecessary delays? From problem identification, to determination of nature and extent, to alternative analysis and ultimately remedy selection and implementation, reaching a compliant and effective clean-up end-point can be a process that seems to mimic geologic timescales. The source of these delays is often the failure to use all of the tools the CERCLA process offers. As one example, renewed commitment to follow the CERCLA process to address the regulatory reviews pursuant to the National Historic Preservation Act (NHPA) is called for. Project managers implementing CERCLA actions in any agency, not only DOE, do not need to be apprehensive about using the CERCLA process for NHPA review but should welcome it. It is critical that methods are used that address substantive NHPA requirements clearly and consistently, and that they are shared and communicated as frequently as needed to interested and questioning stakeholders. (author)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2018

Preserved Neoproterozoic Continental Collision in Southeastern North America: The Brunswick Suture Zone and Osceola Continental Margin Arc

A series of exotic terranes were accreted to the eastern margin of southeastern Laurentia beginning in the Siluro-Devonian (Acadian event), and to the northeastern Laurentian margin beginning earlier (late Taconian). Many of these terranes have unclear tectonostratigraphic relationships to each other and to their parental cratons, but their accretionary history is critical to understanding the evolution of the Appalachian orogen. Two of these, the Gondwanan Suwannee and Charleston terranes, accreted during the Alleghanian orogeny and now lie beneath the Atlantic Coastal Plain in southeastern North America. Reanalysis of deep seismic reflection and well data reveals a preserved Neoproterozoic continental collision zone and associated continental margin arc, the Osceola arc, related to their juxtaposition. The subduction zone and associated strain are recorded in the newly termed Brunswick suture zone (BSZ). The BSZ is readily identified on a series of eight deep seismic reflection transects across the Brunswick Magnetic Anomaly (BMA), which we interpret as the boundary between the Charleston and Suwannee terranes. While originally interpreted to be the Late Paleozoic Alleghanian suture, new age constraints provided by the overlapping Gondwanan Paleozoic Suwannee Basin strata require the BSZ to predate the Early to Middle Paleozoic passive margin sequence of the Suwannee Basin. These results provide new insights into the tectonostratigraphic evolution of the Charleston and Suwannee terranes, the controversy surrounding the age and origin of the dipping seismic reflectors, previously attributed to the suturing of the Suwannee terrane to Laurentia, and the relationship of this suture zone to the origin of the BMA.

58 GEOSCIENCES↗
DOE OSTI2019

Shape-Preserved Transformation of Biological Cells into Synthetic Hydrogel Microparticles

The synthesis of materials that can mimic the mechanical, and ultimately functional, properties of biological cells can broadly impact the development of biomimetic materials, as well as engineered tissues and therapeutics. Yet, it is challenging to synthesize, for example, microparticles that share both the anisotropic shapes and the elastic properties of living cells. Here in paper, a cell-directed route to replicate cellular structures into synthetic hydrogels such as polyethylene glycol (PEG) is described. First, the internal and external surfaces of chemically fixed cells are replicated in a conformal layer of silica using a sol–gel process. The template is subsequently removed to render shape-preserved, mesoporous silica replicas. Infiltration and cross-linking of PEG precursors and dissolution of the silica result in a soft hydrogel replica of the cellular template as demonstrated using erythrocytes, HeLa, and neuronal cultured cells. The elastic modulus can be tuned over an order of magnitude (≈10–100 kPa) though with a high degree of variability. Furthermore, synthesis without removing the biotemplate results in stimuli-responsive particles that swell/deswell in response to environmental cues. Overall, this work provides a foundation to develop soft particles with nearly limitless architectural complexity derived from dynamic biological templates.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Preserving Structurally Labile Peptide Nanosheets After Molecular Functionalization of the Self-Assembling Peptides

A significant challenge in creating supramolecular materials is that conjugating molecular functionalities to building blocks often results in dissociation or undesired morphological transformation of their assemblies. Here we present a facile strategy to preserve structurally labile peptide assemblies after molecular modification of the self-assembling peptides. Sheet-forming peptides are designed to afford a staggered alignment with the segments bearing chemical modification sites protruding from the sheet surfaces. The staggered assembly allows for simultaneous separation of attached molecules from each other and from the underlying assembly motifs. Strikingly, using PEGs as the external molecules, PEG 400 - and PEG 700 -peptide conjugates directly self-associate into nanosheets with the PEG chains localized on the sheet surfaces. In contrast, the sheet formation based on in-register lateral packing of peptides does not recur upon the peptide PEGylation. This strategy allows for fabrication of densely modified assemblies with a variety of molecules, as demonstrated using biotin (hydrophobic molecule), c(RGDfK) (cyclic pentapeptide), and nucleic acid aptamer (negatively charged ssDNA). The staggered co-assembly also enables extended tunability of the amount/density of surface molecules, as exemplified by screening ligand-appended assemblies for cell targeting. In conclusion, this study paves the way for functionalization of historically challenging fragile assemblies while maintaining their overall morphology.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Preserving the Josephson Coupling of Twisted Cuprate Junctions via Tailored Silicon Nitride Circuits Boards

Controlled fabrication of twisted van der Waals heterostructures is essential to unlock the full potential of moiré materials. However, achieving reproducibility remains a major challenge, particularly for air-sensitive materials such as Bi 2 Sr 2 CaCu 2 O 8 + δ (BSCCO), where it is crucial to preserve the intrinsic and delicate superconducting properties of the interface throughout the entire fabrication process. Here, a dry, inert and cryogenic assembly method is presented that combines silicon nitride nanomembranes (NMBs) with pre-patterned electrodes and the cryogenic stacking technique (CST) to fabricate high-quality twisted BSCCO Josephson junctions (JJs). This protocol prevents thermal and chemical degradation during both interface formation and electrical contact integration. It is also found that asymmetric membrane designs, such as a double cantilever, effectively suppress vibration-induced disorder due to wire bonding, resulting in sharp and hysteretic current–voltage characteristics. The junctions exhibit a twist-angle-dependent Josephson coupling with magnitudes comparable to the highest-performing devices reported to date, but achieved through a straightforward and versatile contact method, offering a scalable and adaptable platform for future applications. These findings highlight the importance of both interface and contact engineering in addressing reproducibility in superconducting van der Waals heterostructures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2026

IntraShuffler: A Privacy Preserving Framework for Heterogeneous DP Federated Learning

Heterogeneous Differential Privacy (HDP) in Federated Learning (FL) allows clients to select individual privacy budgets () according to institutional policies and data sensitivity. In practice, many HDP-FL systems employ -aware server aggregation to improve model utility by re-weighting client updates according to their declared privacy budgets. However, gradient updates in FL retain structural patterns induced by non-independent and identically-distributed (non-IID) data, and these additional signals exposed by -aware aggregation create new opportunities for inference by an honest-but-curious server. In this work, we first show that a server equipped with gradient denoising and surrogate modeling can mount a Privacy Inference Attack that infers distributional attributes of clients and links updates from the same client across training rounds, measured via surrogate inference accuracy and linkage success, under realistic knowledge constraints. The Shuffle-Model has been widely studied as a defense against such inference risks by anonymizing update sources, but it is fundamentally incompatible with HDP-FL -aware aggregation. To address this challenge, we propose IntraShuffler, a middleware defense framework designed for HDP-FL systems. IntraShuffler introduces a privacy-aware shuffling mechanism that groups clients into privacy-compatible buckets and performs parameter-level shuffling within each bucket to disrupt persistent gradient structure while preserving -aware aggregation. Experiments across four different datasets show that IntraShuffler reduces gradient recoverability by over 60% and decreases surrogate inference accuracy from 0.78 to 0.33 while maintaining comparable model utility across multiple FL aggregation rules.

Riya, Farhin Farhad [ORNL]↗
DOE OSTI2026

Can black holes preserve 𝒩 > 4 supersymmetry?

The dynamics of near-BPS black holes are governed by the breaking of the conformal symmetry that emerges near their horizons. Using the classification of superconformal symmetries, we systematically classify and quantize all effective theories that can arise in the near-BPS limit of black holes. Using these results, we argue — under certain physical assumptions — that BPS black holes cannot preserve more than four supercharges. This conclusion is consistent with existing constructions in string theory.

Black Holes in String Theory↗