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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 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Time-Resolved Optical Pump-Resonant X-ray Probe Spectroscopy of 4-Thiouracil: A Simulation Study

We theoretically monitor the photoinduced ππ* → nπ* internal conversion process in 4-thiouracil (4TU), triggered by an optical pump. The element-sensitive spectroscopic signatures are recorded by a resonant X-ray probe tuned to the sulfur, oxygen, or nitrogen K-edge. We employ high-level electronic structure methods optimized for core-excited electronic structure calculation combined with quantum nuclear wavepacket dynamics computed on two relevant nuclear modes, fully accounting for their quantum nature of nuclear motions. We critically discuss the capabilities and limitations of the resonant technique. For sulfur and nitrogen, we document a pre-edge spectral window free from ground-state background and rich with ππ* and nπ* absorption features. The lowest sulfur K-edge shows strong absorption for both ππ* and nπ*. In the lowest nitrogen K-edge window, we resolve a state-specific fingerprint of the ππ* and an approximate timing of the conical intersection via its depletion. A spectral signature of the nπ* transition, not accessible by UV–vis spectroscopy, is identified. The oxygen K-edge is not sensitive to molecular deformations and gives steady transient absorption features without spectral dynamics. Here, the ππ*/nπ* coherence information is masked by more intense contributions from populations. Altogether, element-specific time-resolved resonant X-ray spectroscopy provides a detailed picture of the electronic excited-state dynamics and therefore a sensitive window into the photophysics of thiobases.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

Application of Banking Scoring and Rating for Coherent Risk Measures in Electricity Systems ABSCORES

This project developed a framework for asset and system risk management that can be incorporated into current electricity system operations to improve economic efficiency and establish an Electric Assets Risk Bureau. We leveraged scoring and ratings from banking and financial institutions alongside current optimization methods in dispatching power systems to help system operators and electricity markets schedule resources. This approach is based on the observation that there are major discrepancies between the power scheduled by a system operator and the actual power generated/consumed. These discrepancies—exacerbated by unplanned contingencies (e.g., natural disasters)—are caused by multiple factors, including the different financial, environmental and risk preferences of power producers, consumers, and aggregators. We developed a framework that counteracts two failures in electricity system operations: imperfect information and missing markets for products. The technical approach included five tasks. Tasks 1 and 2 supported the development of risk scores at the asset level with historical data collected for this project. Tasks 3, 4, and 5 incorporated scoring into decision-making at the system level. The proposed effort achieved PERFORM's Program Objectives because the proposed outputs and algorithms do not exist in the electricity industry and are an innovative approach to managing risk. Since the acknowledged need to better assess and act upon risk profiles for grid assets has not been met by the industry, this project will also impact ARPA-E's Mission Areas, including improving energy efficiency and giving the U.S. a technological lead in advanced energy technologies.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2019

Ground-state and stability properties of 288-308 118 Og isotopes based on semi-microscopic calculations

In this study, we present theoretical predictions on the stability properties of the yet unknown {sup 276−293,295−308}{sub 118}Og isotopes using the Skyrme-SLy4 nucleon–nucleon interaction and the deformed Woods–Saxon single-particle potential in a semi-microscopic approach. The ground-state masses, binding energy, deformations and fission barriers are calculated from the total energy surfaces produced in a multidimensional deformation space using the dynamical differential evolution optimization method. Besides, the Q-values of the different decay modes and the nucleon separation energies for each isotope, and its α-decay (T{sub α}) and spontaneous fission half-lives are also calculated. Our study revealed the {sub 290−296}Og elements to be the most bound Oganesson isotopes, among which {sup 302,304,306}Og elements are predicted to be spherical nuclei, and {sup 299,300,301,303,305}Og elements are shown to be almost spherical. The predicted ground-state and decay properties successfully reproduced the available data of the solely known Oganesson isotope {sup 294}Og. In addition to the principle α-decay modes, we studied the rival decay modes that challenge the stability of nuclei in the superheavy regions, namely the electron capture β{sup +} decays and the spontaneous fission. An overall oscillating increasing behavior of T{sub α} with the mass number is obtained, which obviously reverses the hesitating decreasing behavior of Q{sub α} and follows increasing trend of the corresponding change in the neutron-skin thickness after α-decays. The {sub 291,294−296,299−302}Og isotopes are expected to have relatively long half-lives, T{sub α} ≈ 1–45 ms, while {sup 295}Og is found to have the longest half-life between the considered nuclei. The {sub 291−300}Og isotopes exhibited relatively high fission barriers and small branching ratios for their spontaneous fission modes.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

SU-E-T-95: Delivery Time Estimator

Purpose: The development and testing of a tool for the inclusion of delivery time as a parameter in plan optimization. Methods: We developed an algorithm that estimates the time required for the machine and personnel movements required to deliver a treatment plan on a linear accelerator. We included dose rate, leaf motion, collimator motion, gantry motion, and couch motions (including time to enter the room to rotate the couch safely). Vault-specific parameters to account for time to enter and perform couch angle adjustments were also included. This algorithm works for static, step and shoot IMRT, and VMAT beams photon beams and for fixed electron beams. This was implemented as a script in our treatment planning system. We validated the estimator against actual recorded delivery time from our R and V system as well as recorded times from our IMRT QA delivery. Results: Data was collected (Figure 1) for 12 treatment plans by examining the R and V beam start times, and by manually timing the QA treatment for a reference, but the QA measurements were only significant to the nearest minute. The average difference between the estimated and R and V times was 15%, and 11% when excluding the major outliers. Outliers arose due to respiratory aides and gating techniques which could not be accounted for in the estimator. Conclusion: Non-mechanical factors such as the time a therapist needs to walk in and out of the room to adjust the couch needed to be fine-tuned and cycled back into the algorithm to improve the estimate. The algorithm has been demonstrated to provide reasonable and useful estimates for delivery time. This estimate has provided a useful additional input for clinical decision-making when comparing several potential radiation treatment options.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2022

Broadband Asymmetric Transmission of Linearly Polarized Mid‐Infrared Light Based on Quasi‐3D Metamaterials

Abstract Metamaterials consisting of subwavelength resonators offer an exciting opportunity for realizing asymmetric transmission (AT) of linearly polarized light. However, to date, only moderate/narrow‐band AT responses have been obtained in metadevices based on stacked planar nanostructures. Here, leveraging a combination of a genetic algorithm (GA) based optimization method and a membrane projection lithography (MPL) fabrication approach, a quasi‐3D metamaterial for broadband AT of linearly polarized mid‐infrared light is demonstrated. Facilitated by the customized GA, an efficient exploration of 3D plasmonic meta‐atoms with broken mirror symmetry in the light propagation direction allows the satisfaction of the rigorous conditions for AT of linearly polarized waves over a broad wavelength range. Confirmed by surface current analysis, the observed AT behavior is attributed to the resonant coupling between the plasmonic nanostructures located on the two orthogonal walls of the MPL cavities. Incorporating an advanced inverse‐design method and a state‐of‐art fabrication technique, the methodology used in the present study provides a promising route for exploiting 3D metamaterials with sophisticated functionalities via effectively exploring the high‐dimensional parametric space offered by true 3D meta‐atoms.

Whiting, Eric B.↗
DOE OSTI2023

Lattice Oxygen Redox Reversibility Modulation in Enhancing the Cycling Stability of Li-Rich Cathode Materials

The practical application of lithium-rich layered oxides is prohibited by the drawbacks such as severe capacity and voltage degradation resulting from unstable oxygen redox environment and the accompanied irreversible oxygen release. In this report a facile and effective strategy is proposed to regulate the oxygen redox chemistry via foreign Fe doping and its induced intrinsic transition metal (TM) doping as well as the in situ constructed spinel surface layer. The Fe doping, together with the induced intrinsic TM dual doping, can stabilize the lattice oxygen in the bulk due to the formed stronger Fe—O bond, and restrain the irreversible TM migration and then the undesirable phase transformation. More importantly, thermodynamical energy barrier of oxygen activation is dramatically decreased by the O 2p–Fe 3d charge-transfer, allowing stable oxygen redox activity. And the pre-constructed spinel layer can effectively stabilize the surface lattice oxygen and suppress harmful interfacial side-reactions. Such a simple optimizing method make the modified cathode exhibit a high specific capacity of 298 mAh g -1 at 0.2 C, outstanding cycling stability with a superior capacity and voltage retentions of 92.5% and 90.8%, respectively, after 400 cycles at 1 C. This study provides a new direction for developing advanced Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2023

Perovskite Solar Module: Promise and Challenges in Efficiency, Meta‐Stability, and Operational Lifetime

Abstract Perovskite photovoltaics (PVs) are an emerging solar energy generation technology that is nearing commercialization. Despite the unprecedented progress in increasing power conversion efficiency (PCE) for perovskite solar cells (PSCs), up‐scaling lab‐made cells to solar modules remains a challenge. In this work, the recent progress of making perovskite mini‐modules is reviewed. In particular, a database summarizing the module size, performance, hysteresis, and operational lifetimes reported in the literature is built. After analyzing the performance losses from scaling PSCs to mini‐modules based on the data collected from the literature, the current key to high‐performance perovskite mini‐modules is found to be the coating method optimization. If the perovskite layer quality is well reserved, a >24% mini‐module efficiency is projected by only considering the losses from lateral resistivity and laser scribing area. Next, performance characteristics are explored including hysteresis and meta‐stable power outputs that must be overcome to correctly characterize perovskite modules. Finally, current challenges associated with the long‐term stability of perovskite modules are examined and the importance of such durability for commercialization is discussed. It is hoped that the findings in this review provide a bridge for the development of perovskite modules that will lead to commercialization in the near future.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Robust optimization for intensity-modulated proton therapy with soft spot sensitivity regularization

In this work, we developed a novel computationally efficient robust optimization method for IMPT. The robustness is calculated as the spot sensitivity to both range and shift perturbations. The dose fidelity term is then regularized by the sensitivity term for the flexibility and trade-off between the dosimetry and the robustness. In the stress test, SenR is more resilient to unexpected uncertainties. These advantages in combination with its fast computation time make it a viable candidate for clinical IMPT planning.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2021

Liquid Chromatography Mass Spectrometry study of eutectic bis(2,2-dinitropropyl) acetal/formal

This study is the first attempt to document methodology development undergone using liquid chromatography tandem quadrupole time of flight mass spectrometry (LC-QTOF) to investigate degradation products of eutectic bis(2,2-dinitropropyl) acetal/formal nitroplasticizer (called NP here). Method properties investigated are: desolvation temperature (°C) and spray voltage (V) of the electrospray ionization source, and the development of an acetone system rinse to prevent any residual contamination between sample injections. Details are given on why it is essential to investigate method optimization with changes shown in MS/MS analysis in addition to MS results. Trends in MS/MS analytic results reveal important relationships between baseline and aged materials. In addition to verification of previously proposed fragments, insights offered by this newly developed methodology will also identify new degradation products and shed light on the complexity of NP degradation chemistry.

36 MATERIALS SCIENCE↗
DOE OSTI2018

RBMK Uranium-Erbium Fuel

The history of the development and adoption of erbium fuel in RBMK is described. Research performed at the end of the 1980s – beginning of 1990s led to the conclusion that the optimal method of decreasing the steam coefficient of reactivity in RBMK is to add a consumable absorber – erbium. Computational and experimental work on the safety validation of the new fuel made it possible to adopt this fuel first in RBMK-1500 and then in RBMK-1000. The use of uranium-erbium fuel in RBMK made it possible to increase reactor safety, provide the requisite conditions for modernizing control rods, reduce the acuteness of the problem of storing spent fuel, and improve the economic indices of the fuel cycle. Considering the heightened interest in the use of erbium as a consumable absorber in VVER and some other reactors, the experience gained in developing and operating uranium-erbium fuel for RBMK could be helpful.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2018

Exfoliation and Decoration of Graphene Sheets with Silver Nanoparticles and Their Antibacterial Properties

High quality graphene sheets (GRP) have been exfoliated using facile one pot method through direct ultrasonication of graphite in the presence of polyvinyl alcohol. The GRP were decorated with silver nanoparticles (AgNPs) producing graphene–silver nanoparticle composites. The effect of variation of graphite and silver salt mass ratios on the morphology and performance of produced composites was studied. The size of AgNPs decorated on GRP has been tuned with synthesis method optimization. The average size of AgNPs was found to be in the range of 8.6–15.6 nm. Cotton–polyester blend textile fabrics were treated with the new smart developed composite as antibacterial agent producing new composites. A significant inhibition of bacterial growth has been observed for graphene–silver nanoparticle composite and the antibacterial efficiency was optimized. The clear inhibition zone for textiles treated with new developed composite and AgNPs alone was recorded as 12 and 1.75 mm respectively, achieving more than six fold improvement.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

RAPID QUANTITATION OF URANIUM FROM MIXED FISSION PRODUCT SAMPLES

Chemical similarities between U(VI) and Mo(VI) create challenges for separation and quantification of uranium from a mixed fission product sample. The purpose of this work was to demonstrate the feasibility of using Eichrom’s® UTEVA resin in addition to a tellurium spontaneous deposition to improve the quantitation of 235U using gamma spectroscopy. The optimized method demonstrated a consistent chemical yield of 74 ± 3 % for uranium. This procedure was evaluated using 1.41x1012 fissions produced from an irradiated HEU sample. The uranium was isotopically yielded by HPGe, and the minimum detectable activity (MDA) determined from the gamma spectra. The MDA for 235U, 237U, and 238U was reduced by a factor of two. The chemical isolation of uranium was successfully achieved in less than four hours, with a separation factor of 1.41x105 from molybdenum.

Haney, Morgan M.↗
DOE OSTI2019

Polymer large core optical splitter 1 × 2 Y for high-temperature operation

The design, fabrication and measurement of the properties of the large core 1 × 2 Y optical planar splitters for high-temperature operation are demonstrated. The splitters were designed by the beam propagation method optimized for operation wavelengths 650 nm and for assembling with optical fibre having core diameter 600 µm and cladding 630 µm. The splitters consisted of optical glue core and cladding layers made of Cyclo Olefin Polymer. The applied materials allowed for higher operating temperatures (up to 120 °C) than standard splitters made of acrylate plastic (up to 80 °C). The splitters show optical losses lower than 4.0 dB at 532 nm/650 nm, 2.6 dB at 850 nm, 3.4 dB at 1300 nm and 5.1 dB at 1550 nm at room temperature. The optical losses measured in the thermal shock test chamber at temperatures up to 120 °C showed that the best sample had losses lower than 4.2 dB at 850/1300 nm, 4.6 dB at 532 nm and 7.6 dB at 650 nm. Such splitters would be very useful in places with elevated temperatures, for instance in engine parts where the expected temperature can reach as high as 120 °C.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Non-Destructive Characterization of Subsurface Residual Stress Fields and Correlation with Microstructural Conditions in a Shot-Peened Inconel Component

Shot-peening is an important surface treatment used in a preventative way to guard against fatigue failures. The residual stress state imparted by shot-peening deters the formation and propagation of surface cracks. In this paper, we describe the measurement of residual stresses in an Inconel, IN100, sample using lattice strains measured using High Energy X-ray Diffraction (HEXD) and a Bi-Scale Optimization Method (BSOM). HEXD enabled rapid, non-destructive lattice strain measurements over a large region of the sample. Subsurface strains were obtained using a conical slit setup. The BSOM utilizes a macroscale representation of the sample and a spherical harmonic-based crystal scale representation of crystal orientation space at each experimental point (diffraction volume). A roughly biaxial stress state was predicted with a von Mises equivalent stress between 300 MPa and 400 MPa near the surface. The layer of material with high residual stress induced by shot-peening was found to be approximately 1 mm thick. Diffraction peak width, EBSD, and microhardness measurements were also made on the same sample, which rendered more qualitative measures of the plasticity-related effects of the shot-peening induced residual stress field. All of these measurements show a dimishing shot-peening plasticity with the increasing depth.

42 ENGINEERING↗
DOE OSTI2019

Emerging Role of Coronary Computed Tomography Angiography in Lipid-Lowering Therapy: a Bridge to Image-Guided Personalized Medicine

Purpose of Review: To summarize the current status of coronary computed tomography angiography (CTA) in the assessment of coronary plaques and discuss the ability of serial coronary CTA to quantitatively measure changes in the plaque burden in response to lipid-lowering therapy. Recent Findings: Recent advances in coronary CTA have allowed identification of high-risk coronary features in acute coronary syndrome and measurement of changes in the coronary plaque burden with good reproducibility. Statin therapy may delay plaque progression and change some plaque features. However, the clinical relevance of quantitative changes in coronary plaques and the optimal methods to reduce the plaque burden remain unclear. Summary: Despite guideline-directed lipid-lowering therapy, adverse events still occur in substantial numbers of patients receiving statins. Coronary CTA is noninvasive and has high diagnostic performance in patients with coronary artery disease, making change in the plaque burden an applicable biomarker for individualized assessment of future risk.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

MALDI Orbitrap Mass Spectrometry Profiling of Dysregulated Sulfoglycosphingolipids in Renal Cell Carcinoma Tissues

Matrix-assisted laser desorption/ionization coupled with Orbitrap mass spectrometry (MALDI-Orbitrap-MS) is used for the clinical study of patients with renal cell carcinoma (RCC), as the most common type of kidney cancer. Significant changes in sulfoglycosphingolipid abundances between tumor and autologous normal kidney tissues are observed. First, sulfoglycosphingolipid species in studied RCC samples are identified using high mass accuracy full scan and tandem mass spectra. Subsequently, optimization, method validation, and statistical evaluation of MALDI-MS data for 158 tissues of 80 patients are discussed. More than 120 sulfoglycosphingolipids containing one to five hexosyl units are identified in human RCC samples based on the systematic study of their fragmentation behavior. Many of them are recorded here for the first time. Multivariate data analysis (MDA) methods, i.e., unsupervised principal component analysis (PCA) and supervised orthogonal partial least square discriminant analysis (OPLS-DA), are used for the visualization of differences between normal and tumor samples to reveal the most up- and downregulated lipids in tumor tissues. Obtained results are closely correlated with MALDI mass spectrometry imaging (MSI) and histologic staining. Important steps of the present MALDI-Orbitrap-MS approach are also discussed, such as the selection of best matrix, correct normalization, validation for semiquantitative study, and problems with possible isobaric interferences on closed masses in full scan mass spectra. .

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2017

Application of Atmospheric Pressure Photoionization H/D-exchange Mass Spectrometry for Speciation of Sulfur-containing Compounds

Herein we report the observation of atmospheric pressure in-source hydrogen–deuterium exchange (HDX) of thiol group for the first time. The HDX for thiol group was optimized for positive atmospheric pressure photoionization (APPI) mass spectrometry (MS). The optimized HDX-MS was applied for 31 model compounds (thiols, thiophenes, and sulfides) to demonstrate that exchanged peaks were observed only for thiols. The optimized method has been successfully applied to the isolated fractions of sulfur-rich oil samples. The exchange of one and two thiol hydrogens with deuterium was observed in the thiol fraction; no HDX was observed in the other fractions. Thus, the results presented in this study demonstrate that the HDX-MS method using APPI ionization source can be effective for speciation of sulfur compounds. This method has the potential to be used to access corrosion problems caused by thiol-containing compounds. .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗