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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 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Machine learning for automated experimentation in scanning transmission electron microscopy

Abstract Machine learning (ML) has become critical for post-acquisition data analysis in (scanning) transmission electron microscopy, (S)TEM, imaging and spectroscopy. An emerging trend is the transition to real-time analysis and closed-loop microscope operation. The effective use of ML in electron microscopy now requires the development of strategies for microscopy-centric experiment workflow design and optimization. Here, we discuss the associated challenges with the transition to active ML, including sequential data analysis and out-of-distribution drift effects, the requirements for edge operation, local and cloud data storage, and theory in the loop operations. Specifically, we discuss the relative contributions of human scientists and ML agents in the ideation, orchestration, and execution of experimental workflows, as well as the need to develop universal hyper languages that can apply across multiple platforms. These considerations will collectively inform the operationalization of ML in next-generation experimentation.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Improving Electronic Conductivity of Layered Oxides through the Formation of Two-Dimensional Heterointerface for Intercalation Batteries

Synthetic strategies for the improvement in electronic conductivities and electrochemical stabilities of transition metal oxide cathodes, which are limiting factors in the performance of commercial intercalation batteries, are required for next-generation, high-performance battery systems. Furthermore, the chemical preintercalation approach, consisting of a combined sequence of a sol–gel process, extended aging, and a hydrothermal treatment, is a versatile, wet synthesis technique that allows for the incorporation of a polar species between the layers of transition metal oxides. Here, formation of a layered 2D δ-C x V 2 O 5 · n H 2 O heterostructure occurs via chemical preintercalation of dopamine molecules between bilayers of vanadium oxide followed by the hydrothermal treatment of the precipitate, leading to carbonization of the organic molecules. The presence of carbon layers within the structure has been confirmed via a combined analysis of scanning electron microscopy, X-ray diffraction, thermogravimetric analysis, Raman spectroscopy, X-ray photoelectron spectroscopy, electrochemical impedance spectroscopy, four-probe conductivity measurements, and scanning transmission electron microscopy characterization. 2D δ-C x V 2 O 5 · n H 2 O heterostructure electrodes demonstrated significantly improved electrochemical performance, particularly at higher current densities, in Li-ion cells. The heterostructure electrodes exhibited 75% of the capacity retention when the current was changed from 20 mA g –1 (206 mAh g –1 ) to 300 mA g –1 (155 mAh g –1 ), while the reference δ-V 2 O 5 · n H 2 O electrodes exhibited only 10% capacity retention in the same experiment. Remarkably, 2D δ-C x V 2 O 5 · n H 2 O heterostructure electrodes demonstrated significantly improved capacity retention (94% after 30 cycles) for bilayered vanadium oxide electrodes in Li-ion cells during galvanostatic cycling at 20 mA g –1 . The improved electrochemical performance, in both extended cycling and rate capability studies, of the 2D δ-C x V 2 O 5 · n H 2 O heterostructure electrodes in the Li-ion system is ascribed to the intermittent formation of carbon layers within the bilayered structure, which leads to increased electronic conductivity and improved structural stability of the heterostructure compared to the reference δ-V 2 O 5 · n H 2 O electrodes.

25 ENERGY STORAGE↗
DOE OSTI2025

Designing Antifouling and Antimicrobial Interfaces: Structural Characterization using CryoEM, Automated Microscopy, and AI Image Segmentation

The design of functionalized surfaces for interactions with biological systems is critical across sectors such as healthcare, energy, and agriculture. Tailoring materials for specific applications, such as antifouling and antimicrobial surfaces, demands a comprehensive understanding of topology and chemistry across multiple length and time scales on both biological and materials systems. This work presents the development and characterization of nanostructured surfaces with controlled topographies and chemistries that enhance bacterial membrane disruption, reduce biofilm formation, and improve antimicrobial and antifouling capabilities. Two specific use cases will be presented - the use of cellulose nanocrystals (CNCs) for bacterial growth inhibition and the development of antifouling surfaces to prevent protein and bacterial adsorption [1-4]. By leveraging large language models (LLMs) for image segmentation and training [5], we enable automated analysis of terabyte-scale cryogenic electron microscopy (cryoEM) datasets. This analysis provides statistical insights into the biotic/abiotic interface and facilitates automated electron microscopy experiments to mitigate time and dose. The integration of cryogenic electron tomography (cryoET) and cryogenic focused ion beam (cryoFIB) milling enables high-resolution, near-native-state imaging and 3D reconstructions of bio/material interfaces [6]. Orthogonal characterization techniques and computational modeling further enhances our understanding, offering a robust platform for the design and optimization of next-generation functional surfaces [7].

Williams, Alexis [ORNL] (ORCID:0000000252835822)↗
DOE OSTI2018

Adsorption Efficiency of Polyaspartate-Montmorillonite Composite Towards the Removal of Pb(II) and Cd(II) from Aqueous Solution

The selective modification of sodium montmorillonite (Na{sup +}-Mt) surface with polyionene followed by poly (succinimde-co-aspartate) has been considered. Na{sup +}-Mt was allowed to react with well characterized polyionene in two fold excess. The resulting polyionene/Mt (IC) was further modified with poly (succinimide-co-aspartate) through an ion exchange process. The obtained polyaspartate/Mt (IPS) composite was characterized by elemental analysis, X-ray diffraction, FTIR spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), and BET surface analyzer. The adsorption efficiency of IPS composite was investigated for the removal of Pb(II) and Cd(II) from aqueous solution under different experimental conditions including initial metal ions concentration, temperature and single and binary mixture systems of metal ions. The experimental data were analyzed by Langmuir, Freundlich, Temkin, and Dubinin-Radushkevich models. Langmuir model reveals that the monolayer adsorption capacity of IPS was 92.59 and 67.57 mg/g for Pb(II) and Cd(II), respectively. The modification of parent Na{sup +}-Mt enhanced their adsorption capacity by about 87.91 and 29.84% for Pb(II) and Cd(II), respectively, due to inclusion of extra active sites of polyaspartate. The mean sorption energy, E calculated from Dubinin–Radushkevich isotherm were 2.75 and 1.98 kJ/mol for the adsorption of Pb(II) and Cd(II), respectively, indicating physical adsorption process. Also, The thermodynamic parameters were calculated and indicated that the adsorption was spontaneous and exothermic process. The mechanism of cation exchange and complexation of metal ions was suggested. IPS composite has a considerable potential for the removal of heavy metal ions from aqueous solution and wastewater stream.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Comparison of direct transesterification of algal biomass under supercritical methanol and microwave irradiation conditions

In this comparative study, direct conversion of algal biomass into biodiesel using supercritical methanol (SCM) and microwave-assisted (MW) transesterification methods was investigated. Wet algal biomass was used as feedstock in the supercritical methanol process and dry algal biomass for the microwaveassisted transesterification. Experimental runs were designed using a response surface methodology and the process parameters such as wet/dry algae to methanol ratio, reaction temperature, reaction time and catalyst concentrations were optimized for both processes. The microwave-assisted approach improves extractions of algae significantly, with a higher efficiency, reduced extractive- ransesterification time and increased yield. While the non-catalytic supercritical methanol method produces highly purified extracts (free of harmful solvents and catalyst residues), and reduces energy consumption in separation and purification steps. The algal biodiesel samples from SCM and MW processes were compared using FT-IR and TGA analysis methods to identify the functional group attributions and thermal stability of the biofuel samples, respectively. The transmission electron microscopy (TEM) analysis of algal biomass and lipid extracted algae (LEA) and energy requirements for the two processes are also presented.

09 BIOMASS FUELS↗
DOE OSTI2016

Using nonequilibrium dynamics to probe competing orders in a Mott-Peierls system

Competition between ordered phases, and their associated phase transitions, are significant in the study of strongly correlated systems. Here, we examine one aspect, the nonequilibrium dynamics of a photoexcited Mott-Peierls system, using an effective Peierls-Hubbard model and exact diagonalization. Near a transition where spin and charge become strongly intertwined, we observe antiphase dynamics and a coupling-strength-dependent suppression or enhancement in the static structure factors. The renormalized bosonic excitations coupled to a particular photoexcited electron can be extracted, which provides an approach for characterizing the underlying bosonic modes. The results from this analysis for different electronic momenta show an uneven softening due to a stronger coupling near k F . As a result, this behavior reflects the strong link between the fermionic momenta, the coupling vertices, and ultimately, the bosonic susceptibilities when multiple phases compete for the ground state of the system.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1994

Relativistic electron acceleration and decay time scales in the inner and outer radiation belts: SAMPEX

High-energy electrons have been measured systematically in a low-altitude (520 x 675 km), nearly polar (inclination = 82 deg) orbit by sensitive instruments onboard the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX). Count rate channels with electron energy thresholds ranging from 0.4 MeV to 3.5 MeV in three different instruments have been used to examine relativistic electron variations as a function of L-shell parameter and time. A long run of essentially continuous data (July 1992 - July 1993) shows substantial acceleration of energetic electrons throughout much of the magnetosphere on rapid time scales. This acceleration appears to be due to solar wind velocity enhancements and is surprisingly large in that the radiation belt 'slot' region often is filled temporarily and electron fluxes are strongly enhanced even at very low L-values (L aprroximately 2). A superposed epoch analysis shows that electron fluxes rise rapidly for 2.5 is approximately less than L is approximately less than 5. These increases occur on a time scale of order 1-2 days and are most abrupt for L-values near 3. The temporal decay rate of the fluxes is dependent on energy and L-value and may be described by J = Ke-t/to with t(sub o) approximately equals 5-10 days. Thus, these results suggest that the Earth's magnetosphere is a cosmic electron accelerator of substantial strength and efficiency.

Baker, D. N.↗
NASA NTRS1999

Miniature Time-of-Flight Mass Spectrometer

Major advances must occur to protect astronauts from prolonged periods in near-zero gravity and high radiation associated with extended space travel. The dangers of living in space must be thoroughly understood and methods developed to reverse those effects that cannot be avoided. Six of the seven research teams established by the National Space Biomedical Research Institute (NSBRI) are studying biomedical factors for prolonged space travel to deliver effective countermeasures. To develop effective countermeasures, each of these teams require identification of and quantitation of complex pharmacological, hormonal, and growth factor compounds (biomarkers) in humans and in experimental animals to develop an in-depth knowledge of the physiological changes associated with space travel. At present, identification of each biomarker requires a separate protocol. Many of these procedures are complicated and the identification of each biomarker requires a separate protocol and associated laboratory equipment. To carry all of this equipment and chemicals on a spacecraft would require a complex clinical laboratory; and it would occupy much of the astronauts time. What is needed is a small, efficient, broadband medical diagnostic instrument to rapidly identify important biomarkers for human space exploration. The Miniature Time-Of- Flight Mass Spectrometer Project in the Technology Development Team is developing a small, high resolution, time-of-flight mass spectrometer (TOFMS) to quantitatively measure biomarkers for human space exploration. Virtues of the JHU/APL TOFMS technologies reside in the promise for a small (less than one cubic ft), lightweight (less than 5 kg), low-power (less than 50 watts), rugged device that can be used continuously with advanced signal processing diagnostics. To date, the JHU/APL program has demonstrated mass capability from under 100 to beyond 10,000 atomic mass units (amu) in a very small, low power prototype for biological analysis. Further, the electronic nature of the TOFMS output makes it ideal for rapid telemetry to earth for in-depth analysis by ground support teams.

Potember, Richard S.↗
DOE OSTI2022

The Complexity and Challenges of Irradiation-Induced Phase Instability Phenomenon in Nuclear Power Plant Components

High energy irradiation by neutrons or ions of metastable austenitic 300-series steels appears to initiate formation of bcc-phases with different morphology and elemental composition compared to that of retained ferrite. Extensive formation of specific Fe-rich ferrite was observed on the grain boundaries of annealed Russian steel 12Cr18Ni10Ti, an analog of AISI 321, after irradiation in the center-core region of sodium-cooled BN-350 fast reactor (SFR) doses up to 57 dpa at ~1×10-6dpa/sec. The ferrite fraction determined from scanning electron microscopy (SEM) closely matched the magnetic fraction determined using a ferritscope confirmed by X-ray diffraction analysis and selected area diffraction patterns. Chemical composition of the secondary phases was determined by energy dispersive X-ray analysis using transmission electron microscope, showing Fe-rich ferrite domains. Fe-ion irradiation (2.3 MeV) was used to study the accumulation of ferrite and martensite phases at higher dpa rates. The very high etchability of these ferrite particles in alcohol-based solutions may signal a very high etching in hot water, leading to accelerated intergranular cracking, especially upon long-term exposure during extended plant lifetimes.

D a, Merezhko↗
DOE OSTI2016

Computational algorithms for analysis of data from thin-film thermoresistors on a radio-electronic printed circuit board

In the paper, the data analysis is considered for thin-film thermoresistors coated on to a radio-electronic printed circuit board to determine possible zones of its overheating. A mathematical model consists in an underdetermined system of linear algebraic equations with an infinite set of solutions. For computing a more real solution, two additional conditions are used: the smoothness of a solution and the positiveness of an increase of temperature during overheating. Computational experiments demonstrate that an overheating zone is determined exactly with a tolerable accuracy of temperature in it.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2016

Chemical synthesis and characterization of PdTe-Ag{sub 2}Te nanowires heterostructure

Ag{sub 2}Te and Pd doped Ag{sub 2}Te nanowires are synthesized using chemical route. Field Emission Scanning Electron Microscopy (FESEM) shows the presence of nanowires of nearly few micron length and ~ 200 nm diameter. The composition analysis performed using Electron Dispersive Spectroscopy (EDS) shows the presence of almost 1.98 at% palladium. Reitveld refinement of X-ray diffraction (XRD) shows the presence of 0.3 % of PdTe phase in addition to Ag{sub 2}Te in Pd doped Ag{sub 2}Te sample.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2024

Observation of halogen-like behavior of gold in fluorinated bimetallic CoAuF 1-2 − and CuAuF 1-2 − clusters: Anion photoelectron spectroscopy and density functional theory

Using size-selected anion photoelectron spectroscopy and density functional theory, we investigated the structures and properties of fluorinated bimetallic clusters CoAuF 1-2 − and CuAuF 1-2 − and their neutrals. Both experimental and theoretical results show that in these cluster anions, Au behaves like a halogen atom. For example, the measured vertical detachment energies (VDEs) of CoAuF − (2.00 ± 0.08 eV) and CuAuF − (3.8 ± 0.1 eV) are close to those of CoF 2 − (2.12 ± 0.08 eV) and CuF 2 − (3.58 ± 0.08 eV), respectively. The theoretical results show that the geometries and electronic structures of CoAuF − and CuAuF − are similar to those of CoF 2 − and CuF 2 − . The natural population analysis and natural electron configuration analyses further confirm that the electronic properties of Au in MAuF − (M = Co, Cu) mimic those of MF 2 − . In addition, the electron localization function analyses show that the M-Au chemical bonds are similar to the corresponding M-F chemical bonds, providing evidence for the ionic nature of the interactions. When a second F atom is attached to the CoAuF − and CuAuF − clusters, the VDEs of the resulting CoAuF 2 − and CuAuF 2 − are 4.38 ± 0.08 eV and 3.71 ± 0.08 eV, respectively, indicating their superhalogen character as these values are higher than those of halogen anions. The results may be useful for understanding the properties of gold at the nanoscale that play an important role in catalysis and nanotechnology.

Ab-initio methods↗
DOE OSTI2019

Practical Challenges and Failure Modes During Fabrication of Haynes 230 Micro-Pin Solar Receivers for High Temperature Supercritical Carbon Dioxide Operation

Printed circuit heat exchangers (PCHX) fabricated from high nickel alloys have shown promise as primary heat exchangers, recuperators, and solar receivers for high temperature and pressure supercritical carbon dioxide power cycles. There are numerous challenges in fabricating these devices including forming channel features, joining via diffusion or transient liquid phase bonding, and brazing/welding of headers. Commercial entities are understandably hesitant to share propriety best practices, and both commercial and non-commercial entities working on these components tend not to publically share failures and mistakes. However, sharing of this information could prevent similar costly errors and further the understanding of the coupled manufacturing, materials and mechanics issues in creating these components. Thus, in this paper, we document the challenges, failures, and mitigation methods uncovered in fabrication of prototype micro-pin based solar thermal receivers constructed of Haynes 230 and fabricated through a combination of photochemical machining (PCM), wire electrical discharge machining (EDM), transient liquid phase (TLP) bonding, vacuum brazing, and gas tungsten arc welding (GTAW). The receiver is designed to absorb concentrated solar fluxes greater than 140 W cm-2, while heating supercritical carbon dioxide from 550 °C to 720 °C at a pressure of 20 MPa to 25 MPa. The prototype receiver consists of a thin (~ 450 µm), Haynes 230 coversheet bonded to a 15 cm × 15 cm Haynes 230 micro-pin plate. The pieces are joined using a TLP bonding process with a nickel-phosphorus interlayer. Prior to bonding, micro-pins with height ~150 µm and diameter 300 µm are fabricated using PCM in the plate, and through slot features are made using wire EDM. Finally, flow headers are joined to the microchannel plate through a combination of vacuum brazing and GTAW. During hydrostatic proof testing, the prototype device failed when the coversheet delaminated from the pin array at a pressure of 290 bar. A failure analysis including scanning electron microscopy (SEM) to view failure sites and energy-dispersive X-ray spectroscopy (EDS) to evaluate elemental analysis of the failed areas was conducted. The failure modes can be broadly categorized as (1) failures potentially relating to reliquification of the transient liquid phase bonds between the micro-pins plate and coversheet during post-processing, (2) failures related to manufacturing defects, and (3) failures attributed to design.

14 SOLAR ENERGY↗
NASA NTRS1977

Apparatus for measuring the force of gravity on freely falling electrons

An apparatus and data analysis technique for measuring the gravitational force on freely falling electrons are described. The measurement required that all forces acting on the electrons be uniform and measurable to about ten to the negative 11th power eV/m. The electrical force along the axis of the 5-cm-diam, vertical copper tube used in the experiment was found to be about six times ten to the negative 11th power eV/m when the tube was cooled to 4.2 K. Forces on electrons due to magnetic field gradients were reduced well below the electrical ones by selecting only ground state electrons for measurement. The absence, at 4.2 K, of much stronger electric fields, which were expected to arise from the patch effect and from differential lattice components, contrasts strongly with measurements of electric fields near metal surfaces made at room temperature.

Witteborn, F. C.↗
DOE OSTI2024

Angular analysis of B → K * e + e − in the low- q 2 region with new electron identification at Belle

We perform an angular analysis of the B → K * e + e − decay for the dielectron mass squared, q 2 , range of 0.0008 – 1.1200 GeV 2 / c 4 using the full Belle dataset in the K * 0 → K + π − and K * + → K S 0 π + channels, incorporating new methods of electron identification to improve the statistical power of the dataset. This analysis is sensitive to contributions from right-handed currents from physics beyond the Standard Model by constraining the Wilson coefficients C 7 ( ′ ) . We perform a fit to the B → K * e + e − differential decay rate and measure the imaginary component of the transversality amplitude to be A T Im = − 1.27 ± 0.52 ± 0.12 , and the K * transverse asymmetry to be A T ( 2 ) = 0.52 ± 0.53 ± 0.11 , with F L and A T Re fixed to the Standard Model values. The resulting constraints on the value of C 7 ′ are consistent with the Standard Model within a 2 σ confidence interval. Published by the American Physical Society 2024

Ferlewicz, D. (ORCID:0000000243741234)↗
NASA NTRS2012

Miniature Variable Pressure Scanning Electron Microscope for In-Situ Imaging and Chemical Analysis

NASA Marshall Space Flight Center (MSFC) is leading an effort to develop a Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) for in-situ imaging and chemical analysis of uncoated samples. This instrument development will be geared towards operation on Mars and builds on a previous MSFC design of a mini-SEM for the moon (funded through the NASA Planetary Instrument Definition and Development Program). Because Mars has a dramatically different environment than the moon, modifications to the MSFC lunar mini-SEM are necessary. Mainly, the higher atmospheric pressure calls for the use of an electron gun that can operate at High Vacuum, rather than Ultra-High Vacuum. The presence of a CO2-rich atmosphere also allows for the incorporation of a variable pressure system that enables the in-situ analysis of nonconductive geological specimens. Preliminary testing of Mars meteorites in a commercial Environmental SEM(Tradmark) (FEI) confirms the usefulness of lowcurrent/low-accelerating voltage imaging and highlights the advantages of using the Mars atmosphere for environmental imaging. The unique capabilities of the MVP-SEM make it an ideal tool for pursuing key scientific goals of NASA's Flagship Mission Max-C; to perform in-situ science and collect and cache samples in preparation for sample return from Mars.

Gaskin, Jessica A.↗
DOE OSTI2015

Oxidation and alpha-case formation in Ti–6Al–2Sn–4Zr–2Mo alloy

Isothermal heat treatments in ambient air were performed on wrought Ti–6Al–2Sn–4Zr–2Mo (Ti-6242) material at 500, 593 and 700°C for times up to 500 h. In the presence of oxygen at elevated temperatures simultaneous reactions occurred in Ti-6242 alloy, which resulted in the formation of an oxide scale and a layer with higher oxygen concentration (termed as alpha-case). Total weight gain analysis showed that there was a transition in the oxidation kinetics. At 500°C, the oxidation kinetics obeyed a cubic relationship up to 200 h and thereafter changed to parabolic at prolonged exposure times. At 593°C, it followed a parabolic relationship. After heat treatment at 700°C, the oxidation obeyed a parabolic relationship up to 200 h and thereafter changed to linear at prolonged exposure times. The observed transition is believed to be due to the differences observed in the oxide scale. The activation energy for parabolic oxidation was estimated to be 157 kJ/mol. In addition, alpha-case layer was evaluated using optical microscope, electron probe micro-analyser and microhardness tester. The thickness of the alpha-case layer was found to be a function of temperature and time, increasing proportionally, and following a parabolic relationship. The activation energy for the formation of alpha-case layer was estimated to be 153 kJ/mol. - Highlights: • Transition in oxidation kinetics was observed in Ti–6Al–2Sn–4Zr–2Mo alloy in the temperature range 500–700°C. • The activation energy for parabolic oxidation and for alpha-case formation is about 157 kJ/mol and 153 kJ/mol. • Thickness of alpha-case layer estimated by optical microscopy and electron probe microanalysis is comparable.

36 MATERIALS SCIENCE↗
NASA NTRS1973

Electrostatic Propulsion Beam Divergence Effects on Spacecraft Surfaces. Volume 2, Addendum 1: Ion Time-of-flight Determinations of Doubly to Singly Ionized Mercury Ion Ratios from a Mercury Electron Bombardment Discharge

The analysis of ion exhaust beam current flow for multiply charged ion species and the application to propellant utilization for the thruster are discussed. The ion engine in use in the experiments is a twenty centimeter diameter electromagnet electron bombardment engine. The experimental technique to determine the multiply charged ion abundance ratios using ion time of flight is described. An analytical treatment of the discharge action in producing various ion species has been carried out.

Sellen, J. M., Jr.↗