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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 289 records · Page 16
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Experimental and Theoretical Investigations of Magnetic Properties of Co Ferrite/Polyvinyl Alcohol Nanocomposites

Cobalt ferrite nanoparticles (NPs) have been synthesized by the modified co-precipitation technique in the presence of the polyvinyl alcohol (PVA) matrix. The structural and magnetic properties of NPs are tunable by means of interaction between the polymer and the surface of NPs. Magnetic properties of NPs were simulated using the accurate Monte Carlo (MC) method. In addition, the magnetic anisotropy constant has been obtained by means of the law of approach to saturation magnetization (LAS). The experimental and theoretical results are in good agreement with each other and show that the as-synthesized NPs are single domain and approximately non-interacting. The anisotropy constant and size of the NPs increase by increasing the concentration of precursors in the reaction medium. Nanocomposites have been characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Hysteresis loops were investigated at room temperature using a vibrating sample magnetometer (VSM). The crystallite size of single-domain NPs is lower than 20 nm, and the obtained results from FT-IR confirmed the interaction between PVA and the surface of the particles. These approximately non-interacting NPs are useful for magnetic data storage.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2025

Uncertainty in inventories for life cycle assessment: State‐of‐the‐art, challenges, and new technologies

Uncertainty is a critical factor that can hinder the quality and potential applications of life cycle assessment (LCA) results. A prominent source of uncertainty stems from the life cycle inventory (LCI) data. Various methodologies exist to estimate the uncertainty associated with LCI data, primarily based on the widely used structured pedigree matrix approach or the computationally intensive Monte Carlo simulation. This perspective review explores how new technologies (e.g., computational algorithms and data collection methods) from data science and related fields can contribute to identifying, quantifying, and reducing uncertainty in LCI modeling. A brief overview of the sources of uncertainty in LCI modeling and how they are addressed in current LCA practice is provided. Additionally, several new technologies are identified, and the potential benefits of their implementation in reducing uncertainties in LCI modeling are discussed. This perspective review concludes by identifying potential areas that require further development for these technologies.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2025

AAPM Truth‐based CT (TrueCT) reconstruction grand challenge

Background: This Special Report summarizes the 2022, AAPM grand challenge on Truth-based CT image reconstruction. Purpose: To provide an objective framework for evaluating CT reconstruction methods using virtual imaging resources consisting of a library of simulated CT projection images of a population of human models with various diseases. Methods: Two hundred unique anthropomorphic, computational models were created with varied diseases consisting of 67 emphysema, 67 lung lesions, and 66 liver lesions. The organs were modeled based on clinical CT images of real patients. The emphysematous regions were modeled using segmentations from patient CT cases in the COPDGene Phase I dataset. For the lung and liver lesion cases, 1–6 malignant lesions were created and inserted into the human models, with lesion diameters ranging from 5.6 to 21.9 mm for lung lesions and 3.9 to 14.9 mm for liver lesions. The contrast defined between the liver lesions and liver parenchyma was 82 ± 12 HU, ranging from 50 to 110 HU. Similarly, the contrast between the lung lesions and the lung parenchyma was defined as 781 ± 11 HU, ranging from 725 to 805 HU. For the emphysematous regions, the defined HU values were −950 ± 17 HU ranging from −918 to −979 HU. The developed human models were imaged with a validated CT simulator. The resulting CT sinograms were shared with the participants. The participants reconstructed CT images from the sinograms and sent back their reconstructed images. Further, the reconstructed images were then scored by comparing the results against the corresponding ground truth values. The scores included both task-generic (root mean square error [RMSE] and structural similarity matrix [SSIM]), and task-specific (detectability index [d’] and lesion volume accuracy) metrics. For the cases with multiple lesions, the measured metric was averaged across all the lesions. To combine the metrics with each other, each metric was normalized to a range of 0 to 1 per disease type, with “0” and “1” being the worst and best measured values across all cases of the disease type for all received reconstructions. Results: The True-CT challenge attracted 52 participants, out of which 5 successfully completed the challenge and submitted the requested 200 reconstructions. Across all participants and disease types, SSIM absolute values ranged from 0.22 to 0.90, RMSE from 77.6 to 490.5 HU, d’ from 0.1 to 64.6, and volume accuracy ranged from 1.2 to 753.1 mm3. The overall scores demonstrated that participant “A” had the best performance in all categories, except for the metrics of d’ for lung lesions and RMSE for liver lesions. Participant “A” had an average normalized score of 0.41 ± 0.22, 0.48 ± 0.32, and 0.42 ± 0.33 for the emphysema, lung lesion, and liver lesion cases, respectively. Conclusions: The True-CT challenge successfully enabled objective assessment of CT reconstructions with the unique advantage of access to a diverse population of diseased human models with known ground truth. This study highlights the significant potential of virtual imaging trials in objective assessment of medical imaging technologies.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Nanosized carriers for hydrophobic compounds based on mesoporous silica: synthesis and adsorption properties

MCM-41 type mesoporous silica particles were obtained using a template method in an alkaline medium and cetyltrimethylammonium bromide as a matrix. The structural and adsorption characteristics of the mesoporous material were studied by dynamic light scattering, scanning electron microscopy, low-temperature adsorption—desorption of nitrogen, IR spectroscopy, and simultaneous thermal analysis. It was shown that the obtained mesoporous material possesses high porosity with the specific pore volume in excess of 1 cm{sup 3} g{sup −1}. It was established that the size of silica particles does not exceed 200 nm, which is a value acceptable for the penetration of drugs through cell membranes. The optimal compositions of aqueous dispersions of MCM-41 with minimal sedimentation processes were determined. A drug (indomethacin) was encapsulated into the silica pores using the precipitation method at various temperatures (40 and 60 °C), the quantitative parameters of loading efficiency were calculated. The infl uence of temperature on the encapsulation ability was demonstrated.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

Microstructure and hardness evolution induced by annealing of ion irradiated LiTaO 3

We report the evolution of the microstructure and mechanical properties of low-energy heavy-ion-irradiated LiTaO 3 crystals annealed at various temperatures was investigated by transmission electron microscopy (TEM) observations and nanoindentation tests to extend the applications of irradiated LiTaO 3 crystals. Before annealing, randomly distributed voids formed in an approximately 200 nm thick region at the end of the ion irradiation range, which was attributed to preferential absorption of interstitials by the amorphous-crystalline interface. After annealing, a new directional diffusion path of defects was identified, resulting in a void string. Furthermore, void string diffusion to the free surface was also found during the annealing temperature increase process, which offers a potential application in designing custom sized-thickness exfoliation at the nanoscale. Meanwhile, two competing processes were identified during the annealing process: epitaxial recrystallization from the amorphous-crystalline interface and grain nucleation process in the amorphous region, which formed phases different from the matrix crystal structure, resulting in an interaction between them. Furthermore, the hardness of irradiated samples was also found to be affected by the annealing process; in particular, a hardness decrease induced by the interstitial Fe ions in the recrystallized region was also confirmed, which can improve the processability of samples for further application.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Evaluation of AGR-3/4 In-pile Silver Release Predictions Against Post-Irradiation Examination Measurements

Fuel performance modeling codes that accurately predict the transport of radionuclides in high-temperature gas-cooled reactors that utilize tristructural isotopic (TRISO) fuel particles are an important aspect of reactor safety analyses. One objective of the Advanced Gas Reactor (AGR)-3/4 experiment was to assess the transport of fission products through fuel particles and their subsequent release into the compact matrix and structural graphite materials. This was accomplished by irradiating uranium oxycarbide (UCO) driver fuel particles and designed-to-fail (DTF) particles to serve as known sources of fission products. The fission product of particular interest when it comes to such transport is silver (Ag-110 m), as it has a 250-day half-life and has relatively high mobility in the TRISO coating layers. Furthermore, to assess the current modeling capabilities and diffusion parameters employed in the fuel performance codes PARFUME and BISON, the fractional release of silver release predicted by the two codes were compared against post-irradiation examination measurements from the AGR-3/4 experiment.

AGR-3/4 Experiment↗
DOE OSTI2013

Diffusion mediated agglomeration of CdS nanoparticles via Langmuir–Blodgett technique

Graphical abstract: - Highlights: • Diffusion mediated agglomeration of CdS nanoparticles are discussed. • Formation of CdS nanoparticles are confirmed by the change of chain length in XRD. • AFM shows the agglomeration of particles with a film swelling of about 5 Å. • UV–vis absorbance suggests that the grown particles show quantum confinement. • Hexagonal form of particle was confirmed by UV–vis reflectivity. - Abstract: We have reported a diffusion mediated agglomeration of cadmium sulphide (CdS) nanoparticles within cadmium arachidate (CdA{sub 2}) film matrix. The structural morphology and formation of CdS nanoparticles are characterized by X-ray diffraction (XRD), X-ray reflectivity (XRR), atomic force microscopy (AFM) and ultraviolet-visible spectroscopy techniques. X-ray diffraction (XRD) results show a change in bilayer difference from 53.04 Å to 43 Å after the sulphidation. An epitaxial growth of the films by ∼5 Å after sulphidation is confirmed from atomic force microscopy studies. The particle size calculated form UV–vis absorption edges are found to be varying from 2.6 nm to 3.3 nm for the different layers. A lateral dimension of 72–80 nm from AFM measurements and a size of 2.6–3.3 nm have confirmed one side flat pseudo two-dimensional disk-like nanoparticles. UV–vis reflectivity peak at E{sub 1} (A) confirms the formation of hexagonal CdS nanoparticles along the c-axis.

36 MATERIALS SCIENCE↗
DOE OSTI2013

Carbon nanotube based pressure sensor for flexible electronics

Highlights: • The electromechanical change of vertically aligned carbon nanotubes. • Fabrication of CNT field-effect transistor on flexible substrate. • CNT based FET integrated active pressure sensor. • The integrated device yields an increase in the source-drain current under pressure. - Abstract: A pressure sensor was developed based on an arrangement of vertically aligned carbon nanotubes (VACNTs) supported by a polydimethylsiloxane (PDMS) matrix. The VACNTs embedded in the PDMS matrix were structurally flexible and provided repeated sensing operation due to the high elasticities of both the polymer and the carbon nanotubes (CNTs). The conductance increased in the presence of a loading pressure, which compressed the material and induced contact between neighboring CNTs, thereby producing a dense current path and better CNT/metal contacts. To achieve flexible functional electronics, VACNTs based pressure sensor was integrated with field-effect transistor, which is fabricated using sprayed semiconducting carbon nanotubes on plastic substrate.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Sol–gel synthesis, structure and luminescence properties of Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors

Graphical abstract: The phosphor powders of Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} were prepared by sol–gel method. The dependence of luminescence intensity on the Eu{sup 3+} concentration was investigated. - Highlights: • We synthesize Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors by the sol–gel method. • The effect of temperature on the crystallinity and morphology is investigated. • The phosphor presents an intense CT band in near UV range (370–410 nm). • The concentration quenching mechanism is the exchange interaction. - Abstract: Double-perovskite Ba{sub 2}Zn{sub 1−x}MoO{sub 6}:xEu{sup 3+} (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) orange–red emitting phosphors were synthesized by using the sol–gel method. The crystalline structure and photoluminescence properties of the phosphors were investigated. The X-ray diffraction (XRD) patterns indicate that the structure of matrix Ba{sub 2}ZnMoO{sub 6} is cubic double-perovskite with space group Fm-3m. The Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors present an intense broad charge transfer (CT) band absorption in near UV range (370–410 nm), which attributes to the charge transfer state of MoO{sub 6}, and performs orange–red emission of Eu{sup 3+} ({sup 5}D{sub 0} → {sup 7}F{sub 1} transition) at around 596 nm. A low concentration quenching occurs in Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} and the optimal doping concentration is about 6 mol%. The Ba{sub 2}ZnMoO{sub 6}:Eu{sup 3+} phosphors are considered to be a promising orange–red emitting phosphor for near ultraviolet GaN-based white light emitting diode.

36 MATERIALS SCIENCE↗
DOE OSTI2026

In situ studies on heavy ion irradiation and partial oxidation induced stacking faults and nanograins in tungsten nanolaminates

Understanding the microstructural evolution of tungsten (W) under extreme irradiation environments is critical for its application as a plasma-facing material in future fusion reactors. Heavy ion irradiation study offers expedited damage accumulation and thus allows irradiation tolerance property prediction in a short period of time. In this study we explore in situ Kr ion irradiation of W nanolaminates at 800 °C and uncover a complex interplay of irradiation-induced transformations, including the emergence of stacking faults, nanograin formation, and generation of thickened grain boundaries defined as GB regions with the thickness of up to 15 nm. High-resolution transmission electron microscopy studies reveal the formation of extended planar faults and a metastable hexagonal close-packed (hcp) phase within the body-centered cubic (bcc) matrix. These structural transitions are facilitated by irradiation-induced shear. They are further stabilized by the presence of oxygen, which promotes stacking fault formation and vacancy trapping. Elevated temperatures enhance defect mobility, enabling dynamic recrystallization into ultrafine grains and the thickening of GBs due to defect absorption and impurity segregation. These findings unravel non-equilibrium phase transformation pathways in heavy ion irradiated W and highlight the critical role of impurity-mediated defect dynamics in governing its radiation tolerance properties.

Wazeer, Adil [Purdue University]↗
DOE OSTI2021

Single-Step Direct Laser Writing of Multimetal Oxygen Evolution Catalysts from Liquid Precursors

We investigate a laser direct-write method to synthesize and deposit metastable, mixed transition metal oxides and evaluate their performance as oxygen evolution reaction catalysts. This laser processing method enabled the rapid synthesis of diverse heterogeneous alloy and oxide catalysts directly from cost-effective solution precursors, including catalysts with a high density of nanocrystalline metal alloy inclusions within an amorphous oxide matrix. The nanoscale heterogenous structures of the synthesized catalysts were consistent with reactive force-field Monte Carlo calculations. By evaluating the impact of varying transition metal oxide composition ratios, we created a stable Fe 0.63 Co 0.19 Ni 0.18 O x /C catalyst with a Tafel slope of 38.23 mV dec -1 and overpotential of 247 mV, a performance similar to that of IrO 2 . Synthesized Fe 0.63 Co 0.19 Ni 0.18 O x /C and Fe 0.14 Co 0.46 Ni 0.40 O x /C catalysts were experimentally compared in terms of catalytic performance and structural characteristics to determine that higher iron content and a less crystalline structure in the secondary matrix decreases the charge transfer resistance and thus is beneficial for electrocatalytic activity. Furthermore, this conclusion is supported by density-functional theory calculations showing distorted active sites in ternary metal catalysts are key for lowering overpotentials for the oxygen evolution reaction.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Spin and phonon anomalies in epitaxial self-assembled CoFe{sub 2}O{sub 4}-BaTiO{sub 3} multiferroic nanostructures

Temperature dependent magnetic and phonon anomalies in epitaxial self-assembled CoFe{sub 2}O{sub 4} (CFO) rods embedded in BaTiO{sub 3} (BTO) matrix nanostructures were investigated. The temperature dependence of A{sub 1}(2TO) phonon frequency of BTO indicates that the BTO matrix experiences structural transformations. The lattice strain produced during the structural transformations drives spin reorientation in CFO rods, resulting in anomalous changes of magnetization. Through correlating the phonon anomalies with the increase of in-plane spin ordering, we show the spin-phonon coupling induces the softening of A{sub 1g} and A{sub 1}(2TO) phonons. It suggests that spin strongly couples with lattice strain and phonons in this nanostructure.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2012

Architecture for interoperable software in biology

Understanding biological complexity demands a combination of high-throughput data and interdisciplinary skills. One way to bring to bear the necessary combination of data types and expertise is by encapsulating domain knowledge in software and composing that software to create a customized data analysis environment. To this end, simple flexible strategies are needed for interconnecting heterogeneous software tools and enabling data exchange between them. Drawing on our own work and that of others, we present several strategies for interoperability and their consequences, in particular, a set of simple data structures—list, matrix, network, table and tuple—that have proven sufficient to achieve a high degree of interoperability. We provide a few guidelines for the development of future software that will function as part of an interoperable community of software tools for biological data analysis and visualization.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2020

LDA + $U_{sc}$ calculations of phase relations in FeO

Using the LDA + $U_{sc}$ method, we present calculation phase relations of iron monoxides involving five polytypes in multiple spin-state configurations. In this work, the Hubbard parameter $\textit{U}$ is determined self-consistently simultaneously with the occupation matrix and structures at arbitrary pressures. The Hubbard parameter strongly depends on pressure, structure, and spin state. Comparison with experimental structural data indicates the LDA + $U_{sc}$ can predict structure, compression curves, phase relations, and transition pressures very well for the insulating $\textit{B}$1 and $\textit{iB}$8 states. However, it requires additional calculations using the Mermin functional that includes the electronic entropic contribution to the free energy to obtain an $\textit{nB}$8 metallic state and a consistent $\textit{iB}$8 to $\textit{nB}$8 insulator to metal transition pressure.

36 MATERIALS SCIENCE↗