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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

First-Principles Simulation of Beam-Induced Processes Underlying Atomic Manipulation in Electron Microscopes

The development of experimental methods and apparatuses capable of promoting atomically precise material manipulations holds great promise for realizing the ultimate limit of feature miniaturization in materials and devices. The ability to modify materials atom by atom is anticipated to usher in new technologies in areas as diverse as separation science, medicine, and quantum information science. Historically, scanning probe-based techniques have been the most prominent approaches in this space. However, these methods are best suited for the manipulation of surface-exposed regions of materials, as the strong perturbations required for bond scission are delivered most effectively to atoms in the near-proximity to the scanning probe. In contrast, convergent electron beams with energies tuned slightly below the threshold for inducing irreversible knock-on damage have recently been employed (within scanning transmission electron microscopy) to promote atomic-scale bond rearrangements in various beam-stable solids. Currently, however, the efficiency and selectivity of beam-induced atomic manipulation processes with focused electron beams are such that long irradiation times are required to induce a desired atomic rearrangement. With a better understanding of the underlying physics dictating the outcome of a given irradiation event, methods can be devised to improve the efficiency of these techniques so that their promise can be fully realized through widespread adoption.To this end, this Account details our recent efforts to develop and apply tractable first-principles simulation approaches for studying the response of materials to electric beam-like external electric potentials applied in real space. We briefly review the concepts and capabilities in the area of atomically precise materials manipulation and review the early demonstrations of accomplishments in this area, focusing on studies using scanned convergent electron beam probes in particular. We expound upon the depth of the challenge and identify critical shortcomings of theoretical methods that have previously been employed in the simulation of beam-induced processes. We then describe the computational methods that we have generalized from the concepts and tools most commonly applied to the study of molecular photochemistry and how our adaptations of these methods can be employed to capture the relevant dynamical phenomena for beam-induced processes ranging from the initial electron scattering to the ensuing multistate reactions. Here, we contextualize these methods within the current state of the art in this area, which has historically focused primarily on the simulation of inelastic image formation in the electron microscope for the purpose of interpreting the results of quantitative electron microscopy experiments. We demonstrate that the spatial distribution of state-specific excitation rates due to the presence of an external (probe) electric charge is inhomogeneous, such that irradiation at particular locations in materials can favor specific electronic transitions (and disallow others). In addition to the potential for excited-state reaction pathways to be accessed through the initial inelastic scattering of the tightly focused electron beam from the targeted atoms, we also identify favorable conditions for the electronically nonadiabatic evolution of the highly vibrationally excited system to open complex multistate reaction pathways. Implications of the early results for understanding the mechanisms and potential routes to improved efficiency and selectivity in beam-induced reactions are discussed. We conclude with a summary of the current state of theory and modeling capabilities in this area and provide our perspective on future directions for theoretical and experimental developments that we view as crucial to advancing the use of convergent electron beams in mode-specific, atomically precise platforms for direct-write materials modifications.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Transient Radiation-Induced Berkelium(III) and Californium(III) Redox Chemistry in Aqueous Solution

Despite the significant impact of radiation-induced redox reactions on the accessibility and lifetimes of actinide oxidation states, fundamental knowledge of aqueous actinide metal ion radiation chemistry is limited, especially for the late actinides. A quantitative understanding of these intrinsic radiation-induced processes is essential for investigating the fundamental properties of these actinides. We present here a picosecond electron pulse reaction kinetics study into the radiation-induced redox chemistry of trivalent berkelium (Bk(III)) and californium (Cf(III)) ions in acidic aqueous solutions at ambient temperature. New, and first of a kind, second-order rate coefficients are reported for the transient radical-induced reduction of Bk(III) and Cf(III) by the hydrated electron (eaq−) and hydrogen atom (H•), demonstrating significant reactivity (up to 1011M-1s-1) indicative of a preference of these metals to adopt divalent states. Additionally, we reportthe first-ever second-order rate coefficients for the transient radical-induced oxidation of these elements by reaction with hydroxyl (•OH) and nitrate (NO3•) radicals, which also exhibited fast reactivity (ca. 108 M-1s-1). Transient Cf(II), Cf(IV), and Bk(IV) absorption spectra are also reported. Overall, the presented data highlight the existence of rich, complex, intrinsic late actinide radiation-induced redox chemistry that has the potential to influence the findings of other areas of actinide science.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Hydrogen Bonding and Its Effect on the Orientational Dynamics of Water Molecules inside Polyelectrolyte Brush-Induced Soft and Active Nanoconfinement

Despite being the most ubiquitous compound on Earth, the fundamental properties of water are not fully understood, especially in nanoconfinement. Densely grafted polyelectrolyte (PE) molecules attain the configuration of a “brush”: these PE brushes, due to their ability to form hydrogen bonds (HBs) with water via the PE functional groups, act as a source of soft and active nanoconfinement for the brush-trapped water molecules. In this paper, we study the effects of PE brush-induced confinement on the structure, dynamics and energetics of the water-water and water-PE HBs. Our results indicate a significant weakening of the HBs from bulk to sparsely grafted to densely grafted brushes. i.e., by increasing the degree of brush-induced nanoconfinement. We explain that this weakening of water-water HBs is caused by the disruption of the extended network of water molecules within the brush-induced nanoconfinement. This is confirmed by performing a ring structure analysis of the water molecules, which yields a reduction in the average ring size at higher degrees of brush-induced nanoconfinement (i.e., at higher brush grafting densities). Furthermore, we investigate the role of HB on the orientational dynamics of the water molecules. Here, we observe that the rotational motion of the water molecules becomes sluggish inside the PE brushes. Recent findings have indicated that the water and counterions trapped in brush-induced nanoconfinement demonstrate structures (in combination with the PE functional group) analogous to that in “water-in-salt” electrolytes that have seen extensive recent uses for Li-ion battery applications. However, the rotational dynamics of water molecules inside the brush-induced nanoconfinement is found to be distinctly different from that of conventional “water-in-salt” electrolytes in absence of any confinement; therefore, the present study will provide the necessary platform towards conceptualizing polymer-based nanoconfinement for battery applications.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Unusual plastic strain-induced phase transformation phenomena in silicon

Pressure-induced phase transformations (PTs) in Si, the most important electronic material, have been broadly studied, whereas strain-induced PTs have never been studied in situ. Here, we reveal in situ various important plastic strain-induced PT phenomena. A correlation between the direct and inverse Hall-Petch effect of particle size on yield strength and pressure for strain-induced PT is predicted theoretically and confirmed experimentally for Si-I→Si-II PT. For 100 nm particles, the strain-induced PT Si-I→Si-II initiates at 0.3 GPa under both compression and shear while it starts at 16.2 GPa under hydrostatic conditions. The Si-I→Si-III PT starts at 0.6 GPa but does not occur under hydrostatic pressure. Pressure in small Si-II and Si-III regions of micron and 100 nm particles is ~5–7 GPa higher than in Si-I. For 100 nm Si, a sequence of Si-I → I + II → I + II + III PT is observed, and the coexistence of four phases, Si-I, II, III, and XI, is found under torsion. Retaining Si-II and single-phase Si-III at ambient pressure and obtaining reverse Si-II→Si-I PT demonstrates the possibilities of manipulating different synthetic paths. The obtained results corroborate the elaborated dislocation pileup-based mechanism and have numerous applications for developing economic defect-induced synthesis of nanostructured materials, surface treatment (polishing, turning, etc.), and friction.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Exacerbation of ozone-induced pulmonary and systemic effects by β 2 -adrenergic and/or glucocorticoid receptor agonist/s

Agonists of β 2 adrenergic receptors (β 2 AR) and glucocorticoid receptors (GR) are prescribed to treat pulmonary diseases. Since ozone effects are mediated through the activation of AR and GR, we hypothesized that the treatment of rats with relevant therapeutic doses of long acting β 2 AR agonist (LABA; clenbuterol; CLEN) and/or GR agonist (dexamethasone; DEX) would exacerbate ozone-induced pulmonary and systemic changes. In the first study, male 12-week-old Wistar-Kyoto rats were injected intraperitoneally with vehicle (saline), CLEN (0.004 or 0.02 mg/kg), or DEX (0.02 or 0.1 mg/kg). Since dual therapy is commonly used, in the second study, rats received either saline or combined CLEN + DEX (each at 0.005 or 0.02 mg/kg) one day prior to and on both days of exposure (air or 0.8ppm ozone, 4 hr/day x 2-days). In air-exposed rats CLEN, DEX or CLEN + DEX did not induce lung injury or inflammation, however DEX and CLEN + DEX decreased circulating lymphocytes, spleen and thymus weights, increased free fatty acids (FFA) and produced hyperglycemia and glucose intolerance. Ozone exposure of vehicle-treated rats increased bronchoalveolar lavage fluid protein, albumin, neutrophils, IL-6 and TNF-α. Ozone decreased circulating lymphocytes, increased FFA, and induced hyperglycemia and glucose intolerance. Drug treatment did not reverse ozone-induced ventillatory changes, however, lung effects (protein and albumin leakage, inflammation, and IL-6 increase) were exacerbated by CLEN and CLEN + DEX pre-treatment in a dose-dependent manner (CLEN > CLEN + DEX). Systemic effects induced by DEX and CLEN + DEX but not CLEN in air-exposed rats were analogous to and more pronounced than those induced by ozone. These data suggest that adverse air pollution effects might be exacerbated in people receiving LABA or LABA plus glucocorticoids.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Spin-orbit coupling induced demagnetization in Ni: Ab initio nonadiabatic molecular dynamics perspective

Spin-orbit coupling (SOC), which can induce spin flip during the relaxation of photoexcited charge carrier, plays a crucial role in spin dynamics. Here in this work, we have used time-domain ab initio nonadiabatic molecular dynamics (NAMD) method to study the SOC induced ultrafast demagnetization in Ni at 300K. The spin-diabatic representation using spin-polarized Kohn-Sham (KS) basis sets and spin-adiabatic representation using spinor basis sets have been applied, and both of them achieve demagnetization in Ni with a timescale around 100fs. The spin-diabatic representation suggests a picture that the electron-phonon coupling (EPC) provides direct energy relaxation channel among the same-spin states, while the SOC can induce spin flip. After photoexcitation, it is found the spin-minority electrons relax to the same-spin states rather than the opposite-spin states, since EPC is larger than SOC by one order of magnitude. By contrast, for the spin-majority electrons, spin flip occurs since there are no empty same-spin states as electron acceptor above the Fermi level. The different relaxation pathways for spin-majority and spin-minority electrons induce the demagnetization. The spin-adiabatic representation provides an Elliott-Yafet spin-phonon scattering picture. The SOC induced reduction of magnetic moment in Ni may induce magnon to drive further demagnetization. The ab initio NAMD simulation provides a critical angle to understand how the SOC and EPC affect demagnetization process in Ni.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Sepsis induces muscle atrophy by inhibiting proliferation and promoting apoptosis via PLK1‐AKT signalling

Abstract Sepsis and sepsis‐induced skeletal muscle atrophy are common in patients in intensive care units with high mortality, while the mechanisms are controversial and complicated. In the present study, the atrophy of skeletal muscle was evaluated in sepsis mouse model as well as the apoptosis of muscle fibres. Sepsis induced atrophy of skeletal muscle and apoptosis of myofibres in vivo and in vitro. In cell‐based in vitro experiments, lipopolysaccharide (LPS) stimulation also inhibited the proliferation of myoblasts. At the molecular level, the expression of polo‐like kinase 1 (PLK1) and phosphorylated protein kinase B (p‐AKT) was decreased. Overexpression of PLK1 partly rescued LPS‐induced apoptosis, proliferation suppression and atrophy in C2C12 cells. Furthermore, inhibiting the AKT pathway deteriorated LPS‐induced atrophy in PLK1‐overexpressing C2C12 myotubes. PLK1 was found to participate in regulating apoptosis and E3 ubiquitin ligase activity in C2C12 cells. Taken together, these results indicate that sepsis induces skeletal muscle atrophy by promoting apoptosis of muscle fibres and inhibiting proliferation of myoblasts via regulation of the PLK1‐AKT pathway. These findings enhance understanding of the mechanism of sepsis‐induced skeletal muscle atrophy.

Cao, Ying‐Ya↗
DOE OSTI2020

Use of virus‐induced gene silencing to characterize genes involved in modulating hypersensitive cell death in maize

Abstract Plant disease resistance proteins (R‐proteins) detect specific pathogen‐derived molecules, triggering a defence response often including a rapid localized cell death at the point of pathogen penetration called the hypersensitive response (HR). The maize Rp1‐D21 gene encodes a protein that triggers a spontaneous HR causing spots on leaves in the absence of any pathogen. Previously, we used fine mapping and functional analysis in a Nicotiana benthamiana transient expression system to identify and characterize a number of genes associated with variation in Rp1‐D21 ‐induced HR. Here we describe a system for characterizing genes mediating HR, using virus‐induced gene silencing (VIGS) in a maize line carrying Rp1‐D21 . We assess the roles of 12 candidate genes. Three of these genes, SGT1 , RAR1 , and HSP90 , are required for HR induced by a number of R‐proteins across several plant–pathogen systems. We confirmed that maize HSP90 was required for full Rp1‐D21 ‐induced HR. However, suppression of SGT1 expression unexpectedly increased the severity of Rp1‐D21 ‐induced HR while suppression of RAR1 expression had no measurable effect. We confirmed the effects on HR of two genes we had previously validated in the N. benthamiana system, hydroxycinnamoyltransferase and caffeoyl CoA O‐methyltransferase . We further showed the suppression the expression of two previously uncharacterized, candidate genes, IQ calmodulin binding protein ( IQM3 ) and vacuolar protein sorting protein 37 , suppressed Rp1‐D21 ‐induced HR. This approach is an efficient way to characterize the roles of genes modulating the hypersensitive defence response and other dominant lesion phenotypes in maize.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

An Integrated View of Hydraulic Induced Fracture Geometry in Hydraulic Fracture Test Site 2

Until relatively recently, most of our understanding about the geometry of hydraulically induced fractures in unconventional reservoirs has been inferred by patterns observed via microseismic monitoring. Important information, such as fracture-azimuth, fracture-length, height-growth and other geometric data has been determined from microseismic “event clouds”, which in turn has been used to interpret a stimulated reservoir volume (SRV). It is important to note that relatively limited microseismic results have been acquired in conjunction with other diagnostics and validated in a consistent manner. The Hydraulic Fracture Test Site 2 (HFTS2) in the Permian Delaware Basin provides a unique opportunity to compare the frac geometry interpretations derived from multiple frac diagnostic tools and at multiple scales. The integrated view that emerges from all the frac diagnostic tools is that in HFTS2 the geometries of hydraulically induced fractures are not random and with a highly complex branching architecture. In fact, the fracs are mostly vertical, parallel plana domains, and both vertically and horizontally asymmetrical. The hydraulically induced fractures have a very consistent azimuth with a strike that matches SHmax. At the distance corresponding to the spacing between nearby wells in HFTS2, ~ 660 ft, the pattern of strain interceptions observed from Low Frequency Distributed Acoustic Sensing (LF-DAS) shows far-field dimensions that are consistent with the stage length dimensions at the stimulated well. In general, larger stages with higher number of clusters create larger number of interceptions and wider stimulated intervals than that of shorter stages with the same cluster to cluster spacing and fewer clusters. The hydraulically induced fractures also show a clear tendency to preferentially grow upwards as shown by the microseismic data, by the relative lower number of LF-DAS interceptions in nearby deeper wells and finally by the observed LF-DAS strain patterns in the vertical observation well. In the near field, the geometries of the fracture domains are also consistent. As shown by the distributed strain measurements obtained during production via the monitoring of Rayleigh Frequency Shift (RFS), each cluster has a separate, non-overlapping, frac-zone-domain that are generally centered around the locations of each perforation cluster. Overall, the hydraulically induced fractures in HFTS2 are interpreted as occurring in swarms associated with individual clusters, each with its own unique geometry but with similar predictable geometric and propagation tendencies. The comprehensive frac diagnostic program in HFTS2, the well-pad layout that permits the investigation of the Downloaded from http://onepetro.org/URTECONF/proceedings-pdf/21URTC/1-21URTC/D011S018R003/2477511/urtec-2021-5396-ms.pdf/1 by Carol Worster on 28 February 2022 URTeC 5396 2 impact that nearby producing wells has on frac geometry, together with an innovative Design of Experiment (DofE) that includes sequential-fracing, consistent cluster-to-cluster distances and few single-perforation cluster stages, has allowed us to gain a unique perspective about the geometry of the induced hydraulic fractures on this pad. Finally, the HFTS2 dataset has also provided us with a better understanding of the applicability and limitations of the different diagnostic tools.

58 GEOSCIENCES↗
DOE OSTI2023

Evaluating the Aftershock Duration of Induced Earthquakes

As the carbon sequestration community prepares to scale up the number and size of commercial operations, the need for tools and methods to assess and mitigate risks associated with these operations becomes increasingly important. One outstanding question is whether aftershocks of induced events decay quickly after injection operations cease or if aftershock activity persists for hundreds of years before returning to background levels more akin to tectonic events (Stein and Liu, 2009). Appropriate estimates of the aftershock duration impact several operational management decisions including mitigation strategies and post-injection monitoring for seismic activity. It is hypothesized that induced earthquake rates may diminish more quickly after injection is stopped, owing to higher stressing rates from injected fluids. Alternatively, it is plausible that only the first event in the sequence is induced by increased fluid overpressures, whereas subsequent events (e.g., aftershocks) respond to the stored tectonic stresses and static and dynamic stress changes due to the mainshock (Keranen et al., 2013). Further, if the aftershock duration can be linked to stressing rates due to injection, then it follows that operational strategies to reduce seismic hazard by reducing injection rates or volumes may be successful. However, if aftershocks of induced events are relieving stored tectonic stresses, then altering injection volumes may not alleviate ongoing seismic activity. Furthermore, knowledge of an aftershock duration could aid in the determination of an appropriate post-injection monitoring period for ongoing seismicity, which is a factor in overall operational costs. In this study, we model induced seismicity sequences in Oklahoma with a coupled Coulomb rate–state earthquake rate model (Dieterich, 1994; Kroll et al., 2017) to estimate aftershocks durations. Results for the current study indicate that elevated rates of aftershock activity following induced mainshocks return to background seismicity rates in less than five years, contrary to the tens to hundreds of years observed for tectonic aftershocks.

58 GEOSCIENCES↗
DOE OSTI2023

Analysis of Fire-Induced Circulations during the FireFlux2 Experiment

Despite recent advances in both coupled fire modeling and measurement techniques to sample the fire environment, the fire–atmosphere coupling mechanisms that lead to fast propagating wildfires remain poorly understood. This knowledge gap adversely affects fire management when wildland fires propagate unexpectedly rapidly and shift direction due to the fire impacts on local wind conditions. In this work, we utilized observational data from the FireFlux2 prescribed burn and numerical simulations performed with a coupled fire–atmosphere model WRF-SFIRE to assess the small-scale impacts of fire on local micrometeorology under moderate wind conditions (10–12 m/s). The FireFlux2 prescribed burn provided a comprehensive observational dataset with in situ meteorological observations as well as IR measurements of fire progression. To directly quantify the effects of fire–atmosphere interactions, two WRF-SFIRE simulations were executed. One simulation was run in a two-way coupled mode in which the heat and moisture fluxes emitted from the fire were injected into the atmosphere, and the other simulation was performed in a one-way coupled mode for which the atmosphere was not affected by the fire. The difference between these two simulations was used to analyze and quantify the fire impacts on the atmospheric circulation at different sections of the fire front. The fire-released heat fluxes resulted in vertical velocities as high as 10.8 m/s at the highest measurement level (20 m above ground level) gradually diminishing with height and dropping to 7.9 m/s at 5.77 m. The fire-induced horizontal winds indicated the strongest fire-induced flow at the lowest measurement levels (as high as 3.3 m/s) gradually decreasing to less than 1 m/s at 20 m above ground level. The analysis of the simulated flow indicates significant differences between the fire-induced circulation at the fire head and on the flanks. The fire-induced circulation was much stronger near the fire head than at the flanks, where the fire did not produce particularly strong cross-fire flow and did not significantly change the lateral fire progression. However, at the head of the fire the fire-induced winds blowing across the front were the strongest and significantly accelerated fire progression. The two-way coupled simulation including the fire-induced winds produced 36.2% faster fire propagation than the one-way coupled run, and more realistically represented the fire progression.

Benik, Jeremy T.↗
DOE OSTI2020

Aristolochic acid-induced genotoxicity and toxicogenomic changes in rodents

Aristolochic acid (AA) is a group of structurally related nitrophenanthrene carboxylic acids found in many plants that are widely used by many cultures as traditional herbal medicines. AA is a causative agent for Chinese herbs nephropathy, a term replaced later by AA nephropathy. Evidence indicates that AA is nephrotoxic, genotoxic, and carcinogenic in humans; and it also induces tumors in the forestomach, kidney, renal pelvis, urinary bladder, and lung of rats and mice. Therefore, plants containing AA have been classified as carcinogenic to humans (Group 1) by the International Agency for Research on Cancer. In our laboratories, we have conducted a series of genotoxicity and toxicogenomic studies in the rats exposed to AA of 0.1–10 mg/kg for 12 weeks. Our results demonstrated that AA treatments induced DNA adducts and mutations in the kidney, liver, and spleen of rats, as well as significant alteration of gene expression in both its target and nontarget tissues. AA treatments altered mutagenesis- or carcinogenesis-related microRNA expression in rat kidney and resulted in significant changes in protein expression profiling. We also applied benchmark dose (BMD) modeling to the 3-month AA-induced genotoxicity data. The obtained BMDL10 (the lower 95% confidence interval of the BMD 10 that is a 10% increase over the background level) for AA-induced mutations in the kidney of rats was about 7 μg/kg body weight per day. This review constitutes an overview of our investigations on AA-induced genotoxicity and toxicogenomic changes including gene expression, microRNA expression, and proteomics; and presents updated information focused on AA-induced genotoxicity in rodents.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

A Project Lifetime Approach to the Management of Induced Seismicity Risk at Geologic Carbon Storage Sites

The geologic storage of carbon dioxide (CO 2 ) is one method that can help reduce atmospheric CO 2 by sequestering it into the subsurface. Large-scale deployment of geologic carbon storage, however, may be accompanied by induced seismicity. We present a project lifetime approach to address the induced seismicity risk at these geologic storage sites. This approach encompasses both technical and nontechnical stakeholder issues related to induced seismicity and spans the time period from the initial consideration phase to postclosure. These recommendations are envisioned to serve as general guidelines, setting expectations for operators, regulators, and the public. They contain a set of seven actionable focus areas, the purpose of which are to deal proactively with induced seismicity issues. Although each geologic carbon storage site will be unique and will require a custom approach, these general best practice recommendations can be used as a starting point to any site-specific plan for how to systematically evaluate, communicate about, and mitigate induced seismicity at a particular reservoir.

58 GEOSCIENCES↗
DOE OSTI2020

Experimental Investigation of Polymer Induced Fouling of Heater Tubes in the First-ever Polymer Flood Pilot on Alaska North Slope

Polymer flooding has been validated in the lab and by successful applications in other countries, such as Canada and China, to be an effective EOR technique for heavy oil reservoirs. Currently, polymer flooding is being pilot tested for the first time in the Schrader Bluff viscous oil reservoir at Milne Point field on Alaska North Slope (ANS). One of the major concerns of the operator is the impact of polymer on the oil production system after polymer breakthrough, especially the polymer induced fouling issues in the heat exchanger. This study investigates the propensity of polymer fouling on the heater tubes as a function of different variables, with the ultimate goal of determining safe and efficient operating conditions. A unique experimental set-up was indigenously designed and developed to simulate the fouling process on the heating tube. The influence of heating tube skin temperature, tube material, and polymer concentration on fouling tendency was investigated. Under each test condition, the test was run five times with the same tube, and in each run, the freshly prepared synthetic brine and polymer solution were heated from 77°F to 122°F to mimic field operating conditions. The heating time and fouling amount were recorded for each run. The morphology and composition of the deposit samples were analyzed by environmental scanning electron microscopy (ESEM) and X-ray diffraction (XRD), respectively. It has been found that, in general, the presence of polymer in produced fluids would aggravate the fouling issues on both carbon steel and stainless steel surfaces at all tested skin temperatures (165°F, 250 °F and 350°F), but only higher skin temperatures of 250°F and 350°F could cause polymer induced fouling issues on the copper tube surface and the fouling tendency increased with polymer concentration. At the lower skin temperatures of 165°F, no polymer-induced fouling was identified on the copper tube. A critical temperature that is related to the cloud point of the polymer solution was believed to exist, below which polymer induced fouling would not occur and only mineral scale deposited, but above which the polymer would obviously aggravate the fouling issue. The heating efficiency of the tube would be reduced gradually as more fouling material accumulates on its surface. The ESEM results indicate that if polymer precipitated and deposited on the surface, it would bond to the mineral crystals to form a stronger three- dimensional network structure, and that is why the polymer induced fouling was tougher and more difficult to be removed from the tube surface. The XRD analysis results confirm that the presence of polymer in the fluids can enhance the mineral scale propensity. Overall, the study results have provided practical guidance to the field operator for the ongoing polymer flooding pilot test on ANS. This study may also prove to be valuable for other chemical EOR projects around the world.

Alaska North Slope↗
DOE OSTI2023

Understanding Ionizing Radiation-Induced Speciation, Chemistry, and Transport in Nuclear Materials

The research to be presented will cover an overview of three projects supported by the United States Department of Energy Office of Science Solar Photochemistry Program: (i) Radiation-Induced Late Actinide Redox Chemistry (2019–2022); (ii) Understanding Radiation-Induced Iodine Speciation, Chemistry, and Transport in High Temperature Molten Salts (2022–2025); and (iii) Radiation-Induced Chemistry of Nuclear Materials (2023–2026). The overarching aim of these distinct projects is to develop a deep fundamental mechanistic understanding of ionizing-radiation-induced processes occurring in solutions over multiple time and length scales. Investigated solutions range from aqueous to organic to molten salt liquids in the presence and absence of ligands and various redox-active ions and molecules, including the actinides. The ultimate goal of these projects is to utilize the new foundational knowledge gained to construct quantitative multiscale computer models with the capacity to predict radiation-induced behavior in complex systems of relevance to nuclear energy technologies and beyond.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2023

Thermal Disorder‐Induced Strain and Carrier Localization Activate Reverse Halide Segregation

The reversal of halide ions is studied under various conditions. However, the underlying mechanism of heat-induced reversal remains unclear. This work finds that dynamic disorder-induced localization of self-trapped polarons and thermal disorder-induced strain (TDIS) can be co-acting drivers of reverse segregation. Localization of polarons results in an order of magnitude decrease in excess carrier density (polaron population), causing a reduced impact of the light-induced strain (LIS – responsible for segregation) on the perovskite framework. Meanwhile, exposing the lattice to TDIS exceeding the LIS can eliminate the photoexcitation-induced strain gradient, as thermal fluctuations of the lattice can mask the LIS strain. Under continuous 0.1 W cm -2 illumination (upon segregation), the strain disorder is estimated to be 0.14%, while at 80 °C under dark conditions, the strain is 0.23%. However, in situ heating of the segregated film to 80 °C under continuous illumination (upon reversal) increases the total strain disorder to 0.25%, where TDIS is likely to have a dominant contribution. Therefore, the contribution of entropy to the system's free energy is likely to dominate, respectively. Various temperature-dependent in situ measurements and simulations further support the results. These findings highlight the importance of strain homogenization for designing stable perovskites under real-world operating conditions.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Ion Implantation-Induced Plastic Phenomena in Metallic Alloys

Ion implantation is widely used for doping semiconductors or electroceramic materials and probing material behaviors in extreme radiation environments. However, implanted ions can induce compressive stresses into the host material, which can induce plasticity and mesoscopic deformation. However, these phenomena have almost exclusively been observed in brittle ionic and/or covalently bonded materials. Here, in this study, we present transmission electron microscopy observations of unusual implantation-induced plasticity in two metallic alloys. First, Fe 2+ ions induce dislocation plasticity below the implanted layer in a model Fe-P alloy. Next, He+ ions form pressurized cavities which activate the fcc-to-hcp strain-induced martensitic transformation in Alloy 625. In both cases, the plasticity can be explained by a combination of implanted ions being incorporated into the lattice and the creation of irradiation defects. These findings have significant implications for mechanical testing of ion-implanted layers, while also opening pathways for using ion implantation to tune stress distributions in metallic alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Microstructure and microchemistry study of irradiation-induced precipitates in proton irradiated ZrNb alloys

Proton irradiation induced Nb redistribution in Zr-xNb alloys (x = 0.4, 0.5, 1.0 wt%) has been investigated using scanning transmission electron microscopy/energy dispersive X-ray spectroscopy (STEM/EDS). Zr-xNb alloys are mainly composed of Zr matrix, native Zr–Nb–Fe phases, and β-Nb precipitates. After 2 MeV proton irradiation at 350 °C, a decrease of Nb content in native precipitates, as well as irradiation-induced precipitation of Nb-rich platelets (135 69 nm long and 27 12 nm wide) were found. Nb-rich platelets and Zr matrix form the Burgers orientation relationship, [$1\bar{1}1$]//[$2\bar{1}\bar{1}0$] and (011)//(0002). The platelets were found to be mostly coherent with the matrix with a few dislocations near the ends of the precipitate. The coherent strain field has been measured in the matrix and platelets by the 4D-STEM technique. Here, the growth of Nb-rich platelets is mainly driven by coherency and dislocation-induced strain fields. Irradiation may both enhance the diffusion and induce segregation of interstitial Nb to the ends of the irradiation induced platelets, further facilitating their growth.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗