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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Thermal Characterization of Acid Treated Anion Exchange Resins

Anion exchange is a chemical separation and purification technique in which a solid phase ion exchanging material (i.e., anion exchange resin beads) interchanges its anions with the desired anions from a solution phase. Typical anion exchange resins (e.g., Bio-Rad AG 1-X8 strongly basic anion exchange resin) consist of a polymer resin bead of cross-linked polystyrene with quaternary ammonium functional groups (Figure 1). Anion exchange occurs at the resin functional groups by exchange of the counter ion of the quaternary ammonium (typically chloride or nitrate) for the anionic species of interest. Other resin polymers have been developed—such as cross-linked vinylpyridine/divinylbenzene utilized in Reillex HPQ anion exchange resin—to improve the resins’ resistance against degradation by oxidizing agents, strong acids, and radiation. Anion exchange is performed for the separation of transuranic (TRU) elements throughout the Department of Energy complex. At the Los Alamos National Laboratory (LANL), production scale quantities of these resins are handled at the Chemistry and Metallurgy Research Facility, the Plutonium Facility, and the Transuranic Waste Facility. Spent anion exchange resin will eventually be disposed of as TRU waste. This has prompted concerns regarding its safe disposal under potential hazard scenarios, in particular a thermal excursion of a TRU waste drum. There is a concern that a potential thermal excursion of a TRU waste drum containing anion exchange resin previously contacted with nitric acid may result in energetic side reactions and pressure buildup due to resin degradation by nitric acid and heat. Therefore, the objective of the experiments described in this report was to gather qualitative and quantitative data to support decisions regarding the thermal stability and safe disposal strategy of nitric acid treated anion exchange resins utilized in TRU processing operations.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2022

60 GHz Outdoor Propagation Measurements and Analysis Using Facebook Terragraph Radios

The high attenuation of millimeter-wave (mmWave) would significantly reduce the coverage areas, and hence it is critical to study the propagation characteristics of mmWave in multiple deployment scenarios. In this work, we investigated the propagation and scattering behavior of 60 GHz mmWave signals in outdoor environments at a travel distance of 98 m for an aerial link (rooftop to rooftop), and 147 m for a ground link (light-pole to light-pole). Measurements were carried out using Facebook Terragraph (TG) radios. Results include received power, path loss, signal-to-noise ratio (SNR), and root mean square (RMS) delay spread for all beamforming directions supported by the antenna array. Strong line-of-sight (LOS) propagation exists in both links. We also observed rich multipath components (MPCs) due to edge scatterings in the aerial link, while only LOS and ground reflection MPCs in the other link.

60 GHz↗
DOE OSTI2021

Role of Surface Termination in the Metal–Insulator Transition of V 2 O 3 (0001) Ultrathin Films

Surface termination is known to play an important role in determining the physical properties of materials. It is crucial to know how surface termination affects the metal–insulator transition (MIT) of V 2 O 3 films for both fundamental understanding and its applications. By changing growth parameters, we achieved a variety of surface terminations in V 2 O 3 films that are characterized by low-energy electron diffraction (LEED) and photoemission spectroscopy techniques. Depending upon the terminations, our results show that MIT can be partially or fully suppressed near the surface region due to the different fillings of the electrons at the surface and subsurface layers and the change of screening length compared to the bulk. Across MIT, a strong redistribution of spectral weight and its transfer from a high-to-low-binding energy regime is observed in a wide energy scale. Our results show that the total spectral weight in the low-energy regime is not conserved across MIT, indicating a breakdown of the “sum rules of spectral weight”, signature of a strongly correlated system. Such a change in spectral weight is possibly linked to the change in hybridization, lattice volume (i.e., effective carrier density), and the spin degree of freedom in the system that occurs across MIT. We find that MIT in this system is strongly correlation-driven, where the electron–electron interactions play a pivotal role. Furthermore, our results provide better insight into the understanding of the electronic structure of strongly correlated systems and highlight the importance of accounting for surface effects during interpretation of the physical property data mainly using surface-sensitive probes, such as surface resistivity.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Linking human-building interactions in shared offices with personality traits

Occupant behavior influences office building energy performance. The level of human-building interactions (HBIs) in shared offices strongly influences building energy use and occupant well-being. This study explored the link between occupant personality types and their behaviors of sharing energy and environment control systems and interactions with their colleagues. Inspired by the Five-Factor Model (FFM), we classified HBI behaviors into four dimensions: willingness to share control, knowledge of control, group decision behavior, and adaptive strategies. These four variables can be mapped to the four personality traits proposed by the FFM: agreeableness, openness, extraversion, and conscientiousness. Our cluster analysis identified six behavioral patterns: average (17.7%), reserved (15.3%), environmentally friendly (16.6%), role model (24.2%), self-centered (17.2%), and mechanist (9.0%). We further applied association rules, a widely utilized machine learning technique, to discover how demographics, building-related contextual factors, and perception-attitudinal factors influence HBI behaviors. Country, control feature accessibility, and group dynamics were found to be the three most influential factors that determine occupants’ HBI behaviors. Finally, the study provides insights about building design and operation, as well as policy to promote socially and environmentally desirable HBI behaviors in a shared office environment.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2026

Methyl formate oxidation kinetics up to 100 atm

Methyl formate (MF, CH3OCHO), the simplest ester, is a representative oxygenated fuel with high oxygen content, and low sooting tendency. However, its oxidation behavior under high-pressure and intermediate-temperature conditions remains insufficiently understood, especially where low-temperature peroxy radical chemistry, methanol chemistry, and pressure-dependent reaction pathways play a critical role. In this study, MF oxidation experiments were conducted in the Princeton supercritical-pressure jet-stirred reactor (SP-JSR) at 20 and 100 atm over the temperature range of 400–950 K under both fuel-lean and fuel-rich conditions. Based on the experimental results, an updated HP-Mech was developed by incorporating previous MF sub-mechanisms, expanded low-temperature peroxy pathways, and evaluated pressure-dependent decomposition kinetics. The newly updated HP-Mech shows greatly improved performance in predicting the onset temperature, the key intermediate species fractions, methanol formation, and the progression of MF oxidation across all the experimental conditions. Path flux analysis indicates that MF consumption at the onset stage is dominated by H-abstraction at the methyl site, forming CH2OCHO radicals that lead to the formation and isomerization of O2CH2OCHO, driving low-temperature chain propagation. Moreover, H-abstraction at the formate site forms CH3OCO radicals that preferentially decompose to CH3, initiating the methanol formation pathway linked to CH3O2 and HO2 chemistry. At the same time, HO2 formation is strongly coupled to MF oxidation through multiple MF-derived radical pathways. HCO originates from MF oxidation and acts as a key coupling species linking fuel consumption to HO2 buildup, especially under high-pressure and intermediate-temperature conditions. In addition to this dominant channel, supplementary HO2 formation pathways involving CH3, CH3O, CH2OH, and CH3O2 reacting with O2 further connect methanol chemistry and oxygenated radical chemistry to the HO2 pool, indicating the central role of HO2 in governing MF oxidation. Sensitivity analysis identifies MF with OH/HO2/CH3O2 reactions and the HO2/H2O2/OH sequence as the key factors controlling reactivity in the high-pressure and intermediate-temperature regime. MF directly reacts with OH/HO2/CH3O2 to consume the fuel and produce reactive radicals like CH2OCHO and CH3OCO that undergo subsequent oxidation pathways. Moreover, HO2 recombination suppresses oxidation at lower temperatures, while thermal decomposition of H2O2 accelerates OH production and promotes fuel consumption as temperature increases. The direct formation of active OH from HO2 radicals further completes the mechanism, improving its prediction especially during the oxidation onset stage.

Low-temperature Chemistry↗
DOE OSTI2021

Amino‐Functionalised Hybrid Ultramicroporous Materials that Enable Single‐Step Ethylene Purification from a Ternary Mixture

Abstract Pyrazine‐linked hybrid ultramicroporous (pore size <7 Å) materials (HUMs) offer benchmark performance for trace carbon capture thanks to strong selectivity for CO 2 over small gas molecules, including light hydrocarbons. That the prototypal pyrazine‐linked HUMs are amenable to crystal engineering has enabled second generation HUMs to supersede the performance of the parent HUM, SIFSIX‐3‐Zn , mainly through substitution of the metal and/or the inorganic pillar. Herein, we report that two isostructural aminopyrazine‐linked HUMs, MFSIX‐17‐Ni (17=aminopyrazine; M=Si, Ti), which we had anticipated would offer even stronger affinity for CO 2 than their pyrazine analogs, unexpectedly exhibit reduced CO 2 affinity but enhanced C 2 H 2 affinity. MFSIX‐17‐Ni are consequently the first physisorbents that enable single‐step production of polymer‐grade ethylene (>99.95 % for SIFSIX‐17‐Ni ) from a ternary equimolar mixture of ethylene, acetylene and CO 2 thanks to coadsorption of the latter two gases. We attribute this performance to the very different binding sites in MFSIX‐17‐Ni versus SIFSIX‐3‐Zn .

Mukherjee, Soumya↗
DOE OSTI2021

Amino‐Functionalised Hybrid Ultramicroporous Materials that Enable Single‐Step Ethylene Purification from a Ternary Mixture

Abstract Pyrazine‐linked hybrid ultramicroporous (pore size <7 Å) materials (HUMs) offer benchmark performance for trace carbon capture thanks to strong selectivity for CO 2 over small gas molecules, including light hydrocarbons. That the prototypal pyrazine‐linked HUMs are amenable to crystal engineering has enabled second generation HUMs to supersede the performance of the parent HUM, SIFSIX‐3‐Zn , mainly through substitution of the metal and/or the inorganic pillar. Herein, we report that two isostructural aminopyrazine‐linked HUMs, MFSIX‐17‐Ni (17=aminopyrazine; M=Si, Ti), which we had anticipated would offer even stronger affinity for CO 2 than their pyrazine analogs, unexpectedly exhibit reduced CO 2 affinity but enhanced C 2 H 2 affinity. MFSIX‐17‐Ni are consequently the first physisorbents that enable single‐step production of polymer‐grade ethylene (>99.95 % for SIFSIX‐17‐Ni ) from a ternary equimolar mixture of ethylene, acetylene and CO 2 thanks to coadsorption of the latter two gases. We attribute this performance to the very different binding sites in MFSIX‐17‐Ni versus SIFSIX‐3‐Zn .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Experimental study on the role of the target electron temperature as a key parameter linking recycling to plasma performance in JET-ILW*

Changes in global and edge plasma parameters (H98(y,2), dimensionless collisionality ν*, core density peaking, separatrix density ne,sep) with variations in the D2 fueling rate and divertor configuration are unified into a single trend when mapped to $\langle$Te,ot$\rangle$, the spatially averaged spectroscopically derived outer target electron temperature. Dedicated JET with the ITER-like wall (JET-ILW) experiments in combination with an extended JET-ILW database of unseeded low-triangularity H-mode plasmas spanning a wide range of D2 fueling rates, Ip, Bt and heating power have demonstrated the importance of $\langle$Te,ot$\rangle$ as a key physics parameter linking the recycling particle source and detachment with plasma performance. The remarkably robust H98(y,2) trend with $\langle$Te,ot$\rangle$ is connected to a strong inverse correlation between $\langle$Te,ot$\rangle$, ne,sep and ν*, thus directly linking changes in the divertor recycling moderated by $\langle$Te,ot$\rangle$ with the previously established relationship between ν*, core density peaking and core pressure resulting in a degradation in core plasma performance with decreasing $\langle$Te,ot$\rangle$ (increasing ν*). Additionally, a strong inverse correlation between the separatrix to pedestal density ratio, ne,sep/ne,ped, and $\langle$Te,ot$\rangle$ is also established, with the rise in ne,sep/ne,ped saturating at $\langle$Te,ot$\rangle$ > 10 eV. A strong reduction in H98(y,2) is observed as $\langle$Te,ot$\rangle$ is driven from 30 to 10 eV via additional D2 gas fueling, while the divertor remains attached. Consequently, the pronounced performance degradation in attached divertor conditions has implications for impurity seeding radiative divertor scenarios, in which H98(y,2) is already low (~0.7) before impurities are injected into the plasma since moderate gas fueling rates are required to promote high divertor neutral pressure. A favorable pedestal pressure, pe,ped, dependence on Ip has also been observed, with an overall increase in pe,ped at Ip = 3.4 MA as $\langle$Te,ot$\rangle$ is driven down from attached to high-recycling divertor conditions. In contrast, pe,ped is reduced with decreasing $\langle$Te,ot$\rangle$ in the lower Ip branches. Further work is needed to (i) clarify the potential role of edge opacity on the observed favorable pedestal pressure Ip scaling; as well as to (ii) project the global and edge plasma performance trends with $\langle$Te,ot$\rangle$ to reactor-scale devices to improve predictive capability of the coupling between recycling and confined plasma fueling in what are foreseen to be more opaque edge plasma conditions.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Facilely Cross-Linking Polybenzimidazole with Polycarboxylic Acids to Improve H 2 /CO 2 Separation Performance

Polybenzimidazole (PBI) with a strong size-sieving ability exhibits attractive H 2 /CO 2 separation properties for blue H 2 production and CO 2 capture. Herein, we report that PBI can be facilely cross-linked with polycarboxylic acids, oxalic acid (OA), and trans-aconitic acid (TaA) to improve its separation performance. The acids react with the amines on the PBI chains, decreasing free volume and increasing size-sieving ability. The acid doping increases H 2 /CO 2 selectivity from 12 to as high as 45 at 35 °C. Here, the acid-doped samples demonstrate stable H 2 /CO 2 separation performance when challenged with simulated syngas containing water vapor at 150 °C, which surpasses state-of-the-art polymers and Robeson’s upper bound for H 2 /CO 2 separation.

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

Structural Insight into a Sixteen Cyanine Dye Construct via Exciton–Exciton Annihilation

Molecular (dye) aggregates play a prominent role in light harvesting and are of interest in quantum information science; however, there are limited reports hat programmably assemble many (>4) dye aggregates featuring strong coupling and exciton delocalization. Using oligonucleotides with four Cy5s covalently linked in series along the phosphate backbone, we bring four, eight, and sixteen Cy5s in close proximity by assembling four-armed junctions. We elucidate their structure via gel electrophoresis and steady-state and transient optical spectroscopy. We find that Cy5 has a strong propensity to form tetramer clusters, where the exciton is delocalized over all four Cy5s, that the exciton is not delocalized beyond tetramer clusters in the eight and sixteen Cy5 constructs, and that the sixteen Cy5 construct may consist of pairs of tetramer clusters that are isolated from one another. Many-dye aggregates such as these may serve useful as antennae for their intense light absorption and spatially directed energy transfer.

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

Crystalline Order Yet Glass-Like Heat Transport Driven by Hidden Local Distortions as the Structural Origin of Ultralow Thermal Conductivity in AgErTe 2

Given their rich chemical diversity and the interplay among the p-, d-, and f-orbitals of chalcogens, transition metals, and lanthanides, respectively, rare-earth transition-metal chalcogenides exhibit a wide variety of structural, magnetic, and transport phenomena. As a result, they form a particularly appealing platform for investigating structure–property relationships, emergent electronic and magnetic behaviors, and thermal transport. Here we investigate AgErTe 2 as a model system to understand phonon-glass behavior in ordered crystalline solids, which establishes the design principles for thermal barrier coatings and next-generation thermoelectrics. The local bonding asymmetry and lattice softness suppress the inherently low lattice thermal conductivity, resembling the characteristics of amorphous materials. This suppression is significantly influenced by local off-centering of Ag atoms, which breaks lattice periodicity while maintaining global crystallinity. The presence of antibonding states just below the Fermi level, arising from Ag 4d and Te 5p orbital interactions, leads to lattice softening and destabilizes ideal tetrahedral coordination, resulting in a pseudo Jahn–Teller distortion. Furthermore, the coexistence of weaker, more polarizable Ag–Te bonds and stronger Er–Te bonds creates a complex vibrational landscape enriched with low-frequency modes and enhanced phonon scattering. A pronounced disparity in interatomic force constants gives rise to highly localized, low-energy optical phonons linked to Ag rattling. These flat vibrational modes exhibit strong coupling with transverse acoustic phonons, resulting in ultrashort phonon lifetimes and mean free paths approaching interatomic distances. These features collectively enhance phonon scattering across a broad range of length and energy scales. This work offers a framework for engineering suppressed thermal conductivity in crystalline systems without the introduction of alloying elements.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

The public health exposome and pregnancy-related mortality in the United States: a high-dimensional computational analysis

Racial inequities in maternal mortality in the U.S. continue to be stark. The 2015–2018, 4-year total population, county-level, pregnancy-related mortality ratio (PRM; deaths per 100,000 live births; National Center for Health Statistics (NCHS), restricted use mortality file) was linked with the Public Health Exposome (PHE). Using data reduction techniques, 1591 variables were extracted from over 62,000 variables for use in this analysis, providing information on the relationships between PRM and the social, health and health care, natural, and built environments. Graph theoretical algorithms and Bayesian analysis were applied to PHE/PRM linked data to identify latent networks. PHE variables most strongly correlated with total population PRM were years of potential life lost and overall life expectancy. Population-level indicators of PRM were overall poverty, smoking, lack of exercise, heat, and lack of adequate access to food. In this high-dimensional analysis, overall life expectancy, poverty indicators, and health behaviors were found to be the strongest predictors of pregnancy-related mortality. This provides strong evidence that maternal death is part of a broader constellation of both similar and unique health behaviors, social determinants and environmental exposures as other causes of death.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2026

Interactions between molecular-scale biogeochemical processes and hyporheic exchange for understanding coupled Fe-S-C cycling in iron-rich riparian wetlands (Final Technical Report)

Riparian wetlands are dynamic interfaces that exert strong control over water quality, contaminant mobility, and greenhouse gas emissions. These systems are characterized by hyporheic exchange between oxic surface water and anoxic groundwater, which generates steep redox gradients and promotes spatially and temporally variable microbial activity. Despite growing recognition of tightly coupled iron (Fe), sulfur (S), and carbon (C) cycling in these environments, the mechanisms governing these interactions—particularly under low-sulfate freshwater conditions—remain poorly constrained. This project developed a mechanistic understanding of how hydrologic variability and microbial processes interact to control Fe–S–C cycling in iron-rich riparian wetlands. Using a multi-scale and multi-method approach integrating field observations, geochemical and spectroscopic analyses, metagenomics, and reactive transport modeling, we demonstrate that “cryptic” sulfur cycling—rapid sulfur transformations involving intermediate-valence species—plays a dominant and previously underrecognized role in freshwater wetlands. These processes persist despite low sulfate concentrations and significantly influence iron reduction, carbon mineralization, and methane dynamics. The results show that cryptic sulfur cycling enhances dissolved Fe 2+ production, regulates methane concentrations, and is strongly controlled by climate-driven hydrologic fluxes. By linking hydroclimate, subsurface flow, and biogeochemical reactions, this work provides a predictive framework for understanding how wetland systems respond to environmental change, with direct implications for water quality and carbon cycling.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2021

Photon pumping in a weakly-driven quantum cavity–spin system

Highlights: • We study photon frequency conversion in a driven spin coupled to a cavity mode. • Quantized frequency conversion is excpected in the strong-drive adiabatic limit. • A new photon pumping effect is established in the accessible weak drive regime. • Pumping is linked to the delocalization of the corresponding Floquet states. • Quantum coherence is preserved in both the strong and ultraweak-drive limits. We investigate the photon pumping effect in a topological model consisting of a periodically driven spin-1/2 coupled to a quantum cavity mode out of the adiabatic limit. In the strong-drive adiabatic limit, a quantized frequency conversion of photons is expected as the temporal analog of the Hall current. We numerically establish a novel photon pumping phenomenon in the experimentally accessible nonadiabatic driving regime for a broad region of the parameter space. The photon frequency conversion efficiency exhibits strong fluctuations and high efficiency that can reach up 80% of the quantized value for commensurate frequency combinations. We link the pumping properties to the delocalization of the corresponding Floquet states which display multifractal behavior as the result of hybridization between localized and delocalized sectors. Finally we demonstrate that the quantum coherence properties of the initial state are preserved during the frequency conversion process in both the strong and ultra-weak-drive limit.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

Development of Automated Pipeline for Time-Resolved Link-Wise Vehicular Energy Consumption in the Chattanooga, TN Road Network

The Department of Energy (DOE) has shown strong interest in detecting energy inefficiencies in regional road networks, so as to derive energy consumed at a high spatial temporal resolution. We have developed a workflow to automate the estimation of time-resolved vehicular energy consumption over each link in a road network of interest. The road network used in the current work is centered around the city of Chattanooga, Tennessee and its bordering regions. Utilizing the most mature road network for the Chattanooga, TN region, vehicle speed & count data from TomTom in conjunction with machine learning methods, we have developed an automated pipeline to estimate energy consumption for every link in the network. The first step in the pipeline is ingesting vehicle probe counts and speed estimates from TomTom API. In the next step, the probe counts, speed profiles and other exogenous data (i.e. road types, weather data, ground-truth volume counts and more) were used as input to a supervised learning algorithm to estimate the number of vehicles throughout the entire region for each road segment. These volume estimates were then mapped to a unified road network that contained additional important information such as percentage change in gradient across a link, number of lanes and link lengths that are features in pre-trained single vehicle energy-consumption models available with the RouteE software developed at NREL. The per vehicle energy consumption on each road link predicted using appropriate RouteE vehicular models were multiplied by the volume estimate for the corresponding link over a given time period to predict energy consumed per link for the time interval of interest. Currently, work is underway to improve both the RouteE per vehicle energy estimate and the volume estimates derived from TomTom probe counts. We have also explored the correlation of the link-wise energy estimates with the features of the pre-trained RouteE machine learning model in order to gain insight into what factors contribute most to the link-wise energy consumption.

ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION,↗
DOE OSTI2026

Dynamic crushing of metal lattice metamaterials: Shock mode diagrams and transition to topology-independent compaction regime

Additively manufactured lattice metamaterials offer design versatility in strength and energy absorption and provide an additional degree of freedom through the selection of the lattice topology. Under quasistatic loading, the unit cell structure can strongly affect the stiffness, yield, and post-yield behavior, but whether and to what degree the effect of lattice topology persists into dynamic loading scenarios, up to the compaction shock regime, has not been established. LLNL’ s ALE3D hydrocode was used to perform a computational investigation of dynamic loading in multiple lattice types, including the gyroid, octet, Schwarz D, and rhombic dodecahedron, under impact velocities from 0.25 to 2.25 km/s. Shock Hugoniots for each lattice topology are generated and compared, suggesting that above a critical velocity, distinctions between architectures may not persevere and compacted lattices behave similarly. Here, to investigate the transition between topology-dependent quasistatic compression and the topology-independent regime above the critical velocity, a one-dimensional elastic-linear hardening plasticity-densified solid (E-LHP-DS) shock model for lattice materials was developed that relies upon confined compression to link the quasistatic and shock mechanics. Unlike similar works, the model does not assume rigid behavior prior to yield or locking behavior at densification, allowing a richer exploration of lattice mechanics. With only six parameters, the analytical model simultaneously fit quasistatic confined compression simulations for relative densities 0.1 $≤ \bar{ρ} ≤$ 0.9 and predicted dynamic compaction behavior to traverse several distinct shock modes, each defined by a critical impact speed (equivalently, critical stresses). Comparing the numerical results to the one-dimensional E-LHP-DS shock model predictions suggests that the topology-independence under strong shocks is linked to the onset of densification, which can be predicted based on quasistatic confined compression results.

Cellular material↗
DOE OSTI2022

Golgi-localized putative S-adenosyl methionine transporters required for plant cell wall polysaccharide methylation

Polysaccharide methylation, especially that of pectin, is a common and important feature of land plant cell walls. Polysaccharide methylation takes place in the Golgi apparatus and therefore relies on the import of S-adenosyl methionine (SAM) from the cytosol into the Golgi. However, so far, no Golgi SAM transporter has been identified in plants. Here we studied major facilitator superfamily members in Arabidopsis that we identified as putative Golgi SAM transporters (GoSAMTs). Knockout of the two most highly expressed GoSAMTs led to a strong reduction in Golgi-synthesized polysaccharide methylation. Furthermore, solid-state NMR experiments revealed that reduced methylation changed cell wall polysaccharide conformations, interactions and mobilities. Notably, NMR revealed the existence of pectin ‘egg-box’ structures in intact cell walls and showed that their formation is enhanced by reduced methyl esterification. Here, these changes in wall architecture were linked to substantial growth and developmental phenotypes. In particular, anisotropic growth was strongly impaired in the double mutant. The identification of putative transporters involved in import of SAM into the Golgi lumen in plants provides new insights into the paramount importance of polysaccharide methylation for plant cell wall structure and function.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Achieving Multimodal and Multicolor Luminescence in LaAlO 3 :Pr 3+ , Gd 3+ via Trap Engineering and Energy Transfer

Achieving multimodal luminescence within a single phosphor is vital for multifunctional applications but remains challenging due to complex color tuning and trap engineering. In this study, we report Pr 3+ and Gd 3+ co‐doped LaAlO 3 (LAO:PG) phosphors, designed through careful modulation of multilevel traps and Pr 3+ → Gd 3+ energy transfer dynamics. These materials exhibit diverse luminescence modes, including down‐conversion luminescence (DCL), up‐conversion luminescence (UCL), persistent luminescence (PersL), optically stimulated luminescence (OSL), and thermally stimulated luminescence (TSL) across a wide spectral range. Unlike previously studied Pr 3+ ‐doped LAO, the co‐doped LAO:PG shows DCL in both UV‐visible and NIR regions and displays ultraviolet‐C UCL under visible excitation. Notably, we observe, for the first time, PersL lasting several minutes in these phosphors—an improvement over the non‐PersL behavior of Pr 3+ ‐only doped LAO. Additionally, the LAO:PG phosphors exhibit strong OSL response. TSL analysis reveals five distinct trap levels linked to these properties. Density functional theory calculations further correlate intrinsic defects to these traps, supporting a proposed mechanism for the observed multimodal luminescence. These findings highlight LAO:PG as a promising platform for developing advanced phosphors with integrated luminescence modes, paving the way for future applications in data storage, phototherapy, and anti‐counterfeiting technologies.

Chemistry↗