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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 OSTI2022

Measurement of Resistance, Porosity, and Water Contact Angle of Porous Transport Layers for Low-Temperature Electrolysis Technologies

The porous transport layer is an important component of low-temperature electrolysis devices, such as proton exchange membrane water electrolyzers or anion exchange membrane water electrolyzers. PTLs have significant influence on the cell performance as their bulk resistance can impact the ohmic resistance, their contact resistance can impact electrode performance, and their structure can impact the liquid flow to the cell, which could cause mass-transport losses. In order to improve cell performance, optimization of the PTL is critical. Standardized protocols should be utilized to adequately compare PTLs being developed from different institutions. This method will detail a standardized protocol for measuring the resistance of the PTL using a four-wire setup and will also detail a process for measuring the porosity and water contact angle of the PTL using capillary flow porometry.

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

Structural complexity and primary production resistance are coupled in a temperate forest

The capacity of forests to resist structural change and retain material legacies–the biotic and abiotic resources that persist through disturbance–is crucial to sustaining ecosystem function after disturbance. However, the role of forest structure as both a material legacy and feature supporting carbon (C) cycling stability following disturbance has not been widely investigated. We used a large-scale disturbance manipulation to ask whether legacies of lidar-derived canopy structures drive 3-year primary production responses to disturbance. As part of the Forest Resilience Threshold Experiment (FoRTE) in northern Michigan, USA we simulated phloem-disrupting disturbances producing a range of severities and affecting canopy trees of different sizes. We quantified the legacies of forest structure using two approaches: one measuring the change in structure and primary production from pre-to post-disturbance and the second estimating resistance as log transformed ratios of control and treatment values. We found that total aboveground wood net primary production (ANPP w ) was similar across disturbance severities as legacy trees rapidly increased rates of primary production. Experiment-wide, the disturbance had limited effects on change in mean structural complexity values; however, high variance underscored large differences in the magnitude and direction of complexity's response at the plot-scale. Plot-scale structural complexity, but not vegetation area index (VAI), resistance strongly predicted ANPP w resistance while temporal VAI and structural complexity changes did not. We conclude that the presence of material legacies in the form of forest structure may affect primary production stability following disturbance and that how legacies are quantified may affect the interpretation of disturbance response.

lidar—remote sensing↗
DOE OSTI2022

Effect of Endosymbiotic Bacteria on Fungal Resistance Toward Heavy Metals

Most studies on metal removal or tolerance by fungi or bacteria focus on single isolates, without taking into consideration that some fungi in nature may be colonized by endobacteria. To address this knowledge gap, we investigated the tolerance and removal of diverse metals with two fungal species: Linnemannia elongata containing Burkholderia-related endobacteria and Benniella erionia containing Mollicute-related endobacteria. Isogenic lines of both species were generated with antibiotic treatments to remove their respective endobacteria. Experiments involved comparing the isogenic lines and wild type fungi in relation to the minimum inhibitory concentration for the metals, the fungal ability to remove these different metals via atomic adsorption spectroscopy, and the interaction of the metals with specific functional groups of the fungi and fungi-bacteria to determine the role of the bacteria via attenuated total reflection fourier transformed infrared (ATR-FTIR). Finally, we determined the influence of different metal concentrations, associated with moderate and high fungal growth inhibition, on the presence of the endobacteria inside the fungal mycelium via quantitative real-time PCR. Results showed that the presence of the endosymbiont increased B. erionia resistance to Mn 2+ and increased the removal of Fe 2+ compared to isogenic lines. The absence of the endosymbiont in L. elongata increased the fungal resistance toward Fe 2+ and improved the removal of Fe 2+ . Furthermore, when the bacterial endosymbiont was present in L. elongata , a decrease in the fungal resistance to Ca 2+ , Fe 2+ , and Cr 6+ was noticeable. In the ATR-FTIR analysis, we determined that C-H and C = O were the major functional groups affected by the presence of Cu 2+ , Mn 2+ , and Fe 2+ for L. elongata and in the presence of Cu 2+ and Ca 2+ for B. eronia . It is noteworthy that the highest concentration of Pb 2+ led to the loss of endobacteria in both L. elongata and B. eronia , while the other metals generally increased the concentration of endosymbionts inside the fungal mycelium. From these results, we concluded that bacterial endosymbionts of fungi can play a fundamental role in fungal resistance to metals. This study provides the first step toward a greater understanding of symbiotic interactions between bacteria and fungi in relation to metal tolerance and remediation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Engineering Atomic-to-Nano Scale Structural Homogeneity towards High Corrosion Resistance of Amorphous Magnesium-Based Alloys

Magnesium-based amorphous alloys have aroused broad interest in being applied in marine use due to their merits of lightweight and high strength. Yet, the poor corrosion resistance to chloride-containing seawater has hindered their practical applications. Herein, we propose a new strategy to improve the chloride corrosion resistance of amorphous Mg 65 Cu 15 Ag 10 Gd 10 alloys by engineering atomic-to-nano scale structural homogeneity, which is implemented by heating the material to the critical temperature of the liquid–liquid transition. By using various electrochemical, microscopic, and spectroscopic characterization methods, we reveal that the liquid–liquid transition can rearrange the local structural units in the amorphous structure, slightly decreasing the alloy structure’s homogeneity, accelerate the formation of protective passivation film, and, therefore, increase the corrosion resistance. Our study has demonstrated the strong coupling between an amorphous structure and corrosion behavior, which is available for optimizing corrosion-resistant alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Predicting Drug Resistance Using Deep Mutational Scanning

Drug resistance is a major healthcare challenge, resulting in a continuous need to develop new inhibitors. The development of these inhibitors requires an understanding of the mechanisms of resistance for a critical mass of occurrences. Recent genome editing technologies based on high-throughput DNA synthesis and sequencing may help to predict mutations resulting in resistance by testing large mutagenesis libraries. Here we describe the rationale of this approach, with examples and relevance to drug development and resistance in malaria.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Synergistic Integration of Chemo-Resistive and SERS Sensing for Label-Free Multiplex Gas Detection

Practical sensing applications such as real-time safety alerts and clinical diagnoses require sensor devices to differentiate between various target molecules with high sensitivity and selectivity, yet conventional devices such as oxide-based chemo-resistive sensors and metal-based surface-enhanced Raman spectroscopy (SERS) sensors usually do not satisfy such requirements. In this report a label-free, chemo-resistive/SERS multimodal sensor based on a systematically assembled 3D cross-point multifunctional nanoarchitecture (3D-CMA), which has unusually strong enhancements in both “chemo-resistive” and “SERS” sensing characteristics is introduced. 3D-CMA combines several sensing mechanisms and sensing elements via 3D integration of semiconducting SnO 2 nanowire frameworks and dual-functioning Au metallic nanoparticles. It is shown that the multimodal sensor can successfully estimate mixed-gas compositions selectively and quantitatively at the sub-100 ppm level, even for mixtures of gaseous aromatic compounds (nitrobenzene and toluene) with very similar molecular structures. This is enabled by combined chemo-resistive and SERS multimodal sensing providing complementary information.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Integrated High‐Throughput and Machine Learning Methods to Accelerate Discovery of Molten Salt Corrosion‐Resistant Alloys

Insufficient availability of molten salt corrosion-resistant alloys severely limits the fruition of a variety of promising molten salt technologies that could otherwise have significant societal impacts. To accelerate alloy development for molten salt applications and develop fundamental understanding of corrosion in these environments, here an integrated approach is presented using a set of high-throughput (HTP) alloy synthesis, corrosion testing, and modeling coupled with automated characterization and machine learning. By using this approach, a broad range of Cr-Fe-Mn-Ni alloys are evaluated for their corrosion resistances in molten salt simultaneously demonstrating that corrosion-resistant alloy development can be accelerated by 2 to 3 orders of magnitude. Based on the obtained results, a sacrificial protection mechanism is unveiled in the corrosion of Cr-Fe-Mn-Ni alloys in molten salts which can be applied to protect the less unstable elements in the alloy from being depleted, and provided new insights on the design of high-temperature molten salt corrosion-resistant alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Exploring novel HIV ‐1 reverse transcriptase inhibitors with drug‐resistant mutants: A double mutant surprise

Abstract HIV‐1 reverse transcriptase (RT) remains a key target for HIV drug development. As successful management of the disease requires lifelong treatment, the emergence of resistance mutations is inevitable, making development of new RT inhibitors, which remain effective against resistant variants crucial. To this end, previous computationally guided drug design efforts have resulted in catechol diether compounds, which inhibit wildtype RT with picomolar affinities and appear to be promising preclinical candidates. To confirm that these compounds remain potent against Y181C, a widespread mutation conferring resistance to first generation inhibitors, they were screened against the HIV‐1 N119 clinical isolate, reported as a Y181C single mutant. In comparison to a molecular clone with the same mutation, N119 appears less susceptible to inhibition by our preclinical candidate compounds. A more detailed sequencing effort determined that N119 was misidentified and carries V106A in combination with Y181C. While both indolizine and naphthalene substituted catechol diethers are potent against the classical Y181C single mutant, the addition of V106A confers more resistance against the indolizine derivatives than the naphthalene derivatives. Crystal structures presented in this study highlight key features of the naphthyl group, which allow these compounds to remain potent in the double mutant, including stronger interactions with F227 and less reliance on V106 for stabilization of the ethoxy‐uracil ring, which makes critical hydrogen bonds with other residues in the binding pocket.

Biochemistry & Molecular Biology↗
DOE OSTI2025

Soybean rust‐resistant and tolerant varieties identified through the Pan‐African Trial Network

Abstract BACKGROUND The global demand for soybeans is increasing rapidly, with projections indicating an escalation of 70–80 million metric tons over the next decade. Sub‐Saharan Africa (SSA) contributes significantly to this growth, with soybean production increasing by 6.8% per year, outpacing the global average increase of 4.7%. Despite the expansion, soybean productivity in Africa remains less than half of the global average. This yield gap is largely due to diseases and pests, such as soybean rust, which can be particularly severe. Effective management of soybean rust depends on several factors, including resistant cultivars. However, there has been limited information on the rust‐resistance levels of African cultivars. To address this gap, the Pan‐African Trial network conducted soybean varietal trials across diverse locations. RESULT Analyzing data from 370 individual trials conducted between 2015–2022, the network identified 81 cultivars with sufficient rust‐resistance data. Six cultivars including, Black Hawk, Dundee, Egret, Heron, Ibis, and Peka 06 were found to be resistant, and 12 were classified as tolerant. CONCLUSION This research is a significant step forward in improving soybean productivity in Africa, and further assessments are being undertaken to address other crop production challenges in the region. © 2025 Society of Chemical Industry.

Favoretto, Vitor Rampazzo [Cenex Harvest States (C↗
DOE OSTI2024

Genome‐wide association studies on resistance to powdery mildew in cultivated emmer wheat

Abstract Powdery mildew, caused by the fungal pathogenBlumeria graminis(DC.) E. O. Speer f. sp.triticiEm. Marchal (Bgt), is a constant threat to global wheat (Triticum aestivumL.) production. Although ∼100 powdery mildew (Pm) resistance genes and alleles have been identified in wheat and its relatives, more is needed to minimizeBgt’s fast evolving virulence. In tetraploid wheat (Triticum turgidumL.), wild emmer wheat [T. turgidumssp.dicoccoides(Körn. ex Asch. & Graebn.) Thell.] accessions from Israel have contributed manyPmresistance genes. However, the diverse genetic reservoirs of cultivated emmer wheat [T. turgidumssp.dicoccum(Schrank ex Schübl.) Thell.] have not been fully exploited. In the present study, we evaluated a diverse panel of 174 cultivated emmer accessions for their reaction toBgtisolateOKS(14)‐B‐3‐1and found that 66% of accessions, particularly those of Ethiopian (30.5%) and Indian (6.3%) origins, exhibited high resistance. To determine the genetic basis ofBgtresistance in the panel, genome‐wide association studies were performed using 46,383 single nucleotide polymorphisms (SNPs) from genotype‐by‐sequencing and 4331 SNPs from the 9K SNP Infinium array. Twenty‐five significant SNP markers were identified to be associated withBgtresistance, of which 21 SNPs are likely novel loci, whereas four possibly represent emmer derivedPm4a,Pm5a,PmG16, andPm64. Most novel loci exhibited minor effects, whereas three novel loci on chromosome arms 2AS, 3BS, and 5AL had major effect on the phenotypic variance. This study demonstrates cultivated emmer as a rich source of powdery mildew resistance, and the resistant accessions and novel loci found herein can be utilized in wheat breeding programs to enhanceBgtresistance in wheat.

Genetics & Heredity↗
DOE OSTI2020

The production of hydrogen–deuterium exchanged cellulose fibers with exchange-resistant deuterium incorporation

Production of deuterated cellulose is important from both theoretical and practical perspectives. Here, cellulose fibers of cotton and Tencel fibers with exchange-resistant deuterium incorporation were prepared by hydrogen–deuterium exchange treatment. The effect of the micro-structure of cellulose crystallinity index as well as the reaction conditions including catalyst, reaction time, and temperature on the exchange-resistant deuterium incorporation process are reported. The ability of deuterated cellulose fibers to resist protium-exchange during H 2 O washing was also explored. The results found that higher crystallinity index is beneficial to stabilize the deuteration of cellulose fibers. Furthermore, alkaline catalysts such as sodium hydroxide or potassium carbonate and higher exchange temperature as well as longer reaction time contribute significantly to the stabilization of deuterium incorporation in the deuterated cellulose fibers. These observations revealed that the hydrogen–deuterium exchange treatment is effective to obtain exchange-resistant deuterium incorporated cellulose fibers. In addition, cotton fibers with several deuteration levels were produced and could be considered for the study of deuterium effect on cellulose properties.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Evidence of Superconductivity in Electrical Resistance Measurements of Hydrides Under High Pressure

In the standard van der Pauw four-probe configuration commonly used for electrical resistance measurements, including those of hydrogen-rich samples at high pressures, the application of electrical current through one pair of leads while measuring voltage difference across another pair is a fundamental practice (see the inset in Fig. 1c). In the scenario described in Ref. [5], where electrical resistance vanishes due to disconnection between current and voltage probes or due to an onset of giant magnetoresistance in parts of the sample, it is crucial to consider the implications across different probe orientations: while one orientation may indeed result in vanishing electrical resistance, a divergence of the electrical resistance towards infinity will be observed in an alternative orientation where the applied current pattern is rotated a quarter turn (see the scheme on the inset in Fig. 1c). It is imperative to acknowledge that experimental data encompassing all possible probe orientations are essential for eliminating artifacts and assessing sample homogeneity.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2022

Cavitation-resistant intergranular precipitates enhance creep performance of θ'-strengthened Al-Cu based alloys

Tensile and compressive creep properties of a quaternary Al-Cu-Mn-Zr (ACMZ) alloy and its commercial counterpart (Al-Cu-Mn-Zr with Ni, Co and Sb additions, RR350) are investigated at 300°C. At low stresses up to 30 MPa where diffusional creep dominates, creep resistance is the same in tension and compression and RR350 deforms more slowly than ACMZ, consistent with RR350 alloy's larger linear fraction of intergranular precipitates (Al7Cu2(NiFe) and Al9FeNi for RR350 vs. θ-Al2Cu for ACMZ) and a reduced fraction of precipitate-free zones near grain boundaries. At stresses between 30 and 80 MPa, dislocation creep with a stress exponent n ~ 3 becomes rate-limiting in compression, which is expected to be controlled by θ' precipitates within the grain bulk. By contrast, in tension, enhanced creep rate and higher apparent stress exponents are measured, consistent with cavitation at intergranular precipitates becoming increasingly dominant as the stress increases. In the dislocation creep regime, RR350 alloy is again more creep resistant than ACMZ alloy, which is related to three mechanisms (i) a reduced fraction of softer precipitate-free zones, (ii) more effective load transfer to intergranular precipitates, and (iii) reduced cavitation. A model for cavitation is applied to calculate tensile creep rates from compressive creep rates and the model successfully predicts the improved tensile creep resistance of the RR350 alloy. Overall, the present investigation underscores the importance of intergranular grain boundary precipitates, in addition to strengthening θ' precipitates, in enhancing the creep resistance of Al-Cu alloys.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Ultra-low thermal resistance and pressure drop copper and copper-tungsten diamond-shaped pin fin cold plates for liquid cooling of electronics

Modern and future data centers face increasing cooling challenges due to increasing chip thermal design power and die size, along with the need to reduce energy consumption used for cooling. High performance cooling solutions that maintain a low chip junction temperature are needed to ensure electronics reliability. This work develops an ultra-low thermal resistance and low pressure drop 75 mm × 75 mm cold plate, intended for next-generation electronics cooling. The cold plate features an array of diamond-shaped pin fins and integrated copper tungsten heat spreader, selected for its low coefficient of thermal expansion which reduces thermomechanical deformation and allows for closer integration of the cold plate with silicon dies. Starting with 300 candidate designs, three-dimensional computational fluid dynamics simulations predict the thermal-hydraulic performance of cold plate subsections. The highest performing geometries are evaluated with high fidelity simulations. Four cold plates are manufactured for experiments: three with diamond-shaped pin fins and one with straights fins for comparison purposes. The cold plates are fabricated from copper-tungsten (CuW), copper (Cu), or aluminum-silicon-magnesium alloy (AlSi10Mg). The diamond-shaped pin fins achieve a roughly 15 % lower thermal resistance compared to the conventional straight fin microchannel. The highest performing design achieves a chip-to-coolant (including thermal interface material) thermal resistance of 9.0 K/kW in CuW and 6.9 K/kW in Cu under a 1 kW heat load with an inlet-to-outlet pressure drop of 9.0 kPa and water as the working fluid. This work demonstrates ultra-low thermal resistance and pressure drop cold plates for large die, high heat load applications, and shows that CuW is an attractive cold plate material for improved reliability in next generation data center cooling.

Coefficient of thermal expansion↗
DOE OSTI2026

Mechanism of Vapor-Phase Infiltration of Organometallic Hf in Poly(Methyl Methacrylate) for Hybrid Resist Applications

Inorganic–organic hybrid thin films synthesized by vapor-phase infiltration (VPI) of metal oxides into organic photoresists, such as poly(methyl methacrylate) (PMMA), have recently demonstrated their utility in extreme ultraviolet lithography, critical for angstrom-era semiconductor device miniaturization. Hafnium oxide infiltration has been reported recently for this purpose, but its detailed VPI mechanism has remained largely unexplored. In this study, we investigated the VPI characteristics and mechanisms of tetrakis(dimethylamido)hafnium (TDMAHf)─the hafnium precursor predominantly used for VPI in the field─into PMMA and examined its impact on electron-beam lithography (EBL) exposure behavior. VPI was performed at temperatures ranging from 85 to 150 °C, with chemical interactions characterized using infrared reflection-absorption spectroscopy, and resist patterning performance was evaluated through EBL dose-sensitivity assessments. The results indicate that TDMAHf forms a reversible adduct with PMMA at temperatures up to 120 °C, whereas at 150 °C, covalent bond formation occurs, most likely via dealkylation that leads to acetate formation. EBL studies reveal that resist sensitivity is influenced by both infiltration temperature and developer selection, with aqueous isopropyl alcohol development demonstrating enhanced sensitivity compared to organic solvent-based development. The optimized infiltration protocol at 120 °C ensures a uniform inorganic distribution without compromising resist dissolution. These findings not only help refine hybrid resist patterning performance but also offer insights potentially applicable to the VPI of other homoleptic metal-amide organometallic VPI precursors that include TDMA ligands.

36 MATERIALS SCIENCE↗
DOE OSTI2025

In Situ Analysis of Electron-Induced Chemical Transformations in Vapor-Phase-Synthesized Al-Based Inorganic–Organic Hybrid Thin Films for EUV Resist Platform

The rapid advancement and stringent requirements of extreme ultraviolet (EUV) lithography technology necessitate the development of advanced photoresist systems for next-generation microelectronics. Recent studies have demonstrated that inorganic-based hybrid photoresists offer notable improvements in EUV sensitivity, etch resistance, and greater insusceptibility to pattern collapse compared to their purely organic counterparts. However, variations in the synthesis/coating approaches and chemistry of inorganic–organic photoresists can result in distinct exposure mechanisms. In this work, an Al-based hybrid thin film resist system synthesized via molecular (atomic) layer deposition (MLD or MALD) is explored, focusing on its electron-beam and EUV patterning mechanisms. The Al-based hybrid thin films are deposited using trimethylaluminum (TMA) and the organic precursor hydroquinone, exhibiting a saturated growth rate within the temperature range of 150–200°C. In diluted tetramethylammonium hydroxide (TMAH)-based developer solutions, the electron-irradiated Al-based hybrid thin film system behaves as a negative tone resist, achieving a sensitivity of 10.4 mC/cm 2 at 0.1 kV electron beam lithography (EBL). Chemical changes induced by electron exposure are also analyzed in this study using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and a unique infrared spectroscopy setup, revealing the potential cross-linking pathways. To further correlate the electron-induced chemical transformations with those mediated by EUV irradiations, a combination of X-ray photoemission electron microscopy/low-energy electron microscopy (XPEEM/LEEM) system is also employed. In conclusion, this study provides critical insights into the mechanisms underlying solubility switching and contributes to the design of advanced resist materials for EUV lithography.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Minimizing Interfacial Resistance between Polymer Electrolytes and Metal Electrodes Using Applied Current

Reducing the interfacial resistance between different phases in electrochemical systems is crucial for enabling practical applications. In this work, we proposed a process for reducing the interfacial resistance between polymer electrolytes and metal electrodes. Thus far in the literature, the lowest interfacial resistance reported in these systems is 15 Ω·cm2. In this study, assembled and preconditioned symmetric cells with lithium–indium alloy electrodes showed similar values. The current through the cell was increased in steps up to the limiting current. This resulted in a permanent decrease of the interfacial resistance to values as low as 1 Ω·cm2, a value that is comparable to that of optimized lithium-ion batteries. The proposed process is general, and it could be applied to any combination of polymer electrolytes and metal electrodes.

Lee, Jaeyong↗
DOE OSTI2022

Activating alternative transport modes in a multidrug resistance efflux pump to confer chemical susceptibility

Small multidrug resistance (SMR) transporters contribute to antibiotic resistance through proton-coupled efflux of toxic compounds. Previous biophysical studies of the E. coli SMR transporter EmrE suggest that it should also be able to perform proton/toxin symport or uniport, leading to toxin susceptibility rather than resistance in vivo. Here we show EmrE does confer susceptibility to several previously uncharacterized small-molecule substrates in E. coli, including harmane. In vitro electrophysiology assays demonstrate that harmane binding triggers uncoupled proton flux through EmrE. Assays in E. coli are consistent with EmrE-mediated dissipation of the transmembrane pH gradient as the mechanism underlying the in vivo phenotype of harmane susceptibility. Furthermore, checkerboard assays show this alternative EmrE transport mode can synergize with some existing antibiotics, such as kanamycin. These results demonstrate that it is possible to not just inhibit multidrug efflux, but to activate alternative transport modes detrimental to bacteria, suggesting a strategy to address antibiotic resistance.

59 BASIC BIOLOGICAL SCIENCES↗