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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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All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Unraveling the Luminescence Quenching Mechanism in Strong and Weak Quantum-Confined CsPbBr 3 Triggered by Triarylamine-Based Hole Transport Layers

Luminescence quenching by hole transport layers (HTLs) is one of the major issues in developing efficient perovskite light-emitting diodes (PeLEDs), particularly prominent in blue-emitting devices. While a variety of material systems have been used as interfacial layers, the origin of such quenching and the type of interactions between perovskites and HTLs are still ambiguous. Here, we present a systematic investigation of the luminescence quenching of CsPbBr 3 by a commonly employed hole transport polymer, Poly(9,9-dioctylfluorene-alt-N-(4-sec-butylphenyl)-diphenylamine) (TFB) in LEDs. Strong and weakly quantum-confined CsPbBr 3 (nanoplatelets (NPLs)/nanocrystals (NCs)) are rationally selected to study the quenching mechanism by considering the differences in their morphology, energy level alignments, and quantum confinement. The steady-state and time-resolved Stern-Volmer plots unravel the dominance of dynamic and static quenching at lower and higher concentrations of TFB, respectively, with maximum quenching efficiency of 98%. The quenching rate in NCs is faster than in NPLs owing to their longer PL lifetimes and weak quantum confinement. The ultrafast transient absorption results support these dynamics and rule out the involvement of Forster or Dexter energy transfer. Finally, the 1D 1 H and 2D NOESY NMR study confirms the exchange of native ligands at the NCs surface with TFB, leading to dark CsPbBr 3 -TFB ensemble formation accountable for luminescence quenching. This highlights the critical role of the triarylamine functional group on TFB (also the backbone of many HTLs) in the quenching process. These results shed light on the underlying reasons for the luminescence quenching in PeLEDs and will help to choose the interfacial layers rationally for developing efficient LEDs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

A chemical genetic screen uncovers a small molecule enhancer of the N-acylethanolamine degrading enzyme, fatty acid amide hydrolase, in Arabidopsis

N-Acylethanolamines (NAEs) are a group of fatty acid amides that play signaling roles in diverse physiological processes in eukaryotes. We used fatty acid amide hydrolase (FAAH) degrades NAE into ethanolamine and free fatty acid to terminate its signaling function. In animals, chemical inhibitors of FAAH for therapeutic treatment of pain and as tools to probe deeper into biochemical properties of FAAH. In a chemical genetic screen for small molecules that dampened the inhibitory effect of N-lauroylethanolamine (NAE 12:0) on Arabidopsis thaliana seedling growth, we identified 6-(2-methoxyphenyl)-1,3-dimethyl-5-phenyl-1H-pyrrolo[3,4-d]pyrimidine-2,4(3 H,6 H)-dione (or MDPD). MDPD alleviated the growth inhibitory effects of NAE 12:0, in part by enhancing the enzymatic activity of Arabidopsis FAAH (AtFAAH). In vitro, biochemical assays showed that MDPD enhanced the apparent Vmax of AtFAAH but did not alter the affinity of AtFAAH for its NAE substrates. Furthermore, structural analogs of MDPD did not affect AtFAAH activity or dampen the inhibitory effect of NAE 12:0 on seedling growth indicating that MDPD is a specific synthetic chemical activator of AtFAAH. Our study demonstrates the feasibility of using an unbiased chemical genetic approach to identify new pharmacological tools for manipulating FAAH- and NAE-mediated physiological processes in plants.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

An europium( iii ) diglycolamide complex: insights into the coordination chemistry of lanthanides in solvent extraction

The synthesis, stoichiometry, and structural characterization of a homoleptic, cationic europium(III) complex with three neutral tetraalkyldiglycolamide ligands are reported. The tri(bismuth tetrachloride)tris(N,N,N',N'-tetra-n-octyldiglycolamide)Eu salt, [Eu(TODGA)3][(BiCl4)3] obtained from methanol was examined by Eu L3-edge X-ray absorption spectroscopy (XAS) to reveal an inner-sphere coordination of Eu3+ that arises from 9 O atoms and two next-nearest coordination spheres that arise from 6 carbon atoms each. A structural model is proposed in which each TODGA ligand with its O[double bond, length as m-dash]Ca–Cb–O–Cb–Ca[double bond, length as m-dash]O backbone acts as a tridentate O donor, where the two carbonyl O atoms and the one ether O atom bond to Eu3+. Given the structural rigidity of the tridentate coordination motif in [Eu(TODGA)3]3+ with six 5-membered chelate rings, the six Eu–Ca and six Eu–Cb interactions are readily resolved in the EXAFS (extended X-ray absorption fine structure) spectrum. The three charge balancing [BiCl4]- anions are beyond the cationic [Eu(TODGA)3]3+ cluster in an outer sphere environment that is too distant to be detected by XAS. Despite their sizeable length and propensity for entanglement, the four n-octyl groups of each TODGA (for a total of twelve) do not perturb the Eu3+ coordination environment over that seen from previously reported single-crystal structures of tripositive lanthanide (Ln3+) complexes with tetraalkyldiglycolamide ligands (of the same 1 : 3 metal-to-ligand ratio stoichiometry) but having shorter i-propyl and i-butyl groups. The present results set the foundation for understanding advanced solvent extraction processes for the separation of the minor, tripositive actinides (Am, Cm) from the Ln3+ ions in terms of the local structure of Eu3+ in a solid state coordination complex with TODGA.

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

New route to the fabrication of nanocrystalline diamond films

Nanocrystalline diamond (NCD) thin films offer applications in various fields, but the existing synthetic approaches are cumbersome and destructive. A major breakthrough has been achieved by our group in the direction of a non-destructive, scalable, and economic process of NCD thin-film fabrication. Here, we report a cheap precursor for the growth of nanocrystalline diamond in the form of paraffin wax. We show that NCD thin films can be fabricated on a copper support by using simple, commonplace paraffin wax under reaction conditions of Hot Filament Chemical Vapor Deposition (HFCVD). Surprisingly, even the presence of any catalyst or seeding that has been conventionally used in the state-of-the-art is not required. The structure of the obtained films was analyzed by scanning electron microscopy and transmission electron microscopy. Raman spectroscopy and electron energy-loss spectroscopy recorded at the carbon K-edge region confirm the presence of nanocrystalline diamond. The process is a significant step towards cost-effective and non-cumbersome fabrication of nanocrystalline diamond thin films for commercial production.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Structural and magnetic studies of nanocrystalline Y{sub 2}Ir{sub 2}O{sub 7}

In this paper, we discuss synthesis of Y{sub 2}Ir{sub 2}O{sub 7} nanoparticles via chemical solution process. Structural analysis shows single cubic phase with Fd-3m space group symmetry. The particle size and distribution were studied by Transmission Electron Microscopy experiments. The average particle size turns out to be 50nm, which is in good agreement with the XRD results. Magnetic characterization shows no evidence of long range ordering even in presence of strong correlations.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2019

Vibronic fingerprint of singlet fission in hexacene

Singlet fission has the great potential to overcome the Shockley–Queisser thermodynamic limit and thus promotes solar power conversion efficiency. However, the current limited understandings of detailed singlet fission mechanisms hinder a further improved design of versatile singlet fission materials. In the present study, we combined ultrafast transient infrared spectroscopy with ab initio calculations to elucidate the roles played by the vibrational normal modes in the process of singlet fission for hexacene. Our transient infrared experiments revealed three groups of vibrational modes that are prominent in vibronic coupling upon photoexcitation. Through our computational study, those normal modes with notable Franck-Condon shifts have been classified as ring-twisting modes near 1300.0 cm−1, ring-stretching modes near 1600.0 cm−1, and ring-scissoring modes near 1700.0 cm−1. Experimentally, a ring-stretching mode near 1620.0 cm−1 exhibits a significant blue-shift of 4.0 cm−1 during singlet fission, which reaction rate turns out to be 0.59 ± 0.07 ps. More interestingly, the blue-shifted mode was also identified by our functional mode singlet fission theory as the primary driving mode for singlet fission, suggesting the importance of vibronic coupling when a correlated triplet pair of hexacene is directly converted from its first excited state singlet exciton. Our findings indicate that the ultrafast transient infrared spectroscopy, in conjunction with the nonadiabatic transition theory, is a powerful tool to probe the vibronic fingerprint of singlet fission.

Deng, Gang-Hua↗
DOE OSTI2023

Computer simulation of carbonization and graphitization of coal

Abstract This study describes computer simulations of carbonization and graphite formation, including the effects of hydrogen, nitrogen, oxygen, and sulfur. We introduce a novel technique to simulate carbonization, ‘Simulation of Thermal Emission of Atoms and Molecules (STEAM)’, designed to elucidate volatile outgassing and density variations in the intermediate material during carbonization. The investigation analyzes the functional groups that endure through high-temperature carbonization and examines the graphitization processes in carbon-rich materials containing non-carbon impurity elements. The physical, vibrational, and electronic attributes of impure amorphous graphite are analyzed, and the impact of nitrogen on electronic conduction is investigated.

Ugwumadu, C. (ORCID:0000000199207594)↗
DOE OSTI2017

Reassessing the roles of PIN proteins and anticlinal microtubules during pavement cell morphogenesis

The leaf epidermis is a biomechanical shell that influences the size and shape of the organ. Its morphogenesis is a multiscale process in which nanometer-scale cytoskeletal protein complexes, individual cells, and groups of cells pattern growth and define macroscopic leaf traits. Interdigitated growth of neighboring cells is an evolutionarily conserved developmental strategy. Understanding how signaling pathways and cytoskeletal proteins pattern cell walls during this form of tissue morphogenesis is an important research challenge. The cellular and molecular control of a lobed cell morphology is currently thought to involve PIN-FORMED (PIN)-type plasma membrane efflux carriers that generate subcellular auxin gradients. Auxin gradients were proposed to function across cell boundaries to encode stable offset patterns of cortical microtubules and actin filaments between adjacent cells. Many models suggest that long-lived microtubules along the anticlinal cell wall generate local cell wall heterogeneities that restrict local growth and specify the timing and location of lobe formation. Here we used Arabidopsis reverse genetics and multivariate long-term time-lapse imaging to test current cell shape control models. We found that neither PIN proteins nor microtubules along the anticlinal wall predict the patterns of lobe formation. In fields of lobing cells, anticlinal microtubules are not correlated with cell shape and are unstable at the time scales of cell expansion. Our analyses indicate that anticlinal microtubules have multiple functions in pavement cells, and that lobe initiation is likely controlled by complex interactions among cell geometry, cell wall stress patterns, and transient microtubule networks that span the anticlinal and periclinal walls.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Purification, crystallization and preliminary X-ray diffraction analysis of the Escherichia coli common pilus chaperone EcpB

In Escherichia coli, the common pilus (Ecp) belongs to an alternative chaperone–usher pathway that plays a major role in both early biofilm formation and host-cell adhesion. Initial attempts at crystallizing the chaperone EcpB using natively purified protein from the bacterial periplasm were not successful; however, after the isolation of EcpB under denaturing conditions and subsequent refolding, crystals were obtained at pH 8.0 using the sitting-drop method of vapour diffusion. This is the first time that this refolding strategy has been used to purify CU chaperones. Pili are key cell-surface components that allow the attachment of bacteria to both biological and abiotic solid surfaces, whilst also mediating interactions between themselves. In Escherichia coli, the common pilus (Ecp) belongs to an alternative chaperone–usher (CU) pathway that plays a major role in both early biofilm formation and host-cell adhesion. The chaperone EcpB is involved in the biogenesis of the filament, which is composed of EcpA and EcpD. Initial attempts at crystallizing EcpB using natively purified protein from the bacterial periplasm were not successful; however, after the isolation of EcpB under denaturing conditions and subsequent refolding, crystals were obtained at pH 8.0 using the sitting-drop method of vapour diffusion. Diffraction data have been processed to 2.4 Å resolution. These crystals belonged to the trigonal space group P3{sub 1}21 or P3{sub 2}21, with unit-cell parameters a = b = 62.65, c = 121.14 Å and one monomer in the asymmetric unit. Molecular replacement was unsuccessful, but selenomethionine-substituted protein and heavy-atom derivatives are being prepared for phasing. The three-dimensional structure of EcpB will provide invaluable information on the subtle mechanistic differences in biogenesis between the alternative and classical CU pathways. Furthermore, this is the first time that this refolding strategy has been used to purify CU chaperones, and it could be implemented in similar systems where it has not been possible to obtain highly ordered crystals.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Decomposition of Aromatic Compounds Relevant to Organic Electronics under Exposure to Low-Energy Electrons

The persistence of molecules to destruction under the action of low-energy (0–15 eV) electrons is investigated for a representative series of aromatic compounds of interest to organic electronics and photonics. The energy regions of the most effective interaction of free electrons with isolated molecules, which leads to the dissociative decay of molecules due to the formation of short-lived negative molecular ions unstable to fragmentation, are determined using resonance electron capture negative ion mass spectrometry. The characteristic fragmentation channels for molecular ions are revealed for some groups of compounds, and the threshold energies of the most significant fragmentation processes are estimated. Polycyclic aromatic hydrocarbons and oligophenyls are stable to the action of electrons in the electron energy range ~0–3 eV, above which these compounds are decomposed into the single channel of hydrogen atom detachment. For compounds with heterocycles (oxadiazole and maleimide derivatives) in their structure, the stability range narrows down to ~0–1 eV. Electrons with energies exceeding this range initiate the decay of molecules (anions) via various channels among which the detachment of a cyanate anion from a heterocyclic nucleus is the most intense and destructive process.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2013

Progress Report on the ISCR Pilot Test Conducted at the Former CCC/USDA Grain Storage Facility in Montgomery City, Missouri, as of April 2013

The Commodity Credit Corporation of the U.S. Department of Agriculture (CCC/USDA) is conducting an environmental investigation at the former CCC/USDA grain storage facility on the county fairgrounds in Montgomery City, Missouri, to evaluate contamination associated with the former use of grain fumigants containing carbon tetrachloride at the site. The CCC/USDA studies have identified carbon tetrachloride in the soils (primarily unconsolidated glacial tills) at concentrations that exceed the U.S. Environmental Protection Agency (EPA) regional screening level (RSL) values for this compound in residential soils (610 μg/kg) but are below the corresponding RSL for industrial soils (3,000 μg/kg). Concentrations of carbon tetrachloride greater than the EPA maximum contaminant level (MCL; 5.0 μg/L) for this contaminant in drinking water were also identified in the shallow groundwater (Argonne 2012). On the basis of these findings, remedial actions are considered necessary to mitigate the present and potential future impacts of the contamination. In cooperation with the Missouri Department of Natural Resources (MDNR), the CCC/USDA has initiated a field-scale pilot test to evaluate an in situ technology for treatment of the carbon tetrachloride contamination. In this approach, a chemical amendment consisting primarily of slow-release organic matter and zero-valent iron is employed to induce oxygen-depleted, chemically reducing conditions in the subsurface. These conditions foster the in situ chemical reduction (ISCR) of carbon tetrachloride and its degradation products (chloroform, methylene chloride, and chloromethane) via both inorganic and biologically mediated processes. The chemical amendment being used, EHC™, was developed by the Adventus Group, Freeport, Illinois, and is now manufactured and distributed by FMC Environmental Solutions, Philadelphia, Pennsylvania. With the approval of the MDNR (2012), the ISCR technology is being tested in two target areas interpreted to represent contaminant source areas. The pilot test is being implemented on behalf of the CCC/USDA by Argonne National Laboratory. Approximately 80,000 lb of the EHC material was injected by using direct-push techniques at 99 locations in the target areas, from November 9 to December 15, 2012 (Argonne 2012). To determine the geochemical effects of the pilot injections and their impact on the levels of contamination in the test areas, an extended monitoring program (Argonne 2012) is being implemented. The program includes an initial “baseline” sampling event to document pre-treatment conditions and periodic post-injection monitoring events, approximately 1, 2, 4, 6, 9, and 12 months after the completion of the injection program (Argonne 2012). This report provides a brief summary of the specific activities conducted, with a compilation of the monitoring data obtained, during the baseline sampling event (October 2012) and the first, second, and third post-injection monitoring events (in January, February, and April 2013).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2017

Institute for Clean Energy Technology Mississippi State University NSR&D Aged HEPA Filter Study Final Report

Data have demonstrated that filter media lose tensile strength and the ability to resist the effects of moisture as a function of age. Testing of new and aged filters needs to be conducted to correlate reduction of physical strength of HEPA media to the ability of filters to withstand upset conditions. Appendix C of the Nuclear Air Cleaning Handbook provides the basis for DOE’s HEPA filter service life guidance. However, this appendix also points out the variability of data, and it does not correlate performance of aged filters to degradation of media due to age. Funding awarded by NSR&D to initiate full-scale testing of aged HEPA filters addresses the issue of correlating media degradation due to age with testing of new and aged HEPA filters under a generic design basis event set of conditions. This funding has accelerated the process of describing this study via: (1) establishment of a Technical Working Group of all stakeholders, (2) development and approval of a test plan, (3) development of testing and autopsy procedures, (4) acquiring an initial set of aged filters, (5) testing the initial set of aged filters, and (6) developing the filter test report content for each filter tested. This funding was very timely and has moved the project forward by at least three years. Activities have been correlated with testing conducted under DOE-EM funding for evaluating performance envelopes for AG-1 Section FC Separator and Separatorless filters. This coordination allows correlation of results from the NSR&D Aged Filter Study with results from testing new filters of the Separator and Separatorless Filter Study. DOE-EM efforts have identified approximately 100 more filters of various ages that have been stored under Level B conditions. NSR&D funded work allows a time for rigorous review among subject matter experts before moving forward with development of the testing matrix that will be used for additional filters. The NSR&D data sets are extremely valuable in as much as establishing a selfimproving, NQA-1 program capable of advancing the service lifetime study of HEPA filters. The data and reports are available for careful and critical review by subject matter experts before the next set of filters is tested and can be found in the appendices of this final report. NSR&D funds have not only initiated the Aged HEPA Filter Study alluded to in Appendix C of the NACH, but have also enhanced the technical integrity and effectiveness of all of the follow-on testing for this long-term study.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2019

TEV-3776 Hybrid – ZIRCEX Process Demonstration Siting Study

The purpose of this technical evaluation (TEV) is to detail the siting considerations for supporting pre-conceptual design of the engineering-scale Hybrid – ZIRCEX Process (formerly known as Hybrid Uranium Recovery Demonstration [HURD]) demonstration. This process represents the first-of a kind integration of a select group of technologies meant to recover high enriched uranium (HEU) from zirconium and aluminum clad used nuclear fuel (UNF) for down-blending to produce high assay low enriched uranium (HALEU).

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2021

Preparing Distribution Utilities for the Future - Unlocking Demand-Side Management Potential: A Novel Analytical Framework

The balance of supply and demand in the power systems has traditionally been served solely through generation and network capacity planning and operations. However, with increased requirements for flexibility due to the uptake in variable renewable generation sources such as wind and solar there is a need to increased demand-side flexibility. In addition, there are increased communications and flexibility capabilities emerging on the demand-side from the adoption of advanced metering infrastructures and smart meter deployment and intelligent loads such as smart thermostats and schedulable white goods (e.g. dishwashers and washing machines). Unlocking demand-side flexibility can bring system benefits from peak load reduction bringing about generation capacity and network upgrade deferral, to reducing demand and more efficient utilization of generation and network capacity. Unlocking demand-side flexibility is an evolving process for utilities and solutions must be tailored to each specific customer group. Demand-side management (DSM) is a broad set of tools that can include demand response (both dispatchable and non-dispatchable), energy efficiency and distributed energy resources and demand-side technologies. The National Renewable Energy Laboratory (NREL), in collaboration with BSES Rajdhani Power Ltd. (BRPL) and Deloitte, examined the potential of DSM in BRPL’s service territory, developing detailed information on customer classes and willingness to participate in DSM. The study developed modeling frameworks for load analysis and the analysis tools to assess the potential of time-of-use tariffs in motivating customers to reduce their peak period energy consumption. The study shows that BRPL customers, specifically their domestic customers, are willing to participate in DSM programs and that time-of-use pricing can help BRPL reduce their peak demand and help unlock demand-side flexibility.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

Accelerated Aging of Fast Pyrolysis Bio-Oil Using Carbonyl Titration: Laboratory Analytical Procedure (LAP)

This laboratory analytical procedure covers the accelerated aging of fast pyrolysis bio-oils. Bio-oils undergo reactions that result in physical and chemical changes over time. These changes typically result in an increase in molecular weight, decrease in some functional groups such as carbonyls, and an increase in viscosity; additionally, the aging process often leads to phase separation. Studies have shown that accelerated aging of bio-oils using this method closely mimics room temperature aging for long periods of time (over 3 years). This procedure has been developed for the accelerated aging of fast pyrolysis bio-oils only. Fast pyrolysis bio-oils are more reactive than other bio-oils (e.g., catalytic fast pyrolysis) and undergo aging much more rapidly. Therefore, this procedure should only be used for fast pyrolysis bio-oil samples.

09 BIOMASS FUELS↗
DOE OSTI2022

Snowmass Theory Frontier: Astrophysics and Cosmology

We summarize progress made in theoretical astrophysics and cosmology over the past decade and areas of interest for the coming decade. This Report is prepared as the TF09 "Astrophysics and Cosmology" topical group summary for the Theory Frontier as part of the Snowmass 2021 process.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

GENESPACE tracks regions of interest and gene copy number variation across multiple genomes

The development of multiple chromosome-scale reference genome sequences in many taxonomic groups has yielded a high-resolution view of the patterns and processes of molecular evolution. Nonetheless, leveraging information across multiple genomes remains a significant challenge in nearly all eukaryotic systems. These challenges range from studying the evolution of chromosome structure, to finding candidate genes for quantitative trait loci, to testing hypotheses about speciation and adaptation. Here, we present GENESPACE, which addresses these challenges by integrating conserved gene order and orthology to define the expected physical position of all genes across multiple genomes. We demonstrate this utility by dissecting presence–absence, copy-number, and structural variation at three levels of biological organization: spanning 300 million years of vertebrate sex chromosome evolution, across the diversity of the Poaceae (grass) plant family, and among 26 maize cultivars. The methods to build and visualize syntenic orthology in the GENESPACE R package offer a significant addition to existing gene family and synteny programs, especially in polyploid, outbred, and other complex genomes.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1985

Modeling the controls of forest productivity using canopy variables

A framework is presented by which a generalized, canopy-driven model of biogeochemical cycling in forest ecosystems may be produced. Recent research results demonstrating relationships between canopy characteristics and important ecosystem processes are used to support this approach. Most relationships hold across species groups and suggest that identification of species may not be crucial. Linking this type of model to remote sensing will depend on developing the capability to measure a few key morphological and chemical parameters of whole forest canopies by reflectance characteristics.

Aber, J. D.↗