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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 1,261 records · Page 70
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Impact of Organic and Volatile Compounds in Produced Water from Unconventional Reservoirs on Direct Contact Membrane Distillation Permeate Quality

The expansion of oil and gas extraction from unconventional reservoirs has led to an increase in the amount of produced water that has to be managed by this industry. Direct contact membrane distillation (DCMD) is a promising technology for treatment of produced water to enable water recovery and reduce the environmental footprint of this industry. The feasibility of DCMD for the treatment of highly saline produced water from the Permian Basin in TX with commercially available polyethylene and polytetrafluoroethylene membranes was evaluated in this study. An increase in water recovery by a DCMD system operated in the batch (concentrating) mode led to an increase in permeate conductivity. Partial removal of organic compounds from the produced water by biodegradation, chemical oxidation, and/or activated carbon adsorption could not resolve deterioration in permeate quality, and none of the organics observed in the permeate contributed to its conductivity. The observed increase in permeate conductivity was attributed to the passage of ammonia vapor from the feed side followed by protonation on the permeate side. Furthermore, this study revealed that permeate conductivity may not always be a reliable indicator of membrane wetting and underscores the importance of understanding the interactions between specific solutes and membrane materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Identification and Mechanistic Understanding of Dihydroorotate Dehydrogenase Point Mutations in Plasmodium falciparum that Confer in Vitro Resistance to the Clinical Candidate DSM265

Malaria is one of the most challenging human infectious diseases, and both prevention and control have been hindered by the development of Plasmodium falciparum resistance to existing therapies. Several new compounds with novel mechanisms are in clinical development for the treatment of malaria, including DSM265, an inhibitor of Plasmodium dihydroorotate dehydrogenase. To explore the mechanisms by which resistance might develop to DSM265 in the field, we selected for DSM265-resistant P. falciparum parasites in vitro. Any of five different amino acid changes led to reduced efficacy on the parasite and to decreased DSM265 binding to P. falciparum DHODH. The DSM265-resistant parasites retained full sensitivity to atovaquone. All but one of the observed mutations were in the DSM265 binding site, and the remaining C276F was in the adjacent flavin cofactor site. The C276F mutation was previously identified in a recrudescent parasite during a Phase IIa clinical study. We confirmed that this mutation (and the related C276Y) accounted for the full level of observed DSM265 resistance by regenerating the mutation using CRISPR/Cas9 genome editing. X-ray structure analysis of the C276F mutant enzyme showed that conformational changes of nearby residues were required to accommodate the larger F276 residue, which in turn led to a restriction in the size of the DSM265 binding pocket. These findings underscore the importance of developing DSM265 as part of a combination therapy with other agents for successful use against malaria.

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

GNE-886: A Potent and Selective Inhibitor of the Cat Eye Syndrome Chromosome Region Candidate 2 Bromodomain (CECR2)

The biological function of bromodomains, epigenetic readers of acetylated lysine residues, remains largely unknown. Herein we report our efforts to discover a potent and selective inhibitor of the bromodomain of cat eye syndrome chromosome region candidate 2 (CECR2). Screening of our internal medicinal chemistry collection led to the identification of a pyrrolopyridone chemical lead, and subsequent structure-based drug design led to a potent and selective CECR2 bromodomain inhibitor (GNE-886) suitable for use as an in vitro tool compound.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Quantitative Profiling of Protein S-Glutathionylation Reveals Redox-Dependent Regulation of Macrophage Function During Nanoparticle-Induced Oxidative Stress

Engineered nanoparticles (ENPs) are emerging functional materials increasingly utilized for commercial and medical applications. Due to the potential hazard effects of ENPs to human health, it is significant to assess and understand the underlying mechanisms of nanotoxicity. Here, we investigate protein S-glutathionylation (SSG) as an underlying regulatory mechanism for ENP-induced oxidative stress in macrophages by applying a recently developed quantitative redox proteomics approach for site-specific measurements of SSG. Three high-volume production ENPs (SiO 2 , Fe 3 O 4 and CoO) were selected as representative ENPs with low, moderate, and high reactive oxygen species (ROS) activity, respectively. Among these nanoparticles, we observe that CoO led to the most significant dose-dependent oxidative stress and increase of protein SSG modifications in macrophages. Our site-specific SSG changes highlighted a broad set of redox sensitive proteins and their specific Cys residues potentially implicated in stress response. Functional analysis revealed that the most significantly enriched functional categories for SSG-modified proteins were stress response, cellular structure change, and cell death or survival. Moreover, ENPs-induce oxidative stress levels (CoO > Fe 3 O 4 > SiO 2 ) were found to correlate well with the levels of impairment of macrophage phagocytic activity and the overall degrees of increases in SSG. RNA silencing knockdown experiment of glutaredoxin 1 (Grx1) also led to a decreased phagocytic activity in macrophages, which suggested a regulatory role of SSG in phagocytosis. Together, the results provided valuable insights of protein SSG as a potential regulatory mechanism in response to nanomaterial-induced oxidative stress and immunity dysfunction.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Chemo-Mechanical Behavior and Stability of High-Loading Cathodes in Solid-State Batteries

Solid-state batteries can offer higher energy density and improved safety compared to lithium ion batteries, which use flammable liquid electrolytes. Increasing the ratio of cathode active materials in composite cathodes enhances the energy density and reduces manufacturing costs. Changes in the ratio of cathode active materials alter the microstructure and chemo-mechanical response of a cathode during operation. Understanding the relationship between composition, microstructure, and chemo-mechanical interactions is critical for optimizing solid-state cathodes. Here, in this study, we engineered composite cathodes with varying ratios of LiNi 0.8 Co 0.1 Mn 0.1 O 2 and Li 6 PS 5 Cl to systematically investigate the role of microstructural evolution in long-term chemo-mechanical transformations. Chemo-mechanical stresses resulting from the volume changes of the cathode active materials led to degradation mechanisms, such as fracture and interfacial delamination. Active material fracture and delamination led to underutilization of active material and significant capacity decay during cycling. Coatings that suppress active material-active material interactions during cycling may aid in suppressing the generation of local stress hotspots.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Modification at the C2'-O-Position with 2-Methylbenzothiophene Induces Unique Structural Changes and Thermal Transitions on Duplexes of RNA and DNA

Oligonucleotides can be chemically modified for a variety of applications that include their use as biomaterials, in therapeutics, or as tools to understand biochemical processes, among others. This work focuses on the functionalization of oligonucleotides of RNA and DNA (12- or 14-nucleotides long) with methylbenzothiophene (BT), at the C2'-O-position, which led to unique structural features. Circular dichroism (CD) analyses showed that positioning the BT units on one strand led to significant thermal destabilization, while duplexes where each strand contained 4-BT rings formed a distinct arrangement with cooperativity/interactions among the modifications (evidenced from the appearance of a band with positive ellipticity at 235 nm). Interestingly, the structural arrays displayed increased duplex stabilization (>10 °C higher than the canonical analogue) as a function of [Na + ] with an unexpected structural rearrangement at temperatures above 50 °C. Density functional theory–polarizable continuum model (DFT-PCM) calculations were carried out, and the analyses were in agreement with induced structural changes as a function of salt content. A model was proposed where the hydrophobic surface allows for an internal nucleobase rearrangement into a more thermodynamically stable structure, before undergoing full denaturation, with increased heat. While this behavior is not common, B- to Z-form duplex transitions can occur and are dependent on parameters that were probed in this work, i.e., temperature, nature of modification, or ionic content. To take advantage of this phenomenon, we probed the ability of the modified duplexes to be recognized by Zα (an RNA binding protein that targets Z-form RNA) via electrophoretic analysis and CD. Interestingly, the protein did not bind to canonical duplexes of DNA or RNA; however, it recognized the modified duplexes, in a [monovalent/divalent salt] dependent manner. Overall, the findings describe methodology to attain unique structural motifs of modified duplexes of DNA or RNA, and control their behavior as a function of salt concentration. While their affinity to RNA binding proteins, and the corresponding mechanism of action, requires further exploration, the tunable properties can be of potential use to study this, and other, types of modifications. The novel arrays that formed, under the conditions described herein, provide a useful way to explore the structure and behavior of modified oligonucleotides, in general.

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

Tunable Light-Emitting Diodes Utilizing Quantum-Confined Layered Perovskite Emitters

Organic–inorganic perovskites have been shown to have excellent optoelectronic properties. Further, layered perovskites have been demonstrated, utilizing quantum confinement to achieve emission blue-shifted from the bulk band gap. Here, we tune this blue-shift to build LEDs that span the visible spectrum. We demonstrate that electroluminescence from red-shifted layers dominates emission from mixed-thickness devices and that the addition of excess ligand is necessary to drive emission toward blue-shifted layers. By tuning the thickness of the layers, we build LEDs with blue emission utilizing the lead bromide system and orange emission utilizing the lead iodide system. Lastly, we demonstrate that these materials suffer reversible degradation under an applied electric field. The spectrally narrow emission, combined with the favorable electronic properties of perovskite materials and access to shorter emission wavelengths through quantum confinement, demonstrates the promise of these materials as a new platform for low-cost, high-performance light-emitting devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Physiochemical Characterization of Lignocellulosic Biomass Dissolution by Flowthrough Pretreatment

Comprehensive understanding of biomass solubilization chemistry in aqueous pretreatment such as water-only and dilute acid flowthrough pretreatment is of fundamental importance to achieve the goal of valorizing biomass to fermentable sugars and lignin for biofuels production. In this study, poplar wood was flowthrough pretreated by water-only or 0.05% (w/w) sulfuric acid at different temperatures (220-270 °C), flow rate (25 mL/min), and reaction times (8-90 min), resulting in significant disruption of the lignocellulosic biomass. Ion chromatography (IC), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) analysis, and solid state cross-polarization/magic angle spinning (CP/MAS) 13C nuclear magnetic resonance (NMR) spectroscopy were applied to characterize the pretreated biomass whole slurries in order to reveal depolymerization as well as solubilization mechanism and identify unique dissolution structural features during these pretreatments. Results showed temperature-dependent cellulose decrystallization in flowthrough pretreatment. Crystalline cellulose was completely disrupted, and mostly converted to amorphous cellulose and oligomers by water-only operation at 270 °C for 10 min and by 0.05 wt % H2SO4 flowthrough pretreatment at 220 °C for 12 min. Flowthrough pretreatment with 0.05% (w/w) H2SO4 led to a greater disruption of structures in pretreated poplar at a lower temperature compared to water-only pretreatment.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

Macromolecular Crowding Induces Spatial Correlations That Control Gene Expression Bursting Patterns

Recent superresolution microscopy studies in E. coli demonstrate that the cytoplasm has highly variable local concentrations where macromolecular crowding plays a central role in establishing membrane-less compartmentalization. This spatial inhomogeneity significantly influences molecular transport and association processes central to gene expression. Yet, little is known about how macromolecular crowding influences gene expression bursting—the episodic process where mRNA and proteins are produced in bursts. Here, we simultaneously measured mRNA and protein reporters in cell-free systems, showing that macromolecular crowding decoupled the well-known relationship between fluctuations in the protein population (noise) and mRNA population statistics. Crowded environments led to a 10-fold increase in protein noise even though there were only modest changes in the mRNA population and fluctuations. Instead, cell-like macromolecular crowding created an inhomogeneous spatial distribution of mRNA (“spatial noise”) that led to large variability in the protein production burst size. As a result, the mRNA spatial noise created large temporal fluctuations in the protein population. Furthermore, these results highlight the interplay between macromolecular crowding, spatial inhomogeneities, and the resulting dynamics of gene expression, and provide insights into using these organizational principles in both cell-based and cell-free synthetic biology.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2018

CO-Bridged H-Cluster Intermediates in the Catalytic Mechanism of [FeFe]-Hydrogenase CaI

The [FeFe]-hydrogenases ([FeFe] H 2 ases) catalyze reversible H 2 activation at the H-cluster, which is composed of a [4Fe-4S] H subsite linked by a cysteine thiolate to a bridged, organometallic [2Fe-2S] ([2Fe] H ) subsite. Profoundly different geometric models of the H-cluster redox states that orchestrate the electron/proton transfer steps of H 2 bond activation have been proposed. We have examined this question in the [FeFe] H 2 ase I from Clostridium acetobutylicum (CaI) by Fourier-transform infrared (FTIR) spectroscopy with temperature annealing and H/D isotope exchange to identify the relevant redox states and define catalytic transitions. One-electron reduction of H ox led to formation of H red H + ([4Fe-4S] H 2+ -Fe I -Fe I ) and H red ' ([4Fe-4S] H 1+ -Fe II -Fe I ), with both states characterized by low frequency μ-CO IR modes consistent with a fully bridged [2Fe] H . Similar μ-CO IR modes were also identified for H red H + of the [FeFe] H 2 ase from Chlamydomonas reinhardtii (CrHydA1). The CaI proton-transfer variant C298S showed enrichment of an H/D isotope-sensitive μ-CO mode, a component of the hydride bound H-cluster IR signal, H hyd . Equilibrating CaI with increasing amounts of NaDT, and probed at cryogenic temperatures, showed H red H + was converted to H hyd . Over an increasing temperature range from 10 to 260 K catalytic turnover led to loss of Hhyd and appearance of H ox , consistent with enzymatic turnover and H 2 formation. The results show for CaI that the μ-CO of [2Fe] H remains bridging for all of the 'H red ' states and that H red H + is on pathway to H hyd and H 2 evolution in the catalytic mechanism. Here, this provides a blueprint for designing small molecule catalytic analogs

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

Decreasing the Rate of Metabolic Ketone Reduction in the Discovery of a Clinical Acetyl-CoA Carboxylase Inhibitor for the Treatment of Diabetes

We found that Acetyl-CoA carboxylase (ACC) inhibitors offer significant potential for the treatment of type 2 diabetes mellitus (T2DM), hepatic steatosis, and cancer. However, the identification of tool compounds suitable to test the hypothesis in human trials has been challenging. An advanced series of spirocyclic ketone-containing ACC inhibitors recently reported by Pfizer were metabolized in vivo by ketone reduction, which complicated human pharmacology projections. Here, we disclose that this metabolic reduction can be greatly attenuated through introduction of steric hindrance adjacent to the ketone carbonyl. Incorporation of weakly basic functionality improved solubility and led to the identification of 9 as a clinical candidate for the treatment of T2DM. Phase I clinical studies demonstrated dose-proportional increases in exposure, single-dose inhibition of de novo lipogenesis (DNL), and changes in indirect calorimetry consistent with increased whole-body fatty acid oxidation. This demonstration of target engagement validates the use of compound 9 to evaluate the role of DNL in human disease.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2013

Photooxidation and Photodesorption in the Photochemistry of Isobutene on TiO2(110)

The photochemistry of isobutene was examined on the rutile TiO2(110) surface as a function of the surface pretreatment condition and irradiation temperature using temperature programmed desorption (TPD) and photon stimulated desorption (PSD). Isobutene adsorbs molecularly on the clean TiO2(110) surface without detectable thermal decomposition. Preadsorption of oxygen, either as atoms or chemisorbed molecules, did not promote thermal reactions with isobutene, but instead blocked isobutene adsorption sites. Ultraviolet (UV) light irradiation of isobutene adsorbed on the clean surface led to depletion through photodesorption without significant photodecomposition. Isobutene PSD yields increased with increasing surface temperature suggesting that activated molecules sample their physisorbed potential energy surface during photodesorption. Preadsorption of oxygen promoted partial photooxidation of adsorbed isobutene to acetone, methacrolein and isobutanal. Acetone was only detected when molecular oxygen was present, indicating that O2 addition occurred across the C=C bond. In contrast, results from use of D6-isobutene indicated that coadsorption with either O adatoms or O2 molecules led to photochemical production of methacrolein (and likely isobutanal) through C-H bond cleavage on a methyl group. Irradiation an adlayer comprised of isobutene isolated from the surface by 1 ML of preadsorbed O2 showed the most photoconversion of isobutene, which suggests that photoactivation of adsorbed O2 is a key step in partial photooxidation of isobutene. Comparison of the isobutene PSD and oxidation product yields as a function of surface temperature between 20 and 120 K indicates a competition between photooxidation and photodesorption that varies with temperature. ‘Direct’ charge transfer events between isobutene and the surface, favored at higher temperature, compete with partial oxidation pathways initiated by ‘indirect’ activation of isobutene by O2, which is favored at low temperature. Access of O2 to the surface is critical to achieving desired isobutene photooxidation rates and products, and isobutene photodesorption may provide a means of regulating the isobutene surface coverage. Work reported here was supported by the U.S. Department of Energy, Office of Basic Energy Science, Division of Chemical Sciences, Geosciences, and Biosciences, and performed in the Williams R. Wiley Environmental Molecular Science Laboratory (EMSL), a Department of Energy user facility funded by the Office of Biological and Environmental Research. Pacific Northwest National Laboratory is a multiprogram national laboratory operated for the U.S. Department of Energy by the Battelle Memorial Institute under contract DEAC05-76RL01830.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2012

Solvothermal Synthesis of Ultrasmall Tungsten Oxide Nanoparticles

The synthesis of catalytically useful, ultrasmall oxide nanoparticles (NPs) of group 5 and 6 metals is not readily achievable through reported methods. Here in this work, we introduce a one-pot, two-precursor synthesis route to <2 nm MO x NPs in which a polyoxometalate salt is decomposed thermally in a high-boiling organic solvent oleylamine. The use of ammonium metatungstate resulted in oleylamine-coated, crystalline WO x NPs at consistently high yields of 92 ± 5%. The semicrystalline NPs contained 20–36 WO x structural units per particle, as determined from aberration-corrected high-resolution scanning transmission electron microscopy, and an organic coating of 16–20 oleylamine molecules, as determined by thermogravimetric analysis. The NPs had a mean size of 1.6 ± 0.3 nm, as estimated from atomic force microscopy and small-angle X-ray scattering measurements. Carrying out the synthesis in the presence of organic oxidant trimethylamine N-oxide led to smaller WO x NPs (1.0 ± 0.4 nm), whereas the reductant 1,12-dodecanediol led to WO x nanorods (4 ± 1 nm × 20 ± 5 nm). Lastly, these findings provide a new method to control the size and shape of transition metal oxide NPs, which will be especially useful in catalysis.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Streamflow in the Columbia River Basin: Quantifying Changes Over the Period 1951-2008 and Determining the Drivers of Those Changes

Trend, detection, and attribution analyses were performed using naturalized streamflow observations and routed land surface model runoff for 10 subbasins in the Columbia River Basin during water years 1951–2008. The Energy Exascale Earth System land-surface model (ELM) version 1.0 and the Routing Application for Parallel computatIon of Discharge (RAPID) routing model were used to conduct semi-factorial simulations driven by multiple sets of bias-corrected forcing data sets. Four main potential drivers, including climate change (CLMT), CO 2 concentration (CO 2 ), nitrogen deposition (NDEP), and land use and land cover change (LULCC), were analyzed during the assessment. All subbasins showed significant (α = 0.10) declines in the observed amount of annual total streamflow, except for the Middle and Upper Snake and Upper Columbia Subbasins. These declines were led by significant decreases in June–October streamflow, which also directly led to significant decreases in peak and summer streamflow. Except for the Snake River Subbasins, LULCC had the same pattern of declines in monthly streamflow, but the period was shifted to May–September. NDEP also had significant trends in June–October; however, rather than decreases, the trends showed significant increases in streamflow. While there were significant trends in CO 2 , NDEP, and LULCC, their signals of change were weak in comparison to the signal in CLMT and the natural internal variability found in streamflow. Overall, the detection and attribution analysis showed that the historical changes found in annual total, center of timing of, and summer mean streamflow could be attributed to changing climate and variability.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2019

Hyporheic Zone Microbiome Assembly Is Linked to Dynamic Water Mixing Patterns in Snowmelt-Dominated Headwater Catchments

We report that terrestrial and aquatic elemental cycles are tightly linked in upland fluvial networks. Biotic and abiotic mineral weathering, microbially mediated degradation of organic matter, and anthropogenic influences all result in the movement of solutes (e.g., carbon, metals, and nutrients) through these catchments, with implications for downstream water quality. Within the river channel, the region of hyporheic mixing represents a hot spot of microbial activity, exerting significant control over solute cycling. To investigate how snowmelt-driven seasonal changes in river discharge affect microbial community assembly and carbon biogeochemistry, depth-resolved pore water samples were recovered from multiple locations around a representative meander on the East River near Crested Butte, CO, USA. Vertical temperature sensor arrays were also installed in the streambed to enable seepage flux estimates. Snowmelt-driven high river discharge led to an expanding zone of vertical hyporheic mixing and introduced dissolved oxygen into the streambed that stimulated aerobic microbial respiration. These physicochemical processes contributed to microbial communities undergoing homogenizing selection, in contrast to other ecosystems where lower permeability may limit the extent of mixing. Conversely, lower river discharge conditions led to a greater influence of upwelling groundwater within the streambed and a decrease in microbial respiration rates. Finally, associated with these processes, microbial communities throughout the streambed exhibited increasing dissimilarity between each other, suggesting that the earlier onset of snowmelt and longer periods of base flow may lead to changes in the composition (and associated function) of streambed microbiomes, with consequent implications for the processing and export of solutes from upland catchments.

58 GEOSCIENCES↗
DOE OSTI2021

Unraveling the Combined Effects of Ice and Permafrost on Arctic Delta Morphodynamics

Arctic delta channel dynamics and coastal deposition patterns are uniquely affected by ice and permafrost. Building on previous experiments that documented the individual effects of ice and permafrost, we conducted new numerical modeling experiments to examine the combined influences of ice thickness and permafrost erodibility. We quantified the effects of ice, permafrost, and their combination on channel migration, avulsion, and persistence; onshore and nearshore deposition; and large-scale delta morphology. Both ice and permafrost limited channel mobility, enhanced overbank deposition, and roughened shorelines. Thick ice increased offshore channel incision and sediment delivery. Permafrost stabilized channels and focused deposition that led to enhanced channel levee development. The increased levee deposition limited widespread channel infilling leading to the preservation of abandoned channels. Levee growth was enhanced by overbank flooding due to ice-driven changes in water surface elevations. Furthermore, this flooding led to more extensive levees on deltas with both ice and permafrost compared to deltas with only permafrost. Ice also preserved small channels, leading to size-dependent channel persistence: the presence of ice in the channels reduced the fraction of time small channels remained active relative to larger channels. Resistant permafrost damped this effect, as smaller and more distal channels were active earlier in the flood on deltas with resistant permafrost likely due to the smaller number of channels on permafrost-laden deltas. Finally, our results suggest that the loss of both ice and permafrost will increase channel mobility, decrease overbank flooding, increase shoreline progradation rates, and decrease offshore transport of riverine fluxes.

58 GEOSCIENCES↗