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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 613 records · Page 34
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Charge Density Mismatch is a Key Characteristic of Highly Concentrated Electrolyte Solutions and Highly Water‐Soluble Salts

Only very soluble electrolytes can form concentrated solutions. Some salts are so soluble that there are less than four water molecules per ion in saturated solution. Ions usually form clusters or networks with more than one counterion in their coordination sphere in these concentrated solutions. Do these ultraconcentrated solutions form because the counterions have high affinity for each other in liquid, or because they have a poor affinity for each other in solids? Here, in this study, this question is addressed using the valence matching principle of the bond valence model by comparing the charge density mismatch between counterions to their solubility for a series of alkali fluorides, carboxylates, and oxyanions. The solubilities are plotted against the characteristic average bond valence of the alkali, and the lowest solubilities are those where alkali and anion had matching bond valences. Conversely, the highest solubilities are those with poorly matching bond valences. Available ion-pairing constants indicate that the weakest ion-pairs are those with the largest bond valence mismatch, indicating that the large water solubilities occur despite weak ion-pairing rather than because of strong ion-pairing. Therefore, a key characteristic of highly water-soluble salts is that the counterions have mismatched charge densities.

concentrated solutions↗
DOE OSTI2018

Key Single-Atom Electrocatalysis in Metal-Organic Framework (MOF)-Derived Bifunctional Catalysts

Metal-organic framework (MOF)-derived materials have attracted increasing interest and show promising catalytic performances in many fields. Intensive efforts have been focused on the structure design and metal-site integration in MOF-derived catalysts. However, the key catalytic processes related with the metal sites in MOF-derived catalysts that dominate the electrocatalytic performance still remain obscure. Herein, we show a neglected but critical issue in the pyrolytic synthesis of MOF-derived catalysts: the coupled evolution of dual sites, that is, metallic sites and single-atom metal sites. The identification of active sites of single-atom sites from the visible particles has been elucidated through the combined X-ray spectroscopic, electron microscopic, and electrochemical studies. Interestingly, after a total removal of metallic cobalt sites, catalysts with purified single-atom metal sites show no faltering activity for either the oxygen reduction reaction (ORR) or hydrogen evolution reaction (HER), while significantly enhanced ORR selectivity is achieved; this reveals the dominant activity and selectivity contribution from single-atom electrocatalysis. The insight of the coupled evolution of dual sites and the as-demonstrated dual-site decoupling strategies open up a new routine for the design and synthesis of MOF-derived catalysts with the optimized single-atom electrocatalysis towards various electrochemical reactions.

electrocatalysis↗
DOE OSTI2026

Key Drivers for Offshore Wind Deployment in the Western United States

The western coast of the United States has abundant natural resources, including wind, sun, and water. Despite strong ocean winds, offshore wind energy (OSW) in the Western United States is in the early stages of technology development due largely to the deep water off the coast, which requires floating platforms rather than fixed‐bottom turbines. Floating OSW increases the technical difficulty of installation and thus the cost relative to both fixed‐bottom OSW and land‐based turbines. OSW is a potential generation option to help meet increasing demand on the west coast of the United States because it likely has fewer land‐use conflicts than other technologies and complements sources in the existing electricity supply by providing energy during times of high system stress. This paper examines the possible drivers and barriers to OSW deployment on the West Coast using the National Laboratory of the Rockies' state‐of‐the‐art capacity expansion model and the Regional Energy Deployment System (ReEDS) model. We use ReEDS to explore a multitude of future scenarios looking at key drivers for OSW deployment, including variations on the cost of OSW, electricity demand growth, and the availability of competing technologies to examine the factors that may play a role in OSW growth. Assuming coastal state policies such as renewable portfolio and clean energy standards remain in place, we find that OSW can play a role in meeting electricity demand and provide energy during stressful grid conditions and find that deployment from the least‐cost investment model ranges from 7.6 to 38 GW by 2045.

17 WIND ENERGY↗
DOE OSTI2022

Coral and Seawater Metagenomes Reveal Key Microbial Functions to Coral Health and Ecosystem Functioning Shaped at Reef Scale

The coral holobiont is comprised of a highly diverse microbial community that provides key services to corals such as protection against pathogens and nutrient cycling. The coral surface mucus layer (SML) microbiome is very sensitive to external changes, as it constitutes the direct interface between the coral host and the environment. Here, we investigate whether the bacterial taxonomic and functional profiles in the coral SML are shaped by the local reef zone and explore their role in coral health and ecosystem functioning. The analysis was conducted using metagenomes and metagenome-assembled genomes (MAGs) associated with the coral Pseudodiploria strigosa and the water column from two naturally distinct reef environments in Bermuda: inner patch reefs exposed to a fluctuating thermal regime and the more stable outer reefs. The microbial community structure in the coral SML varied according to the local environment, both at taxonomic and functional levels. The coral SML microbiome from inner reefs provides more gene functions that are involved in nutrient cycling (e.g., photosynthesis, phosphorus metabolism, sulfur assimilation) and those that are related to higher levels of microbial activity, competition, and stress response. In contrast, the coral SML microbiome from outer reefs contained genes indicative of a carbohydrate-rich mucus composition found in corals exposed to less stressful temperatures and showed high proportions of microbial gene functions that play a potential role in coral disease, such as degradation of lignin-derived compounds and sulfur oxidation. The fluctuating environment in the inner patch reefs of Bermuda could be driving a more beneficial coral SML microbiome, potentially increasing holobiont resilience to environmental changes and disease.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Uncertainty Estimation and Anomaly Detection in Chiral Effective Field Theory Studies of Key Nuclear Electroweak Processes

Chiral effective field theory (χEFT) is a powerful tool for studying electroweak processes in nuclei. I discuss χEFT calculations of three key nuclear electroweak processes: primordial deuterium production, proton-proton fusion, and magnetic dipole excitations of 48 Ca. Further, this article showcases χEFT’s ability to quantify theory uncertainties at the appropriate level of rigor for addressing the different precision demands of these three processes.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Measuring key Sm isotope ratios in irradiated UO 2 for use in plutonium discrimination nuclear forensics

As part of an experimental validation of a nuclear forensics methodology for Pu source reactor-type discrimination, destructive analysis has been performed here on two irradiated UO 2 pellets with different irradiation histories. Analysis has focused on measuring key Sm fission product isotope ratios used in a previously published maximum likelihood methodology to determine the most likely irradiation history of the pellets. A total of 21 Sm isotope ratios were measured within the irradiated pellets, and generally agreed within 20% of the irradiations as simulated using the Monte Carlo Radiation Transport and material depletion code, MCNP6. Results indicate the chosen approach can accurately measure the isotope ratios within 5% experimental error.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2019

Polarization-based plug-and-play measurement-device-independent quantum key distribution

Measurement-device-independent quantum key distribution (MDI-QKD) has received much attention, with the goal of overcoming all of the security loopholes caused by an imperfect detection system. We here propose a plug-and-play MDI-QKD (P&P MDI-QKD) scheme whereby an untrusted relay node, Charlie, owns a laser and sends photons to Alice and Bob. Alice (Bob) modulates the polarization of the incident photons and returns them to Charlie. Charlie uses a modified Bell state analyzer (BSA) to perform Bell state measurements (BSM). In comparison with the original version of MDI-QKD, our scheme exploits a single untrusted laser as the photon source. This makes the signal photons identical and enhances the Hong-Ou-Mandel effect. Second, because of the P&P structure, the setup can automatically eliminate the birefringence influence of the fibers, which makes the setup highly stable. Finally, our modified BSA can identify |Φ〉{sup +} and |Φ〉{sup −} of four Bell states with polarization encoding but not |Ψ〉{sup +} and |Ψ〉{sup −}. Based on practical experimental parameters, a simulation showed that the maximum theoretical secure transmission distance could reach more 280 km.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2019

Minimum shift keying based protection mode capable wavelength division multiplexed passive optical network optical overlay system

We explored the functioning of an optical overlay of multicast and unicast data streams on a survival wavelength division multiplexed passive optical network using intensity and minimum shift keying modulation for both single and multiuser. In optical line terminal, using a sinusoidal clock, optical subcarriers are generated not only to carry the multicast and unicast data streams simultaneously but also in case of fiber failure, protection mode is enabled to carry the data streams smoothly. Here, 10 Gbps downstream multicast in normal mode and unicast signals both in normal and protection mode are transmitted error-free through 30 km dispersion shifted fiber. In both the cases 10 Gbps upstream signal is modulated and sent back to the optical line terminal. For single user nearly similar power penalty is witnessed for downstream unicast as well as re-modulated upstream data in both the conditions and also when multicast data is disabled. The power penalties between single and multiuser for both the modes are found to be approximately 0.06, 0.42 and 0.7 dB for unicast MSK, multicast and upstream respectively.

36 MATERIALS SCIENCE↗
DOE OSTI2018

PtWOX11 acts as master regulator conducting the expression of key transcription factors to induce de novo shoot organogenesis in poplar

De novo shoot regeneration is a prerequisite for propagation and genetic engineering of elite cultivars in forestry. Yet, the regulatory mechanism of de novo organogenesis is poorly understood in tree species. We previously showed that WUSCHEL (WUS)-RELATED HOMEOBOX 11 (PtWOX11) of the hybrid poplar clone 84K ( Populus alba × P. glandulosa ) promotes de novo root formation. Here, we found that PtWOX11 also regulates de novo shoot regeneration in poplar. The overexpression of PtWOX11 enhanced de novo shoot formation, whereas overexpression of PtWOX11 fused with the transcriptional repressor domain ( PtWOX11-SRDX ) or reduced expression of PtWOX11 inhibited this process, indicating that PtWOX11 promotes de novo shoot organogenesis. Although PtWOX11 promotes callus formation, overexpression of PtWOX11 and PtWOX11-SRDX also produced increased and decreased numbers of de novo shoots per unit weight, respectively, implying that PtWOX11 promotes de novo shoot organogenesis partially by regulating the intrinsic mechanism of shoot development. RNA-seq and qPCR analysis further revealed that PtWOX11 activates the expression of PLETHORA1 (PtPLT1) and PtPLT2 , whose Arabidopsis paralogs establish the acquisition of pluripotency, during incubation on callus-inducing medium. Moreover, PtWOX11 activates the expression of shoot-promoting factors and meristem regulators such as CUP-SHAPED COTYLEDON2 (PtCUC2), PtCUC3, WUS and SHOOT MERISTEMLESS to fulfill shoot regeneration during incubation on shoot-inducing medium. These results imply that PtWOX11 acts as a central regulator of the expression of key genes to cause de novo shoot formation. Our studies further provide a possible means to genetically engineer economically important tree species for their micropropagation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

ADP-glucose pyrophosphorylase gene plays a key role in the quality of corm and yield of cormels in gladiolus

Starch is the main storage compound in underground organs like corms. ADP-glucose pyrophosphorylase (AGPase) plays a key role in regulating starch biosynthesis in storage organs and is likely one of the most important determinant of sink strength. Here, we identify an AGPase gene (GhAGPS1) from gladiolus. The highest transcriptional levels of GhAGPS1 were observed in cormels and corms. Transformation of GhAGPS1 into Arabidopsis rescued the phenotype of aps1 mutant. Silencing GhAGPS1 in gladiolus corms by virus-induced gene silencing (VIGS) decreased the transcriptional levels of two genes and starch content. Transmission electron microscopy analyses of leaf and corm sections confirmed that starch biosynthesis was inhibited. Corm weight and cormel number reduced significantly in the silenced plants. Taken together, these results indicate that inhibiting the expression of AGPase gene could impair starch synthesis, which results in the lowered corm quality and cormel yield in gladiolus. -- Highlights: •Cormel quantity was reduced significantly in silenced Gladiolus plants. •Corm quality was declined significantly in silenced Gladiolus plants. •Starch synthesis was inhibited in silenced Gladiolus plants.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Dihydroceramide is a key metabolite that regulates autophagy and promotes fibrosis in hepatic steatosis model

Highlights: • FFA uptake increases sphingolipids in liver cells. • Dihydroceramide product correlates with autophagosome accumulation. • Dihydroceramide impairs autophagic flux and increases lipid droplets. • Rapamycin recuperates fibrosis by recovering autophagic flux by increased dihydroceramide. Non-alcoholic fatty liver disease (NAFLD) is an increasingly common chronic liver disease worldwide. Sphingolipids are a family of lipids that play essential roles as critical regulators in metabolic disorders. Some sphingolipids are known key factors in metabolic dysfunction. However, the precise effect of dihydroceramide on NAFLD remains unknown. Here, we report how dihydroceramide in autophagosome accumulation activates fibrogenesis in human liver Chang cells treated with free fatty acids (FFA). According to LC/MS lipid profiling, FFA increased the levels of sphingolipids and triacylglycerol (TG). To demonstrate the potential role of dihydroceramide metabolism in autophagy, several sphingolipid synthesis inhibitors were used. Increased dihydroceramide led to impairment of autophagic flux, resulting in increased TG storage in lipid droplets (LD) and upregulated expression of fibrosis markers. Hepatic stellate cells (HSCs, LX-2 cells) were co-cultured with Chang cells to assess the potential fibrogenic response to dihydroceramide, Treatment with rapamycin recovered autophagic flux in Chang cells and fibrogenesis in the co-culture system. Our results identified a critical function of dihydroceramide metabolism in autophagy. It could play an important role in the progression of NAFLD associated with lipid over-accumulation. Therefore, preventing autophagic flux by regulating dihydroceramide could be a potential strategic approach for providing therapy for NAFLD.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Ubiquitin C-terminal hydrolase-L1 plays a key role in angiogenesis by regulating hydrogen peroxide generated by NADPH oxidase 4

Ubiquitin C-terminal hydrolase-L1 (UCH-L1), which catalyzes the hydrolysis of ubiquitin esters and amides, is highly expressed in brain. Recently, UCH-L1 has been found to increase cancer cell migration and invasion by modulating hydrogen peroxide generated by NADPH oxidase 4 (NOX4). Because angiogenesis is also mediated by hydrogen peroxide, we explored the role of UCH-L1 in angiogenesis in human umbilical vein endothelial cells (HUVECs). Silencing UCH-L1 suppressed tubule formation in HUVECs, indicating that UCH-L1 promotes angiogenesis in vitro. This was confirmed using in vivo Matrigel plug studies of HUVECs, after overexpressing or silencing UCH-L1. Silencing UCH-L1 significantly suppressed VEGF-induced ROS levels as well as activation of VEGFR, both of which are required for angiogenesis. This study also showed that UCH-L1 promotes angiogenesis of HUVECs, as well as invasion in cancer cells, by up-regulating ROS by deubiquitination of NOX4, suggesting that UCH-L1 plays a key role in angiogenesis of HUVECS by regulating ROS levels by deubiquitination of NOX4.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Crystal structure of p-nitrophenol 4-monooxygenase PnpA from Pseudomonas putida DLL-E4: The key enzyme involved in p-nitrophenol degradation

Highlights: • This is the first structure of PnpA determined by X-ray crystallography. • Structure of PnpA is similar to Class A flavoprotein monooxygenases. • The substrate of PnpA is coordinated by cysteine and arginine, which is different from other PHBH family enzymes. p-Nitrophenol 4-monooxygenase PnpA, the key enzyme in the hydroquinone pathway of p-nitrophenol (PNP) degradation, catalyzes the monooxygenase reaction of PNP to p-benzoquinone in the presence of FAD and NADH. Here, we determined the first crystal structure of PnpA from Pseudomonas putida DLL-E4 in its apo and FAD-complex forms to a resolution of 2.04 Å and 2.48 Å, respectively. The PnpA structure shares a common fold with hydroxybenzoate hydroxylases, despite a low amino sequence identity of 14–18%, confirming it to be a member of the Class A flavoprotein monooxygenases. However, substrate docking studies of PnpA indicated that the residues stabilizing the substrate in an orientation suitable for catalysis are not observed in other homologous hydroxybenzoate hydroxylases, suggesting PnpA employs a unique catalytic mechanism. This work expands our understanding on the reaction mode for this enzyme class.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2013

Evaporation — a key mechanism for the thaumasite form of sulfate attack

Understanding the mechanisms leading to chemical attack on concrete is crucial in order to prevent damage of concrete structures. To date, most studies on sulfate attack and thaumasite formation are based on empirical approaches, as the identification of associated reaction mechanisms and paths is known to be highly complex. In this study, sulfate damaged concrete from Austrian tunnels was investigated by mineralogical, chemical and isotope methods to identify the reactions which caused intense concrete alteration. Major, minor and trace elemental contents as well as isotope ratios of local ground water (GW), drainage water (DW) and interstitial solutions (IS), extracted from damaged concrete material, were analyzed. Locally occurring GW contained 3 to 545 mg L{sup −1} of SO{sub 4} and is thus regarded as slightly aggressive to concrete in accordance to standard specifications (e.g. DIN EN 206-1). The concrete linings and drainage systems of the studied tunnels, however, have partly suffered from intensive sulfate attack. Heavily damaged concrete consisted mainly of thaumasite, secondary calcite, gypsum, and relicts of aggregates. Surprisingly, the concentrations of dissolved ions were extremely enriched in the IS with up to 30,000 and 12,000 mg L{sup −1} of SO{sub 4} and Cl, respectively. Analyses of aqueous ions with a highly conservative behavior, e.g. K, Rb and Li, as well as {sup 2}H/H and {sup 18}O/{sup 16}O isotope ratios of H{sub 2}O of the IS showed an intensive accumulation of ions and discrimination of the light isotopes vs. the GW. These isotope signals of the IS clearly revealed evaporation at distinct relative humidities. From ion accumulation and isotope fractionation individual total and current evaporation degrees were estimated. Our combined elemental and isotopic approach verified wetting–drying cycles within a highly dynamic concrete-solution-atmosphere system. Based on these boundary conditions, key factors controlling thaumasite formation are discussed regarding the development of more sulfate-resistant concrete and concrete structures.

36 MATERIALS SCIENCE↗
DOE OSTI2024

The intrinsic mechanical properties of hydromagnesite, Mg 5 (CO 3 ) 4 (OH) 2 ·4H 2 O, a key phase of reactive MgO carbonate cement

To potentially enable CO 2 sequestration, reactive MgO carbonate cement is emerging as an alternative binder to Portland cement. Understanding the mechanical properties of its binding phase is critical for understanding the strength development and performing materials design for reactive MgO cement systems; however, the intrinsic mechanical properties of hydromagnesite (Mg 5 (CO 3 ) 4 (OH) 2 ·4H 2 O), a key binding phase, remain unexplored. Here the present study utilized synchrotron-based high-pressure X-ray diffraction to determine the unit cell-scale, intrinsic mechanical properties of hydromagnesite for the first time. Up to hydrostatic loading of 7.7 GPa, the bulk modulus of hydromagnesite was determined as 59 GPa or 71 GPa fitted using the second-order or third-order Birch-Murnaghan equation of state, which we contextualize with binding phases in various cement systems. The experiment results are applicable in materials design of low-carbon concrete and valuable for the validation and calibration of atomistic models.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Quantification of key long-term risks at CO₂ sequestration sites: Latest results from US DOE's National Risk Assessment Partnership (NRAP) Project

Risk assessment for geologic CO₂ storage including quantification of risks is an area of active investigation. The National Risk Assessment Partnership (NRAP) is a US-Department of Energy (US-DOE) effort focused on developing a defensible, science-based methodology and platform for quantifying risk profiles at geologic CO₂ sequestration sites. NRAP has been developing a methodology that centers round development of an integrated assessment model (IAM) using system modeling approach to quantify risks and risk profiles. The IAM has been used to calculate risk profiles with a few key potential impacts due to potential CO₂ and brine leakage. The simulation results are also used to determine long-term storage security relationships and compare the long-term storage effectiveness to IPCC storage permanence goal. Additionally, we also demonstrate application of IAM for uncertainty quantification in order to determine parameters to which the uncertainty in model results is most sensitive.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Baseline projections for Latin America: base-year assumptions, key drivers and greenhouse emissions

This article provides an overview of the base-year assumptions and core baseline projections for the set of models participating in the LAMP and CLIMACAP projects. Here we present the range in core baseline projections for Latin America, and identify key differences between model projections including how these projections compare to historic trends. We find relatively large differences across models in base year assumptions related to population, GDP, energy and CO 2 emissions due to the use of different data sources, but also conclude that this does not influence the range of projections. We find that population and GDP projections across models span a broad range, comparable to the range represented by the set of Shared Socioeconomic Pathways (SSPs). Kaya-factor decomposition indicates that the set of core baseline scenarios mirrors trends experienced over the past decades. Emissions in Latin America are projected to rise as result of GDP and population growth and a minor shift in the energy mix toward fossil fuels. Most scenarios assume a somewhat higher GDP growth than historically observed and continued decline of population growth. Minor changes in energy intensity or energy mix are projected over the next few decades.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Optimization of key energy and performance metrics for drug product manufacturing

During the development of pharmaceutical manufacturing processes, detailed systems-based analysis and optimization are required to control and regulate critical quality attributes within specific ranges, to maintain product performance. As discussions on carbon footprint, sustainability, and energy efficiency are gaining prominence, the development and utilization of these concepts in pharmaceutical manufacturing are seldom reported, which limits the potential of pharmaceutical industry in maximizing key energy and performance metrics. Based on an integrated modeling and techno-economic analysis framework previously developed by the authors, this study presents the development of a combined sensitivity analysis and optimization approach to minimize energy consumption while maintaining product quality and meeting operational constraints in a pharmaceutical process. The optimal input process conditions identified were validated against experiments and good agreement resulted between simulated and experimental data. Here, the results also allowed for a comparison of the capital and operational costs for batch and continuous manufacturing schemes under nominal and optimized conditions. Using the nominal batch operations as a basis, the optimized batch operation results in a 71.7% reduction of energy consumption, whereas the optimized continuous case results in an energy saving of 83.3%.

59 BASIC BIOLOGICAL SCIENCES↗