SEARCH · Search NASA
Results for “FACTORIZATION”
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.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
Manipulation of Ni Interstitials for Realizing Large Power Factor in TiNiSn-Based Materials
Not provided.
The role of nuclear factor E2-Related factor 2 and uncoupling protein 2 in glutathione metabolism: Evidence from an in vivo gene knockout study
Nuclear factor E2-related factor 2 (NRF2) and uncoupling protein 2 (UCP2) are indicated to protect from oxidative stress. They also play roles in the homeostasis of glutathione. However, the detailed mechanisms are not well understood. In the present study, we found Nrf2-knockout (Nrf2-KO) mice exhibited altered glutathione homeostasis and reduced expression of various genes involved in GSH biosynthesis, regeneration, utilization and transport in the liver. Ucp2-knockout (Ucp2-KO) mice exhibited altered glutathione homeostasis in the liver, spleen and blood, as well as increased transcript of cystic fibrosis transmembrane conductance regulator in the liver, a protein capable of mediating glutathione efflux. Nrf2-Ucp2-double knockout (DKO) mice showed characteristics of both Nrf2-KO and Ucp2-KO mice. But no significant difference was observed in DKO mice when compared with Nrf2-KO or Ucp2-KO mice, except in blood glutathione levels. These data suggest that ablation of Nrf2 and Ucp2 leads to disrupted GSH balance, which could result from altered expression of genes involved in GSH metabolism. DKO may not evoke more severe oxidative stress than the single gene knockout. - Highlights: • Nrf2/Ucp2 deficiency leads to alteration of glutathione homeostasis. • Nrf2 regulates expression of genes in glutathione generation and utilization. • Ucp2 affects glutathione metabolism by regulating hepatic efflux of glutathione. • Nrf2 deficiency may not aggravate oxidative stress in Ucp2-deficient mice.
Monte Carlo calculation and verification of the geometrical factors for the NPDGamma experiment
The NPDGamma experiment measures the parity-violating asymmetry in gamma-ray emission in the capture of polarized neutrons on liquid parahydrogen. The sensitivity to the asymmetry for each detector in the array is used as a parameter in the extraction of the physics asymmetry from the measured data. The detector array is approximately cylindrically symmetric around the target and a step-wise sinusoidal function has been used for the sensitivity in the previous iteration of the NPDGamma experiment, but deviations from cylindrical symmetry necessitate the use of a Monte Carlo model to determine corrections to the geometrical factors. For the calculations, source code modifications to MCNPX were done in order to calculate the sensitivity of each cesium iodide detector to the physics asymmetry. We describe the MCNPX model and results from calculations and how the results are validated through measurement of the parity violating asymmetry of gamma-rays from neutron capture on chlorine.
Salinity-Induced Reduction of Interfacial Energies and Kinetic Factors during Calcium Carbonate Nucleation on Quartz
Abstract not provided
Inhibitor Mimetic Mutations in the Pseudomonas aeruginosa PqsE Enzyme Reveal a Protein-Protein Interaction with the Quorum-Sensing Receptor RhlR That Is Vital for Virulence Factor Production
Explore the source record for details and available documents.
Supramolecular Motion Enables Chondrogenic Bioactivity of a Cyclic Peptide Mimetic of Transforming Growth Factor-β1
Transforming growth factor (TGF)-β1 is a multifunctional protein that is essential in many cellular processes that include fibrosis, inflammation, chondrogenesis, and cartilage repair. In particular, cartilage repair is important to avoid physical disability since this tissue does not have the inherent capacity to regenerate beyond full development. We report here on supramolecular coassemblies of two peptide amphiphile molecules, one containing a TGF-β1 mimetic peptide, and another which is one of two constitutional isomers lacking bioactivity. Using human articular chondrocytes, we investigated the bioactivity of the supramolecular copolymers of each isomer displaying either the previously reported linear form of the mimetic peptide or a novel cyclic analogue. Based on fluorescence depolarization and 1 H NMR spin–lattice relaxation times, we found that coassemblies containing the cyclic compound and the most dynamic isomer exhibited the highest intracellular TGF-β1 signaling and gene expression of cartilage extracellular matrix components. Here, we conclude that control of supramolecular motion is emerging as an important factor in the binding of synthetic molecules to receptors that can be tuned through chemical structure.
Systematic discovery of pseudomonad genetic factors involved in sensitivity to tailocins
Tailocins are bactericidal protein complexes produced by a wide variety of bacteria that kill closely related strains and may play a role in microbial community structure. Thanks to their high specificity, tailocins have been proposed as precision antibacterial agents for therapeutic applications. Compared to tailed phages, with whom they share an evolutionary and morphological relationship, bacterially produced tailocins kill their host upon production but producing strains display resistance to self-intoxication. Though lipopolysaccharide (LPS) has been shown to act as a receptor for tailocins, the breadth of factors involved in tailocin sensitivity, and the mechanisms behind resistance to self-intoxication, remain unclear. Here, we employed genome-wide screens in four non-model pseudomonads to identify mutants with altered fitness in the presence of tailocins produced by closely related pseudomonads. Our mutant screens identified O-antigen composition and display as most important in defining sensitivity to our tailocins. In addition, the screens suggest LPS thinning as a mechanism by which resistant strains can become more sensitive to tailocins. Furthermore, we validate many of these novel findings, and extend these observations of tailocin sensitivity to 130 genome-sequenced pseudomonads. This work offers insights into tailocin–bacteria interactions, informing the potential use of tailocins in microbiome manipulation and antibacterial therapy.
Important Factors for the Reliable and Reproducible Preparation of Non-aqueous Electrolyte Solutions for Lithium Batteries
Electrolyte solutions play a crucial role in rechargeable lithium batteries. Driven by an ever-increasing demand for better batteries, more and more stringent performance requirements are being asked of electrolytes. This demand to achieve electrolytes beyond the state-of-the-art has driven an increasing number of publications over the past decade. Nevertheless, a detailed description of electrolyte preparation is frequently missing when reporting new electrolytes for batteries, creating a barrier for others to reproduce important findings. In addition, false or misleading information in a paper may result from unintentional inaccuracies during the electrolyte preparation process. This article highlights important factors for the reliable and reproducible preparation of non-aqueous electrolyte solutions for lithium batteries, with the aim of encouraging researchers to follow more rigorous reporting standards.
Ni and Se co-doping increases the power factor and thermoelectric performance of CoSbS
In this paper, we present a new investigation on paracostibite (CoSbS), a potential thermoelectric material for power generation in the intermediate temperature range (700–900 K) consisting of earth abundant elements. We report an improved synthesis of single phase materials of Co 1–x Ni x SbS 1–y Se y (x = 0–0.07, y = 0–0.09) using vacuum melting and annealing followed by SPS processing. The effects of Ni and Se co-doping on the electronic and thermal transport properties of CoSbS were investigated. Doping with Ni on the Co site increases the carrier concentration and moves the Fermi level deep into the conduction band, producing an enhanced power factor. First-principles electronic band structure calculations indicate a multi valley nature of the conduction band where Ni doping leads to n-type behaviour and a sharp increase of the density of states effective mass, enhancing the Seebeck coefficient. Unlike the Ni doping which has little effect on thermal transport, alloying Se on the S site intensifies the alloying scattering resulting in a lower lattice thermal conductivity of 2.4 W m –1 K –1 at 900 K for Co 0.93 Ni 0.07 SbS 0.93 Se 0.07 . Alloying Se on the S site of the structure further boosts the power factor to 22 μW cm –1 K –2 and leads to a maximum ZT of 0.58 at 900 K, which is the best ZT value achieved in the system.
Neutrino-Nucleus Cross Section within the Extended Factorization Scheme
The factorization scheme, based on the impulse approximation and the spectral function formalism, has been recently generalized to allow the description of electromagnetic nuclear interactions driven by two-nucleon currents. We have extended this framework to the case of weakly charged and neutral currents, and carried out calculations of the double-differential neutrino-carbon and neutrino-oxygen cross sections using two different models of the target spectral functions. The results, showing a moderate dependence on the input spectral function, confirm that our approach provides a consistent treatment of all reaction mechanisms contributing to the signals detected by accelerator-based neutrino experiments.
Effective J -factor of the Galactic Center for velocity-dependent dark matter annihilation
Here, we introduce the effective J -factors for the Milky Way for scenarios in which dark matter annihilation is p -wave or d -wave suppressed. We find that the velocity suppression of dark matter annihilation can have a sizable effect on the morphology of a potential dark matter annihilation signal in the Galactic Center. The gamma-ray flux from the innermost region of the Galactic Center is in particular suppressed. We discover that for dark matter density profiles with steep inner slopes, the morphology of the inner Galaxy gamma-ray emission in p -wave models can be made similar to the morphology in standard s -wave models. This similarity may suggest that model discrimination between s wave and p wave is challenging, e.g., when fitting the Galactic Center excess. However, we show that it is difficult to simultaneously match s - and p -wave morphologies at both large and small angular scales. The J -factors we calculate may be implemented with astrophysical foreground models to self-consistently determine the morphology of the excess with velocity-suppressed dark matter annihilation.
Machine Learning of Factors Influencing Damping and Frequency of Dominant Inter-area Modes in the WECC Interconnect
The stability of inter-area electromechanical oscillations are critical to power system reliability. Due to the complexities of power systems, relationships between system conditions and oscillation characteristics, such as damping and frequency, tend to be expressed only in generalities. In this study, a list of influential factors on Western Electricity Coordinating Council (WECC) interconnect modal characteristics are identified and evaluated with advanced machine learning techniques including principal component analysis, analysis of variance, random forest feature selection, support vector machine, and artificial neural network approaches.
Default Radioactive and Hazardous Waste Management (RHWM) Dose Conversion Factors (DCFs) and Weighting Factors and plutonium-239 equivalent Curie (PE-Ci) methodology for acceptance into the Waste Storage Facilities
DOE-STD-5506-2007 (Ref. 1) is the standard that provides the methodology for preparing hazard analysis and accident analysis for transuranic (TRU) waste facilities. The Waste Storage Facilities hazard and accident analysis for the DSA is developed in accordance with DOE-STD- 5506-2007. Two related issues need to be addressed when implementing DOE-STD-5506-2007 regarding the calculation of consequences from TRU waste releases in accident analysis: Consequences determined in accident analysis must be modeled using inhalation Dose Conversion Factors (DCFs) that are consistent with those from the International Commission on Radiological Protection Publication 72 (ICRP-72, Ref. 2).; The use of a statistical Material at Risk (MAR) representing the distribution of radiological loading of TRU waste containers based on the use of a plutonium-239 equivalent Curie (PE-Ci) methodology. The PE-Ci methodology simplifies accident analysis by allowing one to model releases based on the Curie value of one standard nuclide (e.g., Pu-239) instead of needing to model releases for every potential nuclide of interest. This is accomplished by normalizing the Curie value of all nuclides to a single Curie value of a standard nuclide by using a Weighting Factor that is a ratio of the DCFs associated with the nuclides and that of the standard nuclide. By using the ICRP-72 DCFs to calculate PE-Ci values used in the statistical MAR, the accident analysis that uses that statistical MAR will be consistent with the consequence methodology identified in DOE-STD- 5506-2007.
Existing Hydropower Assets (EHA) Capacity Factor Plant Database, 2005-2024
Existing Hydropower Asset (EHA) Annual Capacity Factor is a geospatial point-level dataset containing annual capacity factors over the years (2005-2024) and key characteristics of operational U.S. hydropower plants with 1 megawatt or greater of nameplate capacity. EIA form 860 and EHA are the primary sources of the derived data. Pumped storage and hybrid plants are excluded.
Existing Hydropower Asset (EHA) Capacity Factor Plant Database (2005-2025)
Explore the source record for details and available documents.
Amphoteric Indium Enables Carrier Engineering to Enhance the Power Factor and Thermoelectric Performance in n -Type Ag n Pb 100 In n Te 100+2 n (LIST)
The Ag and In co-doped PbTe, Ag n Pb 100 In n Te 100+2n (LIST), exhibits n-type behavior and features unique inherent electronic levels that induce self-tuning carrier density. Results show that In is amphoteric in the LIST, forming both In 3+ and In 1+ centers. Through unique interplay of valence fluctuations in the In centers and conduction band filling, the electron carrier density can be increased from ≈3.1 × 10 18 cm -3 at 323 K to ≈2.4 × 10 19 cm -3 at 820 K, leading to large power factors peaking at ≈16.0 μWcm -1 K -2 at 873 K. The lone pair of electrons from In + can be thermally continuously promoted into the conduction band forming In 3+ , consistent with the amphoteric character of In. Moreover, with rising temperature, the Fermi level shifts into the conduction band, which enlarges the optical band gap based on the Moss–Burstein effect, and reduces bipolar diffusion and thermal conductivity. Adding extra Ag in LIST improves the electrical transport properties and meanwhile lowers the lattice thermal conductivity to ≈0.40 Wm -1 K -1 . Here, the addition of Ag creates spindle-shaped Ag 2 Te nanoprecipitates and atomic-scale interstitials that scatter a broader set of phonons. As a result, a maximum ZT value ≈1.5 at 873 K is achieved in Ag 6 Pb 100 InTe 102 (LIST).
EVALUATION OF HOT CHANNEL FACTOR FOR SODIUM-COOLED FAST REACTORS WITH MULTI-PHYSICS TOOLKIT
The evaluation of hot channel factor (HCF) is of great significance to the quantification of safety margins for reactor designs. In this paper, HCFs for a sodium-cooled fast reactor (SFR) are evaluated with the Simulation-based High-efficiency Advanced Reactor Prototyping (SHARP) toolkit, which is developed under the Nuclear Energy Advanced Modeling and Simulation (NEAMS) Campaign of DOE for multi-physics reactor performance and safety simulations. The high-fidelity neutronics and thermal hydraulics solvers PROTEUS and Nek5000 in the SHARP toolkit are coupled to perform the multi-physics simulations for HCF evaluation. The HCFs induced by cladding manufacturing tolerance, fissile content mal-distribution, wire orientation and uncertainties on the cladding, coolant, and fuel properties are evaluated for a reference core SFR design (AFR-100). The HCFs calculated with the SHARP toolkit are compared to legacy HCFs for similar reactor types. The comparison demonstrates the reduction or elimination of modeling uncertainties in the calculation of HCFs using high fidelity advanced modeling and simulation tools without the need of expensive experiments. Moreover, the reduction of the uncertainties on HCFs evaluation allows an increase in nominal parameters and safety margin, which in turn improves the economic competitiveness of the SFR.