SEARCH · Engineering Papers
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.
A system for combined heat and electric power generation, preferably including a heat reservoir and one or more electric generators, each preferably including a heat source and an energy converter. A method for combined heat and electric power generation, preferably including activating an electric generator, deactivating the electric generator, and/or providing heat from a heat reservoir.
This article investigates the intricate dynamics between Distributed Energy Resources (DERs) and the Microgrid Operator (MGO) within a microgrid interconnected with the main grid. Employing an evolutionary game framework, the study scrutinizes the strategic evolution of DERs’ decision-making processes in their interactions with the MGO. Modeled as an evolutionary game, these interactions encapsulate the strategies adopted by DERs, resulting in stable equilibrium strategies over time. Motivated by direct benefits linked to increased active power production, DERs strive to sell all available power, while the MGO focuses on optimizing the microgrid’s overall performance. The study assesses the microgrid’s performance in terms of its power factor, emphasizing the strategic balance DERs must achieve in their active power generation to avoid penalization. This penalization results in decreased individual utility for DERs due to the overall power factor decrease resulting from their prioritization of active power generation. Additionally, the diminished overall power factor implies a decrease in MGO utility. The individual utility of each DER is further influenced by the strategies adopted by other DERs, impacting the penalization factor. Leveraging a modified IEEE 13-node distribution microgrid consisting of three DERs, the study presents case studies encompassing both cooperative and non-cooperative evolutionary game scenarios. These case studies illuminate the intricacies of interactions and the resulting equilibrium outcomes.
Algae from marine and extreme environments may provide novel compounds with antiviral activity for use in therapeutic drug development. We established a first effort combining experience and cultures used in biofuel research and from the Culture Collection of Microbes from Extreme Environments at PNNL. We generated a novel library of fractionated, algae-derived compounds for guiding research on small molecules in the environment and for the treatment of SARS-CoV-2 and other infectious diseases.
We develop a hydrodynamic description of self-generated electrolyte flow in capillaries whose bounding walls feature nonuniform distributions of charge nonuniform active ionic fluxes. The hydrodynamic velocity arising in such a system has components that are forbidden by symmetry in the absence of charge and fluxes. However, when these two boundary mechanisms are simultaneously present, they can lead to a symmetry broken state where steady flows with both unidirectional and circulatory components emerge. We show that these flow states arise when modulated boundary patterns of charge and fluxes are offset by a flux-charge phase difference, which is associated with the separation between sites of their peak densities on the wall. Mismatch in diffusivity of cationic and anionic species can modify the flow states and becomes an enhancing factor when fluxes of both ion species are being produced together at the same site. We demonstrate that this mechanism can be realized with a microfluidic generator that is powered by enzyme-coated patches that catalyze reactants in the solution to produce fluxes of ions. The local ionic elevation or depletion, which disrupts a nonuniform double layer, promotes self-induced gradients yielding persistent body forces to generate bulk fluid motion. Our work quantifies a boundary-driven mechanism behind self-sustained electrolyte flow in confined environments that exists without any external bulk-imposed fields or gradients. It provides a theoretical framework for understanding the combined effect of active and charged boundaries that are relevant in biological or soft matter systems, and can be utilized in electrofluidic and iontronic applications.
All possible natural amino acids have been substituted for the native LeuL185 positioned near the B-side bacteriopheophytin (H B ) in the bacterial reaction center (RC) from Rhodobacter sphaeroides. Additional mutations are present that enhance electron transfer to the normally inactive B-side cofactors. About half the isolated RCs with Glu at L185 contain a magnesium chlorin (C B ) in place of H B . The chlorin is not the common BChl a oxidation product 3-desvinyl-3-acetyl chlorophyll a with a C-C bond in ring D and a C=C bond in ring B, but has properties consistent with reversal of these bond orders, giving 17,18-didehydro BChl a. In such RCs, charge-separated state P + C B – forms with ~5% yield. The other half of the GluL185-containing RCs have a bacteriochlorophyll a (BChl a) denoted β B in place of H B . Residues His, Asp, Asn and Gln at L185 yield RCs with ≥85% β B in the H B site, while most other amino acids result in RCs that retain H B (≥95%). To our knowledge, neither bacterial RCs that harbor five BChl a and one chlorophyll analog nor ones with six BChl a have been reported previously. The finding that altering the local environment within a cofactor binding site of a transmembrane complex leads to in situ generation of a photoactive chlorin with an unusual ring oxidation pattern suggests new strategies for amino-acid control over pigment type at specific sites in photosynthetic proteins.
Not Available
Explore the source record for details and available documents.
This study assessed two potential techniques for the extraction of pure Mo-100 target material from Mo-99/Tc-99m waste streams: 1) an established solvent-extraction method tailored for Mo-99 spent solution recycling, and 2) a low-temperature molten salt electrochemical process. By making minor modifications to the conventional solvent extraction method, particularly to accommodate the altered solubility limits arising from elevated Na+ concentrations in the waste, we achieved quantitative Mo recoveries. Although the electrochemical technique offers advantages in scalability and processing simplicity, it proved ineffective in recovering Mo from a NaOH-KOH salt melt.
Enzymes are powerful and sustainable catalysts, but their widespread application is limited by the difficulty of identifying functional starting points for optimization, creating a major bottleneck in early- stage biocatalyst discovery. Designing libraries of such starting enzymes remains particularly challenging. Here, we use the GenSLM protein language model to generate novel β-subunit of tryptophan synthase (TrpB) enzymes that express in Escherichia coli and are both stable and catalytically active. Many generated TrpBs also display significant substrate promiscuity, outperforming their natural counterparts on non-native substrates. Some even surpass laboratory-evolved TrpBs. Comparison of the most-active and most-promiscuous generated TrpB to its closest natural homolog confirms that the enhanced versatility is absent from the natural enzyme, highlighting the creative potential of generative models. These results demonstrate that the generated TrpBs not only preserve natural structure and function but also acquire non-natural properties, establishing generative models as powerful tools for biocatalyst discovery and engineering.
A database of thermally activated delayed fluorescent (TADF) molecules was automatically generated from the scientific literature. It consists of 25,482 data records with an overall precision of 82%. Among these, 5,349 records have chemical names in the form of SMILES strings which are represented with 91% accuracy; these are grouped in a subsidiary database. Each data record contains one of the following four properties: maximum emission wavelength (λ EM ), photoluminescence quantum yield (PLQY), singlet-triplet energy splitting (ΔE ST ), and delayed lifetime (τ D ). The databases were created through text mining using ChemDataExtractor, a chemistry-aware natural-language-processing toolkit, which has been adapted for TADF research. The text-mined corpus consisted of 2,733 papers from the Royal Society of Chemistry and Elsevier. To the best of our knowledge, these databases are the first databases that have been auto-generated for TADF molecules from existing publications. The databases have been publicly released for experimental and computational applications in the TADF research field.
Heterogeneous olefin metathesis catalysts exhibit low active site densities and unpredictable kinetics due to dynamic active site formation and decay processes. Here, in this study, we establish a quantitative framework that captures active site generation, renewal, and decay in olefin metathesis over silica-supported molybdenum oxide catalysts, enabling a mechanistic explanation of catalytic behavior and strategies to achieve high, stable activity. Steady-state active site titrations reveal that 2,3-dimethyl-butene isomers (4MEs) cofeeding increases active site density by up to 4.3-fold, directly correlating with enhanced metathesis rates. Spectroscopic studies demonstrate that 4MEs facilitate Mo(VI) reduction to Mo(IV) and interact strongly with surface Si–OH groups, generating labile protons that promote active site formation via a 1,2-proton shift mechanism. Kinetic modeling indicates that ethylene acts as a decay promoter, shifting kinetic control away from the Chauvin cycle and suppressing metathesis activity. Comparative studies on catalysts with varying Mo loading reveal that promotion is most effective for dispersed molybdate species, with a decline at higher Mo loadings. These findings provide a unified mechanistic framework for heterogeneous olefin metathesis, offering new strategies to enhance active site accessibility, mitigate deactivation, and optimize catalyst design.
The Waste Isolation Pilot Plant (WIPP) Land Withdrawal Act (LWA) as amended by the National Defense Authorization Act for Fiscal Year 1997 (1) requires that for Transuranic (TRU) waste to be eligible for disposal at WIPP, it must have been generated by atomic energy defense activities. The definition of “atomic energy defense activity” is defined in the Nuclear Waste Policy Act of 1982 (NWPA) (2).
Tidal stream turbines deployed at highly energetic open water sites are subjected to sheared inflow in the rotor plane. The inflow shear is expected to cause asymmetric loading on the rotor blades and affect the downstream wake. In the current study, two different turbulent inflow conditions, static-high shear and dynamic shear, were generated via an active-grid turbulence generator. A 1:20 scaled three-bladed horizontal axis tidal turbine model was tested in those conditions. The results were compared to a quasi-laminar case with no imposed turbulence or shear. The results show that the high shear reduces the average performance, with a drop of up to 16% in the optimal power coefficient. Besides, the shear profiles increase torque fluctuations and induce significant differences in wake hydrodynamics between the high-speed (upper) and low-speed (lower) regions. The large integral length scales further enhance the load fluctuations perceived by the rotor but have a negligible effect on the mean wake field quantities and the wake recovery. The lower half region featured a faster breakdown of tip vortex structure and a rapid drop of swirl number, a phenomenon conjectured to be a consequence of the strong turbulence intensities and Reynolds stresses in the lower half region. Furthermore, the sheared turbulent inflow also results in a very intensive energy redistribution process towards large-scale, low-frequency motions, which is important to the downstream turbines.
Active materials are characterized by continuous injection of energy at the microscopic level and typically cannot be adequately described by equilibrium thermodynamics. Here we study a class of active fluids in which equilibrium-like properties emerge when fluctuating and activated degrees of freedom are statistically decoupled, such that their mutual information is negligible. We analyse three paradigmatic systems: chiral active fluids composed of spinning frictional particles that are free to translate, oscillating granular gases and active Brownian rollers. In all of these systems, a single effective temperature generated by activity parameterizes both the equation of state and the emergent Boltzmann statistics. The same effective temperature, renormalized by velocity correlations, relates viscosities to steady-state stress fluctuations via a Green–Kubo relation. To rationalize these observations, we develop a theory for the fluctuating hydrodynamics of these non-equilibrium fluids and validate it through large-scale molecular dynamics simulations. Our work sheds light on the microscopic origin of odd viscosities and stress fluctuations characteristic of parity-violating fluids, in which mirror symmetry and detailed balance are broken.
Atomic hydrogen (H) generated by atmospheric pressure radio frequency (RF) plasma jet is investigated by two-photon absorption laser induced fluorescence in a He-H 2 mixture. The reported time and spatially resolved H density profiles enable a detailed analysis of the species generation, transport and decay along the axis of symmetry of the jet. Here, the H density distribution for a continuous RF plasma jet corresponds well with the outcome of a Pseudo-1D plug flow model. In addition, RF power modulation has a strong effect on the H density in the active discharge region but has a negligible effect on the H density in the far effluent.
Organic intercalation of layered nanomaterials is an attractive strategy to fabricate organic/inorganic superlattices for a wide range of promising applications. However, the synthesis of 2D organic/inorganic superlattice nanosheets remains a big challenge. In this work, the preparation of 2D polyaniline/MoO 3–x (PANI/MoO 3–x ) superlattice nanosheets via intercalation-induced morphological transformation from MoO 3 nanobelts, as efficient Fenton-like reagents for chemodynamic therapy (CDT), is reported. Micrometer-long MoO 3 nanobelts are co-intercalated with Na + /H 2 O followed by the guest exchange with aniline monomer for in situ polymerization to obtain PANI/MoO 3–x nanosheets. Intriguingly, the PANI intercalation can induce the morphological transformation from long MoO 3 nanobelts to 2D PANI/MoO 3–x nanosheets along with the partial reduction of Mo 6+ to Mo 5+ , and generation of rich oxygen vacancies. More importantly, thanks to the PANI intercalation-induced activation, the PANI/MoO 3–x nanosheets exhibit excellent Fenton-like catalytic activity for generation of hydroxyl radical (·OH) by decomposing H 2 O 2 compared with the MoO 3 nanobelts. It is speculated that the good conductivity of PANI can facilitate electron transport during the Fenton-like reaction, thereby enhancing the efficiency of CDT. Thus, the polyvinylpyrrolidone-modified PANI/MoO 3–x nanosheets can function as Fenton-like reagents for highly efficient CDT to kill cancer cells and eradicate tumors.
Techniques are described for disaggregation of renewable energy generation on an electricity distribution system. Aggregate power measurements are identified a distribution substation. Active power load of the distribution substation and active power generated by renewable energy sites can be disaggregated from the aggregate power measurements.
Electrocatalysts that start a reaction as molecules do not always end the reaction as molecules, and even when they do, they might not be molecules during catalysis. In this Perspective, we discuss knowledge learned from the study of Cu-based molecularly structured electrocatalysts––including metal coordination complexes, metal-organic frameworks, single-atom catalysts, and polymeric materials––that restructure under electrochemical CO 2 reduction reactions. Recent reports are summarized with an emphasis on the nature and significance of post-mortem and in situ characterization for the proper identification of active sites. We demonstrate that molecular and material structures determine whether electrocatalysts restructure and how they restructure, that understanding of restructuring processes can help us identify active sites for catalysis, and that this knowledge can be leveraged to design precatalysts that generate highly active catalysts under reaction conditions. In addition, we provide recommended practices for studying the integrity of heterogeneous molecular catalysts during and after CO 2 reduction reactions.