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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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Systematic Evaluation of Atmospheric Forcing, Surface Datasets, and Mesh Effects on Kilometer-Scale Land Surface and River Modeling
Earth system models are advancing toward kilometer-scale resolution to capture local climate impacts and extremes. High-resolution land and river modeling depends on multiple factors, including mesh, surface datasets, and atmospheric forcing, but their relative effects at kilometer scales remain unquantified. We evaluated five Energy Exascale Earth System Model land and river configurations over the Mid-Atlantic region using two mesh (1/8° structured versus variable-resolution unstructured mesh), two surface datasets (default versus newly developed), and three atmospheric forcings (NLDAS2, MSWX, GSWP). Evaluation against satellite, reanalysis, and in situ benchmarks across water, energy, and carbon cycles quantifies how these factors affect model performance. Forcing selection produces the largest bias reductions (12-99% across variables), followed by surface datasets (7-75%) and mesh (up to 21%). Forcing effects vary by variable, with MSWX reducing biases for snow water equivalent, evapotranspiration, albedo, temperature, and gross primary productivity, GSWP for snow cover and runoff, and NLDAS for soil moisture and streamflow. The use of newly developed surface datasets improves gross primary productivity (58% bias reduction) and evapotranspiration but increase soil moisture and albedo biases due to current modeling limitations. Variable-resolution unstructured mesh improves the simulation of small-basin streamflow through better capturing drainage networks, though mesh minimally affects other land variables. These findings provide important guidance for high-resolution modeling development and actionable science.
Effects of shielding gas and spot reduction on humping suppression in high-speed laser welding
High-speed laser welding is a crucial process to enhance the production rate of fuel cell fabrication. However, exceeding a critical welding speed leads to defect formation such as humps and root concavities, which degrade weld quality and mechanical performance. This study employed shielding gas and spot reduction approaches to suppress these defects. The relationships between individual defect types and their influence on weld strength were systematically examined. Moreover, in situ high-speed synchrotron X-ray imaging was employed to comprehend the mechanisms of humping mitigation by shielding gas through analysis of instantaneous keyhole and melt pool dynamics. The observations reveal that shielding gas mitigates humping by shortening the molten pool through enhanced surface heat convection and by altering surface tension to prevent melt flow collisions. The effects of shielding gas and spot reduction were further incorporated into the dimensionless humping index (π h ) that describes the humping formation tendency. These findings provide mechanistic insights and quantitative guidance for defect control strategies in high-speed laser welding.
Structural Characterization of the Glycoprotein GP2 Core Domain from the CAS Virus, a Novel Arenavir
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Structural Characterization of Anti-Inflammatory Immunoglobulin G Fc Proteins
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Extent and Origins of Functional Diversity in a Subfamily of Glycoside Hydrolases
Some glycoside hydrolases have broad specificity for hydrolysis of glycosidic bonds, potentially increasing their functional utility and flexibility in physiological and industrial applications. Here, to deepen the understanding of the structural and evolutionary driving forces underlying specificity patterns in glycoside hydrolase family 5, we quantitatively screened the activity of the catalytic core domains from subfamily 4 (GH5_4) and closely related enzymes on four substrates: lichenan, xylan, mannan, and xyloglucan. Phylogenetic analysis revealed that GH5_4 consists of three major clades, and one of these clades, referred to here as clade 3, displayed average specific activities of 4.2 and 1.2 U/mg on lichenan and xylan, approximately 1 order of magnitude larger than the average for active enzymes in clades 1 and 2. Enzymes in clade 3 also more consistently met assay detection thresholds for reaction with all four substrates. We also identified a subfamily-wide positive correlation between lichenase and xylanase activities, as well as a weaker relationship between lichenase and xyloglucanase. To connect these results to structural features, we used the structure of CelE from Hungateiclostridium thermocellum (PDB 4IM4) as an example clade 3 enzyme with activities on all four substrates. Comparison of the sequence and structure of this enzyme with others throughout GH5_4 and neighboring subfamilies reveals at least two residues (H149 and W203) that are linked to strong activity across the substrates. Placing GH5_4 in context with other related subfamilies, we highlight several possibilities for the ongoing evolutionary specialization of GH5_4 enzymes.
Patternable, Solution-Processed Ionogels for Thin-Film Lithium-Ion Electrolytes
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Alkyl Chain Tuning of Small Molecule Acceptors for Efficient Organic Solar Cells
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Selective Hole and Electron Transport in Efficient Quaternary Blend Organic Solar Cells
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Photo-induced halide redistribution in 2D halide perovskite lateral heterostructures
An improved understanding of the degradation pathways under external stimuli is needed to address stability challenges in two-dimensional (2D) perovskite semiconductor materials. Here, in this study, in situ synchrotron nanoprobe X-ray fluorescence (nano-XRF) is used to investigate the evolution of halide redistribution within various 2D halide perovskite (n = 1–3) lateral heterostructures under ultraviolet (UV) exposure. Further, the results show that iodine (I) experiences a loss in all cases, with the rate of change following the perovskite dimensionality monotonically. In contrast, bromine (Br) is relatively more stable than I in n = 2 and 3 heterostructures, with no significant change in the total Br concentration but a visible amount of Br diffusion to the previously I-rich regime. Combining nano-XRF and X-ray absorption spectroscopy (XAS), we found a reduction of dimensionality in crystals with n > 1 after UV exposure, indicating significant structural reconfiguration beyond ion migration.
A general approach to develop reduced order models for simulation of solid oxide fuel cell stacks
A reduced order modeling approach based on response surface techniques was developed for solid oxide fuel cell stacks. This approach creates a numerical model that can quickly compute desired performance variables of interest for a stack based on its input parameter set. The approach carefully samples the multidimensional design space based on the input parameter ranges, evaluates a detailed stack model at each of the sampled points, and performs regression for selected performance variables of interest to determine the responsive surfaces. After error analysis to ensure that sufficient accuracy is established for the response surfaces, they are then implemented in a calculator module for system-level studies. The benefit of this modeling approach is that it is sufficiently fast for integration with system modeling software and simulation of fuel cell-based power systems while still providing high fidelity information about the internal distributions of key variables. This paper describes the sampling, regression, sensitivity, error, and principal component analyses to identify the applicable methods for simulating a planar fuel cell stack.
Hydrothermal synthesis of LiMn2O4 onto carbon fiber paper current collector for binder free lithium-ion battery positive electrodes
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A durable polyvinyl butyral-CsH 2 PO 4 composite electrolyte for solid acid fuel cells
We report a composite electrolyte membrane composed of polyvinyl butyral (PVB) and CsH 2 PO 4 has been prepared via a facile and cost-effective method for solid acid fuel cells. The effect of PVB content on conductivity, mechanical integrity, and fuel cell performance is investigated. A minimum amount of 3 wt% PVB in the CsH 2 PO 4 -based composite electrolyte not only offers the required mechanical integrity but also allows high conductivity (~28 mS cm -1 at 260 °C). Single cells based on the composite electrolytes demonstrate a peak power density of 108 mW cm -2 at 260 °C. Almost no degradation in electrochemical performance could be observed during the stability test for 10 h and three thermal-cycling test in H 2 /O 2 fuel cell, indicating the promising application of the composite electrolyte in solid acid fuel cells.
New high-pressure polymorph of In{sub 2}S{sub 3} with defect Th{sub 3}P{sub 4}-type structure
The high pressure behavior of β-In{sub 2}S{sub 3} (I4{sub 1}/amd and Z=16) has been studied by in situ synchrotron radiation X-ray diffraction combined with diamond anvil cell up to 71.7 GPa. Three pressure-induced phase transitions are evidenced at ∼6.6 GPa, ∼11.1 GPa at room temperature and 35.6 GPa after the high-temperature annealing using a portable laser heating system. The new polymorph of In{sub 2}S{sub 3} at 35.6 GPa is assigned to the denser cubic defect Th{sub 3}P{sub 4} structure (I4¯3d and Z=5.333), whose unit-cell parameters are a=7.557(1) Å and V=431.6(2) Å{sup 3}. The Th{sub 3}P{sub 4}-type phase can be stable at least up to 71.7 GPa and cannot be preserved at ambient pressure. The pressure–volume relationship is well described by the second-order Birch–Murnaghan Equation of State, which yields B{sub 0}=63(3) GPa and B{sub 0}′=4 (fixed) for the β-In{sub 2}S{sub 3} phase and B{sub 0}=87(3) GPa and B{sub 0}′=4 (fixed) for the defect Th{sub 3}P{sub 4}-type phase respectively. - Graphical abstract: The structure and Rietveld refinement of new polymorph the defect Th{sub 3}P{sub 4}-type In{sub 2}S{sub 3}. This structure was observed at 35.6 GPa after laser heating by X-ray diffraction. Display Omitted - Highlights: Three pressure-induced phase transitions of β-In{sub 2}S{sub 3} were observed. β-In{sub 2}S{sub 3} was stable up to 6.6 GPa. The defect Th{sub 3}P{sub 4}-type In{sub 2}S{sub 3} was identified at 35.6 GPa after laser heating and was stable up to 71.7 GPa. Elastic properties of β-In{sub 2}S{sub 3} and Th{sub 3}P{sub 4}-type In{sub 2}S{sub 3} are well presented by Birch–Murnaghan EoS.
Cd(II) complexes with different nuclearity and dimensionality based on 3-hydrazino-4-amino-1,2,4-triazole
A series of zero- to two-dimensional Cd(II) coordination compounds have been synthesized by the reaction of Cd(II) salts and 3-hydrazino-4-amino-1,2,4-triazole di-hydrochloride (HATr·2HCl). [CdCl{sub 2}(HATr){sub 2}] (1) and [Cd{sub 2}Cl{sub 4}(HATr){sub 2}(H{sub 2}O){sub 2}] (2) have discrete mononuclear and binuclear structures, respectively. [Cd(HATr){sub 2}(ClO{sub 4}){sub 2}]{sub n} (3) presents polymeric 1-D chain and [Cd{sub 2}(NO{sub 3}){sub 2}Cl{sub 2}(HATr){sub 2}]{sub n} (4) shows 2-D frameworks. All Cd(II) ions exhibit distorted octahedral configurations in 1–3, whilst both hexa and heptacoordinated Cd(II) are formed in 4. The HATr ligands adopt chelating coordinated mode in 1, while tri-dentate bridging–chelating mode in 2–4. The chloride ion is a mono-coordinated ligand in 1 and 2, but it bridges two adjacent metal ions in 4. Furthermore, thermal behaviors have been investigated and the results reveal that all complexes have good thermal stability. The impact sensitivity test indicates that complex 3 is sensitive to impact stimuli. - Graphical abstract: Four Cd(II) complexes based on 3-hydrazino-4-amino-1,2,4-triazole ligands exhibit diverse structures from mononuclear to 2D networks. - Highlights: • Cd(II) complexes containing 3-hydrazino-4-amino-1,2,4-triazole ligands. • Mononuclear, binuclear, 1-D and 2-D structures. • Good thermal stability. • Thermal decomposition kinetics.