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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 1,639 records · Page 91
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

The solvent component of macromolecular crystals

On average, the mother liquor or solvent and its constituents occupy about 50% of a macromolecular crystal. Ordered as well as disordered solvent components need to be accurately accounted for in modelling and refinement, often with considerable complexity. The mother liquor from which a biomolecular crystal is grown will contain water, buffer molecules, native ligands and cofactors, crystallization precipitants and additives, various metal ions, and often small-molecule ligands or inhibitors. On average, about half the volume of a biomolecular crystal consists of this mother liquor, whose components form the disordered bulk solvent. Its scattering contributions can be exploited in initial phasing and must be included in crystal structure refinement as a bulk-solvent model. Concomitantly, distinct electron density originating from ordered solvent components must be correctly identified and represented as part of the atomic crystal structure model. Herein, are reviewed (i) probabilistic bulk-solvent content estimates, (ii) the use of bulk-solvent density modification in phase improvement, (iii) bulk-solvent models and refinement of bulk-solvent contributions and (iv) modelling and validation of ordered solvent constituents. A brief summary is provided of current tools for bulk-solvent analysis and refinement, as well as of modelling, refinement and analysis of ordered solvent components, including small-molecule ligands.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2024

Nonlinear elasticity with the Shifted Boundary Method

Here, we propose a new unfitted/immersed computational framework for nonlinear solid mechanics, which bypasses the complexities associated with the generation of CAD representations and subsequent body-fitted meshing. This approach allows to speed up the cycle of design and analysis in complex geometry and requires relatively simple computer graphics representations of the surface geometries to be simulated, such as the Standard Tessellation Language (STL format). Complex data structures and integration on cut elements are avoided by means of an approximate boundary representation and a modification (shifting) of the boundary conditions to maintain optimal accuracy. An extensive set of computational experiments in two and three dimensions is included.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

The developments in modifying functionality of lignin and its application in biocomposites

With the advancement of sustainable material innovations, renewable natural biopolymers are gradually replacing traditional metal and petroleum-based synthetic materials due to their environmental friendliness, biodegradability, and economic advantages. Lignin, the second most abundant natural aromatic polymer in the plant kingdom, has emerged as a key candidate raw material for the development of green polymer systems because of its unique phenylpropane unit network structure, high carbon content, and rich functional group characteristics. However, challenges such as the inherent structural complexity, chemical inertness, and uneven molecular weight distribution of lignin limit its direct application. By employing modification strategies such as chemical functionalization and physical regulation, researchers can precisely control its reactivity, thermal stability, and interfacial compatibility, enabling the preparation of high-performance lignin-based functional composites. Here, this paper systematically reviews the principles and methodological advancements in lignin's multi-dimensional modification technology. It analyzes the mechanisms by which various chemical and physical modification techniques enhance the mechanical properties, functional responsiveness, and environmental adaptability of materials, and discusses innovative applications in fields such as intelligent packaging, biomedical materials, and energy storage devices. Furthermore, this review addresses the key challenges encountered in the high-value transformation of lignin, with the aim of offering a theoretical framework and technical pathway for the transformative development of lignin from agricultural and forestry by-products to functional material platforms.

Functional composites↗
DOE OSTI2019

Molecular Recognition of M1-Linked Ubiquitin Chains by Native and Phosphorylated UBAN Domains

Ub-binding domain in ABIN proteins and NEMO (UBAN) is highly conserved, yet UBAN-containing proteins exhibit different Ub-binding properties, resulting in their diverse biological roles. Post-translational modifications further control UBAN domain specificity for poly-Ub chains. However, precisely, how the UBAN domain structurally confers such functional diversity remains poorly understood. Here we report crystal structures of ABIN-1 alone and in complex with one or two M1-linked di-Ub chains. ABIN-1 UBAN forms a homo-dimer that provides two symmetrical Ub-binding sites on either side of the coiled-coil structure. Moreover, crystal structures of ABIN1 UBAN in complex with di-Ub chains reveal a concentration-dependency of UBAN/di-Ub binding stoichiometry. Analysis of UBAN/M1-linked di-Ub binding characteristics indicates that phosphorylated S473 in OPTN and its corresponding phospho-mimetic residue in ABIN-1 (E484) are essential for high affinity interactions with M1-linked Ub chains. Also, a phospho-mimetic mutation of A303 in NEMO, corresponding to S473 of OPTN, increases binding affinity for M1-linked Ub chains. These findings are in line with the diverse physiological roles of UBAN domains, as phosphorylation of OPTN UBAN is required to enhance its binding to Ub during mitophagy.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2021

Nanostructured Block Polymer Electrolytes: Tailoring Self-Assembly to Unlock the Potential in Lithium-Ion Batteries

Ion-containing solid block polymer (BP) electrolytes can self-assemble into microphase-separated domains to facilitate the independent optimization of ion conduction and mechanical stability; this assembly behavior has the potential to improve the functionality and safety of lithium-ion batteries over liquid electrolytes to meet future demands (e.g., large capacities and long lifetimes) in various applications. However, significant enhancements in the ionic conductivity and processability of BPs must be realized for BP-based electrolytes to become robust alternatives in commercial devices. Toward this end, the controlled modification of BP electrolytes’ intra-domain (nanometer-scale) and multi-grain (micrometer-scale) structure is one viable approach; intra-domain ion transport and segmental compatibility (related to the effective Flory–Huggins parameter, χ eff ) can be increased by tuning the ion and monomer-segment distributions, and the morphology can be selected such that the multi-grain transport is less sensitive to grain size and orientation.

25 ENERGY STORAGE↗
DOE OSTI2018

Li-Substituted Layered-Spinel Cathode Material for Sodium-Ion Batteries

The O 3 -type layered Na(Ni x Fe y Mn z )O 2 (0 < x, y, z < 1) cathode materials have attracted great interest in sodium ion batteries due to the abundance and cost of raw materials and their high specific capacities. However, the cycling stability and rate capability at high voltages (> 4.0 V) of these materials remain an issue. In this work, we successfully synthesized a Li-substituted layered-tunneled (O 3 -spinel) intergrowth cathode (LS-NFM) to address these issues. The remarkable structural compatibility and connectivity of the two phases were confirmed by X-ray diffraction (XRD), selected area electron diffraction (SAED), and high-resolution transmission electron microscopy (HRTEM). The LS-NFM electrode reached a discharge capacity of 96 mAh g -1 with a capacity retention of 86% after 100 cycles at a current rate of 100 mA g -1 in a voltage window of 2.0-4.2 V. Moreover, the LS-NFM cathode exhibited an enhanced rate capability in comparison to the undoped single-phased layered cathode (NFM). The enhanced rate capability of LS-NFM can be explained by the significantly increased effective Na + diffusivity measured by the galvanostatic intermittent titration technique (GITT) compared to the undoped control NFM cathode, which can be ascribed to the improved charge transport kinetics through shortened diffusion path by direct connection between the 3D channels in the spinel phase and 2D channels in the layered phase. The results from ex situ hard/soft X-ray adsorption spectroscopy (XAS) suggest that the capacity of the LS-NFM cathode is mainly associated with the Ni 2+ /Ni 4+ redox couple and slightly from the Fe 3+ /Fe 4+ redox couple. The voltage profile of the LS-NFM cathode exhibits a reversible plateau above 4.0 V, indicating great stability at high voltages and structural stabilization by the spinel phase. In addition to the substitution of various transition metals, or the modification of the stoichiometry of each transition metal, this study provides a new strategy to improve electrochemical performance of layered cathode materials for sodium ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

phosaa14SB and phosaa19SB: Updated Amber Force Field Parameters for Phosphorylated Amino Acids

Phosphorylated amino acids are involved in many cell regulatory networks; proteins containing these post-translational modifications are widely studied both experimentally and computationally. Simulations are used to investigate a wide range of structural and dynamic properties of biomolecules, such as ligand binding, enzyme-reaction mechanisms, and protein folding. However, the development of force field parameters for the simulation of proteins containing phosphorylated amino acids using the Amber program has not kept pace with the development of parameters for standard amino acids, and it is challenging to model these modified amino acids with accuracy comparable to proteins containing only standard amino acids. In particular, the popular ff14SB and ff19SB models do not contain parameters for phosphorylated amino acids. Here, the dihedral parameters for the side chains of the most common phosphorylated amino acids are trained against reference data from QM calculations adopting the ff14SB approach, followed by validation against experimental data. Finally, library files and corresponding parameter files are provided, with versions that are compatible with both ff14SB and ff19SB.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Persistent Charge-Density-Wave Order in Single-Layer TaSe 2

Understanding the collective electronic phases of two-dimensional (2D) materials requires a comprehensive investigation of the relation between lattice symmetry and electronic structure1-3. Single layers of transition metal dichalcogenides (TMDs) provide a material platform to study collective states such as charge density wave (CDW) and superconductivity4-7. By combining angle-resolved photoemission spectroscopy (ARPES), scanning tunneling microscopy/spectroscopy (STM/STS), and density functional theory (DFT) calculations, we present the electronic characterization of single-layer 1H-TaSe2 grown by molecular beam epitaxy (MBE). We demonstrate that 3×3 CDW order persists despite distinct changes in the low energy electronic structure highlighted by a reduction in the number of bands crossing the Fermi energy (EF) and corresponding modification of Fermi surface (FS) topology. Enhanced spin orbit coupling and lattice distortion in the single-layer limit play a crucial role in the formation of CDW order. Our findings provide a deeper understanding of the nature of CDW order in the 2D limit.

2D materials↗
DOE OSTI2013

Split of Chiral Degeneracy in Mechanical and Structural Properties of Oligopeptide-Polysaccharide Biomaterials

Enantiomeric biomaterials which are mirror images of each other are characterized by chiral degeneracy—identical structural characteristics and bulk material properties. The addition of another chiral component, d-polysaccharide, has been shown to split such degeneracy and result in two distinct biomaterials. Dynamic oscillatory rheometry and small-angle X-ray scattering demonstrate that the natural biochirality combination of l-peptides and d-polysaccharides assembles faster, has higher elastic moduli (G'), and is structurally more beneficial as opposed to the alternative d-peptide and d-polysaccharide combination. Chemical modifications of the OH-groups in α-d-glucose units in d-polysaccharides weaken such splitting of chiral degeneracy. These findings form a basis to design novel biomaterials and provide additional insight on why proteins and polysaccharides have oppoiste chirality in the biological world.

Taraban, Marc B.↗
DOE OSTI2016

Breaking a dark degeneracy with gravitational waves

We identify a scalar-tensor model embedded in the Horndeski action whose cosmological background and linear scalar fluctuations are degenerate with the concordance cosmology. The model admits a self-accelerated background expansion at late times that is stable against perturbations with a sound speed attributed to the new field that is equal to the speed of light. While degenerate in scalar fluctuations, self-acceleration of the model implies a present cosmological tensor mode propagation at ∼<95 % of the speed of light with a damping of the wave amplitude that is ∼>5 % less efficient than in general relativity. We show that these discrepancies are endemic to self-accelerated Horndeski theories with degenerate large-scale structure and are tested with measurements of gravitational waves emitted by events at cosmological distances. Hence, gravitational-wave cosmology breaks the dark degeneracy in observations of the large-scale structure between two fundamentally different explanations of cosmic acceleration—a cosmological constant and a scalar-tensor modification of gravity. The gravitational wave event GW150914 recently detected with the aLIGO instruments and its potential association with a weak short gamma-ray burst observed with the Fermi GBM experiment may have provided this crucial measurement.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Effects of human presence on African mammal waterhole attendance and temporal activity patterns

Abstract Human impacts on the environment and wildlife populations are increasing globally, threatening thousands of species with extinction. While wildlife‐based tourism is beneficial for educating tourists, generating income for conservation efforts, and providing local employment, more information is needed to understand how this industry may impact wildlife. In this study, we used motion‐activated cameras at 12 waterholes on a private game reserve in northern Namibia to determine if the presence of humans and permanent infrastructure affected mammal visits by examining their (1) number of visits, (2) time spent, and (3) diel activity patterns. Our results revealed no differences in the number of visits based on human presence for any of the 17 mammal species studied. However, giraffes ( Giraffe camelopardalis ) spent more time at waterholes before observer presence compared to during. Additionally, several species changed diel activity patterns when human observers were present. Notably, several carnivore and ungulate species increased overlap in their activity patterns during periods while humans were present relative to when humans were absent. These modifications of mammal temporal activity patterns due to human presence could eventually lead to changes in community structure and trophic dynamics because of altered predator–prey interactions. As humans continue to expand into wildlife habitats, and wildlife‐based tourism increases globally, it is imperative that we fully understand the effects of anthropogenic pressures on mammal behavior. Monitoring of wildlife behavioral changes in response to human activity is crucial to further develop wildlife tourism opportunities in a way that optimizes the impact of conservation goals.

Patterson, J. R. [Savannah River Ecology Lab, Warn↗
DOE OSTI2013

What a Difference a Dalton Makes: Bacterial Virulence Factors Modulate Eukaryotic Host Cell Signaling Systems via Deamidation

Pathogenic bacteria commonly deploy enzymes to promote virulence. These enzymes can modulate the functions of host cell targets. While the actions of some enzymes can be very obvious (e.g., digesting plant cell walls), others have more subtle activities. Depending on the lifestyle of the bacteria, these subtle modifications can be crucially important for pathogenesis. In particular, if bacteria rely on a living host, subtle mechanisms to alter host cellular function are likely to dominate. Several bacterial virulence factors have evolved to use enzymatic deamidation as a subtle posttranslational mechanism to modify the functions of host protein targets. Deamidation is the irreversible conversion of the amino acids glutamine and asparagine to glutamic acid and aspartic acid, respectively. Interestingly, all currently characterized bacterial deamidases affect the function of the target protein by modifying a single glutamine residue in the sequence. Deamidation of target host proteins can disrupt host signaling and downstream processes by either activating or inactivating the target. Despite the subtlety of this modification, it has been shown to cause dramatic, context-dependent effects on host cells. Several crystal structures of bacterial deamidases have been solved. All are members of the papain-like superfamily and display a cysteine-based catalytic triad. However, these proteins form distinct structural subfamilies and feature combinations of modular domains of various functions. Based on the diverse pathogens that use deamidation as a mechanism to promote virulence and the recent identification of multiple deamidases, it is clear that this enzymatic activity is emerging as an important and widespread feature in bacterial pathogenesis.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2015

Relationship between the defect structure and fluorine-ion conductivity of La{sub 1−y}Sr{sub y}F{sub 3−y} (0 ⩽ y ⩽ 0.15) crystals according to X-ray and neutron diffraction data

The defect structure of crystals of as-grown nonstoichiometric tysonite (LaF{sub 3} type) La{sub 1−y}Sr{sub y}F{sub 3−y} phase (y = 0, 0.05, 0.07, and 0.15) has been investigated by X-ray diffraction and neutron diffraction. A concentration-driven structural transition from the β-La{sub 1−y}Sr{sub y}F{sub 3−y} modification to the α-La{sub 1−y}Sr{sub y}F{sub 3−}y modification in the range y = 0.05–0.10 has been observed for the first time. This transition correlates with the maximum of fluorine-ion conductivity (y = 0.05 ± 0.02) and the maximum in the melting curve (y = 0.07 ± 0.03). β-LaF{sub 3} and β-La{sub 0.95}Sr{sub 0.05}F{sub 2.95} crystals belong to the trigonal system (sp. gr. P3̄c1, Z = 6) and are twinned according to the merohedral twin law. Fine changes in the fluorine sublattice of β-La{sub 0.95}Sr{sub 0.05}F{sub 2.95} increase conductivity σ{sub 293K} to 3 × 10{sup −4} S/cm; hence, these crystals can be used as fluorine-conducting solid electrolytes (FCSEs) in solid-state ionics devices. Additional possibilities of ion transport over twin joints are discussed. In α-La{sub 0.85}Sr{sub 0.15}F{sub 2.85} crystal the symmetry group changes to P6{sub 3}/mmc, Z = 2; it is not twinned and its fluorine-ion conductivity is reduced.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Review of the Stability/Capacity Trade-off in Silver Hollandite Lithium Battery Cathodes

ABSTRACT Highly detailed structural characterization is required to understand the discharge mechanism in order to effectively investigate α-MnO 2 structured lithium battery cathode materials. This paper discusses recent findings which elucidate the lithiation mechanism of silver-hollandite, Ag x Mn 8 O 16 . For Ag 1.2 Mn 8 O 16 , the structure is not significantly perturbed during the first 2 equivalents of lithiation and the electrochemistry is highly reversible. Upon 4 equivalents of lithiation, the structure becomes highly distorted, in correlation with capacity fade observed over 40 cycles. Notably, regarding capacity fade, modifications to Ag/Mn ratio are less impactful than modifications to the α-MnO 2 crystallite size. This is shown in comparisons of two materials with the same stoichiometry (Ag 1.4 Mn 8 O 16 ) and differing crystallite size (10 and 15 nm).

energy storage (including batteries and capacitors↗
DOE OSTI2016

Probing nuclear gluons with heavy flavors at an Electron-Ion Collider

We explore the feasibility of direct measurements of nuclear gluon densities using heavy-quark production (open charm, beauty) at a future Electron-Ion Collider (EIC). We focus on the regions x > 0.3 (EMC effect) and x ~ 0.05 -0.1 (antishadowing), where the nuclear modifications of the gluon density offer insight into non-nucleonic degrees of freedom and the QCD structure of nucleon-nucleon interactions. We describe the charm production rates and momentum distributions in nuclear deep-inelastic scattering (DIS) at large x_B, and comment on the possible methods for charm reconstruction using next-generation detectors at the EIC (pi/K identification, tracking, vertex detection).

Chudakov, Eugene↗
DOE OSTI2025

Review of Layered Transition Metal Oxide Materials for Cathodes in Sodium-Ion Batteries

The growing interest in sodium-ion batteries (SIBs) is driven by scarcity and the rising costs of lithium, coupled with the urgent need for scalable and sustainable energy storage solutions. Among various cathode materials, layered transition metal oxides have emerged as promising candidates due to their structural similarity to lithium-ion battery (LIB) counterparts and their potential to deliver high energy density at reduced costs. However, significant challenges remain, including limited capacity at high charge/discharge rates and structural instability during extended cycling. Addressing these issues is critical for advancing SIB technology toward industrial applications, particularly for large-scale energy storage systems. This review provides a comprehensive analysis of layered sodium transition metal oxides, focusing on their structural properties, electrochemical performance, and degradation mechanisms. Special attention is given to the intrinsic and extrinsic factors contributing to their instability, such as structural phase transitions, and cationic/anionic redox behavior. Additionally, recent advancements in material design strategies, including doping, surface modifications, and composite formation, are discussed to highlight the progress toward enhancing the stability and performance of these materials. This work aims to bridge the knowledge gaps and inspire further innovations in the development of high-performance cathodes for sodium-ion batteries.

Ahangari, Mehdi (ORCID:0000000345803969)↗
DOE OSTI2011

Strong Pinning in Thick YBa2Cu3O7 Layers Mediated by Catalysis of a New Long-period Metastable Cuprate Phase

Catalysts are widely utilized to promote reactions in liquid and gaseous phases but are rarely encountered in solid state synthesis. Here we use catalytically active (001) ceria buffers to modify the structure of the epitaxial high temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7}. The modification is achieved by catalytically-assisted synthesis of a previously unknown metastable phase. The new phase, a long-period (3.5 nm) perovskite, intercalates into the YBa{sub 2}Cu{sub 3}O{sub 7} matrix without negatively affecting the critical temperature of the film. Analysis of electron microscopy and synchrotron x-ray diffraction data allow identification of the phase as a long-period YBa{sub 2}Cu{sub 3}O{sub 7} derivative formed through short-range cation displacement. The 0.8 {micro}m thick films exhibit strong enhancement of the critical current density, reaching a maximum of 4.2 MA/cm{sup 2} at 77 K. The result emphasizes the critical role of catalysis for synthesis of novel complex materials.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Apparatus and method for electrochemical modification of liquids

An apparatus for electrochemical modification of liquid streams employing an electrolytic cell which includes an anode compartment defined by an anode structure where oxidation is effected, containing a liquid electrolyte anolyte, and a cathode compartment defined by a cathode structure where reduction is effected containing a liquid electrolyte catholyte. In addition, the electrolytic cell includes at least one additional compartment arranged at least partially between the anode compartment and the cathode compartment and separated from the anode compartment and the cathode compartment by a separator structure arranged to supports ionic conduction of current between the anode structure and the cathode structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗