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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 235 records · Page 13
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Pillared Laminar Vermiculite Membranes with Tunable Monovalent and Multivalent Ion Selectivity

Effective membrane separation of Li + from Na + and Mg 2+ is crucial for lithium extraction from water yet challenging for conventional polymeric membranes. Two dimensional (2D) membranes with ordered laminar structures and tunable physicochemical properties offer distinctive ion-sieving capabilities promising for lithium extraction. Recently, phyllosilicates are introduced as abundant and cost-effective source materials for such membranes. However, their water instability and low inherent ion transport selectivity hinder practical applications. Herein, a new class of laminar membranes with excellent stability and tunable ion sieving is reported by incorporating inorganic alumina pillars into vermiculite interlayers. Crosslinking vermiculite flakes with alumina pillars significantly strengthens interlamellar interactions, resulting in robust water stability. Doping of Na + before the pillaring process reverses the membrane's surface charge, substantially boosting Li + separation from multivalent cations via electrostatic interactions. Lithium extraction is often complicated by the presence of co-existing monovalent cations (e.g., Na + ) at higher concentrations. Here, by introducing excess Na + into the membrane after the pillaring process, the separation of Li + from monovalent cations is enhanced through steric effects. This work realizes both monovalent/multivalent and monovalent/monovalent selective ion sieving with the same membrane platform. A separation mechanism is proposed based on Donnan exclusion and size exclusion, providing new insights for membrane design for resource recovery applications.

2D materials↗
DOE OSTI2023

Characterizing the Self-Assembly Properties of Monoolein Lipid Isosteres

Living cells feature lipid compartments which exhibit a variety of shapes and structures that assist essential cellular processes. Many natural cell compartments frequently adopt convoluted nonlamellar lipid architectures that facilitate specific biological reactions. Improved methods for controlling the structural organization of artificial model membranes would facilitate investigations into how membrane morphology affects biological functions. Monoolein (MO) is a single-chain amphiphile which forms nonlamellar lipid phases in aqueous solution and has wide applications in nanomaterial development, the food industry, drug delivery, and protein crystallization. However, even if MO has been extensively studied, simple isosteres of MO, while readily accessible, have seen limited characterization. An improved understanding of how relatively minor changes in lipid chemical structure affect self assembly and membrane topology could instruct the construction of artificial cells and organelles for modeling biological structures and facilitate nanomaterial-based applications. Here, we investigate the differences in self-assembly and large-scale organization between MO and two MO lipid isosteres. We show that replacing the ester linkage between the hydrophilic headgroup and hydrophobic hydrocarbon chain with a thioesther or amide functional group results in the assembly of lipid structures with different phases not resembling those formed by MO. Using light and cryo-electron microscopy, small-angle X-ray scattering, and infrared spectroscopy, we demonstrate differences in the molecular ordering and large-scale architectures of the self-assembled structures made from MO and its isosteric analogues. These results improve our understanding of the molecular underpinnings of lipid mesophase assembly and may facilitate the development of MO-based materials for biomedicine and as model lipid compartments.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Neutrons reveal the dynamics of leaf thylakoids in living plants

The study is the first known exploration of photosynthetic membranes dynamics in living plants by high resolution quasielastic neutron scattering spectroscopy. We investigated the mobility and flexibility of thylakoid membranes in common duckweed (Landoltia punctata) and identified dynamics across various length scales corresponding to individual membranes and membranes stack. We employed classical models typically used to study lipid bilayers to characterize the undulation modes and rigidity of the membranes and reveal how structural variations influence the observed complex dynamics. Our findings show that the stacks of thylakoids in duckweed behave as rigid systems, exhibiting an effective bending coefficient in the lower range associated with surfactant membranes. In contrast, the single thylakoid leaflets display greater apparent flexibility and are well situated within the bi-continuous surfactant phase dynamics. While our observations enhance the understanding of the intricate architecture and mobility of photosynthetic cellular machinery, they also highlight the limitations of applying ideal lipid membranes models to describe complex biological systems. This work opens more questions and the need for further investigations across extended length and time scales, as well as the importance of rigorous sample preparation and experimental control.

Applied physics↗
DOE OSTI2024

High-Performance AEM LTE with Advanced Membranes, Ionomers and PGM-Free Electrodes

Alkaline low temperature electrolysis (LTE) systems enjoy several potential advantages over acid-based LTE systems including facile oxygen evolution reaction (OER) kinetics and electrodes that can use little to no platinum group metals (PGM). The polymer membranes and membrane electrode assembly (MEA) structures going into alkaline electrochemical systems have seen significant advances in recent years. The objective of this project is to combine state-of-the-art alkaline polymer electrolyzer components into one optimized membrane electrode assembly (MEA) system to achieve DOE low temperature electrolysis (LTE) goals. The benefit of individual component advances cannot be fully appreciated until all aspects and components of the MEA are working at an equally high level of performance. New electrode fabrication methods were developed where solvent cast catalyst/ionomer solutions were used in place of insoluble ionomers to significantly improve adhesion. The membranes were improved in terms of durability and mechanical properties. The OER and HER catalysts were improved and made more durable.

08 HYDROGEN↗
DOE OSTI2023

Polyvinyl Alcohol Anion Exchange Resin Composite Membrane with Co@Cu Core–Shell Particles for Direct Borohydride Fuel Cell Applications

We report a polyvinyl alcohol anion exchange resin composite membrane, functionalized with Co and Cu ions, is reported for use in direct borohydride fuel cells (DBFCs). The CoCu-functionalized membrane has a 30.5% lower fuel permeability than that of a blank membrane. Meanwhile, the cell performance of the DBFC can also be improved by employing the CoCu-functionalized membrane, reaching a maximum power density of 304 mW·cm –2 at 60 °C. High-resolution fluorescence images directly demonstrate the formation of Cu/Co core–shell structure microparticles in the CoCu membrane, which not only reduces the Co content but also increases the active surface area of Co species in CoCu-functionalized membranes, resulting in the improvement of cell performance.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Fabrication and characterization of dextran/zein hybrid electrospun fibers with tailored properties for controlled release of curcumin

Abstract BACKGROUND In recent years, there has been considerable interest in the use of biopolymer electrospun nanofibers for various food applications due to the biocompatibility, biodegradability, and high loading capacity. Herein, we fabricated and characterized novel hybrid electrospun fibers from dextran (50%, w/v ) and zein (0–30%, w/v ) solutions, and the effects of various zein concentrations on the properties of the hybrid electrospun fibers were investigated. RESULTS When zein was added at low concentrations (5% and 10%), dextran and zein showed poor miscibility, as reflected by significantly decreased viscosity of the solutions, and the poor mechanical properties of the derived fiber membranes. When zein was added at medium concentrations (15–25%), hydrogen bonds were formed between dextran and zein molecules, as indicated by the red shift of Fourier‐transform infrared bands and β‐sheet to α‐helix structural transformations. The fiber membranes electrospun from a solution with 25% zein showed the most hydrophobic surface, with a water contact angle of 116.9°. The homogenous dispersion of dextran and zein resulted in improved mechanical properties for fibers electrospun from a solution with 30% zein. Curcumin encapsulating dextran/zein electrospun fibers exhibited effective radical scavenging activity and ferric reducing power, along with the desired controlled release behavior for curcumin delivery. CONCLUSION Food grade dextran/zein hybrid electrospun fibers demonstrated tunable properties, and appear to be promising as delivery systems for bioactive and edible antimicrobial food packaging. © 2021 Society of Chemical Industry.

Luo, Shiyuan↗
DOE OSTI2021

Antineoplastic activity of Salmonella Typhimurium outer membrane nanovesicles

Highlights: • ST-OMVs is a promising antitumor monotherapy or as an adjuvant to chemotherapies. • ST-OMVs downregulated Ki-67 and upregulated CD49b immune-expression. • ST-OMVs downregulated angiogenesis by inhibiting VEGF gene expression. • ST-OMVs increased tumor cells apoptosis and autophagy (increased caspase-3and Beclin1). Nano-sized Gram-negative bacterial outer membrane vesicles possess unique structural and immunostimulatory effects that could be exploited to regress tumors by alerting the host immune system and reversing the immunosuppressive tumor microenvironment. The current study was conducted to investigate the antitumor activity of the outer membrane vesicles (ST-OMVs) of Salmonella Typhimurium ATCC 14028, in vitro in human colorectal carcinoma (HTC116), breast cancer (MCF-7), and hepatocellular carcinoma (HepG2) cell lines and in vivo in Ehrlich solid carcinoma-bearing mice model either as a mono-immunotherapy or as an adjuvant to a commonly used conventional chemotherapy. In addition, we investigated the safety of ST-OMVs. Adult Swiss albino female mice with transplanted Ehrlich solid carcinoma were treated with either ST-OMVs, paclitaxel or a combination of both. Tumor volume, growth inhibition rate, quantitative RT-PCR of Bax and VEGF genes expression, histopathology and immune-expression of caspase-3, Beclin-1, CD49b and Ki-67 were all analyzed. Our results showed that ST-OMVs significantly decreased tumor volume, significantly increased tumor growth inhibition rate, up-regulated the immunohistochemical expression of caspase-3, Beclin-1, and CD49b (enhanced recruitment of NK cells). Furthermore, ST-OMVs down-regulated the expression of Ki-67, increased Bax gene expression and decreased VEGF gene expression as detected by qRT-PCR analysis. Histologically, ST-OMVs promoted apoptosis, decreased tumor invasion and mitotic activities. Moreover, ST-OMVs showed a remarkable cytotoxic activity in various investigated in vitro cancer cell lines. Our findings demonstrate potential antitumor activity of ST-OMVs that might be used as a promising safe antitumor immunotherapy or an adjuvant to conventional chemotherapeutic drugs, resolving some of their problems.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Theoretical Pathway toward Improved Reverse Osmosis Membrane Selectivity for Neutral Solutes: Inspiration from Gas Separations

We report highly rigid membrane materials with tailored structures have exhibited permeabilities and selectivities that exceed the polymer upper bound in gaseous and organic solvent separations for challenging mixtures containing species that are similar in size and shape. One potential question is whether such membrane materials can maintain meaningful guest diffusivities in situations where the microporous spaces are essentially full of guest molecules. Here, we use a simplified transition state theory approach to estimate the diffusivity of water and small organics within a microporous membrane. The transition state theory model is parameterized using experimental values from zeolites and carbon molecular sieve materials found in the literature. We demonstrate the differences in transport and Maxwell–Stefan diffusivities based on guest species loading with different isotherm behaviors. These calculations theorize a path forward for highly selective reverse osmosis membranes for aqueous phase separations.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Advanced PEM Electrolyzer Membrane for Hydrogen Crossover Mitigation

An unintended reaction in the electrochemical conversion of water to hydrogen in proton exchange membrane (PEM) electrolyzers is the crossover of hydrogen from the anode to the oxygen-containing cathode through the membrane, creating hydrogen losses and safety concerns. Efforts to date have focused on embedding platinum catalysts in perfluorosulfonic (PFSA) membranes to convert H 2 to protons. The objective of this project is to design and develop hydrocarbon (HC) proton exchange membranes (PEMs) that can help overcome the risk of high H 2 crossover in current PEM electrolyzer (ELX) stacks by designing and optimizing the gas recombination catalyst (GRC) within the membrane and membrane electrode assembly (MEA) structure.

08 HYDROGEN↗
DOE OSTI2025

Clay Reimagined: Phyllosilicates as Future Membrane Technologies

Membrane technologies have made critical advances in resource recovery, water purification, and energy systems. However, it is difficult to systematically tune properties of traditional polymer membranes, and researchers have struggled to deliver challenging, advanced separations using these platforms. In recent years, membranes based on 2D materials have drawn attention for molecular-scale separations due to their unique properties, most notably their tunable nanoscale interlayer properties. Among the diverse family of 2D materials, phyllosilicates, a broad class of naturally abundant clay minerals, offer significant advantages in cost and scalability over synthetic 2D materials, positioning them as promising candidates for advanced membrane technologies. Their inherent structural and chemical properties, strategies for tailoring selective transport pathways, and recent advancements across applications including ion separation, water treatment, and energy conversion are discussed. Finally, key challenges and opportunities are outlined to guide future research in leveraging phyllosilicate membranes for high-performance separation technologies.

energy storage and conversion↗
DOE OSTI2026

Protocol for Engineered Compositional Asymmetry Within Nanodiscs

Membrane proteins remain the most challenging targets for structural characterization, yet their elucidation provides valuable insights into protein function, disease mechanisms, and drug specificity. Structural biology platforms have advanced rapidly in recent years, notably through the development and implementation of nanodiscs—discoidal lipid–protein complexes that encapsulate and solubilize membrane proteins within a controlled, native-like environment. While nanodiscs have become powerful tools for studying membrane proteins, faithfully reconstituting the compositional asymmetry intrinsic to nearly all biological membranes has not yet been achieved. Proper membrane leaflet lipid distribution is critical for accurate protein folding, stability, and insertion. Here, we share a protocol for reconstituting tailored compositional asymmetry within nanodiscs through membrane extraction from giant unilamellar vesicles (GUVs) treated with a leaflet-specific methyl-β-cyclodextrin (mβCD) lipid exchange. Nanodisc asymmetry is verified through a geometric approach: biotin-DPPE-preloaded mβCD engages in lipid exchange with the outer leaflet of POPC GUVs solubilized by the lipid-free membrane scaffold protein (MSP) Δ49ApoA-I to form nanodisc structures. Once isolated, nanodiscs are introduced to the biotin-binding bacterial protein streptavidin. High-speed atomic force microscopy imaging depicts nanodisc–dimer complexes, indicating that biotin-DPPE was successfully reconstituted into a single leaflet of the nanodiscs. This finding outlines the first step toward engineering tailored nanodisc asymmetry and mimicking the native environment of integral proteins—a potentially powerful tool for accurately reconstituting and structurally analyzing integral membrane proteins whose functions are modulated by lipid asymmetry.

Biological and medical sciences↗
DOE OSTI2021

Structural basis of LAIR1 targeting by polymorphic Plasmodium RIFINs

RIFIN, a large family of Plasmodium variant surface antigens, plays a crucial role in malaria pathogenesis by mediating immune suppression through activation of inhibitory receptors such as LAIR1, and antibodies with LAIR1 inserts have been identified that bind infected erythrocytes through RIFIN. However, details of RIFIN-mediated LAIR1 recognition and receptor activation have been unclear. Here, we use negative-stain EM to define the architecture of LAIR1-inserted antibodies and determine crystal structures of RIFIN-variable 2 (V2) domain in complex with a LAIR1 domain. These structures reveal the LAIR1-binding region of RIFIN to be hydrophobic and membrane-distal, to exhibit extensive structural diversity, and to interact with RIFIN-V2 in a one-to-one fashion. Through structural and sequence analysis of various LAIR1 constructs, we identify essential elements of RIFIN-binding on LAIR1. Furthermore, a structure-derived LAIR1-binding sequence signature ascertained >20 LAIR1-binding RIFINs, including some from P. falciparum field strains and Plasmodium species infecting gorillas and chimpanzees.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Calcium Sulfate and Calcium Carbonate Scaling of Thin-Film Composite Polyamide Reverse Osmosis Membranes with Surface-Tethered Polyacrylic Acid Chains

The gypsum and calcite scaling propensities of the thin-film composite polyamide (PA-TFC) reverse osmosis (RO) membrane, modified with a tethered surface layer of polyacrylic acid (PAA) chains, was evaluated and compared to the scaling of selected commercial RO membranes. The tethered PAA layer was synthesized onto a commercial polyamide membrane (i.e., base-PA) via atmospheric pressure plasma-induced graft polymerization (APPIGP). The PAA nano-structured (SNS) base-PA membrane (SNS-PAA-PA) was scaled to a lesser degree, as quantified by a lower permeate flux decline and surface imaging, relative to the tested commercial membranes (Dow SW30, Toray SWRO, and BWRO). The cleaning of gypsum-scaled membranes with D.I. water flushing achieved 100% water permeability recovery for both the SNS-PAA-PA and Dow SW30 membranes, relative to 92–98% permeability restoration for the Toray membranes. The calcium carbonate scaling of SNS-PAA-PA membranes was also lower relative to the commercial membranes, but permeability recovery after D.I. water cleaning was somewhat lower (94%) but consistent with the level of surface scale coverage. In contrast, the calcite and gypsum-scaled membrane areas of the commercial membranes post-cleaning were significantly higher than for the SNS-PAA-PA membrane but with 100% permeability recovery, suggesting the potential for membrane damage when mineral scaling is severe.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Native Top-Down Mass Spectrometry Characterization of Model Integral Membrane Protein Bacteriorhodopsin

Bacteriorhodopsin (bR) from Halobacterium salinarum has been a model system for structural biology and is a structural template for the characterization of membrane G-protein couple receptors (GPCRs) in particular. Here, in this study, wild-type bacteriorhodopsin and two single-residue mutants were characterized by native top-down mass spectrometry (nTD-MS) with Orbitrap-based high-energy collision dissociation (HCD) and electron capture dissociation (ECD). After in-source dissociation ejected the membrane protein from detergent micelles, high-resolution native MS measurement allowed for identification of multiple proteoforms as well as lipid-bound forms. Further top-down MS measurements by HCD produced a large number of product ions for in-depth sequencing and unambiguous localization of post-translational modifications. For the first time, native TD-MS with ECD was used to characterize an integral membrane protein. ECD yielded fragments originating from all helices and loop regions, even accessing a sequence stretch that HCD could not. Combining HCD and ECD fragmentation patterns significantly enhanced the sequence coverage of bR. We propose bR to be a model analyte for testing nTD-MS performance for membrane proteins.

crystal cleavage↗
DOE OSTI2020

Structural Insights into the SPRED1-Neurofibromin-KRAS Complex and Disruption of SPRED1-Neurofibromin Interaction by Oncogenic EGFR

Sprouty-related, EVH1 domain-containing (SPRED) proteins negatively regulate RAS/mitogen-activated protein kinase (MAPK) signaling following growth factor stimulation. This inhibition of RAS is thought to occur primarily through SPRED1 binding and recruitment of neurofibromin, a RasGAP, to the plasma membrane. Here, we report the structure of neurofibromin (GTPase-activating protein [GAP]-related domain) complexed with SPRED1 (EVH1 domain) and KRAS. The structure provides insight into how the membrane targeting of neurofibromin by SPRED1 allows simultaneous interaction with activated KRAS. SPRED1 and NF1 loss-of-function mutations occur across multiple cancer types and developmental diseases. Analysis of the neurofibromin-SPRED1 interface provides a rationale for mutations observed in Legius syndrome and suggests why SPRED1 can bind to neurofibromin but no other RasGAPs. We show that oncogenic EGFR(L858R) signaling leads to the phosphorylation of SPRED1 on serine 105, disrupting the SPRED1-neurofibromin complex. The structural, biochemical, and biological results provide new mechanistic insights about how SPRED1 interacts with neurofibromin and regulates active KRAS levels in normal and pathologic conditions.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Characterization of Gramicidin A in Triblock and Diblock Polymersomes and Hybrid Vesicles via Continuous Wave Electron Paramagnetic Resonance Spectroscopy

Studying membrane proteins in a native environment is crucial to understanding their structural and/or functional studies. Often, widely accepted mimetic systems have limitations that prevent the study of some membrane proteins. Micelles, bicelles, and liposomes are common biomimetic systems but have problems with membrane compatibility, limited lipid composition, and heterogeneity. To overcome these limitations, polymersomes and hybrid vesicles have become popular alternatives. Polymersomes form from amphiphilic triblock or diblock copolymers and are considered more robust than liposomes. Hybrid vesicles are a combination of lipids and block copolymers that form vesicles composed of a mixture of the two. These hybrid vesicles are appealing because they have the native lipid environment of bilayers but also the stability and customizability of polymersomes. Gramicidin A was incorporated into these polymersomes and characterized using continuous wave electron paramagnetic resonance (CW-EPR) and transmission electron microscopy (TEM). EPR spectroscopy is a powerful biophysical technique used to study the structure and dynamic properties of membrane proteins in their native environment. Spectroscopic studies of gramicidin A have been limited to liposomes; in this study, the membrane peptide is studied in both polymersomes and hybrid vesicles using CW-EPR spectroscopy. Lineshape analysis of spin-labeled gramicidin A revealed linewidth broadening, suggesting that the thicker polymersome membranes restrict the motion of the spin label more when compared to liposome membranes. Statement of Significance: Understanding membrane proteins’ structures and functions is critical in the study of many diseases. In order to study them in a native environment, membrane mimetics must be developed that can be suitable for obtaining superior biophysical data quality to characterize structural dynamics while maintaining their native functions and structures. Many currently widely accepted methods have limitations, such as a loss of native structure and function, heterogeneous vesicle formation, restricted lipid types for the vesicle formation for many proteins, and experimental artifacts, which leaves rooms for the development of new biomembrane mimetics. The triblock and diblock polymersomes and hybrid versicles utilized in this study may overcome these limitations and provide the stability and customizability of polymersomes, keeping the biocompatibility and functionality of liposomes for EPR studies of membrane proteins.

59 BASIC BIOLOGICAL SCIENCES↗