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All sourcesNASA NTRSDOE OSTI
NASA NTRS2010

The Mineralogy of Circumstellar Silicates Preserved in Cometary Dust

Interplanetary dust particles (IDPs) contain a record of the building blocks of the solar system including presolar grains, molecular cloud material, and materials formed in the early solar nebula. Cometary IDPs have remained relatively unaltered since their accretion because of the lack of parent body thermal and aqueous alteration. We are using coordinated transmission electron microscope (TEM) and ion microprobe studies to establish the origins of the various components within cometary IDPs. Of particular interest is the nature and abundance of presolar silicates in these particles because astronomical observations suggest that crystalline and amorphous silicates are the dominant grain types produced in young main sequence stars and evolved O-rich stars. Five circumstellar grains have been identified including three amorphous silicate grains and two polycrystalline aggregates. All of these grains are between 0.2 and 0.5 micrometers in size. The isotopic compositions of all five presolar silicate grains fall within the range of presolar oxides and silicates, having large (17)O-enrichments and normal (18)O/(16)O ratios (Group 1 grains from AGB and RG stars). The amorphous silicates are chemically heterogeneous and contain nanophase FeNi metal and FeS grains in a Mg-silicate matrix. Two of the amorphous silicate grains are aggregates with subgrains showing variable Mg/Si ratios in chemical maps. The polycrystalline grains show annealed textures (equilibrium grains boundaries, uniform Mg/Fe ratios), and consist of 50-100 nm enstatite and pyrrhotite grains with lesser forsterite. One of the polycrystalline aggregates contains a subgrain of diopside. The polycrystalline aggregates form by subsolidus annealing of amorphous precursors. The bulk compositions of the five grains span a wide range in Mg/Si ratios from 0.4 to 1.2 (avg. 0.86). The average Fe/Si (0.40) and S/Si (0.21) ratios show a much narrower range of values and are approximately 50% of their solar abundances. The latter observation may indicate a decoupling of the silicate and sulfide components in grains that condense in stellar outflows. The amorphous silicate grains described here were not extensively affected by irradiation, sputtering, or thermal processing and may represent relatively pristine circumstellar grains. They are strong candidates for the "dirty silicates" in astronomical observations of circumstellar dust shells. The polycrystalline grains were originally amorphous silicate grains that were likely annealed in the early solar nebula but the processing was not sufficient to erase their anomalous oxygen isotopic compositions.

Keller, L. P.↗
NASA NTRS2011

Hydrofocusing Bioreactor Produces Anti-Cancer Alkaloids

A methodology for growing three-dimensional plant tissue models in a hydrodynamic focusing bioreactor (HFB) has been developed. The methodology is expected to be widely applicable, both on Earth and in outer space, as a means of growing plant cells and aggregates thereof under controlled conditions for diverse purposes, including research on effects of gravitation and other environmental factors upon plant growth and utilization of plant tissue cultures to produce drugs in quantities greater and at costs lower than those of conventional methodologies. The HFB was described in Hydro focus - ing Bioreactor for Three-Dimensional Cell Culture (MSC-22358), NASA Tech Briefs, Vol. 27, No. 3 (March 2003), page 66. To recapitulate: The HFB offers a unique hydrofocusing capability that enables the creation of a low-shear liquid culture environment simultaneously with the herding of suspended cells and tissue assemblies and removal of unwanted air bubbles. The HFB includes a rotating cell-culture vessel with a centrally located sampling port and an internal rotating viscous spinner attached to a rotating base. The vessel and viscous spinner can be made to rotate at the same speed and direction or different speeds and directions to tailor the flow field and the associated hydrodynamic forces in the vessel in order to obtain low-shear suspension of cells and control of the locations of cells and air bubbles. For research and pharmaceutical-production applications, the HFB offers two major benefits: low shear stress, which promotes the assembly of cells into tissue-like three-dimensional constructs; and randomization of gravitational vectors relative to cells, which affects production of medicinal compounds. Presumably, apposition of plant cells in the absence of shear forces promotes cell-cell contacts, cell aggregation, and cell differentiation. Only gentle mixing is necessary for distributing nutrients and oxygen. It has been postulated that inasmuch as cells in the simulated microgravitation of an HFB do not need to maintain the same surface forces as in normal Earth gravitation, they can divert more energy sources to growth and differentiation and, perhaps, to biosynthesis of greater quantities of desired medicinal compounds. Because one can adjust the HFB to vary effective gravitation, one can also test the effects of intermediate levels of gravitation on biosynthesis of various products. The potential utility of this methodology for producing drugs was demonstrated in experiments in which sandalwood and Madagascar periwinkle cells were grown in an HFB. The conditions in the HFB were chosen to induce the cells to form into aggregate cultures that produced anti-cancer indole alkaloids in amounts greater than do comparable numbers of cells of the same species cultured according to previously known methodologies. The observations made in these experiments were interpreted as suggesting that the aggregation of the cells might be responsible for the enhancement of production of alkaloids.

Gonda, Steve R.↗
NASA NTRS2012

Analyses of Cometary Silicate Crystals: DDA Spectral Modeling of Forsterite

Comets are the Solar System's deep freezers of gases, ices, and particulates that were present in the outer protoplanetary disk. Where comet nuclei accreted was so cold that CO ice (approximately 50K) and other supervolatile ices like ethane (C2H2) were preserved. However, comets also accreted high temperature minerals: silicate crystals that either condensed (greater than or equal to 1400 K) or that were annealed from amorphous (glassy) silicates (greater than 850-1000 K). By their rarity in the interstellar medium, cometary crystalline silicates are thought to be grains that formed in the inner disk and were then radially transported out to the cold and ice-rich regimes near Neptune. The questions that comets can potentially address are: How fast, how far, and over what duration were crystals that formed in the inner disk transported out to the comet-forming region(s)? In comets, the mass fractions of silicates that are crystalline, f_cryst, translate to benchmarks for protoplanetary disk radial transport models. The infamous comet Hale-Bopp has crystalline fractions of over 55%. The values for cometary crystalline mass fractions, however, are derived assuming that the mineralogy assessed for the submicron to micron-sized portion of the size distribution represents the compositional makeup of all larger grains in the coma. Models for fitting cometary SEDs make this assumption because models can only fit the observed features with submicron to micron-sized discrete crystals. On the other hand, larger (0.1-100 micrometer radii) porous grains composed of amorphous silicates and amorphous carbon can be easily computed with mixed medium theory wherein vacuum mixed into a spherical particle mimics a porous aggregate. If crystalline silicates are mixed in, the models completely fail to match the observations. Moreover, models for a size distribution of discrete crystalline forsterite grains commonly employs the CDE computational method for ellipsoidal platelets (c:a:b=8.14x8.14xl in shape with geometrical factors of x:y:z=1:1:10, Fabian et al. 2001; Harker et al. 2007). Alternatively, models for forsterite employ statistical methods like the Distribution of Hollow Spheres (Min et al. 2008; Oliveira et al. 2011) or Gaussian Random Spheres (GRS) or RGF (Gielen et al. 200S). Pancakes, hollow spheres, or GRS shapes similar to wheat sheaf crystal habit (e.g., Volten et al. 2001; Veihelmann et al. 2006), however, do not have the sharp edges, flat faces, and vertices seen in images of cometary crystals in interplanetary dust particles (IDPs) or in Stardust samples. Cometary forsterite crystals often have equant or tabular crystal habit (J. Bradley). To simulate cometary crystals, we have computed absorption efficiencies of forsterite using the Discrete Dipole Approximation (DDA) DDSCAT code on NAS supercomputers. We compute thermal models that employ a size distribution of discrete irregularly shaped forsterite crystals (nonspherical shapes with faces and vertices) to explore how crystal shape affects the shape and wavelength positions of the forsterite spectral features and to explore whether cometary crystal shapes support either condensation or annealing scenarios (Lindsay et al. 2012a, b). We find forsterite crystal shapes that best-fit comet Hale-Bopp are tetrahedron, bricks or brick platelets, essentially equant or tabular (Lindsay et al. 2012a,b), commensurate with high temperature condensation experiments (Kobatake et al. 2008). We also have computed porous aggregates with crystal monomers and find that the crystal resonances are amplified. i.e., the crystalline fraction is lower in the aggregate than is derived by fitting a linear mix of spectral features from discrete subcomponents, and the crystal resonances 'appear' to be from larger crystals (Wooden et al. 2012). These results may indicate that the crystalline mass fraction in comets with comae dominated by aggregates may be lower than deduced by popular methods that only emoy ensembles of discrete crystals.

Wooden, Diane↗
NASA NTRS2017

3-D-Observation of Matrix of MIL 090657 Meteorite by Absorption-Phase Tomography

MIL 090657 meteorite (CR2.7) is one of the least altered primitive carbonaceous c hondrites [1]. This meteorite has amorphous silicates like GEMS (glass with embedded metal and sulfide), which are characteristically contained in cometary dust, in matrix [2,3] as with the Paris meteorite [4]. Three lithologies have been recognized; lithology-1 (L 1) dominated by submicron anhydrous silicates, lithology-2 (L2) by GEMS-like amorphous silicates and lithology-3 (L3) by phyllosilicates [2]. Organic materials are abundant in L 1 and L2 [2,3]. L 1 and L2 were further divided into sub-lithology respectively based on their textures and compositions [5]. These studies were performed by 2D SEM and TEM observations of sample surfaces and thin sections that are unable to reveal what constitute each lithology and how these lithologies are distributed and related to each other. This information will provide important insights into alteration and aggregation processes on asteroids and in the early solar nebula. In this study, MIL 090657 matrix was examined in 3D using two types of X-ray tomography; DET (dual-energy tomography) [6] and SIXM (scanning-imaging X-ray microscopy) [7]. Mineral phases can be discriminated based on absorption contrasts at two different X-ray energies in DET. In SIXM, materials composed of light elements such as water or organic materials can be identified based on phase and absorption contrasts. By combining these methods, we can discriminate not only organic materials from voids but also hydrous alteration products, such as hydrated silicates and carbonates, from anhydrous minerals [8]. In this study, we first observed cross sections of MIL 090657 matrix fragments C1 00 mm) in detail using FE-SEM/ EDS. Based on the results, three house-shaped samples (3 0 -50 mm) were extracted from L 1, L2 and their boundary (H1, H3 and H5, respectively) using FIB. 3D imaging of these samples were conducted at BL47XU of SPring-8, a synchrotron radiation facility, with -30-40 nm/ voxel and - 70-80 nm/ voxel at 7keV and 8keV in DET and -100 nm/ voxel at 8keV in SIXM. We found new lithologies that we named L4, L5 and L6 in H1 and H3 in addition to L 1 and L2. L4. L5 and L6 are mainly composed of probably phyllosilicates with different Fe contents. Sulfide and framboidal magnetite were recognized in L4. L5 includes magnetite and carbonate and L6 includes anhydrous silicates having cracks inside. L 1, L2, L4 and L5 are porous while few voids were observed in L6. L4 adjoins to L 1 with boundary, which is not very distinct. L2, L5 and L6 adjoin to each other, and the boundaries of L6 with L2 and L5 are clear. In H5, coarse mineral grains C5-1 0 mm) such as Fe-metal and enstatite are present in L 1 and L2. L 1-L2 boundary is not sharp in 3 D. In conclusion, we found a variety of lithologies by 3D observation for the first time, suggesting that t he MIL 0 90657 meteorite experienced complex alteration and aggregation histories. As L2 is dominated by amorphous silicates, which are extremely susceptible to aqueous alteration, t his is p resumed to be t he most primitive lithology. The contact between L2 and phyllosilicate-bearing lithologies (L5 and L6) with clear boundaries indicates that they were aggregated after aqueous alteration of L5 and L6. The indistinct boundary between L 1 and L2 is suggesting that these two lithologies might originally be the same aggregate composed of amorphous silicates and coarse mineral grains. L 1 might have experienced weak aqueous alteration followed by mild thermal alteration [2], while L2 did not undergo aqueous alteration.

Miyama, Sugimoto↗
NASA NTRSDate not supplied

Understanding amyloids to prevent biofilm formation in space

There is a pressing need to search for novel approaches to combat biofilm formation, both in space and in medical applications. Many proteins have the ability to form ordered aggregates called amyloids. Amyloids are known to be an important part of biofilms. The use of anti-amyloid drugs is a novel venue for the development of antimicrobial agents. The ultrastructure of the amyloid aggregate shows a high packing of proteins, the second-order structure of which is dominated by β-sheets. The ability to form an amyloid aggregate is especially typical for proteins containing domains (protein fragments) with sufficient lability to arrange themselves in a tight β-sheet structure. Bioinformatics tools allow the prediction of such behavior of proteins in genomic data. We use GeneLab data of microbial populations identified aboard the International Space Station and other spacecraft to look for bacterial species that utilize amyloid aggregation in biofilm formation. We use a combined bioinformatic approach with a relatively high throughput molecular biology assay and biophysical assays to evaluate the anti-amyloid anti-biofilm approach. The significance of the research extends from understanding basic microbial community responses to spaceflight, to biofouling of the built environments in space as well as the long-term health of astronauts. Bioinformatics shows that onboard the ISS, bacterial species produce far more amyloid and prion proteins than are currently verified, hence their role in bacterial ecosystems is largely unknown. As we propose there is a link between amyloid formation in space and biofilm production, this research should lead to new paths for biofilm remediation in space.

Tomasz Zajkowski↗
NASA NTRS2023

Colorimetric and Label-Free Optical Detection of Pb 2+ Ions via Colloidal Gold Nanoparticles

The detection of Lead (Pb) heavy metal in water is crucial in many chemical processes as it is associated with serious health hazard. Here, we report the selective and precise colorimetric detection of Pb 2+ ions in water exploiting the mechanisms of aggregation and self-assembly of Glutathione (GSH) functionalized gold nanoparticles (GNPs). The carboxyl functional groups are available to create coordination complexes with Pb 2+ inducing aggregation amongst the GSH-GNPs in the presence of Pb 2+ due to the chelation of the GSH ligands. The resulting aggregation of amongst the GSHGNPs in the presence of Pb2+ increases the aggregate size depending on available Pb 2+ ions affecting the plasmonic coupling. This causes in a substantial shift in the plasmon wavelength to a longer wavelength side with increasing Pb 2+ concentration, resulting in a red-to-blue colorimetric or visual change, enabling instant determination of lead content in water.

calorimetric detection↗
DOE OSTI2024

A General Approach to Activate Second‐Scale Room Temperature Photoluminescence in Organic Small Molecules

Organic small molecules that exhibit second‐scale phosphorescence at room temperature are of interest for potential applications in sensing, anticounterfeiting, and bioimaging. However, such materials systems are uncommon—requiring millisecond to second‐scale triplet lifetimes, efficient intersystem crossing, and slow rates of nonradiative recombination. Here, a simple and scalable approach is demonstrated to activate long‐lived phosphorescence in a wide variety of molecules by suspending them in rigid polymer hosts and annealing them above the polymer's glass transition temperature. This process produces submicron aggregates of the chromophore, which suppresses intramolecular motion that leads to nonradiative recombination and minimizes triplet–triplet annihilation that quenches phosphorescence in larger aggregates. In some cases, evidence of excimer‐mediated intersystem crossing that enhances triplet generation in aggregated chromophores is found. In short, this approach circumvents the current design rules for long‐lived phosphors, which will streamline their discovery and development.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Mixed lipid bilayers enable enhanced stability and activity retention of Lipase A in low-pH environments

Lipase A (LipA) from Bacillus subtilis is a versatile and industrially relevant enzyme, but its activity is compromised under acidic conditions due to aggregation and deactivation. In this study, we investigated the use of mixed lipid bilayers to stabilize and improve activity retention of LipA at low pH. Attachment to lipid bilayers, particularly those containing cationic lipids, greatly enhanced the long-term stability of LipA in acidic conditions while also leading to improvements in activity. Tethering to cationic bilayers not only shifted the apparent pH activity profile toward more acidic conditions, but also significantly enhanced activity retention upon incubation at pH 6. Notably, this protective effect persisted even without direct tethering, indicating that reversible, non-covalent interactions with the bilayer surface are sufficient for long-term stability. Circular dichroism further revealed that the secondary structure of LipA was retained, while dynamic light scattering suggested that activity loss in solution was primarily due to aggregation of the native state. Together, these findings support a model in which lipid bilayers mitigate aggregation and stabilize LipA through transient interactions and electrostatic modulation of the local surface environment. Furthermore, this approach exemplifies a simple, tether-free strategy for enhancing enzyme performance in acidic or destabilizing conditions, with implications for biocatalysis, biosensing, and therapeutic delivery.

Biocatalysis↗
DOE OSTI2024

Coal-derived electrically conductive asphalt pavements for snow/ice melting: From laboratory to field

Timely removal of ice and snow from roads is critical to safe, fast, and uninterrupted transportation networks in cold regions. Constructing electrically conductive asphalt pavements to melt the ice and snow on the roads through resistive eating is an emerging alternative technology to traditional snow/ice removal approaches such as utilizing snowplow machines and deicing chemicals. Carbon-based fibers and fillers including carbon fiber and graphite have been widely reported to make electrically conductive hot mix asphalt mixtures for pavement snow/ice-melting applications. This study aimed to develop and demonstrate a novel type of electrically conductive asphalt pavements for snow/ice-melting, which utilizes electrically conductive cold mix asphalt (CMA) mixtures incorporating coal-derived carbon-based coke aggregate as resistive heating elements. Both laboratory experiments and field tests were conducted to investigate the electrical, mechanical, and thermal properties of such electrically conductive asphalt mixtures and pavements. The laboratory experiment results indicated that the electrically conductive CMA mixtures incorporating coke aggregate had sufficiently high electrical conductivity and satisfactory mechanical performance and the pavement prototype slab utilizing a thin layer of such CMA mixtures could successfully raise the pavement surface temperatures to 8.3–11.7 °C rom a low temperature of –5 °C with an input power density of 473 W/m 2 . The field test results showed that the full-scale coal-derived electrically conductive asphalt pavements were able to increase the pavement surface temperatures when electricity was applied, but the magnitude of temperature increase was highly dependent on the power density. Furthermore, it is promising to use coke aggregate to construct coal-derived electrically conductive asphalt pavements for snow/ice melting.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Structural Insight into a Sixteen Cyanine Dye Construct via Exciton–Exciton Annihilation

Molecular (dye) aggregates play a prominent role in light harvesting and are of interest in quantum information science; however, there are limited reports hat programmably assemble many (>4) dye aggregates featuring strong coupling and exciton delocalization. Using oligonucleotides with four Cy5s covalently linked in series along the phosphate backbone, we bring four, eight, and sixteen Cy5s in close proximity by assembling four-armed junctions. We elucidate their structure via gel electrophoresis and steady-state and transient optical spectroscopy. We find that Cy5 has a strong propensity to form tetramer clusters, where the exciton is delocalized over all four Cy5s, that the exciton is not delocalized beyond tetramer clusters in the eight and sixteen Cy5 constructs, and that the sixteen Cy5 construct may consist of pairs of tetramer clusters that are isolated from one another. Many-dye aggregates such as these may serve useful as antennae for their intense light absorption and spatially directed energy transfer.

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

Supramolecular Assembly of Lanthanide-Binding Tag Peptides for Aqueous Separation of Rare Earth Elements

Selective and eco-friendly separation and purification methods for rare earth elements (REEs) are necessary to meet the increasing demand for these valuable metals, which are extensively used in modern electronics and clean energy technologies. Mining feedstocks consist of REE mixtures as stable trivalent cations (Ln 3+ ) that are difficult to separate due to their identical charge and similar size. Lanthanide-binding tags (LBTs), peptide chelates that coordinate Ln 3+ in binding pockets, show promise as selective, high-affinity extractants. We demonstrate that the LBT variant LBTLLA 5– , designed for high selectivity for Tb 3+ , is an effective extractant, forming complexes with REEs in solution that subsequently organize into self-assembling structures rich in Ln 3+ . These structures condense into aggregates that can be separated, enabling an efficient, all-aqueous, eco-friendly separation process. The self-assembled structures are studied using dynamic light scattering, ζ-potential measurements, transmission electron microscopy, anomalous small-angle X-ray scattering, inductively coupled plasma optical emission spectroscopy, and ultraviolet–visible absorption spectroscopy, which confirm LBTLLA 5– peptide-REE ion binding and the further assembly of micron-scale structures rich in REEs. Molecular dynamics simulations reveal the interactions promoting aggregation as well as the integrity of the binding pocket upon self-assembly. We find that LBTLLA 5– :Ln 3+ complexes recruit excess cations within the macrostructures, and we demonstrate that aggregation and selective separation can be controlled by manipulating the metal-peptide ratio in solution. Furthermore, we demonstrate separation from equimolar mixtures of REE pairs Tb 3+ -Lu 3+ and Tb 3+ -La 3+ , supporting the application of LBT peptides as a platform for the selective separation of REEs.

LBT peptides↗
NASA NTRS2003

Physical association and functional interaction between beta1 integrin and CD98 on human T lymphocytes

CD98 is a cell surface protein previously characterized as a cell activation marker, an amino acid transporter, and has recently been implicated in integrin-related functions. Integrins are cell surface proteins, important for homotypic cell aggregation, cell adhesion, and coactivation of T lymphocytes. We have previously shown that the anti-CD98 mAb 80A10, when coimmobilized with anti-CD3 mAb OKT3, is able to mediate human T cell coactivation that is inhibited by anti-beta1 integrin specific mAb 18D3. These results indicated a functional association of CD98 and beta1 integrin signaling but left open the question of a physical association. We now show the induction of homotypic aggregation through CD98 among human T cells and this aggregation was inhibited by anti-beta1 integrin mAb. Therefore, CD98-dependent lymphocyte proliferation and adhesion may involve integrins. Competitive binding assays and fluorescence colocalization analysis suggested that CD98 and beta1 integrin were physically associated. Differential extraction techniques and immunoprecipitations provided the first evidence that the alpha4beta1 integrin and CD98 are specifically associated on human T lymphocytes.

NASA Discipline Cell Biology↗
NASA NTRS1998

Formation and differentiation of three-dimensional rat marrow stromal cell culture on microcarriers in a rotating-wall vessel

Using a high aspect ratio vessel (HARV), this study investigated the formation of 3-D rat marrow stromal cell culture on microcarriers and the expression of bone-related biochemical markers under conditions of simulated microgravity. In addition, it calculated the shear stresses imparted on the surface of microcarriers of different densities by the medium fluid in an HARV. Secondary rat marrow stromal cells were cultured on two types of microcarriers, Cytodex-3 beads and modified bioactive glass particles. Examination of cellular morphology by scanning electron microscopy revealed the presence of three-dimensional multicellular aggregates consisting of multiple cell-covered Cytodex-3 microcarriers bridged together. Mineralization was observed in the aggregates. Spherical cell-bead aggregates were observed in an HARV, while cell-bead assemblies were mostly loosely packed in a chain-like or branched structure in a cell bag. The expressions of alkaline phosphatase activity, collagen type I, and osteopontin were shown via the use of histochemical staining, immunolabeling, and confocal scanning electron microscopy. Using a numerical approach, it was found that at a given rotational speed and for a given culture medium, a larger density difference between the microcarrier and the culture medium (e.g., a modified bioactive glass particle) imparted a higher maximum shear stress on the microcarrier.

Dextrans↗
NASA NTRS2020

Observed Modulation of the Tropical Radiation Budget by Deep Convective Organization and Lower-Tropospheric Stability

This study analyses the observed monthly deseasonalized and detrended variability of the tropical radiation budget, and suggests that variations of the lower-tropospheric stability and of the spatial organization of deep convection both strongly contribute to this variability. Satellite observations show that on average over the tropical belt, when deep convection is more aggregated, the free troposphere is drier, the deep-convective cloud coverage is less extensive, and the emission of heat to space is increased; an enhanced aggregation of deep convection is thus associated with a radiative cooling of the tropics. An increase of the tropical-mean lower-tropospheric stability is also coincident with a radiative cooling of the tropics, primarily because it is associated with more marine low clouds and an enhanced reflection of solar radiation, although the free-tropospheric drying also contributes to the cooling. The contributions of convective aggregation and lower-tropospheric stability to the modulation of the radiation budget are complementary, largely independent of each other, and equally strong. Together, they account for more than sixty percent of the variance of the tropical radiation budget. Satellite observations are thus consistent with the suggestion from modeling studies that the spatial organization of deep convection substantially influences the radiative balance of the Earth. This emphasizes the importance of understanding the factors that control convective organization and lower-tropospheric stability variations, and the need to monitor their changes as the climate warms.

convective aggregation↗
DOE OSTI2024

Valuing EV Managed Charging for Bulk Power Systems

When and where electric vehicle (EV) charging occurs has significant implications for power systems supporting widespread EV adoption, especially with high shares of wind and solar generation. This study extends previous works by leveraging detailed simulation models for EV adoption, EV use, EV charging, and bulk power system operations, and by linking them with methods for describing charging flexibility at both the individual vehicle and aggregate levels. This technical potential study focuses on how the value of EV managed charging (EVMC) changes depending on charging flexibility type (within-charging session or within-week scheduling), dispatch mechanism (direct load control or one of several price-based mechanisms), and managed charging participation rate. We show that naively aggregating EV charging flexibility from individual vehicles into megawatt-scale resources grossly overestimates the flexibility of the fleet, because such aggregate models can unrealistically pair, e.g., one already-fully-charged vehicle's ability to increase load with another already-charging vehicle's ability to accept more charge, effectively requesting a charging rate that is infeasible for the latter vehicle. We find per-vehicle bulk system value is highest at low participation rates for all dispatch mechanisms. Factoring in production cost savings, avoided firm capacity savings, and combustion-related power sector emissions savings, we estimate the value of EVMC at low participation rates (5%) to be $33/vehicle-year to $69/vehicle-yr for within-session charging flexibility and $40/vehicle-yr to $120/vehicle-yr for within-week charging flexibility in an envisioned 2038 New England power system and monetary value reported in 2016 U.S. dollars. At 100% participation, per-vehicle value declines to $25/vehicle-yr to $31/vehicle-yr for within-session charging flexibility and to $29/vehicle-yr to $36/vehicle-yr for within-week charging flexibility; however, 100% participation yields the highest total system savings.

ADVANCED PROPULSION SYSTEMS↗
DOE OSTI2025

Lyotropic Liquid Crystal Mediated Assembly of Donor Polymers Enhances Efficiency and Stability of Blade-Coated Organic Solar Cells

Conjugated polymers can undergo complex, concentration-dependent self-assembly during solution processing, yet little is known about its impact on film morphology and device performance of organic solar cells. Herein, lyotropic liquid crystal (LLC) mediated assembly across multiple conjugated polymers is reported, which generally gives rise to improved device performance of blade-coated non-fullerene bulk heterojunction solar cells. Using D18 as a model system, the formation mechanism of LLC is unveiled employing solution X-ray scattering and microscopic imaging tools: D18 first aggregates into semicrystalline nanofibers, then assemble into achiral nematic LLC which goes through symmetry breaking to yield a chiral twist-bent LLC. The assembly pathway is driven by increasing solution concentration – a common driving force during evaporative assembly relevant to scalable manufacturing. This assembly pathway can be largely modulated by coating regimes to give 1) lyotropic liquid crystalline assembly in the evaporation regime and 2) random fiber aggregation pathway in the Landau–Levich regime. The chiral liquid crystalline assembly pathway resulted in films with crystallinity 2.63 times that of films from the random fiber aggregation pathway, significantly enhancing the T80 lifetime by 50-fold. The generality of LLC-mediated assembly and enhanced device performance is further validated using polythiophene and quinoxaline-based donor polymers.

14 SOLAR ENERGY↗
DOE OSTI2024

Regulation of Side‐Chain Symmetry for Delaying Triplet Formation and Suppressing Non‐Radiative Loss in Organic Solar Cells

Abstract The structural revolutions of non‐fullerene acceptors (NFAs) have driven continuous efficiency breakthroughs in organic solar cells (OSCs). Rational regulation of NFA structures toward efficient exciton dissociation and mitigated non‐radiative recombination is pivotal for OSCs. The incorporation of asymmetric side chains on NFAs can often achieve these goals by inducing a desirable aggregate state. However, it lacks the studies to directly correlate the side‐chain symmetry of NFAs with the exciton delocalization and triplet dynamics in OSCs. Herein, The influence of structural symmetry on the aggregate properties is systematically investigated and exciton/charge dynamics based on two developed biaxial‐conjugated NFAs with varied side‐chain symmetry. The symmetric NFA having diverse molecular packing orientations can form multiple charge transfer channels in its blend with polymer donor, which cannot be found in that comprising the asymmetric ones. Moreover, a slower rate and lower ratio of the spin‐triplet state are formed in the blend of symmetric NFA, resulting in a much lower non‐radiative voltage loss in corresponding OSCs. This study reveals the distinct advantages of symmetric NFAs in both aggregate properties and exciton/charge dynamics over those of asymmetric ones, paving the way for developing high‐performance OSCs using easier‐to‐prepare, low‐cost symmetric materials.

Chemistry↗
DOE OSTI2025

Environmental controls on the kinetics of iron-sulfur cluster nucleation and nanoparticle formation

Anoxic, sulfidic conditions have been prevalent since the early Proterozoic and favor aqueous iron-sulfur (FeS aq ) clusters as a major fraction of the soluble, reduced iron and sulfur pool. FeS aq cluster formation and nucleation is driven by the high affinity between ferrous iron (Fe(II)) and sulfide (HS − ), ultimately yielding particles that precipitate as iron sulfide minerals. FeS aq clusters were recently shown to be bioavailable sources of iron and sulfur for a variety of anaerobes, yet little is known of the factors that influence the kinetics of their formation and nucleation. Here we apply computational and spectroscopic approaches to investigate the dynamics of FeS aq nucleation, cluster growth, precipitation, and redissolution as a function of Fe(II)/HS − concentration, temperature, and pH. Experiments were conducted under excess HS − to mimic euxinic conditions common to contemporary anaerobic aquatic ecosystems and those of the Proterozoic. Density functional theory calculations reveal the key role of water oxygen-iron interactions in stabilizing small FeS aq clusters and promoting solubility. Dynamic light scattering revealed a concentration-dependent increase in the kinetics of FeS aq nucleation and cluster aggregation. Increasing temperature promoted FeS aq cluster nucleation and aggregation while also enhancing dissolution. Alkaline pH also promoted FeS aq nucleation and cluster aggregation. At 25 °C, pH 7.0, and at reactant concentrations of 30 µM, FeS aq clusters < 10 nm in diameter remained in solution for > 2 h. These results underscore the importance of temperature, pH, and reactant concentration in the kinetics of FeS aq nucleation and cluster growth that, in turn, influence their bioavailability in anaerobic ecosystems.

Aquatic ecosystems↗