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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 91 records · Page 5
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Tetrameric self-assembling of water-lean solvents enables carbamate anhydride-based CO2 capture chemistry

Abstract Carbon capture, utilization and storage is a key yet cost-intensive technology for the fight against climate change. Single-component water-lean solvents have emerged as promising materials for post-combustion CO 2 capture, but little is known regarding their mechanism of action. Here we present a combined experimental and modelling study of single-component water-lean solvents, and we find that CO 2 capture is accompanied by the self-assembly of reverse-micelle-like tetrameric clusters in solution. This spontaneous aggregation leads to stepwise cooperative capture phenomena with highly contrasting mechanistic and thermodynamic features. The emergence of well-defined supramolecular architectures displaying a hydrogen-bonded internal core, reminiscent of enzymatic active sites, enables the formation of CO 2 -containing molecular species such as carbamic acid, carbamic anhydride and alkoxy carbamic anhydrides. This system extends the scope of adducts and mechanisms observed during carbon capture. It opens the way to materials with a higher CO 2 storage capacity and provides a means for carbamates to potentially act as initiators for future oligomerization or polymerization of CO 2 .

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Probing single-chain conformation and its impact on the optoelectronic properties of donor–accepter conjugated polymers

The chain conformation of donor–acceptor conjugated polymers (D–A CPs) is critical to their optical and electronic properties. However, probing the conformation of D–A CPs (e.g., persistence length and contour length) at a single-chain level is challenging due to the formation of aggregates in dilute solution, even in a good solvent. In this work, we studied the chain conformation and corresponding optical spectra for high-performance D–A CPs in the single-chain state by multimodal variable-temperature scattering and spectroscopy techniques, as well as by molecular dynamics simulations. Here we found a critical role of the side-chain length and branch point in the persistence length and optical absorption due to steric effects. Hence, it is important to consider both the chain rigidity and coplanarity of the polymer backbone to achieve desirable optoelectronic properties. Our findings bridge the fundamental knowledge gaps to design new CPs with desired optoelectronic properties via molecular engineering for next-generation electronic devices.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Sampling on NISQ Devices: "Who’s the Fairest One of All?"

Modern NISQ devices are subject to a variety of biases and sources of noise that degrade the solution quality of computations carried out on these devices. A natural question that arises in the NISQ era, is how fairly do these devices sample ground state solutions. To this end, we run five fair sampling problems (each with at least three ground state solutions) that are based both on quantum annealing and, on the Grover Mixer, -QAOA algorithm for gate-based NISQ hardware. In particular, we use seven IBM Q devices, the Aspen-9 Rigetti device, the IonQ device, and three D-Wave quantum annealers. For each of the fair sampling problems, we measure the ground state probability, the relative fairness of the frequency of each ground state solution with respect to the other ground state solutions, and the aggregate error as given by each hardware provider. Overall, our results show that NISQ devices do not achieve fair sampling yet. Furthermore, we also observe differences in the software stack with a particular focus on compilation techniques that illustrate what work will still need to be done to achieve a seamless integration of frontend (i.e., quantum circuit description) and backend compilation.

Computer Science↗
NASA NTRS1981

Terrestrial evolution of polymerization of amino acids - Heat to ATP

Sets of amino acids containing sufficient trifunctional monomer are thermally polymerized at temperatures such as 65 deg; the amino acids order themselves. Various polymers have diverse catalytic activities. The polymers aggregate, in aqueous solution, to cell-like structures having those activities plus emergent properties, e.g. proliferatability. Polyamino acids containing sufficient lysine catalyze conversion of free amino acids, by ATP, to small peptides and a high molecular weight fraction. The lysine-rich proteinoid is active in solution, within suspensions of cell-like particles, or in other particles composed of lysine-rich proteinoid and homopolyribonucleotide. Selectivities are observed. An archaic polyamino acid prelude to coded protein synthesis is indicated.

Fox, S. W.↗
NASA NTRS1988

Semi-microdroplet assay for cell adhesion molecules

A new cell-to-cell adhesion assay was devised. Using dissociated embryos of the sea urchin, this procedure involves rotating a 0.100 ml suspension of single cells with 0.100 ml of the solution to be tested in the bulb portion of a transfer pipet with the tip removed. After 1 hour of rotation at 60 rpm at 15 C, the contents of each bulb were transferred into individual wells of a 96 well flat bottom plate. After the plate was incubated for 1 hour at 15 C, black and white photographs were taken with a 35 mm camera attached to an inverted photomicroscope. Examining a proof sheet of the negatives directly allowed a rapid evaluation of suspected cell adhesion promoting factors. A ranking system was used to evaluate all samples. The assay was tested by examining the effect of specific solutions on the aggregation of single cells obtained from dissociated 23 hour embryos.

Tawa, Lawrence Shinzo↗
NASA NTRS1994

The effects of temperature and NaCl concentration on tetragonal lysozyme face growth rates

Measurements were made of the (110) and (101) face growth rates of the tetragonal form of hen egg white lysozyme at 0.1M sodium acetate buffer, pH 4.0, from 4 to 22 C and with 3.0%, 5.0%, and 7.0% NaCl used as the precipitating salt. The data were collected at supersaturation ratios ranging from approximately 4 to approximately 63. Both decreasing temperature and increasing salt concentrations shifted plots of the growth rate versus C/C(sat) to the right, i.e. higher supersaturations were required for comparable growth rates. The observed trends in the growth data are counter to those expected from the solubility data. If tetragonal lysozyme crystal growth is by addition of ordered aggregates from the solution, then the observed growth data could be explained as a result of the effects of lowered temperature and increased salt concentration on the kinetics and equilibrium processes governing protein-protein interactions in solution. The data indicate that temperature would be a more tractable means of controlling the growth rate for tetragonal lysozyme crystals contrary to the usual practice in, e.g., vapor diffusion protein crystal growth, where both the precipitant and protein concentrations are simultaneously increased. However, the available range for control is dependent upon the protein concentration, with the greatest growth rate control being at the lower concentration.

Forsythe, Elizabeth↗
NASA NTRS1998

Growth of (101) Faces of Tetragonal Lysozyme Crystals: Measured Growth Rate Trends

Earlier extensive measurements of the growth rates of the (110) face of tetragonal lysozyme crystals had shown unexpected dependencies on the supersaturation. In this study similar growth rate measurements were done for the (101) faces of the crystals. The data show a similar dependence on the supersaturation, becoming appreciable only at high supersaturations, reaching a maximum value and then decreasing. As reported in earlier studies, the (101) growth rates are larger at low supersaturations than the (110) growth rates at the same conditions, and smaller at high supersaturations. These trends suggest that the growth mechanism of the (101) is similar to that of the (110) face, involving the addition of lysozyme aggregates formed in solution, but with a growth unit smaller than that of the (110) face.

Forsythe, Elizabeth L.↗
DOE OSTI2024

Colloidal Stability of PFSA-Ionomer Dispersions. Part I. Single-Ion Electrostatic Interaction Potential Energies

Charged colloidal particles neutralized by a single counterion are increasingly important for many emerging technologies. Attention here is paid specifically to hydrogen fuel cells and water electrolyzers whose catalyst layers are manufactured from a perfluorinated sulfonic acid polymer (PFSA) suspended in aqueous/alcohol solutions. Partially dissolved PFSA aggregates, known collectively as ionomers, are stabilized by the electrostatic repulsion of overlapping diffuse double layers consisting of only protons dissociated from the suspended polymer. We denote such double layers containing no added electrolyte as "single ion". Size-distribution predictions build upon interparticle interaction potential energies from the Derjaguin-Landau-Verwey-Overbeek (DLVO) formalism. However, when only a single counterion is present in solution, classical DLVO electrostatic potential energies no longer apply. Accordingly, here a new formulation is proposed to describe how single-counterion diffuse double layers interact in colloidal suspensions. Part II (Srivastav, H.; Weber, A. Z.; Radke, C. J. Langmuir 2024 DOI: 10.1021/acs.langmuir.3c03904) of this contribution uses the new single-ion interaction energies to predict aggregated size distributions and the resulting solution pH of PFSA in mixtures of n-propanol and water. A single-counterion diffuse layer cannot reach an electrically neutral concentration far from a charged particle. Consequently, nowhere in the dispersion is the solvent neutral, and the diffuse layer emanating from one particle always experiences the presence of other particles (or walls). Thus, in addition to an intervening interparticle repulsive force, a backside osmotic force is always present. With this new construction, we establish that single-ion repulsive pair interaction energies are much larger than those of classical DLVO electrostatic potentials. The proposed single-ion electrostatic pair potential governs dramatic new dispersion behavior, including dispersions that are stable at a low volume fraction but unstable at a high volume fraction and finite volume-fraction dispersions that are unstable with fine particles but stable with coarse particles. Finally, the proposed single-counterion electrostatic pair potential provides a general expression for predicting colloidal behavior for any charged particle dispersion in ionizing solvents with no added electrolyte.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Predicting Outcomes of Nanoparticle Attachment by Connecting Atomistic, Interfacial, Particle, and Aggregate Scales

Predicting nanoparticle aggregation and attachment phenomena requires a rigorous understanding of the interplay among crystal structure, particle morphology, surface chemistry, solution conditions, and interparticle forces, yet no comprehensive picture exists. We used an integrated suite of experimental, theoretical, and simulation methods to resolve the effect of solution pH on the aggregation of boehmite nanoplatelets, a case study with important implications for the environmental management of legacy nuclear waste. Real-time observations showed that the particles attach preferentially along the (010) planes at pH 8.5 and the (101) planes at pH 11. To rationalize these results, we established the connection between key physicochemical phenomena across the relevant length scales. Starting from molecular-scale simulations of surface hydroxyl reactivity, we developed an interfacial-scale model of the corresponding electrostatic potentials, with subsequent particle-scale calculations of the resulting driving forces allowing successful prediction of the attachment modes. Finally, we scaled these phenomena to understand the collective structure at the aggregate-scale . Here, our results indicate that facet-specific differences in surface chemistry produce heterogeneous surface charge distributions that are coupled to particle anisotropy and shape-dependent hydrodynamic forces, to play a key role in controlling aggregation behavior.

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

A Solvatochromic Near Infrared Fluorophore Sensitive to the Full Amyloid Beta Aggregation Pathway

Alzheimer's disease has long been associated with the aggregation of amyloid beta peptides (Aβ42) into macroscale plaques, although specific neurodegenerative agents have not been definitively identified. Much evidence has pointed to the soluble nanoscale oligomers that form early in the Aβ42 aggregation pathway, but there is little understanding of these structures, their mechanisms of formation, or how they grow into plaques. Here, we show that a solvatochromic fluorophore with near-infrared (NIR) emission can track synthetic Aβ42 aggregation through environment-sensitive spectral shifts from the earliest time points through plaque formation. This azide-functionalized phosphine oxide azetidine rhodol (Phazr-N3) shows large polarity-dependent changes in fluorescence emission, with maxima shifting from 630 nm in toluene to 703 nm in aqueous buffer, and a maximum quantum yield of 62%. Upon induction of Aβ42 aggregation, we observe immediate solvatochromic changes in Phazr-N3 fluorescence, with multiple apparent phases over 12 h, and which culminate before the onset of any major fluorescence changes of conformation-specific aggregation fluorophore thioflavin T. Solution anisotropy measurements show a low micromolar affinity of Phazr-N3 for disordered, free Aβ42 in solution, and real-time measurements are consistent with rapid liquid-liquid phase separation and slow dehydration of the growing aggregate. Spectral imaging of synthetic plaques stained in the presence of live cells and lipid-binding protein albumin shows over 4000-fold Phazr-N3 fluorescence intensity above background under no-wash conditions, and over 100-fold intensity above coplated microglial cells or a large excess of albumin. This use of a solvatochromic probe with structure-independent binding to free Aβ42 offers real-time, minimally invasive insight into the full Aβ42 aggregation pathway.

Wang, Zeming↗
NASA NTRS2000

Size Exclusion Chromatography Studies of the Initial Self-Association Steps of Chicken Egg White Lysozyme Nucleation

Nucleation is one of the least understood aspects of crystallogenesis. In the case of macromolecule nucleation, this understanding is further hampered by uncertainty over what precisely is being discussed. We define the process of solute self-association (aggregation, oligomerization, interaction, clustering, etc.) whereby n-mers (n > or = 2) having a crystallographic or nascent crystallographic arrangement leading to the critical nucleus reversibly form in the solution, to be part of the nucleation process. This reversible self-association process is a fundamental part of the nucleation process, and occurs as a function of the solute concentration. In the case of chicken egg white lysozyme, a considerable body of experimental evidence leads us to the conclusion that it also forms the crystal growth units. Size exclusion chromatography is a simple and direct method for determining the equilibrium constants for the self-association process. A Pharmacia FPLC system was used to provide accurate solution flow rates. The column, injection valve, and sample loop were all mounted within a temperature-controlled chamber. Chromatographically re-purified lysozyme was first dialyzed against the column equilibration buffer, with injection onto the column after several hours pre-incubation at the running temperature. Preliminary experiments, were carried out using a Toyopearl HW-50F column (1 x 50cm), equilibrated with 0.1 M sodium acetate, 5% sodium chloride, pH 4.6, at 15C. Protein concentrations from 0.1 to 4 mg/ml were employed (C(sub sat) = 1.2 mg/ml). The data from several different protein preparations consistently shows a progressively decreasing elution volume with increasing protein concentration, indicating that reversible self-association is occurring. The dotted line indicates the monomeric lysozyme elution volume. However, lysozyme interacts with the column matrix in these experiments, which complicates data analysis.Accordingly, we are testing silica-based HPLC columns in an effort to eliminate this problem and substantially reduce the column volume and experimental run time. The results and data analysis from these and subsequent experiments will be presented.

Ewing, Felecia↗
NASA NTRS1998

Modeling the Growth Rates of Tetragonal Lysozyme Crystal Faces

The measured macroscopic growth rates of the (110) and (101) faces of tetragonal lysozyme show an unexpectedly complex dependence on the supersaturation. The growth rates decay asymptotically to zero when the supersaturation is lowered to zero and increase rapidly when the supersaturation is increased. When supersaturations are increased still further the growth rates attain a maximum before starting to decrease. However, growth of these crystals is known to proceed by the classical dislocation and 2D nucleation growth mechanisms. This anomaly can be explained if growth is assumed to occur not by monomer units but by lysozyme aggregates. Analysis of the molecular packing of these crystals revealed that they were constructed of strongly bonded 4(sub 3) helices, while weaker bonds were responsible for binding the helices to each other. It follows that during crystal growth the stronger bonds are formed before the weaker ones. Thus, the growth of these crystals could be viewed as a two step process: aggregate growth units corresponding to the 4(sub 3) helix are first formed in the bulk solution by stronger intermolecular bonds and then attached to the crystal face by weaker bonds on dislocation hillocks or 2D islands. This will lead to a distribution of aggregates in the solution with monomers and lower order aggregates being predominant at low supersaturations and higher order aggregates being predominant at high supersaturations. If the crystal grows mostly by higher order aggregates, such as tetramers and octamers, it would explain the anomalous dependence of the growth rates on the supersaturation. Besides the analysis of molecular packing, a comprehensive analysis of the measured (110) and (101) growth rates was also undertaken in this study. The distribution of aggregates in lysozyme nutrient solutions at various solution conditions were determined from reversible aggregation reactions at equilibrium. The supersaturation was defined for each aggregate species with respect to its concentration at saturation in order to apply growth rate models to this process. The measured growth rates were then compared with the predicted ones from several dislocation and 2D nucleation growth models, employing tetramer and octamer growth units in polydisperse solutions and monomer units in monodisperse solutions. For the (110) face, the calculations consistently showed that the measured growth rates followed the expected model relations with octamer growth units. For the (101) face, it is not possible to obtain a clear agreement between the predicted and measured growth rates for a single growth unit as done for the (110) face. However, the calculations do indicate that the average size of the growth unit is between a tetramer and an octamer. This suggests that tetramers, octamers and other intermediate size growth units all participate in the growth process for this face. These calculations show that it is possible to model the macroscopic protein crystal growth rates if the molecular level processes can be account for, particularly protein aggregation processes in the bulk solution. Our recent investigations of tetragonal lysozyme crystals employing high resolution atomic force microscopy scans have further confirmed the growth of these crystals by aggregate growth units corresponding to 4(sub 3) helices.

Li, Meirong↗
DOE OSTI2022

Beyond Local Solvation Structure: Nanometric Aggregates in Battery Electrolytes and their Effect on Electrolyte Properties

Electrolytes are an essential component of all electrochemical storage and conversion devices, such as batteries. In the history of battery development, the complex nature of electrolytes has often been a bottleneck. Fundamental knowledge of electrolyte systems encompasses elucidation of structure-property relationships of the solution species. Recently, nanometric aggregates have been observed in several classes of electrolytes, including super-concentrated, redox-flow, multivalent, polymer, and ionic liquid-based electrolytes. Compared with the well-studied local solvation structures such as contact ion pairs and solvent-separated ions, these aggregates impose unique effects on the ion distribution and transport both within bulk electrolytes and at electrode/electrolyte interfaces. This Perspective highlights the discovery of the aggregates in various battery electrolytes and their impact on electrolyte properties. We also present an outlook for future studies of this emerging field of nanometric aggregates and the need for the development of new experimental and computational tools to study their properties.

Yu, Zhou↗
DOE OSTI2023

Solution Structure and Hydration Forces between Mica and Hydrophilic Versus Hydrophobic Surfaces

Solid-liquid interfaces are central to a range of interesting phenomena including catalysis, heterogeneous nucleation, water desalination, and biomolecular assembly. While three-dimensional Fast Force Mapping (3D FFM) has emerged as a technique for resolving interfacial solution structure at the molecular scale, key challenges for data interpretation persist, most notably regarding the influence of the probe on the measured structure. Using the mica-water system as a case study, we investigate the effect of hydrophilic and hydrophobic probes on interfacial solution structure measured by 3D FFM. Data from hydrophilic silicon-based probes are in good agreement with molecular dynamics simulations, wherein the innermost water molecules adsorb preferentially at the surface ditrigonal cavity sites followed by two subsequent hydration layers. In contrast, the hydrophobic carbon-based probes detect vertical oscillatory features, but do not show lateral patterning that matches the underlying mica lattice. At high ionic strength, up to six of these oscillatory features are observed extending 2 nm into the solution phase with an average spacing of 0.29 ± (0.04) nm. Further, we also determine that the repulsive hydration force between mica and the hydrophilic probe depends on the nature and concentration of ions in solution. Specifically, solutions with stronger ion-water and ion-ion interactions increase the interfacial viscosity, which results in a stronger repulsive hydration force as the probe approaches the surface. Based on these observations, we present a scheme for controlling the outcomes of particle attachment and aggregation by varying the solution conditions to tune the hydration force.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

In-Use Interfacial Stability of Monoclonal Antibody Formulations Diluted in Saline i.v. Bags

The use of monoclonal antibodies (mAbs) for the treatment of a variety of diseases is rapidly growing each year. Many mAbs are administered intravenously using i.v. bags containing 0.9% NaCl (normal saline). We studied the aggregation propensity of these antibody solutions in saline and compared it with a low ionic strength formulation buffer. Furthermore, the mAb studied in this work is prone to aggregate, and is known to form a viscoelastic network at the air-solution interface. We observed that this interfacial elasticity increased when formulated in saline. In the bulk, the mAbs exhibited a tendency to self-associate that was higher in saline. We also studied the aggregation of the mAbs in the presence of polysorbate-20, typically added to formulations to mitigate interfacial aggregation. We observed that with surfactants, the presence of salt in the buffer led to a greater mAb adsorption at the interface and resulted in the formation of more particulate aggregates. Our results show that the addition of salt to the buffer led to differences in the interfacial aggregation in mAb formulations, showing that stress studies used to screen for mAb aggregation intended for i.v. administration should be performed in conditions representative of their intended route of administration.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2020

Selective Sampling for Sensor Type Classification in Buildings

A key barrier to applying any smart technology to a building is the requirement of locating and connecting to the necessary resources among the thousands of sensing and control points, i.e., the metadata mapping problem. Existing solutions depend on exhaustive manual annotation of sensor metadata --- a laborious, costly, and hardly scalable process. To reduce the amount of manual effort required, this paper presents a multi-oracle selective sampling framework to leverage noisy labels from information sources with unknown reliability such as existing buildings, which we refer to as weak oracles, for metadata mapping. This framework involves an interactive process, where a small set of sensor instances are progressively selected and labeled for it to learn how to aggregate the noisy labels as well as to predict sensor types. Two key challenges arise in designing the framework, namely, weak oracle reliability estimation and instance selection for querying. To address the first challenge, we develop a clustering-based approach for weak oracle reliability estimation to capitalize on the observation that weak oracles perform differently in different groups of instances. For the second challenge, we propose a disagreement-based query selection strategy to combine the potential effect of a labeled instance on both reducing classifier uncertainty and improving the quality of label aggregation. We evaluate our solution on a large collection of real-world building sensor data from 5 buildings with more than 11,000 sensors of 18 different types. The experiment results validate the effectiveness of our solution, which outperforms a set of state-of-the-art baselines.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2023

Observing ion diffusion and reciprocating hopping motion in water

When an ionic crystal dissolves in solvent, the positive and negative ions associated with solvent molecules release from the crystal. However, the existing form, interaction, and dynamics of ions in real solution are poorly understood because of the substantial experimental challenge. We observed the diffusion and aggregation of polyoxometalate (POM) ions in water by using liquid phase transmission electron microscopy. Real-time observation reveals an unexpected local reciprocating hopping motion of the ions in water, which may be caused by the short-range polymerized bridge of water molecules. We find that ion oligomers, existing as highly active clusters, undergo frequent splitting, aggregation, and rearrangement in dilute solution. The formation and dissociation of ion oligomers indicate a weak counterion-mediated interaction. Furthermore, POM ions with tetrahedral geometry show directional interaction compared with spherical ions, which presents structure-dependent dynamics.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Point Sensor Networks Struggle to Detect and Quantify Short Controlled Releases at Oil and Gas Sites

This study evaluated multiple commercially available continuous monitoring (CM) point sensor network (PSN) solutions under single-blind controlled release testing conducted at operational upstream and midstream oil and natural gas (O&G) sites. During releases, PSNs reported site-level emission rate estimates of 0 kg/h between 38 and 86% of the time. When non-zero site-level emission rate estimates were provided, no linear correlation between the release rate and the reported emission rate estimate was observed. The average, aggregated across all PSN solutions during releases, shows 5% of the mixing ratio readings at downwind sensors were greater than the site’s baseline plus two standard deviations. Four of seven total PSN solutions tested during this field campaign provided site-level emission rate estimates with the site average relative error ranging from −100% to 24% for solution D, −100% to −43% for solution E, −25% for solution F (solution F was only at one site), and −99% to 430% for solution G, with an overall average of −29% across all sites and solutions. Of all the individual site-level emission rate estimates, only 11% were within ±2.5 kg/h of the study team’s best estimate of site-level emissions at the time of the releases.

42 ENGINEERING↗