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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 1,441 records · Page 80
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Phenotypic and functional characterization of corneal endothelial cells during in vitro expansion

The advent of cell culture-based methods for the establishment and expansion of human corneal endothelial cells (CEnC) has provided a source of transplantable corneal endothelium, with a significant potential to challenge the one donor-one recipient paradigm. However, concerns over cell identity remain, and a comprehensive characterization of the cultured CEnC across serial passages has not been performed. To this end, we compared two established CEnC culture methods by assessing the transcriptomic changes that occur during in vitro expansion. In confluent monolayers, low mitogenic culture conditions preserved corneal endothelial cell state identity better than culture in high mitogenic conditions. Expansion by continuous passaging induced replicative cell senescence. Transcriptomic analysis of the senescent phenotype identified a cell senescence signature distinct for CEnC. We identified activation of both classic and new cell signaling pathways that may be targeted to prevent senescence, a significant barrier to realizing the potential clinical utility of in vitro expansion.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Enhanced terrestrial Fe(II) mobilization identified through a novel mechanism of microbially driven cave formation in Fe(III)-rich rocks

Most cave formation requires mass separation from a host rock in a process that operates outward from permeable pathways to create the cave void. Given the poor solubility of Fe(III) phases, such processes are insufficient to account for the significant iron formation caves (IFCs) seen in Brazilian banded iron formations (BIF) and associated rock. Here in this study we demonstrate that microbially-mediated reductive Fe(III) dissolution is solubilizing the poorly soluble Fe(III) phases to soluble Fe(II) in the anoxic zone behind cave walls. The resultant Fe(III)-depleted material (termed sub muros) is unable to maintain the structural integrity of the walls and repeated rounds of wall collapse lead to formation of the cave void in an active, measurable process. This mechanism may move significant quantities of Fe(II) into ground water and may help to explain the mechanism of BIF dissolution and REE enrichment in the generation of canga. The role of Fe(III) reducing microorganism and mass separation behind the walls (outward-in, rather than inward-out) is not only a novel mechanism of speleogenesis, but it also may identify a previously overlooked source of continental Fe that may have contributed to Archaean BIF formation.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

High flux novel polymeric membrane for renal applications

Biocompatibility and the ability to mediate the appropriate flux of ions, urea, and uremic toxins between blood and dialysate components are key parameters for membranes used in dialysis. Oxone-mediated TEMPO-oxidized cellulose nanomaterials have been demonstrated to be excellent additives in the production and tunability of ultrafiltration and dialysis membranes. In the present study, nanocellulose ionic liquid membranes (NC-ILMs) were tested in vitro and ex vivo. An increase in flux of up to two orders of magnitude was observed with increased rejection (about 99.6%) of key proteins compared to that of polysulfone (PSf) and other commercial membranes. NC-ILMs have a sharper molecular weight cut-off than other phase inversion polymeric membranes, allowing for high throughput of urea and a uremic toxin surrogate and limited passage of proteins in dialysis applications. Superior anti-fouling properties were also observed for the NC-ILMs, including a > 5-h operation time with no systemic anticoagulation in blood samples. Finally, NC-ILMs were found to be biocompatible in rat ultrafiltration and dialysis experiments, indicating their potential clinical utility in dialysis and other blood filtration applications. These superior properties may allow for a new class of membranes for use in a wide variety of industrial applications, including the treatment of patients suffering from renal disease.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

High dimensional predictions of suicide risk in 4.2 million US Veterans using ensemble transfer learning

We present an ensemble transfer learning method to predict suicide from Veterans Affairs (VA) electronic medical records (EMR). A diverse set of base models was trained to predict a binary outcome constructed from reported suicide, suicide attempt, and overdose diagnoses with varying choices of study design and prediction methodology. Each model used twenty cross-sectional and 190 longitudinal variables observed in eight time intervals covering 7.5 years prior to the time of prediction. Ensembles of seven base models were created and fine-tuned with ten variables expected to change with study design and outcome definition in order to predict suicide and combined outcome in a prospective cohort. The ensemble models achieved c-statistics of 0.73 on 2-year suicide risk and 0.83 on the combined outcome when predicting on a prospective cohort of ~4.2 M veterans. The ensembles rely on nonlinear base models trained using a matched retrospective nested case-control (Rcc) study cohort and show good calibration across a diversity of subgroups, including risk strata, age, sex, race, and level of healthcare utilization. In addition, a linear Rcc base model provided a rich set of biological predictors, including indicators of suicide, substance use disorder, mental health diagnoses and treatments, hypoxia and vascular damage, and demographics. Similar content being viewed by others

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Effect of cathode on crosstalk in Si-based lithium-ion cells

Crosstalk between the cathode and the anode in Li-ion batteries has a great impact on performance, safety and cycle lifetime. However, a systematic investigation of crosstalk behavior in silicon (Si)-based cells with various cathode materials has not been reported. We investigated the crosstalk behavior of a Si anode coupled with one of the following cathodes—LiCoO 2 (LCO), LiNi 0.5 Mn 0.3 Co 0.2 (NMC532), and LiFePO 4 (LFP)—in a full cell. For each electrochemical couple, we compared electrolyte decomposition products, solid electrolyte interphase (SEI) chemistry, and degradation mechanisms during cycling. From a very early stage of cycling, each couple showed different crosstalk behavior; different electrolyte decomposition products and SEI chemistry on the Si anodes were seen. Specifically, the formation and growth mechanism of Si SEI differ depending on cathode materials. For the LFP system, the Si SEI rich in LiF and inorganic species, which is stable and robust. It forms at an early stage of cycle. As a result, the SEI of Si from the LFP system well tolerates SEI breakage due to mechanical changes of Si and suppresses Li loss, resulting in stable cycle life.

25 ENERGY STORAGE↗
DOE OSTI2022

Co-intercalation-free ether electrolytes for graphitic anodes in lithium-ion batteries

Carbonate-based electrolytes are widely used in Li-ion batteries but are limited by a small operating temperature window and poor cycling with silicon-containing graphitic anodes. The lack of non-carbonate electrolyte alternatives such as ether-based electrolytes is due to undesired solvent co-intercalation that occurs with graphitic anodes. Here, we show that fluoroethers are the first class of ether solvents to intrinsically support reversible lithium-ion intercalation into graphite without solvent co-intercalation at conventional salt concentrations. In full cells using a graphite anode, they enable 10-fold higher energy densities compared to conventional ethers, and better thermal stability over carbonate electrolytes (operation up to 60 °C) by producing a robust solvent-derived solid electrolyte interphase (SEI). As single-solvent–single-salt electrolytes, they remarkably outperform carbonate electrolytes with fluoroethylene carbonate (FEC) and vinylene carbonate (VC) additives when cycled with graphite–silicon composite anodes. In conclusion, our molecular design strategy opens a new class of electrolytes that can enable next generation Li-ion batteries with higher energy density and a wider working temperature window.

25 ENERGY STORAGE↗
DOE OSTI2022

Improving LiNiO 2 cathode performance through particle design and optimization

We report to enable further development of Ni-rich LiNi x Mn y Co 1-x-y O 2 (NMC, x ≥ 0.9) cathodes for commercial applications, fundamental understanding of the synthesis–property–performance relationships in the LiNiO 2 (LNO) parent phase is essential. In the present study, we report synthesis approaches to produce well-formed, similar-sized single-crystal LiNiO 2 (SC-LNO) with different shapes and dominating surface facets, and reveal the dependence of cathode rate performance and cycling stability on particle morphology and surface. While octahedron-shaped SC-LNO with the (012) surface shows better rate capability and improved ability in utilizing the kinetically slow anodic process in the 3.5 V region, cubic-shaped SC-LNO with the (104) surface delivers superior cycling stability, especially upon cycling at a high upper cutoff voltage of 4.6 V. Improvement in cycling stability is correlated with reduced surface reconstruction and preferential LiF formation through the interaction with the electrolyte on the (104) surface. Our study not only demonstrates the importance of particle morphology and surface design, it also provides key insights into desirable material properties for developing future LNO-based cathode materials with better performance.

25 ENERGY STORAGE↗
DOE OSTI2023

Stability of Kuramoto networks subject to large and small fluctuations from heterogeneous and spatially correlated noise

Oscillatory networks subjected to noise are broadly used to model physical and technological systems. Due to their nonlinear coupling, such networks typically have multiple stable and unstable states that a network might visit due to noise. In this article, we focus on the assessment of fluctuations resulting from heterogeneous and spatially correlated noise inputs on Kuramoto model networks. We evaluate the typical, small fluctuations near synchronized states and connect the network variance to the overlap between stable modes of synchronization and the input noise covariance. Going beyond small to large fluctuations, we introduce the indicator mode approximation that projects the dynamics onto a single amplitude dimension. Such an approximation allows for estimating rates of fluctuations to saddle instabilities, resulting in phase slips between connected oscillators. Statistics for both regimes are quantified in terms of effective noise amplitudes that are compared and contrasted for several noise models. In conclusion, bridging the gap between small and large fluctuations, we show that a larger network variance does not necessarily lead to higher rates of large fluctuations.

42 ENGINEERING↗
DOE OSTI2025

On the motion of compact objects in relativistic viscous fluids

We present a world-line effective field theory of compact objects moving relativistically through a viscous fluid. The theory is valid when velocity gradients are small compared to the inverse size of the object. Working within the EFT eliminates the need to solve a boundary value problem by turning all interactions between the fluid and the object into a source term in the action. We use the EFT to derive the relativistic equations of motion for a compact object immersed in a viscous fluid in a curved background, when the relative velocity of the object and the fluid is small compared to the speed of light.

astrophysical black holes↗
DOE OSTI2023

Magnetohydrodynamic stability of magnetars in the ultrastrong field regime – II. The crust

ABSTRACT We study the stability of Hall magnetohydrodynamic with strong magnetic fields in which Landau quantization of electrons is important. We find that the strong-field Hall modes can be destabilized by the dependence of the differential magnetic susceptibility on magnetic field strength. This hydrodynamic instability, thermodynamic in origin and stabilized by magnetic domain formation, is studied using linear perturbation theory. It is found to have typical growth time of order ≲103 yr, with the growth time decreasing as a function of wavelength of the perturbation. The instability is self-limiting, turning off following a period of local field growth by a few per cent of the initial value. Finite temperature is also shown to limit the instability, with sufficiently high temperatures eliminating it altogether. Alfvén waves can show similar unstable behaviour on shorter time-scales. We find that Ohmic heating due to the large fields developed via the instability and magnetic domain formation is not large enough to account for observed magnetar surface temperatures. However, Ohmic heating is enhanced by the oscillatory differential magnetic susceptibility of Landau-quantized electrons, which could be important to magnetothermal simulations of neutron star crusts.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2022

First-principles prediction of the Landau parameter for Fermi liquids near the unitarity limit

This paper explores the behavior of systems of cold fermions as they approach unitary above the critical temperature. Symmetry arguments indicate that at unitarity the Fermi-liquid picture breaks down. As we move away from unitarity, by decreasing the scattering length, the dilaton, the Goldstone boson resulting from the spontaneous breaking of Schrodinger symmetry by the Fermi sea, becomes gapped. At energies below this gap, the interaction between quasiparticles will be dominated by dilaton exchange. Here, the dilaton mass can, in turn, be related via anomaly matching to the scattering length and contact parameter within the confines of a systematic expansion.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2020

Virtual Hawking Radiation

We consider the effects of off-shell Hawking radiation on scattering processes involving black holes coupled to quantum fields. The focus here is to the case of gravitational scattering of a scalar field mediated by the exchange of virtual Hawking gravitons from a four-dimensional Schwarzschild black hole. Our result is obtained in the context of a worldline effective field theory for the black hole, and is valid in the semi-classical limit where the Schwarzschild radius rs is larger than the Planck length 1/m Pl . In addition, we assume that four-momentum exchange q is smaller than r s –1 and that the incoming particle has energy larger then the black hole's Hawking temperature. The inelastic cross section we obtain is a new, leading order quantum gravity effect, arising at the same order in q 2 /$m$ $^{2}_{Pl}$ as the well understood one-loop graviton vacuum polarization corrections to gravitational scattering between massive particles.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Effective Field Theory for Extreme Mass Ratio Binaries

We derive an effective field theory describing a pair of gravitationally interacting point particles in an expansion in their mass ratio, also known as the self-force (SF) expansion. The 0SF dynamics are trivially obtained to all orders in Newton’s constant by the geodesic motion of the light body in a Schwarzschild background encoding the gravitational field of the heavy body. The corrections at 1SF and higher are generated by perturbations about this configuration—that is, the geodesic deviation of the light body and the fluctuation graviton—but crucially supplemented by an operator describing the recoil of the heavy body as it interacts with the smaller companion. Using this formalism we compute new results at third post-Minkowskian order for the conservative dynamics of a system of gravitationally interacting massive particles coupled to a set of additional scalar and vector fields.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2021

The Algae Foundation® and Algae Technology Educational Consortium

Abstract The Algae Foundation established in February 2013 has developed a diverse portfolio of algal‐based education and workforce development programs covering education levels from kindergarten through college, aquaculture extension, and free online courses. The Algae Foundation created the Algae Technology Educational Consortium (ATEC) with five major foci including community college certificate program in algae cultivation; community college curriculum adopted for algal biotechnology degree programs; Algal Massive Open Online Courses (Algal MOOCs); Algae Academy, a kindergarten to 12th grade STEM curriculum initiative; and aquaculture extension education through the Algae Cultivation Extension Short courses (ACES). The results include the education and training of over 102,000 students, aquaculturists, entrepreneurs, and bioeconomy‐based professionals aged 8–75 years in all 50 U.S. states and 66 countries. ATEC has completed agreements with 21 community colleges and universities located in Arizona, California, Connecticut, Hawaii, Louisiana, Maine, New Mexico, North Carolina, Oregon, Texas, and Washington. The first ATEC‐sponsored certificate degree program graduation was in May 2018. The Algae MOOC #1 has had over 15,752 students enrolled. ATEC initiated the Algae Academy in spring 2016 in Carlsbad, CA, and expanded to serving over 34,000 students in 46 states during the academic year 2019–2020. ACES has enrolled over 1,550 students from 66 countries.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

Engineered Methylobacterium extorquens grows well on methoxylated aromatics due to its formaldehyde metabolism and stress response

ABSTRACT Lignin is a vast yet underutilized source of renewable energy. The microbial valorization of lignin is challenging due to the toxicity of its degradation intermediates, particularly formaldehyde. In this study, we engineeredMethylobacterium extorquensPA1 to metabolize lignin-derived methoxylated aromatics, vanillate (VA) and protocatechuate (PCA), by introducing thevanandpcagene clusters. Compared toPseudomonas putida,M. extorquensPA1 exhibited better formaldehyde detoxification, enabling robust growth on VA without accumulation of formaldehyde. Genetic analyses confirmed that formaldehyde oxidation and stress response systems, rather than C 1 assimilation, were important for VA metabolism. Additionally, VA and PCA were found to disrupt membrane potential, contributing to their inherent toxicity. Our findings establishM. extorquensPA1 as a promising chassis for lignin valorization and provide a framework for engineering formaldehyde-resistant microbial platforms. IMPORTANCE In developing biotechnological solutions for a circular economy, it is critical to valorize all parts of renewable resources, such as lignocellulose from vegetative components of agricultural crops and from bioenergy feedstocks. After chemical breakdown, the aromatics arising from lignin present significant challenges for use due to their toxicity. Here, we address one component of this challenge—the methoxy groups that get released as formaldehyde—and show that existing biotechnological platform organisms with strong formaldehyde metabolism, such asMethylobacterium extorquens, can be transformed into highly capable utilizers of methoxylated aromatics.

Microbiology↗
DOE OSTI2020

Fast Charge-Driven Li Plating on Anode and Structural Degradation of Cathode

Enabling fast charging in lithium ion batteries (LIBs) is a key factor to make electric vehicles drive just like gasoline-powered vehicles when the time comes to refuel. However, fast charging to current LIBs (LiNi x Mn y Co 1–z O 2 /graphite) is limited by lithium plating, which is barely reversible and causes LIBs to lose capacity over time. Thus, research to quantify the lithium plating in LIB cells is extremely important in improving our fundamental understanding of lithium plating behavior and enabling fast charging for LIBs. Here, we precisely quantified the amount of fast-charge-driven lithium plating in a coin-cell composed of LiNi 0.5 Mn 0.3 Co 0.2 O 2 (NMC532)/graphite. We found that the amount of lithium plating gradually increases with the cycle count and reaches 25.59 μmole (26.80 mAh g –1 cathode ) by the 100th cycle. The study also reveals that the NMC532 has lost 19% of its original lithium content after 100 fast-charging cycles; this, correspondingly, causes a lattice volumetric strain of 0.59%.

25 ENERGY STORAGE↗
DOE OSTI2020

Systematic Study of the Cathode Compositional Dependency of Cross-Talk Behavior in Li-Ion Battery

While LiNi x Mn y Co 1-x-y O 2 (NMC) is one of the most widely used cathode materials for lithium-ion batteries (LIBs), the composition of NMC is evolving to Ni-rich NMC to achieve higher lithium capacity that fulfills the constant demand for LIBs with ever-higher energy densities. The change in the composition of NMC affects electrochemical features and electrode cross-talk, which explains the performance change during cycling. Here in this study, we introduce various NMC materials (LiNi 0.5 Mn 0.3 Co 0.2 O 2 , LiNi 0.6 Mn 0.2 Co 0.2 O 2 and LiNi 0.8 Mn 0.1 Co 0.1 O 2 ) to reveal how the NMC composition affects electrode cross-talk. The study reveals that NMC composition strongly affects transition metal dissolution; dissolution of manganese linearly decreases as its stoichiometric ratio in NMC decreases, while dissolution of nickel is only prominent in LiNi 0.8 Mn 0.1 Co 0.1 O 2 . Aged electrolyte samples are characterized with high-performance liquid chromatography, and two electrolyte decomposition species, C 8 H 16 O 5 and C 9 H 18 O 5 , are identified across all samples.

25 ENERGY STORAGE↗