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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Collaborative R&D with First Solar on Understanding Performance Limitations in CdTe (Project 1 "CdTe" - Mods 0-10, 13, 14-A1, 17)

This CRADA involves analyses on a variety of CdTe and CdTe-PV related materials, test structures, and solar cells produced at FSLR or NREL. Single-crystal (sx) material will be primarily MBE grown and provided by FSLR. Joint activities are focused on establishing the appropriate quality metrics as a basis for high performing sx devices and to study the dopability of the material. Polycrystalline (px) materials will be provided by NREL, FSLR, or fabricated jointly. Px activities are focused on the characterization of performance limiting mechanisms including bulk defects, grain boundaries, and the hetero-interface. A combination of growth, characterization, and theory will be applied. Analysis will include techniques that are well established in CdTe research at NREL (e.g., LIV/DIV/CV, AS/DLTS, LTPL, TRPL) as well as techniques that have not been widely applied to the PV part of CdTe technology (e.g., PCD, CL, uPL, SE).

14 SOLAR ENERGY↗
DOE OSTI2021

Liner implosion experiments driven by a dynamic screw pinch

This paper expands upon recent experimental results [Campbell et al., Phys. Rev. Lett. 125, 035001 (2020)], where thin-foil liner implosions were driven by a dynamic screw pinch (DSP) and found to have magneto-Rayleigh–Taylor instability (MRTI) amplitudes up to three times smaller than in implosions driven by a standard z-pinch (SZP). Here, the expanded discussion presented herein includes: (1) a detailed comparison of the MRTI growth measured in the experiment with that calculated from theory; (2) measurements of axial magnetic field injection into the liner interior prior to the implosion, as well as the subsequent compression of this field during the implosion; (3) an in-depth description of how the helical geometry of the DSP can result in earlier implosion and stagnation times relative to the SZP; and (4) particle-in-cell simulations showing different electron drift behavior in the anode–cathode gap of the DSP relative to the SZP, and how this difference may be related to the different current waveforms recorded during the experiments.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1997

A novel culture morphology resulting from applied mechanical strain

To demonstrate that cells both perceive and respond to external force, a strain/relaxation regimen was applied to normal human fetal and aged dermal fibroblasts cultured as monolayers on flexible membranes. The precisely controlled protocol of stretch (20% elongation of the culture membrane) at 6.67 cycles/min caused a progressive change in the monolayers, such that the original randomly distributed pattern of cells became a symmetric, radial distribution as the cell bodies aligned parallel to the applied force. High cell density interfered with the success of re-alignment in the fetal cell cultures observed, which may reflect a preference in this cell strain for cell-cell over cell-matrix contacts. The chronologically aged cells observed did not demonstrate this feature, aligning efficiently at all seeding densities examined. The role of microfilaments in force perception and transmission was investigated through the addition of cytochalasin D in graded doses. Both intercellular interactions and cytoskeletal integrity mediate the morphological response to mechanical strain.

NASA Discipline Cell Biology↗
DOE OSTI2022

Heinz-resistant tomato cultivars exhibit a lignin-based resistance to field dodder ( Cuscuta campestris ) parasitism

Cuscuta species (dodders) are agriculturally destructive, parasitic angiosperms. These parasitic plants use haustoria as physiological bridges to extract nutrients and water from hosts. Cuscuta campestris has a broad host range and wide geographical distribution. While some wild tomato relatives are resistant, cultivated tomatoes are generally susceptible to C. campestris infestations. However, some specific Heinz tomato (Solanum lycopersicum) hybrid cultivars exhibit resistance to dodders in the field, but their defense mechanism was previously unknown. Here, we discovered that the stem cortex in these resistant lines responds with local lignification upon C. campestris attachment, preventing parasite entry into the host. Lignin Induction Factor 1 (LIF1, an AP2-like transcription factor), SlMYB55, and Cuscuta R-gene for Lignin-based Resistance 1, a CC-NBS-LRR (CuRLR1) are identified as factors that confer host resistance by regulating lignification. SlWRKY16 is upregulated upon C. campestris infestation and potentially negatively regulates LIF1 function. Intriguingly, CuRLR1 may play a role in signaling or function as an intracellular receptor for receiving Cuscuta signals or effectors, thereby regulating lignification-based resistance. In summary, these four regulators control the lignin-based resistance response in specific Heinz tomato cultivars, preventing C. campestris from parasitizing resistant tomatoes. This discovery provides a foundation for investigating multilayer resistance against Cuscuta species and has potential for application in other essential crops attacked by parasitic plants.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Broadening of the Divertor Heat Flux Profile in High Confinement Tokamak Fusion Plasmas with Edge Pedestals Limited by Turbulence in DIII-D

Multimachine empirical scaling predicts an extremely narrow heat exhaust layer in future high magnetic field tokamaks, producing high power densities that require mitigation. Here, in the experiments presented, the width of this exhaust layer is nearly doubled using actuators to increase turbulent transport in the plasma edge. This is achieved in low collisionality, high confinement edge pedestals with their gradients limited by turbulent transport instead of large-scale, coherent instabilities. The exhaust heat flux profile width and divertor leg diffusive spreading both double as a high frequency band of turbulent fluctuations propagating in the electron diamagnetic direction doubles in amplitude. The results are quantitatively reproduced in electromagnetic XGC particle-in-cell simulations which show the heat flux carried by electrons emerges to broaden the heat flux profile, directly supported by Langmuir probe measurements.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

ARIES/Flatirons Facility - Hydrogen System Capability Buildout

Under the "Advanced Research on Integrated Energy Systems" (ARIES) initiative, hydrogen system capabilities including a MW-scale electrolyzer, storage system, and MW-scale fuel cell generator will be designed and commissioned at NREL's Flatirons Campus. This hydrogen infrastructure will support H2@Scale goals by enabling integrated systems R&D to study the science of scaling for hydrogen energy systems.The system is designed with flexibility to provide a testbed to demonstrate systems integration, grid services, energy storage, direct renewable hydrogen production, and innovative end use applications (e.g. HD transportation, natural gas blending, etc.).

Advanced Research on Integrated Energy Systems↗
NASA NTRS2001

NASA/American Cancer Society High-Resolution Flow Cytometry Project-I

BACKGROUND: The NASA/American Cancer Society (ACS) flow cytometer can simultaneously analyze the electronic nuclear volume (ENV) and DNA content of cells. This study describes the schematics, resolution, reproducibility, and sensitivity of biological standards analyzed on this unit. METHODS: Calibrated beads and biological standards (lymphocytes, trout erythrocytes [TRBC], calf thymocytes, and tumor cells) were analyzed for ENV versus DNA content. Parallel data (forward scatter versus DNA) from a conventional flow cytometer were obtained. RESULTS: ENV linearity studies yielded an R value of 0.999. TRBC had a coefficient of variation (CV) of 1.18 +/- 0.13. DNA indexes as low as 1.02 were detectable. DNA content of lymphocytes from 42 females was 1.9% greater than that for 60 males, with a noninstrumental variability in total DNA content of 0.5%. The ENV/DNA ratio was constant in 15 normal human tissue samples, but differed in the four animal species tested. The ENV/DNA ratio for a hypodiploid breast carcinoma was 2.3 times greater than that for normal breast tissue. CONCLUSIONS: The high-resolution ENV versus DNA analyses are highly reliable, sensitive, and can be used for the detection of near-diploid tumor cells that are difficult to identify with conventional cytometers. ENV/DNA ratio may be a useful parameter for detection of aneuploid populations.

NASA Center JSC↗
NASA NTRS1997

Calbindin and parvalbumin are early markers of non-mitotically regenerating hair cells in the bullfrog vestibular otolith organs

Earlier studies have demonstrated hair cell regeneration in the absence of cell proliferation, and suggested that supporting cells could phenotypically convert into hair cells following hair cell loss. Because calcium-binding proteins are involved in gene up-regulation, cell growth, and cell differentiation, we wished to determine if these proteins were up-regulated in scar formations and regenerating hair cells following gentamicin treatment. Calbindin and parvalbumin immunolabeling was examined in control or gentamicin-treated (GT) bullfrog saccular and utricular explants cultured for 3 days in amphibian culture medium or amphibian culture medium supplemented with aphidicolin, a blocker of nuclear DNA replication in eukaryotic cells. In control cultures, calbindin and parvalbumin immunolabeled the hair bundles and, less intensely, the cell bodies of mature hair cells. In GT or mitotically-blocked GT (MBGT) cultures, calbindin and parvalbumin immunolabeling was also seen in the hair bundles, cuticular plates, and cell bodies of hair cells with immature hair bundles. Thus, these antigens were useful markers for both normal and regenerating hair cells. Supporting cell immunolabeling was not seen in control cultures nor in the majority of supporting cells in GT cultures. In MBGT cultures, calbindin and parvalbumin immunolabeling was up-regulated in the cytosol of single supporting cells participating in scar formations and in supporting cells with hair cell-like characteristics. These data provide further evidence that non-mitotic hair cell regeneration in cultures can be accomplished by the conversion of supporting cells into hair cells.

Non-NASA Center↗
NASA NTRS2000

Ca(2+) regulates fluid shear-induced cytoskeletal reorganization and gene expression in osteoblasts

Osteoblasts subjected to fluid shear increase the expression of the early response gene, c-fos, and the inducible isoform of cyclooxygenase, COX-2, two proteins linked to the anabolic response of bone to mechanical stimulation, in vivo. These increases in gene expression are dependent on shear-induced actin stress fiber formation. Here, we demonstrate that MC3T3-E1 osteoblast-like cells respond to shear with a rapid increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) that we postulate is important to subsequent cellular responses to shear. To test this hypothesis, MC3T3-E1 cells were grown on glass slides coated with fibronectin and subjected to laminar fluid flow (12 dyn/cm(2)). Before application of shear, cells were treated with two Ca(2+) channel inhibitors or various blockers of intracellular Ca(2+) release for 0. 5-1 h. Although gadolinium, a mechanosensitive channel blocker, significantly reduced the [Ca(2+)](i) response, neither gadolinium nor nifedipine, an L-type channel Ca(2+) channel blocker, were able to block shear-induced stress fiber formation and increase in c-fos and COX-2 in MC3T3-E1 cells. However, 1, 2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid-AM, an intracellular Ca(2+) chelator, or thapsigargin, which empties intracellular Ca(2+) stores, completely inhibited stress fiber formation and c-fos/COX-2 production in sheared osteoblasts. Neomycin or U-73122 inhibition of phospholipase C, which mediates D-myo-inositol 1,4,5-trisphosphate (IP(3))-induced intracellular Ca(2+) release, also completely suppressed actin reorganization and c-fos/COX-2 production. Pretreatment of MC3T3-E1 cells with U-73343, the inactive isoform of U-73122, did not inhibit these shear-induced responses. These results suggest that IP(3)-mediated intracellular Ca(2+) release is required for modulating flow-induced responses in MC3T3-E1 cells.

Non-NASA Center↗
NASA NTRS2013

Method for Enhancing a Three Dimensional Image from a Plurality of Frames of Flash LIDAR Data

A method for enhancing a three dimensional image from frames of flash LIDAR data includes generating a first distance R(sub i) from a first detector i to a first point on a surface S(sub i). After defining a map with a mesh theta having cells k, a first array S(k), a second array M(k), and a third array D(k) are initialized. The first array corresponds to the surface, the second array corresponds to the elevation map, and the third array D(k) receives an output for the DEM. The surface is projected onto the mesh theta, so that a second distance R(sub k) from a second point on the mesh theta to the detector can be found. From this, a height may be calculated, which permits the generation of a digital elevation map. Also, using sequential frames of flash LIDAR data, vehicle control is possible using an offset between successive frames.

Vanek, Michael D.↗
NASA NTRS2014

Methods of Real Time Image Enhancement of Flash LIDAR Data and Navigating a Vehicle Using Flash LIDAR Data

A method for creating a digital elevation map ("DEM") from frames of flash LIDAR data includes generating a first distance R(sub i) from a first detector i to a first point on a surface S(sub i). After defining a map with a mesh THETA having cells k, a first array S(k), a second array M(k), and a third array D(k) are initialized. The first array corresponds to the surface, the second array corresponds to the elevation map, and the third array D(k) receives an output for the DEM. The surface is projected onto the mesh THETA, so that a second distance R(sub k) from a second point on the mesh THETA to the detector can be found. From this, a height may be calculated, which permits the generation of a digital elevation map. Also, using sequential frames of flash LIDAR data, vehicle control is possible using an offset between successive frames.

Vanek, Michael D.↗
NASA NTRS1980

Impurities in silicon solar cells

The paper investigates the effects of metallic impurities on the performance of silicon solar cells. Czochralski and polycrystalline ingots were employed with boron and phosphorus as primary dopants and with controlled additions of secondary impurities. The data obtained from over 200 crystals indicate that impurity-induced performance loss is primarily due to a reduction of the base diffusion length. Based on this observation, a model is developed which predicts cell performance as a function of secondary impurity concentrations. The model calculations are in good agreement with experimental values except for Cu, Ni, Fe, and to a lesser degree, carbon, which at higher concentrations degrade the cell by junction defect mechanisms.

Davis, J. R., Jr.↗
NASA NTRS2001

Three-dimensional tissue assemblies: novel models for the study of Salmonella enterica serovar Typhimurium pathogenesis

The lack of readily available experimental systems has limited knowledge pertaining to the development of Salmonella-induced gastroenteritis and diarrheal disease in humans. We used a novel low-shear stress cell culture system developed at the National Aeronautics and Space Administration in conjunction with cultivation of three-dimensional (3-D) aggregates of human intestinal tissue to study the infectivity of Salmonella enterica serovar Typhimurium for human intestinal epithelium. Immunohistochemical characterization and microscopic analysis of 3-D aggregates of the human intestinal epithelial cell line Int-407 revealed that the 3-D cells more accurately modeled human in vivo differentiated tissues than did conventional monolayer cultures of the same cells. Results from infectivity studies showed that Salmonella established infection of the 3-D cells in a much different manner than that observed for monolayers. Following the same time course of infection with Salmonella, 3-D Int-407 cells displayed minimal loss of structural integrity compared to that of Int-407 monolayers. Furthermore, Salmonella exhibited significantly lower abilities to adhere to, invade, and induce apoptosis of 3-D Int-407 cells than it did for infected Int-407 monolayers. Analysis of cytokine expression profiles of 3-D Int-407 cells and monolayers following infection with Salmonella revealed significant differences in expression of interleukin 1alpha (IL-1alpha), IL-1beta, IL-6, IL-1Ra, and tumor necrosis factor alpha mRNAs between the two cultures. In addition, uninfected 3-D Int-407 cells constitutively expressed higher levels of transforming growth factor beta1 mRNA and prostaglandin E2 than did uninfected Int-407 monolayers. By more accurately modeling many aspects of human in vivo tissues, the 3-D intestinal cell model generated in this study offers a novel approach for studying microbial infectivity from the perspective of the host-pathogen interaction.

NASA Discipline Environmental Health↗
NASA NTRS1974

The development of a non-cryogenic nitrogen/oxygen supply system

A hydrazine/water electrolysis process system module design was fabricated and tested to demonstrate component and module performance. This module is capable of providing both the metabolic oxygen for crew needs and the oxygen and nitrogen for spacecraft leak makeup. The component designs evolved through previous R and D efforts, and were fabricated and tested individually and then were assembled into a complete module which was successfully tested for 1000 hours to demonstrate integration of the individual components. A survey was made of hydrazine sensor technology and a cell math model was derived.

Greenough, B. M.↗