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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 721 records · Page 40

All sources NASA NTRS DOE OSTI

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↗

DOE OSTI2023

Large-scale physically accurate modelling of real proton exchange membrane fuel cell with deep learning

Proton exchange membrane fuel cells, consuming hydrogen and oxygen to generate clean electricity and water, suffer acute liquid water challenges. Accurate liquid water modelling is inherently challenging due to the multi-phase, multi-component, reactive dynamics within multi-scale, multi-layered porous media. In addition, currently inadequate imaging and modelling capabilities are limiting simulations to small areas (<1 mm 2 ) or simplified architectures. Herein, an advancement in water modelling is achieved using X-ray micro-computed tomography, deep learned super-resolution, multi-label segmentation, and direct multi-phase simulation. The resulting image is the most resolved domain (16 mm 2 with 700 nm voxel resolution) and the largest direct multi-phase flow simulation of a fuel cell. This generalisable approach unveils multi-scale water clustering and transport mechanisms over large dry and flooded areas in the gas diffusion layer and flow fields, paving the way for next generation proton exchange membrane fuel cells with optimised structures and wettabilities.

25 ENERGY STORAGE↗

NASA NTRS1977

Regenerable device for scrubbing breathable air of CO2 and moisture without special heat exchanger equipment

The device concerns the circulation of cabin air through canisters which absorb and adsorb carbon dioxide, together with excess moisture, and return the scrubbed air to the cabin for recirculation. A coating on an inert substrate in granular form absorbs and adsorbs the impurities at standard temperatures and pressures, but desorbs such impurities at low pressures (vacuum) and standard temperatures. This fact is exploited by making the device in a stack of cells consisting of layers or cells which are isolated from one another flow-wise and are connected to separate manifolds and valving systems into two separate subsets. A first subset may be connected for the flow breathable air therethrough until the polyethyleneimine of its cells is saturated with CO2 and H2O. During the same period the second subset of cells is manifolded to a vacuum source.

Tepper, E. H.↗

NASA NTRS1983

Striped Electrodes for Solid-Electrolyte Cells

Striped thick-film platinum electrodes help insure lower overall cell resistance by permitting free flow of gases in gaps between stripes. Thickfilm stripes are also easier to fabricate than porous thin-film electrodes that cover entire surface. Possible applications for improved cells include oxygen production from carbon dioxide, extraction of oxygen from air, small fluidic pumping, sewage treatment, and fuel cells.

Richter, R.↗

NASA NTRS1993

Ceramic distribution members for solid state electrolyte cells and method of producing

A solid state electrolyte cells apparatus and method of producing is disclosed. The apparatus can be used for separating oxygen from an oxygen-containing feedstock or as a fuel cell for reacting fluids. Cells can be stacked so that fluids can be introduced and removed from the apparatus through ceramic distribution members having ports designed for distributing the fluids in parallel flow to and from each cell. The distribution members can also serve as electrodes to membranes or as membrane members between electrodes. The distribution member design does not contain any horizontal internal ports which allows the member to be thin. A method of tape casting in combination with an embossing method allows intricate radial ribs and bosses to be formed on each distribution member. The bosses serve as seals for the ports and allow the distribution members to be made without any horizontal internal ports.

Clark, Douglas J.↗

NASA NTRS1995

Method of producing ceramic distribution members for solid state electrolyte cells

A solid state electrolyte cells apparatus and method of producing is disclosed. The apparatus can be used for separating oxygen from an oxygen-containing feedstock or as a fuel cell for reacting fluids. Cells can be stacked so that fluids can be introduced and removed from the apparatus through ceramic distribution members having ports designed for distributing the fluids in parallel flow to and from each cell. The distribution members can also serve as electrodes to membranes or as membrane members between electrodes, The distribution member design does not contain any horizontal internal ports which allows the member to be thin. A method of tape casting in combination with an embossing method allows intricate radial ribs and bosses to be formed on each distribution member. The bosses serve as seals for the ports and allow the distribution members to be made without any horizontal internal ports.

Clark, Douglas J.↗

NASA NTRS2001

Optimized suspension culture: the rotating-wall vessel

Suspension culture remains a popular modality, which manipulates mechanical culture conditions to maintain the specialized features of cultured cells. The rotating-wall vessel is a suspension culture vessel optimized to produce laminar flow and minimize the mechanical stresses on cell aggregates in culture. This review summarizes the engineering principles, which allow optimal suspension culture conditions to be established, and the boundary conditions, which limit this process. We suggest that to minimize mechanical damage and optimize differentiation of cultured cells, suspension culture should be performed in a solid-body rotation Couette-flow, zero-headspace culture vessel such as the rotating-wall vessel. This provides fluid dynamic operating principles characterized by 1) solid body rotation about a horizontal axis, characterized by colocalization of cells and aggregates of different sedimentation rates, optimally reduced fluid shear and turbulence, and three-dimensional spatial freedom; and 2) oxygenation by diffusion. Optimization of suspension culture is achieved by applying three tradeoffs. First, terminal velocity should be minimized by choosing microcarrier beads and culture media as close in density as possible. Next, rotation in the rotating-wall vessel induces both Coriolis and centrifugal forces, directly dependent on terminal velocity and minimized as terminal velocity is minimized. Last, mass transport of nutrients to a cell in suspension culture depends on both terminal velocity and diffusion of nutrients. In the transduction of mechanical culture conditions into cellular effects, several lines of evidence support a role for multiple molecular mechanisms. These include effects of shear stress, changes in cell cycle and cell death pathways, and upstream regulation of secondary messengers such as protein kinase C. The discipline of suspension culture needs a systematic analysis of the relationship between mechanical culture conditions and biological effects, emphasizing cellular processes important for the industrial production of biological pharmaceuticals and devices.

Non-NASA Center↗

NASA NTRS1986

Heat dissipation of high rate Li-SOCl sub 2 primary cells

The heat dissipation problem occurring in the lithium thionyl chloride cells discharged at relatively high rates under normal discharge conditions is examined. Four heat flow paths were identified, and the thermal resistances of the relating cell components along each flow path were accordingly calculated. From the thermal resistance network analysis, it was demonstrated that about 90 percent of the total heat produced within the cell should be dissipated along the radial direction in a spirally wound cell. In addition, the threshold value of the heat generation rate at which cell internal temperature could be maintained below 100 C, was calculated from total thermal resistance and found to be 2.9 W. However, these calculations were made only at the cell components' level, and the transient nature of the heat accumulation and dissipation was not considered. A simple transient model based on the lumped-heat-capacity concept was developed to predict the time-dependent cell temperature at different discharge rates. The overall objective was to examine the influence of cell design variable from the heat removal point of view under normal discharge conditions and to make recommendations to build more efficient lithium cells.

Cho, Y. I.↗

NASA NTRS1983

Aerothermodynamic design considerations of an aerobraked spacecraft

The major aerothermodynamic design issues that influenced the VOIR (Venus Orbiting Image Radar) airbrake and mission design are discussed. In the discussion of aerobrake heating, it is pointed out that the heat transfer to the deployed aerobrake is a function of the flow regime encountered during the periapsis pass, the perapsis altitude, and the brake surface geometry. The discussion of spacecraft thermal protection encompasses separated flow heating, aerobrake backface radiation, total solar cell heating, and undeployed aerobrake effects. The aerobrake is designed to protect the spacecraft thermally by limiting the integrated entry heating to the critical solar cell arrays (located on three sides of the spacecraft) due to flow impingement heating, separated flow heating, and backface radiation heating. It is explained that these design considerations led to the selection of a flat-faced aerobrake design located on the front of the spacecraft to provide maximum spacecraft thermal protection. The 8.4-m equivalent diameter aerobrake eliminates direct flow impingement heating and lowers separated flow heating on the spacecraft.

Florence, D.↗

NASA NTRS1994

Effects of hypergravity on immunologic function

The purpose of this study was to compare the effects of hypergravity exposure (2g) with those of exposure to space flight in the Cosmos 2044 flight. To do so, rats were centrifuged continuously for 14 days. Two different experiments were carried out on tissue obtained from the centrifuged rats. In the first experiment, rat bone marrow cells were examined for their response to recombinant murine colony stimulating factor-granulocyte/monocyte (GM-CSF). In the second experiment, rate spleen and bone marrow cells were stained in with a variety of antibodies directed against cell surface antigenic markers. These cells were preserved and analyzed on a flow cytometer. The results of the studies indicated that bone marrow cells from centrifuged rats showed no significant change in response to GM-CSF as compared to bone marrow cells from control rats. Spleen cells from flown rats showed some statistically significant changes in leukocytes subset distribution, but no differences that appeared to be of biological significance. These results indicate that hypergravity did not greatly affect the same immunological parameters affected by space flight in the Cosmos 2044 mission.

Sonnenfeld, G.↗

NASA NTRS1995

Effects of hypergravity on immunologic function

The purpose of this study was to compare the effects of hypergravity exposure (2g) with those of exposure to space flight in the Cosmos 2044 flight. To do so, rats were centrifuged continuously for 14 days. Two different experiments were carried out on tissue obtained from the centrifuged rats. In the first experiment, rat bone marrow cells were examined for their response to recombinant murine colony stimulating factor-granulocyte/monocyte (GM-CSF). In the second experiment, rat spleen and bone marrow cells were stained in with a variety of antibodies directed against cell surface antigenic markers. These cells were preserved and analyzed on a flow cytometer. The results of the studies indicated that bone marrow cells from centrifuged rats showed no significant change in response to GM-CSF as compared to bone marrow cells from control rats. Spleen cells from flown rats showed some statistically significant changes in leukocytes subset distribution, but no differences that appeared to be of biological significance. These results indicate that hypergravity did not greatly affect the same immunological parameters affected by space flight in the Cosmos 2044 mission.

NASA Program Flight↗

NASA NTRS2014

Method for Making a Fuel Cell from a Solid Oxide Monolithic Framework

The invention is a novel solid oxide fuel cell (SOFC) stack comprising individual bi-electrode supported fuel cells in which a thin electrolyte is supported between electrodes of essentially equal thickness. Individual cell units are made from graded pore ceramic tape that has been created by the freeze cast method followed by freeze drying. Each piece of graded pore tape later becomes a graded pore electrode scaffold that subsequent to sintering, is made into either an anode or a cathode by means of appropriate solution and thermal treatment means. Each cell unit is assembled by depositing of a thin coating of ion conducting ceramic material upon the side of each of two pieces of tape surface having the smallest pore openings, and then mating the coated surfaces to create an unsintered electrode scaffold pair sandwiching an electrolyte layer. The opposing major outer exposed surfaces of each cell unit is given a thin coating of electrically conductive ceramic, and multiple cell units are stacked, or built up by stacking of individual cell layers, to create an unsintered fuel cell stack. Ceramic or glass edge seals are installed to create flow channels for fuel and air. The cell stack with edge sealants is then sintered into a ceramic monolithic framework. Said solution and thermal treatments means convert the electrode scaffolds into anodes and cathodes. The thin layers of electrically conductive ceramic become the interconnects in the assembled stack.

Cable, Thomas L.↗

DOE OSTI2021

Analytical modeling for redox flow battery design

Deeper market penetration of redox flow batteries requires optimization of the cell performance. Though important for optimization, detailed analytical solutions have not been developed for electrolyte flow, mass and charge transport, and reaction kinetics within redox flow batteries. To this end, here we present analytical solutions to active species concentration and over-potential based on advection-diffusion transport for ions and Bulter-Volmer model for interface reaction kinetics. The solutions were validated with results from a finite element model. These solutions were then applied to investigate the relationship between over-potential and state of charge, current density, reaction rate constant, flow velocity, diffusivity, total active species concentration, and electrode structure. Explicit formulas were identified for minimum activation over-potential and limiting current density as well as their dependence on electrolyte properties, operation conditions, and electrode structure. With our new mathematical formulas, this work provides a theoretical framework for flow battery design.

25 ENERGY STORAGE↗

DOE OSTI2021

Incomplete radiofrequency ablation induced chemoresistance by up-regulating heat shock protein 70 in hepatocellular carcinoma

Highlights: • iRFA treatment inhibited cisplatin-induced pyroptosis of HCC cells. • Heat shock protein 70 was involved in the suppression of NLRP3 activation. • iRFA treatment decreased the cisplatin sensitivity of HCC through regulating HSP70. Radiofrequency ablation (RFA) is a common minimally invasive treatment for hepatocellular carcinoma (HCC). Incomplete RFA (iRFA) due to the sub-lethal heat shock challenge of some cell populations leads to the generation of transformed survivor cells with enhanced chemoresistance. However, the underlying mechanism of iRFA on HCCs chemoresistance remains unknown. In the present study, we investigated the effect of iRFA on HCCs sensitivity to cisplatin. Cells treated with the sub-lethal heat shock challenge were used to mimic iRFA treatment in vitro. An orthotopic implantation HCC model was established and also performed iRFA treatment. Flow cytometry, transwell assay, and cell counting kit-8 assay were used to determine the effect of iRFA treatment on cisplatin-induced HCC cell apoptosis, invasion, and cell viability. ELISA and Western blot were used to detect the effect of iRFA treatment on cisplatin-induced HCC cell pyroptosis. We found that iRFA treatment increased the HCC cell proliferation and invasion ability, and inhibited cisplatin-induced pyroptosis. Further experiments showed that iRFA treatment induced upregulation of HSP70, which inhibited the cisplatin-induced NLRP3 inflammasome activation, leading to inhibition of pyroptosis. HSP70 knockdown or NLRP3 overexpression could reverse the effect of iRFA treatment in vitro. In vivo, HSP70 knockdown reversed the chemosensitivity of HCC to cisplatin, which was decreased by iRFA. In conclusion, we demonstrated that iRFA induced drug resistance by HSP70-mediated inhibition of cell pyroptosis in HCC.

60 APPLIED LIFE SCIENCES↗

NASA NTRS2011

NASA Engineering and Safety Center Technical Bulletin No. 11-01: Nickel-Hydrogen (NiH 2 ) Common Pressure Vessel (CPV) Cell Capacity Loss and Voltage Collapse

During an investigation of anomalous voltages during a NASA scientific mission, a NASA Engineering and Safety Center (NESC) team discovered that the design of NiH 2 CPV batteries may be susceptible to a unique electrolyte bridging between the two internal cells resulting in undesired ionic current flow. This condition can lead to depletion of the capacity within one of the two cells.

Nickel-Hydrogen↗

NASA NTRS2003

Measurements of cell-generated deformations on flexible substrata using correlation-based optical flow

The optical flow algorithm presented here is a robust method that rapidly yields a high-density field of substrate displacement vectors based on two optical images. We found that one of the limiting factors, at least for inexperienced experimentalists, is the consistency of focusing or the drift in microscope focus. However, with properly collected images the standard error of the measurement was estimated to be on the order of +/- 0.10 pixels. Finally, although the discussion has been focused on the displacement of flexible substrata, a similar method should be applicable for detecting movements on other types of images, as long as the movement involves a certain degree of local coordination.

Non-NASA Center↗

NASA NTRS1989

Three-dimensional calculations for underexpanded and overexpanded supersonic jet flows

A three-dimensional code is developed to simulate the characteristics of the jet exhaust plume issuing from nonaxisymmetric nozzles at different flight conditions. In the present paper, the time-iterative Space Marching Scheme (SMS) is used to simulate the shock-cell structure of underexpanded supersonic jet issued from round and square nozzles. Also, the computational results are compared with the experimental data from underexpanded and overexpanded supersonic round jets. The agreement with the experimental data validates the applicability of the new technique for predicting the shock-cell structure of supersonic jet flows. The computational results reveals that the azimuthal structure of the supersonic square jet changed as the jet progressed downstream of the exit nozzle.

Abdol-Hamid, Khaled S.↗

DOE OSTI2021

3D Printed Nickel–Molybdenum-Based Electrocatalysts for Hydrogen Evolution at Low Overpotentials in a Flow-Through Configuration

Three-dimensional (3D) printed, hierarchically porous nickel molybdenum (NiMo) electrocatalysts were synthesized and evaluated in a flow-through configuration for the hydrogen evolution reaction (HER) in 1.0 M KOH(aq) in a simple electrochemical H-cell. 3D NiMo electrodes possess hierarchically porous structures because of the resol-based aerogel precursor, which generates superporous carbon aerogel as a catalyst support. Relative to a traditional planar electrode configuration, the flow-through configuration allowed efficient removal of the hydrogen bubbles from the catalyst surface, especially at high operating current densities, and significantly decreased the overpotentials required for HER. An analytical model that accounted for the electrokinetics of HER as well as the mass transport with or without the flow-through configuration was developed to quantitatively evaluate voltage losses associated with kinetic overpotentials and ohmic resistance due to bubble formation in the porous electrodes. Furthermore, the chemical composition, electrochemical surface area (ECSA), and roughness factor (RF) were also systematically studied to assess the electrocatalytic performance of the 3D printed, hierarchically porous NiMo electrodes. An ECSA of 25163 cm2 was obtained with the highly porous structures, and an average overpotential of 45 mV at 10 mA cm–2 was achieved over 24 h by using the flow-through configuration. The flow-through configuration evaluated in the simple H-cell achieved high electrochemical accessible surface areas for electrochemical reactions and provided useful information for adaption of the porous electrodes in flow cells.

08 HYDROGEN↗