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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 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Regulation of the regulator of G protein signaling 2 expression and cellular localization by PKA and PKC pathways in mouse granulosa cells

G protein-coupled receptor (GPCR) activation-mediated PKA and PKC pathways have been recognized to be important in ovarian physiology. Expression of regulator of G-protein signaling 2 (RGS2) has been reported in ovarian granulosa cells. The detailed mechanisms in PKA- and PKC-regulated RGS2 expression and cellular translocation in granulosa cells remain mostly unclear. PKA activator 8-bromo-cAMP and PKC activator phorbol-12, 13-didecanoate appeared to rapidly elevate both protein and mRNA levels and promoter activation of RGS2 gene. Two consensus Sp1 elements within the shortest 78 bp fragment of RGS2 promoter sequence were essential for the full responsiveness to PKA and PKC. PKC activation appeared to increase the RGS2 translocation from nucleus to cytosol. PKA- and PKC-mediated RGS2 transcription in a Sp-1-dependent manner and a PKC-mediated RGS2 intracellular translocation were noted in granulosa cells.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Non-catalytic signaling by pseudokinase ILK for regulating cell adhesion

Dynamic communication between integrin-containing complexes (focal adhesions, FAs) and actin filaments is critical for regulating cell adhesion. Pseudokinase ILK plays a key role in this process but the underlying mechanism remains highly elusive. Here in this paper we show that by recruiting FA adaptors PINCH and Parvin into a heterotrimeric complex (IPP), ILK triggers F-actin filament bundling – a process known to generate force/mechanical signal to promote cytoskeleton reassembly and dynamic cell adhesion. Structural, biochemical, and functional analyses revealed that the F-actin bundling is orchestrated by two previously unrecognized WASP-Homology-2 actin binding motifs within IPP, one from PINCH and the other from Parvin. Strikingly, this process is also sensitized to Mg-ATP bound to the pseudoactive site of ILK and its dysregulation severely impairs stress fibers formation, cell spreading, and migration. These data identify a crucial mechanism for ILK, highlighting its uniqueness as a pseudokinase to transduce non-catalytic signal and regulate cell adhesion.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Efficient thermal management of Li-ion batteries with a passive interfacial thermal regulator based on a shape memory alloy [A passive interfacial thermal regulator based on shape memory alloy and its application to battery thermal management]

The poor performance of lithium-ion batteries in extreme temperatures is hindering their wider adoption in the energy sector. A fundamental challenge in battery thermal management systems (BTMSs) is that hot and cold environments pose opposite requirements: thermal transmission at high temperature for battery cooling, and thermal isolation at low temperature to retain the batteries’ internally generated heat, leading to an inevitable compromise of either hot or cold performances. Here, we demonstrate a thermal regulator that adjusts its thermal conductance as a function of the temperature, just as desired for the BTMS. Without any external logic control, this thermal regulator increases battery capacity by a factor of 3 at an ambient temperature (T ambient ) of -20 °C in comparison to a baseline BTMS that is always thermally conducting, while also limiting the battery temperature rise to 5 °C in a very hot environment (T ambient = 45 °C) to ensure safety. The result expands the usability of lithium-ion batteries in extreme environments and opens up new applications of thermally functional devices.

25 ENERGY STORAGE↗
DOE OSTI2015

Self-regulated growth of LaVO{sub 3} thin films by hybrid molecular beam epitaxy

LaVO{sub 3} thin films were grown on SrTiO{sub 3} (001) by hybrid molecular beam epitaxy. A volatile metalorganic precursor, vanadium oxytriisopropoxide (VTIP), and elemental La were co-supplied in the presence of a molecular oxygen flux. By keeping the La flux fixed and varying the VTIP flux, stoichiometric LaVO{sub 3} films were obtained for a range of cation flux ratios, indicating the presence of a self-regulated growth window. Films grown under stoichiometric conditions were found to have the largest lattice parameter, which decreased monotonically with increasing amounts of excess La or V. Energy dispersive X-ray spectroscopy and Rutherford backscattering measurements were carried out to confirm film compositions. Stoichiometric growth of complex vanadate thin films independent of cation flux ratios expands upon the previously reported self-regulated growth of perovskite titanates using hybrid molecular beam epitaxy, thus demonstrating the general applicability of this growth approach to other complex oxide materials, where a precise control over film stoichiometry is demanded by the application.

36 MATERIALS SCIENCE↗
DOE OSTI2011

Galaxy Formation with Self-Consistently Modeled Stars and Massive Black Holes. I: Feedback-Regulated Star Formation and Black Hole Growth

There is mounting evidence for the coevolution of galaxies and their embedded massive black holes (MBHs) in a hierarchical structure formation paradigm. To tackle the nonlinear processes of galaxy-MBH interaction, we describe a self-consistent numerical framework which incorporates both galaxies and MBHs. The high-resolution adaptive mesh refinement (AMR) code Enzo is modified to model the formation and feedback of molecular clouds at their characteristic scale of 15.2 pc and the accretion of gas onto an MBH. Two major channels of MBH feedback, radiative feedback (X-ray photons followed through full three-dimensional adaptive ray tracing) and mechanical feedback (bipolar jets resolved in high-resolution AMR), are employed. We investigate the coevolution of a 9.2 x 10{sup 11} M {circle_dot} galactic halo and its 10{sup 5} {circle_dot} M embedded MBH at redshift 3 in a cosmological CDM simulation. The MBH feedback heats the surrounding interstellar medium (ISM) up to 10{sup 6} K through photoionization and Compton heating and locally suppresses star formation in the galactic inner core. The feedback considerably changes the stellar distribution there. This new channel of feedback from a slowly growing MBH is particularly interesting because it is only locally dominant and does not require the heating of gas globally on the disk. The MBH also self-regulates its growth by keeping the surrounding ISM hot for an extended period of time.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2020

CamRegBase: a gene regulation database for the biofuel crop, Camelina sativa

Abstract Camelina is an annual oilseed plant from the Brassicaceae family that is gaining momentum as a biofuel winter cover crop. However, a significant limitation in further enhancing its utility as a producer of oils that can be used as biofuels, jet fuels or bio-based products is the absence of a repository for all the gene expression and regulatory information that is being rapidly generated by the community. Here, we provide CamRegBase (https://camregbase.org/) as a one-stop resource to access Camelina information on gene expression and co-expression, transcription factors, lipid associated genes and genome-wide orthologs in the close-relative reference plant Arabidopsis. We envision this as a resource of curated information for users, as well as a repository of new gene regulation information.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

Arabidopsis Forkhead-Associated Domain Protein 3 negatively regulates peroxisome division

Peroxisomes are ubiquitous and dynamic eukaryotic organelles capable of altering their abundance in response to environmental and developmental cues, yet the regulatory mechanism of plant peroxisome division/proliferation is unclear. To identify transcriptional regulators of the peroxisome division factor gene PEX 11b , we performed a nuclear pull-down experiment and identified Arabidopsis Forkhead-Associated Domain Protein 3 (FHA 3 ) as a novel protein that binds to the promoter of PEX 11b . Our data supported the conclusion that, in contrast to the previously identified HY5 HOMOLOG (HYH) protein that promotes the transcription of PEX 11b , FHA 3 is a negative regulator of PEX 11b expression and peroxisome division.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1979

Robustness properties of discrete time regulators, LOG regulators and hybrid systems

Robustness properites of sample-data LQ regulators are derived which show that these regulators have fundamentally inferior uncertainty tolerances when compared to their continuous-time counterparts. Results are also presented in stability theory, multivariable frequency domain analysis, LQG robustness, and mathematical representations of hybrid systems.

Stein, G.↗
NASA NTRS2000

Caveolin-1 regulates shear stress-dependent activation of extracellular signal-regulated kinase

Fluid shear stress activates a member of the mitogen-activated protein (MAP) kinase family, extracellular signal-regulated kinase (ERK), by mechanisms dependent on cholesterol in the plasma membrane in bovine aortic endothelial cells (BAEC). Caveolae are microdomains of the plasma membrane that are enriched with cholesterol, caveolin, and signaling molecules. We hypothesized that caveolin-1 regulates shear activation of ERK. Because caveolin-1 is not exposed to the outside, cells were minimally permeabilized by Triton X-100 (0.01%) to deliver a neutralizing, polyclonal caveolin-1 antibody (pCav-1) inside the cells. pCav-1 then bound to caveolin-1 and inhibited shear activation of ERK but not c-Jun NH(2)-terminal kinase. Epitope mapping studies showed that pCav-1 binds to caveolin-1 at two regions (residues 1-21 and 61-101). When the recombinant proteins containing the epitopes fused to glutathione-S-transferase (GST-Cav(1-21) or GST-Cav(61-101)) were preincubated with pCav-1, only GST-Cav(61-101) reversed the inhibitory effect of the antibody on shear activation of ERK. Other antibodies, including m2234, which binds to caveolin-1 residues 1-21, had no effect on shear activation of ERK. Caveolin-1 residues 61-101 contain the scaffolding and oligomerization domains, suggesting that binding of pCav-1 to these regions likely disrupts the clustering of caveolin-1 or its interaction with signaling molecules involved in the shear-sensitive ERK pathway. We suggest that caveolae-like domains play a critical role in the mechanosensing and/or mechanosignal transduction of the ERK pathway.

Non-NASA Center↗
DOE OSTI2011

The Min Oscillator Uses MinD-Dependent Conformational Changes in MinE to Spatially Regulate Cytokinesis.

In E. coli, MinD recruits MinE to the membrane, leading to a coupled oscillation required for spatial regulation of the cytokinetic Z ring. How these proteins interact, however, is not clear because the MinD-binding regions of MinE are sequestered within a six-stranded {beta} sheet and masked by N-terminal helices. minE mutations that restore interaction between some MinD and MinE mutants were isolated. These mutations alter the MinE structure leading to release of the MinD-binding regions and the N-terminal helices that bind the membrane. Crystallization of MinD-MinE complexes revealed a four-stranded {beta} sheet MinE dimer with the released {beta} strands (MinD-binding regions) converted to {alpha} helices bound to MinD dimers. These results identify the MinD-dependent conformational changes in MinE that convert it from a latent to an active form and lead to a model of how MinE persists at the MinD-membrane surface.

59 BASIC BIOLOGICAL SCIENCES↗