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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 523 records · Page 29
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Regulation of galactan synthase expression to modify galactan content in plants

The disclosure provides methods of engineering plants to modulate galactan content. Specifically, the disclosure provides methods for engineering a plant to increase the galactan content in a plant tissue by inducing expression of beta-1,4-galactan synthase (GALS), modulated by a heterologous promoter. Further disclosed are the methods of modulating expression level of GALS under the regulation of a transcription factor, as well as overexpression of UDP-galactose epimerse in the same plant tissue. Tissue specific promoters and transcription factors can be used in the methods are also provided.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2011

Analysis of the D+ --> K- pi+ e+ nu_e decay channel

Using 347.5 fb{sup -1} of data recorded by the BABAR detector at the PEP-II electron-positron collider, 244 x 10{sup 3} signal events for the D{sup +} {yields} K{sup -}{pi}{sup +}e{sup +}{nu}{sub e} decay channel are analyzed. This decay mode is dominated by the {bar K}*(892){sup 0} contribution. We determine the {bar K}*(892){sup 0} parameters: m{sub K*(892){sup 0}} = (895.4{+-}0.2{+-}0.2) MeV/c{sup 2}, {Lambda}{sub K*(892){sup 0}}{sup 0} = (46.5{+-}0.3{+-}0.2) MeV/c{sup 2} and the Blatt-Weisskopf parameter r{sub BW} = 2.1{+-}0.5{+-}0.5 (GeV/c){sup -1} where the first uncertainty comes from statistics and the second from systematic uncertainties. We also measure the parameters defining the corresponding hadronic form factors at q{sup 2} = 0 (r{sub V} = V(0)/A{sub 1}(0) = 1.463{+-}0.017{+-}0.031, r{sup 2} = A{sub 2}(0)/A{sub 1}(0) = 0.801{+-}0.020{+-}0.020) and the value of the axial-vector pole mass parameterizing the q{sup 2} variation of A{sub 1} and A{sub 2}: m{sub A} = (2.63{+-}0.10{+-}0.13) GeV/c{sup 2}. The S-wave fraction is equal to (5.79{+-}0.16{+-}0.15)%. Other signal components correspond to fractions below 1%. Using the D{sup +} {yields} K{sup -}{pi}{sup +}{pi}{sup +} channel as a normalization, we measure the D{sup +} semileptonic branching fraction: {Beta}(D{sup +} {yields} K{sup -}{pi}{sup +}e{sup +}{nu}{sub e}) = (4.00 {+-} 0.03 {+-} 0.04 {+-} 0.09) x 10{sup -2} where the third uncertainty comes from external inputs. We then obtain the value of the hadronic form factor A{sub 1} at q{sup 2} = 0: A{sub 1}(0) = 0.6200 {+-} 0.0056 {+-} 0.0065 {+-} 0.0071. Fixing the P-wave parameters we measure the phase of the S-wave for several values of the K{pi} mass. These results confirm those obtained with K{pi} production at small momentum transfer in fixed target experiments.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2013

Diffractive production of charm quark/antiquark pairs at RHIC and LHC

We have discussed single and central diffractive production of c(bar sign)c pairs in the Ingelman-Schlein model. In these calculations we have included diffractive parton distributions obtained by the H1 collaboration at HERA and absorption effects neglected in some early calculations in the literature. The absorption effects which are responsible for the naive Regge factorization breaking cause that the cross section for diffractive processes is much smaller than that for the fully inclusive case, but could be measured at RHIC and LHC by imposing special condition on rapidity gaps. We discuss also different approaches to diffractive production of heavy quark/antiquark [1, 2, 3]. The particular mechanism is similar to the diffractive dissociation of virtual photons into quarks, which drives diffractive deep inelastic production of charm in the low-mass diffraction, or large {beta}-region.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Homeobox A7 stimulates breast cancer cell proliferation by up-regulating estrogen receptor-alpha

Highlights: •HOXA7 regulates MCF7 cell proliferation. •HOXA7 up-regulates ERα expression. •HOXA7 mediates estrogen-induced MCF7 cell proliferation. -- Abstract: Breast cancer is the most common hormone-dependent malignancy in women. Homeobox (HOX) transcription factors regulate many cellular functions, including cell migration, proliferation and differentiation. The aberrant expression of HOX genes has been reported to be associated with human reproductive cancers. Estradiol (E2) and its nuclear receptors, estrogen receptor (ER)-alpha and ER-beta, are known to play critical roles in the regulation of breast cancer cell growth. However, an understanding of the potential relationship between HOXA7 and ER in breast cancer cells is limited. In this study, our results demonstrate that knockdown of HOXA7 in MCF7 cells significantly decreased cell proliferation and ERα expression. In addition, HOXA7 knockdown attenuated E2-induced cell proliferation as well as progesterone receptor (PR) expression. The stimulatory effects of E2 on cell proliferation and PR expression were abolished by co-treatment with ICI 182780, a selective ERα antagonist. In contrast, overexpression of HOXA7 significantly stimulated cell proliferation and ERα expression. Moreover, E2-induced cell proliferation, as well as PR expression, was enhanced by the overexpression of HOXA7. Neither knockdown nor overexpression of HOXA7 affected the ER-beta levels. Our results demonstrate a novel mechanistic role for HOXA7 in modulating breast cancer cell proliferation via regulation of ERα expression. This finding contributes to our understanding of the role HOXA7 plays in regulating the proliferation of ER-positive cancer cells.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

A structural model of anti-anti-[sigma] inhibition by a two-component receiver domain: the PhyR stress response regulator

PhyR is a hybrid stress regulator conserved in {alpha}-proteobacteria that contains an N-terminal {sigma}-like (SL) domain and a C-terminal receiver domain. Phosphorylation of the receiver domain is known to promote binding of the SL domain to an anti-{sigma} factor. PhyR thus functions as an anti-anti-{sigma} factor in its phosphorylated state. We present genetic evidence that Caulobacter crescentus PhyR is a phosphorylation-dependent stress regulator that functions in the same pathway as {sigma}{sup T} and its anti-{sigma} factor, NepR. Additionally, we report the X-ray crystal structure of PhyR at 1.25 {angstrom} resolution, which provides insight into the mechanism of anti-anti-{sigma} regulation. Direct intramolecular contact between the PhyR receiver and SL domains spans regions {sigma}{sub 2} and {sigma}{sub 4}, likely serving to stabilize the SL domain in a closed conformation. The molecular surface of the receiver domain contacting the SL domain is the structural equivalent of {alpha}4-{beta}5-{alpha}5, which is known to undergo dynamic conformational change upon phosphorylation in a diverse range of receiver proteins. We propose a structural model of PhyR regulation in which receiver phosphorylation destabilizes the intramolecular interaction between SL and receiver domains, thereby permitting regions {sigma}{sub 2} and {sigma}{sub 4} in the SL domain to open about a flexible connector loop and bind anti-{sigma} factor.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Formalism and upper limits for spin-dependent cross sections in dark matter elastic scattering with nuclei

We revise the spin-dependent neutralino-nucleus elastic scattering comparing the formalisms and approximations found in literature for the momentum transfer dependent structure functions. We argue that one of the normalized structure functions of Divari, Kosmas, Vergados, and Skouras is all that one needs to correctly take into account the detailed nuclear physics information provided by shell-model calculations. The factorization of the particle physics degrees of freedom from the nuclear physics momentum dependent structure functions implied by this formalism allows for a better understanding of the so-called model independent method for setting upper limits. We further discuss the possibility of experiments with spin-dependent sensitivity like COUPP to test or set limits on the proton spin-dependent cross section in the framework of the stau coannihilation region of the constrained minimal supersymmetric standard model. For this model with A{sub 0}=0, we provide a fitting formula by which it is possible to convert an upper limit on the spin-independent cross section as a function of the neutralino mass directly into an exclusion plot in the (m{sub 1/2}, tan{beta}) plane.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2013

Crystal Structure of the Passenger Domain of the Escherichia coli Autotransporter EspP

Autotransporters represent a large superfamily of known and putative virulence factors produced by Gram-negative bacteria. They consist of an N-terminal 'passenger domain' responsible for the specific effector functions of the molecule and a C-terminal '{beta}-domain' responsible for translocation of the passenger across the bacterial outer membrane. Here, we present the 2.5-{angstrom} crystal structure of the passenger domain of the extracellular serine protease EspP, produced by the pathogen Escherichia coli O157:H7 and a member of the serine protease autotransporters of Enterobacteriaceae (SPATEs). Like the previously structurally characterized SPATE passenger domains, the EspP passenger domain contains an extended right-handed parallel {beta}-helix preceded by an N-terminal globular domain housing the catalytic function of the protease. Of note, however, is the absence of a second globular domain protruding from this {beta}-helix. We describe the structure of the EspP passenger domain in the context of previous results and provide an alternative hypothesis for the function of the {beta}-helix within SPATEs.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Cesium Removal from AP-105 Hanford Tank Waste Using Spherical Resorcinol Formaldehyde Resin

Spherical resorcinol formaldehyde (SRF) resin is planned to be used to remove cesium (137Cs) from the aqueous phases of Hanford tank wastes in preparation for their vitrification at the Waste Treatment and Immobilization Plant. SRF is an elutable organic ion exchanger that is projected to be used in up to 30multiple process cycles (load/elute/regeneration) before being disposal . Only two full process cycles have been tested using SRF on Hanford tank waste. This paper describes the test results of six complete load/elute cycles using the SRF in a lead/lag column format with 12 liters of Hanford tank waste supernatant collected from Tank AP-105. The testing exposed the SRF to the combined sources of degradation: chemical attack from dissolved oxygen, nitric acid, and tank waste components; physical stress from resin expansion and contraction; and beta and gamma radiolytic exposure. Process conditions, dictated by Washington River Protection Solutions, featured loading until the lag column effluent reached 10% of the waste acceptance criteria (a Cs decontamination factor of 6,000). Under these conditions the lead column was nearly fully loaded and the lag column was loaded with about 20% of the input Cs. Variations in process flowrates and elution volumes were investigated as part of the testing. Characteristics examined included degradation with cycling, mass transfer zones as a function of flowrate, Cs leakage into the ensuing process cycle, and analyte mass fractionation.

spherical resorcincol formaldehyde, ion exchange, ↗
DOE OSTI2014

Comparative genomics of transcriptional regulation of methionine metabolism in proteobacteria

Methionine metabolism and uptake genes in Proteobacteria are controlled by a variety of RNA and DNA regulatory systems. We have applied comparative genomics to reconstruct regulons for three known transcription factors, MetJ, MetR, and SahR, and three known riboswitch motifs, SAH, SAM-SAH, and SAM_alpha, in ~200 genomes from 22 taxonomic groups of Proteobacteria. We also identified two novel regulons: a SahR-like transcription factor SamR controlling various methionine biosynthesis genes in the Xanthomonadales group, and a potential RNA regulatory element with terminator-antiterminator mechanism controlling the metX or metZ genes in beta-proteobacteria. For each analyzed regulator we identified the core, taxon-specific and genome-specific regulon members. By analyzing the distribution of these regulators in bacterial genomes and by comparing their regulon contents we elucidated possible evolutionary scenarios for the regulation of the methionine metabolism genes in Proteobacteria.

59 BASIC BIOLOGICAL SCIENCES↗
NASA NTRS1981

A simple model of the Lagrangian-mean flow produced by dissipating planetary waves

A simple equation for the Lagrangian-mean flow induced by damped planetary waves is derived. The flow computed for stationary planetary waves of a beta-plane is found to be generally poleward and downward during winter and appears to be about twice as strong as the diabatic circulation in the lower stratosphere. An important factor in determining the high-latitude Lagrangian-mean flow field is the subtropical jet stream which blocks planetary wave propagation toward the equatorial regions. Computations using two types of Lagrangian-mean boundary conditions at the surface show that incorrect orographic forcing distorts the Lagrangian-mean flow up to three scale heights or more above ground.

Schoeberl, M. R.↗
NASA NTRS1997

Evidence for increased beta-adrenoreceptor responsiveness induced by 14 days of simulated microgravity in humans

We studied hemodynamic responses to alpha- and beta-receptor agonists in eight healthy men before and after 14 days of 6 degrees head-down tilt (HDT) to test the hypothesis that increased adrenoreceptor responsiveness is induced by prolonged exposure to simulated microgravity. Steady-state infusions of isoproterenol (Iso) at rates of 0.005, 0.01, and 0.02 microgram.kg-1.min-1 were used to assess beta 1- and beta 2-adrenoreceptor responsiveness. Infusions of phenylephrine (PE) at rates of 0.25, 0.50, and 1.00 microgram.kg-1.min-1 were used to assess responsiveness of alpha 1-vascular adrenoreceptors. Slopes calculated from linear regressions between Iso and PE doses and changes in beat-to-beat heart rate, blood pressure, and leg vascular resistance (occlusion plethysmography) for each subject were used as an index of alpha- and beta-adrenoreceptor responsiveness. HDT increased the slopes of heart rate (1,056 +/- 107 to 1,553 +/- 83 beats micrograms-1.kg-1.min-1; P = 0.014) and vasodilation (-469 +/- 111 to -1,446 +/- 309 peripheral resistance units.microgram-1.kg-1.min-1; P = 0.0224) to Iso infusion. There was no alteration in blood pressure or vascular resistance responses to PE infusion after HDT. Our results provide evidence that simulated microgravity causes selective increases in beta 1- and beta 2-adrenoreceptor responsiveness without affecting alpha 1-vascular adrenoreceptor responses.

NASA Discipline Cardiopulmonary↗
DOE OSTI2025

Vacuum-assisted carbon molecular sieve membrane reactor for non-oxidative ethane dehydrogenation

Non-oxidative ethane dehydrogenation (EDH) is equilibrium-limited and endothermic. Selective hydrogen removal using a gas-permeable membrane within the EDH reaction zone can overcome the thermodynamic equilibrium, enabling higher ethane conversions. Employing vacuum as the permeation driving force, rather than a sweep gas, enhances the industrial viability of membrane reactors by eliminating additional post-reaction separation units. This study presents a membrane reactor that integrates H 2 -permeable carbon molecular sieve (CMS) hollow fiber membranes embedded in a fixed bed of cobalt in a dealuminated beta zeolite (Co@DeAl-BEA) catalyst, utilizing a vacuum to remove hydrogen efficiently. The CMS membrane exhibits high hydrogen permeance and an excellent H 2 /C 2 H 6 separation factor. The membrane reactor significantly enhanced the ethane conversion under reaction conditions comparable to those reported in the literature. A Langmuir-Hinshelwood kinetic rate expression was developed and incorporated into a one-dimensional steady-state reactor model. The experimentally validated model indicates that increasing the number of hollow fibers improves ethane conversion, although ethane loss to the permeate limits the benefit. The contact area between the catalyst and the membrane limits the reactor performance more than the catalytic throughput. Furthermore, we find that the location of the catalyst packing relative to the hollow fiber membranes influences ethane loss and conversion. Higher reactor pressures and inlet ethane flow rates improve space-time yield at the expense of lower ethane conversion. Increasing reactor temperature or packing length promotes both performance metrics. The EDH membrane reactor demonstrated durability over 200 h of continuous operation, maintaining record-low deactivation rates and high ethylene selectivity. Protocols for catalyst regeneration were developed.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗
DOE OSTI2016

Determinants of serum cadmium levels in a Northern Italy community: A cross-sectional study

Introduction: Cadmium (Cd) is a heavy metal and a serious environmental hazard to humans. Some uncertainties still exist about major sources of Cd exposure in non-occupationally exposed subjects in addition to cigarette smoking, such as diet and outdoor air pollution. We sought to determine the influence of these sources on a biomarker of exposure, serum Cd concentration. Methods: We recruited 51 randomly selected residents from an Italian urban community, from whom we obtained detailed information about dietary habits and smoking habits, and a blood sample for serum Cd determination. We also assessed outdoor air Cd exposure, by modeling outdoor air levels of particulate matter ≤10 µm (PM{sub 10}) from motorized traffic at geocoded subjects’ residence. Results: In crude analysis, regression beta coefficients for dietary Cd, smoking and PM10 on serum Cd levels were 0.03 (95% CI -0.83 to 0.88), 6.96 (95% CI -0.02 to 13.95) and 0.62 (95% CI -0.19 to 1.43), respectively. In the adjusted analysis, regression beta coefficients were -0.34 (95% CI -1-40 to 0.71), 5.81 (95% CI -1.43 to 13.04) and 0.47 (95% CI -0.35 to 1.29), respectively. Conclusion: Cigarette smoking was the most important factor influencing serum Cd in our non-occupationally exposed population, as expected, while dietary Cd was not associated with this biomarker. Outdoor air pollution, as assessed through exposure to particulate matter generated by motorized traffic, was an additional source of Cd exposure. - Highlights: • Smoking markedly increases serum Cd levels in non-occupationally exposed individuals. • Overall dietary Cd intake shows little association with serum Cd levels. • Air pollution from motorized traffic increases serum Cd levels.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2018

BMP2/Smad signaling pathway is involved in the inhibition function of fibroblast growth factor 21 on vascular calcification

Vascular calcification is extremely common and associated with major adverse cardiovascular events. Fibroblast growth factor (FGF) 21 has been identified as a potent metabolic regulator and a protector of the cardiovascular system. In this study, we aimed to investigate the effect of FGF21 on calcification of vascular smooth muscle cell (VSMC) and its mechanism. FGF21 inhibited beta-glycerophosphate (BGP) induced mineralization in VSMCs as determined by calcium concentration and Alizarin Red S. FGF21 suppressed BGP-induced BMP2/Smad signaling pathway components as well as osteoblast differentiation markers. FGF21 and Noggin could synergistically inhibit BGP-induced BMP2/Smad pathway expressions and calcification. Taken together, FGF21 inhibits vascular calcification in vitro by modulating BMP2/Smad signaling pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Tetrahydroxystilbene glucoside modulates amyloid precursor protein processing via activation of AKT-GSK3β pathway in cells and in APP/PS1 transgenic mice

Alternative splicing of amyloid precursor protein (APP) exon 7 generates the isoforms containing a Kunitz protease inhibitor (KPI) domain. APP-KPI levels in the brain are correlated with amyloid beta (Aβ) production. Here, we determined the effect of Tetrahydroxystilbene glucoside (TSG) on the AKT-GSK3β pathway. We found GSK3β increased APP-KPI inclusion level and interacted with the splicing factor ASF. TSG was intragastrically administered to 5-month-old APP/PS1 transgenic mice for 12 months. We found that the activated the AKT-GSK3β signaling pathway suppressed APP-KPI inclusion. Moreover, TSG treatment attenuated amyloid deposition in APP/PS1 mice. This study demonstrates the neuroprotective effect of TSG on APP expression, suggesting that TSG may be beneficial for AD prevention and treatment.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2012

5-Androstene-3{beta},17{beta}-diol Promotes Recovery of Immature Hematopoietic Cells Following Myelosuppressive Radiation and Synergizes With Thrombopoietin

Purpose: 5-Androstene-3{beta},17{beta}-diol (5-AED) stimulates recovery of hematopoiesis after exposure to radiation. To elucidate its cellular targets, the effects of 5-AED alone and in combination with (pegylated) granulocyte colony-stimulating factor and thrombopoietin (TPO) on immature hematopoietic progenitor cells were evaluated following total body irradiation. Methods and Materials: BALB/c mice were exposed to radiation delivered as a single or as a fractionated dose, and recovery of bone marrow progenitors and peripheral blood parameters was assessed. Results: BALB/c mice treated with 5-AED displayed accelerated multilineage blood cell recovery and elevated bone marrow (BM) cellularity and numbers of progenitor cells. The spleen colony-forming unit (CFU-S) assay, representing the life-saving short-term repopulating cells in BM of irradiated donor mice revealed that combined treatment with 5-AED plus TPO resulted in a 20.1-fold increase in CFU-S relative to that of placebo controls, and a 3.7 and 3.1-fold increase in comparison to 5-AED and TPO, whereas no effect was seen of Peg-G-CSF with or without 5-AED. Contrary to TPO, 5-AED also stimulated reconstitution of the more immature marrow repopulating (MRA) cells. Conclusions: 5-AED potently counteracts the hematopoietic effects of radiation-induced myelosuppression and promotes multilineage reconstitution by stimulating immature bone marrow cells in a pattern distinct from, but synergistic with TPO.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2013

Structure of a Longitudinal Actin Dimer Assembled by Tandem W Domains: Implications for Actin Filament Nucleation

Actin filament nucleators initiate polymerization in cells in a regulated manner. A common architecture among these molecules consists of tandem WASP homology 2 domains (W domains) that recruit three to four actin subunits to form a polymerization nucleus. We describe a low-resolution crystal structure of an actin dimer assembled by tandem W domains, where the first W domain is cross-linked to Cys374 of the actin subunit bound to it, whereas the last W domain is followed by the C-terminal pointed end-capping helix of thymosin {beta}4. While the arrangement of actin subunits in the dimer resembles that of a long-pitch helix of the actin filament, important differences are observed. These differences result from steric hindrance of the W domain with intersubunit contacts in the actin filament. We also determined the structure of the first W domain of Vibrio parahaemolyticus VopL cross-linked to actin Cys374 and show it to be nearly identical with non-cross-linked W-Actin structures. This result validates the use of cross-linking as a tool for the study of actin nucleation complexes, whose natural tendency to polymerize interferes with most structural methods. Combined with a biochemical analysis of nucleation, the structures may explain why nucleators based on tandem W domains with short inter-W linkers have relatively weak activity, cannot stay bound to filaments after nucleation, and are unlikely to influence filament elongation. The findings may also explain why nucleation-promoting factors of the Arp2/3 complex, which are related to tandem-W-domain nucleators, are ejected from branch junctions after nucleation. We finally show that the simple addition of the C-terminal pointed end-capping helix of thymosin {beta}4 to tandem W domains can change their activity from actin filament nucleation to monomer sequestration.

59 BASIC BIOLOGICAL SCIENCES↗