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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 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

Metformin inhibits epithelial–mesenchymal transition in prostate cancer cells: Involvement of the tumor suppressor miR30a and its target gene SOX4

Highlights: • Metformin inhibits TGF-β-induced EMT in prostate cancer (PCa) cells. • Metformin upregulates tumor suppressor miR30a and downregulates SOX4 in PCa cells. • SOX4 is a target gene of miR30a. - Abstract: Tumor metastasis is the leading cause of mortality and morbidity of prostate cancer (PCa) patients. Epithelial–mesenchymal transition (EMT) plays a critical role in cancer progression and metastasis. Recent evidence suggested that diabetic patients treated with metformin have lower PCa risk and better prognosis. This study was aimed to investigate the effects of metformin on EMT in PCa cells and the possible microRNA (miRNA)-based mechanisms. MiRNAs have been shown to regulate various processes of cancer metastasis. We herein showed that metformin significantly inhibits proliferation of Vcap and PC-3 cells, induces G0/G1 cell cycle arrest and inhibits invasiveness and motility capacity of Vcap cells. Metformin could inhibit TGF-β-induced EMT in Vcap cells, as manifested by inhibition of the increase of N-cadherin (p = 0.013), Vimentin (p = 0.002) and the decrease of E-cadherin (p = 0.0023) and β-catenin (p = 0.034) at mRNA and protein levels. Notably, we demonstrated significant upregulation of miR30a levels by metformin (P < 0.05) and further experiments indicated that miR30a significantly inhibits proliferation and EMT process of Vcap cells. Interestingly, we identified that SOX4, a previously reported oncogenic transcriptional factor and modulator of EMT, is a direct target gene of miR30a. Finally, we screened the expression of miR30a and SOX4 in 84 PCa cases with radical prostatectomy. Of note, SOX4 overexpression is significantly associated with decreased levels of miR30a in PCa cases. In all, our study suggested that inhibition of EMT by metformin in PCa cells may involve upregulation of miR30a and downregulation of SOX4.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Structural chemistry and magnetic properties of Y{sub 2}CoGe{sub 4}O{sub 12}

Polycrystalline Y{sub 2}CoGe{sub 4}O{sub 12} has been prepared by standard ceramic methods. The crystal structure (space group P4/nbm; a=9.8465(2), c=4.92986(9) Å) consists of metal-rich layers separated from each other by Ge{sub 4}O{sub 12} groups comprised of four corner-sharing GeO{sub 4} tetrahedra. Two cation sites lie within the layers; an eight-coordinate site occupied by yttrium and a six-coordinate site occupied by a 1:1 disordered distribution of yttrium and cobalt. Neutron diffraction revealed two-fold disorder on the oxide sublattice; this has been elucidated using Co K-edge EXAFS spectroscopy. The availability of two sites allows each oxide ion to accommodate the coordination preferences of its single Co/Y neighbour; the GeO{sub 4} tetrahedra distort to absorb any consequent strain. The octahedron of anions around each Co{sup 2+} cation shows a pseudo-tetragonal distortion with a strain (Co–O){sub eq}–(Co–O){sub ax}/(Co–O){sub eq}=−0.173. This results in an unusually large effective magnetic moment of 6.05 µ{sub B} per Co{sup 2+} cation. - Graphical abstract: A distorted coordination environment leads to an unusually large effective magnetic moment of Co{sup 2+} in Y{sub 2}CoGe{sub 4}O{sub 12}. - Highlights: • Co{sup 2+} and Y{sup 3+} occupy the same site in a disordered manner. • Distorted coordination geometry around Co{sup 2+} results in an unusually large effective magnetic moment. • Use of neutron diffraction and EXAFS to probe average structure and local structure, respectively.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Structural, vibrational and photoluminescence properties of Sr{sub (1-x)}Pb{sub x}MoO{sub 4} solid solution synthesized by solid state reaction

Highlights: • The solid solution Sr{sub (1-x)}Pb{sub (x)}MoO{sub 4} is characterized by X-ray diffraction. • Raman spectroscopy confirm that the solid solution is disordered. • Photoluminescence experiments are carried out under X-ray excitation. • Emission bands can be decomposed into four components between 2.1 and 2.9 eV. • The intensities of emission bands reach a maximum for 0.1 < x < 0.4. - Abstract: In this paper, strontium lead molybdate Sr{sub 1-x}Pb{sub x}MoO{sub 4} polycrystalline samples with 0 ≤ x ≤ 1 were prepared by solid state preparation method at 1000 °C. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and micro-Raman spectroscopy. Their photoluminescence responses were analyzed under X-ray excitation. Rietveld refinements indicate that all the materials present a scheelite-type tetragonal structure. Micro-Raman spectra confirmed the formation of the solid solution with a specific effect due to Sr-O-Mo and Pb-O-Mo links in the scheelite structure. SEM images showed modifications in the shapes and grain sizes as x increased. Broad photoluminescent emission bands were observed in the energy range 2.1–2.9 eV. The emission bands were decomposed into four gaussian components. The intensities of all components presented a strong maximum in the composition range 0.1 < x < 0.4.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Self-assembled hierarchical Sn3O4-multi-wall carbon nanotubes: Facile fabrication, promoted charge separation, and enhanced photocatalytic performances

Highlights: • Controlled self-assembly of Sn{sub 3}O{sub 4} nanoflakes over CNTs was achieved. • The SO-CNT-4 hybrid exhibits the best activity under visible light. • Promoted charge separation efficiency lead to the activity enhancement. - Abstract: Controlled assembling of Sn{sub 3}O{sub 4} nanoflakes over multi-wall carbon nanotubes (CNTs) was achieved for the first time by using a facile hydrothermal method. The SEM and TEM images showed that numerous Sn{sub 3}O{sub 4} nanoflakes were widely assembled over the surface of CNTs. In these hybrids, the CNTs served as dispersing-template could reduce the agglomeration of Sn{sub 3}O{sub 4} nanoflakes, as well as facilitate the interfacial charge transfer because of its high electrical conductivity. The Sn{sub 3}O{sub 4}-CNTs photocatalysts have exhibited remarkably promoted performances in decomposing organic contaminant under visible or solar light. The Sn{sub 3}O{sub 4}-CNTs hybrid with CNTs mass ratio of 4.37% exhibited the best activity under visible light, while that with CNTs mass ratio of 1.41% was more efficient when irradiated by solar light, the activity of which was about 3.47 times higher than that of pristine Sn{sub 3}O{sub 4} under identical conditions. Controlled experiments proved that O{sub 2}{sup −} and h{sup +} played the chief role in decomposing organic pollutants.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2022

How Does Flow Alteration Propagate Across a Large, Highly Regulated Basin? Dam Attributes, Network Context, and Implications for Biodiversity

Abstract Large dams are a leading cause of river ecosystem degradation. Although dams have cumulative effects as water flows downstream in a river network, most flow alteration research has focused on local impacts of single dams. Here we examined the highly regulated Colorado River Basin (CRB) to understand how flow alteration propagates in river networks, as influenced by the location and characteristics of dams as well as the structure of the river network—including the presence of tributaries. We used a spatial Markov network model informed by 117 upstream‐downstream pairs of monthly flow series (2003–2017) to estimate flow alteration from 84 intermediate‐to‐large dams representing >83% of the total storage in the CRB. Using Least Absolute Shrinkage and Selection Operator regression, we then investigated how flow alteration was influenced by local dam properties (e.g., purpose, storage capacity) and network‐level attributes (e.g., position, upstream cumulative storage). Flow alteration was highly variable across the network, but tended to accumulate downstream and remained high in the main stem. Dam impacts were explained by network‐level attributes (63%) more than by local dam properties (37%), underscoring the need to consider network context when assessing dam impacts. High‐impact dams were often located in sub‐watersheds with high levels of native fish biodiversity, fish imperilment, or species requiring seasonal flows that are no longer present. These three biodiversity dimensions, as well as the amount of dam‐free downstream habitat, indicate potential to restore river ecosystems via controlled flow releases. Our methods are transferrable and could guide screening for dam reoperation in other highly regulated basins.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

A combined experimental and computational study on the reaction dynamics of the 1-propynyl (CH 3 CC, X 2 A 1 ) – propylene (CH 3 CHCH 2 , X 1 A') system: formation of 1,3-dimethylvinylacetylene (CH 3 CCCHCHCH 3 , X 1 A') under single collision conditions

The reaction of the 1-propynyl radical (CH 3 CC; X 2 A 1 ) with propylene (CH 3 CHCH 2 ; X 1 A') was studied in a crossed molecular beam machine at a collision energy of 37 ± 1 kJ mol –1 . Experimental data combined with high-level electronic structure (CCSD(T)-F12/cc-pVTZ-F12//ωB97X-D/6-311G(d,p)) and RRKM calculations reveal the reaction mechanism. Here, the overall barrierless and exoergic reaction involves indirect reaction dynamics and commences preferentially with addition of 1-propynyl with its radical centre to the carbon–carbon double bond at the terminal carbon atom of propylene. This work focuses on molecular mass growth process (hydrogen loss channels) although theory suggests methyl loss as a prevalent channel. In these processes, the C6H9 collision complexes either emit atomic hydrogen or undergo isomerisation followed by atomic hydrogen loss to preferentially yield the cis/trans isomers of 1,3-dimethylvinylacetylene (2-hexen-4-yne) as the primary product. Analysis of reaction dynamics of 1-propynyl and ethynyl radicals with propylene along with their fractional abundance in deep space suggests formation of methyl- and dimethyl derivatives of vinylacetylene in cold molecular clouds. Once formed they may engage in fundamental molecular mass growth processes via the barrierless Hydrogen Abstraction Vinylacetylene Addition mechanism that leads to the formation of methyl- and dimethylnaphthalenes thus providing a versatile route to methyl-substituted PAHs in interstellar medium.

1-propynyl↗
DOE OSTI2024

Can socio-economic indicators of vulnerability help predict spatial variations in the duration and severity of power outages due to tropical cyclones?

Abstract Tropical cyclones are the leading cause of major power outages in the U.S., and their effects can be devastating for communities. However, few studies have holistically examined the degree to which socio-economic variables can explain spatial variations in disruptions and reveal potential inequities thereof. Here, we apply machine learning techniques to analyze 20 tropical cyclones and predict county-level outage duration and percentage of customers losing power using a comprehensive set of weather, environmental, and socio-economic factors. Our models are able to accurately predict these outage response variables, but after controlling for the effects of weather conditions and environmental factors in the models, we find the effects of socio-economic variables to be largely immaterial. However, county-level data could be overlooking effects of socio-economic disparities taking place at more granular spatial scales, and we must remain aware of the fact that when faced with similar outage events, socio-economically vulnerable communities will still find it more difficult to cope with disruptions compared to less vulnerable ones.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗
DOE OSTI2024

OzDES Reverberation Mapping Program: Stacking analysis with Hβ, Mg ii , and C iv

ABSTRACT Reverberation mapping is the leading technique used to measure direct black hole masses outside of the local Universe. Additionally, reverberation measurements calibrate secondary mass-scaling relations used to estimate single-epoch virial black hole masses. The Australian Dark Energy Survey (OzDES) conducted one of the first multi-object reverberation mapping surveys, monitoring 735 AGN up to z ∼ 4, over 6 years. The limited temporal coverage of the OzDES data has hindered recovery of individual measurements for some classes of sources, particularly those with shorter reverberation lags or lags that fall within campaign season gaps. To alleviate this limitation, we perform a stacking analysis of the cross-correlation functions of sources with similar intrinsic properties to recover average composite reverberation lags. This analysis leads to the recovery of average lags in each redshift-luminosity bin across our sample. We present the average lags recovered for the Hβ, Mg ii, and C iv samples, as well as multiline measurements for redshift bins where two lines are accessible. The stacking analysis is consistent with the Radius–Luminosity relations for each line. Our results for the Hβ sample demonstrate that stacking has the potential to improve upon constraints on the R–L relation, which have been derived only from individual source measurements until now.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2025

CpoS-Inc interactions facilitate host cell modulation during Chlamydia trachomatis infection

ABSTRACT Chlamydia trachomatis ( C.t .), the leading bacterial cause of sexually transmitted infections, replicates within a unique intracellular compartment called the inclusion, which is modified by secreted proteins known as inclusion membrane (Inc) proteins. Here, we further characterize CpoS, an Inc protein previously shown to be critical for bacterial replication and inclusion development. We demonstrate that CpoS directly binds multiple coiled-coil region-containing Incs and engages Rab GTPases at a separate site. Notably, CpoS-InaC interactions facilitate the recruitment of select Arf GTPases to the inclusion membrane, while Rab recruitment occurs independently of these interactions. Biochemical and biophysical analyses revealed that Incs self-oligomerize to form higher-ordered structures, with CpoS adopting a tetrameric conformation resembling that of eukaryotic SNARE proteins. We propose that these assemblies serve as scaffolds to orchestrate vesicle docking, tethering, and fusion. Our findings highlight the intricate interplay between bacterial and host factors, revealing how C.t . leverages both Inc-Inc interactions and host protein engagement to manipulate vesicular trafficking and sustain infection.

Tijerina, Xavier [Department of Microbiology and I↗
DOE OSTI2023

Campylobacter jejuni uses energy taxis and a dehydrogenase enzyme for l -fucose chemotaxis

ABSTRACT Campylobacter jejuni is a leading cause of bacterial diarrhea worldwide, and infection in infants is associated with growth stunting in low- and middle-income countries. Approximately half of all C. jejuni isolates are asaccharolytic, while the remainder encode enzymes capable of l -fucose catabolism. Our previous study suggested that breastfed infants originating from sub-Saharan Africa and South Asia were colonized less frequently with l -fucose-metabolizing C. jejuni isolates compared to asaccharolytic strains. We also showed that FucX is an l -fucose dehydrogenase that binds to its NADP + cofactor even in the absence of l -fucose and that this enzyme is sufficient for l -fucose chemotaxis when introduced into strains lacking the metabolic pathway. This study indicates that FucX may influence l -fucose chemotaxis by increasing cellular NADPH/NADP + ratios, which subsequently affect the energy taxis components, CetABC that respond to shifting gradients of electron acceptors and donors. Furthermore, C. jejuni CetAB and CetAC can complement Escherichia coli aerotaxis. Our data support a model in which the shift in NADP + levels, impacted by the FucX dehydrogenase, affects chemotaxis in response to l -fucose. This swimming behavior can be phenocopied with a homologous l -fucose dehydrogenase from Burkholderia multivorans . Taken together, our work provides a possible explanation for why l -fucose-metabolizing C. jejuni isolates swim away from intestinal epithelial cells toward free fucose in the lumen where they are subsequently cleared by breastfed infants. IMPORTANCE In this study, we identify a separate role for the Campylobacter jejuni l -fucose dehydrogenase in l -fucose chemotaxis and demonstrate that this mechanism is not only limited to C. jejuni but is also present in Burkholderia multivorans . We now hypothesize that l -fucose energy taxis may contribute to the reduction of l -fucose-metabolizing strains of C. jejuni from the gastrointestinal tract of breastfed infants, selecting for isolates with increased colonization potential.

59 BASIC BIOLOGICAL SCIENCES↗