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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 1,675 records · Page 93
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

The significant effect of the thickness of Ni film on the performance of the Ni/Au Ohmic contact to p-GaN

The significant effect of the thickness of Ni film on the performance of the Ohmic contact of Ni/Au to p-GaN is studied. The Ni/Au metal films with thickness of 15/50 nm on p-GaN led to better electrical characteristics, showing a lower specific contact resistivity after annealing in the presence of oxygen. Both the formation of a NiO layer and the evolution of metal structure on the sample surface and at the interface with p-GaN were checked by transmission electron microscopy and energy-dispersive x-ray spectroscopy. The experimental results indicate that a too thin Ni film cannot form enough NiO to decrease the barrier height and get Ohmic contact to p-GaN, while a too thick Ni film will transform into too thick NiO cover on the sample surface and thus will also deteriorate the electrical conductivity of sample.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2021

First direct measurement of 59 Cu(p,α) 56 Ni: A step towards constraining the Ni-Cu cycle in the cosmos

Reactions on proton-rich nuclides drive the nucleosynthesis in core collapse supernovae (CCSNe) and in x-ray bursts (XRBs). CCSNe eject the nucleosynthesis products to the interstellar medium and hence are a potential inventory of p nuclei, whereas in XRBs nucleosynthesis powers the light curves. In both astrophysical sites the Ni-Cu cycle, which features a competition between 59 Cu(p,α) 56 Ni and 59 Cu(p,γ) 60 Zn, could potentially halt the production of heavier elements. Here, we report the first direct measurement of 59 Cu(p,α) 56 Ni using a reaccelerated 59Cu beam and a cryogenic solid hydrogen target. Furthermore, our results show that the reaction proceeds predominantly to the ground state of 56 Ni, and the experimental rate has been found to be lower than Hauser-Feshbach based statistical model predictions. New results hints that the νp process could operate at higher temperatures than previously inferred and therefore remains a viable site for synthesizing the heavier elements

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Measurement of azimuthal correlations of D mesons with charged particles in pp collisions at √s = 7 TeV and p–Pb collisions at √s NN = 5.02 TeV

The azimuthal correlations of D mesons with charged particles were measured with the ALICE apparatus in pp collisions at s = 7 &#xA0; T e V and p–Pb collisions at s N N = 5.02 &#xA0; T e V at the Large Hadron Collider. D 0 , D + , and D &#x2217;<!-- * --> + mesons and their charge conjugates with transverse momentum 3 < p T < 16 &#xA0; G e V / c and rapidity in the nucleon-nucleon centre-of-mass system | y c m s | < 0.5 (pp collisions) and &#x2212;<!-- - --> 0.96 < y c m s < 0.04 (p–Pb collisions) were correlated to charged particles with p T > 0.3 &#xA0; G e V / c . The yield of charged particles in the correlation peak induced by the jet containing the D meson and the peak width are compatible within uncertainties in the two collision systems. The data are described within uncertainties by Monte-Carlo simulations based on PYTHIA, POWHEG, and EPOS 3 event generators.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2016

Patterned growth of p-type MoS 2 atomic layers using sol-gel as precursor

2D layered MoS 2 has drawn intense attention for its applications in flexible electronic, optoelectronic, and spintronic devices. Most of the MoS 2 atomic layers grown by conventional chemical vapor deposition techniques are n-type due to the abundant sulfur vacancies. Facile production of MoS 2 atomic layers with p-type behavior, however, remains challenging. Here, a novel one-step growth has been developed to attain p-type MoS 2 layers in large scale by using Mo-containing sol–gel, including 1% tungsten (W). Atomic-resolution electron microscopy characterization reveals that small tungsten oxide clusters are commonly present on the as-grown MoS 2 film due to the incomplete reduction of W precursor at the reaction temperature. These omnipresent small tungsten oxide clusters contribute to the p-type behavior, as verified by density functional theory calculations, while preserving the crystallinity of the MoS 2 atomic layers. The Mo containing sol–gel precursor is compatible with the soft-lithography techniques, which enables patterned growth of p-type MoS 2 atomic layers into regular arrays with different shapes, holding great promise for highly integrated device applications. Lastly, an atomically thin p–n junction is fabricated by the as-prepared MoS 2 , which shows strong rectifying behavior.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Revealing the Electrophilic‐Attack Doping Mechanism for Efficient and Universal p‐Doping of Organic Semiconductors

Abstract Doping is of great importance to tailor the electrical properties of semiconductors. However, the present doping methodologies for organic semiconductors (OSCs) are either inefficient or can only apply to some OSCs conditionally, seriously limiting their general applications. Herein, a novel p‐doping mechanism is revealed by investigating the interactions between the dopant trityl tetrakis(pentafluorophenyl) borate (TrTPFB) and poly(3‐hexylthiophene) (P3HT). It is found that electrophilic attack of the trityl cations on thiophenes results in the formation of tritylated thiophenium ions, which subsequently induce electron transfer from neighboring P3HT chains to realize p‐doping. This unique p‐doping mechanism enables TrTPFB to p‐dope various OSCs including those with high ionization energy (IE ≈ 5.8 eV). Moreover, this doping mechanism endows TrTPFB with strong doping capability, leading to doping efficiency of over 80% in P3HT. The discovery and elucidation of this novel doping mechanism not only points out that strong electrophiles are a class of efficient p‐dopants for OSCs, but also provides new opportunities toward highly efficient doping of various OSCs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Spectral, Electrochemical and Computational Investigations of Binding of n-(4-Hydroxyphenyl)-imidazole with p-Sulfonatocalix[4]arene

The interaction of n-(4-hydroxyphenyl)-imidazole with p-sulfonatocalix[4]arene is studied using fluorescence technique. The quenching of fluorescence intensity explains the efficiency of binding via binding constant and quenching constant. The excited state lifetime of n-(4-hydroxyphenyl)-imidazole is decreased upon interaction with p-sulfonatocalix[4]arene. The cyclic voltametric studies emphasized the interaction of n-(4-hydroxyphenyl)-imidazole with p-sulfonatocalix[4]arene. Quantum chemical calculations are carried out to study the interactions as well as charge transfer between the host and the guest upon complexation. The simulations revealed that the n-(4-hydroxyphenyl)-imidazole interacts with p-sulfonatocalix[4]arene with horizontal orientation with in the p-sulfonatocalix[4]arene cavity.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2018

On the Ultrasolvability of p-Extensions of an Abelian Group by a Cyclic Kernel

The paper contains a solution of A. V. Yakovlev’s problem in the embedding theory for p-extensions of odd order with a cyclic normal subgroup and an Abelian quotient group: for such nonsplit extensions there exists a realization for the quotient group as a Galois group over number fields such that the corresponding embedding problem is ultrasolvable (i.e., this embedding problem is solvable and has only fields as solutions). A solution for embedding problems of p-extensions of odd order with kernel of order p and with a quotient group that is represented by a direct product of its proper subgroups is also given – this is a generalization for p > 2 of an analogous result for p = 2 due to A. Ledet.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2015

Production of ⁶¹Cu by the nat Zn(p,α) reaction: Improved separation and specific activity determination by titration with three chelators

In this study, the cyclotron-based production of position-emitting ⁶¹Cu using the (p,α) reaction at 11.7 MeV was investigated starting from natural-zinc ( nat Zn) and enriched ⁶⁴Zn-foil targets, as well as its subsequent purification. For nat Zn, a combination of three resins were assessed to separate ⁶¹Cu from contaminating 66,67,68 Ga and nat Zn. The specific activity of the purified ⁶¹Cu determined using ICP-MS analysis ranged from 143.3±14.3(SD) to 506.2±50.6 MBq/μg while the titration method using p-SCN-Bn-DOTA, p-SCN-Bn-NOTA and diamsar gave variable results (4.7±0.2 to 412.5±15.3 MBq/μg), with diamsar lying closest to the ICP-MS values. Results suggest that the p-SCN-Bn-DOTA and p-SCN-Bn-NOTA titration methods are significantly affected by the presence of trace-metal contaminants.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2017

mir-67 regulates P. aeruginosa avoidance behavior in C. elegans

Highlights: • The MicroRNA mir-67 expression is up-regulated after a pathogenic bacterium P. aeruginosa infection. • mir-67 regulates P. aeruginosa avoidance behavior by inhibiting SAX-7 expression. • The mir-67-SAX-7 signaling is independent on the known signaling pathways that regulate pathogen avoidance. Pathogen avoidance behaviors are found throughout the animal kingdom and are important for animal's survival in nature. As a free-living nematode, C. elegans is exposed to a variety of microorganisms, including toxic or pathogenic bacteria, in soil. C. elegans can develop efficient avoidance responses to pathogenic bacteria to minimize the infection risk. However, the role of microRNAs (miRNAs) in pathogen avoidance in C. elegans remains unclear. In this report, we showed that the miRNA mir-67 was involved in a behavioral avoidance response to P. aeruginosa PA14. Exposure to P. aeruginosa PA14 induced the expression of mir-67 in worms. mir-67(n4899) mutants exhibited a reduced ability to avoid P. aeruginosa PA14. By combining quantitative proteomic analysis with miRNA target prediction algorithms, we identified SAX-7/L1CAM, which is transmembrane cell adhesion receptor molecule, as the target of mir-67. Silencing of sax-7 by RNAi on mir-67 mutants rescued avoidance behavioral. Our data demonstrate that the mir-67-SAX-7 pathway modulate the behavioral avoidance response to pathogens, thus providing a new perspective in the role of miRNAs in host–microbe interactions.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

A novel circular RNA, hsa{sub c}irc{sub 0}046701, promotes carcinogenesis by increasing the expression of miR-142-3p target ITGB8 in glioma

Highlights: • We identified a novel circular RNA, hsa{sub c}irc{sub 0}046701 in glioma cells. • Hsa{sub c}irc{sub 0}046701 was significantly upregulated in glioma tissues. • Hsa{sub c}irc{sub 0}046701 sponges miR-142-3p in glioma. • MiR-142-3p directly targets ITGB8 in glioma. • Hsa{sub c}irc{sub 0}046701/miR-142-3p/ITGB8 axis plays critical roles in glioma pathogenesis. In the present study, we identified a novel circular RNA (circRNA), hsa{sub c}irc{sub 0}046701, in glioma cells. We measured the expression of hsa{sub c}irc{sub 0}046701 using qRT-PCR in glioma tissues and cell lines, and explored its functions using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, colony formation, and Transwell assays. Luciferase reporter assays were performed to validate the correlation between microRNA miR-142-3p and hsa{sub c}irc{sub 0}046701 or integrin subunit beta 8 (ITGB8). The results showed that hsa{sub c}irc{sub 0}046701 was significantly upregulated in glioma tissues and cell lines, and knockdown of hsa{sub c}irc{sub 0}046701 inhibited cell proliferation and invasion. Luciferase reporter assays indicated that hsa{sub c}irc{sub 0}046701 functions as a sponge for miR-142-3p and regulates the expression of ITGB8. Subsequently, functional assays revealed that silencing of hsa{sub c}irc{sub 0}046701 could upregulate miR-142-3p, resulting in downregulation of ITGB8. The results demonstrated that the hsa{sub c}irc{sub 0}046701/miR-142-3p/ITGB8 axis might play critical regulatory roles in the pathogenesis and development of glioma.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

miR-126-5p targets Malate Dehydrogenase 1 in non-small cell lung carcinomas

Highlights: • A microRNA (miR) screen identified 3 binding sites of miR-126-5p in the 3′UTR of MDH1. • miR-126 and MDH1 are inversely correlated in large primary cohorts of NSCLCs. • miR-126 can reduce the protein level of MDH1, while sparing its isoenzyme MDH2. • miR-126-5p inhibits the MDH1 enzymatic activity and mitochondrial respiration. • miR-126-5p exerts cytostatic and cytotoxic effects in NSCLCs. Malate Dehydrogenase (MDH) 1 has recently been shown to be highly expressed and display prognostic value in non-small cell lung carcinomas (NSCLCs). However, it is not known how MDH1 expression is regulated and there is no current molecular or chemical strategy that specifically targets MDH1. This may be due to structural and enzymatic similarities with its isoenzyme, malate dehydrogenase 2 (MDH2). However, MDH1 and MDH2 are encoded by distinct genes and this opens up the possibility for modulation at the expression level. Here, we screened in silico for microRNAs (miRs) that selectively targets the 3′UTR region of MDH1. These analyses revealed that mir-126-5p has three binding sites in the 3′UTR region of MDH1. Additionally, we show that expression of miR-126-5p suppresses the enzymatic activity of MDH1, mitochondrial respiration and caused cell death in NSCLC cell lines.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Serum extracellular vesicles promote proliferation of H9C2 cardiomyocytes by increasing miR-17-3p

Highlights: • Serum extracellular vesicles promotes H9C2 cardiomyocytes proliferation. • miR-17-3p mediates the pro-proliferation effects. • TIMP3 is a target gene of miR-17-3p. Emerging evidence showed that cardiac proliferation played a significant role in the cardiac rehabilitation and repair. Extracellular vesicles (EVs) are known to regulate multiple cell functions, whereas the role of EVs in cardiac proliferation still remains unclear. In this study, we found that serum EVs promoted cell proliferation in rat heart myoblastic H9C2 cells with significantly increased expression level of miR-17-3p. Inhibition of miR-17-3p could decrease H9C2 cells proliferation induced by serum EVs. Additionally, we found that TIMP3 was a target of miR-17-3p in H9C2 cells proliferation and the expression of TIMP3 was downregulated by serum EVs. Meanwhile, inhibition of TIMP3 increased cardiac proliferation. In conclusion, results of our study indicated that serum EVs could promote the proliferation of H9C2 cells via regulating miR-17-3p/TIMP3, which may be a potential therapeutic target for treatment of cardiac injury.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

Circular RNA hsa{sub c}irc{sub 0}000673 promotes hepatocellular carcinoma malignance by decreasing miR-767-3p targeting SET

Highlights: • Hsa{sub c}irc{sub 0}000673 was highly expressed in HCC tissues. • Hsa{sub c}irc{sub 0}000673 knockdown suppressed HCC cell proliferation and invasion. • Hsa{sub c}irc{sub 0}000673 promoted HCC proliferation and invasion by sponging miR-767-3p. • Hsa{sub c}irc{sub 0}000673 facilitated HCC cell proliferation and invasion via regulating miR-767-3p/SET pathway. The importance of circular RNAs (circRNAs) in human cancers has gradually been acknowledged. In hepatocellular carcinoma (HCC), several circRNAs have been reported to regulate tumor growth and metastasis. However, the role of hsa{sub c}irc{sub 0}000673 in HCC remains largely unknown. In this study, we found that hsa{sub c}irc{sub 0}000673 was significantly upregulated in HCC tissues compared to adjacent non-tumor tissues. Moreover, we found that hsa{sub c}irc{sub 0}000673 knockdown markedly inhibited the proliferation and invasion of HCC cells in vitro. Besides, hsa{sub c}irc{sub 0}000673 silence led to delayed tumor growth in vivo. In terms of mechanism, we showed that hsa{sub c}irc{sub 0}000673 directly associated with miR-767-3p in HCC cells. Via inhibiting miR-767-3p, hsa{sub c}irc{sub 0}000673 promoted HCC cell proliferation and invasion. Furthermore, we demonstrated that SET was a downstream effector of hsa{sub c}irc{sub 0}000673/miR-767-3p signaling. We showed that miR-767-3p could significantly promote SET expression by sponging miR-767-3p in HCC cells. Finally, rescue assays indicated that SET expression was essential for the effects of hsa{sub c}irc{sub 0}000673/miR-767-3p signaling on HCC cell proliferation and invasion. Taken together, our findings demonstrated that hsa{sub c}irc{sub 0}000673 promoted HCC malignant behaviors via regulating miR-767-3p/SET pathway.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

MiR-139-5p suppresses osteosarcoma cell growth and invasion through regulating DNMT1

Highlights: • MiR-139-5p suppresses the migration and invasion of osteosarcoma cell lines. • MiR-139-5p decreases DNMT1 expressions in osteosarcoma lines. • MiR-139-5p reduces the osteosarcoma cell migration and invasion by regulating DNMT1 and suppresses osteosarcoma tumor growth in vivo. Accumulating evidence has suggested the crucial roles of differentially expressed miRNAs in osteosarcoma progression. MiR-139-5p was decreased in various cancers. However, the role of miR-139-5p in the development of osteosarcoma and the underlying mechanism remain to be addressed.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

T2DM inhibition of endothelial miR-342-3p facilitates angiogenic dysfunction via repression of FGF11 signaling

Understanding the function and molecular relevance of distinct miRNAs in endothelial cells (ECs) paves avenues for possible therapeutic intervention by targeting epigenetic mechanisms in vascular endothelial dysfunction, one of the major complications of type 2 diabetes mellitus (T2DM). MiR-342-3p, an obesity-associated miRNA, has recently been shown to be significantly upregulated in human angiosarcoma compared to benign hemangioma, indicating its potential involvement as a proangiogenic factor. Herein, we show that endothelial miR-342-3p expression was significantly compromised in T2DM organisms and this inhibition powerfully blocked vasculogenesis in vivo by repressing endothelial proliferation and migration. From a mechanistic standpoint, miR-342-3p promoted the transactivation of fibroblast growth factor 11 (FGF11) by directly targeting its 3′ untranslated regions (3′UTRs). Functionally, overexpression of exogenous FGF11 successfully rescued miR-342-3p deficiency-impaired endothelial proliferation and migration. Thus, perturbation of miR-342-3p/FGF11 cascade by hyperinsulinemia plays a causative role in the induction of vascular dysfunction in T2DM. Overall, the current study underscore an endothelial facet of miR-342-3p, which may operate as a novel epigenetic integrator linking adipogenic homeostasis and angiogenesis.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2018

p-Coumaric acid stimulates longitudinal bone growth through increasing the serum production and expression levels of insulin-like growth factor 1 in rats

The aim of the present study was to examine the effects of p-coumaric acid on the longitudinal growth of the long bone in adolescent male rats. Teatment with p-coumaric acid significantly increased the tibial length and the height of each growth plate zone and the ratio of 5-bromo-2′-deoxyuridine-positive cells relative to total proliferative cells. Expression of insulin-like growth factor 1 and its receptor in the proliferative and hypertrophic zones, and serum levels of growth hormone and insulin-like growth factor 1 were significantly increased as well in the p-coumaric acid-treated group. Via increasing both the serum level of insulin-like growth factor 1 and its expression, p-coumaric acid could promote cell proliferation in growth plate zones. These results suggest that p-coumaric acid has the potential to increase height and may be a feasible alternative to growth hormone therapy.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2017

Thermodynamic and kinetic modeling of grain boundary equilibrium segregation of P in α-Fe

Phosphorus is a primary contributor to interface fracture and embrittlement in steels because of its strong segregation tendency at grain boundaries (GBs). The lack of consistency in literature data imposes great difficulties in performing segregation modeling that is compatible with both the Langmuir-Mclean segregation theory and the thermodynamic description of the Bcc(Fe,P) phase. Our work carefully evaluated experimental data for phosphorus segregation at GBs in -Fe and provided a new formula for converting the auger electron spectroscopy (AES) peak height ratio to GBs. Furthermore, based on newly assessed literature data, this work proposes that the major driving force for phosphorus segregation is the formation of Fe 3 P-type clusters at GBs, which is supported not only by the almost equivalent Gibbs energy of _Fe using the Bcc(Fe,P) substitutional model and the Bcc(Fe,Fe 3 P, P) associate model, but also by the good agreement between thermodynamic/kinetic modeling results and experimental data.

36 MATERIALS SCIENCE↗