Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “MASS SPECTRA”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 991 records · Page 55
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Aging Enhances the Production of Reactive Oxygen Species and Bactericidal Activity in Peritoneal Macrophages by Upregulating Classical Activation Pathways

Maintenance of macrophages in their basal state and their rapid activation in response to pathogen detection are central to the innate immune system, acting to limit nonspecific oxidative damage and promote pathogen killing following infection. To identify possible age-related alterations in macrophage function, we have assayed the function of peritoneal macrophages from young (3–4 months) and aged (14–15 months) Balb/c mice. In agreement with prior suggestions, we observe age-dependent increases in the extent of recruitment of macrophages into the peritoneum, as well as ex vivo functional changes involving enhanced nitric oxide production under resting conditions that contribute to a reduction in the time needed for full activation of senescent macrophages following exposure to lipopolysaccharides (LPS). Further, we observe enhanced bactericidal activity following Salmonella uptake by macrophages isolated from aged Balb/c mice in comparison with those isolated from young animals. Pathways responsible for observed phenotypic changes were interrogated using tandem mass spectrometry, which identified age-dependent increases in levels of proteins linked to immune cell pathways under basal conditions and following LPS activation. Immune pathways upregulated in macrophages isolated from aged mice include proteins critical to the formation of the immunoproteasome. Detection of these latter proteins is dramatically enhanced following LPS exposure for macrophages isolated from aged animals; in comparison, the identification of immunoproteasome subunits is insensitive to LPS exposure for macrophages isolated from young animals. Consistent with observed global changes in the proteome, quantitative proteomic measurements indicate that there are age-dependent abundance changes involving specific proteins linked to immune cell function under basal conditions. LPS exposure selectively increases the levels of many proteins involved in immune cell function in aged Balb/c mice. Collectively, these results indicate that macrophages isolated from old mice are in a preactivated state that enhances their sensitivities to LPS exposure. The hyper-responsive activation of macrophages in aged animals may act to minimize infection by general bacterial threats that arise due to age-dependent declines in adaptive immunity. Finally, however, this hypersensitivity and the associated increase in the level of formation of reactive oxygen species are likely to contribute to observed age-dependent increases in the level of oxidative damage that underlie many diseases of the elderly.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

PECAN: library-free peptide detection for data-independent acquisition tandem mass spectrometry data

Data-independent acquisition (DIA) is an emerging mass spectrometry (MS)-based technique for unbiased and reproducible measurement of protein mixtures. DIA tandem mass spectrometry spectra are often highly multiplexed, containing product ions from multiple cofragmenting precursors. Detecting peptides directly from DIA data is therefore challenging; most DIA data analyses require spectral libraries. Here we present PECECAN (http://pecan.maccosslab.org), a library-free, peptide-centric tool that robustly and accurately detects peptides directly from DIA data. PECECAN reports evidence of detection based on product ion scoring, which enables detection of low-abundance analytes with poor precursor ion signal. We demonstrate the chromatographic peak picking accuracy and peptide detection capability of PECECAN, and we further validate its detection with data-dependent acquisition and targeted analyses. Lastly, we used PECECAN to build a plasma proteome library from DIA data and to query known sequence variants.

96 KNOWLEDGE MANAGEMENT AND PRESERVATION↗
DOE OSTI2021

Metabolite discovery through global annotation of untargeted metabolomics data

Liquid chromatography–high-resolution mass spectrometry (LC-MS)-based metabolomics aims to identify and quantify all metabolites, but most LC-MS peaks remain unidentified. Here we present a global network optimization approach, NetID, to annotate untargeted LC-MS metabolomics data. The approach aims to generate, for all experimentally observed ion peaks, annotations that match the measured masses, retention times and (when available) tandem mass spectrometry fragmentation patterns. Peaks are connected based on mass differences reflecting adduction, fragmentation, isotopes, or feasible biochemical transformations. Global optimization generates a single network linking most observed ion peaks, enhances peak assignment accuracy, and produces chemically informative peak–peak relationships, including for peaks lacking tandem mass spectrometry spectra. Applying this approach to yeast and mouse data, we identified five previously unrecognized metabolites (thiamine derivatives and N-glucosyl-taurine). Isotope tracer studies indicate active flux through these metabolites. Furthermore, NetID applies existing metabolomic knowledge and global optimization to substantially improve annotation coverage and accuracy in untargeted metabolomics datasets, facilitating metabolite discovery.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2010

Diffractive Pion Dissociation into {pi}{sup -{pi}+{pi}-{pi}+{pi}-} at COMPASS

At the COMPASS experiment a sample of {approx}380000 exclusive events of diffractive pion dissociation on a lead target into a {pi}{sup -{pi}+{pi}-{pi}+{pi}-} final state has been recorded in 2004. The 5{pi} invariant mass spectrum shows a momentum transfer dependent structure peaking around 1.8 GeV/c{sup 2}. In the (4{pi}){sup 0} subsystem there is a clear signal for the f{sub 1}(1285) resonance decaying into 4 pions. In this note we describe the data sample and explore the physics potential of this final state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

The three-body structure of the X(2175) and the Y(4260) states

In this talk, I discuss our study of three-meson systems where we find dynamical generation of two resonances: the X(2175) and the Y(4260). Experimentally, the former one has been found in the mass spectrum of the {phi}f{sub 0}(980) system and the latter one in that of the J/{Psi}{pi}{pi} system. Our study of these systems, using the Faddeev equations, reveals that these resonances possess a three-body structure.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

A Novel View of Exotic Hadrons and the Covariant U-tilde(12)-Classification Scheme

I classify exotic hadrons into two types, 'genuine' and 'hidden' exotics, and propose that the 'hidden' exotics would be interpreted as 'chiralons' in the U-tilde(12){sub SF}xO(3,1){sub L}-classification scheme of hadrons. Based upon this conjecture I investigate the mass spectrum of 1S, 1P, and 2S states for the cc-bar system by use of a phenomenological mass formula with the spin-dependent interactions and present possible assignments for exotic neutral charmonium-like states which were recently discovered. It is also mentioned that some J{sup PC}-exotic states predicted in this scheme might correspond to those found in a recent lattice QCD calculation of the charmonium spectrum.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Study of central production of charged pionic modes at COMPASS

The COmmon Muon and Proton Apparatus for Structure and Spectroscopy is a fixed target experiment at the CERN SPS accelerator. In the years 2008 and 2009 the collaboration focused on hadron spectroscopy: data with hadronic beams at a momentum of 190 GeV/c impinging on hydrogen, lead, nickel and tungsten targets were taken. In the preparation for this run-time, the apparatus was adapted to measure the formation of resonances by both diffractive scattering and central production. In the latter case, the study of charged pionic channels is well-suited to search for members of the f{sub 0} particle family, including some of the glueball candidates. The analysis of the newly taken data has started, these proceedings are meant to give a status and overview of the current activities.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Experimental issues on K{sup -} absorption by few nucleons and the search for Bound Kaonic Nuclear Systems

The available experimental data on K{sup -} absorption on nuclei are rather old and scarce and cannot help very much to understand whether the formation of composite objects made by kaons and many nucleons can occur. The existence of such structures is suggested by a few theoretical models, but many others do not expect them--or at least consider their experimental observation very difficult. The experimental study of their existence is based on the observation of hyperon-nucleon correlations, and on the features of the {Lambda}p(d,t) invariant mass distributions. If existing, in fact, these aggregates should non-mesonically decay in hyperon-nucleons final states, being the pionic channels forbidden due to energy conservation. Complementary information may also be gathered by the study of missing mass distributions.Recent experiments restarted the study of K{sup -}A absorption in light nuclei, namely on {sup 4}He by KEK-E549, and on {sup 6,7}Li, {sup 9}Be and {sup 12}C by FINUDA at DA{Phi}NE.The experimental results obtained so far by the various experiments studying the K{sup -} absorption in nuclei are here summarized and presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

A search for deeply bound kaonic nuclear states at J-PARC

J-PARC E15 experiment aims to search for the lightest kaonic nuclei, namely K{sup -}pp bound states, using in-flight (K{sup -}, n) reactions. The advantage of this experiment is to perform exclusive measurement by missing mass study using the primary neutrons and invariant mass spectroscopy via such decay as K{sup -}pp{yields}{Lambda}p{yields}p{pi}{sup -}p, simultaneously. In this report, an overview of this experiment and the current status are presented.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

A low-temperature crystallization path for device-quality ferroelectric films

We show a path for low-temperature crystallization of device-quality solution-processed lead zirconate titanate films. The essential aspect of the path is to circumvent pyrochlore formation at around 300 deg. C during temperature increase up to 400 deg. C. By maintaining enough carbon via pyrolysis at 210 deg. C, well below the temperature for pyrochlore formation, Pb{sup 2+} can be reduced to Pb{sup 0}. This leads to the lack of Pb{sup 2+} in the film to suppress the development of pyrochlore, which accounts for the usual high-temperature conversion to perovskite. Films on metal, metal/oxide hybrid, and oxide bottom electrodes were successfully crystallized at 400-450 deg. C.

36 MATERIALS SCIENCE↗
DOE OSTI2010

Carbon-doped single-crystalline SiGe/Si thermistor with high temperature coefficient of resistance and low noise level

SiGe (C)/Si(C) multiquantum wells have been studied as a thermistor material for future bolometers. A thermistor material for uncooled Si-based thermal detectors with thermal coefficient of resistance of 4.5%/K for 100x100 {mu}m{sup 2} pixel sizes and low noise constant (K{sub 1/f}) value of 4.4x10{sup -15} is presented. The outstanding performance of the devices is due to Ni-silicide contacts, smooth interfaces, and high quality multiquantum wells containing high Ge content.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

Photoelectron spectroscopic studies of 5-halouracil anions

The parent negative ions of 5-chlorouracil, UCl{sup -} and 5-fluorouracil, UF{sup -} have been studied using anion photoelectron spectroscopy in order to investigate the electrophilic properties of their corresponding neutral halouracils. The vertical detachment energies (VDE) of these anions and the adiabatic electron affinities (EA) of their neutral molecular counterparts are reported. These results are in good agreement with the results of previously published theoretical calculations. The VDE values for both UCl{sup -} and UF{sup -} and the EA values for their neutral molecular counterparts are much greater than the corresponding values for both anionic and neutral forms of canonical uracil and thymine. These results are consistent with the observation that DNA is more sensitive to radiation damage when thymine is replaced by halouracil. While we also attempted to prepare the parent anion of 5-bromouracil, UBr{sup -}, we did not observe it, the mass spectrum exhibiting only Br{sup -} fragments, i.e., 5-bromouracil apparently underwent dissociative electron attachment. This observation is consistent with a previous assessment, suggesting that 5-bromouracil is the best radio-sensitizer among these three halo-nucleobases.

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

Light hadronic decays and decay rates of quarkonia

The Light hadronic decay and decay rates of mesons (QQ-bar) are studied in the NRQCD formalism in terms of their short distance and long distance coefficients. The long distance coefficients are obtained through phenomenological potential model description of the mesons. The mass spectrum of the and mesons are reviewed in non-relativistic phenomenological quark antiquark potential of the type V(r) = -({alpha}{sub c}/r)+Ar{sup {nu}}, with {nu} varying from 0.5 to 2. The digamma and quarkonia decays into light hadrons are investigated by incorporating the relativistic corrections of order v{sup 4} within the NRQCD formalism.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Roper Resonance in 2+1 Flavor QCD

The low-lying even-parity states of the nucleon are explored in lattice QCD using the PACS-CS collaboration 2+1-flavor dynamical-QCD gauge-field configurations. The established correlation-matrix approach is used, in which various fermion source and sink smearings are utilized to provide an effective basis of interpolating fields to span the space of low-lying energy eigenstates. Of particular interest is the nature of the first excited state of the nucleon, the N(1/2){sup +} Roper resonance of P{sub 11} pion-nucleon scattering. The Roper state of the present analysis approaches the physical mass, displaying significant chiral curvature at the lightest quark mass. These full QCD results, providing the world's first insight into the nucleon mass spectrum in the light-quark regime, are significantly different from those of quenched QCD and provide interesting insights into the dynamics of QCD.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Dynamics Behind the Quark Mass Hierarchy and Electroweak Symmetry breaking

I review the dynamics in a new class of models describing the quark mass hierarchy, suggested recently by Michio Hashimoto and the author. In this class, the dynamics primarily responsible for electroweak symmetry breaking (EWSB) leads to the mass spectrum of quarks with no (or weak) isospin violation. Moreover, the values of these masses are of the order of the observed masses of the down-type quarks. Then, strong (although subcritical) horizontal diagonal interactions for the t quark plus horizontal flavor-changing neutral interactions between different families lead (with no fine tuning) to a realistic quark mass spectrum. In this scenario, many composite Higgs bosons occur. A concrete model with the dynamical EWSB with the fourth family is described in detail.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Pyramidal inversion domain boundaries revisited

The structure of pyramidal inversion domain boundaries in GaN:Mg was investigated by aberration corrected transmission electron microscopy. The analysis shows the upper (0001) boundary to consist of a single Mg layer inserted between polarity inverted GaN layers in an abcab stacking. The Mg bound in these defects is at least one order of magnitude lower than the chemical Mg concentration. Temperature dependent Hall effect measurements show that up to 27% of the Mg acceptors is electrically compensated.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2011

2540 km: Bimagic baseline for neutrino oscillation parameters

We consider a low energy neutrino factory setup with a detector placed at a distance of 2540 km. At this baseline, for both normal and inverted hierarchical neutrino mass spectrum, the wrong-sign muon event spectrum is almost independent of CP phase {delta} and the mixing angle {theta}{sub 13} in a specific energy window. This leads to an unambiguous determination of the hierarchy. In addition, a part of the muon spectrum remain sensitive to {delta} and {theta}{sub 13}, so that the same setup can be used to probe these parameters as well using a broadband beam.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗