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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 1,387 records · Page 77
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

A Ruler To Measure The Universe : Probing Dark Energy with Baryon Acoustic Oscillations

Understanding the nature of the dark energy that is responsible for roughly 70% of the energy content of the Universe and is causing the accelerated expansion of the Universe is one of the foremost problems in cosmology today. This grant supported the development of the Baryon Acoustic Oscillation (BAO) technique to measure the expansion rate of the Universe and thereby constrain the properties of the dark energy. The primary achievement over the course of the grant was the development of the reconstruction technique for BAO which enhances the constraining power of this method. At the start of this grant, this reconstruction technique, although theoretically studied, had not been applied to data. The work supported by this grant helped make reconstruction a standard technique in the analysis of BAO data. This grant also supported analyses using the Baryon Oscillation Spectroscopic Survey (BOSS, supported by DOE), as well as theoretical work in preparation for the next generations of surveys, most notably the Dark Energy Spectroscopic Instrument (DESI).

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Data Archive and Portal (DAP) Platform for Solid Phase Processing Technologies

The scale and speed of data generated by modern scientific experiments have constantly challenged the research community to store, curate, manage and optimally use it to drive scientific discoveries. In this work, we have developed a data archive and portal (DAP) platform including analytics capabilities to collect, curate, and manage data and metadata stream for solid phase processing (SPP) techniques. We successfully hosted around ~347K files of data related to processing parameters, microscopic images, and spectroscopic data related to solid phase processing. The DAP platform for SPP will establish an enduring capability to support machine learning and grow collaboration at the intersection of materials science and data science.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Characterization of Gramicidin A in Triblock and Diblock Polymersomes and Hybrid Vesicles via Continuous Wave Electron Paramagnetic Resonance Spectroscopy

Studying membrane proteins in a native environment is crucial to understanding their structural and/or functional studies. Often, widely accepted mimetic systems have limitations that prevent the study of some membrane proteins. Micelles, bicelles, and liposomes are common biomimetic systems but have problems with membrane compatibility, limited lipid composition, and heterogeneity. To overcome these limitations, polymersomes and hybrid vesicles have become popular alternatives. Polymersomes form from amphiphilic triblock or diblock copolymers and are considered more robust than liposomes. Hybrid vesicles are a combination of lipids and block copolymers that form vesicles composed of a mixture of the two. These hybrid vesicles are appealing because they have the native lipid environment of bilayers but also the stability and customizability of polymersomes. Gramicidin A was incorporated into these polymersomes and characterized using continuous wave electron paramagnetic resonance (CW-EPR) and transmission electron microscopy (TEM). EPR spectroscopy is a powerful biophysical technique used to study the structure and dynamic properties of membrane proteins in their native environment. Spectroscopic studies of gramicidin A have been limited to liposomes; in this study, the membrane peptide is studied in both polymersomes and hybrid vesicles using CW-EPR spectroscopy. Lineshape analysis of spin-labeled gramicidin A revealed linewidth broadening, suggesting that the thicker polymersome membranes restrict the motion of the spin label more when compared to liposome membranes. Statement of Significance: Understanding membrane proteins’ structures and functions is critical in the study of many diseases. In order to study them in a native environment, membrane mimetics must be developed that can be suitable for obtaining superior biophysical data quality to characterize structural dynamics while maintaining their native functions and structures. Many currently widely accepted methods have limitations, such as a loss of native structure and function, heterogeneous vesicle formation, restricted lipid types for the vesicle formation for many proteins, and experimental artifacts, which leaves rooms for the development of new biomembrane mimetics. The triblock and diblock polymersomes and hybrid versicles utilized in this study may overcome these limitations and provide the stability and customizability of polymersomes, keeping the biocompatibility and functionality of liposomes for EPR studies of membrane proteins.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2017

The Discovery of λ Bootis Stars: The Southern Survey I

The λ Boo stars are a class of chemically peculiar Population I A-type stars characterized by under-abundances of the refractory elements, but near-solar abundances of carbon, nitrogen, oxygen, and sulfur. There is some evidence that λ Boo stars have higher frequencies of “bright” debris disks than normal A-type stars. The discovery of four exoplanets orbiting HR 8799, a λ Boo star with a resolved debris disk, suggests that the λ Boo phenomenon may be related to the presence of a dynamic debris disk, perhaps perturbed by migrating planets. However, only 64 λ Boo stars are known, and those stars were discovered with different techniques, making it problematic to use that sample for statistical purposes, including determining the frequency of debris disks. The purpose of this paper is to derive a new sample of λ Boo stars using a technique that does not lead to biases with respect to the presence of infrared excesses. Through spectroscopic observations in the southern hemisphere, we have discovered 33 λ Boo stars and have confirmed 12 others. As a step toward determining the proportion of λ Boo stars with infrared excesses, we have used WISE data to examine the infrared properties of this sample out to 22 μ m. On this basis, we cannot conclude that λ Boo stars have a greater tendency than normal A-type stars to show infrared excesses. However, observing this sample at longer wavelengths may change that conclusion, as many λ Boo debris disks are cool and do not radiate strongly at 22 μ m.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1990

Ellipsometric study of YBa2Cu3O(7-x) laser ablated and co-evaporated films

High temperature superconducting films of YBa2Cu3O(7-x) (YBCO were grown on SrTiO3, LaA1O3, and YSZ substrates using two techniques: excimer laser ablation with in situ annealing and co-evaporation of Y, Cu, and BaF2 with ex-situ annealing. Film thicknesses were typically 5000 A, with predominant c-axis alignment perpendicular to the substrate. Critical temperatures up to Tc(R=O)=90 K were achieved by both techniques. Ellipsometric measurements were taken in the range 1.6 to 4.3 eV using a variable angle spectroscopic ellipsometer. The complex dielectric function of the laser ablated films was reproducible from run to run, and was found to be within 10 percent of that previously reported for (001) oriented single crystals. A dielectric overlayer was observed in these films, with an index of refraction of approximately 1.55 and nearly zero absorption. For the laser ablated films the optical properties were essentially independent of substrate material. The magnitude of the dielectric function obtained for the co-evaported films was much lower than the value reported for single crystals, and was sample dependent.

Alterovitz, S. A.↗
NASA NTRS1990

Diagnostic evaluations of microwave generated helium and nitrogen plasma mixtures

The goal of this work is to continue the development to fundamentally understand the plasma processes as applied to spacecraft propulsion. The diagnostic experiments used are calorimetric, dimensional, and spectroscopic measurements using the TM 011 and TM 012 modes in the resonance cavity. These experimental techniques are highly important in furthering the understanding of plasma phenomena and of designing rocket thrusters. Several experimental results are included using nitrogen and helium gas mixtures.

Haraburda, Scott S.↗
NASA NTRS1990

Ellipsometric study of YBa2Cu3O(7-x) laser ablated and co-evaporated films

High temperature superconducting films of YBa2Cu3O(7-x) (YBCO) were grown on SrTiO3, LaAl03, and YSZ substrates using two techniques: excimer laser ablation with in situ annealing and co-evaporation of Y, Cu, and BaF2 with ex-situ annealing. Film thicknesses were typically 5000 A, with predominant c-axis alignment perpendicular to the substrate. Critical temperatures up to Tc(R = 0) = 90 K were achieved by both techniques. Ellipsometric measurements were taken in the range 1.6 to 4.3 eV using a variable angle spectroscopic ellipsometer. The complex dielectric function of the laser ablated films was reproducible from run to run, and was found to be within 10 percent of that previously reported for (001) oriented single crystals. A dielectric overlayer was observed in these films, with an index of refraction of approximately 1.55 and nearly zero absorption. For the laser ablated films the optical properties were essentially independent of substrate material. The magnitude of the dielectric function obtained for the co-evaporated films was much lower than the value reported for single crystals, and was sample dependent.

Alterovitz, S. A.↗
NASA NTRS2004

Coronagraphic Methods for the Detection of Terrestrial Planets

I will contribute (i.e. join in writing the TPF-C Report) for the following workshop topics: 1) Science Topics (target list): I describe a new target list for the TPF-C based on General TPF target list maintained at the US Naval Observatory; 2) Science Topics (spectroscopy): I describe the need for optical, imaging, pulse-counting detectors for spectroscopy of terrestrial planets; 3) Simulation and Modeling Techniques: I describe work at Goddard Space Flight Center to simulate wide-band imagery and spectroscopic imagery that will be obtained by TPF-C.

Heap, Sally↗
NASA NTRS1998

Near Infrared Observations of a Redshift 5.34 Galaxy: Further Evidence for Significant Dust Absorption in the Early Universe

In the last several years, the combination of new wavelength dropout discovery techniques coupled with the incredible power of deep imaging of the Hubble Space Telescope and the spectroscopic capabilities of a new generation of large ground-based telescopes, has lead to an astonishing blossoming of the study of galaxies at redshifts of z=2-4, when the Universe was less than 10-20% of its current age.

near infrared redshift 5.34 galaxy high redshift y↗
NASA NTRS2009

Biosensors for EVA: Muscle Oxygen and pH During Walking, Running and Simulated Reduced Gravity

During lunar excursions in the EVA suit, real-time measurement of metabolic rate is required to manage consumables and guide activities to ensure safe return to the base. Metabolic rate, or oxygen consumption (VO2), is normally measured from pulmonary parameters but cannot be determined with standard techniques in the oxygen-rich environment of a spacesuit. Our group developed novel near infrared spectroscopic (NIRS) methods to calculate muscle oxygen saturation (SmO2), hematocrit, and pH, and we recently demonstrated that we can use our NIRS sensor to measure VO2 on the leg during cycling. Our NSBRI-funded project is looking to extend this methodology to examine activities which more appropriately represent EVA activities, such as walking and running and to better understand factors that determine the metabolic cost of exercise in both normal and lunar gravity. Our 4 year project specifically addresses risk: ExMC 4.18: Lack of adequate biomedical monitoring capability for Constellation EVA Suits and EPSP risk: Risk of compromised EVA performance and crew health due to inadequate EVA suit systems.

Lee, S. M. C.↗
NASA NTRS2023

Cavity Ring-Down Spectroscopy of Anthracene, 9-Methylanthracene, and 2 Methylanthracene in Supersonic Expansion

The S0–S1 absorption spectra of anthracene (C14H10), 9-methylanthracene (C15H12), and 2-methylanthracene (C15H12) are measured in the ultraviolet region between 330 and 375 nm (26,666 to 30,303 cm–1) with cavity ring-down spectroscopy in supersonic free-jet expansions of argon. The associated vibronic band systems and their spectroscopic assignments are discussed and compared to previous studies performed using fluorescence excitation and dispersed fluorescence techniques. Density functional theory (DFT) calculations were carried out to study the structures and evaluate the vibrational transitions of the ground and excited states. Time-dependent DFT calculations of the first electronic excited states and Franck–Condon factor calculations were carried out to assist in the assignment of the experimentally measured vibronic bands. The vibronic spectra obtained in absorption agree well with fluorescence excitation spectra in terms of peak positions but exhibit different relative band intensities. We find a very good match between experimentally obtained vibronic line positions and the peak positions of the quantum chemically calculated Franck–Condon excitation lines.

Salma Bejaoui↗
NASA NTRS1990

Photoelectrochemical fabrication of spectroscopic diffraction gratings, phase 2

This program was directed toward the production of Echelle diffraction gratings by a light-driven, electrochemical etching technique (photoelectrochemical etching). Etching is carried out in single crystal materials, and the differential rate of etching of the different crystallographic planes used to define the groove profiles. Etching of V-groove profiles was first discovered by us during the first phase of this project, which was initially conceived as a general exploration of photoelectrochemical etching techniques for grating fabrication. This highly controllable V-groove etching process was considered to be of high significance for producing low pitch Echelles, and provided the basis for a more extensive Phase 2 investigation.

Rauh, R. David↗
NASA NTRS1998

Ensembles of radial basis function networks for spectroscopic detection of cervical precancer

The mortality related to cervical cancer can be substantially reduced through early detection and treatment. However, current detection techniques, such as Pap smear and colposcopy, fail to achieve a concurrently high sensitivity and specificity. In vivo fluorescence spectroscopy is a technique which quickly, noninvasively and quantitatively probes the biochemical and morphological changes that occur in precancerous tissue. A multivariate statistical algorithm was used to extract clinically useful information from tissue spectra acquired from 361 cervical sites from 95 patients at 337-, 380-, and 460-nm excitation wavelengths. The multivariate statistical analysis was also employed to reduce the number of fluorescence excitation-emission wavelength pairs required to discriminate healthy tissue samples from precancerous tissue samples. The use of connectionist methods such as multilayered perceptrons, radial basis function (RBF) networks, and ensembles of such networks was investigated. RBF ensemble algorithms based on fluorescence spectra potentially provide automated and near real-time implementation of precancer detection in the hands of nonexperts. The results are more reliable, direct, and accurate than those achieved by either human experts or multivariate statistical algorithms.

Cervix Neoplasms/pathology↗
DOE OSTI2013

XEDS STEM Tomography For 3D Chemical Characterization Of Nanoscale Particles

We present a tomography technique which couples scanning transmission electron microscopy (STEM) and X-ray energy dispersive spectrometry (XEDS) to resolve 3D distribution of elements in nanoscale materials. STEM imaging when combined with a symmetrically arranged XEDS detector design around the specimen overcomes many of the obstacles in 3D spectroscopic tomography of nanoscale materials and successfully elucidate the 3D chemical information in a large field of view of the TEM sample. We employed this technique to investigate 3D distribution of Nickel (Ni), Manganese (Mn) and Oxygen (O) in Li(NiMn)O2 battery cathode material. For this purpose, 2D elemental maps were acquired for a range of tilt angles and reconstructed to obtain 3D elemental distribution in an isolated Li(NiMnO2) nanoparticle. The results highlight the strength of this technique in 3D chemical analysis of nanoscale materials by successfully resolving Ni, Mn and O elemental distributions in 3D and discovering the new phenomenon of Ni surface segregation in this material. Furthermore, the comparison of simultaneously acquired HAADF STEM and XEDS STEM tomography results show that XEDS STEM tomography provides additional 3D chemical information of the material especially when there is low atomic number (Z) contrast in the material of interest.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2016

Trisulfonamide Ligands for F-Metal Complexation and Extraction from Alkaline Solutions

Selective actinide (An) complexation and extraction from acidic streams, resulting from fuel processing, has been extensively investigated, whereas caustic-side An extraction from alkaline high-level waste (HLW) streams is much less explored. In Savannah River Site, HLW is treated for Cesium removal by the Caustic-Side Solvent Extraction (CSSX) process, which has been invented in Oak Ridge National Laboratory (ORNL). Sr and An are removed before CSSX via an actinide removal process (ARP), which uses modified monosodium titanate (MMST). Several aspects of CSSX have been improved by the Next- Generation Caustic-Side Solvent Extraction (NG-CSSX) process. In this work, introduction of new organic ligands for combined Cs/An extraction is proposed as a possible modification of NG-CSSX process. Combined Cs and An separation could reduce the amount of MMST needed for the ARP leading to better economics. Trisulfonamides were synthesized as follows: 1,3,5- Tris(bromomethyl)-2,4,6-trialkyl-benzene was reacted with Na{sub 2}SO{sub 3} in boiling H{sub 2}O/alcohol. The 1,3,5-tris(sulfomethyl)- 2,4,6-trialkyl-benzene product was stirred with excess of PCl5 in POCl{sub 3} under N{sub 2}, resulting in 1,3,5- tris(chlorosulfonyl-methyl)-2,4,6-trialkyl-benzene. Reaction with substituted anilines led to formation of tri-sulfonamides. All compounds were characterized by IR and {sup 1}H NMR. The synthesized ligands will be tested for incorporation into an alternative solvent extraction technology for combined extraction of Cs, Sr, and An from alkaline HLW streams. Selectivity of tri-sulfonamides towards selected fission products and actinides in liquid-liquid extraction experiments will be studied by tracer techniques at ORNL. Instrumental methods that will be used for characterization include NMR, UV-Vis, and FT-IR spectroscopic methods, mass spectrometry, and X-ray crystallography. (authors)

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2011

SPECTROSCOPIC ON-LINE MONITORING FOR PROCESS CONTROL AND SAFEGUARDING OF RADIOCHEMICAL STREAMS

There is a renewed interest worldwide to promote the use of nuclear power and close the nuclear fuel cycle. The long term successful use of nuclear power is critically dependent upon adequate and safe processing and disposition of the spent nuclear fuel. Liquid-liquid extraction is a separation technique commonly employed for the processing of the dissolved spent nuclear fuel. The instrumentation used to monitor these processes must be robust, require little or no maintenance, and be able to withstand harsh environments such as high radiation fields and aggressive chemical matrices. In addition, the ability for continuous online monitoring allows for numerous benefits. Our team experimentally assessed the potential of Raman and spectrophotometric techniques for on-line real-time monitoring of the U(VI)/nitrate ion/nitric acid and Pu(IV)/Np(V)/Nd(III), respectively, in solutions relevant to spent fuel reprocessing. Both techniques demonstrated robust performance in the repetitive batch measurements of each analyte in a wide concentration range using simulant and commercial dissolved spent fuel solutions. Static spectroscopic measurements served as training sets for the multivariate data analysis to obtain partial least squares predictive models, which were validated using on-line centrifugal contactor extraction tests. This paper summarizes or methodology and results of the U(VI)/nitrate system as a specific example.

separations, PUREX, U, Pu, Np, nitic acid, TBP dod↗
NASA NTRSDate not supplied

Spectral Characterization of Spacecraft Materials used in Hypervelocity Impact Testing

The increasing number of successfully deployed space missions have resulted in an increased density of man-made objects positioned in orbital domains near Earth. With this steady accumulation of objects in space, it is becoming more imperative to characterize spacecraft materials, which may ultimately be contributors to the orbital debris population. In order to ascertain the potential damage from orbital debris, a laboratory hypervelocity impact test was conducted using a 56-kg modern spacecraft representative satellite (DebriSat) to simulate a catastrophic fragmentation event in low Earth orbit. In an effort to identify unique, material-specific spectroscopic markers, a select number of the spacecraft materials used to construct DebriSat were analyzed using reflectance spectroscopy as a characterization technique for assessment on material type according to optical features. Spectral measurements of DebriSat materials analyzed prior to the laboratory impact are presented in this paper. These data provide a spectral characterization baseline for modern-day spacecraft materials in their pristine conditions and are compared to each other to distinguish spectra of materials belonging to different classifications with an effort of grouping them using color index. The ongoing efforts to classify materials utilizing their reflectance spectroscopic fingerprint are discussed in this study

Jacqueline A. Reyes↗
DOE OSTI2011

Chemical Imaging of Catalyst Deactivation during the Conversion of Renewables at the Single Particle Level: The Etherification of Biomass-based Polyols with Alkenes over H-Beta Zeolites

The etherification of biomass-based alcohols with various linear {alpha}-olefins under solvent-free conditions was followed in a space- and time-resolved manner on 9 {micro}m large H-Beta zeolite crystals by confocal fluorescence microscopy. This allowed us to visualize the interaction with the substrate and distribution of the coke products into the catalyst at the level of an individual zeolite crystal during the etherification process. The spectroscopic information obtained on the micrometer-scale zeolite was in line with the results obtained with bulk characterization techniques and further confirmed by the catalytic results obtained both for micrometer-scale and nanoscale zeolites. This allowed us to explain the influence of the substrate type (glycerol, glycols, and alkenes) and zeolite properties (Si/Al ratio and particle size) on the etherification activity. The etherification of the biomass-based alcohols takes place mainly on the external surface of the zeolite particles. The gradual blockage of the external surface of the zeolite results in a partial or total loss of etherification activity. The deactivation could be attributed to olefin oligomerization. The high conversions obtained in the etherification of 1,2-propylene glycol with long linear alkenes (up to 80%) and the pronounced deactivation of the zeolite observed in the etherification of glycerol with long linear alkenes (max. 20% conversion) were explained by the spectroscopic measurements and is due to differences in the adsorption, i.e., in the center of the zeolite particle for glycerol and on the external surface in the case of glycols.

01 COAL, LIGNITE, AND PEAT↗