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At least 1,279 records · Page 71
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Protein Dynamics by Two-Dimensional Infrared Spectroscopy

Proteins function as ensembles of interconverting structures. The motions span from picosecond bond rotations to millisecond and longer subunit displacements. Characterization of functional dynamics on all spatial and temporal scales remains challenging experimentally. Two-dimensional infrared spectroscopy (2D IR) is maturing as a powerful approach for investigating proteins and their dynamics. We outline the advantages of IR spectroscopy, describe 2D IR and the information it provides, and introduce vibrational groups for protein analysis. We highlight example studies that illustrate the power and versatility of 2D IR for characterizing protein dynamics and conclude with a brief discussion of the outlook for biomolecular 2D IR.

Chemistry↗
DOE OSTI2023

Improving Tropical Cyclogenesis Forecasts of Hurricane Irma (2017) through the Assimilation of All-Sky Infrared Brightness Temperatures

The assimilation of satellite all-sky infrared (IR) brightness temperatures (BTs) has been shown in previous studies to improve intensity forecasts of tropical cyclones. Here, in this study, we examine whether assimilating all-sky IR BTs can also potentially improve tropical cyclogenesis forecasts by improving the pregenesis cloud and moisture fields. By using an ensemble-based data assimilation system, we show that the assimilation of upper-tropospheric water vapor channel BTs observed by the Meteosat-10 SEVIRI instrument two days before the formation of a tropical depression improves the genesis forecast of Hurricane Irma (2017), a classic Cape Verde storm, by up to 24 h while also capturing its later rapid intensification in deterministic forecasts. In an experiment that withholds the assimilation of all-sky IR BTs, the assimilation of conventional observations from the Global Telecommunications System (GTS) leads to the premature genesis of Hurricane Irma by at least 24 h. This premature genesis is shown to result from an overestimation of the spatial coverage of deep convection within the African easterly wave (AEW) from which Irma eventually forms. The gross overestimation of deep convection without all-sky IR BTs is accompanied by higher column saturation fraction, stronger low-level convergence, and the earlier spinup of a low-level meso- β -scale vortex within the AEW that ultimately becomes Hurricane Irma. Through its adjustment to the initial moisture and cloud conditions, the assimilation of all-sky IR BTs leads to a more realistic convective evolution in forecasts and ultimately a more realistic timing of genesis.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Saccharomyces cerevisiae CellWall Remodeling in the Absence of Knr4 and Kre6 Revealed by Nano-FourierTransform Infrared Spectroscopy

The cell wall integrity (CWI) signaling pathway regulates yeast cell wall biosynthesis, cell division, and responses to external stress. The cell wall, comprised of a dense network of chitin, β-1,3- and β-1,6- glucans, and mannoproteins, is very thin, <100 nm. Alterations in cell wall composition may activate the CWI pathway. Saccharomyces cerevisiae, a model yeast, was used to study the role of individual wall components in altering the structure and biophysical properties of the yeast cell wall. Near-field Fourier transform infrared spectroscopy (nano-FT-IR) was used for the first direct, spectrochemical identification of cell wall composition in a background (wild-type) strain and two deletion mutants from the yeast knock-out collection: kre6Δ and knr4Δ. Killer toxin resistant 6 (Kre6) is an integral membrane protein required for biosynthesis of β-1,6-glucan, while Knr4 is a cell signaling protein involved in the control of cell wall biosynthesis, in particular, biosynthesis and deposition of chitin. Complementary spectral data were obtained with far-field (FF)-FT-IR, in transmission, and with attenuated total reflectance (ATR) spectromicroscopy with 3 –10 μm wavelength-dependent spatial resolution. The FF-FT-IR spectra of cells and spectra of isolated cell wall components showed that components of the cell body dominated transmission spectra and were still evident in ATR spectra. In contrast, the nano-FT-IR at ~25 nm spatial resolution could be used to characterize the yeast wall chemical structure. Our results show that the β-1,6-glucan content is decreased in kre6Δ, while all glucan content is decreased in the knr4Δ cell wall. The latter may be thinner than in wild type, since not only are mannan and chitin detectable by nano-FT-IR, but also lipid membranes and protein, indicative of cell interior.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

In-Rod Sensor System Overview, Benefits and Recent Irradiation Test Results

Westinghouse is developing an In-Rod Sensor (IRS) System capable of measuring critical fuel rod parameters such as center-line fuel temperature, rod internal pressure and axial fuel pellet stack elongation without having penetrations to the fuel rod. The technology is similar to the Halden Reactor instrumentation, but the IRS system focuses on commercial fuel rod instrumentation. Both systems circumvent fuel rod penetrations, however the IRS system overcomes unique geometric challenges found in commercial fuel rod assemblies. The IRS could also play a key role in accelerated fuel qualification by allowing real-time measurements during separate effects tests, integral fuel testing or during irradiation of lead test rods or lead test assemblies. Combining these measurements with data acquired from targeted separate effects testing and multi-scale modelling could significantly reduce the time required to qualify new fuel and reduce the safety margin uncertainty of operating plants. The IRS is actively in development for Light Water Reactors (LWR) based fuel assemblies but can also be applied to Gen IV reactor designs with minimal modifications.

Carvajal, Jorge↗
DOE OSTI2022

Non-Destructive In-Process Assessment of Thermal Spray Repairs

This exploratory project, entitled “Non-Destructive In-process Assessment of Thermal Spray Repairs,” evaluated the capabilities and limitations of four non-destructive testing (NDE) technologies for detection of defects in as-sprayed thermal spray coatings: acousto-ultrasonics, vibro-thermography, thermal wave infrared (IR) imaging, and flash IR thermography. The project goal was to identify a single technology suitable for use as an in-process inspection for two common classes of defects in thermal spray coatings, porosity and disbonds. Two rounds of test coupons were fabricated with intentionally seeded defects in AISI 420 stainless steel coatings deposited by twin wire arc (TWA) spray onto gray cast iron substrates. These standardized test coupons allowed the sensitivity of the four NDE methods to be directly compared. The results indicated that the acousto-ultrasonic method will not meet requirements for accuracy, inspection time, and reproducibility, while the vibrothermography method will not meet requirements for integration within remanufacturing cells and process flows. The IR methods, thermal wave imaging and flash thermography, both exhibited acceptable accuracy and reproducibility; however, the former method does not meet the requirement for inspection time. Flash IR thermography met all requirements in the initial round of testing, and that result was confirmed in a second round of testing on samples with a larger, more complex geometry. A final recommendation for further development of flash IR thermography was therefore made based upon i) detection performance, and ii) feasibility of deployment into the target application of resurfacing CAT engine blocks and headers.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Mid-infrared Pulsed Upconversion Imaging in a Rotating Detonation Combustor

To meet the challenges associated with performing mid-InfraRed (IR) imaging in Rotating Detonation Combustors (RDCs), a novel pulsed mid-IR UpConversion Imaging (UCI) diagnostic has been implemented. UCI is an alternative to direct mid-IR detection that uses nonlinear optical frequency mixing to shift mid-IR wavelengths carrying a target image to shorter wavelengths that can be imaged with high-performance silicon-based CCD/CMOS cameras. This approach offers several favorable properties including high spectral selectivity, high temporal resolution, and superior low-light detectivity. A hydrogen-air research RDC was operated with carbon dioxide addition to allow pulsed UCI imaging of mid-IR luminosity within the combustion channel from spontaneous thermal emissions. The resulting measurements demonstrate high spatiotemporal resolution capable of imaging small structures near the supersonically propagating detonation wave front. The results show how this technique can be used to observe sharp gradients and millimeter-scale structures in the high-temperature, high-pressure zones RDC flow fields.

White, Logan W.↗
DOE OSTI2023

The Galaxy–Halo Connection of DESI Luminous Red Galaxies with Subhalo Abundance Matching

Abstract We use subhalo abundance and age distribution matching to create magnitude-limited mock galaxy catalogs at z ∼ 0.43, 0.52, and 0.63 with z -band and 3.4 μ m W 1-band absolute magnitudes and r − z and r − W 1 colors. From these magnitude-limited mocks, we select mock luminous red galaxy (LRG) samples according to the ( r − z )-based (optical) and ( r − W 1)-based (infrared) selection criteria for the LRG sample of the Dark Energy Spectroscopic Instrument (DESI) survey. Our models reproduce the number densities, luminosity functions, color distributions, and projected clustering of the DESI Legacy Surveys that are the basis for DESI LRG target selection. We predict the halo occupation statistics of both optical and IR DESI LRGs at fixed cosmology and assess the differences between the two LRG samples. We find that IR-based SHAM modeling represents the differences between the optical and IR LRG populations better than using the z band and that age distribution matching overpredicts the clustering of LRGs, implying that galaxy color is uncorrelated with halo age in the LRG regime. Both the optical and IR DESI LRG target selections exclude some of the most luminous galaxies that would appear to be LRGs based on their position on the red sequence in optical color–magnitude space. Both selections also yield populations with a nontrivial LRG–halo connection that does not reach unity for the most massive halos. We find that the IR selection achieves greater completeness (≳90%) than the optical selection across all redshift bins studied.

Berti, Angela M. (ORCID:0000000335826649)↗
DOE OSTI2024

Composite materials with adjustable spectral properties

Composite materials with adjustable spectral properties comprised of IR-reflecting micro-domains overlaying an IR-transparent elastomeric matrix, and capable of dynamically controlling IR radiation transmission are described, as well as methods of fabrication thereof. Systems with capabilities to regulate IR radiation (including heat) transmission based thereon, and methods of regulating IR radiation transmission (including thermal regulation) using the same are also provided.

Source record↗
DOE OSTI2025

Analysis of fast-ion losses measured in MAST-U via infrared thermography and a Fast Ion Loss Detector

Fast-ion losses need to be monitored to avoid damage to plasma facing components. In existing experimental devices, the scintillator-based fast-ion loss detector (FILD) is the most advanced diagnostic for measuring fast-ion losses. However, FILDs provide only local information about the losses. Infrared (IR) thermography can be used as a complementary tool for more global monitoring of the deposition of fast-ion losses on the wall, at the expense of no velocity-space resolution. IR cameras measure the temperature of the plasma facing components. This measurement, determined by a combined effect of the thermal plasma, radiation, neutrons and fast-ion losses, can be decomposed to infer the fast-ion load on the tokamak wall. In this manuscript, a workflow to estimate fast-ion losses via IR thermography is applied to the MAST-U spherical tokamak, using a 1D approximation to extract the experimental heat flux on the FILD front face from IR data. To numerically estimate the different contributions to this total heat flux, the field-line tracing environment SMITER is used to calculate the thermal plasma contribution, the orbit-following Monte-Carlo code ASCOT to estimate the fast-ion losses, and bolometry measurements for the radiation. To validate the workflow, two discharges, L-mode plasmas with low MHD activity, were executed using on and off-axis beams, respectively. The experimentally and numerically estimated heat flux are of the same order of magnitude for the on-axis heated scenario, with a strong dependence of the estimated fast-ion losses contribution on the fit to the kinetic profiles used as input. This is also true for the off-axis heated scenario, where the total numerically estimated heat flux is 2.1 or 1.3 times higher than the maximum experimentally estimated heat flux, depending on the ASCOT input used.

FILD↗
DOE OSTI2024

Iridium Surface Oxide Affects the Nafion Interface in Proton-Exchange-Membrane Water Electrolysis

Proton-exchange-membrane water electrolyzer (PEMWE) catalyst layers consist of aggregates of catalyst particles (typically iridium) and ionomer (typically Nafion). Prior work suggests that the oxide form of Ir affects the kinetics of the oxygen-evolution reaction. However, because most catalyst-benchmarking studies are conducted ex situ in liquid electrolytes, it remains unclear how the ionomer is influenced by the catalyst oxide and affects overall cell performance. Using a suite of experimental techniques, we conduct fundamental investigations into model ink (catalyst and ionomer dispersed in solution) and thin-film systems to inform cell-level overpotential analysis as a function of three forms of Ir (metallic Ir m , oxyhydroxide IrOOH, and oxide IrO 2 ). Furthermore, nafion on Ir m has a high degree of phase separation and higher swelling, likely improving the ionic conductivity. Additionally, Nafion binds most strongly to IrOOH, likely yielding reduced kinetic overpotentials. These findings highlight the intricacies of the ionomer/Ir interface and provide insight into all catalyst-layer systems.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Materials Data on MgSi7Ir3 by Materials Project

MgIr3Si7 crystallizes in the trigonal R-3c space group. The structure is three-dimensional. Mg2+ is bonded to twelve equivalent Si+1.71- atoms to form edge-sharing MgSi12 cuboctahedra. There are six shorter (3.13 Å) and six longer (3.17 Å) Mg–Si bond lengths. Ir+3.33+ is bonded in a 7-coordinate geometry to seven Si+1.71- atoms. There are a spread of Ir–Si bond distances ranging from 2.44–2.52 Å. There are two inequivalent Si+1.71- sites. In the first Si+1.71- site, Si+1.71- is bonded in a distorted trigonal planar geometry to three equivalent Ir+3.33+ atoms. In the second Si+1.71- site, Si+1.71- is bonded in a 3-coordinate geometry to two equivalent Mg2+ and three equivalent Ir+3.33+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on HfB4Ir3 by Materials Project

HfIr3B4 crystallizes in the hexagonal P6_3/m space group. The structure is three-dimensional. Hf is bonded in a 9-coordinate geometry to nine equivalent B atoms. There are three shorter (2.60 Å) and six longer (2.63 Å) Hf–B bond lengths. Ir is bonded in a 6-coordinate geometry to six B atoms. There are a spread of Ir–B bond distances ranging from 2.16–2.46 Å. There are two inequivalent B sites. In the first B site, B is bonded in a body-centered cubic geometry to six equivalent Ir and two equivalent B atoms. Both B–B bond lengths are 1.76 Å. In the second B site, B is bonded in a 9-coordinate geometry to three equivalent Hf, four equivalent Ir, and two equivalent B atoms. Both B–B bond lengths are 2.22 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on B2Mo2Ir by Materials Project

Mo2IrB2 crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. there are two inequivalent Mo sites. In the first Mo site, Mo is bonded in a 7-coordinate geometry to seven B atoms. There are a spread of Mo–B bond distances ranging from 2.34–2.54 Å. In the second Mo site, Mo is bonded in a 4-coordinate geometry to five B atoms. There are a spread of Mo–B bond distances ranging from 2.33–2.65 Å. Ir is bonded in a 3-coordinate geometry to three B atoms. There are two shorter (2.17 Å) and one longer (2.42 Å) Ir–B bond lengths. There are two inequivalent B sites. In the first B site, B is bonded in a 9-coordinate geometry to six Mo, two equivalent Ir, and one B atom. The B–B bond length is 1.86 Å. In the second B site, B is bonded in a 9-coordinate geometry to six Mo, one Ir, and two B atoms. The B–B bond length is 1.88 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ba3NaIr2O9 by Materials Project

Ba3NaIr2O9 is (Cubic) Perovskite-derived structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Na is bonded to six equivalent O atoms to form NaO6 octahedra that share corners with six equivalent IrO6 octahedra and faces with eight BaO12 cuboctahedra. The corner-sharing octahedral tilt angles are 1°. All Na–O bond lengths are 2.27 Å. There are two inequivalent Ba sites. In the first Ba site, Ba is bonded to twelve O atoms to form BaO12 cuboctahedra that share corners with nine BaO12 cuboctahedra, corners with three equivalent IrO6 octahedra, faces with seven BaO12 cuboctahedra, faces with three equivalent NaO6 octahedra, and faces with four equivalent IrO6 octahedra. The corner-sharing octahedral tilt angles are 15°. There are a spread of Ba–O bond distances ranging from 2.98–3.04 Å. In the second Ba site, Ba is bonded to twelve O atoms to form BaO12 cuboctahedra that share corners with twelve BaO12 cuboctahedra, faces with six equivalent BaO12 cuboctahedra, faces with two equivalent NaO6 octahedra, and faces with six equivalent IrO6 octahedra. There are six shorter (2.98 Å) and six longer (2.99 Å) Ba–O bond lengths. Ir is bonded to six O atoms to form IrO6 octahedra that share corners with three equivalent BaO12 cuboctahedra, corners with three equivalent NaO6 octahedra, faces with seven BaO12 cuboctahedra, and a faceface with one IrO6 octahedra. The corner-sharing octahedral tilt angles are 1°. There is three shorter (1.91 Å) and three longer (2.06 Å) Ir–O bond length. There are two inequivalent O sites. In the first O site, O is bonded in a distorted linear geometry to one Na, four Ba, and one Ir atom. In the second O site, O is bonded to four Ba and two equivalent Ir atoms to form a mixture of distorted corner and face-sharing OBa4Ir2 octahedra. The corner-sharing octahedra tilt angles range from 4–60°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sn7Ir3 by Materials Project

Ir3Sn7 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Ir is bonded in a 8-coordinate geometry to eight Sn atoms. There are four shorter (2.79 Å) and four longer (2.81 Å) Ir–Sn bond lengths. There are two inequivalent Sn sites. In the first Sn site, Sn is bonded in a 4-coordinate geometry to three equivalent Ir and four equivalent Sn atoms. There are one shorter (2.81 Å) and three longer (3.14 Å) Sn–Sn bond lengths. In the second Sn site, Sn is bonded in a 8-coordinate geometry to four equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on In2Ir by Materials Project

IrIn2 is Khatyrkite-like structured and crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. Ir is bonded in a 10-coordinate geometry to eight In atoms. There are a spread of Ir–In bond distances ranging from 2.73–2.90 Å. There are two inequivalent In sites. In the first In site, In is bonded in a 4-coordinate geometry to four equivalent Ir atoms. In the second In site, In is bonded in a 4-coordinate geometry to four equivalent Ir atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Al3Ir by Materials Project

IrAl3 is Sodium arsenide structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ir is bonded in a 5-coordinate geometry to eleven Al atoms. There are a spread of Ir–Al bond distances ranging from 2.48–2.82 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded in a trigonal planar geometry to three equivalent Ir and six equivalent Al atoms. All Al–Al bond lengths are 2.82 Å. In the second Al site, Al is bonded in a 1-coordinate geometry to four equivalent Ir and seven Al atoms. There are one shorter (2.66 Å) and three longer (2.77 Å) Al–Al bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ge7Ir3 by Materials Project

Ir3Ge7 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Ir is bonded in a 8-coordinate geometry to eight Ge atoms. There are four shorter (2.58 Å) and four longer (2.61 Å) Ir–Ge bond lengths. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to four equivalent Ir atoms. In the second Ge site, Ge is bonded to three equivalent Ir and one Ge atom to form a mixture of distorted edge and corner-sharing GeGeIr3 tetrahedra. The Ge–Ge bond length is 2.52 Å.

36 MATERIALS SCIENCE↗