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At least 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Pr3Er by Materials Project

ErPr3 is beta Cu3Ti-like structured and crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Er is bonded to twelve Pr atoms to form ErPr12 cuboctahedra that share corners with four equivalent ErPr12 cuboctahedra, corners with eight equivalent PrPr8Er4 cuboctahedra, edges with eight equivalent ErPr12 cuboctahedra, edges with sixteen equivalent PrPr8Er4 cuboctahedra, faces with four equivalent ErPr12 cuboctahedra, and faces with fourteen PrPr8Er4 cuboctahedra. There are four shorter (3.66 Å) and eight longer (3.68 Å) Er–Pr bond lengths. There are two inequivalent Pr sites. In the first Pr site, Pr is bonded to four equivalent Er and eight Pr atoms to form PrPr8Er4 cuboctahedra that share corners with twelve equivalent PrPr8Er4 cuboctahedra, edges with eight equivalent ErPr12 cuboctahedra, edges with sixteen PrPr8Er4 cuboctahedra, faces with four equivalent ErPr12 cuboctahedra, and faces with fourteen PrPr8Er4 cuboctahedra. There are four shorter (3.66 Å) and four longer (3.68 Å) Pr–Pr bond lengths. In the second Pr site, Pr is bonded to four equivalent Er and eight equivalent Pr atoms to form PrPr8Er4 cuboctahedra that share corners with four equivalent PrPr8Er4 cuboctahedra, corners with eight equivalent ErPr12 cuboctahedra, edges with twenty-four PrPr8Er4 cuboctahedra, faces with six equivalent ErPr12 cuboctahedra, and faces with twelve PrPr8Er4 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er4Ga12Ni by Materials Project

Er4NiGa12 crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Er is bonded to twelve Ga atoms to form ErGa12 cuboctahedra that share corners with twelve equivalent ErGa12 cuboctahedra, edges with twelve equivalent GaEr4Ga8 cuboctahedra, faces with six equivalent ErGa12 cuboctahedra, faces with six equivalent GaEr4Ga8 cuboctahedra, and faces with two equivalent NiGa6 octahedra. There are six shorter (3.03 Å) and six longer (3.05 Å) Er–Ga bond lengths. Ni is bonded to six equivalent Ga atoms to form NiGa6 octahedra that share corners with twenty-four equivalent GaEr4Ga8 cuboctahedra and faces with eight equivalent ErGa12 cuboctahedra. All Ni–Ga bond lengths are 2.47 Å. There are two inequivalent Ga sites. In the first Ga site, Ga is bonded to four equivalent Er and eight Ga atoms to form distorted GaEr4Ga8 cuboctahedra that share corners with four equivalent GaEr4Ga8 cuboctahedra, corners with four equivalent NiGa6 octahedra, edges with eight equivalent ErGa12 cuboctahedra, edges with eight equivalent GaEr4Ga8 cuboctahedra, faces with four equivalent ErGa12 cuboctahedra, and faces with six equivalent GaEr4Ga8 cuboctahedra. The corner-sharing octahedral tilt angles are 50°. There are four shorter (2.81 Å) and four longer (3.03 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 5-coordinate geometry to four equivalent Er, one Ni, and four equivalent Ga atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on ErSI by Materials Project

ErSI crystallizes in the hexagonal P-6 space group. The structure is three-dimensional. there are two inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded in a distorted trigonal planar geometry to three S2- and six I1- atoms. There are two shorter (2.59 Å) and one longer (2.60 Å) Er–S bond lengths. There are a spread of Er–I bond distances ranging from 3.61–3.65 Å. In the second Er3+ site, Er3+ is bonded in a trigonal planar geometry to three equivalent S2- and six equivalent I1- atoms. All Er–S bond lengths are 2.59 Å. All Er–I bond lengths are 3.66 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a trigonal planar geometry to three Er3+ and six I1- atoms. There are two shorter (3.64 Å) and four longer (3.65 Å) S–I bond lengths. In the second S2- site, S2- is bonded in a trigonal planar geometry to three equivalent Er3+ and six equivalent I1- atoms. All S–I bond lengths are 3.62 Å. There are two inequivalent I1- sites. In the first I1- site, I1- is bonded to six Er3+ and six S2- atoms to form a mixture of distorted face and edge-sharing IEr6S6 cuboctahedra. In the second I1- site, I1- is bonded to six equivalent Er3+ and six equivalent S2- atoms to form a mixture of distorted face and edge-sharing IEr6S6 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on DyErTe2 by Materials Project

ErDyTe2 is Caswellsilverite-like structured and crystallizes in the tetragonal P4/mmm space group. The structure is three-dimensional. Er is bonded to six Te atoms to form ErTe6 octahedra that share corners with six equivalent ErTe6 octahedra, edges with four equivalent ErTe6 octahedra, and edges with eight equivalent DyTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (3.06 Å) and two longer (3.08 Å) Er–Te bond lengths. Dy is bonded to six Te atoms to form DyTe6 octahedra that share corners with six equivalent DyTe6 octahedra, edges with four equivalent DyTe6 octahedra, and edges with eight equivalent ErTe6 octahedra. The corner-sharing octahedral tilt angles are 0°. There are four shorter (3.06 Å) and two longer (3.08 Å) Dy–Te bond lengths. There are two inequivalent Te sites. In the first Te site, Te is bonded to four equivalent Er and two equivalent Dy atoms to form a mixture of edge and corner-sharing TeDy2Er4 octahedra. The corner-sharing octahedral tilt angles are 0°. In the second Te site, Te is bonded to two equivalent Er and four equivalent Dy atoms to form TeDy4Er2 octahedra that share corners with six equivalent TeDy4Er2 octahedra and edges with twelve TeDy2Er4 octahedra. The corner-sharing octahedral tilt angles are 0°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er3OF10 by Materials Project

(Er3F10)2O2 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of eight water molecules and one Er3F10 framework. In the Er3F10 framework, Er is bonded in a 8-coordinate geometry to eight F atoms. There are four shorter (2.18 Å) and four longer (2.35 Å) Er–F bond lengths. There are two inequivalent F sites. In the first F site, F is bonded in a bent 150 degrees geometry to two equivalent Er atoms. In the second F site, F is bonded in a trigonal non-coplanar geometry to three equivalent Er atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er2Al3Ge4 by Materials Project

Er2Al3Ge4 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. Er is bonded in a 8-coordinate geometry to eight Ge atoms. There are a spread of Er–Ge bond distances ranging from 3.06–3.18 Å. There are two inequivalent Al sites. In the first Al site, Al is bonded to six Ge atoms to form distorted corner-sharing AlGe6 octahedra. The corner-sharing octahedral tilt angles are 30°. There are four shorter (2.56 Å) and two longer (2.75 Å) Al–Ge bond lengths. In the second Al site, Al is bonded in a 5-coordinate geometry to five Ge atoms. There are a spread of Al–Ge bond distances ranging from 2.53–2.85 Å. There are two inequivalent Ge sites. In the first Ge site, Ge is bonded in a 7-coordinate geometry to four equivalent Er and three Al atoms. In the second Ge site, Ge is bonded in a 9-coordinate geometry to four equivalent Er and five Al atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Er4MgS7 by Materials Project

MgEr4S7 crystallizes in the monoclinic Cm space group. The structure is three-dimensional. Mg2+ is bonded to six S2- atoms to form MgS6 octahedra that share corners with three ErS6 octahedra, corners with six ErS7 pentagonal bipyramids, edges with two equivalent MgS6 octahedra, edges with three equivalent ErS6 octahedra, and an edgeedge with one ErS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 2–55°. There are a spread of Mg–S bond distances ranging from 2.59–2.74 Å. There are four inequivalent Er3+ sites. In the first Er3+ site, Er3+ is bonded to seven S2- atoms to form distorted ErS7 pentagonal bipyramids that share corners with four equivalent MgS6 octahedra, corners with four ErS6 octahedra, an edgeedge with one MgS6 octahedra, edges with three equivalent ErS6 octahedra, edges with two equivalent ErS7 pentagonal bipyramids, and faces with two equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 21–72°. There are a spread of Er–S bond distances ranging from 2.69–3.01 Å. In the second Er3+ site, Er3+ is bonded to seven S2- atoms to form distorted ErS7 pentagonal bipyramids that share corners with two equivalent MgS6 octahedra, corners with six ErS6 octahedra, edges with four ErS6 octahedra, edges with two equivalent ErS7 pentagonal bipyramids, and faces with two equivalent ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 22–68°. There are a spread of Er–S bond distances ranging from 2.68–2.95 Å. In the third Er3+ site, Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share a cornercorner with one ErS6 octahedra, corners with two equivalent MgS6 octahedra, corners with six ErS7 pentagonal bipyramids, edges with two equivalent ErS6 octahedra, edges with three equivalent MgS6 octahedra, and an edgeedge with one ErS7 pentagonal bipyramid. The corner-sharing octahedra tilt angles range from 2–54°. There are a spread of Er–S bond distances ranging from 2.65–2.75 Å. In the fourth Er3+ site, Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share a cornercorner with one MgS6 octahedra, a cornercorner with one ErS6 octahedra, corners with four ErS7 pentagonal bipyramids, edges with two equivalent ErS6 octahedra, and edges with six ErS7 pentagonal bipyramids. The corner-sharing octahedra tilt angles range from 54–55°. There are a spread of Er–S bond distances ranging from 2.64–2.71 Å. There are seven inequivalent S2- sites. In the first S2- site, S2- is bonded to one Mg2+ and three Er3+ atoms to form distorted SEr3Mg tetrahedra that share corners with three SEr3Mg tetrahedra, corners with nine SEr5 trigonal bipyramids, and edges with four SEr5 trigonal bipyramids. In the second S2- site, S2- is bonded to four Er3+ atoms to form distorted SEr4 tetrahedra that share corners with three SEr3Mg tetrahedra, corners with nine SEr5 trigonal bipyramids, and edges with four SEr5 trigonal bipyramids. In the third S2- site, S2- is bonded to five Er3+ atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent SEr3Mg tetrahedra, corners with six SEr5 trigonal bipyramids, edges with three SEr3Mg tetrahedra, and edges with six SEr5 trigonal bipyramids. In the fourth S2- site, S2- is bonded to five Er3+ atoms to form distorted SEr5 trigonal bipyramids that share corners with four equivalent SEr4 tetrahedra, corners with six SEr5 trigonal bipyramids, edges with three SEr3Mg tetrahedra, and edges with six SEr5 trigonal bipyramids. In the fifth S2- site, S2- is bonded to one Mg2+ and four Er3+ atoms to form distorted SEr4Mg trigonal bipyramids that share corners with five SEr3Mg tetrahedra, corners with four SEr5 trigonal bipyramids, an edgeedge with one SEr4 tetrahedra, and edges with five SEr5 trigonal bipyramids. In the sixth S2- site, S2- is bonded to two equivalent Mg2+ and three Er3+ atoms to form distorted SEr3Mg2 trigonal bipyramids that share corners with five SEr3Mg tetrahedra, corners with four SEr5 trigonal bipyramids, an edgeedge with one SEr3Mg tetrahedra, and edges with five SEr5 trigonal bipyramids. In the seventh S2- site, S2- is bonded in a rectangular see-saw-like geometry to two equivalent Mg2+ and two equivalent Er3+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Adult weight change and premenopausal breast cancer risk: A prospective pooled analysis of data from 628,463 women

Early-adulthood body size is strongly inversely associated with risk of premenopausal breast cancer. It is unclear whether subsequent changes in weight affect risk. We pooled individual-level data from 17 prospective studies to investigate the association of weight change with premenopausal breast cancer risk, considering strata of initial weight, timing of weight change, other breast cancer risk factors and breast cancer subtype. Hazard ratios (HR) and 95% confidence intervals (CI) were obtained using Cox regression. Among 628,463 women, 10,886 were diagnosed with breast cancer before menopause. Models adjusted for initial weight at ages 18–24 years and other breast cancer risk factors showed that weight gain from ages 18–24 to 35–44 or to 45–54 years was inversely associated with breast cancer overall (e.g., HR per 5 kg to ages 45–54: 0.96, 95% CI: 0.95–0.98) and with oestrogen-receptor(ER)-positive breast cancer (HR per 5 kg to ages 45–54: 0.96, 95% CI: 0.94–0.98). Weight gain from ages 25–34 was inversely associated with ER-positive breast cancer only and weight gain from ages 35–44 was not associated with risk. None of these weight gains were associated with ER-negative breast cancer. Weight loss was not consistently associated with overall or ER-specific risk after adjusting for initial weight. Weight increase from early-adulthood to ages 45–54 years is associated with a reduced premenopausal breast cancer risk independently of early-adulthood weight. Biological explanations are needed to account for these two separate factors.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2023

Coupled primary production and respiration in a large river contrasts with smaller rivers and streams

Abstract Although time series in ecosystem metabolism are well characterized in small and medium rivers, patterns in the world's largest rivers are almost unknown. Large rivers present technical difficulties, including depth measurements, gas exchange (, ) estimates, and the presence of large dams, which can supersaturate gases. We estimated reach‐scale metabolism for the Hanford Reach of the Columbia River (Washington state, USA), a free‐flowing stretch with an average discharge of 3173 . We calculated from semi‐empirical models and directly estimated it from tracer measurements. We fixed at the median value from these calculations (0.5 ), and used maximum likelihood to estimate reach‐scale, open‐channel metabolism. Both gross primary production (GPP) and ecosystem respiration (ER) were high (GPP range: 0.3–30.8 g , ER range: 0.8–30.6 g ), with peak GPP and ER occurring in the late summer or early fall. GPP increased exponentially with temperature, consistent with metabolic theory, while light was seasonally saturating. Annual average GPP, estimated at 1500 g carbon , was in the top 2% of estimates for other rivers. GPP and ER were tightly coupled and 90% of GPP was immediately respired, resulting in net ecosystem production near 0. Patterns in the Hanford Reach contrast with those in small‐medium rivers, suggesting that metabolism magnitudes and patterns in large rivers may not be simply scaled from knowledge of smaller rivers.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2020

High-throughput screening tools facilitate calculation of a combined exposure-bioactivity index for chemicals with endocrine activity

High-throughput and computational tools provide a new opportunity to calculate combined bioactivity of exposure to diverse chemicals acting through a common mechanism. We used high throughput in vitro bioactivity data and exposure predictions from the U.S. EPA’s Toxicity and Exposure Forecaster (ToxCast and ExpoCast) to estimate combined estrogen receptor (ER) agonist activity of non-pharmaceutical chemical exposures for the general U.S. population. High-throughput toxicokinetic (HTTK) data provide conversion factors that relate bioactive concentrations measured in vitro (µM), to predicted population geometric mean exposure rates (mg/kg/day). These data were available for 22 chemicals with ER agonist activity and were estimated for other ER bioactive chemicals based on the geometric mean of HTTK values across chemicals. For each chemical, ER bioactivity across ToxCast assays was compared to predicted population geometric mean exposure at different levels of in vitro potency and model certainty. Dose additivity was assumed in calculating a Combined Exposure-Bioactivity Index (CEBI), the sum of exposure/bioactivity ratios. Combined estrogen bioactivity was also calculated in terms of the percent maximum bioactivity of chemical mixtures in human plasma using a concentration-addition model. Estimated CEBIs vary greatly depending on assumptions used for exposure and bioactivity. In general, CEBI values were <1 when using median of the estimated general population chemical intake rates, while CEBI were ≥1 when using the upper 95th confidence bound for those same intake rates for all chemicals. Concentration-addition model predictions of mixture bioactivity yield comparable results. Based on current in vitro bioactivity data, HTTK methods, and exposure models, combined exposure scenarios sufficient to influence estrogen bioactivity in the general population cannot be ruled out. Future improvements in screening methods and computational models could reduce uncertainty and better inform the potential combined effects of estrogenic chemicals.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2024

Coercive Fields Exceeding 30 T in the Mixed-Valence Single-Molecule Magnet (Cp iPr5 ) 2 Ho 2 I 3

Mixed-valence dilanthanide complexes of the type (Cp iPr5 ) 2 Ln 2 I 3 (Cp iPr5 = pentaisopropylcyclopentadienyl; Ln = Gd, Tb, Dy) featuring a direct Ln–Ln σ-bonding interaction have been shown to exhibit well-isolated high-spin ground states and, in the case of the Tb and Dy variants, a strong axial magnetic anisotropy that gives rise to a large magnetic coercivity. Here, we report the synthesis and characterization of two new mixed-valence dilanthanide compounds in this series, (Cp iPr5 ) 2 Ln 2 I 3 (1-Ln; Ln = Ho, Er). Both compounds feature a Ln–Ln bonding interaction, the first such interaction in any molecular compounds of Ho or Er. Like the Tb and Dy congeners, both complexes exhibit high-spin ground states arising from strong spin–spin coupling between the lanthanide 4f electrons and a single σ-type lanthanide–lanthanide bonding electron. Beyond these similarities, however, the magnetic properties of the two compounds diverge. In particular, 1-Er does not exhibit observable magnetic blocking or slow magnetic relaxation, while 1-Ho exhibits magnetic blocking below 28 K, which is the highest temperature among Ho-based single-molecule magnets, and a spin reversal barrier of 556(4) cm –1 . Additionally, variable-field magnetization data collected for 1-Ho reveal a coercive field of greater than 32 T below 8 K, more than 6-fold higher than observed for the bulk magnets SmCo 5 and Nd 2 Fe 14 B, and the highest coercive field reported to date for any single-molecule magnet or molecule-based magnetic material. Multiconfigurational calculations, supported by far-infrared magnetospectroscopy data, reveal that the stark differences in magnetic properties of 1-Ho and 1-Er arise from differences in the local magnetic anisotropy of the lanthanide centers.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Factors Governing Cloud Growth and Entrainment Rates in Shallow Cumulus and Cumulus Congestus During GoAmazon2014/5

Shallow cumulus and cumulus congestus clouds play an important role in the large-scale tropical circulation by mixing heat and moisture vertically and preconditioning the environment for deeper convection. Different representations of these shallow clouds account for much of the spread in General Circulation Model (GCMs) climate sensitivity, potentially because of how entrainment is represented in GCM parameterizations. This study uses observations from the Department of Energy's Atmospheric Radiation Measurement (ARM) mobile facility deployed at Manacapuru, Brazil, during the Green Ocean Amazon (GoAmazon2014/5) Campaign. Environmental thermodynamic profiles and observations of cloud top height (CTH) are used to constrain an entraining plume model to estimate bulk entrainment rates (ERs). Estimates of CTH are obtained from a combination of vertically pointing W-band ARM cloud radar and 1,290 MHz Radar Wind Profiler observations. A combination of radiosonde, microwave radiometer profiler, and microwave radiometer observations provides new best estimates of the environmental thermodynamic state. We quantify uncertainty in ERs considering uncertainties in estimated CTH, environmental thermodynamic properties, and assumed initial parcel characteristics. We find ERs ranging from 0.16 to 2.8 km -1 with an average of 0.58 ± 0.10 km -1 over a selected population of 469 shallow cumulus and cumulus congestus clouds. Using the retrieved estimates of ER, we evaluate several entrainment closures that are currently used in atmospheric models or have been proposed based on theory or large eddy simulation. Finally, entrainment rates in cumulus clouds are weakly correlated with low-level buoyancy, cloud depth, and cloud size.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Microstructural and preliminary optical and microwave characterization of erbium-doped CaMoO 4 thin films

This work explores erbium-doped calcium molybdate (Er:CaMoO4) thin films grown on silicon and yttria stabilized zirconia (YSZ) substrates, as a potential solid state system for C-band (utilizing the ∼1.5 μm Er 3+ 4f–4f transition) quantum emitters for quantum network applications. Through molecular beam epitaxial growth experiments and electron microscopy, X-ray diffraction, and reflection electron diffraction studies, we identify an incorporation limited deposition regime that enables a 1:1 Ca:Mo ratio in the growing film leading to single phase CaMoO 4 formation that can be in situ doped with Er (typically 2–100 ppm). We further show that growth on silicon substrates is single phase but polycrystalline in morphology, while growth on YSZ substrates leads to high-quality epitaxial single crystalline CaMoO 4 films. We perform preliminary optical and microwave characterization on the suspected Y 1 –Z 1 transition of 2 ppm, 200 nm epitaxial Er:CaMoO 4 annealed thin films and extract an optical inhomogeneous linewidth of 9.1(1) GHz, an optical excited state lifetime of 6.7(2) ms, a spectral diffusion-limited homogeneous linewidth of 6.7(4) MHz, and an EPR linewidth of 1.10(2) GHz.

Masiulionis, Ignas [Univ. of Chicago, IL (United S↗
DOE OSTI2021

Radial electric field and density fluctuations measured by Doppler reflectometry during the post-pellet enhanced confinement phase in W7-X

Radial profiles of density fluctuations and the radial electric field, Er, have been measured using Doppler reflectometry during the post-pellet enhanced confinement phase achieved, under different heating power levels and magnetic configurations, during the 2018 W7-X experimental campaign. A pronounced Er-well is measured with local values as high as -40 kV m -1 in the radial range ρ ~ 0.7–0.8 during the post-pellet enhanced confinement phase. The maximum Er intensity scales with both the plasma density and electron cyclotron heating power level, following a similar trend to the plasma energy content. A good agreement is found when the experimental Er profiles are compared to simulations carried out using the neoclassical codes, the drift kinetic equation solver (DKES) and kinetic orbit-averaging solver for stellarators (KNOSOS). The density fluctuation level decreases from the plasma edge toward the plasma core and the drop is more pronounced in the post-pellet enhanced confinement phase than in reference gas-fuelled plasmas. Besides, in the post-pellet phase, the density fluctuation level is lower in the high iota magnetic configuration than in the standard one. Therefore, to determine whether this difference is related to the differences in the plasma profiles or to the stability properties of the two configurations, gyrokinetic simulations have been carried out using the codes stella and EUTERPE. The simulation results point to the plasma profile evolution after the pellet injection and the stabilization effect of the radial electric field profile as the dominant players in the stabilization of the plasma turbulence.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2022

Substantial carbon loss respired from a corn–soybean agroecosystem highlights the importance of careful management as we adapt to changing climate

Understanding agroecosystem carbon (C) cycle response to climate change and management is vital for maintaining their long-term C storage. We demonstrate this importance through an in-depth examination of a ten-year eddy covariance dataset from a corn–corn–soybean crop rotation grown in the Midwest United States. Ten-year average annual net ecosystem exchange (NEE) showed a net C sink of –0.39 Mg C ha –1 yr –1 . However, NEE in 2014 and 2015 from the corn ecosystem was 3.58 and 2.56 Mg C ha –1 yr –1 , respectively. Most C loss occurred during the growing season, when photosynthesis should dominate and C fluxes should reflect a net ecosystem gain. Partitioning NEE into gross primary productivity (GPP) and ecosystem respiration (ER) showed this C 'burp' was driven by higher ER, with a 51% (2014) and 57% (2015) increase from the ten-year average (15.84 Mg C ha –1 yr –1 ). GPP was also higher than average (16.24 Mg C ha –1 yr –1 ) by 25% (2014) and 37% (2015), but this was not enough to offset the C emitted from ER. This increased ER was likely driven by enhanced soil microbial respiration associated with ideal growing season climate, substrate availability, nutrient additions, and a potential legacy effect from drought.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2022

Erbium-implanted materials for quantum communication applications

Erbium-doped materials can serve as spin-photon interfaces with optical transitions in the telecom C band, making them an exciting class of materials for long-distance quantum communication. However, the spin and optical coherence times of Er 3+ ions are limited by currently available host materials, motivating the development of new Er 3+ -containing materials. Here we demonstrate the use of ion implantation to efficiently screen prospective host candidates, and show that disorder introduced by ion implantation can be mitigated through post-implantation thermal processing to achieve inhomogeneous linewidths comparable to bulk linewidths in as-grown samples. We present optical spectroscopy data for each host material, which allows us to determine the level structure of each site, allowing us to compare the environments of Er 3+ introduced via implantation and via doping during growth. Here, we demonstrate that implantation can generate a range of local environments for Er 3+ , including those observed in bulk-doped materials, and that the populations of these sites can be controlled with thermal processing.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2022

Effects of collisional ion orbit loss on neoclassical tokamak radial electric fields

Ion orbit loss is considered important for generating the radially inward electric field Er in a tokamak edge plasma. In particular, this effect is emphasized in diverted tokamaks with a magnetic X point. In neoclassical equilibria, Coulomb collisions can scatter ions onto loss orbits and generate a radially outward current, which in steady state is balanced by the radially inward current from viscosity. To quantitatively measure this loss-orbit current in an edge pedestal, an ion-orbit-flux diagnostic has been implemented in the axisymmetric version of the gyrokinetic particle-in-cell code XGC. As the first application of this diagnostic, a neoclassical DIII-D H-mode plasma is studied using gyrokinetic ions and adiabatic electrons. The validity of the diagnostic is demonstrated by studying the collisional relaxation of Er in the core. After this demonstration, the loss-orbit current is numerically measured in the edge pedestal in quasisteady state. In this plasma, it is found that the radial electric force on ions from Er approximately balances the ion radial pressure gradient in the edge pedestal, with the radial force from the plasma flow term being a minor component. The effect of orbit loss on Er is found to be only mild.

gyrokinetic simulations↗
DOE OSTI2024

Digital Analytics, Causal Knowledge Acquisition and Reasoning for Technical Language Processing

Complex engineering systems such as nuclear power plants (NPPs) generate and collect large amounts of equipment reliability (ER) data elements that contain information on the status of components, assets, and systems. Some of this information is textual in form and can be found in documents such as incident reports (IRs) and work orders (WOs). Analyses of textual data in current NPPs-using natural language processing (NLP) methods-have been expanded over the last decade, and it is only recently that the true potential of such analyses has emerged. So far, applications of NLP methods have mostly been limited to classification and prediction, the goal being to identify the nature of the textual element (e.g., safety or non-safety related). Here, we target a more complex problem: automatically extracting knowledge from a textual element in order to assist system engineers in conducting system health assessments. Knowledge extraction is a very broad concept, and its definition may vary depending on the application context. Our methods are a blend of both rule-based and machine learning (ML) algorithms. For our purposes, knowledge extraction means identifying the systems or assets mentioned in a given textual element, as well as the type of event described (e.g., component failure or maintenance activity). In addition, we want to capture details such as measured quantities and the temporal/cause-effect relations between events. In this tool, we also demonstrate how textual data elements are preprocessed in order to handle typos, acronyms, and abbreviations. One main feature of these methods is that they are not based solely on data, but are in fact model-based. In other words, they also rely on MBSE models that are designed to capture-from a functional point of view-the architecture of the systems/assets under consideration. The main purpose of such models is to digitally emulate system engineers' knowledge of system and asset architecture and to identify dependencies among systems, assets, and components. Provided these models, analyses of textual and numeric ER data can be performed by first identifying the OPM model elements to which the ER data elements are referring. The relationships between ER data elements are then identified by checking for any temporal or logical dependencies.

Mandelli, Diego [Idaho National Laboratory (INL), ↗