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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 631 records · Page 35
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Studies of the outer-off-midplane lower hybrid wave launch scenario for plasma start-up on the TST-2 spherical tokamak

Abstract Establishment of an efficient central solenoid (CS) free tokamak plasma start-up method may lead to an economical fusion reactor. CS-free start-up using lower hybrid (LH) waves has been studied on the TST-2 spherical tokamak. Plasma current of about a quarter of CS-driven discharges has been obtained fully non-inductively using the outer-midplane and top LH launchers. Recently, an outer-off-midplane LH launcher was developed to achieve higher plasma current by optimizing for core absorption and minimal fast electron losses. Using the (outer-)off-midplane launcher, fully non-inductive plasma current start-up up to about 8 kA was achieved. Coupled ray-tracing and Fokker–Planck simulation was performed on equilibria reconstructed with an extended MHD model. It was found that the experimentally observed plasma current was in reasonable agreement with the numerical simulation. The simulation predicted appreciable orbit losses for the off-midplane launcher driven discharge at the present parameters, which was consistent with the experimentally observed x-ray radiation characteristics. The simulation showed that the current density was saturated for the present off-midplane launcher discharges and higher density and higher LH power was necessary to achieve higher plasma current.

Physics↗
DOE OSTI2019

Multi-scale structural analysis of proteins by deep semantic segmentation

Abstract Motivation Recent advances in computational methods have facilitated large-scale sampling of protein structures, leading to breakthroughs in protein structural prediction and enabling de novo protein design. Establishing methods to identify candidate structures that can lead to native folds or designable structures remains a challenge, since few existing metrics capture high-level structural features such as architectures, folds and conformity to conserved structural motifs. Convolutional Neural Networks (CNNs) have been successfully used in semantic segmentation—a subfield of image classification in which a class label is predicted for every pixel. Here, we apply semantic segmentation to protein structures as a novel strategy for fold identification and structure quality assessment. Results We train a CNN that assigns each residue in a multi-domain protein to one of 38 architecture classes designated by the CATH database. Our model achieves a high per-residue accuracy of 90.8% on the test set (95.0% average per-class accuracy; 87.8% average per-structure accuracy). We demonstrate that individual class probabilities can be used as a metric that indicates the degree to which a randomly generated structure assumes a specific fold, as well as a metric that highlights non-conformative regions of a protein belonging to a known class. These capabilities yield a powerful tool for guiding structural sampling for both structural prediction and design. Availability and implementation The trained classifier network, parser network, and entropy calculation scripts are available for download at https://git.io/fp6bd, with detailed usage instructions provided at the download page. A step-by-step tutorial for setup is provided at https://goo.gl/e8GB2S. All Rosetta commands, RosettaRemodel blueprints, and predictions for all datasets used in the study are available in the Supplementary Information. Supplementary information Supplementary data are available at Bioinformatics online.

Eguchi, Raphael R.↗
DOE OSTI2020

Analysis of a preQ1-I riboswitch in effector-free and bound states reveals a metabolite-programmed nucleobase-stacking spine that controls gene regulation

Abstract Riboswitches are structured RNA motifs that recognize metabolites to alter the conformations of downstream sequences, leading to gene regulation. To investigate this molecular framework, we determined crystal structures of a preQ1-I riboswitch in effector-free and bound states at 2.00 Å and 2.65 Å-resolution. Both pseudoknots exhibited the elusive L2 loop, which displayed distinct conformations. Conversely, the Shine-Dalgarno sequence (SDS) in the S2 helix of each structure remained unbroken. The expectation that the effector-free state should expose the SDS prompted us to conduct solution experiments to delineate environmental changes to specific nucleobases in response to preQ1. We then used nudged elastic band computational methods to derive conformational-change pathways linking the crystallographically-determined effector-free and bound-state structures. Pathways featured: (i) unstacking and unpairing of L2 and S2 nucleobases without preQ1—exposing the SDS for translation and (ii) stacking and pairing L2 and S2 nucleobases with preQ1—sequestering the SDS. Our results reveal how preQ1 binding reorganizes L2 into a nucleobase-stacking spine that sequesters the SDS, linking effector recognition to biological function. The generality of stacking spines as conduits for effector-dependent, interdomain communication is discussed in light of their existence in adenine riboswitches, as well as the turnip yellow mosaic virus ribosome sensor.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2016

INTEGRATION OF PANDA WORKLOAD MANAGEMENT SYSTEM WITH SUPERCOMPUTERS

Abstract The Large Hadron Collider (LHC), operating at the international CERN Laboratory in Geneva, Switzerland, is leading Big Data driven scientific explorations. Experiments at the LHC explore the funda- mental nature of matter and the basic forces that shape our universe, and were recently credited for the dis- covery of a Higgs boson. ATLAS, one of the largest collaborations ever assembled in the sciences, is at the forefront of research at the LHC. To address an unprecedented multi-petabyte data processing challenge, the ATLAS experiment is relying on a heterogeneous distributed computational infrastructure. The ATLAS experiment uses PanDA (Production and Data Analysis) Workload Management System for managing the workflow for all data processing on over 140 data centers. Through PanDA, ATLAS physicists see a single computing facility that enables rapid scientific breakthroughs for the experiment, even though the data cen- ters are physically scattered all over the world. While PanDA currently uses more than 250000 cores with a peak performance of 0.3+ petaFLOPS, next LHC data taking runs will require more resources than Grid computing can possibly provide. To alleviate these challenges, LHC experiments are engaged in an ambitious program to expand the current computing model to include additional resources such as the opportunistic use of supercomputers. We will describe a project aimed at integration of PanDA WMS with supercomputers in United States, Europe and Russia (in particular with Titan supercomputer at Oak Ridge Leadership Com- puting Facility (OLCF), Supercomputer at the National Research Center Kurchatov Institute , IT4 in Ostrava, and others). The current approach utilizes a modified PanDA pilot framework for job submission to the supercomputers batch queues and local data management, with light-weight MPI wrappers to run single- threaded workloads in parallel on Titan s multi-core worker nodes. This implementation was tested with a variety of Monte-Carlo workloads on several supercomputing platforms. We will present our current accom- plishments in running PanDA WMS at supercomputers and demonstrate our ability to use PanDA as a portal independent of the computing facility s infrastructure for High Energy and Nuclear Physics, as well as other data-intensive science applications, such as bioinformatics and astro-particle physics.

De, K↗
DOE OSTI2021

Minnesota peat viromes reveal terrestrial and aquatic niche partitioning for local and global viral populations

Abstract Background Peatlands are expected to experience sustained yet fluctuating higher temperatures due to climate change, leading to increased microbial activity and greenhouse gas emissions. Despite mounting evidence for viral contributions to these processes in peatlands underlain with permafrost, little is known about viruses in other peatlands. More generally, soil viral biogeography and its potential drivers are poorly understood at both local and global scales. Here, 87 metagenomes and five viral size-fraction metagenomes (viromes) from a boreal peatland in northern Minnesota (the SPRUCE whole-ecosystem warming experiment and surrounding bog) were analyzed for dsDNA viral community ecological patterns, and the recovered viral populations (vOTUs) were compared with our curated PIGEON database of 266,125 vOTUs from diverse ecosystems. Results Within the SPRUCE experiment, viral community composition was significantly correlated with peat depth, water content, and carbon chemistry, including CH 4 and CO 2 concentrations, but not with temperature during the first 2 years of warming treatments. Peat vOTUs with aquatic-like signatures (shared predicted protein content with marine and/or freshwater vOTUs) were significantly enriched in more waterlogged surface peat depths. Predicted host ranges for SPRUCE vOTUs were relatively narrow, generally within a single bacterial genus. Of the 4326 SPRUCE vOTUs, 164 were previously detected in other soils, mostly peatlands. None of the previously identified 202,371 marine and freshwater vOTUs in our PIGEON database were detected in SPRUCE peat, but 0.4% of 80,714 viral clusters (VCs, grouped by predicted protein content) were shared between soil and aquatic environments. On a per-sample basis, vOTU recovery was 32 times higher from viromes compared with total metagenomes. Conclusions Results suggest strong viral “species” boundaries between terrestrial and aquatic ecosystems and to some extent between peat and other soils, with differences less pronounced at higher taxonomic levels. The significant enrichment of aquatic-like vOTUs in more waterlogged peat suggests that viruses may also exhibit niche partitioning on more local scales. These patterns are presumably driven in part by host ecology, consistent with the predicted narrow host ranges. Although more samples and increased sequencing depth improved vOTU recovery from total metagenomes, the substantially higher per-sample vOTU recovery after viral particle enrichment highlights the utility of soil viromics.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Modeling anaerobic soil organic carbon decomposition in Arctic polygon tundra: insights into soil geochemical influences on carbon mineralization

Abstract. Rapid warming of Arctic ecosystems exposes soil organic matter (SOM) to accelerated microbial decomposition, potentially leading to increased emissions of carbon dioxide ( CO 2 ) and methane ( CH 4 ) that have a positive feedback on global warming. Current estimates of the magnitude and form of carbon emissions from Earth system models include significant uncertainties, partially due to the oversimplified representation of geochemical constraints on microbial decomposition. Here, we coupled modeling principles developed in different disciplines, including a thermodynamically based microbial growth model for methanogenesis and iron reduction, a pool-based model to represent upstream carbon transformations, and a humic ion-binding model for dynamic pH simulation to build a more versatile carbon decomposition model framework that can be applied to soils under varying redox conditions. This new model framework was parameterized and validated using synthesized anaerobic incubation data from permafrost-affected soils along a gradient of fine-scale thermal and hydrological variabilities across Arctic polygonal tundra. The model accurately simulated anaerobic CO 2 production and its temperature sensitivity using data on labile carbon pools and fermentation rates as model constraints. CH 4 production is strongly influenced by water content, pH, methanogen biomass, and presence of competing electron acceptors, resulting in high variability in its temperature sensitivity. This work provides new insights into the interactions of SOM pools, temperature increase, soil geochemical feedbacks, and resulting CO 2 and CH 4 production. The proposed anaerobic carbon decomposition framework presented here builds a mechanistic link between soil geochemistry and carbon mineralization, making it applicable over a wide range of soils under different environmental settings.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2015

Structure of oxides prepared by decomposition of layered double Mg–Al and Ni–Al hydroxides

Abstracts: Thermal decomposition of Mg–Al and Ni–Al layered double hydroxides LDH at temperatures lower than 800 °C leads to the formation of oxides with different structures. Mg–Al oxide has a very defective structure and consists of octahedral layers as in periclase MgO and mixed octahedral–tetrahedral layers as in spinel MgAl{sub 2}O{sub 4}. Mixed Ni–Al oxide has a sandwich-like structure, consisting of a core with Al-doped NiO-like structure and some surface layers with spinel NiAl{sub 2}O{sub 4} structure epitaxial connected with the core. Suggested models were verified by simulation of X-ray diffraction patterns using DIFFaX code, as well as HRTEM, IR-, UV-spectroscopies, and XPS. - Graphical abstract: In the Mg–Al layered double hydroxide Al{sup 3+} ions migrate into interlayers during decomposition. The Mg–Al oxide represents sequence of octahedral and octahedral–tetrahedral spinel layers with vacancies. The Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers as a result of migration of Al{sup 3+} ions on the surface. The models explain the presence and absence of “memory effect” for the Mg–Al and Ni–Al oxides, respectively. - Highlights: • We study products of Mg(Ni)–Al LDH decomposition by calcination at 500(400)–800 °C. • In Mg–Al/Ni–Al LDH Al ions migrate into interlayers/on the surface during decomposition. • Mg–Al oxide represents sequence of periclase- and spinel-like layers with vacancies. • Ni–Al oxide has a sandwich-like structure with NiO-like core and surface spinel layers. • The models explain the presence/absence of “memory effect” for Mg–Al/Ni–Al oxides.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Ionic and Optical Properties of Methylammonium Lead Iodide Perovskite across the Tetragonal–Cubic Structural Phase Transition

Abstract Practical hybrid perovskite solar cells (PSCs) must endure temperatures above the tetragonal–cubic structural phase transition of methylammonium lead iodide (MAPbI 3 ). However, the ionic and optical properties of MAPbI 3 in such a temperature range, and particularly, dramatic changes in these properties resulting from a structural phase transition, are not well studied. Herein, we report a striking contrast at approximately 45 °C in the ionic/electrical properties of MAPbI 3 owing to a change of the ion activation energy from 0.7 to 0.5 eV, whereas the optical properties exhibit no particular transition except for the steady increase of the bandgap with temperature. These observations can be explained by the “continuous” nature of perovskite phase transition. We speculate that the critical temperature at which the ionic/electrical properties change, although related to crystal symmetry variation, is not necessarily the same temperature as when tetragonal–cubic structural phase transition occurs.

Hoque, Md Nadim Ferdous↗
DOE OSTI2014

Brain derived neurotrophic factor is involved in the regulation of glycogen synthase kinase 3β (GSK3β) signalling

Highlights: • BDNF knockdown leads to activation of GSK3β in the neuronal cells. • BDNF knockdown can induce GSK3β activation beyond TrkB mediated effects. • BDNF impairment in vivo leads to age dependent activation of GSK3β in the retina. • Systemic treatment with TrkB agonist induces inhibition of retinal GSK3β. - Abstract: Glycogen synthase kinase 3β (GSK3β) is involved in several biochemical processes in neurons regulating cellular survival, gene expression, cell fate determination, metabolism and proliferation. GSK3β activity is inhibited through the phosphorylation of its Ser-9 residue. In this study we sought to investigate the role of BDNF/TrkB signalling in the modulation of GSK3β activity. BDNF/TrkB signalling regulates the GSK3β activity both in vivo in the retinal tissue as well as in the neuronal cells under culture conditions. We report here for the first time that BDNF can also regulate GSK3β activity independent of its effects through the TrkB receptor signalling. Knockdown of BDNF lead to a decline in GSK3β phosphorylation without having a detectable effect on the TrkB activity or its downstream effectors Akt and Erk1/2. Treatment with TrkB receptor agonist had a stimulating effect on the GSK3β phosphorylation, but the effect was significantly less pronounced in the cells in which BDNF was knocked down. The use of TrkB receptor antagonist similarly, manifested itself in the form of downregulation of GSK3β phosphorylation, but a combined TrkB inhibition and BDNF knockdown exhibited a much stronger negative effect. In vivo, we observed reduced levels of GSK3β phosphorylation in the retinal tissues of the BDNF{sup +/−} animals implicating critical role of BDNF in the regulation of the GSK3β activity. Concluding, BDNF/TrkB axis strongly regulates the GSK3β activity and BDNF also exhibits GSK3β regulatory effect independent of its actions through the TrkB receptor signalling.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2019

Thermal Conductivity and Phonon Scattering Processes of ALD Grown PbTe–PbSe Thermoelectric Thin Films

Abstract This work studies the thermal conductivity and phonon scattering processes in a series of n‐type lead telluride‐lead selenide (PbTe–PbSe) nanostructured thin films grown by atomic layer deposition (ALD). The ALD growth of the PbTe–PbSe samples in this work results in nonepitaxial films grown directly on native oxide/Si substrates, where the Volmer–Weber mode of growth promotes grains with a preferred columnar orientation. The ALD growth of these lead‐rich PbTe, PbSe, and PbTe–PbSe thin films results in secondary oxide phases, along with an increase microstructural quality with increased film thickness. The compositional variation and resulting point and planar defects in the PbTe–PbSe nanostructures give rise to additional phonon scattering events that reduce the thermal conductivity below that of the corresponding ALD‐grown control PbTe and PbSe films. Temperature‐dependent thermal conductivity measurements show that the phonon scattering in these ALD‐grown PbTe–PbSe nanostructured materials, along with ALD‐grown PbTe and PbSe thin films, are driven by extrinsic defect scattering processes as opposed to phonon–phonon scattering processes intrinsic to the PbTe or PbSe phonon spectra. The implication of this work is that polycrystalline, nanostructured ALD composites of thermoelectric PbTe–PbSe films are effective in reducing the phonon thermal conductivity, and represent a pathway for further improvement of the figure of merit ( ZT ), enhancing their thermoelectric application potential.

DeCoster, Mallory E.↗
DOE OSTI2023

Halide Perovskites and Their Derivatives for Efficient, High‐Resolution Direct Radiation Detection: Design Strategies and Applications

Abstract The past decade has witnessed a rapid rise in the performance of optoelectronic devices based on lead‐halide perovskites (LHPs). The large mobility‐lifetime products and defect tolerance of these materials, essential for optoelectronics, also make them well‐suited for radiation detectors, especially given the heavy elements present, which is essential for strong X‐ray and γ‐ray attenuation. Over the past decade, LHP thick films, wafers, and single crystals have given rise to direct radiation detectors that have outperformed incumbent technologies in terms of sensitivity (reported values up to 3.5 × 10 6 µC Gy air −1 cm −2 ), limit of detection (directly measured values down to 1.5 nGy air s −1 ), along with competitive energy and imaging resolution at room temperature. At the same time, lead‐free perovskite‐inspired materials (e.g., methylammonium bismuth iodide), which have underperformed in solar cells, have recently matched and, in some areas (e.g., in polarization stability), surpassed the performance of LHP detectors. These advances open up opportunities to achieve devices for safer medical imaging, as well as more effective non‐invasive analysis for security, nuclear safety, or product inspection applications. Herein, the principles behind the rapid rises in performance of LHP and perovskite‐inspired material detectors, and how their properties and performance link with critical applications in non‐invasive diagnostics are discussed. The key strategies to engineer the performance of these materials, and the important challenges to overcome to commercialize these new technologies are also discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Advanced wind turbine control development using field test analysis for generator overspeed mitigation

Abstract Turbulent and gusty wind conditions can cause generator overspeed peaks to exceed a threshold that then lead to wind turbine shutdowns, which then decrease the energy production of the wind turbines. We derive so‐called “gust measures” that predict when generator overspeed peaks may occur. These gust measures are then used to develop advanced controllers to mitigate generator overspeed peaks so that wind turbines can operate more robustly in difficult wind conditions without exceeding generator overspeed thresholds that would lead to turbine shutdown events. The advanced controllers are demonstrated in nonlinear aeroelastic simulations using the open‐source wind turbine simulation tool OpenFAST. To increase the realism of the simulations, they are run using field‐replicated wind conditions and a wind turbine model based on data from an experimental field campaign on a downscaled demonstrator of a novel extreme‐scale, two‐bladed, downwind rotor design.

17 WIND ENERGY↗
DOE OSTI2013

Distinct physiological roles for the two L-asparaginase isozymes of Escherichia coli

Highlights: •Escherichia coli contains two L-asparaginase isozymes with distinct localization, kinetics and regulation. •Mutant strains were used to examine the roles of these enzymes in L-asparagine utilization. •We report that L-asparaginase II permits growth on asparagine and glycerol under anaerobic conditions. •We propose that this enzyme is the first step in a co-regulated pathway leading to fumarate. •The pathway is regulated by anaerobiosis and cAMP and provides a terminal elector acceptor. -- Abstract: Escherichia coli expresses two L-asparaginase (EC 3.5.1.1) isozymes: L-asparaginse I, which is a low affinity, cytoplasmic enzyme that is expressed constitutively, and L-asparaginase II, a high affinity periplasmic enzyme that is under complex co-transcriptional regulation by both Fnr and Crp. The distinct localisation and regulation of these enzymes suggest different roles. To define these roles, a set of isogenic mutants was constructed that lacked either or both enzymes. Evidence is provided that L-asparaginase II, in contrast to L-asparaginase I, can be used in the provision of an anaerobic electron acceptor when using a non-fermentable carbon source in the presence of excess nitrogen.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Cadmium induces vascular permeability via activation of the p38 MAPK pathway

Highlights: • Low-dose cadmium (Cd) induces vascular hyper-permeability. • p38 MAPK mediates Cd-induced disruption of endothelial cell barrier function. • SB203850 inhibits Cd-induced membrane dissociation of VE-cadherin and β-catenin. • SB203850 reduces Cd-induced expression and secretion of TNF-α. - Abstract: The vasculature of various organs is a targeted by the environmental toxin, cadmium (Cd). However, mechanisms leading to pathological conditions are poorly understood. In the present study, we examined the effect of cadmium chloride (CdCl{sub 2}) on human umbilical vein endothelial cells (HUVECs). At 4 μM, CdCl{sub 2} induced a hyper-permeability defect in HUVECs, but not the inhibition of cell growth up to 24 h. This effect of CdCl{sub 2} was dependent on the activation of the p38 mitogen-activated protein kinase (MAPK) pathway. The p38 MAPK inhibitor SB203850 suppressed the CdCl{sub 2}-induced alteration in trans-endothelial electrical resistance in HUVEC monolayers, a model measurement of vascular endothelial barrier integrity. SB203850 also inhibited the Cd-induced membrane dissociation of vascular endothelial (VE) cadherin and β-catenin, the important components of the adherens junctional complex. In addition, SB203850 reduces the Cd-induced expression and secretion of tumor necrosis factor α (TNF-α). Taken together, our findings suggest that Cd induces vascular hyper-permeability and disruption of endothelial barrier integrity through stimulation of p38 MAPK signaling.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

A combined experimental and theoretical study of the supramolecular self-assembly of Cu(II) malonate complex assisted by various weak forces and water dimer

A Cu(II) malonate complex with formula [Cu(C{sub 3}H{sub 2}O{sub 4})(C{sub 6}H{sub 8}N{sub 2})(H{sub 2}O)]{sub 2}·4H{sub 2}O (1) [C{sub 6}H{sub 8}N{sub 2}=2-picolylamine, C{sub 3}H{sub 2}O{sub 4}{sup 2−}=malonate dianion] has been synthesized by mixing the reactants in their stoichiometric proportion and its crystal structure has been determined by single-crystal X-ray diffraction. In 1, monomeric neutral metal malonate units [Cu(C{sub 3}H{sub 2}O{sub 4})(C{sub 6}H{sub 8}N{sub 2})(H{sub 2}O)] are interlinked with each other through hydrogen bonds, weak lone pair⋯π and cuprophilic interactions to generate supramolecular dimers, which in turn further associated through hydrogen bonding to form infinite 1D chains. Water dimers, through series of hydrogen bonds and weak π–stacking forces are found to be responsible for interconnection of 1D chains, which resulted in a 3D network. A density functional (DFT) study of the energetic features of several noncovalent interactions observed in the solid state have been analyzed and characterized using Bader's theory of “atoms-in-molecules”. We also present here Hirshfeld surface analysis to investigate the close intermolecular contacts. - Graphical Abstract: Interplay of weak forces like hydrogen bonding, lone pair⋯π, Cu⋯Cu and π–stacking interactions leading to the formation of supramolecular network in [Cu(C{sub 3}H{sub 2}O{sub 4})(C{sub 6}H{sub 8}N{sub 2})(H{sub 2}O)]{sub 2}·4H{sub 2}O complex. - Highlights: • A complex of Cu(II) with malonate and 2-picolylamine is synthesized and X-ray characterized. • We report a density functional study of the energetic features of several noncovalent interactions • We perform Hirshfeld surface analysis to investigate the close intermolecular contacts.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2016

Ag{sup II} doped MIL-101 and its adsorption of iodine with high speed in solution

In order to improve the adsorption speed of iodine from water, MIL-101 with extra-large specific surface area (3054 m{sup 2}/g) was chosen as a base material, and then, Ag was doped into MIL-101 to enhance its adsorption capacity through an incipient-wetness impregnation method. With the characterization of SEM-EDS, TEM, XRD, XPS, TGA, IR, and BET techniques, the resulting Ag was identified to be stay in the framework of MIL-101 stably in the form of Ag{sup II} (generally, Ag{sup II} cation is not stable). However, after the adsorption of I{sup −} anions, Ag{sup II} stay in the cages of MIL-101 in the form of AgI/AgI{sub 3}. It is important to note that, all adsorbents show high adsorption speed of iodine in solution. The equilibrium adsorption time of the adsorbents were acquired by only a few minutes, which can be attributed to its large BET surface area. An interesting note is that, when the doping amount of Ag is less than 9%, the iodine anions adsorption capacity of Ag@MIL-101 is greater than its theoretical adsorption capacity. It shows that both physical adsorption and chemical adsorption are existed in the adsorption process. This study hopefully leads to a new and highly efficient Ag-based adsorbent for iodide adsorb from solutions. - Graphical abstract: Ag{sup II} stay in the framework of MIL-101 stably because of F{sup -}, after the adsorption of I{sup -} anions, Ag{sup I}I /Ag{sup I}I{sub 3} stay in the cages of MIL-101. The equilibrium adsorption time of Ag@MIL-101 were acquired by only a few minutes. - Highlights: • Ag{sup II} was doped into MIL-101 by an incipient-wetness impregnation method. • Both physical adsorption and chemical adsorption are verified in the adsorption process. • Ag@MIL-101 exhibits high adsorption speed and adsorption capacity. • Ag@MIL-101 can be effectively applied to the removal of radioactive iodide anions from water in acidic and neutral medium.

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

Mixed nickel-gallium tellurides Ni{sub 3−x}GaTe{sub 2} as a matrix for incorporating magnetic cations: A Ni{sub 3−x}Fe{sub x}GaTe{sub 2} series

Using a high-temperature ampoule technique, a series of mixed nickel-iron-gallium metal-rich tellurides with layered structures, Ni{sub 3-x}Fe{sub x}GaTe{sub 2}, were prepared and characterized based on X-ray powder diffraction, energy-dispersive spectroscopy, and {sup 57}Fe Mössbauer spectroscopy data. These compounds may be regarded as a result of partial substitution of nickel by iron in the recently reported ternary Ni{sub 3-x}GaTe{sub 2} series, which are based on NiAs/Ni{sub 2}In type of structure. The compositional boundary for the substitution was found to be at x~1. According to the Mössbauer spectroscopy data, the substitution is not statistical, and iron atoms with the increase in x tend to preferentially occupy those nickel positions that are partially vacant in the initial ternary compound. Magnetic measurements data for the Ni{sub 3-x}Fe{sub x}GaTe{sub 2} series show dramatic change in behavior from temperature-independent paramagnetic properties of the initial matrix to a low-temperature (~75 K) ferromagnetic ordering in the Ni{sub 2}FeGaTe{sub 2}. - Graphical abstract: Ordered substitution of nickel by iron in the Ni{sub 3−x}GaTe{sub 2} series leading to ferromagnetic ordering. - Highlights: • A series of Ni{sub 3−x}Fe{sub x}GaTe{sub 2} compounds were synthesized. • They adopt the NiAs/Ni{sub 2}In type of structure with ordered iron distribution. • The distribution of iron was studied using {sup 57}Fe Mössbauer spectroscopy. • An increase in iron content leads to the strong ferromagnetic coupling.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗