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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 541 records · Page 30
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Atomic layer deposition of boron-containing films using B{sub 2}F{sub 4}

Ultrathin and conformal boron-containing atomic layer deposition (ALD) films could be used as a shallow dopant source for advanced transistor structures in microelectronics manufacturing. With this application in mind, diboron tetrafluoride (B{sub 2}F{sub 4}) was explored as an ALD precursor for the deposition of boron containing films. Density functional theory simulations for nucleation on silicon (100) surfaces indicated better reactivity of B{sub 2}F{sub 4} in comparison to BF{sub 3}. Quartz crystal microbalance experiments exhibited growth using either B{sub 2}F{sub 4}-H{sub 2}O for B{sub 2}O{sub 3} ALD, or B{sub 2}F{sub 4}-disilane (Si{sub 2}H{sub 6}) for B ALD, but in both cases, the initial growth per cycle was quite low (≤0.2 Å/cycle) and decreased to near zero growth after 8–30 ALD cycles. However, alternating between B{sub 2}F{sub 4}-H{sub 2}O and trimethyl aluminum (TMA)-H{sub 2}O ALD cycles resulted in sustained growth at ∼0.65 Å/cycle, suggesting that the dense –OH surface termination produced by the TMA-H{sub 2}O combination enhances the uptake of B{sub 2}F{sub 4} precursor. The resultant boron containing films were analyzed for composition by x-ray photoelectron spectroscopy, and capacitance measurements indicated an insulating characteristic. Finally, diffused boron profiles less than 100 Å were obtained after rapid thermal anneal of the boron containing ALD film.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Quantum Chemical Approach for Calculating Stability Constants of Mercury Complexes

Stability constants are central to the multi-scale modeling of the thermodynamic speciation, cycling, and transport of mercury (Hg) and other contaminants in aquatic environments. However, for Hg, experimental values for many relevant complexes are not available, and for others can span ranges in excess of 10 log units. The missing data and large uncertainties mean there are significant knowledge gaps in predictions of thermodynamic speciation. As an alternative to experimental measurements, thermodynamic quantities can be calculated with quantum chemical methods. Among these, density functional theory (DFT) with a polarizable continuum solvent combines accuracy with practicability. In this paper, we present an accurate and quick approach in which we use DFT with continuum solvation to calculate stability constants of Hg complexes with inorganic and low molecular-weight organic ligands in aqueous solution. Specifically, we use the M06/[SDD]6-31+G(d,p) level of theory in combination with a modified version of the SMD solvent model in which the solute radii are re-optimized with a scaled solvent-accessible surface (sSAS) approach. For the set of 37 Hg complexes used for optimization, which contain environmentally relevant functional groups and have reliable experimental stability constants, we obtain a mean unsigned error of 1.4 log units. Testing the method on an independent set of 12 Hg complexes reproduces the experimental stability constants to a mean unsigned error of 1.6 log units. Finally, this approach is a substantial step toward generally applicable rapid stability constant derivation for a wide range of Hg complexes, including those present in dissolved organic matter.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Geochemical characterization of floodplain sediments from Meander C and O in the East River Watershed, CO, USA

This data package is part of the Watershed Function SFA data collection and contains geochemical characterization of sediments as a function of depth in the pumphouse vicinity, including Meander C and Meander O (oxbow). This data was used in the manuscript "Fox, P.M., Bill, M., Heckman, K., Conrad, M., Anderson, C., Keiluweit, M., and Nico, P.S.Shale as a Source of Organic Carbon in Floodplain Sediments of a Mountainous Watershed" published in Journal of Geophysical Research: Biogeosciences. Data includes sieving, total organic carbon (TOC), total inorganic carbon (TIC), total nitrogen (TN), carbon isotopes (14C and 13C) of whole sediment. Sediment density fractionation data is also included, with measurements of TOC, TN, 14C and 13C on density fractions. Metal and carbon concentrations from various sediment extractions (HCl, dithionite, oxalate, water, and pyrophosphate) are included. Characterization of extracted carbon by fourier transform infrared spectroscopy (FTIR) and UV-Visible light spectroscopy. Characterization of density fractionated (light fractions) organic carbon by FTIR. Carbon X-ray spectroscopy (C near edge X-ray absorption fine structure spectroscopy [NEXAFS] and scanning transmission X-ray microscopy [STXM]) is also included for shale samples and sediment samples.Additional acknowledgements:1. M.K. and C.A. were supported by the Department of Energy, Office of Biological and Environmental Research, Subsurface Biosphere Research program (award no. DE-SC0016544).2. STXM and NEXAFS data was collected at the Canadian Light Source, which is supported by the Canada Foundation for Innovation, Natural Sciences and Engineering Research Council of Canada, the University of Saskatchewan, the Government of Saskatchewan, Western Economic Diversification Canada, the National Research Council Canada, and the Canadian Institutes of Health Research.3. Radiocarbon analysis was supported in part by the Radiocarbon Collaborative, which is jointly sponsored by the USDA Forest Service Northern Research Station, the KCCAMS Facility at UC Irvine, and Michigan Technological University.Update 11/06/2019: An .kml file was added with the GPS locations for all the sampling sites.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2026

Advancing Porous Carbons: Understanding the Importance of Surface Chemistry for the Energy–Environment Nexus

This review intends, in a critical way, the comprehensive view of the importance of porous carbons surface chemistry for their applications in an energy− environment nexus. Surface chemistry is presented as a combination of functional heteroatom-containing groups, dopants, and structural defects. First, we briefly address carbon surface chemical environment and the methods of its modification and characterization, indicating their practical limitations. Then, the effects of surface chemistry on separation, catalysis, energy storage, sensing and microwave absorption are introduced. Besides a critical analysis of published findings on these topics, we also include our views on the advancement in the processes which rely on porous carbons surface chemistry, and identify strategic areas and directions that should deserve further attention. We focus on new findings and important original contributions to the field. Since the community of carbon researchers grows following the strategic application of these materials, the role of functional groups, dopants and structural defects in various cutting-edge applications is emphasized, showing the progress in the field and the evolution of findings. A clear determination of the effects of carbon surface is often a challenge since carbons porosity and the locations of specific bonds/sites/ defects in the carbon texture provide nanoconfinement effects.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2014

Enzyme Design From the Bottom Up: An Active Nickel Electrocatalyst with a Structured Peptide Outer Coordination Sphere

Functional, peptide-containing metal complexes with a well-defined peptide structure have the potential to enhance molecular catalysts via an enzyme-like outer coordination sphere. Here, we report the synthesis and characterization of an active, peptide-based metal complex built upon the well characterized hydrogen production catalyst, Ni(PPh2NPh)2. The incorporated peptide maintains its B-hairpin structure when appended to the metal core, and the electrocatalytic activity of the peptide-based metal complex (~100,000 s-1) is fully retained. The combination of an active molecular catalyst with a structured peptide outer coordination sphere provides a scaffold that permits the incorporation of features of an enzyme-like outer-coordination sphere necessary to create molecular electrocatalysts with en-hanced functionality.

bioinspired↗
DOE OSTI2018

DN604: A platinum(II) drug candidate with classic SAR can induce apoptosis via suppressing CK2-mediated p-cdc25C subcellular localization in cancer cells

Highlights: • DN604 exhibited stronger comparable cytotoxicity to cisplatin. • DN604 showed more potent in vivo antitumor activity than carboplatin. • DN604 resulted in negligible toxic effects as the same effect as cisplatin in vivo. • DN604 could suppress CK2-induced p-cdc25C activation and subcellular localization. DN604, a carboplatin analogue with a functional dicarboxylato ligand, was deeply investigated to explore its ability to induce apoptosis as well as its antitumor mechanism of action. Both in vitro and in vivo assays indicated that DN604 could effectively inhibit cell viability of SGC-7901 gastric cancer cells and exhibited stronger antitumor activity than carboplatin and comparable activity to cisplatin. Significantly in contrast to cisplatin, DN604 resulted in negligible toxic effects in vivo with the same tumor growth inhibition effect as cisplatin. The mechanism study indicated that DN604 inhibited CK2-phosphorylated cdc25C activation to decrease p-cdc25C subcellular localization, leading to the inactivation of cdc2/Cyclin B and G2/M cell cycle arrest and apoptosis in SGC-7901 cancer cells. Our research revealed for the first time that the dicarboxylato ligand containing a suitable functional moiety as the leaving group in the platinum(II) complex can effectively induce cell cycle arrest and apoptosis via inhibiting key checkpoint proteins.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2015

Approximate expression for the electric potential around an absorbing particle in isotropic collisionless plasma

A new approximate expression for the potential distribution around an absorbing particle in isotropic collisionless plasma is proposed. The approximate expression is given by the sum of the Debye-Hückel potential with an effective screening length and the far-field asymptote obtained from the solution of the linearized Poisson equation. In contrast to analogous models, the effective screening length is not fixed but depends on the distance from the particle. This allows us to obtain a more accurate approximation for the potential distribution in the entire range of distances. The dependence of the screening length on the distance is predicted from the analysis of the charge density distribution function. This dependence contains two adjustable parameters, which are calculated by applying the procedure based on charge balance considerations. Using the obtained results, simple expressions for the parameters of the model are proposed. In addition, a simple expression for the characteristic screening length, which can be used to approximate the potential distribution near the particle, is obtained. The developed model potential is shown to be in excellent agreement with the solution of the nonlinear Poisson equation for typical conditions used in experiments with complex plasmas.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

Chemometric optimisation of pressurised liquid extraction for the determination of alliin and S‐allyl‐cysteine in giant garlic ( Allium ampeloprasum L.) by liquid chromatography tandem mass spectrometry

Abstract Introduction Giant garlic is a functional food that contains different kinds of bioactive molecules with beneficial effects on chronic noncommunicable diseases like diabetes and cardiovascular conditions. Considering biosynthesis pathways, abundance, and biological activity, alliin and S‐allyl‐cysteine were used as chemical markers of organosulphur compounds present in giant garlic. Objective To establish a chemometric optimisation of pressurised liquid extraction for the determination of alliin and S‐allyl‐cysteine in giant garlic by liquid chromatography tandem mass spectrometry (LC–MS/MS). Methodology Samples were blanched (ca. 90°C for 10 min) to inactivate alliinase and γ‐glutamyl transpeptidase enzymes and then freeze‐dried. Chemometric optimisation was performed via response surface methodology based on central composite design (CCD). Organosulphur compound yields were determined applying a validated LC–MS/MS method in multiple reaction monitoring (MRM) mode using the following transitions: for alliin m/z 178 → 74 and for S‐allyl‐cysteine m/z 162 → 41. Results According to CCD results, under constant conditions of pressure (1500 psi) and time (20 min), the optimal conditions for pressurised liquid extraction of alliin and S‐allyl‐cysteine were 70.75 and 68.97% v/v of ethanol in extraction solvent and 76.45 and 98.88°C as extraction temperature, respectively. Multiple response optimisation for the simultaneous extraction of both organosulphur compounds was established via desirability function. Under these conditions, 2.70 ± 0.27 mg g −1 dry weight (DW) of alliin and 2.79 ± 0.22 mg g −1 DW of S‐allyl‐cysteine were extracted. Conclusions These results clearly demonstrated that pressurised liquid extraction is an efficient green technique to extract bioactive organosulphur compounds from giant garlic. Extraction yields were significantly ( p < 0.05) higher than those obtained with conventional ultra‐turrax extraction.

Peterssen‐Fonseca, Darlene↗
DOE OSTI2024

Shrub Seedling Experiment: Environmental Conditions, Vegetation Composition, and Seedling Recruitment, Seward Peninsula, Alaska, 2018-2019

In June 2018, a manipulative seed-addition experiment was established at the Council Mile Marker 71 (CN_MM71), Quartz Creek Burn Area (Kougarok Mile Marker 86), and Quartz Creek Unburned (Kougarok Mile Marker 80) sites on the Seward Peninsula, Alaska. At each site, 5 replicate blocks were established in disturbed and intact upland tussock tundra (a total of 40 plots). Disturbed plots at Council were located on thermo-erosional (thermokarst) slopes, while disturbed plots in Quartz Creek were in burned areas affected by the Mingvk Lake fire in 2015. Using a split-plot design, an additional manual disturbance treatment (scraping to remove the surface bryophyte layer) was implemented across all blocks in June 2018. Seeds of five erect, deciduous shrubs were broadcast seeded into each plot in June 2018, and seedlings were censused in August 2018 and August 2019. The dataset includes ancillary measurements of plot-level environmental conditions (soil temperature, moisture, chemistry, thaw depth, microtopography, substrate thickness) and vegetation composition (NDVI and estimated percent cover by species and plant functional type). Dataset contains 10 csv data files (five data files with corresponding data dictionaries and one file-level metadata file) and one pdf user guide. The Next-Generation Ecosystem Experiments: Arctic (NGEE Arctic), was research effort to reduce uncertainty in Earth System Models by developing a predictive understanding of carbon-rich Arctic ecosystems and feedbacks to climate. NGEE Arctic was supported by the Department of Energy's Office of Biological and Environmental Research. The NGEE Arctic project had two field research sites: 1) located within the Arctic polygonal tundra coastal region on the Barrow Environmental Observatory (BEO) and the North Slope near Utqiagvik (Barrow), Alaska and 2) multiple areas on the discontinuous permafrost region of the Seward Peninsula north of Nome, Alaska. Through observations, experiments, and synthesis with existing datasets, NGEE Arctic provided an enhanced knowledge base for multi-scale modeling and contributed to improved process representation at global pan-Arctic scales within the Department of Energy's Earth system Model (the Energy Exascale Earth System Model, or E3SM), and specifically within the E3SM Land Model component (ELM).

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2016

Facilitated Ion Transport in Smectic Ordered Ionic Liquid Crystals

We investigated a novel ionic mixture of an imidazolium-based room temperature IL containing ethylene oxide functionalized phosphite anion and a lithium salt that self-assembles into a smectic-ordered IL crystal. The two key features in this work are the unique origin of the smectic order of the ionic mixtures and the facilitated ion transport behavior in the smectic ordered IL crystal. In fact, the IL crystals are self-assembled through Coulombic interactions between ion species, not through the hydrophilic-phobic interactions between charged ion heads and hydrophobic long alkyl pendants or the steric interaction between mesogenic moieties. Furthermore, the smectic order in the IL crystal ionogel facilitates exceptional and remarkable ionic transport. Large ionic conductivity, viscoelastic robustness, and additional electrochemical stability of the IL crystal ionogels provide promising opportunities for future electrochemical applications.

Environmental Molecular Sciences Laboratory↗
DOE OSTI2019

Cross-Linked Nanocellulosic Materials and Their Applications

Nanocelluloses (NCs) have remarkable mechanical properties and contain abundant surface functional groups that can be modified or cross-linked with other materials. They have been widely used as an environment-friendly reinforcing agent in polymer composites. However, for applications that are carried out in humid environments or aqueous suspensions, hydrophilicity of NCs lower their mechanical integrity. Hence, cross-linking techniques have been investigated in recent years for preparing NC-based materials that are dimensionally stable under humid or aqueous environments and have better physicochemical properties. This Minireview examines the quickly growing field of cross-linked NC-based materials, which have many benefits including improved aqueous, structural, mechanical, and thermal stability. In addition, the potential application of cross-linked NC-based materials in adsorption of heavy metal is discussed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Reactions of the N-isopropyl-α-chloroketimines with P{sup IV} dithioacids

A primary iminium salt formed in the reaction of P{sup IV} dithioacids with N-isopropyl-α-chloroketimines is transformed into products of nucleophilic substitution of the chlorine atom by dithiophosphorus group (S{sub N} pathway), if the imine carbon atom is bonded to the donor and small-volume methyl group, or undergoes reduction of the CCl bond (C-Cl→C-H) (Red pathway), when it is bonded with the bulky acceptor phenyl group. The same effect of substituents was discovered, when replacing methyl group with phenyl one in the position 2 of N-tert-butyl-2-chloraldimines: S{sub N}: Red ratio is 1: 0 in the case of Me and 1: 9 in the case of Ph. The iminium salts were transformed into new type ketones containing a phosphor functionality.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2019

Short-time polymerization and convolution kinetics in the analysis of the initiation step of isoprene polymerization over neodymium catalyst

The paper considers a convolution model for polymerization of 1,3-dienes in the presence of organometallic catalysts. It is shown that initial steps of polymerization can be represented as a set of shifted parallel reactions of the chain propagation, in which shift value are governed by the kinetics of the initiation step. In this case, polymer accumulation curve is described by an equation containing convolution of functions which allow one to solve an inverse problem of restoring the function of active site accumulation. Based on the example of isoprene polymerization over neodymium catalyst, it was demonstrated that the results of the inverse problem solution are in good agreement with the experimental data on concentration of the active sites. These data were obtained by a method of controlled introduction of inhibitor in short-time polymerization.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Yttria-Stabilized Zirconia Aided Electrochemical Investigation on Ferric Ions in Mixed Molten Calcium and Sodium Chlorides

Electrolytic reduction of dissolved iron oxide to metal iron in molten salts with an inert anode is an alternative short route for steelmaking without CO{sub 2} emissions. A novel and simple integrated yttria-stabilized zirconia (YSZ) cell was constructed from a YSZ tube with a closed end. The YSZ tube played multiple functions, including the container for the molten salts, the solid electrolyte membrane in the O{sup 2−}|YSZ|Pt|O{sub 2} (air) reference electrode (RE), and the solid electrolyte membrane between the working and counter electrodes (WE and CE). Electrochemical behavior of ferric ions (Fe{sup 3+}) that were formed by dissolution of 0.5 wt pct Fe{sub 2}O{sub 3} in the molten CaCl{sub 2}-NaCl eutectic mixture was investigated on a Pt WE at 1273 K by various electrochemical techniques including cyclic voltammetry, linear scan voltammetry, square wave voltammetry, chronopotentiometry, chronoamperometry, and potentiostatic electrolysis. Analysis of the mechanism of electrode reactions was further assisted by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Some electrochemical parameters were obtained, including the number of exchanged electrons and the diffusion coefficient of ferric ions in the mixed molten salts. The results from various electrochemical techniques are in good agreement with each other, and show that the electrochemical reduction of Fe{sup 3+} to Fe in the molten salt mixture could be a single three-electron transfer step and diffusion-controlled reaction that was also possibly reversible. This work may form the foundation for extraction of iron and alloys from molten salts and also provide a stable O{sup 2−}|YSZ|Pt|O{sub 2} (air) RE with wide applicability for investigation on electrochemical properties of other electroactive metal oxides in molten salts.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Formation of Carbon Dioxide Attached Fragment Ions in the Fragmentation of Deprotonated Tolfenpyrad and Tebufenpyrad

The in-source collision-induced dissociation (CID) and MS/MS mass spectra of deprotonated tolfenpyrad and tebufenpyrad both showed an unusual fragment ion at m/z 187, but its fragmentation pattern and structure could not be explained by logical neutral losses. Accurate mass measurement indicated that the mass difference between this fragment ion and the dominant fragment ion at m/z 143 equaled to a carbon dioxide (CO{sub 2}) molecule. The isolation of the fragment ion m/z 143 in the mass analyzer could spontaneously give rise to the ion m/z 187. The Gibbs free energy of carbon dioxide addition to deprotonated pyrazole ion was significantly negative from the computational results. According to these results, we derived a proposal for the formation and structure of the ion m/z 187, which was an attachment of molecular carbon dioxide to the fragment ion m/z 143 to produce a carboxylate anion. The trace carbon dioxide was speculated to be derived from the residual atmosphere or collision gas in the instrument. This study is valuable for the qualitative and quantitative mass spectrometry analysis of pesticides containing the pyrazole functional group. .

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2015

A new class of asymptotically non-chaotic vacuum singularities

The BKL conjecture, stated in the 1960s and early 1970s by Belinski, Khalatnikov and Lifschitz, proposes a detailed description of the generic asymptotic dynamics of spacetimes as they approach a spacelike singularity. It predicts complicated chaotic behaviour in the generic case, but simpler non-chaotic one in cases with symmetry assumptions or certain kinds of matter fields. Here we construct a new class of four-dimensional vacuum spacetimes containing spacelike singularities which show non-chaotic behaviour. In contrast with previous constructions, no symmetry assumptions are made. Rather, the metric is decomposed in Iwasawa variables and conditions on the asymptotic evolution of some of them are imposed. The constructed solutions contain five free functions of all space coordinates, two of which are constrained by inequalities. We investigate continuous and discrete isometries and compare the solutions to previous constructions. Finally, we give the asymptotic behaviour of the metric components and curvature.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2019

Generalized logarithmic equation of state in classical and loop quantum cosmology dark energy–dark matter coupled systems

In this paper we shall study the phase space of a coupled dark energy–dark matter fluids system, in which the dark energy has a generalized logarithmic corrected equation of state. Particularly, the equation of state for the dark energy will contain a logarithmic function of the dark energy density ρ{sub d} and will also have quadratic and Chaplygin gas-like terms, expressed in terms of ρ{sub d}. We shall use the dynamical system approach in order to study the cosmological dynamics, and by appropriately choosing the dynamical system variables, we shall construct an autonomous dynamical system. The study will be performed in the context of classical and loop quantum cosmology, and the focus is on finding stable de Sitter attractors. As we demonstrate, in both the classical and loop quantum cosmology cases, there exist stable de Sitter attractors in the phase space, with the loop quantum cosmology case though having a wider range of the free parameter values for which the stable de Sitter attractors may occur. It is emphasized that the use of a generalized dark energy equation of state makes possible the existence of de Sitter attractors, which were absent in the case that a simple logarithmic term constitutes the dark energy equation of state.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗