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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,009 records · Page 56
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

The effect of concentration on the structure and crystallinity of a cementitious waste form for caustic wastes

Cement-based waste forms have long been considered economical technologies for disposal of various types of waste. A solidified cementitious waste form, Cast Stone, was developed to immobilize the radioactive secondary waste from vitrification processes. In this work, Cast Stone was considered for a Na-based caustic liquid waste, and its physical properties were analyzed as a function of liquid waste loading up to 2 M Na. Differences in crystallinity (phase composition), microstructure, mesostructure (pore size distribution, surface area), and macrostructure (density, compressive strength) were investigated using various analytical techniques, in order to assess the suitability of Cast Stone as a chemically durable waste. It was found that the concentration of secondary waste simulant (caustic waste) had little effect on the relevant engineering properties of Cast Stone, showing that Cast Stone could be an effective and tolerant waste form for a wide range of concentrations of high sodium waste.

Cast Stone↗
DOE OSTI2021

Morphological and chemical characteristics of oxide scales formed on δ-Phase plutonium metal alloys I: 3.5 at% ga

Focused ion-beam scanning electron microscopy (FIB-SEM) and three-dimensional (3D) microscopy were applied to characterize the subsurface morphological features of oxide scales formed on an ~3.5 at.% Ga plutonium (Pu) metal alloy. Using the FIB-SEM technique, a number of morphological features formed in the interior of the oxide scale from Pu metal's environmental exposure were observed and identified. Here, Auger electron spectroscopy (AES) was utilized to characterize the cross-sectional composition and chemistry of the oxide scale. The oxide scale formed during inert storage and operational environments has a characteristic internal scale structure that includes a relatively dense oxide layer with some lateral and transverse cracking. Generally, after subsequent exposure to dry air environment, the oxide scale retained most of the original structural and chemical characteristics. However, after aging in a moist air environment, while the oxide scale was found to maintain the chemical characteristics of the source oxide, the scale was found to be on average thinner and without the previously observed internal microcracking, likely the result of spallation of the source scale during exposure to the new environment.

36 MATERIALS SCIENCE↗
DOE OSTI2017

New crystal forms of the integral membrane Escherichia coli quinol:fumarate reductase suggest that ligands control domain movement

Quinol:fumarate reductase (QFR) is an integral membrane protein and a member of the respiratory Complex II superfamily. Although the structure of Escherichia coli QFR was first reported almost twenty years ago, many open questions of catalysis remain. Here we report two new crystal forms of QFR, one grown from the lipidic cubic phase and one grown from dodecyl maltoside micelles. QFR crystals grown from the lipid cubic phase processed as P1, merged to 7.5 Å resolution, and exhibited crystal packing similar to previous crystal forms. Crystals grown from dodecyl maltoside micelles processed as P21, merged to 3.35 Å resolution, and displayed a unique crystal packing. Furthermore, this latter crystal form provides the first view of the E. coli QFR active site without a dicarboxylate ligand. Instead, an unidentified anion binds at a shifted position. In one of the molecules in the asymmetric unit, this is accompanied by rotation of the capping domain of the catalytic subunit. In the other molecule, this is associated with loss of interpretable electron density for this same capping domain. Analysis of the structure suggests that the ligand adjusts the position of the capping domain.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2011

Chemical and structural analyses of subsurface crevices formed during spontaneous deposition of cerium-based conversion coatings

Subsurface crevices formed during the deposition of cerium-based conversion coatings were analyzed in cross-section to assess the effect of deposition and post-treatment on the structure and chemistry of phases present. An Al-O containing phase, believed to be amorphous Al(OH){sub 3}, was formed in crevices during coating deposition. Analysis by energy dispersive X-ray spectroscopy revealed the presence of up to 1.6 at.% chlorine within the Al-O phase, which was likely a product of soluble chlorides that were present in the coating solution. Cerium was not detected within crevices. After post-treatment in an 85 deg. C aqueous phosphate solution, the chloride concentration was reduced to {<=} 0.30 at.% and electron diffraction of the Al-O phase produced ring patterns, indicating it had crystallized. Some diffraction patterns could be indexed to gibbsite (Al(OH){sub 3}), but others are believed to be a combination of hydrated aluminum hydroxides and/or oxides. Aluminum phosphate was not identified. Separately from its effect on cerium-based conversion coatings, phosphate post-treatment improved the corrosion resistance of Al 2024-T3 substrates by acting to crystallize Al(OH){sub 3} present on interior surfaces of crevices and by reducing the chloride concentration in this phase. - Highlights: {yields} Analysis of subsurface crevices formed during deposition of Ce-based conversion coatings. {yields} Phosphate post-treatment improved corrosion protection in salt spray testing. {yields} Post-treatment affected the composition and structure of regions within crevices. {yields} Crystallized Al(OH){sub 3} within crevices acted as a more effective barrier to chloride ions.

36 MATERIALS SCIENCE↗
DOE OSTI2018

A novel interface strengthening layer: Nanoscale AuCu super-structure formed during Au80Sn20/Cu rapid solidification soldering process

Highlights: • The nanoscale AuCu super-structure formed in Au80Sn20/Cu soldering joint. • The phase-transformation diffusion mechanism of Au80Sn20/Cu soldering process was studied. • The orientation relationship of Au80Sn20/Cu intermetallic compounds was investigated. • The interfacial strengthening mechanism of nanoscale AuCu layer was discussed. - Abstract: Phase composition and orientation of intermetallic compounds layers determine the functional and mechanical properties of solder joints. In this paper, interfacial reaction and strengthening mechanism of Au80Sn20/Cu joint by rapid solidification reflow soldering were studied. The Au80Sn20/Cu solder joint by rapid solidification reflow soldering exhibit a superior shear property, and the shear strength reaches up to 90 MPa. It is found that a new nanoscale AuCu super-structure formed in the interfacial intermetallic compounds layer, which is coherent with the [001] Cu substrate. The orientation relationship of Cu matrix/interfacial intermetallic compounds is determined to be [001]{sub Cu}∥[001]{sub AuCu}∥[ 2-bar 4 2-bar 3]{sub (AuCu){sub 5Sn}} and (200){sub Cu}∥(200){sub AuCu}∥(10 1-bar 0){sub (AuCu){sub 5Sn}}. Nanoscale AuCu super-structure influences the interface slip direction and provides interface misfit dislocation, hinder the dislocation movement, lead to the interface strengthening effect. Our finding on nanoscale AuCu super-structure formed during Au80Sn20/Cu soldering process not only sheds light on future research direction but also provides practical guidance to the engineers in solder industry.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Characterization of hot extrusion and heat treatment on mechanical properties in a spray formed ultra-high strength Al-Zn-Mg-Cu alloy

Highlights: • The spray forming technology was used to fabricate ultra-high strength aluminum alloy. • The alloy under RRA state obtained the highest ultimate tensile strength of 732 MPa. • The effects of dislocations, solutes and precipitates etc., on yield strength were calculated. • Precipitation was characterized as the main strengthening mechanism for aging states. - Abstract: To obtain the optimal mechanical properties, several processes including spray forming technology, two passes hot extrusion and substantial heating treatments were operated on an Al-Zn-Mg-Cu-Zr alloy. The characterization methods used in this study include tensile tests, X-ray diffraction, differential scanning calorimetry and microstructure observations by optical microscope, scanning and transmission electron microscopy. The typical characteristics were the refined grain, homogeneous precipitates and porosity in the as-deposited pre-forms. The ultimate tensile strength, yield strength, hardness and elongation improved significantly after two passes hot extrusion. A good combination of ultimate tensile strength at 704 MPa and elongation at 9.7% were achieved under peak-aged treatment. The best ultimate tensile strength was obtained at 732 MPa after re-aging and regression. It was main dimple fracture in the extruded and aging treated specimens while brittle fracture for the as-deposited. The secondary phases were main MgZn{sub 2} and Al{sub 3}Zr dispersoids throughout all the states. The contributions of grain boundaries, dislocations, solid-solution and precipitates on the yield strength were analyzed using a quantitative equation.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Impact of carbonation on leaching of constituents from a cementitious waste form for treatment of low activity waste at the DOE Hanford site

Carbonation can be a major aging process during disposal of alkaline cementitious waste forms and can impact constituent leaching by changes in material alkalinity, pore structure, and controlling mineral phases. The effect of carbonation on the leaching of major and trace constituents from Cast Stone, a cementitious waste form developed to treat high salt content low activity waste, was studied through a combination of leaching experiments and reactive transport simulations. Diffusive transport of constituents in the waste form was evaluated using reactive transport modeling of diffusion-controlled leaching test results and a geochemical speciation model derived from pH-dependent leaching. Comparisons between Cast Stone materials aged under nitrogen, air, and 2% carbon dioxide in nitrogen showed that carbonation impacts solubility, physical retention and observed diffusivity of major and trace constituents. Carbonation under 2% CO 2 decreased the diffusion-controlled leaching of chromium by two orders of magnitude. Finally, modeling results suggest that carbonation may also decrease solubility of technetium while changes to microstructure by carbonation increases effective diffusivity of constituents in Cast Stone.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

MIER3 induces epithelial-mesenchymal transition and promotes breast cancer cell aggressiveness via forming a co-repressor complex with HDAC1/HDAC2/Snail

Highlights: • The expression of MIER3 was correlated with poor outcome of breast cancer patients. • MIER3 induced EMT and promoted cell migration. • MIER3 interacted with HDAC1/HDAC2 and Snail to form a repressive complex. • The repressive complex bound to E-cadherin promoter and reduced its acetylation. Breast cancer is one of the most frequently diagnosed cancers and the leading cause of cancer death in women. MIER3 (Mesoderm induction early response 1, family member3) is considered as a potential oncogene for breast cancer. However, the role of MIER3 in breast cancer remain largely unknown. The expression of MIER3 was detected and the relationship between its expression and clinicopathological characteristics was also analyzed. The effect of MIER3 on proliferation and migration of breast cancer cells was detected in vitro and in vivo. Western blot, IF, and Co-IP were employed to detect the relationship between MIER3, HDAC1, HDAC2, and Snail. ChIP assay was performed to determine the binding of MIER3/HDAC1/HDAC2/Snail complex to the promoter of E-cadherin. In this study, we found that MIER3 was upregulated in breast cancer tissue and closely associated with poor prognosis of patients. MIER3 could promote the proliferation, migration, and epithelial-mesenchymal transition (EMT) of breast cancer cells. Further studies showed that MIER3 interacted with HDAC1/HDAC2 and Snail to form a repressive complex which could bind to E-cadherin promoter and was related to its deacetylation. Our study concluded that MIER3 was involved in forming a co-repressor complex with HDAC1/HDAC2/Snail to promote EMT by silencing E-cadherin.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Non-Gaussianity of optical emission lines in SDSS star-forming galaxies and its implications on galactic outflows

The shape of emission lines in the optical spectra of star-forming galaxies reveals the kinematics of the diffuse gaseous component. We analyse the shape of prominent emission lines in a sample of ~ 53000 star-forming galaxies from the Sloan Digital Sky Survey, focusing on departures from gaussianity. Departures from a single gaussian profile allow us to probe the motion of gas and to assess the role of outflows. The sample is divided into groups according to their stellar velocity dispersion and star formation rate (SFR). The spectra within each group are stacked to improve the signal-to-noise ratio of the emission lines, to remove individual signatures, and to enhance the effect of SFR on the shapes of the emission lines. The moments of the emission lines, including kurtosis and skewness, are determined. We find that most of the emission lines in strong star-forming systems unequivocally feature negative kurtosis. This signature is present in Hβ, Hα, [N ii], and [S ii] in massive galaxies with high SFRs. We attribute it as evidence of radial outflows of ionised gas driven by the star formation of the galaxies. Also, most of the emission lines in low-mass systems with high SFRs feature negative skewness, and we interpret it as evidence of dust obscuration in the galactic disk. These signatures are however absent in the [O iii] line, which is believed to trace a different gas component. The observed trend is significantly stronger in face-on galaxies, indicating that star formation drives the outflows along the galactic rotation axis, presumably the path of least resistance. The data suggest that outflows driven by star formation exert accumulated impacts on the interstellar medium, and the outflow signature is more evident in older galaxies as they have experienced a longer total duration of star formation.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2024

Electrochemically-Formed Disordered Rock Salt ω-Li x V 9 Mo 6 O 40 as a Fast-Charging Li-Ion Electrode Material

Electrochemically-formed disordered rock salt compounds are an emerging class of Li-ion electrode materials for fast-charging energy storage. However, the specific factors that govern the formation process and the resulting charge storage performance are not well understood. Here, we characterize the transformation mechanism and charge storage properties of an electrochemically-formed disordered rock salt from V 9 Mo 6 O 40 (VMO). The crystal structure of VMO has similar motifs to that of α-V 2 O 5 , a well-studied analogue, but VMO has less mechanical flexibility due to additional corner-sharing octahedra in its structure. As a result, VMO undergoes a single-step transformation pathway, which we characterize through operando X-ray diffraction, and forms an unusual highly distorted lamellar microstructure, as we show with high-resolution transmission electron microscopy. The resulting Li x VMO material shows fast charging and other electrochemical characteristics and performance typical of many nanomaterials, even though the material is composed of relatively large particles.

25 ENERGY STORAGE↗
DOE OSTI2016

Mass Spectrometric Characterization of an Acid-Labile Adduct Formed with 2-Amino-1-methyl-6-phenylimidazo[4,5- b ]pyridine and Albumin in Humans

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a carcinogenic heterocyclic aromatic amine formed during the high-temperature cooking of meats. The cytochrome P450-mediated N-hydroxylation of the exocyclic amine group of PhIP produces 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-$b$]pyridine, an electrophilic metabolite that forms adducts with DNA and proteins. Previous studies conducted by our laboratory showed that the reaction of N-oxidized PhIP metabolites with human albumin in vitro primarily occurs at the Cys 34 residue, to produce an acid-labile linked sulfinamide adduct. On the basis of these findings, we developed a sensitive ultraperformance liquid chromatography–mass spectrometry method to measure acid-labile albumin–PhIP adducts in human volunteers administered a dietary-relevant dose of 14 C-labeled PhIP [Dingley, K. H., et al. (1999) Cancer Epidemiol., Biomarkers Prev. 8, 507–512]. Mild acid treatment of albumin (0.1 N HCl, 37 °C for 1 h) or proteolytic digestion with Pronase [50 mM ammonium bicarbonate buffer (pH 8.5) at 37 °C for 18 h] released similar amounts of covalently bound PhIP, which was characterized by multistage scanning and quantified by Orbitrap mass spectrometry. The amount of [ 14 C]PhIP recovered by acid treatment of albumin 24 h following dosing accounted for 7.2–21.3% of the [ 14 C]PhIP bound to albumin based on accelerator mass spectrometry measurements. 2-Amino-1-methyl-6-(5-hydroxy)phenylimidazo[4,5-b]pyridine, a hydrolysis product of the Cys 34 S–N linked sulfenamide adduct of PhIP, was not detected in either acid-treated or protease-treated samples. These findings suggest that a portion of the PhIP bound to albumin in vivo probably occurs as an acid-labile sulfinamide adduct formed at the Cys 34 residue.

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

Mechanism and Energetics of the Hydrolysis of Th + To Form Th(OD) 3 + : Guided Ion Beam and Theoretical Studies of ThO + , ThO 2 + , and OThOD + Reacting with D 2 O

The kinetic energy dependences of the reactions of ThO + , ThO 2 + , and OThOD + with D 2 O, ThO 2 + with D 2 , and OThOD + with Xe were studied using guided ion beam tandem mass spectrometry. Exothermic formation of OThOD + is the dominant process observed in reactions of both ThO + and ThO 2 + with D 2 O. Minor products formed in endothermic reactions include ThO 2 + , DThO + , and ThO 2 D 2 + . OThOD + is also formed in the reaction of ThO 2 + with D 2 but in an endothermic process. Collision-induced dissociation of OThOD + with Xe leads to endothermic loss of the hydroxide ligand. OThOD + reacts further with D 2 O to form the associative complex ThO 3 D 3 + , which is long-lived before dissociating back to the reactants. The OThOD + D 2 O bond energy of the associative complex is measured to be 2.96 ± 0.05 eV by modeling the kinetic energy dependent cross section for association using a phase space theory (PST) model that rigorously conserves angular momentum. By comparison with theory, this bond energy identifies the ThO 3 D 3 + species as the trihydroxide cation, Th(OD) 3 + . From the endothermic reactions and CID of OThOD + with Xe, the OTh + -D, OTh + -O, and OTh + -OD bond dissociation energies are measured to be 2.33 ± 0.24, 4.66 ± 0.15, and 6.00 ± 0.17 eV, respectively. All four of these BDEs are experimentally determined for the first time and agree reasonably well with values calculated at the B3LYP, B3PW91, and PBE0 levels of theory with cc-pVQZ basis sets. Complete potential energy surfaces for all reactions were calculated at the B3LYP/cc-pVTZ level and elucidate the mechanisms for all processes observed.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Unraveling the Heterogeneous but Ordered Microstructure of the Nonionic Deep Eutectic Solvent Formed by Lauric Acid and N -Methylacetamide

The nonionic deep eutectic solvent, formed by lauric acid (LA) and N-methylacetamide (NMA), has been shown to have a heterogeneous molecular structure in which the LA and NMA form nonpolar and polar domains, respectively. Previous vibrational spectroscopy experiments demonstrated that the ability of the LA domains to solvate compounds was limited to long carbon chains, whereas other nonpolar molecules, such as W(CO) 6 , were found to be solvated by both LA and NMA. These experiments were not fully compatible with the previously proposed micelle-like structure of the nonpolar domains of the LA-NMA DES. In this work, the modeling of the DES molecular structure is pursued using classical molecular dynamics simulations. The new classical model reproduces both the SAXS structural factors and the previously experimentally derived interaction map for these LA-NMA DESs. In addition, the simulation also shows that LA-NMA DESs form highly organized LA aggregates that are difficult to disorganize. Further evidence of the correct description provided by the newly derived model is obtained using a moderately polar probe: chloroform-d. Computations using the classical model have a good agreement with the solvation behavior of the probe derived from experiments, in which the location of the probe is found to be mostly within the polar domain of the DES. The computational model also demonstrates that the probe solvation is a consequence of the tightly packed LA structure, which causes nonpolar molecules to be located at the interphase of the DES nonpolar domains.

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

Multicomponent and Multiphase Lipid Nanotubes Formed by Gliding Microtubule-Kinesin Motility and Phase-Separated Giant Unilamellar Vesicles

Cytoskeletal filaments and motor proteins are critical components in the transport and reorganization of membrane-based organelles in eukaryotic cells. Previous studies have recapitulated the microtubule-kinesin transport system in vitro to dynamically assemble large-scale nanotube networks from multilamellar liposomes and polymersomes. Moving toward more biologically relevant systems, this work examines whether lipid nanotube (LNT) networks can be generated from giant unilamellar vesicles (GUVs) and subsequently characterizes how the lipid composition may be tuned to alter the dynamics, structure, and fluidity of networks. Here, we describe a two-step process in which microtubule motility (i) drives the transport and aggregation of GUVs to form structures with a decreased energy barrier for LNT formation and (ii) extrudes LNTs without destroying parent GUVs, allowing for the formation of large LNT networks. We further show that the lipid composition of the GUV influences formation and morphology of the extruded LNTs and associated networks. For example, LNTs formed from phase-separated GUVs (e.g., liquid–solid phase-separated and coexisting liquid-ordered and liquid-disordered phase-separated) display morphologies related to the specific phase behavior reflective of the parent GUVs. Overall, the ability to form nanotubes from compositionally complex vesicles opens the door to generating lipid networks that more closely mimic the structure and function of those found in cellular systems.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2019

Reconfigurable Multicompartment Emulsion Drops Formed by Nematic Liquid Crystals and Immiscible Perfluorocarbon Oils

Liquid crystalline (LC) oils provide the basis of stimuli-responsive LC-in-water emulsions. Although past studies have explored the properties of single-phase LC emulsions, few studies have focused on complex multicompartment emulsions containing co-existing isotropic and LC domains. In this paper, we report a study of multiphase emulsions using LCs and immiscible perfluoroalkanes dispersed in water or glycerol (the latter continuous phase is used to enable characterization). We found that the nematogen 4'-pentyl-4-biphenylcarbonitrile (5CB) anchors homeotropically (perpendicularly) and weakly at liquid perfluorononane (F9) interfaces, consistent with the smectic layering of 5CB molecules. The proposed role of smectic layering is supported by experiments performed with 4-(trans-4-pentylcyclohexyl)benzonitrile, a nematogen that possesses a cyclohexyl group that frustrates the smectic packing and leads to tilted orientations at the F9 interface. By employing perfluorocarbon and hydrocarbon surfactants in combination with multiphase 5CB and F9 emulsion droplets dispersed in a continuous water or glycerol phase, we observe a range of emulsion droplet morphologies to form, including core–shell and Janus structures, with internal organizations that reflect an interplay of interfacial (anchoring energies; F9 and glycerol) and elastic energies within the confines of the geometry of the emulsion droplet. By comparing experimental observations to simulations of the LC–perfluorocarbon droplets based on a Landau-de Gennes model of the free energy, we place bounds on the orientation-dependent interfacial energies that underlie the internal ordering of these complex emulsions. Additionally, by forming core–shells emulsion droplets from 5CB (shell) and perfluoroheptane (cores), we demonstrate how a liquid-to-vapor phase transition in the perfluorocarbon core can be used to actuate the droplet and rapidly thin the nematic shell. Overall, the findingss reported in this paper demonstrate that multiphase LC emulsions formed from mixtures of perfluoroalkanes and LCs provide new opportunities to engineer hierarchical and stimuli-responsive emulsion systems.

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

Reversible 1,2-Addition of Water To Form a Nucleophilic Mn(I) Hydroxide Complex: A Thermodynamic and Reactivity Study

( iPr PN H P)Mn(CO) 2 (OH) (2; iPr PN H P = HN{CH 2 CH 2 (P i Pr 2 )} 2 ) was formed from the reversible 1,2-addition of water to ( iPr PNP)Mn(CO) 2 (1; iPr PNP = the deprotonated, amide form of the ligand, –N{CH 2 CH 2 (P i Pr 2 )} 2 ). This reversible reaction was probed via variable-temperature NMR experiments, and the energetics of the 1,2-addition/elimination was found to be slightly exothermic (-0.8 kcal/mol). The corresponding manganese hydroxide was found to react with aldehydes, yielding the corresponding manganese carboxylate complexes ( iPr PN H P)Mn(CO) 2 (CO 2 R), where R = H, methyl, phenyl. While no reaction between 1 and neat benzaldehyde was observed, in the presence of water, conversion to the corresponding manganese-bound benzoate with formation of H 2 was observed. The catalytic oxidation of benzaldehyde by water without additives was unsuccessful due to strong product inhibition, with the manganese benzoate formed under a variety of reaction conditions. Upon addition of base, a catalytic cycle for the conversion of aldehyde to carboxylate and hydrogen can be devised.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

The Roles of Oil–Water Interfaces in Forming Ultrasmall CaSO 4 Nanoparticles

In natural and engineered environmental systems, calcium sulfate (CaSO 4 ) nucleation commonly occurs at dynamic liquid–liquid interfaces. Although CaSO 4 is one of the most common minerals in oil spills and oil–water separation, the mechanisms driving its nucleation at these liquid–liquid interfaces remain poorly understood. Here, in this study, using in situ small-angle X-ray scattering (SAXS), we examined CaSO 4 nucleation at oil–water interfaces and found that within 60 minutes of reaction, short rod-shaped nanoparticles (with a radius of gyration (R g ) of 17.2 ± 2.7 nm and a length of 38.2 ± 5.8 nm) had formed preferentially at the interfaces. Wide-angle X-ray scattering (WAXS) analysis identified these nanoparticles as gypsum (CaSO 4 ·2H 2 O). In addition, spherial nanoparticles measuring 4.1 nm in diameter were observed at oil–water interfaces, where surface-enhanced Raman spectroscopy (SERS) revealed an elevated pH compared to the bulk solution. The negatively charged oil–water interfaces preferentially adsorb calcium ions, collectively promoting CaSO 4 formation there. CaSO 4 particle formation at the oil–water interface follows a nonclassical nucleation (N-CNT) pathway by forming ultrasmall amorphous spherical particles which then aggregate to form intermediate nanoparticles, subsequently growing into nanorod-shaped gypsum. These findings of this study provide insights into mineral scaling during membrane separation and can inform more efficient oil transport in energy recovery systems.

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

Inorganic Sulfur Species Formed upon Heterogeneous OH Oxidation of Organosulfates: A Case Study of Methyl Sulfate

In this report recent studies reveal that organosulfates at the particle surface can be oxidized by gas-phase OH radicals with significant rates. Inorganic sulfur species, such as the bisulfate ion (HSO 4 - ) and sulfate ion (SO 4 2- ), can be formed upon these heterogeneous oxidation processes through the formation and subsequent reactions of sulfate radical anions (SO 4 •- ) in the particle phase. However, the amount of inorganic sulfur species produced in these heterogeneous oxidation reactions is not known. We investigate the heterogeneous OH oxidation of sodium methyl sulfate (CH 3 SO 4 Na), the smallest organosulfate detected in atmospheric particles, using an oxidation flow reactor at a relative humidity of 75%. We quantify the kinetics by measuring the decay of CH 3 SO 4 Na and the amount of HSO 4 - and SO 4 2- formed upon oxidation using ion chromatography. Kinetic measurements determine the heterogeneous OH reaction rate to be (5.72 ± 0.14) x 10 -13 cm 3 molecule -1 s -1 , with an effective OH uptake coefficient, γ eff , of 0.31 ± 0.06. The molar yield of inorganic sulfur species, defined as the total number of moles of HSO 4 - and SO 4 2- formed per mole of CH 3 SO 4 Na consumed upon oxidation, is found to be significant and has an average value of 0.62 ± 0.18 upon oxidation. A kinetic model is developed to describe the kinetics and inorganic sulfur species formation upon oxidation. Model simulations suggest that CH 3 SO 4 Na tends to decompose rapidly into formaldehyde and SO 4 •- , and the reaction of SO 4 •- with CH 3 SO 4 Na plays a significant role in both governing the kinetics and the formation of inorganic sulfur species.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗