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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Nd(Sb3Os)4 by Materials Project

NdOs4Sb12 is Skutterudite-derived structured and crystallizes in the cubic Im-3 space group. The structure is three-dimensional and consists of two neodymium molecules and one OsSb3 framework. In the OsSb3 framework, Os+0.75- is bonded to six equivalent Sb atoms to form corner-sharing OsSb6 octahedra. The corner-sharing octahedral tilt angles are 55°. All Os–Sb bond lengths are 2.65 Å. Sb is bonded in a 2-coordinate geometry to two equivalent Os+0.75- and two equivalent Sb atoms. There are one shorter (2.95 Å) and one longer (3.04 Å) Sb–Sb bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Pr(Sb3Os)4 by Materials Project

PrOs4Sb12 is Skutterudite-derived structured and crystallizes in the cubic Im-3 space group. The structure is three-dimensional and consists of two praseodymium molecules and one OsSb3 framework. In the OsSb3 framework, Os+0.75- is bonded to six equivalent Sb atoms to form corner-sharing OsSb6 octahedra. The corner-sharing octahedral tilt angles are 55°. All Os–Sb bond lengths are 2.65 Å. Sb is bonded in a 2-coordinate geometry to two equivalent Os+0.75- and two equivalent Sb atoms. There are one shorter (2.96 Å) and one longer (3.02 Å) Sb–Sb bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sm(Sb3Os)4 by Materials Project

SmOs4Sb12 is Skutterudite-derived structured and crystallizes in the cubic Im-3 space group. The structure is three-dimensional and consists of two samario molecules and one OsSb3 framework. In the OsSb3 framework, Os+0.75- is bonded to six equivalent Sb atoms to form corner-sharing OsSb6 octahedra. The corner-sharing octahedral tilt angles are 54°. All Os–Sb bond lengths are 2.65 Å. Sb is bonded in a 2-coordinate geometry to two equivalent Os+0.75- and two equivalent Sb atoms. There are one shorter (2.95 Å) and one longer (3.05 Å) Sb–Sb bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ce(Sb3Os)4 by Materials Project

CeOs4Sb12 is Skutterudite-derived structured and crystallizes in the cubic Im-3 space group. The structure is three-dimensional and consists of two cerium molecules and one OsSb3 framework. In the OsSb3 framework, Os+0.75- is bonded to six equivalent Sb atoms to form corner-sharing OsSb6 octahedra. The corner-sharing octahedral tilt angles are 54°. All Os–Sb bond lengths are 2.64 Å. Sb is bonded in a 2-coordinate geometry to two equivalent Os+0.75- and two equivalent Sb atoms. There are one shorter (2.95 Å) and one longer (3.05 Å) Sb–Sb bond lengths.

36 MATERIALS SCIENCE↗
NASA NTRS1992

Ultraviolet studies of Novae in the Large Magellanic Cloud

We report on the ultraviolet observations of five novae in the Large Magellanic Cloud (LMC). They are LMC 1988 #1, which was a CO nove similar to OS And; LMC 1988 #2, which was an ONeMg nova similar to Nova Her 1991; LNC 1990 #1, which was a very fast ONeMG nova similar to V693 CrA 1981; LMC 1990 #2, which was a recurrent nova similar to U Sco; and LMC 1991 which reached V approximately 9.

Starrfield, Sumner↗
DOE OSTI2020

Metabolites of Tobacco- and E-Cigarette-Related Nitrosamines Can Drive Cu 2+ -Mediated DNA Oxidation

Nitrosamine metabolites resulting from cigarette smoking and E-cigarette (E-cig) vaping cause DNA damage that can lead to genotoxicity. While DNA adducts of metabolites of nitrosamines 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and N-nitrosonornicotine (NNN) are well-known tobacco-related cancer biomarkers, only a few studies implicate NNN and NNK in DNA oxidation in humans. NNK and NNN were found in the urine of E-cigarette users who never smoked cigarettes. This paper proposes the first chemical pathways of DNA oxidation driven by NNK and NNN metabolites in redox reactions with Cu 2+ and NADPH leading to reactive oxygen species (ROS). A microfluidic array with thin films of DNA and metabolic enzymes that make metabolites of NNN and NNK in the presence of Cu 2+ and NADPH was used to estimate relative rates of DNA oxidation. Detection by electrochemiluminescence (ECL) employed a new ECL dye [Os(tpy-benz-COOH) 2 ] 2+ that is selective for and sensitive to the primary DNA oxidation product 8-oxo-7,8-dihydro-2-deoxyguanosine (8-oxodG) in DNA. Enzyme–DNA films on magnetic beads were used to produce nitrosamine metabolites that enter ROS-forming redox cycles with Cu 2+ and NADPH, and liquid chromatography–mass spectrometry (LC–MS) was used to quantify 8-oxodG and identify metabolites. ROS were detected by optical sensors. Metabolites of NNK and NNN + Cu 2+ + NADPH generated relatively high rates of DNA oxidation. Lung is the exposure route in smoking and vaping, human lung tissue contains Cu 2+ and NADPH, and lung microsomal enzymes gave the highest rates of DNA oxidation in this study. Furthermore, E-cigarette vapor contains 6-fold more copper than that in cigarette smoke, which could exacerbate DNA oxidation.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2023

Exceptional high temperature retention in Al 0.93 B 0.07 N films

This paper reports the retention behavior for Al 0.93 B 0.07 N thin films, a member of the novel family of wurtzite ferroelectrics. Our experiments suggest that bipolar cycling of metal (Pt/W)/Al 0.93 B 0.07 N/W/Al 2 O 3 film stacks first induced wake-up and then a region of constant switchable polarization. Here, the films showed excellent retention of the stored polarization state. As expected, data retention was slightly inferior in the opposite state (OS) measurements. However, it is noted that even after 3.6 × 10 6 s (1000 h) at 200 °C, the OS signal margin still exceeded 200 μC/cm 2 . The predicted OS retention is 82% after 10 yr baking at 200 °C.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Strongly anisotropic electronic and magnetic structures in oxide dichlorides RuOCl 2 and OsOCl 2

The van der Waals oxide dichlorides MOX 2 (M=V, Ta, Nb, Ru, and Os; X=halogen element), with different electronic densities, are attracting considerable attention. Ferroelectricity, spin-singlet formation, and orbital-selective Peierls phases were reported in this family with d 1 or d 2 electronic configurations, all believed to be caused by the strongly anisotropic electronic orbital degree of freedom. Here, using density functional theory and density matrix renormalization group methods, we investigate the electronic and magnetic properties of RuOCl 2 and OsOCl 2 with d 4 electronic configurations. Different from a previous study using VOI 2 with d 1 configuration, these systems with 4d4 or 5d4 do not exhibit a ferroelectric instability along the a axis. Due to the fully occupied dxy orbital in RuOCl 2 and OsOCl 2 , the Peierls instability distortion disappears along the b axis, leading to an undistorted Immm phase (No. 71). Furthermore, we observe strongly anisotropic electronic and magnetic structures along the a axis. For this reason, the materials of our focus can be regarded as “effective one-dimensional” systems even when they apparently have a dominant two-dimensional lattice geometry. The large crystal-field splitting energy (between dxz/yz and dxy orbitals) and large hopping between nearest-neighbor Ru and Os atoms suppresses the J = 0 singlet state in MOCl 2 (M=Ru or Os) with electronic density n = 4, resulting in a spin-1 system. Moreover, we find staggered antiferromagnetic order with π wave vector along the M-O chain direction (a axis) while the magnetic coupling along the b axis is weak. Based on Wannier functions from first-principles calculations, we calculated the relevant hopping amplitudes and crystal-field splitting energies of the t 2g orbitals for the Os atoms to construct a multiorbital Hubbard model for the M-O chains. Staggered AFM with ↑|-|↓-↑|-|↓ spin structure dominates in our density matrix renormalization group calculations, in agreement with density functional theory calculations. Our results for RuOCl 2 and OsOCl 2 provide guidance to experimentalists and theorists working on this interesting family of oxide dichlorides.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2020

Materials Data on Sc44Os7 by Materials Project

Sc44Os7 crystallizes in the cubic F-43m space group. The structure is three-dimensional. there are eleven inequivalent Sc sites. In the first Sc site, Sc is bonded in a 1-coordinate geometry to one Sc and two Os atoms. The Sc–Sc bond length is 3.17 Å. There are one shorter (2.81 Å) and one longer (3.14 Å) Sc–Os bond lengths. In the second Sc site, Sc is bonded in a 3-coordinate geometry to three equivalent Sc and three equivalent Os atoms. All Sc–Sc bond lengths are 3.34 Å. All Sc–Os bond lengths are 2.96 Å. In the third Sc site, Sc is bonded in a 1-coordinate geometry to two equivalent Sc and two Os atoms. Both Sc–Sc bond lengths are 3.13 Å. There are one shorter (2.68 Å) and one longer (3.13 Å) Sc–Os bond lengths. In the fourth Sc site, Sc is bonded in a distorted linear geometry to two equivalent Os atoms. Both Sc–Os bond lengths are 2.93 Å. In the fifth Sc site, Sc is bonded in a trigonal planar geometry to three equivalent Sc and three equivalent Os atoms. All Sc–Sc bond lengths are 3.04 Å. All Sc–Os bond lengths are 2.72 Å. In the sixth Sc site, Sc is bonded in a 2-coordinate geometry to four Sc and two Os atoms. There are two shorter (3.30 Å) and two longer (3.41 Å) Sc–Sc bond lengths. There are one shorter (3.01 Å) and one longer (3.15 Å) Sc–Os bond lengths. In the seventh Sc site, Sc is bonded in a 12-coordinate geometry to twelve Sc and two equivalent Os atoms. There are a spread of Sc–Sc bond distances ranging from 3.28–3.71 Å. Both Sc–Os bond lengths are 3.42 Å. In the eighth Sc site, Sc is bonded to twelve Sc atoms to form ScSc12 cuboctahedra that share edges with three equivalent OsSc12 cuboctahedra and faces with three equivalent ScSc12 cuboctahedra. There are six shorter (3.24 Å) and three longer (3.49 Å) Sc–Sc bond lengths. In the ninth Sc site, Sc is bonded in a distorted trigonal non-coplanar geometry to three equivalent Sc and three equivalent Os atoms. All Sc–Sc bond lengths are 3.22 Å. All Sc–Os bond lengths are 2.95 Å. In the tenth Sc site, Sc is bonded in a distorted single-bond geometry to five Sc and one Os atom. The Sc–Sc bond length is 3.48 Å. The Sc–Os bond length is 2.77 Å. In the eleventh Sc site, Sc is bonded in a 2-coordinate geometry to twelve Sc and two equivalent Os atoms. Both Sc–Os bond lengths are 3.27 Å. There are three inequivalent Os sites. In the first Os site, Os is bonded in a 12-coordinate geometry to twelve Sc atoms. In the second Os site, Os is bonded to twelve Sc atoms to form a mixture of face and corner-sharing OsSc12 cuboctahedra. In the third Os site, Os is bonded to twelve Sc atoms to form OsSc12 cuboctahedra that share corners with six OsSc12 cuboctahedra and edges with three equivalent ScSc12 cuboctahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Hf2Os by Materials Project

Hf2Os crystallizes in the cubic Fd-3m space group. The structure is three-dimensional. there are two inequivalent Hf sites. In the first Hf site, Hf is bonded in a 6-coordinate geometry to six equivalent Os atoms. All Hf–Os bond lengths are 2.72 Å. In the second Hf site, Hf is bonded in a 2-coordinate geometry to four equivalent Os atoms. There are two shorter (2.82 Å) and two longer (3.15 Å) Hf–Os bond lengths. Os is bonded in a 9-coordinate geometry to nine Hf atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Tl8Os8O27 by Materials Project

Os8Tl8O27 crystallizes in the tetragonal P-4m2 space group. The structure is three-dimensional. there are two inequivalent Os+5.75+ sites. In the first Os+5.75+ site, Os+5.75+ is bonded to six O2- atoms to form OsO6 octahedra that share corners with six OsO6 octahedra, edges with four equivalent TlO8 hexagonal bipyramids, and edges with two equivalent TlO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 31–46°. There are a spread of Os–O bond distances ranging from 1.91–1.99 Å. In the second Os+5.75+ site, Os+5.75+ is bonded to six O2- atoms to form OsO6 octahedra that share corners with six OsO6 octahedra, edges with two equivalent TlO8 hexagonal bipyramids, and edges with four equivalent TlO7 hexagonal pyramids. The corner-sharing octahedra tilt angles range from 35–46°. There are a spread of Os–O bond distances ranging from 1.93–2.00 Å. There are two inequivalent Tl1+ sites. In the first Tl1+ site, Tl1+ is bonded to eight O2- atoms to form distorted TlO8 hexagonal bipyramids that share edges with four equivalent TlO8 hexagonal bipyramids, edges with two equivalent TlO7 hexagonal pyramids, and edges with six OsO6 octahedra. There are a spread of Tl–O bond distances ranging from 2.23–2.62 Å. In the second Tl1+ site, Tl1+ is bonded to seven O2- atoms to form distorted TlO7 hexagonal pyramids that share corners with three equivalent TlO7 hexagonal pyramids, edges with two equivalent TlO8 hexagonal bipyramids, an edgeedge with one TlO7 hexagonal pyramid, and edges with six OsO6 octahedra. There are a spread of Tl–O bond distances ranging from 2.39–2.79 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Os+5.75+ and two equivalent Tl1+ atoms. In the second O2- site, O2- is bonded to four equivalent Tl1+ atoms to form corner-sharing OTl4 tetrahedra. In the third O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Os+5.75+ and two equivalent Tl1+ atoms. In the fourth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Os+5.75+ and two equivalent Tl1+ atoms. In the fifth O2- site, O2- is bonded to four Tl1+ atoms to form corner-sharing OTl4 tetrahedra. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to two Os+5.75+ and two Tl1+ atoms. In the seventh O2- site, O2- is bonded in a 4-coordinate geometry to two equivalent Os+5.75+ and two equivalent Tl1+ atoms. In the eighth O2- site, O2- is bonded in a distorted bent 150 degrees geometry to two equivalent Os+5.75+ and two equivalent Tl1+ atoms. In the ninth O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Os+5.75+ and two equivalent Tl1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Local Environment of Superoxide Radical Formed on the TiO 2 Surface Produced From Ti(OiPr) 4 Exposed to H 2 O 2

A selective heterogeneous catalyst with the superoxide anion O 2 •– stable at room temperature, generated by treating Ti(OR) 4 (R=iPr, nBu) with H 2 O 2 , was previously reported and used for the oxidation of organic compounds. Furthermore, it was proposed that exceptional stability of the O 2 •– is resulted from its stabilization near Ti +4 cation on the TiO 2 surface with participation of water molecules and/or OH groups. In this article, we performed high-resolution pulsed EPR study on the O 2 •– in this catalyst with the aim to obtain quantitative information about its interactions with the surrounding molecules. Our data has shown that the O 2 •– is involved in weak hyperfine interactions with protons in the nearest environment, which do not exceed a value of 2 MHz. It corresponds to an Os…H distance of ≥ 3 Å that exclude the formation of hydrogen bonds. The analysis of possible structures of O 2 •– adsorption on TiO 2 surface taking into account our results and lack of radical mobility at room temperature previously observed in EPR spectra led us to suggest that the O 2 •– is stabilized in the form of superoxo bridge coordinated with two titanium atoms.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
NASA NTRS1973

SUMC/MPOS/HAL interface study

The implementation of the HAL/S language on the IBM-360, and in particular the mechanization of its real time, I/O, and error control statements within the OS-360 environment is described. The objectives are twofold: (1) An analysis and general description of HAL/S real time, I/O, and error control statements and the structure required to mechanize these statements. The emphasis is on describing the logical functions performed upon execution of each HAL statement rather than defining whether it is accomplished by the compiler or operating system. (2) An identification of the OS-360 facilities required during execution of HAL/S code as implemented for the current HAL/S-360 compiler; and an evaluation of the aspects involved with interfacing HAL/S with the SUMC operating system utilizing either the HAL/S-360 compiler or by designing a new HAL/S-SUMC compiler.

Saponaro, J. A.↗
DOE OSTI2020

Materials Data on Ce(BOs)2 by Materials Project

CeOs2B2 crystallizes in the orthorhombic Fddd space group. The structure is three-dimensional. Ce3+ is bonded in a 4-coordinate geometry to four equivalent Os+1.50- atoms. All Ce–Os bond lengths are 3.01 Å. Os+1.50- is bonded in a 4-coordinate geometry to two equivalent Ce3+ and four equivalent B atoms. There are two shorter (2.09 Å) and two longer (2.17 Å) Os–B bond lengths. B is bonded in a 4-coordinate geometry to four equivalent Os+1.50- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Y3(Si3Os)4 by Materials Project

Y3(OsSi3)4 crystallizes in the orthorhombic Cmce space group. The structure is three-dimensional. there are two inequivalent Y3+ sites. In the first Y3+ site, Y3+ is bonded in a 4-coordinate geometry to four Os+0.25- and twelve Si+0.67- atoms. There are two shorter (3.25 Å) and two longer (3.27 Å) Y–Os bond lengths. There are a spread of Y–Si bond distances ranging from 3.00–3.24 Å. In the second Y3+ site, Y3+ is bonded in a 12-coordinate geometry to six Os+0.25- and twelve Si+0.67- atoms. There are two shorter (3.15 Å) and four longer (3.22 Å) Y–Os bond lengths. There are a spread of Y–Si bond distances ranging from 3.04–3.11 Å. There are twelve inequivalent Os+0.25- sites. In the first Os+0.25- site, Os+0.25- is bonded in a 7-coordinate geometry to two equivalent Y3+ and seven Si+0.67- atoms. There are a spread of Os–Si bond distances ranging from 2.37–2.54 Å. In the second Os+0.25- site, Os+0.25- is bonded in a 7-coordinate geometry to two equivalent Y3+ and seven Si+0.67- atoms. There are a spread of Os–Si bond distances ranging from 2.37–2.54 Å. In the third Os+0.25- site, Os+0.25- is bonded in a 7-coordinate geometry to two equivalent Y3+ and seven Si+0.67- atoms. There are a spread of Os–Si bond distances ranging from 2.37–2.54 Å. In the fourth Os+0.25- site, Os+0.25- is bonded in a 5-coordinate geometry to five Y3+ and five Si+0.67- atoms. The Os–Y bond length is 3.15 Å. There are one shorter (2.34 Å) and four longer (2.43 Å) Os–Si bond lengths. In the fifth Os+0.25- site, Os+0.25- is bonded in a 5-coordinate geometry to five Y3+ and five Si+0.67- atoms. There are one shorter (2.34 Å) and four longer (2.43 Å) Os–Si bond lengths. In the sixth Os+0.25- site, Os+0.25- is bonded in a 5-coordinate geometry to five Y3+ and five Si+0.67- atoms. The Os–Y bond length is 3.15 Å. There are one shorter (2.34 Å) and four longer (2.43 Å) Os–Si bond lengths. In the seventh Os+0.25- site, Os+0.25- is bonded in a 7-coordinate geometry to two equivalent Y3+ and seven Si+0.67- atoms. Both Os–Y bond lengths are 3.22 Å. There are a spread of Os–Si bond distances ranging from 2.37–2.54 Å. In the eighth Os+0.25- site, Os+0.25- is bonded in a 7-coordinate geometry to two equivalent Y3+ and seven Si+0.67- atoms. Both Os–Y bond lengths are 3.22 Å. There are a spread of Os–Si bond distances ranging from 2.37–2.54 Å. In the ninth Os+0.25- site, Os+0.25- is bonded in a 7-coordinate geometry to two equivalent Y3+ and seven Si+0.67- atoms. Both Os–Y bond lengths are 3.22 Å. There are a spread of Os–Si bond distances ranging from 2.37–2.54 Å. In the tenth Os+0.25- site, Os+0.25- is bonded in a 5-coordinate geometry to five Y3+ and five Si+0.67- atoms. There are a spread of Os–Y bond distances ranging from 3.15–3.27 Å. There are one shorter (2.34 Å) and four longer (2.43 Å) Os–Si bond lengths. In the eleventh Os+0.25- site, Os+0.25- is bonded in a 5-coordinate geometry to five Y3+ and five Si+0.67- atoms. There are a spread of Os–Y bond distances ranging from 3.15–3.27 Å. There are one shorter (2.34 Å) and four longer (2.43 Å) Os–Si bond lengths. In the twelfth Os+0.25- site, Os+0.25- is bonded in a 5-coordinate geometry to five Y3+ and five Si+0.67- atoms. There are a spread of Os–Y bond distances ranging from 3.15–3.27 Å. There are one shorter (2.34 Å) and four longer (2.43 Å) Os–Si bond lengths. There are seven inequivalent Si+0.67- sites. In the first Si+0.67- site, Si+0.67- is bonded in a 1-coordinate geometry to four equivalent Y3+, one Os+0.25-, and four Si+0.67- atoms. All Si–Si bond lengths are 2.47 Å. In the second Si+0.67- site, Si+0.67- is bonded in a 9-coordinate geometry to two equivalent Y3+, three Os+0.25-, and four Si+0.67- atoms. The Si–Os bond length is 2.37 Å. There are two shorter (2.63 Å) and two longer (2.64 Å) Si–Si bond lengths. In the third Si+0.67- site, Si+0.67- is bonded in a 9-coordinate geometry to two equivalent Y3+, three Os+0.25-, and four Si+0.67- atoms. There are two shorter (2.63 Å) and two longer (2.64 Å) Si–Si bond lengths. In the fourth Si+0.67- site, Si+0.67- is bonded in a 9-coordinate geometry to two equivalent Y3+, three Os+0.25-, and four Si+0.67- atoms. There are two shorter (2.63 Å) and two longer (2.64 Å) Si–Si bond lengths. In the fifth Si+0.67- site, Si+0.67- is bonded in a 2-coordinate geometry to three Y3+, two Os+0.25-, and four Si+0.67- atoms. There are one shorter (2.59 Å) and one longer (2.68 Å) Si–Si bond lengths. In the sixth Si+0.67- site, Si+0.67- is bonded in a 2-coordinate geometry to three Y3+, two Os+0.25-, and four Si+0.67- atoms. In the seventh Si+0.67- site, Si+0.67- is bonded in a 9-coordinate geometry to two equivalent Y3+, three Os+0.25-, and four Si+0.67- atoms. There are one shorter (3.04 Å) and one longer (3.05 Å) Si–Y bond lengths. There are two shorter (2.63 Å) and two longer (2.64 Å) Si–Si bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2023

The Recovery of Medical Isotope 188 W from Irradiated W Metal Target - A New Approach

Tungsten-188 is in widespread use in 188 W(t 1/2 = 69 d )/ 188 Re(t 1/2 = 16.9 h ) biomedical generators. Oak Ridge National Laboratory has been providing this product to the world since 1999. At ORNL, 188 W is produced via irradiation in ORNL’s High Flux Isotope Reactor (HFIR). Enriched 186 W targets in the form of sintered metallic pellets or rings achieve a compact loading in the irradiation vessel, providing a high yield per unit target. The enrichment of the target is >90% 186 W, and this isotope undergoes double neutron capture to produce the desired 188 W product. While 188 W is produced by neutron bombardment, 191 Os(t 1/2 = 15.4 d ) is simultaneously produced as a by-product and expected to be separated from 188 W by postirradiation treatment.In the current processing pathway, the irradiated W metal rings are first converted into an oxide form of WO 3 by heating the irradiated W metal target at 750°C in a quartz reaction vessel inside a vertical furnace under a constant flow of air. During heating, W metal reacts with oxygen in the air to produce WO 3 , which is soluble in 6 M NaOH for preparation of 188 W product. This oxidation process also converts 188 Os (the decay daughter of 188 W) and 191 Os (15.4 d , the irradiation produced byproduct) into OsO 4 , a highly volatile and toxic gas. The gaseous effluents driven from the quartz reaction vessel are passed through a scrubbing array to remove OsO 4 before the air is discharged from the process. This heterogeneous oxidation method simultaneously achieves goals of (1) converting metal target to a soluble oxide form and (2) removing volatile OsO 4 away from the solid WO 3 product by air flow and absorbing the harmful Os species by the scrubbing array. But this method has two potential problems as well: (1) O 2 reacts with only W metal at high temperatures, not with W alloyed with other elements. The O 2 –W reaction will be retarded when formation of WRe or WC occurs, or even when a layer of non-W materials on the surface of the irradiated W rings.; (2) 100% absorption of OsO 4 of high yield (>90%) from the reaction of Os + O 2 is a strict requirement to the OsO 4 scrubbing system--so NaOH scrubbers of a redundant size (2x 1.5 L) are in use for safety reasons.To resolve above two potential problems, direct dissolution of the irradiated W metal target by a selected reagent is a preferred pathway to avoid heating step with generation of tremendous amount of volatile OsO 4 . Hydrogen peroxide (H 2 O 2 ) is such a candidate to dissolve W in forms of either metal or alloys, although literature lacks information of solubilities of Re or Os in H 2 O 2 . With experimental results of dissolving non-radioactive W, Re and Os in H 2 O 2 under various conditions, this report illustrates a method of H 2 O 2 dissolution for irradiated W target, with a complete dissolution of W and Re, but ≤10% dissolution of Os (converted into gaseous OsO 4 and carried out into a scrubbing for absorption) during processing irradiated W target. The portion of undissolved Os can be separated from W solution by a follow up filtration step. Solubilities of W, Re and Os in H 2 O 2 at a temperature range from 14° to 50°C are presented. And a dissolution rate of W metal per surface area of W metal in H 2 O 2 is calculated based on results of dissolving a W metal cylinder of known surface area in H 2 O 2 at room temperature without stirring.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2020

Materials Data on CeGa4Os by Materials Project

CeOsGa4 crystallizes in the orthorhombic Pmma space group. The structure is three-dimensional. there are two inequivalent Ce sites. In the first Ce site, Ce is bonded in a 10-coordinate geometry to twelve Ga atoms. There are a spread of Ce–Ga bond distances ranging from 3.05–3.51 Å. In the second Ce site, Ce is bonded in a 12-coordinate geometry to four equivalent Os and twelve Ga atoms. All Ce–Os bond lengths are 3.48 Å. There are a spread of Ce–Ga bond distances ranging from 2.99–3.45 Å. There are two inequivalent Os sites. In the first Os site, Os is bonded in a 12-coordinate geometry to eight Ga atoms. There are a spread of Os–Ga bond distances ranging from 2.59–2.67 Å. In the second Os site, Os is bonded in a 8-coordinate geometry to two equivalent Ce and eight Ga atoms. There are a spread of Os–Ga bond distances ranging from 2.58–2.70 Å. There are six inequivalent Ga sites. In the first Ga site, Ga is bonded to six Ce and six Ga atoms to form face-sharing GaCe6Ga6 cuboctahedra. There are two shorter (2.78 Å) and four longer (2.80 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Ce, two equivalent Os, and six Ga atoms. There are four shorter (2.70 Å) and two longer (2.86 Å) Ga–Ga bond lengths. In the third Ga site, Ga is bonded in a 10-coordinate geometry to two equivalent Ce, three Os, and five Ga atoms. There are a spread of Ga–Ga bond distances ranging from 2.77–2.81 Å. In the fourth Ga site, Ga is bonded in a 5-coordinate geometry to four Ce, two equivalent Os, and one Ga atom. In the fifth Ga site, Ga is bonded in a 2-coordinate geometry to three Ce, two Os, and four Ga atoms. The Ga–Ga bond length is 2.77 Å. In the sixth Ga site, Ga is bonded in a 10-coordinate geometry to two Ce, two equivalent Os, and six Ga atoms. The Ga–Ga bond length is 2.80 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Specific Ion and Electric Field Controlled Diverse Ion Distribution and Electroosmotic Transport in a Polyelectrolyte Brush Grafted Nanochannel

Controlling ion distribution inside a charged nanochannel is central to using such channels in diverse applications. Here, we show the possibility of using a charged polyelectrolyte (PE) brush grafted nanochannel for triggering diverse nanoscopic ion distribution and nanofluidic electroosmotic transport by controlling the valence and size of the counterions (that screen the charges of the PE brushes) and the strength of an externally applied axial electric field. We atomistically simulate separate cases of fully charged Polyacrylic acid (PAA) brush functionalized nanochannels with Na + , Cs + , Ca 2+ , Ba 2+ , and Y 3+ counterions screening the PE charges. Four key findings emerge from our simulations. First, we find that the counterions with a greater valence and a smaller size prefer to remain localized inside the brush layer. Second, for the case where there is an added chloride salt with the same cation (as the screening counterions), there are more coions (Cl - ions) in the brush-free bulk than counterions (for counterions Na + , Ca 2+ , Ba 2+ , Y 3+ ): this is a manifestation of the overscreening (OS) of the PE brush layer. Contrastingly, the number of Cs + ions remain higher than the Cl - ions inside the brush-free bulk, ensuring that there is no OS effect for this case. Third, large applied electric field enables a few Na + , Cs + , and Ba 2+ counterions to leave the brush layer and to go to the bulk: this makes the OS of the PE brush layer disappear for the cases of PE brushes being screened by the Na+ and Ba 2+ ions. On the other hand, no such electric-field-mediated disappearance of OS is observed for the cases of Ca 2+ and Y 3+ screening counterions; we attribute this to the firm attachment of these counterions to the negatively charged monomers. Free energy associated to a counterion binding to a PE chain corroborates this diversity in the counterion-specific response to the applied electric field. Lastly, we demonstrate that such diverse ion distributions, along with specific electric-field-strength-dependent ion properties, lead to (1) EOS transport in nanochannels grafted with PAA brushes screened with Cs + ions to be always counterion dominated, (2) EOS transport in nanochannels grafted with PAA brushes screened with Ca 2+ and Y 3+ ions to be always coion dominated, and (3) EOS transport in nanochannels grafted with PAA brushes screened with Na + and Ba 2+ ions to be coion dominated for smaller electric fields and counterion dominated for larger electric fields.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗