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At least 793 records · Page 44
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on NaCdP2NO10 by Materials Project

NaCdP2NO10 crystallizes in the monoclinic Cc space group. The structure is three-dimensional. Na is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Na–O bond distances ranging from 2.33–2.94 Å. Cd is bonded to six O atoms to form distorted CdO6 octahedra that share corners with five PO4 tetrahedra. There are a spread of Cd–O bond distances ranging from 2.19–2.46 Å. There are two inequivalent P sites. In the first P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with three equivalent CdO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 40–58°. There are a spread of P–O bond distances ranging from 1.51–1.63 Å. In the second P site, P is bonded to four O atoms to form PO4 tetrahedra that share corners with two equivalent CdO6 octahedra and a cornercorner with one PO4 tetrahedra. The corner-sharing octahedra tilt angles range from 52–58°. There are a spread of P–O bond distances ranging from 1.51–1.65 Å. N is bonded in a single-bond geometry to one O atom. The N–O bond length is 1.20 Å. There are ten inequivalent O sites. In the first O site, O is bonded in a distorted trigonal planar geometry to two equivalent Na and one P atom. In the second O site, O is bonded in a distorted single-bond geometry to one N and one O atom. The O–O bond length is 1.40 Å. In the third O site, O is bonded in a distorted bent 120 degrees geometry to one Na and one O atom. In the fourth O site, O is bonded in a water-like geometry to one Na and one Cd atom. In the fifth O site, O is bonded in a distorted bent 120 degrees geometry to one Na and two P atoms. In the sixth O site, O is bonded in a distorted bent 120 degrees geometry to one Cd and one P atom. In the seventh O site, O is bonded in a distorted bent 150 degrees geometry to one Cd and one P atom. In the eighth O site, O is bonded in a bent 120 degrees geometry to one Cd and one P atom. In the ninth O site, O is bonded in a distorted trigonal planar geometry to one Na, one Cd, and one P atom. In the tenth O site, O is bonded in a distorted bent 120 degrees geometry to one Cd and one P atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg2Cd by Materials Project

Mg2Cd crystallizes in the trigonal R32 space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to eight Mg and four equivalent Cd atoms to form distorted MgMg8Cd4 cuboctahedra that share corners with eighteen equivalent MgMg8Cd4 cuboctahedra, edges with eight equivalent CdMg9Cd3 cuboctahedra, edges with ten MgMg8Cd4 cuboctahedra, faces with eight equivalent CdMg9Cd3 cuboctahedra, and faces with twelve MgMg8Cd4 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.11–3.18 Å. There are two shorter (3.16 Å) and two longer (3.19 Å) Mg–Cd bond lengths. In the second Mg site, Mg is bonded to six equivalent Mg and six equivalent Cd atoms to form distorted MgMg6Cd6 cuboctahedra that share corners with six equivalent MgMg6Cd6 cuboctahedra, corners with twelve equivalent CdMg9Cd3 cuboctahedra, edges with eighteen MgMg8Cd4 cuboctahedra, faces with eight equivalent CdMg9Cd3 cuboctahedra, and faces with twelve equivalent MgMg8Cd4 cuboctahedra. All Mg–Cd bond lengths are 3.12 Å. Cd is bonded to nine Mg and three equivalent Cd atoms to form distorted CdMg9Cd3 cuboctahedra that share corners with six equivalent MgMg6Cd6 cuboctahedra, corners with twelve equivalent CdMg9Cd3 cuboctahedra, edges with six equivalent CdMg9Cd3 cuboctahedra, edges with twelve equivalent MgMg8Cd4 cuboctahedra, faces with four equivalent CdMg9Cd3 cuboctahedra, and faces with sixteen MgMg8Cd4 cuboctahedra. All Cd–Cd bond lengths are 3.12 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg2Cd by Materials Project

Mg2Cd crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to eight Mg and four equivalent Cd atoms to form distorted MgMg8Cd4 cuboctahedra that share corners with six equivalent CdMg6Cd6 cuboctahedra, corners with twelve MgMg10Cd2 cuboctahedra, edges with three equivalent CdMg6Cd6 cuboctahedra, edges with fifteen MgMg8Cd4 cuboctahedra, faces with eight equivalent CdMg6Cd6 cuboctahedra, and faces with twelve MgMg8Cd4 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.17–3.23 Å. There are two shorter (3.11 Å) and two longer (3.14 Å) Mg–Cd bond lengths. In the second Mg site, Mg is bonded to ten Mg and two equivalent Cd atoms to form distorted MgMg10Cd2 cuboctahedra that share corners with six equivalent CdMg6Cd6 cuboctahedra, corners with twelve MgMg8Cd4 cuboctahedra, edges with seven equivalent MgMg8Cd4 cuboctahedra, edges with eleven equivalent CdMg6Cd6 cuboctahedra, faces with four equivalent CdMg6Cd6 cuboctahedra, and faces with sixteen MgMg8Cd4 cuboctahedra. There are two shorter (3.16 Å) and two longer (3.23 Å) Mg–Mg bond lengths. Both Mg–Cd bond lengths are 3.11 Å. Cd is bonded to six Mg and six equivalent Cd atoms to form distorted CdMg6Cd6 cuboctahedra that share corners with six equivalent CdMg6Cd6 cuboctahedra, corners with twelve MgMg8Cd4 cuboctahedra, edges with four equivalent CdMg6Cd6 cuboctahedra, edges with fourteen MgMg8Cd4 cuboctahedra, faces with eight equivalent CdMg6Cd6 cuboctahedra, and faces with twelve MgMg8Cd4 cuboctahedra. There are four shorter (3.19 Å) and two longer (3.23 Å) Cd–Cd bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Cd8Cu7P30 by Materials Project

Cu7Cd8P30 crystallizes in the triclinic P1 space group. The structure is three-dimensional. there are seven inequivalent Cu+1.43+ sites. In the first Cu+1.43+ site, Cu+1.43+ is bonded to four P+0.87- atoms to form CuP4 tetrahedra that share corners with twelve PCdCuP2 tetrahedra. There are two shorter (2.33 Å) and two longer (2.34 Å) Cu–P bond lengths. In the second Cu+1.43+ site, Cu+1.43+ is bonded to four P+0.87- atoms to form CuP4 tetrahedra that share corners with twelve PCdCuP2 tetrahedra. There are one shorter (2.32 Å) and three longer (2.33 Å) Cu–P bond lengths. In the third Cu+1.43+ site, Cu+1.43+ is bonded to four P+0.87- atoms to form CuP4 tetrahedra that share corners with twelve PCdCuP2 tetrahedra. There are one shorter (2.33 Å) and three longer (2.34 Å) Cu–P bond lengths. In the fourth Cu+1.43+ site, Cu+1.43+ is bonded in a trigonal non-coplanar geometry to three P+0.87- atoms. There are two shorter (2.30 Å) and one longer (2.33 Å) Cu–P bond lengths. In the fifth Cu+1.43+ site, Cu+1.43+ is bonded in a trigonal non-coplanar geometry to three P+0.87- atoms. All Cu–P bond lengths are 2.32 Å. In the sixth Cu+1.43+ site, Cu+1.43+ is bonded in a trigonal non-coplanar geometry to three P+0.87- atoms. All Cu–P bond lengths are 2.32 Å. In the seventh Cu+1.43+ site, Cu+1.43+ is bonded in a trigonal non-coplanar geometry to three P+0.87- atoms. There are a spread of Cu–P bond distances ranging from 2.28–2.31 Å. There are eight inequivalent Cd2+ sites. In the first Cd2+ site, Cd2+ is bonded in a 3-coordinate geometry to three P+0.87- atoms. There are a spread of Cd–P bond distances ranging from 2.57–2.66 Å. In the second Cd2+ site, Cd2+ is bonded in a 3-coordinate geometry to three P+0.87- atoms. There are a spread of Cd–P bond distances ranging from 2.56–2.66 Å. In the third Cd2+ site, Cd2+ is bonded in a 3-coordinate geometry to three P+0.87- atoms. There are a spread of Cd–P bond distances ranging from 2.56–2.67 Å. In the fourth Cd2+ site, Cd2+ is bonded in a 3-coordinate geometry to three P+0.87- atoms. There are a spread of Cd–P bond distances ranging from 2.56–2.65 Å. In the fifth Cd2+ site, Cd2+ is bonded in a 3-coordinate geometry to three P+0.87- atoms. There are a spread of Cd–P bond distances ranging from 2.56–2.65 Å. In the sixth Cd2+ site, Cd2+ is bonded in a 3-coordinate geometry to three P+0.87- atoms. There are one shorter (2.54 Å) and two longer (2.66 Å) Cd–P bond lengths. In the seventh Cd2+ site, Cd2+ is bonded in a 3-coordinate geometry to three P+0.87- atoms. There are two shorter (2.56 Å) and one longer (2.65 Å) Cd–P bond lengths. In the eighth Cd2+ site, Cd2+ is bonded in a 3-coordinate geometry to three P+0.87- atoms. There are a spread of Cd–P bond distances ranging from 2.56–2.65 Å. There are thirty inequivalent P+0.87- sites. In the first P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are a spread of P–P bond distances ranging from 2.19–2.22 Å. In the second P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are a spread of P–P bond distances ranging from 2.19–2.22 Å. In the third P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are one shorter (2.19 Å) and two longer (2.22 Å) P–P bond lengths. In the fourth P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are a spread of P–P bond distances ranging from 2.20–2.22 Å. In the fifth P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are a spread of P–P bond distances ranging from 2.19–2.22 Å. In the sixth P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are one shorter (2.19 Å) and two longer (2.22 Å) P–P bond lengths. In the seventh P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are one shorter (2.19 Å) and two longer (2.22 Å) P–P bond lengths. In the eighth P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are two shorter (2.21 Å) and one longer (2.23 Å) P–P bond lengths. In the ninth P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are one shorter (2.19 Å) and two longer (2.22 Å) P–P bond lengths. In the tenth P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are one shorter (2.19 Å) and two longer (2.20 Å) P–P bond lengths. In the eleventh P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are one shorter (2.19 Å) and two longer (2.20 Å) P–P bond lengths. In the twelfth P+0.87- site, P+0.87- is bonded to one Cu+1.43+ and three P+0.87- atoms to form corner-sharing PCuP3 tetrahedra. There are one shorter (2.19 Å) and two longer (2.20 Å) P–P bond lengths. In the thirteenth P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form PCdCuP2 tetrahedra that share corners with two equivalent CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the fourteenth P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form PCdCuP2 tetrahedra that share corners with two equivalent CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the fifteenth P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form PCdCuP2 tetrahedra that share corners with two equivalent CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the sixteenth P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form PCdCuP2 tetrahedra that share corners with two CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the seventeenth P+0.87- site, P+0.87- is bonded to two Cu+1.43+ and two P+0.87- atoms to form PCu2P2 tetrahedra that share corners with two CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the eighteenth P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form PCdCuP2 tetrahedra that share corners with two CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the nineteenth P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form PCdCuP2 tetrahedra that share corners with two CuP4 tetrahedra and corners with eight PCd2P2 tetrahedra. In the twentieth P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form PCdCuP2 tetrahedra that share corners with two CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the twenty-first P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form PCdCuP2 tetrahedra that share corners with two CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the twenty-second P+0.87- site, P+0.87- is bonded to two Cd2+ and two P+0.87- atoms to form PCd2P2 tetrahedra that share corners with two CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the twenty-third P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form distorted PCdCuP2 tetrahedra that share corners with two CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the twenty-fourth P+0.87- site, P+0.87- is bonded to two Cd2+ and two P+0.87- atoms to form PCd2P2 tetrahedra that share corners with two CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the twenty-fifth P+0.87- site, P+0.87- is bonded to one Cu+1.43+, one Cd2+, and two P+0.87- atoms to form distorted PCdCuP2 tetrahedra that share corners with two equivalent CuP4 tetrahedra and corners with eight PCd2P2 tetrahedra. In the twenty-sixth P+0.87- site, P+0.87- is bonded to two Cd2+ and two P+0.87- atoms to form PCd2P2 tetrahedra that share corners with two equivalent CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the twenty-seventh P+0.87- site, P+0.87- is bonded to two Cd2+ and two P+0.87- atoms to form PCd2P2 tetrahedra that share corners with two equivalent CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the twenty-eighth P+0.87- site, P+0.87- is bonded to two Cd2+ and two P+0.87- atoms to form PCd2P2 tetrahedra that share corners with two equivalent CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the twenty-ninth P+0.87- site, P+0.87- is bonded to two Cd2+ and two P+0.87- atoms to form PCd2P2 tetrahedra that share corners with two equivalent CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra. In the thirtieth P+0.87- site, P+0.87- is bonded to two Cd2+ and two P+0.87- atoms to form PCd2P2 tetrahedra that share corners with two equivalent CuP4 tetrahedra and corners with eight PCdCuP2 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Mg2Cd by Materials Project

Mg2Cd crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Mg sites. In the first Mg site, Mg is bonded to six Mg and six equivalent Cd atoms to form distorted MgMg6Cd6 cuboctahedra that share corners with six equivalent CdMg8Cd4 cuboctahedra, corners with twelve MgMg6Cd6 cuboctahedra, edges with seven equivalent CdMg8Cd4 cuboctahedra, edges with eleven MgMg6Cd6 cuboctahedra, faces with six equivalent CdMg8Cd4 cuboctahedra, and faces with fourteen MgMg6Cd6 cuboctahedra. There are a spread of Mg–Mg bond distances ranging from 3.12–3.21 Å. All Mg–Cd bond lengths are 3.13 Å. In the second Mg site, Mg is bonded to ten Mg and two equivalent Cd atoms to form distorted MgMg10Cd2 cuboctahedra that share corners with six equivalent CdMg8Cd4 cuboctahedra, corners with twelve MgMg6Cd6 cuboctahedra, edges with seven MgMg6Cd6 cuboctahedra, edges with eleven equivalent CdMg8Cd4 cuboctahedra, faces with four equivalent CdMg8Cd4 cuboctahedra, and faces with sixteen MgMg6Cd6 cuboctahedra. There are four shorter (3.15 Å) and two longer (3.21 Å) Mg–Mg bond lengths. Both Mg–Cd bond lengths are 3.11 Å. Cd is bonded to eight Mg and four equivalent Cd atoms to form distorted CdMg8Cd4 cuboctahedra that share corners with six equivalent CdMg8Cd4 cuboctahedra, corners with twelve MgMg6Cd6 cuboctahedra, edges with eighteen MgMg6Cd6 cuboctahedra, faces with ten MgMg6Cd6 cuboctahedra, and faces with ten equivalent CdMg8Cd4 cuboctahedra. There are two shorter (3.13 Å) and two longer (3.21 Å) Cd–Cd bond lengths.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Basin scale distributions of dissolved manganese, nickel, zinc and cadmium in the Mediterranean Sea

Samples for dissolved trace metal concentrations were collected during GEOTRACES expedition GA04-N in summer/spring in the Mediterranean Sea, starting in the Atlantic Ocean and sampling both deep basins of the Mediterranean Sea. Outflow of Mediterranean Outflow Water leads to elevated concentrations of Mn, Ni and Zn in the Atlantic Ocean, but a concentration minimum in the Atlantic distribution of Cd. Nevertheless, when comparing the in- and outflow, the Mediterranean is a net source of Cd to the Atlantic Ocean. Surface concentrations of Mn, Ni, Zn and Cd are elevated in the Mediterranean relative to the Atlantic Ocean where Ni and Cd gradually increased along the eastward surface water flow path, Zn reached a homogenous concentration in the order of 1 to 1.5 nM, and Mn displayed a patchy surface distribution. The observed differences are attributable to the different dynamics of their biogeochemical cycling, notably the partitioning between the dissolved and particulate phases due to biological uptake, scavenging and possibly organic complexation. The elevated surface concentrations of Mn, Ni, Zn and Cd in the Mediterranean are derived from atmospheric deposition, where most likely Zn and Cd are mainly sourced from anthropogenic origin, Mn mostly from lithogenic origin and Ni from both anthropogenic and lithogenic origin. Dissolved Zn and Cd, as well as phosphate and nitrate, display striking inter-basin fractionations with elevated concentrations in the deep water of the western basin compared to the deep eastern basin, without a coinciding increase in the apparent oxygen utilization. Given that physical circulation or contribution from biogenic particulate metals cannot explain the elevated dissolved concentrations, an external non-biological source is required. This source is most likely a vertical flux of metal laden particles dissolving through the water column of the western Mediterranean where these particles, most likely from anthropogenic origin, are derived from either atmospheric deposition or particulate material deposited on the continental shelves that makes its way into the deep basin. Furthermore, to confirm or detect trends in dissolved metal concentrations in the deep basin, regular basin wide assessments of the trace metal distributions in the Mediterranean are needed. The distributions of Mn, Ni, Zn and Cd in the Sea of Marmara illustrate that all of these metals can be affected by anthropogenic surface sources and highlight the different susceptibilities of the dissolved metal distributions to supply from remineralization, and to removal through scavenging. This study provides a first baseline to assess future changes and underlines that the Mediterranean marine environment is susceptible to anthropogenic disturbances, with varying effects for different metals due to differing source strengths and biogeochemical cycles.

58 GEOSCIENCES↗
DOE OSTI2020

Kinetics and Optimization of the Lysine–Isopeptide Bond Forming Sortase Enzyme from Corynebacterium diphtheriae

Site-specifically modified protein bioconjugates have important applications in biology, chemistry, and medicine. Functionalizing specific protein side chains with enzymes using mild reaction conditions is of significant interest, but remains challenging. Recently, the lysine–isopeptide bond forming activity of the sortase enzyme that builds surface pili in Corynebacterium diphtheriae ( Cd SrtA) has been reconstituted in vitro. A mutationally activated form of Cd SrtA was shown to be a promising bioconjugating enzyme that can attach Leu-Pro-Leu-Thr-Gly peptide fluorophores to a specific lysine residue within the N-terminal domain of the SpaA protein ( N SpaA), enabling the labeling of target proteins that are fused to N SpaA. Here we present a detailed analysis of the Cd SrtA catalyzed protein labeling reaction. We show that the first step in catalysis is rate limiting, which is the formation of the Cd SrtA-peptide thioacyl intermediate that subsequently reacts with a lysine ε-amine in N SpaA. This intermediate is surprisingly stable, limiting spurious proteolysis of the peptide substrate. We report the discovery of a new enzyme variant ( Cd SrtA Δ ) that has significantly improved transpeptidation activity, because it completely lacks an inhibitory polypeptide appendage (“lid”) that normally masks the active site. We show that the presence of the lid primarily impairs formation of the thioacyl intermediate and not the recognition of the N SpaA substrate. Quantitative measurements reveal that Cd SrtA Δ generates its cross-linked product with a catalytic turnover number of 1.4 ± 0.004 h –1 and that it has apparent K M values of 0.16 ± 0.04 and 1.6 ± 0.3 mM for its N SpaA and peptide substrates, respectively. Cd SrtA Δ is 7-fold more active than previously studied variants, labeling >90% of N SpaA with peptide within 6 h. The results of this study further improve the utility of Cd SrtA as a protein labeling tool and provide insight into the enzyme catalyzed reaction that underpins protein labeling and pilus biogenesis.

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

A Spectroscopic and Computational Evaluation of Uranyl Oxo Engagement with Transition Metal Cations

Here, we report the synthesis and characterization of five novel Cd 2+ /UO 2 2+ heterometallic complexes that feature Cd-oxo distances ranging from 78 to 171% of the sum of the van der Waals radii for these atoms. This work marks an extension of our previously reported Pb 2+ /UO 2 2+ and Ag + /UO 2 2+ complexes, yet with much more pronounced structural and spectroscopic effects resulting from Cd-oxo interactions. We observe a major shift in the U═O symmetric stretch and significant uranyl bond length asymmetry. The ρbcp values calculated using Quantum Theory of Atoms in Molecules (QTAIM) support the asymmetry displayed in the structural data and indicate a decrease in covalent character in U═O bonds with close Cd-oxo contacts, more so than in related compounds containing Pb 2+ and Ag + . Second-order perturbation theory (SOPT) analysis reveals that O sp x → Cd s is the most significant orbital overlap and U═O bonding and antibonding orbitals also contribute to the interaction (U═O σ/π → Cd d and Cd s → U═O σ/π*). The overall stabilization energies for these interactions were lower than those in previously reported Pb 2+ cations, yet larger than related Ag + compounds. Analysis of the equatorial coordination sphere of the Cd 2+ /UO 2 2+ compounds (along with Pb 2+ /UO 2 2+ complexes) reveals that 7-coordinate uranium favors closer, stronger M n+ -oxo contacts. These results indicate that U═O bond strength tuning is possible with judicious choice of metal cations for oxo interactions and equatorial ligand coordination.

cations↗
DOE OSTI2025

Reexamining circular dichroism in photoemission from a topological insulator

The orbital angular momentum (OAM) of electron states is an essential ingredient for topological and quantum geometric quantities in solids. For example, Dirac surface states with helical spin- and orbital-angular momenta are a hallmark of a 3D topological insulator. Angle-resolved photoemission spectroscopy (ARPES) with variable circular light polarization, known as circular dichroism (CD), has been assumed to be a direct probe of OAM and, by proxy, of the Berry curvature of electronic bands in energy- and momentum-space. Indeed, topological surface states have been shown to exhibit angle-dependent CD (CDAD), and more broadly, CD is often interpreted as evidence of spin-orbit coupling. Meanwhile, it is well-established that CD originates from the photoemission matrix elements, which can have extrinsic contributions related to the experimental geometry and the inherently broken inversion symmetry at the sample surface. Therefore, it is important to broadly examine CD-ARPES to determine the scenarios in which it provides a robust probe of intrinsic material physics. We performed CD-ARPES on the canonical topological insulator Bi 2 ⁢Se 3 over a wide range of incident photon energies. Not only do we observe angle-dependent CD in the surface states, as expected, but we also find CD of a similar magnitude in virtually all bulk bands. Since OAM is forbidden by inversion symmetry in the bulk, we conclude this originates from symmetry-breaking in the photoemission process. Comparison with theoretical calculations supports this view and suggests that “hidden” OAM—localized to atomic sites within each unit cell—contributes significantly. Additional effects, including inter-atomic interference and final-state resonances, are responsible for the rapid variation of the CDAD signal with photon energy.

Sidilkover, Ittai [Tel Aviv University, Tel Aviv (↗
DOE OSTI2021

In 2 O 3 -Ga 2 O 3 Alloys as Potential Buffer Layers in CdTe Thin-Film Solar Cells

The efficiency of state-of-the-art Cd Te solar cells remains limited by the relatively low open-circuit voltage (V OC ). Improving the front interface is key towards realizing a higher V OC after achieving the necessary bulk carrier density and lifetime. Recent efforts in identifying buffer layers beyond Cd S have focused on Mg x Zn 1-x O, which offers tunability of the band offsets, but often suffers from high interfacial defect densities. Ga 2 O 3 -based buffer layers demonstrate tremendous improvements in interfacial defect passivation in crystalline silicon and dye-sensitized solar cells, leading to record high V OC , yet remain largely unexplored in Cd Te-based devices. Here, we perform hybrid density-functional-theory calculations to investigate pure Ga 2 O 3 and InGaO 3 alloys as a window layer in Cd Te photovoltaics. We report calculated band offsets for several pairs of solid-solid interfaces comprising transparent conducting oxide (TCO) and Cd Te heterojunctions. The results support a large conduction band offset spike of 0.67 eV for the Cd Te/Ga 2 O 3 (100) interface, while the offset is reduced to 0.18 eV for the InGaO 3 alloy and matches closely with the preferred optimum value of 0.2 eV. Device-level modeling tests of Cd Te solar cells integrating our results indicate that the highest efficiency is achieved with InGaO 3 acting both as a buffer layer and TCO. Finally, our results suggest that alloys of In 2 O 3 and Ga 2 O 3 may be attractive alternatives to Mg x Zn 1-x O for tailoring optimal conduction-band offsets of the buffer and TCO layers in high-efficiency Cd Te thin-film solar cells.

14 SOLAR ENERGY↗
DOE OSTI2022

Xanthohumol microbiome and signature in adults with Crohn’s disease (the XMaS trial): a protocol for a phase II triple-masked, placebo-controlled clinical trial

Xanthohumol (XN), a bioactive flavonoid from Humulus lupulus with anti-inflammatory properties, has potential benefits for patients with Crohn’s disease (CD), a type of inflammatory bowel disease. We recently completed and published results of a placebo-controlled phase I clinical trial demonstrating the safety and tolerability of 24 mg XN daily for 8 weeks. The present study aims to evaluate the safety and tolerability of the same dose of XN adults with clinically active CD in a placebo-controlled phase II clinical trial. Additional aims will assess the impact of XN on inflammatory biomarkers, platelet function, CD clinical activity, and stool microbial composition. The metabolism of XN will also be evaluated. This article provides a model protocol for consideration in investigations of XN or other natural products in disease states. A triple-masked, randomized, placebo-controlled trial will be conducted in adults with clinically active CD. Participants (n ≤ 32) will be randomized to either 24 mg encapsulated XN per day or placebo and followed for 8 weeks. Throughout the trial, participants will be queried for adverse events. Biomarkers of clinical safety, blood and stool markers of inflammation, platelet function, Crohn’s Disease Activity Index score, stool microbial composition, and XN metabolite profiles in blood, urine, and stool will be assessed every 2 weeks. We describe the protocol for a phase II clinical trial that evaluates the safety and tolerability of XN in adults with active CD, as well as evaluate metabolism and mechanisms that are relevant to CD and other diseases with underlying inflammation and/or gut permeability. The effects of XN on inflammatory biomarkers, platelet function, the microbiota, and multi-omics biomarkers measured in this phase II trial of adults with CD will be compared to the effects of XN in healthy adults in our previous phase I trial. The results of the study will advance the evidence guiding the use of XN in patients with CD.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2021

Training Restricted Boltzmann Machines With a D-Wave Quantum Annealer

Restricted Boltzmann Machine (RBM) is an energy-based, undirected graphical model. It is commonly used for unsupervised and supervised machine learning. Typically, RBM is trained using contrastive divergence (CD). However, training with CD is slow and does not estimate the exact gradient of the log-likelihood cost function. In this work, the model expectation of gradient learning for RBM has been calculated using a quantum annealer (D-Wave 2000Q), where obtaining samples is faster than Markov chain Monte Carlo (MCMC) used in CD. Training and classification results of RBM trained using quantum annealing are compared with the CD-based method. The performance of the two approaches is compared with respect to the classification accuracies, image reconstruction, and log-likelihood results. The classification accuracy results indicate comparable performances of the two methods. Image reconstruction and log-likelihood results show improved performance of the CD-based method. It is shown that the samples obtained from quantum annealer can be used to train an RBM on a 64-bit “bars and stripes” dataset with classification performance similar to an RBM trained with CD. Though training based on CD showed improved learning performance, training using a quantum annealer could be useful as it eliminates computationally expensive MCMC steps of CD.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Exogenous Hemin alleviated cadmium stress in maize (Zea mays L.) by enhancing leaf photosynthesis, AsA-GSH cycle and polyamine metabolism

Cadmium (Cd) stress is one of the principal abiotic stresses that inhibit maize growth. The research was to explore (hemin chloride) Hemin (100 μmol L −1 ) on photosynthesis, ascorbic acid (AsA)-glutathione (GSH) cycle system, and polyamine metabolism of maize under Cd stress (85 mg L −1 ) using nutrient solution hydroponics, with Tiannong 9 (Cd tolerant) and Fenghe 6 (Cd sensitive) as experimental materials. The results showed that Hemin can increase leaf photosynthetic pigment content and ameliorate the ratio of Chlorophyll a/chlorophyll b ( Chla / Chlb ) under Cd stress. The values of ribose 1, 5-diphosphate carboxylase/oxygenase (RuBPcase) and phosphoenolpyruvate carboxylase (PEPCase), and total xanthophyll cycle pool [(violoxanthin (V), antiflavin (A) and zeaxanthin (Z)] increased, which enhancing xanthophyll cycle (DEPS) de-epoxidation, and alleviating stomatal and non-stomatal limitation of leaf photosynthesis. Hemin significantly increased net photosynthetic rate ( P n ), stomatal conductance ( g s ), transpiration rate ( T r ), photochemical quenching coefficient ( qP ), PSII maximum photochemical efficiency ( F v /F m ), and electron transfer rate ( ETR ), which contributed to the improvement of the PSII photosynthetic system. Compared with Cd stress, Hemin can reduce thiobartolic acid reactant (TBARS) content, superoxide anion radical (O 2 − ) production rate, hydrogen peroxide (H 2 O 2 ) accumulation, and the extent of electrolyte leakage (EL); decreased the level of malondialdehyde (MDA) content and increased the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT); slowed the decrease in dehydroascorbic acid reductase (DHAR) and monodehydroascorbate reductase (MDHAR) activity and the increase in glutathione reductase (GR) and ascorbate peroxidase (APX) activity in leaves; promoted the increase in AsA and GSH content, decreased dehydroascorbic acid (DHA) and oxidized glutathione (GSSG), and increased AsA/DHA and GSH/GSSG ratios under Cd stress. Hemin promoted the increase of conjugated and bound polyamine content, and the conversion process speed of free putrescine (Put) to free spermine (Spm) and spermidine (Spd) in maize; decreased polyamine oxidase (PAO) activity and increased diamine oxidase (DAO), arginine decarboxylase (ADC), ornithine decarboxylase (ODC) and S-adenosylmethionine decarboxylase (SAMDC) enzyme activities in leaves under Cd stress.

Piao, Lin↗
DOE OSTI2024

Small-amplitude Compressible Magnetohydrodynamic Turbulence Modulated by Collisionless Damping in Earth’s Magnetosheath: Observation Matches Theory

Plasma turbulence is a ubiquitous dynamical process that transfers energy across many spatial and temporal scales and affects energetic particle transport. Recent advances in the understanding of compressible magnetohydrodynamic (MHD) turbulence demonstrate the important role of damping in shaping energy distributions on small scales, yet its observational evidence is still lacking. This study provides the first observational evidence of substantial collisionless damping (CD) modulation on the small-amplitude compressible MHD turbulence cascade in Earth’s magnetosheath using four Cluster spacecraft. Based on an improved compressible MHD decomposition algorithm, turbulence is decomposed into three eigenmodes: incompressible Alfvén modes and compressible slow and fast (magnetosonic) modes. Our observations demonstrate that CD enhances the anisotropy of compressible MHD modes because CD has a strong dependence on wave propagation angle. The wavenumber distributions of slow modes are mainly stretched perpendicular to the background magnetic field (B 0 ) and weakly modulated by CD. In contrast, fast modes are subjected to a more significant CD modulation. Fast modes exhibit a weak, scale-independent anisotropy above the CD truncation scale. Below the CD truncation scale, the anisotropy of fast modes enhances as wavenumbers increase. As a result, fast-mode fractions in the total energy of compressible modes decrease with the increase of perpendicular wavenumber (to B 0 ) or wave propagation angle. Our findings reveal how the turbulence cascade is shaped by CD and its consequences for anisotropies in the space environment.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Reexamining Circular Dichroism in Photoemission From a Topological Insulator

The orbital angular momentum (OAM) of electron states is an essential ingredient for topological and quantum geometric quantities in solids. For example, Dirac surface states with helical spin- and orbital-angular momenta are a hallmark of a 3D topological insulator. Angle-resolved photoemission spectroscopy (ARPES) with variable circular light polarization, known as circular dichroism (CD), has been assumed to be a direct probe of OAM and, by proxy, of the Berry curvature of electronic bands in energy- and momentum-space. Indeed, topological surface states have been shown to exhibit angle-dependent CD (CDAD), and more broadly, CD is often interpreted as evidence of spin-orbit coupling. Meanwhile, it is well-established that CD originates from the photoemission matrix elements, which can have extrinsic contributions related to the experimental geometry and the inherently broken inversion symmetry at the sample surface. Therefore, it is important to broadly examine CD-ARPES to determine the scenarios in which it provides a robust probe of intrinsic material physics. We performed CD-ARPES on the canonical topological insulator $\mathrm{Bi}_2\mathrm{Se}_3$ over a wide range of incident photon energies. Not only do we observe angle-dependent CD in the surface states, as expected, but we also find CD of a similar magnitude in virtually all bulk bands. Since OAM is forbidden by inversion symmetry in the bulk, we conclude this originates from symmetry-breaking in the photoemission process. Comparison with theoretical calculations supports this view and suggests that $\textit{hidden}$ OAM - localized to atomic sites within each unit cell - contributes significantly. Additional effects, including inter-atomic interference and final-state resonances, are responsible for the rapid variation of the CDAD signal with photon energy.

FOS: Physical sciences↗
NASA NTRS2000

Evaluation of DVD-R for Archival Applications

For more than a decade, CD-ROM and CD-R have provided an unprecedented level of reliability, low cost and cross-platform compatibility to support federal data archiving and distribution efforts. However, it should be remembered that years of effort were required to achieve the standardization that has supported the growth of the CD industry. Incompatibilities in the interpretation of the ISO-9660 standard on different operating systems had to be dealt with, and the imprecise specifications in the Orange Book Part n and Part Hi led to incompatibilities between CD-R media and CD-R recorders. Some of these issues were presented by the authors at Optical Data Storage '95. The major current problem with the use of CD technology is the growing volume of digital data that needs to be stored. CD-ROM collections of hundreds of volumes and CD-R collections of several thousand volumes are becoming almost too cumbersome to be useful. The emergence of Digital Video Disks Recorder (DVD-R) technology promises to reduce the number of discs required for archive applications by a factor of seven while providing improved reliability. It is important to identify problem areas for DVD-R media and provide guidelines to manufacturers, file system developers and users in order to provide reliable data storage and interchange. The Data Distribution Laboratory (DDL) at NASA's Jet Propulsion Laboratory began its evaluation of DVD-R technology in early 1998. The initial plan was to obtain a DVD-Recorder for preliminary testing, deploy reader hardware to user sites for compatibility testing, evaluate the quality and longevity of DVD-R media and develop proof-of-concept archive collections to test the reliability and usability of DVD-R media and jukebox hardware.

Martin, Michael D.↗
DOE OSTI2020

Materials Data on CeCdAu by Materials Project

CeAuCd crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Ce is bonded in a 11-coordinate geometry to five Au and six equivalent Cd atoms. There are four shorter (3.15 Å) and one longer (3.22 Å) Ce–Au bond lengths. There are two shorter (3.35 Å) and four longer (3.48 Å) Ce–Cd bond lengths. There are two inequivalent Au sites. In the first Au site, Au is bonded in a 9-coordinate geometry to three equivalent Ce and six equivalent Cd atoms. All Au–Cd bond lengths are 2.88 Å. In the second Au site, Au is bonded in a 9-coordinate geometry to six equivalent Ce and three equivalent Cd atoms. All Au–Cd bond lengths are 2.99 Å. Cd is bonded in a 4-coordinate geometry to six equivalent Ce and four Au atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on GdCdCu by Materials Project

GdCuCd crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. Gd is bonded in a 11-coordinate geometry to five Cu and six equivalent Cd atoms. There are four shorter (3.01 Å) and one longer (3.08 Å) Gd–Cu bond lengths. There are two shorter (3.22 Å) and four longer (3.34 Å) Gd–Cd bond lengths. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded in a 9-coordinate geometry to three equivalent Gd and six equivalent Cd atoms. All Cu–Cd bond lengths are 2.73 Å. In the second Cu site, Cu is bonded in a 9-coordinate geometry to six equivalent Gd and three equivalent Cd atoms. All Cu–Cd bond lengths are 2.86 Å. Cd is bonded in a 12-coordinate geometry to six equivalent Gd and four Cu atoms.

36 MATERIALS SCIENCE↗