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6 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Sr(AsPt)2 by Materials Project

SrPt2As2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Sr2+ is bonded in a 8-coordinate geometry to eight Pt2- atoms. There are a spread of Sr–Pt bond distances ranging from 3.20–3.58 Å. There are two inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in a 11-coordinate geometry to four equivalent Sr2+, three equivalent Pt2-, and four equivalent As1+ atoms. There are two shorter (2.99 Å) and one longer (3.01 Å) Pt–Pt bond lengths. There are a spread of Pt–As bond distances ranging from 2.52–2.74 Å. In the second Pt2- site, Pt2- is bonded in a 9-coordinate geometry to four equivalent Sr2+ and five As1+ atoms. There are a spread of Pt–As bond distances ranging from 2.54–2.58 Å. There are two inequivalent As1+ sites. In the first As1+ site, As1+ is bonded to four equivalent Pt2- atoms to form a mixture of corner and edge-sharing AsPt4 tetrahedra. In the second As1+ site, As1+ is bonded in a 5-coordinate geometry to five Pt2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu(AsPt)2 by Materials Project

EuPt2As2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Eu2+ is bonded in a 8-coordinate geometry to eight Pt2- atoms. There are four shorter (3.38 Å) and four longer (3.43 Å) Eu–Pt bond lengths. There are two inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in a 8-coordinate geometry to four equivalent Eu2+ and four equivalent As1+ atoms. All Pt–As bond lengths are 2.61 Å. In the second Pt2- site, Pt2- is bonded in a 5-coordinate geometry to four equivalent Eu2+ and five As1+ atoms. There are one shorter (2.49 Å) and four longer (2.55 Å) Pt–As bond lengths. There are two inequivalent As1+ sites. In the first As1+ site, As1+ is bonded to four equivalent Pt2- atoms to form a mixture of edge and corner-sharing AsPt4 tetrahedra. In the second As1+ site, As1+ is bonded in a 5-coordinate geometry to five Pt2- atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on AsPtS by Materials Project

PtAsS crystallizes in the cubic P2_13 space group. The structure is three-dimensional. Pt5+ is bonded to three equivalent As3- and three equivalent S2- atoms to form PtAs3S3 octahedra that share corners with twelve equivalent PtAs3S3 octahedra, corners with three equivalent AsPt3S tetrahedra, and corners with three equivalent SAsPt3 tetrahedra. The corner-sharing octahedra tilt angles range from 64–65°. All Pt–As bond lengths are 2.51 Å. All Pt–S bond lengths are 2.54 Å. As3- is bonded to three equivalent Pt5+ and one S2- atom to form distorted AsPt3S tetrahedra that share corners with three equivalent PtAs3S3 octahedra, corners with six equivalent AsPt3S tetrahedra, and corners with nine equivalent SAsPt3 tetrahedra. The corner-sharing octahedral tilt angles are 76°. The As–S bond length is 2.34 Å. S2- is bonded to three equivalent Pt5+ and one As3- atom to form SAsPt3 tetrahedra that share corners with three equivalent PtAs3S3 octahedra, corners with six equivalent SAsPt3 tetrahedra, and corners with nine equivalent AsPt3S tetrahedra. The corner-sharing octahedral tilt angles are 78°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Sr(AsPt)2 by Materials Project

SrPt2As2 crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. Sr2+ is bonded in a 8-coordinate geometry to eight Pt2- atoms. There are four shorter (3.39 Å) and four longer (3.46 Å) Sr–Pt bond lengths. There are two inequivalent Pt2- sites. In the first Pt2- site, Pt2- is bonded in a 8-coordinate geometry to four equivalent Sr2+ and four equivalent As1+ atoms. All Pt–As bond lengths are 2.61 Å. In the second Pt2- site, Pt2- is bonded in a 9-coordinate geometry to four equivalent Sr2+ and five As1+ atoms. There are one shorter (2.53 Å) and four longer (2.56 Å) Pt–As bond lengths. There are two inequivalent As1+ sites. In the first As1+ site, As1+ is bonded in a 5-coordinate geometry to five Pt2- atoms. In the second As1+ site, As1+ is bonded to four equivalent Pt2- atoms to form a mixture of distorted corner and edge-sharing AsPt4 tetrahedra.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Eu2(AsPt)3 by Materials Project

Eu2(PtAs)3 crystallizes in the tetragonal P4/mmm space group. The structure is one-dimensional and consists of one Eu2(PtAs)3 ribbon oriented in the (0, 0, 1) direction. Eu+2.50+ is bonded in a linear geometry to one Pt+1.33+ and one As3- atom. The Eu–Pt bond length is 2.62 Å. The Eu–As bond length is 2.91 Å. There are two inequivalent Pt+1.33+ sites. In the first Pt+1.33+ site, Pt+1.33+ is bonded in a linear geometry to one Eu+2.50+ and one As3- atom. The Pt–As bond length is 2.32 Å. In the second Pt+1.33+ site, Pt+1.33+ is bonded in a linear geometry to two equivalent As3- atoms. Both Pt–As bond lengths are 2.25 Å. There are two inequivalent As3- sites. In the first As3- site, As3- is bonded in a linear geometry to two equivalent Pt+1.33+ atoms. In the second As3- site, As3- is bonded in a linear geometry to one Eu+2.50+ and one Pt+1.33+ atom.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Regulation of L - and D -Aspartate Transport and Metabolism in Acinetobacter baylyi ADP1

Here, the regulated uptake and consumption of d-amino acids by bacteria remain largely unexplored, despite the physiological importance of these compounds. Unlike other characterized bacteria, such as Escherichia coli, which utilizes only l-Asp, Acinetobacter baylyi ADP1 can consume both d-Asp and l-Asp as the sole carbon or nitrogen source. As described here, two LysR-type transcriptional regulators (LTTRs), DarR and AalR, control d- and l-Asp metabolism in strain ADP1. Heterologous expression of A. baylyi proteins enabled E. coli to use d-Asp as the carbon source when either of two transporters (AspT or AspY) and a racemase (RacD) were coexpressed. A third transporter, designated AspS, was also discovered to transport Asp in ADP1. DarR and/or AalR controlled the transcription of aspT, aspY, racD, and aspA (which encodes aspartate ammonia lyase). Conserved residues in the N-terminal DNA-binding domains of both regulators likely enable them to recognize the same DNA consensus sequence (ATGC-N7-GCAT) in several operator-promoter regions. In strains lacking AalR, suppressor mutations revealed a role for the ClpAP protease in Asp metabolism. In the absence of the ClpA component of this protease, DarR can compensate for the loss of AalR. ADP1 consumed l- and d-Asn and l-Glu, but not d-Glu, as the sole carbon or nitrogen source using interrelated pathways.

59 BASIC BIOLOGICAL SCIENCES↗