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Materials Data on B(HO)3 by Materials Project

H3BO3 is alpha Selenium structured and crystallizes in the trigonal P3_2 space group. The structure is zero-dimensional and consists of three H3BO3 clusters. there are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.67 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the third H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.67 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the fifth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. In the sixth H1+ site, H1+ is bonded in a distorted single-bond geometry to one O2- atom. The H–O bond length is 1.00 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms. In the second O2- site, O2- is bonded in a 2-coordinate geometry to one B3+ and one H1+ atom. In the third O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one H1+ atom. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one H1+ atom. In the sixth O2- site, O2- is bonded in a distorted bent 120 degrees geometry to one B3+ and one H1+ atom.

36 MATERIALS SCIENCE↗

Materials Data on B(HO)3 by Materials Project

H3BO3 crystallizes in the triclinic P-1 space group. The structure is two-dimensional and consists of two H3BO3 sheets oriented in the (1, 0, 0) direction. there are two inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.38 Å. There are six inequivalent H1+ sites. In the first H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.65 Å) H–O bond length. In the second H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.65 Å) H–O bond length. In the third H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.65 Å) H–O bond length. In the fourth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.65 Å) H–O bond length. In the fifth H1+ site, H1+ is bonded in a distorted single-bond geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.65 Å) H–O bond length. In the sixth H1+ site, H1+ is bonded in a distorted linear geometry to two O2- atoms. There is one shorter (1.00 Å) and one longer (1.65 Å) H–O bond length. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms. In the second O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms. In the third O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms. In the fourth O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms. In the fifth O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms. In the sixth O2- site, O2- is bonded in a distorted trigonal planar geometry to one B3+ and two H1+ atoms.

36 MATERIALS SCIENCE↗

Materials Data on Ho2B4C by Materials Project

Ho2B4C crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Ho is bonded in a 2-coordinate geometry to six equivalent B and two equivalent C atoms. There are four shorter (2.72 Å) and two longer (2.97 Å) Ho–B bond lengths. Both Ho–C bond lengths are 2.40 Å. There are two inequivalent B sites. In the first B site, B is bonded in a 3-coordinate geometry to six equivalent Ho and three B atoms. There is one shorter (1.77 Å) and two longer (1.87 Å) B–B bond length. In the second B site, B is bonded in a distorted single-bond geometry to two equivalent B and one C atom. The B–C bond length is 1.50 Å. C is bonded to four equivalent Ho and two equivalent B atoms to form distorted edge-sharing CHo4B2 octahedra.

36 MATERIALS SCIENCE↗

Materials Data on Ho5(SiB4)2 by Materials Project

Ho5Si2B8 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. there are two inequivalent Ho sites. In the first Ho site, Ho is bonded in a 12-coordinate geometry to nine B and three equivalent Si atoms. There are a spread of Ho–B bond distances ranging from 2.62–2.95 Å. There are one shorter (3.04 Å) and two longer (3.11 Å) Ho–Si bond lengths. In the second Ho site, Ho is bonded to two equivalent B and four equivalent Si atoms to form corner-sharing HoSi4B2 octahedra. The corner-sharing octahedral tilt angles are 57°. Both Ho–B bond lengths are 2.71 Å. All Ho–Si bond lengths are 2.89 Å. There are three inequivalent B sites. In the first B site, B is bonded in a 9-coordinate geometry to four equivalent Ho and five B atoms. There are a spread of B–B bond distances ranging from 1.75–1.83 Å. In the second B site, B is bonded in a 3-coordinate geometry to six equivalent Ho and three B atoms. The B–B bond length is 1.83 Å. In the third B site, B is bonded in a 9-coordinate geometry to five Ho and four equivalent B atoms. Si is bonded in a 9-coordinate geometry to eight Ho and one Si atom. The Si–Si bond length is 2.35 Å.

36 MATERIALS SCIENCE↗

Materials Data on Ho4NiB14 by Materials Project

Ho4NiB14 crystallizes in the tetragonal P4/mnc space group. The structure is three-dimensional. Ho is bonded in a 10-coordinate geometry to one Ni and sixteen B atoms. The Ho–Ni bond length is 2.77 Å. There are a spread of Ho–B bond distances ranging from 2.65–3.00 Å. Ni is bonded in a cuboctahedral geometry to four equivalent Ho and eight equivalent B atoms. All Ni–B bond lengths are 2.16 Å. There are three inequivalent B sites. In the first B site, B is bonded in a 9-coordinate geometry to four equivalent Ho and five B atoms. There is one shorter (1.66 Å) and four longer (1.74 Å) B–B bond length. In the second B site, B is bonded in a 9-coordinate geometry to four equivalent Ho, one Ni, and four B atoms. There is one shorter (1.74 Å) and two longer (1.83 Å) B–B bond length. In the third B site, B is bonded in a 3-coordinate geometry to six equivalent Ho and three B atoms. The B–B bond length is 1.82 Å.

36 MATERIALS SCIENCE↗

Theoretical branching ratios for the 5I7 to 5I7 levels of Ho(3+) in the garnets A3B2C3O12 (A = Y,La,Lu,Gd; B = Al,Lu,Sc,Ga; C = Al,Ga)

Results are reported from an experimental study investigating triply ionized holmium in 10 garnets using the point-change model to predict theoretical energy levels and temperature-dependent branching ratios for the 5I7 to 5I8 manifolds for temperatures between 50 and 400 K. Plots were made for the largest lines at 300 K. YScAG was plotted twice, once for each set of X-ray data available. Energy levels are predicted based on theoretical crystal-field parameters, and good agreement to experiment is found. It is suggested that the present set of theoretical crystal-field parameters provides good estimates of the energy levels for the other hosts on which there are no experimental optical data. X-ray and index-of-refraction data are used to evaluate the performance of 10 lasers via a quantum mechanical model to predict the position of the energy levels and the temperature-dependent branching rations of the 5I7 to 5I8 levels of holmium. The fractional population inversion required for threshold is also evaluated.

Filer, Elizabeth D.↗

Materials Data on Ho(BC)2 by Materials Project

HoB2C2 crystallizes in the tetragonal P4/mbm space group. The structure is three-dimensional. Ho is bonded in a 8-coordinate geometry to eight equivalent B and eight equivalent C atoms. All Ho–B bond lengths are 2.73 Å. All Ho–C bond lengths are 2.67 Å. B is bonded in a distorted trigonal planar geometry to four equivalent Ho and three equivalent C atoms. There is one shorter (1.52 Å) and two longer (1.60 Å) B–C bond length. C is bonded in a 3-coordinate geometry to four equivalent Ho and three equivalent B atoms.

36 MATERIALS SCIENCE↗

Measurement of atmospheric HO by a chemical method

The parameters for a chemical technique can be outlined from the following set of desirable goals: (1) sufficient conversion of tracer species A to product B that B can be measured quantitatively in the presence of A and a great excess of air; (2) specificity of reaction such that A is converted to B only by reaction with HO; and (3) sufficient sensitivity for detection that the ambient concentration of HO is not seriously perturbed by the presence of A and B. This proposed study involves finding a chemical reaction specific enough for OH, and a measurement of the product formed. What one wants is a rate constant of about 10 to the -10th power cu cm/s, so that 0.1 percent of the OH will be converted in 100 s. Laboratory studies are needed to find a reaction which will fill this bill, yielding a product in quantity sufficient for precise measurement. This is an extremely fast constant and the search may be difficult. Again there is a question of perturbing the local environment, while still providing a sensitive measurement. Also the temperature and pressure dependence of the reaction rate is a complicated function for many of these species (that is, one must use a RRKM or Troe-based picture), and must be taken into account.

Iyer, R. Subramonia↗

Tuning the melting point and phase stability of rare-earth oxides to facilitate their crystal growth from the melt

The challenge of growing rare-earth (RE) sesquioxide crystals can be overcome by tailoring their structural stability and melting point via composition engineering. This work contributes to the advancement of the field of crystal growth of high-entropy oxides. A compound with only small REs (Lu,Y,Ho,Yb,Er) 2 O 3 maintains a cubic C-type structure upon cooling from the melt, as observed via in-situ high-temperature neutron diffraction on aerodynamically levitated samples. On the other hand, a compound with a mixture of small and large REs (Lu,Y,Ho,Nd,La) 2 O 3 crystallizes as a mixture of a primary C-type phase with an unstable secondary phase. Crystals of compositions (Lu,Y,Ho,Nd,La) 2 O 3 and (Lu,Y,Gd,Nd,La) 2 O 3 were grown by the micro-pulling-down (mPD) method with a single monoclinic B-type phase, while a powder of (Lu,Y,Ho,Yb,Er) 2 O 3 did not melt at the maximum operating temperature of an iridium-rhenium crucible. The minimization of the melting point of the two grown crystals is attributed to the mismatch in cation sizes. The electron probe microanalysis reveals that the general element segregation behavior in the crystals depends on the composition.

36 MATERIALS SCIENCE↗

Materials Data on Ba3Ho(BO3)3 by Materials Project

Ba3Ho(BO3)3 crystallizes in the hexagonal P6_3cm space group. The structure is three-dimensional. there are four inequivalent Ba2+ sites. In the first Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.75–2.96 Å. In the second Ba2+ site, Ba2+ is bonded in a 9-coordinate geometry to nine O2- atoms. There are a spread of Ba–O bond distances ranging from 2.68–2.99 Å. In the third Ba2+ site, Ba2+ is bonded in a distorted q6 geometry to nine O2- atoms. There are six shorter (2.80 Å) and three longer (3.05 Å) Ba–O bond lengths. In the fourth Ba2+ site, Ba2+ is bonded in a distorted q6 geometry to nine O2- atoms. There are six shorter (2.81 Å) and three longer (2.95 Å) Ba–O bond lengths. There are two inequivalent Ho3+ sites. In the first Ho3+ site, Ho3+ is bonded in an octahedral geometry to six O2- atoms. There are three shorter (2.23 Å) and three longer (2.28 Å) Ho–O bond lengths. In the second Ho3+ site, Ho3+ is bonded in an octahedral geometry to six O2- atoms. All Ho–O bond lengths are 2.25 Å. There are three inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.39 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is two shorter (1.39 Å) and one longer (1.40 Å) B–O bond length. In the third B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. All B–O bond lengths are 1.40 Å. There are six inequivalent O2- sites. In the first O2- site, O2- is bonded in a distorted single-bond geometry to four Ba2+ and one B3+ atom. In the second O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Ho3+, and one B3+ atom. In the third O2- site, O2- is bonded in a 2-coordinate geometry to two equivalent Ba2+, one Ho3+, and one B3+ atom. In the fourth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+, one Ho3+, and one B3+ atom. In the fifth O2- site, O2- is bonded in a 1-coordinate geometry to three Ba2+, one Ho3+, and one B3+ atom. In the sixth O2- site, O2- is bonded in a distorted single-bond geometry to four Ba2+ and one B3+ atom.

36 MATERIALS SCIENCE↗

Materials Data on Li6Ho(BO3)3 by Materials Project

Li6Ho(BO3)3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are six inequivalent Li1+ sites. In the first Li1+ site, Li1+ is bonded to four O2- atoms to form distorted LiO4 tetrahedra that share a cornercorner with one HoO8 hexagonal bipyramid, a cornercorner with one LiO4 tetrahedra, corners with three LiO5 trigonal bipyramids, and an edgeedge with one LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.91–2.12 Å. In the second Li1+ site, Li1+ is bonded to five O2- atoms to form LiO5 trigonal bipyramids that share a cornercorner with one HoO8 hexagonal bipyramid, a cornercorner with one LiO4 tetrahedra, corners with two equivalent LiO5 trigonal bipyramids, edges with two equivalent HoO8 hexagonal bipyramids, and edges with two equivalent LiO5 trigonal bipyramids. There are a spread of Li–O bond distances ranging from 2.00–2.16 Å. In the third Li1+ site, Li1+ is bonded in a 5-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.92–2.54 Å. In the fourth Li1+ site, Li1+ is bonded to five O2- atoms to form distorted LiO5 trigonal bipyramids that share a cornercorner with one HoO8 hexagonal bipyramid, corners with two equivalent LiO4 tetrahedra, corners with two equivalent LiO5 trigonal bipyramids, edges with two equivalent HoO8 hexagonal bipyramids, and edges with two equivalent LiO5 trigonal bipyramids. There are a spread of Li–O bond distances ranging from 1.97–2.31 Å. In the fifth Li1+ site, Li1+ is bonded in a 3-coordinate geometry to five O2- atoms. There are a spread of Li–O bond distances ranging from 1.95–2.41 Å. In the sixth Li1+ site, Li1+ is bonded to four O2- atoms to form LiO4 tetrahedra that share a cornercorner with one HoO8 hexagonal bipyramid, a cornercorner with one LiO4 tetrahedra, an edgeedge with one HoO8 hexagonal bipyramid, and an edgeedge with one LiO4 tetrahedra. There are a spread of Li–O bond distances ranging from 1.87–1.97 Å. Ho3+ is bonded to eight O2- atoms to form distorted HoO8 hexagonal bipyramids that share corners with two LiO4 tetrahedra, corners with two LiO5 trigonal bipyramids, edges with two equivalent HoO8 hexagonal bipyramids, an edgeedge with one LiO4 tetrahedra, and edges with four LiO5 trigonal bipyramids. There are a spread of Ho–O bond distances ranging from 2.30–2.53 Å. There are three inequivalent B3+ sites. In the first B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.36–1.40 Å. In the second B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There is one shorter (1.38 Å) and two longer (1.39 Å) B–O bond length. In the third B3+ site, B3+ is bonded in a trigonal planar geometry to three O2- atoms. There are a spread of B–O bond distances ranging from 1.37–1.40 Å. There are nine inequivalent O2- sites. In the first O2- site, O2- is bonded in a 5-coordinate geometry to four Li1+ and one B3+ atom. In the second O2- site, O2- is bonded to three Li1+, one Ho3+, and one B3+ atom to form a mixture of distorted corner and edge-sharing OLi3HoB trigonal bipyramids. In the third O2- site, O2- is bonded in a 6-coordinate geometry to four Li1+, one Ho3+, and one B3+ atom. In the fourth O2- site, O2- is bonded in a 5-coordinate geometry to three Li1+, one Ho3+, and one B3+ atom. In the fifth O2- site, O2- is bonded to three Li1+, one Ho3+, and one B3+ atom to form a mixture of distorted corner and edge-sharing OLi3HoB trigonal bipyramids. In the sixth O2- site, O2- is bonded in a 4-coordinate geometry to one Li1+, two equivalent Ho3+, and one B3+ atom. In the seventh O2- site, O2- is bonded in a 5-coordinate geometry to four Li1+ and one B3+ atom. In the eighth O2- site, O2- is bonded to four Li1+ and one B3+ atom to form distorted edge-sharing OLi4B trigonal bipyramids. In the ninth O2- site, O2- is bonded in a 1-coordinate geometry to two Li1+, two equivalent Ho3+, and one B3+ atom.

36 MATERIALS SCIENCE↗

Mechanism of mixed-linkage glucan biosynthesis by barley cellulose synthase–like CslF6 (1,3;1,4)-β-glucan synthase

Mixed-linkage (1,3;1,4)-β-glucans, which are widely distributed in cell walls of the grasses, are linear glucose polymers containing predominantly (1,4)-β-linked glucosyl units interspersed with single (1,3)-β-linked glucosyl units. Their distribution in cereal grains and unique structures are important determinants of dietary fibers that are beneficial to human health. We demonstrate that the barley cellulose synthase-like CslF6 enzyme is sufficient to synthesize a high–molecular weight (1,3;1,4)-β-glucan in vitro. Biochemical and cryo–electron microscopy analyses suggest that CslF6 functions as a monomer. A conserved “switch motif” at the entrance of the enzyme’s transmembrane channel is critical to generate (1,3)-linkages. There, a single-point mutation markedly reduces (1,3)-linkage formation, resulting in the synthesis of cellulosic polysaccharides. Our results suggest that CslF6 monitors the orientation of the nascent polysaccharide’s second or third glucosyl unit. Register-dependent interactions with these glucosyl residues reposition the polymer’s terminal glucosyl unit to form either a (1,3)- or (1,4)-β-linkage.

59 BASIC BIOLOGICAL SCIENCES↗

Phylogenetics-based identification and characterization of a superior 2,3-butanediol dehydrogenase for Zymomonas mobilis expression

Abstract Background Zymomonas mobilis has recently been shown to be capable of producing the valuable platform biochemical, 2,3-butanediol (2,3-BDO). Despite this capability, the production of high titers of 2,3-BDO is restricted by several physiological parameters. One such bottleneck involves the conversion of acetoin to 2,3-BDO, a step catalyzed by 2,3-butanediol dehydrogenase (Bdh). Several Bdh enzymes have been successfully expressed in Z. mobilis, although a highly active enzyme is yet to be identified for expression in this host. Here, we report the application of a phylogenetic approach to identify and characterize a superior Bdh, followed by validation of its structural attributes using a mutagenesis approach. Results Of the 11 distinct bdh genes that were expressed in Z. mobilis, crude extracts expressing Serratia marcescens Bdh ( Sm Bdh) were found to have the highest activity (8.89 µmol/min/mg), when compared to other Bdh enzymes (0.34–2.87 µmol/min/mg). The Sm Bdh crystal structure was determined through crystallization with cofactor (NAD + ) and substrate (acetoin) molecules bound in the active site. Active Sm Bdh was shown to be a tetramer with the active site populated by a Gln247 residue contributed by the diagonally opposite subunit. Sm Bdh showed a more extensive supporting hydrogen-bond network in comparison to the other well-studied Bdh enzymes, which enables improved substrate positioning and substrate specificity. This protein also contains a short α6 helix, which provides more efficient entry and exit of molecules from the active site, thereby contributing to enhanced substrate turnover. Extending the α6 helix to mimic the lower activity Enterobacter cloacae ( Ec Bdh) enzyme resulted in reduction of Sm Bdh function to nearly 3% of the total activity. In great contrast, reduction of the corresponding α6 helix of the Ec Bdh to mimic the Sm Bdh structure resulted in ~ 70% increase in its activity. Conclusions This study has demonstrated that Sm Bdh is superior to other Bdhs for expression in Z. mobilis for 2,3-BDO production. Sm Bdh possesses unique structural features that confer biochemical advantage to this protein. While coordinated active site formation is a unique structural characteristic of this tetrameric complex, the smaller α6 helix and extended hydrogen network contribute towards improved activity and substrate promiscuity of the enzyme.

09 BIOMASS FUELS↗

Geometry of the charge density wave in the kagome metal A V 3 Sb 5

Kagome lattice is a fertile platform for topological and intertwined electronic excitations. Recently, experimental evidence of an unconventional charge density wave (CDW) is observed in a Z 2 kagome metal AV 3 Sb 5 (A=K, Cs, Rb). This observation triggers wide interest in the interplay between frustrated crystal structure and Fermi surface instabilities. Here, we analyze the lattice effect and its impact on CDW in AV 3 Sb 5 . Based on published experimental data, we show that the 2×2×2 CDW breaks the sixfold rotational symmetry of the crystal due to the phase shift between kagome layers and can explain the twofold symmetric CDW peak intensity observed by scanning tunneling spectroscopy. The coupling between the lattice and electronic degrees of freedom yields a weak first-order structural transition without continuous change of lattice dynamics. Our result emphasizes the fundamental role of lattice geometry in proper understanding of unconventional electronic orders in AV 3 Sb 5 .

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

Muon spin rotation and relaxation in Pr 1 - x Nd x Os 4 Sb 12 : Superconductivity and magnetism in Pr-rich alloys

The Pr-rich end 0 ≤ x ≤ 0.25 of the alloy series Pr 1-x Nd x ⁢Os 4 ⁢Sb 12 has been studied using muon spin rotation and relaxation. The end compound PrOs 4 ⁢Sb 12 is an unconventional heavy-fermion superconductor, which exhibits a spontaneous magnetic field associated with broken time-reversal symmetry (TRS) in the superconducting phase. Further, no such field is observed in the Nd-doped alloys for x ≥ 0.05, indicating that TRS has been restored. The superfluid density from the vortex-lattice field distribution is insensitive to Nd concentration for x ≲ 0.2, indicating that TRS restoration does not have a strong effect on the superconducting state. No Nd 3+ static magnetism, ordered or disordered, is found down to the lowest temperatures of measurement.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗