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All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Materials Data on Ca(H8O5)2 by Materials Project

Ca2H30O19H2O crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of one water molecule and one Ca2H30O19 sheet oriented in the (0, 0, 1) direction. In the Ca2H30O19 sheet, there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.25–2.61 Å. In the second Ca site, Ca is bonded in a 8-coordinate geometry to one H and seven O atoms. The Ca–H bond length is 2.41 Å. There are a spread of Ca–O bond distances ranging from 2.34–2.77 Å. There are thirty inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.02 Å. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.55 Å) H–O bond length. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. In the sixth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.55 Å) H–O bond length. In the seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the eighth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.58 Å) H–O bond length. In the ninth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the tenth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.61 Å) H–O bond length. In the eleventh H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.65 Å) H–O bond length. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the fourteenth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.64 Å) H–O bond length. In the fifteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. In the sixteenth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.58 Å) H–O bond length. In the seventeenth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.10 Å) and one longer (1.41 Å) H–O bond length. In the eighteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the nineteenth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.00 Å) and one longer (1.64 Å) H–O bond length. In the twentieth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.55 Å) H–O bond length. In the twenty-first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the twenty-second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the twenty-third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the twenty-fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the twenty-fifth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.61 Å) H–O bond length. In the twenty-sixth H site, H is bonded in a single-bond geometry to one Ca and one O atom. The H–O bond length is 0.98 Å. In the twenty-seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the twenty-eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the twenty-ninth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the thirtieth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.62 Å) H–O bond length. There are nineteen inequivalent O sites. In the first O site, O is bonded in a 4-coordinate geometry to three H and one O atom. The O–O bond length is 1.49 Å. In the second O site, O is bonded in a distorted tetrahedral geometry to three H and one O atom. The O–O bond length is 1.48 Å. In the third O site, O is bonded in a single-bond geometry to one H and one O atom. In the fourth O site, O is bonded in a single-bond geometry to one H and one O atom. In the fifth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the sixth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the seventh O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the eighth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the ninth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the tenth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the eleventh O site, O is bonded in a distorted trigonal non-coplanar geometry to three H atoms. In the twelfth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the thirteenth O site, O is bonded in a 4-coordinate geometry to four H atoms. In the fourteenth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the fifteenth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the sixteenth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the seventeenth O site, O is bonded in a distorted single-bond geometry to one Ca and two H atoms. In the eighteenth O site, O is bonded in a distorted water-like geometry to one Ca and three H atoms. In the nineteenth O site, O is bonded in a water-like geometry to one Ca and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(H8O5)2 by Materials Project

Ca(H8O5)2 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of two Ca(H8O5)2 sheets oriented in the (0, 0, 1) direction. In one of the Ca(H8O5)2 sheets, Ca is bonded in a distorted pentagonal bipyramidal geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.36–2.57 Å. There are sixteen inequivalent H sites. In the first H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.66 Å) H–O bond length. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. In the fourth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.54 Å) H–O bond length. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the sixth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.61 Å) H–O bond length. In the seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the eighth H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.00 Å) and one longer (1.78 Å) H–O bond length. In the ninth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the tenth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.04 Å) and one longer (1.55 Å) H–O bond length. In the eleventh H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.63 Å) H–O bond length. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the thirteenth H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.71 Å) H–O bond length. In the fourteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fifteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the sixteenth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.67 Å) H–O bond length. There are ten inequivalent O sites. In the first O site, O is bonded in a 5-coordinate geometry to four H and one O atom. The O–O bond length is 1.50 Å. In the second O site, O is bonded in a 5-coordinate geometry to four H and one O atom. In the third O site, O is bonded in a distorted water-like geometry to two H atoms. In the fourth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the sixth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the seventh O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the eighth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the tenth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In one of the Ca(H8O5)2 sheets, Ca is bonded in a 8-coordinate geometry to seven O atoms. There are a spread of Ca–O bond distances ranging from 2.39–2.63 Å. There are sixteen inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the second H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.04 Å) and one longer (1.51 Å) H–O bond length. In the third H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.55 Å) H–O bond length. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the sixth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. In the eighth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.61 Å) H–O bond length. In the ninth H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.72 Å) H–O bond length. In the tenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the eleventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the twelfth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.04 Å) and one longer (1.55 Å) H–O bond length. In the thirteenth H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.70 Å) H–O bond length. In the fourteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fifteenth H site, H is bonded in a distorted single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the sixteenth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.64 Å) H–O bond length. There are ten inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to three H and one O atom. The O–O bond length is 1.49 Å. In the second O site, O is bonded in a 5-coordinate geometry to four H and one O atom. In the third O site, O is bonded in a distorted water-like geometry to two H atoms. In the fourth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the sixth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the seventh O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the eighth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the ninth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the tenth O site, O is bonded in a water-like geometry to one Ca and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Structural basis for the subtype-selectivity of K Ca 2.2 channel activators

Small-conductance (K Ca 2.2) and intermediate-conductance (K Ca 3.1) Ca 2+ -activated K + channels are gated by a Ca 2+ -calmodulin dependent mechanism. NS309 potentiates the activity of both K Ca 2.2 and K Ca 3.1, while rimtuzalcap selectively activates K Ca 2.2. Rimtuzalcap has been used in clinical trials for the treatment of spinocerebellar ataxia and essential tremor. We report cryo-electron microscopy structures of NS309-bound K Ca 2.2 and K Ca 3.1, in addition to structures of rimtuzalcap-bound K Ca 2.2 and mutant K Ca 3.1_R355K. The different conformations of calmodulin and the cytoplasmic HC helices in the two channels underlie the subtype-selectivity of rimtuzalcap for K Ca 2.2. NS309 binds to pre-existing pockets in both channels, while the bulkier rimtuzalcap binds in an induced-fit pocket in K Ca 2.2 requiring conformational changes. In K Ca 2.2, calmodulin’s N-lobes are sufficiently far apart to enable conformational changes to accommodate either NS309 or rimtuzalcap. In K Ca 3.1, calmodulin’s N-lobes are closer to each other and constrained by K Ca 3.1’s HC helices, which allows binding of NS309 but not rimtuzalcap. Replacement of arginine-355 in K Ca 3.1’s HB helix with lysine (K Ca 3.1_R355K) allows the binding of rimtuzalcap and renders the mutant channel sensitive to rimtuzalcap. These structures provide a framework for structure-based drug design targeting K Ca 2.2 channels.

Nam, Young-Woo [Chapman Univ., Irvine, CA (United ↗
DOE OSTI2020

Materials Data on Ca(H8O5)2 by Materials Project

(Ca2H29O18)2(H2O)2H2O2 crystallizes in the triclinic P1 space group. The structure is one-dimensional and consists of one water molecule; one water molecule; and one Ca2H29O18 ribbon oriented in the (0, 1, 0) direction. In the Ca2H29O18 ribbon, there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a 6-coordinate geometry to six O atoms. There are a spread of Ca–O bond distances ranging from 2.34–2.63 Å. In the second Ca site, Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.37–2.73 Å. There are twenty-nine inequivalent H sites. In the first H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.09 Å) and one longer (1.39 Å) H–O bond length. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the third H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.11 Å) and one longer (1.36 Å) H–O bond length. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the sixth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the ninth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the tenth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.10 Å) and one longer (1.37 Å) H–O bond length. In the eleventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the twelfth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.57 Å) H–O bond length. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the fourteenth H site, H is bonded in a distorted single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the fifteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the sixteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the seventeenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the eighteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the nineteenth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.04 Å) and one longer (1.51 Å) H–O bond length. In the twentieth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the twenty-first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the twenty-second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the twenty-third H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.05 Å) and one longer (1.54 Å) H–O bond length. In the twenty-fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the twenty-fifth H site, H is bonded in a distorted single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the twenty-sixth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the twenty-seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the twenty-eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the twenty-ninth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. There are eighteen inequivalent O sites. In the first O site, O is bonded in a tetrahedral geometry to four H atoms. In the second O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the third O site, O is bonded in a distorted single-bond geometry to one Ca and two H atoms. In the fourth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the sixth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the seventh O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the eighth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the tenth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the eleventh O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the twelfth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the thirteenth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the fourteenth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the fifteenth O site, O is bonded in a distorted single-bond geometry to one Ca and one H atom. In the sixteenth O site, O is bonded in a single-bond geometry to one H atom. In the seventeenth O site, O is bonded in a 3-coordinate geometry to two H and one O atom. The O–O bond length is 1.48 Å. In the eighteenth O site, O is bonded in a single-bond geometry to one H and one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(Al5Cr)2 by Materials Project

CaCr2Al10 is Bergman Structure: Mg32(Al,Zn)49 Bergman-like structured and crystallizes in the tetragonal P4/nmm space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a 12-coordinate geometry to four equivalent Cr and twelve Al atoms. All Ca–Cr bond lengths are 3.36 Å. There are four shorter (3.17 Å) and eight longer (3.31 Å) Ca–Al bond lengths. In the second Ca site, Ca is bonded in a 8-coordinate geometry to sixteen Al atoms. There are a spread of Ca–Al bond distances ranging from 3.18–3.33 Å. Cr is bonded in a 12-coordinate geometry to one Ca and ten Al atoms. There are a spread of Cr–Al bond distances ranging from 2.53–2.76 Å. There are ten inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Ca, two equivalent Cr, and seven Al atoms. There are a spread of Al–Al bond distances ranging from 2.76–2.92 Å. In the second Al site, Al is bonded in a 9-coordinate geometry to one Ca, two equivalent Cr, and seven Al atoms. There are a spread of Al–Al bond distances ranging from 2.58–3.10 Å. In the third Al site, Al is bonded in a 10-coordinate geometry to one Ca, two equivalent Cr, and seven Al atoms. Both Al–Cr bond lengths are 2.73 Å. There are a spread of Al–Al bond distances ranging from 2.76–2.92 Å. In the fourth Al site, Al is bonded in a 10-coordinate geometry to one Ca, two equivalent Cr, and seven Al atoms. There are a spread of Al–Al bond distances ranging from 2.81–2.92 Å. In the fifth Al site, Al is bonded in a 12-coordinate geometry to two equivalent Ca, two equivalent Cr, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.72–2.93 Å. In the sixth Al site, Al is bonded in a 12-coordinate geometry to two equivalent Ca, two equivalent Cr, and eight Al atoms. Both Al–Ca bond lengths are 3.31 Å. Both Al–Cr bond lengths are 2.53 Å. There are two shorter (2.72 Å) and two longer (2.93 Å) Al–Al bond lengths. In the seventh Al site, Al is bonded in a 12-coordinate geometry to two equivalent Ca, two equivalent Cr, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.72–2.93 Å. In the eighth Al site, Al is bonded in a 12-coordinate geometry to two equivalent Ca, two equivalent Cr, and eight Al atoms. Both Al–Cr bond lengths are 2.53 Å. There are a spread of Al–Al bond distances ranging from 2.72–2.93 Å. In the ninth Al site, Al is bonded in a 12-coordinate geometry to one Ca, two equivalent Cr, and eight Al atoms. Both Al–Al bond lengths are 2.64 Å. In the tenth Al site, Al is bonded in a 12-coordinate geometry to two equivalent Ca, two equivalent Cr, and eight Al atoms. Both Al–Al bond lengths are 2.81 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(BO3)2 by Materials Project

Ca(BO3)2 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.39–2.57 Å. In the second Ca site, Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.41–2.69 Å. There are four inequivalent B sites. In the first B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.43–1.47 Å. In the second B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.49 Å. In the third B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.44–1.53 Å. In the fourth B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There is three shorter (1.44 Å) and one longer (1.54 Å) B–O bond length. There are twelve inequivalent O sites. In the first O site, O is bonded in a distorted trigonal planar geometry to one Ca and two B atoms. In the second O site, O is bonded in a distorted single-bond geometry to two Ca and one B atom. In the third O site, O is bonded in a single-bond geometry to one B atom. In the fourth O site, O is bonded in a distorted single-bond geometry to one Ca and one B atom. In the fifth O site, O is bonded in a distorted single-bond geometry to one Ca and one B atom. In the sixth O site, O is bonded in a distorted single-bond geometry to two Ca and one B atom. In the seventh O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and one B atom. In the eighth O site, O is bonded in a distorted trigonal planar geometry to one Ca and two B atoms. In the ninth O site, O is bonded in a distorted bent 120 degrees geometry to two Ca and two B atoms. In the tenth O site, O is bonded in a 2-coordinate geometry to one Ca and two B atoms. In the eleventh O site, O is bonded in a distorted single-bond geometry to two Ca and one B atom. In the twelfth O site, O is bonded in a distorted single-bond geometry to two Ca and one B atom.

36 MATERIALS SCIENCE↗
NASA NTRS2000

Regulation of RYR1 activity by Ca(2+) and calmodulin

The skeletal muscle calcium release channel (RYR1) is a Ca(2+)-binding protein that is regulated by another Ca(2+)-binding protein, calmodulin. The functional consequences of calmodulin's interaction with RYR1 are dependent on Ca(2+) concentration. At nanomolar Ca(2+) concentrations, calmodulin is an activator, but at micromolar Ca(2+) concentrations, calmodulin is an inhibitor of RYR1. This raises the question of whether the Ca(2+)-dependent effects of calmodulin on RYR1 function are due to Ca(2+) binding to calmodulin, RYR1, or both. To distinguish the effects of Ca(2+) binding to calmodulin from those of Ca(2+) binding to RYR1, a mutant calmodulin that cannot bind Ca(2+) was used to evaluate the effects of Ca(2+)-free calmodulin on Ca(2+)-bound RYR1. We demonstrate that Ca(2+)-free calmodulin enhances the affinity of RYR1 for Ca(2+) while Ca(2+) binding to calmodulin converts calmodulin from an activator to an inhibitor. Furthermore, Ca(2+) binding to RYR1 enhances its affinity for both Ca(2+)-free and Ca(2+)-bound calmodulin.

Non-NASA Center↗
DOE OSTI2022

Selective posttranslational inhibition of Ca V β 1 -associated voltage-dependent calcium channels with a functionalized nanobody

Ca 2+ influx through high-voltage-activated calcium channels (HVACCs) controls diverse cellular functions. A critical feature enabling a singular signal, Ca 2+ influx, to mediate disparate functions is diversity of HVACC pore-forming α1 and auxiliary Ca V β 1 –Ca V β 4 subunits. Selective Ca V α 1 blockers have enabled deciphering their unique physiological roles. By contrast, the capacity to post-translationally inhibit HVACCs based on Ca V β isoform is non-existent. Conventional gene knockout/shRNA approaches do not adequately address this deficit owing to subunit reshuffling and partially overlapping functions of Ca V β isoforms. Here, we identify a nanobody (nb.E8) that selectively binds Ca V β 1 SH3 domain and inhibits Ca V β 1 -associated HVACCs by reducing channel surface density, decreasing open probability, and speeding inactivation. Functionalizing nb.E8 with Nedd4L HECT domain yielded Chisel-1 which eliminated current through Ca V β 1 -reconstituted Ca V 1/Ca V 2 and native Ca V 1.1 channels in skeletal muscle, strongly suppressed depolarization-evoked Ca 2+ influx and excitation-transcription coupling in hippocampal neurons, but was inert against Ca V β 2 -associated Ca V 1.2 in cardiomyocytes. The results introduce an original method for probing distinctive functions of ion channel auxiliary subunit isoforms, reveal additional dimensions of Ca V β 1 signaling in neurons, and describe a genetically-encoded HVACC inhibitor with unique properties.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2022

Ca-isotopes as a robust tracer of magmatic differentiation

The large mass difference (~10%) between the two most abundant isotopes of calcium, 40 Ca and 44 Ca, gives Ca great potential in tracking mass-dependent fractionation during magmatic processes. Resolvable Ca-isotope fractionation during fractional crystallization of magma, particularly by feldspar in evolved melts, has been theoretically inferred but not robustly tested in nature. To further explore the effects of magmatic differentiation on Ca-isotope systematics, we studied the late-Permian alkaline igneous suite of the Øyangen Caldera, Oslo Rift, Norway, consisting of volcanic and intrusive units ranging from basanitic to rhyolitic compositions. Major and trace element variations and modeling demonstrate that the main series of samples (N = 21), including basanites, ring-dyke syenites, and central-dome syenites, likely documents a co-genetic and closed-system fractional crystallization sequence. Our data show minimal δ 44/40 Ca variation (< 0.05 ‰) in the intermediate magma and a marked increase in δ 44/40 Ca in the felsic magma of the Øyangen Caldera (from 0.62 ± 0.02 ‰ to 1.15 ± 0.03 ‰ relative to Ca standard, SRM915a). The systematic increase is best explained by equilibrium isotopic fractionation dominated by alkali feldspar in the fractionating mineral assemblage. This is further supported by strong correlations between δ 44/40 Ca, CaO, and Eu/Eu* in the main-series samples. Implementing a Monte Carlo approach, isotopic modeling of the liquid line of descent using Rayleigh fractionation is highly consistent with the observed Ca-isotope evolution. For the first time, we confirm prominent Ca stable isotope fractionation in felsic-stage differentiation of alkaline magma and constrain the isotope fractionation factors of plagioclase and K-feldspar. Integrated with extant estimations on mineral fractionation factors from the literature, our results suggest increasing fractionation effects of rock-forming minerals with decreasing Ca content. Finally, the affirmation of significant Ca-isotope fractionation in alkaline magma by feldspar empowers the application of Ca as a versatile tracer of crustal evolution, allowing further tests in other magmatic conditions across various planetary objects.

58 GEOSCIENCES↗
DOE OSTI2022

Phase Stability and Kinetics of Topotactic Dual Ca 2+ –Na + Ion Electrochemistry in NaSICON NaV 2 (PO 4 ) 3

Recent reports of reversible calcium plating and stripping have rekindled interest in the development of Ca-ion batteries (CIBs) as next-generation energy storage devices. This technology has the potential to overcome the limitations of conventional Li-ion batteries, but CIBs are plagued by a paucity of suitable cathode materials. To date, NaSICON-structured NaV 2 (PO 4 ) 3 has been demonstrated as a successful cathode candidate, exhibiting reversible (de)intercalation of 0.6 mol Ca 2+ along with stable cycling performance. However, a complex multiphase mixture forms on discharge so the Ca-ion charge storage mechanism in the NaSICON framework is poorly understood. Here in this work, we report on an investigation of the structure and/or Na + /Ca 2+ environment(s) of a variety of chemically prepared NaSICON Ca x Na y V 2 (PO 4 ) 3 phases which were characterized using synchrotron XRD, SEM-EDS, 23 Na NMR, and TEM. Highly calciated CaV 2 (PO 4 ) 3 , Ca 1.5 V 2 (PO 4 ) 3 , and CaNaV 2 (PO 4 ) 3 phases can be prepared at high temperature, but -unlike Ca 0.6 NaV 2 (PO 4 ) 3 -these materials are electrochemically inactive. To better understand the fundamental factors impacting successful Ca 2+ electrochemistry in this system, DFT was employed to examine the Ca x Na y V 2 (PO 4 ) 3 phase diagram and Ca 2+ diffusion mechanism. Theoretical insights show that phase separation into Na-rich and Ca-rich phases is a reason for the capacity limitation and demonstrate that Na + ions in the host materials assist the migration of neighboring Ca 2+ ions, enabling reversible electrochemistry in Ca x Na y V 2 (PO 4 ) 3 . This investigation of fundamental principles affecting reversible Ca 2+ (de)intercalation in Ca x Na y V 2 (PO 4 ) 3 allows for the development of design principles to enable the discovery of a variety of successful cathodes for CIBs.

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

Materials Data on Ca(B2O5)3 by Materials Project

Ca(B2O5)3 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. Ca is bonded in a 10-coordinate geometry to ten O atoms. There are a spread of Ca–O bond distances ranging from 2.38–3.04 Å. There are six inequivalent B sites. In the first B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.36–1.40 Å. In the second B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.47–1.49 Å. In the third B site, B is bonded in a trigonal planar geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.35–1.41 Å. In the fourth B site, B is bonded to four O atoms to form corner-sharing BO4 tetrahedra. There are a spread of B–O bond distances ranging from 1.46–1.50 Å. In the fifth B site, B is bonded in a trigonal planar geometry to three O atoms. There is two shorter (1.37 Å) and one longer (1.39 Å) B–O bond length. In the sixth B site, B is bonded in a 1-coordinate geometry to three O atoms. There are a spread of B–O bond distances ranging from 1.28–1.43 Å. There are fifteen inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to one Ca and two B atoms. In the second O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and two B atoms. In the third O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and two B atoms. In the fourth O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and two B atoms. In the fifth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the sixth O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and two B atoms. In the seventh O site, O is bonded in a bent 120 degrees geometry to one Ca and two B atoms. In the eighth O site, O is bonded in a bent 120 degrees geometry to two B atoms. In the ninth O site, O is bonded in a single-bond geometry to one B atom. In the tenth O site, O is bonded in a distorted single-bond geometry to one Ca and one B atom. In the eleventh O site, O is bonded in a single-bond geometry to one Ca and one B atom. In the twelfth O site, O is bonded in a distorted linear geometry to one Ca and one B atom. In the thirteenth O site, O is bonded in a water-like geometry to one Ca and one O atom. The O–O bond length is 1.31 Å. In the fourteenth O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.28 Å. In the fifteenth O site, O is bonded in a bent 120 degrees geometry to two O atoms.

36 MATERIALS SCIENCE↗
NASA NTRS2000

Skeletal muscle Ca(2+)-independent kinase activity increases during either hypertrophy or running

Spikes in free Ca(2+) initiate contractions in skeletal muscle cells, but whether and how they might signal to transcription factors in skeletal muscles of living animals is unknown. Since previous studies in non-muscle cells have shown that serum response factor (SRF) protein, a transcription factor, is phosphorylated rapidly by Ca(2+)/calmodulin (CaM)-dependent protein kinase after rises in intracellular Ca(2+), we measured enzymatic activity that phosphorylates SRF (designated SRF kinase activity). Homogenates from 7-day-hypertrophied anterior latissimus dorsi muscles of roosters had more Ca(2+)-independent SRF kinase activity than their respective control muscles. However, no differences were noted in Ca(2+)/CaM-dependent SRF kinase activity between control and trained muscles. To determine whether the Ca(2+)-independent and Ca(2+)/CaM-dependent forms of Ca(2+)/CaM-dependent protein kinase II (CaMKII) might contribute to some of the SRF kinase activity, autocamtide-3, a synthetic substrate that is specific for CaMKII, was employed. While the Ca(2+)-independent form of CaMKII was increased, like the Ca(2+)-independent form of SRF kinase, no alteration in CaMKII occurred at 7 days of stretch overload. These observations suggest that some of SRF phosphorylation by skeletal muscle extracts could be due to CaMKII. To determine whether this adaptation was specific to the exercise type (i.e., hypertrophy), similar measurements were made in the white vastus lateralis muscle of rats that had completed 2 wk of voluntary running. Although Ca(2+)-independent SRF kinase was increased, no alteration occurred in Ca(2+)/CaM-dependent SRF kinase activity. Thus any role of Ca(2+)-independent SRF kinase signaling has downstream modulators specific to the exercise phenotype.

NASA Program Fundamental Space Biology↗
DOE OSTI2020

Materials Data on Ca(H8O5)2 by Materials Project

Ca(H8O5)2 crystallizes in the monoclinic Pc space group. The structure is two-dimensional and consists of two Ca(H8O5)2 sheets oriented in the (0, 0, 1) direction. Ca is bonded in a body-centered cubic geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.46–2.55 Å. There are sixteen inequivalent H sites. In the first H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.65 Å) H–O bond length. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the fourth H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.70 Å) H–O bond length. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the sixth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.61 Å) H–O bond length. In the seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the eighth H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.00 Å) and one longer (1.74 Å) H–O bond length. In the ninth H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.73 Å) H–O bond length. In the tenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the eleventh H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.62 Å) H–O bond length. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the thirteenth H site, H is bonded in a single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.71 Å) H–O bond length. In the fourteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fifteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. In the sixteenth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.63 Å) H–O bond length. There are ten inequivalent O sites. In the first O site, O is bonded in a 5-coordinate geometry to four H and one O atom. The O–O bond length is 1.51 Å. In the second O site, O is bonded in a 2-coordinate geometry to four H and one O atom. In the third O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the fourth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the fifth O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and two H atoms. In the sixth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the seventh O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the eighth O site, O is bonded in a distorted bent 120 degrees geometry to one Ca and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the tenth O site, O is bonded in a water-like geometry to one Ca and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(H8O5)2 by Materials Project

Ca(H8O5)2 crystallizes in the monoclinic Pc space group. The structure is two-dimensional and consists of two Ca(H8O5)2 sheets oriented in the (0, 0, 1) direction. Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.49–2.55 Å. There are sixteen inequivalent H sites. In the first H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.63 Å) H–O bond length. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the third H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.62 Å) H–O bond length. In the fourth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the sixth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.63 Å) H–O bond length. In the seventh H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.67 Å) H–O bond length. In the eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.01 Å. In the ninth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the tenth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.61 Å) H–O bond length. In the eleventh H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.63 Å) H–O bond length. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fourteenth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.61 Å) H–O bond length. In the fifteenth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.63 Å) H–O bond length. In the sixteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. There are ten inequivalent O sites. In the first O site, O is bonded in a 5-coordinate geometry to four H and one O atom. The O–O bond length is 1.49 Å. In the second O site, O is bonded in a 5-coordinate geometry to four H and one O atom. In the third O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the fourth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the sixth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the seventh O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the eighth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the tenth O site, O is bonded in a water-like geometry to one Ca and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(H8O5)2 by Materials Project

Ca(H8O5)2 crystallizes in the monoclinic Cc space group. The structure is two-dimensional and consists of two Ca(H8O5)2 sheets oriented in the (0, 0, 1) direction. Ca is bonded in a 8-coordinate geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.47–2.58 Å. There are sixteen inequivalent H sites. In the first H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.66 Å) H–O bond length. In the second H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fourth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.64 Å) H–O bond length. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the sixth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.64 Å) H–O bond length. In the seventh H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.65 Å) H–O bond length. In the eighth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the ninth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.67 Å) H–O bond length. In the tenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the eleventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the twelfth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.62 Å) H–O bond length. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fourteenth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.60 Å) H–O bond length. In the fifteenth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.62 Å) H–O bond length. In the sixteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. There are ten inequivalent O sites. In the first O site, O is bonded in a 5-coordinate geometry to four H and one O atom. The O–O bond length is 1.49 Å. In the second O site, O is bonded in a 5-coordinate geometry to four H and one O atom. In the third O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the fourth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the sixth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the seventh O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the eighth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the tenth O site, O is bonded in a water-like geometry to one Ca and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca(H8O5)2 by Materials Project

Ca(H8O5)2 crystallizes in the triclinic P1 space group. The structure is two-dimensional and consists of two Ca(H8O5)2 sheets oriented in the (0, 0, 1) direction. Ca is bonded in a distorted body-centered cubic geometry to eight O atoms. There are a spread of Ca–O bond distances ranging from 2.45–2.79 Å. There are sixteen inequivalent H sites. In the first H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the second H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.58 Å) H–O bond length. In the third H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the fourth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.66 Å) H–O bond length. In the fifth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.98 Å. In the sixth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.03 Å) and one longer (1.56 Å) H–O bond length. In the seventh H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.97 Å. In the eighth H site, H is bonded in a linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.58 Å) H–O bond length. In the ninth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the tenth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.66 Å) H–O bond length. In the eleventh H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.69 Å) H–O bond length. In the twelfth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the thirteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 1.00 Å. In the fourteenth H site, H is bonded in a distorted linear geometry to two O atoms. There is one shorter (1.02 Å) and one longer (1.61 Å) H–O bond length. In the fifteenth H site, H is bonded in a distorted single-bond geometry to two O atoms. There is one shorter (1.01 Å) and one longer (1.66 Å) H–O bond length. In the sixteenth H site, H is bonded in a single-bond geometry to one O atom. The H–O bond length is 0.99 Å. There are ten inequivalent O sites. In the first O site, O is bonded in a 5-coordinate geometry to four H and one O atom. The O–O bond length is 1.49 Å. In the second O site, O is bonded in a 5-coordinate geometry to four H and one O atom. In the third O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the fourth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the fifth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the sixth O site, O is bonded in a distorted water-like geometry to one Ca and two H atoms. In the seventh O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the eighth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the ninth O site, O is bonded in a water-like geometry to one Ca and two H atoms. In the tenth O site, O is bonded in a water-like geometry to one Ca and two H atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Ca by Materials Project

Ca is alpha La structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are two inequivalent Ca sites. In the first Ca site, Ca is bonded to twelve Ca atoms to form a mixture of edge, corner, and face-sharing CaCa12 cuboctahedra. There are six shorter (3.89 Å) and six longer (3.91 Å) Ca–Ca bond lengths. In the second Ca site, Ca is bonded to twelve Ca atoms to form a mixture of edge, corner, and face-sharing CaCa12 cuboctahedra. All Ca–Ca bond lengths are 3.89 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2023

Association between soil organic carbon and calcium in acidic grassland soils from Point Reyes National Seashore, CA

Organo-mineral and organo-metal associations play an important role in the retention and accumulation of soil organic carbon (SOC). Recent studies have demonstrated a positive correlation between calcium (Ca) and SOC content in a range of soil types. However, most of these studies have focused on soils that contain calcium carbonate (pH > 6). To assess the importance of Ca-SOC associations in lower pH soils, we investigated their physical and chemical interaction in the grassland soils of Point Reyes National Seashore (CA, USA) at a range of spatial scales. Multivariate analyses of our bulk soil characterisation dataset showed a strong correlation between exchangeable Ca (Ca Exch ; 5–8.3 c.mol c kg –1 ) and SOC (0.6–4%) content. Additionally, linear combination fitting (LCF) of bulk Ca K-edge X-ray absorption near-edge structure (XANES) spectra revealed that Ca was predominantly associated with organic carbon across all samples. Scanning transmission X-ray microscopy near-edge X-ray absorption fine structure spectroscopy (STXM C/Ca NEXAFS) showed that Ca had a strong spatial correlation with C at the microscale. The STXM C NEXAFS K-edge spectra indicated that SOC had a higher abundance of aromatic/olefinic and phenolic C functional groups when associated with Ca, relative to C associated with Fe. In regions of high Ca-C association, the STXM C NEXAFS spectra were similar to the spectrum from lignin, with moderate changes in peak intensities and positions that are consistent with oxidative C transformation. Through this association, Ca thus seems to be preferentially associated with plant-like organic matter that has undergone some oxidative transformation, at depth in acidic grassland soils of California. Our study highlights the importance of Ca-SOC complexation in acidic grassland soils and provides a conceptual model of its contribution to SOC preservation, a research area that has previously been unexplored.

54 ENVIRONMENTAL SCIENCES↗