xi The ABC toxin complex from Yersinia entomophaga can package three different cytotoxic components expressed from distinct genetic loci in an unfolded state: the structures of both shell and cargo By journals.iucr.org Published On :: 2024-05-01 Bacterial ABC toxin complexes (Tcs) comprise three core proteins: TcA, TcB and TcC. The TcA protein forms a pentameric assembly that attaches to the surface of target cells and penetrates the cell membrane. The TcB and TcC proteins assemble as a heterodimeric TcB–TcC subcomplex that makes a hollow shell. This TcB–TcC subcomplex self-cleaves and encapsulates within the shell a cytotoxic `cargo' encoded by the C-terminal region of the TcC protein. Here, we describe the structure of a previously uncharacterized TcC protein from Yersinia entomophaga, encoded by a gene at a distant genomic location from the genes encoding the rest of the toxin complex, in complex with the TcB protein. When encapsulated within the TcB–TcC shell, the C-terminal toxin adopts an unfolded and disordered state, with limited areas of local order stabilized by the chaperone-like inner surface of the shell. We also determined the structure of the toxin cargo alone and show that when not encapsulated within the shell, it adopts an ADP-ribosyltransferase fold most similar to the catalytic domain of the SpvB toxin from Salmonella typhimurium. Our structural analysis points to a likely mechanism whereby the toxin acts directly on actin, modifying it in a way that prevents normal polymerization. Full Article text
xi Benchmarking predictive methods for small-angle X-ray scattering from atomic coordinates of proteins using maximum likelihood consensus data By journals.iucr.org Published On :: 2024-07-10 Stimulated by informal conversations at the XVII International Small Angle Scattering (SAS) conference (Traverse City, 2017), an international team of experts undertook a round-robin exercise to produce a large dataset from proteins under standard solution conditions. These data were used to generate consensus SAS profiles for xylose isomerase, urate oxidase, xylanase, lysozyme and ribonuclease A. Here, we apply a new protocol using maximum likelihood with a larger number of the contributed datasets to generate improved consensus profiles. We investigate the fits of these profiles to predicted profiles from atomic coordinates that incorporate different models to account for the contribution to the scattering of water molecules of hydration surrounding proteins in solution. Programs using an implicit, shell-type hydration layer generally optimize fits to experimental data with the aid of two parameters that adjust the volume of the bulk solvent excluded by the protein and the contrast of the hydration layer. For these models, we found the error-weighted residual differences between the model and the experiment generally reflected the subsidiary maxima and minima in the consensus profiles that are determined by the size of the protein plus the hydration layer. By comparison, all-atom solute and solvent molecular dynamics (MD) simulations are without the benefit of adjustable parameters and, nonetheless, they yielded at least equally good fits with residual differences that are less reflective of the structure in the consensus profile. Further, where MD simulations accounted for the precise solvent composition of the experiment, specifically the inclusion of ions, the modelled radius of gyration values were significantly closer to the experiment. The power of adjustable parameters to mask real differences between a model and the structure present in solution is demonstrated by the results for the conformationally dynamic ribonuclease A and calculations with pseudo-experimental data. This study shows that, while methods invoking an implicit hydration layer have the unequivocal advantage of speed, care is needed to understand the influence of the adjustable parameters. All-atom solute and solvent MD simulations are slower but are less susceptible to false positives, and can account for thermal fluctuations in atomic positions, and more accurately represent the water molecules of hydration that contribute to the scattering profile. Full Article text
xi Unity gives strength: combining Bertaut's and Belov's concepts and the formalism of aperiodic crystals to solve magnetic structures of unprecedented complexity By journals.iucr.org Published On :: 2024-10-29 Full Article text
xi New ion radii for oxides and oxysalts, fluorides, chlorides and nitrides By journals.iucr.org Published On :: 2024-07-15 Ion radii are derived here from the characteristic (grand mean) bond lengths for (i) 135 ions bonded to oxygen in 459 configurations (on the basis of coordination number) using 177 143 bond lengths extracted from 30 805 ordered coordination polyhedra from 9210 crystal structures; and (ii) 76 ions bonded to nitrogen in 137 configurations using 4048 bond lengths extracted from 875 ordered coordination polyhedra from 434 crystal structures. There are two broad categories of use for ion radii: (1) those methods which use the relative sizes of cation and anion radii to predict local atomic arrangements; (2) those methods which compare the radii of different cations (or the radii of different anions) to predict local atomic arrangements. There is much uncertainty with regard to the relative sizes of cations and anions, giving rise to the common failure of type (1) methods, e.g. Pauling's first rule which purports to relate the coordination adopted by cations to the radius ratio of the constituent cation and anion. Conversely, type (2) methods, which involve comparing the sizes of different cations with each other (or different anions with each other), can give very accurate predictions of site occupancies, physical properties etc. Methods belonging to type (2) can equally well use the characteristic bond lengths themselves (from which the radii are derived) in place of radii to develop correlations and predict crystal properties. Extensive quantum-mechanical calculations of electron density in crystals in the literature indicate that the radii of both cations and anions are quite variable with local arrangement, suggesting significant problems with any use of ion radii. However, the dichotomy between the experimentally derived ion radii and the quantum-mechanical calculations of electron density in crystals is removed by the recognition that ion radii are proxy variables for characteristic bond lengths in type (2) relations. Full Article text
xi Crystal structure of a water oxidation catalyst solvate with composition (NH4)2[FeIV(L-6H)]·3CH3COOH (L = clathrochelate ligand) By journals.iucr.org Published On :: 2024-01-01 The synthetic availability of molecular water oxidation catalysts containing high-valent ions of 3d metals in the active site is a prerequisite to enabling photo- and electrochemical water splitting on a large scale. Herein, the synthesis and crystal structure of diammonium {μ-1,3,4,7,8,10,12,13,16,17,19,22-dodecaazatetracyclo[8.8.4.13,17.18,12]tetracosane-5,6,14,15,20,21-hexaonato}ferrate(IV) acetic acid trisolvate, (NH4)2[FeIV(C12H12N12O6)]·3CH3COOH or (NH4)2[FeIV(L–6H)]·3CH3COOH is reported. The FeIV ion is encapsulated by the macropolycyclic ligand, which can be described as a dodeca-aza-quadricyclic cage with two capping triazacyclohexane fragments making three five- and six six-membered alternating chelate rings with the central FeIV ion. The local coordination environment of FeIV is formed by six deprotonated hydrazide nitrogen atoms, which stabilize the unusual oxidation state. The FeIV ion lies on a twofold rotation axis (multiplicity 4, Wyckoff letter e) of the space group C2/c. Its coordination geometry is intermediate between a trigonal prism (distortion angle φ = 0°) and an antiprism (φ = 60°) with φ = 31.1°. The Fe—N bond lengths lie in the range 1.9376 (13)–1.9617 (13) Å, as expected for tetravalent iron. Structure analysis revealed that three acetic acid molecules additionally co-crystallize per one iron(IV) complex, and one of them is positionally disordered over four positions. In the crystal structure, the ammonium cations, complex dianions and acetic acid molecules are interconnected by an intricate system of hydrogen bonds, mainly via the oxamide oxygen atoms acting as acceptors. Full Article text
xi Synthesis, crystal structure and properties of poly[(μ-2-methylpyridine N-oxide-κ2O:O)bis(μ-thiocyanato-κ2N:S)cobalt(II)] By journals.iucr.org Published On :: 2024-01-01 The title compound, [Co(NCS)2(C6H7NO)]n or Co(NCS)2(2-methylpyridine N-oxide), was prepared by the reaction of Co(NCS)2 and 2-methylpyridine N-oxide in methanol. All crystals obtained by this procedure show reticular pseudo-merohedric twinning, but after recrystallization, one crystal was found that had a minor component with only a very few overlapping reflections. The asymmetric unit consists of one CoII cation, two thiocyanate anions and one 2-methylpyridine N-oxide coligand in general positions. The CoII cations are octahedrally coordinated by two O-bonding 2-methylpyridine N-oxide ligands, as well as two S- and two N-bonding thiocyanate anions, and are connected via μ-1,3(N,S)-bridging thiocyanate anions into chains that are linked by μ-1,1(O,O) bridging coligands into layers. No pronounced directional intermolecular interactions are observed between the layers. The 2-methylpyridine coligand is disordered over two orientations and was refined using a split model with restraints. Powder X-ray diffraction (PXRD) indicates that a pure sample was obtained and IR spectroscopy confirms that bridging thiocyanate anions are present. Thermogravimetry and differential thermoanalysis (TG-DTA) shows one poorly resolved mass loss in the TG curve that is accompanied by an exothermic and an endothermic signal in the DTA curve, which indicate the decomposition of the 2-methylpyridine N-oxide coligands. Full Article text
xi Synthesis, crystal structure and thermal properties of dibromidobis(2-methylpyridine N-oxide-κO)cobalt(II) By journals.iucr.org Published On :: 2024-01-12 Reaction of CoBr2 with 2-methylpyridine N-oxide in n-butanol leads to the formation of the title compound, [CoBr2(C6H7NO)2] or [CoBr2(2-methylpyridine N-oxide)2]. Its asymmetric unit consists of one CoII cation as well as two bromide anions and two 2-methylpyridine N-oxide coligands in general positions. The CoII cations are tetrahedrally coordinated by two bromide anions and two 2-methylpyridine N-oxides, forming discrete complexes. In the crystal structure, these complexes are linked predominantly by weak C–H⋯Br hydrogen bonding into chains that propagate along the crystallographic a-axis. Powder X-ray diffraction (PXRD) measurements indicate that a pure phase was obtained. Thermoanalytical investigations prove that the title compound melts before decomposition; before melting, a further endothermic signal of unknown origin was observed that does not correspond to a phase transition. Full Article text
xi Synthesis and crystal structure of diisothiocyanatotetrakis(4-methylpyridine N-oxide)cobalt(II) and diisothiocyanatotris(4-methylpyridine N-oxide)cobalt(II) showing two different metal coor By journals.iucr.org Published On :: 2024-01-26 The reaction of Co(NCS)2 with 4-methylpyridine N-oxide (C6H7NO) leads to the formation of two compounds, namely, tetrakis(4-methylpyridine N-oxide-κO)bis(thiocyanato-κN)cobalt(II), [Co(NCS)2(C6H7NO)4] (1), and tris(4-methylpyridine N-oxide-κO)bis(thiocyanato-κN)cobalt(II), [Co(NCS)2(C6H7NO)3] (2). The asymmetric unit of 1 consists of one CoII cation located on a centre of inversion, as well as one thiocyanate anion and two 4-methylpyridine N-oxide coligands in general positions. The CoII cations are octahedrally coordinated by two terminal N-bonding thiocyanate anions in trans positions and four 4-methylpyridine N-oxide ligands. In the extended structure, these complexes are linked by C—H⋯O and C—H⋯S interactions. In compound 2, two crystallographically independent complexes are present, which occupy general positions. In each of these complexes, the CoII cations are coordinated in a trigonal–bipyramidal manner by two terminal N-bonding thiocyanate anions in axial positions and by three 4-methylpyridine N-oxide ligands in equatorial positions. In the crystal, these complex molecules are linked by C—H⋯S interactions. For compound 2, a nonmerohedral twin refinement was performed. Powder X-ray diffraction (PXRD) reveals that 2 was nearly obtained as a pure phase, which is not possible for compound 1. Differential thermoanalysis and thermogravimetry data (DTA–TG) show that compound 2 start to decompose at about 518 K. Full Article text
xi Crystal structure of diethylammonium dioxido{Z)-N-[(pyridin-2-yl)carbonylazanidyl]pyridine-2-carboximidato}vanadate(1−) monohydrate By journals.iucr.org Published On :: 2024-02-08 The title compound, (C4H12N)[V(C12H8N4O2)O2]·H2O, was synthesized via aerial oxidation on refluxing picolinohydrazide with ethyl picolinate followed by addition of VIVO(acac)2 and diethylamine in methanol. It crystallizes in the triclinic crystal system in space group Poverline{1}. In the complex anion, the dioxidovanadium(V) moiety exhibits a distorted square-pyramidal geometry. In the crystal, extensive hydrogen bonding links the water molecule to two complex anions and one diethylammonium ion. One of the CH2 groups in the diethylamine is disordered over two sets of sites in a 0.7:0.3 ratio. Full Article text
xi Synthesis, characterization, and crystal structure of 2-(2-azidophenyl)-3-oxo-3H-indole 1-oxide By journals.iucr.org Published On :: 2024-02-20 An attempt to explore the reactivity of the nitro group in the presence of gold catalysis in comparison to the azide group yielded intriguing results. Surprisingly, only the nitro group exhibited reactivity, ultimately giving rise to the formation of the title isatogen, C14H8N4O2. In the crystal structure, weak C—H⋯O hydrogen bonds and π–π stacking interactions link the molecules. The structure exhibits disorder of the molecule. Full Article text
xi Crystal structure of tetrakis(μ-2-hydroxy-3,5-diisopropylbenzoato)bis[(dimethyl sulfoxide)copper(II)] By journals.iucr.org Published On :: 2024-02-27 Metal complexes of 3,5-diisopropylsalicylate are reported to have anti-inflammatory and anti-convulsant activities. The title binuclear copper complex, [Cu2(C13H17O3)4(C2H6OS)2] or [Cu(II)2(3,5-DIPS)4(DMSO)2], contains two five-coordinate copper atoms that are bridged by four 3,5-diisopropylsalicylate ligands and capped by two axial dimethyl sulfoxide (DMSO) moieties. Each copper atom is attached to four oxygen atoms in an almost square-planar fashion, with the addition of a DMSO ligand in an apical position leading to a square-pyramidal arrangement. The hydroxy group of the diisopropylsalicylate ligands participates in intramolecular O—H⋯O hydrogen-bonding interactions. Full Article text
xi The unanticipated oxidation of a tertiary amine in a tetracyclic glyoxal-cyclam condensate yielding zinc(II) coordinated to a sterically hindered amine oxide By journals.iucr.org Published On :: 2024-03-06 The complex, trichlorido(1,4,11-triaza-8-azoniatetracyclo[6.6.2.04,16.011,15]hexadecane 1-oxide-κO)zinc(II) monohydrate, [ZnCl3(C12H23N4O)]·H2O, (I), has monoclinic symmetry (space group P21/n) at 120 K. The zinc(II) center adopts a slightly distorted tetrahedral coordination geometry and is coordinated by three chlorine atoms and the oxygen atom of the oxidized tertiary amine of the tetracycle. The amine nitrogen atom, inside the ligand cleft, is protonated and forms a hydrogen bond to the oxygen of the amine oxide. Additional hydrogen-bonding interactions involve the protonated amine, the water solvate oxygen atom, and one of the chloro ligands. Full Article text
xi Crystal structure and Hirshfeld surface analysis of (1H-imidazole-κN3)[4-methyl-2-({[2-oxido-5-(2-phenyldiazen-1-yl)phenyl]methylidene}amino)pentanoate-κ3O,N,O']copper(II) By journals.iucr.org Published On :: 2024-04-11 The title copper(II) complex, [Cu(C18H19N3O3)(C3H4N2)], consists of a tridentate ligand synthesized from l-leucine and azobenzene-salicylaldehyde. One imidazole molecule is additionally coordinated to the copper(II) ion in the equatorial plane. The crystal structure features N—H⋯O hydrogen bonds. A Hirshfeld surface analysis indicates that the most important contributions to the packing are from H⋯H (52.0%) and C⋯H/H⋯C (17.9%) contacts. Full Article text
xi Synthesis, crystal structure and properties of the trigonal–bipyramidal complex tris(2-methylpyridine N-oxide-κO)bis(thiocyanato-κN)cobalt(II) By journals.iucr.org Published On :: 2024-04-11 Reaction of Co(NCS)2 with 2-methylpyridine N-oxide in a 1:3 ratio in n-butanol leads to the formation of crystals of tris(2-methylpyridine N-oxide-κO)bis(thiocyanato-κN)cobalt(II), [Co(NCS)2(C6H7NO)3]. The asymmetric unit of the title compound consists of one CoII cation two thiocyanate anions and three crystallographically independent 2-methylpyridine N-oxide coligands in general positions. The CoII cations are trigonal–bipyramidally coordinated by two terminal N-bonding thiocyanate anions in the trans-positions and three 2-methylpyridine N-oxide coligands into discrete complexes. These complexes are linked by intermolecular C–H⋯S interactions into double chains that elongate in the c-axis direction. Powder X-ray diffraction (PXRD) measurements prove that all batches are always contaminated with an additional and unknown crystalline phase. Thermogravimetry and differential analysis of crystals selected by hand reveal that the title compound decomposes at about 229°C in an exothermic reaction. At about 113°C a small endothermic signal is observed that, according to differential scanning calorimetry (DSC) measurements, is irreversible. PXRD measurements of the residue prove that a poorly crystalline and unknown phase has formed and thermomicroscopy indicates that some phase transition occurs that is accompanied with a color change of the title compound. Full Article text
xi Synthesis, crystal structure and thermal properties of the dinuclear complex bis(μ-4-methylpyridine N-oxide-κ2O:O)bis[(methanol-κO)(4-methylpyridine N-oxide-κO)bis(thiocyanato-κN)cobalt(II)] By journals.iucr.org Published On :: 2024-04-18 Reaction of Co(NCS)2 with 4-methylpyridine N-oxide in methanol leads to the formation of crystals of the title compound, [Co2(NCS)4(C6H7NO)4(CH4O)2] or Co2(NCS)4(4-methylpyridine N-oxide)4(methanol)2. The asymmetric unit consist of one CoII cation, two thiocyanate anions, two 4-methylpyridine N-oxide coligands and one methanol molecule in general positions. The H atoms of one of the methyl groups are disordered and were refined using a split model. The CoII cations octahedrally coordinate two terminal N-bonded thiocyanate anions, three 4-methylpyridine N-oxide coligands and one methanol molecule. Each two CoII cations are linked by pairs of μ-1,1(O,O)-bridging 4-methylpyridine N-oxide coligands into dinuclear units that are located on centers of inversion. Powder X-ray diffraction (PXRD) investigations prove that the title compound is contaminated with a small amount of Co(NCS)2(4-methylpyridine N-oxide)3. Thermogravimetric investigations reveal that the methanol molecules are removed in the beginning, leading to a compound with the composition Co(NCS)2(4-methylpyridine N-oxide), which has been reported in the literature and which is of poor crystallinity. Full Article text
xi Dimeric ethyltin(IV)–dibromide–hydroxide–N,N-dimethylformamide By journals.iucr.org Published On :: 2024-04-26 Di-μ-hydroxido-bis[dibromido(dimethylformamide-κO)ethyltin(IV)], [Sn2Br4(C2H5)2(OH)2(C3H7NO)2], was prepared from ethyltin(IV) bromide and N,N-dimethylformamide (DMF) in air. The crystal structure exhibits the typical structural features of dimeric Lewis-base-stabilized monoorganotin(IV)–dihalide–hydroxides, RSnHal2(OH), i.e. two octahedrally coordinated Sn atoms are linked together via two bridging hydroxide groups, resulting in a centrosymmetric four-membered rhomboid-like Sn–OH ring with acute angles at the Sn atom, obtuse angles at the O atoms and two different tin–oxygen bond lengths. With the shorter bond trans to the ethyl group, this observation underlines once more the so-called trans-strengthening effect in monoorganotin(IV) compounds with octahedrally coordinated Sn atoms. Differences and similarities in the bond lengths and angles in the four-membered Sn–OH rings have been worked out for the rings in dimeric diorganotin(IV)–halide–hydroxides, [R2SnHal(OH)]2, and hydrates of dimeric tin(IV)–trihalide–hydroxide–aqua–hydrates, [SnHal3(OH)(H2O)]2·nH2O. Full Article text
xi Syntheses and crystal structures of the five- and sixfold coordinated complexes diisoselenocyanatotris(2-methylpyridine N-oxide)cobalt(II) and diisoselenocyanatotetrakis(2-methylpyridine N- By journals.iucr.org Published On :: 2024-06-07 The reaction of CoBr2, KNCSe and 2-methylpyridine N-oxide (C6H7NO) in ethanol leads to the formation of crystals of [Co(NCSe)2(C6H7NO)3] (1) and [Co(NCSe)2(C6H7NO)4] (2) from the same reaction mixture. The asymmetric unit of 1 is built up of one CoII cation, two NCSe− isoselenocyanate anions and three 2-methylpyridine N-oxide coligands, with all atoms located on general positions. The asymmetric unit of 2 consists of two cobalt cations, four isoselenocanate anions and eight 2-methylpyridine N-oxide coligands in general positions, because two crystallographically independent complexes are present. In compound 1, the CoII cations are fivefold coordinated to two terminally N-bonded anionic ligands and three 2-methylpyridine N-oxide coligands within a slightly distorted trigonal–bipyramidal coordination, forming discrete complexes with the O atoms occupying the equatorial sites. In compound 2, each of the two complexes is coordinated to two terminally N-bonded isoselenocyanate anions and four 2-methylpyridine N-oxide coligands within a slightly distorted cis-CoN2O4 octahedral coordination geometry. In the crystal structures of 1 and 2, the complexes are linked by weak C—H⋯Se and C—H⋯O contacts. Powder X-ray diffraction reveals that neither of the two compounds were obtained as a pure crystalline phase. Full Article text
xi Crystal structure of catena-poly[[methanoldioxidouranium(VI)]-μ-2-[5-(2-oxidophenyl)-1H-1,2,4-triazol-3-yl]acetato-κ2O:O'] By journals.iucr.org Published On :: 2024-07-12 In the title complex, [U(C10H7N3O3)O2(CH3OH)]n, the UVI cation has a typical pentagonal–bipyramidal environment with the equatorial plane defined by one N and two O atoms of one doubly deprotonated 2-[5-(2-hydroxyphenyl)-1H-1,2,4-triazol-3-yl]acetic acid ligand, a carboxylate O atom of the symmetry-related ligand and the O atom of the methanol molecule [U—N/Oeq 2.256 (4)–2.504 (5) Å]. The axial positions are occupied by two oxide O atoms. The equatorial atoms are almost coplanar, with the largest deviation from the mean plane being 0.121 Å for one of the O atoms. The benzene and triazole rings of the tetradentate chelating–bridging ligand are twisted by approximately 21.6 (2)° with respect to each other. The carboxylate group of the ligand bridges two uranyl cations, forming a neutral zigzag chain reinforced by a strong O—H⋯O hydrogen bond. In the crystal, adjacent chains are linked into two-dimensional sheets parallel to the ac plane by C/N—H⋯N/O hydrogen bonding and π–π interactions. Further weak C—H⋯O contacts consolidate the three-dimensional supramolecular architecture. In the solid state, the compound shows a broad medium intensity LMCT transition centred around 463 nm, which is responsible for its red colour. Full Article text
xi Crystal structure of a tris(2-aminoethyl)methane capped carbamoylmethylphosphine oxide compound By journals.iucr.org Published On :: 2024-08-30 The molecular structure of the tripodal carbamoylmethylphosphine oxide compound diethyl {[(5-[2-(diethoxyphosphoryl)acetamido]-3-{2-[2-(diethoxyphosphoryl)acetamido]ethyl}pentyl)carbamoyl]methyl}phosphonate, C25H52N3O12P3, features six intramolecular hydrogen-bonding interactions. The phosphonate groups have key bond lengths ranging from 1.4696 (12) to 1.4729 (12) Å (P=O), 1.5681 (11) to 1.5811 (12) Å (P—O) and 1.7881 (16) to 1.7936 (16) Å (P—C). Each amide group adopts a nearly perfect trans geometry, and the geometry around each phophorus atom resembles a slightly distorted tetrahedron. Full Article text
xi Synthesis and crystal structure of poly[ethanol(μ-4-methylpyridine N-oxide)di-μ-thiocyanato-cobalt(II)] By journals.iucr.org Published On :: 2024-09-20 Reaction of 4-methylpyridine N-oxide and Co(NCS)2 in ethanol as solvent accidentally leads to the formation of single crystals of Co(NCS)2(4-methylpyridine N-oxide)(ethanol) or [Co(NCS)2(C6H7NO)(C2H6O)]n. The asymmetric unit of the title compound consists of one CoII cation, two crystallographically independent thiocyanate anions, one 4-methylpyridine N-oxide coligand and one ethanol molecule on general positions. The cobalt cations are sixfold coordinated by one terminal and two bridging thiocyanate anions, two bridging 4-methylpyridine N-oxide coligands and one ethanol molecule, with a slightly distorted octahedral geometry. The cobalt cations are linked by single μ-1,3(N,S)-bridging thiocyanate anions into corrugated chains, that are further connected into layers by pairs of μ-1,1(O,O)-bridging 4-methylpyridine N-oxide coligands. The layers are parallel to the bc plane and are separated by the methyl groups of the 4-methylpyridine N-oxide coligands. Within the layers, intralayer hydrogen bonding is observed. Full Article text
xi The cadmium oxidotellurates(IV) Cd5(TeO3)4(NO3)2 and Cd4Te5O14 By journals.iucr.org Published On :: 2024-11-05 Monoclinic single crystals of Cd5(TeO3)4(NO3)2 (space group P21/c), pentacadmium tetrakis[oxidotellurate(IV)] dinitrate, and of Cd4Te5O14 (space group C2/c), tetracadmium pentaoxidotellurate(IV), were obtained under the same hydrothermal conditions. Whereas the crystal structure of Cd5(TeO3)4(NO3)2 is distinctively layered, that of Cd4Te5O14 exhibits a tri-periodic framework. In Cd5(TeO3)4(NO3)2, the three CdII atoms have coordination numbers (CN) of 7, 6 and 6. The two types of [CdO6] and the [CdO7] polyhedra [bond lengths range from 2.179 (3) to 2.658 (2) Å] share corners and edges, resulting in layers extending parallel to (100). Both TeIV atoms are coordinated by three oxygen atoms in a trigonal–pyramidal shape. The oxygen atoms of the isolated [TeO3] groups [bond lengths range from 1.847 (3) to 1.886 (3) Å] all are part of the cadmium–oxygen layer. The electron lone pairs ψ of the TeIV atoms are directed away from the layer on both sides. The available interlayer space is co-occupied by the nitrate group, which is directly connected with two of its O atoms to the layer whereas the third O atom is solely bonded to the N atom and points towards the adjacent layer. In Cd4Te5O14, all three unique CdII atoms are coordinated by six oxygen atoms, considering Cd—O distances from 2.235 (2) to 2.539 (2) Å. By edge- and corner-sharing, the distorted [CdO6] polyhedra form an open framework that is partially filled with three different stereochemically active TeIV atoms. All of them exhibit a CN of 4, with Te—O bonds in a range from 1.859 (2) to 2.476 (2) Å. The corresponding [TeO4] units are linked to each other by corner- and edge-sharing, forming infinite helical 1∞[Te10O28] chains extending parallel to [203]. The connectivity in the chains can be described as (⋯–⋄–⋄=⋄–⋄–⋄–⋄–⋄=⋄–⋄–⋄–⋯)n where ‘⋄’ denotes a [TeO4] unit, ‘–’ a linkage via corners and ‘=’ a linkage via edges. Such a structural motif is unprecedented in the crystal chemistry of oxidotellurate(IV) compounds. Full Article text
xi Crystal structure and Hirshfeld surface analysis of bis(benzoylacetonato)(ethanol)dioxidouranium(VI) By journals.iucr.org Published On :: 2024-11-05 A new uranium metal–organic complex salt, [U(C10H9O2)2O2(C2H6O)], with benzoyl acetone, namely, bis(benzoylacetonato)(ethanol)dioxidouranium(VI), was synthesized. The compound has monoclinic P21/n symmetry. The geometry of the seven-coordinate U atom is pentagonal bipyramidal, with the uranyl oxygen atoms in apical positions. In the complex, the ligands bind to the metal through oxygen atoms. Additional weak O—H⋯O contacts between the cations and anions consolidate the three-dimensional arrangement of the structure. On the Hirshfeld surface, the largest contributions come from the short contacts such as van der Waals forces, including H⋯H, O⋯H and C⋯H. Interactions including C⋯C and O⋯C contacts were also observed; however, their contribution to the overall cohesion of the crystal structure is minor. A packing analysis was performed to check the strength of the crystal packing. Full Article text
xi X-ray diffraction from dislocation half-loops in epitaxial films By journals.iucr.org Published On :: 2024-02-23 X-ray diffraction from dislocation half-loops consisting of a misfit segment with two threading arms extending from it to the surface is calculated by the Monte Carlo method. The diffraction profiles and reciprocal space maps are controlled by the ratio of the total lengths of the misfit and the threading segments of the half-loops. A continuous transformation from the diffraction characteristic of misfit dislocations to that of threading dislocations with increasing thickness of epitaxial film is studied. Diffraction from dislocations with edge- and screw-type threading arms is considered and the contributions of the two types of dislocations are compared. Full Article text
xi Observations of specimen morphology effects on near-zone-axis convergent-beam electron diffraction patterns By journals.iucr.org Published On :: 2024-03-21 This work presents observations of symmetry breakages in the intensity distributions of near-zone-axis convergent-beam electron diffraction (CBED) patterns that can only be explained by the symmetry of the specimen and not the symmetry of the unit cell describing the atomic structure of the material. The specimen is an aluminium–copper–tin alloy containing voids many tens of nanometres in size within continuous single crystals of the aluminium host matrix. Several CBED patterns where the incident beam enters and exits parallel void facets without the incident beam being perpendicular to these facets are examined. The symmetries in their intensity distributions are explained by the specimen morphology alone using a geometric argument based on the multislice theory. This work shows that it is possible to deduce nanoscale morphological information about the specimen in the direction of the electron beam – the elusive third dimension in transmission electron microscopy – from the inspection of CBED patterns. Full Article text
xi TORO Indexer: a PyTorch-based indexing algorithm for kilohertz serial crystallography By journals.iucr.org Published On :: 2024-06-18 Serial crystallography (SX) involves combining observations from a very large number of diffraction patterns coming from crystals in random orientations. To compile a complete data set, these patterns must be indexed (i.e. their orientation determined), integrated and merged. Introduced here is TORO (Torch-powered robust optimization) Indexer, a robust and adaptable indexing algorithm developed using the PyTorch framework. TORO is capable of operating on graphics processing units (GPUs), central processing units (CPUs) and other hardware accelerators supported by PyTorch, ensuring compatibility with a wide variety of computational setups. In tests, TORO outpaces existing solutions, indexing thousands of frames per second when running on GPUs, which positions it as an attractive candidate to produce real-time indexing and user feedback. The algorithm streamlines some of the ideas introduced by previous indexers like DIALS real-space grid search [Gildea, Waterman, Parkhurst, Axford, Sutton, Stuart, Sauter, Evans & Winter (2014). Acta Cryst. D70, 2652–2666] and XGandalf [Gevorkov, Yefanov, Barty, White, Mariani, Brehm, Tolstikova, Grigat & Chapman (2019). Acta Cryst. A75, 694–704] and refines them using faster and principled robust optimization techniques which result in a concise code base consisting of less than 500 lines. On the basis of evaluations across four proteins, TORO consistently matches, and in certain instances outperforms, established algorithms such as XGandalf and MOSFLM [Powell (1999). Acta Cryst. D55, 1690–1695], occasionally amplifying the quality of the consolidated data while achieving superior indexing speed. The inherent modularity of TORO and the versatility of PyTorch code bases facilitate its deployment into a wide array of architectures, software platforms and bespoke applications, highlighting its prospective significance in SX. Full Article text
xi A simple protocol for determining the zone axis direction from selected-area electron diffraction spot patterns of cubic materials By journals.iucr.org Published On :: 2024-06-18 Using the well known Rn ratio method, a protocol has been elaborated for determining the lattice direction for the 15 most common cubic zone axis spot patterns. The method makes use of the lengths of the three shortest reciprocal-lattice vectors in each pattern and the angles between them. No prior pattern calibration is required for the method to work, as the Rn ratio method is based entirely on geometric relationships. In the first step the pattern is assigned to one of three possible pattern types according to the angles that are measured between the three reciprocal-lattice vectors. The lattice direction [uvw] and possible Bravais type(s) and Laue indices of the corresponding reflections can then be determined by using lookup tables. In addition to determining the lattice direction, this simple geometric analysis allows one to distinguish between the P, I and F Bravais lattices for spot patterns aligned along [013], [112], [114] and [233]. Moreover, the F lattice can always be uniquely identified from the [011] and [123] patterns. Full Article text
xi Coprecipitation of Ce(III) oxide with UO2 By journals.iucr.org Published On :: 2024-09-30 The neutralization of acidic solutions containing U (IV) and Ce (III) at room temperature in glove box atmosphere and in the presence of dithionite results in coprecipitation of these elements as amorphous solid solutions CexU1–xO2±y. The solubilities of the precipitates with different mole fractions (x) of Ce(OH)3 (x = 0.01 or 0.1) were determined in 1 M NaClO4 solutions between pH 2.2 and 12.8 under reducing conditions. The solids were investigated by a variety of methods (chemical analysis, SEM-EDX, XRD, XPS, XAS) to determine the nature of the solid solutions formed, their composition and the valence state of Ce and U. X-ray photoelectron spectroscopy confirmed the oxidation states of the solids both before and after the equilibration as Ce (III) and U (IV). The amorphous coprecipitates reached equilibrium relatively fast (∼1 week). The release of Ce from the coprecipitates was totally dominated by the release of uranium over the whole pH range. The Ce concentrations decrease slightly with the decrease of Ce content in the solid, suggesting that CexU1–xO2±y solids behave thermodynamically as solid solutions. The concentrations of U in equilibrium with the coprecipitate were in excellent agreement with the solubility of UO2(s) under reducing conditions reported in the literature. The conditional solubility product of Ce(OH)3 from the coprecipitate was several orders of magnitude (∼4 in the near neutral pH range and ∼18 in the acidic range) lower than that of pure Ce(OH)3(s). The activities and activity coefficients of Ce(OH)3(s) in the coprecipitate were also estimated. Activity coefficients are much less than 1, indicating that the mixing of Ce(OH)3 with UO2 is highly favorable. Full Article text
xi Shein partners with Stori to launch a credit card in Mexico By thepaypers.com Published On :: Thu, 24 Oct 2024 15:45:00 +0100 Chinese fast-fashion retailer Shein has introduced its first... Full Article
xi 'Red Band Society' ads pulled from LA buses amid complaints of racism, sexism By www.scpr.org Published On :: Fri, 19 Sep 2014 08:56:27 -0700 "Red Band Society," premieres on Fox September 17th, starring Octavia Spencer, Charlie Rowe and Nolan Sotillo.; Credit: Fox Television Studios The Los Angeles County Metropolitan Transportation Authority is pulling ads for the Fox television show "Red Band Society" from nearly 200 buses amid complaints they are racist and offensive to women. The ads show the ensemble cast's members in front of a wall with graffiti describing their characters. A denigrating word for a woman is used to describe the show's star, Octavia Spencer's character. The Los Angeles Times reports transit officials began pulling the ads on Wednesday. They had been up for five weeks. The Red Band Society also shared the ad on its Facebook page in August. Facebook: #RedBandSociety ad But it's since edited it to look like this. Photo: New ad via Facebook Protesters who attended Thursday's transit agency board meeting complained the depiction of Spencer's character is racist and offensive to women. The actress, who plays a nurse in the hospital drama, is black. She won a supporting actress Oscar for her role in "The Help." Full Article
xi Mastercard expands installments, unlocking flexible payment options By thepaypers.com Published On :: Mon, 28 Oct 2024 09:37:00 +0100 Mastercard has expanded its US... Full Article
xi Pix by Proximity is introduced By thepaypers.com Published On :: Tue, 05 Nov 2024 15:46:00 +0100 Pix by Proximity has been introduced by the Central bank of Brazil,... Full Article
xi Network International, Tamara to bring flexible payments to MEA By thepaypers.com Published On :: Fri, 08 Nov 2024 11:28:00 +0100 Full Article
xi Marine Mineral Formations in the Arctic Ocean Challenge Existing Geologic Theories By www.usgs.gov Published On :: Tue, 12 Nov 2024 14:02:54 EST A new study from USGS describes a previously unknown process of marine mineral formation in the Arctic Ocean, driven by frictional heating along tectonic faults rather than by hydrothermal activity. Full Article
xi Study finds big increase in ocean carbon dioxide absorption along West Antarctic Peninsula By news.science360.gov Published On :: 2019-08-29T07:00:00Z Full Text:A new study shows that the West Antarctic Peninsula is experiencing some of the most rapid climate change on Earth, featuring dramatic increases in temperatures, retreats in glaciers and declines in sea ice. The Southern Ocean absorbs nearly half of the carbon dioxide -- the key greenhouse gas linked to climate change -- that is absorbed by all the world's oceans. The study tapped an unprecedented 25 years of oceanographic measurements in the Southern Ocean and highlights the need for more monitoring in the region. The research revealed that carbon dioxide absorption by surface waters off the West Antarctic Peninsula is linked to the stability of the upper ocean, along with the amount and type of algae present. A stable upper ocean provides algae with ideal growing conditions. During photosynthesis, algae remove carbon dioxide from the surface ocean, which in turn draws carbon dioxide out of the atmosphere. From 1993 to 2017, changes in sea ice dynamics off the West Antarctic Peninsula stabilized the upper ocean, resulting in greater algal concentrations and a shift in the mix of algal species. That's led to a nearly five-fold increase in carbon dioxide absorption during the summertime. The research also found a strong north-south difference in the trend of carbon dioxide absorption. The southern portion of the peninsula, which to date has been less impacted by climate change, experienced the most dramatic increase in carbon dioxide absorption, demonstrating the poleward progression of climate change in the region.Image credit: Drew Spacht/The Ohio State University Full Article
xi Maximize Your IT Infrastructure; Maximize Business Productivity By www.itsecurity.com Published On :: Fri, 26 Mar 2010 23:29:07 +0000 On-Demand Webinar >Watch Now!>>SPONSORED BY: Qwest Business Solutions®Watch this FREE on-demand 30-minute webcast to hear Qwest Communications CIO, Girish Varma, Qwest’s Director of... Full Article
xi John Kerry Says Climate Change Is An 'Existential' Crisis By www.scpr.org Published On :: Fri, 23 Apr 2021 17:20:13 -0700 Special Presidential Envoy for Climate John Kerry tells NPR that the U.S., China and other major emitters aren't doing enough to stem climate change.; Credit: Alex Wong/Getty Images Ari Shapiro | NPRPresident Biden is pledging to reduce greenhouse gas emissions by 50-52% from 2005 levels by 2030. It's an ambitious goal that requires transforming much of the economy. Renewable energy would need to make up half of the U.S. power supply from roughly 21% currently. Electric cars make up about 2% of sales now — by 2030, at least half, potentially all, new car sales would need to be electric, according to estimates. Many industrial manufacturing facilities would need to use technologies that haven't been developed. It's part of Biden's effort to get the U.S. on track to reach the goals of the 2015 Paris Climate Agreement to keep global temperatures from rising more than 1.5 degrees Celsius. Former President Donald Trump withdrew the U.S. from the agreement but Biden has formally rejoined. John Kerry is Biden's special envoy for climate, a position that involves meeting with countries around the world about efforts to stem emissions. He calls the threat of climate change "existential." "That means life and death. And the question is, are we behaving as if it is? And the answer is no," Kerry said in an interview on NPR's All Things Considered. This interview has been edited for length and clarity and includes extended Web-only answers. Interview Highlights Is this more a matter of shoot for the moon and if you miss, at least you'll land among the stars? No, I think it's achievable. And I think that people who've really studied this, analyzed it and thought about it for a long period of time believe it is achievable. Already the [car] marketplace is moving towards electric. I mean, you know, Joe Biden didn't create the value of Tesla as the most valuable automobile company in the world. The market did that. And the market did it because that's where people are moving. The scale of change that you're talking about in the timeframe that is required is something we've never seen in human history. Let me put it to you this way. How many politicians, how many scientists, how many people have stood up and said, "This is existential for us on this planet"? Existential. That means life and death. And the question is, are we behaving as if it is? And the answer is no. So why are younger generation folks so angry? Why are they standing up and demonstrating and asking adults to accept adult responsibility to move our nations in the right direction? Because the scientists are telling them that. They learn about this in high school and college. They read. They know what's happening. They know we're experiencing the hottest day in human history, the hottest week, the hottest month, the hottest year. And we see the results. Fires, floods, mudslides, drought, crop disruption, ice melting in the Arctic, run the list. Climate change is still seen as a partisan issue in the U.S., and Republicans could take over Congress next year. A Republican could win the White House in three years. So why should global leaders view this as a reliable commitment from the United States when GOP leaders have not bought in? For two reasons. No. 1, when Donald Trump was president of the United States and he pulled out of the agreement, 37 governors in the United States, Republican and Democrats alike, stood up and said, "We're still in." And states, those 37 states, have passed renewable portfolio laws. So at the state level, people are moving because they know it's better for their state. It's a safer, better delivery of power to their state, and it's the way it's going to move. The second part of the answer: Masses of capital, trillions of dollars, are going to move into the energy market, which is the largest market the world has ever seen and going to grow now. Multiple double-digit trillions of dollars of market. And no politician can come along and tell those banks, or those asset managers or those investors or those venture capitalists or the companies, the corporations that are doing this, they know this is where the market's going to be in the future. If the $2 trillion infrastructure and jobs plan that the president has put forth does not pass the Senate, does this goal to cut emissions in half by 2030 effectively die with the bill? Well, it doesn't die, but it certainly takes a blow, a serious one. But the companies I've talked about are going to move in this direction no matter what. I mean, if you look at the biggest companies in America, these folks are all pushing to get this done because they know that the world is going to be better off and that their businesses are going to be better off if we do that. This is a real challenge for all of us, and I think people are waking up to it all around the world. Let me ask you a question. Why do you think 40 heads of state, including President Xi of China, President Putin of Russia, Prime Minister Modi of India, huge populations come together and say, "We have to do this"? Do they know something that some of these opponents of it don't know or aren't willing to admit? I mean, the only leader in the entire world that saw fit to pull out of the Paris agreement was Donald Trump. But it's so easy to make commitments and we haven't seen countries follow through on those commitments. This is accurate. They're doing things; they're not doing enough. There are very few countries that are doing enough. Most countries are not. And of the 20 countries that equal 81% of all the emissions, they are the critical ones that have to do more. And we're among them. We are 15% of all the world's emissions. China is 30%. Does China need to do more? Absolutely. All of the 20 need to do more. Copyright 2021 NPR. To see more, visit https://www.npr.org. This content is from Southern California Public Radio. View the original story at SCPR.org. Full Article
xi Lee Industries of Conover to expand, using existing building, adding 75 jobs By www.catawbacountync.gov Published On :: Wed, 29 Jun 2011 13:05:00 EST Furniture manufacturer Lee Industries, Inc. plans to expand their manufacturing capabilities in Catawba County by extensively redeveloping and renovating the former Conover Chair facility in Conover, N.C. and adding 75 new employees beginning in late 2011. The company will be hiring cutters, sewers, spring-up associates, inside and outside upholsterers, shipping personnel, support staff and more. The average employee wage is expected to be $41,045, nearly $7,000 more than the average pay for workers living in Catawba County. Full Article News Release FYI Please Choose
xi Antioxidants Role in Chronic Disease Prevention Still Uncertain - Huge Doses Considered Risky By Published On :: Mon, 10 Apr 2000 05:00:00 GMT Insufficient evidence exists to support claims that taking megadoses of dietary antioxidants, such as selenium and vitamins C and E, or carotenoids, including beta-carotene, can prevent chronic diseases, says the latest report on Dietary Reference Intakes (DRIs) from the Institute of Medicine of the National Academies. Full Article
xi Need Still Exists for Chemical Pesticides While Alternatives Are Sought By Published On :: Tue, 18 Jul 2000 05:00:00 GMT No justification currently exists for completely abandoning chemical pesticides, says a new report from the National Academies National Research Council. Full Article
xi Statement Regarding New NAS Program on Human Health and Environmental Protection in the Gulf of Mexico By Published On :: Thu, 15 Nov 2012 05:00:00 GMT As part of the $4 billion settlement announced today between the federal government and BP concerning the 2010 Deepwater Horizon disaster, the National Academy of Sciences has been asked to establish a new $350 million, 30-year program on human health and environmental protection in the Gulf of Mexico. Full Article
xi U.S. Tax Code Has Minimal Effect on Carbon Dioxide and Other Greenhouse Gas Emissions, Report Says By Published On :: Thu, 20 Jun 2013 05:00:00 GMT Current federal tax provisions have minimal net effect on greenhouse gas emissions, according to a new report from the National Research Council. Full Article
xi Effective Monitoring to Evaluate Ecological Restoration in the Gulf of Mexico – New Report By Published On :: Tue, 26 Jul 2016 05:00:00 GMT To improve and ensure the efficacy of restoration efforts in the Gulf of Mexico following Deepwater Horizon – the largest oil spill in U.S. history – a new report from the National Academies of Sciences, Engineering, and Medicine recommends a set of best practices for monitoring and evaluating ecological restoration activities. Full Article
xi Statement Regarding National Academies Study on Potential Health Risks of Living in Proximity to Surface Coal Mining Sites in Central Appalachia By Published On :: Mon, 21 Aug 2017 05:00:00 GMT In an August 18 letter, the U.S. Department of the Interior’s Office of Surface Mining Reclamation and Enforcement informed the National Academies of Sciences, Engineering, and Medicine that it should cease all work on a study of the potential health risks for people living near surface coal mine sites in Central Appalachia. Full Article
xi Substantial Gap Exists Between Demand for Organ Transplants in U.S. and Number of Transplants Performed - New Report Offers Ethical, Regulatory, and Policy Framework for Research to Increase Quantity & Quality of Organs For Transplantation, Save Lives By Published On :: Tue, 10 Oct 2017 05:00:00 GMT The number of patients in the U.S. awaiting organ transplantation outpaces the amount of transplants performed in the U.S., and many donated organs are not transplanted each year due to several factors, such as poor organ function, says a new report from the National Academies of Sciences, Engineering, and Medicine. Full Article
xi New Report Calls for Comprehensive Research Campaign to Better Understand, Predict Gulf of Mexico’s Loop Current System By Published On :: Wed, 03 Jan 2018 06:00:00 GMT A new report from the National Academies of Sciences, Engineering, and Medicine calls for an international, multi-institutional comprehensive campaign of research, observation, and analysis activities that would help improve understanding and prediction of the Gulf of Mexico’s Loop Current System (LCS). Full Article
xi National Academies’ Gulf Research Program Announces $10 Million Grant Opportunity for Enhancing Coastal Community Resilience in the Gulf of Mexico Region By Published On :: Wed, 25 Jul 2018 05:00:00 GMT The Gulf Research Program (GRP) of the National Academies of Sciences, Engineering, and Medicine today announced a new grant opportunity focused on enhancing coastal community resilience and well-being in the Gulf of Mexico region. Full Article
xi Technologies That Remove Carbon Dioxide From Air and Sequester It Need to Play a Large Role in Mitigating Climate Change, Says New Report By Published On :: Wed, 24 Oct 2018 05:00:00 GMT To achieve goals for climate and economic growth, “negative emissions technologies” (NETs) that remove and sequester carbon dioxide from the air will need to play a significant role in mitigating climate change, says a new report from the National Academies of Sciences, Engineering, and Medicine. Full Article
xi National Academies Gulf Research Program to Collaborate with Shell on Gulf of Mexico Ocean Observation Effort By Published On :: Wed, 14 Nov 2018 06:00:00 GMT The Gulf Research Program of the National Academies of Sciences, Engineering, and Medicine today announced a new collaboration with Shell and others to provide $1 million in funding support for a pilot effort to convert an existing ocean mooring owned by Shell into the first long-term deep ocean observatory in the Gulf of Mexico. Full Article
xi Research Campaign to Advance Understanding of Gulf of Mexico Loop Current Moves Forward By Awarding $10.3 Million in Initial Grants By Published On :: Wed, 19 Dec 2018 06:00:00 GMT Following recommendations from a National Academies of Sciences, Engineering, and Medicine report released earlier this year, the National Academies’ Gulf Research Program (GRP) is developing a long-term research campaign to improve understanding and prediction of the Gulf of Mexico Loop Current System (LCS). Full Article
xi $2.5 Million in Grants Available to Advance Understanding and Prediction of Gulf of Mexico Loop Current By Published On :: Wed, 06 Mar 2019 06:00:00 GMT The Gulf Research Program (GRP) of the National Academies of Sciences, Engineering, and Medicine today announced a new funding opportunity to provide up to $2.5 million in grants to foster innovative approaches that support its ongoing efforts to improve understanding and prediction of the Gulf of Mexico Loop Current System (LCS). Full Article