It is shown how to reconstruct the stacking sequence from the pairwise correlation functions between layers in close-packed structures. First, of theoretical interest, the analytical formulation and solution of the problem are presented when the exact pairwise correlation counts are known. In the second part, the practical problem is approached. A simulated annealing procedure is developed to solve the problem using as initial guess approximate solutions from previous treatments. The robustness of the procedure is tested with synthetic data, followed by an experimental example. The developed approach performs robustly over different synthetic and experimental data, comparing favorably with the reported methods.

The methods for X-ray crystal orientation are rapidly evolving towards versatility, fewer goniometry measurements, automation, high accuracy and precision. One method that attracts a lot of attention is energy-dispersive X-ray diffraction (EDXRD) which is based on detecting reflections from crystallographic planes in a crystal at fixed angles of a parallel polychromatic X-ray incident beam. In theory, an EDXRD peak can move in a diffraction pattern as a function of a crystallographic plane d-spacing and its orientation relative to a fixed direction in space can change also. This is equivalent to the possibility of measuring the orientation of single crystals. The article provides a modeling for the EDXRD method whose main feature is the nonmoving crystal in the sense of traditional goniometry where the angle measurements of diffracting planes are a must. The article defines the equation of orientation for the method and shows the derivation in great detail. It is shown that the exact solutions of the equations can be obtained using the generalized reduced gradient method, a mathematical subroutine that is implemented in Excel software. The significance and scientific impact of the work are discussed along with the validated tested results.

To date X-ray protein crystallography is the most successful technique available for the determination of high-resolution 3D structures of biological molecules and their complexes. In X-ray protein crystallography the structure of a protein is refined against the set of observed Bragg reflections from a protein crystal. The resolution of the refined protein structure is limited by the highest angle at which Bragg reflections can be observed. In addition, the Bragg reflections alone are typically insufficient (by a factor of two) to determine the structure ab initio, and so prior information is required. Crystals formed from an imperfect packing of the protein molecules may also exhibit continuous diffraction between and beyond these Bragg reflections. When this is due to random displacements of the molecules from each crystal lattice site, the continuous diffraction provides the necessary information to determine the protein structure without prior knowledge, to a resolution that is not limited by the angular extent of the observed Bragg reflections but instead by that of the diffraction as a whole. This article presents an iterative projection algorithm that simultaneously uses the continuous diffraction as well as the Bragg reflections for the determination of protein structures. The viability of this method is demonstrated on simulated crystal diffraction.

Diffuse scattering is a rich source of information about disorder in crystalline materials, which can be modelled using atomistic techniques such as Monte Carlo and molecular dynamics simulations. Modern X-ray and neutron scattering instruments can rapidly measure large volumes of diffuse-scattering data. Unfortunately, current algorithms for atomistic diffuse-scattering calculations are too slow to model large data sets completely, because the fast Fourier transform (FFT) algorithm has long been considered unsuitable for such calculations [Butler & Welberry (1992). J. Appl. Cryst. 25, 391–399]. Here, a new approach is presented for ultrafast calculation of atomistic diffuse-scattering patterns. It is shown that the FFT can actually be used to perform such calculations rapidly, and that a fast method based on sampling theory can be used to reduce high-frequency noise in the calculations. These algorithms are benchmarked using realistic examples of compositional, magnetic and displacive disorder. They accelerate the calculations by a factor of at least 102, making refinement of atomistic models to large diffuse-scattering volumes practical.

In certain scenarios, a Subsystem Reference block changes its position. It can happen during: 

1. Loading of top model which contains the Subsystem Reference block 
2. Synchronization of Subsystem Reference block's contents
3. Converting a subsystem to Subsystem Reference block 

Who’s Who in Payments – Complete Overview of Key Payment Providers encompasses key trends in the payments industry.

Individual white paper containing all the latest updates to the Open Banking Global State of Play. Research conducted by The Paypers and Innopay

In the title compound, C16H14Cl2FN3, the dihedral angle between the two aromatic rings is 64.12 (14)°. The crystal structure is stabilized by a short Cl...H contact, C—Cl...π and van der Waals interactions. The Hirshfeld surface analysis and two-dimensional fingerprint plots show that H...H (33.3%), Cl...H/H...Cl (22.9%) and C...H/H...C (15.5%) interactions are the most important contributors towards the crystal packing.

The title compound, C14H16, exhibits exceptionally weak intermolecular C—H...π hydrogen bonding of the ethynyl groups, with the corresponding H...π separations [2.91 (2) and 3.12 (2) Å] exceeding normal vdW distances. This bonding complements distal contacts of the CH (aliphatic)...π type [H...π = 3.12 (2)–3.14 (2) Å] to sustain supramolecular layers. Hirshfeld surface analysis of the title compound suggests a relatively limited significance of the C...H/H...C contacts to the crystal packing (24.6%) and a major contribution from H...H contacts accounting 74.9% to the entire surface.

The cationic complex in the title compound, [Ir(C9H7N2)2(C12H8N2)]PF6, comprises two phenylpyrazole (ppz) cyclometallating ligands and one 1,10-phenanthroline (phen) ancillary ligand. The asymmetric unit consists of one [Ir(ppz)2(phen)]+ cation and one [PF6]− counter-ion. The central IrIII ion is six-coordinated by two N atoms and two C atoms from the two ppz ligands as well as by two N atoms from the phen ligand within a distorted octahedral C2N4 coordination set. In the crystal structure, the [Ir(ppz)2(phen)]+ cations and PF6− counter-ions are connected with each other through weak intermolecular C—H...F hydrogen bonds. Additional C—H...π interactions between the rings of neighbouring cations consolidate the three-dimensional network. Electron density associated with additional disordered solvent molecules inside cavities of the structure was removed with the SQUEEZE procedure in PLATON [Spek (2015). Acta Cryst. C71, 9–18]. The given chemical formula and other crystal data do not take into account the unknown solvent molecule(s). The title compound has a different space-group symmetry (C2/c) from its solvatomorph (P21/c) comprising 1.5CH2Cl2 solvent molecules per ion pair.

The asymmetric unit of the title compound, C17H14N2O, contains two independent molecules each consisting of perimidine and phenol units. The tricyclic perimidine units contain naphthalene ring systems and non-planar C4N2 rings adopting envelope conformations with the C atoms of the NCN groups hinged by 44.11 (7) and 48.50 (6)° with respect to the best planes of the other five atoms. Intramolecular O—H...N hydrogen bonds may help to consolidate the molecular conformations. The two independent molecules are linked through an N—H...O hydrogen bond. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H...H (52.9%) and H...C/C...H (39.5%) interactions. Hydrogen bonding and van der Waals interactions are the dominant interactions in the crystal packing. Density functional theory (DFT) optimized structures at the B3LYP/ 6–311 G(d,p) level are compared with the experimentally determined molecular structure in the solid state. The HOMO–LUMO behaviour was elucidated to determine the energy gap.

In the title compound, C17H27NO2, the piperidine ring has a chair conformation and is positioned normal to the benzene ring. In the crystal, molecules are linked by C—H...O hydrogen bonds, forming chains propagating along the c-axis direction.

The new copper(II) complex, namely, di-μ-chlorido-bis{chlorido[methyl(pyridin-2-ylmethylidene)amine-κ2N,N']copper(II)}, [Cu2Cl4(C7H8N2)2], (I), with the ligand 2-pyridylmethyl-N-methylimine (L, a product of Schiff base condensation between methylamine and 2-pyridinecarbaldehyde) is built of discrete centrosymmetric dimers. The coordination about the CuII ion can be described as distorted square pyramidal. The base of the pyramid consists of two nitrogen atoms from the bidentate chelate L [Cu—N = 2.0241 (9), 2.0374 (8) Å] and two chlorine atoms [Cu—Cl = 2.2500 (3), 2.2835 (3) Å]. The apical position is occupied by another Cl atom with the apical bond being significantly elongated at 2.6112 (3) Å. The trans angles of the base are 155.16 (3) and 173.79 (2)°. The Cu...Cu separation in the dimer is 3.4346 (3) Å. In the crystal structure, the loosely packed dimers are arranged in stacks propagating along the a axis. The X-band polycrystalline 77 K EPR spectrum of (I) demonstrates a typical axial pattern characteristic of mononuclear CuII complexes. Compound (I) is redox active and shows a cyclic voltammetric response with E1/2 = −0.037 V versus silver–silver chloride electrode (SSCE) assignable to the reduction peak of CuII/CuI in methanol as solvent.

The crystal structure of vanthoffite {hexasodium magnesium tetrakis[sulfate(VI)]}, Na6Mg(SO4)4, was solved in the year 1964 on a synthetic sample [Fischer & Hellner (1964). Acta Cryst. 17, 1613]. Here we report a redetermination of its crystal structure on a mineral sample with improved precision. It was refined in the space group P21/c from a crystal originating from Surtsey, Iceland. The unique Mg (site symmetry overline{1}) and the two S atoms are in usual, only slightly distorted octahedral and tetrahedral coordinations, respectively. The three independent Na atoms are in a distorted octahedral coordination (1×) and distorted 7-coordinations intermediate between a `split octahedron' and a pentagonal bipyramid (2×). [MgO6] coordination polyhedra interchange with one half of the sulfate tetrahedra in <011> chains forming a (100) meshed layer, with dimers formed by edge-sharing [NaO7] polyhedra filling the interchain spaces. The other [NaO7] polyhedra are organized in a parallel layer formed by [010] and [001] chains united through edge sharing and bonds to the remaining half of sulfate groups and to [NaO6] octahedra. The two types of layers interconnect through tight bonding, which explains the lack of morphological characteristics typical of layered structures.

In the structure of the title salt, (C7H12N6)[VOF5], second-order Jahn–Teller distortion of the coordination octahedra around V ions is reflected by coexistence of short V—O bonds [1.5767 (12) Å] and trans-positioned long V—F bonds [2.0981 (9) Å], with four equatorial V—F distances being intermediate in magnitude [1.7977 (9)–1.8913 (9) Å]. Hydrogen bonding of the anions is restricted to F-atom acceptors only, with particularly strong N–H...F interactions [N...F = 2.5072 (15) Å] established by axial and cis-positioned equatorial F atoms. Hirshfeld surface analysis indicates that the most important interactions are overwhelmingly H...F/F...H, accounting for 74.4 and 36.8% of the contacts for the individual anions and cations, respectively. Weak CH...F and CH...N bonds are essential for generation of three-dimensional structure.

In the first reported crystal structure involving the potential ligand N,N',N''-tris(pyridin-2-yl)benzene-1,3,5-tricarboxamide, C24H18N6O3, intermolecular N—H...O hydrogen bonds link the molecules via their amide groups into slanted ladder-like chains, in which the uprights of the ladder are formed by the hydrogen-bonding interactions and the benzene ring cores of the molecules act as the rungs of the ladder. Only two of the three amide groups in the molecule are involved in hydrogen bonding and this influences the degree of out-of-plane twisting at each amide group, with the twist being more significant for those amide groups participating in hydrogen bonds.

In small-molecule single-crystal structure determination, we now have at our disposal an inspiring range of fantastic diffractometers with better, brighter sources, and faster, more sensitive detectors. Faster and more powerful computers provide integrated tools and software with impressive graphical user interfaces. Yet these tools can lead to the temptation not to check the work thoroughly and one can too easily overlook tell-tale signs that something might be amiss in a structure determination; validation with checkCIF is not always revealing. This article aims to encourage practitioners, young and seasoned, by enhancing their structure-determination toolboxes with a selection tips and tricks on recognizing and handling aspects that one should constantly be aware of. Topics include a pitfall when setting up data collections, the usefulness of reciprocal lattice layer images, processing twinned data, tips for disorder modelling and the use of restraints, ensuring hydrogen atoms are added to a model correctly, validation beyond checkCIF, and the derivation and interpretation of the final results.

The crystal structure of tri­phenyl­methanol, C19H16O, has been redetermined using data collected at 295 and 153 K, and is compared to the model published by Ferguson et al. over 25 years ago [Ferguson et al. (1992). Acta Cryst. C48, 1272–1275] and that published by Serrano-González et al., using neutron and X-ray diffraction data [Serrano-González et al. (1999). J. Phys. Chem. B, 103, 6215–6223]. As predicted by these authors, the hy­droxy groups are involved in weak inter­molecular hydrogen bonds in the crystal, forming tetra­hedral tetra­­mers based on the two independent mol­ecules in the asymmetric unit, one of which is placed on the threefold symmetry axis of the Roverline{3} space group. However, the reliable determination of the hy­droxy H-atom positions is difficult to achieve, for two reasons. Firstly, a positional disorder affects the full asymmetric unit, which is split over two sets of positions, with occupancy factors of ca 0.74 and 0.26. Secondly, all hy­droxy H atoms are further disordered, either by symmetry, or through a positional disorder in the case of parts placed in general positions. We show that the correct description of the hydrogen-bonding scheme is possible only if diffraction data are collected at low temperature. The pro­chiral character of the hydrogen-bonded tetra­meric supra­molecular clusters leads to enanti­omorphic three-dimensional graphs in each tetra­mer. The crystal is thus a racemic mixture of supS and supR motifs, consistent with the centro­symmetric nature of the Roverline{3} space group.

Experimental electron-density studies based on high-resolution diffraction experiments allow halogen bonds between heavy halogens to be classified. The topological properties of the electron density in Cl⋯Cl contacts vary smoothly as a function of the inter­action distance. The situation is less straightforward for halogen bonds between iodine and small electronegative nucleophiles, such as nitro­gen or oxygen, where the electron density in the bond critical point does not simply increase for shorter distances. The number of successful charge–density studies involving iodine is small, but at least individual examples for three cases have been observed. (a) Very short halogen bonds between electron-rich nucleophiles and heavy halogen atoms resemble three-centre–four-electron bonds, with a rather symmetric heavy halogen and without an appreciable σ hole. (b) For a narrow inter­mediate range of halogen bonds, the asymmetric electronic situation for the heavy halogen with a pronounced σ hole leads to rather low electron density in the (3,−1) critical point of the halogen bond; the properties of this bond critical point cannot fully describe the nature of the associated inter­action. (c) For longer and presumably weaker contacts, the electron density in the halogen bond critical point is only to a minor extent reduced by the presence of the σ hole and hence may be higher than in the aforementioned case. In addition to the electron density and its derived properties, the halogen–carbon bond distance opposite to the σ hole and the Raman frequency for the associated vibration emerge as alternative criteria to gauge the halogen-bond strength. We find exceptionally long C—I distances for tetra­fluoro­diiodo­benzene molecules in cocrystals with short halogen bonds and a significant red shift for their Raman vibrations.

The enanti­opure monopyrrolidine derivative (2S)-methyl (Z)-5-(2-tert-but­oxy-1-cyano-2-oxo­ethyl­idene)pyrrolidine-2-carboxyl­ate, C13H18N2O4, (1), represents a potential ligand and an attractive inter­mediate for the synthesis of chiral metal com­plexes. At the mol­ecular level, the com­pound features an intra­molecular N—H⋯O hydrogen bond; neighbouring mol­ecules inter­act via N—H⋯N contacts to form chains along [100]. Due to its elemental com­position, resonant scattering of the target com­pound is entirely insignificant for diffraction experiments with Mo Kα and small even for Cu Kα radiation. A preliminary study with the harder radiation type confirmed the chiral space group and the suitability of the single crystal chosen; as expected, the results concerning the absolute structure remained com­pletely inconclusive. A second data collection with the longer wavelength gave satisfactory quality indicators for the correct handedness of the mol­ecule, albeit with high standard uncertainties. The absolute configuration has been assessed independently: CD spectra for both enanti­omers of the target mol­ecule were calculated and the spectrum for the S-configured stereoisomer was in agreement with the experiment. The Cotton effect of (1) may be ascribed to π–π* transitions from HOMO to LUMO and from HOMO to LUMO+1. As both independent techniques agree with respect to the handedness of the target mol­ecule, the absolute structure may be assigned with a high degree of confidence.

The title com­pound, tetra­ethyl­ammonium tetra­thio­rhenate, [(C2H5)4N][ReS4], has, at room temperature, a disordered structure in the space group P63mc (Z = 2, α-phase). A phase transition to the monoclinic space group P21 (Z = 2, γ-phase) at 285 K leads to a pseudo-merohedral twin. The high deviation from the hexa­gonal metric causes split reflections. However, the different orientations could not be separated, but were integrated using a large integration box. Rapid cooling to 110–170 K produces a metastable β-phase (P63, Z = 18) in addition to the γ-phase. All crystals of the β-phase are contaminated with the γ-phase. Additionally, the crystals of the β-phase are merohedrally twinned. In contrast to the α-phase, the β- and γ-phases do not show disorder.

During investigations of the formation of hydrated magnesium carbonates, a sample of the previously unknown magnesium carbonate hexa­hydrate (MgCO3·6H2O) was synthesized in an aqueous solution at 273.15 K. The crystal structure consists of edge-linked isolated pairs of Mg(CO3)(H2O)4 octa­hedra and noncoordinating water mol­ecules, and exhibits similarities to NiCO3·5.5H2O (hellyerite). The recorded X-ray diffraction pattern and the Raman spectra confirmed the formation of a new phase and its transformation to magnesium carbonate trihydrate (MgCO3·3H2O) at room temperature.

An error in an equation in the paper by Song et al. [Acta Cryst. (2019), C75, 1353–1358] is corrected.

An efficient synthesis of 1-aryl­isochromeno[3,4-d][1,2,3]triazol-5(1H)-ones, involving the diazo­tization of 3-amino-4-aryl­amino-1H-isochromen-1-ones in weakly acidic solution, has been developed and the spectroscopic characterization and crystal structures of four examples are reported. The mol­ecules of 1-phenyl­isochromeno[3,4-d][1,2,3]triazol-5(1H)-one, C15H9N3O2, (I), are linked into sheets by a combination of C—H⋯N and C—H⋯O hydrogen bonds, while the structures of 1-(2-methyl­phen­yl)isochromeno[3,4-d][1,2,3]triazol-5(1H)-one, C16H11N3O2, (II), and 1-(3-chloro­phen­yl)isochromeno[3,4-d][1,2,3]triazol-5(1H)-one, C15H8ClN3O2, (III), each contain just one hydrogen bond which links the mol­ecules into simple chains, which are further linked into sheets by π-stacking inter­actions in (II) but not in (III). In the structure of 1-(4-chloro­phen­yl)isochromeno[3,4-d][1,2,3]triazol-5(1H)-one, (IV), isomeric with (III), a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds links the mol­ecules into sheets. When com­pound (II) was exposed to a strong acid in methanol, qu­anti­tative conversion occurred to give the ring-opened transesterification product methyl 2-[4-hy­droxy-1-(2-methyl­phen­yl)-1H-1,2,3-triazol-5-yl]benzoate, C17H15N3O3, (V), where the mol­ecules are linked by paired O—H⋯O hydrogen bonds to form centrosymmetric dimers.

An operationally simple and time-efficient approach has been developed for the synthesis of racemic N-substituted 3-(2-aryl-2-oxoeth­yl)-3-hy­droxy­indolin-2-ones by a piperidine-catalysed aldol reaction between aryl methyl ketones and N-alkyl­isatins. These aldol products were used successfully as strategic inter­mediates for the preparation of N-substituted (E)-3-(2-hetaryl-2-oxo­ethyl­idene)indolin-2-ones by a stereoselective dehydration reaction under acidic conditions. The products have all been fully characterized by 1H and 13C NMR spectroscopy, by mass spectrometry and, for a representative selection, by crystal structure analysis. In each of (RS)-1-benzyl-3-hy­droxy-3-[2-(4-meth­oxy­phen­yl)-2-oxoeth­yl]indolin-2-one, C24H21NO4, (Ic), and (RS)-1-benzyl-3-{2-[4-(di­methyl­amino)­phen­yl]-2-oxoeth­yl}-3-hy­droxy­indolin-2-one, C25H24N2O3, (Id), inversion-related pairs of mol­ecules are linked by O—H⋯O hydrogen bonds to form R22(10) rings, which are further linked into chains of rings by a combination of C—H⋯O and C—H⋯π(arene) hydrogen bonds in (Ic) and by C—H⋯π(arene) hydrogen bonds in (Id). The mol­ecules of (RS)-1-benzyl-3-hy­droxy-3-[2-oxo-2-(pyridin-4-yl)eth­yl]indolin-2-one, C22H18N2O3, (Ie), are linked into a three-dimensional framework structure by a combination of O—H⋯N, C—H⋯O and C—H⋯π(arene) hydrogen bonds. (RS)-3-[2-(Benzo[d][1,3]dioxol-5-yl)-2-oxoeth­yl]-1-benzyl-3-hy­droxy­indolin-2-one, C24H19NO5, (If), crystallizes with Z' = 2 in the space group Poverline{1} and the mol­ecules are linked into com­plex sheets by a combination of O—H⋯O, C—H⋯O and C—H⋯π(arene) hydro­gen bonds. In each of (E)-1-benzyl-3-[2-(4-fluoro­phen­yl)-2-oxo­ethyl­idene]indolin-2-one, C23H16FNO2, (IIa), and (E)-1-benzyl-3-[2-oxo-2-(thiophen-2-yl)ethylidene]indolin-2-one, C21H15NO2S, (IIg), the mol­ecules are linked into simple chains by a single C—H⋯O hydrogen bond, while those of (E)-1-benzyl-3-[2-oxo-2-(pyridin-4-yl)ethyl­idene]indolin-2-one, C22H16N2O2, (IIe), are linked by three C—H⋯O hydrogen bonds to form sheets which are further linked into a three-dimensional structure by C—H⋯π(arene) hydrogen bonds. There are no hydrogen bonds in the structures of either (E)-1-benzyl-3-[2-(4-meth­oxy­phen­yl)-2-oxo­ethyl­idene]indolin-2-one, C24H19NO3, (IIc), or (E)-1-benzyl-5-chloro-3-[2-(4-chloro­phen­yl)-2-oxo­ethyl­idene]indolin-2-one, C23H15Cl2NO2, (IIh), but the mol­ecules of (IIh) are linked into chains of π-stacked dimers by a combination of C—Cl⋯π(arene) and aromatic π–π stacking inter­actions.

The com­pound poly[2-hy­droxy-N-methyl­ethan-1-aminium [μ3-cyanido-κ3C:C:N-di-μ-cyanido-κ4C:N-dicuprate(I)]], {(C3H10NO)[Cu2(CN)3]}n or [meoenH]Cu2(CN)3, crystallizes in the tetra­gonal space group P43. The structure consists of a three-dimensional (3D) anionic CuICN network with noncoordinated protonated N-methyl­ethano­lamine cations providing charge neutrality. Pairs of cuprophilic Cu atoms are bridged by the C atoms of μ3-cyanide ligands, which link these units into a 43 spiral along the c axis. The spirals are linked together into a 3D anionic network by the two other cyanide groups. The cationic moieties are linked into their own 43 spiral via N—H⋯O and O—H⋯O hydrogen bonds, and the cations inter­act with the 3D network via an unusual pair of N—H⋯N hydrogen bonds to one of the μ2-cyanide groups. Thermogravimetric analysis indicates an initial loss of the base cation and one cyanide as HCN at temperatures in the range 130–250 °C to form CuCN. We show how loss of a specific cyanide group from the 3D CuCN structure could form the linear CuCN structure. Further heating leaves a residue of elemental copper, isolated as the oxide.

Crystals of the rare earth metal polytelluride LaTe1.82(1), namely, lanthanum telluride (1/1.8), have been grown by molten alkali halide flux reactions and vapour-assisted crystallization with iodine. The two-dimensionally incommensurately modulated crystal structure has been investigated by X-ray diffraction experiments. In contrast to the tetra­gonal average structure with unit-cell dimensions of a = 4.4996 (5) and c = 9.179 (1) Å at 296 (1) K, which was solved and refined in the space group P4/nmm (No. 129), the satellite reflections are not compatible with a tetra­gonal symmetry but enforce a symmetry reduction. Possible space groups have been derived by group–subgroup relationships and by consideration of previous reports on similar rare earth metal polychalcogenide structures. Two structural models in the ortho­rhom­bic superspace group, i.e. Pmmn(α,β,1 over 2)000(−α,β,1 over 2)000 (No. 59.2.51.39) and Pm21n(α,β,1 over 2)000(−α,β,1 over 2)000 (No. 31.2.51.35), with modulation wave vectors q1 = αa* + βb* + 1 over 2c* and q2 = −αa* + βb* + 1 over 2c* [α = 0.272 (1) and β = 0.314 (1)], have been established and evaluated against each other. The modulation describes the distribution of defects in the planar [Te] layer, coupled to a displacive modulation due to the formation of different Te anions. The bonding situation in the planar [Te] layer and the different Te anion species have been investigated by density functional theory (DFT) methods and an electron localizability indicator (ELI-D)-based bonding analysis on three different approximants. The temperature-dependent electrical resistance revealed a semiconducting behaviour with an estimated band gap of 0.17 eV.

During evaporation of natural and synthetic K–Mg–Cl brines, the formation of almost square plate-like crystals of potassium carnallite (potassium chloride magnesium dichloride hexa­hydrate) was observed. A single-crystal structure analysis revealed a monoclinic cell [a = 9.251 (2), b = 9.516 (2), c = 13.217 (4) Å, β = 90.06 (2)° and space group C2/c]. The structure is isomorphous with other carnallite-type com­pounds, such as NH4Cl·MgCl2·6H2O. Until now, natural and synthetic carnallite, KCl·MgCl2·6H2O, was only known in its ortho­rhom­bic form [a = 16.0780 (3), b = 22.3850 (5), c = 9.5422 (2) Å and space group Pnna].

A new polymorph (form II) is reported for the 1:1 dimethyl sulfoxide solvate of 2,3,5,6-tetra­fluoro-1,4-di­iodo­benzene (TFDIB·DMSO or C6F4I2·C2H6SO). The structure is similar to that of a previously reported polymorph (form I) [Britton (2003). Acta Cryst. E59, o1332–o1333], containing layers of TFDIB mol­ecules with DMSO mol­ecules between, accepting I⋯O halogen bonds from two TFDIB mol­ecules. Re-examination of form I over the temperature range 300–120 K shows that it undergoes a phase transformation around 220 K, where the DMSO mol­ecules undergo re-orientation and become ordered. The unit cell expands by ca 0.5 Å along the c axis and contracts by ca 1.0 Å along the a axis, and the space-group symmetry is reduced from Pnma to P212121. Refinement of form I against data collected at 220 K captures the (average) structure of the crystal prior to the phase transformation, with the DMSO mol­ecules showing four distinct disorder com­ponents, corresponding to an overlay of the 297 and 120 K structures. Assessment of the inter­molecular inter­action energies using the PIXEL method indicates that the various orientations of the DMSO mol­ecules have very similar total inter­action energies with the molecules of the TFDIB framework. The phase transformation is driven by inter­actions between DMSO mol­ecules, whereby re-orientation at lower temperature yields significantly closer and more stabilizing inter­actions between neighbouring DMSO mol­ecules, which lock in an ordered arrangement along the shortened a axis.

The covers to the last issues of the current runs of "Avengers" and "New Avengers," leading into "Secret Wars."; Credit: Marvel

Marvel Comics held a press conference this week announcing details about "Secret Wars," a company-wide comic book crossover that they promise will change everything.

Promises of change in comics often don't amount to much, but here's why this one just might, with Marvel teasing that it will produce a whole new world for its characters.

"We see this as putting an endcap to decades of stories and starting a new era," said Marvel Editor-in-Chief Axel Alonso. "And when you see the scope of the event, you see what we're doing, what we're willing to do, this is a place where we're going to be bringing new pieces onto the board and taking old pieces off. You guys will be yelling and screaming, you'll be loving, hating, and in equal measure."

Reboot history

Rival DC Comics has always been quick to have stories designed to streamline their history, with the "Crisis on Infinite Earths" being the most famous one — a story that destroyed the DC Comics universe of the time, birthing a new timeline that gave us the versions of DC's heroes we know today. Several minor and major reboots followed, with the biggest since then being 2011's New 52 (and a tease of another one with this April's "Convergence").

Meanwhile, Marvel still refers back to stories from their early days, beginning with the first issue of "Marvel Comics" in 1939, and more so since the launch of "Fantastic Four" and the interlinked Marvel Universe in the 1960s, led by Stan Lee and Jack Kirby.

Marvel previously launched a line of comics meant to offer a fresh vision of the Marvel characters called Ultimate Comics, but now the worlds of those characters and the traditional Marvel universe are getting combined thanks to "Secret Wars."

"The Ultimate Universe, the Marvel Universe, they're going to smash together," said Alonso. "This is the Marvel Universe moving forward."

"We've never done anything like this, ever," said Marvel senior vice president and executive editor Tom Brevoort. "And what we're going to do to top it, I don't know. Hopefully that will be somebody else's problem."

The stories leading to "Secret Wars," and what is Battleworld?

The story that's been built up so far has to do with different universes colliding into each other — and in the first issue of "Secret Wars," the Marvel and Ultimate Earths collide, with the heroes of those worlds unable to stop it. What's left behind is what Marvel is calling "Battleworld," a patchwork planet with different parts of it inhabited by the characters from different famous Marvel crossovers of the past (you can see some of those past titles in the slideshow above).

Marvel released this video to help you visualize what exactly Battleworld is:

Battleworld video

See a map of Battleworld here, showing the different worlds made up of old storylines to be explored in "Secret Wars" (and click to enlarge):

Brevoort described Battleworld as "The little melting pot in which the new Marvel Universe will be created" after the Marvel and Ultimate versions of Earth are destroyed. He said that Battleworld is what Marvel is going to be "during, through and after" the beginning of "Secret Wars."

"Once you hit 'Secret Wars' 1, there is no Marvel Universe. There is no Ultimate Universe. All there is is Battleworld, and a whole lot of empty void," Brevoort said.

"Every single piece of this world is a building block for the Marvel Universe moving forward," Alonso said. "None of these stories are Elseworlds, or What Ifs, or alternative reality stories. They aren't set in the past or the future. They're not set in an alternate reality. They're set in the reality of the Marvel Universe."

It's also a story that uses an old name — the original "Secret Wars" involved an alien taking heroes from Earth and forcing them into battle for the fate of the universe. It remains unclear if the villain from that crossover will play a role here.

Why is Marvel rebooting?

Observers were quick to speculate on some of the behind-the-scenes reasons for the change. Combining the Ultimate Universe with the traditional Marvel Universe would let them incorporate the half-black, half-Latino Spider-Man from the Ultimate line that grabbed headlines a few years ago. It would let them do something different with characters like the X-Men and the Fantastic Four, who have been a flashpoint for controversy due to Fox retaining rights in perpetuity to any films based on those characters.

It also opens the door to a longtime comic book trope: Bringing back to life the dead.

"If we were to want to resurrect Gwen Stacy, this would be the place to do it, wouldn't it?" Alonso said.

What do creators and fans think about "Secret Wars"?

Speaking of the death of Gwen Stacy, the writer who pulled the trigger on killing her, Gerry Conway, tells Newsarama that he's on board.

"I think like with any idea, the execution will matter more than the idea itself. The idea of a reset is, by itself, not a bad idea," Conway said.

One who's less on board with it: longtime Spider-Man artist John Romita.

"My guess is new fans will be okay with it, and old fans will grumble," Romita told Newsarama. "I’m not a businessman, but I do know that comic companies, for almost 100 years now, do whatever they can for shock value. They grab attention. Personally, I hate all the goofy things they do. When I was there, I used to fight stuff like this. But you can’t stop them."

Current Marvel writers have been sworn to secrecy about what happens once "Secret Wars" is done:

Dan Slott tweet

The lack of certainty about what this all means has led fans to wildly speculate, as well as poke fun at what might happen:

Fan tweet 1

Fan tweet 2

It's a story that's been years in the making.

"Every single time we've done an event, we've always had to be mindful of 'Secret Wars,' and we've had to make decisions based on the fact that we knew that 'Secret Wars' was headed our way," Alonso said.

Brevoort said that Hickman proposed a version of "Secret Wars" years ago, but that vision has since become significantly larger.

"It sounds like typical Stan lee hyperbole — and there's nothing wrong with typical Stan Lee hyperbole — but it is difficult to imagine something that would be larger in scope, in scale, than what we are doing with 'Secret Wars,'" Brevoort said.

That father of the modern Marvel comics world, Stan Lee, tells Newsarama that the reboot is "probably good."

"Anything they do that’s unexpected and different usually captures the attention of the fans," Lee said. "It sounds intriguing to me."

Lee also tells Newsarama that if he were to do it all again, he'd do it basically the same, describing what he did as "the right way to go, and maybe sometimes, even the perfect way to go."

"I liked making the Fantastic Four superheroes without a secret identity. I liked the tragedy of Spider-Man’s origin, the ‘with great power, there must also come great responsibility.’ I thought it was the right way of doing things at the time. And I still like what I’ve done," Lee said. "I can’t think, off the top of my head, of anything I’d really want to change."

What does "Secret Wars" mean for fans?

More details are promised in the weeks to come, with a free preview issue being released on Free Comic Book Day, May 2. While fans wait, they may want to heed the wait-and-see approach advocated by Conway and famed "Thor" artist Walt Simonson.

"Maybe this is coming back out of my old geology days, but I try not to have instant reactions to things and say, ‘Oh my God! That’s terrible!’" Simonson told Newsarama. "My basic reaction is usually ‘let’s see the evidence in the field.’ Let’s come back in a year and see what we’ve got. That will tell the story.”

And for those who say that Marvel is ruining their childhood by messing with the history of their favorite characters, Conway tells Newsarama:

"I would say to them, no, your childhood is still your childhood. There’s a point to be made, and it’s a universal one: We have to see that there’s a difference between what people do today, and what they did yesterday. Yesterday still exists, those stories still exist. Now someone else is getting a chance at a new childhood. And that’s nice."

Watch the full "Secret Wars" live press conference below:

Secret Wars press conference video

This content is from Southern California Public Radio. View the original story at SCPR.org.

An image from a teaser for Marvel Comics' 2015 "Civil War," part of crossover "Secret Wars." Could Spidey appear in the new Captain America: Civil War film now that Marvel and Sony have worked out a deal?; Credit: Marvel

Spider-Man is coming home to join the rest of the Marvel movie family (um, except for the Fantastic Four and the X-Men) in upcoming films under a new deal struck between Sony, the home for Spider-Man movies, and Disney's Marvel Studios, home of Iron Man and the Avengers

It's been a bumpy road for Spidey for almost a decade, but now he's set to be part of the largely critically and financially successful Marvel Cinematic Universe films. He's already made history, and he could make more history soon. 

Here's a brief history of cinematic Spider-Man, looking ahead to his new adventures with Marvel's large and growing stable of movie superheroes.

Coming out of the superhero dark ages

Spider-Man was one of the catalysts for the current superhero movie boom. Superhero films were seen as potentially dead following the bomb of "Batman & Robin" with George Clooney, a critical failure and a mixed bag commercially.

Marvel dipped its toes in superhero movies with 1998's "Blade," which was a big hit, followed by 2000's "X-Men," but they both tried to distance themselves from their comic book source material (and the Joel Schumacher Batman movies) by putting their heroes in black leather and grounding them as much as possible in real-life aesthetics.

Sony's first "Spider-Man" movie came out in 2002 and showed that there was still room for an optimistic comic book take. The Sam Raimi-directed film also had a huge cultural impact as one of the first big summer movies following 9/11 — an early teaser that showed Spidey trapping bad guys between the two towers had to be pulled following the disaster.

Spider-Man 9/11 trailer

The movie ended up pulling in almost $822 million at the box office, including almost $404 million domestically, helmed by genre director Raimi, who had previously been best known for the horror-comedy "Evil Dead" films.

Spider-Man trailer

Tobey Maguire surprised as the star, pulling off the nerdy, earnest Peter Parker while also being believable enough as an action star in the Spider-Man suit. Maguire starred alongside Kirsten Dunst as love interest Mary Jane and Willem Dafoe as the villainous Green Goblin, and the film included the not-yet-a-superstar James Franco as Harry Osborn and now-Oscar-nominated J.K. Simmons as Daily Bugle publisher J. Jonah Jameson.

A sequel, 2004's "Spider-Man 2," continued the success of the first, with only a slight dip in overall box office while proving that the first film's success wasn't just a flash in the pan, that there was room for a relatively bright superhero in a dark time.

Spider-Man 2 trailer

Maguire almost ducked out of filming during negotiations, complaining of back pains following injuries while filming "Seabiscuit," and Jake Gyllenhaal almost stepped into the role — but Maguire recovered and held onto his spot. The escapist entertainment of superhero movies was starting to take hold in a growing way, but the superhero train was about to come off the rails for a few years.

The twilight of Tobey Maguire

As "Spider-Man 2" was hitting theaters, 2004 also brought "The Punisher," "Blade: Trinity" and "Catwoman," none of which showed superheroes as particularly promising movie saviors.

Marvel turned out more superhero movies that weren't loved by critics, including "Elektra," "Fantastic Four" and "X-Men: The Last Stand," though the latter two still did well at the box office (all were released by 20th Century Fox). DC Comics made the critical and commercial hit "Batman Begins" in 2005, but stumbled in 2006 with the underperforming "Superman Returns."

In 2007, "Spider-Man 3" dropped, and while it did great at the box office — it was the series' most popular film worldwide, though it dipped domestically — it was slammed by fans and critics. They took that Spider-Man optimism and tried making him emo, while overstuffing the bad guys — going from one villain in the previous films and upping it to three — and turning the campy dialogue up to 11.

Spider-Man 3 trailer

Trying to be 'Amazing' in a new superhero era

While Spidey stumbled, the next year Marvel released its first film from its own studio, the groundbreaking "Iron Man." It showed that you could make a franchise from a hero who was big in the comics but didn't have the same mainstream recognition.

It revitalized Robert Downey Jr.'s career and put Marvel Studios on the map, with a post-credits sequence laying the seeds for completely tying the films together in a way that hadn't been done on this scale ever before.

While Marvel started to crank up their self-produced film, Spider-Man lay dormant. Eventually, it was decided to reboot the character with Andrew Garfield taking over the role in 2012's "The Amazing Spider-Man." It scored the lowest domestic take of the series, while still excelling overseas.

Amazing Spider-Man 2 trailer 1

Sony quickly followed up with a sequel, while announcing their own plans to ape Marvel and try to create their own cinematic universe.

Amazing Spider-Man 2 villains trailer

The second "Amazing Spider-Man" movie set up other potential villains, and holding off the payoff of what exactly happened to Peter Parker's parents as Marvel tried to stretch Spider-Man into a female-led film, one focused on the villains, a movie led by Spidey character Venom and more.

Amazing Spider-Man first 10 minutes

The sequel showed diminishing returns, though, and plans for further sequels and spinoffs began to seem up in the air.

Hacked

In the midst of the Sony hack, documents revealed that Sony and Marvel had been negotiating over Marvel using Spider-Man in its own films — despite Sony having the rights to the character in perpetuity as long as they kept producing films, a deal worked out before Marvel had the resources and the belief in their own filmmaking capabilities. Still, the documents also showed that the talks had fallen apart, and hopes for Spider-Man appearing with Iron Man, Captain America, Thor and the rest of his Marvel friends appeared dim.

Then, Monday, Marvel shocked everyone by announcing that Spider-Man was coming home and would be part of the Marvel Cinematic Universe after all. There had been reports that they'd wanted Spider-Man for the third Captain America film, and with that film set for 2016, that may still happen. They also pushed back four of their "Phase Three" movies to make room in 2017 for a new "Spider-Man" movie, with reports indicating that the movie will feature a new actor taking over and Andrew Garfield getting pushed aside.

Spider-Man comes home

Andrew Garfield will likely go down in comics movie history as the right guy at the wrong time. He was a likable lead with a strong supporting cast, but Marvel looks ready to turn the page. Those on the Marvel side have previously indicated they'd avoid doing another origin story, so we'll probably skip seeing Uncle Ben killed to inspire Peter Parker once again.

"The new relationship follows a decade of speculation among fans about whether Spider-Man – who has always been an integral and important part of the larger Marvel Universe in the comic books – could become part of the Marvel Universe on the big screen," Marvel said in the announcement of the new deal.

Fans online have been largely ecstatic over the announcement of Marvel getting control of the character. Reports indicate that Sony still gets final say over Spider-Man, but that they're letting Marvel take the creative lead. Marvel also announced the possibility that other Marvel characters could appear in future Spider-Man films.

While Sony's Amy Pascal stepped down as the motion picture head of Sony following the hacking scandal and its associated public embarrassments, she's staying on as a producer — including co-producing the next Spider-Man film with Marvel creative film leader Kevin Feige.

Some fans have also asked for an even bigger step away from the traditional Spider-Man by introducing Miles Morales, the popular half-black/half-hispanic Spider-Man from an alternate universe in the comics, but the official Marvel press release does mention Peter Parker, and Marvel executives have previously taken a strong stance against moving away from Parker as the secret identity.

Still, as Badass Digest's Devin Faraci notes, the executive who'd taken the strongest stance against Miles Morales — Avi Arad — isn't mentioned in the press release about the new film, so maybe Marvel will surprise fans once again. Also, relations have apparently been icier between Marvel and Fox, with fans speculating that Marvel is trying to ice out the X-Men and the Fantastic Four from their comics — but if the companies could work out a deal to use those heroes in a Marvel Cinematic Universe film, it could prove to be an even bigger surprise.

The new Spider-Man film is set for July 28, 2017, and he may appear in another Marvel film sooner.

This content is from Southern California Public Radio. View the original story at SCPR.org.

Jerry "The King" Lawler with Jim Ross.; Credit: WWE

Jim Ross is the most famous pro wrestling play-by play commentator of all time. He's a native Californian, but grew up in Oklahoma and took his trademark drawl into doing commentary. He's worked in wrestling for more than 40 years, calling matches on shows seen by millions of people around the world.

This weekend, he's in the Bay Area for Wrestlemania weekend (the first Wrestlemania in Northern California, and the first in California in 10 years). Ross no longer commentates for WWE, but he's still a storyteller, online and in person. He hosts regular live storytelling shows with stories from his decades-long career and a bit of comedy, along with a live guest, and he also has a huge online presence including a podcast that went to number one in sports its first week out.

Ross has been watching wrestling since he was a kid.

"My dad wasn't a big fan of it. He missed the point. The point is not whether it's real or if it's staged. The point is, are you entertained by it, or not? And I was," Ross said.

He's been at ringside for numerous historic matches, helping the wrestlers to tell their stories ever since he got his first job in wrestling out of college at 22.

"The greater the star, the easier it is to tell their story," Ross said. "Those participants make music. They make different kinds of music, and the announcers, the broadcasters, have to be able to provide the adequate lyric to the competitors' music."

Ross's voice is so powerful that it's become a meme online to pair his voice with another dramatic footage, from sports and beyond — you can even find it paired with dramatic moments from shows like "Breaking Bad" and "Game of Thrones." Ross says that the first time he saw someone do that was with a hit by Michigan running back Jadaveon Clowney, a video which went viral and sparked others to do likewise.

The JR Treatment

"I get sent these memes all the time. 'Hey JR, check this one out.' Or people will say, somebody will make a great dunk at an NBA game, and somebody will say 'I can't wait to see this get the JR treatment.' And now there are major sports websites that will send out a tweet, 'Here's a great play from Sunday's 49er-Charger game that's got the JR treatment.' So now it's got a name. 'The JR Treatment.'"

Those viral videos have even helped him land new commentating roles since leaving WWE. He did a call of a fight between NASCAR drivers for the Daytona 500 for a special pre-show video, and it's led to him having opportunities in traditional sports.

"It's been done in boxing, and MMA. Believe it or not, I've gotten feelers that we're entertaining now from a variety of combat sports entities that actually heard what my call would sound like doing their product," Ross said. "It had my tone, had my inflection, had my level of enthusiasm."

Ross also played a huge role behind the scenes, working as WWE's executive vice president of talent and signing future stars like the Rock, Mick Foley and more. He says that Mick Foley's match against the Undertaker in 1998's Hell in a Cell match was his most memorable to call.

"I have people walk up to me and start quoting my commentary when Undertaker threw Foley off the Hell in a Cell, this massive cage with a roof on it, that was about 17 feet high from the roof to the floor," Ross said. "It looked like no human being, quite honestly, could survive that fall. You don't practice falls like that in wrestling school."

Ross has managed to stay relevant with the help of a popular podcast and 1.3 million followers on Twitter, where he regularly dispenses his thoughts on wrestling and beyond. He started doing that podcast after being lobbied to do it by "Stone Cold" Steve Austin, and continues to try new things.

"I was very reluctant to engage in social media, and primarily because we sometimes get set in our ways, especially the older we get," Ross said. "But change, for any of us, in any walk of life, whether it's your diet, it's your relationships, the way you approach your job, or any changes that you need to affect, whether it's on doctor's orders, your significant other's suggestions — change is not always a negative thing. So I got on Twitter, and then Twitter connected me to so many people."

While some may feel that pro wrestling, given its predetermined results, doesn't need real athletes, Ross disagrees and says there are plenty of reasons to want real athletes.

"They're competitive. They don't want to be on the second team. They want to be in the game. And they've been in that mindset since some of them were in little league, or Pop Warner football, or elementary school wrestling, or whatever it may be."

He says they also understand how to be coached and how to play well with others, as well as handling the bumps and bruises that come with the territory and the difficult travel schedule.

"I don't know that anybody in any entity, unless you're the most well-traveled comedian or entertainer, has that. Because the thing about pro wrestling is it doesn't have an off-season, so you don't get a chance to really go recharge your batteries. You've got to maintain that competitive edge to survive."

Ross says there's one match he wishes he had another shot at calling: Ric Flair's retirement match against Shawn Michaels at Wrestlemania 24 in Orlando at the Citrus Bowl. While Ross has traditionally been a play-by-play commentator, that night he was assigned to be a color commentator, which gave him some different challenges.

"I thought I had great stories to tell because of my relationship with Ric — I've known him for 25 years — and I didn't think that I contributed as much to that match from an emotional standpoint as I could. I was obligated to get in soundbites and get in, get out," Ross said. "That's the biggest match at the biggest stage, and I love both those guys, and I really wanted to be extra special that night, and I just don't know in my heart that we got there."

He says California has its own wrestling legacy to be proud of. The California Wrestlemania match that Ross says he'll always remember: Bret Hart versus Shawn Michaels at Wrestlemania 12 in Anaheim, where two now wrestling legends wrestled for more than an hour.

He also thinks the economics of Wrestlemania make a lot of sense for whichever city hosts it, thanks to the travelers it draws in from around the world. Cities now bid to try to bring in Wrestlemania, Ross says. With Los Angeles gearing up to build a new stadium, Ross has a Wrestlemania prediction for that stadium.

"I will bet you money — I will bet you some of my barbecue sauce — if L.A. builds a stadium, that Wrestlemania will be one of the first non-football events in that stadium. And they will sell it out. They'll fill every seat. And it'll be great for the city, and the businesses of Los Angeles.

Ross says that what made him a great broadcaster is the same thing that can make someone a success in wrestling or anywhere else — most importantly, don't talk down to your audience.

"You have to be a fan of the genre, or a fan of the game, and you have to be willing to prepare and be ready for your broadcast," Ross said. "You have to be willing to tell the story that the average fan — not the hardcore fan, but the average, casual fan can understand and relate to. ... You know, we're storytellers, and some people are just natural-born storytellers."

Ross plans to continue telling stories for the foreseeable future, on stage, online, calling matches in the legit sports world and wherever else his life takes him. He's even gotten into acting — you can see him in the new film "What Now."

"I think retirement is overblown. How many days can you go fishing? How many rounds of golf can you play?" Ross said. "I had the idea when I left WWE after 21 years, I'm going to reinvent myself. I'm not going to become a trivia answer. ... I don't think you're going to read anywhere, anytime soon, that Jim Ross has finally retired — until you read my eulogy."

Listen to the audio for the full hour-long interview with Jim Ross, talking his career past, present and future — along with the origins of his signature barbecue sauce.

This content is from Southern California Public Radio. View the original story at SCPR.org.

The application of groupoids to modular crystal structures is presented.

Features of azimuthal plots for RHEED and its new counterpart, RHEPD, are discussed. The plots, for both electrons and positrons, are determined using dynamical diffraction theory.

A method is described for indexing grazing-incidence X-ray diffraction data of epitaxially grown thin films comprising various crystal orientations and/or polymorphs by measuring reciprocal-lattice vectors.

A method is adapted to generate a full rank realization of an abstract regular polyhedron with automorphism group H3.

Structure-mining finds and returns the best-fit structures from structural databases given a measured pair distribution function data set. Using databases and heuristics for automation it has the potential to save experimenters a large amount of time as they explore candidate structures from the literature.

Physical quantities in arbitrary dimensional space can be classified into 41 types using three antisymmetries within the framework of Clifford algebra.

A new type of X-ray LLL interferometer, a `hard' interferometer, which has both a base and a `ceiling', is tested for experimental investigations. The tested interferometer has no preliminary uncontrollable moiré and can be used for object and deformation investigations.