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RTC bus from Vizag delivers TB medicinesin Anantapur

While Andhra Pradesh Road Transport Corporation(APSRTC) is transporting essential goods like rice, vegetables and fruits within the State, it has also




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This week's sponsor: WEBEDITION

WEBEDITION, the best way to craft and deliver issues of your own online magazine. Start now and build an issue for free.




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Taiwan Dragons vs Taiwan Daredevils, Dream11 Prediction: Best picks for TDG vs TDR today in Taipei T10 League

TDG vs TDR Dream11 Team - Check My Dream11 Team, Best players list of today's match, Taiwan Dragons vs Taiwan Daredevils Dream11 Team Player List, TDG Dream11 Team Player List, TDR Dream11 Team Player List, Dream11 Guru Tips, Online Cricket Tips, Taiwan Dragons vs Taiwan Daredevils Head to Head.




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Hsinchu Titans vs Taiwan Daredevils, Dream11 Prediction: Best picks for HST vs TDR today in Taipei T10 League

HST vs TDR Dream11 Team - Check My Dream11 Team, Best players list of today's match, Hsinchu Titans vs Taiwan Daredevils Dream11 Team Player List, TDG Dream11 Team Player List, HST Dream11 Team Player List, Dream11 Guru Tips, Online Cricket Tips, Hsinchu Titans vs Taiwan Daredevils Head to Head.




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Ayurveda medicine trial to begin on asymptomatic Covid-19 patients in Chandigarh




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IRIXS: a resonant inelastic X-ray scattering instrument dedicated to X-rays in the intermediate energy range

A new resonant inelastic X-ray scattering (RIXS) instrument has been constructed at beamline P01 of the PETRA III synchrotron. This instrument has been named IRIXS (intermediate X-ray energy RIXS) and is dedicated to X-rays in the tender-energy regime (2.5–3.5 keV). The range covers the L2,3 absorption edges of many of the 4d elements (Mo, Tc, Ru, Rh, Pd and Ag), offering a unique opportunity to study their low-energy magnetic and charge excitations. The IRIXS instrument is currently operating at the Ru L3-edge (2840 eV) but can be extended to the other 4d elements using the existing concept. The incoming photons are monochromated with a four-bounce Si(111) monochromator, while the energy analysis of the outgoing photons is performed by a diced spherical crystal analyzer featuring (102) lattice planes of quartz (SiO2). A total resolution of 100 meV (full width at half-maximum) has been achieved at the Ru L3-edge, a number that is in excellent agreement with ray-tracing simulations.




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Foreword to the special virtual issue dedicated to the proceedings of the PhotonDiag2018 workshop on FEL Photon Diagnostics, Instrumentation, and Beamlines Design




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Contributions of charge-density research to medicinal chemistry

Contributions of experimental and selected theoretical charge-density research to medicinal chemistry are reviewed; combining experimental methods from high-resolution small-molecule and macromolecular crystallography with theory proves to be fruitful.






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2,2'-[Methyl­enebis(sulfanedi­yl)]bis­(pyridine 1-oxide)

The title compound, C11H10N2O2S2, crystallizes with one complete mol­ecule in the asymmetric unit. In the crystal, weak hydrogen bonding is observed between the N-oxide moieties and several C—H units.




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Crystal structure of pirfenidone (5-methyl-1-phenyl-1H-pyridin-2-one): an active pharmaceutical ingredient (API)

The crystal structure of pirfenidone, C12H11NO [alternative name: 5-methyl-1-phenyl­pyridin-2(1H)-one], an active pharmaceutical ingredient (API) approved in Europe and Japan for the treatment of Idiopathic pulmonary fibrosis (IPF), is reported here for the first time. It was crystallized from toluene by the temperature gradient technique, and crystallizes in the chiral monoclinic space group P21. The phenyl and pyridone rings are inclined to each other by 50.30 (11)°. In the crystal, mol­ecules are linked by C–H⋯O hydrogen bonds involving the same acceptor atom, forming undulating layers lying parallel to the ab plane.




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Crystal structure of (15,20-bis­(2,3,4,5,6-penta­fluoro­phen­yl)-5,10-{(4-methyl­pyridine-3,5-di­yl)bis­[(sulfanediyl­methyl­ene)[1,1'-biphen­yl]-4',2-di­yl]}porphyrinato)nickel(II) di­chloro

The title compound, [Ni(C64H33F10N5S2)]·xCH2Cl2, consists of discrete NiII porphyrin complexes, in which the five-coordinate NiII cations are in a distorted square-pyramidal coordination geometry. The four porphyrin nitro­gen atoms are located in the basal plane of the pyramid, whereas the pyridine N atom is in the apical position. The porphyrin plane is strongly distorted and the NiII cation is located above this plane by 0.241 (3) Å and shifted in the direction of the coordinating pyridine nitro­gen atom. The pyridine ring is not perpendicular to the N4 plane of the porphyrin moiety, as observed for related compounds. In the crystal, the complexes are linked via weak C—H⋯F hydrogen bonds into zigzag chains propagating in the [001] direction. Within this arrangement cavities are formed, in which highly disordered di­chloro­methane solvate mol­ecules are located. No reasonable structural model could be found to describe this disorder and therefore the contribution of the solvent to the electron density was removed using the SQUEEZE option in PLATON [Spek (2015). Acta Cryst. C71, 9–18].




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Different packing motifs mediated by weak inter­actions and polymorphism in the crystal structures of five 2-(benzyl­idene)benzosuberone derivatives

The syntheses and crystal structures of five 2-benzyl­idene-1-benzosuberone [1-benzosuberone is 6,7,8,9-tetra­hydro-5H-benzo[7]annulen-5-one] derivatives, viz. 2-(4-meth­oxy­benzyl­idene)-1-benzosuberone, C19H18O2, (I), 2-(4-eth­oxy­benzyl­idene)-1-benzosuberone, C20H20O2, (II), 2-(4-benzyl­benzyl­idene)-1-benzosuberone, C25H22O2, (III), 2-(4-chloro­benzyl­idene)-1-benzosuberone, C18H15ClO, (IV) and 2-(4-cyano­benzyl­idene)-1-benzosuberone, C19H15NO, (V), are described. The conformations of the benzosuberone fused six- plus seven-membered ring fragments are very similar in each case, but the dihedral angles between the fused benzene ring and the pendant benzene ring differ somewhat, with values of 23.79 (3) for (I), 24.60 (4) for (II), 33.72 (4) for (III), 29.93 (8) for (IV) and 21.81 (7)° for (V). Key features of the packing include pairwise C—H⋯O hydrogen bonds for (II) and (IV), and pairwise C—H⋯N hydrogen bonds for (V), which generate inversion dimers in each case. The packing for (I) and (III) feature C—H⋯O hydrogen bonds, which lead to [010] and [100] chains, respectively. Weak C—H⋯π inter­actions consolidate the structures and weak aromatic π–π stacking is seen in (II) [centroid–centroid separation = 3.8414 (7) Å] and (III) [3.9475 (7) Å]. A polymorph of (I) crystallized from a different solvent has been reported previously [Dimmock et al. (1999) J. Med. Chem. 42, 1358–1366] in the same space group but with a packing motif based on inversion dimers resembling that seen in (IV) in the present study. The Hirshfeld surfaces and fingerprint plots for (I) and its polymorph are com­pared and structural features of the 2-benzyl­idene-1-benzosuberone family of phases are surveyed.




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(μ-Di-tert-butyl­silanediolato)bis­[bis­(η5-cyclo­penta­dien­yl)methyl­zirconium]

The reaction of t-Bu2Si(OH)2 with two equivalents of Cp2Zr(CH3)2 produces the title t-Bu2SiO2-siloxide bridged dimer, [Zr2(CH3)2(C5H5)4(C8H18O2Si)] or [Cp2Zr(CH3)]2[μ-t-Bu2SiO2] (1), where one methyl group is retained per zirconium atom. The same product is obtained at room temperature even when equimolar ratios of the silanediol and Cp2Zr(CH3)2 are used. Attempts to thermally eliminate methane and produce a bridging methyl­ene complex resulted in decomposition. The crystal structure of 1 displays typical Zr—CH3 and Zr—O distances but the Si—O distance [1.628 (2) Å] and O—Si—O angle [110.86 (15)°] are among the largest observed in this family of compounds suggesting steric crowding between the t-Bu substituents of the silicon atom and the cyclo­penta­dienyl groups. The silicon atom lies on a crystallographic twofold axis and both Cp rings are disordered over two orientations of equal occupancy.




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N,N'-Bis(pyridin-3-ylmeth­yl)ethanedi­amide monohydrate: crystal structure, Hirshfeld surface analysis and computational study

The mol­ecular structure of the title bis-pyridyl substituted di­amide hydrate, C14H14N4O2·H2O, features a central C2N2O2 residue (r.m.s. deviation = 0.0205 Å) linked at each end to 3-pyridyl rings through methyl­ene groups. The pyridyl rings lie to the same side of the plane, i.e. have a syn-periplanar relationship, and form dihedral angles of 59.71 (6) and 68.42 (6)° with the central plane. An almost orthogonal relationship between the pyridyl rings is indicated by the dihedral angle between them [87.86 (5)°]. Owing to an anti disposition between the carbonyl-O atoms in the core, two intra­molecular amide-N—H⋯O(carbon­yl) hydrogen bonds are formed, each closing an S(5) loop. Supra­molecular tapes are formed in the crystal via amide-N—H⋯O(carbon­yl) hydrogen bonds and ten-membered {⋯HNC2O}2 synthons. Two symmetry-related tapes are linked by a helical chain of hydrogen-bonded water mol­ecules via water-O—H⋯N(pyrid­yl) hydrogen bonds. The resulting aggregate is parallel to the b-axis direction. Links between these, via methyl­ene-C—H⋯O(water) and methyl­ene-C—H⋯π(pyrid­yl) inter­actions, give rise to a layer parallel to (10overline{1}); the layers stack without directional inter­actions between them. The analysis of the Hirshfeld surfaces point to the importance of the specified hydrogen-bonding inter­actions, and to the significant influence of the water mol­ecule of crystallization upon the mol­ecular packing. The analysis also indicates the contribution of methyl­ene-C—H⋯O(carbon­yl) and pyridyl-C—H⋯C(carbon­yl) contacts to the stability of the inter-layer region. The calculated inter­action energies are consistent with importance of significant electrostatic attractions in the crystal.




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Crystal structure and Hirshfeld surface analysis of a copper(II) complex with ethyl­enedi­amine and non-coordinated benzoate

In the title compound, di­aqua­bis­(ethyl­enedi­amine-κ2N,N')copper(II) bis­(2-nitro­benzoate), [Cu(C2H8N2)2(H2O)2](C7H4NO4)2, two di­aqua­bis­(ethyl­enedi­amine)­copper(II) cations and four nitro­benzoate anions are present in the asymmetric unit. All four anions are `whole-mol­ecule' disordered over two sets of sites. The major components have refined occupancies of 0.572 (13), 0.591 (9), 0.601 (9) and 0.794 (10). The CuII ions exhibit slightly distorted octa­hedral geometries. In the crystal, cations and anions are connected to each other via N—H⋯O and O—H⋯O hydrogen bonds, forming a two-dimensional network parallel to (200). The inter­molecular contacts in the crystal were further analysed using Hirshfeld surface analysis, which indicates that the most significant contacts are O⋯H/H⋯O (42.9%), followed by H⋯H (35.7%), C⋯H/H⋯C (14.2%), C⋯C (2.9%), C⋯O/O⋯C (2.2%), N⋯H/H⋯N (0.9%) and N⋯O/O⋯N (0.3%).




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The 1:2 co-crystal formed between N,N'-bis(pyridin-4-ylmeth­yl)ethanedi­amide and benzoic acid: crystal structure, Hirshfeld surface analysis and computational study

The crystal and mol­ecular structures of the title 1:2 co-crystal, C14H14N4O2·2C7H6O2, are described. The oxalamide mol­ecule has a (+)-anti­periplanar conformation with the 4-pyridyl residues lying to either side of the central, almost planar C2N2O2 chromophore (r.m.s. deviation = 0.0555 Å). The benzoic acid mol­ecules have equivalent, close to planar conformations [C6/CO2 dihedral angle = 6.33 (14) and 3.43 (10)°]. The formation of hy­droxy-O—H⋯N(pyrid­yl) hydrogen bonds between the benzoic acid mol­ecules and the pyridyl residues of the di­amide leads to a three-mol­ecule aggregate. Centrosymmetrically related aggregates assemble into a six-mol­ecule aggregate via amide-N—H⋯O(amide) hydrogen bonds through a 10-membered {⋯HNC2O}2 synthon. These are linked into a supra­molecular tape via amide-N—H⋯O(carbon­yl) hydrogen bonds and 22-membered {⋯HOCO⋯NC4NH}2 synthons. The contacts between tapes to consolidate the three-dimensional architecture are of the type methyl­ene-C—H⋯O(amide) and pyridyl-C—H⋯O(carbon­yl). These inter­actions are largely electrostatic in nature. Additional non-covalent contacts are identified from an analysis of the calculated Hirshfeld surfaces.




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Hydrogen-bonding patterns in 2,2-bis­(4-methyl­phen­yl)hexa­fluoro­propane pyridinium and ethyl­enedi­ammonium salt crystals

The crystal structures of two salt crystals of 2,2-bis­(4-methyl­phen­yl)hexa­fluoro­propane (Bmphfp) with amines, namely, dipyridinium 4,4'-(1,1,1,3,3,3-hexa­fluoro­propane-2,2-di­yl)dibenzoate 4,4'-(1,1,1,3,3,3-hexa­fluoro­propane-2,2-di­yl)di­benzoic acid, 2C5H6N+·C17H8F6O42−·C17H10F6O4, (1), and a monohydrated ethyl­enedi­ammonium salt ethane-1,2-diaminium 4,4'-(1,1,1,3,3,3-hexa­fluoro­propane-2,2-di­yl)dibenzoate monohydrate, C2H10N22+·C17H8F6O42−·H2O, (2), are reported. Compounds 1 and 2 crystallize, respectively, in space group P21/c with Z' = 2 and in space group Pbca with Z' = 1. The crystals of compound 1 contain neutral and anionic Bmphfp mol­ecules, and form a one-dimensional hydrogen-bonded chain motif. The crystals of compound 2 contain anionic Bmphfp mol­ecules, which form a complex three-dimensional hydrogen-bonded network with the ethyl­enedi­amine and water mol­ecules.




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Handbook of Industrial Crystallization. Third edition. Edited by Allan S. Myerson, Deniz Erdemir and Alfred Y. Lee. Cambridge University Press, 2019. Pp. 538. Price GBP 145 (hardcover). ISBN 9780521196185.




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Formation of a highly dense tetra-rhenium cluster in a protein crystal and its implications in medical imaging

The fact that a protein crystal can serve as a chemical reaction vessel is intrinsically fascinating. That it can produce an electron-dense tetranuclear rhenium cluster compound from a rhenium tri­carbonyl tri­bromo starting compound adds to the fascination. Such a cluster has been synthesized previously in vitro, where it formed under basic conditions. Therefore, its synthesis in a protein crystal grown at pH 4.5 is even more unexpected. The X-ray crystal structures presented here are for the protein hen egg-white lysozyme incubated with a rhenium tri­carbonyl tri­bromo compound for periods of one and two years. These reveal a completed, very well resolved, tetra-rhenium cluster after two years and an intermediate state, where the carbonyl ligands to the rhenium cluster are not yet clearly resolved, after one year. A dense tetranuclear rhenium cluster, and its technetium form, offer enhanced contrast in medical imaging. Stimulated by these crystallography results, the unusual formation of such a species directly in an in vivo situation has been considered. It offers a new option for medical imaging compounds, particularly when considering the application of the pre-formed tetranuclear cluster, suggesting that it may be suitable for medical diagnosis because of its stability, preference of formation and biological compatibility.




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Structural changes during water-mediated amorphization of semiconducting two-dimensional thio­stannates

Owing to their combined open-framework structures and semiconducting properties, two-dimensional thio­stannates show great potential for catalytic and sensing applications. One such class of crystalline materials consists of porous polymeric [Sn3S72−]n sheets with molecular cations embedded in-between. The compounds are denoted R-SnS-1, where R is the cation. Dependent on the cation, some R-SnS-1 thio­stannates transition into amorphous phases upon dispersion in water. Knowledge about the fundamental chemical properties of the thio­stannates, including their water stability and the nature of the amorphous products, has not yet been established. This paper presents a time-resolved study of the transition from the crystalline to the amorphous phase of two violet-light absorbing thio­stannates, i.e. AEPz-SnS-1 [AEPz = 1-(2-amino­ethyl)­piperazine] and trenH-SnS-1 [tren = tris­(2-amino­ethyl)­amine]. X-ray total scattering data and pair distribution function analysis reveal no change in the local intralayer coordination during the amorphization. However, a rapid decrease in the crystalline domain sizes upon suspension in water is demonstrated. Although scanning electron microscopy shows no significant decrease of the micrometre-sized particles, transmission electron microscopy reveals the formation of small particles (∼200–400 nm) in addition to the larger particles. The amorphization is associated with disorder of the thio­stannate nanosheet stacking. For example, an average decrease in the interlayer distance (from 19.0 to 15.6 Å) is connected to the substantial loss of the organic components as shown by elemental analysis and X-ray photoelectron spectroscopy. Despite the structural changes, the light absorption properties of the amorphisized R-SnS-1 compounds remain intact, which is encouraging for future water-based applications of such materials.




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The predictive power of data-processing statistics

This study describes a method to estimate the likelihood of success in determining a macromolecular structure by X-ray crystallography and experimental single-wavelength anomalous dispersion (SAD) or multiple-wavelength anomalous dispersion (MAD) phasing based on initial data-processing statistics and sample crystal properties. Such a predictive tool can rapidly assess the usefulness of data and guide the collection of an optimal data set. The increase in data rates from modern macromolecular crystallography beamlines, together with a demand from users for real-time feedback, has led to pressure on computational resources and a need for smarter data handling. Statistical and machine-learning methods have been applied to construct a classifier that displays 95% accuracy for training and testing data sets compiled from 440 solved structures. Applying this classifier to new data achieved 79% accuracy. These scores already provide clear guidance as to the effective use of computing resources and offer a starting point for a personalized data-collection assistant.




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Probing the structural pathway of conformational polymorph nucleation by comparing a series of α,ω-alkanedicarboxylic acids

Herein the nucleation pathway of conformational polymorphs was revealed by studying the relationships and distinctions among a series of α,ω-alkanedicarboxylic acids [HOOC–(CH2)n−2–COOH, named DAn, where n = 5, 7, 9, 11, 13, 15] in the solid state and in solution. Their polymorphic outcomes, with the exception of DA5, show solvent dependence: form I with conformation I crystallizes from solvents with hydrogen-bond donating (HBD) ability, whereas form II with conformation II crystallizes preferentially from solvents with no HBD ability. In contrast, form II of DA5 does not crystallize in any of the solvents used. Quantum mechanical computation showed that there is no direct conformational link between the solvents and the resultant polymorphic outcomes. Surprisingly, solute aggregates were found in no-HBD solvents by Fourier transform infrared spectroscopy, and only monomers could be detected in HBD solvents, suggesting stronger solvation. Furthermore, it was found that all six compounds including DA5 followed the same pattern in solution. Moreover, crystal-packing efficiency calculations and stability tests stated that dimorphs of DA5 bear a greater stability difference than others. These suggest that the rearrangement from conformation II to I could not be limited by hard desolvation in HBD solvents, where form I was also obtained. In other systems, metastable II was produced in the same solvents, probably as a result of the rearrangement being limited by hard desolvation. In this work, a comparative study uncovers the proposed nucleation pathway: difficulty in desolvation has a remarkable effect on the result of rearrangement and nucleation outcome.




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Prediction of models for ordered solvent in macromolecular structures by a classifier based upon resolution-independent projections of local feature data

Current software tools for the automated building of models for macro­molecular X-ray crystal structures are capable of assembling high-quality models for ordered macromolecule and small-molecule scattering components with minimal or no user supervision. Many of these tools also incorporate robust functionality for modelling the ordered water molecules that are found in nearly all macromolecular crystal structures. However, no current tools focus on differentiating these ubiquitous water molecules from other frequently occurring multi-atom solvent species, such as sulfate, or the automated building of models for such species. PeakProbe has been developed specifically to address the need for such a tool. PeakProbe predicts likely solvent models for a given point (termed a `peak') in a structure based on analysis (`probing') of its local electron density and chemical environment. PeakProbe maps a total of 19 resolution-dependent features associated with electron density and two associated with the local chemical environment to a two-dimensional score space that is independent of resolution. Peaks are classified based on the relative frequencies with which four different classes of solvent (including water) are observed within a given region of this score space as determined by large-scale sampling of solvent models in the Protein Data Bank. Designed to classify peaks generated from difference density maxima, PeakProbe also incorporates functionality for identifying peaks associated with model errors or clusters of peaks likely to correspond to multi-atom solvent, and for the validation of existing solvent models using solvent-omit electron-density maps. When tasked with classifying peaks into one of four distinct solvent classes, PeakProbe achieves greater than 99% accuracy for both peaks derived directly from the atomic coordinates of existing solvent models and those based on difference density maxima. While the program is still under development, a fully functional version is publicly available. PeakProbe makes extensive use of cctbx libraries, and requires a PHENIX licence and an up-to-date phenix.python environment for execution.




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Calcium-ligand variants of the myocilin olfactomedin propeller selected from invertebrate phyla reveal cross-talk with N-terminal blade and surface helices

Olfactomedins are a family of modular proteins found in multicellular organisms that all contain five-bladed β-propeller olfactomedin (OLF) domains. In support of differential functions for the OLF propeller, the available crystal structures reveal that only some OLF domains harbor an internal calcium-binding site with ligands derived from a triad of residues. For the myocilin OLF domain (myoc-OLF), ablation of the ion-binding site (triad Asp, Asn, Asp) by altering the coordinating residues affects the stability and overall structure, in one case leading to misfolding and glaucoma. Bioinformatics analysis reveals a variety of triads with possible ion-binding characteristics lurking in OLF domains in invertebrate chordates such as Arthropoda (Asp–Glu–Ser), Nematoda (Asp–Asp–His) and Echinodermata (Asp–Glu–Lys). To test ion binding and to extend the observed connection between ion binding and distal structural rearrangements, consensus triads from these phyla were installed in the myoc-OLF. All three protein variants exhibit wild-type-like or better stability, but their calcium-binding properties differ, concomitant with new structural deviations from wild-type myoc-OLF. Taken together, the results indicate that calcium binding is not intrinsically destabilizing to myoc-OLF or required to observe a well ordered side helix, and that ion binding is a differential feature that may underlie the largely elusive biological function of OLF propellers.




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Molecular replacement using structure predictions from databases

Molecular replacement (MR) is the predominant route to solution of the phase problem in macromolecular crystallography. Where the lack of a suitable homologue precludes conventional MR, one option is to predict the target structure using bioinformatics. Such modelling, in the absence of homologous templates, is called ab initio or de novo modelling. Recently, the accuracy of such models has improved significantly as a result of the availability, in many cases, of residue-contact predictions derived from evolutionary covariance analysis. Covariance-assisted ab initio models representing structurally uncharacterized Pfam families are now available on a large scale in databases, potentially representing a valuable and easily accessible supplement to the PDB as a source of search models. Here, the unconventional MR pipeline AMPLE is employed to explore the value of structure predictions in the GREMLIN and PconsFam databases. It was tested whether these deposited predictions, processed in various ways, could solve the structures of PDB entries that were subsequently deposited. The results were encouraging: nine of 27 GREMLIN cases were solved, covering target lengths of 109–355 residues and a resolution range of 1.4–2.9 Å, and with target–model shared sequence identity as low as 20%. The cluster-and-truncate approach in AMPLE proved to be essential for most successes. For the overall lower quality structure predictions in the PconsFam database, remodelling with Rosetta within the AMPLE pipeline proved to be the best approach, generating ensemble search models from single-structure deposits. Finally, it is shown that the AMPLE-obtained search models deriving from GREMLIN deposits are of sufficiently high quality to be selected by the sequence-independent MR pipeline SIMBAD. Overall, the results help to point the way towards the optimal use of the expanding databases of ab initio structure predictions.




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Pressure-induced transformation of CH3NH3PbI3: the role of the noble-gas pressure transmitting media

The photovoltaic perovskite, methyl­ammonium lead triiodide [CH3NH3PbI3 (MAPbI3)], is one of the most efficient materials for solar energy conversion. Various kinds of chemical and physical modifications have been applied to MAPbI3 towards better understanding of the relation between composition, structure, electronic properties and energy conversion efficiency of this material. Pressure is a particularly useful tool, as it can substantially reduce the interatomic spacing in this relatively soft material and cause significant modifications to the electronic structure. Application of high pressure induces changes in the crystal symmetry up to a threshold level above which it leads to amorphization. Here, a detailed structural study of MAPbI3 at high hydro­static pressures using Ne and Ar as pressure transmitting media is reported. Single-crystal X-ray diffraction experiments with synchrotron radiation at room temperature in the 0–20 GPa pressure range show that atoms of both gaseous media, Ne and Ar, are gradually incorporated into MAPbI3, thus leading to marked structural changes of the material. Specifically, Ne stabilizes the high-pressure phase of NexMAPbI3 and prevents amorphization up to 20 GPa. After releasing the pressure, the crystal has the composition of Ne0.97MAPbI3, which remains stable under ambient conditions. In contrast, above 2.4 GPa, Ar accelerates an irreversible amorphization. The distinct impacts of Ne and Ar are attributed to differences in their chemical reactivity under pressure inside the restricted space between the PbI6 octahedra.




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XTIP – the world's first beamline dedicated to the synchrotron X-ray scanning tunneling microscopy technique

In recent years, there have been numerous efforts worldwide to develop the synchrotron X-ray scanning tunneling microscopy (SX-STM) technique. Here, the inauguration of XTIP, the world's first beamline fully dedicated to SX-STM, is reported. The XTIP beamline is located at Sector 4 of the Advanced Photon Source at Argonne National Laboratory. It features an insertion device that can provide left- or right-circular as well as horizontal- and vertical-linear polarization. XTIP delivers monochromatic soft X-rays of between 400 and 1900 eV focused into an environmental enclosure that houses the endstation instrument. This article discusses the beamline system design and its performance.




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Mercury 4.0: from visualization to analysis, design and prediction

The program Mercury, developed at the Cambridge Crystallographic Data Centre, was originally designed primarily as a crystal structure visualization tool. Over the years the fields and scientific communities of chemical crystallography and crystal engineering have developed to require more advanced structural analysis software. Mercury has evolved alongside these scientific communities and is now a powerful analysis, design and prediction platform which goes a lot further than simple structure visualization.




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The Philosophy of Science – A Companion. Edited by Anouk Baberousse, Denis Bonnay and Mikael Cozic. Oxford University Press, 2018. Pp. 768. Price GBP 64.00. ISBN-13 9780190690649.

Book review




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Handbook of Industrial Crystallization. Third edition. Edited by Allan S. Myerson, Deniz Erdemir and Alfred Y. Lee. Cambridge University Press, 2019. Pp. 538. Price GBP 145 (hardcover). ISBN 9780521196185.

Book review




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The mechanism of solvent-mediated desolvation transformation of lenvatinib mesylate from dimethyl sulfoxide solvate to form D

In this work, the mechanism of solvent-mediated desolvation transformation of lenvatinib mesylate (LM) was investigated. Two new solid forms of LM, a dimethyl sulfoxide (DMSO) solvate and an unsolvated form defined as form D, were discovered and characterized using powder X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, polarized light microscopy and Raman spectroscopy. To investigate the thermodynamic mechanism of solvent-mediated desolvation transformation (SMDT) from LM DMSO solvate to form D, solubilities of LM DMSO solvate and form D in binary solvent mixtures of DMSO and water at different water volume fractions and temperatures (293.15–323.15 K) were measured and correlated by non-random two liquids model. The solubility data were used to evaluate the thermodynamic driving force of the SMDT process from DMSO solvate to form D and the effect of the activities of water and DMSO on the transformation process. Raman spectroscopy was used to monitor in situ the solid phase compositions during the SMDT process from LM DMSO solvate to form D while the solution concentration was measured by the gravimetric method. The overall desolvation transformation experiments demonstrated that the SMDT process was controlled by the nucleation and growth of form D. Moreover, effects of operating factors on the SMDT process were studied and the results illustrated that water activity in solution was the paramount parameter in the SMDT process. Finally, a new SMDT mechanism was suggested and discussed.




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Crystal structures of two furazidin polymorphs revealed by a joint effort of crystal structure prediction and NMR crystallography

This work presents the crystal structure determination of two elusive polymorphs of furazidin, an antibacterial agent, employing a combination of crystal structure prediction (CSP) calculations and an NMR crystallography approach. Two previously uncharacterized neat crystal forms, one of which has two symmetry-independent molecules (form I), whereas the other one is a Z' = 1 polymorph (form II), crystallize in P21/c and P1 space groups, respectively, and both are built by different conformers, displaying different intermolecular interactions. It is demonstrated that the usage of either CSP or NMR crystallography alone is insufficient to successfully elucidate the above-mentioned crystal structures, especially in the case of the Z' = 2 polymorph. In addition, cases of serendipitous agreement in terms of 1H or 13C NMR data obtained for the CSP-generated crystal structures different from the ones observed in the laboratory (false-positive matches) are analyzed and described. While for the majority of analyzed crystal structures the obtained agreement with the NMR experiment is indicative of some structural features in common with the experimental structure, the mentioned serendipity observed in exceptional cases points to the necessity of caution when using an NMR crystallography approach in crystal structure determination.




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The mechanism of solvent-mediated desolvation transformation of lenvatinib mesylate from di­methyl sulfoxide solvate to form D

The solvent-mediated desolvation process of newly discovered lenvatinib DMSO solvate to form II at different water volume fractions and temperatures was investigated. It is confirmed that the activity of water is the most important factor affecting the desolvation process: the desolvation process only occurs when the activity of water is greater than the activity of DMSO, and one new mechanism of solvent-mediated desolvation process was proposed.




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At 1,500,000 mph, twin stars in the constellation Cancer win speediest orbit award

The stars move quickly because they are very close to each other, separated by only about one-fourth the distance from the Earth to the Moon. As a result, they share strong gravitational forces. They were once farther apart but have spiraled closer together over time. Billions of years from now, they will crash together and merge.

The post At 1,500,000 mph, twin stars in the constellation Cancer win speediest orbit award appeared first on Smithsonian Insider.




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New Zealand Embassy donates kiwi pair to National Zoo Breeding Science Center

Kiwis come to National Zoo. The Smithsonian’s National Zoo will be using a new kiwi pair donated by the New Zealand Embassy to establish a breeding science center. […]

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Enriching the Intracluster Medium

Galaxies are sometimes found in large clusters with many hundreds of members. Typically there is a giant elliptical galaxy near the center; most of these ellipticals are very bright emitters of radio radiation as a result of activity around supermassive black holes at their nuclei.

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Keepers are optimistic about Zoo’s new breeding pair of Asian small-clawed otters

The National Zoo has received a breeding pair of Asian small-clawed otters at Asia Trail for the first time. Mac, a three-year-old male from the Point Defiance Zoo in Tacoma, Wash., and Smidge, a five-year-old female from the Columbus Zoo in Ohio, arrived in April and are now in their exhibit.

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Fossil skull of an extinct toothed whale excavated from Panamanian sediments

A scientist from the Smithsonian Tropical Research Institute uses a pick to dislodge the fossil skull of an extinct toothed whale from sediments on the […]

The post Fossil skull of an extinct toothed whale excavated from Panamanian sediments appeared first on Smithsonian Insider.




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SERC sedge grass experiment mimics predicted global-change scenario

Ecologists at the Smithsonian Environmental Research Center measure the growth rate of sedge grass in a brackish Chesapeake Bay marsh. Fed a diet rich in […]

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Development will reduce carbon stored in forests, Smithsonian & Harvard scientists predict

When most people look at a forest, they see walking trails, deer yards, or firewood for next winter. But scientists at the Harvard Forest and […]

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Scientists catch black hole in a feeding frenzy

Supermassive black holes snack infrequently, making the recent discovery of a black hole in the act of feeding all the more exciting to astronomers.

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Coronal mass ejection from July 12 solar flare headed toward Earth; minor geomagnetic storm activity predicted

A July 12 news alert from NASA indicates a X1.4 class solar flare erupted from the center of the Sun, peaking July 12 at 12:52 P.M.

The post Coronal mass ejection from July 12 solar flare headed toward Earth; minor geomagnetic storm activity predicted appeared first on Smithsonian Insider.




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Smithsonian Conservation Biology Institute and George Mason University dedicate new academic facilities in Front Royal, Va.

The Smithsonian-Mason School of Conservation, a unique program in terms of its academic offerings and contributions to the field of conservation, celebrated the completion of its expansive new academic facilities today, Oct. 18, at the Smithsonian Conservation Biology Institute in Front Royal, Va.

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With no credit to Cupid, white-naped crane couples remain faithful for life

Chris Crowe, keeper of the National Zoo’s 15 white-naped cranes, is well acquainted with the strong attachments these graceful Asian birds form with their mates.

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Success in breeding endangered frogs!

The limosa harlequin frog (Atelopus limosus), an endangered species native to Panama, now has a new lease on life. The Panama Amphibian Rescue and Conservation […]

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The secret formula to feeding 900 babies: Scientists uncover milk composition of naked mole-rat queens

Parents normally feel the need to provide well for their kids. For humans, that number of offspring is usually in the single digits, but a […]

The post The secret formula to feeding 900 babies: Scientists uncover milk composition of naked mole-rat queens appeared first on Smithsonian Insider.




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Lost species of nightsnake rediscovered in Mexico

After eluding scientists for nearly 80 years, the Clarion nightsnake (Hypsiglena ochrorhyncha unaocularus), a nocturnal reptilian species that was initially discovered in the first half […]

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In the wild, biodiversity’s power surpasses what experiments predict

Hundreds of experiments have shown biodiversity fosters healthier, more productive ecosystems. But many experts doubted whether these experiments would hold up in the real world. […]

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