tan Aquarius Moon Traits: Understanding the Emotional Landscape By entertainment.howstuffworks.com Published On :: Sat, 09 Nov 2024 05:30:03 -0500 Explore the Aquarius Moon's traits, emotional depth, and how it influences relationships, creativity, and personal growth in astrology. Unlock its mysterious power. Full Article
tan Is Aquarius Woman Creative or Logical? Understanding Her Unique Mind By entertainment.howstuffworks.com Published On :: Sun, 10 Nov 2024 05:30:03 -0500 Is Aquarius woman unique? Discover her free-spirited personality, loyalty in friendship, innovative mindset, and how she navigates love and relationships. Full Article
tan Understanding Nottinghamshire’s groundwater microbial ecosystems - British Geological Survey By news.google.com Published On :: Thu, 24 Aug 2023 07:00:00 GMT Understanding Nottinghamshire’s groundwater microbial ecosystems British Geological Survey Full Article
tan Natural flood management: is geology more important than trees? - British Geological Survey By news.google.com Published On :: Thu, 23 Nov 2023 08:00:00 GMT Natural flood management: is geology more important than trees? British Geological Survey Full Article
tan My role as a stable isotope research assistant - British Geological Survey By news.google.com Published On :: Tue, 19 Dec 2023 08:00:00 GMT My role as a stable isotope research assistant British Geological Survey Full Article
tan BGS signs memorandum of understanding with Serviço Geológico do Brasil - British Geological Survey By news.google.com Published On :: Wed, 10 Apr 2024 07:00:00 GMT BGS signs memorandum of understanding with Serviço Geológico do Brasil British Geological Survey Full Article
tan Multi-species cryoEM calibration and workflow verification standard By journals.iucr.org Published On :: 2024-10-31 Cryogenic electron microscopy (cryoEM) is a rapidly growing structural biology modality that has been successful in revealing molecular details of biological systems. However, unlike established biophysical and analytical techniques with calibration standards, cryoEM has lacked comprehensive biological test samples. Here, a cryoEM calibration sample consisting of a mixture of compatible macromolecules is introduced that can not only be used for resolution optimization, but also provides multiple reference points for evaluating instrument performance, data quality and image-processing workflows in a single experiment. This combined test specimen provides researchers with a reference point for validating their cryoEM pipeline, benchmarking their methodologies and testing new algorithms. Full Article text
tan Mapping domain structures near a grain boundary in a lead zirconate titanate ferroelectric film using X-ray nanodiffraction By journals.iucr.org Published On :: Direct measurements have been taken of nanoscale domain structure in ferroelectric lead zirconate titanate around a grain boundary. Characterizing the evolution of this structure under an electric field is critical for predicting dielectric and piezoelectric response. Full Article text
tan Understanding secondary order parameters in perovskites with tilted octahedra By journals.iucr.org Published On :: A symmetry guide for the secondary structural degrees of freedom and related physical properties generated by tilts of BX6 octahedra in perovskites is proposed. Full Article text
tan Mapping domain structures near a grain boundary in a lead zirconate titanate ferroelectric film using X-ray nanodiffraction By journals.iucr.org Published On :: 2024-10-29 The effect of an electric field on local domain structure near a 24° tilt grain boundary in a 200 nm-thick Pb(Zr0.2Ti0.8)O3 bi-crystal ferroelectric film was probed using synchrotron nanodiffraction. The bi-crystal film was grown epitaxially on SrRuO3-coated (001) SrTiO3 24° tilt bi-crystal substrates. From the nanodiffraction data, real-space maps of the ferroelectric domain structure around the grain boundary prior to and during application of a 200 kV cm−1 electric field were reconstructed. In the vicinity of the tilt grain boundary, the distributions of densities of c-type tetragonal domains with the c axis aligned with the film normal were calculated on the basis of diffracted intensity ratios of c- and a-type domains and reference powder diffraction data. Diffracted intensity was averaged along the grain boundary, and it was shown that the density of c-type tetragonal domains dropped to ∼50% of that of the bulk of the film over a range ±150 nm from the grain boundary. This work complements previous results acquired by band excitation piezoresponse force microscopy, suggesting that reduced nonlinear piezoelectric response around grain boundaries may be related to the change in domain structure, as well as to the possibility of increased pinning of domain wall motion. The implications of the results and analysis in terms of understanding the role of grain boundaries in affecting the nonlinear piezoelectric and dielectric responses of ferroelectric materials are discussed. Full Article text
tan Understanding secondary order parameters in perovskites with tilted octahedra By journals.iucr.org Published On :: 2024-10-16 In the family of perovskite materials, the tilts of BX6 octahedra are the most common type of structural distortion. Conventionally, the formation of low-symmetry perovskite phases with tilted octahedra is analyzed by considering only primary order parameters. However, octahedral tilting also gives rise to secondary order parameters which contribute to additional atomic displacements, ordering and lattice distortions. Our study highlights the significant impact of secondary order parameters on the structural formation and emergent physical properties of perovskites. Through group-theoretical and crystallographic analyses, we have identified all secondary order parameters within Glazer-type tilt systems and clarified their physical manifestations. We explore the fundamental symmetry relationships among various structural degrees of freedom in perovskites, including tilt-induced ferroelasticity, correlations between displacements and ordering of atoms occupying different positions, and the potential for rigid unit rotations and unconventional octahedral tilts. Particular emphasis is placed on the emergence of secondary order parameters and their coupling with primary order parameters, as well as their symmetry-based hierarchy, illustrated through a modified Bärnighausen tree. We applied our theoretical insights to elucidate phase transitions in well known perovskites such as CaTiO3 and RMnO3 (where R = La and lanthanide ions), thereby demonstrating the significant influence of secondary order parameters on crystal structure formation. Our results serve as a symmetry-based guide for the design, identification and structural characterization of perovskites with tilted octahedra, and for understanding tilt-induced physical properties. Full Article text
tan Symmetries and symmetry-generated averages of elastic constants up to the sixth order of nonlinearity for all crystal classes, isotropy and transverse isotropy By journals.iucr.org Published On :: 2024-10-15 Algebraic expressions for averaging linear and nonlinear stiffness tensors from general anisotropy to different effective symmetries (11 Laue classes elastically representing all 32 crystal classes, and two non-crystalline symmetries: isotropic and cylindrical) have been derived by automatic symbolic computations of the arithmetic mean over the set of rotational transforms determining a given symmetry. This approach generalizes the Voigt average to nonlinear constants and desired approximate symmetries other than isotropic, which can be useful for a description of textured polycrystals and rocks preserving some symmetry aspects. Low-symmetry averages have been used to derive averages of higher symmetry to speed up computations. Relationships between the elastic constants of each symmetry have been deduced from their corresponding averages by resolving the rank-deficient system of linear equations. Isotropy has also been considered in terms of generalized Lamé constants. The results are published in the form of appendices in the supporting information for this article and have been deposited in the Mendeley database. Full Article text
tan High-throughput and high-resolution powder X-ray diffractometer consisting of six sets of 2D CdTe detectors with variable sample-to-detector distance and innovative automation system By journals.iucr.org Published On :: 2024-06-20 The demand for powder X-ray diffraction analysis continues to increase in a variety of scientific fields, as the excellent beam quality of high-brightness synchrotron light sources enables the acquisition of high-quality measurement data with high intensity and angular resolution. Synchrotron powder diffraction has enabled the rapid measurement of many samples and various in situ/operando experiments in nonambient sample environments. To meet the demands for even higher throughput measurements using high-energy X-rays at SPring-8, a high-throughput and high-resolution powder diffraction system has been developed. This system is combined with six sets of two-dimensional (2D) CdTe detectors for high-energy X-rays, and various automation systems, including a system for automatic switching among large sample environmental equipment, have been developed in the third experimental hutch of the insertion device beamline BL13XU at SPring-8. In this diffractometer system, high-brilliance and high-energy X-rays ranging from 16 to 72 keV are available. The powder diffraction data measured under ambient and various nonambient conditions can be analysed using Rietveld refinement and the pair distribution function. Using the 2D CdTe detectors with variable sample-to-detector distance, three types of scan modes have been established: standard, single-step and high-resolution. A major feature is the ability to measure a whole powder pattern with millisecond resolution. Equally important, this system can measure powder diffraction data with high Q exceeding 30 Å−1 within several tens of seconds. This capability is expected to contribute significantly to new research avenues using machine learning and artificial intelligence by utilizing the large amount of data obtained from high-throughput measurements. Full Article text
tan Nonlinear optimization for a low-emittance storage ring By journals.iucr.org Published On :: 2024-06-25 A multi-objective genetic algorithm (MOGA) is a powerful global optimization tool, but its results are considerably affected by the crossover parameter ηc. Finding an appropriate ηc demands too much computing time because MOGA needs be run several times in order to find a good ηc. In this paper, a self-adaptive crossover parameter is introduced in a strategy to adopt a new ηc for every generation while running MOGA. This new scheme has also been adopted for a multi-generation Gaussian process optimization (MGGPO) when producing trial solutions. Compared with the existing MGGPO and MOGA, the MGGPO and MOGA with the new strategy show better performance in nonlinear optimization for the design of low-emittance storage rings. Full Article text
tan {N-[1-(2-Oxidophenyl)ethylidene]-dl-alaninato}(pentane-1,5-diyl)silicon(IV) By journals.iucr.org Published On :: 2024-03-19 The title SiIV complex, C16H21NO3Si, is built up by a tridentate dinegative Schiff base ligand bound to a silacyclohexane unit. The coordination geometry of the pentacoordinated SiIV atom is a distorted trigonal bipyramid. The presence of the silacyclohexane ring in the complex leads to an unusual coordination geometry of the SiIV atom with the N atom from the Schiff base ligand and an alkyl-C atom in apical positions of the trigonal bipyramid. There is a disorder of the methyl group at the imine bond with two orientations resolved for the H atoms [major orientation = 0.55 (3)]. In the crystal, C—H⋯O interactions are found within corrugated layers of molecules parallel to the ab plane. Full Article text
tan (SC,RS)-Bromido(N-{4-methyl-1-[(4-methylphenyl)sulfanyl]pentan-2-yl}-N'-(pyridin-2-yl)imidazol-2-ylidene)palladium(II) bromide By journals.iucr.org Published On :: 2024-04-26 The molecule of the title NCNHCS pincer N-heterocyclic carbene palladium(II) complex, [PdBr(C21H25N3S)]Br, exhibits a slightly distorted square-planar coordination at the palladium(II) atom, with the five-membered chelate ring nearly planar. The six-membered chelate ring adopts an envelope conformation. Upon chelation, the sulfur atom becomes a stereogenic centre with an RS configuration induced by the chiral carbon of the precursor imidazolium salt. There are intramolecular C—H⋯Br—Pd hydrogen bonds in the structure. The two interstitial Br atoms, as the counter-anion of the structure, are both located on crystallographic twofold axes and are connected to the complex cations via C—H⋯·Br hydrogen bonds. Full Article text
tan 2-Oxo-2H-chromen-4-yl 3,3-dimethylbutanoate By journals.iucr.org Published On :: 2024-05-31 In the crystal of the title compound, C15H16O4, the molecules are connected through C—H⋯O hydrogen bonds, generating [100] chains, which are crosslinked by weak π–π stacking interactions. Full Article text
tan Diisobutylammonium triphenyl(2-thiolatoacetato-κ2O,S)stannate(IV) By journals.iucr.org Published On :: 2024-08-09 Crystals of the title salt, (C8H20N)[Sn(C6H5)3(C2H2O2S)], comprise diisobutylammonium cations and mercaptoacetatotriphenylstannate(IV) anions. The bidentate binding mode of the mercaptoacetate ligand gives rise to a five-coordinated, ionic triphenyltin complex with a distorted cis-trigonal–bipyramidal geometry around the tin atom. In the crystal, charge-assisted ammonium-N—H⋯O(carboxylate) hydrogen-bonding connects two cations and two anions into a four-ion aggregate. Two positions were resolved for one of the phenyl rings with the major component having a site occupancy factor of 0.60 (3). Full Article text
tan Bis(2-carboxyquinolinium) hexachloridostannate(IV) dihydrate By journals.iucr.org Published On :: 2024-08-30 In the hydrated title salt, (C10H8NO2)2[SnCl6]·2H2O, the tin(IV) atom is located about a center of inversion. In the crystal structure, the organic cation, the octahedral inorganic anion and the water molecule of crystallization interact through O—H⋯O, N—H⋯O and O—H⋯Cl hydrogen bonds, supplemented by weak π–π stacking between neighboring cations, and C—Cl⋯π interactions. Full Article text
tan Poly[tris(2-aminobutan-1-ol)copper(II) [hexakis-μ2-cyanido-κ12C:N-tetracopper(I)] bis(2-aminobutan-1-olato)aquacopper(II) monohydrate] By journals.iucr.org Published On :: 2024-08-30 The title structure, {[Cu(C4H11NO)3][Cu4(CN)6]·[Cu(C4H10NO)2(H2O)]·H2O}n, is made up of diperiodic honeycomb CuICN networks built from [Cu4(CN)6]2− units, together with two independent CuII complexes: six-coordinate [Cu(CH3CH2CH(NH2)CH2OH)3]2+ cations, and five-coordinate [Cu(CH3CH2CH(NH2)CH2O)2·H2O] neutral species. The two CuII complexes are not covalently bonded to the CuICN networks. Strong O—H⋯O hydrogen bonds link the CuII complexes into pairs and the pairs are hydrogen bonded into chains along the crystallographic b axis via the hydrate water molecule. In addition, O—H⋯(CN) and N—H⋯(CN) hydrogen bonds link the cations to the CuCN network. In the honeycomb polymeric moiety, all bridging cyanido ligands are disordered over two orientations, head-to-tail and tail-to-head, with occupancies for C and N atoms varying for each CN group. Full Article text
tan Concerning the structures of Lewis base adducts of titanium(IV) hexafluoroisopropoxide By journals.iucr.org Published On :: 2024-08-13 The reaction of titanium(IV) chloride with sodium hexafluoroisopropoxide, carried out in hexafluoroisopropanol, produces titanium(IV) hexafluoroisopropoxide, which is a liquid at room temperature. Recrystallization from coordinating solvents, such as acetonitrile or tetrahydrofuran, results in the formation of bis-solvate complexes. These compounds are of interest as possible Ziegler–Natta polymerization catalysts. The acetonitrile complex had been structurally characterized previously and adopts a distorted octahedral structure in which the nitrile ligands adopt a cis configuration, with nitrogen lone pairs coordinated to the metal. The low-melting tetrahydrofuran complex has not provided crystals suitable for single-crystal X-ray analysis. However, the structure of chloridotris(hexafluoroisopropoxido-κO)bis(tetrahydrofuran-κO)titanium(IV), [Ti(C3HF6O)3Cl(C4H8O)2], has been obtained and adopts a distorted octahedral coordination geometry, with a facial arrangement of the alkoxide ligands and adjacent tetrahydrofuran ligands, coordinated by way of metal–oxygen polar coordinate interactions. Full Article text
tan Occupational modulation in the (3+1)-dimensional incommensurate structure of (2S,3S)-2-amino-3-hydroxy-3-methyl-4-phenoxybutanoic acid dihydrate By journals.iucr.org Published On :: 2024-08-08 The incommensurately modulated structure of (2S,3S)-2-amino-3-hydroxy-3-methyl-4-phenoxybutanoic acid dihydrate (C11H15NO4·2H2O or I·2H2O) is described in the (3+1)-dimensional superspace group P212121(0β0)000 (β = 0.357). The loss of the three-dimensional periodicity is ascribed to the occupational modulation of one positionally disordered solvent water molecule, where the two positions are related by a small translation [ca 0.666 (9) Å] and ∼168 (5)° rotation about one of its O—H bonds, with an average 0.624 (3):0.376 (3) occupancy ratio. The occupational modulation of this molecule arises due to the competition between the different hydrogen-bonding motifs associated with each position. The structure can be very well refined in the average approximation (all satellite reflections disregarded) in the space group P212121, with the water molecule refined as disordered over two positions in a 0.625 (16):0.375 (16) ratio. The refinement in the commensurate threefold supercell approximation in the space group P1121 is also of high quality, with the six corresponding water molecules exhibiting three different occupancy ratios averaging 0.635:0.365. Full Article text
tan Salt forms of amides: protonation of acetanilide By journals.iucr.org Published On :: 2024-08-06 Treating the amide acetanilide (N-phenylacetamide, C8H9NO) with aqueous strong acids allowed the structures of five hemi-protonated salt forms of acetanilide to be elucidated. N-(1-Hydroxyethylidene)anilinium chloride–N-phenylacetamide (1/1), [(C8H9NO)2H][Cl], and the bromide, [(C8H9NO)2H][Br], triiodide, [(C8H9NO)2H][I3], tetrafluoroborate, [(C8H9NO)2H][BF4], and diiodobromide hemi(diiodine), [(C8H9NO)2H][I2Br]·0.5I2, analogues all feature centrosymmetric dimeric units linked by O—H⋯O hydrogen bonds that extend into one-dimensional hydrogen-bonded chains through N—H⋯X interactions, where X is the halide atom of the anion. Protonation occurs at the amide O atom and results in systematic lengthening of the C=O bond and a corresponding shortening of the C—N bond. The size of these geometric changes is similar to those found for hemi-protonated paracetamol structures, but less than those in fully protonated paracetamol structures. The bond angles of the amide fragments are also found to change on protonation, but these angular changes are also influenced by conformation, namely, whether the amide group is coplanar with the phenyl ring or twisted out of plane. Full Article text
tan On the importance of crystal structures for organic thin film transistors By journals.iucr.org Published On :: 2024-09-04 Historically, knowledge of the molecular packing within the crystal structures of organic semiconductors has been instrumental in understanding their solid-state electronic properties. Nowadays, crystal structures are thus becoming increasingly important for enabling engineering properties, understanding polymorphism in bulk and in thin films, exploring dynamics and elucidating phase-transition mechanisms. This review article introduces the most salient and recent results of the field. Full Article text
tan Using cryo-EM to understand the assembly pathway of respiratory complex I By journals.iucr.org Published On :: 2024-02-19 Complex I (proton-pumping NADH:ubiquinone oxidoreductase) is the first component of the mitochondrial respiratory chain. In recent years, high-resolution cryo-EM studies of complex I from various species have greatly enhanced the understanding of the structure and function of this important membrane-protein complex. Less well studied is the structural basis of complex I biogenesis. The assembly of this complex of more than 40 subunits, encoded by nuclear or mitochondrial DNA, is an intricate process that requires at least 20 different assembly factors in humans. These are proteins that are transiently associated with building blocks of the complex and are involved in the assembly process, but are not part of mature complex I. Although the assembly pathways have been studied extensively, there is limited information on the structure and molecular function of the assembly factors. Here, the insights that have been gained into the assembly process using cryo-EM are reviewed. Full Article text
tan A database overview of metal-coordination distances in metalloproteins By journals.iucr.org Published On :: 2024-04-29 Metalloproteins are ubiquitous in all living organisms and take part in a very wide range of biological processes. For this reason, their experimental characterization is crucial to obtain improved knowledge of their structure and biological functions. The three-dimensional structure represents highly relevant information since it provides insight into the interaction between the metal ion(s) and the protein fold. Such interactions determine the chemical reactivity of the bound metal. The available PDB structures can contain errors due to experimental factors such as poor resolution and radiation damage. A lack of use of distance restraints during the refinement and validation process also impacts the structure quality. Here, the aim was to obtain a thorough overview of the distribution of the distances between metal ions and their donor atoms through the statistical analysis of a data set based on more than 115 000 metal-binding sites in proteins. This analysis not only produced reference data that can be used by experimentalists to support the structure-determination process, for example as refinement restraints, but also resulted in an improved insight into how protein coordination occurs for different metals and the nature of their binding interactions. In particular, the features of carboxylate coordination were inspected, which is the only type of interaction that is commonly present for nearly all metals. Full Article text
tan A small step towards an important goal: fragment screen of the c-di-AMP-synthesizing enzyme CdaA By journals.iucr.org Published On :: 2024-04-29 CdaA is the most widespread diadenylate cyclase in many bacterial species, including several multidrug-resistant human pathogens. The enzymatic product of CdaA, cyclic di-AMP, is a secondary messenger that is essential for the viability of many bacteria. Its absence in humans makes CdaA a very promising and attractive target for the development of new antibiotics. Here, the structural results are presented of a crystallographic fragment screen against CdaA from Listeria monocytogenes, a saprophytic Gram-positive bacterium and an opportunistic food-borne pathogen that can cause listeriosis in humans and animals. Two of the eight fragment molecules reported here were localized in the highly conserved ATP-binding site. These fragments could serve as potential starting points for the development of antibiotics against several CdaA-dependent bacterial species. Full Article text
tan Crystal structure of vancomycin bound to the resistance determinant d-alanine-d-serine By journals.iucr.org Published On :: 2024-01-26 Vancomycin is a glycopeptide antibiotic that for decades has been a mainstay of treatment for persistent bacterial infections. However, the spread of antibiotic resistance threatens its continued utility. In particular, vancomycin-resistant enterococci (VRE) have become a pressing clinical challenge. Vancomycin acts by binding and sequestering the intermediate Lipid II in cell-wall biosynthesis, specifically recognizing a d-alanine-d-alanine dipeptide motif within the Lipid II molecule. VRE achieve resistance by remodeling this motif to either d-alanine-d-lactate or d-alanine-d-serine; the former substitution essentially abolishes recognition by vancomycin of Lipid II, whereas the latter reduces the affinity of the antibiotic by roughly one order of magnitude. The complex of vancomycin bound to d-alanine-d-serine has been crystallized, and its 1.20 Å X-ray crystal structure is presented here. This structure reveals that the d-alanine-d-serine ligand is bound in essentially the same position and same pose as the native d-alanine-d-alanine ligand. The serine-containing ligand appears to be slightly too large to be comfortably accommodated in this way, suggesting one possible contribution to the reduced binding affinity. In addition, two flexible hydroxyl groups – one from the serine side chain of the ligand, and the other from a glucose sugar on the antibiotic – are locked into single conformations in the complex, which is likely to contribute an unfavorable entropic component to the recognition of the serine-containing ligand. Full Article text
tan Cocrystals of a coumarin derivative: an efficient approach towards anti-leishmanial cocrystals against MIL-resistant Leishmania tropica By journals.iucr.org Published On :: 2024-03-01 Leishmaniasis is a neglected parasitic tropical disease with numerous clinical manifestations. One of the causative agents of cutaneous leishmaniasis (CL) is Leishmania tropica (L. tropica) known for causing ulcerative lesions on the skin. The adverse effects of the recommended available drugs, such as amphotericin B and pentavalent antimonial, and the emergence of drug resistance in parasites, mean the search for new safe and effective anti-leishmanial agents is crucial. Miltefosine (MIL) was the first recommended oral medication, but its use is now limited because of the rapid emergence of resistance. Pharmaceutical cocrystallization is an effective method to improve the physicochemical and biological properties of active pharmaceutical ingredients (APIs). Herein, we describe the cocrystallization of coumarin-3-carboxylic acid (CU, 1a; 2-oxobenzopyrane-3-carboxylic acid, C10H6O4) with five coformers [2-amino-3-bromopyridine (1b), 2-amino-5-(trifluoromethyl)-pyridine (1c), 2-amino-6-methylpyridine (1d), p-aminobenzoic acid (1e) and amitrole (1f)] in a 1:1 stoichiometric ratio via the neat grinding method. The cocrystals 2–6 obtained were characterized via single-crystal X-ray diffraction, powder X-ray diffraction, differential scanning calorimetry and thermogravimetric analysis, as well as Fourier transform infrared spectroscopy. Non-covalent interactions, such as van der Waals, hydrogen bonding, C—H⋯π and π⋯π interactions contribute significantly towards the packing of a crystal structure and alter the physicochemical and biological activity of CU. In this research, newly synthesized cocrystals were evaluated for their anti-leishmanial activity against the MIL-resistant L. tropica and cytotoxicity against the 3T3 (normal fibroblast) cell line. Among the non-cytotoxic cocrystals synthesized (2–6), CU:1b (2, IC50 = 61.83 ± 0.59 µM), CU:1c (3, 125.7 ± 1.15 µM) and CU:1d (4, 48.71 ± 0.75 µM) appeared to be potent anti-leishmanial agents and showed several-fold more anti-leishmanial potential than the tested standard drug (MIL, IC50 = 169.55 ± 0.078 µM). The results indicate that cocrystals 2–4 are promising anti-leishmanial agents which require further exploration. Full Article text
tan The importance of definitions in crystallography By journals.iucr.org Published On :: 2024-05-28 This paper was motivated by the articles `Same or different – that is the question' in CrystEngComm (July 2020) and `Change to the definition of a crystal' in the IUCr Newsletter (June 2021). Experimental approaches to crystal comparisons require rigorously defined classifications in crystallography and beyond. Since crystal structures are determined in a rigid form, their strongest equivalence in practice is rigid motion, which is a composition of translations and rotations in 3D space. Conventional representations based on reduced cells and standardizations theoretically distinguish all periodic crystals. However, all cell-based representations are inherently discontinuous under almost any atomic displacement that can arbitrarily scale up a reduced cell. Hence, comparison of millions of known structures in materials databases requires continuous distance metrics. Full Article text
tan The evolution of raw data archiving and the growth of its importance in crystallography By journals.iucr.org Published On :: 2024-06-12 The hardware for data archiving has expanded capacities for digital storage enormously in the past decade or more. The IUCr evaluated the costs and benefits of this within an official working group which advised that raw data archiving would allow ground truth reproducibility in published studies. Consultations of the IUCr's Commissions ensued via a newly constituted standing advisory committee, the Committee on Data. At all stages, the IUCr financed workshops to facilitate community discussions and possible methods of raw data archiving implementation. The recent launch of the IUCrData journal's Raw Data Letters is a milestone in the implementation of raw data archiving beyond the currently published studies: it includes diffraction patterns that have not been fully interpreted, if at all. The IUCr 75th Congress in Melbourne included a workshop on raw data reuse, discussing the successes and ongoing challenges of raw data reuse. This article charts the efforts of the IUCr to facilitate discussions and plans relating to raw data archiving and reuse within the various communities of crystallography, diffraction and scattering. Full Article text
tan Importance of powder diffraction raw data archival in a curated database for materials science applications By journals.iucr.org Published On :: 2024-08-26 In recent years, there is a significant interest from the crystallographic and materials science communities to have access to raw diffraction data. The effort in archiving raw data for access by the user community is spearheaded by the International Union of Crystallography (IUCr) Committee on Data. In materials science, where powder diffraction is extensively used, the challenge in archiving raw data is different to that from single crystal data, owing to the very nature of the contributions involved. Powder diffraction (X-ray or neutron) data consist of contributions from the material under study as well as instrument specific parameters. Having raw powder diffraction data can be essential in cases of analysing materials with poor crystallinity, disorder, micro structure (size/strain) etc. Here, the initiative and progress made by the International Centre for Diffraction Data (ICDDR) in archiving powder X-ray diffraction raw data in the Powder Diffraction FileTM (PDFR) database is outlined. The upcoming 2025 release of the PDF-5+ database will have more than 20 800 raw powder diffraction patterns that are available for reference. Full Article text
tan Crystal structure and Hirshfeld surface analysis of (2Z)-3-oxo-N-phenyl-2-[(1H-pyrrol-2-yl)methylidene]butanamide monohydrate By journals.iucr.org Published On :: 2023-11-14 In the title compound, C15H14N2O2·H2O, the 1H-pyrrole ring makes a dihedral angle of 59.95 (13)° with the phenyl ring. In the crystal, the molecules are connected by C—H⋯O hydrogen bonds into layers parallel to the (020) plane, while two molecules are connected to the water molecule by two N—H⋯O hydrogen bonds and one molecule by an O—H⋯O hydrogen bond. C—H⋯π and π–π interactions further link the molecules into chains extending in the [overline{1}01] direction and stabilize the molecular packing. According to a Hirshfeld surface study, H⋯H (49.4%), C⋯H/H⋯C (23.2%) and O⋯H/H⋯O (20.0%) interactions are the most significant contributors to the crystal packing. Full Article text
tan Synthesis and crystal structures of bis[1-oxopyridin-2-olato(1−)]bis(pentafluorophenyl)silicon(IV)–tetrahydrofuran–pentane (2/1/1), bis[1-oxopyridin-2-olato(1−)]bis(p-tolyl)silicon(IV), and dimes By journals.iucr.org Published On :: 2024-02-20 The neutral organosilicon(IV) complex, (C6F5)2Si(OPO)2 (OPO = 1-oxopyridin-2-one, C5H4NO2), was synthesized from (C6F5)2Si(OCH3)2 and 2 equiv. of 1-hydroxypyridin-2-one in tetrahydrofuran (THF). Single crystals grown from the diffusion of n-pentane into a THF solution were identified as a THF hemisolvate and an n-pentane hemisolvate, (C6F5)2Si(OPO)2·0.5THF·0.5C5H12 (1). p-Tolyl2Si(OPO)2 (2) and mesityl2Si(OPO)2 (3) crystallized directly from reaction mixtures of 2 equiv. of Me3Si(OPO) with p-tolyl2SiCl2 and mesityl2SiCl2, respectively, in acetonitrile. The oxygen-bonded carbon and nitrogen atoms of the OPO ligands in 1, 2, and 3 were modeled as disordered indicating co-crystallization of up to three possible diastereomers in each. Solution NMR studies support the presence of exclusively the all-cis isomer in 1 and multiple isomers in 2. Poor solubility of 3 limited its characterization in solution. Full Article text
tan Structural characterization of the supramolecular complex between a tetraquinoxaline-based cavitand and benzonitrile By journals.iucr.org Published On :: 2024-05-31 The structural characterization is reported of the supramolecular complex between the tetraquinoxaline-based cavitand 2,8,14,20-tetrahexyl-6,10:12,16:18,22:24,4-O,O'-tetrakis(quinoxaline-2,3-diyl)calix[4]resorcinarene (QxCav) with benzonitrile. The complex, of general formula C84H80N8O8·2C7H5N, crystallizes in the space group Poverline{1} with two independent molecules in the asymmetric unit, displaying very similar geometrical parameters. For each complex, one of the benzonitrile molecules is engulfed inside the cavity, while the other is located among the alkyl legs at the lower rim. The host and the guests mainly interact through weak C—H⋯π, C—H⋯N and dispersion interactions. These interactions help to consolidate the formation of supramolecular chains running along the crystallographic b-axis direction. Full Article text
tan Crystal structure of (1,4,7,10,13,16-hexaoxacyclooctadecane-κ6O)potassium-μ-oxalato-triphenylstannate(IV), the first reported 18-crown-6-stabilized potassium salt of triphenyloxalatostannate By journals.iucr.org Published On :: 2024-08-13 The title complex, (1,4,7,10,13,16-hexaoxacyclooctadecane-1κ6O)(μ-oxalato-1κ2O1,O2:2κ2O1',O2')triphenyl-2κ3C-potassium(I)tin(IV), [KSn(C6H5)3(C2O4)(C12H24O6)] or K[18-Crown-6][(C6H5)3SnO4C2], was synthesized. The complex consists of a potassium cation coordinated to the six oxygen atoms of a crown ether molecule and the two oxygen atoms of the oxalatotriphenylstannate anion. It crystallizes in the monoclinic crystal system within the space group P21. The tin atom is coordinated by one chelating oxalate ligand and three phenyl groups, forming a cis-trigonal–bipyramidal geometry around the tin atom. The cations and anions form ion pairs, linked through carbonyl coordination to the potassium atoms. The crystal structure features C—H⋯O hydrogen bonds between the oxygen atoms of the oxalate group and the hydrogen atoms of the phenyl groups, resulting in an infinite chain structure extending along a-axis direction. The primary inter-chain interactions are van der Waals forces. Full Article text
tan X-ray standing wave characterization of the strong metal–support interaction in Co/TiOx model catalysts By journals.iucr.org Published On :: 2024-03-31 The strong metal–support interaction (SMSI) is a phenomenon observed in supported metal catalyst systems in which reducible metal oxide supports can form overlayers over the surface of active metal nanoparticles (NPs) under a hydrogen (H2) environment at elevated temperatures. SMSI has been shown to affect catalyst performance in many reactions by changing the type and number of active sites on the catalyst surface. Laboratory methods for the analysis of SMSI at the nanoparticle-ensemble level are lacking and mostly based on indirect evidence, such as gas chemisorption. Here, we demonstrate the possibility to detect and characterize SMSIs in Co/TiOx model catalysts using the laboratory X-ray standing wave (XSW) technique for a large ensemble of NPs at the bulk scale. We designed a thermally stable MoNx/SiNx periodic multilayer to retain XSW generation after reduction with H2 gas at 600°C. The model catalyst system was synthesized here by deposition of a thin TiOx layer on top of the periodic multilayer, followed by Co NP deposition via spare ablation. A partial encapsulation of Co NPs by TiOx was identified by analyzing the change in Ti atomic distribution. This novel methodological approach can be extended to observe surface restructuring of model catalysts in situ at high temperature (up to 1000°C) and pressure (≤3 mbar), and can also be relevant for fundamental studies in the thermal stability of membranes, as well as metallurgy. Full Article text
tan Laboratory-based 3D X-ray standing-wave analysis of nanometre-scale gratings By journals.iucr.org Published On :: 2024-08-19 The increasing structural complexity and downscaling of modern nanodevices require continuous development of structural characterization techniques that support R&D and manufacturing processes. This work explores the capability of laboratory characterization of periodic planar nanostructures using 3D X-ray standing waves as a promising method for reconstructing atomic profiles of planar nanostructures. The non-destructive nature of this metrology technique makes it highly versatile and particularly suitable for studying various types of samples. Moreover, it eliminates the need for additional sample preparation before use and can achieve sub-nanometre reconstruction resolution using widely available laboratory setups, as demonstrated on a diffractometer equipped with a microfocus X-ray tube with a copper anode. Full Article text
tan Coordinate-based simulation of pair distance distribution functions for small and large molecular assemblies: implementation and applications By journals.iucr.org Published On :: 2024-09-17 X-ray scattering has become a major tool in the structural characterization of nanoscale materials. Thanks to the widely available experimental and computational atomic models, coordinate-based X-ray scattering simulation has played a crucial role in data interpretation in the past two decades. However, simulation of real-space pair distance distribution functions (PDDFs) from small- and wide-angle X-ray scattering, SAXS/WAXS, has been relatively less exploited. This study presents a comparison of PDDF simulation methods, which are applied to molecular structures that range in size from β-cyclodextrin [1 kDa molecular weight (MW), 66 non-hydrogen atoms] to the satellite tobacco mosaic virus capsid (1.1 MDa MW, 81 960 non-hydrogen atoms). The results demonstrate the power of interpretation of experimental SAXS/WAXS from the real-space view, particularly by providing a more intuitive method for understanding of partial structure contributions. Furthermore, the computational efficiency of PDDF simulation algorithms makes them attractive as approaches for the analysis of large nanoscale materials and biological assemblies. The simulation methods demonstrated in this article have been implemented in stand-alone software, SolX 3.0, which is available to download from https://12idb.xray.aps.anl.gov/solx.html. Full Article text
tan Foreword to the special virtual issue on X-ray spectroscopy to understand functional materials: instrumentation, applications, data analysis By journals.iucr.org Published On :: 2024-10-21 Full Article text
tan Careem Pay introduces instant transfers for customers in Europe By thepaypers.com Published On :: Tue, 12 Nov 2024 14:22:00 +0100 Digital wallet and fintech platform Careem Pay has launched... Full Article
tan Genome introduces SEPA Instant Transfers for Eurozone payments By thepaypers.com Published On :: Tue, 22 Oct 2024 10:48:00 +0100 Lithuania-based Genome has launched SEPA Instant Transfers,... Full Article
tan Africhange secures IMTO licence to streamline remittance to Nigeria By thepaypers.com Published On :: Fri, 08 Nov 2024 14:45:00 +0100 Africhange has announced that its Nigerian branch, Currenzo,... Full Article
tan Why Liam Neeson was 'very reluctant' to star in 'A Walk Among the Tombstones' By www.scpr.org Published On :: Fri, 19 Sep 2014 18:17:46 -0700 Liam Neeson stars as Matthew Scudder in "A Walk Among the Tombstones." ; Credit: Universal Pictures Screenwriter and director Scott Frank has been trying to make “A Walk Among the Tombstones” for more than a decade, but it wasn't until Liam Neeson signed on that his efforts finally came into view. Based on the Lawrence Block novel, “Tombstones” stars Liam Neeson as Matthew Scudder, an ex-cop working as an unlicensed private investigator. He agrees to help a well-to-do drug trafficker hunt down the kidnappers who have brutally murdered his wife. Frank wrote the screenplay and, after the departures of other attached directors, Frank decided to step behind the cameras himself. When he came by The Frame studio, Frank spoke with host John Horn about Neeson's great strengths as an action hero and how he convinced Neeson to sign on to the project. Interview Highlights: John Horn: Liam Neeson has evolved in a fascinating way as an action hero. When did you start having conversations with him about this movie, and what was it about him as an actor that made it feel like the right fit? "Well, what's interesting is that Larry Block, the novelist, had always said, going way back to 2003 or something, that the perfect actor for this, after [he saw] 'Michael Collins'...would be Liam Neeson. Chris Andrews, who is Liam's agent, always loved the script and was always trying to find a way to put it together, and he's the one who gave it to Liam back when D.J. [Caruso] was going to direct. So the first time I met Liam to talk about the movie, I was talking to him as the writer, not as the director of the movie. And then when D.J. fell out to go do a different movie at Sony...we had a conversation about directing the movie. JH: Was this before or after the first "Taken" had come out? This was well after the first 'Taken,' this was right before the second 'Taken.' JH: So Liam is...succeeding as a version of that character, and I wonder if that success cuts both ways, that maybe there's a reluctance on his part to not do something that's quite as similar? Or is that part of your conversation that you have with him? It absolutely cuts both ways, and that was a huge part of the conversation because there's a kidnapping in this story, and there he is on the telephone for a few minutes at the end of the movie talking to kidnappers, and there are similarities [to 'Taken']. And he knew that was the way to sell the movie, and so he was very reluctant. And I talked to him and I had him watch 'Klute,' and I said, "That's the movie we're gonna make. We're not going to make 'Taken,' we're going to make a movie that's like 'Klute,' or a little bit like 'Dirty Harry,' or one of those old-school '70s films. It's going to feel more like that than an action movie." JH: Liam Neeson's not physically imposing, but there's something about him that really kind of makes the hair on the back of your neck stand up. What is it about him as an actor in this kind of part? Well, there's a couple things. One: you believe him. No matter what he's talking about, it seems authentic and true...he has this thing about him that, whatever he's doing, you believe him. Two: he's one of those actors like Gene Hackman where he can convey exposition and make it feel like character. He can talk pages of exposition and make it all feel like it's character and drama — it's a great thing. The other thing about him is that he has this real gravitas, and it almost borders on sadness sometimes; it's interesting when you watch him and you feel like there's all this other life going on behind him. JH: That he has nothing to lose, in other words. Nothing to lose, and he says that at one point in the film, but I think it's those things that are all at work at the same time. Full Article
tan Boxo and Nium launch white-label remittance platform for apps By thepaypers.com Published On :: Fri, 08 Nov 2024 08:18:00 +0100 Boxo has partnered with global payments infrastructure firm Full Article
tan Félix Pago partners with Mastercard to expand digital remittances By thepaypers.com Published On :: Tue, 12 Nov 2024 15:10:00 +0100 US-based fintech Felix Pago has announced a partnership... Full Article
tan Mbank partners with AEP for Aani Instant Payments launch By thepaypers.com Published On :: Wed, 13 Nov 2024 12:30:00 +0100 Mbank has partnered with Al Etihad Payments Company (AEP), a Central Bank of the UAE (CBUAE) subsidiary, to introduce the Aani Instant Payment Platform on its mobile application. Full Article
tan The Pandemic Led To The Biggest Drop In U.S. Life Expectancy Since WWII, Study Finds By www.scpr.org Published On :: Wed, 23 Jun 2021 17:40:11 -0700 A COVID-19 vaccination clinic last month in Auburn, Maine. A drop in life expectancy in the U.S. stems largely from the coronavirus pandemic, a new study says.; Credit: Robert F. Bukaty/AP Allison Aubrey | NPRA new study estimates that life expectancy in the U.S. decreased by nearly two years between 2018 and 2020, largely due to the COVID-19 pandemic. And the declines were most pronounced among minority groups, including Black and Hispanic people. In 2018, average life expectancy in the U.S. was about 79 years (78.7). It declined to about 77 years (76.9) by the end of 2020, according to a new study published in the British Medical Journal. "We have not seen a decrease like this since World War II. It's a horrific decrease in life expectancy," said Steven Woolf of the Virginia Commonwealth University School of Medicine and an author of the study released on Wednesday. (The study is based on data from the National Center for Health Statistics and includes simulated estimates for 2020.) Beyond the more than 600,000 deaths in the U.S. directly from the coronavirus, other factors play into the decreased longevity, including "disruptions in health care, disruptions in chronic disease management, and behavioral health crisis, where people struggling with addiction disorders or depression might not have gotten the help that they needed," Woolf said. The lack of access to care and other pandemic-related disruptions hit some Americans much harder than others. And it's been well documented that the death rate for Black Americans was twice as high compared with white Americans. The disparity is reflected in the new longevity estimates. "African Americans saw their life expectancy decrease by 3.3 years and Hispanic Americans saw their life expectancy decrease by 3.9 years," Woolf noted. "These are massive numbers," Woolf said, that reflect the systemic inequalities that long predate the pandemic. "It is impossible to look at these findings and not see a reflection of the systemic racism in the U.S.," Lesley Curtis, chair of the Department of Population Health Sciences at Duke University School of Medicine, told NPR. "This study further destroys the myth that the United States is the healthiest place in the world to live," Dr. Richard Besser, president of the Robert Wood Johnson Foundation (an NPR funder), said in an email. He said wide differences in life expectancy rates were evident before COVID-19. "For example, life expectancy in Princeton, NJ—a predominantly White community—is 14 years higher than Trenton, NJ, a predominantly Black and Latino city only 14 miles away," Besser said. Life expectancy in the U.S. had already been declining — albeit slowly — in the years leading up to the pandemic. And the U.S. has been losing ground compared with other wealthy countries, said Magali Barbieri of the University of California, Berkeley, in an editorial published alongside the new study. The study estimates that the decline in life expectancy was .22 years (or about one-fifth of a year) in a group of 16 peer countries (including Austria, Finland, France, Israel, the Netherlands and the United Kingdom) compared with the nearly two-year decline in the United States. "The U.S. disadvantage in mortality compared with other high income democracies in 2020 is neither new nor sudden," Barbieri wrote. It appears the pandemic has magnified existing vulnerabilities in U.S. society, she added. "The range of factors that play into this include income inequality, the social safety net, as well as racial inequality and access to health care," Duke's Curtis said. So, what's the prognosis going forward in the United States? "I think life expectancy will rebound," Woolf of Virginia Commonwealth said. But it's unlikely that the U.S. is on course to reverse the trend entirely. "The U.S. has some of the best hospitals and some of the greatest scientists. But other countries do far better in getting quality medical care to their population," Woolf said. "We have big gaps in getting care to people who need it most, when they need it most." Copyright 2021 NPR. To see more, visit https://www.npr.org. This content is from Southern California Public Radio. View the original story at SCPR.org. Full Article
tan High-Grade Rhodium Intercepts Bolster Montana Critical Minerals Expansion By www.streetwisereports.com Published On :: Mon, 04 Nov 2024 00:00:00 PST Stillwater Critical Minerals Corp. (PGE:TSX.V; PGEZF:OTCQB; J0G:FSE) has announced new assay results from its ongoing resource expansion drilling at the Stillwater West PGE-Ni-Cu-Co + Au project. Read more for detailed insights into the high-grade rhodium intercepts and resource expansion potential. Full Article PGE:TSX.V; PGEZF:OTCQB; J0G:FSE
tan Astronomers find a golden glow from a distant stellar collision By news.science360.gov Published On :: 2019-08-30T07:00:00Z Full Text:On August 17, 2017, scientists made history with the first direct observation of a merger between two neutron stars. It was the first cosmic event detected in both gravitational waves and the entire spectrum of light, from gamma rays to radio emissions. The impact also created a kilonova -- a turbocharged explosion that instantly forged several hundred planets’ worth of gold and platinum. The observations provided the first compelling evidence that kilonovae produce large quantities of heavy metals, a finding long predicted by theory. Astronomers suspect that all of the gold and platinum on Earth formed as a result of ancient kilonovae created during neutron star collisions. Based on data from the 2017 event, first spotted by the Laser Interferometer Gravitational-wave Observatory (LIGO), astronomers began to adjust their assumptions of how a kilonova should appear to Earth-bound observers. A team of scientists reexamined data from a gamma-ray burst spotted in August 2016 and found new evidence for a kilonova that went unnoticed during the initial observations.Image credit: NASA/ESA/E. Troja Full Article