ace Barbara Brizuela Embraces Interdisciplinarity as Dean of the School of Arts and Sciences By www.newswise.com Published On :: Mon, 04 Nov 2024 13:50:52 EST Barbara Brizuela, who has been named dean of the School of Arts and Sciences, is a big believer in interdisciplinary research. "Knowledge-seeking has no disciplinary boundaries," says Brizuela. "We're going to need broad and connected perspectives to be able to solve the world's biggest problems." The dean of the Graduate School of Arts and Sciences (GSAS) and professor of education served as the school's dean ad interim since July. Her appointment to lead the School of Arts and Sciences builds on a long and distinguished career as a teacher, mentor, researcher, and administrator. Full Article
ace How Identity Impacts Bystander Responses to Workplace Mistreatment By www.newswise.com Published On :: Wed, 06 Nov 2024 09:45:47 EST Full Article
ace JCS Warns N. Korea Will Face Corresponding Steps if It Infiltrates Drones By world.kbs.co.kr Published On :: Mon, 28 Oct 2024 17:41:20 +0900 [Inter-Korea] : The Joint Chiefs of Staff(JCS) has warned that North Korea will face corresponding countermeasures if it infiltrates drones into South Korean territory. JCS spokesperson Lee Sung-joon unveiled such a stance to reporters on Monday when asked to comment on Kim Yo-jong, the sister of North Korean leader Kim ...[more...] Full Article Inter-Korea
ace Sports Ministry: Badminton Korea Association Leader Could Face Embezzlement Charges By world.kbs.co.kr Published On :: Tue, 10 Sep 2024 15:29:07 +0900 [Sports] : The Ministry of Culture, Sports and Tourism says it has uncovered evidence of financial misconduct at the Badminton Korea Association(BKA). During a briefing on an ongoing investigation Tuesday, the ministry said it suspects the head of the association and another top official improperly distributed 150 ...[more...] Full Article Sports
ace Men's Football Team to Face Jordan in World Cup Qualifier without Captain Son By world.kbs.co.kr Published On :: Thu, 10 Oct 2024 14:54:45 +0900 [Sports] : The South Korean men's national football team is set to face Jordan in the third round of 2026 FIFA World Cup qualifiers. The qualifying match between the national team, led by head coach Hong Myung-bo, and Jordan at Amman International Stadium is scheduled to begin at 11 p.m. Thursday, Korea time. While ...[more...] Full Article Sports
ace Men's National Football Team Face Iraq in World Cup Qualifier By world.kbs.co.kr Published On :: Tue, 15 Oct 2024 15:15:11 +0900 [Sports] : The South Korean men's national football team faces Iraq in the World Cup qualifier match on Tuesday night at home. Considered the toughest opponent for South Korea in the third round of the Asian qualifiers, a win against the Middle Eastern squad will give the Taegeuk Warriors a huge boost in their ...[more...] Full Article Sports
ace Son Heung-min Returns as National Team Faces Kuwait, Palestine in World Cup Qualifiers By world.kbs.co.kr Published On :: Mon, 04 Nov 2024 15:51:08 +0900 [Sports] : The men’s national football team is set to face Kuwait and Palestine in mid-November in the third round of 2026 FIFA World Cup qualifiers with the return of captain Son Heung-min, who sat out matches in October due to a hamstring injury. Head coach Hong Myung-bo announced the 26-member roster on Monday, ...[more...] Full Article Sports
ace Heavy Rain Warning and Watch in place For Most Parts of Nation By world.kbs.co.kr Published On :: Fri, 20 Sep 2024 17:44:26 +0900 [Science] : A heavy rain warning has been issued for the five border islands in the Yellow Sea and a heavy rain watch for the Seoul metro area, Gangwon Province and parts of the Jeolla and Gyeongsang provinces. With heavy rain set to pound most parts of the nation through Sunday, the interior and safety ministry on ...[more...] Full Article Science
ace 38% of Tree Species Face Extinction Due to Climate Change, Deforestation By world.kbs.co.kr Published On :: Wed, 30 Oct 2024 14:23:05 +0900 [Science] : More than a third of all tree species around the world face extinction due largely to climate change and deforestation. Citing a report from the International Union for the Conservation of Nature(IUCN), CBS News said 38 percent of tree species are at risk, threatening ecosystems, plants, animals and ...[more...] Full Article Science
ace S. Korea, US to Launch Solar Observation Instrument to Int’l Space Station By world.kbs.co.kr Published On :: Fri, 01 Nov 2024 14:15:21 +0900 [Science] : South Korea and the United States will launch a jointly developed instrument to the International Space Station(ISS) to help scientists learn more about the solar wind. According to the Korea AeroSpace Administration and the Korea Astronomy and Space Science Institute, the Coronal Diagnostic ...[more...] Full Article Science
ace Space Agency to Develop Lunar Module to be Sent to Moon by 2032 By world.kbs.co.kr Published On :: Mon, 04 Nov 2024 17:44:41 +0900 [Science] : The Korea AeroSpace Administration and the Korea Aerospace Research Institute are set to proceed with the development of a lunar module after signing an agreement on the second phase of the nation’s moon exploration project. According to the state agency on Monday, some 530 billion won, or around 386 ...[more...] Full Article Science
ace S. Korea’s Telecom Satellite Koreasat-6A Launched from US Space Center By world.kbs.co.kr Published On :: Tue, 12 Nov 2024 09:48:52 +0900 [Science] : A telecommunication satellite from the South Korean telecom giant KT has been launched into space and is now in orbit. According to a launch video from SpaceX, the Koreasat-6A, a geostationary satellite for communication services, was launched aboard SpaceX’s Falcon 9 rocket from the Kennedy Space ...[more...] Full Article Science
ace 4 Facebook Marketplace Scams and How to Protect Yourself By money.howstuffworks.com Published On :: Wed, 07 Aug 2024 10:15:02 -0400 Facebook Marketplace has become a popular platform for buying and selling goods, from used cars to gaming systems. However, as with any online marketplace, it has also become a breeding ground for scams. Full Article
ace Which Places Have a Blue and Yellow Flag? There Are at Least 8 By people.howstuffworks.com Published On :: Fri, 08 Nov 2024 10:00:04 -0500 Blue and yellow flags are common among national and state flags, and the blue and yellow color combinations often symbolize nature. Full Article
ace RM Releases 2nd Solo Album 'Right Place, Wrong Person' By world.kbs.co.kr Published On :: 2024-05-24 RM of BTS released his second solo album 'Right Place, Wrong Person' on Friday, his first solo album since 'Indigo' in December 2022.The album carries eleven songs, including the title track...[more...] Full Article
ace When Was Soccer Invented? Roots Trace Back Over 2,000 Years By entertainment.howstuffworks.com Published On :: Thu, 07 Nov 2024 10:10:02 -0500 Soccer, football — no matter what you call it, the world's most popular sport has a long and colorful history, from its ancient origins to its modern-day status as a global phenomenon. But when was soccer invented? How did it become the "beautiful game" that captivates millions today? Full Article
ace Ace of Swords Reversed: Symbolism and Spiritual Implications By entertainment.howstuffworks.com Published On :: Tue, 12 Nov 2024 05:00:03 -0500 Discover the meaning of the Ace of Swords reversed in tarot. Explore its insights on clarity, communication, and inner conflicts in love, career, and personal growth. Full Article
ace What Does the Ace of Cups Reversed Mean in Your Tarot Reading? By entertainment.howstuffworks.com Published On :: Wed, 13 Nov 2024 05:00:04 -0500 Is Ace of Cups Reversed" reveals insights into blocked emotions and self-reflection in tarot readings, offering guidance on relationships and personal growth. Full Article
ace Washington DC among US cities most vulnerable to space weather, scientists say - The Royal Astronomical Society By news.google.com Published On :: Thu, 18 Jul 2024 07:00:00 GMT Washington DC among US cities most vulnerable to space weather, scientists say The Royal Astronomical Society Full Article
ace Studying multi-hazards from space - British Geological Survey By news.google.com Published On :: Fri, 31 May 2024 08:09:03 GMT Studying multi-hazards from space British Geological Survey Full Article
ace Monitoring coastal change from space - British Geological Survey By news.google.com Published On :: Thu, 10 Oct 2024 14:36:15 GMT Monitoring coastal change from space British Geological Survey Full Article
ace 2024 BGS summer placements scheme - British Geological Survey By news.google.com Published On :: Mon, 27 May 2024 16:11:34 GMT 2024 BGS summer placements scheme British Geological Survey Full Article
ace New community launched to support effective management of the subsurface - British Geological Survey By news.google.com Published On :: Thu, 03 Oct 2024 13:27:24 GMT New community launched to support effective management of the subsurface British Geological Survey Full Article
ace Tracking anharmonic oscillations in the structure of β 1,3-diacetylpyrene By journals.iucr.org Published On :: A recently discovered β polymorph of 1,3-diacetylpyrene has turned out to be a prominent negative thermal expansion material. Its unique properties can be linked to anharmonic oscillations in the crystal structure. The onset and development of anharmonic behavior have been successfully tracked over a wide temperature range by single-crystal X-ray diffraction experiments. Sufficient diffraction data quality combined with modern quantum crystallography tools allowed a thorough analysis of the elusive anharmonic effects for a moderate-scattering purely organic compound. Full Article text
ace Morphological control for hollow rod crystals of a photochromic diarylethene on spherulites by surface properties of substrates By journals.iucr.org Published On :: 1,2-Bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene formed its own spherulites by sublimation onto the hydrophilic surfaces of the (0001) planes of α-quartz and sapphire substrates. The formation of different morphologies of these spherulites was attributed to the surface properties of each substrate. Depending on the morphology of the spherulites, hollow rod crystals with cross sections of different sizes and shapes and branching structures were generated on the surfaces of the spherulites. Full Article text
ace Morphological control for hollow rod crystals of a photochromic diarylethene on spherulites by surface properties of substrates By journals.iucr.org Published On :: 2024-10-31 Sublimation methods utilizing the surface properties of substrates can address the challenge of controlling hollow morphologies in rod crystals. Spherulites were formed on the hydrophilic surface of the (0001) planes of α-quartz and sapphire substrates by sublimation of 1,2-bis(3,5-dimethyl-2-thienyl)perfluorocyclopentene (1a). Various types of hollow morphologies, distinguished by the size and shape of their cross sections and by the presence or absence of branching structures, were formed separately on α-quartz and sapphire substrates. Such precise control of the hollow morphologies was attributed to the wettability of each substrate, leading to the formation of spherulites of 1a. In addition, it was indicated that the formation process of the surface morphologies of spherulites was associated with the hollow morphologies of rod crystals of 1a. Full Article text
ace Crystal structures of three uranyl–acetate–bipyridine complexes crystallized from hydraulic fracking fluid By journals.iucr.org Published On :: 2024-01-01 Hydraulic fracking exposes shale plays to acidic hydraulic fracking fluid (HFF), releasing toxic uranium (U) along with the desired oil and gas. With no existing methods to ensure U remains sequestered in the shale, this study sought to add organic ligands to HFF to explore potential U retention in shale plays. To test this possibility, incubations were set up in which uranyl acetate and one organic bipyridine ligand (either 2,2'-, 2,3'-, 2,4'-, or 4,4'-bipyridine) were added to pristine HFF as the crystallization medium. After several months and complete evaporation of all volatiles, bulk yellow crystalline material was obtained from the incubations, three of which yielded crystals suitable for single-crystal analysis, resulting in two novel structures and a high-quality structure of a previously described compound. The UO2VI acetate complexes bis(acetato-κ2O,O')(2,2'-bipyridine-κ2N,N')dioxidouranium(VI), [U(C2H3O2)2O2(C10H8N2)2] or [2,2'-bipyridine]UVIO2(CH3CO2)2, (I), and bis(acetato-κ2O,O')(2,4'-bipyridine-κN1')dioxidouranium(VI), [U(C2H3O2)2O2(C10H8N2)2] or [2,4'-bipyridine]2UVIO2(CH3CO2)2, (III), contain eight-coordinate UVI in a pseudo-hexagonal bipyramidal coordination geometry and are molecular, packing via weak C—H...O/N interactions, whereas catena-poly[bis(2,3'-bipyridinium) [di-μ-acetato-μ3-hydroxido-μ-hydroxido-di-μ3-oxido-hexaoxidotriuranium(VI)]–2,3'-bipyridine–water (1/1/1)], (C10H9N2)2[U3(C2H3O2)2O8(OH)2]·C10H8N2·H2O or {[2,3'-bipyridinium]2[2,3'-bipyridine][(UVIO2)3(O)2(OH)2(CH3CO2)2·H2O]}n, (II), forms an ionic one-dimensional polymer with seven-coordinate pentagonal bipyramidal UVI centers and hydrogen-bonding interactions within each chain. The formation of these crystals could indicate the potential for bipyridine to bind with U in shale during fracking, which will be explored in a future study via ICP-MS (inductively coupled plasma mass spectrometry) analyses of U concentration in HFF/bipyridine/shale incubations. The variation seen here between the molecular structures may indicate variance in the ability of bipyridine isomers to form complexes with U, which could impact their ability to retain U within shale in the context of fracking. Full Article text
ace GraphT–T (V1.0Beta), a program for embedding and visualizing periodic graphs in 3D Euclidean space By journals.iucr.org Published On :: 2024-04-29 Following the work of Day & Hawthorne [Acta Cryst. (2022), A78, 212–233] and Day et al. [Acta Cryst. (2024), A80, 258–281], the program GraphT–T has been developed to embed graphical representations of observed and hypothetical chains of (SiO4)4− tetrahedra into 2D and 3D Euclidean space. During embedding, the distance between linked vertices (T–T distances) and the distance between unlinked vertices (T⋯T separations) in the resultant unit-distance graph are restrained to the average observed distance between linked Si tetrahedra (3.06±0.15 Å) and the minimum separation between unlinked vertices is restrained to be equal to or greater than the minimum distance between unlinked Si tetrahedra (3.713 Å) in silicate minerals. The notional interactions between vertices are described by a 3D spring-force algorithm in which the attractive forces between linked vertices behave according to Hooke's law and the repulsive forces between unlinked vertices behave according to Coulomb's law. Embedding parameters (i.e. spring coefficient, k, and Coulomb's constant, K) are iteratively refined during embedding to determine if it is possible to embed a given graph to produce a unit-distance graph with T–T distances and T⋯T separations that are compatible with the observed T–T distances and T⋯T separations in crystal structures. The resultant unit-distance graphs are denoted as compatible and may form crystal structures if and only if all distances between linked vertices (T–T distances) agree with the average observed distance between linked Si tetrahedra (3.06±0.15 Å) and the minimum separation between unlinked vertices is equal to or greater than the minimum distance between unlinked Si tetrahedra (3.713 Å) in silicate minerals. If the unit-distance graph does not satisfy these conditions, it is considered incompatible and the corresponding chain of tetrahedra is unlikely to form crystal structures. Using GraphT–T, Day et al. [Acta Cryst. (2024), A80, 258–281] have shown that several topological properties of chain graphs influence the flexibility (and rigidity) of the corresponding chains of Si tetrahedra and may explain why particular compatible chain arrangements (and the minerals in which they occur) are more common than others and/or why incompatible chain arrangements do not occur in crystals despite being topologically possible. Full Article text
ace Room-temperature serial synchrotron crystallography structure of Spinacia oleracea RuBisCO By journals.iucr.org Published On :: 2024-05-29 Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) is the enzyme responsible for the first step of carbon dioxide (CO2) fixation in plants, which proceeds via the carboxylation of ribulose 1,5-biphosphate. Because of the enormous importance of this reaction in agriculture and the environment, there is considerable interest in the mechanism of fixation of CO2 by RuBisCO. Here, a serial synchrotron crystallography structure of spinach RuBisCO is reported at 2.3 Å resolution. This structure is consistent with earlier single-crystal X-ray structures of this enzyme and the results are a good starting point for a further push towards time-resolved serial synchrotron crystallography in order to better understand the mechanism of the reaction. Full Article text
ace Duality of spaces and the origin of integral reflection conditions By journals.iucr.org Published On :: The reciprocal of a non-primitive unit cell is not a unit cell and the basis vectors do not correspond to cell lengths. Full Article text
ace Animations, videos and 3D models for teaching space-group symmetry By journals.iucr.org Published On :: Animations, videos and 3D models have been designed to visualize the effects of symmetry operators on selected cases of crystal structures, pointing out the relationship with the diagrams published in International Tables for Crystallography, Vol. A. Full Article text
ace Crystal structure and Hirshfeld surface analysis of bis(benzoylacetonato)(ethanol)dioxidouranium(VI) By journals.iucr.org Published On :: In the complex, the ligand binds to the metal through an oxygen atom. The geometry of the seven-coordinate U atom is pentagonal bipyramidal, with the uranyl O atoms in apical positions. Full Article text
ace Crystal structure and Hirshfeld-surface analysis of an etoxazole metabolite designated R13 By journals.iucr.org Published On :: The crystal structure of a metabolite of the insecticide/acaricide etoxazole, designated R13 is presented along with a Hirshfeld surface analysis of intermolecular interactions present in the crystal structure. Full Article text
ace Crystal structure, Hirshfeld surface analysis, DFT and molecular docking studies of ethyl 5-amino-2-bromoisonicotinate By journals.iucr.org Published On :: Theoretical and experimental structural studies of the title compound were undertaken using X-ray and DFT methods. The interactions present in the crystal were analyzed using Hirshfeld surface and MEP surface analysis. Docking studies with a covid-19 main protease (PDB ID: 6LU7) as the target receptor indicate that the synthesized compound may be a potential candidate for pharmaceutical applications. Full Article text
ace Crystal structure, Hirshfeld surface, DFT and molecular docking studies of 2-{4-[(E)-(4-acetylphenyl)diazenyl]phenyl}-1-(5-bromothiophen-2-yl)ethanone; a bromine⋯oxygen type contact By journals.iucr.org Published On :: The title compound is a non-liquid crystal molecule. The molecular crystal is consolidated by C—Br⋯O&z-dbnd;C type contacts running continuously along the [001] direction. Full Article text
ace Synthesis, crystal structure and Hirshfeld surface analysis of N-(4-methoxyphenyl)picolinamide By journals.iucr.org Published On :: The molecular and crystal structure of N-(4-methoxyphenyl)picolinamide were studied and Hirshfeld surfaces and fingerprint plots were generated to investigate various intermolecular interactions. Full Article text
ace Animations, videos and 3D models for teaching space-group symmetry By journals.iucr.org Published On :: 2024-10-16 A series of animations, videos and 3D models that were developed, filmed or built to teach the symmetry properties of crystals are described. At first, these resources were designed for graduate students taking a basic crystallography course, coming from different careers, at the National Autonomous University of Mexico. However, the COVID-19 pandemic had the effect of accelerating the generation of didactic material. Besides our experience with postgraduate students, we have noted that 3D models attract the attention of children, and therefore we believe that these models are particularly useful for teaching children about the assembled arrangements of crystal structures. Full Article text
ace Duality of spaces and the origin of integral reflection conditions By journals.iucr.org Published On :: 2024-10-16 The dualism between direct and reciprocal space is at the origin of well known relations between basis vectors in the two spaces. It is shown that when a coordinate system corresponding to a non-primitive unit cell is adopted, this dualism has to be handled with care. In particular, the reciprocal of a non-primitive unit cell is not a unit cell but a region in reciprocal space that does not represent a unit of repetition by translation. The basis vectors do not correspond to reciprocal-space cell lengths, contrary to what is stated even in the core CIF dictionary. The corresponding unit cell is a multiple of this region. The broken correspondence between basis vectors and unit cell is at the origin of the integral reflection conditions. Full Article text
ace Structure of face-centred icosahedral quasicrystals with cluster close packing By journals.iucr.org Published On :: 2024-09-30 A 6D structure model for face-centred icosahedral quasicrystals consisting of so-called pseudo-Mackay and mini-Bergman-type atomic clusters is proposed based on the structure model of the Al69.1Pd22Cr2.1Fe6.8 3/2 cubic approximant crystal (with space group Pa3, a = 40.5 Å) [Fujita et al. (2013). Acta Cryst. A69, 322–340]. The cluster centres form an icosahedral close sphere packing generated by the occupation domains similar to those in the model proposed by Katz & Gratias [J. Non-Cryst. Solids (1993), 153–154, 187–195], but their size is smaller by a factor τ2 [τ = (1 + (5)1/2)/2]. The clusters cover approximately 99.46% of the atomic structure, and the cluster arrangement exhibits 15 and 19 different local configurations, respectively, for the pseudo-Mackay and mini-Bergman-type clusters. The occupation domains that generate cluster shells are modelled and discussed in terms of structural disorder and local reorganization of the cluster arrangements (phason flip). Full Article text
ace Crystal structure, Hirshfeld surface analysis, DFT and molecular docking studies of ethyl 5-amino-2-bromoisonicotinate By journals.iucr.org Published On :: 2024-11-08 In the title compound, C8H9BrN2O2, the C—O—C—C torsion angle between isonicotine and the ethyl group is 180.0 (2)°. Intramolecular N—H...O and C—H...O interactions consolidate the molecular structure. In the crystal, N—H...N interaction form S(5) zigzag chains along [010]. The most significant contributions to the Hirshfeld surface arise from H...H (33.2%), Br...H/H...Br (20.9%), O...H/H...O (11.2%), C...H/H...C (11.1%) and N...H/H...N (10%) contacts. The topology of the three-dimensional energy frameworks was generated using the B3LYP/6–31 G(d,p) model to calculate the total interaction energy. The net interaction energies for the title compound are Eele = 59.2 kJ mol−1, Epol = 15.5 kJ mol−1, Edis = 140.3 kJ mol−1 and Erep = 107.2 kJ mol−1 with a total interaction energy Etot of 128.8 kJ mol−1. The molecular structure was optimized by density functional theory (DFT) at the B3LYP/6–311+G(d,p) level and the theoretical and experimentally obtained parameters were compared. The frontier molecular orbitals HOMO and LUMO were generated, giving an energy gap ΔE of 4.0931 eV. The MEP was generated to identify active sites in the molecule and molecular docking studies carried out with the title compound (ligand) and the covid-19 main protease PDB ID: 6LU7, revealing a moderate binding affinity of −5.4 kcal mol−1. Full Article text
ace Crystal structure and Hirshfeld-surface analysis of an etoxazole metabolite designated R13 By journals.iucr.org Published On :: 2024-11-08 The etoxazole metabolite R13, systematic name 4-(4-tert-butyl-2-ethoxyphenyl)-2-(2,6-difluorophenyl)oxazole (C21H21F2NO2), results from the oxidation of etoxazole, a chitin synthesis inhibitor belonging to the oxazoline class, widely used as an insecticide/acaricide since 1998. The structure of R13 features a central oxazole ring with attached 2,6-difluorophenyl and 4-t-butyl-2-ethoxyphenyl moieties. The overall conformation gives dihedral angles between these rings and the oxazole of 24.91 (5)° (with difluorophenyl) and 15.30 (6)° (with t-butyl-ethoxyphenyl), indicating an overall deviation from planarity. Additionally, torsion angles of the ethoxy and t-butyl groups define the orientation of these substituents relative to their benzene ring. In the crystal packing, no significant hydrogen bonds are present, but a Hirshfeld surface analysis highlights weak intermolecular contacts leading to π–π-stacked dimers linked by weak C—H...N contacts. The packing analysis confirms that most intermolecular interactions involve hydrogen atoms. Full Article text
ace Performance of a photoelectron momentum microscope in direct- and momentum-space imaging with ultraviolet photon sources By journals.iucr.org Published On :: 2024-01-01 The Photoelectron-Related Image and Nano-Spectroscopy (PRINS) endstation located at the Taiwan Photon Source beamline 27A2 houses a photoelectron momentum microscope capable of performing direct-space imaging, momentum-space imaging and photoemission spectroscopy with position sensitivity. Here, the performance of this microscope is demonstrated using two in-house photon sources – an Hg lamp and He(I) radiation – on a standard checkerboard-patterned specimen and an Au(111) single crystal, respectively. By analyzing the intensity profile of the edge of the Au patterns, the Rashba-splitting of the Au(111) Shockley surface state at 300 K, and the photoelectron intensity across the Fermi edge at 80 K, the spatial, momentum and energy resolution were estimated to be 50 nm, 0.0172 Å−1 and 26 meV, respectively. Additionally, it is shown that the band structures acquired in either constant energy contour mode or momentum-resolved photoemission spectroscopy mode were in close agreement. Full Article text
ace Similarity score for screening phase-retrieved maps in X-ray diffraction imaging – characterization in reciprocal space By journals.iucr.org Published On :: 2024-01-01 X-ray diffraction imaging (XDI) is utilized for visualizing the structures of non-crystalline particles in material sciences and biology. In the structural analysis, phase-retrieval (PR) algorithms are applied to the diffraction amplitude data alone to reconstruct the electron density map of a specimen particle projected along the direction of the incident X-rays. However, PR calculations may not lead to good convergence because of a lack of diffraction patterns in small-angle regions and Poisson noise in X-ray detection. Therefore, the PR calculation is still a bottleneck for the efficient application of XDI in the structural analyses of non-crystalline particles. For screening maps from hundreds of trial PR calculations, we have been using a score and measuring the similarity between a pair of retrieved maps. Empirically, probable maps approximating the particle structures gave a score smaller than a threshold value, but the reasons for the effectiveness of the score are still unclear. In this study, the score is characterized in terms of the phase differences between the structure factors of the retrieved maps, the usefulness of the score in screening the maps retrieved from experimental diffraction patterns is demonstrated, and the effective resolution of similarity-score-selected maps is discussed. Full Article text
ace Investigating the missing-wedge problem in small-angle X-ray scattering tensor tomography across real and reciprocal space By journals.iucr.org Published On :: 2024-08-28 Small-angle-scattering tensor tomography is a technique for studying anisotropic nanostructures of millimetre-sized samples in a volume-resolved manner. It requires the acquisition of data through repeated tomographic rotations about an axis which is subjected to a series of tilts. The tilt that can be achieved with a typical setup is geometrically constrained, which leads to limits in the set of directions from which the different parts of the reciprocal space map can be probed. Here, we characterize the impact of this limitation on reconstructions in terms of the missing wedge problem of tomography, by treating the problem of tensor tomography as the reconstruction of a three-dimensional field of functions on the unit sphere, represented by a grid of Gaussian radial basis functions. We then devise an acquisition scheme to obtain complete data by remounting the sample, which we apply to a sample of human trabecular bone. Performing tensor tomographic reconstructions of limited data sets as well as the complete data set, we further investigate and validate the missing wedge problem by investigating reconstruction errors due to data incompleteness across both real and reciprocal space. Finally, we carry out an analysis of orientations and derived scalar quantities, to quantify the impact of this missing wedge problem on a typical tensor tomographic analysis. We conclude that the effects of data incompleteness are consistent with the predicted impact of the missing wedge problem, and that the impact on tensor tomographic analysis is appreciable but limited, especially if precautions are taken. In particular, there is only limited impact on the means and relative anisotropies of the reconstructed reciprocal space maps. Full Article text
ace Bis[μ-bis(pyridin-2-yl)methanone oxime-κ3N:,N',N'']bis[diacetato-κ2O,O';κO-zinc(II)] By journals.iucr.org Published On :: 2024-02-16 The structure of the title complex, [Zn2(C2H3O2)4(C11H9N3O)2], is triclinic containing half of the molecule in the asymmetric unit. Each zinc atom is coordinated to a pyridyl and oxime nitrogen from one di-2-pyridyl ketone oxime (dpko) ligand and a third nitrogen from the other dpko pyridyl ring. Additionally, each zinc is coordinated to two acetato anions, one of which is bidentate and the other monodentate. The uncoordinated oxygen of the monodentate acetato group is involved in a hydrogen bond with the oxime hydrogen. The packing in the crystal is assisted by weak C—H⋯O interactions between acetato groups and neighboring pyridyl rings. Full Article text
ace 10-Bromo-N,N-diphenylanthracen-9-amine By journals.iucr.org Published On :: 2024-03-12 In the title compound, C26H18BrN, the dihedral angles between the anthracene ring system and the phenyl rings are 89.51 (14) and 74.03 (15)°. In the extended structure, a weak C—H⋯Br interaction occurs, which generates [100] chains, but no significant π–π or C—H⋯π interactions are observed. Full Article text
ace 2-(10-Bromoanthracen-9-yl)-N-phenylaniline By journals.iucr.org Published On :: 2024-05-31 In the title compound, C26H18BrN, the central benzene ring makes dihedral angles with its adjacent anthracene ring system and pendant benzene ring of 87.49 (13) and 62.01 (17)°, respectively. The N—H moiety is sterically blocked from forming a hydrogen bond, but weak C—H⋯π interactions occur in the extended structure. Full Article text
ace Triacetonitrile(1,4,7-trimethyl-1,4,7-triazacyclononane)cobalt(II) bis(tetraphenylborate) By journals.iucr.org Published On :: 2024-06-11 The title cobalt(II) complex, [Co(C2H3N)3(C9H21N3)](C24H20B)2 or [(tacn)Co(NCMe)3][BPh4]2, has been characterized by single-crystal X-ray diffraction. It incorporates the well-known macrocyclic tacn (1,4,7-trimethyl-1,4,7-triazacyclononane) ligand, which is coordinated facially to the metal center. The complex crystallizes in space group P21/c with Z = 4. The divalent cobalt ion exhibits a six-coordinate octahedral geometry by one tacn and three acetonitrile ligands. Two non-coordinating tetraphenylborate (BPh4−) anions are also present. Full Article text
ace Poly[[μ3-2-(benzotriazol-1-yl)acetato-κ3O:O':N3]chlorido(ethanol-κO)cobalt(II)] By journals.iucr.org Published On :: 2024-07-05 In the title compound, [Co(C8H6N3O2)Cl(C2H5OH)]n, the CoII atoms adopt octahedral trans-CoN2O4 and tetrahedral CoCl2O2 coordination geometries (site symmetries overline{1} and m, respectively). The bridging μ3-O:O:N 2-(benzotriazol-1-yl)acetato ligands connect the octahedral cobalt nodes into (010) sheets and the CoCl2 fragments link the sheets into a tri-periodic network. The structure displays O—H⋯O hydrogen bonding and the ethanol molecule is disordered over two orientations. Full Article text
ace [1-(Anthracen-9-ylmethyl)-1,4,7,10-tetraazacyclododecane]chloridozinc(II) nitrate By journals.iucr.org Published On :: 2024-07-12 In the title salt, [ZnCl(C23H30N4)]NO3, the central ZnII atom of the complex cation is coordinated in a square-pyramidal arrangement by four nitrogen atoms from cyclen (1,4,7,10-tetraazacyclododecane) in the basal plane and one chlorido ligand in the apical position. The anthracene group attached to cyclen contributes to the crystal packing through intermolecular T-shaped π interactions. Additionally, the nitrate anion participates in intermolecular N—H⋯O hydrogen bonds with cyclen. Full Article text