diff Education Indicators in Focus No. 54 - Transition from school to work: How hard is it across different age groups? By dx.doi.org Published On :: Thu, 31 Aug 2017 20:07:00 GMT The transition from school to work can be a difficult period associated with spells of unemployment. Data show that those who leave school early have comparatively low skills and low educational attainment and face the greatest challenges in the labour market compared to their peers who stayed in education longer. Full Article
diff Different, not disabled: Neurodiversity in education (OECD Education Today Blog) By oecdeducationtoday.blogspot.com Published On :: Wed, 11 Oct 2017 12:10:00 GMT Diversity in the classroom includes differences in the way students brains learn, or neurodiversity. Diagnoses of neurodevelopmental disorders such as autism spectrum disorder (ASD) and attention deficit hyperactive disorder (ADHD) have risen dramatically in the last two decades. Full Article
diff Education Indicators in Focus N° 55 - What are the gender differences and the labour market outcomes across the different fields of study? By dx.doi.org Published On :: Tue, 31 Oct 2017 11:41:00 GMT Although girls and boys perform similarly in the PISA science assessment at age 15, girls are less likely than boys to envision a career in science and engineering, even in countries where they outperform them. Full Article
diff Local logic: How cities can make a difference By www.oecd.org Published On :: Tue, 26 Apr 2016 18:04:00 GMT The world cannot resolve today’s development challenges with purely national approaches. We need to complement them with local approaches, too. We live in an era of enormous transformations, in which our traditional political structures and forms of democratic participation must adapt. That means casting a bigger focus than ever on the important role of local power and communities. Full Article
diff Webinar video recording on Finding Alternatives to Per- and Polyfluoroalkyl Substances of Concern: A Difficult and Continuing Challenge By www.oecd.org Published On :: Mon, 07 Oct 2019 16:40:00 GMT On Thursday 26 September 2019, the OECD discussed "Finding Alternatives to Per- and Polyfluoroalkyl Substances of Concern: A Difficult and Continuing Challenge" with the participation of W.L. Gore & Associates, Inc. Presenters shared efforts, successes and challenges in eliminating per and polyfluorinated chemicals of environmental concern from the life cycle of consumer products. Full Article
diff The Fast Lane: Design that’s in a different class By www.ft.com Published On :: Fri, 03 Nov 2017 15:12:03 GMT Is Bombardier C Series the plane business travellers have been waiting for? Full Article
diff Top Tips for trading contracts for difference By www.ft.com Published On :: Tue, 20 Dec 2011 13:49:18 GMT Ten ways to improve your chances when placing a bet Full Article
diff Different speed cameras explained: The 15 types used in Britain By www.dailymail.co.uk Published On :: Wed, 27 Feb 2019 07:57:40 GMT Do you know your Gatso from your HADECS? Can you tell which are fixed smart motorways cameras and average speed monitors? Take our quiz and find out which ones you need to look out for. Full Article
diff It's capricious and difficult but there's no denying Pinot Noir is worth celebrating By www.dailymail.co.uk Published On :: Sat, 17 Aug 2019 21:01:43 GMT Happy Pinot Noir Day (yes, it really is a thing). I'm up for a bit of veneration - any excuse to celebrate the good things in life, and Pinot Noir is among the best Full Article
diff Derby 1-1 Cardiff: Robert Glatzel penalty cancels out Scott Malone's early opener By www.dailymail.co.uk Published On :: Fri, 13 Sep 2019 23:00:33 GMT ADAM SHERGOLD AT PRIDE PARK: The ground was evacuated half-an-hour before kick-off when Cardiff fans set off smoke flares. But it's Derby's season that refuses to ignite. Full Article
diff Future of live music will be different for a while: Bono By www.business-standard.com Published On :: Sun, 10 May 2020 10:10:53 +0530 U2 frontman Bono believes the future of live gigs looks "very different" as the world struggles to recover from the coronavirus pandemic. According to Contactmusic, the singer said drive-in shows can be a successful alternative as there is a possibility to maintain social distancing. "I think it will be very different for a while. I heard discussion of sort of drive-in type shows. "Outside the stadiums, you have these big (parking lots) -- so setting up drive-ins, where you have bands playing live from their rehearsal rooms," Bono said. The 59-year-old singer, whose real name is Paul David Hewson, is happy that his band was able to finish of its tour before the lockdown. "We haven't learned to phone in our shows. They're full-tilt for us," he said. Full Article
diff A different destiny in writing By indiatogether.org Published On :: Mon, 08 Apr 2013 00:00:00 +0000 Among the steadily growing voices expressing their angst against discrimination, suppression and abuse of women, those of Indian feminist writers are fast gaining in pitch and range. Abha Sharma captures some of these. Full Article
diff Dying of indifference By indiatogether.org Published On :: Fri, 10 Sep 2010 00:00:00 +0000 One woman dies every eight minutes due to complications arising due to pregnancy such as sepsis, haemorrhage or obstructed labour. These deaths could be avoided if there is timely medical intervention, writes Kalpana Sharma. Full Article
diff Rainbow children : dissolving differences By indiatogether.org Published On :: Wed, 01 Oct 2003 00:00:00 +0000 Since 1979, this Kolkata school has pioneered an educational process where kids from different economic and social sections of society study, play and share together as equals. Full Article
diff Absolutely love the IPL, has a different atmosphere: Virat Kohli By timesofindia.indiatimes.com Published On :: Sun, 10 May 2020 10:41:34 IST The camaraderie that players share during the Indian Premier League (IPL) is what makes the tournament special for India and Royal Challengers Bangalore (RCB) captain Virat Kohli. He would have been leading RCB in the 2020 edition of the T20 league at this time, had it not been for the coronavirus pandemic forcing the postponement of the IPL until further notice. Full Article
diff ‘Different vaccines being tried out, will take at least 6 months’ By timesofindia.indiatimes.com Published On :: Sun, 10 May 2020 04:29:00 IST Full Article
diff JMM, Cong differ over fee waivers by pvt schools By timesofindia.indiatimes.com Published On :: Sun, 10 May 2020 05:00:00 IST Full Article
diff Valentia: a different Irish island / by Nellie O'Cleirigh By library.mit.edu Published On :: Sun, 26 Jan 2014 06:36:43 EST Archives, Room Use Only - DA990.V34 O25 1992 Full Article
diff Bentley's complete phrase code: (nearly 1000 million combinations): with at least 2 letters difference between each half-code word / compiled by E.L. Bentley By library.mit.edu Published On :: Sun, 25 May 2014 06:33:02 EDT Archives, Room Use Only - HE7673.B46 1923 Full Article
diff Library of useful knowledge / published under the superintendence of the Society for the Diffusion of Useful Knowledge By library.mit.edu Published On :: Sun, 31 Aug 2014 08:18:07 EDT Archives, Room Use Only - QC21.L53 1827b Full Article
diff Scientific tracts, for the diffusion of useful knowledge ...: complete in one volume. By library.mit.edu Published On :: Sun, 21 Sep 2014 08:20:08 EDT Archives, Room Use Only - Q171.S42 1836 Full Article
diff 'A very difficult shot': Yuvraj Singh shares video of him hitting six over covers By www.newkerala.com Published On :: Sat, 09 May 2020 21:02:02 +0530 Full Article
diff Britney Spears thanks fans with radically different new cover for 2016's 'Glory' By www.newkerala.com Published On :: Sun, 10 May 2020 01:42:01 +0530 Full Article
diff Nick Saban explains differences in Jerry Jeudy, Raiders' Henry Ruggs By sports.yahoo.com Published On :: Sun, 10 May 2020 00:02:09 GMT Nick Saban doesn't want to choose between his two best wide receivers from a year ago. Full Article article News
diff Flame retardants have different effects at high and low doses By feedproxy.google.com Published On :: Tue, 19 Jan 2010 10:00:00 EDT A proteomic study reveals wide-ranging protein differences among brain cells treated with various concentrations of PBDE-99. Full Article
diff Publicise helpline number for differently-abled persons: HC By www.thehindu.com Published On :: Sat, 09 May 2020 23:15:17 +0530 Asks govt. to examine possibility of earmarking exclusive funds for them Full Article Hyderabad
diff Facing difficulties due to non-availability of farm labour, say Amritsar farmers By www.newkerala.com Published On :: Sun, 05 Apr 2020 14:59:02 +0530 Full Article
diff How different is the PM CARES Fund from the PM’s National Relief Fund? By www.thehindu.com Published On :: Sun, 10 May 2020 01:23:32 +0530 Does not India already have a fund with similar objectives? Full Article National
diff Assam changes labour laws, but differs from BJP model By www.rediff.com Published On :: Sun, 10 May 2020 10:31:39 +0530 Unlike the other Bharatiya Janata Party-led governments, Assam has not proposed doing away with most labour laws for a certain number of years. Instead it has proposed introducing fixed-term employment to help both workers and industries, and seeks to take more firms out of the ambit of laws governing factories and contract workers. Full Article
diff Fast identification of mineral inclusions in diamond at GSECARS using synchrotron X-ray microtomography, radiography and diffraction By scripts.iucr.org Published On :: 2019-07-19 Mineral inclusions in natural diamond are widely studied for the insight that they provide into the geochemistry and dynamics of the Earth's interior. A major challenge in achieving thorough yet high rates of analysis of mineral inclusions in diamond derives from the micrometre-scale of most inclusions, often requiring synchrotron radiation sources for diffraction. Centering microinclusions for diffraction with a highly focused synchrotron beam cannot be achieved optically because of the very high index of refraction of diamond. A fast, high-throughput method for identification of micromineral inclusions in diamond has been developed at the GeoSoilEnviro Center for Advanced Radiation Sources (GSECARS), Advanced Photon Source, Argonne National Laboratory, USA. Diamonds and their inclusions are imaged using synchrotron 3D computed X-ray microtomography on beamline 13-BM-D of GSECARS. The location of every inclusion is then pinpointed onto the coordinate system of the six-circle goniometer of the single-crystal diffractometer on beamline 13-BM-C. Because the bending magnet branch 13-BM is divided and delivered into 13-BM-C and 13-BM-D stations simultaneously, numerous diamonds can be examined during coordinated runs. The fast, high-throughput capability of the methodology is demonstrated by collecting 3D diffraction data on 53 diamond inclusions from Juína, Brazil, within a total of about 72 h of beam time. Full Article text
diff Microsecond time-resolved X-ray diffraction for the investigation of fatigue behavior during ultrasonic fatigue loading By scripts.iucr.org Published On :: 2019-08-20 A new method based on time-resolved X-ray diffraction is proposed in order to measure the elastic strain and stress during ultrasonic fatigue loading experiments. Pure Cu was chosen as an example material for the experiments using a 20 kHz ultrasonic fatigue machine mounted on the six-circle diffractometer available at the DiffAbs beamline on the SOLEIL synchrotron facility in France. A two-dimensional hybrid pixel X-ray detector (XPAD3.2) was triggered by the strain gage signal in a synchronous data acquisition scheme (pump–probe-like). The method enables studying loading cycles with a period of 50 µs, achieving a temporal resolution of 1 µs. This allows a precise reconstruction of the diffraction patterns during the loading cycles. From the diffraction patterns, the position of the peaks, their shifts and their respective broadening can be deduced. The diffraction peak shift allows the elastic lattice strain to be estimated with a resolution of ∼10−5. Stress is calculated by the self-consistent scale-transition model through which the elastic response of the material is estimated. The amplitudes of the cyclic stresses range from 40 to 120 MPa and vary linearly with respect to the displacement applied by the ultrasonic machine. Moreover, the experimental results highlight an increase of the diffraction peak broadening with the number of applied cycles. Full Article text
diff Location of Cu2+ in CHA zeolite investigated by X-ray diffraction using the Rietveld/maximum entropy method By journals.iucr.org Published On :: Rietveld/MEM analysis applied to synchrotron powder X-ray diffraction data of dehydrated CHA zeolites with catalytically active Cu2+ reveals Cu2+ in both the six- and eight-membered rings in the CHA framework, providing the first complete structural model that accounts for all Cu2+. Density functional theory calculations are used to corroborate the experimental structure and to discuss the Cu2+ coordination in terms of the Al distribution in the framework. Full Article text
diff Diffuse scattering and partial disorder in complex structures By journals.iucr.org Published On :: This review discusses the state of the field of single-crystal diffuse scattering (SCDS), including detectors, data collection and the modelling techniques. High quality, three-dimensional volumes of SCDS data can now be collected at synchrotron light sources, allowing increasingly detailed and quantitative analyses to be undertaken. Full Article text
diff The first X-ray diffraction measurements on Mars By journals.iucr.org Published On :: The X-ray diffraction/X-ray fluorescence instrument CheMin on the Curiosity rover is a shoebox-sized device using transmission geometry and an energy-discriminating CCD detector. The instrument has returned the first X-ray diffraction data for soil and drilled samples from Mars outcrops, revealing a suite of primary basaltic minerals, amorphous components and varied hydrous alteration products including phyllosilicates. Full Article text
diff Capability of X-ray diffraction for the study of microstructure of metastable thin films By journals.iucr.org Published On :: PLEASE REDUCE TO 1-2 SENTENCES. The capability of X-ray diffraction for the microstructure investigations of metastable systems is illustrated on the example of thin films of titanium aluminium nitrides with high aluminium content, which are supersaturated and partially decomposed. In addition to the chemical composition, the surface mobility of the deposited species was employed as a factor influencing the microstructure of the thin films. It is shown how the micromechanical properties of the partially decomposed (Ti,Al)N thin films, which were deduced from the synchrotron diffraction experiments, are related to the thin film microstructure and to the decomposition mechanism. The prominent role of the crystallographic anisotropy of the macroscopic and microscopic lattice deformations in the understanding of the micromechanical properties is addressed. Full Article text
diff Precession electron diffraction – a topical review By journals.iucr.org Published On :: This topical review highlights progress made recently in the development and application of precession electron diffraction (PED) and its scanning variant for the determination of unknown crystal structures and the mapping of orientations at the nanoscale. Full Article text
diff Climate change: Cardiff study says ground-water could heat homes - BBC News By www.bbc.co.uk Published On :: Tue, 22 Oct 2019 07:00:00 GMT Climate change: Cardiff study says ground-water could heat homes BBC News Full Article
diff Scaling diffraction data in the DIALS software package: algorithms and new approaches for multi-crystal scaling By journals.iucr.org Published On :: A new scaling program is presented with new features to support multi-sweep workflows and analysis within the DIALS software package. Full Article text
diff Rubidium tetrafluoridobromate(III): redetermination of the crystal structure from single-crystal X-ray diffraction data By scripts.iucr.org Published On :: 2019-11-29 Single crystals of rubidium tetrafluoridobromate(III), RbBrF4, were grown by melting and recrystallizing RbBrF4 from its melt. This is the first determination of the crystal structure of RbBrF4 using single-crystal X-ray diffraction data. We confirmed that the structure contains square-planar [BrF4]− anions and rubidium cations that are coordinated by F atoms in a square-antiprismatic manner. The compound crystallizes in the KBrF4 structure type. Atomic coordinates and bond lengths and angles were determined with higher precision than in a previous report based on powder X-ray diffraction data [Ivlev et al. (2015). Z. Anorg. Allg. Chem. 641, 2593–2598]. Full Article text
diff Redetermination of the crystal structure of caesium tetrafluoridobromate(III) from single-crystal X-ray diffraction data By scripts.iucr.org Published On :: 2020-01-31 Caesium tetrafluoridobromate(III), CsBrF4, was crystallized in form of small blocks by melting and recrystallization. The crystal structure of CsBrF4 was redetermined from single-crystal X-ray diffraction data. In comparison with a previous study based on powder X-ray diffraction data [Ivlev et al. (2013). Z. Anorg. Allg. Chem. 639, 2846–2850], bond lengths and angles were determined with higher precision, and all atoms were refined with anisotropic displacement parameters. It was confirmed that the structure of CsBrF4 contains two square-planar [BrF4]− anions each with point group symmetry mmm, and a caesium cation (site symmetry mm2) that is coordinated by twelve fluorine atoms, forming an anticuboctahedron. CsBrF4 is isotypic with CsAuF4. Full Article text
diff A molybdenum tris(dithiolene) complex coordinates to three bound cobalt centers in three different ways By scripts.iucr.org Published On :: 2019-07-26 The synthesis and structural characterization of the molecular compound (μ3-benzene-1,2-dithiolato)hexacarbonylbis(μ3-1,1,1,4,4,4-hexafluorobut-2-ene-2,3-dithiolato)tricobaltmolybdenum, [Co3Mo(C4F6S2)2(C6H4S2)(CO)6] or Mo(tfd)2(bdt)(Co(CO)2)3 (tfd is 1,1,1,4,4,4-hexafluorobut-2-ene-2,3-dithiolate and bdt is benzene-1,2-dithiolate), are reported. The structure of the molecule contains the molybdenum tris(dithiolene) complex Mo(tfd)2(bdt) coordinated as a multidentate ligand to three cobalt dicarbonyl units. Each of the three cobalt centers is relatively close to molybdenum, with Co⋯Mo distances of 2.7224 (7), 2.8058 (7), and 2.6320 (6) Å. Additionally, each of the cobalt centers is bound via main-group donor atoms, but each one in a different way: the first cobalt atom is coordinated by two sulfur atoms from different dithiolenes (bdt and tfd). The second cobalt atom is coordinated by one sulfur from one tfd and two olefinic carbons from another tfd. The third cobalt is coordinated by one sulfur from bdt and two sulfurs from tfd. This is, to the best of our knowledge, the first structurally characterized example of a molybdenum (tris)dithiolene complex that coordinates to cobalt. The F atoms of two of the –CF3 groups were refined as disordered over two sets of sites with ratios of refined occupancies of 0.703 (7):0.297 (7) and 0.72 (2):0.28 (2). Full Article text
diff Six 1-aroyl-4-(4-methoxyphenyl)piperazines: similar molecular structures but different patterns of supramolecular assembly By scripts.iucr.org Published On :: 2019-07-26 Six new 1-aroyl-4-(4-methoxyphenyl)piperazines have been prepared, using coupling reactions between benzoic acids and N-(4-methoxyphenyl)piperazine. There are no significant hydrogen bonds in the structure of 1-benzoyl-4-(4-methoxyphenyl)piperazine, C18H20N2O2, (I). The molecules of 1-(2-fluorobenzoyl)-4-(4-methoxyphenyl)piperazine, C18H19FN2O2, (II), are linked by two C—H⋯O hydrogen bonds to form chains of rings, which are linked into sheets by an aromatic π–π stacking interaction. 1-(2-Chlorobenzoyl)-4-(4-methoxyphenyl)piperazine, C18H19ClN2O2, (III), 1-(2-bromobenzoyl)-4-(4-methoxyphenyl)piperazine, C18H19BrN2O2, (IV), and 1-(2-iodobenzoyl)-4-(4-methoxyphenyl)piperazine, C18H19IN2O2, (V), are isomorphous, but in (III) the aroyl ring is disordered over two sets of atomic sites having occupancies of 0.942 (2) and 0.058 (2). In each of (III)–(V), a combination of two C—H⋯π(arene) hydrogen bonds links the molecules into sheets. A single O—H⋯O hydrogen bond links the molecules of 1-(2-hydroxybenzoyl)-4-(4-methoxyphenyl)piperazine, C18H20N2O3, (VI), into simple chains. Comparisons are made with the structures of some related compounds. Full Article text
diff Different packing motifs mediated by weak interactions and polymorphism in the crystal structures of five 2-(benzylidene)benzosuberone derivatives By scripts.iucr.org Published On :: 2019-10-29 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. Full Article text
diff Crystal structure of a nickel compound comprising two nickel(II) complexes with different ligand environments: [Ni(tren)(H2O)2][Ni(H2O)6](SO4)2 By scripts.iucr.org Published On :: 2020-02-06 The title compound, diaqua[tris(2-aminoethyl)amine]nickel(II) hexaaquanickel(II) bis(sulfate), [Ni(C6H18N4)(H2O)2][Ni(H2O)6](SO4)2 or [Ni(tren)(H2O)2][Ni(H2O)6](SO4)2, consists of two octahedral nickel complexes within the same unit cell. These metal complexes are formed from the reaction of [Ni(H2O)6](SO4) and the ligand tris(2-aminoethyl)amine (tren). The crystals of the title compound are purple, different from those of the starting complex [Ni(H2O)6](SO4), which are turquoise. The reaction was performed both in a 1:1 and 1:2 metal–ligand molar ratio, always yielding the co-precipitation of the two types of crystals. The asymmetric unit of the title compound, which crystallizes in the space group Pnma, consists of two half NiII complexes and a sulfate counter-anion. The mononuclear cationic complex [Ni(tren)(H2O)2]2+ comprises an Ni ion, the tren ligand and two water molecules, while the mononuclear complex [Ni(H2O)6]2+ consists of another Ni ion surrounded by six coordinated water molecules. The [Ni(tren)(H2O)2] and [Ni(H2O)6] subunits are connected to the SO42− counter-anions through hydrogen bonding, thus consolidating the crystal structure. Full Article text
diff Syntheses and crystal structures of the one-dimensional coordination polymers formed by [Ni(cyclam)]2+ cations and 1,3-bis(3-carboxypropyl)tetramethyldisiloxane anions in different degrees of deprotonation By scripts.iucr.org Published On :: 2020-02-25 The asymmetric units of the title compounds, namely, catena-poly[[(1,4,8,11-tetraazacyclotetradecane-κ4N1,N4,N8,N11)nickel(II)]-μ-1,3-bis(3-carboxylatopropyl)tetramethyldisiloxane-κ2O:O'], [Ni(C10H24O5Si2)(C12H24N4)]n (I), and catena-poly[[[(1,4,8,11-tetraazacyclotetradecane-κ4N1,N4,N8,N11)nickel(II)]-μ-4-({[(3-carboxypropyl)dimethylsilyl]oxy}dimethylsilyl)butanoato-κ2O:O'] perchlorate], {[Ni(C10H25O5Si2)(C12H24N4)]ClO4}n (II), consist of one (in I) or two crystallographically non-equivalent (in II) centrosymmetric macrocyclic cations and one centrosymmetric dianion (in I) or two centrosymmetric monoanions (in II). In each compound, the metal ion is coordinated by the four secondary N atoms of the macrocyclic ligand, which adopts the most energetically stable trans-III conformation, and the mutually trans O atoms of the carboxylate in a slightly tetragonally distorted trans-NiN4O2 octahedral coordination geometry. The crystals of both types of compounds are composed of parallel polymeric chains of the macrocyclic cations linked by the anions of the acid running along the [101] and [110] directions in I and II, respectively. In I, each polymeric chain is linked to four neighbouring ones by hydrogen bonding between the NH groups of the macrocycle and the carboxylate O atoms, thus forming a three-dimensional supramolecular network. In II, each polymeric chain contacts with only two neighbours, forming hydrogen bonds between the partially protonated carboxylic groups of the bridging ligand. As a result, a lamellar structure is formed with the layers oriented parallel to the (1overline{1}1) plane. Full Article text
diff Redetermination of the crystal structure of R5Si4 (R = Pr, Nd) from single-crystal X-ray diffraction data By scripts.iucr.org Published On :: 2020-03-10 The crystal structures of praseodymium silicide (5/4), Pr5Si4, and neodymium silicide (5/4), Nd5Si4, were redetermined using high-quality single-crystal X-ray diffraction data. The previous structure reports of Pr5Si4 were only based on powder X-ray diffraction data [Smith et al. (1967). Acta Cryst. 22 940–943; Yang et al. (2002b). J. Alloys Compd. 339, 189–194; Yang et al., (2003). J. Alloys Compd. 263, 146–153]. On the other hand, the structure of Nd5Si4 has been determined from powder data [neutron; Cadogan et al., (2002). J. Phys. Condens. Matter, 14, 7191–7200] and X-ray [Smith et al. (1967). Acta Cryst. 22 940–943; Yang et al. (2002b). J. Alloys Compd. 339, 189–194; Yang et al., (2003). J. Alloys Compd. 263, 146–153] and single-crystal data with isotropic atomic displacement parameters [Roger et al., (2006). J. Alloys Compd. 415, 73–84]. In addition, the anisotropic atomic displacement parameters for all atomic sites have been determined for the first time. These compounds are confirmed to have the tetragonal Zr5Si4-type structure (space group: P41212), as reported previously (Smith et al., 1967). The structure is built up by distorted body-centered cubes consisting of Pr(Nd) atoms, which are linked to each other by edge-sharing to form a three-dimensional framework. This framework delimits zigzag channels in which the silicon dimers are situated. Full Article text
diff Different packing motifs in the crystal structures of three molecular salts containing the 2-amino-5-carboxyanilinium cation: C7H9N2O2+·Cl−, C7H9N2O2+·Br− and C7H9N2O2+·NO3−·H2O By scripts.iucr.org Published On :: 2020-03-13 The syntheses and crystal structures of three molecular salts of protonated 3,4-diaminobenzoic acid, viz. 2-amino-5-carboxyanilinium chloride, C7H9N2O2+·Cl−, (I), 2-amino-5-carboxyanilinium bromide, C7H9N2O2+·Br−, (II), and 2-amino-5-carboxyanilinium nitrate monohydrate, C7H9N2O2+·NO3−·H2O, (III), are described. The cation is protonated at the meta-N atom (with respect to the carboxy group) in each case. In the crystal of (I), carboxylic acid inversion dimers linked by pairwise O—H⋯O hydrogen bonds are seen and each N—H group forms a hydrogen bond to a chloride ion to result in (100) undulating layers of chloride ions bridged by the inversion dimers into a three-dimensional network. The extended structure of (II) features O—H⋯Br, N—H⋯Br and N—H⋯O hydrogen bonds: the last of these generates C(7) chains of cations. Overall, the packing in (II) features undulating (100) sheets of bromide ions alternating with the organic cations. Intermolecular interactions in the crystal of (III) include O—H⋯O, O—H⋯(O,O), N—H⋯O, N—H⋯N and O—H⋯N links. The cations are linked into (001) sheets, and the nitrate ions and water molecules form undulating chains. Taken together, alternating (001) slabs of organic cations plus anions/water molecules result. Hirshfeld surfaces and fingerprint plots were generated to give further insight into the intermolecular interactions in these structures. The crystal used for the data collection of (II) was twinned by rotation about [100] in reciprocal space in a 0.4896 (15):0.5104 (15) ratio. Full Article text
diff The crystal structures of Fe-bearing MgCO3 sp2- and sp3-carbonates at 98 GPa from single-crystal X-ray diffraction using synchrotron radiation By scripts.iucr.org Published On :: 2020-04-21 The crystal structure of MgCO3-II has long been discussed in the literature where DFT-based model calculations predict a pressure-induced transition of the carbon atom from the sp2 to the sp3 type of bonding. We have now determined the crystal structure of iron-bearing MgCO3-II based on single-crystal X-ray diffraction measurements using synchrotron radiation. We laser-heated a synthetic (Mg0.85Fe0.15)CO3 single crystal at 2500 K and 98 GPa and observed the formation of a monoclinic phase with composition (Mg2.53Fe0.47)C3O9 in the space group C2/m that contains tetrahedrally coordinated carbon, where CO44− tetrahedra are linked by corner-sharing oxygen atoms to form three-membered C3O96− ring anions. The crystal structure of (Mg0.85Fe0.15)CO3 (magnesium iron carbonate) at 98 GPa and 300 K is reported here as well. In comparison with previous structure-prediction calculations and powder X-ray diffraction data, our structural data provide reliable information from experiments regarding atomic positions, bond lengths, and bond angles. Full Article text
diff Equatorial aberration of powder diffraction data collected with an Si strip X-ray detector by a continuous-scan integration method By scripts.iucr.org Published On :: 2020-05-05 Exact and approximate mathematical formulas of equatorial aberration for powder diffraction data collected with an Si strip X-ray detector in continuous-scan integration mode are presented. An approximate formula is applied to treat the experimental data measured with a commercial powder diffractometer. Full Article text
diff Accurate high-resolution single-crystal diffraction data from a Pilatus3 X CdTe detector By scripts.iucr.org Published On :: 2020-04-23 Hybrid photon-counting detectors are widely established at third-generation synchrotron facilities and the specifications of the Pilatus3 X CdTe were quickly recognized as highly promising in charge-density investigations. This is mainly attributable to the detection efficiency in the high-energy X-ray regime, in combination with a dynamic range and noise level that should overcome the perpetual problem of detecting strong and weak data simultaneously. These benefits, however, come at the expense of a persistent problem for high diffracted beam flux, which is particularly problematic in single-crystal diffraction of materials with strong scattering power and sharp diffraction peaks. Here, an in-depth examination of data collected on an inorganic material, FeSb2, and an organic semiconductor, rubrene, revealed systematic differences in strong intensities for different incoming beam fluxes, and the implemented detector intensity corrections were found to be inadequate. Only significant beam attenuation for the collection of strong reflections was able to circumvent this systematic error. All data were collected on a bending-magnet beamline at a third-generation synchrotron radiation facility, so undulator and wiggler beamlines and fourth-generation synchrotrons will be even more prone to this error. On the other hand, the low background now allows for an accurate measurement of very weak intensities, and it is shown that it is possible to extract structure factors of exceptional quality using standard crystallographic software for data processing (SAINT-Plus, SADABS and SORTAV), although special attention has to be paid to the estimation of the background. This study resulted in electron-density models of substantially higher accuracy and precision compared with a previous investigation, thus for the first time fulfilling the promise of photon-counting detectors for very accurate structure factor measurements. Full Article text