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Sample records for crystallographically independent mol-ecules

  1. Crystal structure of 5-amino-5'-chloro-6-(4-chloro-benzo-yl)-8-nitro-2,3-di-hydro-1H-spiro-[imidazo[1,2-a]pyridine-7,3'-indolin]-2'-one including an unknown solvent mol-ecule.

    Science.gov (United States)

    Nagalakshmi, R A; Suresh, J; Sivakumar, S; Kumar, R Ranjith; Lakshman, P L Nilantha

    2014-09-01

    The asymmetric unit of the title compound, C21H15Cl2N5O4, contains two independent mol-ecules (A and B) having similar conformations. The amine (NH2) group forms an intra-molecular hydrogen bond with the benzoyl group, giving an S(6) ring motif in both mol-ecules. The central six-membered rings adopt sofa conformations and the imidazole rings are planar (r.m.s deviations = 0.0150 and 0.0166 Å). The pyridine and imidazole rings are inclined to one another by 3.54 (1) and 3.03 (1)° in mol-ecules A and B, respectively. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, forming chains along the a axis which enclose R 2 (2)(16) ring motifs. The rings are linked by weak N-H⋯O and C-H⋯O hydrogen bonds and C-H⋯π inter-actions forming sheets lying parallel to (001). A region of disordered electron density, most probably disordered solvent mol-ecules, occupying voids of ca 753 Å(3) for an electron count of 260, was treated using the SQUEEZE routine in PLATON [Spek (2009 ▶). Acta Cryst. D65, 148-155]. Their formula mass and unit-cell characteristics were not taken into account during refinement.

  2. Crystal structure of a 2:1 piroxicam-gentisic acid co-crystal featuring neutral and zwitterionic piroxicam mol-ecules.

    Science.gov (United States)

    Horstman, Elizabeth M; Bertke, Jeffery A; Woods, Toby J; Kenis, Paul J A

    2016-12-01

    A new 2:1 co-crystal of piroxicam and gentisic acid [systematic name: 4-hy-droxy-1,1-dioxo-N-(pyridin-2-yl)-2H-1λ(6),2-benzo-thia-zine-3-carboxamide-2-(4-oxido-1,1-dioxo-2H-1λ(6),2-benzo-thia-zine-3-amido)-pyridin-1-ium-2,5-di-hydroxy-benzoic acid, 2C15H13N3O4S·C7H6O4] has been synthesized using a microfluidic platform and initially identified using Raman spectroscopy. In the co-crystal, one piroxicam mol-ecule is in its neutral form and an intra-molecular O-H⋯O hydrogen bond is observed. The other piroxicam mol-ecule is zwitterionic (proton transfer from the OH group to the pyridine N atom) and two intra-molecular N-H⋯O hydrogen bonds occur. The gentisic acid mol-ecule shows whole-mol-ecule disorder over two sets of sites in a 0.809 (2):0.191 (2) ratio. In the crystal, extensive hydrogen bonding between the components forms layers propagating in the ab plane.

  3. Channels with ordered water and bipyridine mol-ecules in the porous coordination polymer {[Cu(SiF6)(C10H8N2)2]·2C10N2H8·5H2O} n.

    Science.gov (United States)

    Aubert, Emmanuel; Doudouh, Abdelatif; Peluso, Paola; Mamane, Victor

    2016-11-01

    The coordination polymer {[Cu(SiF6)(C10H8N2)2]·2C10H8N2·5H2O} n , systematic name: poly[[bis-(μ2-4,4'-bi-pyridine)(μ2-hexa-fluorido-silicato)copper(II)] 4,4'-bi-pyridine disolvate penta-hydrate], contains pores which are filled with water and 4,4'-bi-pyridine mol-ecules. As a result of the presence of these ordered species, the framework changes its symmetry from P4/mmm to P21/c. The 4,4'-bi-pyridine guest mol-ecules form chains inside the 6.5 × 6.9 Å pores parallel to [100] in which the mol-ecules inter-act through π-π stacking. Ordered water mol-ecules form infinite hydrogen-bonded chains inside a second pore system (1.6 × 5.3 Å free aperture) perpendicular to the 4,4'-bi-pyridine channels.

  4. Crystal structure of cis-bis-{4-phenyl-1-[(3R)-1,7,7-tri-methyl-2-oxobi-cyclo-[2.2.1]heptan-3-ylidene]thio-semicarbazidato-κ(3) O,N (1),S}cadmium(II) with an unknown solvent mol-ecule.

    Science.gov (United States)

    Nogueira, Vanessa Senna; Bresolin, Leandro; Näther, Christian; Jess, Inke; de Oliveira, Adriano Bof

    2015-12-01

    The reaction between the racemic mixture of the camphor-4-phenyl-thio-semicarbazone derivative and cadmium acetate dihydrate yielded the title compound, [Cd(C17H20N3OS)2]. The Cd(II) ion is six-coordinated in a distorted octa-hedral environment by two deprotonated thio-semicarbazone ligands acting as an O,N,S-donor in a tridentate chelating mode, forming five-membered chelate rings. In the crystal, the mol-ecules are connected via pairs of N-H⋯S and C-H⋯S inter-actions, building centrosymmetric dimers. One of the ligands is disordered in the campher unit over two sets of sites with site-occupancy factors of 0.7 and 0.3. The structure contains additional solvent mol-ecules, which are disordered and for which no reasonable split model was found. Therefore, the data were corrected for disordered solvent using the SQUEEZE routine [Spek (2015 ▸). Acta Cryst. C71, 9-18] in PLATON. Since the disordered solvents were removed by data processing, and the number of solvent entities was a suggestion only, they were not considered in the chemical formula and subsequent chemical or crystal information.

  5. Crystal structure of N-[(4-eth-oxy-phen-yl)carbamo-thio-yl]cyclo-hexa-ne-carboxamide.

    Science.gov (United States)

    Vimala, G; Haribabu, J; Srividya, S; Karvembu, R; SubbiahPandi, A

    2015-11-01

    The asymmetric unit of the title compound, C16H22N2O2S, contains two crystallographically independent mol-ecules (A and B). In mol-ecule A, the cyclo-hexane ring is disordered over two orientations [occupancy ratio 0.841 (10):0.159 (10)]. In each mol-ecule, the central carbonyl thio-urea unit is nearly planar (r.m.s. deviations for all non-H atoms of 0.034 Å in mol-ecule A and 0.094 Å in mol-ecule B). In both mol-ecules, the cyclo-hexane ring adopts a chair conformation. The mean plane of the cyclo-hexane ring makes dihedral angles of 35.8 (4) (mol-ecule A) and 20.7 (3)° (mol-ecule B) with that of the benzene ring. Each mol-ecule features an intra-molecular N-H⋯O hydrogen bond, which closes an S(6) ring motif. In the crystal, mol-ecules are linked via pairs of weak N-H⋯S inter-actions, forming inversion dimers with an R 2 (2)(8) ring motif for both mol-ecules. The crystal structure also features weak C-H⋯π ring inter-actions.

  6. Cluster Analysis of Time-Dependent Crystallographic Data: Direct Identification of Time-Independent Structural Intermediates

    Science.gov (United States)

    Kostov, Konstantin S.; Moffat, Keith

    2011-01-01

    The initial output of a time-resolved macromolecular crystallography experiment is a time-dependent series of difference electron density maps that displays the time-dependent changes in underlying structure as a reaction progresses. The goal is to interpret such data in terms of a small number of crystallographically refinable, time-independent structures, each associated with a reaction intermediate; to establish the pathways and rate coefficients by which these intermediates interconvert; and thereby to elucidate a chemical kinetic mechanism. One strategy toward achieving this goal is to use cluster analysis, a statistical method that groups objects based on their similarity. If the difference electron density at a particular voxel in the time-dependent difference electron density (TDED) maps is sensitive to the presence of one and only one intermediate, then its temporal evolution will exactly parallel the concentration profile of that intermediate with time. The rationale is therefore to cluster voxels with respect to the shapes of their TDEDs, so that each group or cluster of voxels corresponds to one structural intermediate. Clusters of voxels whose TDEDs reflect the presence of two or more specific intermediates can also be identified. From such groupings one can then infer the number of intermediates, obtain their time-independent difference density characteristics, and refine the structure of each intermediate. We review the principles of cluster analysis and clustering algorithms in a crystallographic context, and describe the application of the method to simulated and experimental time-resolved crystallographic data for the photocycle of photoactive yellow protein. PMID:21244840

  7. Crystal structure of 6,6,12,12-tetra-chloro-tri-cyclo-[8.2.0.0(4,7)]dodecane-5,11-dione.

    Science.gov (United States)

    Turan Akın, Esra; Hökelek, Tuncer

    2015-09-01

    The asymmetric unit of the title compound, C12H12Cl4O2, contains two crystallographically independent mol-ecules with almost identical conformations (r.m.s. overlay fit for the non-hydrogen atoms = 0.059 Å). In each mol-ecule, the central eight-membered ring has a distorted boat configuration, and two non-planar four-membered rings are fused on either side of the eight-membered ring. A weak C-H⋯O hydrogen bond links the two independent mol-ecules. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules into a two-dimensional network parallel to (001).

  8. N-(4-Meth-oxy-phen-yl)-6-methyl-2-phenyl-5-{[4-(tri-fluoro-meth-yl)anilino]meth-yl}pyrimidin-4-amine.

    Science.gov (United States)

    Cieplik, Jerzy; Pluta, Janusz; Bryndal, Iwona; Lis, Tadeusz

    2013-11-27

    The title compound, C26H23F3N4O, crystallizes with two symmetry-independent mol-ecules in the asymmetric unit, denoted A and B, which differ mainly in the rotation of the meth-oxy-phenyl ring. The -CF3 group of mol-ecule B is disordered by rotation, with the F atoms split over two sets of sites; the occupancy factor for the major component is 0.853 (4). The dihedral angles between the pyrimidine ring and the attached phenyl, meth-oxy-phenyl and tri-fluoro-methyl-phenyl rings are 8.1 (2), 37.5 (2) and 70.7 (2)°, respectively, in mol-ecule A, and 9.3 (2), 5.3 (2) and 79.7 (2)° in mol-ecule B. An intra-molecular N-H⋯N hydrogen bond occurs in each mol-ecule. In the crystal, two crystallographically independent mol-ecules associate into a dimer via a pair of N-H⋯N hydrogen bonds, with a resulting R 2 (2)(12) ring motif and π-π stacking inter-actions [centroid-centroid distance = 3.517 (4) Å] between the pyrimidine rings. For the A mol-ecules, there are inter-molecular C-H⋯O hydrogen bonds between an aryl C atom of meth-oxy-phenyl ring and a meth-oxy O atom of an adjacent mol-ecule. A similar inter-action is lacking in the B mol-ecules.

  9. (R)-Methyl {[(2-carb-oxy-bicyclo-[2.2.2]octan-1-yl)-ammonio]-methyl}-phos-phon-ate dichloro-methane 0.25-solvate.

    Science.gov (United States)

    Todorov, Petar; Calmes, Monique; Shivachev, Boris L; Nikolova, Rosica P

    2011-08-01

    The carb-oxy-lic acid mol-ecule of the title compound, C(11)H(20)NO(5)P·0.25CH(2)Cl(2), exists as a zwitterion with the H atom of the phospho-nate group being transferred to the imine N atom. In the asymmetric unit, there are two crystallographically independent acid mol-ecules adopting the same absolute configuration and differing slightly in their geometrical parameters. In each mol-ecule, the imino and carboxyl groups are connected via an intra-molecular N-H⋯O hydrogen bond. Inter-molecular O-H⋯O and N-H⋯O hydrogen bonds induce the formation of layers parallel to the ab plane. The dichloro-methane solvent mol-ecule, with a site occupancy of 0.5, is located between the layers.

  10. Bis{2-[(2,4,6-trimethyl-phen-yl)imino-methyl]pyrrol-1-ido}palladium(II).

    Science.gov (United States)

    Imhof, Wolfgang

    2013-02-01

    The title compound, [Pd(C(14)H(15)N(2))(2)], is a square-planar palladium complex composed of two deprotonated pyrrole-2-carbaldimine ligands coordinating a central Pd(II) atom. In the crystal, three crystallographically independent complex mol-ecules are observed, one of which is located in a general position, whereas the Pd(II) atoms of the other mol-ecules are situated on crystallographic inversion centers. The aromatic substituents at the imine N atoms in the three mol-ecules show dihedral angles of 87.6 (7)/83.64 (7), 74.3 (7) and 88.3 (7)° with respect to the corresponding PdN(4) plane.

  11. Test techniques for mol ecul ar biol 0gy 0f entomopathogenic fungi%虫生真菌的分子生物学检测技术

    Institute of Scientific and Technical Information of China (English)

    林华峰; 胡萃

    2001-01-01

    线粒体DNA探针、核糖体RNA编码DNA序列分析、随机扩增多态性DNA-聚合酶链式反应、基因组DNA探针和电泳核型分析,五类分子生物学技术在虫生真菌研究中已有应用.本文对此作了介绍,着重阐述了RAPD-PCR技术的特点及其使用此技术的研究成果.

  12. 4-(4-Chloro-phen-yl)-6-hydr-oxy-5-(2-thienyl-carbonyl)-6-(trifluoro-meth-yl)-3,4,5,6-tetra-hydro-pyrimidin-2(1H)-one monohydrate.

    Science.gov (United States)

    Mosslemin, Mohammad Hossein; Nateghi, Mohammad Reza; Sadoughi, Hesamaddin; Lamei, Asal

    2009-05-20

    The asymmetric unit of the title compound, C(16)H(12)ClF(3)N(2)O(3)S·H(2)O, contains two crystallographically independent organic mol-ecules and two water mol-ecules. The organic species are linked by an inter-molecular O-H⋯O hydrogen bond, while the water mol-ecules are connected to them through inter-molecular O-H⋯N hydrogen bonds. The thio-phene and phenyl rings are oriented at dihedral angles of 62.35 (4) in the first independent mol-ecule and 60.74 (5)° in the second, while the pyrimidine rings adopt twisted conformations in both molecules. Intra-molecular N-H⋯F inter-actions result in the formation of two five-membered rings having envelope conformations. In the crystal structure, further inter-molecular O-H⋯O and N-H⋯O hydrogen bonds link the mol-ecules into chains.

  13. Aqua{4,4',6,6'-tetrachloro-2,2'-[(2,2-dimethylpropane-1,3-diyl)bis(nitrilomethanylylidene)]diphenolato}zinc.

    Science.gov (United States)

    Kargar, Hadi; Kia, Reza; Abbasian, Saeideh; Tahir, Muhammad Nawaz

    2012-07-01

    The asymmetric unit of the title compound, [Zn(C(19)H(16)Cl(4)N(2)O(2))(H(2)O)], comprises two crystallographically independent mol-ecules. The geometry around the Zn(II) atoms is distorted trigonal-bipyramidal, supported by the N(2)O(2) donor atoms of the tetradentate Schiff base and a coordinating water mol-ecule. The dihedral angles between the benzene rings in the two mol-ecules are 34.10 (15) Å and 30.61 (15) Å. In the crystal, neighbouring independent mol-ecules are linked by pairs of O-H⋯O hydrogen bonds, forming dimers with R(2) (2)(6) ring motifs, and by O-H⋯Cl hydrogen bonds. There are short Cl⋯Cl [3.4728 (16), 3.4863 (16), and 3.388 (1) Å] contacts present, and mol-ecules are also linked by C-H⋯O and π-π [centroid-centroid distance = 3.671 (2) Å] inter-actions.

  14. N-(3,5-Dimethyl-phen-yl)-2-nitro-benzene-sulfonamide.

    Science.gov (United States)

    Chaithanya, U; Foro, Sabine; Gowda, B Thimme

    2012-10-01

    The asymmetric unit of the title compound, C(14)H(14)N(2)O(4)S, consists of two crystallographically independent mol-ecules. The mol-ecules are twisted at the S-N bonds with C-S-N-C torsion angles of 44.2 (3) and -49.3 (3)°. The dihedral angles between the benzene rings in the two mol-ecules are 71.53 (7) and 72.11 (7)°. The amide H atoms exhibit bifurcated intra- and inter-molecular hydrogen bonds; the intra-molecular N-H⋯O(N) hydrogen bonds generate S(7) motifs. In the crystal, the independent mol-ecules are separately connected through the inter-molecular N-H⋯O(S) hydrogen bonds, generating a C(4) motif and a helical chain along the b axis for one mol-ecule and an R(2) (2)(8) motif and an inversion dimer for the other. The crystal studied was a pseudo-merohedral twin with twin law (-100/0-10/001), the refined ratio of the twin domains being 0.7876 (12):0.2124 (12).

  15. Methyl-phospho-nic acid, CH3PO(OH)2.

    Science.gov (United States)

    Reuter, Hans; Reichelt, Martin

    2014-03-01

    The asymmetric unit of the title compound, CH5O3P, contains two independent mol-ecules with nearly identical bond lengths and angles. In the crystal, each of the mol-ecules acts as acceptor (P=O) and donor (P-OH) of four hydrogen bonds to three adjacent mol-ecules, resulting in the formation of two different bilayers (one for each mol-ecule) stacked perpendicular to the a axis in the crystal.

  16. Crystallographic Information Resources

    Science.gov (United States)

    Glasser, Leslie

    2016-01-01

    Crystallographic information provides the fundamental basis for understanding the properties and behavior of materials. This data, such as chemical composition, unit cell dimensions, space group, and atomic positions, derives from the primary literature--that is, from published experimental measurement or theoretical calculation. Although the…

  17. Crystal structure of glycidamide: the mutagenic and genotoxic metabolite of acryl-amide.

    Science.gov (United States)

    Hemgesberg, Melanie N; Bonck, Thorsten; Merz, Karl-Heinz; Sun, Yu; Schrenk, Dieter

    2016-08-01

    The title compound, glycidamide (systematic name: oxirane-2-carboxamide), C3H5NO2, is the mutagenic and genotoxic metabolite of acryl-amide, a food contaminant and industrial chemical that has been classified as being probably carcinogenic to humans. Synthesized via the reaction of acrylo-nitrile and hydrogen peroxide, it crystallizes with both enanti-omers occurring as two crystallographically independent mol-ecules (A and B) in the asymmetric unit. They have similar conformations with an r.m.s. deviation of 0.0809 Å for mol-ecule B inverted on mol-ecule A. In the crystal, mol-ecules are linked by N-H⋯O hydrogen bonds, which lead to the formation of β-sheet structures enclosing R 2 (2)(8) and R 4 (2)(8) loops. The β-sheets are linked by weaker C-H⋯O hydrogen bonds, forming a supra-molecular three-dimensional structure.

  18. Macromolecular crystallographic estructure refinement

    Directory of Open Access Journals (Sweden)

    Afonine, Pavel V.

    2015-04-01

    Full Text Available Model refinement is a key step in crystallographic structure determination that ensures final atomic structure of macromolecule represents measured diffraction data as good as possible. Several decades have been put into developing methods and computational tools to streamline this step. In this manuscript we provide a brief overview of major milestones of crystallographic computing and methods development pertinent to structure refinement.El refinamiento es un paso clave en el proceso de determinación de una estructura cristalográfica al garantizar que la estructura atómica de la macromolécula final represente de la mejor manera posible los datos de difracción. Han hecho falta varias décadas para poder desarrollar nuevos métodos y herramientas computacionales dirigidas a dinamizar esta etapa. En este artículo ofrecemos un breve resumen de los principales hitos en la computación cristalográfica y de los nuevos métodos relevantes para el refinamiento de estructuras.

  19. Crystal structures of 4-meth-oxy-benzoic acid-1,3-bis-(pyridin-4-yl)propane (2/1) and biphenyl-4,4'-di-carb-oxy-lic acid-4-meth-oxy-pyridine (1/2).

    Science.gov (United States)

    Gotoh, Kazuma; Ishida, Hiroyuki

    2017-07-01

    The crystal structures of two hydrogen-bonded compounds, namely 4-meth-oxy-benzoic acid-1,3-bis-(pyridin-4-yl)propane (2/1), C13H14.59N2·C8H7.67O3·C8H7.74O3, (I), and biphenyl-4,4'-di-carb-oxy-lic acid-4-meth-oxy-pyridine (1/2), C14H9.43O4·C6H7.32NO·C6H7.25NO, (II), have been determined at 93 K. In (I), the asymmetric unit consists of two crystallographically independent 4-meth-oxy-benzoic acid mol-ecules and one 1,3-bis-(pyridin-4-yl)propane mol-ecule. The asymmetric unit of (II) comprises one biphenyl-4,4'-di-carb-oxy-lic acid mol-ecule and two independent 4-meth-oxy-pyridine mol-ecules. In each crystal, the acid and base mol-ecules are linked by short O-H⋯N/N-H⋯O hydrogen bonds, in which H atoms are disordered over the acid O-atom and base N-atom sites, forming a linear hydrogen-bonded 2:1 or 1:2 unit of the acid and the base. The 2:1 units of (I) are linked via C-H⋯π, π-π and C-H⋯O inter-actions into a tape structure along [101], while the 1:2 units of (II) form a double-chain structure along [-101] through π-π and C-H⋯O inter-actions.

  20. Crystal structures of hydrogen-bonded co-crystals as liquid crystal precursors: 4-(n-pent-yloxy)benzoic acid-(E)-1,2-bis-(pyridin-4-yl)ethene (2/1) and 4-(n-hex-yloxy)benzoic acid-(E)-1,2-bis-(pyridin-4-yl)ethene (2/1).

    Science.gov (United States)

    Tabuchi, Yohei; Gotoh, Kazuma; Ishida, Hiroyuki

    2016-12-01

    The crystal structures of title hydrogen-bonded co-crystals, 2C12H16O3·C12H10N2, (I), and 2C13H18O3·C12H10N2, (II), have been determined at 93 K. In (I), the asymmetric unit consists of one 4-(n-pent-yloxy)benzoic acid mol-ecule and one half-mol-ecule of (E)-1,2-bis-(pyridin-4-yl)ethene, which lies about an inversion centre. The asymmetric unit of (II) comprises two crystallographically independent 4-(n-hex-yloxy)benzoic acid mol-ecules and one 1,2-bis-(pyridin-4-yl)ethene mol-ecule. In each crystal, the acid and base components are linked by O-H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit of the acid and the base. The 2:1 units are linked via C-H⋯π and π-π inter-actions [centroid-centroid distances of 3.661 (2) and 3.909 (2) Å for (I), and 3.546 (2)-3.725 (4) Å for (II)], forming column structures. In (II), the base mol-ecule is orientationally disordered over two sets of sites approximately around the N⋯N mol-ecular axis, with an occupancy ratio of 0.647 (4):0.353 (4), and the average structure of the 2:1 unit adopts nearly pseudo-C2 symmetry. Both compounds show liquid-crystal behaviour.

  1. Phaser crystallographic software.

    Science.gov (United States)

    McCoy, Airlie J; Grosse-Kunstleve, Ralf W; Adams, Paul D; Winn, Martyn D; Storoni, Laurent C; Read, Randy J

    2007-08-01

    Phaser is a program for phasing macromolecular crystal structures by both molecular replacement and experimental phasing methods. The novel phasing algorithms implemented in Phaser have been developed using maximum likelihood and multivariate statistics. For molecular replacement, the new algorithms have proved to be significantly better than traditional methods in discriminating correct solutions from noise, and for single-wavelength anomalous dispersion experimental phasing, the new algorithms, which account for correlations between F(+) and F(-), give better phases (lower mean phase error with respect to the phases given by the refined structure) than those that use mean F and anomalous differences DeltaF. One of the design concepts of Phaser was that it be capable of a high degree of automation. To this end, Phaser (written in C++) can be called directly from Python, although it can also be called using traditional CCP4 keyword-style input. Phaser is a platform for future development of improved phasing methods and their release, including source code, to the crystallographic community.

  2. Crystal structures of four co-crystals of (E)-1,2-di(pyridin-4-yl)ethene with 4-alk-oxy-benzoic acids: 4-meth-oxy-benzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1), 4-eth-oxy-benzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1), 4-n-propoxybenzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1) and 4-n-but-oxy-benzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1).

    Science.gov (United States)

    Tabuchi, Yohei; Gotoh, Kazuma; Ishida, Hiroyuki

    2016-11-01

    The crystal structures of four hydrogen-bonded co-crystals of 4-alk-oxy-benzoic acid-(E)-1,2-di(pyridin-4-yl)ethene (2/1), namely, 2C8H8O3·C12H10N2, (I), 2C9H10O3·C12H10N2, (II), 2C10H12O3·C12H10N2, (III) and 2C11H14O3·C12H10N2, (IV), have been determined at 93 K. In compounds (I) and (IV), the asymmetric units are each composed of one 4-alk-oxy-benzoic acid mol-ecule and one half-mol-ecule of (E)-1,2-di(pyridin-4-yl)ethene, which lies on an inversion centre. The asymmetric unit of (II) consists of two crystallographically independent 4-eth-oxy-benzoic acid mol-ecules and one 1,2-di(pyridin-4-yl)ethene mol-ecule. Compound (III) crystallizes in a non-centrosymmetric space group (Pc) and the asymmetric unit comprises four 4-n-propoxybenzoic acid mol-ecules and two (E)-1,2-di(pyridin-4-yl)ethane mol-ecules. In each crystal, the acid and base components are linked by O-H⋯N hydrogen bonds, forming a linear hydrogen-bonded 2:1 unit of the acid and the base. In (I), (II) and (III), inter-molecular C-H⋯O inter-actions are observed. The 2:1 units of (I) and (II) are linked via C-H⋯O hydrogen bonds, forming tape structures. In (III), the C-H⋯O hydrogen bonds, except for those formed in the units, link the two crystallographically independent 2:1 units. In (IV), no C-H⋯O inter-actions are observed, but π-π and C-H⋯π inter-actions link the units into a column structure.

  3. Crystal structure of cis-diamminebis(nitrito-κN)platinum(II).

    Science.gov (United States)

    Kahlenberg, Volker; Gelbrich, Thomas; Tessadri, Richard; Klauser, Frederik

    2015-04-01

    Single crystals of cis-[Pt(NO2)2(NH3)2], were obtained by means of hyper-saturation directly out of a plating electrolyte. The square-planar coordination environment of the divalent Pt(II) atom is formed by four N atoms belonging to two ammine and two monodentate nitrite ligands. The ligands adopt a cis configuration. The crystal structure contains stacks of close-packed mol-ecules which run parallel to [001]. There are nine crystallographically independent inter-molecular N-H⋯O hydrogen bonds, resulting in a hydrogen-bonded hxl-type framework in which each mol-ecule serves as an eight-connected node. Four of the nine distinct hydrogen bonds connect complexes which belong to the same close-packed column parallel to [001]. In contrast to the previously reported crystal structure of the trans isomer, the title structure does not display intra-molecular hydrogen bonding.

  4. Poly[[μ-aqua-aqua-[μ(4)-ethyl (dichloro-methyl-ene)diphospho-nato]sesqui-calcium(II)] acetone hemisolvate 4.5-hydrate].

    Science.gov (United States)

    Jokiniemi, Jonna; Peräniemi, Sirpa; Vepsäläinen, Jouko; Ahlgrén, Markku

    2009-03-25

    The title compound, {[Ca(1.5)(C(3)H(5)Cl(2)O(6)P(2))(H(2)O)(2)]·0.5CH(3)COCH(3)·4.5H(2)O}(n), has a two-dimensional polymeric structure. The asymmetric unit contains two crystallographically independent Ca(2+) cations connected by a chelating and bridging ethyl (dichloro-methyl-ene)diphos-pho-n-ate(3(-)) ligand and an aqua ligand. One of the Ca atoms, lying on a centre of symmetry, has a slightly distorted octa-hedral geometry, while the other Ca atom is seven-coordinated in a distorted monocapped trigonal-prismatic geometry. The polymeric layers are further connected by extensive O-H⋯O hydrogen bonding into a three-dimensional supra-molecular network. The acetone solvent mol-ecule and one uncoordin-ated water mol-ecule are located on twofold rotation axes.

  5. Crystallographic topology and its applications

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, C.K.; Burnett, M.N. [Oak Ridge National Lab., TN (United States); Dunbar, W.D. [Simon`s Rock Coll., Great Barrington, MA (United States). Div. of Natural Sciences and Mathematics

    1996-10-01

    Geometric topology and structural crystallography concepts are combined to define a new area we call Structural Crystallographic Topology, which may be of interest to both crystallographers and mathematicians. In this paper, we represent crystallographic symmetry groups by orbifolds and crystal structures by Morse - functions. The Morse function uses mildly overlapping Gaussian thermal-motion probability density functions centered on atomic sites to form a critical net with peak, pass, pale, and pit critical points joined into a graph by density gradient-flow separatrices. Critical net crystal structure drawings can be made with the ORTEP-III graphics pro- An orbifold consists of an underlying topological space with an embedded singular set that represents the Wyckoff sites of the crystallographic group. An orbifold for a point group, plane group, or space group is derived by gluing together equivalent edges or faces of a crystallographic asymmetric unit. The critical-net-on-orbifold model incorporates the classical invariant lattice complexes of crystallography and allows concise quotient-space topological illustrations to be drawn without the repetition that is characteristic of normal crystal structure drawings.

  6. CIF (Crystallographic Information File): A Standard for Crystallographic Data Interchange

    Science.gov (United States)

    Brown, I. D.

    1996-01-01

    The Crystallographic Information File (CIF) uses the self-defining STAR file structure. This requires the creation of a dictionary of data names and definitions. A basic dictionary of terms needed to describe the crystal structures of small molecules was approved in 1991 and is currently used for the submission of papers to Acta Crystallographica C. A number of extensions to this dictionary are in preparation. By storing the dictionary itself as a STAR file, the definitions and relationships in the CIF dictionary become computer interpretable. This offers many possibilities for the automatic handling of crystallographic information. PMID:27805170

  7. The birth of the European Crystallographic Committee (ECC) and of the European Crystallographic Meetings (ECMs)

    Science.gov (United States)

    Authier, A.

    2010-01-01

    This article describes the circumstances of the establishment of the European Crystallographic Committee, now the European Crystallographic Association, a regional associate of the IUCr, and of the European Crystallographic Meetings.

  8. N-(4-Methyl-benzo-yl)-2-nitro-benzene-sulfonamide.

    Science.gov (United States)

    Suchetan, P A; Foro, Sabine; Gowda, B Thimme

    2012-03-01

    The asymmetric unit of the title compound, C(14)H(12)N(2)O(5)S, contains two independent mol-ecules. The dihedral angles between the aromatic rings are 82.03 (9) and 79.47 (8)° in the two independent mol-ecules. In the crystal, the two mol-ecules in the asymmetric unit are linked into dimers via pairs of N-H⋯O(S) hydrogen bonds to generate C(4) chains.

  9. The Crystallographic Information File (CIF

    Directory of Open Access Journals (Sweden)

    I D Brown

    2006-11-01

    Full Text Available The Crystallographic Information File (CIF, owned by the International Union of Crystallography, is a file structure based on tag-value ASCII pairs with tags defined in machine-readable dictionaries. The crystallographic community publishes and archives large quantities of numeric information generated by crystal structure determinations, and CIF's acceptance was assured by its adoption as the submission format for Acta Crystallographica and by the obvious needs of the community. CIF's strength lies in its dictionaries, which define most of the concepts of crystallography; its weakness is the difficulty of writing software that exploits its full potential.

  10. Triboluminescence dominated by crystallographic orientation

    Science.gov (United States)

    Wang, Kuifang; Ma, Liran; Xu, Xuefeng; Wen, Shizhu; Luo, Jianbin

    2016-05-01

    Triboluminescence (TL) is an optical phenomenon that has a long and varied history with broad applications, such as damage detection, X-ray source, and mass health monitoring sensor. So far, the properties and mechanisms of TL remain not completely understood. The TL properties emitted during the sliding contact between Al2O3 and SiO2 surfaces were studied along different crystallographic orientations. In this study, the TL intensity of Al2O3 was significantly enhanced as Al2O3 surface was along a particular crystallographic orientation, which is an unconventional phenomenon. TL enhancement of Al2O3 was not affected by air atmosphere and atomic stocking mode of Al2O3. The enhancement mechanism of Al2O3 may be influenced by the surface state of Al2O3. This work provides a new method to control the intensity of TL and novel ideas to elucidate the TL mechanism.

  11. Crystallographic properties of fertilizer compounds

    Energy Technology Data Exchange (ETDEWEB)

    Frazier, A.W.; Dillard, E.F.; Thrasher, R.D.; Waerstad, K.R.; Hunter, S.R.; Kohler, J.J.; Scheib, R.M.

    1991-02-01

    This bulletin is a compilation of crystallographic data collected at NFERC on 450 fertilizer-related compounds. In TVA's fertilizer R and D program, petrographic examination, XRD, and infrared spectroscopy are combined with conventional chemical analysis methods in identifying the individual compounds that occur in fertilizer materials. This handbook brings together the results of these characterization studies and supplemental crystallographic data from the literature. It is in one-compound-per-page, loose-leaf format, ordered alphabetically by IUPAC name. Indexes provided include IUPAC name, formula, group, alternate formula, synonyms, x-ray data, optical data. Tables are given for solids, compounds in commercial MAP and DAP, and matrix materials in phosphate rock.

  12. 3-Acetyl-1-(4-methyl-phen-yl)thio-urea.

    Science.gov (United States)

    Gowda, B Thimme; Foro, Sabine; Kumar, Sharatha

    2012-07-01

    The asymmetric unit of the title compound, C(10)H(12)N(2)OS, contains two independent mol-ecules. In both mol-ecules, the conformations of the two N-H bonds are anti to each other. Furthermore, the conformations of the amide C=S bonds and the C=O bonds are anti to each other. The dihedral angles between the benzene ring and the side chain are 52.8 (1) and 68.0 (1)° in the two independent mol-ecules. An intra-molecular N-H⋯O hydrogen bond occurs in both independent mol-ecules. In the crystal, mol-ecules are linked into infinite chains along the a axis through a series of N-H⋯O and N-H⋯S hydrogen bonds.

  13. Internet Based Open Access Crystallographic Databases

    Science.gov (United States)

    Upreti, Girish; Seipel, Bjoern; Harvey, Morgan; Garrick, Will; Moeck, Peter

    2006-05-01

    Two freely accessible crystallographic databases are discussed: the Crystallographic Open Database (COD, http://crystallography.net) which contains over 37,000 crystal structures, and the Nano-Crystallography Database (NCD, http://nanocrystallography.research.pdx.edu) which we recently started to support image-based nanocrystallography and (nano) materials science education. Both databases collect crystallographic relevant information in a standardized format; the Crystallographic Information File (CIF). CIF is the standard file format adopted by the International Union of Crystallography (http://iucr.org) for the archiving and distribution of crystallographic information. A subset of the COD, the Predicted Crystallographic Online Database, allows for 3D structural displays of structural polyhedra and wireframes of approximately 2,600 entries. Since electron microscopist are interested in simple, yet technologically important materials, the crystallographic information for those materials will be included in our database. At our NCD site, entries in the COD and the NCD can be visualized in three dimensions (3D) along with (2D) lattice fringe fingerprints plots. The latter supports the identification of unknown nanocrystal phases from high-resolution transmission electron microscopy (HRTEM) images. Morphological crystal information from the database ``Bestimmungstabellen f"ur Kristalle/ ???????????? ??????????,'' (A.K. Boldyrew and W.W. Doliwo-Dobrowolsky, Zentrales Wissenschaftlichers Institute der Geologie und Sch"urfung, Leningrad/ Moscow, 1937/1939) will also be included in the NCD to support image-based nanocrystallography in 3D.

  14. Bis(2-hydroxy-benzaldehyde oxime) O,O'-butane-1,4-diyldicarbonyl ether.

    Science.gov (United States)

    Etemadi, Bijan; Kia, Reza; Sharghi, Hashem; Hosseini Sarvari, Mona

    2009-05-20

    The mol-ecule of the title compound, C(20)H(20)N(2)O(6), lies across a crystallographic inversion centre, the asymmetric unit comprising one half-mol-ecule. An intra-molecular O-H⋯N hydrogen bond generates a six-membered ring, producing an S(6) ring motif. Pairs of inter-molecular C-H⋯O hydrogen bonds link neighbouring mol-ecules into a layer with R(2) (2)(38) ring motif. The crystal structure is further stabilized by the inter-molecular C-H⋯π inter-actions.

  15. The New NRL Crystallographic Database

    Science.gov (United States)

    Mehl, Michael; Curtarolo, Stefano; Hicks, David; Toher, Cormac; Levy, Ohad; Hart, Gus

    For many years the Naval Research Laboratory maintained an online graphical database of crystal structures for a wide variety of materials. This database has now been redesigned, updated and integrated with the AFLOW framework for high throughput computational materials discovery (http://materials.duke.edu/aflow.html). For each structure we provide an image showing the atomic positions; the primitive vectors of the lattice and the basis vectors of every atom in the unit cell; the space group and Wyckoff positions; Pearson symbols; common names; and Strukturbericht designations, where available. References for each structure are provided, as well as a Crystallographic Information File (CIF). The database currently includes almost 300 entries and will be continuously updated and expanded. It enables easy search of the various structures based on their underlying symmetries, either by Bravais lattice, Pearson symbol, Strukturbericht designation or commonly used prototypes. The talk will describe the features of the database, and highlight its utility for high throughput computational materials design. Work at NRL is funded by a Contract with the Duke University Department of Mechanical Engineering.

  16. Defining the Crystallographic Fingerprint of Extraterrestrial Treasures

    Science.gov (United States)

    Forman, L. V.; Bland, P. A.; Timms, N. E.; Daly, L.; Benedix, G. K.; Trimby, P. W.

    2016-08-01

    An approach to determine the crystallographic fingerprint of chondritic matrix grains, which is complimentary to the geochemical signature commonly identified to constrain some aspects of the petrogenesis of a sample.

  17. N-(2,3-Dimethyl-phen-yl)-2-nitro-benzene-sulfonamide.

    Science.gov (United States)

    Chaithanya, U; Foro, Sabine; Gowda, B Thimme

    2012-11-01

    There are two independent mol-ecules in the asymmetric unit of the title compound, C(14)H(14)N(2)O(4)S. The N-H bonds are syn to the ortho-nitro groups in the sulfonyl benzene rings and anti to the methyl groups in the aniline benzene rings. The mol-ecules are twisted at the S-N bonds with torsion angles of -60.4 (3) and 58.8 (3)° in the two mol-ecules. The dihedral angles between the planes of the sulfonyl and the anilino benzene rings are 53.67 (8) and 56.99 (9)°. The amide H atoms of both mol-ecules are involved in an intra-molecular hydrogen bond, generating an S(7) motif. In the crystal, pairs of N-H⋯O(S) hydrogen bonds link like mol-ecules into inversion dimers.

  18. Nexus, crystallographic computing all around the world.

    Science.gov (United States)

    Cranswick, Lachlan Michael David; Bisson, William; Cockcroft, Jeremy Karl

    2008-01-01

    Crystallographic Nexus CD-ROMs, containing a range of free crystallographic software for single-crystal and powder diffraction available on the Internet, have been distributed on request since 1996. The free CD is made in the form of a ;virtual Internet' with the main intent of benefiting crystallographers with inadequate Internet access. The IUCr funds an annual/biennial update which is distributed to known previous recipients. Feedback from current recipients indicates the CD is still useful. The most current IUCr-funded CD is being produced by the CCP14 project at University College London and The Royal Institution UK for distribution to the ECM 2007 and AsCA 2007 conferences.

  19. Non-Crystallographic Symmetry in Packing Spaces

    Directory of Open Access Journals (Sweden)

    Valery G. Rau

    2013-01-01

    Full Text Available In the following, isomorphism of an arbitrary finite group of symmetry, non-crystallographic symmetry (quaternion groups, Pauli matrices groups, and other abstract subgroups, in addition to the permutation group, are considered. Application of finite groups of permutations to the packing space determines space tilings by policubes (polyominoes and forms a structure. Such an approach establishes the computer design of abstract groups of symmetry. Every finite discrete model of the real structure is an element of symmetry groups, including non-crystallographic ones. The set packing spaces of the same order N characterizes discrete deformation transformations of the structure.

  20. Bis(dimethyl-malonato-κO,O')bis-[4-(4-pyridylamino-κN)pyridinium]nickel(II) hexa-hydrate.

    Science.gov (United States)

    Farnum, Gregory A; Laduca, Robert L

    2008-11-22

    In the title compound, [Ni(C(5)H(6)O(4))(2)(C(10)H(10)N(3))(2)]·6H(2)O, divalent nickel ions situated on the crystallographic twofold axis are octa-hedrally coordinated by four O atoms from two dimethyl-malonate ligands in a 1,3-chelating mode and two N atoms from two protonated monodentate 4,4'-dipyridylamine mol-ecules. The mol-ecules link into chains via N-H⋯O hydrogen bonding mediated by protonated pyridyl groups. The chains form layer patterns via π-π stacking [centroid-centroid distance = 3.777 (2) Å] . Water mol-ecule hexa-mers are generated from the unligated water mol-ecules (three per asymmetric unit) by inversion centers at Wyckoff position d. These clusters are situated between the pseudolayers, providing hydrogen-bonding pathways that build up the three-dimensional structure.

  1. Poly[[hexa-aqua-sesqui(μ-benzene-1,2,4,5-tetra-carboxyl-ato)dicopper(II)disodium] monohydrate].

    Science.gov (United States)

    Camara, Magatte; Keita, Mohamed Fadel; Cisse, Cherif Cheikh Samsidine; Daiguebonne, Carole; Guillou, Olivier

    2014-08-01

    In the title compound, {[Cu2Na2(C10H2O8)1.5(H2O)6]·H2O} n , the Cu(2+) ion is hexa-coordinated by five O atoms from benzene-1,2,4,5-tetra-carboxyl-ate (btec(4-)) ligands and one water mol-ecule. The Na(+) ion is also hexa-coordinated, by four O atoms from btec(4-) ligands and two water mol-ecules. One of the two btec(4-) mol-ecules sits on a crystallographic inversion centre. CuO6 and NaO6 octa-hedra are connected, forming bi-dimensional layers. These layers, which extend parallel to the ac plane, are further inter-connected by μ10- or μ11-bridging btec(4-) ligands and by O-H⋯O hydrogen bonds, involving both btec(4-) ligands and water mol-ecules, forming a three-dimensional network.

  2. Crystal structure of bis-{4-bromo-2-[(carb-amim-id-amido-imino)-meth-yl]phenolato-κ(3) N,N',O}cobalt(III) nitrate di-methyl-formamide monosolvate.

    Science.gov (United States)

    Buvaylo, Elena A; Kasyanova, Katerina A; Vassilyeva, Olga Yu; Skelton, Brian W

    2016-07-01

    The title compound, [Co(C8H8BrN4O)2]NO3·C3H7NO, is formed of discrete [CoL 2](+) cations, nitrate anions and di-methyl-formamide (DMF) mol-ecules of crystallization. The cation has no crystallographically imposed symmetry. The ligand mol-ecules are deprotonated at the phenol O atom and octa-hedrally coordinate the Co(III) atoms through the azomethine N and phenolate O atoms in a mer configuration. The deprotonated ligand mol-ecules adopt an almost planar conformation. In the crystal lattice, the cations are arranged in layers in the ab plane divided by the nitrate anions and solvent mol-ecules. No π-π stacking is observed. All of the amine H atoms are involved in hydrogen bonding to nitrate, DMF or ligand O atoms or to one of the Br atoms, forming two-dimensional networks parallel to (100).

  3. N-(4-Chloro-3-methyl-phen-yl)succinamic acid.

    Science.gov (United States)

    Chaithanya, U; Foro, Sabine; Gowda, B Thimme

    2012-07-01

    The title compound, C(11)H(12)ClNO(3), crystallizes with two independent mol-ecules in the asymmetric unit in which the dihedral angles between the benzene ring and the amide group are 55.0 (2) and 28.2 (3)°. The two independent mol-ecules are linked by an N-H⋯O hydrogen bond. In the crystal, mol-ecules form inversion dimers via pairs of O-H⋯O hydrogen bonds. These dimers are linked into sheets parallel to (11-3) via N-H⋯O hydrogen bonds.

  4. Quantum crystallographic charge density of urea

    Directory of Open Access Journals (Sweden)

    Michael E. Wall

    2016-07-01

    Full Text Available Standard X-ray crystallography methods use free-atom models to calculate mean unit-cell charge densities. Real molecules, however, have shared charge that is not captured accurately using free-atom models. To address this limitation, a charge density model of crystalline urea was calculated using high-level quantum theory and was refined against publicly available ultra-high-resolution experimental Bragg data, including the effects of atomic displacement parameters. The resulting quantum crystallographic model was compared with models obtained using spherical atom or multipole methods. Despite using only the same number of free parameters as the spherical atom model, the agreement of the quantum model with the data is comparable to the multipole model. The static, theoretical crystalline charge density of the quantum model is distinct from the multipole model, indicating the quantum model provides substantially new information. Hydrogen thermal ellipsoids in the quantum model were very similar to those obtained using neutron crystallography, indicating that quantum crystallography can increase the accuracy of the X-ray crystallographic atomic displacement parameters. The results demonstrate the feasibility and benefits of integrating fully periodic quantum charge density calculations into ultra-high-resolution X-ray crystallographic model building and refinement.

  5. Crystallographic theory of the martensitic transformation

    Directory of Open Access Journals (Sweden)

    Edwar A. Torres-López

    2014-08-01

    Full Text Available The martensitic transformation is one of the most researched topics in the materials science during the 20th century. The second half of this century was mainly remembered by the development of several theories related with the kinetics of phase transformation, the mechanisms involved in the nucleation phenomenon, and the way as the crystallographic change is produced. In this paper are described the fundamental concepts that are defined in the crystallographic framework of the martensitic transformation. The study is focused on the application of the most outstanding crystallographic models: the Bain; the Wechsler, Lieberman & Read; and the Bowles & Mackenzie. The topic is presented based upon the particular features of the martensitic transformation, such as its non-diffusional character, type of interface between parent (austenite and product (martensite phases, the formation of substructural defects, and the shape change; all of these features are mathematically described by equations aimed to predict how the transformation will take place rather than to explain the actual movement of the atoms within the structure. This mathematical development is known as the Phenomenological Theory of Martensite Crystallography (PTMC.

  6. A preliminary neutron crystallographic study of thaumatin

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, Susana C. M. [ILL-EMBL Deuteration Laboratory, Partnership for Structural Biology, 6 Rue Jules Horowitz, 38042 Grenoble (France); Institut Laue Langevin, 6 Rue Jules Horowitz, 38042 Grenoble (France); EPSAM and ISTM, Keele University, Staffordshire ST5 5BG (United Kingdom); Blakeley, Matthew P. [Institut Laue Langevin, 6 Rue Jules Horowitz, 38042 Grenoble (France); Leal, Ricardo M. F. [ILL-EMBL Deuteration Laboratory, Partnership for Structural Biology, 6 Rue Jules Horowitz, 38042 Grenoble (France); Institut Laue Langevin, 6 Rue Jules Horowitz, 38042 Grenoble (France); EPSAM and ISTM, Keele University, Staffordshire ST5 5BG (United Kingdom); ESRF, 6 Rue Jules Horowitz, BP-220, 38043 Grenoble (France); Mitchell, Edward P. [EPSAM and ISTM, Keele University, Staffordshire ST5 5BG (United Kingdom); ESRF, 6 Rue Jules Horowitz, BP-220, 38043 Grenoble (France); Forsyth, V. Trevor, E-mail: tforsyth@ill.fr [ILL-EMBL Deuteration Laboratory, Partnership for Structural Biology, 6 Rue Jules Horowitz, 38042 Grenoble (France); Institut Laue Langevin, 6 Rue Jules Horowitz, 38042 Grenoble (France); EPSAM and ISTM, Keele University, Staffordshire ST5 5BG (United Kingdom)

    2008-05-01

    Preliminary neutron crystallographic data from the sweet protein thaumatin have been recorded using the LADI-III diffractometer at the Institut Laue Langevin (ILL). The results illustrate the feasibility of a full neutron structural analysis aimed at further understanding the molecular basis of the perception of sweet taste. Such an analysis will exploit the use of perdeuterated thaumatin. A preliminary neutron crystallographic study of the sweet protein thaumatin is presented. Large hydrogenated crystals were prepared in deuterated crystallization buffer using the gel-acupuncture method. Data were collected to a resolution of 2 Å on the LADI-III diffractometer at the Institut Laue Langevin (ILL). The results demonstrate the feasibility of a full neutron crystallographic analysis of this structure aimed at providing relevant information on the location of H atoms, the distribution of charge on the protein surface and localized water in the structure. This information will be of interest for understanding the specificity of thaumatin–receptor interactions and will contribute to further understanding of the molecular mechanisms underlying the perception of taste.

  7. Quantum crystallographic charge density of urea.

    Science.gov (United States)

    Wall, Michael E

    2016-07-01

    Standard X-ray crystallography methods use free-atom models to calculate mean unit-cell charge densities. Real molecules, however, have shared charge that is not captured accurately using free-atom models. To address this limitation, a charge density model of crystalline urea was calculated using high-level quantum theory and was refined against publicly available ultra-high-resolution experimental Bragg data, including the effects of atomic displacement parameters. The resulting quantum crystallographic model was compared with models obtained using spherical atom or multipole methods. Despite using only the same number of free parameters as the spherical atom model, the agreement of the quantum model with the data is comparable to the multipole model. The static, theoretical crystalline charge density of the quantum model is distinct from the multipole model, indicating the quantum model provides substantially new information. Hydrogen thermal ellipsoids in the quantum model were very similar to those obtained using neutron crystallography, indicating that quantum crystallography can increase the accuracy of the X-ray crystallographic atomic displacement parameters. The results demonstrate the feasibility and benefits of integrating fully periodic quantum charge density calculations into ultra-high-resolution X-ray crystallographic model building and refinement.

  8. Quantum crystallographic charge density of urea

    Science.gov (United States)

    Wall, Michael E.

    2016-01-01

    Standard X-ray crystallography methods use free-atom models to calculate mean unit-cell charge densities. Real molecules, however, have shared charge that is not captured accurately using free-atom models. To address this limitation, a charge density model of crystalline urea was calculated using high-level quantum theory and was refined against publicly available ultra-high-resolution experimental Bragg data, including the effects of atomic displacement parameters. The resulting quantum crystallographic model was compared with models obtained using spherical atom or multipole methods. Despite using only the same number of free parameters as the spherical atom model, the agreement of the quantum model with the data is comparable to the multipole model. The static, theoretical crystalline charge density of the quantum model is distinct from the multipole model, indicating the quantum model provides substantially new information. Hydrogen thermal ellipsoids in the quantum model were very similar to those obtained using neutron crystallography, indicating that quantum crystallography can increase the accuracy of the X-ray crystallographic atomic displacement parameters. The results demonstrate the feasibility and benefits of integrating fully periodic quantum charge density calculations into ultra-high-resolution X-ray crystallographic model building and refinement. PMID:27437111

  9. Crystal structure of dimethyl 3,4,5,6-tetra-phenyl-cyclo-hexa-3,5-diene-1,2-di-carboxyl-ate.

    Science.gov (United States)

    Greenberg, Fred H; Nazarenko, Alexander Y

    2016-07-01

    In the title compound, C34H28O4, the cyclo-hexa-diene ring has a screw-boat conformation with a torsion angle between the double bonds being on average ca 15° [15.2 (3) and -15.3 (3) in the two independent mol-ecules]. All four phenyl rings in both mol-ecules are arranged in a propeller-like conformation. The two mol-ecules exhibit S,R- and R,S- chirality, respectively, and are connected via C-H⋯O inter-molecular inter-actions. In turn, these weakly bound dimers form the mol-ecular crystal.

  10. Bis(phenyl-phospho-nic) anhydride.

    Science.gov (United States)

    Li, Yang; Hua, Guoxiong; Slawin, Alexandra M Z; Woollins, J Derek

    2009-10-03

    The asymmetric unit of the title compound, C(12)H(12)O(5)P(2), contains four independent mol-ecules, generating two dimers via pairs of inter-molecular O-H⋯O hydrogen bonds, forming R(2) (2)(8) rings. The two aryl rings of each mol-ecule form dihedral angles of 108.6 (1), 103.2 (1), 12.5 (2) and 8.1 (2)° in the four mol-ecules.

  11. (1R,4R,6S,7R)-5,5-Di-bromo-1,4,8,8-tetra-methyl-tri-cyclo-[5.4.1.0(4,6)]dodecan-12-one.

    Science.gov (United States)

    Zaki, Mohamed; Benharref, Ahmed; Daran, Jean-Claude; Berraho, Moha

    2014-05-01

    The title compound, C16H24Br2O, was synthesized from the reaction of β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from Atlas cedar (Cedrus atlantica). The asymmetric unit contains two independent mol-ecules with similar conformations. Each mol-ecule is built up from two fused seven-membered rings and an additional three-membered ring. In both mol-ecules, one of the seven-membered rings has a chair conformation, whereas the other displays a screw-boat conformation.

  12. 4-Chloro-N-(2,5-dimethyl-phen-yl)-2-methyl-benzene-sulfonamide.

    Science.gov (United States)

    Rodrigues, Vinola Z; Foro, Sabine; Gowda, B Thimme

    2011-11-01

    The asymmetric unit of the title compound, C(15)H(16)ClNO(2)S, contains three independent moleules. The conformation of the N-H bonds are anti to the ortho-methyl groups of the sulfonyl benzene rings in all the mol-ecules. The sulfonyl and the aniline benzene rings are tilted relative to each other by 43.0 (2), 37.0 (2) and by 46.0 (1)° in the three mol-ecules. In the crystal, inter-molecular N-H⋯O hydrogen bonds link each of the mol-ecules into centrosymmetric dimers.

  13. World directory of crystallographers and of other scientists employing crystallographic methods

    CERN Document Server

    Filippini, G; Hashizume, H; Torriani, I; Duax, W

    1995-01-01

    The 9th edition of the World Directory of Crystallographers and of Other Scientists Employing Crystallographic Methods, which contains 7907 entries embracing 72 countries, differs considerably from the 8th edition, published in 1990. The content has been updated, and the methods used to acquire the information presented and to produce this new edition of the Directory have involved the latest advances in technology. The Directory is now also available as a regularly updated electronic database, accessible via e-mail, Telnet, Gopher, World-Wide Web, and Mosaic. Full details are given in an Appendix to the printed edition.

  14. Crystal structures of three (trichloromethyl)(carbamoyl)disulfanes.

    Science.gov (United States)

    Goldenberg, Barbara L; Young, Victor G; Barany, George

    2015-10-01

    The present paper reports crystallographic studies on three related compounds that were of inter-est as precursors for synthetic and mechanistic work in organosulfur chemistry, as well as to model nitro-gen-protecting groups: (N-methyl-carbamo-yl)(tri-chloro-meth-yl)disulfane, C3H4Cl3NOS2, (1), (N-benzyl-carbamo-yl)(tri-chloro-meth-yl)disulfane, C9H8Cl3NOS2, (2), and (N-methyl-N-phenyl-carbamo-yl)(tri-chloro-meth-yl)disulfane, C9H8Cl3NOS2, (3). Their mol-ecular structures, with similar bond lengths and angles for the CCl3SS(C=O)N moieties, are confirmed. Compounds (1) and (3) both crystallized with two independent mol-ecules in the asymmetric unit. Classical hydrogen bonding, as well as chlorine-dense regions, are evident in the crystal packing for (1) and (2). In the crystal of (1), mol-ecules are linked via N-H⋯O hydrogen bonds forming chains along [110], which are linked by short Cl⋯Cl and S⋯O contacts forming sheets parallel to (001). In the crystal of (2), mol-ecules are linked via N-H⋯O hydrogen bonds forming chains along [001], which in turn are linked by pairs of short O⋯Cl contacts forming ribbons along the c-axis direction. In the crystal of (3), there are no classical hydrogen bonds present and the chlorine-dense regions observed in (1) and (2) are lacking.

  15. Crystal structure of (E)-4-hy-droxy-N'-(3-meth-oxy-benzyl-idene)benzohydrazide.

    Science.gov (United States)

    Chantrapromma, Suchada; Prachumrat, Patcharawadee; Ruanwas, Pumsak; Boonnak, Nawong; Kassim, Mohammad B

    2016-09-01

    The title compound, C15H14N2O3, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit that differ in the orientation of the 3-meth-oxy-phenyl group with respect to the methyl-idenebenzohydrazide unit. The dihedral angles between the two benzene rings are 24.02 (10) and 29.30 (9)° in mol-ecules A and B, respectively. In mol-ecule A, the meth-oxy group is twisted slightly relative to its bound benzene ring, with a Cmeth-yl-O-C-C torsion angle of 14.2 (3)°, whereas it is almost co-planar in mol-ecule B, where the corresponding angle is -2.4 (3)°. In the crystal, the mol-ecules are linked by N-H⋯O, O-H⋯N and O-H⋯O hydrogen bonds, as well as by weak C-H⋯O inter-actions, forming sheets parallel to the bc plane. The N-H⋯O hydrogen bond and weak C-H⋯O inter-action link different mol-ecules (A⋯B) whereas both O-H⋯N and O-H⋯O hydrogen bonds link like mol-ecules (A⋯A) and (B⋯B). Pairs of inversion-related B mol-ecules are stacked approximately along the a axis by π-π inter-actions in which the distance between the centroids of the 3-meth-oxy-phenyl rings is 3.5388 (12) Å. The B mol-ecules also participate in weak C-H⋯π inter-actions between the 4-hy-droxy-phenyl and the 3-meth-oxy-phenyl rings.

  16. Crystallographic Analysis of Tapering of ADP Crystallites

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    On the basis of crystallographic characteristics of ADP (ammonium dihydrogen phosphate) crystals and the selected growth conditions, the growth habit of ADP crystals was studied. In comparison with pyramidal planes, the growth rate of prismatic faces is slower and more sensitive to the additives and impurities for ADP crystals. When the supersaturation is low, the advance of growth steps on prismatic face can be blocked by ethanol or impurities, the crystal morphology is changed from the tetragonal prism to shuttle (i.e., the tapered shape). The tapering formation of ADP crystallites was structurally studied in a novel view.

  17. Transuranic Hybrid Materials: Crystallographic and Computational Metrics of Supramolecular Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Surbella, Robert G. [Department; Ducati, Lucas C. [Department; Pellegrini, Kristi L. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; McNamara, Bruce K. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Autschbach, Jochen [Department; Schwantes, Jon M. [Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99354, United States; Cahill, Christopher L. [Department

    2017-07-26

    A family of twelve supramolecular [AnO2Cl4]2- (An = U, Np, Pu) containing compounds assembled via hydrogen and halogen bonds donated by substituted 4-X-pyridinium cations (X = H, Cl, Br, I) is reported. These materials were prepared from a room-temperature synthesis wherein crystallization of unhydrolyzed and valence pure [An(VI)O2Cl4]2- (An = U, Np, Pu) tectons are the norm. We present a hierarchy of assembly criteria based on crystallographic observations, and subsequently quantify the strengths of the non-covalent interactions using Kohn-Sham density functional calculations. We provide, for the first time, a detailed description of the electrostatic potentials (ESPs) of the actinyl tetrahalide dianions and reconcile crystallographically observed structural motifs and non-covalent interaction (NCI) acceptor-donor pairings. Our findings indicate that the average electrostatic potential across the halogen ligands (the acceptors) changes by only ~2 kJ mol-1 across the AnO22+ series, indicating the magnitude of the potential is independent of the metal center. The role of the cation is therefore critical in directing structural motifs and dictating the resulting hydrogen and halogen bond strengths, the former being stronger due to the positive charge centralized on the pyridyl nitrogen N-H+. Subsequent analyses using the Quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) approaches support this conclusion and highlight the structure directing role of the cations. Whereas one can infer that the 2 Columbic attraction is the driver for assembly, the contribution of the non-covalent interaction is to direct the molecular-level arrangement (or disposition) of the tectons.

  18. Orbits of crystallographic embedding of non-crystallographic groups and applications to virology.

    Science.gov (United States)

    Twarock, Reidun; Valiunas, Motiejus; Zappa, Emilio

    2015-11-01

    The architecture of infinite structures with non-crystallographic symmetries can be modelled via aperiodic tilings, but a systematic construction method for finite structures with non-crystallographic symmetry at different radial levels is still lacking. This paper presents a group theoretical method for the construction of finite nested point sets with non-crystallographic symmetry. Akin to the construction of quasicrystals, a non-crystallographic group G is embedded into the point group P of a higher-dimensional lattice and the chains of all G-containing subgroups are constructed. The orbits of lattice points under such subgroups are determined, and it is shown that their projection into a lower-dimensional G-invariant subspace consists of nested point sets with G-symmetry at each radial level. The number of different radial levels is bounded by the index of G in the subgroup of P. In the case of icosahedral symmetry, all subgroup chains are determined explicitly and it is illustrated that these point sets in projection provide blueprints that approximate the organization of simple viral capsids, encoding information on the structural organization of capsid proteins and the genomic material collectively, based on two case studies. Contrary to the affine extensions previously introduced, these orbits endow virus architecture with an underlying finite group structure, which lends itself better to the modelling of dynamic properties than its infinite-dimensional counterpart.

  19. Collaborative annotation of 3D crystallographic models.

    Science.gov (United States)

    Hunter, J; Henderson, M; Khan, I

    2007-01-01

    This paper describes the AnnoCryst system-a tool that was designed to enable authenticated collaborators to share online discussions about 3D crystallographic structures through the asynchronous attachment, storage, and retrieval of annotations. Annotations are personal comments, interpretations, questions, assessments, or references that can be attached to files, data, digital objects, or Web pages. The AnnoCryst system enables annotations to be attached to 3D crystallographic models retrieved from either private local repositories (e.g., Fedora) or public online databases (e.g., Protein Data Bank or Inorganic Crystal Structure Database) via a Web browser. The system uses the Jmol plugin for viewing and manipulating the 3D crystal structures but extends Jmol by providing an additional interface through which annotations can be created, attached, stored, searched, browsed, and retrieved. The annotations are stored on a standardized Web annotation server (Annotea), which has been extended to support 3D macromolecular structures. Finally, the system is embedded within a security framework that is capable of authenticating users and restricting access only to trusted colleagues.

  20. X-ray crystallographic studies of metalloproteins.

    Science.gov (United States)

    Volbeda, Anne

    2014-01-01

    Many proteins require metals for their physiological function. In combination with spectroscopic characterizations, X-ray crystallography is a very powerful method to correlate the function of protein-bound metal sites with their structure. Due to their special X-ray scattering properties, specific metals may be located in metalloprotein structures and eventually used for phasing the diffracted X-rays by the method of Multi-wavelength Anomalous Dispersion (MAD). How this is done is the principle subject of this chapter. Attention is also given to the crystallographic characterization of different oxidation states of redox active metals and to the complication of structural changes that may be induced by X-ray irradiation of protein crystals.

  1. The X-ray system of crystallographic programs for any computer having a PIDGIN FORTRAN compiler

    Science.gov (United States)

    Stewart, J. M.; Kruger, G. J.; Ammon, H. L.; Dickinson, C.; Hall, S. R.

    1972-01-01

    A manual is presented for the use of a library of crystallographic programs. This library, called the X-ray system, is designed to carry out the calculations required to solve the structure of crystals by diffraction techniques. It has been implemented at the University of Maryland on the Univac 1108. It has, however, been developed and run on a variety of machines under various operating systems. It is considered to be an essentially machine independent library of applications programs. The report includes definition of crystallographic computing terms, program descriptions, with some text to show their application to specific crystal problems, detailed card input descriptions, mass storage file structure and some example run streams.

  2. (E)-1-[2-Hy-droxy-4,6-bis-(meth-oxy-meth-oxy)phen-yl]-3-[3-meth-oxy-4-(meth-oxy-meth-oxy)phen-yl]prop-2-en-1-one.

    Science.gov (United States)

    Chang, Liu-Shuan; Li, Chen-Yang; Zhao, Yan-Mei; Xu, Fang; Gu, Zheng-Yi

    2011-11-01

    The title compound, C(22)H(26)O(9), crystallizes with two independent mol-ecules in the asymmetric unit in which the dihedral angles between the two benzene rings are 21.4 (2) and 5.1 (2)°. An intra-molecular O-H⋯O hydrogen bond occurs in each mol-ecule. Inter-molecular C-H⋯O hydrogen bonds stabilize the crystal structure.

  3. (E)-1-Benzyl-idene-2,2-diphenyl-hydrazine.

    Science.gov (United States)

    Mendoza, Angel; Meléndrez-Luevano, Ruth; Cabrera-Vivas, Blanca M; Lozano-Márquez, Claudia D; Carranza, Vladimir

    2012-02-01

    The asymmetric unit of the title compound, C(19)H(16)N(2), contains two independent mol-ecules, both of which show an E configuration with respect to the C=N bond. The dihedral angles between the phenyl rings bonded to the hydrazine group are 81.00 (10) and 88.34 (8)° in the two mol-ecules. Inter-molecular C-H⋯π inter-actions are observed in the crystal structure.

  4. N-(3-Chloro-phen-yl)-4-nitro-benzene-sulfonamide.

    Science.gov (United States)

    Chaithanya, U; Foro, Sabine; Gowda, B Thimme

    2012-12-01

    There are two independent mol-ecules in the asymmetric unit of the title compound, C12H9ClN2O4S, in which the dihedral angles between the planes of the benzene rings are 46.90 (14) and 44.50 (14)°. In the crystal, N-H⋯O hydrogen bonds link the mol-ecules into zigzag chains parallel to the a axis.

  5. N-(3,5-Dimethyl-phen-yl)-4-nitro-benzene-sulfonamide.

    Science.gov (United States)

    Chaithanya, U; Foro, Sabine; Gowda, B Thimme

    2012-12-01

    There are two independent mol-ecules in the asymmetric unit of the title compound, C14H14N2O4S, in which the dihedral angles between the benzene rings are 56.22 (15) and 58.16 (14)°. In the crystal, N-H⋯Onitro hydrogen bonds link the mol-ecules into zigzag chains running along the a-axis direction.

  6. N-(3-Methyl-benzo-yl)benzene-sulfonamide.

    Science.gov (United States)

    Suchetan, P A; Foro, Sabine; Gowda, B Thimme

    2012-05-01

    The asymmetric unit of the title compound, C(14)H(13)NO(3)S, contains three independent mol-ecules in which the dihedral angles between the sulfonyl and benzoyl benzene rings are 83.3 (2), 84.4 (2) and 87.6 (2)°. In the crystal, mol-ecules are linked into chains running along the a axis via N-H⋯O hydrogen bonds.

  7. Crystallographic structure of ubiquitin in complex with cadmium ions

    Directory of Open Access Journals (Sweden)

    Cheung Peter

    2009-12-01

    Full Text Available Abstract Background Ubiquitination plays a critical role in regulating many cellular processes, from DNA repair and gene transcription to cell cycle and apoptosis. It is catalyzed by a specific enzymatic cascade ultimately leading to the conjugation of ubiquitin to lysine residues of the target protein that can be the ubiquitin molecule itself and to the formation of poly-ubiquitin chains. Findings We present the crystal structure at 3.0 Å resolution of bovine ubiquitin crystallized in presence of cadmium ions. Two molecules of ubiquitin are present in the asymmetric unit. Interestingly this non-covalent dimeric arrangement brings Lys-6 and Lys-63 of each crystallographically-independent monomer in close contact with the C-terminal ends of the other monomer. Residues Leu-8, Ile-44 and Val-70 that form a hydrophobic patch at the surface of the Ub monomer are trapped at the dimer interface. Conclusions The structural basis for signalling by poly-Ub chains relies on a visualization of conformations of alternatively linked poly-Ub chains. This arrangement of ubiquitin could illustrate how linkages involving Lys-6 or Lys-63 of ubiquitin are produced in the cell. It also details how ubiquitin molecules can specifically chelate cadmium ions.

  8. Correlating Atom Probe Crystallographic Measurements with Transmission Kikuchi Diffraction Data.

    Science.gov (United States)

    Breen, Andrew J; Babinsky, Katharina; Day, Alec C; Eder, K; Oakman, Connor J; Trimby, Patrick W; Primig, Sophie; Cairney, Julie M; Ringer, Simon P

    2017-03-14

    Correlative microscopy approaches offer synergistic solutions to many research problems. One such combination, that has been studied in limited detail, is the use of atom probe tomography (APT) and transmission Kikuchi diffraction (TKD) on the same tip specimen. By combining these two powerful microscopy techniques, the microstructure of important engineering alloys can be studied in greater detail. For the first time, the accuracy of crystallographic measurements made using APT will be independently verified using TKD. Experimental data from two atom probe tips, one a nanocrystalline Al-0.5Ag alloy specimen collected on a straight flight-path atom probe and the other a high purity Mo specimen collected on a reflectron-fitted instrument, will be compared. We find that the average minimum misorientation angle, calculated from calibrated atom probe reconstructions with two different pole combinations, deviate 0.7° and 1.4°, respectively, from the TKD results. The type of atom probe and experimental conditions appear to have some impact on this accuracy and the reconstruction and measurement procedures are likely to contribute further to degradation in angular resolution. The challenges and implications of this correlative approach will also be discussed.

  9. Crystallographic orientation dependent etching of graphene layers

    Energy Technology Data Exchange (ETDEWEB)

    Nemes-Incze, Peter; Biro, Laszlo Peter [Research Institute for Technical Physics and Materials Science, PO. Box 49, 1525 Budapest (Hungary); Magda, Gabor [Budapest University of Technology and Economics (BME), PO Box 91, 1521 Budapest (Hungary); Kamaras, Katalin [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, PO Box 49, 1525, Budapest (Hungary)

    2010-04-15

    Graphene has gripped the scientific community ever since its discovery in 2004, with very promising electronic properties and hopes to integrate graphene into nanoelectronic devices. For graphene to make its way into electronic devices, two major obstacles have to be overcome: reproducible preparation of large area graphene samples and patterning techniques to obtain functional components. In this paper we present a graphene etching technique, which is crystallographic orientation selective and allows for the patterning of graphene layers using a chemical reduction process. The process involves the reduction of the SiO{sub 2} support by the carbon in the graphene itself. This reaction only occurs at the sample edges and does not result in the degradation of the graphene crystal lattice itself. However, we have observed evidence of strong hole doping in our etched samples. This etching technique opens up new possibilities in graphene patterning and modification. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Determination of crystallographic intensities from sparse data

    Directory of Open Access Journals (Sweden)

    Kartik Ayyer

    2015-01-01

    Full Text Available X-ray serial microcrystallography involves the collection and merging of frames of diffraction data from randomly oriented protein microcrystals. The number of diffracted X-rays in each frame is limited by radiation damage, and this number decreases with crystal size. The data in the frame are said to be sparse if too few X-rays are collected to determine the orientation of the microcrystal. It is commonly assumed that sparse crystal diffraction frames cannot be merged, thereby setting a lower limit to the size of microcrystals that may be merged with a given source fluence. The EMC algorithm [Loh & Elser (2009, Phys. Rev. E, 80, 026705] has previously been applied to reconstruct structures from sparse noncrystalline data of objects with unknown orientations [Philipp et al. (2012, Opt. Express, 20, 13129–13137; Ayyer et al. (2014, Opt. Express, 22, 2403–2413]. Here, it is shown that sparse data which cannot be oriented on a per-frame basis can be used effectively as crystallographic data. As a proof-of-principle, reconstruction of the three-dimensional diffraction intensity using sparse data frames from a 1.35 kDa molecule crystal is demonstrated. The results suggest that serial microcrystallography is, in principle, not limited by the fluence of the X-ray source, and collection of complete data sets should be feasible at, for instance, storage-ring X-ray sources.

  11. Crystallographic interpretation of Galois symmetries for magnetic pentagonal ring

    Science.gov (United States)

    Milewski, J.; Lulek, T.; Łabuz, M.

    2017-03-01

    Galois symmetry of exact Bethe Ansatz eigenstates for the magnetic pentagonal ring within the XXX model are investigated by a comparison with crystallographic constructions of space groups. It follows that the arithmetic symmetry of Bethe parameters for the interior of the Brillouin zone admits crystallographic interpretation, in terms of the periodic square Z2 ×Z2 , that is the two-dimensional crystal lattice with Born-Karman period two in both directions.

  12. N-Ethyl-2-[1-(2-hy-droxy-4-methyl-phen-yl)ethyl-idene]hydrazinecarbo-thio-amide.

    Science.gov (United States)

    Anderson, Brian J; Hall, Jeffrey R; Jasinski, Jerry P

    2014-06-01

    The title compound, C12H17N3OS, crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. The dihedral angle between the mean planes of the benzene ring and the hydrazinecarbo-thio-amide group are 6.9 (4) and 37.2 (5)° in mol-ecules A and B, respectively. An intra-molecular O-H⋯N hydrogen bond is observed in each mol-ecule. This serves to maintain an approximately planar conformation for mol-ecule A, but leaves a significant twist between these two groups in mol-ecule B. In the crystal, a weak N-H⋯S inter-action is observed, forming inversion dimers among the B mol-ecules and resulting in an R 2 (2)(8) motif. These dimers are further inter-connected by weak N-H⋯O and C-H⋯O inter-molecular inter-actions, forming chains along [011].

  13. Calculation of Crystallographic Texture of BCC Steels During Cold Rolling

    Science.gov (United States)

    Das, Arpan

    2017-05-01

    BCC alloys commonly tend to develop strong fibre textures and often represent as isointensity diagrams in φ 1 sections or by fibre diagrams. Alpha fibre in bcc steels is generally characterised by crystallographic axis parallel to the rolling direction. The objective of present research is to correlate carbon content, carbide dispersion, rolling reduction, Euler angles (ϕ) (when φ 1 = 0° and φ 2 = 45° along alpha fibre) and the resulting alpha fibre texture orientation intensity. In the present research, Bayesian neural computation has been employed to correlate these and compare with the existing feed-forward neural network model comprehensively. Excellent match to the measured texture data within the bounding box of texture training data set has been already predicted through the feed-forward neural network model by other researchers. Feed-forward neural network prediction outside the bounds of training texture data showed deviations from the expected values. Currently, Bayesian computation has been similarly applied to confirm that the predictions are reasonable in the context of basic metallurgical principles, and matched better outside the bounds of training texture data set than the reported feed-forward neural network. Bayesian computation puts error bars on predicted values and allows significance of each individual parameters to be estimated. Additionally, it is also possible by Bayesian computation to estimate the isolated influence of particular variable such as carbon concentration, which exactly cannot in practice be varied independently. This shows the ability of the Bayesian neural network to examine the new phenomenon in situations where the data cannot be accessed through experiments.

  14. 1-(3-Bromo-2-thien-yl)ethanone.

    Science.gov (United States)

    Mahendra, M; Vivek, H K; Gaonkar, S L; Priya, B S; Nanjunda Swamy, S

    2010-09-11

    In the title compound, C(6)H(5)BrOS, the non-H and aromatic H atoms lie on a crystallographic mirror plane. In the crystal, mol-ecules are linked into chains propagating along the c axis by inter-molecular C-H⋯O hydrogen bonds.

  15. Crystal structure of 1,1'-[imidazolidine-1,3-diylbis(methyl-ene)]bis-(naphthalen-2-ol).

    Science.gov (United States)

    Rivera, Augusto; Rojas, Jicli José; Ríos-Motta, Jaime; Bolte, Michael

    2015-03-01

    The crystal structure of the title compound, C25H24N2O2, at 173 K has monoclinic (C2/c) symmetry. The mol-ecule is located on a crystallographic twofold rotation axis with only half a mol-ecule in the asymmetric unit. The imidazolidine ring adopts a twist conformation, with a twist about the ring C-C bond. The crystal structure shows the anti-clinal disposition of the two (2-hy-droxy-naphthalen-1-yl)methyl substituents of the imidazolidine ring. The structure displays two intra-molecular O-H⋯N hydrogen bonds, each forming an S(6) ring motif.

  16. Crystal structure of an organic-inorganic hybrid compound based on morpholinium cations and a β-type Anderson polyanion.

    Science.gov (United States)

    Lukianova, Tamara J; Kinzhybalo, Vasyl; Pietraszko, Adam

    2015-11-01

    A new organic-inorganic hybrid compound, penta-morpholinium hexa-hydrogen hexa-molybdoferrate(III) sulfate 3.5-hydrate, (C4H10NO)5[Fe(III)(OH)6Mo6O18](SO4)·3.5H2O, was obtained from an aqueous solution. The polyoxidomolybdate (POM) anion is of the Anderson β-type with a central Fe(III) ion. Three of five crystallographically independent morpholinium cations are disordered over two sets of sites. An intricate network of inter-molecular N-H⋯O and O-H⋯O inter-actions between cations, POMs, sulfate anions and non-coordinating water mol-ecules creates a three-dimensional network structure.

  17. Poly[[aquadi-μ(3)-malonato-hexaphenyl-ditin(IV)] acetone solvate].

    Science.gov (United States)

    Win, Yip Foo; Teoh, Siang Guan; Vikneswaran, M R; Goh, Jia Hao; Fun, Hoong-Kun

    2010-05-22

    The asymmetric unit of the title polymeric complex, {[Sn(2)=(C(6)H(5))(6)(C(3)H(2)O(4))(H(2)O)]·C(3)H(6)O}(n), comprises of two Sn cations, one malonate anion and a non-coordinating acetone solvent mol-ecule. Both crystallographically independent Sn cations are five-coordinated by two O and three C atoms in a distorted trigonal-bipyrimidal geometry. One of the Sn cations is bridged by the malonate units, affording polymeric chains which run along [001]. Weak intra-molecular C-H⋯π inter-actions stabilize the mol-ecular structure. In the crystal structure, adjacent chains are inter-connected by inter-molecular O-H⋯O and C-H⋯O hydrogen bonds into a three-dimensional supra-molecular structure. A weak inter-molecular C-H⋯π inter-action is also observed.

  18. Crystallographic effects during micromachining — A finite-element model

    Science.gov (United States)

    Song, Shin-Hyung; Choi, Woo Chun

    2015-07-01

    Mechanical micromachining is a powerful and effective way for manufacturing small sized machine parts. Even though the micromachining process is similar to the traditional machining, the material behavior during the process is much different. In particular, many researchers report that the basic mechanics of the work material is affected by microstructures and their crystallographic orientations. For example, crystallographic orientations of the work material have significant influence on force response, chip formation and surface finish. In order to thoroughly understand the effect of crystallographic orientations on the micromachining process, finite-element model (FEM) simulating orthogonal cutting process of single crystallographic material was presented. For modeling the work material, rate sensitive single crystal plasticity of face-centered cubic (FCC) crystal was implemented. For the chip formation during the simulation, element deletion technique was used. The simulation model is developed using ABAQUS/explicit with user material subroutine via user material subroutine (VUMAT). Simulations showed that variation of the specific cutting energy at different crystallographic orientations of work material shows significant anisotropy. The developed FEM model can be a useful prediction tool of micromachining of crystalline materials.

  19. Crystallographic orientation and concentric layers in spicules of calcareous sponges.

    Science.gov (United States)

    Rossi, André Linhares; Ribeiro, Bárbara; Lemos, Moara; Werckmann, Jacques; Borojevic, Radovan; Fromont, Jane; Klautau, Michelle; Farina, Marcos

    2016-11-01

    In this work, the crystallography of calcareous sponges (Porifera) spicules and the organization pattern of the concentric layers present in their inner structure were investigated in 10 species of the subclass Calcaronea and three species of the subclass Calcinea. Polished spicules had specific concentric patterns that varied depending on the plane in which the spicules were sectioned. A 3D model of the concentric layers was created to interpret these patterns and the biomineralization process of the triactine spicules. The morphology of the spicules was compared with the crystallographic orientation of the calcite crystals by analyzing the Kikuchi diffraction patterns using a scanning electron microscope. Triactine spicules from the subclass Calcinea had actines (rays) elongated in the 〈210〉 direction, which is perpendicular to the c-axis. The scale spicules of the hypercalcified species Murrayona phanolepis presented the c-axis perpendicular to the plane of the scale, which is in accordance with the crystallography of all other Calcinea. The triactine spicules of the calcaronean species had approximately the same crystallographic orientation with the unpaired actine elongated in the ∼[211] direction. Only one Calcaronea species, whose triactine was regular, had a different orientation. Three different crystallographic orientations were found in diactines. Spicules with different morphologies, dimensions and positions in the sponge body had similar crystallographic directions suggesting that the crystallographic orientation of spicules in calcareous sponges is conserved through evolution. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. 4-(Piperidin-1-yl)-4H-benzo[b]tetra-zolo[1,5-d][1,4]diazepin-5(6H)-one.

    Science.gov (United States)

    Nichol, Gary S; Xu, Zhigang; Kaiser, Christine E; Hulme, Christopher

    2010-12-04

    There are two crystallographically unique mol-ecules present in the asymmetric unit of the title compound, C(14)H(16)N(6)O; in both mol-ecules, the seven-membered diazepinone ring adopts a boat-like conformation and the chair conformation piperidine ring is an axial substituent on the diazepinone ring. In the crystal, each mol-ecule forms hydrogen bonds with its respective symmetry equivalents. Hydrogen bonding between mol-ecule A and symmetry equivalents forms two ring motifs, the first formed by inversion-related N-H⋯O inter-actions and the second formed by C-H⋯O and C-H⋯N inter-actions. The combination of both ring motifs results in the formation of an infinite double tape, which propagates in the a-axis direction. Hydrogen bonding between mol-ecule B and symmetry equivalents forms one ring motif by inversion-related N-H⋯O inter-actions and a second ring motif by C-H⋯O inter-actions, which propagate as a single tape parallel with the c axis.

  1. Di-μ-acetato-μ-aqua-bis-[acetatobis(1H-benzimidazole)cobalt(II)].

    Science.gov (United States)

    Zimmermann, Iwan; Keene, Tony D; Neels, Antonia; Decurtins, Silvio

    2008-05-30

    In the title compound, [Co(2)(C(2)H(3)O(2))(4)(C(7)H(6)N(2))(4)(H(2)O)], the half-mol-ecule in the asymmetric unit is completed by a crystallographic twofold rotation axis to give the full mol-ecule. The Co(II) ions are approximately octahedrally coordinated with a cis-N(2)O(4) coordination sphere. The compound features intra-molecular O-H⋯O hydrogen bonds between the non-bridging acetate groups and the bridging water mol-ecule, and inter-molecular N-H⋯O hydrogen bonds between the acetates and amine H atoms of the benzimidazoles which determine the mol-ecular packing in the crystal structure.

  2. Crystallographic Topology 2: Overview and Work in Progress

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, C.K.

    1999-08-01

    This overview describes an application of contemporary geometric topology and stochastic process concepts to structural crystallography. In this application, crystallographic groups become orbifolds, crystal structures become Morse functions on orbifolds, and vibrating atoms in a crystal become vector valued Gaussian measures with the Radon-Nikodym property. Intended crystallographic benefits include new methods for visualization of space groups and crystal structures, analysis of the thermal motion patterns seen in ORTEP drawings, and a classification scheme for crystal structures based on their Heegaard splitting properties.

  3. Crystal structures of three N-(aryl-sulfon-yl)-4-fluoro-benzamides.

    Science.gov (United States)

    Suchetan, P A; Naveen, S; Lokanath, N K; Srivishnu, K S; Supriya, G M; Lakshmikantha, H N

    2016-04-01

    The crystal structures of three N-aryl-sulfonyl-4-fluoro-benzamides, namely 4-fluoro-N-(2-methyl-phenyl-sulfon-yl)benzamide, C14H12FNO3S, (I), N-(2-chloro-phenyl-sulfon-yl)-4-fluorobenzamide, C13H9ClFNO3S, (II), and N-(4-chloro-phenyl-sulfon-yl)-4-fluoro-benzamide monohydrate, C13H9ClFNO3S·H2O, (III), are described and compared with related structures. The asymmetric unit of (I) contains two independent mol-ecules (A and B), while that of (II) contains just one mol-ecule, and that of (III) contains a mol-ecule of water in addition to one main mol-ecule. The dihedral angle between the benzene rings is 82.83 (11)° in mol-ecule A and 85.01 (10)° in mol-ecule B of (I), compared to 89.91 (10)° in (II) and 81.82 (11)° in (III). The crystal structure of (I) features strong N-H⋯O hydrogen bonds between the A and B mol-ecules, resulting in an R 4 (4)(16) tetra-meric unit. These tetra-meric units are connected into sheets in the bc plane by various C-H⋯O inter-actions, and adjacent sheets are further inter-linked via C-H⋯πar-yl inter-actions, forming a three-dimensional architecture. The crystal structure is further stabilized by πar-yl-πar-yl and S=O⋯πar-yl inter-actions. In the crystal of (II), mol-ecules are connected into R 2 (2)(8) and R 2 (2)(14) dimers via N-H⋯O hydrogen bonds and C-H⋯O inter-actions, respectively; the dimers are further inter-connected via a weak C=O⋯πar-yl inter-action, leading to the formation of chains along [1-10]. In the crystal of (III), N-H⋯O and O-H⋯O hydrogen bonds involving both the main mol-ecule and the solvent water mol-ecule results in the formation of sheets parallel to the bc plane. The sheets are further connected by C-H⋯O inter-actions and weak C-Cl⋯πar-yl, C-F⋯πar-yl and S=O⋯πar-yl inter-actions, forming a three-dimensional architecture.

  4. Crystal structure refinement a crystallographers guide to SHELXL

    CERN Document Server

    2006-01-01

    A crystallographers guide to SHELXL, covering various aspects of practical crystal structure refinement, from the treatment of hydrogen atoms to the assignment of atom types, and more. After an introduction to SHELXL, a brief survey of crystal structure refinement is provided.

  5. Recovery of crystallographic texture in remineralized dental enamel.

    Science.gov (United States)

    Siddiqui, Samera; Anderson, Paul; Al-Jawad, Maisoon

    2014-01-01

    Dental caries is the most prevalent disease encountered by people of all ages around the world. Chemical changes occurring in the oral environment during the caries process alter the crystallography and microstructure of dental enamel resulting in loss of mechanical function. Little is known about the crystallographic effects of demineralization and remineralization. The motivation for this study was to develop understanding of the caries process at the crystallographic level in order to contribute towards a long term solution. In this study synchrotron X-ray diffraction combined with scanning electron microscopy and scanning microradiography have been used to correlate enamel crystallography, microstructure and mineral concentration respectively in enamel affected by natural caries and following artificial demineralization and remineralization regimes. In particular, the extent of destruction and re-formation of this complex structure has been measured. 2D diffraction patterns collected at the European Synchrotron Radiation Facility were used to quantify changes in the preferred orientation (crystallographic texture) and position of the (002) Bragg reflection within selected regions of interest in each tooth slice, and then correlated with the microstructure and local mineral mass. The results revealed that caries and artificial demineralization cause a large reduction in crystallographic texture which is coupled with the loss of mineral mass. Remineralization restores the texture to the original level seen in healthy enamel and restores mineral density. The results also showed that remineralization promotes ordered formation of new crystallites and growth of pre-existing crystallites which match the preferred orientation of healthy enamel. Combining microstructural and crystallographic characterization aids the understanding of caries and erosion processes and assists in the progress towards developing therapeutic treatments to allow affected enamel to regain

  6. Crystallographic Mapping of Guided Nanowires by Second Harmonic Generation Polarimetry.

    Science.gov (United States)

    Neeman, Lior; Ben-Zvi, Regev; Rechav, Katya; Popovitz-Biro, Ronit; Oron, Dan; Joselevich, Ernesto

    2017-02-08

    The growth of horizontal nanowires (NWs) guided by epitaxial and graphoepitaxial relations with the substrate is becoming increasingly attractive owing to the possibility of controlling their position, direction, and crystallographic orientation. In guided NWs, as opposed to the extensively characterized vertically grown NWs, there is an increasing need for understanding the relation between structure and properties, specifically the role of the epitaxial relation with the substrate. Furthermore, the uniformity of crystallographic orientation along guided NWs and over the substrate has yet to be checked. Here we perform highly sensitive second harmonic generation (SHG) polarimetry of polar and nonpolar guided ZnO NWs grown on R-plane and M-plane sapphire. We optically map large areas on the substrate in a nondestructive way and find that the crystallographic orientations of the guided NWs are highly selective and specific for each growth direction with respect to the substrate lattice. In addition, we perform SHG polarimetry along individual NWs and find that the crystallographic orientation is preserved along the NW in both polar and nonpolar NWs. While polar NWs show highly uniform SHG along their axis, nonpolar NWs show a significant change in the local nonlinear susceptibility along a few micrometers, reflected in a reduction of 40% in the ratio of the SHG along different crystal axes. We suggest that these differences may be related to strain accumulation along the nonpolar wires. We find SHG polarimetry to be a powerful tool to study both selectivity and uniformity of crystallographic orientations of guided NWs with different epitaxial relations.

  7. Recovery of crystallographic texture in remineralized dental enamel.

    Directory of Open Access Journals (Sweden)

    Samera Siddiqui

    Full Text Available Dental caries is the most prevalent disease encountered by people of all ages around the world. Chemical changes occurring in the oral environment during the caries process alter the crystallography and microstructure of dental enamel resulting in loss of mechanical function. Little is known about the crystallographic effects of demineralization and remineralization. The motivation for this study was to develop understanding of the caries process at the crystallographic level in order to contribute towards a long term solution. In this study synchrotron X-ray diffraction combined with scanning electron microscopy and scanning microradiography have been used to correlate enamel crystallography, microstructure and mineral concentration respectively in enamel affected by natural caries and following artificial demineralization and remineralization regimes. In particular, the extent of destruction and re-formation of this complex structure has been measured. 2D diffraction patterns collected at the European Synchrotron Radiation Facility were used to quantify changes in the preferred orientation (crystallographic texture and position of the (002 Bragg reflection within selected regions of interest in each tooth slice, and then correlated with the microstructure and local mineral mass. The results revealed that caries and artificial demineralization cause a large reduction in crystallographic texture which is coupled with the loss of mineral mass. Remineralization restores the texture to the original level seen in healthy enamel and restores mineral density. The results also showed that remineralization promotes ordered formation of new crystallites and growth of pre-existing crystallites which match the preferred orientation of healthy enamel. Combining microstructural and crystallographic characterization aids the understanding of caries and erosion processes and assists in the progress towards developing therapeutic treatments to allow affected

  8. Applied and implied semantics in crystallographic publishing

    Directory of Open Access Journals (Sweden)

    McMahon Brian

    2012-08-01

    Full Text Available Abstract Background Crystallography is a data-rich, software-intensive scientific discipline with a community that has undertaken direct responsibility for publishing its own scientific journals. That community has worked actively to develop information exchange standards allowing readers of structure reports to access directly, and interact with, the scientific content of the articles. Results Structure reports submitted to some journals of the International Union of Crystallography (IUCr can be automatically validated and published through an efficient and cost-effective workflow. Readers can view and interact with the structures in three-dimensional visualization applications, and can access the experimental data should they wish to perform their own independent structure solution and refinement. The journals also layer on top of this facility a number of automated annotations and interpretations to add further scientific value. Conclusions The benefits of semantically rich information exchange standards have revolutionised the scholarly publishing process for crystallography, and establish a model relevant to many other physical science disciplines.

  9. Crystallographic data processing for free-electron laser sources

    Energy Technology Data Exchange (ETDEWEB)

    White, Thomas A., E-mail: taw@physics.org; Barty, Anton; Stellato, Francesco [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Holton, James M. [University of California, San Francisco, CA 94158 (United States); Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kirian, Richard A. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); Arizona State University, Tempe, AZ 85287 (United States); Zatsepin, Nadia A. [Arizona State University, Tempe, AZ 85287 (United States); Chapman, Henry N. [DESY, Notkestrasse 85, 22607 Hamburg (Germany); University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2013-07-01

    A processing pipeline for diffraction data acquired using the ‘serial crystallography’ methodology with a free-electron laser source is described with reference to the crystallographic analysis suite CrystFEL and the pre-processing program Cheetah. A processing pipeline for diffraction data acquired using the ‘serial crystallography’ methodology with a free-electron laser source is described with reference to the crystallographic analysis suite CrystFEL and the pre-processing program Cheetah. A detailed analysis of the nature and impact of indexing ambiguities is presented. Simulations of the Monte Carlo integration scheme, which accounts for the partially recorded nature of the diffraction intensities, are presented and show that the integration of partial reflections could be made to converge more quickly if the bandwidth of the X-rays were to be increased by a small amount or if a slight convergence angle were introduced into the incident beam.

  10. Crystallographic changes in lead zirconate titanate due to neutron irradiation

    Directory of Open Access Journals (Sweden)

    Alexandra Henriques

    2014-11-01

    Full Text Available Piezoelectric and ferroelectric materials are useful as the active element in non-destructive monitoring devices for high-radiation areas. Here, crystallographic structural refinement (i.e., the Rietveld method is used to quantify the type and extent of structural changes in PbZr0.5Ti0.5O3 after exposure to a 1 MeV equivalent neutron fluence of 1.7 × 1015 neutrons/cm2. The results show a measurable decrease in the occupancy of Pb and O due to irradiation, with O vacancies in the tetragonal phase being created preferentially on one of the two O sites. The results demonstrate a method by which the effects of radiation on crystallographic structure may be investigated.

  11. A crystallographic perspective on sharing data and knowledge.

    Science.gov (United States)

    Bruno, Ian J; Groom, Colin R

    2014-10-01

    The crystallographic community is in many ways an exemplar of the benefits and practices of sharing data. Since the inception of the technique, virtually every published crystal structure has been made available to others. This has been achieved through the establishment of several specialist data centres, including the Cambridge Crystallographic Data Centre, which produces the Cambridge Structural Database. Containing curated structures of small organic molecules, some containing a metal, the database has been produced for almost 50 years. This has required the development of complex informatics tools and an environment allowing expert human curation. As importantly, a financial model has evolved which has, to date, ensured the sustainability of the resource. However, the opportunities afforded by technological changes and changing attitudes to sharing data make it an opportune moment to review current practices.

  12. Recent developments in crystallographic investigation of martensitic transformation

    Institute of Scientific and Technical Information of China (English)

    GU Nanju; DONG Guixia; LIN Xiaoping; WANG Baoqi; MA Xiaoli

    2004-01-01

    The results and new knowledge obtained in recent years by using an atom force microscope (AFM) to investigate the surface relieves and to reveal the lattice deformation characteristics in martensitic transformation (MT) are summarized. All-round analysis and research about crystallography and morphology of MT have been done based on our "displacement vector" theory. New viewpoints that the "invariant-plane-strain" criterion have no universality and that the large rotation of habit-planes takes place in {557} lath and {225} plate martensites are put forward. Thereby, the formation mode of {557} martensite is established, which is in good agreement with the experimental results. Finally, according to the self-accommodation principle between variants crystallographic calculations of twin and multi-variant martensites in shape memory alloys have been carried out. The calculation method greatly simplifies the crystallographic calculation process of phenomenological theory. And the calculated results are in good agreement with experimental ones.

  13. Crystallographically uniform arrays of ordered (In)GaN nanocolumns

    Energy Technology Data Exchange (ETDEWEB)

    Gačević, Ž., E-mail: gacevic@isom.upm.es; Bengoechea-Encabo, A.; Albert, S.; Calleja, E. [ETSIT-ISOM, Universidad Politécnica de Madrid, Avda. Complutense s/n, 28040 Madrid (Spain); Torres-Pardo, A.; González-Calbet, J. M. [Dept. Química Inorgánica, Universidad Complutense, 28040 Madrid (Spain); CEI Campus Moncloa, UCM-UPM, Madrid (Spain)

    2015-01-21

    In this work, through a comparative study of self-assembled (SA) and selective area grown (SAG) (In)GaN nanocolumn (NC) ensembles, we first give a detailed insight into improved crystallographic uniformity (homogeneity of crystallographic tilts and twists) of the latter ones. The study, performed making use of: reflective high energy electron diffraction, X-ray diffraction and scanning electron microscopy, reveals that unlike their SA counterparts, the ensembles of SAG NCs show single epitaxial relationship to both sapphire(0001) and Si(111) underlying substrates. In the second part of the article, making use of X-ray diffraction, we directly show that the selective area growth leads to improved compositional uniformity of InGaN NC ensembles. This further leads to improved spectral purity of their luminescence, as confirmed by comparative macro-photoluminescence measurements performed on SA and SAG InGaN NC ensembles. An improved crystallographic uniformity of NC ensembles facilitates their integration into optoelectronic devices, whereas their improved compositional uniformity allows for their employment in single-color optoelectronic applications.

  14. Crystallographically uniform arrays of ordered (In)GaN nanocolumns

    Science.gov (United States)

    Gačević, Ž.; Bengoechea-Encabo, A.; Albert, S.; Torres-Pardo, A.; González-Calbet, J. M.; Calleja, E.

    2015-01-01

    In this work, through a comparative study of self-assembled (SA) and selective area grown (SAG) (In)GaN nanocolumn (NC) ensembles, we first give a detailed insight into improved crystallographic uniformity (homogeneity of crystallographic tilts and twists) of the latter ones. The study, performed making use of: reflective high energy electron diffraction, X-ray diffraction and scanning electron microscopy, reveals that unlike their SA counterparts, the ensembles of SAG NCs show single epitaxial relationship to both sapphire(0001) and Si(111) underlying substrates. In the second part of the article, making use of X-ray diffraction, we directly show that the selective area growth leads to improved compositional uniformity of InGaN NC ensembles. This further leads to improved spectral purity of their luminescence, as confirmed by comparative macro-photoluminescence measurements performed on SA and SAG InGaN NC ensembles. An improved crystallographic uniformity of NC ensembles facilitates their integration into optoelectronic devices, whereas their improved compositional uniformity allows for their employment in single-color optoelectronic applications.

  15. Crystal structure of [(1,2,3,4,11,12-η)-anthracene]tris-(tri-methyl-stann-yl)cobalt(III).

    Science.gov (United States)

    Brennessel, William W; Ellis, John E

    2014-11-01

    The asymmetric unit of the title structure, [Co(η(6)-C14H10){Sn(CH3)3}3], contains two independent mol-ecules. Each anthracene ligand is η(6)-coordinating to a Co(III) cation and is nearly planar [fold angles of 5.4 (3) and 9.7 (3)°], as would be expected for its behaving almost entirely as a donor to a high-oxidation-state metal center. The slight fold in each anthracene ligand gives rise to slightly longer Co-C bond lengths to the ring junction carbon atoms than to the other four. Each Co(III) cation is further coordinated by three Sn(CH3)3 ligands, giving each mol-ecule a three-legged piano-stool geometry. In each of the two independent mol-ecules, the trio of SnMe3 ligands are modeled as disordered over two positions, rotated by approximately 30%, such that the C atoms nearly overlap. In one mol-ecule, the disorder ratio refined to 0.9365 (8):0.0635 (8), while that for the other refined to 0.9686 (8):0.0314 (8). The mol-ecules are well separated, and thus no significant inter-molecular inter-actions are observed. The compound is of inter-est as the first structure report of an η(6)-anthracene cobalt(III) complex.

  16. Independent Directors

    DEFF Research Database (Denmark)

    Ringe, Wolf-Georg

    2013-01-01

    This paper re-evaluates the corporate governance concept of ‘board independence’ against the disappointing experiences during the 2007-08 financial crisis. Independent or outside directors had long been seen as an essential tool to improve the monitoring role of the board. Yet the crisis revealed...... that they did not prevent firms' excessive risk taking; further, these directors sometimes showed serious deficits in understanding the business they were supposed to control, and remained passive in addressing structural problems. A closer look reveals that under the surface of seemingly unanimous consensus...... about board independence in Western jurisdictions, a surprising disharmony prevails about the justification, extent and purpose of independence requirements. These considerations lead me to question the benefits of the current system. Instead, this paper proposes a new, ‘functional’ concept of board...

  17. Choosing Independence

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Milo Djukanovic, Prime Minister of Montenegro, won a key referendum May 21 when voters in his tiny, mountainous nation endorsed a plan to split from Serbia and become an independent state. This marked a final step in the breakup of the former Yugoslavia formed by six republics.

  18. Crystal structure of benzyl (E)-2-(3,4-di-meth-oxy-benzyl-idene)hydrazine-1-carbodi-thio-ate.

    Science.gov (United States)

    Tan, Yew-Fung; Break, Mohammed Khaled Bin; Tahir, M Ibrahim M; Khoo, Teng-Jin

    2015-02-01

    The title compound, C17H18N2O2S2, synthesized via a condensation reaction between S-benzyl di-thio-carbazate and 3,4-di-meth-oxy-benzaldehyde, crystallized with two independent mol-ecules (A and B) in the asymmetric unit. Both mol-ecules have an L-shape but differ in the orientation of the benzyl ring with respect to the 3,4-di-meth-oxy-benzyl-idine ring, this dihedral angle is 65.59 (8)° in mol-ecule A and 73.10 (8)° in mol-ecule B. In the crystal, the A and B mol-ecules are linked via pairs of N-H⋯S hydrogen bonds, forming dimers with an R 2 (2)(8) ring motif. The dimers are linked via pairs of C-H⋯O hydrogen bonds, giving inversion dimers of dimers. These units are linked by C-H⋯π inter-actions, forming ribbons propagating in the [100] direction.

  19. Crystal structures of (2E)-1-(3-bromo-thio-phen-2-yl)-3-(2-meth-oxy-phen-yl)prop-2-en-1-one and (2E)-1-(3-bromo-thio-phen-2-yl)-3-(3,4-di-meth-oxy-phen-yl)prop-2-en-1-one.

    Science.gov (United States)

    Naik, Vasant S; Shettigar, Venkataraya; Berglin, Tyler S; Coburn, Jillian S; Jasinski, Jerry P; Yathirajan, Hemmige S

    2015-08-01

    In the mol-ecules of the title compounds, (2E)-1-(3-bromo-thio-phen-2-yl)-3-(2-meth-oxy-phen-yl)prop-2-en-1-one, C14H11BrO2S, (I), which crystallizes in the space group P-1 with four independent mol-ecules in the asymmetric unit (Z' = 8), and (2E)-1-(3-bromo-thio-phen-2-yl)-3-(3,4-di-meth-oxy-phen-yl)prop-2-en-1-one, C15H13BrO3S, (II), which crystallizes with Z' = 8 in the space group I2/a, the non-H atoms are nearly coplanar. The mol-ecules of (I) pack with inversion symmetry stacked diagonally along the a-axis direction. Weak C-H⋯Br intra-molecular inter-actions in each of the four mol-ecules in the asymmetric unit are observed. In (II), weak C-H⋯O, bifurcated three-center inter-molecular inter-actions forming dimers along with weak C-H⋯π and π-π stacking inter-actions are observed, linking the mol-ecules into sheets along [001]. A weak C-H⋯Br intra-molecular inter-action is also present. There are no classical hydrogen bonds present in either structure.

  20. (1R,4R,6S,7S)-5,5-Di-chloro-1,4,8,8-tetra-methyl-tri-cyclo-[5.4.1(1,7).0(4,6)]dodecan-12-one.

    Science.gov (United States)

    Benharref, Ahmed; El Karroumi, Jamal; Daran, Jean-Claude; Berraho, Moha

    2013-10-26

    The title compound, C16H24Cl2O, was synthesized in three steps from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from essential oil of the Atlas cedar (cedrus atlantica). The asymmetric unit contains two independent mol-ecules with similar conformations. Each mol-ecule is built up from two fused seven-membered rings and an additional three-membered ring arising from the reaction of himachalene with di-chloro-carbene. The dihedral angles between the mean planes of the two seven-membered rings are 75.03 (9) and 75.02 (9)° in the two independent mol-ecules.

  1. Crystallographic B factor of critical residues at enzyme active site

    Institute of Scientific and Technical Information of China (English)

    张海龙; 宋时英; 林政炯

    1999-01-01

    Thirty-seven sets of crystallographic enzyme data were selected from Protein Data Bank (PDB, 1995). The average temperature factors (B) of the critical residues at the active site and the whole molecule of those enzymes were calculated respectively. The statistical results showed that the critical residues at the active site of most of the enzymes had lower B factors than did the whole molecules, indicating that in the crystalline state the critical residues at the active site of the natural enzymes possess more stable conformation than do the whole molecules. The flexibility of the active site during the unfolding by denaturing was also discussed.

  2. Independent preferences

    DEFF Research Database (Denmark)

    Vind, Karl

    1991-01-01

    A simple mathematical result characterizing a subset of a product set is proved and used to obtain additive representations of preferences. The additivity consequences of independence assumptions are obtained for preferences which are not total or transitive. This means that most of the economic...... theory based on additive preferences - expected utility, discounted utility - has been generalized to preferences which are not total or transitive. Other economic applications of the theorem are given...

  3. Crystallographic Orientation Effect on Electromigration in Ni-Sn Microbump

    Science.gov (United States)

    Huang, Yi-Ting; Chen, Chih-Hao; Chakroborty, Subhendu; Wu, Albert T.

    2017-09-01

    This article addresses the reliability challenges regarding electromigration in developing three-dimensional integrated circuits (3D-ICs). The line-type sandwich structure of Ni/Sn3.5Ag(15 μm)/Ni was used to simulate microbumps to examine the reliability of electromigration in 3D-IC technology. The solder strip of Ni/Sn3.5Ag(15 μm)/Ni was stressed with a current density of 1.0 × 104 A/cm2 at 150°C. The current stressing enhanced the reaction between the solder and Ni to form Ni3Sn4, which occupied the entire joint and transformed into a Ni/Ni3Sn4/Ni structure when the solder was completely consumed. Electron backscatter diffraction was used to analyze the crystallographic characteristics of Sn and Ni3Sn4 as related to the electromigration effect. The results indicated that the crystallographic orientation of Sn plays a significant role in the Ni/Sn3.5Ag/Ni, whereas the orientation of Ni3Sn4 is the dominant factor of diffusion behavior in the Ni/Ni3Sn4/Ni.

  4. Crystallographic properties of magnetron sputtered barium ferrite films

    Energy Technology Data Exchange (ETDEWEB)

    Capraro, S. [Laboratoire DIOM, University of Saint-Etienne, 23 rue Michelon, 42023 Saint-Etienne Cedex (France)]. E-mail: stephane.capraro@univ-st-etienne.fr; Berre, M. Le [LPM, UMR 5511, INSA Lyon, 7 av. Jean Capelle, 69621 Villeurbanne Cedex (France); Chatelon, J.P. [Laboratoire DIOM, University of Saint-Etienne, 23 rue Michelon, 42023 Saint-Etienne Cedex (France); Bayard, B. [Laboratoire DIOM, University of Saint-Etienne, 23 rue Michelon, 42023 Saint-Etienne Cedex (France); Joisten, H. [CEA-LETI, 17 rue des martyrs, 38041 Grenoble Cedex (France); Canut, C. [LPMCN, University Lyon I, 43 Bvd. du 11 novembre 1918, 69622 Villerbanne, Cedex (France); Barbier, D. [LPM, UMR 5511, INSA Lyon, 7 av. Jean Capelle, 69621 Villeurbanne Cedex (France); Rousseau, J.J. [Laboratoire DIOM, University of Saint-Etienne, 23 rue Michelon, 42023 Saint-Etienne Cedex (France)

    2004-09-15

    The development of devices combining a ferrite with a semiconductor chip is a major focus of current research. Barium hexaferrite (BaFe{sub 12}O{sub 19} or BaM) thick films are deposited here using a RF magnetron sputtering system. Films are amorphous and non magnetic after deposition. Post-deposition thermal annealing is employed to make the films crystallize. The effects of the substrate, thermal annealing process, thickness, substrate temperature on crystallographic properties and stoichiometry are studied using a X-ray diffractometry (XRD) and Rutherford back-scattering (RBS). The in-depth homogeneity of Ba, Fe and O is evaluated by secondary ion mass spectroscopy (SIMS). The study shows a good crystallization of BaM films and there is a preferential orientation among the crystallographic planes (1 0 1), (2 0 0), (2 0 3), (1 0 2), (1 1 0) and (2 0 5) when BaM films are prepared at low RF power and when the substrate is heated. For several elaboration parameters, grains size is in the range of 25 and 40 nm and BaM films are stoichiometric with regard to the target stoichiometry.

  5. Crystallographic Orientation Effect on Electromigration in Ni-Sn Microbump

    Science.gov (United States)

    Huang, Yi-Ting; Chen, Chih-Hao; Chakroborty, Subhendu; Wu, Albert T.

    2017-07-01

    This article addresses the reliability challenges regarding electromigration in developing three-dimensional integrated circuits (3D-ICs). The line-type sandwich structure of Ni/Sn3.5Ag(15 μm)/Ni was used to simulate microbumps to examine the reliability of electromigration in 3D-IC technology. The solder strip of Ni/Sn3.5Ag(15 μm)/Ni was stressed with a current density of 1.0 × 104 A/cm2 at 150°C. The current stressing enhanced the reaction between the solder and Ni to form Ni3Sn4, which occupied the entire joint and transformed into a Ni/Ni3Sn4/Ni structure when the solder was completely consumed. Electron backscatter diffraction was used to analyze the crystallographic characteristics of Sn and Ni3Sn4 as related to the electromigration effect. The results indicated that the crystallographic orientation of Sn plays a significant role in the Ni/Sn3.5Ag/Ni, whereas the orientation of Ni3Sn4 is the dominant factor of diffusion behavior in the Ni/Ni3Sn4/Ni.

  6. Crystallographic alignment of high-density gallium nitride nanowire arrays.

    Science.gov (United States)

    Kuykendall, Tevye; Pauzauskie, Peter J; Zhang, Yanfeng; Goldberger, Joshua; Sirbuly, Donald; Denlinger, Jonathan; Yang, Peidong

    2004-08-01

    Single-crystalline, one-dimensional semiconductor nanostructures are considered to be one of the critical building blocks for nanoscale optoelectronics. Elucidation of the vapour-liquid-solid growth mechanism has already enabled precise control over nanowire position and size, yet to date, no reports have demonstrated the ability to choose from different crystallographic growth directions of a nanowire array. Control over the nanowire growth direction is extremely desirable, in that anisotropic parameters such as thermal and electrical conductivity, index of refraction, piezoelectric polarization, and bandgap may be used to tune the physical properties of nanowires made from a given material. Here we demonstrate the use of metal-organic chemical vapour deposition (MOCVD) and appropriate substrate selection to control the crystallographic growth directions of high-density arrays of gallium nitride nanowires with distinct geometric and physical properties. Epitaxial growth of wurtzite gallium nitride on (100) gamma-LiAlO(2) and (111) MgO single-crystal substrates resulted in the selective growth of nanowires in the orthogonal [1\\[Evec]0] and [001] directions, exhibiting triangular and hexagonal cross-sections and drastically different optical emission. The MOCVD process is entirely compatible with the current GaN thin-film technology, which would lead to easy scale-up and device integration.

  7. Diffusion-equation method for crystallographic figure of merits.

    Science.gov (United States)

    Markvardsen, Anders J; David, William I F

    2010-09-01

    Global optimization methods play a significant role in crystallography, particularly in structure solution from powder diffraction data. This paper presents the mathematical foundations for a diffusion-equation-based optimization method. The diffusion equation is best known for describing how heat propagates in matter. However, it has also attracted considerable attention as the basis for global optimization of a multimodal function [Piela et al. (1989). J. Phys. Chem. 93, 3339-3346]. The method relies heavily on available analytical solutions for the diffusion equation. Here it is shown that such solutions can be obtained for two important crystallographic figure-of-merit (FOM) functions that fully account for space-group symmetry and allow the diffusion-equation solution to vary depending on whether atomic coordinates are fixed or not. The resulting expression is computationally efficient, taking the same order of floating-point operations to evaluate as the starting FOM function measured in terms of the number of atoms in the asymmetric unit. This opens the possibility of implementing diffusion-equation methods for crystallographic global optimization algorithms such as structure determination from powder diffraction data.

  8. Crystallographic studies of gas sorption in metal–organic frameworks

    Science.gov (United States)

    Carrington, Elliot J.; Vitórica-Yrezábal, Iñigo J.; Brammer, Lee

    2014-01-01

    Metal–organic frameworks (MOFs) are a class of porous crystalline materials of modular design. One of the primary applications of these materials is in the adsorption and separation of gases, with potential benefits to the energy, transport and medical sectors. In situ crystallography of MOFs under gas atmospheres has enabled the behaviour of the frameworks under gas loading to be investigated and has established the precise location of adsorbed gas molecules in a significant number of MOFs. This article reviews progress in such crystallographic studies, which has taken place over the past decade, but has its origins in earlier studies of zeolites, clathrates etc. The review considers studies by single-crystal or powder diffraction using either X-rays or neutrons. Features of MOFs that strongly affect gas sorption behaviour are discussed in the context of in situ crystallographic studies, specifically framework flexibility, and the presence of (organic) functional groups and unsaturated (open) metal sites within pores that can form specific interactions with gas molecules. PMID:24892587

  9. (1S,2R,7R,8S,10R)-9,9-Di-bromo-2,6,6,10-tetra-methyl-1α,2α-ep-oxy-tri-cyclo-[5.5.0.0(8,10)]dodeca-ne.

    Science.gov (United States)

    Benharref, Ahmed; El Karroumi, Jamal; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

    2013-01-01

    The title compound, C16H24Br2O, was synthesized from the reaction of β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from Atlas cedar (Cedrus atlantica) essential oil, after reaction with di-bromo-carbene. The asymmetric unit contains two independent mol-ecules with similar conformations. Each mol-ecule is built up from fused six-and seven-membered rings and two three-membered rings. In both mol-ecules, the six-membered ring has an envelope conformation with the flap provided by the C atom of the ep-oxy ring, whereas the seven-membered ring displays a chair conformation. The crystal packing is governed only by van der Waals inter-actions. The absolute configuration was established from anomalous dispersion effects.

  10. (1S,3S,8R,9S,11R)-10,10-Di-bromo-3,7,7,11-tetra-methyl-tetra-cyclo-[6.5.0.0(1,3).0(9,11)]trideca-ne.

    Science.gov (United States)

    Benharref, Ahmed; El Karroumi, Jamal; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

    2013-01-01

    The title compound, C17H26Br2, was synthesized from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The asymmetric unit contains two independent mol-ecules with similar conformations. Each mol-ecule is built up from fused six- and seven-membered rings and two appended three-membered rings. In both mol-ecules, the six-membered ring has a screw boat conformation, whereas the seven-membered ring displays a boat conformation. No specific inter-molecular inter-actions were discerned in the crystal packing.

  11. (1S,3S,8R,9S,11R)-10,10-Di-chloro-3,7,7,11-tetra-methyl-tetra-cyclo[6.5.0.0(1,3).0(9,11)]trideca-ne.

    Science.gov (United States)

    Benharref, Ahmed; Ourhriss, Najia; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

    2013-06-01

    The title compound, C17H26Cl2, was synthesized from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The asymmetric unit contains two independent mol-ecules with similar conformations. Each mol-ecule is built up from fused six- and seven-membered rings and two three-membered rings from the reaction of β-himachalene with di-chloro-carbene. In both mol-ecules, the six-membered ring has a half-chair conformation, whereas the seven-membered ring displays a boat conformation. The absolute configuration was established from anomalous dispersion effects.

  12. (1S,3R,8R,9S,11R)-10,10-Di-bromo-2,2-di-chloro-3,7,7,11-tetra-methyl-tetra-cyclo-[6.5.0.0(1,3).0(9,11)]trideca-ne.

    Science.gov (United States)

    Oukhrib, Abdelouahd; Benharref, Ahmed; Saadi, Mohamed; Berraho, Moha; El Ammari, Lahcen

    2013-05-01

    The title compound, C17H24Br2Cl2, was synthesized from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from the essential oil of the Atlas cedar (Cedrus Atlantica). The asymmetric unit contains two independent mol-ecules. Each mol-ecule is built up from fused six-, seven- and two three-membered rings. In both mol-ecules, the six-membered ring has a half-chair conformation, whereas the seven-membered ring displays a boat conformation. No specific inter-molecular inter-actions are noted in the crystal packing.

  13. Crystal structure of 2,2-dimethyl-N-(5-methyl-pyridin-2-yl)propanamide.

    Science.gov (United States)

    El-Hiti, Gamal A; Smith, Keith; Hegazy, Amany S; Alanazi, Saud A; Kariuki, Benson M

    2015-06-01

    There are two mol-ecules in the asymmetric unit of the title compound, C11H16N2O. The pyridine rings and amide groups overlap almost perfectly (r.m.s. overlay fit = 0.053 Å), but the tertiary butyl groups have different orientations: in one mol-ecule, one of the methyl C atoms is syn to the amide O atom [O-C-C-C = -0.8 (3)°] and in the other the equivalent torsion angle is 31.0 (2)°. In the crystal, the two independent mol-ecules are linked by a pair of N-H⋯N hydrogen bonds in the form of an R 2 (2)(8) loop to form a dimer. A C-H⋯O inter-action connects the dimers into [100] chains.

  14. (1S,2R,8R)-2,2-Dichloro-3,7,7,10-tetra-methyltricyclo-[6.4.0.0]dodec-10-en-9-one.

    Science.gov (United States)

    Benharref, Ahmed; El Ammari, Lahcen; Berraho, Moha

    2010-10-23

    The title compound, C(16)H(22)Cl(2)O, was synthesized from β-himachalene, which was isolated from essential oil of the Atlas cedar (cedrus atlantica). The asymmetric unit contains two independent mol-ecules, in each of which the six-membered ring shows a half-chair conformation, whereas the seven-membered ring displays a boat conformation. The dihedral angle between the two rings is slightly different in the two mol-ecules [63.22 (13) and 61.81 (14)°].

  15. Crystallographic shear mechanisms in Rh one-dimensional oxides

    Science.gov (United States)

    Hernando, María; Boulahya, Khalid; Parras, Marina; González-Calbet, José M.

    2005-02-01

    Electron diffraction and high resolution electron microscopy have been used to characterize two new one-dimensional superstructures in the A sbnd Rh sbnd O system (A = Ca, Sr) related to the 2H-ABO 3-type. They are formed by the intergrowth of n A 3A'BO 6 blocks, showing the Sr 4RhO 6-type, with A 12A' 2B 8O 30 blocks, constituted by two A 3O 9 and two A 3A'O 6 layers alternating in the stacking sequence 1:1, leading to the A 27A' 7B 13O 60 ( n=5) and A 30A' 8B 14O 66 ( n=6) compositions. A crystallographic shear mechanism is proposed to describe the structural relationship between Sr 4RhO 6 (A 3A'BO 6-type) and the new superstructures.

  16. 3D characterization of crystallographic orientation in polycrystals via EBSD

    Institute of Scientific and Technical Information of China (English)

    Stefan ZAEFFERER; Stuart I. WRIGHT

    2007-01-01

    Electron Backscatter Diffraction (EBSD) has been used in conjunction with a Scanning Electron Microscope (SEM) combined with a focused ion beam (FIB) instrument to obtain three dimensional (3D) high resolution characterizations of crystalline microstructures. This work reports on continued development that has proceeded on this technique. The technique is based on automated in-situ serial sectioning using the FIB and characterization of the sections using automated EBSD or orientation imaging microscopy (OIM). The technique extends the powerful features of two dimensional OIM into the third spatial dimension. This allows additional descriptive microstructural parameters to be obtained, for example the morphology and the crystallographic indices of interface planes. This paper provides an overview of the technique and shows results from two different samples: pearlite colonies in a high carbon steel and twin related grain triplets in a NiCo thin film.

  17. Crystallographic texturing in Nb3Sn multifilamentary superconducting composites

    Science.gov (United States)

    Cogan, Stuart F.; Rose, Robert M.

    1980-03-01

    Crystallographic texturing in Nb3Sn composites, fabricated by both the external diffusion and the commercial bronze processes, has been investigated. In the external-diffusion-processed composite the as-drawn texture of the copper matrix contained ca. 55% and 45% ; after recrystallization at 650 °C for 16 h this changed to 70% and 30% . Tin plating and reaction heat treatment for 40 h at 650 °C eliminated most of the texturing. In a commercial bronze-processed composite a or texture was obtained in the as-drawn bronze matrix, and after a reaction heat treatment at 700 °C for 30 h a diffuse texture was developed. In both composites the Nb3Sn reaction layer exhibited no preferred orientation.

  18. Ocean acidification reduces the crystallographic control in juvenile mussel shells.

    Science.gov (United States)

    Fitzer, Susan C; Cusack, Maggie; Phoenix, Vernon R; Kamenos, Nicholas A

    2014-10-01

    Global climate change threatens the oceans as anthropogenic carbon dioxide causes ocean acidification and reduced carbonate saturation. Future projections indicate under saturation of aragonite, and potentially calcite, in the oceans by 2100. Calcifying organisms are those most at risk from such ocean acidification, as carbonate is vital in the biomineralisation of their calcium carbonate protective shells. This study highlights the importance of multi-generational studies to investigate how marine organisms can potentially adapt to future projected global climate change. Mytilus edulis is an economically important marine calcifier vulnerable to decreasing carbonate saturation as their shells comprise two calcium carbonate polymorphs: aragonite and calcite. M. edulis specimens were cultured under current and projected pCO2 (380, 550, 750 and 1000μatm), following 6months of experimental culture, adults produced second generation juvenile mussels. Juvenile mussel shells were examined for structural and crystallographic orientation of aragonite and calcite. At 1000μatm pCO2, juvenile mussels spawned and grown under this high pCO2 do not produce aragonite which is more vulnerable to carbonate under-saturation than calcite. Calcite and aragonite were produced at 380, 550 and 750μatm pCO2. Electron back scatter diffraction analyses reveal less constraint in crystallographic orientation with increased pCO2. Shell formation is maintained, although the nacre crystals appear corroded and crystals are not so closely layered together. The differences in ultrastructure and crystallography in shells formed by juveniles spawned from adults in high pCO2 conditions may prove instrumental in their ability to survive ocean acidification. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Use of multiple picosecond high-mass molecular dynamics simulations to predict crystallographic B-factors of folded globular proteins.

    Science.gov (United States)

    Pang, Yuan-Ping

    2016-09-01

    Predicting crystallographic B-factors of a protein from a conventional molecular dynamics simulation is challenging, in part because the B-factors calculated through sampling the atomic positional fluctuations in a picosecond molecular dynamics simulation are unreliable, and the sampling of a longer simulation yields overly large root mean square deviations between calculated and experimental B-factors. This article reports improved B-factor prediction achieved by sampling the atomic positional fluctuations in multiple picosecond molecular dynamics simulations that use uniformly increased atomic masses by 100-fold to increase time resolution. Using the third immunoglobulin-binding domain of protein G, bovine pancreatic trypsin inhibitor, ubiquitin, and lysozyme as model systems, the B-factor root mean square deviations (mean ± standard error) of these proteins were 3.1 ± 0.2-9 ± 1 Å(2) for Cα and 7.3 ± 0.9-9.6 ± 0.2 Å(2) for Cγ, when the sampling was done for each of these proteins over 20 distinct, independent, and 50-picosecond high-mass molecular dynamics simulations with AMBER forcefield FF12MC or FF14SB. These results suggest that sampling the atomic positional fluctuations in multiple picosecond high-mass molecular dynamics simulations may be conducive to a priori prediction of crystallographic B-factors of a folded globular protein.

  20. Poly[tetra-aqua-di-μ(4)-malonato-barium(II)cadmium(II)].

    Science.gov (United States)

    Guo, Ming-Lin; Gao, Wen-Jun; Luo, Cong-Cong; Liu, Long

    2010-12-04

    In the title complex, [BaCd(C(3)H(2)O(4))(2)(H(2)O)(4)](n), the Ba(II) atoms, located on crystallographic twofold axes, adopt slightly distorted square-anti-prismatic coordination geometries, while the Cd(II) atoms, which lie on crystallographic centres of symmetry, have a distorted octa-hedral coordination. Each malonate dianion binds two different Cd(II) atoms and two different Ba(II) atoms. This connectivity generates alternating layers along [100] in the structure, with one type containing Cd(II) cations and malonate dianions, while the other is primarily composed of Ba(II) ions and coordinated water mol-ecules. The water mol-ecules also participate in extensive O-H⋯O hydrogen bonding.

  1. An introduction to the tools hosted in the Bilbao Crystallographic Server

    Directory of Open Access Journals (Sweden)

    Aroyo M.I.

    2012-03-01

    Full Text Available The programs hosted in the Bilbao Crystallographic Server (http://www.cryst.ehu.es are briefly explained along with worked examples on various cases related to different fields of applications. It is our aim to have this text acting as a primer on the various usage of the crystallographic tools in conjunction with each other due to the modular structure of the server. For this reason, diverse topics such as crystallographic groups and their subgroups, pseudosymmetry, extinction conditions, k-vectors and irreducible representations have been discussed in the context.

  2. Nanocrystalline materials: recent advances in crystallographic characterization techniques

    Directory of Open Access Journals (Sweden)

    Emilie Ringe

    2014-11-01

    Full Text Available Most properties of nanocrystalline materials are shape-dependent, providing their exquisite tunability in optical, mechanical, electronic and catalytic properties. An example of the former is localized surface plasmon resonance (LSPR, the coherent oscillation of conduction electrons in metals that can be excited by the electric field of light; this resonance frequency is highly dependent on both the size and shape of a nanocrystal. An example of the latter is the marked difference in catalytic activity observed for different Pd nanoparticles. Such examples highlight the importance of particle shape in nanocrystalline materials and their practical applications. However, one may ask `how are nanoshapes created?', `how does the shape relate to the atomic packing and crystallography of the material?', `how can we control and characterize the external shape and crystal structure of such small nanocrystals?'. This feature article aims to give the reader an overview of important techniques, concepts and recent advances related to these questions. Nucleation, growth and how seed crystallography influences the final synthesis product are discussed, followed by shape prediction models based on seed crystallography and thermodynamic or kinetic parameters. The crystallographic implications of epitaxy and orientation in multilayered, core-shell nanoparticles are overviewed, and, finally, the development and implications of novel, spatially resolved analysis tools are discussed.

  3. Pulsed neutron spectroscopic imaging for crystallographic texture and microstructure

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Hirotaka, E-mail: hakuryu@eng.hokudai.ac.jp [Graduate School of Engineering, Hokkaido University, Kita-13 Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Kamiyama, Takashi [Graduate School of Engineering, Hokkaido University, Kita-13 Nishi-8, Kita-ku, Sapporo 060-8628 (Japan); Iwase, Kenji; Ishigaki, Toru [Frontier Research Center for Applied Atomic Sciences, Ibaraki University, Ibaraki 319-1106 (Japan); Kiyanagi, Yoshiaki [Graduate School of Engineering, Hokkaido University, Kita-13 Nishi-8, Kita-ku, Sapporo 060-8628 (Japan)

    2011-09-21

    A time-of-flight (TOF) spectroscopic neutron imaging at a pulsed neutron source is expected to be a new material analysis tool because this method can non-destructively investigate the spatial dependence of the crystallographic and metallographic information in a bulk material. For quantitative evaluation of such information, a spectral analysis code for the transmission data is necessary. Therefore, we have developed a Rietveld-like analysis code, RITS. Furthermore, we have applied the RITS code to evaluation of the position dependence of the crystal orientation anisotropy, the preferred orientation and the crystallite size of a welded {alpha}-iron plate, and we successfully obtained the information on the texture and the microstructure. However, the reliability of the values given by the RITS code has not been evaluated yet in detail. For this reason, we compared the parameters provided by the RITS code with the parameters obtained by the neutron TOF powder diffractometry and its Rietveld analysis. Both the RITS code and the Rietveld analysis software indicated values close to each other, but there were systematic differences on the preferred orientation and the crystallite size.

  4. Cassia grandis Linn. f. seed galactomannan: structural and crystallographical studies.

    Science.gov (United States)

    Joshi, Harsha; Kapoor, Virendra P

    2003-09-01

    Cassia grandis is a small or medium sized tree, found in abundance throughout India. The seeds contain about 50% endosperm gum and possess the characteristics of becoming a potential source of seed gum. The purified polysaccharide has been characterized as a pure galactomannan having a mannose-galactose ratio of 3.15; molecular weight (Mw) 80,200; polydispersity (Mw/Mn), 1.35 and intrinsic viscosity [eta], 848 mL/g. Methylation, periodate oxidation, Smith degradation and 13C NMR studies confirm that the polysaccharide has the basic structure of legume galactomannans consisting of a beta-(1-->4)-linked main mannan backbone to which galactose units are attached at O-6. The orthorhombic lattice constants of the hydrated gum are as follows: a=9.00, b=24.81, c=10.30 A. The crystallographic data establish that the probable space group symmetry of the unit cell is P2(1)2(1)2. The results are in contradiction to earlier reports (Indian J. Chem. 16B (1978) 966; J. Indian Chem. Soc. 55 (1978) 1216) in which a non-galactomannan polysaccharide structure has been assigned having a main chain of (1-->4)-linked galactose and mannose units in the molar ratio 6:3, where 50% of the galactose units branched with two galactose and one mannose through 1-->3 linkage.

  5. Crystallographic analysis of amorphization caused by ion irradiation

    CERN Document Server

    Nakagawa, S T; Ono, T; Hada, Y; Betz, G

    2003-01-01

    Ion irradiation often causes amorphization in a crystal. We have presented a new crystallographic analysis that defines a new type of order parameter, which we call pixel mapping (PM). PM can describe algebraically to what extent and how the crystallinity has changed under ion bombardment. In other words, PM describes the long-range-order (LRO) interactions, based on the crystallography. PM can be effectively used, when it is incorporated in a classical molecular dynamics (MD) calculation. In the case of B ions implanted into a Si crystal, we observed crystal to amorphous (CA) transitions under energetic ion bombardment at low temperature. The PM profiling was more effective to reveal the CA transition than other atomistic methods of analyses as radial distribution function g(r) or vacancy mapping N sub v. PM could distinguish between perfect crystalline states, transition states, and random states. Moreover, PM revealed that the lattice reaction was cooperative even in a mesoscopic volume, e.g. in a cube of ...

  6. Crystallographic Orientation of Cuttlebone Shield Determined by Electron Backscatter Diffraction

    Science.gov (United States)

    Cusack, Maggie; Chung, Peter

    2014-01-01

    In common with many cephalopod mollusks, cuttlefish produce an internal biomineral buoyancy device. This cuttlebone is analogous to a surf board in shape and structure, providing rigidity and a means of controlling buoyancy. The cuttlebone is composed of calcium carbonate in the form of aragonite and comprises an upper dorsal shield and a lower lamellar matrix. The lamellar matrix comprises layers of chambers with highly corrugated walls. The dorsal shield comprises bundles of aragonite needles stacked on top of each other. Electron backscatter diffraction analyses of the dorsal shield reveal that the c-axis of aragonite is parallel with the long axis of the needles in the bundles such that any spread in crystallographic orientation is consistent with the spread in orientation of the fibers as they radiate to form the overall structure of the dorsal shield. This arrangement of c-axis coincident with the long axis of the biomineral structure is similar to the arrangement in corals and in contrast to the situation in the molluskan aragonite nacre of brachiopod calcite where the c-axis is perpendicular to the aragonite tablet or calcite fiber, respectively.

  7. Nanocrystalline materials: recent advances in crystallographic characterization techniques.

    Science.gov (United States)

    Ringe, Emilie

    2014-11-01

    Most properties of nanocrystalline materials are shape-dependent, providing their exquisite tunability in optical, mechanical, electronic and catalytic properties. An example of the former is localized surface plasmon resonance (LSPR), the coherent oscillation of conduction electrons in metals that can be excited by the electric field of light; this resonance frequency is highly dependent on both the size and shape of a nanocrystal. An example of the latter is the marked difference in catalytic activity observed for different Pd nanoparticles. Such examples highlight the importance of particle shape in nanocrystalline materials and their practical applications. However, one may ask 'how are nanoshapes created?', 'how does the shape relate to the atomic packing and crystallography of the material?', 'how can we control and characterize the external shape and crystal structure of such small nanocrystals?'. This feature article aims to give the reader an overview of important techniques, concepts and recent advances related to these questions. Nucleation, growth and how seed crystallography influences the final synthesis product are discussed, followed by shape prediction models based on seed crystallography and thermodynamic or kinetic parameters. The crystallographic implications of epitaxy and orientation in multilayered, core-shell nanoparticles are overviewed, and, finally, the development and implications of novel, spatially resolved analysis tools are discussed.

  8. Crystallization and preliminary crystallographic analysis of recombinant human galectin-1

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Stacy A. [Institute for Glycomics, Gold Coast Campus, Griffith University, Queensland 4222 (Australia); Scott, Ken [School of Biological Sciences, University of Auckland, Auckland (New Zealand); Blanchard, Helen, E-mail: h.blanchard@griffith.edu.au [Institute for Glycomics, Gold Coast Campus, Griffith University, Queensland 4222 (Australia)

    2007-11-01

    Human galectin-1 has been cloned, expressed in E. coli, purified and crystallized in the presence of both lactose (ligand) and β-mercaptoethanol under six different conditions. The X-ray diffraction data obtained have enabled the assignment of unit-cell parameters for two novel crystal forms of human galectin-1. Galectin-1 is considered to be a regulator protein as it is ubiquitously expressed throughout the adult body and is responsible for a broad range of cellular regulatory functions. Interest in galectin-1 from a drug-design perspective is founded on evidence of its overexpression by many cancers and its immunomodulatory properties. The development of galectin-1-specific inhibitors is a rational approach to the fight against cancer because although galectin-1 induces a plethora of effects, null mice appear normal. X-ray crystallographic structure determination will aid the structure-based design of galectin-1 inhibitors. Here, the crystallization and preliminary diffraction analysis of human galectin-1 crystals generated under six different conditions is reported. X-ray diffraction data enabled the assignment of unit-cell parameters for crystals grown under two conditions, one belongs to a tetragonal crystal system and the other was determined as monoclinic P2{sub 1}, representing two new crystal forms of human galectin-1.

  9. Phormidium phycoerythrin forms hexamers in crystals: a crystallographic study.

    Science.gov (United States)

    Sonani, Ravi Raghav; Sharma, Mahima; Gupta, Gagan Deep; Kumar, Vinay; Madamwar, Datta

    2015-08-01

    The crystallographic analysis of a marine cyanobacterium (Phormidium sp. A09DM) phycoerythrin (PE) that shows distinct sequence features compared with known PE structures from cyanobacteria and red algae is reported. Phormidium PE was crystallized using the sitting-drop vapour-diffusion method with ammonium sulfate as a precipitant. Diffraction data were collected on the protein crystallography beamline at the Indus-2 synchrotron. The crystals diffracted to about 2.1 Å resolution at 100 K. The crystals, with an apparent hexagonal morphology, belonged to space group P1, with unit-cell parameters a = 108.3, b = 108.4 Å, c = 116.6 Å, α = 78.94, β = 82.50, γ = 60.34°. The molecular-replacement solution confirmed the presence of 12 αβ monomers in the P1 cell. The Phormidium PE elutes as an (αβ)3 trimer of αβ monomers from a molecular-sieve column and exists as [(αβ)3]2 hexamers in the crystal lattice. Unlike red algal PE proteins, the hexamers of Phormidium PE do not form higher-order structures in the crystals. The existence of only one characteristic visual absorption band at 564 nm suggests the presence of phycoerythrobilin chromophores, and the absence of any other types of bilins, in the Phormidium PE assembly.

  10. Nanocrystalline materials: recent advances in crystallographic characterization techniques

    Science.gov (United States)

    Ringe, Emilie

    2014-01-01

    Most properties of nanocrystalline materials are shape-dependent, providing their exquisite tunability in optical, mechanical, electronic and catalytic properties. An example of the former is localized surface plasmon resonance (LSPR), the coherent oscillation of conduction electrons in metals that can be excited by the electric field of light; this resonance frequency is highly dependent on both the size and shape of a nanocrystal. An example of the latter is the marked difference in catalytic activity observed for different Pd nanoparticles. Such examples highlight the importance of particle shape in nanocrystalline materials and their practical applications. However, one may ask ‘how are nanoshapes created?’, ‘how does the shape relate to the atomic packing and crystallography of the material?’, ‘how can we control and characterize the external shape and crystal structure of such small nanocrystals?’. This feature article aims to give the reader an overview of important techniques, concepts and recent advances related to these questions. Nucleation, growth and how seed crystallography influences the final synthesis product are discussed, followed by shape prediction models based on seed crystallography and thermodynamic or kinetic parameters. The crystallographic implications of epitaxy and orientation in multilayered, core-shell nanoparticles are overviewed, and, finally, the development and implications of novel, spatially resolved analysis tools are discussed. PMID:25485133

  11. Di-aqua-tetra-kis-(1H-imidazole-κN (3))magnesium dichloride.

    Science.gov (United States)

    Kayalvizhi, M; Vasuki, G; Kaabi, Kamel; Ben Nasr, Cherif

    2013-01-01

    In the title compound, [Mg(C3H3N2)4(H2O)2]Cl2, the Mg(II) cation lies on a crystallographic inversion centre and is coordinated by two water mol-ecules and four N-atom donors from monodentate imidazole ligands, giving a slightly distorted octa-hedral stereochemistry. In the crystal, water O-H⋯Cl and imidazole N-H⋯Cl hydrogen bonds give rise to a three-dimensional structure.

  12. Variations in Reactivity on Different Crystallographic Orientations of Cerium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Mullins, David R [ORNL; Albrecht, Peter M [ORNL; Calaza, Florencia C [ORNL

    2013-01-01

    Cerium oxide is a principal component in many heterogeneous catalytic processes. One of its key characteristics is the ability to provide or remove oxygen in chemical reactions. The different crystallographic faces of ceria present significantly different surface structures and compositions that may alter the catalytic reactivity. The structure and composition determine the number of coordination vacancies surrounding surface atoms, the availability of adsorption sites, the spacing between adsorption sites and the ability to remove O from the surface. To investigate the role of surface orientation on reactivity, CeO2 films were grown with two different orientations. CeO2(100) films were grown ex situ by pulsed laser deposition on Nb-doped SrTiO3(100). CeO2(111) films were grown in situ by thermal deposition of Ce metal onto Ru(0001) in an oxygen atmosphere. The chemical reactivity was characterized by the adsorption and decomposition of various molecules such as alcohols, aldehydes and organic acids. In general the CeO2(100) surface was found to be more active, i.e. molecules adsorbed more readily and reacted to form new products, especially on a fully oxidized substrate. However the CeO2(100) surface was less selective with a greater propensity to produce CO, CO2 and water as products. The differences in chemical reactivity are discussed in light of possible structural terminations of the two surfaces. Recently nanocubes and nano-octahedra have been synthesized that display CeO2(100) and CeO2(111) faces, respectively. These nanoparticles enable us to correlate reactions on high surface area model catalysts at atmospheric pressure with model single crystal films in a UHV environment.

  13. Shape and crystallographic orientation of nanodiamonds for quantum sensing.

    Science.gov (United States)

    Ong, S Y; Chipaux, M; Nagl, A; Schirhagl, R

    2017-01-23

    Nanodiamonds with dimensions down to a few tens of nanometers containing nitrogen-vacancy (NV) color centers have revealed their potential as powerful and versatile quantum sensors with a unique combination of spatial resolution and sensitivity. The NV centers allow transducing physical properties, such as strain, temperature, and electric or magnetic field, to an optical transition that can be detected in the single photon range. For example, this makes it possible to sense a single electron spin or a few nuclear spins by detecting their magnetic resonance. The location and orientation of these defects with respect to the diamond surface play a crucial role in interpreting the data and predicting their sensitivities. Despite its relevance, the geometry of these nanodiamonds has never been thoroughly investigated. Without accurate data, spherical models have been applied to interpret or predict results in the past. With the use of High Resolution Transmission Electron Microscopy (HR-TEM), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM), we investigated nanodiamonds with an average hydrodynamic diameter of 25 nm (the most common type for quantum sensing) and found a flake-like geometry, with 23.2 nm and 4.5 nm being the average lateral and vertical dimensions. We have also found evidence for a preferred crystallographic orientation of the main facet in the (110) direction. Furthermore, we discuss the consequences of this difference in geometry on diamond-based applications. Shape not only influences the creation efficiency of nitrogen-vacancy centers and their quantum coherence properties (and thus sensing performance), but also the optical properties of the nanodiamonds, their interaction with living cells, and their surface chemistry.

  14. Crystallographic control on the substructure of nacre tablets.

    Science.gov (United States)

    Checa, Antonio G; Mutvei, Harry; Osuna-Mascaró, Antonio J; Bonarski, Jan T; Faryna, Marek; Berent, Katarzyna; Pina, Carlos M; Rousseau, Marthe; Macías-Sánchez, Elena

    2013-09-01

    Nacre tablets of mollusks develop two kinds of features when either the calcium carbonate or the organic portions are removed: (1) parallel lineations (vermiculations) formed by elongated carbonate rods, and (2) hourglass patterns, which appear in high relief when etched or in low relief if bleached. In untreated tablets, SEM and AFM data show that vermiculations correspond to aligned and fused aragonite nanogloblules, which are partly surrounded by thin organic pellicles. EBSD mapping of the surfaces of tablets indicates that the vermiculations are invariably parallel to the crystallographic a-axis of aragonite and that the triangles are aligned with the b-axis and correspond to the advance of the {010} faces during the growth of the tablet. According to our interpretation, the vermiculations appear because organic molecules during growth are expelled from the a-axis, where the Ca-CO3 bonds are the shortest. In this way, the subunits forming nacre merge uninterruptedly, forming chains parallel to the a-axis, whereas the organic molecules are expelled to the sides of these chains. Hourglass patterns would be produced by preferential adsorption of organic molecules along the {010}, as compared to the {100} faces. A model is presented for the nanostructure of nacre tablets. SEM and EBSD data also show the existence within the tablets of nanocrystalline units, which are twinned on {110} with the rest of the tablet. Our study shows that the growth dynamics of nacre tablets (and bioaragonite in general) results from the interaction at two different and mutually related levels: tablets and nanogranules.

  15. Energetic, crystallographic and diffusion characteristics of hydrogen isotopes in iron

    Energy Technology Data Exchange (ETDEWEB)

    Sivak, A.B., E-mail: sivak_ab@nrcki.ru [National Research Centre “Kurchatov Institute”, 1, Akademika Kurchatova pl., Moscow 123182 (Russian Federation); National Research Tomsk State University, 36, Lenina pr., Tomsk 634050 (Russian Federation); Sivak, P.A., E-mail: sivak_pa@nrcki.ru [National Research Centre “Kurchatov Institute”, 1, Akademika Kurchatova pl., Moscow 123182 (Russian Federation); Romanov, V.A., E-mail: romanov-ippe@mail.ru [National Research Tomsk State University, 36, Lenina pr., Tomsk 634050 (Russian Federation); A.I. Leypunski Institute of Physics and Power Engineering (IPPE), 1, Bondarenko pl., Obninsk, Kaluga reg. 249033 (Russian Federation); Chernov, V.M., E-mail: vmchernov@bochvar.ru [National Research Tomsk State University, 36, Lenina pr., Tomsk 634050 (Russian Federation); A.A. Bochvar High-technology Research Institute of Inorganic Materials (JSC “VNIINM”), 5-a, Rogova ul., PoB 369, Moscow 123098 (Russian Federation); National Research Nuclear University “MEPhI”, 31, Kashirskoye sh., Moscow 115409 (Russian Federation)

    2015-06-15

    Highlights: • H isotopes properties in Fe were calculated by molecular statics and dynamics methods. • The binding energies of complexes “H atoms – self-defects” were calculated. • Temperature dependencies of H isotopes diffusivities have parabolic form at T > 250 K. • There is a good agreement between MD and experimental data for protium diffusivity. • H isotopes diffusivities are within 10% at 293 K. Isotope effect increases with temperature. - Abstract: Energetic, crystallographic and diffusion characteristics of various interstitial configurations of H atoms and their complexes with self-point defects (SIA – self-interstitial atom, V – vacancy) in bcc iron have been calculated by molecular statics and molecular dynamics using Fe–H interatomic interaction potential developed by Ramasubramaniam et al. (2009) and modified by the authors of the present work and Fe–Fe matrix potential M07 developed by Malerba et al. (2010). The most energetically favorable configuration of an interstitial H atom is tetrahedral configuration. The energy barrier for H atom migration is 0.04 eV. The highest binding energy of all the considered complexes “vacancy – H atom” and “SIA – H atom” is 0.54 and 0.15 eV, respectively. The binding energy of H atom with edge dislocations in slip systems 〈1 1 1〉{1 1 0}, 〈1 1 1〉{1 1 2}, 〈1 0 0〉{1 0 0}, 〈1 0 0〉{1 1 0} is 0.32, 0.30, 0.45, 0.54 eV, respectively. The binding energy of H atom in VH{sub n} complexes (n = 1 … 15) decreases from 0.54 to 0.35 eV with increasing of n from 1 to 6. At n > 6, it decreases to ∼0.1 eV. The temperature dependences of hydrogen isotopes (P, D, T) diffusivities have been calculated for the temperature range 70–1800 K. Arrhenius-type dependencies describe the calculated data at temperatures T < 100 K. At T > 250 K, the temperature dependencies of the diffusivities D{sup P}, D{sup D}, D{sup T} have a parabolic form. The diffusivities of H isotopes are within 10

  16. Crystallographic transformation of limestone during calcination under CO2.

    Science.gov (United States)

    Valverde, Jose Manuel; Medina, Santiago

    2015-09-14

    The calcination reaction of limestone (CaCO3) to yield lime (CaO) is at the heart of many industrial applications as well as natural processes. In the recently emerged calcium-looping technology, CO2 capture is accomplished by the carbonation of CaO in a gas-solid reactor (carbonator). CaO is derived by the calcination of limestone in a calciner reactor under necessarily high CO2 partial pressure and high temperature. In situ X-ray diffraction (XRD) has been employed in this work to gain further insight into the crystallographic transformation that takes place during the calcination of limestone under CO2, at partial pressures (P) close to the equilibrium pressure (Peq) and at high temperature. Calcination under these conditions becomes extremely slow. The in situ XRD analysis presented here suggests the presence of an intermediate metastable CaO* phase stemming from the parent CaCO3 structure. According to the reaction mechanism proposed elsewhere, the exothermicity of the CaO* → CaO transformation and high values of P/Peq inhibit the nucleation of CaO at high temperatures. The wt% of CaO* remains at a relatively high level during slow calcination. Two diverse stages have been identified in the evolution of CaO crystallite size, L. Initially, L increases with CaCO3 conversion, following a logarithmic law. Slow calcination allows the crystallite size to grow up from a few nanometers at nucleation up to around 100 nm near the end of conversion. Otherwise, quick calcination at relatively lower CO2 concentrations limits CaO crystallite growth. Once calcination reaches an advanced state, the presence of CaO* drops to zero and the rate of increase of the CaO crystallite size is significantly hindered. Arguably, the first stage in CaO crystallite growth is driven by aggregation of the metastable CaO* nanocrystals, due to surface attractive forces, whereas the second one is consistent with sintering of the aggregated CaO crystals, and persists with time after full

  17. A log-likelihood-gain intensity target for crystallographic phasing that accounts for experimental error.

    Science.gov (United States)

    Read, Randy J; McCoy, Airlie J

    2016-03-01

    The crystallographic diffraction experiment measures Bragg intensities; crystallographic electron-density maps and other crystallographic calculations in phasing require structure-factor amplitudes. If data were measured with no errors, the structure-factor amplitudes would be trivially proportional to the square roots of the intensities. When the experimental errors are large, and especially when random errors yield negative net intensities, the conversion of intensities and their error estimates into amplitudes and associated error estimates becomes nontrivial. Although this problem has been addressed intermittently in the history of crystallographic phasing, current approaches to accounting for experimental errors in macromolecular crystallography have numerous significant defects. These have been addressed with the formulation of LLGI, a log-likelihood-gain function in terms of the Bragg intensities and their associated experimental error estimates. LLGI has the correct asymptotic behaviour for data with large experimental error, appropriately downweighting these reflections without introducing bias. LLGI abrogates the need for the conversion of intensity data to amplitudes, which is usually performed with the French and Wilson method [French & Wilson (1978), Acta Cryst. A35, 517-525], wherever likelihood target functions are required. It has general applicability for a wide variety of algorithms in macromolecular crystallography, including scaling, characterizing anisotropy and translational noncrystallographic symmetry, detecting outliers, experimental phasing, molecular replacement and refinement. Because it is impossible to reliably recover the original intensity data from amplitudes, it is suggested that crystallographers should always deposit the intensity data in the Protein Data Bank.

  18. Magnetic anisotropy induced by crystallographic orientation and morphological alignment in directionally-solidified eutectic Mn-Sb alloy

    Science.gov (United States)

    Lou, Chang-Sheng; Liu, Tie; Dong, Meng; Wu, Chun; Shao, Jian-Guo; Wang, Qiang

    2017-02-01

    The influences of the crystallographic orientation and morphological alignment upon the magnetic anisotropic behavior of polycrystalline materials were investigated. Microstructures obtained in eutectic Mn-Sb alloys via directional solidification simultaneously displayed crystallographic orientation and morphological alignment. Both the crystallographic orientation and the morphological alignment were able to induce magnetic anisotropy in the alloys, wherein the influence of the crystallographic orientation and the morphological alignment upon the magnetic anisotropic behavior of the alloys strongly depended upon their directions and exhibited either mutual promotion or competition. These findings may provide useful guidance for the fabrication design of functional magnetic materials.

  19. Crystal structures of 3-fluoro-N-[2-(tri-fluoro-meth-yl)phen-yl]benzamide, 3-bromo-N-[2-(tri-fluoro-meth-yl)phen-yl]benzamide and 3-iodo-N-[2-(tri-fluoro-meth-yl)phen-yl]benzamide.

    Science.gov (United States)

    Suchetan, P A; Suresha, E; Naveen, S; Lokanath, N K

    2016-06-01

    In the title compounds, C14H9F4NO, (I), C14H9BrF3NO, (II), and C14H9F3INO, (III), the two benzene rings are inclined to one another by 43.94 (8)° in mol-ecule A and 55.66 (7)° in mol-ecule B of compound (I), which crystallizes with two independent mol-ecules in the asymmetric unit, but by only 10.40 (12)° in compound (II) and 12.5 (2)° in compound (III). In the crystals of all three compounds, N-H⋯O hydrogen bonds link the mol-ecules to form chains propagating along the a-axis direction for (I), and along the b-axis direction for (II) and (III). In the crystal of (I), -A-B-A-B- chains are linked by C-H⋯O hydrogen bonds, forming layers parallel to (010). Within the layers there are weak offset π-π inter-actions present [inter-centroid distances = 3.868 (1) and 3.855 (1) Å]. In the crystals of (II) and (III), the chains are linked via short halogen-halogen contacts [Br⋯Br = 3.6141 (4) Å in (II) and I⋯I = 3.7797 (5) Å in (III)], resulting in the formation of ribbons propagating along the b-axis direction.

  20. Crystal structure of (E)-2-[(2-bromopyridin-3-yl)methyl-idene]-6-meth-oxy-3,4-di-hydro-naphthalen-1(2H)-one and 3-[(E)-(6-meth-oxy-1-oxo-1,2,3,4-tetra-hydro-naphthalen-2-ylidene)meth-yl]pyridin-2(1H)-one.

    Science.gov (United States)

    Zingales, Sarah K; Moore, Morgan E; Goetz, Andrew D; Padgett, Clifford W

    2016-07-01

    The title compounds C17H14BrNO2, (I), and C17H15NO3, (II), were obtained from the reaction of 6-meth-oxy-3,4-di-hydro-2H-naphthalen-1-one and 2-bromo-nicotinaldehyde in ethanol. Compound (I) was the expected product and compound (II) was the oxidation product from air exposure. In the crystal structure of compound (I), there are no short contacts or hydrogen bonds. The structure does display π-π inter-actions between adjacent benzene rings and adjacent pyridyl rings. Compound (II) contains two independent mol-ecules, A and B, in the asymmetric unit; both are non-planar, the dihedral angles between the meth-oxy-benzene and 1H-pyridin-2-one mean planes being 35.07 (9)° in A and 35.28 (9)°in B. In each mol-ecule, the 1H-pyridin-2-one unit participates in inter-molecular N-H⋯O hydrogen bonding to another mol-ecule of the same type (A to A or B to B). The structure also displays π-π inter-actions between the pyridyl and the benzene rings of non-equivalent mol-ecules (viz., A to B and B to A).

  1. 6-Amino-5-(1-amino-2,2-dicyano-vin-yl)-3,3a,4,5-tetra-hydro-2H-indene-4-spiro-1'-cyclo-pentane-3a,7-dicarbonitrile-thio-phene-2-carbaldehyde (1/0.5).

    Science.gov (United States)

    Asiri, Abdullah M; Ng, Seik Weng

    2010-09-04

    In each of the two independent indene-4-spiro-pentane mol-ecules in the asymmetric unit of the title 2:1 adduct, C(19)H(18)N(6)·0.5C(5)H(4)OS, the cyclo-hexene ring adopts a half-chair conformation and the cyclo-pentene and cyclo-pentane rings adopt envelope conformations. The mean plane through the cyclo-hexene/cyclo-pentene fused system is aligned at a dihedral angle of 77.9 (1)° with respect to the mean plane through the cyclo-pentane ring in one mol-ecule and 87.0 (1)° in the other. In the crystal, adjacent indene-4-spiro-pentane mol-ecules are linked by N-H⋯N hydrogen bonds into a three-dimensional network. The spaces within the network are occupied by the thio-phene-2-carbaldehyde mol-ecules. The thio-phene-2-carbaldehyde unit is disordered over two positions of equal occupancy. The crystal studied was found to be a non-morohedral twin with two minor twin components of 18.4 and 9.7%.

  2. Two tautomers in the same crystal: 3-(4-fluoro-phen-yl)-1H-pyrazole and 5-(4-fluoro-phen-yl)-1H-pyrazole.

    Science.gov (United States)

    Yamuna, Thammarse S; Kaur, Manpreet; Jasinski, Jerry P; Anderson, Brian J; Yathirajan, H S

    2014-09-01

    The title co-crystal, 3-(4-fluoro-phen-yl)-1H-pyrazole-5-(4-fluoro-phen-yl)-1H-pyrazole (1/1), C9H7FN2, crystallizes with four independent mol-ecules (A, B, C and D) in the asymmetric unit exhibiting two tautomeric forms (A and D; B and C) due to N-H proton exchange between the two N atoms of the pyrazole ring. The dihedral angles between the mean planes of the pyrazole and benzene rings are 15.6 (1), 19.8 (9), 14.0 (1) and 10.7 (7)° in mol-ecules A, B, C and D, respectively. In the crystal, N-H⋯N hydrogen bonds link the four mol-ecules in the asymmetric unit into a ring with an R 4 (4)(12) motif. Furthermore, weak C-H⋯F inter-actions link the mol-ecules into a three-dimensional network.

  3. Experimental and Theoretical Investigation of Crystallographic Orientation Dependence of Nanoscratching of Single Crystalline Copper

    Science.gov (United States)

    Geng, Yanquan; Zhang, Junjie; Yan, Yongda; Yu, Bowen; Geng, Lin; Sun, Tao

    2015-01-01

    In the present work, we perform experiments and molecular dynamics simulations to elucidate the underlying deformation mechanisms of single crystalline copper under the load-controlled multi-passes nanoscratching using a triangular pyramidal probe. The correlation of microscopic deformation behavior of the material with macroscopically-observed machining results is revealed. Moreover, the influence of crystallographic orientation on the nanoscratching of single crystalline copper is examined. Our simulation results indicate that the plastic deformation of single crystalline Cu under the nanoscratching is exclusively governed by dislocation mechanisms. However, there is no glissile dislocation structure formed due to the probe oscillation under the load-controlled mode. Both experiments and MD simulations demonstrate that the machined surface morphologies in terms of groove depth and surface pile-up exhibit strong crystallographic orientation dependence, because of different geometries of activated slip planes cutting with free surfaces and strain hardening abilities associated with different crystallographic orientations. PMID:26147506

  4. Experimental and Theoretical Investigation of Crystallographic Orientation Dependence of Nanoscratching of Single Crystalline Copper.

    Directory of Open Access Journals (Sweden)

    Yanquan Geng

    Full Text Available In the present work, we perform experiments and molecular dynamics simulations to elucidate the underlying deformation mechanisms of single crystalline copper under the load-controlled multi-passes nanoscratching using a triangular pyramidal probe. The correlation of microscopic deformation behavior of the material with macroscopically-observed machining results is revealed. Moreover, the influence of crystallographic orientation on the nanoscratching of single crystalline copper is examined. Our simulation results indicate that the plastic deformation of single crystalline Cu under the nanoscratching is exclusively governed by dislocation mechanisms. However, there is no glissile dislocation structure formed due to the probe oscillation under the load-controlled mode. Both experiments and MD simulations demonstrate that the machined surface morphologies in terms of groove depth and surface pile-up exhibit strong crystallographic orientation dependence, because of different geometries of activated slip planes cutting with free surfaces and strain hardening abilities associated with different crystallographic orientations.

  5. Evolution of the preferred crystallographic orientation across the thickness of nickel electrodeposits

    DEFF Research Database (Denmark)

    Alimadadi, Hossein; da Silva Fanta, Alice Bastos; Somers, Marcel A. J.;

    Numerous industrial applications of nickel electrodeposits, like for example as microcomponents, essentially depend on their preferred crystallographic orientation. As a function of the electrodeposition conditions, the microstructure can be tailored with respect to the size, shape...... for such advanced investigations. The present work reports on the evolution of the preferred crystallographic orientation on the example of various fiber textured nickel electrodeposits. Tailored electrodeposition provided nickel deposits with different fibre textures being , , and ... and crystallographic orientation of grains. Thorough microstructure characterization, however, is not straightforward, because the microstructure of electrodeposits often changes across the thickness of the deposits and numerous twin orientations even with nano-size dimensions can evolve during growth of the deposits...

  6. Advanced yield strength of interconnector ribbon for photovoltaic module using crystallographic texture control

    Science.gov (United States)

    Kang, Byungjun; Park, Nochang; Tark, Sung Ju; Oh, Won Wook; Park, Sungeun; Kim, Young Do; Lee, Hae-Seok; Kim, Donghwan

    2014-03-01

    This paper reports a study on reducing the yield strength of Cu ribbon wire used for Si solar cell interconnections in solar panels. Low yield strength Cu core should be used as the interconnector ribbon to minimize the fracture of Si solar cells during the tabbing process. We lowered the yield strength of Cu ribbon by controlling the crystallographic texture without increasing the annealing time and temperature. The crystallographic texture was controlled by lubrication in a cold rolling process. The crystallographic texture was observed by scanning electron microscopy with electron back scattered diffraction. A tensile test was performed for the comparison of the mechanical properties of Cu with and without lubrication. The average yield strength was 91.2 MPa with lubrication whereas the yield strength was 99.6 MPa without lubrication. The lower value of the lubricated samples seemed to be caused by the higher cube texture intensity than that of the samples without lubrication.

  7. The Ultrasonic Measurement of Crystallographic Orientation for Imaging Anisotropic Components with 2d Arrays

    Science.gov (United States)

    Lane, C. J. L.; Dunhill, A. K.; Drinkwater, B. W.; Wilcox, P. D.

    2011-06-01

    Single crystal components are used widely in the gas-turbine industry. However, these components are elastically anisotropic which causes difficulties when performing NDE inspections with ultrasound. Recently an ultrasonic algorithm for a 2D array has been corrected to perform the reliable volumetric inspection of single crystals. For the algorithm to be implemented the crystallographic orientation of the components must be known. This paper, therefore, develops and reviews crystallographic orientation methods using 2D ultrasonic arrays. The methods under examination are based on the anisotropic propagation of surface and bulk waves and an image-based orientation method is also considered.

  8. Elasto-Plastic Behavior of High RRR Niobium: Effects of Crystallographic Texture, Microstructure and Hydrogen Concentration

    Energy Technology Data Exchange (ETDEWEB)

    G.R. Myneni; S.R. Agnew

    2002-11-01

    Conventional assessments of the mechanical properties of polycrystalline high RRR niobium via tensile testing have revealed unusually low apparent Young's moduli and yield strength in annealed samples. These observations motivated the current investigation of a variety of possible contributors: crystallographic texture, grain size, and impurity concentration. It is shown that the crystallographic textures of a single lot of niobium are essentially unchanged by post-recrystallization anneals at temperatures up to 800 C. Ultrasonic measurements reveal that the elastic response is not degraded by annealing. Rather, the material's extremely low yield point gives the impression of a low elastic modulus during tensile testing.

  9. Crystallographic preferred orientation and deformation of deep Earth minerals

    Science.gov (United States)

    Kaercher, Pamela Michelle

    This thesis aims to provide further insight into crystallographic preferred orientation (CPO) and deformation mechanisms active at high pressure. Preferred orientation of iron-rich magnesiowustite (Mg,Fe)O, a major mantle mineral phase, stishovite (SiO2), the high pressure polymorph of quartz that is likely present in the lower crust and mantle, and in NaMgF3 + NaCl, an analog system to lower mantle minerals MgSiO3 + MgO, have been examined with synchrotron X-ray diffraction while at high pressure in either a diamond anvil cell or a multianvil press. Magnesiowustite, (Mg0.08Fe0.88)O, and wustite, Fe0.94O, were compressed up to 37 GPa at ambient temperature in diamond anvil cells (DAC) at the Advanced Light Source (ALS). X-ray diffraction patterns were taken in situ in radial geometry in order to study the evolution of CPO through the cubic-to-rhombohedral phase transition. Under uniaxial stress in the DAC, cubic texture developed (i.e. {100} c planes aligned perpendicular to the compression direction). Variant selection of preferred orientation was observed immediately following the transition to the rhombohedral phase. Upon decompression in the DAC, FeO reverted back to cubic symmetry and the cubic texture reappeared, demonstrating that the transition is reversible and has texture memory. The crystal structure of the high pressure SiO2 polymorph stishovite has been studied in detail, but little is known about texture development during deformation, which provides information for understanding subduction of quartz-bearing crustal rocks into the mantle. Radial DAC experiments were done at the ALS and the Advanced Photon Source (APS) while collecting X-ray diffraction patterns in radial geometry to examine in situ development of CPO. Starting pressure in the sample chamber was still in the quartz stability field, and compression of quartz produced a weak texture, likely due to Dauphine twinning. Following compression of quartz into the stishovite stability field

  10. Crystallographic Analysis of Nucleation at Hardness Indentations in High-Purity Aluminum

    DEFF Research Database (Denmark)

    Xu, Chaoling; Zhang, Yubin; Lin, Fengxiang

    2016-01-01

    Nucleation at Vickers hardness indentations has been studied in high-purity aluminum cold-rolled 12 pct. Electron channeling contrast was used to measure the size of the indentations and to detect nuclei, while electron backscattering diffraction was used to determine crystallographic orientations...

  11. Interpretation of quantitative crystallographic texture in copper electrodeposits on amorphous substrates

    DEFF Research Database (Denmark)

    Pantleon, Karen; Jensen, Jens Arne Dahl; Somers, Marcel A. J.

    2004-01-01

    Crystallographic texture and morphology in Cu electrodeposits was studied in relation to the current density and the content of the organic levelling additive 3-mercapto-1-propanesulfonate. The substrate onto which Cu was electrodeposited consisted of amorphous Ni-P in order to allow substrate...

  12. Crystallographic structural organization of human rhinovirus serotype 16, 14, 3, 2 and 1A

    Science.gov (United States)

    Janner, A.

    2006-07-01

    The capsid of the icosahedral virion is encapsulated between two polyhedra scaled according to the golden mean, each being composed of an icosahedron and a dodecahedron. Structural units of the coat proteins are enclosed into forms whose projections along the icosahedral symmetry axes obey the crystallographic law of rational indices.

  13. Are Independent Fiscal Institutions Really Independent?

    Directory of Open Access Journals (Sweden)

    Slawomir Franek

    2015-08-01

    Full Text Available In the last decade the number of independent fiscal institutions (known also as fiscal councils has tripled. They play an important oversight role over fiscal policy-making in democratic societies, especially as they seek to restore public finance stability in the wake of the recent financial crisis. Although common functions of such institutions include a role in analysis of fiscal policy, forecasting, monitoring compliance with fiscal rules or costing of spending proposals, their roles, resources and structures vary considerably across countries. The aim of the article is to determine the degree of independence of such institutions based on the analysis of the independence index of independent fiscal institutions. The analysis of this index values may be useful to determine the relations between the degree of independence of fiscal councils and fiscal performance of particular countries. The data used to calculate the index values will be derived from European Commission and IMF, which collect sets of information about characteristics of activity of fiscal councils.

  14. Central Bank independence

    Directory of Open Access Journals (Sweden)

    Vasile DEDU

    2012-08-01

    Full Text Available In this paper we present the key aspects regarding central bank’s independence. Most economists consider that the factor which positively influences the efficiency of monetary policy measures is the high independence of the central bank. We determined that the National Bank of Romania (NBR has a high degree of independence. NBR has both goal and instrument independence. We also consider that the hike of NBR’s independence played an important role in the significant disinflation process, as headline inflation dropped inside the targeted band of 3% ± 1 percentage point recently.

  15. Crystal structure of tri-hydrogen bis-{[1,1,1-tris-(2-oxido-ethyl-amino-meth-yl)ethane]-cobalt(III)} trinitrate.

    Science.gov (United States)

    Sethi, Waqas; Johannesen, Heini V; Morsing, Thorbjørn J; Piligkos, Stergios; Weihe, Høgni

    2015-12-01

    The title compound, [Co2(L)2](3+)·3NO3 (-) [where L = CH3C(CH2NHCH2CH2OH1/2)3], has been synthesized from the ligand 1,1,1-tris-(2-hy-droxy-ethyl-amino-meth-yl)ethane. The cobalt(III) dimer has an inter-esting and uncommon O-H⋯O hydrogen-bonding motif with the three bridging hy-droxy H atoms each being equally disordered over two positions. In the dimeric trication, the octa-hedrally coordinated Co(III) atoms and the capping C atoms lie on a threefold rotation axis. The N atoms of two crystallographically independent nitrate anions also lie on threefold rotation axes. N-H⋯O hydrogen bonding between the complex cations and nitrate anions leads to the formation of a three-dimensional network structure. The compound is a racemic conglomerate of crystals containing either d or l mol-ecules. The crystal used for this study is a d crystal.

  16. Disorder of the dimeric TCNQ-TCNQ unit in the crystal structure of [Ni(bpy)3]2(TCNQ-TCNQ)(TCNQ)2·6H2O (TCNQ is 7,7,8,8-tetra-cyano-quinodi-methane).

    Science.gov (United States)

    Černák, Juraj; Kuchár, Juraj; Hegedüs, Michal

    2017-01-01

    Crystallization from an aqueous methanol system composed of Ni(NO3)2, 2,2'-bipyridine (bpy) and LiTCNQ (TCNQ is 7,7,8,8-tetra-cyano-quinodi-methane) in a 1:3:2 molar ratio yielded single crystals of bis-[tris-(2,2'-bi-pyridine-κ(2)N,N')nickel(II)] bis-(7,7,8,8-tetra-cyano-quinodi-methane radical anion) bi[7,7,8,8-tetra-cyano-quino-dimethanide] hexa-hydrate, [Ni(C10H8N2)3]2(C24H8N8)(C12H4N4)2·6H2O or [Ni(bpy)3]2(TCNQ-TCNQ)(TCNQ)2·6H2O. The crystal structure comprises [Ni(bpy)3](2+) complex cations, two centrosymmetric crystallographically independent TCNQ (·-) anion radicals with π-stacked exo groups, and an additional dimeric TCNQ-TCNQ unit which comprises 75.3 (9)% of a σ-dimerized (TCNQ-TCNQ)(2-) dianion and 24.7 (9)% of two TCNQ(·-) anion radicals with tightly π-stacked exo groups. The title complex represents the first example of an Ni(II) complex containing a σ-dimerized (TCNQ-TCNQ)(2-) dianion. Disordered solvent water mol-ecules present in the crystal structure participate in hydrogen-bonding inter-actions.

  17. The relation between microstructure and crystallographic orientation in rolled copper and brass

    DEFF Research Database (Denmark)

    Christoffersen, H.; Leffers, Torben

    2002-01-01

    The relation between microstructure and crystallographic orientation is investigated in rolled copper and brass. For the two main types of microstructure in copper (the high wall density and the low wall density structure) there is a certain relation: theorientations corresponding to a specific...... type tend to cluster in certain regions of orientation space. However, the clustering is not very pronounced (there is a lot of overlap), and it cannot be related to any model. There is also a certain grain-sizeeffect: the average grain with high wall density structure is larger than the average grain...... with low wall density structure. For a third type of microstructure (to be described) there is a very clear relation to the crystallographic orientation. For brassthe distinction is between grains with and grains without deformation twins. There is a clear trend for the grains with twins to cluster...

  18. Crystallographic dependence of CO activation on cobalt catalysts: HCP versus FCC.

    Science.gov (United States)

    Liu, Jin-Xun; Su, Hai-Yan; Sun, Da-Peng; Zhang, Bing-Yan; Li, Wei-Xue

    2013-11-06

    Identifying the structure sensitivity of catalysts in reactions, such as Fischer-Tropsch synthesis from CO and H2 over cobalt catalysts, is an important yet challenging issue in heterogeneous catalysis. Based on a first-principles kinetic study, we find for the first time that CO activation on hexagonal close-packed (HCP) Co not only has much higher intrinsic activity than that of face centered-cubic (FCC) Co but also prefers a different reaction route, i.e., direct dissociation with HCP Co but H-assisted dissociation on the FCC Co. The origin is identified from the formation of various denser yet favorable active sites on HCP Co not available for FCC Co, due to their distinct crystallographic structure and morphology. The great dependence of the activity on the crystallographic structure and morphology of the catalysts revealed here may open a new avenue for better, stable catalysts with maximum mass-specific reactivity.

  19. Novel Kac-Moody-type affine extensions of non-crystallographic Coxeter groups

    CERN Document Server

    Dechant, Pierre-Philippe; Twarock, Reidun

    2011-01-01

    Motivated by recent results in mathematical virology, we present novel asymmetric Z[tau]-integer-valued affine extensions of the non-crystallographic Coxeter groups H_2, H_3 and H_4 derived in a Kac-Moody-type formalism. In particular, we show that the affine reflection planes which extend the Coxeter group H_3 generate (twist) translations along 2-, 3- and 5-fold axes of icosahedral symmetry and classify these translations in terms of Fibonacci recursion relations, thus providing a framework to explain results of Keef et al and Wardman at the group level. Finally, we extend this classification to the case of the non-crystallographic Coxeter groups H_2 and H_4. These results should have applications in physics (quasicrystals), biology (viruses) and chemistry (fullerenes).

  20. Determination of crystallographic and macroscopic orientation of planar structures in TEM

    DEFF Research Database (Denmark)

    Huang, X.; Liu, Q.

    1998-01-01

    With the aid of a double-tilt holder in a transmission electron microscope (TEM), simple methods are described for determination of the crystallographic orientation of a planar structure and for calculation of the macroscopic orientation of the planar structure. The correlation between a planar s...... taken at tilted positions, can be transformed to the real macroscopic orientation of the planar structures with estimated error of about +/- 2 degrees. (C) 1998 Elsevier Science B.V. All rights reserved....... structure and a crystallographic plane can be found by comparing the differences in their trace directions on the projection plane and inclination angles with respect to that plane. The angles between the traces of planar structures and the sample axis measured from the TEM micrographs, which have been...

  1. Acanthamoeba polyphaga mimivirus NDK: preliminary crystallographic analysis of the first viral nucleoside diphosphate kinase.

    Science.gov (United States)

    Jeudy, Sandra; Coutard, Bruno; Lebrun, Régine; Abergel, Chantal

    2005-06-01

    The complete sequence of the largest known double-stranded DNA virus, Acanthamoeba polyphaga mimivirus, has recently been determined [Raoult et al. (2004), Science, 306, 1344-1350] and revealed numerous genes not expected to be found in a virus. A comprehensive structural and functional study of these gene products was initiated [Abergel et al. (2005), Acta Cryst. F61, 212-215] both to better understand their role in the virus physiology and to obtain some clues to the origin of DNA viruses. Here, the preliminary crystallographic analysis of the viral nucleoside diphosphate kinase protein is reported. The crystal belongs to the cubic space group P2(1)3, with unit-cell parameter 99.425 A. The self-rotation function confirms that there are two monomers per asymmetric unit related by a twofold non-crystallographic axis and that the unit cell thus contains four biological entities.

  2. Preferred crystallographic orientation in the ice I ← II transformation and the flow of ice II

    Science.gov (United States)

    Bennett, K.; Wenk, H.-R.; Durham, W.B.; Stern, L.A.; Kirby, S.H.

    1997-01-01

    The preferred crystallographic orientation developed during the ice I ← II transformation and during the plastic flow of ice II was measured in polycrystalline deuterium oxide (D2O) specimens using low-temperature neutron diffraction. Samples partially transformed from ice I to II under a non-hydrostatic stress developed a preferred crystallographic orientation in the ice II. Samples of pure ice II transformed from ice I under a hydrostatic stress and then when compressed axially, developed a strong preferred orientation of compression axes parallel to (1010). A match to the observed preferred orientation using the viscoplastic self-consistent theory was obtained only when (1010) [0001] was taken as the predominant slip system in ice II.

  3. Mineralogical, crystallographic and morphological characteristics of natural kaolins from the Ivory Coast (West Africa)

    Science.gov (United States)

    Sei, J.; Morato, F.; Kra, G.; Staunton, S.; Quiquampoix, H.; Jumas, J. C.; Olivier-Fourcade, J.

    2006-10-01

    Thirteen clay samples from four deposits in the Ivory Coast (West Africa) were studied using X-ray diffraction, thermogravimetric analysis and chemical analysis. Mineralogical, crystallographic and morphological characteristics of these samples are given. Kaolinite is the principal mineral but other minerals are present in small quantities: illite, quartz, anatase and iron oxides (oxides and oxyhydroxides). The crystallographic, morphological and surface characteristics are influenced by the presence of these impurities. In particular, the presence of iron oxides was associated with reduced structural ordering and thermal stability of kaolinite and increased specific surface area. These clays could be used in the ceramics industry to make tiles and bricks, and also in agronomy as supports for chemical fertilizers or for environmental protection by immobilising potentially toxic waste products.

  4. Crystallographic Analysis of Nucleation at Hardness Indentations in High-Purity Aluminum

    Science.gov (United States)

    Xu, Chaoling; Zhang, Yubin; Lin, Fengxiang; Wu, Guilin; Liu, Qing; Juul Jensen, Dorte

    2016-12-01

    Nucleation at Vickers hardness indentations has been studied in high-purity aluminum cold-rolled 12 pct. Electron channeling contrast was used to measure the size of the indentations and to detect nuclei, while electron backscattering diffraction was used to determine crystallographic orientations. It is found that indentations are preferential nucleation sites. The crystallographic orientations of the deformed grains affect the hardness and the nucleation potentials at the indentations. Higher hardness gives increased nucleation probabilities. Orientation relationships between nuclei developed at different indentations within one original grain are analyzed and it is found that the orientation distribution of the nuclei is far from random. It is suggested that it relates to the orientations present near the indentation tips which in turn depend on the orientation of the selected grain in which they form. Finally, possible nucleation mechanisms are briefly discussed.

  5. Expression, purification and preliminary crystallographic characterization of FlhF from Bacillus subtilis

    Energy Technology Data Exchange (ETDEWEB)

    Bange, Gert; Petzold, Georg; Wild, Klemens; Sinning, Irmgard, E-mail: irmi.sinning@bzh.uni-heidelberg.de [Heidelberg University Biochemistry Centre (BZH), INF 328, 69120 Heidelberg (Germany)

    2007-05-01

    Preliminary crystallographic data are reported for the third SRP GTPase FlhF from Bacillus subtilis. The Gram-positive bacterium Bacillus subtilis contains three proteins belonging to the signal recognition particle (SRP) type GTPase family. The well characterized signal sequence-binding protein SRP54 and the SRP receptor protein FtsY are universally conserved components of the SRP system of protein transport. The third member, FlhF, has been implicated in the placement and assembly of polar flagella. This article describes the overexpression and preliminary X-ray crystallographic analysis of an FlhF fragment that corresponds to the well characterized GTPase domains in SRP54 and FtsY. Three crystal forms are reported with either GDP or GMPPNP and diffract to a resolution of about 3 Å.

  6. Crystallographic orientation and induced potential effects in photoelectron emission from metal surfaces by ultrashort laser pulses

    CERN Document Server

    Rubiano, C A Rios; Mitnik, D M; Silkin, V M; Gravielle, M S

    2016-01-01

    The influence of the crystallographic orientation of a typical metal surface, like aluminum, on electron emission spectra produced by grazing incidence of ultrashort laser pulses is investigated by using the band-structure-based-Volkov (BSB-V) approximation. The present version of the BSB-V approach includes not only a realistic description of the surface interaction, accounting for band structure effects, but also effects due to the induced potential that originates from the collective response of valence-band electrons to the external electromagnetic field. The model is applied to evaluate differential electron emission probabilities from the valence band of Al(100) and Al(111). For both crystallographic orientations, the contribution of partially occupied surface electronic states and the influence of the induced potential are separately analyzed as a function of the laser carrier frequency. We found that the induced potential strongly affects photoelectron emission distributions, opening a window to scrut...

  7. Crystallographic similarity between the lath martensite and lower bainite in medium-carbon alloy steels

    Institute of Scientific and Technical Information of China (English)

    LIU Jiangwen; LUO Chengping; WU Dongxiao

    2005-01-01

    Progress in the crystallography of lath martensitic and lower bainitic transformations is briefly reviewed, followed by a presentation of the experimentally measured crystallographic characteristics of both lath martensite and lower bainite formed in mediumcarbon steels containing Si, Mn and Mo. It is found that the bainite plates relate to each other by a relative rotation of 54.7°or 60°about the normal to their common close-packed planes {110} b, which ensures a pseudo- {112}b twin relationship between two adjacent plates,and that all bainite variants formed in a single packet keep a unique G-T orientation relationship with the austenite matrix. These two types of OR of lower bainite are similar to that of the lath martensite, respectively. Furthermore, the measured habit planes of both the lower bainite and lath martensite are all {335} f type, which can verify the crystallographic similarity between the lath martensite and lower bainite.

  8. Microstructure, crystallographic texture and mechanical properties of friction stir welded AA2017A

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, M.M.Z., E-mail: mohamed_ahmed4@s-petrol.suez.edu.eg [Institute for Microstructural and Mechanical Processing Engineering, University of Sheffield (IMMPETUS), Mappin Street, Sheffield S1 3JD (United Kingdom); Department of Metallurgical and Materials Engineering, Suez Canal University, Suez 43721 (Egypt); Wynne, B.P.; Rainforth, W.M. [Institute for Microstructural and Mechanical Processing Engineering, University of Sheffield (IMMPETUS), Mappin Street, Sheffield S1 3JD (United Kingdom); Threadgill, P.L. [TWI LTD, Granta Park, Great Abington, Cambridge CB21 6AL (United Kingdom)

    2012-02-15

    In this study a thick section (20 mm) friction stir welded AA2017A-T451 has been characterized in terms of microstructure, crystallographic texture and mechanical properties. For microstructural analysis both optical and scanning electron microscopes have been used. A detailed crystallographic texture analysis has been carried out using the electron back scattering diffraction technique. Crystallographic texture has been examined in both shoulder and probe affected regions of the weld NG. An entirely weak texture is observed at the shoulder affected region which is mainly explained by the effect of the sequential multi pass deformation experienced by both tool probe and tool shoulder. The texture in the probe dominated region at the AS side of the weld is relatively weak but still assembles the simple shear texture of FCC metals with B/B{sup Macron} and C components existing across the whole map. However, the texture is stronger at the RS than at the AS of the weld, mainly dominated byB/B{sup Macron} components and with C component almost absent across the map. An alternating bands between (B) components and (B{sup Macron }) component are observed only at the AS side of the weld. - Highlights: Black-Right-Pointing-Pointer Detailed investigation of microstructure and crystallographic texture. Black-Right-Pointing-Pointer The grain size is varied from the top to the bottom of the NG. Black-Right-Pointing-Pointer An entirely weak texture is observed at the shoulder affected region. Black-Right-Pointing-Pointer The texture in the probe affected region is dominated by simple shear texture.

  9. Crystallographic orientation-dependent pattern replication in direct imprint of aluminum nanostructures

    OpenAIRE

    2015-01-01

    In the present work, we perform molecular dynamics simulations corroborated by experimental validations to elucidate the underlying deformation mechanisms of single-crystalline aluminum under direct imprint using a rigid silicon master. We investigate the influence of crystallographic orientation on the microscopic deformation behavior of the substrate materials and its correlation with the macroscopic pattern replications. Furthermore, the surface mechanical properties of the patterned struc...

  10. Experimental and Theoretical Investigation of Crystallographic Orientation Dependence of Nanoscratching of Single Crystalline Copper

    OpenAIRE

    2015-01-01

    In the present work, we perform experiments and molecular dynamics simulations to elucidate the underlying deformation mechanisms of single crystalline copper under the load-controlled multi-passes nanoscratching using a triangular pyramidal probe. The correlation of microscopic deformation behavior of the material with macroscopically-observed machining results is revealed. Moreover, the influence of crystallographic orientation on the nanoscratching of single crystalline copper is examined....

  11. Crystallographic mechanism of inverse twinning in ordered β′-CuZn alloy

    Institute of Scientific and Technical Information of China (English)

    毛卫民

    2000-01-01

    The basic process of mechanical twinning in β’-CuZn phase, as an example of B2 structured metals, has been analyzed under the rolling stresses. The behavior of inverse twinning in B2 structured metals is discussed in terms of mechanics and crystallographic stability. It is shown that the inverse twinning could remain the B2 structure, and the resulting strains will have the lowest resistance during the rolling deformation of the polycrystalline.

  12. Crystallographic mechanism of inverse twinning in ordered β'-CuZn alloy

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The basic process of mechanical twinning in β'-CuZn phase, as an example of B2 structured metals, has been analyzed under the rolling stresses. The behavior of inverse twinning in B2 structured metals is discussed in terms of mechanics and crystallographic stability. It is shown that the inverse twinning could remain the B2 structure, and the resulting strains will have the lowest resistance during the rolling deformation of the polycrystalline.

  13. Crystallization and preliminary crystallographic characterization of an SH3 domain from the IB1 scaffold protein

    DEFF Research Database (Denmark)

    Dar, Imran; Bonny, Christophe; Pedersen, Jan Torleif

    2003-01-01

    with unmodified protein and deliberately oxidized protein have led to different crystal forms. X-ray data have been collected to 3.0 A resolution from a crystal form with rectangular prism morphology. These crystals are orthorhombic (P2(1)2(1)2(1)), with unit-cell parameters a = 45.9, b = 57.0, c = 145.5 A....... These are the first crystallographic data on a scaffold molecule such as IB1 to be reported....

  14. Keep it together: restraints in crystallographic refinement of macromolecule–ligand complexes

    Science.gov (United States)

    Steiner, Roberto A.; Tucker, Julie A.

    2017-01-01

    A short introduction is provided to the concept of restraints in macromolecular crystallographic refinement. A typical ligand restraint-generation process is then described, covering types of input, the methodology and the mechanics behind the software in general terms, how this has evolved over recent years and what to look for in the output. Finally, the currently available restraint-generation software is compared, concluding with some thoughts for the future. PMID:28177305

  15. [μ-Bis(diphenyl-arsino)methane-1:2κAs:As'][bis-(4-methoxy-phen-yl)phenyl-phosphine-3κP]-nona-carbonyl-1κC,2κC,3κC-triangulo-tri-ruthenium(0) dichloro-methane 0.15-solvate.

    Science.gov (United States)

    Shawkataly, Omar Bin; Khan, Imthyaz Ahmed; Yeap, Chin Sing; Fun, Hoong-Kun

    2010-01-30

    The asymmetric unit of the title triangulo-triruthenium compound, [Ru(3)(C(25)H(22)As(2))(C(20)H(19)O(2)P)(CO)(9)]·0.15CH(2)Cl(2), contains one mol-ecule of the triangulo-triruthenium complex and one partially occupied dichloro-methane solvent mol-ecule. The dichloro-methane solvent lies across a crystallographic inversion center leading to the mol-ecule being disordered over two positions of equal occupancy. The bis-(diphenyl-arsino)methane ligand bridges an Ru-Ru bond and the monodentate arsine ligand bonds to the third Ru atom. Both the arsine ligands are equatorial with respect to the Ru(3) triangle. In addition, each Ru atom carries one equatorial and two axial terminal carbonyl ligands. The three phospho-rus-bound benzene rings make dihedral angles of 72.7 (3), 80.9 (3) and 70.8 (2)° with each other. The dihedral angles between the two benzene rings are 79.9 (3) and 81.5 (2)° for the two diphenyl-arsino groups.

  16. Crystal structure of bis-(2-{[1,1-bis-(hy-droxy-meth-yl)-2-oxidoeth-yl]imino-meth-yl}-6-meth-oxy-phenolato)manganese(IV) 0.39-hydrate.

    Science.gov (United States)

    Buvaylo, Elena A; Vassilyeva, Olga Yu; Skelton, Brian W

    2015-11-01

    The title compound, [Mn(C12H15NO5)2]·0.39H2O, is a 0.39 hydrate of the isostructural complex bis-(2-{[1,1-bis-(hy-droxy-meth-yl)-2-oxidoeth-yl]imino-meth-yl}-6-meth-oxy-phenolato)manganese(IV) that has previously been reported by Back, Oliveira, Canabarro & Iglesias [Z. Anorg. Allg. Chem. (2015), 641, 941-947], based on room-temperature data. The current structure that was determined at 100 K reveals a lengthening of the c cell parameter compared with the published one due to the incorporation of the partial occupancy water mol-ecule. The title compound crystallizes in the tetra-gonal chiral space group P41212; the neutral [Mn(IV)(C12H15NO5)2] mol-ecule is situated on a crystallographic C 2 axis. The overall geometry about the central manganese ion is octa-hedral with an N2O4 core; each ligand acts as a meridional ONO donor. The coordination environment of Mn(IV) at 100 K displays a difference in one of the two Mn-O bond lengths, compared with the room-temperature structure. In the crystal, the neutral mol-ecules are stacked in a helical fashion along the c-axis direction.

  17. Selective crystallization of indigo B by a modified sublimation method and its redetermined structure.

    Science.gov (United States)

    Kettner, Florian; Hüter, Lucie; Schäfer, Johanna; Röder, Konstantin; Purgahn, Uta; Krautscheid, Harald

    2011-11-01

    Good-quality single crystals of the title compound, indigo B [systematic name: 2-(3-oxoindolin-2-yl-idene)indolin-3-one], C(16)H(10)N(2)O(2), have been prepared with high selectivity by a sublimation process. The previous structure of indigo B [Süsse & Wolf (1980 ▶). Naturwissenschaften, 67, 453], which showed that the complete mol-ecule is generated by crystallographic inversion symmetry has been confirmed, but the present study reports more realistic geometrical parameters and modern standards of precision (e.g. σ for C-C bonds = 0.002-0.003 Å). Each mol-ecule features two intra-molecular N-H⋯O hydrogen bonds. In the crystal, mol-ecules are linked by strong face-to-face π-π stacking inter-actions involving both the six- and five-membered rings [centroid-centroid separations = 3.6290 (14) and 3.6506 (14) Å] and inter-molecular N-H⋯O hydrogen bonds.

  18. Poly[[tri-μ-aqua-do-deca-aqua-tris-(μ3-1-hy-droxy-ethyl-idene-1,1-di-phospho-nato)tricalcium(II)tripalladium(II)] penta-hydrate].

    Science.gov (United States)

    Kutsenko, Irina P; Kozachkova, Alexandra N; Tsaryk, Natalia V; Pekhnyo, Vasily I; Rusanova, Julia A

    2014-08-01

    The asymmetric unit of the title compound, {[CaPd{CH3OHC(PO3)2}(H2O)5]·5/3H2O} n , consists of one half of the complex [Pd{CH3OHC(PO3)2}](2-) anion (point group symmetry m..), one Ca(2+) cation [site symmetry (.2.)] that is surrounded by three water mol-ecules (one of which is on the same rotation axis) and by three disordered lattice water mol-ecules. The anions form a trinuclear metallocycle around a crystallographic threefold rotation axis. The cations are related by a twofold rotation axis to form a [Ca2(H2O)10](2+) dimer. The slightly distorted square-planar coordination environment of the Pd(II) atoms in the complex anions is formed by O atoms of the bidentate chelating phospho-nate groups of the 1-hy-droxy-ethyl-idene-1,1-di-phospho-nate ligands. In the crystal, cations are bound to anions through -Ca-O-P-O- bonds, as well as through O-H⋯O hydrogen bonds, resulting in a three-dimensional polymer. The structure is completed by five disordered solvent mol-ecules localized in cavities within the framework.

  19. Disodium diaqua-bis-(methyl-enedi-phos-pho-nato-κO,O')cobaltate(II) dihydrate.

    Science.gov (United States)

    van Merwe, Kina; Visser, Hendrik G; Venter, Johan A

    2011-10-01

    In the title compound, Na(2)[Co(CH(4)O(6)P(2))(2)(H(2)O)(2)]·2H(2)O, the asymmetric unit is composed of one methyl-enediphospho-nate ligand and one water mol-ecule, which both are coordinated to a Co(II) atom, as well as a non-coordinated water mol-ecule and a sodium cation. The Co(II) atom occupies a special position on a crystallographic inversion centre. The slightly distorted Co(II)O(6) octa-hedral coordination environment is composed of two bidentate methyl-enediphospho-nate ligands and two coordinated water mol-ecules in trans positions. The sodium ion is octa-hedrally coordinated to six O atoms with Na-O distances ranging from 2.3149 (12) to 2.6243 (12) Å. An extensive three-dimensional network of inter-molecular as well as intra-molecular O-H⋯O and C-H⋯O hydrogen bonding inter-acions is present.

  20. Affine extensions of non-crystallographic Coxeter groups induced by projection

    Science.gov (United States)

    Dechant, Pierre-Philippe; BÅ`hm, Céline; Twarock, Reidun

    2013-09-01

    In this paper, we show that affine extensions of non-crystallographic Coxeter groups can be derived via Coxeter-Dynkin diagram foldings and projections of affine extended versions of the root systems E8, D6, and A4. We show that the induced affine extensions of the non-crystallographic groups H4, H3, and H2 correspond to a distinguished subset of those considered in [P.-P. Dechant, C. Bœhm, and R. Twarock, J. Phys. A: Math. Theor. 45, 285202 (2012)]. This class of extensions was motivated by physical applications in icosahedral systems in biology (viruses), physics (quasicrystals), and chemistry (fullerenes). By connecting these here to extensions of E8, D6, and A4, we place them into the broader context of crystallographic lattices such as E8, suggesting their potential for applications in high energy physics, integrable systems, and modular form theory. By inverting the projection, we make the case for admitting different number fields in the Cartan matrix, which could open up enticing possibilities in hyperbolic geometry and rational conformal field theory.

  1. Electron diffraction study of {alpha}-AlMnSi crystals including non-crystallographic axes

    Energy Technology Data Exchange (ETDEWEB)

    Song, G.L.; Bursill, L.A.

    1997-06-01

    The structure of crystalline {alpha}-AlMnSi is examined by electron diffraction. Six distinct zone axes are examined, including both normal crystallographic and non-crystallographic zones axes, allowing the space group symmetry to be studied. Electron diffraction patterns characteristic of Pm3-bar were obtained for thicker specimens. However, for very thin specimens, as used for HRTEM imaging, the electron diffraction patterns were characteristic of Im3-bar space group symmetry. The structural basis of the Pm3-bar to Im3-bar transformation may be understood in terms of an analysis of the icosahedral structural elements located at the corners and body-centers of the cubic unit cell. A method for indexing the non-crystallographic zone axis diffraction patterns is described. An electron diffraction pattern of the 5-fold axis of the quasicrystalline phase i-AlMnSi is also included; this is compared with the experimental results and calculations for the [0{tau}1] axis of Pm3-bar and Im3-bar crystalline phases. 26 refs., 4 tabs., 7 figs.

  2. Rapid Creation of Three-Dimensional, Tactile Models from Crystallographic Data

    Directory of Open Access Journals (Sweden)

    Nathan B. Fisher

    2016-01-01

    Full Text Available A method for the conversion of crystallographic information framework (CIF files to stereo lithographic data files suitable for printing on three-dimensional printers is presented. Crystallographic information framework or CIF files are capable of being manipulated in virtual space by a variety of computer programs, but their visual representations are limited to the two-dimensional surface of the computer screen. Tactile molecular models that demonstrate critical ideas, such as symmetry elements, play a critical role in enabling new students to fully visualize crystallographic concepts. In the past five years, major developments in three-dimensional printing has lowered the cost and complexity of these systems to a level where three-dimensional molecular models may be easily created provided that the data exists in a suitable format. Herein a method is described for the conversion of CIF file data using existing free software that allows for the rapid creation of inexpensive molecular models. This approach has numerous potential applications in basic research, education, visualization, and crystallography.

  3. Independent candidates in Mexico

    OpenAIRE

    Campos, Gonzalo Santiago

    2014-01-01

    In this paper we discuss the issue of independent candidates in Mexico, because through the so-called political reform of 2012 was incorporated in the Political Constitution of the Mexican United States the right of citizens to be registered as independent candidates. Also, in September 2013 was carried out a reform of Article 116 of the Political Constitution of the Mexican United States in order to allow independent candidates in each state of the Republic. However, prior to the constitutio...

  4. Central bank Financial Independence

    OpenAIRE

    J.Ramon Martinez-Resano

    2004-01-01

    Central bank independence is a multifaceted institutional design. The financial component has been seldom analysed. This paper intends to set a comprehensive conceptual background for central bank financial independence. Quite often central banks are modelled as robot like maximizers of some goal. This perspective neglects the fact that central bank functions are inevitably deployed on its balance sheet and have effects on its income statement. A financially independent central bank exhibits ...

  5. Gravity Independent Compressor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose to develop and demonstrate a small, gravity independent, vapor compression refrigeration system using a linear motor compressor which effectively...

  6. Crystal structure of tetra-kis-(μ3-2-{[1,1-bis-(hy-droxy-meth-yl)-2-oxidoeth-yl]imino-meth-yl}-6-meth-oxy-phenolato)tetra-kis-[aqua-copper(II)]: a redetermination at 200 K.

    Science.gov (United States)

    Buvaylo, Elena A; Vassilyeva, Olga Yu; Skelton, Brian W

    2015-10-01

    The crystal structure of the tetra-nuclear title compound, [Cu4(C12H15NO5)4(H2O)4], has been previously reported by Back, Oliveira, Canabarro & Iglesias [Z. Anorg. Allg. Chem. (2015), 641, 941-947], based on room-temperature data. In the previously published structure, no standard uncertainties are recorded for the deprotonated hy-droxy-methyl group and water mol-ecule O atoms coordinating to the metal atom indicating that they were not refined; furthermore, the H atoms of some OH groups and water mol-ecules have not been positioned accurately. Since the current structure was determined at a lower temperature, all atoms, including the H atoms of these hy-droxy groups and the water mol-ecule, have been determined more accurately resulting in improved standard uncertainties in the bond lengths and angles. Diffraction data were collected at 200 K, rather than the more usual 100 K, due to apparent disordering at lower temperatures. In addition, it is now possible to report intra- and inter-molecular O-H⋯O inter-actions. In the title complex molecule, which has crystallographic -4 symmetry, the Cu(II) ions are coordinated by the tridentate Schiff base ligands and water mol-ecules, forming a tetra-nuclear Cu4O4 cubane-like core. The Cu(II) ion adopts a CuNO5 elongated octa-hedral environment. The coordination environment of Cu(II) at 200 K displays a small contraction of the Cu-N/O bonds, compared with the room-temperature structure. In the crystal lattice, the neutral clusters are linked by inter-molecular O-H⋯O hydrogen bonds into a one-dimensional hydrogen-bonding network propagating along the b axis.

  7. Crystal structures of two nickel compounds comprising neutral Ni(II) hydrazone complexes and di-carb-oxy-lic acids.

    Science.gov (United States)

    Nakanishi, Takumi; Sato, Osamu

    2017-02-01

    Two isostructural Ni(II) compounds, bis-{N-[1-(pyridin-2-yl-κN)eth-ylidene]pyridine-4-carbohydrazonato-κ(2)N',O}nickel(II)-2,5-di-chloro-terephthalic acid (1/1), [Ni(C13H11N4O)2](C8H4Cl2O4), and bis-{N-[1-(pyridin-2-yl-κN)eth-ylidene]pyridine-4-carbohydrazonato-κ(2)N',O}nickel(II)-2,5-di-bromo-terephthalic acid (1/1), [Ni(C13H11N4O)2](C8H4Br2O4), were synthesized and their crystal structures determined. The pair of N,N',O-tridentate N-[1-(pyridin-2-yl-κN)eth-yl]pyridine-4-carbohydrazonate L ligands result in a cis-NiO2N4 octa-hedral coordination sphere for the metal ions. The asymmetric units consist of two half-mol-ecules of the di-carb-oxy-lic acids, which are completed by crystallographic inversion symmetry. In the respective crystals, the 2,5-di-chloro-terephthalic acid (H2Cl2TPA, 1-Cl) mol-ecules form zigzag hydrogen-bonded chains with the [Ni(L)2] mol-ecules, with the hydrogen-bond distances in 1-Br slightly longer than those in 1-Cl. The packing is consolidated by aromatic π-π stacking between the di-carb-oxy-lic acid mol-ecules and terminal pyridine rings in [Ni(L)2] and short halogen-halogen inter-actions are also observed. The qualitative prediction of the H-atom position from the C-N-C angles of the terminal pyridine rings in L and the C-O distances in the carboxyl groups show that 1-Cl and 1-Br are co-crystals rather than salts.

  8. Crystallographic groups and topology in Escher. (Spanish:Grupos cristalográficos y topología en Escher).

    OpenAIRE

    Montesinos Amilibia, José María

    2010-01-01

    In the late 19th century Fedorov, Schoenflies, and Barlow classified the seventeen wallpaper groups (two-dimensional crystallographic groups, five of them direct movements and twelve of them inverse movements) and the 320 three-dimensional crystallographic groups. In order to get the lists of groups, they all used the same geometric strategy: to combine all possible movements and study them case by case. Later on, Zassenhaus developed a purely algebraic algorithm which allowed him to u...

  9. Accounting for Independent Schools.

    Science.gov (United States)

    Sonenstein, Burton

    The diversity of independent schools in size, function, and mode of operation has resulted in a considerable variety of accounting principles and practices. This lack of uniformity has tended to make understanding, evaluation, and comparison of independent schools' financial statements a difficult and sometimes impossible task. This manual has…

  10. Independence of Internal Auditors.

    Science.gov (United States)

    Montondon, Lucille; Meixner, Wilda F.

    1993-01-01

    A survey of 288 college and university auditors investigated patterns in their appointment, reporting, and supervisory practices as indicators of independence and objectivity. Results indicate a weakness in the positioning of internal auditing within institutions, possibly compromising auditor independence. Because the auditing function is…

  11. Fostering Musical Independence

    Science.gov (United States)

    Shieh, Eric; Allsup, Randall Everett

    2016-01-01

    Musical independence has always been an essential aim of musical instruction. But this objective can refer to everything from high levels of musical expertise to more student choice in the classroom. While most conceptualizations of musical independence emphasize the demonstration of knowledge and skills within particular music traditions, this…

  12. On Background Independence

    CERN Document Server

    Anderson, Edward

    2013-01-01

    This paper concerns what Background Independence itself is (as opposed to some particular physical theory that is background independent). The notions presented mostly arose from a layer-by-layer analysis of the facets of the Problem of Time in Quantum Gravity. Part of this coincides with two relational postulates which are thus identified as classical precursors of two of the facets of the Problem of Time. These are furthemore tied to the forms of each of the GR Hamiltonian and momentum constraints. Other aspects of Background Independence include the algebraic closure of these constraints, expressing physics in terms of beables, foliation independence as implemented by refoliation invariance, the reconstruction of spacetime from space. The final picture is that Background Independence - a philosophically desirable and physically implementable feature for a theory to have - has the facets of the Problem of Time among its consequences. Thus these arise naturally and are problems to be resolved, as opposed to ...

  13. Probabilistic conditional independence structures

    CERN Document Server

    Studeny, Milan

    2005-01-01

    Probabilistic Conditional Independence Structures provides the mathematical description of probabilistic conditional independence structures; the author uses non-graphical methods of their description, and takes an algebraic approach.The monograph presents the methods of structural imsets and supermodular functions, and deals with independence implication and equivalence of structural imsets.Motivation, mathematical foundations and areas of application are included, and a rough overview of graphical methods is also given.In particular, the author has been careful to use suitable terminology, and presents the work so that it will be understood by both statisticians, and by researchers in artificial intelligence.The necessary elementary mathematical notions are recalled in an appendix.

  14. Self-assembled ultra-nanocrystalline silicon films with preferred crystallographic orientation for solar cell applications

    Science.gov (United States)

    Banerjee, Amit; Das, Debajyoti

    2015-03-01

    Using low-pressure planar inductively coupled plasma CVD at 87% H2-dilution to the SiH4 plasma, nc-Si:H films are prepared that possess preferential growth along crystallographic orientation with I220/I111 > 1.2, bonded H-content of ∼5.5 at.%, a low microstructure factor of ∼0.56, along with a reasonably high σD ∼ 5.2 × 10-4 S cm-1, ΔE ∼ 143 meV and σPh ∼ 1.4 × 10-3 S cm-1. The growth of the nc-Si:H network has been optimized to a moderately high nanocrystallinity (∼68%), with an average grain size of ∼8 nm. The overall network comprises a significant fraction of ultra-nanocrystalline component, Xunc/Xnc ∼ 0.47, which are dominantly inhabited by the thermodynamically preferred crystallographic orientation that provides convenient electrical transport perpendicular to the film surface and subsequently could facilitate photovoltaic performance. The cross-sectional view of the fracture surface demonstrates columnar structures, closely correlated to the favored growth of the nanocrystallites along crystallographic orientation that retains direction perpendicular to the substrate surface. The underlying phenomena could be demonstrated as a consequence of preferential growth induced by high atomic H density present in the planar inductively coupled SiH4 plasma obtained via much lower H2-dilution compared to that realized in conventional capacitively coupled plasma-CVD. The nc-Si:H films with precise material properties as well as the allied low-pressure ICP-CVD growth process could be of significant use in further progress of nc-Si solar cells.

  15. Trapping of Oxygen Vacancies at Crystallographic Shear Planes in Acceptor-Doped Pb-Based Ferroelectrics.

    Science.gov (United States)

    Batuk, Dmitry; Batuk, Maria; Tsirlin, Alexander A; Hadermann, Joke; Abakumov, Artem M

    2015-12-01

    The defect chemistry of the ferroelectric material PbTiO3 after doping with Fe(III) acceptor ions is reported. Using advanced transmission electron microscopy and powder X-ray and neutron diffraction, we demonstrate that even at concentrations as low as circa 1.7% (material composition approximately ABO2.95), the oxygen vacancies are trapped into extended planar defects, specifically crystallographic shear planes. We investigate the evolution of these defects upon doping and unravel their detailed atomic structure using the formalism of superspace crystallography, thus unveiling their role in nonstoichiometry in the Pb-based perovskites.

  16. Crystallographic dependence of photocatalytic activity of WO3 thin films prepared by molecular beam epitaxy.

    Science.gov (United States)

    Li, Guoqiang; Varga, Tamas; Yan, Pengfei; Wang, Zhiguo; Wang, Chongmin; Chambers, Scott A; Du, Yingge

    2015-06-21

    We investigated the impact of crystallographic orientation on the photocatalytic activity of single crystalline WO3 thin films prepared by molecular beam epitaxy on the photodegradation of rhodamine B (RhB). A clear effect is observed, with (111) being the most reactive surface, followed by (110) and (001). Photoreactivity is directly correlated with the surface free energy determined by density functional theory calculations. The RhB photodegradation mechanism is found to involve hydroxyl radicals in solution formed from photo-generated holes and differs from previous studies performed on nanoparticles and composites.

  17. Regularities of crystallographic texture formation in cladding tubes from Zr-based alloys during their production

    Science.gov (United States)

    Isaenkova, M.; Perlovich, Yu; Fesenko, V.

    2016-04-01

    This paper summarizes researches of the authors, which are directed on the development of the methodological basis of X-ray studies in the materials science of zirconium and on the systematization of new experimental results obtained using developed methods. The paper describes regularities of the formation of the crystallographic texture and the substructure inhomogeneity of cladding tubes from zirconium alloys at various stages of their manufacturing, i.e. during hot and cold deformation, recrystallization, phase transformations and interactions of the above processes.

  18. (Fundamental studies of new magnetic heterostructures: Their growth, crystallographic structure, magnetic and electronic properties)

    Energy Technology Data Exchange (ETDEWEB)

    Onellion, M. (Wisconsin Univ., Madison, WI (USA). Dept. of Physics); Dowben, P.A. (Syracuse Univ., NY (USA). Dept. of Physics)

    1990-01-01

    As part of our request for renewal of our grant, we include this progress report on the significant results obtained under grant number FG02-89ER45319, Fundamental Studies of New Magnetic Heterostructures: Their Growth, Crystallographic Structure, Magnetic and Electronic Properties,'' since the inception of the grant. The results include the scientific accomplishments, the instrumentation developed, and the technological applications of our work. Each area is discussed separately and an initial summary of all areas is provided before the detailed discussion.

  19. Use of Bayesian Inference in Crystallographic Structure Refinement via Full Diffraction Profile Analysis

    Science.gov (United States)

    Fancher, Chris M.; Han, Zhen; Levin, Igor; Page, Katharine; Reich, Brian J.; Smith, Ralph C.; Wilson, Alyson G.; Jones, Jacob L.

    2016-01-01

    A Bayesian inference method for refining crystallographic structures is presented. The distribution of model parameters is stochastically sampled using Markov chain Monte Carlo. Posterior probability distributions are constructed for all model parameters to properly quantify uncertainty by appropriately modeling the heteroskedasticity and correlation of the error structure. The proposed method is demonstrated by analyzing a National Institute of Standards and Technology silicon standard reference material. The results obtained by Bayesian inference are compared with those determined by Rietveld refinement. Posterior probability distributions of model parameters provide both estimates and uncertainties. The new method better estimates the true uncertainties in the model as compared to the Rietveld method. PMID:27550221

  20. Morphological and crystallographic evolution of bainite transformation in Fe-0.15C binary alloy.

    Science.gov (United States)

    Zhang, Di; Terasaki, Hidenori; Komizo, Yuichi

    2010-01-01

    In this article, an in situ observation method, combining laser scanning confocal microscopy and electron backscattering diffraction, was used to investigate the morphological and crystallographic evolution of bainite transformation in a Fe-0.15C binary alloy. The nucleation at a grain boundary and inclusions, sympathetic nucleation, and impingement event of bainitic ferrite were directly shown in real time. The variant evolution during bainite transformation and misorientation between bainitic ferrites were clarified. Strong variant selection was observed during sympathetic nucleation. (c) 2009 Wiley-Liss, Inc.

  1. N-(3-Chloro-4-methyl-phen-yl)succinamic acid.

    Science.gov (United States)

    Chaithanya, U; Foro, Sabine; Gowda, B Thimme

    2012-03-01

    In the crystal structure of the title compound, C(11)H(12)ClNO(3), the asymmetric unit contains two independent mol-ecules. The N-H bond in the amide segment is anti to the meta-Cl atom in the benzene ring, in both molecules. The amide and carboxyl C=O bonds are also anti to each other and anti to the H atoms on the adjacent -CH(2) groups. Furthermore, the C=O and O-H bonds of the acid group are in syn positions with respect to each other. The dihedral angles between the benzene ring and the amide group are 40.6 (2) and 44.9 (3)° in the two independent molecules. In the crystal, mol-ecules are packed into sheets parallel to the (11-3) plane through O-H⋯O and N-H⋯O hydrogen bonds.

  2. Independent technical review, handbook

    Energy Technology Data Exchange (ETDEWEB)

    1994-02-01

    Purpose Provide an independent engineering review of the major projects being funded by the Department of Energy, Office of Environmental Restoration and Waste Management. The independent engineering review will address questions of whether the engineering practice is sufficiently developed to a point where a major project can be executed without significant technical problems. The independent review will focus on questions related to: (1) Adequacy of development of the technical base of understanding; (2) Status of development and availability of technology among the various alternatives; (3) Status and availability of the industrial infrastructure to support project design, equipment fabrication, facility construction, and process and program/project operation; (4) Adequacy of the design effort to provide a sound foundation to support execution of project; (5) Ability of the organization to fully integrate the system, and direct, manage, and control the execution of a complex major project.

  3. Distro’: Independent Creativity for Independent Industr

    Directory of Open Access Journals (Sweden)

    Wiwik Sri Wulandari

    2014-11-01

    Full Text Available To shortened this introduction, ‘Distro’ is one of cultural phenomenon in theyoung generation nowadays. The word of ‘Distro’ is the shortened of DistributionOutlet. The phenomenon of ‘Distro’ has been some kind of new trends inproducing and distributing creative design products of goods amongst theyoungsters independently, in an independence industry that open for challengingand competitiveness for everyone. This field research has been done in the city ofYogyakarta, reknown as the second city in creative design products after the cityof Bandung. Yogyakarta is welknown as the students’ city as well as the capital cityof culture of Indonesia. As a students’ city it is normal that Yogyakarta is growingin numbers of young people who pursued to study here and enriched the cultureof the city to become more multicultural and the varieties of pluralism as well.This sociocultural phenomenon not only brought some dynamic changing tosociety, economy and cultural life of the city, but also social problems that needsto be overcome. My first research question then is about how the existence of‘Distro’ in Yogyakarta can be a positive answer for social problems that may arisesfrom the hegemony of globalization markets domestically? My second questionis how the creative product designs are being made and distributed creatively inindependent industry? Lastly, my third question is dealling with the genres ofthe design products and how it can be a new trend in art expression? ‘Distro’ is aproduct of culture and it is also creating cultural change in some aspects of the lifeof the youngsters who are ‘Distro’ enthusiasts. ‘Distro’ phenomenon basically is anoffensive to the hegemony of internationally branded product design which turnsto become more over-dominated to the domestic markets and industry and thus,‘Distro’ has the spirit of survival whilts at the same time producing opportunity ofenterpreneurship

  4. Symmetry implies independence

    CERN Document Server

    Renner, R

    2007-01-01

    Given a quantum system consisting of many parts, we show that symmetry of the system's state, i.e., invariance under swappings of the subsystems, implies that almost all of its parts are virtually identical and independent of each other. This result generalises de Finetti's classical representation theorem for infinitely exchangeable sequences of random variables as well as its quantum-mechanical analogue. It has applications in various areas of physics as well as information theory and cryptography. For example, in experimental physics, one typically collects data by running a certain experiment many times, assuming that the individual runs are mutually independent. Our result can be used to justify this assumption.

  5. Magnetic transition temperatures follow crystallographic symmetry in samarium under high-pressures and low-temperatures

    Science.gov (United States)

    Johnson, Craig R.; Tsoi, Georgiy M.; Vohra, Yogesh K.

    2017-02-01

    Magnetic ordering temperatures in rare earth metal samarium (Sm) have been studied using an ultrasensitive electrical transport measurement technique in a designer diamond anvil cell to high-pressure up to 47 GPa and low-temperature to 10 K. The two magnetic transitions at 106 K and 14 K in the α-Sm phase, attributed to antiferromagnetic ordering on hexagonal and cubic layers respectively, collapse in to one magnetic transition near 10 GPa when Sm assumes a double hexagonal close packed (dhcp) phase. On further increase in pressure above 34 GPa, the magnetic transitions split again as Sm adopts a hexagonal-hP3 structure indicating different magnetic transition temperatures for different crystallographic sites. A model for magnetic ordering for the hexagonal-hP3 phase in samarium has been proposed based on the experimental data. The magnetic transition temperatures closely follow the crystallographic symmetry during α-Sm  →  dhcp  →  fcc/dist.fcc  →  hP3 structure sequence at high-pressures and low-temperatures.

  6. Erbium-ion implantation into various crystallographic cuts of Al2O3

    Science.gov (United States)

    Nekvindova, P.; Mackova, A.; Malinsky, P.; Cajzl, J.; Svecova, B.; Oswald, J.; Wilhelm, R. A.

    2015-12-01

    This paper reports on the importance of crystallographic cuts with a different orientation on the luminescent properties and structural changes of Al2O3 implanted with Er+ ions at 190 keV and with a fluence of 1.0 × 1016 cm-2. Post-implantation annealing at 1000 °C in oxygen atmosphere was also done. The chemical compositions and erbium concentration-depth profiles of implanted layers were studied by Rutherford Backscattering Spectrometry (RBS) and compared to SRIM simulations. The same value of the maximum erbium concentration (up to 2 at.%) was observed at a depth of about 40 nm for all crystallographic cuts. The structural properties of the prepared layers were characterised by RBS/channelling. The relative amount of disordered atoms of 70-80% was observed in the prepared implanted layers and discussed for various cuts. It has been found that erbium is positioned randomly in the Al2O3 crystalline matrix, and no preferential positions appeared even after the annealing procedure. Erbium luminescence properties were measured in the wavelength range of 1440-1650 nm for all samples. As-implanted Al2O3 samples had a significant luminescence band at 1530 nm. The best luminescence was repeatedly observed in the cut of Al2O3. The annealing procedure significantly improved the luminescent properties.

  7. Crystallographic structure of Ni-Co coating on the affinity adsorption of histidine-tagged protein.

    Science.gov (United States)

    Chang, Yaw-Jen; Chen, Sheng-Zheng; Ho, Ching-Yuan

    2015-04-01

    The principle of immobilized metal affinity chromatography (IMAC) has been recently implemented for protein microarrays for the study of protein abundance and function. Ni-Co film fabricated by electrodeposition is a novel microarray surface in an alloy type for immobilizing histidine-tagged proteins based on IMAC. In this paper, the effects of crystallographic structures and surface properties of Ni-Co coatings, with and without the annealing process, on the immobilization of histidine-tagged proteins were systematically investigated. The experimental results reveal that the stronger hcp texture, due to a higher Co content, results in better affinity adsorption for histidine-tagged biotin. Nevertheless, the allotropic phase transformation from hcp to fcc, due to the annealing process, leads to the decrease of affinity adsorption. The wettability property and the surface roughness of Ni-Co coating are, however, not important factors. Obviously, the crystallographic structure of Ni-Co coating is the dominant factor for the specific affinity adsorption of histidine-tagged protein.

  8. Crystallographic superstructure in R2PdSi3 compounds (R=heavy rare earth)

    Science.gov (United States)

    Tang, Fei; Frontzek, Matthias; Dshemuchadse, Julia; Leisegang, Tilmann; Zschornak, Matthias; Mietrach, Robert; Hoffmann, Jens-Uwe; Löser, Wolfgang; Gemming, Sibylle; Meyer, Dirk C.; Loewenhaupt, Michael

    2011-09-01

    The R2PdSi3 intermetallic compounds have been reported to crystallize in a hexagonal AlB2-derived structure, with the rare earth atoms on the Al sites and Pd and Si atoms randomly distributed on the B sites. However, the intricate magnetic properties observed in the series of compounds have always suggested complications to the assumed structure. To clarify the situation, x-ray and neutron diffraction measurements were performed on the heavy rare earth compounds with R=Gd, Tb, Dy, Ho, Er, Tm, which revealed the existence of a crystallographic superstructure. The superstructure features a doubled unit cell in the hexagonal basal plane and an octuplication along the perpendicular c direction with respect to the primitive cell. No structural transition was observed between 300 and 1.5 K. Extended x-ray absorption fine structure (EXAFS) analysis as well as density functional theory (DFT) calculations were utilized to investigate the local environments of the respective atoms. In this paper the various experimental results will be presented and it will be shown that the superstructure is mainly due to the Pd-Si order on the B sites. A structure model will be proposed to fully describe the superstructure of Pd-Si order in R2PdSi3. The connection between the crystallographic superstructure and the magnetic properties will be discussed in the framework of the presented model.

  9. Reaction temperature variations on the crystallographic state of spinel cobalt aluminate.

    Science.gov (United States)

    Taguchi, Minori; Nakane, Takayuki; Hashi, Kenjiro; Ohki, Shinobu; Shimizu, Tadashi; Sakka, Yoshio; Matsushita, Akiyuki; Abe, Hiroya; Funazukuri, Toshitaka; Naka, Takashi

    2013-05-21

    In this study, we report a rapid and simple technique for obtaining cobalt aluminate having a spinel structure. The products were prepared from a hydroxide precursor synthesized by coprecipitation of cobalt (Co(2+)) and aluminum (Al(3+)) nitrates with an alkaline solution. The chosen precursor enabled low temperature fabrication of cobalt aluminate with a spinel structure by sintering it for 2 hours at low temperatures (>400 °C). Crystallographic and thermal analyses suggest that the low-temperature-sintered products contain Co(3+) ions stabilized by chemisorbed water and/or hydroxide groups, which was not observed for products sintered at temperatures higher than 1000 °C. The color of the products turned from clear blue (Thenard's blue) to dark green when sintering temperatures were below 1000 °C. Magnetic quantities, Curie constants, and Weiss temperatures show a strong dependence on the sintering temperature. These findings suggest that there are mixed valent states, i.e. Co(2+) and Co(3+), and unique cation distributions at the different crystallographic sites in the spinel structure, especially in the products sintered at lower temperatures.

  10. Synthesis of crystallographically oriented olivine aggregates using colloidal processing in a strong magnetic field

    Science.gov (United States)

    Koizumi, Sanae; Suzuki, Tohru S.; Sakka, Yoshio; Yabe, Kosuke; Hiraga, Takehiko

    2016-11-01

    This study develops a fabrication technique to obtain Fe-free and Fe-bearing (Fe:Mg = 1:9) olivine aggregates not only with high density and fine grain size but with crystallographic preferred orientation (CPO). A magnetic field (≤12 T) is applied to synthetic, fine-grained ( 120 nm), olivine particles dispersed in solvent. The alignment of certain crystallographic axes of the particles with respect to a magnetic direction is anticipated due to magnetic anisotropy of olivine. The dispersed particles are gradually consolidated on a porous alumina mold covered with a solid-liquid separation filter during drainage of the solvent. The resultant aligned consolidated aggregate is then isostatically pressed and vacuum sintered. We find that (1) preparation of fully reacted olivine particles, with less propensity to coalesce; (2) preparation of a suspension with highly dispersed particles; and (3) application of a certain strength of the magnetic field are essential to obtain well-sintered and well-aligned aggregates. High density (i.e., olivine aggregates were successfully synthesized with uniaxially aligned a- and c-axes, respectively. Attempts to uniaxially align the magnetization hard axis and to triaxially align Fe-bearing olivine by rotating the suspension in the magnetic field succeeded in obtaining weakly developed CPO aggregates.

  11. Crystallographic and electronic properties of AlCrN films that absorb visible light

    Science.gov (United States)

    Tatemizo, N.; Imada, S.; Miura, Y.; Nishio, K.; Isshiki, T.

    2017-05-01

    We investigate the crystallographic and electronic properties of wurtzite Cr-doped AlN (AlCrN) films (Cr ≤12.0%) that absorb visible light. We confirmed that the films consist of wurtzite columnar single crystals that are densely packed, c-axis oriented, and exhibit a random rotation along the a-axis in plane by using transmission electron microscopy. The oxidation state of Cr was found to be 3+ using Cr K-edge X-ray absorption near edge structure, which implies that Cr can be a substitute for Al3+ in AlN. The first nearest neighbor distances estimated using Cr K-edge extended X-ray absorption fine structure (EXAFS) were found to be nearly isotropic for incident light with electric fields that are parallel and perpendicular to the plane. The results of ab initio lattice relaxation calculations for the model of wurtzite Al1-xCrxN supercell where Cr replaces Al support the EXAFS results. The calculations for the model showed that additional energy bands are formed in the band gap of AlN, in which the Fermi energy (EF) is present. As expected from the calculation results, the electrical conductivity increases with increase in the Cr concentration, implying that the density of states at EF increases monotonically. From these results, we can conclude that AlCrN films are an intermediate band material with respect to their crystallographic and electric properties.

  12. Determination of precise crystallographic directions for mask alignment in wet bulk micromachining for MEMS

    Science.gov (United States)

    Singh, Sajal Sagar; Pal, Prem; Pandey, Ashok Kumar; Xing, Yan; Sato, Kazuo

    2016-12-01

    In wet bulk micromachining, the etching characteristics are orientation dependent. As a result, prolonged etching of mask openings of any geometric shape on both Si{100} and Si{110} wafers results in a structure defined by the slowest etching planes. In order to fabricate microstructures with high dimensional accuracy, it is vital to align the mask edges along the crystal directions comprising of these slowest etching planes. Thus, precise alignment of mask edges is important in micro/nano fabrication. As a result, the determination of accurate crystal directions is of utmost importance and is in fact the first step to ensure dimensionally accurate microstructures for improved performance. In this review article, we have presented a comprehensive analysis of different techniques to precisely determine the crystallographic directions. We have covered various techniques proposed in the span of more than two decades to determine the crystallographic directions on both Si{100} and Si{110} wafers. Apart from a detailed discussion of each technique along with their design and implementation, we have provided a critical analysis of the associated constraints, benefits and shortcomings. We have also summed up the critical aspects of each technique and presented in a tabular format for easy reference for readers. This review article comprises of an exhaustive discussion and is a handy reference for researchers who are new in the field of wet anisotropic etching or who want to get abreast with the techniques of determination of crystal directions.

  13. Conformation-changing aggregation in hydroxyacetone: a combined low-temperature FTIR, jet, and crystallographic study.

    Science.gov (United States)

    Sharma, Archna; Reva, Igor; Fausto, Rui; Hesse, Susanne; Xue, Zhifeng; Suhm, Martin A; Nayak, Susanta K; Sathishkumar, Ranganthan; Pal, Rumpa; Row, Tayur N Guru

    2011-12-21

    Aggregation in hydroxyacetone (HA) is studied using low-temperature FTIR, supersonic jet expansion, and X-ray crystallographic (in situ cryocrystallization) techniques. Along with quantum chemical methods (MP2 and DFT), the experiments unravel the conformational preferences of HA upon aggregation to dimers and oligomers. The O-H···O═C intramolecular hydrogen bond present in the gas-phase monomer partially opens upon aggregation in supersonic expansions, giving rise to intermolecular cooperatively enhanced O-H···O-H hydrogen bonds in competition with isolated O-H···O═C hydrogen bonds. On the other hand, low-temperature IR studies on the neat solid and X-ray crystallographic data reveal that HA undergoes profound conformational changes upon crystallization, with the HOCC dihedral angle changing from ~0° in the gas phase to ~180° in the crystalline phase, hence giving rise to a completely new conformation. These conclusions are supported by theoretical calculations performed on the geometry derived from the crystalline phase. © 2011 American Chemical Society

  14. Acanthamoeba polyphaga mimivirus NDK: preliminary crystallographic analysis of the first viral nucleoside diphosphate kinase

    Energy Technology Data Exchange (ETDEWEB)

    Jeudy, Sandra [Information Génomique et Structurale, CNRS UPR 2589, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20 (France); Coutard, Bruno [Architecture et Fonction des Macromolecules Biologiques, CNRS UMR 6098, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20 (France); Lebrun, Régine [IBSM, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20 (France); Abergel, Chantal, E-mail: chantal.abergel@igs.cnrs-mrs.fr [Information Génomique et Structurale, CNRS UPR 2589, 31 Chemin Joseph Aiguier, 13402 Marseille CEDEX 20 (France)

    2005-06-01

    A. polyphaga mimivirus, the largest known double-stranded DNA virus, is the first virus to exhibit a nucleoside diphosphate kinase gene. The expression and crystallization of the viral NDK are reported. The complete sequence of the largest known double-stranded DNA virus, Acanthamoeba polyphaga mimivirus, has recently been determined [Raoult et al. (2004 ▶), Science, 306, 1344–1350] and revealed numerous genes not expected to be found in a virus. A comprehensive structural and functional study of these gene products was initiated [Abergel et al. (2005 ▶), Acta Cryst. F61, 212–215] both to better understand their role in the virus physiology and to obtain some clues to the origin of DNA viruses. Here, the preliminary crystallographic analysis of the viral nucleoside diphosphate kinase protein is reported. The crystal belongs to the cubic space group P2{sub 1}3, with unit-cell parameter 99.425 Å. The self-rotation function confirms that there are two monomers per asymmetric unit related by a twofold non-crystallographic axis and that the unit cell thus contains four biological entities.

  15. The fourth crystallographic closest packing unveiled in the gold nanocluster crystal

    Science.gov (United States)

    Gan, Zibao; Chen, Jishi; Wang, Juan; Wang, Chengming; Li, Man-Bo; Yao, Chuanhao; Zhuang, Shengli; Xu, An; Li, Lingling; Wu, Zhikun

    2017-03-01

    Metal nanoclusters have recently attracted extensive interest not only for fundamental scientific research, but also for practical applications. For fundamental scientific research, it is of major importance to explore the internal structure and crystallographic arrangement. Herein, we synthesize a gold nanocluster whose composition is determined to be Au60S6(SCH2Ph)36 by using electrospray ionization mass spectrometry and single crystal X-ray crystallography (SCXC). SCXC also reveals that Au60S6(SCH2Ph)36 consists of a fcc-like Au20 kernel protected by a pair of giant Au20S3(SCH2Ph)18 staple motifs, which contain 6 tetrahedral-coordinate μ4-S atoms not previously reported in the Au-S interface. Importantly, the fourth crystallographic closest-packed pattern, termed 6H left-handed helical (6HLH) arrangement, which results in the distinct loss of solid photoluminescence of amorphous Au60S6(SCH2Ph)36, is found in the crystals of Au60S6(SCH2Ph)36. The solvent-polarity-dependent solution photoluminescence is also demonstrated. Overall, this work provides important insights about the structure, Au-S bonding and solid photoluminescence of gold nanoclusters.

  16. Evaluating Free Energies of Binding and Conservation of Crystallographic Waters Using SZMAP.

    Science.gov (United States)

    Bayden, Alexander S; Moustakas, Demetri T; Joseph-McCarthy, Diane; Lamb, Michelle L

    2015-08-24

    The SZMAP method computes binding free energies and the corresponding thermodynamic components for water molecules in the binding site of a protein structure [ SZMAP, 1.0.0 ; OpenEye Scientific Software Inc. : Santa Fe, NM, USA , 2011 ]. In this work, the ability of SZMAP to predict water structure and thermodynamic stability is examined for the X-ray crystal structures of a series of protein-ligand complexes. SZMAP results correlate with higher-level replica exchange thermodynamic integration double decoupling calculations of the absolute free energy of bound waters in the test set complexes. In addition, SZMAP calculations show good agreement with experimental data in terms of water conservation (across multiple crystal structures) and B-factors over a subset of the test set. In particular, the SZMAP neutral entropy difference term calculated at crystallographic water positions within each of the complex structures correlates well with whether that crystallographic water is conserved or displaceable. Furthermore, the calculated entropy of the water probe relative to the continuum shows a significant degree of correlation with the B-factors associated with the oxygen atoms of the water molecules. Taken together, these results indicate that SZMAP is capable of quantitatively predicting water positions and their energetics and is potentially a useful tool for determining which waters to attempt to displace, maintain, or build in through water-mediated interactions when evolving a lead series during a drug discovery program.

  17. Development of Microstructure and Crystallographic Texture in a Double-Sided Friction Stir Welded Microalloyed Steel

    Science.gov (United States)

    Rahimi, S.; Wynne, B. P.; Baker, T. N.

    2017-01-01

    The evolution of microstructure and crystallographic texture has been investigated in double-sided friction stir welded microalloyed steel, using electron backscatter diffraction (EBSD). The microstructure analyses show that the center of stirred zone reached a temperature between Ac1 and Ac3 during FSW, resulting in a dual-phase austenitic/ ferritic microstructure. The temperatures in the thermo-mechanically affected zone and the overlapped area between the first and second weld pass did not exceed the Ac1. The shear generated by the rotation probe occurs in austenitic/ferritic phase field where the austenite portion of the microstructure is transformed to a bainitic ferrite, on cooling. Analysis of crystallographic textures with regard to shear flow lines generated by the probe tool shows the dominance of simple shear components across the whole weld. The austenite texture at Ac1 - Ac3 is dominated by the B { {1bar{1}2} }stirred zone and the ferrites in the thermo-mechanically affected zones and the overlapped area underwent shear deformation with textures dominated by the D1 { {bar{1}bar{1}2} }weld pass. This is due to continuous dynamic strain-induced recrystallization as a result of simultaneous severe shear deformation and drastic undercooling.

  18. Enhancing nanoscale SEM image segmentation and reconstruction with crystallographic orientation data and machine learning

    Energy Technology Data Exchange (ETDEWEB)

    Converse, Matthew I., E-mail: mconverse85@yahoo.com; Fullwood, David T.

    2013-09-15

    Current methods of image segmentation and reconstructions from scanning electron micrographs can be inadequate for resolving nanoscale gaps in composite materials (1–20 nm). Such information is critical to both accurate material characterizations and models of piezoresistive response. The current work proposes the use of crystallographic orientation data and machine learning for enhancing this process. It is first shown how a machine learning algorithm can be used to predict the connectivity of nanoscale grains in a Nickel nanostrand/epoxy composite. This results in 71.9% accuracy for a 2D algorithm and 62.4% accuracy in 3D. Finally, it is demonstrated how these algorithms can be used to predict the location of gaps between distinct nanostrands — gaps which would otherwise not be detected with the sole use of a scanning electron microscope. - Highlights: • A method is proposed for enhancing the segmentation/reconstruction of SEM images. • 3D crystallographic orientation data from a nickel nanocomposite is collected. • A machine learning algorithm is used to detect trends in adjacent grains. • This algorithm is then applied to predict likely regions of nanoscale gaps. • These gaps would otherwise be unresolved with the sole use of an SEM.

  19. CRYSNET manual. Informal report. [Hardware and software of crystallographic computing network

    Energy Technology Data Exchange (ETDEWEB)

    None,

    1976-07-01

    This manual describes the hardware and software which together make up the crystallographic computing network (CRYSNET). The manual is intended as a users' guide and also provides general information for persons without any experience with the system. CRYSNET is a network of intelligent remote graphics terminals that are used to communicate with the CDC Cyber 70/76 computing system at the Brookhaven National Laboratory (BNL) Central Scientific Computing Facility. Terminals are in active use by four research groups in the field of crystallography. A protein data bank has been established at BNL to store in machine-readable form atomic coordinates and other crystallographic data for macromolecules. The bank currently includes data for more than 20 proteins. This structural information can be accessed at BNL directly by the CRYSNET graphics terminals. More than two years of experience has been accumulated with CRYSNET. During this period, it has been demonstrated that the terminals, which provide access to a large, fast third-generation computer, plus stand-alone interactive graphics capability, are useful for computations in crystallography, and in a variety of other applications as well. The terminal hardware, the actual operations of the terminals, and the operations of the BNL Central Facility are described in some detail, and documentation of the terminal and central-site software is given. (RWR)

  20. The Structural Biology Center 19ID undulator beamline: facility specifications and protein crystallographic results.

    Science.gov (United States)

    Rosenbaum, Gerd; Alkire, Randy W; Evans, Gwyndaf; Rotella, Frank J; Lazarski, Krzystof; Zhang, Rong Guang; Ginell, Stephan L; Duke, Norma; Naday, Istvan; Lazarz, Jack; Molitsky, Michael J; Keefe, Lisa; Gonczy, John; Rock, Larry; Sanishvili, Ruslan; Walsh, Martin A; Westbrook, Edwin; Joachimiak, Andrzej

    2006-01-01

    The 19ID undulator beamline of the Structure Biology Center has been designed and built to take full advantage of the high flux, brilliance and quality of X-ray beams delivered by the Advanced Photon Source. The beamline optics are capable of delivering monochromatic X-rays with photon energies from 3.5 to 20 keV (3.5-0.6 A wavelength) with fluxes up to 8-18 x 10(12) photons s(-1) (depending on photon energy) onto cryogenically cooled crystal samples. The size of the beam (full width at half-maximum) at the sample position can be varied from 2.2 mm x 1.0 mm (horizontal x vertical, unfocused) to 0.083 mm x 0.020 mm in its fully focused configuration. Specimen-to-detector distances of between 100 mm and 1500 mm can be used. The high flexibility, inherent in the design of the optics, coupled with a kappa-geometry goniometer and beamline control software allows optimal strategies to be adopted in protein crystallographic experiments, thus maximizing the chances of their success. A large-area mosaic 3 x 3 CCD detector allows high-quality diffraction data to be measured rapidly to the crystal diffraction limits. The beamline layout and the X-ray optical and endstation components are described in detail, and the results of representative crystallographic experiments are presented.

  1. Mode decomposition based on crystallographic symmetry in the band-unfolding method

    Science.gov (United States)

    Ikeda, Yuji; Carreras, Abel; Seko, Atsuto; Togo, Atsushi; Tanaka, Isao

    2017-01-01

    The band-unfolding method is widely used to calculate the effective band structures of a disordered system from its supercell model. The unfolded band structures show the crystallographic symmetry of the underlying structure, where the difference of chemical components and the local atomic relaxation are ignored. However, it has still been difficult to decompose the unfolded band structures into the modes based on the crystallographic symmetry of the underlying structure, and therefore detailed analyses of the unfolded band structures have been restricted. In this study, a procedure to decompose the unfolded band structures according to the small representations (SRs) of the little groups is developed. The decomposition is performed using the projection operators for SRs derived from the group representation theory. The current method is employed to investigate the phonon band structure of disordered face-centered-cubic Cu0.75Au0.25 , which has large variations of atomic masses and force constants among the atomic sites due to the chemical disorder. In the unfolded phonon band structure, several peculiar behaviors such as discontinuous and split branches are found in the decomposed modes corresponding to specific SRs. They are found to occur because different combinations of the chemical elements contribute to different regions of frequency.

  2. The Critical Independence Number and an Independence Decomposition

    CERN Document Server

    Larson, Craig Eric

    2009-01-01

    An independent set $I_c$ is a \\textit{critical independent set} if $|I_c| - |N(I_c)| \\geq |J| - |N(J)|$, for any independent set $J$. The \\textit{critical independence number} of a graph is the cardinality of a maximum critical independent set. This number is a lower bound for the independence number and can be computed in polynomial-time. Any graph can be decomposed into two subgraphs where the independence number of one subgraph equals its critical independence number, where the critical independence number of the other subgraph is zero, and where the sum of the independence numbers of the subgraphs is the independence number of the graph. A proof of a conjecture of Graffiti.pc yields a new characterization of K\\"{o}nig-Egervary graphs: these are exactly the graphs whose independence and critical independence numbers are equal.

  3. Independent School Administration.

    Science.gov (United States)

    Springer, E. Laurence

    This book deals with the management of privately supported schools and offers guidelines on how these schools might be operated more effectively and economically. The discussions and conclusions are based on observations and data from case studies of independent school operations. The subjects discussed include the role and organization of…

  4. Independence in appearance

    DEFF Research Database (Denmark)

    Warming-Rasmussen, Bent; Quick, Reiner; Liempd, Dennis van

    2011-01-01

    article presents research contributions to the question whether the auditor is to continue to provide both audit and non-audit services (NAS) to an audit client. Research results show that this double function for the same audit client is a problem for stakeholders' confidence in auditor independence...

  5. Methyl 2-(3a,8a-dimethyl-4-oxodeca-hydro-azulen-6-yl)acrylate.

    Science.gov (United States)

    Tebbaa, Mohamed; Benharref, Ahmed; Berraho, Moha; Daran, Jean Claude; Akssira, Mohamed; Elhakmaoui, Ahmed

    2011-08-01

    The title compound, C(16)H(24)O(3), was synthesized from ilicic acid, which was isolated from the aerial part of Inula viscosa- (L) Aiton [or Dittrichia viscosa- (L) Greuter]. The asymmetric unit contains two independent mol-ecules, in each of which the seven-membered ring shows a chair conformation, whereas the five-membered ring presents disorder. In the two molecules, three C atoms in the five-membered ring are disordered over two positions with site-occupancy factors of 0.53/0.47 and 0.83/0.17. The dihedral angle between the two rings is different in the two mol-ecules [31.7 (3) and 47.7 (7)°]. The crystal structure is stabilized by weak inter-molecular C-H⋯O hydrogen-bond inter-actions.

  6. 1-[(1S,6R,7S,9R)-8,8-Di-bromo-5,5,9-tri-methyl-tri-cyclo-[4.4.0.1(7,9)]decan-1-yl]ethanone.

    Science.gov (United States)

    Zaki, Mohamed; Benharref, Ahmed; El Ammari, Lahcen; Saadi, Mohamed; Berraho, Moha

    2014-04-01

    The title compound, C16H24Br2O, was synthesized by three steps from β-himachalene (3,5,5,9-tetra-methyl-2,4a,5,6,7,8-hexa-hydro-1H-benzo-cyclo-heptene), which was isolated from essential oil of the Atlas cedar cedrus atlantica. The asymmetric unit contains two independent mol-ecules with almost identical conformations. Each mol-ecule is built up from two fused six-membered rings, one having a chair conformation and the other a boat conformation, and an additional three-membered ring arising from the reaction of himachalene with di-bromo-carbene. In the crystal, there are no significant intermolecular interactions present. The absolute structure of the title compound was confirmed by resonance scattering.

  7. 1-Isopropyl-4,7-dimethyl-2,8-dinitro-naphthalene.

    Science.gov (United States)

    Chakkar, Mouna; Oughris, Najia; Benharref, Ahmed; Daran, Jean-Claude; Berraho, Moha

    2012-06-01

    The title compound, C(15)H(16)N(2)O(4), was synthesized from a mixture of α-himachalene (2-methyl-ene-6,6,9-trimethyl-bicyclo-[5.4.O(1,7)]undec-8-ene) and β-himachalene (2,6,6,9-tetra-methyl-bicyclo-[5.4.0(1,7)]undeca-1,8-diene) which were isolated from an oil of the Atlas cedar (Cedrus atlantica). The asymmetric unit contains two independent mol-ecules. In each of the two mol-ecules, two O atoms of one nitro group are disordered over two sets of sites with site-occupancy factors of 0.636 (5):0.364 (5) and 0.832 (5):0.168 (5). The crystal structure features weak C-H⋯O hydrogen bonds.

  8. Quantum independent increment processes

    CERN Document Server

    Franz, Uwe

    2005-01-01

    This volume is the first of two volumes containing the revised and completed notes lectures given at the school "Quantum Independent Increment Processes: Structure and Applications to Physics". This school was held at the Alfried-Krupp-Wissenschaftskolleg in Greifswald during the period March 9 – 22, 2003, and supported by the Volkswagen Foundation. The school gave an introduction to current research on quantum independent increment processes aimed at graduate students and non-specialists working in classical and quantum probability, operator algebras, and mathematical physics. The present first volume contains the following lectures: "Lévy Processes in Euclidean Spaces and Groups" by David Applebaum, "Locally Compact Quantum Groups" by Johan Kustermans, "Quantum Stochastic Analysis" by J. Martin Lindsay, and "Dilations, Cocycles and Product Systems" by B.V. Rajarama Bhat.

  9. Field Independent Cosmic Evolution

    Directory of Open Access Journals (Sweden)

    Nayem Sk

    2013-01-01

    Full Text Available It has been shown earlier that Noether symmetry does not admit a form of corresponding to an action in which is coupled to scalar-tensor theory of gravity or even for pure theory of gravity taking anisotropic model into account. Here, we prove that theory of gravity does not admit Noether symmetry even if it is coupled to tachyonic field and considering a gauge in addition. To handle such a theory, a general conserved current has been constructed under a condition which decouples higher-order curvature part from the field part. This condition, in principle, solves for the scale-factor independently. Thus, cosmological evolution remains independent of the form of the chosen field, whether it is a scalar or a tachyon.

  10. TO BE INDEPENDENT

    Institute of Scientific and Technical Information of China (English)

    石波

    2000-01-01

    @@ Ⅰ. Introduction At present, in the college, English extensive reading class, most students are not used to being independent. They always ask the teacher to explain the passages sentence by sentence and they need a lot of time to use the dictionary. Yet, we should take the responsibility for the students by making clear the difference between intensive and extensive reading. The traditional teaching approaches pays more attention to the teacher-centered way;the teacher always plays a monodrama, and the teacher dominates the class. The students are lack initiative. Some students do not know where they could start from, and the others are short of fast-reading skills, always fixing their eyes on one word or one sentence. Under the new situation and new thinking, students should learn to be more independent.

  11. Effect of crystallographic orientation on hillock formation in thermally cycled large grain tin films

    Science.gov (United States)

    Koppes, John Patrick

    Tin whiskers and hillocks grow spontaneously from the surfaces of polycrystalline Sn films at room temperature. Whiskers can grow long enough to cause short circuits in electronic devices. We hypothesized that the anisotropies of the crystal structure lead to locally high strain energies that are relieved by the growth of whiskers and hillocks. This research studies hillock formations on large grain Sn-alloy films relative to the crystallographic orientations of the adjacent grains. Large grain films were produced by solidifying 96.5wt% Sn - 3wt% Ag - 0.5wt% Cu solder alloy on a Cu substrate. These surface defects (hillocks) grew predominately at grain boundaries during thermal cycling. The formation of the surface defects between two grains created a pseudo-bi-crystal sample geometry, making it ideal for studying surface defects relative to the local crystallographic orientations and the grains' corresponding anisotropic properties. The crystallographic orientations of the grains were studied with Electron Backscatter Diffraction (EBSD) and Laue micro-diffraction at the Lawrence Berkeley National Laboratory Advanced Light Source. Local orientation studies of the surface defects and the surrounding grains indicated that the surface defects nucleated and grew with low dislocation densities. In addition, the linear surface defect densities along the grain boundaries were measured and observed to change as a function of orientation. The change in linear defect density with respect to orientation was due, in part, to the anisotropy of the coefficient of thermal expansion of β-Sn. In addition, it was important to account for elastic anisotropies. The elastic stresses, strains, and strain energy densities of the microstructures were determined with Object Oriented Finite element analysis. The simulations indicated that during thermal cycling the local stresses exceeded the yield strength. As a result, the highest linear defect densities did not occur at orientations

  12. The peculiarities of the crystallographics modification of a tissues from corpse during putrefactive corpse transformation

    Directory of Open Access Journals (Sweden)

    Fedorova Е.А.

    2013-12-01

    Full Text Available Background. The crystallographic method was used to study the extracts of organs and blood in forensic medicine is not developed yet. However, it is fairly easy to use and does not require additional special equipment, so there is quite promising. Objective. The aim of research are became basis of possibility and effectively to use by thezygraphy method for medico-legal definition of prescription of approach of death by tissue of a corpse during its putrefaction. Methods. Thezygraphy method is used a modification of crystallogramms during dynamics postmortem period for medico-legal definition of prescription of approach of death. Sectional material consisted of the corpses of people who died from violent and nonviolent death in the age range from 18 to 92 years. All the bodies after death were preserved in the same temperature conditions. The tissues from various internal organs: brain, heart, lungs, kidneys, liver, spleen and blood from 30 cadavers were the object of sectional study. There for 939 biological objects were investigated. Results. The article deals with generalization the crystallography (thezigraphy observation of crystallogramms from different tissues extract and blood depending on the different cause of violent and nonviolent death. The main purpose is to identify common crystallogramms features of the extracts of internal organs taken during putrefactive corpse transformation of people who died from various kinds of death. It has been proved that: 1.The typical сrystallogramms were formed from various tissue extracts: blood, brain, heart, lungs, liver, kidneys, spleen in first day after of approach of death, depending on the cause of deaths. 2. In the dynamics of postmortem period and putrefactive transformation of the corpses (first week the dynamic changes occur in crystallographic patterns obtained from extracts of the internal organs, and they can be used to establish the approach of death. Conclusion. The thezygraphy

  13. Bayesian Independent Component Analysis

    DEFF Research Database (Denmark)

    Winther, Ole; Petersen, Kaare Brandt

    2007-01-01

    In this paper we present an empirical Bayesian framework for independent component analysis. The framework provides estimates of the sources, the mixing matrix and the noise parameters, and is flexible with respect to choice of source prior and the number of sources and sensors. Inside the engine...... in a Matlab toolbox, is demonstrated for non-negative decompositions and compared with non-negative matrix factorization....

  14. Random Independence Systems

    Science.gov (United States)

    1981-11-01

    Whitney provided a set of axioms for a structure commonly called i a matroid. Matroid theory (see ( Tutte , 19711, [Lawler, 19761) has applications to a wide...applicable in this case. On the other hand, there is no known efficient ( polynomial time) algorithm for constructing cliques of size 2 log n with...intersection. The problem of constructing a maximal independent set in the intersection of k matroids has a polynomial time (in tEl) algorithm [Lawler, 197

  15. Crystal structure of bis-(3-bromo-mesit-yl)(quino-lin-1-ium-8-yl)boron(III) tribromide.

    Science.gov (United States)

    Son, Jungho; Tamang, Sem Raj; Hoefelmeyer, James D

    2015-09-01

    The title compound, C27H26.82BBr2.18N(+)·Br3 (-), is a cationic tri-aryl-borane isolated as its tribromide salt. The aryl substituents include a protonated 8-quinolyl group and two 3-bromo-mesityl groups. The mol-ecule was prepared on combination of 3:1 Br2 and dimesit-yl(quinolin-8-yl)borane in hexa-nes. The refinement of the structure indicated a degree of 'over-bromination' (beyond two bromine atoms) for the cation. There are two tribromide ions in the asymmetric unit, both completed by crystallographic inversion symmetry.

  16. Diaqua-bis(2-pyridylphospho-nato N-oxide-κO,O)cobalt(II).

    Science.gov (United States)

    Ma, Yun-Sheng; Lu, Tian-Xian

    2008-11-13

    In the title complex, [Co(C(5)H(5)NO(4)P)(2)(H(2)O)(2)], the Co(II) ion, which lies on a crystallographic inversion center, is coordin-ated by four O atoms from two bidentate 2-phospho-nato-pyridine N-oxide ligands and two O atoms from two water ligands in a slightly distorted octa-hedral environment. Mol-ecules are inter-linked by three O-H⋯O hydrogen bonds and one weak C-H⋯O inter-action, forming a three-dimensional supra-molecular structure.

  17. Purification, identification and preliminary crystallographic studies of Pru du amandin, an allergenic protein from Prunus dulcis

    Energy Technology Data Exchange (ETDEWEB)

    Gaur, Vineet; Sethi, Dhruv K.; Salunke, Dinakar M., E-mail: dinakar@nii.res.in [National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067 (India)

    2008-01-01

    The purification, identification, crystallization and preliminary crystallographic studies of an allergy-related protein, Pru du amandin, from P. dulcis nuts are reported. Food allergies appear to be one of the foremost causes of hypersensitivity reactions. Nut allergies account for most food allergies and are often permanent. The 360 kDa hexameric protein Pru du amandin, a known allergen, was purified from almonds (Prunus dulcis) by ammonium sulfate fractionation and ion-exchange chromatography. The protein was identified by a BLAST homology search against the nonredundant sequence database. Pru du amandin belongs to the 11S legumin family of seed storage proteins characterized by the presence of a cupin motif. Crystals were obtained by the hanging-drop vapour-diffusion method. The crystals belong to space group P4{sub 1} (or P4{sub 3}), with unit-cell parameters a = b = 150.7, c = 164.9 Å.

  18. Paramagnetic and crystallographic effects of low temperature ashing on human bone and tooth enamel.

    Science.gov (United States)

    Tochon-Danguy, H J; Very, J M; Geoffroy, M; Baud, C A

    1978-02-28

    Low temperature ashing by excited gas (LTA) causes crystallographic and paramagnetic alterations of the human bone and tooth enamel mineral. On the one hand, LTA induces variations of the alpha lattice parameter. These variations depend upon the nature of the gas used, but are little affected by its degree of excitation. Trapping of gas molecules in the crystal structure is demonstrated. On the other hand, LTA produces two preponderant paramagnetic centers in bone and enamel samples at 20 degrees C. Their inorganic origin clearly indicated. One of the two radicals has been identified as O3- (g1 = 2.002, g2 = 2.010, g3 = 2.016) and the other as (CO3-3 (parallel = 1.996, g = perpendicular 2.003). Variations of the alpha lattice parameter and trapping of paramagnetic gas species do not seem to be directly related.

  19. Radiation of high-energy electrons near crystallographic axes and planes of a diamond crystal

    Energy Technology Data Exchange (ETDEWEB)

    Avakyan, R.O.; Avakyan, E.O.; Avetisyan, A.E.

    1986-05-01

    The paper is devoted to the experimental study of high-energy electrons interaction with diamond crystals of different thicknesses at small incident angles with respect to crystallographic axes and planes. The effect of the so-called channeling phenomenon on the process of electron radiation in a crystal is studied. Results of the measurements of 4.5. GeV electrons radiation spectra at incident angles approximately O are given. For comparison, we have also presented the spectrum of the radiation on an amorphous target /sup 12/C of similar thickness. Results indicate that the low-energy part of spectra greatly surpass the amorphous spectrum with a pronounced peak structure, with peak widths being noticeably wider in the case of axial channeling than in the planar case. Spectra are measured by a No.I(Tl) total absorption detector. The experiment is performed on the Yerevan electron synchrotron beam with small angular divergence.

  20. Platinum Group Thiophenoxyimine Complexes: Syntheses,Crystallographic and Computational Studies of Structural Properties

    Energy Technology Data Exchange (ETDEWEB)

    Krinsky, Jamin L.; Arnold, John; Bergman, Robert G.

    2006-10-03

    Monomeric thiosalicylaldiminate complexes of rhodium(I) and iridium(I) were prepared by ligand transfer from the homoleptic zinc(II) species. In the presence of strongly donating ligands, the iridium complexes undergo insertion of the metal into the imine carbon-hydrogen bond. Thiophenoxyketimines were prepared by non-templated reaction of o-mercaptoacetophenone with anilines, and were complexed with rhodium(I), iridium(I), nickel(II) and platinum(II). X-ray crystallographic studies showed that while the thiosalicylaldiminate complexes display planar ligand conformations, those of the thiophenoxyketiminates are strongly distorted. Results of a computational study were consistent with a steric-strain interpretation of the difference in preferred ligand geometries.

  1. Processing and crystallographic structure of non-equilibrium Si-doped HfO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Dong; Fancher, Chris M.; Esteves, Giovanni; Jones, Jacob L., E-mail: jacobjones@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Zhao, Lili [School of Information Science and Technology, Northwest University, Xi' an 710127 (China)

    2015-06-28

    Si-doped HfO{sub 2} was confirmed to exist as a non-equilibrium state. The crystallographic structures of Si-doped HfO{sub 2} were studied using high-resolution synchrotron X-ray diffraction and the Rietveld refinement method. Incorporation of Si into HfO{sub 2} and diffusion of Si out of (Hf,Si)O{sub 2} were determined as a function of calcination temperature. Higher thermal energy input at elevated calcination temperatures resulted in the formation of HfSiO{sub 4}, which is the expected major secondary phase in Si-doped HfO{sub 2}. The effect of SiO{sub 2} particle size (nano- and micron-sized) on the formation of Si-doped HfO{sub 2} was also determined. Nano-crystalline SiO{sub 2} was found to incorporate into HfO{sub 2} more readily.

  2. Quantification of thin film crystallographic orientation using X-ray diffraction with an area detector.

    Science.gov (United States)

    Baker, Jessy L; Jimison, Leslie H; Mannsfeld, Stefan; Volkman, Steven; Yin, Shong; Subramanian, Vivek; Salleo, Alberto; Alivisatos, A Paul; Toney, Michael F

    2010-06-01

    As thin films become increasingly popular (for solar cells, LEDs, microelectronics, batteries), quantitative morphological and crystallographic information is needed to predict and optimize the film's electrical, optical, and mechanical properties. This quantification can be obtained quickly and easily with X-ray diffraction using an area detector in two sample geometries. In this paper, we describe a methodology for constructing complete pole figures for thin films with fiber texture (isotropic in-plane orientation). We demonstrate this technique on semicrystalline polymer films, self-assembled nanoparticle semiconductor films, and randomly packed metallic nanoparticle films. This method can be immediately implemented to help understand the relationship between film processing and microstructure, enabling the development of better and less expensive electronic and optoelectronic devices.

  3. Maximum a posteriori estimation of crystallographic phases in X-ray diffraction tomography

    Energy Technology Data Exchange (ETDEWEB)

    Gürsoy, Doǧa; Bicer, Tekin; Almer, Jonathan D.; Kettimuthu, Rajkumar; Stock, Stuart; De Carlo, Francesco

    2015-06-13

    A maximum a posteriori approach is proposed for X-ray diffraction tomography for reconstructing three-dimensional spatial distribution of crystallographic phases and orientations of polycrystalline materials. The approach maximizes the a posteriori density which includes a Poisson log-likelihood and an a priori term that reinforces expected solution properties such as smoothness or local continuity. The reconstruction method is validated with experimental data acquired from a section of the spinous process of a porcine vertebra collected at the 1-ID-C beamline of the Advanced Photon Source, at Argonne National Laboratory. The reconstruction results show significant improvement in the reduction of aliasing and streaking artefacts, and improved robustness to noise and undersampling compared to conventional analytical inversion approaches. The approach has the potential to reduce data acquisition times, and significantly improve beamtime efficiency.

  4. Ge/SrTiO{sub 3}(001): Correlation between interface chemistry and crystallographic orientation

    Energy Technology Data Exchange (ETDEWEB)

    Gobaut, B.; Penuelas, J.; Grenet, G.; Ferrah, D.; Benamrouche, A.; Chettaoui, A.; Robach, Y.; Botella, C.; Saint-Girons, G. [Universite de Lyon, Institut des Nanotechnologies de Lyon, Ecole Centrale de Lyon, 36 avenue Guy de Collongue, 69134 Ecully (France); El Kazzi, M.; Silly, M. G.; Sirotti, F. [Synchrotron SOLEIL (TEMPO beamline), l' Orme des Merisiers, Saint-Aubin, 91192 Gif-sur-Yvette (France)

    2012-11-01

    In this work, the desorption of a submonolayer deposit of Ge on SrTiO{sub 3}(001) is studied by reflection high energy electron diffraction. The results are compared to those of a previous experiment done using soft x-ray photoelectron spectroscopy. Combining these techniques allows for correlating interface chemistry and crystal orientation, and for bringing clarifying elements concerning the competition between (111) and (001) crystal orientation typical for the semiconductor/perovskite epitaxial systems. Despite poor interface matching, (111)-oriented islands are stabilized at the expense of (001)-oriented islands due to the relatively low energy of their free facets. Such 'surface energy driven' crystallographic orientation of the deposit is enhanced by the low adhesion energy characteristic of the Ge/SrTiO{sub 3} system.

  5. Dianthraceno[a,e]pentalenes: Synthesis, crystallographic structures and applications in organic field-effect transistors

    KAUST Repository

    Dai, Gaole

    2015-01-01

    Two soluble and stable dianthraceno[a,e]pentalenes with two (DAP1) and six (DAP2) phenyl substituents were synthesized. Both compounds possess a small energy band gap and show amphoteric redox behaviour due to intramolecular donor-accepter interactions. X-ray crystallographic analysis revealed that DAP2 has a closely packed structure with multi-dimensional [C-H⋯π] interactions although there are no π-π interactions between the dianthraceno[a,e]pentalene cores. As a result, solution-processed field effect transistors based on DAP2 exhibited an average hole mobility of 0.65 cm2 V-1 s-1. Under similar conditions, DAP1 showed an average field effect hole mobility of 0.001 cm2 V-1 s-1. This journal is

  6. Preliminary crystallographic data for the thiamin diphosphate-dependent enzyme pyruvate decarboxylase from brewers' yeast.

    Science.gov (United States)

    Dyda, F; Furey, W; Swaminathan, S; Sax, M; Farrenkopf, B; Jordan, F

    1990-10-15

    Single crystals of the thiamin diphosphate (the vitamin B1 coenzyme)-dependent enzyme pyruvate decarboxylase (EC 4.1.1.1) from brewers' yeast have been grown using polyethylene glycol as a precipitating agent. Crystals of the homotetrameric version alpha 4 of the holoenzyme are triclinic, space group P1, with cell constants a = 81.0, b = 82.4, c = 116.6 A, alpha = 69.5 beta = 72.6, gamma = 62.4 degrees. The crystals are reasonably stable in a rotating anode x-ray beam and diffract to at least 2.5 A resolution. The Vm value of 2.55 A/dalton is consistent with a unit cell containing four subunits with mass of approximately 60 kDa each. Rotation function results with native data indicate strong non-crystallographic 222 symmetry relating the four identical subunits, thus density averaging methods are likely to play a role in the structure determination.

  7. Crystallographic analysis of CVD films using x-ray polychromatic radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lavelle, B. [CNRS, Toulouse (France). Centre d`Elaboration de Materiaux et d`Etudes Structurales; Brissonneau, L.; Baggot, E.; Vahlas, C. [INPT-CNRS, Toulouse (France). Lab. Materiaux et Interfaces

    1998-12-31

    The Energy Dispersive X-ray Diffractometry (EDXD) technique was tested for in-situ crystallographic characterization of nickel films processed by chemical vapor deposition (CVD). The diffracted beam at low Bragg angle was analyzed in energy by a solid state detector. A nickel reference sample was used to face the problems of EDXD background signal and uncertainty of sample location. The relative accuracy on lattice parameters measurements is 1.5.10{sup {minus}3}, to be compared to 0.5.10{sup {minus}3} for classical (monochromatic) X-ray diffraction. Texture measurements yields results in agreement with those obtained form recent texture goniometer. Finally, an estimation of the thickness was obtained from the intensity of nickel fluorescence peak. In view of the obtained results, EDXD appears to be a promising technique for in-situ studies. Although less powerful compared to the synchrotron facility, it is more flexible and can be applied at lower cost.

  8. Crystallographic and magnetic structures of Pr6Fe13Ge studied by powder neutron diffraction

    Institute of Scientific and Technical Information of China (English)

    Wang Fang-Wei; Zhang Pan-Lin; Shen Bao-Gen; Yan Qi-Wei

    2004-01-01

    Crystallographic and magnetic structures of Pr6Fel3Ge have been investigated by high-resolution powder neutron diffraction in the temperature range of 10-300 K. The magnetic structure consists of ferromagnetic Pr6Fe13 slabs that alternate antiferromagnetically, along c, with the next Pr6Fe13 slab separated by a non-magnetic Ge layer. The magnetic moments lie within the ab-planes. The propagation vector of this structure is k=(001) with respect to the conventional reciprocal lattice of the Ⅰ-centred structure. However, the temperature-dependence of neutron-scattering intensity of the (110) Bragg peak, very similar to the temperature-dependent magnetization measured by SQUID magnetometer,indicates that a small c-axis ferromagnetic component should be added to the above antiferromagnetic model.

  9. Lytic polysaccharide monooxygenases: a crystallographer's view on a new class of biomass-degrading enzymes

    Directory of Open Access Journals (Sweden)

    Kristian E. H. Frandsen

    2016-11-01

    Full Text Available Lytic polysaccharide monooxygenases (LPMOs are a new class of microbial copper enzymes involved in the degradation of recalcitrant polysaccharides. They have only been discovered and characterized in the last 5–10 years and have stimulated strong interest both in biotechnology and in bioinorganic chemistry. In biotechnology, the hope is that these enzymes will finally help to make enzymatic biomass conversion, especially of lignocellulosic plant waste, economically attractive. Here, the role of LPMOs is likely to be in attacking bonds that are not accessible to other enzymes. LPMOs have attracted enormous interest since their discovery. The emphasis in this review is on the past and present contribution of crystallographic studies as a guide to functional understanding, with a final look towards the future.

  10. Preparation, crystallization and preliminary crystallographic analysis of old yellow enzyme from Trypanosoma cruzi

    Energy Technology Data Exchange (ETDEWEB)

    Sugiyama, Shigeru [Maruwa Foods Co. Ltd, Tsutsui-cho 170-1, Yamatokoriyama, Nara 639-1123 (Japan); Tokuoka, Keiji [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Uchiyama, Nahoko [Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874 (Japan); Okamoto, Naoki; Okano, Yousuke; Matsumura, Hiroyoshi [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Inaka, Koji [Maruwa Foods Co. Ltd, Tsutsui-cho 170-1, Yamatokoriyama, Nara 639-1123 (Japan); Urade, Yoshihiro [Department of Molecular Behavioral Biology, Osaka Bioscience Institute, Osaka 565-0874 (Japan); Inoue, Tsuyoshi, E-mail: inouet@chem.eng.osaka-u.ac.jp [Department of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamada-Oka, Suita, Osaka 565-0871 (Japan); Maruwa Foods Co. Ltd, Tsutsui-cho 170-1, Yamatokoriyama, Nara 639-1123 (Japan)

    2007-10-01

    Old yellow enzyme from Trypanosoma cruzi, has been crystallized using the hanging-drop vapour-diffusion method. Old yellow enzyme (OYE) is an NADPH oxidoreductase that contains a flavin mononucleotide as a prosthetic group. The OYE from Trypanosoma cruzi, which produces prostaglandin F{sub 2α}, a potent mediator of various physiological and pathological processes, from prostaglandin H2. The protein was recombinantly expressed and purified from Escherichia coli and was crystallized using the hanging-drop vapour-diffusion method. The crystal belongs to the monoclinic space group P2{sub 1}, with unit-cell parameters a = 56.3, b = 78.8, c = 78.8 Å, β = 93.4° and two molecules per asymmetric unit. The crystals were suitable for X-ray crystallographic studies and diffracted to 1.70 Å resolution. A Patterson search method is in progress using the structure of OYE from Pseudomonas putida as a starting model.

  11. Transfer of olivine crystallographic orientation through a cycle of serpentinisation and dehydration

    Science.gov (United States)

    Dunkel, Kristina G.; Austrheim, Håkon; Ildefonse, Benoit; Jamtveit, Bjørn

    2017-08-01

    Our ability to decipher the mechanisms behind metamorphic transformation processes depends in a major way on the extent to which crystallographic and microstructural information is transferred from one stage to another. Within the Leka Ophiolite Complex in the Central Norwegian Caledonides, prograde olivine veins that formed by dehydration of serpentinite veins in dunites exhibit a characteristic distribution of microstructures: The outer part of the veins comprises coarse-grained olivine that forms an unusual, brick-like microstructure. The inner part of the veins, surrounding a central fault, is composed of fine-grained olivine. Where the fault movement included a dilational component, optically clear, equant olivine occurs in the centre. Electron backscatter diffraction mapping reveals that the vein olivine has inherited its crystallographic preferred orientation (CPO) from the olivine in the porphyroclastic host rock; however, misorientation is weaker and associated to different rotation axes. We propose that prograde olivine grew epitaxially on relics of mantle olivine and thereby acquired its CPO. Growth towards pre-existing microfractures along which serpentinisation had occurred led to straight grain boundaries and a brick-like microstructure in the veins. When dehydration embrittlement induced slip, a strong strain localisation on discrete fault planes prevented distortion of the CPO due to cataclastic deformation; grain size reduction did not significantly modify the olivine CPO. This illustrates how a CPO can be preserved though an entire metamorphic cycle, including hydration, dehydration, and deformation processes, and that the CPO and the microstructures (e.g. grain shape) of one phase do not necessarily record the same event.

  12. Crystallization and preliminary crystallographic analysis of l-asparaginase from Erwinia carotovora

    Energy Technology Data Exchange (ETDEWEB)

    Wikman, Linnea E. K. [Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20521 (Finland); Krasotkina, Julya; Kuchumova, Anastasia; Sokolov, Nikolay N. [Institute for Biomedical Chemistry, Russian Academy of Medical Sciences, 559-B, 10 Pogodinskay St, Moscow 119121 (Russian Federation); Papageorgiou, Anastassios C., E-mail: tassos.papageorgiou@btk.fi [Turku Centre for Biotechnology, University of Turku and Åbo Akademi University, Turku 20521 (Finland)

    2005-04-01

    Er. carotovoral-asparaginase, a potential antileukaemic agent, has been crystallized. Crystals diffract to 2.6 Å using a rotating-anode source and belong to space group P2{sub 1}, with unit-cell parameters a = 78.0, b = 112.3, c = 78.7 Å, β = 101.9° and a homotetramer in the crystallographic asymmetric unit. Bacterial l-asparaginases have been used as therapeutic agents in the treatment of acute childhood lymphoblastic leukaemia for over 30 y. However, their use is limited owing to the glutaminase activity of the administered enzymes, which results in serious side effects. In contrast, l-asparaginase from Erwinia carotovora exhibits low glutaminase activity at physiological concentrations of l-asparagine and l-glutamine in the blood. Recombinant Er. carotovoral-asparaginase was crystallized in the presence of l-glutamate by the hanging-drop vapour-diffusion method using 10 mg ml{sup −1} purified enzyme, 16–18%(w/v) PEG 3350 and 0.2 M NaF. X-ray diffraction data were collected to 2.6 Å at 293 K using an in-house rotating-anode generator. The crystals belong to the monoclinic P2{sub 1} space group, with unit-cell parameters a = 78.0, b = 112.3, c = 78.7 Å, β = 101.9° and a homotetramer in the crystallographic asymmetric unit. A molecular-replacement solution has been found and refinement is currently in progress. The crystal structure may provide leads towards protein-engineering efforts aimed at safer asparaginase administration in leukaemia treatment.

  13. Independence among People with Disabilities: II. Personal Independence Profile.

    Science.gov (United States)

    Nosek, Margaret A.; And Others

    1992-01-01

    Developed Personal Independence Profile (PIP) as an instrument to measure aspects of independence beyond physical and cognitive functioning in people with diverse disabilities. PIP was tested for reliability and validity with 185 subjects from 10 independent living centers. Findings suggest that the Personal Independence Profile measures the…

  14. Crystal structures of (±)-(1SR,5SR,6SR,7SR,10SR,11SR,13RS,14SR)-13-hy-droxy-7-meth-oxy-meth-oxy-11,15,18,18-tetra-methyl-3-oxo-2,4-dioxa-tetra-cyclo-[12.3.1.0(1,5).0(6,11)]octa-dec-15-en-10-yl benzoate, its 13-epimer and 13-one derivative.

    Science.gov (United States)

    Oishi, Takeshi; Fukaya, Keisuke; Yamaguchi, Yu; Sugai, Tomoya; Watanabe, Ami; Sato, Takaaki; Chida, Noritaka

    2015-05-01

    The title compounds, C29H38O8·0.25C5H12, (A), C29H38O8, (B), and C29H36O8, (C), are tetra-cyclic benzoates possessing a taxane skeleton with a fused dioxolane ring as the core structure. In the asymmetric unit of (A), there are two independent benzoate mol-ecules (A and A') and a half mol-ecule of solvent pentane disordered about an inversion center. The mol-ecular conformations of (A), (B) and (C) are similar except for the flexible meth-oxy-meth-oxy group. The cyclo-hexane, cyclo-hexene and central cyclo-octane rings adopt chair, half-chair and chair-chair (extended crown) forms, respectively. The dioxolane rings are essentially planar, while the dioxolane ring of A' is slightly twisted from the mean plane. In the crystal of (A), inter-molecular O-H⋯O, C-H⋯O and C-H⋯π inter-actions link the independent benzoates alternately, forming a chain structure. In the crystals of (B) and (C), mol-ecules are linked through O-H⋯O and C-H⋯π inter-actions, and C-H⋯O hydrogen bonds, respectively, into similar chains. Further, weak inter-molecular C-H⋯O inter-actions connect the chains into a three-dimensional network in (A) and a sheet in (B), whereas no other interactions are observed for (C).

  15. Synthetic, crystallographic, computational, and biological studies of 1,4-difluorobenzo[c]phenanthrene and its metabolites.

    Science.gov (United States)

    Bae, Suyeal; Mah, Heduck; Chaturvedi, Surendrakumar; Jeknic, Tamara Musafia; Baird, William M; Katz, Amy K; Carrell, H L; Glusker, Jenny P; Okazaki, Takao; Laali, Kenneth K; Zajc, Barbara; Lakshman, Mahesh K

    2007-09-28

    1,4-Difluorobenzo[c]phenanthrene (1,4-DFBcPh) and its putative metabolites, the dihydrodiol and diol epoxides, have been synthesized and structurally characterized, and the extent of DNA binding by the metabolites has been assessed. 1,4-DFBcPh and 1,4-difluoro-10-methoxybenzo[c]phenanthrene were prepared by photochemical cyclization of appropriate naphthylphenylethylenes. The dihydrodiol was synthesized from 1,4-difluoro-10-methoxybenzo[c]phenanthrene, and the diol epoxides were diastereoselectively synthesized from the dihydrodiol. Interesting differences were noted in 1H NMR spectra of the series 1 (syn) diol epoxides of benzo[c]phenanthrene (BcPh) and 1,4-DFBcPh; the BcPh diol epoxide displays a quasi-diequatorial orientation of the hydroxyl groups, but in the 1,4-DFBcPh case these are diaxially disposed. This difference probably stems from the presence of the fjord-region fluorine atom in 1,4-DFBcPh. A through-space, fjord-region H-F coupling has also been observed for 1,4-DFBcPh and its derivatives. Comparative X-ray crystallographic analyses of BcPh and 1,4-DFBcPh and their dihydrodiols show that introduction of fluorine increases the molecular distortion by about 6-7 degrees . As a guide to estimating the molecular distortion and its effects, and for comparison with the X-ray structures in known cases, optimized structures of BcPh, 1,4-DFBcPh, and 1,4-DMBcPh (the dimethyl analogue) as well as their dihydrodiols and diol epoxides were computed. Relative aromaticities of these compounds were assessed by nucleus-independent chemical shift calculations, and 13C NMR chemical shifts were computed by gauge-inducing atomic orbital calculations. 1,4-DFBcPh and its dihydrodiol were subjected to metabolism, and the amount of DNA binding in human breast cancer MCF-7 cells was assessed. The extent of DNA binding was then compared with that for BcPh and its dihydrodiol and the potent carcinogen benzo[a]pyrene. The 1,4-DFBcPh series 2 (anti) diol epoxide-derived DNA

  16. The effect of crystallographic texture on stress-induced martensitic transformation in NiTi: A computational analysis.

    Science.gov (United States)

    Weafer, F M; Guo, Y; Bruzzi, M S

    2016-01-01

    NiTi׳s superelasticity is exploited in a number of biomedical devices, in particular self-expanding endovascular stents. These stents are often laser-cut from textured micro-tubing; texture is the distribution of crystallographic grain orientations in a polycrystalline material which has been experimentally shown to have a marked influence on mechanical properties. This study offers a computational examination into the effect of texture on the stress-induced martensite transformation (SIMT) in a micro-dogbone NiTi specimen subject to tensile loading. Finite Element Analysis (FEA) is employed to simulate the transformational behaviour of the specimen on a micro-scale level. To represent a realistic grain structure in the FEA model, grains present in a 200µm×290µm test site located at the centre edge of the specimen were identified using Scanning Electron Microscopy (SEM). Grains are assumed to have homogenous behaviour with properties varying according to their crystallographic orientation to the loading direction. Required material properties were extracted from uniaxial stress-strain curves of single crystals for each crystallographic orientation for input into the in-built UMAT/Nitinol. The orientation of each grain in the test site was identified using Electron Back-Scatter Diffraction (EBSD) techniques. In this way, a quantitative explanation is offered to the effect of crystallographic texture on SIMT. Finally, the evolution of grains in the specimen, during the transformation process, was experimentally investigated by means of an in-situ SEM tensile test.

  17. Crystallographic Behavior of Iron Oxide Minerals in the Deformed Iron Formation of Quadrilátero Ferrífero

    Science.gov (United States)

    Duarte Lisboa, Filipe Augusto; Lagoeiro, Leonardo; Martins Graça, Leonardo; Ávila, Carlos Fernando; Ferreira Barbosa, Paola

    2016-04-01

    The Quadrilátero Ferrífero (QF) which is located in Brazil represents a mineral province of great importance for hosting Banded Iron Formation deposits (BIFs). The Alegria mine which belongs to Vale Company is located in the east part of Quadrilátero Ferrífero and it explores iron ore from a region of great structural complexity. A deformed BIF sample that presents a micro-fold on quartz and hematite bands was analyzed through Electron Backscatter Diffraction technique (EBSD) in order to relate the crystallographic orientations with the microstructures along the micro-fold envelop. For the sample orientation the Z-axis is taken parallel to the fold limb, Y-axis is perpendicular to the fold hinge and X-axis perpendicular to the YZ plane. In the limbs hematite grains are mostly stretched whereas at the hinge grains tend to be somewhat equant. On the other hand, quartz grain shapes are invariable along the fold, with a few exceptions in the hinge where grains are slightly elongated. Grains of hematite present a strong c-axis ({0001}) preferred orientation forming a subtle girdle somewhat parallel to the XY plane of the strain ellipsoid determined macroscopically (XY being the foliation plane), and a strong () crystallographic fabric approximately parallel to the Z-axis. Similarly, the poles to the prismatic planes ({m} or {10bar10}) also have a stronger crystallographic fabric parallel to the Z axis. It seems that there are two crossing planes for the orientation of and {m} with the two maxima at the intersection of the two planes. Typical hematite crystallographic fabrics are somewhat distinct, since {c} axis commonly forms a very strong fiber texture parallel to the pole of the foliation. Most studies regard such crystallographic texture as evidence for high activity of {c} slip. The {c} girdles observed here are common for mica grains under rigid body rotation in constriction strain, which mechanism is commonly observed in the hematite grains of the sample. The

  18. The importance of board independence

    NARCIS (Netherlands)

    Zijl, N.J.M.

    2012-01-01

    Although the attributed importance of board independence is high, a clear definition of independence does not exist. Furthermore, the aim and consequences of independence are the subject of discussion and empirical evidence about the impact of independence is weak and disputable. Despite this lack o

  19. Frame independent cosmological perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Prokopec, Tomislav; Weenink, Jan, E-mail: t.prokopec@uu.nl, E-mail: j.g.weenink@uu.nl [Institute for Theoretical Physics and Spinoza Institute, Utrecht University, Leuvenlaan 4, 3585 CE Utrecht (Netherlands)

    2013-09-01

    We compute the third order gauge invariant action for scalar-graviton interactions in the Jordan frame. We demonstrate that the gauge invariant action for scalar and tensor perturbations on one physical hypersurface only differs from that on another physical hypersurface via terms proportional to the equation of motion and boundary terms, such that the evolution of non-Gaussianity may be called unique. Moreover, we demonstrate that the gauge invariant curvature perturbation and graviton on uniform field hypersurfaces in the Jordan frame are equal to their counterparts in the Einstein frame. These frame independent perturbations are therefore particularly useful in relating results in different frames at the perturbative level. On the other hand, the field perturbation and graviton on uniform curvature hypersurfaces in the Jordan and Einstein frame are non-linearly related, as are their corresponding actions and n-point functions.

  20. Emissivity independent optical pyrometer

    Science.gov (United States)

    Earl, Dennis Duncan; Kisner, Roger A.

    2017-04-04

    Disclosed herein are representative embodiments of methods, apparatus, and systems for determining the temperature of an object using an optical pyrometer. Certain embodiments of the disclosed technology allow for making optical temperature measurements that are independent of the surface emissivity of the object being sensed. In one of the exemplary embodiments disclosed herein, a plurality of spectral radiance measurements at a plurality of wavelengths is received from a surface of an object being measured. The plurality of the spectral radiance measurements is fit to a scaled version of a black body curve, the fitting comprising determining a temperature of the scaled version of the black body curve. The temperature is then output. The present disclosure is not to be construed as limiting and is instead directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone or in various combinations and subcombinations with one another.

  1. Emissivity independent optical pyrometer

    Energy Technology Data Exchange (ETDEWEB)

    Earl, Dennis Duncan; Kisner, Roger A.

    2017-04-04

    Disclosed herein are representative embodiments of methods, apparatus, and systems for determining the temperature of an object using an optical pyrometer. Certain embodiments of the disclosed technology allow for making optical temperature measurements that are independent of the surface emissivity of the object being sensed. In one of the exemplary embodiments disclosed herein, a plurality of spectral radiance measurements at a plurality of wavelengths is received from a surface of an object being measured. The plurality of the spectral radiance measurements is fit to a scaled version of a black body curve, the fitting comprising determining a temperature of the scaled version of the black body curve. The temperature is then output. The present disclosure is not to be construed as limiting and is instead directed toward all novel and nonobvious features and aspects of the various disclosed embodiments, alone or in various combinations and subcombinations with one another.

  2. Comparison of the crystal structures of methyl 4-bromo-2-(meth-oxy-meth-oxy)benzoate and 4-bromo-3-(meth-oxy-meth-oxy)benzoic acid.

    Science.gov (United States)

    Suchetan, P A; Suneetha, V; Naveen, S; Lokanath, N K; Krishna Murthy, P

    2016-04-01

    The title compounds, C10H11BrO4, (I), and C9H9BrO4, (II), are derivatives of bromo-hy-droxy-benzoic acids. Compound (II) crystallizes with two independent mol-ecules (A and B) in the asymmetric unit. In both (I) and (II), the O-CH2-O-CH3 side chain is not in its fully extended conformation; the O-C-O-C torsion angle is 67.3 (3) ° in (I), and -65.8 (3) and -74.1 (3)° in mol-ecules A and B, respectively, in compound (II). In the crystal of (I), mol-ecules are linked by C-H⋯O hydrogen bonds, forming C(5) chains along [010]. The chains are linked by short Br⋯O contacts [3.047 (2) Å], forming sheets parallel to the bc plane. The sheets are linked via C-H⋯π inter-actions, forming a three-dimensional architecture. In the crystal of (II), mol-ecules A and B are linked to form R 2 (2)(8) dimers via two strong O-H⋯O hydrogen bonds. These dimers are linked into ⋯A-B⋯A-B⋯A-B⋯ [C 2 (2)(15)] chains along [011] by C-H⋯O hydrogen bonds. The chains are linked by slipped parallel π-π inter-actions [inter-centroid distances = 3.6787 (18) and 3.8431 (17) Å], leading to the formation of slabs parallel to the bc plane.

  3. 5-Acetyl-4-(3-hy-droxy-phen-yl)-6-methyl-1,2,3,4-tetra-hydro-pyrimidin-2-one-tris-(hy-droxy-meth-yl)ammonium chloride (2/1).

    Science.gov (United States)

    Huq, C A M A; Fouzia, S; Nizammohideen, M

    2013-11-13

    The asymmetric unit of the title compound, 2C13H14N2O3·C3H10NO3 (+)·Cl(-), contains two independent mol-ecules (A and B) of the title pyrimidine derivative and one ion-pair of tris-(hy-droxy-meth-yl)ammonium chloride. The pyrimidine ring in each pyrimidine derivative has a half-chair conformation. Its mean plane is inclined to the benzene ring by 87.2 (3)° in mol-ecule A and 85.7 (2)° in mol-ecule B. In the crystal, the pyrimidine derivatives are connected to each other by N-H⋯O hydrogen bonds, forming chains propagating along the b-axis direction. The chains are linked via O-H-Cl hydrogen bonds, forming corrugated sheets lying parallel to the bc plane. The sheets are linked via C-H⋯O hydrogen bonds, forming a three-dimensional framework. The tris-(hy-droxy-meth-yl)ammonium chloride mol-ecules are located in the cages of the framework. There are also further C-H⋯O hydrogen bonds and C-H⋯π inter-actions present in the three-dimensional framework structure. Both the cation and chloride anion of the tris-(hy-droxy-meth-yl)ammonium chloride ion pair are disordered over two positions, with a refined occupancy ratio of 0.418 (8):0.582 (8) for the cation and 0.71 (4):0.29 (4) for the anion.

  4. n-Butyldichlorido{4-cyclo-hexyl-1-[1-(pyridin-2-yl-κN)ethyl-idene]thio-semi-carb-azi-dato-κ²N¹,S}tin(IV).

    Science.gov (United States)

    Affan, Md Abu; Salam, Md Abdus; Asaruddin, Mohd Razip; Ng, Seik Weng; Tiekink, Edward R T

    2012-07-01

    Two independent mol-ecules comprise the asymmetric unit in the title compound, [Sn(C₄H₉)(C₁₄H₁₉N₄S)Cl₂]. In each mol-ecule, the Sn(IV) atom exists within a distorted octa-hedral geometry defined by the N,N',S-tridentate mono-deprotonated Schiff base ligand, two mutually trans Cl atoms, and the α-C atom of the n-butyl group; the latter is trans to the azo-N atom. The greatest distortion from the ideal geometry is found in the nominally trans angle formed by the S and pyridyl-N atoms at Sn [151.72 (7) and 152.04 (7)°, respectively]. In the crystal, mol-ecules are consolidated into a three-dimensional architecture by a combination of N-H⋯Cl, C-H⋯π and π-π inter-actions [inter-centroid distances = 3.6718 (19) and 3.675 (2) Å].

  5. Effect of crystallographic texture and dislocation hardening on limit strain in sheet metal forming

    Science.gov (United States)

    Wen, Xiyu

    2000-10-01

    In the metal industry, sheet metals are widely used to produce packaging materials for consumer goods, for structures such as automobilse, and for building construction and transportation. The desired shape of the products is imparted by plastic deformation in either the cold or hot state. Traditionally, the prediction of the forming limit of sheet metals is based on tensile tests, simulation tests and continuum mathematical models. Continuum models used in the prediction of the plastic behavior of sheet metals are based on average values of mechanical properties such as elongation, yield strength, work hardening and work-hardening rate, which are usually derived from tensile tests. Although attempts have been made to abandon the phenomenological description of the yield function by applying the theory of crystal plasticity to calculate the yield surface of texture polycrystals and hence the limit strains, only the average properties of the microstructure (e.g., the crystallographic texture of the bulk sheet) have been taken into account. So far, there has been no model for the prediction of the strain path and the limit strain of sheet metals that takes into account the effect of individual grain orientation and the dislocation property. In this thesis, different approaches in the study of plastic deformation are reviewed from the view-point of both macroplasticity and microplasticity. Instead of relying on a unique flow rule to describe the stress and strain relationship, the role of work hardening in the instability process of sheet metal and hence the flow localization phenomenon is explored from a study of the changes in the orientation of the constituent crystallites and from the changes in the dislocation density associated with different grain orientations during the course of large biaxial deformation. The changes in the crystallographic textures of an aluminium sheet sample deformed under various stress states from plane-strain tension to equi

  6. Crystal growth and first crystallographic characterization of mixed uranium(IV)-plutonium(III) oxalates.

    Science.gov (United States)

    Tamain, Christelle; Arab Chapelet, Bénédicte; Rivenet, Murielle; Abraham, Francis; Caraballo, Richard; Grandjean, Stéphane

    2013-05-06

    The mixed-actinide uranium(IV)-plutonium(III) oxalate single crystals (NH4)0.5[Pu(III)0.5U(IV)0.5(C2O4)2·H2O]·nH2O (1) and (NH4)2.7Pu(III)0.7U(IV)1.3(C2O4)5·nH2O (2) have been prepared by the diffusion of different ions through membranes separating compartments of a triple cell. UV-vis, Raman, and thermal ionization mass spectrometry analyses demonstrate the presence of both uranium and plutonium metal cations with conservation of the initial oxidation state, U(IV) and Pu(III), and the formation of mixed-valence, mixed-actinide oxalate compounds. The structure of 1 and an average structure of 2 were determined by single-crystal X-ray diffraction and were solved by direct methods and Fourier difference techniques. Compounds 1 and 2 are the first mixed uranium(IV)-plutonium(III) compounds to be structurally characterized by single-crystal X-ray diffraction. The structure of 1, space group P4/n, a = 8.8558(3) Å, b = 7.8963(2) Å, Z = 2, consists of layers formed by four-membered rings of the two actinide metals occupying the same crystallographic site connected through oxalate ions. The actinide atoms are nine-coordinated by oxygen atoms from four bidentate oxalate ligands and one water molecule, which alternates up and down the layer. The single-charged cations and nonbonded water molecules are disordered in the same crystallographic site. For compound 2, an average structure has been determined in space group P6/mmm with a = 11.158(2) Å and c = 6.400(1) Å. The honeycomb-like framework [Pu(III)0.7U(IV)1.3(C2O4)5](2.7-) results from a three-dimensional arrangement of mixed (U0.65Pu0.35)O10 polyhedra connected by five bis-bidentate μ(2)-oxalate ions in a trigonal-bipyramidal configuration.

  7. PPARγ-Independent Mechanism

    Directory of Open Access Journals (Sweden)

    Christopher M. Hogan

    2011-01-01

    Full Text Available Acute and chronic lung inflammation is associated with numerous important disease pathologies including asthma, chronic obstructive pulmonary disease and silicosis. Lung fibroblasts are a novel and important target of anti-inflammatory therapy, as they orchestrate, respond to, and amplify inflammatory cascades and are the key cell in the pathogenesis of lung fibrosis. Peroxisome proliferator-activated receptor gamma (PPARγ ligands are small molecules that induce anti-inflammatory responses in a variety of tissues. Here, we report for the first time that PPARγ ligands have potent anti-inflammatory effects on human lung fibroblasts. 2-cyano-3, 12-dioxoolean-1, 9-dien-28-oic acid (CDDO and 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2 inhibit production of the inflammatory mediators interleukin-6 (IL-6, monocyte chemoattractant protein-1 (MCP-1, COX-2, and prostaglandin (PGE2 in primary human lung fibroblasts stimulated with either IL-1β or silica. The anti-inflammatory properties of these molecules are not blocked by the PPARγ antagonist GW9662 and thus are largely PPARγ independent. However, they are dependent on the presence of an electrophilic carbon. CDDO and 15d-PGJ2, but not rosiglitazone, inhibited NF-κB activity. These results demonstrate that CDDO and 15d-PGJ2 are potent attenuators of proinflammatory responses in lung fibroblasts and suggest that these molecules should be explored as the basis for novel, targeted anti-inflammatory therapies in the lung and other organs.

  8. Media independence and dividend policy

    DEFF Research Database (Denmark)

    Farooq, Omar; Dandoune, Salma

    2012-01-01

    independence and dividend policies in emerging markets. Using a dataset from twenty three emerging markets, we show a significantly negative relationship between dividend policies (payout ratio and decision to pay dividend) and media independence. We argue that independent media reduces information asymmetries...... for stock market participants. Consequently, stock market participants in emerging markets with more independent media do not demand as high and as much dividends as their counterparts in emerging markets with less independent media. We also show that press independence is more important in defining......Can media pressurize managers to disgorge excess cash to shareholders? Do firms in countries with more independent media follow different dividend policies than firms with less independent media? This paper seeks to answer these questions and aims to document the relationship between media...

  9. Media independence and dividend policy

    DEFF Research Database (Denmark)

    Farooq, Omar; Dandoune, Salma

    2012-01-01

    for stock market participants. Consequently, stock market participants in emerging markets with more independent media do not demand as high and as much dividends as their counterparts in emerging markets with less independent media. We also show that press independence is more important in defining...... independence and dividend policies in emerging markets. Using a dataset from twenty three emerging markets, we show a significantly negative relationship between dividend policies (payout ratio and decision to pay dividend) and media independence. We argue that independent media reduces information asymmetries......Can media pressurize managers to disgorge excess cash to shareholders? Do firms in countries with more independent media follow different dividend policies than firms with less independent media? This paper seeks to answer these questions and aims to document the relationship between media...

  10. Independent sets in chain cacti

    OpenAIRE

    Sedlar, Jelena

    2011-01-01

    In this paper chain cacti are considered. First, for two specific classes of chain cacti (orto-chains and meta-chains of cycles with h vertices) the recurrence relation for independence polynomial is derived. That recurrence relation is then used in deriving explicit expressions for independence number and number of maximum independent sets for such chains. Also, the recurrence relation for total number of independent sets for such graphs is derived. Finaly, the proof is provided that orto-ch...

  11. Crystallographic orientation and electrode nature are key factors for electric current generation by Geobacter sulfurreducens.

    Science.gov (United States)

    Maestro, Beatriz; Ortiz, Juan M; Schrott, Germán; Busalmen, Juan P; Climent, Víctor; Feliu, Juan M

    2014-08-01

    We have investigated the influence of electrode material and crystallographic structure on electron transfer and biofilm formation of Geobacter sulfurreducens. Single-crystal gold-Au(110), Au(111), Au(210)-and platinum-Pt(100), Pt(110), Pt(111), Pt(210)-electrodes were tested and compared to graphite rods. G. sulfurreducens electrochemically interacts with all these materials with different attachment kinetics and final current production, although redox species involved in the electron transfer to the anode are virtually the same in all cases. Initial bacterial colonization was fastest on graphite up to the monolayer level, whereas gold electrodes led to higher final current densities. Crystal geometry was shown to have an important influence, with Au(210) sustaining a current density of up to 1442±101μAcm(-2) at the steady state, over Au(111) with 961±94μAcm(-2) and Au(110) with 944±89μAcm(-2). On the other hand, the platinum electrodes displayed the lowest performances, including Pt(210). Our results indicate that both crystal geometry and electrode material are key parameters for the efficient interaction of bacteria with the substrate and should be considered for the design of novel materials and microbial devices to optimize energy production.

  12. Synthetic, crystallographic, and computational study of copper(II) complexes of ethylenediaminetetracarboxylate ligands.

    Science.gov (United States)

    Matović, Zoran D; Miletić, Vesna D; Ćendić, Marina; Meetsma, Auke; van Koningsbruggen, Petra J; Deeth, Robert J

    2013-02-04

    Copper(II) complexes of hexadentate ethylenediaminetetracarboxylic acid type ligands H(4)eda3p and H(4)eddadp (H(4)eda3p = ethylenediamine-N-acetic-N,N',N'-tri-3-propionic acid; H(4)eddadp = ethylenediamine-N,N'-diacetic-N,N'-di-3-propionic acid) have been prepared. An octahedral trans(O(6)) geometry (two propionate ligands coordinated in axial positions) has been established crystallographically for the Ba[Cu(eda3p)]·8H(2)O compound, while Ba[Cu(eddadp)]·8H(2)O is proposed to adopt a trans(O(5)) geometry (two axial acetates) on the basis of density functional theory calculations and comparisons of IR and UV-vis spectral data. Experimental and computed structural data correlating similar copper(II) chelate complexes have been used to better understand the isomerism and departure from regular octahedral geometry within the series. The in-plane O-Cu-N chelate angles show the smallest deviation from the ideal octahedral value of 90°, and hence the lowest strain, for the eddadp complex with two equatorial β-propionate rings. A linear dependence between tetragonality and the number of five-membered rings has been established. A natural bonding orbital analysis of the series of complexes is also presented.

  13. On elliptic Calogero-Moser systems for complex crystallographic reflection groups

    CERN Document Server

    Etingof, Pavel; Ma, Xiaoguang; Veselov, Alexander

    2010-01-01

    To every irreducible finite crystallographic reflection group (i.e., an irreducible finite reflection group G acting faithfully on an abelian variety X), we attach a family of classical and quantum integrable systems on X (with meromorphic coefficients). These families are parametrized by G-invariant functions of pairs (T,s), where T is a hypertorus in X (of codimension 1), and s in G is a reflection acting trivially on T. If G is a real reflection group, these families reduce to the known generalizations of elliptic Calogero-Moser systems, but in the non-real case they appear to be new. We give two constructions of the integrals of these systems - an explicit construction as limits of classical Calogero-Moser Hamiltonians of elliptic Dunkl operators as the dynamical parameter goes to 0 (implementing an idea of arXiv:hep-th/9403178), and a geometric construction as global sections of sheaves of elliptic Cherednik algebras for the critical value of the twisting parameter. We also prove algebraic integrability ...

  14. Surface energy-mediated construction of anisotropic semiconductor wires with selective crystallographic polarity

    Science.gov (United States)

    Sohn, Jung Inn; Hong, Woong-Ki; Lee, Sunghoon; Lee, Sanghyo; Ku, Jiyeon; Park, Young Jun; Hong, Jinpyo; Hwang, Sungwoo; Park, Kyung Ho; Warner, Jamie H.; Cha, Seungnam; Kim, Jong Min

    2014-07-01

    ZnO is a wide band-gap semiconductor with piezoelectric properties suitable for opto-electronics, sensors, and as an electrode material. Controlling the shape and crystallography of any semiconducting nanomaterial is a key step towards extending their use in applications. Whilst anisotropic ZnO wires have been routinely fabricated, precise control over the specific surface facets and tailoring of polar and non-polar growth directions still requires significant refinement. Manipulating the surface energy of crystal facets is a generic approach for the rational design and growth of one-dimensional (1D) building blocks. Although the surface energy is one basic factor for governing crystal nucleation and growth of anisotropic 1D structures, structural control based on surface energy minimization has not been yet demonstrated. Here, we report an electronic configuration scheme to rationally modulate surface electrostatic energies for crystallographic-selective growth of ZnO wires. The facets and orientations of ZnO wires are transformed between hexagonal and rectangular/diamond cross-sections with polar and non-polar growth directions, exhibiting different optical and piezoelectrical properties. Our novel synthetic route for ZnO wire fabrication provides new opportunities for future opto-electronics, piezoelectronics, and electronics, with new topological properties.

  15. Expression, purification, crystallization and preliminary crystallographic analysis of the proliferation-associated protein Ebp1

    Energy Technology Data Exchange (ETDEWEB)

    Kowalinski, Eva; Bange, Gert; Wild, Klemens; Sinning, Irmgard, E-mail: irmi.sinning@bzh.uni-heidelberg.de [Heidelberg University Biochemistry Center, INF 328, D-69120 Heidelberg (Germany)

    2007-09-01

    Preliminary X-ray analysis of the proliferation-associated protein Ebp1 from Homo sapiens is provided. ErbB-3-binding protein 1 (Ebp1) is a member of the family of proliferation-associated 2G4 proteins (PA2G4s) and plays a role in cellular growth and differentiation. Ligand-induced activation of the transmembrane receptor ErbB3 leads to dissociation of Ebp1 from the receptor in a phosphorylation-dependent manner. The non-associated protein is involved in transcriptional and translational regulation in the cell. Here, the overexpression, purification, crystallization and preliminary crystallographic studies of Ebp1 from Homo sapiens are reported. Initially observed crystals were improved by serial seeding to single crystals suitable for data collection. The optimized crystals belong to the tetragonal space group P4{sub 1}2{sub 1}2 or P4{sub 3}2{sub 1}2 and diffracted to a resolution of 1.6 Å.

  16. Protein structure prediction provides comparable performance to crystallographic structures in docking-based virtual screening.

    Science.gov (United States)

    Du, Hongying; Brender, Jeffrey R; Zhang, Jian; Zhang, Yang

    2015-01-01

    Structure based virtual screening has largely been limited to protein targets for which either an experimental structure is available or a strongly homologous template exists so that a high-resolution model can be constructed. The performance of state of the art protein structure predictions in virtual screening in systems where only weakly homologous templates are available is largely untested. Using the challenging DUD database of structural decoys, we show here that even using templates with only weak sequence homology (identity) structural models can be constructed by I-TASSER which achieve comparable enrichment rates to using the experimental bound crystal structure in the majority of the cases studied. For 65% of the targets, the I-TASSER models, which are constructed essentially in the apo conformations, reached 70% of the virtual screening performance of using the holo-crystal structures. A correlation was observed between the success of I-TASSER in modeling the global fold and local structures in the binding pockets of the proteins versus the relative success in virtual screening. The virtual screening performance can be further improved by the recognition of chemical features of the ligand compounds. These results suggest that the combination of structure-based docking and advanced protein structure modeling methods should be a valuable approach to the large-scale drug screening and discovery studies, especially for the proteins lacking crystallographic structures.

  17. Crystallographic and Computational Analyses of AUUCU Repeating RNA That Causes Spinocerebellar Ataxia Type 10 (SCA10).

    Science.gov (United States)

    Park, HaJeung; González, Àlex L; Yildirim, Ilyas; Tran, Tuan; Lohman, Jeremy R; Fang, Pengfei; Guo, Min; Disney, Matthew D

    2015-06-23

    Spinocerebellar ataxia type 10 (SCA10) is caused by a pentanucleotide repeat expansion of r(AUUCU) within intron 9 of the ATXN10 pre-mRNA. The RNA causes disease by a gain-of-function mechanism in which it inactivates proteins involved in RNA biogenesis. Spectroscopic studies showed that r(AUUCU) repeats form a hairpin structure; however, there were no high-resolution structural models prior to this work. Herein, we report the first crystal structure of model r(AUUCU) repeats refined to 2.8 Å and analysis of the structure via molecular dynamics simulations. The r(AUUCU) tracts adopt an overall A-form geometry in which 3 × 3 nucleotide (5')UCU(3')/(3')UCU(5') internal loops are closed by AU pairs. Helical parameters of the refined structure as well as the corresponding electron density map on the crystallographic model reflect dynamic features of the internal loop. The computational analyses captured dynamic motion of the loop closing pairs, which can form single-stranded conformations with relatively low energies. Overall, the results presented here suggest the possibility for r(AUUCU) repeats to form metastable A-from structures, which can rearrange into single-stranded conformations and attract proteins such as heterogeneous nuclear ribonucleoprotein K (hnRNP K). The information presented here may aid in the rational design of therapeutics targeting this RNA.

  18. Scattering of slow ions by various crystallographic planes of tungsten single crystals

    CERN Document Server

    Ermolov, S N; Kortenraad, R; Must, B; Shtinov, E D; Brongersma, K K

    2002-01-01

    The dependence of low-energy ion scattering signal intensity on single crystal surface orientation is investigated, and it is shown that this dependence is not necessarily in direct proportion to atomic density in the uppermost atomic layer. On the basis of comparison of signals from various crystallographic planes of a high purity W single crystal a conclusion is made that the ions scattered from more deep atomic layers contribute considerably to the signal measured for the surface with an open structure. It is shown that reference specimens with a known surface density are needed for quantitative analysis of surface composition by the method of low-energy ion scattering. The best reference specimens are well-oriented single crystals with close-packed planes at the surface, since in this case the low-energy ion scattering signal is proportional to atomic density of the uppermost atomic layer. It single crystals with open surface structure are used as reference specimens the contribution of deeper atomic laye...

  19. CRYSTALLOGRAPHIC RELATIONS OF CEMENTITE–AUSTENITE–FERRITE IN THE DIFFUSIVE DECOMPOSITION OF AUSTENITE

    Directory of Open Access Journals (Sweden)

    BOLSHAKOV V. I.

    2016-05-01

    Full Text Available Summary. It was made a search for new and more accurate orientation relations between the crystal lattice in the pearlite and bainite austenite decomposition products. Methods. It were used the methods: transmission electron microscopy, the micro-, mathematical matrix and stereographic analysis. The purpose of the research is with theoretical, numerical and experimental methods to set up to a 0.2 degree angular orientation relations between the lattices of ferrite and cementite in the austenite decomposition products in the temperature range 400 ... 700С. Results. It was established a new, refined value for grids in the diffusion decay of γ → α + (α + θ. Practical significance. It was proposed a new oriented dependence and the corresponding double gnomonic projection with poles to planes α and θ phases, which can be used in patterns of crystallographic lattices relations studies at phase transitions, as well as the subsequent modeling of complex physical processes of structure formation in metals and binary systems.

  20. Changes of structure and crystallographic texture of cladding tubes from austenitic steel under thermal creep testing

    Science.gov (United States)

    Perlovich, Yu; Isaenkova, M.; Fesenko, V.; Dobrokhotov, P.; Tselishchev, A.

    2016-04-01

    The process of changes in structure and crystallographic texture of cladding tubes from austenitic steel ChS68 under thermal creep testing were studied. Testing of tubes was conducted at the temperature 700 oC in the air by their stretching in axial direction under the stress 160 MPa until rupture. By data of phase and texture analysis a number of processes, accompanying plastic deformation of tubes during thermal creep tests at elevated temperature, were identified. The main texture components of original tube, as well as texture components of different parts of the tested tube are {110} and {112}. In the rupture zone the component of the texture of tension with axis along the tube axis becomes stronger. This effect is connected with activation of dislocation slip in the deformed area of tested tube near the new-formed neck. At the same time the character of texture changes in the zone of tube rupture indicates to development of the dynamic recrystallization, conditioned by the total influence of all factors, which control the passage in the tube of thermal creep. In addition, it was revealed the activation of martensitic transformations in the zone of maximal deformation of tube as a result of its creep tests.

  1. Reintroducing electrostatics into macromolecular crystallographic refinement: application to neutron crystallography and DNA hydration.

    Science.gov (United States)

    Fenn, Timothy D; Schnieders, Michael J; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S; Brunger, Axel T

    2011-04-13

    Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints, and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here, we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a protein crystal structure were refined against joint neutron/X-ray diffraction data sets using force fields without electrostatics or with electrostatics. Hydrogen-bond orientation/geometry favors the inclusion of electrostatics. Refinement of Z-DNA with electrostatics leads to a hypothesis for the entropic stabilization of Z-DNA that may partly explain the thermodynamics of converting the B form of DNA to its Z form. Thus, inclusion of electrostatics assists joint neutron/X-ray refinements, especially for placing and orienting hydrogen atoms.

  2. Protein crystallography for aspiring crystallographers or how to avoid pitfalls and traps in macromolecular structure determination.

    Science.gov (United States)

    Wlodawer, Alexander; Minor, Wladek; Dauter, Zbigniew; Jaskolski, Mariusz

    2013-11-01

    The number of macromolecular structures deposited in the Protein Data Bank now approaches 100,000, with the vast majority of them determined by crystallographic methods. Thousands of papers describing such structures have been published in the scientific literature, and 20 Nobel Prizes in chemistry or medicine have been awarded for discoveries based on macromolecular crystallography. New hardware and software tools have made crystallography appear to be an almost routine (but still far from being analytical) technique and many structures are now being determined by scientists with very limited experience in the practical aspects of the field. However, this apparent ease is sometimes illusory and proper procedures need to be followed to maintain high standards of structure quality. In addition, many noncrystallographers may have problems with the critical evaluation and interpretation of structural results published in the scientific literature. The present review provides an outline of the technical aspects of crystallography for less experienced practitioners, as well as information that might be useful for users of macromolecular structures, aiming to show them how to interpret (but not overinterpret) the information present in the coordinate files and in their description. A discussion of the extent of information that can be gleaned from the atomic coordinates of structures solved at different resolution is provided, as well as problems and pitfalls encountered in structure determination and interpretation.

  3. A new systematic framework for crystallographic analysis of atom probe data

    Energy Technology Data Exchange (ETDEWEB)

    Araullo-Peters, Vicente J., E-mail: vicente.araullopeters@gmail.com [Australian Centre for Microscopy and Microanalysis, University of Sydney (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney (Australia); Breen, Andrew; Ceguerra, Anna V. [Australian Centre for Microscopy and Microanalysis, University of Sydney (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney (Australia); Gault, Baptiste [Department of Materials, University of Oxford, Parks Road, Oxford (United Kingdom); Ringer, Simon P.; Cairney, Julie M. [Australian Centre for Microscopy and Microanalysis, University of Sydney (Australia); School of Aerospace, Mechanical and Mechatronic Engineering, University of Sydney (Australia)

    2015-07-15

    In this article, after a brief introduction to the principles behind atom probe crystallography, we introduce methods for unambiguously determining the presence of crystal planes within atom probe datasets, as well as their characteristics: location; orientation and interplanar spacing. These methods, which we refer to as plane orientation extraction (POE) and local crystallography mapping (LCM) make use of real-space data and allow for systematic analyses. We present here application of POE and LCM to datasets of pure Al, industrial aluminium alloys and doped-silicon. Data was collected both in DC voltage mode and laser-assisted mode (in the latter of which extracting crystallographic information is known to be more difficult due to distortions). The nature of the atomic planes in both datasets was extracted and analysed. - Highlights: • A new analysis method was designed that determines if reconstructed planes are present in atom probe data. • The location, orientation, and planar spacing of these planes are obtained. • This method was applied to simulated, aluminium alloy and silicon data where the extent of planes was shown to vary considerably. • This method can be used to examine atom probe reconstruction quality.

  4. Microstructures and crystallographic preferred orientation of anorthosites from Oman ophiolite and the dynamics of melt lenses

    Science.gov (United States)

    Morales, Luiz F. G.; Boudier, FrançOise; Nicolas, Adolphe

    2011-04-01

    Microstructures and crystallographic preferred orientation (CPO) of anorthosite samples interlayered in the upper and lower gabbro sections in the Oman ophiolite were analyzed in this paper. In the anorthosites registering the dynamics of the melt lenses, foliation is flat lying and starts to develop a few meters below the root zone of the sheeted dike complex (RZSDC). Microstructures and CPO of these rocks were developed in response to four different mechanisms: (1) density-controlled settling of plagioclase on the lens floor, (2) deposition of anorthosites related to convection currents, (3) melt compaction, and (4) uncompacted melt accumulation. In these anorthosites, the poles to (010) of plagioclase are parallel to the flow plane of convection, whereas the [100] axes and poles to (001) express the convection flow direction and the axis of convection rolls, respectively. The effect of subsidence of melt lens floor is recorded immediately below the RZSDC and is characterized by the rapid (but progressive) development of dipping foliation and lineation, reflecting the increase of deformation downsection. The degree of foliation and CPO development in the anorthosites is directly related to the distance of the center of the melt lenses before the subsidence starts. Despite the uncertain origin of the anorthosites from the lower gabbro section, all the samples lost the magmatic microstructural characteristics and presently are reequilibrated aggregates. However, they still preserve plagioclase CPO, where some of these patterns present similarities with the anorthosites from the upper gabbro section, but no evidence of intracrystalline deformation under high temperatures.

  5. Purification and crystallographic analysis of a FAD-dependent halogenase from Streptomyces sp. JCM9888.

    Science.gov (United States)

    Zhao, Yanqun; Yan, Baohua; Yang, Ting; Jiang, Jian; Wei, Heng; Zhu, Xiaofeng

    2015-08-01

    A new FAD (flavin adenine dinucleotide)-dependent halogenase HalY from Streptomyces sp. JCM9888 was reported to be involved in the regioselective halogenation of adenine. HalY is a variant B FAD-dependent halogenase that is most similar to the halogenase PltA involved in pyoluteorin biosynthesis. This study reports the overexpression and purification of HalY with an N-terminal hexahistidine tag, followed by crystallization experiments and X-ray crystallographic analysis. HalY was purified as a monomer in solution and crystallized to give X-ray diffraction to a resolution of 1.7 Å. The crystal belonged to the monoclinic space group P21, with unit-cell parameters a = 41.4, b = 113.4, c = 47.6 Å, α = γ = 90, β = 107.4°, and contained one monomer of HalY in the asymmetric unit, with a calculated Matthews coefficient of 2.3 Å(3) Da(-1) and a solvent content of 46%. The structure of the halogenase CndH was used as a search model in molecular replacement to obtain the initial model of HalY. Manual model building and structure refinement of HalY are in progress.

  6. Studying the Independent School Library

    Science.gov (United States)

    Cahoy, Ellysa Stern; Williamson, Susan G.

    2008-01-01

    In 2005, the American Association of School Librarians' Independent Schools Section conducted a national survey of independent school libraries. This article analyzes the results of the survey, reporting specialized data and information regarding independent school library budgets, collections, services, facilities, and staffing. Additionally, the…

  7. Crystallographic analysis of TPP riboswitch binding by small-molecule ligands discovered through fragment-based drug discovery approaches.

    Science.gov (United States)

    Warner, Katherine Deigan; Ferré-D'Amaré, Adrian R

    2014-01-01

    Riboswitches are structured mRNA elements that regulate gene expression in response to metabolite or second-messenger binding and are promising targets for drug discovery. Fragment-based drug discovery methods have identified weakly binding small molecule "fragments" that bind a thiamine pyrophosphate (TPP) riboswitch. However, these fragments require substantial chemical elaboration into more potent, drug-like molecules. Structure determination of the fragments bound to the riboswitch is the necessary next step. In this chapter, we describe the methods for co-crystallization and structure determination of fragment-bound TPP riboswitch structures. We focus on considerations for screening crystallization conditions across multiple crystal forms and provide guidance for building the fragment into the refined crystallographic model. These methods are broadly applicable for crystallographic analyses of any small molecules that bind structured RNAs.

  8. Glassy Carbon Electrode-Supported Au Nanoparticles for the Glucose Electrooxidation: On the Role of Crystallographic Orientation

    Directory of Open Access Journals (Sweden)

    M. Guerra-Balcázar

    2012-01-01

    Full Text Available Glucose electrooxidation in alkaline solution was examined using glassy carbon electrodes modified with Au nanoparticles. Au nanoparticles were prepared following the two-phase protocol and characterized by transmission electron microscopy (TEM, UV-Vis spectroscopy, X-ray diffraction spectroscopy (XRD, and cyclic voltammetry (CV. It was found that, under the study conditions, it is possible to obtain nanoparticles between 1 and 5 nm; also it was found that the crystallographic orientation is strongly influenced by the ratio metal/thiol and to a lesser extent by the synthesis temperature. The voltammetric response for the electrocatalytic oxidation of glucose at carbon Au nanoparticle-modified electrode shows an increasing activity with nanoparticles size. Electroactivity and possibly selectivity are found to be nanoparticles' crystallographic orientation dependent. Classical electrochemical analysis shows that glucose electrooxidation is a diffusion-controlled process followed by a homogenous reaction.

  9. Crystallographic Features and State Stability of the Decagonal Quasicrystal in the Al-Co-Cu Alloy System

    Science.gov (United States)

    Nakayama, Kei; Mizutani, Akito; Koyama, Yasumasa

    2016-11-01

    In the Al-Co-Cu alloy system, both the decagonal quasicrystal with the space group of Poverline{10}m2 and its approximant Al13Co4 phase with monoclinic Cm symmetry are present around 20 at. % Co-10 at. % Cu. In this study, we examined the crystallographic features of prepared Al-(30 - x) at. % Co-x at. % Cu samples mainly by transmission electron microscopy in order to make clear the crystallographic relation between the decagonal quasicrystal and the monoclinic Al13Co4 structure. The results revealed a coexistence state consisting of decagonal quasicrystal and approximant Al13Co4 regions in Al-20 at. % Co-10 at. % Cu alloy samples. With the help of the coexistence state, the orientation relationship was established between the monoclinic Al13Co4 structure and the decagonal quasicrystal. In the determined relationship, the crystallographic axis in the quasicrystal was found to be parallel to the normal direction of the (010)m plane in the Al13Co4 structure, where the subscript m denotes the monoclinic system. Based on data obtained experimentally, the state stability of the decagonal quasicrystal was also examined in terms of the Hume-Rothery (HR) mechanism on the basis of the nearly-free-electron approximation. It was found that a model based on the HR mechanism could explain the crystallographic features such as electron diffraction patterns and atomic arrangements found in the decagonal quasicrystal. In other words, the HR mechanism is most likely appropriate for the stability of the decagonal quasicrystal in the Al-Co-Cu alloy system.

  10. The fcc-bcc crystallographic orientation relationship in AlxCoCrFeNi high-entropy alloys

    NARCIS (Netherlands)

    Rao, J. C.; Ocelik, V.; Vainchtein, D.; Tang, Z.; Liaw, P. K.; De Hosson, J. Th. M.

    2016-01-01

    This paper concentrates on the crystallographic-orientation relationship between the various phases in the Al-Co-Cr-Fe-Ni high-entropy alloys. Two types of orientation relationships of bcc phases (some with ordered B2 structures) and fcc matrix were observed in Al0.5CoCrFeNi and Al0.7CoCrFeNi alloys

  11. Self-Assembled Monolayers: Star-Shaped Crystallographic Cracking of Localized Nanoporous Defects (Adv. Mater. 33/2015).

    Science.gov (United States)

    Renner, Frank Uwe; Ankah, Genesis Ngwa; Bashir, Asif; Ma, Duancheng; Biedermann, P Ulrich; Shrestha, Buddha Ratna; Nellessen, Monika; Khorashadizadeh, Anahita; Losada-Pérez, Patricia; Duarte, Maria Jazmin; Raabe, Dierk; Valtiner, Markus

    2015-09-02

    On page 4877, F. U. Renner, A. Bashir, M. Valtiner, and co-workers describe a star-like dealloying corrosion morphology that appears during the localized attack of smooth well-prepared Cu-Au surfaces. The surfaces are initially protected by thiol or selenol inhibitior films. Localized dealloying of Cu-Au produces nanoporous gold under stress and crystallographic cracks - thereby opening a new approach combining surface science with nanoscale mechanical testing.

  12. A numerical investigation of grain shape and crystallographic texture effects on the plastic strain localization in friction stir weld zones

    Science.gov (United States)

    Romanova, V.; Balokhonov, R.; Batukhtina, E.; Shakhidjanov, V.

    2015-10-01

    Crystal plasticity approaches were adopted to build models accounting for the microstructure and texture observed in different friction stir weld zones. To this end, a numerical investigation of crystallographic texture and grain shape effects on the plastic strain localization in a friction stir weld of an aluminum-base alloy was performed. The presence of texture was found to give rise to pronounced mesoscale plastic strain localization.

  13. Independent sets in chain cacti

    CERN Document Server

    Sedlar, Jelena

    2011-01-01

    In this paper chain cacti are considered. First, for two specific classes of chain cacti (orto-chains and meta-chains of cycles with h vertices) the recurrence relation for independence polynomial is derived. That recurrence relation is then used in deriving explicit expressions for independence number and number of maximum independent sets for such chains. Also, the recurrence relation for total number of independent sets for such graphs is derived. Finaly, the proof is provided that orto-chains and meta-chains are the only extremal chain cacti with respect to total number of independent sets (orto-chains minimal and meta-chains maximal).

  14. Recombinant production, crystallization and X-ray crystallographic structure determination of the peptidyl-tRNA hydrolase of Pseudomonas aeruginosa

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, Ronny C.; McFeeters, Hana; Coates, Leighton; McFeeters, Robert L.

    2014-10-15

    The peptidyl-tRNA hydrolase enzyme from the pathogenic bacterium Pseudomonas aeruginosa (Pth; EC 3.1.1.29) has been cloned, expressed in Escherichia coli and crystallized for X-ray structural analysis. Suitable crystals were grown using the sitting-drop vapour-diffusion method after one week of incubation against a reservoir solution consisting of 20% polyethylene glycol 4000, 100 mM Tris pH 7.5, 10%(v/v) isopropyl alcohol. The crystals were used to obtain the three-dimensional structure of the native protein at 1.77 Å resolution. The structure was determined by molecular replacement of the crystallographic data processed in space group P6122 with unit-cell parameters a = b = 63.62,c = 155.20 Å, α = β = 90, γ = 120°. The asymmetric unit of the crystallographic lattice was composed of a single copy of the enzyme molecule with a 43% solvent fraction, corresponding to a Matthews coefficient of 2.43 Å3 Da-1. The crystallographic structure reported here will serve as the foundation for future structure-guided efforts towards the development of novel small-molecule inhibitors specific to bacterial Pths.

  15. Coupled Crystal Plasticity-Phase Field Fracture Simulation Study on Damage Evolution Around a Void: Pore Shape Versus Crystallographic Orientation

    Science.gov (United States)

    Diehl, Martin; Wicke, Marcel; Shanthraj, Pratheek; Roters, Franz; Brueckner-Foit, Angelika; Raabe, Dierk

    2017-03-01

    Various mechanisms such as anisotropic plastic flow, damage nucleation, and crack propagation govern the overall mechanical response of structural materials. Understanding how these mechanisms interact, i.e. if they amplify mutually or compete with each other, is an essential prerequisite for the design of improved alloys. This study shows—by using the free and open source software DAMASK (the Düsseldorf Advanced Material Simulation Kit)—how the coupling of crystal plasticity and phase field fracture methods can increase the understanding of the complex interplay between crystallographic orientation and the geometry of a void. To this end, crack initiation and propagation around an experimentally obtained pore with complex shape is investigated and compared to the situation of a simplified spherical void. Three different crystallographic orientations of the aluminum matrix hosting the defects are considered. It is shown that crack initiation and propagation depend in a non-trivial way on crystallographic orientation and its associated plastic behavior as well as on the shape of the pore.

  16. The effect of magnetic annealing on crystallographic texture and magnetic properties of Fe-2.6% Si

    Energy Technology Data Exchange (ETDEWEB)

    Salih, M.Z., E-mail: mohammedzs2007@hotmail.com [Institut für Werkstoffkunde und Werkstofftechnik, TU Clausthal, Agricolastraße 6, D-38678 Clausthal-Zellerfeld (Germany); Uhlarz, M. [Dresden High Magnetic Field Laboratory (HLD), Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, D-01328 Dresden (Germany); Pyczak, F. [Instiute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Brokmeier, H.-G. [Institut für Werkstoffkunde und Werkstofftechnik, TU Clausthal, Agricolastraße 6, D-38678 Clausthal-Zellerfeld (Germany); Instiute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Weidenfeller, B. [Institut für Elektrochemie, Abteilung für Materialwissenschaft, Arnold-Sommerfeld-Straße 6, D-38678 Clausthal-Zellerfeld (Germany); Al-hamdany, N. [Institut für Werkstoffkunde und Werkstofftechnik, TU Clausthal, Agricolastraße 6, D-38678 Clausthal-Zellerfeld (Germany); Gan, W.M. [Instiute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany); Zhong, Z.Y. [Institut für Werkstoffkunde und Werkstofftechnik, TU Clausthal, Agricolastraße 6, D-38678 Clausthal-Zellerfeld (Germany); Schell, N. [Instiute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Straße 1, D-21502 Geesthacht (Germany)

    2015-05-01

    The effect of magnetic annealing on crystallographic texture, microstructure, defects density and magnetic properties of a Fe-2.6% Si steel has been analyzed. After two stage cold rolling (75% and 60% cold rolled) with intermediate annealing process at (600 °C/1 h) the sample annealed at 600 °C for one hour during which different magnetic field of 0, 7 and 14 T were applied has been investigated. The effect of defects density after cold rolling process on the recrystallization texture and magnetic properties was characterized. Heat treatments under a high external field of 14 T show a drastic improvement of the magnetic properties such as significantly increased permeability. Neutron diffraction measurements were preferred for measurement of the bulk sample texture so that sufficient grain statistics were obtained. Because of its small wavelength (0.05–0.2 Å) Synchrotron diffraction with high photon energy was used to evaluate the defects density by a modified Williamson–Hall plot. - Highlights: • We show the effect of the magnetic annealing after intermediate cold rolling on the crystallographic texture and magnetic properties. • Due the coarse grained we used Neutron diffraction for texture measurement. • We used hysteresis recorder to measure the magnetic properties. • The magnetic annealing leads to drastic improvements of the magnetic properties such as significantly increased permeability. • We show the effect of defect density on the crystallographic texture and magnetic properties.

  17. Diaqua-bis-[bis-(pyrazin-2-yl) sulfide-κN (4)]bis-(thio-cyanato-κN)iron(II) monohydrate

    National Research Council Canada - National Science Library

    Wöhlert, Susanne; Jess, Inke; Näther, Christian

    2013-01-01

    ...) sulfide ligands and two water mol-ecules in an slightly distorted octa-hedral geometry. The Fe(II) cation is located on a center of inversion and the lattice water mol-ecule on a twofold rotation axis...

  18. Crystallographic control on early stages of cataclasis in carbonate fault gouges

    Science.gov (United States)

    Demurtas, Matteo; Smith, Steven A. F.; Fondriest, Michele; Spagnuolo, Elena; Di Toro, Giulio

    2017-04-01

    Carbonates are a recurring lithology in most of active seismic areas worldwide, such as the Apennines (Italy). Here, typical fault products are gouges and cataclasites made of mixtures of carbonate minerals (i.e., calcite and dolomite) that occasionally exhibit a foliation. Natural fault gouges often contain minerals with strong anisotropies, such as cleavage surfaces in phyllosilicates and carbonates. Therefore, the understanding of the role of such anisotropies during shearing is important to develop realistic microphysical models of brittle fragmentation and grain size reduction. Here we present results of microstructural and coupled EDS-EBSD (Energy Dispersive Spectroscopy - Electron Backscattered Diffraction) analysis on mixtures (50/50wt%) of calcite-dolomite gouges deformed experimentally in a rotary shear apparatus (SHIVA, INGV-Rome) at room temperature under constant normal stress of 17.5 MPa and slip rates of 30 µm/s to 1 m/s. The EDS-EBSD analysis was focused on the gouge layer underlying the slip zone, which has been previously demonstrated to accommodate low finite shear strain during deformation. At all investigated slip rates, calcite develops a crystallographic preferred orientation (CPO) on the (0001) plane, with the c-axis inclined subparallel to the principal stress and the [-1-120] direction forming a girdle perpendicular to it. Texture strength typically increases with slip rate and appears not to be influenced by the presence of water or foliation development in the gouge during deformation. Misorientation analysis suggests twinning as the principal crystallographic active deformation mechanism. Instead, dolomite grains do not develop a CPO. Microfractures are closely spaced, mainly oriented subparallel to the principal stress and rarely exploit calcite twin planes. The latter typically occur at high angle with respect to fractures, are oriented consistently with the sense of shear and almost orthogonal to the principal stress. Calcite grains

  19. Phosphate tungsten bronze series: crystallographic and structural properties of low-dimensional conductors.

    Science.gov (United States)

    Roussel, P; Pérez, O; Labbé, P

    2001-10-01

    Phosphate tungsten bronzes have been shown to be conductors of low dimensionality. A review of the crystallographic and structural properties of this huge series of compounds is given here, corresponding to the present knowledge of the different X-ray studies and electron microscopy investigations. Three main families are described, monophosphate tungsten bronzes, Ax(PO2)4(WO3)2m, either with pentagonal tunnels (MPTBp) or with hexagonal tunnels (MPTBh), and diphosphate tungsten bronzes, Ax(P2O4)2(WO3)2m, mainly with hexagonal tunnels (DPTBh). The general aspect of these crystal structures may be described as a building of polyhedra sharing oxygen corners made of regular stacking of WO3-type slabs with a thickness function of m, joined by slices of tetrahedral PO4 phosphate or P2O7 diphosphate groups. The relations of the different slabs with respect to the basic perovskite structure are mentioned. The structural description is focused on the tilt phenomenon of the WO6 octahedra inside a slab of WO3-type. In this respect, a comparison with the different phases of the WO3 crystal structures is established. The various modes of tilting and the different possible connections between two adjacent WO3-type slabs involve a great variety of structures with different symmetries, as well as the existence of numerous twins in MPTBp's. Several phase transitions, with the appearance of diffuse scattering and modulation phenomena, were analysed by X-ray scattering measurements and through the temperature dependence of various physical properties for the MPTBp's. The role of the W displacements within the WO3-type slabs, in two modulated structures (m = 4 and m = 10), already solved, is discussed. Finally, the complexity of the structural aspects of DPTBh's is explained on the basis of the average structures which are the only ones solved.

  20. Identifying unknown nanocrystals by fringe fingerprinting in two dimensions and free-access crystallographic databases

    Science.gov (United States)

    Moeck, Peter; Čertik, Ondřej; Seipel, Bjoern; Groebner, Rebecca; Noice, Lori; Upreti, Girish; Fraundorf, Philip; Erni, Rolf; Browning, Nigel D.; Kiesow, Andreas; Jolivet, Jean-Pierre

    2005-11-01

    New needs to determine the crystallography of nanocrystals arise with the advent of science and engineering on the nanometer scale. Direct space high-resolution phase-contrast transmission electron microscopy (HRTEM) and atomic resolution Z-contrast scanning TEM (Z-STEM), when combined with tools for image-based nanocrystallography possess the capacity to meet these needs. This paper introduces such a tool, i.e. fringe fingerprinting in two dimensions (2D), for the identification of unknown nanocrystal phases and compares this method briefly to qualitative standard powder X-ray diffractometry (i.e. spatial frequency fingerprinting). Free-access crystallographic databases are also discussed because the whole fingerprinting concept is only viable if there are comprehensive databases to support the identification of an unknown nanocrystal phase. This discussion provides the rationale for our ongoing development of a dedicated free-access Nano-Crystallography Database (NCD) that contains comprehensive information on both nanocrystal structures and morphologies. The current status of the NCD project and plans for its future developments are briefly outlined. Although feasible in contemporary HRTEMs and Z-STEMs, fringe fingerprinting in 2D (and image-based nanocrystallography in general) will become much more viable with the increased availability of aberration-corrected transmission electron microscopes. When the image acquisition and interpretation are, in addition, automated in such microscopes, fringe fingerprinting in 2D will be able to compete with powder X-ray diffraction for the identification of unknown nanocrystal phases on a routine basis. Since it possesses a range of advantages over powder X-ray diffractometry, e.g., fringe fingerprint plots contain much more information for the identification of an unknown crystal phase, fringe fingerprinting in 2D may then capture a significant part of the nanocrystal metrology market.

  1. Crystallographic texture and microstructural changes in fusion welds of recrystallized Zry-4 rolled plates

    Science.gov (United States)

    Moya Riffo, A.; Vicente Alvarez, M. A.; Santisteban, J. R.; Vizcaino, P.; Limandri, S.; Daymond, M. R.; Kerr, D.; Okasinski, J.; Almer, J.; Vogel, S. C.

    2017-05-01

    This work presents a detailed characterization of the microstructural and crystallographic texture changes observed in the transition region in a weld between two Zircaloy-4 cold rolled and recrystallized plates. The microstructural study was performed by optical microscopy under polarized light and scanning electron microscopy (SEM). Texture changes were characterized at different lengthscales: in the micrometric size, orientation imaging maps (OIM) were constructed by electron backscatter diffraction (EBSD), in the millimetre scale, high energy XRD experiments were done at the Advanced Photon Source (USA) and compared to neutron diffraction texture determinations performed in the HIPPO instrument at Los Alamos National Laboratory. In the heat affected zone (HAZ) we observed the development of Widmanstätten microstructures, typical of the α(hcp) to β(bcc) phase transformation. Associated with these changes a rotation of the c-poles is found in the HAZ and fusion zone. While the base material shows the typical texture of a cold rolled plate, with their c-poles pointing 35° apart from the normal direction of the plate in the normal-transversal line, in the HAZ, c-poles align along the transversal direction of the plate and then re-orient along different directions, all of these changes occurring within a lengthscale in the order of mm. The evolution of texture in this narrow region was captured by both OIM and XRD, and is consistent with previous measurements done by Neutron Diffraction in the HIPPO diffractometer at Los Alamos National Laboratory, USA. The microstructural and texture changes along the HAZ were interpreted as arising due to the effect of differences in the cooling rate and β grain size on the progress of the different α variants during transformation. Fast cooling rates and large β grains are associated to weak variant selection during the β->α transformation, while slow cooling rates and fine β grains result in strong variant selection.

  2. Identification of succinic semialdehyde reductases from Geobacter: expression,purification, crystallization, preliminary functional, and crystallographic analysis

    Institute of Scientific and Technical Information of China (English)

    Yanfeng Zhang; Xiaoli Gao; Yi Zheng; R. Michae; Garavito

    2011-01-01

    Succinic semialdehyde reductase (SSAR) is an important enzyme involved in γ-aminobutyrate (GABA) metabolism.By converting succinic semialdehyde (SSA) to γ-hydroxybutyrate (GHB),the SSAR facilitates an alternative pathway for GABA degradation.In this study,we identified SSARs from Geobacter sulfurreducens and Geobacter metallireducens (GsSSAR and GmSSAR,respectively).The enzymes were over-expressed in Escherichia coil and purified to near homogeneity.Both GsSSAR and GmSSAR showed the activity of reducing SSA using nicotinamide adenine dinucleotide phosphate as a co-factor.The oligomeric sizes of GsSSAR and GmSSAR,as determined by analytical size exclusion chromatography,suggest that the enzymes presumably exist as tetramers in solution.The recombinant GsSSAR and GmSSAR crystallized in the presence of NADP+,and the resulting crystals diffracted to 1.89 (A) (GsSSAR) and 2.25 (A)(GmSSAR) resolution.The GsSSAR and GmSSAR crystals belong to the space groups P21221 (a =99.61 (A),b =147.49 (A),c =182.47 A) and P1 (a =75.97 (A) b =79.14 (A) c =95.47 (A),α =82.15°,β =88.80°,γ=87.66°),respectively.Preliminary crystallographic data analysis suggests the presence of eight protein monomers in the asymmetric units for both GsSSAR and GmSSAR.

  3. High-temperature in situ crystallographic observation of reversible gas sorption in impermeable organic cages.

    Science.gov (United States)

    Baek, Seung Bin; Moon, Dohyun; Graf, Robert; Cho, Woo Jong; Park, Sung Woo; Yoon, Tae-Ung; Cho, Seung Joo; Hwang, In-Chul; Bae, Youn-Sang; Spiess, Hans W; Lee, Hee Cheon; Kim, Kwang S

    2015-11-17

    Crystallographic observation of adsorbed gas molecules is a highly difficult task due to their rapid motion. Here, we report the in situ single-crystal and synchrotron powder X-ray observations of reversible CO2 sorption processes in an apparently nonporous organic crystal under varying pressures at high temperatures. The host material is formed by hydrogen bond network between 1,3,5-tris-(4-carboxyphenyl)benzene (H3BTB) and N,N-dimethylformamide (DMF) and by π-π stacking between the H3BTB moieties. The material can be viewed as a well-ordered array of cages, which are tight packed with each other so that the cages are inaccessible from outside. Thus, the host is practically nonporous. Despite the absence of permanent pathways connecting the empty cages, they are permeable to CO2 at high temperatures due to thermally activated molecular gating, and the weakly confined CO2 molecules in the cages allow direct detection by in situ single-crystal X-ray diffraction at 323 K. Variable-temperature in situ synchrotron powder X-ray diffraction studies also show that the CO2 sorption is reversible and driven by temperature increase. Solid-state magic angle spinning NMR defines the interactions of CO2 with the organic framework and dynamic motion of CO2 in cages. The reversible sorption is attributed to the dynamic motion of the DMF molecules combined with the axial motions/angular fluctuations of CO2 (a series of transient opening/closing of compartments enabling CO2 molecule passage), as revealed from NMR and simulations. This temperature-driven transient molecular gating can store gaseous molecules in ordered arrays toward unique collective properties and release them for ready use.

  4. Identification of succinic semialdehyde reductases from Geobacter: expression, purification, crystallization, preliminary functional, and crystallographic analysis

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yanfeng; Gao, Xiaoli; Zheng, Yi; Garavito, R. Michael (MSU)

    2012-04-30

    Succinic semialdehyde reductase (SSAR) is an important enzyme involved in {gamma}-aminobutyrate (GABA) metabolism. By converting succinic semialdehyde (SSA) to {gamma}-hydroxybutyrate (GHB), the SSAR facilitates an alternative pathway for GABA degradation. In this study, we identified SSARs from Geobacter sulfurreducens and Geobacter metallireducens (GsSSAR and GmSSAR, respectively). The enzymes were over-expressed in Escherichia coli and purified to near homogeneity. Both GsSSAR and GmSSAR showed the activity of reducing SSA using nicotinamide adenine dinucleotide phosphate as a co-factor. The oligomeric sizes of GsSSAR and GmSSAR, as determined by analytical size exclusion chromatography, suggest that the enzymes presumably exist as tetramers in solution. The recombinant GsSSAR and GmSSAR crystallized in the presence of NADP{sup +}, and the resulting crystals diffracted to 1.89 {angstrom} (GsSSAR) and 2.25 {angstrom} (GmSSAR) resolution. The GsSSAR and GmSSAR crystals belong to the space groups P2{sub 1}22{sub 1} (a = 99.61 {angstrom}, b = 147.49 {angstrom}, c = 182.47 {angstrom}) and P1 (a = 75.97 {angstrom}, b = 79.14 {angstrom}, c = 95.47 {angstrom}, {alpha} = 82.15{sup o}, {beta} = 88.80{sup o}, {gamma} = 87.66{sup o}), respectively. Preliminary crystallographic data analysis suggests the presence of eight protein monomers in the asymmetric units for both GsSSAR and GmSSAR.

  5. Functional analysis of hyperthermophilic endocellulase from Pyrococcus horikoshii by crystallographic snapshots.

    Science.gov (United States)

    Kim, Han-Woo; Ishikawa, Kazuhiko

    2011-07-15

    A hyperthermophilic membrane-related β-1,4-endoglucanase (family 5, cellulase) of the archaeon Pyrococcus horikoshii was found to be capable of hydrolysing cellulose at high temperatures. The hyperthermophilic cellulase has promise for applications in biomass utilization. To clarify its detailed function, we determined the crystal structures of mutants of the enzyme in complex with either the substrate or product ligands. We were able to resolve different kinds of complex structures at 1.65-2.01 Å (1 Å=0.1 nm). The structural analysis of various mutant enzymes yielded a sequence of crystallographic snapshots, which could be used to explain the catalytic process of the enzyme. The substrate position is fixed by the alignment of one cellobiose unit between the two aromatic amino acid residues at subsites +1 and +2. During the enzyme reaction, the glucose structure of cellulose substrates is distorted at subsite -1, and the β-1,4-glucoside bond between glucose moieties is twisted between subsites -1 and +1. Subsite -2 specifically recognizes the glucose residue, but recognition by subsites +1 and +2 is loose during the enzyme reaction. This type of recognition is important for creation of the distorted boat form of the substrate at subsite -1. A rare enzyme-substrate complex was observed within the low-activity mutant Y299F, which suggested the existence of a trapped ligand structure before the formation by covalent bonding of the proposed intermediate structure. Analysis of the enzyme-substrate structure suggested that an incoming water molecule, essential for hydrolysis during the retention process, might be introduced to the cleavage position after the cellobiose product at subsites +1 and +2 was released from the active site.

  6. Crystallographic, microstructure and mechanical characteristics of dynamically processed IN718 superalloy

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, A.D., E-mail: ads.hpu@gmail.com [Department of Physics, Himachal Pradesh University, Shimla 171005 (India); Sharma, A.K. [Terminal Ballistics Research Laboratory, Chandigarh 160030 (India); Thakur, N. [Department of Physics, Himachal Pradesh University, Shimla 171005 (India)

    2014-06-01

    Highlights: • Measurement of detonation velocity and compaction of powder are achieved together. • A plastic explosive detonation results into dense compacts without grain-growth. • We have studied crystallographic, micromechanical and microstructural features. • The results show no segregation within the compacts. • Density (98%), microhardness (470 ± 3)H{sub v}, microstrain (0.3%), UTS (806 MPa) are obtained. - Abstract: Dynamic consolidation of IN718 superalloy powder without grain-growth and negligible density gradient is accomplished through explosively generated shock wave loading. The compaction of powder and measurement of detonation velocity are achieved successfully in a single-shot experiment by employing instrumented detonics. A plastic explosive having a detonation velocity of the order of 7.1 km/s in a direct proximity with superalloy powder is used for the consolidation process. The compacted specimens are examined for structural, microstructure and mechanical characteristics. X-ray diffraction (XRD) study suggests intact crystalline structure of the compacts. A small micro-strain (0.26%) is observed by using Williamson–Hall method. Wavelength dispersive spectroscopy indicates no segregation within the shock processed superalloy compacted specimens. The monoliths investigated for fractography by using field emission scanning electron microscopy (FE-SEM) show original dendritic structure accompanied by re-solidified molten regions across the interparticle boundaries. Depth-sensing indentations (at 1.96 N) on compacted specimens show excellent micro-hardness of the order of (470 ± 3)H{sub v}. Tensile and compressive strengths of the superalloy monolith are observed to be 806 and 822 MPa, respectively.

  7. Crystallographic texture and microstructural changes in fusion welds of recrystallized Zry-4 rolled plates

    Energy Technology Data Exchange (ETDEWEB)

    Riffo, A. Moya; Alvarez, M.A.Vicente; Santisteban, J R; Vizcaino, P; Limandri, S.; Daymond, M. R.; Kerr, D.; Vogel, S C; Almer, J.; Okasinski, J.

    2017-02-08

    This study presents a detailed characterization of the microstructural and crystallographic texture changes observed in the transition region in a weld between two Zircaloy-4 cold rolled and recrystallized plates. The microstructural study was performed by optical microscopy under polarized light and scanning electron microscopy (SEM). Texture changes were characterized at different lengthscales: in the micrometric size, orientation imaging maps (OIM) were constructed by electron backscatter diffraction (EBSD), in the millimetre scale, high energy XRD experiments were done at the Advanced Photon Source (USA) and compared to neutron diffraction texture determinations performed in the HIPPO instrument at Los Alamos National Laboratory. In the heat affected zone (HAZ) we observed the development of Widmanstätten microstructures, typical of the α(hcp) to β(bcc) phase transformation. Associated with these changes a rotation of the c-poles is found in the HAZ and fusion zone. While the base material shows the typical texture of a cold rolled plate, with their c-poles pointing 35° apart from the normal direction of the plate in the normal-transversal line, in the HAZ, c-poles align along the transversal direction of the plate and then re-orient along different directions, all of these changes occurring within a lengthscale in the order of mm. The evolution of texture in this narrow region was captured by both OIM and XRD, and is consistent with previous measurements done by Neutron Diffraction in the HIPPO diffractometer at Los Alamos National Laboratory, USA. The microstructural and texture changes along the HAZ were interpreted as arising due to the effect of differences in the cooling rate and β grain size on the progress of the different α variants during transformation. Fast cooling rates and large β grains are associated to weak variant selection during the β–>α transformation, while slow cooling rates and fine β grains result in strong

  8. Structure and function of proteins investigated by crystallographic and spectroscopic time-resolved methods

    Science.gov (United States)

    Purwar, Namrta

    Biomolecules play an essential role in performing the necessary functions for life. The goal of this thesis is to contribute to an understanding of how biological systems work on the molecular level. We used two biological systems, beef liver catalase (BLC) and photoactive yellow protein (PYP). BLC is a metalloprotein that protects living cells from the harmful effects of reactive oxygen species by converting H2O2 into water and oxygen. By binding nitric oxide (NO) to the catalase, a complex was generated that mimics the Cat-H2O2 adduct, a crucial intermediate in the reaction promoted by the catalase. The Cat-NO complex is obtained by using a convenient NO generator (1-(N,N-diethylamino)diazen-1-ium-1,2-diolate). Concentrations up to 100˜200 mM are reached by using a specially designed glass cavity. With this glass apparatus and DEANO, sufficient NO occupation is achieved and structure determination of the catalase with NO bound to the heme iron becomes possible. Structural changes upon NO binding are minute. NO has a slightly bent geometry with respect to the heme normal, which results in a substantial overlap of the NO orbitals with the iron-porphyrin molecular orbitals. From the structure of the iron-NO complex, conclusions on the electronic properties of the heme iron can be drawn that ultimately lead to an insight into the catalytic properties of this enzyme. Enzyme kinetics is affected by additional parameters such as temperature and pH. Additionally, in crystallography, the absorbed X-ray dose may impair protein function. To address the effect of these parameters, we performed time-resolved crystallographic experiments on a model system, PYP. By collecting multiple time-series on PYP at increasing X-ray dose levels, we determined a kinetic dose limit up to which kinetically meaningful X-ray data sets can be collected. From this, we conclude that comprehensive time-series spanning up to 12 orders of magnitude in time can be collected from a single PYP

  9. The Independence of Jane Eyre

    Institute of Scientific and Technical Information of China (English)

    董引娣

    2015-01-01

    <正>Ⅰ.General Review of Jane Eyre’s Independence Jane’s independence also has something to do with dignity.Every time she was teased by her cousin,she would resist rather than keep silent.Even when she stayed with the so-called upperclass people,she behaved without any self-humiliation.Jane’s sufferings that give rise to her independence and unconquerable spirit to stay with Rochester,Jane didn’t feel herself inferior

  10. Nuclear, uranium, reserves, sustainability, independence; Nucleaire, Uranium, reserves, durabilite, independance

    Energy Technology Data Exchange (ETDEWEB)

    Acket, C

    2007-06-15

    In order to evaluate the energy independence concerning the nuclear energy, the author takes the state of the art about the uranium. He details the fuel needs, the reserves on the base of the today available techniques, the reserves on the base of the future techniques and concludes positively on the energy independence for the nuclear. (A.L.B.)

  11. Marketing Handbook for Independent Schools.

    Science.gov (United States)

    Boarding Schools, Boston, MA.

    This publication is a resource to help independent schools attract more familites to their institutions and to increase the voluntary support by the larger community surrounding the school. The first chapter attempts to dispel misconceptions, define pertinent marketing terms, and relate their importance to independent schools. The rest of the book…

  12. Central bank independence and ageing

    OpenAIRE

    Farvaque, Etienne; Héricourt, Jérôme; Lagadec, Gaël

    2008-01-01

    We contrast the influence of demography and central bank independence on inflation. The recent demographic trends in developed countries are shown to weight more on inflation than central bank independence, while the contrary stands for the period from 1960 to 1979.

  13. Crystallographic and magnetic properties of Cu{sub 2}U-type hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Kamishima, K., E-mail: kamisima@fms.saitama-u.ac.jp [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Saitama 338-8570 (Japan); Tajima, R.; Watanabe, K.; Kakizaki, K.; Fujimori, A.; Sakai, M. [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Saitama 338-8570 (Japan); Watanabe, K. [Global Research Cluster, Collaboration Promotion Unit, RIKEN, 2-1 Wako, Saitama 351-0198 (Japan); Abe, H. [Advanced Electronic Materials Center, National Institute of Materials Science, 1-1 Namiki, Tsukuba 305-0044 (Japan)

    2015-02-01

    We have investigated the synthesis conditions, and the magnetic properties of the Cu{sub 2}U-type hexagonal ferrite, Ba{sub 4}Cu{sub 2}Fe{sub 36}O{sub 60}. The Cu{sub 2}U-type hexaferrite was synthesized at the sintering temperature of 1050 °C with the initial composition of Ba{sub 4.4}Cu{sub 2}Fe{sub 37.6}O{sub 62.8} (Cu{sub 2}U+0.2T-block). The saturation magnetizations at 300 K and 5 K are 46.8 A m{sup 2}/kg and 65.0 A m{sup 2}/kg, respectively. The Curie temperature is 420 °C which is lower than that of the M-type ferrite (450 °C) but higher than that of the Cu{sub 2}Y-type ferrite (320 °C). The amount of the nonmagnetic impurity in this sample is estimated to be about 10 wt% by the electron probe micro analysis. We estimated the expected saturation magnetization to be 65.2 A m{sup 2}/kg, by assuming the model of a Néel-type ferrimagnetic structure and the reduction of magnetization by the 10 wt% nonmagnetic impurity. This is consistent with the observed magnetization of 65.0 A m{sup 2}/kg at 5 K. - Highlights: • We have synthesized the crystallographic single-phase Cu{sub 2}U-type hexagonal ferrite. • M{sub S} is found to be 46.8 A·m{sup 2}/kg at 300 K and 65.0 A·m{sup 2}/kg at 5 K. • T{sub C} is 420°C. It is lower than T{sub C}{sup M-type} (450°C) but higher than T{sub C}{sup Cu2Y-type} (320°C). • The estimated saturation magnetization is consistent with experimental M{sub S} at 5 K.

  14. Crystallographic Characteristic of Intermetallic Compounds in Al-Si-Mg Casting Alloys Using Electron Backscatter Diffraction

    Institute of Scientific and Technical Information of China (English)

    ZOU Yongzhi; XU Zhengbing; HE Juan; ZENG Jianmin

    2010-01-01

    The Al-Si-Mg alloy which can be strengthened by heat treatment is widely applied to the key components of aerospace and aeronautics. Iron-rich intermetallic compounds are well known to be strongly influential on mechanical properties in Al-Si-Mg alloys. But intermetallic compounds in cast Al-Si-Mg alloy intermetallics are often misidentified in previous metallurgical studies. It was described as many different compounds, such as AlFeSi, Al8Fe2Si, Al5(Fe, Mn)3Si2 and so on. For the purpose of solving this problem, the intermetallic compounds in cast Al-Si alloys containing 0.5% Mg were investigated in this study. The iron-rich compounds in Al-Si-Mg casting alloys were characterized by optical microscope(OM), scanning electron microscope(SEM), energy dispersive X-ray spectrometer(EDS), electron backscatter diffraction(EBSD) and X-ray powder diffraction(XRD). The electron backscatter diffraction patterns were used to assess the crystallographic characteristics of intermetallic compounds. The compound which contains Fe/Mg-rich particles with coarse morphologies was Al8FeMg3Si6 in the alloy by using EBSD. The compound belongs to hexagonal system, space group P2m, with the lattice parameter a=0.662 nm, c=0.792 nm. The β-phase is indexed as tetragonal Al3FeSi2, space group I4/mcm, a=0.607 nm and c=0.950 nm. The XRD data indicate that Al8FeMg3Si6 and Al3FeSi2 are present in the microstructure of Al-7Si-Mg alloy, which confirms the identification result of EBSD. The present study identified the iron-rich compound in Al-Si-Mg alloy, which provides a reliable method to identify the intermetallic compounds in short time in Al-Si-Mg alloy. Study results are helpful for identification of complex compounds in alloys.

  15. Hematite and Goethite (U-Th)/He/Ne ages interpretation using crystallographic data and diffusion parameters

    Science.gov (United States)

    Gautheron, Cécile; Balout, Hilal; Roques, Jérôme; Allard, Thierry; Morin, Guillaume; Tassan-Got, Laurent

    2016-04-01

    incorporated in this code in order to reproduce realistic crystallographic structure. Balout, H., Roques, J., Gautheron, C., Tassan-Got, L., Mbongo-Djimbi, D., submitted a. Helium diffusion in pure hematite (α-Fe2O3) for thermochronometric applications: a theoretical multi-scale study. Balout, H., Roques, J., Gautheron, C., Tassan-Got, L., submitted b. Computational investigation of the interstitial neon diffusion in pure hematite, α-Fe2O3. Gautheron, C., Tassan-Got, L., 2010. A Monte Carlo approach of diffusion applied to noble gas/helium thermochronology. Chemical Geology, 273: 212-224.

  16. In situ monitoring of crystallographic changes in Pd induced by diffusion of D

    Science.gov (United States)

    Skelton, E. F.; Hagans, P. L.; Qadri, S. B.; Dominguez, D. D.; Ehrlich, A. C.; Hu, J. Z.

    1998-12-01

    Crystallographic changes in a palladium wire cathode were monitored in situ, as deuterium was electrochemically deposited on the surface and diffused radially into the wire. Initially, the wire was pure Pd. A constant electrolysis current density of 1 mA/cm2 was maintained and D slowly diffused into the wire. As the D concentration increased, the wire transformed from pure Pd, to the α phase, and finally into the β phase. This reversible phase transformation begins on the surface and progresses radially inward. During the experiment, x-ray-diffraction data were collected from a volume element of about 180 pl. This volume element was systematically moved in 50-μm steps from the edge to the center of a 1.0 mm diameter Pd wire. Throughout the course of the experiment, the bulk value of x in PdDx, as determined from simultaneous measurements of the electrical resistivity, increased from 0 to ~0.72. For each setting of the volume element, a monotonic increase in the volume of the α phase was observed, until the material entered the two-phase region. Once the β phase appeared, the volumes of both phases decreased slightly with continued loading. The integrated intensities of diffraction peaks from each phase were used in conjunction with the known phase diagram to estimate the rate of compositional change within the volume element. The diffusion rate for the solute atoms was estimated to be 57+/-8 nm/s, based on the temporal and spatial dependence of the integrated intensities of the diffraction peaks from each phase. These data also were used to evaluate the time dependence of the concentration of the solute atoms ∂c/∂t and their diffusivity D. The value of ∂c/∂t increased linearly from 6.2×10-5 s-1 at the surface, to 7.6×10-5 s-1 midway into the wire. D was computed to be (3.1+/-1.0)×10-11 m2/s when the transition began at r=250 μm 2 ks later it had decreased to (2.1+/-0.3)×10-11 m2/s. This may be due to the fact that the volume of the β lattice also

  17. Local dynamics of proteins and DNA evaluated from crystallographic B factors

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Bohdan, E-mail: bohdan.schneider@gmail.com [Institute of Biotechnology AS CR, Videnska 1083, 142 20 Prague (Czech Republic); Gelly, Jean-Christophe; Brevern, Alexandre G. de [INSERM, U1134, DSIMB, 75739 Paris (France); Université Paris Diderot, Sorbonne Paris Cité, UMR-S 1134, 75739 Paris (France); Institut National de la Transfusion Sanguine (INTS), 75739 Paris (France); Laboratoire d’Excellence GR-Ex, 75739 Paris (France); Černý, Jiří [Institute of Biotechnology AS CR, Videnska 1083, 142 20 Prague (Czech Republic)

    2014-09-01

    surprising. The features discriminating different types of residues are less pronounced in structures with lower crystallographic resolution. Some of the observed trends are likely to be the consequence of improper refinement protocols that may need to be rectified.

  18. Mineralogical, crystallographic and redox features of the earliest stages of fluid alteration in CM chondrites

    Science.gov (United States)

    Pignatelli, Isabella; Marrocchi, Yves; Mugnaioli, Enrico; Bourdelle, Franck; Gounelle, Matthieu

    2017-07-01

    The CM chondrites represent the largest group of hydrated meteorites and span a wide range of conditions, from less altered (i.e., CM2) down to heavily altered (i.e., CM1). The Paris chondrite is considered the least altered CM and thus enables the earliest stages of aqueous alteration processes to be deciphered. Here, we report results from a nanoscale study of tochilinite/cronstedtite intergrowths (TCIs) in Paris-TCIs being the emblematic secondary mineral assemblages of CM chondrites, formed from the alteration of Fe-Ni metal beads (type-I TCIs) and anhydrous silicates (type-II TCIs). We combined high-resolution transmission electron microscopy, scanning transmission X-ray microscopy and electron diffraction tomography to characterize the crystal structure, crystal chemistry and redox state of TCIs. The data obtained are useful to reconstruct the alteration conditions of Paris and to compare them with those of other meteorites. Our results show that tochilinite in Paris is characterized by a high hydroxide layer content (n = 2.1-2.2) regardless of the silicate precursors. When examined alongside other CMs, it appears that the hydroxide layer and iron contents of tochilinites correlate with the degree of alteration experienced by the chondrites. The Fe3+/ΣFe ratios of TCIs are high: 8-15% in tochilinite, 33-60% in cronstedtite and 70-80% in hydroxides. These observations suggest that alteration of CM chondrites took place under oxidizing conditions that could have been induced by significant H2 release during serpentinization. Similar results were recently reported in CR chondrites (Le Guillou et al., 2015), suggesting that the process(es) controlling the redox state of the secondary mineral assemblages were quite similar in the CM and CR parent bodies despite the different alteration conditions. According to our mineralogical and crystallographic survey, the formation of TCIs in Paris occurred at temperatures lower than 100 °C, under neutral, slightly alkaline

  19. Crystallographically Oriented Cobalt Chromium Tantalum Thin-Film Media for High Areal Density Recording.

    Science.gov (United States)

    Deng, Youping

    In order to develop the techniques for increasing recording areal density, microstructural, magnetic and recording properties of crystallographically-oriented CoCrTa thin-films were investigated. The oriented films included bi-crystal and quad-crystal CoCrTa thin films, which were prepared by sputtering on (100) and (110) single crystal Cr substrates, respectively. A theoretical model was developed to calculate the in-plane torque curves of the oriented films. Based on this model, experimental investigations were conducted on the quad-crystal CoCrTa films. It was found that, by fitting the measured in-plane torque curves of the quad -crystal CoCrTa film, it was possible to determine the magnetocrystalline anisotropy constants (K_{rm u1 } and K_{rm u2}) of the CoCrTa film. The torque curves of quad -crystal films were also found to be indicative of the grain isolation and could be used to optimize the sputtering conditions. Substrate bias changed the film composition and lowered M_{rm s} and K_{rm u1}, while improving grain isolation. A more realistic micromagnetic model, which used the measured values of M_ {rm s} and K_{ rm u1} and took the film's grain-cluster microstructure into account, was developed for the bi-crystal films. The simulation results fitted well with the experimental data. A low-speed contact-recording spin-stand, which utilized a magnetoresistive head, was set up for recording studies on the oriented thin-film media and an isotropic thin-film medium prepared on a NiP/Al substrate. The readback signal from the MR head appeared to have some correlation with the medium anisotropy. The recorded patterns were imaged by magnetic force microscopy. It was found that erased bands formed on the quad-crystal and isotropic thin -film media. On the bi-crystal thin-film media, however, clear erased bands were not observed possibly due to the large head-disk distance.

  20. [μ-2,3,5,6-Tetra-kis(2-pyrid-yl)pyrazine-κN,N,N:N,N,N]bis-[diaqua(dihydrogen m-phenylene-diphospho-nato-κO)nickel(II)] dihydrate.

    Science.gov (United States)

    Deburgomaster, Paul; Zubieta, Jon

    2010-10-23

    The title compound [Ni(2)(C(6)H(6)O(6)P(2))(2)(C(24)H(16)N(6))(H(2)O)(4)]·2H(2)O or [Ni(2)(tpyprz)(1,3-HO(3)PC(6)H(4)PO(3)H)(2)(H(2)O)(4)]·2H(2)O [tpyprz = tetra-kis-(2-pyrid-yl)pyrazine, C(24)H(16)N(6)] is a binuclear complex with a crystallographic inversion center located at the center of the pyrazine ring. The equivalent nickel(II) sites exhibit a distorted {NiO(3)N(3)} octa-hedral coordination, with the three nitro-gen donors of each terminus of the tpyprz ligand in a meridional orientation. An aqua ligand occupies the position trans to the pyrazine nitro-gen donor, while the second aqua ligand is trans to the oxygen donor of the dihydrogen-1,3-phenyl-diphospho-nate ligand. The Ni-O and Ni-N bond lengths fall in the range 2.011 (3) to 2.089 (3) Å. The protonation sites on the organo-phospho-nate ligand are evident in the significantly longer P-O bonds compared to the unprotonated sites. In the crystal structure, the complex mol-ecules and the solvent water mol-ecules are linked into a three-dimensional hydrogen-bonded framework through O-H⋯O inter-actions between the aqua ligands, the protonated organo-phospho-nate oxygen atoms and the water mol-ecules of crystallization. Intra-molecular π-stacking between the phenyl group of the phospho-nate ligand and a pyridyl group of the tpyprz ligand, at a distance of 3.244 (5) Å between ring centroids, is also observed.

  1. Dissolution of quartz in aqueous basic solution, 106-236 C - Surface kinetics of 'perfect' crystallographic faces

    Science.gov (United States)

    Gratz, Andrew J.; Bird, Peter; Quiro, Glenn B.

    1990-01-01

    A highly accurate method, called the negative crystal method, for determining the rate of dissolution on specific crystallographic faces of crystals was developed, in which the dissolution rates of nominally perfect crystal faces are obtained by measuring the size of individual negative crystals during a sequence of dissolution steps. The method was applied to determine the apparent activation energy and rate constants for the dissolution of quartz in 0.01 M KOH solutions at temperatures from 106 to 236 C. Also investigated were the effects of hydroxyl activity and ionic strength. The apparent activation energies for the dissolution of the prism and of the rhomb were determined.

  2. phenix.model_vs_data: a high-level tool for the calculation of crystallographic model and data statistics.

    Science.gov (United States)

    Afonine, Pavel V; Grosse-Kunstleve, Ralf W; Chen, Vincent B; Headd, Jeffrey J; Moriarty, Nigel W; Richardson, Jane S; Richardson, David C; Urzhumtsev, Alexandre; Zwart, Peter H; Adams, Paul D

    2010-08-01

    phenix.model_vs_data is a high-level command-line tool for the computation of crystallographic model and data statistics, and the evaluation of the fit of the model to data. Analysis of all Protein Data Bank structures that have experimental data available shows that in most cases the reported statistics, in particular R factors, can be reproduced within a few percentage points. However, there are a number of outliers where the recomputed R values are significantly different from those originally reported. The reasons for these discrepancies are discussed.

  3. Crystallization and preliminary crystallographic studies of a cysteine protease inhibitor from the human nematode parasite Ascaris lumbricoides.

    Science.gov (United States)

    Liu, Sanling; Dong, Jianmei; Mei, Guoqiang; Liu, Guiyun; Xu, Wei; Su, Zhong; Liu, Jinsong

    2011-02-01

    The cysteine protease inhibitor from Ascaris lumbricoides, a roundworm that lives in the human intestine, may be involved in the suppression of human immune responses. Here, the molecular cloning, protein expression and purification, preliminary crystallization and crystallographic characterization of the cysteine protease inhibitor from A. lumbricoides are reported. The rod-shaped crystal belonged to space group C2, with unit-cell parameters a = 99.40, b = 37.52, c = 62.92 Å, β = 118.26°. The crystal diffracted to 2.1 Å resolution and contained two molecules in the asymmetric unit.

  4. Crystallographic analysis of the solid-state dewetting of polycrystalline gold film using automated indexing in a transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Jang, S. A.; Lee, H. J.; Oh, Y. J., E-mail: yjoh@hanbat.ac.kr [Department of Advanced Materials Science and Engineering, Hanbat National University, 125, Dongseo-daero, Yuseong-gu, Daejeon 305-719 (Korea, Republic of); Thompson, C. V.; Ross, C. A., E-mail: caross@mit.edu [Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-12-01

    We analyzed the effect of crystallographic anisotropy on the morphological evolution of a 12-nm-thick gold film during solid-state dewetting at high temperatures using automated indexing tool in a transmission electron microscopy. Dewetting initiated at grain-boundary triple junctions adjacent to large grains resulting from abnormal grain growth driven by (111) texture development. Voids at the junctions developed shapes with faceted edges bounded by low-index crystal planes. The kinetic mobility of the edges varied with the crystal orientation normal to the edges, with a predominance of specific edges with the slowest retraction rates as the annealing time was increased.

  5. Novel GaN-based vertical heterostructure field effect transistor structures using crystallographic KOH etching and overgrowth

    Science.gov (United States)

    Qian, H.; Lee, K. B.; Vajargah, S. Hosseini; Novikov, S. V.; Guiney, I.; Zaidi, Z. H.; Jiang, S.; Wallis, D. J.; Foxon, C. T.; Humphreys, C. J.; Houston, P. A.

    2017-02-01

    A novel V-groove vertical heterostructure field effect transistor structure is proposed using semi-polar (11-22) GaN. A crystallographic potassium hydroxide self-limiting wet etching technique was developed to enable a damage-free V-groove etching process. An AlGaN/GaN HFET structure was successfully regrown by molecular beam epitaxy on the V-groove surface. A smooth AlGaN/GaN interface was achieved which is an essential requirement for the formation of a high mobility channel.

  6. Crystallographic information of intermediate phases in binary Mg–X (X=Sn, Y, Sc, Ag alloys

    Directory of Open Access Journals (Sweden)

    Dongyan Liu

    2015-09-01

    Full Text Available The compositions and structures of thermodynamically stable or metastable precipitations in binary Mg-X (X=Sn, Y, Sc, Ag alloys are predicted using ab-initio evolutionary algorithm. The geometry optimizations of the predicted intermetallic compounds are carried out in the framework of density functional theory (DFT [1]. A complete list of the optimized crystallographic information (in cif format of the predicted intermetallic phases is presented here. The data is related to “Predictions on the compositions, structures, and mechanical properties of intermediate phases in binary Mg–X (X=Sn, Y, Sc, Ag alloys” by Liu et al. [2].

  7. Independent Innovation Is a Must

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The importance of independent innovation has been recognized by the Chinese Government and the public. The 11 th Five-Year Plan (2006-10) sets the enhancement of China's capability of independent innovation and the creation of an innovation-driven growth mode as the national strategy that is required to be integrated into every aspect of society. "Independent innovation" was also a key word in Premier Wen Jiabao's report on government work at the recent session of the National People's Congress, the top ...

  8. Independent EEG sources are dipolar

    National Research Council Canada - National Science Library

    Delorme, Arnaud; Palmer, Jason; Onton, Julie; Oostenveld, Robert; Makeig, Scott

    2012-01-01

    Independent component analysis (ICA) and blind source separation (BSS) methods are increasingly used to separate individual brain and non-brain source signals mixed by volume conduction in electroencephalographic (EEG...

  9. Logical independence and quantum randomness

    Energy Technology Data Exchange (ETDEWEB)

    Paterek, T; Kofler, J; Aspelmeyer, M; Zeilinger, A; Brukner, C [Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, A-1090 Vienna (Austria); Prevedel, R; Klimek, P [Faculty of Physics, University of Vienna, Boltzmanngasse 5, A-1090 Vienna (Austria)], E-mail: tomasz.paterek@univie.ac.at

    2010-01-15

    We propose a link between logical independence and quantum physics. We demonstrate that quantum systems in the eigenstates of Pauli group operators are capable of encoding mathematical axioms and show that Pauli group quantum measurements are capable of revealing whether or not a given proposition is logically dependent on the axiomatic system. Whenever a mathematical proposition is logically independent of the axioms encoded in the measured state, the measurement associated with the proposition gives random outcomes. This allows for an experimental test of logical independence. Conversely, it also allows for an explanation of the probabilities of random outcomes observed in Pauli group measurements from logical independence without invoking quantum theory. The axiomatic systems we study can be completed and are therefore not subject to Goedel's incompleteness theorem.

  10. Provisional coverage for independent workers

    OpenAIRE

    Díaz, Luis Eduardo

    2010-01-01

    The study examines how, from the traditional work of the independent artisan, we have moved to autonomous work integrated within networks of specialized businesses. This modality is owed not only to the manner in which labor is organized today, to government stimuli, to actions of multilaterals, but also to unemployment. With the purpose of humanizing independent work and rationalizing business costs, an intermediate category of autonomous worker has been created; the semi-dependent who...

  11. Crystallographic Analysis of Martensite in 0.2C-2.0Mn-1.5Si-0.6Cr Steel using EBSD

    Institute of Scientific and Technical Information of China (English)

    Pasi P. Suikkanen; Cyril Cayron; Anthony J. DeArdo; L Pentti Karjalainen

    2011-01-01

    The crystallography of martensite formed in 0.2C-2.0Mn-1,5Si-0.6Cr steel was studied using the electron backscattered diffraction (EBSD) technique. The results showed that the observed orientation relationship (OR) was closer to that of Nishiyama-Wassermann (N-W) than Kurdjumov-Sachs. The martensite consisted of parallel laths forming morphological packets. Typically, there were three different lath orientations in a morphological packet consisting of three specific N-W OR variants sharing the same {111} austenite plane. A packet of martensite laths with a common {111} austenite plane was termed a crystallographic packet. Generally, the crystallographic packet size corresponded to the morphological packet size, but occasionally the morphological packet was found to consist of two or more crystallographic packets. Therefore, the crystallographic packet size appeared to be finer than the morphological packet size. The relative orientation between the variants in crystallographic packets was found to be near 60°〈110〉, which explains the strong peak observed near 60° in the grain boundary misorientation distribution. Martensite also contained a high fraction of boundaries with a misorientation in the range 2.5-8°. Typically these boundaries were found to be located inside the martensite laths forming sub-laths.

  12. Development of olivine crystallographic preferred orientation in response to strain-induced fabric geometry

    Science.gov (United States)

    Chatzaras, Vasileios; Kruckenberg, Seth C.; Cohen, Shaina M.; Medaris, L. Gordon, Jr.; Withers, Anthony C.; Bagley, Brian

    2016-04-01

    The effect of finite strain ellipsoid geometry on crystallographic preferred orientation (CPO) is well known for crustal minerals (e.g., quartz, calcite, biotite, and hornblende). In the upper mantle, however, it remains poorly constrained how strain and fabric may affect olivine CPO. We present data from a suite of 40 spinel peridotite xenoliths from Marie Byrd Land (west Antarctica), which support an interpretation that fabric geometry rather than deformation conditions control the development of olivine CPO. We use X-ray computed tomography (XRCT) to quantitatively determine spinel fabric (orientation and geometry). Olivine CPOs, determined by Electron Backscattered Diffraction (EBSD), are plotted with respect to the XRCT-derived spinel foliation and lineation; this approach allows for the accurate, and unbiased, identification of CPO symmetries and types in mantle xenoliths. The combined XRCT and EBSD data show that the xenoliths are characterized by a range of fabric geometries (from oblate to prolate) and olivine CPO patterns; we recognize the A-type, axial-[010], axial-[100], and B-type patterns. The mantle xenoliths equilibrated at temperatures 779-1198 oC, as determined by 2-Px geothermometry. Using a geotherm consistent with the stability of spinel in all xenoliths, the range of equilibration temperatures occurs at depths between 39 and 72 km. Olivine recrystallized grain size piezometry reveals differential stresses ranging 2-60 MPa. Analysis of low-angle misorientation axes show a wide range in the distribution of rotation axes, with dominant {0kl}[100] slip. We use Fourier Transform Infrared (FTIR) spectroscopy to estimate the water content in the xenolith with the B-type CPO pattern. FTIR analysis shows that the equilibrium H concentration in olivine is low (4-13 ppm H2O). Combining these data, we observe that olivine CPO symmetry is controlled neither by the deformation conditions (stress, temperature, pressure, water content) for the range of

  13. Chemical, crystallographic and stable isotopic properties of alunite and jarosite from acid-Hypersaline Australian lakes

    Science.gov (United States)

    Alpers, C.N.; Rye, R.O.; Nordstrom, D.K.; White, L.D.; King, B.-S.

    1992-01-01

    Chemical, crystallographic and isotopic analyses were made on samples containing alunite and jarosite from the sediments of four acid, hypersaline lakes in southeastern and southwestern Australia. The alunite and jarosite are K-rich with relatively low Na contents based on chemical analysis and determination of unit cell dimensions by powder X-ray diffraction. Correcting the chemical analyses of fine-grained mineral concentrates from Lake Tyrrell, Victoria, for the presence of halite, silica and poorly crystalline aluminosilicates, the following formulas indicate best estimates for solid-solution compositions: for alunite, K0.87Na0.04(H3O)0.09(Al 0.92Fe0.08)3(SO4)2(OH) 6 and for jarosite, K0.89Na0.07(H3O)0.04(Fe 0.80Al0.20)3(SO4)2(OH) 6. The ??D-values of alunite are notably larger than those for jarosite from Lake Tyrrell and it appears that the minerals have closely approached hydrogen isotope equilibrium with the acidic regional groundwaters. The ??D results are consistent with a fractionation ???60-70??? between alunite and jarosite observed in other areas. However, interpretation of ??D results is complicated by large variability in fluid ??DH2O from evaporation, mixing and possible ion hydration effects in the brine. ??D-values of water derived from jarosite by step-wise heating tend to be smaller at 250??C, at which temperature hydronium and other non-hydroxyl water is liberated, than at 550??C, where water is derived from the hydroxyl site, but the differences are not sufficiently different to invalidate measurements of total ??D obtained by conventional, single-step heating methods. ??34S-values for alunite and jarosite from the four lakes (+19.7 to +21.2??? CDT) and for aqueous sulfate from Lake Tyrrell (+18.3 to +19.8???) are close to the values for modern evaporites (+21.5 ??0.3???) and seawater (+20??0.5???) and are probably typical of seawater-derived aerosols in arid coastal environments. ??34-S-values slightly smaller than that for seawater may

  14. Development of (1 0 0) crystallographic texture in magnetostrictive Fe-Ga wires using a modified Taylor wire method

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, S P; Quigley, P E; Avery, K J [Defence R and D Canada-Atlantic, 9 Grove Street, Dartmouth, NS, B2Y 3Z7 (Canada); Hatchard, T D; Flynn, S E; Dunlap, R A, E-mail: shannonfarrell@drdc-rddc.gc.c [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, NS, B3H 3J5 (Canada)

    2009-07-07

    Magnetostrictive Fe-Ga wires 1-3 mm in diameter have been prepared using an innovative cost-effective approach-based on the Taylor wire method-that couples the advantages of high-temperature directional solidification and selective grain growth. Strict control of drawing processes has been shown to enable the introduction of desirable texture that is critical for achieving large magnetostriction in these polycrystalline Fe-Ga alloys. The procedure for fabricating highly textured (1 0 0) magnetostrictive wires is discussed and the wires are evaluated in terms of microstructure and crystallographic texture. Magnetostriction measurements, in the absence of pre-stress and stress-annealing treatments, indicated a maximum magnetostriction of approx170 ppm in a saturation field less than 60 mT. A mechanism for texture evolution is proposed. It is speculated that the resultant (1 0 0) texture of the Fe-Ga wires is due to directional solidification and abnormal grain growth resulting from surface effects. The unique properties of wires made with the Taylor-based approach coupled with the low fabrication cost make this an attractive approach for the production of Fe-Ga wire with a specific crystallographic texture.

  15. Independent Research and Independent Exploratory Development FY 1985

    Science.gov (United States)

    1986-01-01

    complexity and cerebral sensory interaction. Personality and Individual Differences , 6(2), 253-261. Federico, P-A (1985). Individual differences in concept...learning and brain event-related potentials. Personality and Individual Differences , 6(2), 243-252. INDEPENDENT EXPLORATORY DEVELOPMENT PUBLICATIONS

  16. Crystal structure of (2,11-di-aza-[3.3](2,6)pyridino-phane-κ (4) N,N',N'',N''')(1,6,7,12-tetra-aza-perylene-κ (2) N (1),N (12))ruthenium(II) bis-(hexa-fluorido-phosphate) aceto-nitrile 1.422-solvate.

    Science.gov (United States)

    Brietzke, Thomas; Rottke, Falko Otto; Kelling, Alexandra; Schilde, Uwe; Holdt, Hans-Jürgen

    2014-10-01

    In the title compound, [Ru(C14H16N4)(C16H8N4)](PF6)2·1.422CH3CN, discrete dimers of complex cations, [Ru(L-N4H2)tape](2+) are formed {L-N4H2 = 2,11-di-aza-[3.3](2,6)pyridino-phane; tape = 1,6,7,12-tetra-aza-perylene}, held together by π-π stacking inter-actions via the tape ligand moieties with a centroid-centroid distance of 3.49 (2) Å, assisted by hydrogen bonds between the non-coordinating tape ligand α,α'-di-imine unit and the amine proton of a 2,11-di-aza-[3.3](2,6)-pyridino-phane ligand of the opposite complex cation. The combination of these inter-actions leads to an unusual nearly face-to-face π-π stacking mode. Additional weak C-H⋯N, C-H⋯F, N-H⋯F and P-F⋯π-ring (tape, py) (with F⋯centroid distances of 2.925-3.984 Å) inter-actions are found, leading to a three-dimensional architecture. The Ru(II) atom is coordinated in a distorted octa-hedral geometry, particularly manifested by the Namine-Ru-Namine angle of 153.79 (10)°. The counter-charge is provided by two hexa-fluorido-phosphate anions and the asymmetric unit is completed by aceto-nitrile solvent mol-ecules of crystallization. Disorder was observed for both the hexa-fluorido-phosphate anions as well as the aceto-nitrile solvate mol-ecules, with occupancies for the major moieties of 0.801 (6) for one of the PF6 anions, and a shared occupancy of 0.9215 (17) for the second PF6 anion and a partially occupied aceto-nitrile mol-ecule. A second CH3CN mol-ecule is fully occupied, but 1:1 disordered across a crystallographic inversion center.

  17. Introduction to algebraic independence theory

    CERN Document Server

    Philippon, Patrice

    2001-01-01

    In the last five years there has been very significant progress in the development of transcendence theory. A new approach to the arithmetic properties of values of modular forms and theta-functions was found. The solution of the Mahler-Manin problem on values of modular function j(tau) and algebraic independence of numbers pi and e^(pi) are most impressive results of this breakthrough. The book presents these and other results on algebraic independence of numbers and further, a detailed exposition of methods created in last the 25 years, during which commutative algebra and algebraic geometry exerted strong catalytic influence on the development of the subject.

  18. Strong sequences and independent sets

    Directory of Open Access Journals (Sweden)

    Joanna Jureczko

    2016-05-01

    Full Text Available A family $\\mathcal{S} \\in \\mathcal{P}(\\omega$ is \\textit{an independent family} if for each pair $\\mathcal{A, B}$ of disjoint finite subsets of $\\mathcal{S}$ the set $\\bigcap \\mathcal{A} \\cap (\\omega \\setminus \\bigcup \\mathcal{B}$ is nonempty. The fact that there is an independent family on $\\omega$ of size continuum was proved by Fichtenholz and Kantorowicz in \\cite{FK}. If we substitute $\\mathcal{P}(\\omega$ by a set $(X, r$ with arbitrary relation \\textit{r} it is natural question about existence and length of an independent set on $(X, r$. In this paper special assumptions of such existence will be considered. On the other hand in 60s' of the last century the strong sequences method was introduced by Efimov. He used it for proving some famous theorems in dyadic spaces like: Marczewski theorem on cellularity, Shanin theorem on a calibre, Esenin-Volpin theorem and others. In this paper there will be considered: length of strong sequences, the length of independent sets and other well known cardinal invariants and there will be examined inequalities among them.

  19. Boston: Cradle of American Independence

    Science.gov (United States)

    Community College Journal, 2004

    2004-01-01

    The 2005 American Association of Community Colleges Annual Convention will be held April 6-9 in Boston. While thoroughly modern, the iconic city's identity is firmly rooted in the past. As the cradle of American independence, Boston's long history is an integral part of the American fabric. Adams, Revere, Hancock are more than historical figures;…

  20. Background Independent String Field Theory

    CERN Document Server

    Bars, Itzhak

    2014-01-01

    We develop a new background independent Moyal star formalism in bosonic open string field theory. The new star product is formulated in a half-phase-space, and because phase space is independent of any background fields, the interactions are background independent. In this basis there is a large amount of symmetry, including a supersymmetry OSp(d|2) that acts on matter and ghost degrees of freedom, and simplifies computations. The BRST operator that defines the quadratic kinetic term of string field theory may be regarded as the solution of the equation of motion A*A=0 of a purely cubic background independent string field theory. We find an infinite number of non-perturbative solutions to this equation, and are able to associate them to the BRST operator of conformal field theories on the worldsheet. Thus, the background emerges from a spontaneous-type breaking of a purely cubic highly symmetric theory. The form of the BRST field breaks the symmetry in a tractable way such that the symmetry continues to be us...

  1. Cobordism Independence of Grassmann Manifolds

    Indian Academy of Sciences (India)

    Ashish Kumar Das

    2004-02-01

    This note proves that, for $F=\\mathbb{R},\\mathbb{C}$ or $\\mathbb{H}$, the bordism classes of all non-bounding Grassmannian manifolds $G_k(F^{n+k})$, with < and having real dimension , constitute a linearly independent set in the unoriented bordism group $\\mathfrak{N}_d$ regarded as a $\\mathbb{Z}_2$-vector space.

  2. Testing bivariate independence and normality

    NARCIS (Netherlands)

    Kallenberg, W.C.M.; Ledwina, Teresa; Rafajlowicz, Ewaryst

    1997-01-01

    In many statistical studies the relationship between two random variables X and Y is investigated and in particular the question whether X and Y are independent and normally distributed is of interest. Smooth tests may be used for testing this. They consist of several components, the first measuring

  3. Purification, crystallization and preliminary crystallographic studies of a Kunitz-type proteinase inhibitor from tamarind (Tamarindus indica) seeds.

    Science.gov (United States)

    Patil, Dipak N; Chaudhry, Anshul; Sharma, Ashwani K; Tomar, Shailly; Kumar, Pravindra

    2009-07-01

    A Kunitz-type proteinase inhibitor has been purified from tamarind (Tamarindus indica) seeds. SDS-PAGE analysis of a purified sample showed a homogeneous band corresponding to a molecular weight of 21 kDa. The protein was identified as a Kunitz-type proteinase inhibitor based on N-terminal amino-acid sequence analysis. It was crystallized by the vapour-diffusion method using PEG 6000. The crystals belonged to the orthorhombic space group C222(1), with unit-cell parameters a = 37.2, b = 77.1, c = 129.1 A. Diffraction data were collected to a resolution of 2.7 A. Preliminary crystallographic analysis indicated the presence of one proteinase inhibitor molecule in the asymmetric unit, with a solvent content of 44%.

  4. Expression, purification and preliminary crystallographic analysis of a haem-utilizing protein, HutX, from Vibrio cholerae

    Science.gov (United States)

    Su, Tiantian; Chi, Kaikai; Wang, Kang; Guo, Liming; Huang, Yan

    2015-01-01

    Vibrio cholerae, the causative agent of cholera, has developed a variety of mechanisms to obtain the limited-availability iron from human hosts. One important method for iron acquisition is through haem-uptake systems. Although the transport of haem has been widely studied, the fate of haem once it enters the cytoplasm remains an open question. Here, preliminary X-ray crystallographic analysis was performed on HutX, a member of the conserved haem-utilization operon from V. cholerae strain N16961. The crystals of HutX were found to belong to the orthorhombic space group C2221, with unit-cell parameters a = 50.1, b = 169.0, c = 81.8 Å. There are two protein molecules in the asymmetric unit, with a corresponding Matthews coefficient V M of 2.06 Å3 Da−1 and a solvent content of 40.28%. PMID:25664785

  5. Coupling of bias-induced crystallographic shear planes with charged domain walls in ferroelectric oxide thin films

    Science.gov (United States)

    Han, Myung-Geun; Garlow, Joseph A.; Bugnet, Matthieu; Divilov, Simon; Marshall, Matthew S. J.; Wu, Lijun; Dawber, Matthew; Fernandez-Serra, Marivi; Botton, Gianluigi A.; Cheong, Sang-Wook; Walker, Frederick J.; Ahn, Charles H.; Zhu, Yimei

    2016-09-01

    Polar discontinuity at interfaces plays deterministic roles in charge transport, magnetism, and even superconductivity of functional oxides. To date, most polar discontinuity problems have been explored in heterointerfaces between two dissimilar materials. Here, we show that charged domain walls (CDWs) in epitaxial thin films of ferroelectric PbZ r0.2T i0.8O3 are strongly coupled to polar interfaces through the formation of 1/2 {h 0 l } - type crystallographic shear planes (CSPs). Using atomic resolution imaging and spectroscopy we illustrate that the CSPs consist of both conservative and nonconservative segments when coupled to the CDWs where necessary compensating charges for stabilizing the CDWs are associated with vacancies at the CSPs. The CDW/CSP coupling yields an atomically narrow domain wall, consisting of a single atomic layer of oxygen. This study shows that the CDW/CSP coupling is a fascinating venue to develop emergent material properties.

  6. Mechanical Properties, Microstructure and Crystallographic Texture of Magnesium AZ91-D Alloy Welded by Friction Stir Welding (FSW)

    Science.gov (United States)

    Kouadri-Henni, A.; Barrallier, L.

    2014-10-01

    The objective of the study was to characterize the properties of a magnesium alloy welded by friction stir welding. The results led to a better understanding of the relationship between this process and the microstructure and anisotropic properties of alloy materials. Welding principally leads to a large reduction in grain size in welded zones due to the phenomenon of dynamic recrystallization. The most remarkable observation was that crystallographic textures appeared from a base metal without texture in two zones: the thermo-mechanically affected and stir-welded zones. The latter zone has the peculiarity of possessing a marked texture with two components on the basal plane and the pyramidal plane. These characteristics disappeared in the thermo-mechanically affected zone (TMAZ), which had only one component following the basal plane. These modifications have been explained by the nature of the plastic deformation in these zones, which occurs at a moderate temperature in the TMAZ and high temperature in the SWZ.

  7. Crystallographic features related to a van der Waals coupling in the layered chalcogenide FePS3

    Science.gov (United States)

    Murayama, Chisato; Okabe, Momoko; Urushihara, Daisuke; Asaka, Toru; Fukuda, Koichiro; Isobe, Masahiko; Yamamoto, Kazuo; Matsushita, Yoshitaka

    2016-10-01

    We investigated the crystallographic structure of FePS3 with a layered structure using transmission electron microscopy and powder X-ray diffraction. We found that FePS3 forms a rotational twin structure with the common axis along the c*-axis. The high-resolution transmission electron microscopy images revealed that the twin boundaries were positioned at the van der Waals gaps between the layers. The narrow bands of dark contrast were observed in the bright-field transmission electron microscopy images below the antiferromagnetic transition temperature, TN ≈ 120 K. Low-temperature X-ray diffraction showed a lattice distortion; the a- and b-axes shortened and lengthened, respectively, as the temperature decreased below TN. We propose that the narrow bands of dark contrast observed in the bright-field transmission electron microscopy images are caused by the directional lattice distortion with respect to each micro-twin variant in the antiferromagnetic phase.

  8. Identification, SAR studies, and X-ray co-crystallographic analysis of a novel furanopyrimidine aurora kinase A inhibitor.

    Science.gov (United States)

    Coumar, Mohane Selvaraj; Tsai, Ming-Tsung; Chu, Chang-Ying; Uang, Biing-Jiun; Lin, Wen-Hsing; Chang, Chun-Yu; Chang, Teng-Yuan; Leou, Jiun-Shyang; Teng, Chi-Huang; Wu, Jian-Sung; Fang, Ming-Yu; Chen, Chun-Hwa; Hsu, John T-A; Wu, Su-Ying; Chao, Yu-Sheng; Hsieh, Hsing-Pang

    2010-02-01

    Herein we reveal a simple method for the identification of novel Aurora kinase A inhibitors through substructure searching of an in-house compound library to select compounds for testing. A hydrazone fragment conferring Aurora kinase activity and heterocyclic rings most frequently reported in kinase inhibitors were used as substructure queries to filter the in-house compound library collection prior to testing. Five new series of Aurora kinase inhibitors were identified through this strategy, with IC(50) values ranging from approximately 300 nM to approximately 15 microM, by testing only 133 compounds from a database of approximately 125,000 compounds. Structure-activity relationship studies and X-ray co-crystallographic analysis of the most potent compound, a furanopyrimidine derivative with an IC(50) value of 309 nM toward Aurora kinase A, were carried out. The knowledge gained through these studies could help in the future design of potent Aurora kinase inhibitors.

  9. Discovery of Pyrrolopyridine−Pyridone Based Inhibitors of Met Kinase: Synthesis, X-ray Crystallographic Analysis, and Biological Activities

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Kyoung Soon; Zhang, Liping; Schmidt, Robert; Cai, Zhen-Wei; Wei, Donna; Williams, David K.; Lombardo, Louis J.; Trainor, George L.; Xie, Dianlin; Zhang, Yaquan; An, Yongmi; Sack, John S.; Tokarski, John S.; Darienzo, Celia; Kamath, Amrita; Marathe, Punit; Zhang, Yueping; Lippy, Jonathan; Jeyaseelan, Sr., Robert; Wautlet, Barri; Henley, Benjamin; Gullo-Brown, Johnni; Manne, Veeraswamy; Hunt, John T.; Fargnoli, Joseph; Borzilleri, Robert M. (BMS)

    2008-10-02

    Conformationally constrained 2-pyridone analogue 2 is a potent Met kinase inhibitor with an IC50 value of 1.8 nM. Further SAR of the 2-pyridone based inhibitors of Met kinase led to potent 4-pyridone and pyridine N-oxide inhibitors such as 3 and 4. The X-ray crystallographic data of the inhibitor 2 bound to the ATP binding site of Met kinase protein provided insight into the binding modes of these inhibitors, and the SAR of this series of analogues was rationalized. Many of these analogues showed potent antiproliferative activities against the Met dependent GTL-16 gastric carcinoma cell line. Compound 2 also inhibited Flt-3 and VEGFR-2 kinases with IC{sub 50} values of 4 and 27 nM, respectively. It possesses a favorable pharmacokinetic profile in mice and demonstrates significant in vivo antitumor activity in the GTL-16 human gastric carcinoma xenograft model.

  10. Crystallographic and functional analyses of J-domain of JAC1 essential for chloroplast photorelocation movement in Arabidopsis thaliana.

    Science.gov (United States)

    Takano, Akira; Suetsugu, Noriyuki; Wada, Masamitsu; Kohda, Daisuke

    2010-08-01

    An auxilin-like J-domain-containing protein, JAC1, is necessary for chloroplast movement in Arabidopsis thaliana, to capture photosynthetic light efficiently under weak light conditions. Here, we performed crystallographic and functional analyses of the J-domain of JAC1. The crystal structure of the J-domain is quite similar to that of bovine auxilin, and possesses a similar positively charged surface, which probably forms the interface with the Hsp70 chaperone. The mutation of the highly conserved HPD motif of the JAC1 J-domain abrogated the chloroplast photorelocation response. These results suggest that the requirement of JAC1 in chloroplast photorelocation movement is attributable to the J-domain's cochaperone activity.

  11. The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers

    Energy Technology Data Exchange (ETDEWEB)

    Marzik, J V; Croft, W J; Staples, R J; MoberlyChan, W J

    2006-12-05

    Silicon carbide (SiC) fibers made by chemical vapor deposition (CVD) are of interest for organic, ceramic, and metal matrix composite materials due their high strength, high elastic modulus, and retention of mechanical properties at elevated processing and operating temperatures. The properties of SCS-6{trademark} silicon carbide fibers, which are made by a commercial process and consist largely of stoichiometric SiC, were compared with an experimental carbon-rich CVD SiC fiber, to which excess carbon was added during the CVD process. The concentration, homogeneity, and distribution of carbon were measured using energy dispersive x-ray spectroscopy (SEM/EDS). The effect of excess carbon on the tensile strength, elastic modulus, and the crystallographic and microstructural properties of CVD silicon carbide fibers was investigated using tensile testing, x-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

  12. Angular distribution of the emission from ultrarelativistic electrons moving near crystallographic axes in diamond and tungsten crystals

    Energy Technology Data Exchange (ETDEWEB)

    Aleinik, A.N.; Vorobev, S.A.; Kalinin, B.N.; Kurkov, A.A.; Potylitsyn, A.P.

    1986-07-01

    Data on the angular distribution of the emission from ultrarelativistic electrons moving near crystallographic axes in diamond and tungsten crystals are reviewed. A graph is presented of the orientational dependence of soft gamma rays measured by a thin-walled ionization chamber sensitive to gamma rays with energies greater than 0.3 MeV and a radiative loss measured by a total-absorption Gauss quantometer with a threshold of about 5 MeV at an angle to the primary electron-beam direction of motion. It is concluded that knowledge of the scattering processes of ultrarelativistic electrons near crytal axes makes it easier to choose the optimum type and thickness of a crystal to achieve the maximum yield of gamma radiation into a given solid angle. 8 references.

  13. Crystallographic investigation of aluminium nitride thin films on stainless steel foil for highly efficient piezoelectric vibration energy harvesters

    Science.gov (United States)

    Moriwaki, N.; Minh, L. V.; Ohigashi, R.; Shimada, O.; Kitayoshi, H.; Kuwano, H.

    2016-11-01

    This study reports piezoelectric properties and crystallographic microstructures of aluminium nitride (AlN, wurtzite structure) thin films on 50 μm thick stainless steel foil. The transverse piezoelectric coefficient d31f and e31f of 10 pm thick AlN films were estimated as -1.42 ± 0.08 μm/V and -0.48 ± 0.03 C/m2 from a tip displacement of the piezoelectric cantilevers. Dielectric constant s33 was measured as 10.5 ± 1.0. An electron beam diffraction pattern by a high-resolution transmission electron microscope and x-ray diffraction pattern showed that abundance ratio of the orientation such as , and of AlN crystal on stainless steel foils increased with increasing thickness.

  14. Electrical properties of NiAs-type MnTe films with preferred crystallographic plane of (110)

    Energy Technology Data Exchange (ETDEWEB)

    Yang, L.; Wang, Z. H., E-mail: zhwang@imr.ac.cn; Zhang, Z. D. [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016 (China)

    2016-01-28

    NiAs-type manganese telluride (MnTe) films with preferred crystallographic plane of (110) were prepared on Si/SiO{sub 2} substrates by pulsed laser deposition. X-ray diffraction (XRD) of the films was studied at different temperatures. The XRD peak of MnTe (110) films shifts to higher angle with decreasing temperature, showing the decrease of the lattice parameter. Resistivity of the films was studied in the temperature range of 2–350 K. The bump between 150 and 250 K was observed in the films, which may be related to the special s-d and p-d overlaps induced by the compressed lattice. The magnon drag effect near its Néel temperature T{sub N} and enlarged magnetic-elastic coupling below 100 K were observed and analyzed in details.

  15. Synthesis, crystallographic characterization and electrochemical property of a copper(II) complex of the anticancer agent elesclomol.

    Science.gov (United States)

    Vo, Nha Huu; Xia, Zhiqiang; Hanko, Jason; Yun, Tong; Bloom, Steve; Shen, Jianhua; Koya, Keizo; Sun, Lijun; Chen, Shoujun

    2014-01-01

    Elesclomol is a novel anticancer agent that has been evaluated in a number of late stage clinical trials. A new and convenient synthesis of elesclomol and its copper complex is described. X-ray crystallographic characterization and the electrochemical properties of the elesclomol copper(II) complex are discussed. The copper(II) cation is coordinated in a highly distorted square-planar geometry to each of the sulphur and amide nitrogen atoms of elesclomol. Electrochemical measurements demonstrate that the complex undergoes a reversible one-electron reduction at biologically accessible potentials. In contrast the free elesclomol is found electrochemically inactive. This evidence is in strong support of the mechanism of action we proposed for the anticancer activity of elesclomol.

  16. Crystallographic origin of perpendicular magnetic anisotropy in CoPt film: polarized x-ray absorption study

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, K [National University of Singapore; Chen, J [National University of Singapore; Liu, T [Oak Ridge National Laboratory (ORNL); Sun, C [Singapore Synchrotron Light Source; Chow, G [National University of Singapore

    2009-01-01

    Crystallographic structure, growth induced miscibility gap and strain in Ta/Co100 xPtx (0 x 43 at%)/Ru/Ta/glass films deposited at ambient temperature were investigated using polarized x-ray absorption spectroscopy to clarify the origin of observed perpendicular magnetic anisotropy (PMA) in Co72Pt28 film. Extended x-ray absorption fine structure spectroscopy data at Co K-edge showed that Co has a similar local atomic environment and averaged interatomic distance in the in-plane and out-of-plane polarization geometries for Co72Pt28, ruling out the contribution of magneto-elastic anisotropy and growth induced structural anisotropy as the origin of PMA. A large PMA in Co72Pt28 film was attributed to the preferred hexagonal close-packed stacking as observed using the x-ray absorption near-edge structure spectroscopy.

  17. Formation of Fast-Spread Ocean Crust : Crystallographic Preferred Orientations From a Reference Lower Crust Section in the Oman Ophiolite

    Science.gov (United States)

    Ildefonse, B.; Mueller, T.; Mock, D.; Koepke, J.

    2016-12-01

    About 20 years ago, two competing models were proposed for the formation of the lower, gabbroic crust at fast-spreading ridges. The lower crust is either formed by downward flow of mushy material from the shallow axial melt lens (gabbro glacier), or by sill intrusions (sheeted sills). To further test these end-member models, we characterized the vertical distribution of Crystallographic Preferred Orientations (CPO) in Wadi Gideah gabbro section (Sumail ophiolite, Sultanate Oman), using the Electron Backscattered Diffraction (EBSD) technique. CPO were measured on 67 gabbro samples, documenting a 5 km thick section, with an average interval of 80 m between samples. EBSD data sets were processed using MTEX, a free Matlab toolbox. Average misorientation in grains (angle between each pixel orientation and mean orientation of the grain) is very low ( 0.25°). This is consistent with magmatic flow in these rocks, and the paucity of crystal-plastic overprint. The strength (J index) of plagioclase CPO increases down-section, with a more pronounced variability in the layered gabbros. For clinopyroxene, the difference between upper (foliated) and lower (layered) gabbros is stronger, with low J in upper gabbros, and higher and more variable J in lower gabbros. In upper gabbros the symmetry of plagioclase and clinopyroxene CPO progressively evolves downward to progressively more oblate. Continuing down-section, the trend reverses, with progressively more prolate CPO in lower gabbros. The crystallographic fabric variability in the lower crust section calls for distinct formation mechanisms in the upper and lower gabbros. It is consistent with a hybrid model for crustal formation (Boudier et al., 1996, doi:10.1016/0012-821X(96)00167-7). The genesis of the upper foliated gabbro can be at least partly explained by the gabbro glacier model, while the continuous emplacement of sheeted sills at various depths is a more plausible model for the lower layered gabbro section.

  18. Erbium-ion implantation into various crystallographic cuts of Al{sub 2}O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Nekvindova, P. [Department of Inorganic Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Mackova, A.; Malinsky, P. [Nuclear Physics Institute of the Academy of Sciences of the Czech Republic v.v.i., 250 68 Rez (Czech Republic); Department of Physics, Faculty of Science, J.E. Purkinje University, Ceske mladeze 8, 400 96 Usti nad Labem (Czech Republic); Cajzl, J.; Svecova, B. [Department of Inorganic Chemistry, Institute of Chemical Technology, Technicka 5, 166 28 Prague 6 (Czech Republic); Oswald, J. [Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i., Cukrovarnicka 10, 162 53 Prague (Czech Republic); Wilhelm, R.A. [Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, 01314 Dresden (Germany); Technische Universität Dresden, 01062 Dresden (Germany)

    2015-12-15

    This paper reports on the importance of crystallographic cuts with a different orientation on the luminescent properties and structural changes of Al{sub 2}O{sub 3} implanted with Er{sup +} ions at 190 keV and with a fluence of 1.0 × 10{sup 16} cm{sup −2}. Post-implantation annealing at 1000 °C in oxygen atmosphere was also done. The chemical compositions and erbium concentration-depth profiles of implanted layers were studied by Rutherford Backscattering Spectrometry (RBS) and compared to SRIM simulations. The same value of the maximum erbium concentration (up to 2 at.%) was observed at a depth of about 40 nm for all crystallographic cuts. The structural properties of the prepared layers were characterised by RBS/channelling. The relative amount of disordered atoms of 70–80% was observed in the prepared implanted layers and discussed for various cuts. It has been found that erbium is positioned randomly in the Al{sub 2}O{sub 3} crystalline matrix, and no preferential positions appeared even after the annealing procedure. Erbium luminescence properties were measured in the wavelength range of 1440–1650 nm for all samples. As-implanted Al{sub 2}O{sub 3} samples had a significant luminescence band at 1530 nm. The best luminescence was repeatedly observed in the 〈0 0 0 1〉 cut of Al{sub 2}O{sub 3}. The annealing procedure significantly improved the luminescent properties.

  19. A binding hotspot in Trypanosoma cruzi histidyl-tRNA synthetase revealed by fragment-based crystallographic cocktail screens.

    Science.gov (United States)

    Koh, Cho Yeow; Siddaramaiah, Latha Kallur; Ranade, Ranae M; Nguyen, Jasmine; Jian, Tengyue; Zhang, Zhongsheng; Gillespie, J Robert; Buckner, Frederick S; Verlinde, Christophe L M J; Fan, Erkang; Hol, Wim G J

    2015-08-01

    American trypanosomiasis, commonly known as Chagas disease, is a neglected tropical disease caused by the protozoan parasite Trypanosoma cruzi. The chronic form of the infection often causes debilitating morbidity and mortality. However, the current treatment for the disease is typically inadequate owing to drug toxicity and poor efficacy, necessitating a continual effort to discover and develop new antiparasitic therapeutic agents. The structure of T. cruzi histidyl-tRNA synthetase (HisRS), a validated drug target, has previously been reported. Based on this structure and those of human cytosolic HisRS, opportunities for the development of specific inhibitors were identified. Here, efforts are reported to identify small molecules that bind to T. cruzi HisRS through fragment-based crystallographic screening in order to arrive at chemical starting points for the development of specific inhibitors. T. cruzi HisRS was soaked into 68 different cocktails from the Medical Structural Genomics of Pathogenic Protozoa (MSGPP) fragment library and diffraction data were collected to identify bound fragments after soaking. A total of 15 fragments were identified, all bound to the same site on the protein, revealing a fragment-binding hotspot adjacent to the ATP-binding pocket. On the basis of the initial hits, the design of reactive fragments targeting the hotspot which would be simultaneously covalently linked to a cysteine residue present only in trypanosomatid HisRS was initiated. Inhibition of T. cruzi HisRS was observed with the resultant reactive fragments and the anticipated binding mode was confirmed crystallographically. These results form a platform for the development of future generations of selective inhibitors for trypanosomatid HisRS.

  20. Bis[2-(hy-droxy-imino-meth-yl)phenolato]nickel(II): a second monoclinic polymorph.

    Science.gov (United States)

    Rusanova, Julia A; Buvaylo, Elena A; Rusanov, Eduard B

    2011-01-15

    The title compound, [Ni(C(7)H(6)NO(2))(2)], (I), is a second monoclinic polymorph of the compound, (II), reported by Srivastava et al. [Acta Cryst. (1967), 22, 922] and Mereiter [Private communication (2002) CCDC refcode NISALO01]. The bond lengths and angles are similar in both structures. The mol-ecule in both structures lies on a crystallographic inversion center and both have an inter-nal hydrogen bond. The title compound crystallizes in the space group P2(1)/c (Z = 2), whereas compound (II) is in the space group P2(1)/n (Z = 2) with a similar cell volume but different cell parameters. In both polymorphs, mol-ecules are arranged in the layers but in contrast to the previously published compound (II) where the dihedral angle between the layers is 86.3°, in the title polymorph the same dihedral angle is 29.4°. The structure of (I) is stabilized by strong intra-molecular O-H⋯O hydrogen bonding between the O-H group and the phenolate O atom.

  1. Redetermination of the crystal structure of 3,5-di-methyl-pyrazolium β-octa-molybdate tetra-hydrate.

    Science.gov (United States)

    Amarante, Tatiana R; Gonçalves, Isabel S; Almeida Paz, Filipe A

    2015-12-01

    The title compound, (C5H9N2)4[Mo8O26]·4H2O, was reported previously from a room-temperature data collection from which only the metal atoms could be refined anisotropically [FitzRoy et al. (1989 ▸). Inorg. Chim. Acta, 157, 187-194]. The current redetermination at 180 (2) K models all the non-H atoms with anisotropic displacement parameters and fully describes the supra-molecular N-H⋯O and O-H⋯O hydrogen-bonded network connecting the 3,5-di-methyl-pyrazolium cations, the water mol-ecules of crystallization and the β-octa-molybdate anion. All H atoms involved in the three-dimensional hydrogen-bonding network could be located from difference Fourier maps, with the exception of those of one disordered water mol-ecule, firstly seen in this structural report [refined over two distinct locations with site-occupancy factors of 0.65 (2) and 0.35 (2)]. The complete β-octa-molybdate anion is generated by a crystallographic inversion centre.

  2. Oxonium (dihydrogen 1-amino-ethane-1,1-diyldiphospho-nato-κN,O)[hydrogen (1-amino-1-phosphono-ethyl)phospho-nato-κN,O]palladium(II) trihydrate.

    Science.gov (United States)

    Dudko, Anatolij; Bon, Vladimir; Kozachkova, Alexandra; Tsaryk, Natalia; Pekhnyo, Vasily

    2010-01-16

    The title compound, (H(3)O)[Pd(C(2)H(7)NO(6)P(2))(C(2)H(8)NO(6)P(2))]·3H(2)O, was synthesized by the reaction of [Pd(H(2)O)(4)](NO(3))(2) with 1-amino-ethane-1,1-diyldiphospho-nic acid in aqueous solution. The asymmetric unit contains one mol-ecule of the complex existing as an anion, an oxonium counter-ion and three solvent water mol-ecules. The Pd(II) ion occupies a position on a pseudo-twofold axis, which is not realized crystallographically. The slightly distorted square-planar coordination environment of the Pd(II) ion consists of the O atoms from two phospho-nic acid groups and two N atoms of the amino groups in cis positions. The crystal structure displays N-H⋯O and O-H⋯O hydrogen bonding, which creates a wide three-dimensional network.

  3. Non-Crystallographic Layer Lattice Restrictions in Order-Disorder (OD Structures

    Directory of Open Access Journals (Sweden)

    Berthold Stöger

    2014-07-01

    Full Text Available Symmetry operations of layers periodic in two dimensions restrict the geometry the lattice according to the five two-dimensional Bravais types of lattices. In order-disorder (OD structures, the operations relating equivalent layers generally leave invariant only a sublattice of the layers. The thus resulting restrictions can be expressed in terms of linear relations of the a2, b2 and a · b scalar products of the lattice basis vectors with rational coefficients. To characterize OD families and to check their validity, these lattice restrictions are expressed in the bases of different layers and combined. For a more familiar notation, they can be expressed in terms of the lattice parameters a, b and . Alternatively, the description of the lattice restrictions may be simplified by using centered lattices. The representation of the lattice restrictions in terms of scalar products is dependent on the chosen basis. A basis-independent classification of the lattice restrictions is outlined.

  4. Similar quartz crystallographic textures in rocks of continental earth's crust (by neutron diffraction data): II. Quartz textures in monophase rocks

    Energy Technology Data Exchange (ETDEWEB)

    Nikitin, A. N., E-mail: nikitin@nf.jinr.ru; Ivankina, T. I. [Joint Institute for Nuclear Research (Russian Federation); Ullemeyer, K. [Universitaet Kiel, Institut fuer Geowissenschaften (Germany); Vasin, R. N. [Joint Institute for Nuclear Research (Russian Federation)

    2008-09-15

    The types of quartz textures found in a large collection of multiphase rocks from different regions of the earth are analyzed. Crystallographic textures of granulite, amphibolite, slate, and gneiss samples are measured, classified, and compared with the similar textures of monomineral rocks.

  5. Software developments in automated structure solution and crystallographic studies of the Sso10a2 and human C1 inhibitor protein

    NARCIS (Netherlands)

    Waterreus, Willem-Jan

    2013-01-01

    CRANK is a suite that links different macromolecular X-ray crystallographic programs to solve macromolecular crystal structures automatically from experimental phasing data. In chapter 2, several new algorithms implemented within CRANK increase the robustness and speed of the structure solution proc

  6. Crystallographic dependent in-situ CBr4 selective nano-area etching and local regrowth of InP/InGaAs by MOVPE

    DEFF Research Database (Denmark)

    Kuznetsova, Nadezda; Kulkova, Irina; Semenova, Elizaveta;

    2014-01-01

    Selective area etching and growth in the metalorganic vapor phase epitaxy (MOVPE) reactor on nano-scale structures have been examined. Using different mask orientations, crystallographic dependent etching of InP can be observed when carbon tetrabromide (CBr4) is used as an etchant. Scanning Elect...

  7. Crystallographic Analysis of Isothermally Transformed Bainite in 0.2C-2.0Mn-1.5Si-0.6Cr Steel Using EBSD

    Institute of Scientific and Technical Information of China (English)

    Pasi P.Suikkanen; Cyril Cayron; Anthony J.DeArdo; L.Pentti Karjalainen

    2013-01-01

    The crystallography of bainite,transformed isothermally at 450 ℃ in 0.2C-2.0Mn-1.5Si-O.6Cr steel,was investigated by electron backscatter diffraction (EBSD) analysis.The orientation relationship (OR) was found to be closer to Nishiyama-Wassermann (N-W) than Kurdjumov-Sachs orientation relationship.Bainite microstructure consisted of parallel laths forming a morphological packet structure.Typically,there were three different lath orientations in a morphological packet.These orientations were dictated by a three specific N-W OR variants sharing the same {111} austenite plane.A packet of bainite laths with common {111}austenite plane was termed as crystallographic packet.Generally,the crystallographic packet size corresponded to the morphological packet size.Locally,crystallographic packets with only two dominant orientations were observed.This indicates strong local variant selection during isothermal bainite transformation.The relative orientation between the variants in crystallographic packets was found to be near 60°/<110>.This appears to explain the strong peak observed in the grain boundary misorientation distribution near 60°.Bainite also contained pronounced fraction of boundaries with their misorientation in the range of 2.5°-8° with quite widely dispersed rotation angles.Spatially these boundaries were found to locate inside the bainite laths,forming lath-like sub-grains.

  8. Thermodynamics of Condensed Phases: Formula Unit Volume, "V[subscript m]", and the Determination of the Number of Formula Units, "Z", in a Crystallographic Unit Cell

    Science.gov (United States)

    Glasser, Leslie

    2011-01-01

    Formula unit (or molecular) volume, "V[subscript m]", is related to many thermodynamic and physical properties of materials, so that knowledge of "V[subscript m]" is useful in prediction of such properties for known and even hypothetical materials. The symbol "Z" represents the number of formula units in a crystallographic unit cell; "Z" thus…

  9. Beeping a Maximal Independent Set

    OpenAIRE

    Afek, Yehuda; Alon, Noga; Bar-Joseph, Ziv; Cornejo, Alejandro; Haeupler, Bernhard; Kuhn, Fabian

    2012-01-01

    We consider the problem of computing a maximal independent set (MIS) in an extremely harsh broadcast model that relies only on carrier sensing. The model consists of an anonymous broadcast network in which nodes have no knowledge about the topology of the network or even an upper bound on its size. Furthermore, it is assumed that an adversary chooses at which time slot each node wakes up. At each time slot a node can either beep, that is, emit a signal, or be silent. At a particular time slot...

  10. ]Space Shuttle Independent Assessment Team

    Science.gov (United States)

    2000-01-01

    The Shuttle program is one of the most complex engineering activities undertaken anywhere in the world at the present time. The Space Shuttle Independent Assessment Team (SIAT) was chartered in September 1999 by NASA to provide an independent review of the Space Shuttle sub-systems and maintenance practices. During the period from October through December 1999, the team led by Dr. McDonald and comprised of NASA, contractor, and DOD experts reviewed NASA practices, Space Shuffle anomalies, as well as civilian and military aerospace experience. In performing the review, much of a very positive nature was observed by the SIAT, not the least of which was the skill and dedication of the workforce. It is in the unfortunate nature of this type of review that the very positive elements are either not mentioned or dwelt upon. This very complex program has undergone a massive change in structure in the last few years with the transition to a slimmed down, contractor-run operation, the Shuttle Flight Operations Contract (SFOC). This has been accomplished with significant cost savings and without a major incident. This report has identified significant problems that must be addressed to maintain an effective program. These problems are described in each of the Issues, Findings or Observations summarized, and unless noted, appear to be systemic in nature and not confined to any one Shuttle sub-system or element. Specifics are given in the body of the report, along with recommendations to improve the present systems.

  11. Independent EEG sources are dipolar.

    Directory of Open Access Journals (Sweden)

    Arnaud Delorme

    Full Text Available Independent component analysis (ICA and blind source separation (BSS methods are increasingly used to separate individual brain and non-brain source signals mixed by volume conduction in electroencephalographic (EEG and other electrophysiological recordings. We compared results of decomposing thirteen 71-channel human scalp EEG datasets by 22 ICA and BSS algorithms, assessing the pairwise mutual information (PMI in scalp channel pairs, the remaining PMI in component pairs, the overall mutual information reduction (MIR effected by each decomposition, and decomposition 'dipolarity' defined as the number of component scalp maps matching the projection of a single equivalent dipole with less than a given residual variance. The least well-performing algorithm was principal component analysis (PCA; best performing were AMICA and other likelihood/mutual information based ICA methods. Though these and other commonly-used decomposition methods returned many similar components, across 18 ICA/BSS algorithms mean dipolarity varied linearly with both MIR and with PMI remaining between the resulting component time courses, a result compatible with an interpretation of many maximally independent EEG components as being volume-conducted projections of partially-synchronous local cortical field activity within single compact cortical domains. To encourage further method comparisons, the data and software used to prepare the results have been made available (http://sccn.ucsd.edu/wiki/BSSComparison.

  12. 5-Iodo-3-phenyl-2,1-benzoxazole.

    Science.gov (United States)

    Teslenko, Yuriy; Matiychuk, Vasyl S; Kinzhybalo, Vasyl; Lis, Tadeusz; Obushak, Mykola D

    2013-04-01

    The title compound, C13H8INO, was prepared by a condensation reaction of 4-nitro-benzene with phenyl-acetonitrile in NaOH-ethanol solution. There are two independent mol-ecules in the asymmetric unit, in which the dihedral angles between the benzene ring and the benzoisoxazole unit are 4.2 (3) and 4.1 (3)°. The crystal packing is governed by C-H⋯N, C-I⋯π and C-I⋯O inter-actions.

  13. Ethyl 6-methyl-4-[2-(4,4,5,5-tetra-methyl-1,3,2-dioxaborolan-2-yl)thio-phen-3-yl]-2-thioxo-1,2,3,4-tetra-hydro-pyrimidine-5-carboxyl-ate.

    Science.gov (United States)

    Decken, Andreas; Zamora, Matthew T; Duguay, Dominique R; Vogels, Christopher M; Westcott, Stephen A

    2008-04-26

    A new Biginelli compound, C(18)H(25)BN(2)O(4)S(2), containing a boronate ester group was synthesized from a lithium bromide-catalysed reaction. The compound crystallizes with two independent mol-ecules in the asymmetric unit that differ mainly in the conformation of the ester functionality. The crystal structure is stabilized by inter-molecular N-H⋯O and N-H⋯S hydrogen bonds involving the 3,4-dihydro-pyrimidine-2(1H)-thione NH groups as donors and the carbonyl O and thio-phene S atoms as acceptors.

  14. 2,4-Dichloro-N-(2,5-dimethyl-phen-yl)benzene-sulfonamide.

    Science.gov (United States)

    Rodrigues, Vinola Z; Foro, Sabine; Gowda, B Thimme

    2011-10-01

    The asymmetric unit of the title compound, C(14)H(13)Cl(2)NO(2)S, contains three independent moleules. The torsion angles of the C-SO2-NH-C segments in the three mol-ecules are 67.5 (2), 83.4 (2) and -77.5 (2)°. The two aromatic rings are tilted relative to each other by 68.8 (1), 64.1 (1) and 68.5 (1)°. The crystal structure features dimers linked by pairs of N-H⋯O hydrogen bonds.

  15. On Judicial and Quasi-Judicial Independence

    NARCIS (Netherlands)

    Comtois, Suzanne; de Graaf, K.J.

    2013-01-01

    'Principles of judicial and quasi-judicial independence are fundamental to all democracies and yet, the notion of independence is still elusive. What is judicial and quasi-judicial independence and why is it important? From whom and what are the judiciary and other adjudicators to be independent? Is

  16. Microscopic, crystallographic and adherence properties of plasma-sprayed calcium phosphate coatings on Ti-6Al-4V

    Science.gov (United States)

    Tufekci, Eser

    Recently, plasma-spayed titanium implants have become very popular in the dentistry because of their biocompatibility and ability of providing osseointegration with the surrounding bone. Although there are numerous published studies on these materials, information and standards are still lacking. This study investigated the miscrostructural, crystallographic and adherence properties of plasma-sprayed hydroxyapatite coatings on Ti-6Al-4V substrates. The microstructures of the coatings and the elemental interdiffusion near the coating/substrate interface were investigated using a scanning electron microscope (SEM) equipped with x-ray energy-dispersive spectroscopy (EDS). X-ray diffraction analyses performed on Ti-6Al-4V coupons prepared with different percent crystallinities have provided structural information such as degree of crystallinity, phases present, average crystallite size, as well as the residual stresses within the coating. For evaluation of the adherence of the coatings to the substrates, experimental rods were subjected to torsion. The fracture surfaces were analyzed using SEM/EDS to develop a new methodology to determine the percent adherence of the coatings. SEM studies indicated that the surface microstructures of commercial dental implants were consistent with the plasma-spraying. In cross-section, coatings exhibited minimal porosity and limited interdiffusion of titanium and calcium at the coating/substrate interface. X-ray diffraction analyses indicated that the highest crystallinity coatings consisted of almost entirely HA and an amorphous calcium phosphate phase. As the coating crystallinity decreased, increasing amounts of alpha- and beta-tricalcium phosphate and tetracalcium phosphate were detected. The mean percent crystallinity for the three sets of coatings ranged from 50-60%. The mean HA crystallite size for the three sets of coatings ranged from about 0.02-0.04 mum. Differences in mean interplanar spacings for three selected

  17. Crystallographic Fabrics, Grain Boundary Microstructure and Shape Preferred Orientation of Deformed Banded Iron Formations and their Significance for Deformation Interpretation

    Science.gov (United States)

    Ávila, Carlos Fernando; Graça, Leonardo; Lagoeiro, Leonardo; Ferreira, Filippe

    2016-04-01

    The characterization of grain boundaries and shapes along with crystallographic preferred orientations (CPOs) are a key aspect of investigations of rock microstructures for their correlation with deformation mechanisms. Rapid developments have occurred in the studying rock microstructures due to recent improvements in analytical techniques such as Electron Backscatter Diffraction (EBSD). EBSD technique allows quick automated microtextural characteritzation. The deformed banded iron formations (BIFs) occurring in the Quadrilátero Ferrífero (QF) province in Brazil have been studied extensively with EBSD. All studies have focused mainly in CPOs. The general agreement is that dislocation creep was the dominant process of deformation, for the strong c-axis fabric of hematite crystals. This idea is substantiated by viscoplastic self-consistent models for deformation of hematite. However there are limitations to analyzing natural CPOs alone, or those generated by deformation models. The strong c-axis fabric could be taken as equally powerful an evidence for other known deformation mechanisms. Some grain boundary types in BIFs of the QF are irregular and comprise equant grains in granoblastic texture (Figure 1a). CPOs for this kind are strong and consistent with a predominance of dislocation creep. Others are very regular and long parallel to basal planes of hematites forming large elongated crystals (lepidoblastic texture, Figure 1b). Such crystals are called specularite, and their formation has been previously attributed to dislocation creep. This is erroneous because of the high strains which would be required. Their shape must be due to anisotropic grain growth. Other types lie between the above end-textures. Both types of grain shape microstructures have the same core deformation mechanism. Describing their genetic differences is crucial, since specularite owe its shape to anisotropic grain growth. It is not possible yet to confirm that dislocation creep was the

  18. The Symbolic Independence From Power

    Directory of Open Access Journals (Sweden)

    Luisa Muraro

    2009-05-01

    Full Text Available Muraro’s article begins from the philosophical question of the ‘unthought’, and asks how our very image of thought is transformed when the thinking subject is a woman, and her thought is specifically linked to the experience of a body. On the basis of a feminist interrogation of sexual difference which reveals the forms of violence inherent in certain claims to universality, Muraro tries to develop a thinking of politics which would rest on its symbolic distance or independence from power. Through readings of Freud, Macbeth, Saint Paul and women’s narratives, Muraro investigates the dangers borne by the fusion of power and politics and explores the ways in which they could be disjoined.

  19. Platform-Independent Courseware Sharing

    Directory of Open Access Journals (Sweden)

    Takao Shimomura

    2013-04-01

    Full Text Available Courseware distribution between different platforms is the major issue of current e-Learning. SCORM (Sharable Content Object Reference Model is one of the solutions for courseware sharing. However, to make SCORM-conformable courseware, some knowledge about HTML and JavaScript is required. This paper presents a SWF (Sharable Web Fragment-based e-Learning system, where courseware is created with sharable Web fragments such as Web pages, images and other resources, and the courseware can be distributed to another platform by export and import facilities. It also demonstrates how to export a subject that contains assignments and problems and how to import the whole subject, only the assignments, or only the problems. The exported meta-information is architecture-independent and provides a model of courseware distribution.

  20. Ergodic theory independence and dichotomies

    CERN Document Server

    Kerr, David

    2016-01-01

    This book provides an introduction to the ergodic theory and topological dynamics of actions of countable groups. It is organized around the theme of probabilistic and combinatorial independence, and highlights the complementary roles of the asymptotic and the perturbative in its comprehensive treatment of the core concepts of weak mixing, compactness, entropy, and amenability. The more advanced material includes Popa's cocycle superrigidity, the Furstenberg-Zimmer structure theorem, and sofic entropy. The structure of the book is designed to be flexible enough to serve a variety of readers. The discussion of dynamics is developed from scratch assuming some rudimentary functional analysis, measure theory, and topology, and parts of the text can be used as an introductory course. Researchers in ergodic theory and related areas will also find the book valuable as a reference.

  1. Model Independent Direct Detection Analyses

    CERN Document Server

    Fitzpatrick, A Liam; Katz, Emanuel; Lubbers, Nicholas; Xu, Yiming

    2012-01-01

    Following the construction of the general effective theory for dark matter direct detection in 1203.3542, we perform an analysis of the experimental constraints on the full parameter space of elastically scattering dark matter. We review the prescription for calculating event rates in the general effective theory and discuss the sensitivity of various experiments to additional nuclear responses beyond the spin-independent (SI) and spin-dependent (SD) couplings: an angular-momentum-dependent (LD) and spin-and-angular-momentum-dependent (LSD) response, as well as a distinction between transverse and longitudinal spin-dependent responses. We consider the effect of interference between different operators and in particular look at directions in parameter space where such cancellations lead to holes in the sensitivity of individual experiments. We explore the complementarity of different experiments by looking at the improvement of bounds when experiments are combined. Finally, our scan through parameter space sho...

  2. Prediction of molecular crystal structures by a crystallographic QM/MM model with full space-group symmetry.

    Science.gov (United States)

    Mörschel, Philipp; Schmidt, Martin U

    2015-01-01

    A crystallographic quantum-mechanical/molecular-mechanical model (c-QM/MM model) with full space-group symmetry has been developed for molecular crystals. The lattice energy was calculated by quantum-mechanical methods for short-range interactions and force-field methods for long-range interactions. The quantum-mechanical calculations covered the interactions within the molecule and the interactions of a reference molecule with each of the surrounding 12-15 molecules. The interactions with all other molecules were treated by force-field methods. In each optimization step the energies in the QM and MM shells were calculated separately as single-point energies; after adding both energy contributions, the crystal structure (including the lattice parameters) was optimized accordingly. The space-group symmetry was maintained throughout. Crystal structures with more than one molecule per asymmetric unit, e.g. structures with Z' = 2, hydrates and solvates, have been optimized as well. Test calculations with different quantum-mechanical methods on nine small organic molecules revealed that the density functional theory methods with dispersion correction using the B97-D functional with 6-31G* basis set in combination with the DREIDING force field reproduced the experimental crystal structures with good accuracy. Subsequently the c-QM/MM method was applied to nine compounds from the CCDC blind tests resulting in good energy rankings and excellent geometric accuracies.

  3. Crystallographic Identification of Lipid as an Integral Component of the Epitope of HIV Broadly Neutralizing Antibody 4E10.

    Science.gov (United States)

    Irimia, Adriana; Sarkar, Anita; Stanfield, Robyn L; Wilson, Ian A

    2016-01-19

    Numerous studies of the anti-HIV-1 envelope glycoprotein 41 (gp41) broadly neutralizing antibody 4E10 suggest that 4E10 also interacts with membrane lipids, but the antibody regions contacting lipids and its orientation with respect to the viral membrane are unknown. Vaccine immunogens capable of re-eliciting these membrane proximal external region (MPER)-like antibodies may require a lipid component to be successful. We performed a systematic crystallographic study of lipid binding to 4E10 to identify lipids bound by the antibody and the lipid-interacting regions. We identified phosphatidic acid, phosphatidylglycerol, and glycerol phosphate as specific ligands for 4E10 in the crystal structures. 4E10 used its CDRH1 loop to bind the lipid head groups, while its CDRH3 interacted with the hydrophobic lipid tails. Identification of the lipid binding sites on 4E10 may aid design of immunogens for vaccines that include a lipid component in addition to the MPER on gp41 for generation of broadly neutralizing antibodies.

  4. Enzyme transient state kinetics in crystal and solution from the perspective of a time-resolved crystallographer.

    Science.gov (United States)

    Schmidt, Marius; Saldin, Dilano K

    2014-03-01

    With recent technological advances at synchrotrons [Graber et al., J. Synchrotron Radiat. 18, 658-670 (2011)], it is feasible to rapidly collect time-resolved crystallographic data at multiple temperature settings [Schmidt et al., Acta Crystallogr. D 69, 2534-2542 (2013)], from which barriers of activation can be extracted. With the advent of fourth generation X-ray sources, new opportunities emerge to investigate structure and dynamics of biological macromolecules in real time [M. Schmidt, Adv. Condens. Matter Phys. 2013, 1-10] in crystals and potentially from single molecules in random orientation in solution [Poon et al., Adv. Condens. Matter Phys. 2013, 750371]. Kinetic data from time-resolved experiments on short time-scales must be interpreted in terms of chemical kinetics [Steinfeld et al., Chemical Kinetics and Dynamics, 2nd ed. (Prentience Hall, 1985)] and tied to existing time-resolved experiments on longer time-scales [Schmidt et al., Acta Crystallogr. D 69, 2534-2542 (2013); Jung et al., Nat. Chem. 5, 212-220 (2013)]. With this article, we will review and outline steps that are required to routinely determine the energetics of reactions in biomolecules in crystal and solution with newest X-ray sources. In eight sections, we aim to describe concepts and experimental details that may help to inspire new approaches to collect and interpret these data.

  5. Crystallographic characterization of the radixin FERM domain bound to the cytoplasmic tail of adhesion molecule CD44

    Energy Technology Data Exchange (ETDEWEB)

    Mori, Tomoyuki; Kitano, Ken; Terawaki, Shin-ichi; Maesaki, Ryoko; Hakoshima, Toshio, E-mail: hakosima@bs.naist.jp [Structural Biology Laboratory, Nara Institute of Science and Technology, Keihanna Science City, Nara 630-0192 (Japan)

    2007-10-01

    The radixin FERM domain complexed with the CD44 cytoplasmic tail peptide has been crystallized. A diffraction data set from the complex was collected to 2.1 Å. CD44 is an important adhesion molecule that specifically binds hyaluronic acid and regulates cell–cell and cell–matrix interactions. Increasing evidence has indicated that CD44 is assembled in a regulated manner into the membrane–cytoskeletal junction, a process that is mediated by ERM (ezrin/radixin/moesin) proteins. Crystals of a complex between the radixin FERM domain and the C-terminal cytoplasmic region of CD44 have been obtained. The crystal of the radixin FERM domain bound to the CD44 cytoplasmic tail peptide belongs to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 62.70, b = 66.18, c = 86.22 Å, and contain one complex in the crystallographic asymmetric unit. An intensity data set was collected to a resolution of 2.1 Å.

  6. Coordination Compounds of Niobium(IV) Oxide Dihalides Including the Synthesis and the Crystallographic Characterization of NHC Complexes.

    Science.gov (United States)

    Bortoluzzi, Marco; Ferretti, Eleonora; Marchetti, Fabio; Pampaloni, Guido; Pinzino, Calogero; Zacchini, Stefano

    2016-05-01

    The 1:1 molar reactions of NbOX3 with SnBu3H, in toluene at 0 °C in the presence of oxygen/nitrogen donors, resulted in the formation of NbOX2L2 (X = Cl, L2 = dme, 2a; X = Br, L2 = dme, 2b; X = Cl, L = thf, 2c; X = Cl, L = NCMe, 2d; dme = 1,2-dimethoxyethane, thf = tetrahydrofuran), in good yields. The 1:2 reactions of freshly prepared 2d and 2b with the bulky NHC ligands 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, Imes, and 1,3-bis(2,6-dimethylphenyl)imidazol-2-ylidene, Ixyl, respectively, afforded the complexes NbOCl2(Imes)2, 3, and NbOBr2(Ixyl)2, 4, in 50-60% yields. The reactions of 2b with NaOR, in tetrahydrofuran, gave NbOCl(OR) (R = Ph, 5; R = Me, 6) in about 60% yields. All the products were characterized by analytical and spectroscopic techniques; moreover DFT calculations were carried out in order to shed light on synthetic and structural features. Compounds 3 and 4, whose molecular structures have been ascertained by X-ray diffraction, represent very rare examples of crystallographically characterized niobium-NHC systems.

  7. The SecB-like chaperone Rv1957 from Mycobacterium tuberculosis: crystallization and X-ray crystallographic analysis.

    Science.gov (United States)

    Lu, Zuokun; Wang, Han; Yu, TingTing

    2016-06-01

    Protein export is important in all bacteria, and bacteria have evolved specialized export machineries to fulfil this task. In Mycobacterium tuberculosis, the causative agent of tuberculosis, the general secretion pathway (Sec pathway) is conserved and is essential in performing the export of proteins. The bacterial Sec pathway post-translationally exports unfolded proteins out of the cytoplasm, and the core of the Sec pathway is composed of a heterotrimeric membrane-embedded channel, SecYEG, and two cytosolic components, SecA and SecB. SecB functions by stabilizing unfolded proteins, maintaining them in an export-competent state. Although SecB is mainly found in Proteobacteria, a SecB-like protein, Rv1957, that controls a stress-response toxin-antitoxin system, is found in M. tuberculosis. Rv1957 can also functionally replace the Escherichia coli SecB chaperone both in vivo and in vitro. In this work, the production, crystallization and X-ray crystallographic analysis of Rv1957 are reported. Notably, diffraction-quality crystals were obtained only at high concentrations of dimethyl sulfoxide, i.e. about 12%(v/v). The crystals of Rv1957 belonged to space group P212121, with unit-cell parameters a = 64.5, b = 92.0, c = 115.4 Å.

  8. Purification, crystallization and preliminary X-ray crystallographic analysis of the CIDE-N domain of Fsp27.

    Science.gov (United States)

    Wang, Xiaodan; Zhang, Bo; Xu, Duo; Gao, Jinlan; Wang, Linfang; Wang, Zhi; Shan, Yaming; Yu, Xianghui

    2012-12-01

    Fsp27, a member of the CIDE protein family which is selectively expressed in adipocytes, has emerged as a novel regulator for unilocular lipid droplet (LD) formation, lipid metabolism, differentiation of adipocytes and insulin sensitivity. An LD is a subcellular compartment that is used by adipocytes for the efficient storage of fats. The CIDE-N domain of Fsp27 functions as a recruitment platform that induces the correct configuration of the Fsp27 CIDE-C domain to facilitate LD fusion. This study reports the high-yield expression of the mouse Fsp27 CIDE-N domain in Escherichia coli; a two-step purification protocol with high efficiency was established and crystallographic analysis was performed. The purity of the recombinant Fsp27 was >95% as assessed by SDS-PAGE. Crystals were obtained at 291 K using 28% polyethylene glycol 4000 as a precipitant. Diffraction data were collected to 1.92 Å resolution and the crystal belonged to space group P6(5), with unit-cell parameters a=b=63.3, c=37.4 Å, α=β=90, γ=120°. The components of the crystal were identified by ion-trap LC/MS/MS spectrometric analysis. The structure has been solved by molecular replacement and refinement is in progress.

  9. Crystallization and preliminary X-ray crystallographic analysis of polyphenol oxidase from Juglans regia (jrPPO1)

    Energy Technology Data Exchange (ETDEWEB)

    Zekiri, Florime; Bijelic, Aleksandar; Molitor, Christian; Rompel, Annette, E-mail: annette.rompel@univie.ac.at [Universität Wien, Althanstrasse 14, 1090 Wien (Austria)

    2014-05-28

    The crystallization and preliminary X-ray crystallographic analysis of a plant PPO exhibiting monophenolase activity from J. regia (jrPPO1) in its active form (Asp{sup 101}–Arg{sup 445}) are reported. Tyrosinase is a type 3 copper enzyme that catalyzes the ortho-hydroxylation of monophenols to diphenols as well as their subsequent oxidation to quinones, which are precursors for the biosynthesis of melanins. The first plant tyrosinase from walnut leaves (Juglans regia) was purified to homogeneity and crystallized. During the purification, two forms of the enzyme differing only in their C-termini [jrPPO1(Asp{sup 101}–Pro{sup 444}) and jrPPO1(Asp{sup 101}–Arg{sup 445})] were obtained. The most abundant form jrPPO1(Asp{sup 101}–Arg{sup 445}), as described in Zekiri et al. [Phytochemistry (2014 ▶), 101, 5–15], was crystallized, resulting in crystals that belonged to space group C121, with unit-cell parameters a = 115.56, b = 91.90, c = 86.87 Å, α = 90, β = 130.186, γ = 90°, and diffracted to 2.39 Å resolution. Crystals were only obtained from solutions containing at least 30% polyethylene glycol 5000 monomethyl ether in a close-to-neutral pH range.

  10. Crystallization and preliminary crystallographic studies of LipA, a secretory lipase/esterase from Xanthomonas oryzae pv. oryzae

    Energy Technology Data Exchange (ETDEWEB)

    Aparna, Gudlur; Chatterjee, Avradip; Jha, Gopaljee; Sonti, Ramesh V.; Sankaranarayanan, Rajan, E-mail: sankar@ccmb.res.in [Centre for Cellular and Molecular Biology, Uppal Road, Hyderabad 500 007 (India)

    2007-08-01

    The crystallization and preliminary crystallographic studies of LipA, a lipase/esterase secreted by X. oryzae pv. oryzae during its infection of rice plants, are reported. Xanthomonas oryzae pv. oryzae is the causal agent of bacterial leaf blight, a serious disease of rice. Several enzymes that are secreted through the type II secretion system of this bacterium play an important role in the plant–microbe interaction, being important for virulence and also being able to induce potent host defence responses. One of these enzymes is a secretory lipase/esterase, LipA, which shows a very weak homology to other bacterial lipases and gives a positive tributyrin plate assay. In this study, LipA was purified from the culture supernatant of an overexpressing clone of X. oryzae pv. oryzae and two types of crystals belonging to space group C2 but with two different unit-cell parameters were obtained using the hanging-drop vapour-diffusion method. Type I crystals diffract to a maximum resolution of 1.89 Å and have unit-cell parameters a = 93.1, b = 62.3, c = 66.1 Å, β = 90.8°. Type II crystals have unit-cell parameters a = 103.6, b = 54.6, c = 66.3 Å, β = 92.6° and diffract to 1.86 Å. Solvent-content analysis shows one monomer in the asymmetric unit in both the crystal forms.

  11. Purification, crystallization and preliminary crystallographic analysis of KatB, a manganese catalase from Anabaena PCC 7120.

    Science.gov (United States)

    Bihani, Subhash Chandra; Chakravarty, Dhiman; Ballal, Anand

    2013-11-01

    Catalases are enzymes that play an important role in the detoxification of hydrogen peroxide (H2O2) in aerobic organisms. Among catalases, haem-containing catalases are ubiquitously distributed and their enzymatic mechanism is very well understood. On the other hand, manganese catalases that contain a bimanganese core in the active site have been less well characterized and their mode of action is not fully understood. The genome of Anabaena PCC 7120 does not show the presence of a haem catalase-like gene; instead, two ORFs encoding manganese catalases (Mn-catalases) are present. Here, the crystallization and preliminary X-ray crystallographic analysis of KatB, one of the two Mn-catalases from Anabaena, are reported. KatB was crystallized using the hanging-drop vapour-diffusion method with PEG 400 as a precipitant and calcium acetate as an additive. Diffraction data were collected in-house on an Agilent SuperNova system using a microfocus sealed-tube X-ray source. The crystal diffracted to 2.2 Å resolution at 100 K. The tetragonal crystal belonged to space group P4(1)2(1)2 (or enantiomer), with unit-cell parameters a = b = 101.87, c = 138.86 Å. Preliminary X-ray diffraction analysis using the Matthews coefficient and self-rotation function suggests the presence of a trimer in the asymmetric unit.

  12. Superior Pre-Osteoblast Cell Response of Etched Ultrafine-Grained Titanium with a Controlled Crystallographic Orientation

    Science.gov (United States)

    Baek, Seung Mi; Shin, Myeong Hwan; Moon, Jongun; Jung, Ho Sang; Lee, See Am; Hwang, Woonbong; Yeom, Jong Taek; Hahn, Sei Kwang; Kim, Hyoung Seop

    2017-03-01

    Ultrafine-grained (UFG) Ti for improved mechanical performance as well as its surface modification enhancing biofunctions has attracted much attention in medical industries. Most of the studies on the surface etching of metallic biomaterials have focused on surface topography and wettability but not crystallographic orientation, i.e., texture, which influences the chemical as well as the physical properties. In this paper, the influences of texture and grain size on roughness, wettability, and pre-osteoblast cell response were investigated in vitro after HF etching treatment. The surface characteristics and cell behaviors of ultrafine, fine, and coarse-grained Ti were examined after the HF etching. The surface roughness during the etching treatment was significantly increased as the orientation angle from the basal pole was increased. The cell adhesion tendency of the rough surface was promoted. The UFG Ti substrate exhibited a higher texture energy state, rougher surface, enhanced hydrophilic wettability, and better cell adhesion and proliferation behaviors after etching than those of the coarse- and fine-grained Ti substrates. These results provide a new route for enhancing both mechanical and biological performances using etching after grain refinement of Ti.

  13. Analysis of the structural continuity in twinned crystals in terms of pseudo-eigensymmetry of crystallographic orbits

    Directory of Open Access Journals (Sweden)

    Mohamed Amine Marzouki

    2014-01-01

    Full Text Available The reticular theory of twinning gives the necessary conditions on the lattice level for the formation of twins. The latter are based on the continuation, more or less approximate, of a substructure through the composition surface. The analysis of this structural continuity can be performed in terms of the eigensymmetry of the crystallographic orbits corresponding to occupied Wyckoff positions in the structure. If {\\cal G} is the space group of the individual and {\\cal H} a space group which fixes the twin lattice obtained as an intersection of the space groups of the individuals in their respective orientations, then a structural continuity is obtained if (1 the eigensymmetry of an orbit under {\\cal G} contains the twin operation; (2 the eigensymmetry of a union of orbits under {\\cal G} contains the twin operation; (3 the eigensymmetry of a split orbit under {\\cal H} contains the twin operation; or (4 the eigensymmetry of a union of split orbits under {\\cal H} contains the twin operation. The case of the twins in melilite is analysed: the (approximate restoration of some of the orbits explains the formation of these twins.

  14. Crystallographic structure and energetics of the Rh(1 0 0)-(3 × 1)-2O phase

    Science.gov (United States)

    Kißlinger, T.; Ferstl, P.; Schneider, M. A.; Hammer, L.

    2017-09-01

    In this study we investigate the crystallographic structure of the Rh(1 0 0)-(3×1 )-2O phase by quantitative low energy electron diffraction (LEED) and scanning tunnelling microscopy as well as the energetics of the system applying density functional theory calculations (DFT). The (3×1 ) structure forms upon exposing the clean Rh(1 0 0) surface to 1200 L of oxygen at 520 K. A full-dynamical LEED intensity analysis (Pendry R-factor R= 0.095 ) reveals an oxygen-induced shifted row-reconstruction of the rhodium top layer where every third Rh-row is displaced by half a surface lattice parameter along the [0 1 1]-direction. There are two oxygen atoms within the unit cell which assume threefold coordinated sites on both sides of the shifted Rh-row with one bond to the shifted and two bonds to the unshifted rows. DFT calculations yield a total energy gain of 0.27 eV per oxygen atom compared to adsorption on the unreconstructed surface. This by far overcompensates the energetic penalty of 0.10 eV per oxygen atom for shifting the Rh-row and thus drives the substrate reconstruction. A coadsorption of oxygen at remaining regular sites of the substrate is not observed in experiment and is found to be energetically unfavorable.

  15. Crystallographic origin of perpendicular magnetic anisotropy in CoPt film: polarized x-ray absorption study

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, K.K.M.; Chen, J.S.; Liu, T.; Sun, C.J.; Chow, G.M.; (NU Sinapore); (ORNL)

    2009-09-17

    Crystallographic structure, growth induced miscibility gap and strain in Ta/Co{sub 100-x}Pt{sub x} (0 {le} x {le} 43 at%)/Ru/Ta/glass films deposited at ambient temperature were investigated using polarized x-ray absorption spectroscopy to clarify the origin of observed perpendicular magnetic anisotropy (PMA) in Co{sub 72}Pt{sub 28} film. Extended x-ray absorption fine structure spectroscopy data at Co K-edge showed that Co has a similar local atomic environment and averaged interatomic distance in the in-plane and out-of-plane polarization geometries for Co{sub 72}Pt{sub 28}, ruling out the contribution of magneto-elastic anisotropy and growth induced structural anisotropy as the origin of PMA. A large PMA in Co{sub 72}Pt{sub 28} film was attributed to the preferred hexagonal close-packed stacking as observed using the x-ray absorption near-edge structure spectroscopy.

  16. Enzyme transient state kinetics in crystal and solution from the perspective of a time-resolved crystallographer

    Directory of Open Access Journals (Sweden)

    Marius Schmidt

    2014-03-01

    Full Text Available With recent technological advances at synchrotrons [Graber et al., J. Synchrotron Radiat. 18, 658–670 (2011], it is feasible to rapidly collect time-resolved crystallographic data at multiple temperature settings [Schmidt et al., Acta Crystallogr. D 69, 2534–2542 (2013], from which barriers of activation can be extracted. With the advent of fourth generation X-ray sources, new opportunities emerge to investigate structure and dynamics of biological macromolecules in real time [M. Schmidt, Adv. Condens. Matter Phys. 2013, 1–10] in crystals and potentially from single molecules in random orientation in solution [Poon et al., Adv. Condens. Matter Phys. 2013, 750371]. Kinetic data from time-resolved experiments on short time-scales must be interpreted in terms of chemical kinetics [Steinfeld et al., Chemical Kinetics and Dynamics, 2nd ed. (Prentience Hall, 1985] and tied to existing time-resolved experiments on longer time-scales [Schmidt et al., Acta Crystallogr. D 69, 2534–2542 (2013; Jung et al., Nat. Chem. 5, 212–220 (2013]. With this article, we will review and outline steps that are required to routinely determine the energetics of reactions in biomolecules in crystal and solution with newest X-ray sources. In eight sections, we aim to describe concepts and experimental details that may help to inspire new approaches to collect and interpret these data.

  17. Vibrational algorithms for quantitative crystallographic analyses of hydroxyapatite-based biomaterials: II, application to decayed human teeth.

    Science.gov (United States)

    Adachi, Tetsuya; Pezzotti, Giuseppe; Yamamoto, Toshiro; Ichioka, Hiroaki; Boffelli, Marco; Zhu, Wenliang; Kanamura, Narisato

    2015-05-01

    A systematic investigation, based on highly spectrally resolved Raman spectroscopy, was undertaken to research the efficacy of vibrational assessments in locating chemical and crystallographic fingerprints for the characterization of dental caries and the early detection of non-cavitated carious lesions. Raman results published by other authors have indicated possible approaches for this method. However, they conspicuously lacked physical insight at the molecular scale and, thus, the rigor necessary to prove the efficacy of this spectroscopy method. After solving basic physical challenges in a companion paper, we apply them here in the form of newly developed Raman algorithms for practical dental research. Relevant differences in mineral crystallite (average) orientation and texture distribution were revealed for diseased enamel at different stages compared with healthy mineralized enamel. Clear spectroscopy features could be directly translated in terms of a rigorous and quantitative classification of crystallography and chemical characteristics of diseased enamel structures. The Raman procedure enabled us to trace back otherwise invisible characteristics in early caries, in the translucent zone (i.e., the advancing front of the disease) and in the body of lesion of cavitated caries.

  18. Crystallographic structure and substrate-binding interactions of the molybdate-binding protein of the phytopathogen Xanthomonas axonopodis pv. citri.

    Science.gov (United States)

    Balan, Andrea; Santacruz-Pérez, Carolina; Moutran, Alexandre; Ferreira, Luís Carlos Souza; Neshich, Goran; Gonçalves Barbosa, João Alexandre Ribeiro

    2008-02-01

    In Xanthomonas axonopodis pv. citri (Xac or X. citri), the modA gene codes for a periplasmic protein (ModA) that is capable of binding molybdate and tungstate as part of the ABC-type transporter required for the uptake of micronutrients. In this study, we report the crystallographic structure of the Xac ModA protein with bound molybdate. The Xac ModA structure is similar to orthologs with known three-dimensional structures and consists of two nearly symmetrical domains separated by a hinge region where the oxyanion-binding site lies. Phylogenetic analysis of different ModA orthologs based on sequence alignments revealed three groups of molybdate-binding proteins: bacterial phytopathogens, enterobacteria and soil bacteria. Even though the ModA orthologs are segregated into different groups, the ligand-binding hydrogen bonds are mostly conserved, except for Archaeglobus fulgidus ModA. A detailed discussion of hydrophobic interactions in the active site is presented and two new residues, Ala38 and Ser151, are shown to be part of the ligand-binding pocket.

  19. Soliton assisted control of source to drain electron transport along natural channels - crystallographic axes - in two-dimensional triangular crystal lattices

    Science.gov (United States)

    Chetverikov, A. P.; Ebeling, W.; Velarde, M. G.

    2016-09-01

    We present computational evidence of the possibility of fast, supersonic or subsonic, nearly loss-free ballistic-like transport of electrons bound to lattice solitons (a form of electron surfing on acoustic waves) along crystallographic axes in two-dimensional anharmonic crystal lattices. First we study the structural changes a soliton creates in the lattice and the time lapse of recovery of the lattice. Then we study the behavior of one electron in the polarization field of one and two solitons with crossing pathways with suitably monitored delay. We show how an electron surfing on a lattice soliton may switch to surf on the second soliton and hence changing accordingly the direction of its path. Finally we discuss the possibility to control the way an excess electron proceeds from a source at a border of the lattice to a selected drain at another border by following appropriate straight pathways on crystallographic axes.

  20. Crystallographic parameters of magnetic Pr2Fe14-xCoxB-type alloys determined using anomalous x-ray diffraction with synchrotron radiation

    Science.gov (United States)

    Galego, E.; Serna, M. M.; Ramanathan, L. V.; Faria, R. N.

    2017-02-01

    Anomalous x-ray synchrotron diffraction was used to determine the crystallographic parameters of PrFeCoB-based magnetic alloys. The effect of cobalt concentration on the crystallographic parameters of the magnetically hard Pr2Fe14-xCoxB phase was studied. The results indicate that addition of cobalt has a marked effect on crystal structure. Variation of the c parameter decreased twice as much as the a parameter with increase in Co content. The positions of inequivalent atoms of the magnetically hard matrix phase ϕ in the Pr-based alloys were determined using Rietveld refinement. This permitted determination of the relative distance of each inequivalent atom from its nearest neighbors. Cobalt occupied the 16k2 site and Fe had a tendency to occupy the 8j2 sites located between the Kagomé layers.

  1. Beeping a Maximal Independent Set

    CERN Document Server

    Afek, Yehuda; Bar-Joseph, Ziv; Cornejo, Alejandro; Haeupler, Bernhard; Kuhn, Fabian

    2012-01-01

    We consider the problem of computing a maximal independent set (MIS) in an extremely harsh broadcast model that relies only on carrier sensing. The model consists of an anonymous broadcast network in which nodes have no knowledge about the topology of the network or even an upper bound on its size. Furthermore, it is assumed that an adversary chooses at which time slot each node wakes up. At each time slot a node can either beep, that is, emit a signal, or be silent. At a particular time slot, beeping nodes receive no feedback, while silent nodes can only differentiate between none of its neighbors beeping, or at least one of its neighbors beeping. We start by proving a lower bound that shows that in this model, it is not possible to locally converge to an MIS in sub-polynomial time. We then study four different relaxations of the model which allow us to circumvent the lower bound and find an MIS in polylogarithmic time. First, we show that if a polynomial upper bound on the network size is known, it is possi...

  2. Copper-based alloys, crystallographic and crystallochemical parameters of alloys in binary systems Cu-Me (Me=Co, Rh, Ir, Cu, Ag, Au, Ni, Pd, Pt)

    Energy Technology Data Exchange (ETDEWEB)

    Porobova, Svetlana, E-mail: porobova.sveta@yandex.ru; Loskutov, Oleg, E-mail: lom58@mail.ru [Tomsk State University of Architecture and Building, Russia, Tomsk, 2 Solyanaya sq, Tomsk, 634003 (Russian Federation); Markova, Tat’jana, E-mail: patriot-rf@mail.ru [Siberian State Industrial University. 42 Kirov St., Novokuznetsk, 654007 (Russian Federation); Klopotov, Vladimir, E-mail: vdklopotov@mail.ru [Research Tomsk Polytechnic University, 30 Lenin Ave., Tomsk, 634050 (Russian Federation); Klopotov, Anatoliy, E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, Russia, Tomsk, 2 Solyanaya sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36, Lenin Ave., Tomsk, 634050 (Russian Federation); Vlasov, Viktor, E-mail: vik@tsuab.ru [Tomsk State University of Architecture and Building, Russia, Tomsk, 2 Solyanaya sq, Tomsk, 634003 (Russian Federation); Research Tomsk Polytechnic University, 30 Lenin Ave., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The article presents the results of the analysis of phase equilibrium of ordered phases in binary systems based on copper Cu- Me (where Me - Co, Rh, Ir, Ag, Au, Ni, Pd, Pt) to find correlations of crystallochemical and crystallographic factors. It is established that the packing index in disordered solid solutions in binary systems based on copper is close to the value of 0.74 against the background of an insignificant deviation of atomic volumes from the Zen’s law.

  3. Synthesis and crystallographic analysis of meso-2,3-difluoro-1,4-butanediol and meso-1,4-dibenzyloxy-2,3-difluorobutane

    Directory of Open Access Journals (Sweden)

    Bruno Linclau

    2010-06-01

    Full Text Available A large-scale synthesis of meso-2,3-difluoro-1,4-butanediol in 5 steps from (Z-but-2-enediol is described. Crystallographic analysis of the diol and the corresponding benzyl ether reveals an anti conformation of the vicinal difluoride moiety. Monosilylation of the diol is high-yielding but all attempts to achieve chain extension through addition of alkyl Grignard and acetylide nucleophiles failed.

  4. A Precipitate-Strengthening Model Based on Crystallographic Anisotropy, Stress-Induced Orientation, and Dislocation of Stress-Aged Al-Cu-Mg Single Crystals

    Science.gov (United States)

    Guo, Xiaobin; Zhang, Yong; Zhang, Jin; Deng, Yunlai; Zhang, Xinming

    2017-10-01

    We investigate the relationship between inhomogeneously distributed S precipitates and hardness of stress-aged single-crystal Al-Cu-Mg. First, the effect of crystallographic anisotropy is considered and modeled from the results of free-stress aged single-crystal Al-1.2Cu-0.5Mg with ( 1\\bar{1}8 ), ( \\bar{1}\\bar{2}5 ), (356), and (319) plane orientations. Effect of crystallographic anisotropy depends on the angle between the plane orientation of the single crystal and {012} habit planes of the S precipitates. Second, the effects of the magnitude of the applied stress and direction on the S-laths' size and distribution are considered. As the applied stress-induced S-laths inhomogeneously distribute during aging, the effect of the single-crystal's orientation on the distribution of S-laths is modeled. The results show that a single crystal near (111) plane orientation has the lowest stress-orienting effect. Finally, at higher applied stresses, such as 50 MPa, the S precipitates disperse more homogeneously due to the influence of the dislocations. Inhibiting the effect of dislocation depends on the angle between the plane orientation of the single crystal and the {111} dislocation slide planes. A precipitate-strengthening model of the stress-aged Al-Cu-Mg alloys is established based on crystallographic anisotropy, stress-orienting precipitates, and inhibiting the effect of dislocations.

  5. Study of the crystallographic architecture of corals at the nanoscale by scanning transmission X-ray microscopy and transmission electron microscopy.

    Science.gov (United States)

    Benzerara, Karim; Menguy, Nicolas; Obst, Martin; Stolarski, Jarosław; Mazur, Maciej; Tylisczak, Tolek; Brown, Gordon E; Meibom, Anders

    2011-07-01

    We have investigated the nanotexture and crystallographic orientation of aragonite in a coral skeleton using synchrotron-based scanning transmission X-ray microscopy (STXM) and transmission electron microscopy (TEM). Polarization-dependent STXM imaging at 40-nm spatial resolution was used to obtain an orientation map of the c-axis of aragonite on a focused ion beam milled ultrathin section of a Porites coral. This imaging showed that one of the basic units of coral skeletons, referred to as the center of calcification (COC), consists of a cluster of 100-nm aragonite globules crystallographically aligned over several micrometers with a fan-like distribution and with the properties of single crystals at the mesoscale. The remainder of the skeleton consists of aragonite single-crystal fibers in crystallographic continuity with the nanoglobules comprising the COC. Our observation provides information on the nm-scale processes that led to biomineral formation in this sample. Importantly, the present study illustrates how the methodology described here, which combines HRTEM and polarization-dependent synchrotron-based STXM imaging, offers an interesting new approach for investigating biomineralizing systems at the nm-scale.

  6. Path dependence and independent utility regulation

    DEFF Research Database (Denmark)

    Ibsen, Christian Lyhne; Skovgaard Poulsen, Lauge

    2007-01-01

    The establishment of the Danish independent regulatory authorities for the energy and telecommunications sectors was based upon EU directives as part of their liberalisation process. Following the concepts of transaction costs and path dependency this article analyses differences in independence...

  7. Outer-2-independent domination in graphs

    Indian Academy of Sciences (India)

    Marcin Krzywkowski; Doost Ali Mojdeh; Maryem Raoofi

    2016-02-01

    We initiate the study of outer-2-independent domination in graphs. An outer-2-independent dominating set of a graph is a set of vertices of such that every vertex of ()\\ has a neighbor in and the maximum vertex degree of the subgraph induced by ()\\ is at most one. The outer-2-independent domination number of a graph is the minimum cardinality of an outer-2-independent dominating set of . We show that if a graph has minimum degree at least two, then its outer-2-independent domination number equals the number of vertices minus the 2-independence number. Then we investigate the outer-2-independent domination in graphs with minimum degree one. We also prove the Vizing-type conjecture for outer-2-independent domination and disprove the Vizing-type conjecture for outer-connected domination.

  8. Legal and actual central bank independence

    OpenAIRE

    Artha, I.K.D.S.; de Haan, J.

    2010-01-01

    Indicators of central bank independence (CBI) based on the interpretation central bank laws in place may not capture the actual independence of the central bank. This paper develops an indicator of actual independence of the Bank Indonesia (BI), the central bank of Indonesia, for the period 1953-2008 and compares it with a new legal CBI indicator based on Cukierman (1992). The indicator of actual independence captures institutional and economic factors that affect CBI. We find that before 199...

  9. Learning Dilemmas in Undergraduate Student Independent Essays

    Science.gov (United States)

    Wendt, Maria; Åse, Cecilia

    2015-01-01

    Essay-writing is generally viewed as the primary learning activity to foster independence and analytical thinking. In this article, we show that independent research projects do not necessarily lead to critical thinking. University-level education on conducting independent projects can, in several respects, counteract enhanced analytical skills.…

  10. Independent Local Political Parties in the Netherlands

    NARCIS (Netherlands)

    Voerman, G.; Boogers, M.

    2010-01-01

    In the last 15 years, the Netherlands has witnessed the enormous growth of independent local parties and of their electoral support. In order to assess the success of independent locals in the Netherlands, this paper explores how independent local parties distinguish themselves ideologically, organi

  11. Models for Copper Dynamic Behavior in Doped Cadmium dl-Histidine Crystals: Electron Paramagnetic Resonance and Crystallographic Analysis.

    Science.gov (United States)

    Colaneri, Michael J; Teat, Simon J; Vitali, Jacqueline

    2015-11-12

    Electron paramagnetic resonance and crystallographic studies of copper-doped cadmium dl-histidine, abbreviated as CdDLHis, were undertaken to gain further understanding on the relationship between site structure and dynamic behavior in biological model complexes. X-ray diffraction measurements determined the crystal structure of CdDLHis at 100 and 298 K. CdDLHis crystallizes in the monoclinic space group P21/c with two cadmium complexes per asymmetric unit. In each complex, the Cd is hexacoordinated to two histidine molecules. Both histidines are l in one complex and d in the other. Additionally, each complex contains multiple waters of varying disorder. Single crystal EPR spectroscopic splitting (g) and copper hyperfine (A(Cu)) tensors at room temperature (principal values: g = 2.249, 2.089, 2.050; A(Cu) = -453, -30.5, -0.08 MHz) were determined from rotational experiments. Alignments of the tensor directions with the host structure were used to position the copper unpaired dx(2)-y(2) orbital in an approximate plane made by four proposed ligand atoms: the N-imidazole and N-amino of one histidine, and the N-amino and O-carboxyl of the other. Each complex has two such planes related by noncrystallographic symmetry, which make an angle of 65° and have a 1.56 Å distance between their midpoints. These findings are consistent with three interpretations that can adequately explain previous temperature-dependent EPR powder spectra of this system: (1) a local structural distortion (static strain) at the copper site has a temperature dependence significant enough to affect the EPR pattern, (2) the copper can hop between the two sites in each complex at high temperature, and (3) there exists a dynamic Jahn-Teller effect involving the copper ligands.

  12. Crystallographic structure of the human leukocyte antigen DRA, DRB3*0101: models of a directional alloimmune response and autoimmunity.

    Science.gov (United States)

    Parry, Christian S; Gorski, Jack; Stern, Lawrence J

    2007-08-10

    We describe structural studies of the human leukocyte antigen DR52a, HLA-DRA/DRB3*0101, in complex with an N-terminal human platelet integrin alphaII(B)betaIII glycoprotein peptide which contains a Leu/Pro dimorphism. The 33:Leu dimorphism is the epitope for the T cell directed response in neonatal alloimmune thrombocytopenia and post-transfusion purpura in individuals with the alphaII(B)betaIII 33:Pro allele, and defines the unidirectional alloimmune response. This condition is always associated with DR52a. The crystallographic structure has been refined to 2.25 A. There are two alphabeta heterodimers to the asymmetric unit in space group P4(1)2(1)2. The molecule is characterized by two prominent hydrophobic pockets at either end of the peptide binding cleft and a deep, narrower and highly charged P4 opening underneath the beta 1 chain. Further, the peptide in the second molecule displays a sharp upward turn after pocket P9. The structure reveals the role of pockets and the distinctive basic P4 pocket, shared by DR52a and DR3, in selecting their respective binding peptide repertoire. We observe an interesting switch in a residue from the canonically assigned pocket 6 seen in prior class II structures to pocket 4. This occludes the P6 pocket helping to explain the distinctive "1-4-9" peptide binding motif. A beta57 Asp-->Val substitution abrogates the salt-bridge to alpha76 Arg and along with a hydrophobic beta37 is important in shaping the P9 pocket. DRB3*0101 and DRB1*0301 belong to an ancestral haplotype and are associated with many autoimmune diseases linked to antigen presentation, but whereas DR3 is susceptible to type 1 diabetes DR52a is not. This dichotomy is explored for clues to the disease.

  13. Crystallographic Structure of the Human Leukocyte Antigen DRA, DRB3*0101: Models of a Directional Alloimmune Respone and Autoimmunity

    Energy Technology Data Exchange (ETDEWEB)

    Parry,C.; Gorski, J.; Stern, L.

    2007-01-01

    We describe structural studies of the human leukocyte antigen DR52a, HLA-DRA/DRB3*0101, in complex with an N-terminal human platelet integrin {alpha}II{sub B}{beta}III glycoprotein peptide which contains a Leu/Pro dimorphism. The 33:Leu dimorphism is the epitope for the T cell directed response in neonatal alloimmune thrombocytopenia and post-transfusion purpura in individuals with the {alpha}II{sub B}{beta}III 33:Pro allele, and defines the unidirectional alloimmune response. This condition is always associated with DR52a. The crystallographic structure has been refined to 2.25 {angstrom}. There are two {alpha}{beta} heterodimers to the asymmetric unit in space group P4{sub 1}2{sub 1}2. The molecule is characterized by two prominent hydrophobic pockets at either end of the peptide binding cleft and a deep, narrower and highly charged P4 opening underneath the beta 1 chain. Further, the peptide in the second molecule displays a sharp upward turn after pocket P9. The structure reveals the role of pockets and the distinctive basic P4 pocket, shared by DR52a and DR3, in selecting their respective binding peptide repertoire. We observe an interesting switch in a residue from the canonically assigned pocket 6 seen in prior class II structures to pocket 4. This occludes the P6 pocket helping to explain the distinctive '1-4-9' peptide binding motif. A {beta}57 Asp {yields} Val substitution abrogates the salt-bridge to {alpha}76 Arg and along with a hydrophobic {beta}37 is important in shaping the P9 pocket. DRB3*0101 and DRB1*0301 belong to an ancestral haplotype and are associated with many autoimmune diseases linked to antigen presentation, but whereas DR3 is susceptible to type 1 diabetes DR52a is not. This dichotomy is explored for clues to the disease.

  14. Tuning of the magnetostrictive properties of cobalt ferrite by forced distribution of substituted divalent metal ions at different crystallographic sites

    Science.gov (United States)

    Anantharamaiah, P. N.; Joy, P. A.

    2017-03-01

    Comparative studies have been made to understand the role of different crystallographic site preferences of the substituted non-magnetic divalent metal ions in the magnetostrictive properties of cobalt ferrite, by substitution of Zn2+ and/or Mg2+ for Fe3+ in CoMgxFe2-xO4, CoZnxFe2-xO4, and CoMgx/2Znx/2Fe2-xO4 (0.0 ≤ x ≤ 0.2). Detailed Raman spectral and magnetic characterizations are made to extract the information on the tetrahedral/octahedral site preferences of Zn and Mg in the spinel lattice of cobalt ferrite. The structural, microstructural, magnetic, Raman spectral, and magnetostrictive parameters of the studied compositions show distinguishable variations for x < 0.1 and x ≥ 0.1. Co-substitution of a small amount of Mg and Zn for Fe in CoMgx/2Znx/2Fe2-xO4 (x < 0.1) showed relatively larger strain sensitivity, [dλ/dH]max (-2.6 × 10-9 mA-1 for x = 0.05), higher than that for the Mg-substituted samples (-2.05 × 10-9 mA-1 for x = 0.05) and comparable to that for the Zn-substituted samples (-2.47 × 10-9 mA-1 for x = 0.05), without much drop in the maximum value of magnetostriction, λmax (-189 ppm for x = 0.05) compared to that for the unsubstituted counterpart (-221 ppm). The results show that it is possible to obtain high strain sensitivity (at fields <50 kA/m), along with high magnetostriction strain at low magnetic fields (˜250 kA/m), by tuning the distribution of the substituted cations in the tetrahedral and octahedral sites of the cobalt ferrite lattice.

  15. Microstructure and crystallographic preferred orientation of polycrystalline microgarnet aggregates developed during progressive creep, recovery, and grain boundary sliding

    Science.gov (United States)

    Massey, M.A.; Prior, D.J.; Moecher, D.P.

    2011-01-01

    Optical microscopy, electron probe microanalysis, and electron backscatter diffraction methods have been used to examine a broad range of garnet microstructures within a high strain zone that marks the western margin of a major transpression zone in the southern New England Appalachians. Garnet accommodated variable states of finite strain, expressed as low strain porphyroclasts (Type 1), high strain polycrystalline aggregates (Type 2), and transitional morphologies (Type 3) that range between these end members. Type 1 behaved as rigid porphyroclasts and is characterized by four concentric Ca growth zones. Type 2 help define foliation and lineation, are characterized by three Ca zones, and possess a consistent bulk crystallographic preferred orientation of (100) symmetrical to the tectonic fabric. Type 3 show variable degrees of porphyroclast associated with aggregate, where porphyroclasts display complex compositional zoning that corresponds to lattice distortion, low-angle boundaries, and subgrains, and aggregate CPO mimics porphyroclast orientation. All aggregates accommodated a significant proportion of greenschist facies deformation through grain boundary sliding, grain rotation and impingement, and pressure solution, which lead to a cohesive behavior and overall strain hardening of the aggregates. The characteristic CPO could not have been developed in this manner, and was the result of an older phase of partitioned amphibolite facies dislocation creep, recovery including chemical segregation, and recrystallization of porphyroclasts. This study demonstrates the significance of strain accommodation within garnet and its affect on composition under a range of PT conditions, and emphasizes the importance of utilizing EBSD methods with studies that rely upon a sound understanding of garnet. ?? 2010 Elsevier Ltd.

  16. Crystallographic and kinetic study of riboflavin synthase from Brucella abortus, a chemotherapeutic target with an enhanced intrinsic flexibility

    Energy Technology Data Exchange (ETDEWEB)

    Serer, María I.; Bonomi, Hernán R. [IIBBA–CONICET, Avenida Patricias Argentinas 435, C1405BWE Buenos Aires (Argentina); Guimarães, Beatriz G. [Synchrotron SOLEIL, L’Orme des Merisiers, Saint-Aubin BP 48, 91192 Gif-sur-Yvette CEDEX (France); Rossi, Rolando C. [Universidad de Buenos Aires, Junín 956, C1113AAD Buenos Aires (Argentina); Goldbaum, Fernando A.; Klinke, Sebastián, E-mail: sklinke@leloir.org.ar [IIBBA–CONICET, Avenida Patricias Argentinas 435, C1405BWE Buenos Aires (Argentina)

    2014-05-01

    This work reports crystal structures of trimeric riboflavin synthase from the pathogen B. abortus both as the apo protein and in complex with several ligands of interest. It is shown that ligand binding drives the assembly of the unique active site of the trimer, and these findings are complemented by a detailed kinetic study on this enzyme, in which marked inhibition by substrate and product was observed. Riboflavin synthase (RS) catalyzes the last step of riboflavin biosynthesis in microorganisms and plants, which corresponds to the dismutation of two molecules of 6,7-dimethyl-8-ribityllumazine to yield one molecule of riboflavin and one molecule of 5-amino-6-ribitylamino-2,4(1H,3H)-pyrimidinedione. Owing to the absence of this enzyme in animals and the fact that most pathogenic bacteria show a strict dependence on riboflavin biosynthesis, RS has been proposed as a potential target for antimicrobial drug development. Eubacterial, fungal and plant RSs assemble as homotrimers lacking C{sub 3} symmetry. Each monomer can bind two substrate molecules, yet there is only one active site for the whole enzyme, which is located at the interface between two neighbouring chains. This work reports the crystallographic structure of RS from the pathogenic bacterium Brucella abortus (the aetiological agent of the disease brucellosis) in its apo form, in complex with riboflavin and in complex with two different product analogues, being the first time that the structure of an intact RS trimer with bound ligands has been solved. These crystal models support the hypothesis of enhanced flexibility in the particle and also highlight the role of the ligands in assembling the unique active site. Kinetic and binding studies were also performed to complement these findings. The structural and biochemical information generated may be useful for the rational design of novel RS inhibitors with antimicrobial activity.

  17. Crystallographic study of Glu58Ala RNase T1 x 2'-guanosine monophosphate at 1.9-A resolution.

    Science.gov (United States)

    Pletinckx, J; Steyaert, J; Zegers, I; Choe, H W; Heinemann, U; Wyns, L

    1994-02-22

    Glu58 is known to participate in phosphodiester transesterification catalyzed by the enzyme RNase T1. For Glu58 RNase T1, an altered mechanism has been proposed in which His40 replaces Glu58 as the base catalyst [Steyaert, J., Hallenga, K., Wyns, L., & Stanssens, P. (1990) Biochemistry 29, 9064-9072]. Glu58Ala Rnase T1 has been cocrystallized with guanosine 2'-monophosphate (2'-GMP). The crystals are of space group P2(1), with one molecule per asymmetric unit (a = 32.44 A, b = 49.64 A, c = 26.09 A, beta = 99.17 degrees). The three-dimensional structure of the enzyme was determined to a nominal resolution of 1.9 A, yielding a crystallographic R factor of 0.178 for all X-ray data. Comparison of this structure with wild-type structures leads to the following conclusions. The minor changes apparent in the tertiary structure can be explained by either the mutation of Glu58 or by the change in the space group. In the active site, the extra space available through the mutation of Glu58 is occupied by the phosphate group (after a reorientation) and by a solvent molecule replacing a carboxylate oxygen of Glu58. This solvent molecule is a candidate for participation in the altered mechanism of this mutant enzyme. Following up on a study of conserved water sites in RNase T1 crystallized in space group P2(1)2(1)2(1) [Malin, R., Zielenkiewicz, P., & Saenger, W. (1991) J. Mol. Biol. 266, 4848-4852], we investigated the hydration structure for four different packing modes of RNase T1.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Biosynthetic incorporation of telluromethionine into dihydrofolate reductase and crystallographic analysis of the distribution of tellurium atoms in the protein molecule

    Energy Technology Data Exchange (ETDEWEB)

    Kunkle, M.G.; Lewinski, K.; Boles, J.O.; Dunlap, R.B.; Odom, J.D.; Lebioda, L. [Univ. of South Carolina, Columbia, SC (United States)

    1994-12-01

    Recent successes in crystallographic studies of proteins with methionine (Met) residues replaced with SeMet, pioneered by Hendrickson and coworkers, inspired us to replace Met with TeMet in Escherichia coli dihydrofolate reductase (DHFR). E. coli DHFR, which catalyzes the NADPH-dependent reduction of dihydrofolate to tetrahydrofolate, consists of 159 residues, 5 of which are Met. TeMet was incorporated into DHFR using the Met auxotroph, E. coli DL41, carrying the expression vector pWT8 with an IPTG inducible promoter and ampicillin resistance gene. The enzyme was purified by successive chromatography on Q-Sepharose and PHenyl Sepharose resins, yielding milligram quantities of homogeneous enzyme with a specific activity of 40 units/mg. TeMet DHFR exhibits kinetic properties similar to those of wt DHFR. Amino acid analysis indicated 3 authentic Met residues in TeMet DHFR, whereas atomic absorption spectroscopy detected 2 Te per protein molecule. Amino acid sequence analysis results suggested that only authentic Met was present in the first three Met positions (1,16,and 20). Crystals of Te-DHFR were grown in the presence of methotrexate from PEG 4000 and were isomorphous with wt-DHFR crystals grown from ethanol. Difference Fourier maps and restrained least-squares refinement show very little, if any, Te in the first three Met positions: Met{sup 1}, Met{sup 16}, and Met{sup 20}, whereas the occupancy of Te in positions 42 and 92 is 0.64. Apparently, the process of folding, subsequent purification, and crystallization select DHFR molecules with Te in Met{sup 42} and Met{sup 92}. Replacing Met with TeMet provides an internal probe that should facilitate structural and mechanistic studies of proteins.

  19. Recrystallization fabrics of sheared quartz veins with a strong pre-existing crystallographic preferred orientation from a seismogenic shear zone

    Science.gov (United States)

    Price, Nancy A.; Song, Won Joon; Johnson, Scott E.; Gerbi, Christopher C.; Beane, Rachel J.; West, David P.

    2016-07-01

    Microstructural investigations were carried out on quartz veins in schist, protomylonite, and mylonite samples from an ancient seismogenic strike-slip shear zone (Sandhill Corner shear zone, Norumbega fault system, Maine, USA). We interpret complexities in the microstructural record to show that: (1) pre-existing crystallographic preferred orientations (CPO) in the host rock may persist in the new CPO patterns of the shear zone and (2) the inner and outer parts of the shear zone followed diverging paths of fabric development. The host rocks bounding the shear zone contain asymmetrically-folded quartz veins with a strong CPO. These veins are increasingly deformed and recrystallized with proximity to the shear zone core. Matrix-accommodated rotation and recrystallization may position an inherited c-axis maximum in an orientation coincident with rhomb or basal slip. This inherited CPO likely persists in the shear zone fabric as a higher concentration of poles in one hemisphere of the c-axis pole figure, leading to asymmetric crossed girdle or paired maxima c-axis patterns about the foliation plane. Three observed quartz grain types indicate a general trend of localization with decreasing temperature: (1) large (> 100 μm), low aspect ratio (<~5) and (2) high aspect ratio (~ 5-20) grains overprinted by (3) smaller (<~80 μm), low aspect ratio (<~4) grains through subgrain rotation-dominated recrystallization. In the outer shear zone, subgrain rotation recrystallization led to a well-developed c-axis crossed girdle pattern. In the inner shear zone, the larger grains are completely overprinted by smaller grains, but the CPO patterns are relatively poorly developed and are associated with distinctively different misorientation angle histogram profiles ("flat" neighbor-pair profile with similar number fraction for angles from 10 to 90°). This may reflect the preferential activation of grain size sensitive deformation processes in the inner-most part of the shear zone

  20. Crystallization and preliminary crystallographic analysis of GanB, a GH42 intracellular β-galactosidase from Geobacillus stearothermophilus.

    Science.gov (United States)

    Solomon, Hodaya V; Tabachnikov, Orly; Feinberg, Hadar; Govada, Lata; Chayen, Naomi E; Shoham, Yuval; Shoham, Gil

    2013-10-01

    Geobacillus stearothermophilus T-6 is a Gram-positive thermophilic soil bacterium that contains a multi-enzyme system for the utilization of plant cell-wall polysaccharides, including xylan, arabinan and galactan. The bacterium uses a number of endo-acting extracellular enzymes that break down the high-molecular-weight polysaccharides into decorated oligosaccharides. These oligosaccharides enter the cell and are further hydrolyzed into sugar monomers by a set of intracellular glycoside hydrolases. One of these intracellular degrading enzymes is GanB, a glycoside hydrolase family 42 β-galactosidase capable of hydrolyzing short β-1,4-galactosaccharides to galactose. GanB and related enzymes therefore play an important part in the hemicellulolytic utilization system of many microorganisms which use plant biomass for growth. The interest in the biochemical characterization and structural analysis of these enzymes stems from their potential biotechnological applications. GanB from G. stearothermophilus T-6 has recently been cloned, overexpressed, purified, biochemically characterized and crystallized in our laboratory as part of its complete structure-function study. The best crystals obtained for this enzyme belong to the primitive orthorhombic space group P2₁2₁2₁, with average crystallographic unit-cell parameters of a=71.84, b=181.35, c=196.57 Å. Full diffraction data sets to 2.45 and 2.50 Å resolution have been collected for both the wild-type enzyme and its E323A nucleophile catalytic mutant, respectively, as measured from flash-cooled crystals at 100 K using synchrotron radiation. These data are currently being used for the full three-dimensional crystal structure determination of GanB.

  1. Low temperature and high pressure thermoelastic and crystallographic properties of SrZrO3 perovskite in the Pbnm phase

    Science.gov (United States)

    Knight, Kevin S.; Bull, Craig L.

    2016-12-01

    The thermoelastic and structural properties of SrZrO3 perovskite in the Pnma (Pbnm) phase have been studied using neutron powder diffraction at 82 temperatures between 11 K and 406 K at ambient pressure, and at sixteen pressures between 0.07 and 6.7 GPa at ambient temperature. The bulk modulus, derived by fitting the equation of state to a second order Birch-Murnaghan equation-of-state, 157(5) GPa, is in excellent agreement with that deduced in a recent resonant ultrasound investigation. Experimental axial compressional moduli are in agreement with those calculated from the elastic stiffness coefficients derived by ab-initio calculation, although the experimental bulk modulus is significantly softer than that calculated. Following low temperature saturation for temperatures less than 40 K, the unit cell monotonically increases with a predicted high temperature limit in the volume expansivity of ∼2.65 × 10-5 K-1. Axial linear thermal expansion coefficients are found to be in the order αb cell volume. Atomic displacement parameters have been fitted to a modified Debye model in which the zero-point term is an additional refinable variable and shows the cations and anions have well separated Debye temperatures, mirroring the need for two Debye-like distributions in the vibrational density of states. The temperature dependence of the crystal structure is presented in terms of the amplitudes of the seven symmetry-adapted basis vectors of the aristotype phase that are consistent with space group Pbnm, thus permitting a direct measure of the order parameter evolution in SrZrO3. The temperature variation of the in-phase tilt, which is lost at the phase transition at 973 K, is consistent with tricritical behaviour, in agreement with published results based on high temperature crystallographic data.

  2. Structural requirements of Na+-dependent antidopaminergic agents: Tropapride, Piquindone, Zetidoline, and Metoclopramide Comparison with Na+-independent ligands

    Science.gov (United States)

    Collin, Sonia; Vercauteren, Daniel P.; Vanderveken, Didier; Evrard, Guy; Durant, François

    1989-03-01

    Molecular graphic design coupled with PCILO and crystallographic results have been used to investigate the three-dimensional structure of Tropapride, Piquindone, Zetidoline, and Metoclopramide, four dopamine D-2 receptor antagonists showing Na+-dependent binding. Three putative pharmacophoric elements, a nitrogen lone pair, a phenyl ring and a carbonyl moiety, are similarly oriented in all the Na+-dependent drugs. Conversely, for Na+-independent analogs, the two latter pharmacophoric elements play a subordinate role, but two Π-electron regions are systematically localized on the other side of the molecule: the first is a phenyl group while the second is a carbonyl function as in butyrophenones, a cyano group as in R48455, or a phenyl ring as in diphenylbutylpiperidines or tricyclics. The presence of a benzyl ring on this side in Tropapride might explain its weak extrapyramidal effects.

  3. Crystal structure of dimethyl 2,5-bis-[(di-phen-oxy-phosphor-yl)-oxy]cyclo-hexa-1,4-diene-1,4-di-carboxyl-ate.

    Science.gov (United States)

    Gao, Lei; Ma, Zongshan; Yan, Hong

    2015-06-01

    In the title compound, C34H30O12P2, which was synthesized via the esterification of dimethyl 2,5-dioxo-1,4-cyclo-hexa-nedi-carboxyl-ate with diphenyl chloro-phosphate, the mol-ecule has crystallographic inversion symmetry. The dihedral angles between the plane of the cyclo-hexa-1,4-diene ring and those of the two benzene rings of the substituent phosphate groups are 41.0 (1) and 89.5 (1)°, while that with the ester group is 3.1 (3)°. In the crystal, only weak inter-molecular C-H⋯O hydrogen bonds are present.

  4. Ethyl 6-methyl-2-sulfanyl-idene-4-[4-(trifluoro-meth-yl)phen-yl]-1,2,3,4-tetra-hydro-pyrimidine-5-carboxyl-ate.

    Science.gov (United States)

    Nayak, Susanta K; Venugopala, K N; Govender, Thavendran; Kruger, Hendrik G; Maguire, Glenn E M; Row, T N Guru

    2011-07-01

    The title compound, C(15)H(15)F(3)N(2)O(2)S, adopts a conformation with an intra-molecular C-H⋯π inter-action. The dihedral angles between the planes of the 4-(trifluoro-meth-yl)phenyl and ester groups with the plane of the six-membered tetra-hydro-pyrimidine ring are 81.8 (1) and 16.0 (1)°, respectively. In the crystal structure, inter-molecular N-H⋯S hydrogen bonds link pairs of mol-ecules into dimers and N-H⋯O inter-actions generate hydrogen-bonded mol-ecular chains along the crystallographic a axis.

  5. ([2.2.2]Cryptand-κ(6)O)potassium (η(4)-cyclo-octa-diene)bis-(η(2)-pyrene)cobaltate(1-) pentane hemisolvate.

    Science.gov (United States)

    Brennessel, William W; Ellis, John E

    2012-07-01

    The cation, anion, and solvent in the title compound, [K(C(18)H(36)N(2)O(6))][Co(C(8)H(12))(C(16)H(10))(2)]·0.5C(5)H(12), are well separated. The pentane solvent mol-ecules are found in channels along [100] and were modeled as disordered over crystallographic inversion centers. Using the mid-points of the coordinated olefins, the angle between the C(py)/C(py)-Co-C(py)/C(py) and the C(cod)/C(cod)-Co-C(cod)/C(cod) planes (py is pyrene and cod is cyclo-octa-diene) is 67.6 (2)°. Thus, the overall geometry of the coordination sphere around cobalt is best described as distorted tetra-hedral.

  6. catena-Poly[[[trans-diaqua-bis(pyridine-κN)cobalt(II)]-μ-(4-{N'-[1-(3-acetyl-4-methyl-1H-pyrazol-5-yl)ethyl-idene]hydrazino}benzoato-κO:N,N')-[bis-(pyridine-κN)cobalt(III)]-μ-(4-{N'-[1-(3-acetyl-4-methyl-1H-pyrazol-5-yl)ethyl-idene]hydrazino}benzoato-κN,N':O)]perchlorate 3.66-hydrate].

    Science.gov (United States)

    Penkova, Larysa; Azarkh, Mikhail P; Haukka, Matti; Meyer, Franc; Fritsky, Igor O

    2008-01-30

    The title compound, {[Co(2)(C(15)H(14)N(4)O(3))(2)(C(5)H(5)N)(4)(H(2)O)(2)]ClO(4)·3.66H(2)O}(n), is a one-dimensional coordination polymer, with both Co(II) and Co(III) centres in its structure. The ligand environment surrounding Co(III) is formed by two N,N-chelating pyrazole-containing ligands and two pyridine mol-ecules in axial positions. The high-spin Co(II) ions, situated at crystallographic centres of inversion, exhibit a distorted octa-hedral coordination mode. The ClO(4) (-) anion is linked to the polymer chain via hydrogen bonds. The chains are connected by hydrogen bonds to produce a three-dimensional structure.

  7. Dicaesium diaqua-bis-(methyl-ene-diphospho-nato-κO,O')cobaltate(II).

    Science.gov (United States)

    van Merwe, Kina; Visser, Hendrik G; Venter, Johan A

    2011-10-01

    The asymmetric unit of the title compound, Cs(2)[Co(CH(4)O(6)P(2))(2)(H(2)O)(2)], is comprised of one bidentate methyl-enediphospho-nate ligand and one water mol-ecule which are coordinated to the Co(II) atom, as well as a caesium counter-cation. The Co atom occupies a special position on a crystallographic inversion center. The caesium ion is octa-hedrally coordinated by six O atoms with Cs-O distances ranging from 3.119 (2) to 3.296 (2) Å. A three-dimensional network is formed through O-H⋯O hydrogen bonds.

  8. Crystallographic Lattice Boltzmann Method

    Science.gov (United States)

    Namburi, Manjusha; Krithivasan, Siddharth; Ansumali, Santosh

    2016-01-01

    Current approaches to Direct Numerical Simulation (DNS) are computationally quite expensive for most realistic scientific and engineering applications of Fluid Dynamics such as automobiles or atmospheric flows. The Lattice Boltzmann Method (LBM), with its simplified kinetic descriptions, has emerged as an important tool for simulating hydrodynamics. In a heterogeneous computing environment, it is often preferred due to its flexibility and better parallel scaling. However, direct simulation of realistic applications, without the use of turbulence models, remains a distant dream even with highly efficient methods such as LBM. In LBM, a fictitious lattice with suitable isotropy in the velocity space is considered to recover Navier-Stokes hydrodynamics in macroscopic limit. The same lattice is mapped onto a cartesian grid for spatial discretization of the kinetic equation. In this paper, we present an inverted argument of the LBM, by making spatial discretization as the central theme. We argue that the optimal spatial discretization for LBM is a Body Centered Cubic (BCC) arrangement of grid points. We illustrate an order-of-magnitude gain in efficiency for LBM and thus a significant progress towards feasibility of DNS for realistic flows. PMID:27251098

  9. Crystallographic structure solution

    Directory of Open Access Journals (Sweden)

    Millán, Claudia

    2015-04-01

    Full Text Available The three-dimensional view of molecules at the atomic level provided by X-ray crystallography is not only extremely informative but is also easily and intuitively understood by humans, who very much rely on their vision. However, unlike microscopy, this technique does not directly yield an image. The structural model cannot be directly calculated from the diffraction data, as only the intensities of scattered beams and not their phases are experimentally accessible. In order to obtain the 3-dimensional structure phases have to be obtained by either additional experimental or computational methods. This is known as the phase problem in crystallography. In this manuscript we provide an overview of major milestones along the quest for the lost phases.La cristalografía proporciona una visión tridimensional de las moléculas a un nivel de detalle atómico, que no sólo resulta muy informativa sino que además puede ser fácil e intuitivamente comprendida por seres tan predominantemente visuales como solemos ser los humanos. Sin embargo, al contrario que la microscopía, esta técnica no ofrece directamente una imagen y el modelo estructural no puede calcularse directamente a partir de los datos de difracción, ya que solamente las intensidades de los rayos difractados y no sus fases son accesibles a la medida experimental. Para determinar la estructura tridimensional las fases deben ser obtenidas por medio de métodos adicionales, bien experimentales o computacionales. Esto constituye el problema de la fase en cristalografía. En este artículo ofreceremos una visión general de los principales hitos en la búsqueda de las fases perdidas.

  10. Independent School Libraries Perspectives on excellence

    CERN Document Server

    HAND, DORCAS

    2010-01-01

    Independent School Libraries: Perspectives on Excellence offers readers insights into best practices in library services for school communities, using examples drawn from independent schools of various sizes, descriptions, and locations across the United States. Two overview essays introduce a statistical analysis of independent schools. Each of the remaining essays provides perspective on a different aspect of library practice, including staffing, advocacy, assessment, technology, collaboration, programs beyond the curriculum, intellectual freedom and privacy, budgeting, accreditation, disast

  11. Calibration and Propagation of Uncertainty for Independence

    Energy Technology Data Exchange (ETDEWEB)

    Holland, Troy Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Kress, Joel David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bhat, Kabekode Ghanasham [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-06-30

    This document reports on progress and methods for the calibration and uncertainty quantification of the Independence model developed at UT Austin. The Independence model is an advanced thermodynamic and process model framework for piperazine solutions as a high-performance CO2 capture solvent. Progress is presented in the framework of the CCSI standard basic data model inference framework. Recent work has largely focused on the thermodynamic submodels of Independence.

  12. Facilitating location independence with computerized conversation systems

    OpenAIRE

    E J Menasse Noble; J.; Adler

    1996-01-01

    Location independence for organizations is desirable if they wish to achieve a given spatial distribution in a regional development plan. An organization's interaction with its environment forms the basis of its daily work and takes the form of 'information links' composed of fundamental indivisible blocks called 'conversations'. To achieve location independence it is necessary for organizations to develop and maintain environment interactions independent of their location. Information techno...

  13. The Independence Case in Comparative Perspective

    OpenAIRE

    Lineira, Robert; Cetra, Daniel

    2015-01-01

    Scotland is not the only sub-state unit in Europe where relevant political actors make claims for independence. To generate insights on these independence demands, we compare the drivers, arguments and popular support for secession in Scotland, the Basque Country, Catalonia and Flanders. We argue that national identity, party politics and the economy are behind the independence requests, and the exact articulation of these elements varies from case to case. Currently, the most salient of thes...

  14. Effect of Process Variables on the Grain Size and Crystallographic Texture of Hot-Dip Galvanized Coatings

    Science.gov (United States)

    Kaboli, Shirin; McDermid, Joseph R.

    2014-08-01

    A galvanizing simulator was used to determine the effect of galvanizing bath antimony (Sb) content, substrate surface roughness, and cooling rate on the microstructural development of metallic zinc coatings. Substrate surface roughness was varied through the use of relatively rough hot-rolled and relatively smooth bright-rolled steels, cooling rates were varied from 0.1 to 10 K/s, and bulk bath Sb levels were varied from 0 to 0.1 wt pct. In general, it was found that increasing bath Sb content resulted in coatings with a larger grain size and strongly promoted the development of coatings with the close-packed {0002} basal plane parallel to the substrate surface. Increasing substrate surface roughness tended to decrease the coating grain size and promoted a more random coating crystallographic texture, except in the case of the highest Sb content bath (0.1 wt pct Sb), where substrate roughness had no significant effect on grain size except at higher cooling rates (10 K/s). Increased cooling rates tended to decrease the coating grain size and promote the {0002} basal orientation. Calculations showed that increasing the bath Sb content from 0 to 0.1 wt pct Sb increased the dendrite tip growth velocity from 0.06 to 0.11 cm/s by decreasing the solid-liquid interface surface energy from 0.77 to 0.45 J/m2. Increased dendrite tip velocity only partially explains the formation of larger zinc grains at higher Sb levels. It was also found that the classic nucleation theory cannot completely explain the present experimental observations, particularly the effect of increasing the bath Sb, where the classical theory predicts increased nucleation and a finer grain size. In this case, the "poisoning" theory of nucleation sites by segregated Sb may provide a partial explanation. However, any analysis is greatly hampered by the lack of fundamental thermodynamic information such as partition coefficients and surface energies and by a lack of fundamental structural studies. Overall

  15. Kinetic, spectroscopic, and X-ray crystallographic characterization of the functional E151H aminopeptidase from Aeromonas proteolytica.

    Science.gov (United States)

    Bzymek, Krzysztof P; Moulin, Aaron; Swierczek, Sabina I; Ringe, Dagmar; Petsko, Gregory A; Bennett, Brian; Holz, Richard C

    2005-09-13

    Glutamate151 (E151) has been shown to be catalytically essential for the aminopeptidase from Vibrio proteolyticus (AAP). E151 acts as the general acid/base during the catalytic mechanism of peptide hydrolysis. However, a glutamate residue is not the only residue capable of functioning as a general acid/base during catalysis for dinuclear metallohydrolases. Recent crystallographic characterization of the D-aminopeptidase from Bacillus subtilis (DppA) revealed a histidine residue that resides in an identical position to E151 in AAP. Because the active-site ligands for DppA and AAP are identical, AAP has been used as a model enzyme to understand the mechanistic role of H115 in DppA. Substitution of E151 with histidine resulted in an active AAP enzyme exhibiting a kcat value of 2.0 min(-1), which is over 2000 times slower than r AAP (4380 min(-1)). ITC experiments revealed that ZnII binds 330 and 3 times more weakly to E151H-AAP compared to r-AAP. UV-vis and EPR spectra of CoII-loaded E151H-AAP indicated that the first metal ion resides in a hexacoordinate/pentacoordinate equilibrium environment, whereas the second metal ion is six-coordinate. pH dependence of the kinetic parameters kcat and K(m) for the hydrolysis of L-leucine p-nitroanilide (L-pNA) revealed a change in an ionization constant in the enzyme-substrate complex from 5.3 in r-AAP to 6.4 in E151H-AAP, consistent with E151 in AAP being the active-site general acid/base. Proton inventory studies at pH 8.50 indicate the transfer of one proton in the rate-limiting step of the reaction. Moreover, the X-ray crystal structure of [ZnZn(E151H-AAP)] has been solved to 1.9 A resolution, and alteration of E151 to histidine does not introduce any major conformational changes to the overall protein structure or the dinuclear ZnII active site. Therefore, a histidine residue can function as the general acid/base in hydrolysis reactions of peptides and, through analogy of the role of E151 in AAP, H115 in DppA likely

  16. Clathrin-independent endocytosis: mechanisms and function

    DEFF Research Database (Denmark)

    Sandvig, Kirsten; Pust, Sascha; Skotland, Tore

    2011-01-01

    a large fraction of the clathrin-independent uptake is dynamin-independent. Today, two decades later, the field has developed considerably. New techniques have enabled a detailed analysis of several clathrin-independent endocytic mechanisms, and caveolae have been found to be mostly stable structures...... having several functions of their own. This article aims at providing a brief update on the importance of clathrin-independent endocytic mechanisms, how the processes are regulated differentially, for instance on the poles of polarized cells, and the challenges in studying them....

  17. Does Auditor Rotation Increase Auditor Independence?

    Directory of Open Access Journals (Sweden)

    Junaidi Junaidi

    2016-12-01

    Full Text Available This study aims to empirically test the effects of auditor rotation and auditor tenure on an auditor’s independence in companies listed on the Indonesia Stock Exchange during the years 2002-2010. This study using logistic regression estimation technique. The results show that, statistically, the auditor’s tenure has significant negative effects on the auditor’s independence, measured by the tendency to give a ‘going concern’ opinion. Furthermore, the results also show significant differences between the effects of short and long term tenures on the auditors’ independence. Auditor rotation has significant positive effects on the auditors’ independence.

  18. Al-doped ZnO seed layer-dependent crystallographic control of ZnO nanorods by using electrochemical deposition

    Energy Technology Data Exchange (ETDEWEB)

    Son, Hyo-Soo; Choi, Nak-Jung [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of); Kim, Kyoung-Bo [Department of Metallurgical and Materials Engineering, Inha Technical College, Incheon 402-752 (Korea, Republic of); Kim, Moojin [Department of Renewable Energy, Jungwon University, Goesan-gun, Chungbuk 367-805 (Korea, Republic of); Lee, Sung-Nam, E-mail: snlee@kpu.ac.kr [Department of Nano-Optical Engineering, Korea Polytechnic University, Siheung 429-793 (Korea, Republic of)

    2016-10-15

    Highlights: • Polar and semipolar ZnO NRs were successfully achieved by hydrothermal synthesis. • Semipolar and polar ZnO NRs were grown on ZnO and AZO/m-sapphire, respectively. • Al % of AZO/m-sapphire enhanced the lateral growth rate of polar ZnO NRs. - Abstract: We investigated the effect of an Al-doped ZnO film on the crystallographic direction of ZnO nanorods (NRs) using electrochemical deposition. From high-solution X-ray diffraction measurements, the crystallographic plane of ZnO NRs grown on (1 0 0) ZnO/m-plane sapphire was (1 0 1). The surface grain size of the (100) Al-doped ZnO (AZO) film decreased with increasing Al content in the ZnO seed layer, implying that the Al dopant accelerated the three-dimensional (3D) growth of the AZO film. In addition, it was found that with increasing Al doping concentration of the AZO seed layer, the crystal orientation of the ZnO NRs grown on the AZO seed layer changed from [1 0 1] to [0 0 1]. With increasing Al content of the nonpolar (1 0 0) AZO seed layer, the small surface grains with a few crystallographic planes of the AZO film changed from semipolar (1 0 1) ZnO NRs to polar (0 0 1) ZnO NRs due to the increase of the vertical [0 0 1] growth rate of the ZnO NRs owing to excellent electrical properties.

  19. Role of crystallographic anisotropy in the formation of surface layers of single NiTi crystals after ion-plasma alloying

    Energy Technology Data Exchange (ETDEWEB)

    Poletika, T. M., E-mail: poletm@ispms.tsc.ru; Girsova, S. L., E-mail: llm@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); Meisner, L. L., E-mail: girs@ispms.tsc.ru; Meisner, S. N., E-mail: msn@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Shulepov, I. A., E-mail: iashulepov@tpu.ru [National Research Tomsk Polytechnic University, Tomsk, 634050 (Russian Federation)

    2015-10-27

    The structure of the surface and near-surface layers of single crystals of NiTi, differently oriented relative to the direction of ion beam treatment was investigated. The role of the crystallographic orientation in formation of structure of surface layers after ion-plasma alloying was revealed. It was found that the orientation effects of selective sputtering and channeling determine the thickness of the oxide and amorphous layers, the depth of penetration of ions and impurities, the distribution of Ni with depth.

  20. Crystallographic analysis of the implanted TiNi monocrystal containing misoriented localized shear mesobands in its near-surface layer [001]{sub B2}

    Energy Technology Data Exchange (ETDEWEB)

    Meisner, L. L., E-mail: llm@ispms.tsc.ru; Meisner, S. N., E-mail: msn@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation); National Research Tomsk State University, Tomsk, 634050 (Russian Federation); Tverdokhlebova, A. V., E-mail: a@vtverd.ru; Poletika, T. M., E-mail: poletm@ispms.tsc.ru; Girsova, S. L., E-mail: girs@ispms.tsc.ru [Institute of Strength Physics and Materials Science SB RAS, Tomsk, 634055 (Russian Federation)

    2015-10-27

    The study was carried on for the implanted single TiNi crystal containing misoriented localized shear mesobands in its near-surface layer [001] B2. Due to the response of material to the Si ion implantation treatment of the single TiNi crystal, deformation mesobands would form in its near-surface layer. Specially designed software tools were employed for the treatment of experimental data obtained from X-ray and electron diffraction patterns. The 3D crystallographic orientations were calculated for the localized shear regions, which were displaced relative to one another and with respect to the original monocrystal orientation.

  1. Aqueous solubility study of salts of benzylamine derivatives and p-substituted benzoic acid derivatives using X-ray crystallographic analysis

    DEFF Research Database (Denmark)

    Parshad, Henrik; Frydenvang, Karla Andrea; Liljefors, Tommy

    2004-01-01

    than those reported for the corresponding salts of benzylamine (I). Thermal analysis indicated that the increased solubility was caused by reduced crystal lattice energy, which was most likely due to the reduced number of strong hydrogen bonds of the salt of (II) and (III). X-ray crystallographic...... analysis of p-hydroxybenzoic acid salt of (I), (II) and (III) suggested that the reduced number of hydrogen bonds caused the apparent higher solubility. Further analyses of seven salts of (I) were performed. It was not possible to identify any relationship between the number of hydrogen bonds...

  2. Design, synthesis, crystallographic studies, and preliminary biological appraisal of new substituted triazolo[4,3-b]pyridazin-8-amine derivatives as tankyrase inhibitors.

    Science.gov (United States)

    Liscio, Paride; Carotti, Andrea; Asciutti, Stefania; Karlberg, Tobias; Bellocchi, Daniele; Llacuna, Laura; Macchiarulo, Antonio; Aaronson, Stuart A; Schüler, Herwig; Pellicciari, Roberto; Camaioni, Emidio

    2014-03-27

    Searching for selective tankyrases (TNKSs) inhibitors, a new small series of 6,8-disubstituted triazolo[4,3-b]piridazines has been synthesized and characterized biologically. Structure-based optimization of the starting hit compound NNL (3) prompted us to the discovery of 4-(2-(6-methyl-[1,2,4]triazolo[4,3-b]pyridazin-8-ylamino)ethyl)phenol (12), a low nanomolar selective TNKSs inhibitor working as NAD isostere as ascertained by crystallographic analysis. Preliminary biological data candidate this new class of derivatives as a powerful pharmacological tools in the unraveling of TNKS implications in physiopathological conditions.

  3. 40-Godišnjica institucije Cambridge Crystallographic Data Centre posvećene pohranjivanju podataka o molekularnim i kristalnim strukturama -

    Directory of Open Access Journals (Sweden)

    Molčanov, K.

    2006-06-01

    Full Text Available The article is dedicated to 40th anniversary of The Cambridge Crystallographic Data Centre (CCDC, the world-known centre (http://www.ccdc.cam.ac.uk responsible for deposition and control of crystallographic data, including atomic coordinates that define the three-dimensional structures of organic molecules and metal complexes containing organic ligands. Cambride Structural Database (CSD, one among the first established electronic databases, nowadays is the most significant crystallographic database in the world. CSD has about 400,000 deposited structures. The use of the extensive database, which is growing rapidly, needs support of efficient and sophisticated software for searching, analysing and visualising structural data. The seminal role of CSD in the research related to crystallography, chemistry, material sciences, solid state physics and chemistry, life sciences, pharmacology, and in particular in drug design, has been documented in more than 1300 scientific papers. The important issues of CCDC are the accuracy of deposited data and development of software that enables a wide variety of applications. Such demanding project requires higly competent team of experts; thus the article brings into focus the scientific approach of the team based on the long tradition in crystallography, modelling and informatics. The article is not dedicated to 40th anniversary of the centre only, but it also reveals how Cambridge Structural Database can be used in the research and teaching. The use of electronic media and computer graphics makes “data mining" very efficient and useful but also esthetically appealing due to the molecular architecture. At the Rudjer Bošković Institute, Zagreb, Croatia there is The National Affiliated Centre of Cambridge Crystallographic Data Centre responsible for communication and dissemination of CSD in Croatia, Slovenia and Macedonia. The use of CSD is illustrated by two examples performed and published by the presenting

  4. Uniqueness of time-independent electromagnetic fields

    DEFF Research Database (Denmark)

    Karlsson, Per W.

    1974-01-01

    As a comment on a recent paper by Steele, a more general uniqueness theorem for time-independent fields is mentioned. ©1974 American Institute of Physics......As a comment on a recent paper by Steele, a more general uniqueness theorem for time-independent fields is mentioned. ©1974 American Institute of Physics...

  5. 12 CFR 323.5 - Appraiser independence.

    Science.gov (United States)

    2010-01-01

    ... appraiser, that appraiser must be independent of the lending, investment, and collection functions and not... appraisal are involved in the lending, investment, or collection functions of the regulated institution, the regulated institution shall take appropriate steps to ensure that the appraisers exercise independent...

  6. 38 CFR 21.76 - Independent living.

    Science.gov (United States)

    2010-07-01

    ...) VOCATIONAL REHABILITATION AND EDUCATION Vocational Rehabilitation and Employment Under 38 U.S.C. Chapter 31 Duration of Rehabilitation Programs § 21.76 Independent living. (a) General. A program of independent living services may be authorized to enable the veteran to: (1) Reach the goals of the program, and...

  7. Central bank independence and financial instability

    NARCIS (Netherlands)

    Klomp, J.G.; de Haan, J.

    2009-01-01

    It has been argued that central bank independence (CBI) may not only be beneficial for reaching the objective of price stability, but also for maintaining financial stability. Greater independence from external pressure implies that central banks are less politically constrained in acting to prevent

  8. Accounting for Independent Schools. Second Edition.

    Science.gov (United States)

    National Association of Independent Schools, Boston, MA.

    This is a thoroughly revised edition of the 1969 publication, "Accounting for Independent Schools," a guide that attempted to codify basic accounting principles and practices for specific application to independent schools. The focus of the second edition is more on refining practices than on initiating them, and more on extending the managerial…

  9. 48 CFR 3.103 - Independent pricing.

    Science.gov (United States)

    2010-10-01

    ... 48 Federal Acquisition Regulations System 1 2010-10-01 2010-10-01 false Independent pricing. 3.103 Section 3.103 Federal Acquisition Regulations System FEDERAL ACQUISITION REGULATION GENERAL IMPROPER BUSINESS PRACTICES AND PERSONAL CONFLICTS OF INTEREST Safeguards 3.103 Independent pricing....

  10. The New Marketing Handbook for Independent Schools.

    Science.gov (United States)

    Boarding Schools, Boston, MA.

    Planning coherent, relevant marketing strategies is crucial to the survival of independent education in the United States. This handbook was created for independent school marketers; principals; and development, publications, public relations, and admissions directors. It offers checklists, sidebars, callouts, and summaries that focus on…

  11. Independence, Odd Girth, and Average Degree

    DEFF Research Database (Denmark)

    Löwenstein, Christian; Pedersen, Anders Sune; Rautenbach, Dieter;

    2011-01-01

      We prove several tight lower bounds in terms of the order and the average degree for the independence number of graphs that are connected and/or satisfy some odd girth condition. Our main result is the extension of a lower bound for the independence number of triangle-free graphs of maximum...

  12. Does central bank independence still matter?

    NARCIS (Netherlands)

    de Haan, Jakob; Masciandaro, Donato; Quintyn, Marc

    2008-01-01

    This paper sets out background on the literature on central bank independence (CBI) and summarizes the contributions of the papers in this special issue. The clear impression is that the answer to the question "Does central bank independence still matter?" is affirmative. (C) 2008 Elsevier B.V. All

  13. Accounting for Independent Schools. Second Edition.

    Science.gov (United States)

    National Association of Independent Schools, Boston, MA.

    This is a thoroughly revised edition of the 1969 publication, "Accounting for Independent Schools," a guide that attempted to codify basic accounting principles and practices for specific application to independent schools. The focus of the second edition is more on refining practices than on initiating them, and more on extending the managerial…

  14. 29 CFR 785.30 - Independent training.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false Independent training. 785.30 Section 785.30 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR STATEMENTS OF GENERAL... Lectures, Meetings and Training Programs § 785.30 Independent training. Of course, if an employee on...

  15. Can Bohmian Mechanics Be Made Background Independent?

    CERN Document Server

    Vassallo, Antonio

    2015-01-01

    The paper presents an inquiry into the question regarding the compatibility of Bohmian mechanics, intended as a non-local theory of moving point-like particles, with background independence. This issue is worth being investigated because, if the Bohmian framework has to be of some help in developing new physics, it has to be compatible with the most well-established traits of modern physics, background independence being one of such traits. The paper highlights the fact that the notion of background independence in the context of spacetime physics is slippery and interpretation-laden. It is then suggested that the best-matching framework developed by Julian Barbour might provide a robust enough meaning of background independence. The structure of Bohmian dynamics is evaluated against this framework, reaching some intermediate results that speak in favor of the fact that Bohmian mechanics can be made background independent.

  16. Crystallographic and magnetic structure of the perovskite-type compound BaFeO2.5: unrivaled complexity in oxygen vacancy ordering.

    Science.gov (United States)

    Clemens, Oliver; Gröting, Melanie; Witte, Ralf; Perez-Mato, J Manuel; Loho, Christoph; Berry, Frank J; Kruk, Robert; Knight, Kevin S; Wright, Adrian J; Hahn, Horst; Slater, Peter R

    2014-06-16

    We report here on the characterization of the vacancy-ordered perovskite-type structure of BaFeO2.5 by means of combined Rietveld analysis of powder X-ray and neutron diffraction data. The compound crystallizes in the monoclinic space group P2(1)/c [a = 6.9753(1) Å, b = 11.7281(2) Å, c = 23.4507(4) Å, β = 98.813(1)°, and Z = 28] containing seven crystallographically different iron atoms. The coordination scheme is determined to be Ba7(FeO4/2)1(FeO3/2O1/1)3(FeO5/2)2(FeO6/2)1 = Ba7Fe([6])1Fe([5])2Fe([4])4O17.5 and is in agreement with the (57)Fe Mössbauer spectra and density functional theory based calculations. To our knowledge, the structure of BaFeO2.5 is the most complicated perovskite-type superstructure reported so far (largest primitive cell, number of ABX2.5 units per unit cell, and number of different crystallographic sites). The magnetic structure was determined from the powder neutron diffraction data and can be understood in terms of "G-type" antiferromagnetic ordering between connected iron-containing polyhedra, in agreement with field-sweep and zero-field-cooled/field-cooled measurements.

  17. Novel nerve-agent antidote design based on crystallographic and mass spectrometric analyses of tabun-conjugated acetylcholinesterase in complex with antidotes.

    Science.gov (United States)

    Ekström, F J; Astot, C; Pang, Y-P

    2007-09-01

    Organophosphorus compound-based nerve agents inhibit the essential enzyme acetylcholinesterase (AChE) causing acute toxicity and death. Clinical treatment of nerve-agent poisoning is to use oxime-based antidotes to reactivate the inhibited AChE. However, the nerve agent tabun is resistant to oximes. To design improved oximes, crystal structures of a tabun-conjugated AChE in complex with different oximes are needed to guide the structural modifications of known antidotes. However, this type of structure is extremely challenging to obtain because both deamidation of the tabun conjugate and reactivation of AChE occur during crystallographic experiments. Here we report, for the first time, the crystal structures of Ortho-7 and HLö-7 in complex with AChE that is conjugated to an intact tabun. These structures were determined by our new strategy of combining crystallographic and mass spectrometric analyses of AChE crystals. The results explain the relative reactivation potencies of the two oximes and offer insights into improving known medical antidotes.

  18. Crystallographic and magnetic structure in spinel system FeGa {sub x} Cr{sub 2-} {sub x} S{sub 4} by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Soon Son, Bae [Department of Physics, Kookmin University, Seoul 136-702 (Korea, Republic of); Jin Kim, Sam [Department of Physics, Kookmin University, Seoul 136-702 (Korea, Republic of); Shim, In-Bo [Department of Physics, Kookmin University, Seoul 136-702 (Korea, Republic of); Wha Lee, Bo [Department of Physics, Hankuk University of Foreign Studies, Yongin, Kyungki, 449-791 (Korea, Republic of); Sung Kim, Chul [Department of Physics, Kookmin University, Seoul 136-702 (Korea, Republic of)]. E-mail: cskim@phys.kookmin.ac.kr

    2006-09-15

    The samples of FeGa {sub x} Cr{sub 2-} {sub x} S{sub 4} (x=0.1, 0.3) were prepared by solid reaction method. The crystallographic structure and the magnetic properties of the obtained compounds were investigated by X-ray and neutron powder diffraction, vibrating sample magnetometer (VSM), and Moessbauer spectroscopy. The Cr ions occupy 16(d) site exclusively, while mixed spinel behaviors are developed with increase of Ga ions. Finally, it induces a large quadrupole splitting in octahedral (16d) sites. Neutron diffraction on FeGa {sub x} Cr{sub 2-} {sub x} S{sub 4} above 10 K shows that there is no crystallographic distortion and reveals antiferromagnetic ordering. The magnetic moment of Fe{sup 2+} (3.45 {mu} {sub B}) are found to be aligned antiparallel to Cr{sup 3+} (-2.89 {mu} {sub B}), in the sample x=0.1. Below the Neel temperature, magnetic peaks exist on the crystal diffraction peaks. It proves that spin structure of the same species are aligned parallel.

  19. Methods for Solving Highly Symmetric De Novo Designed Metalloproteins: Crystallographic Examination of a Novel Three-Stranded Coiled-Coil Structure Containing d-Amino Acids.

    Science.gov (United States)

    Ruckthong, L; Stuckey, J A; Pecoraro, V L

    2016-01-01

    The core objective of de novo metalloprotein design is to define metal-protein relationships that control the structure and function of metal centers by using simplified proteins. An essential requirement to achieve this goal is to obtain high resolution structural data using either NMR or crystallographic studies in order to evaluate successful design. X-ray crystal structures have proven that a four heptad repeat scaffold contained in the three-stranded coiled coil (3SCC), called CoilSer (CS), provides an excellent motif for modeling a three Cys binding environment capable of chelating metals into geometries that resemble heavy metal sites in metalloregulatory systems. However, new generations of more complicated designs that feature, for example, a d-amino acid or multiple metal ligand sites in the helical sequence require a more stable construct. In doing so, an extra heptad was introduced into the original CS sequence, yielding a GRAND-CoilSer (GRAND-CS) to retain the 3SCC folding. An apo-(GRAND-CSL12DLL16C)3 crystal structure, designed for Cd(II)S3 complexation, proved to be a well-folded parallel 3SCC. Because this structure is novel, protocols for crystallization, structural determination, and refinements of the apo-(GRAND-CSL12DLL16C)3 are described. This report should be generally useful for future crystallographic studies of related coiled-coil designs.

  20. Stimulus independence, social cognition and consciousness.

    Science.gov (United States)

    Smallwood, Jonathan

    2011-06-01

    Abstract A consensus emerging from neuroscience is that certain brain regions show activity correlated with stimulus independent (e.g. private) conscious thought and yet are also implicated in public social processes. The fact that systems supporting social processing also exhibit activity with no obvious perceptual referent, can be seen as support for the framework suggested by Graziano and Kerber (this volume) once it is recognized that the property of stimulus independence is also an important feature of consciousness. Understanding the social basis behind private stimulus independent thought, therefore, may provide an important assessment of the validity of the Graziano and Kerber hypothesis.

  1. 4-Chloro-N-(3-methyl-benzo-yl)benzene-sulfonamide monohydrate.

    Science.gov (United States)

    Suchetan, P A; Foro, Sabine; Gowda, B Thimme; Prakash, M Shet

    2012-01-01

    In the title compound, C(14)H(12)ClNO(3)S·H(2)O, the dihedral angle between the sulfonyl and benzoyl benzene rings is 84.4 (2)°. In the crystal, every water mol-ecule forms four hydrogen bonds with three different mol-ecules of 4-chloro-N-(3-methyl-benzo-yl)benzene-sulfonamide. One of the water H atoms forms a bifurcated hydrogen bond with both the sulfonyl and the carbonyl O atoms of the same mol-ecule. Mol-ecules are linked into layers in the ab plane through N-H⋯O and O-H⋯O hydrogen bonds.

  2. N,N-Bis(4-chloro-phenyl-sulfon-yl)succinamide dihydrate.

    Science.gov (United States)

    Purandara, H; Foro, Sabine; Gowda, B Thimme

    2012-07-01

    The asymmetric unit of the title compound, C(16)H(14)Cl(2)N(2)O(6)S(2)·2H(2)O, contains one half-mol-ecule of N,N-bis-(4-chloro-phenyl-sulfon-yl)succinamide, with a centre of symmetry at the mid-point of the central C-C bond, and one water mol-ecule. The succinamide mol-ecules are not directly connected via hydrogen bonds, but by hydrogen bonds via the water mol-ecules.

  3. NMFS Fishery-Independent Survey System (FINSS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Fishery Independent Survey System (FINSS) is a national system that characterizes NMFS ocean observation activities, stock and ecosystem data collections during...

  4. Energy Independent Agri-Business Outreach

    Energy Technology Data Exchange (ETDEWEB)

    Niday, Karen [Cortland County Business Development Corporation, Cortland, NY (United States)

    2011-01-30

    Establish and showcase energy independence at a small to medium scale farm by installing renewable energy equipment that will enable an agribusiness to survive using only energy that is generated onsite

  5. Independent Component Analysis Over Galois Fields

    CERN Document Server

    Yeredor, Arie

    2010-01-01

    We consider the framework of Independent Component Analysis (ICA) for the case where the independent sources and their linear mixtures all reside in a Galois field of prime order P. Similarities and differences from the classical ICA framework (over the Real field) are explored. We show that a necessary and sufficient identifiability condition is that none of the sources should have a Uniform distribution. We also show that pairwise independence of the mixtures implies their full mutual independence (namely a non-mixing condition) in the binary (P=2) and ternary (P=3) cases, but not necessarily in higher order (P>3) cases. We propose two different iterative separation (or identification) algorithms: One is based on sequential identification of the smallest-entropy linear combinations of the mixtures, and is shown to be equivariant with respect to the mixing matrix; The other is based on sequential minimization of the pairwise mutual information measures. We provide some basic performance analysis for the bina...

  6. Materialism, status consumption, and consumer independence.

    Science.gov (United States)

    Goldsmith, Ronald Earl; Clark, Ronald A

    2012-01-01

    Materialism influences many people. We focus on two aspects of this influence: reactions to prestige products and to the influence of others. A study of 187 U.S. student consumers shows that materialism is positively related to buying products that confer status. In contrast, materialism is negatively related to consumer independence, an enduring tendency to pay minimal attention to the prescribed norms of other consumers and to make product and brand decisions according to personal preferences. Consuming products for status is also negatively related to consumer independence. Moreover, the association between materialism and consumer independence is completely mediated by consuming for status. Materialism urges consumers to be status conscious so that they follow social norms in purchasing, but seeking status through goods is avoided by less materialistic, independent consumers. A second study (n = 258) also using student consumers confirmed these results.

  7. Salicylic acid-independent plant defence pathways

    OpenAIRE

    Pieterse, C.M.J.; Loon, L. C. Van

    1999-01-01

    Salicylic acid is an important signalling molecule involved in both locally and systemically induced disease resistance responses. Recent advances in our understanding of plant defence signalling have revealed that plants employ a network of signal transduction pathways, some of which are independent of salicylic acid. Evidence is emerging that jasmonic acid and ethylene play key roles in these salicylic acid-independent pathways. Cross-talk between the salicylic acid-dependent and the salicy...

  8. Superimposition of response-independent reinforcement

    OpenAIRE

    Burgess, I. S.; Wearden, J H

    1986-01-01

    Studies that have superimposed response-independent reinforcement (or reinforcers scheduled by contingencies placed on the absence of responding) upon conventional response-dependent schedules are reviewed. In general, providing alternative sources of reinforcement reduced response rates below the levels observed when alternative reinforcement was absent. However, response-rate elevation was sometimes found, particularly when rates of superimposed response-independent reinforcement were low. ...

  9. Gravity wave and model-independent axion

    CERN Document Server

    Kim, Jihn E

    2016-01-01

    In this short comment, we notice that the model-independent axion contribution to the graviton mass at just outside the Schwarzschild radius is completely negligible in GW150914. The model-independent axion contribution to the graviton mass at the order $10^{-22}\\,$eV might be possible for merger of black holes of mass of order $2\\times 10^{14}\\,$kg.

  10. Does Auditor Rotation Increase Auditor Independence?

    OpenAIRE

    Junaidi Junaidi; Jogiyanto Hartono; Eko Suwardi; Setiyono Miharjo; Bambang Hartadi

    2016-01-01

    This study aims to empirically test the effects of auditor rotation and auditor tenure on an auditor’s independence in companies listed on the Indonesia Stock Exchange during the years 2002-2010. This study using logistic regression estimation technique. The results show that, statistically, the auditor’s tenure has significant negative effects on the auditor’s independence, measured by the tendency to give a ‘going concern’ opinion. Furthermore, the results also show significant differences ...

  11. CPI:Great Success in Independent Innovation

    Institute of Scientific and Technical Information of China (English)

    Yang Yajie; Wang Cong; Yuan Chen

    2009-01-01

    @@ The main strategy and development direction of CPI is independent innovating,striding over key sectors,supporting to develop and leading the future.CPI is always insisting in the guiding principles of "combining imports with independent innovation" to promote the science and technology work,and encourage the leading and supporting role of science and technology towards production and business,project construction and development of CPI.

  12. Does Auditor Rotation Increase Auditor Independence?

    OpenAIRE

    Junaidi, Junaidi; Hartono, Jogiyanto; Suwardi, Eko; Miharjo, Setiyono; Hartadi, Bambang

    2016-01-01

    This study aims to empirically test the effects of auditor rotation and auditor tenure on an auditor’s independence in companies listed on the Indonesia Stock Exchange during the years 2002-2010. This study using logistic regression estimation technique. The results show that, statistically, the auditor’s tenure has significant negative effects on the auditor’s independence, measured by the tendency to give a ‘going concern’ opinion. Furthermore, the results also show significant differences ...

  13. On the k-independence required by linear probing and minwise independence

    DEFF Research Database (Denmark)

    Pǎtraşcu, Mihai; Thorup, Mikkel

    2016-01-01

    We show that linear probing requires 5-independent hash functions for expected constant-time performance, matching an upper bound of Pagh et al. [2009]. More precisely, we construct a random 4-independent hash function yielding expected logarithmic search time for certain keys. For (1 + ε......)-approximate minwise independence, we show that Ω(lg1 ε)-independent hash functions are required, matching an upper bound of Indyk [2001]. We also show that the very fast 2-independent multiply-shift scheme of Dietzfelbinger [1996] fails badly in both applications....

  14. Independence-friendly cylindric set algebras

    CERN Document Server

    Mann, Allen L

    2007-01-01

    Independence-friendly logic is a conservative extension of first-order logic that has the same expressive power as existential second-order logic. In her Ph.D. thesis, Dechesne introduces a variant of independence-friendly logic called IFG logic. We attempt to algebraize IFG logic in the same way that Boolean algebra is the algebra of propositional logic and cylindric algebra is the algebra of first-order logic. We define independence-friendly cylindric set algebras and prove two main results. First, every independence-friendly cylindric set algebra over a structure has an underlying Kleene algebra. Moreover, the class of such underlying Kleene algebras generates the variety of all Kleene algebras. Hence the equational theory of the class of Kleene algebras that underly an independence-friendly cylindric set algebra is finitely axiomatizable. Second, every one-dimensional independence-friendly cylindric set algebra over a structure has an underlying monadic Kleene algebra. However, the class of such underlyin...

  15. Crystal structures of two mononuclear complexes of terbium(III) nitrate with the tripodal alcohol 1,1,1-tris-(hy-droxy-meth-yl)propane.

    Science.gov (United States)

    Gregório, Thaiane; Giese, Siddhartha O K; Nunes, Giovana G; Soares, Jaísa F; Hughes, David L

    2017-02-01

    Two new mononuclear cationic complexes in which the Tb(III) ion is bis-chelated by the tripodal alcohol 1,1,1-tris-(hy-droxy-meth-yl)propane (H3L(Et), C6H14O3) were prepared from Tb(NO3)3·5H2O and had their crystal and mol-ecular structures solved by single-crystal X-ray diffraction analysis after data collection at 100 K. Both products were isolated in reasonable yields from the same reaction mixture by using different crystallization conditions. The higher-symmetry complex dinitratobis[1,1,1-tris-(hy-droxy-meth-yl)propane]-terbium(III) nitrate di-meth-oxy-ethane hemisolvate, [Tb(NO3)2(H3L(Et))2]NO3·0.5C4H10O2, 1, in which the lanthanide ion is 10-coordinate and adopts an s-bicapped square-anti-prismatic coordination geometry, contains two bidentate nitrate ions bound to the metal atom; another nitrate ion functions as a counter-ion and a half-mol-ecule of di-meth-oxy-ethane (completed by a crystallographic twofold rotation axis) is also present. In product aqua-nitratobis[1,1,1-tris-(hy-droxy-meth-yl)propane]-terbium(III) dinitrate, [Tb(NO3)(H3L(Et))2(H2O)](NO3)2, 2, one bidentate nitrate ion and one water mol-ecule are bound to the nine-coordinate terbium(III) centre, while two free nitrate ions contribute to charge balance outside the tricapped trigonal-prismatic coordination polyhedron. No free water mol-ecule was found in either of the crystal structures and, only in the case of 1, di-meth-oxy-ethane acts as a crystallizing solvent. In both mol-ecular structures, the two tripodal ligands are bent to one side of the coordination sphere, leaving room for the anionic and water ligands. In complex 2, the methyl group of one of the H3L(Et) ligands is disordered over two alternative orientations. Strong hydrogen bonds, both intra- and inter-molecular, are found in the crystal structures due to the number of different donor and acceptor groups present.

  16. Independent competition authorities in the EU

    Directory of Open Access Journals (Sweden)

    Johan W. van de Gronden

    2006-06-01

    Full Text Available In most Member States competition law powers have been granted to a more or less independent competition authority. The idea is that the application and enforcement of competition law should not be influenced by political and volatile considerations. However, some recent cases, most notably in the field of merger control, show that political considerations can creep into the decision-making process in competition law. In this paper we examine how the independence of the competition authorities in the United Kingdom, Germany, the Netherlands and the European Union vis-à-vis the political system has actually been regulated. We have not only looked at the independent position from the political sphere, but also at the internal design of the competition authority, i.e. how it is managed. It appears that none of the national legislators has opted for total independence. But the national competition authorities have been confronted with less political control than in the past. For the Commission, this is different, as the Commissioner for Competition does not act independently from other Commissioners, which causes an imbalance between the status of national competition authorities and the Commission. Therefore, it could be considered whether an advisory agency might be set up, having that task to issue recommendations in the field of European competition law.

  17. Controleum - an independently extensible control system

    DEFF Research Database (Denmark)

    Jensen, Martin Lykke Rytter

    2014-01-01

    While the extensibility of many software systems has been greatly improved during the past two decades, nontrivial control systems remain to be a category of software systems that are remarkably difficult for independent parties to extend. Support for independent extension is the ability...... be resolved automatically. Typical control system components are concerned with the way in which actuators are controlled. Combining mutually unaware control system components that share interest in the same actuators are likely to lead to complex conflicts, thus making control systems a particularly...... challenging kind of system to design for independent extension. This thesis presents two new software technologies that improve the extensibility of control systems: First, the concept of dynamic links is introduced and Decouplink – an implementation of dynamic links for Java - is presented. Dynamic links...

  18. The Scottish Independence Referendum and After

    Directory of Open Access Journals (Sweden)

    Michael Keating

    2015-04-01

    Full Text Available The Scottish independence referendum on 18 September 2014 produced an apparently decisive result, with 45 per cent for independence and 55 per cent against. Yet, it has not settled the constitutional issue. There was a huge public engagement in the campaign, which has left a legacy for Scottish and UK politics. Scotland has been reinforced as a political community. The losing Yes side has emerged in better shape and more optimistic, while the winners have struggled to formulate the better autonomy package they had promised. Public opinion continues to favour maximum devolution short of independence. Scotland is a case of the kind of spatial rescaling that is taking place more generally across Europe, as new forms of statehood and of sovereignty evolve. Scottish public opinion favours more self-government but no longer recognizes the traditional nation-state model presented in the referendum question.

  19. Independents add gas reserves, forego romance

    Energy Technology Data Exchange (ETDEWEB)

    Gill, D.

    1981-08-01

    Incentive pricing for low-permeability reservoirs and tax advantages for drilling them are 2 big reasons why more independents may start making a special effort to add gas reserves to their inventories. If so, it will be a change from past practices, which saw independents build up big gas positions by circumstance rather than by intention. There are always major refiners ready and willing to buy whole crude oil reservoirs from small producers, but purchasers willing to take gas fields in a single investment are few and far between. Lower-than-normal return on equity during the first 20 years, plus the heavy front-end cost of a frac necessary to produce the tight gas might dissuade independents from drilling tight gas sands, but those liabilities are offset by the higher price tight gas gets and the peculiar tax advantages of exploring for it that make a nice fit with the small operator's way of doing business.

  20. Crystallographic and magnetostriction properties of Fe and FeB-alloy thin films formed on MgO(100 single-crystal substrates

    Directory of Open Access Journals (Sweden)

    Ohtake M.

    2013-01-01

    Full Text Available Fe(100bcc single-crystal film, Fe-B amorphous film, and Fe-B film consisting of a mixture of epitaxial bcc(100 crystal and amorphous are prepared on MgO(100 single-crystal substrates. The influence of crystallographic property on the magnetostriction behavior under rotating magnetic fields is investigated. The output waveform of magnetostriction is sinusoidal for the amorphous film, whereas that of single-crystal film shows a triangle shape. 90° magnetic domain walls are observed for the single-crystal Fe film and the film shows a four-fold symmetry in in-plane magnetic anisotropy. The observation of triangle waveforms is related to the domain wall motion in magnetically unsaturated Fe(100bcc film under rotating magnetic fields. A distortion from triangle wave is observed for the Fe-B film consisting of a mixture of bcc-crystal and amorphous. The magnetostriction behavior is influenced by the magnetization structure.

  1. Influence of chemical composition in crystallographic texture Fe-Cr-Mo alloys; Influencia da composicao quimica na textura cristalografica de ligas Fe-Cr-Mo

    Energy Technology Data Exchange (ETDEWEB)

    Moura, L.B.; Guimaraes, R.F. [Instituto Federal de Educacao, Ciencia e Tecnologia do Ceara, Fortaleza, CE (Brazil). Dept. da Industria; Abreu, H.F.G. [Universidade Federal do Ceara (UFC), Fortaleza, CE (Brazil)

    2010-07-01

    The use of steels with higher contents of Mo in the oil industry has been an alternative to reduce the effect of naphthenic corrosion in refining units. The addition of Mo in Fe-Cr alloys in the same manner that increases resistance to corrosion naphthenic causes some difficulties such as difficulty of forming, welding and embrittlement. In this work, experimental ingots of Fe-Cr-Mo alloys (Cr - 9, 15 and 17%, Mo - 5, 7 and 9%) were melted in vacuum induction furnace and hot and cold rolled in a laboratory rolling mill. The influence of chemical composition on crystallographic texture of samples subjected to the same thermo-mechanical treatment was analyzed by x-ray diffraction. The results indicate that fiber (111) becomes more intense with increasing Mo and/or Cr contents. (author)

  2. Effect of PVC on ionic conductivity, crystallographic structural, morphological and thermal characterizations in PMMA-PVC blend-based polymer electrolytes

    Energy Technology Data Exchange (ETDEWEB)

    Ramesh, S., E-mail: rameshtsubra@gmail.com [Centre for Ionics University Malaya, Department of Physics, Faculty of Science, University of Malaya, Lembah Pantai, 50603 Kuala Lumpur (Malaysia); Liew, Chiam-Wen; Morris, Ezra; Durairaj, R. [Faculty of Engineering and Science, Universiti Tunku Abdul Rahman, Setapak, 53300 Kuala Lumpur (Malaysia)

    2010-11-20

    In this paper, temperature dependence of ionic conductivity, crystallographic structural, morphological and thermal characteristics of polymer blends of PMMA and PVC with lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) as a dopant salt are investigated. The study on the temperature dependence of ionic conductivity shows that these polymer blends exhibit Arrhenius behavior. The highest ionic conductivity was achieved when 70 wt% of PMMA was blended with 30 wt% of PVC. X-ray diffraction (XRD) and scanning electron microscopy (SEM) reveal the amorphous nature and surface morphology of polymer electrolytes, respectively. In DSC analysis it was found that the glass transition temperature (T{sub g}) and melting temperature (T{sub m}) decreased, whereas the decomposition temperature (T{sub d}) increased. In contrast, the shift towards higher decomposition temperature and decrease in weight loss of polymer electrolytes, in TGA studies, indicates that the thermal stability of polymer electrolytes improved.

  3. Microstructure and Crystallographic Texture Variations in the Friction-Stir-Welded Al-Al2O3-B4C Metal Matrix Composite Produced by Accumulative Roll Bonding

    Science.gov (United States)

    Mohammadnezhad, Mahyar; Shamanian, Morteza; Zabolian, Azam; Taheri, Mahshid; Javaheri, Vahid; Navidpour, Amir Hossein; Nezakat, Majid; Szpunar, Jerzy A.

    2015-12-01

    In this research, ultrafine-grained sheets of aluminum matrix composite (Al-Al2O3-B4C) were produced by accumulative roll bonding ARB technique. As-received, ultrafine-grained aluminum composite sheets were joined by friction-stir welding. The microstructure, crystallographic texture, and Vickers hardness in the weld zones were investigated. Electron backscattered diffraction results revealed occurrence of dynamic recrystallization and demonstrated existence of different grain orientations within the weld nugget. Produced composite plates illustrated rotated cubic texture. Moreover, in the nugget, a well-recrystallized grain structure having characteristic strong shear texture component finally developed. However, the texture result in the heat-affected zone illustrated rotated cubic and Goss components that related to the effect of heat input. Friction-stir welding refined the grain size in the weld zone. The hardness also improved with the peak hardness being observed towards the advancing stir welding side.

  4. Significance of Jane Eyre' s Independence

    Institute of Scientific and Technical Information of China (English)

    潘文涛

    2008-01-01

    Jane Eyre, by far the best known of Charlotte Bronte' s literary production, published 1847. Jane, the heroine, a governess's rebelliousness, her hate ot servility, her insistence on equality with her master, and her declaration that she has a right to feelings and passions that impresses me most. This paper, from what Jane Eyre experiences and what she thinks about the happenings, analyses Jane Eyreg independent characters and spirits in five segments each with its own setting: Gateshead, Lowood, Thnmfield, Moor House, Femdean, points out the significance of Jane Eyre's independence in her ages.

  5. On gauge-independence in quantum gravity

    CERN Document Server

    Vasilevich, D V

    1995-01-01

    We prove gauge-independence of one-loop path integral for on-shell quantum gravity obtained in a framework of modified geometric approach. We use projector on pure gauge directions constructed via quadratic form of the action. This enables us to formulate the proof entirely in terms of determinants of non-degenerate elliptic operators without reference to any renormalization procedure. The role of the conformal factor rotation in achieving gauge-independence is discussed. Direct computations on CP^2 in a general three-parameter background gauge are presented. We comment on gauge dependence of previous results by Ichinose.

  6. Survey of independent inventors: An overview

    Energy Technology Data Exchange (ETDEWEB)

    Whalley, P.

    1992-12-01

    Independent inventors are important but little-researched members of the US technical community. The survey reported on here is the first in modern times to attempt to provide a profile of the US independent inventor that goes beyond a single geographical or organizational locale. The report that follows provides an overview of the demographics, practices and concerns of the modern US inventor as represented by the members of leading US inventor organizations. It is by no means comprehensive but seeks to be indicative of the issues raised in the survey each which will be dealt with more comprehensively in future publications.

  7. THE RIGHT TO AN INDEPENDENT COURT

    Directory of Open Access Journals (Sweden)

    ALIN-GHEORGHE GAVRILESCU

    2011-04-01

    Full Text Available The independence of the court is essential of state of rule, to maintain the stability in juridical intercourse, for the existence of a constitutional democracy achieved through a warranty of the necessary objectivity for the steady and legal settlement of the causes deducted to the trial and the achievement of a fair trial. The article emphasizes the main international juridical tools in which independence of justice is reflected, achieving an examination of judicial practice of European instance as well as an analysis of this principle as it is regulated by Romanian justice.

  8. Becoming independent through au pair migration

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2015-01-01

    . This article argues that, despite this critique, au pairing does play an important formative role for young Filipinas because it opens up for experiences abroad that enable them to be recognised as independent adults in Philippine society. Rather than autonomy, however, au pairs define their independence...... in terms of their capacity to assume responsibility for others, thereby achieving a position of social respect. Based on ethnographic fieldwork in Denmark and the Philippines, this article explores how young Filipinas use the social, economic, and cultural resources they gain from their au pair stay abroad...

  9. Expression, limited proteolysis and preliminary crystallographic analysis of IpaD, a component of the Shigella flexneri type III secretion system

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, Steven [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Sir William Dunn School of Pathology, University of Oxford (United Kingdom); Roversi, Pietro [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Espina, Marianela [Department of Molecular Biosciences, University of Kansas (United States); Deane, Janet E. [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Birket, Susan; Picking, William D. [Department of Molecular Biosciences, University of Kansas (United States); Blocker, Ariel [Sir William Dunn School of Pathology, University of Oxford (United Kingdom); Picking, Wendy L. [Department of Molecular Biosciences, University of Kansas (United States); Lea, Susan M., E-mail: susan.lea@path.ox.ac.uk [Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford (United Kingdom); Sir William Dunn School of Pathology, University of Oxford (United Kingdom)

    2006-09-01

    IpaD, the putative needle-tip protein of the S. flexneri type III secretion system, has been crystallized in a variety of crystal forms using in-drop proteolysis. Native and selenomethionine-labelled data collection and preliminary analyses are reported. IpaD, the putative needle-tip protein of the Shigella flexneri type III secretion system, has been overexpressed and purified. Crystals were grown of the native protein in space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 55.9, b = 100.7, c = 112.0 Å, and data were collected to 2.9 Å resolution. Analysis of the native Patterson map revealed a peak at 50% of the origin on the Harker section v = 0.5, suggesting twofold non-crystallographic symmetry parallel to the b crystallographic axis. As attempts to derivatize or grow selenomethionine-labelled protein crystals failed, in-drop proteolysis was used to produce new crystal forms. A trace amount of subtilisin Carlsberg was added to IpaD before sparse-matrix screening, resulting in the production of several new crystal forms. This approach produced SeMet-labelled crystals and diffraction data were collected to 3.2 Å resolution. The SeMet crystals belong to space group C2, with unit-cell parameters a = 139.4, b = 45.0, c = 99.5 Å, β = 107.9°. An anomalous difference Patterson map revealed peaks on the Harker section v = 0, while the self-rotation function indicates the presence of a twofold noncrystallographic symmetry axis, which is consistent with two molecules per asymmetric unit.

  10. Cation distribution and crystallographic characterization of the spinel oxides MgCr{sub x}Fe{sub 2−x}O{sub 4} by neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Zakaria, A.K.M., E-mail: zakaria6403@yahoo.com [Institute of Nuclear Science & Technology, Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Nesa, Faizun [Department of Natural Science, Daffodil International University, Dhaka (Bangladesh); Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh); Saeed Khan, M.A. [Department of Physics, Jahangirnagar University, Savar, Dhaka (Bangladesh); Datta, T.K.; Aktar, Sanjida; Liba, Samia Islam; Hossain, Shahzad; Das, A.K.; Kamal, I.; Yunus, S.M. [Institute of Nuclear Science & Technology, Bangladesh Atomic Energy Commission, Dhaka (Bangladesh); Eriksson, S.-G. [Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg (Sweden)

    2015-06-05

    Highlights: • MgCr{sub x}Fe{sub 2−x}O{sub 4} ferrites crystallize at 1300 °C and possess cubic symmetry. • Cation distribution and crystallographic parameters have been determined precisely. • Cell parameter decreases with increasing Cr content in the system. • Ferrimagnetic ordering was found at room temperature for all the samples. - Abstract: The spinel system MgCr{sub x}Fe{sub 2−x}O{sub 4} (x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0) has been prepared by solid state sintering method in air at 1573 K. X-ray and neutron powder diffraction experiments have been performed on the samples at room temperature for structural characterization. Rietveld refinement of the neutron diffraction data reveals that all the samples of the series possess cubic symmetry corresponding to the space group F d-3m. The distribution of the three cations Mg, Fe and Cr over the two sublattices and other crystallographic parameters has been determined precisely. The results reveal that Cr has been substituted for Fe selectively. Cr ions invariably occupy the octahedral (B) site for all values of x. Mg and Fe ions are distributed over both A and B sites for all x values. With increasing x the occupation of Mg increases in the A site and decreases in the B site for all the samples, while the Fe ions gradually decreases in both the sites for all values of x. The lattice constant decreases with increasing Cr content in the system. The magnetic structure at room temperature was ferrimagnetic for all the samples.

  11. Crystallographic analysis of human hemoglobin elucidates the structural basis of the potent and dual antisickling activity of pyridyl derivatives of vanillin

    Energy Technology Data Exchange (ETDEWEB)

    Abdulmalik, Osheiza [The Children’s Hospital of Philadelphia, Philadelphia, PA 19104 (United States); Ghatge, Mohini S.; Musayev, Faik N.; Parikh, Apurvasena [Virginia Commonwealth University, Richmond, VA 23298 (United States); Chen, Qiukan; Yang, Jisheng [The Children’s Hospital of Philadelphia, Philadelphia, PA 19104 (United States); Nnamani, Ijeoma [Duke University Medical Center, Durham, NC 27710 (United States); Danso-Danquah, Richmond [Virginia Commonwealth University, Richmond, VA 23298 (United States); Eseonu, Dorothy N. [Virginia Union University, Richmond, VA 23220 (United States); Asakura, Toshio [Duke University Medical Center, Durham, NC 27710 (United States); Abraham, Donald J.; Venitz, Jurgen; Safo, Martin K., E-mail: msafo@vcu.edu [Virginia Commonwealth University, Richmond, VA 23298 (United States); The Children’s Hospital of Philadelphia, Philadelphia, PA 19104 (United States)

    2011-11-01

    Pyridyl derivatives of vanillin increase the fraction of the more soluble oxygenated sickle hemoglobin and/or directly increase the solubility of deoxygenated sickle hemoglobin. Crystallographic analysis reveals the structural basis of the potent and dual antisickling activity of these derivatives. Vanillin has previously been studied clinically as an antisickling agent to treat sickle-cell disease. In vitro investigations with pyridyl derivatives of vanillin, including INN-312 and INN-298, showed as much as a 90-fold increase in antisickling activity compared with vanillin. The compounds preferentially bind to and modify sickle hemoglobin (Hb S) to increase the affinity of Hb for oxygen. INN-312 also led to a considerable increase in the solubility of deoxygenated Hb S under completely deoxygenated conditions. Crystallographic studies of normal human Hb with INN-312 and INN-298 showed that the compounds form Schiff-base adducts with the N-terminus of the α-subunits to constrain the liganded (or relaxed-state) Hb conformation relative to the unliganded (or tense-state) Hb conformation. Interestingly, while INN-298 binds and directs its meta-positioned pyridine-methoxy moiety (relative to the aldehyde moiety) further down the central water cavity of the protein, that of INN-312, which is ortho to the aldehyde, extends towards the surface of the protein. These studies suggest that these compounds may act to prevent sickling of SS cells by increasing the fraction of the soluble high-affinity Hb S and/or by stereospecific inhibition of deoxygenated Hb S polymerization.

  12. Effect of crystallographic orientation in textured Ba0.92Ca0.08TiO3 piezoelectric ceramics

    Science.gov (United States)

    Haugen, Astri Bjørnetun; Morozov, Maxim I.; Johnsson, Mats; Grande, Tor; Einarsrud, Mari-Ann

    2014-10-01

    Strongly textured lead-free Ba0.92Ca0.08TiO3 piezoelectric ceramics were fabricated by tape casting and templated grain growth. Dense ceramics with both favorable ⟨100⟩ and unfavorable ⟨111⟩ texture were successfully prepared. Enhanced piezoelectric performance was demonstrated for ceramics with ⟨100⟩ texture, in line with the predictions based on reported piezoelectric coefficients of tetragonal BaTiO3. Due to the expanded tetragonal range through Ca-substitution, ⟨100⟩ texture is favorable over a wide temperature range. The ⟨100⟩ texture also results in the enhanced piezoelectric performance being temperature-independent. In addition to engineering of stable, high-performance lead-free piezoelectric ceramics, this study has demonstrated that consideration of the extender/rotator nature of piezoelectric properties is imperative for improving the piezoelectric response through texturing.

  13. Data-driven high-throughput prediction of the 3-D structure of small molecules: review and progress. A response to the letter by the Cambridge Crystallographic Data Centre.

    Science.gov (United States)

    Baldi, Pierre

    2011-12-27

    A response is presented to sentiments expressed in "Data-Driven High-Throughput Prediction of the 3-D Structure of Small Molecules: Review and Progress. A Response from The Cambridge Crystallographic Data Centre", recently published in the Journal of Chemical Information and Modeling, (1) which may give readers a misleading impression regarding significant impediments to scientific research posed by the CCDC.

  14. The Public Sphere and Online, Independent Journalism

    Science.gov (United States)

    Beers, David

    2006-01-01

    The rapid evolution of online, independent journalism affords educators an opportunity to increase students' understanding of the nature and power of the news media. Drawing from Habermas's theories of the role of the public sphere in democratic discourse, the author, as founder of an online news publication, traces trends in concentrated…

  15. The Next Marketing Handbook for Independent Schools.

    Science.gov (United States)

    Cowan, Rick, Ed.

    Suggestions for marketing independent schools are presented in this handbook, which revolves around the basic marketing model of defining mission/strategy, using the "5 P's" (product/services, price, place, production/delivery, promotion) and monitoring. Chapters by 18 contributors offer information on the following topics: basic marketing theory,…

  16. A Student Guide for Independent Study Telecourses.

    Science.gov (United States)

    Chavez, Mauro

    Designed for students enrolled in telecourses offered by Evergreen Valley College (EVC) on an independent study basis, this guide explains the role of telecourses in the college curriculum, differences and similarities between telecourses and traditional courses, procedures for contacting instructors, and the roles of the college and the student…

  17. Gandhi and Tagore: Two Paths to Independence.

    Science.gov (United States)

    Pilling, Anita

    This unit of study introduces high school students to the idea that people of integrity often disagree and still respect each others' efforts to achieve specific goals. The lessons examine the differences between Mahatma Gandhi and Rabindranath Tagore in the Indian struggle for independence from Great Britain and also looks at their views on…

  18. 12 CFR 34.45 - Appraiser independence.

    Science.gov (United States)

    2010-01-01

    ... staff appraiser, that appraiser must be independent of the lending, investment, and collection functions... perform an appraisal are involved in the lending, investment, or collection functions of the regulated institution, the regulated institution shall take appropriate steps to ensure that the appraisers exercise...

  19. Nonsalary Compensation for Employees of Independent Schools.

    Science.gov (United States)

    Miller, Ned A.

    A guide, intended to help independent schools attract and retain competent people through appropriate compensation packages, provides the basis for a review of a school's current general benefits program. It also contains suggestions for improving compensation packages by offering a wider range of tax-favored nonsalary benefits without necessarily…

  20. Independent Events in Elementary Probability Theory

    Science.gov (United States)

    Csenki, Attila

    2011-01-01

    In Probability and Statistics taught to mathematicians as a first introduction or to a non-mathematical audience, joint independence of events is introduced by requiring that the multiplication rule is satisfied. The following statement is usually tacitly assumed to hold (and, at best, intuitively motivated): If the n events E[subscript 1],…