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Sample records for nasicon type structure

  1. Structural investigations on scandium substituted nasicons

    International Nuclear Information System (INIS)

    Neutron diffraction data were used to refine the structures of three scandium substituted nasicons: Na2ZrSc(PO4)4, R bar 3cNa2.5Zr1.8Sc0.2Si1.3P1.7O12, R bar 3c and Na2.7Zr1.8Sc0.2Si1.5P1.5O12, C 2/c. The phosphate (compound 1) exhibit oxygen disorder. The second compound exhibited a similar type of oxygen disorder but also an interstitial Na+ position. The oxygen disorder in compound 2 apparently results from the position of the interstitial Na+ whereas it is suggested that the Sc site in Na2ZrSc(PO4)3 is slightly removed from that of the Zr position, requiring a shift of phosphate groups. In contrast the monoclinic phase does not exhibit oxygen disorder and all the sodium ions reside within the cavities

  2. Hybrid functional study of the NASICON-type Na3V2(PO4)3: crystal and electronic structures, and polaron-Na vacancy complex diffusion.

    Science.gov (United States)

    Bui, Kieu My; Dinh, Van An; Okada, Susumu; Ohno, Takahisa

    2015-11-11

    The crystal and electronic structures, electrochemical properties and diffusion mechanism of NASICON-type Na3V2(PO4)3 have been investigated based on the hybrid density functional Heyd-Scuseria-Ernzerhof (HSE06). A polaron-Na vacancy complex model for revealing the diffusion mechanism is proposed for the first time in the field of Na-ion batteries. The bound polaron is found to favorably form at the first nearest V site to the Na vacancy. Consequently, the movement of the Na vacancy will be accompanied by the polaron. Three preferable diffusion pathways are revealed; these are two intra-layer diffusion pathways and one inter-layer pathway. The activation barriers for the intra-layer and inter-layer pathways are 353 meV and 513 meV, respectively. For further comparison, the generalized gradient approximation with an onsite Coulomb Hubbard U (GGA+U) is also employed. PMID:26509737

  3. Caustic Recycle from Hanford Tank Waste Using Large Area NaSICON Structures (LANS)

    Energy Technology Data Exchange (ETDEWEB)

    Fountain, Matthew S.; Sevigny, Gary J.; Balagopal, S.; Bhavaraju, S.

    2009-03-31

    This report presents the results of a 5-day test of an electrochemical bench-scale apparatus using a proprietary (NAS-GY) material formulation of a (Na) Super Ion Conductor (NaSICON) membrane in a Large Area NaSICON Structures (LANS) configuration. The primary objectives of this work were to assess system performance, membrane seal integrity, and material degradation while removing Na from Group 5 and 6 tank waste from the Hanford Site.

  4. A systematic study of Nasicon-type Li-i + XMXTi2 _ x(PO4)(3) (M: Cr, Al, Fe) by neutron diffraction and impedance spectroscopy.

    Czech Academy of Sciences Publication Activity Database

    Pérez-Estébanez, Marta; Isasi-Marín, J.; Többens, D. M.; Rivera-Calzada, A.; León, C.

    2014-01-01

    Ro?. 266, 15 November (2014), s. 1-8. ISSN 0167-2738 R&D Projects: GA MŠk(CZ) LO1219 Keywords : nasicon-type structure * neutron diffraction * ionic conductivity * occupation factor Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 2.561, year: 2014 http://www.sciencedirect.com/science/journal/01672738/266

  5. Infrared and Raman spectroscopic studies of glasses with NASICON-type chemistry

    Indian Academy of Sciences (India)

    K J Rao; K C Sobha; Sundeep Kumar

    2001-10-01

    Structures of NASICON glasses of the general formula AB2(PO4)3, where A = Li, Na or K and B = Fe, Ga, Ti, V or Nb, have been investigated using vibrational (IR and Raman) spectroscopies. Phosphate species appear to establish an equilibrium via a disproportionation reaction involving a dynamical bond-switching mechanism where both charge and bonds are conserved. B ions in the system acquire different coordinations to oxygens. Alkali ions cause absorptions due to cage vibrations. All the observed spectroscopic features are consistent with speciation involving disproportionation reactions.

  6. A carbon coated NASICON structure material embedded in porous carbon enabling superior sodium storage performance: NaTi2(PO4)3 as an example

    Science.gov (United States)

    Jiang, Yu; Zeng, Linchao; Wang, Jiaqing; Li, Weihan; Pan, Fusen; Yu, Yan

    2015-08-01

    Sodium super ion conductor (NASICON) type structure materials (e.g. Na3V2(PO4)3, NaTi2(PO4)3) have been considered as promising electrode materials for sodium-ion batteries (NIBs). However, the inherent poor electronic conductivity of the NASICON type structure materials owing to their poor electronic conductivity of phosphates leads to poor cyclability and rate capability. Here, we develop a general strategy to achieve high rate capability and long cycle life by preparing ``double carbon coating'' NASICON NaTi2(PO4)3 using a soft-chemical method. The obtained carbon-coated NaTi2(PO4)3 within the porous carbon matrix (denoted as NTP@C@PC) imparts a reversible capability of 103 mA h g-1 at 5 C after 5000 cycles and a rate capability of 64 mA h g-1 at 50 C for sodium storage. The high capacity, stable cyclability and excellent rate capability of the NTP@C@PC are attributed to the advantages of the special structure: the fast Na+/e- transfer in the nanocomposites, large surface area and mesoporous nature of the 3D porous carbon matrix that facilitate the electrolyte to soak in, an intimate interaction between the particles and the carbon matrix. In addition, the 3D porous carbon matrix could effectively accommodate the volume variation during a repeated sodiation/desodiation process.Sodium super ion conductor (NASICON) type structure materials (e.g. Na3V2(PO4)3, NaTi2(PO4)3) have been considered as promising electrode materials for sodium-ion batteries (NIBs). However, the inherent poor electronic conductivity of the NASICON type structure materials owing to their poor electronic conductivity of phosphates leads to poor cyclability and rate capability. Here, we develop a general strategy to achieve high rate capability and long cycle life by preparing ``double carbon coating'' NASICON NaTi2(PO4)3 using a soft-chemical method. The obtained carbon-coated NaTi2(PO4)3 within the porous carbon matrix (denoted as NTP@C@PC) imparts a reversible capability of 103 mA h g-1 at 5 C after 5000 cycles and a rate capability of 64 mA h g-1 at 50 C for sodium storage. The high capacity, stable cyclability and excellent rate capability of the NTP@C@PC are attributed to the advantages of the special structure: the fast Na+/e- transfer in the nanocomposites, large surface area and mesoporous nature of the 3D porous carbon matrix that facilitate the electrolyte to soak in, an intimate interaction between the particles and the carbon matrix. In addition, the 3D porous carbon matrix could effectively accommodate the volume variation during a repeated sodiation/desodiation process. Electronic supplementary information (ESI) available. See DOI: 10.1039/C5NR03978A

  7. Hydrothermal synthesis, structural and physico-chemical characterizations of two Nasicon phosphates: M0.50IITi2(PO4)3 (M = Mn, Co)

    International Nuclear Information System (INIS)

    The family of titanium Nasicon-phosphates of generic formula M0.5IITi2(PO4)3 has been revisited using hydrothermal techniques. Two phases have been synthesized: Mn0.5IITi2(PO4)3 (MnTiP) and Co0.5IITi2(PO4)3 (CoTiP). Single crystal diffraction studies show that they exhibit two different structural types. Mn0.5IITi2(PO4)3 phosphate crystallizes in the R-3 space group, with the cell parameters a = 8.51300(10) A and c = 21.0083(3) A (V = 1318.52(3) A3 and Z = 6). The Co0.5IITi2(PO4)3 phosphate crystallizes in the R-3c space group, with a = 8.4608(9) A and c = 21.174(2) A (V = 1312.7(2) A3 and Z = 6). These two compounds are clearly related to the parent Nasicon-type rhombohedral structure, which can be described using [Ti2(PO4)3] framework composed of two [TiO6] octahedral interlinked via three [PO4] tetrahedra. 31P magic-angle spinning nuclear magnetic resonance (MAS-NMR) data are presented as supporting data. Curie-Weiss-type behavior is observed in the magnetic susceptibility. The phases are also characterized by IR spectroscopy and UV-visible.

  8. Vitrification of K3M2P3O12 (M = B, Al, Bi) NASICON-type materials and electrical relaxation studies

    International Nuclear Information System (INIS)

    Vitreous phases of K3M2P3O12 (M = B, Al, Bi) NASICON-type materials are prepared and their electrical properties are investigated over a frequency range from 42 Hz to 1 MHz and at different temperatures. An anomalous diffusion model (ADM) is applied to discuss the ac conductivity, permittivity and electric modulus of the NASICON-type glasses. The ADM is used to extract the dc conductivity and relevant physical parameters, namely, crossover length and relaxation frequency in the ion diffusion process. The dc conductivities and relaxation frequencies are thermally activated, with activation energies found to be in the range 0.70-0.82 eV. The frequency- and temperature-dependent conductivity spectra of individual glasses can be superimposed by means of the Summerfield scaling

  9. Rare earth fluorescence in NASICON type phosphate glass, Na3TiZnP3O12

    International Nuclear Information System (INIS)

    The emission spectra of Pr3+, Eu3+ and Dy3+ doped in NASICON type phosphate glass, Na3TiZnP3O12 (NTZP) are studied. The dopant rare earth ions occupy sites with 8-9 coordination in a highly covalent environment. For Pr3+ ion, calculated and observed branching ratios for lasing transitions 3P0 ? 3H4.6 agree well and found to be 0.64 and 0.24, respectively. The emissions of Pr3+ show strong temperature dependence on account of Boltzmann population of the higher excited states at room temperature. The excitation spectrum of Eu3+ gives rise to phonon assisted side band for 5D2 7F0 transition at higher energy side with a phonon energy maximum of 1022 cm-1 and an electron phonon coupling strength (g) of 0.018. The value of phonon energy maximum agrees with infrared spectral data. The results show that observation of high energy emissions in phosphate glasses require much higher g values. The red/orange and yellow/blue transitions of Eu3+ and Dy3+, respectively show that the Eu3+ occupy more distorted site than Dy3+. (author)

  10. Hydrothermal synthesis, structure and characterization of new NASICON related potassium iron (III) pyrophosphate

    Indian Academy of Sciences (India)

    G S Gopalakrishna; B H Doreswamy; M J Mahesh; M Mahendra; M A Sridhar; J Shashidhara Prasad; K G Ashamanjari

    2005-02-01

    A new potassium iron (III) pyrophosphate was synthesized by hydrothermal technique and characterized by X-ray studies. The compound crystallizes in a monoclinic space group, 21/, with cell parameters, = 7.365(2) Å, = 10.017(2) Å, = 8.214(1) Å, = 106.50(1)° and = 4. The structure has tunnel-type cavities and are congenial for ion transportation through them. The compound exhibits moderate thermal stability.

  11. Vitrification of K{sub 3}M{sub 2}P{sub 3}O{sub 12} (M = B, Al, Bi) NASICON-type materials and electrical relaxation studies

    Energy Technology Data Exchange (ETDEWEB)

    Mariappan, C.R. [Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, R.V. Nagar, Kalapet, Pondicherry 605014 (India); Govindaraj, G. [Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, R.V. Nagar, Kalapet, Pondicherry 605014 (India)]. E-mail: ggraj_7@yahoo.com; Rathan, S. Vinoth [Department of Physics, School of Physical, Chemical and Applied Sciences, Pondicherry University, R.V. Nagar, Kalapet, Pondicherry 605014 (India); Prakash, G. Vijaya [School of Physics and Astronomy, University of Southampton Highfield, Southampton S017 1BJ (United Kingdom)

    2005-11-15

    Vitreous phases of K{sub 3}M{sub 2}P{sub 3}O{sub 12} (M = B, Al, Bi) NASICON-type materials are prepared and their electrical properties are investigated over a frequency range from 42 Hz to 1 MHz and at different temperatures. An anomalous diffusion model (ADM) is applied to discuss the ac conductivity, permittivity and electric modulus of the NASICON-type glasses. The ADM is used to extract the dc conductivity and relevant physical parameters, namely, crossover length and relaxation frequency in the ion diffusion process. The dc conductivities and relaxation frequencies are thermally activated, with activation energies found to be in the range 0.70-0.82 eV. The frequency- and temperature-dependent conductivity spectra of individual glasses can be superimposed by means of the Summerfield scaling.

  12. Characterization of soft-combustion-derived NASICON-type Li2Co2(MoO4)3 for lithium batteries

    International Nuclear Information System (INIS)

    This work describes the synthesis of a new polyanion material, Li2Co2(MoO4)3, belonging to the NASICON family. A low-temperature soft-combustion method using glycine as a soft-combustion fuel was adopted to obtain single-phase powders of the new material at a temperature as low as 300 deg. C. Li2Co2(MoO4)3 was found to crystallize in an orthorhombic structure (space group Pmmm) with lattice parameters a = 17.584(7) A, b 10.464(4) A and c = 5.102(9) A. The electronic state of each element present in the new material was confirmed by X-ray photoelectron spectroscopic analysis. The powders were analyzed using inductively coupled plasma emission spectroscopy. The microstructural analysis revealed that the particles (5-10 ?m) have a rather columnar shape. The electrochemistry redox behavior of the new material was studied, for the first time, and the material as positive electrode was found to exhibit topotactic Li+ extraction/insertion in lithium-containing test cells

  13. Ion conductivity of nasicon ceramics

    International Nuclear Information System (INIS)

    The Nasiconss,Na1+XZr2SiXP3-XO12 o , X , 3, includes some of the best solid state sodium conductors known today. Compositions in the interval 1.6 , X , 2.6 show conductivities comparable to the best ? double-prime-alumina ceramics. It is well known that the ion conductivity of ?-alumina is strongly dependent on the texture of the ceramic. Here a similar behavior is reported for Nasicon ceramics. Ceramics of the bulk composition Na2.94Zr1.49Si2.20P0.80O10.85 were prepared by a gel method. The final ceramics consist of Nasicon crystals with x = 2.14 and a glass phase. The grain size and texture of the ceramics were controlled by varying the thermal history of the gel based raw materials and the sintering conditions. The room temperature resistivity of the resulting ceramics varies from 3.65*103 ohm cm to 1.23*103 ohm cm. Using the temperature comparison method and estimates of the area of grain boundaries in the ceramics, the resistivity of the Nasicon phase is estimated to be 225 ohm cm at 25 degrees C. B2O3- or Al2O3-doping of the glass bearing Nasicon ceramic lower the room temperature resistivity by a factor 2 to 5. The dopants do not substitute into the Nasicon phase in substantial amounts

  14. Hydrothermal synthesis, structural and physico-chemical characterizations of two Nasicon phosphates: M0,50IITi2(PO4)3 (M = Mn, Co).

    Czech Academy of Sciences Publication Activity Database

    Essehli, R.; El Bali, B.; Benmokhtar, S.; Fejfarová, Karla; Dušek, Michal

    2009-01-01

    Ro?. 44, ?. 7 (2009), s. 1502-15010. ISSN 0025-5408 R&D Projects: GA ?R GA202/06/0757 Institutional research plan: CEZ:AV0Z10100521 Keywords : X-ray diffraction * Jana 2006 * Nasicon-phosphates Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.879, year: 2009

  15. Synthesis of Li{sub 1}+xM{sup I}II{sub x}Ti{sub 2}-x(PO{sub 4}){sub 3} with nasicon structure, using sol-gel methods. Study of the relationship microstructure electrical properties; Sintesis mediante quimica sol gel de compuestos Li{sub 1}+xM{sup I}II{sub x}Ti{sub 2}-x(PO{sub 4}){sub 3} con estructura tipo Nasicon. Estudio de la relacion microestructura-propiedades electricas

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Estebanez, M.; Rivera-Calzada, A.; Leon, C.; Santamaria, J.; Isasi-Marin, J.

    2010-07-01

    Compounds of formula Li{sub 1}+xM{sup I}II{sub x}Ti{sub 2}-x(PO{sub 4}){sub 3} with M{sup I}II = Cr, Fe and x = 0 and 0.05 have been prepared at soft temperatures using the Pechini synthesis method, based on sol-gel chemistry. The structural and microstructural characterization by X-ray diffraction and Scanning Electron Microscopy (SEM), shows that all of them crystallize in a NASICON-type structure with similar lattice parameters. Doping with Fe and Cr, causes an increase of the density of the samples after sinterization what clearly improves the ionic conductivity of the original material, LiTi{sub 2}(PO{sub 4}){sub 3} until values of 9x10{sup -}4 S cm{sup -}1 at room temperature in the chromium-doped material. (Author)

  16. Synthesis, structure and characterisation of Fe0.50Ti2(PO4)3: A new material with Nasicon-like structure

    International Nuclear Information System (INIS)

    A new iron titanyl phosphate Fe0.50Ti2(PO4)3 was synthesized by both solid-state reaction and Cu2+-Fe2+ ion exchange method. The material was then characterized by X-ray diffraction, Mossbauer, magnetic susceptibility measurements and optical absorption. The crystal structure of the compound was refined, using X-ray powder diffraction data, by the Rietveld profile method; it crystallizes in the rhombohedral system, space group R3-bar, with a=8.511(1)A and c=20.985(3)A, V=1316.45(3)A3 and Z=6. The structure, which is compared to that of Mn0.50Ti2(PO4)3 is built up from [TiO6] octahedra and [PO4] tetrahedra which are linked by corner sharing along the c-axis. Fe2+ cations are located in half of the antiprism MI sites and are orderly distributed with vacancies within the two possible positions of the MI sites of R3-bar. These results were supported by the Mossbauer studies that showed the presence of one Fe2+ site in the high spin state (t2g4eg2). The Curie-Weiss-type behavior is observed in the magnetic susceptibility. Diffuse reflectance spectrum indicates the presence of octahedrally coordinated Fe2+ ions

  17. Li mobility in Nasicon-type materials LiM2(PO4)3, M = Ge, Ti, Sn, Zr and Hf, followed by 7Li NMR spectroscopy.

    Science.gov (United States)

    Arbi, K; París, M A; Sanz, J

    2011-10-21

    Lithium mobility in LiM(2)(PO(4))(3) compounds, M = Ge and Sn, has been investigated by (7)Li Nuclear Magnetic Resonance (NMR) spectroscopy, and deduced information compared with that reported previously in Ti, Zr and Hf members of the series in the temperature range 100-500 K. From the analysis of (7)Li NMR quadrupole interactions (C(Q) and ? parameters), spin-spin T(2)(-1) and spin-lattice T(1)(-1) relaxation rates, structural sites occupancy and mobility of lithium have been deduced. Below 250 K, Li ions are preferentially located at M(1) sites in rhombohedral phases, but occupy intermediate M(12) sites between M(1) and M(2) sites in triclinic ones. In high-temperature rhombohedral phases, a superionic state is achieved when residence times at M(1) and M(12) sites become similar and correlation effects on Li motion decrease. This state can be obtained by large order-disorder transformations in rhombohedral phases or by sharp first order transitions in triclinic ones. The presence of two relaxation mechanisms in T(1)(-1) plots of rhombohedral phases has been associated with departures of conductivity from the Arrhenius behavior. Long term mobility of lithium is discussed in terms of the cation vacancy distribution along conduction paths. PMID:21897945

  18. Synthesis and properties of nasicon prepared from different zirconia-based precursors

    Directory of Open Access Journals (Sweden)

    Fuentes, R. O.

    1999-12-01

    Full Text Available This work reports on the synthesis and characterization of NASICON prepared from SiO2, Na3PO4.12H2O and two types of zirconia: pure monoclinic ZrO2 and TZP (Tetragonal Polycrystalline Zirconia, with 3 mol% Y2O3 as raw materials. The classical ceramic method was used in all cases. SEM, XRD and DTA were used to follow the synthesis and sintering process, and impedance spectroscopy (IS was used to study the electrical properties of sintered pellets. Results obtained with different NASICON samples showed a significant role of composition and processing conditions on the electrical properties. Samples based on TZP, sintered at 1210ºC, exhibited densities of about 3.20 g/cm3 (98% of theoretical density of NASICON and ionic conductivities of about 2x10-3 S.cm-1 at room temperature a rather interesting result when compared with data obtained with the material prepared from pure ZrO2.

    Este trabajo trata de la síntesis y caracterización de NASICON preparado a partir de SiO2 , Na3PO4.12H2O y dos tipos de circonia, ZrO2 monoclínica pura y TZP (circonia policristalina tetragonal, con 3 moles% Y2O3 como materia prima. Se emplea el método cerámico clásico en todos los casos. Las técnicas de MEB, DRX y ATD se emplean para seguir la síntesis y el proceso de sinterización. La espectroscopia de impedancia compleja se emplea para estudiar las propiedades eléctricas de las muestras sinterizadas. Los resultados obtenidos con diferentes muestras de NASICON mostraron un papel significativo de la composición y condiciones de procesamiento sobre las propiedades eléctricas. Las muestras basadas en TZP, sinterizadas a 1210ºC, presentan densidades alrededor de 3.20 g/cm3 (98% de la densidad teórica del NASICON y conductividad iónica de 2x 10-3 5.cm-1 a temperatura ambiente, un resultado bastante interesante cuando se compara con datos obtenidos con material preparado de ZrO2 pura.

  19. Restrictions to obtain NASICON by a ceramic route

    Directory of Open Access Journals (Sweden)

    Fuentes, R. O.

    2004-08-01

    Full Text Available Highly reactive monoclinic ZrO2 powders were mixed with Na3PO4•12H2O and amorphous SiO2 in the stoichiometric quantities to obtain Na3Zr2Si2PO12. The mixtures were calcined at different temperatures (Tcalc and for variable periods of time (tcalc. Their morphology was analysed by SEM and the composition by powder XRD. NASICON reflections are not detected for Tcalc=900°C and for relatively short tcalc values of 2 h. At 1100°C, the onset of low intensity NASICON peaks indicate the early stages of the formation reaction which is significantly enhanced when Tcalc increases up to 1200 and 1300°C. For higher temperatures, an apparent decrease of the reaction rate is suggested. On the other hand, the intensities of the ZrO2 peaks suffer a drastic decrease when Tcalc varies from 900 to 1300°C, followed by a slight increase for Tcalc=1400°C. The studies were extended for mixtures kept in isothermal conditions at 1100, 1200 and 1300°C during 0.5, 1, 2, 4, 8 and 16 h. In the three temperatures, the increase of the tcalc up to ca. 4 h leads to a significant increase in the intensity of the NASICON reflections while that of mZrO2 decreases. A plateau is apparent for higher tcalc values suggesting that equilibrium may be attained. The use of a highly reactive tetragonal zirconia powder (also thermodynamically unstable at low temperature clearly improved the overall reaction extension and kinetics at moderate temperatures, yielding a single phase product.

    Polvos de ZrO2 monoclínica altamente reactivos fueron mezclados con Na3PO4•12H2O y SiO2 amorfo en cantidades apropiadas para obtener Na3Zr2Si2PO12. Las mezclas fueron calcinadas a diferentes temperaturas (Tcalc y diferentes tiempos (tcalc y caracterizadas por SEM y DRX. Líneas características del NASICON no son detectadas a Tcalc=900°C y a tiempos de calcinado relativamente cortos (< 2h. A 1100°C, la presencia de picos de NASICON de baja intensidad indica los primeros momentos de la reacción de formación, la cual es significativamente mejorada cuando Tcalc es aumentada a 1200 y 1300°C. Para altas temperaturas (< 1300ºC, se sugiere una aparente disminución de la velocidad de reacción. Por otra parte, la intensidad de los picos de ZrO2 sufren una drástica disminución cuando Tcalc varía desde 900 a 1300°C, seguido de un leve incremento a Tcalc=1400°C. Los estudios fueron realizados manteniendo condiciones isotérmicas a 1100, 1200 y 1300°C durante 0,5, 1, 2, 4, 8 y 16 h. En las tres temperaturas, el aumento de tcalc hasta 4 h conduce a un marcado aumento de la intensidad de las líneas características del NASICON, mientras que las correspondientes a mZrO2 disminuyen. Un “plateau” es observado a valores altos de tcalc, lo que sugiere que un equilibrio está siendo alcanzado. La utilización de polvos altamente reactivos de ZrO2 tetragonal (termodinámicamente inestable a baja temperatura mejoró claramente la extensión y la cinética de reacción a temperaturas moderadas, conduciendo a la formación de un producto monofásico.

  20. Time of flight neutron Rietveld refinement study at elevated temperature on a monoclinic near-stoichiometric NASICON

    International Nuclear Information System (INIS)

    Time of flight neutron powder data were collected at elevated temperatures on a sample of NASICON of composition Na/sub 3.17/Zr/sub 1.93/Si/sub 1.9/O12. This sample, prepared by reheating a commercially available NASICON to minimize the ZrO2 impurity, has been previously structurally refined from room temperature neutron diffraction data collected at Argonne National Laboratory. Conductivity measurements show a cusp at ca. 1700C attributed to the monoclinic-rhombohedral transition and the purpose of this work was to explore the nature of the transition. Data runs were made at 143, 173, 202, 300, and 3910C. No evidence for a crystal system change was found. The highest temperature data sets could not be refined satisfactorily by the Rietveld method using a rhombohedral model, but rather required a monoclinic cell in space group C2/c to achieve convergence. An explanation for the conductivity cusp is given in terms of disordering of the sodium ions and a change in conduction pathways which lowers the barriers to ion movement

  1. High-voltage NASICON Sodium Ion Batteries: Merits of Fluorine Insertion

    International Nuclear Information System (INIS)

    Graphical abstract: Fluorine participation in crystal structure construction in Na3V2(PO4)3 to form Na3V2(PO4)2F3, displays several effects on the ions configuration involving ions occupation, species and amount of diverse Na sites, and the electronic cloud density upon compositional atoms leading to distinct modalities for ions extraction as well as the operating voltages. - Abstract: NASICON Na3V2(PO4)3 and Na3V2(PO4)2F3 have restarted to be investigated electrochemically as promising cathode materials for sodium-ion batteries. Fluorine insertion by replacing partial phosphate groups in Na3V2(PO4)3 allows for new family of host lattice structure, Na3V2(PO4)2F3. Greatly, fluorine is capable to participate in structural construction to change the ions configuration which involves ions occupation, the species and amount of diverse Na sites, leading to distinct modalities for ions extraction. The inductive effects of (PO4)3? polyanion by changing electronic cloud density upon compositional atoms could be enhanced under the effects of the formed F-V bond due to its strong ionicity, which can moderate the energetics of the transition metal redox couple to generate relatively high operating potentials. The substitution of fluorine for negative-charge polyanion or anion could be effective to improve the electrochemical properties, particularly for the purpose to increase performed voltages by changing atomic environments

  2. An all-solid state NASICON sodium battery operating at 200 °C

    Science.gov (United States)

    Lalère, F.; Leriche, J. B.; Courty, M.; Boulineau, S.; Viallet, V.; Masquelier, C.; Seznec, V.

    2014-02-01

    An all-solid state symmetric monolithic sodium ion battery operating at 200 °C is described, using NASICON-type electrodes and electrolyte. Na3V2(PO4)3 is used at both electrodes as the active material while Na3Zr2Si2PO12 stands the role of the Na+ solid electrolyte. Both compositions present order-disorder phase transitions and present decent ionic conductivity properties, 1.5 × 10-3 S cm-1 and 1.9 × 10-4 S cm-1 at 200 °C for Na3Zr2Si2PO12 and Na3V2(PO4)3, respectively. The full battery (560 ?m in thickness) was assembled in a 10? single step by spark plasma sintering at 900 °C. The electrochemical characteristics at high temperature (200 °C) were evaluated thanks to a new experimental set-up. The battery operates at 1.8 V with 85% of the theoretical capacity attained at C/10 with satisfactory capacity retention, for an overall energy density of 1.87 × 10-3 W h cm-2 and a capacity of 1.04 mA h cm-2.

  3. Structural and electrochromic properties of Fe2(SO4)3 nanostructures prepared by template assisted method

    Science.gov (United States)

    Sahana M., B.; Chandran, Sudakar; Naik, Ratna; Naik, Vaman

    2010-04-01

    Oxides containing polyanions such as XO4^2- (X = S, Mo, P and W) as lithium insertion hosts are promising cathode materials due to their high thermal stability. However, the larger separation of the transition metal ions can be expected to reduce the electron mobility. As observed in LiFePO4, this can be overcome either by coating the cathode materials with carbon or by decreasing the particle size. We have prepared nanowires of NASICON type structure and platelets of monoclinic Fe2(SO4)3 by template assisted electro deposition. These structures were grown on stainless steel substrates and are characterized by XPS, HRTEM, and XRD analysis. Both NASICON and monoclinic Fe2(SO4)3 structures are very porous and are comprised of nanoparticles leading to a high lithium insertion capacity.

  4. Effect of substituting Ce for Zr on the electrical properties of NASICON materials

    Science.gov (United States)

    Xie, Bingxing; Jiang, Danyu; Wu, Jian; Feng, Tao; Xia, Jinfeng; Nian, Hongqiang

    2016-01-01

    By investigation of the microstructure of cerium-doped NASICON materials prepared by solid state reaction, we find that variation in the cell parameters a, b and c can affect their activation energy (Ea) of ionic conductance. Furthermore, changes in the grain size and morphology can influence the pre-exponential factor ?0. Analysis of the electrical conductivity of cerium-doped NASICON grains reveals a decrease from that for the undoped grains. These results suggest that when dealing with Ce-doped NASICON system, the grain size and morphology play a more important role in determining the bulk conductivity than the lattice parameters, at least within a temperature range of 225-350 °C.

  5. Nomenclature of inorganic structure types

    International Nuclear Information System (INIS)

    Different degrees of similarity between inorganic crystal structures are defined concisely and examples are presented that illustrate their practical application. A notation giving the coordination of atoms is presented together with some basic rules for developing crystal-chemical formulae and the Bauverband description of inorganic structure types. Typical examples of the nomenclature are: pyrite Fe[6o]{g}[S2[3;1)t

  6. Parsing with Typed Feature Structures

    CERN Document Server

    Wintner, S; Wintner, Shuly; Francez, Nissim

    1996-01-01

    In this paper we provide for parsing with respect to grammars expressed in a general TFS-based formalism, a restriction of ALE. Our motivation being the design of an abstract (WAM-like) machine for the formalism, we consider parsing as a computational process and use it as an operational semantics to guide the design of the control structures for the abstract machine. We emphasize the notion of abstract typed feature structures (AFSs) that encode the essential information of TFSs and define unification over AFSs rather than over TFSs. We then introduce an explicit construct of multi-rooted feature structures (MRSs) that naturally extend TFSs and use them to represent phrasal signs as well as grammar rules. We also employ abstractions of MRSs and give the mathematical foundations needed for manipulating them. We then present a simple bottom-up chart parser as a model for computation: grammars written in the TFS-based formalism are executed by the parser. Finally, we show that the parser is correct.

  7. Parsing with Typed Feature Structures

    CERN Document Server

    Wintner, S; Wintner, Shuly; Francez, Nissim

    1996-01-01

    In this paper we provide for parsing with respect to grammars expressed in a general TFS-based formalism, a restriction of ALE. Our motivation being the design of an abstract (WAM-like) machine for the formalism, we consider parsing as a computational process and use it as an operational semantics to guide the design of the control structures for the abstract machine. We emphasize the notion of abstract typed feature structures (AFSs) that encode the essential information of TFSs and define unification over AFSs rather than over TFSs. We then introduce an explicit construct of multi-rooted feature structures (MRSs) that naturally extend TFSs and use them to represent phrasal signs as well as grammar rules. We also employ abstractions of MRSs and give the mathematical foundations needed for manipulating them. We formally define grammars and the languages they generate, and then describe a model for computation that corresponds to bottom-up chart parsing: grammars written in the TFS-based formalism are executed...

  8. Type-II Matrices and Combinatorial Structures

    OpenAIRE

    Chan, Ada; Godsil, Chris

    2007-01-01

    Type-II matrices are a class of matrices used by Jones in his work on spin models. In this paper we show that type-II matrices arise naturally in connection with some interesting combinatorial and geometric structures.

  9. Structural trends in pyrochlore-type oxides

    Science.gov (United States)

    Kennedy, Brendan J.

    1998-04-01

    Structural trends in some pyrochlore-type A2B2O7 oxides are reviewed and some new structural data is presented. Powder neutron diffraction data have shown that, for B=Ru or Ir, the presence of an easily polarisable cation on the pyrochlore A site and anion vacancies results in structural changes consistent with the oxidation of the B-type cation. An explanation for this observation is presented.

  10. SO2-sensing characteristics of NASICON sensors with ZnSnO3 sensing electrode

    International Nuclear Information System (INIS)

    A compact tubular sensor based on sodium super ionic conductor (NASICON) and ZnSnO3 sensing electrode was designed for the detection of sulfur dioxide. The NASICON and ZnSnO3 material were prepared by sol-gel method and were analyzed by the X-ray diffraction (XRD) analysis, respectively. And ZnSnO3 materials were analyzed by SEM. ZnSnO3 thick film was prepared to investigate characteristics of sulfur dioxide (SO2) at various operating temperatures. The sensor using ZnSnO3 gave excellent sensing properties to 5-50 ppm SO2 in air at 360-390 deg. C. The EMF value of the sensor was almost proportional to the logarithm of SO2 concentration, the sensitivity (slope) was 255 mV/decade at 375 deg. C. It was also seen that the sensor showed a good selectivity to SO2 against H2S, NO2, Cl2, NO and C7H8. The sensor had speedy response kinetics to SO2 too, the 90% response time to 5, 10, 20 and 50 ppm SO2 was 18, 10, 8 and 5 s, respectively, and the recovery time was 27, 99, 184 and 243 s, respectively. Finally, a sensing mechanism involved the mixed potential was proposed

  11. Structure of a Type IV Secretion System

    OpenAIRE

    Low, Harry H.; Gubellini, Francesca; Rivera-Calzada, Angel; Braun, Nathalie; Connery, Sarah; Dujeancourt, Annick; Lu, Fang; Redzej, Adam; Fronzes, Rémi; Orlova, Elena V.; Waksman, Gabriel

    2014-01-01

    Bacterial type IV secretion (T4S) systems translocate virulence factors into eukaryotic cells1,2, distribute genetic material between bacteria, and have shown potential as a tool for the genetic modification of human cells3. Given the complex choreography of the substrate through the secretion apparatus4, the molecular mechanism of the T4S system has proven difficult to dissect in the absence of structural data for the entire machinery. Here we use electron microscopy (EM) to reconstruct the ...

  12. Investigating The Algebraic Structure of Dihomotopy Types

    CERN Document Server

    Gaucher, P

    2001-01-01

    This presentation is the sequel of a paper published in GETCO'00 proceedings where a research program to construct an appropriate algebraic setting for the study of deformations of higher dimensional automata was sketched. This paper will be focused precisely on detailing some of its aspects. The main idea is that the category of homotopy types can be embedded in a new category of dihomotopy types, the embedding being realized by the Globe functor. In this latter category, isomorphism classes of objects are exactly higher dimensional automata up to deformations leaving invariant their computer scientific properties as presence or not of deadlocks (or everything similar or related). Some hints to study the algebraic structure of dihomotopy types are given, in particular a rule to decide whether a statement/notion concerning dihomotopy types is or not the lifting of another statement/notion concerning homotopy types. This rule does not enable to guess what is the lifting of a given notion/statement, it only ena...

  13. Extraordinary electronic properties in uncommon structure types

    Science.gov (United States)

    Ali, Mazhar Nawaz

    In this thesis I present the results of explorations into several uncommon structure types. In Chapter 1 I go through the underlying idea of how we search for new compounds with exotic properties in solid state chemistry. The ideas of exploring uncommon structure types, building up from the simple to the complex, using chemical intuition and thinking by analogy are discussed. Also, the history and basic concepts of superconductivity, Dirac semimetals, and magnetoresistance are briefly reviewed. In chapter 2, the 1s-InTaS2 structural family is introduced along with the discovery of a new member of the family, Ag0:79VS2; the synthesis, structure, and physical properties of two different polymorphs of the material are detailed. Also in this chapter, we report the observation of superconductivity in another 1s structure, PbTaSe2. This material is especially interesting due to it being very heavy (resulting in very strong spin orbit coulping (SOC)), layered, and noncentrosymmetric. Electronic structure calculations reveal the presence of a bulk 3D Dirac cone (very similar to graphene) that is gapped by SOC originating from the hexagonal Pb layer. In Chapter 3 we show the re-investigation of the crystal structure of the 3D Dirac semimetal, Cd3As2. It is found to be centrosymmetric, rather than noncentrosymmetric, and as such all bands are spin degenerate and there is a 4-fold degenerate bulk Dirac point at the Fermi level, making Cd3As2 a 3D electronic analog to graphene. Also, for the first time, scanning tunneling microscopy experiments identify a 2x2 surface reconstruction in what we identify as the (112) cleavage plane of single crystals; needle crystals grow with a [110] long axis direction. Lastly, in chapter 4 we report the discovery of "titanic" (sadly dubbed ?rge, nonsaturating" by Nature editors and given the acronym XMR) magnetoresistance (MR) in the non-magnetic, noncentrosymmetric, layered transition metal dichalcogenide WTe2; over 13 million% at 0.53 K in a magnetic field of 60 Tesla (the largest positive magnetoresistance ever reported). Unlike what is seen in other known materials, there is no saturation of the magnetoresistance value even at very high applied fields. In semimetals, very high MR may attributed to a balanced hole-electron "resonance" condition; as described here, WTe2 appears to be the first known material where this resonance is nearly perfect.

  14. Interference enhanced thermoelectricity in quinoid type structures.

    Science.gov (United States)

    Strange, M; Seldenthuis, J S; Verzijl, C J O; Thijssen, J M; Solomon, G C

    2015-02-28

    Quantum interference (QI) effects in molecular junctions may be used to obtain large thermoelectric responses. We study the electrical conductance G and the thermoelectric response of a series of molecules featuring a quinoid core using density functional theory, as well as a semi-empirical interacting model Hamiltonian describing the ?-system of the molecule which we treat in the GW approximation. Molecules with a quinoid type structure are shown to have two distinct destructive QI features close to the frontier orbital energies. These manifest themselves as two dips in the transmission, that remain separated, even when either electron donating or withdrawing side groups are added. We find that the position of the dips in the transmission and the frontier molecular levels can be chemically controlled by varying the electron donating or withdrawing character of the side groups as well as the conjugation length inside the molecule. This feature results in a very high thermoelectric power factor S(2)G and figure of merit ZT, where S is the Seebeck coefficient, making quinoid type molecules potential candidates for efficient thermoelectric devices. PMID:25725747

  15. Mullite and mullite-type crystal structures

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, Reinhard X.; Gaede-Koehler, Andrea; Birkenstock, Johannes [Bremen Univ. (Germany). Fachbereich Geowissenschaften; Schneider, Hartmut [Bremen Univ. (Germany). Fachbereich Geowissenschaften; Koeln Univ. (Germany). Inst. fuer Kristallographie

    2012-04-15

    Synthetic mullites (Al{sub 4+2x}Si{sub 2-2x}O{sub 10-x}) belong to one of the most important groups of ceramic materials. Their crystal structure consists of chains of edge-sharing AlO{sub 6} octahedra interconnected by tetrahedral double chains of TO{sub 4} (T = Al, Si) tetrahedra. The occurrence of oxygen vacancies is associated with the formation of triclusters of TO{sub 4} groups. The distribution of oxygen vacancies and the distribution of Al and Si on the tetrahedral sites are partially ordered yielding an incommensurately modulated crystal structure with satellite reflections in diffraction patterns. The number of symmetrically independent distribution patterns of oxygen vacancies is given for a 2 x 2 x 2 and a 3 x 3 x 2 superstructure model. Many other compounds have chain structures similar to mullite. These compounds are assigned to subgroups, all derived from a hypothetical tetragonal aristotype structure. (orig.)

  16. Types and Functions of Coastal Structures

    OpenAIRE

    Burcharth, H. F.; A. Hughes, Steven

    2005-01-01

    Coastal structures are used in coastal defence schemes with the objective of preventing shoreline erosion and flooding of the hinterland. Other objectives include sheltering of harbour basins and harbour entrances against waves, stabilization of navigation channels at inlets, and protection of water intakes and outfalls.

  17. Types and Functions of Coastal Structures

    DEFF Research Database (Denmark)

    Burcharth, H. F.; A. Hughes, Steven

    2003-01-01

    Coastal structures are used in coastal defence schemes with the objective of preventing shoreline erosion and flooding of the hinterland. Other objectives include sheltering of harbour basins and harbour entrances against waves, stabilization of navigation channels at inlets, and protection of water intakes and outfalls.

  18. Hodge-type structures as link invariants

    OpenAIRE

    Borodzik, Maciej; Nemethi, Andras

    2010-01-01

    Based on some analogies with the Hodge theory of isolated hypersurface singularities, we define Hodge-type numerical invariants (called H-numbers) of any, not necessarily algebraic, link in $S^3$. They contain the same information as the (normalized) real Seifert matrix. We study their basic properties, we express the Tristram-Levine signatures and the higher order Alexander polynomial in terms of them. Motivated by singularity theory, we also introduce the spectrum of the link (determined fr...

  19. Vibrational spectra of complex oxides with the perovskite type structure

    International Nuclear Information System (INIS)

    Some aspects of crystal chemistry and vibrational spectroscopy of complex oxides with the perovskite type structure are considered. A review of the investigation results of complex oxides of rhenium, tungsten, niobium, and tantalum with the perovskite type structure obtained by the vibrational spectroscopy methods (IR absorption, Raman spectroscopy) is presented. 34 refs.; 4 tabs

  20. Prediction of Type A behaviour : a structural equation model

    OpenAIRE

    Marius Pretorius; Gideon Nieman; Jurie van Vuuren; André B. Boshoff; René van Wyk

    2009-01-01

    The predictability of Type A behaviour was measured in a sample of 375 professionals with a shortened version of the Jenkins Activity Survey (JAS). Two structural equation models were constructed with the Type A behaviour achievement sub-scale and global (total) Type A as the predictor variables. The indices showed a reasonable-to-promising fit with the data. Type A achievement was reasonably predicted by service-career orientation, internal locus of control, power self-concept and economic i...

  1. Excitonic fine structure splitting in type-II quantum dots

    OpenAIRE

    K?ápek, Vlastimil; Klenovský, Petr; Šikola, Tomáš

    2015-01-01

    Excitonic fine structure splitting in quantum dots is closely related to the lateral shape of the wave functions. We have studied theoretically the fine structure splitting in InAs quantum dots with a type-II confinement imposed by a GaAsSb capping layer. We show that very small values of the fine structure splitting comparable with the natural linewidth of the excitonic transitions are achievable for realistic quantum dot morphologies despite the structural elongation and t...

  2. The market for HTGR type reactors with modular structure

    International Nuclear Information System (INIS)

    After a brief explanation relating to the fields of application of the HTGR type reactors with modular structures, the author refers to the specific costs of the system, its profitability, and the market potential, both domestic and abroad. (UA)

  3. Co-linear spin configurations in corundum-type structures

    International Nuclear Information System (INIS)

    The colinear magnetic configurations possible in corundum-type structures (?-Fe2O3; Cr2O3) are solutions of a matrices problem. Their regions of stability are bounded by inequality relationships between exchange integrals. (author)

  4. Prediction of Type A behaviour: a structural equation model

    Scientific Electronic Library Online (English)

    René, van Wyk; André B., Boshoff; Gideon, Nieman; Jurie, van Vuuren; Marius, Pretorius.

    Full Text Available The predictability of Type A behaviour was measured in a sample of 375 professionals with a shortened version of the Jenkins Activity Survey (JAS). Two structural equation models were constructed with the Type A behaviour achievement sub-scale and global (total) Type A as the predictor variables. Th [...] e indices showed a reasonable-to-promising fit with the data. Type A achievement was reasonably predicted by service-career orientation, internal locus of control, power self-concept and economic innovation. Type A global was also predicted by internal locus of control, power self-concept and the entrepreneurial attitude of achievement and personal control.

  5. Prediction of type A behaviour: A structural equation model

    Directory of Open Access Journals (Sweden)

    René van Wyk

    2009-04-01

    Full Text Available The predictability of Type A behaviour was measured in a sample of 375 professionals with a shortened version of the Jenkins Activity Survey (JAS. Two structural equation models were constructed with the Type A behaviour achievement sub-scale and global (total Type A as the predictor variables. The indices showed a reasonable-to-promising fit with the data. Type A achievement was reasonably predicted by service-career orientation, internal locus of control, power self-concept and economic innovation. Type A global was also predicted by internal locus of control, power self-concept and the entrepreneurial attitude of achievement and personal control.

  6. Sums of correlated exponentials: two types of Gaussian correlation structures

    OpenAIRE

    Klymovskiy, Anton (Klimovsky, Anton)

    2008-01-01

    In this thesis, we study the limiting behaviour of the large sums of strongly correlated exponentials as the number of their summands and the effective dimension of the correlation structure simultaneously tend to infinity. We consider two types of such sums which are generated by two a priori very different Gaussian correlation structures. The first type is a sum of hierarchically correlated random variables which is based on the partition function of Derrida's generalised random energy mode...

  7. Crystallostructural features of ion transport in new OD-structures: catapleite Na2ZrSi3O9·2H2O and ilerite Na2ZrSi3O9·3H2O

    International Nuclear Information System (INIS)

    The formation of new OD-structures in the class of alkali MT-compounds (M=Zr, Sc, rare earths, T=Si, P) with disordered Na sublattice is analized. The experimental proof of ion conductivity presence is obtained and a reversible phase transition is registered for the synthetic catapleite analog crystallizing in the hydrothermal system ZrO2-SiO2-NaOH-H2O. Crystallostructural features of phase transitions in catapleite (of the shift type) and Zr- and Sc-NASICON (transitions of the order-disorder type) are considered. Compounds with two-dimensional Na-sublattices are found for the first time among three-dimensional MT-structures with disordered Na-sublattice which permits to use catapleite and ilerite crystals as the object for detail study of ion-transport characteristics anisotropy

  8. Implementing semantic frames as typed feature structures with XMG

    Directory of Open Access Journals (Sweden)

    Timm Lichte

    2015-07-01

    Full Text Available This work presents results on the integration of frame-based representations into the framework of eXtensible MetaGrammar (XMG. Originally XMG allowed for the description of tree-based syntactic structures and underspecified representations of predicate-logical formulae, but the representation of frames as a sort of typed feature structure, particularly type unification, was not supported. Therefore, we introduce an extension that is capable of handling frame representations directly by means of a novel -dimension. The aim is not only to make possible a straightforward specification of frame descriptions, but also to offer various ways to specify constraints on types, be it as a contiguous type hierarchy or a loose set of feature structure constraints. The presented extensions to XMG are fully operational in a new prototype.

  9. Soil structure interactions of eastern U.S. type earthquakes

    International Nuclear Information System (INIS)

    Two types of earthquakes have occurred in the eastern US in the past. One of them was the infrequent major events such as the 1811-1812 New Madrid Earthquakes, or the 1886 Charleston Earthquake. The other type was the frequent shallow earthquakes with high frequency, short duration and high accelerations. Two eastern US nuclear power plants, V.C Summer and Perry, went through extensive licensing effort to obtain fuel load licenses after this type of earthquake was recorded on sites and exceeded the design bases beyond 10 hertz region. This paper discusses the soil-structure interactions of the latter type of earthquakes

  10. Fe-doped ?-Rhombohedral boron: Structural changes at the p-type/n-type transition

    Science.gov (United States)

    Werheit, H.; Filipov, V.; Kuhlmann, U.; Dose, T.; Lundström, T.

    2015-09-01

    n-type ?-rhombohedral boron is e.g. obtained by interstitial doping with Fe atoms exceeding 2.45 at.%. The spectra of Raman- and IR-active phonons have been measured up to the solubility limit of ?4 at.%. Numerous significant discontinuities in the spectra indicate structural changes at the p/n-transition. These might be restricted to specific elements of the structure, as the lattice parameters vary continuously, thus indicating that the overall structure remains largely unchanged.

  11. Synthesis and characterization of a NaSICON series with general formula Na2.8Zr2-ySi1.8-4yP1.2+4yO12 (0=

    International Nuclear Information System (INIS)

    In this work, we present the synthesis and the characterization of ionic conducting ceramics of NaSICON-type (Natrium super ionic conductor). The properties of this ceramic make it suitable for use in electrochemical devices. These solid electrolytes can be used as sensors for application in the manufacturing of potentiometric gas sensors, for the detection of pollutant emissions and for environment control. The family of NaSICON that we studied has as a general formula Na2.8Zr2-ySi1.8-4yP1.2+4yO12 with 0=2.8Zr1.775Si0.9P2.1O12 composition

  12. Structural modal reanalysis for large, simultaneous and multiple type modifications

    Science.gov (United States)

    Jian-jun, He; Xiang-zi, Chen; Bin, Xu

    2015-10-01

    Eigenvalue problem is widely used to investigate the dynamic characteristics of large and complex structure. For finite element models, iterative solvers are needed to precisely calculate eigenvectors and eigenvalues. However, in cases such as large-scale reanalysis studies, or optimization design of huge structure, computational cost can quickly become too time consuming. This paper focus on the structural modal reanalysis for large and multiple modifications (including simultaneous boundary, topology and type modifications), which can greatly affect the eigen-modes of the modified structures. The proposed methods are based on the results from the modal analysis of the original structure, and the stiffness and mass matrix of the modified structures. A highly approximate eigensolution are generated by the proposed method, which is combined the newly added DOF (Degrees of Freedom) condensation, ICMO strategy (Independent and Coupling Mass Orthogonalization) with the Rayleigh-Ritz analysis. The numerical examples show that the proposed method is efficient with high precision even when large and multiple type modifications of the structural topology, boundary and type are made simultaneously.

  13. Structure of Adeno-Associated Virus Type 4

    OpenAIRE

    Padron, Eric; Bowman, Valorie; Kaludov, Nikola; Govindasamy, Lakshmanan; Levy, Hazel; Nick, Phillip; McKenna, Robert; Muzyczka, Nicholas; John A. Chiorini; Baker, Timothy S.; Agbandje-McKenna, Mavis

    2005-01-01

    Adeno-associated virus (AAV) is a member of the Parvoviridae, belonging to the Dependovirus genus. Currently, several distinct isolates of AAV are in development for use in human gene therapy applications due to their ability to transduce different target cells. The need to manipulate AAV capsids for specific tissue delivery has generated interest in understanding their capsid structures. The structure of AAV type 4 (AAV4), one of the most antigenically distinct serotypes, was determined to 1...

  14. Structural inheritance in cast 30KhGNM-type steel

    International Nuclear Information System (INIS)

    Structural inheritance in the cast 30KhGNM-type steel depending on the heating rate and the temperature of preliminary tempering is investigated. When eating the cast steel with a beinite structure at the rate of 1-150 deg/min, the restoration of austenite grain and the following recrystallization due to the phase cold work, are observed. Slow heating from room temperature or preliminary tempering hinder grain restoration during heating. A non-monotonous effect of tempering temperature on the structural inheritance is established which can be connected with the kinetics of decomposition of residual austenite in steel

  15. Crystal structure of clathrates of Hofmann dma-type

    International Nuclear Information System (INIS)

    Seven new clathrates Cd(DMA)2Ni(CN)4·xG (x=1, G=aniline, 2,3-xylidine, 2,4-xylidine, 2,5-xylidine, 2,6-xylidine, 3,5-xylidine, and x=2, G=2,4,6-trimethylaniline) of Hofmann type are synthesized by amine substitution for dimethylamine (DMA). On the base of x-ray diffraction data it is shown that geometry of guest molecule in cage-like hollow determines the structure of the host and crystal structure of clathrates. Two-dimension metallocomplex of the host of studied clathrates is characterized by elastic folded structure appearing as a result of angular deformation of bond between Cd atoms and host cyanide bridge. Guest molecule orientation is fixed by hydrogen bond. Structural elasticity of the host complex directs to differences in crystal structure of clathrates formed and to considerable variety of incorporated guests

  16. Harmonic structure of type IIIb and III bursts

    International Nuclear Information System (INIS)

    A decameter solar radio storm of type IIIb and III bursts has been analysed, using single frequency records at frequencies 12.5 and 25.0 MHz. Several kinds of burst associations are classified. As a result it is shown that in double oblique burst-traces of type IIIb+III on the frequency-time plane the type III burst is shifted by an octave above the type IIIb burst at any moment of the IIIb+III pair's lifetime. In particular the harmonic structure of the spectrum is peculiar to the event of type IIIb+III in the initial and the final stages. This property of the pair is clear if the type IIIb and III radiations occur at the fundamental coronal plasma frequency and its harmonic respectively. On the other hand, if it is assumed that a type IIIb burst is the precursor of a type III one, there is no reason why the two bursts should be harmonically related. (Auth.)

  17. A Quasi-Type-1 Phase-Locked Loop Structure

    DEFF Research Database (Denmark)

    Golestan, Saeed; Fernandez, Francisco Daniel Freijedo

    2014-01-01

    The grid voltage phase and frequency are crucial information in control of most grid connected power electronic based equipment. Most often, a phase-locked loop (PLL) is employed for this purpose. A PLL is a closed-loop feedback control system that the phase of its output signal is related to the phase of its input signal. Arguably, the simplest PLL is a type-1 PLL. The type-1 PLLs are characterized by having only one integrator in their control loop and therefore having a high stability margin. However, they suffer from a serious drawback: they cannot achieve zero average steady-state phase-error in the presence of frequency drifts. To overcome this drawback of type-1 PLLs, and at the same time, to achieve a fast dynamic response and high filtering capability, a modified PLL structure is proposed in this letter. The proposed PLL has a similar structure to a type-1 PLL, but from the control point of view is a type-2 control system. For this reason, it is called the quasi-type-1 PLL (QT1-PLL). The effectiveness of the proposed PLL is confirmed through simulation and experimental results and comparison with standard PLLs.

  18. Atomic structures of icosahedral phases of type F and dislocations

    International Nuclear Information System (INIS)

    The object of this thesis is the study of atomic structures of icosahedral phases of type F and their dislocations. In this study, we have first built a prototypical structure that describes the already known F type icosahedral phases. In order to check it we synthesized some of the new compositions predicted by this model. This synthesis led to the discovery of two new quasi-periodical phases of the stoichiometry Al66,08Cu21,35Mn8,29Fe4,28. One of these phases is icosahedral (metastable) of type F and the other one is decagonal (stable). A F-IQC phase is present on these compounds that have a different composition with respect to the ones already studied for the system (Al,Pd,Fe). Globally, these experimental results on new icosahedral phases allowed to prove the viability of the model: on the three samples of new composition, two of them have shown the existence of icosahedral phases of type F and the third one has given a decagonal phase, in relation of canonical orientation with the icosahedral metastable phase (10-fold axis parallel with 5-fold axis). Using this reliable model, we have been able to introduce dislocations. We could thus provide the geometry of dislocations (outside the dislocation core) at atomic scale for F-IQC phases. On this structure we have also identified the distributions of phasons and given some elements of answer for the global dislocations moves. (author)

  19. Equipment and building structures ageing management for WWER type NPPs

    International Nuclear Information System (INIS)

    This report presents the working group 'Equipment and building structures ageing management for WWER type NPPs' activities. The analysis of experience in ageing management, recommendations for regulatory guidelines on ageing management, investigation of case studies, definition suitable communication channels among regulators for ageing related data are given. Analyses of water chemistry, inspection data (safety margins criteria), plugging criteria, volume and time of ECT implementation in all WWER countries are presented. The results of Working group activity show that it is advisable to concentrate efforts on: set up the permanent communication channel among regulators, collection of regulatory criteria for WWER type NPP key components based on understanding of ageing mechanisms and data collection

  20. Extended, regular HI structures around early-type galaxies

    OpenAIRE

    OOsterloo, T.; Morganti, R.; Sadler, E. M; van der Hulst, J. M.; Serra, P.

    2007-01-01

    We discuss the morphology and kinematics of the HI of a sample of 30 southern gas-rich early-type galaxies selected from the HI Parkes All-Sky Survey (HIPASS). This is the largest collection of high-resolution HI data of a homogeneously selected sample. Given the sensitivity of HIPASS, these galaxies represent the most HI-rich early-type galaxies. In two-thirds of the galaxies, we find the HI to be in a large, regular disk- or ring-like structure that in some cases is stro...

  1. Magnetic mirror structure for testing shell-type quadrupole coils

    Energy Technology Data Exchange (ETDEWEB)

    Andreev, N.; Barzi, E.; Bossert, R.; Chlachidze, G.; Kashikhin, V.S.; Kashikhin, V.V.; Lamm, M.J.; Nobrega, F.; Novitski, I.; Tartaglia, N.; Turrioni, D.; /Fermilab

    2009-10-01

    This paper presents magnetic and mechanical designs and analyses of the quadrupole mirror structure to test single shell-type quadrupole coils. Several quadrupole coils made of different Nb{sub 3}Sn strands, cable insulation and pole materials were tested using this structure at 4.5 and 1.9 K. The coils were instrumented with voltage taps, spot heaters, temperature sensors and strain gauges to study their mechanical and thermal properties and quench performance. The results of the quadrupole mirror model assembly and test are reported and discussed.

  2. Effects of structure type on viscoelastic properties of geosynthetics

    Directory of Open Access Journals (Sweden)

    I.I. Loginova

    2015-06-01

    Full Text Available This work presents a study on tensile properties of geosynthetic materials. There were investigated six samples of geofabrics and geogrids with different structures including woven geotextile fabrics, nonwoven geotextile fabrics, warp-knitted geogrids and extruded geogrid. The study determined tensile properties of geosynthetics including tensile strength, strain at the maximum load and tensile load at a specified strain. The authors carried out creep and relaxation tests. It was found that the structure type significantly affects viscoelastic properties of geosynthetics materials. The article presents some results of numerous tests, which may be used to pre-select geosynthetics materials.

  3. The waveguide structures of the inverted-rib type

    Science.gov (United States)

    Rogozi?ski, R.; Tyszkiewicz, C.; Karasi?ski, P.

    2014-05-01

    This paper presents an analysis of the possibilities of producing waveguide structures of the inverted-rib type. Such structures can be produced on the basis of planar gradient strip waveguides (channel waveguides) produced in a glass substrate by the ion exchange method. The glass surface is then covered with a thin uniform optical layer with a high refractive index. The thickness of this layer is less than the cut off thickness for the used wavelength. The wave propagation is therefore possible in the gradient area only. The homogeneous sensitivity of such waveguides is much greater than in case of single-mode waveguides without a uniform layer. The paper presents the calculations of homogeneous sensitivity for single-mode waveguides of the rib type, the inverted rib waveguides and the gradient waveguides. The use of single-mode inverted rib waveguides in the design of the planar interferometer in the Young configuration was proposed.

  4. Robust Structural Optimization Using Gauss-type Quadrature Formula

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Hoon; Seo, Ki Seog; Chen, Shikui; Chen, Wei [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2009-08-15

    In robust design, the mean and variance of design performance are frequently used to measure the design performance and its robustness under uncertainties. In this paper, we present the Gauss-type quadrature formula as a rigorous method for mean and variance estimation involving arbitrary input distributions and further extend its use to robust design optimization. One dimensional Gauss-type quadrature formula are constructed from the input probability distributions and utilized in the construction of multidimensional quadrature formula such as the tensor product quadrature (TPQ) formula and the univariate dimension reduction (UDR) method. To improve the efficiency of using it for robust design optimization, a semi-analytic design sensitivity analysis with respect to the statistical moments is proposed. The proposed approach is applied to a simple bench mark problems and robust topology optimization of structures considering various types of uncertainty.

  5. Robust structural optimization using Gauss-type quadrature formula

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Sang Hoon; Seo, Ki Seog [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Chen, Shikui; Chen, Wei [Northwestern University, Illinois (United States)

    2009-07-01

    In robust design, the mean and variance of design performance are frequently used to measure the design performance and its robustness under uncertainties. In this paper, we present the Gauss-type quadrature formula as a rigorous method for mean and variance estimation involving arbitrary input distributions and further extend its use to robust design optimization. One dimensional Gauss-type quadrature formula are constructed from the input probability distributions and utilized in the construction of multidimensional quadrature formula such as the Tensor Product Quadrature (TPQ) formula and the Univariate Dimension Reduction (UDR) method. To improve the efficiency of using it for robust design optimization, a semi-analytic design sensitivity analysis with respect to the statistical moments is proposed. The proposed approach is applied to a simple bench mark problems and robust topology optimization of structures considering various types of uncertainty.

  6. Babel Fortran 2003 Binding for Structured Data Types

    Energy Technology Data Exchange (ETDEWEB)

    Muszala, S; Epperly, T; Wang, N

    2008-05-02

    Babel is a tool aimed at the high-performance computing community that addresses the need for mixing programming languages (Java, Python, C, C++, Fortran 90, FORTRAN 77) in order to leverage the specific benefits of those languages. Scientific codes often rely on structured data types (structs, derived data types) to encapsulate data, and Babel has been lacking in this type of support until recently. We present a new language binding that focuses on their interoperability of C/C++ with Fortran 2003. The new binding builds on the existing Fortran 90 infrastructure by using the iso-c-binding module defined in the Fortran 2003 standard as the basis for C/C++ interoperability. We present the technical approach for the new binding and discuss our initial experiences in applying the binding in FACETS (Framework Application for Core-Edge Transport Simulations) to integrate C++ with legacy Fortran codes.

  7. The Three-Dimensional Structural Basis of Type II Hyperprolinemia

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Dhiraj; Singh, Ranjan K.; Moxley, Michael A.; Henzl, Michael T.; Becker, Donald F.; Tanner, John J. (UNL); (UMC)

    2012-08-31

    Type II hyperprolinemia is an autosomal recessive disorder caused by a deficiency in {Delta}{sup 1}-pyrroline-5-carboxylate dehydrogenase (P5CDH; also known as ALDH4A1), the aldehyde dehydrogenase that catalyzes the oxidation of glutamate semialdehyde to glutamate. Here, we report the first structure of human P5CDH (HsP5CDH) and investigate the impact of the hyperprolinemia-associated mutation of Ser352 to Leu on the structure and catalytic properties of the enzyme. The 2. 5-{angstrom}-resolution crystal structure of HsP5CDH was determined using experimental phasing. Structures of the mutant enzymes S352A (2.4 {angstrom}) and S352L (2.85 {angstrom}) were determined to elucidate the structural consequences of altering Ser352. Structures of the 93% identical mouse P5CDH complexed with sulfate ion (1.3 {angstrom} resolution), glutamate (1.5 {angstrom}), and NAD{sup +} (1.5 {angstrom}) were determined to obtain high-resolution views of the active site. Together, the structures show that Ser352 occupies a hydrophilic pocket and is connected via water-mediated hydrogen bonds to catalytic Cys348. Mutation of Ser352 to Leu is shown to abolish catalytic activity and eliminate NAD{sup +} binding. Analysis of the S352A mutant shows that these functional defects are caused by the introduction of the nonpolar Leu352 side chain rather than the removal of the Ser352 hydroxyl. The S352L structure shows that the mutation induces a dramatic 8-{angstrom} rearrangement of the catalytic loop. Because of this conformational change, Ser349 is not positioned to interact with the aldehyde substrate, conserved Glu447 is no longer poised to bind NAD{sup +}, and Cys348 faces the wrong direction for nucleophilic attack. These structural alterations render the enzyme inactive.

  8. Type II functional response for continuous, physiologically structured models.

    Science.gov (United States)

    Logan, J David; Ledder, Glenn; Wolesensky, William

    2009-07-21

    The goal of this work is to formulate a general Holling-type functional, or behavioral, response for continuous physiologically structured populations, where both the predator and the prey have physiological densities and certain rules apply to their interactions. The physiological variable can be, for example, a development stage, weight, age, or a characteristic length. The model leads to a Fredholm integral equation for the functional response, and, when inserted into population balance laws, it produces a coupled system of partial differential-integral equations for the two species, with a nonlocal integral term that arises from rules of interaction in the functional response. The general model is, typically, analytically intractable, but specialization to a structured prey-unstructured predator model leads to some analytic results that reveal interesting and unexpected dynamics caused by the presence of size-dependent handling times in the functional response. In this case, steady-states are shown to exist over long times, similar to the stable age-structure solutions for the McKendick-von Foerster model with exponential growth rates determined by the Euler-Lotka equation. But, for type II responses, there are early transient oscillations in the number of births that bifurcate in a few generations into either the decaying or growing steady-state. The bifurcation parameter is the initial level of prey. This special case is applied to a problem of the biological control of a structured pest population (e.g., aphids) by a predator (e.g., lady beetles). PMID:19362565

  9. Temperature Induced Structural Phase Transitions in Chalcopyrite Type Compound Semiconductors

    International Nuclear Information System (INIS)

    Full text : Multinary chalcogenides like Cu(In,Ga)(S,Se)2 are compound semiconductors suitable for applications in thin film photovoltaics. These compounds crystallize in a tetragonal chalcopyrite type structure, which can be described as a ccp array of chalcogen atoms, with metal atoms occupying one half of the tetrahedral voids. The chalcopyrites Cu(In,Ga)(Se,S)2 undergo a temperature dependent structural phase transition from the chalcopyrite to the sphalerite type structure. For CuInS2 and CuInSe2 it is a sharp orderdisorder phase transition, which occurs within a small temperature range of about 10 K. The character of this phase transition is dominated by an increasing Cu-In anti-site occupancy. On the other hand, in CuGaS2 no temperature dependent structural phase transition occurs. The phase transition in CuGaSe2 is characterized by the co-existence of a tetragonal and a cubic phase. Recently this study was extended to the Cu(In,Ga)S2 and Cu(In,Ga)Se2 mixed crystals. This presentation will give a comparative discussion of the structural phase transition in ternary and quaternary chalcopyrites. The basis for our investigations were in-situ high temperature powder diffraction experiments using synchrotron X-rays and were performed at the European Synchrotron Radiation Facility (ESRF), Grenoble, at the high energy beamline ID15B in the temperature range from room temperature to 1100 degrees Cesium. The data were analyzed in detail by the Rietveld refinement method to determine lattice parameters, the anion position and cation site occupancies. The presentation will give an overview of the structural phase transitions observed in these compound semiconductors. The differences between samples with various In/(In+Ga) ratios (from 1 to 0) will be pointed out, concerning not only the transition temperature, but primarily the character of the phase transition, the order parameter, its critical behaviour and universality

  10. The internal structure of the Sun and solar type stars

    International Nuclear Information System (INIS)

    Our understanding of the internal structure of the Sun and solar type stars has been undermined by recent observations. In this paper some of the puzzles and possible resolutions are considered; the solar neutrino problem, lithium and beryllium abundance, rotation and calcium emission, variation of the solar constant, solar oscillations and the solar convective zone. The picture that emerges in one of confusion, and so it should be since we have no idea of what is going on inside the Sun and a fortiori of what is going on inside other stars. (Auth.)

  11. The primary structure of cassowary (Casuarius casuarius) goose type lysozyme.

    Science.gov (United States)

    Thammasirirak, Sompong; Torikata, Takao; Takami, Kazutoshi; Murata, Koichi; Araki, Tomohiro

    2002-01-01

    The complete amino acid sequence of cassowary (Casuarius casuarius) goose type lysozyme was analyzed by direct protein sequencing of peptides obtained by cleavage with trypsin, V8 protease, chymotrypsin, lysyl endopeptidase, and cyanogen bromide. The N-terminal residue of the enzyme was deduced to be a pyroglutamate group by analysis with a LC/MS/MS system equipped with the oMALDI ionization source, and then confirmed by a glutamate aminopeptidase enzyme. The blocked N-terminal is the first reported in this enzyme group. The positions of disulfide bonds in this enzyme were chemically identified as Cys4-Cys60 and Cys18-Cys29. Cassowary lysozyme was proved to consist of 185 amino acid residues and had a molecular mass of 20408 Da calculated from the amino acid sequence. The amino acid sequence of cassowary lysozyme compared to that of reported G-type lysozymes had identities of 90%, 83%, and 81%, for ostrich, goose, and black swan lysozymes, respectively. The amino acid substitutions at PyroGlu1, Glu19, Gly40, Asp82, Thr102, Thr156, and Asn167 were newly detected in this enzyme group. The substituted amino acids that might contribute to substrate binding were found at subsite B (Asn122Ser, Phe123Met). The amino acid sequences that formed three alpha-helices and three beta-sheets were completely conserved. The disulfide bond locations and catalytic amino acid were also strictly conserved. The conservation of the three alpha-helices structures and the location of disulfide bonds were considered to be important for the formation of the hydrophobic core structure of the catalytic site and for maintaining a similar three-dimensional structure in this enzyme group. PMID:11866097

  12. Structural trends in off stoichiometric chalcopyrite type compound semiconductors

    International Nuclear Information System (INIS)

    Energy supply is one of the most controversial topics that are currently discussed in our global community. Most of the energy delivered to the customer today has its origin in fossil and nuclear power plants. Indefinable risks and the radioactive waste repository problem of the latter as well as the global scarcity of fossil resources cause the renewable energies to grow more and more important for achieving sustainability. The main renewable energy sources are wind power, hydroelectric power and solar energy. On the photovoltaic (PV) market different materials are competing as part of different kinds of technologies, with the largest contribution still coming from wafer based crystalline silicon solar cells (95 %). Until now thin film solar cells only contribute a small portion to the whole PV market, but large capacities are under construction. Thin film photovoltaic shows a number of advantages in comparison to wafer based crystalline silicon PV. Among these material usage and production cost reduction are two prominent examples. The type of PV materials, which are analyzed in this work, are high potential compounds that are widely used as absorber layer in thin film solar cells. These are compound semiconductors of the type CuBIIICVI2 (BIII = In, Ga and CVI = Se, S). Several years of research have already gone into understanding the efficiency limiting factors for solar cell devices fabricated from this compound. Most of the studies concerning electronic defects are done by spectroscopic methods mostly performed using thin films from different kinds of synthesis, without any real knowledge regarding the structural origin of these defects. This work shows a systematic fundamental structural study of intrinsic point defects that are present within the material at various compositions in CuBIIICVI2 compound semiconductors. The study is done on reference powder samples with well determined chemical composition and using advanced diffraction techniques, such as neutron and synchrotron X-ray diffraction. The results show that the main existing defects are found to be copper vacancies and BIIICu anti-site defects. Type and concentrations vary with the composition. It is demonstrated that, when assuming spontaneous formation of electrically neutral defect complexes made of these isolated point defects, the density of cationic point defects is reduced by an order of magnitude. This explains why the existence of native cationic point defects may not be the main efficiency limiting factor in thin film solar cells built with a CuBIIICVI2 absorber. This pinpoints why the mere presence of native cationic point defects does probably not suffice as main efficiency limiting factor in thin film solar cells based on CuBIIICVI2-type absorbers.

  13. Structure of the atmosphere of late-type stars

    International Nuclear Information System (INIS)

    A method of calculation of model atmospheres of late-type stars is described. The model atmospheres have been constructed for effective temperature Tsub(e)=2500, 3000, 3500, 4000, 4500 and 5785 K at solar chemical composition and surface gravities log g = 0.0, 1.0, 2.0, 3.0, 4.0 and 5.0 based on LTE and a plane-parallel horizontally homogeneous structure. Opacity due to H, H- and H2- was taken into account. The equation of state includes 10 metals and H2, H2- and H2+ molecules. The results are compared with those published elsewhere. A satisfactory agreement is obtained for Tsub(e) > 3000 K

  14. Electronic structure of p type Delta doped systems

    International Nuclear Information System (INIS)

    We summarize of the results obtained for the electronic structure of quantum wells that consist in an atomic layer doped with impurities of p type. The calculations are made within the frame worth of the wrapper function approach to independent bands and with potentials of Hartree. We study the cases reported experimentally (Be in GaAs and B in Si). We present the levels of energy, the wave functions and the rate of the electronic population between the different subbands, as well as the dependence of these magnitudes with the density of impurities in the layer. The participation of the bans of heavy holes is analysed, light and split-off band in the total electronic population. The effect of the temperature is discussed and we give a possible qualitative explanation of the experimental optical properties. (Author)

  15. Gradient type optimization methods for electronic structure calculations

    CERN Document Server

    Zhang, Xin; Wen, Zaiwen; Zhou, Aihui

    2013-01-01

    The density functional theory (DFT) in electronic structure calculations can be formulated as either a nonlinear eigenvalue or direct minimization problem. The most widely used approach for solving the former is the so-called self-consistent field (SCF) iteration. A common observation is that the convergence of SCF is not clear theoretically while approaches with convergence guarantee for solving the latter are often not competitive to SCF numerically. In this paper, we study gradient type methods for solving the direct minimization problem by constructing new iterations along the gradient on the Stiefel manifold. Global convergence (i.e., convergence to a stationary point from any initial solution) as well as local convergence rate follows from the standard theory for optimization on manifold directly. A major computational advantage is that the computation of linear eigenvalue problems is no longer needed. The main costs of our approaches arise from the assembling of the total energy functional and its grad...

  16. Reactor core lower structural members of PWR type reactor

    International Nuclear Information System (INIS)

    In the PWR type reactor of the present invention, a flow rate distribution of coolants in a lower plenum is unified, so that the reactor core is cooled uniformly as much as possible and fluid exciting vibration is reduced. Namely, the PWR type reactor has a large number of instrumentation guide tubes extending in parallel with each other between a semispherical shell-like bottom plate and a reactor core lower support plate of the reactor container. A connection support plate connects the instrumentation guide tubes so as to support them. The lower connection portion near the bottom plate of the reactor container is adapted to have a circular external shape, an annular region having no perforation hole is formed at the outer circumference thereof. It is disposed closer to the semispherical bottom plate thus constituting reactor lower structural members. With such a constitution, coolants flown down in an annular descending flow channel collide against the annular region having no perforation hole at the lower connection support plate, then form a uniform inward horizontal stream and join in a relatively wide region. As a result, uniform upwarding rate distribution can be obtained. Accordingly, local hot spots are not caused thereby enabling to operate the reactor efficiently. (I.S.)

  17. Structure, Function, and Assembly of Type 1 Fimbriae

    Science.gov (United States)

    Knight, Stefan D.; Bouckaert, Julie

    Bacterial infections constitute a major global health problem, acutely accentuated by the rapid spread of antibiotic resistant bacterial strains. The widespread need for bacteria to attach - adhere - to target cells before they can initiate an infection may be used to advantage by targeting the bacterial adhesion tools such as pili and fimbriae for development of novel anti-bacterial vaccines and drugs. Type 1 fimbriae are widely expressed by Escherichia coli. and are used by uropathogenic strains to mediate attachment to specific niches in the urinary tract. These fimbriae belong to a class of fibrillar adhesion organelles assembled through the chaperone/usher pathway, one of the terminal branches of the general secretion pathway in Gram-negative bacteria. Our understanding of the assembly, structure and function of these structures has evolved significantly over the last decade. Here, we summarize current understanding of the function and biogenesis of fibrillar adhesion organelles, and provide some examples of recent progress towards interfering with bacterial adhesion as a means to prevent infection.

  18. Magnetic Structure of Rapidly Rotating FK Comae-Type Coronae

    CERN Document Server

    Cohen, O; Kashyap, V L; Korhonen, H; Elstner, D; Gombosi, T I

    2010-01-01

    We present a three-dimensional simulation of the corona of an FK Com-type rapidly rotating G giant using a magnetohydrodynamic model that was originally developed for the solar corona in order to capture the more realistic, non-potential coronal structure. We drive the simulation with surface maps for the radial magnetic field obtained from a stellar dynamo model of the FK Com system. This enables us to obtain the coronal structure for different field topologies representing different periods of time. We find that the corona of such an FK Com-like star, including the large scale coronal loops, is dominated by a strong toroidal component of the magnetic field. This is a result of part of the field being dragged by the radial outflow, while the other part remains attached to the rapidly rotating stellar surface. This tangling of the magnetic field,in addition to a reduction in the radial flow component, leads to a flattening of the gas density profile with distance in the inner part of the corona. The three-dim...

  19. Type IIA orientifolds on SU(2)-structure manifolds

    International Nuclear Information System (INIS)

    We investigate the possible supersymmetry-preserving orientifold projections of type IIA string theory on a six-dimensional background with SU(2)-structure. We find two categories of projections which preserve half of the low-energy supersymmetry, reducing the effective theory from an N=4 supergravity theory, to an N=2 supergravity. For these two cases, we impose the projection on the low-energy spectrum and reduce the effective N=4 supergravity action accordingly. We can identify the resulting gauged N=2 supergravity theory and bring the action into canonical form. We compute the scalar moduli spaces and characterize the gauged symmetries in terms of the geometry of these moduli spaces. Due to their origin in N=4 supergravity, which is a highly constrained theory, the moduli spaces are of a very simple form. We find that, for suitable background manifolds, isometries in all scalar sectors can become gauged. The obtained gaugings share many features with those of N=2 supergravities obtained previously from other G-structure compactifications. (orig.)

  20. Type IIA orientifolds on SU(2)-structure manifolds

    Energy Technology Data Exchange (ETDEWEB)

    Danckaert, Thomas

    2010-11-15

    We investigate the possible supersymmetry-preserving orientifold projections of type IIA string theory on a six-dimensional background with SU(2)-structure. We find two categories of projections which preserve half of the low-energy supersymmetry, reducing the effective theory from an N=4 supergravity theory, to an N=2 supergravity. For these two cases, we impose the projection on the low-energy spectrum and reduce the effective N=4 supergravity action accordingly. We can identify the resulting gauged N=2 supergravity theory and bring the action into canonical form. We compute the scalar moduli spaces and characterize the gauged symmetries in terms of the geometry of these moduli spaces. Due to their origin in N=4 supergravity, which is a highly constrained theory, the moduli spaces are of a very simple form. We find that, for suitable background manifolds, isometries in all scalar sectors can become gauged. The obtained gaugings share many features with those of N=2 supergravities obtained previously from other G-structure compactifications. (orig.)

  1. Structural phase transitions of rare earth monophosphides with NaCl-type structure under high pressures

    International Nuclear Information System (INIS)

    Rare earth monophosphides REP (RE=La, Ce, Pr, Nd, Sm, Gd, Tb, Tm and Yb) crystallize in a NaCl-type structure at ambient pressure. Using synchrotron radiation X-ray diffractions of REP have been studied up to about 60 GPa at room temperature. All phosphides are found to undergo structural phase transitions at high pressures. The high pressure phases of LaP, PrP and NdP can be assigned to be a tetragonal structure, which can be seen as the distorted CsCl-type structure. The pressure-induced phase transitions of SmP, GdP, TbP, TmP and YbP occur at around 35, 40, 38, 53 and 51 GPa, respectively. The structure of the high pressure phases is unknown. X-ray diffraction patterns of the compounds with many f-electrons become more complex at high pressure. It is expected that 4f-electrons in rare earth atoms influence the structure of the high pressure phases. (author)

  2. Deformations of complex structures on Riemann surfaces and integrable structures in Whitham type hierarchies

    CERN Document Server

    Odesskii, Alexander

    2015-01-01

    We obtain variational formulas for holomorphic objects on Riemann surfaces with respect to arbitrary local coordinates on moduli space of complex structures. These formulas are written in terms of a canonical object on moduli space which corresponds to the pairing between the space of quadratic differentials and the tangent space to moduli space. This canonical object satisfies certain commutation relations which appear to be the same as ones emerged in integrability theory of Whitham type hierarchies. Driven by this observation, we develop the theory of Whitham type hierarchies integrable by hydrodynamic reductions as a theory of certain differential-geometric objects.

  3. Structural trends in off stoichiometric chalcopyrite type compound semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Stephan, Christiane

    2011-03-15

    Energy supply is one of the most controversial topics that are currently discussed in our global community. Most of the energy delivered to the customer today has its origin in fossil and nuclear power plants. Indefinable risks and the radioactive waste repository problem of the latter as well as the global scarcity of fossil resources cause the renewable energies to grow more and more important for achieving sustainability. The main renewable energy sources are wind power, hydroelectric power and solar energy. On the photovoltaic (PV) market different materials are competing as part of different kinds of technologies, with the largest contribution still coming from wafer based crystalline silicon solar cells (95 %). Until now thin film solar cells only contribute a small portion to the whole PV market, but large capacities are under construction. Thin film photovoltaic shows a number of advantages in comparison to wafer based crystalline silicon PV. Among these material usage and production cost reduction are two prominent examples. The type of PV materials, which are analyzed in this work, are high potential compounds that are widely used as absorber layer in thin film solar cells. These are compound semiconductors of the type CuB{sup III}C{sup VI}{sub 2} (B{sup III} = In, Ga and C{sup VI} = Se, S). Several years of research have already gone into understanding the efficiency limiting factors for solar cell devices fabricated from this compound. Most of the studies concerning electronic defects are done by spectroscopic methods mostly performed using thin films from different kinds of synthesis, without any real knowledge regarding the structural origin of these defects. This work shows a systematic fundamental structural study of intrinsic point defects that are present within the material at various compositions in CuB{sup III}C{sup VI}{sub 2} compound semiconductors. The study is done on reference powder samples with well determined chemical composition and using advanced diffraction techniques, such as neutron and synchrotron X-ray diffraction. The results show that the main existing defects are found to be copper vacancies and B{sup III}{sub Cu} anti-site defects. Type and concentrations vary with the composition. It is demonstrated that, when assuming spontaneous formation of electrically neutral defect complexes made of these isolated point defects, the density of cationic point defects is reduced by an order of magnitude. This explains why the existence of native cationic point defects may not be the main efficiency limiting factor in thin film solar cells built with a CuB{sup III}C{sup VI}{sub 2} absorber. This pinpoints why the mere presence of native cationic point defects does probably not suffice as main efficiency limiting factor in thin film solar cells based on CuB{sup III}C{sup VI}{sub 2}-type absorbers.

  4. Electronic structure of binary phases with a hexagonal WC type structure

    International Nuclear Information System (INIS)

    Electronic structure and interatomic interactions in known binary metal-nonmetal phases with hexagonal (D3h1 symmetry) structure of WC type are studied by self-consistent full-potential method of muffin-tin orbitals. For investigated compounds of d-metals with 2p-nonmetals (RuB, IrB, WC, WN, TaN, TiO) total and partial densities of state and cohesion energies are obtained. On their base relative chemical stability and some physicochemical properties of phases considered are discussed

  5. Crystal structure of wild-type human procathepsin K.

    Science.gov (United States)

    Sivaraman, J; Lalumière, M; Ménard, R; Cygler, M

    1999-02-01

    Cathepsin K is a lysosomal cysteine protease belonging to the papain superfamily. It has been implicated as a major mediator of osteoclastic bone resorption. Wild-type human procathepsin K has been crystallized in a glycosylated and a deglycosylated form. The latter crystals diffract better, to 3.2 A resolution, and contain four molecules in the asymmetric unit. The structure was solved by molecular replacement and refined to an R-factor of 0.194. The N-terminal fragment of the proregion forms a globular domain while the C-terminal segment is extended and shows substantial flexibility. The proregion interacts with the enzyme along the substrate binding groove and along the proregion binding loop (residues Ser138-Asn156). It binds to the active site in the opposite direction to that of natural substrates. The overall binding mode of the proregion to cathepsin K is similar to that observed in cathepsin L, caricain, and cathepsin B, but there are local differences that likely contribute to the specificity of these proregions for their cognate enzymes. The main observed difference is in the position of the short helix alpha3p (67p-75p), which occupies the S' subsites. As in the other proenzymes, the proregion utilizes the S2 subsite for anchoring by placing a leucine side chain there, according to the specificity of cathepsin K toward its substrate. PMID:10048321

  6. Meta-analyses of structural regional cerebral effects in type 1 and type 2 diabetes.

    Science.gov (United States)

    Moulton, Calum D; Costafreda, Sergi G; Horton, Paul; Ismail, Khalida; Fu, Cynthia H Y

    2015-12-01

    Diabetes is associated with macrovascular and microvascular complications and is a major risk factor for neurological and psychiatric disorders, such as dementia and depression. Type 1 diabetes (T1DM) and type 2 diabetes (T2DM) have distinct etiologies and pathophysiological effects while sharing a common endpoint of persistent hyperglycemia. Neuroimaging studies in T1DM have revealed reductions in numerous regions, including the parahippocampal and occipital regions, while in T2DM there have been numerous reports of hippocampal atrophy. This meta-analysis aimed to identify consistent regional abnormalities in cerebral structures in T1DM and T2DM respectively, and also to examine the impact of potential confounds, including age, depression and vascular risk factors. Neuroimaging studies of both voxel-based morphometry (VBM) data and volumetric data were included. Ten T1DM studies (n?=?613 patients) and 23 T2DM studies (n?=?1364 patients) fulfilled inclusion criteria. The T1DM meta-analysis revealed reduced bilateral thalamus grey matter density in adults. The T2DM meta-analysis revealed reduced global brain volume and regional atrophy in the hippocampi, basal ganglia, and orbitofrontal and occipital lobes. Moreover, hippocampal atrophy in T2DM was not modified by hypertension, although there were more marked reductions in younger patients relative to healthy controls. In conclusion, T1DM and T2DM demonstrated distinct cerebral effects with generalised and specific target areas of grey matter reduction. Thalamic atrophy in T1DM may be a substrate of associated cognitive deficits. In T2DM, global cerebral atrophy may reflect atherosclerotic factors, while hippocampal atrophy was an independent effect providing a potential common neuropathological etiology for the comorbidity of T2DM with dementia and depression. PMID:25563229

  7. A Quasi-Type-1 Phase-Locked Loop Structure

    DEFF Research Database (Denmark)

    Golestan, Saeed; Fernandez, Francisco Daniel Freijedo; Vidal, Ana; Guerrero, Josep M.; Doval-Gandoy, Jesus

    2014-01-01

    phase of its input signal. Arguably, the simplest PLL is a type-1 PLL. The type-1 PLLs are characterized by having only one integrator in their control loop and therefore having a high stability margin. However, they suffer from a serious drawback: they cannot achieve zero average steady-state phase-error...

  8. The prolongation structure of the inhomogeneous equation of the reaction-diffusion type

    International Nuclear Information System (INIS)

    The inhomogeneous extension of equations of the reaction-diffusion type is investigated by means of the covariant prolongation structures theory. We construct the sl(2, R) x R(?(t)) prolongation structure for an inhomogeneous equation of the reaction-diffusion type and give the corresponding AKNS-type equations and the Baecklund transformation

  9. A New Type of Center Data Structure in Cloud Computing

    Directory of Open Access Journals (Sweden)

    Guo Xiaohui

    2014-01-01

    Full Text Available This study analyzes and summarizes new characteristics of Cloud Computing data center, a new network structure in the design of cloud computing data center is proposed, the concepts of Cloud Computing and data center are introduced. It analyzes three important issues deeply, the scalability and green energy issues of the data center are analyzed and it makes full consideration of new characteristics of Cloud Computing data center and presents a new data center network structure according to famous Koch Curve, the snow structure. It makes full account of the data center’s scalability and low proportion of switches and servers and can achieve routing within a shorter average path and smaller network overhead. In the study of snowflake structure of cloud computing data center network building methods are proposed and its properties are discussed, the simulation and experiments are performed to validate the performance of the structure.

  10. A New Type of Center Data Structure in Cloud Computing

    OpenAIRE

    Guo Xiaohui; Wei Jian Yu; Wang Beibei; Liyongqing

    2014-01-01

    This study analyzes and summarizes new characteristics of Cloud Computing data center, a new network structure in the design of cloud computing data center is proposed, the concepts of Cloud Computing and data center are introduced. It analyzes three important issues deeply, the scalability and green energy issues of the data center are analyzed and it makes full consideration of new characteristics of Cloud Computing data center and presents a new data center network structure according to f...

  11. Soil/structure interactions of eastern US type earthquakes

    International Nuclear Information System (INIS)

    This paper presents analyses and conclusions pertaining to the earthquake motions felt at Virgil C. Summer, Perry and Krsko nuclear power plants. Consideration is given to promote an improved understanding of these events, describe common characteristics, assess damage potential, and recommend operating procedures for similar future events. An easy-to-follow analytical investigation is performed to describe how the earthquakes recorded at Krsko may be influenced by soil/structure interaction including a few parametric studies to account for uncertainties in the soil properties. These consist of variations in the shear and compressional wave velocities and variations in the seismic wave environment in the form of arbitrarily oriented body waves or Rayleigh waves. The analysis takes into account nonlinearity of the soil material, radiation and hysteretic damping, ground-water table level, structural embedment, and structure/structure interaction. The analysis is based on state-of-the-art computer software, elaborate analysis techniques and simpler engineering approximations. Results of analysis show clear evidence of soil/structure interaction, nonlinear softening of the soil material and encouraging qualitative and quantitative agreement with the recorded measurements. The structural response motions display high rocking mode

  12. A Quasi-Type-1 Phase-Locked Loop Structure

    OpenAIRE

    Golestan, Saeed; Fernandez, Francisco Daniel Freijedo; Vidal, Ana; Guerrero, Josep M.; Doval-Gandoy, Jesus

    2014-01-01

    The grid voltage phase and frequency are crucial information in control of most grid connected power electronic based equipment. Most often, a phase-locked loop (PLL) is employed for this purpose. A PLL is a closed-loop feedbackcontrol system that the phase of its output signal is related to the phase of its input signal. Arguably, the simplest PLL is a type-1 PLL. The type-1 PLLs are characterized by having only one integrator in their control loop and therefore having a high stability margi...

  13. Structures of the Mating-Type Loci of Cordyceps takaomontana

    OpenAIRE

    Yokoyama, Eiji; Yamagishi, Kenzo; HARA, AKIRA

    2003-01-01

    Nucleotide sequences of the mating-type loci MAT1-1 and MAT1-2 of Cordyceps takaomontana were determined, which is the first such report for the clavicipitaceous fungi. MAT1-1 contains two mating-type genes, MAT1-1-1 and MAT1-1-2, but MAT1-1-3 could not be found. On the other hand, MAT1-2 has MAT1-2-1. A pseudogene of MAT1-1-1 is located next to MAT1-2.

  14. Well-formedness and typing rules for UML Composite Structures

    CERN Document Server

    Dragomir, Iulia

    2010-01-01

    Starting from version 2.0, UML introduced hierarchical composite structures, which are an expressive way of defining complex software architectures, but which have a very loosely defined semantics in the standard. In this paper we propose a set of consistency rules that disambiguate the meaning of UML composite structures. Our primary goal was to have an operational model of composite structures for the OMEGA UML profile, an executable profile dedicated to the formal specification and validation of real-time systems, developed in a past project to which we contributed. However, the rules and principles stated here are applicable to other hierarchical component models based on the same concepts, such as SysML. The presented ruleset is supported by an OCL formalization which is described in this report. This formalization was applied on different complex models for the evaluation and validation of the proposed principles.

  15. On Tanaka's Prolongation Procedure for Filtered Structures of Constant Type

    Directory of Open Access Journals (Sweden)

    Igor Zelenko

    2009-10-01

    Full Text Available We present Tanaka's prolongation procedure for filtered structures on manifolds discovered in [Tanaka N., J. Math. Kyoto. Univ. 10 (1970, 1-82] in a spirit of Singer-Sternberg's description of the prolongation of usual G-structures [Singer I.M., Sternberg S., J. Analyse Math. 15 (1965, 1-114; Sternberg S., Prentice-Hall, Inc., Englewood Cliffs, N.J., 1964]. This approach gives a transparent point of view on the Tanaka constructions avoiding many technicalities of the original Tanaka paper.

  16. Vortex-type elastic structured media and dynamic shielding

    CERN Document Server

    Brun, Michele; Movchan, Alexander B

    2012-01-01

    The paper addresses a novel model of metamaterial structure. A system of spinners has been embedded into a two-dimensional periodic lattice system. The equations of motion of spinners are used to derive the expression for the chiral term in the equations describing the dynamics of the lattice. Dispersion of elastic waves is shown to possess innovative filtering and polarization properties induced by the vortextype nature of the structured media. The related homogenised effective behavior is obtained analytically and it has been implemented to build a shielding cloak around an obstacle. Analytical work is accompanied by numerical illustrations.

  17. Structures in the fundamental plane of early-type galaxies

    CERN Document Server

    Fraix-Burnet, Didier; Chattopadhyay, Tanuka; Chattopadhyay, Asis Kumar; Davoust, Emmanuel

    2010-01-01

    The fundamental plane of early-type galaxies is a rather tight three-parameter correlation discovered more than twenty years ago. It has resisted a both global and precise physical interpretation despite a consequent number of works, observational, theoretical or using numerical simulations. It appears that its precise properties depend on the population of galaxies in study. Instead of selecting a priori these populations, we propose to objectively construct homologous populations from multivariate analyses. We have undertaken multivariate cluster and cladistic analyses of a sample of 56 low-redshift galaxy clusters containing 699 early-type galaxies, using four parameters: effective radius, velocity dispersion, surface brightness averaged over effective radius, and Mg2 index. All our analyses are consistent with seven groups that define separate regions on the global fundamental plane, not across its thickness. In fact, each group shows its own fundamental plane, which is more loosely defined for less diver...

  18. Structural and dielectric properties of perovskite-type artificial superlattices

    International Nuclear Information System (INIS)

    BaTiO3/SrTiO3, SrZrO3/SrTiO3 and BaTiO3/BaZrO3 artificial superlattices were fabricated by the molecular beam epitaxy process. X-ray diffraction (XRD) reciprocal space mapping measurement was performed using high-resolution XRD. In all artificial superlattices, the superlattices with the 10-periodic structure showed the clear satellite peaks in the XRD pattern and were mostly distorted in the direction of film thickness. Superlattices with the 10-periodic structure showed a high dielectric permittivity of ? r = 33,000 or artificially induced ferroelectricity. It was clarified that the anisotropic lattice distortion introduced by the strains due to the lattice mismatch was the origin of the unique dielectric characteristics of artificial superlattices

  19. Type of disturbance and ecological history determine structural stability

    OpenAIRE

    van der Wurff, A. W. G.; Kools, S.A.E.; Boivin, M. E. Y.; Brink, P.J., van den; Megen, H.H.B., van; Riksen, J. A. G.; Doroszuk, A.; Kammenga, J E

    2007-01-01

    This study aims to reveal whether complexity, namely, community and trophic structure, of chronically stressed soil systems is at increased risk or remains stable when confronted with a subsequent disturbance. Therefore, we focused on a grassland with a history of four centuries of patchy contamination. Nematodes were used as model organisms because they are an abundant and trophically diverse group and representative of the soil food web and ecosystem complexity. In a field survey, a relatio...

  20. Structural studies of different types of ferroelectric liquid crystalline substances.

    Czech Academy of Sciences Publication Activity Database

    Obadovi?, D.Ž.; Stojanovi?, M.; Bubnov, Alexej; Éber, N.; Cvetinov, M.; Vajda, A.

    2011-01-01

    Ro?. 35, ?. 1 (2011), s. 3-13. ISSN 1450-7404 R&D Projects: GA AV ?R IAA100100911; GA AV ?R(CZ) GA202/09/0047; GA ?R(CZ) GAP204/11/0723 Grant ostatní: RFASI(RU) 02.740.11.5166 Institutional research plan: CEZ:AV0Z10100520 Keywords : ferroelectric liquid crystals * phase transition * structure of liquid crystalline phases * molecular parameters Subject RIV: BM - Solid Matter Physics ; Magnetism

  1. Profiling of N-Type Dopants in Silicon Based Structures.

    Czech Academy of Sciences Publication Activity Database

    Hovorka, Miloš; Mika, Filip; Frank, Lud?k; Mikulík, P.

    Brno : ISI AS CR, 2009 - (Pokorná, Z.; Mika, F.), s. 14 ISBN 978-80-254-4535-8. [CJCS’09 - Czech-Japan- China Cooperative Symposium on Nanostructure of Advanced Materials and Nanotechnology /4./. Brno (CZ), 10.08.2009-14.08.2009] R&D Projects: GA ?R GP102/09/P543; GA AV ?R IAA100650803 Institutional research plan: CEZ:AV0Z20650511 Keywords : n-type substrate * SEM * PEEM * doping levels Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  2. Atlas of fine structures of dynamic spectra of solar type IV-dm and some type II radio bursts

    International Nuclear Information System (INIS)

    The author presents an atlas of spectral fine structures of solar radio bursts of types IV and II around 1 m wavelength, as obtained with a multichannel spectrograph at Dwingeloo. The structures form largely a collection of observations of these events during late 1968 through 1974, thus covering almost entirely the declining branch of solar cycle 20. The spectrograph has an extra enhanced contrast output with properties quite different from those of the commonly used swept frequency spectrographs. The corresponding instrumental characteristics and effects are discussed. A classification of fine structures and an analysis of their statistical properties and of those of the pertinent radio events are also given. (Auth.)

  3. Filamentary structures of the cosmic web and the nonlinear Schroedinger type equation

    International Nuclear Information System (INIS)

    We show that the filamentary type structures of the cosmic web can be modeled as solitonic waves by solving the reaction diffusion system which is the hydrodynamical analogous of the nonlinear Schroedinger type equation. We find the analytical solution of this system by applying the Hirota direct method which produces the dissipative soliton solutions to formulate the dynamical evolution of the nonlinear structure formation.

  4. Structure of a Kunitz-type potato cathepsin D inhibitor.

    Science.gov (United States)

    Guo, Jingxu; Erskine, Peter T; Coker, Alun R; Wood, Steve P; Cooper, Jonathan B

    2015-12-01

    Potato cathepsin D inhibitor (PDI) is a glycoprotein of 188 amino acids which can inhibit both the aspartic protease cathepsin D and the serine protease trypsin. Here we report the first X-ray structure of PDI at a resolution of 2.1Å showing that PDI adopts a ?-trefoil fold, which is typical of the Kunitz-family protease inhibitors, with the inhibitory loops protruding from the core. Possible reactive-site loops including one involving a unique disulphide and another involving a protruding 310 helix are identified and docking studies indicate the mode of action of this unusual bi-functional inhibitor. PMID:26542926

  5. Structural constraints on human immunodeficiency virus type 1 Nef function

    International Nuclear Information System (INIS)

    HIV-1 Nef is a multifunctional protein that exerts its activities through interactions with multiple cellular partners. Nef uses different domains and mechanisms to exert its functions including cell surface down-modulation of CD4 and MHC-I receptors and activation of the serine/threonine kinase PAK-2. We inserted tags at the C-terminus and proximal to the N-terminus of Nef and the effects on Nef's structure/function relationships were examined. We discovered significant defects in MHC-I down-modulation with the insertion of HA/FLAG tags at either region. We also found impaired PAK-2 activation with a C-terminal fusion with GFP. Interestingly, Nef-GFP and Nef-GH7 induced MHC-I down-modulation, suggesting that the negative charge of the HA/FLAG tag could contribute to the observed defect. Together, these observations highlight elements of Nef's functional complexity and demonstrate previously unsuspected structural requirements for PAK-2 activation and MHC-1 down-modulation in Nef's flexible N- and C-terminal regions

  6. Dowel-type fastener connections in timber structures subjected to short-term loading

    DEFF Research Database (Denmark)

    Lauritzen Jensen, J.

    1994-01-01

    Design of dowel-type fastener connections in framed timber structures usually involves a two-step analysis: determination of the distribution of the sectional forces, and design of the eccentrically loaded connections. This report presents an integrated model for design of framed timber structures with dowel-type fastener connections. A Finite-Element approach has been adopted. An element has been developed for modelling a plane group of dowel-type fasteners, taking due account of the material a...

  7. Types of Planning Structures of Small Historic Towns of Ukraine

    Directory of Open Access Journals (Sweden)

    Ievgeniia Zapunna

    2015-05-01

    Full Text Available The present article exhibits the results of systematic analysis on structure and planning of fragments of urban environment. The results have been obtained by looking into the prerequisites of formation of urban environment, specifically the impact of the Magdeburg Rights on urban culture. The study covers the small towns in Ukraine, which retained their historical background to a greater extent. 70 towns in Ukraine that had the Magdeburg Law have been analyzed and their historic, architectural and planning capacity investigated. The most valuable urban fragments have been classified in accordance with a number of criteria, such as the form of the plan, planning composition, etc. Based on the conducted analysis the author presents further generalized proposals for comprehensive development of historical and architectural heritage within the socio-cultural and tourism infrastructure of the Ukrainian towns.

  8. Galactic structure and dynamics with late-type stars

    Science.gov (United States)

    Polak, Allyson Anne

    Stellar populations provide important clues to the evolution of the Milky Way. We report the results of two surveys of late-type stars aimed at understanding the nature (dynamics, chemistries) of the disk and halo Galactic stellar populations. We study the kinematical properties of 303 late-type dwarfs out to ~6 kpc at the North Galactic Pole (NGP) as derived from deep ( V ~22), high precision (.001" yr -1 ) proper motions by Majewski (1992) combined with new deep CCD photometry, which yield photometry parallaxes needed to convert the proper motions to U and V space motions. A clear disk population to Z ~3 kpc can be discerned with a strong asymmetric drift gradient of -46±4 km s -1 kpc -1. Halo dwarfs dominate over the thick disk at Z ~3 kpc. In addition to the strong signal of disk stars, a retrograde halo moving group is identified in the U - V plane that is likely the same as the moving group detected at the NGP by Majewski (1992). We have also obtained medium resolution (2-4 Å) spectra for 749 late K and early M giants at mid-latitudes selected from the 2MASS catalog with the FOBOS system at Fan Mountain Observatory. These spectra provide radial velocities (RVs) at the 5 km s -1 level, spectroscopic [Fe/H] good to [sigma]=0.25 dex, and information on the relative abundances of Mg/Fe and Na/Fe in these stars. The UCAC2 proper motions and RVs yield full stellar space motions. We find ail asymmetric drift for the thin/thick disk of -26±4 kill s -1 kpc -1 , significantly smaller than that found for the M dwarf sample above. We attribute the difference to purity of sample in that M giants are not found in the halo field except in readily identifiable halo substructures. Based on the lack of a vertical gradient in the [[alpha]/Fe]-[Fe/H] patterns and the strong vertical gradient in rotational velocity for both of our surveys, we conclude that our findings support a most likely formation scenario in which the thick disk was formed by the heating of the early disk due to a merger.

  9. Effect of heat treatment conditions on the structure and mechanical properties of DP-type steel

    OpenAIRE

    J. Adamczyk; A. Grajcar

    2006-01-01

    Purpose: The aim of the paper is to determine the influence of the initial structure and heat treatment conditions on mechanical properties of DP-type steel.Design/methodology/approach: The heat treatment of the low-carbon steel in order to obtain a DP-type structure of desirable ferrite and martensite fractions was realized. In order to investigate the structure light and transmission electron microscopy methods were used. Mechanical properties were determined by means of tensile test.Find...

  10. Characterisation of proton incorporation in perovskite-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Sala, B.; Willemin, S.; Lacroix, O.; Py, J.P. [AREVA NP, Technical Centre - detached at IEM CC047 Place Eugene Bataillon 34095 Montpellier, (France); Colomban, Ph. [Laboratoire de Dynamique, Interactions et Reactivite, UMR 7075 CNRS-UPMC, 2 rue H. Dunant 94 320 Thiais, (France); Julbe, A. [Institut Europeen des membranes CC047 Place Eugene Bataillon France-34095 Montpellier, (France); Rahmouni, K.; Takenouti, H. [Laboratoire des interfaces et des systemes electrochimiques Case 133, Universite Pierre et Marie Curie, 4 place Jussieu, Paris Cedex 05 (France)

    2006-07-01

    Hydrogen could play an increasingly important role as a future energetic carrier. Produced from water it may become a cost competitive alternative to hydrogen made from hydrocarbons. High temperature electrolysis (HTE) could make important contributions where low cost power is available, particularly if coupled with a nuclear plant providing electricity and heat free of greenhouse gas. HTE using H{sup +} ionic electrolyte may operate around 500 C, thus representing technical and economical interest. According to the literature, satisfactory conductivities could be reached with proton conductor ceramic such as perovskites between 400 to 600 C. The ceramics are generally ABO{sub 3} type and doped by lanthanides. The oxides take protons from water vapor or hydrogen molecules in ambient gas as a result of equilibria with defects in the oxide lattice doped by aliovalent cations. This work is devoted to the study of: 1) Oxygen ion vacancies formation by dopant introduction thank to Raman spectroscopy 2) Proton incorporation by thermogravimetric analysis and Raman spectroscopy 3) Proton mobility by means of preliminary conductivity measurements. (authors)

  11. Characterisation of proton incorporation in perovskite-type structure

    International Nuclear Information System (INIS)

    Hydrogen could play an increasingly important role as a future energetic carrier. Produced from water it may become a cost competitive alternative to hydrogen made from hydrocarbons. High temperature electrolysis (HTE) could make important contributions where low cost power is available, particularly if coupled with a nuclear plant providing electricity and heat free of greenhouse gas. HTE using H+ ionic electrolyte may operate around 500 C, thus representing technical and economical interest. According to the literature, satisfactory conductivities could be reached with proton conductor ceramic such as perovskites between 400 to 600 C. The ceramics are generally ABO3 type and doped by lanthanides. The oxides take protons from water vapor or hydrogen molecules in ambient gas as a result of equilibria with defects in the oxide lattice doped by aliovalent cations. This work is devoted to the study of: 1) Oxygen ion vacancies formation by dopant introduction thank to Raman spectroscopy 2) Proton incorporation by thermogravimetric analysis and Raman spectroscopy 3) Proton mobility by means of preliminary conductivity measurements. (authors)

  12. Experimental investigation on sandwich structure ring-type ultrasonic motor.

    Science.gov (United States)

    Peng, Taijiang; Shi, Hongyan; Liang, Xiong; Luo, Feng; Wu, Xiaoyu

    2015-02-01

    This paper presents a manufacture method for a sandwich structure Ultrasonic Motor (USM) and experiment. Two pieces of rotor clamped on a stator, and a stainless steel disk-spring is bonded on the hollow rotor disk to provide the press by a nut assembled on the shaft. The stator is made of a double-side Printed-Circuit Board (PCB) which is sawed out the ring in the center and connected on the board with three legs. On each side of the ring surface, there are electrodes connected at the same position via through hole. The three layer drive circuit for sine, cosine, and ground signal is connected on the board through each leg. There are many piezoelectric components (PZT) bonded between two electrodes and fill soldering tin on each electrode. Then PZT is welded on PCB by reflow soldering. Finally, rub the gibbous soldering tin down to the position of PZT surface makes sure the surface contacts with rotor evenly. The welding process can also be completed by Surface Mounted Technology (SMT). A prototype motor is manufactured by this method. Two B03 model shapes of the stator are obtained by the finite element analysis and the optimal frequency of the motor is 56.375 kHz measured by impedance instrument. The theoretical analysis is conducted for the relationship between the revolving speed of the USM and thickness of stator ring, number of the travelling waves, PZT amplitude, frequency and the other parameters. The experiment result shows that the maximum revolving speed is 116 RPM and the maximum torque is 25 N mm, when the actuate voltage is 200 VAC. PMID:25213313

  13. Types of personality motivation structure of women who are acquiring higher education in psychology

    Directory of Open Access Journals (Sweden)

    TETIANA PARTYKO

    2013-09-01

    Full Text Available The article deals with the results of empirical research on the types of personality motivation structure of women who are acquiring higher education in psychology. Two types have been singled out: expressive and impulsive. The expressive type comprises two components: ideal motivation aimed at life necessities, general activity and social utility, and real motivation aimed at comfort, social status and communication. In the structure of the impulsive type there are three components: real motivation aimed at life necessities, social status, general activity and social utility; real motivation aimed at communication and comfort; creativity motivation aimed at self-development and creative activity. Women belonging to the expressive type of personality motivation structure have more positive self-attitude and a higher level of psychological well-being than women belonging to the impulsive type.

  14. Vertical and Horizontal Vegetation Structure across Natural and Modified Habitat Types at Mount Kilimanjaro

    Science.gov (United States)

    Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus

    2015-01-01

    In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866–4550m above sea level at Mount Kilimanjaro, Tanzania. Additionally, we compared (human)-modified habitats, including maize fields, traditionally managed home gardens, grasslands, commercial coffee farms and logged and burned forests with natural habitats along this elevation gradient. We distinguished vertical and horizontal vegetation structure to account for habitat complexity and heterogeneity. Vertical vegetation structure (assessed as number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) displayed a unimodal elevation pattern, peaking at intermediate elevations in montane forests, whereas horizontal structure (assessed as coefficient of variation of number, width and density of vegetation layers, maximum canopy height, leaf area index and vegetation cover) was lowest at intermediate altitudes. Overall, vertical structure was consistently lower in modified than in natural habitat types, whereas horizontal structure was inconsistently different in modified than in natural habitat types, depending on the specific structural measure and habitat type. Our study shows how vertical and horizontal vegetation structure can be assessed efficiently in various habitat types in tropical mountain regions, and we suggest to apply this as a tool for informing future biodiversity and ecosystem service studies. PMID:26406985

  15. The structure of the follistatin:activin complex reveals antagonism of both type I and type II receptor binding

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, T.B.; Lerch, T.F.; Cook, R.W.; Woodruff, T.K.; Jardetzky, T.S. (NWU)

    2010-03-08

    TGF-{beta} ligands stimulate diverse cellular differentiation and growth responses by signaling through type I and II receptors. Ligand antagonists, such as follistatin, block signaling and are essential regulators of physiological responses. Here we report the structure of activin A, a TGF-{beta} ligand, bound to the high-affinity antagonist follistatin. Two follistatin molecules encircle activin, neutralizing the ligand by burying one-third of its residues and its receptor binding sites. Previous studies have suggested that type I receptor binding would not be blocked by follistatin, but the crystal structure reveals that the follistatin N-terminal domain has an unexpected fold that mimics a universal type I receptor motif and occupies this receptor binding site. The formation of follistatin:BMP:type I receptor complexes can be explained by the stoichiometric and geometric arrangement of the activin:follistatin complex. The mode of ligand binding by follistatin has important implications for its ability to neutralize homo- and heterodimeric ligands of this growth factor family.

  16. Photovoltaic properties of ZnO nanorods/p-type Si heterojunction structures

    Directory of Open Access Journals (Sweden)

    Rafal Pietruszka

    2014-02-01

    Full Text Available Selected properties of photovoltaic (PV structures based on n-type zinc oxide nanorods grown by a low temperature hydrothermal method on p-type silicon substrates (100 are investigated. PV structures were covered with thin films of Al doped ZnO grown by atomic layer deposition acting as transparent electrodes. The investigated PV structures differ in terms of the shapes and densities of their nanorods. The best response is observed for the structure containing closely-spaced nanorods, which show light conversion efficiency of 3.6%.

  17. Influence of substrate type on structure of C-Pd thin films

    Science.gov (United States)

    Kowalska, Ewa; Czerwosz, El?bieta; Koz?owski, Miroslaw; Firek, Piotr

    2015-09-01

    C-Pd films were obtained by a two steps' PVD/CVD method (Physical Vapor Deposition/Chemical Vapor Deposition). Investigations of Pd nanograins structure and carbon matrix structure were performed. Many types of substrates (Si, Si covered with DLC layer, Al2O3 plate and AAO membrane) with various developing specific surface area (SSA) were applied and the influence on this surface on obtained films C-Pd was studied. We present the results of Scanning Electron Microscopy (SEM) studies with SE (Secondary Electrons) and LABE (Low Angle Backscattered Electrons) modes. Depending on the substrate type it was possible to obtain many different films and structures with various structural features.

  18. Growth of equilibrium structures built from a large number of distinct component types

    OpenAIRE

    Hedges, Lester O.; Mannige, Ranjan V.; Whitelam, Stephen

    2014-01-01

    We use simple analytic arguments and lattice-based computer simulations to study the growth of structures made from a large number of distinct component types. Components possess 'designed' interactions, chosen to stabilize an equilibrium target structure in which each component type has a defined spatial position, and 'undesigned' interactions that allow components to bind in a compositionally-disordered way. We find that high-fidelity growth of the equilibrium target struc...

  19. Structural and Mechanical Properties of Klebsiella pneumoniae Type 3 Fimbriae▿ §

    OpenAIRE

    Chen, Feng-Jung; Chan, Chia-Han; Huang, Ying-Jung; Liu, Kuo-Liang; Peng, Hwei-Ling; Chang, Hwan-You; Liou, Gunn-Guang; Yew, Tri-Rung; Liu, Cheng-Hsien; Hsu, Ken Y.; Hsu, Long

    2011-01-01

    This study investigated the structural and mechanical properties of Klebsiella pneumoniae type 3 fimbriae, which constitute a known virulence factor for the bacterium. Transmission electron microscopy and optical tweezers were used to understand the ability of the bacterium to survive flushes. An individual K. pneumoniae type 3 fimbria exhibited a helix-like structure with a pitch of 4.1 nm and a three-phase force-extension curve. The fimbria was first nonlinearly stretched with increasing fo...

  20. Effect of heat treatment conditions on the structure and mechanical properties of DP-type steel

    Directory of Open Access Journals (Sweden)

    J. Adamczyk

    2006-04-01

    Full Text Available Purpose: The aim of the paper is to determine the influence of the initial structure and heat treatment conditions on mechanical properties of DP-type steel.Design/methodology/approach: The heat treatment of the low-carbon steel in order to obtain a DP-type structure of desirable ferrite and martensite fractions was realized. In order to investigate the structure light and transmission electron microscopy methods were used. Mechanical properties were determined by means of tensile test.Findings: It was found that a different initial structure influences essentially the martensite morphology in a final DP-type structure. It can occur as a network, fine fibres or islands in a ferritic matrix of high dislocation density in the vicinity of diffusionless transformation products of austenite. The best mechanical properties (UTS=800MPa, YS0.2=520MPa, TEl=20%, UEl=16% has a steel with the martensite in a form of fine fibres.Research limitations/implications: Continuation of the investigations in the field of using the thermomechanical processing to obtain a DP-type steel is foreseen.Practical implications: The established heat treatment conditions can be useful at manufacturing DP-type sheets of high strength and ductile properties and a good suitability for metalforming operations.Originality/value: The relationship between the initial structure and martensite morphology in DP-type steels was specified.

  1. The structure of galaxies : the division of stellar mass by morphological type and structural component

    OpenAIRE

    Kelvin, Lee Steven

    2013-01-01

    The mechanisms which cause galaxies to form and evolve each leave behind distinct structural markers in their wake. Dynamically hot processes (e.g., monolithic collapse, hierarchical merging) give rise to pressure-supported spheroidal structures, including elliptical galaxies and classical bulges. By contrast, dynamically cold processes (e.g., gas accretion, AGN splashback) lead to flattened rotationally-supported disk-like structures, often found on their own or as part of a spiral galaxy. I...

  2. Imma perovskite-type oxynitride LaTiO2N: structure and electron density.

    Science.gov (United States)

    Yashima, Masatomo; Saito, Mio; Nakano, Hiromi; Takata, Tsuyoshi; Ogisu, Kiyonori; Domen, Kazunari

    2010-07-14

    We present the first example of Imma perovskite-type oxynitride. LaTiO(2)N was found to have an Imma perovskite-type structure with a(0)b(-)b(-) tilt system. The Ti-(O,N) covalent bonding and existence of N atoms are responsible for the reduced band gap of LaTiO(2)N photocatalyst. PMID:20485779

  3. Using a conceptual framework during learning attenuates the loss of expert-type knowledge structure

    Directory of Open Access Journals (Sweden)

    Wilcox Elizabeth

    2006-07-01

    Full Text Available Abstract Background During evolution from novice to expert, knowledge structure develops into an abridged network organized around pathophysiological concepts. The objectives of this study were to examine the change in knowledge structure in medical students in one year and to investigate the association between the use of a conceptual framework (diagnostic scheme and long-term knowledge structure. Methods Medical students' knowledge structure of metabolic alkalosis was studied after instruction and one year later using concept-sorting. Knowledge structure was labeled 'expert-type' if students shared ? 2 concepts with experts and 'novice-type' if they shared Results Thirty-four medical students completed the concept-sorting task on both occasions. Twenty-four used a diagnostic scheme for metabolic alkalosis. Short-term knowledge structure was not a correlate of long-term knowledge structure, whereas use of a diagnostic scheme was associated with increased odds of expert-type long-term knowledge structure (odds ratio 12.6 [1.4, 116.0], p = 0.02. There was an interaction between short-term knowledge structure and the use of a diagnostic scheme. In the group who did not use a diagnostic scheme the number of students changing from expert-type to novice-type was greater than vice versa (p = 0.046. There was no significant change in the group that used the diagnostic scheme (p = 0.6. Conclusion The use of a diagnostic scheme by students may attenuate the loss of expert-type knowledge structure.

  4. Type II Heat-labile Enterotoxins: Structure, Function, and Immunomofdulatory Properties

    OpenAIRE

    Hajishengallis, George; Connell, Terry D.

    2012-01-01

    The heat-labile enterotoxins (HLTs) of Escherichia coli and Vibrio cholerae are classified into two major types on the basis of genetic, biochemical, and immunological properties. Type I and Type II HLT have been intensively studied for their exceptionally strong adjuvant activities. Despite general structural similarities, these molecules, in intact or derivative (non-toxic) forms, display notable differences in their mode of immunomodulatory action. The molecular basis of these differences ...

  5. Structure, thermal and electrical properties of layered perovskite type Pr2Ti2O7

    International Nuclear Information System (INIS)

    A2B2O7 type compositions with A = trivalent rare-earth ions and B= tetravalent ions, like Ti4+, Zr4+, Hf4+ and Sn4+, have been of interest due to their interesting crystal chemistry and several technological applications. For Ti4+ as B site cation, the A2B2O7 type rare-earth (Ln) titanates form monoclinic perovskite type structure for Ln = La, Nd and Pr while all others form cubic pyrochlore type structure. The monoclinic perovskite type titanates have been of attraction due to their high Curie temperature ferroelectric and piezoelectric properties. Though such titanates have been of technological importance, their structure and phase transition are still remained obscure in literature. A number of symmetry and unit cell parameters have been proposed for such titanates. But all the structures are closely related and they only differed by the shift the rare-earth ions as well as distortion and tilt of the TiO6 octahedral units. Herein we have reported the structure and properties of monoclinic Pr2Ti2O7. Further total energy calculation using DFT formalism were carried out to compare the energetic of different structures. The structural and electrical properties of Pr2Ti2O7 have also been investigated

  6. Influence of solvent type on structure, mechanical and thermal properties of fullerene containing films of polyethylene

    International Nuclear Information System (INIS)

    This article is devoted to influence of solvent type on structure, mechanical and thermal properties of fullerene containing films of polyethylene. The structure, mechanical and thermal properties of fullerene containing films of polyethylene in various aromatic solvents of benzene and its derivatives are investigated.

  7. Response of Dome-enclosed Box-type Structure to Underwater Explosion

    Directory of Open Access Journals (Sweden)

    O. R. Nandagopan

    2013-07-01

    Full Text Available In the development of underwater sensor systems, the sensor arrays are configured for different shapes like cylindrical, rectangular and spherical depending on the requirement. The rectangular shaped box–type structure discussed here has both top and bottom ends open. Flanges stiffen the top and bottom ends, and gussets are used to connect the flanges with the structure. In this paper, the box-type structure is subjected to non-contact underwater explosion in a shock tank to study the peak free field pressure on the structure. To simulate the actual conditions, the structure is placed in free flooded area and covered with a dome. The free-field peak pressure on the dome and structure are plotted with time. The measured pressure curves are in agreement with the empirical predictions reported in literature. It is concluded that around 85 per cent of the shock impulse acting on the dome is transmitted to the box-type structure. The dome and box-type structure withstood the explosive load, thereby validating their design.Defence Science Journal, 2013, 63(4, pp.381-385, DOI:http://dx.doi.org/10.14429/dsj.63.2130

  8. Response of Dome-enclosed Box-type Structure to Underwater Explosion

    Directory of Open Access Journals (Sweden)

    O.R. Nandagopan

    2013-07-01

    Full Text Available In the development of underwater sensor systems, the sensor arrays are configured for different shapes like cylindrical, rectangular and spherical depending on the requirement. The rectangular shaped box–type structure discussed here has both top and bottom ends open. Flanges stiffen the top and bottom ends, and gussets are used to connect the flanges with the structure. In this paper, the box-type structure is subjected to non-contact underwater explosion in a shock tank to study the peak free field pressure on the structure. To simulate the actual conditions, the structure is placed in free flooded area and covered with a dome. The free-field peak pressure on the dome and structure are plotted with time. The measured pressure curves are in agreement with the empirical predictions reported in literature. It is concluded that around 85 per cent of the shock impulse acting on the dome is transmitted to the box-type structure. The dome and box-type structure withstood the explosive load, thereby validating their design.

  9. Dance Class Structure Affects Youth Physical Activity and Sedentary Behavior: A Study of Seven Dance Types

    Science.gov (United States)

    Lopez Castillo, Maria A.; Carlson, Jordan A.; Cain, Kelli L.; Bonilla, Edith A.; Chuang, Emmeline; Elder, John P.; Sallis, James F.

    2015-01-01

    Purpose: The study aims were to determine: (a) how class structure varies by dance type, (b) how moderate-to-vigorous physical activity (MVPA) and sedentary behavior vary by dance class segments, and (c) how class structure relates to total MVPA in dance classes. Method: Participants were 291 boys and girls ages 5 to 18 years old enrolled in 58…

  10. Sc29Fe6 a new structure type of the intermetallic compounds

    International Nuclear Information System (INIS)

    The crystal structure of Sc29Fe6 compound is investigated by the monocrystal method and belongs to a new type (space group Pm3, a=1.4361(2) nm). The structure is refined by 285 independent reflexes up to the divergence factor,R=0.067, with isotropic temperature parameters for all atoms, 140 atoms in the elementary cell of Sc29Fe6 structure are placed in 13 proper point systems. The coordination numbers of Sc atoms are 15, 12, and Fe - 12, 11. The icosahedral coordination of atoms is met more often. Sc29Fe6 structure is similar to Sc57Rh13 structure

  11. The Types of Argument Structure Used by Hillary Clinton in the CNN Democratic Presidential Debate

    OpenAIRE

    Anggie Angeline; Nani Indrajani T.

    2009-01-01

    This qualitative research was conducted to examine the types of argument structure by Hillary Clinton in part one of the CNN Democratic Presidential Debate since Hillary, who had a great deal of experiences in political parties, was supposed to be able to construct convincing arguments that had good argument structures. The theories used to analyze were Bierman and Assali’s (1996), King’s (n.d.) and Stanlick’s (2003). The findings showed that there were five types of argument structure used: ...

  12. Of the crystal chemistry of Ruddlesden-Porter type structures in high Tc ceramic superconductors

    International Nuclear Information System (INIS)

    This paper reports on atomistic computer simulation employed to examine the energetics and crystal chemistry of some Ruddlesden-Popper type oxide superconductors. Similar structural patterns have been noticed in the superconducting oxides. The formation of Ruddlesden-Popper type layers (alternating slabs of rocksalt and perovskite structures) is similar in many respects to that seen in the system Sr-Ti-O. However, there are some significant differences, for example, the rocksalt and perovskite blocks in the new superconducting compounds are not necessarily electrically neutral unlike in the Sr-Ti-O system and this may well lead to significant differences in their structural chemistry

  13. Structural and Thermal Safety Analysis Report for the Type B Radioactive Waste Transport Package

    Energy Technology Data Exchange (ETDEWEB)

    Kim, D. H.; Seo, K. S.; Lee, J. C.; Bang, K. S

    2007-09-15

    We carried out structural safety evaluation for the type B radioactive waste transport package. Requirements for type B packages according to the related regulations such as IAEA Safety Standard Series No. TS-R-1, Korea Most Act. 2001-23 and US 10 CFR Part 71 were evaluated. General requirements for packages such as those for a lifting attachment, a tie-down attachment and pressure condition were considered. For the type B radioactive waste transport package, the structural, thermal and containment analyses were carried out under the normal transport conditions. Also the safety analysis were conducted under the accidental transport conditions. The 9 m drop test, 1 m puncture test, fire test and water immersion test under the accidental transport conditions were consecutively done. The type B radioactive waste transport packages were maintained the structural and thermal integrities.

  14. Crystal structure of a synthetic tin-selenium representative of the cylindrite structure type.

    Czech Academy of Sciences Publication Activity Database

    Makovicky, E.; Pet?í?ek, Václav; Dušek, Michal; Topa, D.

    2008-01-01

    Ro?. 93, 11-12 (2008), s. 1787-1798. ISSN 0003-004X R&D Projects: GA ?R GA202/06/0757 Institutional research plan: CEZ:AV0Z10100521 Keywords : cylindrite * tin- antimony -iron selenide * non-commensurate layer structure * layer-misfit structure * interlayer match Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.962, year: 2008

  15. Variations of Structural Components: Specific Intercultural Differences in Facial Morphology, Skin Type, and Structures

    OpenAIRE

    McKnight, Aisha; Momoh, Adeyiza O.; Bullocks, Jamal M.

    2009-01-01

    Analysis of the differences in facial morphology and skin structure and tone among ethnic groups within the realm of plastic surgery is relevant due to the increasing number of ethnic individuals seeking cosmetic surgery. Previous classifications of ideal facial morphologic characteristics have been revised and challenged over the years to accurately reflect the differences in facial structure that are aesthetically pleasing to individuals of differing ethnic groups. The traditional neoclassi...

  16. Dipole ordering, ionic conductivity, and cold nuclear fusion: Three types of cation mobility in the orthophosphates KTiOPO4 Na3M2(PO4)3 (M=Sc,Fe,Cr), NaTh2(PO4)3, KD2PO4, and related compounds

    International Nuclear Information System (INIS)

    As shown in earlier studies, crystals whose structures contain closely located positions statistically occupied by metal cations (split positions) may exhibit anomalies in physical properties, such as ferroelectric (FE) or antiferroelectric (AFE) ordering, superionic conduction (SIC), low thermal expansion coefficients, ultrarapid nuclear relaxation, etc. For example, splitting of Na positions lead to Fe ordering in low-temperature structures of Na3Sc2(PO4)3 and NaTh2(PO4)3 and to AFE ordering in Na3Zr2Si2PO12 (stoichiometric NASICON - one of the best three-dimensional superionic conductors). The coexistance of two types of split cation positions in KFeFPO4 was reported by Belokoeneva et al.; later, these splittings were shown to be accompanied by FE and AFE ordering. In this paper, the authors report an attempt to establish inter-relations between various physical phenomena related to cation mobility. They discuss three manifestations of cation mobility in orthophosphates with split cation positions: dipole ordering of both FE and AFE types, superionic conduction, and cold nuclear fusion (CNF)

  17. Distinctive structure in dynamic spectra of type V solar radio bursts

    Energy Technology Data Exchange (ETDEWEB)

    Bakunin, L.M.; Markeev, A.K.; Fomichev, V.V.; Chertok, I.M.

    1979-05-01

    Observations of type V solar radio bursts obtained with a 45--90 MHz radio spectrograph at the Institute of Terrestrial Magnetism are discussed. The dynamic spectra of type V events are highly diversified and complex. Categories of bursts are discriminated, depending on the behavior of the radiation at the leading and trailing edges. Various types of fine structure are encountered in the dynamic spectra of many bursts. An analysis is made of type V bursts that distinctly exhibit radio emission at the frequencies of the fundamental and the second harmonic.

  18. The Types of Argument Structure Used by Hillary Clinton in the CNN Democratic Presidential Debate

    Directory of Open Access Journals (Sweden)

    Anggie Angeline

    2009-01-01

    Full Text Available This qualitative research was conducted to examine the types of argument structure by Hillary Clinton in part one of the CNN Democratic Presidential Debate since Hillary, who had a great deal of experiences in political parties, was supposed to be able to construct convincing arguments that had good argument structures. The theories used to analyze were Bierman and Assali’s (1996, King’s (n.d. and Stanlick’s (2003. The findings showed that there were five types of argument structure used: serial, linked, convergent, divergent, and hybrid argument structures. The linked argument structure was the argument structure used the most frequently in Hillary’s utterances in the debate, while the divergent was the least one. Thus, it could be concluded that Hillary’s speech in the Presidential Debate was quite interesting since she could combine all the five types of argument structure, though the frequency of using them was not the same and it seems that linked argument structure was the most effective strategy for her in arguing about the politic, economy, and social issues.

  19. In Situ D-periodic Molecular Structure of Type II Collagen

    Energy Technology Data Exchange (ETDEWEB)

    Antipova, Olga; Orgel, Joseph P.R.O. (IIT)

    2010-05-06

    Collagens are essential components of extracellular matrices in multicellular animals. Fibrillar type II collagen is the most prominent component of articular cartilage and other cartilage-like tissues such as notochord. Its in situ macromolecular and packing structures have not been fully characterized, but an understanding of these attributes may help reveal mechanisms of tissue assembly and degradation (as in osteo- and rheumatoid arthritis). In some tissues such as lamprey notochord, the collagen fibrillar organization is naturally crystalline and may be studied by x-ray diffraction. We used diffraction data from native and derivative notochord tissue samples to solve the axial, D-periodic structure of type II collagen via multiple isomorphous replacement. The electron density maps and heavy atom data revealed the conformation of the nonhelical telopeptides and the overall D-periodic structure of collagen type II in native tissues, data that were further supported by structure prediction and transmission electron microscopy. These results help to explain the observed differences in collagen type I and type II fibrillar architecture and indicate the collagen type II cross-link organization, which is crucial for fibrillogenesis. Transmission electron microscopy data show the close relationship between lamprey and mammalian collagen fibrils, even though the respective larger scale tissue architecture differs.

  20. Optimum Design for Slot-type of Stator Based on PM Motor with Halbach Structure

    Directory of Open Access Journals (Sweden)

    Zhu Yongxin

    2015-01-01

    Full Text Available The performance of permanent magnet motor is directly influenced by the PM structure of rotor and the slot type of stator. An emerging rotor magnetization type of PM motor is Halbach structure, which has obvious advantages in comparison to ordinary permanent structures and in application, especially in the design of propeller integration system. Commonly, Halbach array is used in discrete permanent magnet structure on the rotor of machine. On the stator, air gap flux density varies as the slot type changes, and complex slot types will bring about complex air gap equivalent process of the motor, which will influence the procedures of simulation calculation and experiments. According to the characteristics of Halbach array, the intensifying effect of the Halbach array on magnetic flux density of air gap is analyzed in this paper, and the electromagnetic field of PM motor is calculated. By using FEM method, the magnetic flux density of air gap, back phase electromotive force and electromagnetic torque are compared under different slot types. Simulation result shows the peer slot is best. Experiments on a 60kW PM Motor with Halbach Structure and peer slot is in good agreement with simulation.

  1. Cryo-EM structures of two bovine adenovirus type 3 intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Lingpeng; Huang, Xiaoxing; Li, Xiaomin [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Xiong, Wei [State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Luo-jia-shan, Wuhan, Hubei 430072 (China); Sun, Wei; Yang, Chongwen; Zhang, Kai; Wang, Ying [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Liu, Hongrong [College of Physics and Information Science, Hunan Normal University, Changsha, Hunan 410081 (China); Huang, Xiaojun; Ji, Gang; Sun, Fei [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Zheng, Congyi, E-mail: cctcc202@whu.edu.cn [State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Luo-jia-shan, Wuhan, Hubei 430072 (China); Zhu, Ping, E-mail: zhup@ibp.ac.cn [National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China)

    2014-02-15

    Adenoviruses (Ads) infect hosts from all vertebrate species and have been investigated as vaccine vectors. We report here near-atomic structures of two bovine Ad type 3 (BAd3) intermediates obtained by cryo-electron microscopy. A comparison between the two intermediate structures reveals that the differences are localized in the fivefold vertex region, while their facet structures are identical. The overall facet structure of BAd3 exhibits a similar structure to human Ads; however, BAd3 protein IX has a unique conformation. Mass spectrometry and cryo-electron tomography analyses indicate that one intermediate structure represents the stage during DNA encapsidation, whilst the other intermediate structure represents a later stage. These results also suggest that cleavage of precursor protein VI occurs during, rather than after, the DNA encapsidation process. Overall, our results provide insights into the mechanism of Ad assembly, and allow the first structural comparison between human and nonhuman Ads at backbone level. - Highlights: • First structure of bovine adenovirus type 3. • Some channels are located at the vertex of intermediate during DNA encapsidation. • Protein IX exhibits a unique conformation of trimeric coiled–coiled structure. • Cleavage of precursor protein VI occurs during the DNA encapsidation process.

  2. Outer-Sphere Contributions to the Electronic Structure of Type Zero Copper Proteins

    Science.gov (United States)

    Lancaster, Kyle M.; Zaballa, María-Eugenia; Sproules, Stephen; Sundararajan, Mahesh; DeBeer, Serena; Richards, John H.; Vila, Alejandro J.; Neese, Frank; Gray, Harry B.

    2016-01-01

    Bioinorganic canon states that active-site thiolate coordination promotes rapid electron transfer (ET) to and from type 1 copper proteins. In recent work, we have found that copper ET sites in proteins also can be constructed without thiolate ligation (called “type zero” sites). Here we report multifrequency electron paramagnetic resonance (EPR), magnetic circular dichroism (MCD), and nuclear magnetic resonance (NMR) spectroscopic data together with density functional theory (DFT) and spectroscopy-oriented configuration interaction (SORCI) calculations for type zero Pseudomonas aeruginosa azurin variants. Wild-type (type 1) and type zero copper centers experience virtually identical ligand fields. Moreover, O-donor covalency is enhanced in type zero centers relative that in the C112D (type 2) protein. At the same time, N-donor covalency is reduced in a similar fashion to type 1 centers. QM/MM and SORCI calculations show that the electronic structures of type zero and type 2 are intimately linked to the orientation and coordination mode of the carboxylate ligand, which in turn is influenced by outer-sphere hydrogen bonding. PMID:22563915

  3. 1H and 15N NMR resonance assignments and secondary structure of titin type I domains

    International Nuclear Information System (INIS)

    Titin/connect in is a giant muscle protein with a highly modular architecture consisting of multiple repeats of two sequence motifs, named type I and type II. Type I modules have been suggested to be intracellular members of the fibronectin type III (Fn3) domain family. Along the titin sequence they are exclusively present in the region of the molecule located in the sarcomere A-band. This region has been shown to interact with myosin and C-protein. One of the most noticeable features of type I modules is that they are particularly rich in semiconserved prolines, since these residues account for about 8% of their sequence. We have determined the secondary structure of a representative type I domain (A71) by 15N and 1HNMR. We show that the type I domains of titin have the Fn3 fold as proposed, consisting of a three- and a four-stranded ?-sheet. When the two sheets are placed on top of each other to form the ?-sandwich characteristic of the Fn3 fold, 8 out of 10 prolines are found on the same side of the molecule and form an exposed hydrophobic patch. This suggests that the semiconserved prolines might be relevant for the function of type I modules, providing a surface for binding to other A-band proteins. The secondary structure of A71 was structurally aligned to other extracellular Fn3 modules of known 3D structure. The alignment shows that titin type I modules have closest similarity to the first Fn3 domain of Drosophila neuroglian

  4. X-ray structure of a soluble Rieske-type ferredoxin from Mus musculus

    International Nuclear Information System (INIS)

    The X-ray crystal structure of a soluble Rieske ferredoxin from M. musculus was solved at 2.07 Å resolution, revealing an iron–sulfur cluster-binding domain with similar architecture to the Rieske-type domains of bacterial aromatic dioxygenases. The ferredoxin was also shown to be capable of accepting electrons from both eukaryotic and prokaryotic oxidoreductases. The 2.07 Å resolution X-ray crystal structure of a soluble Rieske-type ferredoxin from Mus musculus encoded by the gene Mm.266515 is reported. Although they are present as covalent domains in eukaryotic membrane oxidase complexes, soluble Rieske-type ferredoxins have not previously been observed in eukaryotes. The overall structure of the mouse Rieske-type ferredoxin is typical of this class of iron–sulfur proteins and consists of a larger partial ?-barrel domain and a smaller domain containing Cys57, His59, Cys80 and His83 that binds the [2Fe–2S] cluster. The S atoms of the cluster are hydrogen-bonded by six backbone amide N atoms in a pattern typical of membrane-bound high-potential eukaryotic respiratory Rieske ferredoxins. However, phylogenetic analysis suggested that the mouse Rieske-type ferredoxin was more closely related to bacterial Rieske-type ferredoxins. Correspondingly, the structure revealed an extended loop most similar to that seen in Rieske-type ferredoxin subunits of bacterial aromatic dioxygenases, including the positioning of an aromatic side chain (Tyr85) between this loop and the [2Fe–2S] cluster. The mouse Rieske-type ferredoxin was shown to be capable of accepting electrons from both eukaryotic and prokaryotic oxidoreductases, although it was unable to serve as an electron donor for a bacterial monooxygenase complex. The human homolog of mouse Rieske-type ferredoxin was also cloned and purified. It behaved identically to mouse Rieske-type ferredoxin in all biochemical characterizations but did not crystallize. Based on its high sequence identity, the structure of the human homolog is likely to be modeled well by the mouse Rieske-type ferredoxin structure

  5. Recent advances in understanding structure-function relationships in the type II topoisomerase mechanism.

    Science.gov (United States)

    Schoeffler, A J; Berger, J M

    2005-12-01

    DNA topos (topoisomerases) are complex, multisubunit enzymes that remodel DNA topology. Members of the type II topo family function by passing one segment of duplex DNA through a transient break in another, a process that consumes two molecules of ATP and requires the co-ordinated action of multiple domains. Recent structural data on type II topo ATPase regions, which activate and enforce the directionality of DNA strand passage, have highlighted how ATP physically controls the catalytic cycle of the enzyme. Structural and biochemical studies of specialized DNA-binding domains in two paralogous bacterial type IIA topos (DNA gyrase and topo IV) show how these enzymes selectively negatively supercoil or decatenate DNA. Taken together, these findings expand our understanding of how disparate functional elements work together to co-ordinate the type II topo mechanism. PMID:16246147

  6. Allelic diversity and population structure of Bacillus sphaericus as revealed by multilocus sequence typing.

    Science.gov (United States)

    Ge, Yong; Hu, Xiaomin; Zheng, Dasheng; Wu, Yiming; Yuan, Zhiming

    2011-08-01

    The genetic diversity of 35 Bacillus sphaericus strains was analyzed by a newly developed multilocus sequence typing (MLST) scheme, toxin gene pool survey, and mosquito bioassay. The results demonstrated that strains assigned to the same sequence type (ST) had the same occurrence of toxin genes. Further sequence analysis revealed that toxic strains presented a nearly clonal population structure, whereas nontoxic strains had a high level of heterogeneity and were significantly distinct from toxic strains. PMID:21685170

  7. Allelic Diversity and Population Structure of Bacillus sphaericus as Revealed by Multilocus Sequence Typing ? †

    OpenAIRE

    Ge, Yong; Hu, Xiaomin; Zheng, Dasheng; Wu, Yiming; Yuan, Zhiming

    2011-01-01

    The genetic diversity of 35 Bacillus sphaericus strains was analyzed by a newly developed multilocus sequence typing (MLST) scheme, toxin gene pool survey, and mosquito bioassay. The results demonstrated that strains assigned to the same sequence type (ST) had the same occurrence of toxin genes. Further sequence analysis revealed that toxic strains presented a nearly clonal population structure, whereas nontoxic strains had a high level of heterogeneity and were significantly distinct from to...

  8. BaAl4-type derivative structure in superconducting La-Pd-Ge system

    International Nuclear Information System (INIS)

    There are many ternary intermetallic compounds with BaAl4-type and its derivative structures. LaPd2Ge2 is already known as one of the BaAl4-type superconductors with Tc of 1.12 K. We have synthesized a new intermetallic compound La3Pd4Ge4 with higher Tc of 2.75 K than that of LaPd2Ge2, which had the structure with the insertion of the AlB2-type layer in LaPd2Ge2. A detailed crystal structure analysis of La3Pd4Ge4 was carried out by neutron powder diffraction because it is useful to the analysis of small interplanar spacing. The neutron diffraction study indicates that La3Pd4Ge4 has U3Ni4Si4-type structure with a lower symmetry than that of LaPd2Ge2, and the typical interatomic distances of La3Pd4Ge4 are shorter than those of LaPd2Ge2. The coordination of Pd to three Ge in the AlB2-type layer of La3Pd4Ge4 is characteristic, which is not stabilized in other lanthanide-substituted intermetallics Ln3Pd4Ge4 (Ln = Y, Gd-Yb)

  9. Prediction, conservation analysis, and structural characterization of mammalian mucin-type O-glycosylation sites

    DEFF Research Database (Denmark)

    Julenius, Karin; Mølgaard, Anne; Gupta, Ramneek; Brunak, Søren

    2004-01-01

    than a nonglycosylated one. The Protein Data Bank was analyzed for structural information, and 12 glycosylated structures were obtained. All positive sites were found in coil or turn regions. A method for predicting the location for mucin-type glycosylation sites was trained using a neural network...... could be predicted from averaged properties together with the fact that glycosylation sites are not precisely conserved indicates that mucin-type glycosylation in most cases is a bulk property and not a very site-specific one. NetOGlyc 3.1 is made available at www.cbs.dtu.dk/services/netoglyc....

  10. Novel Compact Mushroom-Type EBG Structure for Electromagnetic Coupling Reduction of Microstrip Antenna array

    Science.gov (United States)

    Hu, Lizhong; Wang, Guangming; Liang, Jiangang; Zhang, Chenxin

    2015-03-01

    A novel compact electromagnetic bandgap (EBG) structure consisting of two turns complementary spiral resonator (CSR) and conventional mushroom EBG (CM-EBG) structure is introduced to suppress the mutual coupling in antenna arrays for multiple-input and multiple-output (MIMO) applications. Eigenmode calculation is used to investigate the proposed CSR-loaded mushroom-type EBG (MT-EBG), which proved to exhibit bandgap property and a miniaturization of 48.9% is realized compared with the CM-EBG. By inserting the proposed EBG structure between two E-plane coupled microstrip antennas, a mutual coupling reduction of 8.13 dB has been achieved numerically and experimentally. Moreover, the EBG-loaded antenna has better far-field radiation patterns compared with the reference antenna. Thus, this novel EBG structure with advantages of compactness and high decoupling efficiency opens an avenue to new types of antennas with super performances.

  11. Structural Design Studies for a Large Pool Type SFR of 1200 MWe

    International Nuclear Information System (INIS)

    The conceptual design studies of a sodium-cooled fast reactor (SFR) have been performed. The reactor is a pool type and 2-loop system with an 1200 MWe electrical capacity. The core outlet temperature is 545 deg. C, and the inlet one is 390 deg. C. Most internal structures and components are exposed to a high temperature environment. The mechanical governing loads of the reactor are the thermal and seismic loads because of the low operating pressure at an atmospheric level. The structural design targets are to maintain enough structural integrity for the high temperature thermal loads and for a seismic load of SSE 0.3g. Also an important target is to attain its economical competitiveness compared to other reactor types. Several structural design concepts are suggested to obtain the economical improvement of the NSSS (Nuclear Steam Supply System). (author)

  12. The Extracellular Architecture of Adherens Junctions Revealed by Crystal Structures of Type I Cadherins

    Energy Technology Data Exchange (ETDEWEB)

    O Harrison; X Jin; S Hong; F Bahna; G Ahlsen; J Brasch; Y Wu; J Vendome; K Felsovalyi; et al.

    2011-12-31

    Adherens junctions, which play a central role in intercellular adhesion, comprise clusters of type I classical cadherins that bind via extracellular domains extended from opposing cell surfaces. We show that a molecular layer seen in crystal structures of E- and N-cadherin ectodomains reported here and in a previous C-cadherin structure corresponds to the extracellular architecture of adherens junctions. In all three ectodomain crystals, cadherins dimerize through a trans adhesive interface and are connected by a second, cis, interface. Assemblies formed by E-cadherin ectodomains coated on liposomes also appear to adopt this structure. Fluorescent imaging of junctions formed from wild-type and mutant E-cadherins in cultured cells confirm conclusions derived from structural evidence. Mutations that interfere with the trans interface ablate adhesion, whereas cis interface mutations disrupt stable junction formation. Our observations are consistent with a model for junction assembly involving strong trans and weak cis interactions localized in the ectodomain.

  13. Universal Properties of Type IIB and F-theory Flux Compactifications at Large Complex Structure

    CERN Document Server

    Marsh, M C David

    2015-01-01

    We consider flux compactifications of type IIB string theory and F-theory in which the respective superpotentials at large complex structure are dominated by cubic or quartic terms in the complex structure moduli. In this limit, the low-energy effective theory for the complex structure and axio-dilaton sector exhibits universal properties that are insensitive to the details of the compactification manifold or the flux configuration. We show that there are no vacua in this region and the spectrum of the Hessian matrix is highly peaked and consists only of three distinct eigenvalues ($0$, $2m_{3/2}^2$ and $8m_{3/2}^2$), independently of the number of moduli. We briefly comment on how the inclusion of K\\"ahler moduli affect these findings. Our results generalise those of Brodie & Marsh [1], in which these universal properties were found in a subspace of the large complex structure limit of type IIB compactifications.

  14. Prediction of clathrate structure type and guest position by molecular mechanics.

    Science.gov (United States)

    Fleischer, Everly B; Janda, Kenneth C

    2013-05-16

    The clathrate hydrates occur in various types in which the number, size, and shape of the various cages differ. Usually the clathrate type of a specific guest is predicted by the size and shape of the molecular guest. We have developed a methodology to determine the clathrate type employing molecular mechanics with the MMFF force field employing a strategy to calculate the energy of formation of the clathrate from the sum of the guest/cage energies. The clathrate type with the most negative (most stable) energy of formation would be the type predicted (we mainly focused on type I, type II, or bromine type). This strategy allows for a calculation to predict the clathrate type for any cage guest in a few minutes on a laptop computer. It proved successful in predicting the clathrate structure for 46 out of 47 guest molecules. The molecular mechanics calculations also provide a prediction of the guest position within the cage and clathrate structure. These predictions are generally consistent with the X-ray and neutron diffraction studies. By supplementing the diffraction study with molecular mechanics, we gain a more detailed insight regarding the details of the structure. We have also compared MM calculations to studies of the multiple occupancy of the cages. Finally, we present a density functional calculation that demonstrates that the inside of the clathrates cages have a relatively uniform and low electrostatic potential in comparison with the outside oxygen and hydrogen atoms. This implies that van der Waals forces will usually be dominant in the guest-cage interactions. PMID:23600658

  15. Insect-inspired wing actuation structures based on ring-type resonators:

    OpenAIRE

    Bolsman, C.T.; Goosen, J.F.L.; Keulen, F.

    2008-01-01

    In this paper, we illustrate and study the opportunities of resonant ring type structures as wing actuation mechanisms for a flapping wing Micro Air Vehicle (MAV). Various design alternatives are presented and studied based on computational and physical models. Insects provide an excellent source of inspiration for the development of the wing actuation mechanisms for flapping wing MAVs. The insect thorax is a structure which in essence provides a mechanism to couple the wing muscles to the...

  16. Prodrome of Paranoid Schizophrenia with Episodic Type of Course and Schizoaffective Structure of Manifest Episode

    OpenAIRE

    Alexander S. Bobrov; Marina Yu. Rozhkova; Nina Yu. Rozhkova

    2014-01-01

    Prodrome of paranoid schizophrenia with the episodic type of course (F20.1 and F20.2 according to ICD-10) and the schizoaffective structure of the episode was retrospectively studied. The pronounced and persistent affect, in particular depression in conjunction with hallucinations and/or delusions throughout the whole episode, served as the basis for an episode qualification as the schizoaffective structure. Diagnosis of schizophrenia was confirmed by the extremely low socio-demographic indic...

  17. Frobenius type and CV-structures for Donaldson-Thomas theory and a convergence property

    CERN Document Server

    Barbieri, Anna

    2015-01-01

    We rephrase some well-known results in Donaldson-Thomas theory in terms of (formal families of) Frobenius type and CV-structures on a vector bundle in the sense of Hertling. We study these structures in an abstract setting, and prove a convergence result which is relevant to the case of triangulated categories. An application to physical field theory is also briefly discussed.

  18. Nomenclature of inorganic structure types; Report of the International Union of Crystallography Commission on Crystallographic Nomenclature Subcommittee on the Nomenclature of Inorganic Structure Types

    Energy Technology Data Exchange (ETDEWEB)

    Lima-de-Faria, J. (Instituto de Investigacao Cientifica Tropical, Lisbon (Portugal). Centro de Cristalografia e Mineralogia (Portugal)); Hellner, E. (Marburg Univ. (Germany, F.R.). Fachbereich 18 - Geowissenschaften (Germany, F.R.)); Liebau, F. (Kiel Univ. (Germany, F.R.). Mineralogisches Inst. (Germany, F.R.)); Makovicky, E. (Copenhagen Univ. (Denmark). Inst. for Mineralogy (Denmark)); Parthe, E. (Geneva Univ. (Switzerland). Lab. Crystallographie aux Rayons X (Switzerland))

    1990-01-01

    Different degrees of similarity between inorganic crystal structures are defined concisely and examples are presented that illustrate their practical application. A notation giving the coordination of atoms is presented together with some basic rules for developing crystal-chemical formulae and the Bauverband description of inorganic structure types. Typical examples of the nomenclature are: pyrite Fe{sup 6o}{l brace}g{r brace} S{sub 2} {sup (3;(1)t)}, F {radical} 2l + F'FeS{sub 2} Pa{anti 3}; spinel Mg{sup (4)}Al{sub 2} {sup 6}O{sub 4}, {sub {infinity}}{sup 3} Mg{sup (4t)}Al{sub 2} {sup 6o}O{sub 4}{sup (1,3; 12 co)}, F'' {sub 222} + C, T'MgAl{sub 2} O{sub 4} Fd {anti 3}m. (orig.).

  19. Comparative structural analysis of glycoprotein gD of herpes simplex virus types 1 and 2.

    OpenAIRE

    Eisenberg, R.J.; Ponce De Leon, M; Cohen, G.H.

    1980-01-01

    We studied the synthesis and processing of the type-common glycoprotein gD in herpes simplex virus type 2 (HSV-2) and compared it structurally to glycoprotein gD of herpes simplex virus type 1 (HSV-1). We demonstrated that in HSV-2, gD undergoes posttranslational processing from a lower-molecular-weight precursor (pgD51) to a higher-molecular-weight product (gD56). Tryptic peptide analysis by cation-exchange chromatography indicated that this processing step altered neither the methionine nor...

  20. Hamiltonian structure for a class of parametric coupled systems of the Korteweg-de Vries type

    International Nuclear Information System (INIS)

    We obtain from a lagrangian action describing a class of coupled parametric systems of KdV type its hamiltonian structure. The Poisson algebra arises from second class constraints of the theory and the use of Dirac brackets. The coupled system has relevant applications in physics

  1. Expressibility of the logic SOF on classes of structures of bounded FO types

    OpenAIRE

    Grosso, Alejandro; Turull Torres, José María

    2012-01-01

    We introduce a new property for classes of structures (or relational database instances), that we call bounded FO types. Then we prove that on such classes the expressive power of SOF collapses to rst order logic FO. As a consequence of this we prove that SOF is strictly included in SO.

  2. Crystal structure of a copper-transporting PIB-type ATPase

    DEFF Research Database (Denmark)

    Gourdon, Pontus Emanuel; Liu, Xiang-Yu; Skjørringe, Tina; Morth, J Preben; Møller, Lisbeth Birk; Pedersen, Bjørn Panyella; Nissen, Poul

    2011-01-01

    Heavy-metal homeostasis and detoxification is crucial for cell viability. P-type ATPases of the class IB (PIB) are essential in these processes, actively extruding heavy metals from the cytoplasm of cells. Here we present the structure of a PIB-ATPase, a Legionella pneumophila CopA Cu(+)-ATPase, in...

  3. Morphological and structural characteristics of powders of alumina by reaction combustion obtained through different types containers

    International Nuclear Information System (INIS)

    Among the existing types of synthesis, synthesis by combustion reaction is an effective method to produce nano-sized particles. The metallic nitrates that are sources of cations to form metal oxide, react with the fuel reducer quick, exothermic and self-sustaining. This paper aims to analyze the influence of container type on morphology and structural alumina powders obtained by combustion reaction. We evaluated two types of containers: vitreous silica crucible and crucible steel. The structural and morphological characteristics of the powders were analyzed by XRD, textural analysis by adsorption/desorption of N2 and SEM. The results showed the formation of single phase of alpha-Al2O4 for the two samples, showing a very significant difference between their respective surface areas. The morphology was comprised of pre-sintered particles without interparticle porosity forming thin plates of different sizes. (author)

  4. Proposal of a separated-type proton drift tube linac for a medium-energy structure

    International Nuclear Information System (INIS)

    A separated-type drift tube linac for medium energies from 150 to 300 MeV is proposed for a continuous-beam proton linac. The average effective shunt impedance increases by 55% compared with that of an alternating-periodic structure of the on-axis coupling type. Some technical difficulties in the manufacturing, alignment and cooling of the drift tube linac are greatly reduced by eliminating the focusing quadrupole magnets from the drift tubes. A modified design of a high-energy, high-average current 1-GeV proton linac with a continuous-beam is presented. It is pointed out that sudden transitions of focusing forces on both transverse and longitudinal motions, due to a change in the type of accelerating structure, are induced at two separated spots in the modified linac. On the contrary, they are induced simultaneously at the same spot in the originally proposed linac. (author)

  5. Relationship between the structural stability with the types and land uses in southeastern Spain

    International Nuclear Information System (INIS)

    Structural stability is one of the most important physical properties and is proposed as an indicator of quality. The aim of this study is to see the possible relationship between this property with soil types and uses of them. In this paper we have selected the Mazarron area based on their environmental characteristics and has taken forty-one topsoil samples, after analysis and study of the relationship between its structural stability with soil types and uses of same, we find a closer relationship in the case of uses that type, so that the natural soil as the percentage of stable aggregates close to 75%, while in soils anthropized this value reaches 44 %. (Author) 6 refs

  6. Structural limitations for optimizing garnet-type solid electrolytes: a perspective.

    Science.gov (United States)

    Zeier, Wolfgang G

    2014-11-21

    Lithium ion batteries exhibit the highest energy densities of all battery types and are therefore an important technology for energy storage in every day life. Today's commercially available batteries employ organic polymer lithium conducting electrolytes, leading to multiple challenges and safety issues such as poor chemical stability, leakage and flammability. The next generation lithium ion batteries, namely all solid-state batteries, can overcome these limitations through employing a ceramic Li(+) conducting electrolyte. In the past decade, there has been a major focus on the structural and ionic transport properties of lithium-conducting garnets, and the extensive research efforts have led to a thorough understanding of the structure-property relationships in this class of materials. However, further improvement seems difficult due to structural limitations. The purpose of this Perspective article is to provide a brief structural overview of Li conducting garnets and the structural influence on the optimization of Li-ionic conductivities. PMID:25277079

  7. Croatian banking sector research: relationship between ownership structure, concentration, owners’ type and bank performance

    Directory of Open Access Journals (Sweden)

    Igor Tomi?i?

    2012-12-01

    Full Text Available Banks are important financial intermediaries of any national economy, and corporate governance has an important role in banking sector; especially due to processes of the globalization and the internationalization, and also because of the sensitivity of the activities between the interest groups. The objective of this paper is to examine the relationship between ownership structure, concentration, owners’ type and bank performance. The authors made a research of banks' ownership structure using publicly available data. Using statistical tools authors discovered relationships between bank ownership structure and bank performance indicators (average asset, total asset, average equity, profit (loss before taxes, profit (loss after taxes, ROAA, ROAE. Further they discuss the relationships between ownership structure and a number of consequences for the bank performance. The authors discovered significant correlation between bank ownership structure and performance indicators variables that are described in the paper.

  8. Secondary cyclic hardening and dislocation structures in type 316 stainless steel at 6000C

    International Nuclear Information System (INIS)

    Polycrystalline type 316 stainless steel has been fatigued in air and in vacuum at 6000C at two constant plastic strain amplitudes. Although in air the curve of cyclic stress versus number of cycles is prematurely interrupted by failure, in vacuum it is sufficiently extended to allow secondary cyclic hardening to occur. Transmission electron microscopy observations show dislocation configurations (during the fatigue life) which are similar for both strain amplitudes. During the saturation plateau, several configurations coexist: regular walls, a labyrinth structure and persistent slip bands (PSBs) with a ladder structure. At failure (in vacuum) a cellular structure widely prevails while a labyrinth structure and PSBs with a ladder structure no longer exist. (orig./IHOE)

  9. Analysis of waves in the plasma guided by a periodical vane-type slow wave structure

    International Nuclear Information System (INIS)

    In this study, the dispersion relation has been derived to characterize the propagation of the waves in the plasma guided by a periodical vane-type slow wave structure. The plasma is confined by a quartz plate. Results indicate that there are two different waves in this structure. One is the plasma mode that originates from the plasma surface wave propagating along the interface between the plasma and the quartz plate, and the other is the guide mode that originally travels along the vane-type slow wave structure. In contrast to its original slow wave characteristics, the guide mode becomes a fast wave in the low-frequency portion of the passband, and there exists a cut-off frequency for the guide mode. The vane-type guiding structure has been shown to limit the upper frequency of the passband of the plasma mode, compared with that of the plasma surface wave. In addition, the passband of the plasma mode increases with the plasma density while it becomes narrower for the guide mode. The influences of the parameters of the guiding structure and plasma density on the propagation of waves are also presented

  10. The primary structure of a novel goose-type lysozyme from rhea egg white.

    Science.gov (United States)

    Pooart, Jureerut; Torikata, Takao; Araki, Tomohiro

    2004-01-01

    G-type lysozyme is a hydrolytic enzyme sharing a similar tertiary structure with plant chitinase. To discover the relation of function and structure, we analyzed the primary structure of new G-type lysozyme. The complete 185 amino acid residues of lysozyme from rhea egg white were sequenced using the peptides hydrolyzed by trypsin, V8 protease, and cyanogen bromide. Rhea lysozyme had sequence similarity to ostrich, cassowary, goose, and black swan, with 93%, 90%, 83%, and 82%, respectively. The six substituted positions were newly found at positions 3 (Asn), 9 (Ser), 43 (Arg), 114 (Ile), 127 (Met), and 129 (Arg) when compared with ostrich, cassowary, goose, and black swan lysozymes. The amino acid substitutions of rhea lysozyme at subsite B were the same as ostrich and cassowary lysozymes (Ser122 and Met123). This study was also constructed in a phylogenetic tree of G-type lysozyme that can be classified into at least three groups of this enzyme, namely, group 1; rhea, ostrich, and cassowary, group 2; goose, black swan, and chicken, and group 3; Japanese flounder. The amino acid sequences in assembled three alpha-helices found in this enzyme group (Thammasirirak, S., Torikata, T., Takami, K., Murata, K., and Araki, T., Biosci. Biotechnol. Biochem., 66, 147-156 (2002)) were also highly conserved, so that they were considered to be important for the formation of the hydrophobic core structure of the catalytic site and for maintaining a similar three-dimensional structure in this enzyme group. PMID:14745179

  11. Insights into the Mechanism of Type I Dehydroquinate Dehydratases from Structures of Reaction Intermediates

    Energy Technology Data Exchange (ETDEWEB)

    Light, Samuel H.; Minasov, George; Shuvalova, Ludmilla; Duban, Mark-Eugene; Caffrey, Michael; Anderson, Wayne F.; Lavie, Arnon (NWU); (UIC)

    2012-02-27

    The biosynthetic shikimate pathway consists of seven enzymes that catalyze sequential reactions to generate chorismate, a critical branch point in the synthesis of the aromatic amino acids. The third enzyme in the pathway, dehydroquinate dehydratase (DHQD), catalyzes the dehydration of 3-dehydroquinate to 3-dehydroshikimate. We present three crystal structures of the type I DHQD from the intestinal pathogens Clostridium difficile and Salmonella enterica. Structures of the enzyme with substrate and covalent pre- and post-dehydration reaction intermediates provide snapshots of successive steps along the type I DHQD-catalyzed reaction coordinate. These structures reveal that the position of the substrate within the active site does not appreciably change upon Schiff base formation. The intermediate state structures reveal a reaction state-dependent behavior of His-143 in which the residue adopts a conformation proximal to the site of catalytic dehydration only when the leaving group is present. We speculate that His-143 is likely to assume differing catalytic roles in each of its observed conformations. One conformation of His-143 positions the residue for the formation/hydrolysis of the covalent Schiff base intermediates, whereas the other conformation positions the residue for a role in the catalytic dehydration event. The fact that the shikimate pathway is absent from humans makes the enzymes of the pathway potential targets for the development of non-toxic antimicrobials. The structures and mechanistic insight presented here may inform the design of type I DHQD enzyme inhibitors.

  12. Appurtenance Influence on Type III Hanford Single-Shell Tank Structural Integrity - 12255

    International Nuclear Information System (INIS)

    The interim stabilized Hanford Single-Shell Tanks (SSTs) are currently undergoing a state of the art analysis to assess the structural integrity of the waste storage tanks, for cleanup and closure operations, considering their adverse thermal histories and an updated seismic hazard for the Hanford Site near Richland, Washington. The SSTs contain a variety of ancillary pits, piping, piping supports, risers, equipment, and penetrations known as appurtenances. These appurtenances may alter the structural response and ultimately could affect the structural integrity of the SSTs. An important challenge to the structural analysis of the SSTs is to determine the impact of these appurtenances on structural integrity. To achieve this, the various appurtenances were reviewed and a bounding appurtenance configuration for the SST Type III tanks was analyzed using finite element models for both thermal and operating loads as well as seismic loads. Tank structural demands from the finite element analyses were evaluated according to American Concrete Institute (ACI-349) code requirements to determine the tank structural integrity. The appurtenances configuration is found to increase the demand to capacity ratios in local regions near the appurtenances. Away from the appurtenances the influence on structural integrity is minor. The ACI-349-06 evaluation of the Type III SST bounding appurtenance configuration shows the tank is still structurally sound under all evaluated load combinations. When the appurtenance model D/C ratios were compared to those from the baseline axisymmetric model it was found that there were significant differences in the results, particularly under seismic loading conditions. This indicates that the effect of appurtenances on tank structural integrity should at least be considered in all SST AORs. (authors)

  13. Chromosomal localization and structure of the human type II IMP dehydrogenase gene

    Energy Technology Data Exchange (ETDEWEB)

    Glesne, D.; Huberman, E. [Chicago Univ., IL (United States). Dept. of Molecular Genetics and Cell Biology]|[Argonne National Lab., IL (United States); Collart, F. [Argonne National Lab., IL (United States); Varkony, T.; Drabkin, H. [Colorado Univ., Denver, CO (United States). Health Sciences Center

    1994-05-01

    We determined the chromosomal localization and structure of the gene encoding human type II inosine 5{prime}-monophosphate dehydrogenase (IMPDH, EC 1.1.1.205), an enzyme associated with cellular proliferation, malignant transformation, and differentiation. Using polymerase chain reaction (PCR) primers specific for type II IMPDH, we screened a panel of human-Chinese hamster cell somatic hybrids and a separate deletion panel of chromosome 3 hybrids and localized the gene to 3p21.1{yields}p24.2. Two overlapping yeast artificial chromosome clones containing the full gene for type II IMPDH were isolated and a physical map of 117 kb of human genomic DNA in this region of chromosome 3 was constructed. The gene for type II IMPDH was localized and oriented on this map and found to span no more than 12.5 kb.

  14. Mesothelin, Stereocilin, and Otoancorin are predicted to have superhelical structures with ARM-type repeats

    Directory of Open Access Journals (Sweden)

    Pastan Ira

    2009-01-01

    Full Text Available Abstract Background Mesothelin is a 40 kDa protein present on the surface of normal mesothelial cells and overexpressed in many human tumours, including mesothelioma and ovarian and pancreatic adenocarcinoma. It forms a strong and specific complex with MUC16, which is also highly expressed on the surface of mesothelioma and ovarian cancer cells. This binding has been suggested to be the basis of ovarian cancer metastasis. Knowledge of the structure of this protein will be useful, for example, in building a structural model of the MUC16-mesothelin complex. Mesothelin is produced as a precursor, which is cleaved by furin to produce the N-terminal half, which is called the megakaryocyte potentiating factor (MPF, and the C-terminal half, which is mesothelin. Little is known about the function of mesothelin and there is no information on its possible three-dimensional structure. Mesothelin has been reported to be homologous to the deafness-related inner ear proteins otoancorin and stereocilin, for neither of which the three-dimensional structure is known. Results The BLAST and PSI-BLAST searches confirmed that mesothelin and mesothelin precursor proteins are remotely homologous to stereocilin and otoancorin and more closely homologous to the hypothetical protein MPFL (MPF-like. Secondary structure prediction servers predicted a predominantly helical structure for both mesothelin and mesothelin precursor proteins and also for stereocilin and otoancorin. Three-dimensional structure prediction servers INHUB and I-TASSER produced structural models for mesothelin, which consisted of superhelical structures with ARM-type repeats in conformity with the secondary structure predictions. Similar ARM-type superhelical repeat structures were predicted by 3D-PSSM server for mesothelin precursor and for stereocilin and otoancorin proteins. Conclusion The mesothelin superfamily of proteins, which includes mesothelin, mesothelin precursor, megakaryocyte potentiating factor, MPFL, stereocilin and otoancorin, are predicted to have superhelical structures with ARM-type repeats. We suggest that all of these function as superhelical lectins to bind the carbohydrate moieties of extracellular glycoproteins.

  15. Hydrogen position, hydrogen bonding and hydroxide dynamics in the Cd(OH)Cl structure type

    International Nuclear Information System (INIS)

    Complete text of publication follows. The crystal structure of Cd(OH)Cl is already known since the single-crystal and powder diffraction investigations by Hoard and Grenko (1). It crystallizes in its own structure type which is intimately related to the layer structures of cadmium hydroxide and cadmium chloride. Although the isotypic structures of Ca(OH)Cl (2) and Sr(OH)Cl (3) have been examined, the hydrogen position of this structure type, however, is not yet completely clear. We performed single crystal diffraction of Cd(OH)Cl on a modern ?-CCD diffractometer, TOF neutron powder diffraction experiments with an annular cylindrical sample of Cd(OD)Cl, temperature dependent 2H-NMR-spectroscopy and quantum mechanical calculations to reinvestigate the crystal structure with full information about H-position, H-bonding and hydroxide dynamics. The results show that the hydrogen position is near a three-fold axis, that only small angle liberations occur and the amount of hydrogen bonding can be neglected. (author)

  16. Growth of equilibrium structures built from a large number of distinct component types.

    Science.gov (United States)

    Hedges, Lester O; Mannige, Ranjan V; Whitelam, Stephen

    2014-09-14

    We use simple analytic arguments and lattice-based computer simulations to study the growth of structures made from a large number of distinct component types. Components possess 'designed' interactions, chosen to stabilize an equilibrium target structure in which each component type has a defined spatial position, as well as 'undesigned' interactions that allow components to bind in a compositionally-disordered way. We find that high-fidelity growth of the equilibrium target structure can happen in the presence of substantial attractive undesigned interactions, as long as the energy scale of the set of designed interactions is chosen appropriately. This observation may help explain why equilibrium DNA 'brick' structures self-assemble even if undesigned interactions are not suppressed [Ke et al. Science, 338, 1177, (2012)]. We also find that high-fidelity growth of the target structure is most probable when designed interactions are drawn from a distribution that is as narrow as possible. We use this result to suggest how to choose complementary DNA sequences in order to maximize the fidelity of multicomponent self-assembly mediated by DNA. We also comment on the prospect of growing macroscopic structures in this manner. PMID:25005537

  17. Production of fine structures in type III solar radio bursts due to turbulent density profiles

    International Nuclear Information System (INIS)

    Magnetic reconnection events in the corona release energetic electron beams along open field lines, and the beams generate radio emission at multiples of the electron plasma frequency fp to produce type III solar radio bursts. Type III bursts often exhibit irregularities in the form of flux modulations with frequency and/or local temporal advances and delays, and a type IIIb burst represents the extreme case where a type III burst is fragmented into a chain of narrowband features called striae. Remote and in situ spacecraft measurements have shown that density turbulence is ubiquitous in the corona and solar wind, and often exhibits a Kolmogorov power spectrum. In this work, we numerically investigate the effects of one-dimensional macroscopic density turbulence (along the beam direction) on the behavior of type III bursts, and find that this turbulence produces stria-like fine structures in the dynamic spectra of both fp and 2 fp radiation. Spectral and temporal fine structures in the predicted type III emission are produced by variations in the scattering path lengths and group speeds of radio emission, and in the locations and sizes of emitting volumes. Moderate turbulence levels yield flux enhancements with much broader half-power bandwidths in fp than 2 fp emission, possibly explaining the often observed type IIIb-III harmonic pairs as being where intensifications in 2 fp radiation are not resolved observationally. Larger turbulence levels producing trough-peak regions in the plasma density profile may lead to broader, resolvable intensifications in 2 fp radiation, which may account for the type IIIb-IIIb pairs that are sometimes observed.

  18. Production of fine structures in type III solar radio bursts due to turbulent density profiles

    Energy Technology Data Exchange (ETDEWEB)

    Loi, Shyeh Tjing; Cairns, Iver H.; Li, Bo, E-mail: sloi5113@uni.sydney.edu.au [School of Physics, The University of Sydney, New South Wales 2006 (Australia)

    2014-07-20

    Magnetic reconnection events in the corona release energetic electron beams along open field lines, and the beams generate radio emission at multiples of the electron plasma frequency f{sub p} to produce type III solar radio bursts. Type III bursts often exhibit irregularities in the form of flux modulations with frequency and/or local temporal advances and delays, and a type IIIb burst represents the extreme case where a type III burst is fragmented into a chain of narrowband features called striae. Remote and in situ spacecraft measurements have shown that density turbulence is ubiquitous in the corona and solar wind, and often exhibits a Kolmogorov power spectrum. In this work, we numerically investigate the effects of one-dimensional macroscopic density turbulence (along the beam direction) on the behavior of type III bursts, and find that this turbulence produces stria-like fine structures in the dynamic spectra of both f{sub p} and 2 f{sub p} radiation. Spectral and temporal fine structures in the predicted type III emission are produced by variations in the scattering path lengths and group speeds of radio emission, and in the locations and sizes of emitting volumes. Moderate turbulence levels yield flux enhancements with much broader half-power bandwidths in f{sub p} than 2 f{sub p} emission, possibly explaining the often observed type IIIb-III harmonic pairs as being where intensifications in 2 f{sub p} radiation are not resolved observationally. Larger turbulence levels producing trough-peak regions in the plasma density profile may lead to broader, resolvable intensifications in 2 f{sub p} radiation, which may account for the type IIIb-IIIb pairs that are sometimes observed.

  19. Impact of varying soil structure on transport processes in different diagnostic horizons of three soil types

    Science.gov (United States)

    Kodešová, Radka; Vignozzi, Nadia; Rohošková, Marcela; Hájková, Tereza; Ko?árek, Martin; Pagliai, Marcello; Kozák, Josef; Šim?nek, Jirka

    2009-02-01

    When soil structure varies in different soil types and the horizons of these soil types, it has a significant impact on water flow and contaminant transport in soils. This paper focuses on the effect of soil structure variations on the transport of pesticides in the soil above the water table. Transport of a pesticide (chlorotoluron) initially applied on soil columns taken from various horizons of three different soil types (Haplic Luvisol, Greyic Phaeozem and Haplic Cambisol) was studied using two scenarios of ponding infiltration. The highest infiltration rate and pesticide mobility were observed for the Bt 1 horizon of Haplic Luvisol that exhibited a well-developed prismatic structure. The lowest infiltration rate was measured for the Bw horizon of Haplic Cambisol, which had a poorly developed soil structure and a low fraction of large capillary pores and gravitational pores. Water infiltration rates were reduced during the experiments by a soil structure breakdown, swelling of clay and/or air entrapped in soil samples. The largest soil structure breakdown and infiltration decrease was observed for the Ap horizon of Haplic Luvisol due to the low aggregate stability of the initially well-aggregated soil. Single-porosity and dual-permeability (with matrix and macropore domains) flow models in HYDRUS-1D were used to estimate soil hydraulic parameters via numerical inversion using data from the first infiltration experiment. A fraction of the macropore domain in the dual-permeability model was estimated using the micro-morphological images. Final soil hydraulic parameters determined using the single-porosity and dual-permeability models were subsequently used to optimize solute transport parameters. To improve numerical inversion results, the two-site sorption model was also applied. Although structural changes observed during the experiment affected water flow and solute transport, the dual-permeability model together with the two-site sorption model proved to be able to approximate experimental data.

  20. The structure of the R8 term in type IIB string theory

    International Nuclear Information System (INIS)

    Based on the structure of the on-shell linearized superspace of type IIB supergravity, we argue that there is a non-BPS 16 derivative interaction in the effective action of type IIB string theory of the form (t8t8R4)2, which we call the R8 interaction. It lies in the same supermultiplet as the G8R4 interaction. Using the Kawai–Lewellen–Tye relation, we analyze the structure of the tree level eight-graviton scattering amplitude in the type IIB theory, which leads to the R8 interaction at the linearized level. This involves an analysis of color-ordered multi-gluon disc amplitudes in the type I theory, which shows an intricate pole structure and transcendentality consistent with various other interactions. Considerations of S-duality show that the R8 interaction receives non-analytic contributions in the string coupling at one and two loops. Apart from receiving perturbative contributions, we show that the R8 interaction receives a non-vanishing contribution in the one D-instanton-anti-instanton background at leading order in the weak coupling expansion. (paper)

  1. Integrability of and differential–algebraic structures for spatially 1D hydrodynamical systems of Riemann type

    International Nuclear Information System (INIS)

    Highlights: • A new differential–algebraic–geometric approach for testing integrability is described. • The approach is applied to a generalized Riemann type hydrodynamic system. • The approach is applied to a generalized Ostrovsky–Vakhnenko system. • The approach is applied to a new two-component Burgers type hydrodynamic system. -- Abstract: A differential–algebraic approach to studying the Lax integrability of a generalized Riemann type hydrodynamic hierarchy is revisited and a new Lax representation is constructed. The related bi-Hamiltonian integrability and compatible Poissonian structures of this hierarchy are also investigated using gradient-holonomic and geometric methods. The complete integrability of a new generalized Riemann hydrodynamic system is studied via a novel combination of symplectic and differential–algebraic tools. A compatible pair of polynomial Poissonian structures, a Lax representation and a related infinite hierarchy of conservation laws are obtained. In addition, the differential–algebraic approach is used to prove the complete Lax integrability of the generalized Ostrovsky–Vakhnenko and a new Burgers type system, and special cases are studied using symplectic and gradient-holonomic tools. Compatible pairs of polynomial Poissonian structures, matrix Lax representations and infinite hierarchies of conservation laws are derived

  2. Crystal structure of Manduca sexta prophenoloxidase provides insights into the mechanism of type 3 copper enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Li, Yongchao; Wang, Yang; Jiang, Haobo; Deng, Junpeng; (OKLU)

    2010-02-22

    Arthropod phenoloxidase (PO) generates quinones and other toxic compounds to sequester and kill pathogens during innate immune responses. It is also involved in wound healing and other physiological processes. Insect PO is activated from its inactive precursor, prophenoloxidase (PPO), by specific proteolysis via a serine protease cascade. Here, we report the crystal structure of PPO from a lepidopteran insect at a resolution of 1.97 {angstrom}, which is the initial structure for a PPO from the type 3 copper protein family. Manduca sexta PPO is a heterodimer consisting of 2 homologous polypeptide chains, PPO1 and PPO2. The active site of each subunit contains a canonical type 3 di-nuclear copper center, with each copper ion coordinated with 3 structurally conserved histidines. The acidic residue Glu-395 located at the active site of PPO2 may serve as a general base for deprotonation of monophenolic substrates, which is key to the ortho-hydroxylase activity of PO. The structure provides unique insights into the mechanism by which type 3 copper proteins differ in their enzymatic activities, albeit sharing a common active center. A drastic change in electrostatic surface induced on cleavage at Arg-51 allows us to propose a model for localized PPO activation in insects.

  3. Precision photonic band structure calculation of Abrikosov periodic lattice in type-II superconductors

    International Nuclear Information System (INIS)

    We have performed a numerical solution for band structure of an Abrikosov vortex lattice in type-II superconductors forming a periodic array in two dimensions for applications of incorporating the photonic crystals concept into superconducting materials with possibilities for optical electronics. The implemented numerical method is based on the extensive numerical solution of the Ginzburg-Landau equation for calculating the parameters of the two-fluid model and obtaining the band structure from the permittivity, which depends on the above parameters and the frequency. This is while the characteristics of such crystals highly vary with an externally applied static normal magnetic field, leading to nonlinear behavior of the band structure, which also has nonlinear dependence on the temperature. The similar analysis for every arbitrary lattice structure is also possible to be developed by this approach as presented in this work. We also present some examples and discuss the results

  4. A new tetragonal structure type for Li2B2C.

    Science.gov (United States)

    Pavlyuk, Volodymyr; Milashys, Viktoriya; Dmytriv, Grygoriy; Ehrenberg, Helmut

    2015-01-01

    The ternary dilithium diboron carbide, Li2B2C (tetragonal, space group P-4m2, tP10), crystallizes as a new structure type and consists of structural fragments which are typical for structures of elemental lithium and boron or binary borocarbide B13C2. The symmetries of the occupied sites are .m. and 2mm. for the B and C atoms, and -4m2 and 2mm. for the Li atoms. The coordination polyhedra around the Li atoms are cuboctahedra and 15-vertex distorted pseudo-Frank-Kasper polyhedra. The environment of the B atom is a ten-vertex polyhedron. The nearest neighbours of the C atom are two B atoms, and this group is surrounded by a deformed cuboctahedron with one centred lateral facet. Electronic structure calculations using the TB-LMTO-ASA method reveal strong B...C and B...B interactions. PMID:25567573

  5. The environment effect on creep fatigue strength for FBR high temperature structural material, Type 304 steel

    International Nuclear Information System (INIS)

    In order to rationalize FBR high temperature structural design, the creep fatigue strength of Type 304 stainless steel for FBR main vessel was investigated in air and vacuum. The results obtained were as follows: Independent of strain wave forms, creep fatigue lives in vacuum were longer than those in air, and especially strain wave forms of fatigue damage type had noticeably longer lives. Also, a tendency to have too much longer lives at low strain level being important for real plant condition was shown. At last, it was confirmed that cyclic deformation behavior in vacuum was coincident with that in air. (author)

  6. Crystal structure of the Yersinia type III secretion protein YscE

    Energy Technology Data Exchange (ETDEWEB)

    Phan, Jason; Austin, Brian P.; Waugh, David S. (NIH)

    2010-12-06

    The plague-causing bacterium Yersinia pestis utilizes a contact-dependent (type III) secretion system (T3SS) to transport virulence factors from the bacterial cytosol directly into the interior of mammalian cells where they interfere with signal transduction pathways that mediate phagocytosis and the inflammatory response. The type III secretion apparatus is composed of 20-25 different Yersinia secretion (Ysc) proteins. We report here the structure of YscE, the smallest Ysc protein, which is a dimer in solution. The probable mode of oligomerization is discussed.

  7. Four types of interference competition and their impacts on the ecology and evolution of size-structured populations and communities

    DEFF Research Database (Denmark)

    Zhang, Lai; Andersen, Ken Haste; Dieckmann, Ulf; Brännström, Åke Ke

    2015-01-01

    We investigate how four types of interference competition - which alternatively affect foraging, metabolism, survival, and reproduction - impact the ecology and evolution of size-structured populations. Even though all four types of interference competition reduce population biomass, interference...

  8. Band stop vibration suppression using a passive X-shape structured lever-type isolation system

    Science.gov (United States)

    Liu, Chunchuan; Jing, Xingjian; Chen, Zhaobo

    2016-02-01

    In the paper, band-stop vibration suppression property using a novel X-shape structured lever-type isolation system is studied. The geometrical nonlinear property of an X-shape supporting structure is used to improve the band-stop characteristics in the low frequency range of the lever-type vibration isolator. With the dynamics modeling of this hybrid structural system, it is shown that the proposed hybrid vibration system has very beneficial nonlinear stiffness and damping properties which are helpful to achieve much wider stop bandwidth. Theoretical results demonstrate that the anti-resonant frequencies, width and magnitude of the stop band can all be flexibly designed with structural parameters, and the parameters of the X-shape supporting structure are very critical for designing the band-stop frequency to achieve excellent low-frequency isolation performance. The results in the study provide a new approach to the design of the passive vibration suppression system in the low frequency region.

  9. Identify Structural Flaw Location and Type with an Inverse Algorithm of Resonance Inspection

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Wei; Lai, Canhai; Sun, Xin

    2015-10-20

    To evaluate the fitness-for-service of a structural component and to quantify its remaining useful life, aging and service-induced structural flaws must be quantitatively determined in service or during scheduled maintenance shutdowns. Resonance inspection (RI), a non-destructive evaluation (NDE) technique, distinguishes the anomalous parts from the good parts based on changes in the natural frequency spectra. Known for its numerous advantages, i.e., low inspection cost, high testing speed, and broad applicability to complex structures, RI has been widely used in the automobile industry for quality inspection. However, compared to other contemporary direct visualization-based NDE methods, a more widespread application of RI faces a fundamental challenge because such technology is unable to quantify the flaw details, e.g. location, dimensions, and types. In this study, the applicability of a maximum correlation-based inverse RI algorithm developed by the authors is further studied for various flaw cases. It is demonstrated that a variety of common structural flaws, i.e. stiffness degradation, voids, and cracks, can be accurately retrieved by this algorithm even when multiple different types of flaws coexist. The quantitative relations between the damage identification results and the flaw characteristics are also developed to assist the evaluation of the actual state of health of the engineering structures.

  10. Crystal structure of a copper-transporting PIB-type ATPase

    DEFF Research Database (Denmark)

    Gourdon, Pontus Emanuel; Liu, Xiang-Yu; Skjørringe, Tina; Morth, J Preben; Møller, Lisbeth Birk; Pedersen, Bjørn Panyella; Nissen, Poul

    2011-01-01

    Heavy-metal homeostasis and detoxification is crucial for cell viability. P-type ATPases of the class IB (PIB) are essential in these processes, actively extruding heavy metals from the cytoplasm of cells. Here we present the structure of a PIB-ATPase, a Legionella pneumophila CopA Cu(+)-ATPase, in a copper-free form, as determined by X-ray crystallography at 3.2 Å resolution. The structure indicates a three-stage copper transport pathway involving several conserved residues. A PIB-specific tran...

  11. Determination of height of transfer unit at hydrogen isotopic distillation on B7 type structured packing

    International Nuclear Information System (INIS)

    Due to the low pressure drop which that the structured packing introduces it is often used in the case of distillations under vacuum and of the mixture separation when the desired component is present in very low concentration, for example the water, hydrogen and oxygen isotopic distillation. The paper presents a model for the determination of height of transfer unit at hydrogen isotopic distillation plant with structured B7 type packing. The values of HTU calculated with the analogy model between the heat, momentum and mass transfer are compared with the experimental data. (authors)

  12. Height of transfer unit determination at hydrogen isotopic distillation on structured packing, B7 type

    International Nuclear Information System (INIS)

    Due to the low pressure drop that it introduces, the structured packing is often used in the case of distillations under vacuum and of the mixture separation when the desired component is founded in very low concentration, for example the water, hydrogen and oxygen isotopic distillation. The paper presents a model for the determination of height of transfer unit at hydrogen isotopic distillation plant with structured B7 type packing. The values of the height of a transfer unit (HTU) calculated with the analogy model between the heat, momentum and mass transfer are compared with the experimental data

  13. Height of transfer unit determination at hydrogen isotopic distillation on B7 type structured packing

    International Nuclear Information System (INIS)

    Due to the low pressure drop that it introduces, the structured packing is often used in the case of distillation under vacuum and of the mixture separation when the desired component is found in very low concentration, for example the water, hydrogen and oxygen isotopic distillation. The paper presents a model for the determination of height of transfer unit at hydrogen isotopic distillation plant with structured B7 type packing. The values of HTU calculated with the analogy model between the heat, momentum and mass transfer are compared with the experimental data. (authors)

  14. Crystallographic structure of porcine adenovirus type 4 fiber head and galectin domains

    OpenAIRE

    Kahn, Richard; CURIEL, DAVID T.; Glasgow, Joel N.; Raaij, Mark J. van

    2010-01-01

    Adenovirus isolate NADC-1, a strain of porcine adenovirus type 4, has a fiber containing an N-terminal virus attachment region, shaft and head domains, and a C-terminal galectin domain connected to the head by an RGD-containing sequence. The crystal structure of the head domain is similar to previously solved adenovirus fiber head domains, but specific residues for binding the coxsackievirus and adenovirus receptor (CAR), CD46, or sialic acid are not conserved. The structure of the galectin d...

  15. Crystallographic Structure of Porcine Adenovirus Type 4 Fiber Head and Galectin Domains?

    OpenAIRE

    Guardado-Calvo, Pablo; Muñoz, Eva M.; Llamas-Saiz, Antonio L.; Fox, Gavin C.; Kahn, Richard; CURIEL, DAVID T.; Glasgow, Joel N.; Raaij, Mark J. van

    2010-01-01

    Adenovirus isolate NADC-1, a strain of porcine adenovirus type 4, has a fiber containing an N-terminal virus attachment region, shaft and head domains, and a C-terminal galectin domain connected to the head by an RGD-containing sequence. The crystal structure of the head domain is similar to previously solved adenovirus fiber head domains, but specific residues for binding the coxsackievirus and adenovirus receptor (CAR), CD46, or sialic acid are not conserved. The structure of the galectin d...

  16. Structural and Electrical Properties of P--Type ZnO Thin Films

    International Nuclear Information System (INIS)

    The codoped ZnO thin film were deposited by DC magnetron sputtering on silicon (111) followed by annealing treatment at 200 deg. C to 600 deg. C for 1 hour in nitrogen and oxygen gas mixture. P-type conduction of Al-N codoped ZnO thin films were obtained at 300 deg. C with the lowest resistivity of 3.412x10-3 ?·cm and highest carrier concentration of 1.54x1022 cm-3. Structural investigation was carried out by atomic force microscope (AFM) and X-ray diffraction (XRD). Results showed that heat treatment had influenced the structure of the films

  17. Ion-conduction mechanisms in NaSICON-type membranes for energy storage and utilization

    Energy Technology Data Exchange (ETDEWEB)

    McDaniel, Anthony H. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Sandia National Laboratories, Albuquerque, NM (United States); Ihlefeld, Jon F. [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Sandia National Laboratories, Albuquerque, NM (United States); Bartelt, Norman Charles [Sandia National Laboratories (SNL-CA), Livermore, CA (United States); Sandia National Laboratories, Albuquerque, NM (United States)

    2015-10-01

    Next generation metal-ion conducting membranes are key to developing energy storage and utilization technologies like batteries and fuel ce lls. Sodium super-ionic conductors (aka NaSICON) are a class of compounds with AM 1 M 2 (PO 4 ) 3 stoichiometry where the choice of "A" and "M" cation varies widely. This report, which de scribes substitutional derivatives of NZP (NaZr 2 P 3 O 12 ), summarizes the accomplishments of a Laboratory D irected Research and Development (LDRD) project to analyze transport mec hanisms using a combination of in situ studies of structure, composition, and bonding, com bined with first principles theory and modeling. We developed an experimental platform and applied methods, such as synchrotron- based X-ray spectroscopies, to probe the electronic structure of compositionally well-controlled NaSICON films while in operation ( i.e ., conducting Na ions exposed to oxygen or water va por atmospheres). First principles theory and modeling were used to interpret the experimental observations and develop an enhanced understanding of atomistic processes that give rise to, and affect, ion conduction.

  18. Structural modeling of dahlia-type single-walled carbon nanohorn aggregates by molecular dynamics.

    Science.gov (United States)

    Hawelek, L; Brodka, A; Dore, John C; Hannon, Alex C; Iijima, S; Yudasaka, M; Ohba, T; Kaneko, K; Burian, A

    2013-09-19

    The structure of dahlia-type single-walled carbon nanohorn aggregates has been modeled by classical molecular dynamics simulations, and the validity of the model has been verified by neutron diffraction. Computer-generated models consisted of an outer part formed from single-walled carbon nanohorns with diameters of 20-50 Å and a length of 400 Å and an inner turbostratic graphite-like core with a diameter of 130 Å. The diffracted intensity and the pair correlation function computed for such a constructed model are in good agreement with the neutron diffraction experimental data. The proposed turbostratic inner core explains the occurrence of the additional (002) and (004) graphitic peaks in the diffraction pattern of the studied sample and provides information about the interior structure of the dahlia-type aggregates. PMID:23978218

  19. Structure and proton conduction in pyrochlore-type antimonic acid. A neutron diffraction study

    International Nuclear Information System (INIS)

    The structure of pyrochlore-type antimonic acid, HSbO3·0.5H2O, has been investigated using powder diffraction of neutrons. The structure (space group Fd3m) contains an [Sb2O62-] framework, with interstitial oxygens present as a mixture of H2O and H3O+. Three H-atom sites have been identified, (1) close to the [Sb2O62-] framework in hydroxyl groups (Sb-OH), (2) H in water molecules H-bonded to framework hydroxyls, and (3) H in H3O+ ions H-bonded to O-atoms of the intercavity windows. An intraframework equilibrium of the type Sb-OH+H2OSb-O-+H3O+ provides the mechanism for intracavity chemical exchange and proton conduction

  20. Prediction, conservation analysis, and structural characterization of mammalian mucin-type O-glycosylation sites

    DEFF Research Database (Denmark)

    Julenius, Karin; Mølgaard, Anne; Gupta, Ramneek; Brunak, Søren

    2005-01-01

    O-GalNAc-glycosylation is one of the main types of glycosylation in mammalian cells. No consensus recognition sequence for the O-glycosyltransferases is known, making prediction methods necessary to bridge the gap between the large number of known protein sequences and the small number of proteins...... experimentally investigated with regard to glycosylation status. From O-GLYCBASE a total of 86 mammalian proteins experimentally investigated for in vivo O-GalNAc sites were extracted. Mammalian protein homolog comparisons showed that a glycosylated serine or threonine is less likely to be precisely conserved...... than a nonglycosylated one. The Protein Data Bank was analyzed for structural information, and 12 glycosylated structures were obtained. All positive sites were found in coil or turn regions. A method for predicting the location for mucin-type glycosylation sites was trained using a neural network...

  1. Real non-abelian mixed Hodge structures for schematic homotopy types of quasi-projective varieties

    CERN Document Server

    Pridham, J P

    2011-01-01

    The relative Malcev homotopy type of a quasi-projective variety carries a canonical non-positively weighted algebraic mixed twistor structure (MTS), provided we restrict to extensions of local systems with trivial monodromy around the components of the divisor. This can be enriched to an analytic mixed Hodge structure (MHS), which becomes algebraic if we restrict to extensions of local systems underlying VHS. We then show that every non-positively weighted MHS or MTS on homotopy types admits a canonical splitting over SL_2. For smooth varieties, this allows us to characterise the MHS or MTS in terms of the Gysin spectral sequence, together with the monodromy action at the Archimedean place. It also means that the relative Malcev homotopy groups carry canonical MTS or MHS.

  2. Optical properties of crystals with incommensurate structure of Lifshitz’s type

    Directory of Open Access Journals (Sweden)

    O.G.Vlokh

    2000-09-01

    Full Text Available A review of optical properties of A2BX4 group crystals with incommensurate modulated structure of Lifshitz’s type a.i. crystals, which characterize nonequitranslation unit cell of high temperature and ordering - low temperature phases is done. The characteristics features of birefringence, optical activity, light absorption and the effects induced by the external influences (temperature, pressure, electric fields and mechanical stresses, X-ray radiation, as well as their gradients are considered in this paper. It is shown that different types of interaction between defects or impurities and structural elements (pinning, viscous interaction, nucleation and annihilation of phase solitons or commensurate-incommensurate states (so-called discommensuration manifest themselves in the anomalies of optical phenomena in the incommensurate phases.

  3. From Proteomics to Structural Studies of Cytosolic/Mitochondrial-Type Thioredoxin Systems in Barley Seeds

    DEFF Research Database (Denmark)

    Shahpiri, Azar; Svensson, Birte; Finnie, Christine

    2009-01-01

    Thioredoxins (Trx) are ubiquitous proteins that participate in thiol disulfide reactions via two active site cysteine residues, allowing Trx to reduce disulfide bonds in target proteins. Recent progress in proteome analysis has resulted in identification of a wide range of potential target proteins...... for Trx, indicating that Trx plays a key role in several aspects of cell metabolism. In contrast to other organisms, plants contain multiple forms of Trx that are classified based on their primary structures and sub-cellular localization. The reduction of cytosolic and mitochondrial types of Trx is...... dependent on NADPH and catalyzed by NADPH-dependent thioredoxin reductase (NTR). In barley, two isoforms each of Trx and NTR have been identified and investigated using proteomics, gene expression, and structural studies. This review outlines the diverse roles suggested for cytosolic/mitochondrial-type Trx...

  4. Crystal Structure of a Putative HTH-Type Transcriptional Regulator yxaF from Bacillus subtilis

    International Nuclear Information System (INIS)

    The New York Structural GenomiX Research Consortium (NYSGXRC) has selected the protein coded by yxaF gene from Bacillus subtilis as a target for structure determination. The yxaF protein has 191 residues with a molecular mass of 21 kDa and had no sequence homology to any structure in the Protein Data Bank (PDB) at the time of target selection. We aimed to elucidate the three-dimensional structure for the putative protein yxaF to better understand the relationship between protein sequence, structure, and function. This protein is annotated as a putative helix-turn-helix (HTH) type transcriptional regulator. Many transcriptional regulators like TetR and QacR use a structurally well-defined DNA-binding HTH motif to recognize the target DNA sequences. DNA-HTH motif interactions have been extensively studied. As the HTH motif is structurally conserved in many regulatory proteins, these DNA-protein complexes show some similarity in DNA recognition patterns. Many such regulatory proteins have a ligand-binding domain in addition to the DNA-binding domain. Structural studies on ligand-binding regulatory proteins provide a wealth of information on ligand-, and possibly drug-, binding mechanisms. Understanding the ligand-binding mechanism may help overcome problems with drug resistance, which represent increasing challenges in medicine. The protein encoded by yxaF, hereafter called T1414, shows fold similar to QacR repressor and TetR/CamR repressor and possesses putative DNA and ligand-binding domains. Here, we report the crystal structure of T1414 and compare it with structurally similar drug and DNA-binding proteins

  5. Structural Comparison of n-type and p-type LaAlO3/SrTiO3 Interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bell, Christopher

    2011-08-19

    Using a surface x-ray diffraction technique, we investigated the atomic structure of two types of interfaces between LaAlO{sub 3} and SrTiO{sub 3}, that is, p-type (SrO/AlO{sub 2}) and n-type (TiO{sub 2}/LaO) interfaces. Our results demonstrate that the SrTiO{sub 3} in the sample with the n-type interface has a large polarized region, while that with the p-type interface has a limited polarized region. In addition, the atomic intermixing was observed to extend deeper into STO substrate at the n-type interface than at the p-type. These differences result in different degrees of band bending, which likely contributes to the striking difference in electrical conductivity between the two types of interfaces.

  6. Flat structure for the simple elliptic singularity of type $\\widetilde {\\bf E_6}$ and Jacobi form

    OpenAIRE

    Satake, Ikuo

    1993-01-01

    In order to construct the inverse mapping of the period mapping for the primitive form for the semi-universal deformation of a simple elliptic singularity, K.Saito introduced in [5] the ``flat structure'' for the extended affine root system. In section 3, we construct explicitly the flat theta invariants in the case of type $E_6$ using the Jacobi form introduced by Wirthm\\"uller [7]. Combining the results of Kato [3], Noumi [4] (explicit description of the flat coordinates),...

  7. Efficiency of different forest types in carbon storage depends on their internal structure

    OpenAIRE

    Iuliana F. Gheorghe; Iovu A. Biri?; Cristina M. Valcu

    2010-01-01

    Forest vegetation is a key factor in the maintenance of global carbon cycle balance under the present climate change conditions. Forest ecosystems are both buffers against extreme climatic events accompanying climate change and carbon sinks diminishing the environmental impact of anthropogenic greenhouse gas emissions. We investigated the influence of stand structure and site characteristics on the productivity and carbon storage capacity of temperate forest types. Predictors of species produ...

  8. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg

    2014-01-01

    Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis1. In prokaryotes and photosynthetic eukaryotes, Zn2+-transporting P-type ATPases of class IB (ZntA) are crucial for cellular redistribution and detoxification of Zn2+ and related elements2, 3. Here we present crystal structures representing the phosphoenzyme ground state (E2P) and a dephosphorylation intermediate (E2·Pi) of ZntA from Shigella sonnei, determined at 3.2 Å and 2.7 Å resolution, respectively. The structures reveal a similar fold to Cu+-ATPases, with an amphipathic helix at the membrane interface. A conserved electronegative funnel connects this region to the intramembranous high-affinity ion-binding site and may promote specific uptake of cellular Zn2+ ions by the transporter. The E2P structure displays a wide extracellular release pathway reaching the invariant residues at the high-affinity site, including C392, C394 and D714. The pathway closes in the E2·Pi state, in which D714 interacts with the conserved residue K693, which possibly stimulates Zn2+ release as a built-in counter ion, as has been proposed for H+-ATPases. Indeed, transport studies in liposomes provide experimental support for ZntA activity without counter transport. These findings suggest a mechanistic link between PIB-type Zn2+-ATPases and PIII-type H+-ATPases and at the same time show structural features of the extracellular release pathway that resemble PII-type ATPases such as the sarcoplasmic/endoplasmic reticulum Ca2+-ATPase4, 5 (SERCA) and Na+, K+-ATPase6. These findings considerably increase our understanding of zinc transport in cells and represent new possibilities for biotechnology and biomedicine.

  9. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg

    2014-01-01

    Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis. In prokaryotes and photosynthetic eukaryotes, Zn(2+)-transporting P-type ATPases of class IB (ZntA) are crucial for cellular redistribution and detoxification of Zn(2+) and related elements. Here we present crystal structures representing the phosphoenzyme ground state (E2P) and a dephosphorylation intermediate (E2·Pi) of ZntA from Shigella sonnei, determined at 3.2 Å and 2.7 Å resolution, respectively. The structures reveal a similar fold to Cu(+)-ATPases, with an amphipathic helix at the membrane interface. A conserved electronegative funnel connects this region to the intramembranous high-affinity ion-binding site and may promote specific uptake of cellular Zn(2+) ions by the transporter. The E2P structure displays a wide extracellular release pathway reaching the invariant residues at the high-affinity site, including C392, C394 and D714. The pathway closes in the E2·Pi state, in which D714 interacts with the conserved residue K693, which possibly stimulates Zn(2+) release as a built-in counter ion, as has been proposed for H(+)-ATPases. Indeed, transport studies in liposomes provide experimental support for ZntA activity without counter transport. These findings suggest a mechanistic link between PIB-type Zn(2+)-ATPases and PIII-type H(+)-ATPases and at the same time show structural features of the extracellular release pathway that resemble PII-type ATPases such as the sarcoplasmic/endoplasmic reticulum Ca(2+)-ATPase (SERCA) and Na(+), K(+)-ATPase. These findings considerably increase our understanding of zinc transport in cells and represent new possibilities for biotechnology and biomedicine.

  10. A Multilocus Sequence Typing Scheme Implies Population Structure and Reveals Several Putative Novel Achromobacter Species

    OpenAIRE

    Spilker, Theodore; Vandamme, Peter; LiPuma, John J.

    2012-01-01

    The genus Achromobacter currently is comprised of seven species, including Achromobacter xylosoxidans, an opportunistic and nosocomial pathogen that displays broad-spectrum antimicrobial resistance and is recognized as causing chronic respiratory tract infection in persons with cystic fibrosis (CF). To enable strain typing for global epidemiologic investigations, to clarify the taxonomy of “Achromobacter-like” strains, and to elucidate the population structure of this genus, we developed a ge...

  11. Structure and Composition of Protein Bodies from Wild-Type and High-Lysine Barley Endosperm

    DEFF Research Database (Denmark)

    Ingversen, J.

    1975-01-01

    Protein bodies were isolated from 13 and 28 day old endosperms of barley mutant 1508 and its wild type, Bomi barley. The fine structure of the isolated protein bodies was determined by electron microscopy, and the proteins present in the preparations characterized by amino-acid analysis and SDS-p...... is suggested that the homogeneous protein body component represents a storage organelle with a high concentration of prolamines, and the granular component a storage organelle with a high concentration of glutelins....

  12. Physicochemical and structural characteristics of HEU-type zeolitic tuff treated by hydrochloric acid

    OpenAIRE

    MAGDALENA TOMASEVIC-CANOVIC; JOVAN LEMIC; ALEKSANDRA DAKOVIC; VERA DONDUR; ANA RADOSAVLJEVIC-MIHAJLOVIC

    2004-01-01

    Samples of natural HEU-type zeolites clinoptilolite-Ca, from the Novakovici deposit (near Prijedor, Bosnia and Herzegovina) were treated with the hydrochloric acid of various concentrations (from 10-3 M to 2 M). Zeolitic tuffs before and after the acid treatment were examined using IR, XRPD, and chemical analyses. The changes in the crystal structure of acid treated samples showed a significant reduction in the crystallinity of zeolitic tuffs (6070 %), which were effected by hydrochloric aci...

  13. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg; Meloni, Gabriele; Autzen, Henriette Elisabeth; Andersson, Magnus; Klymchuk, Tetyana; Nielsen, Anna Marie; Rees, Douglas C; Nissen, Poul; Gourdon, Pontus

    2014-01-01

    Zinc is an essential micronutrient for all living organisms. It is required for signalling and proper functioning of a range of proteins involved in, for example, DNA binding and enzymatic catalysis1. In prokaryotes and photosynthetic eukaryotes, Zn2+-transporting P-type ATPases of class IB (ZntA) are crucial for cellular redistribution and detoxification of Zn2+ and related elements2, 3. Here we present crystal structures representing the phosphoenzyme ground state (E2P) and a dephosphorylation...

  14. DG-FEM solution for nonlinear wave-structure interaction using Boussinesq-type equations

    DEFF Research Database (Denmark)

    Engsig-Karup, Allan Peter; Hesthaven, Jan; Bingham, Harry B.; Warburton, T.

    2008-01-01

    We present a high-order nodal Discontinuous Galerkin Finite Element Method (DG-FEM) solution based on a set of highly accurate Boussinesq-type equations for solving general water-wave problems in complex geometries. A nodal DG-FEM is used for the spatial discretization to solve the Boussinesq equations in complex and curvilinear geometries which amends the application range of previous numerical models that have been based on structured Cartesian grids. The Boussinesq method provides the basis f...

  15. Multi-scale (FE2) analysis of material failure in cement/aggregate-type composite structures

    OpenAIRE

    Oliver Olivella, Xavier; Caicedo, Manuel Alejandro; Roubin, Emmanuel; Hernández Ortega, Joaquín Alberto; Huespe, Alfredo Edmundo

    2014-01-01

    The work propases a FP multiscale approach to computational modeling of material failure in concreteMlike structures, made of cement/aggregate-type composite materials. Keeping the approach in a classical homogenization setting, a multiscale model is proposed, which naturally provides a microscopic length-scale to be exported to the macrostructure. There, this length scale is used as regularization parameter in the context of the Continuum Strong Discontinuity Approach to material failure, an...

  16. GP3 is a structural component of the PRRSV type II (US) virion

    International Nuclear Information System (INIS)

    Glycoprotein 3 (GP3) is a highly glycosylated PRRSV envelope protein which has been reported as being present in the virions of PRRSV type I, while missing in the type II PRRSV (US) virions. We herein present evidence that GP3 is indeed incorporated in the virus particles of a North American strain of PRRSV (FL12), at a density that is consistent with the minor structural role assigned to GP3 in members of the Arterivirus genus. Two 15aa peptides corresponding to two different immunodominant linear epitopes of GP3 derived from the North American strain of PRRSV (FL12) were used as antigen to generate a rabbit monospecific antiserum to this protein. The specificity of this anti-GP3 antiserum was confirmed by radioimmunoprecipitation (RIP) assay using BHK-21 cells transfected with GP3 expressing plasmid, MARC-145 cells infected with FL12 PRRSV, as well as by confocal microscopy on PRRSV-infected MARC-145 cells. To test if GP3 is a structural component of the virion, 35S-labelled PRRSV virions were pelleted through a 30% sucrose cushion, followed by a second round of purification on a sucrose gradient (20-60%). Virions were detected in specific gradient fractions by radioactive counts and further confirmed by viral infectivity assay in MARC 145 cells. The GP3 was detected in gradient fractions containing purified virions by RIP using anti-GP3 antiserum. Predictably, the GP3 was less abundant in purified virions than other major structural envelope proteins such as GP5 and M. Further evidence of the presence of GP3 at the level of PRRSV FL12 envelope was obtained by immunogold staining of purified virions from the supernatant of infected cells with anti-GP3 antiserum. Taken together, these results indicate that GP3 is a minor structural component of the PRRSV type II (FL12 strain) virion, as had been previously described for PRRSV type I.

  17. Direct Structure Determination of Multilayered Membrane-Type Systems Which Contain Fluid Layers

    Science.gov (United States)

    Worthington, C. R.; King, G. I.; McIntosh, T. J.

    1973-01-01

    The theory of direct methods of structure analysis in the case of multilayered membrane-type systems which contain fluid layers is described. Diffraction formulas for this kind of analysis are derived. Deconvolution methods are used when the centrosymmetrical unit cells contain wide fluid layers. When the membrane systems contain narrow fluid layers, other direct methods are used. These direct methods involve computing either the Fourier series representations or the sampling theorem expressions. PMID:4704487

  18. Optical properties of crystals with incommensurate structure of Lifshitz’s type

    OpenAIRE

    O.G.Vlokh

    2000-01-01

    A review of optical properties of A2BX4 group crystals with incommensurate modulated structure of Lifshitz’s type a.i. crystals, which characterize nonequitranslation unit cell of high temperature and ordering - low temperature phases is done. The characteristics features of birefringence, optical activity, light absorption and the effects induced by the external influences (temperature, pressure, electric fields and mechanical stresses, X-ray radiation, as well as their gradients) are consid...

  19. EVALUATION OF STRUCTURAL WOOD GLUED JOINT QUALITY, DEPENDING ON SELECTED TYPE OF AHDESIVE

    OpenAIRE

    ANNA BENESOVA; JAN VANEREK

    2012-01-01

    Structural wood glued joints are used to bond components of lamellar oragglomerated load-bearing members. Factor that influences the quality of the joint isthe sensitivity of wood mass to ambient humidity changes. Cyclic wetting and dryingof the timber leads to its volume changes and causes shear stress in the area of thebond line. Therefore, selected types of adhesives were tested according to a standardEN 302-1. In addition to shear strength assessment, a wood failure of specimens wasobserv...

  20. Crystal Structure of Hcp from Acinetobacter baumannii: A Component of the Type VI Secretion System

    OpenAIRE

    Ruiz, Federico M.; Santillana, Elena; Spínola-Amilibia, Mercedes; Torreira, Eva; Culebras, Esther; Romero, Antonio

    2015-01-01

    The type VI secretion system (T6SS) is a bacterial macromolecular machine widely distributed in Gram-negative bacteria, which transports effector proteins into eukaryotic host cells or other bacteria. Membrane complexes and a central tubular structure, which resembles the tail of contractile bacteriophages, compose the T6SS. One of the proteins forming this tube is the hemolysin co-regulated protein (Hcp), which acts as virulence factor, as transporter of effectors and as a chaperone. In this...

  1. Rosuvastatin Alleviates Type 2 Diabetic Atrial Structural and Calcium Channel Remodeling.

    Science.gov (United States)

    Pan, Yilong; Li, Bin; Wang, Jingzhuo; Li, Xiaodong

    2016-01-01

    Recent evidence has indicated that type 2 diabetes mellitus is related to an increased risk of atrial arrhythmias, which might result from atrial structural and electrical remodeling. Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase (statins), known as lipid-lowering agents, have been shown to exert antiarrhythmic effects both in experimental models and in humans. In this study, we postulate that atrial structural and calcium channel remodeling may occur in streptozotocin-induced type 2 diabetic rats and can be alleviated by rosuvastatin (RSV) therapy. We randomly divided Wistar rats into control, untreated diabetic, RSV-treated control, and RSV-treated diabetic animals. After treatment with RSV for 4 weeks, rats were assessed by metabolic tests, histopathology, and transmission electron microscopy. The expression of Cav1.2, Cav3.1, and Cav3.2 in atrial tissues was detected by real-time reverse transcriptase polymerase chain reaction and Western blot, and inward calcium currents (lCa-L and lCa-T) were recorded in isolated atrial myocytes using patch-clamp techniques. Compared with controls, diabetic rats displayed severe metabolic disorders and a disorganized cellular ultrastructure. In diabetic rats, the expression of Cav1.2 mRNA and protein was significantly decreased, whereas that of Cav3.1 was significantly increased. Long-term RSV treatment partially relieved some pathological changes in diabetic rats. However, Cav3.2 mRNA and protein remained unchanged in control and diabetic groups and was unaffected by RSV. Diabetic atrial myocytes showed significantly reduced L-type but increased T-type, Ca currents, and this effect was significantly reversed by RSV. In conclusion, long-term RSV therapy can alleviate structural and calcium channel remodeling in the type 2 diabetic rat atrium. PMID:26335222

  2. Structure of the minor pseudopilin XcpW from the Pseudomonas aeruginosa type II secretion system

    Energy Technology Data Exchange (ETDEWEB)

    Franz, Laura P.; Douzi, Badreddine; Durand, Eric; Dyer, David H.; Voulhouxd, Romé; Forest, Katrina T. (CNRS-UMR); (CNRS-CRMD); (UW)

    2012-01-13

    Pseudomonas aeruginosa utilizes the type II secretion machinery to transport virulence factors through the outer membrane into the extracellular space. Five proteins in the type II secretion system share sequence homology with pilin subunits of type IV pili and are called the pseudopilins. The major pseudopilin X{sub cp}T{sub G} assembles into an intraperiplasmic pilus and is thought to act in a piston-like manner to push substrates through an outer membrane secretin. The other four minor pseudopilins, X{sub cp}U{sub H}, X{sub cp}V{sub I}, X{sub cp}W{sub J} and X{sub cp}X{sub K}, play less well defined roles in pseudopilus formation. It was recently discovered that these four minor pseudopilins form a quaternary complex that is presumed to initiate the formation of the pseudopilus and to localize to its tip. Here, the structure of X{sub cp}W{sub J} was refined to 1.85 {angstrom} resolution. The structure revealed the type IVa pilin fold with an embellished variable antiparallel {beta}-sheet as also found in the X{sub cp}W{sub J} homologue enterotoxigenic Escherichia coli G{sub sp}J{sub W} and the X{sub cp}U{sub H} homologue Vibrio cholerae E{sub ps}U{sub H}. It is proposed that the exposed surface of this sheet may cradle the long N-terminal 1 helix of another pseudopilin. The final 31 amino acids of the X{sub cp}W{sub J} structure are instrinsically disordered. Deletion of this unstructured region of X{sub cp}W{sub J} did not prevent type II secretion in vivo.

  3. Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein

    International Nuclear Information System (INIS)

    The structure of the Tse3–Tsi3 complex associated with the bacterial type VI secretion system of P. aeruginosa has been solved and refined at 1.9 Å resolution. The structural basis of the recognition of the muramidase effector and its inactivation by its cognate immunity protein is revealed. The type VI secretion system (T6SS) is a bacterial protein-export machine that is capable of delivering virulence effectors between Gram-negative bacteria. The T6SS of Pseudomonas aeruginosa transports two lytic enzymes, Tse1 and Tse3, to degrade cell-wall peptidoglycan in the periplasm of rival bacteria that are competing for niches via amidase and muramidase activities, respectively. Two cognate immunity proteins, Tsi1 and Tsi3, are produced by the bacterium to inactivate the two antibacterial effectors, thereby protecting its siblings from self-intoxication. Recently, Tse1–Tsi1 has been structurally characterized. Here, the structure of the Tse3–Tsi3 complex is reported at 1.9 Å resolution. The results reveal that Tse3 contains a C-terminal catalytic domain that adopts a soluble lytic transglycosylase (SLT) fold in which three calcium-binding sites were surprisingly observed close to the catalytic Glu residue. The electrostatic properties of the substrate-binding groove are also distinctive from those of known structures with a similar fold. All of these features imply that a unique catalytic mechanism is utilized by Tse3 in cleaving glycosidic bonds. Tsi3 comprises a single domain showing a ?-sandwich architecture that is reminiscent of the immunoglobulin fold. Three loops of Tsi3 insert deeply into the groove of Tse3 and completely occlude its active site, which forms the structural basis of Tse3 inactivation. This work is the first crystallographic report describing the three-dimensional structure of the Tse3–Tsi3 effector–immunity pair

  4. Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Tianyu [Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Ding, Jinjing; Zhang, Ying; Wang, Da-Cheng, E-mail: dcwang@ibp.ac.cn [Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Liu, Wei, E-mail: dcwang@ibp.ac.cn [The Third Military Medical University, Chongqing 400038 (China); Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China)

    2013-10-01

    The structure of the Tse3–Tsi3 complex associated with the bacterial type VI secretion system of P. aeruginosa has been solved and refined at 1.9 Å resolution. The structural basis of the recognition of the muramidase effector and its inactivation by its cognate immunity protein is revealed. The type VI secretion system (T6SS) is a bacterial protein-export machine that is capable of delivering virulence effectors between Gram-negative bacteria. The T6SS of Pseudomonas aeruginosa transports two lytic enzymes, Tse1 and Tse3, to degrade cell-wall peptidoglycan in the periplasm of rival bacteria that are competing for niches via amidase and muramidase activities, respectively. Two cognate immunity proteins, Tsi1 and Tsi3, are produced by the bacterium to inactivate the two antibacterial effectors, thereby protecting its siblings from self-intoxication. Recently, Tse1–Tsi1 has been structurally characterized. Here, the structure of the Tse3–Tsi3 complex is reported at 1.9 Å resolution. The results reveal that Tse3 contains a C-terminal catalytic domain that adopts a soluble lytic transglycosylase (SLT) fold in which three calcium-binding sites were surprisingly observed close to the catalytic Glu residue. The electrostatic properties of the substrate-binding groove are also distinctive from those of known structures with a similar fold. All of these features imply that a unique catalytic mechanism is utilized by Tse3 in cleaving glycosidic bonds. Tsi3 comprises a single domain showing a ?-sandwich architecture that is reminiscent of the immunoglobulin fold. Three loops of Tsi3 insert deeply into the groove of Tse3 and completely occlude its active site, which forms the structural basis of Tse3 inactivation. This work is the first crystallographic report describing the three-dimensional structure of the Tse3–Tsi3 effector–immunity pair.

  5. Recent insights into structures and functions of C-type lectins in the immune system

    Science.gov (United States)

    Drickamer, Kurt; Taylor, Maureen E

    2015-01-01

    The majority of the C-type lectin-like domains in the human genome likely to bind sugars have been investigated structurally, although novel mechanisms of sugar binding are still being discovered. In the immune system, adhesion and endocytic receptors that bind endogenous mammalian glycans are often conserved, while pathogen-binding C-type lectins on cells of the innate immune system are more divergent. Lack of orthology between some human and mouse receptors, as well as overlapping specificities of many receptors and formation of receptor hetero-oligomers, can make it difficult to define the roles of individual receptors. There is good evidence that C-type lectins initiate signalling pathways in several different ways, but this function remains the least well understood from a mechanistic perspective. PMID:26163333

  6. Damage identification in beam type structures based on statistical moment using a two step method

    Science.gov (United States)

    Wang, Dansheng; Xiang, Wei; Zhu, Hongping

    2014-02-01

    This paper defines a novel damage index-strain statistical moment, and formulates the fourth strain statistical moment (FSSM) of beam-type structures under white noise excitation. Based on this newly defined strain statistical moment index and the least square optimization algorithm, a two-step damage identification method is proposed. This two-step method is operated like this: first use the difference curves of FSSMs before and after damage to locate damage elements; then for those identified damage elements, employ the model updating method based on the least square algorithm to assess their damage severity. Numerical studies on a simply supported beam and a two-span continuous beam are performed and the study results show that the newly defined index is effective to locate damages, even when the noise intensity is as high as 15 percent. Integrating with the least square-based model updating technique, the damage severities of beam-type structures can also be determined quantitatively. In this way, the proposed two-step method is verified and found to be capable of identifying damage positions and severities of beam-type structures and insensitive to measurement noise.

  7. THE EFFECTS OF SEX, TOPOLOGICAL STRUCTURE, AND TASK TYPE ON HYPERTEXT NAVIGATIONAL PERFORMANCE.

    Science.gov (United States)

    Chang, Wen-Te; Chien, Yu-Hung

    2015-06-01

    Currently, almost all online materials use hyperlinks to provide users access to background, supplemental, or alternative information presented in context, greatly increasing the potential integration of information. However, a major problem is that people do not navigate hyperlinks effectively when the links become more topologically complex. Thus, identification of the variables that lead to navigational errors is necessary for the effective design of hyperlinks. Ninety-one participants (45 women, 46 men) were recruited for this experiment. All were college students and ranged in age from 19 to 23 yr. (M = 20.87, SD = 1.02). Navigational performance was examined in relation to sex, topological structure, and task type. A network topology with single-node task was superior to one with a linear topology under a single-node task condition, but equal to one with a linear topology under a multi-node task condition. Men navigated the linear topology with multi-node task and a network topology with a single-node task significantly faster than women, whereas no significant differences were observed under the other conditions. Sex interacted with topological structure and task type. This study extended the research in this domain by demonstrating an interactive effect among sex, topological structure, and task type on the navigational performance of users and can contribute to research regarding web page design. PMID:26057417

  8. Fine and Superfine Structure of the Decameter-Hectometer Type II Burst on 7 June 2011

    Science.gov (United States)

    Dorovskyy, V. V.; Melnik, V. N.; Konovalenko, A. A.; Brazhenko, A. I.; Panchenko, M.; Poedts, S.; Mykhaylov, V. A.

    2015-07-01

    The characteristics of a type II burst with a herringbone structure observed both with ground-based radio telescopes (UTR-2 and URAN-2) and space-borne spectrometers (STEREO-A and B) are discussed. The burst was recorded on 7 June 2011 in the frequency band 3 - 33 MHz. It was characterized by extremely rich fine structure. Statistical analysis of more than 300 herringbone sub-bursts constituting the burst was performed separately for the positively (reverse) and negatively (forward) drifting sub-bursts. The sense and the degree of circular polarization of the herringbone sub-bursts were measured in a wide frequency band (16 - 32 MHz). A second-order fine frequency structure of the herringbone sub-bursts was observed and studied for the first time. Using STEREO/COR1 and SOHO/LASCO-C2 images, we determined the direction and radial speed of the coronal mass ejection responsible for the studied type II burst. The possible location of the type II burst source on the flank of the shock was found.

  9. Fine and superfine structure of Decameter-Hectometer type II burst on 2011 June 7

    CERN Document Server

    Dorovskyy, V V; Konovalenko, A A; Brazhenko, A I; Panchenko, M; Poedts, S; Mykhaylov, V A

    2015-01-01

    The characteristics of the type II bursts with herringbone structure observed both by ground based radio telescopes (UTR-2, URAN-2) and spaceborn spectrometers (STEREO A-B) are discussed. The burst was recorded on 7 June, 2011 in the frequency band 3--33~MHz. It was characterized by extremely rich fine structure. The statistical analysis of more than 300 herringbone sub-bursts constituting the burst was performed separately for the positively (reverse) and negatively (forward) drifting sub-bursts. The sense and the degree of circular polarization of the herringbone sub-bursts were measured in the respectively wide frequency band (16--32~MHz). A second order fine frequency structure of the herringbone sub-bursts was firstly observed and processed. Using STEREO COR1 (A,B) and SOHO LASCO C2 images the direction and radial speed of the CME responsible for the studied type II burst were determined. The possible location of the type II burst source on the flank of the shock was found.

  10. Study of macroporous silicon electrochemical etching in 3D structured N type silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kouassi, Sebastien; Gautier, Gael; Desplobain, Sebastien; Ventura, Laurent [Laboratoire de Microelectronique de Puissance, Universite Francois Rabelais Tours, 16 Rue Pierre et Marie Curie, 37071 Tours Cedex 2 (France)

    2011-06-15

    In this paper, the electrochemical etching of 3D n-type substrates is investigated. These types of 3D structures are of interest to increase the active surface of some systems. Our aim is to improve a MEMS (Micro-Electro Mechanical System) micro fuel cell power through total surface enhancement without any modification of the cell footprint. To reach this objective, we perform a gas diffusion layer using localized macro-porous silicon. The porous area total surface is improved through trench formation (before porous silicon etching). This is supposed to allow a better power to surface ratio for manufactured fuel cell. The Figure on the right hand side introduces the aimed MEMS based micro fuel cell. The geometrical parameters of the designed structures and the manufacturing process influence are presented. To perform 3D structures, two types of anisotropic etching techniques have been used, alkaline etching of silicon and deep reactive ion etching (DRIE). Additional steps such as a doping layer have been used to improve the results obtained with the initial micro-fabrication process. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. [Soil microbial community structure of two types of forests in the mid-subtropics of China].

    Science.gov (United States)

    Han, Shi-zhong; Gao, Ren; Li, Ai-ping; Ma, Hong-liang; Yin, Yun-feng; Si, You-tao; Chen, Shi-dong; Zheng, Qun-rui

    2015-07-01

    Soil microbial community structures were analyzed by biomarker method of phospholipid fatty acid (PLFA) for a natural forest dominated by Castanopsis fabri (CF) and an adjacent plantation of Cunninghamia lanceolata (CL) in the mid-subtropics of China. The results showed that the amounts of total PLFAs, bacterial PLFAs, fungal PLFAs, gram-positive bacterial PLFAs and gramnegative bacterial PLFAs in the 0-10 cm soil layer were higher than in the 10-20 cm soil layer, and each type of PLFAs in CF were higher than in CL. In either soil layer of the two forest types, the contents of bacterial PLFAs were significantly higher than those of fungal PLFAs. In the two forests, the contents of bacterial PLFAs accounted for 44%-52% of total PLFAs, while the contents of fungal PLFAs just accounted for 6%-8%, indicating the bacteria were dominant in the soils of the two vegetation types. Principal component analysis showed that the influence of vegetation types was greater than soil depth on the microbial community structures. Correlation analysis showed that gram-negative bacterial PLFAs, gram-positive bacterial PLFAs and bacterial PLFAs were significantly negatively correlated with pH, positively with water content, and the PLFAs of main soil microorganism groups were significantly positively correlated with soil total nitrogen, organic carbon, C/N and ammonium. PMID:26710645

  12. Structural analysis for glycolipid recognition by the C-type lectins Mincle and MCL.

    Science.gov (United States)

    Furukawa, Atsushi; Kamishikiryo, Jun; Mori, Daiki; Toyonaga, Kenji; Okabe, Yuki; Toji, Aya; Kanda, Ryo; Miyake, Yasunobu; Ose, Toyoyuki; Yamasaki, Sho; Maenaka, Katsumi

    2013-10-22

    Mincle [macrophage inducible Ca(2+)-dependent (C-type) lectin; CLEC4E] and MCL (macrophage C-type lectin; CLEC4D) are receptors for the cord factor TDM (trehalose-6,6'-dimycolate), a unique glycolipid of mycobacterial cell-surface components, and activate immune cells to confer adjuvant activity. Although it is known that receptor-TDM interactions require both sugar and lipid moieties of TDM, the mechanisms of glycolipid recognition by Mincle and MCL remain unclear. We here report the crystal structures of Mincle, MCL, and the Mincle-citric acid complex. The structures revealed that these receptors are capable of interacting with sugar in a Ca(2+)-dependent manner, as observed in other C-type lectins. However, Mincle and MCL uniquely possess shallow hydrophobic regions found adjacent to their putative sugar binding sites, which reasonably locate for recognition of fatty acid moieties of glycolipids. Functional studies using mutant receptors as well as glycolipid ligands support this deduced binding mode. These results give insight into the molecular mechanism of glycolipid recognition through C-type lectin receptors, which may provide clues to rational design for effective adjuvants. PMID:24101491

  13. Inhibition Kinetics And Emodin Cocrystal Structure of a Type II Polyketide Ketoreductase

    Energy Technology Data Exchange (ETDEWEB)

    Korman, T.P.; Tan, Y.-H.; Wong, J.; Luo, R.; Tsai, S.-C.

    2009-05-20

    Type II polyketides are a class of natural products that include pharmaceutically important aromatic compounds such as the antibiotic tetracycline and antitumor compound doxorubicin. The type II polyketide synthase (PKS) is a complex consisting of 5-10 standalone domains homologous to fatty acid synthase (FAS). Polyketide ketoreductase (KR) provides regio- and stereochemical diversity during the reduction. How the type II polyketide KR specifically reduces only the C9 carbonyl group is not well understood. The cocrystal structures of actinorhodin polyketide ketoreductase (actKR) bound with NADPH or NADP{sup +} and the inhibitor emodin were solved with the wild type and P94L mutant of actKR, revealing the first observation of a bent p-quinone in an enzyme active site. Molecular dynamics simulation help explain the origin of the bent geometry. Extensive screening for in vitro substrates shows that unlike FAS KR, the actKR prefers bicyclic substrates. Inhibition kinetics indicate that actKR follows an ordered Bi Bi mechanism. Together with docking simulations that identified a potential phosphopantetheine binding groove, the structural and functional studies reveal that the C9 specificity is a result of active site geometry and substrate ring constraints. The results lay the foundation for the design of novel aromatic polyketide natural products with different reduction patterns.

  14. Structural and functional analysis of C2-type ketoreductases from modular polyketide synthases.

    Science.gov (United States)

    Zheng, Jianting; Keatinge-Clay, Adrian T

    2011-07-01

    The process by which ?-stereocenters of polyketide intermediates are set by modular polyketide synthases (PKSs) when condensation is not immediately followed by reduction is mysterious. However, the reductase-incompetent ketoreductase (KR) from the third module of 6-deoxyerythronolide B synthase has been proposed to operate as a racemase, aiding in the epimerization process that reverses the orientation of the ?-methyl group of the polyketide intermediate generated by the ketosynthase to the configuration observed in the 6-deoxyerythronolide B final product. To learn more about the epimerization process, the structure of the C2-type KR from the third module of the pikromycin synthase, analogous to the KR from the third module of 6-deoxyerythronolide B synthase, was determined to 1.88 Å resolution. This first structural analysis of this KR-type reveals differences from reductase-competent KRs such as that the site NADPH binds to reductase-competent KRs is occluded by side chains and the putative catalytic tyrosine possesses more degrees of freedom. The active-site geometry may enable C2-type KRs to align the thioester and ?-keto groups of a polyketide intermediate to reduce the pK(a) of the ?-proton and accelerate its abstraction. Results from in vivo assays of engineered PKSs support that C2-type KRs cooperate with epimer-specific ketosynthases to set the configurations of substituent-bearing ?-carbons. PMID:21570406

  15. A new type of intelligent wireless sensing network for health monitoring of large-size structures

    Science.gov (United States)

    Lei, Ying; Liu, Ch.; Wu, D. T.; Tang, Y. L.; Wang, J. X.; Wu, L. J.; Jiang, X. D.

    2009-07-01

    In recent years, some innovative wireless sensing systems have been proposed. However, more exploration and research on wireless sensing systems are required before wireless systems can substitute for the traditional wire-based systems. In this paper, a new type of intelligent wireless sensing network is proposed for the heath monitoring of large-size structures. Hardware design of the new wireless sensing units is first studied. The wireless sensing unit mainly consists of functional modules of: sensing interface, signal conditioning, signal digitization, computational core, wireless communication and battery management. Then, software architecture of the unit is introduced. The sensing network has a two-level cluster-tree architecture with Zigbee communication protocol. Important issues such as power saving and fault tolerance are considered in the designs of the new wireless sensing units and sensing network. Each cluster head in the network is characterized by its computational capabilities that can be used to implement the computational methodologies of structural health monitoring; making the wireless sensing units and sensing network have "intelligent" characteristics. Primary tests on the measurement data collected by the wireless system are performed. The distributed computational capacity of the intelligent sensing network is also demonstrated. It is shown that the new type of intelligent wireless sensing network provides an efficient tool for structural health monitoring of large-size structures.

  16. Observation of Current Structures at Type-III ELM Onset on EAST

    DEFF Research Database (Denmark)

    Yan, Ning; Naulin, Volker

    In far scrape-o layer (SOL), alternating negative and positive burst structures in ion saturation current were detected at the onset of each type-III edge localized mode (ELM) on EAST. Different from the fast streaming phenomenon reported previously, one subsequent positive burst structure appears every time in the early phase of ELM. It seems like a quick transitional stage between edge localized mode (MHD) phase and transport phase during the ELM. A pronounced sinusoidal pattern has been observed on the radial magnetic induction signal by Langmuir - magnetic probe, corresponding with almost a single peak mode on the poloidal induction signal in this transitional phase. As a local diagnostic, the floating potential arises abruptly in this phase, indicating the emergence or passage of polarized plasma structure. Further more, the ELM crash enter into another phase after this sudden burst structure. To verify the current characteristic of this structure, a mono-polar current filaments model was involved, which can reproduce same pattern commendably. Thus, current transport may dominant in transitional stage and plays an important role in the nonlinear development phase of ELM exhaustive crash. As current structure can only be observed in far SOL region of EAST, it maybe conceivable to consider the current origin from local condition rather than release from inside of the pedestal. Our observation may potentially provide support evidence for the recent theory prediction that the error led generated by scrape-off layer current can ultimately trigger the ELM through the coupling with MHD modes inside the separatrix.

  17. Mutational and structural analysis of Japanese patients with mucopolysaccharidosis type II.

    Science.gov (United States)

    Kato, Tomomi; Kato, Zenichiro; Kuratsubo, Izumi; Tanaka, Noboru; Ishigami, Tabito; Kajihara, Jun-Ichi; Sukegawa-Hayasaka, Kazuko; Orii, Koji; Isogai, Koji; Fukao, Toshiyuki; Shimozawa, Nobuyuki; Orii, Tadao; Kondo, Naomi; Suzuki, Yasuyuki

    2005-01-01

    We investigated mutations of the iduronate-2-sulfatase (I2S) gene and structural characteristics of I2S to clarify genotype/phenotype relationships in 18 Japanese patients with mucopolysaccharidosis type II. The I2S gene was analyzed in five patients with a severe phenotype and in 13 patients with an attenuated phenotype. The tertiary structural model of the human I2S was constructed by homology modeling using the arylsulfatase structure as a template. We identified four missense mutations and a nonsense mutation in the severe phenotype; four missense, two nonsense, three frame shifts, and one each of splice and amino acid deletion in the attenuated phenotype. Seven of them (L73del, Q75X, G140R, C171R, V401 fs, C422 fs, and H441 fs) were novel mutations. Structural analysis indicated that the residues of the mutations found in the severe phenotype would have direct interactions with the active site residues or should break the hydrophobic core domain of I2S, whereas residues of the missense mutations found in the attenuated phenotype were located in the peripheral region. In addition, effects by deletion or frameshift mutations could also be interpreted by the structure. Structural analysis of mutant proteins would help in understanding the genotype/phenotype relationships of Hunter disease. PMID:16133661

  18. Sloshing and fluid-structure interaction in a 400-MWe pool-type advanced fast reactor

    International Nuclear Information System (INIS)

    This paper describes the seismic analysis of a 400-MWe advanced fast reactor under 0.3 g SSE ground excitation. Two types of analyses are performed - the sloshing analysis and the fluid-structure interaction analysis. In the sloshing analysis, the sloshing frequency and wave patterns are calculated. The maximum wave height and the sloshing forces exerted on the submerged components and the primary tank are evaluated. In the fluid-structure interaction analysis, the maximum horizontal acceleration for the reactor core and the relative displacement between the reactor core and UIS are examined. The fluid-coupling phenomena between various components are investigated. Seismic stresses at critical areas are examined. The results obtained from this study are very useful to the design of the advanced reactors. Meanwhile, the computer code FLUSTR-ANL has proved to be a useful analytical tool for assessing the complicated seismic fluid-structure interactions and sloshing in the fast reactor systems. 10 refs., 25 figs

  19. Four basic symmetry types in the universal 7-cluster structure of 143 complete bacterial genomic sequences

    CERN Document Server

    Gorban, A N; Zinovyev, A Yu

    2011-01-01

    Coding information is the main source of heterogeneity (non-randomness) in the sequences of bacterial genomes. This information can be naturally modeled by analysing cluster structures in the "in-phase" triplet distributions of relatively short genomic fragments (200-400bp). We found a universal 7-cluster structure in bacterial genomic sequences and explained its properties. We show that codon usage of bacterial genomes is a multi-linear function of their genomic G+C-content with high accuracy. Based on the analysis of 143 completely sequenced bacterial genomes available in Genbank in August 2004, we show that there are four "pure" types of the 7-cluster structure observed. All 143 cluster animated 3D-scatters are collected in a database and is made available on our web-site: http://www.ihes.fr/~zinovyev/7clusters The finding can be readily introduced into any software for gene prediction, sequence alignment or bacterial genomes classification.

  20. Oxide-ion conduction and dielectric relaxations for fluorite type structure

    International Nuclear Information System (INIS)

    The oxide-ion conduction and dielectric properties of 10 mol% CaO stabilized ZrO2 (10CSZ) and 25 mol% Y2O3 stabilized Bi2O3 (25YSB) which are oxide ion conductors having a fluorite-type structure were investigated. The numerical analyses for the frequency dependences of dielectric constants (?r') and dielectric loss factors (?r'') revealed that the dielectric properties were explained by Debye-type polarization due to dopant-vacancy associates and/or electrolyte-electrode interfacial polarization due to charging or loss current. No Debye-type polarization was observed in 25YSB because of no effective charge at the Y3+-doped Bi3+ site. On the other hand, two Debye-type dipoles observed in 10CSZ were assigned to two kinds of associates, [CaZr''-Vo··]·, which was due to dopant-vacancy associates with two different distances between (CaZr'') and (Vo··). The frequency dependence of dielectric loss tangent (tan?) in 25YSB was ascribed to the interface loss due to the charged current, while that of tan? in 8YSZ was ascribed to the Debye-type dipoles in addition to the interface loss.

  1. Data with Hierarchical Structure: Impact of Intraclass Correlation and Sample Size on Type-I Error

    Science.gov (United States)

    Musca, Serban C.; Kamiejski, Rodolphe; Nugier, Armelle; Méot, Alain; Er-Rafiy, Abdelatif; Brauer, Markus

    2011-01-01

    Least squares analyses (e.g., ANOVAs, linear regressions) of hierarchical data leads to Type-I error rates that depart severely from the nominal Type-I error rate assumed. Thus, when least squares methods are used to analyze hierarchical data coming from designs in which some groups are assigned to the treatment condition, and others to the control condition (i.e., the widely used “groups nested under treatment” experimental design), the Type-I error rate is seriously inflated, leading too often to the incorrect rejection of the null hypothesis (i.e., the incorrect conclusion of an effect of the treatment). To highlight the severity of the problem, we present simulations showing how the Type-I error rate is affected under different conditions of intraclass correlation and sample size. For all simulations the Type-I error rate after application of the popular Kish (1965) correction is also considered, and the limitations of this correction technique discussed. We conclude with suggestions on how one should collect and analyze data bearing a hierarchical structure. PMID:21687445

  2. Cybernetic preductoon of AB2Ge2 composition germanides with ThCr2Si2 type crystal structure

    International Nuclear Information System (INIS)

    The prediction of AB2Ge2 composition ternary compounds with a crystalline structure of the ThCr2Si2 type has been accomplished using the training computer. The predicting table fragment containing the greatest number of forcasted phases has been given. General regularities of formation of compounds with the ThCr2Si2 type crystalline structure have been discussed

  3. Thermoelectric properties and micro-structure characteristics of annealed N-type bismuth telluride thin film

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Zhao-kun; Fan, Ping, E-mail: fanping308@126.com; Zheng, Zhuang-hao; Liu, Peng-juan; Chen, Tian-bao; Cai, Xing-min; Luo, Jing-ting; Liang, Guang-xing; Zhang, Dong-ping

    2013-09-01

    N-type bismuth telluride (Bi{sub 2}Te{sub 3}) thermoelectric thin films were deposited by co-sputtering simple substance Te and Bi targets. The deposited films were annealed under various temperatures. The composition ratio, micro-structure and thermoelectric properties of the prepared films were systematically investigated by energy dispersive spectrometer, X-ray diffraction, four-probe method and Seebeck coefficient measurement system. When the annealing temperature is 400 °C, the stoichiometric N-type Bi{sub 2}Te{sub 3} film is achieved, which has a maximum thermoelectric power factor of 0.821 × 10{sup ?3} W m{sup ?1} K{sup ?2}. Furthermore, the dependence of Seebeck coefficient, electrical conductivity and power factor of the stoichiometric N-type Bi{sub 2}Te{sub 3} film annealed at film 400 °C on the applied temperature ranging from 25 °C to 315 °C was investigated. The results show that a highest power factor of 3.288 × 10{sup ?3} W m{sup ?1} K{sup ?2} is obtained at the applied temperature of 275 °C. The structural and thermoelectric properties of the deposited bismuth telluride thin films are greatly improved by annealing and the Seebeck coefficient, electrical conductivity and power factor increase with the applied temperature rising, which are helpful and could be guidance for preparing the high-performance thin film thermoelectric materials for thermoelectric application.

  4. Thermoelectric properties and micro-structure characteristics of annealed N-type bismuth telluride thin film

    International Nuclear Information System (INIS)

    N-type bismuth telluride (Bi2Te3) thermoelectric thin films were deposited by co-sputtering simple substance Te and Bi targets. The deposited films were annealed under various temperatures. The composition ratio, micro-structure and thermoelectric properties of the prepared films were systematically investigated by energy dispersive spectrometer, X-ray diffraction, four-probe method and Seebeck coefficient measurement system. When the annealing temperature is 400 °C, the stoichiometric N-type Bi2Te3 film is achieved, which has a maximum thermoelectric power factor of 0.821 × 10?3 W m?1 K?2. Furthermore, the dependence of Seebeck coefficient, electrical conductivity and power factor of the stoichiometric N-type Bi2Te3 film annealed at film 400 °C on the applied temperature ranging from 25 °C to 315 °C was investigated. The results show that a highest power factor of 3.288 × 10?3 W m?1 K?2 is obtained at the applied temperature of 275 °C. The structural and thermoelectric properties of the deposited bismuth telluride thin films are greatly improved by annealing and the Seebeck coefficient, electrical conductivity and power factor increase with the applied temperature rising, which are helpful and could be guidance for preparing the high-performance thin film thermoelectric materials for thermoelectric application.

  5. Spectral structures and their generation mechanisms for solar radio type-I bursts

    International Nuclear Information System (INIS)

    The fine spectral structures of solar radio type-I bursts were observed by the solar radio telescope AMATERAS. The spectral characteristics, such as the peak flux, duration, and bandwidth, of the individual burst elements were satisfactorily detected by the highly resolved spectral data of AMATERAS with the burst detection algorithm that is improved in this study. The peak flux of the type-I bursts followed a power-law distribution with a spectral index of 2.9-3.3, whereas their duration and bandwidth were distributed more exponentially. There were almost no correlations between the peak flux, duration, and bandwidth. That means there was no similarity in the shapes of the burst spectral structures. We defined the growth rate of a burst as the ratio between its peak flux and duration. There was a strong correlation between the growth rate and peak flux. These results suggest that the free energy of type-I bursts that is originally generated by nonthermal electrons is modulated in the subsequent stages of the generation of nonthermal electrons, such as plasma wave generation, radio wave emissions, and propagation. The variation of the timescale of the growth rate is significantly larger than that of the coronal environments. These results can be explained by the situation wherein the source region may have the inhomogeneity of an ambient plasma environment, such as the boundary of open and closed field lines, and the superposition of entire emitted bursts was observed by the spectrometer.

  6. The electronic structure of zircon-type orthovanadates: Effects of high-pressure and cation substitution

    CERN Document Server

    Panchal, V; Segura, A; Rodriguez-Hernandez, P; Munoz, A; Lopez-Moreno, S; Bettinelli, M; 10.1063/1.3626060

    2012-01-01

    The electronic structure of four ternary-metal oxides containing isolated vanadate ions is studied. Zircon-type YVO4, YbVO4, LuVO4, and NdVO4 are investigated by high-pressure optical-absorption measurements up to 20 GPa. First-principles calculations based on density-functional theory were also performed to analyze the electronic band structure as a function of pressure. The electronic structure near the Fermi level originates largely from molecular orbitals of the vanadate ion, but cation substitution influence these electronic states. The studied ortovanadates, with the exception of NdVO4, undergo a zircon-scheelite structural phase transition that causes a collapse of the band-gap energy. The pressure coefficient dEg/dP show positive values for the zircon phase and negative values for the scheelite phase. NdVO4 undergoes a zircon-monazite-scheelite structural sequence with two associated band-gap collapses.

  7. A Salmonella type three secretion effector/chaperone complex adopts a hexameric ring-like structure.

    Science.gov (United States)

    Roblin, Pierre; Dewitte, Frédérique; Villeret, Vincent; Biondi, Emanuele G; Bompard, Coralie

    2015-02-15

    Many bacterial pathogens use type three secretion systems (T3SS) to inject virulence factors, named effectors, directly into the cytoplasm of target eukaryotic cells. Most of the T3SS components are conserved among plant and animal pathogens, suggesting a common mechanism of recognition and secretion of effectors. However, no common motif has yet been identified for effectors allowing T3SS recognition. In this work, we performed a biochemical and structural characterization of the Salmonella SopB/SigE chaperone/effector complex by small-angle X-ray scattering (SAXS). Our results showed that the SopB/SigE complex is assembled in dynamic homohexameric-ring-shaped structures with an internal tunnel. In this ring, the chaperone maintains a disordered N-terminal end of SopB molecules, in a good position to be reached and processed by the T3SS. This ring dimensionally fits the ring-organized molecules of the injectisome, including ATPase hexameric rings; this organization suggests that this structural feature is important for ATPase recognition by T3SS. Our work constitutes the first evidence of the oligomerization of an effector, analogous to the organization of the secretion machinery, obtained in solution. As effectors share neither sequence nor structural identity, the quaternary oligomeric structure could constitute a strategy evolved to promote the specificity and efficiency of T3SS recognition. PMID:25404693

  8. Three-dimensional structure of recombinant type 1 inositol 1,4,5-trisphosphate receptor

    Science.gov (United States)

    Wolfram, Francis; Morris, Edward; Taylor, Colin W.

    2010-01-01

    IP3Rs (inositol 1,4,5-trisphosphate receptors) are the intracellular channels that mediate release of Ca2+ from the endoplasmic reticulum in response to the many stimuli that evoke Ins(1,4,5)P3 formation. We characterized and purified type 1 IP3R heterologously expressed in Sf9 insect cells, and used the purified IP3R1 to determine its three-dimensional structure by electron microscopy and single-particle analysis. Recombinant IP3R1 has 4-fold symmetry with overall dimensions of approx. 19.5 nm×19.5 nm×17.5 nm. It comprises a small domain, which is likely to include the pore, linked by slender bridges to a large cytoplasmic domain with four petal-like regions. Our structures of recombinant IP3R1 and native cerebellar IP3R have similar appearances and dimensions. The only notable difference is the absence of a central stigma-like domain from the cytoplasmic region of recombinant IP3R1. The first structure of a recombinant IP3R is an important step towards developing three-dimensional structures of IP3R that better contribute to our understanding of the structural basis of IP3R activation. PMID:20377523

  9. Structure and order in CoPt-type nanoalloys: From thin films to supported clusters

    Science.gov (United States)

    Andreazza, Pascal; Pierron-Bohnes, Véronique; Tournus, Florent; Andreazza-Vignolle, Caroline; Dupuis, Véronique

    2015-06-01

    Among nanoalloys, Co-Pt type (CoPt or FePt) supported nanostructures are very interesting systems due to the direct link between atom arrangement and magnetic behavior. In addition, these alloys become model systems in the field of nanoalloys, due to the diversity of atom arrangements either present in the bulk state or specific to the nanoscale (chemically ordered L10, L12, or disordered fcc structures, core-shell, five-fold structures - icosahedral or decahedral, etc.). The synergy between experimental and modeling efforts has allowed the emergence of an overview of the structural, morphological and chemical behaviors of CoPt-based supported nanoparticles in terms of phase diagrams (temperature, composition, size effect), kinetic behavior (growth, annealing, ordering), and also in terms of environment effects (substrate, capping, matrix, gas) and of magnetic properties. All aspects of this complexity are reviewed: synthesis strategies (physical deposition, cluster beam deposition and wet chemical methods), magnetic behavior (atomic magnetic moment, magnetic anisotropy energy), structural transitions (non-crystalline/crystalline structures, order/disorder, surface/interface segregation), etc. In this field, the investigation techniques, such as electron microscopy and X-ray scattering or absorption techniques, are generally used at their ultimate limit due the small size of the studied objects. Finally, several aspects of the annealing process, which is a key phenomenon to achieve the chemical order, have been discussed in both thermodynamic and kinetic points of view (size effect, critical temperature, annealing time, twinning, coalescence, etc.).

  10. Flow structure of water in carbon nanotubes: poiseuille type or plug-like?

    Science.gov (United States)

    Hanasaki, Itsuo; Nakatani, Akihiro

    2006-04-14

    We have conducted molecular dynamics simulations of water flow in carbon nanotubes (CNTs) for (6,6) to (20,20) CNTs at a streaming velocity of 100 ms. The fluidized piston model (FPM) and the ice piston model (IPM) are employed to drive flow through the CNTs. The results show that the single-file water flow inside (6,6) CNT has a convex upward streaming velocity profile, whereas the velocity profiles in (10,10) to (20,20) CNTs are flat except near the tube wall. The flow structure of cylindrical water in the (8,8) CNT is intermediate between that for the (6,6) CNT and the larger CNTs. The flow parameters are found not to exhibit any dependence on streaming velocity at up to 300 ms in the (12,12) CNT. The hydrogen bond lifetimes of water flowing in CNTs tend to be longer than for the corresponding equilibrium states, and nonzero flow does not reduce the microscopic structure or structural robustness (hydrogen bond lifetime). Although the atomic density profile varies with tube diameter, reflecting the change in static microscopic structure of flow from single file to cylindrical, tube diameter does not induce a clear transition in streaming velocity, temperature, or hydrogen bond lifetime over this diameter range. The results suggest that water flow in CNTs of this size is more pluglike than Poiseuille type, although the flow structure does not strictly accord with either definition. PMID:16626232

  11. The Spectra of Type IIB Flux Compactifications at Large Complex Structure

    CERN Document Server

    Brodie, Callum

    2015-01-01

    We compute the spectra of the Hessian matrix, ${\\cal H}$, and the matrix ${\\cal M}$ that governs the critical point equation of the low-energy effective supergravity, as a function of the complex structure and axio-dilaton moduli space in type IIB flux compactifications at large complex structure. We find both spectra analytically in an $h^{1,2}_-+3$ real-dimensional subspace of the moduli space, and show that they exhibit a universal structure with highly degenerate eigenvalues, independently of the choice of flux, the details of the compactification geometry, and the number of complex structure moduli. In this subspace, the spectrum of the Hessian matrix contains no tachyons, but there are also no critical points. We show numerically that the spectra of ${\\cal H}$ and ${\\cal M}$ remain highly peaked over a large fraction of the sampled moduli space of explicit Calabi-Yau compactifications with 2 to 5 complex structure moduli. In these models, the scale of the supersymmetric contribution to the scalar masses...

  12. Structural and bioinformatic characterization of an Acinetobacter baumannii type II carrier protein

    Energy Technology Data Exchange (ETDEWEB)

    Allen, C. Leigh; Gulick, Andrew M., E-mail: gulick@hwi.buffalo.edu [University at Buffalo, Buffalo, NY 14203 (United States)

    2014-06-01

    The high-resolution crystal structure of a free-standing carrier protein from Acinetobacter baumannii that belongs to a larger NRPS-containing operon, encoded by the ABBFA-003406–ABBFA-003399 genes of A. baumannii strain AB307-0294, that has been implicated in A. baumannii motility, quorum sensing and biofilm formation, is presented. Microorganisms produce a variety of natural products via secondary metabolic biosynthetic pathways. Two of these types of synthetic systems, the nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs), use large modular enzymes containing multiple catalytic domains in a single protein. These multidomain enzymes use an integrated carrier protein domain to transport the growing, covalently bound natural product to the neighboring catalytic domains for each step in the synthesis. Interestingly, some PKS and NRPS clusters contain free-standing domains that interact intermolecularly with other proteins. Being expressed outside the architecture of a multi-domain protein, these so-called type II proteins present challenges to understand the precise role they play. Additional structures of individual and multi-domain components of the NRPS enzymes will therefore provide a better understanding of the features that govern the domain interactions in these interesting enzyme systems. The high-resolution crystal structure of a free-standing carrier protein from Acinetobacter baumannii that belongs to a larger NRPS-containing operon, encoded by the ABBFA-003406–ABBFA-003399 genes of A. baumannii strain AB307-0294, that has been implicated in A. baumannii motility, quorum sensing and biofilm formation, is presented here. Comparison with the closest structural homologs of other carrier proteins identifies the requirements for a conserved glycine residue and additional important sequence and structural requirements within the regions that interact with partner proteins.

  13. Structural and bioinformatic characterization of an Acinetobacter baumannii type II carrier protein

    International Nuclear Information System (INIS)

    The high-resolution crystal structure of a free-standing carrier protein from Acinetobacter baumannii that belongs to a larger NRPS-containing operon, encoded by the ABBFA-003406–ABBFA-003399 genes of A. baumannii strain AB307-0294, that has been implicated in A. baumannii motility, quorum sensing and biofilm formation, is presented. Microorganisms produce a variety of natural products via secondary metabolic biosynthetic pathways. Two of these types of synthetic systems, the nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs), use large modular enzymes containing multiple catalytic domains in a single protein. These multidomain enzymes use an integrated carrier protein domain to transport the growing, covalently bound natural product to the neighboring catalytic domains for each step in the synthesis. Interestingly, some PKS and NRPS clusters contain free-standing domains that interact intermolecularly with other proteins. Being expressed outside the architecture of a multi-domain protein, these so-called type II proteins present challenges to understand the precise role they play. Additional structures of individual and multi-domain components of the NRPS enzymes will therefore provide a better understanding of the features that govern the domain interactions in these interesting enzyme systems. The high-resolution crystal structure of a free-standing carrier protein from Acinetobacter baumannii that belongs to a larger NRPS-containing operon, encoded by the ABBFA-003406–ABBFA-003399 genes of A. baumannii strain AB307-0294, that has been implicated in A. baumannii motility, quorum sensing and biofilm formation, is presented here. Comparison with the closest structural homologs of other carrier proteins identifies the requirements for a conserved glycine residue and additional important sequence and structural requirements within the regions that interact with partner proteins

  14. Structural analysis on the open basket type instrumented capsule for fuel irradiation test in HANARO

    International Nuclear Information System (INIS)

    To develop the open basket type instrumented capsule to be used for the irradiation test of various nuclear fuels, it is necessary to ensure the compatibility of a capsule with HANARO and the structural integrity of a capsule. The dimensions of open basket type instrumented capsule was determined in the basis of the pressure drop criterion in OR test hole of HANARO(mass flow rate m200kPa). From the buckling stability analysis for this capsule, the critical buckling load Pcr was 7.5kN. The vertical impact stress of the capsule under unit impact load was examined by the transient analysis, and the maximum vertical impact load calculated from the impact stress and the allowable stress was 65.3kN. And under the loading Pcr calculated from the analysis of buckling of capsule, the maximum vertical impact stress was 20.4MPa. The structural integrity of a capsule under horizontal impact loading was also examined. The mechanical stresses occurred by a pressure difference at the inner and outer surface of cladding and by a coolant pressure at the surface of cladding were 2.32MPa and 40.55MPa, respectively. Theses stress values were lower than the allowable stress in each case. Therefore, it was ensured that the instrumented capsule for the irradiation test of various nuclear fuels meets the criteria on the structural integrity during installing, and testing the capsule in HANARO

  15. From Proteomics to Structural Studies of Cytosolic/Mitochondrial-Type Thioredoxin Systems in Barley Seeds

    DEFF Research Database (Denmark)

    Shahpiri, Azar; Svensson, Birte

    2009-01-01

    Thioredoxins (Trx) are ubiquitous proteins that participate in thiol disulfide reactions via two active site cysteine residues, allowing Trx to reduce disulfide bonds in target proteins. Recent progress in proteome analysis has resulted in identification of a wide range of potential target proteins for Trx, indicating that Trx plays a key role in several aspects of cell metabolism. In contrast to other organisms, plants contain multiple forms of Trx that are classified based on their primary structures and sub-cellular localization. The reduction of cytosolic and mitochondrial types of Trx is dependent on NADPH and catalyzed by NADPH-dependent thioredoxin reductase (NTR). In barley, two isoforms each of Trx and NTR have been identified and investigated using proteomics, gene expression, and structural studies. This review outlines the diverse roles suggested for cytosolic/mitochondrial-type Trx systems in cereal seeds and summarizes the current knowledge of the barley system including recent data on function,regulation, interactions, and structure. Directions for future research are discussed.

  16. A study on structural changes in protein by time-division type Laue method

    International Nuclear Information System (INIS)

    In order to know the physiological roles of proteins, it is important to investigate the intermediate states of their structural changes. The sizes of proteins are generally several tens angstrom(A). Considering the resolution, only x-ray crystal analysis can be used in practice for the investigation of the mechanism of protein structural changes, though NMR is applicable only for small-sized proteins. However, x-ray analysis is not so suitable for analysis of their intermediate states. Thus, the author paid attention to the time-division type Laue method for the study of hemoglobin (Hb). Laser-flash induces to release carbonmonooxide (CO) from carboxyhemoglobin (Hb(CO)4). Therefore, if an appropriate length of x-ray pulse (?100 picosec) is available, the processes in the period from cleavage of the bond between a ligand (O2, CO or NO) and Hb to recombination of them might be monitored. Using DNA recombination and chemical modification techniques, recombinant Hb, of which T structure is stable was produced. An investigation on the conditions which allow to release CO from the Hb is undertaken using a single crystal of this Hb. The experimental systems applicable to time-division type Laue method are some protein molecules participating in chemical reactions inducible by light absorption, the electron-transfer system excited by light and so on. (M.N.)

  17. Crystal structure of a novel cysteinless plant Kunitz-type protease inhibitor

    International Nuclear Information System (INIS)

    Bauhinia bauhinioides Cruzipain Inhibitor (BbCI) is a cysteine protease inhibitor highly homologous to plant Kunitz-type inhibitors. However, in contrast to classical Kunitz family inhibitors it lacks cysteine residues and therefore disulfide bridges. BbCI is also distinct in the ability to inactivate enzymes belonging to two different classes, cysteine and serine proteases. Besides inhibiting the cysteine protease cruzipain, BbCI also inhibits cathepsin L and the serine proteases HNE (human neutrophil elastase) and PPE (porcine pancreatic elastase). Monoclinic crystals of the recombinant inhibitor that diffract to 1.7 A resolution were obtained using hanging drop method by vapor diffusion at 18 oC. The refined structure shows the conservative ?-trefoil fold features of the Kunitz inhibitors. In BbCI, one of the two characteristic S-S bonds is replaced by the water-mediated interaction between Tyr125 and Gly132. In this work we explore the structural differences between Kunitz-type inhibitors and analyze the essential interactions that maintain the protein structural stability preserving its biological function

  18. The centers of early-type galaxies with HST; 2, empirical models and structural parameters

    CERN Document Server

    Byun, Y I; Faber, S M; Ajhar, E A; Dressler, A; Kormendy, J; Lauer, T R; Richstone, D O; Tremaine, S

    1996-01-01

    We present a set of structural parameters for the central parts of 57 early-type galaxies observed with the Planetary Camera of the Hubble Space Telescope. These parameters are based on a new empirical law that successfully characterizes the centers of early type galaxies. This empirical law assumes that the surface brightness profile is a combination of two power laws with different slopes gamma and beta for the inner and outer regions. Conventional structural parameters such as core radius and central surface brightness are replaced by break radius r_b, where the transition between power-law slopes takes place, and surface brightness mu_b at that radius. An additional parameter alpha describes the sharpness of the break. The structural parameters are derived using a chi-squared minimization process applied to the mean surface brightness profiles. The resulting model profiles generally give very good agreement to the observed profiles out to the radius of 10 arcseconds imaged by the Planetary Camera. Excepti...

  19. Fluid Flow through Porous Sandstone with Overprinting and Intersecting Geological Structures of Various Types

    Science.gov (United States)

    Zhou, X.; Karimi-Fard, M.; Durlofsky, L.; Aydin, A.

    2010-12-01

    Impact of a wide variety of structural heterogeneities on fluid flow in an aeolian sandstone in the Valley of Fire State Park (NV), such as (1) dilatant fractures (joints), (2) shear fractures (faults), and (3) contraction/compaction structures (compaction bands), are considered. Each type of these structures has its own geometry, spacing, distribution, connectivity, and hydraulic properties, which either enhance or impede subsurface fluid flow. Permeability of these structures may, on average, be a few orders of magnitude higher or lower than those of the corresponding matrix rocks. In recent years, the influence of a single type of these heterogeneities on fluid flow has been studied individually, such as joints, compaction bands or faults. However, as different types of geological structures are commonly present together in the same rock volume, their combined effect requires a more detailed assessment. In this study, fluid flow simulations are performed using a special finite-volume discretization technique that was developed by Karimi-Fard et al. (2004; 2006). Using this approach, thin features such as fractures and compaction bands are represented as linear elements in unstructured 2D models and as planar elements in 3D models, which significantly reduces the total number of cells and simplifies grid generation. The cell geometric information and the cell-to-cell transmissibility obtained from this discretization technique are input to Stanford’s General Purpose Research Simulator (GPRS) for fluid flow simulation. To account for the effects of the various geological structures on subsurface flow, we perform permeability upscaling over regions corresponding to large-scale simulation grid blocks in order to obtain equivalent permeability components in two principal directions. We will focus on the following problems: (1) compaction bands of multisets; (2) compartmentalization of compaction bands of high-angle, low-angle and horizontal; (3) joints overprinting and intersecting earlier compaction and shear bands at various angles; (4) faults with various sizes overprinting and intersecting earlier compaction and shear bands. The preliminary results are: (1) Sets of compaction bands in various orientations are capable of compartmentalizing the rock volume. (2) If one set of joints are parallel to one set of compaction bands, the combined effect to the upscaled permeability is not significant. (3) If a joint set intersects a set of compaction bands, the combined effect counter acts the impeding of fluid flow by the compaction bands at high-angle to the bands. On the other hand the effect on the upscaled permeability in the direction of the bands is not significant. The effects of the combination of faults and compaction bands on fluid flow in various directions are complex and being evaluated.

  20. Structural Biology Insight for the Design of Sub-type Selective Aurora Kinase Inhibitors.

    Science.gov (United States)

    Sarvagalla, Sailu; Coumar, Mohane Selvaraj

    2015-01-01

    Aurora kinase A, B and C, are key regulators of mitosis and are over expressed in many of the human cancers, making them an ideal drug target for cancer chemotherapy. Currently, over a dozen of Aurora kinase inhibitors are in various phases of clinical development. The majority of the inhibitors (VX-680/MK-0457, PHA-739358, CYC116, SNS-314, AMG 900, AT-9283, SCH- 1473759, ABT-348, PF-03814735, R-763/AS-703569, KW-2449 and TAK-901) are pan-selective (isoform non-selective) and few are Aurora A (MLN8054, MLN8237, VX-689/MK5108 and ENMD 2076) and Aurora B (AZD1152 and GSK1070916) sub-type selective. Despite the intensive research efforts in the past decade, no Aurora kinase inhibitor has reached the market. Recent evidence suggests that the sub-type selective Aurora kinase A inhibitor could possess advantages over pan-selective Aurora inhibitors, by avoiding Aurora B mediated neutropenia. However, sub-type selective Aurora kinase A inhibitor design is very challenging due to the similarity in the active site among the isoforms. Structural biology and computational aspects pertaining to the design of Aurora kinase inhibitors were analyzed and found that a possible means to develop sub-type selective inhibitor is by targeting Aurora A specific residues (Leu215, Thr217 and Arg220) or Aurora B specific residues (Arg159, Glu161 and Lys164), near the solvent exposed region of the protein. Particularly, a useful strategy for the design of sub-type selective Aurora A inhibitor could be by targeting Thr217 residue as in the case of MLN8054. Further preclinical and clinical studies with the sub-type selective Aurora inhibitors could help bring them to the market for the treatment of cancer. PMID:25895501

  1. Direct metal micropatterning on needle-type structures towards bioimpedance and chemical sensing applications

    Science.gov (United States)

    Kim, Sanghyeok; Park, Jae-ho; Kang, Kyungnam; Park, Chong-Ook; Park, Inkyu

    2015-01-01

    Direct metal patterning methods, such as screen printing, inkjet printing and gravure/flexography printing, are widely used to form electrodes or interconnections for printed electronic devices due to their inexpensive, simple and rapid fabrication as compared to vacuum-based conventional metallization processes. Here, we present direct metal patterning by modified screen printing on the curved surface of needle-type rod structures (i.e. rods with radius of ? electrochemical impedance spectroscopy of electrolyte solutions and solid objects by the rod insertion. Furthermore, needles with multiple pairs of microelectrodes were used to measure the electrical impedance of biological samples such as fat and muscle tissues of porcine meat. In addition, a needle-type probe sensor with gas sensing capability was demonstrated by using a needle with printed Ag electrodes and Pd thin films.

  2. The effectiveness of structured personal care of type 2 diabetes on recurrent outcomes

    DEFF Research Database (Denmark)

    Lundström, Hanna Maria; Siersma, Volkert Dirk; Nielsen, Anni Brit Sternhagen; Brodersen, John; Reventlow, Susanne; Andersen, Per Kragh; Olivarius, Niels

    2014-01-01

    Abstract AIMS/HYPOTHESIS: The estimation of effect size in clinical trials commonly disregards recurrent outcomes. We investigated the effectiveness of a complex intervention on recurrent outcomes in patients with type 2 diabetes. METHODS: In the Diabetes Care in General Practice (DCGP) randomised...... controlled trial, 1,381 patients newly diagnosed with type 2 diabetes were randomised to 6 years of structured personal care or routine care (ClinicalTrials.gov NCT01074762). The trial had 19 years of registry-based follow-up and was analysed with Cox regression models. Repeated occurrences in the same...... patient of outcomes (any diabetes-related endpoint, myocardial infarction [MI], stroke, peripheral vascular disease and microvascular disease) were accounted for with the Wei, Lin and Weissfeld method. RESULTS: As previously shown, the intervention reduced the rates of first occurrence of both MI and any...

  3. Mechanical adaptability of the Bouligand-type structure in natural dermal armour

    Science.gov (United States)

    Zimmermann, Elizabeth A.; Gludovatz, Bernd; Schaible, Eric; Dave, Neil K. N.; Yang, Wen; Meyers, Marc A.; Ritchie, Robert O.

    2013-10-01

    Arapaima gigas, a fresh water fish found in the Amazon Basin, resist predation by piranhas through the strength and toughness of their scales, which act as natural dermal armour. Arapaima scales consist of a hard, mineralized outer shell surrounding a more ductile core. This core region is composed of aligned mineralized collagen fibrils arranged in distinct lamellae. Here we show how the Bouligand-type (twisted plywood) arrangement of collagen fibril lamellae has a key role in developing their unique protective properties, by using in situ synchrotron small-angle X-ray scattering during mechanical tensile tests to observe deformation mechanisms in the fibrils. Specifically, the Bouligand-type structure allows the lamellae to reorient in response to the loading environment; remarkably, most lamellae reorient towards the tensile axis and deform in tension through stretching/sliding mechanisms, whereas other lamellae sympathetically rotate away from the tensile axis and compress, thereby enhancing the scale’s ductility and toughness to prevent fracture.

  4. Function and Evolutionary Origin of Unicellular Camera-Type Eye Structure

    KAUST Repository

    Hayakawa, Shiho

    2015-03-03

    The ocelloid is an extraordinary eyespot organelle found only in the dinoflagellate family Warnowiaceae. It contains retina- and lens-like structures called the retinal body and the hyalosome. The ocelloid has been an evolutionary enigma because of its remarkable resemblance to the multicellular camera-type eye. To determine if the ocelloid is functionally photoreceptive, we investigated the warnowiid dinoflagellate Erythropsidinium. Here, we show that the morphology of the retinal body changed depending on different illumination conditions and the hyalosome manifests the refractile nature. Identifying a rhodopsin gene fragment in Erythropsidinium ESTs that is expressed in the retinal body by in situ hybridization, we also show that ocelloids are actually light sensitive photoreceptors. The rhodopsin gene identified is most closely related to bacterial rhodopsins. Taken together, we suggest that the ocelloid is an intracellular camera-type eye, which might be originated from endosymbiotic origin. © 2015 Hayakawa et al.

  5. Structural and magnetic Properties of TbZn-substituted calcium barium M-type nano-structured hexa-ferrites

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Hasan M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Department of Electronics, University of York, York YO10 5DD (United Kingdom); Islam, M.U., E-mail: dr.misbahulislam@bzu.edu.pk [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Xu, Yongbing [Department of Electronics, University of York, York YO10 5DD (United Kingdom); Nanjing–York International Centre of Spintronics and Nano-Engineering, Nanjing University, Nanjing 210093 (China); Asif Iqbal, M. [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); National University of Science and Technology, College of E and ME, Islamabad (Pakistan); Ali, Irshad [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan)

    2014-03-15

    Highlights: • Tb–Zn substituted Ca{sub 0.5}Ba{sub 0.5}Fe{sub 12}O{sub 19} samples exhibit single magnetoplumbite phase. • Lattice parameters a and c have increasing values. • Coercivity can be tuned at lower substitution level • Crystallites size was found in the range 18–25 nm by TEM and by Scherrer formula. • These hexa-ferrites are suitable for microwave devices and magnetic recording media. -- Abstract: Effect of TbZn substitution on the structural and magnetic properties of Ca{sub 0.5}Ba{sub 0.5?x}Tb{sub x}Zn{sub y}Fe{sub 12?y}O{sub 19}, (x = 0.00–0.10; y = 0.00–1.00) ferrites prepared by sol–gel auto combustion is reported. The synthesized samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Vibrating Sample magnetometery. The X-ray diffraction analysis confirmed single phase M-type hexa-ferrite structure. The lattice parameters were found to increase as TbZn contents increases, which is attributed to the ionic sizes of the implicated cations. The TbZn seems to be completely soluble in the lattice. The results of scanning electron microscopy and transmission electron microscopy shows that the grain size decreases with increase of TbZn substitution. The coercivity values (1277–2025 Oe) of all samples lies in the range of M-type hexa-ferrite and indicate that an increase of anisotropy was achieved by substitution of TbZn, while the size of nanoparticles was drastically reduced between 18 and 25 nm. The increased anisotropy and fine particle size are useful for many applications, such as improving signal noise ratio of recording devices.

  6. Comparative study on the effects of type 1 and type 2 diabetes on structural changes and hormonal output of the adrenal cortex in male Wistar rats

    Directory of Open Access Journals (Sweden)

    Elahi-Moghaddam Zohreh

    2013-01-01

    Full Text Available Abstract Introduction Diabetes is one of the most common endocrine disorders characterized by hyperglycemia due to defects in insulin secretion, insulin function, or both. Causing dysfunction in the body general metabolism, diabetes-induced chronic hyperglycemia leads to alterations in those endocrine glands involved in regulating the body metabolism. In this line, the present study has been conducted to investigate the effects of type 1 and type 2 diabetes on the structural changes and hormonal output of the adrenal cortex in male Wistar rat. Methods Eighteen male Wistar rats were divided into three groups including control, experimental type 1 diabetes (subcutaneous injection of 135 mg/kg alloxan and experimental type 2 diabetes (8 weeks treatment with drinking water containing 10% fructose. Two months after the induction of both types of diabetes, the level of blood biochemical factors (glucose, insulin, cortisol, triglycerides, cholesterol, LDL, and HDL were measured. Structural changes of the adrenal cortex were then evaluated, using stereological techniques. Results Serum biochemical analysis showed significant difference in the levels of glucose, triglycerides, insulin and cortisol in experimental groups, compared to the control. The results of structural alterations were also indicative of increase in adrenal cortex volume in both types of diabetes. Conclusion Probably through increasing HPA axis activity, type1 diabetes-induced hyperglycemia leads to adrenal hypertrophy and increase the hormonal output of adrenal gland.

  7. Structural Basis for Type VI Secretion Effector Recognition by a Cognate Immunity Protein

    Science.gov (United States)

    Li, Mo; Le Trong, Isolde; Carl, Mike A.; Larson, Eric T.; Chou, Seemay; De Leon, Justin A.; Dove, Simon L.; Stenkamp, Ronald E.; Mougous, Joseph D.

    2012-01-01

    The type VI secretion system (T6SS) has emerged as an important mediator of interbacterial interactions. A T6SS from Pseudomonas aeruginosa targets at least three effector proteins, type VI secretion exported 1–3 (Tse1–3), to recipient Gram-negative cells. The Tse2 protein is a cytoplasmic effector that acts as a potent inhibitor of target cell proliferation, thus providing a pronounced fitness advantage for P. aeruginosa donor cells. P. aeruginosa utilizes a dedicated immunity protein, type VI secretion immunity 2 (Tsi2), to protect against endogenous and intercellularly-transferred Tse2. Here we show that Tse2 delivered by the T6SS efficiently induces quiescence, not death, within recipient cells. We demonstrate that despite direct interaction of Tsi2 and Tse2 in the cytoplasm, Tsi2 is dispensable for targeting the toxin to the secretory apparatus. To gain insights into the molecular basis of Tse2 immunity, we solved the 1.00 Å X-ray crystal structure of Tsi2. The structure shows that Tsi2 assembles as a dimer that does not resemble previously characterized immunity or antitoxin proteins. A genetic screen for Tsi2 mutants deficient in Tse2 interaction revealed an acidic patch distal to the Tsi2 homodimer interface that mediates toxin interaction and immunity. Consistent with this finding, we observed that destabilization of the Tsi2 dimer does not impact Tse2 interaction. The molecular insights into Tsi2 structure and function garnered from this study shed light on the mechanisms of T6 effector secretion, and indicate that the Tse2–Tsi2 effector–immunity pair has features distinguishing it from previously characterized toxin–immunity and toxin–antitoxin systems. PMID:22511866

  8. On the flat spacetime Galileons and the Born-Infeld type structures

    Science.gov (United States)

    Campuzano, Cuauhtemoc; Cordero, Rubén; Cruz, Miguel; Rojas, Efraín

    2015-04-01

    We show how the flat spacetime Galileon field theories (FSGFT) in arbitrary dimensions can be obtained through a Born-Infeld (BI) type structure. This construction involves a brane metric and nonlinear combinations of derivatives of a scalar field. Our setup gives rise to some Galileon tensors and vectors useful for the variational analysis which are related to the momentum density of the probe Lovelock branes floating in a N-dimensional flat bulk. We find further that the Noether currents associated to these Galileon theories may be written in terms of such tensors.

  9. Impact of model structure and parameterization on Penman-Monteith type evaporation models

    Science.gov (United States)

    Ershadi, A.; McCabe, M. F.; Evans, J. P.; Wood, E. F.

    2015-06-01

    The impact of model structure and parameterization on the estimation of evaporation is investigated across a range of Penman-Monteith type models. To examine the role of model structure on flux retrievals, three different retrieval schemes are compared. The schemes include a traditional single-source Penman-Monteith model (Monteith, 1965), a two-layer model based on Shuttleworth and Wallace (1985) and a three-source model based on Mu et al. (2011). To assess the impact of parameterization choice on model performance, a number of commonly used formulations for aerodynamic and surface resistances were substituted into the different formulations. Model response to these changes was evaluated against data from twenty globally distributed FLUXNET towers, representing a cross-section of biomes that include grassland, cropland, shrubland, evergreen needleleaf forest and deciduous broadleaf forest. Scenarios based on 14 different combinations of model structure and parameterization were ranked based on their mean value of Nash-Sutcliffe Efficiency. Results illustrated considerable variability in model performance both within and between biome types. Indeed, no single model consistently outperformed any other when considered across all biomes. For instance, in grassland and shrubland sites, the single-source Penman-Monteith model performed the best. In croplands it was the three-source Mu model, while for evergreen needleleaf and deciduous broadleaf forests, the Shuttleworth-Wallace model rated highest. Interestingly, these top ranked scenarios all shared the simple lookup-table based surface resistance parameterization of Mu et al. (2011), while a more complex Jarvis multiplicative method for surface resistance produced lower ranked simulations. The highly ranked scenarios mostly employed a version of the Thom (1975) formulation for aerodynamic resistance that incorporated dynamic values of roughness parameters. This was true for all cases except over deciduous broadleaf sites, where the simpler aerodynamic resistance approach of Mu et al. (2011) showed improved performance. Overall, the results illustrate the sensitivity of Penman-Monteith type models to model structure, parameterization choice and biome type. A particular challenge in flux estimation relates to developing robust and broadly applicable model formulations. With many choices available for use, providing guidance on the most appropriate scheme to employ is required to advance approaches for routine global scale flux estimates, undertake hydrometeorological assessments or develop hydrological forecasting tools, among many other applications. In such cases, a multi-model ensemble or biome-specific tiled evaporation product may be an appropriate solution, given the inherent variability in model and parameterization choice that is observed within single product estimates.

  10. Structural basis of asymmetry in the human immunodeficiency virus type 1 reverse transcriptase heterodimer.

    OpenAIRE

    Wang, J.; Smerdon, S J; Jäger, J; Kohlstaedt, L. A.; Rice, P A; Friedman, J.M.; T. A. Steitz

    1994-01-01

    The reverse transcriptase from human immunodeficiency virus type 1 is a heterodimer consisting of one 66-kDa and one 51-kDa subunit. The p66 subunit contains both a polymerase and an RNase H domain; proteolytic cleavage of p66 removes the RNase H domain to yield the p51 subunit. Although the polymerase domain of p66 folds into an open, extended structure containing a large active-site cleft, that of p51 is closed and compact. The connection subdomain, which lies between the polymerase and RNa...

  11. Impact of model structure and parameterization on Penman-Monteith type evaporation models

    KAUST Repository

    Ershadi, A.

    2015-04-12

    The impact of model structure and parameterization on the estimation of evaporation is investigated across a range of Penman-Monteith type models. To examine the role of model structure on flux retrievals, three different retrieval schemes are compared. The schemes include a traditional single-source Penman-Monteith model (Monteith, 1965), a two-layer model based on Shuttleworth and Wallace (1985) and a three-source model based on Mu et al. (2011). To assess the impact of parameterization choice on model performance, a number of commonly used formulations for aerodynamic and surface resistances were substituted into the different formulations. Model response to these changes was evaluated against data from twenty globally distributed FLUXNET towers, representing a cross-section of biomes that include grassland, cropland, shrubland, evergreen needleleaf forest and deciduous broadleaf forest. Scenarios based on 14 different combinations of model structure and parameterization were ranked based on their mean value of Nash-Sutcliffe Efficiency. Results illustrated considerable variability in model performance both within and between biome types. Indeed, no single model consistently outperformed any other when considered across all biomes. For instance, in grassland and shrubland sites, the single-source Penman-Monteith model performed the best. In croplands it was the three-source Mu model, while for evergreen needleleaf and deciduous broadleaf forests, the Shuttleworth-Wallace model rated highest. Interestingly, these top ranked scenarios all shared the simple lookup-table based surface resistance parameterization of Mu et al. (2011), while a more complex Jarvis multiplicative method for surface resistance produced lower ranked simulations. The highly ranked scenarios mostly employed a version of the Thom (1975) formulation for aerodynamic resistance that incorporated dynamic values of roughness parameters. This was true for all cases except over deciduous broadleaf sites, where the simpler aerodynamic resistance approach of Mu et al. (2011) showed improved performance. Overall, the results illustrate the sensitivity of Penman-Monteith type models to model structure, parameterization choice and biome type. A particular challenge in flux estimation relates to developing robust and broadly applicable model formulations. With many choices available for use, providing guidance on the most appropriate scheme to employ is required to advance approaches for routine global scale flux estimates, undertake hydrometeorological assessments or develop hydrological forecasting tools, amongst many other applications. In such cases, a multi-model ensemble or biome-specific tiled evaporation product may be an appropriate solution, given the inherent variability in model and parameterization choice that is observed within single product estimates.

  12. Hamiltonian structures and integrability for a discrete coupled KdV-type equation hierarchy

    International Nuclear Information System (INIS)

    Coupled Korteweg-de Vries (KdV) systems have many important physical applications. By considering a 4 × 4 spectral problem, we derive a discrete coupled KdV-type equation hierarchy. Our hierarchy includes the coupled Volterra system proposed by Lou et al. (e-print arXiv: 0711.0420) as the first member which is a discrete version of the coupled KdV equation. We also investigate the integrability in the Liouville sense and the multi-Hamiltonian structures for the obtained hierarchy. (authors)

  13. Long-wavelength infrared detection in a Kastalsky-type superlattice structure

    Science.gov (United States)

    Byungsung, O.; Choe, J.-W.; Francombe, M. H.; Bandara, K. M. S. V.; Coon, D. D.

    1990-01-01

    The first successful demonstration of long-wavelength infrared (LWIR) detection with a Kastalsky-type AlGaAs/GaAs superlattice structure is reported. The experimental response band of the detector is centered near 10 microns in very good agreement with the theoretical response band provided that electron-electron interactions are taken into account. The detector operates at significantly lower bias voltage than photoconductive multiple quantum well LWIR detectors. This could lead to important advantages in applications to photovoltaic detector arrays. The response at 83 K is about 50 percent of the response at 24 K.

  14. Thermal expansion behaviour of sodium zirconium phosphate structure type phosphates containing tin

    International Nuclear Information System (INIS)

    Thermal expansion behaviour of sodium zirconium phosphate structure type phosphates of the formula AM3+SnP3O12 (A=Ca, Sr and Ba; M3+=Cr and Fe) was studied by high temperature X-ray diffraction and dilatometry in the temperature range 298-1073 K. The variation in the hexagonal lattice parameters of the Ca-containing compounds is in line with the 'sodium zirconium phosphate behaviour'. However, the strontium- and barium-containing compounds display an altogether different behaviour of axial expansion. The results are explained based on the crystal chemistry of these compounds

  15. Structure design and optimization of a new type of subsea pipeline connector

    Science.gov (United States)

    Hu, Xiaoming; Wang, Liquan; Liu, Yong; Ge, Rubo; Tan, Lei; Fu, Chuangye; Wei, Zongliang

    2012-03-01

    The basic configuration of a new type of subsea pipeline connector was proposed based on the press-fitting principle, and a parametric finite element model was created using APDL language in ANSYS. Combining the finite element model and optimization technology, the dimension optimization aiming at obtaining the minimum loading force and the optimum sealing performance was designed by the zero order optimization method. Experiments of the optimized connector were carried out. The results indicate that the optimum structural design significantly improved the indicators of the minimum loading force and sealing performance of the connector.

  16. DG-FEM solution for nonlinear wave-structure interaction using Boussinesq-type equations

    DEFF Research Database (Denmark)

    Engsig-Karup, Allan Peter; Hesthaven, Jan; Bingham, Harry B.; Warburton, T.

    2008-01-01

    We present a high-order nodal Discontinuous Galerkin Finite Element Method (DG-FEM) solution based on a set of highly accurate Boussinesq-type equations for solving general water-wave problems in complex geometries. A nodal DG-FEM is used for the spatial discretization to solve the Boussinesq...... equations in complex and curvilinear geometries which amends the application range of previous numerical models that have been based on structured Cartesian grids. The Boussinesq method provides the basis for the accurate description of fully nonlinear and dispersive water waves in both shallow and deep...

  17. COMPARATIVE STRUCTURAL AND FUNCTIONAL ANALYSIS OF E6 ONCOGENE OF HUMAN PAPILLOMAVIRUS TYPE 16

    Directory of Open Access Journals (Sweden)

    Dharmendra Kumar Chaudhary

    2012-12-01

    Full Text Available Human papillomavirus (HPV is an etiologic agent of the uterine cervix cancer and several other neoplasias in women globally. E6 protein of HPV type 16 is highly conserved and plays the key role in an inducing cancer via suppressing activity of P53. We have used different bioinformatics tools for generation of phylogenetic tree, modeling of RNA secondary structure, gene designing and codon optimization of HPV E6 gene. The size of E6 gene sequences of nine strains HPV type 16 was estimated to be 456 to 477 bp and G+C content was ranged between 37.06 to 37.94%. We used E6 gene sequences for construction of phylogenetic relationship and these divided into five groups. RNA secondary structures of E6 gene were modeled and analyzed that folding free energy of wild genes was -093.96, -106.21,-040.48, -090.76, - 072.68, -092.86, -039.32, -044.78, -047.88 kcal/mol and after codon optimization free energy was -122.70, -107.40, - 104.80, -121.40, -127.40, -110.80, -105.20, -122.30, -110.40 kcal/mol respectively. Moreover, gene designing and codon optimization have used to improve the heterologous expression in living organisms by increasing translational efficiency. All strains of HPV16 were used for codon optimization in E. coli. Codon adaptation index (CAI and G+C contents of E6 gene in optimized DNA were enhanced by 3.6 (72.7% and 1.3 (25.2% fold, respectively. The present study provides useful insights into phylogenetic and evolution in the cervical cancer causing Human papillomavirus type 16. The optimized DNA can be chemically synthesized and over expressed in E. coli as compare to its wild type counterparts. Alternatively, the secondary structure and free energy of E6 were investigated that will be helpful to predict the evolution of primitive and genetically stable HPV type 16 strains. This finding provides new insight in better understanding of cervical cancer.

  18. Heterotic and type II orientifold compactifications on SU(3) structure manifolds

    International Nuclear Information System (INIS)

    We study the four-dimensional N=1 effective theories of generic SU(3) structure compactifications in the presence of background fluxes. For heterotic and type IIA/B orientifold theories, the N=1 characteristic data are determined by a Kaluza-Klein reduction of the fermionic actions. The Kaehler potentials, superpotentials and the D-terms are entirely encoded by geometrical data of the internal manifold. The background flux and the intrinsic torsion of the SU(3) structure manifold, gives rise to contributions to the four-dimensional F-terms. The corresponding superpotentials generalize the Gukov-Vafa-Witten superpotential. For the heterotic compactification, the four-dimensional fermionic supersymmetry variations, as well as the conditions on supersymmetric vacua, are determined. The Yukawa couplings of the theory turn out to be similar to their Calabi-Yau counterparts. (Orig.)

  19. Creep deformation and rupture behavior of type 304/308 stainless steel structural weldments

    International Nuclear Information System (INIS)

    The creep deformation and rupture of type 304/308 stainless steel structural weldments at 5930C (11000F) was experimentally investigated to study the comparative behavior of the base metal and weld metal constituents. The tests were conducted in support of ORNL's program to develop high-temperature structural design methods applicable to liquid-metal fast breeder reactor (LMFBR) system components that operate in the creep range. The specimens used were thin-walled, right circular cylinders capped with either flat or hemispherical heads and tested under internal gas pressure. Circumferential welds were located in different regions of the cylinder or head and, with one exception, were geometrically duplicated by all base metal regions in companion specimens. Results are presented on the comparative deformation and rupture behavior of selected points in the base metal and weldment regions of the different specimens and on the overall surface strains for selected specimens

  20. Labyrinth-type domain structure of heteroepitaxial SrMnO2.5 film

    Science.gov (United States)

    Kobayashi, Shunsuke; Ikuhara, Yuichi; Yamamoto, Takahisa

    2013-06-01

    SrMnO2.5 films grown on SrTiO3 and LSAT substrates were prepared and oxygen vacancies in the films were directly confirmed by annular bright-field imaging in a scanning transmission electron microscope. The SrMnO2.5 films show a unique maze like pattern of domains, i.e., a labyrinth-type domain structure, that arises from relaxation of strain induced by lattice mismatches. The behavior of the domain widths is explained by the geometrical relationship for estimating of the average distance of misfit dislocations. We present useful principles for controlling the domain structures with a view to potential practical applications.

  1. Electronic structure of ionic PbFCl-type compounds under pressure

    CERN Document Server

    Kanchana, V; Rajagopalan, M

    2003-01-01

    The electronic structures of alkaline-earth fluoro-halides - SrFBr, SrFI, and CaFBr, which crystallize in the PbFCl-type structure - have been studied using the tight-binding linear muffin-tin orbital method within the local density approximation. The total energies were calculated using the atomic sphere approximation and were used to determine the ground state properties of these systems. The calculated ground state properties agree fairly well with the experimental results. These systems were found to be direct band gap insulators. The pressure dependence of the band gap was also studied. The band gap closes at high pressures leading to band overlap. A possible reason for the metallization in these compounds is discussed.

  2. On the Structural Types of Reduplicative in The Book of Songs

    Directory of Open Access Journals (Sweden)

    Binghua DONG

    2011-12-01

    Full Text Available

    The Book of Songs is a collection of poems and songs in Chinese Qin Dynasty, in which featured by a lot of using of reduplicative. This paper, based on the results of previous scholars, analyzes the structural types of reduplicative inThe Book of Songsfrom the aspects of reduplicative in radical, in rhymes and both. This paper is aimed to better understand the meaning of The Book of Songs, so as to improve language teaching and practical using, as well as help with corpus and theories.

    Key words: The Book of Songs; Reduplicative; Structure; Reduplicative in radical; Reduplicative in rhymes

  3. Structure of zeolite catalysis of the pentasil type, modified simultaneously by boron and phosphorus compounds

    Energy Technology Data Exchange (ETDEWEB)

    Kubasov, A.A.; Kitaev, L.E.; Koldasheva, E.M.; Revokatov, O.P.; Petrusevich, Yu.M.

    1989-02-01

    Using x-ray phase analysis, IR and /sup 11/B NMR spectroscopy, the authors have studied the structure of pentasil type zeolites modified by boron and phosphorus compounds. They show that the modifier is chemically bonded to the zeolite, but does not displace the tetrahedrally coordinated atoms of the zeolite lattice. They observe BO/sub 3/ and BO/sub 4/ groups. The formation of BO/sub 4/ is explained by formation of borophosphate, and also by interaction of the B-containing component with OH groups of the zeolite. The presence of BO/sub 3/ is due to the boron anhydride impurity. They suggest the possibility of formation of polyphosphate structures also.

  4. Structural changes in human type I collagen fibrils investigated by force spectroscopy

    International Nuclear Information System (INIS)

    In the field of biomechanics, collagen fibrils are believed to be robust mechanical structures characterized by a low extensibility. Until very recently, information on the mechanical properties of collagen fibrils could only be derived from ensemble measurements performed on complete tissues such as bone, skin, and tendon. Here, we measure force-elongation/relaxation profiles of single collagen fibrils using atomic force microscopy (AFM)-based force spectroscopy (FS). The elongation profiles show that in vitro-assembled human type I collagen fibrils are characterized by a large extensibility. Numerous discontinuities and a plateau in the force profile indicate major reorganization occurring within the fibrils in the 1.5- to 4.5-nN range. Our study demonstrates that newly assembled collagen fibrils are robust structures with a significant reserve of elasticity that could play a determinant role in the extracellular matrix (ECM) remodeling associated with tissue growth and morphogenesis

  5. Structure, function, evolution, and application of bacterial Pnu-type vitamin transporters.

    Science.gov (United States)

    Jaehme, Michael; Slotboom, Dirk Jan

    2015-09-01

    Many bacteria can take up vitamins from the environment via specific transport machineries. Uptake is essential for organisms that lack complete vitamin biosynthesis pathways, but even in the presence of biosynthesis routes uptake is likely preferred, because it is energetically less costly. Pnu transporters represent a class of membrane transporters for a diverse set of B-type vitamins. They were identified 30 years ago and catalyze transport by the mechanism of facilitated diffusion, without direct coupling to ATP hydrolysis or transport of coupling ions. Instead, directionality is achieved by metabolic trapping, in which the vitamin substrate is converted into a derivative that cannot be transported, for instance by phosphorylation. The recent crystal structure of the nicotinamide riboside transporter PnuC has provided the first insights in substrate recognition and selectivity. Here, we will summarize the current knowledge about the function, structure, and evolution of Pnu transporters. Additionally, we will highlight their role for potential biotechnological and pharmaceutical applications. PMID:26352203

  6. Heterotic and type II orientifold compactifications on SU(3) structure manifolds

    Energy Technology Data Exchange (ETDEWEB)

    Benmachiche, I.

    2006-07-15

    We study the four-dimensional N=1 effective theories of generic SU(3) structure compactifications in the presence of background fluxes. For heterotic and type IIA/B orientifold theories, the N=1 characteristic data are determined by a Kaluza-Klein reduction of the fermionic actions. The Kaehler potentials, superpotentials and the D-terms are entirely encoded by geometrical data of the internal manifold. The background flux and the intrinsic torsion of the SU(3) structure manifold, gives rise to contributions to the four-dimensional F-terms. The corresponding superpotentials generalize the Gukov-Vafa-Witten superpotential. For the heterotic compactification, the four-dimensional fermionic supersymmetry variations, as well as the conditions on supersymmetric vacua, are determined. The Yukawa couplings of the theory turn out to be similar to their Calabi-Yau counterparts. (Orig.)

  7. Creep deformation and rupture behavior of type 304/308 stainless steel structural weldments

    Energy Technology Data Exchange (ETDEWEB)

    McAfee, W.J.; Richardson, M.; Sartory, W.K.

    1977-05-12

    The creep deformation and rupture of type 304/308 stainless steel structural weldments at 593/sup 0/C (1100/sup 0/F) was experimentally investigated to study the comparative behavior of the base metal and weld metal constituents. The tests were conducted in support of ORNL's program to develop high-temperature structural design methods applicable to liquid-metal fast breeder reactor (LMFBR) system components that operate in the creep range. The specimens used were thin-walled, right circular cylinders capped with either flat or hemispherical heads and tested under internal gas pressure. Circumferential welds were located in different regions of the cylinder or head and, with one exception, were geometrically duplicated by all base metal regions in companion specimens. Results are presented on the comparative deformation and rupture behavior of selected points in the base metal and weldment regions of the different specimens and on the overall surface strains for selected specimens.

  8. Relationships between NDVI, canopy structure, and photosynthesis in three California vegetation types

    International Nuclear Information System (INIS)

    In a range of plant species from three Californian vegetation types, we examined the widely used ''normalized difference vegetation index'' (NDVI) and ''simple ratio'' (SR) as indicators of canopy structure, light absorption, and photosynthetic activity. These indices, which are derived from canopy reflectance in the red and near-infrared wavebands, highlighted phenological differences between evergreen and deciduous canopies. They were poor indicators of total canopy biomass due to the varying abundance of non-green standing biomass in these vegetation types. However, in sparse canopies (leaf area index (LAI) apprxeq 0-2), NDVI was a sensitive indicator of canopy structure and chemical content (green biomass, green leaf area index, chlorophyll content, and foliar nitrogen content). At higher canopy green LAI values ( gt 2; typical of dense shrubs and trees), NDVI was relatively insensitive to changes in canopy structure. Compared to SR, NDVI was better correlated with indicators of canopy structure and chemical content, but was equivalent to the logarithm of SR. In agreement with theoretical expectations, both NDVI and SR exhibited near-linear correlations with fractional PAR intercepted by green leaves over a wide range of canopy densities. Maximum daily photosynthetic rates were positively correlated with NDVI and SR in annual grassland and semideciduous shrubs where canopy development and photosynthetic activity were in synchrony. The indices were also correlated with peak springtime canopy photosynthetic rates in evergreens. However, over most of the year, these indices were poor predictors of photosynthetic performance in evergreen species due to seasonal reductions in photosynthetic radiation-use efficiency that occurred without substantial declines in canopy greenness. Our results support the use of these vegetation indices as remote indicators of PAR absorption, and thus potential photosynthetic activity, even in heterogeneous landscapes. To provide accurate estimates of vegetation atmosphere gas fluxes, remote NDVI and SR measurements need to be coupled with careful estimates of canopy photosynthetic radiation-use efficiency. (author)

  9. Temperature dependence of the local structure and lattice dynamics of wurtzite-type ZnO

    International Nuclear Information System (INIS)

    Temperature-dependent (10–300 K) Zn K-edge extended X-ray absorption fine structure (EXAFS) spectra of polycrystalline wurtzite-type ZnO were analyzed using ab initio multiple-scattering theory and taking into account anisotropy of the crystallographic structure and thermal disorder. We employed two different simulation approaches: classical molecular dynamics (MD) and reverse Monte Carlo coupled with an evolutionary algorithm (RMC/EA method). The accuracy of several force-field models, which are commonly used in the MD simulations of bulk and nanostructured ZnO, was tested based on a comparison between the experimental and simulated Zn K-edge EXAFS spectra. It was found that available force-field models fail to describe accurately many-atom distribution functions. A more accurate solution was obtained with the RMC/EA method, which allowed us also to resolve the non-equivalent groups of atoms in the first two coordination shells around the absorbing Zn atom and to follow the changes of structural parameters as the temperature varied. It was found that upon increasing temperature the structure of ZnO becomes more anisotropic due to the increase of internal parameter u of the oxygen Wyckoff position (2b) and related Zn0–O2 distances

  10. Shear strength in corner region of reinforced concrete duct type structures to be embedded in soil

    International Nuclear Information System (INIS)

    Reinforced concrete ducts for accommodating emergency cooling water pipes are generally embedded in soil. The structures is classified as one of the most important structures in terms of earthquake resistant design. During a strong earthquake it is subjected to shear deformations in concerted movement with surrounding soil. The comer regions of the duct should be designed against shear with moment combined. However, the complicated stress conditions in the region render the design more intricate in comparison with the case of simple determinate RC beam type structures. With the above situation in mind an experimental study was conducted, in which prototype as well as one half scale models representing the stress conditions in the region of interest were loaded and brought to failure in shear. The cross section of the prototype test model without shear reinforcements was 60 (height) x 30cm (width), and the tensile reinforcement ratio was 2.58%. The following results were obtained within the limit of the experimental study. (1) The shear capacity predicted by Japanese Design Code for linear RC members over-estimated the experimental ones with a considerably large safety margin of 4.4-5.0. (2) An improved design procedure to be applied to the specific structure was proposed, which gave a reasonable safety factor against shear failure of 1.7-2.0. (3) Combined smeared and discrete cracking model was utilized to simulate the shear failure mechanism, which could realistically pursue experimental behaviors. (author)

  11. UNIFIED CONTROL STRUCTURE OF MULTI-TYPE INTERIOR PERMANENT MAGNET MOTOR

    Directory of Open Access Journals (Sweden)

    M. NORHISAM

    2015-03-01

    Full Text Available This paper presents the control strategy structure to extract the speed torque characteristic for the newly designed three phase Multi Type Interior Permanent Magnet Motor. The proposed structure with the driving circuits exhibit the performance of torque characteristics of the stepper motor and brushless motor with independent coil winding per phase especially used as an in-wheel motor in agricultural applications. Brushless Direct Current motors exhibit characteristics of generating high torque at high speed while the Permanent Magnet Stepper motors has characteristic of generating high torque at low speed. The typical characteristics of the above two are integrated in the proposed structure with a complex control structure that handle the switching complexity and speed control in real time. Thus, a specially designed driving system is essential to drive and control this special motor. The evaluation of the motor mechanical characteristics when applying load torque is also presented. The result determines the practical torque range applicable for each motor configuration and as combined machine.

  12. Structural and functional cardiac changes in myotonic dystrophy type 1: a cardiovascular magnetic resonance study

    Directory of Open Access Journals (Sweden)

    Hermans Mieke CE

    2012-07-01

    Full Text Available Abstract Background Myotonic dystrophy type 1 (MD1 is a neuromuscular disorder with potential involvement of the heart and increased risk of sudden death. Considering the importance of cardiomyopathy as a predictor of prognosis, we aimed to systematically evaluate and describe structural and functional cardiac alterations in patients with MD1. Methods Eighty MD1 patients underwent physical examination, electrocardiography (ECG, echocardiography and cardiovascular magnetic resonance (CMR. Blood samples were taken for determination of NT-proBNP plasma levels and CTG repeat length. Results Functional and structural abnormalities were detected in 35 patients (44%. Left ventricular systolic dysfunction was found in 20 cases, left ventricular dilatation in 7 patients, and left ventricular hypertrophy in 6 patients. Myocardial fibrosis was seen in 10 patients (12.5%. In general, patients had low left ventricular mass indexes. Right ventricular involvement was uncommon and only seen together with left ventricular abnormalities. Functional or structural cardiac involvement was associated with age (p = 0.04, male gender (p Conclusions CMR can be useful to detect early structural and functional myocardial abnormalities in patients with MD1. Myocardial involvement is strongly associated with conduction abnormalities, but a normal ECG does not exclude myocardial alterations. These findings lend support to the hypothesis that MD1 patients have a complex cardiac phenotype, including both myocardial and conduction system alteration.

  13. The solar type protostar IRAS16293-2422: new constraints on the physical structure

    CERN Document Server

    Crimier, Nicolas; Maret, Sebastien; Bottinelli, Sandrine; Caux, Emmanuel; Kahane, Claudine; Lis, Dariusz C; Olofsson, Johan

    2010-01-01

    Context: The low mass protostar IRAS16293-2422 is a prototype Class 0 source with respect to the studies of the chemical structure during the initial phases of life of Solar type stars. Aims: In order to derive an accurate chemical structure, a precise determination of the source physical structure is required. The scope of the present work is the derivation of the structure of IRAS16293-2422. Methods: We have re-analyzed all available continuum data (single dish and interferometric, from millimeter to MIR) to derive accurate density and dust temperature profiles. Using ISO observations of water, we have also reconstructed the gas temperature profile. Results: Our analysis shows that the envelope surrounding IRAS16293-2422 is well described by the Shu "inside-out" collapsing envelope model or a single power-law density profile with index equal to 1.8. In contrast to some previous studies, our analysis does not show evidence of a large (>/- 800 AU in diameter) cavity. Conclusions: Although IRAS16293-2422 is a ...

  14. Structure of a microsporidian methionine aminopeptidase type 2 complexed with fumagillin and TNP-470

    Energy Technology Data Exchange (ETDEWEB)

    Alvarado, J.; Nemkal, A; Sauder, J; Russell, M; Akiyoshi, D; Shi, W; Almo, S; Weiss, L

    2009-01-01

    Microsporidia are protists that have been reported to cause infections in both vertebrates and invertebrates. They have emerged as human pathogens particularly in patients that are immunosuppressed and cases of gastrointestinal infection, encephalitis, keratitis, sinusitis, myositis and disseminated infection are well described in the literature. While benzimidazoles are active against many species of microsporidia, these drugs do not have significant activity against Enterocytozoon bieneusi. Fumagillin and its analogues have been demonstrated to have activity in vitro and in animal models of microsporidiosis and human infections due to E. bieneusi. Fumagillin and its analogues inhibit methionine aminopeptidase type 2. Encephalitozoon cuniculi MetAP2 (EcMetAP2) was cloned and expressed as an active enzyme using a baculovirus system. The crystal structure of EcMetAP2 was determined with and without the bound inhibitors fumagillin and TNP-470. This structure classifies EcMetAP2 as a member of the MetAP2c family. The EcMetAP2 structure was used to generate a homology model of the E. bieneusi MetAP2. Comparison of microsporidian MetAP2 structures with human MetAP2 provides insights into the design of inhibitors that might exhibit specificity for microsporidian MetAP2.

  15. Local structure and effective pair potential of rock-salt type and disordered rock-salt type AgI under pressure

    International Nuclear Information System (INIS)

    X-ray absorption fine structure (XAFS) observations on iodine K edge of AgI have been performed under high pressure and high temperature up to 6.0 GPa and 1000K to investigate the local structure and effective potentials in high pressure phases. In EXAFS analysis, we have directly carried out the numerical integration of EXAFS function. The anharmonic effective pair potentials V(u)=au2/2+bu3/3! for I-Ag bond have been determined under pressures. ?-AgI and disordered rock-salt type phase have super-ionic conduction behaviors. Ag ions occupy both octahedral and tetrahedral sites in the disordered phase and twenty percent of Ag ions occupy the tetrahedral site as a maximum value at 2GPa. The transition between the rock-salt type and disordered rock-salt type phases is a broad disorder type within the same structure. From the viewpoint of the local structure analyses on XANES and EXAFS spectra, some sudden changes are recognized near the phase transition point. Pressure influences greatly the effective pair potential of anti-bonding side and anharmonicity decreases with increasing pressure. Phonon dispersion relation of the rock-salt type AgI under pressure has been derived from EXAFS experiments. Analysis of EXAFS Debye-Waller factor is useful because the force constant can be decided directly even at high pressure and high temperature

  16. Crystal structure of Eu-doped magnetoplumbite-type lanthanum aluminum oxynitride with emission site splitting

    International Nuclear Information System (INIS)

    Eu-doped lanthanum aluminum oxynitride (LaAl12(O,N)19) with magnetoplumbite structure was prepared by nitridation of the oxide precursor obtained from aluminum glycine gel and subsequent post-annealing. Eu-doped lanthanum aluminum oxynitride exhibited blue light emission at 440 nm with a shoulder at 464 nm under excitation at 254 nm. Isostructural Eu-doped calcium aluminum oxide (CaAl12O19) exhibited a single emission peak at 415 nm. Structural refinement using neutron powder diffraction indicated that the lanthanum site occupied partially by Eu2+ splits into 2d and 6h sites in the aluminum oxynitride. The longer emission and the shoulder peak in the former aluminum oxynitride were observed in relation to the increasing covalency as well as crystal field splitting around doped Eu2+ induced by site splitting involved with the two kinds of anions. - Graphical Abstract: Magnetoplumbite type Eu-doped lanthanum aluminum oxynitride has lanthanum site splitting induced by two kinds of anions, causing two emission peaks. Highlights: ? Magnetoplumbite type LaAl12(O,N)19 doped with Eu shows emission peak splitting. ? ND analysis is performed on La0.97Eu0.03Al12(O,N)19 and Ca0.97Eu0.03Al12O19. ? La0.97Eu0.03Al12(O,N)19 has lanthanum site splitting. ? The lanthanum site splitting is induced by coexisting of two kinds of anions.

  17. Nuclear Structure and the Fate of Core Collapse (Type II) Supernova

    CERN Document Server

    Gai, Moshe

    2014-01-01

    For a long time Gerry Brown and his collaborator Hans Bethe considered the question of the final fate of a core collapse (Type II) supernova. Recalling ideas from nuclear structure on Kaon condensate and a soft equation of state of the dense nuclear matter they concluded that progenitor stars with mass as low a 17-18M$_\\odot$ (including supernova 1987A) could collapse to a small mass black hole with a mass just beyond 1.5M$_\\odot$, the upper bound they derive for a neutron star. We discuss another nuclear structure effect that determines the carbon to oxygen ratio (C/O) at the end of helium burning. This ratio also determines the fate of a Type II supernova with a carbon rich progenitor star producing a neutron star and oxygen rich collapsing to a black hole. While the C/O ratio is one of the most important nuclear input to stellar evolution it is still not known with sufficient accuracy. We discuss future efforts to measure with gamma-beam and TPC detector the 12C(a,g)16O reaction that determines the C/O rat...

  18. Nuclear structure and the fate of core collapse (Type II) supernova

    International Nuclear Information System (INIS)

    For a long time Gerry Brown and his collaborator Hans Bethe considered the question of the final fate of a core collapse (Type II) supernova. Recalling ideas from nuclear structure on Kaon condensate and a soft equation of state of the dense nuclear matter they concluded that progenitor stars with mass as low as 17–18M⊙ (including supernova 1987A) could collapse to a small mass black hole with a mass just beyond 1.5M⊙, the upper bound they derive for a neutron star. We discuss another nuclear structure effect that determines the carbon to oxygen ratio (C/O) at the end of helium burning. This ratio also determines the fate of a Type II supernova with a carbon rich progenitor star producing a neutron star and oxygen rich collapsing to a black hole. While the C/O ratio is one of the most important nuclear inputs to stellar evolution it is still not known with sufficient accuracy. We discuss future efforts to measure with gamma-beam and TPC detector of the 12C(α,γ)16O reaction that determines the C/O ratio in stellar helium burning

  19. Nuclear structure and the fate of core collapse (Type II) supernova

    Science.gov (United States)

    Gai, Moshe

    2014-08-01

    For a long time Gerry Brown and his collaborator Hans Bethe considered the question of the final fate of a core collapse (Type II) supernova. Recalling ideas from nuclear structure on Kaon condensate and a soft equation of state of the dense nuclear matter they concluded that progenitor stars with mass as low as 17-18M⊙ (including supernova 1987A) could collapse to a small mass black hole with a mass just beyond 1.5M⊙, the upper bound they derive for a neutron star. We discuss another nuclear structure effect that determines the carbon to oxygen ratio (C/O) at the end of helium burning. This ratio also determines the fate of a Type II supernova with a carbon rich progenitor star producing a neutron star and oxygen rich collapsing to a black hole. While the C/O ratio is one of the most important nuclear inputs to stellar evolution it is still not known with sufficient accuracy. We discuss future efforts to measure with gamma-beam and TPC detector of the C12(α,γ)O16 reaction that determines the C/O ratio in stellar helium burning.

  20. Characteristics of sandwich-type structural elements built of advanced composite materials from three dimensional fabrics

    Directory of Open Access Journals (Sweden)

    Castejón, L.

    1997-12-01

    Full Text Available Sandwich-type structures have proved to be alternatives of great success for several fields of application, and specially in the building sector. This is due to their outstanding properties of .specific rigidity and strength against bending loads and other range of advantages like fatigue and impact resistance, attainment of flat and smooth surfaces, high electric and thermal insulation, design versatility and some others. However, traditional sandwich structures present problems like their tendency towards delamination, stress concentrations in bores or screwed Joints, and pre resistance. These problems are alleviated thanks to the use of new sandwich structures built using three dimensional structures of advanced composite materials, maintaining the present advantages for more traditional sandwich structures. At this rate, these new structures can be applied in several areas where conventional sandwich structures used to be like walls, partitions, floor and ceiling structures, domes, vaults and dwellings, but with greater success.

    Las estructuras tipo sándwich han demostrado ser alternativas de gran éxito para diversos campos de aplicación y, en concreto, en el sector de la construcción, listo es gracias a sus excelentes propiedades de rigidez y resistencia específica frente a cargas de flexión y otra larga lista de ventajas, a la que pertenecen, por ejemplo, su buena resistencia a fatiga, resistencia al impacto, obtención de superficies lisas y suaves, elevado aislamiento térmico y eléctrico, versatilidad de diseño y otras. Sin embargo, las estructuras sándwich, tradicionales presentan una problemática consistente en su tendencia a la delaminación, concentraciones de tensiones ¿aparecidas ante la existencia de agujeros o uniones atornilladas y resistencia al fuego. Estos problemas son pifiados gracias a la aplicación de estructuras novedosas tipo sándwich, construidas a partir de tejidos tridimensionales de materiales compuestos avanzados, manteniéndose las ventajas existentes para las estructuras sándwich tradicionales. De este modo, estas nuevas estructuras pueden ser aplicadas en diversas áreas donde se venían aplicando las estructuras sándwich convencionales, pero con mayor éxito. Como son muros, tabiques, suelos, bóvedas, cúpulas, estructuras de suelo y techo y viviendas.

  1. Determination of protein folding kinetic types using sequence and predicted secondary structure and solvent accessibility.

    Science.gov (United States)

    Zhang, Hua; Zhang, Tuo; Gao, Jianzhao; Ruan, Jishou; Shen, Shiyi; Kurgan, Lukasz

    2012-01-01

    Proteins fold through a two-state (TS), with no visible intermediates, or a multi-state (MS), via at least one intermediate, process. We analyze sequence-derived factors that determine folding types by introducing a novel sequence-based folding type predictor called FOKIT. This method implements a logistic regression model with six input features which hybridize information concerning amino acid composition and predicted secondary structure and solvent accessibility. FOKIT provides predictions with average Matthews correlation coefficient (MCC) between 0.58 and 0.91 measured using out-of-sample tests on four benchmark datasets. These results are shown to be competitive or better than results of four modern predictors. We also show that FOKIT outperforms these methods when predicting chains that share low similarity with the chains used to build the model, which is an important advantage given the limited number of annotated chains. We demonstrate that inclusion of solvent accessibility helps in discrimination of the folding kinetic types and that three of the features constitute statistically significant markers that differentiate TS and MS folders. We found that the increased content of exposed Trp and buried Leu are indicative of the MS folding, which implies that the exposure/burial of certain hydrophobic residues may play important role in the formation of the folding intermediates. Our conclusions are supported by two case studies. PMID:21082205

  2. Structural, dielectric, magnetic, and nuclear magnetic resonance studies of multiferroic Y-type hexaferrites

    Science.gov (United States)

    Khanduri, H.; Chandra Dimri, M.; Kooskora, H.; Heinmaa, I.; Viola, G.; Ning, H.; Reece, M. J.; Krustok, J.; Stern, R.

    2012-10-01

    The effect of strontium substitution on structural, magnetic, and dielectric properties of a multiferroic Y-type hexaferrite (chemical formula Ba2-xSrxMg2Fe12O22 with 0 ? x ? 2) was investigated. Y-type hexaferrite phase formation was not affected by strontium substitution for barium, in the range 0 ? x ? 1.5, confirmed by x-ray diffraction and Raman spectroscopy measured at room temperature. Two intermediate magnetic spin phase transitions (at tempertures TI and TII) and a ferrimagnetic-paramagnetic transition (at Curie temperature TC) were identified from the temperature dependence of the magnetic susceptibility. Magnetic transition temperatures (TI, TII, and TC) increased with increasing strontium content. Magnetic hysteresis measurements indicated that by increasing strontium concentration, the coercivity increases, while the saturation magnetization decreases. The 57Fe NMR spectrum of the Y-type hexaferrite measured at 5 K and in zero magnetic field showed remarkable differences compared to that of other hexaferrites due to their different number of tetrahedral and octahedral iron sites. The temperature and frequency dependence of the dielectric permittivity evidenced broad peaks with frequency dispersion in correspondence of the Curie temperature.

  3. A method for evaluating structural transducers used in Type B package testing

    Science.gov (United States)

    Madsen, Marcella M.; Uncapher, William L.; Bronowski, David R.; Stenberg, Duane R.

    1989-01-01

    As a result of an agreement between DOE and the Nuclear Regulatory Commission (NRC), each transport cask must be certified by the NRC. To meet these requirements, OCRWM is undertaking a program to design, test, certify, and fabricate a variety of cask systems. Design verification tests will be performed by the cask contractor to demonstrate design safety and to aid in cask certification by the NRC. During Type B packaging design verification testing designers may verify analytical calculations with instrumentation data. Many packagings are tested with accelerometers and strain gages, collectively known as transducers, that measure structural response. Accelerometers measure acceleration and strain gages measure surface strain at the mounted location. This paper describes a method developed for OCRWM to evaluate various transducers of these two types that have been suggested for use in design verification testing. Typically transducers are characterized by the manufacturer under laboratory conditions. In this program ruggedness, failure frequency, repeatability, and manufacturer's data under field and laboratory conditions were investigated. Specific cask model test require transducers with specific ranges; transducers of the selected types were procured with ranges appropriate for this test.

  4. Structure and electrical properties of p-type twin ZnTe nanowires

    International Nuclear Information System (INIS)

    Resonant tunneling is firstly found in twin p-type ZnTe nanowire field-effect transistors. The twin ZnTe nanowires are synthesized via the thermal evaporation process. X-ray diffraction and high-resolution transmission electron microscopy characterization indicate that the as-grown twin nanowire has a zinc-blende crystal structure with an integrated growth direction of [11-1]. The twin plane is (11-1) and the angle between the mirror symmetrical planes is 141 . The formation of twins is attributed to the surface tension from the eutectic liquid droplet. Field-effect transistors based on single ZnTe twin nanowire are constructed, the corresponding electrical measurements demonstrate that the twin nanowires have a p-type conductivity with a mobility (?h) of 0.11 cm 2 V -1 S -1, and a carrier concentration (nh) of 1.1 x 10 17 cm -3. Significantly, the negative differential resistance with a peak-to-valley current ratio of about 1.3 is observed in p-type twin ZnTe nanowire field-effect transistors at room temperature. As the periodic barriers produced in the periodic twin interfaces can form multi-barrier and multi-well along one-dimensional direction. The multibarrier can be modulated under external electrical field. When the resonant condition is met, the space charge will be enhanced with the inherent feedback mechanism, and the resonant tunneling will occur. (orig.)

  5. Types of structural chromosome aberrations and their incidences in human spermatozoa X-irradiated in vitro

    International Nuclear Information System (INIS)

    The authors studied the effects of in vitro X-irradiation on human sperm chromosomes, using our interspecific in vitro fertilization system between human spermatozoa and zona-free hamster oocytes. 28 semen samples from 5 healthy men were exposed to 0.23, 0.45, 0.91 and 1.82 Gy of X-rays. Totals of 2098 and 2862 spermatozoa were karyotyped in the control and the irradiated groups, respectively. The indicence of spermatozoa with X-ray-induced structural chromosome aberrations (Y) increased linearly with increasing dosage (D), being best expressed by the equation, Y = 0.08 + 34.52 D. The incidence of breakage-type aberrations was moe than 9 times higher than that of exchange-type aberrations. Both of them showed linear dose-dependent increases, which were expressed by the regression lines, Y = -0.014 + 0.478 D and Y -0.010 + 0.057 D, respectively. The incidence of chromosome-ltype aberrations was about 6 times higher than that of chromatid-type aberrations. Their dose-dependent increases were expressed by the regression lines, Y = -0.015 + 0.462 D and Y = -0.006 + 0.079 D, respectively. These results are discussed in relation to the previous data obtained with ?-rays. The repair mechanism of X-ray-induced sperm DNA lesions is also discussed. (author). 21 refs.; 4 figs.; 4 tabs

  6. Synthesis, structural transformation, thermal stability, valence state, and magnetic and electronic properties of PbNiO3 with perovskite- and LiNbO3-type structures.

    Science.gov (United States)

    Inaguma, Yoshiyuki; Tanaka, Kie; Tsuchiya, Takeshi; Mori, Daisuke; Katsumata, Tetsuhiro; Ohba, Tomonori; Hiraki, Ko-ichi; Takahashi, Toshihiro; Saitoh, Hiroyuki

    2011-10-26

    We synthesized two high-pressure polymorphs PbNiO(3) with different structures, a perovskite-type and a LiNbO(3)-type structure, and investigated their formation behavior, detailed structure, structural transformation, thermal stability, valence state of cations, and magnetic and electronic properties. A perovskite-type PbNiO(3) synthesized at 800 °C under a pressure of 3 GPa crystallizes as an orthorhombic GdFeO(3)-type structure with a space group Pnma. The reaction under high pressure was monitored by an in situ energy dispersive X-ray diffraction experiment, which revealed that a perovskit-type phase was formed even at 400 °C under 3 GPa. The obtained perovskite-type phase irreversibly transforms to a LiNbO(3)-type phase with an acentric space group R3c by heat treatment at ambient pressure. The Rietveld structural refinement using synchrotron X-ray diffraction data and the XPS measurement for both the perovskite- and the LiNbO(3)-type phases reveal that both phases possess the valence state of Pb(4+)Ni(2+)O(3). Perovskite-type PbNiO(3) is the first example of the Pb(4+)M(2+)O(3) series, and the first example of the perovskite containing a tetravalent A-site cation without lone pair electrons. The magnetic susceptibility measurement shows that the perovskite- and LiNbO(3)-type PbNiO(3) undergo antiferromagnetic transition at 225 and 205 K, respectively. Both the perovskite- and LiNbO(3)-type phases exhibit semiconducting behavior. PMID:21888429

  7. Myotonic Dystrophy Type 1 RNA Crystal Structures Reveal Heterogeneous 1 × 1 Nucleotide UU Internal Loop Conformations

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Amit; Park, HaJeung; Fang, Pengfei; Parkesh, Raman; Guo, Min; Nettles, Kendall W.; Disney, Matthew D. (Scripps)

    2012-03-27

    RNA internal loops often display a variety of conformations in solution. Herein, we visualize conformational heterogeneity in the context of the 5'CUG/3'GUC repeat motif present in the RNA that causes myotonic dystrophy type 1 (DM1). Specifically, two crystal structures of a model DM1 triplet repeating construct, 5'r[{und UU}GGGC(C{und U}G){sub 3}GUCC]{sub 2}, refined to 2.20 and 1.52 {angstrom} resolution are disclosed. Here, differences in the orientation of the 5' dangling UU end between the two structures induce changes in the backbone groove width, which reveals that noncanonical 1 x 1 nucleotide UU internal loops can display an ensemble of pairing conformations. In the 2.20 {angstrom} structure, CUGa, the 5' UU forms a one hydrogen-bonded pair with a 5' UU of a neighboring helix in the unit cell to form a pseudoinfinite helix. The central 1 x 1 nucleotide UU internal loop has no hydrogen bonds, while the terminal 1 x 1 nucleotide UU internal loops each form a one-hydrogen bond pair. In the 1.52 {angstrom} structure, CUGb, the 5' UU dangling end is tucked into the major groove of the duplex. While the canonically paired bases show no change in base pairing, in CUGb the terminal 1 x 1 nucleotide UU internal loops now form two hydrogen-bonded pairs. Thus, the shift in the major groove induced by the 5' UU dangling end alters noncanonical base patterns. Collectively, these structures indicate that 1 x 1 nucleotide UU internal loops in DM1 may sample multiple conformations in vivo. This observation has implications for the recognition of this RNA, and other repeating transcripts, by protein and small molecule ligands.

  8. Structures and properties of ThCr2Si2-type superconductors and related materials

    International Nuclear Information System (INIS)

    Work on this thesis started in 2008, only a few months after the discovery of superconductivity in doped BaFe2As2. The first goal at that time was the investigation of further compounds crystallizing in the ThCr2Si2-type structure with respect to phase transitions, magnetic properties and possible superconductivity. One candidate that seemed to be very similar to BaFe2As2 because of its structural phase transitions, was SrRh2As2. However, a closer look revealed a more complicated and challenging structural chemistry. The first two chapters of this work are devoted to the study and solution of the intriguing crystallographic problems of the three SrRh2As2 phases and the characterization of further ternary rhodium arsenides. Furthermore, high quality single crystals of Ba1-xKxFe2As2 were synthesized and single crystals as well as powder samples of Ba1-xKxFe2As2 were investigated with synchrotron X-ray diffraction methods as described in chapters 5 and 6. Finally, the last part of this thesis concentrates on the question which effects of doping are actually responsible for the occurrence of superconductivity in BaFe2As2. Is the superconductivity induced by the alteration of charge in the FeAs4/4-layer, by the disorder introduced by doping, or by the structural changes? To help elucidate this issue, several substitution series of 122-iron arsenides were prepared and the influence of hole and electron or charge and isoelectronic doping on superconductivity, magnetic and structural properties and their mutual relationship was studied (chapters 7,8,9 and 10).

  9. High-pressure synthesis of ferromagnetic Mn3Ge with the Cu3Au-type structure

    Science.gov (United States)

    Takizawa, H.; Yamashita, T.; Uheda, K.; Endo, T.

    2002-11-01

    A new intermetallic compound, Mn3Ge, has been synthesized by direct reaction of elemental components at 6.2 GPa and 1000°C for 30 min using a belt-type high-pressure apparatus. The compound crystallizes into a cubic structure with the space group Pm3m, namely the L12-type (Cu3Au-type) structure. The structure was refined by Rietveld analysis of the powder x-ray diffraction data and the lattice constant was determined as a = 0.380 19(3) nm. The compound shows metallic conductivity and ferromagnetism with a Curie temperature of 400 K.

  10. Simultaneous type I and type II ?erenkov-phase matched second-harmonic generation in disordered nonlinear photonic structures.

    Science.gov (United States)

    Ayoub, Mousa; Paßlick, Markus; Imbrock, Jörg; Denz, Cornelia

    2015-11-01

    We observe simultaneous type I and II ?erenkov-phase matched second-harmonic generation in a disordered nonlinear photonic crystal. The mean width of the disordered ferroelectric domains and the laser beam width are adjusted to be on the same length scale. We analyze the polarization properties, emission angles and intensities of each process. PMID:26561107

  11. Musical structural determinants of emotional judgments in dementia of the Alzheimer type.

    Science.gov (United States)

    Gagnon, Lise; Peretz, Isabelle; Fülöp, Tamàs

    2009-01-01

    People with dementia of the Alzheimer type (DAT) may well be emotionally soothed by listening to music. However, very few systematic studies have been conducted to support the anecdotal evidence. DAT does damage certain cerebral structures that subsume emotional processing, and some studies have demonstrated deficits affecting emotional judgments of facial expression and prosody in DAT. Accordingly, this study addressed the question of whether DAT might leave musical emotional judgment intact. Twelve early DAT participants and 12 healthy elderly participants took part in this study. Emotional judgments were examined in relation to mode and tempo, two important structural properties that contribute to the happy-sad distinction in music. Their respective contributions were assessed in four different experimental conditions. The DAT participants' responses were similar to those of healthy elderly participants, showing spared ability to employ tempo and mode as cues for emotional interpretation. The DAT participants' performance was not correlated with their global cognitive functioning. These results constitute a preliminary empirical demonstration that, in early DAT, musical emotional judgments appear to be based on normal structural analysis of musical input. PMID:19210036

  12. Optimization of chemical structure of Schottky-type selection diode for crossbar resistive memory.

    Science.gov (United States)

    Kim, Gun Hwan; Lee, Jong Ho; Jeon, Woojin; Song, Seul Ji; Seok, Jun Yeong; Yoon, Jung Ho; Yoon, Kyung Jean; Park, Tae Joo; Hwang, Cheol Seong

    2012-10-24

    The electrical performances of Pt/TiO(2)/Ti/Pt stacked Schottky-type diode (SD) was systematically examined, and this performance is dependent on the chemical structures of the each layer and their interfaces. The Ti layers containing a tolerable amount of oxygen showed metallic electrical conduction characteristics, which was confirmed by sheet resistance measurement with elevating the temperature, transmission line measurement (TLM), and Auger electron spectroscopy (AES) analysis. However, the chemical structure of SD stack and resulting electrical properties were crucially affected by the dissolved oxygen concentration in the Ti layers. The lower oxidation potential of the Ti layer with initially higher oxygen concentration suppressed the oxygen deficiency of the overlying TiO(2) layer induced by consumption of the oxygen from TiO(2) layer. This structure results in the lower reverse current of SDs without significant degradation of forward-state current. Conductive atomic force microscopy (CAFM) analysis showed the current conduction through the local conduction paths in the presented SDs, which guarantees a sufficient forward-current density as a selection device for highly integrated crossbar array resistive memory. PMID:22999222

  13. Crystal structure of a copper-transporting PIB-type ATPase

    DEFF Research Database (Denmark)

    Gourdon, Pontus Emanuel; Liu, Xiang-Yu

    2011-01-01

    Heavy-metal homeostasis and detoxification is crucial for cell viability. P-type ATPases of the class IB (PIB) are essential in these processes, actively extruding heavy metals from the cytoplasm of cells. Here we present the structure of a PIB-ATPase, a Legionella pneumophila CopA Cu(+)-ATPase, in a copper-free form, as determined by X-ray crystallography at 3.2 Å resolution. The structure indicates a three-stage copper transport pathway involving several conserved residues. A PIB-specific transmembrane helix kinks at a double-glycine motif displaying an amphipathic helix that lines a putative copper entry point at the intracellular interface. Comparisons to Ca(2+)-ATPase suggest an ATPase-coupled copper release mechanism from the binding sites in the membrane via an extracellular exit site. The structure also provides a framework to analyse missense mutations in the human ATP7A and ATP7B proteins associated with Menkes' and Wilson's diseases.

  14. Single crystal and magnetic structures of maricite-type AgMnVO4

    Science.gov (United States)

    Ben Yahia, Hamdi; Shikano, Masahiro; Gaudin, Etienne; Avdeev, Maxim; Ling, Chris D.

    2015-01-01

    Single crystals of the ternary manganese vanadate AgMnVO4, were grown using AgVO3 flux. The structure was determined from single crystal X-ray diffraction data. The magnetic structure and properties of AgMnVO4 were characterized by magnetic susceptibility, specific heat, and low-temperature neutron powder diffraction measurements. AgMnVO4 crystallizes in the maricite-type structure with space group Pnma, a=9.5393(12), b=6.8132(9), c=5.3315(7) Å and Z=4. AgMnVO4 contains MnO4 chains made up of edge-sharing MnO6 octahedra, and these chains are interlinked by the VO4 and AgO4 tetrahedra. The specific heat measurements indicate a 3D-antiferromagnetic ordering at ~12.1 K and the neutron powder diffraction measurements at 5 K show that the Mn2+magnetic moments are antiferromagnetically coupled within the chains which are antiferromagnetically coupled to each other.

  15. Two Types of Dynamic Cool Coronal Structures Observed with STEREO and HINODE

    CERN Document Server

    Zhang, J

    2009-01-01

    Solar coronal loops show significant plasma motions during their formation and eruption stages. Dynamic cool coronal structures, on the other hand, are often observed to propagate along coronal loops. In this paper, we report on the discovery of two types of dynamic cool coronal structures, and characterize their fundamental properties. Using the EUV 304 angstrom images from the Extreme UltraViolet Imager (EUVI) telescope on the Solar TErrestrial RElation Observatory (STEREO) and the Ca II filtergrams from the Solar Optical Telescope (SOT) instrument on HINODE, we study the evolution of an EUV arch and the kinematics of cool coronal structures. The EUV 304 angstrom observations show that a missile-like plasmoid moves along an arch-shaped trajectory, with an average velocity of 31 km/s. About three hours later, a plasma arch forms along the trajectory, subsequently the top part of the arch fades away and disappears, meanwhile the plasma belonging to the two legs of the arch flows downward to the arch feet. Dur...

  16. Crystallographic Structure of Porcine Adenovirus Type 4 Fiber Head and Galectin Domains?

    Science.gov (United States)

    Guardado-Calvo, Pablo; Muñoz, Eva M.; Llamas-Saiz, Antonio L.; Fox, Gavin C.; Kahn, Richard; Curiel, David T.; Glasgow, Joel N.; van Raaij, Mark J.

    2010-01-01

    Adenovirus isolate NADC-1, a strain of porcine adenovirus type 4, has a fiber containing an N-terminal virus attachment region, shaft and head domains, and a C-terminal galectin domain connected to the head by an RGD-containing sequence. The crystal structure of the head domain is similar to previously solved adenovirus fiber head domains, but specific residues for binding the coxsackievirus and adenovirus receptor (CAR), CD46, or sialic acid are not conserved. The structure of the galectin domain reveals an interaction interface between its two carbohydrate recognition domains, locating both sugar binding sites face to face. Sequence evidence suggests other tandem-repeat galectins have the same arrangement. We show that the galectin domain binds carbohydrates containing lactose and N-acetyl-lactosamine units, and we present structures of the galectin domain with lactose, N-acetyl-lactosamine, 3-aminopropyl-lacto-N-neotetraose, and 2-aminoethyl-tri(N-acetyl-lactosamine), confirming the domain as a bona fide galectin domain. PMID:20686025

  17. Crystallographic structure of porcine adenovirus type 4 fiber head and galectin domains.

    Science.gov (United States)

    Guardado-Calvo, Pablo; Muñoz, Eva M; Llamas-Saiz, Antonio L; Fox, Gavin C; Kahn, Richard; Curiel, David T; Glasgow, Joel N; van Raaij, Mark J

    2010-10-01

    Adenovirus isolate NADC-1, a strain of porcine adenovirus type 4, has a fiber containing an N-terminal virus attachment region, shaft and head domains, and a C-terminal galectin domain connected to the head by an RGD-containing sequence. The crystal structure of the head domain is similar to previously solved adenovirus fiber head domains, but specific residues for binding the coxsackievirus and adenovirus receptor (CAR), CD46, or sialic acid are not conserved. The structure of the galectin domain reveals an interaction interface between its two carbohydrate recognition domains, locating both sugar binding sites face to face. Sequence evidence suggests other tandem-repeat galectins have the same arrangement. We show that the galectin domain binds carbohydrates containing lactose and N-acetyl-lactosamine units, and we present structures of the galectin domain with lactose, N-acetyl-lactosamine, 3-aminopropyl-lacto-N-neotetraose, and 2-aminoethyl-tri(N-acetyl-lactosamine), confirming the domain as a bona fide galectin domain. PMID:20686025

  18. Crystal chemistry of Ruddlesden-Popper type structures in high Tc ceramic superconductors

    International Nuclear Information System (INIS)

    Similar structural patterns have been noticed in the systems La-Cu-O, La-Ni-O and Bi and Tl-containing superconducting oxides. The formation of Ruddlesden-Popper type layers (alternating slabs of rocksalt and perovskite strucutres) is seen in these oxides which is similar in many respects to what is seen in the system Sr-Ti-O. However, there are some significant differences, for example the rocksalt and perovskite blocks in new superconducting compounds are not necessarily electrically neutral, unlike in the Sr-Ti-O system. It, thus, becomes necessary to create oxygen vacancies in the basic perovskite structure of Bi-containing compounds, when the width of the perovskite slab changes on addition of extra Cu-O planes. Results of atomistic simulations suggest that these missing oxygen ions allows the Cu-O planes to buckle in Bi-series of compounds. This is also supported by the absence of buckling in the Sr-Ti-O series of compounds and the first member of Bi-containing compounds in which there are no missing oxygen ions. Additional results on the phase stability of polytypoid structure in la-Cu-O system and defect chemistry of compounds of LaNi-O system are presented. (author). 14 re fs., 7 figs., 4 tabs

  19. Structure of a bacterial type III secretion system in contact with a host membrane in situ

    Science.gov (United States)

    Nans, Andrea; Kudryashev, Mikhail; Saibil, Helen R.; Hayward, Richard D.

    2015-12-01

    Many bacterial pathogens of animals and plants use a conserved type III secretion system (T3SS) to inject virulence effector proteins directly into eukaryotic cells to subvert host functions. Contact with host membranes is critical for T3SS activation, yet little is known about T3SS architecture in this state or the conformational changes that drive effector translocation. Here we use cryo-electron tomography and sub-tomogram averaging to derive the intact structure of the primordial Chlamydia trachomatis T3SS in the presence and absence of host membrane contact. Comparison of the averaged structures demonstrates a marked compaction of the basal body (4 nm) occurs when the needle tip contacts the host cell membrane. This compaction is coupled to a stabilization of the cytosolic sorting platform-ATPase. Our findings reveal the first structure of a bacterial T3SS from a major human pathogen engaged with a eukaryotic host, and reveal striking `pump-action' conformational changes that underpin effector injection.

  20. Inelastic response of PCRV structure model with star-type support under horizontal loads

    International Nuclear Information System (INIS)

    The report presents the test results of scaled models for prestressed concrete reactor vessel (PCRV) structure with star-shaped support under horizontal loads. A scale factor of 1/70 to a proto-type PCRV structure for large HTGR is used for both static and dynamic loading test models, while a 1/15 scaled model is used for static loading tests. The static behaviors such as a load-deflection envelope of the 1/70 model are predicted well by an inelastic analysis in consideration with appearance of concrete cracks and reinforcing bar yielding. It is also ascertained by the test results of the 1/15 model under static alternative loads that the same analysis procedure can be applicable to the evaluation of the elastic and inelastic behaviors of PCRV structure with support. Based on the static loading test results of both scaled models, a tri-linearized load-deflection envelope and an equivalent linearized mathematical model for hysteresis loop are assumed in a dynamic analysis. A dynamic response analysis of the 1/70 model subjected to earthquake-like base motion is conducted by the similar manner above-mentioned and the calculated results show a good correlation with the test results

  1. Synthesis, structural and morphological characterization of Ca{sub 0}.45Eu{sub 0}.05Zr{sub 2}(PO{sub 4}){sub 3} nano phosphors; Sintesis, caracterizacion estructural y morfologica de nanofosforos Ca {sub 0},45Eu{sub 0},05Zr{sub 2}(PO{sub 4}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Alcaraz, L.; Isasi, J.; Peiteado, M.; Cabalero, A.

    2015-07-01

    Ca{sub 0}.45Eu{sub 0}.05Zr{sub 2}(PO{sub 4}){sub 3} samples were synthesized by a preparation process in two step: a sol-gel method using two pH values, acid (pH ? 2) and basic pH (? 10), and a subsequent treatment of the precursor powders in a N{sub 2}:H{sub 2} (90:10) flow in order to stabilized 2+ oxidation state of europium. X-ray diffraction patterns exhibit diffraction maxima typical of NASICON type structure of rhombohedral symmetry and space group R-3. Most intense diffraction maxima are seen for the samples prepared in a basic reaction medium. Magnetic measurements confirm 2+ oxidation state of europium cations in the synthesized samples. Microscopy images show particles of spherical shape and nano metric size according to X-ray diffraction results, indicating that these samples may be useful in certain luminescent devices. (Author)

  2. The influence of type-I and type-II triplet multiple quantum well structure on white organic light-emitting diodes.

    Science.gov (United States)

    Zhao, Bo; Su, Zisheng; Li, Wenlian; Chu, Bei; Jin, Fangming; Yan, Xingwu; Zhang, Tianyou; Zhang, Feng; Fan, Di; Gao, Yuan; Wang, Junbo; Pi, Huachun; Zhu, Jianzhuo

    2013-01-01

    We demonstrate high-efficient white organic light-emitting diodes (WOLEDs) based on triplet multiple quantum well (MQW) structure and focus on the influence on WOLEDs through employing different potential barrier materials to form type-I and type-II MQWs, respectively. It is found that type-I MQW structure WOLEDs based on 1,3,5-tris(N-phenyl-benzimidazol-2-yl)benzene as potential barrier layer (PBL) offers high electroluminescent (EL) performance. That is to say, maximum current efficiency and power efficiency are achieved at about 1,000 cd/m2 with 16.4 cd/A and 8.3 lm/W, which increase by 53.3% and 50.9% over traditional three-layer structure WOLEDs, respectively, and a maximum luminance of 17,700 cd/m2 is earned simultaneously. The achievement of high EL performance would be attributed to uniform distribution and better confinement of carriers within the emitting layer (EML). However, when 4,7-diphenyl-1,10-phenanthroline or 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline is used as PBL to form type-II MQW structure, poor EL performance is obtained. We attribute that to improper energy level alignment between the interface of EML/PBL, which leads to incomplete confinement and low recombination efficiency of carriers, a more detailed mechanism was argued. PMID:24341599

  3. How to Compare, Analyze, and Morph Between Crystal Structures of Different Conformations: The P-Type ATPase Example.

    Science.gov (United States)

    Karlsen, Jesper L; Bublitz, Maike

    2016-01-01

    In the past 15 years, a large body of structural information on P-type ATPases has accumulated in the Protein Data Bank. The available crystal structures cover different enzymes in a variety of conformational states that are associated with the enzymatic activity of ATP-dependent ion translocation across membranes. This chapter provides an overview about the available structural information, along with some practical instructions on how to make meaningful comparisons of structures in different conformations, and how to generate morphs between series of structures, in order to analyze domain movements and structural flexibility. PMID:26695058

  4. Structural basis for promiscuous PAM recognition in type I-E Cascade from E. coli.

    Science.gov (United States)

    Hayes, Robert P; Xiao, Yibei; Ding, Fran; van Erp, Paul B G; Rajashankar, Kanagalaghatta; Bailey, Scott; Wiedenheft, Blake; Ke, Ailong

    2016-02-25

    Clustered regularly interspaced short palindromic repeats (CRISPRs) and the cas (CRISPR-associated) operon form an RNA-based adaptive immune system against foreign genetic elements in prokaryotes. Type I accounts for 95% of CRISPR systems, and has been used to control gene expression and cell fate. During CRISPR RNA (crRNA)-guided interference, Cascade (CRISPR-associated complex for antiviral defence) facilitates the crRNA-guided invasion of double-stranded DNA for complementary base-pairing with the target DNA strand while displacing the non-target strand, forming an R-loop. Cas3, which has nuclease and helicase activities, is subsequently recruited to degrade two DNA strands. A protospacer adjacent motif (PAM) sequence flanking target DNA is crucial for self versus foreign discrimination. Here we present the 2.45 Å crystal structure of Escherichia coli Cascade bound to a foreign double-stranded DNA target. The 5'-ATG PAM is recognized in duplex form, from the minor groove side, by three structural features in the Cascade Cse1 subunit. The promiscuity inherent to minor groove DNA recognition rationalizes the observation that a single Cascade complex can respond to several distinct PAM sequences. Optimal PAM recognition coincides with wedge insertion, initiating directional target DNA strand unwinding to allow segmented base-pairing with crRNA. The non-target strand is guided along a parallel path 25 Å apart, and the R-loop structure is further stabilized by locking this strand behind the Cse2 dimer. These observations provide the structural basis for understanding the PAM-dependent directional R-loop formation process. PMID:26863189

  5. Glomerular structural-functional relationship models of diabetic nephropathy are robust in type 1 diabetic patients.

    Science.gov (United States)

    Mauer, Michael; Caramori, Maria Luiza; Fioretto, Paola; Najafian, Behzad

    2015-06-01

    Studies of structural-functional relationships have improved understanding of the natural history of diabetic nephropathy (DN). However, in order to consider structural end points for clinical trials, the robustness of the resultant models needs to be verified. This study examined whether structural-functional relationship models derived from a large cohort of type 1 diabetic (T1D) patients with a wide range of renal function are robust. The predictability of models derived from multiple regression analysis and piecewise linear regression analysis was also compared. T1D patients (n = 161) with research renal biopsies were divided into two equal groups matched for albumin excretion rate (AER). Models to explain AER and glomerular filtration rate (GFR) by classical DN lesions in one group (T1D-model, or T1D-M) were applied to the other group (T1D-test, or T1D-T) and regression analyses were performed. T1D-M-derived models explained 70 and 63% of AER variance and 32 and 21% of GFR variance in T1D-M and T1D-T, respectively, supporting the substantial robustness of the models. Piecewise linear regression analyses substantially improved predictability of the models with 83% of AER variance and 66% of GFR variance explained by classical DN glomerular lesions alone. These studies demonstrate that DN structural-functional relationship models are robust, and if appropriate models are used, glomerular lesions alone explain a major proportion of AER and GFR variance in T1D patients. PMID:25183630

  6. The response of the pyrochlore structure-type to ion-beam irradiation

    Science.gov (United States)

    Lian, Jie

    Pyrochlore with the general formula of A3+2B4+2O7 (Fd3m; Z = 8) has been proposed as the candidate waste form for the immobilization of actinides, particularly plutonium from dismantled nuclear weapons. Because actinides decay by alpha-decay events, radiation effects on the waste form are a concern. The effects of radiation on different pyrochlore compositions, A2B2O7 (A = La ˜ Lu, and Y; B = Ti, Sn, and Zr), have been investigated by 50 KeV He+, 600 KeV Ar+, 1.0 MeV Kr+, and 1.5 MeV Xe+ ion irradiations. Titanate pyrochlores are generally sensitive to ion beam damage and can be amorphized at a low damage level (˜0.2 dpa). The critical amorphization temperature, Tc, increases from ˜480 to ˜1120 K with increasing A-site cation size. A dramatically increasing radiation "resistance" to ion beam induced-amorphization has been observed with increasing Zr-content in the Gd2Ti2-xZrxO7 system. The pure end-member, Gd2Zr2O7, cannot be amorphized, even at doses as high as ˜100 dpa. Although zirconate pyrochlores are generally considered to be radiation "resistant", ion beam-induced amorphization occurs for La2Zr2O7 at a dose of ˜5.5 dpa at room temperature. Stannate pyrochlores A2Sn 2O7 (A = La, Nd, Gd) are readily amorphized by ion beam damage at a relatively low dose (˜1 dpa) at room temperature; while no evidence of amorphization has been observed in A2Sn2O7 (A = Er, Y, Lu) irradiated with 1 MeV Kr+ ions at a dose of ˜6 dpa at 25 K. The factors that influence the response of different pyrochlore compositions to ion irradiation-induced amorphization are discussed in terms of cation radius ratio, defect formation energies, and the tendency of the pyrochlore structure-type to undergo an order-disorder transition to the defect-fluorite structure. The "resistance" of the pyrochlore structure to ion beam-induced amorphization is not only affected by the relative sizes of the A- and B-site cations, but also the cation electronic configurations. Pyrochlore compositions that have larger structural deviations from the ideal fluorite structure are more sensitive to ion beam-induced amorphization. These fundamental results provide insight into the structural and compositional controls on radiation-induced amorphization of pyrochlores. This understanding can be used for the design and selection of materials used for the immobilization of actinides.

  7. Evidence for alternative quaternary structure in a bacterial Type III secretion system chaperone

    Energy Technology Data Exchange (ETDEWEB)

    Barta, Michael L.; Zhang, Lingling; Picking, Wendy L.; Geisbrecht, Brian V. (UMKC); (OKLU)

    2010-10-05

    Type III secretion systems are a common virulence mechanism in many Gram-negative bacterial pathogens. These systems use a nanomachine resembling a molecular needle and syringe to provide an energized conduit for the translocation of effector proteins from the bacterial cytoplasm to the host cell cytoplasm for the benefit of the pathogen. Prior to translocation specialized chaperones maintain proper effector protein conformation. The class II chaperone, Invasion plasmid gene (Ipg) C, stabilizes two pore forming translocator proteins. IpgC exists as a functional dimer to facilitate the mutually exclusive binding of both translocators. In this study, we present the 3.3 {angstrom} crystal structure of an amino-terminally truncated form (residues 10-155, denoted IpgC10-155) of the class II chaperone IpgC from Shigella flexneri. Our structure demonstrates an alternative quaternary arrangement to that previously described for a carboxy-terminally truncated variant of IpgC (IpgC{sup 1-151}). Specifically, we observe a rotationally-symmetric 'head-to-head' dimerization interface that is far more similar to that previously described for SycD from Yersinia enterocolitica than to IpgC1-151. The IpgC structure presented here displays major differences in the amino terminal region, where extended coil-like structures are seen, as opposed to the short, ordered alpha helices and asymmetric dimerization interface seen within IpgC{sup 1-151}. Despite these differences, however, both modes of dimerization support chaperone activity, as judged by a copurification assay with a recombinant form of the translocator protein, IpaB. Conclusions: From primary to quaternary structure, these results presented here suggest that a symmetric dimerization interface is conserved across bacterial class II chaperones. In light of previous data which have described the structure and function of asymmetric dimerization, our results raise the possibility that class II chaperones may transition between asymmetric and symmetric dimers in response to changes in either biochemical modifications (e.g. proteolytic cleavage) or other biological cues. Such transitions may contribute to the broad range of protein-protein interactions and functions attributed to class II chaperones.

  8. Evidence for alternative quaternary structure in a bacterial Type III secretion system chaperone

    Directory of Open Access Journals (Sweden)

    Picking Wendy L

    2010-07-01

    Full Text Available Abstract Background Type III secretion systems are a common virulence mechanism in many Gram-negative bacterial pathogens. These systems use a nanomachine resembling a molecular needle and syringe to provide an energized conduit for the translocation of effector proteins from the bacterial cytoplasm to the host cell cytoplasm for the benefit of the pathogen. Prior to translocation specialized chaperones maintain proper effector protein conformation. The class II chaperone, Invasion plasmid gene (Ipg C, stabilizes two pore forming translocator proteins. IpgC exists as a functional dimer to facilitate the mutually exclusive binding of both translocators. Results In this study, we present the 3.3 Å crystal structure of an amino-terminally truncated form (residues 10-155, denoted IpgC10-155 of the class II chaperone IpgC from Shigella flexneri. Our structure demonstrates an alternative quaternary arrangement to that previously described for a carboxy-terminally truncated variant of IpgC (IpgC1-151. Specifically, we observe a rotationally-symmetric "head-to- head" dimerization interface that is far more similar to that previously described for SycD from Yersinia enterocolitica than to IpgC1-151. The IpgC structure presented here displays major differences in the amino terminal region, where extended coil-like structures are seen, as opposed to the short, ordered alpha helices and asymmetric dimerization interface seen within IpgC1-151. Despite these differences, however, both modes of dimerization support chaperone activity, as judged by a copurification assay with a recombinant form of the translocator protein, IpaB. Conclusions From primary to quaternary structure, these results presented here suggest that a symmetric dimerization interface is conserved across bacterial class II chaperones. In light of previous data which have described the structure and function of asymmetric dimerization, our results raise the possibility that class II chaperones may transition between asymmetric and symmetric dimers in response to changes in either biochemical modifications (e.g. proteolytic cleavage or other biological cues. Such transitions may contribute to the broad range of protein-protein interactions and functions attributed to class II chaperones.

  9. OMP-type Algorithm with Structured Sparsity Patterns for Multipath Radar Signals

    CERN Document Server

    Rebafka, Tabea; Charbit, Maurice

    2011-01-01

    A transmitted, unknown radar signal is observed at the receiver through more than one path in additive noise. The aim is to recover the waveform of the intercepted signal and to simultaneously estimate the direction of arrival (DOA). We propose an approach exploiting the parsimonious time-frequency representation of the signal by applying a new OMP-type algorithm for structured sparsity patterns. An important issue is the scalability of the proposed algorithm since high-dimensional models shall be used for radar signals. Monte-Carlo simulations for modulated signals illustrate the good performance of the method even for low signal-to-noise ratios and a gain of 20 dB for the DOA estimation compared to some elementary method.

  10. Crystal structure of distorted fluorite-type SrU2O6 with pentavalent uranium

    International Nuclear Information System (INIS)

    Electron paramagnetic resonance absorption (EPR) of SrU2O6, in which the strontium and uranium atoms randomly occupy the metal sites of the fluorite-type crystal, showed a slightly anisotropic signal. In relation with this anomalous signal, the crystal structure of SrU2O6 has been analyzed by powder X-ray diffraction and Rietveld refinement. The sample has been found to consist of two phases with 73% and 27% in mass percent. The major phase crystallized in nearly cubic symmetry with slight rhombohedral distortion (a=3.8642 A and ?=60.096 ), whereas the other showed a significant rhombohedral distortion from cubic symmetry, i.e. a=3.8334 A and ?=62.024 . Consequently, the existence of these two phases has been considered to be one of the possible origins which introduce the observed anisotropic signal of EPR. (orig.)

  11. Photoinduced domain-type collective structural changes with interlayer ? -bonds in the visible region of graphite

    Science.gov (United States)

    Ohnishi, Hiromasa; Nasu, Keiichiro

    2009-02-01

    We theoretically study the photoinduced domain-type structural changes in the visible region of graphite. By means of the ab initio total-energy calculation, we clarify the adiabatic path for the nucleation of this domain, wherein the interlayer distance of the original graphite is contracted and new interlayer ? -bonds are induced with a certain periodic buckling pattern. We show that an excitation by few visible photons is energetically enough to trigger the formation of this domain, and this domain is sufficiently stable against the thermal fluctuation at around room temperature. The electronic state of this domain is also shown to have a pseudogap, characteristic to an insulator immersed in the original semimetallic graphite.

  12. (1/2+1/2+1) cell structure type RF gun

    International Nuclear Information System (INIS)

    In order to suppress the back bombardment of electrons in RF thermionic guns, a new kind of on axis coupled structure type RF gun was developed. It is composed of two half cells and a full cell. The first half cell is shortened and a half cell is inserted between the first half cell and the main accelerating cell to defocus the particles moving backwards with highest energy, thus the cathode back bombardment power is strongly reduced. For the field stability the ?/2 mode is chosen. The electromagnetic field analytical codes SUPERFISH and PAMELA are mainly used to do the calculation and simulation. The average back bombardment power is about 3.6 W, assuming the pulse width of 6 ?s and a repetition rate of 25 Hz. (author)

  13. Analytical assessment of shear rigidity degradation of embedded box-type reinforced concrete structures

    International Nuclear Information System (INIS)

    Investigation of the behavior of embedded box-type reinforced concrete (RC) structures for nuclear power stations subjected to lateral earthquake earth pressure, concerning shear rigidity and its reduction, has been conducted analytically in this study. A nonlinear finite element approach based on smeared crack model of RC plate element was utilized. From the parametric study of a real RC duct for accommodating emergency cooling water pipes in nuclear power stations, it was found that lower reduced shear rigidity factor, which was defined as the ratio of reduced and initial shear rigidity, could be attained by arranging lower concrete compressive strength, higher yield strength of reinforcing bar, higher reinforcement ratio and thinner wall thickness of the RC duct. Finally, a formula to predict the reduced shear rigidity factor has been proposed based on the parametric study. (author)

  14. Application of SMA rod to exposed-type column base in smart structural system

    Science.gov (United States)

    Tamai, Hiroyuki; Miura, Kenji; Kitagawa, Yoshikazu; Fukuta, Toshibumi

    2003-08-01

    A seismic-resistant member with a shape memory alloy (SMA) rod was used in an exposed-type column base as a passive damper for building structures. Horizontal and vertical loading tests on the column base with SMA anchorage were done with increasing drift amplitude to investigate the restoring force characteristics of the column base. The results showed that (1) use of an SMA rod prevents deterioration of the restoring force characteristics, (2) use of an appropriate SMA material and a moderate-size rod can yield large deformation capacity and good restoring force characteristics, and (3) after a large drift in the building frame, SMA anchorage enables the original shape and resisting performance to recover with unloading.

  15. Genetic-Structural relations in some types of spanish uranium deposits

    International Nuclear Information System (INIS)

    On the spanish hercynian areas there are different types of uraniferous deposits, which may be classified in the following groups: Group I, high temperature magmatic deposits, Group II, low temperature veins and Group III supergenic deposits, generated by weathering of the former ones or by lixiviation of the intra granitic uranium. The deposits belonging to Group I are founding the hercynian ge anticlinal; those of Groups II and III, chiefly in the eugeosyncline. The explanation suggested for these genetic-structural relationships assumes that, in the ge anticlinal, uranium would migrate from the dioritic magmas to form and high temperature deposits. In the eugeosyncline, a large fraction of the uranium would migrate towards more differentiated granites, in which it might partially remain or from which it might have been finally concentrated in the epithermal veins or by later tectonic actions. The Group III deposits ar more frequent in the eugeosyncline, due to the greater abundance of more differentiated intrusive rocks. (Author) 16 refs

  16. Topology of large-scale structure by galaxy type hydrodynamic simulations

    CERN Document Server

    Gott, J R; Ostriker, J P; Gott, J Richard; Cen, Renyue; Ostriker, Jeremiah P

    1995-01-01

    The topology of large scale structure is studied as a function of galaxy type using the genus statistic. In hydrodynamical cosmological CDM simulations, galaxies form on caustic surfaces (Zeldovich pancakes) then slowly drain onto filaments and clusters. The earliest forming galaxies in the simulations (defined as ``ellipticals") are thus seen at the present epoch preferentially in clusters (tending toward a meatball topology), while the latest forming galaxies (defined as ``spirals") are seen currently in a spongelike topology. The topology is measured by the genus (= number of ``donut" holes - number of isolated regions) of the smoothed density-contour surfaces. The measured genus curve for all galaxies as a function of density obeys approximately the theoretical curve expected for random-phase initial conditions, but the early forming elliptical galaxies show a shift toward a meatball topology relative to the late forming spirals. Simulations using standard biasing schemes fail to show such an effect. Larg...

  17. Linear algebraic analyses of structures with one predominant type of anomalous scatterer

    International Nuclear Information System (INIS)

    Further studies have been made of the information content of the exact linear equations for analyzing anomalous dispersion data in one-wavelength experiments. The case of interest concerns structures containing atoms that essentially do not scatter anomalously and one type of anomalously scattering atoms. For this case, there are three alternative ways of writing the equations. The alternative sets of equations and the transformations for transforming one set into the other are given explicitly. Comparison calculations were made with different sets of equations. Isomorphous replacement information is readily introduced into the calculations and the advantage of doing so is clearly illustrated by the results. Another aspect of the potential of the exact linear algebraic theory is its application to multiple-wavelength experiments. Successful applications of the latter have been made by several collaborative groups of investigators. (orig.)

  18. Subsonic structure of radiatively driven winds of early-type stars

    International Nuclear Information System (INIS)

    Methods are developed for the calculation of extended nongray model atmospheres for early-type stars with radiatively driven mass loss. Models for a central star of a planetary nebula and a Wolf-Rayet star are calculated, and compared with hydrostatic model calculations. Scaling laws are given for explaining the differences and similarities of stars of different stellar mass. It is found that transonic flow cannot occur if only continuum sources of opacity are present, because a moderate outward increase of the flux mean opacity is required for a physically acceptable structure. Observations of the Of star zeta Pup and the Wolf-Rayet star HD 50896 are summarized that indicate the continuum formation regions are spatially extended

  19. STRUCTURAL PERFORMANCE OF TWO TYPES OF WALL SLAB CONNECTION UNDER OUT-OF-PLANE LATERAL CYCLIC LOADING

    OpenAIRE

    AHMED ABDULRAZZAQ NASSER AL-AGHBARI; SITI HAWA HAMZAH; NOR HAYATI ABDUL HAMID; NURHANIZA ABDUL RAHMAN

    2012-01-01

    Currently, most of the high-rise buildings in Malaysia are constructed using tunnel form system. However, this type of structural system is still questionable of its safety under ground motion. Thus, the main objective of this study is to test and compare the structural performance of two types of wall-slab connection namely cross and anchorage bracings under reversible quasi-static cyclic loading. Two identical sub-assemblage of wall-slab connections are designed, constructed and tested in h...

  20. Measuring Mangrove Type, Structure And Carbon Storage With UAVSAR And ALOS/PALSAR Data

    Science.gov (United States)

    Fatoyinbo, T. E.; Cornforth, W.; Pinto, N.; Simard, M.; Pettorelli, N.

    2011-12-01

    Mangrove forests provide a great number of ecosystem services ranging from shoreline protection (e.g. against erosion, tsunamis and storms), nutrient cycling, fisheries production, building materials and habitat. Mangrove forests have been shown to store very large amounts of Carbon, both above and belowground, with storage capacities even greater than tropical rainforests. But as a result of their location and economic value, they are among the most rapidly changing landscapes in the World. Mangrove extent is limited 1) in total extent to tidally influenced coastal areas and 2) to tropical and subtropical regions. This can lead to difficulties mapping mangrove type (such as degraded vs non degraded, scrub vs tall, dense vs sparse) because of cloud cover and limited access to high-resolution optical data. To accurately quantify the effect of land use and climate change on tropical wetland ecosystems, we must develop effective mapping methodologies that take into account not only extent, but also the structure and health of the ecosystem. This must be done by including Synthetic Aperture Radar (SAR) data. In this research, we used L-band Synthetic Aperture Radar data from the ALOS/PALSAR and UAVSAR instruments over selected sites in the Americas (Sierpe, Costa Rica and Everglades, Florida)and Asia (Sundarbans). In particular, we used the SAR data in combination with other remotely sensed data and field data to 1) map mangrove extent 2) determine mangrove type, health and adjascent land use, and 3) estimate aboveground biomass and carbon storage for entire mangrove systems. We used different classification methodologies such as polarimetric decomposition, unsupervised classification and image segmentation to map mangrove type. Because of the high resolution of the radar data, and its ability to interact with forest volume, we are able to identify mangrove zones and differentiate between mangroves and other forests/land uses. We also integrated InSAR data (SRTM), spaceborne Lidar (GLAS) and field data, in combination with the SAR data to derive aboveground biomass and carbon storage in mangroves. We successfully produced maps of mangrove extent, type, health and carbon storage by using L-band SAR data. Our results show that both UAVSAR and ALOS/PALSAR data alone are effective datasets for mapping mangrove extent, type and other land use. By combining multiple datasets, we were able to determine mangrove biomass without an upper estimation limit and with low error.

  1. Observations of ion cyclotron harmonic structure in Type 1 to 4 VHF AURORAL ECHOES

    International Nuclear Information System (INIS)

    The understanding of E region plasma instabilities is crucial for the interpretation of the enormous stream of data from large ongoing projcets like STARE and SABRE in Europe, and BARS in Canada, in which measurements of radar scatter from E region plasma waves are used to infer the electric fields, hydromagnetic waves, and field-aligned currents in the E region. Auroral echoes measured by 50 MHz CW Doppler radars strongly indicate that the electrostatic ion cyclotron (EIC) mechanism may be more important in auroral irregularity formation than was previously suspected. Doppler spectra taken over 64 ms intervals are highly structured, showing as many as seven or eight discrete frequency components whose frequency separation is often approximately the cyclotron frequency of one of the principal ions in the E region. In this note, we show that when examples of each of the four standard spectral types (1 to 4), whose classification is based upon time-averaging over several seconds, are examined with the finer time resolution of 64 ms (i.e., a resolution of the same order as the lifetime of the individual plasma irregularities), all four types appear to be composites of many harmonically structured bursts as described above. Since the spectral components in individual bursts may occur at frequencies that are not exact multiples of the ion gyrofrequency, time averaging over many bursts usually smears out the harmonic content, resulting in broader spectral peaks. The resulting smoothed spectra then appear to be caused by instabilities other than the EIC instability. copyright American Geophysical Union 1988

  2. Passivation of W-structured type-II superlattice long-wave infrared photodiodes

    Science.gov (United States)

    Aifer, E. H.; Warner, J. H.; Stine, R. R.; Vurgaftman, I.; Canedy, C. L.; Jackson, E. M.; Tischler, J. G.; Meyer, J. R.; Petrovykh, D. Y.; Whitman, L. J.

    2007-04-01

    A critical step in developing type-II superlattice (T2SL) based LWIR focal plane array (FPA) technology is to achieve high performance levels in FPA pixel-sized devices having 20-40 μm pitch. At this scale, device performance tends to be limited by surface effects along mesa sidewalls which are etched to provide pixel isolation. While control of surface leakage has been achieved for MWIR T2SLs, as evidenced by the availability of commercially produced FPAs, the same cannot be said for LWIR T2SLs. Several groups have approached this problem as strictly a matter of surface treatment, including cleaning, chemical treatment, and dielectric coating or epitaxial overgrowth, but with limited success. Here we describe an approach based on shallow-etch mesa isolation (SEMI), which takes advantage of bandgap grading to isolate devices without exposing narrow-gap LWIR regions on diode mesas sidewalls. The SEMI process consists of defining mesa diodes with a shallow etch that passes only 20-100 nm past the junction of a graded-gap "W"-structured type-II superlattice p-i-n structure, where the bandgap remains large (>200 meV). A second, deeper etch is then used to define a trench along the chip border for access to the p-contact. As a result, SEMI diodes have only MWIR layers exposed along sidewalls, while the LWIR regions remain buried and unexposed. We also discuss an investigation of surface passivation of GaSb with sulfur using thioacetamide.

  3. Electronic structure and thermoelectric properties of n - and p -type SnSe from first-principles calculations

    Science.gov (United States)

    Kutorasinski, K.; Wiendlocha, B.; Kaprzyk, S.; Tobola, J.

    2015-05-01

    We present results of the electronic band structure, Fermi surface, and electron transport property calculations in the orthorhombic n - and p -type SnSe, applying the Korringa-Kohn-Rostoker method and the Boltzmann transport approach. The analysis accounted for the temperature effect on crystallographic parameters in P n m a structure as well as the phase transition to C m C m structure at Tc˜807 K. Remarkable modifications of the conduction and valence bands were noticed upon varying crystallographic parameters within the structure before Tc, while the phase transition mostly leads to the jump in the band-gap value. The diagonal components of the kinetic parameter tensors (velocity, effective mass) and resulting transport quantity tensors [electrical conductivity ? , thermopower S , and power factor (PF)] were computed for a wide range of temperature (15-900 K) and hole (p -type) and electron (n -type) concentrations (1017-1021cm-3 ). SnSe is shown to have a strong anisotropy of the electron transport properties for both types of charge conductivity, as expected for the layered structure, with the generally heavier p -type effective masses compared to n -type ones. Interestingly, p -type SnSe has strongly nonparabolic dispersion relations, with the "pudding-mold-like" shape of the highest valence band. The analysis of ? ,S , and PF tensors indicates that the interlayer electron transport is beneficial for thermoelectric performance in n -type SnSe, while this direction is blocked in p -type SnSe, where in-plane transport is preferred. Our results predict that n -type SnSe is potentially even better thermoelectric material than p -type SnSe. Theoretical results are compared with the single-crystal p -SnSe measurements, and good agreement is found below 600 K. The discrepancy between the computational and experimental data, appearing at higher temperatures, can be explained assuming an increase of the hole concentration versus T , which is correlated with the experimental Hall data.

  4. Four types of interference competition and their impacts on the ecology and evolution of size-structured populations and communities

    DEFF Research Database (Denmark)

    Zhang, Lai; Andersen, Ken Haste

    2015-01-01

    We investigate how four types of interference competition - which alternatively affect foraging, metabolism, survival, and reproduction - impact the ecology and evolution of size-structured populations. Even though all four types of interference competition reduce population biomass, interference competition at intermediate intensity sometimes significantly increases the abundance of adult individuals and the population[U+05F3]s reproduction rate. We find that foraging and metabolic interference evolutionarily favor smaller maturation size when interference is weak and larger maturation size when interference is strong. The evolutionary response to survival interference and reproductive interference is always larger maturation size. We also investigate how the four types of interference competition impact the evolutionary dynamics and resultant diversity and trophic structure of size-structured communities. Like other types of trait-mediated competition, all four types of interference competition can induce disruptive selection and thus promote initial diversification. Even though foraging interference and reproductive interference are more potent in promoting initial diversification, they catalyze the formation of diverse communities with complex trophic structure only at high levels of interference intensity. By contrast, survival interference does so already at intermediate levels, while reproductive interference can only support relatively smaller communities with simpler trophic structure. Taken together, our results show how the type and intensity of interference competition jointly affect coexistence patterns in structured population models

  5. Structure and stability of monazite- and zircon-type LaVO4 under hydrostatic pressure

    Science.gov (United States)

    Cheng, Xuerui; Guo, Dongjie; Feng, Shiquan; Yang, Kun; Wang, Yongqiang; Ren, Yufen; Song, Yang

    2015-11-01

    Pure monazite (m)- and zircon (t)-type LaVO4 and LaVO4:Eu3+ were successfully synthesized by a hydrothermal method. The high pressure behavior of m- and t-LaVO4 nanoparticles has been investigated using Raman scattering techniques at room temperature. Raman measurements reveal a slight change for m-LaVO4 at 11.2 GPa because of an isostructural phase transition. However, striking changes in Raman spectra indicate a pressure-induced irreversible phase transition from the zircon to monazite structure for t-LaVO4 at around 5.9 GPa. The evolution of the luminescence spectra of t-LaVO4:Eu3+ has also been studied during the pressure-induced phase transition. It is observed that pressure has a great influence on the fluorescence intensity and the energy levels, which allows a more in-depth understanding of the nature of the pressure-induced phase transition for t-LaVO4. This result further confirms the conclusion that zircon-type RVO4 compounds with larger rare-earth cations will experience zircon to monazite phase transition.

  6. Role of synthesis parameters on structural and electrical properties of M-type hexa-ferrites

    International Nuclear Information System (INIS)

    Phase purity, particle size and its distribution contributes a lot to the physical properties of M-type hexa-ferrites. These parameters are strongly influenced by the variation in synthesis parameters. In the present work, effect of synthesis parameters such as molar ratio (Fe/Sr) and volume rate of addition of precipitating agent on M-type hexa-ferrite (SrFe/sub 12/O/sub 19/) prepared by co-precipitation method have been investigated systematically. The molar ratio (Fe/Sr) in SrFe/sub 12/O/sub 19/ was varied as 12, 11, 10, 09, and 08. X-ray diffraction analysis revealed that molar ratio does not affect the phase purity. X-ray diffraction analysis of the samples prepared with different volume rate of addition of precipitating agent indicated that phase purity and micro-structural properties of SrFe/sub 12/O/sub 19/ are greatly influenced by the above synthesis parameter. High volume rate of addition of precipitating agent resulted in high phase purity, smaller particle size, and narrow particle size distribution. (author)

  7. Ce3+ incorporated structural and magnetic properties of M type barium hexaferrites

    International Nuclear Information System (INIS)

    M type barium hexaferrites BaCexFe12?xO19 (0?x?0.3) (BCFO) were synthesized by the sol–gel auto combination method. Optimum annealing temperature of hexagonal phase was determined by using the TGA analysis. The annealing temperature form the TGA is 1000 °C samples annealed 1000 °C for 5 h to produce M type hexaferrites. X-ray diffraction data run to full Prof Program (Winploter 2010) pattern indicate that samples are single phase hexagonal structure with space group P63/mmc. Lattice parameter ‘a’ and ‘c’ increase with increase in Ce content x. Results of field emission scanning electron microscope show that the grains are regular hexagonal platelets with sizes from 0.3 to 1.4 ?m. It is observed that from M–H curve value of the saturation magnetization and coercivity decreases with increasing x. Curie temperature from magnetization with temperature plot is found to decrease with Ce3+ substitution x due to decreases in magnetic interaction. - Highlights: • Ce3+ substituted Ba hexaferrites. • Increased coercivity with Ce3+ substitution. • Decrease in saturation magnetization and Curie temperature

  8. Cyclodextrins in pharmaceutical formulations I: structure and physicochemical properties, formation of complexes, and types of complex.

    Science.gov (United States)

    Jambhekar, Sunil S; Breen, Philip

    2016-02-01

    Cyclodextrins are cyclic oligosaccharides that have been recognized as pharmaceutical adjuvants for the past 20 years. The molecular structure of these glucose derivatives, which approximates a truncated cone, bucket, or torus, generates a hydrophilic exterior surface and a nonpolar interior cavity. Cyclodextrins can interact with appropriately sized drug molecules to yield an inclusion complex. These noncovalent inclusion complexes offer a variety of advantages over the noncomplexed form of a drug. Cyclodextrins are primarily used to enhance the aqueous solubility, physical chemical stability, and bioavailability of drugs. Their other applications include preventing drug-drug interactions, converting liquid drugs into microcrystalline powders, minimizing gastrointestinal and ocular irritation, and reducing or eliminating unpleasant taste and smell. Here, we discuss the physical chemical properties of various cyclodextrins, including the effects of substitutions on these properties. Additionally, we report on the regulatory status of their use, commercial products containing cyclodextrins, toxicological considerations, and the forces involved in complex formation. We also highlight the types of complex formed and discuss the methods used to determine the types of complex present. PMID:26686054

  9. Efficiency of different forest types in carbon storage depends on their internal structure

    Directory of Open Access Journals (Sweden)

    Iuliana F. Gheorghe

    2011-04-01

    Full Text Available Forest vegetation is a key factor in the maintenance of global carbon cycle balance under the present climate change conditions. Forest ecosystems are both buffers against extreme climatic events accompanying climate change and carbon sinks diminishing the environmental impact of anthropogenic greenhouse gas emissions. We investigated the influence of stand structure and site characteristics on the productivity and carbon storage capacity of temperate forest types. Predictors of species productivity were parameters such as stand density, age, height, average diameter and wood density. Morus alba (L. was more productive than average both in terms of annual volume increment and annual biomass gain, while Quercus sessiliflora (Matt. Lieb. and Quercus frainetto (Ten. were significantly less productive than average. Differences in stand productivity were explained by stand density, age, height, altitude, type of regeneration and species composition. Statistically significant differences were measured between the productivity of stands dominated by different woody species, with low productive stands dominated by slow growing species with high wood density like Quercus or Fagus, and highly productive stands rich in fast growing species with low wood density like Populus or Salix. Stands with different plant communities in the underlying herbaceous layer also tended to have different levels of productivity.

  10. Structural, dielectric and magnetic properties of Cd/Pb doped W-type hexaferrites

    Energy Technology Data Exchange (ETDEWEB)

    Hooda, Ashima; Sanghi, Sujata, E-mail: sutkash@yahoo.com; Agarwal, Ashish; Dahiya, Reetu

    2014-01-15

    W-type hexaferrites having compositions Ba(Zn{sub 0.5}Cd{sub 0.5}){sub 2}Fe{sub 16}O{sub 27} (BZCFO) and Ba(Zn{sub 0.5}Pb{sub 0.5}){sub 2}Fe{sub 16}O{sub 27} (BZPFO) were synthesized by solid state reaction method at high annealing temperature. Their dielectric and magnetic properties as a function of temperature and frequency have been studied. X-ray analysis confirms the presence of W-type hexaferrite phase structure. SEM analysis presented heterogeneous hexagonal shape and sizes of grains. Analysis of Nyquist plots of prepared samples revealed the contribution of electrically active regions corresponding to grains and grain boundaries. The reciprocal temperature dependence of dc electrical resistivity (?) satisfies the Arrhenius relation which depicted the semi-conducting behavior of the samples. The variation of dielectric constant (??) and dielectric loss (tan ?) with temperature (323 K–573 K) and frequency (1 kHz–5 MHz) are studied. Analysis of the experimental conductivity data and ‘s’ parameter shows that correlated barrier hopping (CBH) mechanism is the most probable mechanism of conduction for BZCFO sample; whereas for BZPFO hexaferrite, both correlated barrier hopping (CBH) and quantum mechanical tunneling (QMT) model are applicable for conduction. The BZCFO sample has higher value of saturation magnetization and lower coercivity than BZPFO sample due to the preference of Cd{sup 2+} for tetrahedral sites and decrease in number of spin-down magnetic ions. - Highlights: • W type Ba(Zn{sub 0.5}Cd{sub 0.5}){sub 2}Fe{sub 16}O{sub 27} and Ba(Zn{sub 0.5}Pb{sub 0.5}){sub 2}Fe{sub 16}O{sub 27} hexaferrites were prepared. • BZPFO has more resistivity and low values of ?{sub a.c.}, ?? and tan ? than BZCFO. • BZCFO has higher saturation magnetization and lower coercivity than BZPFO.

  11. The Electronic Structure of CdSe/CdS Core/Shell Seeded Nanorods: Type-I or Quasi-Type-II?

    CERN Document Server

    Eshet, Hagai; Rabani, Eran

    2013-01-01

    The electronic structure of CdSe/CdS core/shell seeded nanorods of experimentally relevant size is studied using a combination of molecular dynamics and semiempirical pseudopotential techniques, with the aim to address the transition from type-I to a quasi-type-II band alignment. The hole is found to be localized in the core region regardless of its size. When electron-hole interactions are neglected, we observe little overlap of electron density with the core region, consistent with type-II behavior. When electron-hole interactions are taken into account, we find that the overlap of the electron density with the core decreases with decreasing size, consistent with a transition to quasi-type II. We attribute this transition to an interplay of electron-hole interactions and volume effects, and not to band alignment. Our results provide insight to both scanning tunneling and optical measurements.

  12. The structure of Ksub(1.33)Mn8O16 and cation ordering in hollandite-type structures

    International Nuclear Information System (INIS)

    Crystal data: Msub(r)=747.5, tetragonal, I4/m, a=9.866(3), c=2.872(1) A, V=279.6(2) A3, Z=8(Ksub(0.167)MnO2), Dsub(x)=4.442 g cm-3, lambda(Ag K?, graphite monochromator)=0.56005 A, ?=49.9 cm-1, F(000)=353.5, T=295 K, final R=1.9% for 436 unique reflections. In this mixed-valence compound Ksub(x)Mn4+sub(x8)Mnsub(x)3+O16(x=1.33) the channel cation position (K+) is not at 001/2 but at 00z with z=0.375. It is shown that the symmetry of hollandite-type structures (Asub(x)B8O16) is determined by the relative sizes of the framework (B) and the channel (A) cations. Single-crystal rotation photographs around c show extra diffuse levels between reciprocal-lattice planes perpendicular to c. These extra levels, attributed to channel-cation ordering, have spacings which indicate that, in a given channel, the order involves three unit cells in the c direction. The presence of vacancies in the channels allows a relaxation of the K+ cations and a minimization of the K-K electrostatic repulsion via a displacement of the K+ cations from the centers of their square-prismatic channel sites toward the neighboring vacancies. It seems likely that either diffuse or superstructure reflections should occur in most Asub(x)B8O16 hollandite-type compounds studied so far. In the former case long-range ordering occurs among the A cations and vacancies along a given channel without a correlation between adjacent channels, as in Ksub(1.33)Mn9O16 where the K ordering is one-dimensional. In the latter case the ordering is accompanied by a strong correlation between channels leading to a three-dimensional ordering. (orig.)

  13. Ratios of hardness numbers in calculations of static and cyclical strength of structural types of steels ??????????? ????? ????????? ? ???????? ?? ??????????? ? ??????????? ????????? ??????????????? ??????

    Directory of Open Access Journals (Sweden)

    Gustov Yuriy Ivanovich

    2013-01-01

    Full Text Available Results of calculations of values of static and cyclical strength of steels used in the structural design and based on the method of experimental and analytical coordination of hardness numbers are presented in the article. Strength measurements taken on the basis of the Rockwell method make it possible to research into the strength characteristics of small-size samples of steel in cases of restoration and inspection of the technical condition of the metalwork. Besides, the Rockwell method is universal and faster than the Brinell method.Thus, the availability of hardness values of small-size samples makes it possible to provide a definition of standard indicators of static and cyclical strength. Moreover, development of the definition of structural and power (synergetic criteria of reliability of metalsusing the equation of relative strength turn into reality. The solution to this equation ofuniform plastic deformations of dmakes it possible to identify S , S , W , W values.? B K P C The initial experimental value of the hardness number may be used to calculate avariety of static and cyclical properties of steel and to identify the standard strength group and the approximate steel type counterpart.????????? ?????????? ??????? ?? ??????????? ? ??????????? ????????? ?????? ???????????? ??????????? ?? ????????????????? ????????? ????????? HRB c ????????????? ????????? ? HB.???????? ???????????? ????? ??????? ????????? HRB ? HB ?????????? = 60 [(?RB/703 + 1]. (1?????????? ?? (1 ???? ?????????????????? ?????????? ????????? HB ?????????? HB ????????.?? ?????? ????????????????-?????????????? ???????????? HRB-HB ????? ?????????? ????????? ????????????? ???????.

  14. Cloud cover typing from environmental satellite imagery. Discriminating cloud structure with Fast Fourier Transforms (FFT)

    Science.gov (United States)

    Logan, T. L.; Huning, J. R.; Glackin, D. L.

    1983-01-01

    The use of two dimensional Fast Fourier Transforms (FFTs) subjected to pattern recognition technology for the identification and classification of low altitude stratus cloud structure from Geostationary Operational Environmental Satellite (GOES) imagery was examined. The development of a scene independent pattern recognition methodology, unconstrained by conventional cloud morphological classifications was emphasized. A technique for extracting cloud shape, direction, and size attributes from GOES visual imagery was developed. These attributes were combined with two statistical attributes (cloud mean brightness, cloud standard deviation), and interrogated using unsupervised clustering amd maximum likelihood classification techniques. Results indicate that: (1) the key cloud discrimination attributes are mean brightness, direction, shape, and minimum size; (2) cloud structure can be differentiated at given pixel scales; (3) cloud type may be identifiable at coarser scales; (4) there are positive indications of scene independence which would permit development of a cloud signature bank; (5) edge enhancement of GOES imagery does not appreciably improve cloud classification over the use of raw data; and (6) the GOES imagery must be apodized before generation of FFTs.

  15. On the modular structure of the genus-one Type II superstring low energy expansion

    Science.gov (United States)

    D'Hoker, Eric; Green, Michael B.; Vanhove, Pierre

    2015-08-01

    The analytic contribution to the low energy expansion of Type II string amplitudes at genus-one is a power series in space-time derivatives with coefficients that are determined by integrals of modular functions over the complex structure modulus of the world-sheet torus. These modular functions are associated with world-sheet vacuum Feynman diagrams and given by multiple sums over the discrete momenta on the torus. In this paper we exhibit exact differential and algebraic relations for a certain infinite class of such modular functions by showing that they satisfy Laplace eigenvalue equations with inhomogeneous terms that are polynomial in non-holomorphic Eisenstein series. Furthermore, we argue that the set of modular functions that contribute to the coefficients of interactions up to order are linear sums of functions in this class and quadratic polynomials in Eisenstein series and odd Riemann zeta values. Integration over the complex structure results in coefficients of the low energy expansion that are rational numbers multiplying monomials in odd Riemann zeta values.

  16. Clathrate structure-type recognition: Application to hydrate nucleation and crystallisation

    Science.gov (United States)

    Lauricella, Marco; Meloni, Simone; Liang, Shuai; English, Niall J.; Kusalik, Peter G.; Ciccotti, Giovanni

    2015-06-01

    For clathrate-hydrate polymorphic structure-type (sI versus sII), geometric recognition criteria have been developed and validated. These are applied to the study of the rich interplay and development of both sI and sII motifs in a variety of hydrate-nucleation events for methane and H2S hydrate studied by direct and enhanced-sampling molecular dynamics (MD) simulations. In the case of nucleation of methane hydrate from enhanced-sampling simulation, we notice that already at the transition state, ˜80% of the enclathrated CH4 molecules are contained in a well-structured (sII) clathrate-like crystallite. For direct MD simulation of nucleation of H2S hydrate, some sI/sII polymorphic diversity was encountered, and it was found that a realistic dissipation of the nucleation energy (in view of non-equilibrium relaxation to either microcanonical (NVE) or isothermal-isobaric (NPT) distributions) is important to determine the relative propensity to form sI versus sII motifs.

  17. Structural insight into negative DNA supercoiling by DNA gyrase, a bacterial type 2A DNA topoisomerase

    Science.gov (United States)

    Papillon, Julie; Ménétret, Jean-François; Batisse, Claire; Hélye, Reynald; Schultz, Patrick; Potier, Noëlle; Lamour, Valérie

    2013-01-01

    Type 2A DNA topoisomerases (Topo2A) remodel DNA topology during replication, transcription and chromosome segregation. These multisubunit enzymes catalyze the transport of a double-stranded DNA through a transient break formed in another duplex. The bacterial DNA gyrase, a target for broad-spectrum antibiotics, is the sole Topo2A enzyme able to introduce negative supercoils. We reveal here for the first time the architecture of the full-length Thermus thermophilus DNA gyrase alone and in a cleavage complex with a 155 bp DNA duplex in the presence of the antibiotic ciprofloxacin, using cryo-electron microscopy. The structural organization of the subunits of the full-length DNA gyrase points to a central role of the ATPase domain acting like a ‘crossover trap’ that may help to sequester the DNA positive crossover before strand passage. Our structural data unveil how DNA is asymmetrically wrapped around the gyrase-specific C-terminal ?-pinwheel domains and guided to introduce negative supercoils through cooperativity between the ATPase and ?-pinwheel domains. The overall conformation of the drug-induced DNA binding–cleavage complex also suggests that ciprofloxacin traps a DNA pre-transport conformation. PMID:23804759

  18. Numerical model for the analysis of unbounded prestressed structures using the hybrid type finite element method

    International Nuclear Information System (INIS)

    Unbounded prestressed concrete has a growing importance all over the world and may be an useful technique for the structures involved in the construction of nuclear facilities. The absence of bonding means no strain compatibility so that equations developed for reinforced concrete are no longer valid. Practical estimates about the ultimate stress in the unbounded tendons may be obtained with empirical or numerical methods only. In order to contribute to the understanding on the behaviour of unbounded prestressed concrete members, a numerical model has been developed using a hybrid type finite element formulation for planar frame structures. Instead of short elements, as in the conventional finite element formulation, long elements may be used, improving computational efficiency. A further advantage is that the curvature variation within the element is obtained with higher accuracy if compared to the traditional formulation. This feature is important for unbounded tendons since its stresses depend on the whole member deformation. Second order effects in the planar frame are considered with either Updated or Partially Updated Lagrangian approaches. Instantaneous and time dependent behaviour as well as cyclic loads are considered too. Comparison with experimental results for prestressed concrete beams shows the adequacy of the proposed model. (authors)

  19. Prodrome of Paranoid Schizophrenia with Episodic Type of Course and Schizoaffective Structure of Manifest Episode

    Directory of Open Access Journals (Sweden)

    Alexander S. Bobrov

    2014-06-01

    Full Text Available Prodrome of paranoid schizophrenia with the episodic type of course (F20.1 and F20.2 according to ICD-10 and the schizoaffective structure of the episode was retrospectively studied. The pronounced and persistent affect, in particular depression in conjunction with hallucinations and/or delusions throughout the whole episode, served as the basis for an episode qualification as the schizoaffective structure. Diagnosis of schizophrenia was confirmed by the extremely low socio-demographic indicators at the time of the manifest episode, by the presence of catatonic or catatono-oneiroid symptoms in more than half of the patients, as well as an incongruence of hallucination plot and/or delusions against the dominant affect. In most cases, the affective symptoms were detected in clinical presentation of a prodrome and significantly more often in the form of depression, in comparison with bipolar and mixed affective disorders. Different clinical manifestations of negative symptoms were revealed in significantly more than half of the patients. The study showed that there is a significant frequency of negative manifestations in conjugation with depression in the prodrome.

  20. Estimation of seismic building structural types using multi-sensor remote sensing and machine learning techniques

    Science.gov (United States)

    Geiß, Christian; Aravena Pelizari, Patrick; Marconcini, Mattia; Sengara, Wayan; Edwards, Mark; Lakes, Tobia; Taubenböck, Hannes

    2015-06-01

    Detailed information about seismic building structural types (SBSTs) is crucial for accurate earthquake vulnerability and risk modeling as it reflects the main load-bearing structures of buildings and, thus, the behavior under seismic load. However, for numerous urban areas in earthquake prone regions this information is mostly outdated, unavailable, or simply not existent. To this purpose, we present an effective approach to estimate SBSTs by combining scarce in situ observations, multi-sensor remote sensing data and machine learning techniques. In particular, an approach is introduced, which deploys a sequential procedure comprising five main steps, namely calculation of features from remote sensing data, feature selection, outlier detection, generation of synthetic samples, and supervised classification under consideration of both Support Vector Machines and Random Forests. Experimental results obtained for a representative study area, including large parts of the city of Padang (Indonesia), assess the capabilities of the presented approach and confirm its great potential for a reliable area-wide estimation of SBSTs and an effective earthquake loss modeling based on remote sensing, which should be further explored in future research activities.

  1. The Russian oil industry re-structuration: towards the emergence of western type enterprises?

    International Nuclear Information System (INIS)

    The Russian oil industry has undergone fundamental changes since the collapse of the Soviet Empire and its bureaucratic administrative structure, dominated by its various Branch Ministries. The monopoly in the Soviet oil industry has now been replaced by a number of ''oil companies'', some of which are very powerful, the best known of them being Lukoil. These ''joint stock companies'' are the product of a reform aimed essentially at implanting, out of all the numerous organisational arrangements developed in the West, the model of the vertically integrated private firm. Beyond the legal reforms in the Russian oil industry sector, however, the nature of the organisational model that has actually emerged in Russia begs several questions. Many entities, which are complex and highly diversified, are involved in this industry. There are, of course, the many private structures in which the banks sometimes carry a considerable amount of weight. There are also some vertically integrated organisations, but the degree of integration is variable and their method of centralization is based on a specific form of economic logic. It should not be considered, however, that these actors are similar to capitalist-type private enterprises, whose behaviour is regulated by the demands of international competition. Reform of property rights has not been sufficient to create true private enterprise in Russia. (author)

  2. Structural and phase transformations in the low-temperature annealed amorphous “finemet”-type microwires

    Energy Technology Data Exchange (ETDEWEB)

    Tcherdyntsev, V.V., E-mail: vvch08@yandex.ru [National University of Science and Technology “MISIS”, Moscow 119049 (Russian Federation); Aleev, A.A. [SSC RF Institute for Theoretical and Experimental Physics, Moscow 117218 (Russian Federation); Churyukanova, M.N.; Kaloshkin, S.D. [National University of Science and Technology “MISIS”, Moscow 119049 (Russian Federation); Medvedeva, E.V. [Institute of Electrophysics, Ural Branch, Russian Academy of Sciences, Yekaterinburg 620016 (Russian Federation); Korchuganova, O.A. [SSC RF Institute for Theoretical and Experimental Physics, Moscow 117218 (Russian Federation); Zhukova, V. [Dpto. de Fns. Mater., UPV/EHU, San Sebastian 20018 (Spain); Zhukov, A.P. [Dpto. de Fns. Mater., UPV/EHU, San Sebastian 20018 (Spain); IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain)

    2014-02-15

    Highlights: • Structure and magnetic properties evolution at heating of amorphous microwires was studied. • Relaxation processes in the amorphous phase correlate with an increase in Curie temperature. • Curie temperature change can not be stabilized by a prolonged exposure at pre-crystallization temperatures. • Tomographic atom probe microscopy supports the formation of α-Fe phase precipitations enriched in Si. -- Abstract: Finemet-type glass-coated microwires with amorphous and nanocrystalline structure have been investigated. The relaxation and crystallization processes at heating of amorphous alloy have been studied by DSC method. We observed that the relaxation processes in the amorphous phase correlate with an increasing of the Curie temperature. Additionally a prolonged exposure of the samples below the crystallization temperatures does not stabilize the Curie temperature change. An investigation by the tomographic atom probe microscopy supports the formation of precipitations, probably α-Fe phase, as a result of low-temperature annealing (400 °C, 5 min). We found that the observed nano-sized areas were enriched in silicon.

  3. Fast Solid-State Li Ion Conducting Garnet-Type Structure Metal Oxides for Energy Storage.

    Science.gov (United States)

    Thangadurai, Venkataraman; Pinzaru, Dana; Narayanan, Sumaletha; Baral, Ashok Kumar

    2015-01-15

    Lithium ion batteries are the most promising energy storage system on the market today; however, safety issues associated with the use of flammable organic polymer-based electrolytes with poor electrochemical and chemical stabilities prevent this technology from reaching maturity. Solid lithium ion electrolytes (SLIEs) are being considered as potential replacements for the organic electrolytes to develop all-solid-state Li ion batteries. Out of the recently discovered SLIEs, the garnet-related structured Li-stuffed metal oxides are the most promising electrolytes due to their high total (bulk + grain boundary) Li ion conductivity, high electrochemical stability window (?6 V versus Li(+)/Li at room temperature), and chemical stability against reaction with an elemental Li anode and high-voltage metal oxide Li cathodes. This Perspective discusses the structural-chemical composition-ionic conductivity relationship of Li-stuffed garnets, followed by a discussion on the Li ion conduction mechanism, as well as the electrochemical and chemical stability of these materials. The performance of a number of all-solid-state batteries employing garnet-type Li ion electrolytes is also discussed. PMID:26263465

  4. A COMPARISON OF TWO THERMAL INSULATION AND STRUCTURAL MATERIALS FOR USE IN TYPE B PACKAGINGS

    Energy Technology Data Exchange (ETDEWEB)

    Blanton, P.; Eberl, K.

    2010-07-16

    This paper presents the summary of design features and test results of two Type B Shipping Package prototype configurations comprising different insulating materials developed by the Savannah River National Laboratory (SRNL) for the Department of Energy. The materials evaluated, a closed-cell polyurethane foam and a vacuformed ceramic fiber material, were selected to provide adequate structural protection to the package containment vessel during Normal Conditions of Transport (NCT) and Hypothetical Accident Condition (HAC) events and to provide thermal protection during the HAC fire. Polyurethane foam has been used in shipping package designs for many years because of the stiffness it provides to the structure and because of the thermal protection it provides during fire scenarios. This comparison describes how ceramic fiber material offers an alternative to the polyurethane foam in a specific overpack design. Because of the high operating temperature ({approx}2,300 F) of the ceramic material, it allows for contents with higher heat loads to be shipped than is possible with polyurethane foam. Methods of manufacturing and design considerations using the two materials will be addressed.

  5. Superconductivity in LaBi3 with AuCu3-type structure

    Science.gov (United States)

    Kinjo, Tatsuya; Kajino, Saori; Nishio, Taichiro; Kawashima, Kenji; Yanagi, Yousuke; Hase, Izumi; Yanagisawa, Takashi; Ishida, Shigeyuki; Kito, Hijiri; Takeshita, Nao; Oka, Kunihiko; Eisaki, Hiroshi; Yoshida, Yoshiyuki; Iyo, Akira

    2016-03-01

    We succeeded in synthesizing a new intermetallic compound with a AuCu3-type structure, LaBi3, by utilizing a high-pressure technique. Reacting Bi and LaBi at 450 °C under a pressure of 3.4 GPa resulted in the crystallization of LaBi3 with an a-axis lattice parameter of 4.99\\+/- 0.02\\mathring{{A}} . Sharp superconducting transitions were observed in both its magnetic susceptibility and electrical resistivity at 7.3–7.4 K. The upper critical field {? }0{H}{{c}2}(0) and Ginzburg–Landau coherence length ? 0 were estimated to be 1.70 T and 139 Å, respectively. The superconducting transition temperature T c was found to decrease linearly with increasing applied pressure with a slope of ?0.26 K GPa?1. Band structure calculations indicated that this compound has a multiband nature and that its Fermi energy is located exactly at one of the peak density of states.

  6. Durability improvement assessment in different high strength bacterial structural concrete grades against different types of acids

    Indian Academy of Sciences (India)

    Ramin Andalib; M Zaimi Abd Majid; A Keyvanfar; Amirreza Talaiekhozan; Mohd Warid Hussin; A Shafaghat; Rosli Mohd Zin; Chew Tin Lee; Mohammad Ali Fulazzaky; Hasrul Haidar Ismail

    2014-12-01

    This paper provides an insight into a new biotechnological method based on calcite precipitation for achieving high strength bio-concrete durability. It is very clear that mineral precipitation has the potential to enhance construction material resistance towards degradation procedures. The appropriate microbial cell concentration (30 * 105 cells/ml) was introduced onto different structural concrete grades (40, 45 and 50 MPa) by mixing water. In order to study the durability of structural concrete against aggressive agents, specimens were immersed in different types of acids solution (5% H2SO4 and HCl) to compare their effects on 60th, 90th and 120th day. In general, sulphuric acid and hydrochloric acid are known to be the most aggressive natural threats from industrial waters which can penetrate concrete to transfer the soluble calcium salts away from the cement matrix. The experimental results demonstrated that bio-concrete has less weight and strength losses when compared to the ordinary Portland cement concrete without microorganism. It was also found that maximum compressive strength and weight loss occurred during H2SO4 acid immersion as compared to HCl immersion. The density and uniformity of bio-concrete were examined using ultrasonic pulse velocity (UPV) test. Microstructure chemical analysis was also quantified by energy dispersive spectrometer (EDS) to justify the durability improvement in bacterial concrete. It was observed that less sulphur and chloride were noticed in bacterial concrete against H2SO4 and HCl, respectively in comparison to the ordinary Portland cement concrete due to calcite deposition.

  7. Structural and Magnetic Properties of Type-M Barium Ferrite - Thermoplastic Natural Rubber Nano composites

    International Nuclear Information System (INIS)

    Structural and magnetic properties of type-M barium ferrite (BaFe12O19) nanoparticles (? 20 nm) embedded in non-magnetic thermoplastic natural rubber (TPNR) matrices were investigated. The TPNR matrices were prepared from high density polyethylene (HDPE) and natural rubber (NR) in the weight ratios of 80:20 and 60:40, respectively, with 10 wt % of NR in the form of liquid natural rubber (LNR) which act as a comparabilities. BaFe12O19 - filled nano composites with 2 - 12 wt % BaFe12O19 ferrite were prepared using a melt- blending technique. Magnetic hysteresis was measured using a vibrating sample magnetometer (VSM) in a maximum field of 10 kOe at room temperature (25 degree Celsius). The saturation magnetisation (MS), remanence (MR) and coercivity (Hc) were derived from the hysteresis loops. The results show that the structural and magnetic properties of nano composites depend on both the ferrite content and the composition of the natural rubber or plastic in the nano composites. All the nano composites exhibit an exchange bias-like phenomenon resulting from the exchange coupling of spins at the interface between the core ferrimagnetic region and the disordered surface region of the nanoparticles. (author)

  8. The Russian oil industry re-structuration: towards the emergence of western type enterprises?

    Energy Technology Data Exchange (ETDEWEB)

    Locatelli, C

    1999-01-01

    The Russian oil industry has undergone fundamental changes since the collapse of the Soviet Empire and its bureaucratic administrative structure, dominated by its various Branch Ministries. The monopoly in the Soviet oil industry has now been replaced by a number of ''oil companies'', some of which are very powerful, the best known of them being Lukoil. These ''joint stock companies'' are the product of a reform aimed essentially at implanting, out of all the numerous organisational arrangements developed in the West, the model of the vertically integrated private firm. Beyond the legal reforms in the Russian oil industry sector, however, the nature of the organisational model that has actually emerged in Russia begs several questions. Many entities, which are complex and highly diversified, are involved in this industry. There are, of course, the many private structures in which the banks sometimes carry a considerable amount of weight. There are also some vertically integrated organisations, but the degree of integration is variable and their method of centralization is based on a specific form of economic logic. It should not be considered, however, that these actors are similar to capitalist-type private enterprises, whose behaviour is regulated by the demands of international competition. Reform of property rights has not been sufficient to create true private enterprise in Russia. (author)

  9. Electrical and structural properties of p -type nanocrystalline silicon grown by LEPECVD for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Micard, Gabriel; Hahn, Giso; Terheiden, Barbara [Department of Physics, Faculty of Sciences, University of Konstanz (Germany); Chrastina, Daniel; Isella, Giovanni; Moiseev, Tamara [L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo Regionale di Como (Italy); Cavalcoli, Daniela; Cavallini, Anna [Department of Physics, University of Bologna (Italy); Binetti, Simona; Acciarri, Maurizio; Le Donne, Alessia [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Milano (Italy); Texier, Michael [Institut Materiaux, Microelectronique, Nanosciences de Provence (IM2NP UMR 6242) Fac. Sciences et Techniques de Saint Jerome, Marseille (France); Pichaud, Bernard [Institut Materiaux, Microelectronique, Nanosciences de Provence (IM2NP UMR 6242) Fac. Sciences et Techniques de Saint Jerome, Marseille (France)

    2010-04-15

    p-doped hydrogenated nanocrystalline silicon (p-nc-Si:H) is one of the most critical layers in thin film silicon solar cells. LEPECVD is a new technique for the growth of nc-Si at high growth rate without compromising the layer quality, using a dense but low energy plasma. Thin p-nc-Si:H layers are grown on glass and ZnO:Al coated glass and their structural and electrical properties are investigated as a function of the silane dilution (d) and of the doping ratio (DR). The influence of the substrate on the structural properties is investigated and discussed. The incubation layer is clearly observed on both substrate types and its thickness is estimated. LEPECVD distinguishes itself from other high growth rate methods by a very low impurity distribution coefficient to obtain a comparable conductivity and boron density. The conduction path is shown to be dependent on the density of boron in the layer while a significant decrease of conductivity at high DR is not observed in the studied range (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Preparation and crystal structure of the Er1Si2-x(vacancy)x compound, derivative of the AlB2 type structure

    International Nuclear Information System (INIS)

    The rare earth silicides are of great interest in applications to semiconductor technolgy and form the subject of studies aiming at a better understanding of their physical properties in relation with their structure and composition. A systematic study of the RSi2-x compounds, which crystallize in three main structure types ThSi2, GdSi2, AlB2 led us to find an orthorhombic superstructure of the hexagonal ErSi2-x (AlB2-type) structure. This superstructure is caused by a particular arrangement of the vacancies in the silicon sub-lattice

  11. Structural and electrochemical characterisation of [Pd(salen)]-type conducting polymer films

    Energy Technology Data Exchange (ETDEWEB)

    Fonseca, J. [REQUIMTE, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); Tedim, J. [Department of Chemistry, University of Leicester, Leicester LE1 7 RH (United Kingdom); Biernacki, K.; Magalhaes, A.L. [REQUIMTE, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); Gurman, S.J. [Department of Physics, University of Leicester, Leicester LE1 7 RH (United Kingdom); Freire, C., E-mail: acfreire@fc.up.p [REQUIMTE, Departamento de Quimica e Bioquimica, Faculdade de Ciencias, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto (Portugal); Hillman, A.R., E-mail: arh7@le.ac.u [Department of Chemistry, University of Leicester, Leicester LE1 7 RH (United Kingdom)

    2010-11-01

    The oxidative polymerisation of four structurally-related [Pd(salen)] complexes and characterisation of the resulting polymeric films by cyclic voltammetry (CV), UV-visible transmission spectroscopy, X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) is reported. The voltammetric technique gives insight into the electrochemical properties of the polymeric films whereas UV-visible spectroscopy is used to characterise the electronic structure of Pd electroactive films, of particular relevance to the type of charge carriers. X-ray techniques (supported by density functional theory, DFT) provide information related to composition and structural features of [Pd(salen)] precursors and the resulting polymers. Characterisation of poly[Pd(salen)] films shows that the electrochemical response of these supramolecular systems is ligand-based and dependent upon substituents in the diimine bridge and aldehyde moieties. XAS measurements near the Pd K-edge demonstrate that polymerisation of the Pd complexes does not change the coordination sphere of the Pd centre; this is consistent with the coupling of monomers units via phenyl rings. As further evidence of ligand-based electrochemical responses, polymer doping does not impart any changes at the Pd centre or its coordination sphere. Compositional analysis by XPS confirms that C: Pd, N: Pd and O: Pd surface atomic ratios do not change significantly from monomer to undoped or doped polymer, except for small variations associated with incorporation of electrolyte and solvent upon polymerisation and polymer oxidation. Overall, the data provide a picture of a polyaromatic delocalised electroactive system, in which the metal atom plays a templating (rather than electroactive) role.

  12. The structure of TeV-bright shell-type supernova remnants

    Science.gov (United States)

    Yang, Chuyuan; Liu, Siming; Fang, Jun; Li, Hui

    2015-01-01

    Aims: Two-dimensional magnetohydrodynamic (MHD) simulations are used to model the emission properties of TeV-bright shell-type supernova remnants (SNRs) and to explore their nature. Methods: In the leptonic scenario for the TeV emission, the ?-ray emission is produced via inverse Compton scattering of background soft photons by high-energy electrons accelerated by the shocks of the SNRs. In a previous paper, we showed that since the energy densities of the cosmic microwave background radiation and that of the IR/optical background photons are much higher than that of the photons produced by the same high-energy electrons via the synchrotron process, the observed correlation between X-ray and TeV brightness of SNR RX J1713.7-3946 can be readily explained with the assumption that the energy density of relativistic electrons is proportional to that of the magnetic field. The TeV emissivity is therefore proportional to the magnetic field energy density and MHD simulations can be used to model the TeV structure of such remnants directly. Two-dimensional MHD simulations for SNRs are then performed under the assumption that the ambient interstellar medium is turbulent with the magnetic field and density fluctuations, following a Kolmogorov-like power-law spectrum. Results: (1) As expected, these simulations confirm early 1D and 2D modelings of these sources, namely the hydrodynamical evolution of the shock waves and amplification of magnetic field by Rayleigh-Taylor convective flows and by shocks propagating in a turbulent medium; (2) we reproduce rather complex morphological structure for ?-rays, for example, the bright thin rim and significant asymmetry, suggesting intrinsic variations of the source morphology not related to the structure of the progenitor and environment; and (3) the observed radial profile of several remnants are well reproduced with an ambient medium density of 0.1-1 cm-3. An even lower ambient density leads to a sharper drop of the TeV brightness with radius than what is observed near the outer edge of these remnants. Conclusions: In a turbulent background medium, we can reproduce the observed characteristics of several shell-type TeV SNRs with reasonable parameters except for a higher ambient density than that inferred from X-ray observations.

  13. Itinerant type many-body theories for photo-induced structural phase transitions

    Science.gov (United States)

    Nasu, Keiichiro

    2004-09-01

    Itinerant type quantum many-body theories for photo-induced structural phase transitions (PSPTs) are reviewed in close connection with various recent experimental results related to this new optical phenomenon. There are two key concepts: the hidden multi-stability of the ground state, and the proliferations of optically excited states. Taking the ionic (I) rarr neutral (N) phase transition in the organic charge transfer (CT) crystal, TTF-CA, as a typical example for this type of transition, we, at first, theoretically show an adiabatic path which starts from CT excitons in the I-phase, but finally reaches an N-domain with a macroscopic size. In connection with this I-N transition, the concept of the initial condition sensitivity is also developed so as to clarify experimentally observed nonlinear characteristics of this material. In the next, using a more simplified model for the many-exciton system, we theoretically study the early time quantum dynamics of the exciton proliferation, which finally results in the formation of a domain with a large number of excitons. For this purpose, we derive a stepwise iterative equation to describe the exciton proliferation, and clarify the origin of the initial condition sensitivity. Possible differences between a photo-induced nonequilibrium phase and an equilibrium phase at high temperatures are also clarified from general and conceptional points of view, in connection with recent experiments on the photo-induced phase transition in an organo-metallic complex crystal. It will be shown that the photo-induced phase can make a new interaction appear as a broken symmetry only in this phase, even when this interaction is almost completely hidden in all the equilibrium phases, such as the ground state and other high-temperature phases. The relation between the photo-induced nonequilibrium phase and the hysteresis induced nonequilibrium one is also qualitatively discussed. We will be concerned with a macroscopic parity violation and a ferro- (or super-para-) electricity, induced by a photogenerated electron in the perovskite type quantum dielectric SrTiO3. The photogenerated electron in the 3d band of Ti is assumed to couple weakly, but quadratically, with soft-anharmonic T1u phonons, and strongly but linearly to the breathing (A1g) type high energy phonons. These two types of electron-phonon coupling result in two types of polarons, a super-para-electric (SPE) large polaron with a quasi-global parity violation, and an off-centre type self-trapped polaron with only a local parity violation. This SPE large polaron, being equal to a charged and conductive ferroelectric domain, greatly enhances both the quasi-static electric susceptibility and the electronic conductivity. We also briefly review recent successes to observe the PSPTs more directly by using x-ray measurements.

  14. The influence of dendritic structure stereology on frictional wear of cast steel Cr-Mo-V-Ni-Cu type

    International Nuclear Information System (INIS)

    The paper presents quantitative and qualitative influence of stereological structure parameters on abrasive wear of alloy cast steel Cr-Mo-V-Ni-Cu type at temperature of 293 K and 773 K. The dependence between frictional wear and structural parameters - i.e.: interdendritic space; mean linear size, relative volume and dispersion index of the dendrites - has been estimated. (author)

  15. Monazite-type ceramics for conditioning of minor actinides. Structural characterization and properties

    Energy Technology Data Exchange (ETDEWEB)

    Babelot, Carole

    2013-07-01

    The minor actinides (MA) neptunium, americium, and curium are mainly responsible for the long-term radiotoxicity of the High Active Waste (HAW) generated during the nuclear power operation. If these long-lived radionuclides are removed from the HAW by partitioning and converted by neutron fission (transmutation) into shorter-lived or stable elements, the remaining waste loses most of its long-term radiotoxicity. Thus, partitioning and transmutation (P and T) are considered as attractive options for reducing the burden on geological disposals. As an alternative, these separated MA can also be conditioned (P and C strategy) in specifically adapted ceramics to ensure their safe final disposal over long periods. At the moment, spent fuel elements are foreseen either for direct disposal in deep geological repositories or for reprocessing. The highly active liquid waste that is produced during reprocessing is conditioned industrially using a vitrification process before final disposal. Although the widely used borosilicate glasses meet most of the specifications needed, ceramic host matrices appear to be even more suitable in terms of resistance to corrosion. The development of new materials based on tailor-made highly specific ceramics with extremely stable behavior would make it possible to improve the final storage of long-lived high-level radiotoxic waste. In the framework of this PhD research project, monazite-type ceramics were chosen as promising host matrices for the conditioning of trivalent actinides. The focus on the monazite-type ceramics is justified by their properties such as high chemical durability. REPO{sub 4} ceramics are named monazite for RE = La - Gd (monoclinic symmetry) and xenotime for RE = Tb - Lu and Y (tetragonal symmetry). The objective of this study is to contribute to the understanding of the alteration behavior of such ceramics under the repository conditions. REPO{sub 4} (with RE = La, Eu) is prepared by hydrothermal synthesis at 200 C. Structural and morphological characteristics (using X-ray diffraction (XRD) and scanning electron microscope (SEM)) combined with physical and thermal properties of samples (using thermogravimetry, differential scanning calorimetry (TG-DSC) and dilatometry) are realized in order to study the behavior of monazite-type powder and pellets. The access to short-range-order spectroscopy (time resolved laser fluorescence spectroscopy (TRLFS) and extended X-ray absorption fine structure (EXAFS)) permits to understand the structure of ceramic waste forms at the molecular level. La-monazite matrices being doped with Eu (III) (as a non-radioactive chemical homologue for Am (III)) and Cm (III), TRLFS is used to explore the local structural environment of Eu and Cm within the monazite crystal structure. Eu (III) and Cm (III) are substituted on the La site of LaPO{sub 4}. The single site of Cm (III) is found in four slightly different environments which is assumed to be due to a difference in the four La sites within a LaPO4 unit cell. Structural parameters of the Eu (III) species were also analyzed by EXAFS. The nearest neighbors of Eu (III) are modeled as 9.5 oxygen atoms (N{sub O1} = 4 at r(EuO1) = 2.37 Aa, N{sub O2} = 4 at r(Eu-O2) = 2.53 Aa, and N{sub O3} = 1.5 at r(Eu-O3) = 2.83 Aa). An essential parameter that describes the stability of the host phases is their dissolution rate obtained under conditions of relevance for final repositories. In this context, a set-up is developed and tested on crushed pellets. Normalized weight losses of lanthanumphosphates and europium-doped lanthanum-phosphates, measured in acidic media at 90 C, are interpreted and compared against the previous findings from the literature. The normalized dissolution rate for La and Eu within (La, Eu)PO{sub 4} is between 1.10{sup -5} and 1.10{sup -4} g.m{sup -2}.d{sup -1}, whereas the rate of Na, Cs and Sr in phosphate glass at room temperature in deionized water is about 1.10{sup -2} g.m{sup -2}.d{sup -1}. Another essential parameter is their resistance to radiation. The damage created by the recoils accompanying alpha-decay can be simulated on ceramic matrices. Preliminary experiments are realized by means of ion bombardment. Kr{sup 2+} ions are implanted in La-monazite-type pellets, and the effects on the LaPO{sub 4} structure resulting from the Raman spectroscopy are poor. On a laboratory scale, the promising characteristics of the monazite mineral are found again in the synthetic phosphate. In particular, the doping of actinide surrogates is successful and the corrosion tests under repository conditions show a good resistance of the samples. The results achieved in this work confirm that among other favorable ceramics (e.g. pyrochlore) the ''monazite-route'' has to be further pursued regarding the research on the conditioning of MA.

  16. Monazite-type ceramics for conditioning of minor actinides. Structural characterization and properties

    International Nuclear Information System (INIS)

    The minor actinides (MA) neptunium, americium, and curium are mainly responsible for the long-term radiotoxicity of the High Active Waste (HAW) generated during the nuclear power operation. If these long-lived radionuclides are removed from the HAW by partitioning and converted by neutron fission (transmutation) into shorter-lived or stable elements, the remaining waste loses most of its long-term radiotoxicity. Thus, partitioning and transmutation (P and T) are considered as attractive options for reducing the burden on geological disposals. As an alternative, these separated MA can also be conditioned (P and C strategy) in specifically adapted ceramics to ensure their safe final disposal over long periods. At the moment, spent fuel elements are foreseen either for direct disposal in deep geological repositories or for reprocessing. The highly active liquid waste that is produced during reprocessing is conditioned industrially using a vitrification process before final disposal. Although the widely used borosilicate glasses meet most of the specifications needed, ceramic host matrices appear to be even more suitable in terms of resistance to corrosion. The development of new materials based on tailor-made highly specific ceramics with extremely stable behavior would make it possible to improve the final storage of long-lived high-level radiotoxic waste. In the framework of this PhD research project, monazite-type ceramics were chosen as promising host matrices for the conditioning of trivalent actinides. The focus on the monazite-type ceramics is justified by their properties such as high chemical durability. REPO4 ceramics are named monazite for RE = La - Gd (monoclinic symmetry) and xenotime for RE = Tb - Lu and Y (tetragonal symmetry). The objective of this study is to contribute to the understanding of the alteration behavior of such ceramics under the repository conditions. REPO4 (with RE = La, Eu) is prepared by hydrothermal synthesis at 200 C. Structural and morphological characteristics (using X-ray diffraction (XRD) and scanning electron microscope (SEM)) combined with physical and thermal properties of samples (using thermogravimetry, differential scanning calorimetry (TG-DSC) and dilatometry) are realized in order to study the behavior of monazite-type powder and pellets. The access to short-range-order spectroscopy (time resolved laser fluorescence spectroscopy (TRLFS) and extended X-ray absorption fine structure (EXAFS)) permits to understand the structure of ceramic waste forms at the molecular level. La-monazite matrices being doped with Eu (III) (as a non-radioactive chemical homologue for Am (III)) and Cm (III), TRLFS is used to explore the local structural environment of Eu and Cm within the monazite crystal structure. Eu (III) and Cm (III) are substituted on the La site of LaPO4. The single site of Cm (III) is found in four slightly different environments which is assumed to be due to a difference in the four La sites within a LaPO4 unit cell. Structural parameters of the Eu (III) species were also analyzed by EXAFS. The nearest neighbors of Eu (III) are modeled as 9.5 oxygen atoms (NO1 = 4 at r(EuO1) = 2.37 Aa, NO2 = 4 at r(Eu-O2) = 2.53 Aa, and NO3 = 1.5 at r(Eu-O3) = 2.83 Aa). An essential parameter that describes the stability of the host phases is their dissolution rate obtained under conditions of relevance for final repositories. In this context, a set-up is developed and tested on crushed pellets. Normalized weight losses of lanthanumphosphates and europium-doped lanthanum-phosphates, measured in acidic media at 90 C, are interpreted and compared against the previous findings from the literature. The normalized dissolution rate for La and Eu within (La, Eu)PO4 is between 1.10-5 and 1.10-4 g.m-2.d-1, whereas the rate of Na, Cs and Sr in phosphate glass at room temperature in deionized water is about 1.10-2 g.m-2.d-1. Another essential parameter is their resistance to radiation. The damage created by the recoils accompanying alpha-decay can be simulated on ceramic matrices. Preliminary experiments are realized by means of ion bombardment. Kr2+ ions are implanted in La-monazite-type pellets, and the effects on the LaPO4 structure resulting from the Raman spectroscopy are poor. On a laboratory scale, the promising characteristics of the monazite mineral are found again in the synthetic phosphate. In particular, the doping of actinide surrogates is successful and the corrosion tests under repository conditions show a good resistance of the samples. The results achieved in this work confirm that among other favorable ceramics (e.g. pyrochlore) the ''monazite-route'' has to be further pursued regarding the research on the conditioning of MA.

  17. Structural design studies on a large pool type SFR of 1200MWe

    International Nuclear Information System (INIS)

    An economic improvement is a hot issue as one of the Gen IV nuclear plant goals. To secure economic competitiveness of a SFR compared to a pressurized water reactor, several structural design concepts are adapted in without loosing the reactor safety level. One is the increase of the plant capacity with the minimum number of component and loop, which leads the reduction of the plant maintenance, repair, and construction costs by a large-size scale effect. Another is the simple system arrangement, compact reactor size for only two loop system for a 1200MWe capacity of a pool type SFR, and the minimization of IHTS piping length through the properly locating the SG and secondary pump. Several researches are also studied to attain the economic improvement target of the NSSS in structural point of view; for example, an integrated concept of a refueling machine and inspection device with a long waveguide sensor for reactor internals. Fig.1 shows the reactor internals and components arrangement in reactor vessel. The outer diameter of the reactor vessel is 14.5m, which is very compact size compared to other designs, and 0.05m in thickness. It can accommodate the maximum core size of 7.9m. With the internal arrangement, the refueling availability of core assemblies was confirmed, and 36 control rods are supported and guided by upper internal structures. The material of reactor vessel and internal structure is a Type 316 stainless steel. The primary system consists of 4 sets of primary pump, IHX, and DHX in reactor vessel. The component size is not much larger than the KALIMER-600 design because the numbers of components was increased. The reactor vessel's diameter is relatively so small that the minimum space between the components is 55cm, which may not be enough for equipment maintenance. The NSSS has two intermediate heat transport loops. The each of IHTS loops outside of the reactor vessel has 2 mechanical type pumps and 2 SGs. The fabricability of the piping and elbows of the large piping diameter was investigated for realizing this system. The piping diameters for the hot and cold legs of 80 cm and 110cm respectively are within the feasible fabrication range through the both ways of forged pipe and seamless pipe. The piping length of each loop is relatively long about 180m because of the inverse U shape piping layout adapted to the preventing the pressure propagation to the reactor vessel when a sodium-water reaction accident occurs in SG upper tube. Since this long piping layout increases the maintenance cost, the shortening of the piping total length would be necessary by properly sacrificing over-excessive safety design level. The pipe material of a Mod.9Cr-1Mo can shorten the piping length about 60m compared to stainless steel, which has also a higher mechanical strength and a low thermal expansion. This has an advantage for obtaining a simple layout of IHTS piping subjected to a high temperature environment. The two-loop system is also advantageous to a compact building size because the numbers of components can be minimized, and the total piping length could be shortened. The height of the SG is about 37.4 m. The SG tube is a double-wall straight type to reduce the possibility of the water injection to the sodium side. Two new design strategies are adapted for the economic improvement of the NSSS in structural point of view. One is an integrated component of a refueling machine and an in- service inspection (ISI) tool with a long life waveguide sensor for reactor internals. This concept will shorten the overall period of about 2 days through the reduction of in-service inspection time of Rx internals.The other is a LBB technology application for IHTS piping and RV, which will reduce the construction cost because of the unnecessary of a large scale protection facilities against to sodium leak accidents. The component arrangement and reactor structural sizing for two loop systems for a 1200MWe capacity of a SFR are suggested with several structural design improved concepts to attain an economic improvement of a large s

  18. Structure and magnetic properties of new bcc A2-type based superstructures in R-Fe-B systems

    International Nuclear Information System (INIS)

    Two new bcc 3-dimensional superstructures based on the A2-type structure having lattice parameters an=na0 with n=2, 4 and a0=lattice parameter of the A2-type basic structure, have been obtained either by quenching the melts at moderate cooling rates or by crystallizing glasses of alloys close to compositions R2-xFe14B (0< x?1, R=rare earth metal or Y). These bcc compounds are soft magnetic with Curie temperatures in the range 400 to 600 K. Composite hard magnetic exchange-spring type magnets are obtained upon their decomposition at about 1000 K. (orig.)

  19. The Electronic Structure of CdSe/CdS Core/Shell Seeded Nanorods: Type-I or Quasi-Type-II?

    OpenAIRE

    Eshet, Hagai; Grünwald, Michael; Rabani, Eran

    2013-01-01

    The electronic structure of CdSe/CdS core/shell seeded nanorods of experimentally relevant size is studied using a combination of molecular dynamics and semiempirical pseudopotential techniques, with the aim to address the transition from type-I to a quasi-type-II band alignment. The hole is found to be localized in the core region regardless of its size. The overlap of the electron density with the core region depends markedly on the size of the CdSe core: For small cores, we observe little ...

  20. Electronic structure and thermoelectric properties of n- and p-type SnSe from first principles calculations

    OpenAIRE

    Kutorasinski, K.; Wiendlocha, B.; Kaprzyk, S.; Tobola, J.

    2015-01-01

    We present results of electronic band structure, Fermi surface and electron transport properties calculations in orthorhombic $n$- and $p$-type SnSe, applying Korringa-Kohn-Rostoker method and Boltzmann transport approach. The analysis accounted for temperature effect on crystallographic parameters in $Pnma$ structure as well as the phase transition to $CmCm$ structure at $T_c\\sim 807 $K. Remarkable modifications of conduction and valence bands were notified upon varying cry...

  1. Non-degenerate homogeneous $\\epsilon$-K\\"ahler and $\\epsilon$-quaternion K\\"ahler structures of linear type

    OpenAIRE

    Luján, Ignacio; Swann, Andrew

    2013-01-01

    We study the class of non-degenerate homogeneous structures of linear type in the pseudo-K\\"ahler, para-K\\"ahler, pseudo-quaternion K\\"ahler and para-quaternion K\\"ahler cases. We show that these structures characterize spaces of constant holomorphic, para-holomorphic, quaternion and para-quaternion sectional curvature respectively. In addition the corresponding homogeneous models are computed, exhibiting the relation between these kind of structures and the incompleteness of the metric.

  2. Singularity Structures in Coulomb-Type Potentials in Two-Body Dirac Equations of Constraint Dynamics

    International Nuclear Information System (INIS)

    Two-body Dirac equations (TBDE) of Dirac's relativistic constraint dynamics have been successfully applied to obtain a covariant nonperturbative description of QED and QCD bound states. Coulomb-type potentials in these applications lead naively in other approaches to singular relativistic corrections at short distances that require the introduction of either perturbative treatments or smoothing parameters. We examine the corresponding singular structures in the effective potentials of the relativistic Schroedinger equation obtained from the Pauli reduction of the TBDE. We find that the relativistic Schroedinger equation leads in fact to well-behaved wave function solutions when the full potential and couplings of the system are taken into account. The most unusual case is the coupled triplet system with S=1 and L={(J-1),(J+1)}. Without the inclusion of the tensor coupling, the effective S-state potential would become attractively singular. We show how including the tensor coupling is essential in order that the wave functions be well-behaved at short distances. For example, the S-state wave function becomes simply proportional to the D-state wave function and dips sharply to zero at the origin, unlike the usual S-state wave functions. Furthermore, this behavior is similar in both QED and QCD, independent of the asymptotic freedom behavior of the assumed QCD vector potential. Light- and heavy-quark meson states can be described well by using a simplified linear-plus-Coulomb-type QCD potential apportioned appropriately between world scalar and vector potentials. We use this potential to exhibit explicitly the origin of the large pi-rho splitting and effective chiral symmetry breaking. The TBDE formalism developed here may be used to study quarkonia in quark-gluon plasma environments

  3. Structural analysis of a specialized type III secretion system peptidoglycan-cleaving enzyme.

    Science.gov (United States)

    Burkinshaw, Brianne J; Deng, Wanyin; Lameignère, Emilie; Wasney, Gregory A; Zhu, Haizhong; Worrall, Liam J; Finlay, B Brett; Strynadka, Natalie C J

    2015-04-17

    The Gram-negative bacterium enteropathogenic Escherichia coli uses a syringe-like type III secretion system (T3SS) to inject virulence or "effector" proteins into the cytoplasm of host intestinal epithelial cells. To assemble, the T3SS must traverse both bacterial membranes, as well as the peptidoglycan layer. Peptidoglycan is made of repeating N-acetylmuramic acid and N-acetylglucosamine disaccharides cross-linked by pentapeptides to form a tight mesh barrier. Assembly of many macromolecular machines requires a dedicated peptidoglycan lytic enzyme (PG-lytic enzyme) to locally clear peptidoglycan. Here we have solved the first structure of a T3SS-associated PG-lytic enzyme, EtgA from enteropathogenic E. coli. Unexpectedly, the active site of EtgA has features in common with both lytic transglycosylases and hen egg white lysozyme. Most notably, the ?-hairpin region resembles that of lysozyme and contains an aspartate that aligns with lysozyme Asp-52 (a residue critical for catalysis), a conservation not observed in other previously characterized lytic transglycosylase families to which the conserved T3SS enzymes had been presumed to belong. Mutation of the EtgA catalytic glutamate, Glu-42, conserved across lytic transglycosylases and hen egg white lysozyme, and this differentiating aspartate diminishes type III secretion in vivo, supporting its essential role in clearing the peptidoglycan for T3SS assembly. Finally, we show that EtgA forms a 1:1 complex with the building block of the polymerized T3SS inner rod component, EscI, and that this interaction enhances PG-lytic activity of EtgA in vitro, collectively providing the necessary strict localization and regulation of the lytic activity to prevent overall cell lysis. PMID:25678709

  4. Effect of annealing temperature on the structural, photoluminescence and magnetic properties of sol-gel derived Magnetoplumbite-type (M-type) hexagonal strontium ferrite

    International Nuclear Information System (INIS)

    Magnetoplumbite-type (M-type) hexagonal strontium ferrite particles were synthesized via sol-gel technique employing ethylene glycol as the gel precursor at two different calcination temperatures (800 and 1000 deg. C). Structural properties were systematically investigated via X-ray diffraction (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy (HRTEM), energy dispersive spectroscopy (EDS), thermogravimetric analysis (TGA), photoluminescence spectrophotometry and superconducting quantum interference device magnetometer. XRD results showed that the sample synthesized at 1000 deg. C was of single-phase with a space group of P63/mmc and lattice cell parameter values of a=5.882 A and c=23.048 A. EDS confirmed the composition of strontium ferrite calcined at 1000 deg. C being mainly of M-type SrFe12O19 with HRTEM micrographs confirming the ferrites exhibiting M-type long range ordering along the c-axis of the crystal structure. The photoluminescence (PL) property of strontium ferrite was examined at excitation wavelengths of 260 and 270 nm with significant PL emission peaks centered at 350 nm being detected. Strontium ferrite annealed at higher temperature (1000 deg. C) was found to have grown into larger particle size, having higher content of oxygen vacancies and exhibited 83-85% more intense PL. Both the as-prepared strontium ferrites exhibited significant oxygen vacancies defect structures, which were verified via TGA. Higher calcination temperature turned strontium ferrite into a softer ferrite. - Highlights: ? High annealing temperature produced M-type ferrite with higher oxygen vacancies. ? Photoluminescence intensity is proportional to the existence of oxygen vacancies. ? XRD data showed cell contraction well suited to the change of oxygen vacancies. ? Shift in hysteresis loop due to defect-induced exchange bias was observed.

  5. Structure of the C-type lectin carbohydrate recognition domain of human tetranectin

    DEFF Research Database (Denmark)

    Kastrup, J S; Nielsen, B B

    1998-01-01

    Tetranectin (TN) is a C-type lectin involved in fibrinolysis, being the only endogenous ligand known to bind specifically to the kringle 4 domain of plasminogen. TN was originally isolated from plasma, but shows a wide tissue distribution. Furthermore, TN has been found in the extracellular matrix of certain human carcinomas, whereas none or little is present in the corresponding normal tissue. The crystal structure of full-length trimeric TN (2.8 A resolution) has recently been published [Nielsen et al. (1997). FEBS Lett. 412, 388-396]. The crystal structure of the carbohydrate recognition domain (CRD) of human TN (TN3) has been determined separately at 2.0 A resolution in order to obtain detailed information on the two calcium binding sites. This information is essential for the elucidation of the specificity of TN towards oligosaccharides. TN3 crystallizes as a dimer, whereas it appears as a monomer in solution. The overall fold of TN3 is similar to other known CRDs. Each monomer is built of two distinct regions, one region consisting of six beta-strands and two alpha-helices, and the other region is composed of four loops harboring two calcium ions. The calcium ion at site 1 forms an eightfold coordinated complex and has Asp116, Glu120, Gly147, Glu150, Asn151, and one water molecule as ligands. The calcium ion at site 2, which is believed to be involved in recognition and binding of oligosaccharides, is sevenfold coordinated with ligands Gln143, Asp145, Glu150, Asp165, and two water molecules. One sulfate ion has been located at the surface of TN3, forming contacts to Glu120, Lys148, Asn106 of a symmetry-related molecule, and to an ethanol molecule.

  6. Ethnic skin types: are there differences in skin structure and function?

    Science.gov (United States)

    Rawlings, A V

    2006-04-01

    People of skin of colour comprise the majority of the world's population and Asian subjects comprise more than half of the total population of the earth. Even so, the literature on the characteristics of the subjects with skin of colour is limited. Several groups over the past decades have attempted to decipher the underlying differences in skin structure and function in different ethnic skin types. However, most of these studies have been of small scale and in some studies interindividual differences in skin quality overwhelm any racial differences. There has been a recent call for more studies to address genetic together with phenotypic differences among different racial groups and in this respect several large-scale studies have been conducted recently. The most obvious ethnic skin difference relates to skin colour which is dominated by the presence of melanin. The photoprotection derived from this polymer influences the rate of the skin aging changes between the different racial groups. However, all racial groups are eventually subjected to the photoaging process. Generally Caucasians have an earlier onset and greater skin wrinkling and sagging signs than other skin types and in general increased pigmentary problems are seen in skin of colour although one large study reported that East Asians living in the U.S.A. had the least pigment spots. Induction of a hyperpigmentary response is thought to be through signaling by the protease-activated receptor-2 which together with its activating protease is increased in the epidermis of subjects with skin of colour. Changes in skin biophysical properties with age demonstrate that the more darkly pigmented subjects retaining younger skin properties compared with the more lightly pigmented groups. However, despite having a more compact stratum corneum (SC) there are conflicting reports on barrier function in these subjects. Nevertheless, upon a chemical or mechanical challenge the SC barrier function is reported to be stronger in subjects with darker skin despite having the reported lowest ceramide levels. One has to remember that barrier function relates to the total architecture of the SC and not just its lipid levels. Asian skin is reported to possess a similar basal transepidermal water loss (TEWL) to Caucasian skin and similar ceramide levels but upon mechanical challenge it has the weakest barrier function. Differences in intercellular cohesion are obviously apparent. In contrast reduced SC natural moisturizing factor levels have been reported compared with Caucasian and African American skin. These differences will contribute to differences in desquamation but few data are available. One recent study has shown reduced epidermal Cathepsin L2 levels in darker skin types which if also occurs in the SC could contribute to the known skin ashing problems these subjects experience. In very general terms as the desquamatory enzymes are extruded with the lamellar granules subjects with lowered SC lipid levels are expected to have lowered desquamatory enzyme levels. Increased pores size, sebum secretion and skin surface microflora occur in Negroid subjects. Equally increased mast cell granule size occurs in these subjects. The frequency of skin sensitivity is quite similar across different racial groups but the stimuli for its induction shows subtle differences. Nevertheless, several studies indicate that Asian skin maybe more sensitive to exogenous chemicals probably due to a thinner SC and higher eccrine gland density. In conclusion, we know more of the biophysical and somatosensory characteristics of ethnic skin types but clearly, there is still more to learn and especially about the inherent underlying biological differences in ethnic skin types. PMID:18492142

  7. Equilibrium structures of Type 304 and Type 316 stainless steel in the temperature range 800/sup 0/F to 1500/sup 0/F: a metallographic review

    Energy Technology Data Exchange (ETDEWEB)

    Bagnall, C.; Shiels, S.A.

    1976-01-01

    The phase diagrams depicted in this report serve as a general guide to the structures that may be found in Type 304 and Type 316 stainless steels as thermodynamic equilibrium is approached. The influences of cold work and stress, however, are not indicated but will tend to cause reactions to proceed more rapidly or to take place where they are not normally favored. A large change in grain size from those shown (ASTM 8-9), will also have an effect on the distribution of the second phases. The proposed mechanism for sigma formation in Type 304 SS requires substantiation with additional experimental evidence over the 1100-1500/sup 0/F temperature range using material containing carbon up to the H-grade level of 1000 ppM.

  8. Synthesis and crystal structures of novel LaOAgS-type alkaline earth – Zinc, manganese, and cadmium fluoride pnictides

    Energy Technology Data Exchange (ETDEWEB)

    Charkin, Dmitri O., E-mail: charkin@inorg.chem.msu.ru; Urmanov, Arthur V.; Plokhikh, Igor V.; Korshunov, Alexander D.; Kuznetsov, Alexey N.; Kazakov, Sergey M.

    2014-02-05

    Highlights: • Sight new alkaline earth – Mn, Zn, Cd fluoride pnictides were prepared. • All new compounds adopt the LaOAgS structure type. • Bond distances in their structures are transferable within 2–3%. • Very close similarities are observed in structural chemistry of LaOAgS- and HfCuSi{sub 2}-type compounds of Mn, Cu, Zn, Ag, and Cd. -- Abstract: Systematic studies of the LaOAgS-type compounds among alkaline earth – Zn/Cd/Mn fluoride pnictides revealed the existence of new representatives SrFMnP, SrFMnAs, SrFMnSb, SrFZnAs, SrFZnSb, BaFZnAs, BaFCdP, and BaFCdAs. Similar to rare-earth oxide compounds and contrary to isolobal chalcogenides of Cu/Ag, not all possible compositions could be realized. No compound of the structure type is formed for calcium; strontium forms fluoride pnictides only with zinc and manganese, while for barium, new representatives are also formed with cadmium. This trend, which possibly has a geometrical origin, is corroborated by quantum chemical calculations. Formation of NdOZnP-type compounds also was not observed suggesting the structure to be characteristic only for rare earth – zinc oxide phosphides.

  9. Synthesis and crystal structures of novel LaOAgS-type alkaline earth – Zinc, manganese, and cadmium fluoride pnictides

    International Nuclear Information System (INIS)

    Highlights: • Sight new alkaline earth – Mn, Zn, Cd fluoride pnictides were prepared. • All new compounds adopt the LaOAgS structure type. • Bond distances in their structures are transferable within 2–3%. • Very close similarities are observed in structural chemistry of LaOAgS- and HfCuSi2-type compounds of Mn, Cu, Zn, Ag, and Cd. -- Abstract: Systematic studies of the LaOAgS-type compounds among alkaline earth – Zn/Cd/Mn fluoride pnictides revealed the existence of new representatives SrFMnP, SrFMnAs, SrFMnSb, SrFZnAs, SrFZnSb, BaFZnAs, BaFCdP, and BaFCdAs. Similar to rare-earth oxide compounds and contrary to isolobal chalcogenides of Cu/Ag, not all possible compositions could be realized. No compound of the structure type is formed for calcium; strontium forms fluoride pnictides only with zinc and manganese, while for barium, new representatives are also formed with cadmium. This trend, which possibly has a geometrical origin, is corroborated by quantum chemical calculations. Formation of NdOZnP-type compounds also was not observed suggesting the structure to be characteristic only for rare earth – zinc oxide phosphides

  10. On SYM theory and all order Bulk Singularity Structures of BPS Strings in type II theory

    CERN Document Server

    Hatefi, Ehsan

    2016-01-01

    The complete form of the S-matrix elements of three supersymmetric Yang-Mills (SYM), namely a transverse scalar field, two world volume gauge fields and a Potential $C_{n-1}$ Ramond-Ramond (RR) form field has been investigated. Basically, in order to find out an infinite number of $t,s, (t+s+u)$ channel bulk singularity structures of that particular mixed closed-open amplitude, we employ all the conformal field theory techniques to $$ and explore all the entire correlation functions as well as all order $\\alpha'$ contact interactions of these SYM couplings. The comparisons with the other symmetric analysis $$ and $$ are also carried out in detail. Various couplings from pull-Back of branes, Myers terms and several generalized Bianchi identities should be taken into account to be able to reconstruct all order $\\alpha'$ bulk singularities of type IIB(IIA) superstring theory. Finally, we make a comment on how to derive without any ambiguity all order $\\alpha'$ contact terms of those elements of the S-matrix that...

  11. Depleted cores, multi-component fits, and structural parameter relations for luminous early-type galaxies

    CERN Document Server

    Dullo, Bililign T

    2013-01-01

    New surface brightness profiles from 26 early-type galaxies with partially depleted cores have been extracted from the full radial extent of Hubble Space Telescope images, giving us a total sample of 31 such core-Sersic galaxies. We have carefully quantified the radial stellar distributions of the elliptical galaxies using the core-Sersic model whereas for the lenticular galaxies a core-Sersic bulge plus an exponential disc model gives the best representation. We additionally caution about the excessive use of multiple Sersic functions for decomposing galaxies. The structural parameters obtained from our fitted models are used to update several `central' as well as `global' galaxy scaling relations. We find near-linear relations between the break radius R_b and the spheroid luminosity L such that R_b ~ L^(1.13 +/- 0.13), and with the supermassive black hole mass M_BH such that R_b ~ M_BH^(0.83+/- 0.21). This is internally consistent with the notion that major, dry mergers add the stellar and black hole mass i...

  12. Effect of bow-type initial imperfection on reliability of minimum-weight, stiffened structural panels

    Science.gov (United States)

    Stroud, W. Jefferson; Krishnamurthy, Thiagaraja; Sykes, Nancy P.; Elishakoff, Isaac

    1993-01-01

    Computations were performed to determine the effect of an overall bow-type imperfection on the reliability of structural panels under combined compression and shear loadings. A panel's reliability is the probability that it will perform the intended function - in this case, carry a given load without buckling or exceeding in-plane strain allowables. For a panel loaded in compression, a small initial bow can cause large bending stresses that reduce both the buckling load and the load at which strain allowables are exceeded; hence, the bow reduces the reliability of the panel. In this report, analytical studies on two stiffened panels quantified that effect. The bow is in the shape of a half-sine wave along the length of the panel. The size e of the bow at panel midlength is taken to be the single random variable. Several probability density distributions for e are examined to determine the sensitivity of the reliability to details of the bow statistics. In addition, the effects of quality control are explored with truncated distributions.

  13. Structural characterization and anti-tumor effects of an inulin-type fructan from Atractylodes chinensis.

    Science.gov (United States)

    Xu, Jing; Chen, Dan; Liu, Chang; Wu, Xiong-Zhi; Dong, Cai-Xia; Zhou, Jing

    2016-01-01

    A fructan (ACPS-1) with a molecular weight of 11.2kDa was isolated from Atractylodes chinensis rhizome and characterized by chemical derivatization, HPLC, GC-MS, FT-IR, and NMR. Structural analyses revealed that ACPS-1 is predominately composed of fructose and a small amount of glucose and a polymerization degree of about 53. The fructan was deduced to be an inulin-type fructan containing a linear backbone composed of (2→1)-linked β-d-Fruf residues. The in vitro antitumor activity of ACPS-1 was evaluated on four human cancer cell lines, including a cervical cancer cell line (Hela), two liver hepatocellular carcinoma cell lines (HepG2 and 7721), and an ovarian carcinoma cell line (Skov3). Results showed that ACPS-1 could significantly inhibit Hela, HepG2, and 7721 cell proliferation, especially HepG2, for which the fructan showed a proliferative inhibition rate as high as 87.40%. This result suggests that ACPS-1 may have anticancer potentiality against hepatocellular carcinoma and warrants further investigation. PMID:26522246

  14. Benthic assemblages on artificial reefs in the northwestern Adriatic Sea: does structure type and age matter?

    Science.gov (United States)

    Ponti, Massimo; Fava, Federica; Perlini, Rossella Angela; Giovanardi, Otello; Abbiati, Marco

    2015-03-01

    The use of artificial reefs is on the rise worldwide. While their fish aggregating effects are well known, the epibenthic assemblages have been poorly investigated. Two types of artificial reefs (pyramids of concrete slabs and bundles of concrete tubes) have been deployed out of the Po River Delta in 2006 and 2010. The epibenthic assemblages were investigated in 2009 and 2012. Benthic assemblages on both structure typologies were dominated by species tolerating high sedimentation rates. Dissimilarities were found among assemblages with different ages, and, in less extend, between reef typologies. Colonisation by Mytilus galloprovincialis and other major space occupiers did not follow a clear succession pattern and was not affected by reef typology. Species colonisation was likely driven by variability in environmental conditions and recruitment processes rather than by reef typology. This study suggests that environmental features of the deployment sites should be carefully considered in planning and designing artificial reefs, especially in eutrophic and turbid coastal waters, exposed to high river loads. PMID:25569857

  15. Physical properties of new cerium palladium phosphide with C6Cr23-type structure

    Directory of Open Access Journals (Sweden)

    T. Abe

    2014-01-01

    Full Text Available We have found that a cerium palladium phosphide crystallizes into a C6Cr23-type structure with atomic disorder. Prepared polycrystalline samples show a homogeneity range in the ternary Ce–Pd–P phase diagram. The physical properties of the highest-quality sample of Ce2.4Pd20.7P5.9 were investigated by measuring the magnetization, electrical resistivity and specific heat. No pronounced phase transition was observed down to 0.5 K. The Kondo screening of localized 4f electrons in metallic Ce2.4Pd20.7P5.9 appears to be weaker than that in the isostructural compounds of Ce3Pd20Si6 and Ce3Pd20Ge6. By a comparative study of Ce2.4Pd20.7P5.9 and Ce3Pd20X6 (X = Si, Ge, the competition between the Kondo temperature and ordering temperatures including the quadrupolar ordering temperature is briefly discussed.

  16. Modeling and simulation of a Stewart platform type parallel structure robot

    Science.gov (United States)

    Lim, Gee Kwang; Freeman, Robert A.; Tesar, Delbert

    1989-01-01

    The kinematics and dynamics of a Stewart Platform type parallel structure robot (NASA's Dynamic Docking Test System) were modeled using the method of kinematic influence coefficients (KIC) and isomorphic transformations of system dependence from one set of generalized coordinates to another. By specifying the end-effector (platform) time trajectory, the required generalized input forces which would theoretically yield the desired motion were determined. It was found that the relationship between the platform motion and the actuators motion was nonlinear. In addition, the contribution to the total generalized forces, required at the actuators, from the acceleration related terms were found to be more significant than the velocity related terms. Hence, the curve representing the total required actuator force generally resembled the curve for the acceleration related force. Another observation revealed that the acceleration related effective inertia matrix I sub dd had the tendency to decouple, with the elements on the main diagonal of I sub dd being larger than the off-diagonal elements, while the velocity related inertia power array P sub ddd did not show such tendency. This tendency results in the acceleration related force curve of a given actuator resembling the acceleration profile of that particular actuator. Furthermore, it was indicated that the effective inertia matrix for the legs is more decoupled than that for the platform. These observations provide essential information for further research to develop an effective control strategy for real-time control of the Dynamic Docking Test System.

  17. Dust grains and the structure of steady C-type magnetohydrodynamic shock waves in molecular clouds

    CERN Document Server

    Wardle, M

    1998-01-01

    I examine the role of dust grains in determining the structure of steady, cold, oblique C-type shocks in dense molecular gas. Gas pressure, the inertia of the charged components, and changes in ionisation are neglected. The grain charge and rate coefficients for electron-neutral and grain-neutral elastic scattering are assumed constant at values appropriate to the shock interior. An MRN size distribution is accounted for by estimating an effective grain abundance and Hall parameter for single-size grains. A one-parameter family of intermediate shocks exists for each shock speed v_s between the intermediate signal speed v_A cos theta and sqrt{2} v_A cot theta, where v_A is the preshock Alfven speed and theta is the angle between the preshock magnetic field and the normal to the shock front. In addition, there is a unique fast shock for each v_s > v_A. If the preshock density n_H is greater than about 10^5 cm^-3 and the preshock magnetic field satisfies B(mG) less than about n_H(10^5 cm^-3) grains are partially...

  18. The structure of TeV-bright shell-type supernova remnants

    CERN Document Server

    Yang, Chuyuan; Fang, Jun; Li, Hui

    2014-01-01

    Aims. Two-dimensional MHD simulations are used to model the emission properties of TeV-bright shell-type supernova remnants (SNRs) and to explore their nature. Methods. In the leptonic scenario for the TeV emission, the $\\gamma$-ray emission is produced via Inverse Compton scattering of background soft photons by high-energy electrons accelerated by the shocks of the SNRs. The TeV emissivity is proportional to the magnetic field energy density and MHD simulations can be used to model the TeV structure of such remnants directly. 2D MHD simulations for SNRs are then performed under the assumption that the ambient interstellar medium is turbulent with the magnetic field and density fluctuations following a Kolmogorov-like power-law spectrum. Results. (1) As expected, these simulations confirm early 1D and 2D modelings of these sources, namely the hydrodynamical evolution of the shock waves and amplification of magnetic field by Rayleigh-Taylor convective flows and by shocks propagating in a turbulent medium; (2)...

  19. Comparison of the microstructure of Hanford Type II concrete structures and test specimens

    International Nuclear Information System (INIS)

    High-level radioactive waste from the current waste management operation at Hanford is stored in underground reinforced concrete tanks with a steel liner on the sides and bottom. The removal of pumpable liquid results in a moist salt-cake of sodium salts that is relatively immobile compared to its original liquid state. Additional immobilization and isolation techniques are being studied to further improve waste isolation and containment. Retrieval of the waste and permanent disposal will be deferred until a permanent disposal mode and location is selected. The integrity of the storage tanks is of critical importance during this interim period. Technical studies and laboratory tests have been performed to determine the effect of the stored waste's temperatures and chemistry on the reinforced concrete's strength and elastic properties. However, relatively little attention has been given to studying or predicting very long-term behavior based on short-term specimen examination. This report describes the results of the first phase of a laboratory program for which the ultimate goal is the ability to predict the probable condition of Hanford Type II concrete structures after 100 years of more of lifetime. The purpose of this phase was the evaluation of the microstructure of several existing test and field samples of Hanford concrete, and to correlate microstructural data with the physical test measurements on hand from other programs and tasks

  20. Structural tailoring effects on the magnetic behavior of symmetric and asymmetric cubane-type Ni complexes.

    Science.gov (United States)

    Ponomaryov, Alexey N; Kim, Namseok; Hwang, Jaewon; Nojiri, Hiroyuki; van Tol, Johan; Ozarowski, Andrew; Park, Jena; Jang, Zeehoon; Suh, Byoungjin; Yoon, Sungho; Choi, Kwang-Yong

    2013-06-01

    Using two kinds of carboxylate ligands with small but significant differences in steric size, symmetric and asymmetric Fe(II) and Ni(II) cubanes have been synthesized in a controlled fashion. Fast sweeping pulsed field measurements showed magnetization hysteresis loops for two cubane-type molecular complexes, [Ni4(?-OMe)4(O2CAr(4F-Ph))4(HOMe)8] and [Ni4(?-OMe)4(O2CAr(Tol))4(HOMe)6], thus suggesting single-molecule magnet behavior. To differentiate the magnetic properties between the symmetric and asymmetric cubanes, detailed electron paramagnetic resonance (EPR) measurements were performed. From the EPR data, taken at various frequencies and temperatures, zero-field splitting parameters D, E, and other higher-order parameters for both cubane samples were extracted. Compared to the symmetric Ni-cubane, the asymmetric one shows an increase in the D and E values by about 20%, thereby suggesting structural engineering effects on the magnetic properties. By using the magnetic parameters determined by EPR, a static magnetization curve at 2?K and a temperature dependence of the magnetic susceptibility were simulated. A good agreement between theoretical and experimental data confirms the validity of the values obtained from EPR measurements. PMID:23509044

  1. Structure–performance relationships for cantilever-type piezoelectric energy harvesters

    International Nuclear Information System (INIS)

    This study provides comprehensive analysis of the structure–performance relationships in cantilever-type piezoelectric energy harvesters. It provides full understanding of the effect of all the practical global control variables on the harvester performance. The control variables considered for the analysis were material parameters, areal and volumetric dimensions, and configuration of the inactive and active layers. Experimentally, the output power density of the harvester was maximum when the shape of the beam was close to a square for a constant bending stiffness and a fixed beam area. Through analytical modeling of the effective stiffness for the piezoelectric bimorph, the conditions for enhancing the bending stiffness within the same beam volume as that of a conventional bimorph were identified. The harvester configuration with beam aspect ratio of 0.86 utilizing distributed inactive layers exhibited an giant output power of 52.5?mW and power density of 28.5?mW?cm?3 at 30?Hz under 6.9?m?s?2 excitation. The analysis further indicates that the trend in the output power with varying damping ratio is dissimilar to that of the efficiency. In order to realize best performance, the harvester should be designed with respect to maximizing the magnitude of output power.

  2. Quasiparticle band structures and thermoelectric transport properties of p-type SnSe

    Science.gov (United States)

    Shi, Guangsha; Kioupakis, Emmanouil

    2015-03-01

    We used density functional and many-body perturbation theory to calculate the band structure and electronic transport parameters of p-type SnSe both for the low-temperature Pnma and high-temperature Cmcm phases. The Pnma phase has an indirect band gap of 0.829 eV while the Cmcm has a direct band gap of 0.464 eV. Both phases exhibit multiple local band extrema within an energy range comparable to the thermal energy of carriers from the global extrema. We calculated the electronic transport coefficients within the constant relaxation time approximation as a function of doping concentration and temperature for single-crystal and polycrystalline materials to understand experimental measurements. The electronic transport coefficients are highly anisotropic and are strongly affected by bipolar transport effects at low doping and high temperature. Our results indicate that SnSe exhibits optimal thermoelectric performance at high temperature when doped in the 1019-1020 cm-3 range. This work was supported in part by the National Science Foundation (DMR-1254314) and in part by CSTEC, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science. Computational resources were provided by the DOE NERSC facility.

  3. Synthesis, structure and applications of [cis-dioxomolybdenum(VI)-(ONO)] type complexes

    Indian Academy of Sciences (India)

    Rajan Deepan Chakravarthy; Dillip Kumar Chand

    2011-03-01

    Oxo-molybdenum chemistry is of great interest since such units are found in the active sites of a majority of molybdo-enzymes. In order to mimic the biological systems, a number of oxo-molybdenum complexes have been synthesised and studied. This review describes synthesis, structure and applications of oxomolybdenum complexes particularly cis-MoO2(L)(D) where L stands for a dianionic tridentate ONO ligand and D for a donor solvent molecule/monodentate ligand. The ligand moieties are derived from Schiff base, hydrazide Schiff base and other related tridentate ligands L(H)2. The coordination geometry around the Mo center in these complexes can be best described as a distorted octahedron in which the ONO-tridentate ligand occupies meridional position with two anionic oxygen donors mutually trans and are cis to the oxygen centers of the cis-dioxo group. Mostly the applications of cis-MoO2-(ONO) type complexes seen in literature are oxo transfer reactions like epoxidation, sulfoxidation and phosphine oxidation reactions.

  4. Structure and evolution of low-mass W UMa type systems -- II. with angular momentum loss

    CERN Document Server

    Li, L; Zhang, F

    2004-01-01

    In a preceding paper, using Eggleton's evolution code we have discussed the structure and evolution of low-mass W UMa type contact binaries without angular momentum loss (AML). The models exhibit cyclic behavior about a state of marginal contact on a thermal time-scale. Part of the time of each cycle is spent in contact and part in a semi-detached state. According to observations, W UMa systems suffer AML. We present the models of low-mass contact binaries with AML due to gravitational wave radiation (GR) or magnetic stellar wind (MSW) are presented. We find that gravitational radiation cannot prevent the cyclic evolution of W UMa systems, and the effect of gravitational radiation on the cyclic behavior of contact binary evolution is almost negligible. We also find that the most likely AML mechanism for W UMa systems is magnetic braking, and that magnetic braking effects can increase the period of the cyclic evolution, and shorten the fraction of the time spent in the poor thermal contact state. If W UMa star...

  5. The structural and optical properties of type III human collagen biosynthetic corneal substitutes

    Science.gov (United States)

    Hayes, Sally; Lewis, Phillip; Islam, M. Mirazul; Doutch, James; Sorensen, Thomas; White, Tomas; Griffith, May; Meek, Keith M.

    2015-01-01

    The structural and optical properties of clinically biocompatible, cell-free hydrogels comprised of synthetically cross-linked and moulded recombinant human collagen type III (RHCIII) with and without the incorporation of 2-methacryloyloxyethyl phosphorylcholine (MPC) were assessed using transmission electron microscopy (TEM), X-ray scattering, spectroscopy and refractometry. These findings were examined alongside similarly obtained data from 21 human donor corneas. TEM demonstrated the presence of loosely bundled aggregates of fine collagen filaments within both RHCIII and RHCIII-MPC implants, which X-ray scattering showed to lack D-banding and be preferentially aligned in a uniaxial orientation throughout. This arrangement differs from the predominantly biaxial alignment of collagen fibrils that exists in the human cornea. By virtue of their high water content (90%), very fine collagen filaments (2–9 nm) and lack of cells, the collagen hydrogels were found to transmit almost all incident light in the visible spectrum. They also transmitted a large proportion of UV light compared to the cornea which acts as an effective UV filter. Patients implanted with these hydrogels should be cautious about UV exposure prior to regrowth of the epithelium and in-growth of corneal cells into the implants. PMID:26159106

  6. Structure and Kinematics of Early-Type Galaxies from Integral-Field Spectroscopy

    CERN Document Server

    Cappellari, Michele

    2016-01-01

    Observations of galaxy isophotes, longs-slit kinematics and high-resolution photometry suggested a possible dichotomy between two distinct classes of E galaxies. But these methods are expensive for large galaxy samples. Instead, integral-field spectroscopic can efficiently recognize the shape, dynamics and stellar population of complete samples of early-type galaxies (ETGs). These studies showed that the two main classes, the fast and slow rotators, can be separated using stellar kinematics. We showed there is a dichotomy in the dynamics of the two classes. The slow rotators are weakly triaxial and dominate above $M_{\\rm crit}\\approx2\\times10^{11} M_\\odot$. Below $M_{\\rm crit}$, the structure of fast rotators parallels that of spiral galaxies. There is a smooth sequence along which, the metals content, the enhancement in $\\alpha$-elements, and the "weight" of the stellar initial mass function, all increase with the CENTRAL mass density slope, or bulge mass fraction, while the molecular gas fraction correspond...

  7. XAFS study on the structure of ytterbium(III) trifluoromethanesulfonates as a new type catalyst

    International Nuclear Information System (INIS)

    Yb L3-edge XAFS spectroscopy was applied to study on the local structure around Yb atoms in ytterbium(III) trifluoromethanesulfonates (Yb(OTf)3) catalysts dissolved in various solution and those in Yb(OTf)3 chiral catalysts prepared by a choice of two types of achiral ligands. XAFS analyses showed the difference in the coordination number of oxygen atoms between Yb(OTf)3 catalysts dissolved in aqueous and nonaqueous solutions, suggesting the activation of the Yb(OTf)3 catalyst by the hydration. For the two Yb(OTf)3 chiral catalysts, both the catalysts were found to be present as trivalent ytterbium oligomer. Curve-fitting analysis of EXAFS showed that the Yb-Yb distance of two catalyst complexes is fairly different from each other, i.e., one is 3.68 A and the other 4.04 A, which is expected to explain the difference of the catalytic performance of the two chiral catalysts. (author)

  8. Molecular Structure, Membrane Interactions, and Toxicity of the Islet Amyloid Polypeptide in Type 2 Diabetes Mellitus

    Science.gov (United States)

    Caillon, Lucie; Hoffmann, Anais R. F.; Botz, Alexandra; Khemtemourian, Lucie

    2016-01-01

    Human islet amyloid polypeptide (hIAPP) is the major component of the amyloid deposits found in the pancreatic islets of patients with type 2 diabetes mellitus (T2DM). Mature hIAPP, a 37-aa peptide, is natively unfolded in its monomeric state but forms islet amyloid in T2DM. In common with other misfolded and aggregated proteins, amyloid formation involves aggregation of monomers of hIAPP into oligomers, fibrils, and ultimately mature amyloid deposits. hIAPP is coproduced and stored with insulin by the pancreatic islet ?-cells and is released in response to the stimuli that lead to insulin secretion. Accumulating evidence suggests that hIAPP amyloid deposits that accompany T2DM are not just an insignificant phenomenon derived from the disease progression but that hIAPP aggregation induces processes that impair the functionality and the viability of ?-cells. In this review, we particularly focus on hIAPP structure, hIAPP aggregation, and hIAPP-membrane interactions. We will also discuss recent findings on the mechanism of hIAPP-membrane damage and on hIAPP-induced cell death. Finally, the development of successful antiamyloidogenic agents that prevent hIAPP fibril formation will be examined. PMID:26636105

  9. Atomic structure of radiation damage in FCC-metals after different types of irradiation

    International Nuclear Information System (INIS)

    Full text: Experimental data on atomic structure of radiation damage (individual point defects and their small complexes, as well as radiation clusters, formed in non-overlapping cascade areas) in pure platinum after different types of irradiation were obtained. The basic purpose consists in the analysis of structure of radiation damage formed during ion implantation (E = 20 keV), and under irradiation with fast (E > 0.1 MeV) neutrons. For study of the defect structure initiated by irradiation, the method of field ion microscopy (FIM) was used. The FIM method makes it possible to carry out direct precise investigation on an atomic scale of defects of crystal lattice of a material on an atom-pure surface, and of cascades which cause atom displacement. At the same time the method allows analyzing the object of research in volume by controlled and sequential removal of surface atoms by an electric field at cryogenic temperatures. The purpose of this work was experimental investigation of radiation clusters, formed in pure platinum (purity of 99.99 %) after neutron irradiation in reactor RWW-2M at temperature 310 K up to fast neutrons fluence (E > 0,1 MeV) 6.7·1021m-'2 and 3.5·1022m-'2. Ion implantation of accelerated Ar+ beams carried out on an installation with a plasma source of charged particles, generation of ions working in a continuous mode. In the crystal lattice of platinum irradiated up to fluence 6.7·1021m-'2, radiation damage has been found. The found defects presented, as a rule, either separate vacancies or small vacancy complexes with the sizes comparable with interatomic distances, or presented interstitials. The structure of defects was revealed by controlled and sequential removal of surface atoms by an electric field. As a result of irradiation of platinum up to fluence 3.5·1022m-'2, in this material by methods of FIM many radiation clusters initiated by interaction of accelerated neutrons with the substance were revealed. It is established that these damaged areas represent depleted zones containing separate vacancies, and also small vacancy complexes, with a 'belt' of interstitial atoms. Quantitative estimation of the sizes of such radiation defects was carried out and their density in volume was experimentally established. By method FIM it is established, that after neutron irradiation of platinum at temperature 310 K up to fluence 3.5·1022m-'2 clusters were formed in it of 3.2 nanometers average size, with concentration ? 9·1022m-'3, at average concentration of vacancies in clusters 9 %. In this work an attempt has been made to find out spatial geometry of the depleted zones in the platinum irradiated up to fluence of fast neutrons 3.5·1022m-'2. The exterior shape of zone was generally found to be highly irregular as vacancies making them are located extremely irregularly. In investigation of defect structure of platinum after irradiation with Ar+ ions specimens with an atom-smooth surface were exposed to ion implantation preliminarily certified in FIM. The atomic structure of radiation damage, both on the implanted surface and in the subsurface volume, after various dozes of irradiation, has been finally analysed. It is established, that there is a strong dependence of the size and density of radiation defects on their depth bedding in a material. Comparison of the atomic structure of the defects received after different types of irradiation in pure platinum is carried out. The research described in this paper was made possible by grant No. 03-02-16560-a from the Russian Foundation for Basic Research, the Program of State Support to Leading Scientific Schools of the Russian Federation (grant No. NSh-639.2003.2), and also with the support from the Urals Branch of the Russian Academy of Sciences (the grant for young scientists and post-graduate students). (author)

  10. Structure and properties of rhombohedral CePd3Ga8: A variant of the cubic parent compound with BaHg11 structure type

    International Nuclear Information System (INIS)

    Single crystals of a new intermetallic gallide, R-CePd3Ga8, have been synthesized from excess molten gallium. Single-crystal X-ray diffraction reveals that R-CePd3Ga8 crystallizes in the R-3m space group with a=b=c=8.4903(10) Å and ?=?=?=89.993(17). R-CePd3Ga8 is a variant of the cubic BaHg11 structure type with three structural units: a Ce-centered polyhedron, a distorted cube of Pd2Ga6 and a Pd-centered cuboctahedron. The distortions of these units are compared to undistorted analogous units in intermetallic compounds with BaHg11 structure type. Field and temperature-dependent magnetization measurements on R-CePd3Ga8 reveal a paramagnetic material with strong antiferromagnetic correlations and a magnetization consistent with Ce3+. Electrical resistance measurements indicate Kondo behavior between localized Ce3+ magnetic moments. - Graphical Abstract: Single crystals of CePd3Ga8 have been synthesized from Ga flux. This new compound is the first rhombohedral variant of the cubic BaHg11 structure type. Highlights: ? Single crystals of CePd3Ga8 were synthesized from gallium flux. ? CePd3Ga8 is the first rhombohedral variant of the cubic BaHg11 structure type. ? Paramagnetic with antiferromagnetic correlations. ? Magnetization consistent with Ce3+.

  11. Nonlinear model of Schrodinger type: conservation laws, Hamiltonian structure, and complete integrability

    International Nuclear Information System (INIS)

    The authors propose a method for finding Lax type representations for nonlinear evolution (one-dimensional) equations of mathematical physics. It is shown that the Schroedinger-type nonlinear model admits a Lax-type representation and is a Hamiltonian completely integrable dynamical system. Exact quasiperiodic solutions of this system are obtained in terms of Riemann theta functions

  12. Riemann type algebraic structures and their differential-algebraic integrability analysis

    Directory of Open Access Journals (Sweden)

    Prykarpatsky A.K.

    2010-06-01

    Full Text Available The differential-algebraic approach to studying the Lax type integrability of generalized Riemann type equations is devised. The differentiations and the associated invariant differential ideals are analyzed in detail. The approach is also applied to studying the Lax type integrability of the well known Korteweg-de Vries dynamical system.

  13. Structure and properties of HS6-5-2 type HSS manufactured by different P/M methods

    OpenAIRE

    G. Matula; L. A. Dobrza?ski; Herranz, G.; A. Varez; Levenfeld, B.; J. M. Torralba

    2007-01-01

    Purpose: It has been demonstrated in the paper structure and properties of of high speed-steel HS6-5-2 type manufactured by different method of powder metallurgy.Design/methodology/approach: Light microscope, SEM, image analysis, hardness tests, density examination, transverse rupture strength tests, analysis of chemical composition by LECO apparatus.Findings: Basing on the investigations of the HS6-5-2 type high-speed steels reinforced with ceramics particles fabricated with Powder Met...

  14. Temperature-dependent structural studies of mullite-type Bi2Fe4O9

    Science.gov (United States)

    Murshed, M. Mangir; Nénert, Gwilherm; Burianek, Manfred; Robben, Lars; Mühlberg, Manfred; Schneider, Hartmut; Fischer, Reinhard X.; Gesing, Thorsten M.

    2013-01-01

    We report on the temperature-dependent structural studies on the mullite-type Bi2Fe4O9 compound. The crystal structures were determined using both powder X-ray diffraction and single crystal neutron diffraction. The thermal expansion of the cell parameters from smallest to largest occurred in the order a

  15. Structure-based design of 7-azaindole-pyrrolidine amides as inhibitors of 11?-hydroxysteroid dehydrogenase type I.

    Science.gov (United States)

    Valeur, Eric; Christmann-Franck, Serge; Lepifre, Franck; Carniato, Denis; Cravo, Daniel; Charon, Christine; Bozec, Sophie; Musil, Djordje; Hillertz, Per; Doare, Liliane; Schmidlin, Fabien; Lecomte, Marc; Schultz, Melanie; Roche, Didier

    2012-09-15

    Indole-pyrrolidines were identified as inhibitors of 11?-hydroxysteroid dehydrogenase type 1 (11?-HSD1) by high-throughput screening. Optimisation of the initial hit through structure-based design led to 7-azaindole-derivatives, with the best analogues displaying single digit nanomolar IC(50) potency. The modeling hypotheses were confirmed by solving the X-ray co-crystal structure of one of the lead compounds. These compounds were selective against 11?-hydroxysteroid dehydrogenase type 2 (selectivity ratio >200) and exhibited good inhibition of 11?-HSD1 (IC(50)<1?M) in a cellular model (3T3L1 adipocytes). PMID:22901389

  16. Zr$_5$Sb$_3$$_-$$_x$Ru$_x$, a new superconductor in the W$_5$Si$_3$ structure type

    OpenAIRE

    Xie, Weiwei; Luo, Huixia; Phelan, Brendan F.; Cava, Robert. J.

    2015-01-01

    We report that at low Ru contents, up to x = 0.2, the Zr$_5$Sb$_3$$_-$$_x$Ru$_x$ solid solution forms in the hexagonal Mn$_5$Si$_3$ structure type of the host (x = 0), but that at higher Ru contents (x = 0.4 - 0.6) the solid solution transforms into the tetragonal W$_5$Si$_3$ structure type. We find that tetragonal Zr$_5$Sb$_2$$_.$$_4$Ru$_0$$_.$$_6$ is superconducting at 5 K, significantly higher than the transition temperature of hexagonal Zr$_5$Sb$_3$ (x = 0), which has a ...

  17. Influence of Rotor Structure and Number of Phases on First and Second Order Characteristics of TOYOTA PRIUS Electrical Machine Type

    OpenAIRE

    ASLAN, Bassel; KORECKI, Julien; VIGIER, Thimoté; SEMAIL, Eric

    2011-01-01

    This paper investigates the influence of the rotor structure on torque and Flux weakening region of V-shape IPM machine from TOYOTA PRIUS type, more specifically, keeping always the same magnet volume, we study the effect of the open angle between the two magnet segments of each V-shape pole on the machine performance. Moreover, in order to examine the impact of phase number on the machine characteristics, PRIUS structure is transformed into 5-phase machine of the same type and dimensions. As...

  18. Structure and properties of ?-NaFeO2-type ternary sodium iridates

    Science.gov (United States)

    Baroudi, Kristen; Yim, Cindi; Wu, Hui; Huang, Qingzhen; Roudebush, John H.; Vavilova, Eugenia; Grafe, Hans-Joachim; Kataev, Vladislav; Buechner, Bernd; Ji, Huiwen; Kuo, Changyang; Hu, Zhiwei; Pi, Tun-Wen; Pao, Chiwen; Lee, Jyhfu; Mikhailova, Daria; Hao Tjeng, Liu; Cava, R. J.

    2014-02-01

    The synthesis, structure, and elementary magnetic and electronic properties are reported for layered compounds of the type Na3-xMIr2O6 and Na3-xM2IrO6, where M is a transition metal from the 3d series (M=Zn, Cu, Ni, Co, Fe and Mn). The rhombohedral structures, in space group R-3m, were determined by refinement of neutron and synchrotron powder diffraction data. No clear evidence for long range 2:1 or 1:2 honeycomb-like M/Ir ordering was found in the neutron powder diffraction patterns except in the case of M=Zn, and thus in general the compounds are best designated as sodium deficient ?-NaFeO2-type phases with formulas Na1-xM1/3Ir2/3O2 or Na1-xM2/3Ir1/3O2. Synchrotron powder diffraction patterns indicate that several of the compounds likely have honeycomb in-plane metal-iridium ordering with disordered stacking of the layers. All the compounds are sodium deficient under our synthetic conditions and are black and insulating. Weiss constants derived from magnetic susceptibility measurements indicate that Na0.62Mn0.61Ir0.39O2, Na0.80Fe2/3Ir1/3O2, Na0.92Ni1/3Ir2/3O2, Na0.86Cu1/3Ir2/3O2, and Na0.89Zn1/3Ir2/3O2 display dominant antiferromagnetic interactions. For Na0.90Co1/3Ir2/3O2 the dominant magnetic interactions at low temperature are ferromagnetic while at high temperatures they are antiferromagnetic; there is also a change in the effective moment. Low temperature specific heat measurements (to 2 K) on Na0.92Ni1/3Ir2/3O2 indicate the presence of a broad magnetic ordering transition. X-ray absorption spectroscopy shows that iridium is at or close to the 4+ oxidation state in all compounds. 23Na nuclear magnetic resonance measurements comparing Na2IrO3 to Na0.92Ni1/3Ir2/3O2 and Na0.89Zn1/3Ir2/3O2 provide strong indications that the electron spins are short-range ordered in the latter two materials. Na0.62Mn0.61Ir0.39O2, Na0.80Fe2/3Ir1/3O2, Na0.90Co1/3Ir2/3O2, Na0.92Ni1/3Ir2/3O2, Na0.86Cu1/3Ir2/3O2 and Na0.89Zn1/3Ir2/3O2 are spin glasses. (CSD-numbers: Na0.62Mn0.61Ir0.39O2: 426657, Na0.80Fe2/3Ir1/3O2: 426659, Na0.90Co1/3Ir2/3O2: 426658, Na0.92Ni1/3Ir2/3O2: 426656, Na0.86Cu1/3Ir2/3O2: 426655, and Na2.8ZnIr2O6: 426660.)

  19. Play types, structural history and distribution of Middle Buntsandstein gas fields in NW Germany. Observations and their genetic interpretation

    Energy Technology Data Exchange (ETDEWEB)

    Baerle, C.; Kuehn, M.; Sommer, J. [Wintershall Holding AG, Erdoelwerke Barnstorf (Germany); Clever, B. [Wintershall Noordzee B.V., Rijswijk (Netherlands); Karnin, W.D.; Gast, R.

    2008-10-23

    The Middle Buntsandstein is one of the most important gas reservoirs in the northwestern German area. So far, nearly 100 billion cubic meter gas could be proven in 26 gas fields. The authors of the contribution under consideration report on play type, structural history and distribution of Middle Buntsandstein gas fields in northwestern Germany. The Buntsandstein structures consist of a tectonic-halokinetic structural floor with the three types inversion play, late halogenetic play and early halogenetic play. The development of the Buntsandstein fields depends of the timing of the structural formation and the presence of migration windows. Beside classical migration windows in the Zechstein salina, the internal ranges of the Permian basin require an existence of disturbances which enable a migration of the carbon-generated gases by the second barrier.

  20. Intermetallic REPtZn compounds with TiNiSi-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Trinath; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2011-07-15

    The equiatomic rare earth compounds REPtZn (RE = Y, Pr, Nd, Gd-Tm) were synthesized from the elements in sealed tantalum tubes by high-frequency melting at 1500 K followed by annealing at 1120 K and quenching. The samples were characterized by powder X-ray diffraction. The structures of four crystals were refined from single-crystal diffractometer data: TiNiSi type, Pnma, a = 707.1(1), b = 430.0(1), c = 812.4(1) pm, wR2 = 0.066, 602 F{sup 2}, 21 variables for PrPt{sub 1.056}Zn{sub 0.944}; a = 695.2(1), b = 419.9(1), c = 804.8(1) pm, wR2 = 0.041, 522 F{sup 2}, 21 variables for GdPt{sub 0.941}Zn{sub 1.059}; a = 688.2(1), b = 408.1(1), c = 812.5(1) pm, wR2 = 0.041, 497 F{sup 2}, 22 variables for HoPt{sub 1.055}Zn{sub 0.945}; a = 686.9(1), b = 407.8(1), c = 810.4(1) pm, wR2 = 0.061, 779 F{sup 2}, 20 variables for ErPtZn. The single-crystal data indicate small homogeneity ranges REPt{sub 1{+-}}{sub x}Zn{sub 1{+-}}{sub x}. The platinum and zinc atoms build up three-dimensional [PtZn] networks (265 - 269 pm Pt-Zn in ErPtZn) in which the erbium atoms fill cages with coordination number 16 (6 Pt + 6 Zn +4E r). Bonding of the erbium atoms to the [PtZn] network proceeds via shorter RE-Pt distances, i.e. 288 - 293 pm in ErPtZn. (orig.)

  1. Intermetallic REPtZn compounds with TiNiSi-type structure

    International Nuclear Information System (INIS)

    The equiatomic rare earth compounds REPtZn (RE = Y, Pr, Nd, Gd-Tm) were synthesized from the elements in sealed tantalum tubes by high-frequency melting at 1500 K followed by annealing at 1120 K and quenching. The samples were characterized by powder X-ray diffraction. The structures of four crystals were refined from single-crystal diffractometer data: TiNiSi type, Pnma, a = 707.1(1), b = 430.0(1), c = 812.4(1) pm, wR2 = 0.066, 602 F2, 21 variables for PrPt1.056Zn0.944; a = 695.2(1), b = 419.9(1), c = 804.8(1) pm, wR2 = 0.041, 522 F2, 21 variables for GdPt0.941Zn1.059; a = 688.2(1), b = 408.1(1), c = 812.5(1) pm, wR2 = 0.041, 497 F2, 22 variables for HoPt1.055Zn0.945; a = 686.9(1), b = 407.8(1), c = 810.4(1) pm, wR2 = 0.061, 779 F2, 20 variables for ErPtZn. The single-crystal data indicate small homogeneity ranges REPt1±xZn1±x. The platinum and zinc atoms build up three-dimensional [PtZn] networks (265 - 269 pm Pt-Zn in ErPtZn) in which the erbium atoms fill cages with coordination number 16 (6 Pt + 6 Zn +4E r). Bonding of the erbium atoms to the [PtZn] network proceeds via shorter RE-Pt distances, i.e. 288 - 293 pm in ErPtZn. (orig.)

  2. Thermoelectric material including a multiple transition metal-doped type I clathrate crystal structure

    Science.gov (United States)

    Yang, Jihui (Lakeshore, CA); Shi, Xun (Troy, MI); Bai, Shengqiang (Shanghai, CN); Zhang, Wenqing (Shanghai, CN); Chen, Lidong (Shanghai, CN); Yang, Jiong (Shanghai, CN)

    2012-01-17

    A thermoelectric material includes a multiple transition metal-doped type I clathrate crystal structure having the formula A.sub.8TM.sub.y.sub.1.sup.1TM.sub.y.sub.2.sup.2 . . . TM.sub.y.sub.n.sup.nM.sub.zX.sub.46-y.sub.1.sub.-y.sub.2.sub.- . . . -y.sub.n.sub.-z. In the formula, A is selected from the group consisting of barium, strontium, and europium; X is selected from the group consisting of silicon, germanium, and tin; M is selected from the group consisting of aluminum, gallium, and indium; TM.sup.1, TM.sup.2, and TM.sup.n are independently selected from the group consisting of 3d, 4d, and 5d transition metals; and y.sub.1, y.sub.2, y.sub.n and Z are actual compositions of TM.sup.1, TM.sup.2, TM.sup.n, and M, respectively. The actual compositions are based upon nominal compositions derived from the following equation: z=8q.sub.A-|.DELTA.q.sub.1|y.sub.1-|.DELTA.q.sub.2|y.sub.2- . . . -|.DELTA.q.sub.n|y.sub.n, wherein q.sub.A is a charge state of A, and wherein .DELTA.q.sub.1, .DELTA.q.sub.2, .DELTA.q.sub.n are, respectively, the nominal charge state of the first, second, and n-th TM.

  3. Potential Use of Avocado Oil on Structured Lipids MLM-Type Production Catalysed by Commercial Immobilised Lipases

    OpenAIRE

    Caballero, Eduardo; Soto, Carmen; Olivares, Araceli; Altamirano, Claudia

    2014-01-01

    Structured Lipids are generally constituents of functional foods. Growing demands for SL are based on a fuller understanding of nutritional requirements, lipid metabolism, and improved methods to produce them. Specifically, this work was aimed to add value to avocado oil by producing dietary triacylglycerols (TAG) containing medium-chain fatty acids (M) at positions sn-1,3 and long-chain fatty acids (L) at position sn-2. These MLM-type structured lipids (SL) were produced by interesterificati...

  4. Investigation of the Structural Behavior and Maximum Bending Strength of Six Multiweb Beams with Three Types of Webs

    Science.gov (United States)

    Peterson, James P.; Bruce, Walter E., Jr.

    1959-01-01

    The results of bending tests on six multiweb beams of optimum weight-strength design are presented. The internal structure of the beams consisted of various combinations of two types of full-depth solid webs and a post-stringer web. The observed structural behavior, buckling load, and failing load of the beams are compared with results obtained by the use of existing methods of analysis and found to be quite predictable.

  5. Complete {sup 1}H and {sup 13}C NMR structural assignments for a group of four goyazensolide-type furanoheliangolides

    Energy Technology Data Exchange (ETDEWEB)

    Soares, Ana Carolina Ferreira; Silva, Aline Nazare; Matos, Priscilla Mendonca; Silva, Eder Henrique da; Heleno, Vladimir Constantino Gomes [Universidade de Franca, Franca, SP (Brazil). Nucleo de Pesquisas em Ciencias Exatas e Tecnologicas; Lopes, Norberto Peporine; Lopes, Joao Luis Callegari [Universidade de Sao Paulo (FCFRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Ciencias Farmaceuticas de Ribeirao Preto. Dept. de Quimica e Fisica; Sass, Daiane Cristina, E-mail: vheleno_05@yahoo.com.br [Universidade de Sao Paulo (FFCLRP/USP), Ribeirao Preto, SP (Brazil). Fac. de Filosofia, Ciencias e Letras de Ribeirao Preto. Dept. de Quimica

    2012-07-01

    Four goyazensolide-type sesquiterpene lactones - lychnofolide, centratherin, goyazensolide and goyazensolide acetate - were thoroughly studied by NMR experimental techniques. {sup 1}H NMR, {sup 13}C NMR {l_brace}{sup 1}H{r_brace}, COSY, HMQC, HMBC, J-res. and NOE experiments were performed to provide the needed structural information. Complete and unequivocal assignment, including the determination of all multiplicities, was obtained for each structure and the data collections are presented in tables (author)

  6. Complete 1H and 13C NMR structural assignments for a group of four goyazensolide-type furanoheliangolides

    International Nuclear Information System (INIS)

    Four goyazensolide-type sesquiterpene lactones - lychnofolide, centratherin, goyazensolide and goyazensolide acetate - were thoroughly studied by NMR experimental techniques. 1H NMR, 13C NMR {1H}, COSY, HMQC, HMBC, J-res. and NOE experiments were performed to provide the needed structural information. Complete and unequivocal assignment, including the determination of all multiplicities, was obtained for each structure and the data collections are presented in tables (author)

  7. Fixed-structure Control of LTI Systems with Polytopic-type Uncertainty: Application to Inverter-interfaced Microgrids

    OpenAIRE

    Sad Abadi, Mahdieh Sadat

    2016-01-01

    This thesis focuses on the development of robust control solutions for linear time-invariant interconnected systems affected by polytopic-type uncertainty. The main issues involved in the control of such systems, e.g. sensor and actuator placement, control configuration selection, and robust fixed-structure control design are included. The problem of fixed-structure control is intrinsically nonconvex and hence computationally intractable. Nevertheless, the problem has attracted considerab...

  8. The Structure of the Poxvirus A33 Protein Reveals a Dimer of Unique C-Type Lectin-Like Domains?

    OpenAIRE

    Su, Hua-Poo; Singh, Kavita; Gittis, Apostolos G.; Garboczi, David N

    2009-01-01

    The current vaccine against smallpox is an infectious form of vaccinia virus that has significant side effects. Alternative vaccine approaches using recombinant viral proteins are being developed. A target of subunit vaccine strategies is the poxvirus protein A33, a conserved protein in the Chordopoxvirinae subfamily of Poxviridae that is expressed on the outer viral envelope. Here we have determined the structure of the A33 ectodomain of vaccinia virus. The structure revealed C-type lectin-l...

  9. A new type of one-dimensional compound: Structure of Nb4(Te2)4Te4I

    International Nuclear Information System (INIS)

    The new infinite-chain niobium telluride iodide has been prepared by reaction of the elements at 893 K. Nb4(Te2)4Te4I represents a new one-dimensional structure type. The structure consists of [Nb4(Te2)4Te4I]∞ chains which are formed by the four-nuclear butterfly cluster units 'Nb4(Te2)4Te4' with the I atoms bridging between different cluster units. (orig.)

  10. Crystal structures and magnetic properties of iron (III)-based phosphates: Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Essehli, Rachid, E-mail: rachid_essehli@yahoo.fr [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Bali, Brahim El [Laboratory of Mineral Solid and Analytical Chemistry ' LCSMA' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Benmokhtar, Said [LCMS, Laboratoire de Chimie des Materiaux Solides, Departement de chimie, Faculte des Sciences Ben M' SIK, Casablanca (Morocco); Bouziane, Khalid [Physics Department, College of Science, Sultan Qaboos University, PO Box 36, Postal Code 123 Al Khod, Sultanate of Oman (Oman); Manoun, Bouchaib [Laboratoire de Physico-Chimie des Materiaux, Departement de Chimie, FST Errachidia, University Moulay Ismail, B.P. 509 Boutalamine, Errachidia (Morocco); Abdalslam, Mouner Ahmed [Materials Science, Technical University Darmstadt, Darmstadt (Germany); Ehrenberg, Helmut [IFW Dresden, Helmholtzstr. 20, D-01069 Dresden (Germany)

    2011-01-28

    Graphical abstract: A perspective view of the Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} structure along the [0 0 1] direction. Both compounds seem to exibit antiferromagnetic interactions between magnetic entities at low temperature. Display Omitted Research highlights: > Nasicon and Alluaudite compounds, Iron(III)-based phosphates, Crystal structures of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Magnetism behaviours of Na{sub 4}NiFe(PO{sub 4}){sub 3} and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3}. > Antiferromagnetism interactions. > Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na{sub 4}NiFe(PO{sub 4}){sub 3} (I) and Na{sub 2}Ni{sub 2}Fe(PO{sub 4}){sub 3} (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) A, c = 21.643(4) A, R{sub 1} = 0.041, wR{sub 2}=0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) A, b = 12.433(5) A, c = 6.431(2) A, {beta} = 113.66(4){sup o}, R{sub 1} = 0.043, wR{sub 2}=0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O{sub 6}] octahedra and [PO{sub 4}] tetrahedra forming [NiFe(PO{sub 4}){sub 3}]{sup 4+} units which align in chains along the c-axis. The Na{sup +} cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni{sub 2}O{sub 10}] units of edge-sharing [NiO{sub 6}] octahedra, which alternate with [FeO{sub 6}] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na{sup +}. The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Moessbauer measurements performed at 4.2 K. The corresponding temperature dependence of the reciprocal susceptibility {chi}{sup -1} follows a typical Curie-Weiss behaviour for T > 105 K. A canted AFM state is proposed for compound (II) below 46 K with a field-induced magnetic transition at H {approx} 19 kOe, revealed in the hysteresis loop measured at 5 K. This transition is most probably associated with a spin-flop transition.

  11. RF characteristic measurement of the model cavities towards development of C-band disk-loaded type accelerating structure

    International Nuclear Information System (INIS)

    We studied on a C-band accelerating structure for the higher pulse rate than 120 pps in SACLA (SPring-8 Angstrom Compact free electron LAser) facility. Due to increase in heat dissipation, the existing choke-mode type accelerating structure has distortions of the cavity diameter 1 ?m or more, which shifts the resonant frequency with about -130 kHz. We designed a new C-band disk-loaded type accelerating structure without the complicated choke structures to generate an accelerating gradient of more than 40 MV/m at the pulse rate. A cross sectional shape of iris designed an ellipsoidal curvature to reduce the maximum surface electric field. Thereby, the maximum surface electric field is 20% lower than the existing structure. We made three types of 9-cell model cavity to estimate the RF characteristics and to establish the fabrication process. As a result, the average shunt impedance of the model cavities was 64 M?/m. An accelerating gradient of 42 MV/m will be expected, when an input RF power of 80 MW is fed into the structure. (author)

  12. Structural Characterizations of Two Synthetic Ni-Ludwigites, and Some Semiempirical EHTB Calculations on the Ludwigite Structure Type

    Science.gov (United States)

    Norrestam, R.; Kritikos, M.; Nielsen, K.; Søtofte, I.; Thorup, N.

    1994-08-01

    The structures of two novel synthetic nickel-containing borates, Ni2CrO2BO3 and Ni2VO2BO3, have been investigated by single crystal X-ray diffraction techniques and shown to have the ludwigite structure. The space group symmetry of both borates is Pbam with Z = 4. The unit cell dimensions are a = 9.209(1), b = 12.121(1), and c = 2.9877(3) Å, for the Ni,Cr-borate, and a = 9.199(2), b = 12.211(2), and c = 2.988(1) Å for the Ni,V-borate. The structural model of the Ni,Cr-ludwigite has been refined on the basis of the 575 most significant (I > 3?(I)) reflections with sin(?)/? ? 0.9 Å,-1 to an R-value of 0.029. For the Ni,V-ludwigite refinement, the 617 most significant (I > 3?(I)) reflections with sin(?)/? ? 0.8 Å-1 yielded an R-value of 0.023. Although the scattering powers of the cation pairs Ni/Cr and Ni/V are very similar, the refined cation distributions at the mixed metal sites yield approximately electroneutral compounds. The observed structural arrangement with the higher charged cations coplanar to the borate anion planes in the crystal structure is apparently a salient feature for all members of the pinakiolite structure family. A general model for the ludwigite structure, with alternating metal charges along the walls of octahedra, is supported by some semi-empirical extended Hückel electronic band calculations performed on the homometallic Fe- and Co-ludwigites.

  13. Vertical and horizontal vegetation structure across natural and modified habitat types at Mount Kilimanjaro

    OpenAIRE

    Rutten, Gemma; Ensslin, Andreas; Hemp, Andreas; Fischer, Markus

    2015-01-01

    In most habitats, vegetation provides the main structure of the environment. This complexity can facilitate biodiversity and ecosystem services. Therefore, measures of vegetation structure can serve as indicators in ecosystem management. However, many structural measures are laborious and require expert knowledge. Here, we used consistent and convenient measures to assess vegetation structure over an exceptionally broad elevation gradient of 866–4550m above sea level at Mount Kilimanjaro, Tan...

  14. Different Types of Cell-to-Cell Connections Mediated by Nanotubular Structures

    OpenAIRE

    Verani?, Peter; Lokar, Maruša; Schütz, Gerhard J.; Weghuber, Julian; Wieser, Stefan; Hägerstrand, Henry; Kralj-Igli?, Veronika; Igli?, Aleš

    2008-01-01

    Communication between cells is crucial for proper functioning of multicellular organisms. The recently discovered membranous tubes, named tunneling nanotubes, that directly bridge neighboring cells may offer a very specific and effective way of intercellular communication. Our experiments on RT4 and T24 urothelial cell lines show that nanotubes that bridge neighboring cells can be divided into two types. The nanotubes of type I are shorter and more dynamic than those of type II, and they cont...

  15. Mild hydrothermal synthesis, crystal structure, photoluminescence properties and emission quantum yield of a new zirconium germanate with garnet-type structure

    International Nuclear Information System (INIS)

    The mild hydrothermal synthesis, crystal structure, photoluminescence properties and emission quantum yield of a new sodium zirconium germanate are reported. This material and the method for its preparation represent for the first time a germanium garnet-type material synthesized at autogenous pressure and temperature at 230 °C. The crystal structure was determined by starting from the crystallographic parameters of a common garnet structure and it represents not only a new chemical combination of atoms but also combination of oxidation states in garnet structure. The framework consists of interconnected corner sharing GeO4 tetrahedra and ZrO6 octahedra which form small cavities that accommodate charge compensation Na+ cations. In the course of synthesis the structure can be functionalized by in situ doping with different percentage of Eu3+ ions. This structural flexibility is used to explore the photoluminescent behavior of the active centers embedded in garnet-type host. The materials display the Eu3+5D0?7F0–4 transitions under excitation via intra-4f6 excitation levels and through the O2??Eu3+ ligand-to-metal charge transfer. A maximum 5D0 quantum efficiency and emission quantum yield values (ca. 0.28 and 0.04±0.01, respectively) were found for the low Eu3+-containing sample, suggesting the presence of concentration quenching effects at higher Eu3+-content (5%). - Graphical abstract: Na3Zr1.8Ge3O10(OH)2 prepared at mild hydrothermal conditions. Highlights: ? New zirconogermanate with garnet-type structure. ? Hydrothermal synthesis. ? Crystal structure. ? Photoluminescent properties.

  16. Mild hydrothermal synthesis, crystal structure, photoluminescence properties and emission quantum yield of a new zirconium germanate with garnet-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Ferdov, Stanislav, E-mail: sferdov@fisica.uminho.pt [Department of Physics, University of Minho, 4800-058 Guimares (Portugal); Ferreira, Rute A.S. [Department of Physics, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal); Lin Zhi; Wu Zhengying [Department of Chemistry, CICECO, University of Aveiro, 3810-193 Aveiro (Portugal)

    2012-06-15

    The mild hydrothermal synthesis, crystal structure, photoluminescence properties and emission quantum yield of a new sodium zirconium germanate are reported. This material and the method for its preparation represent for the first time a germanium garnet-type material synthesized at autogenous pressure and temperature at 230 Degree-Sign C. The crystal structure was determined by starting from the crystallographic parameters of a common garnet structure and it represents not only a new chemical combination of atoms but also combination of oxidation states in garnet structure. The framework consists of interconnected corner sharing GeO{sub 4} tetrahedra and ZrO{sub 6} octahedra which form small cavities that accommodate charge compensation Na{sup +} cations. In the course of synthesis the structure can be functionalized by in situ doping with different percentage of Eu{sup 3+} ions. This structural flexibility is used to explore the photoluminescent behavior of the active centers embedded in garnet-type host. The materials display the Eu{sup 3+5}D{sub 0}{yields}{sup 7}F{sub 0-4} transitions under excitation via intra-{sup 4}f{sub 6} excitation levels and through the O{sup 2-}{yields}Eu{sup 3+} ligand-to-metal charge transfer. A maximum {sup 5}D{sub 0} quantum efficiency and emission quantum yield values (ca. 0.28 and 0.04{+-}0.01, respectively) were found for the low Eu{sup 3+}-containing sample, suggesting the presence of concentration quenching effects at higher Eu{sup 3+}-content (5%). - Graphical abstract: Na{sub 3}Zr{sub 1.8}Ge{sub 3}O{sub 10}(OH){sub 2} prepared at mild hydrothermal conditions. Highlights: Black-Right-Pointing-Pointer New zirconogermanate with garnet-type structure. Black-Right-Pointing-Pointer Hydrothermal synthesis. Black-Right-Pointing-Pointer Crystal structure. Black-Right-Pointing-Pointer Photoluminescent properties.

  17. Stability and electronic structure of the complex K$_2$PtCl$_6$ structure-type hydrides

    CERN Document Server

    Halilov, S V; Sen-Gupta, M; Gupta, R

    2004-01-01

    The stability and bonding of the ternary complex K$_2$PtCl$_6$ structure hydrides is discussed using first principles density functional calculations. The cohesion is dominated by ionic contributions, but ligand field effects are important, and are responsible for the 18-electron rule. Similarities to oxides are discussed in terms of the electronic structure. However, phonon calculations for Sr$_2$RuH$_6$ also show differences, particularly in the polarizability of the RuH$_6$ octahedra. Nevertheless, the yet to be made compounds Pb$_2$RuH$_6$ and Be$_2$FeH$_6$ are possible ferroelectrics. The electronic structure and magnetic properties of the decomposition product, FeBe$_2$ are reported. Implications of the results for H storage are discussed.

  18. Effect of heat treatment on the phase composition, structure and magnetic properties of M-type barium hexaferrite

    Science.gov (United States)

    Pashkova, E. V.; Solovyova, E. D.; Kolodiazhnyi, T. V.; Ivanitskii, V. P.; Belous, A. G.

    2014-11-01

    Effect of the heat treatment of carbonate-hydroxide precipitates on the phase composition, structure and magnetic properties of M-type barium hexaferrite has been investigated using the M?ssbauer spectroscopy, X-ray phase analysis and magnetic measurements. The distribution of Fe3+ ions over structural sites of barium hexaferrite with different degree of ferritizations has been defined. The conditions of single-domain behavior of barium hexaferrite nanoparticles in the magnetic field have been discussed. Obtained results explain the formation of magnetic structure during the synthesis of barium hexaferrite. This information could further be used for optimizing conditions for synthesis of nanosized barium hexaferrite with high-level properties.

  19. Response Analyses of Tuned Mass Dampers to Structures Exposed to Vortex Loading of Simiu-Scanlan Type

    DEFF Research Database (Denmark)

    Andersen, Lars; Birch, N. W.; Hansen, A. H.; Skibelund, J.-O.

    2001-01-01

    Vortex-induced loads on slender one-dimensional structures vibrating at lock-in conditions consist of a self-induced part in phase with the velocity of the structure in addition to an additive, almost harmonially varying component representing the same type of load as the vortex-induced force on a fixed cylinder. Simiu and Scanlan (1996 Wind Effects on Structures. New York: John Wiley & Sons Inc.) have proposed a widely used model for the self-induced part of the load based on a van der Pol osci...

  20. Structure and properties of ?-NaFeO{sub 2}-type ternary sodium iridates

    Energy Technology Data Exchange (ETDEWEB)

    Baroudi, Kristen, E-mail: kbaroudi@princeton.edu [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Yim, Cindi [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Wu, Hui [NIST Center for Neutron Research, Gaithersburg, MD 20899-6102 (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States); Huang, Qingzhen [NIST Center for Neutron Research, Gaithersburg, MD 20899-6102 (United States); Roudebush, John H. [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Vavilova, Eugenia [Leibniz Institute for Solid State and Materials Research IFW, Dresden (Germany); Zavoisky Physical Technical Institute, Russian Academy of Sciences, Kazan (Russian Federation); Grafe, Hans-Joachim; Kataev, Vladislav [Leibniz Institute for Solid State and Materials Research IFW, Dresden (Germany); Buechner, Bernd [Leibniz Institute for Solid State and Materials Research IFW, Dresden (Germany); Institut für Festkörperphysik, Technische Universität Dresden, Dresden (Germany); Ji, Huiwen [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States); Kuo, Changyang; Hu, Zhiwei; Pi, Tun-Wen [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden (Germany); Pao, Chiwen; Lee, Jyhfu [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan, ROC (China); Mikhailova, Daria; Hao Tjeng, Liu [Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden (Germany); Cava, R.J. [Department of Chemistry, Princeton University, Princeton, NJ 08544 (United States)

    2014-02-15

    The synthesis, structure, and elementary magnetic and electronic properties are reported for layered compounds of the type Na{sub 3?x}MIr{sub 2}O{sub 6} and Na{sub 3?x}M{sub 2}IrO{sub 6}, where M is a transition metal from the 3d series (M=Zn, Cu, Ni, Co, Fe and Mn). The rhombohedral structures, in space group R?3m, were determined by refinement of neutron and synchrotron powder diffraction data. No clear evidence for long range 2:1 or 1:2 honeycomb-like M/Ir ordering was found in the neutron powder diffraction patterns except in the case of M=Zn, and thus in general the compounds are best designated as sodium deficient ?-NaFeO{sub 2}-type phases with formulas Na{sub 1?x}M{sub 1/3}Ir{sub 2/3}O{sub 2} or Na{sub 1?x}M{sub 2/3}Ir{sub 1/3}O{sub 2}. Synchrotron powder diffraction patterns indicate that several of the compounds likely have honeycomb in-plane metal–iridium ordering with disordered stacking of the layers. All the compounds are sodium deficient under our synthetic conditions and are black and insulating. Weiss constants derived from magnetic susceptibility measurements indicate that Na{sub 0.62}Mn{sub 0.61}Ir{sub 0.39}O{sub 2}, Na{sub 0.80}Fe{sub 2/3}Ir{sub 1/3}O{sub 2}, Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2}, and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2} display dominant antiferromagnetic interactions. For Na{sub 0.90}Co{sub 1/3}Ir{sub 2/3}O{sub 2} the dominant magnetic interactions at low temperature are ferromagnetic while at high temperatures they are antiferromagnetic; there is also a change in the effective moment. Low temperature specific heat measurements (to 2 K) on Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2} indicate the presence of a broad magnetic ordering transition. X-ray absorption spectroscopy shows that iridium is at or close to the 4+ oxidation state in all compounds. {sup 23}Na nuclear magnetic resonance measurements comparing Na{sub 2}IrO{sub 3} to Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2} and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2} provide strong indications that the electron spins are short-range ordered in the latter two materials. Na{sub 0.62}Mn{sub 0.61}Ir{sub 0.39}O{sub 2}, Na{sub 0.80}Fe{sub 2/3}Ir{sub 1/3}O{sub 2}, Na{sub 0.90}Co{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2} and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2} are spin glasses. (CSD-numbers: Na{sub 0.62}Mn{sub 0.61}Ir{sub 0.39}O{sub 2}: 426657, Na{sub 0.80}Fe{sub 2/3}Ir{sub 1/3}O{sub 2}: 426659, Na{sub 0.90}Co{sub 1/3}Ir{sub 2/3}O{sub 2}: 426658, Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}: 426656, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2}: 426655, and Na{sub 2.8}ZnIr{sub 2}O{sub 6}: 426660.) - Graphical abstract: Diffraction patterns of Na{sub 0.92}Ni{sub 1/3}Ir{sub 2/3}O{sub 2}, Na{sub 0.86}Cu{sub 1/3}Ir{sub 2/3}O{sub 2} and Na{sub 0.89}Zn{sub 1/3}Ir{sub 2/3}O{sub 2}: neutron diffraction patterns in the main panel and synchrotron diffraction in the insets. The patterns show a small amount of ordering in the transition metal iridium layer. Display Omitted - Highlights: • We report six ternary sodium iridates with the ?-NaFeO{sub 2} structure. • Compounds Na{sub 1?x}M{sub 1/3}Ir{sub 2/3}O{sub 2}, M=Co, Ni, Cu, Zn and Na{sub 1?x}M{sub 2/3}Ir{sub 1/3}O{sub 2}, M=Mn, Fe. • Rietveld refinement of powder neutron diffraction data. • All compounds are spin glasses. • NMR comparison to Na{sub 2}IrO{sub 3}.

  1. Crystal structure of YSiO2N and a reappraisal of the ''vaterite'' type, YBO3

    International Nuclear Information System (INIS)

    Intensity calculations on powder patterns of YSiO2N indicate it to have an ?-CaSiO3, pseudowollastonite structure. The great similarity to YBO3 led to an investigation of the ''pseudo-vaterite'' types which appear also to be, in fact, pseudowollastonites

  2. The type I error rate for in vivo Comet assay data when the hierarchical structure is disregarded

    DEFF Research Database (Denmark)

    Hansen, Merete Kjær; Kulahci, Murat

    2014-01-01

    The Comet assay is a sensitive technique for detection of DNA strand breaks. The experimental design of in vivo Comet assay studies are often hierarchically structured, which should be reWected in the statistical analysis. However, the hierarchical structure sometimes seems to be disregarded, and this imposes considerable impact on the type I error rate. This study aims to demonstrate the implications that result from disregarding the hierarchical structure. DiUerent combinations of the factor levels as they appear in a literature study give type I error rates up to 0.51 and for all combinations the type I error rate is greater than the nominal _ at 0.05. Closed-form expressions based on scaled F-distributions using the Welch-Satterthwaite approximation are provided to show how the type I error rate is aUected. With this study we hope to motivate researchers to be more precise regarding the exposition of the statistical methodology and to suitably account for the hierarchical structure of Comet assay data whenever present.

  3. Observation of a high burnup rim-type structure in an advanced plutonium-uranium carbide fuel

    International Nuclear Information System (INIS)

    The observation is reported of a 'rim-type' structure with small subgrains in an advanced plutonium-uranium carbide (U0.8Pu0.2)C fuel pin, which had been irradiated in the Dounreay Fast Reactor to a burnup of 8.3% FIMA. (orig.)

  4. Structures and physical properties of epsilon-FeSi-type and CsCl-type RuSi studied by first-principles pseudopotential calculations

    Science.gov (United States)

    Vocadlo; Price; Wood

    2000-06-01

    An investigation of the relative stability of the two known polymorphs of RuSi, having the epsilon-FeSi and CsCl structures, has been made by first-principles pseudopotential calculations. The resulting cell volumes and fractional coordinates at P = 0 are in good agreement with experiment. Application of high pressure to the epsilon-FeSi phase of RuSi is predicted to produce a structure having almost perfect sevenfold coordination. However, it appears that RuSi having the CsCl-type structure will be the thermodynamically most stable phase for pressures greater than 3.6 GPa. Fitting of the calculated internal energy versus volume to a fourth-order logarithmic equation of state led to values (at T = 0 K) for the bulk modulus, K0, of 202 and 244 GPa for the epsilon-FeSi and CsCl phases, respectively, in excellent agreement with experiment. Band-structure calculations for both phases are also presented. PMID:10877344

  5. Sibling Structure and Parental Sex-Typing of Children's Household Tasks.

    Science.gov (United States)

    Brody, Charles J.; Steelman, Lala Carr

    1985-01-01

    Tests whether an increase in number of sons in the family decreases the sex-typing of traditionally female tasks and whether an increase in the number of daughters increases sex-typing of traditionally female chores. Examines the reverse pattern for male chores. Results support the hypotheses for the female-specific tasks. (BH)

  6. Structural Stability of Riemann Solutions for a Multiphase Kinematic Conservation Law Model that Changes Type.

    Science.gov (United States)

    Vinod, Vaidyanath

    We consider a model for 2-way traffic flow introduced by Bick and Newell in 1960 (2). The model problem is: p_{t} + (pu)_{x } = 0; quad q_{t} + (qv)_ {x} = 0.eqno(0.1)Here p and q are the densities of cars in the two directions of flow and u and v are the respective velocities in the p and q directions; a choice suggested in (2) is u = 1 - p - beta q, v = -1 + q + beta p.. In this model, beta is a measure of the interaction between the two directions of flow. For the problem to be physically feasible, we require 0=0, q=0, and -1 + q + beta p>=0.. When beta = 0, there is no interaction between the two directions of flow and then the system (0.1) reduces to a system of scalar equation for which the Riemann problem (Cauchy problem) to (0.1) with initial data of the form: U(x,0) = cases{{U_0,quad x 0} cr}has a unique solution in the class of Lax entropy or admissible wave solutions. In this case, there is an open set of initial states (U_0, U_1) for which the solution exhibits the phenomenon of 'overlapping rarefaction waves'. These waves occupy the same position in the physical plane and they are stable. When beta>0, for the same initial values U_0 and U_1, these overlapping rarefaction solutions disappear due to the presence of an elliptic region. For these states, we introduce a new shock solution which we term a critical shock (this is qualitatively similar to a Buckley-Leverett shock). The strength of the shock goes to zero as beta tends to zero; and this solution approaches the overlapping wave solution. The main result of this thesis is that these constructed solutions are structurally stable as beta approaches zero (that is, the elliptic region shrinks to a line); and that they converge strongly in L^1. The construction might prove useful in solving other problems that change type, for example models for three-phase flow in porous media (1) or compressible two-phase flow (19). In this dissertation, we present the stability result for one new case, which typifies the difficulties involved.

  7. Structure and anelasticity of Fe3Ga and Fe3(Ga,Al) type alloys

    International Nuclear Information System (INIS)

    Highlights: • The A2 to D03 transition in quenched Fe–27Ga takes place at heating from 150 to 300 °C. • The L12 phase appears after incubation period at 350 °C and above. • The L12 phase formation is accompanied by a transient internal friction peak. • Substitution of Ga atoms by Al slows down the massive formation of the L12 phase. • TEM study of Fe–Ga–Al alloy proves weak D03 ordering and formation L12 phase. - Abstract: The structure of binary Fe–27at.%Ga and ternary Fe–18at.%Ga–6at.%Al alloys is studied after different annealing regimes of as quenched samples. This paper focuses mainly on early stages of different phase transitions: from A2 to D03, to L12 and D019, which decrease functional properties of Fe–Ga alloys. Formation of stable phases goes through formation of metastable phases: according to XRD, the D03 ordering of practically disordered A2 solid solution clearly takes place at 150 °C, while formation of equilibrium fcc ordered L12 phase starts after four hours annealing at 350 °C. Upon continuous heating, the transition from D03 to L12 phase is accompanied by a transient internal friction peak. On its turn, the phase transitions are retarded in the ternary Fe–18Ga–5Al alloy, although a careful TEM study of the ternary alloy proves weak D03 ordering in the as-quenched state and formation of small precipitates of L12 phase (not detectable by X-ray) after four hours annealing at 275 °C. The presence of carbon in studied alloys leads to appearance of Snoek-type relaxation in both binary and ternary alloys: the peak in binary Fe–27Ga alloy is unimodal with activation energy of about 1 eV, and it has bi-modal shape in the ternary alloy Fe–18Ga–5Al with activation energies of about 1.1 and 1.4 eV, corresponding to carbon atom diffusion under stress in vicinity of Ga and Al atoms, respectively

  8. Multi-virulence-locus sequence typing of Staphylococcus lugdunensis generates results consistent with a clonal population structure and is reliable for epidemiological typing.

    Science.gov (United States)

    Didi, Jennifer; Lemée, Ludovic; Gibert, Laure; Pons, Jean-Louis; Pestel-Caron, Martine

    2014-10-01

    Staphylococcus lugdunensis is an emergent virulent coagulase-negative staphylococcus responsible for severe infections similar to those caused by Staphylococcus aureus. To understand its potentially pathogenic capacity and have further detailed knowledge of the molecular traits of this organism, 93 isolates from various geographic origins were analyzed by multi-virulence-locus sequence typing (MVLST), targeting seven known or putative virulence-associated loci (atlLR2, atlLR3, hlb, isdJ, SLUG_09050, SLUG_16930, and vwbl). The polymorphisms of the putative virulence-associated loci were moderate and comparable to those of the housekeeping genes analyzed by multilocus sequence typing (MLST). However, the MVLST scheme generated 43 virulence types (VTs) compared to 20 sequence types (STs) based on MLST, indicating that MVLST was significantly more discriminating (Simpson's index [D], 0.943). No hypervirulent lineage or cluster specific to carriage strains was defined. The results of multilocus sequence analysis of known and putative virulence-associated loci are consistent with a clonal population structure for S. lugdunensis, suggesting a coevolution of these genes with housekeeping genes. Indeed, the nonsynonymous to synonymous evolutionary substitutions (dN/dS) ratio, the Tajima's D test, and Single-likelihood ancestor counting (SLAC) analysis suggest that all virulence-associated loci were under negative selection, even atlLR2 (AtlL protein) and SLUG_16930 (FbpA homologue), for which the dN/dS ratios were higher. In addition, this analysis of virulence-associated loci allowed us to propose a trilocus sequence typing scheme based on the intragenic regions of atlLR3, isdJ, and SLUG_16930, which is more discriminant than MLST for studying short-term epidemiology and further characterizing the lineages of the rare but highly pathogenic S. lugdunensis. PMID:25078912

  9. Structural models of the human copper P-type ATPases ATP7A and ATP7B

    DEFF Research Database (Denmark)

    Gourdon, Pontus; Sitsel, Oleg

    2012-01-01

    The human copper exporters ATP7A and ATP7B contain domains common to all P-type ATPases as well as class-specific features such as six sequential heavy-metal binding domains (HMBD1-HMBD6) and a type-specific constellation of transmembrane helices. Despite the medical significance of ATP7A and ATP7B related to Menkes and Wilson diseases, respectively, structural information has only been available for isolated, soluble domains. Here we present homology models based on the existing structures of soluble domains and the recently determined structure of the homologous LpCopA from the bacterium Legionella pneumophila. The models and sequence analyses show that the domains and residues involved in the catalytic phosphorylation events and copper transfer are highly conserved. In addition, there are only minor differences in the core structures of the two human proteins and the bacterial template, allowing protein-specific properties to be addressed. Furthermore, the mapping of known disease-causing missense mutations indicates that among the heavy-metal binding domains, HMBD5 and HMBD6 are the most crucial for function, thus mimicking the single or dual HMBDs found in most copper-specific P-type ATPases. We propose a structural arrangement of the HMBDs and how they may interact with the core of the proteins to achieve autoinhibition.

  10. Structure of the cytoplasmic domain of Yersinia pestis YscD, an essential component of the type III secretion system

    Energy Technology Data Exchange (ETDEWEB)

    Lountos, George T.; Tropea, Joseph E.; Waugh, David S. (SAIC); (NCI)

    2012-09-17

    The Yersinia pestis YscD protein is an essential component of the type III secretion system. YscD consists of an N-terminal cytoplasmic domain (residues 1-121), a transmembrane linker (122-142) and a large periplasmic domain (143-419). Both the cytoplasmic and the periplasmic domains are required for the assembly of the type III secretion system. Here, the structure of the YscD cytoplasmic domain solved by SAD phasing is presented. Although the three-dimensional structure is similar to those of forkhead-associated (FHA) domains, comparison with the structures of canonical FHA domains revealed that the cytoplasmic domain of YscD lacks the conserved residues that are required for binding phosphothreonine and is therefore unlikely to function as a true FHA domain.

  11. The Use of Metal Fluoride Compounds as Phosphate Analogs for Understanding the Structural Mechanism in P-type ATPases.

    Science.gov (United States)

    Danko, Stefania J; Suzuki, Hiroshi

    2016-01-01

    The membrane-bound protein family, P-type ATPases, couples ATP hydrolysis with substrate transport across the membrane and forms an obligatory auto-phosphorylated intermediate in the transport cycle. The metal fluoride compounds, BeF x , AlF x , and MgF x , as phosphate analogs stabilize different enzyme structural states in the phosphoryl transfer/hydrolysis reactions, thereby fixing otherwise short-lived intermediate and transient structural states and enabling their biochemical and atomic-level crystallographic studies. The compounds thus make an essential contribution for understanding of the ATP-driven transport mechanism. Here, with a representative member of P-type ATPase, sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA), we describe the method for their binding and for structural and functional characterization of the bound states, and their assignments to states occurring in the transport cycle. PMID:26695034

  12. Expression and characterization of P-type ATPases for structural studies

    OpenAIRE

    Chintalapati, Sivaram Chandra

    2007-01-01

    Two types of proteins transport ions across the membrane – ion channels and ion pumps. Ion pumps transport ions against their electrochemical gradient by co-transporting another ion or a substrate molecule through a concentration gradient or by coupling this process to an energy source like ATP. Those that couple ATP hydrolysis to ion transport are called ion motive ATPases and can be classified as ‘V’, ‘F’ and ‘P’ types. In this thesis, two sub-classes of P-type ATPases, PIIIA and PIB were s...

  13. Data with Hierarchical Structure: Impact of Intraclass Correlation and Sample Size on Type-I Error

    OpenAIRE

    Musca, Serban C.; Kamiejski, Rodolphe; Nugier, Armelle; Méot, Alain; Er-Rafiy, Abdelatif; Brauer, Markus

    2011-01-01

    Least squares analyses (e.g., ANOVAs, linear regressions) of hierarchical data leads to Type-I error rates that depart severely from the nominal Type-I error rate assumed. Thus, when least squares methods are used to analyze hierarchical data coming from designs in which some groups are assigned to the treatment condition, and others to the control condition (i.e., the widely used “groups nested under treatment” experimental design), the Type-I error rate is seriously inflated, leading too of...

  14. The solution structure of the MANEC-type domain from Hepatocyte Growth Factor Activator Inhibitor 1 reveals an unexpected PAN/apple domain-type fold

    DEFF Research Database (Denmark)

    Hong, Zebin; Nowakowski, Michal

    2015-01-01

    A decade ago, a Motif at N-terminus with Eight-Cysteines or in short MANEC was defined as a new protein domain family. This domain is found exclusively in the N-terminus of >400 multi-domain type-1 transmembrane proteins from animals. Despite the large number of MANEC-containing proteins, only one has been characterized at the protein level: hepatocyte growth factor activator inhibitor-1 (HAI-1). HAI-1 is an essential protein, as knockout mice die in utero due to placental defects. HAI-1 is an inhibitor of matriptase, hepsin and hepatocyte growth factor activator, all serine proteases with important roles in epithelial development, cell growth and homeostasis. Dysregulation of these proteases has been causatively implicated in pathological conditions such as skin diseases and cancer. Detailed functional understanding of HAI-1 and other MANEC-containing proteins is hampered by the lack of structural information on MANEC. Although many MANEC sequences exist, sequence-based database searches fail to predict structural homology. Here we present the NMR solution structure of the MANEC domain from HAI-1, the first three-dimensional structure from the MANEC domain family. Unexpectedly, MANEC is a new subclass of the PAN/apple domain family, with its own unifying features, such as two additional disulfide bonds, two extended loop regions and additional ?-helical elements. As shown for other PAN/apple domain-containing proteins, we propose a similar active role of the MANEC domain in intramolecular and intermolecular interactions. The structure provides a tool for the further elucidation of HAI-1 function as well as a reference for the study of other MANEC-containing proteins.

  15. A series of aluminum tungsten oxides crystallizing in a new ReO3-related structure type

    International Nuclear Information System (INIS)

    A series of new aluminum tungsten oxides with the general formula Al4W2nO6n+2 (n=4-7) was found and structurally characterized by electron diffraction, high-resolution transmission electron microscopy (HRTEM) and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). The structural model for Al4W10O32 (I4/mmm (space group no. 139); a?0.375, c?3.95 nm) consists of slabs of [5x?x?] corner-sharing WO6 octahedra that are connected via edge-sharing to AlO6 octahedra. Simulated HRTEM images agree well with the experimental ones and thus support the proposed structural model. The connection between adjacent slabs of WO3 via AlO6 octahedra represents a novel variant of crystallographic shear operation for ReO3-type structures. The crystallites display a wide range of stacking sequences that are frequently intergrown with each other. - Graphical abstract: A structural model for Al4W10O32 was derived from electron diffraction, HRTEM and HAADF-STEM observations. The ReO3-type structure of WO3 is sheared into five octahedra wide slabs that are connected via planes of AlO6 octahedra. Polytypes with different slab width exist and are frequently intergrown with each other

  16. BaAl4-type structure derivatives in the Ga-rich part of the Y–Cu–Ga system

    International Nuclear Information System (INIS)

    Highlights: ? We study the crystal structure of Ga-rich compounds in the Y–Cu–Ga system at 500 °C. ? Increasing of Ga-content leads to shift of composition to the higher Y concentration. ? We analyze the behavior of atomic vacancies in the Cu/Ga positions. ? Crystal structure of studied compounds is constructed from the BaAl4-like fragments. - Abstract: The crystal structures of seven Ga-rich compounds that exist in the Y–Cu–Ga system were studied by the X-ray single-crystal and powder diffraction methods. The crystal structures of six phases were shown to be constructed from the orthorhombic distorted BaAl4-like fragments by multiplication of its a and b lattice constants. These compounds are: 1-Y1.02Cu1.35Ga2.63 (modified BaAl4-type structure, 1 × 1 multiplication), 2-Y1.04Cu1.12Ga2.84 and 3-Y1.05Cu1.00Ga2.95 (own type structure, 3 × 3), 4-Y1.08Cu0.72Ga3.20 (own, 9 × 9), 5-Y3Cu4Ga7 and 6-Y3.21Cu3.09Ga7.70 (La3Al11, 3 × 1), 7-YCuGa2 (own, 3 × 3).

  17. Evaluating response modification factor (R for some types of steel structure

    Directory of Open Access Journals (Sweden)

    Doralba Valencia Restrepo

    2010-04-01

    Full Text Available Response modification factor (R, tabulated in the Colombian Design Code as NSR-98, is used in this paper for eva-luating internal member forces produced by design earthquake action on steel structures and the inconsistencies pre-sent when designing structures when 1% drift limits must be complied with. The article presents the design of 45 frames corresponding to the seismic resistance system of 5 buildings: 15 special moment frames (SMF, 15 special concentrically-braced frames (CBF and 15 eccentrically-braced frames (EBF. External loads and their combination were used in estimating internal loads and rigidity demands (1% drift were evaluated in line with NSR-98 requi-rements. Member strength requirements were evaluated by using the AISC-2005 seismic provisions for steel structu-red buildings. Modal pushover analysis was used for evaluating the response modification factor for the 45 given frames at different structural performance levels. It was found that this factor was not constant for any of the three structural systems (SMF, CBF and EBF suggested by NSR-98 and that the values of the response modification factor found in the present investigation were smaller than those tabulated in this design code governing everyday structural design. This would lead to significant errors being made in evaluating design forces, not only in the structures but in the support elements (base-plates, foundations, shear walls and any structures attached to buildings constructed in line with the seismic resistance system.

  18. Structural and Genetic Characterization of the Shigella boydii Type 13 O Antigen

    OpenAIRE

    Feng, Lu; Senchenkova, Sof'ya N.; Yang, Jinghua; Shashkov, Alexander S; Tao, Jiang; Guo, Hongjie; Zhao, Guang; Knirel, Yuriy A.; Reeves, Peter; Wang, Lei

    2004-01-01

    Shigella is an important human pathogen. It is generally agreed that Shigella and Escherichia coli constitute a single species; the only exception is Shigella boydii type 13, which is more distantly related to E. coli and other Shigella forms and seems to represent another species. This gives S. boydii type 13 an important status in evolution. O antigen is the polysaccharide part of the lipopolysaccharide in the outer membrane of gram-negative bacteria and plays an important role in pathogeni...

  19. Crystal structure and electron density of Imma perovskite-type oxynitride LaTiO2N. Structural origin of visible-light response

    International Nuclear Information System (INIS)

    Highly crystalline lanthanum titanium oxynitride LaTiO2N has been determined to have an Imma perovskite-type structure with a0b-b- tilt system by the electron, neutron and synchrotron diffraction experiments. The refined crystallographic parameters agree well with those of the optimized structure obtained by density functional theory-based calculations. Experimental and theoretical electron densities indicate the covalent bonding between Ti cation and N,O anions. The covalent bonding and existence of N atoms are responsible for the reduced bend gap, which leads to the visible-light response of LaTiO2N photocatalyst. (author)

  20. Metal-rich phosphides RE5Ir19P12 with Sc5Co19P12 type structure

    International Nuclear Information System (INIS)

    The iridium-rich phosphides RE5Ir19P12 (RE=Sc, Y, La-Nd, Sm-Lu) with Sc5Co19P12 type structure, space group P62-bar m were synthesized by solid state reactions of the elements in tantalum crucibles. Well shaped single crystals were obtained in bismuth fluxes. All phosphides were characterized on the basis of X-ray powder data. The structures of RE5Ir19P12 with RE=Sc, La, Ce, Dy, Er, Tm, and Yb were refined from single crystal diffractometer data. The complex structure of these phosphides can be described by an intergrowth of simpler ThCr2Si2 and SrPtSb related slabs. Striking structural motifs of the RE5Ir19P12 structures are slightly distorted tricapped trigonal prisms of the metal atoms around the phosphorus atoms. The iridium and phosphorus atoms build up three-dimensional [Ir19P12] polyanionic networks (230-286 pm Ir-P and 282-296 pm Ir-Ir in La5Ir19P12) which leave cavities of coordination numbers 16 and 15 for the rare earth atoms. - Graphical Abstract: The intergrowth structure La5Ir19P12. Highlights: ? Metal flux syntheses of intermetallic compounds. ? Synthesis and structure of new phosphides RE5Ir19P12. ? Crystal chemistry of metal-rich phosphides. ? Description of the RE5Ir19P12 structure as an intergrowth variant.

  1. Effect of preparation conditions on fractal structure and phase transformations in the synthesis of nanoscale M-type barium hexaferrite

    International Nuclear Information System (INIS)

    The conditions of the synthesis of carbonate-hydroxide precursors (pH of FeOOH precipitation and heat treatment regimes) were studied in terms of their effect on the fractal structure and physical-chemical properties of precursors. Phase transformations which occur during the synthesis of nanosize M-type barium hexaferrite (BHF) were studied as well. The first structural level of precursors' aggregation for mass fractals, the correlation between fractal dimension and precursors' activity during the synthesis of BHF were determined. Synthesis parameters for the precursors with the optimal fractal structure were determined. These data permit an enhancement of the filtration coefficient of the precipitates by a factor of 4-5, obtaining substantial decrease in the temperature required for synthesis of a single-phase BHF, and monodispersed plate-like nanoparticles (60 nm diameter) with the shape anisotropy and good magnetic characteristics (saturation magnetization (Ms)=68,7 emu/g and coercitivity (Hc)=5440 Oe). - Highlights: ? The nanosize M-type BHF obtained by precipitation of hydroxicarbonates technique. ? Optimal fractal structure of a precursor for nanosize M-type BHF has been determined. ? The precursor precipitated at pH 4.3 allows getting monodisperse particles of BHF.

  2. Effect of preparation conditions on fractal structure and phase transformations in the synthesis of nanoscale M-type barium hexaferrite

    Energy Technology Data Exchange (ETDEWEB)

    Pashkova, E.V. [V.I. Vernadskii Institute of General and Inorganic Chemistry, 32/34 Prospect Palladina, Kyiv-142, 03680 (Ukraine); Solovyova, E.D., E-mail: solovyovak@mail.ru [V.I. Vernadskii Institute of General and Inorganic Chemistry, 32/34 Prospect Palladina, Kyiv-142, 03680 (Ukraine); Kotenko, I.E., E-mail: Hab2420@yahoo.com [National Technical University of Ukraine ' KPI' , Pr. Pobedy, 37, Kyiv-57 (Ukraine); Kolodiazhnyi, T.V., E-mail: kolodiazhnyi.taras@nims.go.jp [National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Belous, A.G., E-mail: belous@ionc.kar.net [V.I. Vernadskii Institute of General and Inorganic Chemistry, 32/34 Prospect Palladina, Kyiv-142, 03680 (Ukraine)

    2011-10-15

    The conditions of the synthesis of carbonate-hydroxide precursors (pH of FeOOH precipitation and heat treatment regimes) were studied in terms of their effect on the fractal structure and physical-chemical properties of precursors. Phase transformations which occur during the synthesis of nanosize M-type barium hexaferrite (BHF) were studied as well. The first structural level of precursors' aggregation for mass fractals, the correlation between fractal dimension and precursors' activity during the synthesis of BHF were determined. Synthesis parameters for the precursors with the optimal fractal structure were determined. These data permit an enhancement of the filtration coefficient of the precipitates by a factor of 4-5, obtaining substantial decrease in the temperature required for synthesis of a single-phase BHF, and monodispersed plate-like nanoparticles (60 nm diameter) with the shape anisotropy and good magnetic characteristics (saturation magnetization (M{sub s})=68,7 emu/g and coercitivity (H{sub c})=5440 Oe). - Highlights: > The nanosize M-type BHF obtained by precipitation of hydroxicarbonates technique. > Optimal fractal structure of a precursor for nanosize M-type BHF has been determined. > The precursor precipitated at pH 4.3 allows getting monodisperse particles of BHF.

  3. MWW-type titanosilicate synthesis, structural modification and catalytic applications to green oxidations

    CERN Document Server

    Wu, Peng; Xu, Le; Liu, Yueming; He, Mingyuan

    2013-01-01

    This book provides a comprehensive review of a new generation of selective oxidation titanosilicate catalysts with the MWW topology (Ti-MWW) based on the research achievements of the past 12 years. It gives an overview of the synthesis, structure modification and catalytic properties of Ti-MWW. Ti-MWW can readily be prepared by means of direct hydrothermal synthesis with crystallization-supporting agents, using dual-structure-directing agents and a dry-gel conversion technique. It also can be post-synthesized through unique reversible structure transformation and liquid-phase isomorphous subst

  4. Refined ?-La2S3 and ?-Sm2S3 crystal structures. Relation of structural types of Th3P4 and zircon

    International Nuclear Information System (INIS)

    The diffraction data have been applied to clarify the crystal structures ?-La2S3 and ?-Sm2S3 (a=8.692 and 8.429 A; v=656.8 and 598.2 A3, dsub(meas.)=4.98 and 5.90 g/cm2; dsub(cal)=5.04 and 5.86 g/cm3, Th3P4 structural type. The transition from ZrSiO4 pseudorhombic over the anion packing to the Th3P4 type is shown. It can be presented as an additional filling of double (relatively to zircon) amount of predecahedral cavitations with the simultaneous release of tetrahedrons bound by silicon in zircon

  5. Lack of immunogenicity of ice structuring protein type III HPLC12 preparation administered by the oral route to human volunteers

    DEFF Research Database (Denmark)

    Crevel, R W R; Cooper, K J; Poulsen, Lars K.; Hummelshoj, L; Bindslev-Jensen, Carsten; Burks, A W; Sampson, H A

    2007-01-01

    Before a novel protein can be used in foods, its potential allergenicity must be assessed. In this study, healthy volunteers consumed ice structuring protein (ISP) Type III preparation or a control material 5 days a week for a total of 8 weeks. General measures of health were recorded during the study, and the immunogenicity of the protein was assessed by monitoring the levels of IgG and IgE antibodies specific for ISP Type III. The participants remained in good health throughout the study and d...

  6. Pt-B System Revisited: Pt2B, a New Structure Type of Binary Borides. Ternary WAl12-Type Derivative Borides.

    Science.gov (United States)

    Sologub, Oksana; Salamakha, Leonid; Rogl, Peter; Stöger, Berthold; Bauer, Ernst; Bernardi, Johannes; Giester, Gerald; Waas, Monika; Svagera, Robert

    2015-11-16

    On the basis of a detailed study applying X-ray single-crystal and powder diffraction, differential scanning calorimetry, and scanning electron microscopy analysis, it was possible to resolve existing uncertainties in the Pt-rich section (?65 atom % Pt) of the binary Pt-B phase diagram above 600 °C. The formation of a unique structure has been observed for Pt2B [X-ray single-crystal data: space group C2/m, a = 1.62717(11) nm, b = 0.32788(2) nm, c = 0.44200(3) nm, ? = 104.401(4)°, RF2 = 0.030]. Within the homogeneity range of "Pt3B", X-ray powder diffraction phase analysis prompted two structural modifications as a function of temperature. The crystal structure of "hT-Pt3B" complies with the hitherto reported structure of anti-MoS2 [space group P63/mmc, a = 0.279377(2) nm, c = 1.04895(1) nm, RF = 0.075, RI = 0.090]. The structure of the new "[Formula: see text]T-Pt3B" is still unknown. The formation of previously reported Pt?4B has not been confirmed from binary samples. Exploration of the Pt-rich section of the Pt-Cu-B system at 600 °C revealed a new ternary compound, Pt12CuB6-y [X-ray single-crystal data: space group Im3?, a = 0.75790(2) nm, y = 3, RF2 = 0.0129], which exhibits the filled WAl12-type structure accommodating boron in the interstitial trigonal-prismatic site 12e. The isotypic platinum-aluminum-boride was synthesized and studied. The solubility of copper in binary platinum borides has been found to attain ?7 atom % Cu for Pt2B but to be insignificant for "[Formula: see text]T-Pt3B". The architecture of the new Pt2B structure combines puckered layers of boron-filled and empty [Pt6] octahedra (anti-CaCl2-type fragment) alternating along the x axis with a double layer of boron-semifilled [Pt6] trigonal prisms interbedded with a layer of empty tetrahedra and tetragonal pyramids (B-deficient ?-T[Formula: see text]I fragment). Assuming boron vacancies ordering (space group R3), the Pt12CuB6-y structure exhibits serpentine-like columns of edge-connected boron-filled [Pt6] trigonal prisms running infinitely along the z axis and embedding the icosahedrally coordinated Cu atom. Pt2B, (Pt1-yCuy)2B (y = 0.045), and Pt12CuB6-y (y = 3) behave metallically, as revealed by temperature-dependent electrical resistivity measurements. PMID:26524081

  7. Iron-metallurgy products - Steels for structures and pressure equipment - grades and types. 8. ed.

    International Nuclear Information System (INIS)

    This book reviews french standards on structural steels and pressure equipment in iron-metallurgy products. Standards on concrete reinforcing bars, steel plates for boilers, pressure vessels and other uses as standards on flanges and steel forgings are examined

  8. Special types of FBG and CoaxBG structures for telecommunication and monitoring systems

    Science.gov (United States)

    Morozov, Oleg G.; Nasybullin, Aidar R.; Morozov, Gennady A.; Danilaev, Maxim P.; Zastela, Mikhail Y.; Farkhutdinov, Rafael V.; Faskhutdinov, Lenar M.

    2015-03-01

    The technology of fiber Bragg gratings is used as one of the most applicable technologies for construction of fiber optic sensors and telecommunication systems. Periodic irregular wave resistance located in the guiding waveguide can be regarded as analog of the fiber Bragg grating structure in the field of radio-frequency. Coaxial waveguide can be used as a guide system, so a special case of this structure is the Bragg grating on coaxial cable. Recently, the special structure of sensors were beginning to be used with heterogeneity as a discrete phase ?-shift. Based on the properties analysis of the Bragg reflection characteristics of structures with a phase shift in the optical and microwave range shown advantage of using these devices in measuring systems.

  9. Structural basis of quinolone inhibition of type IIA topoisomerases and target-mediated resistance.

    Science.gov (United States)

    Wohlkonig, Alexandre; Chan, Pan F; Fosberry, Andrew P; Homes, Paul; Huang, Jianzhong; Kranz, Michael; Leydon, Vaughan R; Miles, Timothy J; Pearson, Neil D; Perera, Rajika L; Shillings, Anthony J; Gwynn, Michael N; Bax, Benjamin D

    2010-09-01

    Quinolone antibacterials have been used to treat bacterial infections for over 40 years. A crystal structure of moxifloxacin in complex with Acinetobacter baumannii topoisomerase IV now shows the wedge-shaped quinolone stacking between base pairs at the DNA cleavage site and binding conserved residues in the DNA cleavage domain through chelation of a noncatalytic magnesium ion. This provides a molecular basis for the quinolone inhibition mechanism, resistance mutations and invariant quinolone antibacterial structural features. PMID:20802486

  10. The Preparation and Structural Characterization of Three Structural Types of Gallium Compounds Derived from Gallium (II) Chloride

    Science.gov (United States)

    Gordon, Edward M.; Hepp, Aloysius F.; Duraj. Stan A.; Habash, Tuhfeh S.; Fanwick, Phillip E.; Schupp, John D.; Eckles, William E.; Long, Shawn

    1997-01-01

    The three compounds Ga2Cl4(4-mepy)2 (1),[GaCl2(4-mepy)4]GaCl4x1/2(4-mepy); (2) and GaCl2(4-mepy)2(S2CNEt2); (3) (4-mepy= 4-methylpyridine) have been prepared from reactions of gallium (II) chloride in 4-methylpyridine and characterized by single-crystal X-ray analysis. Small variations in the reaction conditions for gallium(II) chloride can produce crystals with substantially different structural properties. The three compounds described here encompass a neutral gallium(II) dimer in which each gallium is four-coordinate, an ionic compound containing both anionic and cationic gallium complex ions with different coordination numbers and a neutral six-coordinate heteroleptic

  11. Structure of the C-terminal head domain of the fowl adenovirus type 1 short fibre

    International Nuclear Information System (INIS)

    There are more than 100 known adenovirus serotypes, including 50 human serotypes. They can infect all 5 major vertebrate classes but only Aviadenovirus infecting birds and Mastadenovirus infecting mammals have been well studied. CELO (chicken embryo lethal orphan) adenovirus is responsible for mild respiratory pathologies in birds. Most studies on CELO virus have focussed on its genome sequence and organisation whereas the structural work on CELO proteins has only recently started. Contrary to most adenoviruses, the vertices of CELO virus reveal pentons with two fibres of different lengths. The distal parts (or head) of those fibres are involved in cellular receptor binding. Here we have determined the atomic structure of the short-fibre head of CELO (amino acids 201-410) at 2.0 A resolution. Despite low sequence identity, this structure is conserved compared to the other adenovirus fibre heads. We have used the existing CELO long-fibre head structure and the one we show here for a structure-based alignment of 11 known adenovirus fibre heads which was subsequently used for the construction of an evolutionary tree. Both the fibre head sequence and structural alignments suggest that enteric human group F adenovirus 41 (short fibre) is closer to the CELO fibre heads than the canine CAdV-2 fibre head, that lies closer to the human virus fibre heads

  12. Differences in the number of antennal sensory structures of males of three honey bee types

    Directory of Open Access Journals (Sweden)

    STORT A. C.

    1999-01-01

    Full Text Available The number of sensilla campaniformia and sensilla coeloconica + sensilla ampullacea of flagellomeres 2 to 11 of the antennae of three types of males (Italian, African and Africanized was determined by scanning electron microscopy. Comparison of the three male types showed that Italian males did not differ from African males in number of sensilla coeloconica + sensilla ampullacea and that both differed from Africanized males in terms of flagellomere 11. With respect to flagellomeres 3 and 10, Italian males were similar to Africanized males and both differed from African males. No differences between the three male types were detected in the other flagellomeres. In relation to the number of sensilla campaniformia Italian males differed of the African and Africanized males with respect to flagellomere 11.

  13. Enthalpy stabilization of complex oxides Ln4Cu3MoO12 with the YMnO3-type structure

    International Nuclear Information System (INIS)

    Enthalpies of formation of Ln4Cu3MoO12 (Ln = La, Pr, Nd, Sm), featuring the YMnO3 type structure, from simple oxides, bearing in mind changes in cation coordination, were calculated by approximated method of calculation. It is shown that compounds of the structural type are more stable thermochemically than compounds with perovskite-type structure of the same stoichiometry

  14. Structural studies on a non toxic homologue of type II RIPs from bitter gourd: Molecular basis of non toxicity, conformational selection and glycan structure

    Indian Academy of Sciences (India)

    Thyageshwar Chandran; Alok Sharma; M Vijayan

    2015-12-01

    The structures of nine independent crystals of bitter gourd seed lectin (BGSL), a non-toxic homologue of type II RIPS, and its sugar complexes have been determined. The four-chain, two-fold symmetric, protein is made up of two identical two-chain modules, each consisting of a catalytic chain and a lectin chain, connected by a disulphide bridge. The lectin chain is made up of two domains. Each domain carries a carbohydrate binding site in type II RIPS of known structure. BGSL has a sugar binding site only on one domain, thus impairing its interaction at the cell surface. The adenine binding site in the catalytic chain is defective. Thus, defects in sugar binding as well as adenine binding appear to contribute to the non-toxicity of the lectin. The plasticity of the molecule is mainly caused by the presence of two possible well defined conformations of a surface loop in the lectin chain. One of them is chosen in the sugar complexes, in a case of conformational selection, as the chosen conformation facilitates an additional interaction with the sugar, involving an arginyl residue in the loop. The -glycosylation of the lectin involves a plant-specific glycan while that in toxic type H RIPS of known structure involves a glycan which is animal as well as plant specific.

  15. Structural studies on a non-toxic homologue of type II RIPs from bitter gourd: Molecular basis of non-toxicity, conformational selection and glycan structure.

    Science.gov (United States)

    Chandran, Thyageshwar; Sharma, Alok; Vijayan, M

    2015-12-01

    The structures of nine independent crystals of bitter gourd seed lectin (BGSL), a non-toxic homologue of type II RIPs, and its sugar complexes have been determined. The four-chain, two-fold symmetric, protein is made up of two identical two-chain modules, each consisting of a catalytic chain and a lectin chain, connected by a disulphide bridge. The lectin chain is made up of two domains. Each domain carries a carbohydrate binding site in type II RIPs of known structure. BGSL has a sugar binding site only on one domain, thus impairing its interaction at the cell surface. The adenine binding site in the catalytic chain is defective. Thus, defects in sugar binding as well as adenine binding appear to contribute to the non-toxicity of the lectin. The plasticity of the molecule is mainly caused by the presence of two possible well defined conformations of a surface loop in the lectin chain. One of them is chosen in the sugar complexes, in a case of conformational selection, as the chosen conformation facilitates an additional interaction with the sugar, involving an arginyl residue in the loop. The N-glycosylation of the lectin involves a plant-specific glycan while that in toxic type II RIPs of known structure involves a glycan which is animal as well as plant specific. PMID:26648038

  16. La{sub 3}Ir{sub 2} with rhombohedral Er{sub 3}Ni{sub 2}-type structure

    Energy Technology Data Exchange (ETDEWEB)

    Schaefer, Konrad; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2014-10-15

    La{sub 3}Ir{sub 2} is formed upon reaction of the elements at 1273 K in a sealed silica ampoule. The structure was refined from single-crystal X-ray diffractometer data: Er{sub 3}Ni{sub 2}-type structure, R anti 3, a = 895.26(2), c = 1713.01(5) pm, wR = 0.0578, 766 F{sup 2} values, 25 variables. The structure is composed of two simple basic building units: slightly distorted La1 rate at La3{sub 6}La2{sub 2} cubes resembling the tungsten structure and Ir{sub 2} rate at La1{sub 1}La2{sub 2}La3{sub 5} units with an AlB{sub 2}-related coordination (298 pm Ir-Ir in the dumb-bell). Each cube is coordinated by six of the AlB{sub 2} units. The relationship with the U{sub 3}Si{sub 2}-type structure is discussed.

  17. A quick seismic assessment method for jacket type offshore structures by combining push-over and nonlinear time history analyses

    Energy Technology Data Exchange (ETDEWEB)

    Karimiyan, S.; Hosseini, M. [International Inst. of Earthquake Engineering and Seismology, Tehran (Iran, Islamic Republic of); Karimiyan, M. [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Earthquake Eng. Dept., School of Engineering

    2010-07-01

    Several offshore structures are located in seismic regions. In order to upgrade their seismic behaviour, their seismic vulnerability must be evaluated. It is thought that the most reliable type of analysis for seismic evaluation is nonlinear time history analysis (NLTHA), however, it is known to be a very time consuming method. This paper presented a quick procedure by combining the push over analysis (POA) and the NLTHA. The paper discussed both methods in detail. In order to identify the more critical members of the structure, based on the range of their plastic deformations, some POA were first performed. The NLTHA was then performed, focusing on the critical members, to obtain their vulnerability with higher reliability. An offshore structure of jacket type, installed in the Lavan oil field in the Persian Gulf in 1970, was also considered in order to demonstrate the efficiency of the proposed method. It was concluded from the numerical results that combining POA and NLTHA was a quick and reliable seismic evaluation method. The results demonstrated that although the vulnerability of the jacket structure was not very high, the level of damage was not the same for different members, and was dependent on their location in the structure and also its geometric orientation and load bearing situation. 6 refs., 1 tab., 8 figs.

  18. Structural evolution of early-type galaxies to z = 2.5 in CANDELS

    OpenAIRE

    Chang, Y-Y; van der Wel, A; Rix, H-W; Holden, B; Bell, EF; McGrath, EJ; Wuyts, S; Häussler, B; Barden, M; Faber, SM; M. Mozena; Ferguson, HC; Y. Guo; A. Galametz; Grogin, NA

    2013-01-01

    Projected axis ratio measurements of 880 early-type galaxies at redshifts 1 < z < 2.5 selected from CANDELS are used to reconstruct and model their intrinsic shapes. The sample is selected on the basis of multiple rest-frame colors to reflect low star-formation activity. We demonstrate that these galaxies as an ensemble are dust-poor and transparent and therefore likely have smooth light profiles, similar to visually classified early-type galaxies. Similar to their present-day counterparts, t...

  19. Structure and function of collectins: humoral C-type lectins with collagenous regions

    DEFF Research Database (Denmark)

    Holmskov, Uffe Laurits; Jensenius, Jens Christian

    1993-01-01

    Collectins are a family of C-type lectins with collagenous regions. Five such lectins have now been described: Lung surfactant protein A and D (SP-A and SP-D), and the plasma proteins, conglutinin, mannan-binding protein (MBP), and CL-43. They are composed of trimeric subunits containing a collagenous section and a C-terminal globular carbohydrate-recognizing domain containing the 14 invariant amino acids characteristic of the C-type lectins. The complete molecules of MBP and SP-A are composed o...

  20. On Methods of Establishing Design Diagrams for Structural Integrity of Slender Complex Types of Breakwater Armour Units

    DEFF Research Database (Denmark)

    Burcharth, Hans F.; Howell, Gary J.

    1988-01-01

    .The first methods for the estimation of the structural integrity of the slender type of armour units appeared few years ago. A method based on similarity consideration and full scale impact tests was developed for units mainly exposed to impact loads (Burcharth 1981). Instrumented small scale model armour...... other researchers, it might be a frame for a uniform presentation of results. Without a uniformity it will take much longer before the oncoming data on structural integrity can be made useful through contributions to the future data bank which will be needed as a design tool....

  1. An effective Skyrme-type interaction for the calculation of nuclear structures of the whole mass table

    International Nuclear Information System (INIS)

    The Hartree-Fock-Bogolyubov formalism is extended for 3 body interactions and applied to spherical nuclei. The structure of the proposed extension of the Skyrme-type interaction is given, together with the analytical expression of the corresponding Hartree-Fock differential equation. The Skyrme-force parameters are modified in order to be able to reproduce the ground state properties. The problem of the spin-stability of the proposed interaction is treated. The Skyrme-interaction is applied as particle-hole interaction and saturation properties are studied. Structure of the charge, neutron density distributions and changes introduced by adding protons or neutrons are treated. (MDC)

  2. Al-doping effect on the structural and physical properties of delafossite-type oxide CuCrO2

    International Nuclear Information System (INIS)

    The structure, Raman spectroscopy, magnetization, and dielectric properties of delafossite-type oxide CuCr1-xAlxO2 have been characterized. It was found that Al substitution generates an anisotropic effect on the structure, besides magnetic dilution. The temperature dependence of all samples exhibits paramagnetic behavior at high temperature. Above x=0.2 the ferromagnetic transition at 120 K disappears. It is argued that Al substitution destabilizes the antiferromagnetic order of Cr3+ ions and modulates the spin configuration, leading to a weak ferromagnetism. The coupling between the magnetic order and ferroelectric order is also characterized.

  3. Crystal structures of wild-type and mutated cyclophilin B that causes hyperelastosis cutis in the American quarter horse

    Directory of Open Access Journals (Sweden)

    Boudko Sergei P

    2012-11-01

    Full Text Available Abstract Background Hyperelastosis cutis is an inherited autosomal recessive connective tissue disorder. Affected horses are characterized by hyperextensible skin, scarring, and severe lesions along the back. The disorder is caused by a mutation in cyclophilin B. Results The crystal structures of both wild-type and mutated (Gly6->Arg horse cyclophilin B are presented. The mutation neither affects the overall fold of the enzyme nor impairs the catalytic site structure. Instead, it locally rearranges the flexible N-terminal end of the polypeptide chain and also makes it more rigid. Conclusions Interactions of the mutated cyclophilin B with a set of endoplasmic reticulum-resident proteins must be affected.

  4. Changes in the structural and biochemical composition of the arterial wall in type 2 diabetes patients

    DEFF Research Database (Denmark)

    RØrdam Preil, Simone

    2015-01-01

    Arteriel stivhed er et normalt aldersbetinget fænomen. Hos patienter med type 2 diabetes synes udviklingen af arteriel stivhed accelereret, hvilket kunne være årsagen til den forøgede incidens af kardiovaskulære sygdomme hos disse patienter. Ophobningen af kollagen og/eller nedbrydningen af elastin i den diabetiske arterievæg kunne ligge til grund for den arterielle stivhed hos patienter med type 2. Disse strukturelle ændringer mangler dog at blive undersøgt i humane arterier. I det første studie var formålet derfor at identificere histologisk forandringer i den strukturelle sammensætning af ikke-atherosclerotisk arterievæv fra patienter med og uden type 2 diabetes. Arteriesnittene fra mammaria arterierne blev farvet for makrofager, elastin, kollagen og ? smooth muscle actin, hvorefter vi målte området for kollagen og elastin og antallet af celler, der farves for ? smooth muscle actin, ved hjælp af histomorphometrisk analyser i lagene tunica intima, media og de luminale 30 ?m af adventitia. De histologiske undersøgelser viste, at der ikke var nogen makrofag infiltreringer i de tre lag, og at der ikke var nogen forskel på de elastin farvede områder. Dog var antallet af celler i adventitia laget signifikant lavere hos patienter med diabetes, og kollagen farvningen viste et større farvet område i intima og media lagene hos type 2 diabetes patienter end for patienterne uden diabetes. Ydermere forholder det sig således, at størstedelen af patienter med type 2 diabetes bliver behandlet med medikamentet metformin. Udover at have en glukose sænkende effekt menes det ligeledes at påvirke det kardiovaskulære system positivt. For at undersøge hvilke komponenter af arterievæggen metformin influerer på, besluttede vi os for at lave en kvantitative proteom analyse i det andet studie. Studie II og studie I er foretaget på det samme patient materiale. Denne gang blev der brugt et enkelt vævssnit til proteom undersøgelsen. Resultaterne fra dette forsøg viste, at mængden af kollagen type IV blandt andet var forøget hos patienter med type 2 diabetes sammenlignet med patienter uden diabetes. De viste ligeledes, at metformin havde en normaliserende effekt på den arterielle protein sammensætning hos patienter med type 2 diabetes. For at se nærmere på den accelererede udvikling af arteriel stivhed hos patienter med type 2 diabetes besluttede vi at undersøge rygningens og calpain-1´s betydning for elastin nedbrydningen. Flere studier har vist, at rygning påvirker den arterielle stivhed, mens andre studier peger mod, at cystein proteasen calpian-1 øger mængden af matrix metalloproteinasen 2 (MMP-2), som nedbryder bl.a. elastin. Vores hypotese i studie III gik både ud på, at calpain-1 kunne være forøget hos patienter med type 2 diabetes, hvorved den vil føre til forøget kollagen indhold, forøget MMP-2 og reduceret elastin i arterierne, og at rygning kunne have en indvirkning på mængden af disse molekyler. Niveauet af MMP-2, calpain-1 og actin ? smooth muscle blev målt ved hjælp af western blotting i mammaria arterier fra patienter medog uden diabetes. De tilovers blivende vævs rester blev derefter hydrolyseret for at måle elastin fragmentet desmosine med liquid chromatography og mass spectrometry (LC-MS), mens kollagen indholdet blev målt ved brug af et hydroxyproline assay. Resultaterne viste, at diabetes ikke påvirkede mængden af calpain-1, MMP-2, desmosine og hydroxyproline i den human arterie væg, mens mængden af desmosine var nedsat i arterier fra ryger og tidligere rygere sammenlignet med ikke rygere. Et andet protein der ligeledes er involveret i den strukturelle sammensætning af arterievæggen er lysyl oxidase (LOX), som krydsbinder henholdsvis elastin og kollagen. Forskellige undersøgelser har vist, at diabetes kunne øge mængden af LOX, hvilket ligeledes er blevet vist for MMP-2. Hvis dette skulle være sandt, ville vi antage at LOX kunne øge krydsbindingen af kollagen, mens MMP-2 øgede nedbrydningen af elastin i patienter med type 2 diabetes. Derfor bestemte vi os i

  5. Internal Materials and structural Investigations of C-type Asteroid using carry-on Impactor by Hayabusa-2

    Science.gov (United States)

    Okamoto, Chisato; Takagi, Yasuhiko; Yano, Hajime; Saiki, Takanao; Tsuda, Yuichi; Yoshikawa, Makoto

    Recent explorations carried out by spacecraft provided important information regarding the physical properties of asteroids, particularly their bulk density and surface morphology. For example, Hayabusa spacecraft launched in 2003 investigated 25143 Itokawa, an S-type asteroid, after it arrived at 25143 Itokawa in September, 2005. Hayabusa has made a large amount of scientific discoveries and technological achievements during its stay, and left Itokawa in December, 2005 in order to deliver us the surface material. Observations by the Hayabusa spacecraft revealed that 25143 Itokawa has a rubble-pile structure owing to the re-accumulation of disrupted impact fragments. Itokawa has a high porosity (˜40%), probably because of the macro-porosity among the disrupted fragments. Based on such previous observations, it is proposed that the internal structures of asteroids have diversity in bulk densities and porosities. However, we have no direct observational data for the internal structure and materials. It is possible that the surface materials of small bodies seriously damaged by cosmic ray exposure. Thus, we should investigate the chemical and physical properties of the internal material. Also, we need to investigate the internal structure in order to understand the formation history. Now we are planning the study of the next asteroid exploration mission in 2014. From the point of the scientific objective, 1999 JU3, a C-type asteroid, was chosen as the target; C-type asteroids are considered to have more primitive material such as organic matters in comparison to Itokawa, an S-type asteroid. The spacecraft called as Hayabusa-2 basically follows the design of Hayabusa spacecraft. But, we will develop some new equipment to investigate the C-type asteroid, especially a carry-on impactor for the internal materials and structural investigations. The impactor will be shoot on the asteroid at ˜2km/s in order to expose the internal materials via crater formation and induce seismicity by the impact. The size and weight of impactor is restricted because the possible payload mass of Hayabusa-2 is not so large; its system should be very simple. If we use the rocket motor, the acceleration distance becomes large and the guidance system is necessary for the accurate impact. Additionally, the impact will cause a serious contamination by mechanical mixture of the impactor into the asteroid sample during crater formation process. Hence we adopt powerful explosive to accelerate the metal impact head and we shorten the accelerate time (less than 1 ms). In the presentation we will give an overview of a C-type asteroid investigation using the small carry-on impactor of Hayabusa-2.

  6. On the prolongation structures of Petrov type III vacuum spacetime equations

    OpenAIRE

    E. O. Ifidon

    2009-01-01

    The universal covering symmetry algebra of the Robinson-Trautman equations of Petrov Type III is shown to include the infinite-dimensional affine Kac-Moody algebra A_1 as a prolongation algebra. This algebra has slower growth than the contragradient algebra K_2 obtained previously for this equation.

  7. A correlation between redox behaviour of Fischer-type carbene complexes and their structure and reactivity.

    Czech Academy of Sciences Publication Activity Database

    Hoskovcová, I.; Dvo?ák, D.; Ludvík, Ji?í; Záliš, Stanislav

    Bratislava : Slovak Technical University Press, 2007 - (Melník, M.; Šima, J.; Tatarko, M.), s. 1-15 R&D Projects: GA ?R GA203/04/0487 Institutional research plan: CEZ:AV0Z40400503 Keywords : Fischer-type carbene complexes * correlation * electrochemical measurements Subject RIV: CG - Electrochemistry

  8. Structural Evolution of Early-type Galaxies to z=2.5 in CANDELS

    CERN Document Server

    Chang, Yu-Yen; Rix, Hans-Walter; Holden, Bradford; Bell, Eric F; McGrath, Elizabeth J; Wuyts, Stijn; Häußler, Boris; Barden, Marco; Faber, S M; Mozena, Mark; Ferguson, Henry C; Guo, Yicheng; Galametz, Audrey; Grogin, Norman A; Kocevski, Dale D; Koekemoer, Anton M; Dekel, Avishai; Huang, Kuang-Han; Hathi, Nimish P; Donley, Jennifer

    2013-01-01

    Projected axis ratio measurements of 880 early-type galaxies at redshifts 11 early-type galaxies show a variety of intrinsic shapes; even at a fixed mass, the projected axis ratio distributions cannot be explained by random projection of a set of galaxies with very similar intrinsic shapes. However, a two-population model for the intrinsic shapes, consisting of a triaxial, fairly round population, combined with a flat (c/a~0.3) oblate population, adequately describes the projected axis ratio distributions of both present-day and z>1 early-type galaxies. We find that the proportion of oblate vs. triaxial galaxies depends both on the galaxies stellar mass, and - at a given mass - on redshift. For present-day and z1 this trend is much weaker over the mass range explored here (10^101, compared to 0.20+-0.02 at z~0.1. In contrast, the oblate fraction among low-mass early-type galaxies (log(M*/M_sun)1 to 0.72+-0.06 at z=0. [Abridged

  9. SMS crew station (C and D panels and forward structures). CEI part 1: Detail specification, type 1 data

    Science.gov (United States)

    1976-01-01

    Established are the requirements for performance, design, test and qualification of one type of equipment identified as SMS C&D panels and forward structures. This CEI is used to provide all hardware and wiring necessary for the C&D panels to be properly interfaced with the computer complex/signal conversion equipment (SCE), crew station, and software requirements as defined in other CEI specifications.

  10. [Dynamics of the histological structure and function of the skin during adaptation of Angler cattle of various constitutional types].

    Science.gov (United States)

    Shalimov, N A; Katsy, G D

    1989-01-01

    Skin structure of the Angler cattle of different types of constitution and genetic-ecological generations has been studied. It is stated that gradual skin thickening promoting protection of the organism from overheating is observed in hot climate in the south of the Ukraine. Intrabreed variability of some skin parameters is revealed, that permits a breeding improvement of adaptability in the masticatory cows. PMID:2815327

  11. An Examination of the Influence of Organizational Structure Types and Management Levels on Knowledge Management Practices in Organizations

    OpenAIRE

    Jen S. Steiger; Khalid Ait Hammou; Md Hasan Galib

    2014-01-01

    The purpose of this study was to investigate the difference between organizational structure types, andmanagement levels, in terms of perceived levels of knowledge management practices within organizations. Datawere collected from a sample of 155 individuals employed in San Diego County by way of a web-based survey,and were analyzed using analysis of variance (ANOVA). The results of the study indicate that the knowledgemanagement practices of knowledge transfer, information filtering, and kno...

  12. STRUCTURAL EVOLUTION OF EARLY-TYPE GALAXIES TO z = 2.5 IN CANDELS

    International Nuclear Information System (INIS)

    Projected axis ratio measurements of 880 early-type galaxies at redshifts 1 1 early-type galaxies show a variety of intrinsic shapes; even at a fixed mass, the projected axis ratio distributions cannot be explained by the random projection of a set of galaxies with very similar intrinsic shapes. However, a two-population model for the intrinsic shapes, consisting of a triaxial, fairly round population, combined with a flat (c/a ? 0.3) oblate population, adequately describes the projected axis ratio distributions of both present-day and z > 1 early-type galaxies. We find that the proportion of oblate versus triaxial galaxies depends both on the galaxies' stellar mass, and—at a given mass—on redshift. For present-day and z 1, this trend is much weaker over the mass range explored here (1010 */M? 11), because the oblate fraction among massive (M* ? 1011 M?) was much higher in the past: 0.59 ± 0.10 at z > 1, compared to 0.20 ± 0.02 at z ? 0.1. When combined with previous findings that the number density and sizes of early-type galaxies substantially increase over the same redshift range, this can be explained by the gradual emergence of merger-produced elliptical galaxies, at the expense of the destruction of pre-existing disks that were common among their high-redshift progenitors. In contrast, the oblate fraction among low-mass early-type galaxies (log (M*/M?) 1 to 0.72 ± 0.06 at z = 0. We speculate that this lower incidence of disks at early cosmic times can be attributed to two factors: low-mass, star-forming progenitors at z > 1 were not settled into stable disks to the same degree as at later cosmic times, and the stripping of gas from star-forming disk galaxies in dense environments is an increasingly important process at lower redshifts

  13. First-principles molecular spin dynamics study on the magnetic structure of Mn-based alloys with Cu3Au-type crystal structure

    Science.gov (United States)

    Uchida, T.; Kakehashi, Y.; Kimura, N.

    2016-02-01

    The magnetic and electronic structures of Mn3Pt and Mn3Rh, which are three-dimensional frustrated itinerant magnets with a Cu3Au-type crystal structure, have been investigated by means of the first-principles Molecular Spin Dynamics (MSD) method. The theory is based on the first-principles tight-binding linear muffin-tin orbital Hamiltonian combined with the functional integral method and the isothermal MSD technique, and allows us to determine automatically the magnetic structures of itinerant magnets at finite temperatures. The MSD calculations using a self-consistent site-dependent effective medium show that below the Néel temperature Mn3Pt with fixed crystal structure (Cu3Au structure) and volume exhibits a second-order transition from a triangular structure to another noncollinear phase with increasing temperature. Mn3Rh, on the other hand, shows no sign of a phase transition up to the Néel temperature. We found that the Mn-Eg DOS peak, which is responsible for the ferromagnetic couplings among the second nearest-neighbor Mn local moments, develops at the Fermi energy (EF) around 350 K for Mn3Pt, while the peak development for Mn3Rh occurs with increasing temperature slightly above EF.

  14. Structure of Glycerol Dehydratase Reactivase: A New Type of Molecular Chaperone

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Der-Ing; Reiss, Lisa; Turner, Jr., Ivan; Dotson, Garry (Dupont)

    2010-03-08

    The function of glycerol dehydratase (GDH) reactivase is to remove damaged coenzyme B{sub 12} from GDH that has suffered mechanism-based inactivation. The structure of GDH reactivase from Klebsiella pneumoniae was determined at 2.4 {angstrom} resolution by the single isomorphous replacement with anomalous signal (SIR/AS) method. Each tetramer contains two elongated 63 kDa {alpha} subunits and two globular 14 kDa {beta} subunits. The {alpha} subunit contains structural features resembling both GroEL and Hsp70 groups of chaperones, and it appears chaperone like in its interactions with ATP. The fold of the {beta} subunit resembles that of the {beta} subunit of glycerol dehydratase, except that it lacks some coenzyme B12 binding elements. A hypothesis for the reactivation mechanism of reactivase is proposed based on these structural features.

  15. Structure and mechanism of Zn2+-transporting P-type ATPases

    DEFF Research Database (Denmark)

    Wang, Kaituo; Sitsel, Oleg; Meloni, Gabriele; Autzen, Henriette Elisabeth; Andersson, Magnus; Klymchuk, Tetyana; Nielsen, Anna Marie; Rees, Douglas C; Nissen, Poul; Gourdon, Pontus Emanuel

    2014-01-01

    A) are crucial for cellular redistribution and detoxification of Zn(2+) and related elements. Here we present crystal structures representing the phosphoenzyme ground state (E2P) and a dephosphorylation intermediate (E2·Pi) of ZntA from Shigella sonnei, determined at 3.2 Å and 2.7 Å resolution......, respectively. The structures reveal a similar fold to Cu(+)-ATPases, with an amphipathic helix at the membrane interface. A conserved electronegative funnel connects this region to the intramembranous high-affinity ion-binding site and may promote specific uptake of cellular Zn(2+) ions by the transporter. The...... E2P structure displays a wide extracellular release pathway reaching the invariant residues at the high-affinity site, including C392, C394 and D714. The pathway closes in the E2·Pi state, in which D714 interacts with the conserved residue K693, which possibly stimulates Zn(2+) release as a built...

  16. Dynamic structural analysis of a head assembly for a large loop-type LMFBR

    International Nuclear Information System (INIS)

    An investigation is presented on the dynamic structural response of the primary vessel's head closure to slug impact loadings generated from a 1000 MJ source term. The reference reactor considered was designed in a loop configuration. The head structure consisted of a deck and a triple rotatable plug assembly. Two designs were considered for the deck structure: a reference design and an alternate design. The reference deck was designed as a single flat annular plate. For the alternate design, the deck plate was reinforced by adding an extender cylinder with a flange and flanged webs between the deck-plate and cylinder. The investigation showed that the reference design cannot maintain containment integrity when subjected to slug loading generated by a 1000 MJ source term. It was determined that the head deformed excessively

  17. Design of an Improved Type Rotary Inductive Coupling Structure for Rotatable Contactless Power Transfer System

    Directory of Open Access Journals (Sweden)

    Lee Jia-You

    2015-01-01

    Full Text Available This paper is aimed at analyzing the rotary inductive coupling structure of contactless rotary transformer. The main feature of the proposed rotatable contactless power transfer system is which winding is coaxial-interlayered for improving the magnetic coupling capability. There is no ferrite core used in the secondary-side of the rotary inductive coupling structure, this helps to ease the exerted force that is stress by the secondary-side on spindle. In order to verify the feasibility of the proposed contactless power transfer system for rotary applications, an inductive powered rotary machinery and the control system have been integrated. The experimental results show that the maximum power transfer efficiency of the proposed rotary inductive coupling structure is about 94.8%. The maximum output power received in the load end is 1030 W with transmission efficiency of 88%.

  18. AN INVESTIGATION OF THE TYPE M MORPHOLOGICAL STRUCTURE OF IC59: A NEW MODEL FOR BRIGHT RIM CLOUDS?

    International Nuclear Information System (INIS)

    We report the results from a smoothed particle hydrodynamics simulation designed to model recent observational data on the nebula and Bright Rim Cloud IC59. We further examine, in the context of radiative-driven implosion (RDI) models, the possible formation mechanisms of the morphological structure of IC59. The results of the simulation reveal the existence of a new, fourth morphological state for Bright Rim Clouds (BRCs)-which we propose to call a Type M BRC morphology. We discuss the necessary conditions for the appearance of Type M BRCs, based on analytical and numerical simulations. The simulated physical properties from our model are consistent with the available observations of IC59. We further show that the prospect of RDI triggered star formation in all Type M BRCs is not supported by the simulations.

  19. Types of tectonic structures, sedimentary volcanogenetic formations of a mantle, favourable processes for exogenetic and polygenetic uranium deposits formation

    International Nuclear Information System (INIS)

    Factors, affecting mineralization processes are considered. Characteristic features of uranium-bearing provinces are as follows: the presence of crust of continental type; deep-seated tectonic structures-rises and saggings, roofs, gneiss domes, rift zones and transform fractures; specialization for uranium of sedimentary and magmatic formations; the presence of manifestation regions of deep thermal and gaseous flow, etc. In uranium-bearing provinces territories favourable for the manifestation of different types of uranium mineralization: metamorphogenetic, polygenetic and exogenetic ones, are singled out. Different epochs of uranium ore formation are established. In sedimentary masses tectonic regime and climate are of special importance, and for epigenetic deposits, formed with an aid of underground waters-hydrogeological conditions. In the limits of the main structural elements of the Earth crust and geotectonic structures of higher orders the following types of sedimentary and volcanic formations can be singled out: 1-formations with exogenous uranium mineralization; 2-formations, accumulated in the epochs of epigenous ore formation; 3-formations fav ourable for epigenous uranium deposit formation; 4-formations unfavourable for the formation and localization of uranium mineralization

  20. Structure of the VipA/B Type VI Secretion Complex Suggests a Contraction-State-Specific Recycling Mechanism

    Directory of Open Access Journals (Sweden)

    Sebastian Kube

    2014-07-01

    Full Text Available The bacterial type VI secretion system is a multicomponent molecular machine directed against eukaryotic host cells and competing bacteria. An intracellular contractile tubular structure that bears functional homology with bacteriophage tails is pivotal for ejection of pathogenic effectors. Here, we present the 6 Å cryoelectron microscopy structure of the contracted Vibrio cholerae tubule consisting of the proteins VipA and VipB. We localized VipA and VipB in the protomer and identified structural homology between the C-terminal segment of VipB and the tail-sheath protein of T4 phages. We propose that homologous segments in VipB and T4 phages mediate tubule contraction. We show that in type VI secretion, contraction leads to exposure of the ClpV recognition motif, which is embedded in the type VI-specific four-helix-bundle N-domain of VipB. Disaggregation of the tubules by the AAA+ protein ClpV and recycling of the VipA/B subunits are thereby limited to the contracted state.