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1

Polarization phenomena in romboedric structures of NASICON  

International Nuclear Information System (INIS)

In given article peculiarities of polarization phenomena in Na3Cr2(PO4)3 of structured NASICON type are considered. On analysis base features and parameters of the process relaxational polarization in joining the structured NASICON type is revealed. Factors explaining relaxational polarization in ?'-dielectric and in ?-conducting phase of join from given structured type are presented. (author)

2

Evidence of a relation between structural defects and phase transitions in NASICON type compounds  

Science.gov (United States)

X-ray scattering and conventional structure determinations of NASICON type compounds reveal the existence of two phase transitions. The first one corresponds to a change of correlations between off-centered octahedral atoms and the second to an occupation transfer between sodium sites. The order of these transitions and associated thermal effects are influenced by the nature of octahedral atoms, the non stoichiometry and structural defects.

Boilot, J. P.; Collin, G.; Comès, R.

1983-01-01

3

Crystal structure investigation of ternary molybdate of potassium - manganese - zirconium with the Nasicon type structure  

International Nuclear Information System (INIS)

The composition and crystal structure of the K0.52(Mn0.47Zr0.45)2(MoO4)3 ternary molybdate are clarified according to the X-ray data. The trigonal elementary cell metrics constitutes: a = b = 9.474(1), c = 24.371(4) A, Z =6, ?cal = 3.337 g/cm3, sp. gr. R3-barc. The crystalline structure constitutes the three-dimensional mixed skeleton from the (Mn, Zr)O6 octahedrons and MoO4 tetrahedrons with common oxygen apexes, in the large channels whereof the potassium atoms are positioned and it is related to the Nasicon structural type

4

Trivalent praseodymium ion conducting solid electrolyte composite with NASICON type structure  

International Nuclear Information System (INIS)

New trivalent praseodymium ion (Pr3+) conducting solid electrolyte composites, (PrxZr1-x)4/(4-x)Nb(PO4)3 (0.05?x?0.3)+NbPO5, were successfully developed by selecting the NASICON type structure as the mother structure candidate. The 94±5% praseodymium ion in the composites was identified to hold the trivalent state by effective magnetic moment measurements and the pure Pr3+ ion conduction in the composite solid was demonstrated both by ac conductivity measurements in various oxygen partial pressures and by dc electrolytes

5

Trivalent praseodymium ion conducting solid electrolyte composite with NASICON type structure  

Energy Technology Data Exchange (ETDEWEB)

New trivalent praseodymium ion (Pr{sup 3+}) conducting solid electrolyte composites, (Pr{sub x}Zr{sub 1-x}){sub 4/(4-x)}Nb(PO{sub 4}){sub 3} (0.05{<=}x{<=}0.3)+NbPO{sub 5}, were successfully developed by selecting the NASICON type structure as the mother structure candidate. The 94{+-}5% praseodymium ion in the composites was identified to hold the trivalent state by effective magnetic moment measurements and the pure Pr{sup 3+} ion conduction in the composite solid was demonstrated both by ac conductivity measurements in various oxygen partial pressures and by dc electrolytes.

Hasegawa, Y.; Tamura, S.; Imanaka, N.; Adachi, G.; Takano, Y.; Tsubaki, T.; Sekizawa, K

2004-07-28

6

LiTi 2(PO 4) 3 with NASICON-type structure as lithium-storage materials  

Science.gov (United States)

LiTi 2(PO 4) 3 with a Na + superionic conductor (NASICON)-type structure is prepared by a two-step solid-state reaction. X-ray diffraction (XRD) confirms that the LiTi 2(PO 4) 3 compound has a NASICON structure, i.e. rhombohedral (space group: R3 c). It is found that lithium can be electrochemically inserted into the LiTi 2(PO 4) 3 structure, with a maximum intake of 5.2 mol of lithium per mole of LiTi 2(PO 4) 3 compound, and that [PO 4] tetrahedra can participate in the redox reaction. This corresponds to a lithium-storage capacity of 360 mAh g -1. The kinetic parameters of lithium insertion in LiTi 2(PO 4) 3 NASICON are determined by means of ac impedance technique. The charge-transfer resistance ( RCT) and exchange current density ( i0) are invariable regardless of the state of lithium insertion. This is associated with the unique structure characteristics of the NASICON skeleton. By contrast, the diffusion coefficient, DLi of lithium varies with the state of lithium insertion. The value of DLi is in the range 1.4×10 -11 to 1.2×10 -9 m 2 s -1, which is much higher than for other intercalation materials.

Wang, G. X.; Bradhurst, D. H.; Dou, S. X.; Liu, H. K.

7

New trivalent ion conducting solid electrolyte with the NASICON type structure  

International Nuclear Information System (INIS)

New trivalent ion conducting solid electrolytes with NASICON type structure, [(Ce1-xLax)0.1Zr0.9]40/39Nb(PO4)3, were successfully developed and their ion conducting behaviors were investigated. Among the [(Ce1-xLax)0.1Zr0.9]40/39Nb(PO4)3 series prepared, the highest ion conductivity was obtained for [(Ce1-xLax)0.1Zr0.9]40/39Nb(PO4)3 (x=0.8). The trivalent ion conductivity was approximately four times higher than that of cerium (Ce3+) ion conducting (Ce0.1Zr0.9)40/39Nb(PO4)3, and the values exceeded the region of the representative divalent oxide anion conductors such as yttria stabilized zirconia (YSZ) and calcia stabilized zirconia (CSZ) at temperatures below 500 deg. C

8

New trivalent ion conducting solid electrolyte with the NASICON type structure  

Energy Technology Data Exchange (ETDEWEB)

New trivalent ion conducting solid electrolytes with NASICON type structure, [(Ce{sub 1-x}La{sub x}){sub 0.1}Zr{sub 0.9}]{sub 40/39}Nb(PO{sub 4}){sub 3}, were successfully developed and their ion conducting behaviors were investigated. Among the [(Ce{sub 1-x}La{sub x}){sub 0.1}Zr{sub 0.9}]{sub 40/39}Nb(PO{sub 4}){sub 3} series prepared, the highest ion conductivity was obtained for [(Ce{sub 1-x}La{sub x}){sub 0.1}Zr{sub 0.9}]{sub 40/39}Nb(PO{sub 4}){sub 3} (x=0.8). The trivalent ion conductivity was approximately four times higher than that of cerium (Ce{sup 3+}) ion conducting (Ce{sub 0.1}Zr{sub 0.9}){sub 40/39}Nb(PO{sub 4}){sub 3}, and the values exceeded the region of the representative divalent oxide anion conductors such as yttria stabilized zirconia (YSZ) and calcia stabilized zirconia (CSZ) at temperatures below 500 deg. C.

Hasegawa, Y.; Tamura, S.; Imanaka, N.; Adachi, G

2004-10-06

9

Synthesis and properties of Nasicon-type materials  

International Nuclear Information System (INIS)

Various composition of Na1+xSixZr2P3-xO12 (x from 1.6 to 2.4), Y-doped Nasicon (Na1+x+yZr2-yYySixP3-xO12, Na1+xZr2-yYySixP3-xO12-y, where x = 2, y = 0.12) and Fe-doped Nasicon (Na3Zr2/3Fe4/3P3O12) were prepared by coprecipitating. Differential thermal analysis (DTA), thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and impedance spectroscopy (IS) were used as experimental techniques.In order to obtain Nasicon materials free from ZrO2 admixture, the calcination of coprecipitates must be carried out in proper thermal conditions. The results of DTA, TG and XRD measurements allowed us to propose the best calcination conditions (to obtain mainly Nasicon phases - monoclinic or rhombohedral, depending on composition). Nasicon-type materials exhibit monoclinic to rhombohedral reversible structural transition, at transition temperature depending on composition (x). The influence of dopants was also studied. The DSC measurements in the temperature range RT-300 deg. C allowed us to determine the temperatures of this structural transition in the case of Na1+xSixZr2P3-xO12, and Y-doped Nasicon. In the cas>12, and Y-doped Nasicon. In the case of Fe-doped materials this transition was not detected.Additionally, the correlation between the composition, microstructure and electrical properties was studied

10

Synthesis and properties of Nasicon-type materials  

Energy Technology Data Exchange (ETDEWEB)

Various composition of Na{sub 1+x}Si{sub x}Zr{sub 2}P{sub 3-x}O{sub 12} (x from 1.6 to 2.4), Y-doped Nasicon (Na{sub 1+x+y}Zr{sub 2-y}Y{sub y}Si{sub x}P{sub 3-x}O{sub 12}, Na{sub 1+x}Zr{sub 2-y}Y{sub y}Si{sub x}P{sub 3-x}O{sub 12-y}, where x = 2, y = 0.12) and Fe-doped Nasicon (Na{sub 3}Zr{sub 2/3}Fe{sub 4/3}P{sub 3}O{sub 12}) were prepared by coprecipitating. Differential thermal analysis (DTA), thermogravimetry (TG), differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and impedance spectroscopy (IS) were used as experimental techniques.In order to obtain Nasicon materials free from ZrO{sub 2} admixture, the calcination of coprecipitates must be carried out in proper thermal conditions. The results of DTA, TG and XRD measurements allowed us to propose the best calcination conditions (to obtain mainly Nasicon phases - monoclinic or rhombohedral, depending on composition). Nasicon-type materials exhibit monoclinic to rhombohedral reversible structural transition, at transition temperature depending on composition (x). The influence of dopants was also studied. The DSC measurements in the temperature range RT-300 deg. C allowed us to determine the temperatures of this structural transition in the case of Na{sub 1+x}Si{sub x}Zr{sub 2}P{sub 3-x}O{sub 12}, and Y-doped Nasicon. In the case of Fe-doped materials this transition was not detected.Additionally, the correlation between the composition, microstructure and electrical properties was studied.

Ignaszak, A. [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Cracow (Poland)]. E-mail: ignaszak@uci.agh.edu.pl; Pasierb, P. [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Cracow (Poland); Gajerski, R. [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Cracow (Poland); Komornicki, S. [Faculty of Materials Science and Ceramics, AGH University of Science and Technology, al. Mickiewicza 30, 30-059 Cracow (Poland)

2005-02-01

11

Dipole ordering and disordering in the NASICON-like structures of Na3Sc2(PO4)3 type  

International Nuclear Information System (INIS)

In the given article the role a M-cations in creation of conductive and dielectric properties of dipole ordered phase in substance of Na3M2(PO4)3 where M =Sc, Cr, Fe and also solid solutions of Na3Sc2(1-x)M2x(PO4)3, where M=Al, Ga, Cr, Fe, Yb, Ho, Y of NASICON-type are studied. In this substance the temperature of phase transition ??? decreases with increases of ionic radius of M-cations, as well as in solid solution of T??? connection back inversely proportional with ionic radius of M'-cations dopants are found. The crystal framework of this typical subject deformations, as under influence of hydrostatic pressure, so and by means of charge size of M-cations are concluded. Besides, the connection are found between the conductive and dielectric properties of these substances and sizes of M-cations. The change conductive and dielectric properties of connections with infringement regulation of initial rhombohedral crystal framework structures {[Sc2(PO4)3]3-}3? in result of assistant M?Sc are found. (author)

12

Low-potential sodium insertion in a NASICON-type structure through the Ti(III)/Ti(II) redox couple.  

Science.gov (United States)

We report the direct synthesis of powder Na3Ti2(PO4)3 together with its low-potential electrochemical performance and crystal structure elucidation for the reduced and oxidized phases. First-principles calculations at the density functional theory level have been performed to gain further insight into the electrochemistry of Ti(IV)/Ti(III) and Ti(III)/Ti(II) redox couples in these sodium superionic conductor (NASICON) compounds. Finally, we have validated the concept of full-titanium-based sodium ion cells through the assembly of symmetric cells involving Na3Ti2(PO4)3 as both positive and negative electrode materials operating at an average potential of 1.7 V. PMID:23421416

Senguttuvan, P; Rousse, G; Arroyo y de Dompablo, M E; Vezin, Hervé; Tarascon, J-M; Palacín, M R

2013-03-13

13

Synthesis and structural study of a new NASICON-type solid solution: Li 1-xLa x/3Zr 2(PO 4) 3  

Science.gov (United States)

A new complete solid solution of NASICON-type compounds between LiZr 2(PO 4) 3 and La 1/3Zr 2(PO 4) 3 was evidenced with the general formula Li 1-xLa x/3Zr 2(PO 4) 3 (0? x?1). These phases were synthesized by a complex polymerizable method and structurally characterized from Rietveld treatment of their X-ray and neutron powder diffraction data. This solid solution results from the substitution mechanism Li +?1/3La 3++2/3? leading to an increase of the vacancies number correlated to an increase of the La content. According to this substitution mechanism, the general formula can then be written Li 1-xLa x/3? 2x/3Zr 2(PO 4) 3 (0? x?1) in order to underline the correlation between the La content and the vacancies rate. For all the compounds, the structure is clearly related to that of the NASICON family with three crystallographic domains evidenced. For 0? x?0.5, all the members adopt at high temperature the typical NASICON-type structure (s.g. R3¯ c), while at lower temperature, their structure distorts to a triclinic form (s.g. C 1¯), as observed for LiZr 2(PO 4) 3 prepared above 1100 °C. Moreover, in this domain, the reversible transition is clearly soft and the transition temperature strongly depends of the x value. For 0.6? x?0.9, the compounds crystallize in a rhombohedral cell (s.g. R3¯), while for x=1, the phase La 1/3Zr 2(PO 4) 3 is obtained (s.g. P3¯, Z=6, a=8.7378(2) Å, c=23.2156(7) Å). This paper is devoted to the structure analysis of the series Li 1-xLa x/3Zr 2(PO 4) 3 (0? x?1), from X-ray and neutron powder thermo diffraction and transmission electron microscopy (TEM) studies.

Barré, M.; Crosnier-Lopez, M. P.; Le Berre, F.; Suard, E.; Fourquet, J. L.

2007-03-01

14

Synthesis and Vitrification of Nasicon Type Lithium Borophosphate Glasses  

Science.gov (United States)

NASICON type Li ion conducting Lithium borophosphate (Li3B2(PO4)3) and lead doped lithium borophosphate (Li3+xPbxB2-x(PO4)3 x = 0.2, 0.4, 0.6, 0.8) glass electrolyte has been prepared by melt quenching method. The effect of lead on the structure of the Lithium borophosphate glass network has been studied by Raman and 31P MAS Nuclear Magnetic resonance analysis. The behavior of the glass transition and electrical conductivity has been interpreted as a function of structural changes induced in the glass network when lead is doped in the Lithium borophosphate by means of DSC and ac impedance spectroscopic technique.

Nithya, H.; Kawamura, Junichi; Iwai, Yoshiki; Takekawa, Reiji; Kuwata, Naoaki; Matsuda, Yasutaka

2013-07-01

15

Synthesis of NASICON-type lithium zirconium phosphate  

International Nuclear Information System (INIS)

Methods of thermogravimetry and X-ray diffraction analysis are applied to study chemical transformations running in the process of synthesis of lithium-zirconium phosphate (LiZr2(PO4)3) with a NASICON structure. It is shown that on annealing of a 3Zr(HPO4)2·H2O+Li2CO3+ZrO2 composition mixture the formation of a NASICON phase begins already at 600 Deg C. However, further temperature increasing results in parallel formation of zirconium pyrophosphate and noncontrolled losses of lithium because of volatility of its compounds. A well formed high conductivity NASICON phase appears only above 1100 Deg C. It has been possible to obtain single-phase LiZr2(PO4)3 when using a two-step synthesis procedure only

16

31P MAS NMR Investigations of Crystalline and Glassy NASICON-Type Phosphates  

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31P MAS NMR investigations of crystalline and glassy NASICON-type phosphates have been carried out. The origin for the two signals in the case of the crystalline compounds is discussed. The spectra show the presence of pyrophosphate units in all glasses studied along with various other phosphate species resulting from structural disproportionation.

Sobha, K. C.; Rao, K. J.

1996-01-01

17

Synthesis of NASICON-type structured NaTi2(PO4)3-graphene nanocomposite as an anode for aqueous rechargeable Na-ion batteries  

Science.gov (United States)

A new solvothermal strategy combined with calcination has been developed to synthesize NaTi2(PO4)3-graphene nanocomposites. X-ray diffraction, thermogravimetric analysis, field-emission scanning electron microscopy and transmission electron microscopy were performed to characterize their microstructures and morphologies. It was found that NASICON-type structured NaTi2(PO4)3 nanoparticles with highly crystallinity were homogeneously anchored on the surface of conducting graphene nanosheets, forming a two-dimensional hybrid nanoarchitecture. A possible growth mechanism was also discussed based on time-dependent experiments. When used as anode materials for Na-ion batteries, the nanocomposites exhibited excellent electrochemical performance with high-rate capability and excellent cycling stability in 1 M Na2SO4 aqueous electrolyte. The electrode delivered high specific capacities of 110, 85, 65, 40 mA h g-1 at 2, 5, 10 and 20 C, respectively, and still retained 90% of the initial capacity after 100 cycles at 2 C.A new solvothermal strategy combined with calcination has been developed to synthesize NaTi2(PO4)3-graphene nanocomposites. X-ray diffraction, thermogravimetric analysis, field-emission scanning electron microscopy and transmission electron microscopy were performed to characterize their microstructures and morphologies. It was found that NASICON-type structured NaTi2(PO4)3 nanoparticles with highly crystallinity were homogeneously anchored on the surface of conducting graphene nanosheets, forming a two-dimensional hybrid nanoarchitecture. A possible growth mechanism was also discussed based on time-dependent experiments. When used as anode materials for Na-ion batteries, the nanocomposites exhibited excellent electrochemical performance with high-rate capability and excellent cycling stability in 1 M Na2SO4 aqueous electrolyte. The electrode delivered high specific capacities of 110, 85, 65, 40 mA h g-1 at 2, 5, 10 and 20 C, respectively, and still retained 90% of the initial capacity after 100 cycles at 2 C. Electronic supplementary information (ESI) available: Synthesis of graphite oxide, TG curve of NaTi2(PO4)3-GNS, XRD patterns and morphology of GO, TiO2-GNS, Ti5P4O20-GNS, and NaTi2(PO4)3-GNS. See DOI: 10.1039/c3nr06730k

Pang, Gang; Yuan, Changzhou; Nie, Ping; Ding, Bing; Zhu, Jiajia; Zhang, Xiaogang

2014-05-01

18

Photocatalytic activity of glass ceramics containing Nasicon-type crystals  

Energy Technology Data Exchange (ETDEWEB)

Graphical abstract: Display Omitted Highlights: ? Glass ceramics containing Nasicon-type crystals were prepared. ? The glass ceramics showed photocatalytic activity under UV irradiation. ? Higher activity was observed in the MgTi{sub 4}(PO{sub 4}){sub 6}- and CaTi{sub 4}(PO{sub 4}){sub 6}-containing glass ceramics. -- Abstract: Glass ceramics were prepared by heat-treating MO–TiO{sub 2}–P{sub 2}O{sub 5} (M = Mg, Ca, Sr and Ba) and R{sub 2}O–TiO{sub 2}–P{sub 2}O{sub 5}–SiO{sub 2} (R = Li, Na and K) glasses, and their photocatalytic activity was investigated. The crystalline phases precipitated in the glasses were only Nasicon-type crystals, MTi{sub 4}(PO{sub 4}){sub 6} or RTi{sub 2}(PO{sub 4}){sub 3}. Decomposition experiments of both methylene blue (MB) and acetaldehyde showed that the glass ceramics exhibited effective photocatalytic activity. The activity did not depend on the radius of the M{sup 2+} or R{sup +} ion, and higher activity was observed in the MgTi{sub 4}(PO{sub 4}){sub 6} and CaTi{sub 4}(PO{sub 4}){sub 6} precipitated glass ceramics.

Fu, Jie, E-mail: fu@ohara-inc.co.jp [R and D Department, Ohara Inc., Sagamihara-shi, Kanagawa 252-5286 (Japan)

2013-01-15

19

Photocatalytic activity of glass ceramics containing Nasicon-type crystals  

International Nuclear Information System (INIS)

Graphical abstract: Display Omitted Highlights: ? Glass ceramics containing Nasicon-type crystals were prepared. ? The glass ceramics showed photocatalytic activity under UV irradiation. ? Higher activity was observed in the MgTi4(PO4)6- and CaTi4(PO4)6-containing glass ceramics. -- Abstract: Glass ceramics were prepared by heat-treating MO–TiO2–P2O5 (M = Mg, Ca, Sr and Ba) and R2O–TiO2–P2O5–SiO2 (R = Li, Na and K) glasses, and their photocatalytic activity was investigated. The crystalline phases precipitated in the glasses were only Nasicon-type crystals, MTi4(PO4)6 or RTi2(PO4)3. Decomposition experiments of both methylene blue (MB) and acetaldehyde showed that the glass ceramics exhibited effective photocatalytic activity. The activity did not depend on the radius of the M2+ or R+ ion, and higher activity was observed in the MgTi4(PO4)6 and CaTi4(PO4)6 precipitated glass ceramics.

20

NASICON-type Na3V2(PO43  

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Full Text Available Single crystals of the title compound, trisodium divanadium(III tris(orthophosphate, were grown from a self-flux in the system Na4P2O7–NaVP2O7. Na3V2(PO43 belongs to the family of NASICON-related structures and is built up from isolated [VO6] octahedra (3. symmetry and [PO4] tetrahedra (.2 symmetry interlinked via corners to establish the framework anion [V2(PO43]3?. The two independent Na+ cations are partially occupied [site-occupancy factors = 0.805?(18 and 0.731?(7] and are located in channels with two different oxygen environments, viz sixfold coordination for the first (overline{3}. symmetry and eightfold for the second (.2 symmetry Na+ cation.

Igor V. Zatovsky

2010-02-01

 
 
 
 
21

Li 3- xTi 2(PO 4) 3 (0 ? x ? 1): A new mixed valent titanium(III/IV) phosphate with a NASICON-type structure  

Science.gov (United States)

A new NASICON-related structure of lithium titanium phosphate Li 2.72Ti 2(PO 4) 3 has been determined. This compound crystallizes in an orthorhombic system, Pbcn, with a = 12.064 (3) Å, b = 8.663 (3) Å, c = 8.711 (4) Å, V = 910.4 (8) Å 3, and Z = 4. The single crystal structure of this novel mixed valent titanium(III/IV) phosphate reveals one titanium atom per asymmetric unit. Two lithium sites are characterized by a pair of distorted polyhedra, Li(1)O 4 and Li(2)O 5, which share a common edge resulting in a short Li(1) … Li(2) distance, i.e., 2.29 (5) Å. Magnetic susceptibility and microprobe analysis confirmed the structural composition. The room temperature ionic conductivity is comparable with that of the known Li 1+ xTi IV2- xIn IIIx(PO 4) 3, which suggests possible fast ionic conductivity.

Wang, Shumin; Hwu, Shiou-Jyh

1991-02-01

22

The preparation, structure, and conductivity of scandium-substituted NASICONs  

Science.gov (United States)

A series of NASICON type compounds was prepared in which Sc(III) partially replaced Zr(IV). By simultaneously correlating the extent of this substitution with the amount of Si(IV) replacement of P(V) it was possible to obtain a series with a constant amount (3 mole) of sodium ion. All of the rhombohedral members of this series exhibited similar conductivities and activation energies over the temperature range 30-350°C. Transformation to the monoclinic phase occurred at a composition of Na 3Sc 0.5Zr 1.5Si 1.5P 1.5O 12 and was accompanied by a threefold increase in conductivity. Activation energies of the monoclinic (room temperature) phases in the temperature range 200-300°C were 0.2-0.23 eV. Crystal structures of the rhombohedral phase of composition Na 3ScZrSiP 2O 12 and the monoclinic phase, Na 3Sc 0.5Zr 1.5Si 1.5P 1.5O 12, were carried out by Rietveld refinement of their X-ray powder patterns. The structures confirmed those presented by Hong, and also confirmed the stoichiometry of these phases as evidenced from site occupancy refinement. These results were compared with the structure of a nonstoichiometric phase, Na 3.20Zr 1.68Si 1.84P 1.16O 11.54, prepared by a hydrothermal route. In the latter case it was shown that the low Zr content is due to Na + substitution for Zr 4+. No such substitution occurred in the scandium containing phases, and it is suggested that when Sc 3+ substitution for zirconium takes place it prevents the sodium ion from occupying these sites.

Subramanian, M. A.; Rudolf, P. R.; Clearfield, A.

1985-11-01

23

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

International Nuclear Information System (INIS)

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

24

Synthesis, Microstructure and Bulk Properties of Complex Nasicon-Type Ceramics  

Science.gov (United States)

Fast ion-conductors from the NASICON family (Na1+xZr2SixP3-xO12) have been the subject of extensive research due to their use in electrochemical devices such as batteries, fuel cells, thermoelectric generators and chemical sensors A fabrication challenge for these materials is to maintain long term chemical and physical stability in harsh environments We apply a multi-technique approach to show how partial substitutions with tetravalent and pentavalent cations produce NASICONs with specific morphology and modify the primary to secondary crystalline phase ratios. We use in situ synchrotron x-ray diffraction to investigate pressure-induced structural modifications and compressibility.

Lipinska, Kristina; Hemmers, Oliver; Romann, Julien; Sinogeikin, Stanislav; Kalita, Patricia; Balagopal, Shekar; Nickens, Anthony

2011-03-01

25

RbSn(2)(PO(4))(3), a NASICON-type phosphate.  

Science.gov (United States)

The title compound, rubidium ditin(IV) tris-(phosphate), RbSn(2)(PO(4))(3), belongs to the NASICON-type family of phosphates and crystallizes in the space group R[Formula: see text]. The structure is composed of PO(4) tetra-hedra (1 symmetry) and two slightly distorted SnO(6) octa-hedra, both with 3. symmetry, which are inter-linked through corner-sharing O atoms to form a (3) (?)[Sn(2)(PO(4))(3)](-) framework. The Rb(+) cations are located on threefold inversion axes in the voids of this framework and exhibit a coordination number of 12. The crystal studied was twinned by merohedry with a component ratio of 0.503:0.497. PMID:21754258

Zhao, Dan; Li, Feifei; Qiu, Shen; Jiao, Jiali; Ren, Junran

2011-05-01

26

RbSn2(PO4)3, a NASICON-type phosphate  

Science.gov (United States)

The title compound, rubidium ditin(IV) tris­(phosphate), RbSn2(PO4)3, belongs to the NASICON-type family of phosphates and crystallizes in the space group R . The structure is composed of PO4 tetra­hedra (1 symmetry) and two slightly distorted SnO6 octa­hedra, both with 3. symmetry, which are inter­linked through corner-sharing O atoms to form a 3 ?[Sn2(PO4)3]? framework. The Rb+ cations are located on threefold inversion axes in the voids of this framework and exhibit a coordination number of 12. The crystal studied was twinned by merohedry with a component ratio of 0.503:0.497. PMID:21754258

Zhao, Dan; Li, FeiFei; Qiu, Shen; Jiao, Jiali; Ren, Junran

2011-01-01

27

RbSn2(PO43, a NASICON-type phosphate  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, rubidium ditin(IV tris(phosphate, RbSn2(PO43, belongs to the NASICON-type family of phosphates and crystallizes in the space group Roverline{3}. The structure is composed of PO4 tetrahedra (1 symmetry and two slightly distorted SnO6 octahedra, both with 3. symmetry, which are interlinked through corner-sharing O atoms to form a 3?[Sn2(PO43]? framework. The Rb+ cations are located on threefold inversion axes in the voids of this framework and exhibit a coordination number of 12. The crystal studied was twinned by merohedry with a component ratio of 0.503:0.497.

Dan Zhao

2011-05-01

28

Reactions with ZrO(NO3)2 in the synthesis of solid electrolytes of the NASICON type  

International Nuclear Information System (INIS)

The process of NASICON solid phase synthesis is studied in detail. Solid phase reactions during the synthesis of solid electrolytes of the NASICON type taking place with zirconium dinitrate-oxide end at 300-400 deg C,i.e.before the teransition of appearing zirconium dioxide into the stable monoclinic modification The presense of the nitrate group brings about the decrease in the temperature of intensive decomposition of sodium carbonate and nitrate and sodium zirconate formation close to 180 deg C

29

Low-Temperature Triclinic Distortion in NASICON-Type LiSn 2(PO 4) 3  

Science.gov (United States)

The triclinic nature of the low-temperature modification of LiSn 2(PO 4) 3, heretofore considered as monoclinic, has been proved by detailed indexing of its X-ray diffraction powder pattern. The triclinic character of most low-temperature polymorphs of NASICON-type LiMe IV2(PO 4) 3is tentatively hypothesized, from this evidence and additional indications.

Iglesias, Juan E.; Sanz, Jesús; Martínez-Juárez, Ana; Rojo, José M.

1997-05-01

30

Synthesis and electric conductivity of solid electrolyte of NASICON type  

International Nuclear Information System (INIS)

The sequences of solid-phase reactions during synthesis of solid electrolyte corresponding to Na3Zr2Si2PO12 stoichiometric composition are studied. It is shown that solid-phase reaction of ZrO(NO3)2x2H2O, Na2CO3, NH4H2PO4 and amorphous SiO2 proceeds through stages of nitrate-zirconium oxide dehydration, ammonium dihydrophosphate decomposition, formation and decomposition of ammonium and sodium. Intermediate reaction products are sodium and zirconium phosphates, and some of ZrO2 takes part in the reaction in the form of amorphous or metastable tetragonal modification and another part transforms into a stable monoclinic one. NASICON formation starts at 1000 deg C, only at this stage silicon dioxide begins to react, which is already transformed from amorphous phase into a mixture of tridymite and ?-crystobalyte. After annealing at 1230 deg C a single-phase solid electrolyte Na3Zr2Si2PO12 having conductivity 0.14 S/cm at 300 deg C and 0.00028 S/cm at 25 deg C

31

Synthesis and structural study of a new NASICON-type solid solution: Li1- x La x /3Zr2(PO4)3  

International Nuclear Information System (INIS)

rsible transition is clearly soft and the transition temperature strongly depends of the x value. For 0.6?x?0.9, the compounds crystallize in a rhombohedral cell (s.g. R3-bar), while for x=1, the phase La1/3Zr2(PO4)3 is obtained (s.g. P3-bar, Z=6, a=8.7378(2) A, c=23.2156(7) A). This paper is devoted to the structure analysis of the series Li1- x La x /3Zr2(PO4)3 (0?x?1), from X-ray and neutron powder thermo diffraction and transmission electron microscopy (TEM) studies. - Graphical abstract: Schematic drawing of the space group evolution at 800 deg. C in the solid solution Li1- x La x /3Zr2(PO4)3 (0?x?1)

32

Structural and electrical properties of NASICON type solid electrolyte nanoscaled glass-ceramic powder by mechanical milling for thin film batteries.  

Science.gov (United States)

During last two decades, lithium-based glasses have been studied extensively as electrolytes for solid-state secondary batteries. For practical use, solid electrolyte must have high ionic conductivity as well as chemical, thermal and electrochemical stability. Recent progresses have focused on glass electrolytes due to advantages over crystalline solid. Glass electrolytes are generally classified into two types oxide glass and sulfide glass. Oxide glasses do not react with electrode materials and this chemical inertness is advantageous for cycle performances of battery. In this study, major effort has been focused on the improvement of the ion conductivity of nanosized LiAlTi(PO4)3 oxide electrolyte prepared by mechanical milling (MM) method. After heating at 1000 degrees C the material shows good crystallinity and ionic conductivity with low electronic conductivity. In LiTi2(PO4)3, Ti4+ ions are partially substituted by Al3+ ions by heat-treatment of Li20-Al2O3-TiO2-P2O5 glasses at 1000 degrees C for 10 h. The conductivity of this material is 1.09 x 10(-3) S/cm at room temp. The glass-ceramics show fast ion conduction and low E(a) value. It is suggested that high conductivity, easy fabrication and low cost make this glass-ceramics promising to be used as inorganic solid electrolyte for all-solid-state Li rechargeable batteries. PMID:23858924

Patil, Vaishali; Patil, Arun; Yoon, Seok-Jin; Choi, Ji-Won

2013-05-01

33

Na(4)FeFe(PO(4))(3), a new synthetic NASICON-type phosphate.  

Science.gov (United States)

This paper reports the crystal structure of tetra-sodium diiron tris(phosphate), Na(4)Fe(2+)Fe(3+)(PO(4))(3), which has been synthesized hydro-thermally at 773?K and 0.1?GPa. The crystal structure has been refined in the space group Rc and is identical to that of ?-NASICON. The heteropolyhedral framework is based on a regular alternation, in three dimensions, of corner-sharing PO(4) tetra-hedra and FeO(6) octa-hedra, constituting so-called 'lantern units' stacked along the c axis. The Na(+) cations are distributed over two crystallographic sites: the six-coordinated Na1 site which lies between two 'lantern units', and the eight-coordinated Na2 site which lies at the same z value as the P site. PMID:21582313

Hatert, Frédéric

2009-01-01

34

Na4Fe2+Fe3+(PO43, a new synthetic NASICON-type phosphate  

Directory of Open Access Journals (Sweden)

Full Text Available This paper reports the crystal structure of tetrasodium diiron tris(phosphate, Na4Fe2+Fe3+(PO43, which has been synthesized hydrothermally at 773?K and 0.1?GPa. The crystal structure has been refined in the space group Roverline{3}c and is identical to that of ?-NASICON. The heteropolyhedral framework is based on a regular alternation, in three dimensions, of corner-sharing PO4 tetrahedra and FeO6 octahedra, constituting so-called `lantern units' stacked along the c axis. The Na+ cations are distributed over two crystallographic sites: the six-coordinated Na1 site which lies between two `lantern units', and the eight-coordinated Na2 site which lies at the same z value as the P site.

Frédéric Hatert

2009-04-01

35

Local structure and lithium mobility in intercalated Li3Al(x)Ti(2-x)(PO4)3 NASICON type materials: a combined neutron diffraction and NMR study.  

Science.gov (United States)

The structural features of intercalated Li3AlxTi2-x(PO4)3 compounds, with x = 0 and 0.2, have been deduced by Rietveld analysis of neutron diffraction (ND) patterns recorded between 100 and 500 K. The Li insertion decreases the symmetry from R3?c to R3? in analyzed compounds. In pristine Li1+xAlxTi2-x(PO4)3 samples, Li occupies mainly six-fold M1 sites at ternary axes; but in lithiated Li3AlxTi2-x(PO4)3 samples, Li is located near M2 positions at M3/M3' four-fold coordinated sites. In both cases, Li arrangement minimizes electrostatic Li-Li repulsions. The insertion of lithium resulted in the reduction of Ti(4+) to Ti(3+) that shifts (7)Li, (27)Al and (31)P MAS-NMR resonances towards more positive chemical shifts, improving the resolution of different sites. The detection of twelve components in (7)Li MAS-NMR spectra recorded at room temperature suggests the location of Li(+) ions at three-oxygen faces that define M2 cavities. From (7)Li MAS-NMR spectra, the occupancy of sites and mobility of lithium were investigated in the temperature range 100-500 K. The correlation between structural information, deduced by neutron diffraction, and lithium mobility, deduced by NMR spectroscopy, provides new insights into structural factors that affect lithium mobility in materials with NASICON structure. PMID:25070935

Arbi, K; Hoelzel, M; Kuhn, A; García-Alvarado, F; Sanz, J

2014-09-14

36

NASICON-type Na3V2(PO4)3  

Science.gov (United States)

Single crystals of the title compound, tris­odium divanadium(III) tris­(orthophosphate), were grown from a self-flux in the system Na4P2O7–NaVP2O7. Na3V2(PO4)3 belongs to the family of NASICON-related structures and is built up from isolated [VO6] octa­hedra (3. symmetry) and [PO4] tetra­hedra (.2 symmetry) inter­linked via corners to establish the framework anion [V2(PO4)3]3?. The two independent Na+ cations are partially occupied [site-occupancy factors = 0.805?(18) and 0.731?(7)] and are located in channels with two different oxygen environments, viz sixfold coordination for the first (. symmetry) and eightfold for the second (.2 symmetry) Na+ cation. PMID:21579586

Zatovsky, Igor V.

2010-01-01

37

NASICON-type Na(3)V(2)(PO(4))(3).  

Science.gov (United States)

Single crystals of the title compound, tris-odium divanadium(III) tris-(orthophosphate), were grown from a self-flux in the system Na(4)P(2)O(7)-NaVP(2)O(7). Na(3)V(2)(PO(4))(3) belongs to the family of NASICON-related structures and is built up from isolated [VO(6)] octa-hedra (3. symmetry) and [PO(4)] tetra-hedra (.2 symmetry) inter-linked via corners to establish the framework anion [V(2)(PO(4))(3)](3-). The two independent Na(+) cations are partially occupied [site-occupancy factors = 0.805?(18) and 0.731?(7)] and are located in channels with two different oxygen environments, viz sixfold coordination for the first (. symmetry) and eightfold for the second (.2 symmetry) Na(+) cation. PMID:21579586

Zatovsky, Igor V

2010-01-01

38

Synthesis and characterization of the variable-composition phase Na1-xNi1-xCr1+x(MoO4)3 (0?x?0.4) with NASICON structure  

International Nuclear Information System (INIS)

Conditions of synthesis of phase of variable composition Na1-xNi1-xCr1+x(MoO4)3 (0?x?0.4) crystallizing in nasicon structural type are studied. Using the data of roentgenographic analysis crystal lattice parameters are calculated, IR and Raman spectra of phase of variable composition are characterized

39

Relation structure-fast ion conduction in the NASICON solid solution  

Science.gov (United States)

Crystal determinations of the rhombohedral phase (space group R overline3c ), for different compositions (2 NASICON solid solution Na 1+ xZr 2Si xP 3- xO 12, have been performed at different temperatures by X-ray diffraction. We observe, as a consequence of interionic repulsions, the partial occupation of a mid-Na interstitial site within the conduction path. The composition dependence of the mid-Na occupation factor, maximum at x = 2, explains the maximum of the c hexagonal parameter and of the Na(1)-oxygen average distance observed at about x = 2. Moreover, structural results clearly suggest that the enhanced conductivity at x = 2 arises from sodium interactions instead of geometry changes of the framework.

Boilot, J. P.; Collin, G.; Colomban, Ph.

1988-03-01

40

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.

 
 
 
 
41

?-Na3M2(PO4)3 (M = Ti, Fe): absolute cationic ordering in NASICON-type phases.  

Science.gov (United States)

The structure of the fully ordered ?-Na(3)Ti(2)(PO(4))(3) NASICON compound was elucidated using high-quality single-crystal data. The cation/vacancy distribution forms a homogeneous 3D arrangement and could represent the absolute cationic ordering available in the full Na(3)M(2)(PO(4))(3) series, as verified for M = Fe. For M = Ti, the reversible ? ? ? transition was observed at 85 °C, leading to the standard disordered R ?3c ? model. Through JPDF analysis, the most probable Na(+) zigzag M(2)-M(1) diffusion scheme was directly deduced using our accurate crystallographic data. PMID:21721564

Kabbour, Houria; Coillot, Daniel; Colmont, Marie; Masquelier, Christian; Mentré, Olivier

2011-08-10

42

New Titanium-Vanadium Phosphates of Nasicon and Langbeinite Structures, and Differences between the Two Structures toward Deintercalation of Alkali Metal  

Science.gov (United States)

Mixed metal phosphates of the general formula Ax TiV III(PO 4) 3, where A = Na, K, or Ba and (0 NASICON structure, the potassium compound, K 2TiV(PO 4) 3, crystallizes with the langbeinite structure. BaTiV(PO 4) 3 is dimorphic, adopting the NASICON structure at lower temperatures and the langbeinite structure at higher temperatures. Ba 1.5V 2(PO 4) 3 and BaKV 2(PO 4) 3, on the other hand, crystallize only with the langbeinite structure. Oxidative deintercalation of sodium from Na 3TiV(PO 4) 3 readily occurs, yielding Na xTiV(PO 4) 3 ( x ˜ 1.0) and retaining the NASICON framework, while a similar deintercalation of potassium does not occur from the langbeinite K 2TiV(PO 4) 3, revealing a difference in reactivity between the two structures: NASICON, being a skeleton structure with an interconnected interstitial space, facilitates mobility of alkali metal ions through the crystal, while langbeinite, being a true cage structure, does not permit a similar mobility.

Rangan, K. Kasthuri; Gopalakrishnan, J.

1994-03-01

43

Relation between structure and conductivity in the nasicon solid solution system  

Science.gov (United States)

The changes in crystal structure which accompany the marked increase in conductivity with change of composition in the NASICON system Na(1+x)Zr2Si(x) P(x-x) were established by Rietveld analysis of neutron powder diffraction data. Structural parameters were refined for samples extending across the system: x = 1.0, 2.5 and 3.0 (hexagonal, R3 bar c) and x = 1.6 and 2.0 (mono-clinic, C2/c). The Na(1) site occupied in x = 0 remains fully occupied; Na(2) fills progressively with increasing x. In the monoclinic phases. Na(2) splits to two symmetry-independent positions which are not equally occupied. Extrapolation indicates that these sites have equal occupancy (i.e., equal energy) at x = 2.1, a composition close to that of maximum conductivity. The principal change in the framework with change is composition is distortion and increased rotation of the orientation of the Si/P tetrahedron up to x = 2, followed by progressive return towards the original orientation for larger x. The rotation stretches the length of the Na(1) octahedron along c and accounts for an anomalous maximum in the variation of c with composition.

Wuensch, B. J.; Schioler, L. J.; Prince, E.

1983-10-01

44

Na4Fe2+Fe3+(PO4)3, a new synthetic NASICON-type phosphate  

Science.gov (United States)

This paper reports the crystal structure of tetra­sodium diiron tris(phosphate), Na4Fe2+Fe3+(PO4)3, which has been synthesized hydro­thermally at 773?K and 0.1?GPa. The crystal structure has been refined in the space group R c and is identical to that of ?-NASICON. The heteropolyhedral framework is based on a regular alternation, in three dimensions, of corner-sharing PO4 tetra­hedra and FeO6 octa­hedra, constituting so-called ‘lantern units’ stacked along the c axis. The Na+ cations are distributed over two crystallographic sites: the six-coordinated Na1 site which lies between two ‘lantern units’, and the eight-coordinated Na2 site which lies at the same z value as the P site. PMID:21582313

Hatert, Frederic

2009-01-01

45

Synthesis of sodium zirconate-phosphate and zirconate-silicate forming solid solutions of the NASICON type  

International Nuclear Information System (INIS)

Synthesis of NASICON-type solid electrolytes through heating of Na2CO3, ZrO(NO3)2·2H2O and NH4H2PO4(or SiO2) ternary mixtures occurs through the stage of formation and decomposition of sodium nitrate. Formation of NaZr2P3O12 begins at 250 deg C and completes at 1000 deg C within the phosphatic system at stoichiometric proportion of the initial reagents. At the excess of sodium carbonate ZrO2 and Na2PO4 mixture is the reaction final product. Na2ZrSi3O10 is the reaction product within the silicate system at different proportions of initial components and at 1200 deg C temperature

46

31P and 29Si NMR investigations of the structure of NASICON-compounds  

International Nuclear Information System (INIS)

First systematic NMR investigations of several NASICON compounds are described. In the original NASICON Na1+xZr2(SiO4)x(PO4)3-x the observed down-field shift (for increasing x) of both 31P and 29Si MAS NMR lines is explained by a change of the net atomic charge of the zirconium atoms caused by the substitution of the lattice positions of phosphorus by silicon atoms. The 'von Alpen' compound Na4ZrSi3O10 consists of two phases; the crystalline Na4Zr2(SiO4)3 and the glassy phase 2 Na2O · 3 SiO2. Moreover, it is shown that NMR can be used to investigate the statistical substitution of lattice positions of the zirconium atoms by magnesium atoms in the mixed crystals Na1+2xMgxZr2-x(PO4)3. (author)

47

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

48

Double NASICON-type cell: ordered Nd3+ distribution in Li0.2Nd0.8/3Zr2(PO4)3.  

Science.gov (United States)

The NASICON compound Li(0.2)Nd(0.8/3)Zr(2)(PO(4))(3), synthesized by a sol-gel process, has been structurally characterized by TEM and powder diffraction (neutron and X-ray). It crystallizes in the space group R3[combining macron] (No. 148): at room temperature, the Nd(3+) ions present an ordered distribution in the [Zr(2)(PO(4))(3)](-) network which leads to a doubling of the classical c parameter (a = 8.7160(3) A, c = 46.105(1) A). Above 600 degrees C, Nd(3+) diffusion occurs leading at 1000 degrees C to the loss of the supercell. This reversible cationic diffusion in a preserved 3D [Zr(2)(PO(4))(3)](-) network is followed through thermal X-ray diffraction. Ionic conductivity measurements have been undertaken by impedance spectroscopy, while some results concerning the sintering of the NASICON compound are given. PMID:18521448

Barré, Maud; Crosnier-Lopez, Marie-Pierre; Le Berre, Françoise; Bohnké, Odile; Suard, Emmanuelle; Fourquet, Jean-Louis

2008-06-21

49

New NASICON-type Li{sub 2}Ni{sub 2}(MoO{sub 4}){sub 3} as a positive electrode material for rechargeable lithium batteries  

Energy Technology Data Exchange (ETDEWEB)

A new lithiated NASICON-type polyanion material, Li{sub 2}Ni{sub 2}(MoO{sub 4}){sub 3} was synthesized for the first time by means of a low temperature approach involving glycine as a mild combustion agent. The synthesized product, Li{sub 2}Ni{sub 2}(MoO{sub 4}){sub 3}, was found to crystallize in an orthorhombic structure (space group Pmcn) with cell parameters a=10.424(4) A, b=17.525(1) A and c=5.074(3) A. The electronic state of each element present in the new material was confirmed by X-ray photoelectron spectroscopic (XPS) analysis. The metals content present in the new material was analyzed using inductively coupled plasma emission spectroscopy (ICP-AES). Fiber-like submicrometre grains were evident from scanning electron microscopy (SEM) analysis of the annealed powders. The electrochemical performance of the new material was examined in a half-cell configuration against lithium metal employing a conventional Li{sup +} non-aqueous electrolyte. Slow scan cyclic voltammetry (SSCV) revealed the electrochemical reversibility of the material between the potential window of 4.9 V (charge cutoff) and 1.5 V (discharge cutoff). Reversible extraction/insertion of Li{sup +} from and into the framework structure delivered a reversible capacity of =115 mA h/g (4.9-1.5-V window) after the first charge/discharge cycle.

Prabaharan, S.R.S.; Michael, M.S. [Lithium Battery Technology Group, Faculty of Engineering, Center for Smart Systems and Innovation, Multimedia University, Jalan Multimedia, 63100 Cyberjaya (Malaysia); Fauzi, A. [School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Pulau Pinang (Malaysia); Begam, K.M. [Electrical, Automation and Computer Section, Universiti Kuala Lumpur-Malaysia France Institute, 43650 Bandar Baru Bangi (Malaysia)

2004-07-30

50

A study on lithium/air secondary batteries - Stability of NASICON-type glass ceramics in acid solutions  

Energy Technology Data Exchange (ETDEWEB)

The stability of a NASICON-type lithium ion conducting solid electrolyte, Li{sub 1+x+y}Ti{sub 2-x}Al{sub x}P{sub 3-y}Si{sub y}O{sub 12} (LTAP), in acetic acid and formic acid solutions was examined. XRD patterns of the LTAP powders immersed in 100% acetic acid and formic acid at 50 C for 4 months showed no change as compared to the pristine LTAP. However, the electrical conductivity of LTAP drastically decreased. On the other hand, no significant electrical conductivity change of LTAP immersed in lithium formate saturated formic acid-water solution was observed, and the electrical conductivity of LTAP immersed in lithium acetate saturated acetic acid-water increased. Cyclic voltammogram tests suggested that acetic acid was stable up to a high potential, but formic acid decomposed under the decomposition potential of water. The acetic acid solution was considered to be a candidate for the active material in the air electrode of lithium-air rechargeable batteries. The cell reaction was considered as 2Li + 2 CH{sub 3}COOH + 1/2O{sub 2} = 2CH{sub 3}COOLi + H{sub 2}O. The energy density of this lithium-air system is calculated to be 1477 Wh kg{sup -1} from the weights of Li and CH{sub 3}COOH, and an observed open-circuit voltage of 3.69 V. (author)

Shimonishi, Y.; Zhang, T.; Imanishi, N.; Hirano, A.; Takeda, Y.; Yamamoto, O. [Department of Chemistry, Faculty of Engineering, Mie University, 1577 Kurimamachiay-cho, Tsu, Mie 514-8507 (Japan); Johnson, P.; Sammes, N. [Department of Metallurgical and Materials Engineering, Colorado School of Mines, 1500 Illinois Street, Golden, CO 80401 (United States)

2010-09-15

51

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)

52

Li 2NaV 2(PO 4) 3: A 3.7 V Lithium-Insertion Cathode with the Rhombohedral NASICON Structure  

Science.gov (United States)

Li 2NaV 2(PO 4) 3 has been prepared in the rhombohedral NASICON structure via ion exchange from Na 3V 2(PO 4) 3. As a lithium-insertion cathode material, Li 2NaV 2(PO 4) 3 exhibits a specific discharge capacity of 96 mAh g -1 at a current density of 0.50 mA cm -2 with a clear plateau near 3.7 V versus lithium metal. Approximately 10% of the capacity is lost through the first 50 cycles, after which the capacity appears to stabilize. During charge and discharge, the Na + ions tend to remain immobilized in the A(1) site of the NASICON structure, suggesting a direct A(2)? A(2) lithium-transport mechanism.

Cushing, Brian L.; Goodenough, John B.

2001-12-01

53

Phase transition in stoichiometric NASICON  

International Nuclear Information System (INIS)

The authors discuss the microscopic mechanism of the phase transition B2/b ? R3c in stoichiometric NASICON with the aid of published data on the structures of the two modifications of this compound. The low-temperature phase is treated as dipole-ordered; the dipole order is created by compensated statistical Na dipoles. It is shown that the splitting of the cation positions improves the balance of valence forces

54

Crystal structure of the true Nasicon: Na/sub 3/Zr/sub 2/Si/sub 2/PO/sub 12/  

International Nuclear Information System (INIS)

For the first time, the results of single crystal determination of the true Nasicon are given. The structure refinement yielded the following composition: Na/sub 3.09(8)/Zr/sub 2.01(1)/P/sub 0.91/Si/sub 2.09/O/sub 12/. Evidence of the total occupancy of the Zr octahedron is found, displaying that only the Si/P non-stoichiometry mechanism is present in the Nasicon crystal. For the two temperatures which have been investigated (R.T. and 623K), the structures are very close to that of the Nasicon analog: Na/sub 3/Sc/sub 2/P/sub 3/O/sub 12/. However the Si/P substitution prevents the sodium long range ordering even in the monoclinic low temperature phase and therefore the cross over to the rhombohedral symmetry only involves very small atomic displacements. For both structures, a new sodium position (mid-Na) is displayed in the conduction channel, intermediate between the usual Na(1) and Na(2) sites

55

Electrochemical properties of rechargeable aqueous lithium ion batteries with an olivine-type cathode and a Nasicon-type anode  

Energy Technology Data Exchange (ETDEWEB)

Rechargeable aqueous lithium ion batteries have been developed by using olivine LiMn{sub 0.05}Ni{sub 0.05}Fe{sub 0.9}PO{sub 4} as cathode material, Nasicon LiTi{sub 2}(PO{sub 4}){sub 3} as anode material, and saturated Li{sub 2}SO{sub 4} solution as electrolyte. The cycling performance and rate capability of these batteries have been investigated. At a current density of 0.2 mA/cm{sup 2}, the initial discharge capacity of the battery was approximately 103.9 mAh/g, and the potential plateau was located at 0.92 V. The rate capability of aqueous electrolyte was found to be preferable to that of organic electrolyte. Such inexpensive, secure and high rate rechargeable lithium ion battery should have a potential for use in many applications. (author)

Liu, Xiao-Hong; Saito, Taishi; Doi, Takayuki; Okada, Shigeto; Yamaki, Jun-ichi [Institute of Material Chemistry and Engineering Science, Kyushu University, Kasuga Koen 6-1, Kasuga 816-8580 (Japan)

2009-04-01

56

Neutron Rietveld analysis of structural changes in NASICON solid solutions Nasub(1+x)Zr2Sisub(x)Psub(3-x)O12 at elevated temperatures: x = 1.6 and 2.0 at 3200C  

International Nuclear Information System (INIS)

Neutron Rietveld analyses of the structures of NASICON solid solutions as a function of composition have been extended to 3200C for the high-conductivity compositions x = 1.6 and 2.0. The transformation from the room temperature monoclinic C2/c structure to the hexagonal R3-barc high temperature phase involves small atomic displacements, ranging from 0.385A for Na(2) down to shifts of only a few hundredths of an Angstrom for several framework ions. The Na(1) interstice remains fully occupied to the temperature presently examined. No evidence for partial occupancy of the Zr octahedron is found, a non-stoichiometry which is possible but not obligatory for NASICON. The distortions of the framework are largest at x = 2.0 as at room temperature. The radius of the windows between Na sites at 3200C remain largest at the composition with x = 2.0 for both a Na(1)-Na(2) jump and a Na(2)-Na(2) jump. The radii are significantly larger than the maximum value available among the three symmetry-independent paths in the room-temperature monoclinic structures for both types of diffusion paths. (orig.)

57

Lithium mobility in the NASICON-type compound LiTi2(PO4)3 by nuclear magnetic resonance and impedance spectroscopies  

International Nuclear Information System (INIS)

Lithium mobility in LiTi2(PO4)3 has been followed by 7Li NMR and impedance spectroscopies. From this analysis, three stages have been distinguished. (1) Below 230 K, lithium occupies preferentially the octahedral M1 sites of the NASICON structure. (2) Between 230 and 330 K, a low correlated and thermally activated lithium motion, with Ea = 0.47 eV, is operating, as deduced from both techniques. (3) Above 330 K, the activation energy decreases and a more extended lithium ionic motion is established. As the lithium mobility increases, progressive occupation of the eight-coordinated M2 sites is deduced from NMR data. (author)

58

A study into the extracted ion number for NASICON structured Na?V?(PO?)? in sodium-ion batteries.  

Science.gov (United States)

Excellent C-rate and cycling performance with a high specific capacity of 117.6 mA h g(-1) have been achieved on NASICON-structure Na3V2(PO4)3 sodium-ion batteries. Two different Na sites, namely Na(1) and Na(2), are reported in the open three-dimensional framework, of which the ions at the Na(2) sites should be mainly responsible for the electrochemical properties. It is vitally important and interesting to find that there are two kinds of possible ion occupation of Na ions in Na3V2(PO4)3 and the investigation of ion-extraction number is firstly explored by discussing ion occupations with the help of first-principles calculations. The ion occupation of 0.75 for all Na sites is suitable for the configuration of [Na3V2(PO4)3]2, and the two-step extraction process accompanied by structure reorganization can account for the theoretical capacity of Na3V2(PO4)3. PMID:25028981

Song, Weixin; Cao, Xiaoyu; Wu, Zhengping; Chen, Jun; Huangfu, Kaili; Wang, Xiaowen; Huang, Yaliang; Ji, Xiaobo

2014-09-01

59

Superior charge-transfer kinetics of NASICON-type Li3V2(PO4)3 cathodes by multivalent Al3+ and Cl? substitutions  

International Nuclear Information System (INIS)

Graphical abstract: Superior kinetic properties are noted for the multivalent Al3+ and Cl? substituted NASICON type Li3V2(PO4)3 cathodes, which enables extraordinary cycling performance especially at high current rates. -- Abstract: The kinetic properties of Li insertion in NASICON-type Li3V2(PO4)3 cathodes were enhanced substantially by Al3+ and Cl? multivalent substitutions of various concentrations. Pristine and carbon coated, Al-doped Li3V2(PO4)3 were also prepared by a conventional solid-state approach under optimized conditions. Samples phase purity was investigated through X-ray diffractometry. Li insertion was studied in half-cells at 3-4.8 V vs. Li for the removal of 3 mol of Li. Carbon-coated Li3V1.98Al0.02(PO4)2.99Cl0.01 showed the highest reversible insertion of 2.71 mol of Li (178 mAh g?1) at a current density of 0.2 mA cm?2. It showed a capacity retention of over 80% after 100 cycles. Cl? substitution led to improved performance under harsh conditions of 15 C rate and high temperature (50 °C). The enhancement of Li ion kinetics was demonstrated through cyclic voltammetry in a two-electrode configuration and electrochemical impedance spectrosco

60

Synthesis of Li1+xMIIIxTi2-x(PO4)3 with nasicon structure, using sol-gel methods. Study of the relationship microstructure electrical properties  

International Nuclear Information System (INIS)

Compounds of formula Li1+xMIIIxTi2-x(PO4)3 with MIII = 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, LiTi2(PO4)3 until values of 9x10-4 S cm-1 at room temperature in the chromium-doped material. (Author)

 
 
 
 
61

Hydrothermal synthesis, structural and physico-chemical characterizations of two Nasicon phosphates: M{sub 0.50}{sup II}Ti{sub 2}(PO{sub 4}){sub 3} (M = Mn, Co)  

Energy Technology Data Exchange (ETDEWEB)

The family of titanium Nasicon-phosphates of generic formula M{sub 0.5}{sup II}Ti{sub 2}(PO{sub 4}){sub 3} has been revisited using hydrothermal techniques. Two phases have been synthesized: Mn{sub 0.5}{sup II}Ti{sub 2}(PO{sub 4}){sub 3} (MnTiP) and Co{sub 0.5}{sup II}Ti{sub 2}(PO{sub 4}){sub 3} (CoTiP). Single crystal diffraction studies show that they exhibit two different structural types. Mn{sub 0.5}{sup II}Ti{sub 2}(PO{sub 4}){sub 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) A{sup 3} and Z = 6). The Co{sub 0.5}{sup II}Ti{sub 2}(PO{sub 4}){sub 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) A{sup 3} and Z = 6). These two compounds are clearly related to the parent Nasicon-type rhombohedral structure, which can be described using [Ti{sub 2}(PO{sub 4}){sub 3}] framework composed of two [TiO{sub 6}] octahedral interlinked via three [PO{sub 4}] tetrahedra. {sup 31}P 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.

Essehli, Rachid, E-mail: essehli_rachid@yahoo.fr [Laboratory of Mineral Solid and Analytical Chemistry ' LMSAC' , 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 ' LMSAC' , Department of Chemistry, Faculty of Sciences, University Mohamed I, Po. Box 717, 60000 Oujda (Morocco); Benmokhtar, S. [Laboratoire de Chimie des Materiaux Solides (LCMS) Universite HassanII-Mohammedia, Faculte des Sciences Ben M' Sik, Departement de Chimie, Casablanca (Morocco); Fejfarova, Karla; Dusek, Michal [Institute of Physics, Na Slovance 2, 182 21 Praha 8 (Czech Republic)

2009-07-01

62

High Microwave Susceptibility of NaH 2PO 4·2H 2O: Rapid Synthesis of Crystalline and Glassy Phosphates with NASICON-Type Chemistry  

Science.gov (United States)

High microwave susceptibility of NaH 2PO 4·2H 2O has been discovered. This hydrated acid phosphate of sodium can be heated upto 1000 K or more when exposed to 2.45 GHz microwaves. Using this, a novel microwave-assisted preparation of a number of important crystalline and glassy materials with NASICON-type chemistry has been accomplished in less than 8 min which is only a fraction of the time required for conventional synthetic procedures. The present single-shot approach to the preparation of phosphates is attractive in terms of its simplicity, rapidity, and general applicability. A "step-ladder" heating mechanism has been proposed to account for the high microwave absorbing ability of NaH 2PO 4·2H 2O.

Vaidhyanathan, B.; Rao, K. J.

1997-09-01

63

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)

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.

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

64

Li-ion transport in all-solid-state lithium batteries with LiCoO{sub 2} using NASICON-type glass ceramic electrolytes  

Energy Technology Data Exchange (ETDEWEB)

LiCoO{sub 2} thin films were deposited on the NASICON-type glass ceramics, Li{sub 1+x+y}Al{sub x}Ti{sub 2-x}Si{sub y}P{sub 3-y}O{sub 12}, by radio frequency (RF) magnetron sputtering and were annealed at different temperatures. The as-deposited and the annealed LiCoO{sub 2} thin films were characterized by X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscopy (SEM). It was found that the films exhibited a (1 0 4) preferred orientation after annealing and Co{sub 3}O{sub 4} was observed by annealing over 500 C due to the reaction between the LiCoO{sub 2} and the glass ceramics. The effect of annealing temperature on the interfacial resistance of glass ceramics/LiCoO{sub 2} and Li-ion transport in the bulk LiCoO{sub 2} thin film was investigated by galvanostatic cycling, cyclic voltammetry (CV), potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS) with the Li/PEO/glass ceramics/LiCoO{sub 2} cell. The cell performance was limited by the Li-ion diffusion resistance in Ohara/LiCoO{sub 2} interface as well as in bulk LiCoO{sub 2}. (author)

Xie, J.; Imanishi, N.; Zhang, T.; Hirano, A.; Takeda, Y.; Yamamoto, O. [Department of Chemistry, Faculty of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507 (Japan)

2009-04-01

65

Characterization of soft-combustion-derived NASICON-type Li{sub 2}Co{sub 2}(MoO{sub 4}){sub 3} for lithium batteries  

Energy Technology Data Exchange (ETDEWEB)

This work describes the synthesis of a new polyanion material, Li{sub 2}Co{sub 2}(MoO{sub 4}){sub 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. Li{sub 2}Co{sub 2}(MoO{sub 4}){sub 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 {mu}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{sup +} extraction/insertion in lithium-containing test cells.

Prabaharan, S.R.S.; Ramesh, S.; Michael, M.S.; Begam, K.M

2004-10-15

66

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

67

NASICON-related Na?.?Mn?.?Fe?.?(PO?)?.  

Science.gov (United States)

The solid solution, sodium [iron(III)/manganese(II)] tris-(orthophosphate), Na?.?Mn?.?Fe?.?(PO?)?, was obtained using a flux method. Its crystal structure is related to that of NASICON-type compounds. The [(Mn/Fe)?(PO?)?] framework is built up from an (Mn/Fe)O?octa-hedron (site symmetry 3.), with a mixed Mn/Fe occupancy, and a PO? tetra-hedron (site symmetry .2). The Na? cations are distributed over two partially occupied sites in the cavities of the framework. One Na? cation (site symmetry -3.) is surrounded by six O atoms, whereas the other Na? cation (site symmetry .2) is surrounded by eight O atoms. PMID:22807697

Yatskin, Michael M; Strutynska, Nataliya Yu; Baumer, Vyacheslav N; Ogorodnyk, Ivan V; Slobodyanik, Nikolay S

2012-07-01

68

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 amountsamounts

69

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)

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)

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

2010-07-01

70

Synthesis and crystal structure of NZP-type thorium-zirconium phosphate.  

Science.gov (United States)

Microcrystals of Th(1/4)Zr(2)(PO(4))(3) were synthesized by thermal treatment (900 degrees C) of the material obtained using sol-gel technology (including organic complex formation and etherification). Their structure [hexagonal, P3c, a = b = 8.7311(4) A, c = 23.309(2) A] includes the three-dimensional [Zr(2)(PO(4))(3)](-) NASICON-type network and extraframework 6-fold-coordinated thorium(IV) cations. PMID:19739666

Orlova, Albina I; Volgutov, Valeriy Yu; Castro, Germán R; García-Granda, Santiago; Khainakov, Sergei A; García, José R

2009-10-01

71

Equilibrium relations in the system TiO2/V2O5/P2O5 and crystal structure of a NASICON-related vanadyl(V) titanium(IV) phosphate  

International Nuclear Information System (INIS)

Vanadyl(V)–titanium–orthophosphate (VVO)TiIV6(PO4)9 is formed by solid state reactions in the temperature range 525???780 °C. At higher temperature decomposition into V2O5 and the hitherto unknown solid solution Ti(P1?xVx)2O7 (0?x?0.23; 0.30?x?0.43) is observed. The process of phase formation has been monitored by MAS-NMR (31P, 51V) spectroscopy. Equilibrium phase relations in the quaternary system TiO2/VO2.5/PO2.5 have been determined. A structure analysis from X-ray single-crystal data (P63/m (No. 176), Z=2; a=8.4438(3) Å, c=22.215(1) Å, 14 independent atoms, 87 variables, 2066 unique reflections, R1=0.032, wR2=0.084) shows the relationship of (VVO)TiIV6(PO4)9 to the NASICON structure family. In marked contrast to the other members of this family [TiIV2O9] double-octahedra and strongly distorted tetrahedral [(VV=O)O3] groups are observed besides isolated [TiIVO6] octahedra and phosphate tetrahedra. The structure model is in agreement with the results from MAS-NMR (31P, 51V) spectroscopy. - Graphical abstract: (VVO)TiIV6(PO4)9 belongs to the NASICON structure family. Its structure contains [TiIV2O9] double-octahedra and unprecedented, strongly distorted tetrahedral [(VV=O)O3] groups, in stark contrast to other members of this family. The structure model is in agreement with the results from MAS-NMR (31P, 51V) spectroscopy. Highlights: ? Equilibrium relations for the subsolidus have been established for the system TiO2/V2O5/P2O5. ? Phase formation has been monitored by XRPD as well as by 31P- and 51-MAS-NMR. ? A solid solution Ti(P1?xVx)2O7 exists up to x=0.43 with a miscibility gap at 0.23?x?0.30. ? The crystal structure of the new NASICON-related phosphate (VVO)TiIV6(PO4)9 is reported. ? The crystal structure contains the unprecedented [(V=O)O3] group.

72

Dielectric spectroscopy studies of NASICON materials  

Science.gov (United States)

All samples of NASICON have been synthesized by taking new chemical (Na2.H.PO4.2H2O) by solid sate reaction method at different sintering temperature range (1150-1250 °C). The synthesized samples were characterized by X-ray powder diffraction and Impedance spectroscopy. The variation of (?') with frequency indicates the relaxation in all the samples. A high degree of dispersion with temperature at low frequency was observed which indicates that hopping type conduction mechanism is occurring in all samples. As the frequency and temperature increased the imaginary part of impedance decreased indicating that with increase in temperature and frequency the conduction is increasing. The sample sintered at 1200 °C showed best result than other sintered samples at 1150 °C and 1250 °C respectively.

Jha, Paramjyot Kumar; Pandey, O. P.; Singh, K.

2013-06-01

73

Non-polarisable dry electrode based on NASICON ceramic.  

Science.gov (United States)

A NASICON-type ceramic (high sodium ion conductor) is proposed to record bioelectric signals. The electrode does not need gel before its application. The principle of the measurements is based on a sodium ion exchange between the skin and the material. Electrical measurements performed in saline solutions show that the electrode is slightly polarisable. The skin-electrode impedance was investigated. The impedance decreases as a function of the time of application. The resistive component is the major source of the impedance change. This can be explained by the perspiration process which occurs immediately with time after the application of the NASICON-based electrode on the skin. The skin condition is also an important parameter. NaCl saline solution or abrasion causes the resistance to decrease markedly. PMID:7666693

Gondran, C; Siebert, E; Fabry, P; Novakov, E; Gumery, P Y

1995-05-01

74

Phase transitions and ionic mobility in hydrogen zirconium phosphates with the NASICON structure, H1±XZr2-XMX(PO4)3.H2O, M = Nb, Y  

International Nuclear Information System (INIS)

Phase transitions and the mobility of proton-containing groups in hydrogen zirconium phosphate HZr2(PO4)3.nH2O with the NASICON structure were studied by X-ray powder diffraction, 1H, 31P NMR, IR spectroscopy and TG analysis. Heating HZr2(PO4)3.H2O above 420 K results in dehydration and in a rhombohedral-triclinic phase transition. Continued heating to about 490 K results in the thermal activation of cation disordering and phase transition of HZr2(PO4)3 from triclinic to rhombohedral phase. Parameter 'a' of HZr2(PO4)3 lattice decreases during the heating. It is shown that oxonium ions in HZr2(PO4)3.H2O are characterized by high rotation and translation mobility. Rotation mobility of oxonium ions can be increased by the substitution of zirconium by yttrium or niobium

75

Investigation of the gas sensitive properties of SnO2/NASICON-Composits  

Digital Repository Infrastructure Vision for European Research (DRIVER)

In this work the influence of solid electrolyte additives on the gas sensing properties of tin oxide layers was investigated systematically for the first time. NASICON (NAtrium, Super Ionic CONductor, Na(1+x)Zr2SixP(3-x)O12; 0 <= x <= 3) was used as a model for solid electrolyte additives. The structure of that material is ideally suitable for studies of the correlation between material parameters and the gas sensitivity of the layers. In the NASICON structure the content of mob...

Hetznecker, Alexander

2005-01-01

76

Equilibrium relations in the system TiO2/V2O5/P2O5 and crystal structure of a NASICON-related vanadyl(V) titanium(IV) phosphate  

Science.gov (United States)

Vanadyl(V)-titanium-orthophosphate (VVO)TiIV6(PO4)9 is formed by solid state reactions in the temperature range 525???780 °C. At higher temperature decomposition into V2O5 and the hitherto unknown solid solution Ti(P1-xVx)2O7 (0?x?0.23; 0.30?x?0.43) is observed. The process of phase formation has been monitored by MAS-NMR (31P, 51V) spectroscopy. Equilibrium phase relations in the quaternary system TiO2/VO2.5/PO2.5 have been determined. A structure analysis from X-ray single-crystal data (P63/m (No. 176), Z=2; a=8.4438(3) Å, c=22.215(1) Å, 14 independent atoms, 87 variables, 2066 unique reflections, R1=0.032, wR2=0.084) shows the relationship of (VVO)TiIV6(PO4)9 to the NASICON structure family. In marked contrast to the other members of this family [TiIV2O9] double-octahedra and strongly distorted tetrahedral [(VV=O)O3] groups are observed besides isolated [TiIVO6] octahedra and phosphate tetrahedra. The structure model is in agreement with the results from MAS-NMR (31P, 51V) spectroscopy.

Titlbach, Sven; Hoffbauer, Wilfried; Glaum, Robert

2012-12-01

77

Electrochemical performance of all-solid-state Li batteries based LiMn{sub 0.5}Ni{sub 0.5}O{sub 2} cathode and NASICON-type electrolyte  

Energy Technology Data Exchange (ETDEWEB)

LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} thin films have been deposited on the NASICON-type glass ceramics, Li{sub 1+x+y}Al{sub x}Ti{sub 2-x}Si{sub y}P{sub 3-y}O{sub 12} (LATSP), by radio frequency (RF) magnetron sputtering followed by annealing. The films have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy. All-solid-state Li/PEO{sub 18}-Li(CF{sub 3}SO{sub 2}){sub 2}N/LATSP/LiNi{sub 0.5}Mn{sub 0.5}O{sub 2}/Au cells are fabricated using the LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} thin films and the LATSP electrolyte. The electrochemical performance of the cells is investigated by galvanostatic cycling, cyclic voltammetry (CV), potentiostatic intermittent titration technique (PITT) and electrochemical impedance spectroscopy (EIS). Interfacial reactions between LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} and LATSP occur at a temperature as low as 300 C with the formation of Mn{sub 3}O{sub 4}, resulting in an increased obstacle for Li-ion diffusion across the LiNi{sub 0.5}Mn{sub 0.5}O{sub 2}/LATSP interface. The electrochemical performance of the cells is limited by the interfacial resistance between LATSP and LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} as well as the Li-ion diffusion kinetics in LiNi{sub 0.5}Mn{sub 0.5}O{sub 2} bulk. (author)

Xie, J.; Zhao, X.B.; Cao, G.S. [Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Imanishi, N.; Zhang, T.; Hirano, A.; Takeda, Y.; Yamamoto, O. [Department of Chemistry, Faculty of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507 (Japan)

2010-12-15

78

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

79

Nuclear quadrupole interaction measurements on 181Ta in NASICON  

International Nuclear Information System (INIS)

The quadrupole interaction experienced by the 181Ta nucleus placed in substitution for Zr in the Na3Zr2Si2PO12 compound (NASICON) has been determined from gamma-ray angular correlation experiments in the temperature range 20-7000C. The asymmetry of the electric field-gradient tensor vanishes for T >approx. 2000C, which is an indication for a non-random substitution of Si4+ for P5+ ions and a high mobility of both Na(1) and Na(2) species in the rhombohedral structure. Furthermore, the results are consistent with the idea that the transition from a monoclinic to a rhombohedral structure is accompanied by a transfer of sodium ions from static interstitial positions into partially occupied Na(1) and/or Na(2) positions. (Auth.)

80

NASICON-related Na3.4Mn0.4Fe1.6(PO4)3  

Science.gov (United States)

The solid solution, sodium [iron(III)/manganese(II)] tris­(orthophosphate), Na3.4Mn0.4Fe1.6(PO4)3, was obtained using a flux method. Its crystal structure is related to that of NASICON-type compounds. The [(Mn/Fe)2(PO4)3] framework is built up from an (Mn/Fe)O6 octa­hedron (site symmetry 3.), with a mixed Mn/Fe occupancy, and a PO4 tetra­hedron (site symmetry .2). The Na+ cations are distributed over two partially occupied sites in the cavities of the framework. One Na+ cation (site symmetry -3.) is surrounded by six O atoms, whereas the other Na+ cation (site symmetry .2) is surrounded by eight O atoms. PMID:22807697

Yatskin, Michael M.; Strutynska, Nataliya Yu.; Baumer, Vyacheslav N.; Ogorodnyk, Ivan V.; Slobodyanik, Nikolay S.

2012-01-01

 
 
 
 
81

FT-IR and FT-Raman study of Nasicon type phosphates, ASnFe(PO4)3 [A=Na2, Ca, Cd].  

Science.gov (United States)

FT-Raman and FT-IR spectra of ASnFe(PO4)3 [A=Na2, Ca, Cd] were recorded and analyzed. The bands were assigned in terms of the vibrational group frequencies of SnO6 octahedral and PO4 tetrahedral. The spectral analysis shows that the symmetry of corner shared octahedral (SnO6) and the tetrahedral (PO4) are lowered from their free ion symmetry state. The presence of Fe3+ ions disrupts the S-N-O-S-N chain in the structure. This causes distortion of SnO6 and PO4 in the structure of all the compounds. Also it is seen that there are two distinct PO4 tetrahedra of different P-O bond lengths. One of these tetrahedra is linearly distorted in all the title compounds. The PO4 frequencies and bond lengths are calculated theoretically and are in agreement with the experimental values. The presence of PO4 polyanion in the structure can reduce the redox energy and hence reduce the metal oxygen covalency strength in the structure. PMID:21146455

Antony, C J; Aatiq, A; Panicker, C Yohannan; Bushiri, M Junaid; Varghese, Hema Tresa; Manojkumar, T K

2011-01-01

82

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

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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.

Fuentes, R. O.

1999-12-01

83

Electron-irradiation induced phase transformation in La1/3Zr2(PO4)3: La3+ displacement in a preserved NASICON framework  

International Nuclear Information System (INIS)

The La1/3Zr2(PO4)3 NASICON-type compound (S.G. P3-bar - neutron and X-ray diffraction experiments) is investigated by transmission electron microscopy (TEM) technique, selected area electron diffraction (SAED) and high-resolution electron microscopy (HREM), in order to study locally the lanthanum distribution. An irreversible structural transformation (P-bar -bar -bar ->P-bar c-bar ->R-bar -bar -bar ) is observed, without modification of the atomic content and cell size, as soon as the phase is illuminated by the electron beam. The progressive disappearance of the spots which do not check the R conditions on the SAED patterns is clearly shown along two zone axis, [001] and [100]. This transformation implies the displacement of the two La3+ cations in a preserved classical [Zr2(PO4)3]- network. This interesting behavior is in good agreement with the La3+ ionic conductivity observed in La1/3Zr2(PO4)3 (4.09x10-7Scm-1 at 700 deg. C). To our knowledge, this is the first time that a complete TEM study is done on a NASICON-type phase

84

Electron-irradiation induced phase transformation in La 1/3Zr 2(PO 4) 3: La 3+ displacement in a preserved NASICON framework  

Science.gov (United States)

The La 1/3Zr 2(PO 4) 3 NASICON-type compound (S.G. P3¯ - neutron and X-ray diffraction experiments) is investigated by transmission electron microscopy (TEM) technique, selected area electron diffraction (SAED) and high-resolution electron microscopy (HREM), in order to study locally the lanthanum distribution. An irreversible structural transformation (P - - - ? P - c - ? R - - -) is observed, without modification of the atomic content and cell size, as soon as the phase is illuminated by the electron beam. The progressive disappearance of the spots which do not check the R conditions on the SAED patterns is clearly shown along two zone axis, [001] and [100]. This transformation implies the displacement of the two La 3+ cations in a preserved classical [Zr 2(PO 4) 3] - network. This interesting behavior is in good agreement with the La 3+ ionic conductivity observed in La 1/3Zr 2(PO 4) 3 (4.09×10 -7 S cm -1 at 700 °C). To our knowledge, this is the first time that a complete TEM study is done on a NASICON-type phase.

Crosnier-Lopez, M. P.; Barre, M.; Le Berre, F.; Fourquet, J. L.

2006-08-01

85

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)

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

Arbi, K; París, M A; Sanz, J

2011-10-21

86

Part 222: sodium conductivity enhancement along domain and grain boundaries nasicon solid electrolytes  

International Nuclear Information System (INIS)

Bulk, grain, and domain boundary sodium ion conductivity data are presented for nasicon single crystals and ceramics of composition Na/sub 1+x+4y/Zr/sub 2-y/Si/sub x/P/sub 3-x/O12 (x=0-3, y=0-0.2). For silicate-rich compositions the ''crystals'' are built out of domains and the conductance of the resulting domain bundaries are shown to determine the macroscopically observed conductivity. Grain boundaries in ceramics behave in a similar way. A structural explanation of the observed phenomena is suggested

87

Raman study of the inorganic polymer ? superionic nasicon tranformation : dynamical, static orientational disorder and superionic conductivity  

Science.gov (United States)

Optically clear amorphous monolithes, powders or ceramics can be prepared by chemical polymerisation and low temperature thermal treatments. Polarized Raman spectra exhibit a great orientational disorder, characteristic of a glassy structure. In the case of NASICON × = 2 composition, which crystallized above 900°C, a static part of tetrahedra orientational disorder remains and decreases only with thermal treatments below the melting point; an other part, dynamical, increases drastically at the monclinic ? rhombohedral transition (˜150°C). This behaviour, also observed on pure phosphate single crystals, Na 3Sc 2(PO 4) 3, is related to the superionic conductivity.

Colomban, Ph.

1986-03-01

88

Equilibrium relations in the system TiO{sub 2}/V{sub 2}O{sub 5}/P{sub 2}O{sub 5} and crystal structure of a NASICON-related vanadyl(V) titanium(IV) phosphate  

Energy Technology Data Exchange (ETDEWEB)

Vanadyl(V)-titanium-orthophosphate (V{sup V}O)Ti{sup IV}{sub 6}(PO{sub 4}){sub 9} is formed by solid state reactions in the temperature range 525{<=}{theta}{<=}780 Degree-Sign C. At higher temperature decomposition into V{sub 2}O{sub 5} and the hitherto unknown solid solution Ti(P{sub 1-x}V{sub x}){sub 2}O{sub 7} (0{<=}x{<=}0.23; 0.30{<=}x{<=}0.43) is observed. The process of phase formation has been monitored by MAS-NMR ({sup 31}P, {sup 51}V) spectroscopy. Equilibrium phase relations in the quaternary system TiO{sub 2}/VO{sub 2.5}/PO{sub 2.5} have been determined. A structure analysis from X-ray single-crystal data (P6{sub 3}/m (No. 176), Z=2; a=8.4438(3) A, c=22.215(1) A, 14 independent atoms, 87 variables, 2066 unique reflections, R1=0.032, wR2=0.084) shows the relationship of (V{sup V}O)Ti{sup IV}{sub 6}(PO{sub 4}){sub 9} to the NASICON structure family. In marked contrast to the other members of this family [Ti{sup IV}{sub 2}O{sub 9}] double-octahedra and strongly distorted tetrahedral [(V{sup V}=O)O{sub 3}] groups are observed besides isolated [Ti{sup IV}O{sub 6}] octahedra and phosphate tetrahedra. The structure model is in agreement with the results from MAS-NMR ({sup 31}P, {sup 51}V) spectroscopy. - Graphical abstract: (V{sup V}O)Ti{sup IV}{sub 6}(PO{sub 4}){sub 9} belongs to the NASICON structure family. Its structure contains [Ti{sup IV}{sub 2}O{sub 9}] double-octahedra and unprecedented, strongly distorted tetrahedral [(V{sup V}=O)O{sub 3}] groups, in stark contrast to other members of this family. The structure model is in agreement with the results from MAS-NMR ({sup 31}P, {sup 51}V) spectroscopy. Highlights: Black-Right-Pointing-Pointer Equilibrium relations for the subsolidus have been established for the system TiO{sub 2}/V{sub 2}O{sub 5}/P{sub 2}O{sub 5}. Black-Right-Pointing-Pointer Phase formation has been monitored by XRPD as well as by {sup 31}P- and {sup 51}-MAS-NMR. Black-Right-Pointing-Pointer A solid solution Ti(P{sub 1-x}V{sub x}){sub 2}O{sub 7} exists up to x=0.43 with a miscibility gap at 0.23{<=}x{<=}0.30. Black-Right-Pointing-Pointer The crystal structure of the new NASICON-related phosphate (V{sup V}O)Ti{sup IV}{sub 6}(PO{sub 4}){sub 9} is reported. Black-Right-Pointing-Pointer The crystal structure contains the unprecedented [(V=O)O{sub 3}] group.

Titlbach, Sven; Hoffbauer, Wilfried [Institut fuer Anorganische Chemie der Universitaet Bonn, Gerhard-Domagk-Str. 1, D-53121 Bonn (Germany); Glaum, Robert, E-mail: rglaum@uni-bonn.de [Institut fuer Anorganische Chemie der Universitaet Bonn, Gerhard-Domagk-Str. 1, D-53121 Bonn (Germany)

2012-12-15

89

Preparation of LiMn{sub 2}O{sub 4} thin-film electrode on Li{sub 1+x}Al{sub x}Ti{sub 2-x}(PO{sub 4}){sub 3} NASICON-type solid electrolyte  

Energy Technology Data Exchange (ETDEWEB)

An interface consisting of LiMn{sub 2}O{sub 4} thin-film (1 {mu}m thick) electrode and Li{sub 1+x}Al{sub x}Ti{sub 2-x}(PO{sub 4}){sub 3}-based NASICON-type solid electrolyte (LTP) was prepared by a sol-gel coating method. The submicron-sized pores were involved in the thin film, and the porosity of the film was relatively high. The prepared solid-solid electrochemical interface was evaluated by cyclic voltammetry and galvanostatic charge-discharge test. Two reversible redox peaks were observed at 4.0 and 4.1 V versus Li/Li{sup +} in the cyclic voltammogram due to the redox of Mn{sup 3+/4+}. The LiMn{sub 2}O{sub 4} thin-film electrode on LTP exhibited a discharge capacity of 80 mA h g{sup -1} at 0.1 C rate. (author)

Dokko, Kaoru; Kanamura, Kiyoshi [Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397 (Japan); CREST, Japan Science and Technology Agency, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Hoshina, Keigo; Nakano, Hiroyuki [Department of Applied Chemistry, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-ohsawa, Hachioji, Tokyo 192-0397 (Japan)

2007-12-06

90

An amorphous LiCo{sub 1/3}Mn{sub 1/3}Ni{sub 1/3}O{sub 2} thin film deposited on NASICON-type electrolyte for all-solid-state Li-ion batteries  

Energy Technology Data Exchange (ETDEWEB)

Amorphous LiCo{sub 1/3}Mn{sub 1/3}Ni{sub 1/3}O{sub 2} thin films were deposited on the NASICON-type Li-ion conducting glass ceramics, Li{sub 1+x+y}Al{sub x}Ti{sub 2-x}Si{sub y}P{sub 3-y}O{sub 12} (LATSP), by radio frequency (RF) magnetron sputtering below 130 C. The amorphous films were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The Li/PEO{sub 18}-Li(CF{sub 3}SO{sub 2}){sub 2}N/LATSP/LiCo{sub 1/3}Mn{sub 1/3}Ni{sub 1/3}O{sub 2}/Au all-solid-state cells were fabricated to investigate the electrochemical performance of the amorphous films. It was found that the low-temperature deposited amorphous cathode film shows a high discharge voltage and a high discharge capacity of around 130 mAh g{sup -1}. (author)

Xie, J. [Department of Chemistry, Faculty of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507 (Japan); Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027 (China); Imanishi, N.; Zhang, T.; Hirano, A.; Takeda, Y.; Yamamoto, O. [Department of Chemistry, Faculty of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507 (Japan)

2010-09-01

91

Influence of thermal cycling on properties of NASICON  

International Nuclear Information System (INIS)

The influence of thermal cycling on the bulk and grain boundary conductivities and on microhardness of Na3Zr2Si2PO12 (NASICON) has been investigated. The electrical conductivity of calcined and sintered specimens was measured in the temperature range 293 to 673 K before and after approximately 300 cycles between 373 and 473 K. The grain conductivity was found to be much higher after thermal cycling. The microhardness of the sample drapped from 580 to 320 kp/mm2

92

Reactivity of NASICON with water and interpretation of the detection limit of a NASICON based Na(+) ion selective electrode.  

Science.gov (United States)

The leaching of Na(+) ions from NASICON of composition Na(3)Zr(2)Si(2)PO(12) to the aqueous solution was evidenced. The origin of the Na(+) leaching was studied using Na(+) concentration and pH measurements as well as solution and X-ray analyses. The Na(+) released was mainly attributed to the dissolution of a second phase, predominantly amorphous. The rate of Na(+) release was found to be dependent on the inverse of the square of the particle size. It is proposed that it is controlled by diffusion within the particle. An effective diffusion coefficient was deduced to be of the order of 5x10(-10) cm(2) s(-1). The nature of the detection limit of the NASICON based Na(+) ion selective electrodes is discussed. PMID:18967467

Mauvy, F; Siebert, E; Fabry, P

1999-02-01

93

A new NASICON-type polyanion, Li{sub x}Ni{sub 2}(MoO{sub 4}){sub 3} as 3-V class positive electrode material for rechargeable lithium batteries  

Energy Technology Data Exchange (ETDEWEB)

This paper presents our success in synthesizing a new framework type Li{sub x}Ni{sub 2}(MoO{sub 4}){sub 3} (0=structure as confirmed by X-ray diffraction (XRD) and were characterized by electrochemical techniques in order to elucidate the suitability of this new material as positive electrode material in rechargeable lithium-containing batteries. The morphology of the heated product was found to be composed of soft agglomerates embedded by submicrometre spherical grains. The electrode-active character of the new material was examined in a two-electrode configuration employing a Li{sup +} non-aqueous electrolyte environment. Slow scan cyclic voltammetry (SSCV) revealed the redox property of the material between the voltage window 3.5 and 1.5 V. Galvanostatic tests exhibited a well discernible discharge-charge profile with a reversible capacity of 170 mA h/g over the potential window of 3.5-1.5 V.

Begam, K.M.; Michael, M.S.; Prabaharan, S.R.S. [Advanced Power Sources Laboratory, Multimedia University, Faculty of Engineering, Center for Smart Systems and Innovation, Cyberjaya 63100 (Malaysia); Taufiq-Yap, Y.H. [Department of Chemistry, Universiti Putra Malaysia, 43400 Serdang, Selangor D.H. (Malaysia)

2004-08-31

94

Superstructure of a NASICON-related compound NH 4Ti 2P 3O 12  

Science.gov (United States)

Ion-pathways in a NASICON-related compound NH 4Ti 2P 3O 12 (hexagonal, a = 0.832 and c = 2.34 nm) are directly observed by means of high-resolution transmission electron microscopy. When the composition changes to Ti 4P 6O 23 due to the deammoniation as well as dehydration of heating at 770°C, a supercell with the dimensions of A ? 2a and C ? 2c is constructed. A model of the superstructure is proposed based on the arrangement of oxygen vacancies as well as the induced distortion of the TiO 6 octahedra, retaining the three-dimensional network in the starting structure.

Horiuchi, Shigeo; Ono, Akira

1986-05-01

95

Influence of Si/P ordering on Na+ transport in NASICONs.  

Science.gov (United States)

The influence of Si/P ordering on Na(+) transport in the high conducting NASICON composition, Na3Zr2Si2PO12, is investigated using molecular dynamics simulation. The study demonstrates that the Na(+) conductivity in the system changes by more than an order of magnitude depending on the Si/P order in the structure. This rather surprising observation is attributed to the modulations in the electrostatic potential energy landscape along the conduction channel originating out of the increased coulombic repulsion of Na(+) with P(5+) ions compared to Si(4+). The study reveals the significance of the order of framework cations in fast ion transport in solids with aliovalent substitutions. PMID:23443462

Roy, Supriya; Kumar, P Padma

2013-04-14

96

Síntesis mediante química sol gel de compuestos Li1+xMiiixTi2-x(PO43 con estructura tipo Nasicon. Estudio de la relación microestructura-propiedades eléctricas  

Directory of Open Access Journals (Sweden)

Full Text Available Compounds of formula Li1+xMIIIxTi2-x(PO43 with MIII = 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, LiTi2(PO43 until values of 9x10-4 S cm-1 at room temperature in the chromium-doped material.Haciendo uso de la química sol-gel, se han preparado ortofosfatos de composición LiTi2(PO43 y Li1.05(Cr/Fe0.05Ti1.95(PO43 a temperaturas moderadas mediante el método Pechini. Estas fases han sido caracterizadas estructural y microestructuralmente por difracción de rayos X de polvo y microscopía electrónica de barrido (SEM, encontrándose que todas cristalizan en una estructura tipo NASICON, con parámetros de red muy similares. El dopaje con Fe y Cr permite aumentar la densidad de las muestras en la sinterización, mejorando de forma apreciable su conductividad iónica. Se ha observado un incremento de hasta cuatro órdenes de magnitud en la conductividad a temperatura ambiente obteniéndose una energía de activación de 0.29 eV para el material dopado con Cr.

Santamaría, J.

2010-02-01

97

Restrictions to obtain NASICON by a ceramic route  

Directory of Open Access Journals (Sweden)

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.

Fuentes, R. O.

2004-08-01

98

Study of defects in Zr lacunar Nasicon crystals  

International Nuclear Information System (INIS)

Samples of Nasicon compounds NaxZr2-ySi3-zPzO12, with x-4y+z=4, were investigated by radioluminescence and thermoluminescence experiments. It has been found that disorder in the Zr lacunar sublattice originates charged defects active as centres of electron-hole radiative recombinations in excited crystals. The analysis of radio luminescent spectra shows that the minimum displacements of Na+ ions exceed 5 A. This results yields information on the paths of Na+ ions in the ionic conduction of these materials

99

Ionic conductivity of LiHf2(PO4)3 with NASICON-type structure and its possible application as electrolyte in lithium batteries  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este trabalho reporta medidas de condutividade iônica realizadas para o LiHf2(PO4)3 calcinado a 1100 °C. As respostas devidas aos grãos - interior e junção - puderam ser identificadas tanto nas curvas de impedância, como na parte real das curvas de condutividade vs. freqüência. A energia de ativação [...] , associada ao movimento dos íons Li+ no interior dos grãos, é 0,33 eV, enquanto que aquela associada à condutividade total cc, está na faixa de 0,36-0,47 eV. os resultados desta última dependem da contribuição relativa devida ao interior e à junção de grão. A possível aplicação do LiHf2(PO4)3 como eletrólito foi testada para a pilha Li/LiHf2(PO4)3/LiMn2O4. Observou-se que o potencial de equilíbrio aumenta de 0,076 V a 2,217 V, quando a temperatura varia de 28 a 148 °C. Abstract in english The ionic conductivity of LiHf2(PO4)3 calcined at 1100 °C has been measured. Grain interior and grain boundary responses can be distinguished in the impedance plots as well as in the real part of conductivity vs frequency plots. The activation energy associated with the motion of Li+ ions inside the [...] grains is 0.33 eV while the activation energy corresponding to the total dc conductivity changes from 0.36 to 0.47 eV, depending on the relative contribution of grain interior and grain boundary. The possible application of LiHf2(PO4)3 as an electrolyte has been tested in the Li/LiHf2(PO4)3/LiMn2O4 cell. The equilibrium potential increases from 0.076 V to 2.217 V when the temperature is raised from 28 to 148 ºC.

A, Martínez-Juárez; J.M, Amarilla; J.E, Iglesias; J.M, Rojo.

100

Ionic conductivity of LiHf2(PO4)3 with NASICON-type structure and its possible application as electrolyte in lithium batteries  

Scientific Electronic Library Online (English)

Full Text Available SciELO Brazil | Language: English Abstract in portuguese Este trabalho reporta medidas de condutividade iônica realizadas para o LiHf2(PO4)3 calcinado a 1100 °C. As respostas devidas aos grãos - interior e junção - puderam ser identificadas tanto nas curvas de impedância, como na parte real das curvas de condutividade vs. freqüência. A energia de ativação [...] , associada ao movimento dos íons Li+ no interior dos grãos, é 0,33 eV, enquanto que aquela associada à condutividade total cc, está na faixa de 0,36-0,47 eV. os resultados desta última dependem da contribuição relativa devida ao interior e à junção de grão. A possível aplicação do LiHf2(PO4)3 como eletrólito foi testada para a pilha Li/LiHf2(PO4)3/LiMn2O4. Observou-se que o potencial de equilíbrio aumenta de 0,076 V a 2,217 V, quando a temperatura varia de 28 a 148 °C. Abstract in english The ionic conductivity of LiHf2(PO4)3 calcined at 1100 °C has been measured. Grain interior and grain boundary responses can be distinguished in the impedance plots as well as in the real part of conductivity vs frequency plots. The activation energy associated with the motion of Li+ ions inside the [...] grains is 0.33 eV while the activation energy corresponding to the total dc conductivity changes from 0.36 to 0.47 eV, depending on the relative contribution of grain interior and grain boundary. The possible application of LiHf2(PO4)3 as an electrolyte has been tested in the Li/LiHf2(PO4)3/LiMn2O4 cell. The equilibrium potential increases from 0.076 V to 2.217 V when the temperature is raised from 28 to 148 ºC.

A, Martínez-Juárez; J.M, Amarilla; J.E, Iglesias; J.M, Rojo.

1997-06-01

 
 
 
 
101

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

102

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

Science.gov (United States)

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.

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

2010-04-01

103

A time of flight neutron powder rietveld refinement study at elevated temperature on a monoclinic near-stoichiometric NASICON  

Science.gov (United States)

Time of flight neutron powder data were collected at elevated temperatures on a sample of NASICON of composition Na 3.17Zr 1.93Si 1.9P 1.1O 12. This sample, prepared by reheating a commerically available NASICON to minimize the ZrO 2 impurity, has been previously structurally refined from room temperature neutron diffraction data collected at Argonne National Laboratory. Conductivity measurements show a cusp at ca. 170°C 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 391°C. 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 a disordering of the sodium ions and a change in conduction pathways which lowers the barriers to ion movement.

Rudolf, P. R.; Clearfield, A.; Jorgensen, J. D.

1988-01-01

104

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

105

Preparation, Structural Characterization and Ionic Conductivity Studies of Calcium Doped LiZr2(PO4)3  

Science.gov (United States)

Compounds with NASICON-type structure, Li1+2x (CaxZr2-x)(PO4)3, (x = 0.1 and 0.15) are prepared by the high temperature solid state reaction and are characterized by Rietveld refined X-ray diffraction, scanning electron microscopy and BET surface area techniques. Ca-substitution stabilizes the rhombohedral structure of the NASICON-phase. Ionic conductivities, ? (ionic) were determined in the temperature range of 27-300 °C by impedance spectroscopy. Results showed a ? ionic (total) at 300K of 0.4 × 10-6 S cm-1 and 0.2 × 10-6 S cm-1, respectively, for x = 0.1 and 0.15. The activation energy (Ea) = 0.57eV and 0.61eV, respectively in the temperature range 27-300 °C.

Prabu, M.; Reddy, M. V.; Selvasekarapandian, S.; Rao, G. V. Subba; Chowdari, B. V. R.

2013-07-01

106

Positron annihilation studies on nasicon analogues containing cation vacancies  

International Nuclear Information System (INIS)

Positron annihilation studies were carried out on the Nasicon analogue Na2(La, Al)Zr(PO4)3 compound for three different concentrations (2.2, 2.8 and 5.2 by wt.%) of ZrO2 in the nutrient. Angular correlation study of annihilated photons reveals that the defect concentration is maximum for 2.8(wt.%) of ZrO2. Further, positron lifetime studies indicate that the positrons are trapped at cation vacancies. Application of a two state trapping model to this system made it possible to evaluate the lifetime of positrons in the Bloch state and of positrons trapped at cation vacancies. (author). 16 refs., 4 figs

107

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

Science.gov (United States)

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.

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

2014-02-01

108

Lithium exchange processes in the conduction network of the Nasicon LiTi2-xZrx(PO4)3 Series (0 < or = x < or = 2).  

Science.gov (United States)

Structural sites occupied by lithium in the rhombohedral LiTi2-xZrx(PO4)3 series (0 Nasicon conduction network has been deduced. At high temperatures, analyzed phases tend toward a disordered rhombohedral phase, in which both M1 and M1/2 sites are equally populated and in which lithium mobility is favored by the existence of vacant M1 sites. According to this study, this phase can also be obtained by substituting Ti by Zr in the LiTi2-xZrx(PO4)3 series. PMID:16570941

Arbi, K; París, M A; Sanz, J

2006-04-01

109

Effect of decomposition on the densification and properties of nasicon ceramic electrolytes  

International Nuclear Information System (INIS)

Nasicon ceramic electrolytes were processed and characterized using a number of different techniques. The materials were sintered at T = 11000C to 13750C. Results of this work demonstrate that Nasicon ceramics with compositions around x = 2 (i.e. Na3Zr2Si2PO12), are not monophase, possess poor mechanical strength and an anomalous thermal expansion behavior, and are subject to chemical and phase instability during densification at high temperatures. Wet-chemical techniques, X-ray diffraction, and SEM analyses were used to observe the phase and chemical decomposition of these materials. The products of this decomposition process are correlated with the poor physical properties

110

The study of hydronium NASICON conductivity with deuterium  

International Nuclear Information System (INIS)

The ionic conductivity of the bulk phase of bonded hydronium NASICON (HyceramTM) was measured at equilibrium with an H2O/N2 and then a D2O/N2 atmosphere, each at 100% relative humidity and 75% relative humidity over the temperature range 25-50deg C. At 100% relative humidity and 25deg C, the protonic system had a bulk conductivity of 5.0x10-4 S/cm and an activation energy of 17.3kJ mole; the same sample, when deuterated, had a bulk conductivity of 2.2x10-4 S/cm and an activation energy of 19.3 kJ/mole. At 75% relative humidity and 25deg C, the conductivity of the protonated system decreased to 1.4x10-4 S/cm with an activation energy of 24.1 kJ/mole. The deuterated sample at 75% relative humidity had a bulk conductivity of 5.4x10-5 S/cm with an activation energy of 26.0 kJ/mole. The isotope effect suggested a proton hopping (Grotthus) mechanism as the means by which the protons pass through the lattice. (author). 18 refs.; 3 figs.; 1 tab

111

Na+ and Li+ NASICON Superionic Conductors Thick Films  

Science.gov (United States)

For microionic applications, superionic conductors have been elaborated in the form of thick films, using silk-screen printable powders. Na3Zr2Si2PO12, Na3.1Zr1.55Si2.3P0.7O11 and Li0.8Zr1.8Ta0.2(PO4)3 compositions are synthesized by a sol-gel process involving hydrolysis-polycondensation reactions of metal-organic alcoholic solutions. A thermal treatment (600°C-800°C) allows to obtain very fine particles (NASICON phase. Inks are prepared with these powders, an organic binder, volatile fluidifying agents and mineralizers. The layers, about 50 ?m in thickness, are achieved by successive deposits and sinterings (950°C-1050°C) onto alumina substrates. Films conductivity is determined by the complex impedance method. Values measured at 300°C (Na+: ?˜10-2 ?-1cm-1, EA{=}0.25 eV, Li+: ?˜5 10-4 ?-1cm-1, EA{=}0.5 eV) reach those obtained with well-densified ceramics. An anisotropic behaviour related to microstructure is pointed out.

Perthuis, H.; Velasco, G.; Colomban, Ph.

1984-05-01

112

Term Encoding of Typed Feature Structures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This paper presents an approach to Prolog-style term encoding of typed feature structures. The type feature structures to be encoded are constrained by appropriateness conditions as in Carpenter's ALE system. But unlike ALE, we impose a further independently motivated closed-world assumption. This assumption allows us to apply term encoding in cases that were problematic for previous approaches. In particular, previous approaches have ruled out multiple inheritance and furth...

Gerdemann, Dale

1995-01-01

113

Determination of the p-electronic conduction parameter of NASICON by potentiometric measurements  

International Nuclear Information System (INIS)

Using the galvanic cell: Pt vertical bar Au,CO2,O2 vertical bar aNa''' Na2CO3(Au) vertical bar aNa''NASICON vertical bar aNa'FeO+NiO(borateglass)|FeNi(48)|Au |Pt the p-electronic conduction parameter a-bar of NASICON was characterized as a function of the sodium activity aNa'' and the temperature. For that purpose, the isothermal voltage response to successive variations of aNa'' by changing the composition of the CO2-O2 gas mixture was evaluated by a non-linear regression procedure. Within the temperature range under investigation (300-620 deg. C) it holds that: loga+ =11.076+/-0.1-(18278.0+/-1100)KT(T=+=-3.519+/-1.7-(7904+/-1400)KT(500 deg. C=2 sensor with NASICON as solid electrolyte the sodium activity prevailing at the measuring electrode is outside the ionic domain of the electrolyte. This is in apparent contradiction to most of the literature reports on the behavior of such gas sensors, but confirms previous findings on the extent of the electronic conductivity in Na-beta-alumina under comparable conditions

114

Recycling Caustic from LAW Stream using NaSICON Membrane based Electrochemical Technology  

International Nuclear Information System (INIS)

Ceramatec Inc. has developed and demonstrated an efficient electrochemical technology to separate sodium from Low Activity Waste (LAW) streams using a NaSICON (Sodium Super Ionic Conductor) ceramic membrane based electrolytic process. The NaSICON membrane process separates sodium contained in LAW streams thereby significantly reducing the quantity of LAW glass to be produced. The separated sodium is regenerated in the form of 'clean' sodium hydroxide and reused on site. Laboratory scale reliability and lifetime tests have been conducted at Ceramatec Inc. with multiple simulants representing baseline chemistries at site and have demonstrated the ability to recycle sodium from LAW streams. Three specific evaluations were conducted at Pacific Northwest National Laboratory (PNNL) to investigate the ability of NaSICON membrane based electrolytic cells to separate sodium from actual LAW streams. The average sodium transport efficiencies were 93% (non-radioactive test) and 99% (two radioactive tests). A maximum recoverable sodium quantity could be predicted by combining both an aluminate solubility model and a gibbsite crystal growth rate. Testing shows cell voltages were relatively stable until saturation ratios exceeded 9 and the cell was successfully operated at saturation ratios as high as 12. No transport of any cations or anions was detected except for Na and Cs-137. Decontamination factors on the order of 2000 were observed with respect to Cs-137. (authors)th respect to Cs-137. (authors)

115

The preparation and characterization of dense, highly conductive Na5GdSi4O12 nasicon (NGS)  

DEFF Research Database (Denmark)

Na5GdSi4O12 has been prepared via conventional ball-milling technique and through spray-freezing/freeze-drying. The ball-milled materials were calcined at 700°C or 925°C and sintered at 1050°C/3.5h to 89% dense multiphase ceramics. Spray-frozen/freeze-dried powders were calcined at 530°C and sintered at 1050°C/25 min to 99 ± 1% theoretical density. The latter material was single-phase NGS nasicon with a 300°C resistivity of 3.8 ?·cm, an activation energy for Na+-conduction of 4.4 kcal/mol, a flexural strength of 105 MPa, a duplex grain structure with average sizes 0.4 ?m and 3 ?m and a unique linear thermal expansion coefficient (25–540°C; ? = 12.6 × 10?6/°C±4%).

Bentzen, Janet Jonna; Nicholson, Patrick S.

1980-01-01

116

Syntheses, Properties and Applications of Framework Titanium Phosphates with Open Structures  

Science.gov (United States)

A new layered hydrogen titanium phosphate (HTP) was synthesized by ion exchange of a precursor material NMe_4TP. This precursor, which was prepared from a hydrothermal reaction employing tetramethylammonium as a templating cation, also has a layered structure. The chemical formula of HTP was proposed as TiO_2 (H_2PO_4)(H _3O). This was derived using ^{31}P magic angle spinning solid state NMR, structural considerations, and other supplemental methods. A model for the structure of HTP was proposed in this study. HTP is capable of undergoing amine and redox lithium intercalations and the reactions show excellent reversibility. Each formula unit of HTP can take up one amine molecule or two lithium cations. Amines intercalate into HTP with a bilayer conformation and tilt at an angle of about 55 degrees relative to the layer slabs. Metal cations can also be incorporated into HTP under carefully controlled pH conditions or from the amine intercalates. The conductivity of the lithium cations intercalated into HTP was studied by ac impedance spectroscopy and is comparable to that of the NASICON type compounds. A Li/LiClO _4/HTP electrochemical cell was constructed and its discharge was studied. The discharge potential ranges between 2.6 and 1.8 volts and the energy density of this cell was estimated to be about 550 W*h/kg for the pure HTP material. The three dimensional titanium phosphates with the NASICON structure were also studied in this work. The hydrothermal process was used and investigated for the synthesis of MTi_2(PO_4 )_3, where M = Li ^+, Na^+, K ^+, Ag^+, or Cu ^+. Pure products were obtained under milder conditions than reported before. A comparison on the syntheses and properties of these NASICON compounds prepared from different processes is given.

Li, Yingjeng James

117

Detection of very low concentration of water in ethanol by using NASICON probe  

Science.gov (United States)

NASICON based low cost, highly sensitive sensor probe for detection of very small content of the water nearly ppm level in ethanol has been fabricated and characterized. The sensor utilizes the electrochemical cell method for detection of water content in ethanol. The results indicate nearly linear variation of emf with increase in water content upto 10 % with a sensitivity of 0.001mV per ppm. Such a high value of sensitivity is extremely useful in detection of water in medical science and chemical industries where ethanol is used as an organic solvent.

Yadav, Parul; Bhatnagar, M. C.

2013-02-01

118

Conversion of Type of Quantum Well Structure  

Science.gov (United States)

A method for converting a Type 2 quantum well semiconductor material to a Type 1 material. A second layer of undoped material is placed between first and third layers of selectively doped material, which are separated from the second layer by undoped layers having small widths. Doping profiles are chosen so that a first electrical potential increment across a first layer-second layer interface is equal to a first selected value and/or a second electrical potential increment across a second layer-third layer interface is equal to a second selected value. The semiconductor structure thus produced is useful as a laser material and as an incident light detector material in various wavelength regions, such as a mid-infrared region.

Ning, Cun-Zheng (Inventor)

2007-01-01

119

Polar Structures in Late-Type Galaxies  

Science.gov (United States)

A common point of view is that stable polar structures are mainly present in the early-type galaxies lacking dense gas in their host disks. However, nuclear, as well as external polar rings and disks also exist in the late-type hosts, including gas-rich dwarf galaxies. Using the 3-dimensional spectroscopic observations of these objects we can derive the rotation properties of the gas components separately in the main and polar planes. The most detailed picture of the gas kinematics and mass distribution properties could be obtained from the combination of optical (H II) and radio (H I) data sets. I briefly review the results of such studies, including the observations of the direct interaction between the multi-spin gas components.

Moiseev, A.

2014-05-01

120

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

 
 
 
 
121

Tin clathrates with the type II structure.  

Science.gov (United States)

For a very long time, Ba(16)Ga(32)Sn(104) has been the sole representative of tin clathrates with the type II structure. Herein, we present several new members of this structural family: Cs(8)Ba(16)Ga(39.7(3))Sn(96.3(3)), Rb(9.9(5))Ba(13.3(2))Ga(36.4(3))Sn(99.6(3)), and K(2.0(4))Ba(14.0(4))Ga(30.4(2))Sn(105.6(4)). The successful synthesis of these novel compounds was facilitated through the use of alkali and alkaline-earth metals, which selectively fill the available cages. PMID:23327674

Schäfer, Marion C; Bobev, Svilen

2013-02-01

122

Complex impedance analysis of the ionic conductivity of the material conductor: Nasicon  

International Nuclear Information System (INIS)

Full text.The ionic conductivity of pressed pellets of Nasicon, Na1+xSixZr2P3-xO12 (1,4 +, have been determined by the measurement of their complex impedance in the range: 5 hz to 13 MHz. The electrodes were graphite layers and the voltage signal was chosen in the linear condition (0,1 volt). In most cases the intergrain resistance was as high or higher than the grain resistance. As mentioned by Bayard and al: for examples X = 2 sintered at 1000 celsius degree one semi-circle is observed in a Nyquist diagram. For examples sintered at 1200 celsius degree, there are generally two semi-circles. The semi-circle observed at low frequency (about 10 to 100 Khz) is certainly due to a grain boundary phase (according to x-ray an microprobe analysis)

123

Noise of surface bio-potential electrodes based on NASICON ceramic and Ag-AgCl.  

Science.gov (United States)

The electrochemical noise from dry NASICON-based surface electrodes and pregelled Ag-AgCl electrodes is evaluated in saline solutions and on the skin. The electrochemical noise from the electrode/electrolyte interface is found to be negligible (less than 1 microV peak to peak). On the skin, the noise level is highly dependent on the patient. At high frequencies, the skin/electrode interface noise is equal to 'thermal noise' and can be related to the real part of the skin/electrode impedance. At low frequencies (F < 100 Hz), excess noise is observed that varies as f-2. It is tentatively ascribed to a non-stationary process or noise of electrochemical origin due to the ionic nature of the skin. The contribution of residual EMG signal of low amplitude (5 microV peak to peak) is suggested for electrodes with large surface area. PMID:9039749

Gondran, C; Siebert, E; Yacoub, S; Novakov, E

1996-11-01

124

Caustic Recycle from Hanford Tank Waste Using NaSICON Ceramic Membrane Salt Splitting Process  

International Nuclear Information System (INIS)

A family of inorganic ceramic materials, called sodium (Na) Super Ion Conductors (NaSICON), has been studied at Pacific Northwest National Laboratory (PNNL) to investigate their ability to separate sodium from radioactively contaminated sodium salt solutions for treating U.S. Department of Energy (DOE) tank wastes. Ceramatec Inc. developed and fabricated a membrane containing a proprietary NAS-GY material formulation that was electrochemically tested in a bench-scale apparatus with both a simulant and a radioactive tank-waste solution to determine the membrane performance when removing sodium from DOE tank wastes. Implementing this sodium separation process can result in significant cost savings by reducing the disposal volume of low-activity wastes and by producing a NaOH feedstock product for recycle into waste treatment processes such as sludge leaching, regenerating ion exchange resins, inhibiting corrosion in carbon-steel tanks, or retrieving tank wastes

125

Cation mobility in NASICON compounds Li1-xZr2-xNbx(PO4)3 and Li1+xZr2-xScx(PO4)3  

International Nuclear Information System (INIS)

Compounds featuring NASICON structure of the composition Li1-xZr2-xNbx(PO4)3 and Li1+xZr2-xScx(PO4)3 were studied by the method of X-ray phase analysis and 7Li and 31P NMR. Structure of Li0.8Zr1.8Nb0.2(PO4)3 was refined on the basis of X-ray powder pattern. It is shown that cationic disordering in LiZr2(PO4)3 is stimulated both by cationic vacancies and interstitial atoms formation. The cationic vacancies are characterized by a higher mobility. The level of intrinsic disordering was estimated and the Frenkel constant for the compound was calculated

126

Types and Functions of Coastal Structures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Burcharth, H. F.; A Hughes, Steven

2003-01-01

127

Types and Functions of Coastal Structures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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.

Burcharth, H. F.; A Hughes, Steven

2005-01-01

128

Comments on structural types of toroidal carbon nanotubes  

CERN Document Server

We clarify the relationships between the eight structural types of toroidal carbon nanotubes (TCNTs), which can be identified as the eight corners of a cube of structural transformation. The four families with Dnh symmetry can be related by rim rotations, and the same is true for those with Dnd symmetries. These two sets are then connected by horizontal shiftings, thereby completing the cube. Moreover, we further point out that there are five more highly symmetric Dnh structural types that can be derived from performing the generalized Stone-Wales transformatoin on certain TCNTs with Dnh structural types.

Chuang, Chern; Jin, Bih-Yaw

2012-01-01

129

Caustic Recycle from Hanford Tank Waste Using NaSICON Ceramic Membranes  

International Nuclear Information System (INIS)

A sodium (Na) Super Ion Conductor (NaSICON), has been studied at Pacific Northwest National Laboratory (PNNL) to investigate their ability to separate sodium from radioactively contaminated sodium salt solutions for treating U.S. Department of Energy (DOE) tank wastes. Ceramatec Inc. developed and fabricated a membrane disk containing a proprietary NAS-GY material formulation that was electrochemically tested in a bench-scale apparatus with both a simulant and a radioactive tank-waste solution to determine the membrane performance when removing sodium from DOE tank wastes. Implementing this sodium separation process can result in significant cost savings by reducing the disposal volume of low-activity wastes and by producing a 19M NaOH feedstock product for recycle into waste treatment processes such as sludge leaching, regenerating ion exchange resins, inhibiting corrosion in carbon-steel tanks, or retrieving tank wastes. In actual waste tests, average sodium transport rates of 10.3 kg/day/m2 were achieved at average sodium transport efficiencies of 99%. The membrane was found to be highly selective to sodium ions resulting in no detectable cation transport except Na and a small quantity (0.04% to 0.06%) of 137Cs. An average decontamination factor of 2000 was observed with respect to 137Cs. As expected, Gibbsite precipitation was observed as OH- ions were depleted from the tank waste

130

Caustic Recycle from Hanford Tank Waste Using NaSICON Ceramic Membranes  

Energy Technology Data Exchange (ETDEWEB)

A sodium (Na) Super Ion Conductor (NaSICON), has been studied at Pacific Northwest National Laboratory (PNNL) to investigate their ability to separate sodium from radioactively contaminated sodium salt solutions for treating U.S. Department of Energy (DOE) tank wastes. Ceramatec Inc. developed and fabricated a membrane disk containing a proprietary NAS-GY material formulation that was electrochemically tested in a bench-scale apparatus with both a simulant and a radioactive tank-waste solution to determine the membrane performance when removing sodium from DOE tank wastes. Implementing this sodium separation process can result in significant cost savings by reducing the disposal volume of low-activity wastes and by producing a 19M NaOH feedstock product for recycle into waste treatment processes such as sludge leaching, regenerating ion exchange resins, inhibiting corrosion in carbon-steel tanks, or retrieving tank wastes. In actual waste tests, average sodium transport rates of 10.3 kg/day/m2 were achieved at average sodium transport efficiencies of 99%. The membrane was found to be highly selective to sodium ions resulting in no detectable cation transport except Na and a small quantity (0.04% to 0.06%) of 137Cs. An average decontamination factor of 2000 was observed with respect to 137Cs. As expected, Gibbsite precipitation was observed as OH- ions were depleted from the tank waste.

Fountain, Matthew S.; Kurath, Dean E.; Sevigny, Gary J.; Poloski, Adam P.; Pendleton, J.; Balagopal, S.; Quist, M.; Clay, D.

2008-07-15

131

Core structure of a BWR type reactor  

International Nuclear Information System (INIS)

Object: To prevent a control rod inserted space from being blocked by a fuel assembly due to vibrations resulting from earthquake or the like. Structure: A fuel assembly, which comprises upper and lower tie plates and fuel rods and has no channel, is inserted into a fuel assembly inserting space of a cylindrical member interiorly divided by a partition plate into the fuel assembly inserting space and a control rod inserting passage, the cylindrical member having its upper portion retained by a lattice plate and a lower portion thereof supported by a lattic plate or a fuel support. (Furukawa, Y.)

132

Stochastic Fatigue Analysis of Jacket Type Offshore Structures  

DEFF Research Database (Denmark)

In this paper, a stochastic reliability assessment for jacket type offshore structures subjected to wave loads in deep water environments is outlined. In the reliability assessment, structural and loading uncertainties are taken into account by means of some stochastic variables. To estimate statistical measures of structural stress variations the modal spectral analysis method is applied.

Sigurdsson, Gudfinnur

1988-01-01

133

Prediction of Type A behaviour : a structural equation model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

2009-01-01

134

Type II Cadherin Ectodomain Structures: Implications for Classical Cadherin Specificity  

International Nuclear Information System (INIS)

Type I and II classical cadherins help to determine the adhesive specificities of animal cells. Crystal-structure determination of ectodomain regions from three type II cadherins reveals adhesive dimers formed by exchange of N-terminal ? strands between partner extracellular cadherin-1 (EC1) domains. These interfaces have two conserved tryptophan side chains that anchor each swapped strand, compared with one in type I cadherins, and include large hydrophobic regions unique to type II interfaces. The EC1 domains of type I and type II cadherins appear to encode cell adhesive specificity in vitro. Moreover, perturbation of motor neuron segregation with chimeric cadherins depends on EC1 domain identity, suggesting that this region, which includes the structurally defined adhesive interface, encodes type II cadherin functional specificity in vivo

135

Superconducting phases in samples with perovskite-type structure  

International Nuclear Information System (INIS)

Data, pointing out to the presence of several superconducting phases in multicomponent metal-oxide systems with bismuth are obtained. Genesis is considered and a possibility of systematization of superconducting phases with perovskite-type structure is discussed

136

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)

137

Structural stability and formability of ABO3-type perovskite compounds  

International Nuclear Information System (INIS)

On the basis of the bond-valence model (BVM) and structure-map technology, the structural stability and formability of ABO3-type perovskite compounds were investigated in 376 ABO3-type compounds. A new criterion of structural stability for ABO3-type perovskite compounds has been established by the bond-valence calculated tolerance factors, which are in the range 0.822-1.139. All global instability indices for ABO3-type perovskite compounds are found to be less than 1.2 v.u. (valence units) and increase with a decrease in oxidation state of the B cations (i.e. structural stability in the formation of an ideal cubic perovskite follows the order A+B5+O3-type > A2+B4+O3-type > A3+B3+O3-type). Three new two-dimensional structure maps were constructed based on the ideal A-O and B-O bond distances derived from the BVM. These maps indicate the likelihood of particular perovskite compounds being formed. The present work enables novel perovskite and perovskite-related compounds to be explored by screening all the possible elemental combinations in future crystal engineering. (orig.)

138

NMR investigations of Li(+) ion dynamics in the NASICON ionic conductors [Formula: see text].  

Science.gov (United States)

NMR studies of (7)Li and (31)P nuclei are reported in the 150-900 K temperature range for the [Formula: see text] NASICON compounds with x = 0.8, 0.7, 0.6 and 0.3. Magic angle spinning (MAS mode) experiments were performed at room temperature on the (7)Li and (31)P nuclei. The linewidth and the spin lattice relaxation times of these nuclei are studied versus temperature in the static mode. The spectra recorded in the MAS mode show that the (7)Li ions occupy three chemical sites, the occupation of which being very sensitive to the x values but not sensitive to the coexistence of the two varieties [Formula: see text] and [Formula: see text] observed at room temperature in compounds with x?0.5. On the other hand, the (31)P nucleus MAS spectra are very sensitive to lithium content but also to the variety coexistence. T(1) measurements were performed in a static mode on the (7)Li and (31)P nuclei. In all the compounds, the (7)Li spin lattice relaxation time exhibits two branches with several minima, indicating the complex dynamics for this ion. One of these minima appears in the same temperature range as the minimum of the (31)P nucleus T(1), strongly suggesting a cross-relaxation process between these nuclei. T(1?) measurements on (7)Li (static mode) allow us to show a slow motion different from the one probed by the T(1). The analysis of the T(1?) behaviour with temperature and composition allows us to ascribe the motion probed by this time to the oxygen ion motion which monitors the opening and closing of the lithium pathways. A qualitative interpretation of the (7)Li  T(1) results is done; it takes into account the cross-relaxation phenomena between (31)P and (7)Li and quadrupolar fluctuations. PMID:21825419

Barré, Maud; Emery, Joël; Florian, Pierre; Le Berre, Françoise; Crosnier-Lopez, Marie-Pierre; Fourquet, Jean-Louis

2009-04-29

139

SO{sub 2}-sensing characteristics of NASICON sensors with ZnSnO{sub 3} sensing electrode  

Energy Technology Data Exchange (ETDEWEB)

A compact tubular sensor based on sodium super ionic conductor (NASICON) and ZnSnO{sub 3} sensing electrode was designed for the detection of sulfur dioxide. The NASICON and ZnSnO{sub 3} material were prepared by sol-gel method and were analyzed by the X-ray diffraction (XRD) analysis, respectively. And ZnSnO{sub 3} materials were analyzed by SEM. ZnSnO{sub 3} thick film was prepared to investigate characteristics of sulfur dioxide (SO{sub 2}) at various operating temperatures. The sensor using ZnSnO{sub 3} gave excellent sensing properties to 5-50 ppm SO{sub 2} in air at 360-390 deg. C. The EMF value of the sensor was almost proportional to the logarithm of SO{sub 2} concentration, the sensitivity (slope) was 255 mV/decade at 375 deg. C. It was also seen that the sensor showed a good selectivity to SO{sub 2} against H{sub 2}S, NO{sub 2}, Cl{sub 2}, NO and C{sub 7}H{sub 8}. The sensor had speedy response kinetics to SO{sub 2} too, the 90% response time to 5, 10, 20 and 50 ppm SO{sub 2} 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.

Zhong Tiegang [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)], E-mail: gangtie1984@email.jlu.edu.cn; Quan Baofu [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)], E-mail: Quanbf@mail.jlu.edu.cn; Liang Xishuang [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)], E-mail: xs_liang@email.jlu.edu.cn; Liu Fengmin [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)], E-mail: liufm@mail.jlu.edu.cn; Wang Biao [State Key Laboratory on Integrated Optoelectronics, College of Electronic Science and Engineering, Jilin University, 2699 Qianjin Street, Changchun 130012 (China)], E-mail: quanbf@mail.jlu.edu.cn

2008-06-25

140

Thermodynamics of NASICON (Na 1+ xZr 2Si xP 3- xO 12)  

Science.gov (United States)

It is shown that Hong's NASICON solid solution range is intrinsically stable for T > 600 K. With the help of electrochemical and calorimetric experiments, complete thermochemical information of Na 1+ xZr 2Si xP 3- xO 12 (0 ? x ? 3) compositions has been elucidated, i.e., formation enthalpies, standard entropies, and molar volume (1.5-1000 K). For the purpose of a precise evaluation of the electrochemical values the specific heats of ZrP 2O 7 and Na 2ZrSi 2O 7 have also been determined. A thermodynamic mixture model is constructed showing that the solid solution is entropy stabilized. The energetic interaction has a destabilizing influence. The zero-point entropy and the excess entropy at higher temperatures suggest a partial ordering ( {Si}/{P}) at higher temperatures. A miscibility gap, however, which is predicted for T ? 600 K by the model, could not be found due to the slow kinetics or because of a simultaneous phase transformation. The obtained values clearly show that NASICON is thermodynamically unstable with respect to a reaction with elementary sodium. The instability increases with increasing P content.

Warhus, U.; Maier, J.; Rabenau, A.

1988-01-01

 
 
 
 
141

Prediction of crystal structure type for some equiatomic ternary compounds  

International Nuclear Information System (INIS)

The problem of prediction of phases with a certain type of crystal structure is formulated and the method for restoration of the initial function based on teaching computer to formulate notions is suggested. Efficiency of the suggested approach is shown on the example of prediction of new equiatomic ternary phases with ZrNiAl. TiNiSi and PbFCl structures

142

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

143

Structural studies of rutile-type metal dioxides  

Energy Technology Data Exchange (ETDEWEB)

The structures of the four metal dioxides GeO{sub 2}, SnO{sub 2}, RuO{sub 2} and IrO{sub 2} (germanium, tin, ruthenium and iridium dioxides, respectively) have been redetermined by Rietveld refinement from neutron diffraction powder data. The four dioxides all adopt the rutile-type structure, space group P4{sub 2}/mnm (no. 136), with a = 4.4066 (1), 4.7374 (1), 4.4968 (2) and 4.5051 (3), c = 2.8619 (1), 3.1864 (1), 3.1049 (1) and 3.1586 (2) A, and x = 0.3060 (1), 0.3056 (1), 0.3053 (1) and 0.3077 (3), respectively. These results are compared with those for other metal dioxides that adopt the rutile structure and trends in structural and thermal vibrations for a series of 11 metal dioxides which adopt the rutile-type structure are described. (orig.).

Bolzan, A.A. [Sydney Univ. (Australia). School of Chemistry; Fong, C. [Sydney Univ. (Australia). School of Chemistry; Kennedy, B.J. [Sydney Univ. (Australia). School of Chemistry; Howard, C.J. [Australian Nuclear Science and Technology Organisation, Menai, NSW (Australia). Lucas Heights Research Labs.

1997-06-01

144

Structural studies of rutile-type metal dioxides  

International Nuclear Information System (INIS)

The structures of the four metal dioxides GeO2, SnO2, RuO2 and IrO2 (germanium, tin, ruthenium and iridium dioxides, respectively) have been redetermined by Rietveld refinement from neutron diffraction powder data. The four dioxides all adopt the rutile-type structure, space group P42/mnm (no. 136), with a = 4.4066 (1), 4.7374 (1), 4.4968 (2) and 4.5051 (3), c = 2.8619 (1), 3.1864 (1), 3.1049 (1) and 3.1586 (2) A, and x = 0.3060 (1), 0.3056 (1), 0.3053 (1) and 0.3077 (3), respectively. These results are compared with those for other metal dioxides that adopt the rutile structure and trends in structural and thermal vibrations for a series of 11 metal dioxides which adopt the rutile-type structure are described. (orig.)

145

Structural Similarity of Secretins from Type II and Type III Secretion Systems.  

Science.gov (United States)

Secretins, the outer membrane components of several secretion systems in Gram-negative bacteria, assemble into channels that allow exoproteins to traverse the membrane. The membrane-inserted, multimeric regions of PscC, the Pseudomonas aeruginosa type III secretion system secretin, and PulD, the Klebsiella oxytoca type II secretion system secretin, were purified after cell-free synthesis and their structures analyzed by single particle cryoelectron microscopy. Both homomultimeric, barrel-like structures display a "cup and saucer" architecture. The "saucer" region of both secretins is composed of two distinct rings, with that of PulD being less segmented than that of PscC. Both secretins have a central chamber that is occluded by a plug linked to the chamber walls through hairpin-like structures. Comparisons with published structures from other bacterial systems reveal that secretins have regions of local structural flexibility, probably reflecting their evolved functions in protein secretion and needle assembly. PMID:25156426

Tosi, Tommaso; Estrozi, Leandro F; Job, Viviana; Guilvout, Ingrid; Pugsley, Anthony P; Schoehn, Guy; Dessen, Andréa

2014-09-01

146

Structural fabrication of a ring-type motion sensor  

Science.gov (United States)

The structural fabrication of a ring-type motion sensor is described. This micromachined ring-type sensor can be used to detect both yaw rate and linear acceleration. The fabrication is based on deep silicon etching and wafer bonding. An aspect ratio dependent effect (ARDE) always occurs in the dry etching process for a micro electromechanical systems (MEMS) device. Additionally, three processes are developed and modified progressively for eliminating ARDE from the fabrication results. Results indicate that the proposed process provides more flexibility than other processes with respect to the structural fabrication of a MEMS device. The sensitivity of the sensor characteristic to the manufacturing errors is considered as well.

Weng, Jui-Hong; Chieng, Wei-Hua; Lai, Jenn-Min

2004-05-01

147

Synthesis, crystal structure and spectroscopy properties of Na3 AZr(PO4)3 (A=Mg, Ni) and Li2.6Na0.4NiZr(PO4)3 phosphates  

International Nuclear Information System (INIS)

Na3 AZr(PO4)3 (A=Mg, Ni) phosphates were prepared at 750 deg. C by coprecipitation route. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Li2.6Na0.4NiZr(PO4)3 was synthesized through ion exchange from the sodium analog. These materials belong to the Nasicon-type structure. Raman spectra of Na3 AZr(PO4)3 (A=Mg, Ni) phosphates present broad peaks in favor of the statistical distribution in the sites around PO4 tetrahedra. Diffuse reflectance spectra indicate the presence of octahedrally coordinated Ni2+ ions. - Graphical abstract: Structure of Na3 AZr(PO4)3 (A=Mg, Ni) phosphates. Display Omitted

148

Prediction of Type A behaviour: a structural equation model  

Scientific Electronic Library Online (English)

Full Text Available SciELO South Africa | Language: English Abstract in english 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.

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

149

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

150

Extended radio structure of BL Lac type objects  

International Nuclear Information System (INIS)

The results are reported of an investigation of the arc-second radio structure of a sample of 11 BL Lac type objects which show that they possess the general core-halo morphology predicted by the so-called Blazer models although compact jet-like features are much less conspicuous in these objects than in quasars. (U.K.)

151

Optimization of structure of multicell-type transistor converter  

Directory of Open Access Journals (Sweden)

Full Text Available To optimize the structure of multicell-type transistor converter with combined control it is proposed to use an additive criterion, wich would take into account such particular criteria as efficiency, cost and construction volume of the converter.

Bondarenko Yu. V.

2012-02-01

152

Prediction of type A behaviour: A structural equation model  

Directory of Open Access Journals (Sweden)

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.

How to cite this article:

Van Wyk, R., Boshoff, A.B., Nieman, G., Van Vuuren, J., & Pretorius, M. (2009. Prediction of type A behaviour: A structural equation model. SA Journal of Industrial Psychology/SA Tydskrif vir Bedryfsielkunde, 35(1, Art. #758, 9 pages. DOI: 10.4102/sajip.v35i1.758

Marius Pretorius

2009-04-01

153

A Quasi-Type-1 Phase-Locked Loop Structure  

DEFF Research Database (Denmark)

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.

Golestan, Saeed; Fernandez, Francisco Daniel Freijedo

2014-01-01

154

Insertion of Li, Na, K, Rb, and Cs in the unfilled structure of Nb2(PO4)3  

International Nuclear Information System (INIS)

For studying intercalation of alkali metal ions (M = Li-Cs) into niobium (4, 5) orthophosphate of the composition Nb2(PO4)3 (1) a method was developed for synthesizing orthophosphates of the series MxNb1+x4+Nb1-x5+ (PO4)3 (2) and matrix of 1 from open systems of condensed phosphorus acids. The compounds prepared were characterized by data of chemical, thermal and X-ray phase analyses, as well as by IR spectroscopy. It was ascertained that both matrix of 1 and the entire series of interstitial solid solutions of 2 belong to the NASICON structural type. Introduction of alkali metal, irrespective of its radius and polarizing ability, promotes stabilization of niobium (4) oxidation state and formation of substituted orthophosphates of 2 of a fixed composition

155

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

156

Synthesis, crystal structure and spectroscopy properties of Na 3AZr(PO 4) 3 ( A=Mg, Ni) and Li 2.6Na 0.4NiZr(PO 4) 3 phosphates  

Science.gov (United States)

Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates were prepared at 750 °C by coprecipitation route. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Li 2.6Na 0.4NiZr(PO 4) 3 was synthesized through ion exchange from the sodium analog. These materials belong to the Nasicon-type structure. Raman spectra of Na 3AZr(PO 4) 3 ( A=Mg, Ni) phosphates present broad peaks in favor of the statistical distribution in the sites around PO 4 tetrahedra. Diffuse reflectance spectra indicate the presence of octahedrally coordinated Ni 2+ ions.

Chakir, M.; El Jazouli, A.; de Waal, D.

2006-06-01

157

Structure, stability and electronic properties of tricycle type graphane  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We propose a new allotrope of graphane, named as tricycle graphane,with a 4up/2down UUUDUD hydrogenation in each hexagonal carbon ring,which is different from previously proposed allotropes with UUDUUD(boat-1) and UUUUDD (boat-2) types of hydrogenation. Its stability and electronic structures are systematically studied using first-principles method. We find that the tricycle graphane is a stable phase in between the previously proposed chair and stirrup allotropes. Its elect...

He, Chaoyu; Sun, L. Z.; Zhang, C. X.; Jiao, N.; Zhang, K. W.; Zhong, Jianxin

2012-01-01

158

Star cell type core configuration for structural sandwich materials  

Science.gov (United States)

A new pattern for cellular core material used in sandwich type structural materials is disclosed. The new pattern involves star shaped cells intermixed with hexagonal shaped cells. The new patterned cellular core material includes star shaped cells interconnected at points thereof and having hexagonal shape cells positioned adjacent the star points. The new pattern allows more flexibility and can conform more easily to curved shapes. 3 figs.

Christensen, R.M.

1995-08-01

159

The Three-Dimensional Structural Basis of Type II Hyperprolinemia  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2012-08-31

160

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

 
 
 
 
161

?????????????????? Calculation of Interplanar Spacing and Structure-Factor of Diamond-Type Structure  

Directory of Open Access Journals (Sweden)

Full Text Available ??????“????S”???????????????????????????????????????????????????????????????????????????With the “site-factor S” of an addition atom, the possible four kinds of interplanar spacing of diamond-type structure was calculated. In addition, the structure-factor of this structure was calculated, and a correlativity between the interplanar spacing and the structure-factor was analysed. Finally, a difference in missing reflection conditions between diamond-type structure and face-centered cubic structure was discussed.

???

2012-07-01

162

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

163

Structure and mechanism of Escherichia coli type I signal peptidase.  

Science.gov (United States)

Type I signal peptidase is the enzyme responsible for cleaving off the amino-terminal signal peptide from proteins that are secreted across the bacterial cytoplasmic membrane. It is an essential membrane bound enzyme whose serine/lysine catalytic dyad resides on the exo-cytoplasmic surface of the bacterial membrane. This review discusses the progress that has been made in the structural and mechanistic characterization of Escherichia coli type I signal peptidase (SPase I) as well as efforts to develop a novel class of antibiotics based on SPase I inhibition. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. PMID:24333859

Paetzel, Mark

2014-08-01

164

New germanide superconductors with the type-I clathrate type structure  

International Nuclear Information System (INIS)

Highlights: •We discovered that the new germanide superconductors of A8(Al,Ge)46 (A = Rb, Cs). •The superconducting transition temperature is confirmed at around 3.6 K for A = Rb and 4 K for A = Cs. •The M–H curve at 1.8 K shows that the Rb8(Al,Ge)46 belongs to a type-II superconductor. -- Abstract: We discovered that the new germanide superconductors of A8(Al,Ge)46 (A = Rb, Cs). A8(Al,Ge)46 have the type-I clathrate type structure (cubic, space group: Pm3¯n (No. 223)). The superconducting transition temperature is confirmed at around 3.6 K for Rb8(Al0.4Ge0.6)46 and 4 K for Cs8(Al0.4Ge0.6)46, respectively. The lattice constants of these compounds are estimated to be a = 1.082(6) nm for Rb8(Al0.4Ge0.6)46 and a = 1.087(8) nm for Cs8(Al0.4Ge0.6)46. The M–H curve at 1.8 K shows that the Rb8(Al0.4Ge0.6)46 is categorized to be a conventional type-II superconductor. The superconducting parameters of Rb8(Al0.4Ge0.6)46 are determined using the thermodynamic data and Ginzburg–Landau relations

165

The Importance of Disk Structure in Stalling Type I Migration  

CERN Document Server

As planets form they tidally interact with their natal disks. Though the tidal perturbation induced by Earth and super-Earth mass planets is generally too weak to significantly modify the structure of the disk, the interaction is potentially strong enough to cause the planets to undergo rapid type I migration. This physical process may provide a source of short-period super-Earths, though it may also pose a challenge to the emergence and retention of cores on long-period orbits with sufficient mass to evolve into gas giants. Previous numerical simulations have shown that the type I migration rate sensitively depends upon the circumstellar disk's properties, particularly the temperature and surface density gradients. Here, we derive these structure parameters for 1) a self-consistent viscous-disk model based on a constant \\alpha-prescription, 2) an irradiated disk model that takes into account heating due to the absorption of stellar photons, and 3) a layered-accretion disk model with variable \\alpha-parameter...

Kretke, Katherine A

2012-01-01

166

THE IMPORTANCE OF DISK STRUCTURE IN STALLING TYPE I MIGRATION  

Energy Technology Data Exchange (ETDEWEB)

As planets form they tidally interact with their natal disks. Though the tidal perturbation induced by Earth and super-Earth mass planets is generally too weak to significantly modify the structure of the disk, the interaction is potentially strong enough to cause the planets to undergo rapid type I migration. This physical process may provide a source of short-period super-Earths, though it may also pose a challenge to the emergence and retention of cores on long-period orbits with sufficient mass to evolve into gas giants. Previous numerical simulations have shown that the type I migration rate sensitively depends upon the circumstellar disk's properties, particularly the temperature and surface density gradients. Here, we derive these structure parameters for (1) a self-consistent viscous-disk model based on a constant {alpha} prescription, (2) an irradiated disk model that takes into account heating due to the absorption of stellar photons, and (3) a layered accretion disk model with variable {alpha} parameter. We show that in the inner viscously heated regions of typical protostellar disks, the horseshoe and corotation torques of super-Earths can exceed their differential Lindblad torque and cause them to undergo outward migration. However, the temperature profile due to passive stellar irradiation causes type I migration to be inward throughout much of the disk. For disks in which there is outward migration, we show that location and the mass range of the 'planet traps' depend on some uncertain assumptions adopted for these disk models. Competing physical effects may lead to dispersion in super-Earths' mass-period distribution.

Kretke, Katherine A. [Southwest Research Institute, Boulder, CO 80302 (United States); Lin, D. N. C., E-mail: kretke@boulder.swri.edu [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States)

2012-08-10

167

Synthesis of nano structured particles for Li-ion cathodic and anodic materials obtained by spray pyrolysis; Sintesis de particulas nanoestructuradas para materiales catodicos y anodicos obtenidos mediante Spray Prolisis  

Energy Technology Data Exchange (ETDEWEB)

The development of the nano technology has contributed to improve the electrochemical properties in rechargeable batteries. The Spray Pyrolysis method allows to obtain nano structured materials with spherical morphology, narrow particle size distribution and compositional homogeneity. Nano structured particles have been prepared in this work to be used as anodic and cathodic materials in lithium-ion batteries. Among the cathodic materials, the Na-Si-Con (Li{sub 3}Fe{sub 2}(PO{sub 4}){sub 3}) structure and the olivine (LiFePO{sub 4}) phases have been synthesised. The Na-Si-Con iron phosphate favours the accommodation of the ion host, the diffusion and thermal stability. The olivine structure has an open three-dimensional network, favourable for hosting Lithium ions. The characterization by X ray diffraction, electron microscopy (scanning and transmission) and electron diffraction have allowed to identify a mix of crystalline phases of LiFePO{sub 4} (Olivine) and Li{sub 3}Fe{sub 2}(PO{sub 4}){sub 3} (Na-Si-Con). Thermal treatments produce porous particles. The tryphilite phase (olivine) appears after a thermal treatment at 800 degree centigrade/12h. Electrochemical results confirm the presence of the Na-Si-Con and olivine phases. Among the materials for being used as anode, the titanium oxides have been classified as good candidates as lithium ion host. The synthesis results in different experimental conditions for obtaining spherical and nano structured titanium oxide particles are presented. (Author)

Gomez, L. S.; Meatza, I. de; Martin, M. I.; Boynao, I.; Cantero, I.; Rabanal, M. E.

2010-07-01

168

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.

169

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

170

Gradient type optimization methods for electronic structure calculations  

CERN Document Server

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...

Zhang, Xin; Wen, Zaiwen; Zhou, Aihui

2013-01-01

171

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)

172

Magnetic resonances in perovskite-type layer structures  

International Nuclear Information System (INIS)

We have studied the q = 0 magnetic excitations of the perovskite-type layer structures A2MnCl4 with A = Rb, Csub(n)Hsub(2n+1)NH3 (n = 1,2,3), and NH3(CH2)sub(m)NH3MnCl4 (m = 2,4,5) in the antiferromagnetic and in the spin flop regime by means of magnetic resonance in the mm-wave range (30-130 GHz) and microwave range (9.2 GHz). The length of the organic molecules determines the separation of the MnCl6 octahedra. With increasing separation the Neel temperature and the antiferromagnetic resonance frequency decrease, which mainly originates from a decrease of the anisotropy field. (orig.)

173

Mechanism and structure of the bacterial type IV secretion systems.  

Science.gov (United States)

The bacterial type IV secretion systems (T4SSs) translocate DNA and protein substrates to bacterial or eukaryotic target cells generally by a mechanism dependent on direct cell-to-cell contact. The T4SSs encompass two large subfamilies, the conjugation systems and the effector translocators. The conjugation systems mediate interbacterial DNA transfer and are responsible for the rapid dissemination of antibiotic resistance genes and virulence determinants in clinical settings. The effector translocators are used by many Gram-negative bacterial pathogens for delivery of potentially hundreds of virulence proteins to eukaryotic cells for modulation of different physiological processes during infection. Recently, there has been considerable progress in defining the structures of T4SS machine subunits and large machine subassemblies. Additionally, the nature of substrate translocation sequences and the contributions of accessory proteins to substrate docking with the translocation channel have been elucidated. A DNA translocation route through the Agrobacterium tumefaciens VirB/VirD4 system was defined, and both intracellular (DNA ligand, ATP energy) and extracellular (phage binding) signals were shown to activate type IV-dependent translocation. Finally, phylogenetic studies have shed light on the evolution and distribution of T4SSs, and complementary structure-function studies of diverse systems have identified adaptations tailored for novel functions in pathogenic settings. This review summarizes the recent progress in our understanding of the architecture and mechanism of action of these fascinating machines, with emphasis on the 'archetypal' A. tumefaciens VirB/VirD4 T4SS and related conjugation systems. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey. PMID:24389247

Christie, Peter J; Whitaker, Neal; González-Rivera, Christian

2014-08-01

174

New germanide superconductors with the type-I clathrate type structure  

Energy Technology Data Exchange (ETDEWEB)

Highlights: •We discovered that the new germanide superconductors of A{sub 8}(Al,Ge){sub 46} (A = Rb, Cs). •The superconducting transition temperature is confirmed at around 3.6 K for A = Rb and 4 K for A = Cs. •The M–H curve at 1.8 K shows that the Rb{sub 8}(Al,Ge){sub 46} belongs to a type-II superconductor. -- Abstract: We discovered that the new germanide superconductors of A{sub 8}(Al,Ge){sub 46} (A = Rb, Cs). A{sub 8}(Al,Ge){sub 46} have the type-I clathrate type structure (cubic, space group: Pm3{sup ¯}n (No. 223)). The superconducting transition temperature is confirmed at around 3.6 K for Rb{sub 8}(Al{sub 0.4}Ge{sub 0.6}){sub 46} and 4 K for Cs{sub 8}(Al{sub 0.4}Ge{sub 0.6}){sub 46}, respectively. The lattice constants of these compounds are estimated to be a = 1.082(6) nm for Rb{sub 8}(Al{sub 0.4}Ge{sub 0.6}){sub 46} and a = 1.087(8) nm for Cs{sub 8}(Al{sub 0.4}Ge{sub 0.6}){sub 46}. The M–H curve at 1.8 K shows that the Rb{sub 8}(Al{sub 0.4}Ge{sub 0.6}){sub 46} is categorized to be a conventional type-II superconductor. The superconducting parameters of Rb{sub 8}(Al{sub 0.4}Ge{sub 0.6}){sub 46} are determined using the thermodynamic data and Ginzburg–Landau relations.

Ipponjima, T., E-mail: ipponjima@phys.aoyama.ac.jp [Department of Physics and Mathematics, Aoyama-Gakuin University, 5-10-1 Fuchinobe, Sagamihara-shi, Kanagawa 252-5258 (Japan); Kawashima, K.; Miyazaki, S.; Hyakumura, D. [Department of Physics and Mathematics, Aoyama-Gakuin University, 5-10-1 Fuchinobe, Sagamihara-shi, Kanagawa 252-5258 (Japan); Yoshikawa, M. [IMRA Material Co. Ltd., 2-1 Asahicho, Kariya, Aichi 448-0032 (Japan); Akimitsu, J. [Department of Physics and Mathematics, Aoyama-Gakuin University, 5-10-1 Fuchinobe, Sagamihara-shi, Kanagawa 252-5258 (Japan)

2013-11-15

175

Structural investigations on native collagen type I fibrils using AFM  

International Nuclear Information System (INIS)

This study was carried out to determine the elastic properties of single collagen type I fibrils with the use of atomic force microscopy (AFM). Native collagen fibrils were formed by self-assembly in vitro characterized with the AFM. To confirm the inner assembly of the collagen fibrils, the AFM was used as a microdissection tool. Native collagen type I fibrils were dissected and the inner core uncovered. To determine the elastic properties of collagen fibrils the tip of the AFM was used as a nanoindentor by recording force-displacement curves. Measurements were done on the outer shell and in the core of the fibril. The structural investigations revealed the banding of the shell also in the core of native collagen fibrils. Nanoindentation experiments showed the same Young's modulus on the shell as well as in the core of the investigated native collagen fibrils. In addition, the measurements indicate a higher adhesion in the core of the collagen fibrils compared to the shell

176

Type IIA orientifolds on SU(2)-structure manifolds  

Energy Technology Data Exchange (ETDEWEB)

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.)

Danckaert, Thomas

2010-11-15

177

Structural health monitoring of PC structures with novel types of distributed sensors  

Science.gov (United States)

In this paper, the structural health monitoring of a pre-stressed concrete (PC) structure based on two types of distributed sensing techniques is addressed. The sensing elements are Brillouin scattering-based fiber optic sensors (FOSs) and HCFRP (hybrid carbon fiber reinforced polymer) sensors composed of three types of carbon tows. Both types of sensors are characterized by a broad-based and distributed sensing function. The HCFRP sensors are bonded on PC tendon, steel reinforcing bar, and embedded in tensile and compressive concrete sides with epoxy resins and putties. The FOSs are embedded in the tensile and compressive concrete sides where the HCFRP sensors are embedded as well. The distributed sensors are arranged to detect and monitor the initiation and propagation of cracks, yielding of steel reinforcements and corrosion of PC tendons. The experimental investigations demonstrate that the initiation and location of cracks, yielding of steel reinforcements, corrosion of PC tendons and structural health of PC structures can be effectively detected and monitored with such kinds of distributed sensing systems.

Yang, Caiqian; Wu, Zhishen; Zhang, Yufeng

2010-04-01

178

29Si and 31P MAS NMR study of the Nasicon system na 1+?Zr 2(SiO 4) ?(PO 4) 3-?  

Science.gov (United States)

The original NASICON system Na 1+?Zr 2(SiO 4) ?(PO 4) 3-? was investigated by 29Si and 31P NMR. With increasing ? a continuous down-field shift of the single resonance lines was observed both in 29Si and 31P NMR. The linewidth shows a maximum around ? = 1.5. Both effects are explained by a change in the net atomic charge qZr of zirconium caused by the substitution of phosphorus by silicon. In Na 4Zr 2(SiO 4) 3qZr was estimated to be 1.32 from the NMR data.

Jäger, C.; Scheler, G.; Sternberg, U.; Barth, S.; Feltz, A.

1988-05-01

179

Structural trends in off stoichiometric chalcopyrite type compound semiconductors  

Energy Technology Data Exchange (ETDEWEB)

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.

Stephan, Christiane

2011-03-15

180

GOES-R User Data Types and Structure  

Science.gov (United States)

GOES-R meteorological data is provided to the operational and science user community through four main distribution mechanisms. The GOES-R Ground Segment (GS) generates a set of Level 1b (L1b) data from each of the six primary satellite instruments and formats the data into a direct broadcast stream known as GOES Rebroadcast (GRB). Terrestrially, cloud and moisture imagery data is provided to forecasters at the National Weather Service (NWS) through a direct interface to the Advanced Weather Interactive Processing System (AWIPS). A secondary pathway for the user community to receive data terrestrially is via NOAA's Environmental Satellite Processing and Distribution System (ESPDS) Product Distribution and Access (PDA) system. The ESPDS PDA will service the NWS and other meteorological users through a data portal, which provides both a subscription service and an ad hoc query capability. Finally, GOES-R data is made available to NOAA's Comprehensive Large Array-Data Stewardship System (CLASS) for long-term archive. CLASS data includes the L1b and L2+ products sent to PDA, along with the Level 0 data used to create these products, and other data used for product generation and processing. This session will provide a summary description of the data types and formats associated with each of the four primary distribution pathways for user data from GOES-R. It will discuss the resources that are being developed by GOES-R to document the data structures and formats. It will also provide a brief introduction to the types of metadata associated with each of the primary data flows.

Royle, A. W.

2012-12-01

 
 
 
 
181

Crystal structure, electronic structure and thermoelectric properties of n-type BiSbSTe2  

International Nuclear Information System (INIS)

N-type bismuth telluride sulfide has received attention as a potential thermoelectric material due to its large thermopower and ability to form solid solutions with bismuth antimony sulfide. Here, we fabricated an n-type tetradymite BiSbSTe2 by solid-state reaction. The crystal structure was found to be rhombohedral, and the thermoelectric properties were measured for the temperature range 50-390 K. A high Seebeck coefficient of -190 µV K-1 was achieved at 385 K. The electronic structure of BiSbSTe2 was investigated using first-principles calculations and compared with its parent counterpart (Bi2STe2). The results have shown that BiSbSTe2 is a narrow band-gap semiconductor. For the first time, we have demonstrated that the vacancies in substitutional atomic sites, which can be altered through different fabrication techniques, can determine the charge carrier nature of tetradymite thermoelectrics. As a proof of concept, we have shown that the vacancies in antimony sites result in a p-type compound while a sulfur deficiency produces an n-type phase with lower electrical conductivity. (paper)

182

Structure, Stoichiometry and Stability in Magnetoplumbite and {beta}-Alumina Structured Type Ceramics. Final Report  

Energy Technology Data Exchange (ETDEWEB)

Work has been completed on the atomistic simulation of hexa-aluminate ceramics with the magnetoplumbite and beta-alumina type structures. In this report, three aspects of the work are highlighted. One is the simulation of surface structures. The second concerns details of the interstitially mechanisms observed in molecular dynamics simulations. The novel result here is the observation that the lattice ion always leaves its Beevers-Ross site before the aBR interstitial begins to move towards the lattice site. It is also found that, as expected, the interstitial mechanism is the most common mechanism in the heavily disordered nonstoichiometric structure, as well as in the stoichiometric material. Finally, the disposition of trivalent europium in the phosphor material BAM has been elucidated.

Cormack, A. N.

2004-03-01

183

The influence of the type of road, the type of vehicle and the age structure on the road transport emission  

Directory of Open Access Journals (Sweden)

Full Text Available The total emission level is heavily dependent on the number of vehicles. Additionally, the type of vehicles and their age structures are very important. The structure of vehicles also depends on the type of the road. The article presents the results of calculations of the pollutants emission from the road transport. Total emission was calculated with combination of the investigation results i.e. the type of vehicles and their age structures for different types of roads. The investigations have been made for different classes of roads with different types of vehicles. The traffic line has been recorded in the same length of time. On the basis of analysis of the recorded traffic line, the number and the type of vehicles have been estimated. The classification of vehicles have been made according to the level of emission i.e. passenger cars, light duty vehicles, heavy duty vehicles, busses and others, taking into consideration the age structures of vehicles. The level of total traffic emission has been calculated on the basis of results. There has been used the Copert programme methodology. The results of the calculations have been made with combination of the type of road, the speed of vehicles, the type of vehicles and their age structure, are presented.

Aleksandra KUTRZYK

2010-01-01

184

Study on lithium/air secondary batteries - Stability of NASICON-type lithium ion conducting glass-ceramics with water  

Energy Technology Data Exchange (ETDEWEB)

The water stability of the fast lithium ion conducting glass-ceramic electrolyte, Li{sub 1+x+y}Al{sub x}Ti{sub 2-x}Si{sub y}P{sub 3-y}O{sub 12} (LATP), has been examined in distilled water, and aqueous solutions of LiNO{sub 3}, LiCl, LiOH, and HCl. This glass-ceramics are stable in aqueous LiNO{sub 3} and aqueous LiCl, and unstable in aqueous 0.1 M HCl and 1 M LiOH. In distilled water, the electrical conductivity slightly increases as a function of immersion time in water. The Li-Al/Li{sub 3-x}PO{sub 4-y}N{sub y}/LATP/aqueous 1 M LiCl/Pt cell, where lithium phosphors oxynitrides Li{sub 3-x}PO{sub 4-y}N{sub y} (LiPON) are used to protect the direct reaction of Li and LATP, shows a stable open circuit voltage (OCV) of 3.64 V at 25 C, and no cell resistance change for 1 week. Lithium phosphors oxynitride is effectively used as a protective layer to suppress the reaction between the LATP and Li metal. The water-stable Li/LiPON/LATP system can be used in Li/air secondary batteries with the air electrode containing water. (author)

Hasegawa, Satoshi; Imanishi, Nobuyuki; Zhang, Tao; Xie, Jian; Hirano, Atsushi; Takeda, Yasuo; Yamamoto, Osamu [Department of Chemistry, Faculty of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507 (Japan)

2009-04-01

185

Electrochemical properties of Li symmetric solid-state cell with NASICON-type solid electrolyte and electrodes  

Energy Technology Data Exchange (ETDEWEB)

All-solid-state phosphate symmetric cells using Li{sub 3}V{sub 2}(PO{sub 4}){sub 3} for both the positive and negative electrodes with the phosphate Li{sub 1.5}Al{sub 0.5}Ge{sub 1.5}(PO{sub 4}){sub 3} as the solid electrolyte were proposed. Amorphous Li{sub 1.5}Al{sub 0.5}Ge{sub 1.5}(PO{sub 4}){sub 3} was added into the electrode to increase the interface area between the active materials and the electrolyte. Any other phases were not formed at the electrode/electrolyte interface even after hot pressing at 600 C. The discharge capacity was 92 mAh g{sup -} {sup 1} at 22 {mu}A cm{sup -} {sup 2} at 80 C, and 38 mAh g{sup -} {sup 1} at 25 C, respectively. Symmetric cell configuration leads to simplify the fabrication process for all-solid-state batteries and will reduce manufacturing costs. (author)

Kobayashi, Eiji; Plashnitsa, Larisa S.; Doi, Takayuki; Okada, Shigeto; Yamaki, Jun-ichi [Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga Koen 6-1, Kasuga-shi, Fukuoka 816-8580 (Japan)

2010-07-15

186

Seismic verification methods for structures and equipment of VVER-type and RBMK-type NPPs (summary of experiences)  

International Nuclear Information System (INIS)

The main verification methods for structures and equipment of already existing VVER-type and RBMK-type NPPs are briefly described. The following aspects are discussed: fundamental seismic safety assessment principles for VVER/RBMK-type NPPs (seismic safety assessment procedure, typical work plan for seismic safety assessment of existing NPPs, SMA (HCLPF) calculations, modified GIP (GIP-VVER) procedure, similarity of VVER/RBMK equipment to that included in the SQUG databases and seismic interactions

187

Structural investigation of Eu 2+ emissions from alkaline earth zirconium phosphate  

Science.gov (United States)

Eu 2+ doped A0.5Zr 2(PO 4) 3 ( A=Ca, Sr, Ba) phosphors with the NASICON structure were synthesized by a co-precipitation method. Their photoluminescent and structural properties were investigated by photoluminescent spectroscopy and powder X-ray Rietveld analysis, which determined two sites for Eu 2+ ions in the host structure, 3 a and 3 b. The Eu-O bond lengths were increased by changing alkaline earth ions from Ca to Ba, causing Eu 2+ emission bands to shift from blue-green to blue. A correlation was observed between the peak wavelength positions and the Eu-O bond length. The photoluminescent properties are discussed in terms of crystal field strength and nephelauxetic effect, and a schematic diagram of Eu 2+ emissions is proposed for the Eu 2+ doped NASICON phosphor.

Hirayama, Masaaki; Sonoyama, Noriyuki; Yamada, Atsuo; Kanno, Ryoji

2009-04-01

188

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

189

Synthesis and crystal structure of CuZrTiO5-A new crystal structure type  

International Nuclear Information System (INIS)

A new compound, CuZrTiO5, was synthesized as strongly pleochroic green crystals from the oxides between 995 and 1010 deg. C, 1 atm. Its crystal structure was determined by single crystal XRD, resulting in R (F2>2?(F2))=0.032 and wR (all data)=0.079). CuZrTiO5 is orthorhombic, space group P212121, a=3.5871(3) A, b=6.6968(4) A, c=14.6679(9) A, V=352.35(4) A3, Z=4. The structure is topologically similar to In2TiO5 but differs in space group and cation coordination. CuZrTiO5 has relatively regular TiO6 polyhedra, but coordination is 7+1 for Zr, and 4+2 for Cu due to the Jahn-Teller effect. Ordering of the long Cu-O bonds causes reduction in symmetry relative to In2TiO5. Layers of Cu alternate with Ti+Zr on (001), giving rise to a distinct cleavage. Bond valence sums on Ti and Zr are far from ideal, which appears due to the limited ability of this structural topology to avoid close next-nearest neighbour distances. - Graphical abstract: The new compound CuZrTiO5 is orthorhombic (P212121), with a=3.5871(3) A, b=6.6968(4) A, c=14.6679(9) A. The structure, determined with single crystal XRD, represents a new crystal structure type that is a slight distortion of that of In2TiO5 but differs in space group and cation coordination.

190

A New Type of Center Data Structure in Cloud Computing  

Directory of Open Access Journals (Sweden)

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.

Guo Xiaohui

2014-01-01

191

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

192

Well-formedness and typing rules for UML Composite Structures  

CERN Document Server

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.

Dragomir, Iulia

2010-01-01

193

Vortex-type elastic structured media and dynamic shielding  

CERN Document Server

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.

Brun, Michele; Movchan, Alexander B

2012-01-01

194

Structural investigation of Eu2+ emissions from alkaline earth zirconium phosphate  

International Nuclear Information System (INIS)

Eu2+ doped A0.5Zr2(PO4)3 (A=Ca, Sr, Ba) phosphors with the NASICON structure were synthesized by a co-precipitation method. Their photoluminescent and structural properties were investigated by photoluminescent spectroscopy and powder X-ray Rietveld analysis, which determined two sites for Eu2+ ions in the host structure, 3a and 3b. The Eu-O bond lengths were increased by changing alkaline earth ions from Ca to Ba, causing Eu2+ emission bands to shift from blue-green to blue. A correlation was observed between the peak wavelength positions and the Eu-O bond length. The photoluminescent properties are discussed in terms of crystal field strength and nephelauxetic effect, and a schematic diagram of Eu2+ emissions is proposed for the Eu2+ doped NASICON phosphor. - Graphical abstract: Eu2+ doped NASICON structured A0.5Zr2(PO4)3 (A=Ca, Sr, Ba) showed the blue and blue-green colored emissions attributed to 4f65d1-4f7 transitions. The photoluminescent properties are discussed in terms of crystal field strength and nephelauxetic effect using powder X-ray Rietveld analysis.

195

On the structures of magnetic flux rope type  

International Nuclear Information System (INIS)

The analysis of observation results of structures like magnetic flux ropes in the magnetotail carried out by the satellite Prognoz-9 is presented. The rope magnetic perturbation data are compared to the magnetic field characteristics in the interplanetary medium and near the bow shock wave front. 4 refs.; 4 figs

196

Antigenic structure of chimeras of type 1 and type 3 polioviruses involving antigenic sites 2, 3 and 4.  

Science.gov (United States)

Chimeric polioviruses have been made in which regions of the type 1 Sabin strain corresponding to antigenic sites 2, 3 and 4 have been replaced by the corresponding regions of the type 3 Sabin strain. Manipulation of one site or a component of it generally did not affect the reactions of the others, suggesting that they form independent structural features. The extent to which the inserted site expressed the antigenic properties of type 3 could be assessed by reaction with polyclonal or monoclonal antibodies, or by immunogenicity. Site 2 could be expressed on infectious virus and site 3 on heated non-infectious virus (C antigen), but not on the native virion. The results are consistent with the view that sites consisting of a continuous sequence of amino acids may be presented on chimeras, whereas more complex sites, such as site 4 or site 3 of the native virion, are transferred less readily from type 3 to type 1. PMID:1717641

Minor, P D; Ferguson, M; Katrak, K; Wood, D; John, A; Howlett, J; Dunn, G; Burke, K; Almond, J W

1991-10-01

197

Structures in the fundamental plane of early-type galaxies  

CERN Document Server

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...

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

2010-01-01

198

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

199

Stress analysis of top hat type structure for random loading  

International Nuclear Information System (INIS)

To resolve several arguments raised for the current analysis of a structure like top hat, which is composed of flange, cylinder and plate, the dynamic response analysis is performed for the full and half models. The dynamic characteristics are investigated for full and half models and the results are compared between them. The response such as bolt reactions and stresses due to random loading are also obtained using the analysis capabilities between commercial programs which have the routine for the random vibration analysis. Several general purpose structural analysis programs are used to get the response due to the random loadings. Also the application of the random loading and the effect of correlations such as fully correlated, partially correlated and fully uncorrelated cases are studied and the general directions for the generation of design loads due to random loading are suggested. (author)

200

The structure of electric disk-type generators  

International Nuclear Information System (INIS)

The constructions of multilayer disk electric generators with compact dimensional packing of magnetic and current layers are considered. The structures of topological generators, namely superconductor generators, high-voltage capacitance generators, and inductive generators with electromagnetic or permanent magnet excitation are discussed. The main operating principles of multilayer generators and geometry dependence are described. The proposed design solutions appear suitable for the use in autonomous power electric systems as well as for the applications requiring the minimum mass and overall dimensions

 
 
 
 
201

Electron density - structure relationships in some perovskite-type compounds  

International Nuclear Information System (INIS)

Experimentally measured electron-deformation densities for the structurally related compounds dipotassium palladium tetrachloride, K2PdCl4, dipotassium silicon hexafluoride, K2SiF6, dipotassium palladium hexachloride, K2PdCl6, and dipotassium nickel tetrafluoride, K2NiF4, contain significant features in interatomic regions. The topographical relationship of interatom depletions to the structural geometry indicates that they originate from non-bonded interactions between atoms. The ?? maps for K2PdCl4 and K2PdCl6 show unexpected structure near the K atoms. Low-temperature studies on K2SiF6 and K2PdCl4 indicate that these features are not due to anharmonic thermal motion, in marked contrast to those near the halide atoms. For the new low-temperature analysis included in the study: K2SiF6, cubic, Fm anti 3m, Mr = 220.27, a = 8.046 (2) A, V = 520.9 (4) A3, Z = 4, Dx = 2.81 (2) Mg m-3, ?(Mo K?) = 2.09 mm-1, F(000) = 424, T = 110 K, R = 0.070, wR = 0.024, S = 1.47 (9) for 129 independent reflections. (orig.)

202

Crystal structure of zebrafish Interferons 1 and 2 reveals a conservation of type I Interferon structure in vertebrates  

DEFF Research Database (Denmark)

Interferons (IFNs) play a major role in orchestrating the innate immune response towards viruses in vertebrates, and their defining characteristic is their ability to induce an antiviral state in responsive cells. Interferons have been described in a multitude of species, from bony fish to mammals. However, our current knowledge about the molecular function of fish IFNs as well as their evolutionary relationship to tetrapod IFNs is limited. Here we establish the 3D structure of zebrafish IFN1 and IFN2 by crystallography. These high-resolution structures offer the first structural insight into fish cytokines. Tetrapods possess two types of IFNs which play an immediate antiviral role: type I IFNs (e.g. IFN-? and IFN-?) and type III IFNs (IFN-?), and each type is characterized by its specific receptor usage. Similarly, two groups of antiviral IFNs with distinct receptors exist in fish, including zebrafish. IFN1 and IFN2 represent group I and group II, respectively. Nevertheless, both structures reported here reveal a characteristic type I IFN architecture with a straight F helix, as opposed to the remaining class II cytokines including IFN-?, where helix F contains a characteristic bend. Phylogenetic trees derived from structure-guided multiple alignments confirmed that both groups of fish IFNs are evolutionarily closer to type I than to type III tetrapod IFNs. Thus, these fish IFNs belong to the type I IFN family. Our results also imply that a dual antiviral IFN system has arisen twice during vertebrate evolution.

Hamming, Ole Jensen; Lutfalla, Georges

2011-01-01

203

Few non-minimal types and non-structure  

CERN Document Server

We pay two debts from [Sh:576] (math.LO/9805146). The main demands little knowledge from [Sh:576], just quoting a model theoretic consequence of the weak diamond. We assume that K has amalgamation in lambda, and that the minimal types are not dense to get many non-isomorphic models in lambda^+. For this also pcf considerations are relevant. The minor debt was the use in one point of [Sh:576] of lambda not= aleph_0, it is minor as for this case by [Sh:88] we ``usually'' know more.

Shelah, S

1999-01-01

204

Electron diffraction identification of structure types of martensite in Cu-Zn-Al alloys.  

Science.gov (United States)

Electron diffraction technique for identifying structure types of martensite in beta-Hume-Rothery alloys is described. It includes determination of the stacking sequence of the martensite of the basal planes, differentiation of the long-range ordering in martensite inherited from its parent phase (A2 type disordered; B2 type ordered; and D03, or Heusler, type ordered), and distinguishing between normal-type and modified-type martensite. In addition to the 18R1-type martensite, 12R, 6R, and 2H martensites were found in quenched Cu-Zn-Al alloys using this technique. PMID:3505596

Wang, R H; Zhao, Y C; Gui, J A

1987-12-01

205

Electronic structure and physical properties of Ba8Ga16Sn30 clathrates with type-I and type-VIII structure  

International Nuclear Information System (INIS)

A joint experimental and theoretical investigation is performed for Ba-Sn-Ga type-I and type-VIII clathrates. The type-I sample shows a semiconductor characteristic which is accords with the first principle simulation. The type-I clathrate follows Zintl-like behaviour and the semiconducting gap is about 0.6 eV which is agreement with measurement. For the type-VIII clathrate, the simulation shows that a complicated band structure around Fermi level. For the density of states, a peak appears in the fundamental gap, which corresponds to hybridization of Ba bonding orbitals and Sn(Ga) network. A superconducting transition at TC=4 K is observed, which is close to the TC of Sn. An alternative explanation is superconductivity in type-VIII sample arises from increase of electronic density of states around Fermi level EF in the BCS theoretical frame

206

Understanding the Structural Scaling Relations of Early-Type Galaxies  

CERN Document Server

We use a large suite of hydrodynamical simulations of binary galaxy mergers to construct and calibrate a physical prescription for computing the effective radii and velocity dispersions of spheroids. We implement this prescription within a semi-analytic model embedded in merger trees extracted from the Bolshoi Lambda-CDM N-body simulation, accounting for spheroid growth via major and minor mergers as well as disk instabilities. We find that without disk instabilities, our model does not predict sufficient numbers of intermediate mass early-type galaxies in the local universe. Spheroids also form earlier in models with spheroid growth via disk instabilities. Our model correctly predicts the normalization, slope, and scatter of the low-redshift size-mass and Fundamental Plane relations for early type galaxies. It predicts a degree of curvature in the Faber-Jackson relation that is not seen in local observations, but this could be alleviated if higher mass spheroids have more bottom-heavy initial mass functions....

Porter, Lauren A; Primack, Joel R; Johansson, Peter H

2014-01-01

207

Understanding the structural scaling relations of early-type galaxies  

Science.gov (United States)

We use a large suite of hydrodynamical simulations of binary galaxy mergers to construct and calibrate a physical prescription for computing the effective radii and velocity dispersions of spheroids. We implement this prescription within a semi-analytic model embedded in merger trees extracted from the Bolshoi ? cold dark matter N-body simulation, accounting for spheroid growth via major and minor mergers and disc instabilities. We find that without disc instabilities, our model does not predict sufficient numbers of intermediate-mass early-type galaxies in the local Universe. Spheroids also form earlier in models with spheroid growth via disc instabilities. Our model correctly predicts the normalization, slope, and scatter of the low-redshift size-mass and Fundamental Plane relations for early-type galaxies. It predicts a degree of curvature in the Faber-Jackson relation that is not seen in local observations, but this could be alleviated if higher mass spheroids have more bottom-heavy initial mass functions. The model also correctly predicts the observed strong evolution of the size-mass relation for spheroids out to higher redshifts, as well as the slower evolution in the normalization of the Faber-Jackson relation. We emphasize that these are genuine predictions of the model since it was tuned to match hydrodynamical simulations and not these observations.

Porter, L. A.; Somerville, R. S.; Primack, J. R.; Johansson, P. H.

2014-10-01

208

Type of structure of men body engaged in baseball  

Digital Repository Infrastructure Vision for European Research (DRIVER)

An attempt to define the features of structure of sportsmen body - members of collapsible command of Poland on baseball is in-process undertaken (n=20). Age of sportsmen was in a range 18-25 years, and training experience - 7-14 years. Five coefficients (Rohrera, Queteleta II, Manouvrier, growing-gravimetric, pelvic-humeral), and also general surface of body, are certain. Specific gravity of body is expected on the basis of measurings dermic-fatty folds by the use of prognostic equalization o...

Jagiello Wladyslaw; Jagiello Marina.; Kozina Zh.L.

2012-01-01

209

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

210

The structure and dynamics of bubble-type vortex breakdown  

Science.gov (United States)

A unique discrete form of the Navier-Stokes equations for unsteady, three-dimensional, incompressible flow has been used to study vortex breakdown numerically. A Burgers-type vortex was introduced along the central axis of the computational domain, and allowed to evolve in space and time. By varying the strength of the vortex and the free stream axial velocity distribution, using a previously developed Rossby number criterion as a guide, the location and size of the vortex breakdown region was controlled. While the boundaries of the vortex breakdown bubble appear to be nominally symmetric, the internal flow field is not. Consequently, the mechanisms for mixing and entrainment required to sustain the bubble region are different from those suggested by earlier axisymmetric models. Results presented in this study, for a Reynolds number of 200, are in good qualitative agreement with higher Reynolds number experimental observations, and a variety of plots have been presented to help illuminate the fluid physics.

Spall, R. E.; Ash, R. L.; Gatski, T. B.

1990-01-01

211

Structural Analysis of Botulinum Neurotoxin Type G Receptor Binding  

Energy Technology Data Exchange (ETDEWEB)

Botulinum neurotoxin (BoNT) binds peripheral neurons at the neuromuscular junction through a dual-receptor mechanism that includes interactions with ganglioside and protein receptors. The receptor identities vary depending on BoNT serotype (A-G). BoNT/B and BoNT/G bind the luminal domains of synaptotagmin I and II, homologous synaptic vesicle proteins. We observe conditions under which BoNT/B binds both Syt isoforms, but BoNT/G binds only SytI. Both serotypes bind ganglioside G{sub T1b}. The BoNT/G receptor-binding domain crystal structure provides a context for examining these binding interactions and a platform for understanding the physiological relevance of different Syt receptor isoforms in vivo.

Schmitt, John; Karalewitz, Andrew; Benefield, Desire A.; Mushrush, Darren J.; Pruitt, Rory N.; Spiller, Benjamin W.; Barbieri, Joseph T.; Lacy, D. Borden (Vanderbilt); (MCW)

2010-10-19

212

Forced vibration tests on three types of embedded structures (embedment effect test on soil-structure interaction)  

International Nuclear Information System (INIS)

A series of Model Tests of Embedment Effect on Reactor Buildings has been carried out by the Nuclear Power Engineering Corporation (NUPEC), under the sponsorship of the Ministry of International Trade and Industry (MITI) of Japan. Sinusoidal forced vibration tests were carried out on three types of large-scale models to study the embedment effect on dynamic soil-structure interaction. The differences in the resonance curves and the impedance functions were discussed in relation to the vibration characteristics of the respective structures. The embedment effects on the structural responses vary according to the stiffness of the structure. The responses of the structures can be evaluated by the Axisymmetric FEM analyses. (author)

213

Correlation of predicted and measured thermal stresses on a truss-type aircraft structure  

Science.gov (United States)

A test structure representing a portion of a hypersonic vehicle was instrumented with strain gages and thermocouples. This test structure was then subjected to laboratory heating representative of supersonic and hypersonic flight conditions. A finite element computer model of this structure was developed using several types of elements with the NASA structural analysis (NASTRAN) computer program. Temperature inputs from the test were used to generate predicted model thermal stresses and these were correlated with the test measurements.

Jenkins, J. M.; Schuster, L. S.; Carter, A. L.

1978-01-01

214

Crystal structures and magnetic properties of iron (III)-based phosphates: Na4NiFe(PO4)3 and Na2Ni2Fe(PO4)3  

International Nuclear Information System (INIS)

Graphical abstract: A perspective view of the Na2Ni2Fe(PO4)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 Na4NiFe(PO4)3 and Na2Ni2Fe(PO4)3. ? Magnetism behaviours of Na4NiFe(PO4)3 and Na2Ni2Fe(PO4)3. ? Antiferromagnetism interactions. ? Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na4NiFe(PO4)3 (I) and Na2Ni2Fe(PO4)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, R1 = 0.041, wR2=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, ? = 113.66(4)o, R1 = 0.043, wR2=0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O6] octahedra and [PO4] tetrahedra forming [NiFe(PO4)3]4+ units which align in chains along the c-axis. The Na+ cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni2O10] units of edge-sharing [NiO6] octahedra, which alternate with [FeO6] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na+. 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 ?-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 ? 19 kOe, revealed in the hysteresis loop measured at 5 K. This transition is most probably associated with a spin-flop transition.

215

Correlation between laminar structure and crystal lattice in type-1 superconductors due to elastic interaction  

International Nuclear Information System (INIS)

The effect of the anisotropic magnetoelastic energy on the correlation between the laminar structure and the crystal lattice in the intermediate state of the type-I superconductors is investigated. (Auth.)

216

Structural investigations of the f-electron based AB2 type compounds under high pressure  

International Nuclear Information System (INIS)

Systematic structural investigation of the f-electron based compounds under high pressure is of vital importance in understanding their electronic structure, in predicting phase transitions and in finding the transition mechanisms. In this paper, the recent results of high pressure x-ray diffraction studies on some AB2 type compounds, especially, the dialuminides of the rare-earth and the actinides are reported. Whereas the dialuminides of the rare-earths, namely, LaAl2, CeAl2 and GdAl2 (all the MgCu2 type structure at NTP) are found to be stable up to ? 30 GPa, that of the actinides, ThAl2 and UAl2, exhibit interesting structural phase transitions. ThAl2, which stabilizes in the hexagonal AlB2 type structure at NTP, first undergoes an isostructural transition, possibly of electronic origin, at ? 5.5 GPa with a volume collapse of ? 2%. Then it transforms to the orthorhombic Si2 type structure at ? 12 GPa and subsequently to the tetragonal ThSi2 type structure at ? 25 GPa. UAl2 with the cubic MgCu2 type structure at NTP, transforms to the hexagonal MgNi2 type structure at ? 11 GPa. By drawing an analogy with other pseudobinary Laves phase compounds, which exhibit some systematic structural sequence as a function of N, the number of free electron per formula unit AB2, it is expected that it may t, it is expected that it may transform back to the MgCu2 type structure at higher pressure. On the basis of similar arguments, it is expected that most of the AB2 Laves phase compounds of the f-electron based systems may undergo the pressure induced structural sequence: MgCu2 ? MgNi2 (or MgZn2) ? MgCu2 due to the increased delocalization of the f-electron states and their hybridization with the other orbitals. It is also shown that these three Laves phase structures and the structural sequence observed in ThAl2 are subsets of a larger structural sequence as a function of N

217

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

Directory of Open Access Journals (Sweden)

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.

J. Adamczyk

2006-04-01

218

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

Directory of Open Access Journals (Sweden)

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.

Wilcox Elizabeth

2006-07-01

219

Zeolite structure type EAB: Crystal structure and mechanism for the topotactic transformation of the Na, TMA form  

Science.gov (United States)

Synthetic zeolite (Na, TMA)-E represents a new structure type designated EAB. Detailed structure analyses based on X-ray powder diffraction data have been carried out at room temperature, 220°C, and 350°C. The silicate framework, having maximum symmetry {P6 3}/{mmc}, consists of parallel 6-rings in ABBACC sequence as opposed to AABAAC in erionite (with which it has mistakenly been identified). Large changes in conformation of the EAB framework precede the transformation of (Na, TMA)-E to a sodalite-type product above 360°C. There are also strong indications for this reaction to be topotactic, whereby only one-twelfth of the original siloxane bridges are broken. Details of an acid-base reaction mechanism proceeding in characteristic loops of the structure are discussed. This process brings about the inversion of one-third of the tetrahedra in the silicate framework. The presence of water appears to be essential in this model-type reaction.

Meier, W. M.; Groner, M.

1981-04-01

220

Experimental Study on Local Scour in the Downstream Area of Low Drop Structure Types  

Directory of Open Access Journals (Sweden)

Full Text Available Although ecologically disadvantageous since a river is interrupted because of drop structure installation, such structure installation is also deemed ecologically advantageous in terms of scour and complex flows in the direct downstream area. This study started from the premise that scour hole carries value as a habitat and sought to analyze quantitatively the local scour adjustment possibility in the downstream area through drop structure type change and to offer a habitat through scouring. This study provided changes in drop structure types, such as straight line type and V type. For local scour analysis impacting the downstream area by drop structure type, quantitative analysis of scour scope, depth, and length was comparatively performed for a tentative physical habitat through hydraulic experiments. As a result of the experiments, this study found that scour scope increases and various water depth conditions are offered as the angle of the drop structure’s apex becomes smaller. Future studies accompanied by various fish habitation evaluations are considered useful in finding an alternative to upgrade the ecological environment.

Changsung Kim

2012-08-01

 
 
 
 
221

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

Directory of Open Access Journals (Sweden)

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.

O.R. Nandagopan

2013-07-01

222

Crystal structure analysis of Scheelite and Zircon type thorium germanates: A neutron diffraction study  

International Nuclear Information System (INIS)

In this communication we report the detailed crystal structure of two polymorphs of ThGeO4 (scheelite and zircon type) by Rietveld refinement of the neutron diffraction data of polycrystalline samples. Both of crystal structures consist of ThO8 (bisdisphenoid) and GeO4 tetrahedra. Scheelite type structure is a meta-stable polymorph and densely packed lattice, with a little larger average bond lengths of Th-O and Ge-O bonds to accommodate better packing. This is responsible for zircon to scheelite transformation under pressure. However, the average anion-anion contact and cation-cation contacts are shorter in scheelite structure compared to the zircon structure, which would causes the meta-stability in the scheelite structure

223

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

224

Dissipative soliton generation in an active ring resonator based on magnonic quasicrystal with Fibonacci type structure  

Science.gov (United States)

This study reports on the experimental investigations of a magnetostatic surface wave (MSSW) propagation in a magnonic quasicrystal (MQC) with Fibonacci type structure. It is shown that such structure has a greater number of band gaps and narrower pass bands located between them than a periodic structure. These features of the MQC and three-wave decay of the MSSW are used in a MQC active ring resonator for the eigenmode selection and dissipative soliton self-generation.

Grishin, S. V.; Beginin, E. N.; Sharaevskii, Yu. P.; Nikitov, S. A.

2013-07-01

225

Synthesis and crystal structure of three silver indium double phosphates  

Science.gov (United States)

Three new silver indium double phosphates Ag 3In(PO 4) 2 (I), ?-(II) and ?-Ag 3In 2(PO 4) 3 (III) were synthesized by solid state method (I and II—700 °C, III—900 °C). Compounds I and II crystallize into a monoclinic system (I—sp. gr. C2/ m, Z=2, a=8.7037(1)Å, b=5.4884(1)Å, c=7.3404(1)Å, ?=93.897(1)°; II—sp. gr. C2/ c, Z=4, a=12.6305(1)Å, b=12.8549(1)Å, c=6.5989(1)Å, ?=113.842(1)°), and compound III crystallize into a hexagonal system (sp. gr. R-3 c, Z=6, a=8.9943(1)Å, c=22.7134(1)Å). Their crystal structures were determined by the Rietveld analysis (I— R=6.47, R=8.54; II— R=5.67, R=6.40; III— R=7.30, R=9.91). Structure of Ag 3In(PO 4) 2 is related to the sodium chromate structure type and is isotypic to ?-Na 3In(PO 4) 2. The polymorphous modifications of ?- and ?-Ag 3In 2(PO 4) 3 are isostructural to sodium analogs ( ?- and ?-Na 3In 2(PO 4) 3) and are related to alluaudite (II) and NASICON (III) structure types. Compounds I and II are not stable at temperature above 850 °C. Ag 3In(PO 4) 2 is decomposed providing silver orthophosphate Ag 3PO 4 and ?-Ag 3In 2(PO 4) 2. ?-Ag 3In 2(PO 4) 3 is transformed to ?-Ag 3In 2(PO 4) 3.

Strelkov, M. A.; Zhizhin, M. G.; Komissarova, L. N.

2006-12-01

226

Effect of an anionic surfactant on different type of hydrate structures  

Energy Technology Data Exchange (ETDEWEB)

In this study, methane and gas mixture (including 88.17% propane) hydrates were produced from the anionic surfactant solutions of 0.00, 0.01 and 0.05 wt.% to investigate the effect of surfactant on the hydrate formation rate. Hydrate formation rate increases (promotion effect) with surfactant concentration, but the extent of the surfactant effect is closely related with the type of hydrate structure. The increase in the hydrate formation rate of sII type structure is relatively small compared to that obtained with structure sI.

Karaaslan, Ugur; Uluneye, Evrim; Parlaktuna, Mahmut [Department of Petroleum and Natural Gas Engineering, Middle East Technical University, 06531 Ankara (Turkey)

2002-07-01

227

Structure integrity analysis of Type III iodine absorber of active carbon  

International Nuclear Information System (INIS)

An active carbon absorber is mainly used for radioactive iodine absorption and gas purification in an nuclear power plant. According to technical requirement of the Type III absorber developed at Shanghai Nuclear Engineering Research and Design Institute, finite element analysis (FEA) was used for its mechanics analysis. Static analysis under dead weight, design pressure and operating pressure, modal analysis, and seismic analysis were performed. The structure integrity of Type III active carbon iodine absorber was satisfied under different service conditions. The structure weakness was clarified under static and seismic loads,and the structure design was improved based on the FEA results. (authors)

228

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2007-09-15

229

Subaortic (Type 6 Muscular Band—Innocent Bystander or Pathologic Structure?  

Directory of Open Access Journals (Sweden)

Full Text Available Intraventricular tendons are structures that was identified more than a hundred years ago. It has been suggested that they represent intracavitary radiations of the bundle of His and that they may be an isolated finding or be associated with structural cardiac abnormalities. Loukas et al divided these structures into five categories and recently a sixth type have been added. Various physiological disturbances have been observed due to the sixth type of tendon, such as ST segment elevation and right bundle branch block. It has been noted that this peculiar structure appears too thick to be called a tendon, thus the term band. This retrospective analysis analyzed the incidence of the thick, subaortic (type 6 muscular band in a cardiovascular clinic.

J Ker

2010-08-01

230

Development, characteristics and comparative structural analysis of tensegrity type cable domes  

Directory of Open Access Journals (Sweden)

Full Text Available Tensegrity type cable domes are three-dimensional structural configurations, prestressed inside the perimeter compression ring, in which the continuous tension throughout the roof structure is made by continuous tension cables and discontinuous compression struts. These kinds of structures can be formed like spatially triangulated networks or like networks nontriangulated in space. This paper examines some effects of network geometry on the behaviour and structural efficiency of tensegrity type cable domes. In this paper the roof cover is considered non-interactive with the supporting structure, unlike rigidly clad tensegrity type cable domes. Since the main bearing elements of tensegrity type cable domes are prestressed cables, they show non-linear load deformation and rely upon geometric stiffness. A geometrically non-linear analysis of non-triangulated and triangulated structures for different load conditions was conducted employing a computer program based on the perturbation theory. The incrementally-iterative procedure, with an approximation of the stiffness matrix by combining the elastic and geometric stiffness matrix, allows detection of structural instabilities.

Nenadovi? Aleksandra

2010-01-01

231

Assembly of Na3V2(PO4)3 nanoparticles confined in a one-dimensional carbon sheath for enhanced sodium-ion cathode properties.  

Science.gov (United States)

Structural and morphological control is an effective approach for improvement of electrochemical properties in rechargeable batteries. One-dimensionally assembled structure composed of NASICON-type Na3 V2 (PO4 )3 nanoparticles were fabricated through an electrospinning method to meet the requirements for the development of efficient electrode materials in Na-ion batteries. High-temperature treatment of electrospun precursor fibers under an argon flow provides a nonwoven fabric of nanowires comprising crystallographically oriented nanoparticles of NASICON-type Na3 V2 (PO4 )3 within a carbon sheath. The mesostructure comprising NASICON-type Na3 V2 (PO4 )3 and carbon give a short sodium-ion transport pass and an efficient electron conduction pass. Electrochemical properties of NASICON-type Na3 V2 (PO4 )3 are improved on the basis of one-dimensional nanostructures designed in the present study. PMID:25123497

Kajiyama, Satoshi; Kikkawa, Jun; Hoshino, Junichi; Okubo, Masashi; Hosono, Eiji

2014-09-22

232

Structure of a fibronectin type III-like module from Clostridium thermocellum.  

Science.gov (United States)

The 1.6 A resolution structure of a fibronectin type III-like module from Clostridium thermocellum (PDB code 3mpc) with two molecules in the asymmetric unit is reported. The crystals used for data collection belonged to space group P2(1)2(1)2(1), with unit-cell parameters a=35.43, b=45.73, c=107.72 A, and the structure was refined to an R factor of 0.166. Structural comparisons found over 800 similar structures in the Protein Data Bank. The broad range of different proteins or protein domains with high structural similarity makes it especially demanding to classify these proteins. Previous studies of fibronectin type III-like modules have indicated that they might function as ligand-binding modules, as a compact form of peptide linkers or spacers between other domains, as cellulose-disrupting modules or as proteins that help large enzyme complexes remain soluble. PMID:20693658

Alahuhta, Markus; Xu, Qi; Brunecky, Roman; Adney, William S; Ding, Shi-You; Himmel, Michael E; Lunin, Vladimir V

2010-08-01

233

La3Ir2 with rhombohedral Er3Ni2-type structure  

International Nuclear Information System (INIS)

La3Ir2 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: Er3Ni2-type structure, R anti 3, a = 895.26(2), c = 1713.01(5) pm, wR = 0.0578, 766 F2 values, 25 variables. The structure is composed of two simple basic building units: slightly distorted La1 rate at La36La22 cubes resembling the tungsten structure and Ir2 rate at La11La22La35 units with an AlB2-related coordination (298 pm Ir-Ir in the dumb-bell). Each cube is coordinated by six of the AlB2 units. The relationship with the U3Si2-type structure is discussed.

234

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

Directory of Open Access Journals (Sweden)

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.

Anggie Angeline

2009-01-01

235

Type V and VI collagen for cohesion of dermal fibrillar structures.  

Science.gov (United States)

Type V and VI collagen were capable to joint each other and with type I and IV collagen, as well as mucopolysaccharides. This capability suggested that these collagens function for cohesion of fibrillar tissue components of dermis. This study demonstrated the locality of these types of collagen in dermis. Fresh specimens of normal skin were fixed in 2% paraformaldehyde in phosphate-buffered saline, overnight. Besides, in order to loosen the twist of collagen fibril, some pieces of the skin specimens were treated by citrate buffer pH 3.0, prior to fixation. The specimens were embedded in Technovit 4100 and the ultrathin sections were stained by antibody to type V collagen and followed by antibody to type I, III, IV and VI collagen. The immune reactant was visualized by gold particles for electron microscopic observation. Type V and VI collagen formed networks in dermis and jointed to collagen fibrils, elastic fibre and basal lamina. Type V collagen was found inside collagen fibrils, broad elastic fibres and junctions. Dermo-epidermal junction showed type V collagen on the dermal aspects of basal lamina and at the sites where anchoring filaments joint to basal lamina, while in junction of mesenchymal tissues, no precise structural components for type V collagen were identified. Type VI collagen wove with type V collagen in dermis and associated with mucopolysaccharides. In conclusion, type V collagen formed networks in dermal interfibrillar space and participated in assembling collagen fibrils and forming broad elastic fibres. Epithelial and mesenchymal cells cohered to the underlying dermal matrix in the junction by type V collagen. Type VI collagen interwove with type V collagen in the interfibrous space and associated with mucopolysaccharides. Types V and VI collagen preserved architecture of dermal matrix. PMID:17784637

Kobayasi, T; Karlsmark, T

2006-01-01

236

In Situ D-periodic Molecular Structure of Type II Collagen  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2010-05-06

237

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

Energy Technology Data Exchange (ETDEWEB)

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 {beta}-sheet. When the two sheets are placed on top of each other to form the {beta}-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.

Muhle-Goll, Claudia; Nilges, Michael; Pastore, Annalisa [European Molecular Biology Laboratory (Germany)

1997-01-15

238

Determination of a new structure type in the Sc–Fe–Ge–Sn system  

International Nuclear Information System (INIS)

Highlights: ? A new structure type with the composition Sc4Fe5Ge6.10(3)Sn1.47(2). ? Crystallizes in the space group Immm (No. 71, oI144). ? Sample obtained using a reactive Sn flux. ? Electronic structure calculations indicate polar intermetallic bonding network. - Abstract: A new structure type has been discovered in the system Sc–Fe–Ge–Sn by employing Sn as a flux medium. According to single crystal X-ray diffraction, the new structure has a composition of Sc4Fe5Ge6.10(3)Sn1.47(2) and crystallizes in the space group Immm (No. 71, oI144) with lattice parameters of a = 5.230(1) Å, b = 13.467(3) Å, and c = 30.003(6) Å. The structure is composed of square anti-prismatic clusters that are condensed into zig-zag chains along the [0 1 0] direction. These chains are further condensed through a split Sn/Ge position, forming a three-dimensional network. Magnetization measurements indicate an antiferromagnetic phase transition near 240 K. Electronic structure calculations identified the most favorable bonding network in this new system. Using crystal orbital Hamilton population (COHP) curves and their integrated values (ICOHP), a polar intermetallic bonding network involving Sc–Ge as well as Fe–Sn and Fe–Ge contacts can be assigned to this new structure type.

239

Synergistic microwave and structural studies of C-type Ho2Si2O7  

International Nuclear Information System (INIS)

Highlights: ? The structural properties are finding by using XRD and SEM. ? The DC electrical and microwave properties of C-type Ho2Si2O7 are reported. ? These properties include the dc electrical resistivity as a function of temperature and permittivity at room temperature. ? Both ?' and ?'' decrease slightly as the frequency increases up to 1.5 GHz, after that ?' increases while ?'' decreases as the frequency increases. ? At around 2.45 GHz, a resonance is observed. - Abstract: Ho2Si2O7 material exists in four polymorphs, a triclinic low temperature phase (type-B), a monoclinic modification (type-C), high temperature monoclinic (type-D), and high temperature orthorhombic modification (type-E). The structural properties are measured by XRD and the morphology is noted through scanning electron microscopy (SEM). The dc electrical resistivity (?) as a function of temperature and dielectric properties of C-type Ho2Si2O7 in the microwave region is measured. The activation energy is calculated from ln ? versus 1/kBT plot. The activation energy is 0.119 ± 0.001 eV. Both the real (?') and imaginary parts of permittivity (?'') decrease slightly as the frequency increases up to 1.5 GHz, after that ?' increases while ?'' decreases as the frequency increases. At around 2.45 GHz, resonance is observed.

240

Classification of urban structural types (UST) using multiple data sources and spatial priors  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Remote sensing and geographic information science offer many pos- sibilities in terms of availability of diverse data. Some products like land cover layers or digital elevation models can be extracted from imagery and enable the realization of 3D city models. Starting from these morphological and geographical sources, an approach is proposed to extract information about urban structure types (UST), i.e. types of urban habitat at the neighborhoodscale. We propose an effective processing chain ...

Poncet Montanges, Arnaud

2014-01-01

 
 
 
 
241

Structure-properties relationship of poly(ethylene terephthalate) wool-type fibres  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Two PET wool-type fibres were studied for this research, i.e. a normal wool-type and a low-pilling modification. The structural morphology and crystalline orientation of the fibres were investigated by means of wide-angle x-ray scattering (WAXS), density measurements and infrared (IR) spectroscopy. The degree of crystallinity, crystallite orientation, apparent crystallite dimensions and micro-void system were determined by x-ray scattering. Birefringence measurements were used to study the av...

Sfiligoj-smole, Majda; Z?iberna-s?ujica, Milena; Kurec?ic?, Manja

2012-01-01

242

Structural Phase Transition of Rutile-Type MgH2 at High Pressures  

Science.gov (United States)

The pressure-induced structural phase transition of MgH2 was examined up to 57 GPa at room temperature. ?-MgH2 with the rutile-type structure at ambient conditions transformed to ?-MgH2 with the ?-PbO2 structure. A complete conversion to the ?-phase, however, did not take place and these two phases coexisted up to 9 GPa. Above 9 GPa, MgH2 transformed to the orthorhombic phase (HP1-phase), and further to another orthorhombic phase (HP2-phase) at around 17 GPa. Space groups of the HP1-phase and the HP2-phase were concluded to be Pbc21 and Pnma (cotunnite-type), respectively. Cotunnite-type MgH2 was stable at pressures up to 57 GPa. Thus the proposed structural sequence of MgH2 under pressure is rutile-type ? ?-PbO2 ? Pbc21 ? cotunnite-type, with an increase in the coordination number of magnesium ions from 6 to 9.

Moriwaki, Toru; Akahama, Yuichi; Kawamura, Haruki; Nakano, Satoshi; Takemura, Kenichi

2006-07-01

243

Orthodontic and orthopedic care of adult patients with different types of temporomandibular joint structure  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of the research is to identify types of temporomandibular joint structure by tomogram data and to explain the choice of methods to perform complex treatment of adult patients with dental and facial anomalies and deformations. Temporomandibular joints tomogram images of 106 patients with dental and facial anomalies and deformations served as the research material. The types of temporomandibular joint structure were determined and criteria for treatment choice in adult patients with dental and facial anomalies and deformations were worked out. The data obtained allow improving efficiency of complex (orthodontic and orthopedic treatment of adult patients with dental and facial anomalies and deformations

Listopadov ?.?.

2010-12-01

244

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)

245

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2011-12-31

246

Changes in electronic structure upon lithium insertion into Fe2(SO4)3 and Fe2(MoO4)3 investigated by X-ray absorption spectroscopy.  

Science.gov (United States)

Changes in electronic structure upon electrochemical lithium insertion into two iron compounds, namely, rhombohedral Fe2(SO4)3 with a NASICON-type structure and monoclinic Fe2(MoO4)3, were investigated using X-ray absorption spectroscopy (XAS). Fe K-edge and L(III)- and L(II)-edge XAS revealed that the rearrangement of Fe d electrons or rehybridization of Fe d-O p bonding took place accompanied by the reduction of Fe ions upon Li insertion for both samples and that a larger change in spectra was observed in Fe2(SO4)3. In addition, the changes in the electronic structure of the polyanion units XO4(2-) (X = S or Mo) after Li insertion were also investigated by O K-edge and S K-edge or Mo L(III)-edge XAS. The results indicated that the electronic structure around oxygen markedly changed in Fe2(MoO4)3, while no significant change was observed in Fe2(SO4)3. PMID:17249717

Shirakawa, Junichi; Nakayama, Masanobu; Wakihara, Masataka; Uchimoto, Yoshiharu

2007-02-15

247

Structure/function of the inhibition of human 3beta-hydroxysteroid dehydrogenase type 1 and type 2 by trilostane.  

Science.gov (United States)

The human type 1 (placenta, breast tumors) and type 2 (gonads, adrenals) isoforms of 3beta-hydroxysteroid dehydrogenase/isomerase (3beta-HSD) are key enzymes in biosynthesis of all active steroid hormones. Human 3beta-HSD1 is a critical enzyme in the conversion of DHEA to estradiol in breast tumors and may be a major target enzyme for the treatment of breast cancer. 3beta-HSD2 participates in the production of cortisol and aldosterone in the human adrenal gland. The goals of this project are to evaluate the role of the 2alpha-cyano group on trilostane (2alpha-cyano-4alpha,5alpha-epoxy-17beta-ol-androstane-3-one) and determine which amino acids may be critical for 3beta-HSD1 specificity. Trilostane without the 2alpha-cyano group, 4alpha,5alpha-epoxy-testosterone, was synthesized. Using our structural model of 3beta-HSD1, trilostane or 4alpha,5alpha-epoxy-testosterone was docked in the active site using Autodock 3.0, and the potentially critical residues (Met187 and Ser124) were identified. The M187T and S124T mutants of 3beta-HSD1 were created, expressed and purified. Dixon analyses of the inhibition of wild-type 3beta-HSD1, 3beta-HSD2, M187T and S124T by trilostane and 4alpha,5alpha-epoxy-testosterone suggest that the 2alpha-cyano group of trilostane is anchored by Ser124 in both isoenzymes. Kinetic analyses of cofactor and substrate utilization as well as the inhibition kinetics of M187T and the wild-type enzymes suggest that the 16-fold higher-affinity inhibition of 3beta-HSD1 by trilostane may be related to the presence of Met187 in 3beta-HSD1 and Thr187 in 3beta-HSD2. This structure/function information may lead to the production of more highly specific inhibitors of 3beta-HSD1 to block the hormone-dependent growth of breast tumors. PMID:18524572

Thomas, James L; Mack, Vance L; Glow, Jason A; Moshkelani, Delaram; Terrell, J Ross; Bucholtz, Kevin M

2008-07-01

248

Structure of the orthorhombic phase of Li1+xTi2-xInxP3O12, x=1.08  

International Nuclear Information System (INIS)

Li1+xTi2-xInxP3O12 is orthorhombic for 0.4r=467.42, a=8.647(2), b=8.807(2), c=24.328(3) A, Z=4, V=1852.7 A3, Dx=3.35 Mg m-3, MoK?, ?=0.7107 A, ?=1.94 mm-1, F(000)=872, T=298 K, R=4.7% for 1265 observed reflections. The structure of the title compound consists of basic units: Three PO4 tetrahedra spanning the six corners of two MO6 octahedra; the basic units are in turn linked together forming a three-dimensional [Ti2-xInxP3O12] framework in which the M site is randomly occupied by Ti4+ and In3+. This arrangement is locally similar to that of the Nasicon framework. However, the orthorhombic structure is actually an intergrowth of Nasicon and anti-Nasicon blocks. (orig.)

249

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

Science.gov (United States)

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

Fleischer, Everly B; Janda, Kenneth C

2013-05-16

250

Structural Insights into the Assembly of the Type III Secretion Needle Complex  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type III secretion systems (TTSSs) mediate translocation of virulence factors into host cells. We report the 17-angstrom resolution structures of a central component of Salmonella typhimurium TTSS, the needle complex, and its assembly precursor, the bacterial envelope–anchored base. Both the base and the fully assembled needle complex adopted multiple oligomeric states in vivo, and needle assembly was accompanied by recruitment of the protein PrgJ as a structural component of the base. More...

Marlovits, Thomas C.; Kubori, Tomoko; Sukhan, Anand; Thomas, Dennis R.; Gala?n, Jorge E.; Unger, Vinzenz M.

2004-01-01

251

Stability of Fe-based alloys with structure type C6Cr23  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bulk metallic glass forms when liquid metal alloys solidify without crystalization. In the search for Iron-based bulk glass-forming alloys of the metal-metalloid type (Fe-B- and Fe-C-based), crystals based on the structural prototype C6Cr23 often preempt the amorphous phase. Destabilizing this competing crystal structure could enhance glass-formability. We carry out first-principles total energy calculations of enthalpy of formation to identify third elements that can effect...

Widom, M.; Mihalkovic, M.

2004-01-01

252

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 t...

Castejo?n, L.; Jime?nez, M. A.; Miravete, A.

1997-01-01

253

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 u...

Igor Tomi?i?; Ana ?ori?; Marina Kla?mer ?alopa

2012-01-01

254

Structure, Stoichiometry and Stability in Magnetoplumbite and Beta-Alumina Type Ceramics.  

Science.gov (United States)

The crystal defect chemistry and phase stability of ceramic oxides based on the complex magnetoplumbite (MP) or beta-alumina (beta ) structure are investigated by computer-based atomistic simulation techniques. Work has focused on a number of systems, including barium hexaaluminates (BHA), lanthanum hexaaluminate (LHA), lanthanum magnesium hexaaluminate (LMA), and sodium lanthanum hexaaluminates (SLA). The calculations are able to discriminate between various models for the defect structures in these systems and shed some interesting light on the energetics underlying the nonstoichiometry and phase equilibria displayed by these systems. Our results suggest that BHA will not be stable in the MP phase but will form a mixture of the two nonstoichiometric phases with beta-type structures. Our calculations show that the most appropriate structural model for the nonstoichiometry of the BHA phase II is the one which includes both triple Reidinger defects and Ba interstitials inside the spinel blocks. Our calculations suggest that LHA will form an MP-type nonstoichiometric phase rm La_ {0.83}Al_{11.83}O_{19 }, which has the defect complex composed of a pair of vacancies, V_{rm La } and V_{rm Al}, on the mirror plane, and a pair of Al Frenkel defects formed above and below the center of the vacancy pair. It is also revealed that there is a great possibility of existence of metastable phases. It is seen, however, that beta-type or beta-MP -mixed-type LHA phases are not likely. Our calculations reveal that the defect energetics in LMA are much influenced by the distribution of Mg ions, which prefer the spinel block tetrahedral sites in the MP structure. It is found that the Mg ions suppress the formation of defect complexes in the mirror plane region, and thus stabilize the MP structure. Several nonstoichiometric defect processes feasible in LMA are proposed. Our calculations suggest that SLA will form various nonstoichiometric phases, the structures of which are composed of two structural units stacking alternatively in the c direction, the beta-type half cell and the MP-structured LHA-type half cell. Several defect mechanisms in SLA, by which various nonstoichiometries are accommodated into the ideal P and MP structures, are proposed.

Park, Jae-Gwan

1995-01-01

255

The Radio Structure and Properties of a sample of Early-Type Seyfert Galaxies  

Science.gov (United States)

We have observed all Seyferts from the catalogs of Hewit & Burbidge (1991), Huchra (1989), & Veron-Cetty and Veron (1991) with morphological types earlier than S0/a, recessional velocities less than 7,000 km s(-1) , visual magnitudes less than 14.5, and declinations greater than --45{\\arcdeg} with the VLA at 3.6 and 20 cm. The sample consists of 47 newly observed galaxies and 3 objects with radio data taken from the literature. This data forms part of a homogeneous high-resolution imaging database of early-type Seyferts; high resolution emission line ([OIII] and H? +[NII]) and broad-band (green) imaging of this sample has been completed in a previous project (Mulchaey, Wilson, & Tsvetanov 1996). The axes of the emission line gas and of the radio structure are correlated with no significant variation with Hubble type. There is no significant difference between the mean radio luminosity of Seyfert 1's and Seyfert 2's in the early-type sample. The radio luminosity of early-type Seyferts is similar to that of late-type Seyferts. Correlations between Seyfert type, radio structure and host galaxy P.A.'s, galaxy orientation and luminosity will be discussed in the poster.

Nagar, N. M.; Wilson, A. S.; Mulchaey, J.; Gallimore, J.

1997-12-01

256

Two types of dynamic cool coronal structures observed with STEREO and Hinode  

International Nuclear Information System (INIS)

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. We report on the discovery of two types of dynamic cool coronal structures, and characterize their fundamental properties. Using the EUV 304 A images from the Extreme Ultra Violet 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 A observations show that a missile-like plasmoid moves along an arch-shaped trajectory, with an average velocity of 31 km s-1. 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's feet. During the arch formation and disappearance, SOT Ca II images explore dynamic cool coronal structures beneath the arch. By tracking these structures, we classify them into two types. Type I is threadlike in shape and flows downward with a greater average velocity of 72 km s -1; finally it combines with a loop fibril at a chromospheric altitude. Type II is shape-transformable and sometimes rolling as it flows downward with a smaller velocity of 37 km s -1, thller velocity of 37 km s -1, then disappears insularly in the chromosphere. It is suggested that the two types of structures are possibly controlled by different magnetic configurations.

257

Two types of dynamic cool coronal structures observed with STEREO and Hinode  

Science.gov (United States)

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. We report on the discovery of two types of dynamic cool coronal structures, and characterize their fundamental properties. Using the EUV 304 Å images from the Extreme Ultra Violet 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 A observations show that a missile-like plasmoid moves along an arch-shaped trajectory, with an average velocity of 31 km s-1. 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's feet. During the arch formation and disappearance, SOT Ca II images explore dynamic cool coronal structures beneath the arch. By tracking these structures, we classify them into two types. Type I is threadlike in shape and flows downward with a greater average velocity of 72 km s -1 finally it combines with a loop fibril at a chromospheric altitude. Type II is shape-transformable and sometimes rolling as it flows downward with a smaller velocity of 37 km s -1, then disappears insularly in the chromosphere. It is suggested that the two types of structures are possibly controlled by different magnetic configurations.

Zhang, Jun; Li, Le-Ping

2009-12-01

258

Electronic structures of Plutonium compounds with the NaCl-type monochalcogenides structure  

International Nuclear Information System (INIS)

We calculate the energy band structure and the Fermi surface of PuS, PuSe and PuTe by using a self-consistent relativistic linear augmented-plane-wave method with the exchange and correlation potential in a local density approximation. It is found in common that the energy bands in the vicinity of the Fermi level are mainly due to the hybridization between Pu 5/ and monochalcogenide p electrons. The obtained main Fermi surfaces are composed of two hole sheets and one electron sheet, all of which are constructed from the band having the Pu 5/ state and the monochalcogenide p state.

259

Structural studies of apatite-type oxide ion conductors doped with Cobalt  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A series of Co doped lanthanum silicate apatite-type phases, La9.83Si4.5Co1.5O26, La9.66Si5CoO26, La10Si5CoO26.5 and La8BaCoSi6O26, have been synthesised, and neutron diffraction, EXAFS and XANES used to investigate their structures in detail. All compositions were shown to possess the hexagonal apatite structure, and the results confirmed that cobalt can be doped onto both the La and Si sites within the structure depending on the starting composition. The Co doping is shown to cause consi...

Tolchard, Julian; Sansom, Jonathan; Islam, Saiful; Slater, Peter

2005-01-01

260

Hierarchical structures in AB/AC type diblock-copolymer blend particles.  

Science.gov (United States)

This paper describes the first preparation of diblock-copolymer blend particles with hierarchical inner structures. AB/AC type diblock-copolymer blend particles were successfully prepared by a simple solvent evaporation method. The inner phase separation structures can be controlled by changing the molecular weight combinations of common polymer segments. Furthermore, the one-to-one blend of two diblock-copolymers formed Janus particles with two different domains of microphase separation. Pd ions were successfully introduced into the particles with the onion-like structure. These organic-inorganic composite particles can be used as a novel class of nanomaterials applicable to photonics and electronics. PMID:20680197

Yabu, Hiroshi; Motoyoshi, Kiwamu; Higuchi, Takeshi; Shimomura, Masatsugu

2010-10-14

 
 
 
 
261

Structural evolution and electronic properties of n-type doped hydrogenated amorphous silicon thin films  

Science.gov (United States)

The relationship between structure and electronic properties of n-type doped hydrogenated amorphous silicon (a-Si:H) thin films was investigated. Samples with different features were prepared by plasma enhanced chemical vapor deposition (PECVD) at various substrate temperatures. Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy were used to evaluate the structural evolution, meanwhile, electronic-spin resonance (ESR) and optical measurement were applied to explore the electronic properties of P-doped a-Si:H thin films. Results reveal that the changes in materials structure affect directly the electronic properties and the doping efficiency of dopant.

He, Jian; Li, Wei; Xu, Rui; Qi, Kang-Cheng; Jiang, Ya-Dong

2011-12-01

262

A note on the prolongation structure of the cubically nonlinear integrable Camassa-Holm type equation  

Science.gov (United States)

In this Letter, we formulate an exterior differential system for the newly discovered cubically nonlinear integrable Camassa-Holm type equation. From the exterior differential system we establish the integrability of this equation. We then study Cartan prolongation structure of this equation. We also discuss the method of identifying conservation laws and Bäcklund transformation for this equation from the identified exterior differential system.

Stalin, S.; Senthilvelan, M.

2011-10-01

263

Structure and Evolutionary Origin of Ca2+-Dependent Herring Type II Antifreeze Protein  

Energy Technology Data Exchange (ETDEWEB)

In order to survive under extremely cold environments, many organisms produce antifreeze proteins (AFPs). AFPs inhibit the growth of ice crystals and protect organisms from freezing damage. Fish AFPs can be classified into five distinct types based on their structures. Here we report the structure of herring AFP (hAFP), a Ca2+-dependent fish type II AFP. It exhibits a fold similar to the C-type (Ca2+-dependent) lectins with unique ice-binding features. The 1.7 Angstroms crystal structure of hAFP with bound Ca2+ and site-directed mutagenesis reveal an ice-binding site consisting of Thr96, Thr98 and Ca2+-coordinating residues Asp94 and Glu99, which initiate hAFP adsorption onto the [10-10] prism plane of the ice lattice. The hAFP-ice interaction is further strengthened by the bound Ca2+ through the coordination with a water molecule of the ice lattice. This Ca2+-coordinated ice-binding mechanism is distinct from previously proposed mechanisms for other AFPs. However, phylogenetic analysis suggests that all type II AFPs evolved from the common ancestor and developed different ice-binding modes. We clarify the evolutionary relationship of type II AFPs to sugar-binding lectins.

Liu,Y.; Li, Z.; Lin, Q.; Kosinski, J.; Seetharaman, J.; Bujnicki, J.; Sivaraman, J.; Hew, C.

2007-01-01

264

Study of interfaces chemistry in type-II GaSb/InAs superlattice structures  

Energy Technology Data Exchange (ETDEWEB)

There is a considerable interest in type-II GaSb/InAs superlattice system due to several modern applications including infrared detectors. In these studies X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE) have been used for extensive characterization of the surface and interface of GaSb/InAs superlattice. Application of XPS and SE techniques provides precise information from topmost layers of structure and allows excluding presence of GaAs-type interfaces in GaSb/InAs superlattices. It means that Sb-for-As anion exchange does not exist during the molecular beam epitaxial growth of superlattice structures. Simultaneously, these results indicate that InSb-type or GaInSb-type interfaces have been detected in the structures studied. - Highlights: Black-Right-Pointing-Pointer The complementary study of InAs/GaSb superlattice interfaces has been proposed. Black-Right-Pointing-Pointer InSb and GaInSb interfaces in InAs/GaSb superlattices have been shown. Black-Right-Pointing-Pointer The presence of GaAs-type interface in InAs/GaSb superlattices was excluded. Black-Right-Pointing-Pointer Sb-for-As exchange during InAs/GaSb superlattice epitaxial growth does not exist.

Papis-Polakowska, E., E-mail: papis@ite.waw.pl [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Kaniewski, J. [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Szade, J. [A. Chelkowski Institute of Physics, University of Silesia ul. Uniwersytecka 4, 40-007 Katowice (Poland); Rzodkiewicz, W.; Jasik, A.; Reginski, K. [Institute of Electron Technology, Al. Lotnikow 32/46, 02-668 Warsaw (Poland); Wawro, A. [Institute of Physics, Polish Academy of Sciences, Al. Lotnikow 32/46, 02-668 Warsaw (Poland)

2012-11-01

265

Study of interfaces chemistry in type-II GaSb/InAs superlattice structures  

International Nuclear Information System (INIS)

There is a considerable interest in type-II GaSb/InAs superlattice system due to several modern applications including infrared detectors. In these studies X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry (SE) have been used for extensive characterization of the surface and interface of GaSb/InAs superlattice. Application of XPS and SE techniques provides precise information from topmost layers of structure and allows excluding presence of GaAs-type interfaces in GaSb/InAs superlattices. It means that Sb-for-As anion exchange does not exist during the molecular beam epitaxial growth of superlattice structures. Simultaneously, these results indicate that InSb-type or GaInSb-type interfaces have been detected in the structures studied. - Highlights: ? The complementary study of InAs/GaSb superlattice interfaces has been proposed. ? InSb and GaInSb interfaces in InAs/GaSb superlattices have been shown. ? The presence of GaAs-type interface in InAs/GaSb superlattices was excluded. ? Sb-for-As exchange during InAs/GaSb superlattice epitaxial growth does not exist.

266

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)

267

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

Directory of Open Access Journals (Sweden)

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.

Igor Tomi?i?

2012-12-01

268

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

Science.gov (United States)

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

Zeier, Wolfgang G

2014-10-14

269

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)

270

Crystal structure of a type II dehydroquinate dehydratase-like protein from Bifidobacterium longum.  

Science.gov (United States)

Dehydroquinate dehydratase (DHQD) catalyzes the third step in the biosynthetic shikimate pathway. Here we identify a Bifidobacterium longum protein with high sequence homology to type II DHQDs but no detectable DHQD activity under standard assay conditions. A crystal structure reveals that the B. longum protein adopts a DHQD-like tertiary structure but a distinct quaternary state. Apparently forming a dimer, the B. longum protein lacks the active site aspartic acid contributed from a neighboring protomer in the type II DHQD dodecamer. Relating to the absence of protein-protein interactions established in the type II DHQD dodecameric assembly, substantial conformational changes distinguish the would-be active site of the B. longum protein. As B. longum possess no other genes with homology to known DHQDs, these findings imply a unique DHQD activity within B. longum. PMID:23539270

Light, Samuel H; Krishna, Sankar N; Bergan, Raymond C; Lavie, Arnon; Anderson, Wayne F

2013-03-01

271

Electronic structure of p-type (Ga,Fe)N diluted magnetic semiconductors  

Energy Technology Data Exchange (ETDEWEB)

By ab-initio calculation we show that the (Ga,Fe)N ground state may be changed from anti-ferromagnetic to ferromagnetic by acceptor defect like Ga vacancies. The electronic structures are calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that we can increase the magnetic moment of Fe in p-type GaN by oxygen co-doping. Mechanism of exchange interactions between magnetic ions in p-type (Ga,Fe)N is also studied. The effect of external magnetic field on the electronic structure of (Ga, Fe)N and p-type (Ga, Fe)N is investigated.

Mounkachi, O. [Laboratoire de Magnetisme et de Physique des Hautes Energies, Departement de physique, Faculte des sciences, B.P. 1014, Rabat (Morocco); Benyoussef, A. [Laboratoire de Magnetisme et de Physique des Hautes Energies, Departement de physique, Faculte des sciences, B.P. 1014, Rabat (Morocco); Hassan II Academy of Sciences and Technology, Rabat (Morocco); The Institute of Nanotechnology, INANOTECH, Rabat (Morocco); El Kenz, A. [Laboratoire de Magnetisme et de Physique des Hautes Energies, Departement de physique, Faculte des sciences, B.P. 1014, Rabat (Morocco)], E-mail: elkenz@fsr.ac.ma; Saidi, E.H. [Laboratoire de Physique des Hautes Energies, Departement de physique, Faculte des sciences, B.P. 1014, Rabat (Morocco); Hassan II Academy of Sciences and Technology, Rabat (Morocco); The Institute of Nanotechnology, INANOTECH, Rabat (Morocco)

2009-08-15

272

Electronic structure of p-type (Ga,Fe)N diluted magnetic semiconductors  

International Nuclear Information System (INIS)

By ab-initio calculation we show that the (Ga,Fe)N ground state may be changed from anti-ferromagnetic to ferromagnetic by acceptor defect like Ga vacancies. The electronic structures are calculated by using the Korringa-Kohn-Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that we can increase the magnetic moment of Fe in p-type GaN by oxygen co-doping. Mechanism of exchange interactions between magnetic ions in p-type (Ga,Fe)N is also studied. The effect of external magnetic field on the electronic structure of (Ga, Fe)N and p-type (Ga, Fe)N is investigated.

273

Chemical composition and structure of thin PZT-type ferroelectric films  

International Nuclear Information System (INIS)

Using r.f. sputtering, thin polycrystalline ferroelectric films of chemical composition Pb(Zr0.53Ti0.45W0.01Cd0.01)O3 and thickness df=0.5-10) x 10-6m were obtained. A disk of hot-pressed ceramics or powdered ceramic samples were used as a target. Basing on routine X-ray investigations the necessary r.f. sputtering condition for obtaining stoichiometric thin ferromagnetic films exhibiting perovskite-type structure were determined. The areas of amorphous-type thin films deposition, non-ferroelectric pyrochlore-type structure and their mixture have been observed. (author). 51 refs, 14 figs, 5 tabs

274

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2012-02-27

275

Computational analysis of pathogen-borne metallo ?-lactamases reveals discriminating structural features between B1 types  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background Genes conferring antibiotic resistance to groups of bacterial pathogens are cause for considerable concern, as many once-reliable antibiotics continue to see a reduction in efficacy. The recent discovery of the metallo ?-lactamase blaNDM-1 gene, which appears to grant antibiotic resistance to a variety of Enterobacteriaceae via a mobile plasmid, is one example of this distressing trend. The following work describes a computational analysis of pathogen-borne MBLs that focuses on the structural aspects of characterized proteins. Results Using both sequence and structural analyses, we examine residues and structural features specific to various pathogen-borne MBL types. This analysis identifies a linker region within MBL-like folds that may act as a discriminating structural feature between these proteins, and specifically resistance-associated acquirable MBLs. Recently released crystal structures of the newly emerged NDM-1 protein were aligned against related MBL structures using a variety of global and local structural alignment methods, and the overall fold conformation is examined for structural conservation. Conservation appears to be present in most areas of the protein, yet is strikingly absent within a linker region, making NDM-1 unique with respect to a linker-based classification scheme. Variability analysis of the NDM-1 crystal structure highlights unique residues in key regions as well as identifying several characteristics shared with other transferable MBLs. Conclusions A discriminating linker region identified in MBL proteins is highlighted and examined in the context of NDM-1 and primarily three other MBL types: IMP-1, VIM-2 and ccrA. The presence of an unusual linker region variant and uncommon amino acid composition at specific structurally important sites may help to explain the unusually broad kinetic profile of NDM-1 and may aid in directing research attention to areas of this protein, and possibly other MBLs, that may be targeted for inactivation or attenuation of enzymatic activity.

Cadag Eithon

2012-02-01

276

Structural and evolutionary classification of Type II restriction enzymes based on theoretical and experimental analyses.  

Science.gov (United States)

For a very long time, Type II restriction enzymes (REases) have been a paradigm of ORFans: proteins with no detectable similarity to each other and to any other protein in the database, despite common cellular and biochemical function. Crystallographic analyses published until January 2008 provided high-resolution structures for only 28 of 1637 Type II REase sequences available in the Restriction Enzyme database (REBASE). Among these structures, all but two possess catalytic domains with the common PD-(D/E)XK nuclease fold. Two structures are unrelated to the others: R.BfiI exhibits the phospholipase D (PLD) fold, while R.PabI has a new fold termed 'half-pipe'. Thus far, bioinformatic studies supported by site-directed mutagenesis have extended the number of tentatively assigned REase folds to five (now including also GIY-YIG and HNH folds identified earlier in homing endonucleases) and provided structural predictions for dozens of REase sequences without experimentally solved structures. Here, we present a comprehensive study of all Type II REase sequences available in REBASE together with their homologs detectable in the nonredundant and environmental samples databases at the NCBI. We present the summary and critical evaluation of structural assignments and predictions reported earlier, new classification of all REase sequences into families, domain architecture analysis and new predictions of three-dimensional folds. Among 289 experimentally characterized (not putative) Type II REases, whose apparently full-length sequences are available in REBASE, we assign 199 (69%) to contain the PD-(D/E)XK domain. The HNH domain is the second most common, with 24 (8%) members. When putative REases are taken into account, the fraction of PD-(D/E)XK and HNH folds changes to 48% and 30%, respectively. Fifty-six characterized (and 521 predicted) REases remain unassigned to any of the five REase folds identified so far, and may exhibit new architectures. These enzymes are proposed as the most interesting targets for structure determination by high-resolution experimental methods. Our analysis provides the first comprehensive map of sequence-structure relationships among Type II REases and will help to focus the efforts of structural and functional genomics of this large and biotechnologically important class of enzymes. PMID:18456708

Orlowski, Jerzy; Bujnicki, Janusz M

2008-06-01

277

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

Directory of Open Access Journals (Sweden)

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.

Pastan Ira

2009-01-01

278

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

Science.gov (United States)

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.

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

2009-02-01

279

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

Science.gov (United States)

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. PMID:19062128

Kodesová, Radka; Vignozzi, Nadia; Rohosková, Marcela; Hájková, Tereza; Kocárek, Martin; Pagliai, Marcello; Kozák, Josef; Sim?nek, Jirka

2009-02-16

280

High-pressure structural investigation of several zircon-type orthovanadates  

CERN Document Server

Room temperature angle-dispersive x-ray diffraction measurements on zircon-type EuVO4, LuVO4, and ScVO4 were performed up to 27 GPa. In the three compounds we found evidence of a pressure-induced structural phase transformation from zircon to a scheelite-type structure. The onset of the transition is near 8 GPa, but the transition is sluggish and the low- and high-pressure phases coexist in a pressure range of about 10 GPa. In EuVO4 and LuVO4 a second transition to a M-fergusonite-type phase was found near 21 GPa. The equations of state for the zircon and scheelite phases are also determined. Among the three studied compounds, we found that ScVO4 is less compressible than EuVO4 and LuVO4, being the most incompressible orthovanadate studied to date. The sequence of structural transitions and compressibilities are discussed in comparison with other zircon-type oxides.

Errandonea, D; Ruiz-Fuertes, J; Segura, A; Achary, S N; Tyagi, A K; 10.1103/PhysRevB.79.184104

2010-01-01

 
 
 
 
281

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2010-02-22

282

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 sucher 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.

283

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

CERN Document Server

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.

Kokabi, Alireza; Khorasani, Sina; Fardmanesh, Mehdi

2011-01-01

284

Matrix Models, Integrable Structures, and T-duality of Type 0 String Theory  

CERN Document Server

Instanton matrix models (IMM) for two dimensional string theories are obtained from the matrix quantum mechanics (MQM) of the T-dual theory. In this paper we study the connection between the IMM and MQM, which amounts to understand T-duality from the viewpoint of matrix models. We show that type 0A and type 0B matrix models perturbed by purely closed string momentum modes (or purely winding modes) have the integrable structure of Toda hierarchies, extending the well known results for c=1 string. In particular, we show that type 0A(0B) MQM perturbed by momentum modes has the same integrable structure as type 0B(0A) MQM perturbed by winding modes, which is a nontrivial check of the T-duality between the matrix models. The MQM deformed by NS-NS winding modes are used to study type 0 string in 2D black holes. We also find an intriguing connection between the IMM and the MQM via tachyon condensation. The array of alternating D-instantons and anti-D-instantons separated at the critical distance plays a key role in ...

Yin, X

2003-01-01

285

Crystal structure of the Yersinia type III secretion protein YscE  

Energy Technology Data Exchange (ETDEWEB)

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.

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

2010-12-06

286

Ground-based and spaceborn observations of the type II burst with developed fine structure  

Science.gov (United States)

The combination of two huge ground-based radio telescopes (UTR-2 and URAN-2) operated in decameter wavelengths with three spatially separated spacecrafts (SOHO, STEREO-A and STEREO-B) equipped with white light coronagraphs, UV telescopes and decameter-hectometer band radio telescopes created a unique opportunity to investigate the high energy solar transients, such as CMEs and their manifestations in radio bands - type II bursts. In this paper we made detailed analysis of the powerful and complex event occurred on 7 June 2011 consisted of Halo-CME and type II burst with rich fine structure.

Dorovskyy, V.; Melnik, V.; Konovalenko, A.; Brazhenko, A.; Rucker, H.; Stanislavskyy, A.; Panchenko, M.

2012-09-01

287

Magnetic structure of the Mn 5Si 3-type Er 5Ge 3 compound  

Science.gov (United States)

The Er 5Ge 3 compound (Mn 5Si 3-type, hP16, P6 3/mcm) at 4 K shows magnetic ordering of the antiferromagnetic type. Its magnetic structure consists of sine modulated collinear magnetic moments of Er that are parallel to the c axis (with a propagation vector k=[0 0 ±0.3]). This corresponds to the magnetic unit cell ( a a 10 c), the values of the magnetic moment of the Er atoms being, as a general formula, M z? M0 cos [2?(Z-1/4)(1-kZ)], with M0=9.2(2) ? B at 4 K.

Morozkin, A. V.; Isnard, O.; Henry, P.; Manfrinetti, P.

2006-12-01

288

Magnetic structure of the Mn5Si3-type Er5Ge3 compound  

International Nuclear Information System (INIS)

The Er5Ge3 compound (Mn5Si3-type, hP16, P63/mcm) at 4 K shows magnetic ordering of the antiferromagnetic type. Its magnetic structure consists of sine modulated collinear magnetic moments of Er that are parallel to the c axis (with a propagation vector k=[0 0 ±0.3]). This corresponds to the magnetic unit cell (a a 10c), the values of the magnetic moment of the Er atoms being, as a general formula, Mz ?M 0 cos [2?(Z-1/4)(1-kZ)], with M 0=9.2(2) ?B at 4 K

289

Structure and properties of rolled strips of microalloyed steel type 10KhSND  

International Nuclear Information System (INIS)

The paper presents an investigation of the structure and properties of 16 and 22 mm thick sheets of microalloyed steel of 10KhSND type (10Kh5SND type with a decreased content of nickel) which were rolled on a plate mill and were subjected to normalization or martempering. It is shown that the rolled stock of S390K steel, which was microalloyed with titanium, aluminium and nitrogen, after normalization features high mechanical properties and cold resistance in line with the requirements of state standard GOST 27772. Vanadium microalloying of S390K steel improves the weldability of the rolled products. 4 figs., 3 tabs

290

Structure and serology of the native polysaccharide antigen of type Ia group B Streptococcus  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The native polysaccharide antigen isolated from type Ia group B Streptococcus by using pH-controlled growth conditions and extraction procedures contains D-galactose, D-glucose, 2-acetamido-2-deoxy-D-glucose, and sialic acid in the molar ratio of 2:1:1:1. The structure of the native type Ia antigen has been elucidated; it can be represented by the following repeating unit in which all the side-chain ?-D-galactopyranose units are masked by sialic acid residues: [Formula: see text] Removal of ...

Jennings, Harold J.; Rosell, Karl-gunnar; Kasper, Dennis L.

1980-01-01

291

Generalized N?=?1 and N?=?2 structures in M-theory and type II orientifolds  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We consider M-theory and type IIA reductions to four dimensions with N?=?2 and N?=?1 supersymmetry and discuss their interconnection. Our work is based on the framework of Exceptional Generalized Geometry (EGG), which extends the tangent bundle to include all symmetries in M-theory and type II string theory, covariantizing the local U-duality group E 7(7). We describe general N?=?1 and N?=?2 reductions in terms of SU(7) and SU(6) structures on this bundle and thereby derive th...

Gran?a, Mariana; Triendl, Hagen

2013-01-01

292

Structural basis for recognition of urokinase-type plasminogen activator by plasminogen activator inhibitor-1  

DEFF Research Database (Denmark)

Plasminogen activator inhibitor-1 (PAI-1), together with its physiological target urokinase-type plasminogen activator (uPA), plays a pivotal role in fibrinolysis, cell migration, and tissue remodeling and is currently recognized as being among the most extensively validated biological prognostic factors in several cancer types. PAI-1 specifically and rapidly inhibits uPA and tissue-type PA (tPA). Despite extensive structural/functional studies on these two reactions, the underlying structural mechanism has remained unknown due to the technical difficulties of obtaining the relevant structures. Here, we report a strategy to generate a PAI-1·uPA(S195A) Michaelis complex and present its crystal structure at 2.3-Å resolution. In this structure, the PAI-1 reactive center loop serves as a bait to attract uPA onto the top of the PAI-1 molecule. The P4-P3' residues of the reactive center loop interact extensively with the uPA catalytic site, accounting for about two-thirds of the total contact area. Besides the active site, almost all uPA exosite loops, including the 37-, 60-, 97-, 147-, and 217-loops, are involved in the interaction with PAI-1. The uPA 37-loop makes an extensive interaction with PAI-1 ?-sheet B, and the 147-loop directly contacts PAI-1 ?-sheet C. Both loops are important for initial Michaelis complex formation. This study lays down a foundation for understanding the specificity of PAI-1 for uPA and tPA and provides a structural basis for further functional studies.

Lin, Zhonghui; Jiang, Longguang

2011-01-01

293

New phases RCu5Sn with the CeCu6 structure type  

International Nuclear Information System (INIS)

A series of RCu5Sn compounds, where R=La-Sm, has been synthetised. X-ray powder diffraction shows that the crystal structure of these compounds belongs to the CeCu6 structure type, but without a complete solid solution between RCu6 and RCu5Sn. The magnetic susceptibility and resistivity have been measured for CeCu5Sn and PrCu5Sn. The CeCu5Sn compound orders antiferromagnetically at 10 K, PrCu5Sn has probably a non-ordered ground state. (orig.)

294

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)

295

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)

296

On low-frequency buneman type instability in slowing-down structure  

International Nuclear Information System (INIS)

A possibility of decreasing the threshold current of Buneman instability for relativistic electron beam in slowing-down structure is investigated. On the basis of solving the dispersion equation taking into account the boundary conditions in a system of spiral waveguide with magneto dielectric it is shown analytically and numerically that due to the beam interaction with structure a low-frequency instability of Buneman type may appear independently on the ion presence. Under certain conditions the instability could loss its threshold character, the wave having a small phase velocity and a rather big increment

297

Investigation of fluid-structure interaction with various types of junction coupling  

Science.gov (United States)

In this study of water hammer with fluid-structure interaction (FSI) the main aim was the investigation of junction coupling effects. Junction coupling effects were studied in various types of discrete points, such as pumps, valves and branches. The emphasis was placed on an unrestrained pump and branch in the system, and the associated relations were derived for modelling them. Proposed relations were considered as boundary conditions for the numerical modelling which was implemented using the finite element method for the structural equations and the method of characteristics for the hydraulic equations. The results can be used by engineers in finding where junction coupling is significant.

Ahmadi, A.; Keramat, A.

2010-10-01

298

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

299

Interface effect on structural and optical properties of type II InAs/GaSb superlattices  

Science.gov (United States)

For type II InAs/GaSb superlattice (SL) structure, we reveal that, if the overall strain of the SLs is balanced to be zero, there exists a quantitative relationship between the interface (IF) materials and the SL constituent layers, which can serve as guidance on how to design the specific IF structure and on how to tune the strain. Controlled growth of a series of samples was performed to vary the strain by the IF engineering. It is found that while the photoluminescence (PL) peak position changes insignificantly with the changing strain, the PL intensity is intimately related to the strain.

Huang, Jianliang; Ma, Wenquan; Wei, Yang; Zhang, Yanhua; Cui, Kai; Shao, Jun

2014-12-01

300

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

 
 
 
 
301

R dependence of electronic structure in perovskite type structure compounds, RBRh3 (R: Sc, Y and La)  

International Nuclear Information System (INIS)

The electronic structures of perovskite type structure, RBRh3 (R: Sc, Y and La) were studied by X-ray photoelectron spectroscopy and calculation with full potential linearized augmented plane wave (FLAPW) method. As the lattice constant of the crystals increases with the atomic number of R, it can be discussed how the bond length between boron and rhodium atoms effect on the bonding character. The valence band XPS profiles of the samples are well coincided with the calculated profiles. The calculated electron density maps of the valence bands indicate the following. The charge transfer directions are from R to rhodium atoms and from boron to rhodium atoms. The bonds of R-Rh and B-Rh atoms have also covalent character. The covalency of R-Rh bond increases with the order of the atomic number of R atoms. On the other hand, the covalent bond of B-Rh decreases with the order atomic number

302

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

Directory of Open Access Journals (Sweden)

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.

O.G.Vlokh

2000-09-01

303

Peculiar reflections in diffraction patterns as indicators of structural type and quality  

Science.gov (United States)

Reflections serving as indicators of the types of packets forming crystal structures of many layered semiconductors have been revealed in diffraction patterns. It is found that the values l for the strongest reflection in series 000 l and 00 l, as well as the next to the strongest reflection in series ( h = const) and 0 kl ( k = const) for hexagonal and monoclinic structures, respectively, determine the number of polyhedral (Tand O) cation-filled layers per cell and indicate the types of packets TOT , , , , and OOE , where T and are inversely oriented tetrahedra, O is an octahedron, E is an empty interpacket layer, and E1 and E2 are partially filled (to less than 1/3) interpacket layers.

Kyazumov, M. G.

2014-09-01

304

A Comparison and Selection on Basic Type of Searching Algorithm in Data Structure?  

Directory of Open Access Journals (Sweden)

Full Text Available A lot of problems in different practical fields of Computer Science, Database Management System, Networks, Data Mining and Artificial intelligence. Searching is common fundamental operation and solve to searching problem in a different formats of these field. This research paper are presents the basic type of searching algorithms of data structure like linear search, binary search, and hash search. We have try to cover some technical aspects to this searching algorithm. This research is provides a detailed study of searching algorithms working process, select on Searching Algorithm according To Problem and compares them on the basis of different parameters like total number of comparison, type of data Structure, time complexity and space complexity.

Kamlesh Kumar Pandey

2014-07-01

305

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

Energy Technology Data Exchange (ETDEWEB)

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.

Bell, Christopher

2011-08-19

306

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

DEFF Research Database (Denmark)

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.

Wang, Kaituo; Sitsel, Oleg

2014-01-01

307

Structure and mechanism of Zn(2+)-transporting P-type ATPases  

DEFF Research Database (Denmark)

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.

Wang, Kaituo; Sitsel, Oleg

2014-01-01

308

Recent advances in the structural and molecular biology of type IV secretion systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Bacteria use type IV secretion (T4S) systems to deliver DNA and protein substrates to a diverse range of prokaryotic and eukaryotic target cells. T4S systems have great impact on human health, as they are a major source of antibiotic resistance spread among bacteria and are central to infection processes of many pathogens. Therefore, deciphering the structure and underlying translocation mechanism of T4S systems is crucial to facilitate development of new drugs. The last five years have witne...

Trokter, Martina; Felisberto-rodrigues, Catarina; Christie, P. J.; Waksman, Gabriel

2014-01-01

309

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

Science.gov (United States)

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. PMID:25132545

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

2014-10-23

310

Nonmetric Multidimensional Scaling Corrects for Population Structure in Association Mapping With Different Sample Types  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Recent research has developed various promising methods to control for population structure in genomewide association mapping of complex traits, but systematic examination of how well these methods perform under different genetic scenarios is still lacking. Appropriate methods for controlling genetic relationships among individuals need to balance the concern of false positives and statistical power, which can vary for different association sample types. We used a series of simulated samples ...

Zhu, Chengsong; Yu, Jianming

2009-01-01

311

Peptoids with aliphatic sidechains as helical structures without hydrogen bonds and collagen/ inverse-collagen type structures  

Directory of Open Access Journals (Sweden)

Full Text Available Aliphatic homo-polypeptoids of NAla, NVal, NIle and NLeu both in the presence and absence of protecting groups adopt helical structures without hydrogen bonds with ?, ? values of ~ 0, ± 90° with trans amide bonds. These structures are stabilized by carbonyl-carbonyl interactions and characterized by ~ 3.16 residues per turn with a pitch of ~ 6.13 Å. It has been shown that like polyvaline and polyleucine peptides, poly-peptoids can also be exploited for the construction of potential surfactant like molecules by incorporating charged amino acid residues at the N terminal. A single-handed template with ?, ? values of ~ 0, 90° can be attained by incorporating L-leu or L-val at the C-terminal of poly-NIle. Analysis of the simulation results in water as a function of time reveals that the opening of helical structures without hydrogen bonds takes place at sub-picosecond time scale starting from the N-terminal. This leads to the formation of collagen or inverse-collagen type structures (?, ? ~ -60, 145° and 60, -145° respectively stabilized by interactions of water molecules with the backbone carbonyl groups.

Fateh S. Nandel

2011-02-01

312

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2012-01-13

313

Lanthanide diruthenium(II,III) compounds showing layered and PtS-type open framework structures.  

Science.gov (United States)

Two types of lanthanide diruthenium phosphonate compounds, based on the mixed-valent metal-metal bonded paddlewheel core of Ru(2)(hedp)(2)(3-) [hedp = 1-hydroxyethylidenediphosphonate, CH(3)C(OH)(PO(3))(2)], have been prepared with the formulas Ln(H(2)O)4[Ru(2)(hedp)(2)(H(2)O)2].5.5H(2)O (1.Ln, Ln = La, Ce) and Ln(H(2)O)4[Ru(2)(hedp)(2)(H(2)O)(2)].8H(2)O (2.Ln, Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er). In both types, each Ru(2)(hedp)2(H2O)23- unit is linked by four Ln(3+)ions through four phosphonate oxygen (OP) atoms and vice versa. The geometries of the {LnO(P4)} group, however, are different in the two cases. In 1.Ln, the geometry of {LnO(P4)} is closer to a distorted plane, and thus a square-grid layer structure is found. In 2.Ln, the geometry of {LnO(P4)} is better described as a distorted tetrahedron; hence, a unique PtS-type open-framework structure is observed. The channels generated in structures 2.Ln are filled with water aggregates with extensive hydrogen-bond interactions. The magnetic and electrochemical properties are also investigated. PMID:17850070

Liu, Bin; Li, Bao-Long; Li, Yi-Zhi; Chen, Yu; Bao, Song-Song; Zheng, Li-Min

2007-10-15

314

Relations between the zinc-blende and the NaCl structure type.  

Science.gov (United States)

A new model for the transformation from the zinc-blende to the NaCl type is developed on the basis of the deformation of a 4-connected heterogeneous sphere packing in space group P3(2). The geometrical features of this transition are discussed by investigating the analogous deformations of a 4-connected homogeneous sphere packing in the supergroup P3(2)21 of P3(2). In this space group, the atomic arrangement corresponds to a diamond configuration. During the phase transition, it is deformed under preservation of all sphere contacts until a cubic primitive lattice is reached, the analogue of the NaCl arrangement formed by like atoms. The intermediate structure that occurs between the zinc-blende and the NaCl type is compared with the cinnabar type. PMID:12714779

Sowa, H

2003-05-01

315

Problem solving with pentagons: Tsai-type quasicrystal as a structural response to chemical pressure.  

Science.gov (United States)

Even after significant advances in the structural characterization of quasicrystals--phases whose diffraction patterns combine the sharp peaks normally associated with lattice periodicity and rotational symmetries antithetical to such periodicity--this new form of long-range order remains enigmatic. Here, we present DFT-chemical pressure calculations on the Tsai-type quasicrystal approximant CaCd6, which reveal how its icosahedral clusters can be traced to simple CaCu5-type (hP6) intermetallics. The results indicate that the Tsai-type clusters emerge from an atomic-size-driven transformation from planar arrangements to spherical clusters, recalling the relationship between graphene and C60. PMID:24161006

Berns, Veronica M; Fredrickson, Daniel C

2013-11-18

316

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

DEFF Research Database (Denmark)

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.

Yan, Ning; Naulin, Volker

317

The Effect of Impeller Type on Floc Size and Structure during Shear-Induced Flocculation  

Science.gov (United States)

The effect of impeller type and shear rate on the evolution of floc size and structure during shear-induced flocculation of polystyrene particles with aluminum sulfate is investigated by image analysis. One radial flow (six-blade Rushton turbine) and two axial flow (three-blade fluid foil, four-blade 45° pitch) impeller configurations are examined. The steady state average floc size is shown to depend on the frequency of recirculation to the impeller zone and its characteristic velocity gradient. The concepts of fractal geometry are used to characterize the floc structure. For all impellers, the two-dimensional floc fractal dimension, Dpf, increases during floc growth, indicating formation of more open structures. Later on, Dpf levels off at a steady state value as breakage becomes significant and the floc size distribution approaches steady state. The shear rate does not affect the steady state Dpf of the flocs within experimental uncertainty. PMID:8954644

Spicer; Keller; Pratsinis

1996-12-01

318

Development of a new benzophenone-diketopiperazine-type potent antimicrotubule agent possessing a 2-pyridine structure.  

Science.gov (United States)

A new benzophenone-diketopiperazine-type potent antimicrotubule agent was developed by modifying the structure of the clinical candidate plinabulin (1). Although the right-hand imidazole ring with a branched alkyl chain at the 5-position in 1 was critical for the potency of the antimicrotubule activity, we successfully substituted this moiety with a simpler 2-pyridyl structure by converting the left-hand ring from a phenyl to a benzophenone structure without decreasing the potency. The resultant compound 6b (KPU-300) exhibited a potent cytotoxicity, with an IC50 value of 7.0 nM against HT-29 cells, by strongly binding to tubulin (K d = 1.3 ?M) and inducing microtubule depolymerization. PMID:25313318

Hayashi, Yoshiki; Takeno, Haruka; Chinen, Takumi; Muguruma, Kyohei; Okuyama, Kohei; Taguchi, Akihiro; Takayama, Kentaro; Yakushiji, Fumika; Miura, Masahiko; Usui, Takeo; Hayashi, Yoshio

2014-10-01

319

Self-assembly nano-structure of type I collagen adsorbed on Gemini surfactant LB monolayers.  

Science.gov (United States)

The self-assembly nano-structures of type I collagen adsorbed on anionic Gemini surfactant LB monolayer were observed by using atomic force microscopy (AFM) images. It was found that the adsorption behavior and self-assembly structure of collagen could be controlled by the concentration of the collagen solution, adsorption interval and the properties of substrates. With the increase of the adsorption interval and concentration of collagen, the strands size of collagen changed. The self-assembly structures of collagen were also influenced by the interaction between collagen molecules and Gemini surfactant monolayer substrates. Finally, the adsorption behaviors of collagen molecules on cationic Gemini monolayer were compared with those on anionic Gemini monolayer. PMID:19157808

Xu, Shouhong; Liu, Aiping; Chen, Qibin; Lv, Mingyu; Yonese, Masakastu; Liu, Honglai

2009-04-01

320

Elastic stability and electronic structure of pyrite type PtN2: Ahard semiconductor  

Energy Technology Data Exchange (ETDEWEB)

The elastic properties and electronic structure of PtN2 withthe pyrite structure (PtN2(C2)) were studied with first-principlescalculations. The crystal structure is demonstrated to be elasticallystable with a lower energy than the metastable fluorite structureproposed before. The calculated shear modulus of 214 GPa suggests thatPtN2(C2) is harder than some well known hard materials such as TiN andSiC. The high elastic moduli are attributed to a stacking ofcorner-shared PtN6 octahedra bonded by strong N-N covalent bonding. Incontrast to the metallic fluorite-type phase, PtN2(C2) is semiconductingwith an indirect band gap.

Yu, Rong; Zhan, Qian; Zhang, Xiao-Feng

2006-08-29

 
 
 
 
321

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

322

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

CERN Document Server

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.

Gorban, A N; Zinovyev, A Yu

2011-01-01

323

Cation states of iron in complicated oxides with various derivative type of structure from perovskite  

International Nuclear Information System (INIS)

cy' of oxygen in recalculation on an elementary cell of ideal perovskite (formula unit ABX3, where A, B -cations, X - anion): 1) ABX3 (OF); 2) A5B5X15-2=5xABX2.6 (4-1-5); 3) A8B8X24-4 = 8xABX2.5 (8-8-20); 4) A3B3X9-2 = 3xABX2.3 (1-2-3). The carried out studies show: 1) magnetic ordering of iron cations (at room temperature) in all researched oxides with the structures derivative from perovskite arises only in octahedral positions; It can be explained by the fact, that the increase in oxygen deficiency results in break of chains Fe-O-Fe through which there is an exchange interaction; 2) in OF and 4-1-5 oxides iron is only as Fe3+ in oxygen-deficient compounds of type 8-8-20 and 1-2-3 - in mixed valent state Fe3+ -Fe4+; i.e. to growth of deficiency of structural anions there is a displacement of a valent state of iron ions from '+3' to '+4'; 3) in OF Fe- and Mo- cations are statistically distributed on octahedral sites of structure; in compounds of type 4-1-5 and 8-8-20, iron placed in octahedral and pyramidal positions both independently of iron concentration; in oxides of type 1-2-3 iron substitutes copper only in positions Cu, having various oxygen coordination: from a square plane up to an octahedron; the majority iron atoms in perovskite-related structures are placed in octahedral positions, further on 'population' square pyramids and squares plane follow; it is explained following: at first place the iron ions prefer octahedral coordination, at second - in case of oxygen-deficient structures first two coordinations are resulted not only by substitution of copper in these positions, but also by attraction of additional oxygen in the environment; 4) the increase of oxygen deficiency results in downturn of symmetry of structural polyhedrons: the most symmetric polyhedrons in OF, further follow compounds of type 4-1-5, 8-8-20 and 1-2-3. The present work has been performed with the support of the grants of Tatarstan Academy of Sciences No. 06-6.1-142, CRDF (REC-007), Scientific School-1708.2003.2

324

Data with hierarchical structure: impact of intraclass correlation and sample size on Type-I error  

Directory of Open Access Journals (Sweden)

Full Text Available 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.

SerbanCMusca

2011-04-01

325

THE SLACS SURVEY. VIII. THE RELATION BETWEEN ENVIRONMENT AND INTERNAL STRUCTURE OF EARLY-TYPE GALAXIES  

International Nuclear Information System (INIS)

We study the relation between the internal structure of early-type galaxies and their environment using 70 strong gravitational lenses from the SLACS Survey. The Sloan Digital Sky Survey (SDSS) database is used to determine two measures of overdensity of galaxies around each lens-the projected number density of galaxies inside the tenth nearest neighbor (?10) and within a cone of radius one h-1 Mpc (D 1). Our main results are as follows. (1) The average overdensity is somewhat larger than unity, consistent with lenses preferring overdense environments as expected for massive early-type galaxies (12/70 lenses are in known groups/clusters). (2) The distribution of overdensities is indistinguishable from that of 'twin' nonlens galaxies selected from SDSS to have the same redshift and stellar velocity dispersion ?*. Thus, within our errors, lens galaxies are an unbiased population, and the SLACS results can be generalized to the overall population of early-type galaxies. (3) Typical contributions from external mass distribution are no more than a few percent in local mass density, reaching 10-20% (?0.05-0.10 external convergence) only in the most extreme overdensities. (4) No significant correlation between overdensity and slope of the mass-density profile of the lens galaxies is found. (5) Satellite galaxies (those with a more luminous companion) have marginally steeper mass-density profiles (as quantified by f SIESIE = ?*/?SIE = 1.12 ± 0.05 versus 1.01 ± 0.01) and smaller dynamically normalized mass enclosed within the Einstein radius (?log M Ein/M dim differs by -0.09 ± 0.03 dex) than central galaxies (those without). This result suggests that tidal stripping may affect the mass structure of early-type galaxies down to kpc scales probed by strong lensing, when they fall into larger structures.

326

Functional and Structural Analysis of Five Mutations Identified in Methylmalonic Aciduria cbIB Type  

Science.gov (United States)

ATP cob(I)alamin adenosyltransferase (ATR, E.C.2.5.1.17) converts reduced cob(I)alamin to the adenosylcobalamin cofactor. Mutations in the MMAB gene encoding ATR are responsible for the cblB type methylmalonic aciduria. Here we report the functional analysis of five cblB mutations to determine the underlying molecular basis of the dysfunction. The transcriptional profile along with minigenes analysis revealed that c.584G>A, c.349-1G>C and c.290G>A affect the splicing process. Wild-type ATR and the p.I96T (c.287T>C) and p.R191W (c.571C>T) mutant proteins were expressed in a prokaryote and a eukaryotic expression systems. The p.I96T protein was enzymatically active with a KM for ATP and KD for cob(I)alamin similar to wild-type enzyme, but exhibited a 40% reduction in specific activity. Both p.I96T and p.R191W mutant proteins are less stable than the wild-type protein, with increased stability when expressed under permissive folding conditions. Analysis of the oligomeric state of both mutants showed a structural defect for p.I96T and also a significant impact on the amount of recovered mutant protein that was more pronounced for p.R191W that, along with the structural analysis, suggest they might be misfolded. These results could serve as a basis for the implementation of pharmacological therapies aimed at increasing the residual activity of this type of mutations. PMID:20556797

Jorge-Finnigan, Ana; Aguado, Cristina; Sánchez-Alcudia, Rocio; Abia, David; Richard, Eva; Merinero, Begoña; Gámez, Alejandra; Banerjee, Ruma; Desviat, Lourdes R.; Ugarte, Magdalena; Pérez, Belen

2010-01-01

327

Magnetic properties of HoCoMn compounds with the 2:17-type structure  

International Nuclear Information System (INIS)

The structural and magnetic properties of Ho2Co17-xMnx (x=0-4) compounds have been investigated by means of X-ray diffraction (XRD) and magnetic measurements. Powder XRD patterns show that the compounds with x=1, 3, 4 are single phase with rhombohedral Th2Zn17-type structure while the compounds with x=0, 2 are a mixture of rhombohedral Th2Zn17-type phase and a trace of the hexagonal Th2Ni17-type phase. The substitution of Mn for Co leads to a linear increase in lattice constants a, c and unit cell volume v. The Curie temperature TC decreases linearly with increasing Mn substitution. The saturation moment firstly increases with increasing Mn substitution for x?2, and then decreases. XRD measurement on magnetically aligned samples demonstrates that x=1 exhibits an easy-cone type of anisotropy at room temperature, x=2-4 exhibit an easy-axis type of anisotropy at room temperature. The spin-reorientation transitions are found in the M-T curves for all samples. The magnetic phase diagram is given. The magnetocrystalline anisotropy constants K1 and K2 are deduced from fitting the reversible recoil curve in the hard direction by a modified Sucksmith-Thompson plot. K1 increases with increasing Mn content and K2 is comparable to K1 in amplitude. The magnetocrystalline anisotropy field ?0HA iropy field ?0HA is found first to increase and then decrease with increasing Mn concentration, attaining a maximum value of 3.7 T at x=3

328

Unique failure behavior of metal/composite aircraft structural components under crash type loads  

Science.gov (United States)

Failure behavior results are presented on some of the crash dynamics research conducted with concepts of aircraft elements and substructure which have not necessarily been designed or optimized for energy absorption or crash loading considerations. To achieve desired new designs which incorporate improved energy absorption capabilities often requires an understanding of how more conventional designs behave under crash type loadings. Experimental and analytical data are presented which indicate some general trends in the failure behavior of a class of composite structures which include individual fuselage frames, skeleton subfloors with stringers and floor beams but without skin covering, and subfloors with skin added to the frame-stringer arrangement. Although the behavior is complex, a strong similarity in the static/dynamic failure behavior among these structures is illustrated through photographs of the experimental results and through analytical data of generic composite structural models. It is believed that the thread of similarity in behavior is telling the designer and dynamists a great deal about what to expect in the crash behavior of these structures and can guide designs for improving the energy absorption and crash behavior of such structures.

Carden, Huey D.

1990-01-01

329

A structure damage detection method based on wavelet analysis and type-2 fuzzy logic system  

Science.gov (United States)

In this paper, a damage detection method based on a combination of wavelet analysis and an interval type-2 fuzzy logic system (IT-2FLS) is proposed. Firstly, synthesizing IT-2FLSs as a data-driven model is proposed. The structure is then divided into elements and excited to be vibrated to measure vibration signal. Average quantity signal of wavelet transform coefficient (AQWTC) of vibration signal with a used-scale-sheet is established. The IT-2FLS is utilized to identify the structure at its undamaged time via AQWTC signal. At each surveying time, AQWTC at each element is calculated to estimate difference of corresponding AQWTCs between two cases: undamaged status and the status at the checked time. By applying the AQWTC's contrast at two these times, a damage coefficient is described which is used to estimate status of the structure. Besides, in order to predict structure's status, the time-series prediction using the IT-2FLS and the calculated damage coefficient are also presented. The effectiveness of the proposed method is demonstrated by experiment via data sources measured from dynamic response of a real structure.

Nguyen, Sy Dzung; Tran, Quang Thinh; Ngo, Kieu Nhi; Do, Xuan Phu; Choi, Seung-Bok

2014-03-01

330

Crystal structure of alluaudite-type Na4Co(MoO4)3.  

Science.gov (United States)

The title compound, tetra-sodium cobalt(II) tris-[molyb-date(IV)], was prepared by solid-state reactions. The structure is isotypic with Na3In2(AsO4)3 and Na3In2(PO4)3. The main structural feature is the presence of infinite chains of edge-sharing X 2O10 (X = Co/Na) dimers, which are linked by MoO4 tetra-hedra, forming a three-dimensional framework enclosing two types of hexa-gonal tunnels in which Na(+) cations reside. In this alluaudite structure, Co and Na atoms are located at the same general site with occupancies of 0.503?(5) and 0.497?(6), respectively. The other three Na and one of the two Mo atoms lie on special positions (site symmetries 2, -1, 2 and 2, respectively). The structure is compared with similar structures and other members of alluaudite family. PMID:25309171

Nasri, Rawia; Fakhar Bourguiba, Noura; Zid, Mohamed Faouzi; Driss, Ahmed

2014-09-01

331

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

CERN Document Server

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.

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

2012-01-01

332

Dynamic buckling test using 1/10 scale model of pool type LMFBR structure  

International Nuclear Information System (INIS)

In Japan, one of the critical issues in the seismic design of a pool type LMFBR is considered to be the evaluation of the buckling strength for a main vessel. In the technical assessment studies on the pool type LMFBR, shear buckling characteristics of the main vessel, as a simple cylindrical shell, were investigated through experiments and analyses. However, in the actual LMFBR structure, not only shape and material properties in the main vessel, but also interaction effects of internal components and fluid in the main vessel can significantly affect the dynamic buckling behavior of the main vessel. The objectives of this study are to evaluate the dynamic buckling strength for the main vessel and to investigate the effects of internal components and fluid on the buckling responses of the pool type LMFBR by using a similar scale model for a FBR structure. This paper presents experimental and analytical results for the preliminary dynamic buckling tests using the feasibility study 1/10 scale model in the above mentioned first step study

333

Spectral Structures and Their Generation Mechanisms for Solar Radio Type-I Bursts  

CERN Document Server

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 AMATEAS 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 were no similarity shapes in 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 non-thermal electrons is modulated in the subsequent stages of the genera...

Iwai, Kazumasa; Masuda, Satoshi; Tsuchiya, Fuminori; Morioka, Akira; Misawa, Hiroaki

2014-01-01

334

Structure of the Type IVa Major Pilin from the Electrically Conductive Bacterial Nanowires of Geobacter sulfurreducens*  

Science.gov (United States)

Several species of ? proteobacteria are capable of reducing insoluble metal oxides as well as other extracellular electron acceptors. These bacteria play a critical role in the cycling of minerals in subsurface environments, sediments, and groundwater. In some species of bacteria such as Geobacter sulfurreducens, the transport of electrons is proposed to be facilitated by filamentous fibers that are referred to as bacterial nanowires. These nanowires are polymeric assemblies of proteins belonging to the type IVa family of pilin proteins and are mainly comprised of one subunit protein, PilA. Here, we report the high resolution solution NMR structure of the PilA protein from G. sulfurreducens determined in detergent micelles. The protein is >85% ?-helical and exhibits similar architecture to the N-terminal regions of other non-conductive type IVa pilins. The detergent micelle interacts with the first 21 amino acids of the protein, indicating that this region likely associates with the bacterial inner membrane prior to fiber formation. A model of the G. sulfurreducens pilus fiber is proposed based on docking of this structure into the fiber model of the type IVa pilin from Neisseria gonorrhoeae. This model provides insight into the organization of aromatic amino acids that are important for electrical conduction. PMID:23965997

Reardon, Patrick N.; Mueller, Karl T.

2013-01-01

335

Physcomitrella HMGA-type proteins display structural differences compared to their higher plant counterparts  

International Nuclear Information System (INIS)

High mobility group (HMG) proteins of the HMGA family are chromatin-associated proteins that act as architectural factors in nucleoprotein structures involved in gene transcription. To date, HMGA-type proteins have been studied in various higher plant species, but not in lower plants. We have identified two HMGA-type proteins, HMGA1 and HMGA2, encoded in the genome of the moss model Physcomitrella patens. Compared to higher plant HMGA proteins, the two Physcomitrella proteins display some structural differences. Thus, the moss HMGA proteins have six (rather than four) AT-hook DNA-binding motifs and their N-terminal domain lacks similarity to linker histone H1. HMGA2 is expressed in moss protonema and it localises to the cell nucleus. Typical of HMGA proteins, HMGA2 interacts preferentially with A/T-rich DNA, when compared with G/C-rich DNA. In cotransformation assays in Physcomitrella protoplasts, HMGA2 stimulated reporter gene expression. In summary, our data show that functional HMGA-type proteins occur in Physcomitrella

336

Structure of the type IVa major pilin from the electrically conductive bacterial nanowires of Geobacter sulfurreducens.  

Science.gov (United States)

Several species of ? proteobacteria are capable of reducing insoluble metal oxides as well as other extracellular electron acceptors. These bacteria play a critical role in the cycling of minerals in subsurface environments, sediments, and groundwater. In some species of bacteria such as Geobacter sulfurreducens, the transport of electrons is proposed to be facilitated by filamentous fibers that are referred to as bacterial nanowires. These nanowires are polymeric assemblies of proteins belonging to the type IVa family of pilin proteins and are mainly comprised of one subunit protein, PilA. Here, we report the high resolution solution NMR structure of the PilA protein from G. sulfurreducens determined in detergent micelles. The protein is >85% ?-helical and exhibits similar architecture to the N-terminal regions of other non-conductive type IVa pilins. The detergent micelle interacts with the first 21 amino acids of the protein, indicating that this region likely associates with the bacterial inner membrane prior to fiber formation. A model of the G. sulfurreducens pilus fiber is proposed based on docking of this structure into the fiber model of the type IVa pilin from Neisseria gonorrhoeae. This model provides insight into the organization of aromatic amino acids that are important for electrical conduction. PMID:23965997

Reardon, Patrick N; Mueller, Karl T

2013-10-11

337

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

DEFF Research Database (Denmark)

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.

Shahpiri, Azar; Svensson, Birte

2009-01-01

338

Generalized N = 1 and N = 2 structures in M-theory and type II orientifolds  

Science.gov (United States)

We consider M-theory and type IIA reductions to four dimensions with N = 2 and N = 1 supersymmetry and discuss their interconnection. Our work is based on the framework of Exceptional Generalized Geometry (EGG), which extends the tangent bundle to include all symmetries in M-theory and type II string theory, covariantizing the local U-duality group E 7(7). We describe general N = 1 and N = 2 reductions in terms of SU(7) and SU(6) structures on this bundle and thereby derive the effective four-dimensional N = 1 and N = 2 couplings, in particular we compute the Kähler and hyper-Kähler potentials as well as the triplet of Killing prepotentials (or the superpotential in the N = 1 case). These structures and couplings can be described in terms of forms on an eight-dimensional tangent space where SL(8) ? E 7 acts, which might indicate a description in terms of an eight-dimensional internal space, similar to F-theory. We finally discuss an orbifold action in M-theory and its reduction to O6 orientifolds, and show how the projection on the N = 2 structures selects the N = 1 ones. We briefly comment on new orientifold projections, U-dual to the standard ones.

Graña, Mariana; Triendl, Hagen

2013-03-01

339

Solar decimetric type III bursts in semi-closed magnetic field structures  

Science.gov (United States)

Aims: We investigate statistically seventeen groups of solar type III bursts, observed in the frequency range 950-2500 MHz using the Brazilian Solar Spectroscope (BSS) during the period 1999-2002. Methods: Using specially-developed Interactive Data Language (IDL) software called BSSView, the spectral characteristic properties of the bursts were investigated. For illustration a semi-closed magnetic field structure with trapped electron beams was modelled using the particle-in-cell model. Results: Most of the type III bursts studied in this paper have starting frequencies in the range 1100-1400 MHz and their average bandwidth, half-power duration, and interval between adjacent bursts are 116 ± 59 MHz, 108 ± 41 ms, and 647 ± 643 ms, respectively. The number of bursts with negative frequency drift, which is on average -914 ± 684 MHz s-1, is greater than the number with positive frequency drift, which is on average +807 ± 675 MHz s-1. The type III bursts have power-law distribution function for their half-power duration H(f_start) = 4.79 × 108~f_start-2.145± 0.015, bandwidth B_1(f_start) = 1.95 × 10^7~f_start-1.697± 0.022 and B_2(f_start) = 7.07 × 10^5~f_start-1.154± 0.015, and frequency drift D(f_start) = 0.43~f_start1.040± 0.031. Most of the groups of type III bursts were also found to exhibit either positive or negative group frequency drifts of on average +53 ± 38 MHz s-1 and -46 ± 42 MHz s-1, respectively. The detailed statistical analysis suggests that in the frequency range studied there are two categories of type III bursts, the average parameters of which we provide in brackets for each type: a) numerous narrowband bursts (bandwidth ~100 MHz) with small frequency drift (~±500 MHz s-1) in groups with visible group drift (~±50 MHz s-1) and b) less numerous broader band bursts (bandwidth 171 MHz) with higher frequency drift (~±1800 MHz s-1) in groups without group drift. The statistics of the parameters of these drifting groups are presented for the first time. The drifting groups of type III bursts are interpreted as due to electron beams trapped in moving plasmoids, which are semi-closed magnetic field structures.

Mészárosová, H.; Karlický, M.; Sawant, H. S.; Fernandes, F. C. R.; Cecatto, J. R.; de Andrade, M. C.

2008-06-01

340

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  

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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.

Elahi-Moghaddam Zohreh

2013-01-01

 
 
 
 
341

Structure and stability of Ba-Cu-Ge type-I clathrates  

International Nuclear Information System (INIS)

We have prepared samples of nominal type Ba8CuxGe46-x by induction melting and solid state reaction. Analysis shows that these materials form type-I clathrates, with a copper content between x = 4.9 and 5.3, nearly independent of the starting composition. We used x-ray powder diffraction and single-crystal electron diffraction to confirm the cubic type-I clathrate structure, while electron microprobe measurements confirmed the stability of the x ? 5 composition. This result differs from the corresponding Ag and Au clathrates and was not known previously due perhaps to the similar Cu and Ge form factors in x-ray diffraction. The observed composition adheres very tightly to a valence-counting scheme, in agreement with a Zintl-type stability mechanism. This implies a gap in the electronic density of states, also in contrast to the metallic behaviour of the Au and Ag analogues. Magnetization measurements showed a large diamagnetic response in the Ba-Cu-Ge clathrate. This behaviour is consistent with semiconducting or semimetallic behaviour and is similar to that of a number of intermetallic semiconductors

342

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

Science.gov (United States)

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.

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

2013-10-01

343

Designing p-type semiconductor-metal hybrid structures for improved photocatalysis.  

Science.gov (United States)

A practical strategy is proposed to facilitate the migration of holes in semiconductor (the low rate of which limits photocatalytic efficiency) by taking advantage of the Schottky barrier between p-type semiconductor and metal. A high work function is found to serve as an important selection rule for building such desirable Schottky junction between semiconductor surface facets and metal. The intrinsic charge spatial distribution has to be taken into account when selecting the facets, as it results in accumulation of photoexcited electrons and holes on certain semiconductor facets. Importantly, the facets have a high work function, the same characteristic required for the formation of Schottky junction in a p-type semiconductor-metal hybrid structure. As a result, the semiconductor crystals in the hybrid design may be better enclosed by single facets with high work function, so as to synergize the two effects: Schottky barrier versus charge spatial separation. PMID:24700571

Wang, Lili; Ge, Jing; Wang, Ailun; Deng, Mingsen; Wang, Xijun; Bai, Song; Li, Rui; Jiang, Jun; Zhang, Qun; Luo, Yi; Xiong, Yujie

2014-05-12

344

Recent Observations and Structural Analysis of Surge-Type Glaciers in the Glacier Bay Area  

Science.gov (United States)

The Chugach-St.-Elias Mountains in North America hold the largest non-polar connected glaciated area of the world. Most of its larger glaciers are surge-type glaciers. In the summer of 2003, we collected aerial photographic and GPS data over numerous glaciers in the eastern St. Elias Mountains, including the Glacier Bay area. Observed glaciers include Davidson, Casement, McBride, Riggs, Cushing, Carroll, Rendu, Tsirku, Grand Pacific, Melbern, Ferris, Margerie, Johns Hopkins, Lamplugh, Reid, Burroughs, Morse, Muir and Willard Glaciers, of which Carroll, Rendu, Ferris, Grand Pacific, Johns Hopkins and Margerie Glaciers are surge-type glaciers. Our approach utilizes a quantitative analysis of surface patterns, following the principles of structural geology for the analysis of brittle-deformation patterns (manifested in crevasses) and ductile deformation patterns (visible in folded moraines). First results will be presented.

Mayer, H.; Herzfeld, U. C.

2003-12-01

345

The structure of a lipid-water lamellar phase containing two types of lipid monolayers  

International Nuclear Information System (INIS)

One lamellar phase, observed in the mitochondrial lipids-water system at low temperature (ca 253 K) and at low water content (ca 15%), contains four lipid monolayers in its unit cell, two of type ? and two of type ?. Previous X-ray scattering studies of this phase led to an ambiguity: the phase could contain either two homogeneous bilayers, one ? and one ?, or two mixed bilayers, each formed by an ? and a ? monolayer. A solution to this problem was sought in a neutron scattering study as a function of the D2O/H2O ratio. Because of limited resolution, straightforward analysis of the neutron scattering data leads also to ambiguous results. Using a more sophisticated analysis based upon the zeroth- and second-order moments of the Patterson peaks relevant to the exchangeable components, it is shown that the weight of the evidence is in favour of a structure containing mixed bilayers. (Auth.)

346

Preparation, crystal structure and photoluminescence of garnet-type calcium tin titanium aluminates  

International Nuclear Information System (INIS)

n. Display Omitted Research highlights: ? New garnet-type solid solutions were found in the CaO-Al2O3-TiO2-SnO2 system. ? Single crystals of Ca3Sn2.2Ti0.8Al2O12 were obtained by the self-flux method. ? Solid solutions with nominal compositions Ca3Sn3-xTixAl2O12 (x=0.6-1.4) were prepared by solid state reaction at 1370 oC. ? Sn4+ and Ti4+ partially occupy both tetrahedral and octahedral sites, respectively, in the garnet-type structure. ? Ca3Sn3-xTixAl2O12 solid solutions emitted blue-white light with a peak wavelength at 465 nm under UV irradiation.

347

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

Science.gov (United States)

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

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

348

Li-ion diffusion kinetics in LiCoPO{sub 4} thin films deposited on NASICON-type glass ceramic electrolytes by magnetron sputtering  

Energy Technology Data Exchange (ETDEWEB)

LiCoPO{sub 4} thin films were deposited on Li{sub 1+x+y}Al{sub x}Ti{sub 2-x}Si{sub y}P{sub 3-y}O{sub 12} (LATSP) solid electrolyte by radio frequency magnetron sputtering and were characterized by X-ray diffraction and scanning electron microscope. The films show a (1 1 1) preferred orientation upon annealing and are chemically stable with LATSP up to 600 C in air. An all-solid-state Li/PEO{sub 18}-Li(CF{sub 3}SO{sub 2}){sub 2}N/LATSP/LiCoPO{sub 4}/Au cell was fabricated to investigate the electrochemical performance and Li-ion chemical diffusion coefficients, D{sub Li}, of the LiCoPO{sub 4} thin films. The potential dependence of D{sub Li} values of the LiCoPO{sub 4} thin film was investigated by potentiostatic intermittent titration technique and was compared with those of the LiFePO{sub 4} thin film. These results showed that the intercalation mechanism of Li-ion in LiCoPO{sub 4} is different from that in LiFePO{sub 4}. (author)

Xie, J.; Imanishi, N.; Zhang, T.; Hirano, A.; Takeda, Y.; Yamamoto, O. [Department of Chemistry, Faculty of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8507 (Japan)

2009-07-15

349

Crystal structure of human CDK4 in complex with a D-type cyclin  

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The cyclin D1–cyclin-dependent kinase 4 (CDK4) complex is a key regulator of the transition through the G1 phase of the cell cycle. Among the cyclin/CDKs, CDK4 and cyclin D1 are the most frequently activated by somatic genetic alterations in multiple tumor types. Thus, aberrant regulation of the CDK4/cyclin D1 pathway plays an essential role in oncogenesis; hence, CDK4 is a genetically validated therapeutic target. Although X-ray crystallographic structures have been determined for various ...

Day, Philip J.; Cleasby, Anne; Tickle, Ian J.; O Reilly, Marc; Coyle, Joe E.; Holding, Finn P.; Mcmenamin, Rachel L.; Yon, Jeff; Chopra, Rajiv; Lengauer, Christoph; Jhoti, Harren

2009-01-01

350

Structure fragmentation in Fe-based alloys by means of cyclic martensitic transformations of different types.  

Science.gov (United States)

The effect of martensite transformations of different types on the misorientation of austenite crystalline lattice, which characterizes the degree of structure fragmentation, was investigated for Fe-Ni and Fe-Mn alloys. As a result of multiple face-centered cubic (f.c.c.)-body-centered cubic (b.c.c.)-f.c.c. transformations, an austenite single-crystalline specimen is transformed in a polycrystalline one due to progressive fragmentation. It was shown that the degree of fragmentation depends on the magnitude of volume change and the density of dislocations generated on martensitic transformations. PMID:24565160

Bondar, Volodimir I; Danilchenko, Vitalij Ie; Dzevin, Ievgenij M

2014-01-01

351

Structural stability analysis of 2D Wigner crystal with Gaussian type positive background  

International Nuclear Information System (INIS)

The non-magnetic phase of 2D Wigner electron crystal is investigated using a localized representation for the electrons. The ground state energies of non-magnetic phase of 2D Wigner electron crystal with Gaussian type positive background are computed in the range from rs=5 to 100. The role of correlation energy is suitably taken into account. The low density region favourable for Wigner crystallization for non-magnetic phase is found to be at rs=15.0. The structure dependent Wannier functions which give proper localized representation for Wigner electrons are employed in the calculation. (author)

352

Structural Tolerances of Optical Characteristics in Various types of Photonic Lattices  

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Full Text Available A systematic study of various photonic crystal lattices and their optical characteristics is carried out in this paper. Sensitivity of both dispersion and effective mode area characteristics to deviations of particular structural parameters of the lattices are the main studied topics. The presented results can be exploited during the design of fibers and new devices utilizing the studied lattices, when strict requirements on optical characteristics of the fabricated devices are imposed. Performance benefits for the implementation of particular lattices types in photonic designs are shown.

Stanislav Kraus

2014-01-01

353

Diffusion X-ray scattering by multilayer structures of the waveguide type  

International Nuclear Information System (INIS)

To define the statistical characteristics of interfaces of the four-layer waveguide-type structure, the diffusion X-ray scattering methods are used. The algorithms for solving the inverse scattering problem based on the complex simulation of experimental reflection spectra, angular scattering spectra and oscillations curves are developed. The values of the root-mean-square height of roughnesses of all interfaces and two-scale longitudinal and transverse correlation length are determined. The resonant amplification of the diffusion scattering is detected in the range of waveguide wave excitation

354

A note on the prolongation structure of the cubically nonlinear integrable Camassa-Holm type equation  

International Nuclear Information System (INIS)

In this Letter, we formulate an exterior differential system for the newly discovered cubically nonlinear integrable Camassa-Holm type equation. From the exterior differential system we establish the integrability of this equation. We then study Cartan prolongation structure of this equation. We also discuss the method of identifying conservation laws and Baecklund transformation for this equation from the identified exterior differential system. -- Highlights: ? An exterior differential system for a cubic nonlinear integrable equation is given. ? The conservation laws from the exterior differential system is derived. ? The Baecklund transformation from the Cartan-Ehresmann connection is obtained.

355

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

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Full Text Available 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 (60?70 %, which were effected by hydrochloric acid with concentrations of 1 M and above.

MAGDALENA TOMASEVIC-CANOVIC

2004-04-01

356

Development of radiation hard edgeless detectors with current terminating structure on p-type silicon  

International Nuclear Information System (INIS)

The development of edgeless Si detectors was stimulated by the tasks of the total pp cross-section study in the TOTEM experiment at the Large Hadron Collider at CERN. For this, the dead region at the detector diced side should be reduced below 50 ?m. This requirement is successfully realized in edgeless Si detectors with current terminating structure (CTS), which are now operating at LHC. The development of the experiment and future LHC upgrade need the elaboration of radiation hard version of edgeless Si detectors. The current investigation represents an extension in understanding on edgeless detectors operation and development of a new issue - edgeless detectors with CTS on p-type Si.

357

Toothpaste lava: Characteristics and origin of a lava structural type transitional between pahoehoe and aa  

Science.gov (United States)

Toothpaste lava, an important basalt structural type which illustrates the transition from pahoehoe to aa, is particularly well displayed on the 1960 Kapoho lava of Kilauea Volcano. Its transitional features stem from a viscosity higher than that of pahoehoe and a rate of flow slower than that of aa. Viscosity can be quantified by the limited settling of olivine phenocrysts and rate of flow by field observations related to the low-angle slope on which the lava flowed. Much can be learned about the viscosity, rheologic condition, and flow velocity of lavas long after solidification by analyses of their structural characteristics, and it is possible to make at least a semiquantitative assessment of the numerical values of these parameters.

Rowland, Scott K.; Walker, George P. L.

1987-08-01

358

Electronic structure of ionic PbFCl-type compounds under pressure  

CERN Document Server

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.

Kanchana, V; Rajagopalan, M

2003-01-01

359

NMR analysis of type III antifreeze protein intramolecular dimer. Structural basis for enhanced activity.  

Science.gov (United States)

The structure of a new antifreeze protein (AFP) variant, RD3, from antarctic eel pout (Rhigophila dearborni) with enhanced activity has been determined for the first time by nuclear magnetic resonance spectroscopy. RD3 comprises a unique translational topology of two homologous type III AFP globular domains, each containing one flat, ice binding plane. The ice binding plane of the N domain is located approximately 3.5 A "behind" that of the C domain. The two ice binding planes are located laterally with an angle of 32 +/- 12 degrees between the planes. These results suggest that the C domain plane of RD3 binds first to the ice [1010] prism plane in the direction, which induces successive ice binding of the N domain in the direction. This manner of ice binding caused by the unique structural topology of RD3 is thought to be crucial for the significant enhancement of antifreeze activity, especially at low AFP concentrations. PMID:11010977

Miura, K; Ohgiya, S; Hoshino, T; Nemoto, N; Suetake, T; Miura, A; Spyracopoulos, L; Kondo, H; Tsuda, S

2001-01-12

360

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

 
 
 
 
361

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

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Full Text Available 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 wasobserved. To get comparative samples for further durability evaluation, the infraredabsorption spectroscopy analysis was performed. Further research will continue withexamination of the joint quality of specimens in long-term external exposition andmacromolecular changes in adhesive structure.

ANNA BENESOVA

2012-01-01

362

Investigation of heat and mass transfer in a gauze-type structured packing liquid desiccant dehumidifier  

Energy Technology Data Exchange (ETDEWEB)

In this experimental investigation, a packed bed column suitable for 5-ton hybrid cooling system has been designed to study the absorption of water vapour from moist air by contact with aqueous solutions of calcium chloride. The packing material used in the study was two elements of the BXPEP structured packing and the height of the each element was 17 cm. This packed bed dehumidifier handles desiccant flow rates from 10 to 32 1/min. This paper presents results from a detailed experimental investigation of the heat and mass transfer between a liquid desiccant (calcium chloride) and air in a gauze-type structured packing dehumidifier. The effects of different independent variables such as air inlet absolute humidity, desiccant inlet temperature, flow rate and its concentration on the performance of the dehumidifier have been investigated. (author)

Gandhidasan, P.; Al-Farayedhi, A.A.; Antar, M.A. [King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia). Dept. of Mechanical Engineering

2002-07-01

363

Labyrinth-type domain structure of heteroepitaxial SrMnO2.5 film  

Science.gov (United States)

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.

Kobayashi, Shunsuke; Ikuhara, Yuichi; Yamamoto, Takahisa

2013-06-01

364

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

Energy Technology Data Exchange (ETDEWEB)

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.)

Benmachiche, I.

2006-07-15

365

On the Structural Types of Reduplicative in The Book of Songs  

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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

Binghua DONG

2011-12-01

366

Ion beam irradiation effects in strontium zirconium phosphate with NZP-structure type  

International Nuclear Information System (INIS)

Ceramics with the sodium zirconium phosphate or NZP type structure have potential as nuclear waste form and inert matrix materials. For both applications the material will be subjected to self-radiation damage from ?-decay of the incorporated actinides. In this study, ion-beam irradiation using Au- and He-ions has been used to simulate the consequences of ?-decay and the effects of irradiation on the structural and macroscopic properties (density and hardness) have been investigated. Irradiation by Au-ions resulted in a significant volume contraction of ?7%, a reduction in hardness of ?30% and a loss in long-range order at fluences above 1014 Au-ions/cm2. In contrast, little effect on the material properties was noted for samples irradiated with He-ions up to a fluence of 1017 ions/cm2. Thermal annealing was investigated for the highest fluence Au-ion irradiated sample and significant decomposition was observed

367

Crystal structures of Helicobacter pylori type II dehydroquinase inhibitor complexes: new directions for inhibitor design.  

Science.gov (United States)

The crystal structures of the type II dehydroquinase (DHQase) from Helicobacter pylori in complex with three competitive inhibitors have been determined. The inhibitors are the substrate analogue 2,3-anhydroquinate (FA1), citrate, and an oxoxanthene sulfonamide derivative (AH9095). Despite the very different chemical nature of the inhibitors, in each case the primary point of interaction with the enzyme is via the residues that bind the C1 functionalities of the substrate, 3-dehydroquinate, i.e., N76, H102, I103, and H104. The DHQase/AH9095 complex crystal structure shows that sulfonamides can form a scaffold for nonsubstrate-like inhibitors and identifies a large conserved hydrophobic patch at the entrance to the active site as a locus that can be exploited in the development of new ligands. PMID:16480265

Robinson, David A; Stewart, Kirsty A; Price, Nicholas C; Chalk, Peter A; Coggins, John R; Lapthorn, Adrian J

2006-02-23

368

Temperature-dependent structural studies of mullite-type Bi2Fe4O9  

Science.gov (United States)

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 aPseudo-Voigt elements were assigned to Fe-O stretching, Fe-O-Fe bending and O-Fe-O bending vibrations. The shift of the observed modes was described with respect to temperature. An effective linewidth parameter ?corr was determined by autocorrelation analysis between 740 cm-1 and 900 cm-1 for each temperature-dependent spectrum. The break of the slope of ?corr at about 773 K was interpreted as the change of some vibrational modes of the FeO4 tetrahedra. The intrinsic effects observed around 773 K are responsible for extrinsic parameter changes found around 900 K.

Murshed, M. Mangir; Nénert, Gwilherm; Burianek, Manfred; Robben, Lars; Mühlberg, Manfred; Schneider, Hartmut; Fischer, Reinhard X.; Gesing, Thorsten M.

2013-01-01

369

Wildfires alter rodent community structure across four vegetation types in southern California, USA  

Science.gov (United States)

We surveyed burned and unburned plots across four habitat reserves in San Diego County, California, USA, in 2005 and 2006, to assess the effects of the 2003 wildfires on the community structure and relative abundance of rodent species. The reserves each contained multiple vegetation types (coastal sage scrub, chaparral, woodland, and grassland) and spanned from 250 m to 1078 m in elevation. Multivariate analyses revealed a more simplified rodent community structure in all burned habitats in comparison to unburned habitats. Reduction in shrub and tree cover was highly predictive of changes in post-fire rodent community structure in the burned coastal sage scrub and chaparral habitats. Reduction in cover was not predictive for the less substantially burned woodlands and grasslands, for which we hypothesized that interspecific competition played a greater role in post-fire community structure. Across vegetation types, generalists and open habitat specialists typically increased in relative abundance, whereas closed habitat specialists decreased. We documented significant increases in relative abundance of the deer mouse (Peromyscus maniculatus Wagner) and Dulzura kangaroo rat (Dipodomys simulans Merriam). In contrast, we found significant decreases in relative abundance for the California mouse (Peromyscus californicus Gambel), San Diego pocket mouse (Chaetodipus fallax Merriam), desert woodrat (Neotoma lepida Thomas), and brush mouse (Peromyscus boylii Baird). Currently, our research program involves assessment of whether habitat conservation plans (HCPs) in southern California provide long-term protection to HCP covered species, as well as preserve ecosystem function. The scenario of increased wildfires needs to be incorporated into this assessment. We discuss our results in relation to management and conservation planning under a future scenario of larger and more frequent wildfires in southern California.

Brehme, Cheryl S.; Clark, Denise R.; Rochester, Carlton J.; Fisher, Robert N.

2011-01-01

370

The skeleton castings as a new type of cast lattice structures  

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Full Text Available Purpose: of this paper is to present selected achievements in field of new type material - skeleton structures. Actual state of knowledge about periodic cellular materials was described. The aim of this work is to show results about mechanically optimised skeleton casting with octahedron topology. Correctness of technological parameters was investigated by microstructural research. Most important parameters of the manufacturing process were identified.Design/methodology/approach: The influence of technological parameters to the microstructure in different points of casting was described. Simulations of the mould filling processes were also carried out. Real experiments were performed to prove the simulation results. The qualitative and quantitative metallographic analysis was also carried out.Findings: It was found that the octahedron shape of internal cell causes best stress distribution and that the skeleton castings are a good alternative for cellular materials such as metal foams, lattice structures or sandwich panels.Research limitations/implications: Casting methods used to manufacture materials such as described skeleton castings confirmed their usefulness. Not well known and used yet rheological properties of liquid metals allow obtaining shape complicated structures near to metallic foams but with periodic structure.Practical implications: Technological parameters of the skeleton castings manufacturing process were developed. Without use of advanced techniques there is a possibility to manufacture relatively low cost skeleton structures in a typical foundry.Originality/value: Three dimensional cast skeleton structures with internal topology of octahedron confirmed their usefulness as elements used for energy dissipation. Obtaining the homogenous microstructure in the whole volume of complicated shape castings can be achieved.

M. Cholewa

2012-10-01

371

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

International Nuclear Information System (INIS)

Full text: In far scrape-off 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 theoovide support evidence for the recent theory prediction that the error filed generated by scrape-off layer current can ultimately trigger the ELM through the coupling with MHD modes inside the separatrix. (author)

372

NMR investigations of Li+ ion dynamics in the NASICON ionic conductors Li1-xLax/3?2x /3Zr2(PO4)3  

International Nuclear Information System (INIS)

NMR studies of 7Li and 31P nuclei are reported in the 150-900 K temperature range for the Li1-xLax/3?2x /3Zr2(PO4)3 NASICON compounds with x = 0.8, 0.7, 0.6 and 0.3. Magic angle spinning (MAS mode) experiments were performed at room temperature on the 7Li and 31P nuclei. The linewidth and the spin lattice relaxation times of these nuclei are studied versus temperature in the static mode. The spectra recorded in the MAS mode show that the 7Li ions occupy three chemical sites, the occupation of which being very sensitive to the x values but not sensitive to the coexistence of the two varieties C1-bar and R3-barc observed at room temperature in compounds with x?0.5. On the other hand, the 31P nucleus MAS spectra are very sensitive to lithium content but also to the variety coexistence. T1 measurements were performed in a static mode on the 7Li and 31P nuclei. In all the compounds, the 7Li spin lattice relaxation time exhibits two branches with several minima, indicating the complex dynamics for this ion. One of these minima appears in the same temperature range as the minimum of the 31P nucleus T1, strongly suggesting a cross-relaxation process between these nuclei. T1? measurements on 7Li (static mode) allow us to show a slow motion diffe allow us to show a slow motion different from the one probed by the T1. The analysis of the T1? behaviour with temperature and composition allows us to ascribe the motion probed by this time to the oxygen ion motion which monitors the opening and closing of the lithium pathways. A qualitative interpretation of the 7Li T1 results is done; it takes into account the cross-relaxation phenomena between 31P and 7Li and quadrupolar fluctuations.

373

Recent advances in the structural and molecular biology of type IV secretion systems.  

Science.gov (United States)

Bacteria use type IV secretion (T4S) systems to deliver DNA and protein substrates to a diverse range of prokaryotic and eukaryotic target cells. T4S systems have great impact on human health, as they are a major source of antibiotic resistance spread among bacteria and are central to infection processes of many pathogens. Therefore, deciphering the structure and underlying translocation mechanism of T4S systems is crucial to facilitate development of new drugs. The last five years have witnessed considerable progress in unraveling the structure of T4S system subassemblies, notably that of the T4S system core complex, a large 1 MegaDalton (MDa) structure embedded in the double membrane of Gram-negative bacteria and made of 3 of the 12 T4S system components. However, the recent determination of the structure of -3MDa assembly of 8 of these components has revolutionized our views of T4S system architecture and opened up new avenues of research, which are discussed in this review. PMID:24709394

Trokter, Martina; Felisberto-Rodrigues, Catarina; Christie, Peter J; Waksman, Gabriel

2014-08-01

374

The structural and optical properties of Volmer-Weber-type ZnO nanorods  

Energy Technology Data Exchange (ETDEWEB)

Volmer-Weber-type ZnO nanorods (VW ZnO NRs) were fabricated by using a hybrid method combined with RF sputtering and hydrothermal methods. The structural and optical properties of VW ZnO NRs were investigated by using synchrotron X-ray diffraction (XRD), micro-Raman spectroscopy, photoluminescence (PL) spectroscopy and X-ray photoelectron spectroscopy (XPS). It was found that VW ZnO NRs showed wurtzite structure and were vertically standing on a substrate with a compressive stress from the substrate that can be reduced by annealing. In the micro-Raman study, a forbidden E{sub 1}(LO) mode in a bulk ZnO was observed in VW ZnO NRs due to the many edges in NR structures. It was also confirmed that VW ZnO NRs have a wurtzite structure by observing E{sub 2} {sub low} and E{sub 2} {sub high} peaks. In the PL spectra, VW ZnO NRs showed a broad emission in the visible range, especially yellow emission, with a weak UV emission. The UV emission was monotonously enhanced on increasing the annealing temperature. The yellow emission was enhanced in the annealed sample at 200 C due to an evaporation of hydroxyl groups (OH {sup -}) on the surface of VW ZnO NRs. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Park, Se-Jeong; He, Weizhen [Department of Nano Fusion Technology and BK 21 Nano Fusion Technology Division, Pusan National University, Miryang 627-706 (Korea, Republic of); Qiu, Jijun [Research Center for Dielectric and Advanced Matter Physics (RCDAMP), Pusan National University, Busan 609-735 (Korea, Republic of); State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Kim, Jin Woo [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), Gwangju 500-712 (Korea, Republic of); Lee, Ik Jae [Pohang Acceleration Laboratory, Pohang University of Science and Technology (POSTECH), Pohang 790-784 (Korea, Republic of); Kim, Beomkeun [School of Mechanical and Automotive Engineering, Inje University, Gimhae 621-749 (Korea, Republic of); Kim, Hyung-Kook; Hwang, Yoon-Hwae [Department of Nano Fusion Technology and BK 21 Nano Fusion Technology Division, Pusan National University, Miryang 627-706 (Korea, Republic of); Research Center for Dielectric and Advanced Matter Physics (RCDAMP), Pusan National University, Busan 609-735 (Korea, Republic of); Department of Nanomaterials Engineering, Pusan National University, Miryang 627-706 (Korea, Republic of)

2011-05-15

375

Development of Processable PMR-Type Polymides with Star-Branched Structures  

Science.gov (United States)

In the last two decades, high temperature polyimide matrix composites have found broad applications in aerospace structural components, due to their high specific modulus and high specific strength. As matrix resins, aromatic polyimides exhibit exceptional thermal stability and mechanical properties. However, their rodlike structures often result in poor solubility in most common organic solvents, as well as high melt temperature and melt viscosity, making them difficult to process. To overcome this difficulty, flexible linkages including O, SO2 or CH2 non coplanar biphenyl moieties, bulky lateral substituents, and crankshaft structures are often incorporated into the polymer backbones. Addition-curing of low molecular weight polyimides (resins) is another approach to improve processability. One of the most successfully developed materials has been PMR-15 (Polymerization of Monomer Reactants, molecular weight of 1500 g/mol), because of its good combination of thermal and mechanical properties and ease of processability. However, due to the high melt viscosity of PMR-type resins, use of more economical processing methods, such as resin transfer molding (RTM), is not possible. Recent research has focused on the incorporation of trifunctional monomers into addition-curing polyimides in an attempt to improve the processability of these polymers. The objective of this research is to use an aromatic triamine, 1,3,5 tris (4-aminophenoxy) benzene, to prepare new resin systems with starbranched structures. The glass transition temperatures (Tg's) and thermal oxidative stability TOS) of these polymers are compared to their linear counterparts and PMR-15.

Nguyen, Baochau N.; Eby, R. K.; Meador, Michael A.

1999-01-01

376

Structural and electronic properties of type-I and type-VIII Ba8Ga16Sn30 clathrates under compression  

International Nuclear Information System (INIS)

The total energy and electronic structures for type-I (? phase) and type-VIII (? phase) Ba8Ga16Sn30 clathrates under hydrostatic pressure have been investigated using density functional theory (DFT) calculations. It was found that the type-VIII phase is more stable than the type-I one at ambient conditions and that ??? phase transition can not occur under hydrostatic pressure. The band structures show that the type-I and type-VIII Ba8Ga16Sn30 are indirect semiconductors with band gaps of 0.24 eV and 0.19 eV, respectively. The results suggested that type-I clathrate Ba8Ga16Sn30 has a larger value of the thermoelectric (TE) power than that of type-VIII clathrate. We found that pressure tuning changes the k-point of conduction band minimum (CBM) in the Brillouin zone for ?-phase, but it is not the case for ?-phase. Furthermore, the results show that the pressure can change the interaction between guest atoms and the host lattice, and consequently results in the decrease of the band gap of ?-phase and the increase of the band gap of ?-phase, indicating that the pressure effect can play an important role in the magnitude of the TE power.

377

Structural and electronic properties of type-I and type-VIII Ba8Ga16Sn30 clathrates under compression  

Science.gov (United States)

The total energy and electronic structures for type-I (? phase) and type-VIII (? phase) Ba8Ga16Sn30 clathrates under hydrostatic pressure have been investigated using density functional theory (DFT) calculations. It was found that the type-VIII phase is more stable than the type-I one at ambient conditions and that ??? phase transition can not occur under hydrostatic pressure. The band structures show that the type-I and type-VIII Ba8Ga16Sn30 are indirect semiconductors with band gaps of 0.24 eV and 0.19 eV, respectively. The results suggested that type-I clathrate Ba8Ga16Sn30 has a larger value of the thermoelectric (TE) power than that of type-VIII clathrate. We found that pressure tuning changes the k-point of conduction band minimum (CBM) in the Brillouin zone for ?-phase, but it is not the case for ?-phase. Furthermore, the results show that the pressure can change the interaction between guest atoms and the host lattice, and consequently results in the decrease of the band gap of ?-phase and the increase of the band gap of ?-phase, indicating that the pressure effect can play an important role in the magnitude of the TE power.

Li, D. C.; Fang, L.; Deng, S. K.; Kang, K. Y.; Shen, L. X.; Wei, W. H.; Ruan, H. B.

2012-04-01

378

Structural, infrared, magnetic and microwave absorption properties of rare earth doped X-type hexagonal nanoferrites  

International Nuclear Information System (INIS)

Highlights: •A series of X-type hexagonal ferrites were prepared by sol–gel method. •The XRD analysis showed that the X-type hexagonal structure. •The c/a ratio of these samples falls in the range of X-type hexagonal ferrites. •The magnetic properties enhances with the increase of Nd–Co contents. •The samples show the reflection loss at smaller frequencies. -- Abstract: A series of Sr2?xNdxNi2 Fe28?yCoyO46 (x = 0.02, 0.04, 0.06, 0.08, 0.10 and y = 0.1, 0.2, 0.3, 0.4, 0.5) X-type hexagonal ferrites has been prepared by sol–gel method at 1250 °C for 6 h. XRD analysis shows the single phase of the prepared ferrites material. The lattice constant values and c/a ratio shows that the present assembled material belongs to the family X-type hexagonal ferrites. The peaks in the FTIR spectra are the characteristics of the hexagonal ferrites. The crystallite size measured by Scherer formula is in good agreement with the crystallite size measured by TEM and HRTEM. The enhancement in the magnetic properties can easily be observed with the doping of rare earth element Nd3+ and divalent Co2+. Due to high saturation and low coercivity values the present material can be good microwave absorber. The temperature dependent saturation and remanance magnetization decreases monotonically with temperature. The minimum value of reflection loss enhances with the substituent and the attenuation constant results are in agreement with reflection loss results

379

Structural, infrared, magnetic and microwave absorption properties of rare earth doped X-type hexagonal nanoferrites  

Energy Technology Data Exchange (ETDEWEB)

Highlights: •A series of X-type hexagonal ferrites were prepared by sol–gel method. •The XRD analysis showed that the X-type hexagonal structure. •The c/a ratio of these samples falls in the range of X-type hexagonal ferrites. •The magnetic properties enhances with the increase of Nd–Co contents. •The samples show the reflection loss at smaller frequencies. -- Abstract: A series of Sr{sub 2?x}Nd{sub x}Ni{sub 2} Fe{sub 28?y}Co{sub y}O{sub 46} (x = 0.02, 0.04, 0.06, 0.08, 0.10 and y = 0.1, 0.2, 0.3, 0.4, 0.5) X-type hexagonal ferrites has been prepared by sol–gel method at 1250 °C for 6 h. XRD analysis shows the single phase of the prepared ferrites material. The lattice constant values and c/a ratio shows that the present assembled material belongs to the family X-type hexagonal ferrites. The peaks in the FTIR spectra are the characteristics of the hexagonal ferrites. The crystallite size measured by Scherer formula is in good agreement with the crystallite size measured by TEM and HRTEM. The enhancement in the magnetic properties can easily be observed with the doping of rare earth element Nd{sup 3+} and divalent Co{sup 2+}. Due to high saturation and low coercivity values the present material can be good microwave absorber. The temperature dependent saturation and remanance magnetization decreases monotonically with temperature. The minimum value of reflection loss enhances with the substituent and the attenuation constant results are in agreement with reflection loss results.

Sadiq, Imran, E-mail: khanphysics@yahoo.com [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Khan, Imran [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan); Rebrov, Evgeny V. [School of Chemistry and Chemical Engineering, Queen’s University Belfast (United Kingdom); Ashiq, Muhammad Naeem [Institute of Chemical Sciences, Bahauddin Zakariya University, Multan 60800 (Pakistan); Naseem, Shahzad [Centre for Solid State Physics, University of Punjab, Lahore (Pakistan); Rana, M.U., E-mail: mazharrana@bzu.edu.pk [Department of Physics, Bahauddin Zakariya University, Multan 60800 (Pakistan)

2013-09-05

380

Oxide-ion conduction and dielectric relaxations for fluorite type structure  

Energy Technology Data Exchange (ETDEWEB)

The oxide-ion conduction and dielectric properties of 10 mol% CaO stabilized ZrO{sub 2} (10CSZ) and 25 mol% Y{sub 2}O{sub 3} stabilized Bi{sub 2}O{sub 3} (25YSB) which are oxide ion conductors having a fluorite-type structure were investigated. The numerical analyses for the frequency dependences of dielectric constants ({epsilon}{sub r}') and dielectric loss factors ({epsilon}{sub 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 Y{sup 3+}-doped Bi{sup 3+} site. On the other hand, two Debye-type dipoles observed in 10CSZ were assigned to two kinds of associates, [Ca{sub Zr}''-V{sub o}{sup {center_dot}{center_dot}}]{center_dot}, which was due to dopant-vacancy associates with two different distances between (Ca{sub Zr}'') and (V{sub o}{sup {center_dot}{center_dot}}). The frequency dependence of dielectric loss tangent (tan{delta}) in 25YSB was ascribed to the interface loss due to the charged current, while that of tan{delta} in 8YSZ was ascribed to the Debye-type dipoles in addition to the interface loss.

Yagi, Yuhji; Kawamoto, Jun-ichi; Saito, Miwa; Yamamura, Hiroshi, E-mail: r200870209bq@kanagawa-u.ac.jp [Kanagawa University, 3-27-1 Rokkakubashi, Kanagawa-ku, Yokohama 221-8686 (Japan)

2011-06-15

 
 
 
 
381

Structures of type B ribose 5-phosphate isomerase from Trypanosoma cruzi shed light on the determinants of sugar specificity in the structural family  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Ribose-5-phosphate isomerase (Rpi; EC 5.3.1.6) is a key activity of the pentose phosphate pathway. Two unrelated types of sequence/structure possess this activity: type A Rpi (present in most organisms) and type B Rpi (RpiB) (in some bacteria and parasitic protozoa). In the present study, we report enzyme kinetics and crystallographic studies of the RpiB from the human pathogen, Trypanosoma cruzi. Structures of the wild-type and a Cys69Ala mutant enzyme, alone or bound to phosphate, D-ribose ...

Stern, Ana Laura; Naworyta, Agata; Cazzulo, Juan J.; Mowbray, Sherry L.

2011-01-01

382

Some design constraints required for the assembly of software components: The incorporation of atomic abstract types into generically structured abstract types  

Science.gov (United States)

It is nearly axiomatic, that to take the greatest advantage of the useful features available in a development system, and to avoid the negative interactions of those features, requires the exercise of a design methodology which constrains their use. A major design support feature of the Ada language is abstraction: for data, functions processes, resources, and system elements in general. Atomic abstract types can be created in packages defining those private types and all of the overloaded operators, functions, and hidden data required for their use in an application. Generically structured abstract types can be created in generic packages defining those structured private types, as buildups from the user-defined data types which are input as parameters. A study is made of the design constraints required for software incorporating either atomic or generically structured abstract types, if the integration of software components based on them is to be subsequently performed. The impact of these techniques on the reusability of software and the creation of project-specific software support environments is also discussed.

Johnson, Charles S.

1986-01-01

383

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

CERN Document Server

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...

Gai, Moshe

2014-01-01

384

Synthesis and ferroelectric properties of rare earth compounds with tungsten bronze-type structure  

International Nuclear Information System (INIS)

Highlights: · Polycrystalline materials with the tungsten bronze-type structure have been synthesized and characterized. · Effect of the incorporation of rare earth ions and paramagnetic cations (Fe3+) into a matrix ferroelectrically active was studied. · Ferroelectric transition is pronounced by a large thermal hysteresis during the heating and cooling cycles. · Phase transitions around Tc were confirmed by differential scanning calorimetry (DSC) measurements. - Abstract: Polycrystalline materials with a general formula Pb2Na0.8R0.2Nb4.8Fe0.2O15 (R = Dy, Eu, Sm, Nd, La) have been synthesized, in air by a high temperature solid state reaction method. X-ray diffraction study, at room temperature, revealed that they crystallize in the tungsten bronze-type structure. Dielectric properties were performed, in the temperature range 25-500 deg. C, at three different frequencies 10, 100 and 1000 kHz. The ferroelectric transition is pronounced by a large thermal hysteresis during the heating and cooling cycles. The determined Curie temperature values Tc were discussed as a function of rare earth size. Phase transitions around Tc for the investigated compounds were confirmed by differential scanning calorimetry (DSC) measurements.

385

Generalized N=1 and N=2 structures in M-theory and type II orientifolds  

CERN Document Server

We consider M-theory and type IIA reductions to four dimensions with N=2 and N=1 supersymmetry and discuss their interconnection. Our work is based on the framework of Exceptional Generalized Geometry (EGG), which extends the tangent bundle to include all symmetries in M-theory and type II string theory, covariantizing the local U-duality group E7. We describe general N=1 and N=2 reductions in terms of SU(7) and SU(6) structures on this bundle and thereby derive the effective four-dimensional N=1 and N=2 couplings, in particular we compute the Kahler and hyper-Kahler potentials as well as the triplet of Killing prepotentials (or the superpotential in the N=1 case). These structures and couplings can be described in terms of forms on an eight-dimensional tangent space where SL(8) contained in E7 acts, which might indicate a description in terms of an eight-dimensional internal space, similar to F-theory. We finally discuss an orbifold action in M-theory and its reduction to O6 orientifolds, and show how the pr...

Graña, Mariana

2012-01-01

386

Structural features of the gene encoding human muscle type carnitine palmitoyltransferase I.  

Science.gov (United States)

We isolated a human muscle type of carnitine palmitoyltransferase I (CPTI-M) genomic clone and determined its entire nucleotide sequence. By comparison of the nucleotide sequence of the genomic clone with that of cDNA, we determined the intron/exon junctions. For detection of the exon(s) in the 5'-region of the CPTI-M gene, we isolated cDNA clones corresponding to the 5'-region of its transcript by 5'-rapid amplification of cDNA ends (5'-RACE method). Results showed two alternative exons, 1A and 1B, that do not encode amino acids in the 5'-region of the human CPTI-M gene. The gene encoding human CPTI-M was found to consist of two 5'-non-coding exons, 18 coding exons and one 3'-non-coding exon spanning approximately 10 kbp. Furthermore, on analysis of the 5'-flanking region, a putative gene encoding a 'choline kinase homologue' was found to be located only about 300 bp upstream from exon 1A of the human CPTI-M gene. Comparison of the gene structure of human CPTI-M with the reported partial gene structure of human liver type CPTI (CPTI-L) showed that the intron insertion sites were completely conserved in these two genes. PMID:9224698

Yamazaki, N; Yamanaka, Y; Hashimoto, Y; Shinohara, Y; Shima, A; Terada, H

1997-06-16

387

Growth of rectangular hollow tube crystals with rutile-type structure in supercritical fluids  

Science.gov (United States)

Super critical fluids are well known as suitable solvents for dissolution and extraction processes, because it exhibits extreme high solubility and reactivity. However further experimental development using supercritical fluid would offer new insight in material science, especially the synthesis and crystal growth of novel materials. We report the successful growth of single crystals with the rutile-type structure (TiO2, Co-doped TiO2, SiO2, GeO2 and SnO2) in supercritical fluids (water or oxygen) using a laser heated diamond-anvil cell up to a pressure of 7 GPa. The resultant product showed the rectangular hollow tube morphology, a several tens of microns in length and a wall thickness of less than 500 nm. TEM analyses demonstrated that this rectangular hollow tube single crystals were surrounded by the {110} faces and grown along the [001] direction. The preferential growth of {110} faces is consistent with the lowest surface energy of {110} faces of the rutile-type structure. In addition, the rapid cooling rate in LHDAC and high solubility of supercritical fluids also play an important role for the formation of the rectangular hollow tube. The details of the synthesis procedure, characterization and growth mechanism are discussed in this paper.

Niwa, K.; Ikegaya, H.; Taguchi, T.; Muto, S.; Tokunaga, T.; Hasegawa, M.

2014-05-01

388

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

Directory of Open Access Journals (Sweden)

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.

Castejón, L.

1997-12-01

389

High-pressure synthesis of ferromagnetic Mn sub 3 Ge with the Cu sub 3 Au-type structure  

CERN Document Server

A new intermetallic compound, Mn sub 3 Ge, has been synthesized by direct reaction of elemental components at 6.2 GPa and 1000 deg. 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 L1 sub 2 -type (Cu sub 3 Au-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.

Takizawa, H; Uheda, K; Endo, T

2002-01-01

390

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2012-03-27

391

Structure and stability of Ba-Cu-Ge type-I clathrates  

CERN Document Server

We have prepared samples of nominal type Ba$_{8}$Cu$_{x}$Ge$_{46-x}$ by induction melting and solid state reaction. Analysis has shown that these materials form type-I clathrates, with copper content between $x$ = 4.6 and 5.2, nearly independent of the starting composition. X-ray powder diffraction and single-crystal electron diffraction results confirmed the cubic type-I clathrate structure to be the main phase in these materials. For starting compositions of Ba$_{8}$Cu$_{2}$Ge$_{44}$ and Ba$_{8}$Cu$_{4}$Ge$_{42}$, electron microprobe analysis demonstrated the formation of clathrate with average composition Ba$_{7.8}$Cu$_{4.7}$Ge$_{39.3}$, along with elemental Ge and a small amount of BaGeO$_{2}$. In a Ba$_{8}$Cu$_{6}$Ge$_{40}$ preparation, Cu content of the clathrate phase increased to x = 5.1, while excess Cu appeared as a Ge$_{3}$Cu$_{5}$ phase. The stability of the $x \\approx$ 5 composition in Ba$_{8}$Cu$_{x}$Ge$_{46-x}$ we attribute to an electron magic-number mechanism, associated with a gap or deep mi...

Li, Y; Gou, W; Khandekar, S; Li, Yang; Chi, Ji; Gou, Weiping; Khandekar, Sameer; Jr, Joseph H. Ross

2003-01-01

392

Recent Structural Evolution of Early-Type Galaxies: Size Growth from z=1 to z=0  

CERN Document Server

Strong size and internal density evolution of early-type galaxies between z~2 and the present has been reported by several authors. Here we analyze samples of nearby and distant (z~1) galaxies with dynamically measured masses in order to confirm the previous, model-dependent results and constrain the uncertainties that may play a role. Velocity dispersion measurements are taken from the literature for 50 morphologically selected 0.8type galaxies with typical masses 2e11 Msol. Sizes are determined with ACS imaging. We compare the distant sample with a large sample of nearby (0.04type galaxies extracted from the SDSSfor which we determine sizes, masses, and densities in a consistent manner, using simulations to quantify systematic differences between the size measurements of nearby and distant galaxies. We find a highly significant structural difference between the nearby and distant samples, regardless of sample selection effects. The implied evolution ...

van der Wel, Arjen; Zirm, Andrew W; Franx, Marijn; Rettura, Alessandro; Illingworth, Garth D; Ford, Holland C

2008-01-01

393

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

DEFF Research Database (Denmark)

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 approach. The best overall network used as input amino acid composition, averaged surface accessibility predictionstogether with substitution matrix profile encoding of the sequence. To improve prediction on isolated (single) sites, networks were trained on isolated sites only. The final method combines predictions from the best overall network and the best isolated site network; this prediction method correctly predicted 76% of the glycosylated residues and 93% of the nonglycosylated residues. NetOGlyc 3.1 can predict sites for completely new proteins without losing its performance. The fact that the sites 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.

Julenius, Karin; MØlgaard, Anne

2004-01-01

394

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

DEFF Research Database (Denmark)

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 approach. The best overall network used as input amino acid composition, averaged surface accessibility predictionstogether with substitution matrix profile encoding of the sequence. To improve prediction on isolated (single) sites, networks were trained on isolated sites only. The final method combines predictions from the best overall network and the best isolated site network; this prediction method correctly predicted 76% of the glycosylated residues and 93% of the nonglycosylated residues. NetOGlyc 3.1 can predict sites for completely new proteins without losing its performance. The fact that the sites 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.

Julenius, Karin; MØlgaard, Anne

2005-01-01

395

Reassessing the type I dehydroquinate dehydratase catalytic triad: kinetic and structural studies of Glu86 mutants.  

Science.gov (United States)

Dehydroquinate dehydratase (DHQD) catalyzes the third reaction in the biosynthetic shikimate pathway. Type I DHQDs are members of the greater aldolase superfamily, a group of enzymes that contain an active site lysine that forms a Schiff base intermediate. Three residues (Glu86, His143, and Lys170 in the Salmonella enterica DHQD) have previously been proposed to form a triad vital for catalysis. While the roles of Lys170 and His143 are well defined-Lys170 forms the Schiff base with the substrate and His143 shuttles protons in multiple steps in the reaction-the role of Glu86 remains poorly characterized. To probe Glu86's role, Glu86 mutants were generated and subjected to biochemical and structural study. The studies presented here demonstrate that mutant enzymes retain catalytic proficiency, calling into question the previously attributed role of Glu86 in catalysis and suggesting that His143 and Lys170 function as a catalytic dyad. Structures of the Glu86Ala (E86A) mutant in complex with covalently bound reaction intermediate reveal a conformational change of the His143 side chain. This indicates a predominant steric role for Glu86, to maintain the His143 side chain in position consistent with catalysis. The structures also explain why the E86A mutant is optimally active at more acidic conditions than the wild-type enzyme. In addition, a complex with the reaction product reveals a novel, likely nonproductive, binding mode that suggests a mechanism of competitive product inhibition and a potential strategy for the design of therapeutics. PMID:23341204

Light, Samuel H; Anderson, Wayne F; Lavie, Arnon

2013-04-01

396

Structural and population characterization of MrkD, the adhesive subunit of type 3 fimbriae.  

Science.gov (United States)

Type 3 fimbriae are adhesive organelles found in enterobacterial pathogens. The fimbriae promote biofilm formation on biotic and abiotic surfaces; however, the exact identity of the receptor for the type 3 fimbriae adhesin, MrkD, remains elusive. We analyzed naturally occurring structural and functional variabilities of the MrkD adhesin from Klebsiella pneumoniae and Escherichia coli isolates of diverse origins. We identified a total of 33 allelic variants of mrkD among 90 K. pneumoniae isolates and 10 allelic variants among 608 E. coli isolates, encoding 11 and 9 protein variants, respectively. Based on the level of accumulated silent variability between the alleles, mrkD was acquired a relatively long time ago in K. pneumoniae but recently in E. coli. However, unlike K. pneumoniae, mrkD in E. coli is actively evolving under a strong positive selection by accumulation of mutations, often targeting the same positions in the protein. Several naturally occurring MrkD protein variants from E. coli were found to be significantly less adherent when tested in a mannan-binding assay and showed reduced biofilm-forming capacity. Functional examination of the MrkD adhesin in flow chamber experiments determined that it interacts with Saccharomyces cerevisiae cells in a shear-dependent manner, i.e., the binding is catch-bond-like and enhanced under increasing shear conditions. Homology modeling strongly suggested that MrkD has a two-domain structure, comprising a pilin domain anchoring the adhesin to the fimbrial shaft and a lectin domain containing the binding pocket; this is similar to structures found in other catch-bond-forming fimbrial adhesins in enterobacteria. PMID:24123820

Stahlhut, Steen G; Chattopadhyay, Sujay; Kisiela, Dagmara I; Hvidtfeldt, Kristian; Clegg, Steven; Struve, Carsten; Sokurenko, Evgeni V; Krogfelt, Karen A

2013-12-01

397

Structure/function of the inhibition of human 3?-hydroxysteroid dehydrogenase type 1 and type 2 by trilostane  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The human type 1 (placenta, breast tumors) and type 2 (gonads, adrenals) isoforms of 3?-hydroxysteroid dehydrogenase/isomerase (3?-HSD) are key enzymes in biosynthesis of all active steroid hormones. Human 3?-HSD1 is a critical enzyme in the conversion of DHEA to estradiol in breast tumors and may be a major target enzyme for the treatment of breast cancer. 3?-HSD2 participates in the production of cortisol and aldosterone in the human adrenal gland. The goals of this project are to evalu...

Thomas, James L.; Mack, Vance L.; Glow, Jason A.; Moshkelani, Delaram; Terrell, J. Ross; Bucholtz, Kevin M.

2008-01-01

398

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

Science.gov (United States)

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

Gagnon, Lise; Peretz, Isabelle; Fülöp, Tamàs

2009-01-01

399

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

CERN Document Server

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...

Zhang, J

2009-01-01

400

Enantiomer Discrimintation Illustrated by the High Resolution Crystal Structures of Type 4 Phosphodiesterase  

Energy Technology Data Exchange (ETDEWEB)

Type 4 phosphodiesterase (PDE4) inhibitors are emerging as new treatments for a number of disorders including asthma and chronic obstructive pulmonary disease. Here we report the biochemical characterization on the second generation inhibitor (+)-1 (L-869298, IC50 = 0.4 nM) and its enantiomer (-)-1 (L-869299, IC50 = 43 nM) and their cocrystal structures with PDE4D at 2.0 Angstroms resolution. Despite the 107-fold affinity difference, both enantiomers interact with the same sets of residues in the rigid active site. The weaker (-)-1 adopts an unfavorable conformation to preserve the pivotal interactions between the Mg-bound waters and the N-oxide of pyridine. These structures support a model in which inhibitors are anchored by the invariant glutamine at one end and the metal-pocket residues at another end. This model provides explanations for most of the observed structure-activity relationship and the metal ion dependency of the catechol-ether based inhibitors and should facilitate their further design.

Huai,Q.; Sun, Y.; Wang, H.; MacDonald, D.; Aspiotis, R.; Robinson, H.; Huang, Z.; Ke, H.

2006-01-01

 
 
 
 
401

Relationships of structure to properties of various type RBa2Cu3Ox compounds  

International Nuclear Information System (INIS)

Verification of the structure of certain RBa2Cu3Ox type compounds is carried out using the neutron diffraction analysis of a powder at 298 K. The superconducting NdBa2Cu3O6.85, YBa2Cu3O6.91 and ErBa2Cu3O6.99 phases are shown to have the rhombic symmetry. In some rare-earth elements Cu-O short distance (? 0.185 nm) decreases with the growth of the rare-earth metal cation size, but the average Cu-O distance in extended chains remains practically constant. Verification of the structure of the YBa2Cu3O7-x phase has shown that transition to tetragonal modification of the YBa2Cu3O6 composition occurs without structure destruction. The latter phase possesses semiconducting properties and it is not a superconductor. On the basis is supposed that superconductivity in perovskites deficient by oxygen is caused by the presence of (-Cu-O-)n-chains. 5 refs.; 1 fig.; 4 tabs

402

Oxidative dehydrogenation of isobutyl alcohol over different structure type of zeolites  

International Nuclear Information System (INIS)

Full text: Partial heterogen-catalytic of aliphatic alcohols is perspective method for production of important oxygen-containing compounds. Numerous of the literature data testify that the different mixed oxides of metals show the relatively high catalytic activity in the reactions of oxidation of aliphatic alcohols. Until recently however little attention had been given to the possibility of using of the modified zeolites for promoting these reactions. The present paper is devoted to oxidative dehydrogenation of isobutyl alcohol in the presence of molecular oxygen over different structure type of synthetical (A, X, Y, ZSM-5) and natural zeolites modified by cations of transition elements (Cu2+, Sn2+, Ni2+, Co2+, Fe2+ and Pd2+) for the purpose of selection of an active catalyst for production of corresponding aldehyde. For making of active catalyst on the first stage the study was carried out ever mono- and on the second stage over bimethalzeolite catalysts. It has been established that for each of zeolite has there optimum concentration of transition element cation in the dependence of structure of zeolites. It has been found that, the mono metallic catalysts on the basis of synthetical zeolites more active in this reaction than catalysts on the basis of natural zeolites. Introduction of second metal cation (Pd2+) into structure of mono metallic catalyst leaded considerable increasing of conlyst leaded considerable increasing of conversion of alcohol and selectivity of the process and stability of operation of catalysts

403

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

Science.gov (United States)

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

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

404

Crystal structure of a copper-transporting PIB-type ATPase  

DEFF Research Database (Denmark)

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 en