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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

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

3

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

4

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.

5

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

6

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

7

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

8

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

9

Modeling Ionic Conductivity in Nasicon Structures  

Science.gov (United States)

Considering only the structure of oxygen lattice and employing bond valence equations, the conduction geometry and the activation energy of Na+ motion in Nasicons are modeled. This is performed by calculating the valence sum m(x, y, z) for a grid of points inside the oxygen lattice, then by following with iterative procedures the pathway with lowest relative m(x, y, z) values, starting from a specified position and initial direction. After a certain trajectory the Na+ ion will reach a second position in the lattice, which will usually correspond to a known crystallographic position. Different rhombohedral and monoclinic Nasicons are examined, enabling us to verify some the ionic movement. Structural parameters governing conduction are described, based on the distortions of real structures from an idealized (archetype) Nasicon structure, in turn modeled by bond valence equations.

Mazza, Daniele

2001-01-01

10

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)

11

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

12

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

International Nuclear Information System (INIS)

A new complete solid solution of NASICON-type compounds between LiZr2(PO4)3 and La1/3Zr2(PO4)3 was evidenced with the general formula Li1- x La x /3Zr2(PO4)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+?1/3La3++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 Li1- x La x /3?2 x /3Zr2(PO4)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-barc), while at lower temperature, their structure distorts to a triclinic form (s.g. C 1-bar), as observed for LiZr2(PO4)3 prepared above 1100 deg. C. Moreover, in this domain, the reversible transition is clersible 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)

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  

Science.gov (United States)

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

Structural and Luminescent Properties of a Nasicon-Type Phosphate Cu I0.5Mn II0.25Zr 2(PO 4) 3  

Science.gov (United States)

The phosphate CuI0.5MnII0.25Zr2(PO4)3 can be obtained at 1000°C by exchange reaction in CuII0.5Zr2(PO4)3. It crystallizes in the rhombohedral system (space group Roverline3) with the parameters ah=8.8352(1) Å and ch=22.254(5) Å in the equivalent hexagonal cell. The structure refined by the Rietveld method is typical of Nasicon-type structure. Mn2+ ions occupy partially the M1 site, while Cu+ ions are distributed over the M1 and M2 sites generated by the space group. This compound exhibits two fluorescences, occurring in the violet and orange regions and assigned respectively to isolated Cu+ and Mn2+ ions. Two other luminescences detected in the blue and green range at low temperature correspond respectively to (Cu2)+ and (Cu+)2 pairs. Efficient energy transfer Cu+?Mn2+ is observed at room temperature strengthening the orange emission of Mn2+ in the M1 site.

Mouline, A.; Alami, M.; Brochu, R.; Olazcuaga, R.; Parent, C.; Le Flem, G.

2000-07-01

19

Elaboration and characterization of new nasicon type copper phosphates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Les phosphates de cuivre de type NASICON CuxM2(PO4)3 (x=0,5 pour Cu2+; x=1 pour Cu+) (M=Ti, Zr) sont des matériaux remarquables par leurs propriétés catalytiques et luminescentes. L'établissement de modèles rendant compte de ces propriétés à nécessité la localisation du cuivre et la connaissance précise de son environnement par diverses techniques complémentaires : EXAFS, diffraction de neutrons, RMN, microscopie électronique. Le caractère lacunaire de ces phosphates a permis l'...

Bussereau, Isabelle

1990-01-01

20

BRIEF COMMUNICATION. Analyse Structurale par Spectroscopie Raman et Infrarouge de Quelques Phosphates de Cuivre de Type Nasicon  

Science.gov (United States)

Les spectres Raman et Infrarouge des phosphates de cuivre de type Nasicon Cu IM 2(PO 4) 3, Cu II0,5M 2(PO 4) 3et H 0,5Cu I0,5M 2(PO 4) 3( M= Ti,Zr) ont été étudiés. Une analyse de groupe facteur a permis de préciser les modes internes de l'anion PO 3-4. Des diagrammes de corrélation pour différentes symétries du site de PO 4dans le type structural Nasicon ont été proposés. L'évolution des spectres est corrélée avec celle de la structure Nasicon. The Raman and infrared absorption spectra of Nasicon-type copper phosphates with formulas Cu IM 2(PO 4) 3, Cu II0.5M 2(PO 4) 3, and H 0.5Cu I0.5M 2(PO 4) 3( M= Ti,Zr) have been investigated. A factor group analysis leads to determination of internal modes of the PO 3-4anion. Correlation diagrams for various site symmetries of PO 4in the Nasicon-type structure have been proposed. The evolution of the spectra is discussed in relation with the structure.

Le Polles, Ghislaine; Videau, Jean-Jacques; Olazcuaga, Roger; Couzi, Michel

1996-12-01

 
 
 
 
21

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.

22

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

23

Tetravalent Zr{sup 4+} or Hf{sup 4+} ion conduction in NASICON type solids  

Energy Technology Data Exchange (ETDEWEB)

New tetravalent cation conductors of zirconium or hafnium niobium phosphate, MNb(PO{sub 4}){sub 3} (M=Zr, Hf) with NASICON (Na{sup +} Ion Super Ionic CONductors) type structure, which show the high ion conductivity among the tetravalent ion conducting solids, were synthesized. The MNb(PO{sub 4}){sub 3} was designed by strictly selecting the structure and the comprising elements and the conductivity reaches the region of the representative divalent oxide anion conductor series. Since the MNb(PO{sub 4}){sub 3} solids possess a considerable high ion conducting behavior, promising applications such as chemical sensors for environmental gas detection and rechargeable batteries are highly expected.

Imanaka, N.; Itaya, M.; Ueda, T.; Adachi, G. [Department of Applied Chemistry, Faculty of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2002-12-02

24

NASICON-type Na3V2(PO43  

Directory of Open Access Journals (Sweden)

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

25

RbSn2(PO4)3, a NASICON-type phosphate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 f...

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

2011-01-01

26

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2009-03-31

27

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

28

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

29

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

30

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

31

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

32

Local structure and redox energies of lithium phosphates with olivine- and Nasicon-like structures  

Science.gov (United States)

An experimental relationship between local structure and electrochemical properties is established for lithium metal phosphates LiMePO 4 (Me = Fe, Co, Mn), LiFeP 2O 7 and Li 3Fe 2(PO 4) 3 which crystallise with either the olivine-like or the Nasicon-like structure. Structural features of several lithium metal phosphates are investigated by a local probe such as the FTIR spectroscopy in order to explain the influence of either PO or PO covalent bonds on redox energies. The local cationic arrangement is also discussed with the aid of a molecular vibration model to figure out the strong covalent bonds within a PO complex for glassy Nasicon compounds.

Salah, A. Ait; Jozwiak, P.; Garbarczyk, J.; Benkhouja, K.; Zaghib, K.; Gendron, F.; Julien, C. M.

33

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

34

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

35

Elaboration et caracterisation structurale de nouveaux phosphates de cuivre de type nasicon  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Les phosphates de cuivre de type NASICON CuxM2(PO4)3 (x=0,5 pour Cu2+; x=1 pour Cu+) (M=Ti, Zr) sont des matériaux remarquables par leurs propriétés catalytiques et luminescentes. L'établissement de modèles rendant compte de ces propriétés à nécessité la localisation du cuivre et la connaissance précise de son environnement par diverses techniques complémentaires : EXAFS, diffraction de neutrons, RMN, microscopie électronique. Le caractère lacunaire de ces phosphates a permis l'...

Bussereau, Isabelle

1990-01-01

36

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Structures of NASICON glasses of the general formula AB(2)(PO4)(3), Where A = Li, Na or K and B = Fe, Ga, Ti, V or Nb, have been investigated using vibrational (IR and Raman) spectroscopies. Phosphate species appear to establish an equilibrium via a disproportionation reaction involving a dynamical bond-switching mechanism where both charge and bonds are conserved. B ions in the system acquire different coordinations to oxygens. Alkali ions cause absorptions due to cage vibrations. All the ob...

Rao, Kj; Sobha, Kc; Kumar, Sundeep

2001-01-01

37

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

38

A mixed-valence niobium phosphate with an empty Nasicon structure: Nb2(PO4)3  

International Nuclear Information System (INIS)

Niobium(IV) niobium(V) phosphate, Mr=470.73, trigonal, Ranti 3c, a=8.6974(7), c=22.123(2) A, V=1449.3(3) A3, Z=6, Dx=3.24 Mg m-3, ?(Mo K?)=0.71073 A, ?=2.824 mm-1, T=294 K, F(000)=223, R=0.0347 and wR=0.03706 for 435 observed reflections. The niobium has a mixed valence (IV)-(V). The framework is built up from NbO6 octahedra sharing corners with PO4 tetrahedra and belongs to the empty Nasicon-type structure. (orig.)

39

NASICON-type Na3V2(PO4)3  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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)...

Zatovsky, Igor V.

2010-01-01

40

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

 
 
 
 
41

Electrical Properties of NASICON-type Structured Li1.3Al0.3Ti1.7(PO4)3 Solid Electrolyte Prepared by 1,2-Propylene glycol-assisted Sol-gel Method  

Science.gov (United States)

Lithium-ion conductor Li1.3Al0.3Ti1.7(PO4)3 with an ultrapure NASICON-type phase is synthesized by a 1,2-propylene glycol (1,2-PG)-assisted sol-gel method and characterized by differential thermal analysis-thermo gravimetric analysis, X-ray diffraction, scanning electron microscopy, electrochemical impedance spectroscopy, and chronoamperometry test. Due to the use of 1,2-PG, a homogeneous and light yellow transparent precursor solution is obtained without the precipitation of Ti4+ and Al3+ with PO43-. Well crystallized Li1.3Al0.3Ti1.7(PO4)3 can be prepared at much lower temperatures from 850 °C to 950 °C within a shorter synthesis time compared with that prepared at a temperature above 1000 °C by a conventional solid-state reaction method. The lithium ionic conductivity of the sintered pellets is up to 0.3 mS/cm at 50 °C with an activation energy as low as 36.6 kJ/mol for the specimen pre-sintered at 700 °C and sintered at 850 °C. The high conductivity, good chemical stability and easy fabrication of the Li1.3Al0.3Ti1.7(PO4)3 provide a promising candidate as solid electrolyte for all-solid-state Li-ion rechargeable batteries.

Zhang, Lin-chao; Chen, Peng; Hu, Zhang; Chen, Chun-hua

2012-12-01

42

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

43

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

44

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

45

Characterization of NASICON-type Na solid electrolyte ceramics by impedance spectroscopy  

Science.gov (United States)

Na solid electrolytes are cheaper than the ones of Li and could be of interest to apply in secondary batteries and gas sensors. In the present work, the NASICON-type Na1.3Ti1.7Al0.3(PO4)3 compound has been synthesized by Pechini method and the phase purity of the compound was confirmed by XRD. Ceramics of the compound were prepared in several different sintering temperatures and the morphology of the samples was examined by SEM. The investigation of the electrical properties was performed in 10 Hz to 3 ? 109 Hz and 300-500 K frequency and temperature ranges by means of impedance spectroscopy. The impedance spectra were analyzed and observed dispersions were related to microstructure of the ceramics.

Kazakevi?ius, E.; Kežionis, A.; Žukauskait?, L.; Barré, M.; Šalkus, T.; Orliukas, A.

2014-08-01

46

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

47

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

48

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

49

A New Nasicon-Type Phosphate Co 0.5Ti 2(PO 4) 3: I. Elaboration, Optical and Magnetic Properties  

Science.gov (United States)

A new cobalt titanium monophosphate has been prepared by low temperature method. It crystallizes with the Nasicon-type structure. The indexation of the X-ray diffraction pattern is consistent with the Roverline3or the R32 space groups. The atomic arrangement is a three-dimensional framework formed by PO 4tetrahedra sharing corners with TiO 6octahedra. Co 2+is located in half of the antiprism M(1) sites in a centered ( Roverline3) or off- centered ( R32) position. The optical, EPR and magnetic data can account for a pure ionic Co-O bond.

Olazcuaga, R.; Dance, J. M.; Le Flem, G.; Derouet, J.; Beaury, L.; Porcher, P.; El Bouari, A.; El Jazouli, A.

1999-03-01

50

Phase transitions and ionic mobility in LiHf{sub 2}(PO{sub 4}) with NASICON structure  

Energy Technology Data Exchange (ETDEWEB)

The authors report a first order phase transition in LiHf{sub 2}(PO{sub 4}){sub 3}. The phase transition is observed to be reversible. This substance has as NASICON structure (Na SuperIonic CONductors), with Li substituted for Na. The phase transformation occurs near 0{degrees}C, and is accompanied by an abrupt change in the ionic mobility.

Paris, M.A.; Martinez-Juarez, A.; Iglesias, J.E. [Instituto de Ciencia de Materiales de Madrid (Spain)] [and others

1997-06-01

51

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 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 t...

Amp Ric Hatert, Fr Amp D.

2009-01-01

52

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.

53

?-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

54

Structure and properties of NASICON synthesized by two different zirconium salts  

Science.gov (United States)

ZrOCl2·8H2O and ZrO(NO3)2·2H2O were used respectively to synthesize a NASICON solid electrolyte by a sol-gel method. The structure and properties of two samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and electrochemical impedance spectroscopy (EIS). The crystal structure was investigated by the Rietveld refinement. It is found that both the samples contain a monoclinic C2/ c phase as the main conductive phase with the lattice parameters of a=1.56312 nm, b=0.90784 nm and c=0.92203 nm, though a small amount of rhombohedral phase is also detected in the final product. The sample synthesized by ZrO(NO3)2·2H2O contains more monoclinic phase (89.48wt%) than that synthesized by ZrOCl2·8H2O (74.91wt%). As expected, the ionic conductivity of the latter is higher than that of the former; however, the activation energy of the latter (0.37 eV) is slightly higher than that of the former (0.35 eV).

Dang, Heng-yao; Guo, Xing-min; Huang, Yong-ping; Rong, Jiang-qi

2012-08-01

55

Structure and conductivity of the NASICON analog Na3SC2(PO4)3  

International Nuclear Information System (INIS)

Neutron and x-ray diffraction data of Na3SC2(PO4)3 are presented that show the transition from an ordinary-conducting, high temperature phase to a still higher temperature, superionic conducting phase. There are at least four polymorphic modifications. At room temperature, the refined neutron diffraction data confirm the Cc space group reported by Efremov and Kalinin but with a = 16.0449(24), b = 8.9225(15), c = 9.0656(13)A, #betta# = 126.918(21), R/sub weighted pattern/ = 17.5%, and R/sub expected/ = 7%. Between 250C and 640C, a second polymorph appears. The structure is monoclinic but has not yet been refined. At 640C, a third polymorph C appears. It is rhombohedral R3c. Using hexagonal axes, a = 8.9273(2), c = 22.3668A, R/sub wp/ = 6.28% and R/sub e/ = 3.83% at 1000C. At 1660C, the high temperature polymorph D appears. It is the superconducting phase of NASICON(Sc). It, too, is rhombohedral R3c with a = 8.9274(1), c = 22.5493(6)A, R/sub wp/ = 5.81% and R/sub e/ = 3.87% at 2250C. The diffraction data are correlated with ionic conductivity measurements as a function of temperature

56

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, Frédéric

2009-01-01

57

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

58

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)

59

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

60

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

 
 
 
 
61

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

62

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)

63

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

64

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

Science.gov (United States)

Li2NaV2(PO4)3 has been prepared in the rhombohedral NASICON structure via ion exchange from Na3V2(PO4)3. As a lithium-insertion cathode material, Li2NaV2(PO4)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

65

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

66

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

67

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

68

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.)

69

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)

70

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

71

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 spectroscopy confirmed the enhanced condu

72

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)

73

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

74

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

75

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

76

Ion conductor Na4Hf2Ge3O12 (nasicon): hydrothermal crystallization and crystal structure  

International Nuclear Information System (INIS)

Hydrothermal crystallization of Na, Hf - germanates is investigated within NaOH-HfO2-GeO2-H2O system at T = 600 deg C. Crystal structure of Na4Hf2Ge3O12 ion conductor with hexagonal cell parameters: a = 9.202, c = 22.407 A, Z = 6, sp.gr. R3c, R = 0.051, 1303 reflections - is determined by means of X-ray structure analysis. Analysis of structure features of MT-fragmework and Na - sublattices in NanM2T3O13 compounds (n = 1-4, M = Zr, Hf, T = Ge, Si, P) is conducted

77

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

78

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

79

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

80

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

 
 
 
 
81

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

82

Structure and conductivity of the NASICON analog Na/sub 3/SC/sub 2/(PO/sub 4/)/sub 3/  

Energy Technology Data Exchange (ETDEWEB)

Neutron and x-ray diffraction data of Na/sub 3/SC/sub 2/(PO/sub 4/)/sub 3/ are presented that show the transition from an ordinary-conducting, high temperature phase to a still higher temperature, superionic conducting phase. There are at least four polymorphic modifications. At room temperature, the refined neutron diffraction data confirm the Cc space group reported by Efremov and Kalinin but with a = 16.0449(24), b = 8.9225(15), c = 9.0656(13)A, ..beta.. = 126.918(21), R/sub weighted pattern/ = 17.5%, and R/sub expected/ = 7%. Between 25/sup 0/C and 64/sup 0/C, a second polymorph appears. The structure is monoclinic but has not yet been refined. At 64/sup 0/C, a third polymorph C appears. It is rhombohedral R3c. Using hexagonal axes, a = 8.9273(2), c = 22.3668A, R/sub wp/ = 6.28% and R/sub e/ = 3.83% at 100/sup 0/C. At 166/sup 0/C, the high temperature polymorph D appears. It is the superconducting phase of NASICON(Sc). It, too, is rhombohedral R3c with a = 8.9274(1), c = 22.5493(6)A, R/sub wp/ = 5.81% and R/sub e/ = 3.87% at 225/sup 0/C. The diffraction data are correlated with ionic conductivity measurements as a function of temperature.

Susman, S.; Delbecq, C.J.; Brun, T.O.; Prince, E.

1982-01-01

83

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

84

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 structu 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.

85

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

86

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

87

Pulsed laser deposition of nasicon thin films  

Science.gov (United States)

We have deposited NASICON ( Na Super Ionic CONductor) films of thicknesses ranging from 100 to 600 nm, by Pulsed Laser Deposition (PLD), on SiO 2/Si substrates. The deposition rates varied from 6 × 10 -3 to 0.08 nm/pulse depending on the conditions employed. XPS measurements show that all elements are transferred from the target to the substrate and that the thin film composition is very close to that of the target. Film morphology depends upon the laser energy density at the target. Films deposited at about 2 J/cm 2 show a rough surface and a columnar structure. At lower energy density (400 mj/cm 2), a smoother surface is obtained. Electrical measurements show good ionic conductivity, and that the films are suitable for the fabrication of electrochemical gas sensors.

Izquierdo, R.; Hanus, F.; Lang, Th.; Ivanov, D.; Meunier, M.; Laude, L.; Currie, J. F.; Yelon, A.

1996-04-01

88

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

89

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

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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 symmet...

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

2012-01-01

90

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

91

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 samp...

Fuentes, R. O.; Marques, F. M. B.; Franco, J. I.

1999-01-01

92

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

93

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

94

Synthesis, structure and characterisation of Fe 0.50Ti 2(PO 4) 3: A new material with Nasicon-like structure  

Science.gov (United States)

A new iron titanyl phosphate Fe 0.50Ti 2(PO 4) 3 was synthesized by both solid-state reaction and Cu 2+-Fe 2+ ion exchange method. The material was then characterized by X-ray diffraction, Mössbauer, 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¯, with a=8.511(1) Å and c=20.985(3) Å, V=1316.45(3) Å 3 and Z=6. The structure, which is compared to that of Mn 0.50Ti 2(PO 4) 3 is built up from [TiO 6] octahedra and [PO 4] tetrahedra which are linked by corner sharing along the c-axis. Fe 2+ 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¯. These results were supported by the Mössbauer studies that showed the presence of one Fe 2+ 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 Fe 2+ ions.

Benmokhtar, S.; El Jazouli, A.; Aatiq, A.; Chaminade, J. P.; Gravereau, P.; Wattiaux, A.; Fournès, L.; Grenier, J. C.

2007-07-01

95

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

96

A New Nasicon-Type Phosphate:Co 0.5Ti 2(PO 4) 3II. Simulation of Optical and Magnetic Properties  

Science.gov (United States)

The optical (energy level scheme) and magnetic properties (paramagnetic susceptibility as a function of the temperature and gvalues) of the polycrystalline Co 0.5Ti 2(PO 4) 3were simultaneously reproduced by use of a crystal field theory involving a set of Fk, ?, free ion, and Bkqcrystal field parameters. The crystal field parameters calculated from the structure are in fair agreement with the experimental ones and permit us to assign R32 as the space group of the crystal structure.

Derouet, J.; Beaury, L.; Porcher, P.; Olazcuaga, R.; Dance, J. M.; Le Flem, G.; El Bouari, A.; El Jazouli, A.

1999-03-01

97

FT-IR and FT-Raman study of Nasicon type phosphates, ASnFe(PO 4) 3 [A = Na 2, Ca, Cd  

Science.gov (United States)

FT-Raman and FT-IR spectra of ASnFe(PO 4) 3 [A = Na 2, Ca, Cd] were recorded and analyzed. The bands were assigned in terms of the vibrational group frequencies of SnO 6 octahedral and PO 4 tetrahedral. The spectral analysis shows that the symmetry of corner shared octahedral (SnO 6) and the tetrahedral (PO 4) are lowered from their free ion symmetry state. The presence of Fe 3+ ions disrupts the S-N-O-S-N chain in the structure. This causes distortion of SnO 6 and PO 4 in the structure of all the compounds. Also it is seen that there are two distinct PO 4 tetrahedra of different P-O bond lengths. One of these tetrahedra is linearly distorted in all the title compounds. The PO 4 frequencies and bond lengths are calculated theoretically and are in agreement with the experimental values. The presence of PO 4 polyanion in the structure can reduce the redox energy and hence reduce the metal oxygen covalency strength in the structure.

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

2011-01-01

98

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.)

99

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

100

NASICON-related Na3.4Mn0.4Fe1.6(PO43  

Directory of Open Access Journals (Sweden)

Full Text Available The solid solution, sodium [iron(III/manganese(II] tris(orthophosphate, Na3.4Mn0.4Fe1.6(PO43, was obtained using a flux method. Its crystal structure is related to that of NASICON-type compounds. The [(Mn/Fe2(PO43] framework is built up from an (Mn/FeO6 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.

Nikolay S. Slobodyanik

2012-07-01

 
 
 
 
101

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

102

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

Directory of Open Access Journals (Sweden)

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

103

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

104

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

105

A Mixed {alpha}/{beta} Superstructure in NASICON Ionic Conductors: Neutron Diffraction Study of Li  

Energy Technology Data Exchange (ETDEWEB)

The lithium conductors Li{sub 2}FeTi(PO{sub 4}){sub 3} and Li{sub 2}FeZr(PO{sub 4}){sub 3}, synthesized by solid-state reaction and characterized by X-ray powder diffractometry, were studied structurally at room temperature by neutron powder diffraction at high resolution (HRPD, ISIS Facility, U.K.). By trial-and-error and Rietveld refinements (R{sub p}=0.111, R(F{sup 2})=0.112), the first compound (orthorhombic Pbca, Z=8; a=8.5515(1), b=8.6229(1), c=23.9116(3) {angstrom}) was shown to have a complex superstructure sharing features of both the {alpha} and {beta} NASICON-type phases of LiZr{sub 2}(PO{sub 4}){sub 3}. Four (001) layers of PO{sub 4} and (Fe, Ti)O{sub 6} polyhedra are present per unit-cell, and they are related both by -1 inversion centers ({alpha} structure) and by a glide planes ({beta} structure). Ti{sup 4+} and Fe{sup 3+} order in the two interlayer regions, respectively. Owing to the structure complexity, only half of the lithium atoms could be refined in tetrahedral coordination with < Li-O > =1.99 {angstrom}. Li{sub 2}FeZr(PO{sub 4}){sub 3} (orthorhombic Pbna, Z=4; a=8.70559(8), b=8.78572(9), c=12.2202(1) {angstrom}) proved to be similar to {beta}-LiZr2(PO4)3; however, by Fourier synthesis and Rietveld refinement (R{sub p}=0.0618, R(F{sup 2})=0.0574) Li was located in a fully ordered tetrahedral configuration with < Li-O >=2.01 {angstrom}, instead of being disordered as in the phase of LiZr{sub 2}(PO{sub 4}){sub 3}.

Catti, Michele

2001-02-01

106

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

107

Restrictions to obtain NASICON by a ceramic route  

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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 st...

Fuentes, R. O.; Lamas, D. G.; Ferna?ndez Rapp, M. E.; Figueiredo, F. M.; Frade, J. R.; Marques, F. M. B.; Franco, J. I.

2004-01-01

108

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

109

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

110

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

111

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

112

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

113

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

114

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

115

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

116

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

117

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

118

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

119

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

120

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

 
 
 
 
121

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

122

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

123

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

124

A Mixed ?/ ? Superstructure in NASICON Ionic Conductors: Neutron Diffraction Study of Li 2FeTi(PO 4) 3 and Li 2FeZr(PO 4) 3  

Science.gov (United States)

The lithium conductors Li2FeTi(PO4)3 and Li2FeZr(PO4)3, synthesized by solid-state reaction and characterized by X-ray powder diffractometry, were studied structurally at room temperature by neutron powder diffraction at high resolution (HRPD, ISIS Facility, U.K.). By trial-and-error and Rietveld refinements (Rp=0.111, R(F2)=0.112), the first compound (orthorhombic Pbca, Z=8; a=8.5515(1), b=8.6229(1), c=23.9116(3) Å) was shown to have a complex superstructure sharing features of both the ? and ? NASICON-type phases of LiZr2(PO4)3. Four (001) layers of PO4 and (Fe, Ti)O6 polyhedra are present per unit-cell, and they are related both by overline1 inversion centers (? structure) and by a glide planes (? structure). Ti4+ and Fe3+ order in the two interlayer regions, respectively. Owing to the structure complexity, only half of the lithium atoms could be refined in tetrahedral coordination with =1.99 Å. Li2FeZr(PO4)3 (orthorhombic Pbna, Z=4; a=8.70559(8), b=8.78572(9), c=12.2202(1) Å) proved to be similar to ?-LiZr2(PO4)3; however, by Fourier synthesis and Rietveld refinement (Rp=0.0618, R(F2)=0.0574) Li was located in a fully ordered tetrahedral configuration with =2.01 Å, instead of being disordered as in the ? phase of LiZr2(PO4)3.

Catti, Michele

2001-02-01

125

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

126

Structural Integrity and Microstructure of NA^+ Conducting Ceramics  

Science.gov (United States)

Oxides with the general formula of Na1+x Zr2 Six P3-x O12 , known as Nasicon, are fast Na+ ion-conducting materials with important electrochemical applications and many functional properties, often attributed to their unique structural features. Comparative, in situ studies of the limits of structural integrity were performed for selected Nasicon materials, using synchrotron x-ray diffraction and diamond anvil cell technology. We show how different processing conditions produce crystalline structures with specific morphology. We discuss the bulk modulus, the compressibility and the influence of the volume fraction of primary and secondary crystalline phases on the overall Nasicon structural integrity.

Lipinska, Kristina; Kalita, Patricia; Hemmers, Oliver; Sinogeikin, Stanislav; Shebanova, Olga; Yang, Wenge; Mariotto, Gino

2010-03-01

127

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

128

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

129

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

130

Sintering of polycrystalline ionic conductors:. beta. ''-Al/sub 2/O/sub 3/ and NASICON  

Energy Technology Data Exchange (ETDEWEB)

The densification kinetics for both ..beta..''-alumina and NASICON are dramatically different. ..beta..''-Alumina sinters by a reactive liquid process whereas NASICON densifies by a solid state method. More importantly, a qualitative examination of particle and agglomerate distributions, phase composition, linear shrinkage analysis, and heating rate effects can result in a concise determination of sintering processes without recourse to more quantitative techniques. Such a simple procedural method should be a basis for any beginning investigative study into the densification mechanism of new multicomponent ceramic materials.

McEntire, B J; Miller, G R; Gordon, R S

1979-01-01

131

Sol–gel chemistry synthesis and DTA–TGA, XRPD, SIC and 7Li, 31P, 29Si MAS–NMR studies on the Li-NASICON Li3Zr2?ySi2?4yP1+4yO12 (0 ? y ? 0.5) system  

International Nuclear Information System (INIS)

Highlights: ? The samples of Li-NASICON were elaborated by sol–gel chemistry. ? The calcined temperatures of the studied samples were deduced from their thermograms. ? The recorded X-ray powder diffractograms were indexed in the rhombohedral system. ? The synthesized Li-NASICON materials are excellent lithium fast cation conductors. - Abstract: Five selected compounds of Li-NASICON, Li3Zr2?ySi2?4yP1+4yO12 (0 ? y ? 0.5), were synthesized by sol–gel chemistry in order to obtain pure polycrystalline powder and then analyzed by different physicochemical characterizations such as coupled DTA (differential thermal analysis)–TGA (thermogravimetric analysis), XRPD (X-ray powder diffraction), CIS (complex impedance spectroscopy) and MAS (magic angle spinning)–NMR (nuclear magnetic resonance). So the calcined temperature of each sample has been deduced from its corresponding DTA–TGA thermogram. However, the recorded X-ray powder diffractograms were indexed in the rhombohedral system with R3¯c space group which corresponds to the ideal structure of NASICON. Whereas, the complex impedance spectroscopy study showed that these Li-NASICON materials are excellent lithium fast cation conductors with total electric conductivity maximal value 1.97 × 10?3 S cm?1 at 293 K in the case of Li3Zr1.5P3O12. Furthermore, 7Lp>7Li, 31P and 29Si MAS–NMR spectroscopy study and DFT/B3LYP theoretical calculations of chemical shifts were performed to discuss the ambiguousness that exists between the resonance peak number in the experimental spectrum and the crystallographic site number relative to Li3Zr2Si2PO12.

132

Structural and vibrational studies of NaZr2(AsO4)3  

International Nuclear Information System (INIS)

The structure of NaZr2(AsO4)3, which belongs to the Nasicon-type family, was solved by the Rietveld method in the R3-barc space group, from X-ray powder diffraction data. The hexagonal unit cell parameters are ah=9.1518(2) A and ch=23.1097(4) A. The structure is formed by a three-dimensional network of AsO4 tetrahedra and ZrO6 octahedra sharing corners. Na atoms occupy totally the M1 site. Raman and infrared spectra were recorded and assignments of the As-O stretching and bending modes were made

133

Preparación cristaloquímica y comportamiento eléctrico de electrolitos sólidos de estequiometría NASICON  

Digital Repository Infrastructure Vision for European Research (DRIVER)

En el presente trabajo se ha llevado a cabo la preparación y la caracterización estructural y eléctrica de varias series de materiales de estequiometría NASICON, sistema ampliamente conocido por sus propiedades conductoras y adecuadas prestaciones en el campo de los electrolitos sólidos. Las síntesis se han realizado, en general, en estado sólido por el método cerámico, caracterizándose los compuestos obtenidos empleando muy diversas técnicas como difracción de rayo...

Maldonado Manso, Mari?a Pilar

2004-01-01

134

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)

135

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

136

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

137

Spin ordering between sub-lattices in nasicon Li3Fe2(PO4)3 measured by Mössbauer spectroscopy  

Science.gov (United States)

The chemical stability and conductivity of nasicon-structured ?-Li3Fe2(PO4)3 make it a possible candidate for a cathode material in Li-battery. The x-ray diffraction pattern of Li3Fe2(PO4)3 showed the monoclinic structure with space group of P21/n. In the zero-field-cooled (ZFC) curve, the magnetization remained constant while the temperature was increased up to the splitting temperature (TS = 11 K) of two sub-lattices, indicating the antiferromagnetic behavior below TS. Magnetization curves of both ZFC and FC from 4.2 to 295 K showed ferrimagnetic behavior below the Néel temperature (TN = 29.5 K). We observed the change in the slope of the temperature-dependent Hhf curve at TS. These results suggest that the change in the spin ordering in Li3Fe2(PO4)3 is originated from the difference in hyperfine interactions between the localized Fe3+ magnetic ions at each of two sub-lattices. The spectra of Li3Fe2(PO4)3 under applied magnetic field of 5 T exhibit the magnetic phase transition around TS, indicating antiferromagnetic behavior below TS and ferrimagnetic behavior between TS and TN.

Kim, Hee Seung; Kim, Chul Sung

2013-05-01

138

Interferometer-type structures for guided atoms  

International Nuclear Information System (INIS)

We experimentally demonstrate interferometer-type guiding structures for neutral atoms based on dipole potentials created by microfabricated optical systems. As a central element we use an array of atom waveguides being formed by focusing a red-detuned laser beam with an array of cylindrical microlenses. Combining two of these arrays, we realize X-shaped beam splitters and more complex systems like the geometries for Mach-Zehnder and Michelson-type interferometers for atoms

139

Interferometer-Type Structures for Guided Atoms  

CERN Document Server

We experimentally demonstrate interferometer-type guiding structures for neutral atoms based on dipole potentials created by micro-fabricated optical systems. As a central element we use an array of atom waveguides being formed by focusing a red-detuned laser beam with an array of cylindrical microlenses. Combining two of these arrays, we realize X-shaped beam splitters and more complex systems like the geometries for Mach-Zehnder and Michelson-type interferometers for atoms.

Dumke, R; Volk, M; Ertmer, W; Birkl, G

2002-01-01

140

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

 
 
 
 
141

Relations conductivité/microstructure dans des céramiques composites superconducteur (NASICON)/verre isolant  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Des céramiques composites à base de superconducteur ionique NASICON (Na 3Zr2Si2PO12) et de verre peu conducteur (Na2Zr4Si16P8O 61) ont été élaborées suivant une filière « SOL-GEL » par frittage à basse température. Les microstructures obtenues ont été analysées par microscopie électronique et l'inter-réaction entre les deux phases a été étudiée par microanalyse Raman. La conductivité des composites a été analysée par spectrométrie d'impédances complexes pour diverses...

Colomban, Ph

1987-01-01

142

Structure of superionic Ag3Se2(PO4)3 crystals produced from the Na3Sc2(PO4)3 single crystals by ion exchange  

International Nuclear Information System (INIS)

Ion exchange of Na+ for Ag+ was conducted to indicate conduction channels in the frame of Na3Sc2(PO4)3 crystals. X-ray diffraction study of prepared monocrystals showed, that the former sodium positions (6b) was divided into two positions Ag(1) and Ag(2), and Na(2) (18e) position was transformed into two common positions Ag(3) and Ag(4). Distribution of silver ions over new positions enables to conclude that the least ones together with positions of Na+ ions indicate clearly the trajectory of ion motion in all structures of NASICON type. 8 refs.; 1 fig.; 1 tab

143

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

144

Elaboration by a soft chemistry process of zirconium-deficient NaSICON compositions; Elaboration par chimie douce de compositions NaSICON deficitaires en zirconium  

Energy Technology Data Exchange (ETDEWEB)

This paper deals with the preparation of a family of ionic conductor ceramics known as NaSICON (Na Super Ionic CONductor) and with their characterization. For this family constituted of silicon, sodium, phosphorus and zirconium, an original process is proposed to obtain pure ceramics. Precursors are sodium nitrate, zirconyl nitrate, ammonium phosphate, tetra-ethoxy-silane (TEOS), nitric acid and ethanol. New compositions unknown in literature (Na{sub 3.2}Zr{sub 1.9}Si{sub 1.5}P{sub 1.5}O{sub 12} and Na{sub 2.8}Zr{sub 1.8}Si{sub 1.1}P{sub 1.9}O{sub 12}) were studied. The thermal decomposition of the precursors was performed with a slow heating rate. It was studied by ADT-ATG and X-ray diffraction. The thermal decomposition leads to the oxide at 750 deg C, which was characterized by X-ray diffraction. These materials can be used in the automotive industry as chemical sensors for CO{sub 2}, H{sub 2} or SO{sub 2}. (authors)

Favotto, C.; Roubin, M. [Toulon Univ., Materiaux a Finalites Specifiques, UPRES 1356, LPCM3, Faculte des Sciences et Techniques, 83 - La Garde (France)

2000-08-01

145

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

2009-02-20

146

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

147

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)

148

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

149

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

150

Homotopy type and A?-group structure  

International Nuclear Information System (INIS)

The aim of the paper is to define and study algebraic operations closely related to the group structure on the homotopy groups of topological spaces. These are certain many-place operations on the homotopy groups. The family of these operations induces an algebraic structure on the homotopy groups, which is called an A?-group structure by analogy with the A?-structures introduced by Stasheff

151

Characteristics of Thick Film CO2 Sensors Based on Nasicon Using Li2CO3-CaCO3 Auxiliary Phases  

Science.gov (United States)

Potentiometric devices were fabricated using a NASICON (Na1+xZr2SixP3-xO12) thick film and auxiliary layers. The powder of a precursor of NASICON with high purity was synthesized using the sol-gel method. Using the NASICON paste, an electrolyte was prepared on the alumina substrate through screen printing and then sintered at 1,000°C for 4 hours. In the present study, a series of Li2CO3-CaCO3 system was deposited on the Pt sensing electrode. Within a wide range of CO2 volume ratio concentration from 1,000 ppm to 10,000 ppm, the output of the sensor showed good electromotive force (EMF) response that was very close to the theoretical value. The device to which Li2CO3-CaCO3 (1:2) was attached showed good sensing properties at low temperatures.

Kim, Han Ji; Shim, Han Byel; Choi, Jung Woon; Yoo, Kwang Soo; Kim, Shin Do

2006-06-01

152

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

153

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

154

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

155

Lithium Ion Materials for Energy Applications: Structural Properties from Neutron Diffraction  

Science.gov (United States)

Cathode materials and solid electrolytes to be used in lithium batteries require a high ionic mobility of Li^+ species in their crystal structures. This in turn depends on the order-disorder state of lithium and on its bonding environment. Neutron diffraction is the choice technique to study the structural features of polycrystalline lithium materials that control their performance in ion transport processes. The basic principles of ionic mobility in solids and of the Rietveld refinement methods for neutron diffraction data are briefly reviewed. Then two important families of lithium conductors are selected from the literature and thoroughly discussed: the LLTO perovskite-type Li_xLa_{2/3-x/3}TiO_3 system and the Li_{1+x}Me_2(PO_4)_3 Nasicon phases. Accurate neutron diffraction determinations of the corresponding crystal structures have been shown to provide a considerable insight into the mechanisms of Li^+ ion transfer in such materials.

Catti, Michele

156

Sol-gel chemistry synthesis and DTA-TGA, XRPD, SIC and {sup 7}Li, {sup 31}P, {sup 29}Si MAS-NMR studies on the Li-NASICON Li{sub 3}Zr{sub 2-y}Si{sub 2-4y}P{sub 1+4y}O{sub 12} (0 Less-Than-Or-Slanted-Equal-To y Less-Than-Or-Slanted-Equal-To 0.5) system  

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer The samples of Li-NASICON were elaborated by sol-gel chemistry. Black-Right-Pointing-Pointer The calcined temperatures of the studied samples were deduced from their thermograms. Black-Right-Pointing-Pointer The recorded X-ray powder diffractograms were indexed in the rhombohedral system. Black-Right-Pointing-Pointer The synthesized Li-NASICON materials are excellent lithium fast cation conductors. - Abstract: Five selected compounds of Li-NASICON, Li{sub 3}Zr{sub 2-y}Si{sub 2-4y}P{sub 1+4y}O{sub 12} (0 Less-Than-Or-Slanted-Equal-To y Less-Than-Or-Slanted-Equal-To 0.5), were synthesized by sol-gel chemistry in order to obtain pure polycrystalline powder and then analyzed by different physicochemical characterizations such as coupled DTA (differential thermal analysis)-TGA (thermogravimetric analysis), XRPD (X-ray powder diffraction), CIS (complex impedance spectroscopy) and MAS (magic angle spinning)-NMR (nuclear magnetic resonance). So the calcined temperature of each sample has been deduced from its corresponding DTA-TGA thermogram. However, the recorded X-ray powder diffractograms were indexed in the rhombohedral system with R3{sup Macron }c space group which corresponds to the ideal structure of NASICON. Whereas, the complex impedance spectroscopy study showed that these Li-NASICON materials are excellent lithium fast cation conductors with total electric conductivity maximal value 1.97 Multiplication-Sign 10{sup -3} S cm{sup -1} at 293 K in the case of Li{sub 3}Zr{sub 1.5}P{sub 3}O{sub 12}. Furthermore, {sup 7}Li, {sup 31}P and {sup 29}Si MAS-NMR spectroscopy study and DFT/B3LYP theoretical calculations of chemical shifts were performed to discuss the ambiguousness that exists between the resonance peak number in the experimental spectrum and the crystallographic site number relative to Li{sub 3}Zr{sub 2}Si{sub 2}PO{sub 12}.

Belam, W., E-mail: WahidBelam@yahoo.fr [Chemistry Department, Bizerta Science Faculty, 7021 Jarzouna, Bizerta (Tunisia)

2013-02-25

157

Types and Functions of Coastal Structures  

DEFF Research Database (Denmark)

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

158

Reactor structure of LMFBR type reactor  

International Nuclear Information System (INIS)

In an LMFBR type reactor, a flow channel hole for connecting an intermediate plenum and a low pressure plenum and a pipe for connecting a lower plenum and a cover gas space above the free coolant level are disposed in a reactor core vessel, and a liquid level indicator is disposed at the upper end of the pipe. If a leak preceding type crack is caused in a reactor core support cone partitioning the intermediate plenum and the lower plenum, coolants leak and flow out of the cracked portion to the lower plenum. Since leaked and flown coolants raise the liquid level in the pipe which keeps the height identical with that of the free coolant level during usual operation, the elevation of the liquid level is detected by the liquid level indicator, and failure of the reactor core support cone is prevented. Further, the reactor can be shutdown safely before it leads to accidents by using the liquid level elevation detection signal sent from the liquid indicator as a reactor shutdown signal. (N.H.)

159

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

160

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

 
 
 
 
161

Co-linear spin configurations in corundum-type structures  

International Nuclear Information System (INIS)

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

162

Polarization of herringbone structure in type II bursts  

International Nuclear Information System (INIS)

Herringbone Type II bursts were first described by Roberts (1959). These bursts are distinguished by their unusual structure - rib-like features (herringbone) extending on either side of a Type II backbone. The authors report the observed polarization characteristics of 16 events during 1977/1978 (supplemented by results obtained from radio-heliograph observations of six earlier events). (Auth.)

163

Homogeneous pseudo-Riemannian structures of linear type  

Science.gov (United States)

This article is partly a survey and partly a research paper on homogeneous pseudo-Riemannian structures of linear type. In the Riemannian case, these structures furnish characterisations of real, complex and quaternionic hyperbolic spaces. In the Lorentzian case, a related class gives characterisations of singular homogeneous plane waves.

Batat, Wafaa; Gadea, Pedro M.; Oubiña, José A.

2011-03-01

164

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

165

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

International Nuclear Information System (INIS)

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

166

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

167

Mating type loci inFusarium: structure and function.  

Science.gov (United States)

Sex in fungi is regulated by highly dissimilar mating type loci named idiomorphs. The genus Fusarium harbours both sexual as well as esexual species and each appears to contain one or the other idiomorph. The structure of these loci is highly conserved, suggesting a cryptic sexual cycle in these socalled asexual species. Alternatively, idiomorphs could regulate additional hitherto unrecognized biological processes. Such processes could be elucidated by expression profiling using mutants disrupted in their mating type loci. PMID:23605502

Waalwijk, C; Keszthelyi, A; van der Lee, T; Jeney, A; de Vries, I; Kerenyi, Z; Mendes, O; Hornok, L

2006-03-01

168

Transient electromagnetic and structure analysis of BELlows type vacuum vessels  

International Nuclear Information System (INIS)

The authors performed transient electromagnetic and structure analysis of vacuum vessels, which employ bellows for one-turn resistance. BELTEM (Code for BELlows type vacuum vessel in Transient Electromagnetic and Mechanical analysis) system was developed in this work. The authors emphasize, in the present paper, that several modes of the electromagnetic force are induced in the bellows due to its corrugation and they have a significant influence on the structure design of vacuum vessel

169

Transitions between type A flake, type D flake, and coral graphite eutectic structures in cast irons  

Science.gov (United States)

Directional solidification experiments were used to measure the transition velocities between the type A and coral eutectic structures in high-purity cast irons and between the type A and type D eutectic structures in S and Te doped cast irons. Introduction of O into the gas atmosphere was found to have little effect on the A ? D transition velocities in S doped alloys, but it produced a strong reduction in the A ? coral transition velocities in high-purity irons. Transmission electron micros-copy revealed interesting variations in the defect structures of the graphite in the flake irons vs the type of flake (A or D) and the type of doping element. Scanning Auger microscopy demonstrated that both S and Te segregate to the iron/graphite interface. In the S doped alloys, type A flakes are generally covered with a monolayer of S with patches of 0 in the form of iron oxide having a thickness on the order of 2 nm. A series of experiments, including examination of fracture surfaces at the quenched solid/liquid growth front, have shown that S segregates to the iron/graphite interfaces from the liquid at the growth front, but O forms at these interfaces during the cooldown. These results are discussed in relation to current models of eutectic growth in cast irons.

Park, J. S.; Verhoeven, J. D.

1996-09-01

170

Metal atom incorporation studies on the phases with NZP structure: square NbTiP3O12  

International Nuclear Information System (INIS)

A wide variety of electropositive elements of the periodic table can be inserted into the vacant sites in the host framework structure of hexagonal NbTiP3O12 (an analog of nasicon) to give rise to isostructural phases. Synthesis, characterization, and preliminary data on the structure, IR spectra, and electrical resistivity are presented. Possible areas for further exploration are delineated

171

Homogeneous pseudo-Riemannian structures of linear type  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Homogeneous pseudo-Riemannian structures of linear type are reviewed and studied. In the Riemannian case, they furnish characterisations of the real, complex and quaternionic hyperbolic spaces. In the Lorentzian case, a related class gives characterisations of singular homogeneous plane waves.

Batat, Wafaa; Gadea, Pedro M.; Oubin?a, Jose Antonio

2010-01-01

172

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

173

Structural and micromechanical characterization of type I collagen gels.  

Science.gov (United States)

In this paper we report a study where we use a novel optical tweezers technique to measure the local viscoelastic properties of type I collagen solutions spanning the sol-to-gel transition. We use phase contrast optical microscopy to reveal dense and sparse regions of the rigid fibril networks, and find that the spatial variations in the mechanical properties of the collagen gels closely follow the structural properties. Within the dense phase of the connected network in the gel samples, there are regions that exhibit drastically different viscoelastic properties. Within the sparse regions of the gel samples, no evidence of elasticity is found. In type I collagen gels, we find a high degree of structural inhomogeneity. The inhomogeneity in the structural properties of collagen gels and the corresponding viscoelastic properties provide benchmark measurements for the behavior of desirable biological materials, or tissue equivalents. PMID:19880123

Latinovic, Olga; Hough, Lawrence A; Daniel Ou-Yang, H

2010-02-10

174

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

175

Extended, regular HI structures around early-type galaxies  

CERN Document Server

We discuss the morphology and kinematics of the HI of a sample of 30 southern gas-rich early-type galaxies selected from the HI Parkes All-Sky Survey (HIPASS). This is the largest collection of high-resolution HI data of a homogeneously selected sample. Given the sensitivity of HIPASS, these galaxies represent the most HI-rich early-type galaxies. In two-thirds of the galaxies, we find the HI to be in a large, regular disk- or ring-like structure that in some cases is strongly warped. In the remaining cases we find the HI distributed in irregular tails or clouds offset from the galaxy. The giant, regular HI structures can be up to ~200 kpc in diameter and contain up to 10^10 M_sun of HI. The incidence of irregular HI structures appears to be somewhat higher in elliptical galaxies, but the large, regular structures are observed in both elliptical and S0 galaxies and are not strictly connected to the presence of a stellar disk. If these two types of galaxies are the result of different formation paths, this is ...

Oosterloo, T; Sadler, E M; Van der Hulst, J M; Serra, P

2007-01-01

176

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

177

Magnetic mirror structure for testing shell-type quadrupole coils  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-10-01

178

Structure of unsteady sprays injected from pintle-type nozzles  

Energy Technology Data Exchange (ETDEWEB)

The temporal and spatial characteristics of the transient diesel spray injected from a pintle-type nozzle into the atmosphere were investigated by phase Doppler anemometry and its structure visualised by high speed photography. The droplet velocities and sizes were quantified near the nozzle exit and the degree of fuel atomisation deduced from the fractal dimension estimated from the droplets size distribution. High frequency periodic structures were identified on the surface of the transient spray and attributed to aerodynamic interactions between the injected fuel and surrounding air.

Arcoumanis, C.; Paal, G.; Whitelaw, J.H.

1992-07-23

179

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

180

Structure of type II dehydroquinase from Pseudomonas aeruginosa.  

Science.gov (United States)

Pseudomonas aeruginosa causes opportunistic infections and is resistant to most antibiotics. Ongoing efforts to generate much-needed new antibiotics include targeting enzymes that are vital for P. aeruginosa but are absent in mammals. One such enzyme, type II dehydroquinase (DHQase), catalyzes the interconversion of 3-dehydroquinate and 3-dehydroshikimate, a necessary step in the shikimate pathway. This step is vital for the proper synthesis of phenylalanine, tryptophan, tyrosine and other aromatic metabolites. The recombinant expression, purification and crystal structure of catalytically active DHQase from P. aeruginosa (PaDHQase) are presented. Cubic crystals belonging to space group F23, with unit-cell parameters a=b=c=125.39?Å, were obtained by vapor diffusion in sitting drops and the structure was refined to an R factor of 16% at 1.74?Å resolution. PaDHQase is a prototypical type II DHQase with the classical flavodoxin-like ?/? topology. PMID:25372814

Reiling, Scott; Kelleher, Alan; Matsumoto, Monica M; Robinson, Gonteria; Asojo, Oluwatoyin A

2014-11-01

 
 
 
 
181

Universal Structure and a Categorical Framework for Type Theory  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis investigates the possibility of a computer checked language for categories with extra structure; the language is to describe objects and morphisms of those categories and to reason about them. We do so first by developing an abstract analysis of representability. This is followed by the investigation of a categorical framework for studying type theory. Our computer checked language therefore allows us to reason about the semantics of programming languages and models of logics. ...

Takeyama, Makoto

1995-01-01

182

Structural and functional properties of C-type starches.  

Science.gov (United States)

This study investigated the structural and functional properties of C-type starches from pea seeds, faba bean seeds, yam rhizomes and water chestnut corms. These starches were mostly oval in shape with significantly different sizes and contents of amylose, damaged starch and phosphorus. Pea, faba bean and water chestnut starches had central hila, and yam starch had eccentric hilum. Water chestnut and yam starches had higher amylopectin short and long chain, respectively. Water chestnut and faba bean starches showed CA-type crystallinities, and pea and yam starches had C-type crystallinities. Water chestnut starch had the highest swelling power, granule swelling and pasting viscosity, lowest gelatinization temperatures and enthalpy. Faba bean starch had the lowest pasting viscosity, whereas yam starch had the highest gelatinization temperatures. Water chestnut and yam starches possessed significantly higher and lower susceptibility to acid and enzyme hydrolysis, the highest and lowest RDS contents, and the lowest and highest RS contents, respectively. PMID:24299776

Cai, Jinwen; Cai, Canhui; Man, Jianmin; Zhou, Weidong; Wei, Cunxu

2014-01-30

183

Babel Fortran 2003 Binding for Structured Data Types  

Energy Technology Data Exchange (ETDEWEB)

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

Muszala, S; Epperly, T; Wang, N

2008-05-02

184

Structural integrity of reactor system for top entry type FBR  

International Nuclear Information System (INIS)

The paper presents the structural design and evaluation of components for the top entry loop type reactor, the demonstration fast breeder reactor of Japan. The reactor is characterized in that a number of components are suspended from the roof deck and the free sodium surface moves when the reactor is started and shut down. The structural integrity of components of the reactor system were evaluated according to DDS under consideration of the reactor outlet temperature being set to 550 deg. C and the strict seismic conditions in Japan. All components were shown to meet the requirements of DDS. Detailed description is given on the aseismic analysis of the reactor system and evaluation of the structural integrity near the free sodium surface of the reactor vessel, which are typical examples for the evaluation. (author)

185

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

186

Synthesis and characterization of a NaSICON series with general formula Na 2.8Zr 2-ySi 1.8-4yP 1.2+4yO 12 (0? y?0.45)  

Science.gov (United States)

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 Na 2.8Zr 2-ySi 1.8-4yP 1.2+4yO 12 with 0? y?0.45. The various compositions were synthesized by produced using the sol-gel method. The electric properties of these compositions were carried out by impedance spectroscopy. The results highlight the good conductivity of the Na 2.8Zr 1.775Si 0.9P 2.1O 12 composition.

Essoumhi, A.; Favotto, C.; Mansori, M.; Satre, P.

2004-12-01

187

Structure and Biophysics of Type III Secretion in Bacteria  

Science.gov (United States)

Many plant and animal bacterial pathogens assemble a needle-like nanomachine, the type III secretion system (T3SS), to inject virulence proteins directly into eukaryotic cells to initiate infection. The ability of bacteria to inject effectors into host cells is essential for infection, survival, and pathogenesis for many Gram-negative bacteria, including Salmonella, Escherichia, Shigella, Yersinia, Pseudomonas, and Chlamydia spp. These pathogens are responsible for a wide variety of diseases, such as typhoid fever, large-scale food-borne illnesses, dysentery, bubonic plague, secondary hospital infections, and sexually transmitted diseases. The T3SS consists of structural and nonstructural proteins. The structural proteins assemble the needle apparatus, which consists of a membrane-embedded basal structure, an external needle that protrudes from the bacterial surface, and a tip complex that caps the needle. Upon host cell contact, a translocon is assembled between the needle tip complex and the host cell, serving as a gateway for translocation of effector proteins by creating a pore in the host cell membrane. Following delivery into the host cytoplasm, effectors initiate and maintain infection by manipulating host cell biology, such as cell signaling, secretory trafficking, cytoskeletal dynamics, and the inflammatory response. Finally, chaperones serve as regulators of secretion by sequestering effectors and some structural proteins within the bacterial cytoplasm. This review will focus on the latest developments and future challenges concerning the structure and biophysics of the needle apparatus. PMID:23521714

Chatterjee, Srirupa; Chaudhury, Sukanya; McShan, Andrew C.; Kaur, Kawaljit; De Guzman, Roberto N.

2013-01-01

188

[Studies on a new type structure OELD with interinserting interface].  

Science.gov (United States)

A new type organic electroluminescent device with interinserting interface was fabricated. The basic structure of the device is ITO/NPB/Alq3/Al. By tailor-made template, the two interinserting interfaces were fabricated with NPB/Alq3 and Alq3/Al, respectively. The charge distribution on the interface and the electric field distribution in the organic layer were changed by introducing interinserting interfaces, thus the electron injection was improved, and the balance of the number of the electrons and holes at the interface was obtained. Therefore, the formation probability of exciton was enhanced and the leakage current was reduced. Compared to the traditional two-layer structure devices, the interinserting structure device has lower turn-on voltage and higher luminous efficiency. The driving-voltage of the interinserting structure OELD decreased while the brightness increased with the increase in the number of the interinsertion. As the current density increased, all the devices with interinserting interface showed high optical-electrical stability. The turn-on voltage of the device e is 3 V, and was made using the three slots template. At the current density of 54 mA x cm(-2), the device e gets its maximum efficiency, which is 34% higher than the traditional structure device a. PMID:20210139

Zhang, Zhi-Qiang; Hao, Yu-Ying; Meng, Wei-Xin; Fan, Wen-Hao; Wang, Hua; Xu, Bing-She

2009-12-01

189

Identification of type-II inhibitors using kinase structures.  

Science.gov (United States)

Spleen tyrosine kinase is a non-receptor tyrosine kinase, overactivation of which is thought to contribute to autoimmune diseases as well as allergy and asthma. Protein kinases have a highly conserved ATP binding site, thus making challenging the design of selective small molecule inhibitors. It has been well documented that some protein kinases can be stabilized in their inactive conformations (Type-II inhibitors). Herein, we describe a protein structure/ligand-based approach to successfully identify ligands that bind to novel conformations of spleen tyrosine kinase. By utilizing kinase protein crystal structures both in the public domain (RCSB) and within Pfizer's protein crystal database, we report the discovery of the first spleen tyrosine kinase Type-II ligands. Compounds 1 and 3 were found to bind to the DFG-out conformation of spleen tyrosine kinase, while compound 2 binds to a DFG-in, C-Helix-out conformation. In this instance, the C-helix moved significantly to create a large hydrophobic pocket rarely seen in kinase protein crystal structures. PMID:22759374

Lovering, Frank; McDonald, Joseph; Whitlock, Gavin A; Glossop, Paul A; Phillips, Chris; Bent, Andrew; Sabnis, Yogesh; Ryan, Mark; Fitz, Lori; Lee, Julie; Chang, Jeanne S; Han, Seungil; Kurumbail, Ravi; Thorarensen, Atli

2012-11-01

190

New family of superionic conductors Na sub 8-x+y-z M sup z P sub 2 O sub 9-x F sub x+y (M = Ca, Al, Cr, Fe, Ti; 0 <= x,y <= 1): crystal structure, lattice dynamics, transport properties  

Energy Technology Data Exchange (ETDEWEB)

A review of data on electrophysical, structural, optical and thermodynamical studies of new superionics belonging to the Na{sub 8-z-x+y}M{sup z}P{sub 2}O{sub 9-x}F{sub x+y} family (M = Ca, Al, Fe, Ti). A high ionic conductivity (about 10{sup -1}-10{sup -4}S cm{sup -1} at 573 K) is observed for all the materials under investigation. It is pointed out that there is no rigid skeleton in the crystal structure of the materials, contrary to the Na-superionic -conductor (NASICON)-type superionics. Another feature of these crystals is the constant temperature of the superionic phase transition which lies in a temperature range from 520 to 540 K depending on the M cations used. (orig.).

Sigaryov, S.E. (Inst. of Crystallography, USSR Academy of Sciences, Moscow (USSR))

1992-03-30

191

Structural analysis of a new type lightweight optical mirror blank  

Science.gov (United States)

To reduce the cost and increase the feasibility of the astronomical optical telescope, modern large optical telescope is normally required to be as light as possible. Therefore lightweight mirror is always pursued by large telescopes development. In this paper, a new type lightweight optical mirror blank, the evaluation of its technical feasibility and the reduction of cost are introduced. For the purpose of applying active optics with this lightweight mirror blank, the structural analysis, thermal analysis and optical performance simulation by the finite element method have been presented.

Li, Yeping; Cui, Xiangqun; Hu, Ningsheng

2010-07-01

192

Structure and evolution of W UMa-type systems  

Science.gov (United States)

We summarize and discuss our recent works on the structure and evolution of low-mass W UMa-type contact binary stars. Three conclusions are given as followings: (1) The energy transfer is taken place in the radiative region of common envelope of W UMa systems; (2) The magnetic activity level of W UMa systems is weaker than that of non-contact binaries or rapid-rotating single stars; (3) The evolutionary outcome of W UMa systems might be the rapid-rotating single stars, and an average lifetime is derived to be about 7 Gyr for W UMa systems.

Li, Lifang; Zhang, Fenghui; Han, Zhanwen; Jiang, Dengkai; Jiang, Tianyu

2008-10-01

193

Type IIB Flux Vacua at Large Complex Structure  

CERN Document Server

We study models of stabilization near large complex structure in type IIB O3/O7 flux compactifications. We consider a special family of examples with a single nonvanishing Yukawa coupling in the large complex structure limit, which allows us to study all possible, stable tree-level vacua very explicitly. We find that, by tuning fluxes, both supersymmetric and nonsupersymmetric vacua can be realized at almost any point in the large complex structure moduli space of one-, two-, and three-parameter models. We also consider the effect of stringy corrections on tree-level vacua. We argue quite generally that in a certain regime both supersymmetric and nonsupersymmetric tree-level vacua can serve as consistent, controllable foundations for full stabilization beyond tree level (including Kahler moduli), leading to AdS or dS cosmological constants. We show how to achieve this regime in our models. Finally, we discuss some implications of minimizing at tree level the no-scale form of the scalar potential, versus other...

Dimofte, Tudor Dan

2008-01-01

194

Wave structures excited in compressible Petschek-type magnetic reconnection  

Science.gov (United States)

We present a method to analyze the wave and shock structures arising from Petschek-type magnetic reconnection Based on a time-dependent analytical approach developed by Heyn and Semenov 1996 and Semenov et al 2004 we calculate the perturbations caused by a delta function-shaped reconnection magnetic field which allows to achieve a representation of the plasma variables in the form of Green s functions Different configurations for the initial conditions are considered In the case of symmetric antiparallel magnetic fields and symmetric plasma density the well-known structure of an Alfvén discontinuity a fast volume wave a slow shock a slow wave and a tube wave occurs In the case of asymmetric antiparallel magnetic fields additionally surface waves are found We also discuss the case of symmetric antiparallel magnetic fields and asymmetric densities which leads to a faster propagation in the lower half plane causing side waves forming a Mach cone in the upper half plane Complex effects like anisotropic propagation characteristics intrinsic wave coupling and the generation of different non-linear and linear wave modes in a finite beta plasma are retained The temporal evolution of these wave and shock structures is shown

Penz, T.; Semenov, V. S.; Heyn, M. F.; Ivanova, V. V.; Ivanov, I. B.; Biernat, H. K.

195

Seeing double: crystal structures of the type I TNF receptor.  

Science.gov (United States)

The crystal structure of the extracellular domain of the type I tumor necrosis factor receptor (sTNF-R1) has been determined to 2.25 A at pH 7.5. We have also solved the structure of sTNF-R1 at pH 3.7. sTNF-R1 is an elongated molecule consisting of a linear combination of four cysteine-rich motifs. Interestingly, the crystal structure reveals two distinct dimers of the receptor. One dimer is formed by a parallel arrangement of receptors, the other by an antiparallel arrangement of receptors. In the parallel arrangement of the receptors, the tumor necrosis factor (TNF) binding face of the receptor is completely exposed to solvent. However, in the antiparallel arrangement, the TNF binding face is intimately involved in the dimer interactions. Details of these recognition surfaces are discussed. Both these dimer interactions bury substantial surface area, comprise polar and apolar contact surfaces and have complimentary recognition surfaces. Thus these interactions are typical of genuine protein-protein interactions, rather than crystal packing contacts. These dimers may function to inhibit signal transduction in the absence of TNF or in the case of the parallel dimer, promote clustering of TNF/TNF receptor complexes on the cell surface. PMID:8877801

Naismith, J H; Brandhuber, B J; Devine, T Q; Sprang, S R

1996-01-01

196

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.

197

Structural Characterization of Novel Pseudomonas aeruginosa Type IV Pilins  

Energy Technology Data Exchange (ETDEWEB)

Pseudomonas aeruginosa type IV pili, composed of PilA subunits, are used for attachment and twitching motility on surfaces. P. aeruginosa strains express one of five phylogenetically distinct PilA proteins, four of which are associated with accessory proteins that are involved either in pilin posttranslational modification or in modulation of pilus retraction dynamics. Full understanding of pilin diversity is crucial for the development of a broadly protective pilus-based vaccine. Here, we report the 1.6-{angstrom} X-ray crystal structure of an N-terminally truncated form of the novel PilA from strain Pa110594 (group V), which represents the first non-group II pilin structure solved. Although it maintains the typical T4a pilin fold, with a long N-terminal {alpha}-helix and four-stranded antiparallel {beta}-sheet connected to the C-terminus by a disulfide-bonded loop, the presence of an extra helix in the {alpha}{beta}-loop and a disulfide-bonded loop with helical character gives the structure T4b pilin characteristics. Despite the presence of T4b features, the structure of PilA from strain Pa110594 is most similar to the Neisseria gonorrhoeae pilin and is also predicted to assemble into a fiber similar to the GC pilus, based on our comparative pilus modeling. Interactions between surface-exposed areas of the pilin are suggested to contribute to pilus fiber stability. The non-synonymous sequence changes between group III and V pilins are clustered in the same surface-exposed areas, possibly having an effect on accessory protein interactions. However, based on our high-confidence model of group III PilA{sub PA14}, compensatory changes allow for maintenance of a similar shape.

Nguyen, Y.; Jackson, S; Aidoo, F; Junop, M; Burrows, L

2010-01-01

198

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.)

199

Creep behaviour and structural changes of 316 type stainless steels  

International Nuclear Information System (INIS)

The creep behaviour of 316 type stainless steel used in LMFBR reactors, in the vicinity of 0.5 Tsub(m) under low stress is strongly dependent on the long term structural stability of the alloy. Anomalous creep stages develop on the creep curve and can be related to the various stages of precipitation. The final distribution of precipitates is altered by the creep stress. The macroscopic creep parameters, such as the apparent activation energy and stress exponent, take on unusually high values which are typical of strong interactions between creep and precipitation. The anomalously low values of the dislocation density measured in deformed samples confirm the solute drag effect on dislocations during creep

200

Structural insight into the type-II mitochondrial NADH dehydrogenases.  

Science.gov (United States)

The single-component type-II NADH dehydrogenases (NDH-2s) serve as alternatives to the multisubunit respiratory complex?I (type-I NADH dehydrogenase (NDH-1), also called NADH:ubiquinone oxidoreductase; EC 1.6.5.3) in catalysing electron transfer from NADH to ubiquinone in the mitochondrial respiratory chain. The yeast NDH-2 (Ndi1) oxidizes NADH on the matrix side and reduces ubiquinone to maintain mitochondrial NADH/NAD(+) homeostasis. Ndi1 is a potential therapeutic agent for human diseases caused by complex?I defects, particularly Parkinson's disease, because its expression restores the mitochondrial activity in animals with complex?I deficiency. NDH-2s in pathogenic microorganisms are viable targets for new antibiotics. Here we solve the crystal structures of Ndi1 in its substrate-free, NADH-, ubiquinone- and NADH-ubiquinone-bound states, to help understand the catalytic mechanism of NDH-2s. We find that Ndi1 homodimerization through its carboxy-terminal domain is critical for its catalytic activity and membrane targeting. The structures reveal two ubiquinone-binding sites (UQ(I) and UQ(II)) in Ndi1. NADH and UQ(I) can bind to Ndi1 simultaneously to form a substrate-protein complex. We propose that UQ(I) interacts with FAD to act as an intermediate for electron transfer, and that NADH transfers electrons through this FAD-UQ(I) complex to UQ(II). Together our data reveal the regulatory and catalytic mechanisms of Ndi1 and may facilitate the development or targeting of NDH-2s for potential therapeutic applications. PMID:23086143

Feng, Yue; Li, Wenfei; Li, Jian; Wang, Jiawei; Ge, Jingpeng; Xu, Duo; Liu, Yanjing; Wu, Kaiqi; Zeng, Qingyin; Wu, Jia-Wei; Tian, Changlin; Zhou, Bing; Yang, Maojun

2012-11-15

 
 
 
 
201

Perovskite-type oxides - Oxygen electrocatalysis and bulk structure  

Science.gov (United States)

Perovskite type oxides were considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. Perovskite stability and electrocatalytic activity are studied along with possible relationships of the latter with the bulk solid state properties. A series of compounds of the type LaFe(x)Ni1(-x)O3 was used as a model system to gain information on the possible relationships between surface catalytic activity and bulk structure. Hydrogen peroxide decomposition rate constants were measured for these compounds. Ex situ Mossbauer effect spectroscopy (MES), and magnetic susceptibility measurements were used to study the solid state properties. X ray photoelectron spectroscopy (XPS) was used to examine the surface. MES has indicated the presence of a paramagnetic to magnetically ordered phase transition for values of x between 0.4 and 0.5. A correlation was found between the values of the MES isomer shift and the catalytic activity for peroxide decomposition. Thus, the catalytic activity can be correlated to the d-electron density for the transition metal cations.

Carbonio, R. E.; Fierro, C.; Tryk, D.; Scherson, D.; Yeager, E.

1988-01-01

202

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

Energy Technology Data Exchange (ETDEWEB)

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

Adachi, Takafumi (Institute for Molecular Science, Okazaki, Aichi (Japan)); Shirotani, Ichimin; Shimomura, Osamu

1999-04-01

203

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

International Nuclear Information System (INIS)

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

204

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

205

Type IIA orientifolds on SU(2)-structure manifolds  

International Nuclear Information System (INIS)

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

206

Type of structure of men body engaged in baseball  

Directory of Open Access Journals (Sweden)

Full Text Available 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 of Piechaczka. General fat in a percentage ratio to mass of body is expected on the formula of Brozka i Keys. 20 indexes are in general complication certain. On the basis of their setting of norms the type of structure of body of examinee is set. A comparative group was made by the students of the Warsaw polytechnic institute. The members of masculine collapsible command of Poland differ on baseball, foremost, by the high indexes of diameter of forearm, widths of elbow, surface and mass of body, diameter of shin.

Jagiello Wladyslaw.

2012-11-01

207

Types of tectonic structures favourable for metamorphogenetic uranium deposit formation  

International Nuclear Information System (INIS)

Structures controlling the location of uranium metamorphogenetic deposits are identified: regional structures, determining the location of ore zones and ore areas; structures of ore fields; structures of ore deposits; structures of ore masses; intraore structures. All the structures arose before ore deposition and they served as ways of solution penetration, resulting in preore metasomatic alterations. Along them tectonic replacements were renewed, accompanied by infiltration of ore-bearing solutions and ore deposition. Methods for the study of metamorphogenetic deposit structures are enumerated

208

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

209

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

210

Structure of the type IX group B Streptococcus capsular polysaccharide and its evolutionary relationship with types V and VII.  

Science.gov (United States)

The Group B Streptococcus capsular polysaccharide type IX was isolated and purified, and the structure of its repeating unit was determined. Type IX capsule ? 4)[NeupNAc-?-(2 ? 3)-Galp-?-(1 ? 4)-GlcpNAc-?-(1 ? 6)]-?-GlcpNAc-(1 ? 4)-?-Galp-(1 ? 4)-?-Glcp-(1 ? appears most similar to types VII and V, although it contains two GlcpNAc residues. Genetic analysis identified differences in cpsM, cpsO, and cpsI gene sequences as responsible for the differentiation between the three capsular polysaccharide types, leading us to hypothesize that type V emerged from a recombination event in a type IX background. PMID:24990951

Berti, Francesco; Campisi, Edmondo; Toniolo, Chiara; Morelli, Laura; Crotti, Stefano; Rosini, Roberto; Romano, Maria Rosaria; Pinto, Vittoria; Brogioni, Barbara; Torricelli, Giulia; Janulczyk, Robert; Grandi, Guido; Margarit, Immaculada

2014-08-22

211

Structures related to the ?-tungsten or Cr3Si structure type  

International Nuclear Information System (INIS)

Traditional crystalographic operations, such as translation, rotation and reflection, and intergrowth are used to show how several structures, among them the tetrahedrally close-packed, can be accurately derived from the ?-tungsten structure type. Examples are Zr4Al3, Fe2B, Mo3CoSi, Ga2Mg5, GaMg, Ga,?- and ?- V3S, W2CoB2, CeAl, W5Si3, the sigma phase, the Friauf-Laves phases, the ? phase, the P and M phases, the (Co0 57Si0 43(3V2 phase, the chi phase, and the ? phase. 53 references, 26 figures, 6 tables

212

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

213

Structural studies concerning joining areas of tin-base antifriction alloy with the Charpy type structure  

International Nuclear Information System (INIS)

The distribution of alloying constituents and the structural components observed in the contact areas between a tin-base antifriction alloy (Charpy type stpucture) and a steel case are investigated by methods of electron microscopy, X-ray spectroscopy and X-ray diffraction. The results are correlated with the ultrasonic signals from areas of various degree of adherence and allow an accurate explanation and interpretation of these signals. (authors)

214

Structure-activity studies of aplysiatoxin-type tumor promoters.  

Science.gov (United States)

The cellular activities and responses of aplysiatoxin in vitro and in vivo are very similar to those of the diterpene 12-O-tetradecanoylphorbol-13-acetate (TPA) and the indole aklaloids teleocidin B and lyngbyatoxin A. Even though aplysiatoxin, TPA, and teleocidin B are chemically and structurally quite distinct from one another, all three compounds produce essentially the same plethora of biological effects by apparently binding to the same receptor on the cell membrane, the so-called phorboid receptor. Several aplysiatoxin-type compounds have been studied in three test systems for evaluating potential tumor-promoting activity, viz. mouse ear skin for irritation, murine dorsal skin for the induction of ornithine decarboxylase (ODC) activity, and an epidermal particulate fraction of dorsal mouse skin for the inhibition of specific binding of [3H]-TPA. Some of the compounds were tested in a 30-week two-step carcinogenesis experiment in mice. In most cases the results of the 30-week test correlated with the activities of the three preliminary tests. The overall study indicated that the hydroxyl groups on C-3, C-20, and C-30 are essential for maximum activity. Inspection of Dreiding models showed that the oxygens on C-27, C-3, and C-30 of aplysiatoxin are aligned with the oxygens on C-3, C-4, and C-20 of TPA, respectively. The latter oxygens are in functional groups that are known to be necessary for the high activity of TPA. PMID:6243065

Moore, R E

1983-01-01

215

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

216

Bismuth zinc vanadate, BiZn2VO6: New crystal structure type and electronic structure  

Science.gov (United States)

We report a combined experimental and computational study of the crystal structure and electronic properties of bismuth zinc vanadate, BiZn2VO6, known for its visible light photocatalytic activity. The crystal structure has been solved from laboratory powder X-ray diffraction data using the repeated minimisations from random starting values method. BiZn2VO6 adopts a new structure type, based on the following building blocks: corner- and edge-sharing ZnO4 tetrahedra, ZnO6 octahedra and VO4 tetrahedra, and Bi2O12 dimers. It is the only known member of the BiM2AO6 (M=Pb, Ca, Cd, Mn, Zn, Mg, Cu; A=V, P, As) family which does not appear to be structurally closely related to others. The electronic structure of BiZn2VO6, calculated by DFT methods, shows that it is an indirect gap semiconductor with a calculated band gap of 1.6 eV, which compares favourably to the experimentally measured value of 2.4 eV.

Eliziario Nunes, Sayonara; Wang, Chun-Hai; So, Karwei; Evans, John S. O.; Evans, Ivana Radosavljevi?

2015-02-01

217

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

218

Fine structure analysis of type-specific and type-common antigenic sites of herpes simplex virus glycoprotein D.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The fine structure of the antigenic determinants of herpes simplex virus type 1 and 2 glycoprotein D (gD) was analyzed to determine whether structural differences underlie the differential immunogenicity of these glycoproteins. A region common to herpes simplex virus type 1 and 2 gD (amino acid residues 11 to 19) and two sites specific for herpes simplex virus type 2 gD (one determined by proline at position 7, the other determined by asparagine at position 21) were localized within the N-ter...

Dietzschold, B.; Eisenberg, R. J.; Ponce Leon, M.; Golub, E.; Hudecz, F.; Varrichio, A.; Cohen, G. H.

1984-01-01

219

Muscle fibre types of fishes; structural and functional specialization  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Muscles of fishes are active in a variety of movements that differ in velocity, duration and excursion length. To investigate how muscles meet the, often conflicting, demands imposed upon them by these movements, the fibre type composition of several muscles was determined. The ultrastructural and contractile properties of some of the obtained fibre types were measured and compared with their functional activity.In head muscles as well as in body muscles of perch and carp, four types of muscl...

Akster, H. A.

1984-01-01

220

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

 
 
 
 
221

Quadrant-type X-band single-cell structure for high gradient tests  

International Nuclear Information System (INIS)

We are building a new high-gradient X-band (11.424 GHz) testbench, called “Shield-B,” for basic studies to establish a acceleration technology with 100MV/m or higher, where various single-cell structures are to be tested. We focus on quadrant-type structures, on which no surface currents associated with magnetic fields flow across cell-to-cell junctions unlike disk-type structures. In this study, we propose a quadrant-type X-band single-cell structure with a heavy damped structure by waveguides, overcoming its issues. (author)

222

English Verb-Particle Constructions: Two Types, Two Structures.  

Science.gov (United States)

This paper proposes that resultative verb-particle constructions (VPCs) have an underlyingly different structure from idiomatic VPCs; both structures differ from the Small Clause analysis of R. Kayne (1985) et al and the verb-particle complex analysis of K. Johnson (1991). Empirical support for the new proposal comes from anaphor deletion facts…

Zoerner, Ed

1996-01-01

223

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

224

Structure and sorption properties of a zeolite-templated carbon with the EMT structure type.  

Science.gov (United States)

An ordered microporous carbon material was prepared by the nanocasting process using the EMC-2 zeolite (EMT structure type) as a hard template. X-ray diffraction (XRD) and transmission electron microscopy (TEM) revealed long-range ordering in the material that resulted from the negative replication of the host template. The carbon porous network replicating the zeolite structure was modeled by overlapped spherical voids with diameters determined from the XRD pattern that displayed up to six distinct peaks. The surface delimiting the 3D interconnected porosity of the solid has a complex morphology. The pore size distribution calculated from the XRD-derived structural model is characterized by a maximum at 1.04 nm related to the long-range-ordered microporous network. Complementary studies by immersion calorimetry revealed that most of the porosity was characterized by a size above 1.5 nm. These porous features were compared to data resulting from classical analysis (DR, DFT, BET, etc.) of the N2 (77 K) and CO2 (low and high pressure, 273 K) physisorption isotherms. The limitations of these approaches are discussed in light of the pore size distribution consistently determined by XRD and immersion calorimetry measurements. PMID:24359449

Parmentier, Julien; Gaslain, Fabrice O M; Ersen, Ovidiu; Centeno, Teresa A; Solovyov, Leonid A

2014-01-14

225

Semiconducting half-Heusler and LiGaGe structure type compounds  

Energy Technology Data Exchange (ETDEWEB)

Compounds with LiAlSi (half-Heusler) and LiGaGe structure types have been investigated by means of band structure calculations. The LiAlSi structure type is known as the half-Heusler structure type, whereas LiGaGe is a closely related hexagonal variant. A remarkable feature of some XYZ half-Heusler compounds with 8 and 18 valence electrons is, that despite being composed of only metallic elements, they are semiconductors. More than 100 semiconducting compounds within these structure types are known. LiGaGe compounds have an additional degree of freedom, namely the degree of puckering of the layers. These compounds can become semiconducting at a certain degree of puckering. Half-metallic behavior is rarely found in this structure type. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Casper, Frederick; Felser, Claudia [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg University, Mainz (Germany); Seshadri, Ram [Materials Department and Materials Research Laboratory, University of California, Santa Barbara, CA (United States)

2009-05-15

226

Cage structure materials for n-type transparent conducting oxides  

Science.gov (United States)

The transport properties of mayenite-based materials, Ca12Al 14O33, were investigated. Systems studied included H-doped/UV-irradiated Ca12Al14O33, Ca(12- x)MgxAl14O 33 (x = 0.1, 0.3, 0.5, 0.8, 1) and Ca12Al(14- x)Six O33+x2 (x = 1, 2, 3, 4). The as-prepared Ca12Al14O 33 exhibited a room temperature electronic conductivity on the order of 10-10 S/cm, and a high temperature (600°C) ionic conductivity approximately an order of magnitude less than that of yttria-stabilized zirconia. After H-doping/UV-irradiation Ca12Al14O33 displayed an electronic conductivity of 0.3 S/cm at room temperature rising reversibly to 1 S/cm at ˜130°. Beyond this temperature hydrogen loss is evident and with it the carrier concentration decreases. Below room temperature the system exhibits a variable range hopping and a small polaron hopping above room temperature. H-treated/UV-irradiated Mg-substituted compounds present inferior electrical properties compared to Ca12Al14O 33, with conductivities in the range of 0.15-0.28 S/cm at room temperature. Magnesium is suggested to be responsible for the overall decrease in conductivity, as theoretical calculations suggest that it acts as a blocking agent. On the other hand, the proton-implanted/UV-irradiated Ca12Al(14-x)Si x O33+x2 shows an increase in conductivity, consistent with the aliovalent substitution. Conductivities of 0.68 S/cm were found for the higher Si-substitution level (in H-implanted specimens) suggesting that the amount of free oxygen ions inside the structural cavities plays a significant role in determining the electrical properties of the compound. Results are in good agreement with density functional calculations performed on all these systems. The highly reduced [Ca24Al28O62] +4+4e- system presents a wide range of conductivities dependent on the reduction time. The maximum value obtained was 1400 S/cm for Ca12Al14O33 reduced in the presence of titanium shot for 4 days of treatment. A reversal in the sign of the thermopower was observed for the high conductivity samples. The temperature dependance of the conductivity shows degenerate behavior above room temperature, and a linear relation between the resistivity and temperature below room temperature. This degenerate behavior suggests an insulator-to-metal conversion, however, it can also be explained by the small polaron mechanism observed for the H-treated/UV-activated mayenite-based samples. Ultimately, mobility data will define the type of mechanism governing this compound's behavior.

Bertoni, Mariana Ines

227

Microfibrillar structure of type I collagen in situ  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The fibrous collagens are ubiquitous in animals and form the structural basis of all mammalian connective tissues, including those of the heart, vasculature, skin, cornea, bones, and tendons. However, in comparison with what is known of their production, turnover and physiological structure, very little is understood regarding the three-dimensional arrangement of collagen molecules in naturally occurring fibrils. This knowledge may provide insight into key biological processes such as fibrill...

Orgel, Joseph P. R. O.; Irving, Thomas C.; Miller, Andrew; Wess, Tim J.

2006-01-01

228

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Igor Zelenko

2009-01-01

229

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

230

Tb2Ni2Mg3: a new structure type derived from the Ru3Al2B2 type  

International Nuclear Information System (INIS)

Single crystals of diterbium dinickel trimagnesium, Tb2Ni2Mg3, were synthesized from the elements by induction melting. The novel compound crystallizes in the space group Cmmm with one Mg atom of site symmetry mmm and the Tb, Ni and other Mg atom in m2m positions. This ternary compound represents a new structure type that is derived from Ru3Al2B2 by way of Wyckoff site distribution. The twolayer structure of Tb2Ni2Mg3 is a new representative of a homologous linear structure series of general formula R'k+nX2nR''200m+k based on structural fragments of the ?-Fe, CsCl and AlB2 structure types. The Tb atoms in the structure are enclosed in 17-vertex polyhedra, while rhombododecahedra and distorted rhombododecahedra surround the Mg atoms, and equatorially tricapped trigonal prisms form around the Ni atoms. All interatomic distances indicate metallic type bonding. (orig.)

231

Structures of the Mating-Type Loci of Cordyceps takaomontana  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Yokoyama, Eiji; Yamagishi, Kenzo; Hara, Akira

2003-01-01

232

Electrical conductivity and Hf 4+ ion substitution range in NaSICON system  

Science.gov (United States)

In this paper, we present the synthesis and characterizations of NaSICON-type ionic conducting ceramics of the general formula Na 1+ xM 1.775Si x-0.9P 3.9- xO 12 with 1.8 ? x ? 2.2 and M = Zr or Hf. The effect of the total substitution of zirconium by hafnium on electric properties has been studied. The various compositions were prepared by using the sol-gel method and the synthesized precursors were characterized by coupled DTA-TG. The oxides obtained after pyrolysis of the precursors were identified by X-ray diffraction. A sintering study by thermodilatometry permits to select the best thermal cycle adapted to our ceramics. Furthermore, the electric conductivity of the sintered ceramic samples was characterized by complex impedance spectroscopy. These results show that ceramics containing Zr synthesized by soft method, present a higher total conductivity than those obtained in literature (to be around 10 -4 S cm -1). The total substitution of Zr by Hf still improves this conductivity for some compositions.

Essoumhi, A.; Favotto, C.; Mansori, M.; Ouzaouit, K.; Satre, P.

2007-03-01

233

TFS-Mode: GNU Emacs User-Interface für das Typed Feature Structures System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Das am Institut für maschinelle Sprachverarbeitung (IMS) der Universität Stuttgart entwickelte Typed Feature Structures (TFS) Grammatikentwicklungssystem [EZ90, Zaj92] ermöglicht die Implementierung und das Austesten von unifikationsbasierten Grammatiktheorien (wie z.B. LFG, HPSG). Dabei dienen typisierte Attribut-Wert-Strukturen (Typed Feature Structures) als universelle Datenstrukturen für die Kodierung grammatikalischen Wissens. Texteditoren sind zur Eingabe von Grammati...

Hoch, Edgar

1993-01-01

234

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

International Nuclear Information System (INIS)

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

235

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

236

The on axis coupled structure type RF gun  

International Nuclear Information System (INIS)

The fundamental design of this newly developed RF gun with a thermionic cathode is the ?/2 mode standing wave structure. It has two accelerating cells and a coupling cell located on the beam axis, a so-called on axis coupled structure (OCS). This structure offers a stable operation for high beam current, owing to high group velocity and wide bandwidth. It is important to reduce damage onto the cathode caused by back bombardment, especially for long macropulse operation, such as in an FEL injector. Back bombardment, as well as output beam profile was simulated by using the electromagnetic field analytical codes 'EMSYS'(2D) and 'MAFIA'(3D). The cavity shape was optimized to reduce back bombardment power without sacrificing beam emittance

237

The on axis coupled structure type RF gun  

CERN Document Server

The fundamental design of this newly developed RF gun with a thermionic cathode is the pi/2 mode standing wave structure. It has two accelerating cells and a coupling cell located on the beam axis, a so-called on axis coupled structure (OCS). This structure offers a stable operation for high beam current, owing to high group velocity and wide bandwidth. It is important to reduce damage onto the cathode caused by back bombardment, especially for long macropulse operation, such as in an FEL injector. Back bombardment, as well as output beam profile was simulated by using the electromagnetic field analytical codes 'EMSYS'(2D) and 'MAFIA'(3D). The cavity shape was optimized to reduce back bombardment power without sacrificing beam emittance.

Oda, F; Nakayama, A; Tanabe, E

1999-01-01

238

STRUCTURAL PHASE TRANSITION AND MAGNETISM OF Ni-As-TYPE TRANSITION METAL PNICTIDES  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Structural transformation of CoAs and NiAs from NiAs-type to MnP-type are studied microscopically. Electron-lattice matrix elements and generalized susceptibilities are calculated on the basis of electronic bands obtained by APW method. Band calculation of FeAs having MnP-type structure is made for non-magnetic state. Results are discussed in connection with magnetic ordering.

Motizuki, K.; Morifuji, M.

1988-01-01

239

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

240

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

 
 
 
 
241

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

242

Flow structure measurement by beam scan type LDV  

Science.gov (United States)

A new type of laser Doppler velocimeter called SLV (Scan-Type Laser-Doppier Velocimeter) which can measure the velocity field almost continuously and simultaneously has been developed and tested. The principle of the apparatus is to traverse the focal point of split laser beams by reflecting them with a rotating polygon mirror or an oscillating mirror which is driven (and controlled) by a stepping motor and to receive the scattered Doppler signals by a photomultiplier by focusing them through a cylindrical lens. The signals from the photomultiplier and the driving pulse of the stepping motor were transmitted to a persona] computer and processed on-line. Experiments on the oscillatory boundary layer, Kármán vortices, and vortex rings were carried out to check the performance.

Hino, M.; Nadaoka, K.; Kobayashi, T.; Hironaga, K.; Muramoto, T.

1987-05-01

243

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.

244

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Nandagopan, O. R.; Sameer Abdul Azeez; Nandakumar, C. G.

2013-01-01

245

On the origin of rare earth magnetostriction in compounds of perovskite-type structure  

Science.gov (United States)

It has been shown that a gigantic rare earth magnetostriction is possible in a perovskite-type structure as well as in a garnet structure. Numerical calculations of multipole moments of the rare earth ion have allowed us to predict the directions of maximum values of magnetostriction in dysprosium aluminate. Measurements confirm the highly anisotropic character of magnetostriction in rare earth compounds of perovskite-type structure and show that the rare earth magnetostriction of compounds with different structures (garnets, perovskites) is determined mainly by the rare earth ion and not by their structures.

Kolmakova, N. P.; Krynetskii, I. B.

1994-02-01

246

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

247

Fine-structure constant constraints on Bekenstein-type models  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Astrophysical tests of the stability of dimensionless fundamental couplings, such as the fine-structure constant $\\alpha$, are an area of much increased recent activity, following some indications of possible spacetime variations at the few parts per million level. Here we obtain updated constraints on the Bekenstein-Sandvik-Barrow-Magueijo model, which is arguably the simplest model allowing for $\\alpha$ variations. Recent accurate spectroscopic measurements allow us to imp...

Leal, P. M. M.; Martins, C. J. A. P.; Ventura, L. B.

2014-01-01

248

The structural stability of wild-type horse prion protein.  

Science.gov (United States)

Prion diseases (e.g. Creutzfeldt-Jakob disease (CJD), variant CJD (vCJD), Gerstmann-Straussler-Scheinker syndrome (GSS), Fatal Familial Insomnia (FFI) and Kuru in humans, scrapie in sheep, bovine spongiform encephalopathy (BSE or 'mad-cow' disease) and chronic wasting disease (CWD) in cattles) are invariably fatal and highly infectious neurodegenerative diseases affecting humans and animals. However, by now there have not been some effective therapeutic approaches or medications to treat all these prion diseases. Rabbits, dogs, and horses are the only mammalian species reported to be resistant to infection from prion diseases isolated from other species. Recently, the ?2-?2 loop has been reported to contribute to their protein structural stabilities. The author has found that rabbit prion protein has a strong salt bridge ASP177-ARG163 (like a taut bow string) keeping this loop linked. This paper confirms that this salt bridge also contributes to the structural stability of horse prion protein. Thus, the region of ?2-?2 loop might be a potential drug target region. Besides this very important salt bridge, other four important salt bridges GLU196-ARG156-HIS187, ARG156-ASP202 and GLU211-HIS177 are also found to greatly contribute to the structural stability of horse prion protein. Rich databases of salt bridges, hydrogen bonds and hydrophobic contacts for horse prion protein can be found in this paper. PMID:21875155

Zhang, Jiapu

2011-10-01

249

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

250

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

251

Fine-structure constant constraints on Bekenstein-type models  

CERN Document Server

Astrophysical tests of the stability of dimensionless fundamental couplings, such as the fine-structure constant $\\alpha$, are an area of much increased recent activity, following some indications of possible spacetime variations at the few parts per million level. Here we obtain updated constraints on the Bekenstein-Sandvik-Barrow-Magueijo model, which is arguably the simplest model allowing for $\\alpha$ variations. Recent accurate spectroscopic measurements allow us to improve previous constraints by about an order of magnitude. We briefly comment on the dependence of the results on the data sample, as well as on the improvements expected from future facilities.

Leal, P M M; Ventura, L B

2014-01-01

252

Fine-structure constant constraints on Bekenstein-type models  

Science.gov (United States)

Astrophysical tests of the stability of dimensionless fundamental couplings, such as the fine-structure constant ?, are an area of much increased recent activity, following some indications of possible spacetime variations at the few parts per million level. Here we obtain updated constraints on the Bekenstein-Sandvik-Barrow-Magueijo model, which is arguably the simplest model allowing for ? variations. Recent accurate spectroscopic measurements allow us to improve previous constraints by about an order of magnitude. We briefly comment on the dependence of the results on the data sample, as well as on the improvements expected from future facilities.

Leal, P. M. M.; Martins, C. J. A. P.; Ventura, L. B.

2014-07-01

253

The chemistry of fluorescent whitening agents. Major structural types.  

Science.gov (United States)

This gives a summary of those fluorescent whitening agents (FWAs) that have industrial importance. Firstly, a survey of the general physical and applicational properties is given, and then the chemistry of FWAs is dealt with. The FWAs are classified in six major structural classes: (A) stilbenes (B) coumarin and carbostyril compounds, (C) 1,3-DIPHENYL-2-PYRAZOLINES, (D) naphthalimides, (E) benzoxazolyl substitution products of conjugated systems, and (F) combined products of other heteroaromatics with ethylene or aromatic systems, owing to their methods of preparation and to their optical characteristics. PMID:776606

Gold, H

1975-01-01

254

Ferroelectric and ferroelastic domains in bronze type tunnel structures  

International Nuclear Information System (INIS)

This brief review serves to illustrate the capabilities of high-resolution electron microscopy (HREM) to reveal fine structures of a surprising variety of microstructural domains. Example include the hierarchy of chaotic states existing in the incommensurate room temperature phase of strontium barium niobate. HREM showed directly nature of the atoms (W,Nb) displacements responsible for the hexagonal component of the superstructures occurring throughout phase transitions of potassium niobium tungstate (PNT). The reciprocal lattice geometry of the commensurate superlattice phase of barium sodium niobate has been determined and a full structural model derived; thus the space group appears to be Im2a with orthorhombic cell parameters a=35.18Aangstroem, b=35.24Aangstroem, c=7.99 Aangstroem. Non-stoichiometric phases of PNT have orthorhombic superstructures and the microdiffraction analysis allowed possible orthorhombic space groups and unit cell parameters to be derived for the three phases. It is suggested that PNT may be considered as an alternative subject for non-linear laser technology. 20 figs., 9 figs

255

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

256

Type II compactifications on manifolds with SU(2) x SU(2) structure  

International Nuclear Information System (INIS)

We study compactifications of type II theories on SU(2) x SU(2) structure manifolds to six, five and four spacetime dimensions. We use the framework of generalized geometry to describe the NS-NS sector of such compactifications and derive the structure of their moduli spaces. We show that in contrast to SU(3) x SU(3) structure compactifications, there is no dynamical SU(2) x SU(2) structure interpolating between an SU(2) structure and an identity structure. Furthermore, we formulate type II compactifications on SU(2) x SU(2) structures in the context of exceptional generalized geometry which makes the U-duality group manifest and naturally incorporates the scalar degrees of freedom arising in the Ramond-Ramond sector. Via this formalism we derive the structure of the moduli spaces as it is expected from N = 4 supergravity.

257

[X-ray diffraction study of high hydrostatic pressure on crystalline structure of different type starches].  

Science.gov (United States)

Crystalline changes of different type starches after high hydrostatic pressure treated under 300, 450, 600 MPa were studied by X-ray diffraction. Waxy maize (A type, 100% amylopectin), hylon VII (B type, 30% amylopectin) and tapioca starch (C type, 83% amylopectin) were chosen. The results indicated that for waxy maize starch, annealing effect was observed at 300 MPa, disappearance of crystalline structure happened at 450 MPa and retrogradation at 600 MPa. The results proved that the granule under high hydrostatic pressure processing experiences "three development stages" including annealling effect, disappearance of crystalline structure and recrystalline after granule disintegration. PMID:23240443

Liu, Pei-Ling; Shen, Qun; Hu, Xiao-Song; Wu, Ji-Hong

2012-09-01

258

Characterisation of proton incorporation in perovskite-type structure  

International Nuclear Information System (INIS)

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

259

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)4)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.

260

Neurofibromatosis type 1 and type 2: review of the central nervous system and related structures.  

Science.gov (United States)

Although computed tomography (CT) provides a major imaging advance over conventional radiography and tomography in examining the whole body, the development of magnetic resonance (MR) imaging has proven to be an even greater breakthrough in diagnostic medical imaging. The anatomic detail demonstrated in a MR image is a representation of at least three physical properties of static-tissue: proton density, and T1 and T2 relaxation times. Intrinsic differences in proton density and, in particular, in proton relaxation times of tissues allow excellent image contrast between various normal structures and high sensitivity in detecting pathological states. This article discusses imaging features of neurofibromatosis, with particular emphasis on the potential of MR imaging. PMID:9071483

Inoue, Y; Nemoto, Y; Tashiro, T; Nakayama, K; Nakayama, T; Daikokuya, H

1997-01-01

 
 
 
 
261

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2014-01-01

262

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

Orlowski, Jerzy; Bujnicki, Janusz M.

2008-01-01

263

KY3F10 structural type and compounds similar to it in structure with chemical bonds of different nature  

International Nuclear Information System (INIS)

Consideration is given to a series of complexes structures of intermetallic compounds and relative carbides and nitrides, among which the cases of complete coincidence with the structure of typically ionic KY3F10 compound occur. Similarity of KYF10, Cr23C6, Tb5Rh6Sn18 structural types was established. It is shown that atomic motive, typical for KY3F10, is present in Ag36Te22Tl7 structure and is formed by Fe and Tl atoms. Atomic motive of Bi4Cu4Mn3 structure was interpreted as derivative of KY3F10 motive, and two submotives, close to the motive of KY3F10 structure, were distinguished in Cr21La6N23 structure

264

Spatiotemporal structure of biphoton entanglement in type-II parametric down-conversion  

International Nuclear Information System (INIS)

We investigate the spatiotemporal structure of the biphoton correlation in type-II parametric down-conversion (PDC). As in type-I PDC [Phys. Rev. Lett. 102, 223601 (2009)], we find that the correlation is nonfactorizable in space and time. Differently from type I, the type-II correlation in the spontaneous regime displays an asymmetric V-shaped structure in any cross section including time and one transverse dimension. This asymmetry along the temporal coordinate originates from the signal-idler group velocity mismatch and tends to disappear as the parametric gain is raised. We observe a progressive transition toward a symmetric X-shaped geometry similar to that found in type I when stimulated PDC becomes dominant. We also give quantitative evaluations of the localization in space and in time of the correlation, analyze its behavior for different crystal tuning angles, and underline qualitative differences with respect to type-I PDC.

265

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

266

Selection versus Structure: Explaining Family Type Differences in Contact with Close Kin  

Science.gov (United States)

This article focuses on one aspect of family networks, namely, the frequency of contact with close kin for adults living in different traditional and new family types. Two mechanisms are hypothesized to account for the differences. The first focuses on structural factors such as the number and type of persons in the primary family network,…

De Bruycker, Trees

2008-01-01

267

Novel crystallization conditions for tandem variant R67 DHFR yield a wild-type crystal structure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A modification of previously published protocols for the crystallization of homotetrameric R67 DHFR was used to crystallize a mixed wild-type and variant tandem dimer of R67 DHFR. Surprisingly, a fully wild-type crystal structure was obtained, apparently as a consequence of selective proteolytic degradation of the variant.

Yachnin, Brahm J.; Colin, Damien Y.; Volpato, Jordan P.; Ebert, Maximilian; Pelletier, Joelle N.; Berghuis, Albert M.

2011-01-01

268

Annular Protofibrils Are a Structurally and Functionally Distinct Type of Amyloid Oligomer*  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Amyloid oligomers are believed to play causal roles in several types of amyloid-related neurodegenerative diseases. Several different types of amyloid oligomers have been reported that differ in morphology, size, or toxicity, raising the question of the pathological significance and structural relationships between different amyloid oligomers. Annular protofibrils (APFs) have been described in oligomer preparations of many different amyloidogenic proteins and peptides ...

Kayed, Rakez; Pensalfini, Anna; Margol, Larry; Sokolov, Yuri; Sarsoza, Floyd; Head, Elizabeth; Hall, James; Glabe, Charles

2009-01-01

269

Structural Basis for Recognition of Urokinase-type Plasminogen Activator by Plasminogen Activator Inhibitor-1*  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 structura...

Lin, Zhonghui; Jiang, Longguang; Yuan, Cai; Jensen, Jan K.; Zhang, Xu; Luo, Zhipu; Furie, Barbara C.; Furie, Bruce; Andreasen, Peter A.; Huang, Mingdong

2011-01-01

270

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

271

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.Defence Science Journal, 2013, 63(4, pp.381-385, DOI:http://dx.doi.org/10.14429/dsj.63.2130

O. R. Nandagopan

2013-07-01

272

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

273

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

274

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)

275

Structures of Arg- and Gln-type bacterial cysteine dioxygenase homologs.  

Science.gov (United States)

In some bacteria, cysteine is converted to cysteine sulfinic acid by cysteine dioxygenases (CDO) that are only ?15-30% identical in sequence to mammalian CDOs. Among bacterial proteins having this range of sequence similarity to mammalian CDO are some that conserve an active site Arg residue ("Arg-type" enzymes) and some having a Gln substituted for this Arg ("Gln-type" enzymes). Here, we describe a structure from each of these enzyme types by analyzing structures originally solved by structural genomics groups but not published: a Bacillus subtilis "Arg-type" enzyme that has cysteine dioxygenase activity (BsCDO), and a Ralstonia eutropha "Gln-type" CDO homolog of uncharacterized activity (ReCDOhom). The BsCDO active site is well conserved with mammalian CDO, and a cysteine complex captured in the active site confirms that the cysteine binding mode is also similar. The ReCDOhom structure reveals a new active site Arg residue that is hydrogen bonding to an iron-bound diatomic molecule we have interpreted as dioxygen. Notably, the Arg position is not compatible with the mode of Cys binding seen in both rat CDO and BsCDO. As sequence alignments show that this newly discovered active site Arg is well conserved among "Gln-type" CDO enzymes, we conclude that the "Gln-type" CDO homologs are not authentic CDOs but will have substrate specificity more similar to 3-mercaptopropionate dioxygenases. PMID:25307852

Driggers, Camden M; Hartman, Steven J; Karplus, P Andrew

2015-01-01

276

Structure determination, electronic and optical properties of NaGe 2P 3O 12 and Cs 2GeP 4O 13  

Science.gov (United States)

Two alkali-metal germanium phosphates, namely, NaGe 2P 3O 12 and Cs 2GeP 4O 13, have been synthesized by the solid-state reactions and their structures determined by single-crystal X-ray diffraction. The structure of NaGe 2P 3O 12 features a Nasicon-type structure, crystallizing in space group R3¯ with a = 8.109(2), c = 21.536(8) (Å), V = 1226.3(6) Å 3, Z = 6, R1 = 0.0383 and ?R = 0.0960; Cs 2GeP 4O 13 crystallizes in triclinic space group P1¯ with a = 9.420(3), b = 10.209(4), c = 12.407(4) (Å), ? = 104.136(6), ? = 108.132(5), ? = 95.338(6)°, V = 1081.0(7) Å 3, Z = 2, R1 = 0.0445 and ?R = 0.1117. Additionally, the calculations of band structure and density of states were performed with the density functional theory method for the title compounds. The results show that the solid-state compounds of NaGe 2P 3O 12 and Cs 2GeP 4O 13 are insulator with indirect band-gap of 3.529 and 3.888 eV, respectively.

Zhao, Dan; Xie, Zhi; Hu, Jian-Ming; Zhang, Hao; Zhang, Wei-long; Yang, Song-Lin; Cheng, Wen-Dan

2009-03-01

277

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

278

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

279

Preparation, structure, and digestibility of crystalline A- and B-type aggregates from debranched waxy starches.  

Science.gov (United States)

Highly crystalline A- and B-type aggregates were prepared from short linear ?-1,4 glucans generated from completely debranched waxy maize and waxy potato starches by manipulating the chain length and crystallization conditions including starch solids concentration and crystallization temperature. The A-type crystalline products were more resistant to enzyme digestion than the B-type crystalline products, and the digestibility of the A- and B-type allomorphs was not correlated with the size of the aggregates formed. Annealing increased the peak melting temperature of the B-type crystallites, making it similar to that of the A-type crystallites, but did not improve the enzyme resistance of the B-type crystalline products. The possible reason for these results was due to the compact morphology as well as the denser packing pattern of double helices in A-type crystallites. Our observations counter the fact that most B-type native starches are more enzyme-resistant than A-type native starches. Crystalline type per se does not seem to be the key factor that controls the digestibility of native starch granules; the resistance of native starches with a B-type X-ray diffraction pattern is probably attributed to the other structural features in starch granules. PMID:24708989

Cai, Liming; Shi, Yong-Cheng

2014-05-25

280

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.

 
 
 
 
281

Life comparative analysis of energy consumption and CO? emissions of different building structural frame types.  

Science.gov (United States)

The objective of this research is to quantitatively measure and compare the environmental load and construction cost of different structural frame types. Construction cost also accounts for the costs of CO? emissions of input materials. The choice of structural frame type is a major consideration in construction, as this element represents about 33% of total building construction costs. In this research, four constructed buildings were analyzed, with these having either reinforced concrete (RC) or steel (S) structures. An input-output framework analysis was used to measure energy consumption and CO? emissions of input materials for each structural frame type. In addition, the CO? emissions cost was measured using the trading price of CO? emissions on the International Commodity Exchange. This research revealed that both energy consumption and CO? emissions were, on average, 26% lower with the RC structure than with the S structure, and the construction costs (including the CO? emissions cost) of the RC structure were about 9.8% lower, compared to the S structure. This research provides insights through which the construction industry will be able to respond to the carbon market, which is expected to continue to grow in the future. PMID:24227998

Kim, Sangyong; Moon, Joon-Ho; Shin, Yoonseok; Kim, Gwang-Hee; Seo, Deok-Seok

2013-01-01

282

Type AII lantibiotic bovicin HJ50 with a rare disulfide bond: structure, structure-activity relationships and mode of action.  

Science.gov (United States)

Lantibiotics are ribosomally synthesized antimicrobial peptides containing unusual amino acids. As promising alternatives to conventional antibiotics, they have a high potential for alleviating the problem of emergent antibiotic resistance, with possible applications in many industries that have antibacterial demand. Bovicin HJ50 is a type AII lantibiotic, the largest group of lantibiotics, comprising a linear N-terminal region and a globular C-terminal region. Interestingly, bovicin H50 has a disulfide bond that is rare in this group. Owing to limited information about the spatial structures of type AII lantibiotics, the functional regions of this type and the role of the disulfide bond are still unknown. In the present study, we resolved the solution structure of bovicin HJ50 using NMR spectroscopy. This is the first spatial structure of a type AII lantibiotic. Bovicin HJ50 exhibited high flexibility in aqueous solution, whereas varied rigidities were observed in the different rings with the conserved ring A being the most rigid. The charged residues Lys¹¹, Asp¹² and Lys³?, as well as the essential disulfide bond were critical for antimicrobial activity. Importantly, bovicin HJ50 showed not only peptidoglycan precursor lipid II-binding ability, but also pore-forming activity, which is significantly different from other bacteriostatic type AII lantibiotics, suggesting a novel antimicrobial mechanism. PMID:24814218

Zhang, Jie; Feng, Yingang; Teng, Kunling; Lin, Yuheng; Gao, Yong; Wang, Jinfeng; Zhong, Jin

2014-08-01

283

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

284

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

285

Modal flexibility-based damage detection of cantilever beam-type structures using baseline modification  

Science.gov (United States)

This paper presents a new damage detection approach for cantilever beam-type structures using the damage-induced inter-storey deflection (DIID) estimated by modal flexibility matrix. This approach can be utilized for damage detection of cantilever beam-type structures such as super high-rise buildings, high-rise apartment buildings, etc. Analytical studies on the DIID of cantilever beam-type structures have shown that the DIID abruptly occurs from damage location. Baseline modification concept was newly introduced to detect multiple damages in cantilever beam-type structures by changing the baseline to the prior damage location. This approach has a clear theoretical base and directly identifies damage location(s) without the use of a finite element (FE) model. For validating the applicability of the proposed approach to cantilever beam-type structures, a series of numerical and experimental studies on a 10-storey building model were carried out. From the tests, it was found that the damage locations can be successfully identified by the proposed approach for multiple damages as well as a single damage. In order to confirm the superiority of the proposed approach, a comparative study was carried out on two well-known damage metrics such as modal strain-based damage index approach and uniform load surface curvature approach.

Sung, S. H.; Koo, K. Y.; Jung, H. J.

2014-09-01

286

High temperature X-ray study of borates with different structure types  

International Nuclear Information System (INIS)

High-temperature X-ray diffraction in combination with thermal analysis and IR-spectroscopy are used to study Ga-, Mg-, Sr- and Sr-Ca-borates with different structure types. In the course of heating (air, heating rate 100 deg C/h) the range at heat stability and structure changes of hydrated borates and also phase composition of pyrolysis products are determined. Relation between thermal stability of studied borates and their crystal structure and the character of structural water is ascertained. Thermal decomposition processes are irreversible. Growth of heating temperature results in increase of boron atoms in tertiary coordination

287

Towards reduction of type II theories on SU(3) structure manifolds  

CERN Document Server

We revisit the reduction of type II supergravity on SU(3) structure manifolds, conjectured to lead to gauged N=2 supergravity in 4 dimensions. The reduction proceeds by expanding the invariant 2- and 3-forms of the SU(3) structure as well as the gauge potentials of the type II theory in the same set of forms, the analogues of harmonic forms in the case of Calabi-Yau reductions. By focussing on the metric sector, we arrive at a list of constraints these expansion forms should satisfy to yield a base point independent reduction. Identifying these constraints is a first step towards a first-principles reduction of type II on SU(3) structure manifolds.

Kashani-Poor, A K; Kashani-Poor, Amir-Kian; Minasian, Ruben

2007-01-01

288

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.

289

Spatially resolving the wind and disk structures around active B-type stars  

Science.gov (United States)

Long-baseline optical and IR interferometers now routinely resolve the wind and disk-like structures around early-type stars. The typical angular scales resolved by current generation of instruments are well bellow the milli-arcsecond level. These type of observations allow, in some cases for the first time, placing very tight constraints on current theories and models of the circumstellar structures around these type of stars. Specific examples of observations obtained at the Navy Prototype Optical interferometer of the spatially resolved regions around a luminous blue variable star P Cyg and a B-type star with circumstellar disk are presented. The need for connection between interferometric observables and physical parameters predicted by theory and numerical models are emphasized.

Tycner, Christopher

2011-07-01

290

Structural Characterization of Lignin in Wild-type versus COMT Down-regulated Switchgrass  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study examined the chemical structural characteristics of cellulolytic enzyme lignin isolated from switchgrass focusing on comparisons between wild-type control and caffeic acid 3-O-methyltransferase (COMT) down-regulated transgenic line. Nuclear magnetic resonance (NMR) techniques including 13C, 31P, and two-dimensional 13C-1H heteronuclear single quantum coherence (HSQC) as well as gel permeation chromatography (GPC) were employed. Compared to the wild-type, the COMT down-regulated tra...

ArthurRagauskas; YunqiaoPu; ChunxiangFu

2014-01-01

291

Song types and their structural features are associated with specific contexts in the banded wren  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We studied the use of song types and their acoustic features in different social contexts in the banded wren (Thryothorus pleurostictus), a resident tropical songbird in which males possess about 20 distinctive song types varying in duration, bandwidth, note composition, and trill structure. We recorded six focal males intensively for four days each while we observed context information such as during versus after dawn chorus, presence of the female, counter-versus solo-singing, location at t...

Trillo, P. A.; Vehrencamp, S. L.

2005-01-01

292

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2011-01-01

293

Multivalent ion conducting solids  

Energy Technology Data Exchange (ETDEWEB)

Solid electrolytes possess important characteristics for industrial applications. Only a single ionic species can macroscopically migrate in these solids. This paper described a the new NASICON (M-Zr-Nb-P-O) type system, exhibiting an exceptionally high level of trivalent M3+ ion conductivity on polycrystalline solids. The partial substitution of the smaller higher valent Nb5+ ion for Zr4+ stabilized the NASICON phase and realized the M3+ ion conduction in the NASICON structure. It was concluded that the conductivities of the series are comparable to those of the practically applied solid electrolytes of oxide anion conductors of YSZ and CSZ. 3 refs., 2 figs.

Imanaka, N. [Osaka Univ., Suita, Osaka (Japan). Dept. of Applied Chemistry

2008-07-01

294

High-pressure structural investigation of several zircon-type orthovanadates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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-fergu...

Errandonea, D.; Lacomba-perales, R.; Ruiz-fuertes, J.; Segura, A.; Achary, S. N.; Tyagi, A. K.

2009-01-01

295

Crystallization of Ta3Sn phase with the structure A15 type under high pressure  

International Nuclear Information System (INIS)

Superconducting properties of Ta3Sn samples with the type A15 structure synthesized of initial elements under high pressure are studied depending on the lattice parameters and degree of ordering of the alloy crystal lattice. The synthesis is conducted under constant pressure of 7.7 Pa in the temperature range 1070-1670 K. It is established that high pressure in the process of crystal growth with type A15 structure accelerates the crystallization of the ordered phase, having higher transition temperatures into superconducting state

296

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

International Nuclear Information System (INIS)

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

297

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)

298

Structural Analyses of Purified Human Immunodeficiency Virus Type 1 Intracellular Reverse Transcription Complexes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Retroviruses copy their RNA genome into a DNA molecule, but little is known of the structure of the complex mediating reverse transcription in vivo. We used confocal and electron microscopy to study the structure of human immunodeficiency virus type 1 (HIV-1) intracellular reverse transcription complexes (RTCs). Cytoplasmic extracts were prepared 3, 4, and 16 h after acute infection by Dounce homogenization in hypotonic buffer. RTCs were purified by velocity sedimentation, followed by density...

Nermut, Milan V.; Fassati, Ariberto

2003-01-01

299

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

300

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

 
 
 
 
301

Allomorph distribution and granule structure of lotus rhizome C-type starch during gelatinization.  

Science.gov (United States)

The allomorph distribution and granule structure of C-type starch from lotus rhizomes were investigated using a combination of techniques during gelatinization. The disruption of crystallinity during gelatinization began from the end distant from the eccentric hilum and then propagated into the center of granule. The periphery of hilum end was finally gelatinized, accompanied by high swelling. The crystallinity changed from C-type to A-type via CA-type during gelatinization, and finally became amorphous structure. The amylose content, crystal degree, helix content, ratio of 1045/1022cm(-1), and peak intensity of crystalline lamellae of gelatinizing starch significantly decreased after 70°C. The amorphous content and ratio of 1022/995cm(-1) increased after 70°C. This study elucidated that B-type allomorph was mainly arranged in the distal region of eccentric hilum, A-type allomorph was mainly located in the periphery of hilum end, and the center of granule was a mixed distribution of A- and B-type allomorphs. PMID:24001859

Cai, Canhui; Cai, Jinwen; Man, Jianmin; Yang, Yang; Wang, Zhifeng; Wei, Cunxu

2014-01-01

302

Structural integrity of heat exchanger components for top-entry loop type FBR  

International Nuclear Information System (INIS)

This paper presents structural integrity of an intermediate heat exchanger and a steam generator, especially identifies the structural design and evaluation results, for a demonstration reactor, Top-entry Loop Type FBR performed in Japan. Seismic analyses were performed for these components subjected to horizontal and vertical loadings. Stress analyses were performed for locations on thermal severe loadings of these components. A Japanese structural design guide for a demonstration FBR is used as design criteria. As a result, buckling stiffness of vessel walls were sufficiently reasonable to satisfy the design guide. Thermal ratchetting strain limits and creep fatigue limits of the design guide were satisfied. (author)

303

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

Panchal, V.; Errandonea, D.; Segura, A.; Rodriguez-hernandez, P.; Munoz, A.; Lopez-moreno, S.; Bettinelli, M.

2012-01-01

304

NdTaO4 - a new structural type in TRTaO4 series  

International Nuclear Information System (INIS)

Crystals of new NdTaO4 modification, with the crystallographic parameters being a=5.422(2), c=5.242(2) A, ?=96.76(4) deg, sp.gr. Pa, Z=2 are synthesized. The structure is refined using LSF method in the anisotropic approximation up to R=0.057. (110) faces of Nd-eight-vertex species, connected by columns of Ta-octahedrons, are determined in the structure. Two earlier known modifications of NdTaO4 with fergusonite and ?-fergusonite structural types are considered to be of a higher temperature in relation to the investigated crystals

305

Structure and magnetic properties of SmCo7-xTix with TbCu7-type structure  

Science.gov (United States)

The SmCo7-xTix, x=0-0.56 bulk samples are prepared by arc melting. X-ray diffraction indicates that samples with 0.2TbCu7-type structure phase and other minor phases appear for other values of x, which indicates that Ti helps stabilize the 1-7 phase. The lattice parameters ratio (c/a) increases with increasing Ti concentration. Room temperature saturation magnetization and Curie temperature decrease with increasing x. X-ray diffraction and magnetization measurements on aligned samples show that all samples studied have uniaxial anisotropy. The anisotropy field is found to increase with increasing x reaching a maximum of 175 kOe at x=0.28 and then decreases for higher values of x. This anisotropy field is 20% higher than that of the same compound with Th2Zn17-type structure.

Zhou, J.; Al-Omari, I. A.; Liu, J. P.; Sellmyer, D. J.

2000-05-01

306

The Robinson-Trautman Type III Prolongation Structure Contains K$_2$  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The minimal prolongation structure for the Robinson-Trautman equations of Petrov type III is shown to always include the infinite-dimensional, contragredient algebra, K$_2$, which is of infinite growth. Knowledge of faithful representations of this algebra would allow the determination of B\\"acklund transformations to evolve new solutions.

Finley, Iii

1995-01-01

307

Pre-adsorbed type-I collagen structure-dependent changes in osteoblastic phenotype  

International Nuclear Information System (INIS)

Type-I collagen is the most abundant extracellular matrix in bones and modulates various functions of osteoblasts. We prepared two different structures of type-I collagen on tissue culture grade polystylene (TCPS) surfaces, one is feltwork structure of filamentous molecules from acid solutions (ACs) and the other is network structure of fibrils from neutral solutions (NCs), to examine effects of the structures on the maturation process of osteoblast-like cells. No significant differences of cell proliferation were observed between TCPS and ACs, but NCs delayed the proliferation. In initial cell attachment, the cells on ACs had tense lamellipodia with sharp tips, while those on NCs had loose lamellipodia. No detectable differences in levels of expressed integrin ?2- and ?5-subunits were observed between the structures. Although the matrix mineralization in NCs was also delayed in comparison with TCPS and ACs, fully mineralized levels in NCs were the same as those of TCPS and ACs. In addition, although we examined the effects of densities of pre-adsorbed collagen molecules on osteoblast maturation, the effects were less serious than those of the structures. This study suggests that the structures of collagen affect proliferation and mineralization of osteoblast-like cells

308

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.)

309

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

2014-11-21

310

Crystal structure of alluaudite-type Na4Co(MoO43  

Directory of Open Access Journals (Sweden)

Full Text Available The title compound, tetrasodium cobalt(II tris[molybdate(IV], was prepared by solid-state reactions. The structure is isotypic with Na3In2(AsO43 and Na3In2(PO43. The main structural feature is the presence of infinite chains of edge-sharing X2O10 (X = Co/Na dimers, which are linked by MoO4 tetrahedra, forming a three-dimensional framework enclosing two types of hexagonal 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.

Rawia Nasri

2014-09-01

311

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

International Nuclear Information System (INIS)

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

312

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

International Nuclear Information System (INIS)

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

313

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

314

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

International Nuclear Information System (INIS)

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

315

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

316

Pt29Zn49, a complex defective AlB2-type derivative structure  

International Nuclear Information System (INIS)

The crystal structure of the title compound has been determined by X-ray diffraction means. Pt29Zn49 forms a complex superstructure of a defective AlB2-type derivative of the order 58: a = 279.0(1) pm, b = 11895.2(4) pm, c = 698.0(1) pm, space group Amm2, Z = 2. Ordering of vacancies is accompanied by a particular distortion of defective graphite-like 63 nets consisting exclusively of Zn atoms. The ordering induces a modulation of the structure along a h of an AlB2-type structure with a periodicity of nearly 12 nm. A mechanistic model is proposed elucidating how Pt29Zn49 evolves from the eutectoid decomposition of the inter-mediate high temperature precursor Pt7Zn12

317

Three Types of Flows in the Structure of the Solar Wind  

Science.gov (United States)

An experimental study of the source and formation of large-scale streams in the solar wind is presented. Radio-astronomical data from 1998 are compared with optical SOHO observations and solar coronal magnetic fields calculated from Zeeman data obtained at the Wilcox Observatory. A correlation between the geometry of the solar-wind transition region and the strength of coronal magnetic fields is revealed. For the moderate heliolatitudes studied, this correlation divides into three branches corresponding to three types of coronal magnetic-field structures: open structures with field lines escaping into interplanetary space, closed structures with loop-like field lines, and intermediate structures including both open and closed configurations. High-speed streams of solar wind originate in regions with open magnetic structures. These structures are connected with the lateral lobes of streamers at moderate heliolatitudes. Low-speed flows originate above closed magnetic structures, typical of the main bodies of streamers. The lowest-speed solar-wind flows are not associated with coronal streamer structures, and originate in coronal regions with intermediate magnetic configurations simultaneously containing open and closed field lines. In these regions, the white-light corona becomes an extended and amorphous area with high luminosity, which stratifies into a radial structure with narrow stripes at higher resolution.

Lotova, N. A.; Obridko, V. N.; Vladimirskii, K. V.

2002-04-01

318

Crystal structure of Sc5Ga4 and new compounds of Ho11Ge10 structural type  

International Nuclear Information System (INIS)

X-ray diffraction analysis (of monocrystal and powder) is used to determine crystal structure of earlier known Sc5Ga4 and Hf5Ga4 compounds and ternary X'-phases forming inSc-Ti(Zr,Nb)-Ga and Zr-Ti(V)-Ga systems. Sc5Ga4 compound belongs to Ho11Ge10 structural type (a=1.0366, c=1.5305 nm) with deficit of gallium atoms (the correct point system 16(m) is occupied only by 12 gallium atoms). Composition of Hf5Ga4 compound is actually described by Hf11Ga10 formula and Ho11Ge10 structure. For X'-phases homogeneity regions are defined more exactly, and it is shown that their structure belongs to Ho11Ge10 type. In Sc-Ti(Zr,Nb)-Ga systems both ternary X'-phases and solid solutions on the basis of Sc5Ga4 compound are formed and in Sc-Hf-Ga system two solid solutions on Sc5Ga4 and Hf11Ga10 basis are in equilibrium

319

An Investigation on the Morphological Structure of IC59: A New Type of Morphology of BRCs?  

CERN Document Server

With references to recent observational results on the nebula IC59, we applied our previously developed Smoothed Particle Hydrodynamics (SPH) code which is based on Radiative Driven Implosion (RDI) model, to investigate the possible formation mechanism for the observed morphological structures of differently shaped BRCs. The simulation results confirmed the existence of the 4th type morphology of BRCs -- type M BRC. We are able to find the necessary condition for the appearance of the type M BRC based on the fact that the simulated physical properties of the cloud are consistent with observations on IC59. More importantly, the prospect of RDI triggered star formation by RDI model in all of the observed type M BRCs is ruthlessly eliminated.

Miao, Jingqi; White, Glenn J; Nelson, Richard P

2010-01-01

320

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

International Nuclear Information System (INIS)

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

 
 
 
 
321

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

Science.gov (United States)

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

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

2014-09-14

322

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

323

First structural evidence of sequestration of mRNA cap structures by type 1 ribosome inactivating protein from Momordica balsamina.  

Science.gov (United States)

This is the first structural evidence of recognition of mRNA cap structures by a ribosome inactivating protein. It is well known that a unique cap structure is formed at the 5' end of mRNA for carrying out various processes including mRNA maturation, translation initiation, and RNA turnover. The binding studies and crystal structure determinations of type 1 ribosome inactivating protein (RIP-1) from Momordica balsamina (MbRIP-1) were carried out with mRNA cap structures including (i) N7-methyl guanine (m7G), (ii) N7-methyl guanosine diphosphate (m7GDP), and (iii) N7-methyl guanosine triphosphate (m7GTP). These compounds showed affinities to MbRIP-1 at nanomolar concentrations. The structure determinations of the complexes of MbRIP-1 with m7G, m7GDP, and m7GTP at 2.65, 1.77, and 1.75 Å resolutions revealed that all the three compounds bound to MbRIP-1 in the substrate binding site at the positions which are slightly shifted towards Glu85 as compared to those of rRNA substrates. In this position, Glu85 forms several hydrogen bonds with guanine moiety while N-7 methyl group forms van der Waals contacts. However, the guanine rings are poorly stacked in these complexes. Thus, the mode of binding by MbRIP-1 to mRNA cap structures is different which results in the inhibition of depurination. Since some viruses are known to exploit the capping property of the host, this action of MbRIP-1 may have implications for the antiviral activity of this protein in vivo. The understanding of the mode of binding of MbRIP-1 to cap structures may also assist in the design of anti-viral agents. PMID:23280611

Kushwaha, Gajraj Singh; Yamini, Shavait; Kumar, Mukesh; Sinha, Mau; Kaur, Punit; Sharma, Sujata; Singh, Tej P

2013-05-01

324

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

International Nuclear Information System (INIS)

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

325

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

326

Crystalline and structural properties of acid-modified lotus rhizome C-type starch.  

Science.gov (United States)

The crystalline and structural properties of acid-modified C-type starch from lotus rhizomes were investigated using a combination of techniques. The degradation of granule during hydrolysis began from the end distant from the hilum and then propagated into the center of granule, accompanied by loss of birefringence. The crystallinity changed from C-type to A-type via CA-type during hydrolysis. At the early stage of hydrolysis, the amylose content substantially reduced, the peak and conclusion gelatinization temperatures increased, and the enthalpy decreased. During hydrolysis, the double helix content gradually increased and the amorphous component decreased, the lamellar peak intensity firstly increased and then decreased accompanied by hydrolysis of amorphous and crystalline regions. This study elucidated that B-type allomorph was mainly arranged in the distal region of eccentric hilum, A-type allomorph was mainly located in the periphery of hilum end, and the center of granule was a mixed distribution of A- and B-type allomorphs. PMID:24507349

Cai, Jinwen; Cai, Canhui; Man, Jianmin; Yang, Yang; Zhang, Fengmin; Wei, Cunxu

2014-02-15

327

Structure-activity relationships of lanostane-type triterpenoids from Ganoderma lingzhi as ?-glucosidase inhibitors.  

Science.gov (United States)

A series of lanostane-type triterpenoids, identified as ganoderma alcohols and ganoderma acids, were isolated from the fruiting body of Ganoderma lingzhi. Some of these compounds were confirmed as active inhibitors of the in vitro human recombinant aldose reductase. This paper aims to explain the structural requirement for ?-glucosidase inhibition. Our structure-activity studies of ganoderma alcohols showed that the OH substituent at C-3 and the double-bond moiety at C-24 and C-25 are necessary to increase ?-glucosidase inhibitory activity. The structure-activity relationships of ganoderma acids revealed that the OH substituent at C-11 is an important feature and that the carboxylic group in the side chain is essential for the recognition of ?-glucosidase inhibitory activity. Moreover, the double-bond moiety at C-20 and C-22 in the side chain and the OH substituent at C-3 of ganoderma acids improve ?-glucosidase inhibitory activity. These results provide an approach with which to consider the structural requirements of lanostane-type triterpenoids from G. lingzhi. An understanding of these requirements is considered necessary in order to improve a new type of ?-glucosidase inhibitor. PMID:24070782

Fatmawati, Sri; Kondo, Ryuichiro; Shimizu, Kuniyoshi

2013-11-01

328

A study of the development of a new type of bulb bracket for offshore structures using suitable casting steel  

Science.gov (United States)

In this study, the optimum structural design of brackets for offshore structures was carried out through the ANSYS program. We wished to propose a new type of bulb bracket made by a casting process compared with the built-up type of bracket. For a better structural design of the bracket, we can't adopt face plate but stiffener and circular type shape at the diagonal surface line. Under the new type of bulb bracket made by a casting process, it was possible to reduce the size by about 30% and the weight by about 50% compared with the face-plate type of bracket.

Kim, Tae-Won; Kang, Chung-Gil; Park, Sang-Sik

2010-06-01

329

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.

330

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

331

A new tetragonal structure type for Li2B2C.  

Science.gov (United States)

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

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

2015-01-01

332

Complex antimonides with Th3P4 structure type and thermoelectric properties  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This thesis concerns the study of complex antimonides with Th3P4 structure type and their potential as p-type materials for thermoelectric power generation. Such materials are characterized by the figure of merit ZT = ?2T/??, where ? is the Seebeck coefficient, ? the electrical resistivity and ? the thermal conductivity. R4Sb3 binary compounds (R = La, Ce, Sm and Yb) and ternary Yb4-xR'xSb3 (R = La, Sm, Ce and Eu) and Yb4Sb3-yXy (X = Se, Te, As, Bi and I) have been synthesized by high t...

Chamoire, Audrey

2009-01-01

333

Comparative Evolutionary Analysis of the Major Structural Subunit of Vibrio vulnificus Type IV Pili  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type IV pili contribute to virulence in Vibrio vulnificus, the bacterium responsible for the majority of fatal seafood-related infections. Here, we performed within- and between-species evolutionary analysis of the gene that encodes the major structural subunit of the pilus, pilA, by comparing it with pilD and gyrB, the genes encoding the type IV prepilin peptidase and ? subunit of DNA gyrase, respectively. Although the diversity in pilD and gyrB is similar to each other and likely to have a...

Chattopadhyay, Sujay; Paranjpye, Rohinee N.; Dykhuizen, Daniel E.; Sokurenko, Evgeni V.; Strom, Mark S.

2009-01-01

334

Effect of mineral acid type on polymerization of molybdate ion in anionite structure  

International Nuclear Information System (INIS)

Some problems of molybdate ion ionic changes in a polymeric matrix of AV-17-10P anionite with a macropore structure after its saturation with molybdenum from sodium molybdate solution (pH=9) are considered. It is established that molybdenum washing-out degree in strong-acid media is dependent on the type of mineral acid that is conditioned by the change of molybdate ion ionic state in solutions. It is shown that with the increase of molybdenum content in anionite qranules, polymerization of molybdate ion up to tetra-molybdate ion of the Mo8O264- type takes course in a matrix

335

Influence of chemical composition on the structure of cast K13 type steel  

International Nuclear Information System (INIS)

Influence of chemical composition on the structure of cast K13 type chromium steel containing 12-13%Cr is studied. The possibility is shown to change essentially the character of microstructure- ferrite/austenito ratio, their mutual disposition and a rate of solid solution alloyage and a value of chemical microheterogeneity varying within small limits C, Mn, Si, and some other elements contents. It allows one to affect the whole complex of mechanical, technological, and operation characteristics of K13 type chromium stainless steel

336

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

337

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

338

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

Science.gov (United States)

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-? 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. PMID:21199867

Lin, Zhonghui; Jiang, Longguang; Yuan, Cai; Jensen, Jan K; Zhang, Xu; Luo, Zhipu; Furie, Barbara C; Furie, Bruce; Andreasen, Peter A; Huang, Mingdong

2011-03-01

339

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

340

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Kahn, Richard; Curiel, David T.; Glasgow, Joel N.; Raaij, Mark J.

2010-01-01

 
 
 
 
341

Electronic structure in type CsCl alloys: quasizone cluster calculations  

International Nuclear Information System (INIS)

The possibilities were investigated to use the scattering Xsub(?) method with k-dependent boundary conditions in calculations of electronic structure for ordered alloys of transition metals. State density calculations were made for CuZn, TiFe and CuBe systems with CsCl type structure. Level widths and the position of main peaks of enerqy-level density agree well with band calculations and experimental data on X-ray photoelectron spectra. This fact confirms satisfactory correctness of the calculation method sugqested

342

Fano-type spectral asymmetry and its control for plasmonic metal-insulator-metal stub structures.  

Science.gov (United States)

We use coupled mode theory (CMT) to analyze a metal-insulator-metal (MIM) plasmonic stub structure, to reveal the existence of asymmetry in its transmittance spectra. Including the effect of the near field contribution for the stub structure, the observed asymmetry is interpreted as Fano-type interference between the quasi-continuum T-junction-resonator local-modes and discrete stub eigenmodes. Based on the asymmetry factor derived from the CMT analysis, methods to control transmittance asymmetry are also demonstrated. PMID:21643350

Piao, Xianji; Yu, Sunkyu; Koo, Sukmo; Lee, Kwanghee; Park, Namkyoo

2011-05-23

343

Exploration of heterogeneous duplex grain structure in type 304 austenitic stainless steel using ultrasonic spectroscopy  

International Nuclear Information System (INIS)

Previous cyclic stress-strain tests at different temperatures for a give constant strain range on a single reference heat (9T2796) of Type 304 austenitic stainless steel showed many unexpected features, the metallographic investigations of the fatigued specimens showing the existence of heterogeneous duplex grain structure of ASTM grain size numbers ranging from 1.6 to 3.2. The necessity of using a non-destructive technique to sort out the machined and heat treated specimens according to their grain structures prior to testing is discussed. The qualitative results presented indicate the potential of using ultrasonic spectroscopy for this purpose. (UK)

344

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

345

Structure and Properties of {\\alpha}-NaFeO2-type Ternary Sodium Iridates  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The synthesis, structure, and elementary magnetic and electronic properties are reported for layered compounds of the type Na3-xMIr2O6 and Na3-xM2IrO6, where M is a transition metal from the 3d series (M=Zn, Cu, Ni, Co, Fe and Mn). The rhombohedral structures, in space group R-3m, were determined by refinement of neutron and synchrotron powder diffraction data. No clear evidence for long range 2:1 or 1:2 honeycomb-like M/Ir ordering was found in the neutron powder diffractio...

Baroudi, Kristen; Yim, Cindi; Wu, Hui; Huang, Qingzhen; Roudebush, John H.; Vavilova, Eugenia; Grafe, Hans-joachim; Kataev, Vladislav; Buechner, Bernd; Ji, Huiwen; Kuo, Changyang; Hu, Zhiwei; Pi, Tun-wen; Pao, Chiwen; Lee, Jyhfu

2013-01-01

346

Structure prediction of P1-type ATPases and molecular dynamics simulations on their Metal Binding Domains  

Digital Repository Infrastructure Vision for European Research (DRIVER)

P1-type ATPases are a special kind of ATP driven pumps which transport soft heavy metals (Cu+, Zn2+, Pb2+ Cd2+) across the cell membranes. Their complete structure is, in general, unknown. We are interested in the structure and dynamics of the transmembrane part of the Cadmium ATPase (CadA) and the metal binding domains of the human Copper transporting Menkes ATPase. Sequence similarity and hydropathy analyses, completed by experiments have shown that soft metal pumps are constituted of 8 tra...

Arumugam, Karthik

2009-01-01

347

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 andR 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

348

Analysis and interpretation of the quasiperiodical structure of a type IV burst  

International Nuclear Information System (INIS)

An analysis is described of the type IV radio burst (with a quasiperiodical structure) observed in the 270 to 470 MHz frequency range with the radio spectrograph of the Ondrejov Observatory on July 3, 1974. The burst probably originated in the complicated magnetic structure of active region McMath 13043 following a proton flare. The method of spectral analysis and signal filtering was used to process the event. The results were discussed from the point of view of statistical likelihood. The observed periods of intensity modulation of the burst are interpreted in the model considered as the periods of generation and acceleration of electron beams in an X-type magnetic configuration, as periods in electron beam injections into the coronal plasma taking into account the finite velocities of propagation of electromagnetic radiations. (author)

349

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

350

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Engsig-karup, Allan Peter; Hesthaven, Jan; Bingham, Harry B.; Warburton, Tim

2008-01-01

351

Multilocus Sequence Typing Analysis of Staphylococcus lugdunensis Implies a Clonal Population Structure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Staphylococcus lugdunensis is recognized as one of the major pathogenic species within the genus Staphylococcus, even though it belongs to the coagulase-negative group. A multilocus sequence typing (MLST) scheme was developed to study the genetic relationships and population structure of 87 S. lugdunensis isolates from various clinical and geographic sources by DNA sequence analysis of seven housekeeping genes (aroE, dat, ddl, gmk, ldh, recA, and yqiL). The number of alleles ranged from four ...

Chassain, Benoi?t; Leme?e, Ludovic; Didi, Jennifer; Thiberge, Jean-michel; Brisse, Sylvain; Pons, Jean-louis; Pestel-caron, Martine

2012-01-01

352

Structure-activity relationships of polybiguanides with activity against human immunodeficiency virus type 1  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Previous investigations showing that polydisperse biguanide (PDBG) molecules have activity against human immunodeficiency virus type 1 (HIV-1) also suggested a relationship between PDBG biologic activity and the lengths of hydrocarbon linkers surrounding the positively charged biguanide unit. To better define structure-activity relationships, PDBG molecules with select linker lengths were evaluated for cytotoxicity, anti-HIV-1 activity, and in vivo toxicity. Results of the in vitro experiment...

Passic, Shendra R.; Ferguson, Mary Lee; Catalone, Bradley J.; Kish-catalone, Tina; Kholodovych, Vladyslav; Zhu, Wei; Welsh, William; Rando, Robert; Howett, Mary K.; Wigdahl, Brian; Labib, Mohamed; Krebs, Fred C.

2010-01-01

353

Inferring dark halo structure from observed scaling laws of late type galaxies and LSB's  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We re-examine the Fall & Efstathiou (1980) scenario for galaxy formation, including the dark halo gravitational reaction to the formation of the baryon disk, as well as continuous variations in the intrinsic halo density profile. The recently published rotation curves of LSB and dwarf galaxies together with previously known scaling relations provide sufficient information on the present day structure of late type disk galaxies to invert the problem. By requiring that the mod...

Hernandez, X.; Gilmore, Gerard

1997-01-01

354

Sandwich Structure Type RF-MEMS Variable Capacitor with Low Voltage Controllability and Wide Tuning Range  

Science.gov (United States)

A sandwich structure type RF-MEMS variable capacitor is proposed, that consists of a movable middle plate, and fixed top and bottom plates having different areas. Simulation results show that the proposed capacitor can operate at a control voltage of less than 3.2V; it achieves a tuning range of 4.8:1 (capacitance: 630-130fF) in the range of 0 to 3.2V and at a frequency of 7.5GHz.

Nishimoto, Takuma; Yamashita, Kiichi; Ohhata, Kenichi

355

Quaternary Structure and Functional Unit of Energy Coupling Factor (ECF)-type Transporters*  

Digital Repository Infrastructure Vision for European Research (DRIVER)

ATP-binding cassette (ABC) transporters mediate transport of diverse substrates across membranes. We have determined the quaternary structure and functional unit of the recently discovered ECF-type (energy coupling factor) of ABC transporters, which is widespread among prokaryotes. ECF transporters are protein complexes consisting of a conserved energizing module (two peripheral ATPases and the integral membrane protein EcfT) and a non-conserved integral membrane protein responsible for subst...

Ter Beek, Josy; Duurkens, Ria H.; Erkens, Guus B.; Slotboom, Dirk Jan

2011-01-01

356

New phosphides of the Nb4CoSi type structure  

International Nuclear Information System (INIS)

For the first time stated is the formation of Hf4FeP, Hf4CoP and TaFeP phosphides having the Nb4CoSi type structure. Binary intermetallic compounds TaCo, Ta2Ni, Zr2Co, Zr2Ni, Hf2Ni are shown to disslove up to 17 at.% P. Maximum composition of these solid solutions is characterized by ordered distribution of Co(or Ni)and P atoms

357

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

358

Design, synthesis, antiviral activity, and structure-activity relationships (SARs) of two types of structurally novel phenanthroindo/quinolizidine analogues.  

Science.gov (United States)

To investigate the influence of the variation of the original skeletons of natural phenanthroindo/quinolizidine alkaloids on antiviral activities, two types of structurally totally novel analogues 7a, 7b, 16a, and 16b were designed, synthesized, and evaluated against tobacco mosaic virus (TMV) for the first time. Bioassay results indicated that all four of the newly designed analogues showed good to excellent antiviral activities, among which analogue 16a dispalyed comparable activity with that of ningnanmycin, perhaps one of the most successful commercial antiviral agents, thus emerging as a potential inhibitor of plant virus and serving as a new lead for further optimization. Further structure-activity relationships are also discussed, demonstrating for the first time that the same changes of the original skeletons of phenanthroindolizidine and phenanthroquinolizidine exihibted totally different antiviral activities results, providing some original and useful information about the preferential conformation for maintaining high activities. PMID:24467600

Su, Bo; Chen, Fazhong; Wang, Lizhong; Wang, Qingmin

2014-02-12

359

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

360

?erenkov-type second-harmonic spectroscopy in random nonlinear photonic structures.  

Science.gov (United States)

We report on experimental and theoretical studies of ?erenkov-type second-harmonic generation in random nonlinear photonic structures with different two-dimensional distributions of the ferroelectric domains. We utilize ?erenkov-type second-harmonic generation spectroscopy to estimate the average ferroelectric domain size by analyzing the spatial Fourier spectrum of the domain patterns. This is measured by scanning the ?erenkov second-harmonic signal for different angles of incidence and light polarizations of the fundamental wave. By comparing the experimental results with numerically simulated Fourier spectra, the corresponding domain patterns are retrieved, which are in a good correspondence with images obtained by ?erenkov-type second-harmonic generation microscopy. PMID:23571912

Ayoub, Mousa; Roedig, Philip; Koynov, Kaloian; Imbrock, Jörg; Denz, Cornelia

2013-04-01

 
 
 
 
361

Magnetic, structural and thermal properties of the Finemet-type powders prepared by mechanical alloying  

Science.gov (United States)

The mechanical alloying process has been used to prepare nanocrystalline Fe73.5Si13.5B9Nb3Cu1 powders in a high energy planetary ball-mill Retsch PM400/2. Morphological, microstructural, structural, thermal and magnetic characterizations of the powders milled several times were investigated by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry and hysteresis meter. A mixture of Fe(Si)-type nanograins (14 nm), Fe2B boride phase (˜12 nm), and bcc substitutional Fe(B)-type solid solution is obtained after 150 h of milling. The coercivity and saturation magnetization values are about 62 Oe and 14 emu/g, respectively. Several magnetic transition temperatures are revealed in the DSC scans of the ball-milled powders in the temperature ranges 500-560 °C and 599-606 °C, related to the Fe(B) and Fe(Si)-type phases, respectively.

Alleg, S.; Kartout, S.; Ibrir, M.; Azzaza, S.; Fenineche, N. E.; Suñol, J. J.

2013-04-01

362

Two new silicate structures based on a rhodesite-type heteropolyhedral microporous framework.  

Science.gov (United States)

Two new members of the mero-plesiotype rhodesite series [Sr(2)Na(2)(Si(8)O(19)).4H(2)O, abbreviated as TR09; SrNa(4)(Si(8)O(19)).4H(2)O, TR10] have been hydrothermally synthesized in Teflon-lined autoclaves at 503 K and structurally characterized using X-ray diffraction single-crystal data. The crystal structures were solved by direct methods and refined to R = 0.021 [TR09; 3317 reflections with I(o) > 2sigma(I(o))] and R = 0.033 [TR10; 5007 reflections with I(o) > 2sigma(I(o))]. Both structures are based on a rhodesite-type microporous heteropolyhedral framework, where two types of channels are within the double silicate layer that alternates with an ;octahedral' O sheet. The large Sr(2+) cation constrains to the roughly ellipsoidal shape of the channels. The H(2)O molecules are located both in the O sheets and in the channels, where they are loosely hydrogen bonded. The crystal-chemical features that allow flexibility to the rhodesite-type microporous heteropolyhedral framework and make it interesting for possible technological applications are discussed. PMID:20305348

Cadoni, Marcella; Ferraris, Giovanni

2010-04-01

363

Synthesis and Crystal Structures of Zirconium Phosphate Fluorides with New 2D and 3D Structure Types  

Science.gov (United States)

Three new zirconium phosphate fluorides, [amH2]0.5 [Zr2(PO4)(HPO4)2F2]·0.5H2O (1), [amH2]1.5[Zr3(PO4)3F6]·1.5H2O (2) (am=trans-1,4-diaminocyclohexane for 1 and 2), and [amH2]0.5[Zr3(PO4)3(HPO4)F2]·1.5H2O (am=2,2-dimethyl-1,3-diaminopropane) (3), were synthesized under hydrothermal conditions and structurally characterized. Zr is octahedrally coordinated in all three structures. In 1, the octahedra consist of ZrO6 and ZrO4F2 units. Compound 2 is made exclusively of ZrO4F2. In 3, there are three different types of Zr-octahedra, namely, ZrO6, ZrO5F, and ZrO4F2. The Zr octahedra and PO4 tetrahedra are connected via non-OH oxygen atoms. In 1 and 2, all F atoms are terminal, whereas in 3, one of the two F atoms bridges between the ZrO5F and ZrO4F2 octahedra. In structures 1 and 2 with higher F/Zr ratios, two-dimensional inorganic networks exist. The inorganic sheets are connected by the protonated templates via N-H···F and in 1 additionally by O-H···F hydrogen bonds. In 3, the lower F/Zr ratio results in the formation of a three-dimensional inorganic framework with characteristic 'double' channels in which the highly disordered templates are located. The existence of several structure types in the ZrPOF-n family is discussed on the basis of different template geometry and F/Zr ratios.

Wloka, Martin; Troyanov, Sergei I.; Kemnitz, Erhard

2000-01-01

364

Structure and assembly of an inner membrane platform for initiation of type IV pilus biogenesis  

Science.gov (United States)

Type IV pili are long fibers that are assembled by polymerization of a major pilin protein in the periplasm of a wide range of bacteria and archaea. They play crucial roles in pathogenesis, DNA transformation, and motility, and are capable of rapid retraction, generating powerful motor forces. PilN and PilO are integral inner membrane proteins that are essential for type IV pilus formation. Here, we show that PilN and PilO from Thermus thermophilus can be isolated as a complex with PilM, a cytoplasmic protein with structural similarities to the cytoskeletal protein MreB. The crystal structure of the periplasmic portion of PilN forms a homodimer with an extensive, conserved interaction interface. We conducted serial 3D reconstructions by electron microscopy of PilMN, PilMNO, and PilMNO bound to the major pilin protein PilA4, to chart the assembly of the inner membrane pilus biogenesis platform. PilN drives the dimerization of the PilMN complex with a stoichiometry of 2:2; binding of two PilO monomers then causes the PilN periplasmic domains to dissociate. Finally, two PilA4 monomers bind to the periplasmic domains of PilN and PilO, to generate a T-shaped complex that is primed for addition of the pilin to the nascent pilus fiber. Docking of structures for PilM, PilN, PilO, and PilA4 into the electron density maps of the transmembrane complexes was used to generate a sequence of molecular structures that chart the initial events in type IV pilus formation, and provide structural information on the early events in this important secretion process. PMID:24218553

Karuppiah, Vijaykumar; Collins, Richard F.; Thistlethwaite, Angela; Gao, Ya; Derrick, Jeremy P.

2013-01-01

365

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

366

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-05-20

367

A density functional study of the chemical differences between Type I and Type II MoS2-based structures in hydrotreating catalysts.  

Science.gov (United States)

Density functional theory is used to investigate the origin of the activity differences between Type I and Type II MoS2-based structures in hydrotreating catalysts. It is well known that the Type II structures, where only weak interactions with the support exist, have a higher catalytic activity than Type I structures, where Mo-O linkages to the alumina are present. The present results show that the differences in activities for MoS2 and Co-Mo-S structures can be attributed to the electronic and bonding differences introduced by the bridging O bonds. We find that the Mo-O linkages are most probably located on the (1010) S edge. The presence of oxygen linkages increases the energy required to form sulfur vacancies significantly so that almost no vacancies can be formed at these and neighboring sites. In this way, the reactivity of the S edge is reduced. In addition, the studies also show that the linkages introduce changes in the one-dimensional metallic-like brim states. Furthermore, the presence of oxygen linkages also changes the energetics of hydrogen adsorption, which becomes less exothermic on sulfur sites directly above linkages and more exothermic on sulfur sites adjacent to linkages. The present results explain previously observed differences in Type I-Type II transition temperatures for Co-Mo-S structures with different Co contents. PMID:16851217

Hinnemann, Berit; Nørskov, Jens K; Topsøe, Henrik

2005-02-17

368

Fracture limit prediction for a double safety structure in cylindrical-type lithium secondary batteries  

International Nuclear Information System (INIS)

In this study, a double safety structure used for cylindrical-type lithium secondary batteries is newly introduced. The structure is necessary to prevent users and the cylindrical-type secondary batteries from unpredictable explosions due to a temporary increase in the inner pressure of the batteries. The double safety structure consists of a primary safety component as micro half-blanked component, and a secondary safety device as V-notched part. For the double safety device, both the mentioned components are considered by the micro half-blanking and the V-notch forming processes with numerical and experimental predictions for the fracture limit. The mechanical properties are investigated with both a raw and an annealed thin sheet material of 1050-H16 aluminum alloy. The main process parameters are considered to be the clearance and punch-die corner radius for the micro half-blanking process, and the remaining thickness, tip radius, and shape angle of the V-notch. In this study, finite element simulations are carried out to verify the manufacturing process with the mentioned process parameters. The ductile fracture criterion is also adopted to predict the fracture limit for each component. Furthermore, experimental investigations are included to verify the fracture limit predicted from the numerical approach. From the systematic approaches, it is confirmed that the fracture limit for the double safety structure is well predicted, and satisfies the required fracture limit.

369

Trigonal Ir9Al28, a new structure type and approximant to decagonal quasicrystals  

International Nuclear Information System (INIS)

During an investigation of the binary system Al-Ir, a new phase with composition Ir9Al28 was identified. After annealing at 780 deg. C, its structure was determined by single-crystal X-ray diffraction. Trigonal Ir9Al28 is the first representative of a new structure type with Pearson symbol hP236-14, a = b = 12.2864(4) A, c = 27.341(1) A, ? = 120 deg., space group P31c, no. 159. The crystal structure can be described likewise as stacking of eight puckered and flat layers with a sequence ...P0PFPP0piFiPi... along [0 0 1], as a six-layer stacking sequence along [1 0 0], or as packing of pseudo-Mackay icosahedra. The Ir substructure with pseudosymmetry P63/mmc resembles the V4Al23 structure type. Pentagonal columnar clusters running along [0 0 1] show close resemblance to decagonal quasicrystals with six-layer period along the 10-fold axis

370

New structure type in the mixed-valent compound YbCu4Ga8.  

Science.gov (United States)

The new compound YbCu(4)Ga(8) was obtained as large single crystals in high yield from reactions run in liquid gallium. Preliminary investigations suggest that YbCu(4)Ga(8) crystallizes in the CeMn(4)Al(8) structure type, tetragonal space group I4/mmm, and lattice constants are a = b = 8.6529(4) Å and c = 5.3976(11) Å. However, a detailed single-crystal XRD revealed a tripling of the c axis and crystallizing in a new structure type with lattice constants of a = b = 8.6529(4) Å and c = 15.465(1) Å. The structural model was further confirmed by neutron diffraction measurements on high-quality single crystal. The crystal structure of YbCu(4)Ga(8) is composed of pseudo-Frank-Kasper cages occupying one ytterbium atom in each ring which are shared through the corner along the ab plane, resulting in a three-dimensional network. The magnetic susceptibility of YbCu(4)Ga(8) investigated in the temperature range 2-300 K showed Curie-Weiss law behavior above 100 K, and the experimentally measured magnetic moment indicates mixed-valent ytterbium. Electrical resistivity measurements show the metallic nature of the compound. At low temperatures, variation of ? as a function of T indicates a possible Fermi-liquid state at low temperatures. PMID:23391136

Subbarao, Udumula; Gutmann, Matthias J; Peter, Sebastian C

2013-02-18

371

Molecular dynamics studies on the structural stability of wild-type dog prion protein.  

Science.gov (United States)

Prion diseases such as Creutzfeldt-Jakob disease, variant Creutzfeldt-Jakob diseases, Gerstmann-Sträussler-Scheinker syndrome, Fatal Familial Insomnia, Kuru in humans, scrapie in sheep, bovine spongiform encephalopathy (or 'mad-cow' disease) and chronic wasting disease in cattle are invariably fatal and highly infectious neurodegenerative diseases affecting humans and animals. However, by now there have not been some effective therapeutic approaches to treat all these prion diseases. In 2008, canine mammals including dogs (canis familials) were the first time academically reported to be resistant to prion diseases (Vaccine 26: 2601-2614 (2008)). Thus, it is very worth studying the molecular structures of dog prion protein to obtain insights into the immunity of dogs to prion diseases. This paper studies the molecular structural dynamics of wild-type dog prion protein. The comparison analyses with rabbit prion protein show that the dog prion protein has stable molecular structures whether under neutral or low pH environments. We also find that the salt bridges such as D177-R163 contribute to the structural stability of wild-type rabbit prion protein under neutral pH environment. PMID:21469747

Zhang, Jiapu; Liu, David D W

2011-06-01

372

Alternative conceptual design of a magnet support structure for plasma fusion devices of stellarator type  

International Nuclear Information System (INIS)

Engineering design of magnet coil support structures for plasma fusion devices of the stellarator type are at present an important task in stellarator hardware R and D activities. In particular this is one of the basic core components in developing the stellarator's line in view of a robust and reliable fusion reactor. Based on long time experience in design and structural analyses of stellarator magnet systems and their support structure, the authors are proposing in this paper an alternative conceptual design for the magnet support structure. This paper describes the basic assumptions that a conceptual design of a magnet support structure has to fulfil. In this context, essential experiences gathered during manufacturing and assembly of the magnet support structure for a current stellarator fusion device engineered at Max Planck Institute for Plasma Physics are taken into account. The concept provides flexibility in matters of readjustment and positional optimization of the magnet coils during the assembly phase and potentially during the operation. The flexibility during the assembly phase allows a simplification of technical requirements and performance criteria which may result in a reduction of costs and improved reliability of a stellarator based power device.

373

Structural parameters determining the transition temperature of tetragonal KH2PO4-type crystals  

Science.gov (United States)

A systematic study of the structural parameters determining the ferroelectric phase transition temperature Tc in tetragonal KH2PO4 (KDP)-type crystals MH2XO4 has been performed by searching the correlation between different structural parameters and Tc. It has been revealed that the transition temperature is determined not only by the hydrogen-bond distance R, as reported earlier, but also by the distortion of XO4 (via O-X-O angle ?1) and the packing of M and XO4 along the c axis (via the rotation angle ? around the c axis); ?1 reflects the dipole moment of XO4 and ? may influence the amplitude of optical vibration of M and XO4. The contribution of each structural part to the transition temperature Tc in the tetragonal KDP family has been revealed in a comprehensive way for ferroelectrics.

Ichikawa, M.; Amasaki, D.; Gustafsson, T.; Olovsson, I.

2001-09-01

374

Structural and spectroscopic characteristics of two new dibenzylbutane type lignans from Taxus baccata L.  

Science.gov (United States)

Chromatographic separation of chloroform extracts of the heartwood of Taxus baccata L. has yielded two new dibenzylbutane type lignans, together with a known lignan. Their structures were established as 3'-demethylisolariciresinol-9'-hydroxy isopropylether ( 1) and 3-demethylisolariciresinol ( 2) and isolariciresinol ( 3) on the basis of 1D- and 2D-NMR spectroscopic analysis. Compounds 1 and 2 were identified as new lignans of isolariciresinol derivatives. Compound 1 is the first lignan with a hydroxyisopropyl group at C-9'. Molecular mechanic calculations of these compounds were carried out by using MM3 program. Furthermore, the conformations of these three compounds were computed with the semi-empirical molecular orbital methods AM1 and PM3 by using X-ray crystal structure results of similar compounds. So, three-dimensional, the most probable structure of these compounds were obtained, compared and discussed.

Erdemoglu, N.; Sener, B.; Ozcan, Y.; Ide, S.

2003-08-01

375

Moessbauer study of two different aged rock types in the Vredefort structure, South Africa  

Energy Technology Data Exchange (ETDEWEB)

The Vredefort Structure in South Africa was recently inscribed into the list of World Heritage sites as the oldest and largest recognised impact structure on earth. Due to upliftment of more than 30 km of the Archaean basement core and subsequent exposure of the deeply eroded central portion of the crater a unique opportunity exists to study rocks of the crust, especially those that have undergone recrystallization due to various thermal metamorphic events over time. Two rock types occurring in the central uplifted part of the impact structure were studied. One was a typical Archaean iron formation of sedimentary origin. The other rock studied, adjacent to this much older rock, is a homogeneous, medium grained recrystallized norite of immediately pre- or post-impact age, indicating a possible mafic igneous activity related to impact. Microscopy, XRD and Moessbauer analyses were performed on both samples.

Waanders, F. B., E-mail: chifbw@puk.ac.za; Brink, M. C.; Bisschoff, A. A. [North-west University, School of Chemical and Minerals Engineering (South Africa)

2005-11-15

376

Current limiting characteristics of transformer type HTS superconducting fault current limiter with rewound structure  

International Nuclear Information System (INIS)

A transformer type SCFCL of HTS wire with rewound structure has a primary coil of BSCCO wire connected to a power system and has a secondary coil of also BSCCO wire short-circuited. Both HTS coils were wound co-axially with rewound structure to get longer wire, that is, larger resistance at the normal state. The rewound structure offers greater flexibility in the design of the inductance and resistance of the SCFCL. It was experimentally confirmed that the SCFCL gives an inductive limiting impedance for smaller fault current while the only secondary wire transits to normal state and for larger fault current, it can give a resistive component additively by the normal transition of the primary wire. The current limiting characteristics of the proposed SCFCL were discussed by experimental results. Excellent recovery characteristics, that is, the recovery under load operation and repetitive limiting operation were confirmed experimentally.

377

Sloshing and fluid-structure interaction in a 400-MWe pool-type advanced LMR 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 to the fast reactor system

378

Thermal expansivity correlations for refractory materials with the NaCl-type structure  

International Nuclear Information System (INIS)

An empirical method developed by the author for predicting thermal expansivities for hard materials to about ± 10%, is extended to relatively softer materials - phosphides, sulphides, and selenides. To avoid the complexity of different structures, a common structure, the NaCl-type structure, has been maintained in carrying out the study. Thermal expansivity is correlated with two parameters: the atomization energy of the solid, which is taken as a measure of bonding strength; and the Knoop microhardness, which is taken as a measure of the steepness of the extension side of the potential energy well. An equation for the volume thermal expansivity is given. Included also is an evaluation of the thermodynamic stabilities of ThP and UP. (author)

379

Structural Approach and Luminescence Properties of La 1/6Pb 1/3Zr 2(PO 4) 17/6(SiO 4) 1/6:Eu 3+  

Science.gov (United States)

Rare earth phosphosilicates (Li1-xEux)1/6Pb1/3Zr2(PO4)17/6(SiO4)1/6 0?x?1 have been synthesized via a sol-gel route. The powder X-ray diffraction has been analyzed with the Nasicon-type structure. The Rietveld analysis of the structure performed in space group Roverline3 shows a statistical distribution of ions La3+, Eu3+, and Pb2+ over the positions 3a (occupation 10%) and 3b (occupation 90%) of the so-called M1 site. In agreement with these results, the Eu3+ luminescence analysis in these phases exhibits two sites for Eu3+, both are noncentrosymmetric, revealing a local disorder in the compounds, which is also supported by the inhomogeneous broadening of the emission lines. The luminescence characteristics of this family of silicates have been investigated for various x values. Under excitation at 254 nm, the distinct emissions of Pb2+ and of Eu3+ are observed. The excitation of Eu3+ ions occurs directly via the charge transfer state or after Pb2+?Eu3+ energy transfer. Concentration quenching of the Eu3+ emission is also investigated.

Bakhous, K.; Cherkaoui, F.; Benabad, A.; Jouhari, N. El; Savariault, J. M.; Dexpert-Ghys, J.

1999-09-01

380

Ensembled support vector machines for human papillomavirus risk type prediction from protein secondary structures.  

Science.gov (United States)

Infection by the human papillomavirus (HPV) is regarded as the major risk factor in the development of cervical cancer. Detection of high-risk HPV is important for understanding its oncogenic mechanisms and for developing novel clinical tools for its diagnosis, treatment, and prevention. Several methods are available to predict the risk types for HPV protein sequences. Nevertheless, no tools can achieve a universally good performance for all domains, including HPV and nor do they provide confidence levels for their decisions. Here, we describe ensembled support vector machines (SVMs) to classify HPV risk types, which assign given proteins into high-, possibly high-, or low-risk type based on their confidence level. Our approach uses protein secondary structures to obtain the differential contribution of subsequences for the risk type, and SVM classifiers are combined with a simple but efficient string kernel to handle HPV protein sequences. In the experiments, we compare our approach with previous methods in accuracy and F1-score, and present the predictions for unknown HPV types, which provides promising results. PMID:19185855

Kim, Sun; Kim, Jeongmi; Zhang, Byoung-Tak

2009-02-01

 
 
 
 
381

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

382

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.

383

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

Science.gov (United States)

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

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

2015-02-15

384

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

385

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

386

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

387

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

Energy Technology Data Exchange (ETDEWEB)

Several species of bacteria 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 facilitated by filamentous fibers that are referred to as bacterial nanowires. These nanowires belong to the type IVa family of pilin proteins and are mainly comprised of one subunit protein, PilA. Here, we report the high resolution solution nuclear magnetic resonance (NMR) structure of the PilA protein from G. sulfurreducens determined in detergent micelles. The protein is over 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.

Reardon, Patrick N.; Mueller, Karl T.

2013-10-11

388

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

389

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

International Nuclear Information System (INIS)

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

390

Structural and energetic determinants of adhesive binding specificity in type I cadherins.  

Science.gov (United States)

Type I cadherin cell-adhesion proteins are similar in sequence and structure and yet are different enough to mediate highly specific cell-cell recognition phenomena. It has previously been shown that small differences in the homophilic and heterophilic binding affinities of different type I family members can account for the differential cell-sorting behavior. Here we use a combination of X-ray crystallography, analytical ultracentrifugation, surface plasmon resonance and double electron-electron resonance (DEER) electron paramagnetic resonance spectroscopy to identify the molecular determinants of type I cadherin dimerization affinities. Small changes in sequence are found to produce subtle structural and dynamical changes that impact relative affinities, in part via electrostatic and hydrophobic interactions, and in part through entropic effects because of increased conformational heterogeneity in the bound states as revealed by DEER distance mapping in the dimers. These findings highlight the remarkable ability of evolution to exploit a wide range of molecular properties to produce closely related members of the same protein family that have affinity differences finely tuned to mediate their biological roles. PMID:25253890

Vendome, Jeremie; Felsovalyi, Klara; Song, Hang; Yang, Zhongyu; Jin, Xiangshu; Brasch, Julia; Harrison, Oliver J; Ahlsen, Goran; Bahna, Fabiana; Kaczynska, Anna; Katsamba, Phinikoula S; Edmond, Darwin; Hubbell, Wayne L; Shapiro, Lawrence; Honig, Barry

2014-10-01

391

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

DEFF Research Database (Denmark)

We present a high-order nodal Discontinuous Galerkin Finite Element Method (DG-FEM) solution based on a set of highly accurate Boussinesq-type equations for solving general water-wave problems in complex geometries. A nodal DG-FEM is used for the spatial discretization to solve the Boussinesq equations in complex and curvilinear geometries which amends the application range of previous numerical models that have been based on structured Cartesian grids. The Boussinesq method provides the basis for the accurate description of fully nonlinear and dispersive water waves in both shallow and deep waters within the breaking limit. To demonstrate the current applicability of the model both linear and mildly nonlinear test cases are considered in two horizontal dimensions where the water waves interact with bottom-mounted fully reflecting structures. It is established that, by simple symmetry considerations combined with a mirror principle, it is possible to impose weak slip boundary conditions for both structured and general curvilinear wall boundaries while maintaining the accuracy of the scheme. As is standard for current high-order Boussinesq-type models, arbitrary waves can be generated and absorbed in the interior of the computational domain using a flexible relaxation technique applied on the free surface variables.

Engsig-Karup, Allan Peter; Hesthaven, Jan

2008-01-01

392

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

393

On the structure type of Na10MgTi10O26  

International Nuclear Information System (INIS)

The analysis of the Weissenberg photographs from the solid electrolyte of the composition Na8+xMgx/2Ti11-x/2O26 showed that the superstructural reflections and the apparent change of the symmetry from monoclinic to orthorhombic are caused by twinning with the specific ratio of its unit-cell parameters, b/4a?cos ?. The analysis of the interatomic distances and bond valences allowed the refinement of the compound composition (x?1.5) and the establishment of a position occupied mainly by magnesium. The X-ray phase analysis of quaternary oxide systems has showed that the structure type under question can be stabilized not only by Mg2+, Zn2+, and Sc3+ ions, but also by a manganese ion, Mn2+, but cannot be stabilized by smaller (Ti3+,V3+...Ni2+) cations. The mobility of all the sodium ions (even those located in the narrowest tunnels of the structure) is confirmed by almost complete substitution of these ions by silver ions occurring during ion exchange, by their substitution by lithium, and sodium extraction during Mn2+ oxidation. The oxygen coordination and rather rare occurrence of the structure type under question are discussed

394

Structural Characterization of Lignin in Wild-type versus COMT Down-regulated Switchgrass  

Directory of Open Access Journals (Sweden)

Full Text Available This study examined the chemical structural characteristics of cellulolytic enzyme lignin isolated from switchgrass focusing on comparisons between wild-type control and caffeic acid 3-O-methyltransferase (COMT down-regulated transgenic line. Nuclear magnetic resonance (NMR techniques including 13C, 31P, and two-dimensional 13C-1H heteronuclear single quantum coherence (HSQC as well as gel permeation chromatography (GPC were employed. Compared to the wild-type, the COMT down-regulated transgenic switchgrass lignin demonstrated a decrease in syringyl (S: guaiacyl (G ratio and p-coumarate:ferulate ratio, an increase in relative abundance of phenylcoumaran unit, and a comparable content of total free phenolic OH groups along with formation of benzodioxane unit. In addition, COMT down-regulation had no significant effects on the lignin molecular weights during its biosynthesis process.

ArthurRagauskas

2014-01-01

395

Numerical analysis of the discharge structures in non-equilibrium disk type MHD generator  

International Nuclear Information System (INIS)

Discharge structures in the channel of a non-equilibrium disk type MHD generator have been studied by two-dimensional dynamic numerical analysis. (1) In the disk type Hall generator, discharge in the channel is non-uniform due to plasma ionization instability. (2) At low magnetic inductions, the discharge is non-uniform due to incomplete plasma seed ionization. At high magnetic inductions, it becomes uniform due to the complete seed ionization. (3) As compared with the linear channel Faraday generator, the disk channel Hall generator with internally short-circuited Faraday current is capable of high-efficiency plasma heating and so of suppressing the plasma ionization instability at low magnetic induction. (4) With decrease of the load resistance, the electron temperature lowers and also the electron density. (Mori, K.)

396

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.)

397

The structural transition from NaCl to CsCl type in cesium hydride  

International Nuclear Information System (INIS)

The CsH volume is measured in dependence on pressure up to 35 kbar. A structural NaCl to CsCl type transition associated with a volume jump of 8.6% is found at a pressure of about 6.5 kbar. The T-P phase diagram of CsH is plotted in the temperature range 200 to 525 K. The high pressure phase at liquid nitrogen temperature remains metastable down to atmospheric pressure. The lattice parameter of this phase is a=3.820 A at 100 K and atmospheric pressure, the lattice parameter of the initial (NaCl type) phase is a=6.365 A under the same conditions. (author)

398

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

Science.gov (United States)

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

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

2015-01-01

399

Structural and electronic properties of type-I and type-VIII Ba{sub 8}Ga{sub 16}Sn{sub 30} clathrates under compression  

Energy Technology Data Exchange (ETDEWEB)

The total energy and electronic structures for type-I ({beta} phase) and type-VIII ({alpha} phase) Ba{sub 8}Ga{sub 16}Sn{sub 30} 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 {beta}{yields}{alpha} phase transition can not occur under hydrostatic pressure. The band structures show that the type-I and type-VIII Ba{sub 8}Ga{sub 16}Sn{sub 30} are indirect semiconductors with band gaps of 0.24 eV and 0.19 eV, respectively. The results suggested that type-I clathrate Ba{sub 8}Ga{sub 16}Sn{sub 30} 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 {beta}-phase, but it is not the case for {alpha}-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 {beta}-phase and the increase of the band gap of {alpha}-phase, indicating that the pressure effect can play an important role in the magnitude of the TE power.

Li, D.C. [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Fang, L., E-mail: fangliangcqu@yahoo.com.cn [Department of Applied Physics, Chongqing University, Chongqing 400044 (China); Deng, S.K.; Kang, K.Y.; Shen, L.X. [Education Ministry Key Laboratory of Renewable Energy Advanced Materials and Manufacturing Technology, Yunnan Normal University, Kunming, Yunnan Province, 650092 (China); Wei, W.H.; Ruan, H.B. [Department of Applied Physics, Chongqing University, Chongqing 400044 (China)

2012-04-15

400

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.

 
 
 
 
401

Thermoelectric and transport properties of sintered n-type K8Ba16Ga40Sn96 with type-II clathrate structure  

Science.gov (United States)

This clathrate had a maximum dimensionless figure-of-merit, ZT, of 0.93 at 637 K, which was slightly higher than that of 0.83 for the sintered type-VIII clathrate Ba8Ga16Sn30. We investigated the high-temperature thermoelectric properties, transport properties, electronic structures, and thermal stabilities of the clathrates. The type-II clathrate was found to be superior to the type-VIII clathrate as a thermoelectric material; it had a high thermal stability and melting point, 859 K, high mobility, 141 cm2V-1s-1 at 300 K, because of its low inertial mass, and low high-temperature lattice thermal conductivity, approximately 4 mW cm-1K-1, resulting from a larger unit cell and weaker bipolar thermal conduction. We discuss these properties in terms of the electronic structure and the differences between the two types of clathrate.

Koda, Shota; Kishimoto, Kengo; Akai, Koji; Asada, Hironori; Koyanagi, Tsuyoshi

2014-07-01

402

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

International Nuclear Information System (INIS)

Full text:The following oxides have been investigated: ortho ferrites (OF) LnFe2/3Mo1/3O3 (Ln = La, Ce, Pr, Nd), and oxygen-deficient perovskites with various structure types Pr4BaCu4FeOl3-? (? = 0, 0.5, type 4-1-5), Ln8-ySryCu8-xFexO20 (Ln = La, Nd, Pr, y=1.6-4, x = 1.6-3, type 8-8-20) and YBa2yLayCu3-xFexO7-?, Y1yCayBa2-yLayCu3-xFexO7-? (y = 0.25, 0.5, x = 0.06, 0.12, ?? 0.05, type 1-2-3). All investigated compounds are given by Institute of Chemistry of Ural branch of RAS (Ekaterinburg, G.V. Bazuev's laboratory). The Moessbauer spectroscopy on an isotope 57Fe was the basic method of researches. At some stages of researches as an additional method also X-ray analysis has been used. All considered types of perovskite-related structures are characterized by the general attribute of relationship - presence of layers, packages or skeletons from connected by tops octahedrons MeO6 (in our case Me = Cu, Fe, Mo) or their rests as pyramids MeO5, squares MeO4 and dumbbells MeO2 in oxygen-deficient compounds. The selection of samples (sequence of their research) was made so, that each subsequent structure row has the bigger 'deficiency' of oxygen in recalculation on acy' 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

403

New procedure to evaluate structural pipe-type element resource from specimen testing results  

International Nuclear Information System (INIS)

A new procedure is reported to study the supporting ability of structural pipe-type elements using a peculiar specimen of biconvex-concave shape whose working sites contain inner and outer surfaces of the pipe. Compression of the test results obtained by using both existing and developed procedures has shown that damages of surface layers obtained during production of the pipe and its operation decrease the pipe durability by 10-20%. It should be considered when appointing safe terms for further operation of pipe-lines

404

Reduction of energy-loss 'ghost structures' observed in electrostatic deflection type electron analysers  

International Nuclear Information System (INIS)

Ghost lines due to electron reflections occurring on the wall plates of an electrostatic deflection type electron analyser are observed and studied as a function of electron intensity and energy, in the kinetic energy range 25-40 keV. The model by Froitzheim et al. is found to be in good agreement with our measurements. A new method, based on the angular separation of the ghost beam from the analysed beam, is used to reduce the ghost structure intensity by a factor of about 300. (orig.)

405

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.

406

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

Energy Technology Data Exchange (ETDEWEB)

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.

Stalin, S. [Centre for Nonlinear Dynamics, School of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India); Senthilvelan, M., E-mail: velan@cnld.bdu.ac.in [Centre for Nonlinear Dynamics, School of Physics, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu (India)

2011-10-17

407

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

Directory of Open Access Journals (Sweden)

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

408

Reflection-free complex absorbing potential for electronic structure calculations: Feshbach type autoionization resonance of Helium  

International Nuclear Information System (INIS)

This work represents the first successful application of reflection-free complex absorbing potential (RF-CAP) method to the study of resonances in many-electron systems. The present work introduces a systematic way for implementing RF-CAP for the electronic structure calculations using Gaussian basis sets. The method is applied to study the lowest 1S Feshbach type autoionization resonance of He. It is shown that in order to be able to introduce the RF-CAP close to the nucleus, where the electron-nucleus Coulomb attraction force is not negligible, the RF-CAP should be supplemented by a weak static field

409

Structure of branches in infrared-active fundamental-type bands of spherical-top molecules  

International Nuclear Information System (INIS)

In the absence of strong accidental resonance, the detailed energy-level structures of all Q branches of infrared-active fundamental-type bands in spherical-top molecules are prescribed, in the first approximation, by the value of the single parameter, ? = ?/g, where ? = ?B/sub eff/sup Q/ and g is the tetrahedral or octahedral splitting constant. The Q branches of several heavy and light spherical tops are examined in this context, using energy-level diagrams, level cluster analysis, and computer graphics to simulate the superpositions of hundreds of absorption lines

410

Effect of culture conditions on the structure of Streptococcus pneumoniae type 19A(57) capsular polysaccharide.  

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The structural modifications and immunochemical activities of several Streptococcus pneumoniae type 19A polysaccharide (PS) preparations have been studied by sugar compositional analysis and immunodiffusion. The 19A PS preparations Lab-A-1 and Lab-A-3 and one PS isolated from 19A strain OB contained fucose (Fuc) and galactose (Gal) in addition to rhamnose (Rha) and glucose (Glc). In contrast, 19A PSs Lab-A-2 and Lab-B contained only Rha and Glc. Despite their different sugar compositions, the...

Lee, C. J.; Fraser, B. A.; Boykins, R. A.; Li, J. P.

1987-01-01

411

Hydrodynamic constraints on the radial structure of late-type galaxy disks  

International Nuclear Information System (INIS)

Hydrodynamic constraints or driving forces that determine steady disk gas radial distributions are discussed, and observed gas distributions in late-type disks and correlations with disk rotation curves are analyzed. Evidence for quasi-steady states with radial gas flow is examined, and gas consumption rates and stellar density profiles are discussed, as are models of steady states with radial flows and more extreme driven disks. The results indicate that the radial structure of a gas-rich disk can be simply and consistently accounted for as an azimuthally averaged hydrodynamic steady state in a fixed gravitational potential. 83 refs

412

The Structure of Rapidly Rotating Late-Type Spiral Galaxies: I. Photometry, HI and Optical Kinematics  

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We present I-band photometry, long-slit optical spectroscopy, and new aperture synthesis HI observations for eight late-type spirals with rotation velocities in the range 243 km/s < V_{rot} < 308 km/s. The sample will be used to study the structure and angular momentum of disks at the high-mass end of the spiral galaxy population; here we discuss the basic properties of these ``fast rotators'', and derive hybrid optical/HI rotation curves for each. Despite the presence of HI...

Spekkens, K.; Giovanelli, R.

2006-01-01

413

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

414

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)

415

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

416

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 aFe-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

417

Sequence and structural characterization of Trx-Grx type of monothiol glutaredoxins from Ashbya gossypii.  

Science.gov (United States)

Glutaredoxins are enzymatic antioxidants which are small, ubiquitous, glutathione dependent and essentially classified under thioredoxin-fold superfamily. Glutaredoxins are classified into two types: dithiol and monothiol. Monothiol glutaredoxins which carry the signature "CGFS" as a redox active motif is known for its role in oxidative stress, inside the cell. In the present analysis, the 138 amino acid long monothiol glutaredoxin, AgGRX1 from Ashbya gossypii was identified and has been used for the analysis. The multiple sequence alignment of the AgGRX1 protein sequence revealed the characteristic motif of typical monothiol glutaredoxin as observed in various other organisms. The proposed structure of the AgGRX1 protein was used to analyze signature folds related to the thioredoxin superfamily. Further, the study highlighted the structural features pertaining to the complex mechanism of glutathione docking and interacting residues. PMID:23515490

Yadav, Saurabh; Kumari, Pragati; Kushwaha, Hemant Ritturaj

2013-01-01

418

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

419

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

420

Structural Response of P2-Type NaxMnO2 against Na+ Intercalation  

Science.gov (United States)

P2-type NaxMnO2 (P63/mmc, Z = 2) with a layered rock-salt structure is a promising cathode material for low-cost sodium ion secondary batteries (SIBs). Here, we performed an ex situ synchrotron radiation x-ray structural analysis of NaxMnO2 (0.43 ? x ? 0.71) against Na+ concentration (x). We found that the thicknesses (dNaO\\scale70%2) of the NaO2 layer is nearly independent of x, in a sharp contrast to the rapid decrease observed in isostructural NaxCoO2. In addition, the site energy differences [?? = ?1 - ?2; ?1 (?2) is the site energy at Na1 (Na2)] in NaxMnO2 are much smaller than those in NaxCoO2. These observations are interpreted in terms of the screening effect of the Na+ charge in NaxMnO2.

Shimono, Takahiro; Tanabe, Daiki; Kobayashi, Wataru; Moritomo, Yutaka

2013-08-01

 
 
 
 
421

Ag-2223 (Bi) tapes structure and superconducting properties in dependence of initial powder type  

International Nuclear Information System (INIS)

An investigation was carried out into the critical properties and specific features of structure in composite tapes with a core material of composition 2:2:2:3.2 in bismuth system produced by freeze drying technique and taken at different stages of the synthesis process. Consideration is given to powder behavior in the process of cold drawing and rolling of composite tapes followed by heat treatment under similar condition as well as to evolution of microstructure, specificity of texture and kinetics of superconducting phase formation. It is shown that the most favorable type of structure in heat treated superconductors develops when core material powder is used in the form of a precursor consisting of fine mixture of dioxides and ''2212'' phase resultant from calcination within the interval 750--800 C. The critical current density more than 104 A/cm2 at 77 K was achieved in the composite tapes. The results of testing for small coils are presented

422

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

International Nuclear Information System (INIS)

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

423

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

424

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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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 ...

Elahi-Moghaddam Zohreh; Behnam-Rassouli Morteza; Mahdavi-Shahri Naser; Hajinejad-Boshroue Roya; Khajouee Elaheh

2013-01-01

425

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

International Nuclear Information System (INIS)

Highlights: • Tb–Zn substituted Ca0.5Ba0.5Fe12O19 samples exhibit single magnetoplumbite phase. • Lattice parameters a and c have increasing values. • Coercivity can be tuned at lower substitution level • Crystallites size was found in the range 18–25 nm by TEM and by Scherrer formula. • These hexa-ferrites are suitable for microwave devices and magnetic recording media. -- Abstract: Effect of TbZn substitution on the structural and magnetic properties of Ca0.5Ba0.5?xTbxZnyFe12?yO19, (x = 0.00–0.10; y = 0.00–1.00) ferrites prepared by sol–gel auto combustion is reported. The synthesized samples were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Vibrating Sample magnetometery. The X-ray diffraction analysis confirmed single phase M-type hexa-ferrite structure. The lattice parameters were found to increase as TbZn contents increases, which is attributed to the ionic sizes of the implicated cations. The TbZn seems to be completely soluble in the lattice. The results of scanning electron microscopy and transmission electron microscopy shows that the grain size decreases with increase of TbZn substitution. The coercivity values (1277–2025 Oe) of all samples lies in the range of M-type hexa-ferrite and indicate that an increase of anisotropy was achieved by substitution of TbZn, while the size of nanoparticles was drastically reduced between 18 and 25 nm. The increased anisotropy and fine particle size are useful for many applications, such as improving signal noise ratio of recording devices

426

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-03-15

427

Novel intermetallics with the Ca{sub 11} Ga{sub 7} structure type  

Energy Technology Data Exchange (ETDEWEB)

The binary alkaline earth (A{sup II}) trielides Ca{sub 11} Ga{sub 7} and Sr{sub 11} In{sub 7} crystallize with a singular structure type (cubic, space group Fm3-bar m, a{approx}1600 (A{sup II}=Ca) and 1700 (A{sup II}=Sr) pm, Z=8). Fourteen new ternary Ca and Sr mixed trielides and triel/tetrelides forming this structure type were synthesized from stoichiometric mixtures of the elements and characterized by single crystal X-ray diffraction. The structures exhibit isolated M(1) atoms (M(2)=Al, Ga, In, Sn, Pb) together with tetrahedral units [M(1){sub 4}], which are formed by the triel elements exclusively. Remarkably, one of the four crystallographically independent A{sup II} positions is - as in the pure element - coordinated by A{sup II} partners in a cuboctahedral arrangement. In the mixed M{sup III} /M{sup IV} compounds, a maximum phase range up to a maximum composition limit of A{sub 11}[M(1){sub 4}{sup III}][M(2){sup IV}]{sub 3} is observed, which nearly corresponds to an ionic description according to the Zintl concept (tetrahedral anions [M{sub 4}{sup III}]{sup 8-} isoelectronic to white phosphorus P{sub 4} besides isolated noble gas isosteric tetrelide anions [M{sup IV}]{sup 4-}). In the case of the Sr/In/Pb and some Ca compounds, the A position that is coordinated by alkaline earth atoms only is statistically substituted by the heavier triel/tetrel element. The stabilities and phase ranges of the compounds, which are influenced by geometric and electronic factors (investigated by FP-LAPW band structure calculations), are discussed.

Wendorff, Marco [Institut fuer Anorganische und Analytische Chemie, Universitaet Freiburg/Brsg. (Germany); Roehr, Caroline [Institut fuer Anorganische und Analytische Chemie, Universitaet Freiburg/Brsg. (Germany)], E-mail: caroline@ruby.chemie.uni-freiburg.de

2008-01-10

428

Probing large conformational rearrangements in wild-type and mutant spectrin using structural mass spectrometry.  

Science.gov (United States)

Conformational changes of macromolecular complexes play key mechanistic roles in many biological processes, but large, highly flexible proteins and protein complexes usually cannot be analyzed by crystallography or NMR. Here, structures and conformational changes of the highly flexible, dynamic red cell spectrin and effects of a common mutation that disrupts red cell membranes were elucidated using chemical cross-linking coupled with mass spectrometry. Interconversion of spectrin between closed dimers, open dimers, and tetramers plays a key role in maintaining red cell shape and membrane integrity, and spectrins in other cell types serve these as well as more diverse functions. Using a minispectrin construct, experimentally verified structures of closed dimers and tetramers were determined by combining distance constraints from zero-length cross-links with molecular models and biophysical data. Subsequent biophysical and structural mass spectrometry characterization of a common hereditary elliptocytosis-related mutation of ?-spectrin, L207P, showed that cell membranes were destabilized by a shift of the dimer-tetramer equilibrium toward closed dimers. The structure of ?L207P mutant closed dimers provided previously unidentified mechanistic insight into how this mutation, which is located a large distance from the tetramerization site, destabilizes spectrin tetramers and cell membrane integrity. PMID:24453214

Sriswasdi, Sira; Harper, Sandra L; Tang, Hsin-Yao; Gallagher, Patrick G; Speicher, David W

2014-02-01

429

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

Directory of Open Access Journals (Sweden)

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

Hermans Mieke CE

2012-07-01

430

UCr4C4 with filled MoNi4 type structure  

International Nuclear Information System (INIS)

The title compound was prepared by arc melting coldpressed pellets of the elemental components with subsequent annealing at both 800 oC or 1100 oC. UCr4C4 crystallizes tetragonal, space group I4/m, a = 0.79363(4)nm, c = 0.30754(3)nm, V = 0.19470nm3 with Z = 2 formula units per cell. The structure was determined from single-crystal X-ray data and refined to a residual of R = 0.027 for 16 variable parameters and 279 strucute factors. The positions of the metal atoms correspond to those of the MoNi4 type structure. The carbon atoms occupy octahedral vois formed by four chromium and two adjacent uranium atoms. Chemical bonding in UCr4C4 and in other interstitial compounds is briefly discussed. The average valence electron number of the metal atoms is usually greater for the unfilled (host) structure than for the corresponding filled structure. (Author)

431

Crystal structure of the bacterial type VI secretion system component TssL from Vibrio cholerae.  

Science.gov (United States)

The type VI secretion system (T6SS), commonly found in gram-negative bacteria, is responsible for exporting effector proteins. The T6SS has been reported to be cytotoxic to host cells. While the components and assembly of the T6SS complex have been largely assessed, structural data on T6SS components from virulent bacteria is remarkably insufficient. Here, we report the crystal structure of Vibrio cholerae TssL (VcTssL), a core component of T6SS. In spite of a relatively low sequence identity, the overall structure of VcTssL is largely similar to those from other bacterial homologs except for several differences found in local structural elements. A unique feature attributed to the C-terminal fragment of VcTssL is a crystallographic artifact. This incidental feature of VcTssL may provide insights into screening of molecular partners for the cytoplasmic domain of TssL. Additionally, our results may help in the design of molecular probes for a detailed understanding of the functional relationship between TssL and other T6SS components. PMID:25471186

Chang, Jeong Ho; Kim, Yeon-Gil

2014-12-01

432

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

433

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-01-01

434

A supramolecular double sulfate salt with a lamellar type: crystal structure and thermal behavior.  

Science.gov (United States)

The synthesis of a series of supramolecular double sulfate salts using transition metals and the aromatic amine ?-methylbenzylamine afforded an unexpected hybrid lamellar structure type. (C8H12N)2[M(H2O)4(SO4)2]·2H2O (M = Fe to Zn) crystallizes with a monoclinic structure (S.G. P21/n), with a significant interlamellar distance of more than 16 Å. While comparable to common clay materials, the crystal structure is actually supramolecular; in particular, the mineral layer is built from hydrogen bonds only. The interlayer space is filled with aromatic amines that form chains through C-H···? interactions. The thermal study of all metal compounds revealed good stability of the filled compounds up to 200 °C. The dehydration proceeds differently according to the metal incorporated into the structure. In particular, the stepped release of water drastically modifies the interlayer space, which is able to vary from 14.8 to 18.8 Å, in an opposite way for the Zn-related compound compared to other metals. PMID:24533651

Kammoun, Omar; Bataille, Thierry; Lucas, Anita; Dorcet, Vincent; Marlart, Isabelle; Rekik, Walid; Naïli, Houcine; Mhiri, Tahar

2014-03-01