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1

Polarization phenomena in romboedric structures of NASICON  

International Nuclear Information System (INIS)

[en] 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)

2006-01-01

2

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

International Nuclear Information System (INIS)

[en] 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[ru] ?? ????????????? ????????????? ?????? ???????? ?????? ? ??????????????? ????????? ???????? ????????? K0.52(Mn0.47Zr0.45)2(MoO4)3. ??????? ???????????? ??????????? ??????: a = b = 9.474(1), c = 24.371(4) A, Z =6, ???? = 3.337 ?/??3, ??. ??. R3-barc. ??????????????? ????????? ???????????? ????? ?????????? ????????? ?????? ?? ????????? (Mn, Zr)O6 ? ?????????? MoO4 ? ?????? ???????????? ?????????, ? ??????? ??????? ???????? ??????????? ????? ?????, ? ???????? ? ???????????? ???? Nasicon'?

2003-01-01

3

Trivalent praseodymium ion conducting solid electrolyte composite with NASICON type structure  

International Nuclear Information System (INIS)

[en] 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

2004-07-28

4

Trivalent praseodymium ion conducting solid electrolyte composite with NASICON type structure  

Energy Technology Data Exchange (ETDEWEB)

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

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

2004-07-28

5

New trivalent ion conducting solid electrolyte with the NASICON type structure  

International Nuclear Information System (INIS)

[en] 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

2004-10-06

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)

[en] 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 case of Fe-doped materials this transition was not detected.Additionally, the correlation between the composition, microstructure and electrical properties was studied

2005-01-01

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)

[en] 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)

2004-01-01

11

The crystal structure of a nonstoichiometric nasicon  

Energy Technology Data Exchange (ETDEWEB)

The crystal structure of a nonstoichiometric NASICON prepared from a hydrothermally synthesized precursor phase was solved by means of Xray powder and neutron powder diffraction methods. The NASICON phase is monoclinic with unit cell parameters, from Rietveld refinement of the neutron data, of a = 15.6209(8), b = 9.0326(5), c = 9.2172(5)A, ..beta.. = 123.67(1)A, V = 1082.5A/sup 3/. The space group is C2/c with Z = 4. The structure is essentially that proposed earlier by Hong, but the nonstoichiometry results from replacement of part of the Zr/sup 4 +/ by Na/sup +/. Refinement of site occupancies coupled with the requirement of overall charge balance yields the formula Na /sub 2.88/ (Na /sub 0.32/ Zr /sub 1.68/ )Si /sub 1.84/ P /sub 1.16/ O /sub 11.54/ which also agrees well with analytical data. Only 20% of the Na1 sites are occupied, but 80% of the Na3 sites are filled. This structure provides a framework from which to rationalize the many reports in the literature that NASICON can only be prepared with difficulty by high temperature solid state reactions.

Rudolf, F.; Clearfield, A.; Jorgensen, J.D.; Subramanian, M.A.

1985-06-01

12

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

Science.gov (United States)

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

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

2013-03-05

13

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

UK PubMed Central (United Kingdom)

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.

Senguttuvan P; Rousse G; Arroyo y de Dompablo ME; Vezin H; Tarascon JM; Palacín MR

2013-03-01

14

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

Science.gov (United States)

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-xLax/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-xLax/3?2x/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¯c), while at lower temperature, their structure distorts to a triclinic form (s.g. C 1¯), as observed for LiZr2(PO4)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 La1/3Zr2(PO4)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 Li1-xLax/3Zr2(PO4)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

15

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

International Nuclear Information System (INIS)

[en] 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 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)

2007-01-01

16

An EXAFS Investigation on Copper(I-II) Related Nasicon-Type Phosphates  

Science.gov (United States)

An extended X-ray absorption fine structure study at the copper K-edge of Nasicon-type phosphates with formulas Cu1M2(PO4)3 (M = Ti, Zr), A1-xCuIxZr2(PO4)3 (0 Nasicon structure. In contrast, for the copper(II) phosphates, the Cu2+ ions are surrounded by four oxygen atoms at about 1.95 Å. Copper distribution in these various materials is discussed in relation to structural parameters.

Fargin, E.; Bussereau, I.; Olazcuaga, R.; Le Flem, G.; Cartier, C.; Dexpert, H.

1994-09-01

17

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 Roverline{3}. The structure is composed of PO4 tetrahedra (1 symmetry) and two slightly distorted SnO6 octahedra, both with 3. symmetry, which are...

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

18

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, w...

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

19

Structural and Luminescent Properties of a Nasicon-Type Phosphate CuI0.5MnII0.25Zr2(PO4)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 R3) 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

20

Synthesis of NASICON-type lithium zirconium phosphate  

International Nuclear Information System (INIS)

[en] 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[ru] ???????? ?????????????????????? ? ?????????????? ???????? ??????????? ?????????? ???????????, ??????????? ? ???????? ??????? ??????? ?????-???????? (LiZr2(PO4)3) ?? ?????????? ???????. ????????, ??? ??? ?????? ????? ??????? 3Zr(HPO4)2·H2O+Li2CO3+ZrO2 ???????????? ???? ??????? ?????????? ??? ??? 600 ???? ?. ?????? ?????????? ????????? ??????????? ???????? ? ????????????? ??????????? ??????????? ???????? ? ???????????????? ??????? ????? ?????????? ????????? ??? ??????????. ?????? ?????????????? ???????????????? ???? ??????? ?????????? ???? ???? 1100 ???? ?. ???????? ?????????? LiZr2(PO4)3 ??????? ?????? ??? ????????????? ??????????????? ????? ???????

2004-01-01

 
 
 
 
21

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

22

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

Science.gov (United States)

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 pr...

G. J. Sevigny M. S. Fountain S. Balagopal S. Bhavaraju

2009-01-01

23

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

24

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

International Nuclear Information System (INIS)

[en] 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

2009-01-01

25

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

26

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

UK PubMed Central (United Kingdom)

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.

Zhao D; Li F; Qiu S; Jiao J; Ren J

2011-05-01

27

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.

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

2011-01-01

28

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

2011-04-29

29

RbSn2(PO4)3, a NASICON-type phosphate  

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Full Text Available 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 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(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.

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

2011-01-01

30

Raman and infrared spectra of some chromium Nasicon-type materials: Short-range disorder characterization  

Science.gov (United States)

The infrared and Raman spectra of the Nasicon-type chromium systems are found to be very sensitive to the composition and to the nature of the metallic ions. The frequency shift of the infrared active modes involving the metallic ions is correlated to the modification of the crystal field around these ions. The static short-range disorder, particularly characterized from the Raman spectra, is essentially interpreted in terms of Na+ ion site occupation change vs the composition and the temperature.

Barj, M.; Lucazeau, G.; Delmas, C.

1992-09-01

31

NASICON-type Na3V2(PO4)3  

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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 s...

Zatovsky, Igor V.

32

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...

Igor V. Zatovsky

33

Synthesis and electric conductivity of solid electrolyte of NASICON type  

International Nuclear Information System (INIS)

[en] 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

1988-01-01

34

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

International Nuclear Information System (INIS)

[en] 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.)

1989-05-15

35

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

36

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

UK PubMed Central (United Kingdom)

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.

Patil V; Patil A; Yoon SJ; Choi JW

2013-05-01

37

Li sub 3 minus x Ti sub 2 (PO sub 4 ) sub 3 (O le x 1): A new mixed valent titanium(III/IV) phosphate with a NASICON-type structure  

Energy Technology Data Exchange (ETDEWEB)

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

Wang, Shumin; Hwu, Shioujyh (Rice Univ., Houston, TX (USA))

1991-02-01

38

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 R c and is identical to that of ?-NASICON. The...

Hatert, Frédéric

39

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 heter...

Frédéric Hatert

40

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

International Nuclear Information System (INIS)

[en] 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

1987-01-01

 
 
 
 
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

beta. -Zr/sub 2/(PO/sub 4/)/sub 2/SO/sub 4/: a zirconium phosphato-sulfate with a Sc/sub 2/(WO/sub 4/)/sub 3/ structure. A comparison between garnet, nasicon, and Sc/sub 2/(WO/sub 4/)/sub 3/ structure types  

Energy Technology Data Exchange (ETDEWEB)

The single-phase compound ..beta..-Zr/sub 2/(PO/sub 4/)/sub 2/SO/sub 4/ has been prepared by refluxing zirconium phosphate gel in sulfuric acid at 200/sup 0/C. It crystallizes in the orthorhombic system, space group Pbcn with a = 12.3742(9), b = 8.867(2), c = 8.951(1) A, Z = 4. The structure was determined from 560 reflections collected on a Nonius CAD4 automatic diffractometer with MoK/sub alpha/ radiation. The final R index and weighted R/sub w/ index are 0.049 and 0.062 respectively. The structure, built up from ZrO/sub 6/ octahedra and PO/sub 4/ and SO/sub 4/ tetrahedra linked by corners, is isotypic with that of Sc/sub 2/(WO/sub 4/)/sub 3/ and is closely related to that of garnet and nasicon. In these three structure types the arrangements of octahedral cations are very similar.

Piffard, Y.; Verbaere, A.; Kinoshita, M.

1987-11-01

43

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

UK PubMed Central (United Kingdom)

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.

Hatert F

2009-01-01

44

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

2009-03-19

45

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

2010-01-27

46

NASICON-type Na(3)V(2)(PO(4))(3).  

UK PubMed Central (United Kingdom)

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.

Zatovsky IV

2010-01-01

47

NASICON-type Na3V2(PO4)3  

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(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 (overline{3}. symmetry) and eightfold for the second (.2 symmetry) Na+ cation.

Igor V. Zatovsky

2010-01-01

48

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.

Zatovsky, Igor V.

2010-01-01

49

A new Nasicon-type phosphate Co{sub 0.5}Ti{sub 2}(PO{sub 4}){sub 3}. 1: Elaboration, optical and magnetic properties  

Energy Technology Data Exchange (ETDEWEB)

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 R{bar 3} or the R32 space groups. The atomic arrangement is a three-dimensional framework formed by PO{sub 4} tetrahedra sharing corners with TiO{sub 6} octahedra. Co{sup 2+} is located in half of the antiprism M(1) sites in a centered (R{bar 3}) 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. [CNRS, Pessac (France). Inst. de Chimie de la Matiere Condensee de Bordeaux; Derouet, J.; Beaury, L.; Porcher, P. [CNRS, Meudon (France). Lab. de Chemie Metallurgique et Spectroscopie des Terres Rares; El Bouari, A.; El Jazouli, A. [Faculte des Sciences Ben M`Sik, Casablanca (Morocco). Lab. de Chimie des Materiaux Solides

1999-03-01

50

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 R3 or the R32 space groups. The atomic arrangement is a three-dimensional framework formed by PO_4 tetrahedra sharing corners with TiO_6 octahedra. Co^2+ is located in half of the antiprism M(1) sites in a centered (R3) 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.; Flem, G. Le; Derouet, J.; Beaury, L.; Porcher, P.; Bouari, A. El; Jazouli, A. El

1999-03-01

51

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

52

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

International Nuclear Information System (INIS)

[en] 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.

2009-07-01

53

Characterization of protonically exchanged NASICON  

Energy Technology Data Exchange (ETDEWEB)

Instrumental Neutron Activation Analysis (INAA) was used to determine the amount of sodium present in NASICON powders (x=1.5) as a function of the extent of ion exchange in 0.2 molar HCl solutions. The INAA results showed not only that the conducting sodium was readily removed, but also that all the sodium (including structural) was removed. These results were quantitatively confirmed by ICP-AES analyses of the acid solutions used for the ion exchange. X-ray diffraction (XRD) studies of the NASICON powders showed that there were slight changes in their XRD patterns; the fully exchanged hydronium NASICON powder was found to be rhombohedral with slight but distinct changes in the hexagonal axis; the a axis was 2% smaller, but the c axis was 5% larger than for the precursor Na NASICON. The presence of an additional minor phase or phases in the fully exchanged samples was suggested. (orig.).

Komorowski, P.G.; Argyropoulos, S.A. (Dept. of Metallurgy and Materials Science, Univ. of Toronto, Ontario (Canada)); Hancock, R.G.V. (SLOWPOKE Reactor Facility and Dept. of Chemical Engineering and Applied Chemistry, Univ. of Toronto, Ontario (Canada)); Gulens, J. (AECL Research, Chalk River, Ontario (Canada)); Taylor, P. (AECL Research, Pinawa, Manitoba (Canada)); Canaday, J.D.; Kuriakose, A.K.; Wheat, T.A.; Ahmad, A. (Dept. of Energy Mines and Resources, CANMET, Ottawa, Ontario (Canada))

1991-11-01

54

New titanium-vanadium phosphates of NASICON and langbeinite structures, and differences between the two structures toward deintercalation of alkali metal  

Energy Technology Data Exchange (ETDEWEB)

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

Rangan, K.K.; Gopalakrishnan, J. (Indian Institute of Science, Bangalore (India))

1994-03-01

55

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

Science.gov (United States)

Mixed metal phosphates of the general formula Ax TiVIII(PO4)3, where A = Na, K, or Ba and (0 NASICON structure, the potassium compound, K2TiV(PO4)3, crystallizes with the langbeinite structure. BaTiV(PO4)3 is dimorphic, adopting the NASICON structure at lower temperatures and the langbeinite structure at higher temperatures. Ba1.5V2(PO4)3 and BaKV2(PO4)3, on the other hand, crystallize only with the langbeinite structure. Oxidative deintercalation of sodium from Na3TiV(PO4)3 readily occurs, yielding NaxTiV(PO4)3 (x ~ 1.0) and retaining the NASICON framework, while a similar deintercalation of potassium does not occur from the langbeinite K2TiV(PO4)3, revealing a difference in reactivity between the two structures: NASICON, being a skeleton structure with an interconnected interstitial space, facilitates mobility of alkali metal ions through the crystal, while langbeinite, being a true cage structure, does not permit a similar mobility.

Rangan, K. Kasthuri; Gopalakrishnan, J.

1994-03-01

56

?-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

2011-07-19

57

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

UK PubMed Central (United Kingdom)

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.

Kabbour H; Coillot D; Colmont M; Masquelier C; Mentré O

2011-08-01

58

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

59

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

International Nuclear Information System (INIS)

[en] 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

1982-05-14

60

Na4Fe2+Fe3+(PO4)3, 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+(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 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

2009-01-01

 
 
 
 
61

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.

Hatert, Frederic

2009-01-01

62

A mixed-valence niobium phosphate with an empty Nasicon structure: Nb/sub 2/(PO/sub 4/)/sub 3/  

Energy Technology Data Exchange (ETDEWEB)

Niobium(IV) niobium(V) phosphate, M/sub r/=470.73, trigonal, Ranti 3c, a=8.6974(7), c=22.123(2) A, V=1449.3(3) A/sup 3/, Z=6, D/sub x/=3.24 Mg m/sup -3/, /lambda/(Mo K/alpha/)=0.71073 A, /mu/=2.824 mm/sup -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 NbO/sub 6/ octahedra sharing corners with PO/sub 4/ tetrahedra and belongs to the empty Nasicon-type structure. (orig.).

Leclaire, A.; Borel, M.M.; Grandin, A.; Raveau, B.

1989-05-15

63

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

International Nuclear Information System (INIS)

[en] 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

1988-01-01

64

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

International Nuclear Information System (INIS)

[en] 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

2005-11-15

65

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

2008-04-24

66

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

UK PubMed Central (United Kingdom)

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.

Barré M; Crosnier-Lopez MP; Le Berre F; Bohnké O; Suard E; Fourquet JL

2008-06-01

67

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)

[en] 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[ru] ??????? ??????? ??????? ???? ??????????? ??????? Na1-xNi1-xCr1+x(MoO4)3 (0?x?0.4), ????????????????? ? ??????????? ???? ????????. ?? ?????? ???????????????????? ??????? ?????????? ???????????????????? ?????????, ?????????????????? ?? ? ?? ??????? ???? ??????????? ???????

2006-01-01

68

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

International Nuclear Information System (INIS)

[en] 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)

1988-01-01

69

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

70

Rare earth fluorescence in NASICON type phosphate glass, Na3TiZnP3O12  

International Nuclear Information System (INIS)

[en] 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)

1999-01-01

71

Li2NaV2(PO4)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

72

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

International Nuclear Information System (INIS)

[en] 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

1987-01-01

73

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

Energy Technology Data Exchange (ETDEWEB)

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.

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

1987-05-01

74

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

75

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)

[en] 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.)

1986-01-01

76

Phase transition in stoichiometric NASICON  

International Nuclear Information System (INIS)

[en] 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

1992-01-01

77

Chemical stability of Nasicon  

Energy Technology Data Exchange (ETDEWEB)

Nasicon solid electrolytes were tested by immersion in liquid sodium around 300/sup 0/C. The electrolytes were found to degrade due to chemical reaction with sodium. This reaction changes the lattice parameters of the electrolytes sufficiently to cause fracture. While the rapidity with which the degradation occurs depends on the electrolyte preparation method, the results indicate that a chemical stabilization of Nasicon towards sodium should be sought to make it a useful electrolyte.

Schmid, H.; DeJonghe, L.C.; Cameron, C.

1982-01-01

78

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)

[en] 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)

2010-01-01

79

Rhombohedral nasicon compound and battery  

Energy Technology Data Exchange (ETDEWEB)

Disclosed is a nasicon compound and a method of making it. The nasicon compound is rhombohedral at room temperture. The preferred compound is Na/sub 1//sub +/ /SUB x/ Zr/sub 2/Si /SUB x/ P/sub 3//sub -/ /SUB x/ O/sub 12/. A sodium sulfur battery using the nasicon compound is also disclosed.

Yoldas, B. E.; Lioyd, I. K.

1985-07-02

80

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

 
 
 
 
81

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

International Nuclear Information System (INIS)

[en] 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)

1996-07-15

82

Lithium mobility in the NASICON-type compound LiTi{sub 2}(PO{sub 4}){sub 3} by nuclear magnetic resonance and impedance spectroscopies  

Energy Technology Data Exchange (ETDEWEB)

Lithium mobility in LiTi{sub 2}(PO{sub 4}){sub 3} has been followed by {sup 7}Li NMR and impedance spectroscopies. From this analysis, three stages have been distinguished. (1) Below 230 K, lithium occupies preferentially the octahedral M{sub 1} sites of the NASICON structure. (2) Between 230 and 330 K, a low correlated and thermally activated lithium motion, with E{sub a} = 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 M{sub 2} sites is deduced from NMR data. (author)

Paris, Miguel A.; Martinez-Juarez, Ana; Rojo, Jose M.; Sanz, Jesus [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain)

1996-07-15

83

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

UK PubMed Central (United Kingdom)

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.

Yatskin MM; Strutynska NY; Baumer VN; Ogorodnyk IV; Slobodyanik NS

2012-07-01

84

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

85

Synthesis and Study of New Compounds (MI) (NIV)2(PO4)3 with Nasicon-like Structure (M = Ag, Cu; N = Ge, Hf, Sn, Ti, Zr)  

Science.gov (United States)

Compounds (MI) (NIV)2(PO4)3 (M = Ag, Cu; N = Ge, Hf, Sn, Ti, Zr) have been synthesized using solid-state reactions. Attempts to synthesize CuGe2(PO4)3 did not succeed. All other compounds have Nasicon-like structure (space group R3¯c ). AgGe2(PO4)3, AgHf2(PO4)3, CuSn2(PO4)3, and CuHf2(PO4)3 are described for the first time. Cell parameters, vibrational spectra, and ionic conductivities are given. Silver compounds have higher conductivities than, but the same spectral behavior as, corresponding sodium compounds. The spectra of copper compounds show significant differences, perhaps because of peculiar localization of copper in the structure.

Winand, J.-M.; Rulmont, A.; Tarte, P.

1993-12-01

86

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

International Nuclear Information System (INIS)

[en] 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

1989-01-01

87

Fast ion transport in the NASICON analog Na/sub 3/Sc/sub 2/(PO/sub 4/)/sub 3/: structure and conductivity  

Energy Technology Data Exchange (ETDEWEB)

The room temperature modification of stoichiometric NASICON(Sc) is monoclinic Cc. At 64 /sup 0/C there is a first order transition to a normal-conducting rhombohedral form R3c. Na(1) sites are fully occupied whereas Na(2) sites are partially occupied. At 167/sup 0/C there is a transition to a superionic phase, but the structure remains rhombohedral R3c. Vacancies are now shared equally by Na(1) and Na(2) sites. Fast Na-ion motion in stoichiometric Na/sub 3/Sc/sub 2/(PO/sub 4/)/sub 3/ arises from vacancy motion in a dogleg path between Na(1) and Na(2) sites. 15 references, 6 figures, 3 tables.

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

1983-12-01

88

Fast-ion transport in the NASICON analog Na/sub 3/Sc/sub 2/(PO/sub 4/)/sub 3/: structure and conductivity  

Energy Technology Data Exchange (ETDEWEB)

The room temperature modification of stoichiometric NASICON(Sc) is monoclinic Cc. At 64/sup 0/C there is a first order transition to a normal-conducting rhombohedral form R anti 3c. Na(1) sites are fully occupied whereas Na(2) sites are partially occupied. At 167/sup 0/C there is a transition to a superionic phase, but the structure remains rhombohedral R anti 3c. Vacancies are now shared equally by Na(1) and Na(2) sites. Fast Na-ion motion in stoichiometric Na/sub 3/Sc/sub 2/(PO/sub 4/)/sub 3/ arises from vacancy motion in a dogleg path between Na(1) and Na(2) sites.

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

1983-04-01

89

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

International Nuclear Information System (INIS)

[en] 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

2004-10-15

90

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

91

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 m...

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

92

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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...

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

93

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

94

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

UK PubMed Central (United Kingdom)

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.

Orlova AI; Volgutov VY; Castro GR; García-Granda S; Khainakov SA; García JR

2009-10-01

95

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

96

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

2012-06-23

97

Ionic conductivity and sinterability of NASICON-type ceramics: The systems NaM{sub 2} (PO{sub 4}){sub 3} + yNa{sub 2}O (M = Ge, Ti, Hf, and Zr)  

Energy Technology Data Exchange (ETDEWEB)

Sodium-rich NASICON-type ceramics, the NaM{sub 2}(PO{sub 4}){sub 3} + yNa{sub 2}O (M = Ge, Ti, Hf, Zr) systems, were investigated in order to obtain a material having a high Na{sup +} conductivity and high density. The ionic conductivity and the sinterability were greatly improved by an increase in the value of y for all of the systems examined. Added Na{sub 2}O was not soluble in the NASICON-type skeleton, since the lattice constants and the X-ray diffraction patterns were not changed by the Na{sub 2}O addition in all of the samples. Na{sub 2}O acts as a flux for obtaining highly dense ceramics and highly conductive grain boundaries. Partial A{sub 2} site insertion by Na{sup +} ions is effective for the enhancement of conductivity, because the conductivity for Na{sub 1.5}M(III){sub 0.5}Zr{sub 1.5}(PO{sub 4}){sub 3} (M = In or Y) is about 1 order of magnitude higher than the maximum conductivity of the NaZr{sub 2}(PO{sub 4}){sub 3} + yNa{sub 2}O system.

Aono, Hiromichi; Sugimoto, Eisuke [Niihama National Coll. of Technology, Niihama, Ehime (Japan). Dept. of Industrial Chemistry

1996-10-01

98

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

99

Ion conductivity of nasicon ceramics  

International Nuclear Information System (INIS)

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

1988-12-02

100

Production and characterization of Nasicon ceramics. Fremstilling og karakterisering af Nasicon-keramik  

Energy Technology Data Exchange (ETDEWEB)

The present work is a result of a number of government supported EFP-projects on manufacturing and characterization of sodium ion conducting ceramics based on the Nasicon solid solution, Na{sub 1+X}Zr{sub 2}Si{sub X}P{sub 3-X}O{sub 12}, ONasicon crystal structure is described and published cell parameters on the solid solution and substituted analogues are summarized in a model. The substitution Zr{sup 4+} <=> 4Na{sup +} is discussed. Phase equilibria in the plane described by the extended Nasicon formula, Na{sub 1+X+4Y}Zr{sub 2-Y}Si{sub X}P{sub 3-X}O{sub 12} showed a very limited substitution around the binary joint with Y>0.01. The liquid domain in the system Na{sub 2}O-ZrO{sub 2}-SiO{sub 2}P{sub 2}O{sub 5} at 1200 deg. C is estimated. Vlasovite is found to melt incongruently to Parakeldyshite + liquid below 1200 deg. C. Parakeldyshite is a solid solution given by the formula Na{sub 2-X}Zr{sub 2}Si{sub 2-X}P{sub X}O{sub 7}, 0Nasicon structure in the compositional range 2.1structure, nucleation of crystalline phases and sintering behaviour is outlined for the ZrO{sub 2} deficient composition, Na{sub 2.94}Zr{sub 1.49}Si{sub 2.20}P{sub 0.80}O{sub 10.85}. The ion conducti related to the texture of the ceramic. It is shown that resistivity is proportional to the total area of grain boundaries. The resistivity of the Nasicon crystal phase is estimated to 280 ohmcm at room temperature. Chemical durability in NaCl and NaOH is relatet to the glass phase in the ceramic. Electrolysis in NaOH/NaOH-cells at room temperature and 78 deg. C, shows that the results from the durability test applied for dynamic conditions. Na/Na-cells tests shows a complex interrelation between lifetime, current density and temperature. Temperature is the dominating factor. (author).

Weiland Hoej, J.

1988-07-01

 
 
 
 
101

Evaluation of the economical aspects of utilization of Nasicon in the chlor-alkali industry. Oekonomisk vurdering af anvendelsen af Nasicon i klor-alkali-industrien  

Energy Technology Data Exchange (ETDEWEB)

The economic aspects of the development of the product Nasicon for use in the chlor-alkali industry are investigated. Nasicon is a membrane based on polymers and the costs of substituting the Nasicon product for the currently used form of polymer based membranes are analysed. This involved the comparison of the technologies relevant to the production of the two types of membranes on the basis of a plant with a production capacity of 100.000 t C12 per year. Marginal costs of electricity consumption which is based on electrolyte resistance and where results are fairly uncertain because of the dependance on the amount of increase in the concentration of NaOH concentration, were calculated. The service life of Nasicon membranes were compared with that of those already in use and taken into consideration when working out sustitution costs. Expences in connection with changes in relevant parts of the plant are also taken into consideration. It was concluded that Nasicon is competative with other membranes because of the increased resistance to corrosion, and that Nasicon substitution should be conducive to energy conservation. In some areas the evaluation is subject to uncertainties. (AB) 15 refs.

Kjaer, J.

1987-12-15

102

High microwave susceptibility of NaH{sub 2}PO{sub 4}{sm_bullet}2H{sub 2}O: Rapid synthesis of crystalline and glassy phosphates with NASICON-type chemistry  

Energy Technology Data Exchange (ETDEWEB)

High microwave susceptibility of NaH{sub 2}PO{sub 4}{sm_bullet}2H{sub 2}O 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 {open_quotes}step-ladder{close_quotes} heating mechanism has been proposed to account for the high microwave absorbing ability of NaH{sub 2}PO{sub 4}{sm_bullet}2H{sub 2}O.

Vaidhyanathan, B.; Rao, K.J. [Indian Institute of Science, Bangalore (India)

1997-09-01

103

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

104

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

105

Non-polarisable dry electrode based on NASICON ceramic.  

UK PubMed Central (United Kingdom)

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.

Gondran C; Siebert E; Fabry P; Novakov E; Gumery PY

1995-05-01

106

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

107

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)

[en] 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

2008-02-05

108

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

109

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

International Nuclear Information System (INIS)

[en] 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

2007-01-01

110

Preparation and Characterization of NASICON Material by Sol-Gel Method  

UK PubMed Central (United Kingdom)

Solid electrolyte NASICON material has been synthesized by Sol-Gel method. The structure and composition were determined by XRD, IR absorption spectra, Raman spectra and NMR. The superionic electric characteristic was determined by conductivity measurement. The experimental results show that the powders sintered at 900 ? possess better properties compared with those of the samples sintered at 700, 800 and 1 100 ?.

Zhang Shuang; Quan Baofu; Zhao Zhiyong; Zou Yongcun; He Yuehua; Chen Lihua

2003-01-01

111

On the lattice defects in Nasicon compounds  

Energy Technology Data Exchange (ETDEWEB)

Samples of Nasicon compounds (Na super ionic conductor) with different silicon and phosphorus contents were investigated by performing radioluminescence experiments. In all samples examined, the Frenkel pairs, originated by the displacements of sodium ions in lacunar sites, were found to be the dominant defects. Some useful information on sodium ion mobility was obtained from the analysis of radioluminescence spectra.

Brovetto, P.; Maxia, V.; Salis, M. [Cagliari, Univ. (Italy). Ist. di Fisica Superiore - INFM-GNSM; Lucco-Borlera, M.; Mazza, D. [Turin, Politecnico (Italy). Dip. di Scienza dei Materiali e Ingegneria Chimica

1998-02-01

112

Computation of ionic conductivity at NASICON solid electrolyte (III) Na1 {yields}mid-Na{yields}Na2 conduction paths  

Energy Technology Data Exchange (ETDEWEB)

The ionic conductivity of NASICON (Na Super Ionic Conductor) solid electrolyte was simulated by using Monte Carlo Method (MCM) based on a hopping model. We assumed that the conduction path of Na ions is Na1{yields} mid-Na{yields}Na2, where the mid-Na sites are shallow potential sites to induce `a breathing-like movement` of Na ions in the NASICON framework. The minimum of charge correlation factor, f{sub c} and the maximum of appeared at nearby x=2.0. The occupancy of mid-Na site affected the depth of potential barrier and the conductivity of the NASICON. At above x=0.3, ln {sigma}T vs. 1/T{sup *} plots have been shown Arrhenius behavior but ln (VWf{sub c}) vs. 1/T{sup *} have been shown the Arrhenius type tendency at x=1. MCM results accorded with the experimental procedure. The role of mid-Na on Na{sup +} ion conduction could be explained by an additional driving force and a breathing-like movement model for motions of Na{sup +} ions in the NASICON framework. As we could not clearly remarked the model which is the better, it seems reasonable to conclude that these hypothesizes are suitable to explain the FIC behavior at NASICON. (author) 17 refs., 10 figs., 1 tab.

Choi, J.S. [Gyeongsang National University (Korea, Republic of) Dept. of Inorg. Mater. Eng.; Seo, Y.G. [Gyeongsang National University (Korea, Republic of) Dept. of Chemical Eng.; Kang, E.T. [Gyeongsang National University (Korea, Republic of) Dept. of Inorg. Mater. Eng.

1996-06-01

113

A New Nasicon-Type Phosphate:Co_0.5Ti_2(PO_4)_3 II. 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 g values) of the polycrystalline Co_0.5Ti_2(PO_4)_3 were simultaneously reproduced by use of a crystal field theory involving a set of F^k,zeta, free ion, and B^k_q crystal 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.; Flem, G. Le; Bouari, A. El; Jazouli, A. El

1999-03-01

114

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

115

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

UK PubMed Central (United Kingdom)

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

Antony CJ; Aatiq A; Panicker CY; Bushiri MJ; Varghese HT; Manojkumar TK

2011-01-01

116

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.

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

2012-01-01

117

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

Directory of Open Access Journals (Sweden)

Full Text Available 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.

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

2012-01-01

118

Nuclear quadrupole interaction measurements on 181Ta in NASICON  

International Nuclear Information System (INIS)

[en] 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.)

1983-01-01

119

Nuclear quadrupole interaction measurements on /sup 181/Ta in NASICON  

Energy Technology Data Exchange (ETDEWEB)

The quadrupole interaction experienced by the /sup 181/Ta nucleus placed in substitution for Zr in the Na/sub 3/Zr/sub 2/Si/sub 2/PO/sub 12/ compound (NASICON) has been determined from gamma-ray angular correlation experiments in the temperature range 20-700/sup 0/C. The asymmetry of the electric field-gradient tensor vanishes for T >approx. 200/sup 0/C, which is an indication for a non-random substitution of Si/sup 4 +/ for P/sup 5 +/ 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.

Baudry, A.; Boyer, P. (CEA Centre d' Etudes Nucleaires de Grenoble, 38 (France). Dept. de Recherche Fondamentale)

1983-12-01

120

23Na NMR studies of doped nasicon systems  

Science.gov (United States)

The positions of sodium ions in two doped nasicon systems were investigated by using 23Na solid state NMR techniques. The 23Na NMR spectra with a characteristic powder pattern of quadrupole interaction in the Na 1- XZr 2- XNb XP 3O 12 system indicated that sodium ions occupy Na(1) sites in the crystal structure. For the Na 1 + 2 XZr 2- XMg XP 3O 12 system, excepting the compound with X = 0.1, Gaussian lineshapes were observed due to the distribution of quadrupole parameters and the occupation of both Na(1) and Na(2) sites in the crystal structure. Two sodium sites can be distinguished by applying an inversion-recovery experiment.

Yue, Yong; Deng, Feng; Hu, Hongbin; Ye, Choahui

1995-03-01

 
 
 
 
121

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

UK PubMed Central (United Kingdom)

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.

Arbi K; París MA; Sanz J

2011-10-01

122

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

2011-09-06

123

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

Science.gov (United States)

The La1/3Zr2(PO4)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 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 (4.09×10-7 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

124

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

International Nuclear Information System (INIS)

[en] 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

2006-01-01

125

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 w...

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

126

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.; Marques, F. M. B.; Franco, J. I.

1999-01-01

127

Fremstilling og karakterisering af Nasicon-keramik. (Production and characterization of Nasicon ceramics).  

Science.gov (United States)

The present work is a result of a number of government supported EFP-projects on manufacturing and characterization of sodium ion conducting ceramics based on the Nasicon solid solution, Na(sub 1+X)Zr(sub 2)Si(sub X)P(sub 3-X)O(sub 12), ONasicon...

J. Weiland Hoej

1988-01-01

128

Oekonomisk vurdering af anvendelsen af Nasicon i klor-alkali-industrien. (Evaluation of the economical aspects of utilization of Nasicon in the chlor-alkali industry).  

Science.gov (United States)

The economic aspects of the development of the product Nasicon for use in the chlor-alkali industry are investigated. Nasicon is a membrane based on polymers and the costs of substituting the Nasicon product for the currently used form of polymer based me...

J. Kjaer

1987-01-01

129

Fabrication and sensing behavior of NASICON thick film SO{sub 2} gas sensor by screen-printing method  

Energy Technology Data Exchange (ETDEWEB)

The thick type sensor having Pt/Na super ionic conductor (NASICON) Pt/Na{sub 2}SO{sub 4}/Pt catalyst system for SO{sub 2} gas sensing was fabricated by screen printing method. The phases of NASICON with the variation of sintering temperature (1050 C, 1150 C, 1250 C) and sintering time (1.5 hr, 2.5 hr, 3.5 hr) were investigated by XRD. The variation of electromotive force of the sensor with SO{sub 2} concentration and operation temperature were also investigated. The major phase of NASICON film sintered at 1150 C for 3.5 hr was sodium zirconium silicon phosphate (Na{sub 3}Zr{sub 2}Si{sub 2}PO{sub 12}). The Nernest's slope of NASICON sensor for SO{sub 2} gas with the variation of concentration from 10 to 100 ppm was 176.12 mV/decade at the operating temperature of 500 C. The increase of oxygen partial pressure was not affected to the variation of Nernst's slope. (orig.)

Lee, S.T.; Bae, J.C.; Jun, H.K.; Huh, J.S. [Dept. of Materials Science and Metallurgy, Kyungpook National Univ., Daegu (Korea); Lee, D.D. [Dept. of Electronics, Kyungpook National Univ., Daegu, Korea, Daegu (Korea)

2003-07-01

130

Contact and Current Noise in Beta Alumina and Nasicon Ceramics.  

Science.gov (United States)

Experimental noise spectra of beta alumina and Nasicon ceramics in contact with Sodium Iodide propylene carbonate solution have been investigated. The noise of virgin contacts to both solid electrolytes decays exponentially with time. Low noise contacts c...

C. K. Kuo J. J. Brophy

1987-01-01

131

Humidity sensor using NASICON ceramic material. NASICON kei ceramic zairyo wo riyoshita shitsu sensor  

Energy Technology Data Exchange (ETDEWEB)

Many humidity sensors have been studied and developed, but at the present stage, they have troubles in their long term performance stability and accuracy, and have not reached the satisfactory level as yet. In this report, because of the above situation, a humidity sensor was experimentally fabricated using a thick film printing method and selecting highly ion conductive NASICON base ceramic material for the humidity sensor material. The obtained knowledge is as follows: Because of using NASICON material, the resistance on the low humidity side could be lowered and the measurement up to 10%RH could be realized. It was found that among NASICON materials, Na{sub 4}Zr{sub 2}Si{sub 3}O{sub 12} showed good linearity of the humidity sensitive property and was less prone to time lapse changes. Concerning the sensing mechanism, there was no change of sensing mechanism caused by any humidity increase. This was considered that tthe proton shift was the main cause thereof. Furthermore, since this sensor utilized the thick film printing method, its production was easy and the products which were good at mass productivity and reproductivity could be obtained. 5 refs., 9 figs., 2 tabs.

Yagi, H.; Saiki, T. (NGK Spark Plug Co. Ltd., Nagoya (Japan))

1991-09-25

132

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

Energy Technology Data Exchange (ETDEWEB)

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/O/sub 12/ (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.

Kreuer, K.D.; Kohler, H.; Warhus, U.; Schulz, H.

1986-02-01

133

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

International Nuclear Information System (INIS)

[en] 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

1986-01-01

134

Influence of thermal cycling on properties of NASICON  

Energy Technology Data Exchange (ETDEWEB)

Samples of NASICON were prepared from powders corresponding to the composition Nasub(1+x)Zr/sub 2/Sisub(x)Psub(3-x)O/sub 12/ with X = 2.0, 2.2, 2.32. The electric conductivity of the specimens was measured in the temperature range 20 to 400/sup 0/C using the complex admittance method. This method enabled us to derive the values of the bulk and the grain boundary. Since NASICON as a solid electrolyte is expected to find application in sodum sulfur batteries the influence of thermal cycling on its electric conductivity was investigated.

Bogusz, W.

1981-08-16

135

The effect of absorbed water on hydronium NASICON and Hyceram  

Energy Technology Data Exchange (ETDEWEB)

The bulk resistance of bonded hydronium NASICON, (Hyceram[sup TM]), was studied at 45 C in relative humidities ranging from 40% to 100% in both H[sub 2]O/N[sub 2] and D[sub 2]O/N[sub 2] atmospheres. The bulk resistance was found to increase exponentially with decreasing relative humidity. In addition, the isotope effect remained close to 2.2 over the range of relative humidities tested; therefore proton hopping (Grotthus mechanism) was shown to be the dominant conduction mechanism from saturation down to 40% relative humidity. Saturated and desiccated samples of hydronium NASiCON powder were prepared for X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The XRD patterns revealed that the change in the lattice plane spacings arising from the absorption of water was negligible. TGA showed that the x=1.5 form of hydronium NASICON contained at least 1.5 moles of absorbed water per mole of NASICON when saturated. In addition, the absorbed water was shown to be weakly held by the lattice since its evolution from the saturated sample was rapid. These XRD and TGA results suggested that the molecules of absorbed water occupy lattice sites which might afford considerable freedom of rotational and translational motion. (orig.)

Komorowski, P.G. (Toronto Univ., Ontario (Canada). Dept. of Metallurgy and Materials Science); Argyropoulos, S.A. (Toronto Univ., Ontario (Canada). Dept. of Metallurgy and Materials Science); Graydon, J. (Dept. of Chemical Engineering, Toronto Univ., Ontario (Canada)); Canaday, J.D. (Dept. of Energy Mines and Resources, CANMET, Ottawa, Ontario (Canada)); Kuriakose, A.K. (Dept. of Energy Mines and Resources, CANMET, Ottawa, Ontario (Canada)); Wheat, T.A. (Dept. of Energy Mines and Resources, CANMET, Ottawa, Ontario (Canada)); Ahmad, A. (Dept. of Energy Mines and Resources, CANMET, Ottawa, Ontario (Canada)); Taylor, P. (AECL Research, Pinawa, Manitoba (Canada))

1993-04-01

136

Study of defects in Nasicon compounds by thermoluminescence experiments  

Energy Technology Data Exchange (ETDEWEB)

Samples of Nasicon compounds with different silicon and phosphorus contents were investigated with spectrally resolved thermoluminescence. Evidence of the presence of charged point defects originated by exchange of silicon and phosphorus ions lying in different cells was obtained. Other defects are ascribed to displacements of sodium ions in unoccupied sites.

Lucco-Borlera, M.; Ronchetti, S. [Politecnico di Torino, Turin (Italy). Dipt. di Scienza dei Materiali e Ingegneria Chimica; Salis, M. [INFM-GNSM, Cagliari (Italy)]|[Cagliari, Univ. (Italy). Ist. di Fisica Superiore

1997-07-01

137

SO{sub 2} sensing characteristics of NASICON electrolytes  

Energy Technology Data Exchange (ETDEWEB)

SO{sub 2} gas in the global atmosphere is a main source of acid rain. There have been great efforts to find a good electrolyte of a galvanic cell for the continuous monitoring of sulphur dioxide emission gas. NASICON is a candidate as the sensor material, because of its high ionic conductivity even at low temperatures, little volume change upon thermal cycle, and unaltered physical properties when absorbed by water. Present work investigates the possibility of constructing and operating a NASICON cell with a Na{sub 2}SO{sub 4}-BaSO{sub 4} measuring electrode and a solid reference electrode of Na{sub 2}SiO{sub 3}.

Soon-Don Choi; Wan-Young Chung; Duk-Dong Lee [Yeungnam Univ., Kyongsan (Korea, Republic of)]|[Semyung Univ., Jechun (Korea, Republic of)]|[Kyungpook Univ., Taegu (Korea, Republic of)

1996-12-31

138

Protonic conductivity of Hyceram sup TM , a bonded hydronium NASICON  

Energy Technology Data Exchange (ETDEWEB)

The impedance method has been used to investigate the protonic conductivity of a bonded-hydronium NASICON electrolyte. Both the bulk and grain-boundary phases of the electrolyte are dramatically affected by the presence of water vapor in the hydrogen gas. The conductivity at 25degC exceeds that of many protonic materials and the material is stable to at least 200degC. Conductivity mechanisms are also discussed. (orig.).

Canaday, J.D.; Chehab, S.F.; Kuriakose, A.K.; Ahmad, A.; Wheat, T.A. (Ceramic Section, Dept. of Energy, Mines and Resources, CANMET, Ottawa, Ontario (Canada))

1991-10-01

139

Hydrogen electrolysis using a NASICON solid protonic conductor  

Energy Technology Data Exchange (ETDEWEB)

A protonic conductor based on a bonded NASICON disc has been used for hydrogen electrolysis at 300 K. Currents up to 200 mA can be passed through the disc, and the electrolysis proceeds with 100% current efficiency. The resistance of the ceramic is affected by its extent of hydration. Degradation and failure of the ceramic occurs at the cathode as a result of electrolysis.

Gulens, J.; Longhurst, T.H.; Kuriakose, A.K.; Canaday, J.D.

1988-09-01

140

A hydrogen sensor based on bonded hydronium NASICON  

Energy Technology Data Exchange (ETDEWEB)

A potentiometric hydrogen sensor which meets most of the gas-sensor criteria is discussed. The device consists of a bonded-hydronium-NASICON solid electrolyte and porous platinum electrodes. Electromotive-force, response-time and discharge measurements at 25deg C are presented, providing knowledge of both scientific and technological aspects of this device. The effects of water vapour on the sensor performance are also discussed. (orig.).

Chehab, S.F.; Canaday, J.D.; Kuriakose, A.K.; Wheat, T.A.; Ahmad, A. (Mineral Sciences Labs., CANMET, Energy Mines and Resources Canada, Ottawa, ON (Canada))

1991-04-01

 
 
 
 
141

Parsing with Typed Feature Structures  

CERN Multimedia

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

Wintner, S; Wintner, Shuly; Francez, Nissim

1996-01-01

142

Computer simulation of ionic conductivity in NASICON by using Monte Carlo Method  

Energy Technology Data Exchange (ETDEWEB)

From two dimension array, the ionic conductivity in Nasicon assessed a Monte Carlo Method. The maximum conductivity on MCM results ranges from 0.7 to 0.8 and this trends agreed with experimental works of ionic conductivity in Nasicon. (orig.)

Choi, J.S. [Dept. of Inorganic Materials Eng., Gyeongsang National Univ. (Korea, Republic of); Seo, Y.G. [Dept. of Inorganic Materials Eng., Gyeongsang National Univ. (Korea, Republic of)]|[Dept. of Chemical Engineering, Gyeongsang National Univ., Seoul (Korea, Republic of); Kang, E.T. [Dept. of Inorganic Materials Eng., Gyeongsang National Univ. (Korea, Republic of)

1995-04-01

143

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

UK PubMed Central (United Kingdom)

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.

Mauvy F; Siebert E; Fabry P

1999-02-01

144

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

145

Nasicon-like copper(II) titanium phosphate Cu/sub 0. 50/Ti/sub 2/(PO/sub 4/)/sub 3/  

Energy Technology Data Exchange (ETDEWEB)

Cu/sub 0.50/Ti/sub 2/(PO/sub 4/)/sub 3/ is a Nasicon-type phase with a cooperative Jahn-Teller distortion below 550/sup 0/C. Crystal field, electron paramagnetic resonance, and magnetic data seem to be consistent with an octahedral surrounding and a d/sub x/sup 2/-y/sup 2///sup 1/ ground state of Cu/sup 2 +/.

Jazouli, A.E.; Soubeyroux, J.L.; Dance, J.M.; Le Flem, G.

1986-12-01

146

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

UK PubMed Central (United Kingdom)

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.

Roy S; Kumar PP

2013-04-01

147

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

148

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 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 (more) 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 interio (more) r 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.

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

1997-06-01

149

Síntesis mediante química sol gel de compuestos Li1+xMiiixTi2-x(PO4)3 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(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.Haciendo uso de la química sol-gel, se han preparado ortofosfatos de composición LiTi2(PO4)3 y Li1.05(Cr/Fe)0.05Ti1.95(PO4)3 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.

Pérez-Estébanez, M.; Rivera-Calzada, A.; León, C.; Santamaría, J.; Isasi-Marín, J.

2010-01-01

150

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

151

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.; Lamas, D. G.; Fernández de Rapp, M. E.; Figueiredo, F. M.; Frade, J. R.; Marques, F. M. B.; Franco, J. I.

2004-01-01

152

Study of defects in Zr lacunar Nasicon crystals  

International Nuclear Information System (INIS)

[en] 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

1998-01-01

153

Study of defects in Zr lacunar Nasicon crystals  

Energy Technology Data Exchange (ETDEWEB)

Samples of Nasicon compounds Na{sub x}Zr{sub 2-y}Si{sub 3-z}P{sub z}O{sub 12}, 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{sup +} ions exceed 5 A. This results yields information on the paths of Na{sup +} ions in the ionic conduction of these materials.

Brovetto, P.; Maxia, V.; Salis, M. [Univ. Cagliari (Italy). INFM-GNSM, Ist. di Fisica Superiore; Lucco-Borlera, M.; Mazza, D. [Politecnico, Turin (Italy). Dip. di Scienza dei Materiali e Ingegneria Chimica

1998-06-01

154

Influence of thermal cycling on properties of NASICON  

International Nuclear Information System (INIS)

[en] 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

1981-08-16

155

Nasicon solid electrolytes. Part II: X-ray diffraction experiments on sodium-zirconium-phosphate single crystals at 295K and at 993K  

Energy Technology Data Exchange (ETDEWEB)

The structure of an end member (x=0) of the NASICON solid solution system Na/sub 1//sub+/subX/sub+/sub-/subYZr/sub 2//sub-/subYSi/subXP/sub 3//sub-/subXO/sub 12/, 0 less than or equal to x less than or equal to 3, 0 less than or equal to y less than or equal to 1 was investigated at room temperature and at 993K. The authors present a model which prompts that both effects are correlated. The occupancy of the Na2 site - not significant at room temperature - was refined to about 10% at 993K. The results from both measurements can be correlated only, if at room temperature Na/sup +/ is located in the interstitial sites and if the transition of these ions to the Na2 site occurs at high temperature. Additional refinement of higher order temperature coefficients of the Na sites at 993K yielded a Na diffusion path Na1-Na2 similar to that found in other NASICON compositions. The height of the effective one particle potential barrier agrees quite well with the activation enthalpy measured on single crystals with impedance methods. Therefore they conclude that in this NASICON composition the main diffusion they process is a bulk process.

Kohler, H.; Schulz, H.

1986-01-01

156

Effect of Decomposition on the Densification and Properties of NASICON Ceramic Electrolytes.  

Science.gov (United States)

Processing and characterization of NASICON ceramic electrolytes have been conducted using a number of different techniques. Sintering of these materials was accomplished at temperatures between 1100 exp 0 C and 1375 exp 0 C. Results of this work have show...

B. J. McEntire R. A. Bartlett G. R. Miller R. S. Gordon

1982-01-01

157

Fabrication and Characterization of NASICON Ceramic Electrolytes. Monthly Technical Progress Report, February 1--February 28, 1979.  

Science.gov (United States)

Additional samples of NASICON formed from mechanically mixed powders were formed and sintered to adequate mass density. For such mechanical mixtures, sintered densities were determined as a function of sintering temperature and time. In these studies, par...

R. S. Gordon

1979-01-01

158

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

Energy Technology Data Exchange (ETDEWEB)

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/O/sub 12/. This sample, prepared by reheating a commercially available NASICON to minimize the ZrO/sub 2/ impurity, has been previously structurally refined from room temperature neutron diffraction data collected at Argonne National Laboratory. Conductivity measurements show a cusp at ca. 170/sup 0/C attributed to the monoclinic-rhombohedral transition and the purpose of this work was to explore the nature of the transition. Data runs were made at 143, 173, 202, 300, and 391/sup 0/C. No evidence for a crystal system change was found. The highest temperature data sets could not be refined satisfactorily by the Rietveld method using a rhombohedral model, but rather required a monoclinic cell in space group C2/c to achieve convergence. An explanation for the conductivity cusp is given in terms of disordering of the sodium ions and a change in conduction pathways which lowers the barriers to ion movement.

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

1988-01-01

159

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

International Nuclear Information System (INIS)

[en] 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

1988-01-01

160

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

 
 
 
 
161

Doppler broadened and ionic conductivity studies on NASICON analogue  

Energy Technology Data Exchange (ETDEWEB)

Doppler broadened lineshape and ionic conductivity measurements have been made in the NASICON analogue Na{sub 2}(La,Al)Zr(PO{sub 4}){sub 3} synthesized with four different concentrations of ZrO{sub 2} (2, 2.2, 2.8 and 5.2 by wt.%) in the nutrient at room temperature. The lineshape parameter S is calculated for each concentration and it shows maximum value and the a.c. ionic conductivity {sigma} shows minimum value for the material with 2.8 (wt.%) concentration of ZrO{sub 2} in the nutrient. An attempt has been made in correlating the changes in S parameter with {sigma}. The results show that the defect density is maximum for the material with 2.8 (wt.%) concentration of ZrO{sub 2} for which the conduction paths of Na{sup +} ion are restricted. (orig.).

Ravindrachary, V.; Sreeramalu, V.; Sreepad, H.R.; Chandrashekara, A.; Gopal, S. (Dept. of Studies in Physics, Univ. of Mysore, Manasagangotri (India))

1991-10-01

162

Positron annihilation studies on nasicon analogues containing cation vacancies  

International Nuclear Information System (INIS)

[en] 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

1990-01-01

163

Abstract Machine for Typed Feature Structures  

CERN Multimedia

This paper describes a first step towards the definition of an abstract machine for linguistic formalisms that are based on typed feature structures, such as HPSG. The core design of the abstract machine is given in detail, including the compilation process from a high-level specification language to the abstract machine language and the implementation of the abstract instructions. We thus apply methods that were proved useful in computer science to the study of natural languages: a grammar specified using the formalism is endowed with an operational semantics. Currently, our machine supports the unification of simple feature structures, unification of sequences of such structures, cyclic structures and disjunction.

Wintner, S; Wintner, Shuly; Francez, Nissim

1994-01-01

164

Abstract Machine for Typed Feature Structures  

CERN Multimedia

This paper describes an abstract machine for linguistic formalisms that are based on typed feature structures, such as HPSG. The core design of the abstract machine is given in detail, including the compilation process from a high-level language to the abstract machine language and the implementation of the abstract instructions. The machine's engine supports the unification of typed, possibly cyclic, feature structures. A separate module deals with control structures and instructions to accommodate parsing for phrase structure grammars. We treat the linguistic formalism as a high-level declarative programming language, applying methods that were proved useful in computer science to the study of natural languages: a grammar specified using the formalism is endowed with an operational semantics.

Wintner, S; Wintner, Shuly; Francez, Nissim

1995-01-01

165

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

166

Microstructure-conductivity relations in superconducting composite ceramics (Nasicon)/insulating glass  

Energy Technology Data Exchange (ETDEWEB)

NASICON (Na/sub 3/Zr/sub 2/Si/sub 2/PO/sub 12/)/low conductor (Na/sub 2/Zr/sub 4/Si/sub 16/P/sub 8/O/sub 61/ glass) composites ceramics have been synthesized using sol-gel process and low-temperatures sintering. The microstructures have been studied by scanning electron microscopy and the chemical reaction between NASICON grains and the intergranular glassy second phase has been analysed using Raman Microprobe spectroscopy. Conductivity has been measured by impedance spectroscopy for various glass content between 3 and 90% (by weight) and for various degrees of reactions between NASICON and glass. The percolation threshold is about 5% and up to 10% the properties are similar to those of the low conducting phase. A conductivity anomaly is observed for 3% glass content.

Colomban, P.

1987-08-01

167

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

Energy Technology Data Exchange (ETDEWEB)

Processing and characterization of NASICON ceramic electrolytes have been conducted using a number of different techniques. Sintering of these materials was accomplished at temperatures between 1100/sup 0/C and 1375/sup 0/C. Results of this work have shown that NASICON ceramics with compositions around x=2 (i.e., Na/sub 3/Zr/sub 2/Si/sub 2/Po/sub 12/), are not monophase, possess poor mechanical strength and an anomalous thermal expansion behavior, and are subject to chemical instability in the presence of liquid sodium (at 300/sup 0/C). Using wet-chemical techniques, x-ray diffraction analysis, and SEM observations, it was found that NASICON apparently exhibits phase and chemical decomposition at densification temperatures. The products of this decomposition process can be correlated with the poor physical and corrosion-resistant properties.

McEntire, B.J.; Bartlett, R.A.; Miller, G.R.; Gordon, R.S.

1982-03-01

168

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

International Nuclear Information System (INIS)

[en] 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

1983-01-01

169

The study of hydronium NASICON conductivity with deuterium  

International Nuclear Information System (INIS)

[en] 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

1992-01-01

170

[Types, structure, and function of scientific articles].  

UK PubMed Central (United Kingdom)

OBJECTIVE: To define the importance of the scientific article as a source of original information. METHODS: To describe the fundamental contents of the scientific article and its three different formats: original scientific article, review article and case reports. CONCLUSIONS: The contents and structure of the different documents vary depending on the type of article considered as a result of the goal pursued with its publication.

Garrido Díaz I; López Rodríguez L; Seda Diestro J; Aparcero Bernet L; Chacartegui Martínez I

2002-10-01

171

Structural and vibrational studies of NaZr2(AsO4)3  

International Nuclear Information System (INIS)

[en] 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

2003-10-30

172

Structure and thermal expansion of LiGe sub 2 (PO sub 4 ) sub 3  

Energy Technology Data Exchange (ETDEWEB)

LiGe{sub 2}(PO{sub 4}){sub 3} belongs to the Nasicon-type family. Room-temperature structure has been determined on a single crystal from 3D X-ray data. Thermal evolution of this structure has been established from neutron powder diffraction data between 300 and 1,000 K using the Rietveld method. The thermal expansion is positive along the c-axis, whereas shrinking is observed along the a-axis below 900 K, followed by dilatation. The atomic displacements noted with increasing temperature are consistent with a model proposed for NaZr{sub 2}(PO{sub 4}){sub 3}.

Alami, M.; Brochu, R. (Departement de Chimie de la Faculte des Sciences de l' Universite Mohamed V, Rabat (Morocco)); Soubeyroux, J.L. (Institut Lauee-Langevin, Grenoble (France)); Gravereau, P.; Le Flem, G.; Hagenmuller, P. (Laboratoire de Chimie du Solide du CNRS, Talence (France))

1991-02-01

173

Tin clathrates with the type II structure.  

UK PubMed Central (United Kingdom)

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

Schäfer MC; Bobev S

2013-02-01

174

Term Encoding of Typed Feature Structures  

CERN Document Server

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 further specification of feature-value declarations on subtypes. In the present approach, these spececial cases can be handled as well, though with some increase in complexity. For grammars without multiple inheritance and specification of feature values, the encoding presented here reduces to that of previous approaches. From no-reply@xxx.lanl.gov Thu Nov 4 08:42 MET 1999 Received: from newmint.cern.ch (newmint.cern.ch [137.138.26.94]) by sundh98.cern.ch (8.8.5/8.8.5) with ESMTP id IAA19170 for ; Thu, 4 Nov 1999 08:42:29 +0100 (MET) Received: ...

Gerdemann, D

1995-01-01

175

Types of provincial structure and population health.  

UK PubMed Central (United Kingdom)

This paper explores the potential of using large administrative units for studies of population health within a country. The objective is to illustrate a new way of defining structural dimensions and to use them in examining variation in life expectancy rates. We use data from the 50 provinces of Spain as a case study. A factor analysis of organizational items such as schools, hotels and medical personnel is employed to define and generate "collective" measures for well-known provincial types, in this case: urban, commercial, industrial and tourist provinces. The scores derived from the factor analysis are then used in a regression model to predict life expectancy. The City-centered and Commercial provinces showed positive correlations with life expectancy while those for the Tourist provinces were negative. The industrial type was nonsignificant. Explanations of these correlations are proposed and the advantages and disadvantages of this exploratory technique are reviewed. The use of this technique for generating an overview of social organization and population health is discussed.

Young FW; Rodriguez E

2005-01-01

176

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

Science.gov (United States)

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

Li, Yingjeng James

177

A Mixed ?/? Superstructure in NASICON Ionic Conductors: Neutron Diffraction Study of Li2FeTi(PO4)3 and Li2FeZr(PO4)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 1 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

178

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

Energy Technology Data Exchange (ETDEWEB)

Nasicon ceramic electrolytes were processed and characterized using a number of different techniques. The materials were sintered at T = 1100/sup 0/C to 1375/sup 0/C. Results of this work demonstrate that Nasicon ceramics with compositions around x = 2 (i.e. Na/sub 3/Zr/sub 2/Si/sub 2/PO/sub 12/), 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.

McEntire, B.J.; Bartlett, R.A.; Gordon, R.S.; Miller, G.R.

1983-10-01

179

Recycling Caustic from LAW Stream using NaSICON Membrane based Electrochemical Technology  

International Nuclear Information System (INIS)

[en] 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)

2009-01-01

180

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

International Nuclear Information System (INIS)

[en] 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

2004-07-15

 
 
 
 
181

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

182

Fabrication and Sensing Properties of NASICON Thick Film SO{sub 2} Gas Sensor Using Screen-print Method  

Energy Technology Data Exchange (ETDEWEB)

The thick film type sensor having Pt/Na Super Ionic CONductor(NASICON) solid electrolyte/Pt/Na{sub 2}SO{sub 4}/Pt catalyst system for SO{sub 2} gas was fabricated by screen-print method. The phase of Na Super Ionic Conductor solid electrolyte sintered at different temperature of 1050, 1150, 1250 deg. C and for different time of 1.5, 2.5, 3.5 hr were investigated by XRD. The Electromotive Force variation of the sensor with SO{sub 2} concentrations and operating temperatures were investigated. The major phase of Na Super Ionic Conductor film sintered at 1150 deg. C for 3.5 hr was sodium zirconium silicon phosphate (Na{sub 3}Zr{sub 2}Si{sub 2}PO{sub 12}). The Nernst's slope of Na Super Ionic Conductor sensor for SO{sub 2} gas with the variation of concentration from 10 to 100 ppm was 167.14 mV/decade at the operating temperature of 500 deg. C. The increase of oxygen partial pressure was not affected to the variation of Nernst's slope. (author). 15 refs., 7 figs.

Bae, J.C.; Lee, S.T.; Jun, H.K.; Bang, Y.I.; Lee, D.D.; Huh, J.S. [Kyungpook National University, Taegu (Korea)

2003-02-01

183

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

International Nuclear Information System (INIS)

[en] 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

1995-01-01

184

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

185

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

Energy Technology Data Exchange (ETDEWEB)

Using the galvanic cell: Pt vertical bar Au,CO{sub 2},O{sub 2} vertical bar a{sub Na{sup '}{sup '}{sup '}} Na{sub 2}CO{sub 3}(Au) vertical bar a{sub Na}{sup '}'NASICON vertical bar a{sub Na}'FeO+NiO{sub (borateglass)}|FeNi(48)|Au |Pt the p-electronic conduction parameter a{sub -}bar of NASICON was characterized as a function of the sodium activity a{sub Na}{sup '}' and the temperature. For that purpose, the isothermal voltage response to successive variations of a{sub Na}{sup '}' by changing the composition of the CO{sub 2}-O{sub 2} gas mixture was evaluated by a non-linear regression procedure. Within the temperature range under investigation (300-620 deg. C) it holds that: loga{sub +} =11.076+/-0.1-(18278.0+/-1100)KT(T=<500 deg. C) loga{sub +}=-3.519+/-1.7-(7904+/-1400)KT(500 deg. C=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.

Shqau, K.; Naefe, H.; Aldinger, F.; Figueiredo, F.M

2004-07-15

186

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

187

Ceramic materials on perovskite-type structure for electronic applications  

International Nuclear Information System (INIS)

Ceramic materials exhibiting the perovskite-type structure constitute among others, resource base for many fields of widely understood electronics (i.e., piezoelectronics, accustoelectronics, optoelectronics, computer science, tele- and radioelectronics etc.). Most often they are used for fabrication of different type sensors (detectors), transducers, ferroelectric memories, limiters of the electronic current intensity, etc., and hence they are numbered among so-called intelligent materials. Prototype structure of this group of materials is the structure of the mineral called perovskite (CaTiO3). By means of right choice of the chemical composition of ABO3 and deforming the regular perovskite structure (m3m) more than 5000 different chemical compounds and solid solutions exhibiting the perovskite-type structure have been fabricated. The concept of perovskite functional ceramics among often things ferroelectric ceramics, pyroelectric ceramics, piezoelectric ceramics, electrostrictive ceramics, posistor ceramics, superconductive ceramics and ferromagnetic ceramics. New possibilities of application of the perovskite-type ceramics are opened by nanotechnology. (author)

2003-01-01

188

SO2-sensing characteristics of NASICON sensors with ZnSnO3 sensing electrode  

International Nuclear Information System (INIS)

[en] 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

2008-06-25

189

Final report on evaluation of CANMET Nasicon ceramics in sodium/sodium cells  

Energy Technology Data Exchange (ETDEWEB)

Nine samples of Nasicon discs were forwarded to the Ceramic Engineering Research Group at McMaster University for testing in sodium-sodium cells. The surfaces of each disc were prepared by grinding to a parallel surface on a diamond wheel, grinding on a rotating wheel using a number600 grade wet emery paper (methanol being used), and mechanically polishing using diamond paste down to 1..mu..m. The final mean thicknesses and diameters of the discs were recorded. X-ray diffraction was carried out on randomly selected discs and showed the materials to be crystalline. The a.c. impedance of each Nasicon disc was measured as a function of temperature. Once the electrical impedance had been measured, the electrolytes were characterised in sodium-sodium cells. The filling with sodium was carried out in an atmosphere of ultra-high purity argon to prevent aerial oxidation of the sodium. Experimental data are presented to evaluate the degradation of each electrolyte. 13 figs.

Nicholson, P.S.; Munshi, M.Z.A.

1983-11-01

190

Hydroelastic responses of pontoon type very large floating offshore structure  

Energy Technology Data Exchange (ETDEWEB)

The authors developed the estimating method of the hydroelastic response of a very large pontoon type floating structure. In this method, the pressure distribution method with shallow draft assumption was used to obtain the hydrodynamic forces considering the elastic motion of a floating body. The elastic responses of very large floating structure were estimated by using 1-D beam modeling. On the other hand, to observe the elastic response of a large pontoon type structure they carried out experiments in head sea and head-beam sea conditions. The experimental model was an elastic model of pontoon type large floating body. To validate numerical estimation method the authors compared the numerical results with experimental results. From these results, they found good agreement and confirmed the accuracy of this numerical estimation method of the hydroelasticity of a very large pontoon type floating structure.

Haeda, Hisaaki; Miyajima, Shyogo [Univ. of Tokyo (Japan). Inst. of Industrial Science; Masuda, Koich; Ikoma, Tomoki [Nihon Univ., Funabashi, Chiba (Japan)

1996-12-31

191

Factor structure of English-language personality type-nouns.  

UK PubMed Central (United Kingdom)

Although type-nouns (e.g., idiot, hero) are important in person description, lexical studies of personality have concentrated on adjectives. This study tested structural hypotheses using 372 highly familiar English-language type-nouns and descriptions by 607 participants of either themselves, a liked, or a disliked target person. One- and 2-factor structures were most robust, and replicated similar structures found in previous adjectival studies. Additionally, the structure with 8 orthogonal factors had good replicability and applicability within single-gender subsamples; as in previous studies of type-nouns, it included factors corresponding directly to Extraversion and Intellect/Openness, but also to Attractiveness and Masculinity (or Ruggedness). The Big Five was only weakly replicated. Personality taxonomies based on adjectives are unlikely to be comprehensive, because type-nouns have different content emphases.

Saucier G

2003-10-01

192

Stochastic Fatigue Analysis of Jacket Type Offshore Structures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Sigurdsson, Gudfinnur

193

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

1991-01-01

194

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

195

The Structure of Na5Ti(PO4)3  

Science.gov (United States)

The sodium titanium phosphate Na5Ti(PO4)3 crystallizes in the trigonal space group R32 (a = 9.0607(2) Å, c = 21.734(1) Å, V = 1545.3 Å3, dm = 2.84(2), dc = 2.89 Mg . m-3, Z = 6). R = 0.022 and Rw = 0.023 for 831 reflections. The structure belongs to the Nasicon-type family and is characterized by a 2-2 titanium-sodium ordering along the c axis. The four crystallographically independent sodium atoms show coordination numbers 6 and 8. The cell parameters and the cationic distribution are consistent with the rules governing the structural evolution of such types of material.

Krimi, S.; Mansouri, I.; El Jazouli, A.; Chaminade, J. P.; Gravereau, P.; Le Flem, G.

1993-08-01

196

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

UK PubMed Central (United Kingdom)

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.

Gondran C; Siebert E; Yacoub S; Novakov E

1996-11-01

197

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

198

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

199

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

International Nuclear Information System (INIS)

[en] 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

2009-01-01

200

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

International Nuclear Information System (INIS)

[en] 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)

2004-01-01

 
 
 
 
201

Wetting characteristics of sodium on. beta. ''-alumina and on nasicon  

Energy Technology Data Exchange (ETDEWEB)

The sessile drop technique was used to determine the wetting characteristics of liquid sodium on ..beta..''-alumina and nasicon (Na/sub 3/Zr/sub 2/Si/sub 2/PO/sub 1//sup 2/). The effects of moisture and temperature were studied using the wetting experiments. A range of contact angles (from 0 to 160/sup 0/) were observed. The samples exposed to moisture exhibited poor wetting. The fact that good wetting is a prerequisite for improved cell performance was demonstrated via Na absolute value..beta..''-alumina Na cell tests. Cells baked out in a vacuum passed in excess of 1 100 A h cm/sup -2/ at 4 A cm/sup -2/ current density without any degradation. Unbaked cells under similar conditions failed under 200 A h cm/sup -2/.

Viswanathan, L.; Virkar, A.V.

1982-01-01

202

Co-linear spin configurations in corundum-type structures  

International Nuclear Information System (INIS)

[en] 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)[fr] Les configurations magnetiques colineaires, possibles dans les structures du type corindon (Fe2O3-?; Cr2O3), sont solutions d'un probleme matriciel. Leurs domaines de stabilite sont delimites par des relations d'inegalite entre integrales d'echange. (auteur)

1961-01-01

203

Modulation mechanism and disorder structure in hollandite-type crystals  

International Nuclear Information System (INIS)

The structural modulation in some hollandite-type crystals is explained by a vacancy-displacive modulation model. In this model the large cations located in the tetragonal channels along the c axis deviate from the average position to form a modulation wave. Three types of disorder in the initial phase of the modulation wave have been introduced to interpret apparently different diffraction patterns in hollandite-type crystals. A mathematical analysis as well as optical diffraction give results similar to those experimentally observed. High-resolution transmission electron microscope images have been observed to confirm the discussion further. (orig.)

1991-07-01

204

Modulation mechanism and disorder structure in hollandite-type crystals  

Energy Technology Data Exchange (ETDEWEB)

The structural modulation in some hollandite-type crystals is explained by a vacancy-displacive modulation model. In this model the large cations located in the tetragonal channels along the c axis deviate from the average position to form a modulation wave. Three types of disorder in the initial phase of the modulation wave have been introduced to interpret apparently different diffraction patterns in hollandite-type crystals. A mathematical analysis as well as optical diffraction give results similar to those experimentally observed. High-resolution transmission electron microscope images have been observed to confirm the discussion further. (orig.).

Wu Xiaojing; Fujiki, Yoshiki; Horiuchi, Shigeo (National Inst. for Research in Inorganic Materials, Ibaraki (Japan)); Ishigame, Mareo (Research Inst. for Scientific Measurements, Tohoku Univ., Sendai (Japan))

1991-07-01

205

Prediction of Type A behaviour: a structural equation model  

Scientific Electronic Library Online (English)

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

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

2009-01-01

206

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

207

Star cell type core configuration for structural sandwich materials  

Energy Technology Data Exchange (ETDEWEB)

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

Christensen, Richard M. (Danville, CA)

1995-01-01

208

New types of localized structures in laser radiation  

Energy Technology Data Exchange (ETDEWEB)

New types of stable transversely two-dimensional localized radiation structures are found in a wide-aperture laser with saturable absorption with the axisymmetric intensity distribution and wave-front dislocation of the highest order and with the rotating nonaxisymmetric intensity distribution. 4 refs., 3 figs.

Rozanov, N.N.; Fedorov, A.V.; Fedorov, S.V.; Khodova, G.V. [Vavilov State Optical Institute, St. Petersburg (Russian Federation)

1995-11-01

209

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

International Nuclear Information System (INIS)

[en] 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[ru] ? ????? ???????? ???????????? ????? ???????? ???????? (M = Li-Cs) ? ?????????? ?????? (4, 5) ??????? Nb2(PO4)3 (1) ?????????? ????? ??????? ???????????? ???? MxNb1+x4+Nb1-x5+ (PO4)3 (2) ??????? 1 ?? ???????? ?????? ???????????????? ????????? ??????. ?????????? ?????????? ???????????????? ??????? ???????????, ???????????? ? ??????????????? ????????, ? ????? ??-?????????????. ???????????, ??? ??? ??????? 1, ??? ? ???? ??? ??????? ????????? ????????? 2 ??????????? ? ???????????? ???? NASICON. ???????? ????????? ??????? ?????????? ?? ??? ??????? ? ???????????? ??????????? ???????????? ???????????? ??????? ????????? ?????? (4) ? ???????????? ?????????? ???????????? 2 ?????????????? ???????

2001-01-01

210

Prediction of type A behaviour: A structural equation model  

Directory of Open Access Journals (Sweden)

Full Text Available The predictability of Type A behaviour was measured in a sample of 375 professionals with a shortened version of the Jenkins Activity Survey (JAS). Two structural equation models were constructed with the Type A behaviour achievement sub-scale and global (total) Type A as the predictor variables. The indices showed a reasonable-to-promising fit with the data. Type A achievement was reasonably predicted by service-career orientation, internal locus of control, power self-concept and economic innovation. Type A global was also predicted by internal locus of control, power self-concept and the entrepreneurial attitude of achievement and personal control.How to cite this article:Van Wyk, R., Boshoff, A.B., Nieman, G., Van Vuuren, J., & Pretorius, M. (2009). Prediction of type A behaviour: A structural equation model. SA Journal of Industrial Psychology/SA Tydskrif vir Bedryfsielkunde, 35(1), Art. #758, 9 pages. DOI: 10.4102/sajip.v35i1.758

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

2009-01-01

211

Harmonic structure of type IIIb and III bursts  

International Nuclear Information System (INIS)

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

1979-01-01

212

Crystal growth conditions and structural features of ladder type superconductors  

International Nuclear Information System (INIS)

The single crystals (M2Cu2O3)m(CuO2)n (M = Ca, Sr, Y, Bi) containing the ladder-type plane Cu2O3 were obtained by the flux method using Bi- and Ba-cuprates as fluxes. The single crystals with m/n-values 5/7 and 1/1 were found to be superconducting (SC) with the onset of the transition at 80 K. The regularities of the SC crystals with the ladder-type structure were discussed from the viewpoint of the crystal chemistry.

1999-08-02

213

Crystal growth conditions and structural features of ladder type superconductors  

Energy Technology Data Exchange (ETDEWEB)

The single crystals (M{sub 2}Cu{sub 2}O{sub 3}){sub m}(CuO{sub 2}){sub n} (M = Ca, Sr, Y, Bi) containing the ladder-type plane Cu{sub 2}O{sub 3} were obtained by the flux method using Bi- and Ba-cuprates as fluxes. The single crystals with m/n-values 5/7 and 1/1 were found to be superconducting (SC) with the onset of the transition at 80 K. The regularities of the SC crystals with the ladder-type structure were discussed from the viewpoint of the crystal chemistry.

Leonyuk, L.; Szymczak, R.; Szymczak, H.; Baran, M.; Babonas, G.J.; Maltsev, V.; Shvanskaya, L.; Reza, A.

1999-12-01

214

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

2001-01-01

215

Notes on SU(3) structures in type IIB supergravity  

International Nuclear Information System (INIS)

We study solutions of type IIB supergravity with an SU(3) structure group and four dimensional Poincare invariance and present relations among the bosonic fields which follow from the supersymmetry variations. We make explicit some results which also follow from the more general case of an SU(2) structure and give some short comments applicable to general supersymmetric solutions. We also provide simplified relations appropriate for duals of gauge theory renormalization group flows, and use these to derive the supergravity solution for a bound state of (p,q)5-branes and D3-branes. (author)

2004-01-01

216

Synthesis and Conductivities of Sulfate/Selenate Phases Related to Nasicon: NaxM'(II)xM''(III)2-x(SO4)3-y(SeO4)y  

Science.gov (United States)

The synthesis of Na containing Nasicon-type phases of the form NaxM'(II)xM''(III)2-x(SO4)3-y(SeO4)y (M' = Mg, Zn, Cd, Mn; M'' = Al, Cr, Fe, In, Yb; 0 <= x <= 1.75; 0 <= y <= 3) is reported. The conductivities of a range of samples have been measured, with the highest value observed at 200°C being 2 × 10-4 ?-1cm-1 for Na1.75Mg1.75Cr0.25(SO4)3. The range of x for which single phase samples are observed depends on the nature of M' and M'', and on the value of y . Attempts to increase the Na content, and so increase the conductivity, by partially substituting the (S, Se)O4 groups by PO4 or SiO4 have proved unsuccessful.

Slater, P. R.; Greaves, C.

1993-11-01

217

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

UK PubMed Central (United Kingdom)

Structural sites occupied by lithium in the rhombohedral LiTi2-xZrx(PO4)3 series (0 < or = x < or = 2) have been investigated by 7Li NMR spectroscopy. At room temperature, the XRD patterns of the end-members of the series display rhombohedral R3c symmetry in LiTi2(PO4)3 and triclinic C in LiZr2(PO4)3. In the first compound, Li ions occupy M1 sites; however, in the second one Li occupy intermediate M1/2 sites. As the temperature increases, a first-order displacive transformation is detected in the triclinic phase, but a second-order/disorder transition is detected in the rhombohedral phase. From the temperature dependence of the 7Li NMR quadrupole constant (CQ) of the two compounds, the evolution of M1 and M1/2 sites occupancy in the 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.

Arbi K; París MA; Sanz J

2006-04-01

218

Transmission-type photonic crystal structures for color filters.  

UK PubMed Central (United Kingdom)

A transmission-type structure based on woodpile photonic crystal layers is proposed for use in color filters. Selective bandpass filters for red, green, and blue wavelength bands are constructed using optimally designed multilayered woodpile photonic crystals. The R/G/B color filtering for a wide range of incidence angles of light is demonstrated numerically, and the operation principle and design method are described.

Choi HJ; Choi S; Yoo YE; Jeon EC; Yi Y; Park S; Choi DS; Kim H

2013-07-01

219

The three-dimensional structural basis of type II hyperprolinemia.  

UK PubMed Central (United Kingdom)

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

Srivastava D; Singh RK; Moxley MA; Henzl MT; Becker DF; Tanner JJ

2012-07-01

220

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

 
 
 
 
221

Robust structural optimization using Gauss-type quadrature formula  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-01

222

Robust structural optimization using Gauss-type quadrature formula  

International Nuclear Information System (INIS)

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

2009-01-01

223

Robust Structural Optimization Using Gauss-type Quadrature Formula  

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-08-15

224

Robust Structural Optimization Using Gauss-type Quadrature Formula  

International Nuclear Information System (INIS)

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

2009-01-01

225

Structural determination of wild-type lactose permease  

DEFF Research Database (Denmark)

Here we describe an x-ray structure of wild-type lactose permease (LacY) from Escherichia coli determined by manipulating phospholipid content during crystallization. The structure exhibits the same global fold as the previous x-ray structures of a mutant that binds sugar but cannot catalyze translocation across the membrane. LacY is organized into two six-helix bundles with twofold pseudosymmetry separated by a large interior hydrophilic cavity open only to the cytoplasmic side and containing the side chains important for sugar and H(+) binding. To initiate transport, binding of sugar and/or an H(+) electrochemical gradient increases the probability of opening on the periplasmic side. Because the inward-facing conformation represents the lowest free-energy state, the rate-limiting step for transport may be the conformational change leading to the outward-facing conformation.

Guan, Lan; Mirza, Osman Asghar

2007-01-01

226

Structural insights into the Type II secretion nanomachine.  

UK PubMed Central (United Kingdom)

The Type II secretion nanomachine transports folded proteins across the outer membrane of Gram-negative bacteria. Recent X-ray crystallography, electron microscopy, and molecular modeling studies provide structural insights into three functionally and spatially connected units of this nanomachine: the cytoplasmic and inner membrane energy-harvesting complex, the periplasmic helical pseudopilus, and the outer membrane secretin. Key advances include cryo-EM reconstruction of the secretin and demonstration that it interacts with both secreted substrates and a crucial transmembrane clamp protein, plus a biochemical and structural explanation of the role of low-abundance pseudopilins in initiating pseudopilus growth. Combining structures and protein interactions, we synthesize a 3D view of the complete complex consistent with a stepwise pathway in which secretin oligomerization defines sites of nanomachine biogenesis.

McLaughlin LS; Haft RJ; Forest KT

2012-04-01

227

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

228

Ion conductivity of Nasicon ceramics: effects of texture and doping with B[sub 2]O[sub 3] and Al[sub 2]O[sub 3  

Energy Technology Data Exchange (ETDEWEB)

The Nasicon[sub ss], Na[sub 1+x]Zr[sub 2]Si[sub x]P[sub 3-x]O[sub 12], 0Nasicon ceramics. Ceramics of bulk composition Na[sub 2.94]Zr[sub 1.49]Si[sub 2.20]P[sub 0.80]O[sub 10.85] 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 3.65x10[sup 3] [Omega]cm to 1.23x10[sup 3] [Omega]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 [Omega]cm at 25 C. B[sub 2]O[sub 3]- and Al[sub 2]O[sub 3]-doping of the glass bearing Nasicon ceramic lower the room temperature resistivity by a factor 2 to 5. The dopants do not substitute into the Nasicon phase in substantial amounts. (orig.)

Hoej, J.W. (Inst. of Mineral Industry, Technical Univ., Lyngby (Denmark)); Engell, J. (Inst. of Mineral Industry, Technical Univ., Lyngby (Denmark))

1993-06-20

229

Specific features of the crystal structure of erbium polyphosphate of the structural type C  

Science.gov (United States)

Erbium polyphosphate Er(PO3)3 is synthesized at a temperature of 270°C from a polyphosphoric acid melt containing cerium, erbium, and phosphorus in the atomic ratio Cs: Er: P = 5: 1: 15. The crystal structure of the Er(PO3)3 polyphosphate synthesized is determined. The framework structure of the Er(PO3)3 polyphosphate is built up of infinite polyphosphate chains and ErO6 octahedra bonded to these chains. The structure is a derivative of the structural type C, in which a large number of trivalent metal polyphosphates crystallize. The main distinguishing feature of this structural type is an increase in the parameter b of the monoclinic unit cell of the Er(PO3)3 compound by a factor of 11 ( a = 10.040 Å, b = 73.482 Å, c = 11.268 Å, ? = 97.28°, space group Ia).

Murashova, E. V.; Chudinova, N. N.; Ilyukhin, A. B.

2007-03-01

230

Specific features of the crystal structure of erbium polyphosphate of the structural type C  

International Nuclear Information System (INIS)

Erbium polyphosphate Er(PO3)3 is synthesized at a temperature of 270 deg. C from a polyphosphoric acid melt containing cerium, erbium, and phosphorus in the atomic ratio Cs: Er: P = 5: 1: 15. The crystal structure of the Er(PO3)3 polyphosphate synthesized is determined. The framework structure of the Er(PO3)3 polyphosphate is built up of infinite polyphosphate chains and ErO6 octahedra bonded to these chains. The structure is a derivative of the structural type C, in which a large number of trivalent metal polyphosphates crystallize. The main distinguishing feature of this structural type is an increase in the parameter b of the monoclinic unit cell of the Er(PO3)3 compound by a factor of 11 (a = 10.040 A, b = 73.482 A, c = 11.268 A, ? = 97.28 deg., space group Ia).

2007-01-01

231

Structure and biophysics of type III secretion in bacteria.  

UK PubMed Central (United Kingdom)

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.

Chatterjee S; Chaudhury S; McShan AC; Kaur K; De Guzman RN

2013-04-01

232

Polysomatic series and superconductivity in complex cuprates with ladder-type structure  

International Nuclear Information System (INIS)

The structure of ladder-type cuprates was considered in polysomatic model. The possibility of the manifestation of superconductivity was estimated considering the structural stability of various cuprates with the ladder-type structure

1998-12-20

233

Polysomatic series and superconductivity in complex cuprates with ladder-type structure  

Energy Technology Data Exchange (ETDEWEB)

The structure of ladder-type cuprates was considered in polysomatic model. The possibility of the manifestation of superconductivity was estimated considering the structural stability of various cuprates with the ladder-type structure.

Leonyuk, L.; Maltsev, V. (Moscow State Univ. (Russian Federation)); Babonas, G.J.; Reza, A. (Semiconductor Physics Inst., Vilnius (Lithuania)); Szymczak, R. (Inst. of Physics, Warsaw (Poland))

1998-12-20

234

Syntheses, properties and applications of framework titanium phosphates with open structures  

Energy Technology Data Exchange (ETDEWEB)

A new layered hydrogen titanium phosphate (HTP) was synthesized by ion exchange of a precursor material NMe[sub 4]TP. This precursor, which was prepared from a hydrothermal reaction employing tetramethylammonium as a templating cation, also has a layered structure. The chemical formula of HTP was proposed as TiO[sub 2](H[sub 2]PO[sub 4])(H[sub 3]O). This was derived using [sup 31]P magic angle spinning solid state NMR, structural considerations, and other supplemental methods. A model for the structure of HTP was proposed in this study. HTP is capable of undergoing amine and redox lithium intercalations and the reactions show excellent reversibility. Each formula unit of HTP can take up one amine molecule or two lithium cations. Amines intercalate into HTP can take up one amine molecule or two lithium cations. Amines intercalate into HTP with a bilayer conformation and tilt at an angle of about 55 degrees relative to the layer slabs. Metal cations can also be incorporated into HTP under carefully controlled pH conditions or from the amine intercalates. The conductivity of the lithium cations intercalated into HTP was studied by ac impedance spectroscopy and is comparable to that of the NASICON type compounds. A Li/LiClO[sub 4]/HTP electrochemical cell was constructed and its discharge was studied. The discharge potential ranges between 2.6 and 1.8 volts and the energy density of this cell was estimated to be about 550 W[sup *]h/kg for the pure HTP material. The three dimensional titanium phosphates with the NASICON structure were also studied in this work. The hydrothermal process was used and investigated for the synthesis of MTi[sub 2](PO[sub 4])[sub 3], where M = Li[sup +], Na[sup +], K[sup +], Ag[sup +], or Cu[sup +]. Pure products were obtained under milder conditions than reported before. A comparison on the synthesis and properties of these NASICON compounds prepared from different processes is given.

Li, Y.J.

1994-01-01

235

Structure- and oil type-based efficacy of emulsion adjuvants.  

Science.gov (United States)

Oil-based emulsions are well-known immunopotentiators for inactivated, "killed" vaccines. We addressed the relationship between emulsion structure and levels of in vivo antibody formation to inactivated New Castle Disease virus (NDV) and Infectious Bronchitis virus (IBV) as antigens in 3-week-old chickens. The use of a polymeric emulsifier allowed for direct comparison of three types of emulsions, water-in-oil (W/O), oil-in-water (O/W) and W/O-in-water (W/O/W), while maintaining an identical content of components for each vehicle. They were prepared with either non-metabolizable, mineral oil or metabolizable, Miglyol 840. In addition, we assessed the inherent release capacity of each emulsion variant in vitro. Remarkably, we noted that W/O-type emulsions induced the best immune responses, while they released no antigen during 3 weeks. In general, mineral oil vaccines showed superior efficacy compared to Miglyol 840-based vaccines. PMID:16675072

Jansen, Theo; Hofmans, Marij P M; Theelen, Marc J G; Manders, Frans; Schijns, Virgil E J C

2006-04-17

236

Structure- and oil type-based efficacy of emulsion adjuvants.  

UK PubMed Central (United Kingdom)

Oil-based emulsions are well-known immunopotentiators for inactivated, "killed" vaccines. We addressed the relationship between emulsion structure and levels of in vivo antibody formation to inactivated New Castle Disease virus (NDV) and Infectious Bronchitis virus (IBV) as antigens in 3-week-old chickens. The use of a polymeric emulsifier allowed for direct comparison of three types of emulsions, water-in-oil (W/O), oil-in-water (O/W) and W/O-in-water (W/O/W), while maintaining an identical content of components for each vehicle. They were prepared with either non-metabolizable, mineral oil or metabolizable, Miglyol 840. In addition, we assessed the inherent release capacity of each emulsion variant in vitro. Remarkably, we noted that W/O-type emulsions induced the best immune responses, while they released no antigen during 3 weeks. In general, mineral oil vaccines showed superior efficacy compared to Miglyol 840-based vaccines.

Jansen T; Hofmans MP; Theelen MJ; Manders F; Schijns VE

2006-06-01

237

Caustic Recycle from Hanford Tank Waste Using NaSICON Ceramic Membranes  

International Nuclear Information System (INIS)

[en] 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

2008-07-15

238

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

239

Cooling structure for an engine in a straddled type vehicle  

Energy Technology Data Exchange (ETDEWEB)

A cooling structure is described for an engine in a dune buggy type vehicle provided with steerable left and right front wheels and an engine positioned at the center in a slanted direction to a vehicle body such as a four-wheel buggy car, the cooling structure comprising: a cooling fan disposed in front of the engine; an oil cooler engine radiator disposed adjacent to an upper half section of the cooling fan; and a pair of left and right upper frame members and a pair of left and right lower frame members extended in front of a handle rotary shaft from a vehicle body frame supporting the engine, at least a principal part of the oil cooler engine radiator being disposed within a space surrounded by the four frame members.

Inomata, F.; Iwadate, T.

1987-08-18

240

3D dynamic fluid structure coupling analysis of pool type LMFBR structures by substructuring method  

International Nuclear Information System (INIS)

A calculation method to take into account 3D geometry of shells and fluid structure interaction to pool type FBR structures is described in this paper. It is based on substructuring technique and substructures are defined by their natural modes. Application to the seismic behaviour of a reactor similar to SPX1 is amde and the results of this 3D calculations are compared to those calculated by 2D model.

1987-07-02

 
 
 
 
241

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

International Nuclear Information System (INIS)

[en] 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

1988-01-01

242

THE IMPORTANCE OF DISK STRUCTURE IN STALLING TYPE I MIGRATION  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-08-10

243

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.

244

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.

2011-01-01

245

Structural investigation of glasses belonging to the Na/sub 2/O-Nb/sub 2/O/sub 5/-P/sub 2/O/sub 5/ system  

Energy Technology Data Exchange (ETDEWEB)

The structure of glasses (with composition 0.855 (xNa/sub 2/O-yNb/sub 2/O/sub 5/-zP/sub 2/O/sub 5/)-0.145 Ln/sub 2/O/sub 3/; Ln = La, Nd, Eu, and x + y + z = 100) has been investigated by Raman scattering and optical spectroscopy using Nd/sup 3 +/ and Eu/sup 3 +/ as local structural probes. For the niobium-poor glasses (y < 12.5) octahedral NbO/sub 6/ groups are inserted within modified metaphosphate chains. In contrast the network former of the niobium-rich glasses ( y > 12.5) contains chains of NbO/sub 6/ octahedra sharing common corners. An intermediate situation seems to occur for y approx. 12.5 which preserves the Nasicon-type structure with all oxygen atoms common to NbO/sub 6/ and PO/sub 4/ groups.

El Jazouli, A.; Viala, J.C.; Parent, C.; Le Flem, G.; Hagenmuller, P.

1988-04-01

246

Electronic structure of p type Delta doped systems  

International Nuclear Information System (INIS)

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

1998-01-01

247

Polysulfones of new structural types as perspective antioxidant agents.  

UK PubMed Central (United Kingdom)

A series of polysulfones of new structural types on the basis of azanorbornenes, 2,2-diallyl-1,1,3,3-tetraethylguanidiniumchloride and tris(diethylamino)diallylaminophosphonium salts were obtained by free radical polymerization reaction. Their antioxidant properties in lipid peroxidation induced by iron/ascorbate and in erythrocyte hemolysis by H2O2 were evaluated. The polysulfone of 2,2-diallyl-1,1,3,3-tetraethylguanidinium chloride showed protection of erythrocytes against hydrogen peroxide and thermal shock, protected epithelial cells against UV irradiation, was not toxic for erythrocytes, epithelial cells SPEV and 3T3 fibroblasts. The polysulfone of N-benzyl-2-azanorbornene-5 inhibited lipid peroxidation in liver homogenate, did not exhibit cytotoxicity in SPEV and 3T3 cells, protected these against UV irradiation. Both compounds had low bioavailability and may be recommended for further investigations as excipients to be externally applied.

Gorbunova M; Anikina L

2013-05-01

248

Gradient type optimization methods for electronic structure calculations  

CERN Multimedia

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

Zhang, Xin; Wen, Zaiwen; Zhou, Aihui

2013-01-01

249

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

2009-03-30

250

Magnetic Structure of Rapidly Rotating FK Comae-Type Coronae  

CERN Multimedia

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

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

2010-01-01

251

``N'' structure for type-II superlattice photodetectors  

Science.gov (United States)

In the quest to raise the operating temperature and improve the detectivity of type II superlattice (T2SL) photodetectors, we introduce a design approach that we call the ``N structure.'' N structure aims to improve absorption by manipulating electron and hole wavefunctions that are spatially separated in T2SLs, increasing the absorption while decreasing the dark current. In order to engineer the wavefunctions, we introduce a thin AlSb layer between InAs and GaSb layers in the growth direction which also acts as a unipolar electron barrier. Unlike the symmetrical insertion of AlSb into GaSb layers, N design aims to exploit the shifting of the electron and hole wavefunctions under reverse bias. With cutoff wavelength of 4.3 ?m at 77 K, temperature dependent dark current and detectivity measurements show that the dark current density is 3.6 × 10-9 A/cm2, under zero bias. Photodetector reaches background limited infrared photodetection (BLIP) condition at 125 K with the BLIP detectivity (D*BLIP) of 2.6 × 1010 Jones under 300 K background and -0.3 V bias voltage.

Salihoglu, Omer; Muti, Abdullah; Kutluer, Kutlu; Tansel, Tunay; Turan, Rasit; Ergun, Yuksel; Aydinli, Atilla

2012-08-01

252

Type IIA orientifolds on SU(2)-structure manifolds  

International Nuclear Information System (INIS)

[en] 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.)

2010-01-01

253

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

254

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.; Jagiello Marina.; Kozina Zh.L.

2012-01-01

255

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

256

Electronic structure of binary phases with a hexagonal WC type structure  

International Nuclear Information System (INIS)

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

2001-01-01

257

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

International Nuclear Information System (INIS)

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

2012-03-28

258

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

Energy Technology Data Exchange (ETDEWEB)

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

Cormack, A. N.

2004-03-01

259

Structured layer applied on top of rick-type rotting structure with chimney  

UK PubMed Central (United Kingdom)

Structured layer (13) of particles sized 25-80 mm is applied on top of aerobic rick-type rotting arrangement, and covered with cover layer (12) to create biological filter layer. Residual waste (9) is first homogenized, reduced in size and soaked and placed in rick with chimney (3) to produce draught. The structured layer consists of screening residues produced in compost plants. The residual waste is deposited on air-permeable material such as wood pallets, through which slotted tubes extend. Air is drawn in through the slotted tubes, through the waste and into the chimney. The structured layer and the cover layer are each 15 cm thick. The passage for the slotted tube is formed by placing one pallet over a gap between two other pallets. The slotted tubes are PVC pipes. Three to six, preferably four, pallets are juxtaposed across the direction of the slotted tubes.

FABER KARL-WILHELM; COLLINS HANS JUERGEN PROF DR I; MAAK DIRK

260

Mass Structure of Axial Vector Types of Leptons and Fields  

CERN Multimedia

A classification of currents with respect to C-operation admits the existence of C-noninvariant types of Dirac fermions. Among them one can meet an electroweakly charged C-antisymmetrical leptons, the mass of which includes the electric and weak components responsible for the existence of their anapole charge, charge radius and electric dipole moment. Such connections can constitute the paraleptons of axial-vector currents, for example, at the interactions with field of spinless nuclei of true neutrality. We derive the united equations which relate the structural parts of mass to anapole, charge radius and electric dipole of any truly neutral lepton in the framework of flavour symmetry. Thereby, they establish the C-odd nature of leptons and fields at the level of constancy law of the size implied from the multiplication of a weak mass of C-antisymmetrical lepton by its electric mass. Therefore, all leptons of C-antisymmetricality regardless of the difference in masses of an axial-vector character, have the s...

Sharafiddinov, Rasulkhozha S

2011-01-01

 
 
 
 
261

Synthesis, crystal structure and spectroscopy properties of Na3AZr(PO4)3 (A=Mg, Ni) and Li2.6Na0.4NiZr(PO4)3 phosphates  

Science.gov (United States)

Na3AZr(PO4)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. Li2.6Na0.4NiZr(PO4)3 was synthesized through ion exchange from the sodium analog. These materials belong to the Nasicon-type structure. Raman spectra of Na3AZr(PO4)3 (A=Mg, Ni) phosphates present broad peaks in favor of the statistical distribution in the sites around PO4 tetrahedra. Diffuse reflectance spectra indicate the presence of octahedrally coordinated Ni2+ ions. Display Omitted

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

2006-06-01

262

Effect of synthesis procedure on the structure of sodium zirconium silicophosphates  

Energy Technology Data Exchange (ETDEWEB)

Sol-gel, hydrothermal, and classical high-temperature solid-state synthesis techniques were used to prepare stoichiometric and nonstoichiometric phases in the nasicon system, Na{sub 1+x}Zr{sub 2}Si{sub x}P{sub 3{minus}x}O{sub 12}. The results of neutron and x-ray powder data were used to explain the stoichiometry and structure of nasicon. These results suggest that the formation of nasicon is path-dependent. The results of the sol-gel preparations confirmed that stoichiometric nasicon can be formed but is unstable. There are definite structural differences among the products prepared by different techniques, with the sol-gel products having the more ordered structures. The formula Na{sub 1+4y+x}Zr{sub 2{minus}y{minus}z}Si{sub x}P{sub 3{minus}x}O{sub 12{minus}2z} is proposed to account for the observed stoichiometry. Significant differences are evident in the room-temperature conductivities as well as in the low-temperature (25{degree} to 180{degree}C) activation energies for the conduction process. However, above 180{degree}C both the slopes of the log {sigma} versus 1/T lines and the conductivities are very similar.

Moini, A.; Clearfield, A. (Texas A and M Univ., College Station (USA))

1987-04-01

263

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

Directory of Open Access Journals (Sweden)

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

Aleksandra KUTRZYK; Jan FILIPCZYK

2010-01-01

264

Changes in the internal structure of the human crystalline lens with diabetes mellitus type 1 and type 2.  

UK PubMed Central (United Kingdom)

PURPOSE: To investigate the effect of diabetes mellitus (DM) type 1 and type 2 on the internal structure of the lens. DESIGN: Observational cross-sectional study. PARTICIPANTS AND CONTROLS: One hundred seven patients with DM type 1, 106 patients with DM type 2, and 75 healthy control subjects. METHODS: Scheimpflug photography was used to image the lens of the right eye of 213 patients with DM and 75 healthy control subjects. The densitogram of the Scheimpflug image was used to indicate the nucleus and the different layers of the cortex of the lens. Lenses with cataract were excluded. MAIN OUTCOME MEASURES: The size of the nucleus and the different layers of the cortex of the lens. RESULTS: The nucleus and the different cortical layers of the DM type 1 lenses were significantly thicker compared with those of the control group (P<0.001). A significant association was found between the duration of DM type 1 and both the anterior and posterior cortex, its different layers, and the nucleus (P<0.001). The increase in the anterior and posterior cortex with the duration of DM was comparable with that of the nucleus. No important differences in the internal structure of the lens were found between the patients with DM type 2 and the control group. CONCLUSIONS: Diabetes mellitus type 1 has a significant effect on the internal structure of the lens. The difference in effect of DM type 1 and type 2 on internal lens structure suggests an essential difference in pathogenesis. Furthermore, the results of the present study may indicate that the increase in the size of the lens with DM type 1 is the result of a generalized swelling of the lens, affecting all its different parts.

Wiemer NG; Dubbelman M; Hermans EA; Ringens PJ; Polak BC

2008-11-01

265

Hamiltonian structure of Kadomtsev-Petviashvill: type equations  

Energy Technology Data Exchange (ETDEWEB)

A description of Hamiltonian structure and of the integrals of motion is given, in a general group-theoretic setting, for nonlinear equations with two space variables. The connections with a nonlocal Riemann problem, the multitime formalism, and the Hamiltonian structure of stationary problems are discussed.

Reiman, A.G.; Semenov-Tyan-Shanskii, M.A.

1985-12-20

266

On Tanaka's prolongation procedure for filtered structures of constant type  

CERN Document Server

We present the Tanaka prolongation procedure for filtered structures on manifolds in a spirit of Singer-Sternberg's description of the prolongation of the usual $G$-structure. It gives a transparent point of view on the Tanaka constructions avoiding many technicalities of the original Tanaka paper.

Zelenko, Igor

2009-01-01

267

Complete primary structure of human collagen type XIV (undulin).  

Science.gov (United States)

A partial cDNA sequence coding for the human extracellular matrix protein undulin has been completed. The completed sequence provides conclusive evidence for the suggested identity of undulin and collagen type XIV. Two differently sized polyproteins of 1780 and 1796 amino acids, with an overall amino acid sequence identity of 75% compared to chicken CXIV, emerge from variant 3' sequence ends encoding the C-terminal non-collagenous (NC) NC1 domain of human collagen type XIV. PMID:9427527

Bauer, M; Dieterich, W; Ehnis, T; Schuppan, D

1997-11-20

268

Complete primary structure of human collagen type XIV (undulin).  

UK PubMed Central (United Kingdom)

A partial cDNA sequence coding for the human extracellular matrix protein undulin has been completed. The completed sequence provides conclusive evidence for the suggested identity of undulin and collagen type XIV. Two differently sized polyproteins of 1780 and 1796 amino acids, with an overall amino acid sequence identity of 75% compared to chicken CXIV, emerge from variant 3' sequence ends encoding the C-terminal non-collagenous (NC) NC1 domain of human collagen type XIV.

Bauer M; Dieterich W; Ehnis T; Schuppan D

1997-11-01

269

Crystalline structure of magnets in Ticonal-type alloy  

International Nuclear Information System (INIS)

[en] Methods of X-ray diffraction analysis and X-ray diffraction topography are used to study crystal structure of alloy YuNDK35T5AA magnets. Lattice parameters are determined for ?- and ?'-phases which particle form a pseudomonocrystal. It is revealed that the magnets have pencil- or plate-like structure and developed substructure, the latter gives rise to scattering of a given [100] orientation and to macroscopic bending of a (100) plane. It is shown that the magnets contain different volume contents of additional parasitic crystallites. The data on the actual structure of the magnets are correlated with induction values in an air gap

2003-01-01

270

Derivations and structure of the Lie algebras of Xu type  

CERN Multimedia

We determine the derivation algebras and the isomorphism classes of a family of the simple Lie algebras introduced recently by Xu [Manuscripta Math 100 (1999), 489-518]. The structure space of these algebras is given explicitly.

Su, Y

2001-01-01

271

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

International Nuclear Information System (INIS)

[en] 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[ru] ???????? ???????????????? ??????? ? ??? 7Li ? 31P ??????????? ?????????? ?? ?????????? ??????? ??????? Li1-xZr2-xNbx(PO4)3 ? Li1+xZr2-xScx(PO4)3. ?? ?????? ?????????????? ??????? ???????? ????????? Li0.8Zr1.8Nb0.2(PO4)3. ????????, ??? ????????? ?????????????????? ? LiZr2(PO4)3 ????????????? ???????????? ??? ????????? ????????, ??? ? ??????????. ??? ???? ????????? ???????? ?????????? ????? ??????? ????????????. ????????? ?????? ?????? ??????????? ?????????????????? ? ?????????? ????????? ???????? ??? ????? ??????????

2002-01-01

272

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.

1992-01-01

273

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

274

Structures of the E46K mutant-type ?-synuclein protein and impact of E46K mutation on the structures of the wild-type ?-synuclein protein.  

UK PubMed Central (United Kingdom)

The E46K genetic missense mutation of the wild-type ?-synuclein protein was recently identified in a family of Spanish origin with hereditary Parkinson's disease. Detailed understanding of the structures of the monomeric E46K mutant-type ?-synuclein protein as well as the impact of the E46K missense mutation on the conformations and free energy landscapes of the wild-type ?-synuclein are required for gaining insights into the pathogenic mechanism of Parkinson's disease. In this study, we use extensive parallel tempering molecular dynamics simulations along with thermodynamic calculations to assess the secondary and tertiary structural properties as well as the conformational preferences of the monomeric wild-type and E46K mutant-type ?-synuclein proteins in an aqueous solution environment. We also present the residual secondary structure component conversion stabilities with dynamics using a theoretical strategy, which we most recently developed. To the best of our knowledge, this study presents the first detailed comparison of the structural and thermodynamic properties of the wild-type and E46K mutant-type ?-synuclein proteins in an aqueous solution environment at the atomic level with dynamics. We find that the E46K mutation results not only in local but also in long-range changes in the structural properties of the wild-type ?-synuclein protein. The mutation site shows a significant decrease in helical content as well as a large increase in ?-sheet structure formation upon E46K mutation. In addition, the ?-sheet content of the C-terminal region increases significantly in the E46K mutant-type ?S in comparison to the wild-type ?S. Our theoretical strategy developed to assess the thermodynamic preference of secondary structure transitions indicates that this shift in secondary structure is the result of a decrease in the thermodynamic preference of turn to helix conversions while the coil to ?-sheet preference increases for these residues. Long-range intramolecular protein interactions of the C-terminal with the N-terminal and NAC regions increase upon E46K mutation, resulting in more compact structures for the E46K mutant-type rather than wild-type ?S. However, the E46K mutant-type ?S structures are less stable than the wild-type ?S. Overall, our results show that the E46K mutant-type ?S has a higher propensity to aggregate than the wild-type ?S and that the N-terminal and C-terminal regions are reactive toward fibrillization and aggregation upon E46K mutation and we explain the associated reasons based on the structural properties herein. Small molecules or drugs that can block the specific residues forming abundant ?-sheet structure, which we report here, might help to reduce the reactivity of these intrinsically disordered fibrillogenic proteins toward aggregation and their toxicity.

Wise-Scira O; Dunn A; Aloglu AK; Sakallioglu IT; Coskuner O

2013-03-01

275

Learning and convergence analysis of neural-type structured networks.  

Science.gov (United States)

A class of feedforward neural networks, structured networks, has recently been introduced as a method for solving matrix algebra problems in an inherently parallel formulation. A convergence analysis for the training of structured networks is presented. Since the learning techniques used in structured networks are also employed in the training of neural networks, the issue of convergence is discussed not only from a numerical algebra perspective but also as a means of deriving insight into connectionist learning. Bounds on the learning rate are developed under which exponential convergence of the weights to their correct values is proved for a class of matrix algebra problems that includes linear equation solving, matrix inversion, and Lyapunov equation solving. For a special class of problems, the orthogonalized back-propagation algorithm, an optimal recursive update law for minimizing a least-squares cost functional, is introduced. It guarantees exact convergence in one epoch. Several learning issues are investigated. PMID:18276404

Polycarpou, M M; Ioannou, P A

1992-01-01

276

Learning and convergence analysis of neural-type structured networks.  

UK PubMed Central (United Kingdom)

A class of feedforward neural networks, structured networks, has recently been introduced as a method for solving matrix algebra problems in an inherently parallel formulation. A convergence analysis for the training of structured networks is presented. Since the learning techniques used in structured networks are also employed in the training of neural networks, the issue of convergence is discussed not only from a numerical algebra perspective but also as a means of deriving insight into connectionist learning. Bounds on the learning rate are developed under which exponential convergence of the weights to their correct values is proved for a class of matrix algebra problems that includes linear equation solving, matrix inversion, and Lyapunov equation solving. For a special class of problems, the orthogonalized back-propagation algorithm, an optimal recursive update law for minimizing a least-squares cost functional, is introduced. It guarantees exact convergence in one epoch. Several learning issues are investigated.

Polycarpou MM; Ioannou PA

1992-01-01

277

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

Directory of Open Access Journals (Sweden)

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

Igor Zelenko

2009-01-01

278

Topology of Type II REases revisited; structural classes and the common conserved core  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type II restriction endonucleases (REases) are deoxyribonucleases that cleave DNA sequences with remarkable specificity. Type II REases are highly divergent in sequence as well as in topology, i.e. the connectivity of secondary structure elements. A widely held assumption is that a structural core o...

Niv, Masha Y.; Ripoll, Daniel R.; Vila, Jorge A.; Liwo, Adam; Vanamee, Éva S.; Aggarwal, Aneel K.; Weinstein, Harel

279

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

280

Interpretation of harmonic structure in solar type II radio bursts  

Science.gov (United States)

Spectrographic and partly imaging observations of three Type II solar radio bursts displaying three drifting bands with frequencies related as 1¬2¬3 are discussed. The radio data of two of these events were simultaneousely recorded by the digital radiospectrograph of the Observatory of Solar Radioastronomy in Potsdam-Tremsdorf and the radioheliograph of the Paris-Meudon Observatory in Nançay. The data allow the brightness temperatures of radio emission in the three frequency bands to be determined. The second harmonic is traditionally explained as a result of coalescence of two plasma waves into an electromagnetic wave at twice the plasma frequency. Two nonlinear merging processes—the coalescence of three plasma waves, and of a plasma wave and an electromagnetic wave at twice the plasma frequency—are considered to explain the occurrence of the third harmonic on Type II dynamic spectra. The analysis shows that both processes can fit the observed brightness temperatures of the second and third harmonic. The first process acts preferably at low phase velocities of plasma waves and sharp electron density gradients in the source, and the second process dominates in the case of high plasma wave phase velocities. It is shown that the occurrence of the third harmonic in type II bursts due to nonlinear processes in the coronal plasma indicates not only a powerful event but also some specific conditions in the shock or foreshock region. Finally, we propose a method to distinguish between the two invoked nonlinear processes by a statistical investigation of Type II burst data.

Zlotnik, E. Ya.; Klassen, A.; Aurass, H.; Klein, K.-L.; Mann, G.

1998-01-01

 
 
 
 
281

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

International Nuclear Information System (INIS)

[en] 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

2004-01-01

282

Synthesis and characterization of a NaSICON series with general formula Na2.8Zr2-ySi1.8-4yP1.2+4yO12 (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 Na2.8Zr2-ySi1.8-4yP1.2+4yO12 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 Na2.8Zr1.775Si0.9P2.1O12 composition.

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

2004-12-01

283

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.)

1982-01-01

284

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

UK PubMed Central (United Kingdom)

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

Wang RH; Zhao YC; Gui JA

1987-12-01

285

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

Science.gov (United States)

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

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

1987-12-01

286

Modeling multi-typed structurally viewed chemicals with the UMLS Refined Semantic Network.  

UK PubMed Central (United Kingdom)

OBJECTIVE: Chemical concepts assigned multiple "Chemical Viewed Structurally" semantic types (STs) in the Unified Medical Language System (UMLS) are subject to ambiguous interpretation. The multiple assignments may denote the fact that a specific represented chemical (combination) is a conjugate, derived via a chemical reaction of chemicals of the different types, or a complex, composed of a mixture of such chemicals. The previously introduced Refined Semantic Network (RSN) is modified to properly model these varied multi-typed chemical combinations. DESIGN: The RSN was previously introduced as an enhanced abstraction of the UMLS's concepts. It features new types, called intersection semantic types (ISTs), each of which explicitly captures a unique combination of ST assignments in one abstract unit. The ambiguous ISTs of different "Chemical Viewed Structurally" ISTs of the RSN are replaced with two varieties of new types, called conjugate types and complex types, which explicitly denote the nature of the chemical interactions. Additional semantic relationships help further refine that new portion of the RSN rooted at the ST "Chemical Viewed Structurally." MEASUREMENTS: The number of new conjugate and complex types and the amount of changes to the type assignment of chemical concepts are presented. RESULTS: The modified RSN, consisting of 35 types and featuring 22 new conjugate and complex types, is presented. A total of 800 (about 98%) chemical concepts representing multi-typed chemical combinations from "Chemical Viewed Structurally" STs are uniquely assigned one of the new types. An additional benefit is the identification of a number of illegal ISTs and ST assignment errors, some of which are direct violations of exclusion rules defined by the UMLS Semantic Network. CONCLUSION: The modified RSN provides an enhanced abstract view of the UMLS's chemical content. Its array of conjugate and complex types provides a more accurate model of the variety of combinations involving chemicals viewed structurally. This framework will help streamline the process of type assignments for such chemical concepts and improve user orientation to the richness of the chemical content of the UMLS.

Chen L; Morrey CP; Gu H; Halper M; Perl Y

2009-01-01

287

Study on fluid-structure interaction of pool-type LMFBR reactor vessel  

International Nuclear Information System (INIS)

The pool type LMFBR reactor vessel contains many structures and a large amount of liquid sodium in it, in addition to being thin shell structure. Therefore, the fluid-structure interaction will become more predominant, and then should be considered for the seismic design of the pool type LMFBR. In this study, the authors investigated the fluid-structure interaction problems of the reactor vessel which has the bottom support arrangement as the core support system, in addition to the sloshing characteristics in the reactor vessel. The experimental results and the analytical results by FEM which took into account the interaction between fluid and structures were presented here

1987-07-02

288

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

1990-01-01

289

Large HI structures linked to southern O-type stars  

CERN Multimedia

In our search for interstellar bubbles around massive stars we analyze the environs of the O-type stars HD 38666, HD 124979, HD 163758, and HD 171589. The location of the stars, which are placed far from the galactic plane, favors the formation of large wind bubbles. We investigate the distribution of the neutral and ionized gas based on HI, CO, and radio continuum data, and that of the interstellar dust based on far infrared IRIS images. Here we report the discovery of neutral gas cavities and slowly expanding shells associated with the four massive stars. IR and optical counterparts were also detected for some of the stars. We discuss the probability that the features have originated in the action of the stellar winds on the surrounding gas.

Martín, M C; Romero, G A

2008-01-01

290

Topology of Type II REases revisited; structural classes and the common conserved core  

Science.gov (United States)

Type II restriction endonucleases (REases) are deoxyribonucleases that cleave DNA sequences with remarkable specificity. Type II REases are highly divergent in sequence as well as in topology, i.e. the connectivity of secondary structure elements. A widely held assumption is that a structural core of five ?-strands flanked by two ?-helices is common to these enzymes. We introduce a systematic procedure to enumerate secondary structure elements in an unambiguous and reproducible way, and use it to analyze the currently available X-ray structures of Type II REases. Based on this analysis, we propose an alternative definition of the core, which we term the ???-core. The ???-core includes the most frequently observed secondary structure elements and is not a sandwich, as it consists of a five-strand ?-sheet and two ?-helices on the same face of the ?-sheet. We use the ???-core connectivity as a basis for grouping the Type II REases into distinct structural classes. In these new structural classes, the connectivity correlates with the angles between the secondary structure elements and with the cleavage patterns of the REases. We show that there exists a substructure of the ???-core, namely a common conserved core, ccc, defined here as one ?-helix and four ?-strands common to all Type II REase of known structure.

Niv, Masha Y.; Ripoll, Daniel R.; Vila, Jorge A.; Liwo, Adam; Vanamee, Eva S.; Aggarwal, Aneel K.; Weinstein, Harel; Scheraga, Harold A.

2007-01-01

291

Large structures linked to southern O-type stars  

Scientific Electronic Library Online (English)

Full Text Available Abstract in spanish Analizamos la distribución del material interestelar en la vecindad de las estrellas de tipo O: HD 38666, HD 124979, HD 163758 y HD 171589, a fin de investigar la existencia de burbujas interestelares asociadas a las estrellas. La localization de las estrellas lejos del plano galáctico favorece la formación de burbujas de gran extensión. Con base en datos del , continuo de radio y CO, e imágenes en e (more) l infrarrojo lejano que revelan la emisión del polvo interestelar, investigamos la distribución del gas neutro e ionizado en estas regiones. Reportamos en este trabajo la detección de cavidades y envolturas en expansión en hidrógeno neutro, asociadas a las cuatro estrellas masivas. Se discute la posibilidad de que estas estructuras hayan sido originadas por la acción de los vientos estelares sobre el gas circundante. Abstract in english In our search for interstellar bubbles around massive stars we analyze the environs of the O-type stars HD 38666, HD 124979, HD 163758, and HD 171589. The location of the stars, far from the galactic plane, favors the formation of large wind bubbles. We investigate the distribution of the neutral and ionized gas based on , CO, and radio continuum data, and that of the interstellar dust based on far infrar (more) ed IRIS images. Here we report the discovery of neutral gas cavities and slowly expanding shells associated with the four massive stars. IR and optical counterparts were also detected for some of the stars. We discuss the probability that the features have originated by the action of stellar winds on the surrounding gas.

Martín, M. C.; Cappa, C. E.; Romero, G. A.

2009-04-01

292

Preparation of nasicon thin films by dip-coating on Si/SiO sub 2 wafers and corresponding C-V measurements. [Na-Zr-Si-P-O  

Energy Technology Data Exchange (ETDEWEB)

The dip-coating process, based on the sol-gel approach, has been studied for use in preparing Na{sup +} Super Ionic Conductor (NASICON) thin films. Differential thermal analysis (DTA) and X-ray analysis indicate a crystallization temperature of about 700deg C. The X-ray spectrum is consistent with that of NASICON ceramics. The first results obtained by the C-V method on electrolyte-oxide-semiconductor capacitors are very promising. To avoid crack initiation, the viscosity of the solution must be sufficiently low to give layer thicknesses less than 100 nm. Multidipping gives a better coating. (orig.).

Huang Yuanlong; Caneiro, A.; Attari, M.; Fabry, P. (Lab. d' Ionique et d' Electrochimie du Solide de Grenoble, ENSEEG, 38 - Saint Martin d' Heres (France))

1991-02-15

293

Structural aspects of gut peptides with therapeutic potential for type 2 diabetes.  

UK PubMed Central (United Kingdom)

Gut hormones represent a niche subset of pharmacologically active agents that are rapidly gaining importance in medicine. Due to their exceptional specificity for their receptors, these hormones along with their analogues have attracted considerable pharmaceutical interest for the treatment of human disorders including type 2 diabetes. With the recent advances in the structural biology, a significant amount of structural information for these hormones is now available. This Minireview presents an overview of the structural aspects of these hormones, which have roles in physiological processes such as insulin secretion, as well as a discussion on the relevant structural modifications used to improve these hormones for the treatment of type 2 diabetes.

Hewage CM; Venneti KC

2013-04-01

294

A physiological and structural study of neuron types in the cochlear nucleus. II. Neuron types and their structural correlation with response properties.  

UK PubMed Central (United Kingdom)

The present study examined the morphological cell types of neurons labeled with intracellular horseradish peroxidase injections, many of them following electrophysiological recordings in the cochlear nucleus of gerbils and chinchillas. Most of the subdivisions and neuronal types previously described in the cat were identified in the present material, including spherical and globular bushy cells, stellate, bushy multipolar, elongate, octopus, and giant cells in the ventral cochlear nucleus, and a cartwheel cell in the dorsal cochlear nucleus. In many cases these structurally distinct neurons were correlated with their characteristic responses to stimulation by sound or intracellular injection of depolarizing current. The dendritic terminals of the elongate, antenniform, and clavate cells of the posteroventral cochlear nucleus link each of these cell types with neighboring structures in distinct patterns, which may provide a basis for differences in synaptic organization. These cell types differ from each other and from the stellate cells of the anteroventral cochlear nucleus. Despite their heterogeneous morphology, most of these neurons had a regular discharge in response to stimulation (choppers). Irregularly firing neurons (primary-like) had very different structures, e.g., the spherical and globular bushy cells and the bushy multipolar neuron. They, too, represent a heterogeneous population. An onset neuron was identified as an octopus cell. This paper compares the morphological observations with the electrophysiological properties of different cell types reported in a companion paper (Feng et al. [1994] J. Comp. Neurol.). Together, these findings imply that response properties may be partially independent of neuronal structure. Morphologically distinct neurons can generate similar temporal patterns in response to simple acoustic stimuli. Nevertheless, the synaptic organization of these different neuron types, including their connections, would be expected to affect or alter the cells' responses to appropriate stimuli. The possibility is raised that membrane properties and synaptic organization complement and interact with each other.

Ostapoff EM; Feng JJ; Morest DK

1994-08-01

295

Temperature dependent XAFS studies of local atomic structure of the perovskite-type zirconates  

International Nuclear Information System (INIS)

Temperature dependent preedge and extended x-ray absorption fine structure measurements at the Zr K edge for the perovskite-type zirconates PbZr0.515Ti0.485O3 (PZT), PbZrO3 (PZ), and BaZrO3 are performed. To carry out a more accurate study of the weak reconstruction of the local atomic structure we employed a combination of two techniques: (i) analysis of the preedge fine structure, and (ii) analysis of the Fourier transform of the difference between ?(k) functions obtained at different temperatures. A detailed investigation of local atomic structure in the cubic phase for all the crystals is also performed. It is shown that neither the displacive nor the order-disorder model can describe correctly the changes of local atomic structure during phase transitions in PZ and PZT. A spherical model describing the local atomic structure of perovskite-type crystals suffering structural phase transitions is proposed.

2006-04-01

296

Fabrication and characterization of NASICON ceramic electrolytes. Final technical progress report, November 1, 1978-March 31, 1980  

Energy Technology Data Exchange (ETDEWEB)

Scaled-up fabrication procedures have been developed for NASICON (Na/sub 1 + x/Zr/sub 2/Si/sub x/P/sub 3 - x/O/sub 12/) electrolytes (x = 2.0) involving (1) the mechanical mixing of raw materials (Na/sub 3/PO/sub 4/ 12H/sub 2/O, SiO/sub 2/, and ZrO/sub 2/), (2) calcination at 1160/sup 0/C, (3) dry ball milling, (4) isostatic pressing, and (5) sintering at 1230 to 1260/sup 0/C (4 to 24 h). Electrolyte tubes (16mm OD by 200mm long) possess acceptable dimensional tolerances, mass densities over 3.20 g/cm/sup 3/, sodium ion resistivities under 5 ohm-cm at 300/sup 0/C and diametral strengths of approximately 70 to 80 MPa. These electrolytes, which contain a small residual amount (up to about 5%) of free zirconia (ZrO/sub 2/), have demonstrated very poor static corrosion resistance in liquid sodium at 300 to 400/sup 0/C and very low endurance (0.2 to 1.4 Ah/cm/sup 2/ of charge passed at current densities up to 56 mA/cm/sup 2/) in sodium-sodium test cells operated at 300 to 340/sup 0/C.

1980-06-01

297

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

Science.gov (United States)

We determined the chromosomal localization and structure of the gene encoding human type II inosine 5(prime)-monophosphate dehydrogenase (IMPDH, EC 1.1.1.205), an enzyme associated with cellular proliferation, malignant transformation, and differentiation...

D. Glesne E. Huberman F. Collart T. Varkony H. Drabkin

1994-01-01

298

Ginzburg-Landau-type theory of antiphase boundaries in polytwinned structures  

CERN Multimedia

The conventional Landau-Ginzburg theory of interphase boundaries is generalized to the case of not small values of order parameters, with application to polytwinned structures characteristic of cubic-tetragonal-type phase transitions. Explicit expressions for the structure and energy of antiphase boundaries via the functions entering the free energy functional are given. A peculiar dependence of equilibrium orientations of antiphase boundaries on the interaction type is predicted, and it qualitatively agrees with available experimental data

Vaks, V G

2001-01-01

299

Dung beetle assemblage structure in Tswalu Kalahari Reserve: responses to a mosaic of landscape types, vegetation communities, and dung types.  

Science.gov (United States)

Tswalu Kalahari Reserve is a private game reserve covering 1,020 km(2) in the Northern Cape, South Africa. It has been created from a number of reclaimed farms and restocked with large indigenous mammals. Two surveys were conducted to inventory the dung beetle fauna (Coleoptera: Scarabaeidae: Scarabaeinae) and determine their spatial patterns and food type associations. The spatial survey used pig dung-baited pitfall traps to examine dung beetle distribution across three main landscape types (plains, dunes, hills) comprising six principal vegetation communities. The food study examined their relative associations with carrion and four different dung types within a single vegetation community. A total of 70 species was recorded. Because the food association study was spatially restricted and conducted under drought conditions, abundance and species richness (47 species) were much lower than in the spatial study (64 species), which was conducted after substantial rainfall. Principal spatial differences in species abundance structure of assemblages were between the sandy southwest plains and dunes; the sandy northern dune fields and plains; and the rocky hills. Forty species analyzed in the food association study showed clear distributional biases to carrion or the dung of elephant (monogastric herbivore), pig (omnivore), cattle and sheep (ruminant herbivores), or pig and cattle. The results (1) show how dung beetle assemblage structure is locally diversified across the heterogeneous landscape of the reserve and (2) indicate how the different dung types dropped by a diverse assemblage of indigenous mammals may variously favor different species of dung beetles. PMID:20550793

Davis, Adrian L V; Scholtz, Clarke H; Kryger, Ute; Deschodt, Christian M; Strümpher, Werner P

2010-06-01

300

Dung beetle assemblage structure in Tswalu Kalahari Reserve: responses to a mosaic of landscape types, vegetation communities, and dung types.  

UK PubMed Central (United Kingdom)

Tswalu Kalahari Reserve is a private game reserve covering 1,020 km(2) in the Northern Cape, South Africa. It has been created from a number of reclaimed farms and restocked with large indigenous mammals. Two surveys were conducted to inventory the dung beetle fauna (Coleoptera: Scarabaeidae: Scarabaeinae) and determine their spatial patterns and food type associations. The spatial survey used pig dung-baited pitfall traps to examine dung beetle distribution across three main landscape types (plains, dunes, hills) comprising six principal vegetation communities. The food study examined their relative associations with carrion and four different dung types within a single vegetation community. A total of 70 species was recorded. Because the food association study was spatially restricted and conducted under drought conditions, abundance and species richness (47 species) were much lower than in the spatial study (64 species), which was conducted after substantial rainfall. Principal spatial differences in species abundance structure of assemblages were between the sandy southwest plains and dunes; the sandy northern dune fields and plains; and the rocky hills. Forty species analyzed in the food association study showed clear distributional biases to carrion or the dung of elephant (monogastric herbivore), pig (omnivore), cattle and sheep (ruminant herbivores), or pig and cattle. The results (1) show how dung beetle assemblage structure is locally diversified across the heterogeneous landscape of the reserve and (2) indicate how the different dung types dropped by a diverse assemblage of indigenous mammals may variously favor different species of dung beetles.

Davis AL; Scholtz CH; Kryger U; Deschodt CM; Strümpher WP

2010-06-01

 
 
 
 
301

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

Directory of Open Access Journals (Sweden)

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

Novak Kerry; Mandin Henry; Wilcox Elizabeth; McLaughlin Kevin

2006-01-01

302

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

Directory of Open Access Journals (Sweden)

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

Changsung Kim; Joongu Kang; Hongkoo Yeo

2012-01-01

303

The N=4 effective action of type IIA supergravity compactified on SU(2)-structure manifolds  

CERN Document Server

We study compactifications of type IIA supergravity on six-dimensional manifolds with SU(2) structure and compute the low-energy effective action in terms of the non-trivial intrinsic torsion. The consistency with gauged N=4 supergravity is established and the gauge group is determined. Depending on the structure of the intrinsic torsion, antisymmetric tensor fields can become massive.

Danckaert, Thomas; Martínez-Pedrera, Danny; Spanjaard, Bastiaan; Triendl, Hagen

2011-01-01

304

Expert system for rational type structure and working resistance selection of hydraulic powered support  

Energy Technology Data Exchange (ETDEWEB)

This paper introduces the design of an expert system for a rational type, structure and working resistance selection of a hydraulic powered support, including the knowledge bank, structure and uncertainty inference method. The application shows that the expert system is high in reliability and practice. 3 refs.

Zhao Hangshan; Yao Jiangguo; Si Yuanwei; Chang Huiming [Central Coal Mining Research Institute, Beijing (China). Beijing Research Institute of Coal Mining

1994-12-31

305

Structure refinement of decagonal Al-Ni-Co, superstructure type I  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract The structure of decagonal Al-Ni-Co, superstructure type I (so called Edagawa phase) was refined in the physical space. A statistical approach was used to calculate the structure factor based on the rhombic Penrose This tiling, with tile edge length 12.1 Å, as reference frame. A tot...

306

Structure of Thermus thermophilus type 2 isopentenyl diphosphate isomerase inferred from crystallography and molecular dynamics.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Crystal structures of Thermus thermophilus and Bacillus subtilis type 2 IPP isomerases were combined to generate an almost complete model of the FMN-bound structure of the enzyme. In contrast to previous studies, positions of flexible loops were obtained and carefully analyzed by molecular dynamics....

de Ruyck, Jérôme; Rothman, Steven C; Poulter, C Dale; Wouters, Johan

307

A Higher Order Analysis of the Factor Structure of the Myers-Briggs Type Indicator.  

Science.gov (United States)

|Examines the higher order structure of Form G of the Myers Briggs Type Indicator. A third order component analysis of a sample (N=926) found two higher order components. This higher order analysis contributes to the research literature pertaining to the generalized structure of the personality measure. (Contains 44 references and 1 table.) (GCP)|

Johnson, William L.; Mauzey, Edward; Johnson, Annabel M.; Murphy, Stanley D.; Zimmerman, Kurt J.

2001-01-01

308

Foot type biomechanics part 1: structure and function of the asymptomatic foot.  

UK PubMed Central (United Kingdom)

BACKGROUND: Differences in foot structure are thought to be associated with differences in foot function during movement. Many foot pathologies are of a biomechanical nature and often associated with foot type. Fundamental to the understanding of foot pathomechanics is the question: do different foot types have distinctly different structure and function? AIM: To determine if objective measures of foot structure and function differ between planus, rectus and cavus foot types in asymptomatic individuals. METHODS: Sixty-one asymptomatic healthy adults between 18 and 77 years old, that had the same foot type bilaterally (44 planus feet, 54 rectus feet, and 24 cavus feet), were recruited. Structural and functional measurements were taken using custom equipment, an emed-x plantar pressure measuring device, a GaitMat II gait pattern measurement system, and a goniometer. Generalized Estimation Equation modeling was employed to determine if each dependent variable of foot structure and function was significantly different across foot type while accounting for potential dependencies between sides. Post hoc testing was performed to assess pair wise comparisons. RESULTS: Several measures of foot structure (malleolar valgus index and arch height index) were significantly different between foot types. Gait pattern parameters were invariant across foot types. Peak pressure, maximum force, pressure-time-integral, force-time-integral and contact area were significantly different in several medial forefoot and arch locations between foot types. Planus feet exhibited significantly different center of pressure excursion indices compared to rectus and cavus feet. CONCLUSIONS: Planus, rectus and cavus feet exhibited significantly different measures of foot structure and function.

Hillstrom HJ; Song J; Kraszewski AP; Hafer JF; Mootanah R; Dufour AB; Chow BS; Deland JT 3rd

2013-03-01

309

Influence of thermal cycling on properties of NASICON. [Na/sub 3/Zr/sub 2/Si/sub 2/PO/sub 12/  

Energy Technology Data Exchange (ETDEWEB)

The influence of thermal cycling on the bulk and grain boundary conductivities and on microhardness of Na/sub 3/Zr/sub 2/Si/sub 2/PO/sub 12/ (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/mm/sup 2/.

Bogusz, W. (Politechnika Warszawska (Poland). Inst. Fizyki)

1981-08-16

310

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

311

Structural investigation of Eu2+ emissions from alkaline earth zirconium phosphate  

Science.gov (United States)

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.

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

2009-04-01

312

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

313

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

International Nuclear Information System (INIS)

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

1989-11-03

314

Structural analysis and ion translocation mechanisms of the muscle-type acetylcholine receptor channel.  

UK PubMed Central (United Kingdom)

PURPOSE: The aim of this work is to analyze the conformational changes in the acetylcholine receptor caused by channel opening and to investigate the electrostatic profile during ion translocation through the channel. METHODS: A computational model of the human muscle-type acetylcholine receptor (AChR) was built and used to analyze channel structure and its interactions with different ions. Using the Torpedo AChR crystal structure as a homologous template, the 3D structure of the human muscle-type AChR was reconstructed. RESULTS: This first model is optimized and an open structure of the channel is generated using Normal Mode Analysis in order to assess morphologic and energetic differences between open and closed structures. In addition, the issue of ion translocation is investigated in further detail. Results elucidate different aspects of the channel: channel gate structure, channel interactions with translocating ions, differences between muscle-type AChR and previous neuronal-type AChR models. CONCLUSIONS: The model constructed here is ideal for further computational studies on muscle-type AChR and its pathologic mutations.

Ugolini GS; Gautieri A; Redaelli A; Soncini M

2013-01-01

315

Structural Safety Analysis Report for the Type A Radioactive Waste Transport Package  

Energy Technology Data Exchange (ETDEWEB)

We carried out structural safety evaluation for the type A radioactive waste transport package. Requirements for type A packages according to the related regulations such as IAEA Safety Standard Series No. TS-R-1, Korea Most Act. 2001-23 and US 10 CFR Part 71 were evaluated. General requirements for packages such as those for a lifting attachment, a tie-down attachment and pressure condition. The structural analyses and tests under the normal transport conditions such as free drop test condition and penetration test condition were carried out for the type A radioactive waste transport packages. Also the analysis of stacking condition was conducted. The type A radioactive waste transport packages were maintained the structural integrities.

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

2006-09-15

316

Structural Safety Analysis Report for the Type A Radioactive Waste Transport Package  

International Nuclear Information System (INIS)

We carried out structural safety evaluation for the type A radioactive waste transport package. Requirements for type A packages according to the related regulations such as IAEA Safety Standard Series No. TS-R-1, Korea Most Act. 2001-23 and US 10 CFR Part 71 were evaluated. General requirements for packages such as those for a lifting attachment, a tie-down attachment and pressure condition. The structural analyses and tests under the normal transport conditions such as free drop test condition and penetration test condition were carried out for the type A radioactive waste transport packages. Also the analysis of stacking condition was conducted. The type A radioactive waste transport packages were maintained the structural integrities

2006-01-01

317

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

Directory of Open Access Journals (Sweden)

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

J Ker

2010-01-01

318

Crystallochemistry and properties of compounds with rhombohedral frameworks of the [[Msub(2)(EOsub(4))sub(3)]sup(p-)]sub(3infinity) type and of the solid solutions on their basis  

International Nuclear Information System (INIS)

[en] Results of investigations into compounds and solid solutions with rhombohedral frameworks of ([Msub(2)(EhOsub(4))sub(3)] sup(p-))sub(3) infinity type (M-tri- or tetravalent cation, Eh-P, Si, Ge) are generalized. Conditions for existence of phases close by structure and properties to sodium-zirconium silicophosphate of approximate composition Na3Zr2Si2PO12 (NASICON) are analyzed, and effect of different substitutions in the framework on structural and electrophysical characteristics of these phases is stated. Impossibility of existing single-phase rhombohedral Na3Zr2Si2PO12 and Na3M2(PO4)3 (M-Lusub(x)-Er, In, Y) is substantiated. Highest values of conductivity are attained for compounds with rhombohedral frameworks of ([Msub(2)(POsub(4))sub(3)]sup(p-))sub(3) infinite type at dimensions of hexagonal rings between cavities close to maximum possible for the given structural type and at population of these framework cavities by Na+ cations by approximately 3/4

1986-01-01

319

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

International Nuclear Information System (INIS)

[en] 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

1987-01-01

320

Thermodynamics of NASICON (Na/sub 1+x/Zr/sub 2/Si/sub x/P/sub 3-x/O/sub 12/)  

Energy Technology Data Exchange (ETDEWEB)

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

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

1988-01-01

 
 
 
 
321

Structural Safety Analysis Report of Type IP-2 Radioactive Waste transport Package  

International Nuclear Information System (INIS)

We carried out structural safety evaluation for the two kinds of type IP-2 package to transport safely radioactive waste drum with using the different thickness steel shell as a shielding material, which is classified as LSA(Low Specific Activity)-II, LSA-III and SCO(Surface Contaminated Object)-II in accordance with IAEA Safety Standard Series No. TS-R-1, Korea Most Act. 2001-23 and US 10 CFR Part 71. The structural analyses of free drop condition and stacking condition under the normal transport conditions were carried out for the type IP-2 radioactive waste transport packages. The drop tests were conducted for two kinds of a transport package. The type IP-2 radioactive waste transport packages were maintained the structural integrities

2006-01-01

322

Structural Safety Analysis Report of Type IP-2 Radioactive Waste transport Package  

Energy Technology Data Exchange (ETDEWEB)

We carried out structural safety evaluation for the two kinds of type IP-2 package to transport safely radioactive waste drum with using the different thickness steel shell as a shielding material, which is classified as LSA(Low Specific Activity)-II, LSA-III and SCO(Surface Contaminated Object)-II in accordance with IAEA Safety Standard Series No. TS-R-1, Korea Most Act. 2001-23 and US 10 CFR Part 71. The structural analyses of free drop condition and stacking condition under the normal transport conditions were carried out for the type IP-2 radioactive waste transport packages. The drop tests were conducted for two kinds of a transport package. The type IP-2 radioactive waste transport packages were maintained the structural integrities.

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

2006-09-15

323

Multilocus PCR typing strategy for differentiation of Staphylococcus aureus siphoviruses reflecting their modular genome structure.  

UK PubMed Central (United Kingdom)

Given the great biological importance and high diversity of temperate Staphylococcus aureus bacteriophages, a method is needed for the description of their genomic structure. Here we have updated a multiplex PCR strategy for the complex characterization of S. aureus phages of the family Siphoviridae. Based on the comparative genomic analysis of the available phage sequences, a multilocus PCR strategy for typing the major modules of the phage genome was designed. The genomic modules were classified on the basis of the genes for integrase (10 types), anti-repressor (five types), replication proteins polA, dnaC and dnaD (four types), dUTPase (four types), portal protein (eight types), tail appendices (four types) and endolysin (four types) corresponding to the integrase locus, lysogeny control region, and modules for DNA replication, transcription regulation, packaging, tail appendices and lysis respectively. The nine PCR assays designed for the above sequences were shown to be capable to identify the bacteriophage gene pool present both in the phage and bacterial genomes and their extensive mosaic structure. The established multiplex PCR-based multilocus diagnostic scheme is convenient for rapid and reliable phage and prophage classification and for the study of bacteriophage evolution.

Kahánková J; Pant??ek R; Goerke C; R?ži?ková V; Holochová P; Doška? J

2010-09-01

324

Multilocus PCR typing strategy for differentiation of Staphylococcus aureus siphoviruses reflecting their modular genome structure.  

Science.gov (United States)

Given the great biological importance and high diversity of temperate Staphylococcus aureus bacteriophages, a method is needed for the description of their genomic structure. Here we have updated a multiplex PCR strategy for the complex characterization of S. aureus phages of the family Siphoviridae. Based on the comparative genomic analysis of the available phage sequences, a multilocus PCR strategy for typing the major modules of the phage genome was designed. The genomic modules were classified on the basis of the genes for integrase (10 types), anti-repressor (five types), replication proteins polA, dnaC and dnaD (four types), dUTPase (four types), portal protein (eight types), tail appendices (four types) and endolysin (four types) corresponding to the integrase locus, lysogeny control region, and modules for DNA replication, transcription regulation, packaging, tail appendices and lysis respectively. The nine PCR assays designed for the above sequences were shown to be capable to identify the bacteriophage gene pool present both in the phage and bacterial genomes and their extensive mosaic structure. The established multiplex PCR-based multilocus diagnostic scheme is convenient for rapid and reliable phage and prophage classification and for the study of bacteriophage evolution. PMID:20406289

Kahánková, Jana; Pant??ek, Roman; Goerke, Christiane; R?ži?ková, Vladislava; Holochová, Pavla; Doška?, Ji?í

2010-04-16

325

Structural and biochemical analyses of regio- and stereospecificities observed in a type II polyketide ketoreductase.  

Science.gov (United States)

Type II polyketides include antibiotics such as tetracycline and chemotherapeutics such as daunorubicin. Type II polyketides are biosynthesized by the type II polyketide synthase (PKS) that consists of 5-10 stand-alone domains. In many type II PKSs, the type II ketoreductase (KR) specifically reduces the C9-carbonyl group. How the type II KR achieves such a high regiospecificity and the nature of stereospecificity are not well understood. Sequence alignment of KRs led to a hypothesis that a well-conserved 94-XGG-96 motif may be involved in controlling the stereochemistry. The stereospecificity of single-, double-, and triple-mutant combinations of P94L, G95D, and G96D were analyzed in vitro and in vivo for the actinorhodin KR (actKR). The P94L mutation is sufficient to change the stereospecificity of actKR. Binary and ternary crystal structures of both wild-type and P94L actKR were determined. Together with assay results, docking simulations, and cocrystal structures, a model for stereochemical control is presented herein that elucidates how type II polyketides are introduced into the substrate pocket such that the C9-carbonyl can be reduced with high regio- and stereospecificities. The molecular features of actKR important for regio- and stereospecificities can potentially be applied in biosynthesizing new polyketides via protein engineering that rationally controls polyketide keto reduction. PMID:21506596

Javidpour, Pouya; Korman, Tyler Paz; Shakya, Gaurav; Tsai, Shiou-Chuan

2011-05-04

326

Structural and biochemical analyses of regio- and stereospecificities observed in a type II polyketide ketoreductase.  

UK PubMed Central (United Kingdom)

Type II polyketides include antibiotics such as tetracycline and chemotherapeutics such as daunorubicin. Type II polyketides are biosynthesized by the type II polyketide synthase (PKS) that consists of 5-10 stand-alone domains. In many type II PKSs, the type II ketoreductase (KR) specifically reduces the C9-carbonyl group. How the type II KR achieves such a high regiospecificity and the nature of stereospecificity are not well understood. Sequence alignment of KRs led to a hypothesis that a well-conserved 94-XGG-96 motif may be involved in controlling the stereochemistry. The stereospecificity of single-, double-, and triple-mutant combinations of P94L, G95D, and G96D were analyzed in vitro and in vivo for the actinorhodin KR (actKR). The P94L mutation is sufficient to change the stereospecificity of actKR. Binary and ternary crystal structures of both wild-type and P94L actKR were determined. Together with assay results, docking simulations, and cocrystal structures, a model for stereochemical control is presented herein that elucidates how type II polyketides are introduced into the substrate pocket such that the C9-carbonyl can be reduced with high regio- and stereospecificities. The molecular features of actKR important for regio- and stereospecificities can potentially be applied in biosynthesizing new polyketides via protein engineering that rationally controls polyketide keto reduction.

Javidpour P; Korman TP; Shakya G; Tsai SC

2011-05-01

327

Teichm\\"uller Structures and Dual Geometric Gibbs Type Measure Theory for Continuous Potentials  

CERN Document Server

The Gibbs measure theory for smooth potentials is an old and beautiful subject and has many important applications in modern dynamical systems. For continuous potentials, it is impossible to have such a theory in general. However, we develop a dual geometric Gibbs type measure theory for certain continuous potentials in this paper following some ideas and techniques from Teichm\\"uller theory for Riemann surfaces. Furthermore, we prove that the space of those continuous potentials has a Teichm\\"uller structure. Moreover, this Teichm\\"uller structure is a complete structure and is a completion of the space of smooth potentials under this Teichm\\"uller structure. Thus our dual geometric Gibbs type theory is a completion of the Gibbs measure theory for smooth potentials from the dual geometric point of view.

Jiang, Yunping

2008-01-01

328

Structural investigation of Eu2+ emissions from alkaline earth zirconium phosphate  

International Nuclear Information System (INIS)

[en] 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.

2009-01-01

329

Stability of coordination polyhedrons and structural types in rare earth chalcogenides  

Energy Technology Data Exchange (ETDEWEB)

A new method of forecasting crystal structure for compounds with mainly ion bond has been suggested and realized for the class of binary chalcogenides of rare earths (RE). Using the ion model the lower boundaries of stability for 21 types of coordination polyhedrons, corresponding to coordination numbers from 3 to 9, are calculated. The dependence of the polyhedron stability boundaries on the distortion degree is detected. On the basis of the Sandersen method the radii of chalcogenes and RE for different coordination numbers are calculated. Taking into account various coordination possibilities of RE, the most probable structural types for each combination RE-chalishedcogene are established.

Kuz' micheva, G.M.; Voloshin, A.Eh.; Eliseev, A.A. (Moskovskij Inst. Tonkoj Khimicheskoj Tekhnologii (USSR))

1984-06-01

330

Isolation and structure of hematoside-type ganglioside from the starfish Linckia laevigata.  

UK PubMed Central (United Kingdom)

A hematoside-type ganglioside, LLG-1 (1), has been obtained from the polar lipid fraction of the chloroform/methanol extract of the starfish Linckia laevigata. The structure of the ganglioside has been determined on the basis of chemical and spectroscopic evidence as 1-O-[N-glycolyl-alpha-D-neuraminosyl-(2-->3)-beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranosyl]-ceramide. The ceramide moiety was composed of heterogeneous 2-hydroxy fatty acid and phytosphingosine units. This is the first report on the isolation and structure elucidation of naked hematoside-type ganglioside from echinoderms.

Inagaki M; Saito T; Miyamoto T; Higuchi R

2009-02-01

331

Isolation and structure of hematoside-type ganglioside from the starfish Linckia laevigata.  

Science.gov (United States)

A hematoside-type ganglioside, LLG-1 (1), has been obtained from the polar lipid fraction of the chloroform/methanol extract of the starfish Linckia laevigata. The structure of the ganglioside has been determined on the basis of chemical and spectroscopic evidence as 1-O-[N-glycolyl-alpha-D-neuraminosyl-(2-->3)-beta-D-galactopyranosyl-(1-->4)-beta-D-glucopyranosyl]-ceramide. The ceramide moiety was composed of heterogeneous 2-hydroxy fatty acid and phytosphingosine units. This is the first report on the isolation and structure elucidation of naked hematoside-type ganglioside from echinoderms. PMID:19182413

Inagaki, Masanori; Saito, Takeshi; Miyamoto, Tomofumi; Higuchi, Ryuichi

2009-02-01

332

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

Directory of Open Access Journals (Sweden)

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

Listopadov ?.?.; Lepilin A.M.; Konnov V.V.; Gavryushova L.V.; Arushanyan A.R.

2010-01-01

333

Arterial wall structure and dynamics in type 2 diabetes mellitus methodological aspects and pathophysiological findings.  

Science.gov (United States)

Type 2 Diabetes Mellitus (DM), or adult-onset diabetes, is being considered as a new pandemic. Cardiovascular disease is the major cause of morbidity and mortality in type 2 DM, due to arterial structure and functional changes. Assessment of arterial structure and biomechanics, by non-invasive methods and parameters, can be used to detect early alterations related to DM. Three markers of vascular disease may help to a better evaluation of vascular dysfunction in type 2 DM patients: carotid intimamedia thickness (IMTc), arterial stiffness, assessed by pulse wave velocity (PWV), and endothelial function, evaluated through the brachial artery flow-mediated dilation (FMD). Among these parameters, IMTc is considered a marker of structural vessel wall properties, and arterial stiffness reflects functional wall properties. Endothelial function represents the arterial way to actively regulate its diameter (smooth muscle-dependent actions) and its visco-elastic properties (wall elasticity and viscosity). IMTc is increased in patients with type 2 DM and other independent risk factors, such as: age, hyperlipidemia and duration of DM. Subjects with DM have shown increased arterial stiffness. Type 2 DM is associated with reductions in FMD (endothelial dysfunction), which has already been reported to be inversely and strongly related to the extent of hyperglycemia. The underlying patho-physiological mechanisms are complex and remain to be fully elucidated. A complete understanding of the association between arterial alterations and early detection, and type 2 DM, may be critical for the primary prevention of DM-related macro-vascular disease. PMID:20879975

Christen, Alejandra I; Armentano, Ricardo L; Miranda, Adrián; Graf, Sebastián; Santana, Daniel B; Zócalo, Yanina; Baglivo, Hugo P; Sánchez, Ramiro A

2010-11-01

334

Pressure-induced phase transitions in lanthanide monoantimonides with a NaCl-type structure  

International Nuclear Information System (INIS)

By use of synchrotron radiation the powder x-ray diffraction of LnSb (Ln=lanthanide) with a NaCl-type structure has systematically been studied up to 40 GPa at room temperature. First-order phase transitions with the crystallographic change occur for LnSb at high pressures. The structure of the high-pressure phases of LnSb is classified into three groups. The lighter LnSb (Ln=La, Ce, Pr, and Nd) have the tetragonal structure (distorted CsCl-type) at high pressures. The high-pressure form of the middle LnSb (Ln=Sm, Gd, and Tb) is unknown. The heavier LnSb (Ln=Dy, Ho, Er, Tm, and Lu) show the typical NaCl-CsCl (B1-B2) transition at high pressures though the same transition is not observed in the heavier LnP and LnAs. The transition pressures of LnSb increase with decreasing lattice constant in the NaCl-type structure and do not depend on the structure of their high-pressure phases. The high-pressure structural behavior of LnSb is discussed.

2001-10-01

335

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

2013-07-26

336

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

UK PubMed Central (United Kingdom)

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.

Cai C; Cai J; Man J; Yang Y; Wang Z; Wei C

2014-01-01

337

Subject reduction in a Curry-style polymorphic type system with a vectorial structure  

CERN Multimedia

The algebraic lambda-calculus [Vau09] and the linear-algebraic lambda-calculus [AD08] extend the lambda-calculus with the possibility of making arbitrary linear combinations of lambda-terms. The two foundational works of [ADC09] and [DCP10] describe type systems for this calculus respectively accounting for scalars and sums. Building on these approaches, we devise a typed algebraic lambda-calculus merging the two approaches while keeping a language featuring local confluence and a weak subject reduction. This gives rise to an original and general type theory where types, in the same way as terms, have a vector space-like structure. The main contribution of this paper is a subject reduction result, a problem renowned to be a delicate matter under the presence of union-like type constructs.

Arrighi, Pablo; Valiron, Benoît

2010-01-01

338

Structure evolution of Cu-Cu type clusters in Cu-In alloy melts  

Energy Technology Data Exchange (ETDEWEB)

The structure of Cu-12at.%In and Cu-23at.%In alloy melts were studied by using a high-temperature X-ray diffractometer. The radial distribution functions (RDF) were obtained, which reflect the structure information of melts in real space. Gaussian decomposition of the RDFs shows the changing behavior of Cu-Cu type clusters in the melts. The interatomic distance and the atom number of the clusters decrease with increasing temperature. The structure evolution and the so-called 'thermal contraction' of clusters in the melts are discussed.

Cheng Sujuan [Mechanical Engineering Department, Shandong University of Technology, Zibo 255000 (China) and Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)]. E-mail: chsj@sdu.edu.cn; Wang Weimin [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Bian Xiufang [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China); Xin Xubo [Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Jinan 250061 (China)

2004-11-01

339

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

Directory of Open Access Journals (Sweden)

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

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

2012-01-01

340

Compounds of AuBe5 type structure in (Zr,Hf)-Cu-In systems  

International Nuclear Information System (INIS)

The crystal structure of the ZrCu5-xInx compound (x = 0.3-1.3), a 0.6955-0.7042 (2) nm (str.type AuBe5, sp.group F43m) is decoded through the powder method (autodiffractometry HZG-4a, CuK?-irradiation)

1997-01-01

 
 
 
 
341

The phosphorous level fine structure in homoepitaxial and polycrystalline n-type CVD diamond  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The application of very sensitive photocurrent-based spectroscopic techniques have led to the detection of new levels for the electronic structure of the phosphorous donor in n-type CVD diamond. By combining quasi-steady-state photocurrent measurements (PC), photothermal ionisation spectroscopy (PTI...

HAENEN, Ken; NESLADEK, Milos; DE SCHEPPER, Luc; Kravets, R; Vanecek, M; Koizumi, S

342

Crystal Structure of Type 2 Isopentenyl Diphosphate Isomerase from Thermus thermophilus in Complex with Inorganic Pyrophosphate.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The N-terminal region is stabilized in the crystal structure of Thermus thermophilus type 2 isopentenyl diphosphate isomerase in complex with inorganic pyrophosphate, providing new insights about the active site and the catalytic mechanism of the enzyme. The PP i moiety is located near the conserved...

de Ruyck, Je?ro?me; Pouyez, Jenny; Rothman, Steven; Poulter, Dale; Wouters, Johan

343

Structure of C-alkylated coals of reduced and low-reduced types  

Energy Technology Data Exchange (ETDEWEB)

The unique four coals from Donetsk basin (Ukraine), paired according rank but of various genetic types, were C-alkylated and characterized by FTIR spectroscopy. This allowed to establish some differences in chemical structure for untreated coals, based on their different reactivity towards alkylation agent. (orig.)

Krzton, A.F. [Inst. of Coal Chemistry, PAS, Gliwice (Poland); Marinov, S.P.; Stefanova, M. [Inst. of Organic Chemistry, BAS, Sofia (Bulgaria); Butuzova, L.; Matsenko, G.P. [Inst. of Physical Organic and Coal Chemistry, NASU, Donetsk (Ukraine)

1997-12-31

344

Regulation of hepatocyte cell cycle progression and differentiation by type I collagen structure.  

UK PubMed Central (United Kingdom)

Cell behavior is strongly influenced by the extracellular matrix (ECM) to which cells adhere. Both chemical determinants within ECM molecules and mechanical properties of the ECM network regulate cellular response, including proliferation, differentiation, and apoptosis. Type I collagen is the most abundant ECM protein in the body with a complex structure that can be altered in vivo by proteolysis, cross-linking, and other processes. Because of collagen's complex and dynamic nature, it is important to define the changes in cell response to different collagen structures and its underlying mechanisms. This chapter reviews current knowledge of potential mechanisms by which type I collagen affects cell behavior, and it presents data that elucidate specific intracellular signaling pathways by which changes in type I collagen structure differentially regulate hepatocyte cell cycle progression and differentiation. A network of polymerized fibrillar type I collagen (collagen gel) induces a highly differentiated but growth-arrested phenotype in primary hepatocytes, whereas a film of monomeric collagen adsorbed to a rigid dish promotes cell cycle progression and dedifferentiation. Studies presented here demonstrate that protein kinase A (PKA) activity is significantly elevated in hepatocytes on type I collagen gel relative to collagen film, and inhibition of this elevated PKA activity can promote hepatocyte cell cycle progression on collagen gel. Additional studies are presented that examine changes in hepatocyte cell cycle progression and differentiation in response to increased rigidity of polymerized collagen gel by fiber cross-linking. Potential mechanisms underlying these cellular responses and their implications are discussed.

Hansen LK; Wilhelm J; Fassett JT

2006-01-01

345

Earthquake-proof support structures for the recycling pump in FBR type reactors  

International Nuclear Information System (INIS)

[en] Purpose: To improve the earthquake proofness of the recycling pump for use in FBR type reactors upon earthquake by reducing the vibration response of the pump. Constitution: The outer casing of a recycle pump suspended into liquid sodium is extended to the portion that penetrates a reactor core support structures. Support structures surrounding the outer side of the recycling pump are disposed with a gap not restraining the free thermal deformations of the recycling pump to the inside of the partition wall structures and the portion of the recycling pump penetrating the reator core support structures, to integrate the support structures with the reactor core support structures. Accordingly, there are no interferences between the recycling pump and the support structures with respect to the thermal deformations that change gradually with time. Upon vibrating under the rapidly changing external forces of earthquakes, however, the pressure resulted to the liquid in the gap due to the vibrations of the recycling pump is transmitted with no escape to the support structures, the recycling pump and the support structures integrally resist the vibrations thereby enabling to reduce the vibrations in the recycling pumps. (Horiuchi, T.)

1982-10-22

346

Comparative analysis of structural properties of the C-type-lectin-like domain (CTLD).  

Science.gov (United States)

The superfamily of proteins containing the C-type-lectin-like domain (CTLD) is a group of abundant extracellular metazoan proteins characterized by evolutionary flexibility and functional versatility. Several CTLDs are also found in parasitic prokaryotes and viruses. The 37 distinct currently available CTLD structures demonstrate significant structural conservation despite low or undetectable sequence similarity. Our aim in this study was to perform an extensive comparative analysis of all available CTLD structures to establish the most conserved structural features of the fold, and to test and extend the early analysis of Drickamer. By implication, these features should be those critical for maintenance of integrity of the fold. By analyzing CTLD structures superimposed by several methods, we have established groups of conserved structural positions involved in fold maintenance but not in ligand binding; these are consistent with the fold's known functional flexibility. In addition to the well-recognized disulfide bridges, groups of conserved residues are involved in hydrophobic interactions stabilizing the core of the fold and the long loop region, and in an alpha2-beta1-beta5 polar interaction. Evaluation of the conclusions of the structure comparison study compared with alignments of all available human, mouse and Caenorhabditis elegans CTLD sequences showed that conservation patterns are preserved throughout the whole CTLD sequence space. Our observations provide an improved understanding of CTLD structure, and will help in identification of new CTLDs and the mechanisms that drive and constrain the coevolution of the structure and function of the fold. PMID:12866057

Zelensky, Alex N; Gready, Jill E

2003-08-15

347

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

2009-01-01

348

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

UK PubMed Central (United Kingdom)

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

Light SH; Krishna SN; Bergan RC; Lavie A; Anderson WF

2013-03-01

349

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-08-15

350

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

International Nuclear Information System (INIS)

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

1992-01-01

351

Vector-type four-quark interaction and its impact on QCD phase structure  

CERN Document Server

Effects of the vector-type four-quark interaction on QCD phase structure are investigated in the imaginary chemical potential region, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model with the extended Z3 symmetry. In the course to this end, we clarify analytically the Roberge-Weiss periodicity and symmetry properties of various quantities under the existence of a vector-type four-quark interaction. In the imaginary chemical potential region, the chiral condensate and the quark number density are sensitive to the strength of the interaction. Based on this result, we propose a possibility to determine the strength of the vector-type interaction, which largely affects QCD phase structure in the real chemical potential region, by comparing the results of lattice simulations and effective model calculations in the imaginary chemical potential region.

Sakai, Yuji; Kouno, Hiroaki; Matsuzaki, Masayuki; Yahiro, Masanobu

2008-01-01

352

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

International Nuclear Information System (INIS)

[en] 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)

2010-01-01

353

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

International Nuclear Information System (INIS)

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

2009-01-01

354

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

UK PubMed Central (United Kingdom)

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.

Kushwaha GS; Yamini S; Kumar M; Sinha M; Kaur P; Sharma S; Singh TP

2013-05-01

355

Structural and thermal equilibrium vacancies in CoTi intermetallic compounds with B2 type structure  

International Nuclear Information System (INIS)

[en] Positron annihilation technique was applied to study vacancies and vacancy-clusters in CoTi intermetallic compounds. Followings were resulted from the experiments. (1) No structural vacancies were at Co-rich side, but the presence of vacancies was found at Ti-rich side. (2) The positron lifetimes of a vacancy at Co-rich and Ti-rich sides were found to be 143.1 and 162.4 ps, respectively. This result indicated that the vacancy site formed at Co-rich side was different from that at Ti-rich side. (3) Vacancies in thermal equilibrium at Co-rich side were formed at very low temperatures about 0.38 TM (melting temperature), which value was quite low compared with that of normal pure metals about 0.6 TM. (4) The formation enthalpy for a vacancy was estimated to be about 0.43 eV, which showed a quite low value compared with that normalized by normal pure metals. (Y. Kazumata)

1998-01-01

356

Structural and thermal equilibrium vacancies in CoTi intermetallic compounds with B2 type structure  

Energy Technology Data Exchange (ETDEWEB)

Positron annihilation technique was applied to study vacancies and vacancy-clusters in CoTi intermetallic compounds. Followings were resulted from the experiments. (1) No structural vacancies were at Co-rich side, but the presence of vacancies was found at Ti-rich side. (2) The positron lifetimes of a vacancy at Co-rich and Ti-rich sides were found to be 143.1 and 162.4 ps, respectively. This result indicated that the vacancy site formed at Co-rich side was different from that at Ti-rich side. (3) Vacancies in thermal equilibrium at Co-rich side were formed at very low temperatures about 0.38 T{sub M} (melting temperature), which value was quite low compared with that of normal pure metals about 0.6 T{sub M}. (4) The formation enthalpy for a vacancy was estimated to be about 0.43 eV, which showed a quite low value compared with that normalized by normal pure metals. (Y. Kazumata)

Misumi, K.; Aono, S.; Araki, Hideki; Shirai, Yasuharu [Osaka Univ. (Japan)

1998-09-01

357

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1994-05-01

358

Chromosomal localization and structure of the human type II IMP dehydrogenase gene (IMPDH2)  

Energy Technology Data Exchange (ETDEWEB)

The authors determined the chromosomal localization and structure of the gene encoding human type II inosine 5[prime]-monophosphate dehydrogenase (IMPDH, EC 1.1.1.205), an enzyme associated with cellular proliferation, malignant transformation, and differentiation. Using polymerase chain reaction (PCR) primers specific for type II IMPDH, they screened a panel of human-Chinese hamster cell somatic hybrids and a separate deletion panel of chromosome 3 hybrids and localized the gene to 3p21.2 [yields] p24.2. Two overlapping yeast artificial chromosome clones containing the full gene for type II IMPDH (IMPDH2) were isolated, and a physical map of 117 kb of human genomic DNA in this region of chromosome 3 was constructed. The gene for type II IMPDH was localized and oriented on this map and found to span no more than 12.5 kb. 14 refs., 2 figs., 1 tab.

Glesne, D.; Huberman, E. (Univ. of Chicago, IL (United States) Argonne National Lab., IL (United States)); Collart, F. (Argonne National Lab., IL (United States)); Varkony, T.; Drabkin, H. (Univ. of Colorado, Denver (United States))

1993-04-01

359

High-pressure structural investigation of several zircon-type orthovanadates  

CERN Multimedia

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

360

The structure of the R^8 term in type IIB string theory  

CERN Document Server

Based on the structure of the on-shell linearized superspace of type IIB supergravity, we argue that there is a non--BPS 16 derivative interaction in the effective action of type IIB string theory of the form (t_8 t_8 R^4)^2, which we call the R^8 interaction. It lies in the same supermultiplet as the G^8 R^4 interaction. Using the KLT relation, we analyse the structure of the tree level eight graviton scattering amplitude in the type IIB theory, which leads to the R^8 interaction at the linearized level. This involves an analysis of color ordered multi-gluon disc amplitudes in the type I theory, which shows an intricate pole structure and transcendentality consistent with various other interactions. Considerations of S-duality show that the R^8 interaction receives non-analytic contributions in the string coupling at one and two loops. Apart from receiving perturbative contributions, we show that the R^8 interaction receives a non-vanishing contribution in the one D-instanton-anti-instanton background at lea...

Basu, Anirban

2013-01-01

 
 
 
 
361

Structural studies of an A2-type modular polyketide synthase ketoreductase reveal features controlling ?-substituent stereochemistry.  

UK PubMed Central (United Kingdom)

Modular polyketide synthase ketoreductases often set two stereocenters when reducing intermediates in the biosynthesis of a complex polyketide. Here we report the 2.60 Å-resolution structure of an A2-type ketoreductase from the eleventh module of the amphotericin polyketide synthase that sets a combination of L-?-methyl and L-?-hydroxyl stereochemistries and represents the final catalytically-competent ketoreductase type to be structurally elucidated. Through structure-guided mutagenesis a double mutant of an A1-type ketoreductase was generated that functions as an A2-type ketoreductase on a diketide substrate analog, setting an ?-alkyl substituent in an L- orientation rather than in the D- orientation set by the unmutated ketoreductase. When the activity of the double-mutant was examined in the context of an engineered triketide lactone synthase, the anticipated triketide lactone was not produced even though the ketoreductase-containing module still reduced the diketide substrate analog as expected. These findings suggest that re-engineered ketoreductases may be catalytically outcompeted within engineered polyketide synthase assembly lines.

Zheng J; Piasecki SK; Keatinge-Clay AT

2013-06-01

362

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

UK PubMed Central (United Kingdom)

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.

Fatmawati S; Kondo R; Shimizu K

2013-11-01

363

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

2013-09-05

364

Structural analysis of protein-protein interactions in type I polyketide synthases.  

UK PubMed Central (United Kingdom)

Polyketide synthases (PKSs) are responsible for synthesizing a myriad of natural products with agricultural, medicinal relevance. The PKSs consist of multiple functional domains of which each can catalyze a specified chemical reaction leading to the synthesis of polyketides. Biochemical studies showed that protein-substrate and protein-protein interactions play crucial roles in these complex regio-/stereo-selective biochemical processes. Recent developments on X-ray crystallography and protein NMR techniques have allowed us to understand the biosynthetic mechanism of these enzymes from their structures. These structural studies have facilitated the elucidation of the sequence-function relationship of PKSs and will ultimately contribute to the prediction of product structure. This review will focus on the current knowledge of type I PKS structures and the protein-protein interactions in this system.

Xu W; Qiao K; Tang Y

2013-03-01

365

Azo structure carboxylic amide type dyes for polylactic acid fiber dyeing and preparation method thereof  

UK PubMed Central (United Kingdom)

The invention discloses a carboxamide type dye which has an azo structure and is used for dyeing polylactic acid fibre. The molecular structure contains a carboxamide group the general structural formula of the dye is shown above. In the formula, D is a chromogen with the azo structure m is 1 or 2 X is H or n-CnH2n+1 Y is H, n-CnH2n+1, C6H12 or C6H6 and in the n-CnH2n+1, n meets the following condition: n is more than or equal to 1 and less than or equal to 18,,and n is an integer. The invention simultaneously discloses a method for preparing the dye. The dye is used to improve the rate of dye-uptake and color fastness on the PLA fibre.

ZHIHUA CUI; WEIGUO CHEN; JINHUAN ZHENG; ENLING HU; JIANHUA XU

366

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

International Nuclear Information System (INIS)

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

2007-09-01

367

Habitat Evaluation on Scour Hole Downflow Low Drop Structure Types Using Large-Scale Experiment  

Directory of Open Access Journals (Sweden)

Full Text Available This study sought to review whether large-scale experimentation can apply to actual rivers concerning the effect of topographical change by scour in the downstream area of natural-type low drop structures on the fish habitat. The large-scale applicability experiment performed in this study installed low drop structures as the study object within the experiment channel and precisely surveyed topography in the downstream area of drop structures along with the hydraulic amount including water level and flow velocity under certain flow conditions. Based on topographical data acquired through the survey after the experiment ended, this study reviewed the change of suitability index and difference of weighted usable area by performing 2D habitat simulation. Ultimately, through the habitat simulation results in cases of considering and not considering scour in the downstream area of drop structures, this study analyzed the effects of topographical change in actual rivers on the habitat.

Joongu Kang; Changsung Kim; Sanghwa Jung; Hongkoo Yeo

2012-01-01

368

Structural Basis for Substrate Binding and the Catalytic Mechanism of Type III Pantothenate Kinase  

Energy Technology Data Exchange (ETDEWEB)

Pantothenate kinase (PanK) catalyzes the first step of the universal five-step coenzyme A (CoA) biosynthetic pathway. The recently characterized type III PanK (PanK-III, encoded by the coaX gene) is distinct in sequence, structure and enzymatic properties from both the long-known bacterial type I PanK (PanK-I, exemplified by the Escherichia coli CoaA protein) and the predominantly eukaryotic type II PanK (PanK-II). PanK-III enzymes have an unusually high K{sub m} for ATP, are resistant to feedback inhibition by CoA, and are unable to utilize the N-alkylpantothenamide family of pantothenate analogues as alternative substrates, thus making type III PanK ineffective in generating CoA analogues as antimetabolites in vivo. Previously, we reported the crystal structure of the PanK-III from Thermotoga maritima and identified it as a member of the 'acetate and sugar kinase/heat shock protein 70/actin' (ASKHA) superfamily. Here we report the crystal structures of the same PanK-III in complex with one of its substrates (pantothenate), its product (phosphopantothenate) as well as a ternary complex structure of PanK-III with pantothenate and ADP. These results are combined with isothermal titration calorimetry experiments to present a detailed structural and thermodynamic characterization of the interactions between PanK-III and its substrates ATP and pantothenate. Comparison of substrate binding and catalytic sites of PanK-III with that of eukaryotic PanK-II revealed drastic differences in the binding modes for both ATP and pantothenate substrates, and suggests that these differences may be exploited in the development of new inhibitors specifically targeting PanK-III.

Yang, Kun; Strauss, Erick; Huerta, Carlos; Zhang, Hong (Stellenbosch); (UTSMC)

2008-07-15

369

Structural basis for substrate binding and the catalytic mechanism of type III pantothenate kinase.  

Science.gov (United States)

Pantothenate kinase (PanK) catalyzes the first step of the universal five-step coenzyme A (CoA) biosynthetic pathway. The recently characterized type III PanK (PanK-III, encoded by the coaX gene) is distinct in sequence, structure and enzymatic properties from both the long-known bacterial type I PanK (PanK-I, exemplified by the Escherichia coli CoaA protein) and the predominantly eukaryotic type II PanK (PanK-II). PanK-III enzymes have an unusually high Km for ATP, are resistant to feedback inhibition by CoA, and are unable to utilize the N-alkylpantothenamide family of pantothenate analogues as alternative substrates, thus making type III PanK ineffective in generating CoA analogues as antimetabolites in vivo. Previously, we reported the crystal structure of the PanK-III from Thermotoga maritima and identified it as a member of the "acetate and sugar kinase/heat shock protein 70/actin" (ASKHA) superfamily. Here we report the crystal structures of the same PanK-III in complex with one of its substrates (pantothenate), its product (phosphopantothenate) as well as a ternary complex structure of PanK-III with pantothenate and ADP. These results are combined with isothermal titration calorimetry experiments to present a detailed structural and thermodynamic characterization of the interactions between PanK-III and its substrates ATP and pantothenate. Comparison of substrate binding and catalytic sites of PanK-III with that of eukaryotic PanK-II revealed drastic differences in the binding modes for both ATP and pantothenate substrates, and suggests that these differences may be exploited in the development of new inhibitors specifically targeting PanK-III. PMID:18186650

Yang, Kun; Strauss, Erick; Huerta, Carlos; Zhang, Hong

2008-01-11

370

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

International Nuclear Information System (INIS)

[en] Graphical abstract: A perspective view of the Na2Ni2Fe(PO4)3 structure along the [0 0 1] direction. Both compounds seem to exibit antiferromagnetic interactions between magnetic entities at low temperature. Display Omitted Research highlights: ? Nasicon and Alluaudite compounds, Iron(III)-based phosphates, Crystal structures of Na4NiFe(PO4)3 and Na2Ni2Fe(PO4)3. ? Magnetism behaviours of Na4NiFe(PO4)3 and Na2Ni2Fe(PO4)3. ? Antiferromagnetism interactions. ? Mossbauer spectroscopy. - Abstract: Crystal structures from two new phosphates Na4NiFe(PO4)3 (I) and Na2Ni2Fe(PO4)3 (II) have been determined by single crystal X-ray diffraction analysis. Compound (I) crystallizes in a rhombohedral system (S. G: R-3c, Z = 6, a = 8.7350(9) A, c = 21.643(4) A, R1 = 0.041, wR2=0.120). Compound (II) crystallizes in a monoclinic system (S. G: C2/c, Z = 4, a = 11.729(7) A, b = 12.433(5) A, c = 6.431(2) A, ? = 113.66(4)o, R1 = 0.043, wR2=0.111). The three-dimensional structure of (I) is closely related to the Nasicon structural type, consisting of corner sharing [(Ni/Fe)O6] octahedra and [PO4] tetrahedra forming [NiFe(PO4)3]4+ units which align in chains along the c-axis. The Na+ cations fill up trigonal antiprismatic sites within these chains. The crystal structure of (II) belongs to the alluaudite type. Its open framework results from [Ni2O10] units of edge-sharing [NiO6] octahedra, which alternate with [FeO6] octahedra that form infinite chains. Coordination of these chains yields two distinct tunnels in which site Na+. The magnetization data of compound (I) reveal antiferromagnetic (AFM) interactions by the onset of deviations from a Curie-Weiss behaviour at low temperature as confirmed by Moessbauer measurements performed at 4.2 K. The corresponding temperature dependence of the reciprocal susceptibility ?-1 follows a typical Curie-Weiss behaviour for T > 105 K. A canted AFM state is proposed for compound (II) below 46 K with a field-induced magnetic transition at H ? 19 kOe, revealed in the hysteresis loop measured at 5 K. This transition is most probably associated with a spin-flop transition.

2011-01-28

371

Structural and physical properties diversity of new CaCu5-type related europium platinum borides.  

UK PubMed Central (United Kingdom)

Three novel europium platinum borides have been synthesized by arc melting of constituent elements and subsequent annealing. They were characterized by X-ray powder and single-crystal diffraction: EuPt4B, CeCo4B type, P6/mmm, a = 0.56167(2) nm, c = 0.74399(3) nm; Eu3Pt7B2, Ca3Al7Cu2 type as an ordered variant of PuNi3, R3m, a = 0.55477(2) nm, c = 2.2896(1) nm; and Eu5Pt18B(6-x), a new unique structure type, Fmmm, a = 0.55813(3) nm, b = 0.95476(5) nm, c = 3.51578(2) nm. These compounds belong to the CaCu5 family of structures, revealing a stacking sequence of CaCu5-type slabs with different structural units: CaCu5 and CeCo3B2 type in EuPt4B; CeCo3B2 and Laves MgCu2 type in Eu3Pt7B2; and CaCu5-, CeCo3B2-, and site-exchange ThCr2Si2-type slabs in Eu5Pt18B(6-x). The striking motif in the Eu5Pt18B(6-x) structure is the boron-centered Pt tetrahedron [BPt4], which build chains running along the a axis and plays a decisive role in the structure arrangement by linking the terminal fragments of repeating blocks of fused Eu polyhedra. Physical properties of two compounds, EuPt4B and Eu3Pt7B2, were studied. Both compounds were found to order magnetically at 36 and 57 K, respectively. For EuPt4B a mixed-valence state of the Eu atom was confirmed via magnetic and specific heat measurements. Moreover, the Sommerfeld value of the specific heat of Eu3Pt7B2 was found to be extraordinarily large, on the order of 0.2 J/mol?K(2).

Salamakha L; Bauer E; Hilscher G; Michor H; Sologub O; Rogl P; Giester G

2013-04-01

372

Synthesis and crystal structure of three silver indium double phosphates  

Science.gov (United States)

Three new silver indium double phosphates Ag3In(PO4)2 (I), ?-(II) and ?-Ag3In2(PO4)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-3c, 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 Ag3In(PO4)2 is related to the sodium chromate structure type and is isotypic to ?-Na3In(PO4)2. The polymorphous modifications of ?- and ?-Ag3In2(PO4)3 are isostructural to sodium analogs (?- and ?-Na3In2(PO4)3) and are related to alluaudite (II) and NASICON (III) structure types. Compounds I and II are not stable at temperature above 850 °C. Ag3In(PO4)2 is decomposed providing silver orthophosphate Ag3PO4 and ?-Ag3In2(PO4)2. ?-Ag3In2(PO4)3 is transformed to ?-Ag3In2(PO4)3.

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

2006-12-01

373

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

374

Heritable effect of the initial structure of powder particles on mechanical properties of structural 30KHN3MF type steel  

International Nuclear Information System (INIS)

The effect of granule metallurgy on properties of structural 30KhN3MF type steel sheet blanks was studied by the methods of light microscopy, X-ray spectrum microanalysis, X-ray diffraction analysis, fractography using scanning electron microscope and by mechanical tensile and impact tests of samples with Charpy and Mesnager notches. It is shown that production of the powder by the method of liquid metal jet spraying by nitrogen results in formation of oxide films on the surface of powder particles. These oxide films lead to disturbance in the material homogeneity and affect negatively the mechanical behaviour of the compacts

1980-01-01

375

Plate-like structure formation in single crystals of magnetic alloy type YuNDKT  

International Nuclear Information System (INIS)

[en] Specific features of structure and dendritic-cellular segregation were studied in ALNICO alloy single crystals grown by directional crystallization technique. X-ray diffraction studied showed that castings of YuNDK35T5+0.2%S alloy consisted of ?'- and ?-phases and had lamellar structure. Crystallization was revealed to proceed with formation of eutectics. Sulfur alloying promoted a decrease of segregation in dendritic calls of ?-phase and so enhanced magnetic properties of the alloy. Results of microscopical examination and X-ray analysis of ALNICO type alloys with sulfur addition are presented. 14 refs., 5 figs., 2 tabs

1994-01-01

376

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

Science.gov (United States)

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

Ahmadi, A.; Keramat, A.

2010-10-01

377

Seismic isolation structure for pool-type LMFBR - isolation building with vertically isolated floor for NSSS  

International Nuclear Information System (INIS)

[en] The NSSS isolation floor vibration characteristics were made clear. Especially, the side support bearing (rubber bearing) is effective for horizontal floor motion restraint and rocking motion control. Seismic isolation effects for responses of the reactor components can be sufficiently expected, using the vertical seismic isolation floor. From the analytical and experimental studies, the following has been concluded: (1) Seismic isolation structure, which is suitable for large pool-type LMFBR, were proposed. (2) Seismic response characteristics of the seismic isolation structure were investigated. It was made clear that the proposed seismic isolation (Combination of the isolated building and the isolated NSSS floor) was effective. (orig./HP)

1987-01-01

378

The structure and properties of different types of starch exposed to UV radiation: A comparative study.  

UK PubMed Central (United Kingdom)

The effect of UV-irradiation on four different types of native starch (corn, waxy corn, wheat and potato) have been investigated. Although the changes in the chemical structure of starch specimens were small, indicating good photostability, the samples lost adsorbed water and their crystallinity degree decreased after irradiation. Moreover, a drop in average molecular weight occurred in samples (with the exception of potato starch) as a result of main chain scission. The variations in the properties of investigated specimens of various origin were related to the differences in their structure and macromolecular arrangement. The lowest photostability among the four starches was exhibited by potato starch.

Bajer D; Kaczmarek H; Bajer K

2013-10-01

379

Flux Vacua Attractors in Type II on SU(3)xSU(3) Structure  

CERN Multimedia

We summarize and extend our work on flux vacua attractors in generalized compactifications. After reviewing the attractor equations for the heterotic string on SU(3) structure manifolds, we study attractors for N=1 vacua in type IIA/B on SU(3)xSU(3) structure spaces. In the case of vanishing RR flux, we find attractor equations that encode Minkowski vacua only (and which correct a previous normalization error). In addition to our previous considerations, here we also discuss the case of nonzero RR flux and the possibility of attractors for AdS vacua.

Anguelova, Lilia

2009-01-01

380

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

International Nuclear Information System (INIS)

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

2000-01-01

 
 
 
 
381

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

International Nuclear Information System (INIS)

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

1999-01-01

382

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

International Nuclear Information System (INIS)

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

2001-01-01

383

The structure and properties of different types of starch exposed to UV radiation: A comparative study.  

Science.gov (United States)

The effect of UV-irradiation on four different types of native starch (corn, waxy corn, wheat and potato) have been investigated. Although the changes in the chemical structure of starch specimens were small, indicating good photostability, the samples lost adsorbed water and their crystallinity degree decreased after irradiation. Moreover, a drop in average molecular weight occurred in samples (with the exception of potato starch) as a result of main chain scission. The variations in the properties of investigated specimens of various origin were related to the differences in their structure and macromolecular arrangement. The lowest photostability among the four starches was exhibited by potato starch. PMID:23987371

Bajer, Dagmara; Kaczmarek, Halina; Bajer, Krzysztof

2013-06-14

384

Crystal structures and luminescent properties of lanthanide nitrate coordination polymers with structurally related amide type bridging podands  

International Nuclear Information System (INIS)

A one-dimensional linear chain coordination polymer [ErLI(NO3)3(CH3CO2Et)]n (LI=1,2-bis{[(2'-furfurylaminoformyl)phenoxyl]methyl}benzene) and a one-dimensional zig-zag coordination polymer {[TbLII(NO3)3(H2O)].(H2O)}n (LII=1,2-bis{[2'-(2-pyridylmethylaminoformyl)phenoxyl]methyl}benzene) were assembled by two structurally related bridging podands LI and LII which have uniform skeleton and different terminal groups. In {[TbLII(NO3)3(H2O)].(H2O)}n, the neutral chains were linked by the hydrogen bonding interactions between the free and coordinated water molecules from two different directions to interpenetrate into a 3D supramolecular structure. At the same time, the luminescent properties of the solid Tb(III) nitrate complexes of these podands were investigated at room temperature. The lowest triplet state energy levels T1 of the podands LI and LII indicate that the triplet state energy levels of the antennae are both above the lowest excited resonance level of 5D4 of Tb3+ ion. Thus the absorbed energy could be transferred from ligands to the central Tb3+ ions. And the influence of the hydrogen bonding on the luminescence efficiencies of the coordination polymers was also discussed. -- Graphical Abstract: Two one-dimensional lanthanide coordination polymers were assembled by two structurally related bridging podands, and the effects of the structures on luminescent properties of the solid Tb(III) nitrate complexes were investigated. Display Omitted Research Highlights: ? Two structurally related amide type bridging ligands were designed and synthesized. ? Two one dimensional lanthanide nitrate coordination polymers were obtained. ? The structure effects on luminescent properties of the terbium complexes were discussed.

2011-01-01

385

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

International Nuclear Information System (INIS)

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

2006-01-01

386

Structures and free energy landscapes of the wild-type and A30P mutant-type ?-synuclein proteins with dynamics.  

UK PubMed Central (United Kingdom)

The genetic missense A30P mutation of the wild-type ?-synuclein protein results in the replacement of the 30th amino acid residue from alanine (Ala) to proline (Pro) and was initially found in the members of a German family who developed Parkinson's disease. Even though the structures of these proteins have been measured before, detailed understanding about the structures and their relationships with free energy landscapes is lacking, which is of interest to provide insights into the pathogenic mechanism of Parkinson's disease. We report the secondary and tertiary structures and conformational free energy landscapes of the wild-type and A30P mutant-type ?-synuclein proteins in an aqueous solution environment via extensive parallel tempering molecular dynamics simulations along with thermodynamic calculations. In addition, we present the residual secondary structure component transition stabilities at the atomic level with dynamics in terms of free energy change calculations using a new strategy that we reported most recently. Our studies yield new interesting results; for instance, we find that the A30P mutation has local as well as long-range effects on the structural properties of the wild-type ?-synuclein protein. The helical content at Ala18-Gly31 is less prominent in comparison to the wild-type ?-synuclein protein. The ?-sheet structure abundance decreases in the N-terminal region upon A30P mutation of the wild-type ?-synuclein, whereas the NAC and C-terminal regions possess larger tendencies for ?-sheet structure formation. Long-range intramolecular protein interactions are less abundant upon A30P mutation, especially between the NAC and C-terminal regions, which is linked to the less compact and less stable structures of the A30P mutant-type rather than the wild-type ?-synuclein protein. Results including the usage of our new strategy for secondary structure transition stabilities show that the A30P mutant-type ?-synuclein tendency toward aggregation is higher than the wild-type ?-synuclein but we also find that the C-terminal and NAC regions of the A30P mutant-type ?-synuclein are reactive toward fibrillzation and aggregation based on atomic level studies with dynamics in an aqueous solution environment. Therefore, we propose that small molecules or drugs blocking the specific residues, which we report herein, located in the NAC- and C-terminal regions of the A30P mutant-type ?-synuclein protein might help to reduce the toxicity of the A30P mutant-type ?-synuclein protein.

Wise-Scira O; Aloglu AK; Dunn A; Sakallioglu IT; Coskuner O

2013-03-01

387

Study on vegetation community's structure of degraded grassland of noxious and miscellaneous grass type  

UK PubMed Central (United Kingdom)

On the degraded grassland of noxious and miscellaneous grass type, according to its different degree of the degradation and the distribution of the Stellera chaejasme L., the main noxious grass on this grassland type, the grassland can be plotted to five types: type 1, with Stellera chamaejasme density range of 0--19%; type 2, with Stellera chamaejasme density range of 20%--39%; type 3, with Stellera chamaejasme density range of 40%--59%; type 4, with Stellera chamaejasme density range of 60%--79%; type 5, with Stellera chamaejasme density range of 80%--95%. After research on the vegetation's constitution and function and the degradation regulation of the five types, the result shows taht on the mountain grassland with S.Krylovii Roshev and A. cristatum L. Gaertn as the main advantage grasses, vegetation structure has relative stability. But due to herds increasing, the competition among different kind plants changes. As a result, Stellera chamaejasme L., with its special competition ability, its numbers and effects increasing step by step in the vegetation community. During the processes of the Stellera chamaejasme L increasing, the output over the ground and the density of the eatable grass such as S.Krylovii Roshev and A.cristatum L. Gaerth decreased. Following with the increasing of the Stellera chamaejasme L, the variety index Shannon-Wiener and the equality index Pielou are all changed from low to high and then to low again, but the superiority index Simpson takes on a opposite trend. At last the advanced grass of the vegetation community has been changed. Stellera chamaejasme L. changed from minor to major. So the natural grassland has been degraded by the Stellera chamaejasme L. On the basis of the above research, we have also brought forward some countermeasures to resume and enhance the production of such degraded grassland.

Zhao Chengzhang; Pan Shengyue; Yin Cuiqin; He Xuebin

2004-01-01

388

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

Directory of Open Access Journals (Sweden)

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

O.G.Vlokh

2000-01-01

389

Interface influence on structural properties of InAs/GaSb type-II superlattices  

Directory of Open Access Journals (Sweden)

Full Text Available Theoretical studies of interface impact on structural properties of InAs/GaSb type-II superlattices were carried out. Multilayer structures used for mid-infrared detection were considered. The superlattices examined consisted of 190 pairs of 9 monolayers (MLs) of InAs and 10 MLs of GaSb. Both types of interfaces, i.e., “GaAs-like” as well as “InSb-like”, were analyzed. The simulations were performed using dynamical theory of diffraction for different thicknesses of interface layers. The lattice mismatch was extracted from X-ray diffraction profiles. The analysis performed shows that the strain-balanced InAs/GaSb superlattice can be optimized by using thin InSb-like or GaAs-like interface layers simultaneously.

Justyna Kubacka-Traczyk; Iwona Sankowska; Janusz Kaniewski

2009-01-01

390

Influence of different fertilizer types of zucchini (Cucurbita pepo) on the structure of nematode communities.  

UK PubMed Central (United Kingdom)

Increasing efficiency of production of vegetable crops is directly related to search for appropriate solution to increase their productivity. Organic amendments have been used for centuries to improve soil fertility and crop yield. Our study suggests that organic amendments can also be used as nematicidal agents. The survey was conducted on Experimental field of Department Horticulture at Agricultural University of Plovdiv, Bulgaria in 2009 on nematode infested sites. Combination with two types of fertilizers was used to investigate their effects on the community of soil nematodes. Characterization and comparative analysis among treatments of soil nematode community structure based on different ecological measures such as total nematode abundance, number of genera, trophic diversity and etc., was made. Changes in the composition and structure of nematode community as result of different fertilizer types were assessed.

Haytova D; Bileva T

2011-01-01

391

Mechanical design of steam turbine moving blades with snubber type blade connection structure  

Energy Technology Data Exchange (ETDEWEB)

Different kinds of blades have been developed to improve the reliability of stages near the region of transition from dry steam to wet steam in turbines. For example, the next to last (L-1) stage of a fossil turbine is at or just downstream of the Wilson line, and has been especially susceptible to corrosion-induced failures (Warner, 1985). The new blades were designed with snubber type blade connection structures and outside dovetail root attachment. A snubber type blade connection structure is effective in reducing dynamic stresses on the blades (Neumann,1989). Dynamic stress on the blade-wheel dovetail attachment is also reduced. Consequently it is advantageous in avoiding failures such as corrosion fatigue or stress-corrosion cracking, especially in corrosive environments. This paper describes the design procedure of a snubber configuration favorable from the points of view of machining and assembly. The results of some verification tests are also included.

Suzuki, T.; Kaneko, J.; Aoyama, M. [Toshiba Corp., Yokohama (Japan). Keihin Product Operation

1995-12-31

392

Temperature-dependent Debye-Waller factors for semiconductors with the wurtzite-type structure.  

UK PubMed Central (United Kingdom)

We computed Debye-Waller factors in the temperature range from 0.1 to 1000 K for AlN, GaN, InN, ZnO and CdO with the wurtzite-type structure. The Debye-Waller factors were derived from phonon densities of states obtained from Hellmann-Feynman forces computed within the density-functional-theory formalism. The temperature dependences of the Debye-Waller factors were fitted and fit parameters are given.

Schowalter M; Rosenauer A; Titantah JT; Lamoen D

2009-05-01

393

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

International Nuclear Information System (INIS)

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

2009-07-20

394

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

395

Preliminary structural analysis on the sealed basket type instrumented capsule for fuel irradiation tests in HANARO  

International Nuclear Information System (INIS)

[en] To develop the sealed basket type instrumented capsule to be used for the irradiation test of various nuclear fuels, it is necessary to ensure the compatibility of the capsule with HANARO and the structural integrity of the capsule. The dimensions of the sealed basket type instrumented capsule were determined on the basis of the pressure drop criteria in OR test hole of HANARO(mass flow rate m200kPa). From the buckling stability analysis for this capsule, the critical buckling load Pcr was 6.8kN. The vertical impact stress of the capsule under unit impact load was evaluated by the transient analysis, and the maximum vertical impact load calculated from the impact stress and the allowable stress was 60.4kN. Under the loading of the calculated Pcr, the maximum vertical impact stress was 19.3MPa. The structural integrity of the capsule under a horizontal impact loading was also examined. The mechanical stresses occurred by the pressure difference at the inner and outer surface of outer tube and by the coolant pressure at the surface of outer tube were 3.6MPa and 60.2MPa, respectively. These stress values were lower than the allowable stress in each case. Therefore, it was ensured that the sealed basket type instrumented capsule for the irradiation test of various nuclear fuels met the criteria on the structural integrity during installing and testing in HANARO

2002-01-01

396

Structural comparison of the transport units of type V secretion systems.  

Science.gov (United States)

Abstract Pathogenic gram-negative bacteria have evolved several secretion mechanisms to translocate adhesins, enzymes, toxins, and other virulence factors across the inner and outer membranes. Currently, eight different secretion systems, type I-type VIII (T1SS-T8SS) plus the chaperone-usher (CU) pathway, have been identified, which act in one-step or two-step mechanisms to traverse both membrane barriers. The type V secretion system (T5SS) is dependent first on the Sec translocon within the inner membrane. The periplasmic intermediates are then secreted through aqueous pores formed by ?-barrels in the outer membrane. Until now, transport across the outer membrane has not been understood on a molecular level. With respect to special characteristics revealed by crystal structure analysis, bioinformatic and biochemical data, five subgroups of T5SS were defined. Here, we compare the transport moieties of members of four subgroups based on X-ray crystal structures. For the fifth subgroup, which was identified only recently, no structures have thus far been reported. We also discuss different models for the translocation process across the outer membrane with respect to recent findings. PMID:23929883

Gawarzewski, Iris; Smits, Sander H J; Schmitt, Lutz; Jose, Joachim

2013-11-01

397

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

398

FLUIDS, PLASMAS AND ELECTRIC DISCHARGES: Comparative research on three types of coaxial slow wave structures  

Science.gov (United States)

This paper studies three types of coaxial slow wave structures (SWSs): (1) with ripples on both the inner and outer conductors; (2) with ripples on the outer conductor and smooth on the inner one; and (3) with ripples on the inner conductor and smooth on the outer one. The frequencies, coupling impedances, time growth rates and beam-wave interaction efficiencies of the three types of coaxial SWSs are obtained by theoretical analysis. Moreover, the relativistic Cerenkov generators (RCGs) with the three types of coaxial SWSs are simulated with a fully electromagnetic particle-in-cell code, and the results verify the theoretical analysis. It is proved that the RCG with double-rippled coaxial SWS has the highest conversion efficiency and the shortest starting time.

Xiao, Ren-Zhen; Liu, Guo-Zhi; Chen, Chang-hua

2008-10-01

399

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

UK PubMed Central (United Kingdom)

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

Furukawa A; Kamishikiryo J; Mori D; Toyonaga K; Okabe Y; Toji A; Kanda R; Miyake Y; Ose T; Yamasaki S; Maenaka K

2013-10-01

400

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

 
 
 
 
401

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

UK PubMed Central (United Kingdom)

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

Kato T; Kato Z; Kuratsubo I; Tanaka N; Ishigami T; Kajihara J; Sukegawa-Hayasaka K; Orii K; Isogai K; Fukao T; Shimozawa N; Orii T; Kondo N; Suzuki Y

2005-01-01

402

On the structural basis and design guidelines for type II topoisomerase-targeting anticancer drugs.  

UK PubMed Central (United Kingdom)

Type II topoisomerases (Top2s) alter DNA topology via the formation of an enzyme-DNA adduct termed cleavage complex, which harbors a transient double-strand break in one DNA to allow the passage of another. Agents targeting human Top2s are clinically active anticancer drugs whose trapping of Top2-mediated DNA breakage effectively induces genome fragmentation and cell death. To understand the structural basis of this drug action, we previously determined the structure of human Top2 ?-isoform forming a cleavage complex with the drug etoposide and DNA, and described the insertion of drug into DNA cleavage site and drug-induced decoupling of catalytic groups. By developing a post-crystallization drug replacement procedure that simplifies structural characterization of drug-stabilized cleavage complexes, we have extended the analysis toward other structurally distinct drugs, m-AMSA and mitoxantrone. Besides the expected drug intercalation, a switch in ribose puckering in the 3'-nucleotide of the cleavage site was robustly observed in the new structures, representing a new mechanism for trapping the Top2 cleavage complex. Analysis of drug-binding modes and the conformational landscapes of the drug-binding pockets provide rationalization of the drugs' structural-activity relationships and explain why Top2 mutants exhibit differential effects toward each drug. Drug design guidelines were proposed to facilitate the development of isoform-specific Top2-targeting anticancer agents.

Wu CC; Li YC; Wang YR; Li TK; Chan NL

2013-09-01

403

Distinct Structural Elements Dictate the Specificity of the Type III Pentaketide Synthase from Neurospora crassa  

Energy Technology Data Exchange (ETDEWEB)

The fungal type III polyketide synthase 2'-oxoalkylresorcyclic acid synthase (ORAS) primes with a range of acyl-Coenzyme A thioesters (C{sub 4}--C{sub 20}) and extends using malonyl-Coenzyme A to produce pyrones, resorcinols, and resorcylic acids. To gain insight into this unusual substrate specificity and product profile, we have determined the crystal structures of ORAS to 1.75 {angstrom} resolution, the Phe-252{yields}Gly site-directed mutant to 2.1 {angstrom} resolution, and a binary conplex of ORAS with eicosanoic acid to 2.0 {angstrom} resolution. The structures reveal a distinct rearrangement of structural elements near the active site that allows accomodation of long-chain fatty acid esters and a reorientation of the gating mechanism that controls cyclization and polyketide chain length. The roles of these structural elements are further elucidated by characterization of various structure-based site-directed variants. These studies establish an unexpected plasticity to the PKS fold, unanticipated from structural studies of other members of this enzyme family.

Rubin-Pitel, Sheryl B.; Zhang, Houjin; Vu, Trang; Brunzelle, Joseph S.; Zhao, Huimin; Nair, Satish K. (UIUC); (NWU)

2009-01-15

404

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

2013-02-07

405

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.

2006-01-05

406

New structure type in the mixed-valent compound YbCu4Ga8.  

UK PubMed Central (United Kingdom)

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.

Subbarao U; Gutmann MJ; Peter SC

2013-02-01

407

Rh3B2-x, new structure type of binary borides with triclinic symmetry  

International Nuclear Information System (INIS)

New binary compound Rh3B2-x, x=0.167 crystallizing with its own structure type has been observed from the as cast alloys. The compound has a limited thermal stability range: it was found to decompose after annealing at 800oC for 20 days. The crystal structure was investigated by X-ray diffraction from two single crystals using different techniques: CAD-4 automatic diffractometer, a=5.470(2), b=6.816(3), c=9.068(4), ?=110.74(3), ?=94.81(3), ?=90.44(2), 107 refined parameters, R1=0.0418, wR2=0.1087 for 1223 reflections with I>2?(Io), and BRUKER SMART AXS, a=5.483(4), b=6.818(6), c=9.072 (7), a=110.78(1), b=94.73(1), g=90.46(1), 107 refined parameters, R1=0.0401, wR2=0.0959 for 943 reflections with I>2?(Io). The Rh3B2-x, structure (space group P1-bar , Pearson symbol aP30-1) is the first representative of structures with triclinic symmetry among binary borides and contains three different types of boron-boron aggregation: isolated boron atoms, B-B pairs and B6 chain fragments

2004-01-01

408

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

1987-07-02

409

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

Energy Technology Data Exchange (ETDEWEB)

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

Ma, D.C.; Gvildys, J.; Chang, Y.W.

1987-01-01

410

Solution structure of the kringle domain from urokinase-type plasminogen activator.  

UK PubMed Central (United Kingdom)

The solution structure of the kringle domain from urokinase-type plasminogen activator (u-PA) has been determined using 1H nuclear magnetic resonance spectroscopy and dynamical simulated annealing calculations. A total of 35 structures, 20 generated using a distance geometry method prior to simulated annealing and 15 generated using initial random phi, psi values, have been calculated based on 946 experimental nuclear Overhauser effect distance constraints and 48 dihedral angle constraints. Excluding the N- and C-terminal residues (-1 to 12, 77 to 82) and a number of surface residues (M18, G19, S42, D55 to R60, G67) that are disordered or flexible, the root mean square deviation values from the mean structure are 0.49(+/- 0.14) A and 0.65(+/- 0.16) A for the backbone atoms, and 1.03(+/- 0.21) A and 1.39(+/- 0.24) A for all heavy atoms, for the two sets of structures, respectively. An extended binding site for anionic polysaccharides such as heparin has been located on a relatively flat facet of the molecule, involving three consecutive arginines, R57, R58 and R60 (there is a deletion at site 59 of the consensus sequence), which form a cationic triad facing the solvent, and two histidines, H37 and H40, at the opposite end of the molecule. Comparison between the u-PA kringle structure and the crystal and NMR solution structures of tissue-type plasminogen activator kringle 2 has shown that the two proteins have similar global folds but demonstrate a number of local differences.

Li X; Bokman AM; Llinás M; Smith RA; Dobson CM

1994-02-01

411

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

Directory of Open Access Journals (Sweden)

Full Text Available Sandwich-type structures have proved to be alternatives of great success for several fields of application, and specially in the building sector. This is due to their outstanding properties of .specific rigidity and strength against bending loads and other range of advantages like fatigue and impact resistance, attainment of flat and smooth surfaces, high electric and thermal insulation, design versatility and some others. However, traditional sandwich structures present problems like their tendency towards delamination, stress concentrations in bores or screwed Joints, and pre resistance. These problems are alleviated thanks to the use of new sandwich structures built using three dimensional structures of advanced composite materials, maintaining the present advantages for more traditional sandwich structures. At this rate, these new structures can be applied in several areas where conventional sandwich structures used to be like walls, partitions, floor and ceiling structures, domes, vaults and dwellings, but with greater success.Las estructuras tipo sándwich han demostrado ser alternativas de gran éxito para diversos campos de aplicación y, en concreto, en el sector de la construcción, listo es gracias a sus excelentes propiedades de rigidez y resistencia específica frente a cargas de flexión y otra larga lista de ventajas, a la que pertenecen, por ejemplo, su buena resistencia a fatiga, resistencia al impacto, obtención de superficies lisas y suaves, elevado aislamiento térmico y eléctrico, versatilidad de diseño y otras. Sin embargo, las estructuras sándwich, tradicionales presentan una problemática consistente en su tendencia a la delaminación, concentraciones de tensiones ¿aparecidas ante la existencia de agujeros o uniones atornilladas y resistencia al fuego. Estos problemas son pifiados gracias a la aplicación de estructuras novedosas tipo sándwich, construidas a partir de tejidos tridimensionales de materiales compuestos avanzados, manteniéndose las ventajas existentes para las estructuras sándwich tradicionales. De este modo, estas nuevas estructuras pueden ser aplicadas en diversas áreas donde se venían aplicando las estructuras sándwich convencionales, pero con mayor éxito. Como son muros, tabiques, suelos, bóvedas, cúpulas, estructuras de suelo y techo y viviendas.

Castejón, L.; Jiménez, M. A.; Miravete, A.

1997-01-01

412

Oxide-ion conduction and dielectric relaxations for fluorite type structure  

International Nuclear Information System (INIS)

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

2011-01-01

413

The structure of human collagen type IX and its organization in fetal and infant cartilage fibrils.  

UK PubMed Central (United Kingdom)

Human collagen type IX was isolated from the media of organ cultures of fetal or infant hyaline cartilage. It consisted of three distinct, disulfide-bonded polypeptides of 115, 84, and 72 kDa, respectively. Digestion with chondroitinase ABC reduced the apparent molecular mass of the 115-kDa chain to about 65 kDa demonstrating that also human collagen type IX is a proteoglycan. In the electron microscope, the molecule had a rigid rod-like structure with characteristic kinks and with a globular domain at one end. Digestion of human collagen type IX with pepsin leads to somewhat heterogeneous fragments. Affinity-purified antibodies to the mixture of fragments specifically reacted with the fragment HMW without cross-reaction with chicken HMW. LMW of both species were recognized to the same low extent. Mechanically generated fibril fragments from human fetal cartilage were heterogeneous in diameter. Significantly, they could be immunostained for collagen type IX in a D-periodic pattern and regardless of the fibril diameter. Some fibrils were poorly labeled, again independently of the diameter. Therefore, the role of collagen type IX in cartilage probably is not to control directly the lateral growth during fibrillogenesis but rather to stabilize the fibril network.

Bruckner P; Mendler M; Steinmann B; Huber S; Winterhalter KH

1988-11-01

414

Pressure-induced phase transition of SmBi with a NaCl-type structure  

International Nuclear Information System (INIS)

By use of synchrotron radiation, powder x-ray diffraction of SmBi with a NaCl-type structure has been studied up to 30 GPa at room temperature. A first-order phase transition began to occur at around 16.2 GPa. SmBi transformed from the NaCl-type (B1) to the tetragonal (distorted CsCl-type) structure with the volume collapse of about 8.2 % at around 18.3 GPa. Crystal data of the single phase are a = 3.775(5) A, c = 3.25 (2) A, c/a = 0.86 and V = 46.4 (3) A3 at 20.3 GPa. The high-pressure form of SmBi is isostructural with that of SmAs. A bulk modulus of SmBi was estimated from the volume vs. pressure curve fitted by a Birch equation of state. The bulk modulus (B0) and its pressure derivative (B0') are 68 ± 3 GPa and 3.9 ± 0.3, respectively. The transition pressure and the bulk modulus of SmBi are larger than those of CeBi and PrBi. The structural high-pressure behaviour for SmX (X = P, As, Sb and Bi) is discussed. The structural phase transition of LaBi and NdBi occurred at around 11.5 GPa and 16.8 GPa, respectively. The transition pressures of LnBi (Ln = La, Ce, Pr, Nd and Sm) decreased with increasing lattice constant.

2010-03-01

415

Pressure-induced phase transition of SmBi with a NaCl-type structure  

Science.gov (United States)

By use of synchrotron radiation, powder x-ray diffraction of SmBi with a NaCl-type structure has been studied up to 30 GPa at room temperature. A first-order phase transition began to occur at around 16.2 GPa. SmBi transformed from the NaCl-type (B1) to the tetragonal (distorted CsCl-type) structure with the volume collapse of about 8.2 % at around 18.3 GPa. Crystal data of the single phase are a = 3.775(5) Å, c = 3.25 (2) Å, c/a = 0.86 and V = 46.4 (3) Å3 at 20.3 GPa. The high-pressure form of SmBi is isostructural with that of SmAs. A bulk modulus of SmBi was estimated from the volume vs. pressure curve fitted by a Birch equation of state. The bulk modulus (B0) and its pressure derivative (B0') are 68 ± 3 GPa and 3.9 ± 0.3, respectively. The transition pressure and the bulk modulus of SmBi are larger than those of CeBi and PrBi. The structural high-pressure behaviour for SmX (X = P, As, Sb and Bi) is discussed. The structural phase transition of LaBi and NdBi occurred at around 11.5 GPa and 16.8 GPa, respectively. The transition pressures of LnBi (Ln = La, Ce, Pr, Nd and Sm) decreased with increasing lattice constant.

Hayashi, J.; Toyama, T.; Takeda, K.; Shirotani, I.; Ohishi, Yasuo

2010-03-01

416

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

Science.gov (United States)

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

Jorge-Finnigan, Ana; Aguado, Cristina; Sanchez-Alcudia, Rocio; Abia, David; Richard, Eva; Merinero, Begona; Gamez, Alejandra; Banerjee, Ruma; Desviat, Lourdes R.; Ugarte, Magdalena; Perez, Belen

2010-01-01

417

A multilocus sequence typing scheme implies population structure and reveals several putative novel Achromobacter species.  

Science.gov (United States)

The genus Achromobacter currently is comprised of seven species, including Achromobacter xylosoxidans, an opportunistic and nosocomial pathogen that displays broad-spectrum antimicrobial resistance and is recognized as causing chronic respiratory tract infection in persons with cystic fibrosis (CF). To enable strain typing for global epidemiologic investigations, to clarify the taxonomy of "Achromobacter-like" strains, and to elucidate the population structure of this genus, we developed a genus-level multilocus sequence typing (MLST) scheme. We employed in silico analyses of whole-genome sequences of several phylogenetically related genera, including Bordetella, Burkholderia, Cupriavidus, Herminiimonas, Janthinobacterium, Methylibium, and Ralstonia, for selecting loci and designing PCR primers. Using this MLST scheme, we analyzed 107 genetically diverse Achromobacter isolates cultured from biologic specimens from CF and non-CF patients, 1 isolate recovered from sludge, and an additional 39 strains obtained from culture collections. Sequence data from these 147 strains, plus three recently genome-sequenced Achromobacter strains, were assigned to 129 sequence types based on seven loci. Calculation of the nucleotide divergence of concatenated locus sequences within and between MLST clusters confirmed the seven previously named Achromobacter species and revealed 14 additional genogroups. Indices of association showed significant linkage disequilibrium in all of the species/genogroups able to be tested, indicating that each group has a clonal population structure. No clear segregation of species/genogroups between CF and non-CF sources was found. PMID:22785192

Spilker, Theodore; Vandamme, Peter; Lipuma, John J

2012-07-11

418

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

International Nuclear Information System (INIS)

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

2008-10-03

419

A multilocus sequence typing scheme implies population structure and reveals several putative novel Achromobacter species.  

UK PubMed Central (United Kingdom)

The genus Achromobacter currently is comprised of seven species, including Achromobacter xylosoxidans, an opportunistic and nosocomial pathogen that displays broad-spectrum antimicrobial resistance and is recognized as causing chronic respiratory tract infection in persons with cystic fibrosis (CF). To enable strain typing for global epidemiologic investigations, to clarify the taxonomy of "Achromobacter-like" strains, and to elucidate the population structure of this genus, we developed a genus-level multilocus sequence typing (MLST) scheme. We employed in silico analyses of whole-genome sequences of several phylogenetically related genera, including Bordetella, Burkholderia, Cupriavidus, Herminiimonas, Janthinobacterium, Methylibium, and Ralstonia, for selecting loci and designing PCR primers. Using this MLST scheme, we analyzed 107 genetically diverse Achromobacter isolates cultured from biologic specimens from CF and non-CF patients, 1 isolate recovered from sludge, and an additional 39 strains obtained from culture collections. Sequence data from these 147 strains, plus three recently genome-sequenced Achromobacter strains, were assigned to 129 sequence types based on seven loci. Calculation of the nucleotide divergence of concatenated locus sequences within and between MLST clusters confirmed the seven previously named Achromobacter species and revealed 14 additional genogroups. Indices of association showed significant linkage disequilibrium in all of the species/genogroups able to be tested, indicating that each group has a clonal population structure. No clear segregation of species/genogroups between CF and non-CF sources was found.

Spilker T; Vandamme P; Lipuma JJ

2012-09-01

420

Experimental study on the local scour around a leg-type offshore structure  

Energy Technology Data Exchange (ETDEWEB)

When a jack-up rig or other leg-type platforms are settled on the sandy seabed, a local scour occurs around its legs depending upon the surrounding environmental conditions causing sinkage and inclination of the structure concerned. This paper explains the results of fixed-bed and movable-bed tests by using cylinders which were conducted to examine the local scouring characteristics of the leg type platforms and the water tank tests which were conducted in order to examine the footing configurations effective for reducing scour and sinkage of the jack-up rig. In other words, the development of a horse shoe vortex which is generated around the cylinder is elucidated and since its range of occurrence is within about 0.4D (diameter) from the side of the cylinder, it is expected that by covering the above range, scouring can be reduced. In addition, it is shown that the judgment on possibility of occurrence of local scouring in the operational water of leg type structures can almost be done by using the soil conditions and specific formulae. A study is also made on the prevention of scour and the countermeasures against the leg sinkage. 3 references, 10 figures, 6 tables.

Kubo, Keisaku

1988-09-01

 
 
 
 
421

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

Science.gov (United States)

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.

Cai, Zhao-kun; Fan, Ping; Zheng, Zhuang-hao; Liu, Peng-juan; Chen, Tian-bao; Cai, Xing-min; Luo, Jing-ting; Liang, Guang-xing; Zhang, Dong-ping

2013-09-01

422