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1

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

Science.gov (United States)

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

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

2014-05-01

2

Photocatalytic activity of glass ceramics containing Nasicon-type crystals  

International Nuclear Information System (INIS)

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

2013-01-01

3

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

4

RbSn2(PO43, a NASICON-type phosphate  

Directory of Open Access Journals (Sweden)

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

Dan Zhao

2011-05-01

5

Synthesis and electric conductivity of solid electrolyte of NASICON type  

International Nuclear Information System (INIS)

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

1988-01-01

6

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

7

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

8

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

International Nuclear Information System (INIS)

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

1982-05-14

9

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

International Nuclear Information System (INIS)

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

1988-01-01

10

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

11

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

International Nuclear Information System (INIS)

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

2013-05-01

12

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

International Nuclear Information System (INIS)

Compounds of formula Li1+xMIIIxTi2-x(PO4)3 with MIII = Cr, Fe and x = 0 and 0.05 have been prepared at soft temperatures using the Pechini synthesis method, based on sol-gel chemistry. The structural and microstructural characterization by X-ray diffraction and Scanning Electron Microscopy (SEM), shows that all of them crystallize in a NASICON-type structure with similar lattice parameters. Doping with Fe and Cr, causes an increase of the density of the samples after sinterization what clearly improves the ionic conductivity of the original material, LiTi2(PO4)3 until values of 9x10-4 S cm-1 at room temperature in the chromium-doped material. (Author)

2010-01-01

13

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

International Nuclear Information System (INIS)

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

1989-01-01

14

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-04-01

15

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

16

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

17

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

18

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

19

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

International Nuclear Information System (INIS)

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

2012-12-01

20

Synthesis and study of new compounds (M[sup I]) N[sup IV][sub 2](PO[sub 4])[sub 3] with Nasicon-like structure (M = Ag, Cu; N = Ge, Hf, Sn, Ti, Zr)  

Energy Technology Data Exchange (ETDEWEB)

Compounds (M[sup I])(N[sup IV])[sub 2](PO[sub 4])[sub 3] (M = Ag, Cu; N = Ge, Hf, Sn, Ti, Zr) have been synthesized using solid-state reactions. Attempts to synthesize CuGe[sub 2](PO[sub 4])[sub 3] did not succeed. All other compounds have Nasicon-like structure (space group R3c). AgGe[sub 2](PO[sub 4])[sub 3], AgHf[sub 2](PO[sub 4])[sub 3], CuSn[sub 2](PO[sub 4])[sub 3], and CuHf[sub 2](PO[sub 4])[sub 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. (Universite de Liege (Belgium))

1993-12-01

 
 
 
 
21

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

This work reports on the synthesis and characterization of NASICON prepared from SiO2, Na3PO4.12H2O and two types of zirconia: pure monoclinic ZrO2 and TZP (Tetragonal Polycrystalline Zirconia, with 3 mol% Y2O3) as raw materials. The classical ceramic method was used in all cases. SEM, XRD and DTA were used to follow the synthesis and sintering process, and impedance spectroscopy (IS) was used to study the electrical properties of sintered pellets. Results obtained with different NASICON samp...

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

1999-01-01

22

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-12-15

23

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

International Nuclear Information System (INIS)

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

2007-07-01

24

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

Energy Technology Data Exchange (ETDEWEB)

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

Catti, Michele

2001-02-01

25

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

International Nuclear Information System (INIS)

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

1986-01-01

26

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

27

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-09-01

28

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-12-06

29

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

Directory of Open Access Journals (Sweden)

Full Text Available Compounds of formula Li1+xMIIIxTi2-x(PO43 with MIII = Cr, Fe and x = 0 and 0.05 have been prepared at soft temperatures using the Pechini synthesis method, based on sol-gel chemistry. The structural and microstructural characterization by X-ray diffraction and Scanning Electron Microscopy (SEM, shows that all of them crystallize in a NASICON-type structure with similar lattice parameters. Doping with Fe and Cr, causes an increase of the density of the samples after sinterization what clearly improves the ionic conductivity of the original material, LiTi2(PO43 until values of 9x10-4 S cm-1 at room temperature in the chromium-doped material.Haciendo uso de la química sol-gel, se han preparado ortofosfatos de composición LiTi2(PO43 y Li1.05(Cr/Fe0.05Ti1.95(PO43 a temperaturas moderadas mediante el método Pechini. Estas fases han sido caracterizadas estructural y microestructuralmente por difracción de rayos X de polvo y microscopía electrónica de barrido (SEM, encontrándose que todas cristalizan en una estructura tipo NASICON, con parámetros de red muy similares. El dopaje con Fe y Cr permite aumentar la densidad de las muestras en la sinterización, mejorando de forma apreciable su conductividad iónica. Se ha observado un incremento de hasta cuatro órdenes de magnitud en la conductividad a temperatura ambiente obteniéndose una energía de activación de 0.29 eV para el material dopado con Cr.

Santamaría, J.

2010-02-01

30

Glass-ceramics based on phases with NZP-type structure  

Energy Technology Data Exchange (ETDEWEB)

Regions of glass formation are described that can be crystallized to glass-ceramics consisting of one or two phases with NaZr[sub 2]P[sub 3]O[sub 12]-type structure. One region is derived from NaGe[sub 2]P[sub 3]O[sub 12] through partial substitution of MgO for Na[sub 2]O; it yields glass-ceramics with high thermal expansion. By contrast, glass-ceramics with low or even negative thermal expansion are obtained from complex compositions of the type (Na, K)[sub 1-x](Mg, Ca, Sr)[sub x/2+y/2]Al[sub y]Ti[sub 2-y]P[sub 3]O[sub 12] with y[approx]1/2. With sodium contents above one mole per formula unit glass-ceramics can be obtained that show ionic conductivity. However, the large conductivities of sintered 'Nasicons' of analogous structure are not obtained, probably because of the structural complexity of the glass-ceramics. (orig.)

Mueller, G. (Fachbereich Materialwissenschaft, Fachgebiet Nichtmetallisch-Anorganische Werkstoffe, Technische Hochschule Darmstadt (Germany)); Schultz, S.G. (Fachbereich Materialwissenschaft, Fachgebiet Nichtmetallisch-Anorganische Werkstoffe, Technische Hochschule Darmstadt (Germany)); Mildner, M. (Fachbereich Materialwissenschaft, Fachgebiet Nichtmetallisch-Anorganische Werkstoffe, Technische Hochschule Darmstadt (Germany))

1994-09-01

31

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1979-01-01

32

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

Science.gov (United States)

The lithium conductors Li 2FeTi(PO 4) 3 and Li 2FeZr(PO 4) 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 LiZr 2(PO 4) 3. Four (001) layers of PO 4 and (Fe, Ti)O 6 polyhedra are present per unit-cell, and they are related both by overline1 inversion centers ( ? structure) and by a glide planes ( ? structure). Ti 4+ and Fe 3+ order in the two interlayer regions, respectively. Owing to the structure complexity, only half of the lithium atoms could be refined in tetrahedral coordination with =1.99 Å. Li 2FeZr(PO 4) 3 (orthorhombic Pbna, Z=4; a=8.70559(8), b=8.78572(9), c=12.2202(1) Å) proved to be similar to ?-LiZr 2(PO 4) 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 LiZr 2(PO 4) 3.

Catti, Michele

2001-02-01

33

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

34

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

International Nuclear Information System (INIS)

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

2004-07-15

35

Recycling Caustic from LAW Stream using NaSICON Membrane based Electrochemical Technology  

International Nuclear Information System (INIS)

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

2009-03-01

36

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

International Nuclear Information System (INIS)

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

2013-02-25

37

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

38

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

39

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

International Nuclear Information System (INIS)

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

2009-01-01

40

Na/sub 4/Nb(PO/sub 4/)/sub 3/, a material with a reversible crystal-glass transformation: structural and optical comparison  

Energy Technology Data Exchange (ETDEWEB)

The phosphate Na/sub 4/Nb(PO/sub 4/)/sub 3/ exhibits a reversible crystal-phase change. Raman and optical investigations give evidence of the similarity between the covalent skeleton of the Nasicon-like crystalline phosphate and the network of the glass. Both types of materials contain octahedral NbO/sub 6/ groups with various Nb-O lengths. It is shown for the neodymium-doped glasses that these structural features induce a strong self concentration quenching of the Nd/sup 3 +/ emission.

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

1988-06-01

 
 
 
 
41

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

42

Caustic Recycle from Hanford Tank Waste Using NaSICON Ceramic Membranes  

International Nuclear Information System (INIS)

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

2008-07-15

43

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

DEFF Research Database (Denmark)

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

Bentzen, Janet Jonna; Nicholson, Patrick S.

1980-01-01

44

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-02-25

45

Polar structures in late-type galaxies  

Digital Repository Infrastructure Vision for European Research (DRIVER)

A common point of view is that stable polar structures are mainly present in the E/S0 early-type galaxies lacking dense gas in their host disks. However, nuclear, as well as external polar rings and disks also exist in the late-type hosts, including gas-rich dwarf galaxies. Using the 3D spectroscopic observations of these objects we can derive the rotation properties of the gas components separately in the main and polar planes. The most detailed picture of the gas kinematic...

Moiseev, Alexei

2014-01-01

46

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

47

Structure of a type IV secretion system.  

Science.gov (United States)

Bacterial type IV secretion systems translocate virulence factors into eukaryotic cells, distribute genetic material between bacteria and have shown potential as a tool for the genetic modification of human cells. Given the complex choreography of the substrate through the secretion apparatus, the molecular mechanism of the type IV secretion system has proved difficult to dissect in the absence of structural data for the entire machinery. Here we use electron microscopy to reconstruct the type IV secretion system encoded by the Escherichia coli R388 conjugative plasmid. We show that eight proteins assemble in an intricate stoichiometric relationship to form an approximately 3?megadalton nanomachine that spans the entire cell envelope. The structure comprises an outer membrane-associated core complex connected by a central stalk to a substantial inner membrane complex that is dominated by a battery of 12 VirB4 ATPase subunits organized as side-by-side hexameric barrels. Our results show a secretion system with markedly different architecture, and consequently mechanism, to other known bacterial secretion systems. PMID:24670658

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

2014-04-24

48

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

49

Liquid-filled type vibration damping structure  

Energy Technology Data Exchange (ETDEWEB)

A liquid-filled type vibration damping structure is described comprising: a liquid-filled vibration isolator having (a) first and second frames respectively mounted on a vibration source and on the side of a vehicle body; (b) resilient member connected between the first and second frames; (c) a diaphragm secured to the first frame; (d) a baffle member secured onto the first frame and dividing an internal space surrounded by the resilient member, the diaphragm, and the second frame into first and second liquid chambers, the baffle member further having a hole and a first aperture for communicating the first and second liquid chambers with each other; (e) a holder cooperating with the baffle member to form therebetween an orifice portion communicated with the hole of the baffle member and having at least one aperture aligned with the first aperture of the baffle member; (f) a movable plate held by at least the holder between the apertures of the holder and the baffle member and moved with respect to the baffle member by the liquid flow through the apertures of the holder and the baffle member; and (g) at least one mass body attached into the resilient member to reduce the resilient coefficient. The structure further comprising: a bracket member for mounting the vibration isolator onto the vibration source at a predetermined angle of inclination with respect to the direction of vibration from the source; and the angle is sufficient to suppress the generation of a liquid column resonance peak.

Tabata, T.

1987-06-16

50

Structural stability of fluorite-type structure oxides under irradiation  

International Nuclear Information System (INIS)

Oxides with the fluorite-type structure are radiation tolerant materials. They are widely used or envisaged in hostile nuclear environments, such as nuclear fuels or inert transmutation matrices for actinide burning. Study of the radiation crystal stability of this class of solids in various radiative fields is of major importance. The actinide fission leads to the formation of two fission fragments of great kinetic energy, which slow down and in fine stop in the material. These processes define the two main contributions of fission: 1)the ballistic contribution (creation of irradiation defects) 2)the chemical contribution (modification of the material composition by doping). These two contributions affect the structural stability of the material: structural modifications due to the accumulation of irradiation defects (crystalline-amorphous transition), fragmentation of the material due to the presence of high concentration heteroatoms responsible of bubbles formation. These two parameters are the most important for the radiation structural stability of materials. The studies led on materials irradiated in reactor are difficult because the environment is very radiative and limits considerably the possible studies. On the other hand, the use of middle energy small accelerators, such as those available on the JANNUS irradiation platform (CEA-CNRS), allow to experimentally simulate the irradiation effects while being free of all the effective radioactivity. The external ionic bombardment of charged mono kinetic particles offers the opportunity to simulate experimentally the damage resulting of fission in a large range of energy and projectiles (the ratio of the electronic and nuclear contributions of the energy deposition being controlled), and leads thus to the separation of the ballistic and chemical contributions. Moreover, the ion beams characterization techniques (RBS..) allows the fine characterization of the structural and chemical transformations of the surface of the materials submitted to different treatments. The paper will illustrate the potentialities offered by the use of the ion beam techniques as simulation and characterization tool of the irradiation effects, in beginning by the case of binary fluorite-type structure oxides. (O.M.)

2008-06-02

51

Homotopy type and A?-group structure  

International Nuclear Information System (INIS)

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

1998-10-31

52

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

Science.gov (United States)

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

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

2006-06-01

53

Induced Dirac structure on isotropy type manifolds  

CERN Document Server

A new method of singular reduction is extended from Poisson to Dirac manifolds. Then it is shown that the Dirac structures on the strata of the quotient coincide with those of the only other known singular Dirac reduction method.

Ratiu, Tudor S

2010-01-01

54

New structure type of Lu5Ni19B6  

International Nuclear Information System (INIS)

The powder method was used to investigate Lu5-Ni19B6 structure belonging to a new type: sp. g. P6/mmm, a=0.4943(1), c=1.7161(9) nm, N=30 (R=0.120). The L45Ni19B6 structure is a new representative of the homologous series based on CaCu5 and CeCo3B2 types; its elementary cell contains two layers of CaCu5 type structure and three layers of CeCo3B2 type structure. Structure of the new L45Ni19B6 type belongs to the class of structures with trigonal-prismatic coordination of smallest atoms

1985-01-01

55

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-07-15

56

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

57

Dusty Structure Around Type 1 AGNs  

Science.gov (United States)

We present a detailed investigation of the MIR continuum emission of type 1 QSOs and define the main emission components. Our model requires three components: a clumpy torus, dusty narrow-line region (NLR) clouds and a blackbody-like hot dust.

Mor, Rivay; Netzer, Hagai; Elitzur, Moshe

2010-05-01

58

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

59

Structural biology of type VI secretion systems  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type VI secretion systems (T6SSs) are transenvelope complexes specialized in the transport of proteins or domains directly into target cells. These systems are versatile as they can target either eukaryotic host cells and therefore modulate the bacteria–host interaction and pathogenesis or bacterial cells and therefore facilitate access to a specific niche. These molecular machines comprise at least 13 proteins. Although recent years have witnessed advances in the role and function of these...

Cascales, Eric; Cambillau, Christian

2012-01-01

60

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1992-03-30

 
 
 
 
61

Comments on structural types of toroidal carbon nanotubes  

CERN Multimedia

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

Chuang, Chern; Jin, Bih-Yaw

2012-01-01

62

Reactor core structure in FBR type reactors  

International Nuclear Information System (INIS)

Purpose: To improve the seismic-proofness of a reactor core without increasing the pitch and the bending load of reactor components. Constitution: In the reactor core of FBR type reactors, reactor components of fuel assemblies exhibit group vibration behaviors and upper and intermediate pat portions are destructed due to the colliding force in the vibrations to possibly reduce the integrity of the reactor components. In view of the above, a wrapper tube as the reactor components disposed to the outside of the reactor core are made so as to have substantially identical outer diameter with the wrapper tubes for other reactor components and made thicker than the wrapper tubes for other reactor components. In this way, the strength of the wrapper tubes for the reactor components disposed to the outside of the reactor core is increased and the earthquake proofness of the reactor core can be improve without increasing the pitch and the bending load thereof. (Takahashi, M.)

1985-04-02

63

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 statistical measures of structural stress variations the modal spectral analysis method is applied.

2010-01-01

64

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 statistical measures of structural stress variations the modal spectral analysis method is applied.

1988-01-01

65

Prediction of Type A behaviour : a structural equation model  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2009-01-01

66

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

1991-10-01

67

Structure and Regulation of the Type VI Secretion System  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The type VI secretion system (T6SS) is a complex and widespread gram-negative export pathway with the capacity to translocate protein effectors into a diversity of target cell types. Current structural models of the T6SS indicate that the apparatus is composed of at least two complexes, a dynamic bacteriophage-like structure and a cell envelope-spanning membrane-associated assembly. How these complexes interact to promote effector secretion and cell targeting remains a major question in the f...

Silverman, Julie M.; Brunet, Yannick R.; Cascales, Eric; Mougous, Joseph D.

2012-01-01

68

Transient electromagnetic and structure analysis of BELlows type vacuum vessels  

International Nuclear Information System (INIS)

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

1986-01-01

69

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

70

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

71

Prediction of Type A behaviour: a structural equation model  

Scientific Electronic Library Online (English)

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

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

72

The Three-Dimensional Structural Basis of Type II Hyperprolinemia  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type II hyperprolinemia is an autosomal recessive disorder caused by a deficiency in ?1-pyrroline-5-carboxylate dehydrogenase (P5CDH, aka ALDH4A1), the aldehyde dehydrogenase that catalyzes the oxidation of glutamate semialdehyde to glutamate. Here we report the first structure of human P5CDH 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 human P5CDH was...

2012-01-01

73

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

74

Optimization of structure of multicell-type transistor converter  

Directory of Open Access Journals (Sweden)

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

Bondarenko Yu. V.

2012-02-01

75

A Quasi-Type-1 Phase-Locked Loop Structure  

DEFF Research Database (Denmark)

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

Golestan, Saeed; Freijedo, Francisco

2014-01-01

76

Prediction of type A behaviour: A structural equation model  

Directory of Open Access Journals (Sweden)

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

How to cite this article:

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

Marius Pretorius

2009-04-01

77

Structural Insights into Fibronectin Type III Domain Mediated Signaling  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The alternatively spliced type-III extradomain B (EIIIB) of Fibronectin (FN) is only expressed during embryogenesis, wound healing and tumorigenesis. The biological function of this domain remains unclear. We describe here the first crystal structure of the interface between alternatively-spliced domain EIIIB and its adjacent FN type-III domain 8 (FN B-8). The opened CC? loop of EIIIB and the rotation and tilt of EIIIB domain allows good access to the FG loop of FN-8 which is normally hinde...

Bencharit, Sompop; Cui, Cai Bin; Siddiqui, Adnan; Howard-williams, Escher L.; Sondek, John; Zuobi-hasona, Kheir; Aukhil, Ikramuddin

2007-01-01

78

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

2001-07-11

79

Notes on SU(3) Structures in Type IIB Supergravity  

CERN Document Server

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.

Frey, A R

2004-01-01

80

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)

2004-06-01

 
 
 
 
81

Structural Characterization of Nanosheet-type MFI Zeolite  

Science.gov (United States)

Zeolites are microporous crystalline aluminosilicates and have ordered micropores of a few Å in the structure. Zeolites are widely used in petrochemistry and fine-chemical synthesis because strong acid sites within their uniform micropores enable size- and shape-selective catalysis. Here we show that appropriately designed bifunctional surfactants can direct the formation of zeolite structures on the mesoporous and microporous length scales simultaneously, and thus produce nanosheet-type MFI zeolite that are only 2 nm thick, which corresponds to the b-axis dimension of a single MFI unit cell. The nanosheet-type MFI zeolite showd a significantly increased surface area, high catalytic activities, and excellent thermal and hydrothermal stability.

Sakamoto, Yasuhiro; Choi, Minkee; Na, Kyungsu; Kim, Jeongnam; Park, Woojin; Ryoo, Ryong; Terasaki, Osamu

82

Structural and serological relatedness of Haemophilus influenzae type b pili.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The structural and serological relatedness of the pilus proteins of several isolates of Haemophilus influenzae type b cultured from patients with invasive disease and from different anatomic sites within the same patient was examined. Epithelial cell-adherent variants of 25 nonadherent parent isolates were obtained by selection for organisms that adhered to human erythrocytes. Outer membrane protein analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed the presence of...

Lipuma, J. J.; Gilsdorf, J. R.

1988-01-01

83

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

84

The Three-Dimensional Structural Basis of Type II Hyperprolinemia  

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-08-31

85

Electronic structure and magnetism of CrTe with NiAs-type structure  

Energy Technology Data Exchange (ETDEWEB)

Electronic structures of CrTe with the hexagonal NiAs-type structure are calculated at the lattice parameters observed recently under the pressures, by the self-consistent full potential linearized augmented plane wave (FLAPW) method. A contour map of the valence electron density is calculated. A strong mixing bond between the nearest neighbor Cr and Te is obtained.

Nakada, K. E-mail: nakada@landau.shinshu-u.ac.jp; Shimizu, H.; Yamada, H

2004-05-01

86

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 hav...

2010-01-01

87

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

Science.gov (United States)

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

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

2009-12-01

88

Structure and evolution of low mass W UMa type systems  

CERN Document Server

The structure and evolution of low mass W UMa type contact binaries are discussed by employing Eggleton's stellar evolution code. Assuming that these systems completely satisfy Roche geometry, we calculate the relative radii of both components of contact binaries in different contact depth between inner and outer Roche lobes. We obtain a radius grid of contact binaries, and can ensure the surfaces of two components lying on an equipotential surface by interpolation using this radius grid when we follow the evolution of the contact binaries. We assume that the energy transfer takes place in the different regions of the common envelope to investigate the effects of the region of energy transfer on the structure and evolution of contact binaries. We find that the region of energy transfer has significant influence on the structure and evolution of contact binaries, and conclude that the energy transfer may occur in the outermost layers of the common convective envelope for W-type systems, and this transfer takes...

Li, L; Zhang, F; Li, Lifang; Han, Zhanwen; Zhang, Fenghui

2004-01-01

89

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)

2007-03-01

90

Doping and Defect Structure of Tetradymite-Type Crystals  

Science.gov (United States)

Nonstoichiometry of tetradymite-type crystals A{2/V}B{3/VI} that are grown from stoichiometric melts leads to the formation of native defects in the crystal lattice (predominantly antisite defects, A{B/-1} and vacancies V{B/+2} in the anion sublattice). This paper summarizes the basic ideas concerning a point defect model in A{2/V}B{3/VI} crystals. It turns out that a variety of doping elements interact with the native defects. Such interactions alter the concentration of free charge carriers, affect the doping efficiency, and modify the transport properties. Detailed understanding of the defect structure in tetradymite-type crystals is very important as it impacts on the efficiency of these materials when used as active elements in thermoelectric coolers.

Drasar, C.; Lostak, P.; Uher, C.

2010-09-01

91

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

2006-06-29

92

The Importance of Disk Structure in Stalling Type I Migration  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 orb...

Kretke, Katherine A.; Lin, D. N. C.

2012-01-01

93

Narrowband frequency-drift structures in solar type IV bursts  

Science.gov (United States)

We have established the Zao Solar Radiospectrograph (ZSR), a new solar radio observation system, at the Zao observatory of Tohoku University, Japan. We observed narrowband fine structures with type IV bursts with ZSR on 2 and 3 November 2008. The observed fine structures are similar to fiber bursts in terms of the drift rates and the existence of emission and absorption stripes. Statistical analysis of the drift rates, however, shows that the observed fine structures are different from the ordinary fiber bursts as regards the sense and the magnitude of their drift rates. First, the observed drift rates include both positive and negative rates, whereas ordinary fiber bursts are usually characterized by negative drift rates. Second, the absolute values of the observed drift rates are tens of MHz s-1, whereas the typical drift rate of fiber bursts at 325 MHz is approximately -9 MHz s-1. In addition, all fine structures analyzed have narrow emission bands of less than 17 MHz. We also show that the observed narrowband emission features with drift rates of approximately 40 MHz s-1 can be interpreted as the propagation of whistler-mode waves, which is the same process as that underlying fiber bursts.

Nishimura, Y.; Ono, T.; Tsuchiya, F.; Misawa, H.; Kumamoto, A.; Katoh, Y.; Masuda, S.; Miyoshi, Y.

2013-12-01

94

The Importance of Disk Structure in Stalling Type I Migration  

CERN Document Server

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

Kretke, Katherine A

2012-01-01

95

THE IMPORTANCE OF DISK STRUCTURE IN STALLING TYPE I MIGRATION  

International Nuclear Information System (INIS)

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 ? 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 ? 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.

2012-08-10

96

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

97

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.

98

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.

2011-03-01

99

Anomalous electronic structures of transition-metal oxides with hollandite-type crystal structure  

Science.gov (United States)

We make the electronic structure calculations of transition-metal oxides with a hollandite-type crystal structure A2M8O16 using the generalized gradient approximation (GGA) in the density functional theory, where the Hubbard-type repulsive interaction is taken into account (GGA+U). We first examine the electronic structure of the 3d series (M=Ti, V, Cr, Mn) as well as the 4d series (M=Mo, Ru, Rh) to discuss their generic features. We then discuss in particular the origins of the metal-insulator transition observed in K2Cr8O16 and quasi-one-dimensional electron conduction observed in K2Ru8O16. We also consider the observed metal-insulator transition in K2V8O16 where the effect of electron correlations may play an essential role.

Toriyama, T.; Konishi, T.; Ohta, Y.

2012-12-01

100

Anomalous electronic structures of transition-metal oxides with hollandite-type crystal structure  

International Nuclear Information System (INIS)

We make the electronic structure calculations of transition-metal oxides with a hollandite-type crystal structure A2M8O16 using the generalized gradient approximation (GGA) in the density functional theory, where the Hubbard-type repulsive interaction is taken into account (GGA+U). We first examine the electronic structure of the 3d series (M=Ti, V, Cr, Mn) as well as the 4d series (M=Mo, Ru, Rh) to discuss their generic features. We then discuss in particular the origins of the metal-insulator transition observed in K2Cr8O16 and quasi-one-dimensional electron conduction observed in K2Ru8O16. We also consider the observed metal-insulator transition in K2V8O16 where the effect of electron correlations may play an essential role.

2012-12-14

 
 
 
 
101

Gradient type optimization methods for electronic structure calculations  

CERN Document Server

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

Zhang, Xin; Wen, Zaiwen; Zhou, Aihui

2013-01-01

102

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

103

Structure of the atmosphere of late-type stars  

International Nuclear Information System (INIS)

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

1976-01-01

104

Mechanism and structure of the bacterial type IV secretion systems.  

Science.gov (United States)

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

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

2014-08-01

105

Perovskite-type oxides - Oxygen electrocatalysis and bulk structure  

Science.gov (United States)

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

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

1988-01-01

106

New germanide superconductors with the type-I clathrate type structure  

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-11-15

107

Structural controls of shihongtan sandstone-type uranium deposit in the southwestern turpan-hami basin  

International Nuclear Information System (INIS)

Through studying the structural evolution, structural characteristics of Shihongtan sandstone-type uranium deposit, it is found that there are three types of structural controls on Shihongtan sandstone-type uranium deposit on the Aiding structural slope, namely, the uranium sources, types of the sedimentary formation of target horizons and the mineralization epochs are controlled by the structural evolution of the basin; the mineralization area are controlled by the structural slope units; the distribution of uranium ore bodies is controlled by the second order structures on the structural slope. (authors)

2006-03-01

108

Type IIA orientifolds on SU(2)-structure manifolds  

International Nuclear Information System (INIS)

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

2010-01-01

109

``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

110

Structure of lower portion of PWR type reactor  

Energy Technology Data Exchange (ETDEWEB)

The present invention provide a structure of a lower portion of a PWR type reactor, which can keep molten materials of a reactor container before a reactor core molten accident reaches a large scale. Namely, the structure of the lower portion of the reactor has a large number of ceramic members disposed on the upper portion of a lower end plate in a state where they do not undergo undesired effects by the flow of coolants. Preferably, a disk covering the upper surface of the ceramic member for isolating it from coolant flows in a lower plenum is suspended and held from a lower reactor core support plate. With such a constitution, when a meltdown accident should occur, the ceramic molded products laid over the upper surface of the lower end plate of the reactor container receive the molten reactor core. Accordingly, the end plate disposed therebelow can be protected and can be prevented from melt-perforation. In addition, since the ceramic molded products are isolated from streams of coolants by the disk in communication with the lower portion of the reactor core, their performance can be kept for a long period of time. (I.S.)

Matsuoka, Tsuyoshi

1998-10-09

111

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

112

Multivalent ion conducting solids  

Energy Technology Data Exchange (ETDEWEB)

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

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

2008-07-01

113

Kerogen: from types to models of chemical structure; Les kerogenes: de la notion de types aux modeles de structure chimique  

Energy Technology Data Exchange (ETDEWEB)

The aim of the present paper is to review the conceptual and analytical developments in the period 1970-1990 which have led, through kerogen isolation and analysis on the one hand, and case studies of petroleum systems on the other hand, to the concept of kerogen types, evolution paths, and statistical chemical models. Kerogen is defined as the sedimentary organic matter generating petroleum, an insoluble product as opposed to its counterpart soluble in usual organic solvents, such as petroleum. As kerogen is a complex organic material intimately mixed with minerals in sediments, the first task was to set up a robust procedure for its isolation, enabling then its study by various physicochemical analyses. The parallel development of oil exploration, resulting in geological sample availability, made the geochemical comparison of various petroleum systems possible. Comparisons concerned not only oils, source rock extracts and kerogen compositions, but also the timing of petroleum generation. The notion of kinetic cracking of kerogen into petroleum stemming from these case studies, associated with the observation of time and temperature compensation, resulted in the use of pyrolysis to evaluate the oil potential still to be generated by the kerogen, and in the construction of the Rock-Eval. In the mid-70's, all main parameters on kerogens from reference series of source rocks were available to define the notions of types and evolution paths of kerogens upon geological maturation. A further important step for improving the knowledge of kerogen composition was achieved in the 80's using new techniques of analytical and preparative pyrolysis and their coupling with different detectors. The pyrolysis products, small building blocks issued from the kerogen thermal cracking, could thus be analyzed and quantified at the molecular level, without the problems of representativeness associated with natural extract analyses, such as loss of volatile fractions or product migration out of source rocks. Contemporaneous developments in solid state {sup 13}C NMR allowed quantification of the various forms of carbon and their molecular environment in the kerogen, whereas quantification was not possible with IR or UV spectroscopy. The quantification of molecular building blocks and their bonding functional groups in kerogens allowed conceptual averaged molecular models of kerogens to be proposed in order to visualize their atomic and molecular composition, and the changes occurring in this composition according to types and maturity. Although it will never be possible to represent a true kerogen structure, simply because it is a mixture of various non-polymeric macromolecules, an hypothetical average structure of kerogen, representing a large amount of information from various analyses, can provide a synthetic view of the main resemblances and differences among sedimentary organic matters. (author)

Vandenbroucke, M. [Institut Francais du Petrole (IFP), Div. Geologie-Geochimie, 92 - Rueil-Malmaison (France)

2003-07-01

114

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

Science.gov (United States)

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

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

2009-03-01

115

Continuity chords of bands and band structure of semiconducting compounds with TlSe-type structure  

International Nuclear Information System (INIS)

All the simple band representations of the space group D/sub 4h//sup 18/ are constructed. Using the concept of band representation and continuity chord, developed by Zak, it is shown that for semiconducting compounds with TlSe-type structure it is possible to extract some useful information about the character of localization of basic functions, belonging to the same band, i.e. in fact about the nature of the chemical bond responsible for the observed band structure. In particular, from the comparison with a calculated band structure of the ternary semiconducting compounds with TlSe-type structure, it is shown that the lower four valence bands correspond to s-states of chalcogen atoms. Two following valence bands correspond to s-states of three-valent cations. Then, a large group of ten valence bands is produced by p/sub z/-states of chalcogen atoms and p/sub x/-, p/sub y/-, p/sub z/-states of three-valent cations. (author)

1985-09-01

116

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

International Nuclear Information System (INIS)

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

2003-08-17

117

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2009-07-15

118

Muscle fibre types of fishes; structural and functional specialization  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Akster, H. A.

1984-01-01

119

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

International Nuclear Information System (INIS)

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

1995-05-01

120

A New Type of Center Data Structure in Cloud Computing  

Directory of Open Access Journals (Sweden)

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

Guo Xiaohui

2014-01-01

 
 
 
 
121

Nanoporous titanium borophosphates with rigid gainesite-type framework structure.  

Science.gov (United States)

Nanoporous titanium borophosphates have been synthesized which exhibit a rigid gainesite-type framework of polyhedra. The open-framework character is supported by the reversibility of de- and rehydration processes. PMID:21952640

Zhou, Yan; Hoffmann, Stefan; Menezes, Prashanth W; Carrillo-Cabrera, Wilder; Huang, Ya-Xi; Vasylechko, Leonid; Schmidt, Marcus; Prots, Yurii; Deng, Jin-Feng; Mi, Jin-Xiao; Kniep, Rüdiger

2011-11-14

122

Type III secretion systems and bacterial flagella: Insights into their function from structural similarities  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type III secretion systems and bacterial flagella are broadly compared at the level of their genetic structure, morphology, regulation, and function, integrating structural information, to provide an overview of how they might function at a molecular level.

Blocker, Ariel; Komoriya, Kaoru; Aizawa, Shin-ichi

2003-01-01

123

New insights into structure and function of type I collagen  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Collagen is one of the most abundant proteins in mammalians and strongly conserved throughout evolution. It constitutes one third of the human proteome and comprises three-quarters of the dry weight of human skin. It is widely accepted as a major structural component in animal body such as in bones, cartilage and skins. More and more studies have shown that, in addition to the structural function, collagens can induce or regulate many cellular functions and processes such as cell differentiat...

Xiong, Xin

2008-01-01

124

Structure of human type II 5 alpha-reductase gene.  

Science.gov (United States)

The best known activity of steroid 5 alpha-reductase is the transformation of testosterone into dihydrotestosterone, the most potent androgen. Two types of human steroid 5 alpha-reductase cDNAs and the type I gene have previously been isolated and characterized. This report describes the isolation and characterization of the human type II 5 alpha-reductase gene, the gene most likely responsible for male pseudohermaphroditism due to 5 alpha-reductase deficiency as well as the one presumed to be involved in a major androgen-related diseases such as prostate cancer and benign prostatic hyperplasia. The type II 5 alpha-reductase gene contains five exons of 352, 164, 102, 151 and 1695 bp, respectively, which share 43.8% to 64.1% homology with exons of the corresponding type I gene. These exons are separated by four introns of greater than 29, and approximately 2.3, 2.0 and 3.0 kb. Analysis of primer extension products by polyacrylamide gel electrophoresis as well as by subcloning and sequencing reveals a start site located 71 nucleotides upstream the ATG initiating codon. PMID:1505484

Labrie, F; Sugimoto, Y; Luu-The, V; Simard, J; Lachance, Y; Bachvarov, D; Leblanc, G; Durocher, F; Paquet, N

1992-09-01

125

Structures of the Mating-Type Loci of Cordyceps takaomontana  

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Yokoyama, Eiji; Yamagishi, Kenzo; Hara, Akira

2003-01-01

126

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

127

Well-formedness and typing rules for UML Composite Structures  

CERN Document Server

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

Dragomir, Iulia

2010-01-01

128

Tb2Ni2Mg3: a new structure type derived from the Ru3Al2B2 type  

International Nuclear Information System (INIS)

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

2007-02-01

129

Perovskite-type oxides: Oxygen electrocatalysis and bulk structure  

Science.gov (United States)

Perovskite-type oxides have been considered for use as oxygen reduction and generation electrocatalysts in alkaline electrolytes. This paper is concern Perovskite oxides have not been found, in general, to be very active for oxygen reduction, although substantial catalytic activity for hydrogen peroxid A series of compounds of the type LaFe xNi 1- xO 3 has been used as a model system to gain information on the possible relationships be MES also shows that the introduction of Ni into the FE(III) matrix of LaFeO 3 forces some of the FE(III) into the unusual FE(IV) state, while part o The hydrogen peroxide decomposition rates have been found to undergo a substantial change in the range 0.25 < x < 0.5. A correlation has been f

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

130

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

131

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

DEFF Research Database (Denmark)

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

Hamming, Ole Jensen; Lutfalla, Georges

2011-01-01

132

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

133

Subband structure comparison between n- and p- type double delta-doped Ga As quantum wells  

Energy Technology Data Exchange (ETDEWEB)

We compute the electron level structure (n-type) and the hole subband structure (p-type) of double -doped GaAs (DDD) quantum wells, considering exchange effects. The Thomas-Fermi (TF), and Thomas-Fermi-Dirac (TFD) approximations have been applied in order to describe the bending of the conduction and valence band, respectively. The electron and the hole subband structure study indicates that exchange effects are more important in p-type DDD quantum wells than in n-type DDD Also our results agree with the experimental data available. (Author) 33 refs., 2 tabs., 5 figs.

Rodriguez V, I.; Gaggero S, L.M. [Facultad de Ciencias, Universidad Autonoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, 62210 Cuernavaca, Morelos (Mexico)

2004-07-01

134

Subband structure comparison between n- and p- type double delta-doped Ga As quantum wells  

International Nuclear Information System (INIS)

We compute the electron level structure (n-type) and the hole subband structure (p-type) of double -doped GaAs (DDD) quantum wells, considering exchange effects. The Thomas-Fermi (TF), and Thomas-Fermi-Dirac (TFD) approximations have been applied in order to describe the bending of the conduction and valence band, respectively. The electron and the hole subband structure study indicates that exchange effects are more important in p-type DDD quantum wells than in n-type DDD Also our results agree with the experimental data available. (Author) 33 refs., 2 tabs., 5 figs

2004-01-01

135

Ferroelectric properties of compounds with magnesium ortho - tellurate structural type  

International Nuclear Information System (INIS)

Complex study was made on structure, phase transformations and electrophysical properties of ceramic samples of Mg3TeO6, Mn3TeO6, CdMn2TeO6 and CdMnTeO6 compounds. The conclusion was drawn that the last three compounds are ferroelectrics with 510, 570 and 480 K Curie points and in the first one the transformation into spontaneous-polarized state at 520 K takes place

1982-11-01

136

The structural stability of wild-type horse prion protein.  

Science.gov (United States)

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

Zhang, Jiapu

2011-10-01

137

Electron density - structure relationships in some perovskite-type compounds  

International Nuclear Information System (INIS)

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

1995-12-01

138

Few non-minimal types and non-structure  

CERN Multimedia

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

Shelah, S

1999-01-01

139

Coronal structure and rotation in late-type stars  

International Nuclear Information System (INIS)

Soft X-ray spectra, obtained with the HEAD-2 IPC, are analysed for 34 late-type stars. The sample includes single stars, binaries (many of which are named RS CVn systems), two FK Com stars, and a BY Ora star. The authors fitted observed spectra (0.15-4. keV) to single-temperature model spectra to obtain the effective coronal X-ray temperature T and the specific emission measure. The fits appear to be adequate approximations for most of the observed spectra

1983-10-01

140

Realization of body centered tetragonal, ?-tin and diamond type structures using five beam interference  

Science.gov (United States)

A five beam interference configuration, with one central circularly polarized beam and four linearly polarized side beams incident at equal tilt angles in two orthogonal planes, is investigated for realization of three dimensional periodic structures. It was observed that when the two pairs of linearly polarized waves are TE-TM polarized, dumb-bell shaped pattern and body centered tetragonal lattice structures could be realized. And when all the four linearly polarized waves are TE polarized, with circularly polarized central beam, woodpile type structures and ?-tin type structure could be formed. The obtained ?-tin type structure was found to get transformed into diamond cubic type structure when the angle of incidence was increased to an optimum value.

Sidharthan, Raghuraman; Kumar, Manish; Joseph, Joby; Murukeshan, Vadakke Matham

2014-07-01

 
 
 
 
141

Relationship Structures and Semantic Type Assignments of the UMLS Enriched Semantic Network  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Objective: The Enriched Semantic Network (ESN) was introduced as an extension of the Unified Medical Language System (UMLS) Semantic Network (SN). Its multiple subsumption configuration and concomitant multiple inheritance make the ESN's relationship structures and semantic type assignments different from those of the SN. A technique for deriving the relationship structures of the ESN's semantic types and an automated technique for deriving the ESN's semantic type assignments from those of th...

2005-01-01

142

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

Motizuki, K.; Morifuji, M.

1988-01-01

143

Understanding the Structural Scaling Relations of Early-Type Galaxies  

CERN Document Server

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

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

2014-01-01

144

Ferroelectric properties of compounds with magnesium ortho - tellurate structural type  

Energy Technology Data Exchange (ETDEWEB)

Complex study was made on structure, phase transformations and electrophysical properties of ceramic samples of Mg/sub 3/TeO/sub 6/, Mn/sub 3/TeO/sub 6/, CdMn/sub 2/TeO/sub 6/ and CdMnTeO/sub 6/ compounds. The conclusion was drawn that the last three compounds are ferroelectrics with 510, 570 and 480 K Curie points and in the first one the transformation into spontaneous-polarized state at 520 K takes place.

Kosse, L.I.; Politova, E.D.; Chechkin, V.V.; Myzgin, E.A.; Medvedev, B.S.; Venevtsevae, Yu.N. (Nauchno-Issledovatel' skij Fiziko-Khimicheskij Inst., Moscow (USSR))

1982-11-01

145

Fine-structure constant constraints on Bekenstein-type models  

CERN Document Server

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

Leal, P M M; Ventura, L B

2014-01-01

146

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

147

The structure and dynamics of bubble-type vortex breakdown  

Science.gov (United States)

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

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

1990-01-01

148

Fine structure of cell types in an ameloblastoma.  

Science.gov (United States)

An unusually large and old ameloblastoma, which revealed a diverse histological appearance, was studied by light and electron microscopy. In the tumor, the epithelial component formed several patterns in the collagenous stroma. The epithelial islands, consisting of tall columnar cells surrounding the inner core of stellate cells, mimicked the cells of the inner enamel epithelium and stellate reticulum, respectively, of the normal enamel organ. The ultrastructural appearances of the columnar cells, however, were only similar to those which are seen in undifferentiated preameloblasts. Areas of squamous metaplasia were present, and these squamous cells were structurally similar to the cells at the base of the oral epithelium. Some epithelial cells containing numerous lipid granules and mitochondria formed a network of cords. The connective tissue stroma was made up of fibroblast-like cells which appear to be metabolically active. In addition, multinucleated giant cells were present in the connective tissue stroma near the epithelial component. PMID:120429

Kim, S K; Nasjleti, C E; Weatherbee, L

1979-12-01

149

The Mathematical Structure of Theories of Semigeostrophic Type  

Science.gov (United States)

In the past twenty years, semigeostrophic equations have become a prominent model for describing certain atmospheric motions on a synoptic scale, including the presence of fronts. Theoretical studies of them have revealed Hamiltonian features, and novel numerical methods, motivated by the need to improve weather forecasts, have been explored. A shallow-water theory analogue has been used as a paradigm for some aspects. This paper sets out to uncover the mathematical structure of the semigeostrophic equations that has been essential to finding solutions and developing numerical techniques. We study the shallow-water and atmospheric theories side-by-side, and we introduce a generalized form which encapsulates the differences between them. When the Coriolis parameter, f, is a constant, it is found that a lift transformation is at the heart of the theory, and the consequences of this are developed. When f is not a constant, the role of the lift transformation is, in some respects, looser; we explore the extent to which it still offers a worthwhile guide. In particular, it can be viewed as motivating a generalization of the geostrophic momentum transformation for planetary semigeostrophic equations. The paper is broadly self-contained, and it takes account of several different strands in the existing literature.

Roulstone, I.; Sewell, M. J.

1997-12-01

150

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

In order to survive under extremely cold environments, many organisms produce antifreeze proteins (AFPs). AFPs inhibit the growth of ice crystals and protect organisms from freezing damage. Fish AFPs can be classified into five distinct types based on their structures. Here we report the structure of herring AFP (hAFP), a Ca2+-dependent fish type II AFP. It exhibits a fold similar to the C-type (Ca2+-dependent) lectins with unique ice-binding features. The 1.7 Å crystal structure of hAFP wit...

2007-01-01

151

A study of plume rise from multi-tube chimney and types of chimney structure  

Energy Technology Data Exchange (ETDEWEB)

This paper tries to determine the most economical type of reinforced concrete chimney structure based on the same effective height of chimney. Simulation experiments of wind tunnel were performed in the study, which compare multi-tube chimney with single tube chimney based on the same buoyancy flux of plume. According to the comparison of experiment results and the previous studies of plume rise, the paper defines some final plume rise models. Finally, the paper gives the cost-benefit analysis after making cost estimation for different types of chimney structure and recommends the economical and reasonable type of chimney structure in light of the same environmental benefits. 7 tabs.

Liu Yongjiu [Northwest Electric Power Design Institute, Xian (China)

1996-12-31

152

Structural study of the type II 3-dehydroquinate dehydratase from Actinobacillus pleuropneumoniae  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The structure of the type II dehydroquinate dehydratase (DHQase) from Actinobacillus pleuropneumoniae, the third enzyme of the shikimate pathway, has been determined. Crystals diffracting to 1.7 Å were obtained in space and on earth using the counter-diffusion technique. The structure was solved using molecular replacement and refined to high resolution. The overall structure of the dodecameric enzyme is described and compared with structures of DHQases from other bacteria. DHQases contain a...

Maes, D.; Gonza?lez-rami?rez, L. A.; Lo?pez-jaramillo, F. J.; Yu, B.; Bondt, H.; Zegers, I.; Afonina, E.; Garci?a Ruiz, Juan Manuel; Gulnik, S.

2004-01-01

153

Seismic evaluations of reactor structure for tank type-fast breeder reactor  

International Nuclear Information System (INIS)

Tank type fast breeder reactors are those of the type that the primary sodium directly cooling the core and the primary equipment such as a pump and an intermediate heat exchanger are contained in a reactor vessel of about 20 m diameter and 20 m depth. In the tank type reactors, the pressure during the operation is low, therefore, it is the structural feature that reactor vessels become large, thin-walled shells, and consequently, the development of the techniques for evaluating the aseismatic soundness of reactor structures seems to be one of the important technical subjects. In this paper, the techniques of analyzing the earthquake response for carrying out the aseismatic design of tank type fast breeder reactors and the techniques of evaluating buckling behavior are reported about their state of development. Moreover, it is discussed that as the results of having applied these evaluating techniques to the structure of tank type fast breeder reactors, the prospect that the structure is usable under the severe condition of aseismatic design in Japan was obtained. In the structure of tank type reactors, the strength reliability against thermal stress using a thin-walled structure and the aseismatic reliability using a thick-walled structure must be compatible. (Kako, I.)

1985-01-01

154

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-03-08

155

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

156

Crystal structure of Zebrafish interferons I and II reveals conservation of type I interferon structure in vertebrates.  

Science.gov (United States)

Interferons (IFNs) play a major role in orchestrating the innate immune response toward viruses in vertebrates, and their defining characteristic is their ability to induce an antiviral state in responsive cells. Interferons have been reported in a multitude of species, from bony fish to mammals. However, our current knowledge about the molecular function of fish IFNs as well as their evolutionary relationship to tetrapod IFNs is limited. Here we establish the three-dimensional (3D) structure of zebrafish IFN?1 and IFN?2 by crystallography. These high-resolution structures offer the first structural insight into fish cytokines. Tetrapods possess two types of IFNs that play an immediate antiviral role: type I IFNs (e.g., alpha interferon [IFN-?] and beta interferon [IFN-?]) and type III IFNs (lambda interferon [IFN-?]), and each type is characterized by its specific receptor usage. Similarly, two groups of antiviral IFNs with distinct receptors exist in fish, including zebrafish. IFN?1 and IFN?2 represent group I and group II IFNs, respectively. Nevertheless, both structures reported here reveal a characteristic type I IFN architecture with a straight F helix, as opposed to the remaining class II cytokines, including IFN-?, where helix F contains a characteristic bend. Phylogenetic trees derived from structure-guided multiple alignments confirmed that both groups of fish IFNs are evolutionarily closer to type I than to type III tetrapod IFNs. Thus, these fish IFNs belong to the type I IFN family. Our results also imply that a dual antiviral IFN system has arisen twice during vertebrate evolution. PMID:21653665

Hamming, Ole Jensen; Lutfalla, Georges; Levraud, Jean-Pierre; Hartmann, Rune

2011-08-01

157

Crosstie Overlay Slow-Wave Structure for Broadbrand Traveling-Wave Type Electro-Optical Modulators,  

Science.gov (United States)

In this paper, a new crosstie overlay slow-wave structure is proposed for wideband traveling-wave type optical modulators. The simultaneous matching of phase velocity and impedance has been successfully achieved through the numerical analysis of the slow-...

H.-Y. Lee T. H. Wang T. Itoh

1988-01-01

158

New compounds with type Th2Zn17 structure in REM-Al-Cu systems  

International Nuclear Information System (INIS)

New compounds R2Al10Cu7 (where R: Sm, Gd, Tb, Dy, Ho, Er) are obtained. Using the method of X-ray diffraction analysis their crystal structure, belonging to Th2Z17 type, is determined. The change of lattice periods and unit cell volume of compounds with the structure of Th2Zn17 type depending on the ordinal number of rare earth metal is considered

1982-01-01

159

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

CERN Document Server

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

160

Meridional electric fields in layer-type and clump-type plasma structures in midlatitude sporadic E region: Observations and plausible mechanisms  

Science.gov (United States)

use of multibased line interferometry technique operated by a VHF coherent scatter radar with relatively broad radar beam pattern makes it possible to reveal zonal drift velocity of 3 m field-aligned irregularities (FAIs) inside moving layer-type or clump-type plasma structures at kilometer scale. We present compelling evidences in this article showing that, no matter what types of the plasma structures, the apparent zonal drift velocity of the 3 m FAIs is always linearly dependent on the zonal trace velocity (or bulk velocity) of the kilometer-scale plasma structure. This feature seems to imply that the bulk motion of the large-scale plasma structure may significantly affect the observed 3 m FAI Doppler velocity, which should be removed to obtain true FAI drift velocity. In addition, there is an evident tendency for the 3 m FAIs in the layer-type plasma structure to drift in the same zonal direction as the moving plasma structure. However, the correlation between the drift direction of the 3 m FAIs and the moving direction of the large-scale plasma structure is indistinct for the clump-type plasma structure. The meridional electric fields estimated from the true zonal FAI drift velocities for the layer-type plasma structures moving in the west (east) direction point in the northward/upward (southward/downward) direction. Statistical results show that the mean value of the meridional electric field inside the layer-type plasma structure is approximately 2.7-2.8 mV/m, about one order of magnitude larger than that for the clump-type plasma structure. Mechanisms that are, respectively, responsible for the generations of the layer-type and clump-type plasma structures are discussed in this article. It is believed that neutral wind shear is very likely the main cause of the layer-type plasma structure formation, while the clump-type plasma structure may be associated with propagating gravity wave.

Chu, Y. H.; Yang, K. F.; Wang, C. Y.; Su, C. L.

2013-03-01

 
 
 
 
161

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

Directory of Open Access Journals (Sweden)

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

Wilcox Elizabeth

2006-07-01

162

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

Directory of Open Access Journals (Sweden)

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

Changsung Kim

2012-08-01

163

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Plasminogen activator inhibitor-1 (PAI-1), together with its physiological target urokinase-type plasminogen activator (uPA), plays a pivotal role in fibrinolysis, cell migration, and tissue remodeling and is currently recognized as being among the most extensively validated biological prognostic factors in several cancer types. PAI-1 specifically and rapidly inhibits uPA and tissue-type PA (tPA). Despite extensive structural/functional studies on these two reactions, the underlying structura...

2011-01-01

164

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

Directory of Open Access Journals (Sweden)

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

O.R. Nandagopan

2013-07-01

165

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

Energy Technology Data Exchange (ETDEWEB)

In this communication we report the detailed crystal structure of two polymorphs of ThGeO{sub 4} (scheelite and zircon type) by Rietveld refinement of the neutron diffraction data of polycrystalline samples. Both of crystal structures consist of ThO{sub 8} (bisdisphenoid) and GeO{sub 4} tetrahedra. Scheelite type structure is a meta-stable polymorph and densely packed lattice, with a little larger average bond lengths of Th-O and Ge-O bonds to accommodate better packing. This is responsible for zircon to scheelite transformation under pressure. However, the average anion-anion contact and cation-cation contacts are shorter in scheelite structure compared to the zircon structure, which would causes the meta-stability in the scheelite structure.

Achary, S.N. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India)]. E-mail: sachary@apsara.barc.ernet.in; Patwe, S.J. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Krishna, P.S.R. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Sindhe, A.B. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India)]. E-mail: aktyagi@magnum.barc.ernet.in

2007-07-12

166

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 le...

Joongu Kang; Changsung Kim; Sanghwa Jung; Hongkoo Yeo

2012-01-01

167

Structure of an archaeal-type phosphoenolpyruvate carboxylase sensitive to inhibition by aspartate  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The crystal structure of an archaeal-type phosphoenolpyruvate carboxylase from Clostridium perfringens has been determined based on X-ray data extending to 3 ?. The asymmetric unit of the structure includes two tetramers (each a dimer-of-dimers) of the enzyme. The precipitant, malonate, employed for the crystallization is itself a weak inhibitor of phosphoenolpyruvate carboxylase and a malonate molecule is seen in the active-site in the crystal structure. The allosteric binding sites for asp...

Dharmarajan, Lakshmi; Kraszewski, Jessica L.; Mukhopadhyay, Biswarup; Dunten, Pete W.

2011-01-01

168

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

International Nuclear Information System (INIS)

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

1989-11-03

169

Structure integrity analysis of Type III iodine absorber of active carbon  

International Nuclear Information System (INIS)

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

2012-03-01

170

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2007-09-15

171

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

International Nuclear Information System (INIS)

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

2007-01-01

172

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

173

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

174

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

Directory of Open Access Journals (Sweden)

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

Nenadovi? Aleksandra

2010-01-01

175

Electronic structures of p-type doped CuInS{sub 2}  

Energy Technology Data Exchange (ETDEWEB)

The authors have studied the electronic structures of CuIn(S{sub 0.875}X{sub 0.125}){sub 2} (X = B, C, N, Si or P) based on the ab-initio electronic band structure calculations using the augmented spherical wave (ASW) method. They have clarified that the physical characteristics of the p-type doped CuInS{sub 2} crystals are mainly determined by a change in the strength of interactions between Cu and S atoms. On the basis of the calculated results, the authors discussed the material design considerations, such as controlling the strength of resistivity for p-type doped CuInS{sub 2} materials and converting the conduction type, from n-type to p-type by a codoping method.

Yamamoto, T. [Osaka Univ., Ibaraki (Japan)]|[Asahi Chemical Industry Co., Ltd., Fuji (Japan); Katayama-Yoshida, H. [Osaka Univ., Ibaraki (Japan)

1996-12-31

176

The E^3/Z3 orbifold, mirror symmetry, and Hodge structures of Calabi-Yau type  

CERN Document Server

Starting from the K\\"ahler moduli space of the rigid orbifold Z=E^3/\\mathbb{Z}_3 one would expect for the cohomology of the generalized mirror to be a Hodge structure of Calabi-Yau type (1,9,9,1). We show that such a structure arises in a natural way from rational Hodge structures on \\Lambda^3 \\mathbb{K}^6, \\mathbb{K}=\\mathbb{Q}[\\omega], where \\omega is a primitive third root of unity. We do not try to identify an underlying geometry, but we show how special geometry arises in our abstract construction. We also show how such Hodge structure can be recovered as a polarized substructure of a bigger Hodge structure given by the third cohomology group of a six-dimensional Abelian variety of Weil type.

Cacciatori, Sergio Luigi

2012-01-01

177

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

Directory of Open Access Journals (Sweden)

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

Anggie Angeline

2009-01-01

178

Building block organisation of clusters in amylopectin from different structural types.  

Science.gov (United States)

Clusters of chains consisting of tightly branched units of building blocks were isolated from 10 amylopectin samples possessing the 4 types of amylopectin with different internal unit chain profiles previously described. It was shown that clusters in types 1 and 2 amylopectins are larger than in types 3 and 4, but the average cluster size did not correspond to the ratio of short to long chains of the amylopectins. The size-distribution of the building blocks, having one or several branches, possessed generally only small differences between samples. However, the length of the interblock segments followed the type of amylopectin structure, so that type 1 amylopectins had shortest and type 4 the longest segments. The chains in the clusters were divided into characteristic groups probably being involved in the interconnection of two, three, and four - or more - building blocks. Long chains were typically found in high amounts in clusters from type 4 amylopectins, however, all cluster samples contained long chains. The results are discussed in terms of the building block structure of amylopectin, in which the blocks together with the interblock segments participate in a branched backbone building up the amorphous lamellae inside growth rings of the starch granules. In such a model, amylopectins with proportionally less long chains (types 1 and 2) possess a more extensively branched backbone compared to those with more long chains (types 3 and 4). PMID:22465108

Bertoft, Eric; Koch, Kristine; Aman, Per

2012-06-01

179

Comparative study of fine structure in samples of isolated and paired early-type galaxies  

Science.gov (United States)

Fine structure in early-type galaxies is considered to be among the more robust indicators of a past merging or acquisition event, although growing evidence from numerical simulations suggests that fine structure may be also interpreted in a `weak interaction' framework. We present a morphological study of a sample composed of 61 `isolated' early-type galaxies addressed to the detection of fine structure. This sample has been selected in order to be statistically comparable to a set of 54 early-type galaxies, members of pairs analysed by Reduzzi & Rampazzo with a similar technique. The rate of occurrence of fine structure detected in the `isolated' galaxy sample is significantly higher than that found for the pairs. In particular, the fraction of isolated early-type galaxies exhibiting shells is 16.4 per cent, a percentage similar to that found by Malin & Carter for RC2 isolated objects in the southern sky, while the fraction of early-type galaxies in pairs is ~=4 per cent. We discuss the comparison between the two samples in the context of the merger versus the weak interaction origin of fine structures. Concerning the formation of shells, although the merger origin cannot be ruled out, the observed difference is more naturally explained within the weak interaction framework.

Reduzzi, L.; Longhetti, M.; Rampazzo, R.

1996-09-01

180

In Situ D-periodic Molecular Structure of Type II Collagen  

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-05-06

 
 
 
 
181

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

International Nuclear Information System (INIS)

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

1985-01-01

182

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

International Nuclear Information System (INIS)

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

1997-01-01

183

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

Energy Technology Data Exchange (ETDEWEB)

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

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

1997-01-15

184

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

International Nuclear Information System (INIS)

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

2007-03-01

185

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

CERN Document Server

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

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

2007-01-01

186

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

187

Likelihood Ratio Type Test and its Critical Values for Structural Change of Unknown Changepoint  

Digital Repository Infrastructure Vision for European Research (DRIVER)

This study considers the problem of testing for a structural change of unknown timing in a regression coefficient in the linear regression model. This is a non-standard testing problem and practical important situation facing applied modelers. Simulation methods were used to generate a range of exact critical values of the Likelihood Ratio (LR) type test for different sample sizes, numbers of regressors and types of regressors. We found that the critical values depend on sample size, the numb...

Mohammad Nurul Azam; Mahbuba Yeasmin; Gazi Mahabubul Alam

2013-01-01

188

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

2005-01-01

189

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 fo...

2009-01-01

190

Equivalent linearization method for limit cycle flutter analysis of plate-type structure in axial flow  

International Nuclear Information System (INIS)

The responses and limit cycle flutter of a plate-type structure with cubic stiffness in viscous flow were studied. The continuous system was dispersed by utilizing Galerkin Method. The equivalent linearization concept was performed to predict the ranges of limit cycle flutter velocities. The coupled map of flutter amplitude-equivalent linear stiffness-critical velocity was used to analyze the stability of limit cycle flutter. The theoretical results agree well with the results of numerical integration, which indicates that the equivalent linearization concept is available to the analysis of limit cycle flutter of plate-type structure. (authors)

2009-06-01

191

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2008-01-01

192

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Banks are important financial intermediaries of any national economy, and corporate governance has an important role in banking sector; especially due to processes of the globalization and the internationalization, and also because of the sensitivity of the activities between the interest groups. The objective of this paper is to examine the relationship between ownership structure, concentration, owners’ type and bank performance. The authors made a research of banks' ownership structure u...

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

2012-01-01

193

Resonant intrinsic spin hall effect in p-type GaAs quantum well structure.  

Science.gov (United States)

We study intrinsic spin Hall effect in p-type GaAs quantum well structure described by Luttinger Hamiltonian and a Rashba spin-orbit coupling arising from the structural inversion symmetry breaking. The Rashba term induces an energy level crossing in the lowest heavy hole subband, which gives rise to a resonant spin Hall conductance. The resonance may be used to identify the intrinsic spin Hall effect in experiments. PMID:16606211

Dai, Xi; Fang, Zhong; Yao, Yu-Gui; Zhang, Fu-Chun

2006-03-01

194

Resonant intrinsic spin Hall effect in p-type GaAs quantum well structure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We study intrinsic spin Hall effect in p-type GaAs quantum well structure described by Luttinger Hamiltonian and a Rashba spin-orbit coupling arising from the structural inversion symmetry breaking. The Rashba term induces an energy level crossing in the lowest heavy hole subband, which gives rise to a resonant spin Hall conductance. The resonance may be used to identify the intrinsic spin Hall effect in experiments.

Dai, Xi; Fang, Zhong; Yao, Yu-gui; Zhang, Fu-chun

2005-01-01

195

Structure and Interactions of Fish Type III Antifreeze Protein in Solution  

Digital Repository Infrastructure Vision for European Research (DRIVER)

It has been suggested that above a critical protein concentration, fish Type III antifreeze protein (AFP III) self-assembles to form micelle-like structures that may play a key role in antifreeze activity. To understand the complex activity of AFP III, a comprehensive description of its association state and structural organization in solution is necessary. We used analytical ultracentrifugation, analytical size-exclusion chromatography, and dynamic light scattering to characterize the intera...

2010-01-01

196

Predicting structures and stabilities for H-type pseudoknots with interhelix loops  

Digital Repository Infrastructure Vision for European Research (DRIVER)

RNA pseudoknots play a critical role in RNA-related biology from the assembly of ribosome to the regulation of viral gene expression. A predictive model for pseudoknot structure and stability is essential for understanding and designing RNA structure and function. A previous statistical mechanical theory allows us to treat canonical H-type RNA pseudoknots that contain no intervening loop between the helices (see S. Cao and S.J. Chen [2006] in Nucleic Acids Research, Vol. 34; pp. 2634–2652)....

2009-01-01

197

Structural variations in ?-type Al-Pd-(Mn, Fe) complex metallic alloy phases  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Structural modifications in complex metallic ?-Al-Pd-(Mn, Fe) samples are studied by means of transmission electron microscopy. The modifications were observed in the vicinity of metadislocations and at phase boundaries. They are determined by the density and inclination of phason planes. In the vicinity of metadislocations and at an ?6-?28-phase boundary, new monoclinic ?-type structures appear locally, which were not detected as bulk phases in...

2008-01-01

198

Type VI secretion requires a dynamic contractile phage tail-like structure  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type VI Secretion Systems (T6SS) are bacterial virulence-associated nanomachines composed of proteins that are evolutionarily related to components of bacteriophage tails. Here we show that protein secretion by the T6SS of Vibrio cholerae requires the action of a dynamic intracellular tubular structure that is structurally and functionally homologous to contractile phage tail sheath. Time-lapse fluorescence light microscopy revealed that T6SS sheaths cycle between assembly, quick contraction,...

Basler, M.; Pilhofer, M.; Henderson, P. G.; Jensen, J. G.; Mekalanos, J.

2012-01-01

199

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

The biosynthetic shikimate pathway consists of seven enzymes that catalyze sequential reactions to generate chorismate, a critical branch point in the synthesis of the aromatic amino acids. The third enzyme in the pathway, dehydroquinate dehydratase (DHQD), catalyzes the dehydration of 3-dehydroquinate to 3-dehydroshikimate. We present three crystal structures of the type I DHQD from the intestinal pathogens Clostridium difficile and Salmonella enterica. Structures of the enzyme with substrat...

Light, Samuel H.; Minasov, George; Shuvalova, Ludmilla; Duban, Mark-eugene; Caffrey, Michael; Anderson, Wayne F.; Lavie, Arnon

2011-01-01

200

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

 
 
 
 
201

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

Science.gov (United States)

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

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

2014-01-01

202

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

Science.gov (United States)

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

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

1997-12-01

203

Types of convergent margins and structural and metamorphic patterns of accretionary prisms  

Energy Technology Data Exchange (ETDEWEB)

Theoretical modeling of the subduction channel (shear zone) at convergent plate margins quantifies the processes of sediment subduction, offscraping, underplating and formation of subduction melange by upwelling. Although bedding anisotropy and variations in lithology and pore-fluid pressure control the details of the deformation near the inlet to the subduction channel, the theory shows there are only five basic kinematic patterns which can result in the development of a distinctive type of margin (Types A-E). All incoming sediment is subducted and subduction erosion can occur at Type A margins. All sediment is subducted but a thick, narrow accretionary prism grows by underplating of subducted sediment at Type B margins. Offscraping leads to the development of a broad, tapering prism at Type C, D, and E margins. Incoming sediment is offscraped and subducted sediment is underplated at Type C margins. Melange upwells from depth and is offscraped and underplated at Type D and E margins. Incoming sediment is also offscraped at Type D margins. The structural and metamorphic histories of the fundamental tectonostratigraphic units within the accretionary prism are distinct during steady-state subduction. The bedded slope cover is not metamorphosed and not intensely tectonized upslope from the inlet. During final dewatering and accretion, offscraped materials undergo a subhorizontally-directed compression whereas underplated materials undergo a simple-shear-style of deformation. The metamorphic changes in subducted sediment or upwelled melange depend upon the depth of maximum burial and the thermal structure of the margin. Various episodic factors, such as seamount or ridge subduction, can modify the structural and metamorphic contrasts.

Cloos, M.; Shreve, R.L.

1985-01-01

204

Microscopic Structure of the Mach-Type Reflection of Weak Shock Waves.  

Science.gov (United States)

The purpose of the present work was to investigate the microscopic structure of the three-shock interaction region generated in a low-density shock tube during the Mach-type reflection of a weak shock wave. The experimental conditions corresponded to the ...

Z. A. Walenta

1981-01-01

205

The neurobiological basis of Neurofibromatosis type I: new insights into brain structure, function and neurochemistry  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Neurofibromatosis type 1 (NF1) is a single-gene disorder associated with complex cognitive dysfunction including learning disabilities, attention deficit hyperactive disorder, executive function, visuospatial and motor coordination deficits. Neuroimaging techniques can contribute to identify the neurobiological basis underlying these impairments. Here, I used spectroscopy, functional and structural brain imaging to identify the neural and neurotransmitter systems involved in the aetiology of ...

Violante, Ine?s Ribeiro

2012-01-01

206

Determining biholomorphic type of a manifold using combinatorial and algebraic structures  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We settle two problems of reconstructing a biholomorphic type of a manifold. In the first problem we use graphs associated to Riemann surfaces of a particular class. In the second one we use the semigroup structure of analytic endomorphisms of domains in $\\C^n$.

Merenkov, Sergei

2013-01-01

207

Transport properties of RInCu_4 with C15b-type structure  

International Nuclear Information System (INIS)

The electrical resistivity and thermoelectric power were measured for RInCu_4 (R=Y and heavy rare earth) with the cubic C15-type crystal structure. The results are explained assuming a semimetallic band picture for the RInCu_4 system. ((orig.))

1995-02-09

208

Tate twists of Hodge structures arising from abelian varieties of type IV  

CERN Multimedia

We show that certain abelian varieties A have the property that for every Hodge structure V in the cohomology of A, every effective Tate twist of V occurs in the cohomology of some abelian variety. We deduce the general Hodge conjecture for certain non-simple abelian varieties of type IV.

Abdulali, Salman

2012-01-01

209

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

International Nuclear Information System (INIS)

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

2012-11-01

210

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-11-01

211

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

Science.gov (United States)

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

Lin, Qingsong; Kosinski, Jan; Seetharaman, J.; Bujnicki, Janusz M.; Sivaraman, J.; Hew, Choy-Leong

2007-01-01

212

Perturbation method of analyzing mode localization of asymmetrical plate-type structure in incompressible flows  

International Nuclear Information System (INIS)

The dynamical characteristics of a simple two-span parallel flat plate-type model vibrating in incompressible water are studied here. The assumption mode method is used to form the motion equation of the structure. By using a second order perturbation method, the great emphasis is focused on the influences of the asymmetrical parameter of the structure, the deviation of length and stiffness of the torsional spring on the degrees of mode localization of the structure. The results show that the second method can be applied to predict the dynamical characteristics of the structure accurately. The influences of the coupling effect of the fluid on the phenomena of the two piece beams' mode localization are different. The asymmetrical parameter of length is the main factor that leads to the behaviors of mode localization of the structure. The deviation of stiffness of the torsional spring, too, has significant influences on the phenomena of mode localization

2002-06-01

213

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

Directory of Open Access Journals (Sweden)

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

Igor Tomi?i?

2012-12-01

214

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

215

Thermodynamics and vacancy ordering in titanium-tellurium alloys with NiAs type crystal structures  

Energy Technology Data Exchange (ETDEWEB)

Tellurium vapor pressures were determined by an isopiestic method for solid titanium-tellurium alloys with NiAs-derivative crystal structures between 55 and 66.7 at.% Te and between 825 and 1350 K. Activities and partial molar enthalpies of tellurium were derived from them. The results are interpreted in terms of a statistical theoretical model, based on a Cr[sub 3]S[sub 4] type superstructure (with a certain ordering pattern of titanium vacancies) for Ti[sub 3]Te[sub 4]. The model curve describing the experimental activity data is compatible with the assumption of a continuous transition from the Cr[sub 3]S[sub 4] type superstructure (at 57.1 at.% Te) through the V[sub 5]Se[sub 8] type superstructure (at 61.5 at.% Te) to the CdI[sub 2] structure (at 66.7 at.% Te). (orig.)

Ipser, H. (Institut fuer Anorganische Chemie, Vienna Univ. (Austria)); Krachler, R. (Institut fuer Anorganische Chemie, Vienna Univ. (Austria))

1993-09-01

216

Thermodynamics and vacancy ordering in titanium-tellurium alloys with NiAs type crystal structures  

International Nuclear Information System (INIS)

Tellurium vapor pressures were determined by an isopiestic method for solid titanium-tellurium alloys with NiAs-derivative crystal structures between 55 and 66.7 at.% Te and between 825 and 1350 K. Activities and partial molar enthalpies of tellurium were derived from them. The results are interpreted in terms of a statistical theoretical model, based on a Cr3S4 type superstructure (with a certain ordering pattern of titanium vacancies) for Ti3Te4. The model curve describing the experimental activity data is compatible with the assumption of a continuous transition from the Cr3S4 type superstructure (at 57.1 at.% Te) through the V5Se8 type superstructure (at 61.5 at.% Te) to the CdI2 structure (at 66.7 at.% Te). (orig.)

1993-09-01

217

Potent anti-HIV (type 1 and type 2) activity of polyoxometalates: structure-activity relationship and mechanism of action.  

Science.gov (United States)

A series of polyoxometalates have been synthesized and evaluated for their inhibitory effects on HIV-1(III(B)) and HIV-1(ROD) replication in MT-4 cells. All compounds showed activity against HIV-1 and HIV-2, but the antiviral potency of the heteropolytungstates varied considerably depending on their chemical structure. The antiviral activity of single, double, and triple Keggin-type of compounds against HIV-1(III(B)) replication was comparable (IC(50): 0.4-0.5 microgram/mL), whereas HIV-2(ROD) appeared to become less sensitive with the increasing number of Keggin structures per compound. The same trend was observed for single and double Dawson structures. Some of these compounds were examined for their inhibitory effect on the replication of HIV-1(RF) and SIV(MAC(251)) in MT-4 cells. Their anti-HIV-1(RF) and anti-SIV(MAC(251)) potencies were comparable to those for the HIV-1(III(B)) or HIV-2(ROD) strain, respectively. The polyoxometalates represent a class of polyanionic compounds, which block the binding of the envelope glycoprotein gp120 of HIV to CD4(+) cells. The compounds interfered with the binding of anti-CD4 mAb to the OKT4A/Leu3a epitope of the CD4 receptor, compound 24 being the most active in this regard, and inhibited the binding of anti-gp120 mAb to infected MT-4 cells. None of the polyoxometalates inhibited the binding of a specific CXCR4 mAb to SUP-T1 cells, suggesting that they do not interact with CXCR4, the main co-receptor for T-tropic HIV strains, and thus act as virus binding, and not as fusion, inhibitors. PMID:10715146

Witvrouw, M; Weigold, H; Pannecouque, C; Schols, D; De Clercq, E; Holan, G

2000-03-01

218

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-02-27

219

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

Science.gov (United States)

We studied the use of song types and their acoustic features in different social contexts in the banded wren (Thryothorus pleurostictus), a resident tropical songbird in which males possess about 20 distinctive song types varying in duration, bandwidth, note composition, and trill structure. We recorded six focal males intensively for four days each while we observed context information such as during versus after dawn chorus, presence of the female, counter-versus solo-singing, location at the edge versus centre of the territory, and proximity to the nest. All males used at least some song types differentially during each of these pairs of alternative contexts. Males also preferentially used the song types they shared with a given neighbour when interacting with that bird. Songs delivered during dawn chorus were significantly longer, wider in bandwidth, often compound (double songs), and more likely to contain a rattle or buzz and an up-sweeping trill, compared to songs delivered after dawn chorus. Similar features were also more commonly observed when birds were engaged in intense male-male interactions and boundary disputes after dawn chorus, especially when countersinging at the edge of the territory. The presence of the female caused the male to deliver song types with narrower whole-song and trill bandwidth and fewer rattles and buzzes, and song-type diversity and fraction of compound songs were higher when the female was present. Thus, in addition to using type matching and variations in song-type switching and diversity to signal different levels of aggressive intention, male banded wrens also select song types based on their acoustic structure in different social contexts. PMID:17173097

Trillo, P A; Vehrencamp, S L

2005-10-01

220

Visualization and Analyses of Jet Structures from a Cluster-Type Linear Aerospike Nozzle  

Science.gov (United States)

Aerospike nozzles have been expected as a candidate for an engine of reusable space shuttles to respond to growing demand for rocket-launching and its cost reduction. In this study, the flow field structure in any cross sections around the linear-type aerospike nozzle are visualized and analyzed, using laser induced fluorescence (LIF) of NO seeded in the carrier gas N2. Since the flow field structure is affected mainly by the pressure ratio (P/P), the linear-type aerospike nozzle is set inside the vacuum chamber to carry out the experiments in the wide range of pressure ratios from 75 to 250. Flow fields are visualized in several cross-sections, demonstrating the complicated three-dimensional flow field structures. Pressure sensitive paint (PSP) of PtTFPP bound by poly(TMSP) is also applied successfully to measurement of the complicated pressure distribution on the spike surface.

Niimi, Tomohide; Mori, Hideo; Okabe, Kazuki; Masai, Yusuke; Taniguchi, Mashio

 
 
 
 
221

In and out of the cation pumps: P-type ATPase structure revisited.  

DEFF Research Database (Denmark)

Active transport across membranes is a crucial requirement for life. P-type ATPases build up electrochemical gradients at the expense of ATP by forming and splitting a covalent phosphoenzyme intermediate, coupled to conformational changes in the transmembrane section where the ions are translocated. The marked increment during the last three years in the number of crystal structures of P-type ATPases has greatly improved our understanding of the similarities and differences of pumps with different ion specificities, since the structures of the Ca2+-ATPase, the Na+,K+-ATPase and the H+-ATPase can now be compared directly. Mechanisms for ion gating, charge neutralization and backflow prevention are starting to emerge from comparative structural analysis; and in combination with functional studies of mutated pumps this provides a framework for speculating on how the ions are bound and released as well as on how specificity is achieved.

Bublitz, Maike; Poulsen, Hanne

2010-01-01

222

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

CERN Multimedia

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

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

2010-01-01

223

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

Energy Technology Data Exchange (ETDEWEB)

Highlights: Black-Right-Pointing-Pointer A new structure type with the composition Sc{sub 4}Fe{sub 5}Ge{sub 6.10(3)}Sn{sub 1.47(2)}. Black-Right-Pointing-Pointer Crystallizes in the space group Immm (No. 71, oI144). Black-Right-Pointing-Pointer Sample obtained using a reactive Sn flux. Black-Right-Pointing-Pointer Electronic structure calculations indicate polar intermetallic bonding network. - Abstract: A new structure type has been discovered in the system Sc-Fe-Ge-Sn by employing Sn as a flux medium. According to single crystal X-ray diffraction, the new structure has a composition of Sc{sub 4}Fe{sub 5}Ge{sub 6.10(3)}Sn{sub 1.47(2)} and crystallizes in the space group Immm (No. 71, oI144) with lattice parameters of a = 5.230(1) A, b = 13.467(3) A, and c = 30.003(6) A. The structure is composed of square anti-prismatic clusters that are condensed into zig-zag chains along the [0 1 0] direction. These chains are further condensed through a split Sn/Ge position, forming a three-dimensional network. Magnetization measurements indicate an antiferromagnetic phase transition near 240 K. Electronic structure calculations identified the most favorable bonding network in this new system. Using crystal orbital Hamilton population (COHP) curves and their integrated values (ICOHP), a polar intermetallic bonding network involving Sc-Ge as well as Fe-Sn and Fe-Ge contacts can be assigned to this new structure type.

Brgoch, Jakoah [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Ran, Sheng [Ames Laboratory, US Department of Energy, Ames, IA 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Thimmaiah, Srinivasa [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Ames Laboratory, US Department of Energy, Ames, IA 50011 (United States); Canfield, Paul C. [Ames Laboratory, US Department of Energy, Ames, IA 50011 (United States); Department of Physics and Astronomy, Iowa State University, Ames, IA 50011 (United States); Miller, Gordon J., E-mail: gmiller@iastate.edu [Department of Chemistry, Iowa State University, Ames, IA 50011 (United States); Ames Laboratory, US Department of Energy, Ames, IA 50011 (United States)

2013-01-05

224

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

Science.gov (United States)

When soil structure varies in different soil types and the horizons of these soil types, it has a significant impact on water flow and contaminant transport in soils. This paper focuses on the effect of soil structure variations on the transport of pesticides in the soil above the water table. Transport of a pesticide (chlorotoluron) initially applied on soil columns taken from various horizons of three different soil types (Haplic Luvisol, Greyic Phaeozem and Haplic Cambisol) was studied using two scenarios of ponding infiltration. The highest infiltration rate and pesticide mobility were observed for the Bt(1) horizon of Haplic Luvisol that exhibited a well-developed prismatic structure. The lowest infiltration rate was measured for the Bw horizon of Haplic Cambisol, which had a poorly developed soil structure and a low fraction of large capillary pores and gravitational pores. Water infiltration rates were reduced during the experiments by a soil structure breakdown, swelling of clay and/or air entrapped in soil samples. The largest soil structure breakdown and infiltration decrease was observed for the Ap horizon of Haplic Luvisol due to the low aggregate stability of the initially well-aggregated soil. Single-porosity and dual-permeability (with matrix and macropore domains) flow models in HYDRUS-1D were used to estimate soil hydraulic parameters via numerical inversion using data from the first infiltration experiment. A fraction of the macropore domain in the dual-permeability model was estimated using the micro-morphological images. Final soil hydraulic parameters determined using the single-porosity and dual-permeability models were subsequently used to optimize solute transport parameters. To improve numerical inversion results, the two-site sorption model was also applied. Although structural changes observed during the experiment affected water flow and solute transport, the dual-permeability model together with the two-site sorption model proved to be able to approximate experimental data. PMID:19062128

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

2009-02-16

225

Catalytic oxidation of methanol on Pt/X (X = CaTP, NaTP electrodes in sulfuric acid solution  

Directory of Open Access Journals (Sweden)

Full Text Available In this paper, we report the synthesis and characterization of electrodes based on NASICON type phosphates. The study of the electrochemical oxidation of methanol at ambient temperature on electrodes based on NASICON type Ca0,5Ti2(PO43 (CaTP and Na5Ti(PO43 (NaTP compared to that of the platinum electrode model has been conducted by cyclic voltammetry in acidic medium. The results showed a significant increase of current density on the electro oxidation of methanol on the material developed based NASICON structure CaTP, cons deactivation of the electro oxidation is observed the closed structure type NaTP.

Said Benmokhtar

2013-10-01

226

High-pressure structural investigation of several zircon-type orthovanadates  

CERN Document Server

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

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

2010-01-01

227

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

Science.gov (United States)

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

Fatmawati, Sri; Kondo, Ryuichiro; Shimizu, Kuniyoshi

2013-11-01

228

The thermodynamic and structural properties of metallocenes-type random ethylene copolymers  

Energy Technology Data Exchange (ETDEWEB)

The properties of a series of random ethylene copolymers prepared with the metallocenes catalytic system rac-Et[Ind]{sub 2} ZrCl{sub 2}/MAO were studied for a large variety of comonomer types. These include the classical 1-alkene type with length up to 10 carbons and those of the cyclic type such as cyclopentadiene and dicyclopentadiene. Under rapid crystallization, the melting temperatures of the newly synthesized copolymers followed the relation of model random copolymers indicating a behavior that conforms to that predicted by Flory's phase equilibrium theory. The molar entropy of fusion is not significantly altered by the comonomer type including the dicyclopentadiene type. All types of comonomers studied showed, for a fixed comonomer content, the same change in properties during annealing, except the ethylene 1-butenes. These latter copolymers and the hydrogenated poly butadiene showed a faster rate of change in thermal properties. This is consistent with a higher molecular diffusion for the butene comonomer than for the rest of comonomers analyzed. The properties of the inter lamellar region were also studied as a function of comonomer type and content following the variation of the amorphous halo extracted from the WAXS diffractograms. The observed systematic decrease in the peak scattering angle with increasing comonomer content indicates a variation of the intermolecular liquid structure. (author)

Simanke, Adriane G.; Mauler, Raquel S.; Galland, Griselda B. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Quimica]. E-mail: asimanke@portoweb.com.br; Alamo, Rufina G. [Florida State Univ., Tallahassee, FL (UNited States). College of Engineering. Dept. of Chemical Engineering]. E-mail: alamo@eng.fsu.edu

2001-07-01

229

The thermodynamic and structural properties of metallocenes-type random ethylene copolymers  

International Nuclear Information System (INIS)

The properties of a series of random ethylene copolymers prepared with the metallocenes catalytic system rac-Et[Ind]2 ZrCl2/MAO were studied for a large variety of comonomer types. These include the classical 1-alkene type with length up to 10 carbons and those of the cyclic type such as cyclopentadiene and dicyclopentadiene. Under rapid crystallization, the melting temperatures of the newly synthesized copolymers followed the relation of model random copolymers indicating a behavior that conforms to that predicted by Flory's phase equilibrium theory. The molar entropy of fusion is not significantly altered by the comonomer type including the dicyclopentadiene type. All types of comonomers studied showed, for a fixed comonomer content, the same change in properties during annealing, except the ethylene 1-butenes. These latter copolymers and the hydrogenated poly butadiene showed a faster rate of change in thermal properties. This is consistent with a higher molecular diffusion for the butene comonomer than for the rest of comonomers analyzed. The properties of the inter lamellar region were also studied as a function of comonomer type and content following the variation of the amorphous halo extracted from the WAXS diffractograms. The observed systematic decrease in the peak scattering angle with increasing comonomer content indicates a variation of the intermolecular liquid structure. (author)

2001-11-11

230

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

Science.gov (United States)

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

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

2014-02-15

231

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

2012-09-01

232

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

CERN Document Server

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

Kokabi, Alireza; Khorasani, Sina; Fardmanesh, Mehdi

2011-01-01

233

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

234

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-� 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 β-sheet B, and the 147-loop directly contacts PAI-1 β-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

235

Isolation and X-ray crystal structure of a securinega-type alkaloid from Phyllanthus niruri Linn.  

Science.gov (United States)

A securinega-type alkaloid epibubbialine was isolated from Phyllanthus niruri Linn. Its structure was established by spectroscopic methods and X-ray single-crystal diffraction analysis. Its crystal structure is reported herein for the first time. PMID:21878003

Zhou, Min; Zhu, Honglin; Wang, Kuiwu; Wei, Wanxing; Zhang, Yong

2012-01-01

236

Growth and structural characterization of M-type GdTaO 4 single crystal fiber  

Science.gov (United States)

The laser heated pedestal growth technique was used to obtain single crystal fiber of M-type GdTaO 4. The fibers were around 3 cm long, ?0.8 mm, transparent, colorless and did not exhibit any inclusions. The structural quality of the fibers was evaluated by X-ray rocking curve profiles and X-ray topography. Better quality crystals were grown perpendicular to (0 1 0) direction presenting rocking curve FWHM typically around 52 arcsec for the (3 2¯ 3) reflection. The results confirm that good structural fibers can be successfully obtained by the procedure presented here.

Almeida Silva, R.; Tirao, G.; Cusatis, C.; Andreeta, J. P.

2005-02-01

237

New uranium borides with the structure of YCrB4 type  

International Nuclear Information System (INIS)

The new ternary uranium borides possessing a crystal structure of the YCrB4 type; UvB4(A = 6.08q, b 11.48, C = 3.524A0), UCrB4(5.928, 11.41, 3.4.97), UFeB4(5.786, 11.41, 3.451) and UCoB4(5.865, 11.42, 3.43) have been revealed by the X-ray structural analysis. New borides UMoB4, UWB4, UReB4 and UNiB4 are not isostructural with YCrB4

1975-01-01

238

New phases RCu5Sn with the CeCu6 structure type  

International Nuclear Information System (INIS)

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

1997-11-14

239

Electronic structure in type CsCl alloys: quasizone cluster calculations  

International Nuclear Information System (INIS)

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

1982-09-01

240

UIr, a PdBi-like distorted CrB-type structure  

International Nuclear Information System (INIS)

The room temperature structure of UIr was found to be monoclinic with cell parameters a=7.271(1) A, b=10.578(2) A, c=8.511(1) A, ?=90.16(1)"0; Z=16, space group B2_1. The final residual value for 960 observed reflections was R=0.082 and 0.124 for all 1502 unique reflections. The structure of UIr is a distortion variant of the CrB type similar to that of PdBi, although there the monoclinic angle is acute. The distortions lead to bonds between adjacent iridium zigzag chains. (orig.)

1986-01-01

 
 
 
 
241

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2010-01-01

242

FY1995 research of new functional photonic devices based on type 2 quantum well structures; 1995 nendo type 2 kozo base no shingenri hikari kino device no kenkyu  

Energy Technology Data Exchange (ETDEWEB)

Quantum well photonic devices, such as high speedoptical modulators and/or optical logic devices are indispensable for future large capacity optical fiber information systems. All of these devices have been fabricated using type 1 quantum well structures. Type 2 quantum well structures, which have entirely different properties from those of type 1 quantum well structures, have a potential for new functional devices based on new operation principle. The purpose of the research is to realize new quantum well photonic devices using type 2 structures. (1) InAlAs/Inp type 2 multiple quantum well (MQW) diodes were grown by molecular beam epitaxy (MBE). A remarkable bistability was observed in the current-light output (I - L) characteristic for the first time. By measuring the temperature and structure dependence of the bistable characteristic, the mechanism was clarified. These results can be applied for new optical bistable devices. (2) The hetero-interface quality was characterized for InAlAs/InP type 2 single hetero structures. It was found that the photoluminescence (PL) intensity of the sample grown on (111)B substrates was enhanced by more than one ordercomparing with that grown on (100) substrates at room temperature. The temperature dependence, excitation power dependence, and transport troperties were studied. The results suggest that high quality hetero-interface can be grown by using (111)B substrates. (3) The InAlAs/AlAsSb type 2 MQW structure was grown by molecular beam epitaxy. Type 2 light emission was observed for the first time. The valence band discontinui was found to be 0.28 eV from the structural dependence of the emission energy. (NEDO)

NONE

1997-03-01

243

Structural analysis of 1-Cys type selenoprotein methionine sulfoxide reductase A.  

Science.gov (United States)

Methionine sulfoxide reductase A (MsrA) reduces free and protein-based methionine-S-sulfoxide to methionine. Structures of 1-Cys MsrAs lacking a resolving Cys, which interacts with catalytic Cys, are unknown. In addition, no structural information on selenocysteine (Sec)-containing MsrA enzymes has been reported. In this work, we determined the crystal structures of 1-Cys type selenoprotein MsrA from Clostridium oremlandii at 1.6-1.8Å, including the reduced, oxidized (sulfenic acid), and substrate-bound forms. The overall structure of Clostridium MsrA, consisting of ten ?-helices and six ?-strands, folds into a catalytic domain and a novel helical domain absent from other known MsrA structures. The helical domain, containing five helices, tightly interacts with the catalytic domain, and is likely critical for catalytic activity due to its association with organizing the active site. This helical domain is also conserved in several selenoprotein MsrAs. Our structural analysis reveals that the side chain length of Glu55 is critical for the proton donor function of this residue. Our structures also provide insights into the architecture of the 1-Cys MsrA active site and the roles of active site residues in substrate recognition and catalysis. PMID:24412203

Lee, Eun Hye; Kwak, Geun-Hee; Kim, Moon-Jung; Kim, Hwa-Young; Hwang, Kwang Yeon

2014-03-01

244

Crystal structures of VSn[sub 2], NbSn[sub 2] and CrSn[sub 2] with Mg[sub 2]Cu-type structure and NbSnSb with CuAl[sub 2]-type structure  

Energy Technology Data Exchange (ETDEWEB)

Several binary stannides of the early transition metals T have been reported with the composition T[sub 2]Sn[sub 3] previously. However, the present structure refinements from single-crystal X-ray data show that they have the compositions VSn[sub 2], NbSn[sub 2] and CrSn[sub 2] (R=0.028, R=0.018 and R=0.021 with 17 variable parameters and 828, 512 and 440 structure factors respectively). Their orthorhombic Mg[sub 2]Cu-type structure is closely related to the structures of MoSn[sub 2] (Mg[sub 2]Ni type) and CuAl[sub 2]. The latter structure type was confirmed for NbSnSb by a structure refinement from single-crystal data (R=0.010 for eight variables and 254 F values). Electrical conductivity measurements show CrSn[sub 2] and MoSn[sub 2] to be metallic conductors. ((orig.))

Woelpl, T. (Anorganisch-Chemisches Institut, Universitaet Muenster, Wilhelm-Klemm-Strasse 8, D-48149 Muenster (Germany)); Jeitschko, W. (Anorganisch-Chemisches Institut, Universitaet Muenster, Wilhelm-Klemm-Strasse 8, D-48149 Muenster (Germany))

1994-08-01

245

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

CERN Document Server

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

Pridham, J P

2011-01-01

246

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

Directory of Open Access Journals (Sweden)

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

O.G.Vlokh

2000-09-01

247

Heat resistant/radiation resistant cable and incore structure test device for FBR type reactor  

International Nuclear Information System (INIS)

A heat resistant/radiation resistant coaxial cable of the present invention comprises an insulation layer, an outer conductor and a protection cover in this order on an inner conductor, in which the insulation layer comprises thermoplastic polyimide. In the same manner, a heat resistant/radiation resistant power cable has an insulation layer comprising thermoplastic polyimide on a conductor, and is provided with a protection cover comprising braid of alamide fibers at the outer circumference of the insulation layer. An incore structure test device for an FBR type reactor comprises the heat resistant/radiation resistant coaxial cable and/or the power cable. The thermoplastic polyimide can be extrusion molded, and has excellent radiation resistant by the extrusion, as well as has high dielectric withstand voltage, good flexibility and electric characteristics at high temperature. The incore structure test device for the FBR type reactor of the present invention comprising such a cable has excellent reliability and durability. (T.M.)

1993-11-04

248

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

249

Crystal structures and magnetic properties of the BaAl4-type structure derivatives in Gd–Al–Ga system  

International Nuclear Information System (INIS)

Highlights: •We study the crystal structure of GdAlxGa4?x compounds with 8–66 at.% Ga. •Existing range of these compounds is fragmented into seven individual regions. •The effective magnetic moments have been calculated. •The excess magnetic moments are caused by the contribution of the non-4f electrons. -- Abstract: The crystal structures of GdAlxGa4?x?v compounds (8–66 at.% Ga, x = 3.6–0.70, v = 0–0.12) were studied by the X-ray diffraction methods (both single crystal and powder diffraction ones). Two new types of structure (monoclinic GdAl3.00Ga0.76 and orthorhombic GdAl2Ga2) were shown to be constructed of two distorted BaAl4-like fragments. Reasoning from the peculiarities of crystal structures, the whole existence region of the GdAlxGa4?x?v compounds is fragmented into seven narrow individual ones (seven compounds). At the temperature range 300–650 K the GdAlxGa4?x?v alloys were shown to be paramagnets with magnetic moments decreasing from 8.07 to 7.84?B with Ga-content increasing

2013-11-05

250

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

251

New phosphides of the Nb_4CoSi type structure  

International Nuclear Information System (INIS)

For the first time stated is the formation of Hf_4FeP, Hf_4CoP and TaFeP phosphides having the Nb_4CoSi type structure. Binary intermetallic compounds TaCo, Ta_2Ni, Zr_2Co, Zr_2Ni, Hf_2Ni are shown to disslove up to 17 at.% P. Maximum composition of these solid solutions is characterized by ordered distribution of Co(or Ni)and P atoms

1980-01-01

252

Population Structure and Properties of Candida albicans, as Determined by Multilocus Sequence Typing  

Digital Repository Infrastructure Vision for European Research (DRIVER)

We submitted a panel of 416 isolates of Candida albicans from separate sources to multilocus sequence typing (MLST). The data generated determined a population structure in which four major clades of closely related isolates were delineated, together with eight minor clades comprising five or more isolates. By Fisher's exact test, a statistically significant association was found between particular clades and the anatomical source, geographical source, ABC genotype, decade of isolation, and h...

2005-01-01

253

THE DEVELOPMENT AND STANDARDIZATION OF A STRUCTURED OBSERVATION ASSESSMENT OF TYPE A BEHAVIOR FOR CHILDREN  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of this research project was to develop an instrument to measure Type A behavior, or coronary-prone behavior, in children. A Structured Observation Assessment (SOA) was composed of items selected to represent three factors of coronary-prone behavior: competitiveness, achievement-striving; impatience; and speech stylistics. 128 children were tested, an equal number of male and female eight- and ten-year-olds. Race and residence (urban vs. rural) were represented in the same proport...

1984-01-01

254

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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 ...

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

2012-01-01

255

Structural myocardial involvement in adult patients with type 1 myotonic dystrophy  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Myotonic dystrophy type 1 (DM1) is the commonest muscular dystrophy in adults, affecting multiple organs in addition to skeletal muscles. Cardiac conduction system abnormalities are well recognized as an important component of DM1 phenotype; however, primary structural myocardial abnormalities, which may predispose these patients to congestive heart failure, are not as well characterized. We reviewed the retrospective analysis of the clinical and echocardiographic findings in adult patients w...

2013-01-01

256

Structure of the heterotrimeric complex that regulates type III secretion needle formation  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type III secretion systems (T3SS), found in several Gram-negative pathogens, are nanomachines involved in the transport of virulence effectors directly into the cytoplasm of target cells. T3SS are essentially composed of basal membrane-embedded ring-like structures and a hollow needle formed by a single polymerized protein. Within the bacterial cytoplasm, the T3SS needle protein requires two distinct chaperones for stabilization before its secretion, without which the entire T3SS is nonfuncti...

Quinaud, Manuelle; Ple?, Sophie; Job, Viviana; Contreras-martel, Carlos; Simorre, Jean-pierre; Attree, Ina; Dessen, Andre?a

2007-01-01

257

Type VI collagen microfibrils: evidence for a structural association with hyaluronan  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type VI collagen, a widespread structural component of connective tissues, has been isolated in abundance from fetal bovine skin by a procedure involving bacterial collagenase digestion under nonreducing, nondenaturing conditions and gel filtration chromatography. Rotary shadowing electron microscopic analysis revealed that the collagen VI was predominantly in the form of extensive intact microfibrillar arrays. These microfibrils were seen in association with hyaluronan, which was identified ...

1992-01-01

258

Recent progress in W-structured type-II superlattice photodiodes  

Science.gov (United States)

Recently we have achieved significant improvements in the performance of LWIR type-II superlattice photodiodes, with discrete devices beginning to demonstrate dynamic impedance-area product (R0A) levels approaching the MCT trend line and quantum efficiency exceeding 30% in devices without anti-reflection coatings. We discuss the key innovations that have led to these improvements, including modified W-structures, band-gap grading, and hybrid superlattices.

Aifer, E. H.; Vurgaftman, I.; Canedy, C. L.; Warner, J. H.; Jackson, E. M.; Tischler, J. G.; Meyer, J. R.

2007-03-01

259

Recombining Population Structure of Plesiomonas shigelloides (Enterobacteriaceae) Revealed by Multilocus Sequence Typing? †  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Plesiomonas shigelloides is an emerging pathogen that is widespread in the aquatic environment and is responsible for intestinal diseases and extraintestinal infections in humans and other animals. Virtually nothing is known about its genetic diversity, population structure, and evolution, which severely limits epidemiological control. We addressed these questions by developing a multilocus sequence typing (MLST) system based on five genes (fusA, leuS, pyrG, recG, and rpoB) and analyzing 77 e...

Salerno, Anna; Dele?toile, Alexis; Lefevre, Martine; Ciznar, Ivan; Krovacek, Karel; Grimont, Patrick; Brisse, Sylvain

2007-01-01

260

Epitope mapping of monoclonal antibodies against human immunodeficiency virus type 1 structural proteins by using peptides.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Murine monoclonal antibodies directed against the structural proteins p17 and p24 of human immunodeficiency virus type 1 were investigated in an epitope mapping system. Overlapping peptides consisting of 15 amino acids of the p17 and p24 protein, respectively, were used as competitors in an enzyme-linked immunosorbent assay. Three different immunogenic regions (A, B, and C) could be defined, one on p17 and two on p24. Twenty monoclonal antibodies reacted with the human immunodeficiency virus ...

Niedrig, M.; Hinkula, J.; Weigelt, W.; L Age-stehr, J.; Pauli, G.; Rosen, J.; Wahren, B.

1989-01-01

 
 
 
 
261

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2012-01-01

262

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

263

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

Science.gov (United States)

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

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

2013-04-01

264

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

265

Structural insights into serine protease inhibition by a marine invertebrate BPTI Kunitz-type inhibitor.  

Science.gov (United States)

Proteins isolated from marine invertebrates are frequently characterized by exceptional structural and functional properties. ShPI-1, a BPTI Kunitz-type inhibitor from the Caribbean Sea anemone Stichodactyla helianthus, displays activity not only against serine-, but also against cysteine-, and aspartate proteases. As an initial step to evaluate the molecular basis of its activities, we describe the crystallographic structure of ShPI-1 in complex with the serine protease bovine pancreatic trypsin at 1.7Å resolution. The overall structure and the important enzyme-inhibitor interactions of this first invertebrate BPTI-like Kunitz-type inhibitor:trypsin complex remained largely conserved compared to mammalian BPTI-Kunitz inhibitor complexes. However, a prominent stabilizing role within the interface was attributed to arginine at position P3. Binding free-energy calculations indicated a 10-fold decrease for the inhibitor affinity against trypsin, if the P3 residue of ShPI-1 is mutated to alanine. Together with the increased role of Arg(11) at P3 position, slightly reduced interactions at the prime side (Pn') of the primary binding loop and at the secondary binding loop of ShPI-1 were detected. In addition, the structure provides important information for site directed mutagenesis to further optimize the activity of rShPI-1A for biotechnological applications. PMID:22975140

García-Fernández, Rossana; Pons, Tirso; Perbandt, Markus; Valiente, Pedro A; Talavera, Ariel; González-González, Yamile; Rehders, Dirk; Chávez, María A; Betzel, Christian; Redecke, Lars

2012-11-01

266

Structure of human POFUT2: insights into thrombospondin type 1 repeat fold and O-fucosylation.  

Science.gov (United States)

Protein O-fucosylation is a post-translational modification found on serine/threonine residues of thrombospondin type 1 repeats (TSR). The fucose transfer is catalysed by the protein O-fucosyltransferase 2 (POFUT2) and >40 human proteins contain the TSR consensus sequence for POFUT2-dependent fucosylation. To better understand O-fucosylation on TSR, we carried out a structural and functional analysis of human POFUT2 and its TSR substrate. Crystal structures of POFUT2 reveal a variation of the classical GT-B fold and identify sugar donor and TSR acceptor binding sites. Structural findings are correlated with steady-state kinetic measurements of wild-type and mutant POFUT2 and TSR and give insight into the catalytic mechanism and substrate specificity. By using an artificial mini-TSR substrate, we show that specificity is not primarily encoded in the TSR protein sequence but rather in the unusual 3D structure of a small part of the TSR. Our findings uncover that recognition of distinct conserved 3D fold motifs can be used as a mechanism to achieve substrate specificity by enzymes modifying completely folded proteins of very wide sequence diversity and biological function. PMID:22588082

Chen, Chun-I; Keusch, Jeremy J; Klein, Dominique; Hess, Daniel; Hofsteenge, Jan; Gut, Heinz

2012-07-18

267

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

International Nuclear Information System (INIS)

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

2010-12-01

268

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

Science.gov (United States)

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

Zhang, Jiapu; Liu, David D W

2011-06-01

269

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

270

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

International Nuclear Information System (INIS)

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

2011-10-01

271

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

Energy Technology Data Exchange (ETDEWEB)

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

Jaksic, Nikola, E-mail: nikola.jaksic@ipp.mpg.de [Max-Planck-Institute for Plasma Physics, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany); Mendelevitch, Boris; Tretter, Joerg [Max-Planck-Institute for Plasma Physics, EURATOM Association, Boltzmannstrasse 2, D-85748 Garching (Germany)

2011-10-15

272

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2006-08-29

273

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

CERN Multimedia

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

Gorban, A N; Zinovyev, A Yu

2011-01-01

274

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

275

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

Science.gov (United States)

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. PMID:8107091

Li, X; Bokman, A M; Llinás, M; Smith, R A; Dobson, C M

1994-02-01

276

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

Directory of Open Access Journals (Sweden)

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

SerbanCMusca

2011-04-01

277

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

International Nuclear Information System (INIS)

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

2009-01-01

278

Corrosion preventing method for BWR type reactor and structural material thereof  

International Nuclear Information System (INIS)

In a method of preventing corrosion, for moderating a corrosion circumstance of reactor structural components by injection of hydrogen while suppressing transfer of 16N into a turbine system, an electrode is disposed in reactor water, a potential difference between the electrode and the reactor core structural materials is controlled as required, and the potential of the reactor core structural materials is reduced to -230mV or lower based on a standard hydrogen electrode potential reference. A value of a current flowing between the reactor structural materials and the metal electrode can be controlled by applying voltage, so that the dose rate of a turbine building can be controlled. The corrosion circumstance of the reactor structural materials can be moderated, which would be difficult by hydrogen injection, by using a Galvani method and a combination of the Galvani method and a compulsory charging method. Accordingly, corrosion of the reactor core in a BWR type reactor which is exposed to the severest corrosion circumstance can be reduced while suppressing the amount of radioactivity in pipelines of a main steam system and a turbine system and also suppressing dose rate at the boundary of the site, thereby enabling to remarkably improve reactor integrity and safety. (N.H.)

1993-04-06

279

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

CERN Document Server

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

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

2012-01-01

280

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

Science.gov (United States)

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

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

2014-03-01

 
 
 
 
281

Insect-inspired wing actuation structures based on ring-type resonators  

Science.gov (United States)

In this paper, we illustrate and study the opportunities of resonant ring type structures as wing actuation mechanisms for a flapping wing Micro Air Vehicle (MAV). Various design alternatives are presented and studied based on computational and physical models. Insects provide an excellent source of inspiration for the development of the wing actuation mechanisms for flapping wing MAVs. The insect thorax is a structure which in essence provides a mechanism to couple the wing muscles to the wings while offering weight reduction through application of resonance, using tailored elasticity. The resonant properties of the thorax are a very effective way to reducing the power expenditure of wing movement. The wing movement itself is fairly complex and is guided by a set of control muscles and thoracic structures which are present in proximity of the wing root. The development of flapping wing MAVs requires a move away from classical structures and actuators. The use of gears and rotational electric motors is hard to justify at the small scale. Resonant structures provide a large design freedom whilst also providing various options for actuation. The move away from deterministic mechanisms offers possibilities for mass reduction.

Bolsman, Caspar T.; Goosen, Johannes F. L.; van Keulen, Fred

2008-05-01

282

Crystal Structures of Ln4Ni3O8 (Ln = La, Nd) T?-type Nickelates  

Energy Technology Data Exchange (ETDEWEB)

Single-phase Ln4Ni3O8 (Ln = La, Nd) nickelates were synthesized and their crystal structures were determined by Rietveld refinement of powder neutron diffraction data. The crystal structures of these mixed-valent Ni1+/Ni2+ phases belong to the T'-type and are built by intergrowth of LnO2 fluorite layers with triple NiO2 infinite-layer structural blocks. The major driving force of transformation of the LnO rock-salt block of the parent Ln4Ni3O10-d Ruddlesden-Popper phases to the fluorite arrangement in the reduced Ln4Ni3O8 phases is attributed to internal structural stress. This transformation allows longer Ni-O bonds in Ln4Ni3O8 without overstretching of the Ln-O bonds, especially in the equatorial plane. The observed displacement of Ni atoms from the outer NiO2 planes toward the Ni atom of the central NiO2 plane in Ln4Ni3O8 is ascribed to large electrostatic repulsion from the fluorite part of the structure. X-ray absorption spectra near the K-edge of Ni suggest that the charge density on the nickel ion is similar for all members of the T'-type Lnn+1NinO2n+2 homologous series, which correlates with nearly constant Ni-O bond lengths observed in all the reduced nickelates. This suggests that the formal changes in the valence state of Ni affect the covalency of the Ni-O bond.

Poltavets,K.; Lokshin, A.; Croft, M.; Mandal, T.; Egami, T.; Greenblatt, M.

2007-01-01

283

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

284

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

CERN Multimedia

The fine spectral structures of solar radio type-I bursts were observed by the solar radio telescope AMATERAS. The spectral characteristics, such as the peak flux, duration, and bandwidth, of the individual burst elements were satisfactorily detected by the highly resolved spectral data of AMATEAS with the burst detection algorithm that is improved in this study. The peak flux of the type-I bursts followed a power-law distribution with a spectral index of 2.9-3.3, whereas their duration and bandwidth were distributed more exponentially. There were almost no correlations between the peak flux, duration, and bandwidth. That means there were no similarity shapes in the burst spectral structures. We defined the growth rate of a burst as the ratio between its peak flux and duration. There was a strong correlation between the growth rate and peak flux. These results suggest that the free energy of type-I bursts that is originally generated by non-thermal electrons is modulated in the subsequent stages of the genera...

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

2014-01-01

285

Predicting ?-turns and their types using predicted backbone dihedral angles and secondary structures  

Directory of Open Access Journals (Sweden)

Full Text Available Abstract Background ?-turns are secondary structure elements usually classified as coil. Their prediction is important, because of their role in protein folding and their frequent occurrence in protein chains. Results We have developed a novel method that predicts ?-turns and their types using information from multiple sequence alignments, predicted secondary structures and, for the first time, predicted dihedral angles. Our method uses support vector machines, a supervised classification technique, and is trained and tested on three established datasets of 426, 547 and 823 protein chains. We achieve a Matthews correlation coefficient of up to 0.49, when predicting the location of ?-turns, the highest reported value to date. Moreover, the additional dihedral information improves the prediction of ?-turn types I, II, IV, VIII and "non-specific", achieving correlation coefficients up to 0.39, 0.33, 0.27, 0.14 and 0.38, respectively. Our results are more accurate than other methods. Conclusions We have created an accurate predictor of ?-turns and their types. Our method, called DEBT, is available online at http://comp.chem.nottingham.ac.uk/debt/.

Hirst Jonathan D

2010-07-01

286

Preparation and crystal structure of quaternary silicide carbides with Dy2Fe2Si2C type structure  

International Nuclear Information System (INIS)

The compounds A2Fe2Si2C (A=La,Ce,Sm,Th) and A2Re2Si2C (A=Y,La-Nd,Sm,Gd-Er,Th) have been prepared for the first time. They crystallize with the Dy2Fe2Si2C type structure, which was refined for Th2Re2Si2C from single-crystal X-ray data: C2/m, a=1117.82(9) pm, b=417.53(4) pm, c=702.93(7) pm, ?=128.721(7) , Z=2, R=0.023 for 648 structure factors and 22 variable parameters. Some rhenium is present on the silicon site of this compound, resulting in the exact composition Th2Re2.086(4)Si1.914(4)C. The interatomic distances of this structure are compared with those of the previously reported isotypic and isoelectronic compounds Dy2Fe2Si2C and Tm2Fe2Si2C. The Re-Re bonds within the two-dimensionally infinite rhenium-silicon-carbon polyanion are stronger than the Fe-Fe bonds of the iron compound, while all other bonds in the rhenium-silicon-carbon polyanion (Re-Si, Re-C, Si-Si) are weaker than the corresponding bonds of the iron compound. Thus, the electron count of the transition metal atoms may be close to 18 in both structures, in spite of the differing formal charges of the polyanion: (Fe2Si2C)-6 vs. (Re2Si2C)-8. (orig.)

1998-02-20

287

Reconstruction of alveolus-like structure from alveolar type II epithelial cells in three-dimensional collagen gel matrix culture.  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The purpose of this study is to reconstruct an alveolus-like structure from alveolar type II epithelial cells in a culture condition. Isolated alveolar type II epithelial cells of the rat were cultured in a three-dimensional collagen gel matrix. Single type II cells formed cellular aggregates that had a lumen after cell division in this culture condition. Through proliferation of the component cells, these aggregates grew to assume a globular or branching structure, part of which in turn deve...

1993-01-01

288

Prediction algorithm for amino acid types with their secondary structure in proteins (PLATON) using chemical shifts  

Energy Technology Data Exchange (ETDEWEB)

The algorithm PLATON is able to assign sets of chemical shifts derived from a single residue to amino acid types with its secondary structure (amino acid species). A subsequent ranking procedure using optionally two different penalty functions yields predictions for possible amino acid species for the given set of chemical shifts. This was demonstrated in the case of the {alpha}-spectrin SH3 domain and applied to 9 further protein data sets taken from the BioMagRes database. A database consisting of reference chemical shift patterns (reference CSPs) was generated from assigned chemical shifts of proteins with known 3D-structure. This reference CSP database is used in our approach for extracting distributions of amino acid types with their most likely secondary structure elements (namely {alpha}-helix, {beta}-sheet, and coil) for single amino acids by comparison with query CSPs. Results obtained for the 10 investigated proteins indicates that the percentage of correct amino acid species in the first three positions in the ranking list, ranges from 71.4% to 93.2% for the more favorable penalty function. Where only the top result of the ranking list for these 10 proteins is considered, 36.5% to 83.1% of the amino acid species are correctly predicted. The main advantage of our approach, over other methods that rely on average chemical shift values is the ability to increase database content by incorporating newly derived CSPs, and therefore to improve PLATON's performance over time.

Labudde, D.; Leitner, D.; Krueger, M.; Oschkinat, H. [Forschungsinstitut fuer Molekulare Pharmakologie (Germany)], E-mail: oschkinat@fmp-berlin.de

2003-01-15

289

Prediction algorithm for amino acid types with their secondary structure in proteins (PLATON) using chemical shifts  

International Nuclear Information System (INIS)

The algorithm PLATON is able to assign sets of chemical shifts derived from a single residue to amino acid types with its secondary structure (amino acid species). A subsequent ranking procedure using optionally two different penalty functions yields predictions for possible amino acid species for the given set of chemical shifts. This was demonstrated in the case of the ?-spectrin SH3 domain and applied to 9 further protein data sets taken from the BioMagRes database. A database consisting of reference chemical shift patterns (reference CSPs) was generated from assigned chemical shifts of proteins with known 3D-structure. This reference CSP database is used in our approach for extracting distributions of amino acid types with their most likely secondary structure elements (namely ?-helix, ?-sheet, and coil) for single amino acids by comparison with query CSPs. Results obtained for the 10 investigated proteins indicates that the percentage of correct amino acid species in the first three positions in the ranking list, ranges from 71.4% to 93.2% for the more favorable penalty function. Where only the top result of the ranking list for these 10 proteins is considered, 36.5% to 83.1% of the amino acid species are correctly predicted. The main advantage of our approach, over other methods that rely on average chemical shift values is the ability to increase database content by incorporating newly derived CSPs, and therefore to improve PLATON's performance over time

2003-01-01

290

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

DEFF Research Database (Denmark)

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

Engsig-Karup, Allan Peter; Hesthaven, Jan

2008-01-01

291

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

International Nuclear Information System (INIS)

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

2007-09-07

292

Reference flaw size for structural and fracture analysis of Types 1 and 2 waste tanks  

Energy Technology Data Exchange (ETDEWEB)

High Level Waste Engineering (HLWE) is reviewing the Technical Standard requirements for tank level and minimum wall temperature. These requirements are necessary to minimize the probability of brittle fracture of the primary liner due to normal operating and/or seismic loads. The review includes the determination of a reference flaw size, a maximum through-wall crack length, which may reasonably be applied to structural and fracture analysis of the Type I and II waste tank primary liners. This memorandum briefly discusses the mechanism of crack initiation and propagation, the inspections of primary wall cracks, and a statistical analysis of the measured crack lengths. Recommendations on additional analyses which may increase the confidence in the reference flaw size will also be presented. The primary liner for Type I and II waste tanks is fabricated from ASTM A285, Grade B carbon steel (A285). The liner received no heat treatments to relieve residual stresses in the heat affected zones. Five Type I waste tanks and all four Type II waste tanks developed through-wall cracks. Leaks developed in tanks 9, 10,14 and 16 within less than two years. Small surface cracks were also observed on the interior of the tank primary. The cracks were perpendicular to the butt welds and extended through the heat affected zone before stopping shortly after penetrating the base metal. The largest leakage of radioactive waste, approximately 185,000 gallons from the primary into the annulus, occurred from Tank 16, a Type II waste tank. During inspections of this tank over 300 leaks were discovered with the longest observed crack being approximately 6 inches. Due to the large number of observed cracks and the amount of leakage, this wag the only tank that was surveyed for crack lengths. For this analysis, Tank 16 will be considered representative of all Type I and II waste tanks because the materials, construction practices, and tank chemistry represented a worst case.

Wiersma, B.J.; Sindelar, R.L.

1994-01-01

293

Dynamical structure of solar radio burst type III as evidence of energy of solar flares  

Science.gov (United States)

Observations of low frequency solar type III radio bursts associated with the ejection of plasma oscillations localized disturbance is due to excitation atoms in the plasma frequency incoherent radiations play a dominant role at the meter and decimeter wavelengths. Here, we report the results of the dynamical structure of solar flare type III that occurred on 9th March 2012 at National Space Centre, Sg Lang, Selangor, Malaysia by using the CALLISTO system. These bursts are associated with solar flare type M6 which suddenly ejected in the active region AR 1429 starting at 03:32 UT and ending at 05:00 UT with the peak at 04:12 UT. The observation showed an initial strong burst occurred due to strong signal at the beginning of the phase. We also found that both solar burst and flares tend to be a numerous on the same day and probability of chance coincidence is high. It is clearly seen that an impulsive lace burst was detected at 4:24 UT and it is more plausible that the energies are confined to the top of the loop when we compared with X-ray results. Associated with this event was type II with velocities 1285 km/s and type IV radio sweeps along with a full halo Coronal Mass Ejections (CMEs) first seen in SOHO/LASCO C2 imagery at 09/0426 Z. We concluded that the significance of study solar burst type III lies in the fact that the emission at decimetric wavelength comes from the role of magnetic field in active region that may provide the key to the energy release mechanism in a flare.

Hamidi, Zety Sharizat Binti

2013-11-01

294

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

Directory of Open Access Journals (Sweden)

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

Elahi-Moghaddam Zohreh

2013-01-01

295

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

Science.gov (United States)

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

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

2013-10-01

296

On the nature of IC 3328, an early-type dwarf galaxy with weak spiral structure  

CERN Document Server

Various early-type dwarf galaxies with disk features were identified in the Virgo cluster, including objects that display weak grand-design spiral arms despite being devoid of gas. Are these still related to the classical dEs, or are they a continuation of ordinary spiral galaxies? Kinematical information of acceptable quality is available for one of these galaxies, IC 3328. We perform an investigation of its dynamical configuration, taking into account the effect of asymmetric drift, and using the Toomre parameter as well as density wave considerations. The derived mass-to-light ratios and rotational velocities indicate the presence of a significant dynamically hot component in addition to the disk. However, unambiguous conclusions need to await the availability of further data for this and other early-type dwarfs with spiral structure.

Lisker, Thorsten

2009-01-01

297

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

International Nuclear Information System (INIS)

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

1985-01-01

298

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

Directory of Open Access Journals (Sweden)

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

ArthurRagauskas

2014-01-01

299

High-pressure U3O8 with the fluorite-type structure  

Science.gov (United States)

A new high-pressure phase of U3O8, which has a fluorite-type structure, forms at pressures greater than ~8.1 GPa that was confirmed by in situ x-ray diffraction (XRD) measurements. The fluorite-type U3O8 is stable at pressures at least up to ~40 GPa and temperatures to 1700 K, and quenchable to ambient conditions. Based on the XRD analysis, there is a huge volume collapse (>20%) for U3O8 during the phase transition and the quenched high-pressure phase is 28% denser than the initial orthorhombic phase at ambient conditions. The high-pressure phase has a very low compressibility comparing with the starting orthorhombic phase.

Zhang, F. X.; Lang, M.; Wang, J. W.; Li, W. X.; Sun, K.; Prakapenka, V.; Ewing, R. C.

2014-05-01

300

Kinetics of formation of twinned structures under L1_0 type orderings in alloys  

CERN Document Server

The earlier-developed master equation approach and kinetic cluster methods are applied to study kinetics of L1_0 type orderings in alloys, including the formation of twinned structures characteristic of cubic-tetragonal-type phase transitions. A microscopical model of interatomic deformational interactions is suggested which generalizes a similar model of Khachaturyan for dilute alloys to the physically interesting case of concentrated alloys. The model is used to simulate A1->L1_0 transformations after a quench of an alloy from the disordered A1 phase to the single-phase L1_0 state for a number of alloy models with different chemical interactions, temperatures, concentrations, and tetragonal distortions. We find a number of peculiar features in both transient microstructures and transformation kinetics, many of them agreeng well with experimental data. The simulations also demonstrate a phenomenon of an interaction-dependent alignment of antiphase boundaries in nearly-equilibrium twinned bands which seems to...

Belashchenko, K D; Samolyuk, G D; Vaks, V G

2001-01-01

 
 
 
 
301

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

Science.gov (United States)

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

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

2014-05-12

302

Repeatable, multiple-peaked structure in Type I X-ray bursts  

International Nuclear Information System (INIS)

A distinct, identifiable, multiple-peaked structure has been observed in Type I X-ray bursts from three sources. At energies below 6 keV, the light curves look like typical Type I burst. At higher energies, the burst is double-peaked, with both the depth of the dip and the separation between the peaks increasing with energy. A light curve of the energy-integrated intensity shows no distinct double peak, suggesting that only a single energy release occurs. Blackbody fits to the evolving burst spectra yield changing radii and temperatures, inversely correlated, during the early part of the burst. The physical interpretation of these changes is uncertain. Burst decay spectra yield relatively constant radii with decreasing temperatures. We propose that Compton scattering may be responsible for the dips in the higher-energy light curves by shifting photons to lower energies

1980-08-15

303

The structural transition from NaCl to CsCl type in cesium hydride  

International Nuclear Information System (INIS)

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

1982-12-01

304

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

International Nuclear Information System (INIS)

One lamellar phase, observed in the mitochondrial lipids-water system at low temperature (ca 253 K) and at low water content (ca 15%), contains four lipid monolayers in its unit cell, two of type ? and two of type ?. Previous X-ray scattering studies of this phase led to an ambiguity: the phase could contain either two homogeneous bilayers, one ? and one ?, or two mixed bilayers, each formed by an ? and a ? monolayer. A solution to this problem was sought in a neutron scattering study as a function of the D_2O/H_2O ratio. Because of limited resolution, straightforward analysis of the neutron scattering data leads also to ambiguous results. Using a more sophisticated analysis based upon the zeroth- and second-order moments of the Patterson peaks relevant to the exchangeable components, it is shown that the weight of the evidence is in favour of a structure containing mixed bilayers. (Auth.)

1980-12-01

305

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

International Nuclear Information System (INIS)

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

2014-03-15

306

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2014-03-15

307

Amorphous analogue of metastable modification of InSb with NaCl type structure produced under ion bombardment  

International Nuclear Information System (INIS)

Polycrystalline InSb films with sphalerite-like structure (B3) were irradiated by 150 keV Ne ions. The results obtained point to the formation of amorphous analogue of the NaCl (B1) type structure in the films. This structural transition takes place under the effect of radiation damages accumulating in the amorphous phase and enhancing its free energy

1985-01-01

308

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2011-10-17

309

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

International Nuclear Information System (INIS)

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

1986-10-01

310

Positive convolution structure for a class of Heckman-Opdam hypergeometric functions of type BC  

CERN Document Server

In this paper, we derive explicit product formulas and positive convolution structures for three continuous classes of Heckman-Opdam hypergeometric functions of type $BC$. For specific discrete series of multiplicities these hypergeometric functions occur as the spherical functions of non-compact Grassmann manifolds $G/K$ over one of the (skew) fields $\\mathbb F= \\mathbb R, \\mathbb C, \\mathbb H.$ We write the product formula of these spherical functions in an explicit form which allows analytic continuation with respect to the parameters. In each of the three cases, we obtain a series of hypergroup algebras which include the commutative convolution algebras of $K$-biinvariant functions on $G$.

Rösler, Margit

2009-01-01

311

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

International Nuclear Information System (INIS)

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

2007-12-27

312

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

Directory of Open Access Journals (Sweden)

Full Text Available Samples of natural HEU-type zeolites ? clinoptilolite-Ca, from the Novakovici deposit (near Prijedor, Bosnia and Herzegovina were treated with the hydrochloric acid of various concentrations (from 10-3 M to 2 M. Zeolitic tuffs before and after the acid treatment were examined using IR, XRPD, and chemical analyses. The changes in the crystal structure of acid treated samples showed a significant reduction in the crystallinity of zeolitic tuffs (60?70 %, which were effected by hydrochloric acid with concentrations of 1 M and above.

MAGDALENA TOMASEVIC-CANOVIC

2004-04-01

313

Enantiomer discrimination illustrated by high resolution crystal structures of type 4 phosphodiesterase  

Digital Repository Infrastructure Vision for European Research (DRIVER)

Type 4 phosphodiesterase (PDE4) inhibitors are emerging new treatment for a number of disorders including asthma and chronic obstructive pulmonary disease. Here we report the biochemical characterization on the second generation inhibitor (+)-1 (L-869298, IC50 = 0.4 nM) and its enantiomer (?)-1 (L-869299, IC50 = 43 nM), and their co-crystal structures with PDE4D at 2.0 Å resolution. In spite of the 107-fold affinity difference, both enantiomers interact with the same sets of residues in th...

Huai, Qing; Sun, Yingjie; Wang, Huanchen; Macdonald, Dwight; Aspiotis, Rene?e; Robinson, Howard; Huang, Zheng; Ke, Hengming

2006-01-01

314

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

1987-01-01

315

Structural basis of human ?-cell killing by CD8+ T cells in Type 1 diabetes  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The structural characteristics of autoreactive-T cell receptor (TCR) engagement of major histocompatability (MHC) class II-restricted self-antigens is established, but how autoimmune-TCRs interact with self-MHC class I has been unclear. We examined how CD8+ T cells kill human islet ?-cells, in Type-1 diabetes, via autoreactive-TCR (1E6) recognition of an HLA-A*0201-restricted glucose-sensitive preproinsulin peptide. Rigid ‘lock-and-key’ binding underpinned the 1E6-HLA-A*0201-peptide inte...

Bulek, Anna M.; Cole, David K.; Skowera, Ania; Dolton, Garry; Gras, Stephanie; Madura, Florian; Fuller, Anna; Miles, John J.; Gostick, Emma; Price, David A.; Drijfhout, Jan W.; Knight, Robin R.; Huang, Guo C.; Lissin, Nikolai; Molloy, Peter E.

2012-01-01

316

Structural independence of conjugative coupling protein TrwB from its Type IV secretion machinery  

Digital Repository Infrastructure Vision for European Research (DRIVER)

The stability of components of multiprotein complexes often relies on the presence of the functional complex. To assess structural dependence among the components of the R388 Type IV secretion system (T4SS), the steady-state level of several Trw proteins was determined in the absence of other Trw components. While several Trw proteins were affected by the lack of others, we found that the coupling protein TrwB is not affected by the absence of other T4SS components, nor did its absence alter ...

Larrea, Delfina; Paz, He?ctor D.; Arechaga, Ignacio; Cruz, Fernando La; Llosa, Matxalen

2013-01-01

317

Large-displacement analysis of beam-type structures considering elastic-plastic material behavior  

Energy Technology Data Exchange (ETDEWEB)

A one-dimensional finite element analysis is presented for large elastic-plastic displacements in beam-type structures. Spatial displacements and rotations are allowed to be large while strains are assumed to be small. The corresponding equilibrium equations are formulated in the framework of co-rotational description, using the virtual work principle. Material is assumed to be homogeneous and isotropic. Elastic-plastic material behavior is modeled supposing isotropic hardening law, while stress-strain curve is approximated as bilinear. An own computer program (BMCA) is developed, and its implementation is tested on several typical examples.

Lanc, D. [Department of Engineering Mechanics, Faculty of Engineering, University of Rijeka, Vukovarska 58, HR-51000 Rijeka (Croatia)], E-mail: dlanc@riteh.hr; Turkalj, G.; Brnic, J. [Department of Engineering Mechanics, Faculty of Engineering, University of Rijeka, Vukovarska 58, HR-51000 Rijeka (Croatia)

2009-01-15

318

Large-displacement analysis of beam-type structures considering elastic-plastic material behavior  

International Nuclear Information System (INIS)

A one-dimensional finite element analysis is presented for large elastic-plastic displacements in beam-type structures. Spatial displacements and rotations are allowed to be large while strains are assumed to be small. The corresponding equilibrium equations are formulated in the framework of co-rotational description, using the virtual work principle. Material is assumed to be homogeneous and isotropic. Elastic-plastic material behavior is modeled supposing isotropic hardening law, while stress-strain curve is approximated as bilinear. An own computer program (BMCA) is developed, and its implementation is tested on several typical examples

2009-01-15

319

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

Science.gov (United States)

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

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

2012-03-01

320

Hexagonal type Ising nanowire with core/shell structure: The phase diagrams and compensation behaviors  

Science.gov (United States)

The phase diagrams and compensation behaviors of a mixed spin (1/2-1) hexagonal Ising nanowire with core-shell structure are studied by using the effective-field theory with correlations. The effects of the interaction parameters and crystal field on the critical behaviors of the system are investigated, in detail. It has been found that the system shows first-order and second order phase transition, and tricritical point. Moreover, Q-, R-, S- and N-types of compensation behaviors in the Neél classification nomenclature as well as reentrant behaviors are observed in the system.

Kantar, Ersin; Kocakaplan, Yusuf

2014-01-01

 
 
 
 
321

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

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

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

2009-01-01

322

Hamiltonian Structures and Integrability for a Discrete Coupled KdV-Type Equation Hierarchy  

International Nuclear Information System (INIS)

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

2011-05-01

323

Profile structure of magnetic flux lines in type-II superconductor from a rectangular electron hologram  

DEFF Research Database (Denmark)

Profile magnetic configuration of a quantized flux line and flux-line lattice penetrating a type-II superconductor thing foil, niobium, was observed by electron holography and Lorentz microscopy using a 300 kV field-emission electron microscope. Each single flux line was distributed periodically as lattice structure in the mixed state just below its critical temperature of 8.5 K, while at low temperature of 5 K the flux lines were weakly bound as bundles. In order to observe the flux-line distribution over a wide area, discrete Fourier transform reconstruction in the holography was extended for a rectangular area without loss of information and data precision.

Harada, Ken; Beleggia, Marco

2003-01-01

324

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

International Nuclear Information System (INIS)

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

2006-01-01

325

Muon diffusion in intermetallic compounds of the MoSi2-type structure  

International Nuclear Information System (INIS)

The localization and diffusion of positive muons are studied in three binary metallic systems, Zr2Cu, Hf2Cu and Ti2Cu, presenting the MoSi2-type structure. Zero-field ?SR measurements are interpreted as the muons being static in the Tb/Ob interstitial site at low temperatures and, as the temperature is increased, starting diffusing through the network of Tb sites around the Ob site, until they reach a state occupying simultaneously the four Tb sites. Long-range diffusion is observed above 300 K. Activation energies for the lower-temperature diffusion processes are obtained. The results are interpreted in terms of the lattice structure characteristics. (author)

2001-06-04

326

Electronic structure of ionic PbFCl-type compounds under pressure  

International Nuclear Information System (INIS)

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

2003-03-19

327

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

Energy Technology Data Exchange (ETDEWEB)

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

Benmachiche, I.

2006-07-15

328

On the Structural Types of Reduplicative in The Book of Songs  

Directory of Open Access Journals (Sweden)

Full Text Available

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

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

Binghua DONG

2011-12-01

329

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

Science.gov (United States)

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

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

2013-01-01

330

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

Science.gov (United States)

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

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

2011-01-01

331

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

International Nuclear Information System (INIS)

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

2012-09-01

332

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

Science.gov (United States)

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

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

2014-02-01

333

Structural Complexities Influencing Biostratigraphic Interpretations of the Permian Nansen Formation type-section, Ellesmere Island, Canada  

Science.gov (United States)

The Carboniferous to Permian aged Nansen Formation is a cyclic carbonate shelf deposit and potential hydrocarbon reservoir. This formation is the thickest, most widespread carbonate sequence in the Sverdrup Basin. Deformed during the Eurekan Orogeny, the Nansen Fm. is topographically prominent and responsible for the rugged topography on Axel Heiburg and Ellesmere Island. The type-section for the Nansen Fm. is located on the north side of Hare Fiord, along Girty Creek. At this location there is an estimated stratigraphic thickness of 2 km. Due to easier access most of the stratigraphic work has been completed on nearby glacially exposed sections that traverse parallel to Girty Creek along glacial margins. Extensive biostratigraphy was completed on a glacier section to the west, however, in a glacier section to the east of Girty Creek, structural complexities appear to be repeating sections of the formation. Here, the Nansen formation is bounded by two regional reverse faults. This has produced duplex structures, with clearly exposed stacked horses, footwall synclines, and truncations. By projecting the structures observed along the eastern glacier section to the western glacier section that was used for biostratigraphic studies, it is clear that these structures would affect biostratigraphic interpretations. It was previously noted by biostratigraphers that thrust faults appear to be repeating sections of the Nansen formation. However by correlating all observed faults with the biostratigraphy, we can determine the extent to which the faulting has affected the interpretations, and whether all faults or stratigraphic repetitions are accounted for.

Hill, M.; Guest, B.

2011-12-01

334

UCr4C4 with filled MoNi4 type structure  

International Nuclear Information System (INIS)

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

1987-01-01

335

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

International Nuclear Information System (INIS)

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

1993-08-15

336

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

Science.gov (United States)

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

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

1999-01-01

337

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

Digital Repository Infrastructure Vision for European Research (DRIVER)

Abstract Introduction Diabetes is one of the most common endocrine disorders characterized by hyperglycemia due to defects in insulin secretion, insulin function, or both. Causing dysfunction in the body general metabolism, diabetes-induced chronic hyperglycemia leads to alterations in those endocrine glands involved in regulating the body metabolism. In this line, the present study has been conducted to investigate the effects of type 1 and type 2 diabetes on the structural ...

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

2013-01-01

338

Oxide-ion conduction and dielectric relaxations for fluorite type structure  

Energy Technology Data Exchange (ETDEWEB)

The oxide-ion conduction and dielectric properties of 10 mol% CaO stabilized ZrO{sub 2} (10CSZ) and 25 mol% Y{sub 2}O{sub 3} stabilized Bi{sub 2}O{sub 3} (25YSB) which are oxide ion conductors having a fluorite-type structure were investigated. The numerical analyses for the frequency dependences of dielectric constants ({epsilon}{sub r}') and dielectric loss factors ({epsilon}{sub r}'') revealed that the dielectric properties were explained by Debye-type polarization due to dopant-vacancy associates and/or electrolyte-electrode interfacial polarization due to charging or loss current. No Debye-type polarization was observed in 25YSB because of no effective charge at the Y{sup 3+}-doped Bi{sup 3+} site. On the other hand, two Debye-type dipoles observed in 10CSZ were assigned to two kinds of associates, [Ca{sub Zr}''-V{sub o}{sup {center_dot}{center_dot}}]{center_dot}, which was due to dopant-vacancy associates with two different distances between (Ca{sub Zr}'') and (V{sub o}{sup {center_dot}{center_dot}}). The frequency dependence of dielectric loss tangent (tan{delta}) in 25YSB was ascribed to the interface loss due to the charged current, while that of tan{delta} in 8YSZ was ascribed to the Debye-type dipoles in addition to the interface loss.

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

2011-06-15

339

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2013-09-05

340

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

International Nuclear Information System (INIS)

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

2013-09-05

 
 
 
 
341

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

CERN Document Server

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

Gai, Moshe

2014-01-01

342

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

Science.gov (United States)

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

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

2014-05-01

343

Structure-and-mechanism-based design and discovery of type II Mycobacterium tuberculosis dehydroquinate dehydratase inhibitors.  

Science.gov (United States)

Mycobacterium tuberculosis is the causative agent of tuberculosis, a lethal infection disease that attacks the lungs. Now it becomes the major global health risk because of very long latent period, the persistent increase of new cases, and the emergence of multidrug-resistant and extensively drug-resistant strains. Therefore, there is an urgent need for the development of new, safe and more efficient tuberculosis drugs. The shikimate pathway has been considered as the attractive drug target due to its essentiality in algae, higher plants, bacteria, and fungi, but absence from mammals. In this review, we focus on the recent development of a wide variety of inhibitors of type II Mycobacterium tuberculosis dehydroquinate dehydratase, the third enzyme of this pathway. The structural and mechanistic features of the enzyme for the design and discovery of the inhibitors have been described. The key factors on the structure, binding, and affinity of the inhibitors have been also highlighted. This may direct the further development of type II Mycobacterium tuberculosis dehydroquinate dehydratase inhibitors as potent tuberculosis drugs. PMID:24236726

Yao, Yuan; Li, Ze-Sheng

2014-01-01

344

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

Directory of Open Access Journals (Sweden)

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

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

Castejón, L.

1997-12-01

345

Flux growth and structure of two compounds with the EuIn2P2 structure type, AIn2P2 (A = Ca and Sr), and a new structure type, BaIn2P2.  

Science.gov (United States)

Single crystals of the new Zintl phases AIn2P2 [A = Ca (calcium indium phosphide), Sr (strontium indium phosphide) and Ba (barium indium phosphide)] have been synthesized from a reactive indium flux. CaIn2P2 and SrIn2P2 are isostructural with EuIn2P2 and crystallize in the space group P63/mmc. The alkaline earth cations A are located at a site with 3m symmetry; In and P are located at sites with 3m symmetry. The structure type consists of layers of A2+ cations separated by [In2P2]2- anions that contain [In2P6] eclipsed ethane-like units that are further connected by shared P atoms. This yields a double layer of six-membered rings in which the In-In bonds are parallel to the c axis and to one another. BaIn2P2 crystallizes in a new structure type in the space group P2(1)/m with Z = 4, with all atoms residing on sites of mirror symmetry. The structure contains layers of Ba2+ cations separated by [In2P2]2- layers of staggered [In2P6] units that form a mixture of four-, five- and six-membered rings. As a consequence of this more complicated layered structure, both the steric and electronic requirements of the large Ba2+ cation are met. PMID:19805864

Rauscher, Japheth F; Condron, Cathie L; Beault, Tanya; Kauzlarich, Susan M; Jensen, Newell; Klavins, Peter; MaQuilon, Samuel; Fisk, Zachary; Olmstead, Marilyn M

2009-10-01

346

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2012-03-27

347

Myotonic dystrophy type 1 RNA crystal structures reveal heterogeneous 1 × 1 nucleotide UU internal loop conformations.  

Science.gov (United States)

RNA internal loops often display a variety of conformations in solution. Herein, we visualize conformational heterogeneity in the context of the 5'CUG/3'GUC repeat motif present in the RNA that causes myotonic dystrophy type 1 (DM1). Specifically, two crystal structures of a model DM1 triplet repeating construct, 5'r[UUGGGC(CUG)(3)GUCC](2), refined to 2.20 and 1.52 Å resolution are disclosed. Here, differences in the orientation of the 5' dangling UU end between the two structures induce changes in the backbone groove width, which reveals that noncanonical 1 × 1 nucleotide UU internal loops can display an ensemble of pairing conformations. In the 2.20 Å structure, CUGa, the 5' UU forms a one hydrogen-bonded pair with a 5' UU of a neighboring helix in the unit cell to form a pseudoinfinite helix. The central 1 × 1 nucleotide UU internal loop has no hydrogen bonds, while the terminal 1 × 1 nucleotide UU internal loops each form a one-hydrogen bond pair. In the 1.52 Å structure, CUGb, the 5' UU dangling end is tucked into the major groove of the duplex. While the canonically paired bases show no change in base pairing, in CUGb the terminal 1 × 1 nucleotide UU internal loops now form two hydrogen-bonded pairs. Thus, the shift in the major groove induced by the 5' UU dangling end alters noncanonical base patterns. Collectively, these structures indicate that 1 × 1 nucleotide UU internal loops in DM1 may sample multiple conformations in vivo. This observation has implications for the recognition of this RNA, and other repeating transcripts, by protein and small molecule ligands. PMID:21988728

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

2011-11-15

348

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

Science.gov (United States)

The type VI secretion system (T6SS) is a bacterial protein-export machine that is capable of delivering virulence effectors between Gram-negative bacteria. The T6SS of Pseudomonas aeruginosa transports two lytic enzymes, Tse1 and Tse3, to degrade cell-wall peptidoglycan in the periplasm of rival bacteria that are competing for niches via amidase and muramidase activities, respectively. Two cognate immunity proteins, Tsi1 and Tsi3, are produced by the bacterium to inactivate the two antibacterial effectors, thereby protecting its siblings from self-intoxication. Recently, Tse1-Tsi1 has been structurally characterized. Here, the structure of the Tse3-Tsi3 complex is reported at 1.9?Å resolution. The results reveal that Tse3 contains a C-terminal catalytic domain that adopts a soluble lytic transglycosylase (SLT) fold in which three calcium-binding sites were surprisingly observed close to the catalytic Glu residue. The electrostatic properties of the substrate-binding groove are also distinctive from those of known structures with a similar fold. All of these features imply that a unique catalytic mechanism is utilized by Tse3 in cleaving glycosidic bonds. Tsi3 comprises a single domain showing a ?-sandwich architecture that is reminiscent of the immunoglobulin fold. Three loops of Tsi3 insert deeply into the groove of Tse3 and completely occlude its active site, which forms the structural basis of Tse3 inactivation. This work is the first crystallographic report describing the three-dimensional structure of the Tse3-Tsi3 effector-immunity pair. PMID:24100309

Wang, Tianyu; Ding, Jinjing; Zhang, Ying; Wang, Da-Cheng; Liu, Wei

2013-10-01

349

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

DEFF Research Database (Denmark)

O-GalNAc-glycosylation is one of the main types of glycosylation in mammalian cells. No consensus recognition sequence for the O-glycosyltransferases is known, making prediction methods necessary to bridge the gap between the large number of known protein sequences and the small number of proteins experimentally investigated with regard to glycosylation status. From O-GLYCBASE a total of 86 mammalian proteins experimentally investigated for in vivo O-GalNAc sites were extracted. Mammalian protein homolog comparisons showed that a glycosylated serine or threonine is less likely to be precisely conserved than a nonglycosylated one. The Protein Data Bank was analyzed for structural information, and 12 glycosylated structures were obtained. All positive sites were found in coil or turn regions. A method for predicting the location for mucin-type glycosylation sites was trained using a neural network approach. The best overall network used as input amino acid composition, averaged surface accessibility predictionstogether with substitution matrix profile encoding of the sequence. To improve prediction on isolated (single) sites, networks were trained on isolated sites only. The final method combines predictions from the best overall network and the best isolated site network; this prediction method correctly predicted 76% of the glycosylated residues and 93% of the nonglycosylated residues. NetOGlyc 3.1 can predict sites for completely new proteins without losing its performance. The fact that the sites could be predicted from averaged properties together with the fact that glycosylation sites are not precisely conserved indicates that mucin-type glycosylation in most cases is a bulk property and not a very site-specific one. NetOGlyc 3.1 is made available at www.cbs.dtu.dk/services/netoglyc.

Julenius, Karin; Mølgaard, Anne

2004-01-01

350

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

DEFF Research Database (Denmark)

O-GalNAc-glycosylation is one of the main types of glycosylation in mammalian cells. No consensus recognition sequence for the O-glycosyltransferases is known, making prediction methods necessary to bridge the gap between the large number of known protein sequences and the small number of proteins experimentally investigated with regard to glycosylation status. From O-GLYCBASE a total of 86 mammalian proteins experimentally investigated for in vivo O-GalNAc sites were extracted. Mammalian protein homolog comparisons showed that a glycosylated serine or threonine is less likely to be precisely conserved than a nonglycosylated one. The Protein Data Bank was analyzed for structural information, and 12 glycosylated structures were obtained. All positive sites were found in coil or turn regions. A method for predicting the location for mucin-type glycosylation sites was trained using a neural network approach. The best overall network used as input amino acid composition, averaged surface accessibility predictionstogether with substitution matrix profile encoding of the sequence. To improve prediction on isolated (single) sites, networks were trained on isolated sites only. The final method combines predictions from the best overall network and the best isolated site network; this prediction method correctly predicted 76% of the glycosylated residues and 93% of the nonglycosylated residues. NetOGlyc 3.1 can predict sites for completely new proteins without losing its performance. The fact that the sites could be predicted from averaged properties together with the fact that glycosylation sites are not precisely conserved indicates that mucin-type glycosylation in most cases is a bulk property and not a very site-specific one. NetOGlyc 3.1 is made available at www.cbs.dtu.dk/services/netoglyc.

Julenius, Karin; Mølgaard, Anne

2005-01-01

351

Structure and electrical properties of p-type twin ZnTe nanowires  

International Nuclear Information System (INIS)

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

2011-02-01

352

Structure and electrical properties of p-type twin ZnTe nanowires  

Science.gov (United States)

Resonant tunneling is firstly found in twin p-type ZnTe nanowire field-effect transistors. The twin ZnTe nanowires are synthesized via the thermal evaporation process. X-ray diffraction and high-resolution transmission electron microscopy characterization indicate that the as-grown twin nanowire has a zinc-blende crystal structure with an integrated growth direction of [11-1]. The twin plane is (11-1) and the angle between the mirror symmetrical planes is 141°. The formation of twins is attributed to the surface tension from the eutectic liquid droplet. Field-effect transistors based on single ZnTe twin nanowire are constructed, the corresponding electrical measurements demonstrate that the twin nanowires have a p-type conductivity with a mobility ( ? h ) of 0.11 cm2 V-1 S-1, and a carrier concentration ( n h ) of 1.1×1017 cm-3. Significantly, the negative differential resistance with a peak-to-valley current ratio of about 1.3 is observed in p-type twin ZnTe nanowire field-effect transistors at room temperature. As the periodic barriers produced in the periodic twin interfaces can form multi-barrier and multi-well along one-dimensional direction. The multibarrier can be modulated under external electrical field. When the resonant condition is met, the space charge will be enhanced with the inherent feedback mechanism, and the resonant tunneling will occur.

Li, Shanying; Jiang, Yang; Wu, Di; Wang, Binbin; Zhang, Yugang; Li, Junwei; Liu, Xinmei; Zhong, Honghai; Chen, Lei; Jie, Jiansheng

2011-02-01

353

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

CERN Document Server

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

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

2003-01-01

354

Preparation, structure and electrical conductivity of pyrochlore-type samarium-lanthanum zirconate ceramics  

International Nuclear Information System (INIS)

Highlights: ? Dense Sm2-xLaxZr2O7 ceramics were prepared by pressureless-sintering at 1973 K. ? Sm2-xLaxZr2O7 ceramics have a single phase of pyrochlore-type structure. ? The electrical conductivity of Sm2-xLaxZr2O7 increases with increasing temperature. ? Sm2-xLaxZr2O7 ceramics are oxide-ion conductors in low oxygen partial pressure. ? The electrical conductivity of Sm2-xLaxZr2O7 decreases with increasing La content. -- Abstract: A series of zirconate compounds with the general formula Sm2-xLaxZr2O7 (0 ? x ? 1.0) were prepared by pressureless-sintering method at 1973 K for 10 h in air. The relative density, structure and electrical conductivity of Sm2-xLaxZr2O7 ceramics were investigated by the Archimedes method, X-ray diffraction and impedance spectroscopy measurements. Sm2-xLaxZr2O7 (0 ? x ? 1.0) ceramics exhibit a pyrochlore-type structure. The measured electrical conductivity of Sm2-xLaxZr2O7 ceramics obeys the Arrhenius relation and gradually increases with increasing temperature from 673 to 1173 K. Sm2-xLaxZr2O7 ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 x 10-4 to 1.0 atm at all test temperature levels. The electrical conductivity of Sm2-xLaxZr2O7 ceramics decreases with increasing lanthanum content at identical temperature levels.

2011-09-01

355

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

Science.gov (United States)

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

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

2013-04-01

356

FY1995 research of new functional photonic devices bard on Type 2 quantum well structures; 1995 nendo type 2 kozo base no shingenri hikari kino device no kenkyu  

Energy Technology Data Exchange (ETDEWEB)

Quantum well photonic devices, such as high spied optical modulators and/or optical logic devices are indispensable for future large capacity optical fiber information systems. All of these devices have been fabricated using type 1 quantum well structures. Type 2 quantum well structures, which have entirely different properties from those of type 1 quantum well structures, have a potential for new functional devices based on new operation principle. The purpose of the research is to realize new quantum well photonic devices using type 2 structures. (1) InAlAs/InP type 2 multiple quantum well (MQW) diodes were grown by molecular beam epitaxy (MBE). A remarkable bistability was observed in the current-light output (I - L) characteristic for the first time. It was found that the bistability of the I - L characteristic corresponds to the bistability of the current - voltage (I - V) characteristic. These results can be applied for new optical bistable devices. (2) The hetero-interface quality was characterized for InAlAs/Inp type 2 single hetero structures. It was found that the photoluminescence (PL) intensity of the sample grown on (111)B substrates was enhanced by more than one order comparing with that grown on (100) substrates, while the 2 dimensional carrier density is about one order smaller for the sample grown on (111)B substrates. These results suggest that high quality hetero-interface can be grown by using (111)B substrates. (3) Two-dimensional - one dimensional mode change in GaAs MBE was observed using in-situ scanning electron microscopy. From this result, the optimized growth condition of hetero-interface was revealed. (NEDO)

NONE

1996-05-01

357

Raman spectra of lanthanide sesquioxide single crystals with A-type structure  

International Nuclear Information System (INIS)

Phonon data are given for La2O3, Pr2O3, and Nd2O3 single crystals. The polarized Raman spectra of Nd2O3 are presented and analysed according to Pauling's structure: Dsub(3d)sup(3)(P3m1), Z=1. A factor group analysis leads to the symmetries 2Asub(1g) + 2Esub(g) for the q = 0 lattice vibrations which give a non zero contribution in the first order Raman scattering. The experimental data are in complete agreement with these previsions. The four Raman active vibrations are shown to be those of Ln2O(II)2 entities within cages of O(I) atoms, O(I) and O(II) lying in Dsub(3d) and Csub(3v) crystal sites, respectively. There are two stretching (Asub(1g) + Esub(g)) and two bending (Asub(1g) + Esub(g)) modes, the assignments of which are made. A tentative comparison with the oxysulphides Ln2O2S, which have also a P3m1 structure, is presented. A linear correlation is found between the Ln-O(II) stretching mode frequency of the three studied sesquioxides and the c/a ratio of their hexagonal A-type structure. (author)

1979-07-01

358

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

CERN Multimedia

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

Zhang, J

2009-01-01

359

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

International Nuclear Information System (INIS)

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

1991-06-01

360

Oxidative dehydrogenation of isobutyl alcohol over different structure type of zeolites  

International Nuclear Information System (INIS)

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

2008-02-01

 
 
 
 
361

The structural and molecular biology of type I galactosemia: Enzymology of galactose 1-phosphate uridylyltransferase.  

Science.gov (United States)

Reduced galactose 1-phosphate uridylyltransferase (GALT) activity is associated with the genetic disease type I galactosemia. This results in an increase in the cellular concentration of galactose 1-phosphate. The accumulation of this toxic metabolite, combined with aberrant glycoprotein and glycolipid biosynthesis, is likely to be the major factor in molecular pathology. The mechanism of GALT was established through classical enzymological methods to be a substituted enzyme in which the reaction with UDP-glucose results in the formation of a covalent, UMP-histidine adduct in the active site. The uridylated enzyme can then react with galactose 1-phosphate to form UDP-galactose. The structure of the enzyme from Escherichia coli reveals a homodimer containing one zinc (II) and one iron (II) ion per subunit. This enzymological and structural knowledge provides the basis for understanding the biochemistry of this critical step in the Leloir pathway. However, a high-resolution crystal structure of human GALT is required to assist greater understanding of the effects of disease-associated mutations. PMID:21793161

McCorvie, Thomas J; Timson, David J

2011-09-01

362

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

Science.gov (United States)

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

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

2012-10-24

363

Pulsed laser deposition of superionic ceramic thin films: deposition and applications in electrochemistry  

Science.gov (United States)

Pulsed laser deposition (PLD) has been used to prepare two types of superionic ceramic thin films: (i) NASICON (Na superionic conductor) for a Na ion selective membrane and (ii) the mixed electronic and oxygen conductors La 1- xSr xMnO 3± ? (LSM) for the cathode in solid oxide fuel cells. NASICON thin films have good ionic conductivity with resistivities between 3×10 3 and 5×10 4 ? cm at room temperature and they have low surface particle densities depending upon the deposition conditions. When NASICON is deposited on polymeric (Raipore) membranes frequently employed for Na selectivity, the composite membranes show a significant increase of current efficiency of 23% for the production of sodium hydroxide from sodium sulfate using electrolysis. For LSM, very smooth and dense thin films are produced by PLD with the perovskite structure after an anneal at 950°C.

Meunier, Michel; Izquierdo, Ricardo; Hasnaoui, Lahcen; Quenneville, Eric; Ivanov, Dentcho; Girard, François; Morin, François; Yelon, Arthur; Paleologou, Michael

1998-05-01

364

Pulsed laser deposition of superionic ceramic thin films. Deposition and applications in electrochemistry  

Energy Technology Data Exchange (ETDEWEB)

Pulsed laser deposition (PLD) has been used to prepare two types of superionic ceramic thin films: (1) NASICON (Na superionic conductor) for a Na ion selective membrane and (2) the mixed electronic and oxygen conductors La{sub 1-x}Sr{sub x}MnO{sub 3{+-}{delta}} (LSM) for the cathode in solid oxide fuel cells. NASICON thin films have good ionic conductivity with resistivities between 3x10{sup 3} and 5x10{sup 4} {Omega} cm at room temperature and they have low surface particle densities depending upon the deposition conditions. When NASICON is deposited on polymeric (Raipore) membranes frequently employed for Na selectivity, the composite membranes show a significant increase of current efficiency of 23% for the production of sodium hydroxide from sodium sulfate using electrolysis. For LSM, very smooth and dense thin films are produced by PLD with the perovskite structure after an anneal at 950C

Meunier, Michel; Izquierdo, Ricardo; Hasnaoui, Lahcen; Quenneville, Eric; Yelon, Arthur [Department of Engineering Physics and Groupe de Recherche en Physique et Technologie des Couches Minces GCM, Ecole Polytechnique de Montreal, Montreal, QU (Canada); Ivanov, Dentcho [Microelectronics Center, New Jersey Institute of Technology, Newark, NJ (United States); Girard, Francois; Paleologou, Michael [Pulp and Paper Research Institute of Canada PAPRICAN, Pointe-Claire, QU (Canada); Morin, Francois [Institut de Recherche d`Hydro-Quebec IREQ, Varennes, QU (Canada)

1998-05-01

365

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

Science.gov (United States)

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

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

2013-12-01

366

An Examination of the Influence of Organizational Structure Types and Management Levels on Knowledge Management Practices in Organizations  

Directory of Open Access Journals (Sweden)

Full Text Available The purpose of this study was to investigate the difference between organizational structure types, andmanagement levels, in terms of perceived levels of knowledge management practices within organizations. Datawere collected from a sample of 155 individuals employed in San Diego County by way of a web-based survey,and were analyzed using analysis of variance (ANOVA. The results of the study indicate that the knowledgemanagement practices of knowledge transfer, information filtering, and knowledge culture are influenced byorganizational structure type. According to the study, knowledge sharing training is not significantly influencedby organizational structure type. Furthermore, the results of the study indicate there is no significant influence ofmanagement level on the knowledge management practices of knowledge transfer, information filtering,knowledge-sharing training, and knowledge culture. In summary, the results of this study solidify the assertionthat organizational structure types do influence knowledge management practices.

Jen S. Steiger

2014-05-01

367

Crystal structures and biochemical studies of human lysophosphatidic acid phosphatase type 6.  

Science.gov (United States)

Lysophosphatidic acid (LPA) is an important bioactive phospholipid involved in cell signaling through Gprotein-coupled receptors pathways. It is also involved in balancing the lipid composition inside the cell, and modulates the function of lipid rafts as an intermediate in phospholipid metabolism. Because of its involvement in these important processes, LPA degradation needs to be regulated as precisely as its production. Lysophosphatidic acid phosphatase type 6 (ACP6) is an LPA-specific acid phosphatase that hydrolyzes LPA to monoacylglycerol (MAG) and phosphate. Here, we report three crystal structures of human ACP6 in complex with malonate, L-(+)-tartrate and tris, respectively. Our analyses revealed that ACP6 possesses a highly conserved Rossmann-foldlike body domain as well as a less conserved cap domain. The vast hydrophobic substrate-binding pocket, which is located between those two domains, is suitable for accommodating LPA, and its shape is different from that of other histidine acid phosphatases, a fact that is consistent with the observed difference in substrate preferences. Our analysis of the binding of three molecules in the active site reveals the involvement of six conserved and crucial residues in binding of the LPA phosphate group and its catalysis. The structure also indicates a water-supplying channel for substrate hydrolysis. Our structural data are consistent with the fact that the enzyme is active as a monomer. In combination with additional mutagenesis and enzyme activity studies, our structural data provide important insights into substrate recognition and the mechanism for catalytic activity of ACP6. PMID:23807634

Li, Jun; Dong, Yu; Lü, Xingru; Wang, Lu; Peng, Wei; Zhang, Xuejun C; Rao, Zihe

2013-07-01

368

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

Science.gov (United States)

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

Lian, Jie

369

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

Energy Technology Data Exchange (ETDEWEB)

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

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

2010-10-05

370

Structural and electrical properties of p-type ZnO films prepared by Ultrasonic Spray Pyrolysis  

International Nuclear Information System (INIS)

Effects of atomic ratio of Zn:N:Al and solution concentration on the structural and electrical characteristic of ZnO films deposited by Ultrasonic Spray Pyrolysis using N-Al co-doping technique were investigated. Hall measurement indicated that with increasing Al doping, conductive type of ZnO thin films changed from n-type to p-type and then to n-type again. However, the solution concentration almost has no effect on the structural and electrical properties of p-type ZnO films. X-ray Photoelectron Spectroscopy indicated that the presence of Al indeed facilitates the incorporation of N through the formation of N-Al bonds in co-doped ZnO films. In addition, Photoluminescence spectra showed p-type ZnO films with a low density of native defects

2007-10-15

371

Cascade-driven migration of structural interfaces: A new type of irradiation-induced phase transformation  

International Nuclear Information System (INIS)

In Ti-Cr alloys containing both the Laves phase (ordered TiCr2) and the ? phase (bcc solid solution), 1 MeV Kr+ irradiation at temperatures <250 K amorphizes the Laves phase but not the ? phase. The irradiation-induced amorphous material transforms into polycrystalline ? upon warming to room temperature. In contrast, irradiation at room temperature causes the ? phase to grow by migration of the ?/Laves interface; no change in local composition across the migrating interface is observed. The ? phase also grows during prolonged irradiation at 100 K, but the velocity of the ?/amorphous interface per unit calculated atomic displacement rate is more than three orders of magnitude lower than that of the ?/Laves interface at room temperature. An interpretation of this new type of irradiation-induced phase transformation is presented in terms of displacement cascade formation and dynamic recovery at the structural interface that exists between the two phases

1987-06-29

372

Genetic-Structural relations in some types of spanish uranium deposits  

International Nuclear Information System (INIS)

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

1962-01-01

373

Flow simulation of a diaphragm-type ventricular assist device with structural interactions.  

Science.gov (United States)

A numerical simulation of the fluid and structure interactions was performed for a diaphragm-type Ventricular Assist Device (VAD). The simulation was included two incompressible fluids and three elastic solid regions. The detailed information of both fluid and solid dynamic are crucial to evaluate the performance of the device. Localization of potential points prone to hemolysis and thrombus formation and disturbed flow with creation of recirculation zones are vary important. Here, the HeartSaver VAD was modeled as a two dimensional chambers with an inlet and an outlet elastic valves, an elastic sac-shape membrane, driving fluid and blood. A pulsatile velocity condition was applied at the inlet of the driving fluid chamber. As the results, the flow characteristics affecting the blood cells including velocity, pressure, wall shear stress and the elastic valves operation were presented in details. PMID:18002135

Moosavi, M H; Fatouraee, N

2007-01-01

374

An effective Skyrme-type interaction for nuclear structure calculations. Pt. 1  

International Nuclear Information System (INIS)

A 'universal' effective NN interaction of the Skyrme type has been proposed which is suitable for both ground and excited states in nuclei throughout the nuclear mass table. The analytical structure of the proposed interaction SkE is presented and discussed. The spin stability of the force is studied by deriving the corresponding Landau-Migdal interaction for uniform nuclear matter. An equivalent set of force parameters starting from a realistic interaction after application of the local-density approximation (LDA) and the density-matrix expansion (DME) is derived. The behavior of the SkE interaction in describing charge properties is extensively discussed by carrying out a detailed and elaborate study of nucleon and charge distributions in _5_8Ni, the Ca and Pb isotopes. (orig.)

1983-08-08

375

The U4Re7Si6 type - Trends in electronic structure and chemical bonding  

International Nuclear Information System (INIS)

The electronic structures and chemical bonding of selected ternary compounds of the A4T7X6 family (of U4Re7Si6-type) intermetallics have been studied by ab initio methods. The calculations for two series: Mg4Rh7P6, Sc4Co7Ge6, Ti4Co7Ge6 and uranium containing U4Re7Si6, U4Ru7Ge6, and U4Ru7As6 show common bonding characteristics pertaining to main T1-X and T2-X interactions (T = transition metal and X = p-element) due to the peculiar crystal chemistry with T1(at)X6 and T2(at)X4 coordination polyhedra. The uranium compounds are found to be stabilized in a spin polarized ferromagnetic configuration, especially for U4Ru7Ge6 (in agreement with experiment) and U4Ru7As6. (authors)

2014-01-01

376

NMR study of one-dimensional ionic conductors with hollandite-type structure  

International Nuclear Information System (INIS)

Results of AC conductivity and "7Li NMR measurements are reported for Li-doped priderites with the hollandite-type structure. AC conductivities are well explained by the transport theory in the disordered one-dimensional (1D) systems. The spin-spin relaxation shows a decay of the form exp(-tsup(3/2)) characteristic of 1D diffusional motion. The temperature dependence of the spin-lattice relaxation time T_1 gives a very low activation energy due to the diffusional motion of Li"+ ions. If an enhancement factor of 3 is assumed in the 1D system, an activation energy of approximately 0.06 eV is obtained for the diffusional motion. (Auth.)

1981-08-01

377

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

International Nuclear Information System (INIS)

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

1988-01-01

378

Synthesis, structure and electrical properties of rare-earth doped apatite-type lanthanum silicates  

International Nuclear Information System (INIS)

Highlights: ? La9ASi6O27 ceramics were prepared by pressureless-sintering at 1923 K. ? La9ASi6O27 ceramics have apatite structure. ? The electrical conductivity of La9ASi6O27 increases with temperature. ? The highest conductivity is 1.03 × 10?2 S cm?1 at 1073 K for La9YbSi6O27. - Abstract: Rare-earth doped apatite-type lanthanum silicates, La9ASi6O27 (A = Nd, Sm, Gd, Yb), are synthesized by the high-temperature solid state reaction process. The microstructure and electrical properties of La9ASi6O27 ceramics are investigated by X-ray diffraction, scanning electron microscopy and complex impedance analysis. La9ASi6O27 ceramics are composed of hexagonal apatite-type structure and a very small amount of second phase La2SiO5. The total electrical conductivity of rare-earth doped lanthanum silicates obeys the Arrhenius relation, and gradually increases with increasing temperature from 673 K to 1173 K. Lanthanum silicates doped with Nd or Yb cations exhibit a higher total electrical conductivity than undoped lanthanum silicate. The highest total electrical conductivity value obtained at 773 K is 4.31 × 10?4 S cm?1 for La9NdSi6O27. At 1073 K, La9NdSi6O27 and La9YbSi6O27 have a total electrical conductivity of 8.20 × 10?3 S cm?1 and 1.03 × 10?2 S cm?1, respectively, which are distinctly higher than undoped La10Si6O27 (5.84 × 10?3 S cm?1). However, the situation is reversed when Sm or Gd rare-earth cations are doped into lanthanum silicate.

2012-03-30

379

Recombining population structure of Plesiomonas shigelloides (Enterobacteriaceae) revealed by multilocus sequence typing.  

Science.gov (United States)

Plesiomonas shigelloides is an emerging pathogen that is widespread in the aquatic environment and is responsible for intestinal diseases and extraintestinal infections in humans and other animals. Virtually nothing is known about its genetic diversity, population structure, and evolution, which severely limits epidemiological control. We addressed these questions by developing a multilocus sequence typing (MLST) system based on five genes (fusA, leuS, pyrG, recG, and rpoB) and analyzing 77 epidemiologically unrelated strains from several countries and several ecological sources. The phylogenetic position of P. shigelloides within family Enterobacteriaceae was precisely defined by phylogenetic analysis of the same gene portions in other family members. Within P. shigelloides, high levels of nucleotide diversity (average percentage of nucleotide differences between strains, 1.49%) and genotypic diversity (64 distinct sequence types; Simpson's index, 99.7%) were found, with no salient internal phylogenetic structure. We estimated that homologous recombination in housekeeping genes affects P. shigelloides alleles and nucleotides 7 and 77 times more frequently than mutation, respectively. These ratios are similar to those observed in the naturally transformable species Streptococcus pneumoniae with a high rate of recombination. In contrast, recombination within Salmonella enterica, Escherichia coli, and Yersinia enterocolitica was much less frequent. P. shigelloides thus stands out among members of the Enterobacteriaceae. Its high rate of recombination results in a lack of association between genomic background and O and H antigenic factors, as observed for the 51 serotypes found in our sample. Given its robustness and discriminatory power, we recommend MLST as a reference method for population biology studies and epidemiological tracking of P. shigelloides strains. PMID:17693512

Salerno, Anna; Delétoile, Alexis; Lefevre, Martine; Ciznar, Ivan; Krovacek, Karel; Grimont, Patrick; Brisse, Sylvain

2007-11-01

380

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

Science.gov (United States)

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

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

2011-12-01

 
 
 
 
381

Enhancing the three-dimensional electronic structure in 1111-type iron arsenide superconductors by H substitution  

Science.gov (United States)

The 1111-type iron arsenide hydride CaFe1-xCoxAsH was synthesized by high-pressure solid-state reaction, and its electronic structure and superconducting properties were investigated. Bulk superconductivity was observed at x = 0.09-0.26. A maximum superconducting critical temperature (Tcmax) of 23 K was observed at x = 0.09. These values are in agreement with those of CaFe1-xCoxAsF. The calculated Fermi surface of CaFeAsH has a small three-dimensional (3D) hole pocket around the ? point. This is a result of weak covalent bonding between the As 4p and H 1s orbitals. No such covalency exists in CaFeAsF, because the energy level of the F 2p orbital is sufficiently deep to inhibit overlap with the As 4p orbital. The similar superconductivities of CaFe1-xCoxAsH and CaFe1-xCoxAsF are explained with the nesting scenario. The small 3D hole pocket of CaFe1-xCoxAsH does not significantly contribute to electron excitation. These findings encourage exploration of hydrogen-containing 1111-type iron-based materials with lower anisotropies and higher Tc applicable to superconducting wires and tapes.

Muraba, Yoshinori; Matsuishi, Satoru; Hosono, Hideo

2014-03-01

382

Crystal structure and equation of state of cotunnite-type zirconia  

International Nuclear Information System (INIS)

Cotunnite-type zirconia was studied by angular-dispersive X-ray diffraction in a diamond anvil cell after laser heating and 18 and 26.7 GPa. The structure, space group Pnam, Z = 4, was refined in situ at several different pressures on decompression and at ambient using the Rietveld method. The nine polyhedral Zr-O distances range from 2.10 to 2.56 angstrom at ambient pressure, which represents both an increase in the average and the minimum Zr-O distance relative to the monoclinic and orthorhombic lower-pressure forms. In addition, data obtained on an unheated sample indicate that the irreversible transition to the cotunnite phase began above 25 GPa and 70% conversion was achieved by 48.5 GPa. The compressibility of cotunnite-type zirconia was found to be slightly anisotropic and a Birch-Murnaghan equation-of-state fit of the p-V data yielded a bulk modulus of 332(8) GPa with a first derivative of 2.3(4), which is in good agreement with the value predicted by previous ab initio calculations

1995-02-01

383

Structure and properties of die steels with carbon of the 5KhMNF type  

International Nuclear Information System (INIS)

A study was made of the relationship between the structure and properties of 5Kh2MNF-type steels the cooling rate after austenitization and the carbon content, the latter most heavily influencing the quenchability and quenching of steels, and, therefore, their toughness and plasticity. The most rational carbon content in the secondarily-hardened Kh2MNF-type stamp steels is 0.5%, which ensures a high heat resistance at 600 to 620 deg C; good tensile properties sigmasub(B)=145 to 150 kgs/mm2 and fracture toughness ?sub(H)=3.5 to 5.0 kgsxm/cm2 in case of circular (up to 500x500 mm) forged pieces. The 5Kh2MNF steel is recommended for large-size heavily loaded pressing and forging stamps used for hot deformation. The heat treatment conditions: quenching from 970 to 1000 deg C, cooling in oil, tempering at 580 to 620 deg C for a Rockwell hardness of 45 to 47 for the pressing stamps and 42 to 44 for the forging stamps

1975-01-01

384

Structural changes in the compounds LiM2IV(PO4)3 (MIV=Ge, Ti, Sn, and Hf) as followed by 31P and 7Li NMR  

International Nuclear Information System (INIS)

From the 31P and 7Li NMR study of the compounds LiM2(PO4)3 (MIV=Ge, Ti, Sn, and Hf), structural distortions of the NASICON (acronym for Na superionic conductors) network and the occupation of structural sites by lithium have been analyzed. In compounds with larger cations (MIV=Sn and Hf), structural distortions reduce the ideal symmetry of the NASICON framework (rhombohedral R bar 3c), producing the differentiation of three phosphorous sites. In these low-symmetry phases, PO4 tetrahedra distortions, deduced from the analysis of the 31P NMR chemical shift tensor, are higher than those of rhombohedral phases. These additional distortions are eliminated by sample heating above their corresponding transition temperature. On the other hand, from analysis of the dipole and quadrupole interactions of 7Li NMR spectra, recorded at low temperatures, it has been deduced that lithium atoms are located at M1 sites in the rhombohedral LiGe2(PO4)3 and LiTi2(PO4)3 and at M2 sites in the low-symmetry phases of LiSn2(PO4)3 and LiHf2(PO4)3 compounds. copyright 1997 The American Physical Society

1997-06-01

385

Structural changes in the compounds LiM{sub 2}{sup IV}(PO{sub 4}){sub 3} (M{sup IV}=Ge, Ti, Sn, and Hf) as followed by {sup 31}P and {sup 7}Li NMR  

Energy Technology Data Exchange (ETDEWEB)

From the {sup 31}P and {sup 7}Li NMR study of the compounds LiM{sub 2}(PO{sub 4}){sub 3} (M{sup IV}=Ge, Ti, Sn, and Hf), structural distortions of the NASICON (acronym for Na superionic conductors) network and the occupation of structural sites by lithium have been analyzed. In compounds with larger cations (M{sup IV}=Sn and Hf), structural distortions reduce the ideal symmetry of the NASICON framework (rhombohedral R{bar 3}c), producing the differentiation of three phosphorous sites. In these low-symmetry phases, PO{sub 4} tetrahedra distortions, deduced from the analysis of the {sup 31}P NMR chemical shift tensor, are higher than those of rhombohedral phases. These additional distortions are eliminated by sample heating above their corresponding transition temperature. On the other hand, from analysis of the dipole and quadrupole interactions of {sup 7}Li NMR spectra, recorded at low temperatures, it has been deduced that lithium atoms are located at M{sub 1} sites in the rhombohedral LiGe{sub 2}(PO{sub 4}){sub 3} and LiTi{sub 2}(PO{sub 4}){sub 3} and at M{sub 2} sites in the low-symmetry phases of LiSn{sub 2}(PO{sub 4}){sub 3} and LiHf{sub 2}(PO{sub 4}){sub 3} compounds. {copyright} {ital 1997} {ital The American Physical Society}

Paris, M.A.; Sanz, J. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas (CSIC), 28049 Cantoblanco, Madrid (Spain)

1997-06-01

386

Multilocus Fragment Typing and Genetic Structure of Cryptosporidium parvum Isolates from Diarrheic Preweaned Calves in Spain?  

Science.gov (United States)

A collection of 140 Cryptosporidium parvum isolates previously analyzed by PCR-restriction fragment length polymorphism (PCR-RFLP) and sequence analyses of the small-subunit (SSU) rRNA and 60-kDa glycoprotein (GP60) genes was further characterized by multilocus fragment typing of six minisatellite (MSB and MS5) and microsatellite (ML1, ML2, TP14, and 5B12) loci. Isolates were collected from diarrheic preweaned calves originating from 61 dairy cattle farms in northern Spain. A capillary electrophoresis-based tool combining three different fluorescent tags was used to analyze all six satellites in one capillary. Fragment sizes were adjusted after comparison with sizes obtained by sequence analysis of a selection of isolates for every allele. Size discrepancies at all but the 5B12 locus were found for those isolates that were typed by both techniques, although identical size differences were reported for every allele within each locus. A total of eight alleles were seen at the ML2 marker, which contributed the most to the discriminatory power of the multilocus approach. Multilocus fragment typing clearly improved the discriminatory power of GP60 sequencing, since a total of 59 multilocus subtypes were identified based on the combination of alleles at the six satellite loci, in contrast to the 7 GP60 subtypes previously reported. The majority of farms (38) displayed a unique multilocus subtype, and individual isolates with mixed multilocus subtypes were seen at 22 farms. Bayesian structure analysis based on combined data for both satellite and GP60 loci suggested the presence of two major clusters among the C. parvum isolates from cattle farms in this geographical area.

Quilez, Joaquin; Vergara-Castiblanco, Claudia; Monteagudo, Luis; del Cacho, Emilio; Sanchez-Acedo, Caridad

2011-01-01

387

Multilocus fragment typing and genetic structure of Cryptosporidium parvum Isolates from diarrheic preweaned calves in Spain.  

Science.gov (United States)

A collection of 140 Cryptosporidium parvum isolates previously analyzed by PCR-restriction fragment length polymorphism (PCR-RFLP) and sequence analyses of the small-subunit (SSU) rRNA and 60-kDa glycoprotein (GP60) genes was further characterized by multilocus fragment typing of six minisatellite (MSB and MS5) and microsatellite (ML1, ML2, TP14, and 5B12) loci. Isolates were collected from diarrheic preweaned calves originating from 61 dairy cattle farms in northern Spain. A capillary electrophoresis-based tool combining three different fluorescent tags was used to analyze all six satellites in one capillary. Fragment sizes were adjusted after comparison with sizes obtained by sequence analysis of a selection of isolates for every allele. Size discrepancies at all but the 5B12 locus were found for those isolates that were typed by both techniques, although identical size differences were reported for every allele within each locus. A total of eight alleles were seen at the ML2 marker, which contributed the most to the discriminatory power of the multilocus approach. Multilocus fragment typing clearly improved the discriminatory power of GP60 sequencing, since a total of 59 multilocus subtypes were identified based on the combination of alleles at the six satellite loci, in contrast to the 7 GP60 subtypes previously reported. The majority of farms (38) displayed a unique multilocus subtype, and individual isolates with mixed multilocus subtypes were seen at 22 farms. Bayesian structure analysis based on combined data for both satellite and GP60 loci suggested the presence of two major clusters among the C. parvum isolates from cattle farms in this geographical area. PMID:21908632

Quílez, Joaquín; Vergara-Castiblanco, Claudia; Monteagudo, Luis; Del Cacho, Emilio; Sánchez-Acedo, Caridad

2011-11-01

388

Structure-toxicity analysis of type-2 alkenes: in vitro neurotoxicity.  

Science.gov (United States)

Acrylamide (ACR) is a conjugated type-2 alkene that produces synaptic toxicity presumably by sulfhydryl adduction. The alpha,beta-unsaturated carbonyl of ACR is a soft electrophile and, therefore, adduction of nucleophilic thiol groups could occur through a conjugate (Michael) addition reaction. To address the mechanism of thiol adduct formation and corresponding neurotoxicological importance, we defined structure-toxicity relationships among a series of conjugated type-2 alkenes (1 microM-10mM), which included acrolein and methylvinyl ketone. Results show that exposure of rat striatal synaptosomes to these chemicals produced parallel, concentration-dependent neurotoxic effects that were correlated to loss of free sulfhydryl groups. Although differences in relative potency were evident, all conjugated analogs tested were equiefficacious with respect to maximal neurotoxicity achieved. In contrast, nonconjugated alkene or aldehyde congeners did not cause synaptosomal dysfunction or sulfhydryl loss. Acrolein and other alpha,beta-unsaturated carbonyls are bifunctional (electrophilic reactivity at the C-1 and C-3 positions) and could produce in vitro neurotoxicity by forming protein cross-links rather than thiol monoadducts. Immunoblot analysis detected slower migrating, presumably derivatized, synaptosomal proteins only at very high acrolein concentrations (>or= 25 mM). Exposure of synaptosomes to high concentrations of ACR (1M), N-ethylmaleimide (10mM), and methyl vinyl ketone (MVK) (100mM) did not alter the gel migration of synaptosomal proteins. Furthermore, hydralazine (1mM), which blocks the formation of protein cross-links, did not affect in vitro acrolein neurotoxicity. Thus, type-2-conjugated alkenes produced synaptosomal toxicity that was linked to a loss of thiol content. This is consistent with our hypothesis that the mechanism of ACR neurotoxicity involves formation of Michael adducts with protein sulfhydryl groups. PMID:17023561

Lopachin, Richard M; Barber, David S; Geohagen, Brian C; Gavin, Terrence; He, Deke; Das, Soma

2007-01-01

389

Analysis of the population structure of Anaplasma phagocytophilum using multilocus sequence typing.  

Science.gov (United States)

Anaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium that replicates in neutrophils. It is transmitted via tick-bite and causes febrile disease in humans and animals. Human granulocytic anaplasmosis is regarded as an emerging infectious disease in North America, Europe and Asia. However, although increasingly detected, it is still rare in Europe. Clinically apparent A. phagocytophilum infections in animals are mainly found in horses, dogs, cats, sheep and cattle. Evidence from cross-infection experiments that A. phagocytophilum isolates of distinct host origin are not uniformly infectious for heterologous hosts has led to several approaches of molecular strain characterization. Unfortunately, the results of these studies are not always easily comparable, because different gene regions and fragment lengths were investigated. Multilocus sequence typing is a widely accepted method for molecular characterization of bacteria. We here provide for the first time a universal typing method that is easily transferable between different laboratories. We validated our approach on an unprecedented large data set of almost 400 A. phagocytophilum strains from humans and animals mostly from Europe. The typability was 74% (284/383). One major clonal complex containing 177 strains was detected. However, 54% (49/90) of the sequence types were not part of a clonal complex indicating that the population structure of A. phagocytophilum is probably semiclonal. All strains from humans, dogs and horses from Europe belonged to the same clonal complex. As canine and equine granulocytic anaplasmosis occurs frequently in Europe, human granulocytic anaplasmosis is likely to be underdiagnosed in Europe. Further, wild boars and hedgehogs may serve as reservoir hosts of the disease in humans and domestic animals in Europe, because their strains belonged to the same clonal complex. In contrast, as they were only distantly related, roe deer, voles and shrews are unlikely to harbor A. phagocytophilum strains infectious for humans, domestic or farm animals. PMID:24699849

Huhn, Christian; Winter, Christina; Wolfsperger, Timo; Wüppenhorst, Nicole; Strašek Smrdel, Katja; Skuballa, Jasmin; Pfäffle, Miriam; Petney, Trevor; Silaghi, Cornelia; Dyachenko, Viktor; Pantchev, Nikola; Straubinger, Reinhard K; Schaarschmidt-Kiener, Daniel; Ganter, Martin; Aardema, Matthew L; von Loewenich, Friederike D

2014-01-01

390

Analysis of the Population Structure of Anaplasma phagocytophilum Using Multilocus Sequence Typing  

Science.gov (United States)

Anaplasma phagocytophilum is a Gram-negative obligate intracellular bacterium that replicates in neutrophils. It is transmitted via tick-bite and causes febrile disease in humans and animals. Human granulocytic anaplasmosis is regarded as an emerging infectious disease in North America, Europe and Asia. However, although increasingly detected, it is still rare in Europe. Clinically apparent A. phagocytophilum infections in animals are mainly found in horses, dogs, cats, sheep and cattle. Evidence from cross-infection experiments that A. phagocytophilum isolates of distinct host origin are not uniformly infectious for heterologous hosts has led to several approaches of molecular strain characterization. Unfortunately, the results of these studies are not always easily comparable, because different gene regions and fragment lengths were investigated. Multilocus sequence typing is a widely accepted method for molecular characterization of bacteria. We here provide for the first time a universal typing method that is easily transferable between different laboratories. We validated our approach on an unprecedented large data set of almost 400 A. phagocytophilum strains from humans and animals mostly from Europe. The typability was 74% (284/383). One major clonal complex containing 177 strains was detected. However, 54% (49/90) of the sequence types were not part of a clonal complex indicating that the population structure of A. phagocytophilum is probably semiclonal. All strains from humans, dogs and horses from Europe belonged to the same clonal complex. As canine and equine granulocytic anaplasmosis occurs frequently in Europe, human granulocytic anaplasmosis is likely to be underdiagnosed in Europe. Further, wild boars and hedgehogs may serve as reservoir hosts of the disease in humans and domestic animals in Europe, because their strains belonged to the same clonal complex. In contrast, as they were only distantly related, roe deer, voles and shrews are unlikely to harbor A. phagocytophilum strains infectious for humans, domestic or farm animals.

Huhn, Christian; Winter, Christina; Wolfsperger, Timo; Wuppenhorst, Nicole; Strasek Smrdel, Katja; Skuballa, Jasmin; Pfaffle, Miriam; Petney, Trevor; Silaghi, Cornelia; Dyachenko, Viktor; Pantchev, Nikola; Straubinger, Reinhard K.; Schaarschmidt-Kiener, Daniel; Ganter, Martin; Aardema, Matthew L.; von Loewenich, Friederike D.

2014-01-01

391

A strategy for depositing different types of cells in three dimensions to mimic tubular structures in tissues.  

Science.gov (United States)

The fabrication of tubular structures, with multiple cell types forming different layers of the tube walls, is described using a stress-induced rolling membrane (SIRM). Cell orientation inside the tubes can also be controlled by topographical contact guidance. These layered tubes precisely mimic blood vessels and many other tubular structures, suggesting that they may be of great use in tissue engineering. PMID:22403828

Yuan, Bo; Jin, Yu; Sun, Yi; Wang, Dong; Sun, Jiashu; Wang, Zhuo; Zhang, Wei; Jiang, Xingyu

2012-02-14

392

Cloud cover typing from environmental satellite imagery. Discriminating cloud structure with Fast Fourier Transforms (FFT)  

Science.gov (United States)

The use of two dimensional Fast Fourier Transforms (FFTs) subjected to pattern recognition technology for the identification and classification of low altitude stratus cloud structure from Geostationary Operational Environmental Satellite (GOES) imagery was examined. The development of a scene independent pattern recognition methodology, unconstrained by conventional cloud morphological classifications was emphasized. A technique for extracting cloud shape, direction, and size attributes from GOES visual imagery was developed. These attributes were combined with two statistical attributes (cloud mean brightness, cloud standard deviation), and interrogated using unsupervised clustering amd maximum likelihood classification techniques. Results indicate that: (1) the key cloud discrimination attributes are mean brightness, direction, shape, and minimum size; (2) cloud structure can be differentiated at given pixel scales; (3) cloud type may be identifiable at coarser scales; (4) there are positive indications of scene independence which would permit development of a cloud signature bank; (5) edge enhancement of GOES imagery does not appreciably improve cloud classification over the use of raw data; and (6) the GOES imagery must be apodized before generation of FFTs.

Logan, T. L.; Huning, J. R.; Glackin, D. L.

1983-01-01

393

NdNiMg5, a new magnesium-rich phase with an unusual structural type.  

Science.gov (United States)

The new intermetallic NdNiMg5 was discovered during the study of the Mg-rich part of the Mg-Nd-Ni system. It was synthetized by melting of the constituent elements in a sealed tantalum tube with subsequent annealing. Its structure was determined by X-ray diffraction on a single crystal. Crystal data: orthorhombic system, Cmcm, Z = 4, a = 4.4799(2) Å, b = 9.9827(3) Å, c = 13.7854(10) Å, d(calc) = 3.49 g·cm(-3). Its structure is made of infinite layers of Mg atoms that form blocks stacked along the c axis. These blocks, with a close-packed array of Mg atoms, are separated by infinite NiNd layers and connected through short Mg-Mg bonds. In the NiNd layer, the Ni and Nd atoms form an ordered graphite-type network. Antiferromagnetic ordering is observed with T(N) = 12 K, and the effective magnetic moment ?eff is equal to 3.89(1) ?B. PMID:24224857

Ourane, Bassem; Gaudin, Etienne; Zouari, Ridha; Couillaud, Samuel; Bobet, Jean-Louis

2013-12-01

394

The Russian oil industry re-structuration: towards the emergence of western type enterprises?  

Energy Technology Data Exchange (ETDEWEB)

The Russian oil industry has undergone fundamental changes since the collapse of the Soviet Empire and its bureaucratic administrative structure, dominated by its various Branch Ministries. The monopoly in the Soviet oil industry has now been replaced by a number of ''oil companies'', some of which are very powerful, the best known of them being Lukoil. These ''joint stock companies'' are the product of a reform aimed essentially at implanting, out of all the numerous organisational arrangements developed in the West, the model of the vertically integrated private firm. Beyond the legal reforms in the Russian oil industry sector, however, the nature of the organisational model that has actually emerged in Russia begs several questions. Many entities, which are complex and highly diversified, are involved in this industry. There are, of course, the many private structures in which the banks sometimes carry a considerable amount of weight. There are also some vertically integrated organisations, but the degree of integration is variable and their method of centralization is based on a specific form of economic logic. It should not be considered, however, that these actors are similar to capitalist-type private enterprises, whose behaviour is regulated by the demands of international competition. Reform of property rights has not been sufficient to create true private enterprise in Russia. (author)

Locatelli, C

1999-01-01

395

A COMPARISON OF TWO THERMAL INSULATION AND STRUCTURAL MATERIALS FOR USE IN TYPE B PACKAGINGS  

Energy Technology Data Exchange (ETDEWEB)

This paper presents the summary of design features and test results of two Type B Shipping Package prototype configurations comprising different insulating materials developed by the Savannah River National Laboratory (SRNL) for the Department of Energy. The materials evaluated, a closed-cell polyurethane foam and a vacuformed ceramic fiber material, were selected to provide adequate structural protection to the package containment vessel during Normal Conditions of Transport (NCT) and Hypothetical Accident Condition (HAC) events and to provide thermal protection during the HAC fire. Polyurethane foam has been used in shipping package designs for many years because of the stiffness it provides to the structure and because of the thermal protection it provides during fire scenarios. This comparison describes how ceramic fiber material offers an alternative to the polyurethane foam in a specific overpack design. Because of the high operating temperature ({approx}2,300 F) of the ceramic material, it allows for contents with higher heat loads to be shipped than is possible with polyurethane foam. Methods of manufacturing and design considerations using the two materials will be addressed.

Blanton, P.; Eberl, K.

2010-07-16

396

Structural and phase transformations in the low-temperature annealed amorphous “finemet”-type microwires  

International Nuclear Information System (INIS)

Highlights: • Structure and magnetic properties evolution at heating of amorphous microwires was studied. • Relaxation processes in the amorphous phase correlate with an increase in Curie temperature. • Curie temperature change can not be stabilized by a prolonged exposure at pre-crystallization temperatures. • Tomographic atom probe microscopy supports the formation of ?-Fe phase precipitations enriched in Si. -- Abstract: Finemet-type glass-coated microwires with amorphous and nanocrystalline structure have been investigated. The relaxation and crystallization processes at heating of amorphous alloy have been studied by DSC method. We observed that the relaxation processes in the amorphous phase correlate with an increasing of the Curie temperature. Additionally a prolonged exposure of the samples below the crystallization temperatures does not stabilize the Curie temperature change. An investigation by the tomographic atom probe microscopy supports the formation of precipitations, probably ?-Fe phase, as a result of low-temperature annealing (400 °C, 5 min). We found that the observed nano-sized areas were enriched in silicon

2014-02-15

397

Electrical and structural properties of p -type nanocrystalline silicon grown by LEPECVD for photovoltaic applications  

Energy Technology Data Exchange (ETDEWEB)

p-doped hydrogenated nanocrystalline silicon (p-nc-Si:H) is one of the most critical layers in thin film silicon solar cells. LEPECVD is a new technique for the growth of nc-Si at high growth rate without compromising the layer quality, using a dense but low energy plasma. Thin p-nc-Si:H layers are grown on glass and ZnO:Al coated glass and their structural and electrical properties are investigated as a function of the silane dilution (d) and of the doping ratio (DR). The influence of the substrate on the structural properties is investigated and discussed. The incubation layer is clearly observed on both substrate types and its thickness is estimated. LEPECVD distinguishes itself from other high growth rate methods by a very low impurity distribution coefficient to obtain a comparable conductivity and boron density. The conduction path is shown to be dependent on the density of boron in the layer while a significant decrease of conductivity at high DR is not observed in the studied range (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Micard, Gabriel; Hahn, Giso; Terheiden, Barbara [Department of Physics, Faculty of Sciences, University of Konstanz (Germany); Chrastina, Daniel; Isella, Giovanni; Moiseev, Tamara [L-NESS, Dipartimento di Fisica del Politecnico di Milano, Polo Regionale di Como (Italy); Cavalcoli, Daniela; Cavallini, Anna [Department of Physics, University of Bologna (Italy); Binetti, Simona; Acciarri, Maurizio; Le Donne, Alessia [Dipartimento di Scienza dei Materiali, Universita di Milano-Bicocca, Milano (Italy); Texier, Michael [Institut Materiaux, Microelectronique, Nanosciences de Provence (IM2NP UMR 6242) Fac. Sciences et Techniques de Saint Jerome, Marseille (France); Pichaud, Bernard [Institut Materiaux, Microelectronique, Nanosciences de Provence (IM2NP UMR 6242) Fac. Sciences et Techniques de Saint Jerome, Marseille (France)

2010-04-15

398

Temperature-dependent structural studies of mullite-type Bi2Fe4O9  

Science.gov (United States)

We report on the temperature-dependent structural studies on the mullite-type Bi2Fe4O9 compound. The crystal structures were determined using both powder X-ray diffraction and single crystal neutron diffraction. The thermal expansion of the cell parameters from smallest to largest occurred in the order aBi3+ 6s2 lone electron pair was probed by the absolute value of eccentricity parameter. This parameter shows a significant drop at around 773 K. Additionally, the average crystal size and micro-strain of the powder samples were studied. A healing of intrinsic defects is observed with respect to a decreasing micro-strain followed by crystal growth above about 900 K. The temperature-dependent infrared spectra were described in three distinct zones. Deconvolution of the absorption features between 370 cm-1 and 1000 cm-1 required nine fitted bands, and the decomposed Pseudo-Voigt elements were assigned to Fe-O stretching, Fe-O-Fe bending and O-Fe-O bending vibrations. The shift of the observed modes was described with respect to temperature. An effective linewidth parameter ?corr was determined by autocorrelation analysis between 740 cm-1 and 900 cm-1 for each temperature-dependent spectrum. The break of the slope of ?corr at about 773 K was interpreted as the change of some vibrational modes of the FeO4 tetrahedra. The intrinsic effects observed around 773 K are responsible for extrinsic parameter changes found around 900 K.

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

2013-01-01

399

Low-dark current structures for long-wavelength Type-II strained layer superlattice photodiodes  

Science.gov (United States)

This paper describes our efforts on the development of low dark current long-wave infrared (LWIR) photodetectors based on type-II InAs/GaSb strained superlattices. By adopting a so-called pBiBn structure, a hybrid between the conventional PIN structure and unipolar barrier concepts, suppressed dark current and near-zero-bias operation are obtained, respectively. The LWIR photodetector has a dark current density as low as 1.42×10-5 A/cm2 at -60 mV, and R0A of 5365 ?cm2 at 76 K. The measured peak detectivity at 10.2 µm of 8.7×1010 cmHz1/2W-1 is obtained at -60 mV at 76 K. To further improve the device performances, a newer design with longer cut-off wavelength targeted for near zero-bias was also realized. This 2-µm-thick device exhibits a quantum efficiency of 20% at 10 µm under zero-bias.

Tian, Zhaobing; DeCuir, Eric A.; Wijewarnasuriya, Priyalal S.; Pattison, James W.; Gautam, Nutan; Krishna, Sanjay; Dhar, Nibir; Welser, Roger E.; Sood, Ashok K.

2013-06-01

400

Structural controls on Carlin-type gold mineralization in the gold bar district, Eureka County, Nevada  

Science.gov (United States)

The Gold Bar district in the southern Roberts Mountains, 48 km northwest of Eureka, Nevada, contains one main deposit (Gold Bar), five satellite deposits, and other resources. Approximately 0.5 Moz of gold have been recovered from a resource of 1,639,000 oz of gold in Carlin-type gold deposits in lower plate, miogeoclinal carbonate rocks below the Roberts Mountains thrust. Host rocks are unit 2 of the Upper Member of the Devonian Denay Formation and the Bartine Member of the McColley Canyon Formation. Spatial and temporal relations between structures and gold mineralization indicate that both pre-Tertiary and Tertiary structures were important controls on gold mineralization. Gold mineralization occurs primarily along high-angle Tertiary normal faults, some of which are reactivated reverse faults of Paleozoic or Mesozoic age. Most deposits are localized at the intersection of northwest- and northeast-striking faults. Alteration includes decalcification, and to a lesser extent, silicification along high-angle faults. Jasperoid (pervasive silicification), which formed along most faults and in some strata-bound zones, accounts for a small portion of the ore in every deposit. In the Gold Canyon deposit, a high-grade jasperoid pipe formed along a Tertiary normal fault which was localized along a zone of overturned fault-propagation folds and thrust faults of Paleozoic or Mesozoic age.

Yigit, O.; Nelson, E. P.; Hitzman, M. W.; Hofstra, A. H.

2003-01-01