Anomalous X-ray scattering study of local structures in the superionic conducting class (CuI)(0.3)(Cu2O)(0.35)(MoO3)(0.35)

The anomalous X-ray scattering (AXS) method using Cu and Mo K absorption edges has been employed for obtaining the local structural information of superionic conducting glass having the composition (CuI)(0.3)(Cu2O)(0.35)(MoO3)(0.35). The possible atomic arrangements in near-neighbor region of this glass were estimated by coupling the results with the least-squares analysis so as to reproduce two differential intensity profiles for Cu and Mo as well as the ordinary scattering profile. The coordination number of oxygen around Mo is found to be 6.1 at the distance of 0.187 nm. This implies that the MoO6 octahedral unit is a more probable structural entity in the glass rather than MoO4 tetrahedra which has been proposed based on infrared spectroscopy. The pre-peak shoulder observed at about 10 nm(-1) may be attributed to density fluctuation originating from the MoO6 octahedral units connected with the corner sharing linkage, in which the correlation length is about 0.8 nm. The value of the coordination number of I- around Cu+ is estimated as 4.3 at 0.261 nm, suggesting an arrangement similar to that in molten CuI.

A study of the influence of mischmetal additions to Al-7Si-0.3Mg (LM 25/356) alloy

This article deals with the effect of 0.25-1.5 wt pct mischmetal (MM) addition on the mechanical properties, microstructure, electrical conductivity, and fracture behavior of cast Al-7Si-0.3Mg (LM 25/356) alloy. Modification of eutectic silicon by MM is compared with strontium modification in terms of microstructure, mechanical properties, and fading behavior. Loss of magnesium encountered on holding the molten alloy and its resultant effect on mechanical properties of alloys modified with MM and Sr are compared with those in the unmodified alloy.

Azidothymidine induces apoptosis in mouse myeloma cell line Sp2/0

Azidothymidine (AZT), which has been extensively used as an antiviral agent in the treatment of AIDS, showed strong inhibition of growth of Sp2/0 cells in vitro. AZT-treated cells showed a decrease in viability in a dose-dependent manner. AZT specifically induced typical apoptotic cell death with DNA double-strand cleavage and subsequent formation of apoptotic bodies. The induction of DNA double-strand cleavage into the oligonucleosomal ladder by AZT was protected in the presence of thymidine or uridine. An increase in endonuclease activity from nuclear extract of AZT-treated cells was observed. The enzyme activity was found to be Ca2+- and Mg2+-dependent and was inhibited by zinc acetate. A marked enhancement of PARP activity was observed in AZT-treated cells. These observations show that AZT can trigger both morphological and biochemical changes typical of apoptosis in the mouse myeloma cell line Sp2/0.

Neutron diffraction study of the coupling between spin, lattice, and structural degrees of freedom in 0.8BiFeO(3)-0.2PbTiO(3)

A powder neutron diffraction study was carried out on 0.8BiFeO(3)-0.2PbTiO(3) in the temperature range 27-1000 degrees C. The system exhibits magnetic transition at similar to 300 degrees C and a rhombohedral (R3c)-cubic (Pm3m) ferroelectric phase transition at similar to 650 degrees C. Anomalous variation in the lattice parameters and the octahedral tilt angle is observed across the magnetic transition temperature. In the magnetic phase, the c parameter is contracted and the octahedral tilt angle is slightly increased. The results suggest coupling between the spin, lattice and structural degrees of freedom. (C) 2011 American Institute of Physics. doi:10.1063/1.3555093]

Enantioselective synthesis of both (+)- and (-)-derivatives of bicyclo[4.3.0]nonan-8-one and 3,8-diones from R-carvone

Enantioselective synthesis of both the enantiomeric forms of the hydrindane derivatives mentioned in the title, potential chiral precursors in terpenoid synthesis, starling from R-carvone employing two different cyclopentannulation methodologies is described.

Characterization of hot deformation behaviour of Zr---2.5Nb---0.5Cu using processing maps

The characteristics of hot deformation of beta-quenched Zr-2.5Nb-0.5Cu in the temperature range 650-1050 degrees C and in the strain rate range 0.001-100 s(-1) have been studied using hot compression testing. For this study, the approach of processing maps has been adopted and their interpretation done using the Dynamic Materials Model. The efficiency of power dissipation given by [2m/(m + 1)], where m is strain rate sensitivity, is plotted as a function of temperature and strain rate to obtain a processing map. The processing map for Zr-2.5Nb-0.5Cu within (alpha + beta) phase field showed a domain of dynamic recrystallization, occurring by shearing of alpha-platelets followed by spheroidization, with a peak efficiency of 48% at 750 degrees C and 0.001 s(-1). The stress-strain curves in this domain had features of continuous flow softening and all these are similar to that in Zr-2.5Nb alloy. In the beta-phase field, a second domain with a peak efficiency of 47% occurred at 1050 degrees C and 0.001 s(-1) and this domain is correlated with the superplasticity of beta-phase. The beta-deformation characteristics of this alloy are similar to that observed in pure beta-zirconium with large grain size. Analysis of flow instabilities using a continuum criterion revealed that the Zr-2.5Nb-0.5Cu exhibits flow localization at temperatures higher than 800 degrees C and strain rates higher than about 30 s(-1) and that the addition of copper to Zr-2.5Nb reduces its susceptibility to flow instability, particularly in the (alpha + beta) phase field.

H-1 MAS NMR study of protonic conduction in layered HNbWO6 center dot xH(2)O (x=1.5, 0.5)

H-1 Magic Angle Spinning (MAS) NMR of layered HNbWO6 . xH(2)O (x = 1.5, 0.5) is carried out at room temperature and at various spinning speeds (1-12 kHz). Results on the fully hydrated sample (x = 1.5) are consistent with the model of diffusion of H3O+ ions within the layers. In the partially dehydrated sample (x = 0.5) an exchange between the distinctly present cage protons and H3O+ protons leads to protonic conduction.

Quantum corrections to the conductivity in a perovskite oxide: A low-temperature study of LaNi1-xCoxO3 (0?x?0.75)

In this paper we propose to study the evolution of the quantum corrections to the conductivity in an oxide system as we approach the metal-insulator (M-I) transition from the metallic side. We report here the measurement of the low-temperature (0.1 K0.65), m takes on large values and ?(0)=0. We explain the temperature dependence of ?(T), for T<2 K, on the metallic side (x?0.4), as arising predominantly from electron-electron interactions, taking into account the diffusion-channel contribution (which gives m=0.5) as well as the Cooper-channel contribution. In this regime, the correction to conductivity, ??(T), is a small fraction of ?(T). However, as the M-I transition is approached (x?xc), ??(T) starts to dominate ?(T) and the above theories fail to explain the observed ?(T).

Dielectric function and optical conductivity of TiOx (0.8

Reflection electron energy-loss spectra are reported for the family of compounds TiOx over the entire homogeneity range (0.8 < a: < 1.3). The spectra exhibit a plasmon feature on the low-energy side, while several interband transitions are prominent at higher energies. The real and imaginary parts of dielectric functions and optical conductivity for these compounds are determined using the Kramers-Kronig analysis. The results exhibit systematic behavior with varying oxygen stoichiometry.

Structural and vibrational studies of the layered structure solid Fe1 ? xNixPS3 (1 greater-or-equal, slanted x greater-or-equal, slanted 0)

We report here the results of structural and vibrational studies on the solid solution Fe1 ? xNixPS3 (1 greater-or-equal, slanted x greater-or-equal, slanted 0) systems. From the structural analysis, we show that there is a lattice compaction as the composition x is varied from 0 to 1, the basic lattice symmetry being maintained. We find that the compaction is more in the basal plane. These subtle structural changes are also reflected in the vibrational bands. We observed splitting of certain bands due to these small changes in the lattice constants, which we explained as arising from a correlation splitting. These changes in the vibrational bands have also been seen on cooling where there is a preferential thermal compaction in the basal plane compared to that perpendicular to the plane.

Superconductivity of La2?ySryCu1?xNixO4+? (y = 0.1, 0.2; 0less-than-or-equals, slantxless-than-or-equals, slant0.5) The hole-compensating effect of Ni

Magnetization measurements below 50 K on ceramic La2?ySryCu1?xNixO4+? (y = 0.1, 0.2; 0less-than-or-equals, slantxless-than-or-equals, slant0.5) show a progressive diminution of superconducting properties with increasing x. The larger suppressive action of Ni in the y=0.1 system than that for y=0.2 is attributed to the hole-compensating effect of Ni3+. The assumption that nickel is in the 3+ state satisfactorily explains: (1) the reduction in hole concentration, (2) a right-shift of the Tc versus y curve with x, and (3) the low magnetic moment carried by Ni atoms, in the La2?ySryCu1?xNixO4+? system.

The formation of ?-FeSiAl5 and Be---Fe phases in Al---7Si---0.3Mg alloy containing Be

Thermal analysis and interrupted quench experiments have been carried out to study the formation of beta-FeSiAl5 and (Be-Fe)-BeSiFe2Al8 phases in Al-7Si-0.3Mg alloy with and without Be addition. In the base alloy with 0.6% Fe (without Be addition), a needle- and plate-shaped beta-phase is present in the interdendritic regions and is formed by a ternary eutectic reaction. In the Be- added alloy with 0.6% Fe, a Be-Fe phase of Chinese script and polygon shapes grows along with the primary alpha-Al dendrites, leading to superior mechanical properties. It is proposed that this Be-Fe phase is formed by a peritectic reaction. Be addition has also resulted in some grain refinement.

Oxidation of methanol on the surfaces of model Cu/ZnO catalysts containing Cu1+ and Cu-0 species

Interaction of CH3OH with Cu clusters deposited on ZnO films grown on a Zn foil as well as on a ZnO(0001)Zn crystal, has been examined by X-ray photoelectron spectroscopy. On clean Cu clusters, reversible molecular adsorption or formation of CH3O is observed. However if the Cu clusters are pretreated with oxygen, both CH3O and HCOO- species are produced. Model Cu/ZnO catalyst surfaces, containing both Cu1+ and Cu-0 species, show interesting oxidation properties. On a Cu-0-rich catalyst surface, only CH3O species is formed on interaction with CH3OH. On a Cu1+-rich surface, however, HCOO- ion is the predominant species.

Preparation and characterization of Cd(0.75)PS(3)A(0.5)(H2O)(y) [A = Na, K and Cs]

Cd(0.75)PS(3)A(0.5)(H2O)(y) [A = Na, K and Cs], synthesized by the ion-exchange intercalation reaction of the insulating layered CdPS3, exhibits interesting electrical properties. The electrical properties are strongly dependent on the extent of hydration of the alkali ion which resides in the interlamellar space. In the potassium and caesium ion-exchanged compounds, y = I, the lattice expansion is similar to 3 Angstrom and the electric response characteristic of a dielectric. In the as prepared A = Na compound, y = 2, the lattice expansion is 5.6 Angstrom, the compound is conducting with a DC conductance of 3 x 10(-5) S cm(-1) at 300 K. Cd0.75PS3Na0.5(H2O)(y), y = 2, on evacuation or on heating looses water, reversibly, to form a y = 1 phase with electrical properties similar to that of the K and Cs ion exchange intercalation compounds.