A comparison of the effect of rare earth vs Si site doping on the conductivities of apatite-type rare earth silicates

Apatite-type lanthanum silicate (La_9.33Si₆O₂₆) has been attracting significant recent interest due to its high oxide ion conductivity. In this paper, synthesis and conductivity data for a range of doped samples (Mg, Ca, Sr, Ba, B, Ga and Zn) are reported, in particular, to compare the effect of rare earth vs Si site doping. The results show that Ga, B and Zn favour substitution on the Si site, while Ca, Sr and Ba favour La-site substitution. Mg is shown to be an ambi-site dopant, substituting on either site depending on the starting composition. The samples doped on the Si site show higher conductivities than comparable samples doped on the La site, providing further support for the importance of the silicate network in the conduction process, as initially predicted by atomistic modelling studies. For Ga doping on the Si site, the effect of varying the rare-earth size on the conductivities is also reported.     

Total synthesis of the novel NF-kappaB inhibitor (-)-cycloepoxydon

An enantioselective total synthesis of the novel, biologically active epoxyquinone natural product (-)-cycloepoxydon has been accomplished from the readily available Diels-Alder adduct of cyclopentadiene and p-benzoquinone. A new cycloepoxydon related heptacyclic dimer has been prepared and characterized. [reaction: see text]     

Elastic properties of mono- and poly-crystalline PbO-type FeSe1−xTex (x = 0–1.0): A first-principles study

The structural parameters of the alloys are obtained as non-magnetic cases for which justification is provided. The elastic coefficients and various moduli of the monocrystalline FeSe_1−xTe_x system as a function of doping are predicted for the first time using density functional method. The bulk moduli, shear moduli, Young’s moduli, Poisson’s ratios, velocities of sound and Debye temperature of the corresponding poly-crystalline aggregates have been calculated and the results discussed.     

Synthesis of Substituted Pyridyl‐Pyrimidines as Potential Protein–Protein Interaction Inhibitors

An efficient synthetic method for the preparation of pyridyl‐pyrimidines as potential inhibitors of protein–protein interactions is described. The key transformation is the reaction of a pyrimidine enaminone with phenyl ethyl acetate and NH⁴OAc to yield the desired pyridyl‐pyrimidine.     

Oxidation of organic compounds by hydrogen peroxide using polymer-anchored azo-metal catalysts

Polymer-anchored azo complexes of Cu(II) and Ni(II) were synthesized by the reaction of chloromethylated polystyrene, 3-aminophenol, and 1-nitroso-2-naphthol with the metal chlorides. The catalytic activities of these complexes were studied in the oxidation of various organic substrates including alkenes, alcohols, alkanes, and sulfides with 30 % aqueous hydrogen peroxide. The structures of both catalysts have been investigated by physiochemical methods. Both catalysts proved to be very stable and could be reused more than five times without significant loss of activity. Furthermore, these catalysts require very mild reaction conditions.     

Inhibition of Culex quinquefasciatus (Diptera: Culicidae) viability by nanosecond pulsed electric field radiation

Radiation effects of high-intensity nanosecond pulsed electric fields on the viability of Culex quinquefasciatus (Diptera: Culicidae) were determined. Statistical analyses from results show that the treatment energy density of up to 17.76 J m^?3 produced the optimum result in which the number of survived mosquitoes was decreased by 20% (P < 0.05). Furthermore, the average developmental rate into adult forms of treated fourth-instart lavae was found lower compared to that of the control (P < 0.05). The present study indicates that electrical pulse characteristics, especially the pulse amplitude, might be responsible for the decrease in mosquito viability.     

Effect of residual Doppler averaging on the probe absorption in cascade type system: A comparative study

Effect of residual Doppler averaging on the probe absorption in an alkali vapor medium in the presence of a coherent pump beam is studied analytically for the Ξ type system. A coherent probe field is assumed to connect the ground level with the intermediate level whereas a coherent control beam is supposed to act between the intermediate energy level and the uppermost level. Optical Bloch equations(OBE) for a three-level Ξ type system and a four-level Ξ type system are derived by using density matrix formalism. These equations are solved by an analytic method to determine the probe response, which not only depends on the wavelength difference between the control(pump) field and the probe field but shows substantially different features depending on whether the wavelength of the control field is greater than that of the probe field or the reverse. The effect of temperature on probe response is also shown. Enhancement in probe absorption and additional features are noticed under a strong probe limit at room temperature. The four-level Ξ type system has two ground levels and this leads to substantial modification in the simulated probe absorption as compared to the three-level system.     

Use of a recyclable poly(<Emphasis Type="Italic">N</Emphasis>-vinyl carbazole) palladium(II) complex catalyst: Heck cross-coupling reaction under phosphine-free and aerobic conditions

A poly(3,6-dibenzaldimino N-vinyl carbazole) Pd(II) complex has been synthesized and characterized by physicochemical and spectroscopic techniques. The complex was found to be highly active toward hydrogenation reactions of various organic substrates under atmospheric pressure at ambient temperature. A tentative reaction mechanism is proposed on the basis of kinetic studies and isolation of reactive intermediates. The catalyst shows good conversion rates, thermal stability and recyclability.