High pressure synthesis of late rare earth RFeAs(O,F) superconductors; R = Tb and Dy

New TbFeAs(O,F) and DyFeAs(O,F) superconductors with critical temperatures T(c) = 46 and 45 K and very high critical fields, >/=100 T, have been prepared at 1100-1150 degrees C and 10-12 GPa, demonstrating that high pressure may be used to synthesise late rare earth derivatives of the recently reported RFeAs(O,F) (R = La-Nd, Sm, Gd) high temperature superconductors.     

Chitosan–sodium alginate encapsulated Co-doped ZrO<Subscript>2</Subscript>–MWCNTs nanocomposites for photocatalytic decolorization of organic dyes

Photocatalytic decolorization properties of cobalt doped-ZrO₂-multiwalled carbon nanotubes (Co–ZrO₂–MWCNTs) and chitosan–sodium alginate encapsulated Co–ZrO₂–MWCNTs (CS/Alg–Co–ZrO₂–MWCNTs) with varying weight percentage of Co–ZrO₂–MWCNTs are presented in this research paper. The Co–ZrO₂–MWCNTs was first synthesized through homogenous co-precipitation method and introduced into the chitosan–sodium sodium alginate (CS/Alg) biopolymer matrix. The bio-nanocomposites were characterized using X-ray powder diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, (UV–Vis)-spectroscopy and energy dispersive spectroscopy to obtain information on their structure, formation, morphology, size and elemental analysis. The photodecolorization efficiency of the samples was determined through their decolorization of trypan blue dye aqueous solution in 180 min. Recyclability of the catalysts was also assessed. The bio-nanocomposites experienced reduced band gap values with subsequent improvement in visible light activity compared to the uncapped Co–ZrO₂–MWCNTs. All the CS/Alg–Co–ZrO₂–MWCNTs exhibited higher photodecolorization activities than the uncapped Co–ZrO₂–MWCNTs. The most efficient catalyst (CS/Alg–40 % Co–ZrO₂–MWCNTs) with a band gap of 2.56 eV displayed 94 % decolorization efficiency of the dye. Though reusability of the catalyst is significant, its efficiency diminished consistently after each cycle.     

Rapid and accurate measurement of transverse relaxation times using a single shot multi-echo echo-planar imaging sequence

Methods for making rapid and accurate measurements and maps of the transverse relaxation time from a single free induction decay (FID) are proposed. The methods use a multi-echo sequence in combination with B1 insensitive (hyperbolic secant or BIREF2b) refocusing pulses and rapid echo-planar imaging techniques. The results were calibrated against a single spin echo echo-planar imaging sequence using a phantom containing a range of CuSO4 concentrations. The mean percentage absolute difference between the multi-echo and single-echo results was 3% for the multi-echo sequence using the hyperbolic secant refocusing pulse, and 7% for the multi-echo sequence using the BIREF2b refocusing pulse, compared to 13% for a multi-echo sequence using a nonselective sinc refocusing pulse. The use of the sequences in vivo has been demonstrated in studies of gastric function, i.e., the measurement of gastric dilution and monitoring of formation of a raft of alginate polysaccharide within the stomach.     

Perron's method for second order hyperbolic PDE. Part III

We continue Part I of this paper. Here, in Part III, comparison principles are proved for nonsmooth sub and super solutions (with nonsmooth Cauchy data) of semilinear hyperbolic PDE in compact regular domains of R⁺×R⁺ when n?3, and existence of a nonsmooth solution to the nonsmooth Cauchy problem is proved by a Perron-like method.     

Utility of neodymium diiodide as a reductant in ketone coupling reactions

[reaction: see text] The viability of NdI(2) as a one-electron reducing agent in organic synthesis has been examined by studying coupling reactions between alkyl chlorides and ketones and aldehydes.     

Numerical Approximation of Time Domain Electromagnetic Scattering from a Thin Wire

We present two new stable schemes for computing the current induced on the surface of a thin wire by an incident time-dependent electromagnetic field. The problem involves solving a retarded potential integral equation (RPIE). One algorithm solves the previously studied reduced kernel RPIE problem, and the other solves the more complicated exact kernel RPIE problem (for which there are no previous numerical results). Both algorithms behave stably for arbitrarily chosen values of the mesh size. Test experiments and numerically computed values of the induced current are presented.