Structural and magnetic property of Mn:ZnO bulk ceramic doped with rare earth (Gd/Sm) atoms

This paper reports the paramagnetic behavior of Mn doped ZnO co-doped with rare earth (Gd and Sm) atoms. The formation of secondary rare earth oxides (Gd₂O₃ and Sm₂O₃) is confirmed from the X-ray diffraction patterns. The rare earth oxides in the system forbids the grain growth and interconnection between the grains. The weak link between the grains suppresses the long range exchange interaction between the Mn ions and hence, reduces the ferromagnetic ordering. Owing to the large mismatch between ionic radii of rare earth and transition metal atoms inside the matrix, the rare earth element cannot contribute to promote ferromagnetic behavior in Mn doped ZnO, irrespective of their high individual magnetic moments.     

Evidence of the Fano resonance in a temperature dependent Raman study of CaCu3Ti4O12 and SrCu3Ti4O12

Phononic excitations have been investigated using Raman scattering studies on CaCu(3)Ti(4)O(12) and SrCu(3)Ti(4)O(12) compounds as a function of temperature down to 10 K. Evidence of the Fano resonance effect is found in the A(g)(1) mode with an asymmetric phonon line shape that occurs because of composite electron-phonon scattering due to the onset of metallic fractions in the system. The evolution of the Fano line shape with temperature affirms the existence of nanoscale phase separation and the prominence of orbitally disrupted metallic regions above 100 K. Anomalies in the evolution of the line width of the A(g)(1) Raman mode with temperature are observed around 100 K where these compounds show an orbital order/disorder transition. These anomalies manifest mutual coupling of orbital degrees of freedom to lattice degrees of freedom.     

Erratum to: Axial Imidazole Binding Strengths in Porphyrinoid Cobalt(III) Complexes as Studied by Tandem Mass Spectrometry

The Co(II) complexes of twelve meso-tetraaryl-porphyrins, -chlorins, and chlorin analogues containing non-pyrrolic heterocycles were synthesized and converted in situ to the corresponding Co(III) complexes coordinated to one or two imidazoles. Electrospray ionization tandem mass spectrometry (ESI-MS/MS) in conjunction with the energy-variable collision-induced dissociation (CID) technique was used to compare the relative gas-phase binding strength of the axially coordinated imidazoles to the octahedral and square planar Co(III) porphyrinoid complex ions. The observed binding energies of these ligands were rationalized in terms of the effects of porphyrinoid core structure and meso-substitution on the electron density on the central Co(III) centers. Some of these trends were supported by DFT-based computational studies. The study highlights to which extend porphyrins vary from chlorins and chlorin analogues in their coordination abilities and to which extraordinary degree meso-thienyl-substituents influence the electronic structure of porphyrins. The study also defines further the scope and limits CID experiments can be used to interrogate the electronic structures of metalloporphyrin complexes.     

Protonation and oligomerization of gaseous isoprene on mildly acidic surfaces: implications for atmospheric chemistry

In a global process linking the Earth's climate with its ecosystems, massive photosynthetic isoprene (ISOP) emissions are converted to light-scattering haze. This phenomenon is imperfectly captured by atmospheric chemistry models: predicted ISOP emissions atop forest canopies would deplete the oxidizing capacity of the overhead atmosphere, at variance with field observations. Here we address this key issue in novel laboratory experiments where we apply electrospray mass spectrometry to detect online the products of the reactive uptake of gaseous ISOP on the surface of aqueous jets as a function of acidity. We found that ISOP is already protonated to ISOPH(+) and undergoes cationic oligomerization to (ISOP)(2)H(+) and (ISOP)(3)H(+) on the surface of pH < 4 water jets. We estimate uptake coefficients, γ(ISOP) = (0.5 - 2.0) × 10(-6) on pH = 3 water, which translate into the significant reuptake of leaf-level ISOP emissions in typical (surface-to-volume ～5 m(-1)) forests during realistic (a few minutes) in-canopy residence times. Our findings may also account for the rapid decay of ISOP in forests after sunset and help bring the global budget of volatile organic compounds closer to balance.     

Analysis of transport of collimated radiation in a participating media using the lattice Boltzmann method

Application of the lattice Boltzmann method (LBM) recently proposed by Asinari et al. [Asinari P, Mishra SC, Borchiellini R. A lattice Boltzmann formulation to the analysis of radiative heat transfer problems in a participating medium. Numer Heat Transfer B 2010; 57:126–146] is extended to the analysis of transport of collimated radiation in a planar participating medium. To deal with azimuthally symmetric radiation in planar medium, a new lattice structure for the LBM is used. The transport of the collimated component in the medium is analysed by two different, viz., flux splitting and direct approaches. For different angles of incidence of the collimated radiation, the LBM formulation is tested for the effects of the extinction coefficient, the anisotropy factor, and the boundary emissivities on heat flux and emissive power distributions. Results are compared with the benchmark results obtained using the finite volume method. Both the approaches in LBM provide accurate results.     

Axially Symmetric Cosmological Model with Wet Dark Fluid in Bimetric Theory of Gravitation

The purpose of this paper is to investigate the role of wet dark fluid in axially symmetric cosmological model within the frame work of bimetric theory of gravitation proposed by Rosen (Gen. Relativ. Gravit. 4:435, 1973). In this theory, it is observed that there is no contribution from wet dark fluid.     

Phonon dispersion of graphene revisited

The phonon dispersion of graphene is derived by using a simple mass spring model and considering up to the first, second, third, and fourth nearest-neighbor interactions. The results obtained from different nearest-neighbor interactions are compared and it is shown that the k ² dependence for the out-of-plane transverse acoustic mode obtained in other sophisticated methods as well as experiment occurs only after including the fourth nearest-neighbor interaction.     

Domain growth and ordering kinetics in dense quark matter

The kinetics of chiral transitions in quark matter is studied in a two-flavor Nambu-Jona-Lasinio model. We focus on the phase-ordering dynamics subsequent to a temperature quench from the massless quark phase to the massive quark phase. We study the dynamics by considering a phenomenological model (Ginzburg-Landau free-energy functional). The morphology of the ordering system is characterized by the scaling of the order-parameter correlation function.     

Cu(II)‐catalyzed oxidation of thiols by superoxide ligated to CoIII2

Copper(II) dramatically catalyzes the oxidation of thiols by a superoxide bridging two Co^III ions. The catalyzed path overwhelmingly dominates over the uncatalysed path and is first order in the superoxo complex concentration. The first‐order rate constants show a first‐order dependence in [Cu²⁺], a second‐order dependence in [thiol] and linearly varies with [H⁺]^?3. On the basis of observed kinetics reported here, it is proposed that Cu(II) reacts with two thiol molecules to form a Cu^II(thiol)₂ complex, an electron is transferred from one ligated thiol to the Cu^II center to form Cu^I(thiol) and a thiyl radical. The copper(I)‐thiol complex is oxidized by the conjugate base of the title complex to regenerate Cu^II(thiol). A Cu^II/I catalytic cycle is thus believed to be responsible for the observed catalysis. Copyright © 2012 John Wiley & Sons, Ltd.     

ENO Reconstruction and ENO Interpolation Are Stable

We prove that the ENO reconstruction and ENO interpolation procedures are stable in the sense that the jump of the reconstructed ENO point values at each cell interface has the same sign as the jump of the underlying cell averages across that interface. Moreover, we prove that the size of these jumps after reconstruction relative to the jump of the underlying cell averages is bounded. Similar sign properties and the boundedness of the jumps hold for the ENO interpolation procedure. These estimates, which are shown to hold for ENO reconstruction and interpolation of arbitrary order of accuracy and on nonuniform meshes, indicate a remarkable rigidity of the piecewise polynomial ENO procedure.