Vibrational spectroscopy analysis of ion conduction mechanism in dispersed phase polymer nanocomposites

A novel combination of dispersed phase polymer nanocomposite electrolyte based on PEO₈‐LiClO₄+ x wt % nano‐CeO₂ has been investigated. A model for ion transport mechanism has been proposed to account for substantial enhancement of its electrical conductivity by ～ 2 orders of magnitude at low volume fraction of the filler reinforcement in the polymer nanocomposite films. The strength of the proposed model is based on unambiguous evidences from FTIR, TEM, and conductivity analysis. The FTIR results provide clear role of nanofiller concentration on ion–ion interaction quantified in terms of the fraction of free anion and ion‐pairs present in the nanocomposite films and its excellent correlation with conductivity versus filler concentration. The presence of asymmetry in the ν₄(ClO₄^?) band observed at 625 cm^?1 is attributed to its resolved degeneracy suggesting the presence of both uncoordinated and cation‐coordinated ClO₄^? anion in the matrix due to ion–ion and ion–filler interactions assisted by Lewis acid–base interaction. The enhancement in conductivity at low concentration is possibly due to direct interaction of nano‐CeO₂ with both polymer host and anions resulting in the release of ionic charges. Drastic conductivity reduction at higher concentration is related to charge immobilization because of ion/ion‐pair entrapment by local clusters of filler as evidenced in TEM. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 60–71, 2009     

Approximation by Durrmeyer–Bezier operators

In the present paper, we consider the Bezier variant M_n,α(f,x) of the generalized Durrmeyer type operators, and obtain an estimate on the rate of convergence of M_n,α(f,x) for the decomposition technique of functions of bounded variation. In the end we propose an open problem for the readers and give an asymptotic formula for these generalized Durrmeyer type operators.     

Experiments on the reflection of cold atoms from magnetic thin films

We report the results from a series of experiments in which ferromagnetic thin films were used as atom mirrors for laser-cooled rubidium atoms released from a magneto-optical trap. The thin films were made of cobalt and lanthanum calcium manganite (LCMO) with thicknesses between 20 and 300 nm. The magnetic domains in these thin films have a periodic structure where the spatial period is of the order of the thickness of the film, and the field decays exponentially above the film over a length scale comparable to the domain size. Thus, the neutral atoms reflect off these films from distances comparable to the thickness of the film, resulting in modification of the reflectivity due to the competition between the repulsive magnetic force and the attractive short-range forces such as van der Waals and Casimir forces. The smoothness of the atom mirror is also modified due to the proximity of the magnetic domains. The reflectivity is sensitive to the domain structure and size, which can be modified in LCMO by applying a modest external magnetic field. In this paper, we discuss the evaluation of the thin films as magnetic mirrors for atom optics, and the measurement of the van der Waals force with an accuracy of about 15%, using cobalt thin films. We also discuss some preliminary results on the temperature-dependent reflectivity for atoms near the ferromagnetic transition at 250 K in the LCMO film, and on the domain dynamics and relaxation.     

Effect of a small disruption of the Ca site on the geometrically frustrated magnetic behavior of Ca3CoRhO6

The compound, Ca₃CoRhO₆, containing magnetic Co-Rh chains intervened by Ca ions, has been known to be one of the few exhibiting ‘partially disordered antiferromagnetic structure (PDA)’ due to geometrical frustration. Here, we report the influence of partial replacement of Ca by Y on the magnetic anomalies by investigating the solid solution, Ca_3−xY _xCoRhO₆, by bulk measurements. There are profound changes in the magnetic behavior, the most notable one being that the features attributable to spin-chain magnetism and PDA structure get suppressed dramatically by a small replacement of Ca by Y (x<0.3), despite the fact that the magnetic chain is not disrupted. This finding suggests that this compound is on the verge of PDA-structural-instability.     

Suppressing proton decay in the minimal SO(10) model

We show that in a class of minimal supersymmetric SO(10) models which have been found to be quite successful in predicting neutrino mixings, all proton decay modes can be suppressed by a particular choice of Yukawa textures. The required texture not only fits all lepton and quark masses as well as Cabibbo-Kobayashi-Maskawa parameters, but it also predicts neutrino mixing parameter U(e3) and Dirac CP phase sin(/delta(MNS)/ to be 0.07-0.09 and 0.3-0.7, respectively.     

Cabibbo angle,CP violation and quark masses

By adding suitable discrete flavor symmetries to SU(2)_L ? SU(2)_R ? U(1) left-right symmetric gauge models of weak and electromagnetic interactions, we are able to express all the mixing angles between the quark flavors (u, d, s,c) in terms of the quark masses. This enables us to compute the Cabibbo angle and the CP violating phases using plausible values for the quark masses. The CP violating K ar 2π decay amplitude η_+? (and η₀₀ in the model is then given purely in terms of the parity violating parameter of the model (m_WL⁺/m_WR⁺)².     

Coefficient Inequalities for p-Valent Functions

In the present paper, the authors introduce a new subclass of p-valent analytic functions with complex order defined on the open unit disk U={z:z∈C and |z|1} and obtain coefficient inequalities for the functions in these class. Application of these results for the functions defined by the convolution are also obtained.