Nonlinear Dispersive and Dissipative Electrostatic Structures in Two-Dimensional Electron-Positron-Ion Quantum Plasma

The nonlinear features of two-dimensional ion acoustic(IA) solitary and shock structures in a dissipative electron-positron-ion(EPI) quantum plasma are investigated. The dissipation in the system is taken into account by incorporating the kinematic viscosity of ions in plasmas. A quantum hydrodynamic(QHD) model is used to describe the quantum plasma system. The propagation of small but finite amplitude solitons and shocks is governed by the Kadomtsev-Petviashvili-Burger(KPB) equation. It is observed that depending on the values of plasma parameters(viz.quantum diffraction, positron concentration, viscosity), both compressive and rarefactive solitons and shocks are found to exist. Furthermore, the energy of the soliton is computed and possible solutions of the KPB equation are presented numerically in terms of the monotonic and oscillatory shock profiles     

Structure and reaction dynamics of SHE Z = 130

This study investigates the structural properties of super-heavy nuclei with Z = 130 by adopting the relativistic mean-field(RMF) theory within an axially deformed oscillator basis with the NL3 force parameter set. We study the binding energies, quadrupole deformation, nuclear radii, neutron separation energies, and other bulk properties.Moreover, we analyze the favorable decay modes for clear cognitive content of nuclei, such as alpha decay, using different formulae including the Viola-Seaberg, analytical formula of Royer, universal curve formula, and universal decay law. We compare these with the corresponding fission process. The spontaneous fission of super-heavy nuclei is studied with Z = 130 within the mass region 310 ≤A≤340. The results exhibit good agreement with finite range droplet model(FRDM) data. This formalism presents a significant step forward in the study of the structure and decay modes of the isotopes of Z = 130. With this appraisal, we investigate the possible shell/sub-shell closure for super-heavy nuclei adjacent by decay chains of alpha and other radioactive decay particles.     

Microscopic theory of substrate-induced gap effect on real AFM susceptibility in graphene

In this article, the novel (G ^′/G)-expansion method is successfully applied to construct the abundant travelling wave solutions to the KdV–mKdV equation with the aid of symbolic computation. This equation is one of the most popular equation in soliton physics and appear in many practical scenarios like thermal pulse, wave propagation of bound particle, etc. The method is reliable and useful, and gives more general exact travelling wave solutions than the existing methods. The solutions obtained are in the form of hyperbolic, trigonometric and rational functions including solitary, singular and periodic solutions which have many potential applications in physical science and engineering. Many of these solutions are new and some have already been constructed. Additionally, the constraint conditions, for the existence of the solutions are also listed.     

Electronic structure and structural stability of LaAl2 and LaAl3—A comparative study

The large structural stability regime of LaAl₂ and LaAl₃ as a function of pressure is investigated by the band structure calculations using the FP-LAPW method. An earlier experimental study has revealed that there is no structural phase transition at ∼35 and ∼30 GPa for LaAl₂ and LaAl₃, respectively. Our calculations indicate that in the density of states curve of LaAl₂, the Fermi level (E_F) lies in a slope between bonding maxima and antibonding minima. At high pressures the E_F moves slightly towards the valley, but this shifting does not affect its structural stability. In LaAl₃, the E_F falls in a flat region in the density of states and does not move even up to 33 GPa. The band dispersion curves for both the compounds show movement of bands under the influence of pressure. Some of them cross the Fermi level leading to so called Lifshitz transitions. However, it is seen that these electronic changes do not manifest into any volume anomaly in LaAl₃ under pressure. Our study clearly shows that the density of states behavior for LaAl₂ and LaAl₃ satisfies the Yamashita-Asano criterion for structural stability. The theoretical equations of state, bulk modulus and its pressure derivative values are compared with the experimental values.     

Mordenite-incorporated PVA–PSSA membranes as electrolytes for DMFCs

Composite membranes with mordenite (MOR) incorporated in poly vinyl alcohol (PVA)–polystyrene sulfonic acid (PSSA) blend tailored with varying degree of sulfonation are reported. Such a membrane comprises a dispersed phase of mordenite and a continuous phase of the polymer that help tuning the flow of methanol and water across it. The membranes on prolonged testing in a direct methanol fuel cell (DMFC) exhibit mitigated methanol cross-over from anode to the cathode. The membranes have been tested for their sorption behaviour, ion-exchange capacity, electrochemical selectivity and mechanical strength as also characterized by Fourier transform infrared spectroscopy and thermogravimetric analysis. Water release kinetics has been measured by magnetic resonance imaging (NMR imaging) and is found to be in agreement with the sorption data. Similarly, methanol release kinetics studied by volume-localized NMR spectroscopy (point resolved spectroscopy, PRESS) clearly demonstrates that the dispersion of mordenite in PVA–PSSA retards the methanol release kinetics considerably. A peak power-density of 74 mW/cm² is achieved for the DMFC using a PVA–PSSA membrane electrolyte with 50% degree of sulfonation and 10 wt.% dispersed mordenite phase. A methanol cross-over current as low as 7.5 mA/cm² with 2 M methanol feed at the DMFC anode is observed while using the optimized composite membrane as electrolyte in the DMFC, which is about 60% and 46% lower than Nafion-117 and PVA–PSSA membranes, respectively, when tested under identical conditions.     

Thermal characterization of piezoelectric and non-piezoelectric Lead Meta-Niobate

Powerful tools like Differential Scanning Calorimetry (DSC) and DTA seem to be under-utilized for the emerging materials for high temperature piezoelectric sensors, while thermal aspects of such piezoelectric phase change are also of theoretical interest. Curie temperature of Lead Meta-Niobate (PbNb₂O₆ or PN) is 570 °C, much higher than that for widely used lead zirconate titanate, making PN potentially more attractive at high temperatures. However, the only specific heat measurement for PN appears to be the 2–25 K study by Lawless, leaving the Curie temperature region unexplored. For PN, piezoelectricity is possible for the meta-stable orthorhombic structure only. So, we prepared pure phase orthorhombic PN by quenching (Q) and the rhombohedral PN by slow-cooling (S). We report for the first time, to our knowledge, DSC across the Curie temperature for Q and S types of PN. We find clear and interesting DSC signals at the Curie temperature in heating and cooling graphs for quenched (Q) PbNb₂O₆ only and none for the slow-cooled (S) PbNb₂O₆.     

Synthesis of novel benzoxazocino quinoliniums and quinolones under PTC conditions and their application in Suzuki cross coupling reaction for the construction of polynuclear heteroaromatics

A general and highly efficient synthetic protocol under phase transfer catalytic condition has been established for the synthesis of fused tetracyclic oxazocinoquinolone analogues which served as the precursors for novel biaryl quinolones using microwave assisted Suzuki cross coupling reaction.     

Synthesis of novel chromogenic azocalix[4]arenemonoquinones and their binding with alkali metal cations

Five new chromogenic azocalix[4]arenemonoquinones have been synthesized, characterized and examined for their interaction with alkali metal cations (Li⁺, Na⁺, K⁺, Rb⁺ and Cs⁺) by UV-visible spectroscopic and cyclic voltammetric techniques. It has been determined that 4a selectively exhibits a significant bathochromic shift in its UV-visible spectrum on interaction with potassium ion in comparison to its treatment with other alkali metal cations. The binding stoichiometry of 4a and potassium ion was established to be 1:1 with an association constant of 3.27 × 10⁴ M^?1. Cyclic voltammetric experiments in 4:1 dichloromethane-acetonitrile also revealed a significant anodic shift (ΔE _(1/1′) = 115 mV) of the original redox waves of 4a on interaction with potassium ion.     

A Raman study of multiferroic LuMnO3

Magnetic and dielectric measurements confirm the multiferroic nature of LuMnO₃. Raman spectra of LuMnO₃ have been recorded in the 77–800 K range covering both the antiferromagnetic transition at 90 K and the ferroelectric–paraelectric transition at 750 K. The changes in the phonon modes frequencies and band-widths indicate the presence of phonon–spin coupling in the antiferromagnetically ordered phase. The ferroelectric–paraelectric transition is accompanied by the broadening and disappearance of many of the phonon modes. Some of the phonon modes also show anomalies at the ferroelectric transition.     

Asymptotically strict pseudocontractive mappings in the intermediate sense

It is proved that the modified Mann iteration process: _xn+1=(1−_αn)_xn+_αnTⁿ_xn,n∈N$x_{n+1}=(1-{\alpha }_n)x_n+{\alpha }_n{T}^n{x}_n,n\in \mathbb{N}$, where {_αn}$\left\{{\alpha }_n\right\}$ is a sequence in (0, 1) with δ≤_αn≤1−κ−δ$\delta \le {\alpha }_n\le 1-\kappa -\delta$ for some δ∈(0,1)$\delta \in (0,1)$, converges weakly to a fixed point of an asymptotically κ$\kappa$-strict pseudocontractive mapping T$T$ in the intermediate sense which is not necessarily Lipschitzian. We also develop CQ method for this modified Mann iteration process which generates a strongly convergent sequence.