Studies on electrophoretically deposited nanostructured barium titanate systems and carrier transport phenomena

We report on the development of nanostructured barium titanate (BaTiO₃, BT) films on ~200-μm-thick Ag substrates by employing a cathodic electrophoretic deposition (EPD) technique, where solid-state-derived BT nanoparticles are used as the starting material. Structural, morphological and compositional analyses of the as-synthesized BT nanoparticles and films were performed by X-ray diffraction, electron microscopy and energy-dispersive spectroscopy studies. The synthesized nano-BT system has an average crystallite size of ~8.1 nm and a tetragonality (c/a) value ~1.003. To reveal current transport mechanism, the BT films possessing microporous structures and surrounded by homogeneously grown islands were assessed in a metal–insulator–metal (MIM) conformation. The forward current conduction was observed to be purely thermionic up to respective voltages of ~1.4 and 2.2 V as for the fresh and 3-day aged samples. On the other hand, direct tunneling (DT)-mediated Ohmic feature was witnessed at a comparatively higher voltage, beyond which Fowler–Nordheim tunneling (FN) dominates in the respective MIM junctions. The magnitude of current accompanied by FN process was observed to be stronger in reverse biasing than that of forward biasing case. The use of microporous BT films can offer new insights as regards regulated tunneling events meant for miniaturized nanoelectronic elements/components.     

Exploring a hidden fermionic dark sector

In this paper, we present a generalized unified method for finding multiwave solutions of the time-fractional (2+1)-dimensional Nizhnik–Novikov–Veselov equations. The fractional derivatives are described in the modified Riemann–Liouville sense. The fractional complex transform has been suggested to convert fractional-order differential equations with modified Riemann–Liouville derivatives into integer-order differential equations, and the reduced equations can be solved by symbolic computation. Multiauxiliary equations have been introduced in this method to obtain not only multisoliton solutions but also multiperiodic or multielliptic solutions. It is shown that the considered method is very effective and convenient for solving wide classes of nonlinear partial differential equations of fractional order.     

A facile microwave assisted synthesis of spiro-1,3-oxazines from N-(2-(cyclohex-1-en-1-yl)ethyl)amides

A mild and efficient methodology has been developed for the synthesis of spiro-1,3-oxazine derivatives by the microwave assisted cyclization of N-2-(1′-cyclohexenyl)ethyl-acetamides/benzamides. The reaction was catalyzed by in situ generated trimethylsilyl iodide and featured by its very short reaction time. The starting materials were easily obtained by the condensation of substituted acetic/benzoic acids with 2-(1′-cyclohexenyl)ethyl amine.     

Probing the Binding of Syzygium-Derived α-Glucosidase Inhibitors with N- and C-Terminal Human Maltase Glucoamylase by Docking and Molecular Dynamics Simulation

Human maltase glucoamylase (MGAM) is a potent molecular target for controlling post prandial glucose surplus in type 2 diabetes. Binding of small molecules from Syzygium sp. with α-glucosidase inhibitory potential in MGAM has been investigated in silico. Our results suggest that myricetin was the most potent inhibitor with high binding affinity for both N- and C-terminals of MGAM. Molecular dynamics revealed that myricetin interacts in its stretched conformation through water-mediated interactions with C-terminal of MGAM and by normal hydrogen bonding with the N-terminal. W1369 of the extended 21 amino acid residue helical loop of C-terminal plays a major role in myricetin binding. Owing to its additional sugar sites, overall binding of small molecules favours C-terminal MGAM.     

Direct Hydrogenation of Nitroaromatics at Room Temperature Catalyzed by Magnetically Recoverable Cu@Fe2O3 Nanoparticles

Metal embedded in metal oxide nanoparticles are active as catalyst in plethora of industrially important reactions. Herein, embedded Cu@Fe₂O₃ nanoparticles was synthesized via a one step hydrothermal strategy which selectively catalyzes the hydrogenation of diverse nitroaromatics in H₂O at room temperature. The remarkable catalytic performance is due to the successful hybridization of metallic Cu and Fe₂O₃ which in turn allows easy electroflipping between various oxidation states of Cu and Fe. Azo- and azoxy-compounds are not formed during the catalyzed process. This evidently establish that the hydrogenation of nitroaromatics proceeds via direct route with >99% selectivity to the corresponding anilines.     

Holographic Dark Energy in Higher Derivative Gravity with Varying Gravitational Constant

In this paper we investigate the holographic dark energy scenario in higher derivative gravity with a varying gravitational constant. We introduce a kind of energy density from higher derivative gravity which has role of the same as holographic dark energy. We obtain the exact differential equation , which determine the evolution of the dark energy density based on varying gravitational constant G. We also find out a cosmological application of our work by evaluating a relation for the equation of state of dark energy for low redshifts containing varying G correction.     

Deviations from tri-bimaximal neutrino mixing using type II seesaw

We study the possibility of generating deviations from tri-bimaximal (TBM) neutrino mixing to explain the non-zero reactor mixing angle within the framework of both type I and type II seesaw mechanisms. The type I seesaw term gives rise to the μ–τ   symmetric TBM pattern of neutrino mass matrix as predicted by generic flavor symmetry models like _A4$A_4$ whereas the type II seesaw term gives rise to the required deviations from TBM pattern to explain the non-zero _θ13${\theta }_{13}$. Considering extremal values of Majorana CP phases such that the neutrino mass eigenvalues have the structure (_m1,−_m2,_m3)$(m_1,-m_2,m_3)$ and (_m1,_m2,_m3)$(m_1,m_2,m_3)$, we numerically fit the type I seesaw term by taking oscillation as well as cosmology data and then compute the predictions for neutrino parameters after the type II seesaw term is introduced. We consider a minimal structure of the type II seesaw term and check whether the predictions for neutrino parameters lie in the 3σ range. We also outline two possible flavor symmetry models to justify the minimal structure of the type II seesaw term considered in the analysis.     

Conducting polymer based hybrid structure as transparent and flexible field electron emitter

An efficient cathode material with high transparency (93%) based on conducting polymer poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and single wall carbon nanotubes (SWCNTs) has been developed for the fabrication of highly transparent and flexible field electron emitters (FEE). This kind of material showed superior field emission (FE) performance with very high current density (10^–3A/cm²) at very low electric field. The FE performance of the hybrid materials was dramatically improved compared to either SWCNTs and PEDOT:PSS. Thus the hybrid structures of conducting polymer and SWCNTs might be a good choice for use as a cathode material to enhance the FE performance and for potential application in future portable displays. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Target-Directed Azide-Alkyne Cycloaddition for Assembling HIV-1 TAR RNA Binding Ligands

The highly conserved HIV-1 transactivation response element (TAR) binds to the trans-activator protein Tat and facilitates viral replication in its latent state. The inhibition of Tat–TAR interactions by selectively targeting TAR RNA has been used as a strategy to develop potent antiviral agents. Therefore, HIV-1 TAR RNA represents a paradigmatic system for therapeutic intervention. Herein, we have employed biotin-tagged TAR RNA to assemble its own ligands from a pool of reactive azide and alkyne building blocks. To identify the binding sites and selectivity of the ligands, the in situ cycloaddition has been further performed using control nucleotide (TAR DNA and TAR RNA without bulge) templates. The hit triazole-linked thiazole peptidomimetic products have been isolated from the biotin-tagged target templates using streptavidin beads. The major triazole lead generated by the TAR RNA presumably binds in the bulge region, shows specificity for TAR RNA over TAR DNA, and inhibits Tat–TAR interactions.     

Cu‐Based Nanoparticles as Emerging Environmental Catalysts

This account provides an overview of current research activities on nanoparticles containing the earth‐abundant and inexpensive element copper (Cu) and Cu‐based nanoparticles, especially in the field of environmental catalysis. The different synthetic strategies with possible modification of the chemical/ physical properties of these nanoparticles using such strategies and/or conditions to improve catalytic activity are presented. The design and development of support and/or bimetallic systems (e. g., alloys, intermetallic, etc.) are also included. Herein, we report synthetic approaches of Cu and Cu‐based nanoparticles (monometallic copper, bimetallic copper and copper (II) oxide nanoparticles/nanostructures) and impregnation of such nanoparticles onto support material (e. g., Co₃O₄ nanostructure), along with their applications as environmental catalyst for various oxidation and reduction reactions. Finally, this account provides necessary advances and perspectives of Cu‐based nanoparticles in the environmental catalysis.