A regioselective 1,3‐dipolar cycloaddition of 2‐arylidene‐1‐tetralones with DPNI

Synthesis of a series of novel 1,3‐diphe nyl‐4‐arylspiropyrazolines[5.2¹]‐1¹‐tetralones has been accomplished in good yield by regioselective 1,3‐dipolar cycloaddition of diphenylnitrilimine with (E)‐2‐arylidene‐1‐tetralones. X‐ray crystal structure analysis of one of the products 4b confirms the structure and the regiochemistry of cycloaddition. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 331–336, 1999     

Synthesis of acridinedione derivatives as laser dyes

Synthesis of 9-alkyl, 10-alkyl, 9,10-dialkyl, and 10-aryl-3,4,6,7,9,10-hexahydro-1,8(2H,5H)acridinedione (2a–r) are described as a new class of laser dyes. Reactions of diamines with methylene bis(cyclohexane-1,3-dione) yielded the respective bisacridinediones (3a–e). These dyes lase around 478–494 nm and are compared with the standard dye coumarin-102. © 1996 John Wiley & Sons, Inc.     

Time-delayed chameleon: Analysis,synchronization and FPGA implementation

In this paper we report a time-delayed chameleon-like chaotic system which can belong to different families of chaotic attractors depending on the choices of parameters. Such a characteristic of self-excited and hidden chaotic flows in a simple 3D system with time delay has not been reported earlier. Dynamic analysis of the proposed time-delayed systems are analysed in time-delay space and parameter space. A novel adaptive modified functional projective lag synchronization algorithm is derived for synchronizing identical time-delayed chameleon systems with uncertain parameters. The proposed time-delayed systems and the synchronization algorithm with controllers and parameter estimates are then implemented in FPGA using hardware–software co-simulation and the results are presented.     

Simple synthesis and spectroscopic studies on cobalt added ZnO nanocrystals

Cobalt doped zinc oxide nanoparticles were prepared through simple wet chemical method. X-ray diffraction studies confirm the prepared particles are in wurtzite structure. Scanning Electron Microscopy studies show the shape and morphology of the particles. To identify the presence of cobalt in ZnO, Energy Dispersive X-ray analysis was done. Optical absorption measurements show the presence of exciton peak at 375 nm. Photoluminescence studies were done with the excitation wavelength of 330 nm, which shows the emission because of exciton recombination and oxygen vacancy.     

Existence of solutions for impulsive neutral functional differential equations with nonlocal conditions

The existence, uniqueness and continuous dependence of a mild solution of an impulsive neutral functional differential evolution nonlocal Cauchy problem in general Banach spaces are studied, by using the fixed point technique and semigroup of operators.     

Proton-conducting I-Carrageenan-based biopolymer electrolyte for fuel cell application

The essential part of electrochemical devices, such as fuel cells and batteries, is the polymer electrolyte with good mechanical, thermal, and chemical stability. The search for a new proton-conducting membrane with easy processability, non-toxic, and low-cost has been growing rapidly. The bio-based polymer electrolytes are now receiving much attention due to the green environment. Among the commercially available biopolymers, iota-Carrageenan (I-Carrageenan) is one of the biopolymer with good film-forming nature and with good mechanical stability. I-Carrageenan-based biopolymer membranes doped with ammonium bromide (NH₄Br) have been prepared using solution-casting technique, and distilled water is used as a solvent. The prepared I-Carrageenan-based biopolymer membranes have been characterized using FTIR, XRD, and AC impedance techniques. The complexation between the polymer and salt has been revealed by FTIR. The increase in the amorphous nature of the film due to the addition of salt has been confirmed by XRD. From AC impedance technique, the conductivity of pure I-Carrageenan has been found to be 1.46 × 10⁻⁵ S/cm. The addition of different wt% of NH₄Br increases the conductivity and reaches the highest value of 1.08 × 10⁻³ S/cm for 20% NH₄Br, and the conductivity decreases on further addition of NH₄Br due to the formation of ion aggregates.

     

Lithium ion-conducting polymer electrolytes based on PVA–PAN doped with lithium triflate

Ionics - Blend polymer electrolytes with optimized composition (92.5 PVA:7.5 PAN) doped with lithium triflate (LiCF3SO3) have been prepared in different concentrations by solution casting...     

Carbon-supported Pd-Co as cathode catalyst for APEMFCs and validation by DFT

Carbon supported PdCo catalysts in varying atomic ratios of Pd to Co, namely 1 : 1, 2 : 1 and 3 : 1, were prepared. The oxygen reduction reaction (ORR) was studied on commercial carbon-supported Pd and carbon-supported PdCo nanocatalysts in aqueous 0.1 M KOH solution with and without methanol. The structure, dispersion, electrochemical characterization and surface area of PdCo/C were determined by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM) and Cyclic Voltammetry (CV), respectively. The electrochemical activity for ORR was evaluated from Linear Sweep Voltammograms (LSV) obtained using a rotating ring disk electrode. The catalysts were evaluated for their electrocatalytic activity towards oxygen reduction reaction (ORR) in Alkaline Polymer Electrolyte Membrane Fuel Cells (APEMFCs). PdCo(3 : 1)/C gives higher performance (85 mW cm(-2)) than PdCo(1 : 1)/C, PdCo(2 : 1)/C and Pd/C. The maximum electrocatalytic activity for ORR in the presence of methanol was observed for PdCo(3 : 1)/C. First principles calculations within the framework of density functional theory were performed to understand the origin of its catalytic activity based on the energy of adsorption of an O(2) molecule on the cluster, structural variation and charge transfer mechanism.