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.     

Origins of the stability of imidazole-imidazole, benzene-imidazole, and benzene-indole dimers: CCSD(T)/CBS and SAPT calculations

The respective structures and stabilities of imidazole-imidazole, benzene-imidazole, and benzene-indole dimers have been investigated using different DFT-D functional, MP2, CCSD(T), and SAPT levels of theory with a medium basis set. Comparative analysis of binding energies and structural parameters of the dimers points to a preference for stacking contact or hydrogen bond in an imidazole-imidazole dimer. In contrast, a T-shaped configuration with H-π interaction is maximally advantageous for benzene-imidazole and benzene-indole dimers. High-level ab initio calculations at the CCSD(T)/CBS and DFT-SAPT levels show that classical hydrogen-bonded tilted imidazole-imidazole dimer is a global minimum structure and that it has high electrostatic energy. However, for benzene-imidazole and benzene-indole dimers, the global minimum (N-H···π) structure has high electrostatic energy as well as dispersion energy.     

Synthesis,spectroscopic characterization and antibacterial activity of lanthanide–tetracycline complexes

A series of Ln^III–tetracycline complexes of the type [Ln(TC)Cl₃]·2H₂O [Ln = lanthanum, praseodymium, neodymium, samarium, gadolinium, terbium, dysprosium and yttrium; TC = tetracycline] have been synthesized and characterized by analytical, i.r., electronic, ¹H-n.m.r. spectral studies, X-ray diffraction and thermogravimetric analysis. A pentagonal bipyramidal structure has been tentatively proposed for the new complexes. The ligand and the new complexes were tested in vitro to evaluate their activity against the bacteria Escherichia coli and Staphylococcus aureus.     

Influence of contact resistance and natural convection effects on non-dimensional effective thermal conductivity estimation of two-phase materials

In this article, the development of geometry dependent resistance model by considering contact resistance and natural convection effects are used to estimate the effective thermal conductivity of two-phase materials based on the unit cell approach. The algebraic equations have been derived based on isotherm approach for 2-D and 3-D spatially periodic medium. Comparison study has been made between developed models and experimental data. The result agrees well with experimental values.     

Hardness determination of bio-ceramics using Laser-Induced Breakdown Spectroscopy

Laser-Induced Breakdown Spectroscopy (LIBS) was applied to the analysis of bio-ceramic samples. The relationship between sample hardness and LIBS plasma properties was investigated, with comparison to conventional Vickers hardness measurements. The plasma excitation temperature T_e was determined using the line-to-continuum ratio for the Si (I) 288.16 nm emission line; we have demonstrated a linear relationship between sample surface hardness and plasma temperature. Results indicate that hardness determination based on measurements of T_e offers greater reproducibility than Vickers hardness measurements, under the conditions considered here. The validity of spectroscopic diagnostics based on LTE was confirmed.