Studies on optical and dielectric properties of Al2O 3 thin films prepared by electron beam evaporation and spray pyrolysis method

Al2O3 thin films find a number of applications in optoelectronics, sensors and tribology. In this paper, we report the preparation and characterization of alumina films prepared by both electron beam evaporation and spray pyrolysis method. The electrical properties of alumina films were determined by measuring (C-V) and (I-V) characteristics in a metal oxide semiconductor (MOS) structure. A relative dielectric constant (εr) of 9.6 for spray pyrolysed films and 8.3 for evaporated films was obtained. The breakdown electric field was found to be around 5 and 1MV/cm, respectively for spray pyrolysed and evaporated films. The refractive index of alumina films by evaporation was found to be 1.71 and 1.61 at 275 and 500 nm, respectively. The optical band gap of spray pyrolysed films deposited at 300 °C was found to be in the range of 5.40-5.55 eV. Structural, elemental analysis and stoichiometry of the films was studied by scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX), Auger electron spectroscopy (AES) and Rutherford back scattering (RBS) spectra. © 2003 Elsevier B.V. All rights reserved

Synthesis, characterization, antibacterial, antifungal and anthelmintic activities of a new 5-​nitroisatin Schiff base and its metal complexes

The copper (II)​, cobalt (II)​, nickel (II) and zinc (II) complexes of 5 - nitroisatin Schiff base (L) (L = Schiff base derived from 5-​nitroisatin and 2-​methyl-​4-​nitroaniline) were synthesized and characterized. The authenticity of the ligand and its metal complexes has been established by micro anal., IR, NMR, LC​/MS, UV-​VIS and elec. conductance measurements. The ligand acts as a bidentate agent in which the carbonyl oxygen and the azomethine nitrogen of 5-​nitroisatin are involved in co-​ordination. Square planar geometry was proposed for the Cu (II) and Ni (II) complexes and tetrahedral geometry was proposed for the Co (II) and Zn (II) complexes. The ligand and its metal complexes have been screened for antibacterial activity against Staphylococcus aureus, Escherichia coli, etc. and for antifungal activity against Aspergillus niger, Aspergillus flavous, etc. The Schiff base and its complexes were also screened for anthelmintic activity on earthworms. Both samples displayed significant activitie

Variational approach to self-adjointness and some applications to biomathematics

AbstractIn this paper using variational approach, we obtain necessary and sufficient conditions for a nonlinear boundary value problem to be self-adjoint. Analytic representations of Lagrangian and Hamiltonian are given. Several interesting applications to biological models are also discussed

Synthesis, Characterization and Biological Activities of a New 5-Chloroisatin Schiff Base and its Metal Complexes

Copper(II), cobalt(II), nickel(II) and zinc(II) complexes of 5-chloroisatin Schiff base (L) (L= Schiff base derived from 5-chloroisatin and 2-methyl-4- nitro aniline) were synthesized and characterized. The authenticity of the ligand and its metal complexes had been established by micro analysis, IR, NMR, LC/MS, UV-Vis and electrical conductance measurements. The ligand acts as a bidentate in which the carbonyl oxygen and the azomethine nitrogen of 5-chloroisatin are involved in co-ordination. Square planar geometry was proposed for Cu(II) and Ni(II) complexes and tetrahedral geometry was proposed for Co(II) and Zn(II) complexes. The ligand and its metal complexes have been screened for their antibacterial activity against bacterias viz. Staphylococcus aureus and Escherichia coli etc. and antifungal activity against fungi Aspergillus niger and Aspergillus flavous etc. The activities of both the samples have shown significant and noticeable changes on complexations