Anita Rani

Synthesis and pharmacological evaluation of some quinoline derivatives as potential cognition enhancers.

The present paper describes the synthesis of a series of substituted 6-amino (1a-c) and 8-aminoquinoline derivatives (2b-c) and the evaluation of their ability to prevent the memory decline using a behavioural model, i.e. the elevated plus maze test. The effect of the candidate drugs on the activity of acetylcholinesterase was studied using the enzyme source from the mouse brain. The structures of the synthesized compounds were confirmed by UV, IR, 1H-NMR and elemental analysis. The 6-aminoquinoline derivative [6-(4-pyridyl)methylaminoquinoline] (1c) oxalate showed maximum % retention (50% at 5 mg/kg and 75% at 10 mg/kg) in the elevated plus maze test and maximum % inhibition (71% at 25 microM) of AChE on biochemical evaluation.

Ab initio study of nitrogen-multisubstituted neutral and positively charged C20 fullerene

Ab initio investigation of structural and electronic properties of Nitrogen doped fullerenes, obtained from C20 by replacing up to 10 C atoms with N atoms, are studied by means of first principals density functional theory calculations using numerical orbitals as basis sets. We have obtained the ground state structures for C20−nNn for n=1-10. While substituting nitrogen atoms, we cannot substitute more than 9 nitrogen atoms. Nitrogen doping in C20 shows a significant change in density of states. For a better comparison with experimental measurements, we have also considered some positively charged ions and report the differences between properties of these ions and the corresponding neutral molecules.

Effect of hydrostatic pressure on the structural and electronic properties of Cd0.75Cr0.25S

In this paper we present the results obtained from first principle calculations of the effect of hydrostatic pressure on the structural and electronic properties of Cd1-xCrxS diluted magnetic semiconductor in Zinc Blende (B3) phase at x=0.25. High pressure behavior of Cd1-xCrxS has been investigated between 0 GPa to100 GPa The calculations have been performed using Density functional theory as implemented in the Spanish Initiative for Electronic Simulations with Thousands of Atoms code using local density approximation as exchange-correlation (XC) potential. Calculated electronic band structures of Cd1-xCrxS are discussed in terms of contribution of Cr 3d5 4s1, Cd 4d10 5s2, S 3s2 3p4 orbital’s. Study of band structures shows half-metallic ferromagnetic nature of Cd0.75Cr0.25S with 100% spin polarization. Under application of external pressure, the valence band and conduction band are shifted upward which leads to modification of electronic structure

DFT study of Al doped armchair SWCNTs

Electronic properties of endohedrally doped armchair single-walled carbon nanotubes (SWCNTs) with a chain of six Al atoms have been studied using ab-initio density functional theory. We investigate the binding energy/atom, ionization potential, electron Affinity and Homo-Lumo gap of doped armchair SWNTs from (4,4) to (6,6) with two ends open. BE/dopant atom and ionization potential is maximum for (6, 6) doped armchair carbon nanotube; suggest that it is more stable than (4, 4) and (5, 5) doped tubes. HOMO - LUMO gap of Al doped arm chair carbon nanotubes decreases linearly with the increase in diameter of the tube. This shows that confinement induce a strong effect on electronic properties of doped tubes. These combined systems can be used for future nano electronics. The ab–initio calculations were performed with SIESTA code using generalized gradient approximation (GGA).

Structural and electronic properties of GaAs and GaP semiconductors

The Structural and Electronic properties of Zinc Blende phase of GaAs and GaP compounds are studied using self consistent SIESTA-code, pseudopotentials and Density Functional Theory (DFT) in Local Density Approximation (LDA). The Lattice Constant, Equillibrium Volume, Cohesive Energy per pair, Compressibility and Band Gap are calculated. The band gaps calcultated with DFT using LDA is smaller than the experimental values. The P-V data fitted to third order Birch Murnaghan equation of state provide the Bulk Modulus and its pressure derivatives. Our Structural and Electronic properties estimations are in agreement with available experimental and theoretical data.

Cd0.9375Mn0.0625S diluted magnetic semiconductor: A DFT study

We studied the spin polarized electronic band structures and magnetic properties of the diluted magnetic semiconductor Cd1-xMnxS in Zinc Blende phase (B3) with 0.0625 Mn by using ab initio method. The calculations were performed by using Density Functional Theory as implemented in the Spanish Initiative for Electronic Simulations with Thousands of Atoms code using local density approximation (LDA). Calculated electronic band structures and magnetic properties of Cd1-xMnxS are discussed in terms of contribution of Mn 3d5 4s2, Cd 4d10 5s2, S 3s2 3p4 orbitals. The total magnetic moment is found to be 5.00 µb for Cd1−xMnxS at x=0.0625. This value indicate that Mn atom adds no hole carrier to the perfect CdS crystal. We found that Mn doped systems are ferromagnetic. Calculated results are in good agreement with previous studies.

Thermoelectric properties of Al doped Mg2Si material

In the present paper we have calculated thermoelectric properties of Al doped Mg2Si material (Mg2−xAlxSi, x=0.06) using Pseudo potential plane wave method based on DFT and Semi classical Boltzmann theory. The calculations showed n-type conduction, indicating that the electrical conduction are due to electron. The electrical conductivity increasing with increasing temperature and the negative value of Seebeck Coefficient also show that the conduction is due to electron. The thermal conductivity was increased slightly by Al doping with increasing temperature due to the much larger contribution of lattice thermal conductivity over electronic thermal conductivity.

Structural and Electronic Properties of C20‐nSin (n = 1–10)

Ab initio investigation of structural and electronic properties of silicon‐doped fullerenes (C20‐nSin, for n = 1–10) has been performed using numerical atomic orbital density functional theory. We have obtained the ground state structures for C20‐nSin for n = 1–10, which show when we substitute one C atom by silicon atom then binding energy/atom increase sharply, after that binding energy/atom decreases with increase number of silicon atoms, but average diameter increases due to large size of silicon atom as compared to carbon atom. From the analysis of electronic properties, we observe that Ionization potential of silicon substituted C20 increases up to n = 3, and then starts decreases with increase in number of silicon atoms. But it is always more than C20. Therefore Si substituted C20 is less reactive. The results in all cases are consistent with available theory and experimental results.