ICRAPID-2014-International conference on Recent Developments in Physics for Interdisiciplinary Developments

"In association with Nobel Laureate and Bhatnagar Awardees"

Electronic and Elastic Properties of Metal Monoxides MO (M=Nb,V):A First-Principles Study[ ]


The first-principles calculations based on density-functional theory (DFT) is a very efficient method to study the properties of materials. We report a detailed study of the structural, electronic and elastic properties of the metal monoxides – Vanadium monoxide and Niobium monoxide - MO (M=V, Nb) in the B1 (rock-salt), B2 (CsCl) and B3 (Zinc-blende) phases, under normal and elevated pressures using the first-principles calculations. To understand the structural and electronic properties of MO (M=V, Nb), their lattice parameters, density of states and electronic band structures are analyzed. The lattice parameters are found to be in accord with the available experimental and other theoretical values. From the electronic band structure, we find that both the metal monoxides are metallic in nature at all pressures. We report a phase transition from B1 to B2 phase at a pressure of 58.85 GPa in Vanadium monoxide. Niobium monoxide in its B2 phase, transforms into a super conductor. The elastic constants are computed at normal and elevated pressures to investigate the mechanical stability, anisotropy and hardness of MO (M=V, Nb). The calculated elastic constants obey the stability criteria only for the B1 and B2 phases of Vanadium monoxide. As for Niobium monoxide, its B2 phase alone is stable in the normal and elevated pressures.

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FTIR and EPR studies of Vanadium ion doped in ZnO-Li2O-Na2O-K2O-B2O3 Glasses[ ]


EPR studies were made on xZnO-10Li2O-10Na2O-10K2O- (68-x) B2O3-2V2O5 glass system in which VO2+ is acting as paramagnetic probe while FTIR studies are conducted on Vanadium free glass samples of the composition xZnO-10Li2O-10Na2O-10K2O- (70-x) B2O3 . The glass samples are prepared by melt quenching method and the amorphous nature of the glass samples was confirmed by X-Ray diffraction studies. From the FTIR studies it was observed that the glass is made up of [BO3] and [BO4] units. From the EPR spectra the spin-Hamiltonian parameters were evaluated. It was observed that the vanadyl (V4+) ions exist as VO2+ ions in octahedral coordination with tetragonal compression and belong to C4v symmetry, with dxy ground state. The measure of tetragonality vary in non-linear manner with glass composition. The covalency rates were estimated. The number of spins participating in the resonance (N) and susceptibility ( ) were evaluated.

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Spin Density Wave Interaction in Two Band Model for the Iron-Based Superconductors[ ]


The newly discovered Oxypnictide superconductors have triggered enormous research interests in the condensed physics.We propose a two band model in presence of spin-density-wave(SDW) interaction to investigate the behavior of itinerant electron on the temperature dependent SDW gap, density of states, effect of doping and specific heat. The SDW gap equation is calculated from electron Green’s function and solved numerically. Using the temperature dependent SDW gap, the density of states,occupation number for the two bands and specific heat are calculated and results are discussed to explain experimental facts .

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UV-Vis, HOMO-LUMO AND HYPERPOLARIZABILITY OF L-PHENYLALANINE L-PHENYLALANINIUM-BENZOIC ACID[ ]


Nonlinear optical single crystal of L-phenylalanine L-phenylalaninium-benzoic acid (LPB) was grown by slow evaporation technique. The grown crystal was subjected to optical characterization by UV-Vis techniques. DFT calculations predicted first order hyperpolarizability of LPB as 4.48715 x 10-30 esu, which suggests that the title compound is an attractive material for non-linear optical applications. The calculated HOMO-LUMO energies show that charge transfer occurs within the molecule. The SHG efficiency was measured using the Kurtz powder technique. The efficiency was found to be higher than that of KDP.

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Linear And Nonlinear Optical Properties Of L- Threonine Acetate[ ]


The optical properties of the grown crystal were studied by means of absorption measurements in the wavelength region between 200 and 1200 nm. Optical behavior has been assessed by UV-Vis analysis and found that there is minimum absorption in the entire visible region. The optical constants such as refractive index (n) and extinction coefficient (k) have been determined from the transmittance data. The optical band gap (Eg) the real and imaginary part of the dielectric constant of the grown crystal was determined. The relative second harmonic generation (SHG) efficiency measurement reveals that the incorporation of Acetic acid to L- Threonine leads to increase in its SHG value.

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Dielectric and Electrical Property of the Anhydrous Diglycine Sulfate (DGS) Single Crystals[ ]


Anhydrous Diglycine Sulfate (DGS) have been grown from aqueous solution of glycine and sulfate with slow evaporation techniques at constant temperature. The complex relative dielectric function e*(?) =e' - je? of mixture of Anhydrous Diglycine Sulfate with water in varying concentration have been measured using precision LCR meter in the frequency range 20Hz to 2MHz at room temperature. The dielectric/electrical properties of the liquid samples are represented in terms of intensive quantities namely, complex relative dielectric function e*(?), conductivity s*(?), electrical modulus M*(?), and extensive quantities, i.e. complex admittance Y*(?) and complex impedence Z*(?). All of these properties are used to explore various processes contributed in the dielectric/electrical presentations of the mixtures.

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Structural, Transport and magnetic Properties of Ca2Zn2Fe12O22Hexagonal Y-Ferrites[ ]


Calcium hexagonal ferrites doped Ca2Zn2Fe12O22 was prepared by solid state diffusion technique. The structural properties of this polycrystalline sample were studied using powder X-ray diffraction method. The XRD pattern showed a single phase of the Y type hexagonal ferrite with lattice parameters a=5.93 Å and c=41.32 Å. The two electrode method was used to study the DC Resistivity of the ferrite between the temperatures from 300 K to 800 K. The resistivity result showed the behaviour of samples as semiconductor. Variation in molar susceptibility of the hexagonal ferrite between temperatures 300 K to 800 K was studied by Gouy’s balance method. This showed the ferrimagnetic behaviour of the sample at room temperature. Its Curie Temperature was found to be 400 K and Curie molar constant was 52.5

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Structural, Vibrational, Thermodynamic and Frontier Molecular Orbital Studies on (GaN)2 : A DFT and MP2 Approach[ ]


We report the structural, vibrational, thermodynamic and frontier molecular orbital (FMO) studies on (GaN)2 using density functional theory (DFT) and ab initio MP2 methods, in conjunction with the 6-31G(d) and 6-311+G(d) basis sets. The investigations carried out also for various temperature and pressure values. The geometries, the Mulliken atomic charges, and HOMO-LUMO energy were calculated for the GaN and (GaN)2 molecules. FT-IR and Raman spectral results were analyzed. Thermodynamic parameters such as thermal energy, thermal correction to enthalpy (?H), thermal correction to Gibbs free energy (?G), constant volume molar heat capacity (Cv) and entropy (S) were calculated for various temperatures and pressures and their results were qualitatively discussed. The results obtained give new insight of the modified structure of semiconducting material GaN. The compound (GaN)2 was found to have high thermal stability and enhanced semiconductor properties compared with the GaN.

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A study on thermochemical properties of ZnS Nanomaterial:A computational Approach[ ]


We report the electronic and thermochemical properties of semiconductor ZnS at various temperature and pressure using density functional theory(DFT), in conjunction with the 6-311+G(d) basis sets. ZnS subjected to electronic calculations in order to calculets its bond length, Mulliken atomic charges, HOMO-LUMO energy, vibrational spectral analysis of FT-IR and Raman. Thermochemical parameters such as thermal energy, thermal correction to enthalpy (?H) and thermal correction to Gibbs free energy (?G), constant volume molar heat capacity(Cv) and entropy(S) were calculated and their results were analysed and interpreted. The results obtained with DFT method give new insight of the ZnS semiconductor material. It was found that for higher temperature the stability of the species high whereas for higher pressure the stability was found to be reducing.

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Effects Of Gamma Irradiation On The Electrical And Optical Properties Of Conducting Poly(N-Methylaniline)[ ]


The effects of gamma irradiation on the electrical and optical properties of conducting Poly(N-Methylaniline) have been studied. The radiations absorbed by the samples were 21.5KGy. The deterioration of chemical bonding with irradiation fluence was found. The conductivity measurement was carried out by using four-probe method in the temperature range 310 K - 370 K. The analysis of conductivity studies shows that the protonation increases in the order 1 M > 0.6 M > 0.4 M > 0.2 M of H2SO4 and the enhanced conductivity of samples due to irradiation. Arrhenius fitting of conductivity curves indicates that the charge transport mechanism was followed by VRH. The SEM images confirmed the morphological changes due to the gamma irradiation.

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?-Ray Attenuation Studies on NaI[ ]


Temperature dependent ?- ray attenuation studies have been carried out by a ?- ray densitometer fabricated in our laboratory. The linear attenuation coefficients (µl) of NaI as a function of temperature in the range 300K-900K have been determined using different energies of ?-beam viz., Am (0.0595MeV), CO(1.173MeV & 1.332MeV). The coefficient of temperature dependence of density has been reported. The variation of density and thermal expansion of NaI in the temperature range have been studied and compared with the results available in the literature. The temperature dependence of linear attenuation coefficient, density and thermal expansion has been represented by second degree polynomials. Volumetric thermal expansion coefficient as a function of temperature has been reported by ?-ray attenuation studies for the first time.

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Temperature dependent density and thermal ex-pansion of 5088 wrought aluminum alloy by Gam-ma Ray Attenuation Technique[ ]


The density and thermal expansion of wrought aluminum alloy 5088 has been measured from 300K - 850K by measuring attenuation of gamma beam of different energies viz, Cs(661.16 KeV), Am (59.54 KeV) Co (1173 KeV& 1332 KeV). The temperature dependence of linear attenuation coefficient (µl) of gamma photons of different energies in the temperature range 300 – 850 K for the alloy has been reported. The gamma ray attenuation studies have been carried out by using a gamma ray densitometer. the variation of density and thermal expansion of the alloy has been represented by linear equations. The coefficients of temperature dependence of density, volume thermal expansion and mass attenuation coefficients have been reported for the alloy.

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Preparation and Characterization of Valine Functionalized Multi-walled Carbon Nanotubes[ ]


The valine functionalized multi-walled carbon nanotubes were prepared and characterized by using Ultraviolet-visible, Fourier transform infrared, Scanning electron microscopy, Energy dispersive X-ray analysis and Electron paramagnetic resonance spectroscopic techniques. UV-Vis study shows the formation of valine functionalized MWCNTs. Fourier transform infrared study confirms the presence of functional groups of oxidized MWNTs and valine functionalized MWCNTs. The morphology study was carried out for oxidized MWCNTs and valine functionalized MWCNTs by using Scanning electron microscopy. The Energy dispersive x-ray spectra revealed that the high purity of oxidized MWCNTs and valine functionalized MWCNTs. The ESR line shape analysis indicates that the observed ESR line shape is a Gaussian line shape. The g-values indicate that the systems are isotropic in nature.

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Study of molecular interactions in binary liquid mixture containing quinoline and cresol by using excess thermodynamic parameters at different temperatures[ ]


In this paper , we have measured the values of ultrasonic velocity, density and viscosity in binary liquid mixtures of a heterocyclic aromatic compound quinoline which is readily soluble in organic solvents cresol at different temperatures over the entire range of composition. From these measured values excess thermodynamic parameters like excess adiabatic compressibility (ßE), excess intermolecular free length(LfE), excess acoustic impedance(ZE), and excess ultrasonic velocity(UE) have been calculated. The calculated deviations in excess thermodynamic parameters have been explained on the basis of the intermolecular interactions present in these mixture.

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Shape Transition Effect of Temperature on MgO Nanostructures and its Optical Properties[ ]


In this paper we report the synthesis of various morphologies of MgO nanomaterials such as nanoflakes, nanoflowers and nanoparticles using magnesium acetate tetra hydrate as a precursor and refluxed at a suitable temperature. The refluxed powder sample is calcined at three different temperatures. The white powder product obtained was characterized by TG/DTA, XRD, HRSEM and photoluminescence (PL). The results showed that the synthesized powder is pure cubic MgO and the grain size increases with increasing temperature. The micro-strain is calculated using Williamson-Hall plot method. HRSEM picture showed that shape changes from nanoflakes to nanoparticle by increasing temperature.

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Structural and Magnetic properties of Strontium Hexa-Ferrites for Permenant Magnets[ ]


Nanoparticles of strontium ferrites with nominal composition SrFe12O19 were prepared by sol-gel method. The as-synthesized sample was characterized by thermo gravimetric analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and Tunneling electron microscopy (TEM). The X-ray powder diffraction results showed that the sample was single phase with the space group of P63/mmc. The lattice constants’ almost remains constant. The crystallite size obtained from XRD data is in the range of 10nm the sample annealed at 800°C. Most of the particles formed had hexagonal structure, as observed by the scanning electron microscopy and The average grain size as determined was found in the range of 35nm. The hexagonal needle-like morphology was obtained by TEM photograph. The crystallite size estimated from X-rays diffraction data was in the range 10nm, which is much smaller than that already reported. The M–H loop indicated that both coercivity and saturation magnetization were 6405 Guass and 28.26emu/g observed at 800°C. This was coincides with theoretical limit. The yield percentage along with structure determination and VSM studies of the prepared samples will be discussed in detail.

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Antimicrobial And Antifungal Activity On Glutathione Stabilized Silver Nanoparticles – An In-Vitro Study[ ]


Silver nanoparticles were obtained by chemical reduction of silver nitrate in water with sodium borohydride (NaBH4) in the presence of glutathione (a tripeptide - biomolecule) as a stabilizer. The synthesized silver nanoparticles were characterized by XRD, UV-Visble spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The antibacterial and antifungal activity of glutathione stabilized silver nanoparticles (GSH-AgNPs) was tested by using Gram-negative and Gram- positive bacteria (Bacillus sp., E.coli, Streptococcus sp., Pseudomonas sp., and Rhizobium sp.) and fungal agents (Aspergillus niger and Candida albicans). The silver nanoparticles, whose bacterial activity was dependent on the aggregation degree between particles, exhibited bacterial activity against Bacillus sp. and similarly for fungal activity against C. albicans. The maximum zone of inhibition (mm) was shown by Bacillus sp. (gram negative bacteria) for antibacterial activity and for antifungal, maximum activity shown by C. albicans for 100µg of the sample.

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Magnetoresistance properties in polycrystalline Gd0.7Ca0.3MnO3[ ]


The magnetoresistance properties in polycrystalline Gd0.7Ca0.3MnO3 have been investigated. The compound crystallizes in orthorhombic structure with Pnma space group. In this work, we have tried to find out the characteristics of temperature dependent resistivity and magnetoresistance properties. The temperature dependent electrical resistivity (?) satisfies the Arrhenius like relation ?/T =?a exp (Ep / KBT) with activation energy (Ep) =156.4 meV. The field dependent resistance at various temperatures shows the hysteresis nature and the hysteresis also increases with temperature. The magneto-resistance (MR) shows a linear dependence with the square of the applied magnetic field. At temperatures 250K, 200K, 150K and 125K the maximum value of magnetoresistance reaches respectively -1.24%, -2.96%, -8.65%, -18.5%

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Effect of Roughness on Surface Magnetism of Fe (001)[ ]


Electronic and magnetic properties of seven layers of bcc Fe are carried out using Augmented Space Recursion (ASR) technique together with tight binding linear muffin tin orbital (TB-LMTO) method. A relativistic self-consistent calculation within local spin density approximation (LSDA) is adopted to generate potential parameters from TB-LMTO Hamiltonian. These parameters are taken as input for ASR calculations. The surface is poisoned with different amount of roughness with random substitution of empty spheres, while the layers beneath the surface remain smooth. Effects of roughness on surface electronic and magnetic properties are studied here. Spin resolved density of states show the effect of roughness on the surface. For all concentration of roughness, magnetic moment of the surface layer is higher than its bulk value. Surface magnetic moment increases with increase in surface roughness.

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The Role of Electrolyte pH in Enhancing the Surface Morphology of TiO2 Nanotube Arrays Grown on Ti Substrate[ ]


Among all transition metal oxides TiO2 has become the most extensively studied and investigated compound in the field of materials science as it gives enormous opportunities to the researchers in the field of nanomaterials. The present work explains the formation of TiO2 nanotube arrays fabricated by electrochemical anodization of titanium in fluoride-based ethylene glycol electrolyte, with an aim towards elucidating how the electrolyte pH influences the electrolyte properties and corresponding morphological features of TiO2 nanotube array films. Commonly employed two electrode anodization setup was used for the purpose. The samples were anodized in different electrolyte compositions to study the effect of pH on the growth rate of TiO2 nanotubes. Concentrated H2SO4 and NH3OH at different molarities were used to vary the pH of the electrolyte solution. The synthesized samples were characterized with FESEM, EDX and XRD to study the morphology and crystal structure of the nanotubes.

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Equivalence of Qudit Gate Operations[ ]


The basic unit of quantum information content is qubit which is usually a two level quantum system. Among the various two qubit gates, the exchange gate, otherwise known as SWAP gate is very fundamental. Extension of quantum operations from two level (qubit) to any arbitrary dimensional level (qudit) is important but not straightforward. The circuit constructions of qudit SWAP operation using various qudit gates are known. In this work, equivalence of some important qudit operations is illustrated. Such equivalence may be exploited to minimize the circuit complexity in the previously proposed qudit SWAP gate constructions.

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Optical and Electrical Studies of Silver Boro Tellurite Glasses[ ]


Super ion conducting glasses of composition 55AgI-22Ag2O-23[(1-x) B2O3-xTeO2] where x=0 to 1 in steps of 0.2 mol% were prepared by melt quenching technique. XRD, FTIR investigations were carried out on all glasses to understand physical characteristics of the prepared glasses. Electrical characterization is done in terms of AC and DC conductivities, activation energy, break down strength, transport number, and equivalent R-C circuits. DC conductivity at room temperature increased from10-4 to 10-2 S/cm with increasing concentration of TeO2. DC activation energy (Edc) is found to decrease from 0.36 to 0.19 eV with increasing concentration of TeO2. The breakdown strength of all the samples is found to be in the range of 2.3 to 1.6 kV/cm. From the Impedance spectroscopy, real and imaginary impedances (Z’, Z”) were calculated, and equivalent R-C circuit parameters were obtained from Nyquist plots for all the samples. AC conductivity is observed to increase whereas the AC activation energy (Eac) is observed to decrease from 0.23 to 0.14 eV with increasing concentration of TeO2. The quantitative analysis of these results indicates that the electrical conductivity of silver borate glasses is enhanced by addition of TeO2. These glasses are identified as superionic conductors, with in which conduction is carried by hopping mechanism.

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Comparison Studies of Quartz And Biosilica Influence On The Porcelain Tiles[ ]


Vitrification of ceramic tiles was investigated by the incorporation of synthesized biosilica from bioresidue of maize stalk. The fully substitution of biosilica in porcelain formulation augments the strength behaviour and to improve the microstrucutral development. The fired specimens of mechanical parameters such as linear shrinkage, water absorption, porosity, compressive strength and young’s modulus were determined. The surface texture of the specimens microstructure development were analysed through Scanning Electron Spectroscopy (SEM). The result that confirms that the biosilica act as a filler in porcelain tiles thus improves the mechanical behaviour of bioceramic tiles than the standard porcelain tiles. The ultrasonic pulse velocity (UPV) of the sintered specimens was correlated with the compressive strength.

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STUDY OF PHYSICAL AND ELASTIC PROPERTIES OF LEAD DOPED MIXED ALKALI BORATE GLASSES USING ULTRASONIC TECHNIQUE[ ]


The quaternary glass system of xLi2O - 50B2O3 – (45-x) Na2O- 05PbO (where x = 20, 25, 30, 35 and 40 mol %) with different composition were prepared by melt-quench technique. The longitudinal and shear ultrasonic velocities were measured for all the glass samples at room temperature and at 10 MHz frequency. Density of the samples was measured using relative measurement method. Elastic modulii, Poisson’s ratio, acoustic impedance, microhardness, Debye and softening temperature and thermal expansion co-efficient were calculated from velocity and density data and have been used to obtain quantitative details about the structure of these glasses. Compositional dependence of ultrasonic velocities and related parameters are discussed to understand the rigidity and compactness of the glass systems studied.

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First Principles Study of Pressure Induced Phase Transition, Electronic and magnetic Properties of Plutonium trihydride[ ]


The structural phase transition, electronic and magnetic properties of plutonium trihydride is investigated using density functional theory calculations with the generalized gradient (GGA) approximations. The calculated equilibrium lattice parameter and bulk modulus are in good agreement with the experimental results. The electronic structure reveals that plutonium trihydride is half metallic ferromagnet at normal pressure. A pressure-induced structural phase transition from hexagonal to cubic phase is observed in plutonium trihydride. On further increasing the pressure, a half metallic to metallic transition is also observed. Ferromagnetism is quenched in PuH3 at high pressures.

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First principles study of Structural, Electronic and Mechanical properties of TiN and TiN2[ ]


The structural, electronic and mechanical properties of TiN and TiN2 are investigated using density functional theory calculations with the generalized gradient (GGA) approximation. The lattice constants, cohesive energy, bulk modulus and the density of states are obtained. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that these materials exhibit metallic behavior at ambient condition. A pressure-induced structural phase transition from NaCl to ZB to WZ phase is observed in TiN whereas in TiN2, CaF2 to FeS2 to AlB2 transition is predicted. The computed elastic constants indicate that these nitrides are mechanically stable at ambient pressure.

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Influence of Magnetic Field on Energy Spectra of a Nano Dot[ ]


We present a theoretical study on donor binding energies of GaAs / Ga1-xInxSb nano dot as a strength of magnetic field along Z direction. Calculations are carried out by using the technique of variational ansatz with in the frame work of effective mass approximation. Our results shows that (i) wave function is unbound for most of the radii of interest and have negative binding energy for lower dot radius (ii) binding energy is increased while increasing the magnetic field as expected.

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Synthesis and Characterization of metallic Indium embedded SiO2 composite nanoparticles by reverse micelle and sol-gel processing[ ]


Metallic In nanoclusters were embedded into SiO2 matrix that were synthesized within reverse micelle via a solution reduction of In(NO3)3 by hydrazine hydrate. The size of the particles can be controlled by manipulating the relative rates of the hydrolysis and condensation reaction of tetraethoxysilane within the microemulsion. The spherical equivalent size for the In clusters formed in SiO2 matrix was estimated to be around (3±1) nm. The presence of In in the matrix was confirmed by EDS spectroscopy. The effects of synthesis parameters, such as the molar ratio of water to surfactant and the mechanism of composite formation are discussed.

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First Principles Study of Structural, Electronic and Elastic Properties of ScH and ScH2[ ]


The Structural, electronic and elastic properties of ScH and ScH2 are systematically studied by employing the density functional theory within generalized gradient approximation. The calculated lattice parameters are in agreement with the available results. Our calculated elastic constants explicitly indicate that these hydrides are mechanically stable. Elastic moduli, Poisson’s ratio and Debye temperature are derived from elastic constants. The electronic structure reveals that the mono and dihydrides of scandium exhibit metallic behaviour at normal pressure. A pressure-induced structural phase transition from ZB to NaCl is observed at a pressure of 4.8 GPa for ScH.

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Influence of Anisotropy in Coulomb Interaction on Density of Electronic States in Iron Pnictide Superconductors[ ]


The present work deals with the tight binding modeling and numerical computation of quasi-particles energy dispersion and density of electronic states (DOS), taking into account electronic correlations and Hund’s coupling along with 3d orbitals (dxz, dyz) features governing the electronic properties in iron pnictides superconductors. The tight binding Hamiltonian containing the inter-band coupling, intra-band and inter band Coulomb corre-lations has been employed for two orbital per site and two tight binding band scenario. Employing, the Green’s function equation of motion approach within BCS mean field approximation in superconducting state of iron pnictides. We have obtained the expression of different quasi-particle energies and electronic density of states as a function of various model tight binding parameters. The energy dispersion at different k point (G (0, 0), X (p, 0) and M (p, p)) of Brillouin zone is numerically computed. It is noticed that the behavior of electronic states is different at each k-point of the Brillouin zone and highly influenced by next nearest neighbor hopping and Coulomb correlation. Through computer stimulation, it is further predicted that inter-band Coulomb correlation establize the superconducting states and quasi-particle energy spectrum possess four quasi-particle energy branches which represent the splitting of electronic states within two band iron pnictides. On increasing the inter band correlation, the quasi-particle energy peak in the spectra show prominent features lying above and below the Fermi surface and support in estabilizing the superconducting state in the presence of anisotropic Cou-lomb correlation in iron pnictides. Finally, the theoretically obtained behavior of quasi-particle energies and density of states has been viewed in terms of recent photoemission ARPES and STM data in iron pnictide superconductors.

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Synthesis and characterization of banana peel derived biopolymer/hydroxyapatite nanocomposite for biomedical applications[ ]


The aim of this study is to prepare and characterize the novel green biopolymer/HAP nanocomposite. In this synthesis process the biopolymer derived from the peel of bananas with different concentrations were used for the synthesis of HAP nanocomposites. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were used to identify the functional groups, phase structure and morphology of the as-synthesized composite. FTIR analysis confirms the COO-….Ca2+ interaction between the as-prepared biopolymer and HAP. The nanocomposite crystal behavior and phase analysis using XRD analysis shows the formation of phase pure nanocomposite with low crystalline nature. The morphology of the as-synthesized sample was investigated using SEM and TEM analysis which demonstrates the presence of discrete particles with reduced size. Hence, the as-synthesized nanocomposite could have a potential application in the various biomedical fields.

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Coating of strontium substituted hydroxyapatite on surface treated surgical grade stainless steel by electrodeposition for biomedical applications[ ]


Surgical grade stainless steel (316L SS) is one of the widely used implant material in orthopedic surgeries. But often the release of metal ions is evidenced from the implants and subsequently a second surgery is required to remove the implant material. One way to control the release of metal ions is to coat the implant material with a biocompatible material like hydroxyapatite (HAp). Strontium (Sr) salts were found to stimulate bone formation and inhibit bone resorption both in vitro and in vivo. The present work deals with the electrodeposition (ED) of Sr substituted hydroxyapatite (Sr- HAp) on the HNO3+H2SO4 treated 316L stainless steel (316L SS) at a current density of 2 mA/cm2 for different durations like 15 min, 30 min and 45 min. The resultant coatings were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The SEM results revealed that the Sr-Hap coating obtained on the surface treated 316L SS by electrodeposition for 30 min consists of nanorods of dimension ranging from 50 to 75 nm.

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Influence of Synthesis Temperature on Growth of Silver Nanorods[ ]


Silver nanorods (Ag NR) have been successfully synthesized by wet chemical method (seed-mediated growth) utilizing 10 nm silver nanospheres as a seed material and subsequent reduction of silver precursor with a weak reducing agent (ascorbic acid) along with a directing surfactant. The effect of synthesis temperature on the structure, morphology, composition and optical properties were investigated through X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, UV-Vis and FTIR spectroscopy. Both XRD and SAED patterns demonstrate that silver nanorods are crystallized in face centered cubic symmetry. The synthesis temperature significantly influences the morphology of the nanorods. Absorbance spectra confirm the nanorods formation with two SPR bands, one at lower wavelength side and another at higher wavelength side. The results show that increase of synthesis temperature led to decrease of aspect ratio of nanorods.

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Synthesis of ZnO/CuO Nanocomposite and Optical Study of Ammonia (NH3) Gas Sensing[ ]


This article describes the synthesis of ZnO/CuO nanocomposite with the average crystallite size ~ 21nm through sol–gel and hydrothermal synthesis using Tetraethyl ammonium bromide (TEAB) as a surfactant. Crystallinity, average crystallite size were confirmed by X-ray diffraction analysis (Scherer’s method), and morphology were confrmed by Scanning Electron Microscopy. Using the optical properties (PL) interaction between ammonia gas (25ppm) and ZnO/CuO nanocomposite nanostructures were also investigated.

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Investigation of Lead Sulphide nanoparticles synthesized by hydrothermal method[ ]


Single-crystalline lead sulfide nanostructures were synthesized by a simple hydrothermal solution route. Cubic shaped PbS nanocrystals were synthesized using Lead(II) acetate trihydrate, Thioglycolic acid and Thiourea and treated at 180 ºC for 20 hours. The reaction products were characterized by means of X-ray diffraction [XRD] studies confirming the highly crystalline cubic PbS phase formation. Scanning Electron Microscopy [SEM] study revealed cube like structures. From the UV-visible (UV-Vis) spectroscopy, the absorption spectrum indicates a blue shift in the band gap compared to the bulk PbS.The Photoconductivity studies and dielectric analysis were also carried out.

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Copper Nanoparticles: Green Synthesis and Characterization[ ]


Present work describes the synthesis of copper nanoparticles using papaya extract as a capping agent. The preparation of copper nanoparticles by using papaya extract has desired quality with low cost and convenient methods. The papaya extract was mixed with copper salt solution by heating to a temperature of 50-60°C and the reduction reaction was studied by observing the color change. The resulting copper nanoparticles were characterized by UV Visible Absorption Spectrometer, X-Ray Diffraction (XRD), Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) experiments. X-ray diffraction analysis shows that the particles are FCC crystalline in nature. The FTIR spectrum analysis has confirmed the presence of functional groups of stabilizer papaya in capping the copper nanoparticles. SEM and TEM results display the formation of copper nanoparticles with an average size of 20 nm. Copper nanoparticles exhibit an absorption peak at around 560 nm.

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Structural, Electronic and Elastic Properties of LiXN (X = Be, Mg): A First Principles Study[ ]


The structural, electronic and elastic properties of LiXN (X = Be, Mg) are investigated by first principles calculation based on density functional theory using Vienna ab-initio simulation package. Electronic structure reveals that these alloys exhibit semiconducting behavior and a – phase is the most stable phase. The calculated elastic constants indicate that these materials are mechanically stable at ambient condition.

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Half Metallic Ferromagnetism in Alkali Metal Nitrides XN (X= Li, Na): A First Principles Study[ ]


The structural, electronic and elastic properties of two alkali- metal nitrides (XN: X= Li, Na) are investigated by the first principles calculations based on density functional theory as implemented in Vienna ab-initio simulation package. At ambient pressure both nitrides are stable in the ferromagnetic state with NaCl structure. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that these materials are half metallic ferromagnets at normal pressure. A pressure-induced structural phase transition from NaCl to ZB phase is observed in LiN and NaN. Half metallicity and ferromagnetism are maintained in both nitrides at all pressures.

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First principles study of Structural, Electronic, Superconducting and Mechanical properties of Titanium Carbide[ ]


The structural, electronic, superconducting and mechanical properties of TiC are investigated using density functional theory calculations with the generalized gradient (GGA) approximation. The lattice constants, cohesive energy, bulk modulus, band structure and the density of states are obtained. The calculated lattice parameters are in good agreement with the available results. The electronic structure reveals that titanium carbide exhibit metallic behavior at ambient condition. A pressure-induced structural phase transition from NaCl to CsCl phase is observed in TiC. The computed elastic constants indicate that these carbides are mechanically stable at ambient pressure.

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Structural and Optical Properties of CuO Nanocubes Prepared Through Simple Hydrothermal Route[ ]


A simple hydrothermal route have been developed for the fabricating cupric oxide (CuO) nanocubes with excellent reproducibility. Copper acetate monohydrate, polyvinylpyrrolidone and sodium hydroxide were used as copper precursor, structural direction agent and accelerator, respectively. The prepared sample was calcined at 500 °C for 3 hours. The growth mechanism of CuO nanocubes was analyzed on the basis of the experimental results. The nanocrystalline CuO powder was characterized by X-ray diffraction (XRD) which result indicates that the obtained nanocubes were well crystalline single phase CuO with (~33nm crystallite size) monoclinic crystal structure. The Williamson–Hall plot was used to distinguish the effect of crystalline size-induced broadening and strain-induced broadening at Full Width Half Maximum (FWHM) of the XRD profile. Scanning Electron Microscopy (SEM) result indicates that the synthesized products are cubic shaped. Fourier Transform Infrared (FTIR) spectra confirmed composition and formation of single phase CuO wherein the characteristic vibrational modes of Cu–O were identified. The optical analysis by UV–vis diffuse reflectance (DRS) spectroscopy showed that these CuO nanocubes have considerable blue shift in the optical band gap energy (Eg = 1.42eV) due to quantum confinement effect. The high absorbance of synthesized nanocrystalline CuO powder indicates the applicability of using it as an absorbing material in solar cells.This method is low cost, fast, mild and environmental friendly rout to produce high-quality CuO nanoparticle.

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Optical studies on ClAlPc (dye) decorated porous silicon for solar cell application[ ]


This Nanostructured porous silicon (PS) samples were prepared at a current density of 30 mA/cm2 for etching periods 10, 20, 40 and 60 minutes. Then the surfaces of these PS samples were sensitized with derivative of Chloroaluminum Pc (ClAlPc) which is having higher solubility than Phthalocyanines. Then the effect of this dye ClAlPc on PS prepared at different etching periods are investigated using UV-vis absorption and Photoluminescence (PL) emission techniques. The minimum PL emission intensity shown by dye sensitized PS prepared at current density of 30mA/cm2 and etching time period of 60 min reveals that it has good absorbance of radiation.

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Effect of Torsion Angle in Molecular Devices: An Investigation on Electron Transport Properties of Borazine Dimer[ ]


Using Extended Huckle Theory (EHT) combined with nonequilibrium Green’s functions (NEGF), the effect of torsion angle on electron transport properties of borazine dimer-based molecular devices have been investigated.The electron transport characteristics of the borazine dimer system for different torsional angles were analyzed through current–voltage characteristics, transmission spectra and density of states. By changing the torsion angle between two borazine rings, namely changing the magnitude of the intermolecular coupling effect, a different transport behavior can be observed in these systems. Our results show that the torsional angle plays a crucial role in determining the overall conductivity of the molecular devices.

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Preparation, Micro structural characterization and Optical characterization of pure and Gd-doped ceria thin films[ ]


The growth of Gadolinium doped ceria thin films with controlled surface structure for device applications presents a significant problem for experimental investigation. In the present study pure Cerium oxide and gadolinium doped cerium oxide thin films were prepared by pulsed laser deposition [PLD] and were studied for their surface structure evaluation in relation to the optimized operating conditions during the stage of film preparation. The deposition was made with gadolinium concentration of 10mole% to ceria pellets. The films were deposited on quartz substrate in the presence of oxygen partial pressure of 1.5X10-3torr using KrF Excimer laser with laser energy 220mJ at a substrate temperature of 7000 C. The effect of annealing temperature on undoped cerium oxide and 10mole% GDC thin film was investigated. The film thickness was measured by using AMBIOS make XP-1 stylus profiler. As prepared and annealed thin films were characterized for crystallinity, particle size and orientation by using G.I.XRD. The films were characterized using atomic force microscopy [AFM]. The AFM results gave a consistent picture of the evolution of GDC film surface morphologies and microstructures in terms of surface roughness, grain distribution and mean grain size. The optical transmittance spectra was used to determine the optical constants such as optical band gap, refractive index of as prepared and annealed thin films.

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Detection of NO2 using Cavity Enhanced Absorption Spectroscopy in 405nm regime[ ]


Cavity Enhanced Absorption Spectroscopy is noninvasive technique to detect trace gas species. Here we demonstrate an instrument based on CEAS for detecting the trace gas NO2, which is having very low concentration in ambient atmosphere. Variation in the concentration of NO2 in ppb level itself could create great impact on atmosphere. By using high reflectivity DBR mirrors we designed very high finesse optical cavity. Using a 405nm Diode laser as source, Output of the cavity is analyzed using a photomultiplier tube (PMT). NO2 is having absorption in the region 400-405nm which is also Ozone free zone (absorption of ozone is negligible). By using a Data Acquisition System (DAQ) the output from the PMT is coupled into a computer. Using LabVIEWTM software we interfaced the DAQ and analyzed the data using the same GUI based programming. NO2 produced in the lab setup was detected using the developed instrument and concentration of the NO2 is calculated.

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Crystal Growth and Characterization of a new semiorganic nonlinear optical crystal L-Histidine potassium chloride[ ]


A Semiorganic nonlinear optical material L-Histidine Potassium Chloride(LHPC) single crystals were grown by slow evaporation technique. The grown crystal of LHPC is transparent and colourless. The grown crystals were characterized by powder X-ray diffractometry (XRD) method. The XRD pattern confirms the crystalline nature and the purity of the grown crystal. UV-Vis spectrum showed that good optical quality of LHPC. The functional group frequencies were identified and assigned from FTIR spectra. The excitation and emission spectra of LHPC were recorded using spectrofluorometer. The emission peak was absorbed at 306 nm and the optical band gap energy was estimated as 4.06 eV.

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Electronic Structure and Structural Phase Sta-bility of BaFe2As2 Compound under Pressure.[ ]


The electronic band structure and structural phase stability of BaFe2As2 compound has been studied using Quantum Espresso code. To study the structural stability and phase transition, the total energies of this compound have been computed as a function of reduced volumes and fitted with Brich Murnaghan equation. The estimated lattice parameters are in good agreement with available experimental data. The present calculations reveal that BaFe2As2 compound undergo structural phase transition from Tetragonal (T) into Collapsed Tetragonal (cT) phase under pressure. The calculated phase transition pressure is in good agreement with recent experimental data. The calculated valence charge density of collapsed tetragonal phase reveals that As-As interactions is becoming stronger under pressure.

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Electronic Structure and Structural Phase Transition of EuCo2As2 under Pressure[ ]


The electronic structure and structural phase stability of EuCo2As2 compound is studied using the Full Potential Linearized Aug-mented Plane Wave (FP-LAPW) method implemented in WIEN2K. To study the structural stability and phase transition, the total energies of this compound have been computed as a function of reduced volumes and fitted with Brich Murnaghan equation. The estimated lattice parameters are in good agreement with available experimental data. The present theoretical calculations reveal that EuCo2As2 undergo a structural phase transition from Tetragonal phase into Collapsed Tetragonal phase under pressure at about 4.0 GPa. The estimated phase transition parameters are in good agreement with recent experimental data.

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Structural and magnetoelectric studies on Sr2Fe1-xMnxMoO6 (x=0.0,0.25,0.50)[ ]


The present work investigates structural and magnetoelectric properties of Sr2Fe1-xMnxMoO6 (x= 0.0, 0.25, 0.50) series of double perovskite for various potential applications. The Sr2Fe1-xMnxMoO6 compounds were synthesized by solid state route with controlled reducing atmosphere (H2:Ar) and characterized by means of XRD, SEM and FTIR. The XRD showed phase pure compound with tetragonal crystal structure. SEM images gave the single phase morphology and FTIR spectra showed two bands for x=0.0, three bands for x= 0.25 and four bands for x=0.50 compositions. The Cole Cole plot justified the presence of Mn2+ in the material enhancing the dielectric properties. The magnetoelectric characterization of Sr2Fe1-xMnxMoO6 compounds are done and the ME coefficient a is increasing with Mn substitution.

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The Temperature Dependent Electron Transport Studies in a Molecular Device[ ]


The quantum transport through Tour Wires (TWs) was studied at room temperature and high temperature range using nonequilibrium Green’s function (NEGF) formalism combined with extended Huckel theory (EHT). Au-Tour Wire-Au junctions were constructed with functional groups NO2 and NH2.The influence of the temperature effect on the transport characteristics have been emphasized, and the result shows that for the TW and TW-NH2 systems conductance increase with increasing temperature indicating the dominating transport mechanism which is due to thermionic emission. The temperature dependence arises not only from thermal spreading in the leads but also from a thermal average over different contact configuration. In particular, negative differential resistance nature was observed for TW-NO2 at the temperature of 100K in the positive and the negative bias region.

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A Hybrid Network Model for Increasing Bandwidth Using Nano Communication[ ]


Nanotechnology is the manipulation of matter on an atomic and molecular scale. We present the Nanopeers architecture paradigm, a peer-to-peer network of lightweight devices, lacking all or most of the capabilities of their computer-world counterparts. Hence, a P2P Worlds framework as a hybrid P2P architecture paradigm, consisting of cooperating layers of P2P networks, populated by computing entities with escalating capabilities has been proposed. In this paper, we review Nano networks from two aspects briefly: Nano networks with short range and long range communication. We proposed the P2P World framework based on the numerous real-world applications and reduction of complexity in Nano networks with open and well documented protocol specifications.

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Influence of Surface Bonding on Thermo Physical Properties in Silicon Carbide[ ]


In this paper we have studied the influence of size and number of atom-pairs in normalized per atom pair binding (cohesive) energy and melting temperature of the Silica carbide ( ) nano-particle using simple model approach. It is observed that the per-atom-pair binding (cohesive) energy and melting temperature are a quadratic function of the inverse of the particle size for nano-particle. The per atom-pair binding (cohesive) energy and melting temperature comes near that of their bulk value with increasing the particle size and same as the bulk material when the particle size is above than 100 nm.

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Seaweed (Sargassum ilicifolium) assisted green synthesis of palladium nanoparticles[ ]


In the present work, a green route for the synthesis of palladium nanoparticles (PdNPs) has been described. Aqeous extract of the seaweed Sargassum ilicifolium has been used for the reduction of Pd2+ ions to Pd0. The synthesized PdNPs were characterized using UV-vis spectroscopy and Scanning Electron Microscopy (SEM). The particles were well dispersed and spherical in shape. The average size of the PdNPs was found to be 60-80 nm.

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Optical and ESR Studies of Lead Antimony Borate Glasses Doped with V2O5[ ]


Glasses with the composition 30 PbO – 25 Sb2O3 – (45-x) B2O3 – x V2O5 for x = 0 to 1 were prepared in steps of 0.2 by the melt-quenching method. The samples were characterized by X-ray diffraction and differential scanning calorimetric techniques. Various physical parameters, viz., density, molar volume, and oxygen packing density, were evaluated. XRD, DSC, FTIR spectra, optical absorption and ESR spectra at room temperature have been investigated. The variations observed in all these properties due to different concentration of V2O5 have been analyzed. Oxide ion polarizability of all the samples was calculated according to Dimmitrov –Sakka relation. Optical basicity calculation of all the samples was done with the help of J.Duffy equation. Electronic polarizabilities were calculated using Lorentz -Lorentz equation.

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Spectroscopic Study of Interaction Between Extracellular Fungal Proteins and Biosynthe-sized Silver Nanoparticles[ ]


Aspergillus foetidus have been used to synthesize biological silver nanoparticles and extracellular proteins were also isolated from the same strain. The interaction between fungal isolated protein and silver nanoparticles was investigated by UV- Vis spectroscopy, fluorescence spectroscopy and circular dichroism technique. UV- Vis spectroscopic data demonstrates that formation of the complex between fungal proteins and silver nanoparticles occur. Fluorescence spectrum results clearly suggest that silver nanoparticles have a strong ability to quench the intrinsic fluorescence of protein by quenching mechanisms. The number of binding sites ‘n’ and binding constants ‘K’ were calculated according to the relevant fluorescence data. Thermodynamic parameters ?H, ?G and ?S were calculated at different temperatures and the results showed that Van der Waals force and hydrogen bonding played a major role. Negative ?G values imply that the binding process is spontaneous. Circular dichroism results also revealed a conformational change.

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Studies on Noise measure ratio in Heterojunction Avalanche Transit Time Diode at W-band window frequency[ ]


A detailed study on the noise measure has been carried out in Si/Si0.9Ge0.1 heterojunction (p+pnn+ structure with p+ = Si1-xGex, p = Si1-xGex, n = Si and n+ = Si; mole fraction x = 0.1) and Si homojunction DDR Impatt at 94 GHz window frequency. The simulation study reveals that the noise measure for Si based Impatt is 12 times greater than that of Si/Si0.9Ge0.1 heterojunction Impatt at bias current density of 0.3×108 A/m2. However the Noise Measure Ratio decays sharply with increasing current density, but still exhibits better noise performance for heterojunction IMPATT than homojunction Impatt by a factor of 1.75 at bias current density of 2×108 A/m2.The result also shows that the noise measure decreases with increasing value of negative resistance of the device.

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A comparative study on optimized bias current density performance of ß–GaN Avalanche Transit Time diode at Ka-band and Terahertz frequency[ ]


The Terahertz (THz) and Ka-band performance of Zinc-Blende (ß-phase) of GaN based p+pnn+ DDR IMPATT has been studied at optimum bias current density. The study based on drift diffusion model has been carried out to explore the DC and small signal properties of the device. The bias current optimization based on maximum conversion efficiency and device negative resistance reveals the strong potentiality of ß-GaN DDR IMPATT as a powerful solid state source for generating high power at Ka-band and THz frequency. At Ka-band (35 GHz) the conversion efficiency obtained is 15% at an optimized current density of 3.2×109 A/m2 while the same at the THz frequency (0.3 THz) is 11.5% at 3.1×109 A/m2.

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Vibrational Spectroscopic Studies on Amino acid Doped TGS Single Crystals: An Experimental and Theoretical Approach[ ]


Single crystals of pure Triglycine sulphate (TGS), L-asparagine doped TGS (LATGS) and L-glutamine doped TGS (LGTGS) were grown by the slow evaporation method. The structural characterization was carried out by single crystal XRD technique and found that all the grown crystals crystallize in monoclinic structure. Fourier transform infrared and Raman spectra were recorded and analyzed. The line broadening was observed for L-asparagine doped TGS and L-glutamine doped TGS crystals. The broadening of the spectral line is due to the dopant molecules, which are bigger in size than the glycine molecule. The density functional theory (DFT) method was performed using Gaussian 09 software for obtaining the vibrational wave numbers. The FTIR and Raman spectra were simulated and visualized by using Gauss View 5. A comparison between theoretical frequencies of glycinium ion, glycine zwitter ionic form and experimentally observed FTIR and Raman modes for pure TGS and amino acid doped TGS crystals were discussed. The experimental results agree well with the theoreti-cal results.

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Swift heavy ion induced modification of CdO thin film: Optical and structural studies[ ]


Thin films of cadmium oxide (CdO) were deposited on glass substrate using the sol-gel method by spin coating technique. These prepared films were irradiated by MeV ions of Br and Ni at same fluence 3×1012 ions/cm2. The structural properties were studied using X-ray diffraction and it shows that the average crystallite size of CdO films is observed to decrease by the irradiation. The atomic force microscopy (AFM) study of the films shows that the roughness of the films varies with different fluence. The maximum transmittance is observed to be 90 % in the visible region for Ni ion. It is also shown that the band gap of CdO is varied using the swift heavy ion irradiation.

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Infrared and Raman Spectroscopic Studies on mixed alkali tungsten based glasses[ ]


Quaternary tungstate glasses containing K2O, Na2O and B2O3 have been prepared by melt quench technique and studied by IR and Raman spectroscopy. Raman and infrared spectroscopy have been employed to investigate the (30-x)Na2O–xK2O–10WO3–60B2O3 glasses in order to obtain information about the competitive role of WO3 and B2O3 in the formation of glass network. IR spectral study reveals the existence of BO3 and BO4 groups with W-O-W vibrations in the present glasses. Raman scattering study of the present system to understand the role of the mass of the cation in determining the B-O network in glasses. Raman results show that lighter cations favour a stronger B-O network in which three-dimensional BO4 groups are attached to a large borate ring while the heavy cations are not easily inserted in the network interstices. The introduction of heavy cations favours the formation of non-bridging oxygens which make the B-O network comparatively weak. The observation of disappearance and reappearance of IR and Raman bands as a function of various alkali concentrations is an important result pertaining to the mixed alkali effect in borate glasses. Acting as complementary spectroscopic techniques, both types of measurements, IR and Raman, revealed that the network structure of the studied glasses is mainly based on BO3 and BO4 units placed in different structural groups, the BO3 units being dominant. The measured IR and Raman spectra of different glasses are used to clarify the optical properties of the present glasses correlating them with their structure and composition.

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Spectroscopic Studies on B2O3–ZnO–Bi2O3–V2O5 glass system[ ]


Quaternary bismuthate glasses containing V2O5, ZnO and B2O3 have been prepared by melt quench technique. The amorphous nature of these samples was confirmed from their X-ray diffraction. Raman and infrared spectroscopy have been employed to investigate the xB2O3–(85-x) Bi2O3–10ZnO– 5V2O5 where (0

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Mass Attenuation Coefficient for Alprazolam Drug: A Non-destructive Quantitative Analysis [ ]


Analysis of the pharmaceutical drug quality and quantity were done by determining the mass attenuation coefficient. by adopting a non-destructive spectrometric analysis technique. Alprazolam is a psychoactive drug manufactured by different laboratories and also marketed by different brand names viz., Trika Restyl and Alprax. Mass attenuation coefficient for these drug samples were determined at different X-Ray energy range from 8.04 keV to 44.48 keV obtained from the Am-241 radioactive variable energy X-ray (VEX) source. Intensities were measured with and without the attenuator of the each sample with the help of HPGe detector system coupled to multichannel analyser (MAC) through transmission beam geometry. Experimentally determined mass attenuation coefficient values are compared with the therotically estimated values (WinXCom). Quantities of inactive gradients added by the manufacturer were also discussed in this paper.

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Optical Spectroscopy Of V838 Monocerotis[ ]


The star known as V838 Mon underwent an eruption in 2002. Its spectrum has been evolving to later types since then. There are some theoretical models which try to explain the nature of this object, but none has satisfactorily explained all the observed features. Optical spectra of this star have been obtained from the 2m HCT. To understand the post outburst spectral evolution of V838 Mon (A spectrum obtained on 24 mar 2006 has been analyzed).

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Structural Analysis of early-type galaxies-Near IR observations[ ]


Photometric structural parameters and their correlations are significant in understanding the formation and evolution of galaxies. Our sample includes nearby early type galaxies with the presence of ionized gas. The sample galaxies have a wide range of velocity dispersion and their red shifts are less than 5500 km/s. Most of our galaxies are from low density environments. 2MASS (Two Micron All Sky Survey) K-band images were used for photometric analysis. The galaxy components are extracted by two dimensional fitting using the code GALFIT. Structural analysis suggests the presence of significant exponential disc component in our sample galaxies. Average value of B/T is 0.425 and the standard deviation is 0.145.

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Optical Properties of Bright X-ray Sources in NGC 1399: Colour-X-ray Luminosity Correlation[ ]


Unresolved stellar populations in nearby galaxies contain valuable information regarding the formation of the galaxies. Many of such luminous point sources are detected to be brighter X-ray sources including ultra luminous X-ray sources (ULXs) which exhibit emission at super Eddington rates. We perform the aperture photometry of the optical counterparts of the bright X-ray sources in NGC 1399 with an aim to investigate their X-ray to optical association. Our sample includes 29 X-ray point sources (Lx = 1038 erg/sec) in NGC 1399 of which five are ULXs. We observe that the X-ray luminosities are anti-correlated with F475W-F814W colours excepting the two ULXs, the linear correlation coefficient being -0.92 with a significance greater than 99.99%. As the optical counterparts are definitely multiple sources, the strong correlation exhibited by X-ray sources suggests the possibility of existence of multiple sources for the production of X-rays also. This suggests that the energy production in ULXs may be different from other sources in our sample, as they do not follow the correlation.

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Effect of nuclear deformation in proton radioactivity[ ]


The separation energies are calculated for the low and medium mass drip line nuclei in the periodic table. The mass excess values for the nuclei are taken from Wang, Audi-Wapstra mass table (Wang et al., 2012). The possible proton emitters are identified using this separation energy calculation as Sp < 0. The shape of the single proton emitters are calculated using deformation parameters applying tuned Cranked Nilsson model with Strutinsky shell correction approach in the chosen drip line nuclei. Odd Z are found to be good proton emitters and much deformed than their even Z neighbors. This is due to the reason that pairing correlations are strongly reduced in odd Z nuclei and as a result the nucleus is driven towards larger deformation. For nuclei, far from stability, have significant shape deformation in their ground state. This is reflected in the calculations of quadrupole deformation parameter. Nuclear structural changes are analyzed and decay probabilities are calculated. Obtaining more precise data on deformed and nearly spherical proton emitters will help one to test the models of proton radioactivity decay rates.

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Angular dependence of 662 keV multiple backscattered gamma photons in Aluminium[ ]


In Compton backscattering experiments, the energy and intensity of backscattered radiation vary with the angle between primary and scattered radiation. When gamma rays are allowed to interact with thick targets, they undergo number of scatterings within the dimensions of the target before they escape from it, and thus resulting in multiple scattering of gamma-ray photons. Gamma-ray backscattering is very important to get useful information about shielding, dosimetry and non-destructive testing.In the present study, multiple scattering of 662 keV incident photons from 137Cs (214 MBq) gamma source is measured as a function of target thickness for aluminium target. The backscattered photons from the samples are detected by a NaI (Tl) scintillation detector placed at backscattering angles of 35?, 45?, 55?, 65?, 75?, 85?, 95?, 105?, 115?, 125? and 135?. The singly scattered events are reconstructed analytically to get multiple scattering photons. We found multiple scattering increases with increase in sample thickness and saturates after a particular value called saturation thickness. The saturation thickness behaves differently in the two hemispheres and shows symmetry around 90?. The optimum thickness at which the multiply scattered events saturate is also evaluated. Experimental results are compared with Monte Carlo N Particle code and are in good agreement.

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Effective atomic number of composite materials by Compton scattering - nondestructive evaluation method[ ]


Nondestructive evaluation (NDE) technique is a method to evaluate the properties of a material without damaging it. Gamma backscattering is one of the nondestructive evaluation methods that have an advantage of one side access of the material under study. The ability of gamma rays to penetrate deep in material makes its attractive for using it in NDE applications. The multiple scattering of gamma photons acting as a background in the study of Compton profiles can be used as an experimental technique to evaluate “effective atomic number” of composite materials. An intense collimated beam originating from 137Cs (214 MBq) gamma source is made to irradiate copper, iron, aluminium, carbon, brass and polyvinyl chloride plates of dimensions 100 mm × 100 mm × 10mm. Backscattered photons are detected by a NaI(Tl) detector placed at a backscattered angle of 100?. Single scattered photons are obtained by analytical calculation to extract multiple scattered photons from the backscattered spectrum. It was observed the multiple backscattered photons increase with an increase of target thickness and then saturates. The best fit curve of saturation thicknesses versus atomic number of copper, iron, aluminium and carbon is used to assign effective atomic number of composite material. Experimental results are compared with Monte Carlo N Particle code and are in good agreement.

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Experimental Observation of Energy Dependence of Saturation Thickness of Gamma Photons in Iron[ ]


Multiple scattering of gamma photons scattered backwards from iron targets is studied to estimate energy dependence of saturation thick-ness. Collimated beam, obtained from 203Hg, 133Ba, 22Na, 137Cs, 65Zn and 60Co gamma sources is allowed to impinge on rectangular iron targets of dimension 100 mm × 100 mm. The scattered photons from the samples are detected by a 3? × 3? NaI (Tl) scintillation detector placed at a backscattering angle of 180°. We observed that the multiple scattered photons increase with an increase of target thickness and then saturates. The measured saturation thickness for multiple backscattering of gamma photons is found to be increasing with increase in energy of incident gamma photons. The experimental results are compared with results obtained by Monte Carlo N-Particle (MCNP) simulation code.

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Existence and Stability of Dark Solitons in Bose-Einstein Condensate in Parabolic Trapped Optical Lattice[ ]


In this paper, we consider dark solitons in one-dimensional Bose-Einstein condensate in parabolic trapped optical lattice. Analytical and numerical calculations are performed to determine the existence and stability of dark solitons. Our analysis is based on continuous Gross-Pitaevskii equation and discrete nonlinear Schrodinger equation. We show that the strength of external magnetic trap can change the stability of dark solitons. Stability windows of dark solitons are presented and stability approximations are derived using perturbation theory, with numerical results.

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An Improved Bridgeless SEPIC PFC Converter[ ]


In power electronic converters, active power factor correction circuits (PFC) are employed to correct the power factor and achieve high efficiency. Single-ended primary inductor converter (SEPIC) can provide a high power factor. This conventional power factor correction SEPIC suffers from high conduction loss at the input bridge diode. To overcome this problem, a bridgeless SEPIC converter with ripple-free input current is proposed. In the proposed bridgeless converter, the input bridge diode is removed and the conduction loss is reduced. The input current ripple is reduced by means of an auxiliary circuit. The auxiliary circuit consists of an additional winding of the input conductor, an auxiliary small inductor and a capacitor. In this converter, the input current in a switching period is proportional to the input voltage and near unity power factor is achieved. Thus the proposed converter has the advantages of both reduction of ripple current and conduction losses which increases the efficiency of the converter and it is also capable of efficient power factor correction. The operating principles and the waveforms of the converter are analyzed and the performance of the proposed converter is verified by MATLAB simulations.

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Generation of Ultrashort pulses in a Highly Nonlinear Negative Index Material[ ]


In this paper, we consider the electromagnetic pulse propagation in a highly nonlinear negative index material wherein the pulse proagation is governed by cubic-qunitic nonlinear effects. By adopting coupled amplitude phase technique, we delineate the generation of ultrashort pulse in terms of bright soliton. In addition, we also calculate the peak power and pulse width required for generating this ultrashort pulse.

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Natural Sensitizers for Dye Sensitized Solar Cell Applications[ ]


In the Present work, Dye Sensitized Solar Cells were assembled with the natural dyes extracted from three different flowers, namely, Nerium Oleander, Buogainvillea and Hibiscus. The ethanolic extract of the dyes were subjected to UV-Vis absorption and emission spectroscopic studies inorder to confirm the presence of anthocyanin and betalain. The DSSC’s were assembled with the extracted dyes using standard fabrication procedures and tested under 85 mW / cm2 solar simulation for their photoresponses. Of the three dyes tested onto the fabricated DSSC’s, the dye extracted from red hibiscus exhibited best conversion efficiency with a maximum open circuit voltage (VOC) of 0.515 V , short circuit current density (JSC) of 0.765 mA/ cm2 , fill factor (FF) of 0.479 and a overall conversion efficiency (?) of 0.19%. The other two dyes, obtained from Nerium Oleander and Buogainvillea also showed photoresponses under similar irradiation conditions.

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Green Synthesis and Antibacterial Effect of Silver Nanoparticles Using Aspergillus flavus in combination with Gemifloxacin[ ]


Nanotechnology is one of the finest fields of research and technology and has achieved the great progress in medical sciences. Green synthesis has importance in the study of nanoparticles’ production instead of chemical and physical approaches, which has led to the development of bio mimetic approaches for the advanced nanomaterials. The present study focused on novel biological method for the extracellular synthesis of silver nanoparticles using the fungus Aspergillus flavus. The color of the solution changed upon addition of the AgNo3 to the cell free extract in the conical flask indicated the formation of AgNPs. These nanoparticles were further characterized by FESEM and AFM which showed little monodispersity in shape and size within the range of 50-70nm and also the roughness of the silver nanoparticles. The AgNPs synthesized from Aspergillus flavus showed wider antimicrobial properties with the enhancement of bactericidal property against selected pathogens in combination with Gemifloxacin, which would be a novel substituent in the place of high dose antibiotics.

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Crystal Growth and Dislocation Etching of Bi0.75Sb0.25 Alloy[ ]


Bi0.75Sb0.25 single crystals have grown using the zone melting technique. The freezing interface temperature gradient of 300C/cm has been found to yield good quality crystals obtained at the growth rate of 0.5 cm/h. The as-grown crystals have been observed to exhibit certain typical features on their top free surface. Using SEM, FTIR and EDAX technique have characterized the surfaces of the crystals and proportion. A new dislocation etchant has been developed to give reproducible etch-pitting on cleavage surface. Tests of this dislocation etchant have been carried out successfully to revealed the new dislocations and the dislocation density in the crystals of the order of 10-4 cm-2. The results are discussed in detail.

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