Department of Physics

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IIT Jodhpur

In this paper concept of implementation of the soft computing approach is introduced for the environment friendly steel hardening processing unit, i.e. for Plasma Ion Nitriding (PIN) System. In Plasma Ion Nitriding system, a proper and efficient mechanism is required to meet the problem of finding process parameters involved in the surface hardening treatment of different types of steel. The algorithmic model proposed here is meant to facilitate the prediction of values of the process parameters required to be identified for the surface hardening of the steel in the PIN system. Here, an effort has been made to provide an effective and efficient algorithmic solution model for the soft computing based Plasma Ion Nitriding system. © 2012 IEEE.

World University root node

2012 CSI 6th International Conference on Software Engineering, CONSEG 2012

An effective algorithm model for a soft PIN System

Structural and magnetic properties of polycrystalline BiFeO3, Bi0.9Ca0.1FeO2.95, Bi0.9Ba 0.05Ca0.05 FeO2.95, and Bi0.9Ba 0.1FeO2.95 ceramic samples were studied to establish the effects of doping in BiFeO3 on the magnetic property. X-ray diffraction data of the undoped and doped BiFeO3 samples were refined to a rhombohedral structure with space group R3c. X-ray photoelectron spectroscopy study showed the formation of a single-phase in both the undoped and doped BiFeO3 ceramics with Fe in the 3 valence state. Ca doped and Ba-Ca co-doped BiFeO3 ceramic samples show weak ferromagnetic ordering at room temperature. This observation makes Ca doped and Ba-Ca co-doped BiFeO3 samples an interesting material system for magnetoelectric coupling studies. © 2012 American Institute of Physics.

Fulltext

Journal of Applied Physics

Weak ferromagnetic ordering in Ca doped polycrystalline BiFeO3

PbI2 nano/micro crystals are obtained by environmentally- friendly, easily scaled up solvothermal route and subsequent Inorganic-Organic (IO) hybrid nano/micro crystals of (C12H25NH 3)2PbI4 (20nm to about 7μm) are produced by intercalation of organic moiety. © 2012 OSA.

2012 International Conference on Fiber Optics and Photonics, PHOTONICS 2012

Fabrication of excitonic luminescent inorganic-organic hybrid nano and microcrystals

Using all atom molecular dynamics simulations, we report spontaneous unzipping and strong binding of small interfering RNA (siRNA) on graphene. Our dispersion corrected density functional theory based calculations suggest that nucleosides of RNA have stronger attractive interactions with graphene as compared to DNA residues. These stronger interactions force the double stranded siRNA to spontaneously unzip and bind to the graphene surface. Unzipping always nucleates at one end of the siRNA and propagates to the other end after few base-pairs get unzipped. While both the ends get unzipped, the middle part remains in double stranded form because of torsional constraint. Unzipping probability distributions fitted to single exponential function give unzipping time (τ) of the order of few nanoseconds which decrease exponentially with temperature. From the temperature variation of unzipping time we estimate the energy barrier to unzipping. © 2012 American Institute of Physics.

Journal of Chemical Physics

Unraveling siRNA unzipping kinetics with graphene

Designs of a variety of application-specific Bragg type of microstructured optical fibers are reported. These include fibers for dispersion compensation, metro networks, super continuum generation, lasers at mid-IR wavelengths, and low-dispersion femtosecond pulse transmission. © 2012 OSA.

Microstructured optical fibers: Newest opportunity for fiber designers to realize a myriad of tailored application-specific optical fibers

Nanocrystal formation of SnO 2 in xSnO 2-(100 - x)MgO (x in mol.%) nanocrystalline composite thin films is reported. SnO 2 and MgO exhibit strong immiscibility behavior below 750 °C, leading to controllable particle size of SnO 2 in the MgO matrix by changing their composition. The particle size of SnO 2 can also be controlled by increasing the annealing temperature. Above 750 °C MgO and SnO 2 react to yield a MgO-Mg 2SnO 4-SnO 2 composite in which the size of the SnO 2 nanophase increases with increasing temperature. By controlled choice of the composition and annealing conditions the band gap of SnO 2 can be continuously increased from 3.89 to 4.5 eV. We discuss this behavior in terms of the quantum confinement effect. The method provides a generic approach to tuning the band gap in nanocomposite systems over a wide energy range. © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Acta Materialia

Quantum confinement effects and band gap engineering of SnO 2 nanocrystals in a MgO matrix

We report synthesis of nanosize LiFePO 4 and C-LiFePO 4 powders with a narrow particle size distribution (20-30 nm) by ethanol-based sol-gel method using lauric acid (LA) as a surfactant for high specific capacity lithium-ion battery cathode material. X-ray diffraction measurements demonstrated that the samples were single-phase materials without any impurity phases. The average crystallite size was found to decrease slightly from 29 nm to approximately 23 nm with carbon coating. The ratio of the Raman D-band (∼1350 cm -1) to G-band (∼1590 cm -1) intensities (I D/I G) and electronic conductivity of these materials show strong dependence on the amount of surfactant coverage. Remarkably, cell prepared with carbon-coated LiFePO 4 synthesized using 0.25 M solution of LA showed a very large specific capacity approaching the theoretical limit of 170 mAh/g, in stark contrast to the specific capacity of cell consisting of pure of LiFePO4 (∼75 mAh/g) measured at the same C/2 discharge rate. © Copyright Materials Research Society 2011.

Journal of Materials Research

Nanostructured high specific capacity C-LiFePO 4 cathode material for lithium-ion batteries

In the internal shock model of gamma ray bursts ultrahigh energy muons, pions, neutrons and kaons are likely to be produced in the interactions of shock accelerated relativistic protons with low energy photons (KeV-MeV). These particles subsequently decay to high energy neutrinos/antineutrinos and other secondaries. In the high internal magnetic fields of gamma ray bursts, the ultrahigh energy charged particles ( μ+, π+, K+) lose energy significantly due to synchrotron radiations before decaying into secondary high energy neutrinos and antineutrinos. The relativistic neutrons decay to high energy antineutrinos, protons and electrons. We have calculated the total neutrino flux (neutrino and antineutrino) considering the decay channels of ultrahigh energy muons, pions, neutrons and kaons. We have shown that the total neutrino flux generated in neutron decay can be higher than that produced in μ+ and π+ decay. The charged kaons being heavier than pions, lose energy slowly and their secondary total neutrino flux is more than that from muons and pions at very high energy. Our detailed calculations on secondary particle production in pγ interactions give the total neutrino fluxes and their flavour ratios expected on earth. Depending on the values of the parameters (luminosity, Lorentz factor, variability time, spectral indices and break energy in the photon spectrum) of a gamma ray burst the contributions to the total neutrino flux from the decay of different particles (muon, pion, neutron and kaon) may vary and they would also be reflected on the neutrino flavour ratios.© 2012 Elsevier B.V. All rights reserved.

Astroparticle Physics

Neutrinos from decaying muons, pions, neutrons and kaons in gamma ray bursts

Barium ferrite (hard ferrite) and manganese nickel zinc ferrite (soft ferrite) were successfully synthesized by citrate gel combustion technique. They were used to form the composites by mixing them properly in required compositions (x)BaFe 12O 19-(1-x)Mn 0.2Ni 0.4Zn 0.4Fe 2O 4 (0 x 1). X-ray diffraction (XRD) and scanning electron microscopy (SEM) were utilized to investigate the different structural and morphological parameters of pure and mixed ferrite composites. XRD and SEM results confirmed the coexistence of both phases in the composite material. Moreover, it has been observed that the composites were constituted by nanosized particles. Structure of pure soft ferrite was found to be cubic and that of pure hard ferrite was hexagonal. Dielectric constant (′″) and dielectric loss (tan δ) were analyzed as a function of frequency and composition and the behaviour is explained on the basis of Maxwell-Wagner model. It was observed that the dielectric loss decreases with the increase of hard ferrite content in the composite material. Magnetic measurements suggest the exchange coupling between the magnetizations of soft and hard ferrite grains. It has been observed that the coercivity increases with the increase of the volume of the hard phase in the composite material after an optimal value. © 2012 American Institute of Physics.

Investigation of structural, dielectric, and magnetic properties of hard and soft mixed ferrite composites

We report a shock driven plasma in air breakdown using pump-probe to elucidate the hydrodynamic evolution of air plasma waveguide. Imaging of the evolution of air plasma plume is used to investigate the pump pulse effect on the plume dynamic. Imaging of the channeled pulse through evolved waveguide shows five time enhancement in Rayleigh length at 7 ns delay of probe pulse with respect to pump pulse. The evolved channel radius r ch ≈ 37μm has been shown to couple the maximum energy of the probe pulse yielding the electron density difference δn e ∼ 10 18 cm -3 between axis and periphery of the channel. The air plasma wave guide is shown to support the fundamental mode at optimum delay. © 2012 American Institute of Physics.