Defects in the Compound Bi2te3 Caused by Irradiation with Protons

Defects in single crystals of bismuth telluride caused by proton irradiatio

Bioelectrode based chitosan-nano copper oxide for application to lipase biosensor

Chitosan (Chit)-nanocrystalline CuO composite prepared from Chitosan and CuO nanoparticles by a spin coating method. CuO nanoparticles (45 nm) synthesized by Sol-gel citrate method and characterized by X-Ray diffraction (XRD), Raman spectroscopy, UV-visible spectroscopy, Fourier transform spectroscopy (FTIR) and Scanning electron microscopy (SEM). The electrochemical studies revels that these Chit-nano CuO electrode provide favorable condition for immobilization of enzyme lipase [LIP] specific enzyme for triglyceride detection, resulting in enhanced electron transfer at the interface. The prepared bioelctrode (LIP/Chit-nano CuO/Au bioelectrode) is utilized for triglyceride [TG] sensing using cyclic voltammetry (CV) with hexacyanoferrate as mediator. The electrochemical response studies shows on improved sensing performance of bioelectrode exhibit high sensitivity, low detection limit and good linearity of tributyrin concentration with fast response time. The low value of Michallis-Menten constant indicates high affinity of LIP towards the analyte (tributyrin). The Redox behavior of nano CuO makes an efficient matrix with chitosan for triglyceride [TG] biosensor.                                                        &nbsp

Simulations of a weakly conducting droplet under the influence of an alternating electric field

We investigate the electrohydrodynamics of an initially spherical droplet under the influence of an external alternating electric field by conducting axisymmetric numerical simulations using a charge-conservative volume-of-fluid based finite volume flow solver. The mean amplitude of shape oscillations of a droplet subjected to an alternating electric field for leaky dielectric fluids is the same as the steady-state deformation under an equivalent root mean squared direct electric field for all possible electrical conductivity ratio $(K_r)$ and permittivity ratio $(S)$ of the droplet to the surrounding fluid. In contrast, our simulations for weakly conducting media show that this equivalence between alternating and direct electric fields does not hold for $K_r \ne S$. Moreover, for a range of parameters, the deformation obtained using the alternating and direct electric fields is qualitatively different, i.e. for low $K_r$ and high $S$, the droplet becomes prolate under alternating electric field but deforms to an oblate shape in the case of the equivalent direct electric field. A parametric study is conducted by varying the time period of the applied alternating electric field, the permittivity and the electrical conductivity ratios. It is observed that while increasing $K_r$ has a negligible effect on the deformation dynamics of the droplet for $K_r<S$, it enhances the deformation of the droplet when $K_r>S$ for both alternating and direct electric fields. We believe that our results may be of immense consequence in explaining the morphological evolution of droplets in a plethora of scenarios ranging from nature to biology.Comment: 10 pages, 8 figure

Spray Deposited Nanocrystalline ZnO Transparent Electrodes: Role of Precursor Solvent

Nanocrystalline ZnO thin films were deposited by intermittent spray pyrolysis using different alcoholic and aqua-alcoholic precursor solvents. The XRD analysis reveals the polycrystallinity of hexagonal wurtzite type ZnO films with preferred c-axis orientation along [002] direction. The polycrystallinity increased due to use of aqua-alcoholic precursor solvent. The crystallite size was found to vary from 41.7 nm to 59.4 nm and blue shift in band-gap energy (3.225 eV to 3.255 eV) was observed due to aqua-alcoholic to alcoholic precursor solvent transition. The films deposited using alcoholic precursor solvent exhibited high transmittance (> 92 %) with low dark resistivity (10 – 3 Ω·cm) as compared to aqua-alcoholic precursor solvent. The effect of precursor solvent on resistivity, carrier concentration (η – /cm3), carrier mobility (μ – cm2V – 1s – 1), sheet resistance (Ω/) and figure of merit (ΦTC) is also reported. We recommend ethanol or methanol as a superior precursor solvent over aqua-alcoholic precursor solvent for deposition of device quality ZnO thin films

Magnetotransport properties of individual InAs nanowires

We probe the magnetotransport properties of individual InAs nanowires in a field effect transistor geometry. In the low magnetic field regime we observe magnetoresistance that is well described by the weak localization (WL) description in diffusive conductors. The weak localization correction is modified to weak anti-localization (WAL) as the gate voltage is increased. We show that the gate voltage can be used to tune the phase coherence length ($l_\phi$) and spin-orbit length ($l_{so}$) by a factor of $\sim$ 2. In the high field and low temperature regime we observe the mobility of devices can be modified significantly as a function of magnetic field. We argue that the role of skipping orbits and the nature of surface scattering is essential in understanding high field magnetotransport in nanowires