Petroleum hydrocarbons and trace metals in Visakhapatnam harbour and Kakinada Bay, east coast of India

148-150High concentrations of PHC were observed in the inner channels (viz., South lighter canal, Northern arm, North western arm and Western arm) of Visakhapatnam harbour. The estimation of trace metals (Cu, Zn, Pb, Cd, Co, Ni and Cr) in surficial sediments indicated higher contamination in Visakhapatnam harbour than in Kakinada Bay. Positive correlations between Cu, Zn, Pb and Cd suggests common sources of these metals. Lack of correlation between Co, Ni with the other metals indicates point sources. High concentrations of chromium reflects intense discharges due to electroplating and battery operations

On watermass mixing ratios and regenerated silicon in the Bay of Bengal

56-61Regeneration of silicon on mixing in the Bay of Bengal have been computed from six water masses [Bay of Bengal low saline water (BBLS), Bay of Bengal subsurface water (BBSS), northern southeast high salinity water (NSEHS), north Indian intermediate water (NIIW), Indonesian throughflow water (ITW) and Antarctic bottom water (AABW)]. The distribution of watermass fractions showed that BBLS with a maximum of 80-90% in the 40-60 m depth range and BBSS with 50% in the 150-300 m depth range are prominant. In the intermediate layers, NIIW shows a maximum percentage of 40% in 250-700 m depth region while ITW shows a maximum of 60% in 800-1000 m depth region. The deeper layers (below 3000 m) are predominantly occupied by AABW with a maximum of 70%. Silicon regeneration consequent upon watermass mixing has been worked out based on the characteristics of silicon for individual watermass

Wigner Crystallization in a Quasi-3D Electronic System

When a strong magnetic field is applied perpendicularly (along z) to a sheet confining electrons to two dimensions (x-y), highly correlated states emerge as a result of the interplay between electron-electron interactions, confinement and disorder. These so-called fractional quantum Hall (FQH) liquids form a series of states which ultimately give way to a periodic electron solid that crystallizes at high magnetic fields. This quantum phase of electrons has been identified previously as a disorder-pinned two-dimensional Wigner crystal with broken translational symmetry in the x-y plane. Here, we report our discovery of a new insulating quantum phase of electrons when a very high magnetic field, up to 45T, is applied in a geometry parallel (y-direction) to the two-dimensional electron sheet. Our data point towards this new quantum phase being an electron solid in a "quasi-3D" configuration induced by orbital coupling with the parallel field

Application of Graphene within Optoelectronic Devices and Transistors

Scientists are always yearning for new and exciting ways to unlock graphene's true potential. However, recent reports suggest this two-dimensional material may harbor some unique properties, making it a viable candidate for use in optoelectronic and semiconducting devices. Whereas on one hand, graphene is highly transparent due to its atomic thickness, the material does exhibit a strong interaction with photons. This has clear advantages over existing materials used in photonic devices such as Indium-based compounds. Moreover, the material can be used to 'trap' light and alter the incident wavelength, forming the basis of the plasmonic devices. We also highlight upon graphene's nonlinear optical response to an applied electric field, and the phenomenon of saturable absorption. Within the context of logical devices, graphene has no discernible band-gap. Therefore, generating one will be of utmost importance. Amongst many others, some existing methods to open this band-gap include chemical doping, deformation of the honeycomb structure, or the use of carbon nanotubes (CNTs). We shall also discuss various designs of transistors, including those which incorporate CNTs, and others which exploit the idea of quantum tunneling. A key advantage of the CNT transistor is that ballistic transport occurs throughout the CNT channel, with short channel effects being minimized. We shall also discuss recent developments of the graphene tunneling transistor, with emphasis being placed upon its operational mechanism. Finally, we provide perspective for incorporating graphene within high frequency devices, which do not require a pre-defined band-gap.Comment: Due to be published in "Current Topics in Applied Spectroscopy and the Science of Nanomaterials" - Springer (Fall 2014). (17 pages, 19 figures