Imaging the Near Field

In an earlier paper we introduced the concept of the perfect lens which focuses both near and far electromagnetic fields, hence attaining perfect resolution. Here we consider refinements of the original prescription designed to overcome the limitations of imperfect materials. In particular we show that a multi-layer stack of positive and negative refractive media is less sensitive to imperfections. It has the novel property of behaving like a fibre-optic bundle but one that acts on the near field, not just the radiative component. The effects of retardation are included and minimized by making the slabs thinner. Absorption then dominates image resolution in the near-field. The deleterious effects of absorption in the metal are reduced for thinner layers.Comment: RevTeX, (9 pages, 8 figures

Testudines of India: A Review on Diversity, Threats and Conservation Initiatives

The present review is a collection of the available literature resources related to Testudines of India. Different aspects of diversity studies pertaining to turtles in India is presented in this review along with threats and conservation initiatives in different parts of India in different timeline

Encapsulation of pharmaceutical and nutraceutical active ingredients using electrospinning processes

Electrospinning is an inexpensive and powerful method that employs a polymer solution and strong electric field to produce nanofibers. These can be applied in diverse biological and medical applications. Due to their large surface area, controllable surface functionalization and properties, and typically high biocompatibility electrospun nanofibers are recognized as promising materials for the manufacturing of drug delivery systems. Electrospinning offers the potential to formulate poorly soluble drugs as amorphous solid dispersions to improve solubility, bioavailability and targeting of drug release. It is also a successful strategy for the encapsulation of nutraceuticals. This review aims to briefly discuss the concept of electrospinning and recent progress in manufacturing electrospun drug delivery systems. It will further consider in detail the encapsulation of nutraceuticals, particularly probiotics

Two-Dimenslonal Analysis of Electrical Breakdown in a Nonuniform Gap Between a Wire and a Plane

Electrical breakdown of a gap between a wire (modeled as a hyperboloid) and a plane has been investigated numerically by solving the two-dimensional form of the diffusion flux equations for the charged particle number densities and Poisson\u27s equation for the self-consistent electric field. Electron impact ionization, thermal ionization, and three-body recombination have been considered as the charged particle production and loss mechanisms. The electrode surfaces are considered to be absorbing and the initial density of the particles is small, but nonzero, A gap length of 0.5 mm is investigated and the gas medium is air or argon at atmospheric pressure. The temporal development of the profiles of ion and electron number densities, potential and electric field, and current growth on both the electrodes are presented when the applied voltage is 1500 and 2500 V for both positive and negative wires. When the wire is negatively biased, the peaks in the radial distribution of both of the charged particle densities near the wire occur off the axis except during the very early part of the breakdown. With positive polarity, the electron density maximum always occurs on the discharge axis, while for ions it moves away from the axis, later in the transient, due to the reverse particle drift in the electric field from the negative polarity case, The discharge spreads farther out into the ambient (almost two times the gap length) when the wire is negatively biased than with positive polarity. The effect of charge separation on the externally applied electric field is significant at voltages 2500 V and higher. Ionization is greater in argon than in air for a fixed potential difference between the electrodes

Effect of Negative Ions on Electrical Breakdown in a Nonuniform Air Gap Between a Wire and a Plane

Electrical breakdown of an axisymmetric, atmospheric pressure air gap between a wire and a plane has been investigated for a gap length of 0.5 mm. 0- and 02- have been identified as the negative ions affecting the discharge development in air, besides electrons and positive ions, and have been included in the electrical breakdown model. Five coupled two-dimensional transient partial differential equations describing the discharge evolution in the air gap have been solved using a finite difference algorithm developed earlier. Temporal development of the charged particle number densities, electrostatic potential, electric field, and current at both the electrodes is presented when the wire is negatively biased at 2500 V. The impact of negative ions on gap breakdown has been assessed by comparing the results of analyses with and without negative ions. It is concluded that the negative ions have negligible effect during the early stages of the discharge development. However, as the discharge evolves, the negative ions cause a net loss of electrons from the discharge. The effect is most pronounced away from the discharge axis, where peaks in the electron density occur as breakdown proceeds. Radial spread of discharge and current growth rate are relatively unaffected by the presence of negative ions, but the magnitude of total current at the electrodes has been found to decrease by a decade when the negative ions are present

Analysis of Legacy System in Software Application Development: A Comparative Survey

Software evolution is one of the challenging issues in today’s business environment. It is necessary for the organizations, which make use of Information, and Communication Technologies will have to align their business processes to compete with global business. The existing large software systems (“legacy” systems) have never been built to cope with the current business requirement for their poor coding, design structures, logic and documentation. Moreover, Legacy applications have various problems such as lack of up to-date documentation, skilled man power, resources of the Legacy applications, and high maintenance costs. Even though the Legacy system is obsolete, it contains detailed business rules and in continuous use, because it satisfies the users' needs and forms the backbone of the information flow of organization. One of the possible solutions is to refactor or modernize those systems into a new platform. It is necessary to analyse the existing legacy system for better understanding the business logic and its functionalities. This paper analyses various techniques proposed for understanding Legacy systems in existence

Studies on the Energy Band Discontinuities in SnS/ZnMgO Thin Film Heterojunction

AbstractTin sulfide (SnS), with a direct energy band gap of 1.3eV and high absorption coefficient >104cm-1 is a promising candidate for application as an absorber material for solar cell fabrication. Although several research groups have fabricated SnS-related solar cells, the reported efficiencies were low (< 3.0%). One of the reasons for this low efficiency is the mismatch at the band edges in the heterojunction. In the present work, SnS films have been synthesized by sulfurization of Sn layers deposited by evaporation and RF sputtering onto SnO2 coated glass. The structural properties of the layers were discussed. All RF sputtered Zn0.8Mg0.2O (ZMO) and ZnO:Ga were coated on SnS as buffer and window layers respectively. The band offsets at the SnO2/SnS and ZMO/SnS heterojunctions were evaluated using X-ray photoelectron spectroscopy measurements. The conduction band (ΔEc) and valence band (ΔEv) discontinuities were determined as approximately 1.0eV and 3.5eV for SnO2/SnS and 0.4eV and 1.7eV for ZMO/SnS junction. The related energy band diagram was constructed and the results discussed

Protective effect of bischalcone derivative in Drosophila melanogaster against electron beam radiation

In this paper the protective effect of (2E, 5E) – 2,5-bis (3-methoxy-4-hydroxybenzylidene) cyclopentanone bischalcone derivative (Curcumin analogue, CA), on electron beam radiation induced oxidative stress in Drosophila melanogaster adult flies. Curcumin (CU) was taken as standard. The CA pre treated and irradiated flies were screened for wing shape abnormalities in F1 and F2 generations. There was considerable decrease in the wing shape abnormality frequency in the case of CA fed irradiated flies compared to control