The solution of electromagnetic scattering by a homogeneous prolate (or oblate) spheroidal particle with an arbitrary size and refractive index is obtained for any angle of incidence by solving Maxwell's equations under given boundary conditions. The method used is that of separating the vector wave equations in the spheroidal coordinates and expanding them in terms of the spheroidal wavefunctions. The unknown coefficients for the expansion are determined by a system of equations derived from the boundary conditions regarding the continuity of tangential components of the electric and magnetic vectors across the surface of the spheroid. The solutions both in the prolate and oblate spheroidal coordinate systems result in a same form, and the equations for the oblate spheroidal system can be obtained from those for the prolate one by replacing the prolate spheroidal wavefunctions with the oblate ones and vice versa. For an oblique incidence, the polarized incident wave is resolved into two components, the TM mode for which the magnetic vector vibrates perpendicularly to the incident plane and the TE mode for which the electric vector vibrates perpendicularly to this plane. For the incidence along the rotation axis the resultant equations are given in the form similar to the one for a sphere given by the Mie theory. The physical parameters involved are the following five quantities: the size parameter defined by the product of the semifocal distance of the spheroid and the propagation constant of the incident wave, the eccentricity, the refractive index of the spheroid relative to the surrounding medium, the incident angle between the direction of the incident wave and the rotation axis, and the angles that specify the direction of the scattered wave.

Light Scattering by a Spheroidal Particle

This paper presents an overview of the work done on graphene in recent years. It explains the preparation techniques, the properties of graphene related to its physio-chemical structure and some key applications. Graphene, due to its outstanding electrical, mechanical and thermal properties, has been one of the most popular choices to develop the electrodes of a sensor. It has been used in different forms including nanoparticle and oxide forms. Along with the preparation and properties of graphene, the categorization of the applications has been done based on the type of sensors. Comparisons between different research studies for each type have been made to highlight their performances. The challenges faced by the current graphene-based sensors along with some of the probable solutions and their future opportunities are also briefly explained in this paper.

Graphene and its sensor-based applications: A review

Preparation of chitosan-TiO2 composite film with efficient antimicrobial activities under visible light for food packaging applications.

Pectin bionanocomposite films filled with various concentrations of two different types of halloysite nanotubes were prepared and characterized in this study as potential films for food packaging applications. The two types of halloysite nanotubes were long and thin (patch) (200–30 000 nm length) and short and stubby (Matauri Bay) (50–3000 nm length) with different morphological, physical, and dispersibility properties. Both matrix (pectin) and reinforcer (halloysite nanotubes) used in this study are considered as biocompatible, natural, and low-cost materials. Various characterization tests including Fourier transform infrared spectroscopy, field emission scanning electron microscopy, release kinetics, contact angle, and dynamic mechanical analysis were performed to evaluate the performance of the pectin films. Exceptional thermal, tensile, and contact angle properties have been achieved for films reinforced by patch halloysite nanotubes due to the patchy and lengthy nature of these tubes, which form a b...

Effect of Morphology and Size of Halloysite Nanotubes on Functional Pectin Bionanocomposites for Food Packaging Applications.

Pectins functionalized biomaterials; a new viable approach for biomedical applications: A review.

The low-level sensing of ethanol has gained enormous importance due to its application in human health monitoring, road safety, fermentation and food industries. In this investigation, we report the synthesis of ribbonlike nanostructures of polypyrrole (PPY), a conducting polymer, using sodium cholate micelles as a soft template. The PPY nanoribbons were found to exhibit good sensor response along with high degree of selectivity to ethanol vapour as opposed to several common volatile organic compounds (VOCs) showing its suitability as a selective sensing layer to detect ethanol from a mixture containing ethanol, methanol, 2-propanol, toluene, n-hexane, and humidity. The sensing mechanism and its selectivity to ethanol vapor were explained by considering a hydrogen bond type interaction of the OH groups of ethanol molecules with large number of N or NH groups of the PPY available on the surface due to its nanoribbon morphology. Investigation of the cytotoxicity of the PPY nanoribbons revealed good biocompatibility.

Na-cholate micelle mediated synthesis of polypyrrole nanoribbons for ethanol sensing

This paper studies the rain-induced propagation characteristics over a tropical location Kolkata, India, using the data collected over a 7 year period, i.e., 2004–2010. This location experiences substantial rainfall during the Indian Summer Monsoon (ISM) season which is preceded by premonsoon rainfall accompanied by strong convection. Accumulations, event duration, and fade duration statistics are presented. Long-term observations for three propagation effects, namely rain attenuation, scintillations, and depolarization, are analyzed in this paper. The seasonal patterns of these phenomena are examined to reveal the characteristic features of Kolkata. The interrelations among rain rate, rain attenuation, scintillations, and depolarization are also investigated. Propagation detriments for identical rain rates are more severe in premonsoon compared to monsoon period, mainly because of the different microphysical properties of precipitation. However, the percentage occurrences of various propagation effects are higher in monsoon than premonsoon.

Rain and Rain-Induced Degradations of Satellite Links Over a Tropical Location

Rain attenuation studies from radiometric and rain DSD measurements at two tropical locations

The inter-relation of rain drop size distribution with cloud base height has been investigated at a tropical location, Kolkata (22°34′N, 88°22′E). The study focuses the association of rain drop size distribution with cloud base height during the summer monsoon and pre-monsoon. It is observed that the mean diameter of the largest drop increases with the lowering of cloud base height. A notable difference between the pre-monsoon and monsoon rain events have been identified in the inter-relation of rain drop size with cloud base height. Results indicate that the large drops are more frequent in the pre-monsoon season than the monsoon.

Arpita Adhikari

Papers

Na-cholate micelle mediated synthesis of polypyrrole nanoribbons for ethanol sensing

Rain and Rain-Induced Degradations of Satellite Links Over a Tropical Location

Rain attenuation studies from radiometric and rain DSD measurements at two tropical locations

Rain drop size variation with cloud base height at a tropical location

Studies on some characteristics of rain-induced depolarization of Ku- band signal over an earth-space path at a tropical location