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.

Nanostructured conducting polymer provides higher surface area for analyte vapor sensing. This investigation aims to synthesize rod-like polypyrrole (PPY) silver nanocomposite tailored by sodium cholate surfactant as soft template for sensing of acetone vapor. During oxidative polymerization of pyrrole by ferric chloride Ag nanoparticle gets deposited on PPY by simultaneous reduction of silver nitrate. The crystal structure, surface morphology and nature of interfacial interactions between the two components of the prepared PPY-silver nanocomposite (PPY-Ag) are analyzed by standard characterization techniques. The Ag nanoparticles deposition on rod-like PPY increases with increasing silver nitrate concentration up to an optimum level. The PPY-Ag nanocomposites show chemiresistive type dynamic sensing responses toward methanol, ethanol and acetone vapor in a mixture with air. A comparative evaluation of typical vapor sensing parameters (% response, response time, recovery time, reproducibility, and selectivity) of PPY-Ag nanocomposite sensor obtained for different volatile organic compounds with those of the pristine PPY sensor is reported. Interestingly, the rod-like PPY-Ag nanocomposite is found to selectively sense acetone vapor showing better % response than that of the other analytes, viz., methanol, ethanol, propanol, water vapor and formaldehyde. The differences in their responses for the different analytes and the selectivity toward acetone vapor are established by considering the difference in their interactions with the nanocomposite.

Synthesis of sodium cholate mediated rod-like polypyrrole-silver nanocomposite for selective sensing of acetone vapor

Two significant propagation characteristics of Ku-band satellite signal, namely rain attenuation and depolarization have been studied over Kolkata (22°34'N, 88°29'E), a tropical location. The existing Simple Attenuation Model (SAM) for rain attenuation estimation has been improved by incorporating the effective rain rate at different rain rates. The impact of rain drop size distribution (DSD) on determining the extent of depolarization at the tropical location is investigated. The lognormal distribution has been found to be more accurate than the gamma distribution to model rain drop sizes in the present case. Rain DSD varies for different types of rain, even during different phases of rain event and is found to influence the cross-polar enhancement of Ku-band signal. The annual variation of cross-polar enhancement indicates the dominance of different types of rain during different seasons of the year.

http://nopr.niscair.res.in/bitstream/123456789/14755/1/IJRSP%2041%284%29%20481-487.pdf

Some characteristics of earth-space path propagation phenomena at a tropical location

Solar control on the cloud liquid water content and integrated water vapor associated with monsoon rainfall over India

Vertical profile of Z-R relationship and its seasonal variation at a tropical location

In this letter, the tropospheric scintillations occurring just before rain commencement have been investigated. This letter indicates the association of the prerain scintillations with both the cloud thickness and the prevailing convection. The convective available potential energy has been considered as a parameter indicating the strength of the associated convection.

Arpita Adhikari

Papers

Synthesis of sodium cholate mediated rod-like polypyrrole-silver nanocomposite for selective sensing of acetone vapor

Some characteristics of earth-space path propagation phenomena at a tropical location

Solar control on the cloud liquid water content and integrated water vapor associated with monsoon rainfall over India

Vertical profile of Z-R relationship and its seasonal variation at a tropical location

Prerain Scintillations of Ku-Band Satellite Signal in Relation to Cloud and Convective Parameters at a Tropical Location