SIZE-DEPENDENT OPTICAL PROPERTIES OF COPPER NANOPARTICLE OVER A WIDE RANGE OF WAVELENGTHS: AN ELECTROMAGNETIC SIMULATION STUDY

In this article, we modulate the optical absorption, scattering, extinction, transmission and field intensities of an ellipsoid copper nanoparticle by tuning its dimension. The finite-difference time-domain (FDTD) method is employed for this electromagnetic simulation study and a comparative investigation has been carried out. In the investigation it is found that Cu nanoparticle with 20 nm size exhibiting the optical absorption at the resonant wavelength ~530 nm. This plasmon peak is shifted to ~550 nm when the particle size is increased to 40 nm. In addition to shifting, the enhancement of the plasmon peak is also observed. This nonlinear enhancement arises due to the size dependent property of the surface plasmon resonance (SPR). For smaller nanoparticle, the scattering is found to be negligible as compared to the larger particle. The scattering becomes dominant as the particle size increases beyond 28 nm. The scattering cross-sections of all the particle decreases at the longer wavelength. All the structures exhibit a strong transmission minimum at a wavelength close to 590 nm in the visible spectrum. However, above 600 nm high transmission is observed. The electric field intensity is also enhanced from 5.15 (V/m)2 to 16.9 (V/m)2 as the particle size increases from 20 nm to 40 nm. We strongly believe that this research could provide an overall idea about the importance of particle size variation while fabricating Cu based solar energy harvesting systems, plasmonics photovoltaic devices etc

Three-dimensional modified Korteweg-de Vries equation in a magnetised relativistic plasma with positron beam and vortex-like electron distribution

The nonlinear features of Ion Acoustic (IA) waves are studied in a fully relativistic three-dimensional (3-D) plasma system with consideration of effect of both positron beam and trapped electrons. We consider a set of 3-D magnetised hydrodynamic equations with pressure expansion for our plasma model along with kinetic Vlasov equation for electrons. Applying the perturbative expansion technique, a Modified Korteweg-de Vries (m-KdV)-like equation is derived, exhibiting the evolution of small amplitude IA waves in plasma. The modified coefficient of nonlinear term in K-dV equation has arrived due to impact of vortex-like distribution of electrons. An analytical and numerical investigation of the nonlinear evolution equations is exhibited with external magnetic field effects, the time derivative pressure expansion as well as other parameters like relativistic effect, mass variation, beam velocity and temperature effect have been taken into consideration. The presence of vortex like trapped electron distribution and positron beam governs the influence of soliton structure quite significantly. The present result should help us to understand the experiments that involve particle trapping and also the salient features of astrophysical environment like ionospheric plasma together with situations in plasma describing the electrostatic solitary structures usually seen in antimatter-related environment in interplanetary region

Rice Straw Based Evaluation of Lignolytic and Cellulolytic Capabilities of Novel Strains of Saprophytic Fungi from Indo-Burma Biodiversity Hotspot

Superior lignocellulolytic microbes are useful for efficient bioconversion of plant biomass. Eight fungal strains were isolated from compost and forest litter of an Indo-Burma Biodiversity hotspot and were evaluated for their lignolytic and cellulolytic capabilities. X-ray diffraction (XRD) study was performed to test their effect on cellulose crystallinity of rice straw. Scanning electron spectroscopic (SEM) and Fourier transform-infrared (FT-IR) spectroscopic analysis were performed to study the surface morphology and chemical changes occurred in the fungi treated rice straw, respectively. The fungus <i>Fusarium equiseti</i> strain TWRF-10 showed endoglucanase, exoglucanase, and endoxylanase activity of 99.19, 87.39, and 166.81 IU g^–1 rice straw, respectively, whereas <i>Penicillium simplicissimum</i> strain TRF-27 showed laccase and Mn peroxidase activity of 248.53 and 168.5 IU g^–1 rice straw, respectively. The strain TRF-27 caused a 65% reduction in cellulose crystallinity. These strains should be further tested for industrial use