Birla Institute of Technology, Mesra

About: Birla Institute of Technology, Mesra is a education organization based out in Ranchi, India. It is known for research contribution in the topics: Computer science & Dielectric. The organization has 2801 authors who have published 4789 publications receiving 52426 citations. The organization is also known as: BIT.

Shape and size dependent nonlinear refraction and absorption in citrate-stabilized, near-IR plasmonic silver nanopyramids

Abstract: Using a combination of a mild stabilizer and a mild reductant, sodium citrate and hydrazine hydrate, anisotropic silver nanocrystals (NCs) were synthesized with tunable plasmon peaks at 550 nm, 700 nm, 800 nm, 900 nm and 1010 nm (the samples are named Ag-550, Ag-700, Ag-800, Ag-900 and Ag-1010, respectively). TEM investigations revealed that Ag-550 NCs were pentagonal nanoplates while the other four samples were nanopyramids with a pentagonal base with the edge length varying between 15 and 30 nm. The non-linear optical (NLO) properties of these NCs were studied by the Z-scan technique using the CW He–Ne laser (632.8 nm, 15 mW). The shape change from 2D nanoplates (Ag-550) to 3D nanopyramids (Ag-700) resulted in sign reversal of the non-linear refractive index, n2, from a negative (−3.164 × 10−8 cm2 W−1) to a positive one (1.195 × 10−8 cm2 W−1). This corresponds to a change from a self-defocussing effect to a self-focussing one. Besides shape, the size effect is also prominently observed. Amongst nanopyramids, as the edge length increases, n2 increases linearly and reaches a maximum of 3.124 × 10−8 cm2 W−1. Doubling the edge length from 15 nm to 30 nm resulted in 162% increase in n2. On moving from Ag-550 to Ag-900 NCs, with the increasing plasmon wavelength, the non-linear absorption (NLA) coefficient increased exponentially to a high value of 8.52 × 10−4 cm W−1. However, Ag-1010 showed 29% decrease in NLA which is attributed to twinning present in the crystal structure as seen in the HR-TEM images. Due to the tunable NLO properties, these anisotropic Ag NCs hold great potential for applications in optical limiting, switching and data storage.

Geospatial Approach for Quantitative Drainage Morphometric Analysis of Varuna River Basin, India

Abstract: Abstract An assessment of Varuna river basin of India was performed to study the various drainage parameters in GIS platform. The delineation of drainage network is possible either physically from topographic sheets or with the help data of Digital Elevation Model (DEM) by methods for calculation techniques. Extraction of the basin and sub-basins, stream network has been produced to evaluate the drainage characteristics in the study zone. The entire Varuna river basin has been subdivided into 3 sub-watersheds and 41 morphometric parameters have been computed under four broad categories i.e. drainage network, basin geometry, drainage texture, and relief characteristics. The morphometric analysis has been performed and different parameters have been correlated with each other to understand their underlying connection and their role over the basin hydro geomorphology. The study discloses different types of morphometric analysis and how they influence the soil and topography of the basin. The investigation and estimation of basin morphometry and relief parameters in GIS will be of massive utility in catchment area advancement, understanding the watershed for natural resource evaluation, planning and administration at any scale. The outcomes thus generated equip us with significant knowledge and may also provide an input that are essential in decision making for watershed planning and drainage development of the watershed.

A Novel Polymeric Biomaterial Based on Carboxymethylstarch and its Application in Controlled Drug Release

Abstract: This study reports investigation of the sustained release behavior of a model drug (acetylsalicylic acid) from carboxymethylstarch (CMS) based matrix. CMS was prepared by incorporation of carboxymethyl groups in the starch moiety; by reacting starch with sodium salt of monochloro acetic acid in presence of sodium hydroxide. The in vitro drug release study was performed by United States Pharmacopeia rotating paddle method, at various pH. The rate of drug release from the above matrix was found to increase with increase in pH. Further, the release behavior of the drug from the CMS based matrix was found to be non-Fickian, n value being between 0.80 and 0.85, suggesting that the release was controlled by a combination of tablet erosion and diffusion of the drug from the swollen matrix. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Preparation, characterization and dielectric properties of polyetherimide nanocomposites containing surface-functionalized BaTiO3 nanoparticles

Abstract: Polyetherimide (PEI)/hydroxyl-functionalized barium titanate (BaTiO3) nanocomposite films were successfully prepared through solution-casting followed by subsequent thermal imidization. The results of Fourier transform infrared spectroscopy confirmed that the chemical treatment with hydrogen peroxide (H2O2) could efficiently derive hydroxyl groups on the surface of BaTiO3 nanoparticles. The strong interaction between the hydroxyl-functionalized BaTiO3 and the PEI matrix greatly enhanced the particle dispersion as well as the interfacial adhesion, as evidenced by scanning electron microscopy. The PEI nanocomposite with hydroxyl-functionalized BaTiO3 nanoparticles (50 vol% BaTiO3 loading) showed an increased dielectric permittivity of 52.78 at 1 kHz compared with the dielectric permittivity (33.87) of PEI/raw BaTiO3 composite. The loss tangent was still low (less than 0.03) when the content of hydroxyl-functionalized BaTiO3 was 50 vol%. For PEI/BaTiO3 nanocomposites, the frequency and temperature dependences of the dielectric properties were significantly reduced through functionalizing the surface of BaTiO3 nanoparticles with H2O2. Different theoretical approaches were employed to predict the effective permittivity of the nanocomposite systems and the results are compared with the experimental results. Copyright © 2012 Society of Chemical Industry