Papers by Author: A. Sarkar

Abstract: In the present work, samples were prepared allowing yeast to grow simply on YPDA-agar medium at a particular incubation temperature using streaking procedure. Doped specimens of yeast were prepared using YPDA-agar medium in presence of ZnO and TiO₂ nanoparticles in a nutrient medium for yeast. ZnO and TiO₂ nanoparticles for delivery over yeast cell were prepared with Gum Arabica and Ethanol (CH₃CH₂OH) respectively as capping agent. Specimens were also developed by laser irradiation on the ZnO doped nanoclusters and pure yeast. FTIR spectroscopy was employed to investigate the effects of nanoclusters and laser irradiation over yeast cell under different conditions. Application of laser irradiation exhibits some positive effect on pure yeast. Effect of ZnO and TiO₂ nanocluster doping on yeast are found to be toxic over Yeast Amide in general. Laser irradiation on nanocluster doped yeast cell enhanced the toxicity of nanoclusters. The later part of this study confirms the destruction of Amides in yeast. This preliminary work is an in-vivo application of drug delivery principle using ZnO nanocluster in Gum Arabica background.

Abstract: Pearl is a bio-originated valuable natural gem and it is also cultivated or harvested for jewellery. In this paper, the material aspects of pearl have been investigated experimentally and it has been found that it has a very high static dielectric constant ~ 105. The functional nature of the material is also established in this work. The beautiful lustre of natural pearl is explained by nano-optics and the layered structure of the material. The origin of super-dielectric nature of pearl has been explained by lightning rod effect (LRE) that causes ultra-high polarization of the dielectric background. The LRE is due to the presence of very small sized nano-particles in the natural pearl. Its electrical conductivity is mostly ionic, only less than 10% of the total conductivity is electronic. The scope of tailoring of its electro-activity has been probed.

Abstract: Gum Arabica, an Electro-Active Bio-Polymer (EABP) is employed to develop photosensitive bio-complexes with chromophore matter collected from natural flowers and chlorophyll from plant leaves. The photosensitivity and enhancement of electro-activity of the developed complex and nano-cluster doped specimens of the same are examined experimentally. The electrical, optical, and photoelectrical characteristics are also investigated experimentally. It has been observed that the electrical property is mostly mixed conducting and can be tailored. The photo electrical behaviour is found to be fascinating. The developed complex is capable of absorbing light by losing or gaining electrons. The application potential of the developed complex toward light harvesting processes is exploited to develop a non-silicon based solar cell. The electrical characteristics of the developed solar cells are studied. The results obtained are good when compared to those of existing solar cells.

Abstract: A nanocomplex of Chromium oxide nanoparticles with biopolymer matrix of gum Arabica is synthesized by natural self-assembly in chemical sol-gel route. Gum Arabica is chosen as base matrix due to its inherent biodegradable property. Experimental specimen of the said complex is prepared to satisfy near quantum size effect criterion. Due to near quantum size effect and spatial localization of nanoclusters, the developed specimen becomes an ideal 2D quantum well system. The longitudinal electrical conduction of the developed system is studied experimentally. Some of its structural aspects are also investigated to make the study conclusive. The dispersed cluster size is estimated by Transmission Electron Microscope (TEM) and X-ray diffraction (XRD). The results of I-V characteristics at temperatures 253 K show the distinctive features of localized energy levels. The spacing between energy levels near ground state to be comparable to the thermal energy at temperature 253 K for a cluster dimension below 10 nm. In this present study the developed specimens with the mentioned nanoclusters estimated from TEM and XRD as below 10 nm. The overall results are found to be encouraging.