Synthesis and Study of Photophysical and Metal Ion Binding Properties of a Few Novel Semisquaraine and Croconaine Dyes

Photosciences & Photonics, Chemical Sciences & Technology Division, National Institute for Interdisciplinary Science & Technology

Dynamics Of Pesticides In The Backwaters Of Kuttanad

The tremendous growth in industrial production and the consequent improving in the standards of living have provoked worldwide discussion on environmental quality. The question of abusive use of pesticides for crop protection and vector control programmes is only one aspect of this entire complex. Inspite of this, tendentious publications such as Rachel Carson’s Silent spring have brought crop protection into the foreground of environmental discussions. The persistence and high stability of organochlorine pesticides are regarded as problematic and the accumulation of pesticides residues and its metabolites in the different compartments of the environment is one of the major concerns. Because of their persistence in the aquatic environment and biomagnifications in food chain, the continuous use of pesticides will have wider implications not only in aquatic environmental quality but also on human health. The residual levels of these persistent chemicals exceed their permissible limits, and get partitioned among the constituent phases of the aquatic systems. Crop protection is only part of the agricultural economy and in agriculture itself has led to the most fundamental changes in the human environment. So, in all areas of life one must weigh the desired advantages against possible disadvantages. The proposed thesis is based on the investigations on the distributions of organochlorine and organophosphorus pesticides in the waters and sediments of Kuttanad backwaters. Kuttanad, a unique agricultural area, which forms the southern part of the Vembanad lake, is a deltaic formation of four river systems entering the southern part of the Cochin estuary. No systematic study has ever been done to assess the ecotoxicological impact of these diverse chemicals and their metabolites in Kuttanad area. So, a detailed systematic and rigorous investigation on the distributions of these persistent chemicals is carried out. The thesis is divided into 7 Chapters

Investigation of structural, optical and electrical properties and valence band splitting in cu-ln-se compounds

Investigations on thin films that started decades back due to scientific curiosity in the properties of a two-dimensional solid, has developed into a leading research field in recent years due to the ever expanding applications of the thin films in the fann of a variety of active and passive microminiaturized components and devices, solar cells, radiation sowces and detectors, magnetic memory devices, interference filters, refection and antireflection coatings etc. [1]. The recent environment and energy resource concerns have aroused an enonnous interest in the study of materials in thin film form suitable for renewable energy sources such as photovoltaic devices. Recognition of the immense potential applications of the chalcopyrites that can fonn homojunctions or heterojunctions for solar cell fabrication has attracted many researchers to extensive and intense research on them. In this thesis, we have started with studies performed on CuInSe, thin films, a technologically well recognized compound belonging to the l•ill-VI family of semiconductors and have riveted on investigations on the preparation and characterization of compoWlds Culn3Se5. Culn5Seg and CuIn7Se12, an interesting group of compounds related to CuInSe2 called Ordered Vacancy Compounds, having promising applications in photovoltaic devices. A pioneering work attempted on preparing and characterizing the compound Culn7Sel2 is detailed in the chapters on OVC's. Investigation on valence band splitting in avc's have also been attempted for the first time and included as the last chapter in the thesis. Some of the salient features of the chalcopyrite c.ompounds are given in the next section .of this introductory chapter.