Thermal characterization of intrinsic and extrinsic InP using photoacoustic technique

An open photoacoustic cell operating in the low range of chopping frequency has been employed to evaluate the thermal diffusivity values of intrinsic InP and InP doped with S, Sn and Fe. The experimental set-up is calibrated by the evaluation of thermal diffusivity value of pure Si and GaAs. The present investigation shows that doped samples show a reduced value for thermal diffusivity compared to intrinsic sample. From the analysis of data it is also seen that nature of dopant clearly influences the thermal diffusivity value of semiconductors. The results are explained in terms of phonon assisted heat transfer mechanism in semiconductors

Thermal characterization of intrinsic and extrinsic InP using photoacoustic technique

An open photoacoustic cell operating in the low range of chopping frequency has been employed to evaluate the thermal diffusivity values of intrinsic InP and InP doped with S, Sn and Fe. The experimental set-up is calibrated by the evaluation of thermal diffusivity value of pure Si and GaAs. The present investigation shows that doped samples show a reduced value for thermal diffusivity compared to intrinsic sample. From the analysis of data it is also seen that nature of dopant clearly influences the thermal diffusivity value of semiconductors. The results are explained in terms of phonon assisted heat transfer mechanism in semiconductors

Thermal characterization of intrinsic and extrinsic InP using photoacoustic technique

An open photoacoustic cell operating in the low range of chopping frequency has been employed to evaluate the thermal diffusivity values of intrinsic InP and InP doped with S, Sn and Fe. The experimental set-up is calibrated by the evaluation of thermal diffusivity value of pure Si and GaAs. The present investigation shows that doped samples show a reduced value for thermal diffusivity compared to intrinsic sample. From the analysis of data it is also seen that nature of dopant clearly influences the thermal diffusivity value of semiconductors. The results are explained in terms of phonon assisted heat transfer mechanism in semiconductors

Development of Photorefractive Polymers: Evaluation of Photoconducting and Electro-optic Properties

This Thesis discussed molecules suitable for photorefractive effect. Out of the molecules studied, only one system was used to make photorefractive polymers system. Other molecules, especially, the electro-optic polymer, Poly(3-methacrloyl-1-(4'-nitro-4-azo-1'-phenyl)phenylalanine-co- methyl methacrylate) can be subjected to more detailed studies to explore the possibilities of using them for electro-optic applications. Though not included in the thesis, the efficient photoconductor, Poly(6-tert-butyl-3- phenyl-3,4-dihydro-2H-1,3-benzoxazine) sensitized with C60, which was described in Chapter 3 showed a low magnitude photovoltaic effect. This hints at the possibility of using this system for organic solar cells also. The thesis presented the initial observation of photorefractive effect in a polybenzoxazine based polymer system. A detailed analysis of the effect of C60, ECZ and DR1 can be carried out to check for the possibility of a high efficiency photorefractive system.

Water Quality Management–Application of Flocculants and Algicides

School of Environmental Studies, Cochin University of Science and Technology

Diblock and Triblock Copolymers of Styrene and Acetoxymethylstyrene by One-Pot ATRP

We describe the synthesis of diblock and triblock copolymers by sequential atom transfer radical polymerization of styrene and acetoxymethylstyrene. Contrary to the usual block copolymerization involving isolation of the macroinitiator, a convenient one-pot procedure is developed. This is possible because of the preferential polymerization of acetoxymethylstyrene, even in the presence of residual styrene, as inferred from characterization of the intermediate polystyrenes and the block copolymers by size exclusion chromatography, 1H NMR, Fourier transform infrared spectroscopy, differential scanning calorimetry, and GPEC techniques. The latent acetoxy functionalities in these block copolymers are shown to be easily unmasked to OOH and OBr functionalities, with the potential for block ionomers and dense graft architectures.

An investigation into observational characteristics of rainfall and temperature in Central Northeast India—a historical perspective 1889–2008

Mann–Kendall non-parametric test was employed for observational trend detection of monthly, seasonal and annual precipitation of five meteorological subdivisions of Central Northeast India (CNE India) for different 30-year normal periods (NP) viz. 1889–1918 (NP1), 1919–1948 (NP2), 1949–1978 (NP3) and 1979–2008 (NP4). The trends of maximum and minimum temperatures were also investigated. The slopes of the trend lines were determined using the method of least square linear fitting. An application of Morelet wavelet analysis was done with monthly rainfall during June– September, total rainfall during monsoon season and annual rainfall to know the periodicity and to test the significance of periodicity using the power spectrum method. The inferences figure out from the analyses will be helpful to the policy managers, planners and agricultural scientists to work out irrigation and water management options under various possible climatic eventualities for the region. The long-term (1889–2008) mean annual rainfall of CNE India is 1,195.1 mm with a standard deviation of 134.1 mm and coefficient of variation of 11%. There is a significant decreasing trend of 4.6 mm/year for Jharkhand and 3.2 mm/day for CNE India. Since rice crop is the important kharif crop (May– October) in this region, the decreasing trend of rainfall during themonth of July may delay/affect the transplanting/vegetative phase of the crop, and assured irrigation is very much needed to tackle the drought situation. During themonth of December, all the meteorological subdivisions except Jharkhand show a significant decreasing trend of rainfall during recent normal period NP4. The decrease of rainfall during December may hamper sowing of wheat, which is the important rabi crop (November–March) in most parts of this region. Maximum temperature shows significant rising trend of 0.008°C/year (at 0.01 level) during monsoon season and 0.014°C/year (at 0.01 level) during post-monsoon season during the period 1914– 2003. The annual maximum temperature also shows significant increasing trend of 0.008°C/year (at 0.01 level) during the same period. Minimum temperature shows significant rising trend of 0.012°C/year (at 0.01 level) during postmonsoon season and significant falling trend of 0.002°C/year (at 0.05 level) during monsoon season. A significant 4– 8 years peak periodicity band has been noticed during September over Western UP, and 30–34 years periodicity has been observed during July over Bihar subdivision. However, as far as CNE India is concerned, no significant periodicity has been noticed in any of the time series.

Optimization of carbon and nitrogen sources and growth factors for the production of an aquaculture probiotic (Pseudomonas MCCB 103) using response surface methodology

Aim: To develop a new medium for enhanced production of biomass of an aquaculture probiotic Pseudomonas MCCB 103 and its antagonistic phenazine compound, pyocyanin. Methods and Results: Carbon and nitrogen sources and growth factors, such as amino acids and vitamins, were screened initially in a mineral medium for the biomass and antagonistic compound of Pseudomonas MCCB 103. The selected ingredients were further optimized using a full-factorial central composite design of the response surface methodology. The medium optimized as per the model for biomass contained mannitol (20 g l)1), glycerol (20 g l)1), sodium chloride (5 g l)1), urea (3Æ3 g l)1) and mineral salts solution (20 ml l)1), and the one optimized for the antagonistic compound contained mannitol (2 g l)1), glycerol (20 g l)1), sodium chloride (5Æ1 g l)1), urea (3Æ6 g l)1) and mineral salts solution (20 ml l)1). Subsequently, the model was validated experimentally with a biomass increase by 19% and fivefold increase of the antagonistic compound. Conclusion: Significant increase in the biomass and antagonistic compound production could be obtained in the new media. Significance and Impact of the Study: Media formulation and optimization are the primary steps involved in bioprocess technology, an attempt not made so far in the production of aquaculture probiotics.

Electrophoretic, Biochemical and Morphometric studies on Three Bivalves of Cochin and Nearby Waters

Division of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology

Semiconductor Oxides Mediated Photocatalytic Removal of Chemical and Bacterial Pollutants from Wastewater

School of Environmental Studies, Cochin University of Science and Technology

Brain Cholinergic and Dopaminergic Functions in Streptozotocin Induced Diabetic Rats: Effects of Curcumin and Vitamin D3 Supplementation

Department of Biotechnology, Cochin University of Science and Technology