Design. Fabrication and Characterization of Fiber Optic Sensors for Physical and Chemical Applications

Advent of lasers together with the advancement in fiber optics technology has revolutionized the sensor technology. Advancement in the telemetric applications of optical fiber based measurements is an added bonus. The present thesis describes variety of fiber based sensors using techniques like micro bending, long period grating and evanescent waves. Sensors to measure various physical and chemical parameters are described in this thesis.

Development of optical fiber sensors for selected chemical and physical sensing applications

The objective of the preset work is to develop optical fiber sensors for various physical and chemical parameters. As a part of this we initially investigated trace analysis of silica, ammonia, iron and phosphate in water. For this purpose the author has implemented a dual wavelength probing scheme which has many advantages over conventional evanescent wave sensors. Dual wavelength probing makes the design more reliable and repeatable and this design makes the sensor employable for concentration, chemical content, adulteration level, monitoring and control in industries or any such needy environments. Use of low cost components makes the system cost effective and simple. The Dual wavelength probing scheme is employed for the trace analysis of silica, iron, phosphate, and ammonia in water. Such sensors can be employed for the steam and water quality analysers in power plants. Few samples from a power plant are collected and checked the performance of developed system for practical applications.

Optimization of Process Parameters for the Extraction of Gelatin from the Skin of Freshwater Fish and the Evaluation of Physical anal Chemical Characteristics

Faculty of Marine Sciences,Cochin University of Science and Technology

Highly conductive and transparent ZnO thin film using Chemical Spray Pyrolysis technique: Effect of doping and deposition parameters

In the present work we report the preparation details studies on ZnO thin films. ZnO thin films are prepared using cost effective deposition technique viz., Chemical Spray Pyrolysis (CSP). The method is very effective for large area preparation of the ZnO thin film. A new post-deposition process could also be developed to avoid the adsorption of oxygen that usually occurs after the spraying process i.e., while cooling. Studies were done by changing the various deposition parameters for optimizing the properties of ZnO thin film. Moreover, different methods of doping using various elements are also tried to enhance the conductivity and transparency of the film to make these suitable for various optoelectronic applications.

Studies on Modified Atmosphere Packaging of Pearl Spot (Etroplussuratensis) With Special Emphasis to Biochemical and Microbiological Parameters

A modified atmosphere may be defined as a packaging or storage of a perishable product in an atmosphere other than that of air. A modified atmosphere (MA) applies to food packaged products changes continuously throughout the storage period. The pearl spot (Etroplus suratensis) is an important brackish water fish belonging to the family Cichlidae. The present work was carried out to see the effect of modified atmosphere packaging on the shelf life fresh pearl spot stored in ice to extent the shelf life. The objectives of the present study are to study the suitability of Thermoformed Trays for modified atmosphere packaging, to standardize the most suitable gas mixture for modified atmosphere packaging pearl spot based on sensory evaluation, to find out the effect of modified atmosphere packaging in comparison to air packaging, to study the biochemical, microbiological, sensory and textural characteristics during storage, to study the safety concern regarding the Clostridium botulinum during modified atmosphere packaging, to find out the most suitable chemical quality indices for modified atmosphere stored pearl spot

Physical and optical properties of phthalocyanine doped inorganic glasses

Physical and optical properties of various free base and metallic phthalocyanine (Pc) doped glass matrix are reported for the first time. Absorption spectral measurements of H2Pc, MnPc, NiPc, CoPc, CuPc, MoOPc, ZnPc and FePc doped borate glass matrix have been made in the 200–1100 nm region and the spectra obtained are analyzed in the 2.1–6.2 eV region to obtain the optical band gap (Eg) and the width of the band tail (Et). Other important optical and physical parameters viz. refractive index (n), molar extinction coefficient ("), density (½), glass transition temperature (Tg), molecular concentration (N ), polaron radius (rp), intermolecular separation (R), molar refractivity (Rm) are also reported

Physical and optical properties of phthalocyanine doped inorganic glasses

Physical and optical properties of various free base and metallic phthalocyanine (Pc) doped glass matrix are reported for the first time. Absorption spectral measurements of H2Pc, MnPc, NiPc, CoPc, CuPc, MoOPc, ZnPc and FePc doped borate glass matrix have been made in the 200–1100 nm region and the spectra obtained are analyzed in the 2.1–6.2 eV region to obtain the optical band gap (Eg) and the width of the band tail (Et). Other important optical and physical parameters viz. refractive index (n), molar extinction coefficient ("), density (½), glass transition temperature (Tg), molecular concentration (N ), polaron radius (rp), intermolecular separation (R), molar refractivity (Rm) are also reported.

Physical and optical properties of phthalocyanine doped inorganic glasses

Physical and optical properties of various free base and metallic phthalocyanine (Pc) doped glass matrix are reported for the first time. Absorption spectral measurements of H2Pc, MnPc, NiPc, CoPc, CuPc, MoOPc, ZnPc and FePc doped borate glass matrix have been made in the 200–1100 nm region and the spectra obtained are analyzed in the 2.1–6.2 eV region to obtain the optical band gap (Eg) and the width of the band tail (Et). Other important optical and physical parameters viz. refractive index (n), molar extinction coefficient ("), density (½), glass transition temperature (Tg), molecular concentration (N ), polaron radius (rp), intermolecular separation (R), molar refractivity (Rm) are also reported.

Studies on Laser Induced and RF Sputtered Plasma using Optical Emission Spectroscopy and Langmuir Probe

The main objective of the present study is to understand different mechanisms involved in the production and evolution of plasma by the pulsed laser ablation and radio frequency magnetron sputtering. These two methods are of particular interest, as these are well accomplished methods used for surface coatings, nanostructure fabrications and other thin film devices fabrications. Material science researchers all over the world are involved in the development of devices based on transparent conducting oxide (TCO) thin films. Our laboratory has been involved in the development of TCO devices like thin film diodes using zinc oxide (ZnO) and zinc magnesium oxide (ZnMgO), thin film transistors (TFT's) using zinc indium oxide and zinc indium tin oxide, and some electroluminescent (EL) devices by pulsed laser ablation and RF magnetron sputtering.In contrast to the extensive literature relating to pure ZnO and other thin films produced by various deposition techniques, there appears to have been relatively little effort directed towards the characterization of plasmas from which such films are produced. The knowledge of plasma dynamics corresponding to the variations in the input parameters of ablation and sputtering, with the kind of laser/magnetron used for the generation of plasma, is limited. To improve the quality of the deposited films for desired application, a sound understanding of the plume dynamics, physical and chemical properties of the species in the plume is required. Generally, there is a correlation between the plume dynamics and the structural properties of the films deposited. Thus the study of the characteristics of the plume contributes to a better understanding and control of the deposition process itself. The hydrodynamic expansion of the plume, the composition, and SIze distribution of clusters depend not only on initial conditions of plasma production but also on the ambient gas composition and pressure. The growth and deposition of the films are detennined by the thermodynamic parameters of the target material and initial conditions such as electron temperature and density of the plasma.For optimizing the deposition parameters of various films (stoichiometric or otherwise), in-situ or ex-situ monitoring of plasma plume dynamics become necessary for the purpose of repeatability and reliability. With this in mind, the plume dynamics and compositions of laser ablated and RF magnetron sputtered zinc oxide plasmas have been investigated. The plasmas studied were produced at conditions employed typically for the deposition of ZnO films by both methods. Apart from this two component ZnO plasma, a multi-component material (lead zirconium titanate) was ablated and plasma was characterized.

Photometric and fundamental plane studies of galaxies

Determining the morphological parameters that describe galaxies has always been a challenging task. The studies on the correlations between different photometric as well as spectroscopic parameters of the galaxies help in understanding their structure, properties of the stars and gas which constitute the galaxy, the various physical and chemical processes which determine the properties, and galaxy formation and evolution. In the last few decades, the advent of Charge Coupled Devices (CCDs) and near infrared arrays ha\·e provided quick and reliable digitized data acquisition, in the optical and near infrared bands. This has provided an avalanche of data, which can be processed using sophisticated image analysis techniques to obtain information about the morphology of galaxies. The photometric analysis performed in this thesis involve the extraction of structural parameters of early type gala.xies imaged in the near infrared K (2.2ttm) band, obtaining correlations between these, parameters and using them to constrain the large scale properties of galaxi,~s.

Studies on Ilmenite of Chavara and Manavalakurichi Deposites, Southwest Coast of India

The present work attempts to trace the variation in the physical and chemical behavior of ilmenite, since its release from country rocks and subsequent transportation to the coast through the progressive weathering environments of laterite, sedimentary rocks, rivers and estuarine systems. Since the hinterland of the study area consists of crystalline and sedimentary rocks and their weathered forms (laterites), the contribution of each lithological system to the beach placer is attempted. The results of the study show that the most magnetic fraction contains more content of altered phases than the relatively unweathered fractions. The fractions separated above 0.35A define a high grade of ilmenite ore enriched in Ti content. The lattice volume generally decreases with alteration. The magnetic studies revels that the Chavara ilmenite are found to be made up to low magnetic crops with about 46% of the bulk ilmenite constituted by fractions separated at above 0.35A. In the Manavalakurichi ilmenite on the other hand, around 91% of the beach ilmenite is made of fractions separated at or below 0.3A

Effect Insulin on DNA Synthesis and Kinetic Parameters of Thymidine Kinase During Liver Regenaration

The effect of insulin on cell proliferation in vivo has been studied in hepatectomised streptozotocin- diabetic rats. The extent of cell proliferation in sham and hepatectomized- control, diabetic and insulin treated rats were monitored by determining DNA content and [3H]thymidine incorporation into DNA. The kinetic parameters of thymidine kinase a regulatory enzyme for DNA synthesis was also studied in these groups. The rate of DNA synthesis in liver of streptozotocin -diabetic rats was significantly higher 24 hrs post-hepatectomy compared to control and insulin treated diabetic groups. Kinetic studies of thymidine kinase revealed that there was no change in the Michaelis -Menten constant (Km) whereas maximum velocity (Vmax) was elevated in the diabetic hepatectomized groups compared to control and insulin treated hepatectomized groups. Thus our study elucidates the role of insulin in thymidine kinase activity and DNA synthesis.

Elastic Constants And Structural Parameters Of Selected Polycrystalline Ceramics By Ultrasonic Technique

The present work is an attempt to probe the elastic properties in some dielectric ceramics, by using ultrasonic pulse echo overlap technique. The base Ba6-xSm8+2xTi18O54 and Ca5Nb2TiO12 are very important dielectrics ceramics used for microwave communication as well as for substrate materials. Ultrasonic is one of the most widely used and powerful techniques to measure elastic properties of solids. The ultrasonic technique is nondestructive in nature and the measurements are relatively straightforward to perform. One unique advantantage of the ultrasonic technique is that both static and dynamic properties can be measured simultaneously. The velocity and attenuation coefficients of the ultrasonic waves propagating through a medium are related to the microscopic structure of the material and they provide valuable information about the structural changes in the system. Among the various ultrasonic techniques, the pulse echo overlap method is the most accurate and precise one. In the present case the decreased elastic properties of Cas-XMg,Nb2TiO12 and Cas-,ZnNb2TiO12 ceramics can be attributed to their mixture phases beyond x = 1. Moreover, the abrupt change in elastic properties observed for x >1 can also be correlated to the structural transformation of the materials from their phase pure form to mixture phases for higher extent of substitution of the concerned material . Ca4(ANb2Ti)012 (A = Mg, Zn) is the strongest compound with the maximum values for elastic properties . This could be due to the possible substitution of Mg/Zn ions with lesser radius [25] than Ca2+ in perovskite B-site of Ca(Cali4Nb2i4Tili4) O3 material to contribute more ordering and symmetry to the system [20]. All other compositions (x > 1) contain mixed-phases and for such mixed-phase samples, the mechanical properties are difficult to explain.

Surface properties and catalytic activity of vanadia supported on rare earth oxides

An investigation on the physical and chemical characterisation of rare earth oxide supported vanadia is attempted in the present study. La2O3, Sm2O3 and DY2O3 serve the purpose of supports. Supported catalysts were prepared and characterised using various physico chemical techniques. A detailed investigation of acid base properties is also carried out. The nature of interaction of vanadia with lanthanide oxide is discussed and the effect of vanadia loading on the activity of the systems towards reactions of industrial importance is explored.