Studies on Reproductive Biology euui Mass Larval Rearing of Selected Species of Macrobrach

In India scientific commercial farming of Macrobrachium is yet to get a start, the major constraint being the lack of seed. Seed collection from the natural sources alone may not be sufficient, and in such cases seed production in hatcheries is inevitable. This necessitates knowledge of the reproductive biology of the species technology development for brood stock and larval rearing, and the optimum conditions required for larval development to undertake large scale seed production.The present study was taken up with the major objectives of developing a proper, simple and feasible technology for the larval rearing of Macrobrachium, with special emphasis on. mass larval rearing suitable for commercial level operations.

Studies on the meteriological aspects of air pollution over Cochin

Pollutants that once enter into the earth’s atmosphere become part of the atmosphere and hence their dispersion, dilution, direction of transportation etc. are governed by the meteorological conditions. The thesis deals with the study of the atmospheric dispersion capacity, wind climatology, atmospheric stability, pollutant distribution by means of a model and the suggestions for a comprehensive planning for the industrially developing city, Cochin. The definition, sources, types and effects of air pollution have been dealt with briefly. The influence of various meteorological parameters such as vector wind, temperature and its vertical structure and atmospheric stability in relation to pollutant dispersal have been studied. The importance of inversions, mixing heights, ventilation coefficients were brought out. The spatial variation of mixing heights studies for the first time on a microscale region, serves to delineate the regions of good and poor dispersal capacity. A study of wind direction fluctuation, σθ and its relation to stability and mixing heights were shown to be much useful. It was shown that there is a necessity to look into the method of σθ computation. The development of Gausssian Plume Model along with the application for multiple sources was presented. The pollutant chosen was sulphur dioxide and industrial sources alone were considered. The percentage frequency of occurrence of inversions and isothermals are found to be low in all months during the year. The spatial variation of mixing heights revealed that a single mixing height cannot be taken as a representative for the whole city have low mixing heights and monsoonal months showed lowest mixing heights. The study of ventilation co-efficients showed values less than the required optimum value 6000m2/5. However, the low values may be due to the consideration of surface wind alone instead of the vertically averaged wind. Relatively more calm conditions and light winds during night and strong winds during day time were observed. During the most of the year westerlies during day time and northeasterlies during night time are the dominant winds. Unstable conditions with high values of σθ during day time and stable conditions with lower values of σθ during night time are the prominent features. Monsoonal months showed neutral stability for most of the time. A study σθ of and Pasquill Stability category has revealed the difficulty in giving a unique value of for each stability category. For the first time regression equations have been developed relating mixing heights and σθ. A closer examination of σθ revealed that half of the range of wind direction fluctuations is to be taken, instead of one by sixth, to compute σθ. The spatial distribution of SO2 showed a more or less uniform distribution with a slight intrusion towards south. Winter months showed low concentrations contrary to the expectations. The variations of the concentration is found to be influenced more by the mixing height and the stack height rather than wind speed. In the densely populated areas the concentration is more than the threshold limit value. However, the values reported appear to be high, because no depletion of the material is assumed through dry or wet depositions and also because of the inclusion of calm conditions with a very light wind speed. A reduction of emission during night time with a consequent rise during day time would bring down the levels of pollution. The probable locations for the new industries could be the extreme southeast parts because the concentration towards the north falls off very quickly resulting low concentrations. In such a case pollutant spread would be towards south and west, thus keeping the city interior relatively free from pollution. A more detailed examination of the pollutant spread by means of models that would take the dry and wet depositions may be necessary. Nevertheless, the present model serves to give the trend of the distribution of pollutant concentration with which one can suggest the optimum locations for the new industries

Curing studies of elastomer blends with special reference to NR/ NBR and NR/BR blends

There are a large number of commercial examples and property advantages of immiscible elastomer blends.73 Blends of natural rubber (NR) and polybutadiene (BR) have shown various advantages including heat stability, improved elasticity and abrasion resistance. Ethylene-propylene-diene-rubber (EPDM) blended with styrene-butadiene rubber (SBR) has shown improvements in ozone and chemical resistance with better compression set properties. Blends of EPDM and nitrile rubber (NBR) have been cited as a compromise for obtaining moderate oil and ozone resistance with improved low temperature properties. Neoprene (CR)/BR blends offer improved low temperature properties and abrasion resistance with better processing characteristics etc. However, in many of the commercial two-phase elastomer blends, segregation of the crosslinking agents, carbon black or antioxidants preferentially into one phase can result in failure to attain optimum properties. Soluble and insoluble compounding ingredients are found to be preferentially concentrated in one phase. The balance of optimum curing of both phases therefore presents a difficult problem. It has been the aim of this study to improve the performance of commercially important elastomer blends such as natural rubber (NR)/styrene-butadiene rubber (SBR) and natural rubber/polybutadiene rubber (BR) by industrially viable procedures

Quantitative and Qualitative Studies on the Bacteriology of frozen Fishes and Prawns

The thesis is mainly concerned with the study of the bacteriology of freezing of mackerel(Rastrelliger kanaggrta)and prawn (Metgpggaeus ddbsoni) The thesis in four sections describes the salient features of the observations and inferences on the bacteriology of freezing of fishes and prawns. This includes the evaluation of methodology for the optimum recovery of bacteria, bacteriology of the newly caught fish and prawn, the effect of freezing temperatures on the survival of selected species of isolates from fish and prawn and the bacteriology of freezing, frozen storage and thawing of prawn/fish emphasizing the effect contributed by each.

An investigation on the effects of Ag addition in the powder — in tube processing of long multifilamentary (Bi,Pb) - 2223/Ag superconducting tapes

It is important that long superconducting tape must have desired strain tolerance (less reduction of Jc with applied strains) and stress tolerance (less reduction of JC in applied stresses) for its use as coils and magnets. Ag addition to the BPSCCO system has many advantages with its physical and chemical inertness to the system, reduces the processing temperature, and promotes the grain growth, grain alignment and connectivity. All these not only enhance the critical current density of the tapes but also improve the mechanical properties. But the published results show very much scattering on the type of Ag additive to be selected, method of addition and its optimum percentage. Also there are some negative reports in this regard. The present work has been undertaken to study the effect of silver addition in different forms (Ag powder, Ag2O, AgNO3) on the superconducting and mechanical properties of (Bi,Pb)-2223/Ag tapes and to find out a suitable form of Ag additive and its optimum percentage to have better superconducting and mechanical properties. Also it is the aim of the present work is to optimise the process parameters needed to prepare (Bi,Pb)-2223/Ag multifilamentary tapes of length ~ 12 m in solenoid and pancake coil forms with good critical current density and homogeneity of J C along the length of the tapes.

Bioeconomic Evaluation of Semi-intensive Shrimp Farming in Kerala

Penaeid shrimps are, perhaps, the most important fishery resource of the coastal waters of our country. Their exceptionally tasty. protein-rich flesh tops any seafood in foreign exchange earnings. No wonder, the demand of shrimp, the "Pinkish Gold of the Sea" (MPEDA. 1992). is increasing in the world market. The study of the growth of an organism is important in understanding the conditions under which optimum growth occurs. It is also important in getting an insight into the various factors that influence growth. Studies on the growth pattern of commercially important species of shrimp and of the factors that influence their growth rate are essential for the successful cultivation of shrimps.

Hydrometeorological Studies of Kerala state in relation to the Western Ghats

Study of Kerala State in relation to the western Ghats, using The present thesis envisages a hydrometeorological various statistical techniques and the water balance concepts first developed by Thornthwaite. The first chapter of the thesis gives general introduction where the purpose and scope of the study have been given. Chapter II discusses the importance of hydrometeorological studies in general and of water balance in particular, in planning for the overall development of any region. Chapter III consists of the presentation of various geographical features of Kerala. An introduction to the physiography of the western Ghats and detailed hydroclimatic studies of the Western Ghats region which includes analysis of rainfall and the study of water balance elements form Chapter IV. In Chapter V, a detailed hydrometeorological study of Kerala State is made. Discussion of the results of the study and suggestions for optimum utilization of the available water resources for the overall development of the western Ghats region in general and Kerala in particular are made in Chapter VI.

Effective t-J model Hamiltonian parameters of monolayered cuprate superconductors from ab initio electronic structure calculations

The magnetic coupling constant of selected cuprate superconductor parent compounds has been determined by means of embedded cluster model and periodic calculations carried out at the same level of theory. The agreement between both approaches validates the cluster model. This model is subsequently employed in state-of-the-art configuration interaction calculations aimed to obtain accurate values of the magnetic coupling constant and hopping integral for a series of superconducting cuprates. Likewise, a systematic study of the performance of different ab initio explicitly correlated wave function methods and of several density functional approaches is presented. The accurate determination of the parameters of the t-J Hamiltonian has several consequences. First, it suggests that the appearance of high-Tc superconductivity in existing monolayered cuprates occurs with J/t in the 0.20¿0.35 regime. Second, J/t=0.20 is predicted to be the threshold for the existence of superconductivity and, third, a simple and accurate relationship between the critical temperatures at optimum doping and these parameters is found. However, this quantitative electronic structure versus Tc relationship is only found when both J and t are obtained at the most accurate level of theory.

First principles LDA+U and GGA+U study of cerium oxides: Dependence on the effective U-parameter

The electronic structure and properties of cerium oxides (CeO2 and Ce2O3) have been studied in the framework of the LDA+U and GGA(PW91)+U implementations of density functional theory. The dependence of selected observables of these materials on the effective U parameter has been investigated in detail. The examined properties include lattice constants, bulk moduli, density of states, and formation energies of CeO2 and Ce2O3. For CeO2, the LDA+U results are in better agreement with experiment than the GGA+U results whereas for the computationally more demanding Ce2O3 both approaches give comparable accuracy. Furthermore, as expected, Ce2O3 is much more sensitive to the choice of the U value. Generally, the PW91 functional provides an optimal agreement with experiment at lower U energies than LDA does. In order to achieve a balanced description of both kinds of materials, and also of nonstoichiometric CeO2¿x phases, an appropriate choice of U is suggested for LDA+U and GGA+U schemes. Nevertheless, an optimum value appears to be property dependent, especially for Ce2O3. Optimum U values are found to be, in general, larger than values determined previously in a self-consistent way.

Studies on the digestive enzymes of the Indian white prawn Penaeus indicus H. Milne Edwards

The efficiency of a diet not only depends on its nutrient composition and nutrient balance but also on the effective utilization by the animal. In the utilization of dietary nutrients, the digestive enzymes play the crucial role of catalysing the hydrolytic reactions, splitting the macromolecules into simple absorbable molecules. The activity of these biocatalysts is regulated by alterations in pH, temperature, substrate type and concentrations, and also by the presence of activators and inhibitors. Thus any shift from the optimum conditions necessary for these enzymes may affect their activity, thereby correspondingly modify the digestibility of the nutrients supplied to the animals. Thus, investigations on the important digestive enzymes and their preferential conditions of activity are essential, so that the results obtained could be used in rationally adjusting the quality and quantity of feed supplied to the different stages of prawns In India, directed research on nutritional physiology and biochemical approaches to digestion in commercially important prawns is taken up_ only recently, and the field is still in an infant stage. In view of its emerging importance it is identified as an area of priority and the present investigation has been carried out on the Indian white prawn Penaeus indicus

Mineralogical And Sedimentological Studies Of Innershelf And Beach Sediments Along The Coast Between Paravur And Kovalam, South Kerala, India

Continental shelf is of particular significance in marine geology , because it links the two basically different structural zones in the earth's crust; the continents and ocean basins. The shelf area has much wider importance in many fields of activity such as scientific, economic, social, political and strategic. The pace of development has ultimately put pressure on mankind to look for exploitable resources and accessibility to the continental shelf area and beyond. Added to the above, the developmental activities in the coastal area would readily and directly influence the innershelf sediments. This situation demands a thorough geological knowledge of the continental shelf area. Moreover, a successful management of the continental shelf zone requires an optimum data base on the physico-chemical nature of the shelf sediments. Although sedimentological studies were carried out along the western continental shelf of India, a well documented systematic study of the inner shelf off Trivandrum coast is still found to be lacking. Considering the physiographic settings and the vicinity of two renowned placer deposits at Chavara and Manavalakurichi, such a sedimetological inventory has become all the more vital. In view of the above, a research programme has been drawn up to account the salient sedimentological and mineralogical aspects of the innershelf and beach sediments between Paravur and Kovalam, Trivandrum district, Kerala (latitudes 8° 7'00" to 8° 47'45" and longitudes 76°43'00" to 77° 40'45"). The findings are presented in six chapters formatted to address the aim of this research.

“Studies on short polyester fiber - polyurethane elastomer composite with different interfacial bonding agents”

The work presented in this thesis is regarding the development and evaluation of new bonding agents for short polyester fiber - polyurethane elastomer composites. The conventional bonding system based on hexamethylenetetramine, resorcinol and hydrated silica was not effective as a bonding agent for the composite, as the water eliminated during the formation of the RF resin hydrolysed the urethane linkages. Four bonding agents based on MDI/'I‘DI and polypropyleneglycol, propyleneglycol and glycerol were prepared and the composite recipe was optimised with respect to the cure characteristics and mechanical properties. The flow properties, stress relaxation pattern and the thermal degradation characteristics of the composites containing different bonding agents were then studied in detail to evaluate the new bonding systems. The optimum loading of resin was 5 phr and the ratio of the -01 to isocyanate was 1:1. The cure characteristics showed that the optimum combination of cure rate and processability was given by the composite with the resin based on polypropyleneglycol/ glycerol/ 4,4’diphenylmethanediisocynate (PPG/GL/MDI). From the rheological studies of the composites with and without bonding agents it was observed that all the composites showed pseudoplastic nature and the activation energy of flow of the composite was not altered by the presence of bonding agents. Mechanical properties such as tensile strength, modulus, tear resistance and abrasion resistance were improved in the presence of bonding agents and the effect was more pronounced in the case of abrasion resistance. The composites based on MDI/GL showed better initial properties while composites with resins based on MDI/PPG showed better aging resistance. Stress relaxation showed a multistage relaxation behaviour for the composite. Within the-strain levels studied, the initial rate of relaxation was higher and the cross over time was lesser for the composite containing bonding agents. The bonding agent based on MDI/PPG/GL was found to be a better choice for improving stress relaxation characteristics with better interfacial bonding. Thennogravimetirc analysis showed that the presence of fiber and bonding agents improved the thennal stability of the polyurethane elastomer marginally and it was maximum in the case of MDI / GL based bonding agents. The kinetics of degradation was not altered by the presence of bonding agents

Microbial Treatment Of Rubber Latex Centrifugation Effluent

Many of the existing methods for the treatment of rubber latex centrifugation eflluent are not only unsatisfactory in their efliciency to effect near perfect treatment in bringing down the COD to optimum level, but also time consuming and need a large landspace. As the rate of effluent generation is extremely high (20 litres for kilogram of rubber) there is a need for development of efficient system,capable of rapid reduction of COD and BOD. Though the organic load of the rubber efiluent is very high, it does not contain much processed chemicals and therefore it can be considered as a ‘biological eflluent’. Further, the ratio of the Chemical Oxygen Demand to Biological Oxygen Demand (COD/BOD) of this effluent remain almost as a constant value. According to Montgomery (1967), estimation of BOD is not ideally suited for studies on process design, treatability, control of treatment plants, setting standards for treated effluents and assessing the effect of polluting discharges on the oxygen resources of receiving waters. Hence in the present study COD was measured to determine the impact of treatment system on the effluent. In the present study, attempts were made to evaluate the efficiencies of certain methods such as packed bed reactor using immobilized microbial cells, rotating biological contactor (RBC) and activated sludge process, for rapid and efficient treatment of natural rubber latex centrifugation effluent. In addition, studies were also carn'ed out to develop a suitable bioprocess for the coagulation of skim latex, as an alternative to the presently used acid coagulation process towards reducing the pollution load, besides recovering quality rubber

Establishment and characterization of India's first marine fish cell line (SISK) from the kidney of sea bass (Lates calcarifer)

A continuous cell line (SISK) from kidney of sea bass, Lates calcarifer, has been established and characterized. The cell line was maintained in Leibovitz' L-15 supplemented with 15% fetal bovine serum. This cell line has been subcultured more than 100 times over a period of 2 years. The SISK cell line consists of predominantly of epithelial-like cells. These cells showed strong positive for epithelial markers such as cytokeratin 19 and pancytokeratin. The cells were able to grow at temperature between 25 and 32 °C with optimum temperature of 28 °C. The growth rate of sea bass kidney cells increased as the FBS proportion increased from 2% to 20% at 28 °C with optimum growth at the concentrations of 15% or 20% FBS. The distribution of chromosome number was 30 to 56 with a modal peak at 48 chromosomes. Polymerase chain reaction products were obtained from SISK cells and tissues of sea bass with primer sets of microsatellite markers of sea bass. Five fish viruses were tested on this cell line to determine its susceptibility to these viruses and this was found to be susceptible to MABV NC1 and nodavirus, and the infection was confirmed by RT-PCR and CPE. This suggests that the SISK cell line has good potential for the isolation of various fish viruses. This cell line has been shown to be susceptible to bacterial extracellular products. The SISK cell line is the India's first marine fish cell line.

Immunostimulatory effect of a marine yeast Candida sake S165 in Fenneropenaeus indicus

The efficacy of a marine yeast Candida sake as source of immunostimulant to Indian white shrimp Fenneropenaeus indicus was estimated. Biomass of C. sake was prepared using malt extract agar and incorporated at graded levels into a standard diet to prepare yeast diets of varying biomass concentrations (1%, 10% and 20%). F. indicus were fed on these diets for a period of 28 days and challenged orally with white spot syndrome virus (WSSV) and immune parameters such as total haemocyte count, phenoloxidase and nitroblue tetrazolium reduction (NBT) were determined. Ten per cent C. sake in the diet was found to support an optimum immune response in the animals in general and their enhancement could be observed on the second and third day following challenge with the virus. The study has demonstrated that marine yeast C. sake at 10% in diet (w/w) may be used as an effective source of immunostimulants in F. indicus