Microrheological Studies of Regenerated Silk Fibroin Solution by Video Microscopy

We have carried out studies on the rheological properties of regenerated silk fibroin (RSF) solution using video microscopy. The degummed silk from the Bombyx mori silkworm was used to prepare RSF solution by dissolving it in calcium nitrate tetrahydrate-methanol solvent. Measurements were carried out by tracking the position of an embedded micron-sized polystyrene bead within the RSF solution through video imaging. The time dependent mean squared displacement (MSD) of the bead in solution and hence, the complex shear modulus of this solution was calculated from the bead's position information. An optical tweezer was used to transport and locate the bead at any desired site within the micro-volume of the sample, to facilitate the subsequent free-bead video analysis. We present here the results of rheological measurements of the silk polymer network in solution over a frequency range, whose upper limit is the frame capture rate of our camera, at full resolution. By examining the distribution of MSD of beads at different locations within the sample volume, we demonstrate that this probe technique enables us to detect local inhomogeneties at micrometer length scales, not detectable either by a rheometer or from diffusing wave spectroscopy.Comment: 5 page

Observations on the egg-cases of some ovo-viviparous and viviparous elasmobranchs, with a note on the formation of the elasmobranch egg-case

Egg-cases of a number of oviparous Elasmobranchs have been described from time to time, the oblong egg-capsules of skates and rays being known as `skate barrows,' 'sailors' purses,' 'mermaids' purses,' and 'mermaids' pin-boxes'. As in all the oviparous species known so far, so also in all ovo-viviparous and most of the viviparous species, the egg is protected by an egg-case. But little attention seems to have been paid to the study of the egg-cases of ovoviviparous and viviparous Elasmobranchs

Aquaculture

Aquaculture or aquiculture, as the term denotes, covers the broad aspect of growing organisms under human control in an aquatic environment including all types of water bodies from fresh to saltwater and even brine-pools. Until recently culture of organisms in the brine environment was considered to be more of an academic exercise than of any practical utility. But of late considerable advancements have been made in this direction and such culture operations have come to be known by a separate term-mariculture

Reproduction in Clevelandia ios (Jordan and Gilbert), with an account of the embryonic and larval development

The paper deals with the size at first maturity, breeding habits and sexual dimorphism, embryonic developmont and larval stages of the goby, Olevelandia ios. It was noticed that 23 per cent of females start maturing at a standard length of 29 .0 mm. The percentage increases gradually

Study on primary production and its importance in an integrated fisheries research programme

The importance of the ocean as a source of cheap protein food is too well-known to be emphasised. In recent years there has been a tremendous increase in the fishing activity in all maritime nations and during the last few years the total world production has markedly grown. This study explains the importance of a planned exploitation according to scientific principles to preserve the availability and natural fluctuations in the abundance of stocks of marine fish and other commercially important organisms

Organic production in Indian waters

Studies on the quantitative and qualitative distribution of the standing crop of plankton in the Indian coastal waters have been fairly extensive. But investigations on the production of organic matter which enable us to assess the relative fertility of the various regions of the sea are of recent development. Systematic measurements on the production of matter in the southeast coast of India and recent measurements from the west coast together with the information already available on the nutrient salts enable us to draw a general picture of the productivity of the Indian waters

Into the blue seas

Hunger, starvation, malnutrition and similar depressing terms are often associated with under-developed or developing countries. Fortunately, we in India have not had in recent years any large scale starvation - thanks to the Green Revolution

Fishes and their environment

The concept of environment, so necessary in all fishery biological investigations, is well recognized. Marine biological and oceanographic investigations have yielded very interesting information on the relationship between the forms of organisms, their structures and modes of life and many factors in their milieu

Scientific survey of fishing banks

The need for increased exploitation of our marine resources has been keenly felt and the recent achievements of the power fishing vessels operating off Bombay and Bengal have proved that there is sufficient scope for increased exploitatio

Geographic and climatic features of India and the hydrology of the surrounding seas

The peninsula of India can be divided into three distinct segments: (1) tbe great alluvial plains of North India, (2) the peninsula of Deccan, south of the Vindhya mountains and (3) the great mountain barrier which surrounds the plains to the West, North and East, known as the extra peninsula . Climatically India presents as great contrasts as any area of similar size. In the north-west lies the Rajaputana desert with an average annual rainfall of less than 5 inches and at the NorthEeast in Assam is Chirrapunji with an average of about 430 inches