Dewetting of thin polymer films: Influence of interface evolution

The dewetting dynamics of ultrathin polymer films, e.g. in the model system of polystyrene on a polydimethylsiloxane-covered substrate, exhibits interesting behavior like a fast decay of the dewetting velocity and a maximum in the width of the built-up rim in the course of time. These features have been recently ascribed to the relaxation of residual stresses in the film that stem from the nonequilibrium preparation of the samples. Recent experiments by Coppee et al. on PS with low molecular weight, where such stresses could not be evidenced, showed however similar behavior. By scaling arguments and numerical solution of a thin film viscoelastic model we show that the maximum in the width of the rim can be caused by a temporal evolution of the friction coefficient (or equivalently of the slip length), for which we discuss two possible mechanisms. In addition, the maximum in the width is affected by the sample age. As a consequence, knowing the temporal behavior of friction (or slip length) in principle allows to measure the aging dynamics of a polymer-polymer interface by simple dewetting experiments.Comment: 6 pages, 2 figure

Checklist of marine bivalves and gastropods off Kollam, Kerala

Species diversity of any region can be illustrated by means of an available checklist. It provides an overview of the species that have been recorded. and can be considered to understand the local fauna. Fortnightly surveys were carried out to collect the shell-molluscs samples during 2012 - 2014 period from the by-catch of shrimp/fish trawlers landed at Sakthikulangara-Neendakara Fishing Harbour, Kollam. Collected bivalves and gastropods included both empty shells and living animals. Collected shells were brought to the laboratory and placed in freezer for 24 hours. This would liquefy the mollusc body and allowed easy extraction with a strong jet of water

Rare observation of scar-bearing cuttlebone in a wild-caught Sepia pharaonis (Cephalopoda: Sepiidae) from southeastern Arabian Sea

A rare observation of the severely fractured cum healing cuttlebone of wild-caught Sepia pharaonis is reported and discussed here. The observation showed that cuttlebone of one specimen was severely affected by scars. Scars were interpreted as oval-shaped teeth marks on the dorsal side having a diameter of 23 mm. Several other teeth marks (3-4 numbers) were also observed at the anterodorsal region. Fracture was completely healed at the dorsal side while fracture (19 mm length) was notable in posteroventral region. Inverted ‘V’shaped blackline was also observed on the posteroventral region. However, scar-bearing cuttlebones was more or less symmetrical with respect to the sagittal plane

Mussel Culture

Mariculture of bivalves greater importance in meeting the increasing protein demands of the human population. Bivalve groups such as oyster, mussel and clam are the most important cultivable organisms all over the world. Of these, P. viridis andP.indica forms the most dominant cultivable species. The Central Marine Fisheries Research Institute (CMFRI) has developed eco-friendly techniques for mussel culture. Recently, CMFRI has taken up efforts to popularize mussel culture in all coastal districts of Kerala

Oyster Farming Techniques

Oysters, mussels, clams, scallops, cockles and abalones are major groups of molluscs which are cultured in different parts of the world. Edible oysters are the most important among them, as they are great delicacy and there is growing demand. There is an increasing interest in oyster culture in tropical countries in recent years. In India there is a growing demand for oyster meat in some parts of the country. They are highly esteemed sea food and considered a delicacy in USA, Europe, Japan etc. It is said that ‘oyster’ is scientifically the best known marine animal. It is one of the most widely cultivated species. As early as the first century BC the Romans were the first to develop simple methods of collecting oyster seeds and growing them for food

Rare occurrence of Reinhardt’s cranch squid Liocranchia reinhardti (Cephalopod: Cranchiidae) from southeastern Arabian Sea

Single individual of the rare cranchiid squid Liocranchia reinhardti belonging to the Cranchiidae family was caught in a bottom trawl operated at 80 m in southeastern Arabian Sea. The morphometric measurements and indices of the specimen are provided. Statolith microstructure analysis revealed that the L. reinhardti with 118 mm dorsal mantle length (DML) had an age of 71 days with growth rate of 1.66 mm DML/day

खाद्य शुक्तियाँ - स्वास्थ्य हित और पालन की बुनियादी बातें

खाद्य शुक्तियाँ - स्वास्थ्य हित और पालन की बुनियादी बाते

Unusual fishery of black clam near Aluva sand banks after the floods

In August 2018, severe flood affected in the state of Kerala due to unusual high rainfall. The black clam, Villorita cyprinoides, is found in the backwaters of Kerala, mainly in Vembanad backwaters which support annual average fishery of about 40,000 tonnes. Immediately after the floods, unusual fishery of V. cyprinoides was noticed in the Aluva river as the water level receded after the flood, and it was very easily handpicked by the diving fishermen. This fishery lasted for almost 1 month after the flood and was supported by large sized clams which fetched an average market price `100 to 150 per kg of meat