Systematics, biology, ecology And zoogeography of holothurians: Some observations on the biology of the holothurian Holothuria (metriatyla) scabra (Jaeger)

Some aspects on the biology of commercially most important holothuriam Holothuria (Metriatyla) acabra are presented. It subsists on the organic matter present in the mud or sand. An analysis of gut content revealed fine mud (75-125 ^), sand particles (250-500 p.), moUuscan shells, debris and bits of algae. This species spawns in June and October. By external examination and by taking sections of the gonads, five maturity stages such as immature, maturing, early mature, late mature and spent have been fixed. The characteristics of different stages of maturity are presented in detail

Studies on the Biology, Ecology and Fishery of the sea cucumber Holothuria (Metriatyla) scabra (Jaeger) from southeast coast of India, embodies

Among the echinoderms, holothurians are commercially imnortant. Certain species of holothurians are processed and the processed material is known as Beche-de-mer or Trepang in trade parlance. Beche-de-mer is considered a Chinese delicacy. At present, Indie is earning a foreign exchange of more than one crore rupees by exporting Beche-de-mer . This product has no internal market. It has been introduced by the Chinese and is in existence in the Gulf of Manner and Palk Bay for more than one thousand years. It has high nutritive value and also considered to have certain medicinal properties. The main international markets are Hongkong, Singapore and Malaysia

Kinetics of nitrogen in sodic soil of Kumulur village, Trichy District, Tamil Nadu under different organic and inorganic amendments

Currently more than 20 per cent of the world’s irrigated land is salt affected. Of that about 60 per cent are sodic soils, warranting greater attention for efficient and eco-friendly environmentally amelioration techniques. Transformation and availability of several plant nutrient elements are affected by soil sodicity. Alkali/sodic soils are to be reclaimed so as tomake nutrients available to plants optimally. A laboratory incubation study was examined to analyse the impact of various amendments, either alone or in combination with nitrogen (N) @75 kg/ha, on the physico-chemical characteristics and nitrogen dynamics in sodic soil of Kumulur village Trichy District, Tamil Nadu (pH-10.4, EC-0.40 dS, m-1, ESP-31.8). The investigation was conducted at ADAC&RI in Trichy with three replications and eight treatments in a completely randomized design. The treatments used for sodic soil reclamation utilizing a standardized procedure were Gypsum (GYP) + Green manure (GM) @ 6.5 t ha-1 (T2), Distillery spent wash (DSW) @ 5 lakhs liter-1(T4), and Green leaf manure (GLM) @ 12.5 t ha-1(T3). Soil samples were taken at 15-day intervals from the 15th to the 60th day and tested for NH4-N, NO3-N, and accessible nitrogen. Using DSW, GYP + GM, and GLM, the pH of the water was decreased from 10.2 to 8.37, 8.42, and 9.21, respectively. The soil pH dropped the most in the DSW-controlled treatments. The application of nitrogen alone without any amendments (T5) recorded a higher value (135 kg ha-1) during an initial period (15 days) only and thereafter declined sharply due to various losses, i.e., volatilization, denitrification or fixation. When nitrogen was applied along with amendments, a significant (CD-0.05%) buildup in available N contents was observed over the application of N alone. Available nitrogen (325 kg ha-1), nitrate nitrogen (102 kg ha-1) and ammonical nitrogen (205 kg ha-1) were significantly increased due to the addition of amendments. However, the decline in available N with incubation period was only marginal when nitrogen was applied along with amendments. An increase in NH4-N at 30 DAI might be due to the release of nutrients. A slight increase in the nitrate-N content of the soil was observed at the end of the incubation period due to microbial oxidation of NH4-N to NO3-N. The application of amendments could save a quantity of N dose besides reclaiming the sodicity

Modeling electrochemical systems with weakly imposed Dirichlet boundary conditions

Finite element modeling of charged species transport has enabled analysis, design, and optimization of a diverse array of electrochemical and electrokinetic devices. These systems are represented by the Poisson-Nernst-Planck equations coupled with the Navier-Stokes equation, with a key quantity of interest being the current at the system boundaries. Accurately computing the current flux is challenging due to the small critical dimension of the boundary layers (small Debye layer) that require fine mesh resolution at the boundaries. We resolve this challenge by using the Dirichlet-to-Neumanntransformation to weakly impose the Dirichlet conditions for the Poisson-Nernst-Planck equations. The results obtained with weakly imposed Dirichlet boundary conditions showed excellent agreement with those obtained when conventional boundary conditions with highly resolved mesh we reemployed. Furthermore, the calculated current flux showed faster mesh convergence using weakly imposed conditions compared to the conventionally imposed Dirichlet boundary conditions. We illustrate the approach on canonical 3D problems that otherwise would have been computationally intractable to solve accurately. This approach substantially reduces the computational cost of model-ing electrochemical systems.Comment: 24 pages, 14 figure

Size and weight reduction in Holothuria scabra processed as beche-de-mer

Growing demand for beche-de-mer in the marine export market has naturally led to considerable debate among fishery biologists in our country on the problem of irrational exploitation of the natural stock. Along the Tamil Nadu coast Holothuria scabra is fished for beche-de-mer preparation. Studies on the size at first maturity indicated that the spawning size is 201-230 mm and this size group after processing attains a reduced size of 73-80 mm. Revival of the natural stock can take place and this would help in encountering specimens beyond the size of 75 mm in length. More studies are required on the biology of Holothurians to determine precisely the period of maturity and spawning in different species in a year and it is advisable to observe a 'closed season' each year to conserve the holothurian resources

Design and Development of a Decision Support System for Safety Management of Rotary Pump Systems

Increasing technological advancement and complexity have made it necessary to develop more effective approaches to safety, reliability and quality. This paper presents the design and development of decision support system for safety management of rotary system using computational intelligent techniques. The rotary system considered for this research paper is centrifugal pumping system. This paper presents the application of Neural Network approach for fault detection and fuzzy logic approach for fault diagnosis in centrifugal pumping system. This paper highlights the development of decision support system integrating all the subsystem for a real-world application of computational intelligent techniques to solve a complex problem, which contributes to the prevention of accidents and preparation for emergency response. The results are compared and the conclusions are presented which demonstrate the possible application of industrial use

Synthesis and characterization of pure and Co-doped gallium nitride nanocrystals

n/

Studies on the biology, ecology and fishery of the sea cucumber Holothuria (Metriatyla) scabra (Jaeger) from south east coast of India

Among the echinoderms, holothurians (also known as 'Sea cucumbers) are commercially important. Introduced by the Chinese, they are in existence in the Gulf of Mannar and Palk Bay for more than one thousand years