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Shellfish are found in the coastal region throughout the tropical, sub-tropic and temperate zone. A variety of shellfish species are known in nature. Being filter-feeding organisms, organic and inorganic substances easily gain entry into them. Very often, heavy metals such as Cd, Pb, Cu, and even Hg can accumulate in their bodies. The presence of these heavy metals in shellfish is an indicator of environmental pollution, and a threat to humanity as these fish are widely consumed in coastal regions. Here, biochemical analysis of exoskeleton shell mainly composed of polysaccharides, proteins and calcium carbonate (CaCO3) - have been studied. Calcium carbonate (CaCO3) which is one of the major constituent of the exoskeleton part of the shellfish exists in three polymorphs viz., calcite, aragonite and vaterite. The identification of CaCO3 polymorphs in shellfish is extremely important as it gives information on the structural arrangement of the calcium carbonate lattice in these organisms. Here, we present a convenient method for the identification of CaCO3 polymorphs in shellfish collected from Goa, west coast of India, with Fourier-Transform Infrared Spectroscopy (FTIR) and further confirmed by powder X-ray analysis. Additionally, the potential of the powdered shell biomass for metal removal from an aqueous medium has also been investigated. [ABSTRACT FROM AUTHOR]

The present study investigated the capability of the Weather Research and Forecasting (WRF) model in the forecast/simulation of five landfalling Bay of Bengal (BoB) cyclones during 2013. A 3D variational (3DVar) method of data assimilation of the WRF model was used to assimilate the Global Telecommunication System and satellite radiances to improve the initial conditions. The results demonstrated that the model has the ability to simulate the cyclone track, intensity and structure. The study also indicates that predicted storm track, landfall and intensity improved with the 3DVar technique compared to without it. This was due to better initial conditions in the 3DVar experiment. The predicted track errors of the five storms were compared to available global and regional forecasting systems and the results show that the model has the capability for prediction of cyclones over the BoB region. The forecasted mean track errors were about 70, 114, 182 and 184 km; minimum centre pressure was about 8, 10, 13, 13 hPa and maximum surface wind was about 6, 10, 9, 8 m·s−1 on day 1 to day 4 forecast respectively. The study also presents some of the important predicted diagnostic parameters such as temperature anomaly, divergence, heating rate, frozen hydrometeors, vorticity field, equivalent potential temperature, maximum reflectivity, accumulated rainfall and horizontal wind fields compared to available observations for the extremely severe cyclonic storm Phailin. The warm core structure of the Phailin cyclone was resolved in the model between 9 and 15 km compared to satellite observations. The statistical analysis, distribution and magnitude of forecasted accumulated rainfall are also compared to the rainfall of 174 automatic weather stations. [ABSTRACT FROM AUTHOR]

A Transimpedance amplifier (TIA)-based optical receiver in active voltage-current feedback topology is designed for optical interconnects at 0.18 μ m CMOS technology. The proposed inductorless TIA incorporates a gain boosting amplifier in its path to achieve high gain and bandwidth. This gain boosting amplifier is based on a regulated gain cascode (RGC) amplifier. The RGC stage raises the g m of the circuit, reducing the input resistance of the input stage; as a result, the bandwidth extends. To further amplify the gain, a common source (CS) stage is used at the output without much effect on the system's overall bandwidth. An analytical model of the proposed TIA is developed and later simulated at room temperature in the Cadence Virtuoso analog design environment. The pre-layout and post-layout simulation results of the proposed TIA have been shown to validate its performance. It achieves a transimpedance gain of 62 d B Ω while consuming power of 14.5 mW from a 1.8 V supply voltage. The bandwidth is extended to 8.2 GHz from 1.83 GHz with an input photodiode capacitance of 300 fF. The current spectral density of input-referred noise is 31 pA/ H z. [ABSTRACT FROM AUTHOR]

Bacterial wilt or brown rot caused by Ralstonia solanacearum is one of the most damaging diseases of potato worldwide. Strains of R. solanacearum have conventionally been classified into five races (r) and six biovars (bvs). Based on variation of DNA sequences, R. solanacearum strains are now classified into four phylotypes that broadly reflect the ancestral relationships and geographical origin of the strains. These phylotypes can be further subdivided into sequevars based on phylogenetic analysis of the endoglucanase (egl) gene sequences. In the present study, bacterial wilt-infected potato plants/tubers were collected from various potato-growing regions of the East Khasi Hills and West Khasi Hills districts of Meghalaya (India) during summer and autumn of 2012 and 2013. A total of 114 bacterial isolates were recovered, whose identity was confirmed as R. solanacearum by PCR with the species-specific primers 759/760. Using the biovar (bv) classification scheme, 67 isolates (58.8%) were categorized as bv 2T, 41 (35.9%) as bv 2 and six as bv3 (5.3%). A phylotype-specific multiplex PCR assigned 67 (58.8%) isolates to phylotype IV (bv2T), 41 (35.9%) to phylotype II (bv2) and six (5.3%) to phylotype I (bv3). A phylogenetic analysis of partial sequences of the egl gene of all isolates clustered 59 phylotype IV (bv 2T) isolates closely to sequevar 8 (GenBank accession No. DQ657634). The remaining 8 phylotype IV (bv 2T) isolates did not cluster with any of the four sequevar, i.e. 8, 9, 10 and 11 that are defined with phylotype IV and formed a distinct sequevar group. All 41 phylotype II (bv 2) isolates clustered with sequevar 1 (EF371844); three phylotype I (bv 3) isolates with sequevar 30 (AB508598), and three phylotype I (bv 3) isolates with sequevar 47 (GU295014). This is the first study that demonstrates a considerable biovar and phylogenetic diversity among R. solanacearum that cause potato bacterial wilt in the Meghalaya state of India. [ABSTRACT FROM AUTHOR]