Some studies relating to the design of shallow, fluidized bed boilers

The concept of shallow fluidized bed boilers is defined and a preliminary working design for a gas-fired package boiler has been produced. Those areas of the design requiring further study have been specified. Experimental investigations concerning these areas have been carried out. A two-dimensional, conducting paper analog has been developed for the specific purpose of evaluating sheet fins. The analog has been generalised and is presented as a simple means of simulating the general, two-dimensional Helmholtz equation. By recording the transient response of spherical, calorimetric probes when plunged into heated air-fluidized beds, heat transfer coefficients have been measured at bed temperatures up to 1 100°C. A correlation fitting all the data to within ±10% has been obtained. A model of heat transfer to surfaces immersed in high temperature beds has been proposed. The model solutions are, however, only in qualitative agreement with the experimental data. A simple experimental investigation has revealed that the effective, radial, thermal conductivities of shallow fluidized beds are an order of magnitude lower than the axial conductivities. These must, consequently, be taken into account when considering heat transfer to surfaces immersed within fluidized beds. Preliminary work on pre-mixed gas combustion and some further qualitative experiments have been used as the basis for discussing the feasibility of combusting heavy fuel oils within shallow beds. The use of binary beds, within which the fuel could be both gasified and subsequently burnt, is proposed. Finally, the consequences of the experimental studies on the initial design are considered, and suggestions for further work are made

A study on the quality of prawns during processing in prawn-freezing factories

A study on the occurrence of defective pieces of prawns at three different stages of processing of headless shell on and peeled and deveined varieties was undertaken, each in one freezing factory. The average percentages of the defective prawns together with the standard deviation observed over a period of one year at the three stages are mentioned. Correlation is indicated between the occurrence of the defective pieces at the pre-freezing stage and those of earlier stages

Hydrological conditions of marine fish culture ponds and adjacent inshore waters of Palk Bay near Mandapam during the North-East Monsoon period

In recent years, attempts were being made in India to utilise the coastal lagoons, estuaries and other water bodies for fish culture practices by which the protein uptake of our masses could be increased. Tampi (1960) has proved that the coastal lagoons with low biological productivity can be developed into fish farm

Artemether resistance in vitro is linked to mutations in PfATP6 that also interact with mutations in PfMDR1 in travellers returning with Plasmodium falciparum infections.

BACKGROUND: Monitoring resistance phenotypes for Plasmodium falciparum, using in vitro growth assays, and relating findings to parasite genotype has proved particularly challenging for the study of resistance to artemisinins. METHODS: Plasmodium falciparum isolates cultured from 28 returning travellers diagnosed with malaria were assessed for sensitivity to artemisinin, artemether, dihydroartemisinin and artesunate and findings related to mutations in pfatp6 and pfmdr1. RESULTS: Resistance to artemether in vitro was significantly associated with a pfatp6 haplotype encoding two amino acid substitutions (pfatp6 A623E and S769N; (mean IC50 (95% CI) values of 8.2 (5.7 - 10.7) for A623/S769 versus 623E/769 N 13.5 (9.8 - 17.3) nM with a mean increase of 65%; p = 0.012). Increased copy number of pfmdr1 was not itself associated with increased IC50 values for artemether, but when interactions between the pfatp6 haplotype and increased copy number of pfmdr1 were examined together, a highly significant association was noted with IC50 values for artemether (mean IC50 (95% CI) values of 8.7 (5.9 - 11.6) versus 16.3 (10.7 - 21.8) nM with a mean increase of 87%; p = 0.0068). Previously described SNPs in pfmdr1 are also associated with differences in sensitivity to some artemisinins. CONCLUSIONS: These findings were further explored in molecular modelling experiments that suggest mutations in pfatp6 are unlikely to affect differential binding of artemisinins at their proposed site, whereas there may be differences in such binding associated with mutations in pfmdr1. Implications for a hypothesis that artemisinin resistance may be exacerbated by interactions between PfATP6 and PfMDR1 and for epidemiological studies to monitor emerging resistance are discussed

Aerosol optical depth studies during INDOEX: comparison of the spectral features over coastal India with the pristine southern hemispheric environment over Mauritius

Aerosol spectral optical depths, estimated using a ground-based network of multi wavelength radiometers (MWR) along the west coast of India [Trivandrum (TVM; 8.5°N, 77°E), and Minicoy (MCY; 8.3°N, 73.04°E)] and the pristine southern hemispheric environment at Mauritius (MRU; 20.26°S, 57.54°E) during the period January to June 1998 along with those obtained over the Arabian Sea and Indian Ocean during the INDOEX FFP-98 cruise (SK133) of ORV Sagar Kanya, are used to study the inter-hemispheric features of aerosols. Results indicate that there is a significant hemispherical difference for aerosol spectral optical depth (AOD) at shorter wavelengths (λ≤ 650 nm), while at the longer wavelengths (λ > 650 nm), AOD does not show any appreciable variation with location. The spectral variation of AOD at TVM and MCY (for March 1998) depicted a similar pattern with the AOD values between 0.5 and 0.6 at shorter wavelengths and between 0.2 and 0.4 at longer wavelengths. In contrast to this, the AOD at MRU are very low, lying in the range 0.1 to 0.2 in the shorter wavelengths, whereas at the longer wavelengths the AOD values are more or less comparable (in the range 0.2 to 0.4) with the northern hemispheric stations. The cruise data clearly showed that the transition occurs generally across the ITCZ. The increased AOD at shorter wavelengths in the northern hemisphere indicates higher concentration of sub-micron aerosols in these environments arising mainly due to anthropogenic activities, while the AOD at the longer wavelengths is attributed mainly to be of marine origin. In the post-cruise period, the spectral optical depths showed a gradual increase from March to June at MRU, while at TVM, the pattern followed more or less the climatological mean. By May the AOD at shorter wavelengths decreased at TVM (due to increased rainfall) and by June, the AOD at TVM are very much comparable with those seen at MRU, indicating a dominating marine aerosol influence at both these locations. The implications are discussed

Observations on the paddy-field prawn filtration of Kerala, India

Experiments were conducted to determine whether culture methods could be advantageously introduced into the existing prawn filtration practices in the paddy fields of Kerala, on the southwest coast of India. The pattern of the fishery is changing, with the demand for small prawns decreasing and that for large prams increasing

Some aspects of hydrobiological study on the shelf waters off Bombay

Variations in salinity, temperature, dissolved oxygen and zooplankton biomass in the shelf waters off Bombay where the exploratory fishing vessels were operating, studied for one year from April 1972 to April 1973. Hydrographic features in the locality diowed double oscillations. Zooplankton biomass exhibited two peaks - one immediately before and the other soon after the southwest monsoon, the latter being secondary in nature. List of dominant zooplankters found in the area in various months are given in the order of their abundance

Effect of sailkite in improving trawl gear performance

Effectiveness of sailkite has been evaluated in two trawl designs, namely, a 25m high opening trawl and a 32m large mesh demersal trawl, rigged with sailkite through full scale comparative field trials. A 25m high opening trawl showed significant increase in total catch by 54.4% ribbon fish (Trichiurus spp.) alone by 138.3% with a reduction in miscellaneous catch, comprising mostly small sciaenids and juvenile fish, by 13.2% while 32m large mesh demersal trawl showed an improvement in total catch by 9%, ribbon fish by 17.2% and miscellaneous catch by 7.7%. The difference in fishing performance between the two gear arrangements has been attributed to changed net mouth configuration because of higher head line lift and also the possible herding effect on the fish in the vicinity of trawl mouth, due to addition of sailkite

On the occurrence of mature penaeid prawn Penaeus merguensis in a shallow solar salt works reservoir along the Okhamandal Coast of Gulf of Kutch and its spawning in laboratory

Penaeus merguensis is so far reported to attain complete maturity and spawn in the sea or deep culture ponds only. Mature specimens of stage III to V collected from a shallow reservoir of solar saltworks were studied and spawned in laboratory. A comparison of spawning of spawner from sea and reservoir is also reported

Faecal streptococci in fresh frozen shrimp

Present limit of faecal streptococci as 100/g in fresh frozen shrimp was found to be too strict a standard commercially prepared products. Statistical analysis of the data collected indicates that fixing the maximum permissible limit as 1000/g will be a more workable proposition