Measurement of moisture in dry cured fish by infrared irradiation

Heating conditions have been standardised for measurement of moisture in dry cured fish using infrared irradiation source of 150w. Results obtained are comparable to those obtained from standard air oven method (drying to a constant weight at l02°c), the mean deviation being less than two units. The method works equally well for fresh fish muscle.

Studies on technological problems associated with the processing of cooked frozen prawns. Pt. 1. Preprocess storage conditions of raw material in relation to quality

The chemical and organoleptic properties of prawn held in ice for different days prior to cooking and the changes after freezing and subsequent storage were studied with three different species of prawn viz. Metapenaeus monoceros, Metapenaeus dobsoni and Parapeneopsis stylifera. The optimum period for which the prawn can be kept under ideal conditions of icing prior to cooking has been worked out.

Studies on technological problems associated with the processing of cooked frozen prawns. Pt. 2. Hygienic conditions in relation to bacteriological characteristics

The importance of sanitary practices in the processing of precooked frozen shrimps has been discussed. Several typical examples have been shown to point out the different sources of contamination of the product and the extent to which each of the factors by itself or in combination affect the bacterial quality of the final product. A scheme of processing has also been suggested for controlling the microbial quality.

An accelerated method of hot air drying of fish

The effects of temperature and relative humidity on the rate of drying of split open fish and salted fish in a tunnel dryer have been studied at a constant air velocity. By a judicious combination of these two, the rate of drying could be considerably accelerated, 10 to 12 hours only being required for drying to moisture levels below 30% in the case of mackerel, lactarius, otolithes and kilimeen (Nemipterus japonicus)

Survival of antibiotic resistant Aeromonas strains in different water conditions

Studies were conducted to find out the survival of three antibiotic resistant Aeromonas strains in different types of water. The selected Aeromonas strains were A. hydrophila (local), A. sobria (local) and A. hydrophila (Thai), which were only recovered from farmed fishes. Seven types of water were used. Among these experimental water, lake water, distilled water and fish farm pond water had supported the long time survival of A. hydrophila. In contrast, private fish farm pond water was the most favorable for A. sobria. Deionized water was found not to support the survival of any species but Masjid pond water and FRI pond water were found to be moderately suitable for all the species. However, the survival pattern of Thai strain of A. hydrophila was found to have similarity with the survival of the local strain of A. hydrophila.

Limnological conditions of naturally turbid ponds and its effects on fish growth

An experiment was conducted on six naturally turbid ponds in the village of Salakandi situated to the south-west corner of Bangladesh Agricultural University, Mymensingh for a period of three months from July to September '96. The experiment was performed by studying the physicochemical factors of water and soil, the biological factors such as densities of phytoplankton and zooplankton, and the growth of fishes. During the experimental period water turbidity varied among ponds. The highest value of turbidity was found to be 679±183.6 FTU in pond 1 and the lowest was 158±23.31 FTU in pond 4. The maximum and the minimum water transparency were recorded in the month of July and September respectably. The lowest net weight of fishes was found 28.8 kg/ha/year in pond 1 due to high turbidity and the highest was 35.8 kg/ha/year in pond 4 due to low turbidity. Most of the correlations between turbidity and transparency, phytoplankton, and zooplankton were significant at 1% and 5% levels.

Socio-economic conditions of the pond owners of Demra, Dhaka

On the basis of fish culture status 96 ponds of the study area were classified into 4 categories like wild stock (27%), extensive culture (24%), improved extensive culture (33%) and semi-intensive culture (16%). Percentage of small, medium and large ponds were 38, 44, and 18 respectively whereas education levels below SSC, below Bachelor and above were 43, 38 and 19 respectively and single owners belonged to 54% of the ponds. Per hectare yields of extensive, improved extensive and semi-intensive categories of culture were 1.3, 2.12 and 4.0 metric tons respectively and their net return were 46, 63 and 92 thousand taka respectively. Considering the problems of fish culture, multiple ownership was found to be the most important one.

Effect of deposition conditions on the chemical bonding in sputtered carbon nitride films

A balanced planar r.f. powered magnetron sputter source has been used to deposit carbon nitride films from a graphite target under various conditions. Sample temperature, bias voltage and nitrogen content in the gas mixture were varied. The effects of oxygen, methane and ammonia on the film growth were also studied. Special attention was paid to the effects of the deposition parameters on the structure of the films, in particular the hybridisation of the carbon and nitrogen bonding. The chemical bonding of the carbon and nitrogen atoms was studied by electron energy loss spectroscopy (EELS). The chemical composition was evaluated by Rutherford back-scattering. The intensity of transitions to π antibonding orbitals, as revealed by EELS, was found to increase with the nitrogen content in the films. Ion bombardment of the films during growth and the addition of oxygen or hydrogen-rich gases further increased the proportion of π bonds of both the carbon and nitrogen atoms. It is suggested that the increase in the transitions to μ antibond orbitals is to be explained by increased sp2 or possibly sp hybridisation of the carbon and nitrogen. Also, the effect of annealing on the bonding of nitrogen rich films after deposition was tested. The changes caused by nitrogen and deposition conditions are consistent with previous reports on the formation of paracyanogen structures.

Identification of support conditions of buried pipes using a vibrating pig

This paper describes a method for monitoring the variation in support condition of pipelines using a vibration technique. The method is useful for detecting poor support of buried pipelines and for detecting spanning and depth of cover in sub-sea lines. Variation in the pipe support condition leads to increased likelihood of pipe damage. Under roadways, poorly supported pipe may be damaged by vehicle loading. At sea, spanned sections of pipe are vulnerable to ocean current loading and also to snagging by stray anchors in shallow waters. A vibrating `pig' has been developed and tested on buried pipelines. Certain features of pipe support, such as voids and hard spots, display characteristic responses to vibration, and these are measured by the vibrating pig. Post-processing of the measured vibration data is used to produce a graphical representation of the pipeline support and certain `feature characteristics' are identified. In field tests on a pipeline with deliberately constructed support faults, features detected by the vibrating pig are in good agreement with the known construction.

Studies on the phytoplankton of inshore and offshore waters off Colombo and some data on the hydrological conditions of these waters

The present paper gives a comparative account of the hydrological conditions and phytoplankton within the Continental Shelf and beyond the Continental Shelf. 54 water samples were taken for hydrological analysis and 18 surface tows for plankton.