Evaluation of chemical tests for the quality of prawns

The object of this study was to determine the value of physical, bacteriological and chemical tests used to find out and compare the indices of quality of prawns stored at 0°C and at 18°C. pH value, nature of drip, the total bacterial count, presence or absence of tryptophan, trimethylamine content, glycogen, lactic acid, vitamins such as thiamin, riboflavin and niacin were estimated periodically to evaluate the quality of prawns stored at 0°C, whereas in addition to organoleptic changes, pH, bacterial count, nature of growth in peptone water, soluble protein in salt solution and loss of moisture, glycogen, lactic acid, and changes in vitamin B contents were noted periodically for prawns stored at -l8°C. Riboflavin and niacin were not affected appreciably but the retention of thiamin in prawns was very low.

Chemical composition of Bombay ducks (Harpodon nehereus) and changes occurring in the nutritive value of dried Bombay ducks on storage

Fresh Bombay ducks and Bombay ducks dried (a) without any pre-treatment or (b) after brining with NaCl solutions of 15% and 7.5% concentrations for 18 hours were analyzed for moisture, ash, minerals, vitamins, fat, free fatty acids, peroxide value, thiobarbituric acid value, total protein, total amino nitrogen, soluble proteins and trimethylamine contents. All the dried samples were stored in (a) tightly closed tin containers or (b) polythene bags and analyzed for the above mentioned constituents every 1½ months. It was observed that brining did not exercise any marked influence on keeping properties. Organoleptic observations showed that fish stored in tin containers kept better and longer than those stored in polythene bags.

Seasonal variation in the chemical composition of pomfrets. Pt. 1. Black pomfret (Parastromateus niger)

Seasonal variations in proximate composition of the different parts such as head, middle, tail and skin of black pomfret (Parastromateus niger) are reported over three years on monthly basis. The lean and fatty conditions of fish are discussed on the basis of spawning period, food and feeding activity, size group appearance and the gonadal maturity of the pomfret.

Studies on some physico-chemical factors of Kaptai lake

The present investigation dealt with the climatic and some physico-chemical conditions of the Kaptai lake with respect to their monthly variation. Air temperature was found always higher than water temperature. Vertical variation in temperature (0.8-4.7°C) was observed in all months. The water level fluctuates appreciably throughout the year. Wide seasonal fluctuations were also noted in water transparency. The lake was found to be slightly hard and alkaline pH. Dissolved oxygen (DO) (6.4-9.1 mg/l) and free carbondioxide (4.7- 6.0 mg/l) contents showed favourable condition for aquatic lives. DO at different depth has shown no wide variation (1.0-2.4 mg/1). Conductivity ranged between 91.9±7.1 and 106.4 ±5.2 mS/cm.

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.

Deposition of diamond-like carbon films by photon-enhanced chemical vapour deposition of methane using a windowless hydrogen lamp

Thin films of diamond-like carbon (DLC) have been deposited using a novel photon-enhanced chemical vapour deposition (photo-CVD) method. This low energy method may be a way to produce better interfaces in electronic devices by reducing damage due to ion bombardment. Methane requires high energy photons for photolysis to take place and these are not transmitted in most photo-CVD methods owing to the presence of a window between the lamp and the deposition environment. In our photo-CVD system there is no window and all the high energy photons are transmitted into the reaction gas. Initial work has proved promising and this paper presents recent results. Films have been characterized by measuring electron energy loss spectra, by ellipsometry and by fabricating and testing diode structures. Results indicate that the films are of a largely amorphous nature and are semiconducting. Diode structures have on/off current ratios of up to 106.

Chemical analyses of some Ceylon fishes - 2

Sri Lanka is an island surrounded by the Indian Ocean. Many varieties of marine species of fishes are caught in waters surrounding the island. The catches vary from coast to coast with the monsoonal fluctuations. The island is geographically situated in the tropical latitudes of high rainfall. The topographical landscape presents a central cluster of peaks surrounded by vistas of plains. Hence inland water bodies rise and meander in different directions of the country resulting in heterogeneous habitats yielding a host of freshwater fishes. As the different types of marine and freshwater fishes are manifold, an investigation into the nature and constituents of various species from a chemical standpoint was initiated by Lantz and Gunasekera (1957). Their paper was with a view to rendering possible a better commercial utilization of fishes. The present work is an extension of the above with necessary deviations. Lantz and Gunasekera (1957) had published results of 30 species of Sri Lanka fishes. The present paper introduces results of 5 species and investigations are being continued to cover other species. Investigations appearing in this paper were on fish samples obtained from different sales points in Colombo.

Chemical analyses of some Ceylon fishes - 3

Chemical analyses of fishes found in Sri Lanka were initiated by Lantz and Gunasekera (1957), who presented data from examination of 30 different species of fishes. Later Peiris and Grero (1972) published the analysed data of 5 more species. The present paper continues the analyses and the results obtained from 10 more varieties of marine fishes are given.

Environmental and social impact monitoring of the Bujagali Hydropower Project (BHPP), Uganda Fisheries Component: monthly patterns in physico-chemical conditions and fish catch in the immediate vicinity of the Bujagali Hydropower construction site, 29th September - 28th October 2007

Following the commencement of construction works of a 250 MW hydropower plant at Dumbbell Island in the Upper Victoria Nile in September 2007, BEL requested NaFIRRI to conduct continuous monitoring of fish catches at two transects i.e. the immediate upstream transect of the project site (Kalange-Makwanzi) and the immediate downstream .transect (Buyala-Kikubamutwe). The routine monitoring surveys were designed to be conducted twice a week at each of the tWo transects. It was anticipated that major immediate impacts were to occur during construction, and these needed to be known by BEL as part of a mitigation strategy. For example, the construction of it cofferdam could be accompanied by rapid changes in water quality and quantity downstream of the construction. These changes in turn could affect the fish catch and would probably be missed by the quarterly monitoring already in place. Therefore, a major cbjective of the more regular and rapid monitoring was to discern immediate impacts of construction activities by focusing on selected water quality parameters (total suspended solids, water conductivity, temperature, dissolved oxygen and pH) and fish catch characteristics (total catch, catch rates and value of the catch)

SU8 bio-chemical sensor microarrays

Microfabricated cantilevers have recently attracted considerable attention as novel label-free chemical and biological biosensors which translate surface reactions into nanomechanical bending motion. However these studies have primarily focused on commercially available silicon cantilevers and relatively little work has been performed on cantilevers fabricated from other materials. Polymeric materials, offer significant advantages over silicon by virtue of the low Young's modulus, ease of microfabrication and reduced cost. In this paper, we report a non-vacuum fabrication process to produce arrays of SU8 cantilevers and demonstrate their application as chemical sensors using in situ reference cantilevers. © 2006 Elsevier B.V. All rights reserved.

Diffusion and chemical reaction in the porous structures of solid oxide fuel cells

The Rolls-Royce Integrated-Planar Solid Oxide Fuel Cell (IP-SOFC) consists of ceramic modules which have electrochemical cells printed on the outer surfaces. The cathodes are the outermost layer of each cell and are supplied with oxygen from air flowing over the outside of the module. The anodes are in direct contact with the ceramic structure and are supplied with fuel from internal gas channels. Natural gas is reformed into hydrogen for use by the fuel cells in a separate reformer module of similar design except that the fuel cells are replaced by a reforming catalyst layer. The performance of the modules is intrinsically linked to the behaviour of the gas flows within their porous structures. Because the porous layers are very thin, a one-dimensional flow model provides a good representation of the flow property variations between fuel channel and fuel cell or reforming catalyst. The multi-component convective-diffusive flows are simulated using a new theory of flow in porous material, the Cylindrical Pore Interpolation Model. The effects of the catalysed methane reforming and water-gas shift chemical reactions are also considered using appropriate kinetic models. It is found that the shift reaction, which is catalysed by the anode material, has certain beneficial effects on the fuel cell module performance. In the reformer module it was found that the flow resistance of the porous support structure makes it difficult to sustain a high methane conversion rate. Although the analysis is based on IP-SOFC geometry, the modelling approach and general conclusions are applicable to other types of SOFC.

Improved chemical methods for extraction of fin rays from shark fins

A survey was undertaken of methods available for the extraction of fin rays from shark fins. The development of new, quicker and easier methods of processing is presented.

Evaluation of quality of shark livers using bio-chemical properties and organoleptic score sheet

Shark livers are considered as an important raw material providing a quality fish oil. It has been reported to aid white — blood-cell production and act as an active ingredient in hemorrhoid treatments. It is also reported that liver oil as a good supplement of vitamin A and poly-unsaturated fatty acids which are important to the development of brain cells in human. Freshness of livers is very important to extract better quality oil. In Sri Lanka, the annual shark production amounts to 8000t, however the quality of livers collected from landing sites has not being measured yet. Present study was conducted to evaluate the quality of silky (Charcarninus fakiformis) shark livers available in Negombo and Beruwala landing sites in the West Coast of Sri Lanka and also to study the relationship between organoleptic and bio-chemical correlation on freshness of shark livers. Liver samples which were collected from landing sites in the West coast of Sri Lanka, were evaluated for external and internal colour, texture and odour. Total volatile nitrogen (TVN), pH value, free fatty acid (FFA%) and peroxide (PV) values of livers were also determined to assess quality. According to the organoleptic scoring system 4.3% of liver samples were categorized as best in quality while 30.4%, 56.5% and 8.7% rated as good, medium and poor in quality respectively at the Negombo and Beruwala landing sites. Bio-chemical analysis showed that the better quality livers had the highest score for sensory evaluation and low values for TVN, FFA and peroxide value while low quality livers gave low score for sensory evaluation and high TVN, FFA, peroxide values. Correlation coefficient of organoleptic scores against total volatile nitrogen value, pH value, free fatty acid % and peroxide value of shark livers were determined by statistical analysis. Organoleptic score of shark livers was found to be highly.

Smart chemical sensor application of ZnO nanowires grown on CMOS compatible SOI microheater platform

Smart chemical sensor based on CMOS(complementary metal-oxide- semiconductor) compatible SOI(silicon on insulator) microheater platform was realized by facilitating ZnO nanowires growth on the small membrane at the relatively low temperature. Our SOI microheater platform can be operated at the very low power consumption with novel metal oxide sensing materials, like ZnO or SnO2 nanostructured materials which demand relatively high sensing temperature. In addition, our sol-gel growth method of ZnO nanowires on the SOI membrane was found to be very effective compared with ink-jetting or CVD growth techniques. These combined techniques give us the possibility of smart chemical sensor technology easily merged into the conventional semiconductor IC application. The physical properties of ZnO nanowire network grown by the solution-based method and its chemical sensing property also were reported in this paper.