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Notes: Concepts from the theory of interacting continua are employed to develop constitutive relations for liquid and/or gas saturated elastic porous media. The model is formulated by defining intrinsic stress tensors and densities in terms of the partial stress tensors, partial densities, and actual volume fractions occupied by each component. It is assumed that the constitutive law for each component as a single continuum relates intrinsic pressure to intrinsic deformation. Relative motion between the constituents is allowed through simple Darcy-type expressions. The governing equations together with the constitutive relations are used to investigate the propagation of both harmonic and transient pulses. In general three modes of wave propagation exist. In the case of a transient pulse, these modes lead to a three-wave structure. Laplace transform techniques are used to derive closed-form solutions for transient loading for two limiting values of viscous coupling (i.e., weak viscous coupling, strong viscous coupling). Strong viscous coupling results in the coalescence of the three wave fronts into a single front. Solutions for the general case of transient loading are obtained by numerical inversion of the Laplace transforms.

Notes: A pilot scale (10 1) fermenter trial was conducted for the production of cellulase enzyme and single cell protein by growing a cellulolytic mould Aspergillus terreus GN1 on 1.0% alkali-treated sugar cane bagasse substrate. A maximum crude protein content of 29.8% in the biomass was obtained during 4 days fermentation from the initial alkali-treated bagasse having 3.0% crude protein content. The carboxymethyl cellulase (CMCase) activity was almost 0 u/ml during the first 24 hr, which increased during 96 hr incubation to 0.52 u/ml, and corresponded with the highest filter paper enzyme (FPase) activity of 0.032 u/ml. There was an alternate decrease and further increase in water soluble carbohydrate during 96 hr incubation, which increased finally to 7.9%. There was no cellulose utilization during the first 24 hr of incubation. However, the cellulose of sugar cane bagasse substrate was utilized subsequently and a maximum of 72.5% of the initial cellulose was utilized up to 96 hr fermentation time.

Notes: Four different fertilization frequencies, namely twice per week, once per week, twice a month and once a month, were used in ponds to assess their effects on nutrient release, pond productivity and fish biomass. All ponds received the same total fertilizer inputs during the experimental period of 60 days (cow dung 208.3 kg ha−1 week−1, TSP 9.8 kg ha−1 week−1, urea 6.0 kg ha−1 week−1). Studies have revealed that the highest values of fish biomass, specific growth rate (SGR), net primary productivity (NPP), plankton population and nutrients were observed in the ponds that were fertilized twice a month. A strong and significant correlation of fertilization frequency was observed with dissolved oxygen, biochemical oxygen demand (BOD), alkalinity, nutrient release, NPP, plankton density (no. L−1), fish biomass and SGR. The linear relationship between NPP and fish biomass/SGR for all the ponds was strong (r2= 0.88). Sediment chemistry revealed that O-PO4, NO3-N, organic carbon and electrical conductivity (EC) increased significantly (P〈0.05) with a decrease in the frequency of fertilization, while alkalinity and calcium were high in ponds that were fertilized twice a month.

Notes: To study the effect of four different raw and hydrothermically processed leguminous seeds, namely Glycine max (soybean), Vigna radiata (moong), Vigna ungiculata (cowpea) and Cyamopsis tetragonaloba (guar) on growth in the fingerlings of Cirrhinus mrigala (mrigal) and Labeo rohita (rohu), two experiments were conducted. The first experiment was conducted under laboratory conditions (LD 12:12 at 25 °C) and the mrigal fingerlings were fed @2% BW d−1 for 30 days. Before using the seeds as feeds, they were hydrothermically processed (15 lbs at 121 °C for 15 min) for the elimination of antinutrient factors (ANF). The results indicate that 15 minute autoclaving significantly reduces the trypsin inhibitor activity. Phytase-phosphorous and tannins were also analysed from raw and treated beans. Studies on mrigal have revealed that weight gain was significantly low (P 〈 0.05) in the fish fed on raw beans compared with the fingerlings fed on processed bean proteins. Among the various raw diets used, significantly highest growth (P 〈 0.05) was observed in fish fingerlings fed on raw moong, followed by raw soybean, cowpea and guar. On the other hand, when beans were processed, the highest growth was observed in fingerlings fed on processed soybean. Studies have further revealed that hydrothermal processing also affected the values of the feed conversion ratio, gross conversion efficiency, protein efficiency ratio, gross protein retention, gross energy retention and ammonia excretion. Proximate composition of the carcass revealed high accumulation of protein, fat and energy in fingerlings fed on processed soybean in comparison with other diets. Keeping in view the higher weight gain in fish fed on hydrothermically processed bean proteins, only processed bean diets were fed to the fingerlings of mrigal and rohu stocked in fish ponds (experiment 2). A significant (P 〈 0.05) increase in mean fish weight, and specific growth rate was observed in fingerlings fed on hydrothermically processed soybean, followed by moong and cowpea. Weight gain for mrigal fingerlings remained significantly low in comparison to the rohu fingerlings fed on similar diets. An investigation on the effects of feeds on water quality parameters indicate that the trophic status of the ponds where soybean was used as fish feed remained high in comparison to the other treatments. A significant positive correlation of nutrients, NPP and plankton population with fish growth was also observed.