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This article presents an extensive experimental study coupled with statistical analysis on infrared (IR)-assisted freeze drying of tiger prawn (Penaeus monodon) in cuboidal geometry. The work aims to estimate quality attributes of freeze-dried prawn in terms of final product temperature (below protein denaturation temperature), rehydration ratio, and final moisture content as a function of process parameters, viz. IR temperature (55-65°C), distance between sample and IR heater (30-60 mm), sample thickness (10-25 mm) and freeze-drying time (5.5-6.5 h). Response surface methodology (RSM) has been employed using a three-parameter, three-level face-centered central composite design (FCCD) to develop multivariate regression models in order to evaluate the influence of process parameters on the quality of the freeze-dried prawn. Optimal drying conditions of 10-mm sample thickness, 60-mm sample distance from the IR heater, 65°C IR temperature, and freeze-drying time of 6.37 h have been established. Separate validation experiments at the derived optimal conditions ascertained the predictive ability of the developed model equations. The outcome of this study would contribute to the development of technical capabilities for the design of freeze dryers applicable to such high-valued foodstuffs. [ABSTRACT FROM AUTHOR]

The freshwater prawn, Macrobrachium rosenbergii, commonly called 'scampi,' is the most important culturable freshwater species of prawn with a fairly high growth rate, wide range of temperature (15-35°C) and salinity tolerance. The nutrients required by this species for growth and associated physiological functions are similar to those required by other crustaceans. Current data suggest that a digestible protein level of above 30% is required for maximum growth and protein efficiency. Ingredients such as mussel meat meal, squid meal, and shrimp meal serve as potential sources of protein in formulated diets. The complete quantitative requirements for all the essential amino acids for this prawn species have not yet been worked out. With respect to non-protein energy supply in the form of carbohydrate, studies indicated that scampi is capable of utilizing various carbohydrate sources efficiently. Dietary carbohydrate in the form of complex polysaccharides appears to be more effective as an energy source. Like other crustaceans, scampi also has limited ability to synthesize sterol from acetate and mevalonic acid. Quantitative estimates of the essential fatty acid require-ments have been made in post-larval scampi. Data on vitamin and mineral requirements are scarce. Recent developments in diet formulation, practical feeding practices and the aquaculture potential in India have been indicated with emphasis on sustainable production. [ABSTRACT FROM PUBLISHER]

A feeding trial was conducted in the laboratory (20-26°C) to evaluate the growth response, nutrient utilization and certain tissue biochemical changes in rohu, Labeo rohita, fingerling (average weight 3.0±0.47 g) fed with a natural and a prepared diet in 3 feeding regimens (T1, T2, and T3) for a period of 90 days. The main objective was to investigate live and prepared diet effects on growth rate and associated biochemical parameters. Three tanks per treatment were used as replicates. The T1 group was fed exclusively with mixed plankton as natural diet; the T2 group was fed a combination of prepared diet and mixed plankton in a ratio of 1:3; the T3 group was fed the prepared diet only. The three groups were provided with the same feeding rate. The best performance in terms of fish growth, nutrient utilization, protein and lipid deposition in muscle was observed in the T2 group. RNA/DNA ratio in liver and muscle was the highest in T2, followed by T3 and T1. A positive correlation (r = 0.71) was obtained in muscle RNA concentration with respective specific growth rate of fish in different dietary treatments, and the same was indicated in the case of muscle and liver RNA:DNA ratio and total RNA and DNA content, indicating growth changes were due to the different rates of protein retention. Perusal of the amino acid composition of whole body tissue of T2 and T3 groups of fish indicated comparatively high content of individual amino acids. Total ammonia excretion after feeding was comparatively less in the T2 group, indicating less amino acid catabolism. The present study revealed that supplementation of natural diet with prepared diet led to effective nutrient utilization, thereby ensuring improved performance and minimizing discharge of aquaculture wastes through reduced nitrogen excretion. [ABSTRACT FROM PUBLISHER]

Disorder-to-order reaction in stoichiometric Ni[sub 3]V and Ni[sub 75]V[sub 21.5]Nb[sub 3.5] alloys involve a cubic (fcc)-to-tetragonal (D0[sub 22] structure) transformation. The structural changes occurring during the transformation result in a lamellar morphology of D0[sub 22] domains with {110}[sub fcc]-type interfaces. The propagation of stacking faults across domain boundaries in Ni[sub 3]V and Ni[sub 75]V[sub 21.5]Nb[sub 3.5] has been studied using transmission electron microscopy. Different modes of propagation of stacking faults across these boundaries have been observed. These modes have been attributed to the generation of appropriate glide partials at the domain boundaries. The nature and the Burgers vectors of the glide partials have been identified using visibility and invisibility criteria. Computer simulation results have been used to substantiate the results of contrast experiments. Dislocation reaction mechanisms responsible for the generation of these glide partials have been identified. In the present work, special emphasis has been laid on the propagation mode by which stacking faults cross the domain boundaries in the same glide plane. [ABSTRACT FROM AUTHOR]

Purpose: To determine the affinity, density, and specificity of the binding sites of tritium-labeled prostaglandin F2alpha in membrane preparations of bovine iris-sphincter muscle and corpus luteum.Methods: Membrane preparations were incubated with 0.312-40.0 nM 3H-prostaglandin F2alpha in saturation experiments, or 8 nM 3H-prostaglandin F2alpha in competition studies, in the presence or absence of varying concentrations of unlabeled prostaglandin F2alpha or other prostaglandin receptor agonists. The affinity (Kd) and the density of the binding sites (Bmax) of 3H-prostaglandin F2alpha in the bovine iris-sphincter muscle were determined by Scatchard analysis. Reverse transcription polymerase chain reaction was performed with bovine iris-sphincter muscle and corpus luteum total RNA and the PCR products were hybridized with specific 32P-labeled probe for further confirmation of FP receptor expression.Results: Specific binding sites of 3H-prostaglandin F2alpha in the membranes of bovine iris-sphincter muscle are saturable with an affinity of 9.5 nM and a density of 596 fmoles/mg of protein. Prostaglandin E2, 17-phenyl trinor prostaglandin E2, and GR63799 (EP, EP1, and EP3 receptor agonists, respectively) inhibited 3H-prostaglandin F2alpha binding with an IC50 of 0.0048 microM, 0.0038 microM, and 0.044 microM, respectively. Fluprostenol, a specific FP receptor agonist did not inhibit 3H-prostaglandin F2alpha binding. In contrast, prostaglandin F2alpha and fluprostenol effectively inhibited 3H-prostaglandin F2alpha binding in the bovine corpus luteum with an IC50 of 0.031 microM and 0.037 microM, respectively.Conclusions: Our results demonstrate that in the bovine iris-sphincter muscle, FP receptors are not expressed and 3H-prostaglandin F2alpha binds to EP1 and EP3 receptor sites. RT-PCR results demonstrated that FP receptor mRNA, which is present in bovine corpus luteum, is probably absent in iris-sphincter muscle. [ABSTRACT FROM AUTHOR]