Effect of biochemical storage on the denitrification potential of acetate in sequencing batch reactors.

This study evaluates the effect biochemical storage on the denitrification potential (N(DP)) of acetate. The fate of bacterial storage is evaluated in a sequencing batch reactor system operated in a sequence of anoxic/aerobic phases, fed with acetate as a pulse and continuously under anoxic conditions. N(DP) is defined based on system stoichiometry both for direct growth and storage on acetate. Experimental results do not support conceptual calculations based on system stoichiometry, yielding a higher denitrification potential, N(DP), for continuous feeding than the N(DP) obtained with pulse feeding, due to partial utilisation of the stored PHB within the anoxic phase. The nitrate, acetate and poly-beta-hydroxybutyrate (PHB) profiles obtained in the experimental studies were used in model calibrations for two different feeding patterns. Results of model simulations confirm the experimental results and evaluate the effects imposed on the denitrification potential by sludge age and the anoxic volume ratio.     

Diffusivities of volatiles in concentrated solutions

Concentration profiles obtained by slicing a cylindrical gel were used to measure diffusion of volatiles in viscous aqueous dextrose solutions. The column length, slice thickness and diffusion time were optimized to maximize the repeatability of measurements, the results being very sensitive to small changes in variables. Coefficients of variation between 5 and 10% were obtained. In the presence of different concentrations of dextrose, the diffusivity of acetone decreased markedly as dextrose concentration increased. However, when the acetone concentration was varied within the range 0·6 to 13·7%, at a constant 50% (w/w) dextrose concentration, its diffusivity did not change significantly. The sliced gel system gave values of diffusivity in close agreement with those obtained by other techniques.     

Proximate Composition, Mineral Content, and Fatty Acids of Catfish (Ictalurus punctatus, Rafinesque) for Different Seasons and Cooking Methods

The effect of conventional cooking methods and the influence of season upon proximate composition, mineral, and fatty acid profile was studied in catfish (Ictalurus punctatus, Rafinesque) fillets. Seasonal (August, December, and April purchased fillets) influences were minimal. As expected, fried catfish fillets had significantly altered (P ≤ 0.05) fatty acid profiles compared to the raw and baked fillets. All three cooking treatments resulted in significant differences (P ≤ 0.05) in proximate composition and in the levels of potassium, phosphorus, magnesium, and iron. The information presented would be useful for nutrient data banks when dietary intake of such items is of interest.     

Utilization of Defatted Sesame Flour in Fermented Salami

Fermented salami was prepared containing 0, 9, 18 and 27% defatted sesame flour (DSF). Chemical and sensory analyses were performed on the products. Results indicated that DSF could be used at either the 9 or 18% level without detrimental effect upon sensory attributes but salami containing 27% DSF will have less desirable flavor.     

Axisymmetric fracture mechanics analysis by the boundary integral equation method

The boundary integral equation (BIE) method of numerical stress analysis is shown to be a powerful technique for solving axisymmetric fracture mechanics problems of the types encountered in practice in pipes, tubes and pressure vessels. Comparisons with established analytical and finite element solutions for problems involving circumferential and penny-shaped cracks in round bars, spheres and hollow cylinders show that accurate values of stress intensity factors at the tips of cracks can be obtained by this method. The main advantage of the technique over the finite element method is the much reduced amount of labour required to prepare the mesh data, since in the BIE approach only the boundary of an axisymmetric component needs to be discretised into simple and relatively coarse line elements.