PURIFICATION AND CHARACTERIZATION OF A PROTEASE FROM THE PYLORIC CAECA OF MENHADEN (Brevoortia spp) AND MULLET (Mugil spp) FROM THE SOUTHWEST ATLANTIC REGION

A protease classified as trypsin was isolated and purified from the pyloric caeca of two species of fishes: Brevoortia spp (menhaden) and Mugil spp. (mullet). The characterization of both enzymes as trypsin was based on their molecular weight (24 kDa) determined by SDS-PAGE, their inhibition by some known trypsin inhibitors (PMSF, SBTI, TLCK and benzamidine), and their ability to hydrolyze the synthetic trypsin substrate N-α-Benzoyl-DL-arginine-p-nitroanilide (BAPA). Menhaden trypsin had maximum activity at pH 9.5 and was stable for 30 min between pH 6.0 and 10.0 at 0, 10 and 25C. On the other hand, mullet trypsin showed maximum activity at pH's from 7.8 to 9.0, and was stable over a wider pH range (7.0–10.0). The optimum temperature for menhaden and mullet trypsin was 63C and 60C respectively. Thermostability for menhaden trypsin was up to 50C, whereas mullet trypsin was stable up to 60C. The Km(BAPA) values for menhaden trypsin were conserved in the temperature range from 10 to 30C, while for mullet trypsin the Km(BAPA) was conserved between 10 and 25C.     

Ownership Structures in Network Industries when the Rationality of Regulators is Bounded

This paper analyses the implication for allocative efficiencyof diffrent ownership structures of vertically related industriesin a simple game-theoretic setting. The upstream sector is monoplizedand regulated, while the downstream sector is imperfectly competitive.Regulation is imperfect in that the regulatory authority suffersfrom bounded rationality, and is not able to enforce optimalregulation. We consider both bomogenous and differentiated compositegoods. It generally turns out that when the regulator's enforcementcapabilities are limited, preventing the upstream monoplistfrom entering the downstream industry is socially undesirableunless the independent downstream rival enjoys a substantialproduction cost advantage. This holds true in spiteof the downstreamindustry is socially undesirable, unless the independent downstreamrival enjoys a substantial production cost advantage. This holdstrue in spite of the incentiveof the vertically integrated monopolistto manipulate accounts in order to raise the costs of the downstreamrival. Such reasoning especially applies when composite goodsare close substitures for one another.     

An Optimal Value-Based Admission Policy and its Reflective Use in Real-Time Systems

This paper deals with planning system activities to support applications that have different contrasting requirements including timing constraints on tasks execution and correctness requirements. Our approach is based on a simple yet effective formulation of a value structure associated to the application tasks. Values are associated to each relevant outcome thus accounting for successful executions as well as for those which violate the application requirements. Moreover we assume degradable real time systems equipped with several execution techniques characterised by different execution costs and different levels of fulfilment of requirements (and associated reward). We propose an admission algorithm to select the part of the offered load to be executed, should overload occur. For all the admitted tasks the algorithm selects also the most suitable execution technique (among those available) to optimise the expected cumulated reward. We show that the algorithm provides the best solution to the optimisation problem resorting to the linear programming theory. Then we discuss the applicability of this result to systems operating in dynamic environments. A planner component is defined, responsible to collect information on the current status of the system and of its environment. The planner decides when a new plan is required, and dynamically executes the admission algorithm to properly tune the usage of system resources.     

EFFECT OF ANTEMORTEM JOURNEY AND LAIRAGE AT ABATTOIR ON RABBIT MEAT QUALITY

A study was conducted to determine the effects of journey duration (1 versus 3 h) and lairage time at abattoir (0 versus 5 h) on rabbit meat quality traits. Rabbits transported for 3 h produced meat with significantly higher pH values ( P <  0.01), darker (lower L* values, P <  0.01) and less yellow ( P <  0.05) color, as well as lower losses during cooking ( P <  0.01), than those transported for 1 h. Moreover, animals laired for 5 h yielded meat with more ( P <  0.05) yellow color, cooking losses ( P <  0.05) and higher shear values ( P <  0.01) than rabbits not laired before slaughtering. The nuclear magnetic resonance analysis revealed that these differences ( P <  0.05) are mainly related to changes occurring in the distribution of myofibrillar (T₂₁) and extra-myofibrillar (T₂₂) water. In conclusion, this study indicated that journey time and lairage at abattoir may play an important role in determining rabbit meat quality traits.

PRACTICAL APPLICATIONS

In many previous studies that considered the effect of journey and lairage on rabbit meat quality, animals were stress-induced by extreme conditions of journey and/or lairage that were unlikely to occur during commercial operations. The aim of this study is to establish whether meat quality characteristics are still influenced when journey and lairage times match current commercial production practices. Because processing-plant efficiency depends on product uniformity, it will be interesting to test the potential variability effect of rabbit preslaughter practices on meat quality properties.     

A multiaxial fatigue criterion for random loading

ABSTRACT A multiaxial fatigue criterion for random loading is proposed. Firstly, the orientation of the critical plane, where fatigue life estimation is carried out, is determined from the weighted mean position of the principal stress directions. Then, the scalar value of the normal stress vector N (t) perpendicular to the critical plane is taken as the cycle counting variable since the direction of such a vector is fixed with respect to time (conversely to the time‐varying direction of the shear stress vector C (t)), and a nonlinear combination of normal and shear stress components acting on the critical plane is used to define an equivalent stress amplitude. Finally, a damage accumulation model is employed to process such an equivalent stress amplitude and to determine fatigue endurance. This criterion is herein applied to some relevant random fatigue tests (proportional bending and torsion).     

A study of the interaction of sodium dodecyl sulphate with the proteins of human heel stratum corneum

The aim of this research is to study the in vitro interaction of the anionic surfactant sodium dodecyl sulphate with human heel callus with special regard to the callus proteins.
The sorption of SDS by callus is analysed at different pH values, demonstrating the expected maximum binding of the anionic surfactant at low pH. In both surfactant and blank solutions, swelling of the callus pieces occurs but to different extents. The sorption of SDS by callus is accompanied by a loss of free amino acids and proteins. The protein composition of the callus residues after chemical treatment and of the corresponding treatment baths is examined by amino acid analysis and shows differences in the respective molar amino acid ratios. Results obtained with more specific techniques, such as gel electrophoresis and immunoblotting, demonstrate identical as well as different protein components in the treatment baths depending on the experimental conditions (pH, blank or SDS). Although effects due to the surfactant treatment are in principle more distinct than with blank experiments, those of the latter cannot be neglected.