Changes in proteasome activity during postmortem aging of bovine muscle

The effects of adding commercial-grade and eggshell calcium lactate on the microbiological and physicochemical properties of Nhams (Thai-style fermented pork sausage) were studied. The Nham calcium levels were 150, 300 and 450 mg/100 g. Compared to controls (no added calcium), calcium fortification did not affect the number of lactic acid bacteria or the colour value. The shear force of Nhams fortified with eggshell calcium lactate decreased (P<0.05) from 32.2 N in the controls to 19.5-22.8 N in Nhams fortified with eggshell calcium lactate. However, Nhams fortified with commercial calcium lactate had the same shear force as the controls. Sensory scores of sour taste, flavour and overall acceptance were not different between the control and calcium-fortified Nhams at a calcium level of 150 mg/100 g.     

An experimental investigation of formality in UML-based development

The object constraint language (OCL) was introduced as part of the Unified Modeling Language (UML). Its main purpose is to make UML models more precise and unambiguous by providing a constraint language describing constraints that the UML diagrams alone do not convey, including class invariants, operation contracts, and statechart guard conditions. There is an ongoing debate regarding the usefulness of using OCL in UML-based development, questioning whether the additional effort and formality is worth the benefit. It is argued that natural language may be sufficient, and using OCL may not bring any tangible benefits. This debate is in fact similar to the discussion about the effectiveness of formal methods in software engineering, but in a much more specific context. This paper presents the results of two controlled experiments that investigate the impact of using OCL on three software engineering activities using UML analysis models: detection of model defects through inspections, comprehension of the system logic and functionality, and impact analysis of changes. The results show that, once past an initial learning curve, significant benefits can be obtained by using OCL in combination with UML analysis diagrams to form a precise UML analysis model. But, this result is however conditioned on providing substantial, thorough training to the experiment participants.     

Dynamic Control with Indistinguishable Events

We consider the problem of synthesizing controllers for dicrete event systems with indistinguishable events. The specification for the supervised system as well as the constraints for the controllers are defined by an extension of the logic of the μ-calculus that generalize the framework introduced by Ramadge and Wonham. More precisely, in order to express that some events are indistinguishable, one can specify with this extension that, from a node of a graph, two edges reach the same node. As for the μ-calculus, the model cheking problem and also the emptiness problem for this extension amount to computing winning strategies in parity games. We show that the centralized control problem with indistinguishable events is decidable by reducing it to the satisfiability problem of a formula of this extension of the μ-calculus. We prove also that, unfortunately, the decentralized control problem is undecidable by a reduction of the halting problem of a Turing machine. Moreover, we exhibit a decidable case of decentralized control by restricting the specifications to those which we called here “conic”.     

A validation of object-oriented design metrics as qualityindicators

This paper presents the results of a study in which we empirically investigated the suite of object-oriented (OO) design metrics introduced in (Chidamber and Kemerer, 1994). More specifically, our goal is to assess these metrics as predictors of fault-prone classes and, therefore, determine whether they can be used as early quality indicators. This study is complementary to the work described in (Li and Henry, 1993) where the same suite of metrics had been used to assess frequencies of maintenance changes to classes. To perform our validation accurately, we collected data on the development of eight medium-sized information management systems based on identical requirements. All eight projects were developed using a sequential life cycle model, a well-known OO analysis/design method and the C++ programming language. Based on empirical and quantitative analysis, the advantages and drawbacks of these OO metrics are discussed. Several of Chidamber and Kemerer's OO metrics appear to be useful to predict class fault-proneness during the early phases of the life-cycle. Also, on our data set, they are better predictors than “traditional” code metrics, which can only be collected at a later phase of the software development processes     

Impact of the lysine-188 and aspartic acid-189 inversion on activity of trypsin

The presence of heat stress protein genes (hsp) was tested by Southern hybridization analysis in total DNA extracts from species of the genus Streptococcus (47 strains), Lactobacillus (34 strains), Lactococcus (24 strains), and Leuconostoc (5 strains). The biotinylated hsp16.4 probe prepared from an ORF2 fragment of pER341 (2.8 kb) tested positively with restricted DNA extracts of seven Streptococcus thermophilus strains and a single strain of Lactococcus lactis subsp. cremoris. In all positive S. thermophilus strains, the hsp was located on plasmids ranging from ca. 2.8 kb to 11 kb in size, while hsp was present in a 7.5-kb plasmid in Lactococcus lactis subsp. cremoris. Southern blots with a rep probe showed that all hsp16.4+ plasmids in S. thermophilus strains also shared homology with the replication function (rep) of pER341, suggesting the common origin of these plasmids.     

Enantioselective esterification of ibuprofen with ethanol as reactant and solvent catalyzed by immobilized lipase: experimental and molecular modeling aspects

BACKGROUND: In recent years enantioselective esterification of racemic ibuprofen performed in organic co‐solvent media such as isooctane and cyclohexane and catalyzed by lipases, has been proposed as an effective way to increase the concentration of S‐ibuprofen in the racemic mixture. In this contribution, the enantioselective enzymatic esterification of (R,S)‐ibuprofen with ethanol catalyzed by commercial Novozym 435 without the addition of a co‐solvent is thoroughly investigated. Experimental data are further analyzed considering the results of extensive molecular modeling calculations. RESULTS: The conversion of ibuprofen towards the ethyl esters and the enantiomeric excess towards S‐ibuprofen are greatly affected by the ethanol and water contents of the reaction media. The optimum conditions for the esterification of racemic ibuprofen in a batch‐type reactor were as follows: molar ratio of ethanol to ibuprofen = 7, 4.8% v/v of water, 160 mg of Novozym 435, 45 °C and 200 rpm. Under these conditions an enantiomeric excess of 54% and 63% of ibuprofen conversion were reached. CONCLUSIONS: Results showed that the reaction in excess of the esterifying alcohol in a system free of additional organic solvents is possible if the proper conditions are set. Molecular modeling calculations demonstrated that the formation of dead‐end compounds between the enzyme and ethanol/water may account for lipase inhibition at high concentrations of those compounds. Copyright © 2009 Society of Chemical Industry