Chemical and microbiological quality of grass carp (Ctenopharyngodon idella) slaughtered by different methods

The effect of two slaughter methods (immersion in ice-water slurry and electrical stunning followed by ice slurry asphyxiation) on chemical and microbiological parameters of grass carp (Ctenopharyngodon idella) stored in ice for 20 days was evaluated. No differences in total volatile basic nitrogen (TVB-N), pH, carbohydrate or protein content of mucus were observed between the slaughter methods. Ice-slaughtered fish had lower bacteria counts at the beginning of storage, but higher counts than fish slaughtered by electricity at the end of storage (p < 0.05). However, no significant differences in the shelf life were observed between the slaughter methods evaluated (limit of acceptability – counts > 3 × 10⁶ CFU g⁻¹ – attained after 13–16 days). Results indicated that the chemical parameters evaluated have a limited applicability to assess the shelf life of grass carp stored in ice, since pH limit (6.8) was exceeded after 4 days, while TVB-N limit (30 mg%) was not attained after 20 days of storage.     

Development and validation of a methodology to qualitatively screening veterinary drugs in porcine muscle via an innovative extraction/clean-up procedure and LC-MS/MS analysis

A qualitative multiresidue method that facilitates rapid monitoring of veterinary drugs in porcine muscle is described. The method comprises the application of an innovative extraction/clean-up procedure, namely liquid-liquid extraction with partition at very low temperature (LLE-FPVLT), and analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Besides the high selectivity, sensitivity and specificity, this high-throughput method proved to be quite general as 34 veterinary drugs (from six distinct classes: tetracyclines, sulfonamides, penicillins, quinolones, macrolides and benzimidazoles) could be successfully detected. The whole screening procedure was validated according to the directives from European Commission Decision 2002/657/EC and guidelines for the validation of screening methods. Acceptable values for the evaluation parameters were achieved for all analytes (except for ampicillin, clindamycin and erythromycin). Finally, these very promising results have strengthened the possibility of inclusion of such a methodology as an integral part of the National Residue Control Plan scope of the Ministry of Agriculture, Livestock and Food Supply of Brazil.     

Discrimination between defective and non-defective Brazilian coffee beans by their volatile profile

The coffee roasted in Brazil is considered to be of low quality, due to the presence of defective coffee beans that depreciate the beverage quality. In view of the fact that coffee flavour is directly related to the volatile compounds produced during roasting, the objective of the present study was to perform a comparative evaluation of the volatile fraction of defective (black, immature, sour) and healthy coffee beans, in order to find possible chemical markers for detection of defective coffee beans in roasted coffee. Volatiles extraction and concentration was performed by solid phase micro-extraction (SPME) of the roasted coffee headspace, using a triple phase (divinylbenzene/carboxen/polydimethylsiloxane) fiber. Analysis of the volatile profiles was performed by GC–MS. The results obtained showed that the proposed methodology was adequate for extraction, concentration and analysis of the coffees volatile profile. Several substances were identified as possible markers for differentiating black, sour and immature beans from healthy coffee beans. Statistical analysis of the data by principal components (PCA) demonstrated that the volatile profile enables the differentiation of healthy and defective coffees. The data were separated into two major groups, one represented by immature and black beans and the other by healthy and sour coffee beans. Such results indicated that black and sour beans can be associated to fermentation of immature and of healthy beans, respectively.     

Quantitative chiral analysis of sugars by electrospray ionization tandem mass spectrometry using modified amino acids as chiral reference compounds

Rapid quantitative enantiomeric analysis of mannose, glucose, galactose, and ribose is achieved using electrospray ionization and cluster ion dissociation with data analysis by the kinetic method. Several modified amino acids (N-Ac-L-Phe, N-benzoyl-L-Phe, N-t-Boc-L-Phe, N-Ac-L-Pro, N-t-Boc-L-Pro, N-Fmoc-L-Pro, N-Ac-L-Tyr, O-Me-L-Tyr) and four transition divalent metal cations (Co2+, Cu2+, Ni2+, and Zn2+) were tested to select the best system for chiral recognition and quantitation of each sugar. Quantitative determinations of the enantiomeric compositions of sugar solutions were achieved using either multiple- or two-point calibration curves; differences between the actual and experimental values were <2% enantiomeric excess (ee).     

Advanced oxidation of caffeine in water: on-line and real-time monitoring by electrospray ionization mass spectrometry

High performance liquid chromatography (HPLC), ultraviolet spectroscopy (UV), and total organic carbon (TOC) analyses show that caffeine is quickly and completely degraded underthe oxidative conditions of the UV/H2O2,TiO2/ UV, and Fenton systems but that the organic carbon content of the solution decreases much more slowly. Continuous on-line and real-time monitoring by electrospray ionization mass (ESI-MS) and tandem mass spectrometric experiments (ESI-MS/MS) as well as high accuracy MS measurements and gas chromatography-mass spectrometry analysis show that caffeine is first oxidized to N-dimethylparabanic acid likely via initial OH insertion to the C4=C8 caffeine double bond. A second degradation intermediate, di(N-hidroxymethyl)parabanic acid, has been identified by ESI-MS and characterized by ESI-MS/MS and high accuracy mass measurements. This polar and likely relatively unstable compound, which is not detected by off-line GC-MS analysis, is likely formed via further oxidation of N-dimethylparabanic acid at both of its N-methyl groups and constitutes an unprecedented intermediate in the degradation of caffeine.     

Some considerations on the assessment of structural reliability

Some considerations on the assessment of structural reliability are presented. It is pointed out that the probabilities of failure of structures which can be calculated or estimated have no real quantitative significance: they are rather conventional, comparative values, but they can play a very important role in making possible rational comparisons between alternative designs.     

Seismic vulnerability of monumental buildings

Monumental buildings are by definition unique buildings that cannot be reduced to any standard structural scheme: this makes it difficult to evaluate their seismic reliability, because—in addition to the many uncertainties that are common to all existing (and in particular “old”) buildings—no statistics on the behaviour of similar buildings can be available. To overcome this problem, the macroelement approach has been proposed a few years ago and since then repeatedly used to analyse and compare the seismic response of monumental buildings: the structural organism is considered as the assemblage of few components (e.g. the whole façade of a church) whose behaviour is typical of the behaviour of analogous macroelements in other buildings, and whose possible collapse mechanisms can be identified. In these studies, quasi-static loads have been used, as indeed common in many analyses of the seismic behaviour of masonry structures. This paper accepts these simplifying assumptions, and shows how—assuming appropriate probabilistic properties of the relevant quantities and a “logical diagram” describing the relation between collapse of macroelements and whole building—the probability of collapse and damage of each macroelement and of the whole building under given horizontal loads can be assessed. The procedure is formulated in detail with special reference to churches, and illustrated on two example cases. The same procedure can be used as the basis of a statistical extrapolation aimed at evaluating the probability distributions of collapse and damage among monumental buildings that are similar with regard to both the macroelement typologies and the logical diagram.     

Simulation of wind loading and response of geometrically non-linear structures with particular reference to large antennas

The study of the response of wind-loaded flexible structures generates several problems, related to the collection of significant experimental data and the modelling of the random wind velocity field, fluid-structure interaction and actual structural behaviour. This paper presents some results of recent research on these problems.

The first part of the paper tackles the modelling and simulation of wind velocity and presents the treatment of some direct measurements on the site of an important broadcasting antenna located on Monte Nerone (Appennine Mountains) on the Italia watershed, 1500 m above sea level.

The second part deals with the problem of determining structural response under wind loading. Because of the impracticability of operating in the frequency domain in the presence of non-linearities, simulation and direct step-by-step integration in the time domain have been chosen. Two specific examples are presented, both pertaining to guyed antennas, for which non-linearities have been shown to be significant. The effects of ice formations on the mast and / orthe stays have also been investigated.