Effect of Post-harvest UV-B Irradiation on Polyphenol Profile and Antioxidant Activity in Flesh and Peel of Tomato Fruits

In the present study, the possibility of enhancing phenolic and flavonoid concentration in tomato (Solanum lycopersicum L.) fruits by post-harvest irradiation with UV-B light was assessed. Fruits of the commercial cv Money Maker (MM) and the mutant genotype high pigment-1 (hp-1), constitutively rich in these compounds, were harvested at mature green and turning stages and left to ripen within climatic chambers where they were daily treated with UV-B radiation (1 h, 6.08 kJ/m² day). In control chambers, UV-B radiation was screened by benzophenone-treated polyethylene film. The treatment was generally effective in increasing phenolic, flavonoid and flavonol concentration in both peel and flesh of MM and hp-1 fruits, although in this latter the positive response to UV-B treatment was mainly evident in fruits harvested at mature green stage. Following UV-B treatment, antioxidant activity increased in the peel of both genotypes independently from the harvesting stage and in the flesh of hp-1 fruits harvested at mature green stage. Hydroxycinnamic acids of both genotypes reacted to UV-B treatment differently depending on harvesting stage and tissue localisation, generally showing an increase in the peel of fruits harvested at mature green stage. With few exceptions, UV-B irradiation also induced a higher accumulation of individual flavonoids both in the peel and in the flesh of MM and hp-1 fruits independently from harvesting stage. Based on these results, UV-B irradiation can be considered a promising technique to increase the nutraceutical potential of tomato fruits by non-molecular tools.     

Evaluation of the Reveal and SafePath rapid Escherichia coli O157 detection tests for use on bovine feces and carcasses

The Reveal (Neogen Corp., Lansing, Mich.) and SafePath (SafePath Laboratories LLC, St. Paul, Minn.) tests were evaluated for their performance as beef fecal and beef carcass Escherichia coli O157:H7 monitoring tests. Agreement between these tests and a reference test system was determined using naturally contaminated bovine feces and beef carcasses. The reference system utilized immunomagnetic separation with plating onto cefixime, tellurite, sorbitol MacConkey agar, followed by colony testing using a serum agglutination test for the O157 antigen. Relative to this reference method, the Reveal test showed a sensitivity of 46% and a specificity of 82% on bovine feces and a specificity of 99% on carcass samples. The SafePath test, demonstrated a significantly higher sensitivity at 79% and a similar specificity of 79%. On carcass samples the SafePath test performed similarly to the Reveal test, demonstrating a specificity of 100% relative to the reference system. There was an insufficient number of E. coli O157-positive carcass samples to estimate precisely the sensitivity of these two methods. Both methods show promise as rapid carcass monitoring tests, but further field testing to estimate sensitivity is needed to complete their evaluation. The proportion of positive fecal samples for E. coli O157:H7 by the reference method ranged from 10.2% to 36% in 10 lots of cattle with an overall mean of 17.3% (39/225). Quarter carcass sponging of 125 carcasses revealed 1.6% positive for the pathogen (2/125).     

QoS guarantee in telecommunication networks: technologies and solutions

The aim of this paper is to show the effect of the presence of specific management functions within a network that offers quality of service (QoS). The objective is not privileging a particular technology but to highlight the importance to know which control functions a solution may use, which performance limits the functions have and what can be a realistic user expectation. The paper focuses on the meaning of QoS and on the applications requiring quality, then describes QoS solutions including transport technologies, QoS‐oriented technologies, parameters and management functions. In more detail, the effect on QoS provision of the following issues is investigated and discussed concerning the possibility (or not) to aggregate and differentiate traffic, the implementation of call admission control and of traffic filtering to limit flows to their committed rates. Again, the conclusions should not be considered a merit mark about technology, but only an investigation about: what users and customers should expect by the technologies using specific control functions evidencing that the real limitations are not imposed by a specific technology, whose features may be changed and extended, but by the application of control functions that can guarantee requirements' matching. Copyright © 2004 John Wiley & Sons, Ltd.     

Maximum Residue Levels of Veterinary Medicines in Relation to Food Safety: European Community Legislation and Ethical Aspects

Residues of veterinary medicinal products, as defined by the European Union, are “pharmacologically active substances (whether active principles, excipients or degradation products) and their metabolites which remain in foodstuffs obtained from animals to which the veterinary medicinal product in question has been administered”. The policy for Maximum Residue Limit (MRL) setting is focused on a high protection level for the consumer. MRL can be set when risk assessment shows no risk for the consumer. An MRL is the maximum concentration of residue following administration of a veterinary medicine which is legally permitted or acceptable in food under the laws of the EU. The responsibility for keeping residues under the MRL lies with veterinarians and farmers, using licensed animal medicines. Violative residues of veterinary medicines can occur as a result of improper use of a licensed product or through the illegal use of an unlicensed substance. Consequently, it became clear that prudent use of not only antimicrobials used for treatment and prevention of disease but also those used for growth promotion (e.g. β-agonists or steroid hormones) in farm animals is an integral part of good veterinary practice. In the following an overview of the European Community legislation on the studies required for residues is given. Ethical aspects are also considered. Received: March 6, 2008; accepted: March 17, 2008     

Degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) using zerovalent iron nanoparticles

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a common contaminant of soil and water at military facilities. The present study describes degradation of RDX with zerovalent iron nanoparticles (ZVINs) in water in the presence or absence of a stabilizer additive such as carboxymethyl cellulose (CMC) or poly(acrylic acid) (PAA). The rates of RDX degradation in solution followed this order CMC-ZVINs > PAA-ZVINs > ZVINs with k1 values of 0.816 +/- 0.067, 0.082 +/- 0.002, and 0.019 +/- 0.002 min(-1), respectively. The disappearance of RDX was accompanied by the formation of formaldehyde, nitrogen, nitrite, ammonium, nitrous oxide, and hydrazine by the intermediary formation of methylenedinitramine (MEDINA), MNX (hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine), DNX (hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine), TNX (hexahydro-1,3,5-trinitroso-1,3,5-triazine). When either of the reduced RDX products (MNX or TNX) was treated with ZVINs we observed nitrite (from MNX only), NO (from TNX only), N2O, NH4+, NH2NH2 and HCHO. In the case of TNX we observed a new key product that we tentatively identified as 1,3-dinitroso-5-hydro-1,3,5-triazacyclo-hexane. However, we were unable to detect the equivalent denitrohydrogenated product of RDX and MNX degradation. Finally, during MNX degradation we detected a new intermediate identified as N-nitroso-methylenenitramine (ONNHCH2NHNO2), the equivalentof methylenedinitramine formed upon denitration of RDX. Experimental evidence gathered thus far suggested that ZVINs degraded RDX and MNX via initial denitration and sequential reduction to the corresponding nitroso derivatives prior to completed decomposition but degraded TNX exclusively via initial cleavage of the N-NO bond(s).     

Diversity of stress tolerance in Lactobacillus plantarum, Lactobacillus pentosus and Lactobacillus paraplantarum: A multivariate screening study

Sixty-three strains of the taxonomically related species Lactobacillus plantarum subsp. plantarum, L. plantarum subsp. argentoratensis, L. paraplantarum and L. pentosus isolated from sourdoughs and other food and non-food sources and 14 strains of other members of the genus Lactobacillus were screened for their tolerance of acid, alkaline, heat, oxidative, osmotic, detergent and starvation stresses in order to evaluate the diversity of stress response. Most strains of the L. plantarum group were highly tolerant of acid, alkaline and osmotic stress and highly sensitive to detergent stress, while a larger diversity was found for other stress. Multivariate analysis allowed grouping the strains in clusters with similar response patterns. Stress response patterns in the L. plantarum group were similar to those of species of the L. casei/L. paracasei group but clearly different from those of other mesophilic Lactobacillus. No relationship was found between grouping obtained on the basis of stress response patterns and by genotypic fingerprinting (rep-PCR), nor with the taxonomic position or isolation source of the strains. Further experiments with selected strains showed that exponential phase cells were generally but not always more sensitive than stationary phase cells. The ability to grow under stressful conditions showed a slightly better correlation with the ecological conditions prevailing in the isolation niches of the strains.This study will be the basis for further investigations to identify and exploit the basis of diversity in the stress response of lactic acid bacteria.     

Influence of Ion Induced Local Coulomb Field and Polarity on Charge Generation and Efficiency in Poly(3‐Hexylthiophene)‐Based Solid‐State Dye‐Sensitized Solar Cells

Dye‐sensitized solar cells (DSSC) are a realistic option for converting light to electrical energy. Hybrid architectures offer a vast materials library for device optimization, including a variety of metal oxides, organic and inorganic sensitizers, molecular, polymeric and electrolytic hole‐transporter materials. In order to further improve the efficiency of solid‐state dye‐sensitized solar cells, recent attention has focused on using light absorbing polymers such as poly(3‐hexylthiophene) (P3HT), to replace the more commonly used “transparent” 2,2′,7,7′‐tetrakis‐(N,N‐di‐p‐methoxyphenyl‐amine)9,9′spiro‐bifluorene (spiro‐OMeTAD), in order to enhance the light absorption within thin films. As is the case with spiro‐OMeTAD based solid‐state DSSC, the P3HT‐based devices improve significantly with the addition of lithium bis(trifluoromethylsulfonyl)imide salts (Li‐TFSI), although the precise role of these additives has not yet been clarified in solid‐state DSCs. Here, we present a thorough study on the effect of Li‐TFSI in P3HT based solid‐state DSSC incorporating an indolene‐based organic sensitizer termed D102. Employing ultrafast transient absorption and cw‐emission spectroscopy together with electronic measurements, we demonstrate a fine tuning of the energetic landscape of the active cell components by the local Coulomb field induced by the ions. This increases the charge transfer nature of the excited state on the dye, significantly accelerating electron injection into the TiO₂. We demonstrate that this ionic influence on the excited state energy is the primary reason for enhanced charge generation with the addition of ionic additives. The deepening of the relative position of the TiO₂ conduction band, which has previously been thought to be the cause for enhanced charge generation in dye sensitized solar cells with the addition of lithium salts, appears to be of minor importance in this system.     

The influence of muscular lengthening on cramps

The risks of acquisition of hepatitis C infection, the histological spectrum of liver disease, and the presence of viraemia were investigated in anti-hepatitis C virus (HCV) antibody positive blood donors. All 357 (0.64%) blood donors to the South Australian Red Cross Transfusion Service found to have anti-HCV antibody during the first seven months of testing in 1990 were assessed, and 70 (19.6%) were found to have elevated alanine transaminase levels. These subjects were referred for participation in the study; 31 presented for enrollment. Sixteen (52%) of the 31 patients had previously used intravenous drugs, four (13%) had been transfused, two (6%) had a history of occupational exposure to blood, and three (10%) had tattoos and ear-piercing as possible risk factors for acquisition of hepatitis C. There was no history of parenteral exposure in six (16%). None of these donors had clinical evidence of liver disease, but in all 24 of the 31 who had a liver biopsy there was histological evidence of significant liver damage. Twelve had evidence of chronic active hepatitis. All 24 subjects biopsied were viraemic as judged by the presence of HCV RNA in serum.     

Evolution of enterohemorrhagic Escherichia coli hemolysin plasmids and the locus for enterocyte effacement in shiga toxin-producing E. coli

This study assessed the diversity of the enterohemorrhagic Escherichia coli (EHEC) hemolysin gene (ehxA) in a variety of Shiga toxin-producing E. coli (STEC) serotypes and the relationship between ehxA types and virulence markers on the locus for enterocyte effacement (LEE). Restriction fragment length polymorphism of the ehxA gene and flanking sequences and of the E. coli attaching and effacing (eae) gene was determined for 79 EHEC hemolysin-positive STEC isolates of 37 serotypes. Two main groups of EHEC hemolysin sequences and associated plasmids, which corresponded to the eae-positive and the eae-negative isolates, were delineated. Comparisons of the ehxA gene sequences of representative isolates of each group showed that this gene and the rest of the EHEC hemolysin operon are highly conserved. Digestion of an ehxA PCR product with the restriction endonuclease TaqI showed a unique restriction pattern for eae-negative isolates and another one for isolates of serotypes O157:H7 and O157:NM. A conserved fragment of 5.6 kb with four potential open reading frames was identified on the EHEC hemolysin plasmid of eae-positive STEC. Phylogenetic analysis of a subset of 27 STEC isolates, one enteropathogenic E. coli isolate, and a K-12 reference isolate showed that eae-positive STEC isolates all belong to a single evolutionary lineage and that the EHEC hemolysin plasmid and the ehxA gene evolved within this lineage without recent horizontal transfer. However, the eae gene and the LEE appear to have been transferred horizontally within this STEC lineage on several occasions. The reasons for the lack of transfer or maintenance of the LEE in other STEC lineages are not clear and require further study.     

Influence of Boundary Conditions in a Finite-Element Analysis of River Levees

The effects of boundary conditions on the stability of a river levee built on a low-permeability soil layer overlying a coarse-grained deposit were studied by using the finite-element method (FEM). The FEM analyses could predict stable or unstable levee conditions depending on the assumed distance between the levee and the external boundary of the mesh where the water table was assumed undisturbed. Possible causes of this notable drawback are discussed. The calibration of the numerical seepage model, through a back analysis of piezometer measurements, that could limit the observed boundary effects is suggested.