Determination of the fracture toughness by applying a structural integrity approach to pre-cracked Small Punch Test specimens

The Failure Assessment Diagram (FAD) is a procedure for evaluating the structural integrity of cracked components. The component’s failure conditions (load and crack size) are based on the material fracture properties (K_mat) considering its plastic behavior. In this paper, a new methodology that combines the FAD approach and the load–displacement curve obtained from pre-cracked Small Punch Test (SPT) specimens is presented, in order to estimate the fracture toughness of 15.5PH stainless steel. This research is based on Finite Element Modeling (FEM) of the pre-cracked specimen to determine both the plastic collapse load and the stress intensity factors during the loading process. A set of interrupted tests on pre-cracked SPT specimens are also conducted in order to identify the initiation point of the crack propagation. This set of numerical and experimental values allows the toughness ratio (K_r) and load ratio (L_r), at the instant the cracked specimen fails, to be determined. The only unknown variable in this process is the value of the material toughness, K_mat. The parameters in question are then combined with the FAD of the material generated from the different options available on the ASME-API 579 procedure, thus yielding an estimate for the value K_mat. Finally, to evaluate the accuracy of this methodology, predicted toughness values are compared to those from normalized tests of the material being analyzed.     

Factors affecting growth of foodborne pathogens on minimally processed apples

Escherichia coli O157:H7, Salmonella and Listeria innocua increased by more than 2 log₁₀ units over a 24 h period on fresh-cut ‘Golden Delicious’ apple plugs stored at 25 and 20 °C. L. innocua reached the same final population level at 10 °C meanwhile E. coli and Salmonella only increased 1.3 log₁₀ units after 6 days. Only L. innocua was able to grow at 5 °C. No significant differences were observed between the growth of foodborne pathogens on fresh-cut ‘Golden Delicious’, ‘Granny Smith’ and ‘Shampion’ apples stored at 25 and 5 °C. The treatment of ‘Golden Delicious’ and ‘Granny Smith’ apple plugs with the antioxidants, ascorbic acid (2%) and NatureSeal^® (6%), did not affect pathogen growth. The effect of passive modified atmosphere packaging (MAP) on the growth of E. coli, Salmonella and L. innocua on ‘Golden Delicious’ apple slices was also tested. There were no significant differences in growth of pathogens in MAP conditions compared with air packaging of ‘Golden Delicious’ apple plugs, but the growth of mesophilic and psychrotrophic microorganisms was inhibited. These results highlight the importance of avoiding contamination of fresh-cut fruit with foodborne pathogens and the maintenance of the cold chain during storage until consumption.     

Fate of Escherichia coli O157:H7, Salmonella and Listeria innocua on minimally-processed peaches under different storage conditions

Consumption of fresh-cut produce has sharply increased recently causing an increase of foodborne illnesses associated with these products. As generally, acidic fruits are considered ‘safe’ from a microbiological point of view, the aim of this work was to study the growth and survival of Escherichia coli O157:H7, Salmonella and Listeria innocua on minimally-processed peaches. The three foodborne pathogens population increased more than 2 log₁₀ units on fresh-cut peach when stored at 20 and 25 °C after 48 h. At 10 °C only L. innocua grew more than 1 log₁₀ unit and it was the only pathogen able to grow at 5 °C. Differences in growth occurred between different peach varieties tested, with higher population increases in those varieties with higher pH (‘Royal Glory’ 4.73 ± 0.25 and ‘Diana’ 4.12 ± 0.18). The use of common strategies on extending shelf life of fresh-cut produce, as modified atmosphere packaging and the use of the antioxidant substance, ascorbic acid (2% w/v), did not affect pathogens’ growth at any of the temperatures tested (5 and 25 °C). Minimally-processed peaches have shown to be a good substrate for foodborne pathogens’ growth regardless use of modified atmosphere and ascorbic acid. Therefore, maintaining cold chain and avoiding contamination is highly necessary.     

Local boron doping quantification in homoepitaxial diamond structures

The capability of transmission electron microscopy (TEM) using the high angle annular dark field mode (HAADF, also labelled Z-contrast) to quantify boron concentration, in the high doping range between 10¹⁹ cm^? 3 and 10²¹ cm^? 3, is demonstrated. Thanks to the large relative variation of atomic number Z between carbon and boron, doping concentration maps and profiles are obtained with a nanometer-scale resolution. A novel numerical simulation procedure allows the boron concentration quantification and demonstrates the high sensitivity and spatial resolution of the technique.     

Smart oil recovery

Fuzzy-logic-based expert systems assist Brazilian engineers with the drilling, pumping, and processing of offshore oil, cutting costs without compromising safety. The authors discuss these applications of fuzzy logic control     

Das Gesetz der Volumenkonstanz als alleinige Voraussetzung bei der Ermittlung von Streck- und Tiefziehfähigkeit aus Ergebnissen des Zugversuchs

Bedeutung der Verfestigungs- und Anisotropiekoeffizienten für die Streck- und Tiefziehfähigkeit von Blech. Kennzeichnung der Umformbarkeit unter der Voraussetzung der Volumenkonstanz beim Umformen. Ermittlung von Kennwerten für die Streck- und Tiefziehfähigkeit aus dem Zusammenhang zwischen Höchstkraft und zugeordneter Dehnung im Zugversuch.     

The formation of phenolic diterpenes in Rosmarinus officinalis L. under Mediterranean climate

 The formation of phenolic diterpenes in the leaves of rosemary plants grown under Mediterranean climate was investigated. Low precipitation coincided with high solar radiation during the summer, resulting in water and light stress of the plants. The highest concentrations of the major diterpenes carnosic acid and carnosol were found during the winter and the lowest concentrations during the summer, which is likely to be the result of their enzymatic conversion in the presence of singlet oxygen. All other diterpenes followed different trends during the season. The concentration of carnosic acid increased with the relative water content of the leaf but decreased with increasing solar radiation and temperature. 11,12-di-O-Methylisorosmanol was found for the first time in rosemary leaves. Received: 22 March 1999     

Does fiscal decentralization affect the effectiveness of intergovernmental grants? European regional policy and Spanish autonomous regions

We suspect that the efficiency of intergovernmental grants is related to the level of fiscal autonomy of the subsidized government. In this paper we construct and estimate a panel data model capturing the role of fiscal federalism on the effectiveness of EU structural actions in enhancing public investment. We use data from the 17 Spanish regions for the period 1993–2007. Results unambiguously support the hypothesis that the effectiveness of the structural funds decreases with larger fiscal autonomy, which could reflect the fact that fiscal decentralization in Spain has been focused to larger taxation autonomy without affecting regional income redistribution.     

Microbiological and physicochemical quality of fresh-cut apple enriched with the probiotic strain Lactobacillus rhamnosus GG

The effectiveness as protective culture of the probiotic Lactobacillus rhamonosus GG (L. rham. GG) against Salmonella and Listeria monocytogenes on minimally-processed apples throughout storage as well as its effect on apple quality and natural microflora was evaluated. Survival to subsequent exposure to gastric stress was also reported. Apples were cut into wedges and dipped in a solution containing Salmonella and L. monocytogenes (10⁵ cfu mL⁻¹) and/or L. rham. GG (10⁸ cfu mL⁻¹). Apple wedges were packed and stored at 5 and 10 °C. Periodically, microbial population, bacterial survival to gastric stress and quality of apple wedges were evaluated. Although Salmonella was not affected by co-inoculation with L. rham. GG, L. monocytogenes population was 1-log units lower in the presence of L. rham. GG. L. rham. GG population maintained over recommended levels for probiotic action (10⁶ cfu g⁻¹) along storage, however, viable cells after gastric stress were only above this level during the first 14 days. Pathogen survival after gastric stress was <1% after 7 days at 5 °C. Moreover, apple wedges quality was not affected by L. rham. GG addition. Thus, L. rham. GG could be a suitable probiotic for minimally-processed apples capable to reduce L. monocytogenes growth; nevertheless shelf life should not be higher to 14 days to guarantee the probiotic effect.