Excimer Laser Processing of Nodular Iron

Excimer laser processing is expected to improve the wear properties and the oxidation resistance of cast iron surfaces. In the present study, an XeCl laser prototype was used to change the surface morphology of nodular iron samples under high energy ultraviolet exposure. Roughness evolution results from ablation and, above all, from moving of the molten superficial layer, due to both high temperature and pressure involved during the laser shot. Conventional metallography was carried out to determine the mechanisms governing the modification of surface profiles. These were shown to be both a wide and a local phenomena, i.e. involved at two different scales: that of the laser spot and that of the nodule. The plasma high pressure applied to the surface moves the molten material towards the periphery of the spot, where it freezes by self quenching with a high cooling rate. The surface profile is also modified by the formation of a rim surrounding each solid heterogeneity such as graphite spheroids. The width of the rims did not depend on the sizes of nodules or inclusions. The study suggests a wave emission mechanism to interpret formation of the rims.     

Preparation and properties of polypyrrole/bentonite/vanadium (V) oxide ternary composites

The preparation and characterization of new ternary composites formed by the redox/intercalative reaction of pyrrole with the lamellar bentonite/V₂O₅ composite are reported. The generation of a conducting polymer combined with a mixed semiconductor oxide-clay material provided an interesting material where the conductivity depends upon the polypyrrole content, and on the particular way it influences the Li⁺ ions migration in the films.     

CO2 addition on the non-oxidative dehydro-aromatization of methane over MoMCM-22

This work aims at studying the effect of CO₂ addition in the non-oxidative conversion of methane over a Mo-containing MCM-22 zeolite. Catalyst characterization made use of X-ray fluorescence, textural analysis, X-ray diffraction and diffuse reflectance spectroscopy. Molybdenum was present as highly condensed species with octahedral coordination, such as (Mo₇O₂₄)₆ and MoO₃ species. Catalytic tests were carried out at atmospheric pressure and 700 °C, with WHSV of 90g_CH4 · g _Mo ^?1  h^?1. Coke species were studied by thermogravimetric analysis and thermoprogrammed oxidation. Besides the carbidic carbon, two other types of coke were observed: one associated to molybdenum and the other associated to Brönsted acid sites located both on the catalyst surface and inside zeolite pores. The species associated to acid sites, known to be responsible for polyaromatics formation and catalyst deactivation, were reduced in a more significant way by the use of CO₂, increasing the catalyst stability.     

Influence of slaughter season and muscle type on fatty acid composition, conjugated linoleic acid isomeric distribution and nutritional quality of intramuscular fat in Arouquesa-PDO veal

The effects of the slaughter season and muscle type on lipid and conjugated linoleic acid (CLA) contents, fatty acid composition and isomeric profile of CLA in Arouquesa veal, from calves reared according to the specifications of the protected designation of origin (PDO), were assessed. Arouquesa purebred calves (n = 31) were raised in a traditional production system, slaughtered in early autumn (October) or late spring (June), and the longissimus dorsi and semitendinosus muscles were sampled for analysis. Arouquesa-PDO veal only showed seasonal differences in the levels of some minor fatty acids (16:1c9, 17:1c9, 18:1t, 18:3n − 3, 20:0 and 22:4n − 6) and CLA isomers (t12,t14, t9,t11 and c11,t13). Furthermore, significant interactions between the slaughter season and muscle type were obtained for several fatty acids and CLA isomers, total lipids and CLA, and the PUFA/SFA ratio. In both seasons, veal-PDO depicts values of pasture-fed cattle. From a human nutritional perspective, veal-PDO in both slaughter seasons has relatively high CLA contents and percentages of the c9,t11 CLA isomer, which is favourable, while the n − 6/n − 3 ratios are within the recommended values for the human diet. In conclusion, the results suggest that intramuscular fat in Arouquesa-PDO veal has high nutritional value throughout the year.     

Sampling of bread for added sodium as determined by flame photometry

Sodium content in bread is a growing interest in public health. This study was undertaken to evaluate the role of sampling in the dispersion of salt content in bread. Ten brands of bread representing the consumed types were collected from the largest retail places in Portugal. Their sodium and potassium contents were determined using flame photometry. The ratio sodium/potassium was used as an indicator of salinity. Sodium content varied from 490 ± 21 to 724 ± 9/100 g of white bread. Data from uncertainty budgets demonstrated that sampling is the dominant contributor (>55%). According to our results for sodium in bread, to pool samples from different sampling points can disguise the heterogeneity of the results. Therefore, the importance of the number of primary sample units and of the identification of sampling points is highlighted. This provides the necessary information to the users of Food Composition Databanks who wish to have an overview of the parameters, which influence the estimation of sodium intake values, which may affect the diet-disease relationship.     

Effect of the feeding system on intramuscular fatty acids and conjugated linoleic acid isomers of beef cattle,with emphasis on their nutritional value and discriminatory ability

Thirty two Alentejano purebred bulls were used to investigate the effect of four feeding systems (pasture only, pasture feeding followed by 2 or 4 months of finishing on concentrate, and concentrate only) on meat fatty acid composition (GC-FID), including conjugated linoleic acid (CLA) isomeric distribution (Ag[+]–HPLC–DAD). In addition, meat fatty acids and CLA isomers were used to elucidate the impact of the different feeding regimens on the nutritional value of intramuscular fat and their usefulness as chemical discriminators of meat origin. The diet had a major impact on the fatty acid composition of beef (affected 27 of 36 fatty acids and 10 of 14 CLA isomers), which was independent of the fatty acid concentration. Beef fat from pasture-fed animals had a higher nutritional quality relative to that from concentrate-fed bulls. Finally, meat fatty acid composition was an effective parameter to discriminate between ruminant feeding systems, including different finishing periods on concentrate.     

Antimicrobial‐Resistance Genetic Markers in Potentially Pathogenic Gram Positive Cocci Isolated from Brazilian Soft Cheese

Although most Brazilian dairy products meet high technological standards, there are quality issues regarding milk production, which may reduce the final product quality. Several microbial species may contaminate milk during manufacture and handling. If antimicrobial usage remains uncontrolled in dairy cattle, the horizontal transfer of antimicrobial resistance genes in foodstuffs may be of particular concern for both food producers and dairy industry. This study focused on the evaluation of putative Gram positive cocci in Minas cheese and of antimicrobial and biocide resistance genes among the isolated bacteria. Representative samples of 7 different industrially trademarked Minas cheeses (n = 35) were processed for selective culture and isolation of Gram positive cocci. All isolated bacteria were identified by DNA sequencing of the 16S rRNA gene. Antimicrobial resistance genes were screened by PCR. Overall, 208 strains were isolated and identified as follows: Enterococcus faecalis (47.6%), Macrococcus caseolyticus (18.3%), Enterococcus faecium (11.5%), Enterococcus caseliflavus (7.7%), Staphylococcus haemolyticus (7.2%), Staphylococcus aureus (4.3%), Staphylococcus epidermidis (2.9%), and Enterococcus hirae (0.5%). The genetic markers mecA (78.0%) and smr (71.4%) were the most prevalent, but others were also detected, such as blaZ (65.2%), msrA (60.9%), msrB (46.6%), linA (54.7%), and aacA‐aphD (47.6%). The occurrence of opportunist pathogenic bacteria harboring antimicrobial resistance markers in the cheese samples are of special concern, since these bacteria are not considered harmful contaminating agents according to the Brazilian sanitary regulations. However, they are potentially pathogenic bacteria and the cheese may be considered a reservoir for antimicrobial resistance genes available for horizontal transfer through the food chain, manufacturing personnel and consumers.     

Development of active plastic crate and evaluation of phytopathogenic and pathogenic food spoilage micro‐organism inhibition

BACKGROUND: The plastic crates used in fruit and vegetable shipping can be vehicles of disease dissemination among production fields, since there is a chance of phytopathogenic micro‐organism adhesion on the crate surfaces when in contact with soil, contaminated produce or handling. The aim of this study was to develop an active plastic crate incorporated with a triclosan‐based antimicrobial agent and to evaluate its efficiency of micro‐organism inhibition. RESULTS: Staphylococcus aureus (a human pathogen), Clavibacter michiganensis ssp. michiganensis and Erwinia carotovora ssp. carotovora (phytopathogens) were the most sensitive micro‐organisms when in contact with samples of plastic crate incorporated with 30 g kg^?1 of antimicrobial agent. They presented diameters of approximately 5.0, 3.5 and 3.5 cm respectively in the halo test. Mean specific growth rates decreased in samples with 30 g kg^?1 of antimicrobial agent, compared with control samples, from 1.13 to 0 h^?1 for S. aureus, from 1.26 to 0.47 h^?1 for Escherichia coli and from 1.75 to 0.18 h^?1 for Listeria monocytogenes. The antimicrobial agent did not influence the mechanical properties of the crates. CONCLUSION: The active plastic crate has great potential to contribute to the safety of horticultural produce by restraining the proliferation of micro‐organisms among production fields. Copyright © 2008 Society of Chemical Industry